Err-Lieh Hsu

Sensitization to Blomia tropicalis among Asthmatic Patients in Taiwan

House dust mites have been reported as one of the most important allergens in Taiwan especially in asthmatic patients. This study was conducted to determine the allergenicity of Blomia tropicalis and sensitization of asthmatic patients in Taiwan. Serial dust samples were collected every month between July 1993 and June 1994 from 13 houses of mite-allergic patients. About 1 m2 surface area of a quilt was vacuumed. The floating method was used to collect mites, then identification and counting were performed. Results showed that Dermatophagoides pteronyssinus and B. tropicalis were the two most common species of mites found in allergenic patients’ houses in Taipei. D. pteronyssinus accounted for 52.1% of the total number of mites and was found in every house. B. tropicalis, although not present in every sample, accounted for 44.3% of the total number of mites. The skin test positive reaction to B. tropicalis, D. pteronyssinus and Dermatophagoides farinae were 73.3, 88.3 and 85.0% as determined from 60 allergic patients who attended our allergy clinics. The extract prepared from B. tropicalis was used to determine the allergenicity and contained at least 30 protein components when silver stained. The most frequently detected allergens were proteins with molecular weights of 14.3, 106.5, 94.0, 72.0, 91.9, 63.7, 100.3, 43.6, 27.3, 62.0, 34.7, 18.3, 41.1 and 21.9 kD. The frequency of IgE binding of patient sera to those proteins were 87.0, 65.2, 56.5, 43.4, 39.1, 39.1, 34.8, 30.4, 30.4, 17.4, 17.4, 17.4, 13.0 and 8.7%. The results from immunoblot inhibition showed that there was IgE cross-reactivity among the B. tropicalis and D. pteronyssinus. However, there were two major allergenic components of B. tropicalis not inhibited by D. pteronyssinus with molecular weights of about 14.3 and 27.3 kD. The use of B. tropicalis extract for diagnostic purposes to identify patients with specific sensitivity should be considered in Taiwan.

Differential survival of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) larvae exposed to low temperatures in Taiwan

Abstract Aedes aegypti (L.) and Aedes albopictus (Skuse) differ in their distribution in Taiwan. The former species is distributed in the south of Taiwan, whereas the latter is found throughout the island. One possible explanation proposes that low temperatures in the winter prevent the expansion of Ae. aegypti. Hence, the impact of low temperatures on immatures of both species was studied in the laboratory and in the field. Our study showed that, under most conditions, Ae. aegypti were more sensitive to low temperatures than Ae. albopictus both in the laboratory and in the field. The survival rates at 10°C for the first and fourth instars of Ae. albopictus were significantly better than those of Ae. aegypti. At 2.5 and 5.0°C, the first instars of Ae. albopictus survived better than the same stadium of Ae. aegypti, but the fourth instars of Ae. aegypti survived better. Short exposures to low temperatures did not affect the acclimatization of Ae. aegypti immatures but longer exposures did increase the physiological adaptation to low temperatures. For Ae. albopictus, exposure to low temperatures increases the acclimatization of this species. In field experiments, Ae. aegypti larvae had a significantly higher mortality than Ae. albopictus during exposures to cold fronts in the 2004 winter. We conclude that low temperatures in northern and central Taiwan have a negative impact on the distribution of Ae. aegypti, but this factor alone is not sufficient to prevent this species from occupying the rest of Taiwan.

Immunologic characterization and allergenicity of recombinant Tyr p 3 allergen from the storage mite Tyrophagus putrescentiae.

