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Exposure Parameters (exposure + parameter)
Selected AbstractsCorrelation of IMPDH1 Gene Polymorphisms with Subclinical Acute Rejection and Mycophenolic Acid Exposure Parameters on Day 28 after Renal TransplantationBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 2 2010Hideaki Kagaya The correlations with subclinical acute rejection, IMPDH1 polymorphisms and MPA exposure on day 28 post-transplantation were investigated in 82 Japanese recipients. Renal transplant recipients were given combination immunosuppressive therapy consisting of tacrolimus and 1.0, 1.5 or 2.0 g/day of MMF in equally divided doses every 12 hr at designated times. There were no significant differences in the incidence of subclinical acute rejection between IMPDH1 rs2278293 or rs2278294 polymorphisms (p = 0.243 and 0.735, respectively). However, in the high MPA night-time exposure range (AUC >60 ,g·h/ml and C0 , 1.9 ,g/ml), there was a significant difference in the incidence of subclinical acute rejection between IMPDH1 rs2278293 A/A, A/G and G/G genotypes (each p = 0.019), but not the IMPDH1 rs2278294 genotype. In the higher daytime MPA exposure range, patients with the IMPDH1 rs2278293 G/G genotype also tended to develop subclinical acute rejection. In patients with the IMPDH rs2278293 A/A genotype, the risk of subclinical acute rejection episode tends to be low and the administration of MMF was effective. The risk of subclinical acute rejection for recipients who cannot adapt in therapeutic drug monitoring (TDM) of MPA seems to be influenced by IMPDH1 rs2278293 polymorphism. The prospective analysis of IMPDH1 rs2278293 polymorphism as well as monitoring of MPA plasma concentration after transplantation might help to improve MMF therapy. [source] Exposure to ELF magnetic field tuned to Zn inhibits growth of cancer cellsBIOELECTROMAGNETICS, Issue 8 2005Ruslan Sarimov Abstract The effects of ELF alternating magnetic fields tuned to Zn2+ on the growth of cancer cells with different status of p53 were investigated using a cell proliferation assay. Human cancer cells HeLa (cervix cancer, p53+/+), Saos-2 and Saos-2-His-273 (osteosarcoma, p53,/, and p53 His-273 mutant, respectively), H1299tTA and H1299tTA-His175 (lung carcinoma, p53,/, and p53 His-175 mutant), and normal human fibroblasts VH-10 (p53+/+) were used. Exposure parameters were calculated for the first harmonic of Zn2+ based either on the magnetic parametric resonance (MPR) model of Lednev or the ion parametric resonance (IPR) model of Blanchard and Blackman. ELF exposure was for 72 and 96 h. The vertical alternating field was 20 Hz at amplitudes of either 38.7 or 77.4 ,T (peaks, IPR or MPR, respectively). The vertical static magnetic field was 43 ,T, and the horizontal static magnetic field was zeroed. Treatments of cells with PRIMA-1 and ,-rays were used as positive controls. Growth inhibition was observed in cells after exposure to ELF at 38.7 ,T. Inhibition of HeLa, VH-10, and Saos-2-His-273 cells was statistically significant, P,=,0.0003, 0.02, and 0.006, respectively. No consistent ELF effects following exposure 77.4 ,T were seen. PRIMA-1 inhibited the growth of all cell lines with the strongest effect in mutant p53-carrying cell line H1299tTA-His175. The effects of ,-rays were relatively weak, suggesting that the cell proliferation assay under conditions employed in this study is not very sensitive to apoptosis. In conclusion, ELF under conditions of exposure tuned to Zn2+ according to the IPR model inhibited the growth of cancer and normal cells. No clear relationship of the observed growth inhibition to p53 status was found. Further experiments, using complementary techniques, are required to test whether p53 reactivation by ELF is feasible. Bioelectromagnetics 26: 2005. © 2005 Wiley-Liss, Inc. [source] Subclinical vascular alterations in young adults with type 1 diabetes detected by arterial tonometryDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 8 2009I. Barchetta Abstract Background Diabetes mellitus is characterized by a very high prevalence of atherosclerotic disease. Aims of this study were to determine arterial compliance parameters in type 1 diabetes (T1D) patients as an expression of early pre-clinical endothelial dysfunction and to evaluate the impact of glucose exposure parameters such as the duration of diabetes and glycosylated haemoglobin (HbA1c) on the risk of developing alterations in vascular compliance. Methods 23 patients with uncomplicated type 1 diabetes (mean age: 32.78 ± 9.06 years, mean disease duration: 10.78 ± 7.51 years, mean HbA1c levels: 7.7 ± 1.9) and 26 age- and sex-matched healthy subjects (mean age: 32.3 ± 8.51 years) were recruited. In these subjects, we evaluated arterial compliance by calibrated tonometry (HDI/PulsewaveÔ CR-2000). Parameters included the following: large artery elasticity (C1), small artery elasticity (C2), systemic vascular resistance (SVR) and total vascular impedance (TVI). Results Patients with longer duration of T1D (>10 years) showed significant alterations in C2 (4.97 ± 2.7 mL/mmHg × 100) and in SVR (1464.67 ± 169.16 dina × s × cm,5) when compared with both healthy individuals (C2: 8.28 ± 2.67 mL/mmHg × 100, p = 0.001; SVR: 1180.58 ± 151.55 dina × s × cm,5, p = 0.01) and patients with recent-onset disease (,10 years) (C2: 10.02 ± 3.6 mL/mmHg × 100, p < 0.001; SVR: 1124.18 ± 178.5 dina × s × cm,5, p < 0.000). Both disease duration and HbA1c independently predicted impaired arterial compliance. Conclusions Young adult T1D patients with no signs of disease complication have detectable vessel wall abnormalities, particularly of small arteries, suggestive of hyperglycaemia-related early endothelial dysfunction. Copyright © 2009 John Wiley & Sons, Ltd. [source] Imaging of root canal fillings: a comparison of subjective image quality