Journal articles on the topic 'L-alanine Spacer'
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Nuno A.G. Graça, Bogac Ercig, Leydi Carolina Velásquez Pereira, Kadri Kangro, Paul Kaijen, Gerry A.F. Nicolaes, Agnès Veyradier, et al. "Modifying ADAMTS13 to modulate binding of pathogenic autoantibodies of patients with acquired thrombotic thrombocytopenic purpura." Haematologica 105, no. 11 (November 21, 2019): 2619–30. http://dx.doi.org/10.3324/haematol.2019.226068.
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Antibodies that develop in patients with immune thrombotic thrombocytopenic purpura (iTTP) commonly target the spacer epitope R568/F592/R660/Y661/Y665 (RFRYY). In this study we present a detailed contribution of each residue in this epitope for autoantibody binding. Different panels of mutations were introduced here to create a large collection of full-length ADAMTS13 variants comprising conservative (Y←→F), semi-conservative (Y/F→L), non-conservative (Y/F→N) or alanine (Y/F/R→A) substitutions. Previously reported Gain-of-Function (GoF, KYKFF) and truncated ‘MDTCS’ variants were also included. Sera of 18 patients were screened against all variants. Conservative mutations of the aromatic residues did not reduce the binding of autoantibodies. Moderate resistance was achieved by replacing R568 and R660 by lysines or alanines. Semi-conservative mutations of aromatic residues show a moderate effectiveness in autoantibody resistance. Non-conservative asparagine or alanine mutations of aromatic residues are the most effective. In the mixtures of autoantibodies from the majority (89%) of patients screened, autoantibodies targeting the spacer RFRYY epitope have preponderance compared to other epitopes. Reductions in ADAMTS13 proteolytic activity were observed for all full-length mutant variants, in varying degrees. The greatest activity reductions were observed in the most autoantibody-resistant variants (15-35% residual activity in FRETS-VWF73). Among these, a triple-alanine mutant RARAA showed activity in a VWF multimer assay. This study shows that non-conservative and alanine modifications of residues within the exosite-3 spacer RFRYY epitope in full-length ADAMTS13 resist the binding of autoantibodies from iTTP patients, while retaining residual proteolytic activity. Our study provides a framework for the design of autoantibody-resistant ADAMTS13 variants for further therapeutic development.
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Nishiyama, Yasuhiro, Tetsuya Yoshida, Tomonori Mori, Shigeru Ishii, and Keisuke Kurita. "Asymmetric reduction with chitosan/dihydronicotinamide conjugates: influence of l-alanine spacer arms on reducing performance." Reactive and Functional Polymers 37, no. 1-3 (June 1998): 83–91. http://dx.doi.org/10.1016/s1381-5148(97)00142-9.
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Kurita, Keisuke, Seiji Iwawaki, Shigeru Ishii, and Shin-Ichiro Nishimura. "Introduction of poly(L-alanine) side chains into chitin as versatile spacer arms having a terminal free amino group and immobilization of nadh active sites." Journal of Polymer Science Part A: Polymer Chemistry 30, no. 4 (March 30, 1992): 685–88. http://dx.doi.org/10.1002/pola.1992.080300421.
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Bao, Jialing, Khalil Bdeir, Don L. Siegel, Douglas B. Cines, and X. Long Zheng. "Inhibition of ADAMTS13 Activity By Human Neutrophil Peptide 1 (HNP-1): Potential Link Between Inflammation, Onset of Thrombotic Thrombocytopenic Purpura, and Other Thrombosis." Blood 124, no. 21 (December 6, 2014): 599. http://dx.doi.org/10.1182/blood.v124.21.599.599.
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Abstract Thrombotic thrombocytopenic purpura (TTP) is a potentially fatal syndrome associated with severe deficiency of plasma ADAMTS13 activity resulting from either mutations or autoantibodies. However, patients with severe ADAMTS13 deficiency do not always develop TTP. Rather, a trigger, such as infection or inflammation, often precedes the onset of the TTP syndrome. We hypothesized that antimicrobial human neutrophil peptides 1-3 (HNPα1-3) or α-defensins, the most abundant proteins in the granules of neutrophils, which are released at site of inflammation, activate platelets, and inhibit fibrinolysis, might help to initiate TTP. This question arose because we noted that the amino acid sequences of HNPα1-3, which are nearly identical except for one residue at the N-terminus, all contain a motif (RRY) similar to exosite 3 (659RRYGEEY665) in the spacer domain of ADAMTS13 (Fig. 1) that was shown to be critical for recognition of von Willebrand factor (VWF). Here, we found that both purified and synthetic HNPα1 bind to FRETS-VWF73 and plasma-derived VWF and inhibit proteolytic cleavage of these substrates in a concentration-dependent manner. At the final concentrations of 10 micro mol/L and 150 micro mol/L, HNPα1 completely abolished the cleavage of FRETS-VWF73 (IC50=3.5 micro mol/L) (Fig. 2) and VWF (IC50=75 micro mol/L) (not shown), respectively. Such concentrations are readily attained locally after systemic infection. Deletion or alanine substitution within the RRY motif of HNPα1 completely abolished its ability to inhibit ADAMTS13 activity assessed by FRETS-VWF73 and VWF multimer analysis. This suggests that an interaction of the RRY motif in HNPα1 with the central A2 domain of VWF is required to mediate its inhibition. In support of this hypothesis, HNPα1 interacts with a human monoclonal antibody against ADAMTS13 scFv (the single chain fragment of variable region) designated 4-20, but not scFv3-1, both isolated by phage display from patients with acquired autoimmune TTP. Hydrogen-deuterium exchange mass spectrometry has shown that the binding site for scFv4-20, but not scFv3-1, contains the RRY sequence. These results suggest that HNPα1-3 released from neutrophils following infection or inflammation may inhibit residual plasma ADAMTS13 activity in vivo similar to anti-ADAMTS13 autoantibodies by interfering with its interaction with VWF, thereby triggering the onset of hereditary and acquired autoimmune TTP. Our findings suggest a potential novel link between systemic inflammation and the pathogenesis of TTP and possibility other thrombotic sequelae. Figure 2 Figure 2. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.
