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Selected AbstractsHuman enamel dissolution in citric acid as a function of pH in the range 2.30,pH,6.30 , a nanoindentation studyEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2003Michele E. Barbour The objective of this study was to investigate the dissolution of human enamel in citric acid solutions over a wide range of pH. The in vitro conditions are considered to be relevant to soft drink-induced enamel erosion. Nanoindentation was used to investigate changes in the nanomechanical properties of polished enamel surfaces after exposure to citric acid solutions. Solutions used had 38.1 mmol l,1 citric acid and pH greater than 2.3 but less than 6.3 (2.30 pH 6.30). Samples were exposed to rapidly stirred, constant composition solutions for 120 s. Statistically significant changes in enamel hardness and reduced elastic modulus were observed after exposure to all solutions. There was an approximately linear dependence of enamel hardness on solution pH for 2.90 pH 6.30. Below pH 2.90, enamel is thought to have reached the lowest possible hardness value. The reduction in enamel dissolution caused by an increase in pH of a soft drink is likely to be small. Product modification to reduce the erosive potential of drinks may require additional methods such as addition of calcium salts. [source] Effect of root surface treatment with propolis and fluoride in delayed tooth replantation in ratsDENTAL TRAUMATOLOGY, Issue 6 2008Jéssica Lemos Gulinelli Nevertheless, an extended extraoral period damages the periodontal ligament and results in external root resorption. The purpose of this study was to assess by histologic and histometric analysis, the influence of propolis 15% (natural resinous substance collected by Apis mellifera bees from various plants) and the fluoride solution used as root surface treatment on the healing process after delayed tooth replantation. Thirty Wistar (Rattus norvegicus albinus) rats were submitted to extraction of their upper right incisor. The teeth were maintained in a dry environment for 60 min. After this, the pulp was extirpated and the papilla, enamel organ and periodontal ligament were removed with scalpel. The teeth were divided into three experimental groups: Group I , teeth immersed in 20 ml of physiologic saline; Group II , teeth immersed in 20 ml of 2% acidulated phosphate sodium fluoride; Group III , teeth immersed in 20 ml of 15% propolis. After 10 min of immersion in the solutions, the root canals were dried and filled with calcium hydroxide paste and the teeth were replanted. The animals were euthanized 60 days after replantation. The results showed that similar external root resorption was seen in the propolis and fluoride groups. Teeth treated with physiologic saline tended to have more inflammatory root resorption compared with those treated with fluoride or propolis. However, the comparative analysis did not reveal statistically significant differences (P > 0.05) between the treatment modalities when used for delayed tooth replantation. [source] Flux enhancement in TFC RO membranesENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2001Mark A. Kuehne The effects of varying processing conditions during fabrication of TFC RO membranes were systematically investigated. It was found that the membrane flux is greatly dependent on the processing steps that follow the synthesis of the thin film coating, such as washing, treatment with glycerol, and drying of the membrane. Glycerol is not simply a passive flux - p reserving agent, preventing loss of porosity during oven drying. In combination with a second oven drying step, glycerol actively enhances flux. Membrane flux can be similarly enhanced by treatment with solutions of organic salts, followed by oven drying. The effect of these treatments is quite large, increasing the flux by 30,70%, with no loss of salt rejection. Flux-enhancing additives were also used in the aqueous polyamine solution used to prepare the thin film coating. [source] Facile and Reproducible Synthesis of Nanostructured Colloidal ZnO Nanoparticles from Zinc Acetylacetonate: Effect of Experimental Parameters and Mechanistic InvestigationsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 33 2009Alessia Famengo Abstract A facile and reproducible route to nanostructured colloidal ZnO nanoparticles was developed by controlled hydrolysis and condensation of zinc acetylacetonate in alkaline conditions. By reaction of an ethanolic solution of Zn(acac)2 with NaOH in a 1:2 molar ratio, after reflux, ZnO spherical nanoparticles were obtained that displayed a homogeneous size distribution; particle diameters ranged from 6 to 10 