Matched Fluid Research Articles

3D Lagrangian Particle Tracking In A Model Of The Human Airways

The three-dimensional flow field in the trachea of a physiologically correct model of the human respiratory tract from the nasal/oral cavities up to the 6th bronchi generation is investigated. The investigations comprise steady inflow conditions, i.e., steady inhalation and oscillatory flow combining inspiration and expiration to simulate calm breathing. A realistic breathing pattern is approximated by a sinusoidal waveform for two Womersley numbers of 3 and 4.5 and two Reynolds numbers of 400 and 1200. Due to the inherent three-dimensional and asymmetric nature of the flow field, 3D particle-tracking velocimetry (3D-PTV) measurements are performed using the Shake-The-Box (StB) algorithm to determine the influence of oral and nasal inhalation and exhalation on the flow field in the lower human airways. By using a refractive-index matched fluid consisting of water and glycerin, the complex flow structures inside the trachea are fully resolved. During oscillatory inhalation/exhalation, an integration window size of 6/40 pi was chosen as it can be considered short enough to assume a steady state. The PTV measurements confirm that the nasal and/or oral cavity must be taken into account when analyzing the flow field in the lower respiratory tract. Characteristic sets of velocity profiles in the sagittal and coronal plane of the trachea as well as contour plots evidence nearly identical flow structures for both oral and nasal inhalation, but also reveal that the presence of both cavities possesses a huge impact on the flow field compared to ideal, i.e., fully developed inflow conditions

Next-generation sequencing of pancreatic cyst wall specimens obtained using micro-forceps for improving diagnostic accuracy.

Background and study aims Pancreatic cysts are common incidental findings, with an estimated prevalence of 13% to 15% in imaging done for other reasons. Diagnosis often relies on collection of cyst fluid, but tissue sampling using micro-forceps may allow for a more reliable diagnosis and higher yield of DNA for next-generation sequencing (NGS). The primary aim was to assess the performance of NGS in identifying mucinous cyst. The secondary aims were to assess DNA yield between the cyst fluid and cyst wall tissue, complication rate and performance of conventional investigations. Patients and methods Twenty-four patients referred for endoscopic ultrasound were recruited. Biopsies were taken using micro-forceps and the AmpliSeq Cancer Hotspot panel was used for NGS, a polymerase chain reaction assay targeting several hotspots within 50 genes, including GNAS , KRAS and VHL . Results The concentration of DNA extracted from 24 cyst wall samples was significantly higher than in the nine of 24 available matched cyst fluid samples. The sensitivity, specificity, and diagnostic accuracy of NGS for diagnosing mucinous cyst were 93%, 50% and 84%; for standard of care, they were -66.6%, 50% and 63.1%; and for standard of care with NGS, they were 100%, 50%, and 89.4% respectively. Cyst wall biopsy was able to diagnose 19 of 24 cysts (4 high risk, 7 intraductal papillary mucinous neoplasms, 4 cysts of mucinous origin, and 4 benign). Conclusions NGS data correlate well with histology and may aid in diagnosis and risk stratification of pancreatic cysts. Cyst wall biopsy performs well in diagnosing cysts but was inadequate in five of 24 patients.

Sex-Differences and Associations Between Complement Activation and Synovial Vascularization in Patients with Late-Stage Knee Osteoarthritis.

