Journal articles on the topic 'Malaria – Gene therapy'
To see the other types of publications on this topic, follow the link: Malaria – Gene therapy.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Malaria – Gene therapy.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Rodrigues, Mauricio M., and Irene S. Soares. "Gene-therapy for malaria prevention." Trends in Parasitology 30, no. 11 (November 2014): 511–13. http://dx.doi.org/10.1016/j.pt.2014.09.005.
Full text
2
Shehzad, Raafay. "Gene Therapy: A Promising Therapeutic Strategy for Malaria." University of Ottawa Journal of Medicine 8, no. 2 (November 15, 2018): 40–44. http://dx.doi.org/10.18192/uojm.v8i2.3651.
Full textAbstract:
Malaria is a serious illness caused by the Plasmodium parasite, which places approximately 3.5 billion people at risk. Currently, preventative measures are key in combatting this disease. However, gene therapy is an emerging field that shows promising results for the treatment of malaria, by modifying cells through the delivery of genetic material. Most notable was the discovery of CRISPR-Cas9, which not only allows deleterious mutations to be repaired, but does so with specificity, speed, and simplicity. There are numerous ongoing trials focusing on gene therapy in malaria treatment and prevention. They involve different approaches such as the genetic modification of vector mosquitoes to interfere with malaria transmission, use of CRISPR-Cas9, maternal-effect dominant embryonic arrest, homing endonuclease gene drive systems, and the design of specific Morpholino oligomers to interfere with the expression of parasitic characteristics. Overall, this emerging field shows promising results to treat and prevent not just malaria, but other diseases such as cancer, diabetes, and obesity.
3
Zhang, De-Liang, Jian Wu, Binal N. Shah, Katja C. Greutélaers, Manik C. Ghosh, Hayden Ollivierre, Xin-zhuan Su, et al. "Erythrocytic ferroportin reduces intracellular iron accumulation, hemolysis, and malaria risk." Science 359, no. 6383 (March 29, 2018): 1520–23. http://dx.doi.org/10.1126/science.aal2022.
Full textAbstract:
Malaria parasites invade red blood cells (RBCs), consume copious amounts of hemoglobin, and severely disrupt iron regulation in humans. Anemia often accompanies malaria disease; however, iron supplementation therapy inexplicably exacerbates malarial infections. Here we found that the iron exporter ferroportin (FPN) was highly abundant in RBCs, and iron supplementation suppressed its activity. Conditional deletion of the Fpn gene in erythroid cells resulted in accumulation of excess intracellular iron, cellular damage, hemolysis, and increased fatality in malaria-infected mice. In humans, a prevalent FPN mutation, Q248H (glutamine to histidine at position 248), prevented hepcidin-induced degradation of FPN and protected against severe malaria disease. FPN Q248H appears to have been positively selected in African populations in response to the impact of malaria disease. Thus, FPN protects RBCs against oxidative stress and malaria infection.
4
Oboh, Mary Aigbiremo, Daouda Ndiaye, Hiasindh Ashmi Antony, Aida Sadikh Badiane, Upasana Shyamsunder Singh, Nazia Anwar Ali, Praveen Kumar Bharti, and Aparup Das. "Status of Artemisinin Resistance in Malaria Parasite Plasmodium falciparum from Molecular Analyses of the Kelch13 Gene in Southwestern Nigeria." BioMed Research International 2018 (October 3, 2018): 1–5. http://dx.doi.org/10.1155/2018/2305062.
Full textAbstract:
Evolution and spread of malaria parasite Plasmodium falciparum capable of evading antimalarials are the prime concern to malaria control. The currently effective drug, artemisinin (ART), is under threat due to detection of ART-resistant P. falciparum parasites in the Southeast Asian countries. It has been shown that amino acid (AA) mutations at the P. falciparum Kelch13 (Pfk13) gene provide resistance to ART. Nigeria, a part of the Sub-Saharan Africa, is highly endemic to malaria, contributing quite significantly to malaria, and resistance to chloroquine (CQ) and sulfadoxine-pyrimethamine (SP) combination drugs has already been reported. Since artemisinin combined therapy (ACT) is the first-line drug for treatment of uncomplicated malaria in Nigeria and five amino acid mutations have been validated in the Pfk13 gene alongside with candidate mutations for ART resistance, we performed molecular surveillance for mutations (following PCR and DNA sequence analyses) in this gene from two southwestern states of Nigeria. Statistical analyses of DNA sequences were also performed following different evolutionary models. None of the different validated and candidate AA mutations of Pfk13 gene conferring resistance to ART could be detected in P. falciparum sampled in the two southwestern states of Nigeria. In addition, DNA sequencing and sequence analyses indicated neither evolutionary selection pressure on the Pfk13 gene nor association of mutations in Pfk13 gene with mutations of other three genes conferring resistance to CQ and SP. Therefore, based on the monomorphism at the Pfk13 gene and nonassociation of mutations of this gene with mutations in three other drug-resistant genes in malaria parasite P. falciparum, it can be proposed that malaria public health is not under immediate threat in southwestern Nigeria concerning ART resistance.
5
Suwandi, Jhons Fatriyadi, Betta Kurniawan, Hanna Mutiara, and Aila Karyus. "PfCRT GENE POLYMORPHISMS IN PLASMODIUM FALCIPARUM ISOLATES FROM MALARIA PATIENTS IN MALARIA ENDEMIC AREAS USING ACT AS STANDARD THERAPY." Majalah Kedokteran Sriwijaya 54, no. 1 (August 8, 2022): 15–21. http://dx.doi.org/10.32539/mks.v54i1.15137.
Full textAbstract:
The pfcrt gene is a biomarker to determine the resistance of Plasmodium falciparum to chloroquine and amodiaquine. When chloroquine was switched to ACT, it is very likely that there will be an increase in wild type strains (pfcrt K76) due to the absence of exposure to chloroquine. Currently chloroquine has not used for malaria treatment. The aims of this study were to identify polymorphisms in the pfcrt gene and phylogenetic analysis of Plasmodium falciparum isolates from malaria patients in Pesawaran Regency, Lampung Province. This research is a laboratory research by analyzing blood samples which are stored biological materials (BBT). DNA isolation was carried out using a DNA isolation kit QIAmp DNA Mini kit from Qiagen, followed by amplification using an appropriate primer. The amplification results were followed by sequencing and then analyzed using Mega 10. The results showed that all samples had mutations in codons 76 (K76T) and 72 (C72S) of the pfcrt gene. Pesawaran isolates were closely related to other isolates. The conclusion of this study is that polymorphisms were found in codons 72 and 76 of the PfCRT gene, although chloroquine has long been abandoned as an antimalarial. The sequenced pesawaran isolates were also related to other isolates.
6
Santos, Thalita Grazielly, Thatiane Danielly Santos, Nilton Nascimento dos Santos Junior, Mikael Santana dos Santos, Thatiany Santos Araújo, Jennifer Soares de Almeida, João Junior Scapin Telis, and Julia De Lima Santos. "Origem da Relação entre Malária e Anemia Falciforme / Origin of the Relationship Between Malaria and Sickle Cell Anemia." ID on line. Revista de psicologia 16, no. 61 (July 31, 2022): 128–40. http://dx.doi.org/10.14295/idonline.v16i61.3516.
Full textAbstract:
Resumo: A malária é uma doença tropical e parasitária que mais causa impasses sociais e econômicos em todo o mundo, sendo considerada um problema de saúde pública. É causada pelo protozoário do gênero Plasmodium, sendo três espécies os de maiores ocorrências e transmitida pelo mosquito Anopheles. A anemia falciforme é uma doença sanguínea causada por uma mutação de ponto que permite a formação de uma proteína truncada, a hemoglobina S. Os indivíduos afetados são homozigotos e como consequência fenotípica tem-se o aparecimento de hemácias no formato de foice. O objetivo da revisão narrativa é realizar uma pesquisa bibliográfica que demonstre a relação entre malária e anemia falciforme. Este foi realizado nas bases de dados Scientific Eletronic Library Online (Scielo) e PubMed, cujos descritores consistem em “anemia falciforme”, “relação”, “malária”, “efeito materno”, “hipótese de Haldane”, “sickle cell disease”. A relação entre anemia falciforme e malária é notada, predominantemente, em regiões endêmicas para malária, dado os estudos obtidos por Haldane e a hipótese do efeito materno. Portanto, conclui-se que pessoas portadoras do gene da anemia falciforme possuem relutância em contrair malária.Palavras-chave: anemia falciforme, relação, malária, efeito materno, hipótese de Haldane, sickle cell disease.Abstract: Malaria is a tropical and parasitic disease that causes most social and economic impasses around the world, being considered a public health problem. It is caused by the protozoan of the genus Plasmodium, with three species being the most frequent and transmitted by the Anopheles mosquito. Sickle cell anemia is a blood disease caused by a point mutation that allows the formation of a truncated protein, hemoglobin S. Affected individuals are homozygous and as a phenotypic consequence there is the appearance of sickle-shaped red blood cells. The objective of the narrative review is to carry out a bibliographic research that demonstrates the relationship between malaria and sickle cell anemia. This was carried out in the Scientific Electronic Library Online (Scielo) and PubMed databases, whose descriptors consist of “sickle cell anemia”, “relationship”, “malaria”, “maternal effect”, “Haldane hypothesis”, “sickle cell disease” . The relationship between sickle cell anemia and malaria is noted predominantly in malaria-endemic regions, given the studies obtained by Haldane and the hypothesis of maternal effect. Therefore, it is concluded that people carrying the sickle cell anemia gene are reluctant to contract malaria.Keywords: sickle cell anemia, relationship, malaria, maternal effect, Haldane hypothesis, sickle cell disease.
7
Das, Sabyasachi, Subhankar Manna, Bhaskar Saha, Amiya Kumar Hati, and Somenath Roy. "Novel pfkelch13 Gene Polymorphism Associates With Artemisinin Resistance in Eastern India." Clinical Infectious Diseases 69, no. 7 (December 9, 2018): 1144–52. http://dx.doi.org/10.1093/cid/ciy1038.
Full textAbstract:
Abstract Background Artesunate-sulfadoxine-pyrimethamine (ASSP) is the frontline artemisinin combination therapy (ACT) in India. Random, irrational, subtherapeutic artemisinin doses and self-medication with ACT along with predominance of sulfadoxine-pyrimethamine resistance parasite invoked a strong possibility of emerging artemisinin-resistant malaria parasites. Methods This study involved 226 patients with uncomplicated Plasmodium falciparum infection who had successfully completed the 42 days follow-up after ASSP combination therapy from April 2014 to January 2016. We assessed the ASSP treatment efficacy by evaluating parasite clearance half-life, pfkelch13, and other (pfdhfr, pfdhps, pfmdr1, pfcrt) gene mutations and survival of parasites as detected by an ex vivo ring-stage survival assay (RSA). Findings Slow-clearing infections with longer parasite clearance half-lives (>5 hours) were observed in 12% isolates. Cure rate after ASSP treatment was declining to about 84.1%. ASSP failure was recorded in 15.9% (early treatment failure, 7.9%; late treatment failure, 7.9%) of isolates. In sum, 24 patients (10.6%) had parasite clearance half-lives greater than 5 hours with pfkelch13 polymorphism after 441 codon; in 15 of those patients (6.6%), parasites had not cleared by 72 hours after initiation of therapy. Median ex vivo ring-stage survival rate of these isolates was very high (12.2%; 95% confidence interval [CI], 10.9–13.8) from that of cured patients (0.9%; 95% CI, 0.09–1.07). Of these 15 patients, 13 patients had pfkelch13 G625R polymorphism, whereas 2 patients contained R539T polymorphism. As per the World Health Organization guideline, these 15 isolates were true artemisinin-resistant isolates. Interpretation Identification of artemisinin-resistant isolates in India together with new mutations and increasing combination therapy failures blow alarms for urgent malaria control.
8
Magro, Paola, Ilaria Izzo, Barbara Saccani, Salvatore Casari, Silvio Caligaris, Lina Rachele Tomasoni, Alberto Matteelli, Annamaria Lombardi, Antonella Meini, and Francesco Castelli. "A strange case of Malaria in a Nigerian native boy." Mediterranean Journal of Hematology and Infectious Diseases 9, no. 1 (March 1, 2017): e2017023. http://dx.doi.org/10.4084/mjhid.2017.023.
Full textAbstract:
The protective role of SCT in malaria endemic areas has been proved and prevalence of HbS gene in malaria endemic areas is high. Splenic infarction is a well-known complication of SCT, rarely associated with malaria. A Nigerian boy was admitted to our ward after returning from his country of origin, for P. falciparum malaria. He underwent abdominal US for upper right abdominal pain, showing cholecystitis and multiple splenic abscesses. Empiric antibiotic therapy was undertaken. Bartonella, Echinococcus, Entamoeba serologies, blood cultures, Quantiferon test, coproparasitologic exam were negative; endocarditis was excluded. He underwent further blood exams and abdomen MRI, confirming the presence of signal alterations areas, with radiographic appearance of recent post-infarction outcomes. Hemoglobin electrophoresis showed a percentage of HbS of 40.6% and a diagnosis of SCT was made.Splenic infarction should be taken into account in patients with malaria and localized abdominal pain. Moreover, diagnosis of SCT should be considered.
9
Lefterova, Martina I., Indre Budvytiene, Johanna Sandlund, Anna Färnert, and Niaz Banaei. "Simple Real-Time PCR and Amplicon Sequencing Method for Identification of Plasmodium Species in Human Whole Blood." Journal of Clinical Microbiology 53, no. 7 (May 13, 2015): 2251–57. http://dx.doi.org/10.1128/jcm.00542-15.
