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Biomedical subjects

R Landgraf

Publications and source records attributed to R Landgraf.

At least 325 records · Page 18Linked to original sources
PubMed1979

[Exocrine pancreatic secretion, gastrin and insulin in men by intraduodenal bolus injection of calcium (author's transl)].

The possible role of calcium in human bile during the biliary stimulated exocrine pancreatic secretion was investigated in 15 healthy volunteers. Total outputs of trypsin, bicarbonate, bilirubin and volume in the duodenal juice and serum gastrin were measured during a continuous intravenous infusion of secretion (0.5 CHR U/kg/h) for 40 min. The same parameters were determined after a single intraduodenal dose of Ca++ (20 ml 13,5, 135 or 270 mval/l, n = 5 for each dose) and compared with aequivalent intraduodenal dose of Na+ and an intravenous dose of secretion/cholecystokinin (1 CHR and IDU U/kg). Low calcium (13,5 mval/l) had no effect on the output of pancreatic enzymes and bile. However the higher doses led to a significant increases of the outputs of trypsin and bilirubin, which was about 75% of the enhancement seen with secretin/cholecystokinin in the dose used. Serumgastrin secretion was significantly increased only after the higher calcium doses.--Serum insulin in peripheral venous blood venous blood was unchanged after duodenal application of 20 ml 270 mval/l calcium (n = 5). From these data one has to conclude that the Ca++-content of bile has no stimulatory effect on the exocrine pancreas and on serum gastrin and insulin.

Adolescent↗
PubMed1979

Indications for a brain uptake of labelled vasopressin and ocytocin and the problem of the blood-brain barrier.

Fifteen seconds after intracarotid injection of [125J]-lysine vasopressin, [3H]-ocytocin, tritiated water or [3H]-inulin, the distribution of radioactivity in 18 regions of the rat brain and in the anterior pituitary was determined. Comparing the concentration of the different tracers (in % of injected radioactivity per g brain tissue), it is assumed that a small amount of the labelled neurohormones is taken up by the brain, indicating a penetration of the blood-brain barrier and/or an accumulation within the structures of the barrier system.

Animals↗
PubMed1978

[Clinical aspects, diagnosis and treatment of organic hyperinsulinism. Experience with 46 operated patients (author's transl)].

The clinical picture of organic hyperinsulinism is presented with reference to experience in 46 operated patients. For the recognition of disease, a careful history is a decisive contribution. The hunger test showed a characteristic hypoglycemic reaction in 100%; the tolbutamide test gave a positive result in 92%. Insulinomas could be localized angiographically in 71%; in one patient this could only be done with an ERCT. The treatment of choice is operation as soon as possible. If possible, enucleation is to be given preference over pancreas resection because of the low complication rate. A search for ectopic (2%) and multiple (12%) adenomas is important. A cure was achieved in 76% of all those operated on. The hospital mortality was about 4%.

Adenoma↗
PubMed1978

Sulphydryl requirement for insulin release from the perfused pancreas. Studies with ethacrynic acid and dithiothreitol.

Using the isolated, perfused rat pancreas the importance of sulphydryl groups for the secretory process of insulin was investigated. It was found that ethacrynic acid (EA, 0.075-0.6 mmol/1) caused a dose-dependent, monophasic insulin release. Addition of EA to a glucose-stimulated (20 mmol/1) pancreas led to a sudden increase in hormone release, followed by a dose-dependent inhibition of release, which was not reversible after removal of EA. The same phenomenon was seen in the presence of 20 mmol/1 leucine. Dithiothreitol (DTT, 0.1 and 1 mmol/1) had no effect on basal insulin secretion. Added to a glucose-stimulated pancreas DTT (1 mmol/1) caused a reversible inhibition of insulin release. The persistent inhibitory action of EA on glucose-induced insulin release could be reversed by simultaneous perfusion of EA and DTT. Sequential exposure of a glucose-stimulated pancreas to EA and DTT led to a rapid release of insulin, due to DTT; however, the EA-induced inhibition of insulin secretion could not be prevented. Two kinds of thiol groups in the plasma membrane and in the beta cell might be responsible for the various kinetics of insulin release induced by EA and DTT.

Animals↗
PubMed1978

Treatment of patients with prolactinomas.

Fifty-one female patients with prolactin producing tumors (PRL 1100 to 88,000 microU/ml) and 26 male patients with prolactin producing tumors (PRL 6500 to 400,000 microU/ml) were studied. Only 25% of the females had visual field defects which were present in 70% of the males. All females had amenorrhea but only 35 had galactorrhea. Hypopituitarism was rarely seen in the females but in most of the male patients. Twenty-four females and all male patients were operated (transphenoidal or transfrontal operation). PRL normalized in only eight females and in none of the males. Two patients became pregnant postoperatively, four after postoperative treatment with bromocriptine. Bromocriptine induced regular menses in 4 other patients operated by transsphenoidal route. Eight patients with microadenoma (PRL less than 4000 microU/ml) were treated with bromocriptine alone of whom two became pregnant. The males were also treated with bromocriptine leading to a significant fall of the PRL level accompanied by improvement of libido, sexual potency and headache. Two patients received radiation postoperatively, which led to a fall of PRL and improvement of visual fields. Since PRL levels remained low after withdrawal of bromocriptine for several months an antiproliferative effect of this drug is suggested. Thus differential therapy of PRL producing tumors is possible: In females selective neurosurgery can alone or combined with medical therapy normalize PRL secretion and ovarian function. In patients with microadenoma bromocriptine alone can be successful. In patients with inoperable large tumors radiation should be advocated. Additional bromocriptine therapy may be helpful to stop tumor growth and alleviate the effects of hyperprolactinemia.

