ELECTROANALYSIS, Issue 13 2007
Lishi Wang
Abstract A novel low-cost instrument for arbitrary function large-amplitude Fourier transformed voltammetry was developed. Description of both hardware and software was given in detail in this paper. A micro-control-unit (MCU) in combination with a field programmable gate array (FPGA) was designed to act as the controller of the instrument. Profiting from the built-in USB2.0 standard interface of the MCU, vast amount of data to/from the high resolution digital-to-analog converter (DAC)/analog-to-digital converter (ADC) then could be exchanged with computer in real-time, instead of being temporarily stored at the capacity limited memory of the instrument which always restricted the length of sampling time and the size of the collected data set. In the [Fe(CN)6]4+/3+ system, by superimposing a sinusoidal waveform with an amplitude of 120,mV onto a triangular potential and then applying to a macro electrode through the instrument, voltammograms up to the eighth harmonic could be well resolved by FT-IFT method. Excellent agreement was attained with Bond's similar experiment [Anal. Chem. 76 (2004) 3619] in respect of the shape and relative peak height of each harmonic. With the simply structured instrument, stable performance, flexible and versatile function was achieved. Arbitrary forms of AC perturbation which may not necessarily be sinusoidal or square-wave or other regular formed periodic signal could be synthesized and superimposed onto a DC potential as the excitation signal with this instrument. Some more useful electrode process information was expected to unveil by utilizing the FT-IFT algorithm to dissect the response signal. [source]

Coupled HM analysis using zero-thickness interface elements with double nodes.

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 18 2008
Part I: Theoretical model
Abstract In recent years, the authors have proposed a new double-node zero-thickness interface element for diffusion analysis via the finite element method (FEM) (Int. J. Numer. Anal. Meth. Geomech. 2004; 28(9): 947,962). In the present paper, that formulation is combined with an existing mechanical formulation in order to obtain a fully coupled hydro-mechanical (or HM) model applicable to fractured/fracturing geomaterials. Each element (continuum or interface) is formulated in terms of the displacements (u) and the fluid pressure (p) at the nodes. After assembly, a particular expression of the traditional ,u,p' system of coupled equations is obtained, which is highly non-linear due to the strong dependence between the permeability and the aperture of discontinuities. The formulation is valid for both pre-existing and developing discontinuities by using the appropriate constitutive model that relates effective stresses to relative displacements in the interface. The system of coupled equations is solved following two different numerical approaches: staggered and fully coupled. In the latter, the Newton,Raphson method is used, and it is shown that the Jacobian matrix becomes non-symmetric due to the dependence of the discontinuity permeability on the aperture. In the part II companion paper (Int. J. Numer. Anal. Meth. Geomech. 2008; DOI: 10.1002/nag.730), the formulation proposed is verified and illustrated with some application examples. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Coupled HM analysis using zero-thickness interface elements with double nodes,Part II: Verification and application

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 18 2008
J. M. Segura
Abstract In a companion Part I of this paper (Int. J. Numer. Anal. Meth. Geomech. 2008; DOI: 10.1002/nag.735), a coupled hydro-mechanical (HM) formulation for geomaterials with discontinuities based on the finite element method (FEM) with double-node, zero-thickness interface elements was developed and presented. This Part II paper includes the numerical solution of basic practical problems using both the staggered and the fully coupled approaches. A first group of simulations, based on the classical consolidation problem with an added vertical discontinuity, is used to compare both the approaches in terms of accuracy and convergence. The monolithic or fully coupled scheme is also used in an application example studying the influence of a horizontal joint in the performance of a reservoir subject to fluid extraction. Results include a comparison with other numerical solutions from the literature and a sensitivity analysis of the mechanical parameters of the discontinuity. Some simulations are also run using both a full non-symmetric and a simplified symmetric Jacobian matrix. On top of verifying the model developed and its capability to reflect the conductivity changes of the interface with aperture changes, the results presented also lead to interesting observations of the numerical performance of the methods implemented. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Implicit integration of a chemo-plastic constitutive model for partially saturated soils

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 14 2008
H. W. Zhang
Abstract A chemo-plastic constitutive model for partially saturated soils is proposed in this paper based on the existing models developed in Hueckel (Int. J. Numer. Anal. Meth. Geomech. 1997; 21:43,72) and Gallipoli et al. (Geotechnique 2003; 53:123,135). The chemical softening effects due to the increase in contaminant mass concentration are considered based on Hueckel's chemo-plastic model. Gallipoli's model is used to simulate the effects of suction and degree of saturation on mechanical behavior of partially saturated porous materials. In order to implement the proposed model in a finite element code, a fully implicit backward-Euler integration algorithm is put forward. Numerical solutions for the tests at local level and the application of the algorithm to the real boundary value problem demonstrate the accuracy and convergence properties of the proposed integration scheme. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Lateral force and centroid location caused by horizontal and vertical surcharge strip loads on a cross-anisotropic backfill

