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T Weinreich

Publications and source records attributed to T Weinreich.

At least 19 recordsLinked to original sources
PubMed2006

Effects of an increase in time vs. frequency on cardiovascular parameters in chronic hemodialysis patients.

UNLABELLED: Cardiovascular mortality is still high and many risk factors are inadequately controlled in patients on conventional chronic hemodialysis. Recent studies on intensified treatment schedules by either increasing length or frequency of dialysis sessions have shown promising results with better control of blood pressure, reduction of left ventricular hypertrophy and easier control of calcium/phosphate metabolism. AIM: The present observational study compared the effect of different forms of "intensified dialysis treatment" i.e. either long nightly intermittent (LNHD, 3 x 7.5 - 8 h) or short daily dialysis sessions (DHD, 6 x 2.5 - 3 h) on cardiovascular parameters, phosphate and anemia control in comparison to standard treatment schedules (SHD, 3 x 4 - 5 h). METHODS: All patients stable on hemodialysis between 18 and 80 years of age and with either uncontrolled hypertension and/or left ventricular hypertrophy and/or frequent intradialytic hypotension, were asked to participate in intensified dialysis therapy by either LNHD or DHD. Patients not willing to change their dialysis regime were asked to participate as control group (SHD). Primary end point was 24-h ambulatory blood pressure, secondary end points were predialysis blood pressure, left ventricular mass index (LVMI) and fractional shortening (FS), control of calcium, phosphate and anemia. Patients were followed up for 1 year. RESULTS: 17 patients opted for LNHD, 8 for DHD, 19 patients served as control group. After 1 year of treatment 24-h blood pressure was unchanged in all groups. Predialysis systolic blood pressure decreased in LNHD and DHD, but increased in SHD. Mean LVMI decreased in all treatment groups (DHD -20.1 +/- 24.0%, SHD -13.6 +/- 33.4%, LNHD -6.1 +/- 32.2%). The mean number of antihypertensive tablets/day was reduced in DHD by 3.3 tablet units, in LNHD by 1.2 tablet units, but increased in SHD patients. FS improved in patients on LNHD and DHD, but decreased in patients on SHD. Regression of LVMI was independent of dry weight which was unchanged in LNHD and SHD but increased in DHD. In contrast to SHD, phosphate control and Ca x P product improved in DHD and LNHD with less phosphate binding tablets. Intact PTH did not change in SHD, but decreased in DHD and LNHD. Hemoglobin increased in groups on intensified treatments, but fell in SHD. EPO resistance index fell in LNHD, but increased in DHD and SHD. CONCLUSION: While reduction in 24-h blood pressure was not achieved by intensified dialysis, both schedules showed favourable effects on LVMI and FS with less antihypertensive medication. This was independent of reduction in dry weight. These effects were more pronounced in DHD patients. In contrast, in SHD patients, stable 24-h blood pressure and reduction in LVMI were achieved on the expense of an increasing amount of antihypertensive medication and with worsening of FS.

Adolescent↗
PubMed2001

Suppression of ICAM-1 expression in renal proximal tubular cells by 1,25-dihydroxyvitamin D3.

