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Biomedical subjects

M Ray

Publications and source records attributed to M Ray.

At least 145 records · Page 8Linked to original sources
PubMed1986

Analysis of replication patterns in chromosomes of normal Chinese hamster and its cell lines.

Replication patterns of the normal male Chinese hamster chromosomes and the three cell lines CHW, 1102 and 1103, were determined using fluorescent, plus Giemsa or acridine orange, techniques. The individual chromosomes or chromosomal segments were consistent in the replication patterns of normal Chinese hamster chromosomes and all the transformed cell lines. Late DNA replication was regularly identified in the long arm of the X chromosome, the entire Y chromosome, the short arms of chromosomes 6 and 7, and the paracentromeric regions of chromosomes 8, 9 and 10. A similar consistency was demonstrated in the large late replicating areas of chromosomes X and Y. Each cell line had specific marker chromosomes by which the cell line was identified and their replication patterns have been described. The chromosome analysis in cell line 1103 indicated that chromosomes 2, 3, 8 and 9 were more stable than others, of which chromosome 2 was extremely stable. The markers M4 and M5 in cell line 1103 are very interesting. The cytogenetic behaviour of marker M4 indicated a new phenomenon of translocation by simple association. The marker chromosome M5 indicated that inactivation spread to the early replicating distal region. These cell lines are very useful tools for studying replication patterns and providing a basic understanding of mammalian cytogenetics.

Animals↗
PubMed1985

L-Threonine dehydrogenase from goat liver. Feedback inhibition by methylglyoxal.

L-Threonine dehydrogenase, which forms aminoacetone from L-threonine and NAD, has been extensively purified from goat liver. A feedback inhibition of this enzyme has been observed with methylglyoxal. Kinetic data and other experiments indicate that methylglyoxal acts at a site other than the active site of the enzyme. The enzyme contains a single subunit of Mr 89,000. The apparent Km values of the enzyme for L-threonine and NAD were found to be 5.5 and 1 mM, respectively.

Alcohol Oxidoreductases↗
PubMed1985

Colitis cystica profunda: presenting with complete intestinal obstruction and recurrence.

An unusual case of colitis cystica profunda is described. The patient presented with intestinal obstruction due to a polypoid mass in the descending colon, which was diagnosed as colitis cystica profunda after the patient underwent colectomy. Three other separate lesions were present in the ascending, transverse, and sigmoid colon. There was no antecedent or associated colonic disease. The disease recurred 1 yr later in the remaining colon and rectum.

Cecum↗
PubMed1985

A case of de novo trisomy 12p syndrome.

We described a case of complete trisomy 12p syndrome (non-mosaic) originating de novo in a first born child to healthy 26 year old nonconsanguineous parents. The 12p syndrome has been confirmed by clinical, cytogenetic and gene dosage studies.

Abnormalities, Multiple↗
PubMed1984

Purification and partial characterization of a methylglyoxal reductase from goat liver.

An enzyme which catalyzes the reduction of methylglyoxal to lactaldehyde has been isolated and purified from goat liver to apparent homogeneity. NADH was found to be a better substrate than NADPH for methylglyoxal reduction. Stoichiometrically equivalent amounts of lactaldehyde and NAD are formed from methylglyoxal and NADH. Enzyme activity was located only in the soluble supernatant fractions of liver cells. Of the various carbonyl compounds tested, methylglyoxal was found to be the best substrate. The pH optimum of the enzyme was found to be 6.5, and Km for methylglyoxal was 0.4 mM. The molecular weight of the enzyme was found to be 89000 by gel filtration on a Sephadex G-200 column. Electrophoresis on sodium dodecyl sulfate-polyacrylamide gel revealed that the enzyme is composed of two subunits. The enzyme is highly sensitive to sulfhydryl group reagents. The inactivation by p-chloromercuribenzoate could be substantially protected by methylglyoxal in combination with NADH, indicating a possible involvement of one or more sulfhydryl group(s) at the active site of the enzyme.

Alcohol Oxidoreductases↗
PubMed1984

Oxidation of lactaldehyde by cytosolic aldehyde dehydrogenase and inhibition of cytosolic and mitochondrial aldehyde dehydrogenase by metabolites.

An enzyme fraction which oxidizes lactaldehyde to lactic acid has been purified from goat liver. This enzyme was found to be identical with the cytosolic aldehyde dehydrogenase. Lactaldehyde was found to be primarily oxidized by this enzyme. Almost 90% of the total lactaldehyde-oxidizing activity is located in the cytosol. Methylglyoxal and glyceraldehyde 3-phosphate were found to be strong competitive inhibitors of this enzyme. Aldehyde dehydrogenase from goat liver mitochondria has also been partially purified and found to be strongly inhibited by these metabolites. The inhibitory effects of these metabolites on both these enzymes are highly pH dependent. The inhibitory effects of both the metabolites have been found to be stronger for the cytosolic enzyme at pH values higher than the physiological pH. For the mitochondrial enzyme, the inhibition with methylglyoxal was more pronounced at higher pH values, whereas stronger inhibition was observed with glyceraldehyde 3-phosphate at physiological pH.

Aldehyde Dehydrogenase↗
PubMed1984

Control of measles by annual pulse immunization.

In a village with a population of more than 2,000, with measles outbreaks in alternate years, annual single-day measles immunization campaigns were conducted during four winter seasons. Measles vaccine was offered to children 1 year of age and older, with no previous measles or immunization. There has been no outbreak of measles since the introduction of immunization to date. Four cases of introduced measles did not result in any secondary case. This vaccine delivery strategy (annual pulse immunization), designed to improve coverage and simplify cold chain management, was shown to be suitable for the control of measles in rural communities in the Third World.

Child↗
PubMed1984

Interstitial deletion of the short arm of chromosome 4.

A 17 year old girl investigated for mental retardation and minor anomalies was found to have an interstitial deletion of 4p. Her clinical and cytogenetic findings are compared with previous reported case of interstitial 4p deletion and with terminal 4p--deletions (Wolf-Hirschhorn syndrome).

Abnormalities, Multiple↗
PubMed1983

In vivo generation and selection of variants with altered sensitivity to natural resistance (NR): a model of tumor progression.

The stability of a cloned murine tumor for sensitivity to NR was examined following growth in vivo in order to test the hypothesis that tumor progression proceeds through the generation and selection of variants. Clonal sensitivity to the [131I]-dUrd elimination assay of NR was assessed for the L5178Y-F9 tumor grown in syngeneic DBA/2 mice or maintained solely in tissue culture. Subclones derived from a tumor obtained from the injection site 3 1/2 weeks after the s.c. inoculation of 25 cells were less sensitive to NR in comparison with subclones derived from cells grown only in vitro. Subclones from the cells grown in vivo exhibited increased heterogeneity in sensitivity to NR in addition to their expanded range of susceptibility to complement-mediated lysis by CBA serum natural antibodies. The extent of the heterogeneity argues against tumor "adaptation" forming the basis for the phenotypic alteration while chromosomal studies eliminate the possibility that a new tumor was induced. These data support the hypothesis that tumor progression proceeds through the random generation of variants and host-mediated selection for the proliferation of clones with an increased ability to survive.

Animals↗
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↗