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Biomedical subjects

B F Polk

Publications and source records attributed to B F Polk.

At least 19 recordsLinked to original sources
PubMed1992

Markers of health status in an HTLV-I-positive cohort.

The health effects of chronic human T-cell lymphotropic virus type I (HTLV-I) infection were examined in a cohort of Japanese men who had emigrated from Okinawa, Japan, and had been participants in a prospective study in Hawaii since 1965. In the present follow-up study carried out in 1987-1988, various health indicators were measured in the subjects, whose mean age was 72.5 years. Participation rates were lower in the HTLV-I seropositives than in the seronegatives (46.7% vs. 76.0%) in the > or = 75-year age group. Lack of participation was significantly correlated with a high HTLV-I antibody titer. Among the participants, seropositive subjects were significantly more likely than the seronegatives to have lymphocytopenia (32.7% vs. 17.7%) and mild anemia (25.5% vs. 14.1%) after adjustment for age and socioeconomic status. The seropositives also had a higher frequency of acupuncture therapy (age-adjusted odds ratios were 2.1 and 4.2 for 1-5 treatments and > or = 6 treatments, respectively). Proportions of subjects who had been hospitalized at least twice were higher among the seropositives in the oldest age groups, 70-74 years and > or = 75 years, but not in those aged 65-69 years. Although specific disease conditions were not identified in this study, hematologic data, treatment histories, and the correlation between participation status and HTLV-I antibody titers suggest that chronic HTLV-I infection may be associated with as yet undefined adverse health effects, particularly in older age groups.

Acupuncture Therapy↗
PubMed1992

Predictors of the risk of development of acquired immunodeficiency syndrome within 24 months among gay men seropositive for human immunodeficiency virus type 1: a report from the Multicenter AIDS Cohort Study.

The natural history of infection with human immunodeficiency virus type 1 (HIV-1) is characterized by a relentless decline in CD4-positive lymphocytes and the ultimate development of acquired immunodeficiency syndrome (AIDS). However, variables other than the CD4-positive lymphocyte level contribute to the measurement of risk for AIDS and can be used as predictors of AIDS onset. This study was undertaken to identify factors that, independently of the CD4-positive lymphocyte level, would predict the risk of AIDS over 24 months in a cohort of HIV-1 seropositive homosexual men receiving no antiretroviral therapy. Demographic, clinical, and laboratory data from 1,325 white, HIV-1 seropositive participants in the Multicenter AIDS Cohort Study who have been studied for 4 years were analyzed with univariate and multivariate methods. To control for stage of infection, the baseline percentage of CD4-positive lymphocytes (a known marker of disease progression), and the decline of CD4-positive cells during the first 6 months of observation were used as continuous variables. The variables that were independently associated with an increased risk of developing AIDS were: low baseline CD4 percentage, decline in the CD4 percentage during the first 6 months of follow-up, the presence of serum immunoglobulin A at baseline, decrease in hemoglobin during the first 6 months of follow-up, incident fatigue, and the interaction of decline in the CD4 percentage and incident thrush. While low CD4 percentage and other variables have been previously described as prognostic markers, decline in the CD4 percentage and the interaction of that decline and incident thrush have not previously been described as being of prognostic importance. These variables and the analytic method for estimating prognosis may prove useful for selecting and evaluating antiretroviral therapy, instituting prophylactic measures against certain opportunistic infections, and recruitment into clinical trials. Because study participants received no antiretroviral prophylaxis during the period under analysis, the method could be used to estimate the prognosis for those receiving investigational treatment were they to remain untreated, effectively making any participant in a clinical trial his own untreated control.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Declining seroprevalence and transmission of HTLV-I in Japanese families who immigrated to Hawaii.

