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Biomedical subjects

R H Byers

Publications and source records attributed to R H Byers.

At least 19 recordsLinked to original sources
PubMed2005

Chronic herpes simplex virus type-2 infection and HIV viral load.

By December 2003, the estimated adult HIV/AIDS prevalence rate in sub-Saharan Africa was 7.5-8.5%, and rates of herpes simplex virus type-2 (HSV-2) infection among adults aged >30 years ranged from 60% to 82%. However, little is known about the natural history of HIV/HSV-2 co-infection in this population. We evaluated HIV viral load and CD4+ cell counts among persons with and without chronic HSV-2 co-infection in a cross-sectional study of HIV-infected persons not receiving antiretroviral therapy. HSV-2 and HIV co-infection was associated with a 0.3 log copies/mL higher HIV viral load compared with persons without HSV-2 infection (P=0.014). Chronic HSV-2 infection may have a negative effect on the clinical course of persons with HIV.

Adult↗
PubMed2001

A method for classification of HIV exposure category for women without HIV risk information.

An increasing number of cases of human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) among women is reported to state and territorial health departments without exposure risk information (i.e., no documented exposure to HIV through any of the recognized routes of HIV transmission). Because surveillance data are used to plan prevention and other services for HIV-infected persons, developing methods to accurately estimate exposure risk for HIV and AIDS cases initially reported without risk information and assisting states to analyze and interpret trends in the HIV epidemic by exposure risk category is important. In this report, a classification model using discriminant function analysis is described. The purpose of the classification model is to develop a proportionate distribution of exposure risk category for cases among women reported without risk information. The distribution was estimated based on behavioral and demographic data obtained from interviews with HIV-infected women; the interviews were conducted in 12 states during 1993-1996. Variables used in the analysis were alcohol abuse, noninjection-drug use, and crack use; year of HIV/AIDS diagnosis; age; employment; and region. As a result of the classification procedure, nearly all cases among women with no reported risk were classified into an exposure risk category: 81%, heterosexual contact; and 16%, injection-drug use. These proportions are higher than the current redistribution fractions (calculated from risk reclassification patterns and weighted by demographic characteristics) and reflect the increasing proportion of cases among women attributable to heterosexual contact with an infected partner. This report provides one method that could be applied to HIV surveillance data at the national level to estimate the proportion of cases in exposure risk categories. However, because the study in this report is limited in sample size and geographic representativeness, other models are also needed for adjusting risk exposure data at the national, state, and local levels.

Adult↗
PubMed2000

Prevention of HIV infection in street-recruited injection drug users. The Collaborative Injection Drug User Study (CIDUS).

BACKGROUND: Injection drug users (IDUs) and their sex partners account for an increasing proportion of new AIDS and HIV cases in the United States, but public debate and policy regarding the effectiveness of various HIV prevention programs for them must cite data from other countries, from non-street-recruited IDUs already in treatment, or other programs, and from infection rates for pathogens other than HIV. METHODS: Participants were recruited from the street at six sites (Baltimore [Maryland], New York [two sites], Chicago [Illinois], San Jose [California], Los Angeles [California], and at a state women's correctional facility [Connecticut]), interviewed with a standard questionnaire, and located and reinterviewed at one or more follow-up visits (mean, 7.8 months later). HIV serostatus and participation in various programs and behaviors that could reduce HIV infection risk were determined at each visit. RESULTS: In all, 3773 participants were recruited from the street, and 2306 (61%) were located and interviewed subsequently. Of 3562 initial serum specimens, 520 (14.6%) were HIV-seropositive; at subsequent assessment, 19 people, all from the East Coast and Chicago, had acquired HIV. Not using previously used needles was substantially protective against HIV acquisition (relative risk [RR], 0.29; 95% confidence interval [CI], 0.11-0.80 ) and, in a multivariate model, was significantly associated with use of needle and syringe exchange programs (adjusted odds ratio [ORadj], 2.08; 95% CI, 1.15-3.85). Similarly, reduction of injection frequency was very protective against seroconversion (RR, 0.33; 95% CI, 0.14-0.80), and this behavior was strongly associated with participation in drug treatment programs (ORadj, 3.54; 95% CI, 2.50-5.00). In a separate analysis, only 37.5% of study-participants had sufficient new needles to meet their monthly demand. CONCLUSIONS: In this large multicity study of IDUs in the United States, several HIV prevention strategies appeared to be individually and partially effective; these results indicate the continued need for, and substantial gaps in, effective approaches to preventing HIV infection in drug users.

