Stopped-flow Research Articles

The deleterious effect of pyrollic-nitrogen on the substitution reactivity of tridentate N^C^N platinum(II) complexes. A kinetic and mechanistic study

AbstractThe rate of substitution of the chloride ligand in 1,3-bis(pyridyl)benzene platinum(II) chloride (Pt1), 1,3-bis(N-pyrazolyl)benzene platinum(II) chloride (Pt2), 1,3-bis(8-quinolyl)benzene platinum(II) chloride (Pt3), and 1,3-bis(7-azaindolyl)benzene platinum(II) chloride (Pt4) by three neutral nucleophiles with different steric demands, thiourea (Tu), N,N’-dimethylthiourea (Dmtu), and N,N,N,’N-tetramethylthiourea (Tmtu), was studied under pseudo-first-order conditions in methanol. The investigation was performed as a function of concentration and temperature using stopped-flow and UV–visible spectrophotometric techniques. The observed pseudo-first-order rate constants for substitution obeyed the rate law: . The reactivity of the rigid planar five-membered chelate complexes (Pt1 and Pt2) is influenced by the push and pull effect of the σ/π-character of the cis moieties, while in the six-membered complexes (Pt3 and Pt4) it is dependent on their structural topology and electronic features. The study ...

Early stage kinetics of polyelectrolyte complex coacervation monitored through stopped-flow light scattering.

Polyelectrolyte complexes (PECs) between poly(acrylic acid) (PAA) and poly(diallyldimethylammonium chloride) (PDADMAC), a model system forming coacervate particles via electrostatic interaction at pH 10, were prepared by a stopped-flow (SF) fast mixing technique at different mixing charge ratios (z) and ionic strengths. Both PEC final morphologies prepared by either SF or manual one-shot mixing are similar at bench time. In situ light scattering combined with the SF technique pointed-out, however, the presence of three distinct early stage kinetic behaviors in the formation of PECs. The first stage observed at low z is ascribed to the relaxation/reorganization of soluble PECs. At higher z or in the presence of salt, a second stage is found corresponding to the aggregation and/or rearrangement of small soluble PECs into larger structures. Redistribution of excess charges among those PECs produces some neutral condensed coacervate droplets as well, coexisting with PECs in a wide range of mixing ratios. Finally, a last process featured with bell-shaped curves indicates the full coacervation that quickens while approaching charge neutrality and/or at higher ionic strength.

Acquired deficiency of tafazzin in the adult heart: Impact on mitochondrial function and response to cardiac injury

The content and composition of cardiolipin (CL) is critical for preservation of mitochondrial oxidative phosphorylation (OXPHOS) and inner membrane integrity. Tafazzin (Taz) is an enzyme responsible for remodeling of immature CL containing mixed acyl groups into the mature tetralinoleyl form (C18:2)4-CL. We hypothesized that acquired defects in Taz in the mature heart would impact remodeling of CL and augment cardiac injury. The role of acquired Taz deficiency was studied using the inducible Taz knockdown (TazKD) mouse. Taz-specific shRNA is induced by doxycycline (DOX). One day of DOX intake decreased Taz mRNA in the heart to 20% vs. DOX-treated WT. Knockdown was initiated at an adult age and was stable during long term feeding. CL phenotype was assessed by (C18:2)4-CL content and was reduced 40% vs. WT at two months of DOX. TazKD showed increased production of reactive oxygen species and increased susceptibility to permeability transition pore opening at baseline. However, OXPHOS measured using the rate of oxygen consumption was unchanged in the setting of acquired Taz deficiency. Infarct size, measured in isolated buffer-perfused Langendorff hearts following 25min. Stop flow ischemia and 60min. Reperfusion was not altered in TazKD hearts. Thus, impaired Taz-function with onset at adult age does not enhance susceptibility to ischemia-reperfusion injury.

Synthesis of Cell-Adhesive Anisotropic Multifunctional Particles by Stop Flow Lithography and Streptavidin-Biotin Interactions.