between limited cone-beam CT, storage phosphor and film radiographyINTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2007E. So Abstract Aim, To compare the subjective quality of limited cone-beam computed tomography (LCBCT), storage phosphor plate (SPP) and F-speed film images for the evaluation of length and homogeneity of root fillings. Methodology, Root canals of 17 extracted permanent mandibular incisor teeth were filled. With the teeth placed in their jaws, images were obtained with Accu-I-Tomo LCBCT, Digora® Optime image plate system and F-speed film using exposure parameters yielding ,clinically' acceptable density and contrast. Three radiologists and three endodontists independently rated the quality of all images in respect to homogeneity and the length of root fillings using a 3-graded scale. Evaluations were undertaken in two sessions. In the first, the coronal LCBCT images were not included. In the second, both coronal and sagittal LCBCT images were rated along with F-speed film and SPP images. Results were compared using the Friedman test (P < 0.05). Pair-wise comparisons of systems were completed using the Wilxocon signed-ranks test (P < 0.05). Kappa was used to measure interobserver agreement. Results, Digora images were rated superior, consecutively followed by F-speed films and LCBCT images, for the evaluation of both homogeneity and length of root fillings in both the evaluation sessions (P < 0.05). Kappa ranged from slight to moderate for the length evaluation of root fillings and from poor to fair for the evaluation of homogeneity of root fillings. Conclusion, Image quality of storage phosphor images was subjectively as good as conventional film images and superior to LCBCT images for the evaluation of both homogeneity and length of root fillings in single-rooted teeth. [source] Total imprecision of exposure biomarkers: implications for calculating exposure limitsAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 10 2007Philippe Grandjean MD Abstract Background Assessment of the imprecision of exposure biomarkers usually focuses on laboratory performance only. Unrecognized imprecision leads to underestimation of the true toxicity of the exposure. We have assessed the total imprecision of exposure biomarkers and the implications for calculation of exposure limits. Methods In a birth cohort study, mercury concentrations in cord blood, cord tissue, and maternal hair were used as biomarkers of prenatal methylmercury exposure. We determined their mutual correlations and their associations with the child's neurobehavioral outcome variables at age 7 years. With at least three exposure parameters available, factor analysis and structural equation modeling could be applied to determine the total imprecision of each biomarker. The estimated imprecision was then applied to adjust benchmark dose calculations and the derived exposure limits. Results The exposure biomarkers correlated well with one another, but the cord blood mercury concentration showed the best associations with neurobehavioral deficits. Factor analysis and structural equation models showed a total imprecision of the cord-blood parameter of 25,30%, and almost twice as much for maternal hair. These imprecisions led to inflated benchmark dose levels. Adjusted calculations resulted in an exposure limit 50% below the level recommended by the U.S. National Research Council. Conclusions The biomarker imprecisions of 25,50% much exceeded normal laboratory variability. Such imprecision causes underestimation of dose-related toxicity and therefore must be considered in the data analysis and when deriving exposure limits. Future studies should ideally include at least three exposure parameters to allow independent assessment of total imprecision. Am. J. Ind. Med. 50:712,719, 2007. © 2007 Wiley-Liss, Inc. [source] Electromagnetic field exposure and health among RF plastic sealer operatorsBIOELECTROMAGNETICS, Issue 1 2004Jonna Wilén Abstract Operators of RF plastic sealers (RF operators) are an occupational category highly exposed to radiofrequency electromagnetic fields. The aim of the present study was to make an appropriate exposure assessment of RF welding and examine the health status of the operators. In total, 35 RF operators and 37 controls were included. The leakage fields (electric and magnetic field strength) were measured, as well as induced and contact current. Information about welding time and productivity was used to calculate time integrated exposure. A neurophysiological examination and 24 h ECG were also carried out. The participants also had to answer a questionnaire about subjective symptoms. The measurements showed that RF operators were exposed to rather intense electric and magnetic fields. The mean values of the calculated 6 min, spatially averaged E and H field strengths, in line with ICNIRP reference levels, are 107 V/m and 0.24 A/m, respectively. The maximum measured field strengths were 2 kV/m and 1.5 A/m, respectively. The induced current in ankles and wrists varied, depending on the work situation, with a mean value of 101 mA and a maximum measured value of 1 A. In total, 11 out of 46 measured RF plastic sealers exceeded the ICNIRP reference levels. RF operators, especially the ready made clothing workers had a slightly disturbed two-point discrimination ability compared to a control group. A nonsignificant difference between RF operators and controls was found in the prevalence of subjective symptoms, but the time integrated exposure parameters seem to be of importance to the prevalence of some subjective symptoms: fatigue, headaches, and warmth sensations in the hands. Further, RF operators had a significantly lower heart rate (24 h registration) and more episodes of bradycardia compared to controls. Bioelectromagnetics 25:5,15, 2004. © 2003 Wiley-Liss, Inc. [source] | ||||||||||