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Pillai, Vikram G., Jialing Bao, Jenny McDaniel, Catherine B. Zander1, Wenjing Cao, Khalil Bdeir, Douglas B. Cines, and X. Long Zheng. "Human Neutrophil Peptides (HNPs) Enhance Thrombus Formation Under Flow By Inhibiting Proteolytic Activity of Plasma ADAMTS13 Metalloprotease." Blood 126, no. 23 (December 3, 2015): 105. http://dx.doi.org/10.1182/blood.v126.23.105.105.
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Abstract Human neutrophil peptides (HNPs) or alpha (α)-defensins are a family of small antimicrobial peptides which play important roles in innate immunity against invading bacteria, fungi, and viruses. HNPs contain 29-33 amino acid residues which share a distinct pattern of disulfide bonding. HNPs can be further subdivided into myeloid (HNPs 1-4) and enteric (HD5-6) forms. HNPs-1, -2, and -3 are structurally identical except for the first amino acid residue and are predominantly expressed in human neutrophils from which they are released at sites of infection or inflammation. Previous studies have demonstrated that HNP1 promotes thrombus formation. However, the mechanisms underlying its prothrombotic effects are not fully understood. In the present study, we demonstrate that HNP-1, -2, and -3 all inhibit plasma-derived and recombinant ADAMTS13 activity in a concentration-dependent manner as determined by the cleavage of FRETS-VWF73 (Fig. 1A & 1B) and multimeric VWF under denaturing conditions. At final concentrations of ~10-15 µM, purified and synthetic HNP-1, -2, and -3 completely abolish ADAMTS13Õs ability to cleave FRETS-VWF73 (Fig. 1A & 1B). The concentrations required for complete inhibition of proteolytic cleavage of pre-denatured VWF by ADAMTS13 using the urea dialysis method is higher, likely resulting from the removal of peptides from the reaction. HNP-1 binds to ultra large VWF released from endothelial cells, soluble multimeric VWF, GST-VWF73 peptide, and ADAMTS13 as determined by cultured endoethelial cells in a microfluidic channels and by surface plasmon resonance. The affinity (the dissociation constant, KD) for HNP-1 to bind VWF, GST-VWF73, and ADAMTS13 is 8.0 micro mol/L, 1.0 micro mol/L, and 3.2 micro mol/L, respectively. Sequence analysis reveals that the amino acid residues of HNP-1, -2, and -3 all contain a RRY motif that is also found in the spacer domain (i.e. 659RRYGEEY665) of ADAMTS13. We hypothesize that competition by HNPs with ADAMTS13 for binding to VWF-A2 domain mediates their inhibition. As shown, a deletion or alanine substitution of RRY within HNP1 nearly abolishes its ability to inhibit ADAMTS13 activity determined by the cleavage of FRETS-VWF73 (in Fig. 1C) and multimeric VWF under denaturing conditions. Similarly, HNP-beta and aliphatic (with no aromatic rings directly on the nitrogen atom) HNP-1 exhibit no inhibitory activity on ADAMTS13 (Fig. 1C). To further demonstrate the inhibitory activity of HNP1 towards ADAMTS13 under more physiological conditions, a BioFlux microfluidic system is employed. Addition of purified (native) HNP-1 (6-15 micro mol/L) to D-phenylalanyl-prolyl-arginyl chloromethyl ketone (PPACK) anticoagulated whole blood dramatically augments the rate of platelet adhesion and aggregation to the fibrillar collagen-coated surface under arterial shear stress (approximately 100 dyne per square centimeter). These results indicate that HNP-1 plays a role in the inhibition of VWF proteolysis by ADAMTS13 under flow. We conclude that HNP-1, -2, and -3 released from activated neutrophils at sites of infection or inflammation could significantly augment thrombus formation by inhibiting the local or residual plasma ADAMTS13 activity, when the circulating ADAMTS13 activity is already at critically low levels as in cases of hereditary or acquired autoimmune TTP and HUS, thereby triggering the onset of thrombotic complications. (*authors contribute equally to this work). Figure 1. Figure 1. HNPs are potent inhibitors of ADAMTS13 metalloprotease. A. Purified HNPs inhibit ADAMTS13-mediated cleavage of FRETS-VWF73; B. HNP-1, -2, and -3 all inhibit the cleavage of FRETS-VWF73 by ADAMTS13; C. No inhibition of the ADAMTS13 dependent cleavage of FRETS-VWF73 by HNP1 mutants, HNP-beta, and aliphatic HNP1 compared with WT control. Disclosures No relevant conflicts of interest to declare.
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Ando, Tadashi, and Koji Tamura. "Mechanism of Chiral-Selective Aminoacylation of an RNA Minihelix Explored by QM/MM Free-Energy Simulations." Life 13, no. 3 (March 7, 2023): 722. http://dx.doi.org/10.3390/life13030722.