Full textAbstract:
Malaria is the leading identifiable cause of fever in returning travelers. AccuratePlasmodiumspecies identification has therapy implications forP. vivaxandP. ovale, which have dormant liver stages requiring primaquine. Compared to microscopy, nucleic acid tests have improved specificity for species identification and higher sensitivity for mixed infections. Here, we describe a SYBR green-based real-time PCR assay forPlasmodiumspecies identification from whole blood, which uses a panel of reactions to detect species-specific non-18S rRNA gene targets. A pan-Plasmodium18S rRNA target is also amplified to allow species identification or confirmation by sequencing if necessary. An evaluation of assay accuracy, performed on 76 clinical samples (56 positives using thin smear microscopy as the reference method and 20 negatives), demonstrated clinical sensitivities of 95.2% forP. falciparum(20/21 positives detected) and 100% for thePlasmodiumgenus (52/52),P. vivax(20/20),P. ovale(9/9), andP. malariae(6/6). The sensitivity of theP. knowlesi-specific PCR was evaluated using spiked whole blood samples (100% [10/10 detected]). The specificities of the real-time PCR primers were 94.2% forP. vivax(49/52) and 100% forP. falciparum(51/51),P. ovale(62/62),P. malariae(69/69), andP. knowlesi(52/52). Thirty-three specimens were used to test species identification by sequencing the pan-Plasmodium18S rRNA PCR product, with correct identification in all cases. The real-time PCR assay also identified two samples with mixedP. falciparumandP. ovaleinfection, which was confirmed by sequencing. The assay described here can be integrated into a malaria testing algorithm in low-prevalence areas, allowing definitivePlasmodiumspecies identification shortly after malaria diagnosis by microscopy.
10
Osagiede, Nicholas Osazuyi, H. C. Yayock, and J. Ndife. "MOLECULAR DETECTION OF THE PLASMODIUM FALCIPARUM OBTAINED FROM OUT-PATIENTS FROM SELECTED HOSPITALS IN KADUNA STATE." FUDMA JOURNAL OF SCIENCES 6, no. 1 (April 11, 2022): 351–57. http://dx.doi.org/10.33003/fjs-2022-0601-698.
Full textAbstract:
Molecular detection of Plasmodium falciparum based on PCR amplification is generally very specific and sensitive test for determining the species of Plasmodium present in the blood of an individual than the microscopy-based diagnosis from blood smears. Thirty-two (32) microscopic malaria positive blood samples were collected from some patients between November 2013 to March 2014 from three major hospitals.Plasmodium DNA was extracted from the 32 blood samples collected from the malaria-positive patients confirmed by microscopy and the DNA amplification was done by using Polymerase Chain Reaction (PCR). The amplified COX3 gene of each malaria isolates were further characterized using Agarose gel electrophoresis while sequence identification was performed by using GenBank’s BLAST algorithm. After the completion of the agarose gel electrophoresis the bands indicating amplified Cox3 gene by PCR was observed in four (4) plasmodium positive blood samples out of the 32 samples analyzed. Amplified band for COX3 gene was located at 300bp position on the DNA ladder on the agarose gel plate for sample 1, 9 and 24 all from Kagarko general hospital while sample 28 was from GwannaAwan general hospital. The BLAST results showed that the P. falciparum DNA sequences aligned at 98-99% similarity with those deposited in the GenBank confirming the parasite isolated from the patients were P. falciparum. The use of PCR diagnosis to compliment microscopy examination of stained blood smears in our medical centres is strongly recommended so that an accurate detection of malaria parasites in blood will help to institute proper drug therapy
11
Bacon, David J., Andrea M. McCollum, Sean M. Griffing, Carola Salas, Valeria Soberon, Meddly Santolalla, Ryan Haley, et al. "Dynamics of Malaria Drug Resistance Patterns in the Amazon Basin Region following Changes in Peruvian National Treatment Policy for Uncomplicated Malaria." Antimicrobial Agents and Chemotherapy 53, no. 5 (March 2, 2009): 2042–51. http://dx.doi.org/10.1128/aac.01677-08.
Full textAbstract:
ABSTRACT Monitoring changes in the frequencies of drug-resistant and -sensitive genotypes can facilitate in vivo clinical trials to assess the efficacy of drugs before complete failure occurs. Peru changed its national treatment policy for uncomplicated malaria to artesunate (ART)-plus-mefloquine (MQ) combination therapy in the Amazon basin in 2001. We genotyped isolates collected in 1999 and isolates collected in 2006 to 2007 for mutations in the Plasmodium falciparum dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) genes, multidrug resistance gene 1 (Pfmdr-1), the chloroquine (CQ) resistance transporter gene (Pfcrt), and the Ca2+ ATPase gene (PfATP6); these have been shown to be involved in resistance to sulfadoxine-pyrimethamine (SP), MQ, CQ, and possibly ART, respectively. Microsatellite haplotypes around the Pfdhfr, Pfdhps, Pfcrt, and Pfmdr-1 loci were also determined. There was a significant decline in the highly SP resistant Pfdhfr and Pfdhps genotypes from 1999 to 2006. In contrast, a CQ-resistant Pfcrt genotype increased in frequency during the same period. Among five different Pfmdr-1 allelic forms noted in 1999, two genotypes increased in frequency while one genotype decreased by 2006. We also noted previously undescribed polymorphisms in the PfATP6 gene as well as an increase in the frequency of a deletion mutant during this period. In addition, microsatellite analysis revealed that the resistant Pfdhfr, Pfdhps, and Pfcrt genotypes have each evolved from a single founder haplotype, while Pfmdr-1 genotypes have evolved from at least two independent haplotypes. Importantly, this study demonstrates that the Peruvian triple mutant Pfdhps genotypes are very similar to those found in other parts of South America.
12
Adamu, Al-Mukhtar Yahuza, Olayeni Stephen Olonitola, Helen Ileigo Inabo, and Ahmad Babangida Suleiman. "Detection of antimalarial drug resistance polymorphisms in Plasmodium falciparum chloroquine resistance transporter and Plasmodium falciparum multidrug resistance 1 genes of Plasmodium falciparum found in Kano State, Nigeria." Calabar Journal of Health Sciences 5 (June 30, 2021): 8–14. http://dx.doi.org/10.25259/cjhs_14_2020.
Full textAbstract:
Objectives: In 2018, malaria claimed an estimated 380,000 lives in African region, with Nigeria accounting for 24.0% (91,368) of malaria deaths from the region. Mutations in Plasmodium falciparum chloroquine resistance transporter (Pfcrt) and P. falciparum multidrug resistance 1 (Pfmdr-1) genes had reduced the effective use of artemisinin combination therapy through the development of resistance to these antimalarial agents. Our study set out to determine the antimalarial drug resistance polymorphisms in Pfcrt and Pfmdr-1 genes of P. falciparum isolates among patients in Kano State, Nigeria. Material and Methods: Malaria positive samples were collected across the three senatorial districts of Kano State. The samples were amplified using nested polymerase chain reaction to detect the Pfcrt and Pfmdr-1 genes. The amplicons were sequenced and bioinformatic analysis was done using CLC Sequence viewer 8.0 and BioEdit sequence alignment editor to detect the single-nucleotide polymorphisms. Results: In the Pfcrt gene, CVIET haplotype was seen in 26.2% of the samples while only two samples showed the 86Y mutation in the Pfmdr-1 gene. All the 86Y mutations and majority of the CVIET haplotypes were detected in the patients from rural settings where some of them noted that they consumed modern and traditional (herbs) antimalarial agents. One sample was observed to have the CVIET haplotype and N86Y mutation while the other five CVIET haplotypes were seen in five separate samples. A new mutation V62A was found in the Pfmdr-1 gene as observed in one of the sample. Conclusion: It is imperative to ensure the rational use of the right antimalarial agents and employ continuous resistance surveillance/mapping to ensure synergy in malaria containment and elimination strategies.
13
Teoh, Jian-peng, Kyoung-mi Park, Zuzana Broskova, Felix R. Jimenez, Ahmed S. Bayoumi, Krystal Archer, Huabo Su, et al. "Identification of gene signatures regulated by carvedilol in mouse heart." Physiological Genomics 47, no. 9 (September 2015): 376–85. http://dx.doi.org/10.1152/physiolgenomics.00028.2015.
Full textAbstract:
Chronic treatment with the β-blocker carvedilol has been shown to reduce established maladaptive left ventricle (LV) hypertrophy and to improve LV function in experimental heart failure. However, the detailed mechanisms by which carvedilol improves LV failure are incompletely understood. We previously showed that carvedilol is a β-arrestin-biased β1-adrenergic receptor ligand, which activates cellular pathways in the heart independent of G protein-mediated second messenger signaling. More recently, we have demonstrated by microRNA (miR) microarray analysis that carvedilol upregulates a subset of mature and pre-mature miRs, but not their primary miR transcripts in mouse hearts. Here, we next sought to identify the effects of carvedilol on LV gene expression on a genome-wide basis. Adult mice were treated with carvedilol or vehicle for 1 wk. RNA was isolated from LV tissue and hybridized for microarray analysis. Gene expression profiling analysis revealed a small group of genes differentially expressed after carvedilol treatment. Further analysis categorized these genes into pathways involved in tight junction, malaria, viral myocarditis, glycosaminoglycan biosynthesis, and arrhythmogenic right ventricular cardiomyopathy. Genes encoding proteins in the tight junction, malaria, and viral myocarditis pathways were upregulated in the LV by carvedilol, while genes encoding proteins in the glycosaminoglycan biosynthesis and arrhythmogenic right ventricular cardiomyopathy pathways were downregulated by carvedilol. These gene expression changes may reflect the molecular mechanisms that underlie the functional benefits of carvedilol therapy.
14
Mairet-Khedim, Mélissa, Flore Nardella, Nimol Khim, Saorin Kim, Nimol Kloeung, Sopheakvatey Ke, Chhayleang Kauy, et al. "In vitro activity of ferroquine against artemisinin-based combination therapy (ACT)-resistant Plasmodium falciparum isolates from Cambodia." Journal of Antimicrobial Chemotherapy 74, no. 11 (September 13, 2019): 3240–44. http://dx.doi.org/10.1093/jac/dkz340.
Full textAbstract:
Abstract Background Cambodia is the epicentre of resistance emergence for virtually all antimalarial drugs. Selection and spread of parasites resistant to artemisinin-based combination therapy (ACT) is a major threat for malaria elimination, hence the need to renew the pool of effective treatments. Objectives To determine whether ACT resistance haplotypes could have an effect on ferroquine in vitro antimalarial activity. Methods In vitro susceptibility to ferroquine was measured for 80 isolates from Cambodia characterized for their molecular resistance profile to artemisinin, piperaquine and mefloquine. Results Among the 80 isolates tested, the overall median (IQR) IC50 of ferroquine was 10.9 nM (8.7–18.3). The ferroquine median (IQR) IC50 was 8.9 nM (8.1–11.8) for Pfk13 WT parasites and was 12.9 nM (9.5–20.0) for Pfk13 C580Y parasites with no amplification of Pfpm2 and Pfmdr1 genes. The median (IQR) IC50 of ferroquine for Pfk13 C580Y parasites with amplification of the Pfpm2 gene was 17.2 nM (14.5–20.5) versus 9.1 nM (7.9–10.7) for Pfk13 C580Y parasites with amplification of the Pfmdr1 gene. Conclusions Ferroquine exerts promising efficacy against ACT-resistant isolates. Whereas Pfpm2 amplification was associated with the highest parasite tolerance to ferroquine, the susceptibility range observed was in accordance with those measured in ACT resistance-free areas. This enables consideration of ferroquine as a relevant therapeutic option against ACT-resistant malaria.
15
Kpemasse, Augustin, Fortune Dagnon, Ramani Saliou, Alexis Sacca Yarou Maye, Cyriaque Dossou Affoukou, Alassane Zoulkaneri, Blaise Guézo-Mévo, et al. "Efficacy of Artemether-Lumefantrine for the Treatment of Plasmodium falciparum Malaria in Bohicon and Kandi, Republic of Benin, 2018–2019." American Journal of Tropical Medicine and Hygiene 105, no. 3 (September 15, 2021): 670–76. http://dx.doi.org/10.4269/ajtmh.21-0086.
Full textAbstract:
ABSTRACT. In 2005, artemether-lumefantrine (AL), an artemisinin-based combination therapy, was introduced as the first-line treatment of uncomplicated Plasmodium falciparum malaria in Benin. Per World Health Organization recommendations to monitor the efficacy of antimalarial treatment, we conducted a therapeutic efficacy study with AL for uncomplicated P. falciparum malaria in Bohicon and Kandi, Benin, from 2018 to 2019. Febrile patients aged 6 to 59 months with confirmed P. falciparum monoinfection received supervised doses of AL for 3 days. We monitored patients clinically and parasitologically on days 1, 2, 3, 7, 14, 21, and 28. A molecular analysis to detect mutations in the P. falciparum Kelch propeller gene (Pfk13) gene was carried out on day 0 samples. A total of 205 patients were included in the study. In Bohicon, the uncorrected adequate clinical and parasitological response (ACPR) proportion was 91.3% (95% confidence interval [CI]: 84.6–95.8%), whereas in Kandi this proportion was 96.7% (95% CI: 90.6–99.3%). Genotype-corrected ACPR proportions were 96.3% (95% CI: 90.9–99.0%) and 96.7% (95% CI: 90.6–99.3%) in Bohicon and Kandi, respectively. On day 3, 100% of patients in Bohicon and 98.9% of patients in Kandi had undetectable parasitemia. The C580Y mutation in the Pfk13 gene was not observed. AL remains effective for P. falciparum malaria in these two sites in Benin. Monitoring antimalarial efficacy and prevalence of molecular-resistance markers in Benin should be continued to allow for early detection of antimalarial resistance and to guide treatment policies.
16
Ducati, Rodrigo G., Hilda A. Namanja-Magliano, Rajesh K. Harijan, J. Eduardo Fajardo, Andras Fiser, Johanna P. Daily, and Vern L. Schramm. "Genetic resistance to purine nucleoside phosphorylase inhibition in Plasmodium falciparum." Proceedings of the National Academy of Sciences 115, no. 9 (February 12, 2018): 2114–19. http://dx.doi.org/10.1073/pnas.1525670115.
