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  • Author: Wolfgang Rascher x
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Jörg Dötsch, Wolfgang Rascher and Udo Meißner

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Jörg Dötsch, Wolfgang Rascher and Udo Meißner

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Jörg Dötsch, Ina Knerr, Wolfgang Rascher and Udo Meißner

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Udo Meißner, Robert Spranger, Manfed Lehner, Ida Allabauer, Wolfgang Rascher and Jörg Dötsch

Objective: The ob-gene product, leptin, is an important regulator of placental and fetal development during pregnancy. Leptin, being induced by hypoxia in the placenta, is a known pro-apoptotic molecule in adipose tissue but is also known to inhibit apoptosis in other tissues like neuroblastoma cells. Based on these findings, we investigated if leptin has a pro- or anti-apoptotic effect on a trophoblastic cell line (JAr cells) in the presence or absence of oxygen.

Methods and results: Measurement of leptin in the supernatant by using ELISA showed hypoxia-induced leptin production in JAr cells in vitro. This could be confirmed by a leptin-specific RT-PCR. By analyzing leptin and/or hypoxia exposed cells with FACS cytometry we found that JAr cells can cope with hypoxia down to oxygen tensions of 1%. At this level, only a small number of cells underwent apoptosis. Interestingly, leptin added to the culture medium in high concentrations was not able to interfere with the rate of proliferation or apoptosis in these cells independent of the oxygen tension. Finally, an anti-caspase-3 and anti-caspase-9 Western blot was performed. Again, no difference in the expression of caspase-3 and -9 under the conditions tested was seen.

Conclusions: These results show that leptin, produced by placental cells after hypoxia in vitro, has no influence on the rate of proliferation of these cells. Furthermore, it does not influence apoptotic pathways in the trophoblastic cell line tested under hypoxic and non-hypoxic conditions.

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Michael Schroth, Christian Plank, Manfred Rauh, Helmuth-Günther Dörr, Wolfgang Rascher and Jörg Dötsch

Objective: The conversion of cortisol (F) to cortisone (E) is catalyzed by 11beta-hydroxysteroid dehydrogenase type 2 (11β-HSD2). Children suffering from chronic renal failure (CRF) have a decreased activity of 11β-HSD2 contributing to increased arterial blood pressure. The objective was to investigate whether a normal conversion of F to E is achieved after renal transplantation (TX) in children.

Methods: Fifteen children with CRF, 17 children with steroid-free immunosuppression after TX, and 18 healthy controls (CO) were enrolled. The activity of 11β-HSD2 in plasma was calculated using the ratio of F/E determined by tandem mass spectrometry, the ratio of tetrahydrocortisol (THF) +5α-tetrahydrocortisol (5αTHF) in urine determined by gas chromatography/mass spectrometry, and the ratio of (THF +5αTHF)/tetrahydrocortisone (THE) in urine determined by tandem mass spectrometry.

Results: The F/E ratio (mean ± s.d./s.e.m.) was significantly higher in CRF and TX (5.6 ± 1.9/0.6, 7.12 ± 3.1/0.9) than in CO (1.18 ± 0.2/0.03, P < 0.0001) groups. The (THF + 5αTHF)/THE ratio in CRF (1.19 ± 1.1/0.5) and TX (1.19 ± 0.1/0.5) groups was significantly higher than in controls (0.21 ± 0.05/0.18, P < 0.0001). Positive correlations between plasma and urinary ratios (P = 0.0004. R2 = 0.73 in CRF, P = 0.0013, R2 = 0.56 in TX, P < 0.0001, R2 = 0.66 in CO) were found, whereas significant correlations between F/E or (THF + 5αTHF)/THE ratios and blood pressure, the number of antihypertensive drugs taken or creatinine clearance could not be found.

Conclusions: In all children with chronic renal failure plasma and urinary cortisol/cortisone ratios are elevated and do not return to normal levels after renal allograft transplantation. This suggests that renal transplantation does not normalize 11β-HSD2 activity.

