JOURNAL OF FOOD SAFETY, Issue 2 2010
KARLA JOSEANE PEREZ
ABSTRACT The aim of this study was to investigate the influence of acid adaptation in the survival of Salmonella Enteritidis (SE86) and Salmonella Typhimurium (ST99) during exposure to simulated gastric fluid (SGF) and in intestinal infection of Rattus norvegicus. Acid-adapted and nonadapted Salmonella strains were exposed to SGF (pH 1.5) and were inoculated by gavage in adult rats. Results indicated that acid-adapted SE86 survived significantly better (P < 0.05) than nonadapted SE86, nonadapted ST99 and acid-adapted ST99 in SGF. Nonadapted microorganisms were observed in higher counts in feces than acid-adapted strains, while acid-adapted microorganisms demonstrated higher counts in intestine samples, suggesting intestinal invasion capacity. Acid-adapted SE86 was recovered in higher counts from ileum-cecum junction than the other microorganisms. PRACTICAL APPLICATIONS Salmonella Enteritidis has been identified as the most frequent serovar involved with the foodborne outbreaks in Brazil. In Southern Brazil, a specific strain of Salmonella Enteritidis (SE86) has been involved with more than 90% of the salmonellosis occurring in the last years, and the main food vehicle is home-made mayonnaise frequently added with different quantities of vinegar, which can cause acid adaptation in Salmonella cells. The results of this work indicate that SE86 presented higher acid adaptation, which contributed to higher survival rates in simulated gastric fluid and better intestinal colonization. These results could be related to human virulence and the frequent involvement of this strain with foodborne outbreaks in southern Brazil. [source]

SHORTNESS OF BREATH DURING DIALYSIS,A ROLE OF BICARBONATE IN DIALYSIS FLUID?

JOURNAL OF RENAL CARE, Issue 1 2008
Karen Latchford BSN
SUMMARY Occasionally dialysis patients show symptoms that indicate intolerance in the way dialysis is delivered. This paper describes two cases of transient shortness of breath during the initial treatments after starting online haemodiafiltration (HDF). Our actions to deal with these symptoms focused on reducing the bicarbonate gain during the first phase of the dialysis treatment. As the symptoms gradually disappeared we hypothesise that the bicarbonate concentration in the dialysis fluid may play an important role for the development of shortness of breath and hypoxemia during HDF treatments. [source]

Sertraline, a selective serotonin reuptake inhibitor, affects thirst, salt appetite and plasma levels of oxytocin and vasopressin in rats

EXPERIMENTAL PHYSIOLOGY, Issue 5 2007
Ana Paula De Magalhães-Nunes
We investigated the effects of chronic administration of sertraline (SERT; ,20 mg kg,1 day,1 in drinking water), a selective serotonin reuptake inhibitor, on water and sodium intake and on plasma levels of oxytocin (OT) and vasopressin (AVP) in basal and stimulated conditions. Basal water intake was reduced in SERT-treated rats. After 24 h of water deprivation, rats treated with SERT for 21 days ingested less water than the control rats (9.7 ± 0.5 versus 20.0 ± 0.9 ml, respectively, at 300 min after water presentation, P < 0.0001). Subcutaneous injection of 2 m NaCl or isoproterenol evoked a lower dipsogenic response in rats treated with SERT for 21 days. Fluid and food deprivation also induced a weaker dipsogenic response in SERT-treated rats (1.6 ± 0.5 versus 10.2 ± 1.2 ml, at 300 min, P < 0.0001) but had no effect on saline intake. Sodium depletion induced a higher natriorexigenic response in the SERT group (5.6 ± 1.3 versus 1.2 ± 0.3 ml, at 300 min, P < 0.0002). Higher urinary density and lower plasma sodium levels were observed after SERT treatment. Sertraline also increased plasma levels of vasopressin and oxytocin (AVP, 2.65 ± 0.36 versus 1.31 ± 0.16 pg ml,1, P < 0.005; OT, 17.16 ± 1.06 versus 11.3 ± 1.03 pg ml,1, P < 0.0009, at the third week post-treatment). These data constitute the first evidence that chronic SERT treatment affects water and sodium intake in rats. These effects seem to be related to the hyponatraemia caused by the higher plasma levels of AVP and OT. [source]

Syntectonic infiltration by meteoric waters along the Sevier thrust front, southwest Montana

