Absence of the tag polymorphism for the risk haplotype HLA-DR2 for multiple sclerosis in Wixárika subjects from Mexico.

The HLA-DRB1*15:01 allele has a demonstrated risk for the development of multiple sclerosis (MS) in most populations around the world. The single nucleotide polymorphism (SNP) rs3129934 is found in linkage disequilibrium with the risk haplotype formed by the HLA-DRB1*15:01 and HLA-DQB1*06:02 alleles, and it is considered a reliable marker of the presence of this haplotype. Native Americans have a null or low prevalence of MS. In this study, we sought to identify the frequency of rs3129934 in the Wixárika ethnic group as well as in Mestizo (mixed race) patients with MS and in controls from western Mexico. Through real-time polymerase chain reaction (PCR) using TaqMan probes, we analyzed the allele and genotype frequencies of rs3129934 in Mestizo individuals with and without MS and in 73 Wixárika subjects from the state of Jalisco, Mexico. The Wixárika subjects were homozygote for the C allele of rs3129934. The allele and genotype frequency in Mestizos with MS was similar to that of other MS populations with Caucasian ancestry. The absence of the T risk allele rs3129934 (associated with the haplotype HLA-DRB1*15:01, HLA-DQ1*06:02) in this sample of Wixárika subjects is consistent with the unreported MS in this Amerindian group, related to absence of such paramount genetic risk factor.

Direct observation of two protons in the decay of 54Zn.

The two protons emitted in the decay of 54Zn have been individually observed for the first time in a time projection chamber. The total decay energy and the half-life measured in this work agree with the results obtained in a previous experiment. Angular and energy correlations between the two protons are determined and compared to theoretical distributions of a three-body model. Within the shell model framework, the relative decay probabilities show a strong contribution of the p2 configuration for the two-proton emission. After 45Fe, the present result on 54Zn constitutes only the second case of a direct observation of the ground state two-proton decay of a long-lived isotope.

High prevalence of infections in patients with systemic lupus erythematosus and pulmonary haemorrhage.

The main objective of this study is to describe the presence of infections in patients with pulmonary haemorrhage and systemic lupus erythematosus. Patients with systemic lupus erythematosus and pulmonary haemorrhage were thoroughly evaluated in the first 48 hours with imaging plus bronchoscopy and bronchoalveolar fluid analysis. If needed, videoassisted thoracoscopy and lung biopsy were performed too. In all, search for bacterial, mycobacterial and fungal infections proceeded. Appropriate blood, bronchoalveolar fluid and tissue cultures were taken. Patients were treated with antibiotics and corticosteroids in case of infection. Otherwise, they received initial intravenous methylprednsiolone pulses for 3 days as standard therapy for pulmonary haemorrhage in systemic lupus erythematosus. Additional treatment with immunosuppressives was further decided by the treating physicians. Fourteen events in 13 patients were evaluated. In eight events (57%), an infection was demonstrated. Aetiological agents included Pseudomonas sp. and Aspergillus fumigatus. Four patients died, three of them because of the pulmonary infection and one because of cerebral haemorrhage secondary to severe systemic hypertension, 48 hours after methylprednisolone treatment. Patients with systemic lupus erythematosus and pulmonary haemorrhage have a high prevalence of infections. The influence of pulmonary haemorrhage in the setting of systemic lupus erythematosus needs further study to establish adequate treatment and to reduce the high mortality of this complication.

First direct observation of two protons in the decay of 45Fe with a time-projection chamber.

The decay of the ground-state two-proton emitter 45Fe was studied with a time-projection chamber and the emission of two protons was unambiguously identified. The total decay energy and the half-life measured in this work agree with the results from previous experiments. The present result constitutes the first direct observation of the individual protons in the two-proton decay of a long-lived ground-state emitter. In parallel, we identified for the first time directly two-proton emission from 43Cr, a known beta-delayed two-proton emitter. The technique developed in the present work opens the way to a detailed study of the mechanism of ground state as well as beta-delayed two-proton radioactivity.

