Comparison of colorimetry and electrothermal atomic absorption spectroscopy for the quantification of non-transferrin bound iron in human sera

This paper describes a comparison of two analytical techniques, one employing bathophenanthrolinedisulfonate (BPT), a most commonly-used reagent for Fe (II) determination, as chromogen and an electrothermal atomic absorption spectroscopy (ETAAS) for the quantification of non-transferrin bound iron (NTBI) in sera from thalassemic patients. Nitrilotriacetic acid (NTA) was employed as the ligand for binding iron from low molecular weight iron complexes present in the serum but without removing iron from the transferrin protein. After ultrafiltration the Fe (III)-NTA complex was then quantified by both methods. Kinetic study of the rate of the Fe (II)-BPT complex formation for various excess amounts of NTA ligand was also carried out. The kinetic data show that a minimum time duration (> 60 minutes) is necessary for complete complex formation when large excess of NTA is used. Calibration curves given by colorimetric and ETAAS methods were linear over the range of 0.15-20 microM iron (III). The colorimetric and ETAAS methods exhibited detection limit (3sigma) of 0.13 and 0.14 microM, respectively. The NTBI concentrations from 55 thalassemic serum samples measured employing BPT as chromogen were statistically compared with the results determined by ETAAS. No significant disagreement at 95% confidence level was observed. It is, therefore, possible to select any one of these two techniques for determination of NTBI in serum samples of thalassemic patients. However, the colorimetric procedure requires a longer analysis time because of a slow rate of exchange of NTA ligand with BPT, leading to the slow rate of formation of the colored complex.     

Molecular characterization and complete genome analysis of human enterovirus 71 and coxsackievirus A16 from children with hand, foot and mouth disease in Thailand during 2008-2011

Hand, foot and mouth disease (HFMD) has mostly been caused by enterovirus 71 (EV71) and coxsackievirus A16 (CA16). CA 16 was the most common cause of HFMD in 2010. EV71 had a high prevalence in 2008-2009 and has been identified with a higher frequency since 2011. Nearly complete genome sequences of three EV71 strains (2008-2009 strains) and two CA16 strains (2010 strains) obtained from outbreaks in Thailand in 2008 to 2010 were characterized. Based on a phylogenetic tree of the complete VP1 region, three EV71 strains grouped into the B5, C1 and C4 genotypes, and two CA16 strains grouped into the C genotype. Based on sequence analysis, nucleotide changes were found to cluster in the internal ribosome entry site (IRES) element of the 5′-untranslated region (5′-UTR). Amino acid differences identified in all strains were located in the non-structural protein. These data also provide the molecular epidemiology of EV71 and CA16 outbreaks in Thailand.     

Role of vitelline envelope during fertilization in the black tiger shrimp, Penaeus monodon

Animal eggs possess investments through which sperm must penetrate. The aim of the present study was to investigate the role of the egg coating, the vitelline envelope, during sperm-egg interactions in the black tiger shrimp, Penaeus monodon. The site(s) of primary binding between sperm and egg and the possible binding molecule(s) for sperm were identified. In vitro adsorption of the vitelline envelope protein onto the sperm surface showed that primary binding occurred between the sperm anterior spike of acrosome intact sperm and the vitelline envelope. Results from streptavidin blotting revealed that the component of the vitelline envelope that interacts with the sperm integral membrane protein is a 370 kDa protein. In addition, it was shown that the vitelline envelope protein had no ability to induce acrosome reaction. These results suggest that the function of the vitelline envelope is as a primary binding site for sperm in shrimp, but not a sole trigger for the acrosome reaction.     

Rabies neutralizing antibody after 2 intradermal doses on days 0 and 21 for pre-exposure prophylaxis

