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Biomedical subjects

R Ziegler

Publications and source records attributed to R Ziegler.

At least 73 records · Page 4Linked to original sources
PubMed1999

Octreotide (somatostatin analog) treatment reduces endothelial cell dysfunction in patients with diabetes mellitus.

Octreotide is a long-acting somatostatin analog that has been shown to have various effects in diabetes. This study was performed to evaluate whether octreotide affects the vascular complications of diabetes mellitus. Albuminuria and serum thrombomodulin were used as markers of vascular and renal dysfunction. We studied the effect of octreotide in 27 patients with insulin-dependent diabetes mellitus (IDDM). They received 200 microg octreotide per day over a period of 6 months. As a marker of endothelial cell damage, we measured the serum thrombomodulin level. We also measured urinary albumin excretion, hemoglobin A1c (HbA1c), insulin-like growth factor-1 (IGF-1), and other parameters. IGF-1 decreased from 123 ng/mL before treatment to 114 ng/mL after 6 months of octreotide treatment (P = .009), while no significant change was observed in the unblinded control group (from 103 ng/mL to 102 ng/mL after 6 months of treatment). Urinary albumin excretion in patients with macroalbuminuria declined from 1,124 mg/L before octreotide treatment to 556 mg/L after 6 months of treatment (P < .05), whereas no change was observed in the control group. There was also a reduction of the plasma thrombomodulin level from 61.8 ng/mL to 46.1 ng/mL (P < .07) after 6 months of treatment. Furthermore, HbA1c decreased from 8.75% +/- 1.27% to 8.12% +/- 1.23% (P < .07) after octreotide treatment.

Adult↗
PubMed1999

alpha-Lipoic acid decreases oxidative stress even in diabetic patients with poor glycemic control and albuminuria.

In the present cross-sectional study, the influence of alpha-lipoic acid on markers of oxidative stress, assessed by measurement of plasma lipid hydroperoxides (ROOHs), and on the balance between oxidative stress and antioxidant defence, determined by the ratio ROOH/(alpha-tocopherol/cholesterol), was examined in 107 patients with diabetes mellitus. Patients receiving alpha-lipoic acid (600 mg/day for > 3 months) had significant lower ROOHs and a lower ROOH/(alpha-tocopherol/cholesterol) ratio than those without alpha-lipoic acid treatment [ROOH: 4.76 +/- 2.49 vs. 7.16 +/- 3.22 mumol/l; p < .0001] and [ROOH/(alpha-tocopherol/cholesterol): 1.37 +/- 0.72 vs. 2.16 +/- 1.17; p < 0.0001]. In addition, the influence of glycemic control and albuminuria on ROOHs and on the ratio of ROOH/(alpha-tocopherol/cholesterol) was examined in the presence and absence of alpha-lipoic acid treatment. Patients were subdivided into three groups based on (1) their HbA1 levels (< 7.5, 7.5-9.5, and > 9.5%) and (2) their urinary albumin concentrations (< 20, 20-200, and > 200 mg/l). Neither poor glycemic control, nor the presence of micro- or macroalbuminuria prevented the antioxidant effect of alpha-lipoic acid. Using stepwise multiple regression analysis, alpha-lipoic acid was found to be the only factor significantly predicting low ROOHs and a low ratio of ROOH/(alpha-tocopherol/cholesterol). These data provide evidence that treatment with alpha-lipoic acid improves significantly the imbalance between increased oxidative stress and depleted antioxidant defence even in patients with poor glycemic control and albuminuria.

Albuminuria↗
PubMed1999

Age-related changes in insulin-like growth factor I and II in human femoral cortical bone: lack of correlation with bone mass.

The concentration of insulin-like growth factor-I (IGF-I) in human cortical bone declines with age, but the relevance of this decline for cortical bone turnover and bone mass is unknown. In the present study, we simultaneously assessed the concentration of IGF-I and -II in cortical bone matrix and histomorphometric parameters of bone mass and bone turnover in 125 samples from the proximal human femur shaft. Bone width decreased by 27% and porosity increased by 100% in female cortical bone between the fourth and the ninth decade. Similar, but weaker, changes tended to occur in male cortical bone. The concentrations of both IGF species were correlated with the percentage of osteons undergoing bone remodeling. However, despite age-related decreases in both IGF species in men and in IGF-I in women, neither of the IGFs accounted for age-related or age-independent variability in cortical porosity or bone width. In conclusion, these data suggest that the local concentrations of IGF-I and -II are related to cortical bone turnover. In contrast, our study provides no evidence for a major role of bone matrix IGF-I and -II as determinants of cortical bone mass in elderly individuals. Whether other components of the IGF system may be stronger determinants of cortical bone loss remains to be determined.