Preoperative risk factors associated with mortality in lung biopsy patients with interstitial lung disease.

The objective of this study was to evaluate the risk factors associated with mortality in interstitial lung disease patients. We performed a retrospective study of 722 consecutive patients submitted for lung biopsy during the 1986-1990 period. Twenty-two (3%) died within the 30 days following surgery. Forty-four patients who survived after the surgery for the same time span were randomly chosen as control group. Dyspnea at rest was present in 18/44 of surviving group (SG) and in 18/22 of the nonsurviving group (NSG) (OR 6.5, 95% CI 1.8-22.4,p = .001). Systemic diseases (i.e., diabetes, systemic arterial hypertension)were mainly present in the NSG (OR 7.2, 95% CI 2.3-22.8, p < .001). The SG displayed significantly less respiratory insufficiency with a PaO2 of 52.2 + 8.4 versus 38.5 i 9.4 mm Hg, and PaCO2 of 28.8 i 4.5 versus 38.5 +/- 9.2 mm Hg, respectively (p < .001). Likewise, the SG exhibited a PaCO2/PaO2 ratio of 0.5 - 0.1, while in the NSG it was of 1 +/- 0.4 (p < .001), showing a sensitivity of 84% and specificity of 93% for mortality. Multiple logistic regression analysis for these variables showed that log likelihood was still significant for PaCO2 > 34 mm Hg, PaO2 <48 mm Hg, and comorbid diseases. Logistic regression analysis of these three variables showed the greatest sensitivity and specificity (84 and 750/0,respectively) for prediction of mortality. However, the strongest association was found when PaCO2/PaO2 ratio was analyzed alone (OR 21,073,CI 95% 28-15,946,357, p < .005). These data suggest that PaCO2/PaO2 ratio appears to be a predictor of mortality in this subset of patients. Its prospective use has reduced early mortality after surgery less than 1% in the last decade.

Anesthesia for morbidly obese patients.

Bariatric surgery is the most effective method for treating patients with morbid obesity, and participation of the anesthesiologist in the treatment of these patients is more and more frequent. Therefore it is important for anesthesiologists to be familiar with anatomic and physiologic implications and the pharmacologic changes associated with obesity, so they can offer optimal perioperative treatment. The present study describes a series of 37 patients with an average body mass index of 50.3 kg/m2 who underwent bariatric surgery in a third-level teaching hospital in Mexico City. Preoperative assessment, airway management, perioperative treatment, and the incidence of complications are analyzed. We found a high frequency of associated diseases, among which diabetes mellitus and systemic arterial hypertension were the most prominent. Cardiorespiratory complications such as obstructive sleep apnea syndrome and obesity-hypoventilation syndrome were particularly frequent (16.2% and 22.0%, respectively). Both general anesthesia and mixed anesthesia (peridural block plus light general anesthesia) were employed. The incidence of complications related to perioperative and anesthetic management was low. We discuss and propose protocols for the evaluation and management of airway and associated cardiorespiratory complications.

Personal exposure to elements in Mexico City air.

Personal exposures to various metals in airborne particulates in Mexico City were measured over a seven consecutive-day period. Subjects were divided into two groups, Group A, whose work required them to spend considerable time outdoors and in traffic (messengers, delivery men, taxi drivers, salesmen), and Group B who spent most of their time indoors (university professors, consultants, managers and research workers). Group A spent 32 +/- 8.5% of their time outdoors, while Group B spent 10.7 +/- 6.7% of their time outdoors. Group A had higher exposures to airborne lead, zinc, vanadium, manganese and chromium than did Group B. There was no difference between the groups with respect to airborne copper exposures. Overall exposures to the various airborne metals were: lead, 435 +/- 220 ng m-3; zinc, 361 +/- 253 ng m-3; vanadium, 23 +/- 12 ng m-3; manganese, < or = 30 +/- 25 ng m-3; chromium, < or = 8.5 +/- 5.5 ng m-3; and copper, < or = 45 +/- 32 ng m-3. A significant number of samples were below the analytical limits of detection for manganese and copper.