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Biomedical subjects

R Landgraf

Publications and source records attributed to R Landgraf.

At least 253 records · Page 14Linked to original sources
PubMed1990

Hormonal and renal responses to arterial chemoreceptor stimulation by almitrine in healthy and normotensive men.

Healthy and normotensive men (n = 11) were hospitalized and kept under controlled fluid and sodium intake (120 mequ/d) for 5 days. Their systemic arterial blood pressures as well as heart and breathing rates were measured, and venous blood and urine samples were collected at intervals of 1-4 h. Diuresis was induced by scheduled drinking of tea (150 ml/h). Electrolytes, osmolality, and creatinine were determined in both plasma and urine samples. Aldosterone, cortisol, and vasopressin concentrations were measured only in the plasma. On the 2nd and 3rd day of the experiments the participants received orally either a placebo-pill or 100 mg almitrine bismesylate (Vectarion). Each subject was tested in a placebo- and an almitrine experiment. The subjects responded to the almitrine treatment with a suppression of the plasma aldosterone content, a transient rise of glomerular filtration rate, a natriuresis and an increase of renal concentrating ability. In the placebo-experiments, only the transient rise of filtration rate was significant. The data indicate that almitrine, by stimulating the peripheral arterial chemoreceptors, suppresses plasma aldosterone and inhibits renal proximal sodium reabsorption by so far unknown mechanisms. They also suggest that oral and intravenous almitrine administrations, respectively, might differently affect renal hemodynamics and excretory function.

Adult↗
PubMed1989

[Protracted blood sugar increase in type 1 diabetics after brief but exhausting muscular exercise].

In eight type I diabetics-three of them under intensified insulin therapy and five on continuous subcutaneous insulin infusion (CSII)-blood-glucose concentrations fell significantly during 20-minute isometric and dynamic muscle work at about 50% of individual maximal work capacity and subsequent intensive exercise of five minutes until exhaustion. However, 6 1/2 hours later blood-glucose levels (221 +/- 39 mg/dl after isometric exercise and 219 +/- 24 mg/dl after dynamic exercise) were clearly above the mean level measured at the same time of day on the three preceding days of 138 +/- 12 mg/dl (P less than 0.05). No hypoglycaemia occurred. This blood-sugar profile can be explained by a significant rise in cortisol and growth hormone and their long-lasting blood-sugar raising effect.

Adolescent↗
PubMed1989

Double mixing technique for linked enzyme assays.

A rapid double mixing technique has been applied to the reaction kinetics of enzymes usually analyzed by linked assay. The test enzyme is allowed to perform in the absence of the linking enzyme but then the convenience of enzymatic analysis of accumulated produce is exploited when a second mixing adds the linking enzyme. The analytical method is presented which enables the determination of the rate of product accumulation during the delay between mixings. Various advantages of the system in both steady-state and transient kinetic analyses are described. As an example, 3-phosphoglycerate kinase is assayed. The results address the proposal that the kinase interacts with the usual linking enzyme, glyceraldehyde-3-phosphate dehydrogenase, and also raise questions about product inhibition.

Animals↗
PubMed1989

Metabolic control and effect on secondary complications of diabetes mellitus by pancreatic transplantation.

After successful pancreatic transplantation blood glucose can be normalized without exogenous insulin, although oral and intravenous glucose tolerance remains impaired in 10-45% of the patients. There is no significant deterioration of glucose control with time in most patients. Since most recipients of pancreatic grafts have far advanced secondary diabetic lesions and the observation time after grafting is rather short, the effects of pancreatic transplantation on these complications are difficult to interpret. However, the development of diabetic nephropathy can be prevented, skin microcirculation improves significantly, while autonomic and peripheral neuropathy and diabetic retinopathy remain stable or improve slightly in most patients. But these ameliorations may be in part due to elimination of uraemia, since in almost all patients combined pancreas/kidney transplantations were performed. It is concluded that pancreas grafting probably has to be performed much earlier in the course of diabetes, although the improvement in the quality of life is striking even in the end-stage diabetics studied so far.

Blood Glucose↗
PubMed1989

[Pregnancies in females following kidney and pancreas transplantation].

Uraemic patients are in general infertile. Ovarian function is, however, restored after successful renal transplantation, thus making conception possible. We followed up 14 patients after renal transplantation involving 16 pregnancies. Two patients became pregnant twice, one with twins and the other following renal and pancreatic transplantation--the first recorded in the world. Caesarean section was performed in all patients due to increasing serum creatinin levels, avoid pre-eclampsia or premature rupture of membranes. Both, mother and child in all cases progressed without complications, although these pregnancies are associated with high risk for both. Therefore, a close co-operation between the mother, the nephrologist, the transplantation centre, the gynaecologist and the paediatrician is a prerequisite for a possible favourable course.