Adenoma↗
PubMed1978

Regional net uptake of 14C-glucose by rat brain under the influence of corticosterone.

Fifteen seconds after intracarotid injection of either 14C-glucose or tritiated water in adrenalectomized rats, the net uptake of the respective tracer by 18 brain regions and by the anterior pituitary was measured. Corticosterone added to the injection solution (1 or 100 micrograms ml-1; 0.2 ml per animal) caused a dose-dependent decrease of net uptake of 14C-glucose in twelve regions. Compared to the net uptake of tritiated water which was used as a measure of relative blood flow, it suggests that this effect, at least partially, is due to a decreased blood-brain barrier permeability to 14C-glucose. Furthermore, the regional net uptake of 14C-glucose was estimated in rats with different endogenous corticosterone levels but injected with an identical solution in each case. Statistically significant differences could be observed between adrenalectomized and restrained animals in three brain regions.

Adrenalectomy↗
PubMed1978

The influence of vasopressin on the regional uptake of [3H] orotic acid by rat brain.

After intracarotid injection in the rat followed by decapitation 15 s later, the uptake of the RNA precursor [3H] orotic acid by 18 brain region and by the anterior pituitary was measured. Simultaneously injected lysine-8-vasopressin (1, 10, 100, 1000 and 10000 muU per ml injection solution, respectively) caused a dose-dependent enhancement of tracer uptake by 7 regions, e.g. by the hippocampus. There are indications that especially in this region the blood-brain barrier permeability to the precursor was influenced by the peptide hormone.

Animals↗
PubMed1977

Prolactin: a diabetogenic hormone.

During an oral glucose tolerance test (OGTT) glucose and insulin levels were measured in 26 patients with prolactin-producing pituitary tumours without growth hormone excess. Basal glucose and insulin levels did not differ from the values of an age-matched control group. After glucose load the hyperprolactinaemic patients showed a decrease in glucose tolerance and a hyperinsulinaemia. Bromocriptine (CB 154), which suppressed PRL, improved glucose tolerance and decreased insulin towards normal in second OGTT. Human PRL or CB 154 had no significant influence on insulin release due to glucose in the perfused rat pancreas. These findings suggest a diabetogenic effect of PRL. CB 154 might be a useful drug in improving glucose utilization in hormone-active pituitary tumours.

Adenoma↗
PubMed1977

[Effect of oxytocin on regional 3H-orotic acid uptake in rat brain].

The uptake of the RNA precursor [3H] orotic acid by 18 brain regions of male rats was measured after intracarotid injection and a survival time of 15 s. Ocytocin added to the injected solutions (final concentrations: 1 to 1000 mU/ml) caused a dose-dependent enhancement of tracer uptake by 11 areas. Some of these regions (e.g. hippocampus) are thought to be involved in the behavioral effects of vasopressin and other peptide hormones (Van Wimersma Greidanus et al., 1975 a). Results of experiments in which the net uptake of tritiated water was used as a measure of relative blood flow led us to the conclusion that the blood-brain barrier permeability to [3H] orotic acid rather than the cerebral blood flow is changed by ocytocin. The present results support the assumption that the enhanced precursor supply caused by ocytocin might contribute to the influence of this peptide hormone on memory consolidation.

Animals↗
PubMed1976

[Intraoperative vital staining of insulinoma using toluidine blue-o].

A case is reported in which in vivo staining of insuloma cells was performed intraoperatively, using Toluidine Blue-O. The surgical problems of islet-cell tumors are discussed with special regard to the indication of in vivo staining as a definite method of intraoperative identification of these tumors.

Adenoma, Islet Cell↗
PubMed1975

[Influence of somatastatin on oral glucose tolerance in autonomous hypersecretion of growth hormone, prolactin or insulin (author's transl)].

Oral glucose tolerance tests (OGTT) were performed for two subsequent days in 4 patients with active acromegaly, 2 patients with prolactin-producing pituitary adenomas and one insulinoma patient. Thirty minutes before the second OGTT 250 mug of somatostatin were injected intravenously as a bolus followed by a somatostatin infusion (500 mug) over 21/2 hours. The OGTTs were pathologic due to the hGH- and hPRL-induced insulin antagonism; they could not be normalized or improved by somatostatin. Only the peak of the blood sugar curve was shifted from one to two and a half hours after glucose administration; insulin and hGH levels were regularly suppressed after somatostatin whereas hPRL remained unchanged in most instances. Gastrin levels increased in all patients during the OGTT, the increase was suppressed in 4 patients. These findings show that the pathologic glucose tolerance due to insulin antagonism could not be improved by somatostatin in contrast to the deteriorated glucose tolerance in insulinopenic states.

Acromegaly↗