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 13 2007
Cheng-Der Wang
Abstract This work presents analytical solutions for determining lateral force (force per unit length) and centroid location caused by horizontal and vertical surcharge surface loads acting on a cross-anisotropic backfill. The surcharge loading types are point load, line load, uniform strip load, upward linear-varying strip load, upward nonlinear-varying strip load, downward linear-varying strip load, and downward nonlinear-varying strip load. The planes of cross-anisotropy are assumed parallel to the backfill ground surface. The proposed solutions, derived by integrating the lateral stress solutions (Int. J. Numer. Anal. Meth. Geomech. 2005; 29:1341,1361), do not exist in literature. Clearly, the type and degree of material anisotropy, loading distance from the retaining wall, and loading types markedly impact the proposed solutions. Two examples are utilized to illustrate the type and degree of soil anisotropy, and the loading types on the lateral force and centroid location in the isotropic/cross-anisotropic backfills generated by the horizontal and vertical uniform, upward linear-varying and upward nonlinear-varying strip loads. The parametric study results demonstrate that the lateral force and centroid location accounting for soil anisotropy, loading distance from the retaining wall, dimension of the loading strip, and loading directions and types differ significantly from those estimated using existing isotropic solutions. The derived solutions can be added to other lateral pressures, such as earth pressure or water pressure, required for stability and structural analysis of a retaining wall. Additionally, they can simulate realistically actual surcharge loading problems in geotechnical engineering when backfill materials are cross-anisotropic. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Transient solution for a plane-strain fracture driven by a shear-thinning, power-law fluid

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 14 2006
D. I. Garagash
Abstract This paper analyses the problem of a fluid-driven fracture propagating in an impermeable, linear elastic rock with finite toughness. The fracture is driven by injection of an incompressible viscous fluid with power-law rheology. The relation between the fracture opening and the internal fluid pressure and the fracture propagation in mobile equilibrium are described by equations of linear elastic fracture mechanics (LEFM), and the flow of fluid inside the fracture is governed by the lubrication theory. It is shown that for shear-thinning fracturing fluids, the fracture propagation regime evolves in time from the toughness- to the viscosity-dominated regime. In the former, dissipation in the viscous fluid flow is negligible compared to the dissipation in extending the fracture in the rock, and in the later, the opposite holds. Corresponding self-similar asymptotic solutions are given by the zero-viscosity and zero-toughness (J. Numer. Anal. Meth. Geomech. 2002; 26:579,604) solutions, respectively. A transient solution in terms of the crack length, the fracture opening, and the net fluid pressure, which describes the fracture evolution from the early-time (toughness-dominated) to the large-time (viscosity-dominated) asymptote is presented and some of the implications for the practical range of parameters are discussed. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Directional response of a reconstituted fine-grained soil,Part I: experimental investigation

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 13 2006
Daniele Costanzo
Abstract This paper discusses the results of a large experimental program designed to investigate in a systematic manner the main features of the incremental response of fine-grained soils. The results are obtained from triaxial stress probing experiments carried out on a French silty clay (Beaucaire Marl). All the tests have been performed on reconstituted specimens, normally consolidated to an initial state which is either isotropic or anisotropic. In the interpretation of the experimental results, extensive use is made of the concept of strain response envelope. The response envelopes obtained for different stress increment magnitudes are remarkably consistent with each other and indicate an inelastic and irreversible material response, i.e. a strong dependence on the stress increment direction, also at relatively small strain levels. A companion paper (Int. J. Numer. Anal. Meth. Geomech., this issue, 2006) assesses the performance of some advanced constitutive models in reproducing the behaviour of reconstituted Beaucaire Marl as observed in this experimental program. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Incrementalization of a single hardening constitutive model for frictional materials

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2002
P. V. Lade
Abstract The governing equations for an elasto-plastic constitutive model for frictional materials such as soil, rock, and concrete are presented, and the incremental form is indicated in preparation for implementation of the model in a user-defined module for finite element calculations. This isotropic, work-hardening and -softening model employs a single yield surface, it incorporates non-associated plastic flow, and its capability of capturing the behaviour of different types of frictional materials under various three-dimensional conditions has been demonstrated by comparison with measured behaviour, as presented in the literature. The incrementalization procedure is indicated and the resulting equations for the single hardening model are presented together with parameters for a dense sand. Following the implementation of the model, these parameters are used for evaluation of different integration schemes as presented in a companion paper by Jakobsen and Lade (Int. J. Numer. Anal. Meth. Geomech. 2002; 26:661). Copyright © 2002 John Wiley & Sons, Ltd. [source]

Implementation algorithm for a single hardening constitutive model for frictional materials

