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Biomedical subjects

D Vlahov

Publications and source records attributed to D Vlahov.

At least 163 records · Page 9Linked to original sources
PubMed1997

Comparison of a tuberculin interferon-gamma assay with the tuberculin skin test in high-risk adults: effect of human immunodeficiency virus infection.

A novel, whole blood interferon-gamma (IFN-gamma) assay was evaluated to determine its suitability for detecting Mycobacterium tuberculosis exposure in intravenous drug users with or without human immunodeficiency virus (HIV) infection. Whole heparinized blood was incubated overnight in separate wells with tuberculin purified protein derivative (PPD), saline, and mitogen controls. Levels of IFN-gamma in plasma supernatants were determined by rapid ELISA. Participants were then administered the tuberculin skin test (TST) and tested for cutaneous anergy. The whole blood IFN-gamma test agreed (89%-100%) with a positive TST in both HIV-seropositive and -seronegative subjects, but reactivity to PPD was more detectable by the whole blood assay among those with negative TSTs or anergy. TST induration diameter and IFN-gamma responses were correlated (Spearman's p = .45, P = .0001), but both responses were blunted by HIV infection. In summary, tuberculin reactivity appears to be more detectable by the whole blood IFN-gamma assay than by TST, and the assay requires no return visit for test reading.

Adult↗
PubMed1997

Persistence and clinical significance of hepatitis G virus infections in injecting drug users.

To assess the persistence of hepatitis G virus (HGV) infection and its association with liver disease, HGV RNA was assessed in the most recent serum sample for 246 long-term injecting drug users (IDUs) and in prior specimens for those found HGV RNA-positive. HGV RNA was detected at the most recent visit in 38 (15.4%). For 31 (82%), HGV RNA was also found at all prior visits occurring a median of 6.1 years earlier. HGV-positive IDUs were younger and had fewer years of drug use, suggesting that HGV RNA had previously been cleared. Serial samples from 29 short-term IDUs were then assessed. HGV RNA was detected in 9 (31%) of 29 short-term IDUs, and 5 (56%) of the 9 HGV infections cleared. No differences were detected in serum levels of liver-related enzymes among HGV RNA-positive and -negative participants (P > .20). HGV infection is not associated with hepatic inflammation. HGV clearance occurs after many acute infections but uncommonly in persons who remain RNA-positive years after exposure.

Adolescent↗
PubMed1997

Syphilis serology in human immunodeficiency virus infection: evidence for false-negative fluorescent treponemal testing.

Injection drug users were assessed serologically for human immunodeficiency virus infection and syphilis every 6 months. Treatment histories were reviewed for any high-titer biologic false-positive (BFP) reactors, that is, persons with rapid plasma reagin (RPR) titers > or = 1:4 and negative results for fluorescent treponemal antibody absorption (FTA-ABS) tests. Selected sera were analyzed further by immunoblotting for the presence of antibodies reactive with specific Treponema pallidum antigens. Of 112 BFP reactors, 35 (31%) had at least one RPR test reactive at a dilution >1:8 while the FTA-ABS test remained nonreactive. Five reactors (4.5%) converted from nonreactive to reactive by FTA-ABS test; 4 (3.6%) were reactive by FTA-ABS tests but later became nonreactive. Antibodies to T. pallidum membrane antigens were detected in some samples that were persistently nonreactive by FTA-ABS test. Serologic patterns over time, along with very high-titer BFP reactions and reactivity with T. pallidum-specific antigens, suggest that some BFP reactions may represent FTA-negative syphilis.

Antibodies, Bacterial↗
PubMed1997

The influence of drug use patterns on the rate of CD4+ lymphocyte decline among HIV-1-infected injecting drug users.

