Tobacco smoking among Portuguese high-school students.

The aim of this study was to evaluate the prevalence, behavioural patterns, and determinants of smoking among a large sample of high-school students from Porto, the second largest city in Portugal, information on sociodemographic characteristics and personal history of tobacco, alcohol, coffee, and illicit drug use was obtained from 2974 students, aged 12-19 years (48.7% female, 51.3% male), using an anonymous self-administered questionnaire. Crude and adjusted odds ratios (OR) were calculated by logistic regression analysis to estimate the association between smoking and the characteristics evaluated. Overall, 35.8% students had never smoked, 39.4% had tried it ("experimental" smokers) but were not smokers, 3.3% were former smokers, 6.6% occasional smokers, and 14.9% regular smokers. The mean age for starting smoking was 13.4 +/- 2.1 years for males and 13.4 +/- 1.6 years for females. The prevalence of current smoking was higher among males than females, but the difference was not significant. Male students were significantly more likely to smoke more cigarettes per day than were females. The prevalence of smoking was significantly associated with the following variables: being aged > 12 years; having parents who had attended school for < 4 years; having a mother (OR = 1.88), siblings (OR = 1.96) or friends (OR = 1.75) who smoked; low academic performance (OR = 1.74 for one or two failures and OR = 2.27 for more than two failures at school); and consumption of coffee (OR = 2.90), alcohol (OR = 3.53), or illicit drugs (OR = 6.69). The prevalence of smoking among adolescents increased with age. There is therefore a need for school-based tobacco prevention programmes which also deal with family influences on smoking.     

Increased blood pressure in adolescents who were small for gestational age at birth: a cohort study in Brazil.

BACKGROUND: This paper studies the relationship between birthweight for gestational age and blood pressure in adolescents aged 14-15 years in southern Brazil. METHODS: A sample of 1076 adolescents belonging to a cohort of over 6000 children born in 1982 in Pelotas, southern Brazil, was studied in 1997. All households in a sample of 25% of the city's census tracts were visited and all adolescents born in 1982 were interviewed, weighed, and their blood pressures were measured twice. Data from the adolescents were linked to the database through their names and dates of births. RESULTS: High diastolic and systolic pressure (defined as >95th percentile) were significantly more frequent among adolescents who were born below the 10th percentile of birthweight for gestational age. No association was found between high blood pressure and low birthweight or preterm births. In a multiple linear regression analysis, the association between birthweight for gestational age and blood pressure was not statistically significant after adjusting for age, sex, skin colour and family income. However, when the current body mass index and height were added to the model both diastolic and systolic pressure were significantly associated with birthweight for gestational age, and adolescents who were small for gestational age at birth presented a mean elevation of 3.08 mmHg for diastolic pressure and 2.89 mmHg for systolic pressure. CONCLUSIONS: There is an inverse association between birthweight for gestational age and blood pressure during adolescence. This association, however, is only disclosed when the negative confounding effect of the body mass index is controlled for. The same association is not found when the effects of birthweight and gestational age on blood pressure are analysed separately. It appears therefore that the elevation of blood pressure during adolescence only occurs when there was intra-uterine growth retardation.     

Behavioral changes and cholinesterase activity of rats acutely treated with propoxur

Early assessment of neurological and behavioral effects is extremely valuable for early identification of intoxications because preventive measures can be taken against more severe or chronic toxic consequences. The time course of the effects of an oral dose of the anticholinesterase agent propoxur (8.3 mg/kg) was determined on behaviors displayed in the open-field and during an active avoidance task by rats and on blood and brain cholinesterase activity. Maximum inhibition of blood cholinesterase was observed within 30 min after administration of propoxur. The half-life of enzyme-activity recovery was estimated to be 208.6 min. Peak brain cholinesterase inhibition was also detected between 5 and 30 min of the pesticide administration, but the half-life for enzyme activity recovery was much shorter, in the range of 85 min. Within this same time interval of the enzyme effects, diminished motor and exploratory activities and decreased performance of animals in the active avoidance task were observed. Likewise, behavioral normalization after propoxur followed a time frame similar to that of brain cholinesterase. These data indicate that behavioral changes that occur during intoxication with low oral doses of propoxur may be dissociated from signs characteristic of cholinergic over-stimulation but accompany brain cholinesterase activity inhibition.     

