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Biomedical subjects

N Friedmann

Publications and source records attributed to N Friedmann.

At least 37 records · Page 2Linked to original sources
PubMed1976

Activation of protein kinase(s) by glucagon and cyclic AMP in the rat liver. Relationship to metabolic effects.

Although it is known that protein kinases are activated by cyclic AMP, the role of the activated kinase in the gluconeogenic response to cyclic AMP is not known. Therefore, we examined whether the inhibition of the gluconeogenic response in the liver is due to an interference with the activation of protein kinase in the following situations: (1) adrenalectomy, (2) Na+-free perfusate, (3) administration of local anesthetic. We measured protein kinase activity indirectly by measuring incorporation of 32P into proteins of the perfused liver, and directly by measuring the enzyme activity. We found no significant inhibition of activation of protein kinase in the above experimental conditions. It seems that in the intact liver, activation of protein kinase by itself is not sufficient to evoke metabolic responses. In order to clarify whether the requirement for ion redistribution is specific for the gluconeogenic response or not, the lipolytic and antilipogenic effects of glucagon and cyclic AMP were examined. Na+-free perfusate, local anesthetic or high K+ did interfere with the lipolytic and antilipogenic responses to these agents just as it interfered with the gluconeogenic response. It is likely that ion redistribution evoked by glucagon and cyclic AMP is essential to the expression of most, if not all, metabolic effects.

Adrenalectomy↗
PubMed1976

The effect of thymosin on human T-cells from cancer patients.

The effect of thymosin on in vitro reactivity of peripheral lymphocytes to phytohemagglutinin, concanavalin A, and the formation of spontaneous E-rosettes in 54 patients with metastatic carcinomas has been studied. Thymosin increased lymphocyte responses to PHA and Con A in only 10 patients, with predominant effect seen with Con A. Twenty patients showed depressed baseline levels of E-rosettes which were increased to normal or subnormal levels after incubation with thymosin. No distinct correlation was noted between the clinical stage of the disease and the ability of lymphocytes to form E-rosettes. Although the exact mechanism by which the thymus exerts its influence on host resistance is not clearly defined, present evidence supports the concept that the thymic hormone, thymosin, may be an important addition in treatment of cancer patients by increasing cell-mediated immunity.

Adolescent↗
PubMed1976

A fast in vitro effect of glucocorticoids on hepatic lipolysis.

A fast and direct effect of dexamethasone on liver metabolism is reported. In the perfused rat liver, addition of dexamethasone directly to the perfusate is followed by an increase in the level of free fatty acids (FFA) and glycerol. These effects of dexamethasone are evident within 30 minutes of hormone administration. The response to dexamethasone in livers from normal and adrenalectomized rats is similar. While dexamethasone and glucagon both had a lipolytic effect, these effects are not additive.

Adrenalectomy↗
PubMed1976

In vitro effect of thymosin on T cells from immunodepressed surgical patients.

In preparation for the use of bovine thymosin, a thymic hormone, as a specific T cell stimulator in immunodepressed patients, we studied its effect on E rosette formation of peripheral lymphocytes from patients with (1) advanced malignancies, (2) extensive burns, and (3) septicemia. E rosette formation in vitro with and without thymosin was evaluated in 52 patients with carcinoma of the breast (25) or lung (27) in relation to adjuvant therapy and/or surgery. The depression of E rosettes in cancer patients was most striking when adjuvant therapy, irradiation, and/or chemotherapy were used; in 20 patients this was elevated by incubation with thymosin. There was a delay in recovery of depressed E rosette levels after radical mastectomies in four patients, recovery being accelerated by thymosin. In ten burn patients (40 to 80 percent of body surface area, second and third degree burns), the depression in E rosette levels occurred in the first week and was most marked in 3 to 4 weeks. In eight patients this was elevated by thymosin in vitro. In four septic patients, all undergoing operation, serial studies suggested that recovery from sepsis was accompanied by spontaneous rise in E rosette levels. This process was accelerated by thymosin in vitro. This study as well as previous experiments with animals suggest that thymosin may influence depressed host resistance favorably by increasing T-cell-mediated immunity.

Adolescent↗
PubMed1972

Prebiotic synthesis of hydrophobic and protein amino acids.

The formation of amino acids by the action of electric discharges on a mixture of methane, nitrogen, and water with traces of ammonia was studied in detail. The presence of glycine, alanine, alpha-amino-n-butyric acid, alpha-aminoisobutyric acid, valine, norvaline, isovaline, leucine, isoleucine, alloisoleucine, norleucine, proline, aspartic acid, glutamic acid, serine, threonine, allothreonine, alpha-hydroxy-gamma-aminobutyric acid, and alpha,gamma-diaminobutyric acid was confirmed by ion-exchange chromatography and gas chromatography-mass spectrometry. All of the primary alpha-amino acids found in the Murchison Meteorite have been synthesized by this electric discharge experiment.

Alanine↗
PubMed1971

Primitive earth synthesis of nicotinic acid derivatives.

Nicotinonitrile, 2-cyanopyridine, and 4-cyanopyridine can be synthesized under primitive earth conditions by the action of electric discharges on ethylene and ammonia. The electric discharge first synthesizes pyridine and hydrogen cyanide, which react in the discharge to form the cyanopyridines. Nicotinonitrile would have hydrolyzed in the primitive ocean to nicotinamide and nicotinic acid.

Ammonia↗
PubMed1971

Cyclic adenosine and guaosine monophosphates and gucagon: effect on liver membrane potentials.

Cyclic adenosine monophosphate, cyclic guanosine monophosphate, glucagon, and isoproterenol each hyperpolarized perfused rat liver cells. The hyperpolarization followed a time course similar to the stimulated increase in potassium efflux and was preceded by the increase in calcium efflux. The hyperpolarization induced by cyclic adenosine monophosphate was blocked by tetracaine. The similarity of the action of the cyclic nucleotides to that of glucagon supports the hypothesis that cyclic adenosine monophosphate is the secondary messenger mediating the action of glucagon.

Adenine Nucleotides↗