Venue-Mediated Weak Ties in Multiplex HIV Transmission Risk Networks Among Drug-Using Male Sex Workers and Associates

Objectives. We investigated the structural characteristics of a multiplex HIV transmission risk network of drug-using male sex workers and their associates.Methods. Using a sample of 387 drug-using male sex workers and their male and female associates in Houston, Texas, we estimated an exponential random graph model to examine the venue-mediated relationships between individuals, the structural characteristics of relationships not linked to social venues, and homophily. We collected data in 2003 to 2004. The network comprised social, sexual, and drug-using relationships and affiliations with social venues.Results. Individuals affiliated with the same social venues, bars, or street intersections were more likely to have nonreciprocated (weak) ties with others. Sex workers were less likely than were other associates to have reciprocated (strong) ties to other sex workers with the same venues. Individuals tended to have reciprocated ties not linked to venues. Partner choice tended to be predicated on homophily.Conclusions. Social venues may provide a milieu for forming weak ties in HIV transmission risk networks centered on male sex workers, which may foster the efficient diffusion of prevention messages as diverse information is obtained and information redundancy is avoided.Sex work increases the risk of contracting and transmitting HIV and other sexually transmitted infections through unprotected sexual behaviors or substance use.1 Male sex workers (MSWs) experience high rates of HIV infection, both globally and domestically.2–4 In North America, HIV prevalence among MSWs is estimated to range from 5% to 31%.4 MSWs have high rates of risky sexual behavior and substance use, including drug injection.5–7 However, public health issues related to MSWs have been understudied, and current HIV prevention programs underserve MSWs.4MSWs are not homogeneous nor are the contexts of male sex work uniform.4,8 Because male sex work takes diverse forms in a variety of contexts,8,9 HIV risks may also vary by context. MSWs who solicit sex on the streets are at high risk for HIV infection, and the context of the street may increase the risk. MSWs working in street venues are more likely to have few financial resources, be undereducated, live in unstable housing or on the streets, be unemployed or disabled, and engage in sex work as a means of survival.8 Numerous MSWs and their clients self-identify as heterosexual.10 Men who have sex with men and women (MSMW) have higher rates of both transactional sex and concurrent illicit drug use and sex than do men who have sex with men only, and, among MSMW, both transactional sex and concurrent illicit drug use predict risky sexual behavior.11Although sociodemographic characteristics, HIV infection, and risk behaviors of MSWs have been documented,12,13 relatively few studies have provided a relational account of HIV risk within male sex work networks. It is known, for example, that networks of MSWs are connected to networks of other high-risk groups.2,8,10,14,15 Through these network ties, MSWs may bridge with men who have sex with men (MSM), female sex workers, drug users, and other less risky groups.2,16 MSMW are more likely to engage in sex for drugs or money than are other MSM, and MSMW occupy a central position in the network of HIV-infected males.17 However, because of the diversity of male sex work, it may be inappropriate to conceptualize MSWs as a core group.18Social networks are the structures within which norms are developed and implemented and social support occurs.19,20 Most risk-potential linkages within networks are social,20 and sex ties are often formed through social circles.21 MSWs form unique social networks,9,22 most likely involving risky drug-use and sexual behaviors. The networks are often hierarchical structures in which network leaders control areas for soliciting sex, and the network structure provides mutual support for soliciting sex.9Rarely do studies on HIV risk networks that involve MSWs regard the network as composed of “persons, places, and the relevant links connecting them.”23^(p684) Social venues are an important part of the network structure, forming the setting for MSWs’ social life and facilitating the formation of “sexual affiliation networks.”24 Our previous study25 underscored the duality of people and places26 by focusing on affiliation networks between MSWs and social venues. We found centralized affiliation patterns around a small number of highly interdependent venues. Although interdependent, the venues presented distinct patterns of venue-based clustering.25 These findings, however, were limited because the study focused on venue affiliation. Non–venue-based direct ties also may be important because they are expected to occur within social, drug-using, and sexual relationships. These types of relationships may have different emotional and interpersonal contexts27 that would tend to result in different patterns and types of ties.We defined a multiplex transmission risk network as composed of multifaceted social contexts that comprise a mix of social, sexual, and drug-using ties and affiliation ties to social venues. The social network perspective informs relational mechanisms of information diffusion and social influence at the entire network and personal network levels. Granovettor’s theory of the strength of weak ties posits, “The weak tie between ego and his acquaintance, therefore, becomes not merely a trivial acquaintance tie but rather a crucial bridge between the two densely knit clumps of close friends.”28^(p202) Weak ties avoid information redundancy by enabling individuals to access diverse information and to facilitate the diffusion of information throughout the entire network.29 Although weak ties facilitate information diffusion, they may not be sufficiently powerful to change behavior because of the ties’ transient and passive nature.Rarely have network studies focused on the role that affiliation ties play in forming direct ties between individuals. We defined venue-mediated weak or strong ties as 1-mode social, sexual, and drug-using ties formed through jointly affiliating in the same venues. We examined and statistically tested local relational features of venue-mediated weak or strong ties among MSWs and their associates. On the basis of the effect of bar-based social influence interventions led by opinion leaders on HIV risk reduction,30,31 HIV prevention messages disseminated within venues are expected to facilitate the diffusion of information, and, thus, weak ties are more likely than are strong ties to be observed linked to social venues.In personal networks, reciprocated ties suggest higher levels of trust and intimacy and, in some cases, a strong tendency to engage in risky behaviors.32 The risk of engaging in behaviors that transmit HIV are also heightened during sex for money exchanges, particularly if there is a strong economic incentive for doing so. This suggests that risk is related to the multiple types of ties determined by context. Additionally, homophily affects network ties by influencing the information that people receive, the attitudes formed, and the social interactions experienced.33 We also sought to examine the tendency of reciprocity and the effect of homophily on HIV status and sociodemographic and behavioral factors when forming risk-potential relationships that comprise social, sexual, or drug-using ties but are not linked to social venues. The likelihood of engaging in risk-taking behavior is greater in relationships with a high degree of homophily, as information flows and persuasion tend to be more frequent among like pairs.32 We tested these relational features using a stochastic network modeling approach.     