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2002
K. P. Jakobsen
Abstract An advanced elasto-plastic constitutive model for frictional materials, whose incremental version is presented in a companion paper (Int. J. Numer. Anal. Meth. Geomech., 2002; 26:647), is implemented in a user-defined material module. The general calculation strategy inside this module is presented and discussed, including the initial intersection of the yield surface and the techniques for updating of stresses and hardening modulus. Several integration schemes are implemented in the module and their capabilities in relation to the advanced, three-dimensional constitutive model are evaluated. The forward Euler, modified Euler, and Runge,Kutta,Dormand,Prince integration schemes are explained in detail, compared, and evaluated in view of error tolerances and computational efficiency. Copyright © 2002 John Wiley & Sons, Ltd. [source]

A new hybrid velocity integration method applied to elastic wave propagation

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2008
Zhiyun Chen
Abstract We present a novel space,time Galerkin method for solutions of second-order time-dependent problems. By introducing the displacement,velocity relationship implicitly, the governing set of equations is reformulated into a first-order single field problem with the unknowns in the velocity field. The resulting equation is in turn solved by a time-discontinuous Galerkin approach (Int. J. Numer. Anal. Meth. Geomech. 2006; 30:1113,1134), in which the continuity between time intervals is weakly enforced by a special upwind flux treatment. After solving the equation for the unknown velocities, the displacement field quantities are computed a posteriori in a post-processing step. Various numerical examples demonstrate the efficiency and reliability of the proposed method. Convergence studies with respect to the h - and p -refinement and different discretization techniques are given. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Serum KL-6 levels in lung cancer patients with or without interstitial lung disease

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 5 2010
Kunihiko Miyazaki
Abstract Background: It is not known whether lung cancer patients with interstitial lung disease (ILD) might have higher serum levels of KL-6, a high molecular weight glycoprotein classified as a polymorphic epithelial mucin. In addition, prognosis of these patients with elevated serum KL-6 levels might be poorer than that with normal KL-6 levels, but it has not been well clarified. Methods: Serum KL-6 levels in 273 lung cancer patients with or without ILD, and prognostic significance of elevated serum KL-6 levels in these patients were studied using uni- and multivariate analyses. Results: Serum KL-6 levels were elevated (>500,U/ml) in 73.5% of lung cancer patients with ILD and in 33.7% of those without ILD. Serum KL-6 levels in lung cancer patients with ILD were significantly higher than those without ILD. In lung cancer patients with ILD, elevated serum KL-6 has no prognostic significance, but in those without ILD, however, it was one of the unfavorable prognostic factors. Conclusions: Elevated serum KL-6 levels can be observed in lung cancer patients both with and without ILD. Having ILD has strong prognostic impact in patients with lung cancer. In those without ILD, however, elevated KL-6 levels may be related to poor prognosis. J. Clin. Lab. Anal. 24:295,299, 2010. © 2010 Wiley-Liss, Inc. [source]

Re-evaluation of cord blood arterial and venous reference ranges for pH, pO2, pCO2, according to spontaneous or cesarean delivery

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 5 2010
K. Kotaska
Abstract Umbilical cord blood gas analysis (pO2 and pCO2) is now recommended in all high-risk baby deliveries and in some centers it is performed routinely following all deliveries. The aim of this study was to re-evaluate cord blood arterial and venous reference ranges for pH, pO2, pCO2 in newborns, delivered by spontaneous vaginal delivery (SVD) and by cesarean section (CS) performed in Faculty Hospital Motol. Two groups of subjects were selected for the study. Group I consisted of 303 newborns with SVD. Group II consisted of 189 newborns delivered by cesarean section. Cord blood samples were analyzed for standard blood gas and pH, using the analytical device Rapid Lab 845 and Rapid Lab 865. We obtained reference values expressed as range (lower and upper reference value expressed as 2.5 and 97.5 percentiles) for cord blood in newborns with SVD: arterial cord blood: pH=7.01,7.39; pCO2=4.12,11.45,kPa; pO2=1.49,5.06,kPa; venous cord blood: pH=7.06,7.44; pCO2=3.33,9.85,kPa; pO2=1.80,6.29,kPa. We also obtained reference values for cord blood in newborns delivered by CS: arterial cord blood: pH=7.05,7.39; pCO2=5.01,10.60,kPa; pO2=1.17,5.94,kPa; venous cord blood: pH=7.10,7.42; pCO2=3.88,9.36,kPa; pO2=1.98,7.23,kPa. Re-evaluated reference ranges play essential role in monitoring conditions of newborns with spontaneous and caesarean delivery. J. Clin. Lab. Anal. 24:300,304, 2010. © 2010 Wiley-Liss, Inc. [source]

Rapid mycoplasma culture for the early diagnosis of Mycoplasma pneumoniae infection

