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Biomedical subjects

R S Phillips

Publications and source records attributed to R S Phillips.

At least 235 records · Page 13Linked to original sources
PubMed1983

Dopamine-B-hydroxylase: suicide inhibition by the novel olefinic substrate, 1-phenyl-1-aminomethylethene.

Dopamine-B-hydroxylase [E.C.1.14.17.1] plays a key role in the biosynthetic interconversion of neurotransmitters. It is now demonstrated for the first time that dopamine-B-hydroxylase also catalyzes the oxygenation of an olefinic substrate, 1-phenyl-1-aminomethylethene, producing 2,3-dihydroxy-2-phenylpropylamine after acid workup. This reaction gives the normal oxygenase stoichiometry of electrons to O2 to product of 2:1:1, and is kinetically comparable to other oxygenase activities of dopamine-B-hydroxylase, with a kcat value of 10 sec-1 and a KM of 8.3 mM. 1-Phenyl-1-aminomethylethene is also a time-dependent, first-order inactivator of dopamine-B-hydroxylase. The inactivation process exhibits the characteristics of mechanism-based, irreversible inactivation, giving a KI value of 13 mM and a kinac of 0.04 min-1. The central role of dopamine-B-hydroxylase in catecholamine metabolism suggests possible pharmacological uses for olefinic inhibitors of this enzyme.

Adrenal Glands↗
PubMed1983

Suppression of primary and secondary antibody responses and inhibition of antigen priming during Babesia microti infections in mice.

The antibody response to sheep red blood cells (SRBC) has been measured in C57Bl mice infected with the intra-erythrocytic piroplasm Babesia microti. The primary antibody response is severely reduced or abolished when antigen is administered at the time of maximum parasitaemia. The secondary antibody response of infected mice, which had been primed with SRBC, is reduced but retains the characteristics of a secondary response. Mice injected with SRBC at maximum parasitaemia failed to become primed to that antigen: these mice gave a primary antibody response to a second injection of SRBC given after the infection had become sub-patent. B. microti, therefore, can completely prevent the induction of memory, but only partially inhibit the expression of memory.

Animals↗
PubMed1983

Induction of secondary antibody responses to Plasmodium chabaudi in vitro.

Spleen cells and peripheral blood mononuclear cells (PBMC) from mice, which had recovered from infection with Plasmodium chabaudi, were induced to produce anti-P. chabaudi antibody by incubating the cells with P. chabaudi parasitized red cells in Marbrook cultures. The anti-malarial antibody was assayed using the indirect fluorescent antibody test. Spleen cells and PBMC from mice infected 2-4 months previously gave higher antibody titres in culture than similar cells from mice infected a year previously. There was a good correlation between the ability of spleen cells or PBMC to be stimulated to produce antibody in vitro and the ability of mice similar to the cell donors to resist a challenge infection. Some immunity can be adoptively transferred with both spleen cells and PBMC.

Animals↗
PubMed1981

Use of sorbitol in the cryopreservation of babesia.

Blood collected from mice infected with Babesia microti was frozen at two different rates to -196 degrees C using 19 per cent (w/v) glycerol as cryoprotectant. Survival of the parasites was measured by recording the parasitaemias of mice inoculated with thawed blood. Parasite survival was increased by using a solution of sorbitol in saline rather than Hanks' balanced salt solution as the diluent for the glycerol and for washing the recovered blood.

Animals↗