GEOFLUIDS (ELECTRONIC), Issue 4 2006
A. C. RYGEL
Abstract Structural, petrographic, and isotopic data for calcite veins and carbonate host-rocks from the Sevier thrust front of SW Montana record syntectonic infiltration by H2O-rich fluids with meteoric oxygen isotope compositions. Multiple generations of calcite veins record protracted fluid flow associated with regional Cretaceous contraction and subsequent Eocene extension. Vein mineralization occurred during single and multiple mineralization events, at times under elevated fluid pressures. Low salinity (Tm = ,0.6°C to +3.6°C, as NaCl equivalent salinities) and low temperature (estimated 50,80°C for Cretaceous veins, 60,80°C for Eocene veins) fluids interacted with wall-rock carbonates at shallow depths (3,4 km in the Cretaceous, 2,3 km in the Eocene) during deformation. Shear and extensional veins of all ages show significant intra- and inter-vein variation in ,18O and ,13C. Carbonate host-rocks have a mean ,18OV-SMOW value of +22.2 ± 3, (1,), and both the Cretaceous veins and Eocene veins have ,18O ranging from values similar to those of the host-rocks to as low as +5 to +6,. The variation in vein ,13CV-PDB of ,1 to approximately +6, is attributed to original stratigraphic variation and C isotope exchange with hydrocarbons. Using the estimated temperature ranges for vein formation, fluid (as H2O) ,18O calculated from Cretaceous vein compositions for the Tendoy and Four Eyes Canyon thrust sheets are ,18.5 to ,12.5,. For the Eocene veins within the Four Eyes Canyon thrust sheet, calculated H2O ,18O values are ,16.3 to ,13.5,. Fluid,rock exchange was localized along fractures and was likely coincident with hydrocarbon migration. Paleotemperature determinations and stable isotope data for veins are consistent with the infiltration of the foreland thrust sheets by meteoric waters, throughout both Sevier orogenesis and subsequent orogenic collapse. The cessation of the Sevier orogeny was coincident with an evolving paleogeographic landscape associated with the retreat of the Western Interior Seaway and the emergence of the thrust front and foreland basin. Meteoric waters penetrated the foreland carbonate thrust sheets of the Sevier orogeny utilizing an evolving mesoscopic fracture network, which was kinematically related to regional thrust structures. The uncertainty in the temperature estimates for the Cretaceous and Eocene vein formation prevents a more detailed assessment of the temporal evolution in meteoric water ,18O related to changing paleogeography. Meteoric water-influenced ,18O values calculated here for Cretaceous to Eocene vein-forming fluids are similar to those previously proposed for surface waters in the Eocene, and those observed for modern-day precipitation, in this part of the Idaho-Montana thrust belt. [source]

Special Issue: Fluid,structure interaction in biomedical applications

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 3-4 2010
R. van Loon Guest Editor
Abstract The aim of this issue was to bring together computational studies in a variety of research areas, where biological fluids interact with tissue. This resulted in a selection of papers on blood/vessel, blood/valve, air/lung and cell/platelet/blood interaction. Although convergence, robustness and accuracy of the methods involved clearly play an important role in fluid,structure interaction modelling, particular attention is given to the applications. Copyright © 2010 John Wiley & Sons, Ltd. [source]

FOIST: Fluid,object interaction subcomputation technique

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 9 2009
V. Udoewa
Abstract Our target is to develop computational techniques for studying aerodynamic interactions between multiple objects. The computational challenge is to predict the dynamic behavior and path of the object, so that separation (the process of objects relatively falling or moving away from each other) is safe and effective. This is a very complex problem because it has an unsteady, 3D nature and requires the solution of complex equations that govern the fluid dynamics (FD) of the object and the aircraft together, with their relative positions changing in time. Large-scale 3D FD simulations require a high computational cost. Not only must one solve the time-dependent Navier,Stokes equations governing the fluid flow, but also one must handle the equations of motion of the object as well as the treatment of the moving domain usually treated as a type of pseudo-solid. These costs include mesh update methods, distortion-limiting techniques, and remeshing and projection tactics. To save computational costs, point force calculations have been performed in the past. This paper presents a hybrid between full mesh-moving simulations and the point force calculation. This mesh-moving alternative is called FOIST: fluid,object subcomputation interaction technique. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Fluid,structure interaction problems with strong added-mass effect

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 10 2009
S. R. Idelsohn
Abstract In this paper, the so-called added-mass effect is investigated from a different point of view of previous publications. The monolithic fluid,structure problem is partitioned using a static condensation of the velocity terms. Following this procedure the classical stabilized projection method for incompressible fluid flows is introduced. The procedure allows obtaining a new pressure segregated scheme for fluid,structure interaction problems, which has good convergent characteristics even for biomechanical application, where the added-mass effect is strong. The procedure reveals its power when it is shown that the same projection technique must be implemented in staggered FSI methods. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Fixed-grid fluid,structure interaction in two dimensions based on a partitioned Lattice Boltzmann and p -FEM approach

