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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.
Cardiac Subcellular Function During Diabetes
Published in Grant N. Pierce, Robert E. Beamish, Naranjan S. Dhalla, Heart Dysfunction in Diabetes, 2019
Grant N. Pierce, Robert E. Beamish, Naranjan S. Dhalla
5′-Nucleotidase is an enzyme which is responsible for the production of adenosine, a potent vasodilatory substance.75 The depression in 5′-nucleotidase activity in sarcolemma from diabetic rat hearts is difficult to reconcile with studies which have reported no change72 or even slight increase in coronary flow rates in diabetic hearts.73,74 It may be that the role of adenosine in the coronary vasculature has become severely altered during diabetes. There is support for this contention. Downing et al.76 found adenosine enhances coronary sinus flow rates in control animals but had no effect on this flow in diabetic animals. It is important to remember that coronary flow is regulated by many compounds and factors other than adenosine77 and the picture may be quite complex. A recent study has identified a defect in sarcolemmal membrane phosphatidylethanolamine N-methylation in hearts from diabetic animals.78 The significance of this finding with respect to the function of the diabetic heart is difficult to assess because the importance of sarcolemmal methylation has not yet been established.
The Ultrastructure And Pathobiology Of Urinary Bladder Cancer
Published in George T. Bryan, Samuel M. Cohen, The Pathology of Bladder Cancer, 2017
Bendicht U. Pauli, Joseph Alroy, Ronald S Weinstein
Enzyme activities have been measured in plasma membrane fractions of calf and sheep urinary bladder epithelium.63,86 The lumenal membrane of superficial cells in calf urinary bladder has low activities of Mg2+-ATPase, (Na+ + K +)-ATPase, and 5′-nucleotidase64 (see Table 1). The plasma membrane of sheep transitional cells shows significant activities of Mg2+-ATPase and B-D-glucosidase, but relatively low activity of 5′-nucleotidase86 (see Table 2). Low 5′-nucleotidase activity is apparently a characteristic of normal transitional cells.
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.
Phenolic Constituents and Inhibitory Effects of Hibiscus sabdariffa L. (Sorrel) Calyx on Cholinergic, Monoaminergic, and Purinergic Enzyme Activities
Published in Journal of Dietary Supplements, 2018
Ganiyu Oboh, Taiwo M. Adewuni, Adedayo O. Ademiluyi, Tosin A. Olasehinde, Ayokunle O. Ademosun
Overexpression of ecto-5′ nucleotidase (E-NTDase) has been reported in some neurodegenerative conditions associated with neuroinflammation and neuroimmune reactions (Burnstock, 2008). Ecto-5′ nucleotidase plays an important role in purinergic transmission and nucleotide-mediated signaling via the regulation of the hydrolysis of adenosine monophosphate to adenosine and inorganic phosphate. Alteration in E-NTDase activity can increase levels of adenosine in the synaptic cleft, which may in turn disrupt the release of other neurotransmitters such as ACh, dopamine, glutamate, epinephrine, and noradrenaline. Our results demonstrate that sorrel extract reduced the activity of E-NTDase activity in rat brain. The ability of sorrel extract to reduce E-NTDase activity will cause adenosine to be available at the synaptic cleft at physiological levels. Adenosine is a neuromodulator and has been reported to play an important role in protecting the brain against neuronal dysfunction. The inhibitory effects displayed by the extracts could be linked to the phenolic constituents. Rutin, kaempferol, quercetin, and chlorogenic and caffeic acids have been reported to contribute to the inhibition of E-NTDase activity (Boligon et al., 2015). However, the molecular basis for the inhibition of the enzyme is not well elucidated.
Blood-flow restricted resistance training in patients with sporadic inclusion body myositis: a randomized controlled trial
Published in Scandinavian Journal of Rheumatology, 2018
AN Jørgensen, P Aagaard, U Frandsen, E Boyle, LP Diederichsen
Twenty-two biopsy-validated (31) sIBM patients were recruited for this study. The inclusion criterion was a ‘definite sIBM’ diagnosis according to Griggs’ criteria (31), and exclusion criteria were lack of gait function, co-morbidities contraindicating the use of BFR training (previous deep vein thrombosis/pulmonary embolism or known peripheral ischaemic disease), and co-morbidities preventing resistance training [severe heart/lung disease, uncontrolled hypertension (systolic blood pressure > 160 mmHg, diastolic blood pressure > 100 mmHg), severe knee/hip arthritis]. The presence of antibodies to cytosolic 5-nucleotidase (anti-cN1A) was investigated in all patients using enzyme-linked immunosorbent assay (32–34). Patients who received immunosuppressive treatment (azathiprine, methotrexate, prednisolone) were kept on fixed medication dosage for 3 months before and during the intervention phase and patients were encouraged to maintain their existing lifestyle, and continue regular physiotherapy or other types of rehabilitation training if initially engaged in such activities. Following baseline examinations, patients were allocated to either 12 weeks of BFR training or a non-exercising control group, using a random 1:1 allocation ratio design. Study outcomes were collected at baseline and at 12 weeks’ follow-up.