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Organotin as monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) compounds are used as fungicides and anti-fouling compounds; small amounts are added to the new European Euro bills. Little is known about the toxicological profile of these compounds uptake and metabolism. We, therefore, studied the cytotoxicity of these agents in different cell lines, i.e., liver HepG2, renal LLCMK2 and ocular CEC cells. As a measure of cell growth and death, the neutral red assay and the release of LDH into the medium were used. IC50 values for growth inhibition by TBT were calculated as 160 nM in LLC-MK2, 150 nM in HepG2 and 180 nM in CEC cells; for DBT the corresponding values were higher, i.e., 500 nM DBT for LLC-MK2 cells, 300 nM for HepG2 cells and 220 nM for CE cells. ED50 values for LDH release indicating disturbances of the outer cell membrane was > 250 nM for TBT and > 350 nM for DBT in all cells. MBT was not toxic in concentrations up to 500 nM. Electron microscopic studies of cells treated with 300 nM tributyltin indicated severe mitochondrial damage with much less effect seen in other cell structures. We conclude that no differences exist between different cell lines that may serve as examples of tissues relevant for organotin exposure (eye), metabolism (liver) and specific metalloid damage (kidney). Growth inhibition was affected at organotin concentrations between 150 and 500 nM. This concentration is approximately 70-200 fold higher than values estimated in environmental samples.

The vascular anatomy of the growth plate is not yet fully understood with some reports on transphyseal vessels the role of which remains unclear. Further, the development of bone bridges and axial and longitudinal deformities cannot be completely explained with present knowledge. Material and Methods: Under general anesthesia, a Salter-Harris-II-fracture was created at the medial aspect of the proximal tibia in 16 immature sheep and stabilized by an external fixateur. The perfusion study in ten sheep used Mercox® and corrosion casts were obtained. The histological analysis of the remaining six sheep was made by conventional stains and immunohistochemistry against bromodeoxyuridine (BrdU) to evaluate the cell proliferation rate. The observation time was 0, 1, 2, 4, 6, and 12 weeks. Results: The healing process of growth plate fractures followed a regular pattern. After posttraumatic depression of any proliferation up to 1 week, a rich neovascularization took place seen in the vascular casts and the histological sections. This phenomenon was dominant until the 6th week after injury. Then, the hypervascularity and the proliferation rate returned to normal. The temporary hypervascularity was closely associated with the increased proliferation rate demonstrated by immunohistochemistry. Conclusions: Healing growth plate fractures is dominated by the vascular response to the injury. The temporary hypervascularity 1–6 weeks after the fracture leads to a higher proliferation rate of the chondrocytes in the proliferative zone. These results may be one explanation for the development of posttraumatic longitudinal and angular deformities as a result of temporary hypervascularity.

Vascular endothelial growth factor (VEGF)—also known as vascular permeability factor—has been implicated in the regulation of blood vessel formation, i.e., vasculogenesis and angiogenesis. High amounts of VEGF mRNA and protein have been detected during embryonic and tumor angiogenesis, but it remained unclear whether the level of VEGF correlated with the extent of vascularization in a given organ or tissue. We examined the role of VEGF and the high affinity, signal-transducing VEGF receptor-2 (flk-1) in the avian embryo. In a gain of function transgene-like approach the retroviral expression vector RCAS was used to increase the level of quail VEGF during critical periods of avian limb bud growth and morphogenesis. In contrast to basic fibroblast growth factor, which recently was demonstrated to induce morphogenetic alterations when overexpressed in this system, overexpression of VEGF in the limb bud exclusively resulted in hypervascularization as reflected by an increase in vascular density. However, cartilage expressing the construct was not vascularized prematurely. Thus hypervascularization was probably due to the augmentation of the VEGF signaling mechanism in a permissive environment. In addition to hypervascularization, vascular permeability was dramatically increased, leading to local and in some cases to general edema. This is the first indication of a link between the functions of VEGF as a vascular growth factor and as a permeability factor. VEGF receptor-2 (flk-1) was found to be upregulated only in those areas where VEGF was overexpressed. This implies a positive feedback system of the VEGF receptor on its own synthesis and would provide a basis for a paracrine system in which ligand concentration is critical for the extent of tissue vascularization. Our results show that the VEGF/VEGF-receptor system is specific and sufficient for the formation of new blood vessels. They also have implications for somatic gene therapy of diseases which are characterized by a lack of blood vessels such as chronic ischemic diseases of heart and brain.

Summary An antiserum against bovine parathyroid hormone was raised and applied for demonstration of parathormone-containing cells. Parathyroid glands of frog, fowl, dog, cattle and rat were used with different tissue preparation procedures. The best results were obtained in rats stimulated by previous intraperitoneal injection of sodium glycerophosphate. Bovine parathyroids were also positive after glutaraldehyde fixation and paraffin embedding.