OBJECTIVES: To assess the relationship between various injecting drug use patterns and the rate of CD4+ lymphocyte decline in HIV-1-infected injecting drug users in Baltimore, Maryland, USA. METHODS: A cohort of 605 HIV-1-infected injecting drug users was recruited between 1988 and early 1989 in East Baltimore using extensive community outreach techniques. The participants were interviewed semi-annually to collect information on drug use practices. The outcome measure of interest was the rate of CD4+ lymphocyte decline between pairs of CD4+ lymphocyte counts. A mixed model was used to evaluate the relationship between the change in CD4+ lymphocyte count per month and previous CD4+ lymphocyte count and various drug use variables. RESULTS: The 605 HIV-infected injecting drug users had a median initial CD4+ lymphocyte count of 513 cells x 10(6)/l. Using 3209 paired observations, the mean change in CD4+ lymphocyte count was -3.2 cells x 10(6)/l per month. The rate of decline was higher in those with a higher level of CD4+ lymphocytes (P < 0.01) and length of drug use (P < 0.01), but did not vary by injection frequency or injection intensity of specific drug types. Although animal studies have suggested that the pattern of drug administration (continuous versus intermittent) and episodes of withdrawal or overdose might impact the rate of CD4+ lymphocyte decline, this was not observed in the present study. CONCLUSION: Patterns of injecting drug use, based on self-report, were not associated with the rate of decline in CD4+ lymphocytes.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Vitamin A levels and human immunodeficiency virus load in injection drug users.

Although low plasma vitamin A levels are associated with increased mortality and higher vertical transmission during human immunodeficiency virus (HIV) infection, it is unknown whether plasma low vitamin A levels are a marker for circulating HIV load. We conducted a cross-sectional study within a prospective cohort study of injection drug users in order to evaluate the relationship between plasma vitamin A levels and HIV viral load. Plasma vitamin A level was measured by high-performance liquid chromatography. Infectious viral load was measured by quantitative microculture of serial fivefold dilutions of 10(6) peripheral blood mononuclear cells. A total of 284 HIV-infected adults (79 women, 205 men) were studied. Plasma vitamin A levels consistent with deficiency were found in 28.9% of adults. A total of 38.0% of women and 25.3% of men had vitamin A deficiency (P < 0.04). The median infectious viral load for the entire study population was 8 infectious units per million cells. No significant relationship between plasma vitamin A levels and infectious viral load was observed in these injection drug users. This study suggests that there is no correlation between HIV viral load and plasma vitamin A levels in injection drug users, and these variables may represent independent risk factors during HIV infection. HIV-infected adult women appear to be at higher risk of developing vitamin A deficiency.

Adult↗
PubMed1997

Incidence and risk factors for hepatitis C among injection drug users in Baltimore, Maryland.

Between 1988 and 1996, the incidence of and risk factors for hepatitis C virus (HCV) infection were studied in a cohort of injection drug users in Baltimore, Maryland. By second-generation antibody testing of stored serum samples, 142 participants were found to be susceptible to HCV at the time they entered the study. After a median follow-up of 6.5 years, 43 participants (30.3%) developed antibodies to HCV (anti-HCV). The overall incidence was 6.4 cases per 100 person-years, but a substantial decline in the annual incidence rate was observed after the first 2 years (1988 to 1990, 13.4/100 person-years; 1991 to 1996, 2.3/100 person-years [P = 0.0001 for trend]). Participants who acknowledged active drug use, especially those who acknowledged frequent use and sharing of drug paraphernalia, were at increased risk of HCV infection. However, high-risk sexual practices were not associated with HCV seroconversion. Efforts to reduce HCV infection must be focused on curbing drug use and especially on the sharing of needles and drug paraphernalia.

Adult↗
PubMed1997

Comparison of PCR and hybrid capture methods for detection of human papillomavirus in injection drug-using women at high risk of human immunodeficiency virus infection.

We compared Hybrid Capture, a new technique for detection of human papillomaviruses (HPV), with a PCR assay based on L1 consensus primers. By both methods, the HPV prevalence was higher in human immunodeficiency virus (HIV)-positive women than in HIV-negative women. PCR had a higher sensitivity (0.89 versus 0.48) but lower specificity (0.43 versus 0.93) for detection of Pap smear abnormalities, compared to Hybrid Capture. The higher intensity of hybridization signal by PCR was related to higher estimates of viral load by Hybrid Capture.

DNA, Viral↗
PubMed1997

Seroreactivity to hepatitis E virus in areas where the disease is not endemic.

