946 resultados para Incompressible fluid


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PURPOSE Continuous intraoperative norepinephrine infusion combined with restrictive deferred hydration improves surgical field visibility, and significantly decreases intraoperative blood loss and postoperative complications in patients undergoing radical cystectomy and urinary diversion. We determined whether the intraoperative fluid regimen would affect functional results (continence and erectile function) 1 year after orthotopic ileal bladder substitution. MATERIALS AND METHODS We analyzed a subgroup of 93 patients who received an ileal orthotopic bladder substitute. The subgroup was part of a randomized trial in 167 patients initially allocated to continuous norepinephrine administration starting with 2 μg/kg per hour combined with 1 ml/kg per hour initially and 3 ml/kg per hour crystalloid infusion after cystectomy (norepinephrine/low volume group of 51) or a standard crystalloid infusion of 6 ml/kg per hour throughout surgery (42 controls). We prospectively assessed daytime and nighttime continence, and erectile function 1 year postoperatively in the 93-patient subgroup. RESULTS Daytime continence was reported by 44 of 51 patients (86%) in the norepinephrine/low volume group and by 27 of 42 controls (64%) (p = 0.016), and nighttime continence was reported by 38 (75%) and 25 (60%), respectively (p = 0.077). Erectile function recovery was reported by 26 of 33 preoperatively potent patients (79%) in the norepinephrine/low volume group and by 11 of 29 controls (38%) (p = 0.002). CONCLUSIONS Patients who undergo radical cystectomy and orthotopic bladder substitution with continuous norepinephrine infusion and restrictive hydration during surgery have significantly better daytime continence and erectile function 1 year postoperatively.

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Ketamine and norketamine are being transported across the blood brain barrier and are also entering from blood into cerebrospinal fluid (CSF). Enantioselective distributions of these compounds in brain and CSF have never been determined. The enantioselective CE based assay previously developed for equine plasma was adapted to the analysis of these compounds in equine brain via use of an acidic pre-extraction of interferences prior to liquid/liquid extraction at alkaline pH. CSF can be treated as plasma. With 100 mg of brain tissue and 0.5 mL of CSF or plasma, assay conditions for up to 30 nmol/g and 6 μM, respectively, of each enantiomer with LOQs of 0.5 nmol/g and 0.1 μM, respectively, were established and the assays were applied to equine samples. CSF and plasma samples analyzed stemmed from anesthetized patient horses and brain, CSF and plasma were obtained from anesthetized horses that were euthanized with an overdose of pentobarbital. Data obtained indicate that ketamine and norketamine enantiomers are penetrating into brain and CSF with those of ketamine being more favorably transported than norketamine, whereas metabolites of norketamine are hindered. More work is required to properly investigate possible stereoselectivities of the ketamine metabolism and transport of metabolites from blood into brain tissue and CSF.

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Many end-stage heart failure patients are not eligible to undergo heart transplantation due to organ shortage, and even those under consideration for transplantation might suffer long waiting periods. A better understanding of the hemodynamic impact of left ventricular assist devices (LVAD) on the cardiovascular system is therefore of great interest. Computational fluid dynamics (CFD) simulations give the opportunity to study the hemodynamics in this patient population using clinical imaging data such as computed tomographic angiography. This article reviews a recent study series involving patients with pulsatile and constant-flow LVAD devices in which CFD simulations were used to qualitatively and quantitatively assess blood flow dynamics in the thoracic aorta, demonstrating its potential to enhance the information available from medical imaging.

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PURPOSE To compare postoperative morphological and rheological conditions after eversion carotid endarterectomy versus conventional carotid endarterectomy using computational fluid dynamics. BASIC METHODS Hemodynamic metrics (velocity, wall shear stress, time-averaged wall shear stress and temporal gradient wall shear stress) in the carotid arteries were simulated in one patient after conventional carotid endarterectomy and one patient after eversion carotid endarterectomy by computational fluid dynamics analysis based on patient specific data. PRINCIPAL FINDINGS Systolic peak of the eversion carotid endarterectomy model showed a gradually decreased pressure along the stream path, the conventional carotid endarterectomy model revealed high pressure (about 180 Pa) at the carotid bulb. Regions of low wall shear stress in the conventional carotid endarterectomy model were much larger than that in the eversion carotid endarterectomy model and with lower time-averaged wall shear stress values (conventional carotid endarterectomy: 0.03-5.46 Pa vs. eversion carotid endarterectomy: 0.12-5.22 Pa). CONCLUSIONS Computational fluid dynamics after conventional carotid endarterectomy and eversion carotid endarterectomy disclosed differences in hemodynamic patterns. Larger studies are necessary to assess whether these differences are consistent and might explain different rates of restenosis in both techniques.

