Jürgen Merke

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Because 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) has been shown to play roles in both proliferation and differentiation of novel target cells, the potential expression of 1,25(OH)2D3 receptor (VDR) activity was investigated in cultured bovine aortic endothelial cells (BAEC). Receptor binding assays performed on nuclear extracts of BAEC revealed a single class(More)
Parathyroid cell proliferation and parathyroid hyperplasia are features of renal secondary hyperparathyroidism. Since parathyroids have recently been recognized as an important target for 1,25(OH)2D3, the effects of administration of variable doses of 1,25(OH)2D3 on ex vivo radiothymidine incorporation in the parathyroid glands, on parathyroid cell mitoses,(More)
We developed an immunohistochemical method for visualization of vitamin D (VDR) and estrogen receptors (ER) in cryostat sections, using monoclonal antibodies (MAb) to the vitamin D receptor and estrogen receptor, respectively. This method is based on an avidin-biotin labeling technique (LAB). To establish a reliable and sensitive method which can be used(More)
1,25(OH)2D3 receptors were studied in whole testes, Sertoli cells, seminiferous tubules, Leydig cells and spermatogonia of adult NMRI mice and SD rats. Specific reversible high affinity binding (KD 1.4 x 10(-10)M; Nmax 72 fmol/mg protein) by a 3.5 S macromolecule was demonstrated in whole testes, Sertoli cells and seminiferous tubules. With identical(More)
OBJECTIVE Dyslipidemia in patients with type 2 diabetes is characterized by elevated triglyceride levels, decreased high-density lipoprotein (HDL) cholesterol, and a predominance of small dense low-density lipoprotein (LDL) particles. Also, patients suffer from β-cell dysfunction, chronic systemic inflammation, increased hormonal visceral adipose tissue(More)
Abnormalities of calcium metabolism and of its two principal regulating hormones, parathyroid hormone and 1,25-dihydroxyvitamin D3 (calcitriol), have been reported in the spontaneously hypertensive rat (SHR). Reports of abnormal calcitriol metabolism in the SHR by several groups have not provided measurements of tissue calcitriol receptors. Similarly, few(More)
In parathyroids of uraemic patients or animals, decreased specific binding of 1,25(OH)2D3 has been observed and implicated in the genesis of secondary hyperparathyroidism of renal failure. We re-examined binding of 1,25(OH)2D3 using chromatin preparations for receptor characterization which differed from previous studies (a) by inclusion of protease(More)
Clinical evidence points to disturbed calcium metabolism in lead (Pb) intoxication. To further clarify the mechanisms involved, serum levels of 1,25(OH)2D3, receptors for 1,25(OH)2D3 as well as size and ultrastructure of parathyroid glands were examined in Wistar Kyoto rats exposed to 1% lead (Pb) acetate in drinking water for 10 weeks (short-term study) or(More)
In Sprague Dawley rats, six days after subtotal nephrectomy, serum 1,25(OH)2D3 concentration was diminished (59.8 +/- 17.5 pg/ml vs. 121 +/- 48; P less than 0.01). Despite low circulating 1,25(OH)2D3 levels, maximal specific binding capacity for 1,25(OH)2D3 in parathyroid glands was diminished (Nmax 87.5 fmol/mg protein and 3.52 fmol/mg DNA vs. 143 fmol/mg(More)
In up to six different sides along the body axis during tilting manoeuvres, volume shifts into or out off superficial tissues were followed with a newly developed miniature plethysmograph. It was possible to localized a region where no or only minor volume changes during the tilt table experiments occurred. This region is identical with the Hydrostatic(More)