944 resultados para computational fluid dynamic
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This study was conducted to determine the effect of pre-exposure of oocytes to Ricinus communis (RCA-1) lectin and osteopontin (OPN) in uterine tube fluid (UTF) on in vitro sperm-egg binding and fertilization. In vitro-matured bovine oocytes were incubated (39 degrees C, 5% CO(2) in air) for 2 h in the following treatments: (i) 500 mu l of fertilization medium (FM); (ii) 250 mu l of FM with 0.25 ml of non-luteal ampullary uterine tube fluid (NLAUTF); (iii) 250 mu l of FM with 250 mu l of NLAUTF and 4 mu l of RCA-1 lectin; (iv) 250 mu l of FM with 250 mu l of NLAUTF, a rabbit polyclonal antibody (1:200) against purified bovine milk OPN, and RCA-1 lectin; (v) 500 mu l of FM and RCA-1 lectin. Following incubation, oocytes were washed, placed in FM with 2 mu g heparin, and incubated with 1 x 10(5) frozen-thawed spermatozoa per 10 oocytes. Oocytes used to assess sperm binding were stained with Hoescht 33342, and the number of sperm bound per zona pellucida counted. The remaining oocytes were fixed in acid alcohol, stained with 1% acetate-orcein and observed to determine the presence of pronuclei. More sperm bound to the zona pellucida (mean +/- SEM) when oocytes were incubated in treatment 3 (59.0 +/- 5.5) than in treatments 2 (46.4 +/- 5.6), 4 (18.1 +/- 5.4), 5 (33.4 +/- 5.6) or 1 (32.5 +/- 5.6). More oocytes were fertilized when incubated in treatment 3 (91% +/- 3.0) than in 2 (84% +/- 3.0), 4 (40% +/- 3.0), 5 (77% +/- 3.0) or 1 (76% +/- 3.0). As in previous studies, this study suggests that RCA-1 lectin enhances binding of UTF-derived OPN to bovine oocytes, resulting in increased sperm-egg binding and fertilization in vitro and a possible role in fertilization.
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Studies have demonstrated that oviductal fluid (ODF) proteins associate with eggs of numerous species including the bovine. In this study, the association of three ODF proteins, the bovine oestrus-associated protein, osteopontin (OPN), lipocalin-type prostaglandin D synthase (L-PGDS), with the bovine zona pellucida (ZP) was demonstrated by immunohistochemistry and western blot. The biological function of ODF derived egg-associated OPN and L-PGDS in sperm binding, fertilization and embryonic development was also explored. In vitro matured bovine oocytes were pre-incubated with ODF collected by cannula from cows in oestrus, or ODF with antibodies to OPN, L-PGDS and bovine serum albumin (BSA). Following incubation, oocytes were inseminated with 1 x 10(5) frozen-thawed spermatozoa, and they were evaluated for sperm binding, fertilization and embryonic development in vitro. Pre-treatment of ODF with antibodies to all of proteins reduced sperm binding to the ZP and fertilization in vitro. Cleavage rates were not significantly different among incubations, but rates of embryo development were significantly decreased. We conclude that antibodies to OPN, L-PGDS and BSA react with oocytes incubated with ODF and inhibit sperm binding, fertilization and embryonic development in vitro, suggesting a potential role of these proteins in these events.
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Reports experimental results involving 204 members of the public who were asked their willingness to pay for the conservation of the mahogany glider Petaurus gracilis on three occasions: prior to information being provided to them about the glider and other wildlife species; after such information was provided, and after participants had an opportunity to see live specimens of this endangered species. Variations in the mean willingness to pay are analysed. Concerns arise about whether information provision and experience reveal ‘true’ contingent valuations of public goods and about the choice of the relevant contingent valuation measure.
Gingival crevicular fluid levels of MMP-8, MMP-9, TIMP-2, and MPO decrease after periodontal therapy
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P>Background This study aimed at comparing the levels of matrix metalloproteinase (MMP)-8, tissue Inhibitor of MMPs (TIMP)-1 and TIMP-2, Myeloperoxidase (MPO), and MMP-9 in the gingival crevicular fluid (GCF) of chronic periodontitis (CP) patients and controls at baseline and 3 months after non-surgical therapy. Materials and Methods GCF was collected from one site of 15 control subjects and 27 CP patients. MMP-8, MMP-9, TIMP-1, and TIMP-2 were determined by Enzyme-linked immunoabsorbent assay; different forms of MMP-9, by gelatin zymography; and MPO, colorimetrically. Results At baseline, higher levels of MMP-8, TIMP-2, MPO, and the 87 kDa-MMP-9 were found in patients compared with controls (p < 0.001), and these molecules decreased after therapy (p < 0.03). There were no differences between the groups with respect to the higher molecular forms of MMP-9 (180, 130, 92 kDa) or total MMP-9 at baseline. No differences were observed in TIMP-1 levels. In controls, decreased levels of TIMP-2 and the higher molecular forms of MMP-9 (180, 130, 92 kDa) were found 3 months after therapy compared with baseline (p < 0.01). Conclusions Higher levels of MMP-8, TIMP-2, MPO, and 87 kDa MMP-9 were found in the GCF of patients compared with controls, and these markers decreased 3 months after periodontal therapy.
