Oxidative DNA damage and repair in children exposed to low levels of arsenic in utero and during early childhood: Application of salivary and urinary biomarkers

The present study aimed to assess arsenic exposure and its effect on oxidative DNA damage and repair in young children exposed in utero and continued to live in arsenic-contaminated areas. To address the need for biological specimens that can be acquired with minimal discomfort to children, we used non-invasive urinary and salivary-based assays for assessing arsenic exposure and early biological effects that have potentially serious health implications. Levels of arsenic in nails showed the greatest magnitude of difference between exposed and control groups, followed by arsenic concentrations in saliva and urine. Arsenic levels in saliva showed significant positive correlations with other biomarkers of arsenic exposure, including arsenic accumulation in nails (r = 0.56, P < 0.001) and arsenic concentration in urine (r = 0.50, P < 0.05). Exposed children had a significant reduction in arsenic methylation capacity indicated by decreased primary methylation index and secondary methylation index in both urine and saliva samples. Levels of salivary 8-OHdG in exposed children were significantly higher (~ 4-fold, P < 0.01), whereas levels of urinary 8-OHdG excretion and salivary hOGG1 expression were significantly lower in exposed children (~ 3-fold, P < 0.05), suggesting a defect in hOGG1 that resulted in ineffective cleavage of 8-OHdG. Multiple regression analysis results showed that levels of inorganic arsenic (iAs) in saliva and urine had a significant positive association with salivary 8-OHdG and a significant negative association with salivary hOGG1 expression.     

Oxidative DNA damage and inflammatory responses in cultured human cells and in humans exposed to traffic-related particles

Particulate pollution is a major public health concern because epidemiological studies have demonstrated that exposure to particles is associated with respiratory diseases and lung cancer. Diesel exhaust particles (DEP), which is classified as a human carcinogen (IARC, 2012), are considered a major contributor to traffic-related particulate matter (PM) in urban areas. DEP consists of various compounds, including PAHs and metals which are the principal components that contribute to the toxicity of PM. The present study aimed to investigate effects of PM on induction of oxidative DNA damage and inflammation by using lymphocytes in vitro and in human exposed to PM in the environment. Human lymphoblasts (RPMI 1788) were treated with DEP (SRM 2975) at various concentrations (25–100 μg/ml) to compare the extent of responses with alveolar epithelial cells (A549). ROS generation was determined in each cell cycle phase of DEP-treated cells in order to investigate the influence of the cell cycle stage on induction of oxidative stress. The oxidative DNA damage was determined by measurement of 8-hydroxy-deoxyguanosine (8-OHdG) whereas the inflammatory responses were determined by mRNA expression of interleukin-6 and -8 (IL-6 and IL-8), Clara cell protein (CC16), and lung surfactant protein-A (SP-A). The results showed that RPMI 1788 and A549 cells had a similar pattern of dose-dependent responses to DEP in terms of particle uptake, ROS generation with highest level found in G2/M phase, 8-OHdG formation, and induction of IL-6 and IL-8 expression. The human study was conducted in 51 healthy subjects residing in traffic-congested areas. The effects of exposure to PM_2.5 and particle-bound PAHs and toxic metals on the levels of 8-OHdG in lymphocyte DNA, IL-8 expression in lymphocytes, and serum CC16 were evaluated. 8-OHdG levels correlated with the exposure levels of PM_2.5 (P < 0.01) and PAHs (P < 0.05), but this was not the case with IL-8. Serum CC16 showed significantly negative correlations with B[a]P equivalent (P < 0.05) levels, but positive correlation with Pb (P < 0.05). In conclusion, a similar pattern of the dose-dependent responses to DEP in the lymphoblasts and lung cells suggests that circulating lymphocytes could be used as a surrogate for assessing PM-induced oxidative DNA damage and inflammatory responses in the lung. Human exposure to PM leads to oxidative DNA damage whereas PM-induced inflammation was not conclusive and should be further investigated.     

Single-dose therapy for giardiasis in school-age children

A randomized controlled trial was carried out to study the efficacy of combined albendazole and praziquantel in the treatment of giardiasis in school-age children. Eighty-four children were randomly allocated to 3 groups: group 1 (n = 31) albendazole 400 mg combined with praziquantel 20 mg/kg; group 2 (n = 26) albendazole 800 mg as a single dose; group 3 (n = 27) tinidazole 50 mg/kg as a single dose. The treatment was considered curative when Giardia was not found in two consecutive stool samples. The parasitological cure rate was 74.2% for combined single-dose albendazole-praziquantel, 50% and 92.6% in the albendazole and tinidazole groups respectively (p = 0.0023). There was no statistically significant difference between the cure rates of the combined regimen and tinidazole (p > 0.05). This combined regimen was considered safe, with only minor side-effects being observed. Of the single-dose regimens, tinidazole still achieves the highest parasitological cure rate for giardiasis. The albendazole-praziquantel combined regimen may be an alternative single-dose therapy for giardiasis in children, especially as this combination will eradicate common intestinal protozoa and co-existing helminths. Whether the dosage of this combination treatment should be adjusted for G. intestinalis remains to be established by further study.     

