Effects of oxidative stress and NF-κB levels in peripheral blood mononuclear cells on development of silicosis

Objective To investigate the change of indicators of oxidative stress in serum and NF-κB in peripheral blood mononuclear cells of patients with silicosis, and explore the mechanism of the development of silicosis. Methods The subjects were divided into (1) 200 workers exposed to SiO2 for at least 1 years in a foundry served as the dust-exposure group; (2) 130 cases with silicosis (Ⅰ phase silicosis 64 cases, Ⅱ phase 46 cases Ⅲ phase 20 cases) served as the silicosis goup; (3) 32 cases with 0+ phase silicosis in the foundry served as the observed group,(4)100 subjects from a hotel served as the control group. The serum including superoxide dismutase (SOD), nitric oxide (NO), serum glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), nitric oxide synthase (NOS), lipid malondialdehyde (MDA) and NF-κB protein levels in peripheral blood mononuclear cells were determined, respectively. Results Compared with the control group,NO levels in dust-exposed group and silicosis group significantly increased, and SOD decreased significantly (P＜0.05 or P＜0.01). Compared with the control group and dust-exposed group, T-AOC, NOS, MDA levels in silicosis group significantly increased (P＜0.05 or P＜0.01). GSH-Px in dust-exposed group and silicosis group were (231.164±36.484) and (270.469±39.228)U/md, respectively which were significantly than that [(223.360±46.838) U/ml] in control group (P＜0.05 or P＜0.01), and there was significant difference of GSHPx between the silicosis group and the dust-exposed group significantly (P＜0.01). GSH-Px level [(290.750±39.129) U/ml] in Ⅲ phase silicosis group were significantly higher than those [(256.906±21.41) and (259.594±34.79) U/ml] in observation group and Ⅰ phase silicosis group (P＜0.05). NF-κB levels [(72.06±9.12) and (85.25±11.64) ng/L] in dust-exposed group and silicosis group were significantly higher than that [(59.71±9.27) ng/L] in control group (P＜0.01), and there was significant difference of between the silicosis group and the dust-exposed group (P＜0.01). There was a positive correlation between serum GSH-Px level and the silicosis stages (r=0.507,P＜0.0l). Also there was a positive correlation between NF-κB level and silicosis stages, age, GSH-Px or NO levels (r=0.376, 0.243, 0.233, 0.221, P＜0.01). Conclusion The imbalance of oxidative and anti-oxidation system and the activation of NF-κB are related with the occurrence and development of silicosis. The monitoring of oxidative stress indicators and NF-κB is beneficial to the prediction and prognosis assessment of silicosis.     

Effects of natural eggshell membrane (NEM) on cytokine production in cultures of peripheral blood mononuclear cells: increased suppression of tumor necrosis factor-α levels after in vitro digestion

Tumor necrosis factor-α (TNF-α) plays an important role in inflammatory processes. This study examined the effects of natural eggshell membrane (NEM(?)) (ESM Technologies, LLC, Carthage, MO, USA) on interleukin (IL)-2, IL-4, IL-6, IL-10, interferon-γ (IFN-γ), and TNF-α cytokine production by 4-day peripheral blood mononuclear cell (PBMC) cultures exposed to serial dilutions of either an aqueous extract of natural eggshell membrane (NEM-AQ) or NEM subjected to in vitro digestion (NEM-IVD). The effects on cytokine production were also assessed in the presence of phytohemagglutinin (PHA) and pokeweed mitogen (PWM) where exposure to NEM-AQ resulted in reduced levels of proliferation and statistically significant effects on IL-6, IL-10, IFN-γ, and TNF-α cytokine production. NEM-AQ reduced levels of IL-6, IL-10, IFN-γ, and TNF-α in cultures exposed to PHA. In cultures containing PWM, NEM-AQ reduced production of IL-10 and at the highest dose tested increased IL-6 and decreased TNF-α cytokine levels. NEM-IVD, at the two lowest concentrations of product, significantly reduced TNF-α production by PBMC cultures exposed to PWM compared with the in vitro digest control or native NEM. Taken together, these results suggest that NEM-AQ can influence signaling events in response to the T cell-specific mitogen PHA as well as to the mitogen PWM that require cellular cross-talk and that these effects may be partially mediated through a reduction in level of the pro-inflammatory cytokine TNF-α. The suppression of TNF-α production in the presence of NEM-IVD is promising for the use of NEM as a consumable anti-inflammatory product.     