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Aminoacylation of a primordial RNA minihelix composed of D-ribose shows L-amino acid preference over D-amino acid without any ribozymes or enzymes. This preference in the amino acylation reaction likely plays an important role in the establishment of homochirality in L-amino acid in modern proteins. However, molecular mechanisms of the chiral selective reaction remain unsolved mainly because of difficulty in direct observation of the reaction at the molecular scale by experiments. For seeking a possible mechanism of the chiral selectivity, quantum mechanics/molecular mechanics (QM/MM) umbrella sampling molecular dynamics (MD) simulations of the aminoacylation reactions in a modeled RNA were performed to investigate differences in their free-energy profiles along the reactions for L- and D-alanine and its physicochemical origin. The reaction is initiated by approaching a 3′-oxygen of the RNA minihelix to the carbonyl carbon of an aminoacyl phosphate oligonucleotide. The QM/MM umbrella sampling MD calculations showed that the height of the free-energy barrier for L-alanine aminoacylation reaction was 17 kcal/mol, which was 9 kcal/mol lower than that for the D-alanine system. At the transition state, the distance between the negatively charged 3′-oxygen and the positively charged amino group of L-alanine was shorter than that of D-alanine, which was caused by the chirality difference of the amino acid. These results indicate that the transition state for L-alanine is more electrostatically stabilized than that for D-alanine, which would be a plausible mechanism previously unexplained for chiral selectivity in the RNA minihelix aminoacylation.
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Dorm, Bruna Carolina, Mônica Rosas Costa Iemma, Benedito Domingos Neto, Rauany Cristina Lopes Francisco, Ivana Dinić, Nenad Ignjatović, Smilja Marković, et al. "Synthesis and Biological Properties of Alanine-Grafted Hydroxyapatite Nanoparticles." Life 13, no. 1 (December 31, 2022): 116. http://dx.doi.org/10.3390/life13010116.
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Hydroxyapatite attracts great attention as hard tissues implant material for bones and teeth. Its application in reconstructive medicine depends on its biocompatibility, which is in a function of composition and surface properties. The insertion of a protein element in the composition of implants can improve the cell adhesion and the osseointegration. Having this in mind, the proposal of this work was to develop L-alanine-grafted hydroxyapatite nanoparticles and to study their biocompatibility. Two L-alanine sources and three grafting methods were used for hydroxyapatite surface functionalization. The efficiency of grafting was determined based on X-ray powder diffraction, Fourier-transform infrared spectroscopy, thermal analyses, and field-emission scanning electron microscopy. The results indicated the formation of hydroxyapatite with 8–25 wt% of organic content, depending on the grafting method. Protein adsorption, cell adhesion, and viability studies were carried out to evaluate biological properties of grafted materials. The viability of MG-63 human osteoblastic cells following 24 h incubation with the alanine-grafted hydroxyapatite samples is well preserved, being in all cases above the viability of cells incubated with hydroxyapatite. The alanine-grafted hydroxyapatite prepared in situ and by simple mixture showed higher protein adsorption and cell adhesion, respectively, indicating their potential toward use in regenerative medicine.
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Goskulwad, Santosh P., Mohammad Al Kobaisi, Duong Duc La, Rajesh S. Bhosale, Malavath Ratanlal, Sidhanath V. Bhosale, and Sheshanath V. Bhosale. "Supramolecular Chiral Helical Ribbons of Tetraphenylethylene-Appended Naphthalenediimide Controlled by Solvent and Induced by l - and d -Alanine Spacers." Chemistry - An Asian Journal 13, no. 24 (November 26, 2018): 3947–53. http://dx.doi.org/10.1002/asia.201801421.
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Garcia, Adrien D., Cornelia Meinert, Friedrich Finger, Uwe J. Meierhenrich, and Ewald Hejl. "Racemate Resolution of Alanine and Leucine on Homochiral Quartz, and Its Alteration by Strong Radiation Damage." Life 11, no. 11 (November 11, 2021): 1222. http://dx.doi.org/10.3390/life11111222.
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Homochiral proteins orchestrate biological functions throughout all domains of life, but the origin of the uniform l-stereochemistry of amino acids remains unknown. Here, we describe enantioselective adsorption experiments of racemic alanine and leucine onto homochiral d- and l-quartz as a possible mechanism for the abiotic emergence of biological homochirality. Substantial racemate resolution with enantiomeric excesses of up to 55% are demonstrated to potentially occur in interstitial pores, along grain boundaries or small fractures in local quartz-bearing environments. Our previous hypothesis on the enhanced enantioselectivity due to uranium-induced fission tracks could not be validated. Such capillary tubes in the near-surface structure of quartz have been proposed to increase the overall chromatographic separation of enantiomers, but no systematic positive correlation of accumulated radiation damage and enantioselective adsorption was observed in this study. In general, the natural l-quartz showed stronger enantioselective adsorption affinities than synthetic d-quartz without any significant trend in amino acid selectivity. Moreover, the l-enantiomer of both investigated amino acids alanine and leucine was preferably adsorbed regardless of the handedness of the enantiomorphic quartz sand. This lack of mirror symmetry breaking is probably due to the different crystal habitus of the synthetic z-bar of d-quartz and the natural mountain crystals of l-quartz used in our experiments.
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Eder, Piotr, Agnieszka Permoda-Osip, Przemyslaw Majewski, Krzysztof Linke, and Janusz K. Rybakowski. "Agomelatine-induced liver injury in a patient with choledocholithiasis." Acta Neuropsychiatrica 27, no. 1 (October 22, 2014): 56–59. http://dx.doi.org/10.1017/neu.2014.28.