Adult↗
PubMed2000

Influence of human immunodeficiency virus infection on pelvic inflammatory disease.

OBJECTIVE: To examine the influence of human immunodeficiency virus (HIV) infection on clinical and microbiologic characteristics of pelvic inflammatory disease (PID). METHODS: Forty-four HIV-infected women and 163 HIV noninfected women diagnosed with PID by standard case definition were evaluated by using clinical severity scores, transabdominal sonograms, and endometrial biopsies. After testing for bacterial infections, patients were prescribed antibiotics as recommended by the Centers for Disease Control and Prevention (CDC). RESULTS: Symptoms of PID and analgesic use before enrollment did not differ by HIV serostatus. More HIV-infected women had received antibiotics before enrollment (40.9% versus 27.2%, P =.08), a factor associated with milder signs regardless of serostatus. More HIV-infected women had sonographically diagnosed adnexal masses at enrollment (45.8% versus 27.1%, P =.08), a difference that yielded higher median severity scores (17.5 of 42 points versus 15 of 42 points, P =.07). However, those differences were not significant at the P <.05 level. Mycoplasma (50% versus 22%, P <.05) and streptococcus species (34% versus 17%, P <.05) were isolated more commonly from biopsies of HIV-infected women. Within 30 days after enrollment, HIV-infected women generally responded as well to therapy as HIV-noninfected women did, regardless of initial CD4 T-lymphocyte percentage. CONCLUSION: Among women with acute PID, HIV infection was associated with more sonographically diagnosed adnexal masses. Clinical response to CDC-recommended antibiotics did not differ appreciably by serostatus. Mycoplasmas and streptococci were isolated more commonly from HIV-infected women, but those organisms also might be associated with PID in immunocompetent women.

Adult↗
PubMed2000

Epidemiology of HIV/AIDS in children.

HIV infection has been a major cause of morbidity and mortality since the first cases of AIDS among children were reported in 1982 in the United States. Considerable advances, especially in the past 5 years, in the understanding of the pathogenesis, diagnosis, treatment, monitoring, and prevention of HIV infection in children have changed the rate of pediatric HIV infection in the United States. Efforts to maximally decrease perinatal HIV transmission in the United States are ongoing. Physicians must try to prevent HIV infection among women, especially adolescents.

AIDS-Related Opportunistic Infections↗
PubMed1999

Trends in perinatal transmission of HIV/AIDS in the United States.

CONTEXT: Since 1994, the US Public Health Service (PHS) has recommended routine, voluntary prenatal human immunodeficiency virus (HIV) testing and zidovudine therapy to reduce perinatal HIV transmission. OBJECTIVE: To describe trends in incidence of perinatal AIDS and factors contributing to these trends, particularly the effect of PHS perinatal HIV recommendations. DESIGN, SETTING, AND PARTICIPANTS: Analysis of nationwide AIDS surveillance data and data from HIV-reporting states through June 1998. MAIN OUTCOME MEASURES: Trends in AIDS by year of diagnosis, incidence rates of AIDS and Pneumocystis carinii pneumonia (PCP) among infants younger than 1 year from US natality data for birth cohorts 1988 to 1996; expected number of infants with AIDS from national serosurvey data; and zidovudine use data from selected HIV-reporting states. RESULTS: Perinatal AIDS cases peaked in 1992 and then declined 67% from 1992 through 1997, including an 80% decline in infants and a 66% decline in children aged 1 to 5 years. Rates of AIDS among infants (per 100000 births) declined 69%, from 8.9 in 1992 to 2.8 in 1996 compared with a 17% decline in births to HIV-infected women from 1992 (n = 6990) to 1995 (n = 5797). Among infants, PCP rates per 100000 declined 67% (from 4.5 in 1992 to 1.5 in 1996), similar to the decline in other AIDS conditions. The percentage of perinatally exposed children born from 1993 through 1997 whose mothers were tested for HIV before giving birth increased from 70% to 94%; the percentage who received zidovudine increased from 7% to 91%. CONCLUSIONS: According to these data, substantial declines in AIDS incidence were temporally associated with an increase in zidovudine use to reduce perinatal HIV transmission, demonstrating substantial success in implementing PHS guidelines. Reductions in the numbers of births and effects of therapy in delaying AIDS do not explain the decline.

