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Biomedical subjects

A Tobias

Publications and source records attributed to A Tobias.

30 records · Page 2Linked to original sources
PubMed1996

A simplified procedure for studies of intestinal immunity in rabbits.

As interest in the development of oral vaccines continues to rise, alternative animal models for studies of mucosal immunity are needed. The present study examines a simplified procedure for delivering antigen to rabbit Peyer's patches via an indwelling cannula. The cannula was placed 3-4 cm proximal to the Peyer's patch, and was used to deliver four weekly doses of the potent mucosal immunogen, cholera toxin (CT). Anti-CT specific fecal secretory IgA (S-IgA), serum IgG and serum IgA were found in essentially equal amounts in rabbits with cannulas and in rabbits fitted with Thiry-Vella (T-V) isolated ileal loops. In contrast to animals with T-V loops, the intestinal flora of animals with cannulas contained less bacterial overgrowth with Pseudomonas sp. Further, the villus architecture remained histologically normal in appearance and there were fewer post-surgical complications associated with this technique than with T-V loops. This simplified technique should allow wider use of rabbits in studies of mucosal immunity.

Animals↗
PubMed1996

Short term effects of air pollution on health: a European approach using epidemiologic time series data: the APHEA protocol.

BACKGROUND AND OBJECTIVES: Results from several studies over the past five years have shown that the current levels of pollutants in Europe and North America have adverse short term effects on health. The APHEA project aims to quantifying these in Europe, using standardised methodology. The project protocol and analytical methodology are presented here. DESIGN: Daily time series data were gathered for several air pollutants (sulphur dioxide; particulate matter, measured as total particles or as the particle fraction with an aerodynamic diameter smaller than a certain cut off, or as black smoke; nitrogen dioxide; and ozone) and health outcomes (the total and cause specific number of deaths and emergency hospital admissions). The data included fulfilled the quality criteria set by the APHEA protocol. SETTING: Fifteen European cities from 10 different countries with a total population over 25 million. METHODOLOGY: The APHEA collaborative group decided on a specific methodological procedure to control for confounding effects and evaluate the hypothesis. At the same time there was sufficient flexibility to allow local characteristics to be taken into account. The procedure included modelling of all potential confounding factors (that is, seasonal and long term patterns, meteorological factors, day of the week, holidays, and other unusual events), choosing the "best" air pollution models, and applying diagnostic tools to check the adequacy of the models. The final analysis used autoregressive Poisson models allowing for overdispersion. Effects were reported as relative risks contrasting defined increases in the corresponding pollutant levels. Each participating group applied the analyses to their own data. CONCLUSIONS: This methodology enabled results from many different European settings to be considered collectively. It represented the best available compromise between feasibility, comparability, and local adaptibility when using aggregated time series data not originally collected for the purpose of epidemiological studies.

Air Pollutants↗
PubMed1996

Air pollution and mortality in Barcelona.

STUDY OBJECTIVES: Studies conducted in Barcelona reported a short term relation between daily air pollutant values and emergency department admissions for exacerbation of chronic obstructive pulmonary diseases and asthma. Air pollution in Barcelona is mainly generated by vehicle exhaust and is below the World Health Organization air quality guidelines. The acute relation between air pollution and mortality was assessed. DESIGN: Daily variations in total mortality, mortality in subjects older than 70 years, and cardiovascular and respiratory mortality were related with daily variations in air pollutants for the period 1985-91, using autoregressive Poisson regression models that allow to control for temperature, relative humidity and variables handling temporal and autoregressive patterns. MAIN RESULTS: Black smoke and sulphur dioxide (SO2) were related to total mortality (relative risks (RR) for 100 micrograms/m3 = 1.07 and 1.13 respectively), elderly mortality (RR = 1.06 and 1.13), cardiovascular mortality (RR = 1.09 and 1.14), and respiratory mortality (RR = 1.10 and 1.13); all the associations being statistically significant, except for respiratory mortality (p = 0.07). The association between SO2 and respiratory mortality was stronger in summer (1.24, p < 0.01) than in winter (1.08, p > 0.1). Oxidant pollutants (nitrogen dioxide and ozone) were positively related with elderly mortality (RR = 1.05 and 1.09, respectively) and cardiovascular mortality (RR = 1.07 and 1.09) during the summer (p < 0.05), but not during the winter. CONCLUSIONS: Current air pollutant levels were related to mortality in Barcelona. These results were consistent with similar studies in other cities and coherent with previous studies with emergency room admissions in Barcelona.

