Liver Diseases
George Feuer, Felix A. de la Iglesia in Molecular Biochemistry of Human Disease, 2020
Lipotropic factors (choline and methionine) and protein influence alcohol-induced steatosis. In growing rats, the lack of protein or lipotropic factors produces fatty liver.38 Primates, however, are less susceptible to protein and lipotrope deficiency than rodents.257 Treatment of patients suffering from alcoholic liver disease with choline is ineffective.483 The reason for this discrepancy is that primate and human liver contain very little choline oxidase activity as compared to rodent liver. Protein deficiency also affects the liver. In children, protein deficiency leads to steatosis. In volunteers, however, excess protein cannot prevent fat accumulation brought about by ethanol consumption.355 Ethanol impairs methionine conservation in circumstances of protein deficiency by increasing the activities of hepatic cystathionine synthetase and 5-methyltetrahydrofolate-homocysteine methyltransferase.178 In baboons and alcoholic patients, the alcohol-induced liver injury is associated with increased branched-chain amino acids and γ-amino-n-butyric acid. Following intestinal bypass for obesity, the absorption of dietary protein is reduced and plasma γ-amino-n-butyric acid branched-chain amino acids and essential amino acids, such as threonine, lysine and phenylalanine, are decreased, whereas nonessential amino acids such as glycine and serine are elevated.413 In alcoholics characteristically, the plasma level of γ-amino-n-butyric acid is enhanced.508
ExperimentaL Oral Medicine
Samuel Dreizen, Barnet M. Levy in Handbook of Experimental Stomatology, 2020
Trefz130 investigated the hypothesis that intracellular enzymes contribute in the transduction of tastes to electrical impulses by the taste cells. A histochemical survey was made in rhesus monkeys of the activity of 14 enzymes in taste buds associated with sweet, salt, sour, and bitter reception. All monkeys were killed by vascular perfusion of isoosmotic saline while under anesthesia. Tongues were incised posterior to the circumvallate papillae, and immediately thereafter regions containing taste buds were removed from well within areas classically assigned to each modality. Tissues were frozen in liquid nitrogen and sectioned on a cryostat; 14 different enzyme systems were analyzed histochemically in the tissue sections, as follows: for Krebs cycle activity — succinic dehydrogenase; for electron transport chain activity — choline oxidase, cytochrome oxidase, α-glycerophosphate dehydrogenase, β-hydroxybutyric dehydrogenase, and D-amino acid oxidase; for membrane-bound hydrolytic activity — nonspecific esterase; for membrane-bound pentose-phosphate shunt activity — NAD diaphorase and NADP diaphorase; for soluble pentose-phosphate shunt activity — glucose-6-phosphate dehydrogenase; for mitochondrial activity — adenosine triphosphatase; for Golgi complex activity — nucleotide diphosphatase; for active transport activity — alkaline phosphatase; for lysosomal activity — acid phosphatase.
Fluorescence in Histochemical Reactions
Victoria Vladimirovna Roshchina in Fluorescence of Living Plant Cells for Phytomedicine Preparations, 2020
An indirect fluorescent method for the determination of cholinesterase activity in the medicinal species Artemisia tridentate Nutt. (Turi et al. 2014) was applied using the artificial reagent 10-acetyl-3,7-dihydroxyphenoxazine (Amplex® Red reagent), a sensitive fluorogenic probe for hydrogen peroxide. Acetylcholinesterase converts the acetylcholine substrate to choline, which is then oxidized by choline oxidase (present in the mixture) to betaine and hydrogen peroxide. The emission is observed at 590 nm (excitation 530–560 nm). It should be noted that this fluorescent method has not yet been used in plant histochemistry.
Recent advances in electrochemical and optical sensing of the organophosphate chlorpyrifos: a review
Published in Critical Reviews in Toxicology, 2022
Athira Sradha S, Louis George, Keerthana P, Anitha Varghese
A CL sensor was developed using N-(4-Aminobutyl)-N-ethylsoluminol/Co2+/Chitosan hydrogels with MOF-Pt as catalyst. The hydrogels were able to produce long-lasting CL due to their high viscosity resulting in slow diffusion of molecules. AChE catalyzed acetylcholine chloride substrate to produce an intermediate product, choline. Choline oxidase further catalyzed this intermediate product to form betaine and H2O2. H2O2 then reacted with the hydrogel/MOF-Pt to produce a strong CL signal. In the presence of CP, due to the inhibition of AChE, the H2O2 production was significantly reduced resulting in decreased CL signal. It was observed that 60% of the signal intensity was maintained after 2 h (Lu et al. 2020).
Gold nanoparticles applications: from artificial enzyme till drug delivery
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Kazem Golchin, Jafar Golchin, Shahrooz Ghaderi, Neda Alidadiani, Sajjad Eslamkhah, Masoud Eslamkhah, Soodabeh Davaran, Abolfazl Akbarzadeh
An esterase is a hydrolase enzyme that ruptures esters into an acid and an alcohol in a chemical reaction in water. The reaction is called hydrolysis [40]. According to evidence, the first example of peptide-functionalized GNPs is hydrolytically active against carboxylate esters. The active units are constituted by His-Phe-OH terminating thiols [41,42]. A highly sensitive and selective fluorescent assay for the detection of acetylcholine (ACh) was developed based on enzyme mimics of Au/Ag NPs [43]. This mechanism involved is the following: reacting ACh with acetylcholinesterase (AChE) to form choline that is in turn oxidized by choline oxidase (ChOx) to produce betaine and H2O2, which reacts with Amplex UltraRed (AUR) in the presence of bimetallic NPs catalyst to form a fluorescent product [44].
Formulation and rheological evaluation of liposomes-loaded carbopol hydrogels based on thermal waters
Published in Drug Development and Industrial Pharmacy, 2022
Romaissaa Mokdad, Ali Aouabed, Vincent Ball, Feriel Fatima Si Youcef, Noureddine Nasrallah, Béatrice Heurtault, Abdelkader HadjSadok
The PC content of the formulated liposomes was determined using an enzymatic assay with the LabAssay™ Phospholipid kit (Sobioda Laboratories, Montbonnot-Saint-Martin, France) as previously described [43]. Briefly, 1–2 μL of liposomes were incubated with 200 μL of the enzymatic reagent in triplicates in a 96-well plate. The reagent contains phospholipase C that releases the choline headgroup of PC, which is then oxidized by the choline oxidase. The reaction produces hydrogen peroxide needed by the peroxidase to convert a chromogen into a blue product. After 10 min at 37 °C, the absorbance was measured at 595 nm using a microplate reader (Safas SP2000, Xenius 5801, Monaco). The PC content of each sample was determined from a calibration curve prepared with purified choline chloride. The total amount of lipids in liposome suspensions was then calculated from PC concentration by assuming that lipid composition was unchanged during the different liposome preparation steps.
Related Knowledge Centers
- Catalysis
- Chemical Reaction
- Choline
- Enzyme
- Hydrogen Peroxide
- Oxygen
- Substrate
- Product
- Glycine Betaine Aldehyde
- Oxidoreductase