Surface coil magnetic resonance imaging of the normal larynx

The use of specialized surface coils has made it possible to obtain high-signal, high-resolution magnetic resonance (MR) images of the neck. We describe the normal anatomy of the larynx imaged with surface coils and a technique adapted from respiratory gating to reduce motion from swallowing and coughing. Compared with computed tomography, MR has superior discrimination of tissues that on computed tomography appear to be of similar density. The intrinsic laryngeal muscles and carotid sheath are well seen. Multiplanar imaging capability allows easy distinction of false and true cords and optimal evaluation of the preepiglottic and paralaryngeal spaces. Computed tomography is easier to perform than MR and is superior to MR in depicting the laryngeal cartilages. However, with improved technology, MR may become the imaging modality of choice in evaluation of the larynx and adjacent hypopharynx and subglottic regions.     

HIV-1 subtype J recombinant viruses in Spain

Genetic characterization of HIV-1 was carried out in two women who originated in Cameroon and Equatorial Guinea, respectively, and who were diagnosed more recently as HIV-1 seropositive in Madrid, Spain. Phylogenetic studies showed that the protease-encoding gene from both individuals clustered with subtype J sequences with a high bootstrap. However, env sequences clustered with subtypes A and C, respectively. This work represents the first characterization of HIV-1 containing subtype J-like genomic regions in Spain.     

Superoxide anions mediate veratridine-induced cytochrome c release and caspase activity in bovine chromaffin cells

1. Mitochondrial mechanisms involved in veratridine-induced chromaffin cell death have been explored. 2. Exposure to veratridine (30 micro M, 1 h) produces cytochrome c release to the cytoplasm that seems to be mediated by superoxide anions and that is blocked by cyclosporin A (10 micro M), MnTBAP (10 nM), catalase (100 IU ml(-1)) and vitamin E (50 micro M). 3. Following veratridine treatment, there is an increase in caspase-like activity, blocked by vitamin E (50 micro M) and the mitochondrial permeability transition pore blocker cyclosporin A (10 micro M). 4. Superoxide anions open the mitochondrial permeability transition pore in isolated mitochondria, an effect that is blocked by vitamin E (50 micro M) and cyclosporin A (10 micro M), but not by the Ca2+ uniporter blocker ruthenium red (5 micro M). 5. These results strongly suggest that under the stress situation caused by veratridine, superoxide anions become important regulators of mitochondrial function in chromaffin cells. 6. Exposure of isolated bovine chromaffin mitochondria to Ca2+ results in mitochondrial swelling. This effect was prevented by ruthenium red (5 micro M) and cyclosporin A (10 micro M), while it was not modified by vitamin E (50 micro M). 7. Veratridine (30 micro M, 1 h) markedly decreased total glutathione and GSH content in bovine chromaffin cells. 8. In conclusion, superoxide anions seem to mediate veratridine-induced cytochrome c release, decrease in total glutathione, caspase activation and cell death in bovine chromaffin cells.     

Long-term treatment with insulin induces apoptosis in brown adipocytes: role of oxidative stress

Trying to define the precise role played by insulin regulating the survival of brown adipocytes, we have used rat fetal brown adipocytes maintained in primary culture. The effect of insulin on apoptosis and the mechanisms involved were assessed. Different from the known effects of insulin as a survival factor, we have found that long-term treatment (72 h) with insulin induces apoptosis in rat fetal brown adipocytes. This process is dependent on the phosphatidylinositol 3-kinase/mammalian target of rapamycin/p70 S6 kinase pathway. Short-term treatment with the conditioned medium from brown adipocytes treated with insulin for 72 h mimicked the apoptotic effect of insulin. During the process, caspase 8 activation, Bid cleavage, cytochrome c release, and activation of caspases 9 and 3 are sequentially produced. Treatment with the caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp (Z-VAD), prevents activation of this apoptotic cascade. The antioxidants, ascorbic acid and superoxide dismutase, also impair this process of apoptosis. Moreover, generation of reactive oxygen species (ROS), probably through reduced nicotinamide adenine dinucleotide phosphate oxidases, and a late decrease in reduced glutathione content are produced. According to this, antioxidants prevent caspase 8 activation and Bid cleavage, suggesting that ROS production is an important event mediating this process of apoptosis. However, the participation of uncoupling protein-1, -2, and -3 regulating ROS is unclear because their levels remain unchanged upon insulin treatment for 72 h. Our data suggest that the prolonged hyperinsulinemia might cause insulin resistance through the loss of brown adipose tissue.     

