Rozprawy doktorskie: „Lactic acidosis in ruminants”

1

Hutton, Peter. "Antimicrobial plants of Australia have the potential to prevent lactic acidosis in ruminants". University of Western Australia. School of Animal Biology, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0159.

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[Truncated abstract] Antimicrobial growth promoters are added to feed to prevent lactic acidosis in ruminant animals by selectively inhibiting rumen bacteria that produce lactic acid. However, recently imposed or impending bans on the use of antimicrobial growth promoters in animal production have lead to a critical need to find practical alternatives that are safe for the animal and consumer and that obtain similar production benefits. I investigated bioactive plants of Australia for their potential to prevent lactic acidosis in ruminants. The unifying hypothesis tested was that plants would be identified that selectively inhibit lactic acid-producing bacteria and consequently protect against lactic acidosis. This hypothesis was tested in a three phase process: phase 1, plant selection and collection; phase 2, a three stage protocol for screening plants and essential oils; phase 3, in vivo experiments and chemical fractionation of the most promising plant. I developed an in vitro bioassay that simulated acidosis by adding glucose to rumen fluid in Bellco tubes and incubating for 5 h (Chapter 4). The pH and gas production were used as indicators of acidosis and fermentation activity. I used this bioassay to screen ninety-five plants (dried and ground material from 79 species) and ten essential oils and included a negative control (oaten chaff) and a positive control (virginiamycin). One plant, Eremophila glabra, produced a similar pH (5.63) to the positive control (5.43) although it inhibited gas production to a moderate extent (P < 0.05). ... Seven serrulatane diterpenes were identified to be the major secondary metabolites in E. glabra. The metabolites were screened using a broth dilution and microtitre spectrophotometry method and were selective against S. bovis at between 320 and 1077 [mu]g/ mL. The serrulatanes from E. glabra were probably responsible for the activity against acidosis that I observed in vitro, because they selectively inhibited lactateproducing bacteria. It is also possible that a synergy between serrulatanes and possibly other metabolites are responsible for the activity observed in vitro. The results from my experiments support the role that bioactive plants may have to replace the antibiotics that are added to livestock feed. Australian plants were identified containing compounds that were active against the bacterial processes responsible for ruminant acidosis. To my knowledge this is the first work undertaken to identify bioactive plants of Australia for their potential to prevent acidosis. I developed in vitro screening bioassays that targeted key indicators of acidosis. These bioassays enabled me to identify 5 plants from the 104 screened that could potentially control acidosis. One of these plants in particular, E. glabra, showed a level of activity in vitro that was comparable to antibiotic protection against acidosis. The exciting in vitro results were not demonstrated in vivo but only one dose level of E. glabra was used, which was based on the in vitro work. In contrast to the in vitro system the rumen is a continuous flow system with greater complexity and it is possible that the concentration of E. glabra that I used in vivo was not optimum. This places importance on future dose response experiments to confirm the efficacy of E. glabra in vivo.

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Wiryawan, I. Komang Gede. "Microbial control of lactic acidosis in grain-fed sheep". Title page, contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phw799.pdf.

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Bibliography: leaves 122-138. Investigates the use of microbial inoculants to prevent the onset of acidosis in acutely grain fed animals; and, the most effective combination of virginiamycin and lactic acid utilising bacteria (selenomonas ruminantium subsp. lactilytica and Megasphaera elsdenii) in controlling lactic acid accumulations in vitro.

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Nordin, Angelica. "Genetic and functional studies of hereditary myopathy with lactic acidosis". Doctoral thesis, Umeå universitet, Medicinsk och klinisk genetik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-50592.

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Hereditary myopathy with lactic acidosis (HML, OMIM#255125) is an autosomal recessive disorder which originates from Västerbotten and Ångermanland in the Northern part of Sweden. HML is characterized by severe exercise intolerance which manifests with tachycardia, dyspnea, muscle pain, cramps, elevated lactate and pyruvate levels, weakness and myoglobinuria. The symptoms arise from malfunction of the energy metabolism in skeletal muscles with defects in several important enzymes involved in the TCA cycle and the electron transport chain. All affected proteins contain iron-sulfur (Fe-S) clusters, which led to the suggestion that the disease was caused by malfunctions in either the transportation, assembly or processing of Fe-S clusters. The aim of my thesis was to identify the disease causing gene of HML and to investigate the underlying disease-mechanisms. In paper I we identified a disease-critical region on chromosome 12; a region containing 16 genes. One of the genes coded for the Fe-S cluster assembly protein ISCU and an intronic base pair substitution (g.7044G>C) was identified in the last intron of this gene. The mutation gave rise to the insertion of intron sequence into the mRNA, leading to a protein containing 15 abberant amino acids and a premature stop. In paper II we investigated why a mutation in an evolutionary well conserved protein with a very important cellular role, which in addition is expressed in almost all tissues, gives rise to a muscle-restricted phenotype. Semi-quantitative RT-PCR analysis showed that the mutant transcript constituted almost 80% of total ISCU mRNA in muscle, while in both heart and liver the normal splice form was dominant. We could also show that, in mice, complete absence of Iscu protein was coupled with early embryonic death, further emphasizing the importance of the protein in all tissues. These data strongly suggested that tissue-specific splicing was the main mechanism responsible for the muscle-specific phenotype of HML. In paper III the splicing mechanisms that give rise to the mutant ISCU transcript was further investigated. We identified three proteins; PTBP1, IGF2BP1 and RBM39, that could bind to the region containing the mutation and could affect the splicing pattern of ISCU in an in vitro system. PTBP1 repressed the inclusion of the intronic sequence, while IGF2BP1 and RBM39 repressed the total ISCU mRNA level though the effect was more pronounced for the normal transcript. Moreover, IGF2BP1 and RBM39 were also able to reverse the effect of PTBP1. IGF2BP1, though not a splicing factor, had higher affinity for the mutant sequence. This suggested that the mutation enables IGF2BP1 binding, thereby preventing the PTBP1 induced repression seen in the normal case. In conclusion, we have determined the genetic cause of HML, identifying a base pair substitution in the last intron of the ISCU gene that gives rise to abnormally spliced transcript. The muscle-specific phenotype was also analyzed and tissue-specific splicing was identified as the main disease-mechanism. Furthermore, nuclear factors with ability to affect the splicing pattern of the mutant ISCU gene were identified. This work has thoroughly investigated the fundamental disease mechanisms, thus providing deeper understanding for this hereditary myopathy.

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Osler, Meg. "Associations of severe hyperlactataemia and lactic acidosis in HIV-infected patients receiving antiretroviral theraphy". Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/7438.

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Includes bibliographical references (leaves 67-70).
Severe symptomatic hyperlactataemia and lactic acidosis (SHLA) are life-threatening events that are occurring at increasing incidence levels in South Africa. Globally, the rise in SHLA cases is closely correlated to the increased accessibility of anti retroviral (ARV) medication for human immunodeficiency virus (HIV). Although hyperlactataemia and lactic acidosis were once thought of as rare conditions, they are now being recognized as important concerns when administering antiretroviral therapy. A better understanding of the risk factors for SHLA is important in combating the morbidity and mortality associated with such an adverse event.

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Nlooto, Manimbulu. "Effect of stavudine dosage reduction on the incidence of symptomatic hyperlactataemia/lactic acidosis in adults female HIV/AIDS infected patients treated at Dr George Mukhari Hospital". Thesis, University of Limpopo (Medunsa Campus), 2010. http://hdl.handle.net/10386/216.

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Theses (Msc.(Med.)(Pharmacy))--University of Limpopo, 2010.
With the availability of Highly Active Antiretroviral Therapy (HAART), one of the limitations of treatment safety is the occurrence of adverse events associated with antiretroviral agents. The aim of this study was to establish whether stavudine dosage reduction prevents toxicity from developing and minimizes the incidence of symptomatic hyperlactataemia/lactic acidosis (LA) in adults female HIV/AIDS infected patients. This retrospective study covered adult patients treated at the adult ARV clinic, Dr George Mukhari Hospital. The records of 88 patients aged between 27 and 59 years, initiated and treated from August 2004 to January 2006, were analyzed ( 67 females and 21 males). Twenty nine females started their treatment on a regimen containing 40 mg stavudine while 38 females were started on 30 mg stavudine. A group of male patients (n=21) were included for comparison. Seven males started on 40 mg stavudine and 14 were on 30 mg stavudine. Ten out of twenty nine females who started treatment on 40 mg stavudine developed elevated lactate levels while nineteen received 30 mg stavudine as reduced dose. Eight out of nineteen further developed elevated lactate levels when on 30 mg stavudine but eleven out of nineteen remained stable on treatment with 30 mg stavudine as reduced dose. In the group started on 30 mg stavudine, thirteen females out of thirty seven developed elevated lactate levels while twenty four were stable on their treatment. Key words: stavudine, dosage reduction, lactate levels, hyperlactataemia, lactic acidosis.

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Maruta, Celso Akio. "Comparação da susceptibilidade de bovinos das raças Jersey e Gir à acidose láctica ruminal, induzida experimentalmente com sacarose". Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/10/10136/tde-24072007-082404/.

