PubMed Health⌕ Search

Biomedical subjects

T R O'Brien

Publications and source records attributed to T R O'Brien.

At least 37 records · Page 2Linked to original sources
PubMed1998

Genetic acceleration of AIDS progression by a promoter variant of CCR5.

The CCR5 gene encodes a cell surface chemokine receptor molecule that serves as the principal coreceptor, with CD4, for macrophage-tropic (R5) strains of human immunodeficiency virus-type 1 (HIV-1). Genetic association analysis of five cohorts of people with acquired immunodeficiency syndrome (AIDS) revealed that infected individuals homozygous for a multisite haplotype of the CCR5 regulatory region containing the promoter allele, CCR5P1, progress to AIDS more rapidly than those with other CCR5 promoter genotypes, particularly in the early years after infection. Composite genetic epidemiologic analyses of genotypes bearing CCR5P1, CCR5-Delta32, CCR2-64I, and SDF1-3'A affirmed distinct regulatory influences for each gene on AIDS progression. An estimated 10 to 17 percent of patients who develop AIDS within 3.5 years of HIV-1 infection do so because they are homozygous for CCR5P1/P1, and 7 to 13 percent of all people carry this susceptible genotype. The cumulative and interactive influence of these AIDS restriction genes illustrates the multigenic nature of host factors limiting AIDS disease progression.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Effects of age at seroconversion and baseline HIV RNA level on the loss of CD4+ cells among persons with hemophilia. Multicenter Hemophilia Cohort Study.

OBJECTIVE: To assess the impact of age at seroconversion and HIV RNA level in serum during early chronic infection on the initial values and subsequent trends (slopes) of CD4+ lymphocyte counts. DESIGN AND METHODS: In a cohort of 137 HIV-1-positive hemophiliacs with well-estimated dates of seroconversion, baseline HIV RNA level was measured by reverse transcription PCR in serum specimens collected 12-36 months after the estimated date of seroconversion. Baseline values, 24 months after seroconversion, and slopes of CD4+ lymphocyte counts by age and HIV RNA quartile were examined by fitting random effects models that allowed for intrasubject variability. RESULTS: Both age at seroconversion and HIV RNA level were associated with the CD4+ lymphocyte count at baseline and its subsequent slope. The baseline median CD4+ lymphocyte count was 620 x 10(6)/l. Within each HIV RNA quartile, the median CD4+ cell count of the oldest subjects (age 30-58 years) was about 200 x 10(6)/l lower and at least 350 x 10(6)/l lower than the median counts of the younger (age 11-29 years) and youngest (age 2-10 years) subjects, respectively. Within each age-group, the median CD4+ cell count differed by about 200 x 10(6)/l between subjects in the lowest compared with the highest HIV RNA quartiles. The mean slope of the CD4+ lymphocyte count after month 24 was linear on the square-root scale, steeper in children, and did not vary significantly by baseline HIV RNA quartile. There was large variation between subjects that was unexplained by differences in age and HIV RNA level. CONCLUSIONS: By 24 months after HIV seroconversion, the oldest subjects and those with the highest HIV RNA levels during early chronic infection had experienced the most severe depletion of CD4+ cells. Subsequent declines in CD4+ cells varied little by early chronic HIV RNA level or age.

Adolescent↗
PubMed1998

New testing strategy to detect early HIV-1 infection for use in incidence estimates and for clinical and prevention purposes.