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 7 2009
S. Kollmannsberger
Abstract Over the last decade the Lattice Boltzmann method, which was derived from the kinetic gas theory, has matured as an efficient approach for solving Navier,Stokes equations. The p -FEM approach has proved to be highly efficient for a variety of problems in the field of structural mechanics. Our goal is to investigate the validity and efficiency of coupling the two approaches to simulate transient bidirectional Fluid,Structure interaction problems with geometrically non-linear structural deflections. A benchmark configuration of self-induced large oscillations for a flag attached to a cylinder can be accurately and efficiently reproduced within this setting. We describe in detail the force evaluation techniques, displacement transfers and the algorithm used to couple these completely different solvers as well as the results, and compare them with a benchmark reference solution computed by a monolithic finite element approach. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Fluid,solid interaction problems with thermal convection using the immersed element-free Galerkin method

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 1 2010
Claudio M. Pita
Abstract In this work, the immersed element-free Galerkin method (IEFGM) is proposed for the solution of fluid,structure interaction (FSI) problems. In this technique, the FSI is represented as a volumetric force in the momentum equations. In IEFGM, a Lagrangian solid domain moves on top of an Eulerian fluid domain that spans over the entire computational region. The fluid domain is modeled using the finite element method and the solid domain is modeled using the element-free Galerkin method. The continuity between the solid and fluid domains is satisfied by means of a local approximation, in the vicinity of the solid domain, of the velocity field and the FSI force. Such an approximation is achieved using the moving least-squares technique. The method was applied to simulate the motion of a deformable disk moving in a viscous fluid due to the action of the gravitational force and the thermal convection of the fluid. An analysis of the main factors affecting the shape and trajectory of the solid body is presented. The method shows a distinct advantage for simulating FSI problems with highly deformable solids. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Acoustic upwinding for sub- and super-sonic turbulent channel flow at low Reynolds number

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2007
H. C. de LangeArticle first published online: 13 FEB 200
Abstract A recently developed asymmetric implicit fifth-order scheme with acoustic upwinding for the spatial discretization for the characteristic waves is applied to the fully compressible, viscous and non-stationary Navier,Stokes equations for sub- and super-sonic, mildly turbulent, channel flow (Re,=360). For a Mach number of 0.1, results are presented for uniform (323, 643 and 1283) and non-uniform (expanding wall-normal, 323 and 643) grids and compared to the (incompressible) reference solution found in (J. Fluid. Mech. 1987; 177:133,166). The results for uniform grids on 1283 and 643 nodes show high resemblance with the reference solution. Expanding grids are applied on 643 - and 323 -node grids. The capability of the proposed technique to solve compressible flow is first demonstrated by increasing the Mach number to 0.3, 0.6 and 0.9 for isentropic flow on the uniform 643 -grid. Next, the flow speed is increased to Ma=2. The results for the isothermal-wall supersonic flows give very good agreement with known literature results. The velocity field, the temperature and their fluctuations are well resolved. This means that in all presented (sub- and super-sonic) cases, the combination of acoustic upwinding and the asymmetric high-order scheme provides sufficient high wave-number damping and low wave-number accuracy to give numerically stable and accurate results. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Comparative study of the continuous phase flow in a cyclone separator using different turbulence models,

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2005
H. Shalaby
Abstract Numerical calculations were carried out at the apex cone and various axial positions of a gas cyclone separator for industrial applications. Two different NS-solvers (a commercial one (CFX 4.4 ANSYS GmbH, Munich, Germany, CFX Solver Documentation, 1998), and a research code (Post-doctoral Thesis, Technical University of Chemnitz, Germany, September, 2002)) based on a pressure correction algorithm of the SIMPLE method have been applied to predict the flow behaviour. The flow was assumed as unsteady, incompressible and isothermal. A k,, turbulence model has been applied first using the commercial code to investigate the gas flow. Due to the nature of cyclone flows, which exhibit highly curved streamlines and anisotropic turbulence, advanced turbulence models such as Reynolds stress model (RSM) and large eddy simulation (LES) have been used as well. The RSM simulation was performed using the commercial package activating the Launder et al.'s (J. Fluid. Mech. 1975; 68(3):537,566) approach, while for the LES calculations the research code has been applied utilizing the Smagorinsky model. It was found that the k,, model cannot predict flow phenomena inside the cyclone properly due to the strong curvature of the streamlines. The RSM results are comparable with LES results in the area of the apex cone plane. However, the application of the LES reveals qualitative agreement with the experimental data, but requires higher computer capacity and longer running times than RSM. This paper is organized into five sections. The first section consists of an introduction and a summary of previous work. Section 2 deals with turbulence modelling including the governing equations and the three turbulence models used. In Section 3, computational parameters are discussed such as computational grids, boundary conditions and the solution algorithm with respect to the use of MISTRAL/PartFlow-3D. In Section 4, prediction profiles of the gas flow at axial and apex cone positions are presented and discussed. Section 5 summarizes and concludes the paper. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Computational predictability of time-dependent natural convection flows in enclosures (including a benchmark solution)