Full textAbstract:
Plasmodium falciparum causes the most lethal form of human malaria and is a global health concern. The parasite responds to antimalarial therapies by developing drug resistance. The continuous development of new antimalarials with novel mechanisms of action is a priority for drug combination therapies. The use of transition-state analog inhibitors to block essential steps in purine salvage has been proposed as a new antimalarial approach. Mutations that reduce transition-state analog binding are also expected to reduce the essential catalytic function of the target. We have previously reported that inhibition of host and P. falciparum purine nucleoside phosphorylase (PfPNP) by DADMe-Immucillin-G (DADMe-ImmG) causes purine starvation and parasite death in vitro and in primate infection models. P. falciparum cultured under incremental DADMe-ImmG drug pressure initially exhibited increased PfPNP gene copy number and protein expression. At increased drug pressure, additional PfPNP gene copies appeared with point mutations at catalytic site residues involved in drug binding. Mutant PfPNPs from resistant clones demonstrated reduced affinity for DADMe-ImmG, but also reduced catalytic efficiency. The catalytic defects were partially overcome by gene amplification in the region expressing PfPNP. Crystal structures of native and mutated PfPNPs demonstrate altered catalytic site contacts to DADMe-ImmG. Both point mutations and gene amplification are required to overcome purine starvation induced by DADMe-ImmG. Resistance developed slowly, over 136 generations (2136 clonal selection). Transition-state analog inhibitors against PfPNP are slow to induce resistance and may have promise in malaria therapy.
17
Humphreys, G. S., I. Merinopoulos, J. Ahmed, C. J. M. Whitty, T. K. Mutabingwa, C. J. Sutherland, and R. L. Hallett. "Amodiaquine and Artemether-Lumefantrine Select Distinct Alleles of the Plasmodium falciparum mdr1 Gene in Tanzanian Children Treated for Uncomplicated Malaria." Antimicrobial Agents and Chemotherapy 51, no. 3 (December 28, 2006): 991–97. http://dx.doi.org/10.1128/aac.00875-06.
Full textAbstract:
ABSTRACT The artemisinin-based combination therapies artemether-lumefantrine (AL) and amodiaquine (AQ) plus artesunate have been adopted for treatment of Plasmodium falciparum malaria in many African countries. Molecular markers of parasite resistance suitable for surveillance have not been established for any of the component drugs in either of these combinations. We assessed P. falciparum mdr1 (Pfmdr1) alleles present in 300 Tanzanian children presenting with uncomplicated falciparum malaria, who were enrolled in a clinical trial of antimalarial therapy. Pfmdr1 genotype analysis was also performed with isolates from 182 children who failed AQ monotherapy and 54 children who failed AL treatment. Pfmdr1 alleles 86Y, 184Y, and 1246Y were more common among treatment failures in the AQ group than among pretreatment infections. The converse was found in the AL-treated group. Children presenting with the 86Y/184Y/1246Y Pfmdr1 haplotype and treated with AQ were significantly more likely to retain this haplotype if they were parasite positive during posttreatment follow-up than were children treated with AL (odds ratio, 33.25; 95% confidence interval, 4.17 to 1441; P, <0.001). We conclude that AL and AQ exert opposite within-host selective effects on the Pfmdr1 gene of P. falciparum.
18
Rouault, Tracey. "Ferroportin in Erythrocytes: Importance for Iron Homeostasis and its Role in Infection." Blood 134, Supplement_1 (November 13, 2019): SCI—27—SCI—27. http://dx.doi.org/10.1182/blood-2019-121071.
Full textAbstract:
Ferroportin (FPN), the only known vertebrate iron exporter, transports iron from intestinal, splenic, and hepatic cells into the blood to provide iron to other tissues and cells in vivo. Most of the circulating iron is consumed by erythroid cells to synthesize hemoglobin. Recently, we found that erythroid cells not only consume large amounts of iron, but also return significant amounts of iron to the blood. Erythroblast-specific Fpn knockout (Fpn KO) mice developed lower serum iron levels in conjunction with tissue iron overload and increased FPN expression in spleen and liver without changing hepcidin levels. Our results also showed that Fpn KO mice, which suffer from mild hemolytic anemia, were sensitive to phenylhydrazine-induced oxidative stress but were able to tolerate iron deficiency upon exposure to a low-iron diet and phlebotomy, supporting that the anemia of Fpn KO mice resulted from erythrocytic iron overload and resulting oxidative injury rather than a red blood cell (RBC) production defect. Moreover, we found that the mean corpuscular volume (MCV) values of gain-of-function FPN mutation patients were positively associated with serum transferrin saturations, whereas MCVs of loss-of-function FPN mutation patients were not, supporting that erythroblasts donate iron to blood through FPN in response to serum iron levels. Our results indicate that FPN of erythroid cells has an unexpectedly essential role in maintaining systemic iron homeostasis and protecting RBCs from oxidative stress, providing insight into the pathophysiology of FPN diseases. When malaria parasites invade red blood cells (RBCs), they consume copious amounts of hemoglobin, and severely disrupt iron regulation in humans. Anemia often accompanies malaria disease; however, iron supplementation therapy inexplicably exacerbates malarial infections. We recently found that the iron exporter ferroportin (FPN) was highly abundant in RBCs, and iron supplementation suppressed its activity. Conditional deletion of the Fpn gene in erythroid cells resulted in accumulation of excess intracellular iron, cellular damage, hemolysis, and increased fatality in malaria-infected mice. In humans, a prevalent FPN mutation,Q248H (glutamine to histidine at position 248), prevented hepcidin-induced degradation of FPN and protected against severe malaria disease. FPNQ248H appears to have been positively selected in African populations in response to the impact of malaria disease. Thus, FPN protects RBCs against oxidative stress and malaria infection. Zhang DL, Wu J, Shah BN et al. Erythrocytic ferroportin reduces intracellular iron accumulation, hemolysis, and malaria risk. Science. 2018;359 (6383):1520-1523. Zhang DL, Ghosh MC, Ollivierre H, Li Y, Rouault TA. Ferroportin deficiency in erythroid cells causes serum iron deficiency and promotes hemolysis due to oxidative stress. Blood. 2018;132 (19):2078-2087. Zhang DL, Rouault TA. How does hepcidin hinder ferroportin activity. Blood. 2018;131 (8):840-842. Disclosures No relevant conflicts of interest to declare.
19
Maiga, Hamma, Anastasia Grivoyannis, Issaka Sagara, Karim Traore, Oumar B. Traore, Youssouf Tolo, Aliou Traore, et al. "Selection of pfcrt K76 and pfmdr1 N86 Coding Alleles after Uncomplicated Malaria Treatment by Artemether-Lumefantrine in Mali." International Journal of Molecular Sciences 22, no. 11 (June 3, 2021): 6057. http://dx.doi.org/10.3390/ijms22116057.
Full textAbstract:
Background: Artemether-lumefantrine is a highly effective artemisinin-based combination therapy that was adopted in Mali as first-line treatment for uncomplicated Plasmodium falciparum malaria. This study was designed to measure the efficacy of artemether-lumefantrine and to assess the selection of the P. falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multi-drug resistance 1 (pfmdr1) genotypes that have been associated with drug resistance. Methods: A 28-day follow-up efficacy trial of artemether-lumefantrine was conducted in patients aged 6 months and older suffering from uncomplicated falciparum malaria in four different Malian areas during the 2009 malaria transmission season. The polymorphic genetic markers MSP2, MSP1, and Ca1 were used to distinguish between recrudescence and reinfection. Reinfection and recrudescence were then grouped as recurrent infections and analyzed together by PCR-restriction fragment length polymorphism (RFLP) to identify candidate markers for artemether-lumefantrine tolerance in the P. falciparum chloroquine resistance transporter (pfcrt) gene and the P. falciparum multi-drug resistance 1 (pfmdr1) gene. Results: Clinical outcomes in 326 patients (96.7%) were analyzed and the 28-day uncorrected adequate clinical and parasitological response (ACPR) rate was 73.9%. The total PCR-corrected 28-day ACPR was 97.2%. The pfcrt 76T and pfmdr1 86Y population prevalence decreased from 49.3% and 11.0% at baseline (n = 337) to 38.8% and 0% in patients with recurrent infection (n = 85); p = 0.001), respectively. Conclusion: Parasite populations exposed to artemether-lumefantrine in this study were selected toward chloroquine-sensitivity and showed a promising trend that may warrant future targeted reintroduction of chloroquine or/and amodiaquine.
20
Bierhaus, A., Ch J. Hemmer, N. Mackman, R. Kutob, R. Ziegler, M. Dietrich, and P. P. Nawroth. "Antiparasitic Treatment of Patients with P. falciparum Malaria Reduces the Ability of Patient Serum to Induce Tissue Factor by Decreasing NF-κB Activation." Thrombosis and Haemostasis 73, no. 01 (1995): 039–48. http://dx.doi.org/10.1055/s-0038-1653723.
Full textAbstract:
SummarySerum from patients with P. falciparum malaria at day 1 (pretherapy) induces tissue factor (TF) in cultured endothelial cells. TF induction depends on de novo transcription as shown in Nuclear Run On assays. Electrophoretic mobility shift assays demonstrated binding of AP-1 and NF- κB/Rel proteins to their recognition sites in the TF promotor. After therapy (day 28), stimulation of TF antigen by patient serum is reduced by 70%. When serum obtained before and after therapy was compared, a decrease of NF-κB activation was evident. Activation of NF-κB-like proteins was in part dependent on TNFα in patient serum, since a TNFα neutralizing antibody reduced induction of TF transcription and translation and induction of NF-κB-like proteins. Induction of TF activity was suppressed by pDTC, an inhibitor of NF-κB activation. When different promotor constructs of the TF gene were tested, induction was dependent upon the presence of the intact NF-κB-like binding site in the TF promotor. A mutant with deleted NF-κB, but intact AP-1 sites was not inducible. Mutation of the AP-1 sites did not prevent induction, but reduced inducibility by pretherapy serum. Therefore, NF-κB/Rel proteins are responsible for induction of TF transcription by pretherapy serum, but AP-1 is needed for highest inducibility. The effect of antiparasitic therapy on the induction of TF by serum from patients with complicated P. falciparum malaria is dependent on a therapy-mediated loss of activation of NF-κB-like proteins in post-treatment patient serum.
21
Dokomajilar, Christian, Samuel L. Nsobya, Bryan Greenhouse, Philip J. Rosenthal, and Grant Dorsey. "Selection of Plasmodium falciparum pfmdr1 Alleles following Therapy with Artemether-Lumefantrine in an Area of Uganda where Malaria Is Highly Endemic." Antimicrobial Agents and Chemotherapy 50, no. 5 (May 2006): 1893–95. http://dx.doi.org/10.1128/aac.50.5.1893-1895.2006.
Full textAbstract:
ABSTRACT Polymorphisms in the Plasmodium falciparum pfmdr1 gene were assayed in pretreatment samples and in samples from patients reinfected following therapy with artemether-lumefantrine. The pfmdr1 alleles 86N, 184F, and 1246D significantly increased in prevalence after treatment. All samples had a single pfmdr1 copy. Treatment with artemether-lumefantrine selects for polymorphisms that may alter antimalarial drug response.
22
Rodrigues, Louise A., Gisela Henriques, Sofia T. Borges, Paul Hunt, Cecília P. Sanchez, Axel Martinelli, and Pedro Cravo. "Experimental Evolution of Resistance to Artemisinin Combination Therapy Results in Amplification of the mdr1 Gene in a Rodent Malaria Parasite." PLoS ONE 5, no. 7 (July 15, 2010): e11593. http://dx.doi.org/10.1371/journal.pone.0011593.
Full text
23
Witmer, Kathrin, Farah A. Dahalan, Michael J. Delves, Sabrina Yahiya, Oliver J. Watson, Ursula Straschil, Darunee Chiwcharoen, et al. "Transmission of Artemisinin-Resistant Malaria Parasites to Mosquitoes under Antimalarial Drug Pressure." Antimicrobial Agents and Chemotherapy 65, no. 1 (November 2, 2020): e00898-20. http://dx.doi.org/10.1128/aac.00898-20.
Full textAbstract:
ABSTRACTResistance to artemisinin-based combination therapy (ACT) in the Plasmodium falciparum parasite is threatening to reverse recent gains in reducing global deaths from malaria. While resistance manifests as delayed parasite clearance in patients, the phenotype can only spread geographically via the sexual stages and mosquito transmission. In addition to their asexual killing properties, artemisinin and its derivatives sterilize sexual male gametocytes. Whether resistant parasites overcome this sterilizing effect has not, however, been fully tested. Here, we analyzed P. falciparum clinical isolates from the Greater Mekong Subregion, each demonstrating delayed clinical clearance and known resistance-associated polymorphisms in the Kelch13 (PfK13var) gene. As well as demonstrating reduced asexual sensitivity to drug, certain PfK13var isolates demonstrated a marked reduction in sensitivity to artemisinin in an in vitro male gamete formation assay. Importantly, this same reduction in sensitivity was observed when the most resistant isolate was tested directly in mosquito feeds. These results indicate that, under artemisinin drug pressure, while sensitive parasites are blocked, resistant parasites continue transmission. This selective advantage for resistance transmission could favor acquisition of additional host-specificity or polymorphisms affecting partner drug sensitivity in mixed infections. Favored resistance transmission under ACT coverage could have profound implications for the spread of multidrug-resistant malaria beyond Southeast Asia.
24
Broyles, Robert H., Visar Belegu, Austin C. Roth, Emily J. Curry, Robert A. Floyd, Sonia Levi, Paolo Arosio, Paolo Santambrogio, Marie Trudel, and Sunil K. Joshi. "Ferritin-H and a Phytotherapeutic, Alone or Combined, Reprogram RBC Precursor Cells From SCD Patients to Produce Levels of Fetal Hemoglobin That Constitute a Phenotypic Cure for Sickle Cell As Well As Providing Resistance to Malaria and a Probable Treatment for Beta-Thalassemia." Blood 118, no. 21 (November 18, 2011): 903. http://dx.doi.org/10.1182/blood.v118.21.903.903.