BACKGROUND: 1,25-Dihydroxyvitamin D(3) is mainly synthesized by renal proximal tubular cells. More recently, it has been shown to affect cell growth and TGF-beta(1) synthesis in glomerular and tubular renal cells in vitro, and to prevent glomerulosclerosis in vivo in subtotally nephrectomized rats. The mechanisms involved have not been fully identified. We asked whether 1,25-vitamin D(3) might interact with additional immunoregulatory functions of renal cells by studying its effects on the expression of the cellular adhesion molecules ICAM-1 (CD54) and VCAM-1 (CD106) in human proximal tubular cells in vitro (HK-2 cells). METHODS: Expression of adhesion molecules was assessed in HK-2 cells cultured under basal conditions and after stimulation with TNF-alpha plus IFN-gamma, by flow cytometry, gene transcription (RT-PCR) and measurement of soluble ICAM-1 in culture supernatant by ELISA. RESULTS: Unstimulated HK-2 cells did not express VCAM-1 and only little ICAM-1. 1,25-Vitamin D(3) had no effect on the expression of adhesion molecules in unstimulated cells. TNF/IFN stimulation resulted in a 4-fold increase in ICAM-1 and VCAM-1 expression. The TNF/IFN-induced increase in ICAM-1 expression was reduced by 1,25-vitamin D(3) dose dependently (10(-7) M vs. solvent: -30%; 10(-9) M: -18%; 10(-11) M: -17%). 25(OH)-vitamin D(3) had no effect. ICAM-1 mRNA concentration was increased in TNF/IFN-stimulated cells. 1,25-Vitamin D(3) treatment prevented the increase of ICAM-1 mRNA by 27% after 24-72 h incubation (p = 0.03). The TNF/IFN-induced increase in soluble ICAM in culture supernatants was unchanged by 1,25-vitamin D(3). VCAM-1 expression was unchanged by incubation with 1,25-vitamin D(3) under basal conditions and after TNF/IFN stimulation. CONCLUSION: 1,25-Vitamin D(3) inhibits cytokine-induced ICAM-1 but not VCAM-1 expression in renal proximal tubular cells in vitro. The present data support the hypothesis that 1,25-vitamin D(3) is not only synthesized by renal tubular cells, but may also affect immunoregulatory functions in these cells.

Calcifediol↗
PubMed2001

Effects of fluvastatin on cardiac events in renal transplant patients: ALERT (Assessment of Lescol in Renal Transplantation) study design and baseline data.

BACKGROUND: Recent clinical trials of primary and secondary prevention of cardiovascular disease have demonstrated that lowering plasma cholesterol with 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors ('statins') reduces morbidity and mortality from coronary heart disease in diverse patient populations. STUDY AIMS: The aim of the present ALERT (Assessment of Lescol in Renal Transplantation) study is to determine whether renal transplant recipients would also benefit from statin therapy. ALERT is a multicentre, randomized, double-blind, placebo-controlled trial to assess the effect of fluvastatin in renal transplant recipients with mild-to-moderate hypercholesterolaemia. The primary objective is to investigate the effects of fluvastatin on major adverse cardiac events (MACE). In addition, the effects on cardiovascular and all-cause mortality, as well as renal function, will be addressed. STUDY POPULATION: The study population contains patients with functioning renal allografts of more than 6 months' duration, recruited from 75 centres in Northern Europe and Canada. Patients of both sexes, aged 30-75 years, with a total cholesterol level of 4.0-9.0 mmol/l (155-348 mg/dl) were included, except for those with a history of myocardial infarction, where the upper limit for inclusion was 7.0 mmol/l (270 mg/dl). STUDY DESIGN: A total of 2100 patients were recruited by the end of October 1997 and will be followed for up to 6 years. This report presents the design features of the study (recruitment, follow-up, sample size, data analysis and study organization), along with baseline results. ALERT is the first large-scale prospective, randomized, double-blind study to address the prevention of cardiovascular mortality in renal transplant patients receiving an HMGCoA reductase inhibitor.

Adult↗
PubMed2000

Giant cell arteritis "causing" AA-amyloidosis with rapid renal failure.

Giant cell arteritis (GCA) is a systemic vasculitic disease, which in very rare cases causes inflammatory complications such as secondary amyloidosis. We describe a well-documented case, with a clinically mild course, of biopsyproven giant cell arteritis as the only apparent cause of systemic AA-Amyloidosis. The deterioration in renal function due to amyloid deposition occurred rapidly and only a few months after manifestation of giant cell arteritis and was not reversible by steroid treatment. The renal arteries were normal and there was no glomerulonephritis due to giant cell arteritis. This unique case demonstrates that giant cell arteritis with a mild clinical course is closely associated with early-onset severe secondary amyloidosis.

Acute Kidney Injury↗
PubMed1999

Reduced kidney transplant rejection rate and pharmacoeconomic advantage of mycophenolate mofetil.