Age Factors↗
PubMed1996

The risk of asthma attributable to occupational exposures. A population-based study in Spain. Spanish Group of the European Asthma Study.

The prevalence of occupational asthma has usually been estimated from registers of cases rather than population surveys. We examined the causes and derived estimates of the risk of asthma attributable to occupational exposures in a randomly selected population of five areas of Spain. The study is part of the EC Respiratory Health Survey and comprises 2,646 subjects age 20 to 44 yr. Bronchial reactivity was determined in 1,797 subjects and atopy in 2,164. Twenty-one occupational sets were defined using information on current occupation, or in subjects reporting change of occupation due to respiratory problems, their occupation at that time. The highest risk of asthma was observed for laboratory technicians, spray painters, bakers, plastics and rubber workers, welders, and cleaners. The risk of asthma attributed to occupational exposures after adjusting for age, sex, residence, and smoking status was 5.0% when asthma was defined as "bronchial reactivity and a report of wheezing or whistling in the chest during the last 12 mo," and 6.7% when asthma was defined as "bronchial reactivity and a report of asthma-related symptoms or medication." Estimates of the attributable risk for adult onset asthma were higher. Occupational exposures constitute a substantial cause of asthma in the young adult Spanish population.

Adult↗
PubMed1992

Relationship between nutritional status indicators and length of hospital stay for patients with diverticular disease.

The length of a patient's stay in a hospital is an indication of the patient's recovery rate. Length of hospital stay has also become an important economic factor for hospitals. This is especially true since 1983 as a result of implementation of the Prospective Payment System based on diagnosis-related groups. In this study, the results of routine laboratory tests of nutritional status were examined for relationships between nutritional status and the length of hospital stay. We conducted a retrospective analysis of 163 patients with diverticulosis and diverticulitis of the colon to determine which nutrition assessment parameters are sensitive in predicting recovery rate (length of hospital stay). We found that serum albumin level was negatively correlated with length of hospital stay. Women without gastrointestinal bleeding stayed an average of 20.1 +/- 8.5 days when serum albumin level was 30 g/L or less vs 11.2 +/- 10.5 days when it was greater than 30 g/L. Hemoglobin and/or hematocrit levels were also negatively correlated with length of hospital stay for this group. Women without bleeding stayed an average of 16.4 +/- 13.4 days when the hemoglobin level was 120 g/L or less vs 10.4 +/- 9.1 days when it was greater than 120 g/L. These results suggest that a patient's nutritional status upon admission has an effect on the length of hospital stay for patients with diverticular disease.

Diverticulitis, Colonic↗
PubMedDate not supplied

Short-term effects of air pollution on hospital admissions of respiratory diseases in Europe: a quantitative summary of APHEA study results. Air Pollution and Health: a European Approach.

The Air Pollution and Health: a European Approach (APHEA) project is a coordinated study of the short-term effects of air pollution on mortality and hospital admissions. Five West European cities (i.e., London, Amsterdam, Rotterdam, Paris, Milano) contributed several years of hospital admissions data for all respiratory causes. In the current study, the authors describe the results obtained from the quantitative pooling (meta-analysis) of local analyses. The diagnostic group was defined by ICD 460-519. The age groups studied were 15-64 y (i.e., adults) and 65+ y (elderly). The air pollutants studied were sulfur dioxide; particles (i.e., Black Smoke or total suspended particles); ozone; and nitrogen dioxide. The pollutants were obtained from existing fixed-site monitors in a standardized manner. We used Poisson models and standardized confounder models to examine the associations between daily hospital admissions and air pollution. We conducted quantitative pooling by calculating the weighted means of local regression coefficients. We used a fixed-effects model when no heterogeneity could be detected; otherwise, we used a random-effects model. When possible, the authors investigated the factors correlated with heterogeneity. The most consistent and strong finding was a significant increase of daily admissions for respiratory diseases (adults and elderly) with elevated levels of ozone. This finding was stronger in the elderly, had a rather immediate effect (same or next day), and was homogeneous over cities. The elderly were affected more during the warm season. The Sulfur dioxide daily mean was available in all cities, and it was not associated consistently with an adverse effect. Effects were present in areas in which more than one station was used in the assessment of daily exposure. Some significant associations were observed, although no conclusion that related to an overall particle effect could be drawn. The effect of Black Smoke was significantly stronger with high nitrogen dioxide levels on the same day, but nitrogen dioxide itself was not associated with admissions. The ozone results were in good agreement with the results of similar U.S. studies. The coherence of the results of this study and other results gained under different conditions strengthens the argument for causality.