Attenuating characteristics of DEN-2 PDK53 in flavivirus-naïve peripheral blood mononuclear cells

A live-attenuated DEN-2 virus, DEN-2 strain 16681-PDK53, has been found to be attenuated for both humans and mice with an unknown mechanism. To partially answer this question, responses of flavivirus-na?ve primary human PBMC to infection with attenuated DEN-2 PDK53 (D2/IC-VV45R) virus and its parental, virulent DEN-2 16681 virus (D2/IC-30P-A) were investigated at the cellular and genetic levels using cDNA array analysis. Both DEN-2 viruses produced similar replication kinetics in flavivirus-na?ve PBMC. In contrast, virulent DEN-2 virus caused a higher percentage of apoptotic death. A macro-array analysis showed that the virulent D2/IC-30P-A virus induced changes in the expression of a greater number of genes than did the attenuated D2/IC-VV45R virus, 31 genes versus 19 genes, respectively, by 24 h post-infection. Interestingly, both viruses stimulated cytokines known to be virulence factors for DEN virus infection, such as IL-1beta, IL-6, IL-8, IL-10, MIP-1beta, and MIP-1alpha. The virulent virus additionally up-regulates immune suppression factors and down-regulates immune activator and growth factors. In conclusion, our data demonstrated that D2-PDK53 effected less change in PBMC than D2-16681 in terms of observable cellular effect and expression of cytokine and chemokine related genes.     

Epidemiological distribution of hepatitis B virus genotypes in 1–29-year-olds in the mainland of China

BackgroundTo analyze the epidemiological distribution of Hepatitis B virus (HBV) genotype in the mainland of China following the implementation of effective preventive measures.MethodsFive hundred and seventeen HBsAg-positive subjects aged 1–29 years surveyed in the 2014 national HBV sero-survey in the mainland of China were enrolled in the study. The full-length HBV genome was obtained by PCR amplification and sequencing. The HBV genotype was determined by phylogenetic analysis. Combined with questionnaire information, HBV genotype distribution was analyzed.ResultsOf the 517 HBsAg-positive subjects, 369 (71.4%) were included in the analysis. HBV genotypes found were B (45.0%), C (36.6%), D (6.0%), C/D (9.8%), B/C (2.2%), and I (0.5%). Geographic differences in HBV genotype were significant for seven regions. Three serotypes were found: adw (47.2%), adr (35.5%), and ayw (17.3%). B2 (43.9%) and C2 (25.2%) were the two major subgenotypes. The predominant genotypes differed between the Han group and the other ethnic groups. No statistical differences in genotype distribution were found by gender, age group, or hepatitis B (HepB) vaccination history.ConclusionThe prevalence of HBV genotype B was higher than that of genotype C with subgenotypes B2 and C2 endemic in 1–29-year-olds in the mainland of China, after HBV prevalence has reduced significantly due to the implementation of preventive measures. HepB vaccination or other factors did not interfere with HBV genotype distribution. The surveillance of HBV genotype was essential for responding to the potential changes and impact on the preventive policies in the future.     

Influence of Cooking and Heating Fuel Use on 1–59 Month Old Mortality in South Africa

Objectives: To determine the association between the combustion of wood, animal dung, coal and paraffin (polluting fuels) for cooking and heating and 1–59 month old mortality in South Africa, whilst adjusting for a number of confounders. Methods: Data from 3,556 children (142 deaths) living in 2,828 households were extracted from the 1998 South African Demographic and Health Survey (SADHS) database. The SADHS was the first national health survey conducted across the entire country and provided the opportunity to examine the prevalence and determinants of various morbidity and mortality outcomes in a representative national population. Results: The results suggest that exposure to cooking and heating smoke from polluting fuels is significantly associated with 1–59 month mortality, after controlling for mother's age at birth, water source, asset index and household crowdedness (RR=1.95; 95% CI=1.04, 3.68). Conclusions: Although there is potential for residual confounding despite adjustment, the better documented evidence on outdoor air pollution and mortality suggest this association may be real. As nearly half of households in South Africa still rely on polluting fuels and women of childbearing age perform most cooking tasks, the attributable risk arising from this association, if confirmed, could be substantial. It is trusted that more detailed analytical intervention studies will scrutinise these results in order to develop integrated intervention programmes to reduce children's exposure to air pollution emanating from cooking and heating fuels.     

