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Biomedical subjects

A Simpson

Publications and source records attributed to A Simpson.

70 records · Page 4Linked to original sources

Gastrin related peptide effects in lateral hypothalamus depend on food deprivation.

Gastrin related peptides (PG) affected neurons in the lateral hypothalamus (LHA) differently in food deprived than in non-deprived rats. Electroosmosis and intravenous (IV) results agreed. Gastric acid secretion was also measured. Neural responses to PG were: transiently increased discharge rate followed by desensitization occurred equally in deprived and non-deprived rats; dose related decrease in discharge rate occurred significantly more often in non-deprived than in deprived rats. Observed LHA changes and gastric acid secretion occurred pari passu. It was concluded that PG could contribute to LHA control of feeding behavior. It was not determined whether the effects attributed to systemic injection and those attributed to electroosmotic application both had the same origin. The significant differences which were observed could have been either different reacttions by one neuron type, or responses of different neuron types.

Animals

The Jk(a-b-) phenotype in New Zealand Polynesians.

The Kidd locus phenotype Jk(a-b-) was detected in 0.9 percent of Polynesians living in New Zealand. Over a period of 13 years, nine examples of anti-Jk3 were detected, one of which caused a delayed hemolytic transfusion reaction. Other examples resulted in mild hemolytic disease of the newborn. The anti-Jk3 reacted as an inseparable antibody, confirmed that inheritance of the Jk(a-b-) phenotype was best explained by the presence of a silent Jk allele.

Alleles

Antitumor, antiviral and immunopotentiating activities of pine cone extracts: potential medicinal efficacy of natural and synthetic lignin-related materials (review).

Several antitumor substances that effectively inhibited the growth of ascites and solid tumor cells transplanted in mice were isolated from pine cone NaOH extract by acid- and ethanol-precipitation. These antitumor substances were also potent antiviral agents against human immunodeficiency virus, herpes simplex virus and influenza virus; they induced antimicrobial activity against Staphylococcal aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Candida albicans, and induced antiparasite activity against Hymenolepis nana in mice. Chemical analysis of these substances by IR, UV, NMR, ESR and partition chromatography on cellulose-TLC plate disclosed that they had lignin-related structures complexed with sugars or polysaccharides. Chlorinated decomposition of the lignin portion significantly reduced their antiviral activity. In agreement with this, the antiviral activity of synthesized lignins prepared by polymerization of phenylpropanoid precursors was comparable to that of the undecomposed counterparts of the pine cone extract. Acid hydrolysis of the polysaccharide portion significantly reduced the ability of the substances to induce antitumor and antimicrobial activities in mice. With an appropriate eliciting agent, intravenous administration of natural lignified substances transiently induced endogenous production of a cytotoxic factor (possibly tumor necrosis factor) in normal mice. Their priming activity was significantly higher than that of their component units or degradation products. These data suggest the importance of conjugating lignins with polysaccharides for in vivo expression of various kinds of immunopotentiating activity. As possible explanations for their induction of a variety of immunopotentiating activities, these natural and synthetic lignins stimulated macrophage NBT-reducing activity, polymorphonuclear cell (PMN) iodination and splenocyte DNA synthesis and inhibited poly (ADP-ribose) glycohydrolase, RNA-dependent DNA polymerase (reverse transcriptase) and RNA-dependent RNA polymerase activities.

Adjuvants, Immunologic

Induction of immunopotentiation activity by a protein-bound polysaccharide, PSK (review).

A protein-bound polysaccharide, PSK, extracted from the mycelium of Coriolus versicolor (Fr.) Quel, has been recognized for its host-mediated induction of antitumor and antimicrobial activities in mice. Intravenous administration of PSK, in association with OK-432 (Picibanil), transiently induced endogenous production of a cytotoxic factor (CF) (possibly tumor necrosis factor, TNF) in normal mice. The ability to produce CF depended greatly on both dose and interval between administration of the PSK and OK-432. Although PSK has been reported to contain several active ingredients, unfractionated PSK has been used in almost all experiments performed so far. We recently reported that, of the four subfractions separated by successive filtration through membrane filters, only the highest molecular weight fraction F4 (MW greater than 200 kD) induced significant antimicrobial activity in mice. PSK stimulated the NBT-reducing activity of mouse peritoneal macrophages and the iodination (incorporation of radioactive iodine into an acid-insoluble fraction) of human peripheral blood polymorphonuclear cells (PMN). Among the subfractions of PSK, the highest molecular weight fraction F4, and the fraction precipitated at pH 4.0-4.5 (Fr. 4), stimulated macrophage NBT-reducing activity and PMN iodination most. In contrast, natural and chemically modified glucans had little or no stimulating activity. PSK, F4 or Fr. 4 additively or synergistically stimulated TNF-induced cytotoxicity against L-929 cells, differentiation of human myelogenous leukemia cell lines toward monocytes/macrophages, and iodination of human peripheral blood PMN. The active PSK subfractions significantly reduced the down regulation of specific 125I-TNF or 125I-IFN-gamma binding to cellular receptors. These data suggest that (i) immunopotentiation activity of PSK might be ascribed, at least in part, to stimulation of cytokine action and production, and (ii) PSK might have some unique structural features.

Adjuvants, Immunologic