Comparing the acute response to cadmium toxicity of nauplii from different populations of Artemia

The lethal responses to cadmium of instar II nauplii from eight populations of Artemia belonging to the species Artemia franciscana, Artemia salina, Artemia persimilis, and Artemia parthenogenetica have been compared. Generalized linear models were used to fit mortality. The model indicates that there is a relationship between species, type of population, and mortality rate. The two populations of A. franciscana were the most sensitive to cadmium toxicity (median lethal concentration, LC50, of 93.3-142 mg/L), while the population of A. persimilis was the most resistant (LC50 of 284 mg/L). Differences in the phenotypic variability in each population were assessed through the slope of the mortality curve, with A. persimilis exhibiting the highest diversity. This study suggests that habitat peculiarities and historical origin of the populations may have a significant influence on their response to cadmium toxicity.     

Biological risk factors for deep vein trombosis

Hypercoagulable states due either to inherited or acquired thrombotic risk factors are only present in approximately half of cases of DVT, but the causes in the other half, remain unknown. The importance of biological risk factors such as hyperlipidemia, hypofibrinolysis and hemorheological alterations in the pathogenesis of DVT has not been well established. In order to ascertain whether the above mentioned biological factors are associated with DVT and could constitute independent risk factors, we carried out a case-control study in 109 first DVT patients in whom inherited or acquired thrombophilic risk factors had been ruled out and 121 healthy controls age (42+/-15 years) and sex matched. From all the biological variables analyzed (cholesterol, triglycerides, glucose, fibrinogen, erythrocyte aggregation, hematocrit, plasma viscosity and PAI-1) only fibrinogen concentration reached a statistically significant difference on the comparison of means (290+/-73 mg/dl in cases vs 268+/-58 mg/dl in controls, p<0.05). After this continuous variables were dichotomized according to our reference values, the percentage of cases with cholesterolemia >220 mg/dl, hematocrit >45% and fibrinogen >300 mg/dl was higher in cases than in controls: 38% vs 22%; p<0.01; 43% vs 27%; p<0.05; 36% vs 23%; p<0.05, respectively. The percentage of cases with PAI-1 values >30 ng/ml, 37% vs 25% was borderline significant; p=0.055. Multivariate logistic regression analysis showed that cholesterolemia >220 mg/dl and fibrinogen >300 mg/dl constitute independent predictors of venous thrombotic risk. The adjusted OR's were 2.03 (95% CI; 1.12-3.70) for cholesterolemia and 1.94 (95% CI; 1.07-3.55) for fibrinogen. When these two variables combined DVT risk rose about fourfold (3.96; p<0.05). Our results suggest that hypercholesterolemia and hyperfibrinogenemia should be added to the list of known DVT risk factors and we recommend adopting measures to decrease these variables in the population with a high risk of DVT.     

Effects of DA D1 and D2 antagonists on the sensitisation to the motor effects of morphine in mice

Acute morphine administration produces hyperactivity in mice and repeated treatment induces an enhancement of this effect. In this experiment, we study the sensitisation to the hyperactivity induced by intermittent morphine administration (40 mg/kg) and the effects of dopamine (DA) antagonists on this phenomenon. Animals received three injections, separated by 48 h, and after each injection, their activity was registered between 30 and 60 min. In Experiment 1, animals were divided into two groups, which received saline and morphine (S–S–M) or only morphine (M–M–M). In Experiment 2, animals were divided into 12 groups. Half, which was designed to study the effects of DA antagonists on the acquisition of morphine sensitisation, received morphine plus 0.125, 0.25, or 0.5 mg/kg SCH 23390 or raclopride in the two first administrations and only morphine in the third (M+SCH–M+SCH–M; M+R–M+R–M). The other groups, designed to study the effects of DA antagonists on the expression of morphine sensitisation, received morphine in the two first administrations and morphine plus DA antagonists in the last injection (M–M–M+SCH; M–M–M+R). Intermittent morphine administration produces greater hyperactivity than acute morphine. DA D1 antagonists reduce acquisition and block expression of sensitisation, while DA D2 antagonists only affect expression with the intermediate and high dose. These results support the implication of DA in the behavioural sensitisation of morphine in mice.