A Mediterranean dietary style influences TNF–alpha and VCAM–1 coronary blood levels in unstable angina patients

Summary Background A Mediterranean dietary pattern has been associated with a reduced risk of coronary heart disease, as well as a reduction of oxidative stress, but studies indicating possible interactions between food intake and inflammatory mediators production at specific sites are lacking. Aim of the study To assess the relationship between Mediterranean diet consumption and inflammatory related molecules production in coronary vessels. Methods A previously reported Mediterranean–diet score was computed summing–up the quintiles of eight dietary components from a validated food frequency questionnaire in 24 patients with unstable angina. Tumor necrosis factor (TNF–α) and vascular cell adhesion molecule (VCAM–1) concentrations were measured in coronary sinus blood. Results Both biomarkers showed an inverse association with the Mediterraneandiet score. The association between VCAM–1 and the Mediterranean–diet score had an adjusted β coefficient of –35.1 ng/ml (95% coefficient interval, CI: –63.5 to –6.7). The adjusted β coefficient using TNF–α as the dependent variable was –41.6 pg/ml (95 % CI: –76.2 to –7.1). The consumption of olive oil as a single item showed a significant inverse association, and a Mediterranean–diet score excluding olive oil was also inversely associated with TNF–α and VCAM–1 serum levels in coronary venous blood. Conclusions Adherence to a Mediterranean dietary pattern may protect against coronary artery wall production of inflammatory mediators. This finding could provide a novel mechanistic explanation for the recognized lower coronary risk associated with a Mediterranean diet.     

The effect of different warming methods on sensory nerve conduction velocity in shipyard workers occupationally exposed to hand–arm vibration

OBJECTIVES: Segmental sensory nerve conduction velocity (SNCV) was measured from the wrists to the hands and digits in a population of 134 (126 men and 8 women) vibration-exposed shipyard workers following systemic warming using a bicycle ergometer. Results were compared to earlier nerve conduction tests, identical in execution, except that the warming process was segmental and cutaneous. The study was designed to investigate whether SNCVs, which were selectively slow in the fingers after segmental cutaneous (skin surface) warming, would be affected differently by systemic warming. METHODS: Wrist-palm, palm-proximal digit, and digital sensory nerve segments were assessed antidromically by stimulating at the wrist with recording electrodes placed distally. The same subjects were cutaneously warmed in 2001 to >/=31 degrees C and were systemically warmed 28 months later in 2004 by ramped sustained exercise to 100 W for 12 min. Skin temperatures were measured by traditional thermistry and by infrared thermal images taken over the hand and wrist surfaces. RESULTS: When systemic warming was compared to segmental cutaneous warming, SNCVs were increased by 15.1% in the third digit and 20.4% in the fifth digit of the dominant hand. Respective increases in the non-dominant hand were 11.0% and 19.4%. A strong association between increased surface skin temperature and faster SNCV, which had been observed after segmental cutaneous warming, was largely eliminated for both digit and palmar anatomic segments after systemic warming. Significant differences in SNCV between vibration-exposed and non-exposed workers, which had been observed after segmental cutaneous warming, were eliminated after systemic warming. Systemic warming had only a small effect on the wrist-palm (transcarpal) segmental SNCVs. CONCLUSIONS: Reduced SNCV in the digits was observed in vibration-exposed and non-exposed workers. Substituting exercise-induced systemic warming for segmental cutaneous warming significantly increased SNCV in the digits and appeared to reduce differences in SNCV between vibration-exposed and non-exposed workers. These findings persisted despite a substantial time interval between tests, during which the subjects continued to work. There may be more general implications for diagnosing clinical conditions in industrial workers, such as the carpal tunnel syndrome and the hand-arm vibration syndrome.     

Effect of redesigned Indian mixed meals on blood glucose and insulin levels in normal versus type 2 diabetic subjects–a comparative study

This study reports the glycemic as well as insulinemic response of seven types of Indian vegetarian mixed meals (MMs). Each of the seven MMs was given at weekly intervals to both normal and type 2 diabetic subjects on the same day to reduce variations in food preparations. In this Indian study, each MM consisted of five to six food items with a low glycemic index (GI) ranging from 28.98 to 46.12%, glycemic load ranging from 15.58 to 23.8 g and energy value (calculated) from each test meal ranging from 403 to 502 kcal. All the seven meals were found to have postprandial glycemic control in normal subjects which ranged from 86 to 102.4 mg%, and a good postprandial glycemic control in type 2 diabetic subjects which ranged from 132.8 to 148.4 mg%, and hence appropriate for routine consumption by diabetic subjects. The glycemic and insulinemic pattern of all these MMs was similar in normal and diabetic subjects. Sustained intake of such low GI MMs by diabetic can result in good glycemic control.     

