HIV interactions with cells of the nervous system.

HIV can invade the CNS, where it replicates principally in macrophages. Yet, neurological disease is more often correlated with levels of neurotoxins or tumor necrosis factor alpha than with viral replication or specific viral determinants in brain. In experimental systems, HIV glycoprotein affects functions of uninfected microglia and astrocytes to eventually cause neuronal death. While the cellular basis of cognitive and neurological dysfunction are unravelled in the simian immunodeficiency virus model, the molecular mechanisms of HIV neurotoxicity are being studied in newly developed mouse models.

Use of fluorescence in situ hybridization (FISH) to study chromosomal damage induced by radiation and bromodeoxyuridine in human colon cancer cells.

PURPOSE: Although the thymidine analog radiation sensitizer bromodeoxyuridine (BrdUrd) increases radiation-induced chromosomal aberrations, it is not known whether these aberrations are uniformly distributed among chromosomes. Using fluorescence in situ hybridization, we carried out a study to test the hypothesis that BrdUrd-induced radiosensitization may be mediated by nonuniform chromosomal damage. METHODS AND MATERIALS: Log phase HT29 human colon cancer cells were exposed to 10 microM BrdUrd (or media alone) for one cell cycle, and the G1 cells were separated by centrifugal elutriation. Half of the control and BrdUrd samples were irradiated with 8 Gy. Cells were then incubated for 24-28 h, and metaphase spreads were prepared. Fluorescence in situ hybridization was performed using paint probes for chromosomes 1 and 4. RESULTS: We found that radiation induced 0.20 aberrations per chromosome in chromosome 4. Based on the ratio of the relative lengths of chromosome 1-4 (1.34), it was predicted that chromosome 1 would have approximately 0.26 aberrations per chromosome. However, we observed 0.39 aberrations per chromosome 1, which was significantly greater than the predicted (p < 0.001 by chi-square). Incubation with BrdUrd prior to irradiation significantly increased the aberrations found in chromosome 1 (by a factor of 1.4) and chromosome 4 (by a factor of 1.9) compared to radiation alone (p < 0.001) for both chromosome 1 and 4). CONCLUSION: This study demonstrates that individual chromosomes in human colon cancer cells show significantly different rates of aberration after irradiation. Furthermore, the BrdUrd-mediated increase in radiation-induced chromosomal aberrations may not be uniform among chromosomes.

HIV type 1 V3 sequences and the development of dementia during AIDS.

The most frequent neurological complication of AIDS is a dementia-like syndrome. Power and collaborators (J Virol 1994; 68:4643-4649) have reported an association between the clinical signs of AIDS dementia and the amino acid composition of two positions (305 and 329) within the V3 region of HIV-1 strains amplified from brain tissue. Similarly, we analyzed position 305 in the V3 region of HIV-1 present in the brain or cerebrospinal fluid of 25 nondemented subjects at different clinical stages of HIV-1 infection. Our results are, however, at variance with the findings presented by Power and colleagues. Histidine, found to be common among sequences derived from demented patients, was also present in the majority (16 of 25) of nondemented patients analyzed by us. In the hands of Power and colleagues, sequences derived from nondemented patients contained proline at position 305. None of our patients had proline in this position. We also asked the question whether the presence of a specific amino acid at position 305 of the V3 loop is linked to an increased capacity of HIV-1 isolates to infect primary microglial cells, the major target cell for HIV-1 infection in the brain. Primary HIV-1 isolates derived from blood and cerebrospinal fluid of five patients, two asymptomatic and three AIDS patients, were used to infect microglia cell cultures. Infection was monitored by syncytium formation and by p24 antigen release in the culture supernatant. All but one of the paired blood/CSF isolates replicated in human brain cultures. Replication occurred independently from the amino acid present at position 305 of the V3 region of the viral envelope. Our results indicate that the majority of HIV-1 isolates, even derived during the asymptomatic stage, have the capacity to infect microglial cells. The relevance of viral envelope sequences in determining tropism for microglial cells and development of neurological symptoms remains an open question.