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 4 2010
Ling-di Ma
Abstract Early diagnosis of Mycoplasma pneumoniae (Mp) plays a pivotal role in its management. We evaluated the role of rapid culture method in early diagnosis of Mp infection and discussed the potential impact factors. A total of 2,600 patients with acute respiratory infection were included, and their pharyngeal swab samples were prepared for Mp rapid culture based on selective Mp fluid culture medium. The clinical contributing factors related to Mp infection were also explored. The positive rate of Mp culture in females was 41.75%, which was higher than that for males (37.63%). Mp infections were incidental to the children and elderly. The positive rates of Mp culture were higher in children aged 3,5 years and adults older than 70 years (54.05 and 31.48%, respectively), compared with other ages. In addition, Mp infection frequently occurred in winter (December,February) and spring (March,May), with significantly higher positive rates of Mp culture by 40.02 and 42.89 vs. 32.15 and 33.50% in summer (June,August) and autumn (September,November), respectively. The positive rate of rapid culture for Mp was slightly higher than that by Mp antibody assay, but the diagnostic accordance was well between these two methods (P>0.05). Furthermore, clinical common symptoms of respiratory tract infection, such as fever, cough, and expectoration, were not found specific in Mp infection, suggesting that they were not independent prognostic predictors for Mp infection. Therefore, rapid culture based on the Mp pathogen detection would have important clinical application for the early diagnosis of Mp infection. J. Clin. Lab. Anal. 24:224,229, 2010. © 2010 Wiley-Liss, Inc. [source]

Determination of cut-off titers and agreement between immunofluorescence and immunoblotting methods for detecting antinuclear antibodies in children

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 4 2010
G. Aksu
Abstract Detection of antinuclear antibodies (ANA) is a diagnostic adjunct in patients with suspected autoimmune connective tissue diseases, and various detection methods are in use. The aim of this study was to analyze the agreement between the ANA immunoflourescence (IF) and immunoblotting (IB) methods and determine cut-off for children subjects in a laboratory setting. We evaluated 729 serum samples that were analyzed by both ANA IF and IB. The results were evaluated by ,2 test and, for agreement, , index was used. Frequencies determined for both 1:40,1:100 cut-off titers of ANA IF in relation to IB testing supported the idea that 1:100 starting dilution should be recommended in children subjects for ANA IF method and antigen specific immunoblot testing was needed, especially for some of the ANA IF negative samples. Agreement between the two methods, especially with homogenous, granular, and nucleolar ANA IF patterns, was statistically significant. J. Clin. Lab. Anal. 24:230,236, 2010. © 2010 Wiley-Liss, Inc. [source]

Quantification of urinary 8-iso-prostaglandin F2, using liquid chromatography,tandem mass spectrometry during cardiac valve surgery

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 4 2010
Yun-Hui Teng
Abstract Oxidative stress is an unavoidable event during many complex surgical procedures. 8-iso-prostaglandin F2, (8-iso-PGF2,) is a reliable biomarker for the evaluation of oxidative stress in vivo. The aim of this study is to develop simple and accurate liquid chromatography,tandem mass spectrometry (LC-MS/MS) methods for the detection of urinary 8-iso-PGF2, in samples collected from patients who received a cardiopulmonary bypass (CPB) during cardiac valve surgery. Urine samples of 14 patients with cardiac valve diseases were collected before, during, and after CPB. The level of 8-iso-PGF2, was detected via selected-reaction monitoring triple quadrupole MS/MS and the result was compared with 12 healthy volunteers. The method's detection limit (3S/N) was 0.25,pg for 8-iso-PGF2,, with a linear working range of 0.25,20,ng/ml. For patients with cardiac valve disease, the 8-iso-PGF2, levels before the bypasses were the same as those of healthy individuals (P>0.05) and the 8-iso-PGF2, levels during and after CPB were significantly higher than those before the bypasses (P<0.05). In conclusion, we present a simple and specific protocol for LC-MS/MS quantification of urinary 8-iso-PGF2, collected during CPB. Using this technique, it would be feasible to assess the levels of oxidative stress during cardiac surgery and thereby helpful for the management of oxidative injury. J. Clin. Lab. Anal. 24:237,245, 2010. © 2010 Wiley-Liss, Inc. [source]

Evaluation of the alkaline wash/lysis procedure for the molecular diagnosis of a positive bacterial blood culture in clinical routine practice

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 3 2010
Sheng-Chuan Hsi
Abstract Blood culture is commonly used to detect microorganisms in patients with a suspected blood infection. This study evaluated the alkaline wash/lysis procedure to extract DNA of microorganisms in a clinical blood culture. A multiplex polymerase chain reaction (PCR) targeting the 16S rDNA (ribosomal DNA) gene and the fungal ITS (internal transcribed spacer) gene was used as a reliable indicator for the presence of microorganism DNA in the extracts. A total of 535BacT/ALERT positive blood culture bottles were evaluated. Multiplex PCR showed positive results in 530 DNA extracts, but 5 DNA extracts gave negative results. We conclude that the alkaline wash/lysis procedure in combination with the multiplex PCR is a simple and sensitive method, which can be used in a standard diagnostic laboratory to detect microorganisms in blood culture material. J. Clin. Lab. Anal. 24:139,144, 2010. © 2010 Wiley-Liss, Inc. [source]