PurposeSynovial inflammation in knee osteoarthritis (OA) causes disorganized synovial angiogenesis and complement activation in synovial fluid, but links between complement and synovial microvascular pathology have not been established. Since complement causes vascular pathology in other diseases and since sex-differences exist in complement activation and in OA, we investigated sex differences in synovial fluid complement factors, synovial tissue vascular pathology, and associations between complement and synovial vascular pathology in patients with late-stage knee OA.MethodsPatients with symptomatic, late-stage radiographic knee OA undergoing total knee arthroplasty or high tibial osteotomy provided matched synovial fluid and tissue biopsies during surgery. Complement factors (C2, C5, adipsin, MBL, and CFI) and terminal complement complex (sC5b-C9) were measured in synovial fluid by multiplex or enzyme-linked immunosorbent assay, respectively. Features of synovial vascular pathology (vascularization, perivascular edema, and vasculopathy) were assessed by histopathology. Multivariate linear regression models were used to assess associations between synovial fluid complement factors and histopathological features of vascular pathology, with adjustment for age, sex, body mass index, and sex interaction. Sex-disaggregated comparisons were completed.ResultsSynovial fluid biomarker and histopathology data were included from 97 patients. Most synovial fluid complement factors and synovial tissue histopathological features were similar between sexes. Synovial fluid C5 trended to lower levels in males (-20.93 ng/mL [95%CI -42.08, 0.23] p=0.05). Median vasculopathy scores (0.42 [95%CI 0.07, 0.77] p=0.02) were higher in males. In the full cohort, C5 concentration was associated with lower vascularization scores (-0.005 [95%CI -0.010, -0.0001] p=0.04) while accounting for sex*C5 interaction. In sex-disaggregated analyses, increased C5 concentration was associated with lower vascularization scores (-0.005 [95%CI –0.009, -0.0001] p=0.04) in male patients, but not in female patients. Males had higher sC5b-C9 compared to females. Additionally, males with high C5 had a higher synovial fluid concentration of sC5b-C9 compared to males with low C5. No differences were found in females.ConclusionHigher synovial fluid C5 levels were associated with increased complement activation and decreased synovial vascularization in males but not in females with OA. Future studies should test whether synovial fluid complement activation suppresses synovial angiogenesis and identify mechanisms accounting for C5-related sex-differences in synovial fluid complement activation in patients with knee OA.

Contrast Induced Nephropathy: Efficacy of matched hydration and forced diuresis for prevention in patients with impaired renal function undergoing coronary procedures-CINEMA trial.

BackgroundMatched hydration and forced diuresis (MHFD) using the RenalGuard device has been shown to reduce contrast induced nephropathy (CIN) following coronary interventions.AimTo evaluate the potential benefits of a non-automated MHFD protocol compared to current hydration protocol in prevention of CIN in patients with CKD.MethodsA total of 1,205 patients were randomized to either non-automated MHFD group (n = 799) or intravenous hydration control group (n = 406). The MHFD group received 250 ml IV normal saline over 30 min before the coronary procedure followed by 0.5 mg/kg IV furosemide. Hydration infusion rate was manually adjusted to replace the patient's urine output. When urine output rate reached > 300 ml/h, patients underwent coronary procedure. Matched fluid replacement was maintained during the procedure and for 4-hour post-treatment. CIN was defined conventionally as ≥ 25% or ≥ 0.5 mg/dl rise in serum creatinine over baseline.ResultsCIN occurred in 121 of 1,205 (10.0%) patients in our study. With respect to the primary outcome, 64 (8.01%) of the MHFD patients developed CIN compared with 57 (14.04%) of the control group (p < 0.001).ConclusionsA non-automated MHFD protocol is an effective and safe method for the prevention of CIN in patients with CKD.

Results of the multicenter, prospective, randomised STRENGTH (Study To evaluate the use of RENalGuard to proTect patients at High risk of acute kidney injury) study

