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Biomedical subjects

B R Visscher

Publications and source records attributed to B R Visscher.

At least 37 records · Page 2Linked to original sources
PubMed1994

Resistance to HIV-1 infection. Multicenter AIDS Cohort Study.

Men from the Multicenter AIDS Cohort Study were classified as "susceptible" and "resistant" to HIV infection. Resistant men were still HIV antibody negative in 1993 and were estimated to have had > 45 different anal intercourse partners (median, 92; range, 46-504) in the 2.5 years before visit 2 (1985). Susceptible men were seroconverters who were estimated to have had < 13 different anal partners (median, 4; range, 0-12). Leukocyte groups were compared between the two groups of men. Values were excluded for 12 months before the first antibody-positive visit in the susceptible men. White blood cells, polymorphonuclear neutrophils, total lymphocyte count, CD8+ percentage and number, and CD3+ and CD4+ number were higher in the resistant men. Logistic regression analyses were used to develop 50 bivariate models. Higher levels of neutrophils and CD8+ cells were included in four of the six best-fitting bivariate models, suggesting that each is associated with resistance to HIV-1 infection. These results support the hypothesis that CD8+ cells may modulate the outcome of HIV-1 exposure.

CD8-Positive T-Lymphocytes↗
PubMed1993

Clinical factors associated with weight loss related to infection with human immunodeficiency virus type 1 in the Multicenter AIDS Cohort Study.

The relation between a number of potential risk factors and change in body mass index per semester was examined in a community-based cohort of 1,809 homosexual and bisexual men seropositive for human immunodeficiency virus type 1 (HIV-1). The men were followed semiannually for up to 6.5 years between 1984 and 1990. A total of 9,735 person-semesters of observations were available for analysis. A Markov-type autoregressive model, adjusting for previous body mass index, was used to predict the change in body mass index over each person-semester. Overall, the cohort was gaining weight. An asymptomatic participant 1.8 m in height whose CD4+ cell count was > 750/microliters gained a mean of 0.5 kg each person-semester. In bivariate autoregressive models, diarrhea, fever, oral thrush, acquired immunodeficiency syndrome (AIDS), and CD4+ lymphocyte counts of < 100 and 100-199 cells/microliters were all associated with a significant decrease in body mass index. A significant inverse association was also found between change in body mass index and lymphadenopathy and herpes zoster, but when the intercept coefficient was added, no overall decrease in body mass index was seen in these models. In a final multivariate model, diarrhea was less strongly associated with a change in body mass index (p = 0.057), although AIDS (p = 0.009), fever (p = 0.006), thrush (p = 0.002), and a CD4+ lymphocyte count of < 100 cells/microliters (p < 0.001) all remained independently associated with a decrease in body mass index. Lymphadenopathy and a CD4+ lymphocyte count of 100-199 cells/microliters were also significant covariates in the final model, but neither of the beta coefficients exceeded that of the intercept, indicating that they were not independently associated with a decrease in body mass index. These findings suggest that the importance of diarrhea as a cause of HIV-related weight loss may have been over-estimated in previous clinic-based studies. AIDS and nonspecific markers of progression (fever, thrush, and a CD4+ count of < 100 cells/microliters) were the best predictors of weight loss during a semester.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Relationship of hepatitis B virus infection to human immunodeficiency virus type 1 infection.

The Multicenter AIDS Cohort Study (MACS) was designed to study the natural history of human immunodeficiency virus type 1 (HIV-1) infection, including the relationship between hepatitis B virus (HBV) and HIV-1 infection. In total, 4954 homosexual men were recruited from April 1984 through March 1985 and have been followed up thereafter every 6 months. Hepatitis B surface antigen and hepatitis B core antibody were tested for at the first visit by RIA or EIA; HIV-1 antibody testing was done at each visit by ELISA and confirmed by Western blot assay. The role of HBV infection in HIV-1 seroconversion was studied by stratification for sexual behavior and disease visit by visit. The adjusted risk ratio was 2.02 for hepatitis B surface antigen carriers and 2.14 for hepatitis-immune cases compared with hepatitis B-susceptible subjects. Similar results were obtained using a logistic regression model. After taking into account changes in sexual behavior and disease over time, the authors conclude that past HBV infection remains suspect as a cofactor or as a surrogate for other factors associated with HIV-1 seroconversion.

Blotting, Western↗
PubMed1993

The relationship between T-cell levels and CMV infection in asymptomatic HIV-1 antibody-positive homosexual men.