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ObjectiveA case of agomelatine-induced hepatotoxicity is described in a 47-year female patient who has received the drug, 25 mg/day, for 4 months, for the treatment of depression.MethodsThe patient was admitted to the Department of Gastroenterology because of fatigue and nausea, with concomitant elevation of alanine aminotransferase (ALT), 550 U/L, and asparagine aminotransferase (AST), 300 U/L.ResultsLiver biopsy showed diffuse lymphocyte infiltration in the dilated portal spaces without lesion of hepatic lobules. Several weeks after stopping agomelatine, the liver enzymes returned to normal. Subsequently, small gallstones in common bile duct were detected and removed by the endoscopic sphincterotomy.ConclusionsIt is hypothesized that choledocholithiasis could theoretically increase a risk of developing agomelatine-induced hepatotoxicity in this patient. Any pre-existing liver disease should be a contraindication for treatment with agomelatine.
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Izumi, Yudai, and Kazumichi Nakagawa. "Quantum Yields of Decomposition and Homo-Dimerization of Solid L-Alanine Induced by 7.2 eV Vacuum Ultraviolet Light Irradiation: An Estimate of the Half-Life of L-Alanine on the Surface of Space Objects." Origins of Life and Evolution of Biospheres 41, no. 4 (April 2, 2011): 385–95. http://dx.doi.org/10.1007/s11084-011-9237-2.
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Conte, E., G. Fanfani, M. Pieralice, R. Amerotti, and A. D'Addabbo. "Investigation on the asymmetrical induced yields in90Sr-90Y-beta-irradiated D- and L-alanines." Origins of Life and Evolution of the Biosphere 17, no. 1 (March 1986): 51–57. http://dx.doi.org/10.1007/bf01809812.
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Zhang, Qian, Fangying Ji, Lei Jiang, Qiushi Shen, Yuanxiang Mao, and Caocong Liu. "Glycine- and Alanine-Intercalated Layered Double Hydroxides as Highly Efficient Adsorbents for Phosphate with Kinetic Advantages." Nanomaterials 12, no. 4 (February 9, 2022): 586. http://dx.doi.org/10.3390/nano12040586.
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Phosphate is the main cause of eutrophication. Layered double hydroxides (LDH) are considered to be promising phosphate adsorbents due to their high affinity and large capacity. In this study, we partially intercalated zwitterionic glycine and alanine into Cl-LDH (corresponding to MgAl-LDH with interlayer anion Cl−) and synthesized efficient inorganic–organic nanohybrids for phosphate removal with kinetic advantages. Gly-Cl-LDH, Ala-Cl-LDH and Cl-LDH were characterized, and their phosphate adsorption performances under the influence of environment factors (e.g., solution pH, coexisting anions, contact time and phosphate concentration) were investigated. The results show that Gly-Cl-LDH and Ala-Cl-LDH had larger specific surface areas and larger interlayer spaces than Cl-LDH, and exhibited better adsorption performance at a lower pH and better adsorption selectivity against SO42−. Kinetic experiments indicated that Gly-Cl-LDH and Ala-Cl-LDH can reduce phosphate concentrations to a lower level in a shorter time. The pseudo-second-order kinetic constants of Gly-Cl-LDH and Ala-Cl-LDH were 1.27 times and 3.17 times of Cl-LDH, respectively (R2 > 0.996). The maximum adsorption capacities derived from a Langmuir model of Cl-LDH, Gly-Cl-LDH and Ala-Cl-LDH are 63.2 mg-P/L, 55.8 mg-P/L and 58.2 mg-P/L, respectively, which showed superiority over the prevailing phosphate adsorbents. This research provides highly efficient adsorbents for removing phosphate from aqueous solutions.
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Fox, Allison C., Jason D. Boettger, Eve L. Berger, and Aaron S. Burton. "The Role of the CuCl Active Complex in the Stereoselectivity of the Salt-Induced Peptide Formation Reaction: Insights from Density Functional Theory Calculations." Life 13, no. 9 (August 23, 2023): 1796. http://dx.doi.org/10.3390/life13091796.
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The salt-induced peptide formation (SIPF) reaction is a prebiotically plausible mechanism for the spontaneous polymerization of amino acids into peptides on early Earth. Experimental investigations of the SIPF reaction have found that in certain conditions, the l enantiomer is more reactive than the d enantiomer, indicating its potential role in the rise of biohomochirality. Previous work hypothesized that the distortion of the CuCl active complex toward a tetrahedral-like structure increases the central chirality on the Cu ion, which amplifies the inherent parity-violating energy differences between l- and d-amino acid enantiomers, leading to stereoselectivity. Computational evaluations of this theory have been limited to the protonated–neutral l + l forms of the CuCl active complex. Here, density functional theory methods were used to compare the energies and geometries of the homochiral (l + l and d + d) and heterochiral (l + d) CuCl–amino acid complexes for both the positive–neutral and neutral–neutral forms for alanine, valine, and proline. Significant energy differences were not observed between different chiral active complexes (i.e., d + d, l + l vs. l + d), and the distortions of active complexes between stereoselective systems and non-selective systems were not consistent, indicating that the geometry of the active complex is not the primary driver of the observed stereoselectivity of the SIPF reaction.
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Kanu, Kingsley Chukwuemeka, Solomon Nnah Ijioma, and Anthony Chukwubueze Okoboshi. "Biochemical and Histopathological Effects of Acute Exposure to Vinyl Acetate Monomer Vapour in Wistar Rats." Iranian Journal of Toxicology 12, no. 6 (November 1, 2018): 19–26. http://dx.doi.org/10.32598/ijt.12.6.559.1.
