Variable speed refrigeration system with HPF input rectifier stage

This paper is based on the analysis and implementation of a new drive system applied to refrigeration systems, complying with the restrictions imposed by the IEC standards (Harmonic/Flicker/EMI-Electromagnetic Interference restrictions), in order to obtain high efficiency, high power factor, reduced harmonic distortion in the input current and reduced electromagnetic interference, with excellent performance in temperature control of a refrigeration prototype system (automatic control, precision and high dynamic response). The proposal is replace the single-phase motor by a three-phase motor, in the conventional refrigeration system. In this way, a proper control technique can be applied, using a closed-loop (feedback control), that will allow an accurate adjustment of the desirable temperature. The proposed refrigeration prototype uses a 0.5Hp three-phase motor and an open (Belt-Drive) Bitzer IY type compressor. The input rectifier stage's features include the reduction in the input current ripple, the reduction in the output voltage ripple, the use of low stress devices, low volume for the EMI input filter, high input power factor (PF), and low total harmonic distortion (THD) in the input current, in compliance with the IEC61000-3-2 standards. The digital controller for the output three-phase inverter stage has been developed using a conventional voltage-frequency control (scalar V/f control), and a simplified stator oriented Vector control, in order to verify the feasibility and performance of the proposed digital controls for continuous temperature control applied at the refrigerator prototype. ©2008 IEEE.

Acute phase protein profile in agoutis (Dasyprocta azarae; Lichtenstein, 1823) in captivity, determined by sodium dodecyl sulfate polyacrilamyde gel electrophoresis

The acute phase response refers to a nonspecific and complex systemic reaction of the organism that occurs shortly after any tissue injury. The acute phase response is considered a part of the innate host defense system, which is responsible for the survival of the host during the critical early stages of attack, and in evolutionary terms, it precedes the acquired immune response. The purpose of this study was to determine serum protein concentrations, including the acute phase protein profile in agoutis (Dasyprocta azarae) in captivity, by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis. Blood samples from 11 adult healthy animals (nine females and two males) were obtained. The serum proteinogram had 21 proteins with molecular weights ranging from 15 to 240 kD. The acute phase proteins identified were: ceruloplasmin, transferrin, albumin, haptoglobin, α-1-acid glycoprotein, and hemoglobin. IgA, IgG heavy and light chains, and nonnominal identified proteins of 240, 210, 140, 98, 78, 48, 35, 31, 23, and 15 kD were also identified. The determination of the acute phase protein concentrations is a useful method for the early detection of subclinical disease or changes in the healthy animal, with predictive information on the development of disease in the future. It is possible to standardize the reference values of the serum protein profile of agoutis, which can be used for diagnosis and prognosis, treatment and clinical follow-up of nutritional disorders, and immune-mediated inflammatory diseases that may affect these animals. © 2012 Springer-Verlag London Limited.

A novel HS-SBSE system coupled with gas chromatography and mass spectrometry for the analysis of organochlorine pesticides in water samples

A methodology to analyze organochlorine pesticides (OCPs) in water samples has been accomplished by using headspace stir bar sorptive extraction (HS-SBSE). The bars were in house coated with a thick film of PDMS in order to properly work in the headspace mode. Sampling was done by a novel HS-SBSE system whereas the analysis was performed by capillary GC coupled mass spectrometric detection (HS-SBSE-GC-MS). The extraction optimization, using different experimental parameters has been established by a standard equilibrium time of 120 min at 85 degrees C. A mixture of ACN/toluene as back extraction solvent promoted a good performance to remove the OCPs sorbed in the bar. Reproducibility between 2.1 and 14.8% and linearity between 0.96 and 1.0 were obtained for pesticides spiked in a linear range between 5 and 17 ng/g in water samples during the bar evaluation.