To investigate the relationship between cytomegalovirus (CMV) infection and progression of HIV-1 disease, a group of 234 asymptomatic, HIV-1 antibody-positive homosexual men were examined for CMV isolation and levels of CMV IgM antibodies, CMV IgG antibodies, and CD4+ and CD8+ T-lymphocytes. CMV IgG antibodies were present in 100% and CMV IgM antibodies in 22% of the men. CMV was isolated from the semen of 45% of the men. No relationship was observed between CMV IgM antibodies and CMV in semen or CD4+ levels. CD4+ cell levels were significantly lower in those from whose semen CMV was isolated. In addition, an inverse relationship was observed between the concentration of CMV in semen and CD4+ levels. We postulate that the seminal tract may be a reservoir for systemic CMV infection in HIV-infected homosexual men. Reinfection from this or other sources may result in recurrent stimulation of HIV-1 replication and lead to a further decline in CD4+ cells. Clarification of whether persistent CMV infection is secondary to HIV-1-induced immunodeficiency or, conversely, promotes a more rapid decline in immunocompetency will require follow-up studies.

AIDS-Related Opportunistic Infections↗
PubMed1992

Asymptomatic HIV infection does not cause EEG abnormalities: results from the Multicenter AIDS Cohort Study (MACS)

We conducted EEG testing in 200 asymptomatic homosexual men, half of whom were HIV seropositive. We chose to include half of the subjects because they were rated as impaired on a neuropsychological screening test. We used both traditional visual EEG interpretation and quantitative EEG analysis. Abnormal EEGs and borderline degrees of EEG slowing occurred in 32% of these men. These EEG changes were not related to HIV serostatus. EEG changes did correlate with the impaired neuropsychological test performance. Clinicians faced with abnormal EEG results or borderline EEG slowing in an asymptomatic HIV-seropositive patient should not attribute the EEG change to effects of the serostatus itself but should look for other causes.

Acquired Immunodeficiency Syndrome↗
PubMed1989

A case-control study of multiple sclerosis.

We conducted a study of 145 persons with multiple sclerosis who had been identified in a 1970 survey and 145 friend controls, to investigate whether the development of MS was associated with exposure to uncommon viruses or an older age at infection with 1 or more common viruses. The most striking finding was a strong positive association for history of infectious mononucleosis (IM), suggesting older age at exposure to Epstein-Barr virus, the most common etiologic agent of IM. We also found significant positive associations for number of different domiciles before adulthood and for visits outside the United States; both would be compatible with an increased likelihood among cases of exposures to uncommon viruses or to multiple strains of a common agent. Cases were younger at menarche, increasing the probability of viral exposure after puberty.

Adolescent↗
PubMed1989

Seroconversion, sexual activity, and condom use among 2915 HIV seronegative men followed for up to 2 years.

A cohort of 2915 HIV-1-seronegative men from the four centers of the Multicenter AIDS Cohort Study (MACS) was followed at 6 month intervals for 24 months to identify men who developed antibodies to HIV-1. Two hundred thirty-two men (8%) seroconverted. The highest attack rate was among men who reported practicing both receptive and insertive anal-genital intercourse. The attack rate among men who reported practicing receptive but not insertive intercourse was 3.6 times higher than among men practicing insertive intercourse although those practicing insertive only reported 38% more different partners. Only two men seroconverted who reported not practicing analgenital intercourse in the 12 month prior to the first antibody-positive visit. Because men were followed every 6 months, one of these men could have been infected within 6 months of the actual development of HIV-1 antibodies. The seroconversion rate was significantly lower among men who reported using condoms with all their partners. The results of this study (a) reaffirm that receptive anal-genital intercourse is the major route of infection among homosexual men of HIV-1, (b) suggest that there is a low risk of HIV-1 infection to the insertive partner in anal-genital intercourse, (c) suggest that infection may rarely occur through sexual activities other than anal-genital intercourse, (d) provide evidence that condoms as currently used by men in the MACS provide significant but not complete protection against HIV-1 infection, and (e) suggest that the number of men in the homosexual community engaging in high-risk behavior is declining.

Bisexuality↗
PubMed1988

Patterns of CD4+ cell changes after HIV-1 infection indicate the existence of a codeterminant of AIDS.

