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S T Omaye

Publications and source records attributed to S T Omaye.

At least 37 records · Page 2Linked to original sources
PubMed1990

Automated assays for superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activity.

Automated assays for catalase, glutathione peroxidase, glutathione reductase, and superoxide dismutase are presented. The assay for catalase is based on the peroxidatic activity of the enzyme. The glutathione peroxidase and reductase assays measure the consumption of NADPH following the reduction of t-butyl hydroperoxide and oxidized glutathione, respectively. The assay for superoxide dismutase is based on the reduction of cytochrome c. All assays utilize the Cobas FARA clinical automated analyzer and provide considerable time savings over the manual assays.

Animals↗
PubMed1990

Urinary hydroxyproline excretion and vitamin C status in healthy young men.

The relationship between ascorbic acid status and the urinary excretion of hydroxyproline was examined in 11 healthy male subjects fed an ascorbic acid-deficient diet for 14 wk while in a metabolic unit. The diet provided 5 mg ascorbic acid/d and was supplemented with ascorbic acid to give intakes of 65 mg/d (2 wk), 5 mg/d (4 wk), 605 mg/d (3 wk), 5 mg/d (4 wk), and an average 375 mg/d (1 wk). The urinary excretion of hydroxyproline increased by an average of 16% and 30% after the first and second depletion periods, respectively, and decreased to baseline values after supplementation with normal or high doses of vitamin C. Significant (p less than 0.05) inverse correlations were found between urinary hydroxyproline and plasma, red cell, and leukocyte ascorbic acid. These results show that urinary hydroxyproline excretion increases during human vitamin C deficiency but that this effect is not strong enough to provide a reliable marker of mild vitamin C deficiency.

Adult↗
PubMed1989

Comparative distribution, pharmacokinetics and placental permeabilities of all-trans-retinoic acid, 13-cis-retinoic acid, all-trans-4-oxo-retinoic acid, retinyl acetate and 9-cis-retinal in hamsters.

Pregnant hamsters were given a single oral dose (35 mumol/kg) of all-trans-retinoic acid, 13-cis-retinoic acid, all-trans-4-oxo-retinoic acid, 9-cis-retinal or all-trans-retinyl acetate during the early primitive streak stage of development. The radioactivity associated with the acidic retinoids was distributed to all tissues sampled (including placenta and fetus), with the largest accumulation in the liver and the least accumulation in fat. Radioactivity from 9-cis-retinal or retinyl acetate concentrated in the liver and lung. The all-trans-retinoic acid was oxidized in vivo to all-trans-4-oxo-retinoic acid and isomerized to 13-cis-retinoic acid: 13-cis-retinoic acid was oxidized to 13-cis-4-oxo-retinoic acid and isomerized to all-trans-retinoic acid. No parent 9-cis-retinal or retinyl acetate could be detected in maternal plasma. Plasma concentrations of the parent acidic retinoids reached their maxima within 60 min and then followed exponential decay. Of all the retinoids examined here, 13-cis-retinoic acid showed the largest area under the plasma curve, the slowest clearance and the longest elimination t1/2. Total plasma radioactivity, consisting of unidentified metabolites, remained elevated at 4 days after dosing. Maternal peak circulating concentrations of the parent retinoids, total radioactivity, plasma pharmacokinetic parameters or the total concentrations of residual radioactivity in fetal tissues could not be correlated with the differential teratogenic potencies of these retinoids.

Animals↗
PubMed1989

Pharmacokinetics, tissue distribution, and placental permeability of all-trans- and 13-cis-N-ethyl retinamides in pregnant hamsters.

Retinamides have clinical applications in therapy of dermatologic disease, have cancer chemopreventive/chemotherapeutic activities, and possess larger therapeutic ratios than their acidic congeners. The N-ethyl-all-trans-retinamide (NERA) and its 13-cis congener (CNERA) failed to induce terata in hamsters, but an equivalent oral dose of all-trans- or 13-cis-retinoic acid was associated with a significant teratogenic response. Following intubation of 11.4 mg/kg of [3H]NERA or [3H]CNERA to pregnant hamsters during a sensitive stage of development, radioactivity accumulated in maternal bladder and liver. Although plasma concentrations of the parent retinamides declined to nondetectable levels within 12 hr of dosing, near-peak concentrations of retinamide metabolites persisted in maternal plasma until termination of the study (96 hr). Cis/trans isomerization of each retinamide at C13 occurred, but only 15-20% of the total dose could be accounted for as parent retinamide and its C13 isomer. The retinamides were not metabolized to detectable concentrations of circulating all-trans- or 13-cis-retinoic acid. Although the label associated with the retinamides and their biotransformation products crossed the placenta, there was no evidence for preferential accumulation in embryonic or fetal tissues. The results presented here show that the reduced teratogenic potency of retinamides compared to acidic retinoids cannot be ascribed to reduce placental transfer.