This study examined the seroprevalence and transmission of human T cell lymphotropic virus type I (HTLV-I) in Japanese families who originated in Okinawa, an area in which HTLV-I is endemic, and who were currently residing in Hawaii, a nonendemic area. Among a cohort of Japanese men whose sera were collected in Hawaii in 1967-1975, those of Okinawan ancestry had an HTLV-I seroprevalence of 11.4%. This study, conducted in 1987-1988, sampled 142 index subjects from this male cohort and tested them along with their wives, children, and spouses of the children for HTLV-I antibodies. Seropositivity in their wives was 11.4% and 41.2% among the seronegative and seropositive index subjects, respectively; seropositivity also increased from 29.4% to 35.3% to 58.8% with the husbands' increasing antibody levels by tertiles. Elevated antibody levels may be a marker for infectivity, which is associated with more efficient sexual transmission of HTLV-I. The age-adjusted odds ratio for the association of seropositivity between husband and wife, however, was four times lower than that reported among native Okinawans. In addition, a substantially low seroprevalence (1.3%) was found among their offspring. The decline in HTLV-I transmission in this migrant population may be due to low infectivity in the parent generation who live in a nonendemic environment, increasing numbers of offspring marrying outside of the Okinawan community, and improved living circumstances.

Aged↗
PubMed1991

Epstein-Barr virus antibody patterns preceding the diagnosis of non-Hodgkin's lymphoma.

Immunosuppressed patients who develop non-Hodgkin's lymphoma (NHL) have abnormal antibody responses against the Epstein-Barr virus (EBV) prior to the diagnosis of malignancy. To see if this is also true of "spontaneous" cases in the general population, we undertook a collaborative serologic case-control study. From 4 serum banks containing specimens from over 240,000 persons, 104 subjects were identified for whom a blood specimen had been stored an average of 63 months before diagnosis of NHL, and 259 controls matched for age, sex, ethnic group and date of serum collection. The relative risks (RR) for subsequent development of NHL associated with elevated levels of IgG and IgM antibodies against viral capsid antigen were 2.5 (95% confidence interval = 1.1-5.7) and 3.2 (1.3-7.5), respectively; these associations increased with age at diagnosis. For the nuclear antigen, the distribution of titers for cases was more restricted than that of controls, with fewer cases having either elevated or low titers, RR = 0.5 (0.2-1.4) and 0.5 (0.2-1.2), respectively. Cases had significantly lower antibody titers against the cytomegalovirus, RR = 0.4 (0.2-0.9). These findings suggest that, at least for some patients, NHL is preceded by an enhanced level of endogenous immunosuppression with resultant EBV activation. This observation supports the role of EBV either directly in the development of NHL or as a primary marker of immune dysfunction.

Adult↗
PubMed1991

Epstein-Barr virus antibody patterns preceding the diagnosis of nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) patients have elevated IgG and IgA antibody titers against the Epstein-Barr viral capsid antigen (VCA) and the diffuse component of the early antigen complex (EA-D) at diagnosis. Several studies have implied that the presence of anti-VCA-IgA can be used as a screening marker for early NPC. To evaluate this further, we undertook a serologic case-control study based on four serum banks which together had specimens from over 240,000 persons. Seven cases of undifferentiated or poorly differentiated NPC were diagnosed in the period after serum collection ranging from 26 months to 154 months. Two controls per case matched on serum bank, age, sex, race, and date of serum collection were selected by a predetermined random process. For anti-VCA-IgG, the geometric mean titer for cases (88.3) was significantly higher than that for controls (75.5, P less than 0.05). The difference was greatest among the Asian patients. No significant differences were found for anti-VCA-IgA, anti-EA-D, and anti-EA-R or anti-EBNA. No time effects were evident when titers were plotted against time of blood collection preceding diagnosis. Our results do not suggest EBV activation in the period preceding NPC diagnosis, nor that detectable IgA antibody against VCA is a marker for early disease.

Adult↗
PubMed1990

Serologic precursors of cancer. Retinol, carotenoids, and tocopherol and risk of prostate cancer.

