Correlation of immunogenicity with suppression of lymphocyte adenosine 3',5'-monophosphate-dependent protein kinase.

Cyclic-AMP-dependent protein kinase activity was depressed in whole spleen as well as in isolated splenic lymphocytes from 3-methylcholanthrene (MCA), R3230 AdCa mammary adenocarcinoma, N-hydroxy-2-acetylaminofluorene, and 4-dimethylaminoazobenzene (DMAAB) tumor-bearing Fischer rats as compared to control animals. The magnitude of depression increased with the immunogenicity of the tumor. The depressed enzyme activity was the result of a reduced Vmax for adenosine 3',5'-monophosphate (cAMP)-stimulated histone phosphorylation.     

Plasma cyclic 3',5'-guanosine monophosphate and cyclic 3',5'-adenosine monophosphate response to methacholine in man

Cholinergic agents are known to induce increases in tissue and plasma levels of cyclic GMP in experimental animals. We observed that i.m. injection of methacholine, a cholinergic agent, caused significant increases in plasma cyclic GMP and cyclic AMP in man.     

The response of cyclic 3',5'-AMP and cyclic 3',5'-GMP phosphodiesterases to experimental diabetes

Alloxan diabetes caused a decrease in cyclic AMP phosphodiesterase in all affected rat tissues. Cyclic GMP phosphodiesterase activity was, however, decreased in adipose and liver, but increased increased in heart and uterus.     

Interaction between dehydroepiandrosterone, glucose-6-phosphate dehydrogenase, and cyclic adenosine-3',5'-monophosphate in neoplastic and normal human mammary tissue.

When total DHEA, G-6-PDH activity, and c-AMP were determined in human neoplastic mammary tissue and corresponding normal tissue the G-6-PDH activity in the former tissue greatly exceeded that found in normal tissue. On the other hand, a remarkable decrease of total DHEA and c-AMP could be detected in cancer tissue, hinting at the participation of DHEA in the intracellular regulation of G-6-PDH and c-AMP levels.     

Correlation between brain blood flow and catecholamine levels in rat brain areas under hypobaric hypoxia

Summary Hypobaric hypoxia induces an important increase in the cerebral blood flow in all areas and more particularly in the bulb and hypothalamus; the increase in the cerebral blood flow allows for an oxygen intake sufficient to maintain the norepinephrine level in these structures.     

Effects of morphine administration on cerebellar guanosine 3',5'-monophosphate.

An increase in mouse cerebellar C-GMP levels during acute morphine treatment was observed, which was possibly related to the decrease in C-GMP phosphodiesterase levels also observed in acute treatment. Chronic treatment lowered C-GMP levels as did abrupt withdrawal without naloxone.     

Adenosine promoted accumulation of adenosine 3',5'-monophosphate in rabbit vagus nerve.

Desheathed rabbit vagus nerve has been found to form cyclic AMP when incubated with adenosine. This accumulation of cyclic AMP is inhibited by theophylline but not by antiadrenergic agents, anticholinergic agents or local anaesthetics. Depolarizing media are not able to promote cyclic AMP accumulation in this preparation.     

Regional and strain variation in brain 3':5' cyclic adenosine monophosphate of inbred mice.

Regional variations were found in cAMP levels in flash frozen mouse brains with the pons and cerebellum having higher levels than the cerebrum. There were also strain variations with CBA/J and BALB/cJ having higher levels than C57B1/6J in the pons and cerebellum.     

Free and sulfoconjugated dehydroepiandrosterone, cyclic adenosime-3',5'-monophosphate, and free estriol in maternal and cord blood.

When free DHEA, its sulfatide, and sulfate were assayed in maternal plasma as well as in umbilical cord arterial and venous plasma, rather high concentrations were found in either fraction from cord arterial plasma, reflecting the fetal contribution not only of free DHEA and DHEA sulfate, but also of the lipophile steroid sulfatide. Since high DHEA levels were associated with elevated c-AMP concentrations, a certain interrelationship of both parameters is indicated. In the course of delivery, a rapid decrease of free estriol in maternal plasma was observed. Higher concentration of free estriol in umbilical venous plasma pointed at its placental biosynthesis from fetal precursors.     

Absence of effects of dibutyryl cyclic guanosine 3',5'-monophosphate on release of alpha-amylase, 45Ca efflux, and protein synthesis in rat pancreas in vitro.

Dibutyryl cyclic GMP did not affect basal, or carbachol stimulated secretion of alpha-amylase from rat pancreas. The nucleotide did not have a significant effect on 45Ca release from the pancreas nor did it alter the response to carbachol. The dibutyryl analogue of cyclic GMP did not duplicate or alter the inhibitory effect of carbachol on 3H-leucine incorporation into pancreatic trichloroacetic acid-precipitable protein.