Drug scene roles and HIV risk

AIMS: Drug scenes (social and spatial drug-using and drug-selling environments) have complex role structures. Many drug injectors earn money or drugs as drug or syringe sellers, hit doctors (people who help others to inject) commercial sex workers, or in other roles. This paper aims to measure "role behaviors" of drug injectors; describe which drug injectors are more likely to engage in such role behaviors; and to determine whether roles are related to elements of HIV risk. DESIGN: Cross-sectional study of drug injectors. SETTING: Bushwick, a section of Brooklyn, New York, a major location for injection drug use and drug sales. PARTICIPANTS: Seven hundred and sixty-seven street-recruited drug injectors. MEASUREMENTS: Participants were interviewed about their roles, behaviors, socio-demographics and risk networks; sera were collected and assayed for HIV and hepatitis B core antibody. FINDINGS: Socio-demographic variables are related to role-holding in complex ways. Economic need is generally associated with engaging in drug-scene role behaviors. Holders of these roles are at greater behavioral and network risk for HIV and other blood-borne infections than are other drug injectors. They also engage in extensive communication with other drug users, including discussion of HIV risk reduction. CONCLUSION: Role behaviors can be measured in quantitative studies, and seem to be related to HIV risk. Role-holders may be strategic targets for risk-reduction campaigns. It seems feasible and advisable to measure drug scene role-holding in research on drug users.     

Neuropsychological performance and CD4 levels in HIV-1 asymptomatic infection

The performance of 68 HIV-1 seropositive asymptomatic (HIV+) subjects stratified on CD4 levels were compared with 82 HIV-1 seronegative (HIV-) subjects on a battery of neuropsychological, mood state, and perceived health status measures. The neuropsychological test battery included measures of attention, reaction time, memory, intellectual ability, psychomotor speed, frontal lobe or "executive" function, and decision time. None of the HIV+ subjects were taking antiviral agents. The groups did not differ for age, mood state, or WAIS-R Verbal and Performance IQ scores. Due to group differences for education and weekly ethanol consumption, both variables were used as covariates in multivariate analyses of variance. Relatively few differences were observed between subgroups of HIV+ patients or between these subgroups and control subjects. These data suggest that factors other than absolute levels of immunosuppression as expressed by CD4 levels alone, appear to be responsible for the deficits observed in HIV+ asymptomatic patients.     

Determining cutting parameters in wire EDM based on workpiece surface temperature distribution

The material removal process in wire electrical discharge machining (WEDM) may result in work-piece surface damage due to the material thermal properties and the cutting parameters such as varying on-time pulses, open circuit voltage, machine cutting speed, and dielectric fluid pressure. A finite element method (FEM) program was developed to model temperature distribution in the workpiece under the conditions of different cutting parameters. The thermal parameters of low carbon steel (AISI4340) were selected to conduct this simulation. The thickness of the temperature affected layers for different cutting parameters was computed based on a critical temperature value. Through minimizing the thickness of the temperature affected layers and satisfying a certain cutting speed, a set of the cutting process parameters were determined for workpiece manufacture. On the other hand, the experimental investigation of the effects of cutting parameters on the thickness of the AISI4340 workpiece surface layers in WEDM was used to validate the simulation results. This study is helpful for developing advanced control strategies to enhance the complex contouring capabilities and machining rate while avoiding harmful surface damage.     

Substrate requirements of bacterial phosphatidylinositol-specific phospholipase C

A series of symmetric short-chain phosphatidylinositols (PI), including dihexanoyl-PI, diheptanoyl-PI (racemic as well as D and L forms), and 2-methoxy inositol-substituted diheptanoyl-PI, have been synthesized, characterized, and used to investigate key mechanistic questions about phosphatidylinositol-specific phospholipase C (PI-PLC) from Bacillus thuringiensis. Key results include the following: (i) bacterial PI-PLC exhibits a 5-6-fold "interfacial activation" when its substrate is present in an interface as opposed to existing as a monomer in solution (in fact, the similarity to the activation observed with nonspecific PLC enzymes suggests a similarity in activation mechanisms); (ii) the 2-OH must be free since the enzyme cannot hydrolyze diheptanoyl-2-O-methyl-PI (this is most consistent with the formation of inositol cyclic 1,2-phosphate as a necessary step in catalysis); (iii) the inositol ring must have the D stereochemistry (the L-inositol attached to the lipid moiety is neither a substrate nor an inhibitor); and (iv) the presence of noninhibitory L-PI with the D-PI substrate relieves the diacylglycerol product inhibition detected at approximately 30% hydrolysis.     

