Biomedical subjects

S Chen

Publications and source records attributed to S Chen.

At least 973 records · Page 54Linked to original sources

PubMed1996

Spontaneous melanocytosis in transgenic mice.

Clone B is a 2-kb fragment of cloned genomic DNA involved in adipocyte differentiation in vitro. Insertion of this DNA fragment into the genome of a variety of cell lines results in committing the recipient cells to undergo adipocyte differentiation. Construction of transgenic mice with Clone B DNA resulted in an unexpected phenotype--spontaneous melanocytosis. The present study describes the distribution and morphology of melanin-containing lesions in these transgenic mice. Spontaneous melanin-containing dermal lesions appeared on the ears, snout, and perianal regions of transgenic mice by the age of 3-4 months. Multifocal dermal masses rapidly developed into raised lesions, which appeared to spread to adjacent skin. Ultrastructural examination of lymph nodes, spleen, and dermal lesions of these mice revealed membrane-bound melanin with effacement f the organelle structure of severely affected cells. Protein gel electrophoresis revealed elevated activity of tyrosinase in the pinnae, skin, perianal mass, and lymph nodes. This line of transgenic mice may provide a useful model for investigation of the etiology and progression of benign and malignant melanin-containing tumors.

Animals↗

PubMed1996

The Medical Student Expectation Scale (MSES): a device for measuring students' expectations of each others' values and behaviours.

A study assessing the differences between institutional and matriculants' expectations of students' attitudes and behaviour was undertaken in 1992 at the Drew/UCLA Medical Education Program (DUMEP) in Los Angeles, California. Responding to a 33-item questionnaire utilizing 5-point Likert scales were 113/122 students in the classes of 1992 through to 1996. Factor analysis yielded two factors accounting for 61% of the total variance. Two subscales (Personal Trait Subscale and Drew Mission Subscale) containing a total of nine items comprise the Medical Student Expectation Scale (MSES). The alphas and standardized item alphas of these two subscales were 0.7531 and 0.8287 (Personal Trait Subscale) and 0.7304 and 0.7406 (Drew Mission Subscale), indicating good reliability. Correlation coefficients for continuous variables were calculated in order to determine subgroup responses to the subscales and their component items. While the students' overall responses indicated commitment to the values of the Charles R Drew University of Medicine and Science, subgroup responses varied. The strongest supporters of the University's values were older students, blacks, and those having better undergraduate performance in non-science areas. Least likely to agree with University values were students having better performances in the sciences (grade-point average and MCAT scores) and those of Mexican-American ethnicity. The scores of participating classes documented a secular trend away from endorsement of the values of the Drew University. Following further study, the MSES may be useful in student selection and curriculum design.

Attitude of Health Personnel↗

PubMed1996

Classical Kaposi's: a rare cause of gastrointestinal haemorrhage.

Classical Kaposi's sarcoma (KS) is an indolent neoplasm involving mucocutaneous sites predominantly in elderly Mediterranean or Jewish persons. Whilst gastrointestinal involvement is common, it is usually asymptomatic. This case report presents a case of massive gastrointestinal haemorrhage in a patient with stable cutaneous disease and outlines options for the investigation and management of this rare complication.

Aged↗

PubMed1996

Crying patterns in preterm infants.

Healthy infants born at term cry most in the first three months of life, with a peak and increased crying in the evening during the second month. To determine whether the crying of preterm infants manifests similar features, the pattern of crying from 40 weeks gestational age through 24 weeks corrected age was described for 35 relatively healthy preterm infants born between 28 and 34 weeks gestational age. Despite their additional extra-uterine experience, they still cried significantly more after 40 weeks gestational age, with a peak and evening clustering at 6 weeks corrected age. The age of peak crying was not related to gestational age at birth, weight for gestational age, or a variety of perinatal and neurological indices. The results support the argument that the early-peak pattern is a robust maturational feature of early development and may be universal to human infancy.

Age Distribution↗

PubMed1996

Use of the polymeric matrix as internal standard for quantitation of in vivo delivery of tetracycline HCl from Actisite tetracycline fiber during periodontal treatment.