BACKGROUND: Several multinational controlled clinical trials have shown that triple therapy immunosuppressive regimens which include mycophenolate mofetil (MMF), cyclosporin A (CSA) and steroids (S) are superior compared with conventional regimens which include azathioprine (AZA), CSA and S, mainly because MMF reduces the rate of acute rejection episodes in the first 6 months after kidney transplantation. Post-marketing studies are useful to evaluate the general applicability and costs of MMF-based immunosuppressive regimens. METHODS: Based on the excellent results of the published controlled clinical trials, we have changed the standard triple therapy immunosuppressive protocol (AZA+CSA+S) to an MMF-based regimen (MMF+CSA+S) at our centre. To analyse the impact of this change in regimen, we have monitored 6-month patient and graft survival, rejection rate, serum creatinine and CSA levels, as well as the costs of the immunosuppressive and anti-rejection treatments, in 40 consecutive renal transplant recipients (MMF group) and have compared the data with 40 consecutive patients transplanted immediately prior to the change in regimen (AZA group). RESULTS: Recipient and donor characteristics were similar in the AZA and MMF groups. Patient survival (37/40; 92.5% in the AZA group vs 38/40; 95% in the MMF group), graft survival (36/40 vs 36/40; both 90%) and serum creatinine (137+/-56 vs 139+/-44 micromol/l) after 6 months were not significantly different. However, the rate of acute rejection episodes (defined as a rise in creatinine without other obvious cause and treated at least with pulse steroids) was significantly reduced with MMF from 60 to 20% (P=0.0005). The resulting cost for rejection treatment was lowered 8-fold (from sFr. 2113 to 259 averaged per patient) and the number of transplant biopsies was lowered > 3-fold in the MMF group. The cost for the immunosuppressive therapy was increased 1.5-fold with MMF (from sFr. 5906 to 9231 per patient for the first 6 months). CONCLUSIONS: The change from AZA to MMF resulted in a significant reduction in early rejection episodes, resulting in fewer diagnostic procedures and rehospitalizations. The optimal long-term regimen in terms of patient and pharmacoeconomic benefits remains to be defined.

Adult↗
PubMed1999

Malignant fibrous histiocytoma and atypical fibroxanthoma in renal transplant recipients.

BACKGROUND: Allograft recipients are at increased risk for skin cancer. The incidence of cutaneous squamous cell carcinoma is 50-250 times higher than in the age-matched control population, and basal cell carcinoma is about 10 times more frequent. The incidence of Kaposi's sarcoma is increased 400 to 500 times over that in a control population of the same ethnic origin. However, the incidence of other types of cutaneous sarcoma in organ allograft recipients is largely unknown. CLINICAL OBSERVATION: Within a 2-year-period, we observed 2 patients with cutaneous malignant fibrous histiocytoma and 1 patient with atypical fibroxanthoma among a cohort of 642 renal transplant recipients. For comparison, the incidence for dermatofibrosarcoma protuberans which is the commonest type of cutaneous sarcoma, is 0.45/100,000 persons/year in the non-immunocompromised population. Our observation represents an incidence of 156/100,000/ year (95% confidence interval Cl 28-489/100,000/year) for cutaneous malignant fibrous histiocytoma and of 78/100,000/year (95% CI 4-368/ 100,000/year) for atypical fibroxanthoma. CONCLUSION: To our knowledge, this is the first report on an elevated incidence of cutaneous malignant fibrous histiocytoma and of atypical fibroxanthoma in renal transplant recipients. Future cohort studies on malignancies in organ allograft recipients should aim at defining this risk more exactly.

Aged↗
PubMed1999

1,25-dihydroxyvitamin D3 stimulates transforming growth factor-beta1 synthesis by mouse renal proximal tubular cells.

