Brain stem auditory evoked response—A study in parameters

Brain stem audiory evoked response (BAER) audiometry is a non-invasive and objective measure of a subject’s auditory function. The present paper attempts to establish normative data in Indian subjects. It was found that the BAER can detect asymptomatic high frequency hearing losses. Wave V’s threshold, latency and amplitude, along with comparisons between the auditory (subjective) and BAER threshold, are useful parameters in testing for organic and non-organic hearing disorders.     

Evaluation of long-term safety of the anti-IgE antibody, omalizumab, in children with allergic asthma.

OBJECTIVE: To evaluate the long-term effects of the anti-IgE antibody omalizumab in children with asthma. METHODS: This was a 28-week, double-blind, randomized, placebo-controlled trial with a 24-week open-label extension. In the core trial 225 children (ages 6 to 12 years) with moderate-to-severe allergic asthma requiring inhaled beclomethasone dipropionate (BDP) received omalizumab every 2 or 4 weeks, and 109 received placebo. BDP dosage was stable for weeks 1 to 16, then reduced during weeks 17 to 24 using strict safety criteria. The lowest dose for optimal asthma control was maintained for 4 more weeks. During the 24-week extension, all patients (n = 309) received open-label omalizumab in addition to other asthma medications. One-year safety data were analyzed. RESULTS: The incidence of adverse events in patients treated with omalizumab for 52 weeks was similar to those treated for 28 weeks in the core trial, which was generally comparable with placebo. In the 52-week omalizumab group, upper respiratory tract infection and headache were the most frequently reported adverse events (47.1% and 42.7%, respectively). Eleven patients (4.9%) reported urticaria, which resolved spontaneously or with antihistamine, except for 1 patient who was discontinued because of severe urticaria. No anaphylactic reactions or adverse events suggestive of serum sickness or immune complex formation occurred. No anti-omalizumab antibodies were detected in any of the children. There is no evidence that new or more serious adverse events occur with long-term omalizumab treatment. CONCLUSIONS: Long-term treatment with omalizumab is safe and well tolerated in children with allergic asthma.     

Outbreak of Pichia anomala infection in the pediatric service of a tertiary-care center in Northern India

An outbreak of nosocomial fungemia due to the unusual yeast, Pichia anomala occurred in the pediatric wards of our hospital over a period of 23 months (April 1996 to February 1998). A total of 379 neonates and children (4.2% admissions) were infected. The probable index case was admitted to the pediatric emergency ward, with subsequent transmission to the premature nursery, pediatric intensive care units, and other children wards. Carriage on the hands of health care personnel was likely to be responsible for dissemination of the fungus. The outbreak could only be controlled after a health education campaign to improve hand-washing practices was instituted and after nystatin-fluconazole prophylaxis to all premature neonates and high-risk infants was introduced. In a case-control study, we identified a lower gestational age, a very low birth weight (<1,500 g), and a longer duration of hospital stay as significant risk factors associated with P. anomala fungemia in premature neonates. We conducted a culture prevalence survey of 50 consecutive premature neonates and found that 28% were colonized with P. anomala at a skin or mucosal site on the date of delivery and that 20% of these neonates subsequently developed P. anomala fungemia. We performed multilocus enzyme electrophoresis on 40 P. anomala outbreak isolates (including patient and health care workers' hand isolates), and the results suggested that these isolates were identical. Our study highlights the importance of P. anomala as an emerging nosocomial fungal pathogen.     

Immunological studies with different classes of mutants affected at the adenosine kinase locus in CHO cells

Adenosine kinase (AK) from CHO cells has been purified to homogeneity and specific antibodies to it have been raised in rabbits. Using this antibody, the presence of a specific cross-reacting protein (CRP) in cell extracts of different classes of mutants resistant to purine nucleoside analogs which are affected in AK has been investigated by the immunoblotting technique. Results of our studies show that 31 of the 32 independently selected class A AK^– mutants (obtained at high frequency in presence of adenosine analogs toyocamycin, tubercidin, 6-methylmercaptopurine riboside, or pyrazofurin and containing no measurable activity of AK in cell extracts) contained similar amounts of a specific CRP as seen in the parental AK⁺ cells. The CRP in the parental and different mutant cell lines has the same relative molecular mass as purified AK. Similar results were obtained with two mutants each of the class B and C type (selected in presence of C-nucleosides formycin A and formycin B), which are also affected in AK but show novel properties. The presence of equivalent amounts of the CRP in the vast majority of the class A mutants strongly indicates that the high frequency of those mutants in CHO cells is not a result of an epigenetic or deletion type of event, but that such mutants may contain missense types of mutations at a presumed mutational hot spot within the structural gene for adenosine kinase.     

