Cranial radiotherapy in children and adults with brain tumors frequently causes abnormal hypothalamic-pituitary function. The most frequent changes are hypothyroidism and gonadal dysfunction, although subtle abnormalities in adrenal function may also be present.
Venusian impact crater size‐frequency distributions, locations, and preservation states were analyzed to reconstruct the history of resurfacing by tectonism and volcanism. An atmospheric transit model for meteoroids demonstrates that for craters larger than about 30 km, the size‐frequency distribution is close to the atmosphere‐free case. With this result, and assuming that the surface records a crater production population (a catastrophic resurfacing model, CRM), an age of cessation of rapid resurfacing of ∼ 500 Ma is obtained. Crater locations are widely dispersed across Venus and the hypothesis that they are completely spatially random (CSR) cannot be rejected. However, craters that show embayment by plains materials or modification by throughgoing faults (i.e., tectonized) are preferentially found in areas with relatively few craters overall. The primary region where these modified craters are found is the Aphrodite volcanotectonic zone, extending from Ovda Regio on the west to the region east of Atla Regio. These results, together with the appearance of plains material on most crater floors and evidence for complex volcanic stratigraphy, imply that a range of surface ages are recorded by the impact crater population; e.g., the Aphrodite zone is relatively young. An end‐member model (equilibrium resurfacing model, ERM) was developed to quantify resurfacing scenarios. In the ERM, Venus has been resurfacing at an average rate of approximately 1 km2 yr−1. However, the CRM and ERM are idealized end‐member representations of possible resurfacing histories. For both models, the resurfacing rate can be expressed as the product of resurfacing patch area a (normalized by planetary surface area) and the frequency ω of resurfacing events. Numerical simulations of resurfacing showed that there are two solution branches that satisfy the CSR constraint: a < 0.0003 (4° diameter circle ) and a > 0.1 (74° diameter circle). The former range corresponds to resurfacing diameters smaller than the average intercrater distance, whereas the latter is associated with large, infrequent events, resurfacing 10% of the planet every 50 Ma to 100% every 500 Ma. The observed fraction of embayed and tectonized craters further constrains values of a and only values near 0.0003 are admissible. The resurfacing model that best fits all of the statistical and geological constraints has resurfacing with small patches that occurs, in any given geological episode, in only a limited number of regions on the planet.
Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide ( 1 ). Dyslipidemia has been shown to be one of the most potent risk factors for coronary heart disease (CHD) ( 2, 3 ). Dyslipidemia is characterized by elevated plasma cholesterol, especially low density lipoprotein cholesterol (LDL-c) levels. Management of dyslipidemia is considered throughout the primary and secondary prevention of CHD ( 4 ). For the past 20 years, the statin (3-hydroxy-3-methylglutaryl CoA reductase inhibitors) class of cholesterol-lowering drugs has been used for the treatment of hypercholesterolemia, either alone or in combination with other classes of lipid-lowering drugs Abstract In an attempt to understand the applicability of various animal models to dyslipidemia in humans and to identify improved preclinical models for target discovery and validation for dyslipidemia, we measured comprehensive plasma lipid profi les in 24 models. These included fi ve mouse strains, six other nonprimate species, and four nonhuman primate (NHP) species, and both healthy animals and animals with metabolic disorders. Dyslipidemic humans were assessed by the same measures. Plasma lipoprotein profi les, eight major plasma lipid fractions, and FA compositions within these lipid fractions were compared both qualitatively and quantitatively across the species. Given the importance of statins in decreasing plasma low-density lipoprotein cholesterol for treatment of dyslipidemia in humans, the responses of these measures to simvastatin treatment were also assessed for each species and compared with dyslipidemic humans. NHPs, followed by dog, were the models that demonstrated closest overall match to dyslipidemic humans. For the subset of the dyslipidemic population with high plasma triglyceride levels, the data also pointed to hamster and db/db mouse as representative models for practical use in target validation. Most traditional models, including rabbit, Zucker diabetic fatty rat, and the majority of mouse models, did not demonstrate overall similarity to dyslipidemic humans in this study . -
The results provide evidence that genes involved in tissue remodeling and repair are differentially regulated in the lungs of obstructed smokers and suggest that they are potential therapeutic targets. Data deposited in GEO at http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE8500.
Paroxetine had no influence on fatigue in patients receiving chemotherapy. A possible explanation is that cancer-related fatigue does not involve a reduction in brain 5-HT levels.
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