1,25-dihydroxyvitamin D3 [1,25-(OH)2 D3] is a secosteroid hormone with effects on cell growth, differentiation and immunoregulatory functions in a number of tissues not primarily involved in mineral metabolism. We recently demonstrated growth-regulating effects of 1, 25-(OH)2 D3 on human mesangial cells and proximal tubular cells. To investigate whether 1,25-(OH)2 D3 might also affect the synthesis of cytokines and growth factors in proximal tubular cells, we assessed in the present study the expression and secretion of transforming growth factor-beta1 (TGF-beta1) in a mouse proximal tubular cell line (MCT) in vitro. TGF-beta1 synthesis was measured by a monospecific ELISA in culture supernatant. The secreted TGF-beta1 was proven to be biologically active by means of a bioassay system (CCL-64 mink lung epithelial cell proliferation assay). TGF-beta1 gene expression was assessed by RT-PCR. To analyze whether TGF-beta1 expression mediates the 1,25-(OH)2 D3-induced antiproliferative actions in MCT, proliferation studies in the absence or presence of a blocking monoclonal anti TGF-beta1-3 antibody were performed. 1, 25-(OH)2 D3 (10(-11) to 10(-7) M) specifically increased the TGF-beta1 protein secretion in MCT with a maximum at 10(-8) M. No detectable effect was found with 25 D3 at 10 times higher concentrations. A synthetic 20-epi analogue, MC 1288, increased TGF-beta1 secretion up to similar amounts at equimolar concentrations as the natural hormone 1,25-(OH)2 D3. Steady-state TGF-beta1 mRNA concentration in MCT was transiently increased by 1, 25-(OH)2 D3 between 12 and 24 h, returning to control values at 48 h. Blocking TGF-beta1 did not reduce or abrogate the antiproliferative effect of 1,25-(OH)2 D3. In conclusion, 1,25-(OH)2 D3 stimulates TGF-beta1 expression in renal proximal tubular cells, a growth factor with anti-inflammatory and profibrotic actions which plays an important role in the development and progression of nephrosclerosis.

Animals↗
PubMed1999

Insulin-like growth factor 1 and 2 serum concentrations in dialysis patients with secondary hyperparathyroidism and adynamic bone disease.

BACKGROUND: Insulin-like growth factor-1 and -2 exert well characterized effects on bone metabolism via paracrine and endocrine pathways. However, the role of circulating levels of IGFs and their binding proteins (IGFBP) in renal bone disease is still controversial. PATIENTS AND METHODS: To investigate whether circulating IGFs play a role in the pathogenesis of different forms of renal bone disease, we performed a cross sectional study in 38 stable dialysis patients (32 hemodialysis, 6 peritoneal dialysis). Patients were selected for the type of bone disease according to biochemical bone markers and bone histology. 25 Patients had adynamic bone disease (ABD; defined by plasma iPTH < 1,5 fold the upper limit of normal). Thirteen patients had secondary hyperparathyroidism (sHPT; defined by plasma iPTH > 10 fold the upper limit of normal). Serological diagnosis was confirmed in a subgroup of patients by bone histology (12 patients with type IIa according to Delling, ABD; 9 patients with type IIIb according to Delling, sHPT). Patients with signs or symptoms of aluminum toxicity were excluded from the study. RESULTS: Serum IGF-1 and -2 concentrations were comparable in both groups and were within the reported normal range for an age matched healthy control population. They did not correlate with biochemical markers (iPTH, bAP, osteocalcin) or histological manifestations of renal bone disease. Furthermore, semiquantitative analysis of IGFBP-2 and -3 carried out in patients with bone biopsies did not correlate with biochemical markers or histological indices of renal bone disease. CONCLUSION: In conclusion, in contrast to previous reports, the present data do not confirm a correlation between serological or histological markers of renal osteodystrophy and circulating IGF-1 or -2 or IGFBP-2 and -3. This does not exclude that potential alterations of the local IGF system may play a role in the pathogenesis of uremic bone disease.

Chronic Kidney Disease-Mineral and Bone Disorder↗
PubMed1998

Prevention of renal osteodystrophy in peritoneal dialysis.

