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Biomedical subjects

G Chapman

Publications and source records attributed to G Chapman.

At least 55 records · Page 3Linked to original sources
PubMed1988

Effects of interferon on natural killer (NK) cells assessed by fluorescent probes and flow cytometry.

The effects of interferon-alpha and -gamma (IFN) on natural killer (NK) cells was investigated by labelling cells with fluorescent membrane and intracellular probes and analysing these by flow cytometry. Peripheral blood mononuclear cells (PBMCs), sorted NK cells and non-NK cells were labelled with one of the fluorescent probes, 3,3'-dihexyloxacarbocyanine (DiOC6(3], N-phenyl-1-naphthylamine (NPN) or Quin 2, subsequent to incubation with IFN-alpha or IFN-gamma and the change in their fluorescence was monitored by flow cytometry. NK activity after treatment with IFN-alpha or -gamma was also monitored in parallel using a standard 51Cr-release assay. IFN-alpha treatment of PBMCs caused an apparent depolarisation and subsequent hyperpolarization of the cell membranes. Such changes reflect movement of ions across the cell membrane and also the binding of IFN-alpha to the cell surface receptor. Molecular conformational changes in the cell membrane due to IFN-alpha and IFN-gamma were monitored by labelling cell populations with NPN. Changes in NPN-labelled cell fluorescence intensity, indicating changes in membrane conformation, were greatest in NK cell populations activated by IFN-gamma. IFN-alpha had a more profound effect on non-NK cell populations. The concentration of free intracellular Ca2+ ions is also affected by IFN-alpha and IFN-gamma activation, as monitored by the fluorescent probe, Quin 2. There is an apparent decrease in intracellular Ca2+ ion concentration in the NK cell population when treated with IFNs, with the greatest effect being shown by IFN-gamma. These data indicate that the effects of IFNs on NK cells can be monitored at a cellular level using fluorescent probes and flow cytometry. As analysed by these probes, IFN-alpha and IFN-gamma appear to affect NK cells via different mechanisms.

1-Naphthylamine↗
PubMed1988

Growth of rat osteoblast-like cells in a lipid-enriched culture medium and regulation of function by parathyroid hormone and 1,25-dihydroxyvitamin D.

To examine the role of lipid metabolism in the growth and function of osteoblast-like cells, we studied ROS 17/2.8 osteosarcoma cells and primary cultures of rat calvarial osteoblasts during growth in a serum-free medium supplemented by purified human lipoproteins or by liposomes. Increase in ROS cell number was measured in sparse (1-5 X 10(3)/cm2) cultures over 6-8 days. Liposomes (0-300 micrograms/ml) and high (HDL), low (LDL), and very low density (VLDL) lipoprotein fractions (0-300 micrograms apoprotein) markedly stimulated cell growth. Cells plated at 5 X 10(3)/cm2 achieved growth rates in the presence of LDL or HDL comparable to 10% fetal bovine serum. Serum-free culture with exogenous lipid maintained the response of cell cyclic AMP accumulation to parathyroid hormone. Cyclic AMP response to parathyroid hormone was enhanced by glucocorticosteroid, and was attenuated by 1,25-dihydroxyvitamin D (1,25(OH)2D) with an EC50 (10(-10) M) comparable to that previously observed in serum-cultured cells (J. Biol. Chem. 258:736, 1985). 1,25(OH)2D also increased the alkaline phosphatase activity in ROS cells cultured in lipid-supplemented serum-free culture. Lipoproteins or liposomes also markedly enhanced the proliferative response of sparse cultures of normal rat osteoblasts to polypeptide mitogens.

Animals↗
PubMed1987

Evidence of hepatitis virus infection among Australian prisoners of war during World War II.

