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Biomedical subjects

G Fink

Publications and source records attributed to G Fink.

At least 307 records · Page 17Linked to original sources
PubMed1973

Specific biologic effects of intestinal glucagon-like materials.

It has been demonstrated that gastrointestinal extracts contain substances which react immunologically with antibodies prepared to pancreatic glucagon. These extracts have been termed intestinal GLI for glucagon-like immunoreactivity, or enteroglucagon. To determine whether GLI has specific biological effects, studies were designed using the criterion of effect with antiglucagon antibodies. These antibodies did not cross-react with either secretin or pancreozymin. Rat intestinal extracts were prepared and filtered on Sephadex G-50 columns eluted in 0.02 M ammonium carbonate buffer pH 8.8. Two peaks of GLI (I, II) were consistently found, and the in vitro effects of these peaks on two biological systems were tested: (a) immunoreactive insulin (IRI) release by rat pancreas pieces, and (b) free fatty acid (FFA) release and 3',5'-cyclic adenosine monophosphate (cAMP) levels in adipose tissue. Both GLI peaks increased IRI release in the absence of glucose and also enhanced the glucose effects. Antiglucagon antibody suppressed only peak II GLI activity. Both peaks increased FFA release and cAMP levels in adipose tissue. Only peak II GLI activity was suppressed by antibody. These findings support a specific IRI-releasing and lipolytic action for Peak II GLI. Hypotheses are presented concerning the structure and possible physiologic role of peak II GLI.

Adipose Tissue↗
PubMed1970

The luteinizing hormone releasing activity of extracts of blood from the hypophysial portal vessels of rats.

1. A method of acid ethanol extraction and gel filtration was used to obtain a ;luteinizing hormone (LH)-free' fraction of blood collected from the cut pituitary stalk of rats (termed hypophysial portal blood).2. The ;LH-free' fraction of hypophysial portal plasma from hypophysectomized and from ovariectomized rats caused a greater depletion of ovarian ascorbic acid in immature rats, pretreated with gonadotrophins, than a similar fraction of systemic plasma obtained from the same donor animals.3. The ;LH-free' fraction of hypophysial portal plasma from ovariectomized rats evoked a rise in the level of LH in the systemic plasma of ovariectomized, oestrogen and progesterone treated, rats. This fraction also caused ovulation in rabbits when infused directly into the anterior pituitary gland of these animals. The activity of the ;LH-free' fraction of systemic plasma was considerably less than that of portal plasma in either of these assay systems.4. The results of these experiments suggest the presence of a factor in the ;LH-free' fraction of hypophysial portal plasma which is capable of causing the release of luteinizing hormone from the anterior pituitary gland. The molecular weight of this factor, as assessed by its behaviour on filtration through ;Sephadex G-25', is probably less than 5000.5. The LRF activity of the ;LH-free' fraction of hypophysial portal plasma obtained from rats at various phases of the oestrous cycle was measured by the ovarian ascorbic acid depletion method. There appears to be a decrease in the level of activity at oestrus. However, a rise in LRF activity, which was expected to occur at the ;critical period' of prooestrus, was not evident. The significance of these findings is discussed.

Animals↗