Hydrogen-bond directionality and symmetry in [C(O)NH](N)2P(O)-based structures: a comparison between X-ray crystallography data and neutron-normalized values, and evaluation of reliability.

For [C(O)NH](N)2P(O)-based structures, the magnitude of the differences in the N-H...O, H...O=P and H...O=C angles has been evaluated when the N-H bond lengths, determined by X-ray diffraction, were compared to the neutron normalized values and the maximum percentage difference was obtained, i.e. about 3% for the angle even if the N-H bond lengths have a difference of about 30% (0.7 Šfor the X-ray and 1.03 Šfor the neutron-normalized value). The symmetries of the crystals are discussed with respect to the symmetry of the molecules, as well as to the symmetry of hydrogen-bonded motifs, and the role of the most directional hydrogen bond in raising the probability of obtaining centrosymmetric crystal structures is investigated. The work was performed by considering nine new X-ray crystal structures and 204 analogous structures retrieved from the Cambridge Structural Database.

Logistic regression model for prediction of airway reversibility using peak expiratory flow.

BACKGROUND: Using peak expiratory flow (PEF) as an alternative to spirometry parameters (FEV1 and FVC), for detection of airway reversibility in diseases with airflow limitation is challenging. We developed logistic regression (LR) model to discriminate bronchodilator responsiveness (BDR) and then compared the results of models with a performance of >18%, >20%, and >22% increase in ΔPEF% (PEF change relative to baseline), as a predictor for bronchodilator responsiveness (BDR). MATERIALS AND METHODS: PEF measurements of pre-bronchodilator, post-bronchodilator and ΔPEF% of 90 patients with asthma (44) and chronic obstructive pulmonary disease (46) were used as inputs of model and the output was presence or absence of the BDR. RESULTS: Although ΔPEF% was a poor discriminator, LR model could improve the accuracy of BDR. Sensitivity, specificity, positive predictive value, and negative predictive value of LR were 68.89%, 67.27%, 71.43%, and 78.72%, respectively. CONCLUSION: The LR is a reliable method that can be used clinically to predict BDR based on PEF measurements.

Pulmonary function and methacholine challenge tests in patients with ulcerative colitis.

BACKGROUND: Ulcerative colitis is an inflammatory chronic disease which is believed to be a multi organ condition. The prevalence of ulcerative colitis is reportedly increasing in Iran presenting with the same clinical characteristics as in developing countries. Pulmonary manifestations of ulcerative colitis are increasingly reported. In this study, we investigated the incidence of bronchial hyper-responsiveness (BHR) in ulcerative colitis (UC) patients. MATERIALS AND METHODS: Fifty-one UC patients with definite diagnosis referred to Shariati Hospital, Tehran, Iran, were selected to be evaluated with methacholine challenge test from October 2010 to October 2011. Patients were compared for their methacholine test outcome and its association with age, sex, diagnosis time, and disease activity. RESULTS: The median age was 41 (range 15 to 65) years. The median time of diagnosis was 7 (range <1 to 16) years. Forty-five percent were females, 18% had active disease and 13% had comorbidity. Nine percent of patients with UC had abnormal PFT in our study. Three cases (5%) had bronchial hyper-responsiveness that was not correlated with sex, age, time of diagnosis, or disease activity. CONCLUSION: A small number of ulcerative colitis patients in our study had disturbed pulmonary function test which is in concord with the findings of other studies. However, higher rates of bronchial hyper-responsiveness have been reported in other studies. Confounding factors like cigarette smoking and medications, which were negative or minimal in our study, may influence the results.