Candida dubliniensis screening using the germ tube test in clinical yeast isolates and prevalence of C. dubliniensis in Korea

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 3 2010
Tae-Hyoung Kim
Abstract The aim of this study was to screen for C. dubliniensis using the germ tube test with human pooled serum (HPS) in clinical isolates and investigate the prevalence of C. dubliniensis in Korea. Among 1,854 yeast strains isolated, 1,404 strains of C. albicans (on the basis of positive results of the germ tube test) and 192 germ tube-negative yeast strains were examined. All 1,596 clinical isolates were examined using the germ tube test with HPS, the differential temperature, and NaCl tolerance test. Only 81 isolates that did not grow at 45°C nor on Sabouraud 6.5% NaCl broth were selected and tested using the VITEK 2 ID-YSTsystem and the multiplex-PCR assay for the study. The two strains, C. dubliniensis ATCC MYA-646 and KCTC 17427 failed to produce germ tubes in HPS but produced them in fresh rabbit serum (FRS) and fetal bovine serum (FBS). No C. dubliniensis was found in this study population. The results of this study suggest that the germ tube test with HPS in combination with FRS or FBS can be used for discriminating between C. albicans and C. dubliniensis strains and that the prevalence of C. dubliniensis appears to be extremely low in Korea. J. Clin. Lab. Anal. 24:145,148, 2010. © 2010 Wiley-Liss, Inc. [source]

Oxidative damage to DNA and lipids: correlation with protein glycation in patients with type 1 diabetes

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 2 2010
Mohammad Taghi Goodarzi
Abstract Diabetic hyperglycemia is associated with increased production of reactive oxygen species (ROS). ROS reacts with DNA resulting in various products, such as 8-hydroxydeoxyguanosine (8-OHdG), that excrete in urine owing to DNA repair processes. Urinary 8-OHdG has been proposed as an indicator of oxidative damage to DNA. This study aimed to evaluate relationship between oxidative damage to DNA and protein glycation in patients with Type 1 diabetes. We measured urinary 8-OHdG level in diabetic patients and healthy subjects and discussed its relationship to glycated hemoglobin (HbA1c) and glycated serum protein (GSP) levels. Furthermore plasma malondialdehyde (MDA) level monitored as an important indicator of lipid peroxidation in diabetes. We studied 32 patients with Type 1 diabetes mellitus and compared the measured factors with those of 48 age-matched nondiabetic controls. GSP and MDA were measured bycolorimetric assay. Urinary 8-OHdG measurement was carried out using ELISA. In this study urinary 8-OHdG, HbA1c, plasma MDA, and GSP levels were progressively higher in diabetics than in control subjects (P<0.05). Furthermore we found significant correlation between urinary 8-OHdG and HbA1c (P<0.05) in diabetic group. Correlation between fasting blood sugar and GSP were significant. We also found significant correlation between fasting blood sugar and MDA. This case,control study in young diabetic patients showed increased blood glucose and related metabolic disorders result in oxidative stress and oxidative damage to DNA and lipids. Furthermore oxidative damage to DNA is associated to glycemic control level, whereas lipid peroxidation level was not significantly correlated with glycemic control level. J. Clin. Lab. Anal. 24:72,76, 2010. © 2010 Wiley-Liss, Inc. [source]

Myth and reality: practical test system for the measurement of anti-DNA antibodies in the diagnosis of systemic lupus erythematosus (SLE)

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 2 2010
Laura J. McCloskey
Abstract The myth persists that only the labor intensive Farr radioimmunoassay and Crithidia luciliae immunofluorescence (CL-IFA) are systemic lupus erythematosus (SLE)-specific tests. We compared them to ELISA with bacteriophage , DNA (EL-dsDNA) and denatured calf thymus DNA (EL-ssDNA). By percentile ranking, the specificity cut-off level was set both out of clinical context (SOCC) on 100 blood bank donors, and in clinical context (SICC) on 100 patients with either rheumatoid arthritis or scleroderma (50/50). Clinical sensitivity was calculated on 100 random SLE patients. At 95% SICC, the sensitivity of Farr, CL-IFA, EL-dsDNA, and EL-ssDNA was similar (95%CI): 76% (66,84), 76% (66,84), 63% (53,72), and 75% (65,83), respectively; 87% of the patients were positive by at least one method and 55%by all methods. At 99% SICC, the sensitivity was also similar (95% CI): 57% (47,67), 47% (37,57), 58% (47,67), and 43% (33,53), respectively. The areas under ROC curve were similar (95% CI) when patients were used as controls for specificity. At 99% SOCC, EL-ssDNA identified 89% positive, 2 negative but positive by another method at 95% SICC, and 9 negative (i.e. 89/2/9), followed by CL-IFA (80/6/14), Farr (76/12/12), and EL-dsDNA (64/23/13). Thus, at relatively low cost and easy automation, under the same conditions of specificity, the two ELISA tests combined were at least as good, if not superior, to CL-IFA or Farr: they showed similar clinical sensitivity and also identified more patients with anti-DNA antibodies. J. Clin. Lab. Anal. 24:77,84, 2010. © 2010 Wiley-Liss, Inc. [source]