Abstract Aim Radio-contrast agents are widely used in coronary, peripheral and structural interventions. Use of these iodine-containing agents can be associated with contrast-induced acute kidney injury (CI-AKI) that can cause substantial morbidity and mortality. The RenalGuard system induces a forced diuresis with a matched hydration and has been shown beneficial in patients requiring coronary angiogram and PCI. Methods STRENGTH is a prospective, randomised (1:1), open-labeled, parallel-group, multicenter (10 centers in Germany and France) study where patients at high risk of CI-AKI were randomly assigned to RenalGuard® therapy or conventional strategy including preventive hydration before complex percutaneous cardiovascular intervention (PCI, peripheral and structural). In the RenalGuard arm, matched fluid replacement was started 60 minutes pre-procedure and maintained for up to 4 hours afterwards. Patients were given an initial i.v. bolus of up to 250 ml of normal saline over 30 minutes and then an i.v. bolus of furosemide (0.5 mg/kg). To be enrolled, patients had to have moderate to severe renal failure (defined as 15≤eGFR≤40 mL/min/m2) and a high-volume contrast requiring cardiovascular procedure (estimated contrast volume&amp;gt;3 times eGFR value). The main exclusion criterion was administration of iodine contrast media within 5 days before index procedure. The primary endpoint was CI-AKI defined as an increase in sCr ≥0.3 mg/dL or an increase of 25% of basal value or requiring dialysis within 5 days after procedure. The primary analysis for efficacy is performed in a modified intention-to-treat basis. The trial was designed and monitored by an independent CRO (Cardiovascular European Research Center, CERC, Massy, France). Results A total of 259 patients aged 79.1±8.8 yrs were included in the study. Among them, 129 were assigned to RenalGuard therapy and 130 to preventive saline hydration. Their mean baseline eGFR was 32 (25; 37) vs. 33 (25; 39) mL/min/m2, respectively (p=0.88). Total fluid intake volume within 24hrs before the procedure was 2383±1146 vs. 1386±842mL, respectively (p&amp;lt;0.0001). Procedure type was complex PCI (48%), TAVI (25%), peripheral intervention (18%), other structural intervention (9%) with no difference between groups (p=0.56). The total amount of contrast used for the procedure was 116.3±68.2mL in the RenalGuard arm vs. 104.1±56.7 mL in the conventional arm (p=0.26). A staged procedure was performed in 24 patients, including 16 in the RenalGuard and 8 in the control arm with a mean interval from the first intervention of 43±29 days and 24±19 days, respectively. For this second procedure, the total amount of contrast was 80±59 vs. 87±73mL. Conclusion The primary and secondary endpoints of the Study To evaluate the use of RENalGuard to proTect patients at High risk of CI-AKI comparing RenalGuard therapy to conventional hydration in 259 patients requiring complex percutaneous cardiovascular intervention will be presented. Funding Acknowledgement Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): CERC

Metabolomic similarities between bronchoalveolar lavage fluid and plasma in humans and mice

This observational study catalogues the overlap in metabolites between matched bronchoalveolar lavage fluid (BALF) and plasma, identifies the degree of congruence between these metabolomes in human and mouse, and determines how molecules may change in response to cigarette smoke (CS) exposure. Matched BALF and plasma was collected from mice (ambient air or CS-exposed) and humans (current or former smokers), and analyzed using mass spectrometry. There were 1155 compounds in common in all 4 sample types; fatty acyls and glycerophospholipids strongly overlapped between groups. In humans and mice, more than half of the metabolites present in BALF were also present in plasma. Mouse BALF and human BALF had a strong positive correlation with 2040 metabolites in common, suggesting that mouse models can be used to interrogate human lung metabolome changes. While power was affected by small sample size in the mouse study, the BALF metabolome appeared to be more affected by CS than plasma. CS-exposed mice showed increased plasma and BALF glycerolipids and glycerophospholipids. This is the first report cataloguing the metabolites present across mouse and human, BALF and plasma. Findings are relevant to translational studies where mouse models are used to examine human disease, and where plasma may be interrogated in lieu of BALF or lung tissue.

A prototype optical-CT system for PRESAGE 3D dosimeter readout

This work introduces the Duke Integrated-lens Optical Scanner (DIOS), a prototype optical-CT system designed for convenient and low-cost readout of PRESAGE 3D dosimeters. A key novelty of the DIOS is the incorporation of a multi-purpose light-collimating tank (the LC-tank). The LC-tank collimates light from a point source, maintains parallel ray geometry through a dosimeter mounted inside the tank, and refocuses emergent light onto a CCD detector. A second purpose is to dramatically reduce the amount of refractive matched fluid required in prior optical-CT scanners. This is achieved by substituting large quantities of refractive-matched fluid with solid RI-matched polyurethane. The advantages of DIOS include eliminating the need for expensive telecentric lenses, and eliminating the impracticality of large volumes of RI matched fluid. The DIOS is potentially more susceptible to stray-light artifacts. Preliminary phantom testing shows promising agreement between PRESAGE/DIOS readout and prior commissioned optical-CT scanners, as well as with Eclipse dose calculations.