AIDS-Related Opportunistic Infections↗
PubMed1999

Sister chromatid exchange data fit with a mixture of Poisson distributions.

Bowman et al. [K.O. Bowman, Wesley Eddings, Marvin A. Kastenbaum, L. R. Shenton. Sister chromatid exchange data and Gram-Charlier series, Mutat. Res., 403 (1998) 159-169.] have shown that a Gram-Charlier modification of a negative binomial distribution gives a reasonable fit to counts of sister chromatid exchange (SCE) data originally presented by Bender et al. [M.A. Bender, R.J. Preston, R. C. Leonard, B.E. Pyatt, P.C. Gooch, On the distribution of spontaneous SCE in human peripheral blood lymphocytes, Mutat. Res., 281 (1992) 227-232. ]. Here we show that a mixture of a generalized Poisson distributions also fits the data. Advantages of the generalized Poisson mixture include a simplified model involving only four parameters which fits the data more closely according to the chi-squared goodness-of-fit criterion.

Female↗
PubMed1998

Efficacy of risk-reduction counseling to prevent human immunodeficiency virus and sexually transmitted diseases: a randomized controlled trial. Project RESPECT Study Group.

CONTEXT: The efficacy of counseling to prevent infection with the human immunodeficiency virus (HIV) and other sexually transmitted diseases (STDs) has not been definitively shown. OBJECTIVE: To compare the effects of 2 interactive HIV/STD counseling interventions with didactic prevention messages typical of current practice. DESIGN: Multicenter randomized controlled trial (Project RESPECT), with participants assigned to 1 of 3 individual face-to-face interventions. SETTING: Five public STD clinics (Baltimore, Md; Denver, Colo; Long Beach, Calif; Newark, NJ; and San Francisco, Calif) between July 1993 and September 1996. PARTICIPANTS: A total of 5758 heterosexual, HIV-negative patients aged 14 years or older who came for STD examinations. INTERVENTIONS: Arm 1 received enhanced counseling, 4 interactive theory-based sessions. Arm 2 received brief counseling, 2 interactive risk-reduction sessions. Arms 3 and 4 each received 2 brief didactic messages typical of current care. Arms 1, 2, and 3 were actively followed up after enrollment with questionnaires at 3, 6, 9, and 12 months and STD tests at 6 and 12 months. An intent-to-treat analysis was used to compare interventions. MAIN OUTCOME MEASURES: Self-reported condom use and new diagnoses of STDs (gonorrhea, chlamydia, syphilis, HIV) defined by laboratory tests. RESULTS: At the 3- and 6-month follow-up visits, self-reported 100% condom use was higher (P<.05) in both the enhanced counseling and brief counseling arms compared with participants in the didactic messages arm. Through the 6-month interval, 30% fewer participants had new STDs in both the enhanced counseling (7.2%; P= .002) and brief counseling (7.3%; P= .005) arms compared with those in the didactic messages arm (10.4%). Through the 12-month study, 20% fewer participants in each counseling intervention had new STDs compared with those in the didactic messages arm (P = .008). Consistently at each of the 5 study sites, STD incidence was lower in the counseling intervention arms than in the didactic messages intervention arm. Reduction of STD was similar for men and women and greater for adolescents and persons with an STD diagnosed at enrollment. CONCLUSIONS: Short counseling interventions using personalized risk reduction plans can increase condom use and prevent new STDs. Effective counseling can be conducted even in busy public clinics.

Adolescent↗
PubMed1998

Projection of AIDS and HIV incidence among children born infected with HIV.

By 31 December 1995, 6285 children with perinatally acquired immunodeficiency syndrome (AIDS) had been reported to the Centers for Disease Control and Prevention (CDC) by the state and local health departments of all 50 states, the District of Columbia, Puerto Rico, and the U.S. territories. We present here the statistical methods used to estimate the number of infants born with HIV and to predict the number of diagnoses of perinatally acquired AIDS among children to 1997. We estimate that there were 13,900 children who had perinatally acquired HIV infection by the end of 1995 and who will eventually be reported with AIDS. If 85 per cent of all diagnoses are reported, this represents a total of more than 16,300 diagnoses. Of these, 6600 had developed AIDS by the end of 1995 and will eventually be reported to CDC. We project that, during 1996 and 1997, another 1500 HIV-infected children will be born.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Prevalence and incidence of vertically acquired HIV infection in the United States.