Full textAbstract:
Abstract Abstract 903 OBJECTIVE: To test the phenotypic cure we have discovered for SCD and malaria in vivo in mice and in vitro in human red blood cell precursors from SCD patients in two-phase cultures. BACKGROUND: Gene regulation of developmental hemoglobin switching provides phenotypic cures for beta thalassemias, sickle cell disease, and malaria since it is known that reactivation of fetal globin expression alleviates all these disorders. We discovered a protein that regulates this developmental switch. Ferritin heavy chain (FtH) represses adult β-globin and activates γ(fetal)-globin gene expression in embryonic/K562 erythroid cells (Broyles et al., PNAS98: 9145, 2001; US Patents #7,517,669, #7,718,669, & #2009/0232783 A1; EU Patent # EP1354032B1; Australia patent #2002217964), leading us to propose FtH as a therapeutic agent. METHODS: Normal C57BL/6 mice, transgenics carrying the complete human beta-globin gene cluster (Beta-YAC Tg), and transgenic mice that express human FtH in definitive erythroid cells have been used under an IACUC-approved protocol to show the safety and efficacy of human FtH and our phytotherapeutic in vivo. Erythroid precursor cells from pediatric SCD patients obtained under an IRB-approved protocol and cultured in a two-phase system allow direct testing of an FtH expression plasmid, FtH protein, and our phytotherapeutic for manipulating Hb phenotypes. Hemoglobins were identified and quantified by HPLC; fetal Hb was confirmed by immunofluorescence. RESULTS AND DISCUSSION: Human FtH transgenic mice, in which the FtH gene is driven by a truncated b-promoter lacking the FtH-binding motif, express human FtH in definitive erythroid cells which results in repression of bMajor-globin but not bMinor-globin. Thus, these TgFtH mice are born with a reduced ratio of bMajor/bMinor globins, resulting in α-globin chain excess and a mild b-thalassemia. In applying this therapy to humans, thalassemia would not be expected since FtH also activates g (fetal)-globin, preventing the chain imbalance. Recent results with normal mice and Beta-YacTg mice show that FtH protein and our phytotherapeutic are both well tolerated in vivo. We have used numbers of target cells (found in the FtH transgenics) as an initial screen for determining an effective dosing regimens. Initial results indicate that both therapeutics are altering the Hb phenotype as predicted. With cultured erythroid precursor cells from the pediatric SCD patients, our results show a complete switch from HbS to HbF with each mode of delivery of FtH or the phytotherapeutic. These results were replicated 15 times using cells from 9 SCD donors, as well as in erythroid precursors from normal donors. Human erythroid precursor cells have surface receptors specific for FtH. Immunofluorescence showed that human FtH is taken into the precursor cells in culture; and confocal microscopy confirmed nuclear localization of exogenously applied FtH. These results suggest that the purified protein and/or the phytotherapeutic can be directly delivered without gene therapy. Therefore, these methods of generating a phenotypic cure for malaria, beta-thal, and SCD should be inexpensive to deliver in vivo. Supported in part by donations to The Sickle Cell Cure Foundation and by a Grand Challenges in Global Health grant from the Bill & Melinda Gates Foundation. Disclosures: No relevant conflicts of interest to declare.
25
Too, Edwin, Rahma Udu, Francis Kimani, Benard Osero, and Omar Sabah. "Effectiveness of Artemether Lumefantrine and Dihydroartemisinin Piperaquine in Clearance of Gametocytes in Uncomplicated Plasmodium falciparum Malaria in Tiwi Kenya." East Africa Science 4, no. 1 (March 31, 2022): 71–77. http://dx.doi.org/10.24248/easci.v4i1.61.
Full textAbstract:
Background: Over 80 countries worldwide have now implemented WHO recommendations to use Artemisinin-Based Combination Therapy as a first-line treatment for Plasmodium falciparum malaria. The sexual stage of P. falciparum is responsible for the transmission of malarial parasites to infectious mosquitoes. Studies on gametocytes are generally based on microscopic detection, which is not sensitive, and there is a need for more sensitive molecular techniques that can detect and quantify gametocytes at densities as low as 0.02 to 0.1 gametocytes per micro-litre. The objective of this study was to determine the clearance rates of gametocytes after AL and DHA&P in uncomplicated P. falciparum and to compare the effectiveness of microscopy and reverse transcriptase-polymerase chain reaction in gametocyte detection. Methods: In a randomised controlled clinical trial of samples collected, gametocyte densities were quantified by microscopy by counting against 500 leukocytes in the thick smear converted to numbers of parasites per micro-litre by assuming a standard count of 800 leukocytes per micro-litre of blood after staining with 10% Giemsa stain and by reverse transcriptase-polymerase chain reaction using primers specific to the pfs25 gene. Results: There was no significant difference between the drug’s gametocyte clearance (p<.082). The drugs cleared gametocytes in infected patients by day 28 as detected by microscopy. There was a significant difference in the detection of gametocytes by RT-PCR and microscopy (p<.001). Conclusion: This study showed that Artemether-Lumefantrine and Dihydroartemisinin piperaquine have gametocytocidal effects on P. falciparum and the study on the clearance of gametocytes using both artemether-lumefantrine and Dihydroartemisinin piperaquine may be carried out using a larger sample size for policy implementation. The reverse transcriptase-polymerase chain reaction is more effective than microscopy in detecting low levels of gametocytes and the pfs25 gene can be used in the detection of gametocytes in the field to monitor the clearance of gametocytes.
26
Too, Edwin, Rahma Udu, Francis Kimani, Benard Osero, and Omar Sabah. "Effectiveness of Artemether Lumefantrine and Dihydroartemisinin Piperaquine in Clearance of Gametocytes in Uncomplicated Plasmodium falciparum Malaria in Tiwi Kenya." East Africa Science 4, no. 1 (March 31, 2022): 71–77. http://dx.doi.org/10.24248/easci.v4i1.61.
Full textAbstract:
Background: Over 80 countries worldwide have now implemented WHO recommendations to use Artemisinin-Based Combination Therapy as a first-line treatment for Plasmodium falciparum malaria. The sexual stage of P. falciparum is responsible for the transmission of malarial parasites to infectious mosquitoes. Studies on gametocytes are generally based on microscopic detection, which is not sensitive, and there is a need for more sensitive molecular techniques that can detect and quantify gametocytes at densities as low as 0.02 to 0.1 gametocytes per micro-litre. The objective of this study was to determine the clearance rates of gametocytes after AL and DHA&P in uncomplicated P. falciparum and to compare the effectiveness of microscopy and reverse transcriptase-polymerase chain reaction in gametocyte detection. Methods: In a randomised controlled clinical trial of samples collected, gametocyte densities were quantified by microscopy by counting against 500 leukocytes in the thick smear converted to numbers of parasites per micro-litre by assuming a standard count of 800 leukocytes per micro-litre of blood after staining with 10% Giemsa stain and by reverse transcriptase-polymerase chain reaction using primers specific to the pfs25 gene. Results: There was no significant difference between the drug’s gametocyte clearance (p<.082). The drugs cleared gametocytes in infected patients by day 28 as detected by microscopy. There was a significant difference in the detection of gametocytes by RT-PCR and microscopy (p<.001). Conclusion: This study showed that Artemether-Lumefantrine and Dihydroartemisinin piperaquine have gametocytocidal effects on P. falciparum and the study on the clearance of gametocytes using both artemether-lumefantrine and Dihydroartemisinin piperaquine may be carried out using a larger sample size for policy implementation. The reverse transcriptase-polymerase chain reaction is more effective than microscopy in detecting low levels of gametocytes and the pfs25 gene can be used in the detection of gametocytes in the field to monitor the clearance of gametocytes.
27
Saksouk, Nehmé, Micah M. Bhatti, Sylvie Kieffer, Aaron T. Smith, Karine Musset, Jérôme Garin, William J. Sullivan, Marie-France Cesbron-Delauw, and Mohamed-Ali Hakimi. "Histone-Modifying Complexes Regulate Gene Expression Pertinent to the Differentiation of the Protozoan Parasite Toxoplasma gondii." Molecular and Cellular Biology 25, no. 23 (December 1, 2005): 10301–14. http://dx.doi.org/10.1128/mcb.25.23.10301-10314.2005.
Full textAbstract:
ABSTRACT Pathogenic apicomplexan parasites like Toxoplasma and Plasmodium (malaria) have complex life cycles consisting of multiple stages. The ability to differentiate from one stage to another requires dramatic transcriptional changes, yet there is a paucity of transcription factors in these protozoa. In contrast, we show here that Toxoplasma possesses extensive chromatin remodeling machinery that modulates gene expression relevant to differentiation. We find that, as in other eukaryotes, histone acetylation and arginine methylation are marks of gene activation in Toxoplasma. We have identified mediators of these histone modifications, as well as a histone deacetylase (HDAC), and correlate their presence at target promoters in a stage-specific manner. We purified the first HDAC complex from apicomplexans, which contains novel components in addition to others previously reported in eukaryotes. A Toxoplasma orthologue of the arginine methyltransferase CARM1 appears to work in concert with the acetylase TgGCN5, which exhibits an unusual bias for H3 [K18] in vitro. Inhibition of TgCARM1 induces differentiation, showing that the parasite life cycle can be manipulated by interfering with epigenetic machinery. This may lead to new approaches for therapy against protozoal diseases and highlights Toxoplasma as an informative model to study the evolution of epigenetics in eukaryotic cells.
28
Hortua Triana, Miryam Andrea, Daniela Cajiao Herrera, Barbara H. Zimmermann, Barbara A. Fox, and David J. Bzik. "Pyrimidine Pathway-Dependent and -Independent Functions of the Toxoplasma gondii Mitochondrial Dihydroorotate Dehydrogenase." Infection and Immunity 84, no. 10 (August 1, 2016): 2974–81. http://dx.doi.org/10.1128/iai.00187-16.
Full textAbstract:
Dihydroorotate dehydrogenase (DHODH) mediates the fourth step ofde novopyrimidine biosynthesis and is a proven drug target for inducing immunosuppression in therapy of human disease as well as a rapidly emerging drug target for treatment of malaria. InToxoplasma gondii, disruption of the first, fifth, or sixth step ofde novopyrimidine biosynthesis induced uracil auxotrophy. However, previous attempts to generate uracil auxotrophy by genetically deleting the mitochondrion-associated DHODH ofT. gondii(TgDHODH) failed. To further address the essentiality ofTgDHODH, mutant gene alleles deficient inTgDHODH activity were designed to ablate the enzyme activity. Replacement of the endogenousDHODHgene with catalytically deficientDHODHgene alleles induced uracil auxotrophy. Catalytically deficientTgDHODH localized to the mitochondria, and parasites retained mitochondrial membrane potential. These results show thatTgDHODH is essential for the synthesis of pyrimidines and suggest thatTgDHODH is required for a second essential function independent of its role in pyrimidine biosynthesis.
29
Sutherland, Colin J. "Genetic markers of artemisinin resistance in Plasmodium spp. parasites." Emerging Topics in Life Sciences 1, no. 6 (December 22, 2017): 525–31. http://dx.doi.org/10.1042/etls20170100.
Full textAbstract:
The vast majority of malaria patients worldwide are currently treated with combination therapy comprising one of the artemisinin family of drugs, characterised by rapid action and short plasma half-life, co-formulated with a longer-lasting drug from the amino aryl-alcohol or quinoline families. There is now a widely perceived threat to treatment efficacy, as reduced susceptibility to rapid artemisinin clearance in vivo has become prevalent among populations of Plasmodium falciparum in the Greater Mekong subregion since 2008. In vitro and in vivo drug selection studies, heterologous cell expression experiments and genetic epidemiology have identified many candidate markers of reduced ring-stage susceptibility to artemisinin. Certain variants of the P. falciparum pfk13 gene, which encodes a kelch domain protein implicated in the unfolded protein response, are strongly associated with slow parasite clearance by artemisinin in the Mekong subregion. However, anomalies in the epidemiological association of pfk13 variants with true treatment failure in vivo and the curious cell-cycle stage specificity of this phenotype in vitro warrant exploration in some depth. Taken together, available data suggest that the emergence of P. falciparum expressing K13 variants has not yet precipitated a public health emergency. Alternative candidate markers of artemisinin susceptibility are also described, as K13-independent treatment failure has been observed in African P. falciparum and in the rodent malaria parasite Plasmodium chabaudi.
30
Zhao, Le, Yunhao Zhu, Haoyu Jia, Yongguang Han, Xiaoke Zheng, Min Wang, and Weisheng Feng. "From Plant to Yeast—Advances in Biosynthesis of Artemisinin." Molecules 27, no. 20 (October 14, 2022): 6888. http://dx.doi.org/10.3390/molecules27206888.
Full textAbstract:
Malaria is a life-threatening disease. Artemisinin-based combination therapy (ACT) is the preferred choice for malaria treatment recommended by the World Health Organization. At present, the main source of artemisinin is extracted from Artemisia annua; however, the artemisinin content in A. annua is only 0.1–1%, which cannot meet global demand. Meanwhile, the chemical synthesis of artemisinin has disadvantages such as complicated steps, high cost and low yield. Therefore, the application of the synthetic biology approach to produce artemisinin in vivo has magnificent prospects. In this review, the biosynthesis pathway of artemisinin was summarized. Then we discussed the advances in the heterologous biosynthesis of artemisinin using microorganisms (Escherichia coli and Saccharomyces cerevisiae) as chassis cells. With yeast as the cell factory, the production of artemisinin was transferred from plant to yeast. Through the optimization of the fermentation process, the yield of artemisinic acid reached 25 g/L, thereby producing the semi-synthesis of artemisinin. Moreover, we reviewed the genetic engineering in A. annua to improve the artemisinin content, which included overexpressing artemisinin biosynthesis pathway genes, blocking key genes in competitive pathways, and regulating the expression of transcription factors related to artemisinin biosynthesis. Finally, the research progress of artemisinin production in other plants (Nicotiana, Physcomitrella, etc.) was discussed. The current advances in artemisinin biosynthesis may help lay the foundation for the remarkable up-regulation of artemisinin production in A. annua through gene editing or molecular design breeding in the future.
31
Yuan, Lili, Ying Wang, Daniel M. Parker, Bhavna Gupta, Zhaoqing Yang, Huaie Liu, Qi Fan, et al. "Therapeutic Responses of Plasmodium vivax Malaria to Chloroquine and Primaquine Treatment in Northeastern Myanmar." Antimicrobial Agents and Chemotherapy 59, no. 2 (December 15, 2014): 1230–35. http://dx.doi.org/10.1128/aac.04270-14.