Induction of oxidative stress in brain tissues of mice after subchronic exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

The ability of single doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to induce oxidative stress in hepatic and some extrahepatic tissues of animals is well documented. However, no previous study has examined the ability of TCDD to induce oxidative stress and tissue damage in brain in vivo. In this study the ability of TCDD to induce oxidative stress in brain tissues of mice was studied after subchronic exposures. Groups of female B6C3F1 mice were treated orally with TCDD (0, 0.45, 1.5, 15, and 150 ng/kg/day) for 13 weeks, 5 days/week. The animals were euthanized 3 days after the last treatment and brain tissues were collected. Biomarkers of oxidative stress including production of superoxide anion, lipid peroxidation, and DNA-single-strand breaks (SSB) were determined. TCDD treatment resulted in significant and dose-dependent increases in the production of superoxide anion as assessed by reduction of cytochrome c. Significant increases were also observed in lipid peroxidation and DNA-SSB in those tissues, as assessed by the presence of thiobarbituric acid-reactive substances and the alkaline elution technique, respectively. These results clearly indicate that subchronic exposure to low doses of TCDD can induce oxidative tissue damage in brain tissues which may at least in part play a role in the effects of TCDD on the central nervous system.

A weapon-related injury surveillance system in New York City.

CONTEXT: Assault injuries and deaths are a major public health problem in New York City but they are poorly understood because there is a dearth of information concerning them. OBJECTIVE: Develop and implement a low-cost, efficient, permanent weapon-related injury surveillance system (WRISS) for the city. DESIGN: WRISS was established, using a hierarchical exclusionary model, to capture all weapon-related (gunshot, stab, blunt instrument trauma) mortality and morbidity. SETTING: The five boroughs of New York City: The Bronx, Brooklyn, Manhattan, Queens, and Staten Island. PARTICIPANTS: NYC Vital Statistics Office, New York State hospital discharge database, Statewide Planning and Research Cooperative Systems (SPARCS), hospital emergency departments, and the police department. MAIN OUTCOME MEASURES: Surveillance system simplicity, acceptability, flexibility, cost. RESULTS: NYC WRISS is a simple surveillance system depending on both existing data sources and active data collection, and is therefore acceptable to providers. It is flexible and has allowed assault injuries without weapons to be added to better reflect domestic assaults. The cost is low, less than $60,000 per year. CONCLUSIONS: NYC WRISS is an efficient, cost-effective surveillance system, particularly suited to big cities with many assault injuries. Its low cost and obvious importance as a public health tool have allowed for its institutionalization, reflected by a permanent health department position, and annual reports alongside the more traditional public health surveillance systems. Analyses of data from 1990 to 1996 have lent new understanding to the decrease in homicides and assaults in New York City during that period.

Two secreted retinal factors regulate different stages of development of the outer blood-retinal barrier.

The retinal pigment epithelium (RPE) lies at the interface between the neural retina and the choriocapillaries where it forms a blood-retinal barrier. Like endothelial regions of the blood-brain barrier, the development of the RPE barrier is a gradual, multistep process. A culture model of chick RPE was used to study this development. The permeability of the tight junctions that limit diffusion between neighboring RPE cells was measured as the transepithelial electrical resistance (TER). Embryonic day 14 (E14) retinas were used to make a conditioned medium that lowered the permeability of cultured RPE. The TER of cultures prepared from E14 RPE was twice that of E7 RPE. In each culture, retinal conditioned medium increases the TER 2-2.5 fold. The active factors of conditioned medium that affected each culture had different physical properties. The factor that affected E7 was protease-resistant with a Mr<10 kDa, but the factor that affected E14 appeared to be a protein of approximately 49 kDa. Unlike the effect of astrocyte conditioned medium on endothelia, retinal conditioned medium did not act synergistically with cAMP. These data indicate that the chick retina, which lacks astrocytes, uses different diffusible factors to regulate different stages of tight junction development.

Is another mannose receptor-like lectin present in retinal pigment epithelium?

