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Biomedical subjects

A Muñoz

Publications and source records attributed to A Muñoz.

At least 397 records · Page 22Linked to original sources
PubMed1992

Analysis of islet cell antibodies reactivity to a human islet cell line.

A human pancreatic beta cell line (HP62) was tested for reactivity with islet cell antibodies (ICA) as compared with previously-established methods. Using indirect immunofluorescence test, we found that HP62 cell line failed to react in a specific way with ICA from type 1 (insulin-dependent) diabetic patients since sera from normal controls showed a reactivity similar to that found in the patients. So, the usefulness of this human beta cell line as a tool of immunological purpose is questioned when indirect immunofluorescence procedures are used.

Autoantibodies↗
PubMed1992

Estimating familial aggregation while adjusting for covariates. Application to pulmonary function data from black and white sibships.

Although crude correlations are useful in family studies, some adjustment for effects of risk factors that vary both within and among families if often needed. A linear model for estimating sibship correlations while simultaneously considering height, age, race, sex, ascertainment, and smoking status was used on pulmonary function data on 1-second forced expiratory volume (FEV1) and the natural logarithm of the ratio of FEV1 to forced vital capacity (lnFEV%) from 402 adults in 152 white sibships and 172 adults in 59 black sibships. Crude correlations of .271 +/- .048 (FEV1) and .342 +/- .047 (lnFEV%) decreased significantly to .206 +/- .048 and .231 +/- .048, respectively, after adjustment. For black and white sibs, adjusted intraclass correlations, although not statistically different, were .153 +/- .089 and .225 +/- .055 (FEV1), respectively, and were .103 +/- .088 and .275 +/- .054 (lnFEV%), respectively, suggesting that pulmonary function may aggregate more strongly among whites. This analysis illustrates how risk factor adjustment can be readily incorporated into familial correlation studies.

Adult↗
PubMed1992

Seroprevalence and cofactors of HTLV-I infection in Tumaco, Colombia.

This study presents an analysis of the factors associated with HTLV-I seroprevalence in the endemic area of Tumaco, Colombia. During June to August 1988, 1,077 individuals were selected at random from a population of 45,594. The overall prevalence rate of HTLV-I antibodies was 2.8%. Among females prevalence was significantly higher (p less than 0.02) than among males. Rates increased substantially with age. HTLV-I prevalence among individuals with history of use of intravenous medications was significantly higher (p less than 0.001) than in those without such history. Logistic regression analysis included age in years, indicators for male gender, and for i.v. injections, and their interactions. Age was very strongly associated to HTLV-I infection among females. At early ages prevalence was not different between sexes, but females presented a significantly higher rate than males after age 42. History of i.v. administered medications was very strongly associated in the univariate analysis and, although significance was borderline in the multivariate analysis, it had the effect of doubling the odds of HTLV-I infection.

Adolescent↗
PubMed1992

Immune serum markers and CD4 cell counts in HIV-infected intravenous drug users.

We examined the association of three serum immune markers with CD4 cell counts in a large cohort of i.v. drug users with and without human immunodeficiency virus (HIV) infection. Levels of beta 2-microglobulin and neopterin were significantly elevated in HIV-infected subjects and increased in association with decline in CD4 cell counts (all p less than 0.001). Serum IgA levels in HIV-seropositive individuals were significantly elevated only when the CD4 cell count was less than 200/microliters (p less than 0.001). After controlling for HIV status and CD4 count, recent history of hepatitis was associated with significantly higher beta 2-microglobulin (p = 0.028) and marginally higher neopterin (p = 0.052) levels. There was no association of race, gender, or drug use patterns with levels of serum immune markers after controlling for HIV status and CD4 count. These data indicate that immune activation is coupled with immunosuppression in HIV-infected i.v. drug users. In addition, beta 2-microglobulin and neopterin levels are elevated in persons with a recent history of hepatitis but not in those with recent non-AIDS-defining bacterial infections. Markers of immune activation do not vary by race, gender, or drug use patterns among i.v. drug users.

Biomarkers↗
PubMed1992

Effect of CD4+ cell count measurement variability on staging HIV-1 infection.