Potential NDVI as a baseline for monitoring ecosystem functioning

Baseline data are needed to determine the overall magnitude and direction of change in ecosystem functioning. This letter presents an approach to estimate potential NDVI from environmental variables and training data of actual NDVI in nature reserves. Patterns of deviations of actual NDVI from the baseline generally correspond with land-use types in the western United States.     

Band gap opening in methane intercalated graphene

Recent experimental work has demonstrated production of quasi-free-standing graphene by methane intercalation. The intercalation weakens the coupling of adjacent graphene layers and yields Dirac fermion behaviour of monolayer graphene. We have investigated the electronic characteristics of a methane intercepted graphene bilayer under a perpendicularly applied electric field. Evolution of the band structure of intercalated graphene as a function of the bias is studied by means of density-functional theory including interlayer van der Waals interactions. The implications of controllable band gap opening in methane-intercalated graphene for future device applications are discussed.     

High prevalence of mutations in the microtubule-associated protein tau in a population study of frontotemporal dementia in the Netherlands

We report here the large-scale purification of vacuolar (V0V1)-type Na+-ATPase from Enterococcus hirae achieved using column anion-exchange and gel filtration chromatographies; 32 mg of purified enzyme comprising nine subunits, A, B, C, D, E, F, G, I, and K, was obtained from 20 liter culture. This amount is 500-fold larger than that reported in the previous paper [Murata, T., Takase, K., Yamato, I., Igarashi, K., and Kakinuma, Y. (1997) J. Biol. Chem. 272, 24885-24890]. The purified enzyme shows a high specific activity of ATP hydrolysis (35.7 micromol Pi released/min/mg protein). ATP-driven 22Na+ uptake by reconstituted V0V1-proteoliposomes exhibited an apparent Kt value for Na+ of 40 microM, which is near the Km value (20 microM) for Na+ of the ATP hydrolytic activity. Denatured gel electrophoresis revealed that six subunits, A, B, C, D, E, and F, are releasable as the V1 subunit from the V0V1 complex by incubation with ethylenediaminetetraacetic acid; subunit G was not identified. The remaining V0-liposomes containing I and K subunits catalyzed Na+ uptake in response to potassium diffusion potential (Deltapsi, inside negative); the Kt value for Na+ of this reaction was estimated to be about 2 mM. Inhibition by N,N'-dicyclohexylcarbodiimide (DCCD) of the Na+-ATPase activity and Deltapsi-driven Na+ uptake by the V0-liposomes was prevented by the presence of Na+, suggesting that the Na+ binding site overlaps with the DCCD-reactive site.     

Localization of human BRCA1 and its loss in high-grade, non-inherited breast carcinomas

Although the link between the BRCA1 tumour-suppressor gene and hereditary breast and ovarian cancer is established, the role, if any, of BRCA1 in non-familial cancers is unclear. BRCA1 mutations are rare in sporadic cancers, but loss of BRCA1 resulting from reduced expression or incorrect subcellular localization is postulated to be important in non-familial breast and ovarian cancers. Epigenetic loss, however, has not received general acceptance due to controversy regarding the subcellular localization of BRCA1 proteins, reports of which have ranged from exclusively nuclear, to conditionally nuclear, to the ER/golgi, to cytoplasmic invaginations into the nucleus. In an attempt to resolve this issue, we have comprehensively characterized 19 anti-BRCA1 antibodies. These reagents detect a 220-kD protein localized in discrete nuclear foci in all epithelial cell lines, including those derived from breast malignancies. Immunohistochemical staining of human breast specimens also revealed BRCA1 nuclear foci in benign breast, invasive lobular cancers and low-grade ductal carcinomas. Conversely, BRCA1 expression was reduced or undetectable in the majority of high-grade, ductal carcinomas, suggesting that absence of BRCA1 may contribute to the pathogenesis of a significant percentage of sporadic breast cancers.     

The effects of ethanol on a measure of conditioned fear in mice

To develop an efficient topical delivery system for piroxicam using poloxamer gel formulation, physicochemical behavior of piroxicam in poloxamer was studied. The gelling property of poloxamer and the solubility of piroxicam in the poloxamer were investigated. The interaction between piroxicam and poloxamer was studied by x-ray diffractometry (XRD), infrared (IR) spectroscopy and differential thermal analysis (DTA) with a solid dispersion, coprecipitate, or physical mixture. Poloxamer 407 solutions showed the property of a gel when the concentration was higher than 15% (w/w) and poloxamer 407 increased the aqueous solubility of piroxicam by about 11-fold at the concentration of 22.5% (w/w). The results of XRD did not show the crystalline from of piroxicam in the solid dispersion and results of IR spectroscopic analysis showed an association between functional groups of piroxicam and poloxamer.