nm, as evidenced by transmission electron microscopy (TEM) analysis. The same reaction was carried out also in water, glycerol and 1,2-propanediol, to investigate the effect of the solvent viscosity and dielectric constant on the final features of the obtained material. Irrespective of the nature of the solvent, X-ray diffraction (XRD) analysis shows the formation ofhexagonal ZnO, whereas the presence of residual unreacted Zn(acac)2 could be ruled out. Indeed, different particle sizes and very different morphologies were obtained. Also the reflux step was shown to be a key factor in avoiding the fast precipitation of a floc and achieving a pure compound, which was isolated and thoroughly characterised. The composition of the obtained ZnO was determined by elemental analysis, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA), showing the formation of pure ZnO. IR spectroscopy evidenced the presence of adsorbed organic ligands on the colloid surfaces. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) revealed the presence of medium- to high-strength acidic sites on the ZnO surface. To gain a deeper insight into the formation mechanisms of these nanostructures, time-resolved UV/Vis and XAS studies were performed on the ethanol solution used for the synthesis of the oxide and also on the solid specimen, obtained after the refluxing step. No remarkable changes could be evidenced in the solution after the addition of an understoichiometric amount of NaOH, but the growth of the ZnO nanoparticles could be followed by UV/Vis spectra. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Experimental study and analysis of the application of ice-storage capsules in an air conditioning systemHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 1 2002Shuiquan Ye Abstract Ice-storage capsules are used in an energy-efficient air conditioning system. Experiments and numerical simulations were conducted to investigate the effects of different structural configurations of the capsules on the freezing and melting processes of the refrigerant solution sealed inside the capsules. The predictions of the numerical simulation are in good agreement with the test results. The results show that the freezing speed of the capsules equipped with a metal core is 30% to 50% faster than for capsules without the metal core. In addition, it was found that the special refrigerant solution used in the experiment had a lower freezing point and a higher freezing speed than water. The effects of the size of the metal core, and the coolant temperatures are also investigated. © 2001 Scripta Technica, Heat Trans Asian Res, 31(1): 21,27, 2002 [source] Percutaneous drainage of hydatid cyst of the liver: long-term resultsHPB, Issue 4 2002KY Polat Background Previously surgical operation was the only accepted treatment for hydatid liver cysts. Recently percutaneous management has become more preferable because of its low morbidity rate and lower cost. Patients and methods In all, 101 patients harbouring 120 hydatid cysts of the liver were treated by percutaneous drainage between October 1994 and December 1997. Of these cysts, 89 were in the right liver and 31 in the left liver. Thirty-one patients had had previous operations for hydatid disease. All cysts had an anechoic or hypoechoic unilocular appearance on ultrasound scan. The mean dimension of the cysts was 7.5 ± 2.9 cm (range 3,10.4 cm). All patients received oral albendazole 10 mg/kg perioperatively. After aspiration under sonographic guidance, cysts were irrigated with 95% ethanol. Results The amount of cyst fluid aspirated was 220 ± 75 ml and the amount of irrigation solution used was 175 ± 42 ml. Four patients developed mild fever and three had urticaria. Mean length of hospital stay was 2.1 ± 0.7 (range 1,4) days, and patients were followed up for 43,62 months (mean 54 ± 5.4 months). Maximal cyst diameter decreased from 7.5 ± 2.9 cm to 3.2 ± 15 cm (p<0.001). Sonographic examinations revealed high-level heterogeneous echoes in the cyst cavity (heterogeneous echo pattern), while the cyst cavity was completely obliterated by echogenic material (pseudotumour echo pattern). Discussion Most hydatid cysts of the liver can be managed successfully by acombinationof drugtherapyand percutaneous drainage. [source] Recovery of Enterococcus faecalis after single- or multiple-visit root canal treatments carried out in infected teeth ex vivoINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2005N. Vivacqua-Gomes Abstract Aim, To assess the presence of Enterococcus faecalis after root canal treatment in single or multiple visits in an ex vivo model. Methodology, Forty-five premolar teeth were infected ex vivo with E. faecalis