Persistent DDT metabolite p,p'-DDE is a potent androgen receptor antagonist.

The increase in the number of reports of abnormalities in male sex development in wildlife and humans coincided with the introduction of 'oestrogenic' chemicals such as DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) into the environment. Although these phenotypic alterations are thought to be mediated by the oestrogen receptor, they are also consistent with inhibition of androgen receptor-mediated events. Here we report that the major and persistent DDT metabolite, p,p'-DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene), has little ability to bind the oestrogen receptor, but inhibits androgen binding to the androgen receptor, androgen-induced transcriptional activity, and androgen action in developing, pubertal and adult male rats. The results suggest that abnormalities in male sex development induced by p,p'-DDE and related environmental chemicals may be mediated at the level of the androgen receptor.

Characterisation of ramified microglial cells: detailed morphology, morphological plasticity and proliferative capability.

Several cellular properties of brain microglia in the rat were investigated using both whole tissue and cultures of dissociated cerebral cortical cells. As revealed by thiamine pyrophosphatase histochemistry, tissue microglia possessed a highly distinctive cellular morphology. Stained microglia showed similar overall features of morphology and distribution in both preparations; however, the cells in culture displayed some slight differences from those of the tissue, including larger somata and less developed processes. Through studying living ramified cells in culture, both morphological plasticity as evidenced by patterned variations in soma size and mitotic activity were directly confirmed. It was concluded that ramified microglia definitely possess proliferative capability, and this may reduce the need for blood cell recruitment in brain immune responses. In addition, cultured microglia exist in a somewhat more activated state than those in normal tissue, and in some instances undergo further activation as macrophages. This cortical tissue culture system should provide an amenable preparation for investigating the regulation of microglial function.

Combined obturator and palatal-lift prosthesis: a case report.

A technique for the fabrication of a combined obturator and palatal-lift prosthesis is presented. The metal framework embodied the principles of partial denture design. A sequence of steps was used to achieve an accurate representation of the pharyngeal tissues, on which the pharyngeal extension was constructed. This extension was fabricated in an autopolymerizing acrylic resin to avoid lengthy laboratory procedures.

A metal insert to replace a fractured segment of a mandibular complete denture.

When surgical reduction is not possible for edentulous patients with little space between the retromolar pad and the maxillary tuberosity, dentures are most often made quite thin and as such are prone to fracture. When fracture of the lower denture base occurs, the denture is rebased, incorporating a case metal insert in the region of the previous fracture. Following the impression procedure, a pattern is developed on the master cast of the area to be replaced in metal. A casting is made in silver-palladium alloy and incorporated in the final wax-up. The denture is then processed by joining the metal insert into the denture.