To investigate differences among brain-derived microglia and other classes of immune cells, we compared the morphologies and growth properties of mononuclear phagocytes isolated from tissues of the newborn rat. Scanning EM shows that microglia from postnatal rat brain are covered with spines (typically > 20 per cell body) in a distinctive manner which contrasts the smooth surfaces of bone marrow cells and the ruffled surfaces of tissue macrophages from spleen, liver, and peritoneum. The spine-bearing surface of microglia is a specific cell marker, for it does not change with age or after exposure to cytokines or other immunostimulants. Approximately 99% of mononuclear phagocytes cultured from normal adult rat brain are spinous microglia. Five days after injury to rat brain, cells at sites of Wallerian degeneration are essentially all spinous ones while nearly 30% of cells found within areas of infarction or penetrating trauma are invading macrophages. In a similar way, nearly all cells isolated from normal, postmortem adult human brain are spine-bearing microglia (> 99% homogeneity). Brains from patients with amyotrophic lateral sclerosis contain only spinous microglia whereas cells from HIV-1 infected brains include significant numbers of invading ruffled macrophages. Cultured microglia, unlike cultured bone marrow precursors, monocytes, or tissue macrophages, spontaneously develop long, thin processes that extend hundreds of microns in length. Microglia retract these processes after exposure to fetal bovine serum, laminin, or such immunostimulants as recombinant murine interferon gamma (rmIFN gamma) and lipopolysaccharide. Of all types of mononuclear phagocytes tested, only microglia differentiate into quiescent ramified cells when in contact with astrocytes. Thus, microglia represent a unique class of cell maintained, in part, by astroglia as dormant, ramified mononuclear phagocytes in mature CNS. Application of cell surface criteria described here will allow study of distinct populations of mononuclear phagocytes associated with neurologic disorders.

Lissencephaly (smooth brain) is an abnormality of brain development characterized by incomplete neuronal migration and a smooth cerebral surface. At least two distinct pathological types occur, each associated with several recognized syndromes. In this paper, we report on the clinical and pathologic manifestations of four additional patients and classify and delineate three separate disorders with type II lissencephaly. We also report on a previously undescribed abnormality in one of the four patients--dilated rough endoplasmic reticulum cisternae containing an unknown osmiophilic secretory product, probably a glycoprotein.

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The authors report on 42 fatal gunshot wounds to the brain in civilians. The firearms used were those commonly available to civilians, ranging from a .22 revolver to a .45 semiautomatic pistol. Missle tracks were measured and the volume computed. The relatively low-velocity missles produced by these weapons to not create the devastation that characterizes wounds from high-velocity military firearms. Instead, there is much variation in the size of the missle tracks, and they cannot be directly related to caliber. Pressure marks and contusions, impaction of bone chips, internal richochet, and cerebral edema occurred frequently. The missle passed through the brain completely in very case but was retained by the skull or soft tissues in a large percentage of cases. The mechanism of death may be acute pressure on the brain stem from the passage of the missle through the brain.

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Long-term data from six sites in treeless subalpine and alpine vegetation in central Tasmania are used to document change in vegetation cover and life form dominance over time. All sites have been disturbed by burning and domestic stock grazing in the past. Although burning ceased at least 8 yr before initial measurements were taken, stock grazing still occurs at one site, and rabbits and native vertebrate herbivores (mainly wallabies) graze throughout the region. Vegetation cover increased across all sites over a 5-to 23-yr period at an average annual increment of approximately 1%. There was no significant relationship between the initial cover of bare ground and change in bare ground over time for most of the sites. Annual increases in vegetation cover were least in locations grazed by rabbits and native vertebrate herbivores and where domestic stock still grazed. Exclosures grazed only by rabbits had an intermediate rate of increase. Vegetation cover was found to increase most in ungrazed exclosures. The rates of increase in vegetation cover suggest that, in the absence of fire, it is a matter of decades before cover will be almost complete in the area.

BACKGROUND: Repeated injury, or recidivism, because of intentional or unintentional injury is a growing chronic health problem among urban adolescents and young adults in the United States. OBJECTIVE: To describe demographic, social, environmental, psychological, and developmental antecedents and risk-taking behaviors, and to examine their relationships to type of trauma and rate of trauma recidivism in adolescent and young adults in an urban trauma center. METHODS: One hundred adolescent and young adult trauma victims in an urban trauma center were interviewed, using the Adolescent Risk-Taking Instrument, the Brief Anger/Aggression Questionnaire, and the Trauma Risk Factor Interview Schedule. Bivariate correlation, multiple regression, and discriminant function analysis were used to examine the data. RESULTS: Of the sample, 89% experienced trauma related to interpersonal violence, including firearm injuries, stab wounds, and blunt trauma. Male gender, unemployment, past arrest, lower levels of spirituality, and higher levels of anger/aggression and thrill-seeking accounted for 25% of the variance in the number of risk-taking behaviors. Factors such as male gender, past arrest, unemployment, having been a crime victim in the past, lower autonomy, use of weapons, fighting, and no psychological counseling distinguished subjects with firearm-related injuries from subjects with other injury sources. Use of alcohol on weekdays, past arrest, and higher education levels were associated with trauma recidivism, explaining 14% of the variance. CONCLUSIONS: Social/environmental and psychological/developmental variables, as well as risk-taking behaviors, are important correlates of trauma and recidivism. These findings suggest the importance of advocacy for social policies conductive to reducing the risks of violence and trauma and risk-reduction interventions as components of posttrauma care.

The Cradle Mountain-Pencil Pine area, northern Tasmania, has a highly varied vegetation and a rich and highly Tasmanian endemic flora. The distributions of the synusiae and floristic plant communities in the region arc strongly influenced by geology, the altitudinal environmental gradient, drainage conditions and fire history.