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 8 2002
Mark A. Christon
Abstract This paper summarizes the results from a special session dedicated to understanding the fluid dynamics of the 8:1 thermally driven cavity which was held at the First MIT Conference on Computational Fluid and Solid Dynamics in June, 2001. The primary objectives for the special session were to: (1) determine the most accurate estimate of the critical Rayleigh number above which the flow is unsteady, (2) identify the correct, i.e. best time-dependent benchmark solution for the 8: 1 differentially heated cavity at particular values of the Rayleigh and Prandtl numbers, and (3) identify those methods that can reliably provide these results. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Supercritical Fluid,Liquid,Solid (SFLS) Synthesis of Si and Ge Nanowires Seeded by Colloidal Metal Nanocrystals,

ADVANCED MATERIALS, Issue 5 2003
T. Hanrath
Abstract Semiconductor nanowires, 5 to 20 nm in diameter and micrometers in length, appear to be promising candidates for a variety of new technologies, including computing, memory, and sensor applications. Suitable for these applications, silicon (Si) and germanium (Ge) nanowires ranging from 4 to 30 nm in diameter and micrometers in length can be produced in high temperature supercritical fluids by thermally degrading organosilane or organogermane precursors in the presence of organic-monolayer-protected gold nanocrystals. Although gas phase vapor,liquid,solid (VLS) methods can be used to produce a variety of different nanowire materials, high temperature supercritical fluids provide wire size control through nanocrystal size selection prior to synthesis, and high product yields due to the high precursor solubility. [source]

Fluid Flow Induction of Cyclo-Oxygenase 2 Gene Expression in Osteoblasts Is Dependent on an Extracellular Signal-Regulated Kinase Signaling Pathway,,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2002
Sunil Wadhwa
Abstract Mechanical loading of bone may be transmitted to osteocytes and osteoblasts via shear stresses at cell surfaces generated by the flow of interstitial fluid. The stimulated production of prostaglandins, which mediates some effects of mechanical loading on bone, is dependent on inducible cyclo-oxygenase 2 (COX-2) in bone cells. We examined the fluid shear stress (FSS) induction of COX-2 gene expression in immortalized MC3T3-E1 osteoblastic cells stably transfected with ,371/+70 base pairs (bp) of the COX-2 5,-flanking DNA (Pluc371) and in primary osteoblasts (POBs) from calvaria of mice transgenic for Pluc371. Cells were plated on collagen-coated glass slides and subjected to steady laminar FSS in a parallel plate flow chamber. FSS, from 0.14 to10 dynes/cm2, induced COX-2 messenger RNA (mRNA) and protein. FSS (10 dynes/cm2) induced COX-2 mRNA within 30 minutes, with peak effects at 4 h in MC3T3-E1 cells and at ,8 h in POBs. An inhibitor of new protein synthesis puromycin blocked the peak induction of COX-2 mRNA by FSS. COX-2 promoter activity, measured as luciferase activity, correlated with COX-2 mRNA expression in both MC3T3-E1 and POB cells. FSS induced phosphorylation of extracellular signal-regulated kinase (ERK) in MC3T3-E1 cells, with peak effects at 5 minutes. Inhibiting ERK phosphorylation with the specific inhibitor PD98059 inhibited FSS induction of COX-2 mRNA by 55-70% and FSS stimulation of luciferase activity by ,80% in both MC3T3-E1 and POB cells. We conclude that FSS transcriptionally induces COX-2 gene expression in osteoblasts, that the maximum induction requires new protein synthesis, and that induction occurs largely via an ERK signaling pathway. [source]

Extraction and Removal of Caffeine from Green Tea by Ultrasonic-Enhanced Supercritical Fluid

JOURNAL OF FOOD SCIENCE, Issue 4 2010
Wei-Qiang Tang
ABSTRACT:, Low-caffeine or caffeine-removed tea and its products are widely welcomed on market in recent years. In the present study, we adopt ultrasonic-enhanced supercritical fluid extraction process to remove caffeine from green tea. An orthogonal experiment (L16 (45)) was applied to optimize the best removal conditions. Extraction pressure, extraction time, power of ultrasound, moisture content, and temperature were the main factors to influence the removal rate of caffeine from green tea. The 5 factors chosen for the present investigation were based on the results of a single-factor test. The optimum removal conditions were determined as follows: extraction pressure of 30 MPa, temperature at 55 °C, time of 4 h, 30% moisture content, and ultrasound power of 100 W. Chromatogram and ultraviolet analysis of raw material and decaffeinates suggests that under optimized conditions, the caffeine of green tea was effectively removed and minished without damaging the structure of active ingredients in green tea. [source]

