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Biomedical subjects

R George

Publications and source records attributed to R George.

At least 145 records · Page 8Linked to original sources
PubMed1989

Multiply beta-lactam resistant Enterobacter cloacae infections linked to the environmental flora in a unit for cardiothoracic and vascular surgery.

During the period March 1987-May 1988, postoperative infection or colonization with Enterobacter cloacae occurred in 9/379 (2.4%) patients who underwent cardiovascular surgery. Five of the patients were infected with multiply beta-lactam resistant E. cloacae, of whom 4 had been infected with an identical, resistant strain during intervals of months. This strain was also found in the environmental flora of the cardiovascular operating suite and in a sink reservoir in the surgery department. All 4 patients with the identical resistant strain had serious complications during the postoperative period with symptoms of septicaemia in 3, multiorgan failure and shock in 2, and mediastinitis in 3. The single resistant strain of a different serotype was also associated with severe postoperative complications. The 4 sensitive strains were all different serotypes. None caused septicaemia, one was associated with mediastinitis, another with an uncomplicated sternum infection, and 2 were from sputum. In the 3 latter patients with sensitive strains and few postoperative complications, cephalosporins had not been used during the pre- or postoperative period.

Adult↗
PubMed1989

Characterization of the effects of the acute and chronic administration of phencyclidine on body temperature in the rat: lack of evidence for the involvement of opiate receptors.

The present study characterized the effects of the acute and chronic administration of phencyclidine on body temperature in the rat. The acute administration of phencyclidine produced hypothermia. This hypothermia occurred only after high doses of drug. In contrast, only hyperthermia was found in chronically treated subjects. The hyperthermia in chronically treated subjects was produced by low doses of drug, and sensitization to the hyperthermic effects took place over time. There was no evidence for the involvement of opiate receptors in the acute hypothermic response to phencyclidine, as the hypothermia was not antagonized by naloxone or decreased in chronically morphine-treated subjects. Moreover, the hypothermic response was enhanced by treatment with opiate receptor-active and -inactive enantiomers of naloxone, as well as in chronically morphine-treated subjects.

Animals↗
PubMed1989

Characterization of the effects of the acute and chronic administration of phencyclidine on the release of adrenocorticotropin, corticosterone and prolactin in the rat: evidence for the differential development of tolerance.

Phencyclidine (PCP) is a widely used drug of abuse; however, little is known of its effects on neuroendocrine function. The present study characterized the effects of the acute and chronic administration of PCP on the release of adrenocorticotropin, corticosterone and prolactin in the rat. For the acute studies, PCP hydrochloride (0.5-10.0 mg/kg s.c.) was administered and the subjects were sacrificed 15 to 300 min later. The acute administration of PCP produced rapid and long-lasting increases in plasma levels of adrenocorticotropin and corticosterone but decreased plasma levels of prolactin. For the chronic studies, PCP (1.0-20.0 mg/kg/day s.c.) was injected daily and the subjects sacrificed 60 min after injection on day 15. PCP continued to stimulate the pituitary-adrenal axis after chronic administration; however, there was a decrease in the magnitude of response, indicating the development of some degree of tolerance. In contrast, none of the doses of PCP tested decreased plasma prolactin levels in chronically treated subjects. There were no differences in plasma or brain levels of PCP in the chronically PCP-treated rats, indicating that tolerance was not due to changes in the biodisposition of PCP. These results indicate that PCP disrupts neuroendocrine function markedly in the rat. The differential development of tolerance to the effects of PCP on the pituitary-adrenal axis and prolactin release may indicate that different neurochemical substrates underlie the effects of PCP on different endocrine systems.

Adrenocorticotropic Hormone↗
PubMed1989

Child abuse and neglect as seen in General Hospital, Kuala Lumpur--a two year study.

Eighty-six children diagnosed as child abuse and/or neglect were admitted to the Paediatric wards of the General Hospital, Kuala Lumpur during 1985 and 1986. Of these cases, 62 were of physical abuse, six of sexual abuse, one case of both physical and sexual abuse and 17 of neglect. There were 25 boys and 61 girls. Thirty-four of these children were Malays, 16 Chinese, 26 Indians, three mixed and seven illegal immigrants. Twenty-one were below the age of one year, 24 from one to four years, 25 from five to nine years and 16 were ten years and above. The abusers were mainly close members of the family. Of these children, 24 were sent back to their parents and 11 to their relatives home. Twenty-seven were taken into care by the Ministry of Social Welfare and the remaining seven children who were illegal immigrants, were deported with their parents. Only one child was successfully fostered. Eleven children were taken away from the hospital by their parents or guardians without the knowledge of the health staff. There were five deaths in the series.

