Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Oxamic Acid”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed1983

Comparative metabolism of chloramphenicol in germfree and conventional rats.

The action of gut microflora on the metabolism of chloramphenicol (CP) was studied in germfree (GF) and conventional (CV) rats after administration of single oral doses of tritiated CP. There were similarities in the metabolic pathways of CP in the GF and CV animals, i.e., rapid absorption, hepatic glucuroconjugation, and biliary excretion of the CP conjugate. CP, CP-oxamic acid, CP-alcohol, and CP-base were present in similar proportions in the urine of both GF and CV rats. Differences observed included the slow elimination of total radioactivity and a reduced proportion of the urinary excretion versus the fecal excretion in the GF Reduction products which were present in much greater quantities in the urine and feces of CV rats are compatible with the generally described hydrolysis of the CP-glucuronide, followed by a nitroreduction of the CP by the gut microflora and the reabsorption of a part of the products formed. In GF rats, CP-glucuronide was the major fecal metabolite, a portion of it having been reabsorbed and excreted in the urine. Although in lesser amounts, reduction products were still present as urinary metabolites in GF rats. Such a reduction in the tissues might produce active intermediate that could be related to CP toxicity.

Animals↗
PubMed1961

Survey of fourteen metabolic inhibitors for their effect on endospore germination in Bacillus subtilis.

Curran, Harold R. (U. S. Department of Agriculture, Washington, D. C.) and Georges Knaysi. Survey of fourteen metabolic inhibitors for their effect on endospore germination in Bacillus subtilis. J. Bacteriol. 82:793-797. 1961.-Phase contrast microscopy was used to study the effects of metabolic antagonists upon incipient spore germination in glucose agar-film microcultures. The period of observation was 1 to 2 hr. Of 14 compounds tested, only ethanol in 10% concentration (v/v) caused almost complete inhibition. Oxamic acid and dl-ethionine were slightly stimulatory; 6-methyl thiouracil and octyl aldehyde were without effect. The inhibiting effect of the remainder depended upon the concentration of the antagonist. The stimulating effect of glucose on germination is discussed.

Antimetabolites↗
PubMed1964

OXAMIC TRANSCARBAMYLASE OF STREPTOCOCCUS ALLANTOICUS.

Bojanowski, R. (University of Illinois, Urbana), Elizabeth Gaudy, R. C. Valentine, and R. S. Wolfe. Oxamic transcarbamylase of Streptococcus allantoicus. J. Bacteriol. 87:75-80. 1964.-An improved colorimetric assay for carbamyl oxamate, which allows the precise measurement of the activity of oxamic transcarbamylase, has been developed. Activity is maximum over the pH range from 8.3 to 8.7. A cation requirement is satisfied by 2.5 x 10(-3)m Mg(++) or Mn(++). The equilibrium constant for the phosphorolysis of carbamyl oxamic acid is 1.6, corresponding to a negative free energy change of -285 cal per mole.

Adenosine Triphosphate↗
PubMed1990

Spreading of trypsinized cells: cytoskeletal dynamics and energy requirements.

The spreading of trypsinized XTH-2 cells (a line derived from Xenopus laevis tadpole heart endothelia) on glass was investigated. Three phases can be distinguished: (1) blebbing of rounded cells, first attachment to a solid substratum and formation of a broad smooth contact area; (2) organization of a peripheral zone of actin fibrils and reinforcement of the basal cytoplasm by a stress fibre-like pattern; (3) extension of lamellae. The first phase seems to be independent of a supply of metabolic energy, while the others clearly depend on it. This is concluded from the close relationship between cellular projection area and energization of mitochondria as revealed by (a) the fluorescence intensity of cells vitally stained with the mitochondria-specific fluorochrome DASPMI (2-4-(dimethylamino)-styryl-1-methylpyridinium-iodine); (b) the degree of spreading in the presence of inhibitors of respiration; (c) effective amelioration of spreading (phases (2) and (3] under conditions of high ATP content. In phase (2) the extension of the central part of the cells becomes stabilized, the cell body settles on the basal cytoplasmic layer and further expansion of the projection area is achieved by lamella formation (phase (3]; motile and stabile regions of the cells become separated. This sequence of events is interpreted as a self-organizing process based on the development of internal hydraulic pressure, actin polymerization and contraction of the newly developed actomyosin network. During trypsinization, depolymerization of actin does not occur but rather on addition of Ca2(+)-containing media. Cellular ATP content drops as well on trypsinization, as on addition of Ca2+. Manganese promotes spreading by decreasing F-actin disassembly and maintaining a high level of cytosolic ATP, most probably because it is not accepted by the calcium pumps. Regarding the association of glycolytic enzymes with F-actin and their influence on actin assembly, lactate dehydrogenase has been inhibited with oxamic acid. This treatment improves the correlation between F-actin content and the degree of spreading; however, the total amount of F-actin remains smaller and the cells spread more.

Actins↗
PubMed1995

Meloxicam: metabolic profile and biotransformation products in the rat.

