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排序方式: 共有465条查询结果,搜索用时 599 毫秒
71.
Sundareswaran KS Pekkan K Dasi LP Whitehead K Sharma S Kanter KR Fogel MA Yoganathan AP 《American journal of physiology. Heart and circulatory physiology》2008,295(6):H2427-H2435
Little is known about the impact of the total cavopulmonary connection (TCPC) on resting and exercise hemodynamics in a single ventricle (SV) circulation. The aim of this study was to elucidate this mechanism using a lumped parameter model of the SV circulation. Pulmonary vascular resistance (1.96+/-0.80 WU) and systemic vascular resistances (18.4+/-7.2 WU) were obtained from catheterization data on 40 patients with a TCPC. TCPC resistances (0.39+/-0.26 WU) were established using computational fluid dynamic simulations conducted on anatomically accurate three-dimensional models reconstructed from MRI (n=16). These parameters were used in a lumped parameter model of the SV circulation to investigate the impact of TCPC resistance on SV hemodynamics under resting and exercise conditions. A biventricular model was used for comparison. For a biventricular circulation, the cardiac output (CO) dependence on TCPC resistance was negligible (sensitivity=-0.064 l.min(-1).WU(-1)) but not for the SV circulation (sensitivity=-0.88 l.min(-1).WU(-1)). The capacity to increase CO with heart rate was also severely reduced for the SV. At a simulated heart rate of 150 beats/min, the SV patient with the highest resistance (1.08 WU) had a significantly lower increase in CO (20.5%) compared with the SV patient with the lowest resistance (50%) and normal circulation (119%). This was due to the increased afterload (+35%) and decreased preload (-12%) associated with the SV circulation. In conclusion, TCPC resistance has a significant impact on resting hemodynamics and the exercise capacity of patients with a SV physiology. 相似文献
72.
Fabio P. Nunes Vanessa L. Merker Dominique Jennings Paul A. Caruso Emmanuelle di Tomaso Alona Muzikansky Fred G. Barker II Anat Stemmer-Rachamimov Scott R. Plotkin 《PloS one》2013,8(3)
Bevacizumab treatment can result in tumor shrinkage of progressive vestibular schwannomas in some neurofibromatosis 2 (NF2) patients but its effect on meningiomas has not been defined.To determine the clinical activity of bevacizumab against NF2-related meningiomas, we measured changes in volume of meningiomas in NF2 patients who received bevacizumab for treatment of progressive vestibular schwannomas. A radiographic response was defined as a 20% decrease in tumor size by volumetric MRI analysis. In addition, we determined the expression pattern of growth factors associated with tumor angiogenesis in paraffin-embedded tissues from 26 unrelated meningiomas. A total of 48 meningiomas in 15 NF2 patients were included in this study with a median follow up time of 18 months. A volumetric radiographic response was seen in 29% of the meningiomas (14/48). Tumor shrinkage was not durable: the median duration of response was 3.7 months and the median time to progression was 15 months. There was no significant correlation between pre-treatment growth rate and meningioma response in regression models. Tissue analysis showed no correlation between tumor microvascular density and expression of VEGF pathway components. This data suggests that, in contrast to schwannomas, activation of VEGF pathway is not the primary driver of angiogenesis in meningiomas. Our results suggest that a minority of NF2-associated meningiomas shrink during bevacizumab therapy and that these responses were of short duration. These results are comparable to previous studies of bevacizumab in sporadic meningiomas. 相似文献
73.
