Search PubMed⌕ Search

Biomedical subjects

P Schollmeyer

Publications and source records attributed to P Schollmeyer.

At least 19 recordsLinked to original sources
PubMed1992

[The long-term therapy of familial hypercholesterolemia with heparin-induced extracorporeal LDL precipitation].

The long-term tolerance to and effectiveness of heparin-induced extracorporeal LDL precipitation (HELP) in combination with lipid reducing drugs and diet was tested in six patient (5 males, 1 female; mean age 48 +/- 4 years). Follow-up period was over 50 months, in one patient over 24 months, while one man had a sudden cardiac death 57 weeks after starting treatment. The study was divided into three phases. In phase I (24 months) treatment consisted of HELP and conventional lipid-reducing drugs; in phase II (12 months) of lovastatin (80 mg daily) and cholestyramine (12-24 g daily); and phase III (14 months) of HELP, lovastatin and cholestyramine. In phase I it was possible to lower the pre-treatment level of LDL-cholesterol from 306 +/- 18 mg/dl to 173 +/- 13 mg/dl (43.5%). A similar effect (from 307 +/- 21 mg/dl to 155 +/- 17 mg/dl [-49.5%]) was obtained in phase II. The resumption of HELP reduced the pre-treatment LDL concentration to 136 +/- 9 mg/dl (-55.7%). The various treatment regimens were well tolerated. Biochemical data remained unchanged except for iron loss requiring substitution. Thus combined HELP, lovastatin and ion exchange offer for the first time an effective and reliable means in familial hypercholesterolaemia of clearly reducing long-term the mean LDL cholesterol level below the atherosclerosis threshold of 120 mg/dl.

Anticholesteremic Agents↗
PubMed1992

Effects of the novel dopamine DA2-receptor agonist carmoxirole (EMD 45609) on noradrenergic and purinergic neurotransmission in rat isolated kidney.

The effects of the classical dopamine DA2-receptor agonist quinpirole (LY 171555) and the recently characterized DA2-receptor agonist, carmoxirole (EMD 45609), on neurotransmission in rat isolated kidney were investigated. After preincubation with 3H-noradrenaline, the renal nerves were electrically stimulated. The stimulation induced (S-I) outflow of radioactivity was taken as an index of noradrenaline release. Quinpirole (0.3 mumol/l) inhibited S-I outflow of radioactivity and pressor-responses to renal nerve stimulation (RNS) at 1 Hz. Both effects of quinpirole were blocked by the DA2-receptor antagonist S(-)-sulpiride (10 mumol/l). The alpha 1, alpha 2-adrenoceptor antagonist phentolamine (1 mumol/l) did not block the inhibitory effect of quinpirole. Carmoxirole (0.003 and 0.03 mumol/l) did not alter and carmoxirole (0.3 mumol/l) even enhanced S-I outflow of radioactivity, however, pressor responses to RNS were markedly reduced by carmoxirole (0.003-0.3 mumol/l). Pressor responses to RNS were also markedly reduced by the alpha 1-adrenoceptor antagonist prazosin (0.1 mumol/l). Carmoxirole (0.3 mumol/l), prazosin (0.1 mumol/l) and phentolamine (1 mumol/l) totally abolished pressor responses to exogenous noradrenaline (0.05 mumol/l). In contrast, quinpirole (0.3 mumol/l) did not alter pressor responses to exogenous noradrenaline (0.05 mumol/l). Furthermore, carmoxirole (0.003-0.3 mumol/l) markedly reduced pressor responses induced by the alpha 1-adrenoceptor agonist methoxamine (1 mumol/l) but even the highest concentration of carmoxirole (0.3 mumol/l) had no effect on pressor responses induced by bolus injections of either neuropeptide Y (1.5 ng) or angiotensin II (1 ng). Phentolamine (1 mumol/l) by itself markedly enhanced S-I outflow of radioactivity and pressor responses to RNS were virtually unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1992

Activation of beta 2-adrenoceptors by isoprenaline and adrenaline enhances noradrenaline release in cortical kidney slices of young spontaneously hypertensive rats.