We investigated the associations of serum retinol, the carotenoids beta-carotene and lycopene, and tocopherol (vitamin E) with the risk of prostate cancer in a nested case-control study. For the study, serum obtained in 1974 from 25,802 persons in Washington County, MD, was used. Serum levels of the nutrients in 103 men who developed prostate cancer during the subsequent 13 years were compared with levels in 103 control subjects matched for age and race. Although no significant associations were observed with beta-carotene, lycopene, or tocopherol, the data suggested an inverse relationship between serum retinol and risk of prostate cancer. We analyzed data on the distribution of serum retinol by quartiles, using the lowest quartile as the reference value. Odds ratios were 0.67, 0.39, and 0.40 for the second, third, and highest quartiles, respectively.

Aged↗
PubMed1990

Risk factors for preterm premature rupture of fetal membranes: a multicenter case-control study.

To assess the association between women with preterm premature rupture of membranes and 41 potential risk factors, we conducted a case-control study in six United States tertiary perinatal centers. The study involved completion of a comprehensive questionnaire for 341 women with preterm premature rupture of membranes in singleton pregnancies from 20 to 36 weeks' gestation and 253 control women matched for maternal age, gestational age, parity, clinic or private patient status, and previous vaginal or cesarean delivery. Univariate analysis revealed 11 variables associated with a significantly (p less than 0.05) increased risk of preterm premature rupture of membranes. After multiple logistic regression analysis, three variables remained in the model as independent risk factors: antepartum vaginal bleeding in more than one trimester (odds ratio 7.4; 95% confidence interval, 2.2, 25.6), current cigarette smoking (odds ratio, 2.1; 95% confidence interval, 1.4, 3.1), and previous preterm delivery (odds ratio, 2.5; 95% confidence interval, 1.4, 2.5). Cessation of cigarette smoking by pregnant women may reduce the risk of preterm premature rupture of membranes. Further study is necessary to determine the nature of the relationship between antepartum vaginal bleeding and preterm premature rupture of membranes.

Case-Control Studies↗
PubMed1990

Seasonal and annual variation of antibody to HIV-1 among male inmates entering Maryland prisons: update.

Previous serosurveys of antibody to HIV-1 among incoming male inmates in Maryland between April and June of 1985, 1986 and 1987 have shown a prevalence of 7.0, 7.7 and 7.0%, respectively, with stability persisting after multivariate adjustment. To investigate seasonality and update annual trends, excess sera were obtained from incoming male inmates between August 1987 and August 1988. Correctional personnel also provided demographic variables of age, race, offense, category, and jurisdiction. Once rendered anonymous, specimens were assayed for antibody to HIV-1 using enzyme-linked immunosorbent assay and Western blot. For the 12-month study period, 415 (7.9%) of 5262 consecutive male entrants were seropositive. On univariate and multivariate analyses, no significant change in seroprevalence or risk by subgroup was noted by month or season. For data from April to June 1988, 113 (8.1%) of 1398 consecutive entrants demonstrated anti-HIV-1; seropositivity was associated with age greater than 25 years, Black race, and Baltimore jurisdiction. No significant change was found over time in seroprevalence or risk of HIV-1 infection by subgroup in multivariate analysis combining data for 1985-1988. These data provide additional evidence to suggest stability of HIV-1 seroprevalence in Maryland male prison entrants.

Acquired Immunodeficiency Syndrome↗
PubMed1990

The effect of fresh lymphocytes on increased sensitivity of HIV-1 isolation: a multicenter study.