1. The metabolic fate of 14C-labelled meloxicam was investigated in the urine and bile of rat following oral and intraduodenal administration. Structural elucidation of metabolites was performed by nuclear magnetic resonance, mass spectrometry (electron impact and fast atom bombardment). 2. A mean total of 76.3% 14C-radioactivity was recovered in urine over 96 h, with the remainder in the faeces. The metabolic pattern in the excreta was independent of dose (1 versus 10 mg/kg) and collection period (0-8 versus 24-48 h). In bile one of the main metabolites was absent. 3. Meloxicam underwent extensive metabolism with only small amounts of unchanged drug recovered in the urine (< 0.5%) or bile (4.5%). Principal routes of biotransformation were: oxidation of the 5-methyl group of the N-heteroaryl-carbamoyl side chain to yield the 5'-hydroxymethyl derivative (33% of metabolites in urine, 22% in bile) and the 5'-carboxy derivative (16% in urine, 49% in bile). Oxidative cleavage of the benzothiazine-ring yielded an oxamic acid metabolite in urine (23.5%), which was not present in bile. 4. The introduction of a methyl-group into the N-heteroaryl-carbamoyl side chain increased lipophilicity and facilitated metabolic excretion compared with structurally related compounds.

Animals↗
PubMedDate not supplied

Glutathione-dependent dechlorination of chloramphenicol by cytosol of rat liver.

The 100,000 g supernatant fraction (cytosol) of rat liver converts chloramphenicol (CAP, RNHCOCHCl2) into two products. Most of the enzyme activity is lost during dialysis of the enzyme preparation overnight, but is restored by addition of glutathione (GSH). Other thiols are not as effective as GSH in restoring the enzyme activity. The formation of the metabolites is not inhibited when incubations are performed under anaerobic conditions. The major metabolite was identified as CAP aldehyde (RNHCOCHO) whereas the minor metabolite was identified as an alkali-unstable derivative of CAP oxamic acid (RNHCOCOOH). Plausible pathways are discussed for the formation of these metabolites.

Animals↗
PubMed1980

Metronidazole: proven benefits and potential risks.

Metronidazole is unique among therapies approved for trichomonas vaginitis and is useful also in the treatment of amebiasis, giardiasis and anaerobic bacterial infections. It has recently proved to be effective antibacterial prophylaxis for colon surgery. In spite of these important therapeutic properties the drug is considered risky for human use because of laboratory evidence that is it tumorigenic and mutagenic. A large excess risk of human cancer as the result of prior metronidazole exposure can probably be excluded on the basis of evidence already available. However, with the risk uncertain the drug should be restricted to patients who clearly will benefit from it and these patients should receive the drug in the minimal dose which is effective. Nitro group reduction is implicated in most of the biological properties of metronidazole including its mutagenicity. Two metabolites of the reduction of metronidazole, acetamide and N-(2-hydroxyethyl)-oxamic acid, form in the intestinal flora and can be found in the excreta of conventional rats but not of germfree rats. Thus the worrisome reaction implicated in the mutagenicity of metronidazole occurs in the flora. These metabolites produced by the flora complement those described in Ernest Bueding's laboratory. Bueding's group postulates metabolites which are mutagenic, and thus probably not yet reduced, whereas we postulate that our metabolites indicate that reduction, and thus possibly a mutagenic reaction, has already occurred. The metabolites we describe which are indicative of the reduction of metronidazole are also found in the urine of patients who take the drug. This has several possible implications which bear investigation. One is that a reactive intermediate may form in the flora and enter mammalian tissues. The other is that metronidazole is metabolized in the human to acetamide which is a carcinogen in its own right. Thus this drug,with its increasing number of useful clinical properties, continues to show laboratory properties which have uncertain implications for human risk.

Animals↗
PubMedDate not supplied

Evidence for new metabolic pathways of chloramphenicol in the duck.

Following subcutaneous administration of [3H]chloramphenicol (CP) to duck, HPLC and TLC analyses showed that the two most important metabolites in 0- to 24-hr excreta were CP-oxamic acid and CP-alcohol, which together accounted for about one-third of the radioactivity therein. The remainder was due to unchanged CP (15% dose), CP-base (5% dose), and various metabolites representing < 4% dose each. Among these, CP-glucuronide and CP-sulfate have been previously isolated in mammals. In addition to these metabolites, several previously unreported in vivo CP biotransformation products were identified in this study by HPLC and MS comparison with synthetic reference compounds. These new metabolites were unequivocally identified as 1-O-monoacetyl CP, CP-1,3-diacetate, N-acetyl CP-base, CP-oxamylglycine, and CP-oxamylethanolamine. Besides these formally identified compounds, the CP-phosphate structure was tentatively assigned to a conjugate metabolite resistant to beta-glucuronidase and sulfatase hydrolysis. The possible origin of these metabolites is discussed extensively.

Animals↗
PubMed1978

Origin of nitrogen in the biosynthesis of carbamoylpolyoxamic acid.

