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Biomedical subjects

S M Baumgartner-Parzer

Publications and source records attributed to S M Baumgartner-Parzer.

11 recordsLinked to original sources
PubMed2001

The endothelium as a metabolic and endocrine organ: its relation with insulin resistance.

The vascular endothelium, building the inner layer of capillaries and blood vessels of all sorts, represents a highly active metabolic and endocrine organ producing a multitude of different molecules, including vasoactive peptide hormones, growth factors, coagulation factors and adhesion molecules. In addition, it expresses many of the respective endocrine, paracrine and cytokine/growth factor receptors. It thereby regulates the delicate balance between vasoconstriction and vasodilation, between coagulation and fibrinolysis, proliferation and apoptosis, as well as between transient adhesion and diapedesis of blood borne leukocytes. This minireview addresses the potential interactions of these important functions in the states of diabetes and of insulin resistance including obesity, hypertension and dyslipidaemia, all of which characterized by endothelial dysfunction.

Animals↗
PubMed2001

Mutational spectrum of the steroid 21-hydroxylase gene in Austria: identification of a novel missense mutation.

This study attempted an analysis of the mutational spectrum of 21-hydroxylase deficiency in 79 unrelated Austrian patients with classical and nonclassical forms of congenital adrenal hyperplasia and their respective 112 family members. Apparent large gene deletions/conversions were present in 31% of the 158 unrelated congenital adrenal hyperplasia alleles, whereas the most frequent point mutations were intron 2 splice (22.8%), I172N (15.8%), V281L (12%), and P30L (7.6%), in line with the frequencies reported for other countries. In 5 of the 12 congenital adrenal hyperplasia alleles carrying a P30L mutation the aberration is based on a single base substitution, whereas the remaining 7 represent part of a CYP21B conversion (1 allele) or CYP21B/21A hybrid gene (6 alleles), the latter characterized by a junction site before intron 2 as indicated by Southern blot, PCR, and sequence analyses. Previously described mutations were not present in 1.2% of unrelated congenital adrenal hyperplasia alleles, including one female patient presenting with severe genital virilization. Sequence analysis of the complete functional 21-hydroxylase gene revealed an as yet undescribed mutation in exon 10-Arg(426)His, which has not yet been described to represent a common pseudogene sequence. In vitro expression experiments showed the Arg(426)His mutant to exhibit only low enzyme activity toward the natural substrate 17-hydroxyprogesterone corresponding to the degree of disease manifestation in the patient in whom it was found.

Adrenal Hyperplasia, Congenital↗
PubMed2000

Levamisole induced apoptosis in cultured vascular endothelial cells.

To better understand the anticancer activity of Levamisole (LMS), which serves as an adjuvant in colon cancer therapy in combination with 5-Fluorouracil, this study analyses LMS' ability to induce apoptosis and growth arrest in cultured human micro- and macrovascular endothelial cells (ECs) and fibroblasts. Cells exposed (24 h) to Levamisole (range: 0.5 - 2 mmol l(-1)) alone or in combination with antioxidants (10 mmol l(-1) glutathione or 5 mmol l(-1) N-Acetylcysteine or 0.1 mmol l(-1) Tocopherol) were evaluated for apoptosis ((3)H-thymidine assays, in situ staining), mRNA/protein expression (Northern/Western blot), and proliferation ((3)H-thymidine incorporation). Levamisole dose-dependently increased apoptosis in ECs to 230% (HUVECs-human umbilical vein ECs), 525% (adult human venous ECs) and 600% (human uterine microvascular ECs) but not in fibroblasts compared to control cells (set as 100%). Levamisole increased in ECs integrin-dependent matrix adhesion, inhibited proliferation (-70%), reduced expression of survival factors such as clusterin (-30%), endothelin-1 (-43%), bcl-2 (-34%), endothelial NO-synthase (-32%) and pRb (Retinoblastoma protein: -89%), and increased that of growth arrest/death signals such as p21 (+73%) and bak (+50%). LMS (2 mmol l(-1))-induced apoptosis was inhibited by glutathione (-50%) and N-Acetylcysteine (-36%), which also counteracted reduction by Levamisole of pRb expression, suggesting reactive oxygen species and pRb play a role in these processes. The ability of LMS to selectively induce apoptosis and growth arrest in endothelial cells potentially hints at vascular targeting to contribute to Levamisole's anticancer activity.

Acetylcysteine↗
PubMed1998

Determination of plasma ET-1 by RIA--risks and limitations.