The aim of the present study was to investigate beta-adrenoceptor modulation of noradrenaline release from sympathetic nerves in superfused cortical kidney slices of 4-week-old spontaneously hypertensive rats (SHR) and age-matched controls (WKY). After preincubation with 3H-noradrenaline the kidney slices were electrically stimulated in superfusion chambers. The stimulation induced (S-I) outflow of radioactivity was mainly composed of unmetabolized 3H-noradrenaline in both strains and thus taken as an index of noradrenaline release. There was a frequency-dependent (1.25-20 Hz) increase in the S-I outflow of radioactivity. At all stimulation frequencies tested S-I outflow of radioactivity was similar or even slightly lower in SHR than in WKY kidney slices in either the absence or presence of cocaine (10 mumol/l). The non-selective beta-adrenoceptor agonists isoprenaline (0.1 mumol/l) and adrenaline (0.01 and 0.1 mumol/l) enhanced S-I outflow of radioactivity. The facilitatory effects of isoprenaline (0.1 mumol/l) and adrenaline (0.1 mumol/l) were blocked by the selective beta 2-adrenoceptor antagonist ICI 118551 (0.1 mumol/l) but not by the selective beta 1-adrenoceptor antagonist atenolol (0.3 mumol/l). The cell-permeable cAMP analogue 8-bromo-cAMP (300 mumol/l) enhanced S-I outflow of radioactivity to a similar extent in both SHR and WKY kidney slices. A combination of 8-bromo-cAMP (300 mumol/l) and adrenaline (0.1 mumol/l) did not enhance S-I outflow of radioactivity to a greater extent than 8-bromo cAMP (300 mumol/l) alone in both strains.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1992

Activation of alpha 1- and alpha 2-adrenoceptors inhibits noradrenaline release in rabbit renal arteries: effects of pertussis toxin and N-ethylmaleimide.

1. The effects of selective alpha 1- and alpha 2-adrenoceptor agonists and antagonists on the stimulation-induced (S-I) outflow of radioactivity at 2 Hz were investigated in superfused rabbit renal arteries incubated with [3H]-noradrenaline. 2. The alpha 1-adrenoceptor agonist methoxamine (10 microM) inhibited S-I outflow of radioactivity and this effect was abolished by the alpha 1-adrenoceptor antagonist prazosin (0.1 microM) but not by the alpha 2-adrenoceptor antagonist rauwolscine (1 microM). Neither the prostaglandin synthesis inhibitor indomethacin (10 microM) nor the adenosine receptor antagonist 8-phenyl-theophylline (1 microM) prevented the inhibitory effect of methoxamine. 3. The alpha 2-adrenoceptor agonists clonidine (0.1 microM) and UK 14304 (0.1 microM) both inhibited S-I outflow of radioactivity. The inhibitory effect of clonidine was blocked by rauwolscine but not by prazosin. The inhibitory effect of UK 14304 was markedly reduced by rauwolscine. 4. Prazosin (0.1 microM) alone did not enhance the S-I outflow of radioactivity at 2 Hz and slightly enhanced S-I outflow at 4 Hz. Rauwolscine (1 microM) alone markedly enhanced S-I outflow of radioactivity at 2 and 4 Hz. 5. Pretreatment of the arteries with pertussis toxin (1 microgram ml-1) did not significantly alter the inhibitory effects of methoxamine or UK 14304 or the potentiation by rauwolscine. However, pretreatment of the arteries with a higher concentration of pertussis toxin (5 micrograms ml-1) prevented the inhibitory effect of methoxamine but still did not affect the responses to UK 14304 and rauwolscine. 6. Pretreatment of the arteries with N-ethylmaleimide (NEM, 10 microM) for 30 min did not alter the inhibitory effect of methoxamine but markedly attenuated the inhibitory effect of UK 14304 and the facilitatory effect of rauwolscine. 7. The results suggest that both alpha 1- and alpha 2-adrenoceptors take part in the modulation of noradrenaline release from sympathetic nerves in rabbit renal arteries. Alpha 1-adrenoceptor mediated inhibition may be coupled to G-proteins which are pertussis toxin sensitive and alpha 2-adrenoceptor mediated inhibition to G-proteins which are NEM-sensitive.