for 60 days. The canals were then prepared using a crowndown technique with System GT and Gates,Glidden burs and irrigated with 2% chlorhexidine gel. The specimens were divided into five groups (G1, G2, G3, G4 and G5) according to the time elapsed between chemical,mechanical preparation and root canal filling, the irrigant solution used and the use or nonuse of a calcium hydroxide intra-canal medicament. The teeth were then root-filled and incubated for 60 days at 37 °C. Dentine chips were removed from the canal walls with sequential sterile round burs at low speed. The samples obtained with each bur were immediately collected in separate test tubes containing Brain,Heart Infusion broth. These samples were placed onto agar plates and colony forming units were counted after 24 h at 37 °C. Data were ranked and analysed using the Kruskal,Wallis statistical test. Results,Enterococcus faecalis was recovered from 20% (three of 15 specimens) of G1 (chlorhexidine irrigation and immediate root filling in a single visit), 25% (four of 15 specimens) of G2 (chlorhexidine irrigation and filling after 14 days use of a calcium hydroxide dressing in multiple visits), 40% (two of five specimens) of G3 (chlorhexidine irrigation and filling after 7 days), 60% (three of five specimens) of G4 (saline irrigation and filling after 7 days) and from 100% (five of five specimens) of G5 (saline irrigation and immediate filling without sealer). Conclusions, Neither single- nor multiple-visit root canal treatment ex vivo, eliminated E. faecalis completely from dentinal tubules. Up to 60 days after root filling, E. faecalis remained viable inside dentinal tubules. When no sealer was used, E. faecalis presented a higher growth rate. [source] On the stability and convergence of a Galerkin reduced order model (ROM) of compressible flow with solid wall and far-field boundary treatment,INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 10 2010I. Kalashnikova Abstract A reduced order model (ROM) based on the proper orthogonal decomposition (POD)/Galerkin projection method is proposed as an alternative discretization of the linearized compressible Euler equations. It is shown that the numerical stability of the ROM is intimately tied to the choice of inner product used to define the Galerkin projection. For the linearized compressible Euler equations, a symmetry transformation motivates the construction of a weighted L2 inner product that guarantees certain stability bounds satisfied by the ROM. Sufficient conditions for well-posedness and stability of the present Galerkin projection method applied to a general linear hyperbolic initial boundary value problem (IBVP) are stated and proven. Well-posed and stable far-field and solid wall boundary conditions are formulated for the linearized compressible Euler ROM using these more general results. A convergence analysis employing a stable penalty-like formulation of the boundary conditions reveals that the ROM solution converges to the exact solution with refinement of both the numerical solution used to generate the ROM and of the POD basis. An a priori error estimate for the computed ROM solution is derived, and examined using a numerical test case. Published in 2010 by John Wiley & Sons, Ltd. [source] Behaviour of polysorbate 20 during dialysis, concentration and filtration using membrane separation techniquesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2008Hanns-Christian Mahler Abstract During formulation development of a therapeutic protein, combinations of buffers, pH and excipients need to be tested. As the protein bulk solution used for formulation development usually contains a buffer component at a defined pH and potentially one or more excipients already, this bulk requires to be processed. In case low concentrations of non-ionic surfactants, for example polysorbate 20, are already present in the bulk, the surfactant needs to be removed in lab-scale for further development use. The scope of the work was to study the behaviour of low concentrations of polysorbate 20 during membrane separation processes. The first part focuses on evaluating the behaviour of polysorbate 20 during a dialysis process, whereas the second part analyses concentration changes of polysorbate during a membrane concentration process using a stirred cell. The third part analyses potential membrane absorption of polysorbate at sterilizing-grade filters. In conclusion, it was found that polysorbate could not be significantly reduced during a dialysis process and accumulated during a membrane concentration process in unreproducable manner. During sterile filtration, no significant influence on the concentration of polysorbate was measurable. In any case, it is recommendable to quantify the concentration of polysorbate during critical membrane process steps in pharmaceutical industry. