Alireza Karimi

Immunologic evaluation of patients with recurrent ear, nose, and throat infections.

PURPOSE In this study, we aimed to study the frequency of possible underlying immunodeficiency responsible for susceptibility to ear, nose, and throat (ENT) infection. MATERIALS AND METHODS One hundred three (72 males and 31 females) consecutive children and adult patients with history of recurrent or chronic ENT infections, referred by otolaryngologists to the Department of Allergy and Clinical Immunology, Childrens Medical Center, Tehran University of Medical Sciences (Tehran, Iran), were enrolled to the study from March 2003 to March 2006. For each patient, demographic information and medical histories of any ENT infections were collected by reviewing the patients records. We measured immunoglobulin isotype concentrations and immunoglobulin (Ig) G subclasses by nephelometry and enzyme-linked immunosorbent assay methods, respectively. Of 103 patients, 75 received unconjugated pneumococcus polyvalent vaccine, and blood samples were taken before and 21 days after vaccination. Specific antibodies against whole pneumococcal antigens were measured using enzyme-linked immunosorbent assay method. Existence of bronchiectasis was confirmed in each patient using high resolution computed tomography scan. RESULTS Among 103 patients, 17 (16.5%) patients were diagnosed to have defects in antibody-mediated immunity including 6 patients with immunoglobulin class deficiency (2 common variable deficiency and 4 IgA deficiency), 3 with IgG subclass deficiency (2 IgG2 and 1 IgG3), and 8 with specific antibody deficiency against polysaccharide antigens. In our series, bronchiectasis was detected in 5 cases associated with primary immunodeficiency. CONCLUSIONS Long-standing history of ENT infections could be an alarm for ENT infections associated with primary antibody deficiency.

An accurate evaluation method of the thermal interruption limit of power circuit breakers

In this paper, a simplified test method has been proposed and implemented for evaluating the thermal interruption capability of the power circuit breakers. It has been shown that the thermal interruption limit of the circuit breaker can be evaluated in a more accurate way using the proposed method in comparison to the conventional synthetic test methods due to the avoiding the influences of the arc voltage. To validate the proposed test circuit, a series of experiments have been carried out on a 24 kV SF6 gas circuit breaker with rated short circuit of 25 kA and the successful interruption zone in terms of the time derivative of the current before current zero (di/dt) and rate of rise of recovery voltage (dv/dt) has been determined. The experimental results are in good accordance with the theoretical model predictions.