Successive interval slopes of CD4+ cells each constructed from levels at three consecutive 6 month visits were compared over 3 years of follow-up among 565 persistently HIV-1 antibody-positive, 326 persistently antibody-negative, and 51 seroconverting homosexual men who had at least 500 CD4+ cells/mm3 at baseline and completed the first three 6 month visits. "Change" was defined as a difference between two successive interval slopes. Sixty-two percent of seroconverters meeting these criteria experienced a shift in one or more of their successive CD4+ interval slopes, the majority (56%) from a level slope to a negative slope (decreasing numbers of CD4+ cells), a significantly greater proportion than that observed among seronegatives (30%, p less than 0.0001). Fifty-eight percent of the seropositives maintained level interval slopes over the 3 years of follow-up. The majority (59%) of those men experiencing a shift went from a level to a negative interval slope, a significantly greater proportion than observed among seronegatives (30%, p less than 0.0001). The observed patterns of change in interval slopes are consistent with the laboratory observation that CD4+ cells must be activated to replicate HIV-1. The use of the interval slope strategy provides a method to identify a temporal focal point at which to examine possible codeterminants that trigger the production of HIV-1 and the subsequent decline in CD4+ cells.

AIDS Serodiagnosis↗
PubMed1987

Predictors of clinical AIDS in young homosexual men in a high-risk area.

One hundred and sixty-seven homosexual men in Los Angeles characterized by HIV antibody, T-cell numbers, titres to cytomegalovirus (CMV), and specific sexual practices were followed for two years for immune changes and for more than three years for development of clinical AIDS. Thirty-five per cent had antibody to HIV at baseline. The mean level of T-helper (Th) cells was significantly lower and of T-suppressor (Ts) cells significantly higher in HIV seropositives than in seronegatives. The annualized incidence of HIV seroconversion was 7%. Eight men developed AIDS, an attack rate of 14% in those with HIV antibody at baseline. A number of observations were made: T-cell alterations, except a transient elevation in Ts cells, were unusual in the absence of HIV antibody; a seropositive man with a T-cell alteration was significantly less likely to revert to 'within normal limits' than was a seronegative man; a steady decline in the number of Th cells preceded onset of clinical AIDS; the number of Ts cells remained higher in men subsequently developing AIDS than in other seropositive men; clinical AIDS occurred only in men with HIV antibody whose CMV antibody levels were above the median for the group (1:1600); and the attack rate for clinical AIDS was 50% in men with HIV antibody and elevated CMV who at baseline had either: fewer than 325 Th cells/cc, or whose Th/Ts ratio was below 0.8 (but whose levels of Th and Ts cells were within normal limits).(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1987

A case-control study of osteosarcoma in young persons.

A study of 64 cases and 124 friend and neighbor controls was conducted to identify factors associated with the occurrence of osteosarcoma in young persons. Two types of information were collected: questionnaire data from telephone interviews with mothers, and data on height since birth from family, physician, and school records. Cases were not taller at the time of diagnosis than controls, nor were growth rates higher--either overall or during the 3-4 years prior to diagnosis. An excess risk, however, was observed among subjects whose birth length was at or below the 25th percentile, based on national standards. An excess risk was also found among subjects born more than one week early, but the positive association with short birth length remained when duration of pregnancy was taken into account. Positive associations were also found for prior trauma to the tumor site; congenital skeletal defects or other treated bone conditions; fetal x-ray; and maternal employment during pregnancy in manufacturing industries.

Adolescent↗
PubMed1987

Clinical manifestations of acute infection with human immunodeficiency virus in a cohort of gay men.

During a prospective study of the natural history of human immunodeficiency virus (HIV) infection in a cohort of gay/bisexual men, information on self-reported symptoms lasting for 3 or more days during the previous 6 months was collected without knowledge of the subject's HIV serological status. Twenty-two people were retrospectively found to have seroconverted to HIV during the interval. Each seroconverter was matched to two seronegative and two seropositive controls. Matched case-control analyses using the seronegative controls determined that the following symptoms lasting for 3 or more days were associated with new HIV infection: fever greater than 37.7 degrees C, swollen lymph nodes, night sweats and headaches. Matched case-control analyses using the seropositive controls determined that the following symptoms lasting for 3 or more days were associated with new HIV infection: fatigue, fever greater than 37.7 degrees C, swollen lymph nodes, night sweats and headaches. It was notable that the majority of seroconversions were not associated with any symptoms lasting for 3 or more days. Due to their non-specificity, symptoms associated with seroconversion are not likely to have a high positive predictive value. In high risk populations, however, appearance of these symptoms may facilitate identification of early infection that may be important for studies of natural history or for optimal timing for initiating antiviral therapy.

Fatigue↗
PubMed1985

Evoked potential testing in relatives of multiple sclerosis patients.