Cell-adhesive particles are of significant interest in biotechnology, the bioengineering of complex tissues, and biomedical research. Their applications range from platforms to increase the efficiency of anchorage-dependent cell culture to building blocks to loading cells in heterogeneous structures to clonal-population growth monitoring to cell sorting. Although useful, currently available cell-adhesive particles can accommodate only homogeneous cell culture. Here, we report the design of anisotropic hydrogel microparticles with tunable cell-adhesive regions as first step toward micropatterned cell cultures on particles. We employed stop flow lithography (SFL), the coupling reaction between amine and N-hydroxysuccinimide (NHS) and streptavidin-biotin chemistry to adjust the localization of conjugated collagen and poly-L-lysine on the surface of microscale particles. Using the new particles, we demonstrate the attachment and formation of tight junctions between brain endothelial cells. We also demonstrate the geometric patterning of breast cancer cells on particles with heterogeneous collagen coatings. This new approach avoids the exposure of cells to potentially toxic photoinitiators and ultraviolet light and decouples in time the microparticle synthesis and the cell culture steps to take advantage of the most recent advances in cell patterning available for traditional culture substrates.

A complementary method to CD4 counting: measurement of CD4+/CD8+ T lymphocyte ratio in a tandem affinity microfluidic system.

We describe a tandem affinity microfluidic separation that measures the ratio of CD4+/CD8+ T lymphocytes from blood samples. It is performed by injecting 2μL of lysed blood samples at 1800-2700cellsμL(-1) into a microfluidic device containing two serially linked affinity regions, followed with a stop flow incubation that captures CD4+/CD8+ T lymphocytes on the corresponding affinity regions. Fluorophore conjugated antibodies are then injected at a controlled shear stress of 1.7dyn cm(-2) to label target cells while eluting non-specific cells; and at last the CD4/CD8 ratio is calculated after the cell enumeration. The ratio of CD4+/CD8+ T lymphocytes achieved by our tandem affinity microfluidic system was in close agreement with that performed using conventional flow cytometry (R (2) = 0.97) over a wide range (0.4-2.5) that covered the reference values from immune deficient patients to healthy people. This approach may represent an inexpensive and powerful tool in diagnosis of immunodeficiency disorders including HIV or mycobacterium tuberculosis.

Water residence time and pesticide removal in pilot-scale wetlands

The use of agricultural pesticides may lead to environmental contamination. Constructed wetlands (CWs) are often recommended for decreasing non-point source pollution by pesticides. The aim of this study was to evaluate the influences of water residence time (WRT) on the effectiveness of two CWs for decreasing pollution in drainage water at the pilot scale. Thus, two successive charge/discharge steps were conducted successively with high and low flows before conducting a step with no flow. For both pilot experiments, the measured effectiveness was between 22 and 100% of the applied quantities of the five pesticides. These results were correlated with the physicochemical properties of the pesticides, particularly their adsorption and desorption capacities. In addition, the pilot scale wetlands were less effective during short WRT (from 15.2 to 100%) than during long WRT (from 17.8 to 100%), despite the greater remobilisation observed during the discharge steps with low flows. After stopping flow, the DT50 values of the pesticides in the aqueous phase were less than 4 days in the two pilot wetlands, likely due to their rapid transfer to the solid phase (soil or straw). In addition, the DT50 values measured in the solid phases ranged from 3.8 days to more than one year. Thus, the WRT must be optimised in the CW by maintaining vegetation or installing weirs, to favour retention processes (sorption, sedimentation) during the drainage periods (October to May). Next, the pesticides stored in the solid phase could be subjected to degradation processes, particularly when moisture, residence times and temperature conditions are favourable (summer).