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Foram utilizados neste experimento quatro garrotes Jersey (J) e quatro Gir (G), providos de cânula ruminal. Dois meses antes da indução da acidose láctica ruminal (ALR), os animais foram alimentados com dieta padronizada a base de feno e concentrado. A ALR foi induzida experimentalmente por meio da administração de sacarose intraruminal, correspondente ao peso metabólico corrigido, segundo técnica descrita por ORTOLANI (l995). Colheitas de sangue, suco de rúmen, urina, fezes e exames clínicos foram realizados nos seguintes momentos após a indução: zero, 14, 16, 18, 20, 22 e 24 horas. O pH e as concentrações de ácido láctico total, D e L e de seus sais foram determinados em todos os materiais biológicos colhidos. No sangue foram avaliados o hematócrito, os exames gasométricos e a concentração de creatinina; esta última substância também foi determinada na urina. Após a última colheita, todo o conteúdo ruminal foi completamente retirado para a determinaçãodo seu volume. Os bovinos de ambas as raças apresentaram marcante e idêntica acidose ruminal, não ocorrendo diferença no pH e na concentração de ácido láctico total, L e D no suco de rúmen. A acidose metabólica sistêmica foi moderada em ambas as raças, porém esta foi mais intensa nos bovinos J, confirmada pelas menores concentrações médias de bicarbonato e TCO2 (P < 0,00001) e pelo menor pH sangüíneo, (p < 0,025). Os garrotes J absorveram maiores quantidades de ácido láctico total e do isômero D; este último apresentou correlação negativa com o pH sangüíneo nesta raça (r = -O,78). Os garrotes G apresentaram maior capacidade homeostática de manutenção de pH sangüíneo no final da indução, provavelmente pela maior metabolização do lactato-L. Entretanto, os mesmos animais tiveram maior grau de desidratação, evidenciado pelas maiores porcentagens de hematócrito e de déficit de volume plasmático (p < 0,00001). Nessa raça ocorreu uma menor filtração glomerular, demonstrada pela maior concentração sérica de creatinina (p < 0,00001), menor depuração deste catabólito (p < 0,003) e menor volume urinário estimado (p < 0,05). Não ocorreram diferenças significativas no pH fecal entre as raças estudadas. Houve correlação negativa entre a concentração de lactato total fecal e o correspondente pH (r = - 0,65).
Four Jersey (J) and four Gir (G) rumen-cannulated steers were used. The steers were fed, for two months before the beginning of the rumen lactic acidosis (RLA) induction, a standard diet of hay and concentrates. The RLA was induced experimentally through the administration of sucrose into the rumen, according to the corrected metabolic weight, after ORTOLANI (1995). Blood, rumen fluid, urine, and fecal samples were collected and clinical examination carried out in the following times after the induction: zero, 14, 16, 18, 20, 22 and 24 hours. The pH, the total lactic acid and its L and D isomers were determined in all samples. The hematocrit, acid-base variables and the creatinine concentration were determined in the blood samples; creatinine was also determined in the urine samples. All the rumen content was evacuated in order to evaluate its volume at the 24th h. A intense rumen acidosis was reached; no differences in the rumen fluid pH and in the concentration of the total lactic acid and its isomers were found in both studied breeds. A moderate level of systemic metabolic acidosis was reached in both breeds, but lower overall mean of bicarbonate and TCO2 (p < 0.0001) as well as blood pH (p < 0.025) were found in the J steers. These steers absorbed higher amounts of total lactic and its D isomer than the G animals; the higher the blood D-lactate concentration, the lower the blood pH (r = - O.78) in the former breed. Better blood pH homeostasis were kept, at the end of induction, by the G steers, probably by their higher efficiency to metabolize L-lactate. However, the G steers exhibited a higher level of dehydration as seen by the greater hematocrit and plasma volume deficit (p < 0.00001). They also presented a lower glomerular filtration as evidenced by the higher creatinine serum levels (p < 0.00001), its lower urinary clearance (p < 0.003) and the lower estimated urinary volume (p < 0.05). There were no differences in the fecal pH values presented by both breeds. There was a negative correlation between the fecal total lactate concentration and the fecal pH (r = - 0.65).

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Rojas, Jesus Antonio. "Evaluation of the pH-stat modified approach for the treatment of non-respiratory (lactic) acidosis and vascular hyporeactivity caused by hemorrhagic shock in dogs". Columbus, Ohio : Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc%5fnum=osu1063035811.

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Thesis (Ph. D.)--Ohio State University, 2003.
Title from first page of PDF file. Document formatted into pages; contains xvi, 246 p.; also contains graphics. Includes abstract and vita. Advisor: William W. Muir, Dept. of Veterinary Clinical Sciences. Includes bibliographical references (p. 229-246).

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Rojas, Jesus Antonio Sr. "Evaluation of the pH-stat modified approach for the treatment of non-respiratory (lactic) acidosis and vascular hyporeactivity caused by hemorrhagic shock in dogs". The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1063035811.

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Sarti, Luís Marcelo Nave [UNESP]. "Efeito da suplementação com anticorpos policlonais e/ou monensina sódica sobre a saúde ruminal de bovinos jovens confinados". Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/95211.

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Made available in DSpace on 2014-06-11T19:27:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-06-12Bitstream added on 2014-06-13T19:15:02Z : No. of bitstreams: 1 sarti_lmn_me_botfmvz.pdf: 903641 bytes, checksum: 047f7d8f364a869975bf468d835307c3 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Universidade Estadual Paulista (UNESP)
O objetivo deste estudo foi avaliar os efeitos dos anticorpos policlonais, preparados contra as bactérias ruminais Streptococcus bovis, Fusobacterium necrophorum, Lactobacillus e endotoxina, ou monensina sódica sobre perfil metabólico sanguíneo e variações na ingestão diária de matéria seca de bovinos jovens confinados com diferentes níveis de concentrado. Foram utilizados 72 animais Brangus, machos, não castrados, desmamados com nove meses de idade, com peso vivo médio inicial de 261,04 ± 34,73 kg divididos em 24 baias (3 animais/baia), com 6 repetições (baias) em cada tratamento. Todos os animais foram submetidos à mesma dieta (ad libitum), tipo de alojamento e manejo. As dietas apenas foram diferentes no tocante aos aditivos alimentares utilizados: controle (sem aditivo), monensina sódica - MON, anticorpos policlonais – PAP ou mistura de monensina sódica com anticorpos policlonais – MIX, estes, na forma de pó. O delineamento experimental foi inteiramente casualizado em arranjo fatorial 2 x 2 com medidas repetidas no tempo, sendo os fatores: inclusão ou não de monensina sódica e inclusão ou não de anticorpos policlonais. Medidas de tempo foram tomadas de acordo com o período: adaptação, crescimento e terminação. Os dados de gasometria foram avaliados após 21 dias do início de cada período. A ingestão e a variação diária de matéria seca (IDMS e VIDMS, respectivamente) foram obtidas nos quatro primeiros dias após mudança do período de adaptação para crescimento e de crescimento para terminação. Não houve efeito (P<0,05) de aditivos para IDMS e VIDMS, apenas interação entre período e os 4 dias para as duas variáveis, com maior IDMS no dia 3 seguido de queda no dia 4 durante o período de crescimento e VIDMS nos quatro dias após mudança de dieta. Durante a terminação houve menor IDMS no dia 2 mas não foi observado VIDMS nos quatro primeiros...
The aim of this study was to evaluate the effects of polyclonal antibodies preparation (PAP) or monensin (MON) against rumen bacteria (Streptococcus bovis, Fusobacterium necrophorum, Lactobacillus and endotoxin) on blood metabolic profile and variations in daily dry matter intake (DM) of feedlot cattle fed high concentrate diets. Seventy-two 9-mo-old bullocks (261.04 ± 34.73 kg) were housed in 24 pens (3 bullocks/pen) and assigned to a completely randomized with 2 x 2 factorial arrangement with 6 replications per treatment. All animals received the same diet (ad libitum), type of accommodation and management. The diets treatments were different only about feed additives used: control (no additive), MON, PAP or MON + PAP (MIX). Factors were inclusion or not of PAP or MON, at a dose of 300 mg/kg DM or at 30 mg/ kg DM, respectively. Measures over time were taken according to the phase: adaptation, growing and finishing. Blood samples were collected and evaluated after 21 days of the beginning of each phase. The intake and daily variation of dry matter (IDMS and VIDMS, respectively) were obtained in the first four days of each phase. There was no effect (P < 0.05) additive for IDMS and VIDMS, only interaction between phase and four days for both variables, with higher IDMS on day 3 and then decreased on day 4 during the growth phase and VIDMS during four days after changing the diet. During the finishing, IDMS was lower on day 2, but was not observed VIDMS the first four days after change of diet. PAP and MON treatments had higher blood pH compared to MIX, but not different from control. In the finishing phase was observed lower blood pH compared with other phases... (Complete abstract click electronic access below)

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Rafael, Arenas-Pinto A. "Studies on clinical and epidemiological factors associated with peripheral neuropathy and severe hyperlactatemia or lactic acidosis in HIV-infected adults exposed to nucleoside analogues reverse transcriptase inhibitors". Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1444011/.