PURPOSE: This study was designed to investigate the presence of the secretory phospholipase A2 receptor in RPE, a protein closely related to the phagocytic mannose receptor. METHODS: Proteins from cultured rat, pig, and human RPE were separated by SDS-PAGE and immunoblotted with a polyclonal guinea pig sPLA2 receptor antibody. RT-PCR was performed on rat and pig RPE samples using primers designed from published rat pancreatic sPLA2 receptor sequences. RESULTS: The sPLA2 receptor protein was not detected in rat, pig, or human RPE by immunoblots. Additionally, message for this receptor was not detected in rat or pig RPE. CONCLUSIONS: With these techniques, these data demonstrate that the sPLA2 receptor is undetectable in the RPE.

Motor vehicle crash pedestrian deaths in New York City: the plight of the older pedestrian.

OBJECTIVE: To describe the epidemiology of pedestrian deaths due to motor vehicle crashes (MVCs) between age groups in New York City (NYC), with a comparison to national data. METHODS: Review of MVC pedestrian deaths in NYC and the US from 1998 to 2002. Data on deaths were obtained from the National Highway Traffic Safety Administration. RESULTS: Almost half (48%) of all MVC deaths in NYC were among pedestrians, compared with 12% nationally. Pedestrian death rates were highest among older age groups (> or =65 years). NYC's older pedestrians were more likely than US older pedestrians to be killed at an intersection, during daytime and on weekdays. CONCLUSION: Older people constitute a major proportion of MVC pedestrian deaths in NYC. Conditions (such as traffic exposure) surrounding pedestrian MVCs may differ by age group. The high burden of MVCs among older pedestrians in NYC highlights the importance of local-level analysis to guide public health planning.

Prevalence of domestic violence in the United States.

This comprehensive review of the literature reports on the annual and life-time prevalence of domestic violence against women in the United States. Data on population-based samples, pregnant women, and women treated in emergency rooms are each presented separately, as are the effects of age, marital status, socioeconomic status, race and ethnicity, and alcohol and drug use. Prevalence reports vary across studies, due in part to definitional issues and differences in the populations studied, but this is primarily true for lifetime and not for current prevalence. Prevalence is 0.3% to 4% for severe violence and 8% to 17% for total violence in the past year. Lifetime occurrence is 9% for severe violence and 8% to 22% for total violence. When minor as well as severe acts of physical violence toward women in the general female population are included, prevalence appears to be between 10% and 15% and somewhat higher for some subgroups.

Developing injury prevention capacity in New York City: the role of a local health department in fostering collaborations.

Injuries have long been a leading cause of mortality in urban areas such as New York City. While efforts to address injuries were undertaken by the New York City Department of Health (NYCDOH) starting in the 1940s, it was not until the department received a Capacity Building Grant from the Centers for Disease Control and Prevention (CDC) in 1989 that a more comprehensive program could be developed. The NYCDOH launched several collaborative projects with a variety of organizations and institutions. These efforts indicate that through collaborations, local health departments can increase their effectiveness and better promote their approach to injury prevention.

Knowledge, attitudes, treatment practices, and health behaviors of nurses regarding blood cholesterol and cardiovascular disease.

Knowledge, attitudes, and practice patterns concerning cholesterol and heart disease were evaluated in a stratified, random sample of 206 registered nurses at a major academic medical center in New York City. Virtually all nurses were convinced of the importance of diet in reducing heart disease risk, and most (78%) agreed that nutrition counseling should be their responsibility. Although only 19% reported that they were currently counseling, many more felt prepared to counsel about diet or drug therapy (43%). Nurses who were likely to counsel were those working in general medicine, those who were certified nurse practitioners, those who knew their own blood cholesterol level, and those with higher knowledge scores. Level of overall knowledge was associated with the practice of counseling, an attitude that counseling should be a nurse's responsibility, and personal health behavior (knew own level), regardless of age or occupational or degree status. Despite their enthusiasm for heart disease prevention through diet modification, many nurses had substantial knowledge gaps, suggesting that nurses are currently not adequately prepared to counsel about diet and/or drug treatment for high blood cholesterol. Educational strategies and considerations in integrating an expanded role for nurses with those of physicians and dietitians are discussed.