Child↗
PubMed1989

AIDS care team.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Solubilization and characterization of the chicken oocyte vitellogenin receptor.

This paper describes the biochemical characterization of the chicken oocyte plasma-membrane receptor for one of the major lipid-carrying yolk proteins, vitellogenin (VTG). The receptor was extracted from oocyte membranes with the non-ionic detergent octyl-beta-D-glucoside and visualized by ligand blotting, with 125I-VTG as a protein with an apparent Mr of 96000, under non-reducing conditions. It exhibited high affinity for native chicken VTG (Kd 2 X 10(-7) M) but was unable to bind VTG with reductively methylated lysine residues or phosvitin (the phosphoserine-rich intracellular cleavage product of VTG). Polyclonal antibodies to the 96 kDa protein inhibited VTG binding to the receptor and were able to precipitate functional VTG-receptor activity from oocyte-membrane detergent extracts with a concomitant removal of the 96 kDa protein. Antibodies directed against the mammalian receptor for low-density lipoprotein showed cross-reactivity with the chicken oocyte VTG receptor, raising the possibility that lipoprotein receptors in birds are structurally related to those in mammalian species.

Animals↗
PubMed1988

Characterization of sodium transport in Acholeplasma laidlawii B cells and in lipid vesicles containing purified A. laidlawii (Na+-Mg2+)-ATPase by using nuclear magnetic resonance spectroscopy and 22Na tracer techniques.

The active transport of sodium ions in live Acholeplasma laidlawii B cells and in lipid vesicles containing the (Na+-Mg2+)-ATPase from the plasma membrane of this microorganism was studied by 23Na nuclear magnetic resonance spectroscopic and 22Na tracer techniques, respectively. In live A. laidlawii B cells, the transport of sodium was an active process in which metabolic energy was harnessed for the extrusion of sodium ions against a concentration gradient. The process was inhibited by low temperatures and by the formation of gel state lipid in the plasma membrane of this organism. In reconstituted proteoliposomes containing the purified (Na+-Mg2+)-ATPase, the hydrolysis of ATP was accompanied by the transport of sodium ions into the lipid vesicles, and the transport process was impaired by reagents known to inhibit ATPase activity. At the normal growth temperature (37 degrees C), this transport process required a maximum of 1 mol of ATP per mol of sodium ion transported. Together, these results provide direct experimental evidence that the (Na+-Mg2+)-ATPase of the Acholeplasma laidlawii B membrane is the cation pump which maintains the low levels of intracellular sodium characteristic of this microorganism.

Acholeplasma laidlawii↗
PubMed1988

Unusual clinical manifestations of dengue virus infection.

Four recent cases of dengue fever with severe, unusual clinical manifestations are described. Two of these cases had features of fulminant hepatitis and encephalopathy; one of these cases was fatal. The two remaining cases showed hepatitis with renal impairment. The significance and importance of these unusual manifestations of dengue disease are discussed.

Adolescent↗
PubMed1988

Apolipoprotein specificity of the chicken oocyte receptor for low and very low density lipoproteins: lack of recognition of apolipoprotein VLDL-II.

At onset of egg-laying in the chicken, plasma levels of apolipoprotein VLDL-II (apoII) increase dramatically, suggesting a function of apoII in yolk deposition of triglyceride-rich lipoproteins. Thus, the possibility that this female-specific homodimeric protein (Mr of subunit, 9500) is recognized by the oocyte receptor for low and very low density lipoproteins was investigated. ApoII was purified from very low density lipoproteins by a novel, rapid procedure and reconstituted with egg phosphatidylcholine (PC) by detergent-dialysis. The resulting discoidal apoII/PC lipoprotein particles contained 3 mg of apoII per mg of PC and had a buoyant density of 1.062 g/ml. The ability of apoII/PC, as well as of physiological particles containing apoII but devoid of apolipoprotein B (apoB), namely high density lipoproteins (HDL) from laying hens, to interact with the oocyte receptor was tested. Both of these ligands failed to show saturable high affinity binding, in contrast to the apoB-containing ligands, low and very low density lipoproteins. Furthermore, neither laying-hen HDL which contain apoII and apoA-I nor apoII/PC were able to displace receptor-bound apoB-containing lipoproteins, as shown in competitive binding assays as well as by ligand blotting. Thus, we conclude that apoB, but not apoII, participates in binding and uptake of very low density lipoproteins via receptor-mediated endocytosis by growing chicken oocytes.