Glucose Control in Acute Myocardial Infarction: A Pilot Randomized Study Controlled by Continuous Glucose Monitoring System Comparing the Use of Insulin Glargine with Standard of Care

Background: This pilot study aimed to verify if glycemic control can be achieved in type 2 diabetes patients after acute myocardial infarction (AMI), using insulin glargine (iGlar) associated with regular insulin (iReg), compared with the standard intensive care unit protocol, which uses continuous insulin intravenous delivery followed by NPH insulin and iReg (St. Care). Patients and Methods: Patients (n = 20) within 24 h of AMI were randomized to iGlar or St. Care. Therapy was guided exclusively by capillary blood glucose (CBG), but glucometric parameters were also analyzed by blinded continuous glucose monitoring system (CGMS). Results: Mean glycemia was 141 +/- 39 mg/dL for St. Care and 132 +/- 42 mg/dL for iGlar by CBG or 138 +/- 35 mg/dL for St. Care and 129 +/- 34 mg/dL for iGlar by CGMS. Percentage of time in range (80-180 mg/dL) by CGMS was 73 +/- 18% for iGlar and 77 +/- 11% for St. Care. No severe hypoglycemia (<= 40 mg/dL) was detected by CBG, but CGMS indicated 11 (St. Care) and seven (iGlar) excursions in four subjects from each group, mostly in sulfonylurea users (six of eight patients). Conclusions: This pilot study suggests that equivalent glycemic control without increase in severe hyperglycemia may be achieved using iGlar with background iReg. Data outputs were controlled by both CBG and CGMS measurements in a real-life setting to ensure reliability. Based on CGMS measurements, there were significant numbers of glycemic excursions outside of the target range. However, this was not detected by CBG. In addition, the data indicate that previous use of sulfonylurea may be a potential major risk factor for severe hypoglycemia irrespective of the type of insulin treatment.

Capillary bioreactors based on human purine nucleoside phosphorylase: A new approach for ligands identification and characterization

The enzyme purine nucleoside phosphorylase (PNP) is a target for the discovery of new lead compounds employed on the treatment severe T-cell mediated disorders. Within this context, the development of new, direct, and reliable methods for ligands screening is an important task. This paper describes the preparation of fused silica capillaries human PNP (HsPNP) immobilized enzyme reactor (IMER). The activity of the obtained IMER is monitored on line in a multidimensional liquid chromatography system, by the quantification of the product formed throughout the enzymatic reaction. The Km value for the immobilized enzyme was about twofold higher than that measured for the enzyme in solution (255 +/- 29.2 mu M and 133 +/- 114.9 mu M, respectively). A new fourth-generation immucillin derivative (DI4G: IC50 = 40.6 +/- 0.36 nM), previously identified and characterized in HsPNP free enzyme assays, was used to validate the IMER as a screening method for HsPNP ligands. The validated method was also used for mechanistic studies with this inhibitor. This new approach is a valuable tool to PNP ligand screening, since it directly measures the hypoxanthine released by inosine phosphorolysis, thus furnishing more reliable results than those one used in a coupled enzymatic spectrophotometric assay. (C) 2011 Elsevier B.V. All rights reserved.

Identification of 2 Novel ANTXR2 Mutations in Patients With Hyaline Fibromatosis Syndrome and Proposal of a Modified Grading System

Juvenile hyaline fibromatosis (JHF) and infantile systemic hyalinosis (ISH) are rare, autosomal recessive disorders of the connective tissue caused by mutations in the gene encoding the anthrax toxin receptor 2 protein (ANTXR2) located on chromosome 4q21. Characteristically, these conditions present with overlapping clinical features, such as nodules and/or pearly papules, gingival hyperplasia, flexion contractures of the joints, and osteolytic bone defects. The present report describes a pair of sibs and three other JHF/ISH patients whose diagnoses were based on typical clinical manifestations and confirmed by histopathologic analyses and/or molecular analysis. A comparison of ISH and JHF, additional thoughts about new terminology (hyaline fibromatosis syndrome) and a modified grading system are also included. (C) 2012 Wiley Periodicals, Inc.

Molecular interactions: metal ions and protein chaperones in the urease system from Helicobacter pylori