Pyridoxal phosphate-unrelated inhibition of hippocampal glutamic acid decarboxylase by convulsant pyridoxal sulphate.

Previous studies from this laboratory have shown that pyridoxal-5'-sulphate, the synthetic analogue of pyridoxal phosphate, causes epileptic seizures including tonic-clonic convulsions. These seizure activities are prevented or reversed by GABA or muscimol. In an attempt to delineate the biochemical basis of these seizure processes further, we have studied and shown that pyridoxal sulphate is a competitive inhibitor of glutamic acid decarboxylase. In addition, the chronic administration of pyridoxal sulphate was shown to reduce the concentration of pyridoxal phosphate in the cerebellum, the cerebrum, and basal ganglion, but not in the hippocampus. The activity of hippocampal glutamic acid decarboxylase was reduced after 1, 3, and 5 days of chronic application of pyridoxal sulphate. The inhibition was demonstrated, whether glutamic acid decarboxylase was assayed in the presence or absence of its coenzyme pyridoxal phosphate. Unlike findings in the hippocampus, the activity of glutamic acid decarboxylase in other brain regions was unaffected following chronic application of pyridoxal sulphate. The selective toxic effects of pyridoxal sulfate to the hippocampus, a brain area well known for its high susceptibility to seizure discharges, deserve additional indepth investigation.

Methapyrilene effects on initiation and promotion of gamma-glutamyl-transpeptidase positive foci in rat liver.

The initiating and promoting effects of methapyrilene were evaluated using the hepatic enzyme-altered foci bioassay. Male Sprague-Dawley rats were partially hepatectomized and 24 hours later were administered either methapyrilene or nitrosodiethylamine by oral gavage. Subsequently, the animals were promoted with 500 ppm2 phenobarbital or 200 ppm methapyrilene in drinking water for eight weeks. Fresh frozen sections of liver were then stained and scored for gamma-glutamyl-transpeptidase (GGT)-positive foci. Methapyrilene, when tested as the nominal initiator at a single dose of 50 mg/kg or at two doses of 130 mg/kg and promoted by phenobarbital, did not induce foci above background levels. However, when substituted for phenobarbital as the promoting agent following nitrosodiethylamine initiation, methapyrilene enhanced enzyme-altered foci formation to an equal or greater extent than did the promoter phenobarbital. These results suggest that the carcinogenic effects of methapyrilene may be related to its ability to enhance hepatic tumorigenesis.

Heterodimerization of calcium sensing receptors with metabotropic glutamate receptors in neurons.

Calcium sensing (CaR) and Group I metabotropic glutamate receptors exhibit overlapping expression patterns in brain, and share common signal transduction pathways. To determine whether CaR and Group I metabotropic glutamate receptors (mGluRs) (mGluR1alpha and mGluR5) can form heterodimers, we immunoprecipitated CaR from bovine brain and observed co-precipitation of mGluR1alpha. CaR and mGluR1alpha co-localize in hippocampal and cerebellar neurons, but are expressed separately in other brain regions. In vitro transfection studies in HEK-293 cells established the specificity and disulfide-linked nature of the CaR:mGluR1alpha (CaR:mGluR5) interactions. CaR:mGluR1alpha (CaR:mGluR5) heterodimers exhibit altered trafficking via Homer 1c when compared with CaR:CaR homodimers. CaR becomes sensitive to glutamate-mediated internalization when present in CaR:mGluR1alpha heterodimers. These results demonstrate cross-family covalent heterodimerization of CaR with Group I mGluRs, and increase the potential role(s) for CaR in modulating neuronal function.

The epidemiology and causes of injuries resulting in hospitalization in New York City: 1990-1992.