Full textAbstract:
ABSTRACTChloroquine-primaquine (CQ-PQ) continues to be the frontline therapy for radical cure ofPlasmodium vivaxmalaria. Emergence of CQ-resistant (CQR)P. vivaxparasites requires a shift to artemisinin combination therapies (ACTs), which imposes a significant financial, logistical, and safety burden. Monitoring the therapeutic efficacy of CQ is thus important. Here, we evaluated the therapeutic efficacy of CQ-PQ forP. vivaxmalaria in northeast Myanmar. We recruited 587 patients withP. vivaxmonoinfection attending local malaria clinics during 2012 to 2013. These patients received three daily doses of CQ at a total dose of 24 mg of base/kg of body weight and an 8-day PQ treatment (0.375 mg/kg/day) commencing at the same time as the first CQ dose. Of the 401 patients who finished the 28-day follow-up, the cumulative incidence of recurrent parasitemia was 5.20% (95% confidence interval [CI], 3.04% to 7.36%). Among 361 (61%) patients finishing a 42-day follow-up, the cumulative incidence of recurrent blood-stage infection reached 7.98% (95% CI, 5.20% to 10.76%). The cumulative risk of gametocyte carriage at days 28 and 42 was 2.21% (95% CI, 0.78% to 3.64%) and 3.93% (95% CI, 1.94% to 5.92%), respectively. Interestingly, for all 15 patients with recurrent gametocytemia, this was associated with concurrent asexual stages. Genotyping of recurrent parasites at the merozoite surface protein 3α gene locus from 12 patients with recurrent parasitemia within 28 days revealed that 10 of these were the same genotype as at day 0, suggesting recrudescence or relapse. Similar studies in 70 patients in the same area in 2007 showed no recurrent parasitemias within 28 days. The sensitivity to chloroquine ofP. vivaxin northeastern Myanmar may be deteriorating.
32
Yusuf, Rahma Udu, Sabah Ahmed Omar, and Raphael Muchangi Ngure. "The effect of Point Mutations in Dihydrofolate reductase genes and Multidrug resistance gene 1-86 on treatment of falciparum malaria in Sudan." Journal of Infection in Developing Countries 4, no. 02 (November 21, 2009): 061–69. http://dx.doi.org/10.3855/jidc.630.
Full textAbstract:
Background: One of the major problems to the treatment of malaria is the emergence and spread of parasite resistant to antimalarial drugs. Due to increased chloroquine (CQ) resistance, the antifolate combinations are becoming important in the chemotherapy of falciparum malaria. However, resistance to antifolate exists and they are still effective in the above combinations. This study aimed at determining the prevalence of antimalarial drug resistance markers in P. falciparum isolates, involving the detection of mutations at the mdr 1- 86 which associates with amodiaquine resistance, and dhfr mutations associated with SP resistances. Methods: The dot-blot/ probe hybridization, which is more sensitive and specific; it detects parasitaemia of less than 100 parasites/µl of blood, and can identify a minority parasite genotype down to 1% in a mixture, was adopted to determine multi-drug resistance (mdr1-86) to show the correlation of Amodiaquine (AQ) resistance and PCR/ RFLP adopted to determine dihydrofolate reductase (dhfr) baseline resistance to Sulphadoxine- Pyrimethamine (SP) resistance in Nubian region of southern Sudan. A randomized open label trial of Artesunate (AS) + SP and AS+ SP was carried out in children less than 5 years. Molecular analysis of filter paper preserved blood samples collected was carried out to provide a baseline estimate of allele prevalences. Results: Baseline of the allele prevalence of the mdr1 86 locus in the AS+ AQ was successful for 80 isolates: 71(8.11%) carried parasites harbouring the mdr1-86 Tyr resistance allele, while 7 (89.19%) carried mdr1-86 Asn sensitivity allele and 2 (2.7%) were of mixed infection, having both resistance and wild type allele. Overall, the prevalence of the dhfr point mutation, codon 51, 59 and 108: 82.5% (132/160) carried mutations at dhfr (N51I, C59R or S108N), but triple mutants were rare (3.1%) in the AS + SP arm. Conclusion: The research provides the evidence that mutations present in dhfr and mdr1 86 has a significant effect on the type of treatment following SP and AQ chemotherapy. SP resistance may spread rapidly, and AS + AQ is likely to be a better option, provided AQ use is restricted to the combination. The significance of the study shows that definitely combination of drugs improves SP therapy at the study site. Keywords: Antimalarial drugs, P. falciparum, dhfr, mdr-1, dot-blot hybridisation technique, PCR/RFLP
33
Moyeh, Marcel N., Dieudonne L. Njimoh, Marie Solange Evehe, Innocent M. Ali, Akindeh M. Nji, Dominique N. Nkafu, Palmer N. Masumbe, Atogho-Tiedeu Barbara, Valentine N. Ndikum, and Wilfred F. Mbacham. "Effects of Drug Policy Changes on Evolution of Molecular Markers of Plasmodium falciparum Resistance to Chloroquine, Amodiaquine, and Sulphadoxine-Pyrimethamine in the South West Region of Cameroon." Malaria Research and Treatment 2018 (May 2, 2018): 1–7. http://dx.doi.org/10.1155/2018/7071383.
Full textAbstract:
Background. As a result of the spread of parasites resistant to antimalarial drugs, Malaria treatment guidelines in Cameroon evolved from nonartemisinin monotherapy to artemisinin-based combination therapy. The aim of this study was to assess the effect of these therapy changes on the prevalence of molecular markers of resistance from 2003 to 2013 in Mutengene, Cameroon. Methodology. Dry blood samples (collected in 2003–2005 and 2009–2013) were used for parasite DNA extraction. Drug resistance genes were amplified by PCR and hybridized with oligonucleotide probes or subjected to restriction digestion. The prevalence of individual marker polymorphisms and haplotypes was compared in these two study periods using the Chi square test. Results. Alleles conferring resistance to 4-aminoquinolines in the Pfcrt 76T and Pfmdr1 86Y, 184F, and 1246Y genotypes showed a significant reduction of 97.0% to 66.9%, 83.6% to 45.2%, 97.3% to 56.0%, and 3.1% to 0.0%, respectively (P<0.05). No difference was observed in SNPs associated with antifolate drugs resistance 51I, 59R, 108N, or 540E (P>0.05). Haplotype analysis in the Pfmdr1 gene showed a reduction in the YFD from 75.90% to 42.2%, P<0.0001, and an increase in the NYD (2.9% to 30.1%; P<0.0001). Conclusions. The results indicated a gradual return of the 4-aminoquinoline sensitive genotype while the antifolate resistant genotypes increased to saturation.
34
Alsamman, Alsamman M., and Hatem Zayed. "The transcriptomic profiling of SARS-CoV-2 compared to SARS, MERS, EBOV, and H1N1." PLOS ONE 15, no. 12 (December 10, 2020): e0243270. http://dx.doi.org/10.1371/journal.pone.0243270.
Full textAbstract:
The SARS-CoV-2 (COVID-19) pandemic is a global crisis that threatens our way of life. As of November 18, 2020, SARS-CoV-2 has claimed more than 1,342,709 lives, with a global mortality rate of ~2.4% and a recovery rate of ~69.6%. Understanding the interaction of cellular targets with the SARS-CoV-2 infection is crucial for therapeutic development. Therefore, the aim of this study was to perform a comparative analysis of transcriptomic signatures of infection of SARS-CoV-2 compared to other respiratory viruses (EBOV, H1N1, MERS-CoV, and SARS-CoV), to determine a unique anti-SARS-CoV-2 gene signature. We identified for the first time that molecular pathways for heparin-binding, RAGE, miRNA, and PLA2 inhibitors were associated with SARS-CoV-2 infection. The NRCAM and SAA2 genes, which are involved in severe inflammatory responses, and the FGF1 and FOXO1 genes, which are associated with immune regulation, were found to be associated with the cellular gene response to SARS-CoV-2 infection. Moreover, several cytokines, most significantly IL-8 and IL-6, demonstrated key associations with SARS-CoV-2 infection. Interestingly, the only response gene that was shared among the five viral infections was SERPINB1. The protein-protein interaction (PPI) analysis shed light on genes with high interaction activity that SARS-CoV-2 shares with other viral infections. The findings showed that the genetic pathways associated with rheumatoid arthritis, the AGE-RAGE signaling system, malaria, hepatitis B, and influenza A were of high significance. We found that the virogenomic transcriptome of infection, gene modulation of host antiviral responses, and GO terms of SARS-CoV-2 and EBOV were more similar than to SARS, H1N1, and MERS. This work compares the virogenomic signatures of highly pathogenic viruses and provides valid targets for potential therapy against SARS-CoV-2.
35
Delandre, Océane, Mathieu Gendrot, Isabelle Fonta, Joel Mosnier, Nicolas Benoit, Rémy Amalvict, Nicolas Gomez, Marylin Madamet, and Bruno Pradines. "Prevalence of Mutations in the pfcoronin Gene and Association with Ex Vivo Susceptibility to Common Quinoline Drugs against Plasmodium falciparum." Pharmaceutics 13, no. 8 (August 17, 2021): 1273. http://dx.doi.org/10.3390/pharmaceutics13081273.
Full textAbstract:
Background: Artemisinin-based combination therapy (ACT) was recommended to treat uncomplicated falciparum malaria. Unlike the situation in Asia where resistance to ACT has been reported, artemisinin resistance has not yet emerged in Africa. However, some rare failures with ACT or patients continuing to be parasitaemic on day 3 after ACT treatment have been reported in Africa or in travellers returning from Africa. Three mutations (G50E, R100K, and E107V) in the pfcoronin gene could be responsible for artemisinin resistance in Africa. Methods: The aims of this study were first to determine the prevalence of mutations in the pfcoronin gene in African P. falciparum isolates by Sanger sequencing, by targeting the 874 samples collected from patients hospitalised in France after returning from endemic areas in Africa between 2018 and 2019, and secondly to evaluate their association with in vitro reduced susceptibility to standard quinoline antimalarial drugs, including chloroquine, quinine, mefloquine, desethylamodiaquine, lumefantrine, piperaquine, and pyronaridine. Results: The three mutations in the pfcoronin gene (50E, 100K, and 107V) were not detected in the 874 P. falciparum isolates. Current data show that another polymorphism (P76S) is present in many countries of West Africa (mean prevalence of 20.7%) and Central Africa (11.9%) and, rarely, in East Africa (4.2%). This mutation does not appear to be predictive of in vitro reduced susceptibility to quinolines, including artemisinin derivative partners in ACT such as amodiaquine, lumefantrine, piperaquine, pyronaridine, and mefloquine. Another mutation (V62M) was identified at low prevalence (overall prevalence of 1%). Conclusions: The 76S mutation is present in many African countries with a prevalence above 10%. It is reassuring that this mutation does not confer in vitro resistance to ACT partners.
36
McMorran, Brendan John, Clare M. Smith, Ante Jerkovic, Hervé Puy, Ingrid Winship, Jean-Charles Deybach, Laurent Gouya, et al. "Erythropoietic Protoporphyric Red Blood Cells Are Resistant to the Growth of Malarial Parasites." Blood 124, no. 21 (December 6, 2014): 2670. http://dx.doi.org/10.1182/blood.v124.21.2670.2670.
Full textAbstract:
Abstract Many red cell polymorphisms are a result of selective pressure by the malarial parasite. Here we add another red cell disease to the panoply of erythrocytic changes that give rise to resistance to malaria. Erythrocytes from individuals with erythropoietic protoporphyria (EPP) have low levels of the final enzyme in the heme biosynthetic pathway, ferrochelatase. Cells from these patients are resistant to the growth of the human malarial parasite, Plasmodium falciparum. We first compared the growth and replication rates of P. falciparum cultured in red cells from EPP patients (n=4) and normal erythrocytes. There was a two to three-fold reduction in parasite growth in the patient cells. Next we sought to exclude the possible negative effects on the parasite due to elevated porphyrins and reduced cell hemoglobin. To do this we employed the EPP phenocopy, X-linked dominant protoporphyria (XLDPP), which has normal ferrochelatase activity. Cells from three individuals with XLDPP supported completely normal rates of parasite growth, proving that the EPP resistance phenomenon was due to the absence of ferrochelatase. We also tested the requirement of host ferrochelatase during malarial infection by using mice with a hypomorphic mutation in the murine ferrochelatase gene and the rodent malarial species, P. chabaudi. Mice homozygous for the mutation, Fechm1Pas, have 5% residual ferrochelatase activity compared to wild-type littermates 1. Following infection, we observed an almost two fold reduction in peak parasitemia levels and two to three times greater rates of survival in the homozygous mice. Host ferrochelatase is therefore also necessary to sustain a normal malarial infection in mice. To determine the requirement of parasite-expressed ferrochelase, we produced a P. berghei parasite line carrying a complete deletion of the ferrochelatase gene. This strain grew normally in wild-type mouse erythrocytes, indicating that parasite ferrochelatase is dispensable during the erythrocytic stage of infection. A complete absence of ferrochelatase in humans (and mice) is not compatible with life, and therefore testing parasite growth in complete knockout cells was not possible. Instead, we used a specific competitive inhibitor of the enzyme, N-methylprotoporphyrin (NMPP) to eliminate all ferrochelatase activity from the parasite and red cell. Treatment of P. falciparum cultures with NMPP resulted in potent cytocidal and growth inhibition effects against both antimalarial drug-sensitive and drug-resistant parasite lines. The activity of NMPP could be competitively removed by titration of the ferrochelatase substrate, protoporphyrin IX, proving that the effects of NMPP were due to specific enzyme inhibition and not off-target effects. Therefore ferrochelatase activity is also essential for the Plasmodium parasite. We conclude that the refractoriness of ferrochelatse-deficient red cells to Plasmodium is due to the parasite’s reliance on the host enzyme. Host ferrochelatase is probably utilized by the parasite for the biosynthesis of heme. In support of this hypothesis, others have observed that red cell ferrochelatase is imported by intraerythrocytic Plasmodium and enzymatic is retained 2,3. Finally, based on this collective data, we propose human ferrochelatase is a valid and novel “host-directed” target for an antimalarial therapy. Lyoumi S, Abitbol M, Andrieu V, et al. Increased plasma transferrin, altered body iron distribution, and microcytic hypochromic anemia in ferrochelatase-deficient mice. Blood. 2007;109(2):811-818.Bonday ZQ, Dhanasekaran S, Rangarajan PN, Padmanaban G. Import of host delta-aminolevulinate dehydratase into the malarial parasite: identification of a new drug target. Nat Med. 2000;6(8):898-903.Varadharajan S, Sagar BK, Rangarajan PN, Padmanaban G. Localization of ferrochelatase in Plasmodium falciparum. Biochem J. 2004;384(Pt 2):429-436. Disclosures No relevant conflicts of interest to declare.