Abstract P011: Source and Catabolism Sites of the Cardio-renal Protective Peptide N-Acetyl-Seryl-Aspartyl-Lysyl-Proline (Ac-SDKP)

Ac-SDKP is a natural tetrapeptide with anti-fibrotic and anti-inflammatory properties in vascular, myocardial and kidney tissues. It is degraded by angiotensin converting enzyme (ACE) and treatment with ACE inhibitors increases its plasma levels. However the main sites of Ac-SDKP production and catabolism are unknown. Thus, the aim of this study was to determine the source and catabolism sites of Ac-SDKP. Ac-SDKP was measured in brain, thymus, lungs, heart, spleen, kidney, liver, intestine, and bone marrow from male 200-250 gr Sprague Dawley rats. Samples from arterial blood delivered to and venous blood exiting from kidney, spleen, intestine, liver, and lungs were obtained, and the vein to arterial (V-A) plasma levels differences were calculated as an index of organ production or elimination. Additionally, urinary Ac-SDKP excretion over 24 hrs and Ac-SDKP renal clearance were measured. Inulin clearance was also determined. The Stop Flow technique was performed to evaluate the renal handling of Ac-SDKP in different segments of the nephron. The greatest amounts of Ac-SDKP were found in Thymus, Spleen and Bone marrow (111.3±9; 92.2±24; 70.3±17 pmoles/mg of protein respectively), while the lowest values were found in brain, large intestine and heart (10.7±6; 14.8±6 ;19.8±7; pmoles/mg of protein, respectively). Ac-SDKP is secreted by different organs into the circulating blood. The highest V-A difference was found in the spleen (15.2±7 nM), reflecting its production, while the lowest V-A differences was observed in the lungs (-1.2±3.7 nM), reflecting a high degradation of Ac-SDKP in this tissue. No V-A differences were found in kidney (0.98±7 nM). It was not possible to obtain venous samples from Thymus or Bone marrow. The renal clearance of Ac-SDKP was 0.15 ml/min/100g body weight, equivalent to a fractional excretion of 14.5%. The stop flow technique showed the highest Ac-SDKP levels in the distal part of the nephron, while the proximal segments showed the lowest (11 Vs. 4.2 Ac-SDKP/Inulin ratio). In conclusion, Ac-SDKP production occurs mainly in lymphoid organs. Expectedly, high Ac-SDKP degradation was observed in the lungs. In the kidney Ac-SDKP is filtered, probably degraded in the proximal tubule and secreted in the distal tubule.

Abstract P033: Acute Intravenous Glucose Injection Inhibits Tubuloglomerular Feedback and Increase Glomerular Filtration Rate

Hyperfiltration is considered a risk factor for diabetic nephropathy, but the mechanism for alterations in glomerular filtration rate (GFR) in diabetes has not been clarified. Nitric oxide synthase 1 (NOS1) highly expresses in the macula densa (MD) and NO inhibits tubuloglomerular feedback (TGF). TGF is one of the major mechanisms for glomerular filtration rate (GFR) regulation. It is not clear whether glucose itself filtered into the tubules has any effect on GFR. We hypothesized the glucose enhances NOS1 activity in the MD, which blunts TGF and increases GFR. First, we measured GRF in conscious mice by plasma FITC-inulin clearance. Three min after an intravenous infusion of 50μl of 4M glucose in wild type mice, GFR was increased by 19.1% from 236±9.7 to 281±13.4 μl/min. Intravenous saline infusion had no effect on GFR. NO generation by the MD was then measured in isolated perfused juxtaglomerular apparatus with fluorescent probe DAF-2DA. In response to an increase in tubular glucose concentration from 0 to 300 mg/dl, NO production was increased by 78.4%. TGF, assessed in vivo by measuring the change in proximal tubular stop flow pressure (Δ) induced by an increase of perfusion rate in late proximal tubules from 0 to 40 nl/min, was significantly blunted from 6.5±0.9 to 5.0±1.6 mmHg when tubular perfusate glucose concentration was increased 0 to 300 mg/dl. To determine whether the glucose-induced changes were mediated by NOS1 in MD, we repeated the experiments in MD specific NOS1 KO (MD-NOS1KO) mice. Intravenous glucose infusion did not significantly increase GRF (from 203±15.7 to 220±6.9 μl/min) in the KO mice. Elevating glucose content in tubular perfusate did not alter the TGF response (Δ was from 7.8±1.3 to 7.3±2.1 mmHg) in MD-NOS1KO mice. We concluded that increase of tubular glucose concentration increases GFR by inhibiting TGF response, which is mediated by NO production from NOS1 in the MD.

Synthesis of Nonspherical Microcapsules through Controlled Polyelectrolyte Coating of Hydrogel Templates.