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:764,774, 2008 [source] Preservation of mouse liver tissue during cold storage in experimental solutions assessed by x-ray microanalysisLIVER TRANSPLANTATION, Issue 3 2003Inna Kozlova The increasing use of organs for transplantation necessitates the development of optimal preservation techniques. The goal of this study was to investigate changes in elemental content in mouse liver cells during cold storage by x-ray microanalysis in parallel with morphologic studies. Tissue was stored at 4°C for 4 to 12 hours in normal Krebs-Ringer solution (high sodium/potassium ratio), modified Krebs-Ringer solution (low Na+/K+ ratio), Euro-Collins solution, University of Wisconsin (UW) solution, or seven modified versions of the UW solution. Incubation of liver in normal Krebs-Ringer solution caused a significant increase in sodium and decrease in potassium concentrations in contrast to incubation in other solutions. The concentration of sodium, potassium, and chlorine in the cells closely followed the concentration in the storage solution, indicating that the intracellular concentration of these ions during storage is entirely dependent on diffusion processes. The calcium concentration was independent of the storage solution used. Studies by light and transmission electron microscopy showed good preservation of hepatocytes after storage for 8 and 12 hours in UW solution and its variants, modified Krebs-Ringer solution and Euro-Collins solution, but showed moderate damage to mitochondria and swelling of the endoplasmic reticulum in normal Krebs-Ringer solution. In addition, damage to the sinusoidal endothelial cells was observed after 4 hours in normal Krebs-Ringer solution and after 8 to 12 hours in the other solutions. In conclusion, the only factor determining the intracellular concentration of diffusible ions after cold tissue storage is the ionic composition of the extracellular medium. X-ray microanalysis provides an objective method for assessing whether the intracellular ionic composition of tissue is maintained during storage. [source] Immobilization of Candida antarctica lipase B on Polystyrene NanoparticlesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 1 2010Nemanja Mileti Abstract Polystyrene (PS) nanoparticles were prepared via a nanoprecipitation process. The influence of the pH of the buffer solution used during the immobilization process on the loading of Candida antarctica lipase B (Cal-B) and on the hydrolytic activity (hydrolysis of p -nitrophenyl acetate) of the immobilized Cal-B was studied. The pH of the buffer solution has no influence on enzyme loading, while immobilized enzyme activity is very dependent on the pH of adsorption. Cal-B immobilized on PS nanoparticles in buffer solution pH 6.8 performed higher hydrolytic activity than crude enzyme powder and Novozyme 435. [source] Selective imaging of positively charged polar and nonpolar lipids by optimizing matrix solution compositionRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2009Yuki Sugiura Previous studies have shown that matrix-assisted laser desorption/ionization,imaging mass spectrometry (MALDI-IMS) is useful for studying the distribution of various small metabolites, particularly lipids. However, in this technique, selective ionization of the target molecules is imperative, particularly when analyzing small molecules. Since the sample clean-up procedures available for the MALDI-IMS of small metabolites are limited, the tissue sample will contain numerous molecular species other than the target molecules. These molecules will compete for ionization resulting in severe ion suppression. Hence, it is necessary to develop and optimize a sample preparation protocol for the target molecules. In this study, through model experiments using reference compounds, we optimized the composition of the matrix solution used for positively charged lipids in terms of the concentration of the organic solvent and presence/absence of alkali metal salts. We demonstrated that a high concentration of organic solvent in the matrix solution favors the preferential detection of lipids over peptides. The presence of alkali metal salts in the matrix solution was favorable for the detection of polar lipids, while a salt-free matrix solution was suitable for the detection of nonpolar lipids. Furthermore, potassium salts added to the matrix solution caused merging of various lipid adducts (adducts with proton, sodium, and potassium) into one single potassiated species. Using