37
Ekwattanakit, Supachai, Jiraporn Korchuenjit, Thidarat Suksangpleng, Suchada Riolueang, Tana Taechalertpaisarn, Parichat Prommana, Pakatip Silapamongkolkul, et al. "An Unexpectedly High Frequency of Sptb Gene Mutation (SPTB exon 29: c.6055T>C (p.Ser2019Pro; Spectrin Thai)) with a Single Origin in Thailand Suggesting a New Model of Red Blood Cell Trait Against Malarial Pressure." Blood 132, Supplement 1 (November 29, 2018): 2322. http://dx.doi.org/10.1182/blood-2018-99-110982.
Full textAbstract:
Abstract Mutations in SPTB gene coding β-spectrin can lead to congenital hemolytic anemia (HA) or red cell membranopathy. Most patients presented with mild to moderate HA with either spherocytes or ovalo-elliptocytes. Only one report in the literature described a family with non-immune hydrops fetalis (HF) due to homozygous SPTB: c.6055T>C (p.Ser2019Pro). Recently, we have identified the second patient presented with HF in Thailand with the same genotypes through genomic approach. This finding has driven extensive study to determine the impact of SPTB mutation in our cohort of unexplained HA and HF. From 107,947 live births at our center between 2005 and 2016, 83 non-immune HF were identified. Nineteen cases from 42 unexplained HF (45%) had FFPE DNA available from autopsy (Fig 1). In addition, 7 patients who were transfusion dependent anemia due to unknown cause were recruited. These were subjects of our Whole Exome Analysis (WES) using Illumina HiSeq4000 capturing by SureSelect V5 plus UTR covering 21,522 genes. Moreover, we studied WES in 120 Thai individuals without anemia as controls. Surprisingly, 6 out of 26 patients (23%) were homozygous SPTB: c.6055T>C and none in controls. We confirmed this finding by direct genomic Sanger sequencing and set up a PCR-RFLP to detect this further in other cohorts. Interestingly, we found additional 13 heterozygotes of this mutation in our thalassemia patients (1 in 361) and general population (12 in 2,576) (Fig 1) making an unexpectedly high carrier rate of this "so-called rare genetic disease" into 0.47% in Thai population. Using Hardy-Weinberg principle, homozygous SPTB: c.6055T>C would be 5.42 per million or expected 358 cases in Thailand. Since most reported SPTB mutations are sporadic or familial specific, we wondered whether this affected allele has a single or multiple origins. We generated a haplotype analysis of SPTB on chromosome 14q23 using 23 informative SNPs at the gene locus and adjacent region from WES data. Total 23 different haplotypes were generated and the SPTB c.6055T>C originated from the same ancestral chromosome as it was found only in haplotype IA (Fig 2). Therefore, we proposed to name this as spectrin Thai, instead of spectrin Providence which was named after the place of the first case reported (Gallagher PG, et al. J Clin Invest 1995), but not related to its native population. All 4 survived patients due to homozygous spectrin Thai (one received intrauterine transfusion) had severe anemia at birth and neonatal jaundice requiring therapy and became transfusion dependent afterward. All had marked hepatosplenomegaly with blood picture of pyropoikilocytosis. Three patients underwent splenectomy without improvement on anemia, this finding contradicted those in patients with red cell membranopathies. Of note, hematology from 25 heterozygotes including 12 parents showed no apparently abnormal indices and normal EMA binding assay. Using shortgun proteomics to analyze red cell membrane proteins, hemolysate and plasma proteins, the only difference was we could detect unbound free β-spectrin in plasma from controls but not from spectrin Thai traits. This might be useful for future screening of heterozygotes at population level. To explore whether red cells with spectrin Thai trait has any protection against malaria, the most important selective pressure in the past of our region we studied in vitro growth of P. falciparum and kinetics of erythroid invasion using live-cell microscopy. We found no significant differences between normal and spectrin Thai traits on these aspects. Since β-spectrin is involved on knob formation of malarial infected red cells that plays an important role on sequestration and cerebral manifestation, a further study using scanning electron microscopy comparing between malarial infected normal against spectrin Thai red cells is underway. For the first time, we showed that red cell membranopathy might be endemic in the tropics than we expected. Homozygous spectrin Thai is one of the most common causes of unexplained HF and HA in our region. The possibility that red cell membranopathy traits might be under malarial pressure throughout human history has completed the whole red cell quantitative trait genetic polymorphism in our population. This is in consistent with those of hemoglobinopathy (thalassemia) and enzymopathy (G6PD), both are highly prevalent in our region due to the same biological advantage against malaria. Disclosures Viprakasit: Agios: Consultancy, Research Funding; Protagonist Therapeutics: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Research Funding.
38
Akingbola, Titilola S., Santosh L. Saraf, Binal N. Shah, Chinedu Anthony Ezekekwu, Omowunmi Sonubi, Lewis L. Hsu, Richard S. Cooper, Victor R. Gordeuk, and Bamidele O. Tayo. "Hydroxyurea for Treatment of Sickle Cell Disease in Adults in Africa." Blood 128, no. 22 (December 2, 2016): 1305. http://dx.doi.org/10.1182/blood.v128.22.1305.1305.
Full textAbstract:
Abstract Background: The vast majority of births with sickle cell disease (SCD) occur in Africa and 90% are thought to die before the age of five. Hydroxyurea (HU) is the only drug approved by the FDA for the treatment of sickle cell anemia. Although HU is used to treat a small number of patients in Africa, cost, fear of toxicity, and lack of awareness and availability limit its use. Methods: We prospectively assigned 31 high risk sickle cell anemia patients (hemoglobin F <8.6%, no alpha globin gene deletion, BCL11A rs1427407 GG, rs7606173 CC) to fixed low dose HU (500 mg/day) for six months and monitored the development of cytopenias and new or recurrent malaria or tuberculosis. Malaria prophylaxis was given with proguanil 200 mg po daily. Nine patients did not come regularly for monthly supplies of HU and we report on 22 patients who received medication five or six months out of the prospective six-month period. Picking up refills was the only metric for adherence to daily hydroxyurea in the study. Results: The median (range) age of the patients was 24 (18-42) years and 7 (32%) were females. The median (range) dose per body weight of HU was 9.9 (7.0-13.7) mg/kg per day. Hemoglobin F was measured at baseline and during HU therapy in 15 patients and showed a mean increase of 4.7% (P=0.0001). There were mean increases in the mean corpuscular volume (MCV) of 12.1 fL, in hemoglobin of 0.8 g/L and in hematocrit of 3.3% during low dose HU therapy (P<0.0001). There were mean decreases in the white blood cell (WBC) count of 1700/uL, in absolute neutrophil count (ANC) of 1,300/uL and in platelet count of 112,000/uL. Body weight increased by a mean of 0.9 kg (P=0.030). No patient developed the predetermined toxicities of ANC <500 per uL or platelets <50,000 per uL. The lowest ANC observed was 2500 and the lowest platelet count was 76,000, which returned to >150,000 with continued therapy. One patient developed active tuberculosis while on HU therapy and another patient died of hyperhemolytic crisis two months after completing HU therapy. Conclusion: Our results support the concept that low dose HU can be administered in the African setting with salutary features of gain in body weight, increase in hemoglobin concentration and lowering of the WBC count but absence of dangerous cytopenias. However, they raise the concern that such therapy might increase the risk of recrudescent tuberculosis. We propose that a larger prospective multicenter study including urban and rural areas should be organized to document the role of fixed low dose HU in adults with SCD in Africa. Figure Hemoglobin, MCV and Hematocrit increased progressively and during the first three months (A-C) and then did not change significantly during the second three months. WBC, platelets and ANC decreased progressively during the first three months (D-F) and then did not change significantly during the second three months. Figure. Hemoglobin, MCV and Hematocrit increased progressively and during the first three months (A-C) and then did not change significantly during the second three months. WBC, platelets and ANC decreased progressively during the first three months (D-F) and then did not change significantly during the second three months. Disclosures Hsu: Centers for Medicare and Medicaid Innovation: Research Funding; EMMI Solutions: Consultancy; Sancilio: Research Funding; Astra Zeneca: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Eli Lilly: Research Funding; Gerson Lehman Group: Consultancy; Mast Therapeutics: Research Funding; Hilton Publishing: Consultancy, Research Funding; Purdue Pharma: Research Funding.
39
Ahmed, Anwar, Deepak Bararia, Sumiti Vinayak, Mohammed Yameen, Sukla Biswas, Vas Dev, Ashwani Kumar, Musharraf A. Ansari, and Yagya D. Sharma. "Plasmodium falciparum Isolates in India Exhibit a Progressive Increase in Mutations Associated with Sulfadoxine-Pyrimethamine Resistance." Antimicrobial Agents and Chemotherapy 48, no. 3 (March 2004): 879–89. http://dx.doi.org/10.1128/aac.48.3.879-889.2004.
Full textAbstract:
ABSTRACT The combination of sulfadoxine-pyrimethamine (SP) is used as a second line of therapy for the treatment of uncomplicated chloroquine-resistant Plasmodium falciparum malaria. Resistance to SP arises due to certain point mutations in the genes for the dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS) enzymes of the parasite. We have analyzed these mutations in 312 field isolates of P. falciparum collected from different parts of India to assess the effects of drug pressure. The rate of mutation in the gene for DHFR was found to be higher than that in the gene for DHPS, although the latter had mutations in more alleles. There was a temporal rise in the number of isolates with double dhfr mutations and single dhps mutations, resulting in an increased total number of mutations in the loci for DHFR and DHPS combined over a 5-year period. During these 5 years, the number of isolates with drug-sensitive genotypes decreased and the number of isolates with drug-resistant genotypes (double DHFR mutations and a single DHPS mutation) increased significantly. The number of isolates with the triple mutations in each of the genes for the two enzymes (for a total of six mutations), however, remained very low, coinciding with the very low rate of SP treatment failure in the country. There was a regional bias in the mutation rate, as isolates from the northeastern region (the state of Assam) showed higher rates of mutation and more complex genotypes than isolates from the other regions. It was concluded that even though SP is prescribed as a second line of treatment in India, the mutations associated with SP resistance continue to be progressively increasing.
40
Mohamed, Tamer M. A., Simon A. Zakeri, Florence Baudoin, Markus Wolf, Delvac Oceandy, Elizabeth J. Cartwright, Sheraz Gul, and Ludwig Neyses. "Optimisation and Validation of a High Throughput Screening Compatible Assay to Identify Inhibitors of the Plasma Membrane Calcium ATPase Pump - a Novel Therapeutic Target for Contraception and Malaria." Journal of Pharmacy & Pharmaceutical Sciences 16, no. 2 (May 22, 2013): 217. http://dx.doi.org/10.18433/j3pg68.
Full textAbstract:
Purpose. ATPases, which constitute a major category of ion transporters in the human body, have a variety of significant biological and pathological roles. However, the lack of high throughput assays for ATPases has significantly limited drug discovery in this area. We have recently found that the genetic deletion of the ATP dependent calcium pump PMCA4 (plasma membrane calcium/calmodulin dependent ATPase, isoform 4) results in infertility in male mice due to a selective defect in sperm motility. In addition, recent discoveries in humans have indicated that a single nucleotide polymorphism (SNP) in the PMCA4 gene determines the susceptibility towards malaria plasmodium infection. Therefore, there is an urgent need to develop specific PMCA4 inhibitors. In the current study, we aim to optimise and validate a high throughput screening compatible assay using recombinantly expressed PMCA4 and the HTRF® Transcreener® ADP (TR-FRET) assay to screen a drug library. Methods and Results. PMCA4 membrane microsomes were prepared from HEK293 cells overexpressing PMCA4. Western blot quantification revealed nearly nine-fold increased expression of PMCA4 compared to LacZ (control virus)-infected cells. Maximal PMCA4 microsomal activity was achieved in the TR-FRET assay with 15ng/μl microsomal concentration, 30-minute pre-incubation with compounds at 37°C, and calcium buffering with 1mM EGTA providing 1μM free-calcium. Finally a dose-response curve for carboxyeosin (a non-specific PMCA inhibitor) under optimised conditions showed significant PMCA4 inhibition. Upon confirmation that the assay was suitable for high-throughput screening, we have screened the ChemBioNet small molecule library (~21,000 compounds) against the PMCA4 assay to identify those that are its apparent inhibitors. This screening yielded 1,494 primary hits. Conclusions. We have optimised the HTRF® Transcreener® ADP assay for high-throughput screening to identify PMCA4 inhibitors. The output of the screening campaign has provided preliminary chemical starting points that could be further developed to specific PMCA4 inhibitors for non-hormonal contraception or anti-malaria therapy.
This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.
41
Lin, Sharon S. J., Shawn L. Fultz, Amy C. Justice, Richard Bucala, K. Gary J. Vanasse, and Nancy Berliner. "The Role of Macrophage Migration Inhibitory Factor (MIF) Genetic Polymorphisms in Predicting the Development of Macrocytic Anemia in HIV+ Patients." Blood 108, no. 11 (November 16, 2006): 1254. http://dx.doi.org/10.1182/blood.v108.11.1254.1254.