Stefanie Nowak Antonella Di Pizio Anat Levit Masha Y. Niv Wolfgang Meyerhof Maik Behrens 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(10):2162-2173
Background
In humans, bitterness perception is mediated by ~25 bitter taste receptors present in the oral cavity. Among these receptors three, TAS2R10, TAS2R14 and TAS2R46, exhibit extraordinary wide agonist profiles and hence contribute disproportionally high to the perception of bitterness. Perhaps the most broadly tuned receptor is the TAS2R14, which may represent, because of its prominent expression in extraoral tissues, a receptor of particular importance for the physiological actions of bitter compounds beyond taste.Methods
To investigate how the architecture and composition of the TAS2R14 binding pocket enables specific interactions with a complex array of chemically diverse bitter agonists, we carried out homology modeling and ligand docking experiments, subjected the receptor to point-mutagenesis of binding site residues and performed functional calcium mobilization assays.Results
In total, 40 point-mutated receptor constructs were generated to investigate the contribution of 19 positions presumably located in the receptor's binding pocket to activation by 7 different TAS2R14 agonists. All investigated positions exhibited moderate to pronounced agonist selectivity.Conclusions
Since numerous modifications of the TAS2R14 binding pocket resulted in improved responses to individual agonists, we conclude that this bitter taste receptor might represent a suitable template for the engineering of the agonist profile of a chemoreceptive receptor.General significance
The detailed structure-function analysis of the highly promiscuous and widely expressed TAS2R14 suggests that this receptor must be considered as potentially frequent target for known and novel drugs including undesired off-effects. 相似文献74.
Shen-Ying Zhang Nathaniel E. Clark Catherine A. Freije Elodie Pauwels Allison J. Taggart Satoshi Okada Hanna Mandel Paula Garcia Michael J. Ciancanelli Anat Biran Fabien G. Lafaille Miyuki Tsumura Aurélie Cobat Jingchuan Luo Stefano Volpi Bastian Zimmer Sonoko Sakata Alexandra Dinis Jean-Laurent Casanova 《Cell》2018,172(5):952-965.e18
75.
Maria Karagkouni Spyros Sfenthourakis Anat Feldman Shai Meiri 《Journal of Zoological Systematics and Evolutionary Research》2016,54(3):182-188
This study tries to unveil the contribution of climatic shift in shaping the extreme body size diversity in terrestrial isopods (Oniscidea). Trying to explain size variation at an interspecific level, we test five hypotheses: (1) Bergmann's Rule and the temperature‐size rule postulate large size in cold areas; (2) The metabolic cold adaptation theory postulates small animal sizes in cold environments; (3) The primary productivity hypothesis predicts size increase in resource‐rich areas; (4) The aridity resistance hypothesis predicts large size in arid regions; and (5). The acidosis hypothesis predicts smaller size with decreasing soil pH. Globally, Bergmann's rule and the aridity hypothesis are weakly supported. Among families and genera, results are variable and idiosyncratic. Conglobating species sizes provide weak support for the acidosis hypothesis. Overall, size is strongly affected by familial affiliation. Isopod size evolution seems to be mainly affected by phylogenetically constrained life‐history traits. 相似文献
76.
Ezer A Matalon E Jindou S Borovok I Atamna N Yu Z Morrison M Bayer EA Lamed R 《Journal of bacteriology》2008,190(24):8220-8222
The rumen bacterium Ruminococcus albus binds to and degrades crystalline cellulosic substrates via a unique cellulose degradation system. A unique family of carbohydrate-binding modules (CBM37), located at the C terminus of different glycoside hydrolases, appears to be responsible both for anchoring these enzymes to the bacterial cell surface and for substrate binding. 相似文献
77.
78.
Celeste Weiss Anat Bonshtien Odelia Farchi-Pisanty Anna Vitlin Abdussalam Azem 《Plant molecular biology》2009,69(3):227-238
The chloroplast cpn20 protein is a functional homolog of the cpn10 co-chaperonin, but its gene consists of two cpn10-like
units joined head-to-tail by a short chain of amino acids. This double protein is unique to plastids and was shown to exist
in plants as well plastid-containing parasites. In vitro assays showed that this cpn20 co-chaperonin is a functional homolog
of cpn10. In terms of structure, existing data indicate that the oligomer is tetrameric, yet it interacts with a heptameric
cpn60 partner. Thus, the functional oligomeric structure remains a mystery. In this review, we summarize what is known about
this distinctive chaperonin and use a bioinformatics approach to examine the expression of cpn20 in Arabidopsis thaliana relative to other chaperonin genes in this species. In addition, we examine the primary structure of the two homologous domains
for similarities and differences, in comparison with cpn10 from other species. Lastly, we hypothesize as to the oligomeric
structure and raison d’être of this unusual co-chaperonin homolog.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
79.
Saher Hamed Benjamin Brenner Anat Aharon Deeb Daoud Ariel Roguin 《Cardiovascular diabetology》2009,8(1):1-12