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Biomedical subjects

G Smith

Publications and source records attributed to G Smith.

At least 901 records · Page 50Linked to original sources
PubMed1976

Enhancement of a tumor allograft in BALB/c x DBA/2 F1 mice by pyran copolymer.

Pyran copolymer (NSC 46015) was evaluated with respect to its effect on the rejection of a murine leukemic allograft by BALB/c x DBA/2 F1 (CD2F1) mice. Significant prolongation of allograft survival with production of progressively growing lethal tumors was found following pyran administration. This phenomenon occurred at nontoxic doses of the drug and appeared to be closely related to the timing of pyran injection. Nonspecifically stimulated lymphocyte blast transformation by concanavalin A was not impaired by pyran when lymphocytes were exposed in vitro to the drug. The mechanism of tumor allograft enhancement remains obscure but may be related to allograft size at the time of pyran administration.

Animals↗
PubMed1976

Isolation of a new lipolytic-melanotropic peptide from human pituitary glands.

A new peptide having both lipolytic and melanotropic properties has been isolated from human pituitary glands. It has a molecular weight around 11,000, an amino acid composition different from the known lipolytic-melanotropic hormones, and an isoelectric point of 8.5. Although it is not entirely pure, there is no doubt that it differs from other known lipolytic-melanotropic substances in its total lack of methionine and tryptophan and its unusually high content of lysine and histidine. It has a melanocyte-stimulating hormone activity of 19 units/mug. As a lipolytic agent it is active with rabbit adipocytes, only slightly active with human cells and inactive with adipocytes from the rat.

Alanine↗
PubMed1975

The neurosecretory cells of the optic lobe in Carcinus maenas (L).

The six types of neurosecretory cell in the optic lobe of Carcinus maenas described by light microscopy are recognised by electron microscopy. They are categorised according to size, distribution of organelles and type of neurosecretory product. The neuro-secretory material,produced as granules by the Golgi bodies, migrates to the cell periphery eventually reaching the sinus gland via the neurosecretory cell axon extension. No change in size occurs in the granules but the density does alter. Each cell type has its own characteristic type of neurosecretory granule based on size and electron density. Multivesicular and lytic bodies in cell types 1,2,3,4 and 6 suggest a cycle for degrading neurosecretory material. Such a cycle is not so evident in cell type 5. Peripheral release of neurosecretory material is suggested for cell type 6 although the fate of the material is unknown.

Animals↗
PubMed1975

Inhibition of hepatic aryl hydrocarbon hydroxylase by 3-methylcholanthrene, 7,8-benzoflavone and other inducers added in vitro.

A close correlation has been observed between the ability of aromatic polycyclic hydrocarbons and 7,8-benzoflavone (7,8-BF) to induce hepatic aryl hydrocarbon hydroxylase (AHH) in vivo and to inhibit the induced enzyme system in vitro. The activity of this mono-oxygenase was measured by the conversion of 14C-labeled dimethylbenz(a)anthracene (DMBA) or benzo(a)pyrene (BP) to water-soluble products by rat liver preparations (8000 X g supernatant). DMBA as substrate had the advantage over BP in giving a wider range of ethyl acetate-soluble metabolites and allowing the observation of changes in the pattern of these products following injection or addition of the inducing agents. This property was used to detect low concentration (0.1 muM) of polycyclic hydrocarbons which are strong AHH inducers and which may also be carcinogenic. The liver preparation was active for several months when stored at --20 degrees. A possible mechanism of action for the in vitro behaviour of polycyclic hydrocarbons and 7,8-BF towards AHH is proposed.

Animals↗
PubMed1975

Metabolism of (4-14C)estradiol by 7,12-dimethylbenz(a) anthracene-induced mammary tumor peroxidase.

The peroxidase and estradiol-metabolizing activities of mammary tumors induced by 7,12-dimethylbenz(a)anthracene were determined in fresh and stored tissue. In both cases, a wide variation in peroxidase activity was observed in 47 different tumors tested. The properties of the enzyme found in the tumors were similar to those of lactoperoxidase. It is suggested that the amount of peroxidase present might reflect the ability of tumor cells to differentiate in response to hormonal stimulation and be indicative of the degree of tumor progression.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1975

Oxygen toxicity.

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Animals↗
PubMed1975

The combined effect of halothane-induced hypotension and hypocapnia on canine myocardial blood-flow and oxygen consumption.

In eleven intact mechanically ventilated dogs anaesthetized with pentobarbitone, mean arterial pressure was reduced to 55% of the control value by ventilating with 1-1.5% halothane. At normocapnia this resulted in decreases in myocardial blood-flow and oxygen consumption to 47% and 55% of their respective control values and an increase in myocardial vascular resistance to 123% of control value. When hypocapnia (mean PaCO2=26 mm Hg) was superimposed on hypotension, myocardial blood-flow was further decreased to 38% of control value whereas oxygen consumption did not alter significantly. When halothane was discontinued, allowing recovery from hypotension, the rate of recovery of myocardial blood-flow and cardiac output was much slower than that of arterial pressure.

Animals↗
PubMed1975

Effect of supplements of zinc salts on the healing of granulating wounds in the rat and guinea pig.

It has now been universally accepted that zinc deficiency interferes in some way with wound healing, but the claims that the addition of zinc supplements to the normally nourished rat accelerates wound healing to super-normal levels has, on investigations, produced contradictory results. In this study the rate of healing of granulating wounds on the backs of two species of animals, the rat and the guinea pig, has been studied when supplements of zinc salts were given in association with a normal diet. The zinc supplements were administered either orally, parenterally, or topically. There was no difference in the rate of healing in either species of animal given zinc supplements by any of the routes used.

Administration, Oral↗
PubMed1975

Effect of supplements of zinc salts on the healing of incised wounds in the rat and guinea pig.

Zinc deficiency affects healing as shown by measurement of two parameters of wound healing in the rat, namely the rate of healing of an excised, granulating wound and the development of tensile strength in an incised wound. The rate of healing of granulating wounds in two species of animals, the rat and the guinea pig, is not affected by the addition of supplements of zinc salts to the normal diet (J. Nutr. 105, 815-821). In this study, the development of tensile strength in incised wounds in rats and guinea pigs was measured at 7 and 14 days after wounding in animals given supplements of zinc salts by either the oral or parenteral route. No difference in tensile strength was observed at these times in the wounds of either rats or guinea pigs given zinc supplements.

Administration, Oral↗
PubMed1975

Uptake, activation, and esterification of fatty acids in the small intestine of suckling rat.

The small intestinal mucosal phase of fatty acid absorption was studied in suckling and adult rats. Fatty acid binding protein (FABP) is present in the cytosol of jejunal mucosa of 6-day-old rats in amounts equivalent to that found in mucosal cytosol of adult rats (16.4% and 15.0%, respectively). The percentage of oleic acid binding to FABP is the same in 6-day-old and adult rats (13.9% and 10.2%, respectively). The specific activity of jejunal microsomal oleoyl-CoA synthetase is high in the fetus, falls abruptly after birth, but increased by the third day of life to remain constant thereafter into adult life. In contrast the specific activity of acyl-CoA:monoglyceride acyltransferase is low in the fetal jejunum, gradually increases, and is significantly higher in the 6- and 12-day-old rat than in the adult. Uptake of oleic acid by jejunal slices of 6- and 11-day-old animals is three- to fivefold higher than uptake by jejunal slices prepared from adult rats. The rate of esterification of oleic acid is higher in jejunal slices from 6- and 11-day-old rats, reflecting the enhanced uptake of oleic acid.

Acyltransferases↗