The purpose of this study is to present data on the distribution and etiology of nonfatal injuries resulting in hospital discharges in New York City (NYC). Records of all NYC residents discharged for injuries from acute stay hospitals 1990-1992 were tabulated. Injuries from surgical and medical procedures, adverse effects of drugs in therapeutic use, and late effects of injury were excluded. The results indicate that there was a marked geographic variation in rates: higher rates of assaults, self-inflicted injuries, burns, unintentional injuries from firearms, and injuries to bicyclists in disadvantaged neighborhoods. The data show that injuries in NYC have distinctive features that should form the basis for targeted prevention activities.

Persistent poliovirus infection in mouse motoneurons.

Poliovirus (PV) is the causal agent of paralytic poliomyelitis. Many survivors of the acute disease, after decades of clinical stability, develop new muscular symptoms called postpolio syndrome. It has been hypothesized that the persistence of PV in the spinal cord is involved in the etiology of this syndrome. To investigate the ability of PV to persist in the spinal cord after the onset of paralysis, we exploited a mouse model in which most animals inoculated with a mouse-adapted mutant survived after the onset of paralysis. Light microscopy and ultrastructural immunohistochemical studies and reverse transcription followed by nested PCR performed on spinal cord from paralyzed mice demonstrated that PV persisted in the mouse spinal cord for at least 12 months after the onset of paralysis. This mouse model provides a new tool for studying poliomyelitis evolution after the onset of paralysis.

Species differences in the generation of reactive oxygen species by microglia.

Although a variety of potential sources for reactive oxygen species (ROS) exist in the CNS, brain macrophages, i.e., the microglia, generate large quantities of these reactive species, particularly in response to injury or inflammatory signals. In order to understand how microglia contribute to changes in oxidative status of the CNS and how this might related to disease states, such as Alzheimer disease (AD), we have examined the regulation of superoxide anion and nitric oxide production from rodent and human microglia. Our results indicate that microglia from all species we have studied release superoxide anion, but produce significantly different amounts in response to the same activating agents. Species differences are also found in the ability to generate nitric oxide (NO). In particular, mouse microglia generate large quantities of NO when stimulated, but human and hamster microglia do not produce measurable amounts under the same stimulation conditions. These species differences are important to consider when modeling human disease processes from rodent studies.

The role of zinc and zinc-binding proteins in regulation of glutamic acid decarboxylase in brain.

At physiological concentrations, zinc stimulates the activity of pyridoxal kinase, enhancing the formation of pyridoxal phosphate, which in turn enhances the activity of glutamic acid decarboxylase. In toxic doses, zinc inhibits glutamic acid decarboxylase directly and may adversely influence the GABA receptor sites. Zinc-binding proteins, which are inducible by zinc, have been identified in brain and regulate the steady state concentration of free Zn2+. Since free Zn2+ is a potent inhibitor of numerous sulfhydryl-containing enzymes, including glutamic acid decarboxylase, we conclude that zinc-binding proteins not only may function as a physiological donors of Zn2+ to zinc apometalloenzymes, but also may play a decisive role in preventing CNS toxicity by preventing the rise of free Zn2+ in the brain.

Evidence for oxidative damage in a murine leukemia virus-induced neurodegeneration.

Vacuolation in cellular organelles within the central nervous system is a common manifestation of oxidative injury. We found that the spongiform vacuolation observed in PVC-211 murine leukemia virus (PVC-MuLV) neurodegeneration was associated with oxidative damage as detected by immunoreactivity for 3-nitrotyrosine and protein carbonyl groups. This oxidative injury was present in brain before or concomitant with the appearance of activated microglia, vacuolation, and gliosis that characterize PVC-MuLV neuropathology. Treatment of infected F344 rat pups with the antioxidant vitamin E transiently protected and prolonged the latency of PVC-MuLV neurodegeneration. Taken together, these findings implicate oxidative damage and lipid peroxidation in the pathogenesis of PVC-MuLV neurodegeneration. This animal model may be useful for studies of mechanisms and potential therapies for progressive neurodegeneration following a well-defined insult.