Correlates of NT-proBNP concentration in patients with essential hypertension in absence of congestive heart failure

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 1 2010
Keizo Toda
Abstract Background: N-terminal proBNP (NT-proBNP) is widely used as a diagnostic biomarker and for the risk stratification of patients with heart failure (HF). Its role in the evaluation of patients with essential hypertension (EHT) is less clear. We examined the relationship between NT-proBNP concentrations and various clinical characteristics in hypertensive patients without HF. Methods: This study included 186 consecutive patients with EHT and no history of HF, ischemic heart disease, or atrial fibrillation. Single and multiple variable regression analyses were performed in search of clinical correlates of NT-proBNP concentrations. Results: In patients with EHT, median serum concentration of NT-proBNP was 73,pg/ml, and interquartile range (IQR) was 40,128,pg/ml. NT-proBNP was significantly higher (P<0.001) in women (87,pg/ml; IQR 55,137,pg/ml) than in men (52,pg/ml; IQR 24,115,pg/ml). Age (r=0.371, P<0.001), precordial QRS voltage (r=0.223, P<0.001), hemoglobin (Hgb) concentration, (r=,0.208, P=0.023) and estimated glomerular filtration rate (r=,0.139, P=0.044) were correlated with log-transformed NT-proBNP by multiple variable analysis. In men, age (r=0.453, P<0.001) and QRS voltage (r=0.283, P=0.004), and in women age (r=0.299, P=0.006), QRS voltage (r=0.212, P=0.019), Hgb (r=,0.182, P=0.049), and estimated glomerular filtration rate (r=,0.272, P=0.009) were correlated with serum concentrations of NT-proBNP. Conclusions: Age, gender, Hgb, left ventricular hypertrophy and renal function were correlated with NT-proBNP in patients with EHT. J. Clin. Lab. Anal. 24:12,16, 2010. © 2010 Wiley-Liss, Inc. [source]

Pigment epithelium-derived factor as a new marker of metabolic syndrome in Caucasian population

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 1 2010
D. Stejskal
Abstract Authors present that serum pigment epithelium derived factor (PEDF) is an independent marker of metabolic syndrome in Caucasianpopulation. PEDF was measured with new ELISA sandwich test. J. Clin. Lab. Anal. 24:17,19, 2010. © 2010 Wiley-Liss, Inc. [source]

A novel genetic variant of BMP2K contributes to high myopia

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 6 2009
Hsin-Ping Liu
Abstract Loss of eye growth regulation may cause myopia, because modulation of optic globe size is essential for the generation of normal optic power. Evidence has implied variations of BMP2 gene expression mediate ocular development and retinal tissue remodeling. Given BMP2 as a potential regulator involved in myopia development, we investigate whether gene BMP2-inducible kinase (BMP2K, BIKe), whose expression is up-regulated during BMP2-induced osteoblast differentiation, contributes to susceptibility of high myopia. Participants grouped into high myopia had a spherical equivalent greater than ,6.00 D, compared with a control group of spherical equivalent less than ,0.5 D. Genotyping of polymorphisms 1379 G/A (rs2288255) and 3171 C/G (rs12507099), corresponding with 405 Gly/Ser and 1002 Thr/Ser variation in the BMP2K gene were determined by PCR-restriction fragment length polymorphism and associative study performed by comparing high myopic subjects and healthy controls. The frequency of A allele in the BMP2K gene 1379 G/A polymorphism showed a significant difference between cases and controls (P<0.001, OR=2.99, 95% CI=1.62,5.54) and subjects with either AA or AG genotype show higher risk than GG genotype (P<0.001, OR=3.07, 95% CI=1.59,5.92), while 3171 C/G polymorphism was not significant from this survey. These data suggest that BMP2K gene 1379 G/A variant is strongly correlated with high myopia and may contribute to a genetic risk factor for high degrees of myopic pathogenesis. J. Clin. Lab. Anal. 23:362,367, 2009. © 2009 Wiley-Liss, Inc. [source]

AML1 amplification and 17q25 deletion in a case of childhood acute lymphoblastic leukemia

