Chondrodysplasia Grebe type (CGT) is an autosomal recessive disorder characterized by severe limb shortening and dysmorphogenesis. We have identified a causative point mutation in the gene encoding the bone morphogenetic protein (BMP)-like molecule, cartilage-derived morphogenetic protein-1 (CDMP-1). The mutation substitutes a tyrosine for the first of seven highly conserved cysteine residues in the mature active domain of the protein. We demonstrate that the mutation results in a protein that is not secreted and is inactive in vitro. It produces a dominant negative effect by preventing the secretion of other, related BMP family members. We present evidence that this may occur through the formation of heterodimers. The mutation and its proposed mechanism of action provide the first human genetic indication that composite expression patterns of different BMPs dictate limb and digit morphogenesis.

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Disseminated malignancy is the major cause of prostate cancer-related mortality. Circulating tumor cells (CTCs) are essential for the establishment of metastasis. Various contemporary and molecular methods using prostate-specific biomarkers have been applied to detect extraprostatic disease that is undetectable by conventional imaging techniques, assessing the risk for disease recurrence after therapy of curative intent. However, the clinical relevance of CTC detection is still controversial. We review current literature regarding molecular methods used for the detection of CTCs in the peripheral blood and bone marrow biopsies of patients with prostate cancer, and we discuss the methodological pitfalls that influence the clinical significance of molecular staging.

We report the isolation and characterization of RK-1, a novel peptide found in the kidney. RK-1 is related to the corticostatin/defensins and has the sequence MPC-SCKKYCDPWEVIDGSCGLFNSKYICCREK but differs from the very cationic corticostatins/defensins in having only one arginine and a calculated charge at pH 7 of ؉1. Like some myeloid corticostatin/defensins RK-1 inhibits the growth of Escherichia coli. Since corticostatin/defensins effect ion flux in responsive epithelia we used volume changes in villus enterocytes as a model system to study the effects of RK-1 on ion channels in epithelial cells. At concentrations 10 ؊9 M RK-1 decreased enterocyte volume in a dose-dependent manner through a pathway that requires extracellular calcium and is inhibited by niguldipine, a dihydropyridine-sensitive "L"-type Ca 2؉ -channel blocker. In other assay systems for corticostatin/defensins, such as the inhibition of adrenocorticotropin-stimulated steroidogenesis, or cell lysis, RK-1 was inactive or only weakly active. These results demonstrate the existence of a novel system of biologically active peptides in the kidney represented by RK-1 which is antimicrobial and can activate epithelial ion channels in vitro.