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Background: Vinyl acetate monomer is a commodity chemical widely used in the manufacturing of various products. The chemical is hazardous and exposure to it may occur in both occupational and non-occupational settings. The aim of this study was to characterize the effects of short-term exposure to Vinyl Acetate Monomer (VAM) vapour on the liver and lungs of Wistar rats. Methods: Mice weighing 25-30g were used to determine the acute lethal dose, while Wistar rats weighing 120-140g were randomly assigned to a control group and two experimental groups, which were exposed daily to VAM vapour for 2 or 4 hours. On the 5th day, rats were sacrificed, the blood was collected for biochemical analysis while liver and lungs were examined for histological alterations. Results: The acute lethal dose of VAM vapour was estimated to be 173.21 mg/kg body weight. A significant decline in total protein (6.725±0.10 g/dl; p<0.05) and increases in alanine aminotransferase (ALT; 33±1.47 u/l), aspartate aminotransferase (AST; 44±1.08 u/l), alkaline phosphatase (ALP u/l; 76.42±1.43), urea (22.89±0.93 mg/l), bilirubin (0.84±0.03 mg/dl) and creatinine (1.04±0.07 mg/dl) occurred in the experimental rats compared to the controls. Portal inflammation, fibrosis, and hepatitis were observed in the liver, while collapsed air spaces, thickened alveolar walls and haemorrhage were demonstrated in the lungs of the experimental rats. The extent of these lesions increased with rising exposure time to VAM vapour. Conclusion: This study demonstrated that VAM liquid was moderately toxic, while short-term exposure to VAM vapour was injurious to the lungs and liver of Wistar rats.
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Vysotskii, A. L., D. L. Vysotskii, T. A. Gudasheva, R. U. Ostrovskaya, and K. V. Anokhin. "Modulation of long-term memory by delayed administration of the amide of L-pyroglutamyl-D-alanine, a nootropic agent, in spaced and massed training in rats." Neuroscience and Behavioral Physiology 29, no. 2 (March 1999): 137–42. http://dx.doi.org/10.1007/bf02465317.
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Adamski, Michal, and Ariel Kaminski. "Effect of Microcystin-LR, Nodularin, Anatoxin-a, β-N-Methylamino-L-Alanine and Domoic Acid on Antioxidant Properties of Glutathione." Life 12, no. 2 (January 31, 2022): 227. http://dx.doi.org/10.3390/life12020227.
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Cyanobacteria produce a range of toxic secondary metabolites that affect many processes in human, animal and also plant cells. In recent years, some efforts have concentrated on deepening the understanding of their effect on living cells in the context of the disruption of antioxidant systems. Many results suggest that cyanotoxins interfere with glutathione (GSH) metabolism, which often leads to oxidative stress and, in many cases, cell death. Knowledge about the influence of cyanotoxins on enzymes involved in GSH synthesis or during its antioxidant action is relatively broad. However, to date, there is no information about the antioxidant properties of GSH after its direct interaction with cyanotoxins. In this paper, we investigated the effect of four cyanotoxins belonging to the groups of hepatotoxins (microcystin-LR and nodularin) or neurotoxins (anatoxin-a and β-N-methylamino-L-alanine) on the in vitro antioxidant properties of GSH. Moreover, the same study was performed for domoic acid (DA) produced by some diatoms. The obtained results showed that none of the studied compounds had an effect on GSH antioxidant potential. The results presented in this paper are, to the best of our knowledge, the first description of the kinetics of scavenging radicals by GSH reactions under the influence of these cyanotoxins and DA. This work provides new and valuable data that broadens the knowledge of the impact of cyanotoxins and DA on GSH metabolism and complements currently available information. Future studies should focus on the effects of the studied compounds on antioxidant systems in vivo.
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Akaboshi, Mitsuhiko, Kenichi Kawai, and Hirotoshi Maki. "Selective decomposition of either enantiomer of asparatic acid irradiated by60Co-γ-rays in the mixed aqueous solution with D- or L-alanine." Origins of Life and Evolution of the Biosphere 19, no. 3-5 (May 1989): 275–77. http://dx.doi.org/10.1007/bf02388846.
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Akaboshi, Mitsuhiko, Kenichi Kawai, Hirotoshi Maki, Wilhelm Ehrlich, and Yasuhiro Honda. "Selective decomposition of either enantiomer or aspartic acid irradiated with60Co-γ-rays in the mixed aqueous solution with D- or L-alanine." Origins of Life and Evolution of the Biosphere 20, no. 2 (March 1990): 111–19. http://dx.doi.org/10.1007/bf01808271.
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Fox, Stefan, Annika Gspandl, and Franziska M. Wenng. "Acceleration of amino acid racemization by isovaline: possible implications for homochirality and biosignature search." International Journal of Astrobiology 19, no. 3 (March 9, 2020): 276–82. http://dx.doi.org/10.1017/s1473550420000014.
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AbstractIn nature, abiotically formed amino acids are usually racemic. However, this is not true for the α,α-dialkyl amino acid isovaline (Iva), which has an L-enantiomeric excess in some specimens of carbonaceous meteorites. On the early Earth and Mars, such meteorites were sources of amino acids, including Iva. Therefore, a connection may exist between the possible chiral influence of non-racemic Iva and the origin of biological homochirality. On the surface of a young terrestrial planet, amino acids can be chemically altered in many ways. For example, high temperatures from geothermal heating can lead to racemization. Four billion years ago, active volcanism and volcanic islands provided suitable conditions for such reactions and perhaps even for early microbial life on Earth. In the current study, we investigated the influence of D- and L-Iva on the thermal racemization of L-alanine (L-Ala) and L-2-aminobutyric acid (L-Abu) in a simulated hot volcanic environment. The amino acids were intercalated in the clay mineral calcium montmorillonite (SAz-1). While Iva was resistant to racemization, partial racemization was observed for Ala and Abu after 8 weeks at 150°C. The experimental results – for example, accelerated racemization in the presence of Iva and different influences of the Iva enantiomers – suggest that the amino acid molecules interacted with each other, possibly in hydrogen-bonded dimers. Accelerated racemization of amino acids could have been an obstacle to the development of homochirality. Besides, it is also detrimental to the use of homochirality as a biosignature, for example, in the search for microbial life on Mars.
