Evaluation of the 238^{238}U Neutron Cross Section in the Unresolved Resonance Range

International audienceThis paper presents a new analysis of the $^{238}$U cross sections in the unresolved resonance range, from 20 keV to 150 keV.Statistical analysis of the resonance parameters in the resolved resonance rangewith random-matrix theory provides accurate experimental values of strength function and average level spacing for s- and p-waveresonances. Above 20 keV, the simultaneous fit of selected experimental data (average transmission and capture) is performed with a statistical model of nuclear reactionas implemented in the SAMMY code.Compared to previous evaluations, such as those described by Fröhner or by Maslov et al., this work benefits from the accurate transmission data measured by Harvey et al. at Oak Ridge Electron Linear Accelerator, which have never been studied before. This new evaluation was written into the current ENDF format for use in practical applications. This work stresses the need for an improved ENDF format to store average resonance parameters and cross sections in the unresolved resonance range

Neutron Resonance Parameters and Covariance Matrix of 239Pu

In order to obtain the resonance parameters in a single energy range and the corresponding covariance matrix, a reevaluation of 239Pu was performed with the code SAMMY. The most recent experimental data were analyzed or reanalyzed in the energy range thermal to 2.5 keV. The normalization of the fission cross section data was reconsidered by taking into account the most recent measurements of Weston et al. and Wagemans et al. A full resonance parameter covariance matrix was generated. The method used to obtain realistic uncertainties on the average cross section calculated by SAMMY or other processing codes was examined

Assessment of Fission Product Cross-Section Data for Burnup Credit Applications

Past efforts by the Department of Energy (DOE), the Electric Power Research Institute (EPRI), the Nuclear Regulatory Commission (NRC), and others have provided sufficient technical information to enable the NRC to issue regulatory guidance for implementation of pressurized-water reactor (PWR) burnup credit; however, consideration of only the reactivity change due to the major actinides is recommended in the guidance. Moreover, DOE, NRC, and EPRI have noted the need for additional scientific and technical data to justify expanding PWR burnup credit to include fission product (FP) nuclides and enable burnup credit implementation for boiling-water reactor (BWR) spent nuclear fuel (SNF). The criticality safety assessment needed for burnup credit applications will utilize computational analyses of packages containing SNF with FP nuclides. Over the years, significant efforts have been devoted to the nuclear data evaluation of major isotopes pertinent to reactor applications (i.e., uranium, plutonium, etc.); however, efforts to evaluate FP cross-section data in the resonance region have been less thorough relative to actinide data. In particular, resonance region cross-section measurements with corresponding R-matrix resonance analyses have not been performed for FP nuclides. Therefore, the objective of this work is to assess the status and performance of existing FP cross-section and cross-section uncertainty data in the resonance region for use in burnup credit analyses. Recommendations for new cross-section measurements and/or evaluations are made based on the data assessment. The assessment focuses on seven primary FP isotopes (103Rh, 133Cs, 143Nd, 149Sm, 151Sm, 152Sm, and 155Gd) that impact reactivity analyses of transportation packages and two FP isotopes (153Eu and 155Eu) that impact prediction of 155Gd concentrations. Much of the assessment work was completed in 2005, and the assessment focused on the latest FP cross-section evaluations available in the international nuclear data community as of March 2005. The accuracy of the cross-section data was investigated by comparing existing cross-section evaluations against available measured cross-section data. When possible, benchmark calculations were also used to assess the performance of the latest FP cross-section data. Since March 2005, the U.S. and European data projects have released newer versions of their respective data files. Although there have been updates to the international data files and to some degree FP data, much of the updates have included nuclear cross-section modeling improvements at energies above the resonance region. The one exception is improved ENDF/B-VII cross-section uncertainty data or covariance data for gadolinium isotopes. In particular, ENDF/B-VII includes improved 155Gd resonance parameter covariance data, but they are based on previously measured resonance data. Although the new covariance data are available for 155Gd, the conclusions of the FP cross-section data assessment of this report still hold in lieu of the newer international cross-section data files. Based on the FP data assessment, there is judged to be a need for new total and capture cross-section measurements and corresponding cross-section evaluations, in a prioritized manner, for the nine FPs to provide the improved information and technical rigor needed for criticality safety analyses

Antinociceptive Activity of Trichilia catigua Hydroalcoholic Extract: New Evidence on Its Dopaminergic Effects