Actisite (tetracycline hydrochloride) periodontal fiber is a 23 cm monofilament containing 12.7 mg tetracycline HCl homogeneously dispersed in a polymer. This product is indicated as an adjunct to scaling and root planing to reduce pocket depth and bleeding on probing in patients with adult periodontitis. The sustained-release system, placed in the periodontal pocket for 10 d, releases the antibiotic through mechanisms of diffusion and osmosis. A study was conducted in 13 patients with moderate to severe adult periodontitis to evaluate the amount of tetracycline HCl released during therapy (based on residual drug content). Fibers placed in the pocket remained in place for an average of 9 d. Each patient had 1-4 teeth treated with fiber therapy. At the termination of therapy samples from 29 teeth were retrieved and analyzed. The amount of matrix polymer was used as an internal standard for the quantitation of tetracycline, eliminating any uncertainties with respect to recovery or contamination. An average of 31% (SD 9%) of the tetracycline HCl content was released from the fiber during the treatment period. No single fiber had less than 50% of the original drug remaining. The study demonstrated that a substantial amount of the tetracycline remains in the Actisite fiber at removal (about 70%), which indicates that substantial drug concentrations are maintained in the pocket for the duration of treatment.

Administration, Topical↗

PubMed1996

Potent CD14-mediated signalling of human leukocytes by Escherichia coli can be mediated by interaction of whole bacteria and host cells without extensive prior release of endotoxin.

How invading microorganisms are detected by the host has not been well defined. We have compared the abilities of Escherichia coli and lipopolysaccharides (LPS) purified from these bacteria to prime isolated neutrophils for phorbol myristate acetate-stimulated arachidonate release, to trigger respiratory burst in 1% blood, and to increase steady-state levels of tumor necrosis factor alpha mRNA in whole blood. In all three assays, bacteria were > or = 10-fold more potent than equivalent amounts of LPS and could trigger maximal cellular responses at ratios as low as one bacterium per 20 to 200 leukocytes. Both E. coli and LPS-triggered responses were enhanced by LPS-binding protein and inhibited by an anti-CD14 monoclonal antibody and the bactericidal/permeability-increasing protein (BPI). However, whereas O polysaccharide did not affect the potency of isolated LPS, intact E. coli carrying long-chain LPS (O111:B4) was less potent than rough E. coli (J5). Furthermore, material collected by filtration or centrifugation of bacteria incubated under conditions used to trigger arachidonate release or chemiluminescence was 5- or 30-fold less active, respectively, than whole bacterial suspensions. Extracellular BPI (not bound to bacteria) inhibited bacterial signalling, but BPI bound to bacteria was much more potent. Taken together, these findings indicate that E. coli cells can strongly signal their presence to human leukocytes not only by shedding LPS into surrounding fluids but also by exposing endotoxin at or near their surface during direct interaction with host cells.

Acute-Phase Proteins↗

PubMed1996

Mutational analysis of the hsp70-interacting protein Hip.

The hsp70-interacting protein Hip participates in the assembly pathway for progesterone receptor complexes. During assembly, Hip appears at early assembly stages in a transient manner that parallels hsp70 interactions. In this study, a cDNA for human Hip was used to develop various mutant Hip forms in the initial mapping of functions to particular Hip structural elements. Hip regions targeted for deletion and/or truncation included the C-terminal region (which has some limited homology with Saccharomyces cerevisiae Sti1 and its vertebrate homolog p60), a glycine-glycine-methionine-proline (GGMP) tandem repeat, and a tetratricopeptide repeat (TPR). Binding of Hip to hsp70's ATPase domain was lost with deletions from the TPR and from an adjoining highly charged region; correspondingly, these Hip mutant forms were not recovered in receptor complexes. Truncation of Hip's Sti1-related C terminus resulted in Hip binding to hsp70 in a manner suggestive of a misfolded peptide substrate; this hsp70 binding was localized to the GGMP tandem repeat. Mutants lacking either the C terminus or the GGMP tandem repeat were still recovered in receptor complexes. Truncations from Hip's N terminus resulted in an apparent loss of Hip homo-oligomerization, but these mutants retained association with hsp70 and were recovered in receptor complexes. This mutational analysis indicates that Hip's TPR is required for binding of Hip with hsp70's ATPase domain. In addition, some data suggest that hsp70's peptide-binding domain may alternately or concomitantly bind to Hip's GGMP repeat in a manner regulated by Sti1-related sequences.

Amino Acid Sequence↗

PubMed1996

Electrophysiological characterization of a motilin agonist, GM611, on rabbit duodenal smooth muscle.

