On the global orbits in a bistable CML.

In an infinite one-dimensional coupled map lattice (CML) for which the local map is piecewise affine and bistable, we study the global orbits using a spatiotemporal coding introduced in a previous work. The set of all the fixed points is first considered. It is shown that, under some restrictions on the parameters, the latter is a Cantor set, and we introduce an order to study the fixed points' existence.

[AIDS; new developments. I. HIV tests: time for a more active policy].

Until recently, an HIV test was of limited importance for persons who had been at risk for HIV as effective drugs were not available. With the advent of a new generation of antiretroviral drugs with beneficial effect after early treatment, knowledge of the HIV serostatus has become of more importance to asymptomatic persons. There is no need for a mass screening campaign however, as there is no cure as yet.

Rapid disease progression in human immunodeficiency virus type 1-infected individuals with adverse reactions to trimethoprim-sulfamethoxazole prophylaxis.

We studied the relation between the occurrence of adverse reactions to trimethoprim-sulfamethoxazole (TMP-SMZ) prophylaxis and the subsequent course of human immunodeficiency virus (HIV) infection in a cohort of homosexual men. Adverse reactions to TMP-SMZ were associated with a more rapid progression to AIDS (P < .001) and death (P < .

Associations of age, immunosuppression, and AIDS among homosexual men in the Tricontinental Seroconverter Study.

To characterize the associations of age, immunosuppression, and AIDS outcomes, we evaluated serial measures of CD4+ lymphocytes from 376 homosexual men with documented dates of HIV-1 seroconversion registered in the Tricontinental Seroconverter Study. Using regression models and adjusting for variation within individuals, we found no association between age and the number of CD4+ lymphocytes at seroconversion or with CD4+ lymphocyte decline after seroconversion. Men who developed opportunistic infections had fewer CD4+ lymphocytes at the time of diagnosis compared with men who developed AIDS-defining Kaposi's sarcoma.

Estimating the size of the HIV epidemic among injecting drug users in Amsterdam.

Aim of this study was to assess the cumulative incidence of HIV-infection, AIDS and pre-AIDS death in the population of injecting drug users (IDU) in Amsterdam. By assuming equivalence, between a cohort of IDU and the IDU population, of the ratios of incidences of AIDS and pre-AIDS death to the number of HIV positive persons giving rise to these incidences, the numbers of HIV positive persons and pre-AIDS deaths in the population could be calculated, given that other parameters were known. Cohort study data on HIV prevalence and incidences of HIV infection, AIDS, and pre-AIDS death, were combined with national AIDS surveillance data.

Differentiation of respiratory epithelium: the effects of retinoic acid and carcinogens on the expression of mucociliary vs. squamous phenotype.

Changes in ultrastructural characteristics and mucin gene expression were examined in rat tracheal explants cultured in a synthetic medium +/- retinoic acid (RA), benzo[a]pyrene (B[a]P) and N-methyl-N-nitrosourea (NMNU). In the RA(+) cultures, no changes in either ultrastructural features or mucin gene expression were detected after 48 h incubation. After 96 h incubation, however, the ultrastructural features associated with the squamous phenotype were characteristics of cultures containing the two carcinogens and the mucin gene expression was slightly reduced.

Gag-specific immune responses after immunization with p17/p24:Ty virus-like particles in HIV type 1-seropositive individuals.

Gag-specific immune responses and changes in HIV-1 RNA levels were evaluated in eight HIV-1-infected persons, in order to assess the immunotherapeutic potential HIV-1 p17/p24: Ty virus-like particles (p24-VLP). All treated subjects showed transient and dose-dependent proliferative responses to the Ty-VLP carrier (stimulation index [SI], 2.0-119.

Summary of track C: epidemiology and public health.

Aim: To review Track C on epidemiology and public health.

Descriptive Epidemiology: Recent trends in the descriptive epidemiology are reported, for example, the rapid spread of HIV in certain Asian countries and the more precise insights in the spread thanks to subtyping of HIV-1 (and HIV-2).

Transmission: There is now ample evidence that sexually transmitted diseases enhance the rate of transmission.

T cell telomere length in HIV-1 infection: no evidence for increased CD4+ T cell turnover.

Progression to acquired immunodeficiency syndrome (AIDS) has been related to exhaustion of the regenerative capacity of the immune system resulting from high T cell turnover. Analysis of telomeric terminal restriction fragment (TRF) length, a marker for cellular replicative history, showed that CD8(+) T cell TRF length decreased but CD4(+) T cell TRF length was stable during the course of human immunodeficiency virus type-1 (HIV-1) infection, which was not explained by differential telomerase activity. This observation provides evidence that turnover in the course of HIV-1 infection can be increased considerably in CD8(+) T cells, but not in CD4(+) T cells.

[Results of screening for HIV antibodies in pregnant women in Amsterdam reference stations, 1988-1995].

In order to determine the prevalence of HIV in the general heterosexual population of Amsterdam, 16,709 pregnant women attending two hospitals and one maternity clinic in the period 1988-1995 were asked to undergo a HIV test, of whom 15,276 gave informed consent (91.4%). Pregnant women with a risk of HIV infection were possibly overrepresented in those who refused.

Differences in progression to AIDS between injection drug users and homosexual men with documented dates of seroconversion.

We compared rates of progression to AIDS for 99 injection drug users and 120 homosexual men with documented dates of HIV-1 seroconversion. The crude risk of developing AIDS was higher among homosexual men than injection drug users [relative hazard (RH) = 2.4; 95% confidence interval (CI) = 1.

Large declines in sexual risk behavior with noncommercial partners among heterosexual injection drug users in Amsterdam, 1989-1995.