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Temdie, Romeo Joel Guemmogne, Marc Germain Kuum Minoue, Arnaud Doumogne Djasrane, Agathe Lambou Fotio, Pierre Jidibe, Emmanuel Le Fils Doumarsou Boumzina, and Theophile Dimo. "Influence of aqueous leafy stem extract of Cochlospermum tinctorium A. Rich. (Cochlospermaceae) on liver injury induced by subacute exposure of rats to carbon tetrachloride." American Journal of Biopharmacy and Pharmaceutical Sciences 2 (August 17, 2022): 7. http://dx.doi.org/10.25259/ajbps_8_2022.
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Objectives: Liver disease is a serious public health problem. There are many causes of liver disease and the liver is a vital organ in the body, so when it is damaged, its function can be affected. Cochlospermum tinctorium is a plant commonly used by Central African populations to relieve liver-related ailments such as jaundice and hepatitis. This study aimed to assess the hepatoprotective activity of aqueous leafy stem extract of C. tinctorium against liver injury induced by subacute exposure of rats to carbon tetrachloride (CCl4). Material and Methods: Thirty rats were distributed into six groups including control (H2O), healthy control (H2O), positive control (silymarin 25 mg/kg), extract control (aqueous leafy stem extract 50 mg/kg), and tests (aqueous leafy stem extract 50 or 25 mg/kg). Liver injury was induced by CCl4 (0.5 mL/kg) on the 4th and 11th days of the treatment. Rats were sacrificed on the 15th day, aspartate aminotransferase, alanine aminotransferase (ALT), gamma-glutamyltransferase (γ-GT) activity, and serum levels of total bilirubin, creatinine, and tissue oxidative stress markers (malondialdehyde, glutathione, catalase, and superoxide dismutase) were evaluated. Histological examinations of the liver and kidney were performed. A phytochemical study of C. tinctorium aqueous leafy stem extract was done. Results: This study showed that C. tinctorium aqueous leafy stem extract (50 or 25 mg/kg) significantly reduced (P < 0.01) ALT (94.79 ± 14.99 U/L) and γ-GT (10.08 ± 5.40 U/L) activity, and decreased the serum total bilirubin level compared to control. The aqueous leafy stem extract significantly diminished (P < 0.01) tissue MDA level (2.67 ± 0.05 µmol/mg protein), increased glutathione level (347.08 ± 10.81 nmol/mg protein), catalase (131.03 ± 6.99 µmol/ min/mg protein), and SOD activity (86.0 ±1.50 U/mg). Liver microphotography showed hepatic parenchyma with almost no leukocyte infiltration in the portal and perisinusoidal spaces, and an important reduction of cell necrosis following treatment with the aqueous leafy stem extract compared to the control. Conclusion: These results demonstrate that the hepatoprotective activity of the aqueous leafy stem extract of C. tinctorium may be due to its antioxidant and anti-inflammatory properties and may, therefore, justify the use of this plant as a candidate for complementary study to proceed with the development of medicine against liver diseases.
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Lee, Eun Jeoung, Yun Kim, Ji Eun Kim, Eileen Laurel Yoon, Sung Ryol Lee, and Dae Won Jun. "ALS-L1023 from Melissa officinalis Alleviates Liver Fibrosis in a Non-Alcoholic Fatty Liver Disease Model." Life 13, no. 1 (December 29, 2022): 100. http://dx.doi.org/10.3390/life13010100.
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ALS-L1023 is an ingredient extracted from Melissa officinalis L. (Labiatae; lemon balm), which is known as a natural medicine that suppresses angiogenesis. Herein, we aimed to determine whether ALS-L1023 could alleviate liver fibrosis in the non-alcoholic fatty liver disease (NAFLD) model. C57BL/6 wild-type male mice (age, 6 weeks old) were fed a choline-deficient high-fat diet (CDHFD) for 10 weeks to induce NAFLD. For the next 10 weeks, two groups of mice received the test drug along with CDHFD. Two doses (a low dose, 800 mg/kg/day; and a high dose, 1200 mg/kg/day) of ALS-L1023 were selected and mixed with feed for administration. Obeticholic acid (OCA; 10 mg/kg/day) was used as the positive control. Biochemical analysis revealed that the ALS-L1023 low-dose group had significantly decreased alanine transaminase and aspartate transaminase. The area of fibrosis significantly decreased due to the administration of ALS-L1023, and the anti-fibrotic effect of ALS-L1023 was greater than that of OCA. RNA sequencing revealed that the responder group had lower expression of genes related to the hedgehog-signaling pathway than the non-responder group. ALS-L1023 may exert anti-fibrotic effects in the NAFLD model, suggesting that it may provide potential benefits for the treatment of liver fibrosis.
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Jahangir, Sidrah, Peter John, Attya Bhatti, Muhammad Muaaz Aslam, Javaid Mehmood Malik, James R. Anderson, and Mandy J. Peffers. "LC-MS/MS-Based Serum Protein Profiling for Identification of Candidate Biomarkers in Pakistani Rheumatoid Arthritis Patients." Life 12, no. 3 (March 21, 2022): 464. http://dx.doi.org/10.3390/life12030464.