A multicenter study was undertaken to determine the sensitivity and reproducibility of markers for human immunodeficiency virus type 1 (HIV-1) viral growth and the effect of various preparations of lymphocytes on the sensitivity of standard and routinely used procedures for HIV-1 isolation. In phase 1, cocultivated culture supernatants obtained from 10 HIV-1 cultures were transported to three Multicenter AIDS Cohort Study (MACS) Virology Laboratories. Three commercial HIV-p24 antigen capture (AC) tests and two reverse transcriptase (RT) assays were used to ascertain the replication of HIV-1. The Du Pont and Abbott AC assays were found to be most sensitive (85-100%), and the RT assay with 24-h incubation period had comparable sensitivity (75-100%). In phase II, the sensitivity of standard cocultivation procedure for HIV-1 isolation was compared using freshly phytohemagglutinin-P (PHA-P)-stimulated, stimulated-frozen, and frozen-thawed and then stimulated normal human peripheral blood mononuclear cells (PBMCs) as cocultivating cells. Blood samples from 13 HIV-1 infected individuals with various CD4+ cell counts were cocultivated in each of the three MACS laboratories using one of the aforementioned normal PBMCs. The PHA-P-stimulated fresh normal PBMC showed a maximum isolation rate of 100% (13 of 13) with an average of 8 days to positivity. This rate of isolation was significantly greater than other rates using any one of the other PBMC preparations. These findings demonstrated that the use of freshly PHA-P stimulated PBMCs maximized HIV-1 isolation from blood when a sensitive HIV-1 p24 AC assay or RT assay with overnight incubation is employed for the detection of HIV in culture supernatant.

Blood Preservation↗
PubMed1990

HIV-1, sexual practices, and contact with foreigners in homosexual men in Colombia, South America.

From October 1985 to November 1987, a sample of 294 Colombian homosexual men volunteered to answer a questionnaire on sexual practices and consented to HIV-1 testing. Testing for HIV-1 was performed using an ELISA and those positive were confirmed with envelope- and core-specific ELISAs. Statistical methods for data analysis included Mantel-Haenszel methods on contingency tables. The overall seropositivity rate was 21.1%. Subjects who reported a receptive role (either as predominantly receptive or as mixed receptive-insertive intercourse) had a seropositivity rate of 23.7%, which was significantly higher than the 10.3% found in those reporting predominantly insertive intercourse (RR = 2.30, 95% C.I. = 1.16-4.57). For subjects reporting receptive intercourse, sexual contact with foreign visitors was a significant risk factor for HIV-1 infection (RR = 1.84, 95% C.I. = 1.13-3.00). Factors of borderline significance included having had more than ten homosexual partners in the preceding year (RR = 1.53) and a history of international travel (RR = 1.43). These associations did not hold for those reporting predominantly insertive intercourse. The data indicate the need to monitor the spread of HIV-1 at the international level and provide information on subgroups of high transmission rates.

Adult↗
PubMed1990

Incidence of Kaposi's sarcoma in a cohort of homosexual men infected with the human immunodeficiency virus type 1. The Multicenter AIDS Cohort Study Group.

Longitudinal data on 2,125 participants in the Multicenter AIDS Cohort Study (MACS) with documented antibodies to the human immunodeficiency virus type 1 (HIV-1) were used to examine the incidence of acquired immune deficiency syndrome (AIDS)-related Kaposi's sarcoma (KS) over time and to determine if sexual practices and hematologic variables prior to diagnosis differed for participants who develop KS vs. non-KS AIDS (NKS). In the first 4 years of the study, 84 seropositive men were observed to develop KS and 307 presented with an AIDS diagnosis other than KS. A systematic trend in the incidence of KS over time was not apparent in this population. The number of anal-receptive intercourse partners prior to diagnosis declined in a similar fashion for both AIDS groups. Although the number of partners with whom the men performed rimming decreased prior to diagnosis for both AIDS groups, a greater proportion of the KS AIDS group had performed this activity with multiple partners than had the non-KS AIDS group. Furthermore, history of oral gonorrhea was significantly (p = 0.027) more prevalent in the KS group. In addition, the KS AIDS group had lower cytomegalovirus antibody levels prior to diagnosis and higher levels of total immunoglobulin G. The groups did not differ with respect to baseline hematological measures, temporal trends in helper and suppressor T cells, or hepatitis B surface antigen or antibody. Given this profile of factors associated with the occurrence of KS, an infectious agent, in addition to HIV-1, is plausible as a proposed cofactor in the development of KS.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Seroepidemiology of hepatitis B virus infection in the United States. 1976 to 1980.

