B. W. Lee

Prevalence and severity of asthma, rhinitis, and eczema in Singapore schoolchildren.

This study was part of an international effort to evaluate the epidemiology of asthma and allergic diseases around the world. The aim was to assess the prevalence and severity of these disorders in Singapore schoolchildren. The international study of asthma and allergies in childhood (ISAAC) written questionnaire was administered to 6238 schoolchildren. The respondents were parents of a 6-7 year cohort (n = 2030), and schoolchildren aged 12-15 years (n = 4208). The overall cumulative and 12 month prevalence of wheezing were 22% and 12%, respectively. The prevalence of doctor diagnosed asthma was 20%. Rhinitis was reported by 44% and chronic rashes by 12%. Multiple logistic regression analysis showed that a higher prevalence of wheezing and rhinitis was associated with males, and subjects of higher socioeconomic status (based on type of housing and total family income). More severe asthma related symptoms were present in Malays and Indians than in the Chinese. Allergic disorders are common in Singapore and prevalence is comparable to some populations in the West. Demographic and socioeconomic factors appear to influence the prevalence and severity of these disorders.

PATTERN OF FOOD-INDUCED ANAPHYLAXIS IN CHILDREN OF AN ASIAN COMMUNITY

a tricyclic antidepressant. In week 4 of the treatment with phenytoin, the patient developed in 24±48 h fever of 398C combined with generalized erythematous skin rash. The other systemic and neurologic probes were normal. The blood cell count showed leukocytosis with eosinophilia (16 500 leukocytes/mm, 12% eosinophils), and the coagulation study, biochemical and hepatic pro®le, hemocultures, coprocultures, and urocultures then done, as well as the chest radiography, were normal. Computed tomography of the skull described the continuity to a parietal level without any other important alteration. With the clinical suspicion that there was an adverse reaction to medication, the phenytoin and the tricyclic antidepressant were stopped. During the following week, the patient continued to show fever and eosinophilia, and the skin rash became desquamative. The clinical situation worsened gradually and between days 8 and 10 after stopping the phenytoin, she showed acute hepatic failure with high cytolysis and cholestasis (glucose 57 mg/dl, SGOT 1535 U/l, SGPT 497 U/l, gamma GT 1055 U/l, alkaline phosphatase 662 U/l, cholesterol 110 mg/dl, total bilirubin 17.5 mg/dl, LDH 2862 U/l, albumin 1.7 g/dl), linked to severe coagulopathy (prothrombin Ac. 21%, APTT 53/29). The analysis then done did not reveal any indication of a possible cause, and the abdominal echography showed only a spleen slightly increased in size. In the following days, the patient developed acute renal failure and pancytopenia with severe neutropenia (2400 leukocytes/mm with 190 neutrophils, 10 000 blood platelets/mm, hemoglobin 8.9 g/dl). The patient died 15 days after stopping the phenytoin. The autopsy showed submassive hepatic necrosis linked to splenomegaly, and moderate in ̄ammatory in®ltrated vascular congestion of the skin. The anatomopathologic diagnosis was phenytoin hypersensitivity syndrome. Phenytoin is an anticonvulsant affecting hepatic metabolism. Among its more frequent side-effects are gastric intolerance, skin rash, and gingival hyperplasia. Less frequently, cases of hypersensitivity syndrome to DFH have been described. This syndrome with anticonvulsants was ®rst described in 1950 by Chaiken et al. (1); they called it dilantin hypersensitivity syndrome. Later, cases involving carbamacepine, primidone, and phenobarbital were described. The hypersensitivity syndrome to phenytoin is of low incidence (1/1000±10 000 treated with DFH), and it usually appears between weeks 1 and 4 of treatment. Risk factors have not been clearly identi®ed when they appeared and their origin is not dose dependent. Skin signs were the most common in the syndrome in the study by Silverman (2). Fever, lymphadenopathies, and megalies are common, as well as leukocytosis and eosinophilia. Aplastic marrow and hepatic affectation are less common. Those rare signs appear late during the development of the syndrome, and most of the patients who develop them have previous skin alterations. The pathogenic mechanism of this syndrome has not been established. Most of the facts suggest a hypersensitivity phenomenon, although idiosyncratic and toxic mechanisms with enzymatic induction of Cp 450 and the production of intermediary metabolites have also been involved. These metabolites are potentially cytotoxic, and they can alter the lymphocytic function, increasing the hepatocellular necrosis and lymphadenopathies, as described by Haword et al. (3). The diagnosis of this syndrome is clinical and analytic. Studies of lymphocytic stimulation and the patch test can indicate the therapeutic option of withdrawal of DFH, although the patients condition can alter. This emphasizes the danger of a premature diagnosis. Steroids are usually used during the treatment, although their indexing is not well established and does not alter the mortality rate. However, they are effective in the skin symptoms and can shorten their course. Excessive medication taken with DFH can worsen the prognosis. Dreifuss et al. (4) have shown cross-reactivity with other anticonvulsants and interaction with antidepressants. The mortality rate in this syndrome rises to 30±40% if hepatic damage occurs. Mullick (5), in a clinical pathologic study, has reported 20 cases of hepatic injury associated with diphenylhydantoin; the mortality rate without hepatic affectation was 10%. Our patient showed hypersensitivity syndrome to DFH after 4 weeks of treatment. She developed fever, desquamative erythema, and eosinophilia linked to aplastic marrow and severe hepatic failure, which caused her death.