A single CD4+ cell count (CD4) measurement is often used to stage HIV-1 infection, decide when to initiate prophylactic therapy and inform patients, and may soon even define AIDS onset. Documentation of the reliability and validity of employing CD4 for the above purposes in a population-based setting is needed. We utilized data from 4,954 homosexual/bisexual men followed over 6 years, with CD4 testing at 6 month intervals, to study the timing of CD4-based staging of HIV-1 disease and quantify and evaluate the potential impact of CD4 measurement error. The median time from seroconversion to first CD4 test below 500 x 10(6)/L or clinical AIDS was 1.70 years, and the first CD4 test below 200 x 10(6)/L or clinical AIDs was 5.29 years. The time from first testing less than 500 x 10(6)/L to clinical AIDS in untreated men was 5.55 years. With confirmatory retesting, these times were significantly lengthened. The 95% confidence ranges for the true CD4 state in individuals with measured CD4 of 500 and 200 x 10(6)/L are at least (297 x 10(6), 841 x 10(6)/L) and (118 x 10(6), 337 x 10(6)/L), respectively. Without confirmatory retesting, individuals with true CD4 remaining at 700 x 10(6) and 280 x 10(6)/L have at least a 40% chance for one of five CD4 measurements to fall below guideline limits of 500 x 10(6) and 200 x 10(6)/L, respectively. Confirmatory retesting can reduce these probabilities to as low as 4%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Influence of HIV-1 infection and cigarette smoking on leukocyte profiles in homosexual men. The Multicenter AIDS Cohort Study.

The interaction between the effects of HIV-1 infection and cigarette smoking on leukocyte profiles was studied in 307 HIV-1 seroconverters in the Multicenter AIDS Cohort Study (MACS). Longitudinal data for white blood cell (WBC) counts, WBC differentials, T cell subsets, and smoking behavior were collected semiannually for up to 7 years. Prior to seroconversion, total WBC count increased in direct proportion to daily cigarette consumption, but this effect disappeared within 3 years of seroconversion. Analyses of WBC subsets (lymphocytes, monocytes, and granulocytes) and lymphocyte subsets (CD4+, CD8+ and non-T[CD3-]) showed that smoking had only minor effects on the proportions of these cells. In contrast, HIV-1 seroconversion was associated with a dramatic decrease in CD4+ lymphocyte percentage, a large increase in CD8+ lymphocyte percentage, a small increase in total lymphocyte percentage, and small decreases in the non-T lymphocyte and granulocyte percentages. These findings indicate that the effect of smoking on CD4 cell counts is (a) nonspecific, (b) maximal in seronegative individuals; and (c) lost by 3 years after seroconversion. Although the mechanism of the loss of smoking-induced leukocytosis after seroconversion remains to be determined, our results suggest that the effects of smoking are not likely to be important in the clinical use of leukocyte measurements, including measurements of CD4 lymphocytes, in individuals who have been HIV-1 seropositive for more than 3 years.

CD4-CD8 Ratio↗
PubMed1992

A parametric family of correlation structures for the analysis of longitudinal data.

In epidemiological settings, we are often faced with numerous short time series, and a parsimonious parametrization of the correlation structure is desired in order to optimize the efficiency of the estimation procedure. We propose a damped exponential correlation structure for modeling multivariate Gaussian outcomes. The correlation between two observations separated by s units of time is modeled as gamma s theta, where gamma is the correlation between elements separated by one s-unit, and theta is a damping parameter. For (theta = 0), (theta = 1), and theta----infinity), the correlation structures of compound symmetry, first-order autoregressive, and first-order moving average processes are obtained. Although the AR(2) dependency structure, and the combination of random effects and AR(1) errors are not special cases of the proposed parametric family, these structures can be well approximated within the family for short time series. Maximum likelihood methods for parameter estimation and interpretations of intermediate models (0 less than theta less than 1) are discussed in the context of modeling pulmonary function in an adult population in The Netherlands and T-cell subsets in homosexual men infected with human immunodeficiency virus Type I.

Adult↗
PubMed1992

Cytoarchitecture and ultrastructural characteristics of the area octavolateralis of the urodele amphibian Pleurodeles waltlii.

The cytoarchitecture of the area octavolateralis (AOL) in Pleurodeles waltlii is studied by means of normal stained material. In addition, the main ultrastructural features of the cells in the AOL are described. In the AOL, three columns, one upon the other (dorsal, intermediate and ventral), are present. Each one includes a medially located cell group and lateral neuropil. While rostrally the three are well represented, the dorsal subdivision do not reach the same caudal extent where the intermediate column forms a small lobe. The ultrastructure of the neurons in the AOL reveals similarities with other cell types in the amphibian brain. A comparative analysis of the ultrastructure of vestibular cells with other vertebrates is also discussed.

Animals↗
PubMed1992

Acquired immune deficiency syndrome occurring within 5 years of infection with human immunodeficiency virus type-1: the Multicenter AIDS Cohort Study.