Adrenergic alpha-Agonists↗
PubMed1992

Effect of nucleotides on the cytosolic free calcium activity and inositol phosphate formation in human glomerular epithelial cells.

1. Glomerular epithelial cells (GEC) were cultured from human kidneys and immunologically characterized. 2. The effect of extracellular nucleotides on the cytosolic free calcium activity [Ca2+]i was investigated with the fura-2 microfluorescence method. Extracellular UTP, UDP, UMP, ATP, adenosine 5'-O-(3-thio)-trisphosphate (ATP-gamma-S), inosine-triphosphate (ITP), guanyltriphosphate (GTP), 2-methylthio-ATP, AMP, alpha,beta-methylene-ATP and adenosine led to a rapid, transient, concentration-dependent increase of [Ca2+]i, followed by a plateau above the baseline level. 3. In a calcium-free extracellular solution, the rapid increase of [Ca2+]i was still present, whereas the plateau level was abolished. 4. ATP and UTP (ED50 both: 10(-5) M) stimulated inositol trisphosphate (InsP3) formation in GEC. 5. The order of potency for the purine nucleotides in stimulating InsP3 formation was ATP = ATP-gamma-S greater than ADP greater than 2-methylthio-ATP greater than AMP = a,beta methylene-ATP = adenosine. 6. The increase of InsP3 induced by ATP (10(-5) M) could be inhibited by the P2 receptor blocker suramin (greater than 10(-4) M). Reactive blue 2 exhibited a weak stimulating effect on the InsP3 formation and only a weak inhibitory effect at a concentration of 10(-3) M was observed. 7. Protein kinase C activation by preincubation of GEC with phorbol 12-myristate 13-acetate (PMA, 100 ng ml-1, 15 min) abolished the effect of ATP (10(-5) M) on InsP3 formation. Downregulation of protein kinase C by long term incubation (18 h) with PMA had no significant effect on the phosphoinositol turnover induced by ATP.8. The results indicate that an increase of [Ca2+]i and inositol phosphate breakdown can be mediated via activation of a P2 receptor in human GEC.

Adenosine Triphosphate↗
PubMed1992

Central nervous system lesions in von Hippel-Lindau syndrome.

CNS manifestations were studied in 97 gene carriers of von Hippel-Lindau syndrome (HLS). Haemangioblastomas of the CNS were found in 43 patients (44%), 23 females and 20 males. The mean age at diagnosis was 39 years (12-73 years). A total of 93 haemangioblastomas were detected of which 74% were intracranial and 26% were located in the spinal cord; 75% were predominantly cystic and 25% presented as solid lesions. Multiple lesions were found in 42% of HLS-associated haemangioblastomas, but in none of 51 patients with CNS haemangioblastoma without HLS. Haemangioblastoma was the cause of death in 82% of patients with HLS. Although microsurgery has considerably improved post-operative results, multifocal tumour development and recurrence remain a serious problem in the clinical management of HLS gene carriers.

Adolescent↗
PubMed1992

Effect of amino acid based dialysis solution on peritoneal permeability and prostanoid generation in patients undergoing continuous ambulatory peritoneal dialysis.

