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PubMed1990

Pyridoxine-derived B6 vitamers and pyridoxal 5'-phosphate-binding proteins in cytosolic and nuclear fractions of HTC cells.

The nuclear fraction of rat hepatoma-derived HTC cells contained approximately 8% of the total cellular pyridoxal 5'-phosphate. HTC cells were able to metabolize [3H]pyridoxine to coenzymatically active pyridoxal 5'-phosphate and pyridoxamine 5'-phosphate. As HTC cells did not have any demonstrable pyridoxine-5'-phosphate oxidase activity, the conversion of pyridoxine to pyridoxal 5'-phosphate must have taken place by a nonconventional route. The ratio of pyridoxal 5'-phosphate to pyridoxamine 5'-phosphate in the nonnuclear fraction of HTC cells was approximately 1:1, whereas in the nuclear fraction it was approximately 17:1, indicating that there was selective acquisition of pyridoxal 5'-phosphate by the nucleus. With the aid of a monoclonal antibody specific for the 5'-phosphopyridoxyl group, it was shown that there was one major pyridoxal 5'-phosphate-binding protein in a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)-resolved nucleoplasmic extract of HTC cells. This finding was confirmed by radioautography of an SDS-PAGE-resolved nucleoplasmic extract obtained from cells grown in a medium containing [3H]pyridoxine. Isoelectric focusing followed by SDS-PAGE also indicated the presence of one major pyridoxal 5'-phosphate-binding protein in the nucleoplasmic extract of HTC cells having a relatively high isoelectric point (approximately 7). Data were obtained indicating that the protein might exist in a higher molecular weight form, probably a dimer. Currently, these findings constitute virtually all of the available information on vitamin B6 and the cell nucleus.

Animals↗

PubMed1985

Platelet membrane proteins.

Studies on platelet membrane proteins during the past decade have defined a series of such components and their roles in key phenomena in hemostasis and thrombosis such as platelet adhesion and aggregation. Central among the membrane proteins is the glycoprotein group. At this time, several of these proteins have been characterized as to apparent molecular weights and subunit composition whereas sugar and amino acid composition and sequences await further studies for most of them. The absence of specific membrane glycoproteins in congenital bleeding diseases has helped to identify their functions as receptors for known ligands for binding reactions central to the hemostatic mechanism. Some of the membrane proteins may exist more or less loosely attached to each other on the surface of intact platelets, and this may be important for their functions.

Bernard-Soulier Syndrome↗

PubMed1986

Changes in gene expression in established human mammary tumor cell lines when compared with normal breast and breast tumor tissue.

RNA complexity analyses of total cellular polyadenylate-containing RNA isolated from lactating human breast tissue, human breast tumor tissue, and a mixture of established cell lines of mammary origin demonstrate extensive homology between the tissue RNA populations but suggest a decrease in the complexity of cell line nuclear RNA populations, with the exception of an early-passage MCF-7 cell line. Cell-free protein synthesis and two-dimensional gel electrophoresis also show quantitative and qualitative differences in gene expression between human mammary tumor tissue and reduction mammoplasty or established mammary cell lines of early and late passage number. The results demonstrate a major role for transcriptional and posttranscriptional mechanisms in the regulation of gene expression in the human mammary gland and show that studies on mammary gland gene expression using established cell lines of mammary origin reflect only in part gene expression in normal lactating human breast or breast tumor tissues.

Breast↗

PubMed1993

[An approach to evaluation methods for laboratory work].

Evaluation methods were proposed for quality control, normal range calculation and laboratory diagnosis. As a quality control method, the Xbar-R control chart should be evaluated with an error detection chart or with operating characteristic functions. Normal range calculation was evaluated by three parameters, accuracy, precision and robustness which represents stability against abnormal data contamination. Prior to evaluating the laboratory diagnosis, patient data were plotted on a three dimensional chart, a star map, to determine whether apparent clusters were formed. Laboratory diagnosis is a process of reduction of multivariate medical information, and it develops new parameters related to the pathological state of the patient. The method was evaluated using entropy calculation or average count of abnormal parameters.

