Novel and highly sensitive immunoassay for total hepatitis B surface antigen, including that complexed with hepatitis B surface antibody.

BACKGROUND: Hepatitis B surface antigen (HBsAg) is used as a clinical marker of hepatitis B virus (HBV) infection. However, conventional HBsAg assays have so far failed to accurately detect HBsAg in blood because of interference by patient-derived antibodies against HBsAg (HBsAb). METHODS: We developed a novel, fully automated assay system that can detect total HBsAg in blood, including antigens complexed with HBsAb. The immunoassay inactivates HBsAb via a simple pretreatment step to dissociate the HBsAg molecule from HBsAg-HBsAb complexes and thereby estimate total HBsAg. Accordingly, the test has been termed the "immunoassay for total antigen including complex via pretreatment (iTACT)-HBsAg." RESULTS: The recovery rate of HBsAg in the presence of HBsAb was greater than 87 % at a cutoff value set at 5.0 mIU/mL on the basis of data from 545 healthy controls. Analyses using serial serum samples from 25 HBV carriers who became negative for HBsAg during follow-up showed that the iTACT-HBsAg could detect HBsAg over a period of years despite a loss in detection by conventional assays and was able to detect HBsAg in 39 (53 %) of 73 samples with HBsAb. CONCLUSIONS: The new iTACT-HBsAg assay appears to detect total HBsAg with high sensitivity, even in the presence of HBsAb, and may useful in identifying subclinical or occult HBV carriers.

Effects of indomethacin on patent ductus arteriosus in neonates with genetic disorders and/or congenital anomalies.

OBJECTIVES: The study aimed to evaluate the effectiveness of intravenous indomethacin (IND) therapy for patent ductus arteriosus (PDA) in neonates with genetic disorders and/or congenital anomalies soon after birth. STUDY DESIGN: A total of 301 neonates with a genetic disorder and/or congenital anomalies and with a gestational age of ≥ 35 weeks were admitted during the study period. Eighty-five neonates with 56 genetic disorders (30 cases of trisomy 21, 10 cases of trisomy 18, and 16 others) and 29 congenital anomalies, and with clinical symptoms received intravenous IND therapy. The management methods were similar to those used for PDA in low-birth-weight infants. RESULTS: IND therapy had a clinical benefit at a high rate of 79% in these patients (90% and 70% in neonates with trisomies 21 and 18, respectively), including complete closure of the PDA in 52% of the patients. Although oliguria was observed in 43 infants (51%) and slight gastrointestinal bleeding was observed in 12 (14%), no infants had severe complications such as intracranial bleeding. CONCLUSIONS: IND therapy is an effective treatment option before considering surgery for PDA in neonates with genetic disorders and/or congenital anomalies. This therapy may reduce the difficulty of treatment in the acute stage among these neonates.

[Rice pollen asthma and pollinosis in childhood: seasonal asthma and allergic rhinoconjunctivitis during the period of rice pollen emission in the surrouding area of rice field].

Although in 1969, rice pollen was first reported as a cause of asthma, rice pollen allergy has not been studied after the first report and thus the allergic significance of rice pollen is not well recognized at present. We investigated the sensitization to various allergens and the residential areas in children with the symptoms of asthma or rhinoconjunctivitis during the first decade of August, and measured rice pollen-specific IgE antibodies. Eighty-eight children (57 boys and 31 girls, mean age 8.5+/-2.9 years) with bronchial asthma or allergic rhinitis/conjunctivitis were included in this study and divided into two groups: children with (n=21) or without (n=67) symptoms during this period. The positivity rate to orchard grass pollen and the rate of residence in the surrounding area of rice field were high (81%, P=0.008 and 86%, P<0.001, respectively) in children with allergic symptoms, as compared to the values (48% and 27%, respectively) in children without symptoms. As the rice pollen season in Nagano occurs in the first decade of August, we measured rice pollen-specific IgE antibodies in 8 patients with symptoms during this period; all of these patients showed positive IgE antibodies to rice pollen. The RAST-inhibition assay using orchard grass and rice pollen indicated cross-allergenecity between these two pollen and also the existence of rice pollen-specific allergens. These results suggest that rice pollen induces seasonal asthma and allergic rhinoconjunctivitis during the first decade of August, which is the rice pollen season, in the surrounding area of rice fields.

Role of water-soluble polysaccharides in bacterial cellulose production.

Acetobacter xylinum BPR2001 produces water-insoluble bacterial cellulose (BC) and a water-soluble polysaccharide called acetan in corn steep liquor-fructose medium. Acetobacter xylinum EP1, which is incapable of acetan production was derived by disrupting the aceA gene of BPR2001. The BC production by EP1 (2.88 g/L) was lower than that by BPR2001 (4.6 g/L) in baffled-flask culture. When purified acetan or agar was added to the medium from the start of cultivation, the BC production by EP1 was enhanced and the final BC yield of EP1 was almost the same as that of BPR2001. A similar improvement of BC production by EP1 by the addition of agar was also confirmed by cultivation in a 50-L airlift reactor. From these results, the role of acetan in BC production is associated with the increase in the viscosity of the culture medium which may hinder coagulation of BC and cells in the culture, thereby accelerating the growth of BPR2001 and BC production by BPR2001.

Effects of acetan on production of bacterial cellulose by Acetobacter xylinum.

Acetan is a water-soluble polysaccharide produced by a bacterial cellulose (BC) producer, Acetobacter xylinum. An acetan-nonproducing mutant, EP1, was generated from wild-type A. xylinum BPR2001 by the disruption of aceA, which may act to catalyze the first step of the acetan biosynthetic pathway in this bacterium. EP1 produced less BC than the wild-type strain. However, when EP1 was cultured in a medium containing acetan, BC production was stimulated and the final yield of BC was equivalent to that of BPR2001. The culture broth containing acetan was more viscous and the free cell number was higher than that of the broth without the polysaccharide, so acetan may hinder the coagulation of BC in the broth. The addition of 1.5 g/l agar also increased BC production; we concluded that acetan and BC syntheses were not directly related on the genetic level.

Novel glycosyltransferase genes involved in the acetan biosynthesis of Acetobacter xylinum.

Novel aceQ and aceR genes involved in the acetan biosynthesis of Acetobacter xylinum were newly isolated. The homology search with DNA Data Bank of Japan indicated that aceQ and aceR were glycosyltransferases. Their gene-disrupted mutants were obtained by homologous recombination using the tetracycline resistance gene and the electroporation method. By NMR and ESI-MS analyses, aceQ-disrupted mutant DQ was found to secrete a water-soluble polysaccharide harboring the -Man-GlcUA side chain and the aceR-disrupted mutant DR was found to secrete an acetan analog, lacking the terminal Rha residue. These results suggested that aceQ and aceR encode a glucosyltransferase and a rhamnosyltransferase, respectively. It was indicated that acetan analogs harboring various side chains can be generated easily by genetic engineering.