Effect of schisandrin B on lung mRNA expression of transforming growth factor-β1 signal transduction molecule in rat lungs exposed to silica

Objective To investigate the effects of schisandrin B (Sch-B) on expression of transforming growth factor-β1 (TGF-β1) and signal transduction molecule mRNA in rat lungs exposed to SiO2,and explore the intervention mechanism of Sch-B on pulmonary fibrosis induced by SiO2. Methods Ninety six Wistar rats were randomly divided into control (normal saline) group, SiO2 group and SiO2 plus Sch-B group.The rats were exposed to SiO2 by direct tracheal instillation to establish the silicotic animal models. SiO2 group and SiO2 plus Sch-B group were treated with 1ml SiO2 (50 mg/ml) for each rat From the first day after model establishment, SiO2 plus Sch-B group were orally given Sch-B (80 mg/kg) a day, control group and silica group were orally given olive oil. On the 3rd, 7th,14th and 28th days after treatment, 8 rats in each group were sacrificed and samples were collected. The histo-pathological examination of lung was performed by HE staining. The expression levels of TGF-β1 、TGFβR Ⅱ and Smad4 mRNA in the lung tissues were detected by RT-PCR. Results The results of histo-pathological examination showed that in SiO2 group, lung tissues were injured obviously; the alveolar inflammation with alveolus interval edema and inflammation cell infiltration appeared on the 3rd and 7th days; the alveolus interval became thicker, became thicker, fibroblast and collagen matiix increased markedly on 14th day; the alveolar structure was damaged, alveolar wall thickened obviously,collagen aggradation and pulmonary fibrosis displayed on 28th day. The alveolar inflammation and pulmonary fibrosis in SiO2 plus Sch-B group were significantly less than those in SiO2 group. The expressions levels of TGF-β1、TGFβR Ⅱ and Smad4 mRNA (TGF-β1: 1.03±0.31 、1.33±0.39、1.08±0.26、0.82±0.16,TGF-βR Ⅱ:0.65 ±0.11、0.80 ±0.16、0.83 ±0.24、0.62 ±0.15, Smad4: 0.87 ±0. 15、0.68 ±0.11、0.78 ±0.19、0.30 ±0.08) in SiO2group were significantly higher than those in the control group (TGF-β1:0.59±0.22、0.55 ±0.25、0.56±0.20、0.55 ±0.12,TGR-βR Ⅱ:0.28 ±0.13、0.31 ±0. 15、0.34 ±0.15、0.27 ±0.09,Smad4:0.23 ±0.11、0.40 ±0. 12、0.39 ±0.12、0.18±0.06)(P＜0.01 or P＜0.05), but the expression level of TGF-β1 mRNA was the highest on the 7th day. The expression levels of TGF-β1 and Smad4 mRNA (TGF-β1: 0.68 ±0.28、0.88 ±0.25、0.75 ±0.11、0.61 ±0. 14,Smad4:0.25 ±0.12、0.45 ±0.09、0.44 ±0.07、0.21 ±0.04) in SiO2 plus Sch-B group were significantly lower than those in SiO2 group (P＜0.01 or P＜0.05),but there were no significant differences of the TGFβR Ⅱ mRNA expression levels between SiO2 group and SiO2 plus Sch-B group. Conclusion Sch-B can reduce the pulmonary fibrosis induced by SiO2 through inhibition of the mRNA express of TGF-β1 and Smad4 in the lung tissue, modulating the TGF-β1/Smad4 signal transduction pathway and inhibiting the target gene activation.     