Plasma concentrations of the vasoconstrictor peptide endothelin-1 (ET-1) were determined in nonobese healthy subjects as well as in unspecified patients using three different commercially available radioimmunoassays (RIAs) and the respective recommended prepurification procedures. Depending on the antibody and extraction procedure applied different ET-1 concentrations were measured in identical plasma samples. Thus, this study clearly documents that ET-1 concentrations measured in plasma samples represent apparent concentrations which have to be interpreted with caution.

Endothelin-1↗
PubMed1997

Glycemia and regulation of endothelial adhesion molecules.

Hyperglycemia is one of the most prominent factors associated with diabetic vascular disease, the development of which is initated by functional and morphological alterations of the endothelium. The review summarizes several issues of glycemia and advanced glycation end products induced changes concerning soluble as well as cell bound endothelial adhesion molecules, and further addresses the aspect of apoptosis in the light of diabetic vascular complications.

Apoptosis↗
PubMed1997

Increase by tri-iodothyronine of endothelin-1, fibronectin and von Willebrand factor in cultured endothelial cells.

Hyperthyroidism is associated with elevated plasma levels of endothelium-derived proteins such as von Willebrand factor (vWF), fibronectin (FN) and endothelin-1 (ET-1). This study was designed to characterize the mechanisms involved in this phenomenon at the cellular level. vWF, FN and ET-1 secretion and mRNA expression were measured in human umbilical vein endothelial cells (HUVECs) exposed to tri-iodothyronine (T3) for 13 +/- 1 days, using ELISA, Western blot, RIA and Northern blot analysis respectively. Exposure of HUVECs to T3 significantly increased vWF secretion (50 ng T3/ml: 117 +/- 5%, P < 0.01; 100 ng T3/ml: 127 +/- 26%, P < 0.01) as well as vWF mRNA expression (50 ng/ml: 116 +/- 13%, P < 0.001; 100 ng/ml: 136 +/- 30%, P < 0.002) (results are means +/- S.D. analysed by the Wilcoxon signed rank test). FN secretion was significantly affected by 50 (145 +/- 42% of control, P < 0.05) and 100 (116.8 +/- 16% of control, P < 0.05) ng T3/ml, and FN mRNA expression by 50 ng T3/ml (123 +/- 20%, P < 0.05). Long-term incubation with T3 increased both ET-1 secretion (25 ng/ml: 124 +/- 25%, P < 0.001; 50 ng/ml: 165 +/- 53%, P < 0.05; 100 ng/ml: 116 +/- 17%, P < 0.05) and prepro-ET-1 mRNA expression (25 ng/ml: 112 +/- 16%, P < 0.05; 50 ng/ml: 134 +/- 43%, P < 0.02; 100 ng/ml: 120 +/- 20%, P < 0.02). Protein kinase C (PKC) isoforms epsilon and beta II were not significantly affected by T3, whereas PKC alpha was increased in whole cell lysates and in membrane fractions of cells incubated with 100 but not 50 ng T3/ml. Prepro-ET-1 mRNA stability, cell numbers and proliferation, measured by [3H]thymidine assays, remained unaffected in HUVECs after exposure to T3. These data indicate thyroid hormone-induced upregulation of mRNA expression and protein synthesis of vWF, FN and ET-1, by PKC alpha-, beta II- and epsilon-independent pathways, explaining, at least in part, increased plasma concentrations of endothelial proteins and peptides in the hyperthyroid state.

Blotting, Northern↗
PubMed1996

[Apoptosis--programmed cell death].

Apoptosis or programmed cell death is the physiologic, natural form of cell death, exhibiting characteristic morphological and biochemical features. Apoptosis occurs upon developmental processes and represents an important defense mechanism. Defective apoptosis can result in a variety of diseases. Rapidly growing knowledge upon this mode of cell death, especially the identification of genes involved in the regulation of apoptosis raise the hope for new therapies in the treatment of cancer, autoimmune and neurodegenerative disorders, as well as viral infections.

Animals↗
PubMed1995

Modulation by high glucose of adhesion molecule expression in cultured endothelial cells.

