Factors associated with changes in sex behaviour among drug users in Puerto Rico

Despite available strategies to prevent sex risk behaviours in Puerto Rico, heterosexual transmission of HIV continues to increase. Since 1990, heterosexual contact has been the fastest growing infection risk category among the island's general population, and the primary transmission route for women and children. To understand change in sex risk behaviours and factors related to change, 911 drug injectors and 359 crack smokers were recruited from the San Juan metropolitan area following a stratified cluster design. This study comprised a total of 1,004 (79.1%) drug users who were assessed at follow-up. Abstinence from sex behaviour increased from 54.6% to 61.1% (p < 0.01), use of condoms during vaginal sex also increased from 26.4% to 36.9% (p < 0.01). In multivariate analysis, significant predictors of abstinence were gender, injection drug use, HIV seropositivity and not having a steady partner. Predictors of using condoms during vaginal sex were HIV seropositivity, STD diagnosis and participation in an HIV preventive programme. These findings indicate that additional HIV preventive efforts are needed to reduce sex risk behaviours among drug users who have a steady sex partner, as well as among drug users who are HIV-negative.

Risk behaviors, HIV seropositivity, and tuberculosis infection in injecting drug users who operate shooting galleries in Puerto Rico

This study was designed to assess HIV risk behaviors, HIV seroprevalence, and tuberculosis (TB) infection in shooting gallery managers in Puerto Rico. The subjects were 464 injection drug users (IDUs), of whom 12.5% reported managing shooting galleries. The median frequency of drug injection was higher in shooting gallery managers than in nonmanagers. A trend was observed for purified protein derivative (PPD) reactivity to increase according to the length of time spent as a gallery manager, but this trend was not statistically significant. However, anergy rates increased significantly with increase in the number of months spent as shooting gallery manager (p = .021). Multivariate analyses showed that IDUs reporting shooting gallery management experience of > or = 25 months were more likely to be infected with HIV. Prevention programs need to emphasize strategies to protect the health of shooting gallery clients and, in particular, shooting gallery managers. Additional studies are required to determine effective strategies for reducing the risk of HIV and TB infection in shooting galleries.

ras transformation is associated with decreased expression of the brm/SNF2alpha ATPase from the mammalian SWI-SNF complex

The brm and BRG-1 proteins are mutually exclusive subunits of the mammalian SWI-SNF complex. Within this complex, they provide the ATPase activity necessary for transcriptional regulation by nucleosome disruption. Both proteins were recently found to interact with the p105Rb tumor suppressor gene product, suggesting a role for the mammalian SWI-SNF complex in the control of cell growth. We show here that the expression of brm, but not BRG-1, is negatively regulated by mitogenic stimulation, and that growth arrest of mouse fibroblasts leads to increased accumulation of the brm protein. The expression of this protein is also down-regulated upon transformation by the ras oncogene. Re-introduction of brm into ras transformed cells leads to partial reversion of the transformed phenotype by a mechanism that depends on the ATPase domain of the protein. Our data suggest that increased levels of brm protein favour the withdrawal of the cell from the cycle whereas decreased expression of the brm gene may facilitate cellular transformation by various oncogenes.

Correlation of the suppressive activity of a biological response modifier on the proliferation of peripheral blood mononuclear cells and the reduction of HIV titer

Activation of CD4+ cells is a prerequisite for infection by the human immunodeficiency virus (HIV). Thus, any agent capable of suppressing CD4+ cell proliferation could create a refractory stage that would impede viral infection. We have reported, in a previous publication, that a biological response modifier (BRM), polyantigenic immunomodulator (PAI) substantially reduces HIV-1 titer (from 20 to 100%) in peripheral mononuclear cells (PBMC) cultures with high viral titer (p24 = 10(2)-10(5) pg/ml). We are presenting data suggesting that the reported reduction in virus titer seems to be associated with a suppressive activity of PAI on the proliferation of PBMC from intravenous drug users (IVDU) infected and non-infected with HIV-1. PAI, a well characterized BRM, is a mixture of inactivated bacterial and influenza virus vaccines. PBMC from healthy donors and IVDU individuals were exposed to PAI, phytohemagglutinin (PHA), interleukin-2 (IL-2) and to combinations of PAI with either PHA or IL-2. Appropriate controls were included. 3H-thymidine pulsing was used as indicator of cell proliferation. The stimulation index and the difference between mean cpm of test sample and control were used to measure proliferative activity. There was a low proliferative response in the PBMC cultures from IVDU and HIV-1 positive patients, but it was substantially lower in the later group. When PBMC cultures from the same group of individuals were exposed to PAI, PHA and IL-2, and to the combination of either PAI plus PHA or IL-2, the response observed in the PAI treated group was uniformly lower than in the other treated cultures. Moreover, when PAI was combined with PHA, it exerted a significant reduction in the measured parameters. The effect of PAI on IL-2 activity was negligible. A suppressive effect of a PAI has been detected on the proliferation of PBMC from IVDA and HIV-1 positive individuals. This activity may be associated with the capacity of PAI to reduce HIV titers in infected PBMC cultures.

