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.     

Occupational health and safety situation and research priority in Thailand

The aims of this article are to review the situation of occupational health and safety and to describe research priority in this field in Thailand. Thailand is one of newly industrialized countries in Southeast Asia. Approximately half of the working population is still in agriculture. The data from Thai Workmen's Compensation Fund showed that incidence rate of occupational injuries and diseases was 3-4% each year. Almost were occupational injuries from various accidents in workplaces. At least 3 relevant governmental agencies, including Ministry of Labour, Ministry of Public Health, and Ministry of Industry, are responsible in occupational health and safety in the country. Nowadays, those agencies collaborate and develop projects and activities to prevent and control of the problems. Because of lack of staff and other resources, research priority is needed and has been developed recently. The framework of research needed focuses on research and development such as how to improve occupational health and safety management at all levels, setting up and development of standard guidelines for health and environmental assessment, and implementation of suitable control measures in workplaces. Finally, improvement of research system in the country is essential to cope with new occupational health problems in the near future.     

Reactogenicity and immunogenicity of reduced antigen content diphtheria-tetanus-acellular pertussis vaccine (dTpa) administered as a booster to 4-6 year-old children primed with four doses of whole-cell pertussis vaccine

A trial to compare the reactogenicity and immunogenicity of a reduced antigen content diphtheria-tetanus-acellular pertussis (dTpa) vaccine with diphtheria-tetanus-whole-cell pertussis (DTPw) vaccine was conducted in Thailand. Three hundred and thirty children aged 4-6 years, primed with four doses of DTPw, received a single injection of either dTpa or DTPw. There was a significantly lower incidence of local and general reactions following dTpa than DTPw (P<0.001). One month after vaccination, 99.4 and 100% of all subjects had protective anti-diphtheria and -tetanus titers, respectively. The vaccine response rate to pertussis antigens was similar in both groups, with 96.9% versus 92.5% for anti-pertussis toxin (PT), 96.9% versus 97.5% for anti-filamentous hemagglutinin (FHA) and 95.1% versus 90.8% for anti-pertactin (PRN) in the dTpa and DTPw groups, respectively. For anti-BPT, the vaccine response in the dTpa group was 29.6% versus 94.4% for DTPw. In conclusion, the dTpa vaccine was as immunogenic and significantly better tolerated than DTPw. The new dTpa vaccine could improve coverage for routine booster vaccination in children and provide a good replacement for DTP vaccines at 4-6 years of age.     

Evaluation of proinflammatory cytokine production induced by linear and branched polyethylenimine/plasmid DNA complexes in mice

The purpose of this study was to evaluate the cytokine response induced by linear and branched polyethylenimine (PEI)/plasmid DNA (pDNA) complex (polyplex) in relation to the ratio of PEI nitrogen and DNA phosphate (N/P ratio) of the polyplex, dose of pDNA, and structure and molecular weight of PEI, which are important for transfection efficacy of PEI polyplex. As a control, a N-[1-(2, 3-dioleyloxy) propyl]-n,n,n-trimethylammonium chloride/cholesterol liposome/pDNA complex (lipoplex) was selected for its high transfection efficacy in vivo. The concentration of proinflammatory cytokines such as tumor necrosis factor (TNF)-alpha were much lower after the administration of polyplex than lipoplex irrespective of the N/P ratio, dose of pDNA, or structure and molecular weight of PEI, although these factors affected the transfection efficacy in vivo. We demonstrated that the amount of activated nuclear factor-kappaB, which contributes substantially to the production of cytokines, was comparable with the control (no treatment) level, and significantly less than that obtained with lipoplex. Although the production of proinflammatory cytokines (TNF-alpha, interferon-gamma, and interleukin-12) was reduced on the administration of the linear PEI polyplex, serum alanine aminotransferase levels were significantly enhanced by pDNA in a dose-dependent manner, suggesting that such hepatic damage is not induced by proinflammatory cytokines.     