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A question is examined as to estimates of the norms of perturbations of a linear stable dynamic system, under which the perturbed system remains stable in a situation R:here a perturbation has a fixed structure.
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Epstein–Barr virus (EBV) encephalitis has been reported rarely in the context of solid-organ and bone-marrow transplantation [1]. We report a case of a renal transplant recipient who developed EBV encephalitis following OKT3 therapy for acute allograft rejection. The diagnosis was expedited by the detection of EBV DNA in the cerebrospinal fluid (CSF) by nested polymerase chain reaction (PCR). Moreover, clinical recovery and clearance of CSF EBV DNA appeared to follow the institution of parenteral ganciclovir treatment.
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A dynamic modelling methodology, which combines on-line variable estimation and parameter identification with physical laws to form an adaptive model for rotary sugar drying processes, is developed in this paper. In contrast to the conventional rate-based models using empirical transfer coefficients, the heat and mass transfer rates are estimated by using on-line measurements in the new model. Furthermore, a set of improved sectional solid transport equations with localized parameters is developed in this work to reidentified on-line using measurement data, the model is able to closely track the dynamic behaviour of rotary drying processes within a broad range of operational conditions. This adaptive model is validated against experimental data obtained from a pilot-scale rotary sugar dryer. The proposed modelling methodology can be easily incorporated into nonlinear model based control schemes to form a unified modelling and control framework.place the global correlation for the computation of solid retention time. Since a number of key model variables and parameters are identified on-line using measurement data, the model is able to closely track the dynamic behaviour of rotary drying processes within a broad range of operational conditions. This adaptive model is validated against experimental data obtained from a pilot-scale rotary sugar dryer. The proposed modelling methodology can be easily incorporated into nonlinear model based control schemes to form a unified modelling and control framework.
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Background Icodextrin is a high molecular weight, starch-derived glucose polymer, which is capable of inducing sustained ultrafiltration over prolonged (12–16 hour) peritoneal dialysis (PD) dwells. The aim of this study was to evaluate the ability of icodextrin to alleviate refractory, symptomatic fluid overload and prolong technique survival in PD patients. Methods A prospective, open-label, pre-test/post-test study was conducted in 17 PD patients (8 females/9 males, mean age 56.8 ± 2.9 years) who were on the verge of being transferred to haemodialysis because of symptomatic fluid retention that was refractory to fluid restriction, loop diuretic therapy, hypertonic glucose exchanges and dwell time optimisation. One icodextrin exchange (2.5 L 7.5%, 12-hour dwell) was substituted for a long-dwell glucose exchange each day. Results Icodextrin significantly increased peritoneal ultrafiltration (885 ± 210 ml to 1454 ± 215 ml, p < 0.05) and reduced mean arterial pressure (106 ± 4 to 96 ± 4 mmHg, p < 0.05), but did not affect weight, plasma albumin concentration, haemoglobin levels or dialysate:plasma creatinine ratio. Diabetic patients (n = 12) also experienced improved glycaemic control (haemoglobin Alc decreased from 8.9 ± 0.7% to 7.9 ± 0.7%, p < 0.05). Overall PD technique survival was prolonged by a mean of 11.6 months (95% CI 6.0–17.3 months). On multivariate Cox proportional hazards analysis, extension of technique survival by icodextrin was only significantly predicted by baseline net daily peritoneal ultrafiltration (adjusted HR 2.52, 95% CI 1.13–5.62, p < 0.05). Conclusions Icodextrin significantly improved peritoneal ultrafiltration and extended technique survival in PD patients with symptomatic fluid overload, especially those who had substantially impaired peritoneal ultrafiltration.
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Purpose: This study was designed to investigate the immediate effect of exercise intensity and duration on body fluid volumes in rats throughout a 3-wk exercise program. Methods: Changes in the extracellular water (ECW) and total body water (TBW) volumes of rats were measured preexercise and postexercise using multiple frequency bioelectrical impedance analysis. Groups of rats were exercised at two intensities (6 m.min(-1) and 12 m.min(-1)) for two exercise times (60 min and 90 min) 5 d.wk(-1) during a 3-wk period. Changes in plasma electrolytes, glucose, and lactate resulting from the exercise were also measured on 3 d of each week. Results: Each group of animals showed significant losses in ECW and TBW as a direct result of daily exercise. The magnitude of fluid loss was directly related to the intensity of the exercise, bur not to exercise duration; although the magnitude of daily fluid loss at the higher intensity exercise (12 m.min(-1)) decreased as the study progressed, possibly indicating a training effect. Conclusion: At low-intensity exercise, there is a small bur significant loss in both TBW and ECW fluids, and the magnitude of these losses does not change throughout a 3-wk exercise program. At moderate levels of exercise intensity, there is a greater loss of both TBW and ECW fluids. However, the magnitudes of these losses decrease significantly during the 3-wk exercise program, thus demonstrating a training effect.
