Disease relevance of citric acid

• Thus, in contrast to earlier reports, aspartate and glutamate have no effect on either functional recovery from ischemia or on metabolic pathways feeding the citric acid cycle [1].
• The most frequently observed abnormalities were phenylalanine metabolites in cases of phenylketonuria (about 1%), increased excretion of benzoic acid (about 1%), and increased excretion of 2-oxoglutaric acid with or without raised urinary citric-acid levels (about 1%) [2].
• Mitochondrial dysfunction during hypoxia/reoxygenation and its correction by anaerobic metabolism of citric acid cycle intermediates [3].
• Fatty acid oxidation, substrate shuttles, and activity of the citric acid cycle in hepatocellular carcinomas of varying differentiation [4].
• When cells were treated with a solution of citric acid and magnesium sulfate prior to their staining with acridine orange, the mean rCV of cell populations of acute lymphoblastic leukemia increased while that of acute nonlymphoblastic leukemia decreased compared to their respective pretreatment values [5].

Psychiatry related information on citric acid

• Progressive alteration of the mitochondria, which occurs during chronic alcohol consumption, decreases fatty acid oxidation by interfering with citric acid cycle activity [6].
• Clinical evaluation of a citric acid inhaler for smoking cessation [7].
• These results suggest that the citric acid aerosol may promote successful smoking reduction or cessation in a subgroup of smokers and relieves withdrawal symptoms such as craving for cigarettes, a symptom difficult to treat with currently available nicotine replacement techniques [7].
• Additionally, the use of citric acid without the addition of supplemental Fe2+ in soil slurries, where the citric acid apparently extracted native metals from the soil, appeared to be somewhat effective at enhancing persulfate oxidation of TCE over extended reaction times [8].
• The results showed that although citric acid at pH 3.0-5.0 was not aversive, at pH 1.4 or 2.0 citric acid was avoided by all animals, as indicated by both consummatory behavior and licking activity [9].

High impact information on citric acid

• In these organelles the enzymes may be important in the transfer of acyl groups, which are produced by the peroxisomal beta-oxidation enzymes, to the mitochondria for oxidation in the citric acid cycle [10].
• The mutant mice have decreased CO2 production but increased ketone body synthesis, suggesting that altered redox status down-regulates the citric-acid cycle, sparing fatty acids for triglyceride and ketone body production [11].
• Transport of calcium ions across membranes and against a thermodynamic gradient is essential to many biological processes, including muscle contraction, the citric acid cycle, glycogen metabolism, release of neurotransmitters, vision, biological signal transduction and immune response [12].
• A similar icatibant-sensitive enhancement of citric acid-evoked cough was seen in untreated animals after prior inhalation of bradykinin, although cough evoked by hypertonic saline was unaffected [13].
• Treatment of guinea pigs for two weeks with captopril led to an increased cough response to inhaled citric acid, which was prevented by concomitant treatment with the bradykinin receptor antagonist icatibant [13].

Chemical compound and disease context of citric acid

• Two-dimensional polyacrylamide gel electrophoresis of the acid-soluble nuclear proteins of the AH-66 hepatoma nuclei isolated by the cetylpyridinium chloride procedure as well as by the citric acid procedure revealed that Spots Ac and C16-C18 were significantly intense in the gel pattern [14].
• Control of flux through the citric acid cycle and the glyoxylate bypass in Escherichia coli [15].
• Restitution of cerebral energy state, as well as of glycolytic metabolites, citric acid cycle intermediates and associated amino acids after 30 minutes of complete ischemia in rats anaesthetized with nitrous oxide or phenobarbital [16].
• Functions of the membrane-associated and cytoplasmic malate dehydrogenases in the citric acid cycle of Escherichia coli [17].
• Clostridium botulinum type A spores were inoculated at a level of 10(7) spores per ml into sterile beef media with protein concentrations of 1, 2, 3, 4, or 6% and acidified to pH values of 2.01 to 4.75 with hydrochloric acid or 4.19 to 4.60 with citric acid [18].