Components of the human SWI/SNF complex are enriched in active chromatin and are associated with the nuclear matrix

Biochemical and genetic evidence suggest that the SWI/SNF complex is involved in the remodeling of chromatin during gene activation. We have used antibodies specific against three human subunits of this complex to study its subnuclear localization, as well as its potential association with active chromatin and the nuclear skeleton. Immunofluorescence studies revealed a punctate nuclear labeling pattern that was excluded from the nucleoli and from regions of condensed chromatin. Dual labeling failed to reveal significant colocalization of BRG1 or hBRM proteins with RNA polymerase II or with nuclear speckles involved in splicing. Chromatin fractionation experiments showed that both soluble and insoluble active chromatin are enriched in the hSWI/SNF proteins as compared with bulk chromatin. hSWI/SNF proteins were also found to be associated with the nuclear matrix or nuclear scaffold, suggesting that a fraction of the hSWI/SNF complex could be involved in the chromatin organization properties associated with matrix attachment regions.

Transcription of glutamine synthetase genes (glnA and glnN) from the cyanobacterium Synechocystis sp. strain PCC 6803 is differently regulated in response to nitrogen availability

In the cyanobacterium Synechocystis sp. strain PCC 6803 we have previously reported the presence of two different proteins with glutamine synthetase activity: GSI, encoded by the glnA gene, and GSIII, encoded by the glnN gene. In this work we show that expression of both the glnA and glnN genes is subjected to transcriptional regulation in response to changes in nitrogen availability. Northern blot experiments and transcriptional fusions demonstrated that the glnA gene is highly transcribed in nitrate- or ammonium-grown cells and exhibits two- to fourfold-higher expression in nitrogen-starved cells. In contrast, the glnN gene is highly expressed only under nitrogen deficiency. Half-lives of both mRNAs, calculated after addition of rifampin or ammonium to nitrogen-starved cells, were not significantly different (2.5 or 3.4 min, respectively, for glnA mRNA; 1.9 or 1.4 min, respectively, for glnN mRNA), suggesting that changes in transcript stability are not involved in the regulation of the expression of both genes. Deletions of the glnA and glnN upstream regions were used to delimit the promoter and the regulatory sequences of both genes. Primer extension analysis showed that structure of the glnA gene promoter resembles those of the NtcA-regulated promoters. In addition, mobility shift assays demonstrated that purified, Escherichia coli-expressed Synechocystis NtcA protein binds to the promoter of the glnA gene. Primer extension also revealed the existence of a sequence related to the NtcA binding site upstream from the glnN promoter. However, E. coli-expressed NtcA failed to bind to this site. These findings suggest that an additional modification of NtcA or an additional factor is required for the regulation of glnN gene expression.

Purification and characterization of a new type of glutamine synthetase from cyanobacteria

The cyanobacterium Synechocystis sp. PCC 6803 contains two genes encoding two different types of glutamine synthetases (GS), glnA and glnN. The first codes for a typical prokaryotic GS type I and the second one codes for a GS type III, different in amino acid sequence to the prokaryotic GSI and the eukaryotic GSII. The glnN gene has been expressed in Escherichia coli and the corresponding protein purified almost to homogeneity (92%). The native enzyme (500 kDa) was composed of six identical subunits with an apparent molecular mass of 80 kDa. The protein was strongly stabilized in the presence of Mn2+ but not with other divalent cations. Biosynthetic activity of GSIII required the same substrates and cofactors as GSI and GSII enzymes. Apparent Km values for ATP, glutamate and ammonium were 0.43 mM, 0.9 mM and 0.19 mM, respectively. The enzyme was weakly inhibited by several amino acids and strongly inhibited by ADP. Synechocystis GSIII was also inhibited by L-methionine sulfoximine and DL-phosphinotricin, two transition-state analogs of the GS reaction mechanism. GSIII has also been purified from nitrogen-starved Synechocystis 6803 glnA mutant cells, demonstrating that the GS activity, strongly induced under nitrogen starvation in these cells, corresponds to the glnN gene product. In addition, a Synechocystis 6803 glnN mutant lacks the corresponding 80-kDa protein (GSIII). Polyclonal antibodies specific for GSIII cross-react with GSIII from other cyanobacteria. In all the strains analysed, levels of GSIII protein increased under nitrogen deficiency. These data suggest that GSIII is specifically required under conditions of nitrogen starvation.