Factors relating to the conditions and characteristics of mental health among the inhabitants in a methylmercury polluted area

OBJECTIVES: Little attention has been paid to mental health of inhabitants of methylmercury-polluted areas. The objective of this study was to examine the factors relating to the conditions and characteristics of mental health of inhabitants residing in a methylmercury-polluted area. METHODS: The eligible subjects of the study were inhabitants over the age of 40 years (n=301) living in two fishing village districts that were polluted by high concentrations of methylmercury. The study was conducted in two phases. In the first phase, a structured questionnaire was used to gather information on the current health condition and experience with Minamata disease of each subject through interviews. In the second phase, the General Health Questionnaire (GHQ)-30 was distributed to measure the psychological distress of the respondents. RESULTS: There were 133 (44.2%) study subjects. Factor analysis of the data collected using the GHQ was carried out and five factors that accounted for 57.9% of the total variance were selected. The first factor was labeled "depression and anxiety". Depression and anxiety were significantly associated with self-rated health status, the number of subjective symptoms, monthly outpatient visits and the receipt of compensation. Covariance structure analysis using the Amos 4.0 program demonstrated that depression and anxiety were significantly associated with the subjects' health condition, which in turn was influenced by experience with Minamata disease. CONCLUSION: Depression and anxiety of the inhabitants may be directly caused by the health condition. Further investigations with more precise and detailed measurements are needed to corroborate the causal relationship.     

Exploration of Antiemetics for Osteoporosis Therapy-Induced Nausea and Vomiting Using PET Molecular Imaging Analysis to Gastrointestinal Pharmacokinetics

Purpose

To select appropriate antiemetics relieving teriparatide-induced nausea and vomiting during osteoporosis treatment using PET molecular imaging and pharmacokinetic analysis.

Methods

Rats were pretreated with subcutaneous teriparatide, followed by oral administration of antiemetics with different pharmacological effects. The pharmacokinetics of antiemetics were assessed by oral administration of 2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG) under free moving conditions in vivo. The effect of teriparatide on the permeability of Caco-2 cell membranes to [¹⁸F]FDG was assessed in vitro. The effects of antiemetics on teriparatide-induced suppression of gastrointestinal motility in vivo was assayed by positron emission tomography (PET) using orally administered [¹⁸F]FDG.

Results

Teriparatide delayed the time-radioactivity profile of [¹⁸F]FDG in blood and significantly reduced its absorption rate constant (k _a ), determined from non-compartmental analysis, to 60% of control. In contrast, co-administration of granisetron or mosapride restored the time-radioactivity profile and k _a of [¹⁸F]FDG to control levels. Teriparatide had no effect on Caco-2 membrane permeability to [¹⁸F]FDG. Pharmacokinetic PET imaging data analysis quantitatively showed the pharmacological effects of teriparatide-induced suppression of upper gastrointestinal motility and its restoration by granisetron and mosapride.

Conclusions

Teriparatide-induced abdominal discomfort might be attributed to GI motility, and PET imaging analysis is a useful tool to for the selection of appropriate antiemetics.