The objective of this study is to describe participants in the Multicenter AIDS Cohort Study (MACS) with incident infection due to the human immunodeficiency virus type-1 (HIV-1) in whom AIDS developed by March 1990 and within 5 years of seroconversion (group A). Secondly, behavioral, clinical, and immunologic characteristics of these men are compared to those of matched seroconverters remaining AIDS free (group B). Between entry into the MACS (April 1984-March 1985) and July 1989, 345 seronegative homosexual/bisexual men had HIV-1 antibody; of these men, AIDS developed in 32 by March 1990. The Kaplan-Meier estimates of the proportion of men with incident HIV-1 infection with AIDS were 6 months, 0%; 12 months, 1%; 24 months, 3%; and 48 months, 10%. These 32 men engaged in receptive anal intercourse with more partners before (p less than 0.005) and after seroconversion (p less than 0.005) and reported more sexually transmitted disease preseroconversion (p = 0.05) than did group B. These findings suggest that sexually transmitted co-factors, preseroconversion and/or postseroconversion, play a role in the progression of HIV-1 infection. Alternatively, greater sexual activity could increase the hazard of exposure to a more virulent HIV-1 strain.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Prognostic indicators for development of AIDS among intravenous drug users.

A cohort of 544 human immunodeficiency virus-1 (HIV-1) seropositive intravenous drug users (IVDUs) was recruited in 1988 and early 1989; data on laboratory markers, clinical symptoms, intravenous drug use, and demographics were collected. Forty-one IVDUs developed AIDS within 2 years of enrollment. Data were analyzed using methods of survival analysis. None of the individuals reported use of antiviral agents or Pneumocystis carinii prophylaxis at baseline. A very strong (p less than 0.001) dose-response relationship was identified between CD4 cell count at baseline and the subsequent development of AIDS. In multivariate analysis, both the presence of more than one clinical HIV-1-related symptom and serum neopterin greater than 12 nmol/L showed significant associations with the relative hazard (95% confidence interval) of AIDS after controlling for CD4 of 2.9 (1.6, 5.6) and 2.0 (1.0, 3.7), respectively. In these IVDUs, serum beta 2-microglobulin did not add predictive power for progression to AIDS. The effect of clinical symptoms was stronger for high CD4 cell counts, indicating the need to monitor HIV seropositive IVDUs with both laboratory studies and clinical evaluation.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[The effect of two lubricants (magnesium stearate and pruv) in the formation of tablets of four anti-ulcer agents/ by means of direct compression].

In this research we study the influence of two lubricants-Magnesium Stearate and Pruv--on the tablets elaboration of Cimetidine, Ranitidine, Famotidine and Pirenzepine by direct compression. The presence of 0.5% of lubricants improved the flow of all the formulations, but especially the Famotidine's formulation. The formulations with Magnesium Stearate had the worst results in tests of friability and tensile strength. All tablets with drugs and Pruv had high data in indentation hardness. The tablets of Cimetidine, Famotidine and Pirenzepine with Magnesium Stearate had less time of disintegration.

Anti-Ulcer Agents↗
PubMed1991

Estimating the 1978-1990 and future spread of human immunodeficiency virus type 1 in subgroups of homosexual men.

The authors studied the historical spread of human immunodeficiency virus type 1 (HIV-1) infection in homosexual/bisexual men and projected its future spread in these men using data from an AIDS-free cohort recruited during late 1984 in Baltimore, Maryland; Chicago, Illinois; Los Angeles, California; and Pittsburgh, Pennsylvania. Dates of preentry seroconversion in HIV-1 seroprevalent men were estimated using study entry values of hematologic variables influenced by HIV-1 infection. The authors used survival methods incorporating truncation to determine numbers/dates of seroconversion for men with a pre-1984 AIDS diagnosis who were selectively excluded by design from the 1984 AIDS-free cohort. Overall, the annual seroconversion hazard rose progressively from 0.4% in 1978 to 13.8% in 1983, dropped to 4.6% in 1985, and remained relatively stable at 1.1-2.2% from 1986 to 1990. By January 1990, almost 46% of men who were seronegative in 1978 had seroconverted. The authors estimated historical rates of spread by city, age, education, and ethnicity to examine the effects of these factors in the early and continuing stages of the HIV-1 epidemic. There were striking differences among cities with respect to pre-1985 seroconversion rates but not with respect to post-1985 seroconversion rates. Age, education, and ethnicity were all associated with 1978-1990 seroconversion rates. Future seroconversion among homosexual men was predicted assuming that the "stabilized" 1986-1990 hazards (stratified by age) observed here will be representative of future rates. Truncated Kaplan-Meier methods gave the probability of a seronegative 20-year-old man's remaining seronegative in subsequent years. Such a man has a 20.2% chance of seroconverting before reaching the age of 25 years (a 4.4% yearly hazard). The annual hazard drops to 2.5% between 25 and 30 years, to about 1.5% between 30 and 45 years, and to 1.0% between 45 and 55 years. The overall probability of seroconversion prior to age 55 years is about 50%, with seroconversion still continuing at and after age 55. Given that this cohort consists of volunteers receiving extensive anti-HIV-1 transmission education, the future seroconversion rates of the general homosexual population may be even higher than those observed here.