P-glycoprotein (MDR 1 gene product) in cells of the immune system: Its possible physiologic role and alteration in aging and human immunodeficiency virus-1 (HIV-1) infection

P-glycoprotein, a 170-kd glycoprotein encoded by theMDR 1 gene, is a member of a highly conserved superfamily of ATP-binding cassette (ABC) transport proteins. It shares extensive homology with numerous bacterial and eukaryotic ABC transport proteins. P-glycoprotein acts as an energy-dependent efflux pump that appears to transport structurally diverse agents ranging from ions to peptides. P-glycoprotein (P-gP) has been implicated as playing a role in multidrug (MDR) resistance in cancer, chloroquine-resistantPlasmodium falciparum infection, and possibly human immunodeficiency virus-1 (HIV-1) resistance to nucleoside compounds. A number of normal tissues in humans and rodents have been shown to express high levels of P-gp. The expression and function of P-gp in cells of the immune system have been explored in the past 2 years. This review presents a state of the art regarding the expression, regulation, and function of Pgp in cells of the immune system. In addition, its alteration in aging and HIV-1 infection is reviewed. A possible physiologic role of P-gp in cytokine secretion, antigen processing/presentation, and effector functions is also discussed.     

Immune reactions associated with silicone-based ventriculo-peritoneal shunt malfunctions in children

The implantation of ventriculo-peritoneal (VP) shunting systems is the most commonly performed neurological procedure in children with hydrocephalus. Although the overall complication risk is low, the cumulative risk of shunt failure is high and unfortunately results in a high prevalence of revision surgeries. In this study, we explored the concept that some pediatric patients may develop an immune response to either the proteins attached to the silicone implant surface or to the biomaterial itself, and that this reaction may contribute to VP shunt failure in some individuals. The data displays that the sterile shunt malfunction group had a higher rate of protein deposition and increased levels of autoantibodies to the extracted surface proteins as compared to individuals with functioning shunting systems. The precise nature of the shunt-bound proteins that serve as antigens in this experiment have not yet been determined. The data also indicated that some individuals develop antibodies to polymeric substances that cross-react with partially polymerized acrylamide. The detection of significant amounts of shunt-bound protein, antibody responses to these proteins and to polymeric substances suggest that an immunological response to these proteins may play a role in the mechanism behind sterile shunt malfunctions.     

Aqueous polymerization of methacrylamide initiated by the redox system K2S2O8/ascorbic acid

The polymerization of methacrylamide initiated by the redox system K₂S₂O₈/ascorbic acid has been studied at 35 ± 0,2°C under the influence of atmospheric oxygen. The molecular oxygen autocatalyses the polymerization rate. The rate of polymerization is independent of the activator (ascorbic acid) concentration within the range 2,83 · 10^?3 to 11,3 · 10^?3 mol · l^?1, this does not hold below or above the given concentration range. The rate varies linearly at low monomer concentration (up to 17,76 · 10^?2 mol · l^?1). The catalyst exponent decreases from nearly unity (0,94) to 0,57 with increasing concentration of the catalyst probably due to participation of primary radicals in the termination of growing chain. The initial rate is not changed by the addition of a strong acid (H₂SO₄) within the range 15 · 10^?5 to 30 · 10^?5 mol · l^?1. With the activator (ascorbic acid) alone, an optimum is observed within the pH range 2,9–3,5. The initial rate and the limiting conversion increases with increasing polymerization temperature. The overall energy of activation as calculated from the ARRHENIUS plot has been found to be 16,0 kcal.mol^?1 within the temperature range 30–45°C. Organic solvents (water miscible only) and small amounts of neutral salts, (KCl, Na₂SO₄) depress the initial rate and the maximum conversion. The addition of small amounts of catalysts like Cu^2⊕, Mn^2⊕, Ag^oplus; increases the initial rate but no appreciable increase in the limiting conversion is observed.