Animals↗
PubMed1989

Response of mouse brain to a single subcutaneous injection of the monofunctional sulfur mustard, butyl 2-chloroethyl sulfide (BCS)*.

Exposure to mustard-type vesicants results in alkylation of DNA and vesication. However, the biochemical mechanism for vesicant injury and whether it is localized or diffuse are not clear. We postulated that vesicant damage is mediated by free radicals, resulting in oxidative stress. These free radicals-mediated reactions may propagate systemically distal to the site of exposure. To test this hypothesis, we examined the effects of a single subcutaneous injection of the monofunctional sulfur mustard, butyl 2-chloroethyl sulfide (BCS), on the brain. We injected 3 groups (6 mice/group) of 5-month-old male, athymic, nude mice, weighing 30-35 g, subcutaneously with neat (undiluted) BCS (5 microliters/mouse). After 1, 24, and 48 h, we sacrificed the treated mice along with an untreated control group and analyzed the brains for biochemical markers of oxidative stress. Compared to untreated controls, the activity of glutathione peroxidase increased by 76%, P less than 0.005 at 24 h, and that of glutathione S-transferases by 25-37%, P less than 0.05 over the entire period. Total glutathione content in the brain was significantly lower, 17%, after 1 h and 23% after 24 h. We found also, concomitant with decreased glutathione, almost a 3-fold increase in susceptibility to lipid peroxidation. Because these changes are consistent with oxidative stress, we conclude that the effect of BCS administered subcutaneously may be translocated, reaching mouse brain, and causing oxidative stress.

Animals↗
PubMed1987

An internal standard method for the unattended high-performance liquid chromatographic analysis of ascorbic acid in blood components.

A paired-ion, reversed-phase, high-performance liquid chromatography procedure using electrochemical detection and internal standard quantitation based on isoascorbic acid (IA) is described for the determination of ascorbic acid (AA) in blood cells and plasma. By correcting for vial-to-vial variations in the AA oxidation rate, use of IA as an internal standard overcomes a major problem associated with AA instability and eliminates the necessity of assaying samples immediately after they are prepared for analysis. The ion-pairing agent, dodecyltriethylammonium phosphate, gives improved AA-IA resolution over agents with shorter carbon chains and also eliminates the interference of an unidentified substance extracted with platelet AA. Five percent metaphosphoric acid extracts of mononuclear leukocytes (MN), polymorphonuclear leukocytes (PMN), platelets, or plasma were mixed with the IA internal standard and diluted with an EDTA-cysteine solution. The samples were placed in a refrigerated autosampler at 4 degrees C prior to chromatography on a 5-microns octadecylsilyl column. AA concentrations (mean +/- SD) in platelets, MN, and PMN from six healthy volunteers were 0.25 +/- 0.05, 15.2 +/- 6.28, and 2.43 +/- 1.63 micrograms/10(8) cells, respectively; the mean plasma AA concentration was 0.97 +/- 0.34 mg/dl. All are in good agreement with published values. Refrigerated sample extracts containing the internal standard can be reassayed up to 3 weeks later with negligible change in calculated AA concentration. Up to 70 samples can be assayed per day with a detection limit (3 X SD) and minimum quantifiable level (less than 5% coefficient of variation) of 0.02 and 0.2 ng/injection, respectively.

Ascorbate Oxidase↗
PubMed1987

Biochemical indices of human vitamin C status.

Biochemical indicators of ascorbic acid (AA) status were studied in eleven young adult males fed the same AA deficient diet for 14 wk in a live-in metabolic unit. Supplements of AA were added to the diet to give AA-intake periods of 65 mg/d (2 wk), 5 mg/d (4 wk), 605 mg/d (3 wk), 5 mg/d (4 wk), 605 mg/d (4 d), and 65 mg/d (3 d). Blood plasma, erythrocyte, and leukocyte AA levels all reflected AA intake, however, plasma AA showed less variability than red cell AA levels and was considerably easier to determine than leukocyte AA. Plasma AA values less than 0.40 mg/dL (23 mumol/L) reflected marginal AA status. The daily AA intake calculated to maintain plasma AA levels of at least 0.4 mg/dL (23 mumol/L) in healthy young men was 41 mg. The average AA intake estimated to maximize the total body pool was 138 mg/d. Urine and salivary AA levels were not useful indicators of AA status because urinary AA levels did not discriminate well between adequate and deficient AA intakes and salivary AA levels did not consistently reflect AA intake.

Adult↗
PubMed1987

Effect of varying ascorbic acid intakes on copper absorption and ceruloplasmin levels of young men.