Although nickel is a toxic metal for living organisms in its soluble form, its importance in many biological processes recently emerged. In this view, the investigation of the nickel-dependent enzymes urease and [NiFe]-hydrogenase, especially the mechanism of nickel insertion into their active sites, represent two intriguing case studies to understand other analogous systems and therefore to lead to a comprehension of the nickel trafficking inside the cell. Moreover, these two enzymes have been demonstrated to ensure survival and colonization of the human pathogen H. pylori, the only known microorganism able to proliferate in the gastric niche. The right nickel delivering into the urease active site requires the presence of at least four accessory proteins, UreD, UreE, UreF and UreG. Similarly, analogous process is principally mediated by HypA and HypB proteins in the [NiFe]-hydrogenase system. Indeed, HpHypA and HpHypB also have been proposed to act in the activation of the urease enzyme from H. pylori, probably mobilizing nickel ions from HpHypA to the HpUreE-HpUreG complex. A complete comprehension of the interaction mechanism between the accessory proteins and the crosstalk between urease and hydrogenase accessory systems requires the determination of the role of each protein chaperone that strictly depends on their structural and biochemical properties. The availability of HpUreE, HpUreG and HpHypA proteins in a pure form is a pre-requisite to perform all the subsequent protein characterizations, thus their purification was the first aim of this work. Subsequently, the structural and biochemical properties of HpUreE were investigated using multi-angle and quasi-elastic light scattering, as well as NMR and circular dichroism spectroscopy. The thermodynamic parameters of Ni2+ and Zn2+ binding to HpUreE were principally established using isothermal titration calorimetry and the importance of key histidine residues in the process of binding metal ions was studied using site-directed mutagenesis. The molecular details of the HpUreE-HpUreG and HpUreE-HpHypA protein-protein assemblies were also elucidated. The interaction between HpUreE and HpUreG was investigated using ITC and NMR spectroscopy, and the influence of Ni2+ and Zn2+ metal ions on the stabilization of this association was established using native gel electrophoresis, light scattering and thermal denaturation scanning followed by CD spectroscopy. Preliminary HpUreE-HpHypA interaction studies were conducted using ITC. Finally, the possible structural architectures of the two protein-protein assemblies were rationalized using homology modeling and docking computational approaches. All the obtained data were interpreted in order to achieve a more exhaustive picture of the urease activation process, and the correlation with the accessory system of the hydrogenase enzyme, considering the specific role and activity of the involved protein players. A possible function for Zn2+ in the chaperone network involved in Ni2+ trafficking and urease activation is also envisaged.

Lung on Chip: In vitro HGF effects on injured alveolar A549 epithelial cells in microfluidic system

Microfluidic systems have become competitive tools in the invitro modelling of diseases and promising alternatives to animal studies. They allow obtaining more invivo like conditions for cellular assays. Research in idiopathic pulmonary fibrosis could benefit from this novel methodological approach to understand the pathophysiology of the disease & develop efficient therapies. The use of hepatocyte growth factor (HGF) for alveolar reepithelisation is a promising approach. In this study, we show a new microfluidic system to analyse the effects of HGF on injured alveolar epithelial cells. Microfluidic systems in polydimethylsiloxane were fabricated by soft lithography. The alveolar A549 epithelial cells (10,000 cells) were seeded and studied in these microfluidic systems with media perfusion (1μl/30min). Injury tests were made on the cells by the perfusion with media containing H2O2 or bleomycin. The degree of injury was then assessed by a metabolic and an apoptotic assays. Wound assays were also performed with a central laminar flow of trypsin. Monitoring of wound closure with HGF vs control media was assessed. The alveolar A549 epithelial cells grew and proliferated in the microfluidic system. In the wound closure assay, the degree of wound closure after 5 hours was (53.3±1.3%) with HGF compared to (9.8±2.4%) without HGF (P <0.001). We present a novel microfluidic model that allows culture, injury and wounding of A549 epithelial cells and represents the first step towards the development of an invitro reconstitution of the alveolar-capillary interface. We were also able to confirm that HGF increased alveolar epithelial repair in this system.

Capillary electrophoretic investigation of the enantioselective metabolism of propafenone by human cytochrome P-450 SUPERSOMES: Evidence for atypical kinetics by CYP2D6 and CYP3A4

An enantioselective CE method was used to identify the ability of CYP450 enzymes and their stereoselectivity in catalyzing the transformation of propafenone (PPF) to 5-hydroxy-propafenone (5OH-PPF) and N-despropyl-propafenone (NOR-PPF). Using in vitro incubations with single CYP450 enzymes (SUPERSOMES), 5OH-PPF is shown to be selectively produced by CYP2D6 and N-dealkylation is demonstrated to be mediated by CYP2D6, CYP3A4, CYP1A2, and CYP1A1. For the elucidation of kinetic aspects of the metabolism with CYP2D6 and CYP3A4, incubations with individual PPF enantiomers and racemic PPF were investigated. With the exception of the dealkylation in presence of R-PPF only, which can be described by the Michaelis-Menten model, all CYP2D6-induced reactions were found to follow autoactivation kinetics. For CYP3A4, all NOR-PPF enantiomer formation rates as function of PPF enantiomer concentration were determined to follow substrate inhibition kinetics. The formation of NOR-PPF by the different enzymes is stereoselective and is reduced significantly when racemic PPF is incubated. Clearance values obtained for CYP3A4 dealkylation are stereoselective whereas those of CYP2D6 hydroxylation are not. This paper reports the first investigation of the PPF hydroxylation and dealkylation kinetics by the CYP2D6 enzyme and represents the first report in which enantioselective CE data provide the complete in vitro kinetics of metabolic steps of a drug.