OBJECTIVE: To estimate human immunodeficiency virus (HIV) type I prevalence among childbearing women, HIV incidence in infants, and the number of children living with HIV infection and acquired immunodeficiency syndrome as a result of transmission from mother to infant (vertical transmission). DESIGN: The national HIV serosurvey of childbearing women was used to estimate the incidence of vertically acquired HIV infection in children born between 1988 and 1993. Data from the national acquired immunodeficiency syndrome case surveillance system and a multicenter pediatric HIV surveillance project were modeled to estimate incidence in children born between 1978 and 1987. SETTING: Surveillance conducted by the Centers for Disease Control and Prevention, Atlanta, Ga, in collaboration with state and local health departments. RESULTS: Approximately 14,920 HIV-infected infants were born in the United States between 1978 and 1993. Of these, an estimated 12,240 children were living at the beginning of 1994; 26% were younger than 2 years, 35% were aged 2 to 4 years, and 39% were aged 5 years or older. Approximately 6530 HIV-infected women gave birth in the United States in 1993, and, based on a 25% vertical transmission rate, an estimated 1630 of their infants were HIV infected. CONCLUSIONS: These results provide a basis for estimating medical and other resource needs for HIV-infected women and their children and for measuring the impact of interventions to reduce vertical transmission of HIV.

AIDS Serodiagnosis↗
PubMed1994

The types of drugs used by HIV-infected injection drug users in a multistate surveillance project: implications for intervention.

OBJECTIVES: This study sought to describe the drugs used by drug injectors infected with human immunodeficiency virus (HIV) and to determine factors associated with the primary injection drug used. METHODS: A cross-section of persons 18 years of age or older reported with HIV or acquired immunodeficiency syndrome (AIDS) to local health departments in 11 US states and cities was surveyed. RESULTS: Of 4162 persons interviewed, 1147 (28%) reported ever having injected drugs. Of these 1147 injectors, 72% primarily injected a drug other than heroin. However, the types of drugs injected varied notably by place of residence. Heroin was the most commonly injected drug in Detroit (94%) and Connecticut (48%); cocaine was the most common in South Carolina (64%), Atlanta (56%), Delaware (55%), Denver (46%), and Arizona (44%); speedball was most common in Florida (46%); and amphetamines were most common in Washington (56%). Other determinants of the type of drug primarily injected were often similar by region of residence, except for heroin use. Polysubstance abuse was common; 75% injected more than one type of drug, and 85% reported noninjected drug use. CONCLUSIONS: Preventing the further spread of HIV will require more drug abuse treatment programs that go beyond methadone, address polysubstance abuse, and adapt to local correlates of the primary drug used.

Adolescent↗
PubMed1993

Epidemiology of human immunodeficiency virus type 1 infection among homosexual men participating in hepatitis B vaccine trials in Amsterdam, New York City, and San Francisco, 1978-1990.

Homosexual/bisexual men from Amsterdam, The Netherlands, New York, New York, and San Francisco, California, were entered into trials of the efficacy of hepatitis B vaccine shortly before the acquired immunodeficiency syndrome (AIDS) epidemic was recognized (1978-1980). The authors analyzed data, including serial blood samples tested for antibody to human immunodeficiency virus type 1 (HIV-1) as well as demographic and behavioral information, to characterize the spread of HIV-1 infection within the cohorts. By the end of 1982, the cumulative incidence of HIV-1 infection within the cohorts. By the end of 1982, the cumulative incidence of HIV-1 infection was 7.5% in Amsterdam, 26.8% in New York City, and 42.6% in San Francisco. Covariate analysis showed that differences in sexual activity (number of male sexual partners) and correlates of sexual activity (age and hepatitis B incidence) accounted for the differences in incidence of HIV-1 infection between the New York City and San Francisco cohorts. These covariates did not explain the lower incidence in the Amsterdam cohort. In conclusion, significant differences were found in the spread of HIV-1 in cohorts of homosexual men in Amsterdam, New York City, and San Francisco. These dissimilarities were probably due to a combination of differences in sexual activity at the time the epidemic began and a later introduction of HIV-1 in Amsterdam.

Cohort Studies↗
PubMed1993

A stochastic model of the HIV epidemic and the HIV infection distribution in a homosexual population.