We report a simple approach to fabricate custom-shape microcapsules using hydrogel templates synthesized by stop flow lithography. Cargo-containing microcapsules were made by coating hydrogel particles with a single layer of poly-l-lysine followed by a one-step core degradation and capsule cross-linking procedure. We determined appropriate coating conditions by investigating the effect of pH, ionic strength, and prepolymer composition on the diffusion of polyelectrolytes into the oppositely charged hydrogel template. We also characterized the degradation of the templating core by tracking the diffusivity of nanoparticles embedded within the hydrogel. Unlike any other technique, this approach allows for easy fabrication of microcapsules with internal features (e.g., toroids) and selective surface modification of Janus particles using any polyelectrolyte. These soft, flexible capsules may be useful for therapeutic applications as well as fundamental studies of membrane mechanics.

Rate-determining Step of Flap Endonuclease 1 (FEN1) Reflects a Kinetic Bias against Long Flaps and Trinucleotide Repeat Sequences

Flap endonuclease 1 (FEN1) is a structure-specific nuclease responsible for removing 5'-flaps formed during Okazaki fragment maturation and long patch base excision repair. In this work, we use rapid quench flow techniques to examine the rates of 5'-flap removal on DNA substrates of varying length and sequence. Of particular interest are flaps containing trinucleotide repeats (TNR), which have been proposed to affect FEN1 activity and cause genetic instability. We report that FEN1 processes substrates containing flaps of 30 nucleotides or fewer at comparable single-turnover rates. However, for flaps longer than 30 nucleotides, FEN1 kinetically discriminates substrates based on flap length and flap sequence. In particular, FEN1 removes flaps containing TNR sequences at a rate slower than mixed sequence flaps of the same length. Furthermore, multiple-turnover kinetic analysis reveals that the rate-determining step of FEN1 switches as a function of flap length from product release to chemistry (or a step prior to chemistry). These results provide a kinetic perspective on the role of FEN1 in DNA replication and repair and contribute to our understanding of FEN1 in mediating genetic instability of TNR sequences.

When Solids Stop Flow Chemistry in Commercial Tubing

Flow chemistry has emerged as the enabling field of high-throughput, data-driven discovery, and process chemistry, yet solids handling remains its key challenge. Insoluble salt by-products can stop flow, fluctuate reagent concentrations in reactors, and cost unexpected time and materials consumptions. The clogging of perfluoroalkoxy (PFA) tubing, stainless steel (SS) tubing, and a silicon microreactor by NaCl during a Pd-catalyzed amination using XPhos ligand was each studied. Our goal of understanding the appropriate reactor design provides in-depth analyses of constriction and mechanical entrapment. Calculations of Stokes number (St)>1 revealed that NaCl particle depositions were independent of the reactor materials. Analyses of the clogging time’s dependence on the residence time (τ) and particle volume fraction (ϕ) discovered commercial tubing to be inadequate for the decoupling of the kinetics. The results prescribe why fabricated microreactors with on-chip analytics, particle formations and dissolut...

Fetal tubuloglomerular feedback in an ovine model of mild maternal renal disease.

Fetuses of pregnant ewes, which were subtotally nephrectomized prior to mating, were studied to assess whether mild maternal renal impairment would affect fetal tubuloglomerular feedback (TGF) under control conditions and after the inhibition of macula densa-derived nitric oxide (NO). Based on previous observations we hypothesized that, the TGF curve of fetuses of subtotally nephrectomized (STNx) ewes would resemble that of a volume expanded fetus with a high production rate of NO and that inhibition of neuronal nitric oxide synthase (nNOS) would increase the sensitivity of the TGF system in these fetuses. Renal function studies were performed on anaesthetized fetal sheep (133–140 days gestation; term ∼150 days; Isoflurane 2–4% in oxygen). Fetuses were removed from the uterus and placed in a water bath (39.5°C) while maintaining umbilical blood flow. Glomerular filtration rate (GFR) and urine flow rate were markedly increased in fetuses of STNx ewes compared to fetuses of untreated ewes. Interestingly, and contrary to our hypothesis, the fetuses of STNx ewes exhibited no difference in TGF sensitivity in the presence or absence of 7-nitroindazole (7NI; nNOS inhibitor), compared to fetuses of untreated ewes, although sensitivity and reactivity increased in both groups after 7NI. There was however, a decrease in the stop flow pressure and net filtration pressure with an increase in the filtration coefficient (Kf). These factors suggest that maternal renal impairment drives the glomerular hypertrophy which has previously been found to be present in the neonatal period. Thus, we conclude that at ∼138 days gestation, the fetal kidney has matured functionally and fetuses of STNx ewes are able to maintain fluid and electrolyte homeostasis even in the presence of increased transplacental flux.

