Biomedical subjects
K H Rahn
Publications and source records attributed to K H Rahn.
Protein kinase C and calcium distribution in vascular smooth muscle cells from spontaneously hypertensive rats.
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Increased intracellular calcium response in glomerular mesangial cells from spontaneously hypertensive rats.
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Tissue-specific differences of cytosolic free sodium in spontaneously hypertensive rats.
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Effects of different antihypertensive agents on the overall cardiovascular risk profile.
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Therapeutic efficiency of phlebotomy in posttransplant hypertension associated with erythrocytosis.
Hypertension is a major complication in kidney transplantation and contributes to the high cardiovascular mortality of renal transplanted recipients. The aim of the present study was to evaluate the therapeutic effect of phlebotomy on blood pressure in posttransplant hypertension associated with erythrocytosis. In 12 renal transplanted patients (7 male, 5 female, aged 29-52 years) with erythrocytosis (defined by hematocrit > 52% or hemoglobin > 170 g/l), a 24-hour-monitoring of blood-pressure and heart rate (SpaceLabs SL90207) was performed before, 2 and 6 weeks after phlebotomy. Patients with iron-deficiency and/or transplant rejection were excluded from the study. Ten of 12 patients were on antihypertensive treatment before phlebotomy. Phlebotomy (500 ml) was repeated three times on average within the first two weeks, until hematocrit decreased below 45%. The phlebotomy therapy lowered the hematocrit after two weeks from 54.8 +/- 2.8% to 44.3 +/- 4.2% and 43.0 +/- 5.6% after six weeks. Before phlebotomy, the blood pressure was systolic 153.2 +/- 15.1 mmHg and diastolic 95.2 +/- 9.5 mmHg. After repeated phlebotomy, there was a significant decrease of blood pressure to systolic 139.0 +/- 14.1 and diastolic 85.3 +/- 8.2 mmHg (p < 0.01). Without change of hematocrit and hemoglobin, there was no further change of blood pressure after six weeks (systolic 140.1 +/- 9.9 mmHg, diastolic 86.3 +/- 9.5 mmHg). The heart rate did not change significantly during the therapy. The antihypertensive treatment could be reduced in most of the patients. The present study demonstrates the therapeutic effect of phlebotomy in posttransplant hypertension associated with erythrocytosis.(ABSTRACT TRUNCATED AT 250 WORDS)
[Stroke, epilepsy and abdominal pain as leading symptoms in a case of mitochondrial encephalomyopathy].
A 17-year old girl presented with recurrent seizures, strokes, fatigue, vomiting, cerebellar ataxia, dementia and hypertrichosis. Further examinations showed jerking left-sided arm reflexes, partial internal deafness and myopathy. CT and MR of the skull revealed radiolucencies within the cerebral matter of the cortex and the medulla. Laboratory tests showed increased levels of lactate and pyruvate in serum and cerebro-spinal fluid. Microscopic examination of muscular tissue showed "ragged red fibers". Electron microscopy yielded crystal inclusions in mitochondria. The symptoms represented the complete picture of the so-called MELAS/MERRF-complex, which can be easily misdiagnosed as strokes and seizures of unknown cause.
[Young patient with hypotension, constipation and urinary retention].
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[Reserpine and reserpine-containing preparations in hypertension?].
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Clinical experience with dual-acting drugs in hypertension.
There are now several antihypertensive agents with dual actions. Among these, labetalol has been studied most extensively. The drug has a place in the chronic treatment of hypertension and in the therapy of hypertensive emergencies. Carvedilol, now available in Germany, has been shown to be effective in different forms of hypertension. Celiprolol binds to beta 1- and beta 2-receptors. This drug also binds to alpha 2-receptors. It is not clear, at present, whether or not this binding property contributes to its antihypertensive effect.
Erythropoietin in thrombotic thrombocytopenic purpura and acute renal failure.