The prevalence of hepatitis B virus (HBV) infection was determined using sera from persons participating in the second National Health and Nutrition Examination Survey, conducted from 1976 to 1980. Of 14,488 scientifically selected participants aged 12 to 74, 821 had evidence of past or present infection with HBV. In the white population, the weighted estimate of hepatitis B infection was 3.2 percent (95 percent confidence interval, 3.1 to 4.2). A steady increase with age was seen; by ages 65 to 74, the prevalence was 6.9 percent (95 percent confidence interval, 5.2 to 8.5). In the black population, the overall weighted estimate of prevalence was 13.7 percent (95 percent confidence interval, 11.6 to 15.8). In this racial group, there was a dramatic increase with age, with the oldest age groups having a prevalence of 39.6 percent (95 percent confidence interval, 29.1 to 50.0). In both racial groups, there was a low prevalence of infection in young children that began to rise between ages 12 and 18. In a multivariate analysis of factors associated with infection, there was an interaction of race with age; therefore, the odds ratio for race is presented for four ages. This ratio ranged from 3.0 (95 percent confidence interval, 1.8 to 4.2) for a 15-year-old to 8.2 (95 percent confidence interval, 6.5 to 10.3) for a 70-year-old. These relative odds estimates were not substantially affected by adjustment for the available information on risk factors for HBV infection. The results of this study in a representative sample of the United States population show that adult black Americans are at high risk for hepatitis B infection. Other independent predictors of HBV positivity include male sex; residing in the South, Northeast, or West; residing in a city of 250,000 or more people; serving in the armed forces; living below the poverty level; and having a positive treponemal test for syphilis. These data suggest that the immunization practices for controlling this disease should be re-examined.

Adolescent↗
PubMed1989

Relationship between carotenoids and cancer. The Multiple Risk Factor Intervention Trial (MRFIT) Study.

We evaluated the baseline serum levels of beta carotene, total carotenoids, vitamin A and E, and retinol-binding protein among 156 initially healthy men who participated in the Multiple Risk Factor Intervention Trial (MRFIT) and who subsequently died of cancer and 311 controls individually matched for age, smoking status, randomization group, date of randomization, and clinical center. Both total carotenoids and beta carotene levels were lower in the 66 lung cancer cases than in their matched controls. For all cancer deaths combined, there were no significant differences in total carotenoids or beta carotene between cases and controls. The relationship between lower serum carotenoid levels and lung cancer persisted after adjusting for the number of cigarettes, alcohol intake, serum thiocyanate levels, and cholesterol levels in the blood. Serum levels of retinol, alpha tocopherol, and retinol-binding protein were not related to any cancer site. The results of this study provide further evidence for a possible protective effect of beta carotene against lung cancer among cigarette smokers.

Adult↗
PubMed1989

Hodgkin's disease and Epstein-Barr virus. Altered antibody pattern before diagnosis.

In patients with Hodgkin's disease, titers of IgG antibody against viral capsid antigen of Epstein-Barr virus and the prevalence of antibodies against early antigen are higher than expected. To evaluate whether this condition antedates diagnosis, we identified 43 persons with Hodgkin's disease, from whom blood had been drawn and stored for an average of 50.5 months before diagnosis, and 96 controls from the same populations, from whom blood had been drawn at the same time. The relative risks of Hodgkin's disease associated with elevated levels of IgG and IgA antibodies against capsid antigen were 2.6 (90 percent confidence interval, 1.1 to 6.1) and 3.7 (1.4 to 9.3), respectively. For Epstein-Barr nuclear antigen, the relative risk was 4.0 (1.4 to 11.4), and for early antigen D it was 2.6 (1.1 to 6.1). However, the prevalence of IgM antibody against capsid antigen was substantially lower in patients with Hodgkin's disease (0.22 [0.04 to 1.3]). These associations were stronger in serum samples obtained at least three years before diagnosis than in serum samples obtained closer to diagnosis. We conclude that the development of Hodgkin's disease may in some patients be preceded by enhanced activation of Epstein-Barr virus. Whether Epstein-Barr virus has a direct role in the pathogenesis of the disease or is simply a marker for a more fundamental factor affecting the immune control of latent infections is unknown.

