Effect of electromagnetic interference by neonatal transport equipment on aircraft operation.

The number of civilian air ambulance services operating in the United States has been steadily increasing. The quantity and sophistication of electronic equipment used during neonatal transport have also increased. All medical equipment generates some electromagnetic interference (EMI). Excessive EMI can interfere with any of an aircraft's electrical systems, including navigation and communications. The United States military has strict standards for maximum EMI in transport equipment. Over the past 15 years, approximately 70% of neonatal transport monitors, ventilators, and incubators have failed testing due to excessive EMI. As neonatal transport equipment becomes more sophisticated, EMI is increased, and there is greater potential for aircraft malfunction. The Federal Aviation Administration should develop civilian standards for acceptable EMI, civilian aircraft operators must be aware of the possible dangers of excessive EMI, and equipment which does not meet future FAA standards should not be purchased.

Underdiagnosis of asthma in young adults presenting for USAF basic training.

The underdiagnosis of asthma has not been well studied previously. The purpose of this study was to determine whether the diagnosis of asthma had been made previously in young adults who were subsequently shown to have asthma upon entering military service. Questionnaires were answered by all airmen basic referred to the Allergy-Immunology Clinic at Wilford Hall United States Air Force Medical Center over an 11-month period. There were 192 airmen basic referred to rule out asthma, primarily because of respiratory symptoms with exercise. These airmen were evaluated by history, physical examination, pulmonary function tests and, in 67%, by histamine or exercise challenge test also. In those diagnosed with asthma, the evaluating allergist then determined whether the diagnosis of asthma had been made previously considered or not considered. In airmen basic diagnosed by our clinic with asthma, the diagnosis had been made previously in 45%, considered in 25%, and not considered in 30%. Undiagnosed asthmatic airmen tended to have mild and primarily exercise-induced disease. We conclude that there is a high incidence of underdiagnosis of asthma in the population studied. Exercise-induced asthma accounted for most of the undiagnosed asthma.

Allergy to beta-lactams: a survey of current practices.

Many issues related to the diagnosis and management of beta-lactam drug allergy still await definitive recommendations. To determine how practicing allergists deal with some of these dilemmas, a questionnaire was mailed to 3500 physician members and fellows of the American Academy of Allergy and Immunology. It was also sent to each of the allergy training program directors in the United States to determine what is currently taught to fellows in training. Benzylpenicilloyl-polylysine (Pre-Pen) and fresh penicillin G are used for skin testing by more than 86% of both respondent groups, whereas minor determinant mixtures are used by only 40%. Epicutaneous followed by intradermal injection was the skin test technique used by 86% of these allergists. More than 90% said they would skin test in cases of reaction history of urticaria, whereas only 1.5% would test in cases of family history of penicillin allergy. Practicing allergists and program directors differed slightly when queried about cephalosporin cross-reactivity. Program directors were more cautious in their use of cephalosporins with patients allergic to penicillin. Program directors were also more likely to repeat skin testing before future penicillin courses than were practicing allergists. Clearly, some individual approaches to the diagnosis and management of beta-lactam allergy are practiced. Development of practice guidelines by our professional organizations may be useful.

Anaphylaxis to annatto dye: a case report.

Annatto dye is an orange-yellow food coloring extracted from the seeds of the tree Bixa orellana. It is commonly used in cheeses, snack foods, beverages, and cereals. Previously reported adverse reactions associated with annatto dye have included urticaria and angioedema. We present a patient who developed urticaria, angioedema, and severe hypotension within 20 minutes following ingestion of milk and Fiber One cereal, which contained annatto dye. Subsequent skin tests to milk, wheat, and corn were negative. The patient had a strong positive skin test to annatto dye, while controls had no response. The nondialyzable fraction of annatto dye on SDS-PAGE demonstrated two protein staining bands in the range of 50 kD. Immunoblotting demonstrated patient IgE-specific for one of these bands, while controls showed no binding. Annatto dye may contain contaminating or residual seed proteins to which our patient developed IgE hypersensitivity. Annatto dye is a potential rare cause of anaphylaxis.

The effect of immunotherapy on the cutaneous late phase response to antigen.

BACKGROUND: This study used the skin chamber model to evaluate prospectively the effect of immunotherapy (IT) on the cutaneous early and late phase response (LPR) to epicutaneous antigen challenge. METHODS: Nine subjects with allergic rhinitis were studied at three time points: before starting IT, after 3 months of IT, and after 6 months of IT. Skin chamber histamine content was measured hourly for 12 hours, and cell counts performed hourly during hours 6 to 12. An intradermal skin test was placed, and the reaction was measured hourly for 12 hours. Skin biopsy specimens were obtained 8 hours after intradermal placement and evaluated for cellular infiltrate and major basic protein deposition. Serum antigen-specific IgG and IgE levels were measured at each time point to confirm physiologic effect of IT. RESULTS: Six months of IT significantly (p < 0.05) decreased both early and LPR skin test reactivity and skin chamber histamine for hours 1 to 3, 4 to 6, and 9 to 12. Skin chamber LPR cellular influx decreased significantly (p < 0.05) for neutrophils only. Decrease in LPR histamine after 6 months of IT was significantly correlated with both decrease in mononuclear cells (R2 = 0.817, p = 0.002) and decrease in neutrophils (R2 = 0.813, p = 0.009). Also significantly correlated were decrease in LPR skin test reactivity, with percent change in skin chamber mononuclear cells (R2 = 0.800, p = 0.009) and decrease in early skin test reactivity (R2 = 0.675, p = 0.01). Biopsy specimens showed no consistent change in either dermal cellular infiltrate or deposition of major basic protein. CONCLUSION: IT significantly attenuates cutaneous histamine release and skin test reactivity and is accompanied by a decrease in skin chamber LPR neutrophil influx without significantly altering the dermal infiltrate at 8 hours.

HLA-DR4-associated nonresponsiveness to mountain-cedar allergen.

We did human lymphocyte antigen (HLA)-DR and DQ typing on 37 subjects with mountain-cedar (MC) pollinosis as defined by history and a positive skin test. Of these 37 subjects, 31 were subdivided into 18 subjects with a single positive skin test (SPST) and 13 subjects with multiple positive skin tests (MPSTs). We also typed 51 subjects without MC sensitivity or atopy as defined by history and negative skin tests to a battery of aeroallergens. We also typed 116 subjects in whom MC sensitivity had not been determined. Total IgE, Mc-specific immunoglobulin E (sIgE), and MC-sIgE binding bands by immunoblot were also determined on the subjects with SPSTs and MPSTs. No significant differences were found between the subjects with SPSTs and MPSTs for HLA type, total IgE, MC sIgE, or bands bound by MC sIgE by immunoblot. There was a strong negative relationship between HLA-DR4 and subjects with MC pollinosis; chi-square, 14.857; p = 0.0096; and odds ratio, 0.139. These findings suggest that there is no difference in genetic immunoregulation between subjects with SPSTs and MPSTs but that the presence of the DR4 gene product is associated with a decreased risk of an IgE response to MC and protection from MC pollenosis.