Safety of intracoronary infusion of 20 million C-kit positive human cardiac stem cells in pigs.

BackgroundThere is mounting interest in using c-kit positive human cardiac stem cells (c-kitpos hCSCs) to repair infarcted myocardium in patients with ischemic cardiomyopathy. A recent phase I clinical trial (SCIPIO) has shown that intracoronary infusion of 1 million hCSCs is safe. Higher doses of CSCs may provide superior reparative ability; however, it is unknown if doses >1 million cells are safe. To address this issue, we examined the effects of 20 million hCSCs in pigs.MethodsRight atrial appendage samples were obtained from patients undergoing cardiac surgery. The tissue was processed by an established protocol with eventual immunomagnetic sorting to obtain in vitro expanded hCSCs. A cumulative dose of 20 million cells was given intracoronarily to pigs without stop flow. Safety was assessed by measurement of serial biomarkers (cardiac: troponin I and CK-MB, renal: creatinine and BUN, and hepatic: AST, ALT, and alkaline phosphatase) and echocardiography pre- and post-infusion. hCSC retention 30 days after infusion was quantified by PCR for human genomic DNA. All personnel were blinded as to group assignment.ResultsCompared with vehicle-treated controls (n=5), pigs that received 20 million hCSCs (n=9) showed no significant change in cardiac function or end organ damage (assessed by organ specific biomarkers) that could be attributed to hCSCs (P>0.05 in all cases). No hCSCs could be detected in left ventricular samples 30 days after infusion.ConclusionsIntracoronary infusion of 20 million c-kit positive hCSCs in pigs (equivalent to ~40 million hCSCs in humans) does not cause acute cardiac injury, impairment of cardiac function, or liver and renal injury. These results have immediate translational value and lay the groundwork for using doses of CSCs >1 million in future clinical trials. Further studies are needed to ascertain whether administration of >1 million hCSCs is associated with greater efficacy in patients with ischemic cardiomyopathy.

Impaired myogenic responses of the Af‐Art contributes to chronic kidney disease in Milan Normotensive rats

We have recently reported that the development of glomerular injury, proteinuria and chronic kidney disease (CKD) in Dahl Salt Sensitive and Fawn Hooded Hypertensive rats are associated with an impaired myogenic response of the afferent arteriole (Af-Art) and autoregulation of renal blood flow (RBF), whereas the myogenic response is enhanced in Spontaneously Hypertensive rats that are resistant to the development of renal disease. Milan normotensive rats (MNS) are more susceptible to development of CKD than the Milan Hypertensive rat (MHS) even though blood pressure is much lower. This study compared the myogenic response in the Af-Art and autoregulation of RBF in 6-9 week old MNS and MHS rats. Autoregulation of RBF was measured following an increase in renal perfusion pressure (RPP) from 100 to 140 mmHg. The diameter of Af-Art of MNS rats increased from 14.0 ± 0.5 to 14.1 ± 0.6 µm (n=6, p>0.05) in response to an increase in perfusion pressure from 60 to 120 mmHg. In contrast, the diameter of the Af-Art decreased significantly from 14.0 ± 0.8 to 11.7 ± 1.1 µm (n=6, p<0.05) in MHS rats. In vivo, MNS rats exhibited poor autoregulation of RBF, it increased by 27% when RPP was increased from 100 to 140 mmHg. In contrast, MHS rats exhibited nearly perfect autoregulation and RBF was not significantly altered. Glomerular capillary pressure estimated from measurement of proximal tubular stop flow pressure increased by 10 mmHg in MNS following the elevation in RPP, but not in MHS rats. These data indicate that impaired myogenic response of the Af-Art contributes to the progression of proteinuria and renal injury in MNS rats. This studies were supported by NIH Grants HL36279 and DK104184-01.