Antibodies, Viral↗
PubMed1989

Development of antibodies to HIV-1 is associated with an increase in circulating CD3+CD4-CD8- lymphocytes.

This study investigated whether seroconversion with respect to human immunodeficiency virus, type 1 (HIV-1) was associated with an increase in lymphocytes expressing the CD3+CD4-CD8- phenotype. Proportions and absolute numbers of CD3+, CD4+, and CD8+ lymphocytes were determined prospectively over a 2.5-year period on 4954 homosexual and/or bisexual men participating in the Multicenter AIDS Cohort Study. Of the 4808 men whose serostatus at entry could be verified, 1745 were seropositive (SP) for antibodies to HIV-1 at entry into study, 2795 were uniformly seronegative (SN) for HIV-1 for 30 months, and 268 were seroconverters (SC) with respect to HIV-1 during this period. For each of six semiannual evaluations, proportions and numbers of CD3+CD4-CD8- lymphocytes (calculated as CD3- (CD4 + CD8] were both significantly greater in the SP group than in the SN group (P less than 0.001). Mean CD3+CD4-CD8- levels in the SC group were indistinguishable from those in the SN group before seroconversion, but by 3-9 months after seroconversion the SC group demonstrated absolute numbers of CD3+CD4-CD8- lymphocytes which were significantly increased (P less than 0.001) compared to the SN group using linear regression methods with adjustment for correlation of measurements within an individual over time. An additional significant increase occurred by 21-27 months after seroconversion (P = 0.006). These results are consistent with an association of HIV-1 seroconversion with an increase in circulating T lymphocytes expressing the CD3+CD4-CD8- phenotype (double negative T cells), a decrease in CD3-CD4-CD8+ natural killer cells, or both. An increase in double negative T cells could reflect a host defense mechanism against HIV-1 or effects of HIV-1 on T cell development.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Limiting dilution analysis of in vivo-activated (IL-2 responsive) peripheral blood lymphocytes in HIV-1-infected subjects.

The progression of infection with human immunodeficiency virus, type 1 (HIV-1), is associated with a loss of helper T cell function, but the mechanism for this loss (e.g., decreased absolute number of helper cells, altered function of helper cells, or both) has not been delineated. Many studies have suggested that T-cell production of and/or responsiveness to the T cell growth factor interleukin-2 (IL-2) declines over the course of HIV-1 infection. Using a highly quantitative 6-day limiting dilution assay (LDA), we investigated whether the number and the proliferative capacity of circulating IL-2 responsive cells in patients with AIDS differ from those in patients in earlier stages of HIV-1 infection (asymptomatic or AIDS-related complex) and healthy seronegative individuals. The frequency of IL-2 responsive cells declined progressively in asymptomatic seropositive subjects, those with ARC, and those with AIDS. In contrast, the proliferative capacity of individual IL-2 responsive cells, as reflected by the magnitude of thymidine uptake per precursor, was reduced only in patients with frank AIDS and was normal in asymptomatic subjects and in those with ARC. These results suggest that the development of AIDS in the setting of HIV-1 infection may reflect a combination of qualitative as well as quantitative changes in lymphocyte function. They also suggest that analysis of lymphocyte responsiveness to IL-2 may provide a useful approach to prediction of the development of AIDS in individuals infected with HIV-1.

Acquired Immunodeficiency Syndrome↗