Trichilia catigua is a native plant of Brazil; its barks are used by some local pharmaceutical companies to prepare tonic drinks, such as Catuama. The present study was addressed to evaluate the effects of T. catigua hydroalcoholic extract in mouse nociception behavioral models, and to evaluate the possible mechanisms involved in its actions. Male Swiss mice were submitted to hot-plate, writhing and von Frey tests, after oral treatment with T. catigua extract (200 mg kg−1, p.o.). The extract displayed antinociceptive effect in all three models. For characterization of the mechanisms involved in the antinociceptive action of the extract, the following pharmacological treatments were done: naloxone (2.5 mg kg−1, s.c.), SR141716A (10 mg kg−1, i.p.), SCH23390 (15 μg kg−1, i.p.), sulpiride (50 mg kg−1, i.p.), prazosin (1 mg kg−1, i.p.), bicuculline (1 mg kg−1, i.p.) or dl-p-chlorophenylalanine methyl ester (PCPA, 100 mg kg−1, i.p.). In these experiments, the action of T. catigua extract was evaluated in the hot-plate test. The treatment with SCH23390 completely prevented the antinociceptive effect, while naloxone partially prevented it. The possible involvement of the dopaminergic system in the actions of T. catigua extract was substantiated by data showing the potentiation of apomorphine-induced hypothermia and by the prevention of haloperidol-induced catalepsy. In conclusion, the antinociceptive effects of T. catigua extract seem to be mainly associated with the activation of dopaminergic system and, to a lesser extent, through interaction with opioid pathway

Histochemical Characterization, Distribution and Morphometric Analysis of NADPH Diaphorase Neurons in the Spinal Cord of the Agouti

We evaluated the neuropil distribution of the enzymes NADPH diaphorase (NADPH-d) and cytochrome oxidase (CO) in the spinal cord of the agouti, a medium-sized diurnal rodent, together with the distribution pattern and morphometrical characteristics of NADPH-d reactive neurons across different spinal segments. Neuropil labeling pattern was remarkably similar for both enzymes in coronal sections: reactivity was higher in regions involved with pain processing. We found two distinct types of NADPH-d reactive neurons in the agouti's spinal cord: type I neurons had large, heavily stained cell bodies while type II neurons displayed relatively small and poorly stained somata. We concentrated our analysis on type I neurons. These were found mainly in the dorsal horn and around the central canal of every spinal segment, with a few scattered neurons located in the ventral horn of both cervical and lumbar regions. Overall, type I neurons were more numerous in the cervical region. Type I neurons were also found in the white matter, particularly in the ventral funiculum. Morphometrical analysis revealed that type I neurons located in the cervical region have dendritic trees that are more complex than those located in both lumbar and thoracic regions. In addition, NADPH-d cells located in the ventral horn had a larger cell body, especially in lumbar segments. The resulting pattern of cell body and neuropil distribution is in accordance with proposed schemes of segregation of function in the mammalian spinal cord

Organic consequences of ileal transposition in rats with diet-induced obesity

INTRODUCTION: The clinical management of metabolic syndrome - especially diabetes mellitus type 2 - is notoriously complex due to the progressive nature of this disease. At present, there is a need for a surgical procedure that is effective for the treatment of diabetes mellitus type 2, even in non-obese individuals. The isolated ileal transposition theory could lead to an effective alternative therapy. This intervention has not yet been performed in humans, and there are no reports of its use in an experimental model of diet-induced metabolic syndrome.
 OBJECTIVES: The objective of this study is to evaluate the physiological effects of ileal transposition in rats with diet-induced metabolic syndrome. The effects of this procedure on glucose and lipid metabolism will be assessed. 
METHODS: Forty 12-week-old male rats (albino Rattus norvegicus, Wistar, 2BAW, heterogeneous) will be divided into four groups of 10 animals each: the ileal transposition group (TG) comprising animals on a hypercaloric-hyperlipidic diet; the sham group (SG) containing animals that receive the same diet and undergo the sham surgery; control group 1 (CG1), which will receive a hypercaloric-hyperlipidic diet and will not undergo surgery; and control group 2 (CG2), which will consume standard feed and will not undergo surgery. The surgeries will be performed in 20-week-old animals. Blood samples for laboratory testing will be collected from 12-week-old animals on the day of surgery and after eight postoperative weeks, following determination of the weights of the animals and the administration of anesthesia. The levels of serum glucose, insulin, triglycerides, total cholesterol and fractions, glucagon-like peptide-1, C-peptide and glycated hemoglobin will be assessed in all of the animals. The insulin tolerance test will be performed using PRISMA software, and insulin resistance will be calculated by the HOMA-IR indirect test. On specific days, two 20-week-old rats will be separated and randomly distributed in TG and SG. These animals will be followed until the eighth postoperative week. Subsequently, they will be euthanized, and the retroperitoneal and periepididymal fat deposits will be collected and weighed using a precision scale. In addition, the pancreas, liver and intestinal segments will be sent for pathological and immunohistochemical studies.
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Isolated ileal interposition in enteroendocrine L cells differentiation