CONTEXT: Differentiating individuals with early human immunodeficiency virus 1 (HIV-1) infection from those infected for longer periods is difficult but important for estimating HIV incidence and for purposes of clinical care and prevention. OBJECTIVE: To develop and validate a serologic testing algorithm in which HIV-1-positive persons with reactive test results on a sensitive HIV-1 enzyme immunoassay (EIA) but nonreactive results on a less sensitive (LS) EIA are identified as having early infection. DESIGN: Diagnostic test and testing strategy development, validation, and application. Specimens were tested with both a sensitive HIV-1 EIA (3A11 assay) and a less sensitive modification of the same EIA (3A11-LS assay). SETTINGS AND PARTICIPANTS: For assay development: 104 persons seroconverting to HIV-1 comprising 38 plasma donors, 18 patients of a sexually transmitted disease clinic in Trinidad, and 48 participants in the San Francisco Men's Health Study (SFMHS); 268 men without the acquired immunodeficiency syndrome (AIDS) in the SFMHS who had been infected for at least 2.5 years; and 207 persons with clinical AIDS; for testing strategy validation: 488 men in the SFMHS from 1985 through 1990 and 1275449 repeat blood donors at 3 American Red Cross blood centers from 1993 through 1995; and for HIV-1 incidence estimates: 2717910 first-time blood donors. We retrospectively identified persons eligible for a study of early infection. MAIN OUTCOME MEASURE: Ability to identify early HIV infection. RESULTS: Estimated mean time from being 3A11 reactive/3A11-LS nonreactive to being 3A11 reactive/3A11-LS reactive was 129 days (95% confidence interval [CI], 109-149 days) [corrected]. Our testing strategy accurately diagnosed 95% of persons with early infection; however, 0.4% (1/268) of men with established infection and 2% (5/207) of persons with late-stage AIDS were misdiagnosed as having early HIV-1 infection. Average yearly incidence estimates in SFMHS subjects were 1.5% per year vs observed average incidence of 1.4 per 100 person-years. Incidence in repeat blood donors using the sensitive/less sensitive assay testing strategy was 2.95 per 100000 per year (95% CI, 1.14-6.53/100000) vs observed incidence of 2.60 per 100000 person-years (95% CI, 1.49-4.21/100000). Overall incidence in first-time blood donors was 7.18 per 100000 per year (95% CI, 4.51-11.20/100000) and did not change statistically significantly between 1993 and 1996. Use of the sensitive/less sensitive testing strategy alone would have identified all 17 persons with antibodies to HIV-1 eligible for a study of early HIV-1 infection and would have increased enrollment. CONCLUSIONS: The sensitive/less sensitive testing strategy provides accurate diagnosis of early HIV-1 infection, provides accurate estimates of HIV-1 incidence, can facilitate clinical studies of early HIV-1 infection, and provides information on HIV-1 infection duration for care planning.

AIDS Serodiagnosis↗
PubMed1998

Longitudinal HIV-1 RNA levels in a cohort of homosexual men.

HIV-1 RNA levels measured during early chronic infection strongly predict subsequent clinical events. In the short term, HIV-1 is in a steady state, but the stability of viral levels over time is incompletely understood. We used reverse transcriptase polymerase chain reaction (RT-PCR) to examine changes in serum HIV-1 RNA levels in 111 HIV-1-infected homosexual men during the period from 1982 to 1992 and their relation to clinical outcomes. HIV-1 RNA levels increased by a median of 0.08 log10 copies/ml/year (p=.0001). HIV-1 RNA levels rose either gradually or abruptly for the majority of subjects; 41% had no increase. Among subjects surviving at least 8 years, HIV-1 RNA was stable during the first 4 years after seroconversion (median. 0.00 log10 copies/ml/year), but rose in years five through eight (median, 0.06 log10 copies/ml/year; p=.04). The annual HIV-I RNA level was more predictive of AIDS (relative hazard [RH], 1.75 per 0.5 log difference; 95% confidence interval [CI], 1.38-2.21; likelihood ratio [LR], 26.2) than the initial level alone (RH, 1.39; 95% CI. 1.10-1.76; LR, 8.5). We conclude that most HIV-1-infected persons lack a long-term viral setpoint and that failure to account for evolution of the viral level can lead to underestimation of the risk of progression.

Adult↗
PubMed1998

Genetic restriction of AIDS pathogenesis by an SDF-1 chemokine gene variant. ALIVE Study, Hemophilia Growth and Development Study (HGDS), Multicenter AIDS Cohort Study (MACS), Multicenter Hemophilia Cohort Study (MHCS), San Francisco City Cohort (SFCC)

Stromal-derived factor (SDF-1) is the principal ligand for CXCR4, a coreceptor with CD4 for T lymphocyte cell line-tropic human immunodeficiency virus-type 1 (HIV-1). A common polymorphism, SDF1-3'A, was identified in an evolutionarily conserved segment of the 3' untranslated region of the SDF-1 structural gene transcript. In the homozygous state, SDF1-3'A/3'A delays the onset of acquired immunodeficiency syndrome (AIDS), according to a genetic association analysis of 2857 patients enrolled in five AIDS cohort studies. The recessive protective effect of SDF1-3'A was increasingly pronounced in individuals infected with HIV-1 for longer periods, was twice as strong as the dominant genetic restriction of AIDS conferred by CCR5 and CCR2 chemokine receptor variants in these populations, and was complementary with these mutations in delaying the onset of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Reproductive behavior in HIV-discordant heterosexual couples: implications for counseling.