Adult↗
PubMed1991

Antibody to hepatitis C virus among cardiac surgery patients, homosexual men, and intravenous drug users in Baltimore, Maryland.

In order to define the risk factors for infection with hepatitis C virus, the authors determined the prevalence and incidence of antibodies to hepatitis C in three cohorts in Baltimore, Maryland, enrolled in prospective studies of human immunodeficiency virus (HIV-1) infection. Among 500 multi-transfused patients who underwent cardiac surgery in 1985 and 1986, 12 (2.4%) were hepatitis C seropositive before surgery while 19 (3.9%) developed antibodies in the 8-12 months after surgery. The seroprevalence of hepatitis C virus among 225 intravenous drug users followed since 1988 was 85%, which did not vary by HIV-1 status. Longer duration of intravenous drug use was significantly associated with hepatitis C seropositivity. Among 926 homosexual/bisexual men followed since 1984, 15 (1.6%) were hepatitis C seropositive; only intravenous drug use and a history of hepatitis A were marginally associated with hepatitis C in this population. No association was found between hepatitis C virus and HIV-1 or sexual behavior variables in this population. These data suggest that hepatitis C is readily transmitted by blood exposure, but is transmitted inefficiently by sexual means.

Adult↗
PubMed1991

Temporal trends in human immunodeficiency virus type 1 seroconversion 1984-1989. A report from the Multicenter AIDS Cohort Study (MACS).

The 5-year temporal trends in human immunodeficiency virus type 1 (HIV-1) seroconversion between 1984 and 1989 among homosexual/bisexual men participating in the Multicenter AIDS Cohort Study (MACS) are reported. Of 3,262 initially seronegative men, 368 (11.3%) had seroconverted by December 31, 1989. Although the incidence of seroconversion declined precipitously during the first 3 years of follow-up (from 4.1% to 0.9% per 6 months), no evidence for a further substantial reduction was noted after mid-1987, since 6-month incidence rates ranged between 0.5% and 1.2%. The Chicago cohort experienced an increase in HIV-1 seroconversion during both semesters of 1989; 2.1% and 1.6% per 6 months, respectively, became newly infected. Other MACS centers did not report such an increase. Center-specific differences were observed by race; black men were at higher seroconversion risk than white men in Baltimore/Washington (relative risk (RR) = 3.4) and Chicago (RR = 2.4), while Hispanic men were at higher risk than white men in Chicago (RR = 3.3). Younger age (less than 35 years) was also associated with HIV-1 seroconversion (RR = 1.5). It is disturbing to report an overall annual seroconversion rate of 1.2% for the 2 years prior to December 31, 1989, as well as evidence for a sustained recent increase in Chicago during 1989. Long-term maintenance of safe-sex behaviors should be the cornerstone of acquired immunodeficiency syndrome prevention among homosexual/bisexual men.

Age Factors↗
PubMed1991

Prevalence of antibody to HIV-1 among entrants to US correctional facilities.

Prevalence of antibody to the human immunodeficiency virus type 1 (HIV-1) was assessed among 10,994 consecutive male and female entrants to 10 correctional systems in the United States. The HIV-1 seroprevalence for the 10 systems ranged from 2.1% to 7.6% for men and 2.5% to 14.7% for women; seroprevalence among women was higher than among men across nine of 10 systems. Using age 25 years to divide the population, HIV-1 prevalence among young women (5.2%) was significantly higher than among young men (2.3%), but similar to that in both older women (5.3%) and older men (5.6%). Overall, HIV-1 rates for nonwhites (4.8%) were higher than those for whites (2.5%). Although categories were identified across correctional systems, which may serve to focus prevention programs, variability in rates among correctional systems indicates that program planning must take local conditions into consideration.

Acquired Immunodeficiency Syndrome↗