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Biomedical subjects

M J Schmidt

Publications and source records attributed to M J Schmidt.

At least 55 records · Page 3Linked to original sources
PubMed1979

Serum concentrations of oestradiol and progesterone during the normal oestrous cycle and early pregnancy in the lion (Panthera leo).

During a 6-month study period weekly serum samples demonstrated 9 oestradiol surges above 14 pg/ml (range 19-108 pg/ml) among 3 lionesses isolated from male lions. Intervals between peaks ranged from 3 to 8 weeks. Progesterone surges of more than 17 ng/ml (range 17-282 ng/ml) and lasting for 2-6 weeks were recorded after 7 of the oestradiol peaks. Sexual behaviour correlated well with the oestradiol peaks. Except for cornification following oestradiol peaks, there was no obvious vaginal cytology pattern at other times of the cycle. Pregnancy occurred after a 12-h contact with a male during behavioural oestrus. During gestation (108 days) oestradiol values remained low, while progesterone was elevated to 49 ng/ml within 12 h after mating, reaching a peak of 143 ng/ml at the 4th week, and remaining elevated during the next 2 months.

Animals↗
PubMed1978

Effect of lin-benzoadenosine and lin-benzoadenosine 3':5'-monophosphate on cyclic AMP-dependent protein kinase activity in vitro.

We have shown that the fluorescent "stretched-out" analog of cyclic AMP, namely linear-benzo-cyclic AMP, maximally activates brain protein kinase and protein kinase from skeletal muscle. The corresponding linear-benzoadenosine inhibits kinase activity slightly less than does adenosine. Thus, the 2.4A-wider versions of cyclic AMP and of adenosine interact with protein kinase in a manner similar to that of the natural compounds.

Adenosine↗
PubMed1977

Norepinephrine-stimulated cyclic AMP accumulation in brain slices in vitro after serotonin depletion or chronic administration of selective amine reuptake inhibitors.

These experiments demonstrate that altering serotonin availability in vivo does not influence the interaction of norepinephrine with adenylate cyclase in vitro. Neither reducing serotonin levels (parachloroamphetamine) nor increasing the availability of serotonin by blocking its reuptake (fluoxetine) affect the norepinephrine-induced elevation of cyclic AMP in slices of the limbic forebrain of rats. However, increasing norepinephrine availability by chronic administration of desipramine, a norepinephrine reuptake inhibitor, reduces cyclic AMP synthesis in the limbic forebrain. However, it is doubtful that blockade of norepinephrine reuptake alone accounts for the reduction in receptor sensitivity produced by desipramine since chronic administration of a new norepinephrine reuptake inhibitor, nisoxetine, does not decrease cyclic AMP accumulation.

Animals↗
PubMed1976

Effects of kainic acid, a cyclic analogue of glutamic acid, on cyclic nucleotide accumulation in slices of rat cerebellum.

The concentration of cyclic AMP (cAMP) and cyclic GMP (cGMP) in slices of rat cerebellum was increased markedly in the presence of 100 muM kainic acid, a cyclic analogue of glutamic acid. No acitvity was detected in other brain areas at various dosed or incubation times. Ksainic acid was significantly more potent than glutamic acid and other glutamate-like compounds. The increases in cAMP and cGMP could be differentially inhibited with theophylline or cocaine respectively, but both systems required calcium. Compounds similar in structure to kainic acid or glutamate did not block the effects of kainic acid.

Animals↗