INTRODUCTION: 
Due to the progressive nature of type 2 diabetes, its complexity and drug treatment perpetuity, there is currently a search for surgical procedures that can promote euglycemia also in non-obese patients. Diabetic patients glycemic control can be achieved by increasing the blood concentration of GLP-1, a hormone produced by L cells that are more densely concentrated in the terminal ileum. Early and extended improvement of diabetes in patients submitted to bariatric surgeries awakened the necessity of investigating the isolated ileal interposition as a surgical alternative for the treatment of diabetes. The interposition of this ileal segment to a more anterior region (proximal jejunum) can promote a greater stimulation of the L cells by poorly digested food, increasing the production of GLP-1 and reflecting on glycemic control. However, in order to consolidate the ileal interposition as a surgical treatment of diabetes it is necessary that the interposed ileum keep the same differentiation rate into L cells for a long period to justify the intervention.

AIMS: 
To investigate the isolated ileal interposition influence on the differentiation of intestinal precursor cells into enteroendocrine L cells over time.

METHODS: 
Twelve 12-week-old male Wistar rats (Rattus norvegicus albinus) of the WAB strain (heterogeneous) will be used. All animals will receive a high-calorie, high-fat diet for 16 weeks or more until they develop glucose dysmetabolism confirmed by glycemic test. They will be divided into two groups of 10 animals each: the isolated ileal interposition group (GI) and the control group (GC), comprising animals that will not be submitted to any surgical intervention. Blood samples will be collected under anesthesia at the weeks 12, 26, 36 and 44 for the determination of serum levels of glucose, insulin, GLP-1, glucagon, C-peptide and glycosilated hemoglobin. The insulin tolerance test will be performed and insulin resistance will be calculated. For the comparative analysis of the ileal precursor cells differentiation into enteroendocrine cells among the two groups, the following intestinal fragments will be collected after euthanasia: interposed ileum and remaining ileum from GI, jejunum and ileum from GC. These fragments will be analyzed by imunofluorescence and also by Real Time PCR using PCR Arrays for target genes including the main ones related to stem cell, stem cell signaling, diabetes, Wnt and Notch signaling pathways and other genes and pathways involved in the differentiation of intestinal precursor cells into enteroendocrine cells, especially GLP-1-producing L cells that play important role in euglycemia

Antinociceptive Activity of Trichilia catigua Hydroalcoholic Extract: New Evidence on Its Dopaminergic Effects

Trichilia catigua is a native plant of Brazil; its barks are used by some local pharmaceutical companies to prepare tonic drinks, such as Catuama. The present study was addressed to evaluate the effects of T. catigua hydroalcoholic extract in mouse nociception behavioral models, and to evaluate the possible mechanisms involved in its actions. Male Swiss mice were submitted to hot-plate, writhing and von Frey tests, after oral treatment with T. catigua extract (200 mg kg −1 , p.o.). The extract displayed antinociceptive effect in all three models. For characterization of the mechanisms involved in the antinociceptive action of the extract, the following pharmacological treatments were done: naloxone (2.5 mg kg −1 , s.c.), SR141716A (10 mg kg −1 , i.p.), SCH23390 (15 μg kg −1 , i.p.), sulpiride (50 mg kg −1 , i.p.), prazosin (1 mg kg −1 , i.p.), bicuculline (1 mg kg −1 , i.p.) or dl-p-chlorophenylalanine methyl ester (PCPA, 100 mg kg −1 , i.p.). In these experiments, the action of T. catigua extract was evaluated in the hot-plate test. The treatment with SCH23390 completely prevented the antinociceptive effect, while naloxone partially prevented it. The possible involvement of the dopaminergic system in the actions of T. catigua extract was substantiated by data showing the potentiation of apomorphineinduced hypothermia and by the prevention of haloperidol-induced catalepsy. In conclusion, the antinociceptive effects of T. catigua extract seem to be mainly associated with the activation of dopaminergic system and, to a lesser extent, through interaction with opioid pathway

HERV-K and HERV-W transcriptional activity in myalgic encephalomyelitis/chronic fatigue syndrome.

BACKGROUND: Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/MS) is an incapacitating chronic disease that dramatically compromise the life quality. The CFS/ME pathogenesis is multifactorial, and it is believed that immunological, metabolic and environmental factors play a role. It is well documented an increased activity of Human endogenous retroviruses (HERVs) from different families in autoimmune and neurological diseases, making these elements good candidates for biomarkers or even triggers for such diseases. METHODS: Here the expression of Endogenous retroviruses K and W (HERV-K and HERV-W) was determined in blood from moderately and severely affected ME/CFS patients through real time PCR. RESULTS: HERV-K was overexpressed only in moderately affected individuals but HERV-W showed no difference. CONCLUSIONS: This is the first report about HERV-K differential expression in moderate ME/CFS. Although the relationship between HERVs and ME/CFS has yet to be proven, the observation of this phenomenon deserves further attention