Far from a monolith: a typology of externalizing behavior among African American youth

Purpose

Previous studies have examined externalizing behaviors among African American youth using variable-centered approaches that study aggression and delinquency separately. However, aggression and delinquency often operate together in shaping adolescent behavior. For this reason, person-centered approaches are essential for identifying subgroups of African American youth using multiple indicators of aggression and delinquency to model the behavioral heterogeneity within this population. We examined the relationship between interpersonal, school, and parenting factors and externalizing behaviors among African American youth.

Method

Drawing from the National Survey on Drug Use and Health 2015–2018, we conducted latent class analysis based on 5 externalizing behavior indicator variables (i.e., serious fight, attack to harm, stealing, drug selling, handgun carrying) using a sample of 7,236 African American adolescents, aged 12–17.

Results

We identified a three class solution: Class #1—No Involvement (74.4%), characterized by very low levels of involvement in all of the externalizing behaviors examined; Class #2—Serious fight (23.3%), which is characterized by near-universal involvement in a serious fight, far lower levels of attack to harm, and negligible levels of stealing, drug selling, and handgun caring; and Class #3—Multidimensional externalizing (2.3%), characterized by very high levels of involvement in all of the externalizing variables examined.

Conclusion

Most African American youth are not involved in externalizing behaviors. It is vital to support both the large majority of African-American youth who are abstaining from externalizing behaviors and to develop/implement programs to address the contextual and interpersonal needs of youth at elevated risk for consequences related to externalizing.

     

Cerebral cortex lesions decrease the number of bromodeoxyuridine-positive subventricular zone cells in mice

We previously showed that cortical lesions in rats increase the number of subventricular zone (SVZ) cells. Here, we examined the response of the SVZ to cortical lesions in mice from 6 h to 35 days later. Whereas the total number of cells did not change, the number of cells in S-phase (bromodeoxyuridine-positive) decreased in a biphasic manner (from 6 h to day 3, and again at days 25-35). In addition, there was a delayed (days 25-35) increase in immunoreactivity for polysialylated neural cell adhesion molecule, a marker of neuroblasts. The results suggest that in mice there are rapid as well as delayed responses in the SVZ to injury of the overlying cerebral cortex. They also show that the SVZ of different mammalian species can exhibit widely divergent responses to the same brain injury.     

Human cardiac gap junctions: isolation, ultrastructure, and protein composition

Recent experiments from our laboratory have shown that the ultrastructure and protein composition of gap junctions isolated from rat ventricles are tissue specific, i.e., markedly different from gap junctions of liver and lens. The differences include a cytoplasmic surface component characteristic for cardiac gap junctions; this component can be visualized by two ultrastructural techniques: as a fuzzy layer in electron micrographs of thin-sectioned junctional pellets and as cytoplasmic surface particles in deep-etched freeze-fractured junctions. The component corresponds to a Mr 17,500 cytoplasmic surface domain of each of the six (Mr 47,000) rat heart gap junctional channel protein subunits that make up the gap junctional channel hexamer known as a connexon. The cytoplasmic surface component is localized at the carboxy-terminal of the subunit. Within the cytoplasmic surface component, rat cardiac gap junctions are cross-linked by disulfide linkages between subunits of the same connexon and between subunits of adjacent connexons. By contrast, the Mr 28,000 liver gap junctional subunit lacks a comparably large cytoplasmic surface component, cytoplasmic surface fuzz, cytoplasmic surface particles, and intra- and interconnexon disulfide linkages. Most of these unique characteristics of cardiac gap junctions were discovered in junctions isolated from rat ventricles. Unlike liver and lens gap junctions, cardiac gap junctions from humans, non-human primates, or other large mammals have not previously been isolated and characterized. Here we report the isolation of unproteolyzed gap junctions from the ventricle of a 24 year-old man with advanced cardiomyopathy whose heart was removed for replacement by a transplanted heart.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quality assurance management methods applied to a local-level primary health care system in rural Nigeria

