Comparative analysis of cortical layering and supragranular layer enlargement in rodent carnivore and primate species

The mammalian cerebral cortex is composed of individual layers characterized by the cell types they contain and their afferent and efferent connections. The current study examined the raw, and size-normalized, laminar thicknesses in three cortical regions (somatosensory, motor, and premotor) of fourteen species from three orders of mammals: primates, carnivores, and rodents. The proportional size of the pyramidal cell layers (supra- and infragranular) varied between orders but was similar within orders despite wide variance in absolute cortical thickness. Further, supragranular layer thickness was largest in primates (46 +/- 3 percent), followed by carnivores (36 +/- 3 percent), and then rodents (19 +/- 4 percent), suggesting a distinct difference in the proportion of cortex devoted to corticocortical connectivity across these orders. Although measures of supragranular layer thickness are highly correlated with measures of overall brain size, such associations are not present when independent contrasts are used to control for phylogenetic inertia. Interestingly, neurogenesis time span remains strongly associated with supragranular layer thickness despite size normalization and controlling for phylogenetic inertia. Such layering differences between orders, and similarities amongst species within an order, suggest that supragranular layer expansion may have occurred early in mammalian evolution and may be related to ontogenetic variables such as neurogenesis time span rather than measures of overall size.

Wrist slashing in a detention center. Case report and review of the literature

Suicides that occur in custody are rare and thus require extensive forensic analysis. Asphyxia by hanging is the most common means of suicide: at least 87.5% of successful suicides are committed in this way. A unique case of suicide in custody is presented in which a prisoner slashed his wrist with an eyeglass lens. The evidence and proceedings that led to this suicide are reviewed and the data are compared with known behavioral patterns. The world literature concerning suicide while incarcerated is reviewed.

Immunosuppressive effects of Centipeda periodontii: selective cytotoxicity for lymphocytes and monocytes

We have examined soluble sonic extracts prepared from several strains of Centipeda periodontii for their ability to alter human lymphocyte function. These organisms were isolated from subgingival plaque of patients with periodontal disease. We found that sonicates from several, but not all, strains of C. periodontii caused a dose-dependent inhibition of lymphocyte responsiveness to concanavalin A, phytohemagglutinin, pokeweed mitogen, and formalinized Staphylococcus aureus. Inhibition was associated with a concomitant decrease in cell viability assessed by trypan blue exclusion, 51Cr release, and electron microscopy. The maximal number of dead cells was observed 20 to 24 h after exposure to the sonic extract. Susceptible cells include human lymphocytes (both B and T), monocytes, and erythrocytes, whereas polymorphonuclear cells, murine L-929 fibroblasts, and sheep erythrocytes were not affected. Preliminary characterization of the cytotoxic activity indicates that it is heat labile and trypsin sensitive and has an Mr of 60,000. It has been proposed that impaired host defense may play a pivotal role in the pathogenesis of periodontal diseases. The data presented in this paper suggest that immunosuppression (local or systemic or both) could be initiated by C. periodontii. This immunosuppression may alter the nature and consequences of host-parasite interactions, thereby enhancing the pathogenicity of C. periodontii itself or some other opportunistic organism.