Effects of motilin and a newly synthesized erythromycin derivative, GM611, on membrane potential and currents of rabbit duodenal smooth muscle have been investigated by intracellular potential recording and whole cell patch-clamp technique and compared with results from contractile experiments. Motilin and GM611 (0.01-100 nM) dose dependently produced slowly sustained depolarizations (half-maximal effective dose = 0.15 and 3.9 nM for motilin and GM611, respectively) but exhibited biphasic effects on spike activities superimposed on slow waves. With small depolarizations, the number of spike discharges increased, whereas larger depolarizations markedly reduced spike amplitude. Motilin-induced (or GM611-induced) depolarization appeared to be associated with the activation of monovalent cation-selective channels, and the reduction in the spike amplitude appeared mainly to be associated with inhibition of voltage-dependent Ca2+ channels. Furthermore, data from patch-clamp experiments suggested that Ca2+ release occurred from heparin-sensitive internal stores upon stimulation of motilin receptors by these agonists. Possible implications of these electrophysiological effects in motilin- or GM611-induced tonic and phasic contractions have been discussed.

Animals↗

PubMed1996

Enhanced aggregability of red blood cells of beta-thalassemia major patients.

beta-Thalassemia major (TM), a congenital hemoglobinopathy, is associated with hemodynamic disorders and with structural red blood cell (RBC) anomalies that may indicate impairment of RBC rheological properties. To gain insight into the possible contribution of RBC to the hemodynamic disorders, we studied RBC aggregability, which plays a central role in blood flow, particularly in the microcirculation. RBC aggregate size distribution and morphology of TM RBC were determined using a novel system for image analysis of blood cells in a flow chamber. It was found that the aggregability of RBC of TM patients is markedly enhanced. These cells form large clusters, as opposed to normal rouleaux, and higher shear stress is required to disperse them. The aggregate size of TM RBC is reduced to the normal range after the patients have received a blood transfusion. This study suggests that the hemodynamic disorders observed in TM may be linked to the enhanced RBC aggregability and that improvement of RBC rheological properties may be considered in the treatment of thalassemia.

Adolescent↗

PubMed1996

Parathyroid hormone-related protein inhibits indothelin-1 production.

The effect of human parathyroid hormone-related protein, a powerful vasodilator, on endothelin-1 production in cultured bovine pulmonary arterial endothelial cells was studied. Treatment with parathyroid hormone-related protein(1-34) at concentrations of 10(-9) to 10(-6) mol/L for 24 hours caused dose-dependent suppression of the secretion of endothelin-1, with maximal suppression at 10(-7) mol/L to 74% of the control value. This inhibitory effect was completely abolished by coincubation with 100 ng/mL pertussis toxin, an inhibitor of GTP binding protein. Furthermore, addition of Ng-monomethyl-L-arginine, an inhibitor of nitric oxide synthase, at 10(-3) mol/L significantly blocked the suppressive effect of parathyroid hormone-related protein (1-34) on endothelin-1 secretion, and further addition of 5x10(-3) mol/L L-arginine significantly attenuated the blocking effect of N(G)-monomethyl-L-arginine. Parathyroid hormone-related protein (1-34) at 10(-7) mol/L resulted in an approximately fivefold increase in intracellular cGMP level. Northern blot analysis revealed that parathyroid hormone-related protein (1-34) inhibited both basal and thrombin-induced endothelin-1 gene expression. These findings suggest that the vasodilating property of parathyroid hormone-related protein may be mediated in part through its inhibitory effect on endothelin-1 production, which is probably mediated through nitric oxide and cGMP in endothelial cells. Thus, a feedback regulatory mechanism may exist between parathyroid hormone-related protein and endothelin-1 in the vascular wall.

Animals↗

PubMed1996

Diminished expression of CYP1A1 in urethane-induced lung tumors in strain A/J mice: analysis by in situ hybridization and immunohistochemical methods.