The development of effective behavioral interventions is critical to controlling the HIV epidemic. Although heterosexual transmission accounts for a growing proportion of new infections in the United States, little is known about factors that influence sexual behavior in HIV-discordant heterosexual couples. The objective of this study was to examine the reproductive behaviors of HIV-discordant heterosexual couples. Data were obtained on 71 discordant couples enrolled in a study of HIV heterosexual transmission. Results showed that women in such couples have pregnancy rates similar to those of women of reproductive age in the general population. One seroconversion occurred as a result of pregnancy attempt. These results suggest the need for educational efforts directed at HIV-discordant heterosexual couples.

Adult↗
PubMed1998

Effect of hoof trimming on the occurrence of distal phalangeal palmar process fractures in foals.

This study sought to determine if extensive trimming of the front hooves of foals results in a higher incidence of palmar process fractures compared to untrimmed foals, and to characterise the clinical course of foals with palmar process fractures with physical findings, hoof measurements and radiography. Twenty foals age 4-8 weeks of multiple breeds were examined every 2 weeks over a 12 week period. Ten foals had both front hooves extensively trimmed every 4 weeks, while 10 foals remained untrimmed. Palmar process fractures occurred in 4 trimmed and 3 untrimmed foals. Four foals with fractures had brief lameness (Grades I-II/V) and hoof tester sensitivity was found inconsistently with fractures. All foals with fractures were sound at the end of the study. Fractures healed based on radiographic evaluations in an average of 8.4 weeks. Two of 3 foals with fractures developed club-footed conformation. None of the measured hoof parameters significantly differed between foals with and without fractures. We conclude that extensive trimming of the heels did not appear to affect the occurrence of palmar process fractures in this group of foals.

Animals↗
PubMed1998

Exclusive and persistent use of the entry coreceptor CXCR4 by human immunodeficiency virus type 1 from a subject homozygous for CCR5 delta32.

Individuals who are homozygous for the 32-bp deletion in the gene coding for the chemokine receptor and major human immunodeficiency virus type 1 (HIV-1) coreceptor CCR5 (CCR5 -/-) lack functional cell surface CCR5 molecules and are relatively resistant to HIV-1 infection. HIV-1 infection in CCR5 -/- individuals, although rare, has been increasingly documented. We now report that the viral quasispecies from one such individual throughout disease is homogenous, T cell line tropic, and phenotypically syncytium inducing (SI); exclusively uses CXCR4; and replicates well in CCR5 -/- primary T cells. The recently discovered coreceptors BOB and Bonzo are not used. Although early and persistent SI variants have been described in longitudinal studies, this is the first demonstration of exclusive and persistent CXCR4 usage. With the caveat that the earliest viruses available from this subject were from approximately 4 years following primary infection, these data suggest that HIV-1 infection can be mediated and persistently maintained by viruses which exclusively utilize CXCR4. The lack of evolution toward the available minor coreceptors in this subject underscores the dominant biological roles of the major coreceptors CCR5 and CXCR4. This and two similar subjects (R. Biti, R. Ffrench, J. Young, B. Bennetts, G. Stewart, and T. Liang, Nat. Med. 3:252-253, 1997; I. Theodoreu, L. Meyer, M. Magierowska, C. Katlama, and C. Rouzioux, Lancet 349:1219-1220, 1997) showed relatively rapid CD4+ T-cell declines despite average or low initial viral RNA load. Since viruses which use CXCR4 exclusively cannot infect macrophages, these data have implications for the relative infection of the T-cell compartment versus the macrophage compartment in vivo and for the development of CCR5-based therapeutics.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Contrasting genetic influence of CCR2 and CCR5 variants on HIV-1 infection and disease progression. Hemophilia Growth and Development Study (HGDS), Multicenter AIDS Cohort Study (MACS), Multicenter Hemophilia Cohort Study (MHCS), San Francisco City Cohort (SFCC), ALIVE Study.