Adult↗
PubMed1999

Transforming growth factor beta (TGF-beta) levels in the conditioned media of human bone cells: relationship to donor age, bone volume, and concentration of TGF-beta in human bone matrix in vivo.

Transforming growth factor-beta (TGF-beta) is thought to play an important role in human bone remodeling. In the present study, we examined constitutive differences in TGF-beta levels in primary bone cell cultures from the iliac crest of 112 women, aged 28-79 years. TGF-beta1 was the major TGF-beta isoform in the conditioned media, as determined by neutralizing TGF-beta activity with specific antibodies against TGF-beta1-3 in the mink lung cell bioassay, and by enzyme-linked immunoassay (ELISA). TGF-beta1 levels in the conditioned media did not change with donor age. There was a lack of association between TGF-beta levels in vitro and the concentration of matrix-associated TGF-beta in vivo. TGF-beta1 levels failed to be associated with the local trabecular bone volume in the complete study population (r = +0.15, p = 0.16, n = 89). A significant association between TGF-beta1 levels and bone volume was present in premenopausal women (r = +0.39, p = 0.02, n = 33), but was largely accounted for by the two samples with the highest TGF-beta concentrations. In conclusion, our data suggest that TGF-beta1 is the major TGF-beta isoform produced by human bone cells in vitro, and that the constitutive secretion of TGF-beta by bone cells does not change with age. Whether constitutive differences in TGF-beta secretion may be a determinant of human bone mass remains to be clarified in further studies.

Adult↗
PubMed1999

Influence of ramipril on the course of plasma thrombomodulin in patients with diabetes mellitus.

BACKGROUND: In diabetic patients endothelial dysfunction is reflected by an increased urinary albumine excretion, which can be reduced by ACE-inhibitors. No data are available showing a endothelial-protective effect by determining a marker reflecting endothelial cell-damage. PATIENTS AND METHODS: The effect of angiotensin converting enzyme inhibitor (ACEI) (ramipril) treatment on the progression of endothelial cell damage,--assessed by measurement of plasma-thrombomodulin (TM),--was investigated in an open, non randomized, prospective pilot study over a period of 18 months in diabetic patients. 87 patients with an urinary albumin concentration (UAC) below 100 mg/l at baseline were included. 46 patients were treated without ACEI and served as a control group, 41 patients were treated with ACEI. Participation in this study did not affect intensity in the treatment of blood glucose, blood pressure or diet. At study entry both groups were comparable with respect to duration of diabetes, diabetic complications, vascular risk factors, body mass index, medications used to treat diabetes, presence of hypertension, glycemic control, tryglycerides, HDL cholesterol, creatinine, UAC and plasma-TM. Age, blood pressure, and total cholesterol were significantly higher in the ACEI group, compared with the control group. RESULTS: After a follow up of 18 months a significant increase in UAC (delta UAC = 10.48 mg/l, p = 0.03) and plasma-TM (delta TM = 3.06 ng/l, p = 0.009) was observed in the control group, while in the ACEI treated group a decrease in albuminuria (delta UAC = -7.44 mg/l, p = 0.01) and plasma-TM (delta TM = -4.78 ng/l, p = 0.001) was seen. Despite a similar approach in hypertension and diabetes control in both groups, UAC and plasma-TM decreased after 18 months only in the ACEI treated group. Treatment with ACEI was the strongest predictor (p = 0.0001) indicating decrease of UAC and plasma-TM (multi regression analysis). CONCLUSION: Plasma-thrombomodulin might be a useful marker for assessing the efficacy of drugs potentially protecting the vessel wall. While the present study was a open, non randomized study, further investigation is necessary to proof the hypothesis in a randomized, placebo-controlled, double-blind study.

Adult↗
PubMed1999

A novel lipoprotein from the hemolymph of the cochineal insect, Dactylopius confusus.

A new type of insect lipoprotein was isolated from the hemolymph of the female cochineal insect Dactylopius confusus. The lipoprotein from the cochineal insect hemolymph was found to have a relative molecular mass of 450 000. It contains 48% lipid, mostly diacylglycerol, phospholipids and hydrocarbons. The protein moiety of the lipoprotein consists of two apoproteins of approximately 25 and 22 kDa, both of which are glycosylated. Both apolipoproteins are also found free in the hemolymph, unassociated with any lipid. Purified cochineal apolipoproteins can combine with Manduca sexta lipophorin, if injected together with adipokinetic hormone into M. sexta. This could indicate that the cochineal lipoprotein can function as a lipid shuttle similar to lipophorins of other insects, and that the cochineal insect apolipoproteins have an overall structure similar to insect apolipophorin-III.