The acute effect of amino acid based dialysis solution on peritoneal kinetics of amino acids and plasma proteins in comparison to conventional glucose-based dialysate was studied in 9 patients with end-stage renal failure on continuous ambulatory peritoneal dialysis. Instillation of 2.6% amino acid solution resulted in raised plasma concentrations of all essential amino acids included in the dialysis fluid (p less than 0.005). The amino acid solution induced an augmented leakage of plasma proteins into the dialysate at all dwell times investigated (1-8 h). After a dwell time at 8 h, the dialysate total protein increased from 2.62 +/- 0.45 g with glucose dialysate to 3.85 +/- 0.42 g with amino acid solution (p less than 0.05). Corresponding results were obtained for beta 2-microglobulin, albumin, transferrin, IgG, and for the non-essential amino acids alanine, citrulline, and glutamine (p less than 0.025) not included in the initial amino acid composition of the dialysis fluid. During the use of amino acid based dialysis fluid, the effluent prostaglandin E2 concentration increased by more than 80% in comparison to glucose dialysate (p less than 0.025). The augmented loss of proteins induced by the amino acid solution was positively correlated with increased dialysate prostaglandin E2 (r = 0.8894; p less than 0.001). Peritoneal ultrafiltration was not affected by the use of amino acid based dialysate fluid. The present results indicate that amino acid based dialysis fluid enhances the peritoneal permeability for plasma proteins and amino acids, probably mediated by locally generated prostanoids.

Adult↗
PubMed1992

Effect of simvastatin on qualitative and quantitative changes of lipoprotein metabolism in CAPD patients.

The efficacy of simvastatin, a competitive inhibitor of 3-hydroxy-3-methyl glutaryl coenzyme A reductase, was investigated in 12 patients treated with continuous ambulatory peritoneal dialysis (CAPD), displaying hypercholesterolemia and moderate hypertriglyceridemia. After a 4-week placebo period, simvastatin was administered in increasing doses over a period of 3 months (1st month 10 mg; 2nd month 20 mg and 3rd month 40 mg day-1). Simvastatin reduced total serum cholesterol (300.0 +/- 15.5 vs. 193.0 +/- 8.0; -35%), LDL cholesterol (203.8 +/- 13.0 vs. 104.7 +/- 6.0; -48.0%) as well as apolipoprotein B (132.3 +/- 6.6 vs. 77.8 +/- 2.7 mg/dl; -40%). Furthermore, the ratio of LDL apo B/LDL cholesterol increased significantly (0.55 +/- 0.016 vs. 0.64 +/- 0.027). Another remarkable effect was the reduction of cholesterol concentration in VLDL (47.8 +/- 5.6 vs. 30.4 +/- 5.2; -35%). Therefore, the ratio of triglycerides/cholesterol in VLDL increased (3.57 +/- 0.3 vs. 4.28 +/- 0.29), indicating VLDL formation poor in cholesterol and rich in triglycerides. However, HDL cholesterol increased significantly from 48.6 +/- 4.4 to 57.9 +/- 5.3 mg/dl (23%). Lipoprotein(a) levels were increased as compared to controls (420 +/- 73 vs. 145 +/- 26 U/l), but were not influenced significantly by simvastatin treatment (539 +/- 99 U/l, 3rd month). No evidence for notable clinical side effects and laboratory abnormalities were reported. Measurement of simvastatin plasma levels 12 h after drug administration (single dose 40 mg) showed no detectable plasma values. At present, it appears that CAPD patients with high serum cholesterol are good candidates for the treatment with HMG-CoA reductase inhibitors.

Adult↗
PubMed1992

Effect of CAPD dialysate on the release of eicosanoids and cytokines from human peritoneal macrophages.