MP43-04 UROFLOW STOP TEST AT TIME OF CATHETER REMOVAL IS A NOVEL AND STRONG PREDICTOR OF EARLY RECOVERY OF ERECTILE FUNCTION FOLLOWING ROBOTIC-ASSISTED RADICAL PROSTATECTOMY (RARP): A PILOT STUDY

You have accessJournal of UrologySexual Function/Dysfunction/Andrology: Evaluation I1 Apr 2015MP43-04 UROFLOW STOP TEST AT TIME OF CATHETER REMOVAL IS A NOVEL AND STRONG PREDICTOR OF EARLY RECOVERY OF ERECTILE FUNCTION FOLLOWING ROBOTIC-ASSISTED RADICAL PROSTATECTOMY (RARP): A PILOT STUDY Abdullah Alenizi, Marc Bienz, Anwar Alesawi, Naif Al-Hathal, Serge Benayoun, Thierry Lebeau, Kevin c Zorn, and Assaad El-Hakim Abdullah AleniziAbdullah Alenizi More articles by this author , Marc BienzMarc Bienz More articles by this author , Anwar AlesawiAnwar Alesawi More articles by this author , Naif Al-HathalNaif Al-Hathal More articles by this author , Serge BenayounSerge Benayoun More articles by this author , Thierry LebeauThierry Lebeau More articles by this author , Kevin c ZornKevin c Zorn More articles by this author , and Assaad El-HakimAssaad El-Hakim More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.1611AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Potency recovery post robot-assisted radical prostatectomy (RARP) remains difficult to predict despite growing knowledge about risk factors. We recently showed that the ability to completely stop urine flow at time of catheter removal (uroflow Stop Test) post RARP is a strong independent predictor of early 3-months urinary continence recovery. The aim of this study is to evaluate whether uroflow Stop Test following RARP, can predict early recovery of potency METHODS In this study, data was collected prospectively on 108 RARP patients operated by a single surgeon (AEH). Prior to catheter removal on postoperative day 7, 150 ml of normal saline was instilled intravesically. Patients were subjected to an uroflowmetry and instructed to stop flow during voiding. Eighty patients had a positive uroflow Stop Test (group one) and 28 had a negative Stop Test (group two). Potency was defined as successful penetration during intercourse and/or erection hardness scale (EHS) score of ≥3/4, with or without PDE5-I. RESULTS Preoperative characteristics were comparable between both groups except nerve sparing and PSA, which were statistically higher in group one (p<0.05). 3- and 6-months potency recovery was significantly higher in group one. Potency rates in group one and two at 1, 3, 6, 9, 12, 18 and 24 months were 25% vs. 14.3% (p0.241), 42.6% vs. 14.8% (p0.010), 54.5% vs. 18.5% (p0.001), 56.4% vs. 36% (p0.084), 66.6% vs. 50% (p0.141), 65.5% vs. 56% (p0.404) and 73.2% vs. 57.7% (p0.160) respectively. Uroflow Stop Test was the strongest independent predictor of early potency recovery on multivariate analysis at 3 and 6 months [OR 6.70 (95%CI: 1.36-32.97, p0.019) and OR 5.46 (95%CI: 1.84-16.20, p0.025), respectively]. CONCLUSIONS Novel use of uroflowmetry at the time of urethral catheter removal is a simple, non-invasive study with strong and independent ability to predict early potency recovery following RARP. Table I. analysis at 3 months Significant predictive variables of potency ODDS RATIO (OR) 95.0% Confidence Interval for OR (lower) 95.0% Confidence Interval for OR (upper) Age 0.869 0.776 0.973 BMI 0.741 0.583 0.942 Uroflow Stop Test 6.698 1.361 32.968 As shown in table I, Uroflow Stop Test was the strongest independent predictor of early potency recovery on multivariate regression analysis at 3 months with an odds ratio (OR) of 6.70 (95%CI: 1.36-32.97, p 0.019).This indicated that respondents who had a positive Stop Test were 6.7 times more likely to report 3-months potency. Similarly, age and BMI were also significant contributors to the model at 3 months with an OR of 0.87 (95%CI: 0.78-0.97, p 0.015) and OR 0.74 (95%CI: 0.58-0.94, p 0.014), respectively. Table II. analysis at 6 months Significant predictive variables of potency ODDS RATIO (OR) 95.0% Confidence Interval for OR (Lower) 95.0% Confidence Interval for OR (upper) BMI 0.799 0.658 0.971 Uroflow Stop Test 5.462 1.842 16.201 At 6 months, uroflow Stop Test was again the strongest predictor of early potency recovery on multivariate regression analysis with an odds ratio (OR) of 5.46 (95%CI: 1.84-16.20, p 0.025). in addition, BMI was also found to be a significant predictor with an OR of 0.80 (95%CI: 0.66-0.97, p 0.024). © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e519 Peer Review Report Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Abdullah Alenizi More articles by this author Marc Bienz More articles by this author Anwar Alesawi More articles by this author Naif Al-Hathal More articles by this author Serge Benayoun More articles by this author Thierry Lebeau More articles by this author Kevin c Zorn More articles by this author Assaad El-Hakim More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Omecamtiv Mecarbil modulates the kinetic and motile properties of porcine β-cardiac myosin.