We have investigated the regulation and expression of CYP1A1 in solid and papillary lung tumors induced by the carcinogen urethane. Female strain A/J mice were administered urethane (1 mg/g body wt) intraperitoneally, and when lung tumors were established at 16 weeks, mice were treated with 3-methylcholanthrene to induce CYP1A1. CYP1A1 mRNA was detected by in situ hybridization with a 3H-labeled RNA probe and quantitated by image analysis, whereas CYP1A1 protein was detected by immunohistochemical staining with an avidin-biotin complex procedure. Our results showed that in untreated control and tumor-bearing mice, the CYP1A1 mRNA was present at low levels, but the CYP1A1 protein was not detectable. Treatment with 3-methylcholanthrene induced increased levels of both CYP1A1 mRNA and protein in lung parenchyma and tumor foci. This induction was markedly higher in the parenchyma of control and tumor-bearing lungs than in either solid or papillary tumors. Differences in CYP1A1 mRNA and protein expression were not evident in solid and papillary tumors. In the parenchyma, induced CYP1A1 mRNA and protein were localized in the endothelial and alveolar septal cells. Endothelial cells in tumors also contained substantial CYP1A1 mRNA and protein, whereas low levels of both were found in lung tumor cells. Our finding of significant reduction in inducibility of CYP1A1 protein in conjunction with reduced CYP1A1 mRNA in tumor foci suggests reduced transcriptional activation as a regulatory mechanism. The lack of association between diminished CYP1A1 expression and either the tumor type or the mechanism mediating metabolic activation supports the hypothesis that the persistence of lung tumors may be due, in part, to a restricted capability for the formation of reactive intermediates.

Animals↗

PubMed1996

Immunocytochemical detection of regional protein changes in rat brain sections using computer-assisted image analysis.

We used several approaches to assess the reliability and sensitivity of computer-assisted densitometry to detect regional changes in tissue antigen content as a function of immunohistochemical staining density. We designed a model system to mimic variations in antigen concentration in postfixed, slide-mounted rat brain sections by varying the ratios of conjugated (biotinylated) to unconjugated secondary antibody. Antigen concentration was also varied in tissue discs made from mixing rat brain homogenate with increasing amounts of tissue embedding compound. The monoclonal antibody bd-17 to the beta2/3 subunit of the GABAA receptor was used as the primary antibody. Immunostaining density was visualized with diaminobenzidine (DAB). There was a significant, positive linear relationship (r = 0.97-0.99) between immunostaining intensity and antigen concentration. With this approach, changes in antigen content of less than 10%, as reflected in immunostaining intensity, were detectable in brain sections. The low degree of variability in measures of regional variation in immunostaining in sections from naive rats (n = 7) suggested that the method was suitable for quantitative analysis and indicated the reliability of the method. This systematic study of the utility of computer-assisted image analysis for semiquantitative immunohistochemical analysis found the method to be both reliable and sensitive.

Animals↗

PubMed1996

Lisofylline, an inhibitor of unsaturated phosphatidic acid generation, ameliorates interleukin-1 beta-induced dysfunction in cultured rat islets.

Interleukin-1 beta (IL-1 beta) causes rat islet cell dysfunction through mechanisms that involve inducible nitric oxide synthase (iNOS). However, IL-1 beta also activates several lipid pathways, including those generating phosphatidic acid (PA). Lisofylline (LSF), a water-soluble, nontoxic, selective inhibitor of the PA-1 alpha subspecies, which is stimulated by IL-1 beta and tumor necrosis factor-alpha, has been shown to prevent cytokine-induced cytotoxicity in in vivo animal models. To evaluate the effect of LSF on acute IL-1 beta-induced islet dysfunction, rat islets were exposed to IL-1 beta (0.1 ng/ml) with or without LSF (100 microM) for 24 h, followed by 25 mM glucose (G) stimulation, measurement of rat insulin by RIA, and calculation of the insulin secretion rate. In other experiments, rat islets were precultured for 48 h, then treated for 48 h in 25 mM G with or without IL-1 beta (0.1 ng/ml) and LSF (400 microM), and aliquots of medium were removed at 0, 24, and 48 h for measurement of rat insulin. In addition, islets were exposed to 25 mM G with or without IL-1 beta and LSF, lipids were then extracted, and PA subspecies were identified by TLC and mass spectroscopy, and quantitated using normal phase HPLC. Islets were also exposed to IL-1 beta with or without LSF, and Western immunoblots were performed to evaluate the effect of LSF on iNOS protein expression. IL-1 beta caused a 44% decrease in islet G-stimulated insulin secretion compared to that in untreated islets (P < 0.0005), which was totally reversed by LSF. In addition, IL-1 beta decreased the G-stimulated medium insulin content by 75% at 24 h (P = 0.0004) and 86% at 48 h compared to that in control islets (P < 0.0001). LSF-treated islets maintained 70% of medium insulin content at 24 h (P = 0.11) and 50% at 48 h (P < 0.0001) compared to control islets. HPLC quantitation of PA-1 alpha extracted from islets treated with IL-1 beta alone showed an approximately 15-fold increase over the PA-1 alpha content of islets treated with IL-1 beta and LSF. IL-1 beta-induced expression of iNOS was unchanged with the addition of LSF. These results suggest that LSF is effective in reducing IL-1 beta-induced islet dysfunction, thus supporting the role of lipid mediators such as PA in cytokine-induced islet toxicity.

