Regulation of mu-opioid receptors,G-protein-coupled receptor kinases and beta-arrestin 2 in the rat brain after chronic opioid receptor antagonism

The aim of this study was to analyse the biochemical and behavioural consequences of chronic treatment with opioid receptor antagonists in rats. We have evaluated the respiratory depressant and antinociceptive effects of the mu-opioid agonist sufentanil, the density of brain mu-opioid receptors, and the expression of G-protein-coupled receptor kinases and beta-arrestin 2 in cerebral cortex and striatum, following sustained opioid receptor blockade. Our results demonstrate that 24 h after interruption of 7 days chronic infusion of naltrexone (120 microg/h), the respiratory depressant potency of the mu-opioid receptor agonist sufentanil was increased to a similar extent as the antinociceptive potency (about three-fold). This was accompanied by mu-opioid receptor up-regulation in several areas of the rat brain associated with opioid control of pain perception and breathing. Moreover, chronic treatment with either naltrexone (120 microg/h) or naloxone (120 microg/h) caused significant increases in the expression levels of G-protein-coupled receptor kinases types 2, 3, and 6, and of beta-arrestin 2 in brain cortex and striatum.Together our data suggest an increased constitutive receptor activity secondary to mu-opioid receptor up-regulation following chronic antagonist treatment.     

Housemaids and non-fatal occupational injuries

OBJECTIVE: To estimate the annual incidence of non-fatal work injuries according to sociodemographic and occupational variables among housemaids. METHODS: A community-based survey was conducted in a population of 1,650 women aged 10 to 65 years who reported a paid occupation randomly selected in a household sample of the city of Salvador, Brazil. Data was collected through individual questionnaires on living and work conditions and health status. Fisher Exact test was performed for frequency analysis. RESULTS: It was estimated an overall annual incidence of non-fatal work injuries in the study population of 5.0%, which was statistically significant (p<0.05) higher among housemaids (7.3%) than in the group with other occupations (4.5%). Half of the injuries among housemaids were not related with long-term disabilities, and 38.1% women referred not being able to work for two weeks on average after the injury. CONCLUSIONS: Housemaids represent a major contingent of the work force in Brazil and other Latin America countries. The high incidence of non-fatal work injuries in this working group reveals its public health relevance and the need for preventive programs.     

Non-fatal occupational injuries: gender and job contract differences

In Brazil, workers without a formal job contract comprise more than half of the labor force, a contingent formed mainly by women. This study presents estimates of the annual incidence of non-fatal work-related injuries and their distribution by gender and type of job contract in an urban area of Brazil. This was a community-based study with a random cluster area sample of the inhabitants from the city of Salvador, capital of the State of Bahia. The study population included all individuals from 18 to 65 years of age who reported having a paid job (n = 2,947). Data were obtained through individual household interviews. The overall estimated annual incidence rate was 5.80%, with a non-statistically significant difference between men (6.05%) and women (5.53%) or workers with (5.67%) and without (5.92%) a formal job contract. These similarities between work-related accidents across gender and type of job contract highlighted the need for greater attention to this problem among women and informal workers, who are largely ignored in official statistics.     

A role for advanced glycation end products in diminished bone healing in type 1 diabetes

The effect of type 1 diabetes on bone healing and bone formation in standardized craniotomy defects created in BALB/cByJ mice was determined. The hypothesis that advanced glycation end products (AGEs) contribute to diminished bone healing in diabetes was evaluated by assessing for the presence of the receptor for advanced glycation end products (RAGE) by immunohistochemistry in healing craniotomy defects in diabetic animals. The effect of local application of a known RAGE protein ligand, N(epsilon)-(carboxymethyl)lysine (CML)-mouse serum albumin (MSA), on craniotomy defect healing in normal animals was then assessed and compared to the effects of control MSA. Finally, evidence in support of the expression of RAGE mRNA and protein in osteoblastic cells was obtained. The results indicated that craniotomy defects in diabetic animals healed approximately 40% of the degree to which they healed in nondiabetic animals (P < 0.05). RAGE was expressed at higher levels in healing bone tissues in diabetic compared to control animals. Further studies in nondiabetic animals indicated that bone healing was reduced by 63 and 42% in lesions treated with 900 and 90 micro g CML-MSA, respectively, compared to in animals treated with MSA alone (P < 0.05). Evidence for the expression of RAGE was obtained in mouse and rat osteoblastic cultures. These results support the contribution of AGEs to diminished bone healing in type 1 diabetes, possibly mediated by RAGE.     