Clinical Laboratory Techniques↗

PubMedDate not supplied

The effects of ankle-foot orthoses on the ankle and knee in persons with myelomeningocele: an evaluation using three-dimensional gait analysis.

The purpose of this study was to determine the effects of the ankle-foot orthosis (AFO) on gait patterns in patients with low-level myelomeningocele and to identify any abnormal gait patterns that may lead to future knee instability and pain. A total of 28 children (26 L4-level sides, 18 L5-level sides, and 10 S1-2-level sides) underwent a three-dimensional gait analysis when ambulating barefoot and with AFOs. Results show significant improvements in sagittal plane function with reductions in excessive ankle dorsiflexion, increases in peak plantar flexor moment, and reductions in crouch and knee extensor moment in the L4 and L5 groups. The only improvement in the S1-2 group was a reduction in excessive dorsiflexion, but there was a reduction in power generation at the ankle. The S1-2 group had normal transverse plane knee motion in stance during barefoot walking that increased significantly (p < 0.01) with the AFO. Both the L5 and L4 groups showed greater-than-normal transverse plane knee motion in stance during barefoot walking that also increased significantly (p < 0.01) with the AFO. The results suggest that excessive knee transverse plane rotation may contribute to knee instability more than coronal plane abnormalities. The AFO in S1-2-level patients may be more detrimental for the knee than barefoot walking.

Ankle Joint↗

PubMed2000

MR evaluation of stent patency: in vitro test of 22 metallic stents and the possibility of determining their patency by MR angiography.

RATIONALE AND OBJECTIVES: To determine the extent to which visualization of intrastent anatomy in stents of different composition and design is possible by using contrast-enhanced MR angiography. METHODS: Twenty-two MR-compatible stents, most of which had a diameter of 8 mm, were positioned in a phantom filled with aqueous gadolinium solution. Coronal and axial spoiled three-dimensional gradient-echo sequences were performed. Images were acquired with stents positioned at varying angulations to the main magnetic field B0. Profiles orthogonal to the stent axis allowed measurement of artifact sizes independent of window width and center. RESULTS: Oriented along B0, the Cragg, Corvita, Passager, Wallstent, Strecker, Impag, Perflex, and ZA stents allowed visualization of more than 48% of the lumen. The Memotherm, Smart, and Jostent SelfX stents showed a prominent reduction of the inner lumen to below 41%. The lumina of the covered Jostent, Palmaz, Sinus, and Symphony stents were completely obscured. The Impag, Perflex, and Strecker tantalum stents showed growing artifact sizes and a lumen reduction of at least 40% with increasing angulation to B0. CONCLUSIONS. Evaluation of the inner stent lumen by applying contrast-enhanced, three-dimensional gradient-echo sequences is not possible for the majority of stents because of their large artifacts. These depend on the stent type and orientation to B0. Even stents made of nitinol and cobalt alloys only allow qualitative patency assessment but no quantification of stenosis.

Artifacts↗

PubMedDate not supplied

Three-dimensional echocardiography: the influence of number of component images on accuracy of left ventricular volume quantitation.

One approach to three-dimensional echocardiography is to reconstruct the surface of cardiac structures from two-dimensional images positioned in three-dimensional space. This approach has yielded accurate measures; however, the relationship between the number of nonparallel images used in three-dimensional echocardiographic reconstruction to the accuracy of the volume calculated has not been determined. With a canine model in which instantaneous left ventricular volume could be measured in vivo, images were obtained from intersecting long- and short-axis scans and stored with their spatial coordinates. The left ventricle was reconstructed and its volume calculated. The difference between three-dimensional echocardiographic and true volume was determined in 84 different cavitary volumes (4 to 85 ml). In each case, long- and short-axis images were deleted serially from the original data set (maximum of 27) until there were only three images left in the reconstruction. After each set of deletions, left ventricular volume was recalculated with the remaining images. Three-dimensional echocardiography accurately quantified ventricular volume with eight to 12 intersecting images, with a mean error of less than 1 ml and an SD of 5 ml. With a reduction of component images below eight, there were progressive increases in both absolute and mean percentage error. Accurate assessment of stroke volume and ejection fraction in this beating heart model also required eight to 12 images. Left ventricular volume and systolic function can be quantitated by three-dimensional echocardiography with as few as eight to 12 intersecting or nonparallel images.