Animals↗
PubMed1987

Characterization of the chicken oocyte receptor for low and very low density lipoproteins.

The chicken oocyte receptor for low and very low density lipoproteins has been identified and characterized. Receptor activity present in octyl-beta-D-glucoside extracts of oocyte membranes was measured by a solid phase filtration assay, and the receptor was visualized by ligand blotting. The protein had an apparent Mr of 95,000 in sodium dodecyl sulfate-polyacrylamide gels under nonreducing conditions and exhibited high affinity for apolipoprotein B-containing lipoproteins, but not for high density lipoproteins or lipoproteins in which lysine residues had been reductively methylated. Binding of lipoproteins was sensitive to EDTA, suramin, and treatment with Pronase. In these aspects, the avian oocyte system was analogous to the mammalian low density lipoprotein receptor in somatic cells. Furthermore, a structural relationship between the mammalian and avian receptors was revealed by immunoblotting: polyclonal antibodies directed against the purified bovine low density lipoprotein receptor reacted selectively with the 95-kDa chicken receptor present in crude oocyte membrane extracts.

Animals↗
PubMed1987

Reconstitution of the purified (Na+ + Mg2+)-ATPase from Acholeplasma laidlawii B membranes into lipid vesicles and a characterization of the resulting proteoliposomes.

The purified (Na+ + Mg2+)-ATPase from Acholeplasma laidlawii B membranes was reconstituted with dimyristoylphosphatidylcholine using a cholate solubilization and dialysis procedure. The incorporation of this enzyme into the phospholipid bilayer is accompanied by an enhancement of its specific activity and by a restoration of its lipid phase state-dependent properties which were lost during solubilization and purification from native membranes. Moreover, reconstitution of this ATPase with phospholipid also stabilizes it against cold inactivation at low temperatures (approximately equal to 0 degrees C), oxidative degradation at room temperature, and thermal denaturation at elevated temperatures (approximately equal to 55 degrees C). The elution profile from a Sepharose 4B-CL column indicates that all of the ATPase protein is associated with the phospholipid vesicles and that the Stoke's radius of the proteoliposomes formed is smaller than that of the lipid vesicles formed in the absence of any protein. The latter conclusion is supported by sedimentation velocity measurements and by an electron microscopic examination of negatively stained preparations. The electron microscopic studies demonstrate that sealed vesicles are formed only at low protein-to-lipid ratios. These observations indicate that the Acholeplasma laidlawii B (Na+ + Mg2+)-ATPase has been structurally and functionally reconstituted into lipid vesicles and that the proteoliposomes formed are amenable to studies aimed at the clarification of its proposed role as a sodium ion pump.

Acholeplasma laidlawii↗
PubMed1987

The effects of the systemic administration of N-methylmorphine chloride, a quaternary analogue of morphine that does not cross the blood-brain barrier, on the release of anterior pituitary hormones in the rat.

The acute administration of morphine elicits changes in the release of anterior pituitary hormones. The locus of this action is thought to be in the central nervous system, specifically the hypothalamus. There are some data suggesting that systemically administered opiates and opioid peptides can act outside of the blood-brain barrier to influence anterior pituitary hormone release. To test this hypothesis we examined the effects of the systemic administration of N-methylmorphine chloride, a quaternary analogue of morphine that does not cross the blood-brain barrier, on the release of corticosterone, growth hormone, prolactin, luteinizing hormone, and thyroid stimulating hormone in the rat. N-methylmorphine caused increases in the release of growth hormone and prolactin, but serum levels of corticosterone, luteinizing hormone and thyroid stimulating hormone were unaffected. These results indicate that the opiate-induced release of growth hormone and prolactin may be mediated in part by sites outside of the blood-brain barrier.

Adrenocorticotropic Hormone↗