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Rheumatoid arthritis is an autoimmune disorder of complex disease etiology. Currently available serological diagnostic markers lack in terms of sensitivity and specificity and thus additional biomarkers are warranted for early disease diagnosis and management. We aimed to screen and compare serum proteome profiles of rheumatoid arthritis serotypes with healthy controls in the Pakistani population for identification of potential disease biomarkers. Serum samples from rheumatoid arthritis patients and healthy controls were enriched for low abundance proteins using ProteoMinerTM columns. Rheumatoid arthritis patients were assigned to one of the four serotypes based on anti-citrullinated peptide antibodies and rheumatoid factor. Serum protein profiles were analyzed via liquid chromatography-tandem mass spectrometry. The changes in the protein abundances were determined using label-free quantification software ProgenesisQITM followed by pathway analysis. Findings were validated in an independent cohort of patients and healthy controls using an enzyme-linked immunosorbent assay. A total of 213 proteins were identified. Comparative analysis of all groups (false discovery rate < 0.05, >2-fold change, and identified with ≥2 unique peptides) identified ten proteins that were differentially expressed between rheumatoid arthritis serotypes and healthy controls including pregnancy zone protein, selenoprotein P, C4b-binding protein beta chain, apolipoprotein M, N-acetylmuramoyl-L-alanine amidase, catalytic chain, oncoprotein-induced transcript 3 protein, Carboxypeptidase N subunit 2, Apolipoprotein C-I and Apolipoprotein C-III. Pathway analysis predicted inhibition of liver X receptor/retinoid X receptor activation pathway and production of nitric oxide and reactive oxygen species pathway in macrophages in all serotypes. A catalogue of potential serum biomarkers for rheumatoid arthritis were identified. These biomarkers can be further evaluated in larger cohorts from different populations for their diagnostic and prognostic potential.
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Shami, Ashwag, Nada K. Alharbi, Fatimah A. Al-Saeed, Aiman A. Alsaegh, Khalid M. Al Syaad, Ibrahim H. A. Abd El-Rahim, Yasser Sabry Mostafa, and Ahmed Ezzat Ahmed. "In Silico Subtractive Proteomics and Molecular Docking Approaches for the Identification of Novel Inhibitors against Streptococcus pneumoniae Strain D39." Life 13, no. 5 (May 4, 2023): 1128. http://dx.doi.org/10.3390/life13051128.
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Streptococcus pneumoniae is a notorious Gram-positive pathogen present asymptomatically in the nasophayrnx of humans. According to the World Health Organization (W.H.O), pneumococcus causes approximately one million deaths yearly. Antibiotic resistance in S. pneumoniae is raising considerable concern around the world. There is an immediate need to address the major issues that have arisen as a result of persistent infections caused by S. pneumoniae. In the present study, subtractive proteomics was used in which the entire proteome of the pathogen consisting of 1947 proteins is effectively decreased to a finite number of possible targets. Various kinds of bioinformatics tools and software were applied for the discovery of novel inhibitors. The CD-HIT analysis revealed 1887 non-redundant sequences from the entire proteome. These non-redundant proteins were submitted to the BLASTp against the human proteome and 1423 proteins were screened as non-homologous. Further, databases of essential genes (DEGG) and J browser identified almost 171 essential proteins. Moreover, non-homologous, essential proteins were subjected in KEGG Pathway Database which shortlisted six unique proteins. In addition, the subcellular localization of these unique proteins was checked and cytoplasmic proteins were chosen for the druggability analysis, which resulted in three proteins, namely DNA binding response regulator (SPD_1085), UDP-N-acetylmuramate—L-alanine Ligase (SPD_1349) and RNA polymerase sigma factor (SPD_0958), which can act as a promising potent drug candidate to limit the toxicity caused by S. pneumoniae. The 3D structures of these proteins were predicted by Swiss Model, utilizing the homology modeling approach. Later, molecular docking by PyRx software 0.8 version was used to screen a library of phytochemicals retrieved from PubChem and ZINC databases and already approved drugs from DrugBank database against novel druggable targets to check their binding affinity with receptor proteins. The top two molecules from each receptor protein were selected based on the binding affinity, RMSD value, and the highest conformation. Finally, the absorption, distribution, metabolism, excretion, and toxicity (ADMET) analyses were carried out by utilizing the SWISS ADME and Protox tools. This research supported the discovery of cost-effective drugs against S. pneumoniae. However, more in vivo/in vitro research should be conducted on these targets to investigate their pharmacological efficacy and their function as efficient inhibitors.
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Zamora Ramos, C., P. Turiel, N. Garvin Grande, M. Beladiez Giner, M. Alcalde Villar, and A. C. Valenciano. "AB0453 ARE WE DOING A CORRECT METHOTREXATE MONITORING?" Annals of the Rheumatic Diseases 82, Suppl 1 (May 30, 2023): 1416. http://dx.doi.org/10.1136/annrheumdis-2023-eular.2099.