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The exposed Glarus thrust displays midcrustal deformation with tens of kilometers of displacement on an ultrathin layer, the principal slip zone (PSZ). Geological observations indicate that this structure resulted from repeated stick-slip events in the presence of highly overpressured fluids. Here we show that the major characteristics of the Glarus thrust movement (localization, periodicity, and evidence of pressurized fluids) can be reconciled by the coupling of two processes, namely, shear heating and fluid release by carbonate decomposition. During this coupling, slow ductile creep deformation raises the temperature through shear heating and ultimately activates the chemical decomposition of carbonates. The subsequent release of highly overpressurized fluids forms and lubricates the PSZ, allowing a ductile fault to move tens of kilometers on millimeter-thick bands in episodic stick-slip events. This model identifies carbonate decomposition as a key process for motion on the Glarus thrust and explains the source of overpressured fluids accessing the PSZ.

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Throughout follicular growth the number of immune cells increases, enhanced under stimulation with exogenous gonadotropins. This treatment, however, may adversely influence folliculogenesis and negatively affect oocyte quality through modifications in the follicular concentrations of cytokines released by these immune cells. We studied this hypothesis by systematically analysing the concentrations of cytokines present in the serum and follicular fluid at the time of follicular aspiration in conventional gonadotropin-stimulated (c-IVF) cycles in comparison with natural cycle IVF (NC-IVF) in which the follicles were naturally matured. Our study involved 37 NC-IVF and 39 c-IVF cycles including 13 women who underwent both therapies. Mean age was 35.3 ± 4.6 (SD) and 34.2 ± 3.7 years in the NC-IVF and c-IVF groups (ns). Thirteen cytokines were determined in matched serum and FF samples. Interleukin (IL)-4, TNF-α, RANTES, eotaxin and interferon-gamma-induced protein-10 concentrations were lower in FF than in serum. IL-6, -8, -10, -18, monocyte chemotactic protein-1 (MCP-1), VEGF and leukaemia inhibitory factor (LIF) showed higher median levels in FF than in serum, indicating possible ovarian production. Most of these markers were also increased in concentration in the stimulated (c-IVF) than in the NC groups in the serum, but not in the follicular fluid. This finding can be attributed to the increased number of active follicles present after controlled ovarian stimulation. IL-8 was reduced in c-IVF cycles. Our study did not reveal differences in follicular fluid but in serum cytokine concentrations, suggesting that the follicular immune system might not be significantly affected by gonadotropin stimulation.

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The clinical course of rhinovirus (RV)-associated wheezing illnesses is difficult to predict. We measured lactate dehydrogenase concentrations, RV load, antiviral and proinflammatory cytokines in nasal washes obtained from 126 preschool children with RV wheezy bronchitis. lactate dehydrogenase values were inversely associated with subsequent need for oxygen therapy. lactate dehydrogenase may be a useful biomarker predicting disease severity in RV wheezy bronchitis.

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PURPOSE To assess intra- and subretinal fluid during the loading phase with intravitreal ranibizumab in exudative age-related macular degeneration and to quantify the accuracy of crosshair scan spectral-domain optical coherence tomography with regard to retinal fluid. METHODS This is a retrospective study of 31 treatment-naive patients who received 3 monthly intravitreal ranibizumab injections. Visual acuity and the presence of retinal fluid were assessed at each visit using volume and crosshair scan protocols. RESULTS Visual acuity improved and central retinal thickness decreased significantly during the loading phase. However, retinal fluid persisted in two thirds of the patients. The accuracy of the crosshair scan to detect fluid was 93%. CONCLUSIONS A substantial proportion of eyes had persistent fluid after 3 months of ranibizumab injections. However, visual improvement was independent of residual fluid. Message: Crosshair scans detect relevant collections of retinal fluid accurately and may be sufficient in daily clinical practice. © 2015 S. Karger AG, Basel.