The effect of fresh peritoneal dialysis (PD) solution and effluent on the generation of eicosanoids and cytokines by human peritoneal macrophages (PMO) was studied in vitro. PMO, isolated by density gradient separation from patients undergoing intermittent peritoneal dialysis (IPD), were incubated for 2 h with PD effluent after dwell periods of 5 to 240 min or fresh PD solution. Supplemented RPMI-1640 medium served as control. PMO were stimulated by calcium ionophore A23187 (10 M). PD solution significantly inhibited the release of prostanoids (PGE2, TXB2, 6-k-PGF1), leukotrienes (LTB4, LTC4), and cytokines (11-6, TNF) from PMO by 60 to 96% (p < 0.05). Addition of A23187 increased the generation of TXB2, LTB4, and LTC4 in PD solution adjusted to pH 7.4 to 2.7 up to 28.6 times the basal level, but was ineffective in PD fluid at pH 5.2. Incubation of PMO with PD effluent of varying dwell times resulted in a rise of all assayed mediators (p < 0.05). The release of IL-6 increased continuously from 80 +/- 10 pg/10(6) PMO (0 min dwell time) to 440 +/- 104 pg/10(6) PMO (4 h dwell time, mean +/- S.E.M.). TNF generation rose from 6.0 +/- 0.1 pg/10(6) PMO (0 min dwell time) to 162 +/- 54 pg/10(6) PMO after 5 min dwell time and remained constant with effluents of longer dwell times (15 to 240 min). Exposure of PMO to PD effluents after 240 min dwell time tended to decrease the median levels of PGE2, TXB2, and 6-k-PGF1.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1991

[20 years kidney transplantation. Experience of a practice].

Between September, 1969, and May, 1990, 1,086 kidney transplantations were performed in Freiburg. In the majority of cases, the transplantations were allografts and had been made possible by close cooperation with the Eurotransplant Foundation. The results of this long-term study show that the transplant function rates at one year in the period under observation were comparable. Only the introduction of the immunosuppressive agent cyclosporine A brought about any improvement. On the basis of the results achieved at our center, the HLA system had an influence on transplantation function rate only in the case of the DR system. However, this does not mean that, for organ matching, the HLA system should no longer be complied with, since multicentric studies have substantiated its importance. High-risk groups, such as diabetics and elderly patients who undergo a transplantation achieve the same good results as the low-risk groups, provided that each case is carefully considered on its individual merits.

Adolescent↗
PubMed1991

Alpha 2-adrenoceptor activation inhibits noradrenaline release in human and rabbit isolated renal arteries.

The aim of the present study was to investigate alpha 2-adrenoceptor modulation of noradrenaline release in superfused strips of human and rabbit renal arteries. The arteries were field-stimulated after incubation with [3H]noradrenaline. The stimulation-induced outflow of radioactivity was taken as an index of noradrenaline release. At a high stimulation frequency (4 Hz), the alpha 2-adrenoceptor agonist clonidine (0.1 mumol/l) failed to inhibit stimulation-induced outflow of radioactivity in human and rabbit renal arteries whereas the alpha 2-adrenoceptor agonist UK 14304 (0.1 mumol/l) did inhibit stimulation-induced outflow. The inhibitory effect of UK 14304 in human renal arteries was blocked by the alpha 2-adrenoceptor blocking drug rauwolscine (1 mumol/l). At a lower stimulation frequency (2 Hz), both clonidine and UK 14304 inhibited stimulation-induced outflow of radioactivity from rabbit renal arteries; both effects were blocked by rauwolscine. Rauwolscine by itself enhanced stimulation-induced outflow of radioactivity in both preparations. The results suggest that activation of prejunctional alpha 2-adrenoceptors in human and rabbit renal arteries inhibits noradrenaline release. Neuronally released noradrenaline exerts inhibitory feed-back modulation of its own release through activation of prejunctional alpha 2-adrenoceptors. At a higher stimulation frequency most of the prejunctional alpha 2-adrenoceptors are already occupied by endogenous noradrenaline and clonidine fails to inhibit noradrenaline release since it seems to act as a partial agonist at these prejunctional alpha 2-adrenoceptors.

Adrenergic alpha-Agonists↗
PubMed1991

Blood flow dependent granulocyte activation in membranes with and without complement activation.