The critical role of chemokine receptors (CCR5 and CXCR4) in human immunodeficiency virus-type 1 (HIV-1) infection and pathogenesis prompted a search for polymorphisms in other chemokine receptor genes that mediate HIV-1 disease progression. A mutation (CCR2-64I) within the first transmembrane region of the CCR2 chemokine and HIV-1 receptor gene is described that occurred at an allele frequency of 10 to 15 percent among Caucasians and African Americans. Genetic association analysis of five acquired immunodeficiency syndrome (AIDS) cohorts (3003 patients) revealed that although CCR2-64I exerts no influence on the incidence of HIV-1 infection, HIV-1-infected individuals carrying the CCR2-64I allele progressed to AIDS 2 to 4 years later than individuals homozygous for the common allele. Because CCR2-64I occurs invariably on a CCR5-+-bearing chromosomal haplotype, the independent effects of CCR5-Delta32 (which also delays AIDS onset) and CCR2-64I were determined. An estimated 38 to 45 percent of AIDS patients whose disease progresses rapidly (less than 3 years until onset of AIDS symptoms after HIV-1 exposure) can be attributed to their CCR2-+/+ or CCR5-+/+ genotype, whereas the survival of 28 to 29 percent of long-term survivors, who avoid AIDS for 16 years or more, can be explained by a mutant genotype for CCR2 or CCR5.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Detection of serum antibodies to a Kaposi's sarcoma-associated herpesvirus-specific peptide.

Kaposi's sarcoma (KS)-associated herpesvirus/human herpesvirus type 8 (KSHV/HHV-8) may play an etiologic role in the pathogenesis of KS. In an attempt to assess KSHV/HHV-8 infection, an ELISA was developed using an 18-amino acid peptide from a putative minor capsid protein of KSHV/HHV-8 conjugated to bovine serum albumin. Overall, sera from human immunodeficiency virus type 1 (HIV-1)-positive patients with KS had a higher reactivity in the assay than did sera from HIV-1-positive patients without KS (P = .018). Of 35 HIV-1-positive patients with KS, 60% were antibody positive, compared with 27% of 33 HIV-1-positive patients without KS. Of 30 healthy blood donors, 20% were antibody positive. The ELISA responses did not correlate with antibody titers to Epstein-Barr virus. Given the homology and antigenic relatedness between KSHV/HHV-8 and Epstein-Barr virus, serologic assays involving unique KSHV/HHV-8 peptides may prove to be valuable in defining the epidemiology and clinical expression of this virus.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Serum HIV-1 RNA levels and time to development of AIDS in the Multicenter Hemophilia Cohort Study.

OBJECTIVE: To determine if the long-term incidence of the acquired immunodeficiency syndrome (AIDS) is related to human immunodeficiency virus type 1 (HIV-1) RNA levels measured early in HIV-1 infection. DESIGN: Epidemiologic cohort study. SETTING: Five hemophilia treatment centers in the United States. SUBJECTS: A total of 165 subjects with hemophilia and HIV-1 infection (age at HIV-1 seroconversion, 1-66 years) followed from 1979 to 1995. METHODS: The HIV-1 RNA level was measured by polymerase chain reaction over a range of 200 to 1 million or more HIV-1 RNA copies/mL in archived serum specimens collected 12 to 36 months (median, 27 months) after the estimated date of HIV-1 seroconversion. Kaplan-Meier methods were used to examine the risk of AIDS and proportional hazards models were used to estimate relative hazards. RESULTS: The HIV-1 RNA values were similar in subjects younger than 17 years at seroconversion (median, 5214 copies/mL) and those 18 to 34 years old (median, 4693 copies/mL), but higher in those 35 years or older (median, 12069 copies/mL) (P = .02 compared with each younger group). At 10 years after seroconversion, the proportions of subjects with AIDS were 72% among subjects with 100,000 or more HIV-1 RNA copies/mL measured 12 to 36 months after HIV-1 seroconversion (n = 9), 52% among subjects with 10,000 to 99,999 copies/mL (n = 55), 22% among subjects with 1000 to 9,999 copies/mL (n = 82), and 0% among subjects with fewer than 1000 copies/mL (n = 19) (P < .001). The age-adjusted relative hazard for AIDS for subjects with 10,000 or more copies/mL was 14.3 (95% confidence interval, 1.9-105.6) compared with subjects with fewer than 1000 copies/mL. CONCLUSIONS: The HIV-1 RNA level during early chronic HIV-1 infection is a strong, age-independent predictor of clinical outcome; low levels define persons with a high probability of long-term AIDS-free survival.

Acquired Immunodeficiency Syndrome↗