The biosynthetic origin of the carbamoylpolyoxamic sidechain of the polyoxin nucleoside peptide antibiotics was studied using 15N labeled alpha-amino-S-hydroxyvaleric acid as precursor. Gas chromatography mass spectrometry of polyoxamic acid isolated from culture filtrates of Streptomyces cacaoi var. asoensis showed incorporation of the nitrogen atom of alpha-amino-S-hydroxyvaleric acid into carbamoylpolyoxamic acid with an isotopic dilution factor of 23, thus establishing the intermediacy of alpha-amino-S-hydroxyvaleric acid and determination of the full biosynthetic pathway.

Amino Acids↗
PubMed1985

Occurrence of succinyl derivatives in the catabolism of arginine in Pseudomonas cepacia.

Pseudomonas cepacia NCTC 10743 utilizes arginine as the sole source of carbon and nitrogen for growth. Arginine is degraded to glutamate via succinyl derivatives. The catabolic sequence in this pathway is L-arginine----N2-succinylarginine----N2-succinylornithine--- -N2-succinylglutamate semialdehyde----N2-succinylglutamate----glutamate + succinate. The formation of the enzymes responsible for arginine degradation is regulated not only by induction but also by both carbon and nitrogen catabolite repression.

Acyltransferases↗
PubMed1987

Allantoin transport in Saccharomyces cerevisiae is regulated by two induction systems.

We show that the allantoin transport system of Saccharomyces cerevisiae responds to two induction systems, one mediated by allophanate or its analog oxalurate and the other mediated by allantoin or its analog hydantoin acetate. The effects of the two inducers were additive in strain M85. Like other allantoin pathway genes, oxalurate-mediated induction of allantoin transport required a functional DAL81 gene product. Hydantoin acetate-mediated induction of the system, on the other hand, occurred normally in dal81 mutants. This suggests that induction was not only mediated by two separate inducers, but also involved different regulatory proteins. Induction is probably a transcriptionally regulated process, because addition of hydantoin acetate or oxalurate to the culture medium increased the steady-state levels of mRNA encoded by a gene required for allantoin transport (DAL4).

Allantoin↗
PubMed1983

H4-isozyme of lactate dehydrogenase in a solution of sodium C chloride--6. The effect of oxalate and oxamate on the molecular weight.

Some differences between the effects of oxalate and oxamate were observed. The oxalate formed the stable tetramers and some aggregates, while the oxamate formed the mixture of dimers, tetramers, octamers and aggregates. The ratios between these molecular forms were different as the oxamate concentration was changed. In the coexistence of inhibitors and pyruvate, pyruvate may act to decrease the molecular weight and to increase the amount of aggregates. The lower molecular weight may be caused by the existence of the active complex, Ed N S1. The effect of the exchange between pyruvate and oxamate bound with enzyme complexes may be expected.

Amino Acids↗
PubMed1985

Inhibition by potential metabolic inhibitors of in vitro adipose tissue lipogenesis.

To study the pathway of lactate utilization as a carbon source for fatty acid synthesis, the effect of (-)-hydroxycitrate, agaric acid, sodium oxamate, 2-n-butyl malonate and alpha-cyano-4-hydroxycinnamate on the rate of in vitro conversion of lactate, acetate and glucose to fatty acids was measured in bovine and rat adipose tissues. Sodium oxamate and hydroxycitrate caused less fatty acid to be synthesized from lactate in bovine adipose tissue. Hydroxycitrate depressed fatty acid synthesis from glucose in rat adipose tissue. alpha-Cyano-4-hydroxycinnamate was an effective inhibitor of lipogenesis from all substrates and may act as a specific inhibitor in adipose tissue. Although the inhibitors were absorbed poorly into adipocytes, the results indicate that conversion of lactate to fatty acids probably occurs by way of the citrate cleavage pathway.

Acetates↗
PubMed1990

Structure of N,N,N',N'-tetrakis(2-fluoro-2,2-dinitroethyl)oxamide by the consistent electron density approach.

C10H8F4N10O18, Mr = 632.22, monoclinic, Pc, a = 7.8885 (6), b = 6.7787 (4), c = 21.595 (2) A, beta = 108.21 (1) degree, V = 1096 (1) A3, Z = 2, Dx = 1.914 g cm-3, lambda(Cu K alpha) = 1.5418 A, mu = 18.7 cm-1, F(000) = 636, T = 293 K, 1791 unique data, 1733 with I greater than 3 sigma (I), R = 0.047. The structure was solved by the consistent electron density approach (CEDA), in which a small starting set of random phases was refined and expanded by the application of restraints to the electron density. A refinable preliminary structure was obtained by fitting a model to a 3 A map, calculated with 27 reflections (all data with d greater than 3 A, and magnitude of Fo greater than 170) whose phases had been determined by the CEDA. The molecule has an extended, open conformation; the two pairs of fluorodinitroethyl substituents located across the molecular center from each other show i and C2 pseudo-symmetry respectively.

Amino Acids↗