In this study, erythropoietin serum levels were serially determined in eight patients with acute renal failure to get a lead on the etiology of anemia in acute renal failure and to address the relationship between erythropoietin synthesis and renal excretory performance. Erythropoietin serum levels rapidly decreased after onset of acute renal failure to values of 12.8 +/- 10.3 mU/ml compared to 16.8 +/- 9.4 mU/ml in healthy controls. After restoration of renal function, erythropoietin levels climbed slowly in six patients (15.2 +/- 5.3 mU/ml), and in relation to prolonged anemia in these patients, a relative deficiency of erythropoietin could be observed. In one patient with thrombotic thrombocytopenic purpura causing acute renal failure, the decline of erythropoietin secretion was not observed, and in a phase of the disease when plasma exchange therapy was interrupted, markedly increased erythropoietin levels, up to 182 mU/ml, were detected despite the renal failure. Focusing on erythropoietin secretion in thrombotic thrombocytopenic purpura, we followed hormone synthesis in two other patients with the same disease, one of whom had mild renal insufficiency and one had normal renal function. High erythropoietin levels of up to 205 mU/ml were found in these patients, similar to the peak levels found in the patient with complete renal failure. Plasmapheresis treatment reduced erythropoietin production in all three patients with thrombotic thrombocytopenic purpura. In summary, our study indicates that in most cases of acute renal failure, erythropoietin synthesis is compromised and may contribute to the development of anemia in renal failure and aggravate the persistence of anemia after restoration of renal function.(ABSTRACT TRUNCATED AT 250 WORDS)
Mechanisms of ciclosporin A-induced vasoconstriction in the isolated perfused rat kidney.
Hypertension is a well-known side effect of ciclosporin A (CsA). In the present study the mechanisms of vasoconstriction in renal vessels were examined in the isolated perfused rat kidney. Kidneys were perfused with constant flow at a temperature of 37 degrees C with Tyrode's solution equilibrated with 95% O2/5% CO2. CsA was dissolved in ethanol. 500 and 2000 ng/ml increased resistance of renal vessels by 0.97 +/- 0.55 x 10(5) and 2.29 +/- 1.33 x 10(5) dyn s cm-5, respectively (mean values +/- SD, n = 12). The vasoconstriction developed gradually over 4 min. The vasopressor effect of CsA was not changed by saralasin (10(-6) M), nifedipine (10(-6) M) and ketanserin (10(-6) M), but was completely blocked by phentolamine and prazosin (each 10(-6) M). CsA-induced vasoconstriction was not prevented by perfusion with Ca(2+)-free solution containing 2 mmol EGTA. Similarly, pretreatment with reserpine to deplete sympathetic nerve endings from catecholamines did not affect CsA-induced vasoconstriction. The findings suggest that CsA-induced vasoconstriction is mediated by stimulation of alpha 1-receptors. Ca2+ influx does not play a role for CsA-induced vasoconstriction. Prolonged perfusion of rat kidneys with the vehicle cremophor EL elicits an irreversible increase in perfusion pressure.
[Diuretics. Range of effect, indications and therapeutic results in heart diseases].
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[Pentamidine inhalation in prevention of pneumocystis carinii pneumonia in treatment of rejection with monoclonal antibody Orthoclone (OKT-3)].
The use of the monoclonal antibody OKT-3 (Orthoclone) is associated with an increased risk of pneumocystis carinii pneumonia. In a retrospective study, the efficiency of a prophylactic inhalation of pentamidine during acute renal allograft rejection therapy with OKT-3 was investigated. From July 1988 until October 1989 32 renal transplanted patients with acute rejection refractory to steroids had been treated with OKT-3. Twelve of the patients developed a pneumonia (four pneumococcus, one klebsiella, one cytomegalovirus), in six cases, a pneumocystis carinii infection was diagnosed in the bronchial lavage. Four of these patients with pneumocystis carinii pneumonia died despite high dose treatment with cotrimoxazole. From November 1989, a prophylactic inhalation of pentamidine was performed during acute renal allograft rejection therapy with OKT-3. From 33 patients, in eleven cases, a pneumonia was diagnosed (three pneumococcus, one klebsiella, two legionella, three cytomegalovirus, one candida), one patient developed a pneumocystis carinii pneumonia, which was successfully treated with cotrimoxazole. No patient in this group died because of pulmonary infection. The results suggest, that a prophylactic inhalation of pentamidine in severely immunosuppressed solid organ transplant recipients can prevent pneumocystis carinii pneumonia.
