A preliminary study of intranasal epinephrine administration as a potential route for anaphylaxis treatment.

BACKGROUND: The intranasal (IN) administration of epinephrine could be an alternative route for anaphylaxis treatment. Although IN epinephrine absorption has been demonstrated in animals, such data in humans are still lacking. OBJECTIVE: To study the pharmacokinetics of IN epinephrine absorption in humans. METHODS: Each healthy adult (n = 5) was administered IN saline, IN epinephrine at various doses (i.e., 0.3, 0.6, 1.25, 2.5 and 5 mg), and intramuscular (IM) epinephrine at 0.3 mg. Plasma epinephrine levels at baseline and various time points up to 120 minutes after administration were determined using high-performance liquid chromatography with electrochemical detection. RESULTS: Significant systemic absorption of epinephrine via IN route was observed only at the dose of 5 mg, and the absorption thereof was comparable to that of IM epinephrine; the average area-under-curve (AUC) values at 0-120 minutes for IN saline, IM epinephrine, and 5 mg IN epinephrine were 0.3, 18.3, and 19.4 ng.min/mL, respectively. In addition, the peak epinephrine concentrations and the time to reach them were also not significantly different between IM and 5-mg IN epinephrine; the corresponding values (mean ± SD) were 309 ± 88 pg/mL and 67 ± 43 min for IM epinephrine, and 386 ± 152 pg/mL and 70 ± 17 min for 5 mg IN epinephrine. CONCLUSION: This preliminary study showed that epinephrine can be significantly absorbed via the IN route in humans. However, it requires a higher IN dose (5 mg) than the usual IM dose (0.3 mg) to achieve comparable systemic epinephrine absorption.

The utility of serum tryptase in the diagnosis of food-induced anaphylaxis.

PURPOSE: This study investigates the utility of serum tryptase for the confirmation of shrimp-induced anaphylaxis. METHODS: Patients with a history of shrimp allergy and positive skin prick tests (SPT) to commercial shrimp extract were recruited for shrimp challenges. Serum total tryptase was obtained at baseline and 60 min (peak) after the onset of symptoms. RESULTS: Thirty-nine patients were challenged. There were 12 patients with anaphylaxis, 20 with mild reactions and 7 without symptoms (control group). Characteristic features and baseline tryptase were not different among the 3 groups. The peak tryptase levels were higher than the baseline in anaphylaxis and mild reaction groups (P<0.05). The delta-tryptase (peak minus baseline) and the tryptase ratio (peak divided by baseline) in the anaphylaxis group were higher than the mild reaction and control groups (P<0.01). The optimum cut-off for peak tryptase to confirm anaphylaxis was 2.99 µg/L with 50% sensitivity, 85% specificity, 3.33 positive likelihood ratio (LR) and 0.59 negative LR. The manufacturer's cut-off for peak tryptase was >11.4 µg/L with 17% sensitivity, 100% specificity, infinity positive LR and 0.83 negative LR. The best cut-off for delta-tryptase was ≥0.8 µg/L with 83% sensitivity, 93% specificity, 11.86 positive LR and 0.18 negative LR. The best cut-off for tryptase ratio was ≥1.5 with 92% sensitivity, 96% specificity, 23 positive LR and 0.08 negative LR. CONCLUSIONS: The peak tryptase level should be compared with the baseline value to confirm anaphylaxis. The tryptase ratio provide the best sensitivity, specificity, positive and negative LR than a single peak serum tryptase for the confirmation of shrimp-induced anaphylaxis.

Identification of hemocyanin as a novel non-cross-reactive allergen from the giant freshwater shrimp Macrobrachium rosenbergii.

SCOPE: Sensitization to giant freshwater shrimp Macrobrachium rosenbergii (Mr) was recently reported. However, the allergens have yet to be identified. This study aimed to identify and characterize a novel allergen of Mr shrimp. METHODS AND RESULTS: Extracted proteins were separated and purified by anion and in some experiments, size-exclusion chromatography. Serum IgE from shrimp allergic donors identified a candidate protein, which was characterized by LC-MS/MS. The specificity of IgE binding was tested using immunoblotting and inhibition ELISA. The IgE-binding profiles from 12 of 13 Mr allergic subjects that were pre-incubated with an extract of Penaeus monodon showed residual binding to ~60-80 kDa proteins. The 60-80 kDa IgE-bound proteins were fractionated in the flow-through of anion chromatography showing a high IgE reactivity. Peptides identified by LC-MS/MS showed the proteins closely match subunits of hemocyanin (Hcs). Purified Hcs from hemolymph markedly inhibited binding of IgE from sera of Mr allergic subjects to solid-phased Mr proteins in inhibition ELISA. CONCLUSION: Hcs were identified as heat-stable, non-cross-reactive, high-molecular-weight (MW) allergens from Mr shrimp. Since circulatory organs are not always removed during food preparation, high concentrations of Hcs may be present along with shrimp meat, which contains the known cross-reactive tropomyosin protein.

Determination of storage conditions for shrimp extracts: analysis of specific IgE-allergen profiles.

The consumption of shrimp is a common cause of food hypersensitivity reactions. Shrimp allergy is diagnosed using a skin prick test (SPT) as well as by food challenges. Due to the lack of a wide variety of commercial shrimp extracts for SPTs, we selected various shrimp species for the preparation of local shrimp extracts. However, optimal storage conditions for the shrimp extracts which also maintains allergenic potency has not yet been identified. The objective of the present study was to determine the potency of the shrimp extracts under different storage conditions and durations. Specific IgE-allergen profiles of eight shrimp-allergic patients were investigated by using sera incubated with extracts prepared from lyophilized raw or boiled shrimp, which were stored at 4 degress C or -20 degress C for up to 4 weeks. When stored at -20 degress C, most allergens were preserved after 4 weeks. However, storage at 4 degress C results in few allergens remaining after 2 weeks. Boiled-shrimp extracts stored at 4 degree C and -20 degress C contained higher amounts of IgE-allergen complexes than raw-shrimp extracts. Moreover, in both raw and boiled shrimp extracts, the IgE bound 36-40 kDa allergens constituted the major proteins since they were observed in all IgE-allergen profiles. In conclusion, we recommend that shrimp extracts are stored at -20 degress C for 4 weeks to prevent the loss of allergens.

A novel mutation of the CYBB gene resulting in severe form of X-linked chronic granulomatous disease.

We evaluated a boy who had multiple Salmonella septicemia, Aspergillus pneumonia and brain abscesses. His nitroblue tetrazolium (NBT) test was reportedly abnormal. The dihydrorhodamine (DHR) flow cytometry assay was compatible with typical X-linked chronic granulomatous disease (X-CGD). CYBB analysis revealed a novel complex mutation atggacg --> ttca in exon 12 (base pairs 1532-1538). As a result, 3 amino acids Tyr 511, Gly 512 and Arg 513 were deleted and replaced by 2 amino acids, Phe and Gln. The DHR and mutation analysis of his mother showed normal DHR pattern and no mutations in exon 12 of CYBB gene. In conclusion, any children with multiple Salmonella and Aspergillus infection should be suspected of CGD. NBT test, DHR assay and gene analysis are helpful toolsto confirm the diagnosis e v en i n the case of de novo mutation.