Dynamic computer simulations of electrophoresis: three decades of active research

Dynamic models for electrophoresis are based upon model equations derived from the transport concepts in solution together with user-inputted conditions. They are able to predict theoretically the movement of ions and are as such the most versatile tool to explore the fundamentals of electrokinetic separations. Since its inception three decades ago, the state of dynamic computer simulation software and its use has progressed significantly and Electrophoresis played a pivotal role in that endeavor as a large proportion of the fundamental and application papers were published in this periodical. Software is available that simulates all basic electrophoretic systems, including moving boundary electrophoresis, zone electrophoresis, ITP, IEF and EKC, and their combinations under almost exactly the same conditions used in the laboratory. This has been employed to show the detailed mechanisms of many of the fundamental phenomena that occur in electrophoretic separations. Dynamic electrophoretic simulations are relevant for separations on any scale and instrumental format, including free-fluid preparative, gel, capillary and chip electrophoresis. This review includes a historical overview, a survey of current simulators, simulation examples and a discussion of the applications and achievements of dynamic simulation.

Sweet's syndrome involoving the musculoskeletal system during treatment of promyelocytic leukemia with all-trans retinoic acid

Induction therapy of promyelocytic leukemia with all-trans retinoic acid is a standard therapy despite significant side-effects. The most important, the "retinoic acid syndrome", consists of a hyperinflammatory reaction with capillary leakage (edema, pleural, and pericardial effusion), infiltration of myeloid cells into internal organs and systemic signs of inflammation. We describe here two cases of another hyperinflammatory reaction during all-trans retinoic acid therapy, the Sweet's syndrome, consisting of infiltrates of the skin and internal organs by neutrophilic granulocytes. Fever, painful erythematous cutaneous plaques, prominent musculoskeletal involvement (myositis, fasciitis), a sterile pulmonary infiltration and intercurrent proteinuria characterized the clinical course of all-trans retinoic acid-associated Sweet's syndrome. Treatment with glucocorticoids led to resolution of the syndrome within 48 h. Three other cases of all-trans retinoic acid-associated Sweet's syndrome without involvement of internal organs, prominent on our cases, were published previously. Recognition of ATRA-associated Sweet's syndrome is of practical importance.

Electrophoretically mediated microanalysis for characterization of the enantioselective CYP3A4 catalyzed N-demethylation of ketamine

Execution of an enzymatic reaction performed in a capillary with subsequent electrophoretic analysis of the formed products is referred to as electrophoretically mediated microanalysis (EMMA). An EMMA method was developed to investigate the stereoselectivity of the CYP3A4-mediated N-demethylation of ketamine. Ketamine was incubated in a 50 μm id bare fused-silica capillary together with human CYP3A4 Supersomes using a 100 mM phosphate buffer (pH 7.4) at 37°C. A plug containing racemic ketamine and the NADPH regenerating system including all required cofactors for the enzymatic reaction was injected, followed by a plug of the metabolizing enzyme CYP3A4 (500 nM). These two plugs were bracketed by plugs of incubation buffer to ensure proper conditions for the enzymatic reaction. The rest of the capillary was filled with a pH 2.5 running buffer comprising 50 mM Tris, phosphoric acid, and 2% w/v of highly sulfated γ-cyclodextrin. Mixing of reaction plugs was enhanced via application of -10 kV for 10 s. After an incubation of 8 min at 37°C without power application (zero-potential amplification), the capillary was cooled to 25°C within 3 min followed by application of -10 kV for the separation and detection of the formed enantiomers of norketamine. Norketamine formation rates were fitted to the Michaelis-Menten model and the elucidated values for V(max) and K(m) were found to be comparable to those obtained from the off-line assay of a previous study.