Extrathoracic obstruction and hypoxemia occurring during exercise in a competitive female cyclist

A 22-year-old competitive female cyclist complained of cough, chest tightness, and wheeze during high-intensity exercise that had previously been diagnosed as exercise-induced bronchospasm (EIB). A loud stridor, a sensation of her "throat closing," and severe dyspnea developed during maximal cycling exercise with concomitant reductions in both inspiratory and expiratory flow rates. A decrease of 25 L/min (26%) in minute ventilation and arterial hypoxemia (PaO(2) decrease, 93 to 76.5 mm Hg) resulted from this obstruction. Spontaneous tidal flow-volume loops (FVLs) during exercise exhibited a sawtooth pattern during inspiration, and substantial drops in flow rates after the stridor developed. However, maximal FVLs were unchanged from baseline following exercise, indicating that the obstruction was not EIB. We suggest that the continuous measurement of spontaneous breath-by-breath tidal FVLs may be a useful diagnostic tool for the identification of exercise-induced extrathoracic obstruction. Additionally, extrathoracic obstruction should be considered as an uncommon but potential cause of inadequate ventilation and arterial hypoxemia during exercise.     

Modulation of the molecular composition of large conductance,Ca(2+) activated K(+) channels in vascular smooth muscle during hypertension

Hypertension is a clinical syndrome characterized by increased vascular tone. However, the molecular mechanisms underlying vascular dysfunction during acquired hypertension remain unresolved. Localized intracellular Ca2+ release events through ryanodine receptors (Ca2+ sparks) in the sarcoplasmic reticulum are tightly coupled to the activation of large-conductance, Ca2+-activated K+ (BK) channels to provide a hyperpolarizing influence that opposes vasoconstriction. In this study we tested the hypothesis that a reduction in Ca2+ spark-BK channel coupling underlies vascular smooth muscle dysfunction during acquired hypertension. We found that in hypertension, expression of the beta1 subunit was decreased relative to the pore-forming alpha subunit of the BK channel. Consequently, the BK channels were functionally uncoupled from Ca2+ sparks. Consistent with this, the contribution of BK channels to vascular tone was reduced during hypertension. We conclude that downregulation of the beta1 subunit of the BK channel contributes to vascular dysfunction in hypertension. These results support the novel concept that changes in BK channel subunit composition regulate arterial smooth muscle function.     

Evolution of mortality attributable to tobacco in the Canary Islands (1975-1994)

BACKGROUND: The objective of this study is that of describing the death rate attributable to tobacco on the Canary Islands throughout the 1975-1994 period. METHOD: Deaths by age, sex and cause from 1975 to 1994 were obtained from the Spanish National Institute of Statistics (Natural Movement of Population). Based on the Spanish and Canary Island Health Surveys, the percentages of those who had never smoked, smokers and ex-smokers for the Canary Island population were taken by age and sex. The relative risks of death were taken from the Cancer Prevention Study II carried out in the United States. The percentages of deaths attributable to smoking were calculated for each year, sex and age group based on the attributable fraction of the population. Likewise, the trend in the death rate attributable for the time period in question was calculated and given in the form of the annual mean percentage change in the age-adjusted death rates by way of a log-linear model. RESULTS: During the 1975-1994 period, the number of deaths attributed to smoking rose by 64%. For major causes, a 108% increase in neoplasias, a 32% drop in cardiovascular diseases and a 15.5% increase in respiratory diseases were found for the period under study. The number of deaths was also found to increase with age, the 65 and over age group having been found to be that in which the most deaths caused by smoking occurred. CONCLUSIONS: On the Canary Islands, over 20% of all deaths in 1994 can be attributed to smoking. This suggests that the measures implemented to control the smoking habit are insufficient.