Hydrodynamic Cavitation to Improve Bulk Fluid to Surface Mass Transfer in a Nonimmersed Ultraviolet System for Minimal Processing of Opaque and Transparent Fluid Foods

JOURNAL OF FOOD SCIENCE, Issue 9 2007
P.J. Milly
ABSTRACT:, Ultraviolet (UV)-induced chemical reactions and inactivation of microorganisms in transparent and opaque fluids are strongly dependent upon the homogenous exposure of the target species to the UV irradiation. Current UV technologies used in water disinfection and food preservation applications have limited efficacy due to suspended particles shading target species. An Ultraviolet-Shockwave PowerÔ Reactor (UV-SPR) consisting of an inner rotating rotor and a stationary quartz housing and 2 end plates was used to induce ,controlled cavitation.' Eight UV low-pressure mercury lamps spaced uniformly were installed lengthwise around the quartz housing periphery. A KI to I3,chemical dosimeter for UV was used to quantify photons received by fluid in the annular space of the SPR. UV dose (J/m2) increased from 97 J/m2 at 0 rpm to over 700 J/m2 for SPR speeds above 2400 rpm. Inactivation of E. coli 25922 in apple juice and skim milk in the UV-SPR at exit temperatures below 45 °C was greater than 4.5 and 3 logs, respectively. The UV-SPR system proved successful in increasing the mass transfer of transparent and opaque fluid to the UV irradiated surface. [source]

Vitreous Fluid and/or Urine Glucose Concentrations in 1335 Civil Aviation Accident Pilot Fatalities,

JOURNAL OF FORENSIC SCIENCES, Issue 3 2009
Arvind K. Chaturvedi Ph.D.
Abstract:, During aviation accident investigations, vitreous fluid and urine samples from pilot fatalities are analyzed for glucose and blood for hemoglobin A1c (HbA1c) to monitor diabetic pilots and to discover other pilots with undiagnosed/unreported diabetes. The prevalence of elevated glucose concentrations in fatally injured pilots was evaluated by searching the Civil Aerospace Medical Institute's Toxicology Database for the period 1998,2005. Out of 1335 pilots involving 363 vitreous fluid, 365 urine, and 607 vitreous fluid and urine analyses, 43 pilots had elevated glucose in vitreous fluid (>125 mg/dL) and/or in urine (>100 mg/dL). Of the 20 pilots whose blood samples were analyzed, nine had >6% HbA1c,four were known diabetics, and five were unknown diabetics. Urinary glucose levels were elevated in all 13 known hyperglycemic pilots. A considerable number of pilots (30 of 43) had elevated glucose and HbA1c (5 of 20), suggesting undiagnosed/unreported diabetic conditions. [source]

One-hour fast for water and six-hour fast for solids prior to endoscopy provides good endoscopic vision and results in minimum patient discomfort

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 6 2009
Arjuna P De Silva
Abstract Background and Aim:, Current guidelines for upper gastrointestinal endoscopy (UGIE) advise at least 6,8 h fasting for solids and 4-h fasting for liquids. We aimed to determine whether a 6-h fast for solids and one-hour fast for water prior to UGIE gives good endoscopic vision and less patient discomfort. Methods:, 128 patients referred for UGIE were given a standard meal 6 h before endoscopy, and then randomized to either nil by mouth for 6 h (group A, n = 65) or allowed to drink water for up to one hour prior to endoscopy (group B, n = 63). Before endoscopy patients were requested to indicate discomfort due to fasting on a visual analog scale. Fluid in the gastric fundus was aspirated, when present, for volume and pH measurements, and endoscopic vision was graded. Results:, 53 patients in group A and 43 patients in group B completed the study. Discomfort was significantly lower in group B than group A (P < 0.0001). Endoscopic vision was good in all 53 patients in group A and 40 in group B, and average in 3 patients in group B. Fluid in the gastric fundus was noted in 11 patients in group A and 16 in group B, but there were no significant differences in volume or pH between groups. There were no complications attributable to endoscopy in either group. Conclusions:, A 6-h fast for solids and a 1-h fast for water prior to UGIE gives good endoscopic vision, and causes minimum patient discomfort. [source]

Fluid and electrolyte management

JOURNAL OF HOSPITAL MEDICINE, Issue S2 2010
Article first published online: 8 APR 2010
No abstract is available for this article. [source]

Solvent-mediated solid phase transformations of carbamazepine: Effects of simulated intestinal fluid and fasted state simulated intestinal fluid