Adjuvants, Immunologic↗

PubMed1996

Autoantibodies to steroidogenic enzymes in autoimmune polyglandular syndrome, Addison's disease, and premature ovarian failure.

Autoantibodies to steroidogenic enzymes, steroid 17 alpha-hydroxylase (17 alpha-OH), cytochrome P450 side-chain cleavage enzyme (P450scc), and steroid 21-hydroxylase (21-OH), were measured using specific and sensitive immunoprecipitation assays (IPAs) in patients with various forms of autoimmune adrenal disease. Autoantibodies to 17 alpha-OH were detected in 6 of 11 (55%) patients with autoimmune polyglandular syndrome (APS) type I, 8 of 24 (33%) patients with APS type II, 11 of 56 (20%) patients with adrenal cortex antibody (ACA; measured by immunofluorescence)-positive patients without Addison's disease, and only 3 of 64 (5%) patients with Addison's disease. Autoantibodies to P450scc were found at a prevalence similar to those to 17 alpha-OH: in 5 of 11 (45%) APS type I patients, 10 of 24 (42%) APS type II patients, 11 of 56 (20%) ACA-positive patients without Addison's disease, and only 6 of 64 (9%) patients of the Addison disease group. Autoantibodies to 21-OH were found in a majority of patients with APS type I (7 of 11;64%), APS type II (23 of 24; 96%), Addison's disease (41 of 64; 64%), and ACA-positive patients without Addison's disease (48 of 56; 86%). All sera that were positive for 17 alpha-OH or P450scc were also positive for 21-OH autoantibodies, except in 1 case. There was good agreement between the presence of ACA measured by immunofluorescence and 21-OH antibodies measured by IPA in all patient groups studied, and this indicates that 21-OH is a major autoantigen in adrenal autoimmune disease regardless of whether the disease presents as isolated Addison's disease or APS type I or type II. Autoantibodies to 17 alpha-OH and P450scc appeared to be the major components of the steroid-producing cell antibodies measured by immunofluorescence. No autoantibodies to 21-OH, 17 alpha-OH, or P450scc were detected in 17 sera from patients with premature ovarian failure without evidence of adrenal autoimmunity (as judged by immunofluorescence studies), except for 1 serum in which low levels of 17 alpha-OH antibodies were found. Overall, our studies indicate that 35S-labeled 17 alpha-OH, P450scc, and 21-OH can be used successfully in IPAs for their respective autoantibodies. Assays such as these may well be valuable in the immunological assessment of patients at risk for or suspected of adrenal autoimmunity.

Addison Disease↗

PubMed1996

Molecular cloning of human p48, a transient component of progesterone receptor complexes and an Hsp70-binding protein.

A 48-kDa protein (p48) that transiently associates with progesterone receptor during cell-free assembly in rabbit reticulocyte lysate was isolated by two-dimensional gel separation. Tryptic peptide sequences were generated and used to develop an antipeptide antiserum recognizing p48 by Western immunostaining, and this antiserum was used to monitor purification of native p48 from reticulocyte lysate. Eight mouse monoclonal antibodies capable of immunoprecipitating vertebrate p48 were generated. These monoclonal antibodies served as probes to clone ten p48 cDNAs from a HeLa cDNA expression library. One of the cloned cDNAs was sequenced in its entirety and codes for a 369-amino acid protein (calculated Mr = 41,324). Northern blot analysis of RNA from multiple human tissues suggest that p48 may be ubiquitously expressed. Expression of human p48 cDNA in vitro yielded a product that comigrated with rabbit p48 by SDS-PAGE and associated with progesterone receptor in a similar manner. Immunoprecipitation of p48 complexes revealed a common association of p48 with hsp70 and, to a lesser extent, with hsp90 and p60. Thus, it appears that p48 is a novel component of the cytoplasmic molecular chaperone machinery.