Background: The involvement of the storage mite Tyrophagus putrescentiae in allergies has been increasingly reported in many countries. Molecular analysis has shown that group 3 mite allergens are homologous to trypsin. Similar allergens have not been identified in T. putrescentiae. Our aims were to characterize group 3 allergens in T. putrescentiae and to investigate their significance in allergenicity. Methods: cDNAs of PreTyr p 3 and rTyr p 3 from T. putrescentiae were cloned and expressed in Escherichia coli. Native Tyr p 3 (nTyr p 3) was purified from spent growth medium with an affinity column coupling of antibody. Biological activities of rTyr p 3 were compared with nTyr p 3 in terms of IgE activity, enzymatic activity and histamine release. Results: Full-length cDNA of PreTyr p 3 encodes a 285-amino acid trypsin-like protease and acquires enzymatic activity after removing the pre- and pro-sequences. rTyr p 3 is a 26-kDa protein with equivalent IgE reactivity but weaker enzymatic activity than that of nTyr p 3. A limited level of cross-reactivity has been found between rTyr p 3, Der p 3 and Blomia. Eight of 10 T. putrescentiae-sensitized individuals showed >50% histamine release after triggering with rTyr p 3. Conclusions: Our studies demonstrate that Tyr p 3 is a frequent allergen (58%) in T. putrescentiae-sensitized patients. Since rTyr p 3 displays equivalent biological activities as nTyr p 3, the role of group 3 allergens can be studied using rTyr p 3 to elucidate the pathogenic effects and diagnostic applications of Tyr p 3.

The differences of dengue vectors and human behavior between families with and without members having dengue fever/dengue hemorrhagic fever.

Dengue vectors, human knowledge and behavior have been reported to play an important role in the transmission of dengue. This study was designed to understand the differences of dengue vectors and the behavior between families with (target group) and without (control group) members having dengue fever/dengue hemorrhagic fever. Population density of dengue vectors were determined by ovitrap index. The living conditions, knowledge, and behavior related to dengue were investigated by questionnaire survey. Long-term ovitrap indices obtained in the target group was significantly higher than those obtained in the control. Most of the respondents had sufficient knowledge about the transmission and prevention of dengue. However, only low percentages of the families frequently cleaned water-filled containers and ditches around their residence, especially in the target group. These findings indicate that higher indices of dengue vectors and dengue-related behavior are important in the transmission of indigenous dengue.

Insecticide resistance in German cockroaches (Blattella germanica) from hospitals and households in Taiwan.

Since a high percentage of cockroach infestation has been determined in hospitals in Kaohsiung, South Taiwan, insecticide resistances may have developed in the cockroach populations. To determine the resistances in cohorts of German cockroach (Blattella germanica) from hospitals and households to organophosphates, carbamates and pyrethroids, cockroaches were trapped from 30 hospitals and 30 households in this area. Bioassays by topical application were then carried out on the first generation bred in the laboratory. Resistance ratio (RR) was determined by comparing the LD50 of the collected cohorts with that of a susceptible cohort. RR ranges of chlorpyrifos, propoxur and cypermethrin in the hospitals were 2.04-28.80, 2.86-30.86 and 1.95-14.05 and those in the household were 1.92-17.72, 6.93-62.50 and 2.80-27.35 respectively. Significant correlations among the RRs of the three insecticides were separately found in the hospitals and households, indicating the existence of cross resistance among the three groups of insecticides. The patterns of propoxur > chlorpyrifos > cypermethrin in hospitals and propoxur > cypermethrin > chlorpyrifos in households reflect that chlorpyrifos is more frequently used in hospitals than in households. In contrast, cypermethrin is used more frequently in households.

Seaport as a source of hantavirus: A study on isolated isles

Abstract Since small mammals from seaports have relative higher seroprevalences of hantavirus, this seroepidemiologic study was conducted on the isles in Kinmen and Lienchiang Counties along the coast of southern mainland China to determine whether seaport may play the role as a source of hantavirus. Among six species of small mammals trapped in Kinmen County, only male Mus musculus (6.7%) and Rattus losea (5.3%) were found to be positive. In Lienchiang County, five species of small mammals were trapped and positive findings were obtained only in male R. norvegicus (9.3%), male M. musculus (7.7%), and female R. losea (1.6%). There was no significant difference in the seroprevalence between the two counties (Kinmen 3.8% vs. Lienchiang 3.9%). The positive rate in Liaolo (17.9%) of Kinmen County was significantly higher than the remaining trapping stations and those in Matsu Distillery (10.3%) and Fushing (5.8%) of Lienchiang County were significantly higher than the remaining ones. Moreover, a significant inverse correlation was found between the seropositive rate and the distance of small mammal sampling sites to the seaport (p < 0.01). These findings suggest the role of seaport as a source of hantavirus.