We determined the effect of Omecamtiv Mecarbil, a novel allosteric effector of cardiac muscle myosin, on the kinetic and "in vitro" motility properties of the porcine ventricular heavy meromyosin (PV-HMM). Omecamtiv Mecarbil increases the equilibrium constant of the hydrolysis step (M-ATP ⇄ M-ADP-Pi) from 2.4 to 6 as determined by quench flow, but the maximal rates of both the hydrolysis step and tryptophan fluorescence increase are unchanged by the drug. OM also increases the amplitude of the fast phase of phosphate dissociation (AM-ADP-Pi → AM-ADP + Pi) that is associated with force production in muscle by 4-fold. These results suggest a mechanism in which hydrolysis of M-ATP to M-ADP-Pi occurs both before and after the recovery stroke, but rapid acceleration of phosphate dissociation by actin occurs only on post-recovery stroke A-M-ADP-Pi. One of the more dramatic effects of OM on PV-HMM is a 14-fold decrease in the unloaded shortening velocity measured by the in vitro motility assay. The increase in flux through phosphate dissociation and the unchanged rate of ADP dissociation (AM-ADP → AM + ADP) by the drug produce a higher duty ratio motor in which a larger fraction of myosin heads are strongly bound to actin filaments. The increased internal load produced by a larger fraction of strongly attached crossbridges explains the reduced rate of in vitro motility velocity in the presence of OM and predicts that the drug will produce slower and stronger contraction of cardiac muscle.

We Built This House; It's Time to Move in: Leveraging Existing DICOM Structure to More Completely Utilize Readily Available Detailed Contrast Administration Information.

The Digital Imaging and Communications in Medicine (DICOM) standard is the universal format for interoperability in medical imaging. In addition to imaging data, DICOM has evolved to support a wide range of imaging metadata including contrast administration data that is readily available from many modern contrast injectors. Contrast agent, route of administration, start and stop time, volume, flow rate, and duration can be recorded using DICOM attributes [1]. While this information is sparsely and inconsistently recorded in routine clinical practice, it could potentially be of significant diagnostic value. This work will describe parameters recorded by automatic contrast injectors, summarize the DICOM mechanisms available for tracking contrast injection data, and discuss the role of such data in clinical radiology.