Intestinal copper absorption and blood measures of copper status were studied in healthy young men receiving varying intakes of ascorbic acid (AA) over 14 wk in a live-in nutrition suite. Copper absorption and retention were assessed by measuring absorption of a stable isotope of copper and total fecal copper during four AA intake periods: 2 wk x 65 mg AA/d, 4 wk x 5 mg/d, 3 wk x 605 mg/d and 4 wk x 5 mg/d. Measures of copper status were serum copper and serum ceruloplasmin determined by both enzymatic and immunochemical methods. Copper absorption, copper retention, total serum copper and the serum level of ceruloplasmin protein were not affected significantly by the changes in AA intake; however, the oxidase activity of serum ceruloplasmin was decreased an average of 21% during the high (605 mg/d) AA intake period. The results suggest that in adult men moderate supplemental intakes of AA reduce ceruloplasmin oxidase activity specifically but do not depress intestinal copper absorption or overall body copper status.

Adult↗
PubMed1987

Experimental vitamin C depletion and supplementation in young men. Nutrient interactions and dental health effects.

Biochemical indices of AA clearly showed that the young men in this study were brought into various states of AA depletion and repletion according to their dietary AA intakes. While previous studies have postulated that supplemental intakes of AA may adversely affect body status of vitamins B6 and B12, we found no changes in the B vitamin status of the young men receiving varying AA intakes. Moderate AA supplementation (605 mg/day) showed no antagonistic effect on markers of vitamins B6 and B12. Blood markers of fat-soluble vitamins A and E and iron status were not affected by AA intakes. The propensity of the gingiva to become inflamed or bleed on probing was reduced after normal (65 mg/day) AA intakes as compared to deficient (5 mg/day) intakes and upon supplementary (605 mg/day) AA intakes as compared to normal intakes. The results suggest that AA status may influence early stages of gingival inflammation and crevicular bleeding, and warrant further study of the relationship between AA and periodontal health.

Adult↗
PubMed1987

Measurement of vitamin C in blood components by high-performance liquid chromatography. Implication in assessing vitamin C status.

The fact that platelets, PMN leukocytes, and MN leukocytes concentrate ascorbic acid suggests that vitamin C has an important role in their physiological functions. The question still remains as to which one of the cells best reflects vitamin C status. The ascorbic acid content of PMNs and platelets correlates positively with plasma concentration and supplementation with vitamin C, as shown in Evans et al. They also found that MN leukocytes, in contrast, do not show any such relationship; however, MN leukocytes maintain the highest levels of ascorbic acid and play a very important function in immunocompetence. We have found that with a limited number of subjects, ascorbic acid content of MN and PMN leukocytes correlates positively with plasma ascorbic acid, but there was no correlation between platelets and plasma ascorbic acid (unpublished results). Therefore, further work is necessary to evaluate these three blood components for the best cellular marker of vitamin C status. We have developed a reversed-phase HPLC method for ascorbic acid that can be used in conjunction with our cellular differential centrifugation technique for the determination of ascorbic acid in relatively pure blood cell fractions. The chromatographic method is simple, sensitive, and automated. It clearly resolves ascorbic acid, which is the major form of the vitamin found in vivo and is not prone to interference by sugars, carbohydrates, or nucleotides.

Ascorbic Acid↗
PubMed1987

Dietary ascorbic acid and selenium relationships in the guinea pig.

Plasma-, erythrocyte- and liver Se-dependent glutathione peroxidase (GPx) activity, ascorbic acid (AA) concentration, and erythrocyte and liver Se levels were analyzed in groups of guinea pigs fed a Torula yeast-based semipurified diet supplemented with either O (-AA), 200 (+AA), or 400 (++AA) mg of AA/kg of diet and either 0.05 (+Se) or 0.2 (++Se) ppm of Se for 24 days. Plasma, erythrocyte, and liver AA concentration were directly related to the levels of AA fed. There were 21.2 +/- 2.7% and 51.2 +/- 4.5% (p less than 0.0001) increases in erythrocyte and liver Se, respectively, in ++Se guinea pigs compared to +Se guinea pigs. Dietary AA had no effect on erythrocyte or liver Se levels. Plasma, erythrocyte, and liver GPx specific activities were significantly (p less than 0.001) increased in ++Se guinea pigs compared to +Se guinea pigs. In addition, liver, plasma, and erythrocyte GPx activities were directly related to the level of AA fed. These data indicate that dietary AA has no influence on tissue levels of Se but increases plasma, liver, and erythrocyte GPx activities in the guinea pig.

Animals↗
PubMed1987

Simple method for bleeding the unanaesthetized rat by tail venipuncture.

