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Myositis
Published in Jason Liebowitz, Philip Seo, David Hellmann, Michael Zeide, Clinical Innovation in Rheumatology, 2023
While only small numbers of endomysial B cells are detected in muscle biopsies of patients with IBM, B cell activation and clonal expansion were unexpectedly found, implying an antigen- driven antibody production.14, 100, 101 This was supported by the presence of anticytoplasmic 5’-nucleotidase 1A autoantibodies directed against the cN1A nuclear protein involved in RNA processing.88 These antibodies are not pathogenic or IBM-specific but simply denote the autoimmune dysregulation in IBM muscles. Plasma cells, macrophages, and myeloid dendritic cells, potent antigen-presenting cells, are also seen among the endomysial infiltrates of patients with IBM, but their significance is still unknown.100
Lesch–Nyhan disease and variants
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop
Prenatal diagnosis has regularly been accomplished by assay of the enzyme in amniocytes [49–52] or chorionic villus samples, and a considerable number of affected and nonaffected fetuses has been detected. Nucleotidase activity, which is high in villus material, may lead to the breakdown of newly formed IMP and thus cause a false-positive diagnosis of an affected fetus [51] so it is important to inhibit the nucleotidase during the assay. Among normal individuals, a certain amount of RFLP has been identified and the linkage appears to be quite tight. This has permitted its use in informative families in which the mother carries identifiable alleles for prenatal diagnosis, as well as for the detection of heterozygosity [47]. In families in which the mutation is known, determination of its presence or absence is the method of choice for prenatal diagnosis.
Biochemical Methods of Studying Hepatotoxicity
Published in Robert G. Meeks, Steadman D. Harrison, Richard J. Bull, Hepatotoxicology, 2020
Prasada Rao S. Kodavanti, Harihara M. Mehendale
This enzyme is also known as 5′-ribonucleotide phosphohydrolase, 5′-ND, and EC 3.1.3.5. 5′-Nucleotidase is localized in the membranes of hepatocyte and bile ductular cells and used as an indicator to assess obstructive liver injury (Song et al., 1969). This enzyme specifically hydrolyzes 5′-nucleotides, such as adenosine 5′-monophosphate (AMP) to their nucleosides and inorganic phosphorus. Procedures for the assay of 5′-ND are based on measuring one of these end products produced by the hydrolytic action of the enzyme.
Screening models combining maternal characteristics and multiple markers for the early prediction of preeclampsia in pregnancy: a nested case–control study
Published in Journal of Obstetrics and Gynaecology, 2022
Li Chen, Yan Pi, Kai Chang, Sifu Luo, Zhuyun Peng, Ming Chen, Lili Yu
5′-Nucleotidase (5′-ribonucleotide phosphohydrolase; 5′NT), an intrinsic membrane glycoprotein that acts as an ectoenzyme in a wide variety of mammalian cells, catalyses adenosine 5′-monophosphate (AMP) to adenosine (Sunderman 1990). Serum concentrations of 5′-nucleotidase show changes in hepatobiliary disease with considerable specificity (Phelan et al. 1971). Serum concentrations of 5′-nucleotidase are reported to increase (Bacq et al. 1996) or remain unchanged (Alvi et al. 1988) in normal pregnancy. In our present study, the concentration of 5′-nucleotidase was significantly elevated in the maternal serum of PE patients at 11–13 wks of gestation. This is the first report to identify 5′-nucleotidase as an independent risk factor for PE. The elevation of 5′-nucleotidase levels is suggestive of enhanced dephosphorylation from AMP to adenosine in PE. Previous studies found that placental adenosine represents a causative factor for the induction of maternal features associated with PE (Iriyama et al. 2015). One potentially detrimental role for adenosine signalling in PE is that adenosine stimulates the increased production of fms-like tyrosine kinase 1 (George et al. 2010). Furthermore, vascular endothelial ecto-5′nucleotidase also plays a role in controlling the circulating levels of adenosine in microvascular beds (Zukowska et al. 2015). In view of these results, we considered that 5′-nucleotidase may represent a potential marker and play an important role in the pathophysiology of PE.
3,4-Dihydroxybenzaldehyde attenuates pentachlorophenol-induced cytotoxicity, DNA damage and collapse of mitochondrial membrane potential in isolated human blood cells
Published in Drug and Chemical Toxicology, 2022
Nikhil Maheshwari, Riaz Mahmood
All metabolic enzymes were assayed in hemolysates. Hexokinase, the first enzyme of glycolysis, was assayed by the method of Bergmeyer et al. (1983). In this method NADP+ is reduced to NADPH in a coupled enzymatic reaction catalyzed by hexokinase and glucose 6-phosphate dehydrogenase (G6PD). The increase in absorbance of samples at 340 nm was recorded. Pyruvate kinase activity was also determined from a coupled enzymatic method using lactate dehydrogenase. The decrease in absorbance of solution was recorded at 340 nm (Bergmeyer et al.1974). G6PD was assayed from the conversion of NADP+ to NADPH, in presence of glucose 6-phosphate, and the increase in absorbance at 340 nm was noted (Shonk and Boxer 1964). Acid phosphatase (ACP) was assayed from the hydrolysis of p-nitrophenyl phosphate to p-nitrophenol in acidic medium. This produces the yellow p-nitrophenol which absorbs at 415 nm (Mohrenweiser and Novotny 1982). Lactate dehydrogenase was assayed from the decrease in absorbance at 340 nm due to conversion of NADH to NAD+ in presence of sodium pyruvate (Khundmiri et al.2004). The activity of 5′-nucleotidase was monitored from the hydrolysis of AMP. The inorganic phosphate released reacts with ammonium molybdate to give a blue complex that absorbs at 660 nm (Heppel and Hilmore 1951). Glyoxalase-I catalyzes the first step of the glyoxal pathway and was assayed by following the change in absorbance at 240 nm due to conversion of hemithioacetal to S-lactoylglutathione upon addition of hemolysate containing enzyme (Arai et al.2014).
Meta-inhibition of ocular and gastrointestinal dysfunctions by phenolic-rich fraction of Croton zambsicus leaves in a rat model exposed to chronic mixed metals
Published in Cutaneous and Ocular Toxicology, 2021
J. K. Akintunde, O. R. Omoniyi, O. E. Folorunsho, C. A. Moses
Eco-51-nucleotidase is an enzyme that catalyses the hydrolysis of nucleoside to nucleotide53,54 which involved in the formation of extracellular adenosine from AMP and decreased ATP level25. Increased activation of eco-51-nucleotidase activity with corresponding diminution of LDH activity in rats exposed to chronic EOMABRSL intoxication for 98 days (non-withdrawal) and 70 days (withdrawal for 28 days) implicated ATP depletion and cells injury of the ocular-gastrointestinal tissues. This may be one of the supposed mechanisms of ocular-gastrointestinal damage in rats. Similarly, chronic exposure of rats to 0.5 mL EOMABRSL activated eco-51-nucleotidase with decreased LDH activities in the ocular and colon tissues. This suggests a quick hydrolysis of cellular ATP, ADP and AMP55 causing the failure of gastrointestinal functions. Post hoc analysis of the administration of 400 mg/kg C-ZAMB fraction provided protection against ocular-gastrointestinal damage by inhibiting ocular and colon eco-51-nucleotidase activities, followed by increased LDH activity56,57. Previous studies have demonstrated that administration of flavonoids especially luteolin, quercetin and naringin can cause the down-regulation of eco-51-nucleotidase and up-regulation of LDH activities during the cellular production of ATP58–60.