Abnormalities, Drug-Induced↗
PubMed1989

Fate of late complications in type I diabetic patients after successful pancreas-kidney transplantation.

The success rate of pancreas transplantation allows us to study in more detail the potential beneficial effects of normoglycemia on secondary complications in diabetes mellitus. We report a prospective follow-up (mean 26 mo) of metabolic control, neuropathy, retinopathy, and peripheral microcirculation in 31 patients with type I (insulin-dependent) diabetes (mean age 33 +/- 1 yr; mean duration of diabetes 21 +/- 1 yr) after combined kidney and segmental pancreas grafting. All patients had normal HbA1 levels. Glucose tolerance (GT), insulin, C-peptide, and glucagon were normal in 22 patients, and impaired oral GT with reduced insulin secretory capacity was seen in 9 patients. During follow-up, there was no deterioration of GT and insulin release. Vascular risk factors, e.g., hypertension, cholesterol, and triglycerides, decreased after grafting. Autonomic neuropathy improved clinically, and R-R variation increased significantly in 3 of 18 patients. Peripheral neuropathy improved clinically in 46% of patients and did not deteriorate in the others. Motor nerve conduction velocity increased greater than 20% in 8, less than 20% in 12, and was unchanged in 8 of 28 recipients. Most of the patients (n = 30) had pretransplant laser treatment of their advanced retinopathy. Posttransplant visual acuity improved at least more than one line in 56%, stabilized in 32%, and deteriorated in 12% of patients. Patients with functioning grafts for greater than 1 yr had no further deterioration of visual acuity. Vitreous hemorrhage frequency and severity dropped markedly from pretransplant (from 69 to 24%) 10 mo after grafting. Retinal morphology remained stable in all eyes except two.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Pregnancy after combined pancreas-kidney transplantation.

Four successful cases of pregnancy after combined pancreas-kidney transplantation at four different centers are summarized. The techniques used for the pancreas transplantations were duct obstruction in one patient and enteric exocrine diversion in two patients; in all three patients the insulin delivery was to the systemic circulation. In one patient exocrine diversion was to the stomach and the vascular anastomosis to the splenic vessels, thus accomplishing portal insulin delivery. Immunosuppression consisted of cyclosporin and prednisolone in two patients; cyclosporin alone in one patient; and cyclosporin, azathioprine, and prednisolone in one patient. In all a cesarean section was performed, due to deteriorating renal function in two patients, a fall in fetal growth in one patient, and fear of inducing pancreas-graft pancreatitis during normal delivery in one patient. In all four women, perfect metabolic control was retained throughout the pregnancy, and despite the proximity of the pancreas graft to the growing uterus in three of the women, the pancreas grafts did not suffer any damage during the pregnancy. However, in one patient the pancreas graft was lost in acute rejection after delivery. This pancreas had functioned normally for 3 yr before this occasion. Of the offspring, one was completely normal, one had a bilateral cataract, and two were small for date. The latter two subsequently showed normal growth development. At follow-up at 3, 5, 7, and 28 mo, all kidney grafts and three of the pancreas grafts remained functional. We conclude that after combined pancreas-kidney transplantation, successful conception and pregnancy can be obtained. Despite reduced islet mass (segmental grafts), normal metabolic control can be retained throughout the pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Behavioral characteristics of mouse pups during suckling. The oxytocin level in the blood of females during nursing].

Some characteristics of neuroendocrine milk-ejection reflex were studied during lactation in unanesthetized mice. Periods of considerable motor activity repeated regularly in the litter. The development of first reaction demands a prolonged stimulation of the nipple receptors by the litter. During an enhanced motor activity of the litter, the oxytocin concentration growth was determined with the radioimmunoassay of blood samples.

Animals↗
PubMed1989

Diminishing efficacy of octreotide (SMS 201-995) on gastric functions of healthy subjects during one-week administration.

In this study, the pharmacokinetics, efficacy, and tolerability of 25 and 100 micrograms of octreotide given t.i.d. for 7 days subcutaneously were investigated in 12 healthy male subjects. Serum concentrations of the drug were well reproducible within 1 wk. Octreotide significantly raised 24-h median intragastric pH on day 1, but no longer on day 6. Peptone-stimulated gastric acid and volume secretion were markedly less suppressed by octreotide on day 7 compared with day 2. Peptone-stimulated gastrin release was abolished on days 2 and 7, as was peptone-stimulated insulin release. Blood glucose was altered in a biphasic pattern on days 2 and 7. All effects of octreotide were without clear-cut dose-response relationship. A mean half-life of 115 min was calculated. Dose-unrelated side effects (e.g., abdominal cramps, diarrhea, and fatty stools) were registered. In conclusion, octreotide is a powerful inhibitor of gastric acid and volume secretion during acute treatment. Its loss of efficacy during a 1-wk administration may be due to the adaptation of somatostatin receptors and hormonal counterregulation.

Adult↗