957 resultados para TRABECULAR SHEAR-STRESS


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Abstract Background: Functional tests have limited accuracy for identifying myocardial ischemia in patients with left bundle branch block (LBBB). Objective: To assess the diagnostic accuracy of dipyridamole-stress myocardial computed tomography perfusion (CTP) by 320-detector CT in patients with LBBB using invasive quantitative coronary angiography (QCA) (stenosis ≥ 70%) as reference; to investigate the advantage of adding CTP to coronary computed tomography angiography (CTA) and compare the results with those of single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy. Methods: Thirty patients with LBBB who had undergone SPECT for the investigation of coronary artery disease were referred for stress tomography. Independent examiners performed per-patient and per-coronary territory assessments. All patients gave written informed consent to participate in the study that was approved by the institution’s ethics committee. Results: The patients’ mean age was 62 ± 10 years. The mean dose of radiation for the tomography protocol was 9.3 ± 4.6 mSv. With regard to CTP, the per-patient values for sensitivity, specificity, positive and negative predictive values, and accuracy were 86%, 81%, 80%, 87%, and 83%, respectively (p = 0.001). The per-territory values were 63%, 86%, 65%, 84%, and 79%, respectively (p < 0.001). In both analyses, the addition of CTP to CTA achieved higher diagnostic accuracy for detecting myocardial ischemia than SPECT (p < 0.001). Conclusion: The use of the stress tomography protocol is feasible and has good diagnostic accuracy for assessing myocardial ischemia in patients with LBBB.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2014

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Magdeburg, Univ., Fak. für Maschinenbau, Diss., 2015

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Otto-von-Guericke-Universität Magdeburg, Fakultät für Naturwissenschaften, Univ., Dissertation, 2015