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BackgroundMethotrexate (MTX) is an antimetabolite of folic acid commonly used for the treatment of Rheumatoid Arthritis (RA). Despite its recognized benefit in controlling the activity of the disease, it can cause side effects, such as hepatic and hematologic toxicity. This makes necessary to carry out periodic analytical controls.According to the recommendations of ACR1and EULAR2on the monitoring of MTX toxicity, the most appropriate frequency for analytical controls in patients starting treatment with MTX would be 4-6 weeks, and it could be spaced up to every 3 months when reaching a stable dose.We consider this study in view of the perception in our real clinical practice of a low frequency of analytical abnormalities that lead to modify the treatment with MTX in our patients with RA.ObjectivesTo evaluate the frequency of analytical abnormalities in patients with RA who start treatment with Methotrexate and to review the modifications in the treatments carried out based on these analytical abnormalities.MethodsRetrospective descriptive study on patients with RA who had started treatment with MTX (15 mg per week) between 2001 and 2021. The results of hematological parameters and liver function tests, obtained in the analytical controls carried out, were collected from the beginning of the treatment and during the following two years. These controls were carried out before starting MTX, one month later, at 3 months, and subsequently every 3-4 months; according to the recommendations of the clinical guidelines. The parameters collected were aspartate aminotransferase (AST), alanine aminotransferase (ALT), hemoglobin (Hb), neutrophils, and lymphocytes. Only patients treated with MTX in monotherapy, with or without corticosteroids, were included in the study. The frequency of the analytical abnormalities found was calculated and the therapeutic changes made were reviewed in the medical records.Results97 patients were included, of whom 67% were women and 33% men with a mean age of 55.94 (±12.9) years. Significant new-onset abnormalities in transaminases (>2-fold normal value: 68 U/L) were found in 8 patients (8.2%) during the 2-year monitoring. Of these, the MTX dose was modified in 6 patients (6.1%) and it was stopped in 2 patients (2.1%) due to ALT/AST>3-fold normal (102 U/L). After the suspension, the two patients normalized analytical values. Regarding the hematological parameters, anemia was observed (Hb <13 g/dl in men, <12 g/dl in women) in 10 patients (9.7%). However, none of them presented Hb < 10 g/dl and there was no treatment modification due to this alteration. Lymphopenia (lymphocytes < 0.9 x10^3/μL) was observed in 3 patients (3.1%) and neutropenia (neutrophils < 1.9 x10^3/μL) in 4 patients (4.1%). None of these patients required modifications in the treatment.ConclusionThe low incidence of analytical abnormalities found in our study makes us reconsider the frequency of analytical controls in monitoring MTX, not only to avoid unnecessary repeated venipuncture, but also the visits to health centers. On the other hand, we must not forget the cost of health and human resources that these procedures entail. Larger studies are required to elucidate the most optimal time interval required to monitor MTX toxicity in the management of patients with RA.References[1]Guidelines for monitoring drug therapy in rheumatoid arthritis. American College of Rheumatology ad hoc committee on clinical guidelines. Arthritis Rheum, 39 (1996), pp. 723-731.[2]K. Visseret al. Multinational evidence-based recommendations for the use of methotrexate in rheumatic disorders with a focus on rheumatoid arthritis: Integrating systematic literature research and expert opinion of a broad international panel of rheumatologists in the 3E initiative. Ann Rheum Dis, 68 (2009), pp. 1086-1093.Acknowledgements:NIL.Disclosure of InterestsNone Declared.
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Edwards, Christopher S., Philip R. Christensen, Greg L. Mehall, Saadat Anwar, Eman Al Tunaiji, Khalid Badri, Heather Bowles, et al. "The Emirates Mars Mission (EMM) Emirates Mars InfraRed Spectrometer (EMIRS) Instrument." Space Science Reviews 217, no. 7 (September 22, 2021). http://dx.doi.org/10.1007/s11214-021-00848-1.
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AbstractThe Emirates Mars Mission Emirates Mars Infrared Spectrometer (EMIRS) will provide remote measurements of the martian surface and lower atmosphere in order to better characterize the geographic and diurnal variability of key constituents (water ice, water vapor, and dust) along with temperature profiles on sub-seasonal timescales. EMIRS is a FTIR spectrometer covering the range from 6.0-100+ μm (1666-100 cm−1) with a spectral sampling as high as 5 cm−1 and a 5.4-mrad IFOV and a 32.5×32.5 mrad FOV. The EMIRS optical path includes a flat 45° pointing mirror to enable one degree of freedom and has a +/- 60° clear aperture around the nadir position which is fed to a 17.78-cm diameter Cassegrain telescope. The collected light is then fed to a flat-plate based Michelson moving mirror mounted on a dual linear voice-coil motor assembly. An array of deuterated L-alanine doped triglycine sulfate (DLaTGS) pyroelectric detectors are used to sample the interferogram every 2 or 4 seconds (depending on the spectral sampling selected). A single 0.846 μm laser diode is used in a metrology interferometer to provide interferometer positional control, sampled at 40 kHz (controlled at 5 kHz) and infrared signal sampled at 625 Hz. The EMIRS beamsplitter is a 60-mm diameter, 1-mm thick 1-arcsecond wedged chemical vapor deposited diamond with an antireflection microstructure to minimize first surface reflection. EMIRS relies on an instrumented internal v-groove blackbody target for a full-aperture radiometric calibration. The radiometric precision of a single spectrum (in 5 cm−1 mode) is <3.0×10−8 W cm−2 sr−1/cm−1 between 300 and 1350 cm−1 over instrument operational temperatures (<∼0.5 K NE$\Delta $ Δ T @ 250 K). The absolute integrated radiance error is < 2% for scene temperatures ranging from 200-340 K. The overall EMIRS envelope size is 52.9×37.5×34.6 cm and the mass is 14.72 kg including the interface adapter plate. The average operational power consumption is 22.2 W, and the standby power consumption is 18.6 W with a 5.7 W thermostatically limited, always-on operational heater. EMIRS was developed by Arizona State University and Northern Arizona University in collaboration with the Mohammed bin Rashid Space Centre with Arizona Space Technologies developing the electronics. EMIRS was integrated, tested and radiometrically calibrated at Arizona State University, Tempe, AZ.