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排序方式: 共有2221条查询结果,搜索用时 15 毫秒
91.
Pablo Lozano Marta Pea Mariano Herrero-Climent Jose Vicente Rios-Santos Blanca Rios-Carrasco Aritza Brizuela Javier Gil 《Materials》2022,15(4)
The procedure generally used to remove bacterial biofilm adhering to the surface of titanium on dental implants is implantoplasty. This treatment is based on the machining of the titanium surface to remove bacterial plaque. In this study, we used 60 grade 4 titanium implants and performed the implantoplasty protocol. Using X-ray diffraction, we determined the stresses accumulated in each of the as-received, machined and debris implants. The resistance to corrosion in open circuit and potentiodynamically in physiological medium has been determined, and the corrosion potentials and intensities have been determined. Tests have been carried out to determine ion release by ICP-MS at different immersion times. The results show that the corrosion resistance and the release of titanium ions into the medium are related to the accumulated energy or the degree of deformation. The titanium debris exhibit compressive residual stresses of −202 MPa, the implant treated with implantoplasty −120 MPa, and as-received −77 MPa, with their corrosion behavior resulting in corrosion rates of 0.501, 0.77, and 0.444 mm/year, respectively. Debris is the material with the worst corrosion resistance and the one that releases the most titanium ions to the physiological medium (15.3 ppb after 21 days vs. 7 ppb for as-received samples). Pitting has been observed on the surface of the debris released into the physiological environment. This behavior should be taken into account by clinicians for the good long-term behavior of implants with implantoplasty. 相似文献
92.
Galindo BE Vacquier VD Swanson WJ 《Proceedings of the National Academy of Sciences of the United States of America》2003,100(8):4639-4643
The mechanism of speciation is a central problem in evolutionary biology. In free-spawning animals with no complex mating behavior, prezygotic reproductive isolation (speciation) could result from the rapid divergence of genes coding for sperm and egg proteins that bind each other during fertilization. In abalone, sperm lysin evolves rapidly by positive Darwinian selection. The egg vitelline envelope receptor for lysin had previously been shown to evolve neutrally and be subjected to concerted evolution. Several mathematical simulations predict that both male and female reproductive proteins should evolve rapidly by positive selection. Here we report that the sequence diversity of the amino-terminal end of the egg vitelline envelope receptor for lysin has been promoted by positive Darwinian selection. These data provide molecular support for theoretical models showing that the two sexes are locked in a "coevolutionary chase" that could be driven by processes such as sexual selection, sexual conflict, or microbial attack (pathogen avoidance). The result of this continuous coevolution of the gamete recognition system could be the splitting of one population into two that are reproductively isolated (speciation). 相似文献
93.
The multiscale time irreversibility (MTI) involves the lack of consistency in the properties of a time series if one reverses the reading direction along the time. To analyze the RR time series at rest and during aerobic exercise through the MTI, both in healthy people and cardiac patients. The heartbeat signal was recorded beat to beat for 15 min at rest and 15 min while pedalling on a static bicycle in 10 healthy and active men (age 26.5 ± 3.3 years; height 179.3 ± 6.6 cm; weight 80.4 ± 11.8 kg) and 10 cardiac patients (age 61.1 ± 4.7 years, height 165.3 ± 5.3 cm; weight 86.9 ± 11.1 kg). The MTI was calculated through the asymmetry index (AI), defined as the sum of the values of asymmetry obtained for each scale from 1 to 10. The AI decreases significantly in healthy subjects from 0.51 ± 0.28 at rest to 0.28 ± 0.24 during exercise (P = 0.01) but not in cardiac patients (?0.2204 ± 0.5097 at rest and 0.0848 ± 0.1200 during exercise; P = 0.07). MTI distinguish adequately the four experimental situations because it can be considered as an index of the internal property of the signal in contrast to linear methods which are highly sensitive to external influences over the heart rhythm, particularly sympathetic and parasympathetic stimuli. 相似文献
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Blanca Rueda Concepción Núñez Miguel Á. López-Nevot Ma Paz Ruiz Elena Urcelay Emilio G. De La Concha 《Scandinavian journal of gastroenterology》2013,48(4):420-423
Abstract Objective. There is a discrepancy between clinical activity and biomarkers in inflammatory bowel disease. The Harvey–Bradshaw index (HBi) is steadfast to evaluate disease activity. A set of biological markers (high sensitive C-reactive protein [hs-CRP], calprotectin, total nitrite, soluble urokinase Plasminogen Activator Receptor [suPAR], ghrelin and endothelin) are investigated to study inflammatory activity and correlation with HBi during infliximab therapy. Material and methods. Patients with Crohn'sdisease (n = 22) were assessed and blood samples drawn before and 1 week after infliximab infusion (5 mg/kg) and repeated after 6 months, and compared to healthy volunteers. Hs-CRP, calprotectin, suPAR, ghrelin and endothelin were analyzed with immunoassays, and total nitrite with Griess-reaction. Results were analyzed with Wilcoxon matched-pairs test, Mann–Whitney test and Spearman correlations. Results. After the first infusion visit, HBi and calprotectin values decreased while nitrite increased (p < 0.05). At the 6-month visit, pre-infusion index and biomarkers had returned to baseline levels. Post-infusion, again the values of HBi, hs-CRP and calprotectin decreased (p < 0.05). The suPAR levels did not change between pre- and post-infusion periods at either visit. Calprotectin, nitrite and suPAR differed from healthy controls throughout the study (p < 0.05). Endothelin decreased with each treatment but was, like ghrelin, not different from controls. We found HBi to correlate with hs-CRP (Spearman r = 0.32, p < 0.05), but calprotectin did not, neither did nitrate nor suPAR. Conclusions. Although infliximab ameliorates Crohn'sdisease symptoms, inflammatory markers are not persistently normalized, indicating a chronic inflammatory condition that may require continued infliximab therapy. 相似文献
97.
Liang Dong Shu-Juan Wang Blanca Camoretti-Mercado Hong-Jia Li Ming Chen Wen-Xiang Bi 《The Journal of asthma》2013,50(8):648-653
The aim of this study was to elucidate the role of Found in Inflammatory Zone 1 (FIZZ1, also known as RELM-α or resistin-like molecule-α) in airway remodeling in asthma. We used a rat model of ovalbumin (OVA) sensitization and challenge to induce lung inflammation and remodeling. Expression of α -SMA in the lungs of OVA-treated rats was significantly elevated in the peribronchial regions compared with control saline-treated animals. Expression of FIZZ1 mRNA in alveolar epithelial type II cells (AECII) isolated from OVA-treated animals was higher than in control animals. Forced expression of recombinant FIZZ1 in rat-1 lung fibroblast cell line enhanced production of collagen type I and α -SMA compared with control transfected cells. These results suggest that FIZZ1 can induce fibroblasts to express markers of myofibroblast differentiation such as α -SMA and collagen type I, which are characteristic of early stages of airway remodeling seen in asthma. 相似文献
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Antonio Sánchez Blanca Cantos Pilar España Clara Salas Mariano Provencio 《Clinical & translational oncology》2008,10(7):439-441
Hodgkin's disease (HD) is an example of a curable disease. In addition, it can serve as a lesson about other pathologies because of the delayed side effects it produces and the appearance of associated processes that may simulate disease progression. Here we provide a case report of a patient who encapsulates a compendium of situations that may occur in HD. 相似文献