Intraocular Pressure Is a Poor Predictor of Hydration Status following Intermittent Exercise in the Heat

Current hydration assessments involve biological fluids that are either compromised in dehydrated individuals or require laboratory equipment, making timely results unfeasible. The eye has been proposed as a potential site to provide a field-based hydration measure. The present study evaluated the efficacy and sensitivity of intraocular pressure (IOP) to assess hydration status. Twelve healthy males undertook two 150 min walking trials in 40°C 20% relative humidity. One trial matched fluid intake to body mass loss (control, CON) and the other had fluid restricted (dehydrated, DEH). IOP (rebound tonometry) and hydration status (nude body mass and serum osmolality) were determined every 30 min. Body mass and serum osmolality were significantly (p < 0.05) different between trials at all-time points following baseline. Body mass losses reached 2.5 ± 0.2% and serum osmolality 299 ± 5 mOsmol.kg−1 in DEH. A significant trial by time interaction was observed for IOP (p = 0.042), indicating that over the duration of the trials IOP declined to a greater extent in the DEH compared with the CON trial. Compared with baseline measurements IOP was reduced during DEH (150 min: −2.7 ± 1.9 mm Hg; p < 0.05) but remained stable in CON (150 min: −0.3 ± 2.4 mm Hg). However, using an IOP value of 13.2 mm Hg to predict a 2% body mass loss resulted in only 57% of the data being correctly classified (sensitivity 55% and specificity 57%). The use of ΔIOP (−2.4 mm Hg) marginally improved the predictive ability with 77% of the data correctly classified (sensitivity: 55%; specificity: 81%). The present study provides evidence that the large inter-individual variability in baseline IOP and in the IOP response to progressive dehydration, prevents the use of IOP as an acute single assessment marker of hydration status.

Neuromodulation of fast-spiking and non-fast-spiking hippocampal CA1 interneurons by human cerebrospinal fluid.

How the brain extracellular fluid influences the activity of GABAergic interneurons in vivo is not known. This issue is examined in the hippocampal brain slice by comparing GABAergic interneuron activity in human versus artificial cerebrospinal fluid. Human cerebrospinal fluid (hCSF) substantially increases the excitability of fast-spiking and non-fast-spiking CA1 interneurons. CA1 pyramidal cells are even more strongly excited by hCSF. The tonic excitation of pyramidal cells, in combination with an increased responsiveness of interneurons to excitatory input, is likely to promote the generation of synchronized network activity in the hippocampus. GABAergic interneurons intricately regulate the activity of hippocampal and neocortical networks. Their function in vivo is likely to be tuned by neuromodulatory substances in the brain extracellular fluid. However, in vitro investigations of GABAergic interneuron function do not account for such effects, as neurons are kept in artificial extracellular fluid. To examine the neuromodulatory influence of brain extracellular fluid on GABAergic activity, we recorded from fast-spiking and non-fast-spiking CA1 interneurons, as well as from pyramidal cells, in the presence of human cerebrospinal fluid (hCSF), using a matched artificial cerebrospinal fluid (aCSF) as control. We found that hCSF increased the frequency of spontaneous firing more than twofold in the two groups of interneurons, and more than fourfold in CA1 pyramidal cells. hCSF did not affect the resting membrane potential of CA1 interneurons but caused depolarization in pyramidal cells. The increased excitability of interneurons and pyramidal cells was accompanied by reductions in after-hyperpolarization amplitudes and a left-shift in the frequency-current relationships. Our results suggest that ambient concentrations of neuromodulators in the brain extracellular fluid powerfully influence the excitability of neuronal networks.

Novel relationships between B12, folate and markers of inflammation, oxidative stress and NAD(H) levels, systemically and in the CNS of a healthy human cohort

