To predict uranium in human hair due to chronic exposure through drinking water, a compartment representing human hair was added into the uranium biokinetic model developed by the International Commission on Radiological Protection (ICRP). The hair compartmental model was used to predict uranium excretion in human hair as a bioassay indicator due to elevated uranium intakes. Two excretion pathways, one starting from the compartment of plasma and the other from the compartment of intermediate turnover soft tissue, are assumed to transfer uranium to the compartment of hair. The transfer rate was determined from reported uranium contents in urine and in hair, taking into account the hair growth rate of 0.1 g d(-1). The fractional absorption in the gastrointestinal tract of 0.6% was found to fit best to describe the measured uranium levels among the users of drilled wells in Finland. The ingestion dose coefficient for (238)U, which includes its progeny of (234)Th, (234m)Pa, and (234)Pa, was calculated equal to 1.3 x 10(-8) Sv Bq(-1) according to the hair compartmental model. This estimate is smaller than the value of 4.5 x 10(-8) Sv Bq(-1) published by ICRP for the members of the public. In this new model, excretion of uranium through urine is better represented when excretion to the hair compartment is accounted for and hair analysis can provide a means for assessing the internal body burden of uranium. The model is applicable for chronic exposure as well as for an acute exposure incident. In the latter case, the hair sample can be collected and analyzed even several days after the incident, whereas urinalysis requires sample collection shortly after the exposure. The model developed in this study applies to ingestion intakes of uranium.
Purpose: To investigate the contribution to the photopic negative response (PhNR) of the electroretinogram (ERG) by retinal ganglion cells (RGCs). The PhNR was assessed longitudinally following optic nerve transection (ONTx). Methods: Photopic ERGs were recorded from each eye of an anesthetized (ketamine/xylazine, 60 mg/kg and 5 mg/kg) Brown Norway rat using custom made electrodes (PT-IR Tef., A-M System Inc). ERGs were elicited using green Ganzfeld flashes (11.38 scd/m(2), 22.76 cds/m(2)) and a rod suppressing green-background (40 cd/m(2)). PhNRs were compared before and after optic nerves were transected. Cresyl violet stained retinal flatmounts were used to estimate cell loss in the ganglion cell layer 3 and 15 weeks after optic nerve transection. The pharmacological effect of 1.3 muM intravitreal TTX on the PhNR was also evaluated. Results: There was a significant loss (p
Patients with focal intractable epilepsy and normal MR imaging findings frequently undergo further diagnostic tests to localize the epileptogenic zone. The aim of this study was to determine the cost-effective diagnostic strategy that will identify the epileptogenic zone in patients with suspected focal intractable epilepsy and normal MR imaging findings by using decision analysis.
A Markov decision model was constructed by using sensitivities and specificities of test strategies, seizure outcomes following surgical and medical treatment, cost, utilities, probabilities, and standardized mortality ratios. We compared 6 diagnostic test strategies: PET, ictal SPECT, and MEG individually; and combinations of PET+SPECT, PET+MEG, and SPECT+MEG. The outcomes measured were health care costs, QALY, and ICER. One-way and probabilistic sensitivity analyses were conducted to adjust for uncertainties in model parameters.
The preferred strategies were PET+MEG and SPECT. The health care cost of the baseline strategy (PET+MEG) was $95,612 with 16.30 QALY gained. SPECT cost $97,479 with 16.45 QALY gained and an ICER of $12,934/QALY gained compared with those in PET+MEG. One-way sensitivity analyses showed that the decisions of the model were sensitive to variations in sensitivity and specificity of the test strategies. Probabilistic sensitivity analysis showed that when the willingness to pay was $10,000.
PET+MEG and SPECT were the preferred strategies in the base case. The choice of test was dependent on the sensitivity and specificity of test strategies and willingness to pay. Further study with a larger sample size is needed to obtain better estimates of sensitivity and specificity of diagnostic tests.
Dry matter intake (DMI) is a key component of feed efficiency in dairy cattle. In this study, we estimated genetic parameters of DMI over the first 24 lactation weeks in 3 dairy cattle breeds: Holstein, Nordic Red, and Jersey. In total, 1,656 primiparous cows (717 Holstein, 663 Nordic Red, and 276 Jersey) from Denmark, Finland, and Sweden were studied. For each breed, variance components, heritability, and repeatability for weekly DMI were estimated in 6 consecutive periods of the first 24 lactation weeks based on a repeatability animal model. Genetic correlations for DMI between different lactation periods were estimated using bivariate models. Based on our results, Holstein and Nordic Red cows had similar DMI at the beginning of lactation, but later in lactation Holstein cows had a slightly higher DMI than Nordic Red cows. In comparison, Jersey cows had a significantly lower DMI than the other 2 breeds within the first 24 lactation weeks. Heritability estimates for DMI ranged from 0.20 to 0.40 in Holsteins, 0.25 to 0.41 in Nordic Red, and 0.17 to 0.42 in Jerseys within the first 24 lactation weeks. Genetic and phenotypic variances for DMI varied along lactation within each breed and tended to be higher in the middle of lactation than at the beginning of the lactation. High genetic correlations were noted for DMI in lactation wk 5 to 24 in all 3 breeds, whereas DMI at early lactation (lactation wk 1 to 4) tended to be genetically different from DMI in the middle of lactation. The 3 breeds in this study might differ in their genetic variances for DMI, but the differences were not statistically significant in most of the studied periods. Breed differences for the genetic variance tended to be more obvious than for heritability. The potential breed differences in genetic variation for DMI should be considered in a future study using feed intake information from multiple breeds.
Imbalance was revealed in the proportions of T-lymphocyte subpopulations in those persons engaged in activity in mining employment who had been exposed to a complex of the radiation accident factors. Maximum reduction in the lymphocyte suppressor activity was recordable in those patients in whom the doses of radioactive irradiation received exceeded 25 s Gy. Depression was found of humoral immunity manifested by a drop in the absolute as well as relative numbers of B-lymphocytes and fall in the blood serum levels of Ig G, A. The results of study of clinical-biochemical and immunologic parameters of blood permit individualized therapies be developed, prophylactic measures to be devised to deal with the relevant pathologic processes and conditions in the cohorts examined.
To assess the reproducibility of myelin water fraction (MWF) and geometric mean T2 (GMT2 ), which are in vivo markers of pathological changes underlying disability and progression in diseases such as multiple sclerosis.
Five healthy volunteers were scanned twice within 24 hours at six different sites using the same manufacturer's 3T magnetic resonance (MR) system. T2 distributions were produced by fitting multiecho 3D T2 data using non-negative least squares, with stimulated echo correction. MWF, the fraction of signal with T2 between 15 and 40 msec to the entire signal, and GMT2 , the mean T2 on a logarithmic scale from T2 between 40 and 200 msec, were examined in white matter.
Intrasite coefficients of variation (COVs) were low (mean 3.99% for MWF and 0.51% for GMT2 ), as were intersite COVs (mean 4.68% for MWF, 0.31% for GMT2 ). Scan-rescan intraclass correlation coefficients (ICCs) (0.76 for MWF and 0.93 for GMT2 ) and Bland-Altman plots indicated good agreement between single site scans. Intersite ICCs were relatively high (0.69 for MWF and 0.92 for GMT2 ), revealing good intersite reliability.
MWF and GMT2 measures are reproducible between scans and across sites with an equivalent MR scanner and sequence protocol. Multicenter clinical trials using quantitative T2 relaxation are feasible.