Behavioral effects of receiving HIV test results among injecting drug users in Puerto Rico

OBJECTIVES

To examine the influence of knowledge of HIV serostatus on changes in risk behaviors among injecting drug users (IDU).

PROCEDURES

IDU were recruited through sampling conducted at street drug-selling areas. Of 374 participants, 88.8% consented to be HIV tested and returned for their test results, and 73.5% were relocated and interviewed 6 months later.

RESULTS

Of the 176 IDU who reported a seronegative test result prior to baseline, 29 tested seropositive at baseline. No significant differences were found between HIV-positive and HIV-negative IDU in needle risk behaviors. HIV-positive IDU were significantly less likely to report being sexually active [odds ratio (OR), 0.41 : 95% confidence interval (CI), 0.22-0.75] and more likely to use condoms during vaginal (OR, 4.43; 95% CI, 1.48-13.29) and oral sex (OR, 6.67; 95% CI, 1.42-31.33).

CONCLUSION

The findings of this study show the importance of encouraging IDU to undergo periodic retesting. HIV testing could have an important role in reducing heterosexual transmission from IDU.

Risk factors for shooting gallery use among drug injectors in Puerto Rico

Needle sharing is one of the principal risk behaviors leading to HIV transmission among injection drug users (IDUs). Shooting galleries, a social context where IDUs rent, share, and borrow needles, are locations usually found near drug markets. This study, which interviewed 1,700 IDUs from May 1989 to June 1990, assesses sociodemographic characteristics and HIV risk behaviors among shooting gallery users in Puerto Rico. Multivariate analyses showed that shooting gallery use is associated with speedball (a concoction of heroin and cocaine) injection, income from illegal activities and previous drug treatment. Shooting gallery users were more likely to rent, share, and borrow needles, and less likely to always use bleach and water to clean needles. Strategies to reduce shooting gallery use among drug injectors are discussed.

Mycobacterium tuberculosis infection among crack and injection drug users in San Juan, Puerto Rico

This study aims to determine the prevalence of Mycobacterium tuberculosis infection and its association with HIV and other health risk factors among drug users. A sample of 716 IDUs and crack users were enrolled from community sites. Consenting subjects were tested for HIV serum antibody status. Drug users with an unknown PPD status were administered a PPD skin test and an anergy panel of three antigens (Candida, mumps and tetanus). Overall, 68 (10.3%) were reactive to the PPD skin test, 240 (34.7%) were HIV positive and 195 (29.5%) showed cutaneous anergy. Participants infected with tuberculosis (TB) were more likely to be HIV seropositive, and to have a history of incarceration and residential drug treatment than those not infected. In addition, TB infection was more prevalent among intravenous drug users (IDUs) and shooting gallery managers. These findings suggest that drug users should be considered at high risk for TB and HIV infection. Innovative programs to monitor both infections among drug users are needed to arrest what can become a dual epidemic of HIV and TB in the near future.

The hbrm and BRG-1 proteins, components of the human SNF/SWI complex, are phosphorylated and excluded from the condensed chromosomes during mitosis

In yeast, the SNF/SWI complex is believed to regulate transcription by locally altering the chromatin structure. At the present time, three human homologues of yeast SNF/SWI proteins have been characterized: hbrm and BRG-1, homologues of SNF2/SWI2, and hSNF5, a homologue of SNF5. We show here that, during mitosis, hbrm and BRG-1 are phosphorylated and excluded from the condensed chromosomes. In this phase of the cell cycle, the level of hbrm protein is also strongly reduced, whereas the level of BRG-1 remains constant. The mitotic phosphorylation of hbrm and BRG-1 is found not to disrupt the association of these proteins with hSNF5 but correlates with a decreased affinity for the nuclear structure in early M phase. We suggest that chromosomal exclusion of the human SNF/SWI complex at the G2-M transition could be part of the mechanism leading to transcriptional arrest during mitosis.