Pentamidine inhalation as a prophylaxis against Pneumocystis carinii pneumonia after therapy of acute renal allograft rejection with orthoclone (OKT3).
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Direct vasopressor effect of recombinant human erythropoietin on renal resistance vessels.
The contractile properties of recombinant human erythropoietin (rHuEPO) on isolated resistance vessels of renal and mesenteric vascular beds were studied in an in vitro model using a small vessel myograph. Under isometric conditions, rHuEPO caused a contraction of this vasculature in a concentration range between 10 U/ml and 200 U/ml. A maximal active wall tension of 1.52 +/- 0.19 mN/mm was obtained under a rHuEPO dose of 200 U/ml. In Ca2+ free solution, the pressor response to high rHuEPO-concentrations was attenuated, and the response to low rHuEPO concentrations was abolished. In the presence of verapamil, phentolamine and saralasin, rHuEPO-induced contractions were not affected significantly. A dose-dependent vasodilatation of mounted vasculature to acetylcholine (ACh) indicated that endothelium remained intact in our preparations. rHuEPO-induced vessel contraction was not abrogated after an enzymatical removal of endothelium by collagenase, confirming that the described contractile responses are endothelial independent. These findings suggest that a direct vasopressor effect of rHuEPO on proximal resistance vessels may contribute to development of hypertension seen in rHuEPO-treated hemodialysis patients.
Comparison of the antihypertensive effects of delapril and enalapril.
The angiotensin converting enzyme (ACE) inhibitors delapril and enalapril were compared in a double-blind, randomized, parallel study. The population included 142 patients with essential hypertension who were treated with delapril and 140 treated with enalapril. At the end of a 2 week initial placebo period, the diastolic blood pressure of these patients ranged from 95 to 115 mm Hg in the sitting position. After this placebo period, randomization took place. Patients in the delapril group received 15 mg of the drug twice daily. Treatment with enalapril was started with a daily dose of 10 mg. If the diastolic blood pressure did not fall to less than or equal to 90 mm Hg or at least by 15 mm Hg after 2 weeks of treatment, the doses of the ACE inhibitors were doubled. After another 2 weeks, 25 mg hydrochlorothiazide daily was added if the target level of diastolic blood pressure was not reached. Both drugs caused a similar decrease of systolic and diastolic blood pressure. The antihypertensive effect of both ACE inhibitors was increased by the addition of the diuretic. The frequency and severity of side effects were similar in the two groups of patients. It is concluded from this study that delapril and enalapril do not differ in antihypertensive efficacy nor in safety.
Evaluation of the Ca2+ distribution in aortic tissue of spontaneously hypertensive and normotensive rats.
In the present study, particle-induced X-ray emission (PIXE) was used to get information on the spatial distribution of Ca2+ in aortas of spontaneously hypertensive rats (SHR) and normotensive controls aged 1 week, 4 weeks, and 12 weeks. To differentiate changes in Ca2+ metabolism in hypertensive arteries from secondary phenomena due to the arteriosclerosis, the animals were examined in the earliest stage of hypertension. It was found that the Ca2+ content was not elevated in the aortic smooth muscle of SHR aged 1 week (n = 11), as compared to normotensive controls (n = 10) (186.8 +/- 89.9 micrograms Ca2+/g tissue v 254.0 +/- 173.3 micrograms Ca2+/g). The Ca2+ content was raised (P less than .05) in the aortic smooth muscle of SHR aged 4 weeks (n = 13), as compared to 12 WKY rats (4 weeks) (726.0 +/- 130.4 micrograms Ca2+/g tissue v 440.3 +/- 214.4 micrograms Ca2+/g) and in 17 SHR (3 months), as compared to 13 WKY rats, respectively (3390.1 +/- 729.9 micrograms Ca2+/g tissue v 1632.1 +/- 569.5 micrograms Ca2+/g). The results confirm the age-related increase in the arterial Ca2+ content in normotensive rats and demonstrate additionally that this age-related rise in arterial Ca2+ content is accelerated in SHR.