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Studies on mitochondrial dysfunction in HIV-infected adults exposed to anti-retroviral therapy. A significant proportion of HIV-infected patients who require anti-retroviral therapy are or have been exposed to nucleoside analogue reverse transcriptase inhibitors (NRTIs). It has been consistently suggested that most of the NRTI-attributed adverse drug reactions (ADR) are due to mitochondrial dysfunction. In a sub-analysis of a large randomised clinical trial (Delta) the incidence of peripheral neuropathy (PN) was constant over time in all study arms, which does not support the hypothesis of cumulative toxicity previously proposed for NRTI-induced ADR. Patients taking zidovudine (AZT)/zalcitabine (ddC) combination were more likely to develop PN than patients on AZT monotherapy (RH= 2.30 95%CI= 1.62 - 3.28). The incidence of PN among patients exposed to zidovudine/didanosine (AZT/ddl) combination was not different from that observed in patients on AZT. In a multi-centre case-control study including 110 cases of lactic acidosis (LA) or severe hyperlactataemia (HL) patients with < 200 CD4 cell/pl were more likely to develop HL/LA than patients with higher levels of CD4 cells (OR=3.44 95%CI= 1.64 - 7.22). Female patients were found to be at higher risk for HULA than men (OR= 4.75 95%CI= 1.96 - 11.53). Patients exposed to either d4T, ddl or the combination of these two were four to six times more likely to develop HL/LA than patients taking other NRTIs based combinations. Interestingly, cases of HL/LA were exposed to d4T for shorter periods of time than controls. Almost 10 % of the cases included in the study were asymptomatic at the time of diagnosis. All these symptom-free cases had blood lactate ranging between 5 and 7 mmol/l. Therefore, case definitions for HL or LA based on clinical presentation may underestimate the magnitude of the problem.

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Cunha, José Diogo de Oliveira e. silva Ribeiro da. "Acidose ruminal em caprinos". Master's thesis, Universidade Técnica de Lisboa. Faculdade de Medicina Veterinária, 2012. http://hdl.handle.net/10400.5/4833.

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Dissertação de Mestrado Integrado em Medicina Veterinária
Com este trabalho pretendeu-se fazer uma revisão acerca da acidose ruminal em caprinos, visto haver pouca bibliografia sobre o tema. Este trabalho foi baseado na revisão bibliográfica de artigos científicos e completado através da observação de casos clínicos ocorridos durante o estágio curricular. O objectivo deste estudo foi realizar uma breve revisão da anatomia e fisiologia do tracto gastrointestinal dos caprinos assim como a etiologia, fisiopatologia, tratamento e medidas de prevenção da acidose ruminal de forma a contribuir para o sucesso do seu tratamento e prevenção no futuro. Com base neste trabalho verifica-se que, apesar de se observarem algumas diferenças entre os bovinos e os caprinos no que respeita a escolha e selectividade dos alimentos, a etiologia da acidose ruminal em caprinos é semelhante à etiologia da acidose ruminal nos bovinos, ambas sendo originadas por uma alimentação excessivamente rica em carbohidratos facilmente fermentescíveis no rúmen pelos microrganismos presentes, o que leva à formação de concentrações muito elevadas de ácido láctico. Quando a velocidade de produção de ácido láctico excede a velocidade de metabolização do mesmo pelas bactérias do rúmen, o ácido láctico acumula-se dando origem à acidose. A prevenção da acidose ruminal está principalmente relacionada com o maneio alimentar dos caprinos e é baseada em vários princípios como a manutenção de níveis adequados de forragem/fibra efectiva, manutenção de níveis equilibrados de açúcares e amidos, adaptação adequada das cabras a transições alimentares, sobretudo na passagem da dieta de secagem para a dieta de produção.
ABSTRACT - With this document we did a review about ruminal acidosis in goats because there are few studies about the disease. This document was based on a bibliographic revision of scientific papers and it was completed with a few cases that were seen during the practical part of the Training period. The goal of this study was to make a review of the anatomy and physiology of gastrointestinal tract of goats, as well as the aetiology, physiopathology, treatment and prevention measures of ruminal acidosis in goats and also to give a contribution for the future success of treatment and prevention of this disease. Based on this review, we can verify that there are some differences between cattle and goats feeding but the aetiology of ruminal acidosis are the same, based on an excessive intake of extremely rich carbohydrates diet easily degradable by the rumen microorganisms leading to a high production of lactic acid. When the rate of production of lactic acid is higher than the rate of metabolization, the acid accumulates and originates acidosis. The prevention of ruminal acidosis is mainly related to the goat food management and is based on several principles such as gradual changes in diet, good forage/fiber ratio and adequate balanced quantity of sugars and starch.

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Sarti, Luís Marcelo Nave 1982. "Efeito da suplementação com anticorpos policlonais e/ou monensina sódica sobre a saúde ruminal de bovinos jovens confinados /". Botucatu : [s.n.], 2010. http://hdl.handle.net/11449/95211.

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Resumo: O objetivo deste estudo foi avaliar os efeitos dos anticorpos policlonais, preparados contra as bactérias ruminais Streptococcus bovis, Fusobacterium necrophorum, Lactobacillus e endotoxina, ou monensina sódica sobre perfil metabólico sanguíneo e variações na ingestão diária de matéria seca de bovinos jovens confinados com diferentes níveis de concentrado. Foram utilizados 72 animais Brangus, machos, não castrados, desmamados com nove meses de idade, com peso vivo médio inicial de 261,04 ± 34,73 kg divididos em 24 baias (3 animais/baia), com 6 repetições (baias) em cada tratamento. Todos os animais foram submetidos à mesma dieta (ad libitum), tipo de alojamento e manejo. As dietas apenas foram diferentes no tocante aos aditivos alimentares utilizados: controle (sem aditivo), monensina sódica - MON, anticorpos policlonais - PAP ou mistura de monensina sódica com anticorpos policlonais - MIX, estes, na forma de pó. O delineamento experimental foi inteiramente casualizado em arranjo fatorial 2 x 2 com medidas repetidas no tempo, sendo os fatores: inclusão ou não de monensina sódica e inclusão ou não de anticorpos policlonais. Medidas de tempo foram tomadas de acordo com o período: adaptação, crescimento e terminação. Os dados de gasometria foram avaliados após 21 dias do início de cada período. A ingestão e a variação diária de matéria seca (IDMS e VIDMS, respectivamente) foram obtidas nos quatro primeiros dias após mudança do período de adaptação para crescimento e de crescimento para terminação. Não houve efeito (P<0,05) de aditivos para IDMS e VIDMS, apenas interação entre período e os 4 dias para as duas variáveis, com maior IDMS no dia 3 seguido de queda no dia 4 durante o período de crescimento e VIDMS nos quatro dias após mudança de dieta. Durante a terminação houve menor IDMS no dia 2 mas não foi observado VIDMS nos quatro primeiros... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The aim of this study was to evaluate the effects of polyclonal antibodies preparation (PAP) or monensin (MON) against rumen bacteria (Streptococcus bovis, Fusobacterium necrophorum, Lactobacillus and endotoxin) on blood metabolic profile and variations in daily dry matter intake (DM) of feedlot cattle fed high concentrate diets. Seventy-two 9-mo-old bullocks (261.04 ± 34.73 kg) were housed in 24 pens (3 bullocks/pen) and assigned to a completely randomized with 2 x 2 factorial arrangement with 6 replications per treatment. All animals received the same diet (ad libitum), type of accommodation and management. The diets treatments were different only about feed additives used: control (no additive), MON, PAP or MON + PAP (MIX). Factors were inclusion or not of PAP or MON, at a dose of 300 mg/kg DM or at 30 mg/ kg DM, respectively. Measures over time were taken according to the phase: adaptation, growing and finishing. Blood samples were collected and evaluated after 21 days of the beginning of each phase. The intake and daily variation of dry matter (IDMS and VIDMS, respectively) were obtained in the first four days of each phase. There was no effect (P < 0.05) additive for IDMS and VIDMS, only interaction between phase and four days for both variables, with higher IDMS on day 3 and then decreased on day 4 during the growth phase and VIDMS during four days after changing the diet. During the finishing, IDMS was lower on day 2, but was not observed VIDMS the first four days after change of diet. PAP and MON treatments had higher blood pH compared to MIX, but not different from control. In the finishing phase was observed lower blood pH compared with other phases... (Complete abstract click electronic access below)
Orientador: Mário De Beni Arrigoni
Coorientador: Paulo Roberto Leme
Banca: Ricardo de Albuquerque
Banca: Paulo Henrique Mazza Rodrigues
Mestre

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Rodrigues, Frederico Augusto Mazzocca Lopes. "Tratamento adicional da acidose láctica ruminal aguda em bovinos por meio de infusão de solução salina hipertônica (7,2%)". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/10/10136/tde-08122009-114630/.

