Short course training in epidemiology and biostatistics for graduate and undergraduate public health professionals.

The University of South Florida has developed short courses of 2 to 3 days in epidemiology and biostatistics geared to public health workers. A key focus is providing skills which will assist local and State public health units to assess their status and measure progress with respect to achieving their explicitly stated health objectives for the year 2000. The courses were developed after the identification of the training needs in health departments and other public health settings. The training objectives were (a) to enhance the biostatistics skills of professionals involved in the analysis of health data; (b) to reinforce basic knowledge of epidemiologic methods and its practical applications in public health settings, including measures of disease frequency and association, epidemic outbreak investigations, and the identification and use of surveillance data; and (c) to demonstrate the application of the risk factor approach to select the interventions needed to reach health objectives for year 2000 and how to evaluate such interventions. A total of 43 students have taken this course series. Professional staff in health departments cannot always enroll in formal training in epidemiology and biostatistics because of time limitations or a lack of a bachelor''s degree. However, the need exists. An alternative to such training could be the short course program described in this paper.     

Craniofacial Development: Neural Crest in Molecular Embryology

Craniofacial development, one of the most complex sequences of developmental events in embryology, features a uniquely transient, pluripotent stem cell-like population known as the neural crest (NC). Neural crest cells (NCCs) originate from the dorsal aspect of the neural tube and migrate along pre-determined routes into the developing branchial arches and frontonasal plate. The exceptional rates of proliferation and migration of NCCs enable their diverse contribution to a wide variety of craniofacial structures. Subsequent differentiation of these cells gives rise to cartilage, bones, and a number of mesenchymally-derived tissues. Deficiencies in any stage of differentiation can result in facial clefts and abnormalities associated with craniofacial syndromes. A small number of conserved signaling pathways are involved in controlling NC differentiation and craniofacial development. They are used in a reiterated fashion to help define precise temporospatial cell and tissue formation. Although many aspects of their cellular and molecular control have yet to be described, it is clear that together they form intricately integrated signaling networks required for spatial orientation and developmental stability and plasticity, which are hallmarks of craniofacial development. Mutations that affect the functions of these signaling pathways are often directly or indirectly identified in congenital syndromes. Clinical applications of NC-derived mesenchymal stem/progenitor cells, persistent into adulthood, hold great promise for tissue repair and regeneration. Realization of NCC potential for regenerative therapies motivates understanding of the intricacies of cell communication and differentiation that underlie the complexities of NC-derived tissues.     

Gender and Ethnic Differences in Survival in a Cohort of HIV Positive Clients

Objectives: The purpose of this study was to examine gender and ethnic differences in survival of persons receiving treatment for HIV infection to determine if differences existed, and if they did, to assess the possibility of explaining these differences by examining other factors, such as age, disease severity when beginning treatment, alcohol, illicit drugs, tobacco, educational level, living arrangements, antiretroviral treatment, PCP prophylaxis, sexually transmitted diseases, mode of transmission and opportunistic infections.

Design: A retrospective cohort study of all clients receiving treatment at an HIV only clinic from its opening in early 1988 until the end of May 1993. Statistical methods used to examine the data included incidence density ratios, Kaplan‐Meier survival curves, Breslow (generalized Wilcoxon) tests of equality of survival curves and Cox proportional hazards models both with and without time dependent covariates.

Results: In the cohort (37% African American, 7% Hispanic American and 25% female), 220 deaths occurred during 1223 person years of follow‐up. Compared to European American males, the following incidence density ratios were observed: European American females: 0.50, Hispanic American females: 0.70, Hispanic American males: 0.96, African American females: 1.28 and African American males: 2.38. The differences were noted above for gender/ethnicity groups were significant at the p < 0.0001 level. After adjusting for disease stage (as measured by laboratory testing of CD4 positive T‐lymphocytes), educational level, and age, no differences in survival by gender or ethnicity remained. Disease stage and educational level had the greatest prognostic significance.

Conclusions: European Americans entered treatment at a much earlier disease stage (as measured by CD4 positive T‐lymphocyte counts) and had higher educational levels (a surrogate for socioeconomic status) than African Americans. These factors may explain the longer survival in European Americans as compared to African Americans in this cohort.     