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Drosophila willistoni (Sturtevant, 1916) is a species of the willistoni group of Drosophila having wide distribution from the South of USA (Florida) and Mexico to the North of Argentina. It has been subject of many evolutionary studies within the group, due to its considerable ability to successfully occupy a wide range of environments and also because of its great genetic variability expressed by different markers. The D. willistoni 17A2 strain was collected in 1991 in the state of Rio Grande do Sul, Brazil (30°05'S, 51°39'W), and has been maintained since then at the Drosophila laboratory of UFRGS. Different to the other D. willistoni strains maintained in the laboratory, the 17A2 strain spontaneously produced mutant males white-like (white eyes) and sepia-like (brown eyes) in stocks held at 17°C. In order to discover if this strain is potentially hypermutable, we submitted it to temperature stress tests. Eighteen isofemale strains were used in our tests and, after the first generation, all the individuals produced in each strain were maintained at 29°C. Different phenotype alterations were observed in subsequent generations, similar to mutations already well characterized in D. melanogaster (white, sepia, blistered and curly). In addition, an uncommon phenotype alteration with an apparent fusion of the antennae was observed, but only in the isofemale line nº 31. This last alteration has not been previously described as a mutation in the D. melanogaster species. Our results indicate that the D. willistoni 17A2 strain is a candidate for hypermutability, which presents considerable cryptic genetic variability. Different factors may be operating for the formation of this effect, such as the mobilization of transposable elements, effect of inbreeding and alteration of the heat-shock proteins functions.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A sample of about 70 young bulls of each of ten beef cattle breeds reared in their typical production systems has been characterised with respect to meat quality traits. Breeds included were Asturiana de los Valles, Asturiana de la Montaña, Avileña-Negra Ibérica, Bruna dels Pirineus, Morucha, Pirenaica and Retinta from Spain, and Aubrac, Gasconne and Salers from France. As was previously showed regarding carcass traits, there exist large differences both between and within breed – systems. In general, rustic breeds tended to present darker and redder meats with higher haematin contents, whereas less precocious and more specialised breeds showed brighter meats with bigger water losses. Protein content was similar, whereas intramuscular fat presented the larger variations both between and within breeds. ICDH content was higher in the more rustic breeds, showing the predominantly oxidative character of their fibres. Texture measurements showed in general large within breed-system variations, the differences between breeds being less evident. Within breed-system, daily gain weight was positively associated with brighter and tender meats. In the range studied, increasing slaughter weight within breed did not have influence on meat quality. Conformation was related to lower water holding capacity and less dry matter and intramuscular fat, as well as to a lower haematin content giving brighter meats. The increase in fatness scores was related to an augment of toughness in meat specialised breeds, although in Avileña-Negra Ibérica breed fatness carcasses were related to more tender meats. Redness parameter a* was positively related to fatter animals and opposed to conformation, the opposite being true for the L* (lightness) parameter. There was a small trend of fatter carcasses to be related to oxidative fibres, whereas the muscular fibres of the more conformed carcasses were more glycolytic. Texture measurements maximum load, maximum stress and toughness were very closely related. Shear force was opposed to tenderness. Losses at cooking were opposed to juiciness, but only in the Spanish breeds. No consistent trends regarding relationships between carcass characteristics and tenderness could be observed. Overall acceptability was primarily related with tenderness and flavour, and later on juiciness.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A role for the gastro-intestinal tract in controlling bone remodeling is suspected since serum levels of bone remodeling markers are affected rapidly after a meal. Glucose-dependent insulinotropic polypeptide (GIP) represents a suitable candidate in mediating this effect. The aim of the present study was to investigate the effect of total inhibition of GIP signaling on trabecular bone volume, microarchitecture and quality. We used GIP receptor (GIPR) knockout mice and investigated trabecular bone volume and microarchitecture by microCT and histomorphometry. GIPR-deficient animals at 16 weeks of age presented with a significant (20%) increase in trabecular bone mass accompanied by an increase (17%) in trabecular number. In addition, the number of osteoclasts and bone formation rate was significantly reduced and augmented, respectively in these animals when compared with wild-type littermates. These modifications of trabecular bone microarchitecture are linked to a remodeling in the expression pattern of adipokines in the GIPR-deficient mice. On the other hand, despite significant enhancement in bone volume, intrinsic mechanical properties of the bone matrix was reduced as well as the distribution of bone mineral density and the ratio of mature/immature collagen cross-links. Taken together, these results indicate an increase in trabecular bone volume in GIPR KO animals associated with a reduction in bone quality.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Background/Purpose: The trabecular bone score (TBS), a novel graylevel texture index determined from lumbar spine DXA scans, correlates with 3D parameters of trabecular bone microarchitecture known to predict fracture. TBS may enhance the identification of patients at increased risk for vertebral fracture independently of bone mineral density (BMD) (Boutroy JBMR 2010; Hans JBMR 2011). Denosumab treatment for 36 months decreased bone turnover, increased BMD, and reduced new vertebral fractures in postmenopausal women with osteoporosis (Cummings NEJM 2009). We explored the effect of denosumab on TBS over 36 months and evaluated the association between TBS and lumbar spine BMD in women who had DXA scans obtained from eligible scanners for TBS evaluation in FREEDOM. Methods: FREEDOM was a 3-year, randomized, double-blind trial that enrolled postmenopausal women with a lumbar spine or total hip DXA T-score __2.5, but not __4.0 at both sites. Women received placebo or 60 mg denosumab every 6 months. A subset of women in FREEDOM participated in a DXA substudy where lumbar spine DXA scans were obtained at baseline and months 1, 6, 12, 24, and 36. We retrospectively applied, in a blinded-to-treatment manner, a novel software program (TBS iNsightR v1.9, Med-Imaps, Pessac, France) to the standard lumbar spine DXA scans obtained in these women to determine their TBS indices at baseline and months 12, 24, and 36. From previous studies, a TBS _1.35 is considered as normal microarchitecture, a TBS between 1.35 and _1.20 as partially deteriorated, and 1.20 reflects degraded microarchitecture. Results: There were 285 women (128 placebo, 157 denosumab) with a TBS value at baseline and _1 post-baseline visit. Their mean age was 73, their mean lumbar spine BMD T-score was _2.79, and their mean lumbar spine TBS was 1.20. In addition to the robust gains in DXA lumbar spine BMD observed with denosumab (9.8% at month 36), there were consistent, progressive, and significant increases in TBS compared with placebo and baseline (Table & Figure). BMD explained a very small fraction of the variance in TBS at baseline (r2_0.07). In addition, the variance in the TBS change was largely unrelated to BMD change, whether expressed in absolute or percentage changes, regardless of treatment, throughout the study (all r2_0.06); indicating that TBS provides distinct information, independently of BMD. Conclusion: In postmenopausal women with osteoporosis, denosumab significantly improved TBS, an index of lumbar spine trabecular microarchitecture, independently of BMD.