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A solução salina hipertônica (SSH) é reconhecida por seu efeito ressuscitador em animais com choque hipovolêmico, aumentando a passagem de fluidos de outros órgão e tecidos para a corrente circulatória. Bovinos acometidos com acidose láctica ruminal aguda (ALRA) freqüentemente apresentam quadros de variável desidratação devido à passagem de fluidos do organismo para o rúmen, além do estabelecimento de acidose sistêmica, devido à absorção de ácido láctico ruminal. Como o SSH aumenta o volume de urina excretada seria plausível o efeito desta solução na excreção de íons H+ e lactato na urina de animais com ALRA. Doze bovinos machos, mestiços e de um ano de idade foram utilizados para avaliar o efeito do tratamento adicional de SSH sobre a (ALRA). Após período de adaptação e implantação de cânula no rúmen os animais foram submetidos à indução de ALRA por meio de quantidade calculada de sacarose administrada diretamente no rúmen. Após 20 horas da indução os animais foram aleatoriamente divididos em dois grupos iguais. Um deles (SSH) foi tratado com 5 mL/kg P.V. de uma solução de SSH a 7,5 %, dentro de 15 min, e 20 mL/kg/P.V. de solução salina isotônica (SSI) no decorrer dos próximos 165 minutos. Foram ainda retirados 5 L de conteúdo ruminal e adicionado igual quantidade de água no rúmen. O outro grupo (SSI) foi medicado da mesma forma, com exceção do SSH que foi substituído por 5 mL/kg PV de SSI. Variáveis foram mensuradas no momento 0 (MO), na 20 h (M20h) e no decorrer dos tratamentos com ISS ou SSH (M30´, M60´, M120´e M180´). Ao término desses tratamentos todos os animais foram medicados com quantidades calculadas de solução de 1,3 % de bicarbonato de sódio IV. A acidose ruminal obtida pela indução foi de grau médio a moderado, a acidose sistêmica e a intensidade de desidratação de graus moderados. A adição de água no rúmen nos primeiros 30 min. uma ligeira acidemia (0,03 graus de pH) acompanhada de discreta hipercapnia, além de gerar um aumento significativo na osmolalidade sérica favorecendo a absorção de fluidos do rúmen para a corrente sanguínea, avaliada pelo aumento de osmolalidade ruminal. Essa condição melhorou temporariamente o restabelecimento do volume globular. O tratamento com SSH ainda permitiu a maior excreção urinária, acompanhada de aumento da taxa de filtração glomerular e maiores eliminações de íons H+, lactato e fósforo. Existiu uma alta relação positiva entre a excreção de fósforo e pH urinários (R2= 0,562). O tratamento com SSH não gerou quaisquer reações colaterais. Os presentes resultados indicam que é vantajoso e adequado o tratamento de quadros de ALRA com SSH, em relação ao protocolo com SSI.
Hypertonic saline solution (HSS) is known by causing a resurrection effect in animals with hypovolemic shock, through the passage of fluids from other organs and tissues to the blood stream. Cattle with acute rumen lactic acidosis (ARLA) usually present different degrees of dehydration, caused by the migration of fluids from the body toward the rumen, besides the development of systemic acidosis by the absorption of ruminal lactic acid. As the HSS increases the volume of excreted urine would be plausible to suggest that this solution could enhance the urinary excretion of H+ and lactate in cattle with ARLA. Twelve yearling, cross-bred, male cattle were used to evaluate the effect of the additional treatment with HSS on cattle with ARLA. After an adaption period, when a rumen cannula was implanted, the animals were submitted to an induction of ARLA by a calculated amount of sucrose into the rumen. Twenty hours later the cattle were randomly divided in two equal groups. The 1st group was treated with 5 mL/kg BW with 7.5 % HSS, within 15 min, and 20 mL/ kg BW of isotonic saline solution (ISS) for the next 165 min. Five litres of rumen fluid was withdraw and equal volume of water was added into the rumen. The following group was treated equally, but the HSS that was changed to the same volume of ISS. Several variables were measured at different times of the experiment. At the end of this protocol all animals were treated with calculated amounts of 1.3% sodium bicarbonate solution IV. The induction caused a medium to moderate ruminal acidosis, and a moderate degree of systemic acidosis and dehydration. The administration of water caused a sharp decrease in the rumen osmolality. The treatment with HSS caused a mild academia (0.03 degree of pH) followed by a discrete hypercapnia, besides generating a significant increase in the serum osmolality, which favours the rumen fluid absorption into the blood stream. This condition improved temporarily the recovering of globular volume. The treatment with HSS also increased the urinary volume excreted followed by the improvement of the glomerular filtration ratio and the global excretion of H+, lactate and phosphorus. A high positive relationship was found between the excretion of urinary phosphorus and urine pH (R2 = 0,562). No side effects were seen in cattle treated with HSS. The present results show that is beneficial and adequate the treatment of ARLA with HSS, as compared to the protocol with ISS.

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Andrade, Inês Mendes. "Impacto da toxémia de gestação em cabras na sobrevivência dos cabritos". Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2017. http://hdl.handle.net/10400.5/14234.

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Dissertação de Mestrado Integrado em Medicina Veterinária
De entre as principais doenças que afetam os pequenos ruminantes, a toxémia de gestação (TG) apresenta-se como a afeção metabólica mais frequente dos mesmos. Caracteriza-se por ter uma elevada mortalidade e, como tal, representa um grave problema económico nas explorações. O objetivo deste estudo foi determinar qual a taxa de sobrevivência dos cabritos, provenientes de cabras com TG, nascidos de cesariana, e compará-la com a taxa de sobrevivência dos cabritos nascidos por parto natural, sem auxílio humano, provenientes de cabras saudáveis. Outro objetivo deste trabalho foi determinar quais os parâmetros sanguíneos que estão associados a uma menor taxa de sobrevivência dos cabritos. Este estudo envolveu 8 cabras com TG (cujos cabritos nasceram de cesariana) e 9 cabras saudáveis (cujos cabritos nasceram de parto natural). Uma amostra de sangue foi recolhida da veia jugular até 15min, no máximo, após o nascimento, dos cabritos e foram determinados os seguintes parâmetros: Na+, K+, Cl-, HCO3 -, glucose, pH, excesso de base (BE), pCO2, anion gap (AG), ureia sanguínea (BUN, do inglês blood urea nitrogen), L-lactato, proteína total e hematócrito (Htc). Foi ainda registado o peso de cada cabrito. Nasceram 13 cabritos de parto natural, todos vivos ao sétimo dia, o que contrastou com os 21 cabritos nascidos de cesariana, dos quais 6 morreram, equivalendo a uma taxa de mortalidade de 28,5%. Foram encontradas diferenças estatisticamente significativas entre os valores dos 21 cabritos nascidos de cesariana e os dos 13 nascidos de parto natural nos seguintes parâmetros: peso, Na+, pH, HCO3 -, BE, BUN e L-lactato. Ocorreram também diferenças estatisticamente significativas nos 15 cabritos, nascidos de cesariana, que sobreviveram e os 6 cabritos que não sobreviveram nos valores de pH, BE, pCO2, BUN e L-lactato. Concluiu-se que a cetoacidose materna devida à TG teve um impacto negativo na taxa de sobrevivência dos cabritos, que apresentavam uma acidose metabólica e, nos casos fatais, com uma componente respiratória.
ABSTRACT - The impact of pregnancy toxemia in goats on the survival rate of newborn kids - Amongst the main diseases that affect small ruminants, pregnancy toxemia (PT) presents itself as the most frequent metabolic disease. It is characterized by a high mortality rate and therefore it represents a serious economic problem for the farms. The main goal of this study was to determine the survival rate of the offspring of goats with PT, born from a caesarean section and compare it to the survival rate of the offspring that was naturally delivered, from healthy goats. Another goal was to determine which blood parameters were associated to a lower survival rate of the kids. This study involved 8 goats with PT (whose kids were born from caesarean section) and 9 healthy goats (whose kids were delivered naturally). A blood sample was obtained from the kids’ jugular vein 15 minutes (maximal) after they were born and the following parameters were determined: Na+, K+, Cl-, HCO3 -, glucose, pH, base excess (BE), pCO2, anion gap (AG), blood urea nitrogen (BUN), L-lactate, total protein and packed cell volume (PCV). The weight of each kid was also determined and registered. There were 13 kids delivered naturally, all alive at the 7th day of life, differing from the 21 kids that were born from a caesarean section, of which 6 died, giving a final mortality rate of 28.5% in this last group. There were statistically significant differences between the weight and blood values of the 21 kids born from caesarean section and the 13 kids delivered naturally in the following parameters: Na+, pH, HCO3 -, BE, BUN and L-lactate. There were also statistically significant differences between the 15 kids born from caesarean section that survived and the ones also born from caesarean section who did not survive, in the following parameters: pH, BE, pCO2, BUN and L-lactate. In conclusion, maternal ketoacidosis due to PT had a negative impact on the survival rate of the offspring. In the most severe cases the new-born kids had both a metabolic and respiratory acidosis.
N/A

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Lettat, Abderzak. "Efficacité et mode d'action des bactéries propioniques et / ou lactiques pour prévenir l'acidose latente chez le ruminant". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00746197.

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L'acidose ruminale latente (ou acidose sub-clinique) est une préoccupation majeure pour la nutrition des ruminants à haut potentiel de production. Cet état se caractérise par une instabilité du microbiote et des fermentations ruminales qui s'orientent variablement vers le propionate et/ou le butyrate. L'une des stratégies de prévention de l'acidose latente consiste à distribuer dans l'alimentation des ruminants des probiotiques capables de rééquilibrer le microbiote et les fermentations ruminales (dans un sens favorable pour l'animal). L'analyse de la bibliographie montre toutefois que l'effet des probiotiques, et plus particulièrement des bactéries probiotiques (BP), est variable et parfois contradictoire ce qui serait probablement lié à l'instabilité du microbiote. Afin d'étudier la possibilité de prévenir l'acidose latente par les bactéries propioniques et/ou lactiques, nous avons émis l'hypothèse que leur efficacité dépend des orientations fermentaires dans le rumen. Des acidoses latentes butyrique et propionique caractérisées par des profils fermentaires et microbiens distincts ont été développées chez le mouton non productif et la vache laitière pour étudier l'effet et le mode d'action de la bactérie propionique P63 seule ou associée aux lactobacilles Lb. plantarum ou Lb. rhamnosus (P63, Lp + P63 et Lr + P63) sur le fonctionnement de l'écosystème ruminal et les performances animales. Chez le mouton en situation d'acidose propionique, les BP utilisées ont amélioré le pH ruminal via une réduction de la proportion en lactobacilles. Chez la vache laitière, la stabilisation du pH a été associée à une moindre disponibilité en hydrogène susceptible d'être transformé en protons, suite à une augmentation de la propionogenèse et/ou de la densité bactérienne, deux voies consommatrices d'hydrogène. Au cours de l'acidose latente butyrique, l'amélioration du pH n'a été observée que chez les moutons supplémentés avec Lp + P63. Cet effet semblait être dû à une diminution des acides gras volatils et de la proportion en S. bovis mais aussi à un pH initial faible (pH < 5,5) probablement optimal pour l'action des BP ; ce qui n'était pas le cas chez les vaches pour lesquelles le pH initial était compris entre 5,9 et 6,1. En revanche, l'efficacité digestive a été augmentée par l'association de P63 aux lactobacilles chez la vache laitière. L'association Lp + P63 a augmenté les activités fibrolytiques (cellulase, xylanase) et la digestibilité de la matière organique, tandis que Lr + P63 a amélioré la digestion des fibres et a diminué la production de méthane de 25%. Nous n'avons pas observé d'effet sur les performances zootechniques, ce qui serait probablement dû au dispositif expérimental en carré Latin qui n'est peut-être pas optimal pour mettre en évidence l'effet des BP. Nos résultats sont les premiers à démontrer l'efficacité des bactéries probiotiques pour sécuriser et/ou améliorer la digestion des rations et réduire la production de méthane chez le ruminant en acidose, et l'association de P63 avec les souches de Lactobacillus sont les plus efficaces. Enfin, nous avons validé notre hypothèse selon laquelle l'effet et le mode d'action des bactéries probiotiques pour prévenir l'acidose dépendent des orientations fermentaires dans le rumen.

