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Biomedical subjects

M Ray

Publications and source records attributed to M Ray.

At least 55 records · Page 3Linked to original sources
PubMed1987

Aminoacetone oxidase from goat liver. Formation of methylglyoxal from aminoacetone.

An enzyme which oxidizes aminoacetone to methylglyoxal has been purified from the particulate fraction of goat liver. Polyamines, such as spermidine and spermine, are also good substrates for this enzyme. The pH optimum for aminoacetone oxidation was found to be 8.2. The apparent Km values of the enzyme for aminoacetone and spermidine were 0.009 and 0.095 mM, respectively. The subunit molecular weight of the enzyme was 93,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The apparent molecular weight of the native enzyme was 186,000 by gel filtration. The enzyme is highly sensitive to carbonyl group reagents. The enzyme is not inhibited by monoamine and diamine oxidase inhibitors.

Acetone↗
PubMed1987

Light and electron microscopic study of fetal lung following maternal exposure to methylmercuric chloride.

Varying dose levels of methylmercuric chloride (MMC), 1000 ppm (5 mg through 15 mg/kg of body weight), were administered via an intragastric tube to pregnant ICR Swiss/Webster mice on day 9 of gestation. The animals were killed on gestational day 18 and the fetuses removed. Fetal lung sections were processed for light and electron microscopy. A group of animals treated with physiological saline in a similar manner served as the controls. The fetal lungs from treated animals were hypoplastic and retarded in development. The severity of pulmonary changes increased with the dose-levels of MMC. Vacuolation and lysis of mitochondria were seen in fetal lungs. Mitochondrial damage increased in severity with dose-level of methylmercuric chloride.

Animals↗
PubMed1987

Cytostatic action of methylmercuric chloride on mammalian duodenal cells.

Adult male mice of the ICR/Swiss Webster strain received a single intragastric administration of methylmercuric chloride 1,000 ppm, at dose levels of 5,10,15,20,25 and 30 mg/kg of body weight. The animals were killed six hours later. Tissue samples from the duodenum were fixed in 10% neutral buffered formalin for light microscopy. Chromosome clumping was observed in dividing cells at all dose levels, resembling a C-mitotic effect. It would lead to reduced mitotic cell formation on account of the subsequent lysis of the arrested metaphases. The cytostatic effect was brought about by the inactivation of the microtubule spindle fiber polymerization mechanism induced by methylmercuric chloride. There was a direct positive correlation between the varying dose levels of methylmercury and the proportion of cells arrested in metaphase in the crypts of the duodenum.

Administration, Oral↗
PubMed1986

Relative bioavailability of a new transdermal nitroglycerin delivery system.

The purpose of this study was to measure the bioavailability of nitroglycerin from a new transdermal delivery system, Nitro-Dur II, relative to that of Nitro-Dur. Twenty-four healthy male volunteers completed a two-way crossover study. Each subject randomly received Nitro-Dur (I) and Nitro-Dur II (II) for a 24-h period. Both transdermal systems had an active surface area of 20 cm2. Blood samples were collected immediately before treatment, at 0.5, 1, 2, 3, 4, 6, 8, 12, 18, and 24 h after topical application of the units, and 30 min after the units were removed. Nitroglycerin was determined with an analytical sensitivity of 50 pg/mL using gas chromatography with electron capture detection (GC-EC). Mean steady-state concentrations of nitroglycerin were 182 and 224 pg/mL for I and II, respectively. There were no statistical differences between I and II in the pharmacokinetic parameters measured (Css, AUC, Cmax, % fluctuation). Residual nitroglycerin content was measured in each transdermal unit after application to each of the 24 volunteers. The amounts of nitroglycerin delivered by I and II were 9.78 +/- 4.11 and 10.67 +/- 4.78 mg, respectively, or approximately 10 mg in 24 h. Statistical analysis of these data using an analysis of variance indicated no significant difference between these treatments (p = 0.27). Since there were also no differences in the plasma concentrations and pharmacokinetic parameters calculated after treatment with I and II, the bioequivalence of the two delivery systems was established.

Administration, Cutaneous↗
PubMed1986

Distribution of sister chromatid exchanges in chromosomes of normal Chinese hamster and its cell lines exposed to BrdU and MMC.

Sister chromatid exchanges (SCEs) were investigated in chromosomes from normal male Chinese hamster (CH) and its cell lines (CHW, 1102 and 1103). The fibroblasts were grown for two replication cycles in medium containing BrdU and mitomycin C (MMC) at concentrations of 0.01, 0.02 and 0.03 micrograms/ml of medium. The difference in SCEs/cell between male CH and CHW was negligible, but the difference between CHW and 1102 was about 2.6-fold. It is suggested from karyotypic differences between CHW and 1102, that the control of SCEs might be due partly or completely to chromosome 5 in Chinese hamster. The lines CHW and 1102 were less responsive than normal Chinese hamster cells when exposed to different MMC concentrations. It is suggested that the lines CHW and 1102 might be slightly resistant to MMC. The frequency of SCEs decreased with the decrease of chromosome size. SCEs are not preferentially distributed on any autosomal chromosomes. No SCEs were found in normal X-chromosomes. The majority of exchanges appear to be either interband regions or very near band-interband junctions.