Objective: To evaluate the relationship between folate, cobalamin (Cbl), and homocysteine (Hcy), and markers of inflammation and oxidative stress within the periphery and central nervous system (CNS) of a healthy human cohort.Methods: Thirty-five matched cerebrospinal fluid (CSF) and plasma samples were collected from consenting participants who required a spinal tap for the administration of anaesthetic. Plasma concentrations of Hcy and both plasma and CSF levels of folate, Cbl, nicotinamide adenine dinucleotide (NAD(H)) and markers of inflammation (interleukin-6, IL-6), and oxidative stress (F2-isoprostanes, 8-hydroxy-2′-deoxyguanosine (8-OHdG), and total antioxidant capacity (TAC)) were quantified.Results: In the peripheral circulation, positive associations were observed between plasma folate and Cbl, and plasma TAC (P ≤ 0.01; P ≤ 0.01) and plasma NAD(H) (P ≤ 0.05; P ≤ 0.05) levels, respectively. Plasma folate was inversely associated with plasma Hcy concentrations (P ≤ 0.05); however, no statistically significant relationships were observed between plasma Hcy and plasma markers of inflammation, oxidative stress, or [NAD(H)].Within the CNS plasma Hcy correlated positively with CSF IL-6 (P ≤ 0.01) and negatively with CSF NAD(H) (P ≤ 0.05) concentrations. An inverse association was observed between CSF folate and CSF levels of IL-6 (P ≤ 0.05). Unexpectedly, a positive association between CSF Cbl and CSF 8-OHdG levels was also found (P ≤ 0.01).Discussion: These results indicate that folate and Cbl concentrations may influence the levels of oxidative damage, inflammation, and NAD(H), both systemically and within the CNS.

SU‐E‐T‐294: Simulations to Investigate the Feasibility of ‘dry’ Optical‐CT Imaging for 3D Dosimetry

Purpose:To perform simulations investigating the feasibility of “dry” optical‐CT, and determine optimal design and scanning parameters for a novel dry tank telecentric optical‐CT 3D dosimetry system. Such a system would have important advantages in terms of practical convenience and reduced cost.Methods:A Matlab based ray‐tracing simulation platform, ScanSim, was used to model a telecentric system with a polyurethane dry tank, cylindrical dosimeter, and surrounding fluid. This program's capabilities were expanded for the geometry and physics of dry scanning. To categorize the effects of refractive index (RI) mismatches, simulations were run for several dosimeter (RI = 1.5−1.48) and fluid (RI = 1.55−1.33) combinations. Additional simulations examined the effect of increasing gap size (1–5mm) between the dosimeter and tank wall, and of changing the telecentric lens tolerance (0.5°−5°). The evaluation metric is the usable radius; the distance from the dosimeter center where the measured and true doses differ by less than 2%.Results:As the tank/dosimeter RI mismatch increases from 0–0.02, the usable radius decreases from 97.6% to 50.2%. The fluid RI for matching is lower than either the tank or dosimeter RI. Changing gap sizes has drastic effects on the usable radius, requiring more closely matched fluid at large gap sizes. Increasing the telecentric tolerance through a range from 0.5°–5.0° improved the usable radius for every combination of media.Conclusion:Dry optical‐CT with telecentric lenses is feasible when the dosimeter and tank RIs are closely matched (&lt;0.01 difference), or when data in the periphery is not required. The ScanSim tool proved very useful in situations when the tank and dosimeter have slight differences in RI by enabling estimation of the optimal choice of RI of the small amount of fluid still required. Some spoiling of the telecentric beam and increasing the tolerance helps recover the usable radius.

Prevention of Contrast Nephropathy by Furosemide With Matched Hydration: The MYTHOS (Induced Diuresis With Matched Hydration Compared to Standard Hydration for Contrast Induced Nephropathy Prevention) Trial

This study investigated the effect of furosemide-forced diuresis and intravenous saline infusion matched with urine output, using a novel dedicated device designed for contrast-induced nephropathy (CIN) prevention. CIN is a frequent cause of acute kidney injury associated with increased morbidity and mortality. A total of 170 consecutive patients with chronic kidney disease (CKD) undergoing coronary procedures were randomized to either furosemide with matched hydration (FMH group, n = 87) or to standard intravenous isotonic saline hydration (control group; n = 83). The FMH group received an initial 250-ml intravenous bolus of normal saline over 30 min followed by an intravenous bolus (0.5 mg/kg) of furosemide. Hydration infusion rate was automatically adjusted to precisely replace the patient's urine output. When a urine output rate >300 ml/h was obtained, patients underwent the coronary procedure. Matched fluid replacement was maintained during the procedure and for 4 h post-treatment. The definition of CIN was a ≥25% or ≥0.5 mg/dl rise in serum creatinine over baseline. In the FMH group, no device- or therapy-related complications were observed. Four (4.6%) patients in the FMH group developed CIN versus 15 (18%) controls (p = 0.005). A lower incidence of cumulative in-hospital clinical complications was also observed in FMH-treated patients than in controls (8% vs. 18%; p = 0.052). In patients with CKD undergoing coronary procedures, furosemide-induced high urine output with matched hydration significantly reduces the risk of CIN and may be associated with improved in-hospital outcome. (Induced Diuresis With Matched Hydration Compared to Standard Hydration for Contrast Induced Nephropathy Prevention [MYTHOS]; NCT00702728).

