PubMed Health⌕ Search

Biomedical subjects

M Ray

Publications and source records attributed to M Ray.

At least 163 records · Page 9Linked to original sources
PubMed1983

Control of poliomyelitis by pulse immunisation in Vellore, India.

In a simple study into the control of polio in the Third World a town was divided into 16 zones and pulses or oral polio vaccine given at one station in each zone, after extensive publicity about the campaign. Some 62% of children received three doses of the vaccine and the incidence of polio fell dramatically over the study period. It is suggested that this method is applicable to similar communities because it is cheap, effective, and able to be extended to unimmunised communities when resources allow.

Child, Preschool↗
PubMed1983

Role of ions in activation of human lymphocytes.

Phytohemagglutinin (PHA)-stimulated lymphocytes were cultured in media containing varying levels of K+, Mg2+, Ca2+. Cell activation was monitored by measuring nuclear diameter and by evaluating the area of nucleolus which reacted with silver nitrate. Decreasing extracellular K+ from normal levels (5.0 mM) to 14% (0.7 mM) and decreasing extracellular Mg2+ from normal levels (1.0 mM) to 14% (0.14 mM) did not affect nuclear diameter or silver nitrate reactivity of PHA-stimulated lymphocytes. Chelation of extracellular Ca2+ with EGTA during the first 24 h after PHA stimulation completely inhibited the increases in silver reactivity and nuclear diameter associated with stimulation. Chelation of extracellular Ca2+ 48 h after PHA stimulation did not inhibit lymphocyte stimulation. Inhibitory effects of EGTA were completely reversed if CaCl2 was added to the medium within 24 h of PHA stimulation. By 48 h the effects were irreversible.

Calcium↗
PubMed1983

Sister chromatid exchange response of various human and mouse tissues to MMC and BrdU.

The effect of two known mutagens on different human and mouse tissues was examined in an attempt to determine if tissue specific responses exist. The tissues included human lymphocytes, skin fibroblasts, ovarian and testicular cells, as well as mouse kidney, lung, ovarian and testicular cells. All cell types were exposed to varying concentrations of 5-bromodeoxyuridine (BrdU), and mitomycin C (MMC). The numbers of SCEs (sister chromatid exchanges) were recorded from each tissue. Results seemed to indicate that certain of the tissues tested appeared more sensitive to particular test agents. Human ovarian and skin fibroblasts appeared more sensitive to MMC, whereas lymphocytes and skin fibroblasts appeared more sensitive to BrdU. Mouse tissues showed little or no response over the test concentration ranges of both MMC and BrdU. A human ovarian cell sample karyotyped as 44,XX,t(14;21)(p11;q11),t(14;21)(p11;q11) was tested with both agents and was found to have fewer SCEs in response to varied MMC concentrations than ovarian cells carrying the normal 46,XX karyotyped. Results appeared to suggest in human cells that an intra-individual tissue specific response to mutagens may exist.

Animals↗
PubMed1983

Sister chromatid exchange distribution in various human tissues exposed to MMC and BrdU.

The effect of two known mutagens on different human tissues was examined in an attempt to determine if tissue specific responses exist in SCE distribution on chromosome. The tissues included human lymphocytes, skin fibroblasts, ovarian and testicular cells. All cell types were exposed to varying concentrations of 5-bromodeoxyuridine (BrdU), and mitomycin C (MMC). The numbers of SCEs were recorded from each tissue. Results indicated that certain of the tissues tested appeared more sensitive to particular agents. Results also showed that in all the tissues tested the larger chromosomes in groups A to C had greater numbers of SCEs than did the smaller chromosomes in groups D to G. There were very few SCEs in F and G group chromosomes including Y.

Bromodeoxyuridine↗
PubMed1983

Methylmercury toxicity: in vivo evaluation of teratogenesis and cytogenetic changes.

Mercury is a major environmental pollutant and a proven teratogen in both animals and man. Different dose levels of methylmercuric chloride (30, 25, 15 and 5 mg/kg of body weight) were administered to pregnant ICR strain mice on day 9 of pregnancy. On gestational day 18 the animals were laparotomized. A significant increase in fetal toxicity was observed at all dose levels, except following treatment with 5 mg/kg. A marked reduction in the mean weight of fetuses from treated animals (5 mg/kg) was observed compared to the controls. Higher levels of mercury were found in maternal blood and in fetal tissues of treated animals compared to the corresponding controls. Chromosome stickiness and clumping were observed in all tissues examined (e.g., bone marrow, spleen, lung, liver) from the fetuses of treated animals. The frequency of SCEs'/cell in bone marrow cells was similar to that of controls. The results demonstrate that methylmercuric chloride, the most toxic of mercuric compounds, causes chromosome stickiness and clumping leading to reduced mitotic divisions.

Abnormalities, Drug-Induced↗
PubMed1982

Purification and characterization of NAD and NADP-linked alpha-ketoaldehyde dehydrogenases involved in catalyzing the oxidation of methylglyoxal to pyruvate.