Biological context of citric acid

• Mitochondria are indispensable for cell viability; however, major mitochondrial functions including citric acid cycle and oxidative phosphorylation are dispensable [19].
• The results suggest that Tor proteins directly modulate the glucose activation and nitrogen discrimination pathways and the pathways that respond to the diauxic shift (including glycolysis and the citric acid cycle) [20].
• The recent discovery of two IRE-regulated mRNAs encoding enzymes of the mitochondrial citric acid cycle may represent the beginnings of elucidating regulatory coupling between iron and energy metabolism [21].
• Injury up- and down-regulated gene clusters also were distinctive, prominently implicating glycolysis-related genes and citric acid cycle/oxidative phosphorylation/redox-mitochondrial functions, respectively [22].
• Coordination of citric acid cycle activity with electron transport flux [23].

Anatomical context of citric acid

• We hypothesized that the apparent defect in energy production results from a depletion of the catalytic intermediates of the citric acid cycle via leakage through cell membranes (cataplerosis) [24].
• A concentration of 1.0 mM Ca2+ provided the highest cell yield for prolonged growth as determined by the enumeration of cell nuclei isolated by citric acid [25].
• A major polypeptide of M(r) 37,000 was purified from a desmosome-enriched citric acid-insoluble pellet of pig tongue epithelium [26].
• Citric acid was highly effective in removing the outer nuclear membrane (ER) with concomitant reduction (< 10-fold) of mannose-6-phosphatase activity, but not p93 [27].
• These studies indicate that leucine as well as a variety of substrates that are oxidized in the citric acid cycle are involved in regulation of protein turnover in heart muscle [28].

Associations of citric acid with other chemical compounds

• These structures were further fractionated by the use of various treatments including sonication, sucrose gradient centrifugation, and extraction with buffers containing high concentrations of salt, urea, citric acid, or detergents [29].
• The effect of hyperoxia on activity of the superoxide-sensitive citric acid cycle enzyme aconitase was measured in cultured human epithelial-like A549 cells and in rat lungs [30].
• The mean latency of the response to citric acid after chewing miracle fruit was essentially the same as that for sucrose and was 250-300 ms longer than that for citric acid [31].
• Pyruvate has been estimated to enter the citric acid cycle in islets by carboxylation to the same extent or more than by decarboxylation [32].
• This includes inhibition of DNA synthesis, two oxidoreductases of the mitochondrial electron transport chain (NADH: ubiquinone oxidoreductase and succinate: ubiquinone oxidoreductase), and the citric acid cycle enzyme aconitase [33].

Gene context of citric acid

• HOG1 was also required for citric acid-induced up-regulation of Ssa1p and Eno2p [34].
• HOG1 negatively regulated the expression of a number of proteins in response to citric acid stress, including Bmh1p [34].
• In addition, deletion of BMH2 rendered cells sensitive to citric acid [34].
• To counteract the cation chelating activity of citric acid, the plasma membrane Ca(2+) channel, CCH1, and a functional vacuolar membrane H(+)-ATPase were found to be essential for optimal adaptation [34].
• Supporting this, Mdh1p and Idh1p, both TCA cycle enzymes, were up-regulated in response to citric acid [34].

Analytical, diagnostic and therapeutic context of citric acid

• In the second study, using positron emission tomography, we compared regional cerebral blood flow (rCBF) in a condition in which citric acid was presented with one in which water was presented (with similar somatosensory stimulation across both conditions) [35].
• In the first experiment, elevated citric acid recognition thresholds, but normal detection thresholds, were observed in a group of patients who had undergone a right anterior temporal lobectomy for the treatment of epilepsy, compared with a control group and a group of patients who had undergone the same operation in the left hemisphere [35].
• Mathematical analysis of isotope labeling in the citric acid cycle with applications to 13C NMR studies in perfused rat hearts [36].
• A citric acid solution is an optimal test drink in the 13C-urea breath test for the diagnosis of Helicobacter pylori infection [37].
• Zidovudine concentrations were determined in plasma, unstimulated mixed saliva and citric-acid-stimulated mixed saliva over a period of 3 1/2 hours by high-performance liquid chromatography [38].

References