In this paper we develop a stochastic model for the HIV epidemic in a homosexual population and use the model to characterize the HIV infection distribution and seroconversion distribution. Through computer-generated infection distributions and seroconversion distributions, we assess the effects of various risk factors on these distributions. The fitting of some data sets generated by computer suggests that the three-parameter generalized log-logistic distribution should be assumed as the infection distribution for the proposed stochastic model of HIV epidemics.

Disease Outbreaks↗
PubMed1993

Gender differences in reported AIDS-indicative diagnoses.

To compare AIDS-defining conditions in women and men, US adult AIDS cases diagnosed between January 1988 and June 1991 and reported to the Centers for Disease Control and Prevention through June 1992 were examined. For most AIDS-defining conditions, the prevalence was similar for women and men when differences in race/ethnicity and mode of transmission were accounted for. Pneumocystis carinii pneumonia was the most prevalent condition (> 50%) regardless of gender, race/ethnicity, or mode of transmission. By logistic regression analysis, among injection drug users, conditions reported significantly more frequently in women than in men include esophageal candidiasis (odds ratio [OR], 1.51; 95% confidence interval [CI], 1.40-1.62), herpes simplex virus (HSV) disease (OR, 1.68; CI, 1.46-1.94), and cytomegalovirus (CMV) disease (OR, 1.43; CI, 1.18-1.73). More knowledge of the interrelationships in women between HIV infection and secondary opportunistic infections, including candidiasis and sexually transmitted disease (e.g., HSV and CMV) is needed.

AIDS-Related Opportunistic Infections↗
PubMed1993

Organ-specific metastases in melanoma: experimental animal models.

Metastases from certain primary tumors frequently exhibit specific organ preference. Animal models have been developed to induce in a reproducible fashion the formation of organ-specific metastases by malignant melanoma cells. Some of these models rely on the use of immunodeficient mice, which can support the growth of murine as well as human malignant melanomas. Moreover, immunodeficient mice, because of their diminished ability to mount an effective immune response, allow the expression of malignant properties (e.g., preferential colonization of certain organs), which are intrinsic to transplanted melanoma cells. This review discusses the relevant factors (and limitations) of some of the animal models used to study the in vivo properties of melanoma cells.

Animals↗
PubMed1992

Projections of the number of persons diagnosed with AIDS and the number of immunosuppressed HIV-infected persons--United States, 1992-1994.

This report presents projections of the number of persons who will initially be diagnosed with a condition included in the 1987 surveillance definition for acquired immunodeficiency syndrome (AIDS) in the United States during the period 1992-1994. The report also presents estimates and projections of the prevalence of persons infected with the human immunodeficiency virus (HIV) who have CD4+ T-lymphocyte (T-cell) counts < 200/microL and who have not been diagnosed with a condition listed in the 1987 AIDS surveillance definition. These estimates and projections are used to predict the effect of expanding the AIDS surveillance definition to include all HIV-infected persons with a CD4+ T-cell count < 200/microL. Approximately 58,000 persons were diagnosed with AIDS in the United States during 1991. During the period 1992-1994, the number of persons newly diagnosed with AIDS is expected to increase by at most a few percent annually, with approximately 60,000-70,000 persons diagnosed per year. Although AIDS diagnoses among homosexual and bisexual men and among injecting drug users are projected to reach a plateau during this period, the number of AIDS diagnoses among persons whose HIV infection is attributed to heterosexual transmission of HIV is likely to continue to increase through 1994. The number of living persons who have been diagnosed with AIDS is expected to increase from approximately 90,000 in January 1992 to approximately 120,000 in January 1995. There is, however, considerable uncertainty in these projections. For example, the plausible range for the number of persons initially diagnosed with AIDS in 1994 is 43,000-93,000. CDC estimates that, as of January 1992, 115,000-170,000 U.S. residents had severe immunosuppression (a CD4+ T-cell count < 200 cells/microL without a diagnosis of AIDS in an HIV-infected person). Only about 50,000 of these persons were receiving medical care for HIV-related conditions and were known to have a CD4+ T-cell count < 200 cells/microL. The number of persons with severe immunosuppression is expected to increase to 130,000-205,000 by January 1995, with the actual number more likely to be in the lower half of this range than the upper half. The expanded AIDS surveillance definition, which includes severe immunosuppression, is predicted to result in an increase of approximately 75% in the number of persons reported during 1993, but an increase of < 20% in 1994 compared with the number of persons who would have been reported had the definition not been changed.(ABSTRACT TRUNCATED AT 400 WORDS)

Acquired Immunodeficiency Syndrome↗