Analysis of Variance↗

PubMed2006

Proteomic and bioinformatic analysis of iron- and sulfur-oxidizing Acidithiobacillus ferrooxidans using immobilized pH gradients and mass spectrometry.

A comparative analysis of the protein composition of Acidithiobacillus ferrooxidans cells grown on elemental sulfur and ferrous iron was performed. A newly developed protocol involving immobilized pH gradients, improved protein reduction, mass spectrometry protein identification and full genome sequence information was applied. This approach resulted in more than 1300 protein spots displayed in broad and basic pH ranges, the best A. ferrooxidans proteome resolution to date. A comparative image analysis revealed that the proteome was significantly influenced by the growth type, and allowed for the detection of many physiologically important proteins. Among them were sulfate adenylyltransferase and sulfide dehydrogenase, which are involved in sulfate assimilation and sulfide metabolism, respectively. Many other proteins were related to important processes like cell attachment and electron transport. Co-migration of phosphate and sulfate transport proteins was also observed.

Acidithiobacillus↗

PubMed2001

Invariant manifold methods for metabolic model reduction.

After the decay of transients, the behavior of a set of differential equations modeling a chemical or biochemical system generally rests on a low-dimensional surface which is an invariant manifold of the flow. If an equation for such a manifold can be obtained, the model has effectively been reduced to a smaller system of differential equations. Using perturbation methods, we show that the distinction between rapidly decaying and long-lived (slow) modes has a rigorous basis. We show how equations for attracting invariant (slow) manifolds can be constructed by a geometric approach based on functional equations derived directly from the differential equations. We apply these methods to two simple metabolic models. (c) 2001 American Institute of Physics.

Journal Article↗

PubMed2005

Novel bacterial molybdenum and tungsten enzymes: three-dimensional structure, spectroscopy, and reaction mechanism.

The molybdenum enzymes 4-hydroxybenzoyl-CoA reductase and pyrogallol-phloroglucinol transhydroxylase and the tungsten enzyme acetylene hydratase catalyze reductive dehydroxylation reactions, i.e., transhydroxylation between phenolic residues and the addition of water to a triple bond. Such activities are unusual for this class of enzymes, which carry either a mononuclear Mo or W center. Crystallization and subsequent structural analysis by high-resolution X-ray crystallography has helped to resolve the reaction centers of these enzymes to a degree that allows us to understand the interaction of the enzyme and the respective substrate(s) in detail, and to develop a concept for the respective reaction mechanism, at least in two cases.

Bacteria, Anaerobic↗

PubMed1999

Acute morbidity reduction using 3DCRT for prostate carcinoma: a randomized study.

PURPOSE: To study the effects on gastrointestinal and urological acute morbidity, a randomized toxicity study, comparing conventional and three-dimensional conformal radiotherapy (3DCRT) for prostate carcinoma was performed. To reveal possible volume effects, related to the observed toxicity, dose-volume histograms (DVHs) were used. METHODS AND MATERIALS: From June 1994 to March 1996, 266 patients with prostate carcinoma, stage T1-4N0M0 were enrolled in the study. All patients were treated to a dose of 66 Gy (ICRU), using the same planning procedure, treatment technique, linear accelerator, and portal imaging procedure. However, patients in the conventional treatment arm were treated with rectangular, open fields, whereas conformal radiotherapy was performed with conformally shaped fields using a multileaf collimator. All treatment plans were made with a 3D planning system. The planning target volume (PTV) was defined to be the gross target volume (GTV) + 15 mm. Acute toxicity was evaluated using the EORTC/RTOG morbidity scoring system. RESULTS: Patient and tumor characteristics were equally distributed between both study groups. The maximum toxicity was 57% grade 1 and 26% grade 2 gastrointestinal toxicity; 47% grade 1, 17% grade 2, and 2% grade > 2 urological toxicity. Comparing both study arms, a reduction in gastrointestinal toxicity was observed (32% and 19% grade 2 toxicity for conformal and conventional radiotherapy, respectively; p = 0.02). Further analysis revealed a marked reduction in medication for anal symptoms: this accounts for a large part of the statistical difference in gastrointestinal toxicity (18% vs. 14% [p = ns] grade 2 rectum/sigmoid toxicity and 16% vs. 8% [p < 0.0001] grade 2 anal toxicity for conventional and conformal radiotherapy, respectively). A strong correlation between exposure of the anus and anal toxicity was found, which explained the difference in anal toxicity between both study arms. No difference in urological toxicity between both treatment arms was found, despite a relatively large difference in bladder DVHs. CONCLUSIONS: The reduction in gastrointestinal morbidity was mainly accounted for by reduced toxicity for anal symptoms using 3DCRT. The study did not show a statistically significant reduction in acute rectum/sigmoid and bladder toxicity.