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Cystectomy and urinary diversion have high morbidity, and strategies to reduce complications are of utmost importance. Epidural analgesia and optimized fluid management are considered key factors contributing to successful enhanced recovery after surgery. In colorectal surgery, there is strong evidence that an intraoperative fluid management aiming for a postoperative zero fluid balance results in lower morbidity including a faster return of bowel function. Recently, a randomized clinical trial focusing on radical cystectomy demonstrated that a restrictive intraoperative hydration combined with a concomitant administration of norepinephrine reduced intraoperative blood loss, the need for blood transfusion and morbidity. The purpose of this review is to highlight specific anesthesiological aspects which have been shown to improve outcome after RC with urinary diversion.

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Our previous gene expression analysis identified phospholipase A2 group IIA (PLA2G2A) as a potential biomarker of ovarian endometriosis. The aim of this study was to evaluate PLA2G2A mRNA and protein levels in tissue samples (endometriomas and normal endometrium) and in serum and peritoneal fluid of ovarian endometriosis patients and control women. One-hundred and sixteen women were included in this study: the case group included 70 ovarian endometriosis patients, and the control group included 38 healthy women and 8 patients with benign ovarian cysts. We observed 41.6-fold greater PLA2G2A mRNA levels in endometrioma tissue, compared to normal endometrium tissue. Using Western blotting, PLA2G2A was detected in all samples of endometriomas, but not in normal endometrium, and immunohistochemistry showed PLA2G2A-specific staining in epithelial cells of endometrioma paraffin sections. However, there were no significant differences in PLA2G2A levels between cases and controls according to ELISA of peritoneal fluid (6.0 ± 4.4 ng/ml, 6.6 ± 4.3 ng/ml; p = 0.5240) and serum (2.9 ± 2.1 ng/ml, 3.1 ± 2.2 ng/ml; p = 0.7989). Our data indicate that PLA2G2A is implicated in the pathophysiology of ovarian endometriosis, but that it cannot be used as a diagnostic biomarker.

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A well developed theoretical framework is available in which paleofluid properties, such as chemical composition and density, can be reconstructed from fluid inclusions in minerals that have undergone no ductile deformation. The present study extends this framework to encompass fluid inclusions hosted by quartz that has undergone weak ductile deformation following fluid entrapment. Recent experiments have shown that such deformation causes inclusions to become dismembered into clusters of irregularly shaped relict inclusions surrounded by planar arrays of tiny, new-formed (neonate) inclusions. Comparison of the experimental samples with a naturally sheared quartz vein from Grimsel Pass, Aar Massif, Central Alps, Switzerland, reveals striking similarities. This strong concordance justifies applying the experimentally derived rules of fluid inclusion behaviour to nature. Thus, planar arrays of dismembered inclusions defining cleavage planes in quartz may be taken as diagnostic of small amounts of intracrystalline strain. Deformed inclusions preserve their pre-deformation concentration ratios of gases to electrolytes, but their H2O contents typically have changed. Morphologically intact inclusions, in contrast, preserve the pre-deformation composition and density of their originally trapped fluid. The orientation of the maximum principal compressive stress (σ1σ1) at the time of shear deformation can be derived from the pole to the cleavage plane within which the dismembered inclusions are aligned. Finally, the density of neonate inclusions is commensurate with the pressure value of σ1σ1 at the temperature and time of deformation. This last rule offers a means to estimate magnitudes of shear stresses from fluid inclusion studies. Application of this new paleopiezometer approach to the Grimsel vein yields a differential stress (σ1–σ3σ1–σ3) of ∼300 MPa∼300 MPa at View the MathML source390±30°C during late Miocene NNW–SSE orogenic shortening and regional uplift of the Aar Massif. This differential stress resulted in strain-hardening of the quartz at very low total strain (<5%<5%) while nearby shear zones were accommodating significant displacements. Further implementation of these experimentally derived rules should provide new insight into processes of fluid–rock interaction in the ductile regime within the Earth's crust.