Letter to the Editor

Dear Editor:I read with great interest the recent article by Anastasiou CA, Kavouras SA, Arnaoutis G, et al (and supported by the Gatorade Sport Science Institute) entitled “Sodium Replacement and Plasma Sodium Drop During Exercise in the Heat When Fluid Intake Matches Fluid Loss” (J Athl Train. 2009;44(2):117–123). In this letter, I propose further discussion and an alternative interpretation of their findings.A purpose of the study was to examine the ability of several beverages (high [Na+], low [Na+], placebo, and distilled water) to maintain serum sodium concentrations when fluid supplementation matched fluid lost to sweating. The authors concluded that even small amounts of sodium (19 mmol/L) in replenished fluid were able to prevent the decrease in plasma sodium observed when sodium-free fluids were ingested during prolonged exercise. An alternative interpretation of the results is that sodium-containing beverages better attenuated the drop in serum [Na+] during prolonged exercise in a state of overhydration.In citing Greenleaf and Sargent's seminal 1965 work,1 the authors noted that “thirst perception is an insufficient means to match fluid losses during exercise.” This is true, although the goal of exactly matching fluid losses during exercise is unclear. It is well established that exercising humans replace a fraction (20%–70%) of sweat losses when given ad libitum access to fluids.2–4 Recent work has demonstrated maintenance of total body water despite weight loss of 4%–5% during the prolonged exercise of an ultradistance triathlon.5 The correlation with body-weight loss and maintenance of physiologic [Na+] is well established.6 Sharwood et al7 demonstrated that large losses of body weight in an ultradistance triathlon correlated with neither decreased performance nor likelihood of presenting to medical stations. The recommendation to replace all weight loss with fluid volume is not supported by these studies.The authors also noted that the findings of their study, along with those of Vrijens and Rehrer,8 contrast with those of several other investigators9–11 as to the ability of sodium-containing fluids to maintain plasma volume and [Na+]. The difference is to be found in the methods: in the latter 3 studies, ad libitum hydration was offered to participants, whereas in the former 2, participants were overhydrated by replacing sweat losses.The authors concluded that “when sweating is excessive and the goal is to restore fluid losses during exercise, special attention should be paid to the replenishment of sodium.” The data presented indicate that the goal of rehydration during exercise is not to replenish fluid losses but rather to maintain [Na+]. This is best accomplished by drinking to thirst,12–16 does not require sodium supplementation,9,17 and is usually accompanied by mild to moderate weight loss.6 It is my hope that critical review of hydration, as presented in this letter, will influence more runners to avoid the complications associated with overhydration.

Abstract 4843: Furosemide-induced Diuresis With Matched Replacement of Intravascular Volume Compared to Standard Hydration for Contrast-induced Nephropathy Prevention: The Mythos Trial