Colon, Sigmoid↗

PubMed2002

The reliability of approximate reduction techniques in population models with two time scales.

As a result of the complexity inherent in some natural systems, mathematical models employed in ecology are often governed by a large number of variables. For instance, in the study of population dynamics we often find multiregional models for structured populations in which individuals are classified regarding their age and their spatial location. Dealing with such structured populations leads to high dimensional models. Moreover, in many instances the dynamics of the system is controlled by processes whose time scales are very different from each other. For example, in multiregional models migration is often a fast process in comparison to the growth of the population. Approximate reduction techniques take advantage of the presence of different time scales in a system to introduce approximations that allow one to transform the original system into a simpler low dimensional system. In this way, the dynamics of the original system can be approximated in terms of that of the reduced system. This work deals with the study of that approximation. In particular, we work with a non-autonomous discrete time model previously presented in the literature and obtain different bounds for the error we incur when we describe the dynamics of the original system in terms of the reduced one. The results are illustrated by some numerical simulations corresponding to the reduction of a Leslie type model for a population structured in two age classes and living in a two patch system.

Animals↗

PubMed1977

The sialoglycoprotein subunits of human placental brush border membranes characterized by two-two-dimensional electrophoresis.

A brush border membrane enriched fraction was isolated from human full-term placenta. This membrane fraction exhibited large membrane fragments with microvilli projecting from the basal membrane in electron micrographs and was enriched tenfold in alkaline phosphatase, a brush border enzyme marker. The sialoglycoproteins associated with this membrane fraction were tritiated by mild periodate oxidation of sialic acid and reduction with tritiated NaBH4. The membranes were solubilized in 8 M urea, 2 percent Triton X-100, and the tritiated glycoprotein subunits were reduced with beta-mercaptoethanol and characterized by 2-dimensional poly-acrylamide gel electrophoresis using a method similar to that described by O'Farrell and Bhakdi, Knüferman, and Wallach. The tritiated subunits were detected in the gels by autofluorography. The 2-dimensional subunit "maps" resolved at least 17 major sialoglycoprotein subunits whereas only 10 major periodate-Schiff reagent staining components were resolved by 1-dimensional SDS polyacrylamide gel electrophoresis. Placental alkaline phosphatase (PAP) was identified on the subunit maps by inclusion of 32P-labeled PAP in the tritiated membrane sample. The 32P-labeled PAP corresponded to a major tritiated sialoglycoprotein subunit, which was heterogeneous with respect to charge as demonstrated by 3 closely running spots of the same molecular weight.

Cell Fractionation↗

PubMed2026

Toxicoproteomic analysis reveals arsenic-induced alterations in eye lens proteins of Labeo rohita.

Arsenic occurs extensively in the environment and is classified as a potent carcinogenic substance in humans. Prolonged intake of water contaminated with arsenic results in the development of arsenicosis. In the present study, a toxicoproteomic approach was employed to elucidate arsenic-induced alterations in lens proteins using a fish model. Juveniles of Labeo rohita were exposed to sodium meta-arsenite (NaAsO2) at concentrations of 5, 10, 15, and 20 ppm for a period of 10 days in triplicate experimental groups. Soluble lens proteins were analyzed using one- and two-dimensional gel electrophoresis, immunoblotting of αA-crystallin and MALDI-TOF mass spectrometry. Cataract development was observed at arsenic concentrations ≥ 15 ppm. Proteomic analyses revealed concentration-dependent alterations in lens protein abundance, including significant reductions in βB1, βB2, and βA2b-crystallin, small heat shock protein and skeletal α-actin (p < 0.05). In addition, αA, βA2, and βA2a-crystallin exhibited reduced abundance trends, although these changes were not statistically significant. Two-dimensional immunoblotting revealed 15 distinct αA-crystallin isoforms in control lenses, several of which showed a progressive decrease with increasing arsenic exposure, culminating in complete degradation at 20 ppm. These findings demonstrate that arsenic exposure is associated with substantial alterations in lens crystallins and other proteins involved in structural organization and protein homeostasis, coinciding with cataract development at higher exposure concentrations. The identified proteins may serve as potential toxicoproteomic biomarkers of lens damage in aquatic organisms and provide a foundation for future studies investigating the molecular mechanisms of arsenic-induced lens toxicity.