The NADP+-isocitrate dehydrogenase gene (icd) is nitrogen regulated in cyanobacteria

NADP+-isocitrate dehydrogenase (NADP+-IDH) activity and protein levels in crude extracts from the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 and the filamentous, dinitrogen-fixing Anabaena sp. strain PCC 7120 were determined under different nitrogen conditions. The highest NADP+-IDH activity and protein accumulation were found under dinitrogen-fixing conditions for the Anabaena strain and under nitrogen starvation for Synechocystis sp. PCC 6803. The icd gene that encodes the NADP+-IDH from Synechocystis sp. strain PCC 6803 was cloned by heterologous hybridization with the previously isolated icd gene from Anabaena sp. strain PCC 7120. The two cyanobacterial icd genes show 81% sequence identity and share a typical 44-amino-acid region different from all the other icd genes sequenced so far. The icd gene seems to be essential for Synechocystis growth since attempts to generate a completely segregated icd mutant were unsuccessful. Transcripts of 2.0 and 1.6 kb were detected by Northern (RNA) blot analysis, for the Anabaena and Synecho-cystis icd genes, respectively. Maximal icd mRNA accumulation was reached after 5 It of nitrogen starvation in Synechocystis cells and under dinitrogen-fixing conditions in Anabaena cells. Primer extension analysis showed that the structure of the Synechocystis icd gene promoter resembles those of the NtcA-regulated promoters. In addition, mobility shift assays demonstrated that purified Synechocystis NtcA protein binds to the promoter of the icd gene. All these data suggest that the expression of the icd gene from Synechocystis sp. strain PCC 6803 may be subjected to nitrogen control mediated by the positively acting regulatory protein NtcA.

A novel mechanism of glutamine synthetase inactivation by ammonium in the cyanobacterium Synechocystis sp. PCC 6803. Involvement of an inactivating protein

The glutamine synthetase of the cyanobacterium Synechocystis sp. PCC 6803 can be inactivated in vivo by ammonium addition by a new mechanism that involves the binding to the enzyme of an inactivating factor. This binding provokes a different mobility of the inactive enzyme with respect to the active form in non-denaturing PAGE, but not in SDS-PAGE. This modification of glutamine synthetase is for the first time visualized by Western blot analysis of the active and inactive forms. Cross-linking experiments using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) demonstrate the existence of two main complexes of 56 kDa and 67 kDa between the inactivating factor and the glutamine synthetase subunit (53 kDa) in the inactive but not in the active form of glutamine synthetase.

The NADP-glutamate dehydrogenase of the cyanobacterium Synechocystis 6803: cloning, transcriptional analysis and disruption of the gdhA gene

The gdhA gene of Synechocystis PCC 6803, which encodes an NADP-dependent glutamate dehydrogenase (NADP-GDH), has been cloned by complementation of an Escherichia coli glutamate auxotroph. This gene was found to code for a polypeptide of 428 amino acid residues, whose sequence shows high identity with those of archaebacteria (42-47%), some Gram-positive bacteria (40-44%) and mammals (37%). The minimal fragment of Synechocystis DNA required for complementation (2kb) carries the gdhA gene preceded by an open reading frame (ORF2) encoding a polypeptide of 130 amino acids. ORF2 and gdhA are co-transcribed as a 1.9 kb mRNA, but shorter transcripts including only gdhA were also detected. Two promoter regions were identified upon transcriptional fusion to the cat reporter gene of a promoter probe plasmid. Transcription from the promoter upstream of ORF2 was found to be regulated depending on the growth phase of Synechocystis, in parallel to NADP-GDH activity. This promoter is expressed in Escherichia coli too, in contrast to the second promoter, located between ORF2 and gdhA, which was silent in E. coli and did not respond to the stage of growth in Synechocystis. Disruption of the cyanobacterial gdhA gene with a chloramphenicol resistance cassette yielded a mutant strain totally lacking NADP-GDH activity, demonstrating that this gene is not essential to Synechocystis 6803 under our laboratory conditions.