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Junior, João Manoel da Silva. "Acidose metabólica em pacientes cirúrgicos de alto risco: importância prognóstica". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/5/5152/tde-03022016-154257/.

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Justificativa e Objetivos: Acidose é uma desordem muito frequente em pacientes cirúrgicos. Neste cenário, permanecem incertas as implicações clínicas da acidose e características de cada tipo. Portanto, é relevante tentar elucidar o papel de cada tipo de acidose no prognóstico de pacientes cirúrgicos de alto risco. Método: Trata-se de estudo multicêntrico observacional prospectivo, realizado em três diferentes hospitais. Os pacientes que necessitassem no pós-operatório de cuidados intensivos foram incluídos no estudo consecutivamente. Pacientes com baixa expectativa de vida (câncer sem perspectiva de tratamento), pacientes com insuficiência hepática (child B ou C), insuficiência renal (Clearence de creatinina < 50 mL/min ou hemodiálise prévia), diagnóstico de diabetes previamente foram excluídos. Os pacientes classificados na admissão da UTI quanto ao tipo de acidose que desenvolviam no pós-operatório imediato foram acompanhados até 30 dias e alta hospitalar. Tal classificação avaliou acidose metabólica, pela quantificação da diferença de base menor que -4 mmol/L, anion gap corrigido pela albumina (AG) e lactato aumentados, quando maiores que 12 e 2 mmo/L, respectivamente. Então, os pacientes foram classificados como acidose metabólica hiperlactatemica, aumentado e normal (hipercloremica) anion gap corrigido pela albumina. Resultados: O total de 618 pacientes foram incluídos durante dois anos. A incidência de acidose metabólica foi 59,1% na UTI, porém 148 (23,9%) apresentaram hipercloremica, 131 (21,2%) revelaram hiperlactatemia, 86 (13,9%) AG aumentado e em 253 (40,9%) não ocorreu acidose metabólica. Dentre todas as cirurgias, pacientes de cirurgia gastrointestinal foram associados a maiores porcentagens de acidose metabólica 46,2% versus 19,8% sem acidose, P < 0,05. Interessantemente, acidose com hipercloremia apresentou mais altos valores de cloro na admissão da UTI 115,0 ± 5,7 meq/L (P < 0,05) e receberam maiores quantidades de solução fisiológica 0,9% no intraoperatório 3000,0 (2000,0 - 4000,0) mL (P < 0,05). Entretanto, apesar dos pacientes não apresentarem diferenças entre escores de gravidade (SAPS 3, SOFA e ASA), idade e tempo cirúrgicos, ocorreram diferenças em relação a complicações e mortalidade no pós-operatório quando os pacientes mantinham acidose após 12 horas de pós-operatório. Pacientes com lactato e AG aumentados no pós-operatório imediato apresentaram maiores complicações, seguido dos pacientes com hipercloremia, e os sem acidose, respectivamente 68,8%; 68,6%; 65,8% e 59,3%, P = 0,03. Cardiovascular e renal disfunções foram as principais complicações e o grupo hiperlactatemia mostrou maior incidência em comparação aos outros grupos. O mesmo foi verificado em relação à mortalidade hospitalar e em 30 dias de seguimento os grupos hiperlactatemia, AG aumentado, hipercloremicos e sem acidose foram respectivamente 30,1% (HR 1,61, IC 95% 1,02 - 2,53); 24,3% (HR 1,37, IC 95% 0,76 - 2,46); 18,4% (HR 1,55, IC 95% 0,90 - 2,67) e 10,3%, Log-Rank = 0,03. Conclusão: A incidência de acidose metabólica em pacientes cirúrgicos de alto risco no pós-operatório é elevada, principalmente a do tipo hipercloremia. Pacientes cirúrgicos que desenvolvem acidose metabólica, dependendo das características, apresentam piores prognósticos em relação aos pacientes sem acidose, além disso, este estudo demonstra que diferentes etiologias de acidose metabólica estão associadas com diferentes taxas de mortalidade e morbidade no pós-operatório
Background: Acidosis is a very frequent disorder in surgical patients. In this patient set there remains uncertainty the clinic implications from acidosis and characteristics postoperatively. Therefore, it is very important to evaluate the role of each acidosis type in outcome for high-risk surgical patients. Methods: Multicenter prospective observational study was performed in three different hospitals. The patients who needed postoperative ICU were involved in the study consecutively. Patients with low life expectancy (cancer without treatment), hepatic failure, renal failure, and diabetic diagnosis were excluded. The patients were followed until 30 days and hospital discharge. On ICU admission, immediately postoperative period, the patients were classified to each type of acidosis. The classification evaluated metabolic acidosis as base excess < -4 mmol/L and high albumin-corrected anion gap (AG) and hyperlactatemia, both > 12 and > 2 mmol/L, respectively. So, the metabolic acidosis classification patients were related to hyperlactatemic, high and normal (hyperchloremic) albumin-corrected anion gap. Results: The study enrolled 618 patients during 2 years. Overall, the acidosis incidence was 59.1% on ICU admission, 148 (23.9%) hyperchloremic, 131 (21.2%) hyperlactatemia, 86 (13.9%) a high anion gap and in 253 (40.9%) there was no metabolic acidosis. The hyperchloremic group presented the highest chlorine level, 115.0 ± 5.7 meq/L (P < 0.05) and highest administration of 0.9% physiologic solution intraoperatively, 3000,0 (2000,0 - 4000,0) mL (P < 0.05). However, in spite of patients didn\'t present difference in profile demographic and score prognostic, those who remain after 12 hours with acidosis, depend on groups classification in postoperatively showed greater ICU complications, respectively, hyperlactatemia group 68.8%; high anion gap 68.6%; hyperchloremic 65.8% and no acidosis 59.3%, P = 0.03. Cardiovascular and renal dysfunctions were the main complications and hyperlactatemia group showed the highest in all of them. The same was verified in related to 30 days follow-up and hospital mortality rate respectively 30.1% (HR 1.61, IC 95% 1.02 - 2.53) hyperlactatemic; 24.3% (HR 1.55, IC 95% 0.90 - 2.67) high anion gap; 18.4% (HR 1.37, IC 95% 0.76 - 2.46) hyperchloremic and 10.3% no acidosis group, Log-Rank = 0.03. Conclusions: Metabolic acidosis in surgical patients is a very important complication postoperatively, mainly hyperchloremic. Patients who developed metabolic acidosis postoperatively depend on group classification presented worst outcomes compared to no acidosis patients; this result showed that different kinds of acidosis represented different outcomes postoperatively

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Adam, Clément. "Impact de l’acétoacétate sur la biologie des macrophages humains : analyse phénotypique et métabolique The roles of CSF s on the functional polarization of tumor‐associated macrophages". Thesis, Angers, 2019. http://www.theses.fr/2019ANGE0049.

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En cas d’inflammation ou de lésion, les macrophages doivent s’adapter et fonctionner dans un environnement hostile, par exemple acide. En effet, une production excessive et une accumulation locale d'acide lactique caractérise le processus inflammatoire et les lésions tissulaires. Actuellement, l'adaptation métabolique des monocytes et des macrophages humains à l'acidose et la nature des facteurs leur permettant d’acquérir un profil réparateur sont méconnus. Nous montrons dans cette étude que les monocytes différenciés in vitro en macrophages en présence du corps cétonique acétoacétate présentent une augmentation de la phosphorylation oxydative associée à l’acquisition d’un profil réparateur prononcé. De plus, des corps cétoniques et l'acétoacétate accélèrent la vitesse de cicatrisation dans modèle in vivo de cicatrisation. D’un point de vue mécanistique, les monocytes différenciés en acidose lactique accumulent des mitochondries dépolarisées et présentent des signes de mitophagie ainsi qu’une importante réduction de l'absorption des nutriments rendant leur survie dépendante de l’autophagie. De manière intéressante, l'acétoacétate prévient les conséquences du stress acide (maintien de l'intégrité et de la fonction mitochondriale), permettant aux cellules de survivre sans avoir recours à l'autophagie. L'acétoacétate apparaît donc comme un métabolite unique pour améliorer la tolérance des cellules et des tissus aux dommages induits par l'acidose et un facteur local favorisant la génération de macrophages présentant un profil réparateur
In case of inflammation or injury, macrophages must adapt and function in a hostile environment, such as an acidic environment. Indeed, excessive production and local accumulation of lactic acid, is a characteristic of inflammatory process and tissue damage. Currently, the metabolic adaptation of human monocytes and macrophages to acidosis and the nature of the factors that enable them to acquire a repair profile are poorly understood. In this study, we show that monocytes differentiated in vitro into macrophages in the presence of the acetoacetate, aketone body produced by the liver, show an increase in oxidative phosphorylation associated with the acquisition of a pronounced repair profile. In addition, ketone bodies and acetoacetate accelerate the rate of healing in an in vivo healing model. From a mechanistic point of view, monocytes differentiated into lactic acidosis accumulate depolarized mitochondria and show signs of mitophagy as well as a significant reduction in nutrient absorption making their survival dependent on autophagy. Interestingly, acetoacetate prevents the consequences of acid stress (maintaining integrity and mitochondrial function), allowing cells to survive without resorting to autophagy. Acetoacetate therefore appears as a unique metabolite to improve the tolerance of cells and tissues to damage induced by acidosis and a local factor promoting the generation of macrophages with a repair profile

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Agudelo, Florez Gloria Lucia. "Development of a model of metabolic acidosis in ruminants". 1988. http://catalog.hathitrust.org/api/volumes/oclc/18504742.html.