We evaluated the influence of high ambient glucose on cellular expression of adhesion molecules, known to mediate endothelial interaction of leucocytes and monocytes. Paired cultures of individual isolates of human umbilical vein endothelial cells (HUVECs) were studied by fluorescence activated cell sorter analysis after exposure to 30 vs 5 mmol/l glucose. Incubation of HUVECs for 24h in 30 mmol/l glucose increased ICAM-1 (intercellular adhesion molecule-1; 116.4 +/- 16.9% of control, p < or = 0.05), but not PECAM (platelet endothelial cell adhesion molecule) expression, compared to cultures kept in 5 mmol/l glucose. Long-term exposure (13 +/- 1 days) of HUVECs to 30 mmol/l glucose increased expression of ICAM-1 to 122.5 +/- 32.2% (p < 0.002) and reduced that of PECAM to 86.9 +/- 21.3% vs the respective control culture in 5 mmol/l glucose (p < 0.02). Stimulation of confluent HUVECs, kept in 30 vs 5 mmol/l glucose for 13 +/- 1 days, with 20 U/ml interleukin-1 for 24 h (ICAM-1) and 4 h (endothelial leukocyte adhesion molecule 1) resulted in reduced ICAM-1 (84.8 +/- 27.0%, p < 0.05) and endothelial leukocyte adhesion molecule-1 (87.6 +/- 22.4%, p < 0.05) expression vs control cells, while that of PECAM (t:24 h) and vascular cell adhesion molecule-1 (t: 16 h) remained unchanged. In conclusion, it appears that differences in expression of adhesion molecules on HUVECs in response to high glucose reflects endothelial glucose toxicity, which may also induce endothelial dysfunction in diabetes.

Cell Adhesion Molecules↗
PubMed1995

Possible clinical effects of the interaction of hemodialysis membranes with adhesion proteins.

In this study data obtained in an in vitro hemodialysis model are related to various parameters measured in patients' plasma during hemodialysis in a clinical crossover study. In vitro, blood from healthy volunteers was dialyzed under standardized conditions using the capillaries Fresenius MTS C (Cuprophane) and Hospal AN 69 (Polyacrylonitrile). Following dialysis, surface bound proteins were eluted with saline, 1 M Tris and 2% SDS, and analyzed by immunoblotting. Depending on the capillary, different protein patterns could be identified in the eluates. Intact forms of adhesion proteins were predominantly (fibrinogen) or exclusively (vitronectin) found in PA eluates. In contrast, low molecular weight products of fibrinogen as well as high molecular weight components containing antithrombin III (AT III) were present in CP eluates. Their presence may reflect fibrinolytic and procoagulatory activity during dialysis with CP capillaries. A microscopic investigation of CP membranes demonstrated fibrin lined platelet conglomerates. In the plasmas of patients dialyzed with CP capillaries high D-Dimer concentrations were found. We also noticed that during dialysis with PA membranes less heparin was consumed than during dialysis with CP membranes. Our study showed a good correlation of the observations in the vitro system and the measurements in patient samples.

Adsorption↗
PubMed1995

High-glucose--triggered apoptosis in cultured endothelial cells.

High ambient glucose concentration, linked to vascular complications in diabetes in vivo, modulates mRNA expression of fibronectin, collagen, tissue-type plasminogen activator, and plasminogen activator inhibitor and induces delayed replication and excess cell death in cultured vascular endothelial cells. To determine the role of high ambient glucose (30 mmol/l) in apoptosis, paired cultures of individual isolates of human umbilical vein endothelial cells (HUVECs) were exposed to both high (30 mmol/l) and low (5 mmol/l) concentrations of glucose for short-term (24, 48, and 72 h) and long-term (13 +/- 1 days) experiments. Incubation of HUVECs with high glucose for > 48 h increased DNA fragmentation (13.7 +/- 6.5% of total DNA, mean +/- SD) versus cultures kept in 5 mmol/l glucose (10.9 +/- 5.6%, P < 0.005), as measured by [3H]thymidine assays. Data were confirmed by apoptosis-specific fluorescence-activated cell sorter analysis of confluent HUVEC cultures, which displayed after long-term exposure to 30 mmol/l glucose a 1.5-fold higher prevalence of apoptosis than control cultures exposed to 5 mmol/l glucose (P < 0.005). In contrast, no increase in DNA fragmentation in response to 30 mmol/l glucose was seen for standardized cell lines (K 562, P 815, YT) and fibroblasts. Expression of clusterin mRNA, originally reported to be a molecular marker of apoptosis, was only slightly affected by short-term (24-h) high-glucose exposure but was significantly reduced after long-term incubation in 30 mmol/l glucose (82.2 +/- 13.8% of control) versus 5 mmol/l glucose, which questions the role of clusterin gene expression as a marker of apoptosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Apoptosis↗