Abnormal brain structure in youth who commit homicide.

BACKGROUND: Violence that leads to homicide results in an extreme financial and emotional burden on society. Juveniles who commit homicide are often tried in adult court and typically spend the majority of their lives in prison. Despite the enormous costs associated with homicidal behavior, there have been no serious neuroscientific studies examining youth who commit homicide. METHODS: Here we use neuroimaging and voxel-based morphometry to examine brain gray matter in incarcerated male adolescents who committed homicide (n = 20) compared with incarcerated offenders who did not commit homicide (n = 135). Two additional control groups were used to understand further the nature of gray matter differences: incarcerated offenders who did not commit homicide matched on important demographic and psychometric variables (n = 20) and healthy participants from the community (n = 21). RESULTS: Compared with incarcerated adolescents who did not commit homicide (n = 135), incarcerated homicide offenders had reduced gray matter volumes in the medial and lateral temporal lobes, including the hippocampus and posterior insula. Feature selection and support vector machine learning classified offenders into the homicide and non-homicide groups with 81% overall accuracy. CONCLUSIONS: Our results indicate that brain structural differences may help identify those at the highest risk for committing serious violent offenses.

Determination of seasonality in southern hairy-nosed wombats (Lasiorhinus latifrons) by analysis of fecal androgens.

Little is known about the reproductive biology of Australia's critically endangered northern hairy-nosed wombat (Lasiorhinus krefftii), largely due to its cryptic nature and the difficulty in accessing the small remaining population of about 70 animals. Using the noninvasive technique of fecal steroid analysis, we have examined the endocrinology of the more common yet closely related southern hairy-nosed wombat (Lasiorhinus latifrons). The aims of this study were to 1) develop and validate fecal androgen analysis in this species, 2) examine and compare seasonal differences in fecal and plasma androgens in male wombats, and 3) correlate seasonal differences in androgens with changes in male accessory glands (prostate and bulbourethral gland). Fecal androgens were extracted in ether; concentrated; separated by HPLC into testosterone (T), dihydrotestosterone (DHT), and 5 alpha-androstane-3 alpha,17 beta-diol (Adiol) fractions; and quantitated by RIA. The concentrations of androgens in fecal pellets from 14 wild southern hairy-nosed wombats as determined by RIA varied over the range 6.6-25.0 ng/g dry weight for T, 4.0-24.2 ng/g dry weight for DHT, and 0-34.8 ng/g dry weight for Adiol. For each androgen, a highly significant linear correlation was observed between plasma and fecal concentrations. When individuals were grouped into either breeding season (pellets collected between August-November) or nonbreeding season (collected between February-April), significant (P < 0.05) differences between seasons were observed for both plasma and fecal T, plasma DHT, and fecal Adiol. For all androgens, the mean fecal and plasma concentrations were higher during the breeding season than the nonbreeding season. A significant (P < 0.001) correlation was observed between fecal T and prostate weight, while DHT and Adiol correlations were nonsignificant. Significant correlations were observed, however, between all three fecal androgens and bulbourethral gland weight. These studies demonstrate that fecal T is a valid indicator of reproductive status in the male southern hairy-nosed wombat, with significant correlations observed between fecal T, plasma T, and prostate and bulbourethral gland weights. These findings have important implications for the study of the reproductive endocrinology of the critically endangered northern hairy-nosed wombat.

Effect of cooling and cryopreservation on sperm motility and morphology of several species of marsupial.

The effects of long-term cooling and freezing on sperm motility are described for six marsupial species: the fat-tailed dunnart, koala, brushtail possum, long-footed potoroo, northern brown bandicoot and ring-tailed possum. The effects of up to eight days of cooling at 4 degrees C on the motility of dunnart spermatozoa and the effect of cryopreservation on spermatozoa of the other species were determined. The cryoprotectant used was a Tris-citrate-fructose-egg yolk-glycerol diluent. The percentage and rating of sperm motility, and sperm structure, as determined by light microscopy, were investigated. Sperm motility in the fat-tailed dunnart was retained for up to six days when cooled to 4 degrees C, suggesting that sperm from this species have some degree of tolerance to cold shock. After this time, however, the percentage of motile spermatozoa and their motility rating declined. In all species except the fat-tailed dunnart, reinitiation of motility following cryopreservation occurred across a range of glycerol concentrations (4-17%). Cryoprotectant containing 6% and/or 8% glycerol resulted in little change of motility rating or of the percentage of live sperm after thawing, although there was some decline in the percentage of motile sperm. The unusual structural and motility characteristics of dunnart spermatozoa may account for the lack of success of sperm cryopreservation in this species.