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Thesis (M.S.)--University of Wisconsin--Madison, 1988.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 72-83).

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Chen, Julia Ling-Yu. "Cellular Responses to Lactic Acidosis in Human Cancers". Diss., 2010. http://hdl.handle.net/10161/2387.

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The physiology of the tumor microenvironment is characterized by lower oxygen (hypoxia), higher lactate, extracellular acidosis and glucose starvation. We examined the global, transcriptional cellular responses to each of these microenvironmental stresses in vitro, projected them onto clinical breast cancer patients' samples in vivo, and returned to perform further in vitro experiments to investigate the potential mechanisms involved in these stress responses. The reciprocal exchange of information was critical and advanced our understanding of the potential clinical relevance of cellular responses.

Our expression array result showed that lactic acidosis induces a strong response, distinct from that of hypoxia in human mammalian epithelial cells (HMECs), indicating lactic acidosis is not only a by-product of hypoxia but has a unique role as a stimulant to cells in the tumor microenvironment. Cellular responses to lactosis and acidosis further demonstrated that acidosis was the main driving force in the lactic acidosis response. These responding gene signatures were then statistically projected into clinical breast cancer patients' expression data sets. The hypoxia response, as reported previously, was associated with bad prognosis, where as the lactic acidosis and acidosis responses, were associated with good prognosis. Additionally, the acidosis response could be used to separate breast tumors with high versus low aggressiveness based on its inversed correlation with metastatic character. We further discovered that lactic acidosis, in contrast to hypoxia, abolished Akt signaling. Moreover, it downregulated glycolysis and shifted energy utilization towards aerobic respiration.

We continued to examine the cellular response to lactic acidosis temporally in MCF7 cells, a breast cancer cell line. The lactic acidosis response of MCF7 cells also showed the prognostic result of better clinical outcomes in datasets of breast cancer patients. The lactic acidosis responses of HMEC and MCF cells were highly correlated. Strikingly in MCF7 cells, lactic acidosis and glucose deprivation actually induced similar transcriptional profiles, with only a few genes being oppositely regulated. Furthermore, lactic acidosis, similar to glucose starvation, induced AMPK signaling and abolished mTOR. However, lactic acidosis and glucose deprivation induced opposite glucose uptake phenotypes. Lactic acidosis significantly repressed glucose uptake whereas glucose deprivation significantly induced it. Among the genes differentially regulated by these two stresses, thioredoxin-interacting protein (TXNIP) was among the most different. The negative regulatory role of TXNIP on glucose uptake has been demonstrated previously. In the cancer research field, TXNIP is recognized as a tumor suppressor gene. We observed that lactic acidosis induced TXNIP strongly and most importantly, TXNIP played a critical role in regulating glucose uptake in cells under lactic acidosis. Furthermore, MondoA, the transcription factor and glucose sensor previously reported to regulate TXNIP induction upon glucose exposure, was also responsible for regulating TXNIP under lactic acidosis. We demonstrated that TXNIP not only plays an important role in the lactic acidosis response but also has strong prognostic power to separate breast cancer patients based on survival.

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Lemos, Francisco Manuel Pires Maia Figueira de. "Renal replacement therapies for metformin induced lactic acidosis". Dissertação, 2020. https://hdl.handle.net/10216/128850.

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A metformina é um fármaco antidiabético oral utilizado como terapia de primeira linha no tratamento da diabetes mellitus tipo 2, uma doença altamente prevalente em todo o mundo. É um fármaco seguro, barato e bem tolerado e não se associa a efeitos secundários indesejáveis como ganho de peso e crises hipoglicémicas. O efeito adverso mais perigoso relacionado com a metformina é a acidose lática, uma condição rara mas potencialmente fatal com uma taxa de mortalidade até 50%. Relativamente ao tratamento desta condição, a primeira abordagem consiste em medidas de ressuscitação e suporte. Posteriormente, tratamentos extracorporais, tais como as técnicas de substituição da função renal, são consideradas muito eficientes, tendo um papel muito importante na abordagem desta entidade clínica. Contudo, estas técnicas têm diferentes modalidades e a escolha da modalidade, o seu timing e a duração nem sempre é uma tarefa fácil dado que não existem indicações irrefutáveis no que toca a este tema.
Metformin is an oral hypoglicemic drug used as first line therapy in type 2 diabetes mellitus, a very common disease worldwide. It is well tolerated, safe and inexpensive, and it is not associated with some undesired adverse effects like weight gain or hypoglicemia. The most dangerous side effect associated with metformin use is lactic acidosis, a rare but life-threatening condition with a mortality rate up to 50%. Regarding treatment of metformin-associated lactic acidosis (MALA), initial approach consists on resuscitating the patient and assuring supportive measures. Then, extracorporeal treatments, such as renal replacement therapies (RRT), are considered very effective and their use is supported. However, renal replacement therapies have diferente modalities and choosing which modality to use, as well as its timing and duration, can be a very hard task as there are no irrefutable indications about this subject.

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Lemos, Francisco Manuel Pires Maia Figueira de. "Renal replacement therapies for metformin induced lactic acidosis". Master's thesis, 2020. https://hdl.handle.net/10216/128850.

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A metformina é um fármaco antidiabético oral utilizado como terapia de primeira linha no tratamento da diabetes mellitus tipo 2, uma doença altamente prevalente em todo o mundo. É um fármaco seguro, barato e bem tolerado e não se associa a efeitos secundários indesejáveis como ganho de peso e crises hipoglicémicas. O efeito adverso mais perigoso relacionado com a metformina é a acidose lática, uma condição rara mas potencialmente fatal com uma taxa de mortalidade até 50%. Relativamente ao tratamento desta condição, a primeira abordagem consiste em medidas de ressuscitação e suporte. Posteriormente, tratamentos extracorporais, tais como as técnicas de substituição da função renal, são consideradas muito eficientes, tendo um papel muito importante na abordagem desta entidade clínica. Contudo, estas técnicas têm diferentes modalidades e a escolha da modalidade, o seu timing e a duração nem sempre é uma tarefa fácil dado que não existem indicações irrefutáveis no que toca a este tema.
Metformin is an oral hypoglicemic drug used as first line therapy in type 2 diabetes mellitus, a very common disease worldwide. It is well tolerated, safe and inexpensive, and it is not associated with some undesired adverse effects like weight gain or hypoglicemia. The most dangerous side effect associated with metformin use is lactic acidosis, a rare but life-threatening condition with a mortality rate up to 50%. Regarding treatment of metformin-associated lactic acidosis (MALA), initial approach consists on resuscitating the patient and assuring supportive measures. Then, extracorporeal treatments, such as renal replacement therapies (RRT), are considered very effective and their use is supported. However, renal replacement therapies have diferente modalities and choosing which modality to use, as well as its timing and duration, can be a very hard task as there are no irrefutable indications about this subject.

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Cooper, David James 1956. "Cardiac dysfunction and lactic acidosis during hyperdynamic and hypovolemic shock". 1995. http://web4.library.adelaide.edu.au/theses/09MD/09mdc776.pdf.

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Bibliography: p. 137-154. This thesis details a series of studies in patients, in human volunteers and in large animals. Haemodynamics and left ventricular systolic and diastolic mechanics are reported during lactic acidosis, during therapies for lactic acidosis, and during hyperdynamic and hypovolemic shock. The study has the unifying hypothesis that cardiac dysfunction is important in hyperdynamic and hypovolemic shock and is not caused by lactic acidosis.

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Frank, Adrianna Natalie. "Akutní komplikace diabetu a jeho následky". Master's thesis, 2010. http://www.nusl.cz/ntk/nusl-285541.

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The basis of this thesis is intended to inform the reader about the general complications of acute diabetes mellitus and its consequences. It focuses on the general definitions of the diseases, etiology, morbidity, mortality, pathogenesis of the disease, clinical presentation, treatment, and future developments in hopes of treating the disease. The major focus highlights the differences between diabetic ketoacidosis and hyperglycemic hyperosmolar state, as well as understanding the complications of diabetic hypoglycemia. The most critical effects of these disorders are also emphasized; cerebral edema, vascular thrombosis, and hyperchloremic metabolic acidosis.

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Pinto, Luís Rafael Barbosa. "Acute kidney injury : a trigger on metformin's induced lactic acidosis on type 2 Diabetes Mellitus patients". Dissertação, 2018. https://hdl.handle.net/10216/112342.

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Pinto, Luís Rafael Barbosa. "Acute kidney injury : a trigger on metformin's induced lactic acidosis on type 2 Diabetes Mellitus patients". Master's thesis, 2018. https://hdl.handle.net/10216/112342.

