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At least 811 records · Page 45Linked to original sources
PubMed1978

Effects of cicloxilic acid on liver subcellular fractions triglyceride content in acute ethanol intoxication.

The action of cis-2-hydroxy-2-phenyl-cyclohexanecarboxilic acid (cicloxilic acid) on the concentration of triglycerides in the subcellular compartments of the liver was investigated in acutely ethanol-intoxicated rats. Cicloxilic acid is able to significantly reduce the accumulation of neutral fats in the homogenate and in the cytosol and to shorten the steatosis regression time. The triglyceride content in total microsomes results slightly higher in the animals treated with cicloxilic acid than in those treated with ethanol only. The data are discussed in relation to the pathogenesis of ethanol fatty liver and to the possible mechanism of action of cicloxilic acid.

Alcoholic Intoxication↗
PubMed2000

Paroxysmal dystonia induced by exercise and acetazolamide.

We report a case of a 40-year-old woman with dystonic attacks precipitated by slight exercise. Episodes lasted 2-5 min and were not precipitated by sudden movements or by being startled, drinking alcohol, coffee or tea, or by stress. Secondary dystonia was ruled out and brain magnetic resonance imaging (MRI) was unremarkable. Routine and video electroencephalogram (EEG) during and between attacks were normal. Acetazolamide greatly worsened her condition, whereas gabapentin [1-(aminomethyl) cyclohexaneacetic acid] treatment markedly reduced the frequency and severity of the episodes.

Acetates↗
PubMed1968

Cross pathway regulation: effect of histidine on the synthesis and activity of enzymes of aromatic acid biosynthesis in Bacillus subtilis.

l-Histidine and, to a lesser degree, l-phenylalanine at concentrations of 10(-4)m inhibit the growth of leaky mutants (bradytrophs) of Bacillus subtilis that are deficient in the synthesis of p-hydroxyphenylpyruvate, the first intermediate specific to tyrosine synthesis. The inhibition can be overcome by growth factor amounts of l-tyrosine and p-hydroxyphenylpyruvate. Histidine and phenylalanine are capable of inhibiting the synthesis of tyrosine in several ways, and the major physiological effect which results in growth inhibition has not been established. Both l-histidine and l-phenylalanine inhibit the activity of prephenate dehydrogenase at concentrations about 100-fold higher than the inhibitory concentration of l-tyrosine. Histidine also appears to repress the synthesis of prephenate dehydrogenase because a histidine bradytroph growing in histidine-supplemented medium has a twofold lower level of this enzyme than the same cells growing in unsupplemented medium. These same two amino acids also inhibit the growth of a bradytroph deficient in dehydroquinate synthetase, an early enzyme in the pathway of tyrosine, phenylalanine, and tryptophan synthesis. The inhibition is overcome by a combination of tyrosine and phenylalanine. Histidine-resistant derivatives of both the prephenate dehydrogenase and dehydroquinate synthetase-deficient strains, which simultaneously have gained resistance to phenylalanine, have been isolated. Most of these resistant mutants synthesize additional tyrosine compared with the parent strain. One class of resistant mutants excretes tyrosine and has a number of enzymes of aromatic acid synthesis which are no longer repressible by any combination of the aromatic amino acids. Tyrosine inhibits the growth of histidine bradytrophs. Histidine, at growth factor levels, overcomes the inhibition.

Bacillus subtilis↗
PubMed1978

Effect of cicloxilic acid on the liver damage produced by a choline-free, high-fat low-protein diet.

The effects of cis-2-hydroxy-2-phenylcyclohexanecarboxilic acid (cicloxilic acid) on the liver damage produced by a choline-free, high-fat low-protein diet (Handler's diet) were studied in rats. Treatment with cicloxilic acid significantly counteracted the increase in liver weight, hepatic lipids, serum transaminase and ornithine carbamoyl transferase activities, caused by the unbalanced and deficient diet. Histological examination of the liver showed a near-normal structure of the hepatic cells in the cicloxilic acid-treated animals. Other antihepatotoxic and choleretic drugs, with which cicloxilic acid was compared, showed either much less protective activity or none at all. Furthermore, while cicloxilic acid (which exhibits choleretic activity) did not alter the hepatic glycogen content, another choleretic drug, 1-phenyl-1-hydroxypentane (PC 1), caused marked depletion. It is concluded that the protective activity exerted by cicloxilic acid on the liver is separable from its choleretic activity.

Animals↗
PubMed2000

Probing the catalytic mechanism of prephenate dehydratase by site-directed mutagenesis of the Escherichia coli P-protein dehydratase domain.

The Escherichia coli bifunctional P-protein, which plays a central role in L-phenylalanine (Phe) biosynthesis, contains distinct chorismate mutase (CM) and prephenate dehydratase (PDT) domains as well as a regulatory (R) domain for feedback control by Phe. To elucidate the catalytic mechanism of PDT in the P-protein, 24 mutations of 15 conserved residues in the PDT domain were created, expressed in the pheA(-)E. coli strain NK6024, and studied for their effect on PDT activity. Fourteen mutant enzymes were purified to homogeneity, tested for feedback inhibition by Phe, and characterized by kinetic analysis and circular dichroism spectroscopy. Selected mutant enzymes were further studied by gel filtration, fluorescence emission, and microcalorimetry. In addition, a monofunctional PDT domain (PDT20, residues 101-285) was cloned and overexpressed in plasmid pET with expression levels up to 200-250 mg/L. PDT20 retained full PDT activity, lacked CM activity, and was insensitive to feedback inhibition by Phe. Four residues (T278, N160, Q215, and S208) were shown to be important for PDT catalysis. The values of k(cat)/K(m) for the S208A/C and T278S mutant enzymes were 100-fold lower, and 500-fold lower for the N160A and Q215A mutant enzymes than the wild-type (WT) protein. The T278A and T278V mutant enzymes displayed no measurable catalytic activity, yet bound both prephenate and a competitive inhibitor (S-DNBA) comparably to the WT protein. These data, taken together with the normal CD spectra of the mutant enzymes, strongly suggested that T278 was involved in the catalytic mechanism. To establish whether acidic residues were involved in catalysis, all the conserved Glu and Asp residues in the PDT domain were mutated to Ala. None of these mutations significantly reduced PDT activity, indicating that the acidic residues of the PDT domain are not directly involved in catalysis. However, two mutant enzymes (E159A and E232A) displayed higher levels of PDT activity (2.2- and 3.5-fold, respectively), which was due to enhanced substrate binding. For the double mutant enzyme (E159A-E232A), k(cat)/K(m) was ca. 7-fold higher than for the WT enzyme, while its K(m) was 4.6-fold lower.

Amino Acid Substitution↗