Hypothesis. We investigated the effect of a new preventive strategy strategy for contrast-induced nephropathy (CIN) based on a dedicated device (RenalGuard; PLC Medical System Inc., USA). The system is capable of delivering i.v. saline solution to a patient in an amount matched to the volume of urine produced after an i.v. bolus of furosemide. The aim of the study was to evaluate if furosemide-induced high-volume diuresis with concurrent maintenance of intravascular volume may prevent CIN. Methods . To date, 63 chronic kidney disease (CKD) patients (eGFR&lt;60 ml/min/1.73 m 2 ) undergoing percutaneous coronary interventions (PCI) were enrolled in the MYTHOS trial. They were randomized to matched hydration (RenalGuard group, n=30) or to i.v. isotonic saline hydration (control group; n=33) at a rate of 1 ml/kg/hour for 12 hours before and after PCI. Matched fluid replacement was started approximately 90 minutes pre-PCI, maintained during catheterization, and for up to 4 hours afterwards. Patients were given an initial i.v. bolus of 250 ml of normal saline over 30 minutes and then an i.v. bolus of furosemide (0.5 mg/kg). The RenalGuard measures the patient’s urine volume and then automatically adjusts the infusion pump rate to precisely replace the measured urine output in real time. When a &gt;300 ml/hour urine output rate was obtained, patients underwent PCI. CIN was defined as a ≥0.5 mg/dl or ≥25% rise in serum creatinine over baseline. Results . Overall, the mean eGFR was 40±9 ml/min/1.73 m 2 . The mean contrast volume was 190±92 ml in RenalGuard group and 212±118 ml in controls (P=0.4). In RenalGuard group, urine output ranged from 319 to 1788 ml/hr (mean 830±322 ml/hr). There were no serious device-or therapy-related complications, including clinically significant electrolyte changes (asymptomatic ipokalemia was corrected in 1 case). CIN occurred in no patient (0%) of the RenalGuard group and in 5 (15%) controls (P=0.03). Two controls (6%) required temporary renal replacement therapy. Conclusions. These preliminary results indicate that furosemide-induced high urine output with maintenance of intravascular volume through matched hydration can be safely obtained with the RenalGuard system and may reduce the risk of CIN in CKD patients undergoing PCI.

Hydration Status, Sweat Rates, and Rehydration Education of Youth Football Campers

Previous field research has not identified sweat rates (SR), fluid consumption (FC), or the efficacy of an educational intervention (EI) for youth during football camp. To measure hydration status and rehydration performance and examine EL using these data. Observational with EI randomized comparison. Thirty-three boys (mean +/- SD: 12 +/- 2 y, 52.9 +/- 13.6 kg, 156 +/- 12 cm) volunteered during a 5-d camp with 3 (-2-h) sessions per day (WBGT: 25.6 +/- 0.5 degrees C). Hydration status, SR, and FC. Urine osmolality averaged 796 +/- 293 mOsm/L for days 2-5. Game SR (1.30 +/- 0.57 L/h) was significantly greater than practice SR (0.65 +/- 0.35 L/h; P = .002). Subjects dehydrated during free time but matched fluid losses with FC (0.76 +/- 0.29 L/h) during football activities. Subjects arrived at camp hypohydrated and maintained this condition. They matched FC and SR during, but dehydrated when not playing, football. This may impair recovery and subsequent performance. Hydration EI seemed to have a positive influence on hydration practices.

Stability of two-layer viscoelastic plane Couette flow past a deformable solid layer: implications of fluid viscosity stratification