Mechanical stretch induces myelin protein loss in oligodendrocytes by activating Erk1/2 in a calcium-dependent manner

Myelin loss in the brain is a common occurrence in traumatic brain injury (TBI) that results from impact-induced acceleration forces to the head. Fast and abrupt head motions, either resulting from violent blows and/or jolts, cause rapid stretching of the brain tissue, and the long axons within the white matter tracts are especially vulnerable to such mechanical strain. Recent studies have shown that mechanotransduction plays an important role in regulating oligodendrocyte progenitors cell differentiation into oligodendrocytes. However, little is known about the impact of mechanical strain on mature oligodendrocytes and the stability of their associated myelin sheaths. We used an in vitro cellular stretch device to address these questions, as well as characterize a mechanotransduction mechanism that mediates oligodendrocyte responses. Mechanical stretch caused a transient and reversible myelin protein loss in oligodendrocytes. Cell death was not observed. Myelin protein loss was accompanied by an increase in intracellular Ca²⁺ and Erk1/2 activation. Chelating Ca²⁺ or inhibiting Erk1/2 activation was sufficient to block the stretch-induced loss of myelin protein. Further biochemical analyses revealed that the stretch-induced myelin protein loss was mediated by the release of Ca²⁺ from the endoplasmic reticulum (ER) and subsequent Ca²⁺-dependent activation of Erk1/2. Altogether, our findings characterize an Erk1/2-dependent mechanotransduction mechanism in mature oligodendrocytes that de-stabilizes the myelination program.     

Age,gender and seasonal patterns of asthma in emergency departments of southern Puerto Rico

We report findings derived from 55,547 emergency department records of asthmatic patients in the city of Ponce, Puerto Rico over a period of six years. The analysis of the data revealed that mean age of the asthmatic cases were 18.7 +/- 17.8 years, with 45% percent of the patients in the 1-9 years age range, and proportionally decreasing with age. In children 1-9 years the percent of males was 1.5 times that of females, and in 10-19 year-old group, admissions to the emergency room for males and females was identical, and between 20-69 years of age, the female ratio ranged from 1.5-2.12. The data also demonstrated that there is a seasonal variation in the asthma attacks reaching its peak in December, and the lowest in June. In conclusion, in the city of Ponce, Puerto Rico, emergency department usage due to asthma attacks show a seasonal variation, and males are more affected by asthma at younger ages while females are more affected at older ages. These findings strongly suggest that emergency department usage due to asthma attacks is highly common and represents an important place where specialized health care delivery is needed. With the implementation of dedicated asthma centers, specialized health care delivery can be easily accomplished. In addition, our data supports the that asthma should be declared a public health problem and a reportable disease.     

Expanding tuberculosis case detection by screening household contacts

OBJECTIVES: Tuberculosis (TB) case detection remains low in many countries, compromising the efficacy of TB control efforts. Current global TB control policy emphasizes case finding through sputum smear microscopy for patients who self-report to primary health centers. Our objective was to assess the feasibility and yield of a simple active case finding strategy in a high incidence population in northern Lima, Peru. METHODS: We implemented this pilot strategy in one health center's catchment area. Health workers visited household contacts of new TB case subjects to identify symptomatic individuals and collect sputum for screening. Neighboring households were screened in the same manner. Secondary analyses measured risk of TB by (1) sputum smear status of the index case subject, (2) compliance with testing, and (3) risk factors for disease detected through active contact tracing in contrast to self-report. RESULTS: The TB prevalence detected through combined active and passive case finding among 1,094 household contacts was 0.91% (914 per 100,000), much higher than with passive case finding alone (0.18%; 183 per 100,000; p=0.02). Among 2,258 neighbors, the combined strategy detected a TB prevalence of 0.22% (221 per 100,000) in contrast to 0.08% (80 per 100,000) detected through passive case finding alone (p=0.25). Risk factors for being diagnosed through active case finding in contrast with self-report included age >55 years (odds ratio [OR]=5.5; 95% confidence interval [CI] 1.2, 22.8) and female gender (OR=3.9; 95% CI 0.99, 22.3). CONCLUSIONS: Risk of active TB among symptomatic household contacts of active case subjects in this community is very high. Results suggest that contact tracing in such settings may be a powerful means of improving case detection rates for active TB disease.     

Colciencias and disdain for Colombian scientists: from the Stone Age to the impact factor

Writing has dramatically evolved in the world; however, qualification of scientific production in Colombia has not, including the improper use of decree 1444/93 and 1279/02. The last of these decrees authorized Colciencias, the Colombian government institute created to support scientific research in Colombia, to establish rules for its implementation. Colciencias decided to evaluate scientific papers produced in Colombia based on the non-scientific method of the "impact factor", and considered that citations in MEDLINE/PubMed and PsylNFO were second line publications thus violating Colombian law. This affects not only the progress of scientific research in Colombia but also researchers' income and puts Colombia's scientific journals and publications at great disadvantage. Scientific papers indexed in qualified databases such as MEDLINE/PubMed must be judged according to law in order to prevent further injuries to the developing Colombian scientific production.