Vasoreactivity to hypercapnia has been used for assessing cerebrovascular tone and control altered by ischemic stroke. Despite the high prognostic potential, traits of hypercapnia-induced hemodynamic changes have not been fully characterized in relation with baseline vascular states and brain tissue damage. To monitor cerebrovascular responses, T2- and T2*-weighted magnetic resonance imaging (MRI) images were acquired alternatively using spin- and gradient-echo echo plannar imaging (GESE EPI) sequence with 5% CO2 gas inhalation in normal (n=5) and acute stroke rats (n=10). Dynamic relative changes in cerebrovascular volume (CBV), microvascular volume (MVV), and vascular size index (VSI) were assessed from regions of interest (ROIs) delineated by the percent decrease of apparent diffusion coefficient (ADC). The baseline CBV was not affected by middle cerebral artery occlusion (MCAO) whereas the baseline MVV in ischemic areas was significantly lower than that in the rest of the brain and correlated with ADC. Vasoreactivity to hypercapnic challenge was considerably attenuated in the entire ipsilesional hemisphere including normal ADC regions, in which unsolicited, spreading depression-associated increases of CBV and MVV were observed. The lesion-dependent inhomogeneity in baseline MVV indicates the effective perfusion reserve for accurately delineating the true ischemic damage while the cascade of neuronal depolarization is probably responsible for the hemispherically lateralized changes in overall neurovascular physiology. 相似文献
Improving the dietary quality of women and children is essential to reduce all forms of malnutrition. In this study, we assessed seasonal child and maternal dietary diversity and consumption of animal‐source foods (ASF), using 1,236 observations from combined data collected among 167 mother–child dyads in rural Timor‐Leste. We used generalized linear and logistic mixed‐effects models to examine the dietary differentials of mothers and children in two agricultural livelihood zones and across the seasons, as well as to identify household and agroecological characteristics associated with children's dietary quality in relation to their mothers'. We found dietary quality to be marginally better in coastal than in mid‐altitude zones. However, women's diets were strikingly poor, and their intake of ASF was lower than among children. Mothers exhibited preferential allocation patterns of specific ASF, dairy products and eggs, to children. The intake of ASF was predicted by seasonality. Flesh foods and red meat were much more likely to be consumed during the dry season, when cultural ceremonies are often performed. We found a positive and strongly significant association between children's dietary indicators—dietary diversity score, minimum dietary diversity and ASF consumption, and those of their mothers'. Maternal dietary quality and educational attainment, more so than agroecological characteristics, were explanatory factors of children's diet. Our study highlights that addressing the dietary quality of children in Timor‐Leste would benefit from improving women's diets through better access to nutritious foods and to secondary education. 相似文献
Introduction: There are at the minimum two major, quite different approaches to advance drug discovery. The first being the target-based drug discovery (TBDD) approach that is commonly referred to as the molecular approach. The second approach is the phenotype-based drug discovery (PBDD), also known as physiology-based drug discovery or empirical approach.
Area covered: The authors discuss, herein, the need for developing radiation countermeasure agents for various sub-syndromes of acute radiation syndromes (ARS) following TBDD and PBDD approaches. With time and continuous advances in radiation countermeasure drug development research, the expectation is to have multiple radiation countermeasure agents for each sub-syndrome made available to radiation exposed victims.
Expert opinion: The majority of the countermeasures currently being developed for ARS employ the PBDD approach, while the TBDD approach is clearly under-utilized. In the future, an improved drug development strategy might be a ‘hybrid’ strategy that is more reliant on TBDD for the initial drug discovery via large-scale screening of potential candidate agents, while utilizing PBDD for secondary screening of those candidates, followed by tertiary analytics phase in order to pinpoint efficacious candidates that target the specific sub-syndromes of ARS. 相似文献
1. The utility of 1-aminobenzotriazole (ABT), incorporated in food, has been investigated as an approach for longer term inhibition of cytochrome P450 (P450) enzymes in mice.
2. In rats, ABT inhibits gastric emptying, to investigate this potential limitation in mice we examined the effect of ABT administration on the oral absorption of NVS-CRF38. Two hour prior oral treatment with 100?mg/kg ABT inhibited the oral absorption of NVS-CRF38, Tmax was 4?hours for ABT-treated mice compared to 0.5?hours in the control group.
3. A marked inhibition of hepatic P450 activity was observed in mice fed with ABT containing food pellets for 1?month. P450 activity, as measured by the oral clearance of antipyrine, was inhibited on day 3 (88% of control), week 2 (83% of control) and week 4 (80% of control).
4. Tmax values for antipyrine were comparable between ABT-treated mice and the control group, alleviating concerns about impaired gastric function.
5. Inclusion of ABT in food provides a minimally invasive and convenient approach to achieve longer term inhibition of P450 activity in mice. This model has the potential to enable pharmacological proof-of-concept studies for research compounds which are extensively metabolised by P450 enzymes. 相似文献
Several research teams have focused on finding the “ideal” animal model that reflects the pathophysiological changes and closely simulates the metabolic characteristics of patients with type 2 diabetes. However, the multitude of studies on this topic has resulted in large variations, making the models difficult to compare, as the measured parameters vary significantly. Additionally, selecting the appropriate animal model for a new study has become more difficult due to the increasing number of background variables. This article gives a detailed overview of the literature, covering the entire range of animal models and model characteristics, and most importantly, provides guidance for selecting the most suitable model for specific research goals in the future. 相似文献
Despite decades of vaccination, surveillance, and biosecurity measures, H5N2 low pathogenicity avian influenza (LPAI) virus infections continue in Mexico and neighboring countries. One explanation for tenacity of H5N2 LPAI in Mexico is the antigenic divergence of circulating field viruses compared to licensed vaccines due to antigenic drift. Our phylogenetic analysis indicates that the H5N2 LPAI viruses circulating in Mexico and neighboring countries since 1994 have undergone antigenic drift away from vaccine seed strains. Here we evaluated the efficacy of a new recombinant fowlpox virus vector containing an updated H5 insert (rFPV-H5/2016), more relevant to the current strains circulating in Mexico. We tested the vaccine efficacy against a closely related subcluster 4 Mexican H5N2 LPAI (2010 H5/LP) virus and the historic H5N2 HPAI (1995 H5/HP) virus in White Leghorn chickens. The rFPV-H5/2016 vaccine provided hemagglutinin inhibition (HI) titers pre-challenge against viral antigens from both challenge viruses in almost 100% of the immunized birds, with no differences in number of birds seroconverting or HI titers among all tested doses (1.5, 2.0, and 3.1 log10 mean tissue culture infectious doses/bird). The vaccine conferred 100% clinical protection and a significant decrease in oral and cloacal virus shedding from 1995 H5/HP virus challenged birds when compared to the sham controls at all tested doses. Virus shedding titers from vaccinated 2010 H5/LP virus challenged birds significantly decreased compared to sham birds especially at earlier time points. Our results confirm the efficacy of the new rFPV-H5/2016 against antigenic drift of LPAI virus in Mexico and suggest that this vaccine would be a good candidate, likely as a primer in a prime-boost vaccination program. 相似文献