Differential effects of 1α,25-dihydroxycholecalciferol on MCP-1 and adiponectin production in human white adipocytes

Background/aim

Obesity is characterized by a low-grade inflammation in white adipose tissue (WAT), which promotes insulin resistance. Low serum levels of 1α,25-dihydroxycholecalciferol (DHCC) associate with insulin resistance and higher body mass index although it is unclear whether vitamin D supplementation improves insulin sensitivity. We investigated the effects of DHCC on adipokine gene expression and secretion in adipocytes focusing on two key factors with pro-inflammatory [monocyte chemoattractant protein-1 (MCP-1/CCL2)] and anti-inflammatory [adiponectin (ADIPOQ)] effects.

Methods

Pre-adipocytes were isolated from human subcutaneous WAT and cultured until full differentiation. Differentiated adipocytes were either pre-treated with DHCC (10^?7 M) and subsequently incubated with tumor necrosis factor-α (TNFα, 100 ng/mL) or concomitantly incubated with TNFα/DHCC. MCP1 and adiponectin mRNA expression was measured by RT–PCR and protein release by ELISA.

Results

DHCC was not toxic and did not affect adipocyte morphology or the mRNA levels of adipocyte-specific genes. TNFα induced a significant increase in CCL2 mRNA and protein secretion, while DHCC alone reduced CCL2 mRNA expression (~25%, p < 0.05). DHCC attenuated TNFα-induced CCL2 mRNA expression in both pre-incubation (~15%, p < 0.05) and concomitant (~60%, p < 0.01) treatments. TNFα reduced ADIPOQ mRNA (~80%) and secretion (~35%). DHCC alone decreased adiponectin secretion to a similar degree (~35%, p < 0.05). Concomitant treatment with DHCC/TNFα for 48 h had an additive effect, resulting in a pronounced reduction in adiponectin secretion (~70%).

Conclusions

DHCC attenuates MCP-1 and adiponectin production in human adipocytes, thereby reducing the expression of both pro- and anti-inflammatory factors. These effects may explain the difficulties so far in determining the role of DHCC in insulin sensitivity and obesity in humans.     

Misrepair of DNA double-strand breaks after exposure to heavy-ion beams causes a peak in the LET–RBE relationship with respect to cell killing in DT40 cells

To determine the radiobiological mechanisms underlying relative biological effectiveness (RBE) and the repair efficiencies of DNA double-strand breaks (DSBs) as a function of linear energy transfer (LET), we exposed cells of the chicken B-lymphocyte cell line DT40 and its DSB repair pathway-deficient derivatives to heavy-ion beams produced at the Heavy-Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences (NIRS), Chiba, Japan. The relationship between LET and cell lethality was investigated in the DNA DSB repair gene knockouts Ku70^−/−, Rad54^−/−, and Ku70^−/−Rad54^−/−, and in the wild-type cells. We found that cell-cycle stage and activity of the DNA DSB repair pathways influence LET-mediated biological effects. An expected LET–RBE relationship was observed in the cells capable of DNA repair, but no peak was found in the RBE with respect to cell survival in the Ku70^−/−Rad54^−/− cells or in Ku70^−/− cells in the G1 and early S cell-cycle phases (when no sister chromatids were present and homologous recombination could not occur). These findings suggest that the peak in RBE is caused by deficient repair of the DNA DSBs.     

Temporal variability of blood lead,mercury, and cadmium levels in elderly panel study (2008–2014)

Background

Biological measurements have been employed as useful biomarkers for exposure. Because of its property of reflecting toxicokinetic differences, however, within-subject variability leads to biased results in epidemiologic studies.

Naked DNA in cells: An inducer of major histocompatibility complex molecules to evoke autoimmune responses?

The major histocompatibility complex (MHC) is the exclusive chaperone that presents intracellular antigens, either self or foreign to T cells. Interestingly, aberrant expression of MHC molecules has been reported in various autoimmune target tissues such as thyroid follicular cells in Grave’s disease. Herein, we review the discovery of an unexpected effect of cytosolic double-stranded DNA (dsDNA), despite its origins, to induce antigen processing and presenting genes, including MHC molecules, in non-immune cells. Moreover, we highlight several recent studies that suggest cell injury endows thyroid epithelial cells with a phenotype of mature antigen presenting cells by inducing multiple antigen processing and presenting genes via releasing genomic DNA fragments into the cytosol. We discuss the possibility that such cytosolic dsDNA, in naked form without binding to histone proteins, might be involved in the development of cell damage-triggered autoimmune responses. We also discuss the possible molecular mechanism by which cytosolic dsDNA can induce MHC molecules. It is reasonable to speculate that cytosolic dsDNA-induced MHC class I is partially due to an autocrine/paracrine effect of type I interferon (IFN). While the mechanism of cytosolic dsDNA-induced MHC class II expression appears, at least partially, distinct from that mediated by IFN-γ. Further in-depth are required to clarify this picture.     

