Nanoindentation characterization of the micro-lamellar arrangement of black coral skeleton.

Black corals (antipatharians) are colonial cnidarians whose branched tree-like skeleton is mostly constituted of chitin fibrils inside a lipoproteic matrix. The skeleton exhibits growth rings formed by chitin layers (micro-lamellae). In order to know the effect of the arrangement microlamellae of chitin of black corals and to improve the understanding of the role of chitin structure in the antipatharian skeleton, the mechanical properties of the skeleton of two black corals, Antipathes caribbeana and Antipathes pennacea, were examined using nanoindentation tests. Measurements of reduced elastic modulus, nanohardness and the viscoelastic behavior were measured with a spheroconical indenter. The results indicate variations in the values of the mechanical properties clearly associated with different structures present in the skeletons, the core being the one that invariably shows the maximum values. The solid multilamellar arrangement of black coral chitin, its viscoelastic behavior, and the anisotropic mechanical response, are relevant factors contributing to the successful adaptation of black coral colonies to shallow as well as to very deep waters.

Cigarette smoking; knowledge and attitudes among Mexican physicians.

OBJECTIVE: To determine the prevalence of the smoking habit among Mexican physicians as well as some of their attitudes and information on specific issues concerning smoking. MATERIAL AND METHODS: In 1993, a survey was carried out among 3,568 physicians of the three major official health care institutions in Mexico City. A questionnaire designed for The Mexican National Survey of Addictions (ENA 1993) was used. Prevalence of cigarette smoking, age of onset, number of cigarettes per day; also information and attitudes concerning smoking were assessed. RESULTS: The mean age was 37, 66% were males. Of the 3,488 (98%) surveyed, 26.9% were smokers (62% daily), 20.6% were ex-smokers and 52.5% non-smokers. There were differences related to age and sex (p < 0.05). Of daily smokers, 36% smoked between 1 and 5 cigarettes. There was a significant trend among ex-smokers that linked the time they had ceased smoking with the fear to start smoking again. Physicians were well informed of the relationship between cigarette smoking and lung cancer. Over 80% considered tobacco an addictive drug but only 65% were in favor of banning smoking from their workplaces and over 10% were not aware that it is forbidden to smoke inside health care facilities. CONCLUSIONS: These results differ from other studies that find the prevalence of smoking among physicians lower than in the general population. Our study revealed a greater prevalence of the smoking habit among female physicians and the number of cigarettes smoked per day was greater than in the general population regardless of sex.

[Consumption of prescription drugs in 60-65 years old population in Mexico. National Survey on Addictions, 1993]. / Consumo de drogas médicas en poblacion de 60 a 65 años en México. Encuesta Nacional de Adicciones 1993.

OBJECTIVE: To estimate the prevalence of consumption of medical drugs among the population 60 to 65 years old identified in the National Survey on Addictions 1993 and obtain data on the demographic characteristics of these consumers. MATERIAL AND METHODS: A cross-sectional, probabilistic, stratified and cluster sample of subjects between 12 and 65 years old living in urban areas of the country was selected. RESULTS: Of the 911 elderly subjects identified, 218 (23.9%) were consumers of prescription drugs, constituting 17% of men and 28% of women. The most frequently used drugs were central nervous system depressants (22% of women and 13% of men) followed by opiates (7% of women and 5% of men). The onset age of consumption was 60 years old and men started earlier than women. Of prescription drug users, 85% use depressors and opiates by prescription, 3% self-medicate themselves and 5% follow a friend's recommendation. Nine per cent use prescription drugs longer than the prescribed time. CONCLUSIONS: More extensive, specific studies of drug consumption by the elderly should be carried out to explore prevalence of use, which are used most frequently, frequency of adverse effects, effects on quality of life and social support networks for the elderly, among other topics.

Risk factors for inhalant abuse in juvenile offenders: the case of Mexico.

During the last two decades the abuse of inhalants and other addictive substances has received considerable attention in Mexico. Although substance abuse seems to affect everyone, adolescents seem to be at higher risk, and although researchers have identified the links between substance abuse and delinquency, there is not enough scientific information to explain the reason. A cross-sectional study was designed to examine the relationship between known risk factors and inhalant abuse among a group of Mexican juvenile offenders. Of the 626 subjects studied, 58% reported use of different drugs, and of them 23% abused inhalants. Gender, low socio-economic level and labor status were the principal risk factors associated with inhalant abuse. According to attributable risks calculated, and taking into account the methodological limitations of the study, the authors suggest some preventive actions to decrease inhalant abuse in the population studied.

[Clinical and epidemiological aspects of tuberculosis in children]. / Algunos aspectos clinico-epidemiologicos de la tuberculosis en ninos.

PIP: Survey data, statistics on reported cases of tuberculosis in the Dominican Republic, and the epidemiological features of cases hospitalized at a pediatric hospital in Santo Domingo are analyzed in an effort to assess the status of tuberculosis among children in the country in the past several years. Morbidity data indicate an increase in the rate of pulmonary tuberculosis from 17.6/100,000 in 1973 to 49.2/100,000 in 1984. The mean and median rates were 43.6 and 41.1/100,000 in 1982-86. The mortality rate remained stable from 1970-82 with a mean of 6.3/100,000 and a median of 6.1/100,000. Morbidity rates for pulmonary tuberculosis showed a declining trend for children under 15 and an increase for persons over 15 in the past 6 years. There were decreases in reported cases of nonpulmonary tuberculosis in all age groups. Population studies of the prevalence of pulmonary tuberculosis are very rare. A 1984-85 study of 2416 individuals over age 15 in Santo Domingo suggested an incidence of 60 cases per 100,000. Reports of the Saint Socorro Pediatric Sanatorium show a moderate increase in hospitalized cases in the past 4 years but a reduction in the proportion of occupied beds. There were 695 hospitalized cases in 1981-86. 235 were in children 1-4, 197 in those 10-14, 162 in those 5-9, 53 in infants under 1 year, and 48 in children over 15. 50 of the 695 children died, for an overall case-fatality rate of 7.2%. The greatest mortality was in infants under 1 (15%), with a progressive decline by age groups to 8% for children 1-4, 5% for children 5-0, 5.6% for those 10-14, and 0 in those 15 and over. Miliary and meningeal forms had the highest fatality rates at 21.6% and 26.5% respectively. Case reporting is incomplete and official statistics must be interpreted with great caution.^ieng