Emergence and properties of fluoroquinolone resistant Salmonella enterica serovar Typhi strains isolated from Nepal in 2002 and 2003

A total of 171 Salmonella enterica serovar Typhi strains isolated from Nepal, mostly from patients with typhoid fever in 2002-2003, were tested for antimicrobial susceptibility by disk diffusion assay. Selected S. enterica serovar Typhi isolates were tested for MICs by E-test for ceftriaxone, ciprofloxacin and ofloxacin. Mutations of DNA gyrase gyrA and gyrB and topoisomerase IV parC and parE were identified by sequencing of PCR amplicons. By disk diffusion assay, 75/171 S. enterica serovar Typhi isolates were resistant to nalidixic acid, ampicillin, choramphenicol, streptomycin, tetracycline, sulfisoxazole, and trimethroprim/sulfamethoxazoles. Multiple drug resistance to the 7 antimicrobials was most predominant among S. enterica serovar Typhi isolates in this study. Resistance to nalidixic acid was detected in 76/111 and 56/60 of total isolates collected in 2002 and 2003, respectively. Nalidixic acid-resistant isolates in 2002 and 2003 showed MIC range for ciprofloxacin of 0.125-0.250 mg/l. Nalidixic acid-resistant isolates contained point mutations in gyrA and parC but not gyrB and parE. The gyrA mutation of nalidixic acid-resistant isolates obtained in 2002 and 2003 had amino acid substitution at position 83 of Serine-->Tyrosine and Serine-->Phenylalanine, respectively. Two different mutations of gyrA were detected among nalidixic acid-resistant isolates. Thus it is necessary to monitor mutation in DNA topoisomerase associated with increases in quinolones resistance.     

Surgical outcome of intravitreal bevacizumab and filtration surgery in neovascular glaucoma

INTRODUCTION: The purpose of this study was to evaluate the surgical outcome of a trabeculectomy with mitomycin C (MMC) in neovascular glaucoma after an adjunctive treatment with intravitreal bevacizumab (Avastin(R); Genentech Inc, San Francisco, CA, USA) injection (IVB). METHODS: Six patients with NVG presented at the Department of Ophthalmology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Thailand. After adequate panretinal photocoagulation (PRP) and maximal antiglaucoma medication therapy, these patients received IVB (1.25 mg in 0.05 ml) due to persistent neovascularisation of the iris (NVI). A fornix-based conjunctival flap trabeculectomy with MMC was performed within 4 weeks following administration of IVB. RESULTS: Three patients with proliferative diabetic retinopathy (PDR) and three patients with central retinal vein occlusion (CRVO) were enrolled in the study (mean age, 57 years). Absolute regression of NVI was observed within 1 week after IVB in four patients. In two patients NVI was reduced but still persisted. Mean intraocular pressure (IOP) decreased from 39.8 mmHg pre-operatively to 7.5 mmHg on the first postoperative day. No intra-operative complications were noted. Two patients had postoperative hyphema, which resolved spontaneously within 1 week. During the mean follow up of 24.7 weeks, five patients had controlled IOP (range, 2-16 mmHg) without antiglaucoma medication. Two patients with PDR had improved visual acuity whereas two patients with CRVO lost pre-operative light perception. Recurrent NVI was subsequently detected in one patient who had uncontrolled IOP. This patient underwent transscleral diode laser cyclophotocoagulation and additional PRP. All patients were symptom-free at last visit. CONCLUSION: IVB is an effective modality to reduce intra-operative complications during trabeculectomy for neovascular glaucoma. The short-term outcomes following trabeculectomy with MMC are favourable.     

Increased health risk in Bangkok children exposed to polycyclic aromatic hydrocarbons from traffic-related sources

The aim of this study is to assess potential health risk of exposure to particle-associated polycyclic aromatic hydrocarbons (PAHs) in children living in a megacity with traffic congestion such as Bangkok. The study population comprised 184 Thai schoolboys (aged 8-13 years) attending schools adjacent to high-density traffic areas in Bangkok and schools located in the provincial area of Chonburi. The ambient concentration of total PAHs at roadsides in proximity to the Bangkok schools was 30-fold greater than at roadsides in proximity to the provincial schools (30.39 +/- 5.80 versus 1.50 +/- 0.28 ng/m(3); P < 0.001). Benzo(g,h,i)perylene (BghiP), an indicator of automobile exhaust emission, was the predominant PAH. Personal exposure to total PAHs and the corresponding benzo(a)pyrene (BaP) equivalent concentrations in Bangkok schoolchildren were 3.5-fold higher than in provincial schoolchildren (4.13 +/- 0.21 versus 1.18 +/- 0.09 ng/m(3); P < 0.001 and 1.50 +/- 0.12 versus 0.43 +/- 0.05 ng/m(3); P < 0.001, respectively). The concentration of urinary 1-hydroxypyrene (1-HOP) was significantly higher in Bangkok schoolchildren. Bulky carcinogen-DNA adduct levels in peripheral lymphocytes were also significantly higher (0.45 +/- 0.03 versus 0.09 +/- 0.00 adducts/10(8) nt; P < 0.001). Finally, a significantly higher level of DNA strand breaks and a significantly lower level of DNA repair capacity were observed in Bangkok schoolchildren (P < 0.001). This study indicates that Bangkok schoolchildren exposed to a high level of genotoxic PAHs in ambient air may be more vulnerable to the health impacts associated with the exposure to genotoxic pollutants than children in provincial areas and may have increased health risks for the development of certain diseases such as cancer.