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 6 2009
Tuna Gulten
Abstract We report a case of childhood acute lymphoblastic leukemia (ALL) with both acute myeloid leukemia 1 (AML1) amplification and 17q25 deletion. AML1 gene is located on 21q22 and encodes a transcription factor. AML1 amplification is a common finding in childhood ALL, and itis observed as an increase in gene copy number by the FISH analysis. The mechanism of AML1 amplification is not associated with AML1 gene mutations. The 17q25 is a gene-rich chromosomal location and distinct abnormalities of this region have been observed in previous cases of different kinds of leukemia. Deletion of the 17q25 region has been reported in two leukemia patients. Septin 9 (SEPT9) and survivin genes are located on 17q25. High expression of these genes and AML1 amplification are regarded as markers in tumorigenesis and disease progression; however, more data are needed for accurate prognostic evaluation. J. Clin. Lab. Anal. 23:368,371, 2009. © 2009 Wiley-Liss, Inc. [source]

An improved microalbumin method (µALB_2) with extended analytical measurement range evaluated on the ADVIA® chemistry systems

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 5 2009
Pradip Datta
Abstract Quantitative determination of albumin (ALB) in human urine is important to assess kidney functions in a variety of diseases. Recently, Siemens released an improved Microalbumin assay (µALB_2) to measure urinary ALB on the automated, random access ADVIA 1650/1800, ADVIA 2400, and ADVIA 1200 Chemistry Systems. We evaluated analytical performances of this new method. All ADVIA Chemistry Systems use the same microalbumin reagent packs, µALB_2 calibrators, and commercial controls. The within-run and total CVs of the improved method with two-level BioRad Liquichek Urine Chemistry controls (,2 and 9,mg/dl ALB) and a urine pool (,29,mg/dl ALB) on all ADVIA Chemistry systems were <4.1 and <6.1%, respectively (40 replicates per sample). The analytical range/linearity of the method (all ADVIA systems) was from 0.3,mg/dl to theALB concentration in the highest level of calibrator (,38,42,mg/dl). The improved method (µALB_2) on the ADVIA 1650/1800 (y) correlated well with both the Beckman DXC 800 Microalbumin and the old microalbumin method on the ADVIA 1650/1800 analyzers. The improved method showed <10% interference with 16 chemicals from acetaminophen to uric acid that may be present in urine. The improved method has a minimum of 60 days' on-system stability on all systems with the calibration frequencies of (with/without a Reagent Container insert) 20/30 days (ADVIA1200), 50/60 days (ADVIA1650/1800), and 20/60 days (ADVIA2400). No prozone was observed with the method on any platform up to the highest ALB concentration tested in a sample (4,000,mg/dl). J. Clin. Lab. Anal. 23:314,318, 2009. © 2009 Wiley-Liss, Inc. [source]

Oxidative status in iron-deficiency anemia

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 5 2009
Jong-Ha Yoo
Abstract Oxidative stress is an imbalance between free radicals and antioxidant molecules that can play an important role in the pathogenesis of iron-deficiency anemia (IDA). The aim of this study was to investigate oxidative status in patients with IDA and alteration of oxidative status after iron treatment. Thirty-three female patients with IDA and 25 healthy controls were included in this study. Oxidant and total antioxidant capacity were determined using free oxygen radicals test and free oxygen radicals defence (Form CR 3000, Callegari, Parma, Italy). Catalase activity was measured by spectrophotometer using a commercially available kit (Bioxytech Catalase-520, OxisResearch, Portland, OR). Oxidant activity in patients with IDA was significantly higher than controls (P<0.05), while total antioxidant and catalase activity were significantly lower (P<0.05). After treatment, oxidant, antioxidant, and catalase activity reached the levels of the control group, and no significant differences were observed among groups (P>0.05). In conclusion, our data indicate that blood reactive oxygen species was lower and total antioxidant and catalase activity were higher after rather than before treatment in patients with IDA. The results of our study support the higher oxidative stress hypothesis in IDA; however, due to the limited number of cases included, more studies may be required to confirm the results. J. Clin. Lab. Anal. 23:319,323, 2009. © 2009 Wiley-Liss, Inc. [source]

Simultaneous use of direct and indirect diagnostic techniques in atypical respiratory infections from Chlamydophila pneumoniae and Mycoplasma pneumoniae

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 4 2009
S. Pignanelli
Abstract In 2008, 50 samples (BAL), coming from hospital patients, with acute respiratory symptoms have been investigated using two real-time PCR methods: one assay for the single detection of Chlamydophila pneumoniae and Mycoplasma pneumoniae DNA and one commercially available real-time duplex PCR assay for the detection of C. pneumoniae and M. pneumoniae DNA. Both techniques used here showed compliant results, with 100% concordance for detection of C. pneumoniae and 98% for detection of M. pneumoniae. The positive results obtained agreed with the clinical suspicion of such infections in some cases and with the presence of IgM specific for C. pneumoniae and M. pneumoniae in all cases of acute infection. J. Clin. Lab. Anal. 23:206,209, 2009. © 2009 Wiley-Liss, Inc. [source]