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Andreas Hoeflich, Yi Yang, Wolfgang Rascher, Werner F Blum, Stefan Huber, Gabriele Koepf, Helmut J Kolb and Wieland Kiess

Hoeflich A, Yang Y, Rascher W, Blum WF, Huber S, Koepf G, Kolb HJ, Kiess W. Coordinate expression of insulin-like growth factor II (IGF-II) and IGF-II/mannose-6-phosphate receptor mRNA and stable expression of IGF-I receptor mRNA during differentiation of human colon carcinoma cells (Caco-2). Eur J Endocrinol 1996;135:49–59. ISSN 0804–4643

Insulin-like growth factor II (IGF-II) has been implicated in the differentiation of skeletal muscle cells. In this study the putative role of IGF-II in epithelial cell differentiation was investigated. The expression of IGF-II, IGF-1 receptor and IGF-II/mannose-6-phosphate receptor (IGF-II/M6P receptor) mRNA during spontaneous differentiation of the colon carcinoma cell line Caco-2 was measured. In addition, differentiation of Caco-2 cells during the cell culture period (days 1–21 in culture) was studied in parallel using morphological (light and scanning electron microscopy) and biochemical markers of growth (DNA, RNA and protein content, and β-actin mRNA and glyceraldehyde phosphate dehydrogenase mRNA expression) and differentiation (alkaline phosphatase activity, carcinoembryonic antigen content). A putative correlation between the markers of growth and differentiation and IGF gene expression was studied using linear regression analysis. Expression of IGF-II mRNA and IGF-II/M6P receptor mRNA correlated significantly with the progress of differentiation, while the IGF-I receptor was stably expressed throughout the culture period and exhibited a crucial role for the survival of Caco-2 cells, as shown by blocking experiments employing the monoclonal anti-IGF-I receptor antibody alpha-IR3. We hypothesize that: IGF-II mRNA and IGF-II/M6P receptor mRNA are expressed in a coordinate fashion during the differentiation of Caco-2 cells; coordinate expression of IGF-II and of IGF-II/M6P receptor mRNA might point to a role for IGF-II as a growth stimulant and for the IGF-II/M6P receptor for a regulator of IGF-II bioavailability in differentiating cells; alternatively, high IGF-II/M6P receptor mRNA and protein expression in differentiated cells but low IGF-II binding to the IGF-II/M6P receptor point to an important intracellular role of this receptor type in differentiated colon epithelial cells; the IGF-I receptor mRNA is stably expressed during the differentiation process of Caco-2 cells; the IGF-I receptor protein seems to be a prerequisite for the survival of Caco-2 cells.

W Kiess, Children's Hospital, Justus Liebig University, Feulgenstr. 12, D-35385 Giessen, Germany

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Thomas M K Völkl, Diemud Simm, Antje Körner, Wolfgang Rascher, Wieland Kiess, Jürgen Kratzsch and Helmuth G Dörr

Objective

Congenital adrenal hyperplasia (CAH) patients are at a higher risk to develop obesity. The role of leptin in CAH is still controversial. Our study aimed to evaluate serum levels of leptin, the soluble leptin receptor (sOB-R), and the sOB-R: leptin molar ratios in a cohort of CAH children and adolescents, and their associations with clinical and metabolic parameters.

Methods

We studied 51 CAH patients, aged 5.6–19.6 years (median 11.8, n=30 females) cross-sectionally. All patients had genetically proven CAH and received standard steroid substitution therapy. Blood specimens were taken after overnight fasting between 0800 and 1000 h. For the analyses of leptin and sOB-R, matched pairs were built with healthy Caucasian patients for sex, Tanner stage (TS), chronologic age (CA), and body mass index (BMI).

Results

BMI and SDS were significantly elevated compared with the reference population. Leptin levels were not different between matched pairs, whereas sOB-R levels were significantly lower in CAH. Consequently, the sOB-R: leptin molar ratios were significantly decreased in CAH. Correlation analyses in CAH patients revealed significant relationship between leptin and CA, TS, BMI, and homeostasis model assessment of insulin resistance. Similar results were obtained for the matched control group. For sOB-R, we found no significant correlation for CA, TS, or BMI in CAH, but we did in the controls. There were significant correlations for androgens within the CAH group. Additional analyses revealed no correlation with steroid medication or metabolic control.

Conclusions

Our data show that an altered leptin axis with normal serum leptin concentrations but decreased sOB-R serum levels may contribute to the increased risk of overweight and obesity in CAH.