Biomedical subjects

E Baur

Publications and source records attributed to E Baur.

At least 19 recordsLinked to original sources

PubMed2001

Effects of insulin-like growth factor-1 on retinal endothelial cell glucose transport and proliferation.

Insulin-like growth factor-1 (IGF-1) plays important roles in the developing and mature retina and in pathological states characterized by retinal neovascularization, such as diabetic retinopathy. The effects of IGF-1 on glucose transport and proliferation and the signal transduction pathways underlying these effects were studied in a primary bovine retinal endothelial cell (BREC) culture model. IGF-1 stimulated uptake of the glucose analog 2-deoxyglucose in a dose-dependent manner, with a maximal uptake at 25 ng/mL (3.3 nM) after 24 h. Increased transport occurred in the absence of an increase in total cellular GLUT1 transcript or protein. IGF-1 stimulated activity of both protein kinase C (PKC) and phosphatidylinositol-3 kinase (PI3 kinase), and both pathways were required for IGF-1-mediated BREC glucose transport and thymidine incorporation. Use of a selective inhibitor of the beta isoform of PKC, LY379196, revealed that IGF-1 stimulation of glucose transport was mediated by PKC-beta; however, inhibition of PKC-beta had no effect on BREC proliferation. Taken together, these data suggest that the actions of IGF-1 in retinal endothelial cells couple proliferation with delivery of glucose, an essential metabolic substrate. The present studies extend our general understanding of the effects of IGF-1 on vital cellular activities within the retina in normal physiology and in pathological states such as diabetic retinopathy.

3-O-Methylglucose↗

PubMed1999

Patients with preeclampsia develop agonistic autoantibodies against the angiotensin AT1 receptor.

Immune mechanisms and the renin-angiotensin system are implicated in preeclampsia. We investigated 25 preeclamptic patients and compared them with 12 normotensive pregnant women and 10 pregnant patients with essential hypertension. Antibodies were detected by the chronotropic responses to AT1 receptor-mediated stimulation of cultured neonatal rat cardiomyocytes coupled with receptor-specific antagonists. Immunoglobulin from all preeclamptic patients stimulated the AT1 receptor, whereas immunoglobulin from controls had no effect. The increased autoimmune activity decreased after delivery. Affinity-column purification and anti-human IgG and IgM antibody exposure implicated an IgG antibody directed at the AT1 receptor. Peptides corresponding to sites on the AT1 receptor's second extracellular loop abolished the stimulatory effect. Western blotting with purified patient IgG and a commercially obtained AT1 receptor antibody produced bands of identical molecular weight. Furthermore, confocal microscopy of vascular smooth muscle cells showed colocalization of purified patient IgG and AT1 receptor antibody. The protein kinase C (PKC) inhibitor calphostin C prevented the stimulatory effect. Our results suggest that preeclamptic patients develop stimulatory autoantibodies against the second extracellular AT1 receptor loop. The effect appears to be PKC-mediated. These novel autoantibodies may participate in the angiotensin II-induced vascular lesions in these patients.

Amino Acid Sequence↗

PubMed1995

High glucose concentrations and protein kinase C isoforms in vascular smooth muscle cells.

High extracellular glucose activates protein kinase C (PKC), a family of kinases vital to intracellular signaling. However, which PKC isoforms are involved and where in the cell they operate is unclear. We tested the hypothesis that only those PKC isoforms binding to diacylglycerol (DAG) are activated by high glucose. We also reasoned that the isoforms would translocate to different parts of the cell, where they presumably serve different functions. The PKC isoforms alpha, beta, delta, epsilon, and zeta were studied. Twenty mM glucose caused an increase in total PKC activity at six hours, which was maintained at 24 hours. High glucose decreased the angiotensin II-induced calcium signal. This effect was reversed by preincubating the cells with the PKC inhibitor staurosporine. Glucose induced a translocation of all PKC isoforms except PKC zeta by Western blot. Confocal microscopy showed that PKC alpha, beta, and epsilon were translocated into the nucleus. PKC delta showed strong association with cytoskeletal structures. The effects were sustained at 24 hours for PKC isoform beta and to a lesser extent for PKC delta and epsilon, but not for PKC alpha. Thus, PKC isoforms differ in their propensity to be activated by high glucose. Those isoforms binding to DAG are activated. Both cytoskeletal and nuclear signaling may be involved.

Alkaloids↗

PubMed1990

[Anthracosilicosis changes in abdominal lymph nodes in miners].

Ten retroperitoneal lymph node stations obtained from 100 decreased miners exposed to coal dust in the Ruhr district of Germany were submitted to a morphological and morphometrical investigation. In 87% of the cases, dust depositions were detected in at least one of the retroperitoneal lymph nodes. Up to 21% of the lymph nodes revealed dust-induced granulomatous lesions that extended from small, highly cellular dust granulomas to sclerohyaline nodules. The uniform distribution of iron-containing pigments in the lymph nodes argues in favour of an exogenous source. In individual cases, despite relatively small silicotic lesions in the lungs, depositions of dust were detected in the retroperitoneum. This suggest a physiological significance of existing diaphragmatic lymph vessel connections. A comparable distribution of lymph node metastases in 15 patients with malignant tumours of the lungs supports this view. For this reason, differentiated prognostically informative staging schemas of carcinomas of the lungs should therefore also take into account the retroperitoneal lymph node stations.

Adult↗

PubMed1980