Previous studies among injection drug users have reported small or nonexistent reductions in sexual risk behavior with noncommercial partners, and a large potential for further heterosexual spread of human immunodeficiency virus (HIV) is thought to be present. In the present study, a long-term follow-up and detailed data on sexual behavior were available. Trends were determined using data collected at 5,214 visits of 653 heterosexual injection drug users who participated in the Amsterdam Cohort Study in Amsterdam, the Netherlands between April 1989 and May 1995.

Immunization with recombinant p17/p24:Ty virus-like particles in human immunodeficiency virus-infected persons.

In studies of the natural history of human immunodeficiency virus type 1 (HIV-1) infection, it has been repeatedly shown that higher-titer antibody responses to the HIV gag p24 protein correlate with less rapid disease progression. In HIV-negative persons, immunization with HIV-1 p17/p24:Ty virus-like particles (p24-VLP) induced humoral and cellular immune responses to p24. This construct was therefore studied as a potential immunotherapeutic agent with the objective of augmenting the immune response to p24 in a double-blind placebo-controlled trial involving 74 p24 antibody-positive, asymptomatic HIV-1-infected subjects with CD4 cell counts > 350/mm3.

Human immunodeficiency virus infection and other risk factors for skin abscesses and endocarditis among injection drug users.

Objective: To study incidence rates of and risk factors for skin abscesses at the site of injection and episodes of endocarditis among injection drug users (IDU).

Design: A comprehensive, open cohort study of drug users on the natural history of human immunodeficiency virus (HIV) infection.

Methods: From 1986 to 1994, injection drug users in Amsterdam were included in the study.

Birth weight has increased over a generation.

The authors examined secular trends in birth weight for a geographically defined population over 40 years, controlling for migration effects. The study was an analysis first of all Illinois births between 1950 and 1990 and second of a subset of births for which two succeeding generations were born in the state. For the latter analysis, the authors created a transgenerational birth file by linking infant birth records to the birth records of their parents.

Low T cell reactivity to combined CD3 plus CD28 stimulation is predictive for progression to AIDS: correlation with decreased CD28 expression.

In 219 HIV-1-infected men of the Amsterdam cohort we measured CD4+ T cell numbers and in vitro T cell responses to CD3 MoAbs with or without CD28 costimulation and phytohaemagglutinin (PHA). The value of these markers was estimated for disease progression within 4 years. CD28 expression on T cells has been related to T cell responses.

[HIV incidence in a cohort of homosexual men and a cohort of injecting drug users in Amsterdam, 1985-1995].

Since 1984/1985 a cohort of homosexual men (HM; n = 770 initially HIV-seronegative) and one of injecting drug abusers (IDU; n = 675 initially seronegative) are being followed in Amsterdam, in order to assess the HIV epidemic in these high-risk groups. The HIV incidence in HM fell from 7.2/100 person years in 1985 to 1.

Evidence for HIV type 1 strains of U.S. intravenous drug users as founders of AIDS epidemic among intravenous drug users in northern Europe.

To establish an epidemiological link between HIV-1 epidemics in U.S. and European homosexual men and intravenous drug users (IVDUs) we analyzed the HIV-1 gp120 V3 sequences in both risk groups.

Differences in clinical manifestations of genital chlamydial infections related to serovars.

Objectives: To study the association of serovars of Chlamydia trachomatis with clinical manifestations of genital tract infection and socio-demographic characteristics.

Methods: In 1986-88 the C trachomatis isolates from 159 heterosexual men and 116 women attending a sexually transmitted disease (STD) clinic were collected and typed accordingly. A medical history was recorded, a physical examination took place and samples were taken for laboratory diagnostics.

The impact of drug users on inpatient hospital care during the human immunodeficiency virus epidemic in Amsterdam.

Background: As a consequence of the human immunodeficiency virus (HIV) epidemic, which continues among illicit drug users, high rates of HIV-associated morbidity are believed to exist. This study focuses on hospitalizations of drug users and on the relative contribution of drug users to the total burden of inpatient hospital care in Amsterdam.

Methods: During the years 1990-1992, data were collected on hospital admissions of injecting and non-injecting drug users to all 10 general and university hospitals in the city of Amsterdam (population 700 000; estimated number of drug users 5800).

Lack of consistency between five definitions of nonprogression in cohorts of HIV-infected seroconverters.

Objective: To identify appropriate criteria for characterizing HIV-infected nonprogressors.

Design: Five definitions were compared as follows: (1) last CD4 count > 500 x 10(6)/l; (2) two most recent CD4 counts > 500 x 10(6)/l; (3) calculated CD4 count based on linear regression > 500 x 10(6)/l; (4) CD4 slope > or = 0 with no antiretroviral use; (5) all CD4 counts > 500 x 10(6)/l, decline in CD4 slope < 5 cells per year, no antiretroviral use.

Participants: Five prospective cohorts of homosexual men with documented dates of HIV-1 seroconversion.

Use of immunological markers and continuous-time Markov models to estimate progression of HIV infection in homosexual men.

Objectives: We used continuous-time Markov models based on CD4 cell counts and anti-CD3 reactivity (i.e., measure for T-cell quality) to study the progression of HIV infection in a cohort study of homosexual men in Amsterdam.

Incidence and risk factors for pneumonia in HIV infected and non-infected drug users.

Objective: To study the incidence and risk factors for pneumonia in a cohort of HIV infected and non-infected drug users (DU).

Design: A prospective epidemiological study.

Setting And Patients: Injecting and non-injecting DU who attended the Municipal Health Service in Amsterdam for follow-up visits in the study.