Adolescent↗
PubMedDate not supplied

[Time series methods in epidemiological studies on air pollution].

The time series methods in the epidemiological studies on air pollution are reviewed, illustrated by means of an autoregressive Poisson regression which was employed in the APHEA and EMECAM Projects. A listing is provided of the variations in the daily number of deaths of people over age 70 (all causes, CIE-9:001-799) in Barcelona, 1991-1995, with the average variations in the daily smog pollution levels. A Poisson regression is used insofar as the dependent random variable presumably follows such a probability distribution. As variable possibly leading to confusion, the impact of weather variables (daily temperature and relative humidity averages), seasonal, tendency-related behaviours and day of the year on the death rate are taken into account (all estimated on a determinist basis), in addition to any other variable which behaves in a way that it can be related to the dependent variable (i.e. flu epidemics). The relationship between the death rate and the confusing-causing variables is modelled on a non-linear basis, and the foreseeable lag times are also taken into account (i.e. by using explicative variable time lags). However, due to control not being perfect, it has been decided to opt for estimating an autoregressive Poisson model (adding in some different explicative variables time giving rise to a lag in the death rate) offsetting the residual autocorrelation. The main advantage of the method of analysis described above is that of making it possible to control confusing variables from a determinist standpoint with a software to which all of the groups taking part in this Project had access. This also affords the possibility of using this method in a set, standardized manner, facilitating the comparison of results and making an objective point analysis possible.

Age Factors↗
PubMedDate not supplied

[The short-term effects of air pollution on mortality. The results of the EMECAM project in the city of Barcelona, 1991-1995. Estudio Multicéntrico Español sobre la Relación entre la Contaminación Atmosférica y la Mortalidad].

BACKGROUND: Most of the studies which demonstrate the existence of a short-term relationship between air pollution and morbidity and the Mortality analyze the impact of "classic" pollutants which are by-products of combustion. However, the changes in the sources of these emissions, shifting basically toward road traffic, has made a change in air pollution, heightening the importance of the photochemical components, such as ozone (O3) and nitrogen dioxide (NO2). Barcelona is a city located in a mild climate zone, and its air pollution comes mainly from vehicle emissions. The main objective of this article is that of analyzing the relationship between the photochemical pollutants, NO2 and O3 and the death rate for different causes in the city of Barcelona throughout the 1991-1995 period, using the procedure for analysis set out as part of the EMECAM Project. METHODS: Daily changes in the number of deaths resulting from all causes, of the number of deaths for all causes of those over age 70, of the number of deaths resulting from cardiovascular diseases, and of the number of deaths resulting from respiratory-related causes are related to the daily changes in the photochemical pollutants using autoregressive Poisson models, controlling confusion-causing variables such as the temperature, the relative humidity, the systematic time structure and the autoregressive structure. RESULTS: Except for the relationship between O3 and the mortality for causes involving respiratory diseases, the relationships between photochemical pollutants and the mortality for all the causes considered were statistically significant. The risks related to dying as a result of rises in O3 were greater than as a result of rises in NO2, almost triple among cardiovascular diseases. The risks related to dying for all the causes are lower than for specific causes and than for those individuals over age 70. The results of the analysis by six-month periods are quite similar to the overall results, revealing, in any event, relative risks somewhat greater during the warm months (May to October). CONCLUSIONS: Photochemical pollution, especially that which is caused by O3, comprises a health risk. In the case of NO2, this might not be more than an indicators of the suspended particles or of other pollutants stemming from city traffic. There may be a certain adjustment between six-month periods of the impact of O3 on the mortality for causes of the circulatory system.

Age Factors↗