the optimized protocols, we selectively analyzed phosphatidylcholine (PC) and triacylglycerol (TG) with different fatty acid compositions in a rat kidney section. Copyright © 2009 John Wiley & Sons, Ltd. [source] Approximation method for high-degree harmonics in normal mode modellingGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2002R. E. M. Riva Summary For some loading applications, the normal modes approach to the viscoelastic relaxation of a spherical earth requires the use of spherical harmonics up to a high degree. Examples include postseismic deformation (internal loading) and sea level variations due to glacial isostatic adjustment (external loading). In the case of postseismic modelling, the convergence of the solution, given as a spherical harmonic expansion series, is directly dependent on loading depth and requires several thousands of terms for shallow earthquake sources. The particular structure of the analytical fundamental solutions used in normal mode techniques usually does not allow a straightforward calculation, since numerical problems can readily occur due to the stiffness of the matrices used in the propagation routines. Here we show a way of removing this stiffness problem by approximating the fundamental matrix solutions, followed by a rescaling procedure, in this way we can virtually go up to whatever harmonic degree is required. [source] Targeted delivery of salicylic acid from acne treatment products into and through skin: role of solution and ingredient properties and relationships to irritationINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2004L. Rhein Salicylic acid (SA) is a beta-hydroxy acid and has multifunctional uses in the treatment of various diseases in skin such as acne, psoriasis, and photoaging. One problem often cited as associated with salicylic acid is that it can be quite irritating at pH 3,4, where it exhibits the highest activity in the treatment of skin diseases. We have identified strategies to control the irritation potential of salicylic acid formulations and have focused on hydroalcoholic solutions used in acne wipes. One strategy is to control the penetration of SA into the skin. Penetration of the drug into various layers of skin, i.e. epidermis, dermis, and receptor fluid, was measured using a modified Franz in vitro diffusion method after various exposure times up to 24 h. A polyurethane polymer (polyolprepolymer-15) was found to be an effective agent in controlling delivery of SA. In a dose-dependent fashion it targeted delivery of more SA to the epidermis as compared to penetration through the skin into the receptor fluid. It also reduced the rapid rate of permeation of a large dose of SA through the skin in the first few hours of exposure. A second strategy that proved successful was incorporation of known mild nonionic surfactants like isoceteth-20. These surfactants cleanse the skin, yet due to their inherent mildness (because of their reduced critical micelle concentration and monomer concentration), keep the barrier intact. Also, they reduce the rate of salicylic acid penetration, presumably through micellar entrapment (either in solution or on the skin surface after the alcohol evaporates). Cumulative irritation studies showed that targeting delivery of SA to the epidermis and reducing the rapid early rate of penetration of large amounts of drug through the skin resulted in a reduced irritation potential. In vivo irritation studies also showed that the surfactant system is the most important factor controlling irritancy. SA delivery is secondary, as formulations with less SA content reduced the rate of delivery to the receptor and yet were some of the most irritating formulations tested, presumably due to the action of the specific anionic surfactant on the barrier. Alcohol content also did not appreciably affect irritation and SA delivery; formulations with considerably low alcohol content but containing anionic versus nonionic surfactant systems exhibited considerably higher irritancy. Thus the surfactant type was again the predominant factor in those studies, although arguably alcohol plays some role (solubilization of SA). Results showed that both polymers and mild surfactants work in concert to provide the optimal formulation benefits of targeted delivery and reduced irritation. Synergistic relationships among hydroalcoholic formulation components will be discussed along with the mechanisms likely involved in controlling delivery of SA to skin. [source] Fluid regimens for colostomy irrigation: a systematic reviewINTERNATIONAL JOURNAL OF EVIDENCE BASED HEALTHCARE, Issue 3 2008Lucylynn Lizarondo Abstract Background, Various techniques for managing