Full textAbstract:
Abstract Anemia is the most common hematologic morbidity in HIV+ patients and is associated with increased mortality. In previous studies, we have examined anemia-associated mortality in over 30,000 HIV+ men cared for within the VA system, and have confirmed the increased mortality previously shown to be associated with anemia. Most strikingly, however, we have demonstrated that macrocytosis in particular is an independent risk factor for early mortality even after correcting for alcohol abuse, liver disease, or therapy with AZT. We hypothesize that macrocytosis reflects a proinflammatory state associated with HIV and magnified by co-morbidities. We have therefore sought to link anemia with known markers of underlying inflammation. Genetic variants that affect the level of cytokine gene expression have been shown to influence the development of anemia associated with a variety of illnesses. One such polymorphism occurs in the macrophage migration inhibitory factor (MIF) gene, a cytokine secreted by macrophages and T-cells that induces release of TNF and IL-6 from macrophages. Our group has defined two polymorphisms in the promoter of the human MIF gene that affect the level of MIF expression. The first, a tetranucleotide CATT repeat, occurs 5-8 times within a Pit-1transcription factor binding site, and increased numbers of repeats are associated with higher levels of MIF expression. The second, a single-nucleotide polymorphism (SNP), has been identified at −173 bp (G/C), although its significance in predicting cytokine levels has been hard to separate from the associated CATT repeat polymorphism. High expression MIF polymorphisms have been shown to correlate with the development of anemia in the setting of malaria, to influence recovery from community acquired pneumonia, and to increase the severity of manifestations of rheumatoid arthritis. We therefore undertook to examine whether MIF polymorphisms might influence the development of anemia in the setting of HIV. We wished to test the hypothesis that the presence of high-expressing alleles of MIF predisposes to the development of anemia in the setting of HIV, particularly in association with other co-morbid conditions. In order to address this question, genomic DNA isolated/extracted from blood collected as part of the Veterans Aging Cohort Study (VACS) has been genotyped for the polymorphisms using a PCR based method. These data are being correlated with anemia, mean corpuscular volume, and CD4 count. We are using Cox proportional hazards models stratified by age, race, HIV severity, and co-morbid disease to examine associations between anemia type/severity and MIF gene polymorphisms. We are currently analyzing the prevalence of high-expressing MIF alleles in non-anemic and anemic patients with and without HIV, using multivariate analysis to identify correlations of genotype with markers of morbidity. It is hoped that these studies will provide insight into the etiology of anemia in HIV+ patients in general, and of macrocytic anemia in particular.
42
Fiscon, Giulia, Federica Conte, Lorenzo Farina, and Paola Paci. "SAveRUNNER: A network-based algorithm for drug repurposing and its application to COVID-19." PLOS Computational Biology 17, no. 2 (February 5, 2021): e1008686. http://dx.doi.org/10.1371/journal.pcbi.1008686.
Full textAbstract:
The novelty of new human coronavirus COVID-19/SARS-CoV-2 and the lack of effective drugs and vaccines gave rise to a wide variety of strategies employed to fight this worldwide pandemic. Many of these strategies rely on the repositioning of existing drugs that could shorten the time and reduce the cost compared to de novo drug discovery. In this study, we presented a new network-based algorithm for drug repositioning, called SAveRUNNER (Searching off-lAbel dRUg aNd NEtwoRk), which predicts drug–disease associations by quantifying the interplay between the drug targets and the disease-specific proteins in the human interactome via a novel network-based similarity measure that prioritizes associations between drugs and diseases locating in the same network neighborhoods. Specifically, we applied SAveRUNNER on a panel of 14 selected diseases with a consolidated knowledge about their disease-causing genes and that have been found to be related to COVID-19 for genetic similarity (i.e., SARS), comorbidity (e.g., cardiovascular diseases), or for their association to drugs tentatively repurposed to treat COVID-19 (e.g., malaria, HIV, rheumatoid arthritis). Focusing specifically on SARS subnetwork, we identified 282 repurposable drugs, including some the most rumored off-label drugs for COVID-19 treatments (e.g., chloroquine, hydroxychloroquine, tocilizumab, heparin), as well as a new combination therapy of 5 drugs (hydroxychloroquine, chloroquine, lopinavir, ritonavir, remdesivir), actually used in clinical practice. Furthermore, to maximize the efficiency of putative downstream validation experiments, we prioritized 24 potential anti-SARS-CoV repurposable drugs based on their network-based similarity values. These top-ranked drugs include ACE-inhibitors, monoclonal antibodies (e.g., anti-IFNγ, anti-TNFα, anti-IL12, anti-IL1β, anti-IL6), and thrombin inhibitors. Finally, our findings were in-silico validated by performing a gene set enrichment analysis, which confirmed that most of the network-predicted repurposable drugs may have a potential treatment effect against human coronavirus infections.
43
Wamae, Kevin, Leonard Ndwiga, Oksana Kharabora, Kelvin Kimenyi, Victor Osoti, Zaydah de Laurent, Juliana Wambua, et al. "Targeted Amplicon deep sequencing of ama1 and mdr1 to track within-host P. falciparum diversity throughout treatment in a clinical drug trial." Wellcome Open Research 7 (March 16, 2022): 95. http://dx.doi.org/10.12688/wellcomeopenres.17736.1.
Full textAbstract:
Antimalarial therapeutic efficacy studies are routinely conducted in malaria-endemic countries to assess the effectiveness of antimalarial treatment strategies. Targeted amplicon deep sequencing (TADS) uniquely identifies and quantifies genetically distinct parasites within an infection. In this study, TADS Plasmodium falciparum apical membrane antigen 1 (ama1), and multidrug resistance gene 1 (mdr1), were used to characterize the complexity of infection (COI) and drug-resistance genotypes, respectively. P. falciparum positive samples were obtained from a triple artemisinin combination therapy clinical trial conducted in 30 children under 13 years of age between 2018 and 2019 in Kilifi, Kenya. Of the 30 participants, 9 presented with recurrent parasitemia from day 26 (624h) onwards. The ama1 and mdr1 genes were amplified and sequenced, while msp1, msp2 and glurp data were obtained from the original clinical study. The COI was comparable between ama1 and msp1, msp2 and glurp, however, overall ama1 detected more haplotypes. Based on ama1, a stable number of haplotypes were detected throughout treatment up until day 3. Additionally, a recrudescent infection was identified with an ama1 haplotype initially observed at 30h and later in an unscheduled follow-up visit. Using the relative frequencies of ama1 haplotypes and parasitaemia, we identified a fast (<1h) and slow (>5h) clearing haplotype. As expected, only two mdr1 haplotypes (NF and NY) were identified based on the combination of amino acid polymorphisms at codons 86 and 184. This study highlights TADS as a sensitive tool for tracking parasite haplotypes throughout treatment and can detect variation in haplotype clearance estimates. TADS can also identify slow clearing haplotypes, a potential early sign of selection during treatment. Consequently, TADS has the capability of improving the discriminatory power to accurately distinguish recrudescences from reinfections.
44
Wamae, Kevin, Leonard Ndwiga, Oksana Kharabora, Kelvin Kimenyi, Victor Osoti, Zaydah de Laurent, Juliana Wambua, et al. "Targeted amplicon deep sequencing of ama1 and mdr1 to track within-host P. falciparum diversity throughout treatment in a clinical drug trial." Wellcome Open Research 7 (December 15, 2022): 95. http://dx.doi.org/10.12688/wellcomeopenres.17736.2.
Full textAbstract:
Introduction: Antimalarial therapeutic efficacy studies are routinely conducted in malaria-endemic countries to assess the effectiveness of antimalarial treatment strategies. Targeted amplicon sequencing (AmpSeq) uniquely identifies and quantifies genetically distinct parasites within an infection. In this study, AmpSeq of Plasmodium falciparum apical membrane antigen 1 (ama1), and multidrug resistance gene 1 (mdr1), were used to characterise the complexity of infection (COI) and drug-resistance genotypes, respectively. Methods: P. falciparum-positive samples were obtained from a triple artemisinin combination therapy clinical trial conducted in 30 children under 13 years of age between 2018 and 2019 in Kilifi, Kenya. Nine of the 30 participants presented with recurrent parasitemia from day 26 (624h) onwards. The ama1 and mdr1 genes were amplified and sequenced, while msp1, msp2 and glurp data were obtained from the original clinical study. Results: The COI was comparable between ama1 and msp1, msp2 and glurp; overall, ama1 detected more microhaplotypes. Based on ama1, a stable number of microhaplotypes were detected throughout treatment until day 3. Additionally, a recrudescent infection was identified with an ama1 microhaplotype initially observed at 30h and later in an unscheduled follow-up visit. Using the relative frequencies of ama1 microhaplotypes and parasitemia, we identified a fast (<1h) and slow (>5h) clearing microhaplotype. As expected, only two mdr1 microhaplotypes (NF and NY) were identified based on the combination of amino acid polymorphisms at codons 86 and 184. Conclusions: This study highlights AmpSeq as a tool for highly-resolution tracking of parasite microhaplotypes throughout treatment and can detect variation in microhaplotype clearance estimates. AmpSeq can also identify slow-clearing microhaplotypes, a potential early sign of selection during treatment. Consequently, AmpSeq has the capability of improving the discriminatory power to distinguish recrudescences from reinfections accurately.
45
Coetzer, Theresa L., and Sonja B. Lauterbach. "Safety of Total Therapy III for Newly Diagnosed Multiple Myeloma: Preliminary Analysis of 62 Consecutive Patients. Safety of Total Therapy III for Newly Diagnosed Multiple Myeloma: Preliminary Analysis of 62 Consecutive Patients." Blood 104, no. 11 (November 16, 2004): 1582. http://dx.doi.org/10.1182/blood.v104.11.1582.1582.
Full textAbstract:
Abstract Malaria is one of the world’s major health problems, causing millions of deaths every year, primarily in Africa. The disease is caused by Plasmodium parasites, which invade and destroy human erythrocytes. Of the four species infecting humans, Plasmodium falciparum is responsible for the greatest morbidity and mortality burden. The erythrocyte membrane plays a vital role in all aspects of the pathogenic phase of the parasite’s life cycle and the protein-protein interactions between host and parasite are a key focus of research. Spectrin is the main structural protein in the erythrocyte membrane skeleton and phage-display technology was used to probe the interaction between P falciparum peptide fragments and human erythrocyte spectrin. A phage-display library was constructed by isolating mRNA from P falciparum strain FCR-3, which was reverse transcribed using two-base anchored oligodT primers. Linkers facilitating directional cloning were added to the cDNA, followed by insertion into a gene encoding the 10B capsid protein of the T7 bacteriophage vector. The vector was packaged into viral particles and the library amplified using Escherichia coli as a host. The presence and size of inserts were determined by PCR amplification with T7 bacteriophage vector arm specific primers. Human erythrocyte membranes were prepared from whole blood by hypotonic lysis and spectrin was extracted with a low ionic strength buffer and purified by size exclusion chromatography. The protein was biotinylated, immobilized on streptavidin-coated magnetic beads and biopanned against the phage library. Bound phage were eluted and amplified in E coli for three additional rounds of biopanning to eliminate non-specific protein-protein interactions. The P falciparum cDNA inserts of interacting phage were sequenced and compared to the PlasmoDB database. One of the sequences was identified as a putative aminopeptidase (PFI1570c), which has a 30.7% homology to a human aspartyl aminopeptidase, an enzyme catalysing the release of N-terminal amino acids from a peptide. The parasite protein contains a putative transmembrane domain at the C terminal end and is larger than the human form, with an estimated molecular weight of 65 kD. Several features that are critical for enzyme activity are conserved in the P falciparum aminopeptidase. These include twelve amino acids (four histidine, three glutamic acid and five aspartic acid residues), which are involved in the binding of catalytic zinc ions in the active site, as well as a putative N-myristoylation site and phosphorylation sites for casein kinase II and protein kinase C. Interestingly, the peptide fragment that bound to spectrin in the initial phage display screening, corresponds to a 33 amino acid fragment that is not found in the human aspartyl aminopeptidase. This suggests an evolutionary development of the parasite that allows the protease to bind to human spectrin. Mass spectrometry and microarray data from the PlasmoDB database indicate that the protein is present at the erythrocyte membrane and is expressed in all the developmental stages of the parasite’s erythrocytic life cycle. During the trophozoite stage the parasite modifies the erythrocyte membrane to allow transport of nutrients and waste products. The aminopeptidase could cleave spectrin and destabilise the membrane skeleton to facilitate the insertion of parasite protein channels during development. It may also play a role in proteolysis of the skeleton to enable the release of schizonts from infected erythrocytes.
46
Tran, Thuoc Linh, Fuyu Tamanoi, Mong-Hong Lee, and Phuc Van Pham. "Welcome to CRRM2017." Biomedical Research and Therapy 4, S (September 2, 2017): 1. http://dx.doi.org/10.15419/bmrat.v4is.364.
Full textAbstract:
On behalf of the entire the international conference Innovations in Cancer Research and Regenerative Medicine 2017 (CRRM2017) Organizing Committee, we would like to extend to you a warm welcome to Ho Chi Minh city, Vietnam to join the 3rd international conference of CRRM. We are very glad to announce that this time, CRRM has made some exciting changes with more plenary sessions, more sessions, more oral invited speakers and especially a day of pre-conference. With two main topics of cancer research and regenerative medicine, this conference has many sessions organized into some parallel sessions with different topics of cancer research and regenerative medicine. By doing so, the audience can arrange their time for networking and speaking to our commercial partners. From the basic science to clinical trials, all sessions at the conference will cover from gene to human body. Therefore, we believe that every session will provide exciting presentations for attendees at all levels from students to scientists/researchers. With this conference, all authors not only share their latest results, but also can publish their works in the reputed journals. That is a reason why the keywords for this conference is Share & Publish. Like many developing countries, Vietnam has no shortage of health challenges, from infectious diseases such as annual flu epidemics to rising rates of unmet and chronic illnesses such as cancers and diabetes. Vietnam also has to contend with increasing drug resistance for killer diseases including AIDS, tuberculosis, and malaria. There is, however, increasing evidence that Vietnamese researchers are tackling the challenges of harnessing biotechnology to improve health care for healthier society as well as advancing the sciences. The biomedicine progresses in Cancer Research, and Regenerative Medicine in Vietnam include gene diagnostics for genetic disorders of human diseases, infectious pathogens; in-vitro production of therapeutic proteins including insulin, IFNs or biosimilar forms of monoclonal antibodies for targeted therapies; biomaterials; cell therapy; stem cell therapy and tissue engineering. In this conference, with 14 sessions of 100 oral presentations and 100 poster presentations, all latest topics of cancer research and regenerative medicine will be covered. New biomarkers of cancers, immunotherapy strategy for cancers and stem cells as well as tissue engineering are hot topics of CRRM2017. In addition to the conference program, there is an extensive set of pre-conference and lunch-on innovation showcases for on 10th and 11th Sept, respectively. We are very grateful for the support from sponsors for the CRRM2017. More vents will be taking place in the exhibition area, and we encourage attendees to take advantage of the opportunities to visit the exhibit booths and corporate symposia. We wish to thank everyone who helped so enthusiastically in the organization of the conference. Our thanks also go out to all of the speakers who have generously agreed to share their research results and experiences at this conference. We hope that you will enjoy this meeting and have a wonderful time here in Ho Chi Minh city, Vietnam.