Introduction. Management of primary health care (PHC) systems in less developed countries is often impeded by factors such as poorly trained personnel, limited financial resources, and poor worker morale. This study explored the ability of local-level PHC supervisors in rural Nigeria to use quality assurance (QA) management methods to improve the quality of the PHC system. Methods. PHC supervisors from Bama Local Government Area were trained for 3 days in the use of QA methods and tools. The supervisors targeted the supervisory system and the health information system (HIS) for improvement. Health worker performance in diarrhoea case management was assessed, using a simulated case, to measure the impact of supervision. A HIS audit assessed data collection forms used by 17 PHC facilities. Gaps in quality were monitored over a 2-month study period and flaws in work processes were modified. Results. PHC supervisors introduced a checklist during monthly visits to facilities to monitor how workers managed cases of diarrhoea. Performance in history-taking, physical examination, disease classification, treatment and counselling improved over the evaluation period. The HIS audit found that a variety of reporting forms were used at PHC facilities. After HIS reporting was standardized, the number of health facilities using a daily disease registry significantly improved during the study period. Conclusions. QA management methods were used by PHC supervisors in Nigeria to improve supervision and the HIS. QA management methods are appropriate for improving the quality of the PHC in Nigeria and in other less developed countries where at least a minimal PHC infrastructure exists.     

Sporadic community-acquired Legionnaires' disease in the United States. A case-control study.

One hundred patients with sporadic, community-acquired, serologically confirmed Legionnaires' disease were matched with control subjects known by the patients (acquaintance controls) and control subjects chosen from among patients with negative serodiagnostic tests for Legionnaires' disease (clinical controls). Each clinical control subject was also matched with an acquaintance control of his own. Legionnaires' disease patients had smoked more cigarettes, consumed more alcohol, and were more likely to have resided near excavation sites than acquaintance or clinical control subjects. Parallel differences between clinical controls and their acquaintances were not seen. Legionnaires' disease patients had traveled away from home for more time during the 2 weeks before onset of illness than had their acquaintances. The difference was of greater magnitude than that between clinical control subjects and their acquaintances. Legionnaires' disease patients were more likely to have resided near construction sites than clinical controls, and there were more construction workers among patients than among clinical control subjects.     

Attacks Intended to Seriously Harm and Co-occurring Drug Use Among Youth in the United States

Background: While it is known that substance use and violence co-occur, less is understood in terms of how this relationship might vary based on the degree of youth involvement in violence. Objectives: This study sought to examine the prevalence and degree that substance use disorders (SUD) and related intrapersonal and contextual factors were associated with violent attacks. Method: Repeated cross-sectional data from a population-based study (National Survey on Drug Use and Health) of youth ages 12–17 (n = 216,852) in the United States between 2002 and 2013 were pooled to increase the analytic sample size. Survey multinomial regression was used to examine psychosocial and substance use differences between youth reporting episodic (1–2 times, n = 13,091; 5.84%) and repeated violent attacks (3+ times, n = 1,819; 0.83%) in contrast with youth reporting no attacks. Additional analyses examined the association of sociodemographic, intrapersonal, and contextual factors with SUD among youth reporting violent attacks. Results: The prevalence of SUD among youth with no attacks was 6% compared to 22% among episodic and 36% among repeatedly violent youth. Violence-involved youth were substantially more likely to experience elevated sensation-seeking, easy drug access, and recent drug offers and less likely to benefit from religiosity and protective substance use beliefs. Conclusions/Importance: Findings highlight the importance of distinguishing between the various gradations of violence among youth in understanding the relationship between substance use and violence, and shed light on the intrapersonal and contextual factors that can help identify violent youth at greatest risk for substance use problems.     