     

High levels of stearic acid,palmitoleic acid,and dihomo-γ-linolenic acid and low levels of linoleic acid in serum cholesterol ester are associated with high insulin resistance

The association of fatty acid composition with insulin resistance and type 2 diabetes has been reported in Western populations, but there is limited evidence of this association among the Japanese, whose populace consume large amounts of fish. To test the hypothesis that high palmitic, palmitoleic, and dihomo-γ-linolenic acids and low levels of linoleic and n-3 fatty acids are associated with higher insulin resistance among the Japanese, the authors investigated the relationship between serum fatty acid composition and serum C-peptide concentrations in 437 Japanese employees aged 21 to 67 years who participated in a workplace health examination. Serum cholesterol ester and phospholipid fatty acid compositions were measured by gas-liquid chromatography. Desaturase activity was estimated by fatty acid product-to-precursor ratios. A multiple regression was used to assess the association between fatty acid and C-peptide concentrations. C-peptide concentrations were associated inversely with linoleic acid levels in cholesterol ester and phospholipid (P for trend = .01 and .02, respectively) and positively with stearic and palmitoleic acids in cholesterol ester (P for trend =.02 and .006, respectively) and dihomo-γ-linolenic acid in cholesterol ester and phospholipid (P for trend < .0001 for both). C-peptide concentrations were not associated with n-3 polyunsaturated fatty acids. C-peptide concentrations significantly increased as δ-9-desaturase (16:1 n-7/16:0) and δ-6-desaturase (18:3 n-6/18:2 n-6) increased (P for trend = .01 and .03, respectively) and δ-5-desaturase (20:4 n-6/20:3 n-6) decreased (P for trend = .004). In conclusion, a fatty acid pattern with high levels of serum stearic, palmitoleic, or dihomo-γ-linolenic acids; δ-9-desaturase (16:1 n-7/16:0) or δ-6-desaturase (18:3 n-6/18:2 n-6) activities; and low levels of serum linoleic acid or δ-5-desaturase (20:4 n-6/20:3 n-6) activity might be associated with higher insulin resistance in Japanese adults.     

Effect of glimepiride and glibenclamide on S-warfarin 7-hydroxylation by human liver microsomes, recombinant human CYP2C9.1 and CYP2C9.3

The effect of glimepiride on metabolism of S-warfarin to 7-hydroxywarfarin was studied using human liver microsomes and recombinant cytochrome P450 2C9 microsomes (CYP2C9.1 and CYP2C9.3), and was compared with the results from the experiments using glibenclamide as an inhibitor. S-Warfarin 7-hydroxylation by recombinant CYP2C9.1 and CYP2C9.3 was inhibited by glimepiride competitively. The apparent K(i) value of glimepiride was lower at CYP2C9.3 than at CYP2C9.1. Glimepiride also inhibited 7-hydroxylation of S-warfarin in a competitive manner by microsomes from human liver which showed the genotypes of CYP2C9, as CYP2C9*1/*1 or CYP2C9*1/*3. The apparent K(i) value of glimepiride was lower than that of glibenclamide. These results may provide valuable information for optimizing the anticoagulant activity of warfarin when glimepiride is co-administered to patients.     

Effects of Transfection with the Cu,Zn-Superoxide Dismutase Gene on Xanthine/Xanthine Oxidase-Induced Cytotoxicity in Fibroblasts from Rat Skin

Purpose. The effects of transfection with the human Cu, Zn-superoxide dismutase (hSOD)⁴ gene on active oxygen-induced cytotoxicity in rat skin fibroblasts (FR) were studied for the purpose of developing the novel delivery system of hSOD using hSOD gene. Methods. An expression plasmid for hSOD, pRc/RSV-SOD, was constructed and used to transfect FR cells. Xanthine (X)/xanthine oxidase (XO) system were used to generate active oxygen species. The effects of transfection with the hSOD gene on active oxygen-induced cytotoxicity were assessed by comparing the number of surviving cells and the level of lipid peroxidation in host and transformants after exposure to X/XO system. Results. The cellular SOD activity in RSV-SOD cells transfected with pRc/RSV-SOD was significantly increased in comparison with host or RSV cells transfected with the pRc/RSV plasmid containing no hSOD gene as a control. Furthermore, Western blot analysis using an anti-hSOD antibody indicated the production of hSOD in RSV-SOD cells. On the other hand, although the numbers of surviving cells in both host and RSV-SOD cultures after exposure to X/XO system decreased in a time-dependent manner, the decrease in number of surviving RSV-SOD cells was less than that in host cells. In the presence of catalase, the decreases in number of surviving cells in both host and RSV-SOD cultures after exposure to the X/XO system were also less than those in the absence of catalase. However, the decreases in cell survival in RSV-SOD cultures were significantly less than those in host cells in the presence of catalase. Furthermore, the levels of lipid peroxidation in RSV-SOD cells exposed to the X/XO system in the presence or absence of catalase were lower than those in host cells. These results indicated that the increase in cellular SOD activity by transfection with the hSOD gene protects cells from oxidative stress. Conclusions. Human SOD gene therapy may be useful for treatment of diseases in which oxidative tissue damage is produced.     