Evoked potential (EP) tests were obtained in 110 neurologically normal first-degree relatives of patients with multiple sclerosis. Visual EP tests were performed in all relatives; brainstem auditory and median nerve somatosensory EP tests were performed in 67 relatives. The relatives had a mean visual EP P100 latency that was significantly longer than that for normal subjects controlled for age and gender. Asymmetries were seen in results from individual MS relatives, including interocular visual EP P100 differences of up to 14 ms, and interarm somatosensory Erb-N18 differences of up to 3.0 ms. We identified 19 pairs of patients and relatives who were HLA identical and 18 other pairs who were HLA double nonmatched. EP asymmetries were seen more often in the HLA identical siblings than in the HLA double patients, especially if they share HLA types with the patients. Since less than 2% of siblings of MS patients would be expected to eventually develop clinical MS, these small subclinical electrophysiological changes are not expected to be a sign of the future appearance of clinical MS. Clinicians should be aware not to overinterpret small EP changes in relatives of MS patients.

Adolescent↗
PubMed1984

The relation of cytomegalovirus and Epstein-Barr virus antibodies to T-cell subsets in homosexually active men.

Eighty-nine homosexual men participated in a study of sexual practices, T-cell subsets, and antibody titers to cytomegalovirus (CMV) and Epstein-Barr virus (EBV). The prevalence of antibody to CMV was 96% and to EBV, 94%. Titers to CMV were higher in those practicing receptive anal intercourse. The CMV antibody titers were positively correlated with the T-helper/suppressor ratio, number of partners and venereal disease episodes, number of T-suppressor cells, and EBV titers. Twelve percent of the participants had a low ratio only, 18% T-suppressor augmentation, and 3% T-helper deficiency. The CMV titer and prevalence of receptive anal intercourse were higher in those with a low ratio only, T-suppressor augmentation, and T-helper deficiency. These results suggest that CMV infection is acquired through receptive anal intercourse and is associated with an increase in T-suppressor cells and, in some persons, a decrease in T-helper cells.

Adult↗
PubMed1984

Nontransmission of T-cell subset abnormalities from hemophiliacs to their spouses.

Hemophiliacs who are exposed to pooled clotting factor concentrate constitute one group at increased risk for development of acquired immune deficiency syndrome. To determine the prevalence of cellular immune aberrations in asymptomatic hemophiliacs, we studied a group of 65 adult hemophiliacs for T-cell subset abnormalities. Sixty-five percent of concentrate recipients had an abnormal T-helper to T-suppressor cell ratio, 40% had a depressed absolute T-helper cell level, and 29% had an elevated absolute T-suppressor cell count. To determine whether horizontal transmission of T-cell subset abnormalities from hemophiliacs to their female sexual partners occurred, we studied 41 spouses. We found no correlation between paired husband and wife values for T-cell ratio or any other immune parameter studied. There were no significant differences found between wives of hemophiliacs with reversed T-cell ratios and wives of hemophiliacs with T-cell ratios of 1.0 or greater, with respect to immunologic tests. We conclude that there is no evidence to date for heterosexual or household-contact transmission of T-cell subset abnormalities from hemophiliacs to their spouses in our study population.

Adolescent↗
PubMed1984

Application of simulation techniques for estimating duration of multiple sclerosis derived from prevalence-formed cohorts.

Comparisons of the average duration of multiple sclerosis derived from a prevalence survey of cases alive in 1970 in a low-risk area (Los Angeles County, California) and a high-risk area (King and Pierce Counties, Washington) suggest that patients in the high-risk area had a longer duration of disease than patients in the low-risk area. Because this finding was unexpected and because the underlying population of these two areas has been increasing at different rates, two simulation models were developed to estimate the duration of multiple sclerosis from a prevalence survey, taking into account the effects of changes in the population over time. Comparison of the durations derived from the two simulation studies suggested that underestimation of true backward recurrence time from the simulation studies was similar for the two study areas. Thus, the observed differences in duration between the two areas probably reflect the course of disease rather than differences in rate of growth of the two populations. These studies demonstrate the usefulness of simulation studies in estimating disease duration from cohorts derived from prevalence surveys of non-stable populations.

Adult↗
PubMed1984

Onset symptoms as predictors of mortality and disability in multiple sclerosis.

941 cases of definite/probable multiple sclerosis living in Los Angeles County, California and King and Pierce Counties, Washington in 1970 who had onset between 1960 and 1969 were followed for mortality and disability through 1980. Early age of onset and residence in Washington State were predictors of less rapid and severe subsequent course. Coordination symptoms at onset were prognostic of rapid progression to disability and/or early death, whereas early motor weakness was significantly predictive only for disability. The presence of sensory symptoms in addition to motor and/or coordination symptoms at onset, however, indicated a better prognosis than coordination and/or motor symptoms alone. This observation and the results of regression analyses indicated that specific groupings of symptoms at onset were more important for predicting course than the number of symptoms present at onset.

Adult↗