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Padayachee, Neelaveni. "Profiling the risk factors of lactic acidosis in HIV positive adult patients on antiretroviral treatment in South Africa in the public sector". Thesis, 2012. http://hdl.handle.net/10539/11553.

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M. Pharm., Faculty of Health Sciences, University of the Witwatersrand, 2011
Background: According to the 2010 edition of the UNAIDS Report on the global AIDS epidemic, an estimated 320 000 (20%) fewer people died of AIDS-related causes in South Africa in 2009 than in 2004 due to the increase in availability of anti-retroviral medicines.(2) With this positive trend, the mindset should be shifted towards reducing adverse effects of ART. The need for permanent ART treatment and the significant increase in life expectancy have led to the observation of new, frequent, and sometimes severe drug-related adverse effects.(4) One of the most challenging and potentially dangerous side-effects is hyperlactataemia (Hlac) that may evolve to lactic acidosis (LA)(5) ART–associated Hlac may be asymptomatic, or symptomatic which in the extreme case can progress to life threatening acidosis. The latter, i.e. lactic acidosis is a fairly frequent and often misdiagnosed or under diagnosed and potentially fatal side effect of ARTs. (6) Objectives: To explore the relationship between Hlac/LA and gender, weight, dosage CD4 and regimen alterations in HIV patients on ARTs and to compare the earlier regimens to the revised regimens as independent risk factors for Hlac and LA. Sample size would be based on the hypothesis that newer regimens would reduce the incidence of Hlac and LA. Methods: A Retrospective study was conducted by reviewing 3 741 patient files from August 2004 to December 2007. This study was to assess the incidence and risk factors of Hlac/LA. Hlac was defined as a venous lactate measurement of ≥2.3mmol/L and LA was ≥5mmol/L. Immunological, virological, haemotological and biochemical results were recorded for all the patients. A second phase involved a Prospective study. Patients who were on treatment for >12 months were randomly selected from the queue at the clinic between the September 2008 and December 2009. Immunological, virological, haematological and biochemical information was recorded for all patients selected. Analysis involved descriptive statistics, comparison of means, frequency analysis and multivariate analysis. Results: Two-hundred and thirty two patients were identified with elevated lactate levels in the retrospective study. The incidence was 6.2% in this population, with gastro-intestinal symptoms, peripheral neuropathy, abdominal tenderness, rash and upper respiratory tract infection being the significant symptoms. The major risk factor was a low CD4 count. The prospective study included 292 patients with 24.3% with Hlac/LA with peripheral neuropathy (p 0.209), gastrointestinal symptoms (nausea, vomiting) (p 0.148) and abdominal tenderness (p 0.214) were the most significant symptoms. In terms of the hypothesis that newer regimens would lower the incidence of elevated lactate levels by 50%, the observed incidence of 24.3% is no different from previously reported rates. This therefore shows that although regimen changes have been implemented the overall incidence of Hlac appears to be unchanged but the LA rate was found to be significantly lower than before, 6.8 cases per 1000 patient years vs ±19 cases per 1000 person years.(16) Gastro-intestinal symptoms but not peripheral iv neuropathy; with low CD4 count, weight loss and low weight on entry were the significant risk factors, which is most likely representative of advanced disease. Conclusions: Although newer regimens have been introduced, Hlac/LA still exist. Healthworkers need to be on high alert for Hlac/LA particularly if a patient enters into the ART program with a low CD4 count and a low weight

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Prosser, Debra Olive. "Mitochondrial DNA (mtDNA) mutations in patients with suspected myoclonic epilepsy and ragged red muscle fibres (MERRF), Leigh syndrome (LS), and mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS)". Diss., 2001. http://hdl.handle.net/2263/30471.

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Mitochondrial disorders are considered to be the most common cause of metabolic abnormalities in the paediatric neurology population (Zeviani et al., 1996). These authors reported that the phenotypes observed in 25-30% of the paediatric patients in their neurology clinics were due to a mitochondrial aetiology. The genetic aetiology in an equivalently affected paediatric population in South Africa is currently unknown. This study investigated the possibility that reported mutations could account for the mitochondrial phenotypes observed in the South African population. It focussed on the most frequent paediatric mitochondrial disorders namely: Leigh Syndrome (LS), mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), and myoclonic epilepsy and ragged red muscle fibres (MERRF). A clinically well characterised group of 25 patients with mitochondrial disorders was included in this study. The molecular analysis of the mitochondrial genome was initially based on a restriction fragment length polymorphism (RFLP) screening strategy for the ten most common mitochondrial DNA (mtDNA) mutations associated with the above¬mentioned three disorders. However, during the study the mutation analysis strategy was modified to a sequencing strategy as this provided more information than the RFLP approach. The modified sequencing strategy extended the study to incorporate fifteen additional mtDNA mutations, associated with other mitochondrial disorders, and individuals included in the study were thus investigated for the presence of 25 mtDNA mutations. Moreover, the modified strategy provided additional information of the regions encompassing the reported mutations. A single patient was observed to harbour the reported A3243G MELAS mutation. This mutation was noted to be heteroplasmic in the proband and two of her maternal relatives. None of the other 24 reported mutations were observed in this patient population. One novel mtDNA alteration in the tRNALeu(UUR) gene was observed in a single patient, although the pathogenicity of this mutation remains to be investigated. Novel and reported polymorph isms, some of which are associated with specific haplogroups, were also observed when comparing sequencing data against the Cambridge reference sequence. The data generated during this study contributed towards the understanding of the uniqueness of the South African population in the global context. This was apparent from the fact that only one of the reported mutations was observed in our patient population who were clinically well characterised and displayed phenotypes similar to those reported internationally. Results form this study underlined the complexity of mitochondrial disorders and argues in favour of whole mitochondrial genome sequence information to be used for diagnostic purposes. Moreover, the results confer with the hypothesis that novel mitochondrial mutations may account for the majority of mitochondrial phenotypes observed in the South African population.
Dissertation (MSc (Human Genetics))--University of Pretoria, 2007.
Genetics
unrestricted

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Keenan, Melissa Marie. "Genetic Determinants of Cancer Cell Survival in Tumor Microenvironment Stresses". Diss., 2015. http://hdl.handle.net/10161/11361.

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In order to propagate a solid tumor, cancer cells must adapt to and survive under various tumor microenvironment (TME) stresses, such as hypoxia or lactic acidosis. Additionally, cancer cells exposed to these stresses are more resistant to therapies, more likely to metastasize and often are worse for patient prognosis. While the presence of these stresses is generally negative for cancer patients, since these stresses are mostly unique to the TME, they also offer an opportunity to develop more selective therapeutics. If we achieve a better understanding of the adaptive mechanisms cancer cells employ to survive the TME stresses, then hopefully we, as a scientific community, can devise more effective cancer therapeutics specifically targeting cancer cells under stress. To systematically identify genes that modulate cancer cell survival under stresses, we performed shRNA screens under hypoxia or lactic acidosis. From these screens, we discovered that genetic depletion of acetyl-CoA carboxylase alpha (ACACA or ACC1) or ATP citrate lyase (ACLY) protected cancer cells from hypoxia-induced apoptosis. Furthermore, the loss of ACLY or ACC1 reduced the levels and activities of the oncogenic transcription factor ETV4. Silencing ETV4 also protected cells from hypoxia-induced apoptosis and led to remarkably similar transcriptional responses as with silenced ACLY or ACC1, including an anti-apoptotic program. Metabolomic analysis found that while α-ketoglutarate levels decrease under hypoxia in control cells, α-ketoglutarate was paradoxically increased under hypoxia when ACC1 or ACLY were depleted. Supplementation with α-ketoglutarate rescued the hypoxia-induced apoptosis and recapitulated the decreased expression and activity of ETV4, likely via an epigenetic mechanism. Therefore, ACC1 and ACLY regulated the levels of ETV4 under hypoxia via increased α-ketoglutarate. These results reveal that the ACC1/ACLY-α-ketoglutarate-ETV4 axis is a novel means by which metabolic states regulate transcriptional output for life vs. death decisions under hypoxia. Since many lipogenic inhibitors are under investigation as cancer therapeutics, our findings suggest that the use of these inhibitors will need to be carefully considered with respect to oncogenic drivers, tumor hypoxia, progression and dormancy. More broadly, our screen provides a framework for studying additional tumor cell stress-adaption mechanisms in the future.

Dissertation

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Vieira, João Miguel Antunes. "Acidose ruminal : prevalência e principais causas em sistemas de engorda intensiva de bovinos". Master's thesis, 2017. http://hdl.handle.net/10437/8151.