Electron transport controls transcription of the glutamine synthetase gene (glnA) from the cyanobacterium Synechocystis sp. PCC 6803

The glnA gene, encoding type I glutamine synthetase (GS) in Synechocystis sp. PCC 6803, showed a high sequence similarity with other cyanobacterial glnA genes. A dramatic decrease in the amount of glnA mRNA, a single transcript of about 1.6 kb, was observed after transfer to darkness, or after incubation with the electron transport inhibitors DCMU or DBMIB. The levels of glnA transcript were fully recovered after 5 min of reillumination. The glnA mRNA was found to be equally stable both in the light and the dark (half-life about 2.5 min). Unlike the glnA messenger, the amount of GS protein was not reduced in the dark. Synthesis of the glnA transcript in the dark required the presence of glucose. In addition, glnA transcription in a Synechocystis psbE-psbF mutant lacking photosystem II required the presence of glucose even when grown in the light. These observations indicate that glnA transcription is under the control of the redox state of the cell. Finally, nitrogen starvation provoked a delay in the decrease of glnA transcript in darkness, suggesting a connection between nitrogen and redox controls of glnA transcript levels.

A mutant lacking the glutamine synthetase gene (glnA) is impaired in the regulation of the nitrate assimilation system in the cyanobacterium Synechocystis sp. strain PCC 6803

The existence in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 of two genes (glnA and glnN) coding for glutamine synthetase (GS) has been recently reported (J.C. Reyes and F.J. Florencio, J. Bacteriol. 176:1260-1267, 1994). In the current work, the regulation of the nitrate assimilation system was studied with a glnA-disrupted Synechocystis mutant (strain SJCR3) in which the only GS activity is that corresponding to the glnN product. This mutant was unable to grow in ammonium-containing medium because of its very low levels of GS activity. In the SJCR3 strain, nitrate and nitrite reductases were not repressed by ammonium, and short-term ammonium-promoted inhibition of nitrate uptake was impaired. In Synechocystis sp. strain PCC 6803, nitrate seems to act as a true inducer of its assimilation system, in a way similar to that proposed for the dinitrogen-fixing cyanobacteria. A spontaneous derivative strain from SJCR3 (SJCR3.1), was able to grow in ammonium-containing medium and exhibited a fourfold-higher level of GS activity than but the same amount of glnN transcript as its parental strain (SJCR3). Taken together, these finding suggest that SJCR3.1 is a mutant affected in the posttranscriptional regulation of the GS encoded by glnN. This strain recovered regulation by ammonium of nitrate assimilation. SJCR3 cells were completely depleted of intracellular glutamine shortly after addition of ammonium to cells growing with nitrate, while SJCR3.1 cells maintained glutamine levels similar to that reached in the wild-type Synechocystis sp. strain PCC 6803. Our results indicate that metabolic signals that control the nitrate assimilation system in Synechocystis sp. strain PCC 6803 require ammonium metabolism through GS.

A new type of glutamine synthetase in cyanobacteria: the protein encoded by the glnN gene supports nitrogen assimilation in Synechocystis sp. strain PCC 6803

A new glutamine synthetase gene, glnN, which encodes a polypeptide of 724 amino acid residues (M(r), 79,416), has been identified in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803; this is the second gene that encodes a glutamine synthetase (GS) in this cyanobacterium. The functionality of this gene was evidenced by its ability to complement an Escherichia coli glnA mutant and to support Synechocystis growth in a strain whose glnA gene was inactivated by insertional mutagenesis. In this mutant (strain SJCR3), as well as in the wild-type strain, the second GS activity was subject to regulation by the nitrogen source, being strongly enhanced in nitrogen-free medium. Transcriptional fusion of a chloramphenicol acetyltransferase (cat) gene with the 5'-upstream region of glnN suggested that synthesis of the second Synechocystis GS is regulated at the transcriptional level. Furthermore, the level of glnN mRNA, a transcript of about 2,300 bases, was found to be strongly increased in nitrogen-free medium. The glnN product is similar to the GS subunits of Bacteroides fragilis and Butyrivibrio fibrisolvens, two obligate anaerobic bacteria whose GSs are markedly different from other prokaryotic and eukaryotic GSs. However, significant similarity is evident in the five regions which are homologous in all of the GSs so far described. The new GS gene was also found in other cyanobacteria but not in N2-fixing filamentous species.