If the occurrence of hepatitis E virus antibody (anti-HEV) in regions where the disease is not endemic represents infection, rates may be greater in high-risk populations and behavioral correlates may reflect recognized transmission modes. Serum samples from 300 homosexual males, 300 injection drug users (IDUs), and 300 blood donors from Baltimore, Md., were tested for anti-HEV by enzyme immunoassay. Anti-HEV was found in an unexpectedly high percentage of homosexual men (15.9%) and IDUs (23.0%). However, anti-HEV was present in a similar proportion of blood donors (21.3%) (P > 0.05), while hepatitis A, B, and C virus antibodies were more prevalent in the high-risk groups (P < 0.001). Among homosexual men, anti-HEV was not significantly correlated with a history of hepatitis, high-risk sexual practices, or sexually transmitted infections, in contrast to hepatitis A and B antibodies. Among IDUs, anti-HEV was not significantly associated with a history of hepatitis or high-risk drug-using practices, as was found with hepatitis C antibodies. In a setting without endemic hepatitis E disease, there was no evidence that anti-HEV reflected subclinical infection. Until the basis for HEV seroreactivity in such areas is elucidated, anti-HEV results should be interpreted with caution.

Hepatitis E↗
PubMed1997

Comparison of neuropsychological performance between AIDS-free injecting drug users and homosexual men.

We performed a cross-sectional comparison of the baseline neuropsychologic performance of 107 injecting drug users and 230 homosexual men participating in two longitudinal studies. Cognitive tests measured attention, memory and psychomotor speed. Using multiple regression modelling, the analysis adjusted for age, IQ score, race, six-month history of alcohol, cocaine, opiates and marijuana use, HIV serostatus and CD4+ lymphocyte count. Injecting drug users showed significantly poorer scores in all neuropsychologic tests in the univariate analysis. However, once adjusted for age, IQ score and race, only Rey Complex Figure tests were significantly worse among injecting drug users. These data indicate that age and IQ score rather than risk group account primarily for the differences in the cognitive performance, regardless of serostatus and CD4+ count.

Adult↗
PubMed1997

HIV infection and cognition in intravenous drug users: long-term follow-up.

A cohort of 185 HIV-infected injection drug users (IDUs) and seronegative controls was followed with semiannual neuropsychological assessments for up to 4.5 years. Changes in cognitive performance over time were evaluated, and results of seronegative controls were used to adjust for level of education and practice effects. The effects of duration of follow-up, decline in CD4+ count, development of clinical symptoms, antiretroviral use, and diagnosis of AIDS on changes in neuropsychological performance over time were assessed with regression models using the generalized estimating equation approach. Improvement in performance over time, consistent with practice effects, was observed for all measures. The only subtest for which the magnitude of the practice effects was mildly attenuated relative to the seronegative controls was Grooved Pegboard, dominant hand. After adjusting for disease progression and antiretroviral therapy use, none of the time trends for the neuropsychological test scores were significant, suggesting no decline in performance of the seropositive patients relative to the seronegative controls. With development of clinical symptoms, there was a trend in the direction of declining performance. For subjects reporting two or more symptoms but not using antiretroviral therapy, the trend was not significant, whereas having two or more symptoms and using antiretroviral therapy was associated with significantly worse performance on tests of psychomotor speed and memory. With development of AIDS, a significant decline in performance was observed on measures of motor and psychomotor speed as well as memory. There is thus no evidence to suggest that HIV infection in the context of chronic drug and alcohol use significantly alters the frequency or rate of progression of cognitive symptoms. These findings suggest that the natural history of cognitive changes secondary to HIV infection is similar among HIV-infected IDUs and other risk groups such as homosexual/bisexual men.

Adult↗
PubMed1997

Syphilis in injecting drug users: clues for high-risk sexual behaviour in female IDUs.

The objective was to measure the gender-specific differences for syphilis and for the sexual transmission of human immunodeficiency virus (HIV) in a cross-sectional analysis of injecting drug users (IDUs) admitted to detoxification between February 1987 and January 1990. HIV was determined by enzyme-linked immunosorbent assay (ELISA) and confirmed with Western blot. For syphilis reactive samples to a rapid plasma reagent (RPR) were confirmed with treponemal tests (FTA-ABS or MHA-TP). Of the 386 heterosexual IDUs, 68% were HIV-positive and 4.7% had serologic syphilis (RPR and FTA-ABS or MHA-TP positive). Syphilis was higher in women (12%) than in men (3%), and women reported a significantly (P < 0.001) higher number of sex partners. Men had an IDU as a sex partner more often than women did (P = 0.001). Serologic syphilis in women was associated with having had more than one sexual partner in the previous year (P = 0.028) but this association was not present in men. HIV infection was not associated with syphilis in male IDUs. However, HIV was present in all women with syphilis that reported more than one partner.