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In this paper a methodology for integrated multivariate monitoring and control of biological wastewater treatment plants during extreme events is presented. To monitor the process, on-line dynamic principal component analysis (PCA) is performed on the process data to extract the principal components that represent the underlying mechanisms of the process. Fuzzy c-means (FCM) clustering is used to classify the operational state. Performing clustering on scores from PCA solves computational problems as well as increases robustness due to noise attenuation. The class-membership information from FCM is used to derive adequate control set points for the local control loops. The methodology is illustrated by a simulation study of a biological wastewater treatment plant, on which disturbances of various types are imposed. The results show that the methodology can be used to determine and co-ordinate control actions in order to shift the control objective and improve the effluent quality.
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The overlapping expression profile of MEF2 and the class-II histone deacetylase, HDAC7, led us to investigate the functional interaction and relationship between these regulatory proteins. HDAC7 expression inhibits the activity of MEF2 (-A, -C, and -D), and in contrast MyoD and Myogenin activities are not affected. Glutathione S-transferase pulldown and immunoprecipitation demonstrate that the repression mechanism involves direct interactions between MEF2 proteins and HDAC7 and is associated with the ability of MEF2 to interact with the N-terminal 121 amino acids of HDAC7 that encode repression domain 1. The MADS domain of MEF2 mediates the direct interaction of MEF2 with HDAC7, MEF2 inhibition by HDAC7 is dependent on the N-terminal repression domain and surprisingly does not involve the C-terminal deacetylase domain. HDAC7 interacts with CtBP and other class-I and -II HDACs suggesting that silencing of MEF2 activity involves corepressor recruitment. Furthermore, we show that induction of muscle differentiation by serum withdrawal leads to the translocation of HDAC7 from the nucleus into the cytoplasm. This work demonstrates that HDAC7 regulates the function of MEF2 proteins and suggests that this class-II HDAC regulates this important transcriptional (and pathophysiological) target in heart and muscle tissue. The nucleocytoplasmic trafficking of HDAC7 and other class-II HDACs during myogenesis provides an ideal mechanism for the regulation of HDAC targets during mammalian development and differentiation.
The acquisition of movement skills: Practice enhances the dynamic stability of bimanual coordination
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During bimanual movements, two relatively stable inherent patterns of coordination (in-phase and anti-phase) are displayed (e.g., Kelso, Am. J. Physiol. 246 (1984) R1000). Recent research has shown that new patterns of coordination can be learned. For example, following practice a 90 degrees out-of-phase pattern can emerge as an additional, relatively stable, state (e.g., Zanone & Kelso, J. Exp. Psychol.: Human Performance and Perception 18 (1992) 403). On this basis, it has been concluded that practice leads to the evolution and stabilisation of the newly learned pattern and that this process of learning changes the entire attractor layout of the dynamic system. A general feature of such research has been to observe the changes of the targeted pattern's stability characteristics during training at a single movement frequency. The present study was designed to examine how practice affects the maintenance of a coordinated pattern as the movement frequency is scaled. Eleven volunteers were asked to perform a bimanual forearm pronation-supination task. Time to transition onset was used as an index of the subjects' ability to maintain two symmetrically opposite coordinated patterns (target task - 90 degrees out-of-phase - transfer task - 270 degrees out-of-phase). Their ability to maintain the target task and the transfer task were examined again after five practice sessions each consisting of 15 trials of only the 90 degrees out-of-phase pattern. Concurrent performance feedback (a Lissajous figure) was available to the participants during each practice trial. A comparison of the time to transition onset showed that the target task was more stable after practice (p = 0.025). These changes were still observed one week (p = 0.05) and two months (p = 0.075) after the practice period. Changes in the stability of the transfer task were not observed until two months after practice (p = 0.025). Notably, following practice, transitions from the 90 degrees pattern were generally to the anti-phase (180 degrees) pattern, whereas, transitions from the 270 degrees pattern were to the 90 degrees pattern. These results suggest that practice does improve the stability of a 90 degrees pattern, and that such improvements are transferable to the performance of the unpractised 270 degrees pattern. In addition, the anti-phase pattern remained more stable than the practised 90 degrees pattern throughout. (C) 2001 Elsevier Science B.V. All rights reserved.