Effect of Glucose Utilization on Nitrite Excretion by the Unicellular Cyanobacterium Synechocystis sp. Strain PCC 6803

Up to 1 mM nitrite was excreted by Synechocystis strain 6803 cells growing under mixotrophic or photoheterotrophic conditions. This excretion is not due to a lower ratio of nitrite and nitrate reductase activities in the presence of glucose but seems to be related to a shortage of reduced ferredoxin, their electron donor, as a result of a decrease in noncyclic photosynthetic flow observed under these circumstances. Because about 60% of the reduced nitrate is excreted, the potential utilization of cyanobacteria for removal of nitrate from contaminated waters containing high concentrations of organic compounds is questioned.

HIV risk behaviors and HIV seropositivity among young injection drug users

Although injection drug use (IDU) is the major risk category for HIV infection in Puerto Rico and injection drug users start their drug injection careers very young, there is little information related to drug injection patterns of young IDUs. In this paper we report on factors found to be associated with HIV seropositivity among 255 young IDUs (16-24 years old). Overall, 23.5% subjects were HIV seropositive. Being 22 to 24 years old, having dropped out of school, having a history of incarceration, and having been diagnosed with STDs, and initiating drug use injection before 17 years of age were the factors significantly related to HIV seropositivity. Findings suggest that prevention programs should begin early in the development of youngsters. Special HIV and STD preventive programs for youngsters at risk of leaving school before completing high school should be a priority.

Human immunodeficiency virus infection and risk behaviors among injection drug users in four Puerto Rican communities

This study compares the prevalence of human immunodeficiency virus (HIV) infection and HIV risk behaviors among 1,702 injection drug users (IDUs) recruited within four catchment areas in metropolitan San Juan (79.9% male and 20.1% female). To assess the impact of different antecedent variables on intercommunity risk differences, we constructed separate logistic regression models for each one of the catchment areas in the analysis. Old San Juan/Santurce has the highest rate of HIV seropositivity. Furthermore, Old San Juan/Santurce IDUs were more likely to have had incarceration experience, to report using drugs only by injection, and to have been injecting drugs for 16 years or more. Also, this group was more likely to report practicing prostitution and to have been diagnosed with sexually transmitted diseases (STDs) than their peers from the other sites. The need of preventive programs in specific communities within metropolitan urban areas is discussed.

Evidence of poxvirus in dusky dolphin (Lagenorhynchus obscurus) and Burmeister's porpoise (Phocoena spinipinnis) from coastal Peru

In 1990, 74 dusky dolphins (Lagenorhynchus obscurus) and 10 Burmeister's porpoises (Phocoena spinipinnis) were examined for the presence of hyperpigmented marks and pinhole lesions on the skin (tattoo lesions) at the fishing terminal of Pucusana, central Peru. Prevalences of tattoo lesions were 8.1% and 30% in the dolphins and porpoises, respectively. Intracytoplasmic poxviruses were demonstrated by transmission electron microscopy in ultrathin sections of three of eight samples of infected epidermis from both species. The reason for the negative results in others is unclear but may be related to stages of infection with low virus density or even incorrect classification of some lesions as genuine viral tattoos. An irregular arrangement of tubules on the outer viral membrane, similar to those in orthopoxviruses, was visible in negative contrast preparations for P. spinipinnis. This is the first record of poxvirus in porpoises (Phocoenidae) and also the first report for dusky dolphins, and generally for cetaceans of the southern hemisphere.

Behavioral risk factors and human immunodeficiency virus (HIV) prevalence among intravenous drug users in Puerto Rico

This study reports on four empirical models likely to contribute to understanding the behaviors linked with human immunodeficiency virus (HIV) among intravenous drug users. The sample comprises 1,637 intravenous drug users recruited between May 1989 and June 1990 in San Juan, Puerto Rico. Adjusting for sociodemographics, four logistic regression models were constructed to assess the association of risk behaviors with HIV seropositivity. In model 1, the variables found to be significantly associated with HIV seropositivity were injecting four times a day, injection as the only route of consuming drugs, and years of injection. In model 2, the only risk behavior significantly associated with HIV seropositivity was injecting drugs in shooting galleries. In model 3, all sex risk variables failed to meet the adjusted level of significance. In model 4, pneumonia, hepatitis, and syphilis were significantly linked with HIV infection. In order to assess the individual effects of the significant variables in each one of the four models, a logistic regression analysis was performed simultaneously controlling for all of the variables. After adjustment for the Bonferroni correction, age group 25-34 years, injection as the only route of using drugs, number of years of injection, and syphilis were the only significant variables remaining.