47
Zhou, Guangbiao, Ying Liu, and Yongxian Cheng. "Effects of Natural Compound EBSC-26 On Human Multiple Myeloma Cells." Blood 114, no. 22 (November 20, 2009): 4924. http://dx.doi.org/10.1182/blood.v114.22.4924.4924.
Full textAbstract:
Abstract Abstract 4924 Background Human multiple myeloma (MM) is an incurable hematological malignancy at present, and screen for novel therapy remains an urgent need. The objective of this study was to assess the efficacy of natural compound EBSC-26 on multiple myeloma cells. Methods Inhibition of cell growth and proliferation of MM cell lines by compounds were assessed by WST-8 [2-(2-methoxy-4-nitrophenyl)-3-4-nitrophenyl)-5-(2,4- disulfophenyl)-2H-tetrazolium, monosodium salt] which allows sensitive colorimetric assays for the determination of the number of viable cells. Effects of compounds on cell cycle progression were analyzed by using flow cytometry. Apoptosis was evaluated by analysis of Annexin V. Microtubules were detected by immunofluorescence staining and confocal microscopy. Western blot and semi-quantitative/quantitative RT-PCR were performed to test protein/gene expression. Results EBSC-26 with a purity of up to 99.5%, was extracted from Centipeda minima (L.), a compositae plant used for the treatment of cold, nasal allergy, diarrhea, malaria, and asthma in China. We found that EBSC-26 suppressed proliferation/growth of U266, RPMI8226, dexamethasone-sensitive and resistant MM.1 cells, and induced apoptosis of these cells in a dose- and time-dependent manner. It synergized with Bortezomib and Doxorubicin in inhibition of MM cell proliferation. EBSC-26 overcame the protective effects of interleukin-6 and insulin-like growth factor-1 on multiple myeloma cells. It down-regulated interleukin-6-induced phosphorylation of STAT3 and insulin-like growth factor-1-induced phosphorylation of AKT. Moreover, EBSC-26 caused polymerization of microtubules, and induced G2/M arrest MM cells. Interestingly, an important G2/M-phase regulator, cyclin B1 was dramatically increased by EBSC-26 at protein level in a dose-dependent manner. EBSC-26 also decreased the phosphorylation of CDC2 at tyrosine 15. Conclusions These results suggest that EBSC-26 alone may have a potential in the treatment of multiple myeloma, and a combination of this agent with other compounds might provide further benefits. Disclosures No relevant conflicts of interest to declare.
48
Jacob, Seethal A., Yanxia Chu, Enrico M. Novelli, Jeffrey S. Isenberg, Gregory J. Kato, and Yingze Zhang. "Thrombospondin-1 Gene Polymorphism Is Associated with Estimated Pulmonary Artery Pressure in Patients with Sickle Cell Anemia." Blood 126, no. 23 (December 3, 2015): 970. http://dx.doi.org/10.1182/blood.v126.23.970.970.
Full textAbstract:
Abstract Thrombospondin-1 (TSP1) is a multifunctional glycoprotein present in platelet α-granules that contains domains for adhesive proteins, enzymes, and cell receptors. It is released by activated platelets and is increased in the plasma of patients with sickle cell anemia (SCA). TSP1 is known to mediate adherence of sickle reticulocytes to endothelial cells. Furthermore, TSP1 also inhibits the NO signaling pathway through its binding to the CD47 cell receptor on endothelial cells and platelets. Thus, we hypothesized that genetic variants in TSP1 may contribute to the marked phenotypic variation seen in SCA. We tested whether genetic variants of the TSP1 gene are associated with biomarkers of SCA severity and specific complications in a cohort of 452 patients with homozygous HbSS disease from the multicenter walk-PHaSST (Treatment of Pulmonary Hypertension and Sickle Cell Disease with Sildenafil Therapy) trial. Genetic data from 406 patients were included in the analysis. Patients ranged in age from 12 to 70 years, and 51% were females. 307 patients were enrolled at various sites in the United States, while 99 patients were enrolled at Hammersmith Hospital in the UK. A total of 10 SNPs were selected, including haplotype tagged SNPs, coding variants, and SNPs potentially regulating gene expression and alternative splicing. DNA isolated from peripheral blood was used for genotyping. We found that the TSP1 SNPs rs1478604 and rs1478605 were significantly positively correlated with tricuspid regurgitation velocity (TRV) >2.5 m/sec, an echocardiographic marker of pulmonary hypertension associated with increased mortality, under a recessive model (r=0.10, p=0.0288 and r=0.13, p=0.0047 respectively). TRV was also analyzed as a categorical variable using regression analysis, and subjects were grouped based on the following clinically relevant cut-off points, 2.5 m/sec, 2.7 m/sec, and 3 m/sec. Univariate regression analyses showed TRV>2.5 m/sec was independently associated with the recessive genotypes of rs1478604 and rs1478605 (p=0.069 and 0.017 respectively). As previously published, we confirmed the association of TRV with age, gender, NT-proBNP and creatinine, and we adjusted for these variables in multivariate regression analyses for the association of TRV and each SNP. The results showed that the two SNPs were significantly associated with TRV>2.5 m/sec (rs1478604, OR 2.54, 95% CI (1, 6.44), p<0.05 and rs1478605, OR 4.20, 95% CI (1.41, 12.49), p<0.01) even after controlling for these variables. The results suggest that genetic variations in the TSP1 gene are associated with variations in estimated pulmonary artery pressure in patients with SCA. Both rs1478604 and rs1478605 are localized to the 5' untranslated region. Bioinformatic analysis of these SNPs for putative transcription factor binding sites demonstrated that the two SNPs are associated with both gain and loss of transcription factor binding compared to the wild type. Therefore, both SNPs are potentially functional in TSP1 regulation. These data also suggest possible translational implications in light of earlier pre-clinical reports that showed that mice lacking TSP1 were protected from hypoxia-mediate pulmonary and right ventricular remodeling and showed less alterations in PA pressure. In populations without SCA, these alleles have been independently linked to risk of malaria, corneal immune function, and gastric cancer. TSP1 activity has also been linked to fibrotic renal disease in a rat model and to IRI-mediated AKI in a murine model. The mechanism implicated in some of these cases involves disordered TSP1 regulation of transforming growth factor beta (TGF-beta), whose superfamily of receptors is dysregulated in the pathogenesis of pulmonary hypertension and kidney disease. Our findings support a hypothetical model of TSP1 involvement in the pathophysiology of SCA. Efforts to seek validation of the genetic findings from this study in an independent SCA cohort are currently underway. Disclosures Isenberg: RCTI, Inc.: Equity Ownership, Patents & Royalties: US Patent No. 8236313; Vasculox, Inc.: Equity Ownership, Patents & Royalties: US Patent No. 8236313.
49
Pryzhkova, Marina, Xuan Yuan, Abhai Tripathi, David Sullivan, and Elias Zambidis. "Efficient Erythroid Differentiation of a PGD-Derived Human Pluripotent Stem Cell Line Affected with Sickle Cell Hemoglobinopathy." Blood 112, no. 11 (November 16, 2008): 539. http://dx.doi.org/10.1182/blood.v112.11.539.539.
Full textAbstract:
Abstract The technology of preimplantation genetic diagnosis (PGD) screens IVF-derived cleavage-stage embryos or oocytes from parents with inherited disorders, and is routinely used to avoid births with severe genetic disorders. More than one hundred testable genetic conditions, including severe hematologic diseases such as beta thalassemia, sickle cell anemia, and Fanconi anemia can be PCR-screened from either a micro-manipulated blastomere, or a pre-fertilization ovarian polar body. Derivation of human embryonic stem cell (hESC) lines from diseased IVF blastocysts has recently been reported, and these PGD-hESC are untested yet potentially valuable tools for investigating cellular and molecular events of human embryogenesis in diseased states. For example, a great deal of interest has recently been generated in treating hematologic diseases with genetically-corrected hematopoietic stem cells (HSC) derived from patient-specific pluripotent stem cells. Generation of hematopoietic progenitors from PGD-hESC affected with genetic syndromes may thus provide novel opportunities for testing cell-based and gene therapeutic strategies. An important candidate for such cell-based therapy includes sickle cell disease (SSD) hemoglobinopathy, a classic inherited single gene disorder resulting from the substitution of glutamic acid by valine at position 6 of the beta chain of hemoglobin. Human pluripotent stem cells derived from PGD-selected blastocysts or induced pluripotency (iPS; e.g., using patient’s somatic cells), will serve as critical reagents for testing such therapeutic strategies. In these studies, we report the characterization and erythropoietic differentiation of a novel PGD-hESC line affected with SSD hemoglobinopathy. The sickle point mutation was confirmed in this PGD-hESC line with direct genomic sequencing of the beta globin locus. This hESC line possesses typical pluripotency characteristics and forms multilineage teratomas in vivo. SSD-hESC can be efficiently differentiated to the hematopoietic lineage under serum-free conditions, and gave rise to robust primitive and definitive erythropoieses. The expression of embryonic, fetal and adult globin genes in SSD PGD-hESC derived erythroid cells was confirmed by qRT-PCR, intracytoplasmic FACS, and in situ immunostaining of PGD-hESC teratoma sections. Moreover, we defined culture conditions for massive, long-term liquid culture expansion of sickle affected erythroid progenitors that remained in an undifferentiated erythroblastic phenotype for at least two months. These sickle erythroblasts were continuously maintained as a primary cell line that could be frozen and thawed without loss of viability. In vitro-expanded sickle erythroblasts expressed CD71+CD36+ and CD71+CD235a+ phenotypes, and underwent developmentally appropriate embryonic, fetal, and adult hemoglobin switching over a period of several months. Moreover, hESC-derived erythroblasts were readily infected with Plasmodium falciparum malaria parasites, thus demonstrating their potential utility in studying the effects of this important pathogen in normal and diseased erythropoiesis. These data demonstrate the utility of using patient-specific, hemoglobinopathic hESC for generating significant numbers of erythroid progenitors for molecular, developmental, gene therapeutic, pharmacologic, and microbiological studies. We are currently conducting a comparative erythropoietic differentiation study using SSD PGD-hESC vs. SSD iPS that were generated from somatic fibroblasts using defined pluripotency factors.
50
Isgro, Antonella, Javid Gaziev, Pietro Sodani, Marco Andreani, Manuela Testi, Katia Paciaroni, Cristiano Gallucci, et al. "Hematopoietic Stem Cell Transplantation in Nigerian Children with Sickle Cell Anemia." Blood 126, no. 23 (December 3, 2015): 4598. http://dx.doi.org/10.1182/blood.v126.23.4598.4598.
Full textAbstract:
Abstract Introduction: Sickle cell anemia (SCA) remains associated with high risks of morbidity and early death. Children with SCA are at high risk for ischemic stroke and transient ischemic attacks, secondary to intracranial arteriopathy involving carotid and cerebral arteries. Children with Black African variant SCA are prone to invasive infections caused by S. pneumonia, H. influenzae and Plasmodium falciparum (in malarias areas). In Africa, malaria contributes substantially to the early mortality of patients with SCA. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment for SCA. We report our experience with transplantation in a group of Nigerian children affected by SCA. Patients and Methods: This study included 36 consecutive SCA patients who underwent bone marrow transplantation from human leukocyte antigen (HLA)-identical sibling donors between 2010 and 2015 following a myeloablative-conditioning regimen. Patients received fludarabine (30 mg/m2/day) for 5 days and a conditioning regimen including targeted intravenous busulfan (14 mg/kg total dose) and cyclophosphamide (200 mg/kg total dose). Blood samples were collected in different Nigerian Hospitals and shipped to the Laboratory of the IME Foundation in Italy where were processed for DNA preparation on a fully automated system (Maxwell, Promega, Madison, WI). Low resolution HLA-A, -B, -C, -DRB1 and -DQB1 typing was performed using the polymerase chain reaction-sequence specific oligonucleotide (PCR-SSO) technique (LABType - One Lambda, Canoga Park, CA). Results: The median patient age was 10 years (range 2-17 years). Before transplantation, seventeen patients had recurrent, painful, vaso-occlusive crisis; twelve patients had recurrent painful crisis in association with acute chest syndrome; three patients experienced ischemic stroke and recurrent vaso-occlusive crisis; two patients experienced ischemic stroke; one patient exhibited leucocytosis; and one patient exhibited priapism. Of the 36 patients, 33 survived without sickle cell disease, with Lansky/Karnofsky scores of 100, following a myeloablative-conditioning regimen. The probabilities of survival, SCA-free survival, and transplant-related mortality after transplant were 92%, 92%, and 8%, respectively. All surviving patients remained free of any SCA-related events after transplantation. Within the frame of the HSCT program for the treatment of SCA, a total of 124 Nigerian families with 2 to 11 children (average 2.5) were typed for five HLA loci (A, B, C, DRB1 and DQB1) and the phased genotypes were unambiguously determined. Thirty-six percent of the patients had at his disposal within the family a HLA compatible sibling. Conclusion: The protocols used for the preparation to the transplant in thalassemia are very effective also in the other severe hemoglobinopathy as in the sickle cell anemia with more than 90% disease free survival. If a SCA patient has a HLA identical family member, the allogeneic cellular gene therapy through the transplantation of the hematopoietic stem cells should be performed as soon as possible, before the disease progresses through a treatment-related irreversible organ damage. Disclosures No relevant conflicts of interest to declare.