Adolescent↗
PubMed1997

Markers of response to zidovudine monotherapy among treated HIV seroconverters. Italian Seroconversion Study.

The aim of the study was to evaluate indicators of response to zidovudine monotherapy in terms of progression to AIDS and death in a cohort of human immunodeficiency virus (HIV) seroconverters. From a larger observational epidemiological cohort of 1,024 HIV seroconverters we identified 315 persons on zidovudine monotherapy. In this treated cohort, age, sex, risk group, constitutional symptoms, CD4 cell count, and p24 antigen levels at initiation of treatment and 6 months later were examined separately for two outcomes, AIDS and death, using standard survival methods. The variables measured at the visit at which zidovudine monotherapy was initiated that predicted more rapid progression to AIDS were CD4 cell count (RH = 2.61); constitutional symptoms (RH = 2.56); p24 antigenaemia level (RH = 2. 17); and subsequent change in CD4 cell count (> 30% decline) contributed additional predictive information (RH = 2.70). Results were similar for mortality, and did not vary significantly by risk group. In a tested subset of patients, p24 antigenaemia was associated with high levels of plasma RNA viral load. The median number of HIV RNA copies was about 28,000 copies/ml among p24 antigen-positive individuals and about 7,700 copies/ml among participants who were persistently negative for p24 antigenaemia. CD4 cell count, symptoms and p24 antigenaemia at the start of therapy and CD4 cell decline after initiation of treatment are early indicators of disease progression in zidovudine-treated patients. The combined use of these indicators may help to better predict who will respond to zidovudine or to other antiretroviral therapies.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Helper T-lymphocyte count. TRAx CD4 test kit versus conventional flow cytometry.

BACKGROUND: We evaluated a newly developed enzyme-linked immunosorbent assay system for measuring helper T-lymphocyte count. METHODS: Data from 111 human immunodeficiency virus-infected injection drug users in a cohort study were analyzed by flow cytometry and independent duplicate runs of the TRAx enzyme-linked immunosorbent assay. RESULTS: The mean helper T-cell counts were 470, 480, and 506 per microliter by flow cytometry and TRAx runs 1 and 2, respectively. The correlation coefficients for TRAx runs 1 and 2 with the flow cytometry results as the dependent variable were .93 and .91, respectively. A cross-tabulation of the enzyme-linked immunosorbent assay helper T-lymphocyte counts with flow cytometry counts showed agreement of 71% and 76% when the flow count was between 201 and 500, and 88% and 90% when it was greater than 500 cells per microliter. In those samples with 200 or fewer helper T cells, agreement was 73% and 41% for each TRAx run. CONCLUSIONS: The TRAx enzyme-linked immunosorbent assay system is an acceptable method for measuring helper T-lymphocyte count, but should be recalibrated for better performance at helper T-cell counts below 200 per microliter.

CD4 Lymphocyte Count↗
PubMed1996

Antibodies to Bartonella species in inner-city intravenous drug users in Baltimore, Md.

BACKGROUND: Bartonella quintana has recently been associated with homeless alcoholic men. Both B quintana and Bartonella henselae have been shown to be opportunistic pathogens of people with acquired immunodeficiency syndrome. The reservoirs and modes of transmission of these infections are incompletely known. OBJECTIVES: To examine serum samples that were taken from inner-city intravenous (IV) drug users for antibodies to Bartonella organisms to determine whether there is an urban transmission cycle for Bartonella species and to examine the demographic and behavioral characteristics of IV drug users to identify possible risk factors for infection with any of these agents. MATERIALS AND METHODS: A serologic survey was conducted, using a convenience sample of serum specimens collected during a study of IV drug use and human immunodeficiency virus infection among 630 inner-city residents in Baltimore, Md. A detailed questionnaire was administered at the initial collection of serum, and additional serum collections and questionnaire updates were made at 6-month intervals. The most recent available serum sample was tested for Bartonella antibody titer by using the indirect immunofluorescent antibody test with 3 antigens: Bartonella elizabethae, B henselae, and B quintana. Univariate and multivariate analyses of selected potential demographic and behavioral risk factors were conducted. RESULTS: Antibodies to Bartonella were highly prevalent in this group; more than 37% of all samples reacted with at least 1 antigen. Overall seroprevalence of antibodies to B elizabethae, B henselae, and B quintana was 33%, 11%, and 10%, respectively. Current IV drug use, frequency of injection, and seronegative human immunodeficiency virus status were significantly associated with Bartonella antibody presence, but these associations varied by analysis. There was a significant inverse association of antibody prevalence to B henselae and B quintana by using CD4+ cell counts among human immunodeficiency virus-seropositive individuals. CONCLUSIONS: Intravenous drug users have an elevated prevalence of antibodies to Bartonella organisms and may be at significant risk of becoming infected. Current IV drug use, high frequency of injection, and seronegative human immunodeficiency virus status are significant risk factors for an increased prevalence of Bartonella antibodies. The current natural histories of Bartonella species are rapidly changing, and mechanisms of transmission remain unknown.