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2009
Paula Lehto
Abstract Solvent-mediated transformations of carbamazepine (CBZ) anhydrate form III were investigated in Simulated Intestinal Fluid, a simple USP buffer medium, and in FaSSIF, which contains sodium taurocholate (STC) and lecithin, important surfactants that solubilize lipophilic drugs and lipids in the gastrointestinal tract. Raman spectroscopy (in situ) was utilized to reveal the connection between the changes in solid phase composition and dissolution rate while simultaneously detecting the solid state and the dissolved amount of CBZ. Initial dissolution rate was clearly higher in FaSSIF, while the solid phase data revealed that the crystallization of CBZ dihydrate was inhibited in both the dissolution media, albeit by different mechanisms. In SIF this inhibition was related to extensive needle growth, which impeded medium contact with the solid surface by forming a sterical barrier leading to retarded crystallization rates. Morphological changes from the needle-like dihydrate crystals to plate-like counterparts in FaSSIF, combined with the information that the transformation process was leveled off, evidenced strong hydrogen bonding behavior between the CBZ and STC molecules. These results underline the importance of biologically representative dissolution media in linking the in vitro dissolution results of solids that are capable of hydrate formation to their in vivo dissolution behavior. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:985,996, 2009 [source]

Hydrolysis of ,-Tricalcium Phosphate in Simulated Body Fluid and Dehydration Behavior During the Drying Process

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2007
Xiang Wei
The hydrolysis of ,-tricalcium phosphate (,-TCP) in a simulated body fluid (SBF) at 37°C was investigated. The hydration rate was found to be slower in SBF than that in deionized water. The concentration of ions in SBF was monitored by ICP. The hydrolysis product, which was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infra red, and X-ray photoelectron spectroscopy, was determined to be carbonate-containing, calcium-deficient hydroxyapatite (CO3,CDHAp) with Mg2+, Na+, and Cl, impurities similar to the biological apatite. An amorphous layer on the ,-TCP surface was found to be the precursor of the apatite phase, which may either form crystalline apatite or may decompose back to ,-TCP at a lower temperature. [source]

Evaluation of Abdominal Fluid: Peripheral Blood Creatinine and Potassium Ratios for Diagnosis of Uroperitoneum in Dogs

JOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 4 2001
Chad Schmiedt DVM, DACVS
Objective:To determine the clinical efficacy of abdominal fluid to peripheral blood ratios of creatinine and potassium concentrations to diagnose uroperitoneum in dogs. Design:Records of 13 dogs with confirmed uroabdomen were retrospectively analyzed. Prospective evaluation of 8 dogs with nonrenal ascites provided data for a control population. Setting:Veterinary Medical Teaching Hospital. Animals:Client owned dogs. Interventions:None Measurements and Main Results:Abdominal fluid potassium (mEq/L) and creatinine concentrations (mg/dl) were recorded. Peripheral blood potassium and creatinine concentrations were also recorded. Ratios were calculated based on these values. An abdominal fluid creatinine concentration to peripheral blood creatinine concentration ratio of > 2:1 was predictive of uroabdomen in dogs (specificity 100%, sensitivity 86%). An abdominal fluid potassium concentration to peripheral blood potassium concentration of > 1.4:1 is also predictive of uroabdomen in dogs (specificity 100%, sensitivity 100%). All dogs with uroabdomen had an abdominal fluid creatinine concentration that was at least 4 times normal peripheral blood levels. Conclusion:Abdominal fluid to peripheral blood potassium and creatinine ratios provide a means to diagnose uroperitoneum in dogs without elevated peripheral blood creatinine. [source]

Comparison of Four Staining Methods for Detection of Mast Cells in Equine Bronchoalveolar Lavage Fluid

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 2 2006
Mathilde Leclere
Mast cells normally are present in equine bronchoalveolar lavage fluid (BALF), but usually represent <2% of all cells in healthy horses. An increased percentage of mast cells has been associated with airway hyperactivity and inflammatory airway diseases, but marked differences are reported between studies in normal and diseased horses. Because an abnormal mast cell count may be of clinical relevance, we compared the ability of a fast Romanowsky method to stain mast cell granules with that of 3 metachromatic stains: automated Romanowsky, May-Grünwald Giemsa, and toluidine blue stains. The BALF cells from 24 horses were studied. A differential cell count was performed blindly on 400 cells. The percentages of mast cells obtained were analyzed by means of repeated-measures analysis of variance and Fischer's PLSD test. The Bland and Altman method was used to assess agreement among stains. The mean percentage of mast cells in BALF was significantly lower with the fast Romanowsky than with the automated Romanowsky, May-Grünwald Giemsa, and toluidine blue stains. With the fast Romanowsky stain, the metachromatic granules of mast cells were not stained, and their identification was based on morphologic criteria. Toluidine blue staining allowed detection of the highest mean percentage of mast cells, but was inadequate for performing a differential cell count on other cell types. In conclusion, fast Romanosky stain may be inadequate for detection of mast cells in equine BALF, whereas automated Romanowsky, May-Grünwald Giemsa, and toluidine blue stains provide metachromatic staining of mast cell granules. [source]