Radial glia-like cells at the base of the lateral ventricles in adult mice

During development radial glia (RG) are neurogenic, provide a substrate for migration, and transform into astrocytes. Cells in the RG lineage are functionally and biochemically heterogeneous in subregions of the brain. In the subventricular zone (SVZ) of the adult, astrocyte-like cells exhibit stem cell properties. During examination of the response of SVZ astrocytes to brain injury in adult mice, we serendipitously found a population of cells in the walls of the ventral lateral ventricle (LV) that were morphologically similar to RG. The cells expressed vimentin, glial fibrillary acidic protein (GFAP), intermediate filament proteins expressed by neural progenitor cells, RG and astrocytes. These RG-like cells had long processes extending ventrally into the nucleus accumbens, ventromedial striatum, ventrolateral septum, and the bed nucleus of the stria terminalis. The RG-like cell processes were associated with a high density of doublecortin-positive cells. Lesioning the cerebral cortex did not change the expression of vimentin and GFAP in RG-like cells, nor did it alter their morphology. To study the ontogeny of these cells, we examined the expression of molecules associated with RG during development: vimentin, astrocyte-specific glutamate transporter (GLAST), and brain lipid-binding protein (BLBP). As expected, vimentin was expressed in RG in the ventral LV embryonically (E16, E19) and during the first postnatal week (P0, P7). At P14, P21, P28 as well as in the adult (8-12 weeks), the ventral portion of the LV retained vimentin immunopositive RG-like cells, whereas RG largely disappeared in the dorsal two-thirds of the LV. GLAST and BLBP were expressed in RG of the ventral LV embryonically and through P7. In contrast to vimentin, at later stages BLBP and GLAST were found in RG-like cell somata but not in their processes. Our results show that cells expressing vimentin and GFAP (in the radial glia-astrocyte lineage) are heterogeneous dorsoventrally in the walls of the LV. The results suggest that not all RG in the ventral LV complete the transformation into astrocytes and that the ventral SVZ may be functionally dissimilar from the rest of the SVZ.     

Migration patterns of subventricular zone cells in adult mice change after cerebral cortex injury

The subventricular zone (SVZ) generates the largest number of migratory cells in the adult brain. SVZ neuroblasts migrate to the olfactory bulbs (OB) in the adult, whereas during development, SVZ cells migrate into many adjacent nuclei. Previously, we showed that cerebral cortex injury in the adult causes molecular and cellular changes which may recapitulate the developmental migratory directions. Consistent with this, growth factors, as well as models of illness or injury can cause adult SVZ cells to migrate into non-olfactory bulb nuclei. Here, we tested the hypothesis that cerebral cortex injury in the adult mouse induces changes in migration, by labeling adult SVZ cells with a retroviral vector and examining the distribution of cells 4 days and 3 weeks later. Four days after cortical lesions, disproportionately fewer retrovirally-labeled cells had migrated to the olfactory bulb in lesioned mice than in controls. Conversely, the number of cells found in non-olfactory bulb regions (primarily the area of the lesion and the corpus callosum) was increased in lesioned mice. The morphology of these emigrated cells suggested that they were differentiating into glial cells. Three weeks after cortical injury, the majority of retrovirally-labeled cells in both groups of mice had migrated into the granule and periglomerular layers of the olfactory bulb. At 3 weeks, we still observed retrovirally-labeled glial cells in the corpus callosum and in the area of the injury in lesioned mice. These results suggest that cortical lesions cause a transient change in migration patterns of SVZ progeny, which is characterized by decreases in migration to the olfactory bulb but increased migration towards the injury. Our studies also suggest that cortical lesions induce the production of new glial cells which survive for at least 3 weeks after injury. The data support the concept that in the adult, SVZ cells can generate progeny that migrate towards injured areas and thus potentially be harnessed for neural repair.     

Cardiac gap junctions and gap junction-associated vesicles: ultrastructural comparison of in situ negative staining with conventional positive staining

By comparing in situ negative staining of mammalian heart muscle using La(NO3)3 with conventional positive staining by uranium and lead salts, we showed that 1) the membrane area of rat cardiac gap junctions (GJs) at the intercalated disks is threefold to fourfold greater than previously thought; 2) connexon arrays of cardiac GJ are subdivided into microdomains by connexon-free aisles; 3) profiles of GJ-associated vesicles (GJAVs) of plasmalemmal origin (which are present extracellularly and sharply localized at three extracellular sites) are paired to form GJs with each other and with myocyte plasmalemma; 4) some GJAVs contain arrays of assembled connexons; and 5) myocytes contain intracytoplasmic complexes lying within cylindrical or cigar-shaped membranes and consisting of GJs and multiple vesicles apparently dissociating from these GJs.