Amino Acid Sequence↗
PubMed1999

Add-back medrogestone does not prevent bone loss in premenopausal women treated with goserelin.

To investigate the effect of medrogestone on bone mineral density (BMD) and bone turnover under conditions of estrogen withdrawal, premenopausal women with endometriosis were treated with goserelin (Zoladex), combined with either placebo (group A, n = 12) or 10 mg medrogestone (Prothil, group B, n = 11) for six months, and followed for an additional six months. Lumbar spine BMD was measured at 0 and 6 month. Markers of bone turnover were serum bone alkaline phosphatase (sBAP) and osteocalcin (sOC) by ELISA, and urinary total pyridinoline (uPYD) and deoxypyridinoline crosslinks (uDPD) by HPLC. Patients in both groups had a similar and significant decrease in BMD after 6 months (4%, p < 0.01). The time course of changes in bone turnover, in contrast, was different in both groups. In group A, crosslink excretion increased from one month onwards, while no changes were seen in group B. In group A, sBAP levels rose during treatment, while in group B, this rise was delayed until treatment was terminated. Additionally, group B showed an initial suppression of sBAP and sOC. In both groups, sOC increased after treatment was discontinued. Medrogestone at 10 mg/d does not prevent lumbar bone loss in premenopausal women under estrogen deprivation. In the medrogestone add back group, the changes in bone turnover are compatible with low turnover bone loss,as ooposed to a state of high turnover seen in the unopposed goserelin group. This effect may be due to glucocorticoid receptor mediated actions of medrogestone on bone.

Adult↗
PubMed1999

Postmenopausal hormone replacement therapy and the vascular wall: mechanisms of 17 beta-estradiol's effects on vascular biology.

17 beta-estradiol (E2) protects against atherosclerosis independent of changes in plasma lipoproteins in a variety of animal models, which is explained by direct effects of E2 on the vascular wall. E2 improves vasomotion by modulation of vasoconstrictor and vasodilator systems through endothelium-dependent and endothelium-independent mechanisms. E2 affects the remodeling of the vascular wall by inhibiting smooth muscle cell proliferation and accelerating reendothelialization of injured blood vessels. E2 modulates the vascular inflammatory response by inhibiting cytokine production, cytokine-induced expression of cell adhesion molecules and platelet aggregation/adhesion. This review focuses on the cellular and molecular mechanisms underlying these vasculoprotective actions of E2. E2 can act through nongenomic stimulation of membrane/intracellular mediators and/or the classical genomic pathway of steroid actions, which is dependent on transcription and protein synthesis. The existence of at least two nuclear estrogen receptor (ER) subtypes alpha and beta and a putative membrane ER present the potential of tissue-specific as well as biologically different E2 actions. Nuclear ERs act as ligand-activated transcription factors and can affect gene regulation by interaction with the classical estrogen response element or other nonreceptor transcription factors. The molecular basis of genomic E2 actions by identifying transcription factors and regulatory elements involved in the induction and inhibition of E2 regulated gene expression is only at the beginning of being understood. The impact of E2-mediated increased NO availability on the hemodynamic and antiatherosclerotic actions of E2 is still a debate of controversy.

Cytokines↗
PubMed1999

[Quantitative gas chromatography-mass spectrometry determination of pentaerythrityl tetranitrate metabolites pentaerythrityl trinitrate, pentaerythrityl dinitrate and pentaerythrityl in human plasma].

Assay methods based on gas chromatography/mass spectroscopy (GC-MS) may be used to measure PE1N (pentaerithrityl mononitrate, CAS 1607-00-7), PE2N (pentaerithrityl dinitrate, CAS 1607-01-8) and intermediate pentaerithrityltrinitrate (PE3N, CAS 1607-17-6) in human plasma. Based on this method a simplified method to quantify the metabolites of PETN (pentaerithrityl tetranitrate, CAS 78-11-5, Pentalong) is described. In the present study a consistent method to extract the metabolites of human plasma and following derivatisation is described. Since PE1N can be quantified up to 150 ng/ml, PE2N and PE3N up to 30 ng/ml in human plasma, a dilution of the plasma samples can be avoided. The mean recovery rate is not so high as in other described methods, and inaccuracy is about 10%. Therefore a calibration range between 0.2-30 ng/ml of PE2N and 1-150 ng/ml of PE1N has to be considered. The described method offers an alternative and applicable option to quantify the PETN-metabolites and elucidate their part as NO-donors.