Synthetic membranes activate the complement system to some degree but also clear complement fragments from the circulation by adsorption and/or filtration and dialysis, PAN and PMMA even lower preexisting plasma levels of C3a. Activation of granulocytes measured as elastase release does occur with all membranes and might be due to complement activation. However, in synthetic membranes no correlation exists between levels of complement fragment C3a and elastase release. Instead, even when PMMA membrane lowered preexisting plasma levels of the C3a below baseline, activation of granulocytes to a similar degree as known from cuprophane membranes was observed. This activation did occur with blood flow of 200 ml/min during recirculation, but not without blood flow during incubation of membrane material. We conclude that granulocyte activation in synthetic membranes does not require an activated complement system, but may be a blood flow dependent phenomenon.

Acrylic Resins↗
PubMed1991

Pancreatic lesions in the von Hippel-Lindau syndrome.

Common manifestations of the von Hippel-Lindau syndrome, an autosomally dominant inherited cancer-prone disorder, include retinal angiomatosis, hemangioblastoma of the central nervous system, renal cysts, renal cancer, pheochromocytoma, and epididymal cystadenoma. Multiple cysts and microcystic (serous) cystadenomas of the pancreas have also been reported occasionally in patients afflicted with this syndrome. In the large Freiburg study of the von Hippel-Lindau syndrome composed of 66 affected individuals, pancreatic lesions were systematically studied. Fifty-five living individuals were examined by abdominal ultrasound imaging. Abnormal findings were confirmed by computed tomographic scan and/or magnetic resonance imaging. For an additional 11 decreased patients autopsy data were available. Cystic lesions of the pancreas were found in 10 patients (15%). One of these patients presented with multiple pancreatic cysts as the only manifestation of the syndrome. In one patient, a malignant islet-cell tumor was found at autopsy. Because multiple pancreatic cysts did not cause major clinical symptoms and because follow-up examinations over an average period of 5 years did not show significant progression of the lesions, it is concluded that these patients usually do not require surgical treatment. Abdominal ultrasound screening is recommended for patients at risk as a tool to identify potential von Hippel-Lindau syndrome gene carriers with pancreatic manifestations. In all patients with multiple pancreatic cysts, the von Hippel-Lindau syndrome should be included in the differential diagnosis.

Adolescent↗
PubMed1991

Effect of cell density on growth regulation of human glomerular epithelial cells. Inhibition of growth by dbcAMP and cAMP-elevating agonists.

Glomerular epithelial cells (GEC) play an important role in the development of focal glomerular sclerosis. A variety of growth factors and the local cellular environment contribute to growth regulation and development of GEC. To understand whether responsiveness of GEC to growth factors might be modulated by cell density, we investigated the influence of epidermal growth factor (EGF) on cell proliferation, as well as the role of transforming growth factor beta (TGF beta) on growth modulation in human visceral GEC in culture plated at different cell densities. Proliferation of cells was determined by [3H]thymidine incorporation. EGF and serum exhibited a dose-dependent stimulation independent of cell density in culture. Addition of TGF beta in concentrations greater than 0.1 ng/ml to cells prestimulated with EGF (1 ng/ml) and plated at densities of 18,000 and 50,000 cells per cm2 was followed by a significant growth inhibition. In contrast, cells plated at 5,000 cells per cm2 were not inhibited upon stimulation by TGF beta in this concentrations range (0.1 and 1.0 ng/ml). Heparin markedly inhibited serum-stimulated cell proliferation in concentrations of 1, 10, and 100 U/ml. De-N-sulphated- and low molecular weight heparin as well as glycosaminoglycans and sulphated polysaccharides (chondroitin sulphate A, B, C, heparan sulphate, dextran sulphate, and hyaluronic acid) failed to inhibit growth. Furthermore, proliferation of human GEC was significantly inhibited by the cAMP analogue dbcAMP (0.1 and 1 mM) and the cAMP-elevating agonists cholera toxin (250 ng/ml) and forskolin (10 and 100 microM). 1,9-Dideoxyforskolin had no effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Bucladesine↗