Sampling strategies for capillary isoelectric focusing with electroosmotic zone mobilization assessed by high-resolution dynamic computer simulation

The impact of initial sample distribution on separation and focusing of analytes in a pH 3–11 gradient formed by 101 biprotic carrier ampholytes under concomitant electroosmotic displacement was studied by dynamic high-resolution computer simulation. Data obtained with application of the analytes mixed with the carrier ampholytes (as is customarily done), as a short zone within the initial carrier ampholyte zone, sandwiched between zones of carrier ampholytes, or introduced before or after the initial carrier ampholyte zone were compared. With sampling as a short zone within or adjacent to the carrier ampholytes, separation and focusing of analytes is shown to proceed as a cationic, anionic, or mixed process and separation of the analytes is predicted to be much faster than the separation of the carrier components. Thus, after the initial separation, analytes continue to separate and eventually reach their focusing locations. This is different to the double-peak approach to equilibrium that takes place when analytes and carrier ampholytes are applied as a homogenous mixture. Simulation data reveal that sample application between two zones of carrier ampholytes results in the formation of a pH gradient disturbance as the concentration of the carrier ampholytes within the fluid element initially occupied by the sample will be lower compared to the other parts of the gradient. As a consequence thereof, the properties of this region are sample matrix dependent, the pH gradient is flatter, and the region is likely to represent a conductance gap (hot spot). Simulation data suggest that sample placed at the anodic side or at the anodic end of the initial carrier ampholyte zone are the favorable configurations for capillary isoelectric focusing with electroosmotic zone mobilization.

Dynamic high-resolution computer simulation of electrophoretic enantiomer separations with neutral cyclodextrins as chiral selectors.

GENTRANS, a comprehensive one-dimensional dynamic simulator for electrophoretic separations and transport, was extended for handling electrokinetic chiral separations with a neutral ligand. The code can be employed to study the 1:1 interaction of monovalent weak and strong acids and bases with a single monovalent weak or strong acid or base additive, including a neutral cyclodextrin, under real experimental conditions. It is a tool to investigate the dynamics of chiral separations and to provide insight into the buffer systems used in chiral capillary zone electrophoresis (CZE) and chiral isotachophoresis. Analyte stacking across conductivity and buffer additive gradients, changes of additive concentration, buffer component concentration, pH, and conductivity across migrating sample zones and peaks, and the formation and migration of system peaks can thereby be investigated in a hitherto inaccessible way. For model systems with charged weak bases and neutral modified β-cyclodextrins at acidic pH, for which complexation constants, ionic mobilities, and mobilities of selector-analyte complexes have been determined by CZE, simulated and experimentally determined electropherograms and isotachopherograms are shown to be in good agreement. Simulation data reveal that CZE separations of cationic enantiomers performed in phosphate buffers at low pH occur behind a fast cationic migrating system peak that has a small impact on the buffer composition under which enantiomeric separation takes place.

Optimized on-line enantioselective capillary electrophoretic method for kinetic and inhibition studies of drug metabolism mediated by cytochrome P450 enzymes.

Pharmacokinetic and pharmacodynamic properties of a chiral drug can significantly differ between application of the racemate and single enantiomers. During drug development, the characteristics of candidate compounds have to be assessed prior to clinical testing. Since biotransformation significantly influences drug actions in an organism, metabolism studies represent a crucial part of such tests. Hence, an optimized and economical capillary electrophoretic method for on-line studies of the enantioselective drug metabolism mediated by cytochrome P450 enzymes was developed. It comprises a diffusion-based procedure, which enables mixing of the enzyme with virtually any compound inside the nanoliter-scale capillary reactor and without the need of additional optimization of mixing conditions. For CYP3A4, ketamine as probe substrate and highly sulfated γ-cyclodextrin as chiral selector, improved separation conditions for ketamine and norketamine enantiomers compared to a previously published electrophoretically mediated microanalysis method were elucidated. The new approach was thoroughly validated for the CYP3A4-mediated N-demethylation pathway of ketamine and applied to the determination of its kinetic parameters and the inhibition characteristics in presence of ketoconazole and dexmedetomidine. The determined parameters were found to be comparable to literature data obtained with different techniques. The presented method constitutes a miniaturized and cost-effective tool, which should be suitable for the assessment of the stereoselective aspects of kinetic and inhibition studies of cytochrome P450-mediated metabolic steps within early stages of the development of a new drug.