Amino Acid Sequence↗

PubMed1996

Interactions of p60, a mediator of progesterone receptor assembly, with heat shock proteins hsp90 and hsp70.

Previous studies on the assembly of progesterone receptor (PR) complexes in vitro have suggested that PR assembly is a dynamic, ordered process involving at least eight nonreceptor proteins. One of these proteins, p60, appears transiently during assembly and is not a component of functionally mature PR complexes. In the present study we observe that a monoclonal antibody specific for p60 can, on the one hand, inhibit formation of mature PR complexes containing heat shock protein 90 (hsp90), p23, and immunophilins and, on the other, enhance recovery of early PR complexes containing hsp70 and Hip (p48). This observation supports a model in which p60 functions at an intermediate stage of PR assembly to facilitate formation of subsequent PR complexes lacking p60. Since p60 is typically found in a complex with hsp90 and hsp70, we have further characterized its interactions with these proteins. P60 can bind either hsp70 or hsp90 independently and in an ATP-independent manner. Since hsp90 and hsp70 do not readily associate on their own, it appears that p60 is the central organizing component of an hsp90-p60-hsp70 complex. Mutational analysis of p60 indicates that the N terminus is required for hsp70 binding, and a central region containing tetratricopeptide repeat motifs is necessary for binding hsp90 and hsp70. The hsp90-p60-hsp70 multichaperone complex is highly dynamic and does not appear to be affected by the hsp90-binding drug geldanamycin. The interactions of hsp70 and hsp90 in intermediate PR complexes are shown to be distinct from their separate interactions in early PR complexes (hsp70) or in mature PR complexes (hsp90). From these results, it appears that p60 is a key mediator in the chaperoned assembly and functional maturation of PR complexes.

Animals↗

PubMed1996

Bradykinin may not be involved in improvement of insulin resistance by angiotensin converting enzyme inhibitor.

We have previously demonstrated that captopril ameliorates glucose intolerance by partially preventing the reduction in postprandial skeletal muscle blood flow. The present study was designed to clarify the mechanism by which ACE inhibitors affect glucose metabolism in fructose (FRU)-fed Wistar rats with hypertension, glucose intolerance and hyperinsulinemia. Eight-week-old male rats (n = 51) were divided into six groups. Controls were given a normal chow, while fructose-rich (55%) chow was administered to the remainder for eight weeks. The different groups were administered alacepril (ALA, 30 mg/kg/day) with or without a continuous infusion of Hoe 140, a kinin B2 receptor antagonist (150 micrograms/kg/day), Hoe 140 alone or TCV-116 (1 mg/kg/day), an angiotensin II receptor antagonist, alone. After measuring the body weight and systolic blood pressure (BP), steady-state plasma glucose (SSPG) levels were determined. FRU significantly increased BP from 141 mmHg in controls to 156 mmHg. ALA with or without Hoe 140 decreased BP to 124 mmHg or 117 mmHg, respectively, but Hoe 140 alone did not affect BP. TCV-116 also decreased BP to 116 mmHg. The SSPG levels increased from 7.58 mM in controls to 8.98 mM in FRU-fed rats. This was lowered with both ALA and TCV-116. Hoe 140 alone, however, did not affect SSPG levels. Hoe 140 did not show any effects on ALA-induced improvement of SSPG. These results suggest that the improvement in glucose tolerance observed with ACE inhibitors is not due to the kinins, and angiotensin II receptor antagonists also improve insulin sensitivity.

Angiotensin Receptor Antagonists↗

PubMed1996

Impoverished women at risk for AIDS. Social support variables.

1. Among impoverished and homeless individuals, little is known about the impact of social support, defined as emotional, informational, and tangible help that may have health-sustaining and stress-reducing functions. 2. A lack of positive social support, unemployment, and the prevalence of poor physical health and psychological distress may contribute to the extreme vulnerability of indigent populations. 3. Information is needed about the social support network of homeless and impoverished women related to personal and behavioral variables, particularly illegal drug use and risky sexual activity, and mental health status.

Acquired Immunodeficiency Syndrome↗