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Orientação : Sofia van Harten
A acidose ruminal é uma doença do foro digestivo bastante frequente em sistemas de engorda intensiva (feedlot) de bovinos, levando a grandes quebras na performance dos animais. Trata-se de uma excessiva acumulação de ácido no rúmen que resulta de um desequilíbrio entre a sua produção, utilização e absorção. A gravidade desta doença está relacionada com a quantidade, frequência e duração da administração de dietas ricas em grão e pobres em fibra, podendo tratar-se de acidose aguda se houver acumulação de ácido láctico ou subaguda se houver acumulação de ácidos gordos voláteis. O objetivo deste estudo foi identificar a prevalência de lesões ruminais causadas por acidose ruminal em 6 explorações de engorda intensiva e relacioná-las com as principais causas (alimentação e maneio). De maneira a atingir este objetivo foram analisados macroscopicamente em matadouro 218 rúmenes. A avaliação do maneio praticado nas várias explorações foi feita através de um inquérito e cada alimento foi analisado em laboratório para a quantificação dos teores de matéria seca, amido, proteína bruta, gordura bruta, celulose bruta, fibra neutro detergente e fibra ácido detergente. No geral, foi encontrada uma elevada prevalência desta doença (65,6%), sendo que em termos de lesões ruminais, 47,41% dos animais analisados apresentavam lesões compatíveis com a forma subaguda da doença e 17,83% com a forma aguda. Foram também encontradas diferenças significativas nos resultados das várias explorações, o que poderá ser justificado pelas discrepâncias encontradas nas avaliações de maneio e alimentação. Desta forma demonstrou-se que o problema das acidoses ruminais é uma realidade em explorações de engorda de bovinos. Identificou-se também o fato de existirem marcadas diferenças entre explorações e que estas se devem aos fatores alimentação e maneio.
Ruminal acidosis is a common gastrointestinal disease in feedlot cattle, which can lead to poor performances. It is caused by an excessive accumulation of rumen acid resulting from an imbalance between its production, use and absorption. Its severity is related to the quantity, frequency and duration of administration of rich grain, poor in fibre diets and it may occur as an acute form, with accumulation of lactic acid or a subacute form with the accumulation of volatile fatty acids. The objective of this study was to identify the prevalence of ruminal lesions caused by ruminal acidosis in 6 feedlot farms and relate them to the main causes, feeding and management. To achieve this objective 218 rumens were macroscopically evaluated in the slaughterhouse. An evaluation of the farms management was made through an inquire and feed was analysed regarding the contents of dry matter, starch, crude protein, crude fat, crude cellulose, neutral detergent fibre and acid detergent fibre. Overall, a high prevalence of this disease was found (65,6%). Of all the animals analysed, 47.41% presented lesions compatible with the subacute form of the disease and 17.83% with the acute form. Significant differences were also found in the results of the various farms, which may be justified by the discrepancies found in the management and feeding evaluations. This way, it was demonstrated that the ruminal acidosis problem in feedlot cattle is a reality. It was also identified the fact that its prevalence may vary from farm to farm and that these variations depend on the factors feeding and management.

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Cuillerier, Alexanne. "Dysfonctions mitochondriales associées à l’acidose lactique du Saguenay-Lac-Saint-Jean révélées par l’étude d’un nouveau modèle murin de la maladie". Thèse, 2016. http://hdl.handle.net/1866/15936.

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de, Melo Almeida Rafaela. "Impact de la mutation du gène LRPPRC sur la vulnérabilité induite par un stress inflammatoire et nutritionnel in vitro et sur la morphologie cérébrale ex vivo". Thèse, 2017. http://hdl.handle.net/1866/20428.

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Thompson, Legault Julie. "L'application de la métabolomique à la découverte de nouveaux biomarqueurs chez les patients atteints d'acidose lactique". Thèse, 2013. http://hdl.handle.net/1866/11247.

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L’acidose lactique du Saguenay-Lac-St-Jean, ou syndrome de Leigh de forme canadienne-française (LSFC), est une maladie mitochondriale neurodégénérative causée par des mutations du gène LRPPRC et caractérisée par des crises d’acidose menant au décès en bas âge. On ne comprend pas encore les causes exactes de ces crises, et aucun traitement n’est actuellement disponible. L’objectif de cette étude a été de comparer le profil des métabolites sanguins et urinaires chez des sujets LSFC et des témoins, avant et après un repas, par une approche métabolomique ciblée. Le projet s’inscrit dans une démarche à long terme visant l’identification de biomarqueurs prédictifs des crises, permettant d'intervenir plus rapidement afin d’éviter le décès. Les échantillons biologiques ont été prélevés chez 9 sujets atteints du LSFC et 9 témoins appariés, à jeun et 90 minutes après un repas standardisé. Les analyses incluent un bilan biochimique et hormonal, un profil des acides aminés, des acides gras, des acides organiques et des acylcarnitines. Les métabolites significativement modifiés chez les patients peuvent être classés en deux catégories : (i) le reflet d’une dysfonction mitochondriale, et plus particulièrement de l’accumulation d’équivalents réduits en amont de la chaîne respiratoire, et (ii) des indices de risque cardiométabolique, qui s’observent davantage chez les patients adultes malgré leur jeune âge. Ainsi, il serait intéressant d’inclure au traitement des stratégies visant la diminution des facteurs de risque cardiométabolique, notamment par une modification des habitudes de vie. Notre étude démontre la pertinence d’avoir recours à la métabolomique dans l’étude des désordres de la phosphorylation oxydative.
L’acidose lactique du Saguenay-Lac-St-Jean, ou syndrome de Leigh de forme canadienne-française (LSFC), est une maladie mitochondriale neurodégénérative causée par des mutations du gène LRPPRC et caractérisée par des crises d’acidose menant au décès en bas âge. On ne comprend pas encore les causes exactes de ces crises, et aucun traitement n’est actuellement disponible. L’objectif de cette étude a été de comparer le profil des métabolites sanguins et urinaires chez des sujets LSFC et des témoins, avant et après un repas, par une approche métabolomique ciblée. Le projet s’inscrit dans une démarche à long terme visant l’identification de biomarqueurs prédictifs des crises, permettant d'intervenir plus rapidement afin d’éviter le décès. Les échantillons biologiques ont été prélevés chez 9 sujets atteints du LSFC et 9 témoins appariés, à jeun et 90 minutes après un repas standardisé. Les analyses incluent un bilan biochimique et hormonal, un profil des acides aminés, des acides gras, des acides organiques et des acylcarnitines. Les métabolites significativement modifiés chez les patients peuvent être classés en deux catégories : (i) le reflet d’une dysfonction mitochondriale, et plus particulièrement de l’accumulation d’équivalents réduits en amont de la chaîne respiratoire, et (ii) des indices de risque cardiométabolique, qui s’observent davantage chez les patients adultes malgré leur jeune âge. Ainsi, il serait intéressant d’inclure au traitement des stratégies visant la diminution des facteurs de risque cardiométabolique, notamment par une modification des habitudes de vie. Notre étude démontre la pertinence d’avoir recours à la métabolomique dans l’étude des désordres de la phosphorylation oxydative.

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Rivard, Marie-Eve. "Impact de facteurs sanguins et d'agents thérapeutiques sur la survie de fibroblastes de sujets atteints de la forme canadienne-française du syndrome de Leigh (LSFC)". Thèse, 2010. http://hdl.handle.net/1866/4760.

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La forme canadienne-française du syndrome de Leigh (LSFC) est une maladie métabolique associée à une déficience en cytochrome oxydase (COX) et caractérisée par des crises d’acidose lactique, menant à une mort prématurée. Les mécanismes qui sous-tendent l’induction des crises restent inconnus et il n’existe aucune thérapie efficace pour les prévenir. Cette étude vise à caractériser l'effet de facteurs métaboliques périphériques potentiellement altérés chez les patients LSFC sur la mort de lignées cellulaires issues de ces patients et de témoins puis, à identifier des agents thérapeutiques pouvant la prévenir. Nous postulons que (i) ces facteurs métaboliques induiront une mort prématurée des cellules de patients et que (ii) les interventions susceptibles de la prévenir pallieront les conséquences de la déficience en COX, soit la diminution des taux d’adénosine triphosphate (ATP) et l’augmentation du stress oxydant, du nicotinamide adénine dinucléotide (NADH) et des lipides toxiques. Un criblage de 8 facteurs sanguins et 10 agents thérapeutiques a été réalisé. Les paramètres mesurés incluent la nécrose, l’apoptose, l’ATP et l’activité de la COX. Les fibroblastes LSFC sont plus susceptibles à la mort par nécrose (39±6%) induite par du palmitate plus lactate, un effet associé à des niveaux d’ATP diminués (53±8%). La mort cellulaire est réduite de moitié par l’ajout combiné d’agents ciblant le NADH, l’ATP et les lipides toxiques, alors que l’ajout d’antioxydants l’augmente. Ainsi, un excès de nutriments pourrait induire la mort prématurée des cellules LSFC et, pour atténuer cette mort, il serait important de combiner plusieurs interventions ciblant différents mécanismes.
Leigh syndrome French-Canadian variant (LSFC) is a metabolic disease associated with cytochrome c oxidase (COX) deficiency and characterized by episodes of lactic acidosis, referred to as “crisis”, leading to death at an early age. The mechanisms underlying a crisis and its cellular consequences remain elusive, and there is no effective therapy. The aim of this study was to characterize the effect of peripheral metabolic factors that are potentially altered in patients with LSFC on their cells death and to identify therapeutic agents able to prevent them using cell-lineage from LSFC patients and controls. The hypothesis are that (i) these metabolic factors can induce premature death in patient cells, and (ii) interventions that could rescue these cells may target potential consequences of COX deficiency, namely low adenosine triphosphate (ATP), high nicotinamide adenine dinucleotide (NADH) and toxic lipids, as well as oxidative stress. A screening of 8 blood factors and 10 therapeutic agents was conducted in fibroblasts. Parameter measured included cell death by necrosis and apoptosis, as well as ATP level and COX activity. LSFC fibroblasts were more susceptible to necrosis (39±6%) induced by high palmitate plus lactate and this was associated with a lower ATP (53±8%). Cell death decreased 2-fold with combined interventions, which presumably act on NADH, ATP, and the accumulation of toxic lipids, but increased with antioxidants. Collectively, our results emphasize the importance of nutrient overload as a factor eliciting premature cell death in LSFC cells and of combining interventions acting through various mechanisms for cell death rescue.

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