Detection of heterogeneous, intermediate-vancomycin-resistant Staphylococcus aureus (hVISA) using low-concentration vancomycin disks

Heterogeneous, intermediate-vancomycin-resistant Staphylococcus aureus (hVISA) represents a threat of an incurable infection since the first report in 1997. The method used to detect hVISA isolates is a population analysis profile (PAP); however, it is impractical for routine laboratory analysis. We therefore tested a simple, reliable and inexpensive method for the detection of hVISA. Eighteen isolates of hVISA and 22 of vancomycin-sensitive S. aureus (VSSA) were included. The organisms were tested by the disk diffusion method, using 15-microg vancomycin disks on four different media: Mueller-Hinton agar (MHA), MHA plus 2% NaCI (MHAS), Brain Heart Infusion agar (BHA), and BHA plus 2% NaCl (BHAS). In addition, two different inoculum sizes, bacterial suspensions adjusted to 0.5 and 2.0 McFarland, were tested. The inhibition zone was read independently by three medical technologists after incubation at 37 degrees C for 24 and 48 hours. The use of MHAS with an inoculum size of 2.0 McFarland and 48-hour incubation period yielded the highest sensitivity (94.4%), specificity (81.8%), positive predictive value (80.9%), and negative predictive value (94.7%). The disk diffusion test with 15-microg vancomycin disk is simple and may be used as a screening method for the detection of hVISA.     

Development of a community participation program for diabetes mellitus prevention in a primary care unit, Thailand

The purpose of this study was to create and test a prevention model for diabetes mellitus in a primary care unit in Thailand. This study used a three-stage approach: a situational analysis was conducted by a focus group discussion, a model was developed in a brainstorming session with stakeholders, and the model was tested by community participation. Qualitative and quantitative methods were used to collect and analyze the data. The focus group discussion found that co-operation between health volunteers and primary care unit personnel in relation to diabetes screening, as well as defining the role of nurse practitioners who provide diabetic treatment, was important. The proactive model that was used for preventing diabetes mellitus was a health promotion program. It was trialed with 160 persons with prediabetes for 3 months. After the intervention, the mean score for exercise activity among the persons with prediabetes was significantly higher, while the mean score of the Body Mass Index, waist circumference, and systolic blood pressure were significantly lower than before the intervention. This meant that community participation provided proactive services to Thai persons with prediabetes.     

Anti-tumor Effect of All-<Emphasis Type="BoldItalic">Trans</Emphasis> Retinoic Acid Loaded Polymeric Micelles in Solid Tumor Bearing Mice

Purpose All-trans retinoic acid (ATRA) polymeric micelles were developed for parenteral administration. The distribution characteristics and antitumor activities of ATRA polymeric micelles were evaluated after intravenous administration to mice bearing CT26 solid tumors. Methods ATRA incorporated in poly(ethylene glycol)-poly(benzyl aspartate) block copolymer was prepared by the evaporation method. The levels of [³H]ATRA in blood and tissue including tumor were determined by measuring the radioactivity after injection into mice. The tumor volume and the survival of the mice were determined to assess the anticancer activity. Results The delivery of ATRA by polymeric micelles prolonged the blood circulation and enhanced the accumulation of ATRA in the tumor tissue compared with the administration of free ATRA. Tumor growth was significantly delayed and the survival time of mice was prolonged following the treatment by ATRA polymeric micelles demonstrating the improved anticancer activity of ATRA. Conclusion Polymeric micelles are a promising and effective carrier of ATRA in order to enhance tumor delivery and they have a promising potential application in the treatment of solid tumors.     

Primary vaccination with a new heptavalent DTPw-HBV/Hib-Neisseria meningitidis serogroups A and C combined vaccine is well tolerated.

