Symptoms of dissociation were prevalent in healthy subjects exposed to high stress. Stress-hardy individuals (Special Forces soldiers) experienced fewer symptoms of dissociation, compared to individuals who were less hardy. These data support the idea that the nature of response to previously experienced threatening events significantly determines the nature of psychological and somatic response to subsequent stress.

The germ line and soma together maintain genetic lineages from generation to generation: the germ line passes genetic information between generations; the soma is the vehicle for germ line transmission, and is shaped by natural selection. The germ line and somatic lineages arise simultaneously in early embryos, but how their development is related depends on how primordial germ cells (PGC) are specified. PGCs are specified by one of two means. Epigenesis describes the induction of PGCs from pluripotent cells by signals from surrounding somatic tissues. In contrast, PGCs in many species are specified cell-autonomously by maternally derived molecules, known as germ plasm, and this is called preformation. Germ plasm inhibits signaling to PGCs; thus, they are specified cell-autonomously. Germ plasm evolved independently in many animal lineages, suggesting convergent evolution, and therefore it would be expected to convey a selective advantage. But, what this is remains unknown. We propose that the selective advantage that drives the emergence of germ plasm in vertebrates is the disengagement of germ line specification from somatic influences. This liberates the evolution of gene regulatory networks (GRNs) that govern somatic development, and thereby enhances species evolvability, a well-recognized selective advantage. We cite recent evidence showing that frog embryos, which contain germ plasm, have modified GRNs that are not conserved in axolotls, which represent more basal amphibians and employ epigenesis. We also present the correlation of preformation with enhanced species radiations, and we discuss the mutually exclusive trajectories influenced by germ plasm or pluripotency, which shaped chordate evolution.

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Many orthopaedic surgeons had abandoned the use of first and second generation total ankle arthroplasties due to unacceptably high complication and failure rates as compared to arthrodesis. Recently, there has been renewed interest in ankle joint replacement as longer term outcome studies have become available, and the FDA has approved several more designs. With the introduction of two new FDA approved implants in November 2006, options for surgeons interested in total ankle arthroplasty have greatly expanded. There continues to be much debate within the orthopaedic community as to indications, patient selection, and optimal component design. This review aims to provide orthopaedists with an overview of the currently available implants and literature.

In a group of 160 patients who had hindfoot fusions (isolated subtalar, talonavicular, and calcaneocuboid fusions and double and triple arthrodeses), smokers had a significantly higher rate of nonunion than did nonsmokers (18.6% vs. 7.1%). The relative risk of developing a nonunion was 2.7 times higher for smokers than non-smokers. With the numbers available, there was a trend for patients who had quit smoking prior to surgery to have a higher rate of nonunion (11.1%) than patients who had never smoked, but not as high as those who continued to smoke. There was no statistical difference in the rate of infection or delayed wound healing among the groups.

The sesamoids of the great toe, which are small and seemingly insignificant bones, can be the site of disabling pathology for the athlete. Sesamoiditis, osteochondritis, partite sesamoids with stress fractures, displaced fractures, and osteomyelitis have all been reported in the athlete. Bursitis beneath the tibial sesmoid and flexor hallucis brevis tendonitis also occur in the athlete and may be confused with sesamoid injury. Excision of the involved bone is the recommended treatment for displaced fractures and for less severe conditions such as sesamoiditis, osteochondritis, and nondisplaced fractures, if conservative management fails to relieve symptoms.

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The distal metatarsal angle (DMAA) is a measurement of the relationship between the longitudinal axis of the first metatarsal and the articular surface of the metatarsal head. We measured the DMAA on radiographs with and without markers on the articular edges and compared them with measurements of the anatomic specimens. Based on the studies, the significance of the radiographic measurements to the actual DMAA and the normal distribution of the measurement were determined.