Biotransformation↗
PubMed1999

The effect of pramlintide (amylin analogue) treatment on bone metabolism and bone density in patients with type 1 diabetes mellitus.

Amylin is a 37-amino-acid peptide related to CGRP and calcitonin. It is co-secreted with insulin from pancreatic beta-cells. Amylin is deficient with type 1 diabetes mellitus. To study the in vivo effects of amylin in humans, diabetic patients are an adequate model of chronic amylin deficiency. We investigated the effect of a 12 months pramlintide therapy (amylin analogue) on bone metabolism in patients with type 1 diabetes mellitus. 23 patients with type 1 diabetes mellitus (age 45.2 +/- 10.3 years, duration of diabetes mellitus 20.7 +/- 9.8 years, 13 male, 10 female) injected themselves 0.1 ml pramlintide, a human amylin analogue, four times per day for a period of 12 months. Bone mineral density measurements of the lumbar spine by dual-energy X-ray absorptiometry (DXA), and biochemical markers of bone metabolism (serum-calcium, PTH, osteocalcin, urinary pyridinium cross-links) were obtained before and one year after starting pramlintide therapy. None of the following parameters changed significantly: bone density, serum calcium, PTH, osteocalcin or pyridinium cross-links. Only osteocalcin decreased from 7.205 ng/ml to 5.825 ng/ml, but this change was not statistically significant. We conclude that a one-year pramlintide therapy does not affect bone density or bone metabolism in patients with type 1 diabetes mellitus without osteopenia (based on the markers used).

Adolescent↗
PubMed1999

Cell specific effects of glucocorticoid treatment on the NF-kappaBp65/IkappaBalpha system in patients with Crohn's disease.

UNLABELLED: BACKGROUND/AIMS/PATIENTS: Glucocorticoid treatment is known to reduce nuclear factor-kappa B (NF-kappaB)p65 binding activity and activation in lamina propria cells of patients with Crohn's disease. However, lamina propria cells of glucocorticoid treated patients did not show increased expression of IkappaBalpha, and the hypothesised upregulation of IkappaBalpha by glucocorticoid treatment has not yet been shown in vivo. To investigate whether cells other than lamina propria localised mononuclear cells contribute to increased IkappaBalpha, resection gut specimens from patients matched for Crohn's disease activity index (CDAI) with or without glucocorticoid treatment were studied, and changes in the NF-kappaB/IkappaBalpha system were determined in the lamina propria as well as in underlying submucosal and endothelial cells. METHODS: Changes in the NF-kappaB/IkappaBalpha system were determined by immunohistochemistry, electrophoretic mobility shift assay, and western blot analysis in resected gut specimens from patients matched for CDAI and van Hees index with or without long term glucocorticoid treatment. RESULTS: Resection gut specimens from patients with Crohn's disease under glucocorticoid treatment had significantly lower nuclear NF-kappaBp65 levels in mononuclear, epithelial, and endothelial cells than samples from CDAI and van Hees index matched patients not having glucocorticoid treatment. Nuclear NF-kappaBp65 showed a strong positive correlation with both the CDAI (r = 1 for both groups) and the van Hees index (r = 0.605 for untreated and r = 0.866 for glucocorticoid treated specimens). Lower nuclear translocation of NF-kappaBp65 in the glucocorticoid treated group was paralleled by higher IkappaBalpha levels in vascular endothelial cells, but not in infiltrating mononuclear cells. CONCLUSION: A comparison of resection gut specimens from untreated and treated CDAI matched patients with Crohn's disease showed downregulation of NF-kappaB binding activity and NF-kappaBp65 expression and cell specific induction of endothelial IkappaBkappa expression in the glucocorticoid treated group. As the two groups showed similar disease activity (CDAI, van Hees index), the activation of the NF-kappaBp65/IkappaBalpha system must be only part of the inflammatory cascade leading to the clinical appearance of Crohn's disease.

Adult↗
PubMed1999

Development of an Immunofluorometric, High-Capacity, Cell-Based Assay for the Measurement of Human Type I and Type II Interferons.