Differences in the priming effect of various clades/subclades of inactivated H5N1 vaccine for booster injection with heterologous clades of vaccine strains

The prime-boost response induced by different combinations of four H5N1 vaccines (NIBRG-14 (clade 1), Indo05/2005(H5N1)/PR8-IBCDC-RG2 (clade 2.1), A/Bar-Headed Goose/Qinhai Lake/1A/05 SJ163222 (clade 2.2), and Anhui01/2005(H5N1)-PR8-IBCDC-RG5 (clade 2.3.4)) was evaluated in mice. Clade 1-primed BALB/c mice showed a booster response to all of the other three H5N1 vaccines. Clade 2.2 vaccine was also a good priming vaccine. However, mice primed with clade 2.1 or clade 2.3.4 vaccine did not respond to booster injection with clade 1 vaccine, suggesting that priming might actually inhibit the booster response with some combinations of vaccines belonging to different clades. Analysis of the mechanism involved showed that lymphocytes from primed mice secreted comparable amounts of cytokines with any combination of priming and booster vaccines. Therefore, impairment of B cell immunity specific to certain booster strains may have been involved.     

Mapping of A gene responsible for cataract formation and its modifier in the UPL rat

PURPOSE: The Upjohn Pharmaceuticals Limited (UPL) rat is a unique model for cataracts, which are inherited as an autosomal semidominant trait and expressed as early-onset (E-type) cataracts in homozygotes and as late-onset (L-type) cataracts in heterozygotes. In this study, a gene and its modifier, which are responsible for formation of cataract, were mapped. METHODS: Fifty-five BN x (BN x UPL)F(1) backcross rats and 133 BN x UPL intercross rats were produced. The cataracts present in the rats at eye opening were diagnosed as E-type. Cataracts that developed after eye opening were diagnosed as L-type, and the ages when complete opacity in the lens was observed were used as a quantitative trait to map a gene that modifies the development of mature cataracts. Linkage analysis was performed using 64 arbitrarily primed-representational difference analysis (AP-RDA) markers and 74 microsatellite markers. RESULTS: A gene responsible for the formation of cataract was mapped to the vicinity of D2Rat134 on rat chromosome (chr) 2. A candidate gene, connexin 50 (Cx50/Gja8), had a C-to-T transition at codon 340 that is predicted to result in a nonconservative substitution of arginine by tryptophan. Recombination in the Cx50 genotype and formation of cataract was not observed. By quantitative trait loci analysis, a gene that modified the age of the development of mature cataract was mapped on rat chr 5. CONCLUSIONS: A candidate gene for formation of cataracts in UPL rats was mapped to rat chr 2, and the Cx50 gene was a strong candidate. In addition, a potential modifier gene was mapped on chr 5. Future cloning of these genes will provide good targets for new therapies that can delay the progression of cataracts.     

Preventive effect of a second-generation silicone intraocular lens on posterior capsule opacification

PURPOSE: To compare the preventive effect of a second-generation silicone intraocular lens (IOL) on posterior capsule opacification (PCO) with that of a soft acrylic IOL. SETTING: Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. METHODS: After phacoemulsification, a silicone IOL (PhacoFlex II) was implanted in 1 eye and an acrylic IOL (AcrySof) in the contralateral eye of 5 rabbits. RESULTS: The posterior view 3 weeks after surgery showed slightly more PCO in 3 eyes with the PhacoFlex II lens than in eyes with the AcrySof IOL, with the PCO obscuring the iris structures. In 2 eyes with an AcrySof IOL, slightly more PCO was seen. Histopathological examination revealed that a bend and complex folds in the posterior capsule were formed with both the PhacoFlex II and AcrySof IOLs. However, the capsular bend formed by the PhacoFlex II lens, which was caused by its blunt edge, was not as sharp as that with the AcrySof IOL and more PCO was seen in all eyes with a PhacoFlex II lens. CONCLUSIONS: Capsular bend formation does not necessarily require a sharp optic edge. A truncated optic rim of a certain thickness appears to form a bend. The capsule-bending does not appear to be an all-or-nothing effect. There seems to be a transition. That a capsular bend forms despite a blunt rather than a sharp optic edge may explain why the second-generation PhacoFlex II IOL prevents PCO better than first-generation and PMMA IOLs.