BACKGROUND: Renal osteodystrophy (ROD) is still one of the major long-term complications in end-stage renal disease leading to considerable morbidity. Despite some progress in understanding the pathogenesis of secondary hyperparathyroidism (sHPT) during recent years, prevention and treatment of ROD is still suboptimal, requiring surgical parathyroidectomy in 6 to 10% of all patients on dialysis after 10 years. In addition, the spectrum of bone lesions has changed, with non-aluminum-related adynamic bone disease (ABD) found in up to 43% of peritoneal dialysis (PD) patients. METHODS: Current recommendations concerning prevention of ROD in PD based on the literature and personal recent data were reviewed. The focus is on (i) the importance of early prophylactic intervention to prevent parathyroid gland hyperplasia, (ii) the pathogenesis of ABD, and (iii) the role of metabolic acidosis in ROD. RESULTS: There is ample evidence that sHPT starts early during the course of renal failure and results from both hypersecretion of PTH by parathyroid cells and glandular hyperplasia. As shown by experimental and clinical studies, established parathyroid cell hyperplasia is hardly reversible by pharmacological means, and therefore prevention of parathyroid cell proliferation needs to start early. Recent data from randomized trials document the efficacy and safety of low dose active vitamin D (0.125 to 0.25 microgram/day) and/or an oral calcium substitute to prevent progression of sHPT in patients with mild to moderate renal failure. Since little is known about the pathogenesis, natural course and clinical impact of ABD in PD, specific therapeutic concepts have not yet been generated. Diabetes and advanced age are established risk factors, whereas the role of calcium and vitamin D overtreatment or the type of dialysis (PD vs. HD) are still controversial. Currently no evidence for different functional behavior of the parathyroids in ABD and sHPT has been found. The role of circulating or local factors such as cytokines, growth factors or the presence of advanced glycation end-product (AGE)-modified matrix proteins for the pathogenesis of either type of ROD deserves further investigation. Avoiding oversuppression of parathyroid gland and the use of low calcium dialysate may help prevent ABD. There is growing evidence that a correction of metabolic acidosis will influence ROD by both direct effects on the bone and on parathyroid cell function. New dialysate composition for CAPD with a high HCO3 concentration will allow normalization of acid-based metabolism in PD patients. Their effects on ROD under long term conditions remain to be determined. CONCLUSION: Therapeutic efforts should aim to prevent the development of parathyroid gland hyperplasia and sHPT early during the course of renal failure, and should include the use of low dose vitamin D therapy and oral calcium substitution as well as correction of metabolic acidosis. Concerning ABD, more information is needed regarding the causes and consequences of this type of bone lesion to develop a more specific therapy.

Acidosis↗
PubMed1996

1,25-dihydroxyvitamin D3 and the synthetic vitamin D analogue, KH 1060, modulate the growth of mouse proximal tubular cells.

Apart from its classical role in bone and mineral metabolism, 1,25-dihydroxyvitamin D3 (1,25-vitamin D3) has recently been shown to affect cell growth and differentiation from a variety of tissues primarily not involved in mineral metabolism and to provide immunomodulatory functions. Findings in human mesangial cells in vitro as well as in rat model of compensatory renal growth in vivo suggest that renal cells are a target for 1,25-vitamin D3. In the present study the effects of 1,25-vitamin D3 and a synthetic vitamin D analogue, KH 1060, on proliferation and protein synthesis were investigated in a mouse proximal tubular cell line (MCT). 1,25-vitamin D3 and KH 1060 inhibited cell proliferation dose dependently (10(-7) to 10(-12) M) and specifically as assessed by 3H-thymidine incorporation (DNA synthesis) and cell counting. The cellular protein concentration, protein synthesis (3H-methionine incorporation) and protein/DNA ratio were not influenced by 1,25-vitamin D3 and KH 1060. By analyzing c-fos and c-myc expression using semiquantitative RT-PCR, a constant basal expression of both protooncogenes, even under serum-free conditions, was found in MCT cells. Phorbol 12-myristate 13-acetate (TPA) further stimulated c-fos and c-myc expression, whereas treatment with 1,25-vitamin D3 (10(-7) M) it had no effect either in unstimulated or in TPA-stimulated cells. In conclusion, 1,25-vitamin D3 and a synthetic vitamin D analogue, KH 1060, provide growth-regulating effects on renal proximal tubular cells in vitro. These effects are not mediated by regulation of c-fos and c-myc. Further studies will have to clarify whether 1,25-vitamin D3 plays a physiologic role in renal development and growth in vivo.

Animals↗
PubMed1996

Comparison of two antilymphocyte globulins replacing cyclosporin A after first kidney allotransplantation and prolonged graft ischemia.

ATG/Fresenius (5 mg/kgBW) and ATGAM (Upjohn, 12.5 mg/ kgBW) replacing cyclosporin A were given during 7 d after transplantation to 20 patients in 1992 and 30 patients in 1993, respectively. Numbers of mismatches, combined kidney-pancreas transplantation and severe infections were not different for the two groups. However, prednisone pulse therapies and additional antilymphocyte globulin treatments were more frequent after ATGAM than after ATG induction (p < 0.01, chi 2-test).

Antilymphocyte Serum↗