Animals↗
PubMed1979

Nucleolar organizing regions of human chromosomes.

Silver-stained cells from 49 parents with a history of several abortions were compared with cells from 35 parents with normal liveborn children. The modal and mean number of silver-stained NORs (Ag-NORs) observed on D- or G-group chromosomes was similar in both groups and between males and females. Ag-NORs were randomly distributed on all five acrocentric pairs. The distribution and size of Ag-NORs within an individual was not random and was fairly consistent from cell to cell. The mean number of associations per cell was similar in both males and females of the abortion group and was less than the number of associations in controls. The probability of D- or G-group chromosomes being associated was near the expected probability of 0.6 for D-association and 0.4 for G-association. The frequency of association of any chromosome combination did not differ statistically from the expected values, though the number of associations, 15/22, was higher than expected.

Abortion, Spontaneous↗
PubMed1979

Paroxysmal atrioventricular tachycardia involving an anomalous pathway with antegrade unidirectional block.

37 consecutive patients with frequent episodes of palpitation and/or dizziness underwent electrophysiological study. They had no signs of ventricular preexcitation during either sinus rhythm or atrial pacing. In 17 (46%), the supraventricular tachycardia was sustained by a reentry mechanism involving an anomalous AV pathway with unidirectional antegrade block (AV tachycardia). Some findings were accepted to demonstrate the existence of the anomalous pathway (AP) and others, its participation in the reentry circuit. The possible location of the AP was established in 15 cases at the following sites: left lateral in 5 cases, left posterior in 5 cases, left posteromedial in 1 case, right posterior in 1 case, right anterior in 1 case, posterior septal in 1 case, and anterior septal in 1 case. The rate of the AV tachycardia can be influenced not only by the ventriculoatrial interval but also by the other pathways included in the reentry circuit. It may change conspicuously in cases with dual AV pathway and anomalous AV pathway in relation to the modality of antegrade conduction by the AV node.

Adolescent↗
PubMed1979

Nucleolar organizing regions of normal Chinese hamster and CHW cell line chromosomes.

The chromosome preparations from fibroblasts of normal male and female Chinese hamsters and the cell line CHW were stained with AgNO3. The silver stain was usually localized at the telomeres of autosomes. The marker chromosome M1 in the CHW cell line has Ag-NOR near the centre of the long arm, which indicates that either the long arms of two number 5 chromosomes fused at the telomeres or the intact telomeric region of one chromosome fused with one with a deleted telomere. The variation of Ag-NORs' number per cell and Ag-heteromorphism in chromosome number 4 were observed. The Ag-NORs of chromosome number 4 and 5 are in approximately the same position as the positive C-bands and these may play a role in the preservation of heterochromatin.

Animals↗
PubMed1978

UDP-glucose 4-epimerase from Saccharomyces fragilis. Involvement of sulfhydryl group(s) at the active site.

UDPglucose-4-epimerase (EC 5.1.3.2) from Saccharomyces fragilis is inactivated by 0.1 mM 5,5'-dithiobis-(2-nitrobenzoate) in 6 min. Unlike p-chloromercuribenzoate-inactivated or heat-inactivated enzymes, the dithiobisnitrobenzoate-inactivated enzyme retains the dimeric structure and NAD is not dissociated from the protein moiety. Inactivation of the enzyme by dithiobisnitrobenzoate can not therefore be attributed to any subsequent loss of structural integrity or to the detachment of the cofactor from the apoenzyme. The inactivated enzyme can be almost fully reactivated in the presence of mercaptoethanol and characteristic properties of native enzyme are regained. The inactivation by dithiobisnitrobenzoate can be substantially protected by UDPglucose or UDPgalactose indicating a possible critical involvement of one or more sulfhydryl groups at the active site.

Binding Sites↗
PubMed1978

Analysis of DNA replication patterns of human fibroblast chromosomes: the replication map.

A replication map of human fibroblast chromosomes from two diploid human female fibroblast lines, 46,XX and 46,X, del (X)(q13), was determined using the 'fluorescent plus Giemsa' (FPG) technique. Each chromosome was found to stain homogeneously dark when thymidine was incorporated for the entire S phase of that particular cell. As the duration of exposure to thymidine progressively decreased by increasing the incubation time in bromodeoxyuridine, the staining intensity of chromosomes decreased and, concurrently, gaps in the staining began to appear. These gaps coincide with R bands and represent the earliest areas to complete DNA synthesis. As these areas widen and increase in frequency, first Q and G bands appear, and finally C bands. Homologous X chromosomes were easily differentiated by either a comparison of the bands present or their staining intensity. The replication kinetics of the structurally abnormal heterocyclic X chromosome were very similar to those of the normal heterocyclic X chromosome. The X chromosome with deletion of a portion of the long arm was consistently late in replication.

Cell Line↗