Pre-exposure prophylaxis is recommended for people who will be exposed to rabies virus in the laboratory or who will contact with mammals. World Health Organization recommends 2 doses of a cell-culture rabies vaccine given 1 week apart, and a third booster dose given 2–3 weeks later. Neutralizing antibody response is virtually 100%, and the individual remains sensitized indefinitely. Intradermal pre-exposure regimen for rabies prophylaxis is more economical compared with the conventional intramuscular regimen in terms of vaccine volume. However, both regimens require three clinic visits. In order to reduce non-medical expenses such as transportation to the clinics and to increase compliance, the immunogenicity and safety of two-visit intradermal regimen for pre-exposure prophylaxis were studied. Fifty-five healthy subjects aged between 18 and 24 years were enrolled and divided into two groups. Group A (n = 39) received 0.1 ml of purified Vero cell rabies vaccine (PVRV; Sanofi Pasteur, Lyon, France; Lot no. Z0996 with an antigenic value of 4.8 IU/0.5 ml vial) intradermally each at two sites on days 0 and 21. Group B (n = 16) received 0.5 ml of PVRV intramuscularly on days 0, 7 and 21, as conventional intramuscular regimen for pre-exposure prophylaxis. Rabies neutralizing antibody (Nab) titers were measured on days 0, 35, 365 and 379 (14 days after simulated post-exposure booster vaccination). All subjects from two groups had Nab titers ≥0.5 IU/ml on day 35. In addition, the difference between geometric mean titers for group A (4.51 IU/ml; range of Nab titers 1.69–13.0 IU/ml) and group B (6.74 IU/ml; range of Nab titers 2.20–14.23 IU/ml) on day 35 was not statistically significant (p > 0.05). One year after pre-exposure vaccination, all subjects in both groups received simulated post-exposure booster vaccination with 0.1 ml of PVRV ID on days 0 and 3 (day 365 and day 368 after pre-exposure vaccination). After simulated booster vaccinations with 0.1 ml PVRV ID on days 0 and 3, all subjects in groups A (GMT 14.38 IU/ml; range 2.99–308.44 IU/ml) and in group B (GMT 14.06 IU/ml; range 3.12–62.09 IU/ml) had rabies Nab titers ≥0.5 IU/ml on day 14 post-booster (p > 0.05). Mild local adverse events such as pain at injection site, pruritus and erythema were observed. Our study indicated that 2-site intradermal pre-exposure regimen on days 0 and 21 with 0.1 ml of cell-culture rabies vaccine is safe and immunogenic as the conventional intramuscular regimen.     

Rabies Exposure Risk among Foreign Backpackers in Southeast Asia

Rabies remains a problem in Southeast Asia where large numbers of backpackers visit each year. During May–June 2008, a survey study was conducted of foreign backpackers in Bangkok, Thailand to assess their risk of rabies exposure. Eight hundred seventy (870) questionnaires were collected and analyzed. The median age of the backpackers was 25.5 years. Most of them were European (68.4%), followed by North American (13.2%). Although 80.7% had sought health information before traveling, only 55.6% had received information about rabies. Only 18.1% had completed pre-exposure rabies vaccination (3 shots) before travel, whereas 70.9% had not been vaccinated for rabies at all. In this study, the incidence of being licked was 3.56%, and of being bitten 0.69%, on average stays of 30.06 days in Southeast Asia. More than a half (54%) of exposures occurred in the first 10 days after arrival in Southeast Asia.     

The presence and distribution of gonadotropin-releasing hormone-liked factor in the central nervous system of the black tiger shrimp, Penaeus monodon

The distribution and presence of gonadotropin-releasing hormone (GnRH) in the central nervous system (CNS) of Penaeus monodon were examined by immunocytochemistry, high performance liquid chromatography (HPLC), and radioimmunoassay (RIA). We demonstrated the existence of octopus (oct)GnRH-liked immunoreactivity (ir-octGnRH) and lamprey (l)GnRH-III-liked immunoreactivity (ir-lGnRH-III) in cell bodies of medium-sized neurons of the anterior part (protocerebrum) of the supraesophageal ganglion (brain). In addition, only the ir-octGnRH was detected in the nerve fibers located in the brain and segmental ganglia (subesophageal, thoracic, and abdominal ganglia). Moreover, some branches of these fibers also innervated the neurons in the middle (deutrocerebrum), posterior (tritocerebrum) brain and segmental ganglia. There was no ir-lGnRH-I and ir-salmon (s)GnRH detected in the shrimp CNS. The results from HPLC and RIA showed ir-GnRH in the CNS using anti-lGnRH-III, but not with anti-mammalian (m)GnRH. The data from immunocytochemistry, HPLC and RIA suggest that ir-GnRH in shrimp may be more similar to octGnRH and lGnRH-III than the other forms. These findings support the hypothesis that GnRH-liked factor(s) may be an ancient peptide that also exists in this decapod crustacean.     

Chlamydophila pneumoniae infection among young children with respiratory diseases in Thailand

A total of 136 children aged 5 years and under with respiratory tract diseases were examined for Chlamydophila pneumoniae infection. By means of the micro-immunofluorescence test, an acute infection was suggested in 37 (27.2%) of them. Infection was found in 23 (43.4%) of 53 children with bronchitis, seven (70.0%) of 10 with pharyngitis, and two (22.2%) of nine with pneumonia. C. pneumoniae DNA was detected in seven of 55 children by means of nasopharyngeal swabs, and serological evidence was present in all of seven. Five of them were suggested the acute infection and four of the five showed IgG titers increasing four times and over. By age distribution, five of the seven DNA-positive children were 1 year old, and the remaining two were 2 and 4 years old, respectively. The clinical findings of the seven DNA-positive children were characterized as indicative of bronchitis (n = 4), pharyngitis (n = 2), and pneumonia (n = 1). In Thailand, C. pneumoniae infection occurs frequently among children aged 5 years and under, and may cause pharyngitis, bronchitis, and sometimes pneumonia. However, it is suggested that C. pneumoniae infection is not a major cause of severe pneumonia among children in that age group.