faecal evacuation have been proposed; however, colostomy irrigation is favoured as it leads to better patient outcomes. Alternative fluid regimens for colostomy irrigation have been suggested to achieve effective evacuation. Aim, The objective of this review was to summarise the best available evidence on the most effective fluid regimen for colostomy irrigation. Search strategy, Trials were identified by electronic searches of CINAHL, PubMed, MEDLINE, Current Contents, the Cochrane Library and EMBASE. Unpublished articles and references lists from included studies were also searched. Selection criteria, Randomised controlled trials and before-and-after studies investigating any fluid regimen for colostomy irrigation were eligible for inclusion. Outcomes measured included fluid inflow time, total wash-out time, haemodynamic changes during irrigation, cramps, leakage episodes, quality of life and level of satisfaction. Data collection and analysis, Trial selection, quality appraisal and data extraction were carried out independently by two reviewers. Differences in opinion were resolved by discussion. Main results, The systematic literature search strategy identified two cross-over trials that compared water with another fluid regimen. Owing to the differences in irrigating solutions used, the results were not pooled for analysis. Both the polyethylene glycol electrolyte solution and glyceryl trinitrate performed significantly better than water. Conclusion, There is some evidence to support the effectiveness of fluid regimens other than water, such as polyethylene glycol electrolyte and glyceryl trinitrate, for colostomy irrigation. Further well-designed clinical trials are required to establish solid evidence on the effectiveness of other irrigating solutions that might enhance colonic irrigation. [source] A case of fatal caffeine poisoningACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2010T. RUDOLPH Caffeine is a natural alkaloid methylxanthine that is found in various plants such as coffee or tea. Symptoms of a severe overdose may present with hypokalemia, hyponatremia, ventricular arrhythmias, hypertension followed by hypotension, respiratory failure, seizures, rhabdomyolysis, ventricular fibrillation and finally circulatory collapse. A 21-year-old woman called for the ambulance herself soon after the ingestion of about 10,000 mg of caffeine. At the arrival of the ambulance, the patient went into cardiac arrest almost immediately. After a total resuscitation period of 34 min including seven counter-shocks and 2 mg epinephrine, the patient was stable enough to be transferred to the hospital. The patient soon went into VF again and received two more counter-shocks and 1 mg epinephrine and finally an intravenous bolus dose of 300 mg amiodarone. The initial arterial blood gas showed pH at 6.47, lactate at 33 mmol/l and potassium level at 2.3 mmol/l. Unfortunately, no blood samples for caffeine analysis were taken. Three days after hospital admission, the patient developed myoclonus, which did not respond to medical treatment. Excessive intake of caffeine may produce arrhythmias and pronounced hypokalemia and ensuing ventricular fibrillation. In case of counter-shock-resistant VF, it can be necessary to give an early loading dose of amiodarone. Furthermore, it may be beneficial to replace the potassium as early as possible. Epinephrine and buffer solutions used during resuscitation may further decrease blood potassium levels and should be administrated cautiously. Epinephrine can be replaced by other vasopressor drugs, such as vasopressin without effects on ,-receptors. [source] Synthesis of poly(N,N -diethylacrylamide- co -acrylic acid) hydrogels with fast response rate in NaCl mediumJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Hongliang Liu Abstract A series of thermo- and pH-sensitive poly (N,N -diethylacrylamide- co -acrylic acid) (P(DEA- co -AA)) hydrogels were prepared in NaCl aqueous solutions with different concentrations. Swelling and deswelling studies showed that in comparison with conventional P(DEA- co -AA) hydrogels (prepared in distilled water), the P(DEA- co -AA) hydrogels thus prepared had almost the same volume phase transition temperature (VPTT), but exhibited much faster response rates as the temperature was raised above their VPTT. Besides, the hydrogels prepared by this method had faster response rates in low pH buffer solutions, and the response rates increased with the increased concentration of the NaCl solutions used during the polymerization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] The BCH Epidural System, a safe system for epidural infusion analgesia in childrenPEDIATRIC