We have developed a cell-based 96-well microtiter plate, high throughput assay for measuring both type I and type II interferon (IFN) activity on human cells. This assay makes use of a previously described IFN-specific reporter stably expressed in human HT 1080 cells. The induction of the reporter by IFN is determined by measuring the IFN-dependent expression of CD2 on the cell surface. The cytokine-induced expression of CD2 occurs within 48 h and is measured using a time-resolved fluorometric immunoassay. The limit of detection for type I IFN is.0.4 IU/ml. Interassay and intraassay coefficients of variation were 1.1% and 1.3% for the medium control (31 IU IFNb1b/ml), respectively. The limit of detection for type II IFN is.8 IU/ml, and the assay coefficients of variation are similar to those determined for type I IFNs. The level of sensitivity for this assay is comparable to other assays commonly used to measure IFN activity on cells. The current assay has an advantage over antiviral and antiproliferative assays, in that there is no requirement for the use of pathogenic virus or for determining viable cell numbers. The current assay is ideally suited for increasing sample screening and high-capacity automation, making it an excellent tool for drug discovery.

Journal Article↗
PubMed1999

Severe osteoporosis in familial Hajdu-Cheney syndrome: progression of acro-osteolysis and osteoporosis during long-term follow-up.

Hajdu-Cheney syndrome is an autosomal dominant inherited osteodysplastic bone disease with the hallmarks of acro-osteolysis, skull deformations, and generalized osteoporosis. Very few patients have been followed long-term with respect to the prognosis of acro-osteolysis and osteoporosis. Here we describe a 39-year-old woman and her 19-year-old daughter who are both affected with the Hajdu-Cheney syndrome. Skeletal lesions were followed in the mother between the ages of 22 and 39 years. The acro-osteolytic lesions progressed markedly and caused shortening of several fingers; some end phalanges had completely disappeared. Severe spinal osteoporosis with serial vertebral fractures was found at the age of 22 years. New vertebral fractures developed until the age of 33 years, but did not progress afterward. High turnover osteoporosis was found in the bone histology of iliac crest biopsies performed at the ages of 22 and 34 years. Bone mineral content (BMC) was strikingly decreased at the age of 34 years (T score -5.1 SD) and did not significantly change during further follow-up. In the daughter, BMC failed to increase between the ages of 12 and 19 years and was also markedly decreased (T score -4.4 SD). This suggests that osteoporosis in Hajdu-Cheney syndrome is related to a low peak bone mass and a high bone turnover, leading to insufficient bone formation compared with the increased bone resorption.

Adult↗
PubMed1999

Novel serum markers of bone resorption: clinical assessment and comparison with established urinary indices.

Although urinary measurements of collagen degradation provide valid estimates of bone resorption, their clinical application is hampered by pronounced analytical and biological variability. Therefore, immunoassays for the determination of such parameters in serum have been developed. In this study, we assessed the performance of three new serum markers of bone turnover, i.e., C-terminal and N-terminal telopeptides of type I collagen (S-CTX and S-NTX) and bone sialoprotein. Results were compared with urinary total pyridinoline, total deoxypyridinoline, and urinary C-terminal telopeptides of type I collagen (U-CTX) and urinary N-terminal telopeptides of type I collagen (U-NTX). The study population included healthy men (n = 27), premenopausal (n = 30) and postmenopausal (n = 31) women, patients with hepatic dysfunction (HF, n = 24), renal failure (RF, n = 30), breast cancer without (BC-, n = 24) and with (BC+, n = 30) bone metastases, primary vertebral osteoporosis (OPO, n = 27), primary hyperparathyroidism (PHPT, n = 16), active Paget's disease of bone (n = 18), multiple myeloma (MM, n = 18), and patients with hypercalcemia of malignancy before and after treatment with pamidronate (HOM, n = 28). Changes in urinary and serum markers were similar in most metabolic bone diseases. However, differentiation between healthy controls and OPO, or PHPT, was improved by the serum markers. In MM, all serum and urinary markers were elevated (p < 0. 05 vs. controls). In BC+, skeletal involvement was reflected by significant increments in all indices (p < 0.01 vs. BC-), except U-CTX and S-CTX. In HOM, pamidronate-induced changes in biomarkers were most pronounced for U-CTX and S-CTX and S-NTX. HF and RF were associated with elevated levels of all serum markers (p < 0.05 vs. controls). In conclusion, measurements in serum reflect bone resorption to the same extent as the urinary indices. Since serum markers circumvent some of the limitations of urinary measurements, their use potentially improves the assessment of skeletal disorders.

Adult↗