The linear stability of two-layer plane Couette flow of upper-convected Maxwell (UCM) fluids of thicknesses ( 1 − β ) R and β R , with viscosities μ a and μ b , and relaxation times τ a and τ b past a linear viscoelastic solid layer (of thickness H R , shear modulus G , and viscosity η w ) is determined using a combination of low wavenumber asymptotic analysis and a numerical method. The asymptotic analysis is used to determine the effect of the deformable solid layer on the two-fluid interfacial instability due to elasticity and viscosity stratification in the low wavenumber limit. The asymptotic results show that as the solid layer is made more deformable, the two-fluid interfacial instability could be completely stabilized in the long wave limit, when the non-dimensional parameter Γ = V μ b / ( G R ) ∼ O ( 1 ) exceeds a certain critical value. Here, V is the dimensional velocity of the moving top plate. In marked contrast with the previous results obtained for matched fluid viscosities [V. Shankar, J. Non-Newtonian Fluid Mech., 117 (2004) 163], the present asymptotic results show that the stabilizing or destabilizing nature of the solid layer on the two-fluid interfacial instability is controlled only by the fluid viscosity ratio and is independent of the relaxation times of the two UCM fluids. In general, it is found that the solid layer has a stabilizing effect for β < 0.5 , μ r < 1 and β > 0.5 , μ r > 1 , while it has both stabilizing and destabilizing effects (depending on its thickness H, and the fluid thickness ratio β ) for β > 0.5 , μ r < 1 and β < 0.5 , μ r > 1 . In the absence of the solid layer, the two-fluid interfacial mode is unstable or stable depending on the ratio of relaxation times between the two fluids and the thickness ratio β . It is thus possible, under appropriate combinations of relaxation times, viscosities, and thicknesses of the two fluids, to stabilize (destabilize) the two-fluid interfacial mode by the deformable solid layer while it is unstable (stable) in the absence of the solid layer. Another important result from the present low wavenumber (denoted by k ) analysis is that the non-dimensional solid elasticity parameter Γ required to stabilize or destabilize the two-fluid interfacial mode is an O ( 1 ) quantity in the low- k -limit when μ a ≠ μ b , with numerical values of Γ significantly smaller than 1 for H ∼ O ( 1 ) . Whereas when μ a = μ b our asymptotic analysis (as well as the earlier study) shows that Γ ∝ k − 1 for k ≪ 1 . The results from the low- k -asymptotic analysis are continued numerically to finite values of k and Reynolds number, and the numerical results confirm that the stabilization of the two-fluid interfacial mode by the solid layer extends to finite values of k . However, for short wavelength fluctuations with k ≫ 1 , the fluid velocity perturbations are localized near the two-fluid interface, so the solid layer has no effect on these fluctuations. These short wavelength unstable modes can be stabilized only by the presence of a sufficiently strong interfacial tension between the two fluids. Thus, the present study shows that the viscosity mismatch between the two fluids profoundly changes the stabilizing or destabilizing effect of the deformable solid layer on the two-fluid interfacial mode in viscoelastic fluids when compared to the conclusions reached using matched fluid viscosities.

Cytokine profile in serum and synovial fluid of arthritis patients with Chlamydia trachomatis infection.

Chlamydia trachomatis (Ct)-induced arthritis (CtIA) is characterized by persistent Ct infection, which stimulates secretion of cytokines in vitro. We therefore investigated whether CtIA patients have a unique cytokine profile in synovial fluid or serum in vivo. Because underlying Ct infection is overlooked in a high percentage of patients with initially diagnosed undifferentiated oligoarthritis (UOA), we examined whether determination of cytokines might also be of diagnostic relevance for this arthritis form. Matched serum and synovial fluid specimens from 26 patients with CtIA were analyzed and compared to those from 34 patients with UOA in whom Ct infection was excluded and those of nine patients with rheumatoid arthritis (RA). In 15 CtIA patients, Ct DNA from synovial fluid could be amplified by polymerase chain reaction. The following cytokine or cytokine antagonists were measured by enzyme-linked immunosorbent assay: interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, IL-6, IL-1 receptor antagonist, and soluble TNF receptor p75. No statistically significant differences in cytokine levels between patients with CtIA or the other arthritis forms were detected. Also, comparison between CtIA patients with (n = 17) and without Chlamydia DNA (n = 9) in synovial fluid revealed no significant differences for these cytokines. Cytokine levels in serum and synovial fluid were not different between CtIA, UOA without Ct infection, and RA patients. The intracellular presence of Ct was not associated with a specific profile of these cytokines in vivo.

Working memory, intelligence and knowledge base in adult persons with intellectual disability

Previous studies have suggested that performance in working memory (WM) tasks is deficient in all etiologies and at all levels of intellectual disability (ID). Knowledge about WM structure, cognitive processes reflected in WM tasks, or the long-term memory contribution to WM capacity in ID is, however, not satisfactory. In the present study, WM capacity, WM task requirements, as well as effects between WM, skills, knowledge base, and intelligence were explored in two groups with matched fluid intelligence: adult persons with ID and normally developing children aged 3–6 years. The ID Group performed equally well as the children in WM tasks based on familiar semantic information and were significantly better on all measures reflecting skills and knowledge base. The Child Group performed better in phonological and visuo-spatial WM tasks including nonsemantic information, respectively. In particular, it appeared that the groups differed in their WM performance although they were matched for fluid intelligence. We hypothesize that the ID Group depended more on knowledge support from long-term memory whereas the Child Group could benefit more from efficient online WM processes.