Anticardiolipin antibodies in the sera of patients with diagnosed chronic fatigue syndrome

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 4 2009
Yoshitsugi Hokama
Abstract Examination of anticardiolipin antibodies (ACAs) in the sera of patients clinically diagnosed with chronic fatigue syndrome (CFS) using an enzyme-linked immunoassay procedure demonstrated the presence of immunoglobulin M isotypes in 95% of CFS serum samples tested. The presence of immunoglobulin G and immunoglobulin A isotypes were also detected in a subset of the samples. Future studies will focus on elucidating whether alterations to mitochondrial inner membranes and/or metabolic functions play a possible role in the expression of ACAs. J. Clin. Lab. Anal. 23:210,212, 2009. © 2009 Wiley-Liss, Inc. [source]

Binding of anti-HLA class I antibody to endothelial cells produce an inflammatory cytokine secretory pattern,

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 3 2009
Eduardo Reyes-Vargas
Abstract Current methods are inadequate for the diagnosis of early chronic allograft rejection. The goal of this study was to determine whether ligation of anti-HLA antibodies to endothelial cells is associated with a distinctive cytokine secretory pattern. Human iliac artery endothelial cells (HIAEC) cultured in vitro were incubated with w6/32, an anti-HLA class I mAb. Culture supernatants collected daily for up to 4 days were tested for secretion of 13 cytokines using a multiplexed fluorescent microsphere immunoassay. Culture of HIAEC with medium containing mAb w6/32 supported the growth of HIAEC during the 4-day study period. Levels of the pro-inflammatory cytokines IL-1,, IL-6, IL-8, and TNF-, became significantly increased in supernatants of HIAEC incubated with the mAb w6/32. We conclude that ligation of anti-HLA class I antibodies to HLA class I antigens in endothelial cells initiates an acute inflammatory process and detecting an inflammatory cytokine secretory pattern might be useful to diagnose sub-clinical chronic allograft rejection. J. Clin. Lab. Anal. 23:157,160, 2009. © 2009 Wiley-Liss, Inc. [source]

Evaluation of extracts of Jatropha curcas and Moringa oleifera in culture media for selective inhibition of saprophytic fungal contaminants

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 3 2009
Grace Mebi Ayanbimpe
Abstract Most fungi occur in nature and utilize simple sources of carbohydrates and nitrogen for growth. Sabouraud's dextrose agar has been an ideal medium for primary isolation of fungi from clinical specimens, but for specimens from nonsterile sites or heavily contaminated ones, it has been necessary to include inhibitory substances such as antibiotics like chloramphenicol (antibacterial) and cycloheximide (antifungal). The problems we have in the our laboratory owing to frequent contamination of cultures and the delays in the procurement of cycloheximide have stimulated a search for alternatives in our local environment to enhance effective laboratory diagnoses of fungal infections. Purified extracts of the leaves and bark of Jatropha curcas and Moringa oleifera (common plants in our locality) were tested against clinical isolates of fungi at various concentrations to determine the minimum inhibitory concentration at which common fungal contaminants are inhibited, without affecting the growth of the pathogenic fungi sought for. At a concentration of 0.75,mg,ml,1 contaminants were totally inhibited by the leaf extracts. The bark extracts did not inhibit any fungus even at higher concentrations. From the results it was evident that the leaf extracts of both plants have potentials for use as inhibitory substances in culture media against contaminant fungi including Aspergillus spp., Penicillium spp., etc. J. curcas and M. oleifera are very common plants in our locality. They can be obtained at almost no cost and at any time needed. The benefits of these findings to mycology laboratories in a developing country are enormous. J. Clin. Lab. Anal. 23:161,164, 2009. © 2009 Wiley-Liss, Inc. [source]

Diagnostic assay of chromium (VI) in the ex vivo fluid of the urine of a smoker using a fluorine-doped handmade sensor

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 2 2009
Suw Young Ly
Abstract A voltammetric diagnosis of a chromium (VI) ion was investigated using a fluorine-doped graphite pencil electrode. Square wave (SW) stripping working conditions were attained at a high range of 0.051,0.45,mg,L,1 and a microrange of 0.05,0.4,µg,L,1 in a 0.1,M NH4H2PO4 electrolyte solution, at a relative standard deviation of 1.68% (RSD, n=15), using 10.0,µg,L,1 Cr(VI). A fast experimental time was used only for the 120,sec SW accumulation time. An analytical detection-limit (DL) of 0.008,µg,L,1 was attained. DL appeared to be more sensitive than common voltammetric and spectrophotometric assays. The developed sensor was applied to tap water and the urine of a smoker. It was found that the methods can be applicable for in vivo fluid or medicinal diagnosis. J. Clin. Lab. Anal. 23:82,87, 2009. © 2009 Wiley-Liss, Inc. [source]