Withdrawal from oral cocaine in rats: ultrasonic vocalizations and tactile startle

While anxiety appears to characterize humans who administer high doses of cocaine or experience withdrawal from cocaine, it is difficult to capture this aspect of cocaine effects in animals. The present study investigated if acute or protracted withdrawal from prolonged low-dose cocaine that is self-administered via the oral route could be detected in tactile startle and vocal distress responses of rats. Adult, male Long-Evans rats had access to cocaine solution (0.1 mg/ml) either for 24 or 4 h/day using the two-bottle choice technique. The amount of solution consumed from each bottle was measured daily for 30 or 60 days. On days 1, 3, 7, 14, 21, 28 of withdrawal, startle and ultrasonic vocal responses (USV, 15–35 kHz) were measured in response to 18 airpuff stimuli (20 psi). Rats drank an average of 5–20 mg/kg per day of the cocaine solution. On average, about half of the daily liquid was consumed from the cocaine solution-containing bottle. USVs were emitted at significantly increased rates on day 3 of withdrawal from 30 or 60 days of cocaine drinking. Startle reactions were slightly, but non-significantly increased on day 1 of withdrawal. Comparable to withdrawal from ethanol, morphine, and diazepam treatments, withdrawal from oral self-administration of low to moderate doses of cocaine increases the rate of ultrasonic vocalizations while increasing minimally the amplitude of startle responses to low-intensity tactile stimuli. Nevertheless, no correlation between the total amount of cocaine self-administered or the duration of treatment with the intensity of the withdrawal manifestations could be detected.     

Falling diarrhoea mortality in Northeastern Brazil: did ORT play a role?

The impact of oral rehydration therapy (ORT) on the recent decline in diarrhoea mortality in the northeast of Brazil was studied. Proportionate infant mortality fell from 32% in 1980 to 17% in 1989 and infant deaths attributed to diarrhoea dropped from 41% to 25%, resulting in an overall reduction of 57%. Similar decreases were observed for children aged 1-4 years. Diarrhoea admissions also fell from 57% of infant hospitalizations in 1980 to 30% in 1990. None of the other major causes of death or admissions showed such decline. ORT was introduced in the early 1980s, being used in 35% of all episodes in 1991 and in 62% of those regarded as severe by the mother. Other changes included a worsening of socioeconomic conditions and increases in water supply, vaccine coverage, breastfeeding duration and nutritional status. A simulation model estimated that changes in factors other than ORT would lead to a 21% reduction in infant diarrhoea mortality, or about one-third of the actual decline. Finally, an ecological analysis showed that ORT use rates were inversely correlated to infant diarrhoea mortality (r=-0.61; p=0.04). Despite the shortcomings of the available data, these findings suggest an important impact of ORT on diarrhoea mortality.     

Socioeconomic situation and living conditions: comparison of two population-based cohorts from southern Brazil

Socioeconomic and family characteristics of two cohorts of babies born in 1982 and 1993 in Pelotas (Southern Brazil) were compared. There were 6,011 births in 1982 and 5,304 in 1993. In relation to family income, there were fewer poor babies in 1993; 60.8 % of the families earned less than 3 times the monthly minimum wage in 1993, as compared to 69.5% in 1982. Sanitary conditions also improved over the decade, and the proportion of families with running water and flush toilets increased by 10%. On the other hand, there were no changes in the proportion of single-parent families or availability of home appliances like radios, stoves, and refrigerators. The mean number of persons per household increased from 3.0 in 1982 to 3.2 in 1993. In general, comparison of the two birth cohorts in this city suggests an improvement in quality of living over the time period for families with newborns. This finding should be taken into account when studying the evolution of health indicators over the course of the decade.