OBJECTIVE: Safety and reactogenicity of a new heptavalent DTPw-HBV/Hib-MenAC (diphtheria, tetanus, whole cell pertussis-hepatitis B virus/Haemophilus influenzae type b-Neisseria meningitidis serogroups A and C) vaccine was compared with a widely used pentavalent DTPw-HBV/Hib vaccine. METHODS: Three phase III randomized studies comparable in design and methodology, in which healthy infants received DTPw-HBV/Hib-MenAC (N=1334) or DTPw-HBV/Hib (N=446) at 2, 4, and 6 months, were pooled for analysis. Solicited symptoms were recorded for 4 days, and unsolicited adverse events for 31 days after each dose. Serious adverse events (SAEs) were recorded throughout the studies. RESULTS: There were no significant differences between the two groups in the proportion of subjects with fever >39.5 degrees C or >40.0 degrees C (p<0.005). Compared to group DTPw-HBV/Hib, a significantly higher percentage of subjects in group DTPw-HBV/Hib-MenAC reported fever >39 degrees C (21.2% vs. 14.8%, p=0.004). Fever subsided quickly, did not lead to differences in attendance to medical services and did not increase from dose to dose. Sixty-seven SAEs were reported, 56/1334 (4.2%) in group DTPw-HBV/Hib-MenAC and 11/446 (2.5%) in the DTPw-HBV/Hib group. CONCLUSION: Overall, the heptavalent and pentavalent vaccines had similar safety profiles. The difference observed in percentage of subjects with fever >39 degrees C did not lead to differences in medically attended visits for fever.     

Labile plasma iron (LPI) as an indicator of chelatable plasma redox activity in iron-overloaded beta-thalassemia/HbE patients treated with an oral chelator

Persistent levels of plasma nontransferrin bound iron (NTBI) have been associated with tissue iron overload and toxicity. We characterized NTBI's susceptibility to deferoxamine (directly chelatable iron [DCI]) and redox activity (labile plasma iron [LPI]) during the course of long-term, continuous L1 (deferiprone) treatment of patients with hemoglobin E disease and beta-thalassemia (n = 17). In 97% of serum samples (n = 267), the LPI levels were more than 0.4 microM (mean +/- SEM, 3.1 +/- 0.2 microM) and the percent transferrin (Tf) saturation more than 85 (111 +/- 6), whereas only in 4% of sera were the LPI levels more than 0.4 microM for Tf saturation less than 85%. Daily administration of L1 (50 mg/kg) for 13 to 17 months caused both LPI and DCI to decrease from respective initial 5.1 +/- 0.5 and 5.4 +/- 0.6 microM to steady mean levels of 2.18 +/- 0.24 and 2.81 +/- 0.14 microM. The steady lowest levels of LPI and DCI were attained after 6 to 8 months, with a half time (t(1/2)) of 2 to 3 months. Serum ferritin and red cell membrane-associated iron followed a similar course but attained steady basal levels only after 10 to 12 months of continuous treatment, with a t(1/2) of 5 to 7 months. These studies indicate that LPI and DCI can serve as early indicators of iron overload and as measures for the effectiveness of iron chelation in reducing potentially toxic iron in the plasma.     

Clinical trial of deferiprone iron chelation therapy in beta-thalassaemia/haemoglobin E patients in Thailand

Nine patients with either beta-thalassaemia/haemoglobin E (7) or homozygous beta-thalassaemia (2) not requiring regular transfusions were treated with the oral iron chelator, deferiprone 25-50 mg/kg/d for between 17 and 86 weeks (mean 49 weeks). There were significant decreases in serum ferritin (initial mean +/- standard deviation 2168 +/- 1142, final 418 +/- 247 micro g/l; t-test for paired samples, P = 0.005), hepatic iron (initial 20.3 +/- 6.26, final 11.7 +/- 4.83 mg/g/dry weight; P = < 0.02), red cell membrane iron (initial 76.2 +/- 3.64, final 7.2 +/- 0.56 mmol/mg protein; P = < 0.0005) and serum non-transferrin bound iron (initial 9.0 +/- 0.56, final 5.9 +/- 0.89 micro mol/l; P = < 0.0005). There was also a significant rise in serum erythropoietin (initial 240 +/- 195.1, final 433.2 +/- 269.2 U/l; P = 0.034). The haemoglobin level rose in three patients and transfusion requirements were reduced substantially in four patients. Serum thiobarbituric acid reactive substance (TBARS) also fell in six of eight patients. Patients generally improved clinically, with weight gain observed. Side-effects were mild and included gastrointestinal symptoms (6) and arthralgia (1), not requiring withdrawal of the drug. One patient died at 17 weeks of therapy as a result of an intercurrent infection. His neutrophil count was normal. We conclude that deferiprone is an effective, well-tolerated iron chelator for patients with thalassaemia intermedia. Further studies are needed to determine the optimum dose and length of treatment needed to reduce iron burden to a safe level in these patients.