A sample of Australian male veterans of World War II was surveyed after 40 years. One hundred and seventy veterans had been held by the Japanese as prisoners of war and 172 veterans had served in southeast Asia but had not been taken captive (non-prisoners of war). A medical history was obtained and a physical examination undertaken. Blood was drawn and analysed for standard liver biochemistry and serological markers of hepatitis A and B virus (HAV, HBV) infections. The prevalence of immunoglobulin (Ig)G class antibodies to HAV was 95.2% in non-prisoners of war and 93.3% in prisoners of war. Only three cases of hepatitis B surface antigen (HBsAg) seropositivity were identified (two cases from the prisoner-of-war group). Thirty-six (21.8%) prisoners of war were seropositive for the presence of antibodies to HBsAg (anti-HBs) and 34 (20.0%) prisoners of war for that of antibodies to hepatitis B core antigen (anti-HBc), compared with 16 (9.8%) and eight (4.7%) of the non-prisoners of war, respectively (P = 0.002 and P = 0.0001, respectively). Those veterans who reported jaundice during World War II had a higher prevalence of antibodies to HBV. Among prisoners of war who were forced to work on the Burma-Thailand railway, 24.1% were seropositive for anti-HBc compared with 11.1% of the remaining prisoners of war (P = 0.048). It would appear that hepatitis B was common in prisoners of war but that those who survived 40 years were able to clear the virus and do not appear to have significant liver disease.

Asia, Southeastern↗
PubMed1986

A fluorescence NK assay using flow cytometry.

A flow cytometric NK assay was developed in which the K562 targets were labelled with the fluorogenic substrate, carboxyfluorescein diacetate (c'FDA). This new assay compared favourably with results obtained using the conventional 51Cr-release assay. c'FDA was not toxic to target cells and did not inhibit lysis. The assay permits the evaluation of various aspects of NK activity such as the activity of NK-enriched, IFN-alpha-activated, and ALG-inhibited populations. The assay can be used in place of 51Cr-release, and has the advantages of being able to directly monitor target cell lysis of reducing overall assay time, and the avoidance of radioisotope usage.

Adult↗
PubMed1986

Female marrow donors increase the risk of acute graft-versus-host disease: effect of donor age and parity and analysis of cell subpopulations in the donor marrow inoculum.

We evaluated 27 factors for their influence on acute graft-versus-host disease (GVHD) in 40 recipients of HLA-identical sibling marrow transplants. These factors included the doses of mononuclear cell subpopulations present in the donor marrow inoculum quantitated using a panel of monoclonal antibodies. Female donors were associated with increased severity of acute GVHD, and the older the female donor the greater this effect. Increasing donor parity was also associated with an increased risk of acute GVHD. The number of T cells, T cells subsets, natural killer cells and monocytes infused did not influence the incidence or severity of acute GVHD in this study, and we could not explain the influence of female donors and of female donor age on acute GVHD by the cellular content of their marrow inocula. We postulate that non-HLA histocompatibility antigen disparity is a more important determinant for acute GVHD than the number of infused donor T cells, especially when female donors are used. The association between acute GVHD and increasing parity suggests that some female marrow donors have been pre-sensitized to their respective recipients by preceding pregnancies.

Acute Disease↗
PubMed1985

Gastrointestinal morbidity among World War II prisoners of war: 40 years on.

A study of Australian male World War II veterans was conducted to assess clinically the gastrointestinal ill-effects which were present 40 years after the stress of internment as prisoners of war of the Japanese. A random sample of 170 surviving members of the captured Eighth Army Division resident in Sydney in 1983 (ex-POW) was compared with a similar sample of veterans who fought in Southeast Asia during the War, but were not imprisoned (non-POW). Duodenal ulcers and strongyloidiasis were more prevalent in the ex-POW group than in the non-POW group. The increased rate of duodenal ulcer (24.7%, compared with 10.5%; P = 0.0005) was confirmed by a higher proportion of ex-POWs currently taking cimetidine (9.0%, compared with 2.3%; P = 0.008). Strongyloidiasis had been found in 9.7% of all veterans, but in 15% of ex-POWs and in 19% of those who had worked on the Burma-Thailand railway. No other significant differences in gastrointestinal disease were found.

Aged↗
PubMed1982

Evolution of fascioliasis after eating wild watercress.

Fascioliasis is rarely reported in humans although it is endemic in sheep and cattle. We describe the illness of a 60-year-old widow who ate wild watercress which is the usual source of infestation. Laparotomy for suspected liver abscesses revealed necrotic tracts on the surface of the liver left by the invasion of numerous flukes. Diagnosis was made during the latent phase by the detection of serum antibody to fasciola hepatica antigen obtained from a sheep. Symptoms returned during the cholestatic phase. Mature flukes were then present in the large bile ducts and ova appeared in the stools. Symptoms resolved twelve weeks after presentation.

Australia↗