Fusidic Acid Targets Elongation Factor G in Several Stages of Translocation on the Bacterial Ribosome

The antibiotic fusidic acid (FA) targets elongation factor G (EF-G) and inhibits ribosomal peptide elongation and ribosome recycling, but deeper mechanistic aspects of FA action have remained unknown. Using quench flow and stopped flow experiments in a biochemical system for protein synthesis and taking advantage of separate time scales for inhibited (10 s) and uninhibited (100 ms) elongation cycles, a detailed kinetic model of FA action was obtained. FA targets EF-G at an early stage in the translocation process (I), which proceeds unhindered by the presence of the drug to a later stage (II), where the ribosome stalls. Stalling may also occur at a third stage of translocation (III), just before release of EF-G from the post-translocation ribosome. We show that FA is a strong elongation inhibitor (K50% ≈ 1 μm), discuss the identity of the FA targeted states, and place existing cryo-EM and crystal structures in their functional context.

Intra-arterial, abdominal chemoperfusion with chemofiltration in the treatment of progressive stage IV gastric cancer.

141 Background: Treatment of patients (pts.) with progeressive stage IV gastric cancer remains a therapeutical problem. Survival of the pretreated pts. is low and the therapeutic options are sparse. In this situation, locoregional therapeutic strategies could be an option. Methods: 28 pretreated pts. (17 male, 11 female, mean age 59 y.) after resection and at least second line systemic chemotherapy were included in a phase II study of isolated abdominal perfusion and subsequent chemofiltration. All pts. had liver metastases (mets.), 50% (n = 14) had peritoneal carcinomatosis with malignant ascites. No pat. had cerebral, pulmonal or bone mets.. After insertion of a venous and arterial 21 ch. stop flow catheter via a femoral access, the v. cava was blocked beneath the right atrium, the arterial catheter was blocked above the celiac trunk. The thighs were blocked by pneumatic cuffs. Chemotherapy consisted of 35 mg/m2 cisplatinum, 20 mg/m2 adriamycin and 12 mg/m2 mitomycin q 3 weeks till progress or dead. The agents were administered via the arterial access, followed by 15 min of hypoxic abdominal perfusion via an external pump, followed by chemofiltration for 45 min. The procedure was done under general anaesthesia. Primary endpoint of the study were overall survival, secondary endpoint was control of the ascites. Results: A total of 92 cycles (mean 3.25) were administered. Toxicity was low with leucopenia CTC grad I in 9 pts., gastrointestinal disorders grad II in 8 pts. and surgical complications grad II in 40 % of the pat. (lymphatic fistula). In 9/14 (65%) of pts. with ascites, the ascites was at least controlled or vanished. One year survival was 28.6% (Kaplan-Meier), 2 year survival was 11.4%. Median survival was 6 months. Conclusions: Intra-arterial, isolated abdominal chemoperfusion with consecutive chemofiltration in heavily pretreated patients with gastric cancer metastasized to the abdominal cavity is a valuable option for palliative treatment with low side effects. In 65% of the affected pts., malignant ascites was controlled sufficiently, ameliorating the quality of life.

Reduced adenosine A2a receptor–mediated efferent arteriolar vasodilation contributes to diabetes-induced glomerular hyperfiltration

Diabetes is associated with increased risk for development of kidney disease, and an increased glomerular filtration rate is an early indication of altered kidney function. Here we determine whether reduced adenosine A2a receptor-mediated vasodilation of the efferent arteriole contributes to the increased glomerular filtration rate in diabetes. The glomerular filtration rate, renal blood flow, and proximal tubular stop flow pressure were investigated in control and streptozotocin-diabetic rats during baseline and after administration of the adenosine A2a receptor antagonist ZM241385 or the adenosine A2a receptor agonist CGS21680. The diabetes-induced glomerular hyperfiltration was reduced by 24% following A2a receptor stimulation but was unaffected by A2a receptor inhibition. Contrarily, glomerular filtration rate in controls increased by 22% after A2a receptor inhibition and was unaffected by A2a stimulation. The increased glomerular filtration rate after A2a receptor inhibition in controls and decreased glomerular filtration rate after A2a receptor activation in diabetics were caused by increased and decreased stop flow pressure, respectively. None of the interventions affected renal blood flow. Thus, the normal adenosine A2a receptor-mediated tonic vasodilation of efferent arterioles is abolished in the diabetic kidney. This causes increased efferent arteriolar resistance resulting in increased filtration fraction and hyperfiltration.