Biochemical Analysis of Pericardial Fluid and Whole Blood in Dogs with Pericardial Effusion

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 6 2005
Armelle M. de Laforcade
Studies evaluating pericardial fluid analysis in dogs to determine the etiology of pericardial effusions have yielded conflicting results. The purpose of this prospective study was to compare acid-base status, electrolyte concentrations, glucose, and lactate of pericardial fluid to peripheral blood from dogs with pericardial effusion and to compare these variables between dogs with neoplastic and nonneoplastic pericardial effusion. Acid-base status, electrolyte concentrations, glucose, hematocrit, urea nitrogen, and lactate concentrations were evaluated in peripheral blood samples and in pericardial effusion samples of 41 client-owned dogs with pericardial effusion. Common abnormal findings in the peripheral blood of dogs with pericardial effusion included hyperlactatemia (n = 38 [of 41]; 93%), hyponatremia (n = 25/41; 61%), hyperglycemia (n = 13/41; 32%), and hypermagnesemia (n = 13/41; 32%). Bicarbonate, sodium, ionized calcium, glucose, and hematocrit were all significantly lower in the pericardial fluid compared with peripheral blood, whereas lactate, chloride, and PCO2 were significantly higher in the pericardial fluid. When comparing the concentrations of variables in the pericardial fluid of dogs with neoplasia (n = 28) to those without neoplasia (n = 13), pH, bicarbonate, and chloride were significantly lower in dogs with neoplasia, whereas lactate, hematocrit, and urea nitrogen were significantly higher in the pericardial fluid of dogs with neoplasia. The difference between peripheral and pericardial glucose concentrations was significantly larger in dogs with neoplasia than in dogs without neoplasia. Although differences between variables in dogs with neoplastic and nonneoplastic pericardial effusion were documented, clinical relevance is likely limited by the degree of overlap between the 2 groups. [source]

Effect of Age and Abomasal Puncture on Peritoneal Fluid, Hematology, and Serum Biochemical Analyses in Young Calves

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 6 2005
Luiz Claudio N. Mendes
The goals of this study were to evaluate techniques for collection of peritoneal fluid from calves, establish reference ranges for fibrinogen in peritoneal fluid during the 1st month of life, and determine if abomasal puncture would alter peritoneal fluid or hematologic variables. Twenty-two healthy Holstein calves underwent 3 peritoneal fluid collections on day 1, day 15, and day 30 of age. Fibrinogen concentration in peritoneal fluid was 0.20 g/dL and 0.10 g/dL (P < .05) for day 1 and day 30, respectively, and 0.10 at day 15 (P > .05) for calves without abomasal puncture. Plasma fibrinogen concentration was 0.60 g/dL and 0.70 g/dL (P < .05) for days 15 and 30, respectively, in calves without abomasal puncture. There were no significant differences (P, .05) in peritoneal fluid and peripheral blood total protein and fibrinogen concentrations, specific gravity, total and differential cell count, or erythrocyte counts between calves with or without abomasal puncture. We concluded that the reference ranges established for fibrinogen and total protein concentration are important for accurate evaluation of peritoneal fluid in calves for further comparison with similar-aged animals with gastrointestinal-tract or abdominal-cavity disease. Additionally, accidental abomasal puncture does not alter values of fibrinogen, total protein, and nucleated cell count in peritoneal fluid and does not cause apparent clinical abnormalities. [source]

Transient Osmotic Absorption of Fluid in Microvessels Exposed to Low Concentrations of Dimethyl Sulfoxide

MICROCIRCULATION, Issue 1 2006
CATHERINE A. GLASS
ABSTRACT Dimethyl Sulfoxide (DMSO) is a common solvent for pharmacological agents. It is a small, lipophilic molecule thought to be relatively highly permeable through the cell membrane. While measuring the effect of low concentrations of DMSO (0.05,0.5% v/v) on capillary hydraulic conductivity as a vehicle control for pharmacological agents, the authors noticed what appeared to be an unusual transient absorption of fluid across the vessel wall. This absorption occurred during occlusion of the vessel, but dissipated quickly (1.7,8.6 s). The transient reabsorption reappeared upon each successive occlusion. To determine the nature of this transient absorption, the authors have measured the effect of increasing the pressure of the perfusing solution, of the concentration and time of perfusion of DMSO, and of superfusing the DMSO. They found that the absorption rate, but not the filtration rate, was concentration dependent, and was significantly correlated with the osmotic pressure of the DMSO. Moreover, the time taken for completion of the transient, i.e., time to reversal of flow, was inversely proportional to the hydraulic conductivity of the vessel. Furthermore, the transient absorption could be reduced and eventually abolished by increasing the hydrostatic pressure. These results strongly suggested that perfusion with low concentrations of DMSO could set up a significant osmotic pressure gradient across the vessel wall. This proposed mechanism for the absorption was confirmed by the measurement of a significant osmotic reflection coefficient of the vessel wall to DMSO (0.11 ± 0.01). Relatively low concentrations (0.05,0.5%) of DMSO were therefore able to stimulate a significant osmotic transient across the blood vessel walls. [source]

