Search results for "STRESS"
showing 10 items of 6278 documents
Incremental elastoplastic analysis for active macro-zones
2012
In this paper a strategy to perform incremental elastoplastic analysis using the symmetric Galerkin boundary element method for multidomain type problems is shown. The discretization of the body is performed through substructures, distinguishing the bem-elements characterizing the so-called active macro-zones, where the plastic consistency condition may be violated, and the macro-elements having elastic behaviour only. Incremental analysis uses the well-known concept of self-equilibrium stress field here shown in a discrete form through the introduction of the influence matrix (self-stress matrix). The nonlinear analysis does not use updating of the elastic response inside each plastic loop…
Conceptualizing ecosystem tipping points within a physiological framework
2017
Connecting the nonlinear and often counterintuitive physiological effects of multiple environmental drivers to the emergent impacts on ecosystems is a fundamental challenge. Unfortunately, the disconnect between the way “stressors” (e.g., warming) is considered in organismal (physiological) and ecological (community) contexts continues to hamper progress. Environmental drivers typically elicit biphasic physiological responses, where performance declines at levels above and below some optimum. It is also well understood that species exhibit highly variable response surfaces to these changes so that the optimum level of any environmental driver can vary among interacting species. Thus, specie…
Tolerance, Adaptation, and Cell Response Elicited by Micromonospora sp. Facing Tellurite Toxicity: A Biological and Physical-Chemical Characterization
2022
The intense use of tellurium (Te) in industrial applications, along with the improper disposal of Te-derivatives, is causing their accumulation in the environment, where oxyanion tellurite (TeO32−) is the most soluble, bioavailable, and toxic Te-species. On the other hand, tellurium is a rare metalloid element whose natural supply will end shortly with possible economic and technological effects. Thus, Te-containing waste represents the source from which Te should be recycled and recovered. Among the explored strategies, the microbial TeO32− biotransformation into less toxic Te-species is the most appropriate concerning the circular economy. Actinomycetes are ideal candidates in…
Conseguenze metaboliche dell'ipossia
2011
Riassunto La sopravvivenza in condizioni di ipossia dipende dall’attivazione di processi cellulari complessi, con risposte di adattamento (quali il potenziamento del trasporto di O2 attraverso l’aumento dell’eritropoiesi, l’attivazione dell’angiogenesi e l’aumento della glicolisi anaerobica) e l’inibizione di processi metabolici che richiedono alta disponibilità di O2. Ciò consente di mantenere l’omeostasi energetica anche in condizioni di ridotta disponibilità di O2. Nel modello fisiologico del soggiorno ad alta quota si verificano riduzione di peso e della capacità di lavoro associata a riduzione della massa muscolare, che però sono reversibili al ripristino di condizioni di normossia. Le…
Comparison of the acute effects of anti-TNF-alpha drugs on a uveitis experimental model.
2010
To compare histopathological and biochemical effects of the anti-TNF-alpha drugs adalimumab and infliximab in a uveitis experimental model.Histopathological evaluation was performed 24 h after endotoxin (200 microg into the footpad) and drug administration, as well as biochemical analysis of oxidative stress-related markers in the aqueous humor.Severe inflammation was found in rat anterior chamber of the eye 24 h after endotoxin. Only infliximab administration partially prevented the endotoxin-induced disruption of the blood-aqueous barrier, as well as the increase in Rantes and MCP-1 concentration in aqueous humor. Both drugs ameliorated the histopathological score after endotoxin. Biochem…
Psychological variables and temporomandibular disorders: distress, coping, and personality.
2004
Abstract Objective This study analyzes the psychological variables of distress, personality, and coping that are related to the diagnosis based on the Research Diagnostic Criteria for temporomandibular disorder. Study design An age and sex-matched controlled study conducted with a convenience sample (n = 89) in a tertiary care facility. Results The MANCOVA between the muscular (n = 47), articular (n = 42), and control groups (n = 100) showed that the muscular group differed from the control group, obtaining higher levels of distress, anxiety, and depression, and minor use of positive reinterpretation and humor as coping strategies; the articular group also showed higher distress, less posit…
Effect of lumbar disc replacement on the height of the disc space and the geometry of the facet joints: a cadaver study.
2010
In a study on ten fresh human cadavers we examined the change in the height of the intervertebral disc space, the angle of lordosis and the geometry of the facet joints after insertion of intervertebral total disc replacements. SB III Charité prostheses were inserted at L3-4, L4-5, and L5-S1. The changes studied were measured using computer navigation sofware applied to CT scans before and after instrumentation. After disc replacement the mean lumbar disc height was doubled (p < 0.001). The mean angle of lordosis and the facet joint space increased by a statistically significant extent (p < 0.005 and p = 0.006, respectively). By contrast, the mean facet joint overlap was significantl…
Physiological incongruity of the humero-ulnar joint: a functional principle of optimized stress distribution acting upon articulating surfaces?
1993
Investigations into the distribution of subchondral bone density in the human elbow have suggested that the geometry of the trochlear notch deviates from a perfect fit with the trochlea, and that the load is transmitted ventrally and dorsally rather than through the centre of the humero-ulnar joint. We therefore decided to make a quantitative assessment of the degree of incongruity between the two components in 15 human specimens (age distribution 60 to 93 years) with different types of joint surface. Polyether casts of the joint cavity were prepared under loads of 10, 40, 160 and 640 N. The thickness of the casts was then measured at 50 predetermined points, and an area distribution of the…
Osteogenic differentiation of periodontal fibroblasts is dependent on the strength of mechanical strain
2012
Abstract Objective During orthodontic therapy the correct strength of mechanical strain plays a key role for bone remodelling during tooth movement. Aim of this study was to investigate the osteogenic differentiation of human periodontal ligament fibroblasts (HPdLF) depending on the applied strength of mechanical strain compared to osteoblasts (HOB). Design HPdLF and HOB were loaded with different strengths (1%, 5% and 10%) of static mechanical strain (SMS) for 12 h in vitro. Viability was verified by MTT and apoptosis by TUNEL assay. Gene expression of cyclin D1, collagen type-1 (COL-I), alkaline phosphatase (ALP), osteocalcin, osteoprotegerin (OPG) and receptor activator of the NF-κB liga…
Deficiency of Nrf2 accelerates the effector phase of arthritis and aggravates joint disease
2011
14 páginas, 8 figuras, 1 tabla.-- et al.