Use of hypoallergenic formula in the prevention of atopic disease among Asian children.

Objective: To determine the effect of a partially hydrolysed formula on genetically predisposed children, with respect to the development of atopic clinical manifestations and in vitro testing of serum IgE levels (total and milk‐specific).

Evaluation of the allergenicity of tropical pollen and airborne spores in Singapore

Background: Sensitization to pollen and spores of the Southeast Asian tropical region is not well documented. This study evaluated the allergenicity of the tropical airspora in Singapore.

Genetic susceptibility to asthma and atopy among Chinese in Singapore: linkage to markers on chromosome 5q31-33

Background: Asthma and atopy are complex genetic traits, influenced by the interaction of multiple genes and environmental factors. Linkage of these traits to chromosome 5q31–33 has been shown in other populations, but has not been well studied in the Chinese. We studied linkage between asthma and atopy with markers on chromosome 5q31–33 in the Singapore Chinese. This region contains many candidate genes, including the cytokine gene cluster.

Characterization of glutathione S‐transferase from dust mite, Der p 8 and its immunoglobulin E cross‐reactivity with cockroach glutathione S‐transferase

Background Sensitization to mite and cockroach allergens is common, and diagnosis and therapy of allergy can be further complicated by the presence of allergen isoforms and panallergens. Purified recombinant and native allergens are useful for studies to resolve such problems.

The upper and lower airway responses to nasal challenge with house-dust mite Blomia tropicalis

Background: The house dust mite Blomia tropicalis (B. tropicalis) was found to be the most prevalent domestic mite in Singapore. However, its pathogenicity in allergic airway diseases remains to be investigated.

Lack of human IgE cross-reactivity between mite allergens Blo t 1 and Der p 1

Background:  The group 1 mite allergens are the most significant indoor allergens and they belong to the papain‐like cysteine protease family. To date there is only one published report on the isolation and characterization of group 1 allergens from Blomia tropicalis mites. The aims of the study are to determine the cross‐reactivity between group 1 allergens and to evaluate their clinical importance in allergic patients.

Comparative allergenicity studies of native and recombinant Blomia tropicalis Paramyosin (Blo t 11)

Background: The complementary DNA (cDNA) encoding for Blo t 11, a 102 kD allergen from Blomia tropicalis (Bt) was isolated, expressed and characterized previously. This study aimed to isolate the native Blo t 11 allergen and compare its allergenicity with the recombinant forms.

Sensitization profiles of Malaysian and Singaporean subjects to allergens from Dermatophagoides pteronyssinus and Blomia tropicalis.

Background: The house dust mites Dermatophagoides pteronyssinus (Der p) and Blomia tropicalis (Blo t) are the most common house dust mite species in Southeast Asia. To date, there have only been a few studies on the sensitization profile of the general populations in Southeast Asia to house dust mites. The aim of this study was to determine the profiles of Der p and Blo t sensitization among Singaporean and Malaysian subjects. Methods: Enzyme-linked immunosorbent assay was used to detect specific IgE to Der p and Blo t mite crude extracts as well as purified Der p 1, Der p 2 and Blo t 5 allergens. Sera used were from 229 Singaporean subjects (124 with rhinitis, 105 without rhinitis) and 143 Malaysian subjects (94 adults and 49 children with asthma). Results: The sensitization profile of rhinitis subjects to the dust mite allergens used in this study was as follows: Blo t extract positive: 91/124 (73%); Blo t 5 positive: 62/124 (50%); Der p extract positive: 61/124 (49%); Der p 1 positive: 53/124 (43%); Der p 2 positive: 45/124 (36%). The nonrhinitis subjects’ sensitization profile was as follows: Blo t extract positive: 60/105 (57%); Blo t 5 positive: 24/105 (23%); Der p extract positive: 38/105 (36%); Der p 1 positive: 14/105 (13%); Der p 2 positive: 17/105 (16%). The study of Malaysian asthmatic adults showed that 39% of them were sensitized to Der p 1, 32% to Der p 2 and 37% to Blo t 5. Among the asthmatic children, sensitization to Blo t 5, Der p 1 and Der p 2 was 90, 57 and 39%, respectively. Conclusion: This study clearly revealed that dual sensitization to B. tropicalis and D. pteronyssinus is common in the general populations of Singapore and Malaysia. Sensitization to Blo t 5 is more prevalent than to Der p 1 and Der p 2.