ANESTHESIA, Issue 9 2002N. Llewellyn Epidural infusions in children are usually delivered by syringe drivers because of the lower volumes of local anaesthetic solutions used in children rather than in adult practice. Recently concern has arisen both via the media and anecdotally over a number of adverse events associated with intravenous administration of bupivacaine. We have designed and validated a system that should significantly reduce the possibility and incidence of this adverse effect. (1) [ The system is based on the reversal of the standard luer-lock system. ] A female 60 cc syringe is connected to a reversed 150 cm infusion line that is connected to a male epidural filter. The filter connects with standard epidural infusion catheters. The reversal of the luer-lock system requires that devices are also available for the initial doses of local anaesthetic, for the preparation of the epidural infusion syringe and for administration of rescue boluses of local anaesthetic. With this system it is extremely unlikely that the epidural syringe or infusion catheter can be connected to an intravenous line. It is also less likely that intravenous drugs may be connected to the epidural filter. [source] Standardized procedure for measurement of nasal potential difference: An outcome measure in multicenter cystic fibrosis clinical trials,PEDIATRIC PULMONOLOGY, Issue 5 2004Thomas A. Standaert PhD Abstract Patients with cystic fibrosis (CF) can be discriminated from healthy subjects by measurement of the nasal potential difference, which has become a useful outcome measure for therapies directed toward correcting defective electrolyte transport in CF. A standard operating procedure was developed by a CF Foundation clinical trials network, to be followed by all sites performing collaborative studies. Key variables in the measurement included type of voltmeter, exploring probe, reference electrodes, and solutions used to assess both sodium transport and chloride conductance. Eight sites submitted data on 3,8 normal and 4,5 CF subjects. Baseline voltage, an index of sodium transport, was ,18.2,±,8.3 mV (mean,±,SD) for normals, and ,45.3,±,11.4 mV for CF patients. There was no CFTR-mediated chloride secretion in CF subjects, as evidenced by the lack of response to perfusion with zero chloride,+,beta agonist solutions (+3.2,±,3.5 mV) vs. that in normals (,23.7,±,10.2 mV). The standardized nasal potential difference measurement minimizes variability between operators and study sites. Valid and consistent results can be attained with trained operators and attention to technical details. These data demonstrate the procedure to be sufficient for multicenter studies in the CF Foundation network. Pediatr Pulmonol. 2004; 37:385,392. © 2004 Wiely-Liss, Inc. [source] Compatibility of detergents with the microbatch-under-oil crystallization methodACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2003Patrick J. Loll Detergents are required to solubilize integral membrane proteins and are common components of the solutions used to crystallize these molecules. It has been unclear whether these detergents are completely compatible with the oils used in the microbatch-under-oil crystallization technique, because they might conceivably be lost from solution by partitioning into the oil phase. The partitioning of the detergents n -octyl-,- d -glucopyranoside and Fos-Choline-12 into two different oils used for microbatch crystallization experiments has been examined. It was found that vigorous mixing and prolonged incubation of the aqueous detergent solutions with the oils leads to small losses of detergent (approximately 5% of the total detergent mass); however, gentle mixing that is more typical of the mixing encountered in a crystallization experiments leads to negligible loss of detergent. [source] Amphiphiles modify the properties of detergent solutions used in crystallization of membrane proteinsACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2001M. A. Rosenow The effect of the amphiphile heptanetriol on the properties of solutions containing several detergents commonly used for crystallization of membrane proteins was characterized. The critical micelle concentration was found to be relatively unchanged by the presence of the amphiphile. In contrast, the addition of heptanetriol to solutions containing both detergent and polyethylene glycol exhibited significant shifts in the clouding behavior, with the largest shifts being for lauryl dimethylamine oxide. These results suggest that conditions favorable for crystallization of integral membrane proteins can be inferred from the properties of the detergents and amphiphiles. [source] | |||||||||||||||||||