Adult↗
PubMed1996

HIV testing behaviors in a population of inner-city women at high risk for HIV infection.

The relationship between HIV testing history. HIV serostatus, and risk behaviors was examined to investigate factors associated with obtaining an HIV test, returning for results, or receiving multiple tests. Seven hundred and five volunteers for an HIV study were questioned about prior HIV testing, drug and sexual practices, and sociodemographic characteristics. Women who reported a prior HIV test were compared with those without a previous test, women who returned for test results were compared with those not returning; and women who reported multiple tests were compared with those having only one test. Seventy-five percent of the women reported a prior test; 12% had not returned for test results; 46% reported multiple tests. Women reporting higher levels of HIV risk behaviors were more likely to have been tested and to return for results. Injection drug use and having four or more sex partners were significantly associated with repeated HIV testing. Over one third of the women with substantial HIV risk practices had not been HIV tested or failed to obtain test results. Women who obtained multiple HIV tests were more likely to report high-risk practices in spite of having received risk counseling with repeated testing.

AIDS Serodiagnosis↗
PubMed1996

People and places: behavioral settings and personal network characteristics as correlates of needle sharing.

Sharing of contaminated needles constitutes one of the primary modes of HIV transmission in the U.S. This study examined social and environmental factors as possible correlates of needle sharing in a sample of inner-city drug users in Baltimore, Maryland. Drug users' social context was assessed through an analysis of personal networks, and the environmental context of drug use was assessed through a delineation of injection settings. The 330 respondents participating in an HIV prevention study were administered two surveys an average of 5.2 months apart. An examination of the association of network characteristics at baseline and needle sharing at followup revealed that the factors of higher total network density, larger drug network size, and injecting at friends' residences were positively associated with reports of sharing needles that had been cleaned with bleach. Sharing of needles that had not been disinfected with bleach was positively associated with reports of injecting in semipublic areas (streets, rooftops, parks, cars, public bathrooms, and abandoned buildings). These data support ecological and resource models of needle sharing and suggest the potential utility of network-oriented strategies for reducing needle sharing among injecting drug users.

Adult↗
PubMed1996

Genetic restriction of HIV-1 infection and progression to AIDS by a deletion allele of the CKR5 structural gene. Hemophilia Growth and Development Study, Multicenter AIDS Cohort Study, Multicenter Hemophilia Cohort Study, San Francisco City Cohort, ALIVE Study.

The chemokine receptor 5 (CKR5) protein serves as a secondary receptor on CD4(+) T lymphocytes for certain strains of human immunodeficiency virus-type 1 (HIV-1). The CKR5 structural gene was mapped to human chromosome 3p21, and a 32-base pair deletion allele (CKR5Delta32) was identified that is present at a frequency of approximately0.10 in the Caucasian population of the United States. An examination of 1955 patients included among six well-characterized acquired immunodeficiency syndrome (AIDS) cohort studies revealed that 17 deletion homozygotes occurred exclusively among 612 exposed HIV-1 antibody-negative individuals (2.8 percent) and not at all in 1343 HIV-1-infected individuals. The frequency of CKR5 deletion heterozygotes was significantly elevated in groups of individuals that had survived HIV-1 infection for more than 10 years, and, in some risk groups, twice as frequent as their occurrence in rapid progressors to AIDS. Survival analysis clearly shows that disease progression is slower in CKR5 deletion heterozygotes than in individuals homozygous for the normal CKR5 gene. The CKR5Delta32 deletion may act as a recessive restriction gene against HIV-1 infection and may exert a dominant phenotype of delaying progression to AIDS among infected individuals.

Acquired Immunodeficiency Syndrome↗