A technique is described for the intermittent collection of blood from the rat tail. By using commonly available equipment, blood samples can easily be obtained from rats without the need for anaesthesia. The development of this technique makes the rat more readily available as an animal model for repeated withdrawals of small blood samples for pharmacokinetic or bioavailability evaluations.

Animals↗
PubMed1986

Distribution of vitamins A and E in blood and liver of rats depleted of vitamin A or vitamin E.

Young Sprague-Dawley male rats (n = 150) were fed a semipurified diet, either without vitamin A (VA), without vitamin E (VE) or supplemented with both vitamins A and E (control). At the end of weeks 0, 1, 3, 5, 6, 7, 8 and 9, groups of rats were anesthetized with methoxyflurane, and blood was collected by cardiac puncture until the rat was exsanguinated. The liver was excised. Whole blood (WB) from each rat was fractionated into plasma (PLA), leukocytes (LEU), platelets (PLT) and erythrocytes (RBC). Each blood component was extracted with heptane and livers were extracted with CHCl3/CH3OH (2:1, v/v). The extracts were analyzed for VA and VE by high performance liquid chromatography. The relationship among blood components in the loss of VA was PLT = LEU greater than WB greater than PLA. The relationship among blood components in the loss of VE was PLA greater than RBC greater than WB greater than LEU = PLT. VA and VE levels in other blood components decreased precipitously between weeks 0 and 4 in the animals placed on deficient diets. These results and correlation analyses between vitamin contents of blood components and of livers indicate inadequacies for the use of certain blood components as monitors of lipid-soluble vitamin status in the rat.

Animals↗
PubMed1986

Selected pulmonary biochemical and hematological changes produced by prolonged hypoxia in the rat.

Rats were exposed to 12% O2 (1 atm) for 48 hr, then 10% O2 for the duration of the exposures. Significant elevations in enzymes of the glutathione peroxidase system were found in the lungs of rats killed 3.5, 7.5, and 12.5 days of exposure compared to air-breathing controls. Superoxide dismutase was also elevated after hypoxia but nonsignificantly. Animals killed 12.5 days after exposures exhibited 75% (P less than 0.05) more thiobarbituric acid reactive products in their lungs compared to controls. These results along with significant increases of lung lipid peroxidation and in an augmentation of protective antiperoxidative lung defense capabilities. Hypoxia also resulted in enzyme elevations of lung phosphofructokinase and pyruvate kinase, which may indicate an adaptive increase in lung glycolytic capabilities which would be helpful in maintaining lung tissue energy requirements during hypoxia. In addition, it was confirmed that red blood cell count, hemoglobin and hematocrit values increased after prolonged hypoxia. The results of this study might also reflect enzyme elevation/induction due to cellular reparative-proliferative processes following hypoxia.

Animals↗
PubMed1986

A comparison of leukocyte ascorbate levels measured by the 2,4-dinitrophenylhydrazine method with high-performance liquid chromatography using electrochemical detection.

In leukocytes a dynamic relationship between the reduced form of ascorbic acid (AA) and its oxidized product dehydro-AA has been described. It is therefore important to know which form of the vitamin predominates when choosing a methodology. The purpose of this study was to find out if the majority of ascorbate in human leukocytes isolated by centrifugation through Percoll is in the reduced AA form by measuring reduced AA by HPLC and comparing the values to those obtained by using the 2,4-dinitrophenylhydrazine (DNPH) method which measures total ascorbate, and quantifying the reduced and oxidized forms of the vitamin in leukocytes using a modification of the DNPH method. There was no significant difference (P greater than .05) between the HPLC and DNPH values for 12 individuals and 87% of the AA was found to be in the reduced form. These results support the assumption that the majority of AA found in a mixed leukocyte population isolated through Percoll is in the reduced form and that both methods can be used for AA measurements.

Ascorbic Acid↗
PubMed1986

Plasma ascorbic acid in adult males: effects of depletion and supplementation.

We investigated effects of moderately elevated oral doses of ascorbic acid (AS) on plasma AS turnover in healthy men after abrupt alterations in AS intake. Subjects ate a basal diet of conventional food in which only AS intake was changed. Blood specimens were collected from fasted subjects twice each week during depletion periods. Deproteinized plasma was analyzed after derivatization with 2,4-dinitrophenylhydrazine. Subjects remained healthy and never became frankly scorbutic. The kinetics of log-converted plasma AS values for the depletion periods demonstrated that the slopes calculated by least squares were up to 56% higher for six of nine subjects after 600 mg AS/day. The difference between the mean slopes (M) for loss of plasma AS was significantly different (p less than 0.05, n = 6) after 60 mg AS (M = -0.0222 +/- 0.0145) than after 600 mg AS (M = -0.0246 +/- 0.0003). Leukocyte AS concentration decreased 44.6% in the first depletion period and 77.1% in the second.

Adult↗