Two alpha-ketoaldehyde dehydrogenases, one catalyzing the oxidation of methylglyoxal to pyruvate with NAD and the other with NADP, were isolated from goat liver and happened to be co-purified. Both the enzymes had been extensively purified to the point where only these two enzymes were present. By affinity chromatography on a thiol-Sepharose column, the two enzymes were separated. Molecular weight of both the enzymes was found to be 42,000 by gel filtration in a Sephadex G-200 column. Electrophoresis on sodium dodecyl sulfate-polyacrylamide gel revealed that the enzymes are composed of single subunits. Interaction with mercurials indicated the presence of SH group(s) in the active site of the NAD-linked enzyme only.

Aldehyde Oxidoreductases↗
PubMed1982

On the interaction of nucleotides and glycolytic intermediates with NAD-linked alpha-ketoaldehyde dehydrogenase.

The effect of different nucleotides and glycolytic intermediates was tested on the NAD-linked and NADP-linked alpha-ketoaldehyde dehydrogenases involved in the oxidation of methylglyoxal to pyruvate. ATP, GTP, and ADP strongly inhibit the NAD-linked enzyme whereas activity of the NADP-linked enzyme remained unaltered. NADP at a concentration much below its catalytic concentration strongly inhibited the NAD-linked enzyme. This NADP inhibition decreased with decreasing of the pH of the incubation medium. Fructose 1,6-bisphosphate stimulated and glyceraldehyde 3-phosphate inhibited the activity of the NAD-linked enzyme whereas dihydroxyacetone phosphate inhibited NADP-linked activity. The stimulatory effect of fructose 1,6-bisphosphate diminished with lowering of the pH value. The various effects by several key metabolites of the glycolytic pathway indicate a possible physiological role for these enzymes.

Adenosine Diphosphate↗
PubMed1982

Homozygous Robertsonian translocations in a fetus with 44 chromosomes.

We report the unique finding of a human fetus with 44 chromosomes with homozygous 14;21 translocations. This fetus appeared phenotypically normal but the long-term neurodevelopmental outcome had this pregnancy continued could not be predicted. We speculate one 14;21 translocation was inherited from her father and one arose de novo being maternal in origin. A previous sibling with psychomotor retardation has an abnormal chromosome complement of 45,XX,dup(7)(q21 leads to pter), t(14;21)(p11;q11). The mother's underlying disease, systemic lupus erythematosis (SLE), and her prior chemotherapy may have contributed to the appearance of these chromosome aberrations. It is interesting that although 14;21 translocations are among the commonest structural chromosome rearrangements in man, there are no previous reports in newborn surveys of a child with 44 chromosomes resulting from the mating of two identical Robertsonian translocation carrier parents.

Abortion, Therapeutic↗
PubMed1982

Dipyridamole test in angina pectoris: diagnostic value and pathophysiological implications.

The value of the dipyridamole test (0.75 mg/kg i.v.) in the diagnosis of angina pectoris was studied in 54 patients with angina pectoris (35 with angina on effort associated or not associated with rest angina and 19 with angina only at rest) and in 12 control subjects. The test induced electrocardiographic signs of ischemia (positive test) in 74% of patients with angina on effort, while it was negative in all cases with angina only at rest and in control subjects. All anginal patients with normal coronary arteries or less than 50% stenosis had a negative test; a positive response was observed in 36, 79 and 60% of cases with one-, two-or three-vessel disease, respectively. Hemodynamic changes with a marked arteriolar vasodilatation were observed both in the negative and in the positive tests. In the positive tests no significant change of double product, blood pressure and left ventricular end-diastolic pressure occurred before ischemia appeared. The results of the study show that dipyridamole as a diagnostic test in angina pectoris has a high specificity but a lower sensitivity than exercise test. The hemodynamic and eletrocardiographic findings in the positive tests suggest that dipyridamole-induced ischemia is due to a flow maldistribution with selective subendocardial ischemia secondary to the coronary arteriolar dilatation caused by the drug.

Adult↗
PubMed1981

Isolation of methylglyoxal synthase from goat liver.

An enzyme fraction which specifically catalyzes the formation of methylglyoxal from dihydroxyacetone phosphate has been isolated and partially purified from goat liver. The enzyme fraction appears to be substantially free from glyoxalase I, reduced glutathione, and triosephosphate isomerase. Approximately equimolar quantities of methylglyoxal and inorganic phosphate were obtained from dihydroxyacetone phosphate. Formation of methylglyoxal was confirmed by colorimetric and enzymatic estimations as well as by paper chromatography and its spectrum. Glyceraldehyde-3-phosphate, fructose 1,6-bisphosphate, dihydroxyacetone, and glyceraldehyde, failed to act as substrates. The enzyme is inhibited by some phosphorylated compounds and inorganic phosphates.