Evidence for the Site of Female Sex Pheromone Production in Periplaneta americana

We used bioassays to determine the sex pheromone production site in the female American cockroach (Periplaneta americana). Bioassayed extracts from various body parts aroused sexual responses from unmated males. However, the extract of hindgut (including both colon and rectum) induced strong responses. Colon extract stimulated the strongest sexual response. To compare the sex pheromone contents of atrial glands, pygidium, rectum, and colon, we recorded the EAG responses of male antennae to these extracts. Among the four tissues, colon extract caused the strongest EAG response. From gas chromatographic (GC) analysis, the quantities of periplanone-A (PA) and periplanone-B (PB) (the main sex pheromone components in female American cockroach) were 0.34 and 8.31 ng, respectively, in the colon of a virgin female. The ratio of PA to PB was ca. 1:24. The present results are different from those reported in a previous study, in which it was concluded that atrial glands are the sites of sex pheromone production in P. americana, and from GC analysis the quantity of PB was estimated to be 60 ng/female. There was no difference in sexual behaviors induced by colon and atrial glands of calling virgin females. It is unclear whether the colon is the sole sex pheromone source in the female American cockroach.

Voltage-dependent calcium channels in the corpora allata of the adult male loreyi leafworm, Mythimna loreyi

In the corpora allata (CA) of the adult male loreyi leafworm, Mythimna loreyi, juvenile hormone acid (JHA) biosynthesis and release show a dose dependence on extracellular Ca(2+) concentration. Maxima are obtained with Ca(2+) concentrations of 2-10 mM, and synthesis and release are significantly inhibited under a Ca(2+)-free condition. The Ca(2+)-free inhibition of JHA release can be reversed by returning the glands to medium at 5 mM Ca(2+). The cytosolic free Ca(2+) concentration ([Ca(2+)](i)), which was measured with fura-2, in individual CA cells also shows a dose dependence on extracellular Ca(2+) concentration, with significant [Ca(2+)](i) depression being observed in the absence of extracellular Ca(2+). High K(+) significantly increases the JHA release and causes a transient [Ca(2+)](i) increase within seconds in CA cells. High-K(+)-stimulated JHA release is partially inhibited by the benzothiazepine (BTZ)-, dihydropyridine (DHP)- and phenylalkylamine (PAA)-sensitive L-type voltage-dependent calcium channel (VDCC) antagonists diltiazem, nifedipine and verapamil, respectively; by the N- and P/Q-type VDCC antagonist omega-conotoxin (omega-CgTx) MVIIC; and by the T-type VDCC antagonist amiloride. The N-type antagonist omega-CgTx GVIA is the most potent in inhibiting the high-K(+)-stimulated JHA release. No inhibitory effect is shown by the P-type antagonist omega-agatoxin TK (omega-Aga TK). The high-K(+)-induced transient [Ca(2+)](i) increase is largely inhibited by the L-type antagonists (diltiazem, nifedipine, verapamil), by the N- and P/Q-type antagonist omega-CgTx MVIIC and by the T-type antagonist amiloride, and is totally inhibited by the N-type antagonist omega-CgTx GVIA. No inhibitory effect is shown by the P-type antagonist omega-Aga TK. We hypothesize that L-type, N-type and T-type VDCCs may be involved to different degrees in the high-K(+)-stimulated JHA release and transient [Ca(2+)](i) increase in the individual CA cells of the adult male M. loreyi, and that the N-type VDCCs may play important roles in these cellular events.