An empirical approach to the nucleation of sulfuric acid droplets in the atmosphere

We use quantum mechanical evaluations of the Gibbs free energy of the hydrates of sulfuric acid, H2SO4. nH2O and (H2SO4)2 . nH2O to evaluate an empirical surface tension for sulfuric acid-water clusters containing few molecules. We use this surface tension to evaluate nucleation rates using classical heteromolecular theory. At low temperatures (T 213 K) the nucleation rates obtained with the empirical surface tensions are signifi cantly greater than those using bulk values of the surface tension. At higher temperatures the difference disappears

Suitability of the use of low-molecular-weight heparins in the prevention of venous thromboembolism

Objetivo: Conocer la prevalencia de prescripción de heparinas de bajo peso molecular (HBPM) en la profilaxis de la enfermedad tromboembólica venosa en un hospital general, así como la adecuación a las recomendaciones de las guías de práctica clínica. Método: Estudio observacional, descriptivo, de corte transversal, tipo indicación-prescripción, con pacientes ingresados en servicios médicos y quirúrgicos. Resultados: Se incluyeron 345 pacientes. La prevalencia de prescripción de HBPM fue del 44,6% (intervalo de confianza [IC] del 95%, 39,3-50,1). Según el nivel de riesgo tromboembólico se encontró adecuación en la decisión de tratar profilácticamente (o no) en 261 casos (75,7%; IC del 95%, 70,7-80,1), en el resto la pauta de actuación no fue la adecuada, destacando 55 pacientes (15,9%; IC del 95%, 12,2-20,2) con riesgo alto a los que no se había prescrito profilaxis (infrautilización), y 29 pacientes (8,4%; IC del 95%, 5,7- 11,8) con riesgo bajo que estaban con profilaxis (sobreutilización). En los pacientes médicos la prevalencia de prescripción fue de 22,6% (IC del 95%, 16,9-29,1) y sólo el 33,3% de los de riesgo tomboembólico alto-moderado recibió profilaxis. La prevalencia de prescripción en cirugía general fue del 84,2% y en traumatología del 91,3%. Conclusiones: En pacientes quirúrgicos el nivel de profilaxis alcanzado es adecuado, pero hay un porcentaje importante de pacientes médicos con riesgo tromboembólico medio-alto, que sigue sin recibir la adecuada profilaxis (infrautilización), a pesar de las recomendaciones de consenso con amplio respaldo científico y profesional.Objective: To investigate the prevalence of low-molecular-weight heparin (LMWH) prescription in venous thromboembolism prophylaxis in a general hospital and the suitability of the recommendations from the clinical practice guidelines. Method: A descriptive, observational and cross-sectional study of the indication-prescription type, carried out on patients admitted to medical departments and for surgery. Results: 345 patients were included. The prevalence of HBPM use was 44.6% (95% CI, 39.3-50.1). Depending on the risk of thromboembolism, the decision to treat prophylactically (or not) was appropriate in 261 cases (75.7%; 95% CI, 70.7-80.1), and the action guidelines were not suitable for the remainder of patients. 55 patients (15.9%; 95% CI, 12.2-20.2) presented a high risk and were not prescribed prophylactically (underuse); and 29 patients (8.4%; 95% CI, 5.7-11.8) at low risk were treated prophylactically (overuse). There was a relationship between the appropriateness of the prescription and the type of patient (p<0.01). In the group of medical patients theprevalence of prescription was 22.6% (95% CI, 16.9-29.1) and only 33.3% of patients with a high to moderate risk of thromboembolism received prophylaxis. The prevalence of prescription in general surgery was 84.2% and 91.3% in traumatology. Conclusions: The degree of prophylaxis is adequate in surgical patients, but there was a significant percentage of medical patients with a high to moderate risk who did not receive suitable prophylaxis (underuse), despite recommendations with scientific and professional backing.Consejería de Salud de la Junta de AndalucíaInstituto de Salud Carlos II

Azathioprine response in patients with fibrotic connective tissue disease-associated interstitial lung disease

BACKGROUND: Azathioprine is a commonly prescribed therapy for connective tissue disease-associated interstitial lung disease (CTD-ILD). Combination therapy that included azathioprine was recently shown to increase the risk of death and hospitalization in patients with idiopathic pulmonary fibrosis. Whether azathioprine increases the risk of adverse outcomes in patients with fibrotic CTD-ILD, including those with CTD-associated usual interstitial pneumonia (UIP), remains unknown. METHODS: A retrospective cohort analysis was performed to determine the combined incidence rate of death, transplant and respiratory hospitalization associated with azathioprine exposure. A fibrotic CTD-ILD cohort treated with mycophenolate mofetil served as a comparator group. Incidence rates were compared with an incidence rate ratio (IRR) generated by negative binomial regression. Longitudinal pulmonary function response was then assessed using mixed effects linear regression models. RESULTS: Fifty-four patients were treated with azathioprine and forty-three with mycophenolate. Medication discontinuation due to non-respiratory side effects occurred in 27% and 5% of the azathioprine and mycophenolate cohorts, respectively. The combined incidence rate of adverse outcomes was 0.013 and 0.015 for azathioprine and mycophenolate, respectively (IRR 1.23; 95% CI 0.49-3.12; p=0.66). Similar incidence rates were observed among those with CTD-UIP (IRR 0.83; 95% CI 0.21-3.31; p=0.79). Both groups demonstrated pulmonary function stability over time, with the azathioprine group demonstrating a marginal improvement. CONCLUSIONS: A significant minority of patients could not tolerate azathioprine due to non-respiratory side effects. Of those who did tolerate azathioprine, a similar incidence of adverse outcomes was observed as those treated with mycophenolate. Both therapies were associated with stability in pulmonary function

Bronquiectasias associadas à síndrome de Sjögren Bronchiectasis associated to Sjögren syndrome: case report

Diversas formas de comprometimento pulmonar têm sido descritas na síndrome de Sjögren, incluindo raros casos em que bronquiectasias foram o achado predominante. Relata-se o caso de uma paciente com história de infecções respiratórias de repetição e dispnéia progressiva de longa evolução, cuja tomografia computadorizada de alta resolução evidenciava inúmeras bronquiectasias. A revisão de uma biópsia pulmonar realizada no início dos sintomas mostrava alterações bronquiolares de natureza inflamatória e fibrótica. Apesar da presença de sintomas de síndrome seca há anos, o diagnóstico de SS foi feito apenas tardiamente. São discutidos os possíveis mecanismos patogenéticos que possam ter levado ao desenvolvimento das bronquiectasias e a necessidade de um apurado senso clínico para o diagnóstico precoce de tais condições.<br>Different kinds of pulmonary impairment have been described in Sjögren syndrome, including rare cases of bronchiectasis. The authors report a female patient with a history of episodes of respiratory infections and progressive breathlessness whose high resolution computerized tomography revealed bronchiectasis. A former open lung biopsy showed bronchiolar inflammatory and fibrotic changes. The diagnosis of Sjögren syndrome was made only late in the evolution, although sicca syndrome symptoms had been present for years. The authors discuss the potential pathogenic mechanisms involved in the development of the bronchiectasis and the need for a high degree of clinical medical skill for the early diagnosis of such conditions