The Influence of Declining Air Lead Levels on Blood Lead–Air Lead Slope Factors in Children

Background: It is difficult to discern the proportion of blood lead (PbB) attributable to ambient air lead (PbA), given the multitude of lead (Pb) sources and pathways of exposure. The PbB–PbA relationship has previously been evaluated across populations. This relationship was a central consideration in the 2008 review of the Pb national ambient air quality standards.Objectives: The objectives of this study were to evaluate the relationship between PbB and PbA concentrations among children nationwide for recent years and to compare the relationship with those obtained from other studies in the literature.Methods: We merged participant-level data for PbB from the National Health and Nutrition Examination Survey (NHANES) III (1988–1994) and NHANES 9908 (1999–2008) with PbA data from the U.S. Environmental Protection Agency. We applied mixed-effects models, and we computed slope factor, d[PbB]/d[PbA] or the change in PbB per unit change in PbA, from the model results to assess the relationship between PbB and PbA.Results: Comparing the NHANES regression results with those from the literature shows that slope factor increased with decreasing PbA among children 0–11 years of age.Conclusion: These findings suggest that a larger relative public health benefit may be derived among children from decreases in PbA at low PbA exposures. Simultaneous declines in Pb from other sources, changes in PbA sampling uncertainties over time largely related to changes in the size distribution of Pb-bearing particulate matter, and limitations regarding sampling size and exposure error may contribute to the variability in slope factor observed across peer-reviewed studies.Citation: Richmond-Bryant J, Meng Q, Davis A, Cohen J, Lu SE, Svendsgaard D, Brown JS, Tuttle L, Hubbard H, Rice J, Kirrane E, Vinikoor-Imler LC, Kotchmar D, Hines EP, Ross M. 2014. The Influence of declining air lead levels on blood lead–air lead slope factors in children. Environ Health Perspect 122:754–760; http://dx.doi.org/10.1289/ehp.1307072     

Endotoxin level in ischemia–reperfusion injury in rats: Effect of glutamine pretreatment on endotoxin levels and gut morphology

ObjectiveWe aimed to investigate the effect of enteral glutamine (Gln) pretreatment on plasma endotoxin level and intestinal histopathologic changes during intestinal ischemia–reperfusion (I/R) injury in rats.MethodsIntestinal I/R was induced by 60-min occlusion of the superior mesenteric artery followed by 60 min of reperfusion. Animals were pretreated with Gln by orogastric route for different periods and doses. To investigate the effects of gut decontamination on intestinal I/R injury, animals were pretreated with neomycin sulfate and erythromycin phosphate by orogastric route. In another series, dl-α-tocopherol hydrogen succinate was used to investigate the effects of vitamin E on intestinal I/R injury. Plasma endotoxin level was measured by the colorimetric “limulus amebocyte lysate” test. Intestinal mucosal injury was scored on a scale described by Chiu et al. (Archive in Surgery 1970;101:478–483).ResultsIntestinal I/R increased the plasma endotoxin level and worsened the histopathologic score significantly. Gln pretreatment (1 g/kg) for 4 d reduced the I/R-induced elevation of plasma endotoxin level. However, a significant improvement in histopathologic score could only be achieved when the pretreatment was given for 7 d. Antibiotic pretreatment lowered plasma endotoxin level without affecting the I/R-induced histopathologic changes, whereas vitamin E pretreatment affected plasma endotoxin level and histopathologic changes.ConclusionThese results suggest a lack of association between plasma endotoxin level and intestinal histopathologic alterations in intestinal I/R.     

The influence of non-DNA-targeted effects on carbon ion–induced low-dose hyper-radiosensitivity in MRC-5 cells

Low-dose hyper-radiosensitivity (LDHRS) is a hot topic in normal tissue radiation protection. However, the primary causes for LDHRS still remain unclear. In this study, the impact of non-DNA-targeted effects (NTEs) on high-LET radiation–induced LDHRS was investigated. Human normal lung fibroblast MRC-5 cells were irradiated with high-LET carbon ions, and low-dose biological effects (in terms of various bio-endpoints, including colony formation, DNA damage and micronuclei formation) were detected under conditions with and without gap junctional intercellular communication (GJIC) inhibition. LDHRS was observed when the radiation dose was <0.2 Gy for all bio-endpoints under investigation, but vanished when the GJIC was suppressed. Based on the probability of cells being hit and micro-dose per cell calculation, we deduced that the LDHRS phenomenon came from the combined action of direct hits and NTEs. We concluded that GJIC definitely plays an important role in cytotoxic substance spreading in high-LET carbon ion–induced LDHRS.     