Relationship of Ultrafiltration and Anastomotic Flow in Isolated Rat Lungs

MICROCIRCULATION, Issue 5 2001
WEN LIN
ABSTRACT Objective: When arterial and venous pressures are increased to equal values in "stop-flow" studies, perfusate continues to enter the pulmonary vasculature from the arterial and venous reservoirs. Losses of fluid from the pulmonary vasculature are due to ultrafiltration and flow through disrupted anastomotic (bronchial) vessels. This study compared the relative sites of ultrafiltration and anastomotic flows at low and high intravascular pressures. Methods: Isolated rat lungs were perfused for 10 minutes with FITC-dextran, which was used to detect ultrafiltration. Arterial and venous catheters were then connected to reservoirs containing radioactively labeled dextrans at 20 or 30 cm H2O for 10 minutes. The vasculature was subsequently flushed into serial vials, and ultrafiltration and vascular filling during the equal-pressure interval were calculated. Results: Ultrafiltration equaled 0.43 ± 0.11 mL at 20 cm H2O and was similar to the volume of fresh arterial and venous perfusate which entered and remained in the pulmonary vasculature during the equal-pressure interval (0.45 ± 0.10 mL). At 30 cm H2O, 0.80 ± 0.23 mL entered and remained in the vasculature during the equal-pressure interval, replacing the original perfusate, and calculated transudation (0.56 ± 0.09 mL) was not significantly more than at 20 cm H2O. Fluid also entered the airspaces at 30 cm H2O but not at 20 cm H2O. Conclusions: At 20 cm H2O, flow through anastomotic vessels occurs at sites that are at the arterial and venous ends of the microcirculation. Flow in exchange vessels remains minimal, permitting measurements of ultrafiltration and exchange. Losses of perfusate from the pulmonary vessels complicate measurements of ultrafiltration at 30 cm H2O. [source]

Cytologie Du Liquide Cephaloricachidien (Cytology of the Cerebrospinal Fluid)

NEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 4 2005
Roy O. Weller
No abstract is available for this article. [source]

Maxwell Fluid Model for Generation of Stress,Strain Curves of Viscoelastic Solid Rocket Propellants

PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 4 2010
Himanshu Shekhar
Abstract Solid rocket propellants are modeled as Maxwell Fluid with single spring and single dashpot in series. Complete stress,strain curve is generated for case-bonded composite propellant formulations by taking suitable values of spring constant and damping coefficient. Propellants from same lot are tested at different strain rate. It is observed that change in spring constant, representing elastic part is very small with strain rate but damping constant varies significantly with variation in strain rate. For a typical propellant formulation, when strain rate is varied from 0.00037 to 0.185 per second, spring constant (K) changed from 5.5 to 7.9,MPa, but damping coefficient (D) varied from 1400 to 4,MPas. For all strain rates, stress,strain curve is generated using developed Maxwell model and close matching with actual test curve is observed. This indicates validity of Maxwell fluid model for case-bonded solid propellant formulations. It is observed that with increases in strain rate, spring constant increases but damping coefficient decreases representing solid rocket propellant as a true viscoelastic material. It is also established that at higher strain rate, damping coefficient becomes negligible as compared to spring constant. It is also observed that variation of spring constant is logarithmic with strain rate and that of damping coefficient follows a power law. The correlation coefficients are introduced to ascertain spring constants and damping coefficients at any strain rate from that at a reference strain rate. Correlation for spring constant needs a coefficient "H," which is function of propellant formulation alone and not of test conditions and the equation developed is K2=(K1 - H)×{ln(d,2/dt)/ln(d,1/dt)}+H. Similarly for damping coefficient (D) also another constant "S" is introduced and prediction formula is given by D2=D1×{(d,2/dt)/(d,1/dt)}S. Evaluating constants "H" and "S" at different strain rates validate this mathematical formulation for different propellant formulations. Close matching of test and predicted stress,strain curve indicates propellant behavior as viscoelastic Maxwell Fluid. Uniqueness of approach is to predict complete stress,strain curves, which are not attempted by any other researchers. [source]