Animals↗
PubMed1981

Tachycardia-dependent and bradycardia-dependent intraventricular conduction defects in acute myocardial infarction: electrocardiographic, electrophysiologic, and clinical correlates.

Presence of rate-dependent (RD) intraventricular conduction defects (IVCD) was documented by inducing variations in heart rate in 30 acute myocardial infarction (AMI) patients (10 right bundle branch block, six left bundle branch block, 13 left anterior hemiblocks, and two left posterior hemiblocks). Five IVCDs were tachycardia-dependent (TD), 20 were bradycardia-dependent (BD), and six were both TD and BD. In TD blocks shortest cycles showing normal intraventricular conduction ranged from 410 to 1330 msec (697 +/- 84 SE); in BD blocks longest cycles with normal intraventricular conduction ranged from 450 to 1450 msec (962 +/- 52). In 60% of cases intermittent incomplete RD blocks were also present. In one patients RD-IVCD intermittency remained until discharge; in the others it lasted from 4 minutes to 10 days. Afterwards 19 RD-IVCDs disappeared and four became stable; six patients died during RD-IVCD intermittency period. Disappearance of RD block was preceded by gradual reduction in cycle length showing TD block and lengthening of cycles stopped beats with BD block. Serial observation of RD-IVCDs provides information about sequence of electrophysiologic effects on the intraventricular conduction system in clinical AMI.

Acute Disease↗
PubMed1981

Transcriptional control in the production of liver-specific mRNAs.

cDNA clones complementary to liver mRNA were prepared and used to determine transcription rates of specific genes in isolated nuclei from liver, brain, and hepatoma cells. The cDNA sequences complementary to mRNA found only (or mainly) in the liver hybridize to labeled nuclear RNA only from liver nuclei. It appears that transcriptional events are primarily responsible for the synthesis of these, and perhaps most, tissue-specific moderately abundant mRNAs.

Animals↗
PubMed1980

Presence of two conformationally vicinal sulfhydryl groups at the active site of UDP-glucose 4-epimerase from Saccharomyces fragilis.

UDP-glucose 4-epimerase from Saccharomyces fragilis was inactivated by diazene dicarboxylic acid bis-N,N-dimethylamide or diamide, a compound that can specifically oxidize conformationally vicinal sulfhydryl groups on protein surfaces. The inactive enzyme was shown to retain the original dimeric structure and NAD, which is a coenzyme for this reaction, was not dissociated from the apoenzyme. The loss of activity was due to the direct modification of sulfhydryl groups and could not be attributed to any subsequent loss of structural integrity. The activity of the enzyme could be regained almost completely on incubation with mercaptoethanol alone and no exogenous NAD was needed for reactivation. The reactivated enzyme showed most of the characteristic properties of the native enzyme like activation by cations or inhibition by UMP. Presence of substrate provided partial protection against inactivation by the reagent. Formation of disulfide bond(s) across the subunits was demonstrated by sodium dodecyl sulfate gel electrophoresis in absence of mercaptoethanol. Titration of native and diamide-inactivated enzyme with p-chloromercuribenzoate revealed that only two sulfhydryl groups were involved in the formation of the disulfide cross-linkage across the subunits. The above results indicate the possible presence of two conformationally vicinal sulfhydryl groups at two different subunits of the enzyme that constitute part of the active site.

Binding Sites↗
PubMed1980

Fluorescence properties of reconstituted forms of UDP-glucose 4-epimerase from Saccharomyces fragilis.

UDP-glucose 4-epimerase from Saccharomyces fragilis exhibits a very characteristic intense fluorescence with an excitation maximum at 360 nm and an emission maximum at 433 nm. The fluorescence spectrum resembles the fluorescence of free NADH with an apparent blue shift and, although the exact nature of the fluorophore is not known, the protein-bound NAD, which is a coenzyme for this reaction, or its reduced form is obviously involved in the emission of the fluorescence. The fluorphore therefore constitutes part of the active site. The inactivation of epimerase with diazinedicarboxylic acid bis(N,N-diethylamide), a reaction shown in the previous paper to form a disulfide linkage across the subunits, results in a simultaneous and correlated loss of the characteristic fluorescence of the enzyme. Reaction with mercaptoethanol restores the native fluorescence with a 2 nm blue shift in emission maximum. These epxeriments provide additional evidence that the two conformationally vicinal sulfhydryl groups are located at the active site. Unlike the reconstituted enzyme obtained from the diamide-inactivated enzyme, the partialy active enzymes reconstituted from p-chloromercuribenzoate-inactivated and heat-inactivated enzymes fail to show the reappearance of the characteristic native fluorescence. Treatment with N-ethylmaleamide, on the other hand, leads to a form of the inactive enzyme that fully retains its fluorescent properties. A model depicting the minimal changes at the active site during the process of inactivation and reconstitution by these various treatments is presented.

Carbohydrate Epimerases↗