Improvement in the GC–MS method for determining urinary toluene-diamine and its application to the biological monitoring of workers exposed to toluene-diisocyanate

Objectives: To develop a simple and sensitive GC–MS method for determining toluene-diamine (TDA) in urine and to apply the method for biological monitoring of workers exposed to toluene-diisocyanate (TDI). Methods: After acid hydrolysis of 0.1 ml of urine, diluted tenfold with water, for 1.5 h, the free TDA formed was extracted with dichloromethane, and the heptafluorobutyric anhydride derivative was determined by GC–MS. We applied the method to the biological monitoring of 18 workers who were using an 80:20 mixture of 2,4-TDI and 2,6-TDI. Results: 2,6-TDA and 2,4-TDA were simply determined in 7 min by GC–MS. TDA levels in post-shift urine were well correlated with personal exposure levels of TDI. The correlation was improved by correction with creatinine or specific gravity in the 2,6-isomer, but not in the 2,4-isomer because of low exposure levels. From the correlation equation, the 2,6-TDA level (corrected with creatinine), corresponding to the TDI level of 5 ppb, was calculated to be 31.6 g/g Cre. TDAs in pre-shift urine also correlated significantly with the personal exposure levels of TDIs, although the slope of the correlations for pre-shift samples was 60%–70% of those for post-shift samples. The correlation between 2,4-TDA and 2,6-TDA levels was significant, although the levels of the 2,4-isomer were less than one-tenth of the 2,6-isomers in both air (personal exposure) and urine. Conclusion: The present method is simple and practicable and can be useful for biological monitoring of TDI workers.     

Evaluation of endogenous control gene(s) for gene expression studies in human blood exposed to 60Co γ-rays ex vivo

In gene expression studies, it is critical to normalize data using a stably expressed endogenous control gene in order to obtain accurate and reliable results. However, we currently do not have a universally applied endogenous control gene for normalization of data for gene expression studies, particularly those involving ⁶⁰Co γ-ray-exposed human blood samples. In this study, a comparative assessment of the gene expression of six widely used housekeeping endogenous control genes, namely 18S, ACTB, B2M, GAPDH, MT-ATP6 and CDKN1A, was undertaken for a range of ⁶⁰Co γ-ray doses (0.5, 1.0, 2.0 and 4.0 Gy) at 8.4 Gy min⁻¹ at 0 and 24 h post-irradiation time intervals. Using the NormFinder algorithm, real-time PCR data obtained from six individuals (three males and three females) were analyzed with respect to the threshold cycle (Ct) value and abundance, ΔCt pair-wise comparison, intra- and inter-group variability assessments, etc. GAPDH, either alone or in combination with 18S, was found to be the most suitable endogenous control gene and should be used in gene expression studies, especially those involving qPCR of γ-ray-exposed human blood samples.     

The impact of environmental and biological factors on paraoxonase 1 and γ-glutamyltranspeptydase activities in the blood of smelters

Disorders of paraoxonase and γ-glutamyltranspeptydase activities can induce development of the atherosclerotic process. The aim of the study was to examine the effect of occupational exposure to heavy metals, tobacco smoke and alcohol consumption on the activities of paraoxonase and γ-glutamyltranspeptydase as well as glutathione concentration. We have observed reduced paraoxonase activity and higher γ-glutamyltranspeptydase activity in serum of smelters when compared to control groups. In the blood of smoking smelters was demonstrated a negative correlation between paraoxonase activity and BMI value as well as between paraoxonase activity and tobacco smoke and consumption of 40 % alcohol. Also, negative correlation was found for the activity of paraoxonase and glutathione concentration as well as γ-glutamyltranspeptydase activity. Higher γ-glutamyltranspeptydase activity and lower paraoxonase activity in the serum of smelters exposed to heavy metals and tobacco smoke can cause disorders in functioning of the body.