Animals↗

PubMed2003

Finite element modeling of trabecular bone damage.

This paper presents a finite element-based, computational model for analysis of structural damage to trabecular bone tissues. A modulus reduction method was formulated from elasto-plasticity theory, and was used to account for site-specific trabecular bone tissue damage. Trabecular bone tissue damage is illustrated using a large-scale, anatomically accurate, two-dimensional, microstructural finite element model of a human thoracic vertebral body. Four models with varying specifications for damage accumulation were subjected to compressive loading and unloading cycles. The numerical results and experimental validation demonstrated that the modulus reduction method reproduced the non-linear mechanical behaviour of vertebal trabecular bone. The iterative computational approach presented provides a methodology to study trabecular bone damage, and should provide researchers with a computational approach to study bone fracture and repair and to predict vertebral fragility.

Aged↗

PubMed2002

Shear-induced stress relaxation in a two-dimensional wet foam.

We report on experimental measurements of the flow behavior of a wet, two-dimensional foam under conditions of slow, steady shear. The initial response of the foam is elastic. Above the yield strain, the foam begins to flow. The flow consists of irregular intervals of elastic stretch followed by sudden reductions of the stress, i.e., stress drops. We report on the distribution of the stress drops as a function of the applied shear rate. We also comment on our results in the context of various two-dimensional models of foams.

Journal Article↗

PubMed2003

[Eletrocatalytic oxidation for organic pollutant on the nanoparticle platinum coated titanium electrode].

The nanoparticle platinum coated titanium electrode was prepared using the method of electrochemical cathodic reduction followed by anodic oxidation. The surface microstructure of electrode has demonstrated that platinum particles dispersed in the three-dimensional network of channels of the titanium oxide film were in the supper-fine and well-distributed state. The nanoparticle platinum electrode owned plenty of active points and well electrocatalytic property based on the exposed platinum particles with very small diameters. Electrochemical behaviors of two kinds of platinum electrode for methanol has been performed through Cyclic Voltammetry. The results have showed that the nanoparticle platinum electrode had a much better electrocatalytic property for methanol than smooth platinum electrode in acidic, neutral or alkaline medium. The oxidation current densities on nanoparticle platinum electrode are over 100 times of that on smooth platinum electrode. Furthermore, the values of average current efficiency on nanoparticle platinum electrode are several times of that on smooth platinum electrode when degrading three kinds of organics methanol, phenol and methyl orange. This clearly revealed that the nanoparticle platinum electrode had stronger ability to degrade organic pollutants.

Catalysis↗

PubMed2001

Segmental cardiac function computed from ECG-gated SPECT images through solution of equations of continuity for fluids.

Segmental contractions were quantified from images of electrocardiographic-gated single-photon emission computed tomography. Counts were integrated in 64 angles about the centre on short-axis images and projected onto a cylindrical screen. Changes in the projected count were shown to obey the equation of continuity for two-dimensional fluids (the Poisson equation). Displacements of each pixel point were calculated from the velocity field to quantify the amount of dislocation. Changes in the configuration of the pixel points were projected back on the cardiac wall, and finally segmental contractions were evaluated as a percentage reduction of the area. Computer simulations were performed for numerical models of circumferential and long-axial contractions, uneven eccentric contractions and rotations. These models were blurred with a three-dimensional Gaussian function. The results obtained using this method (quantification of segmental function by solving the Poisson equation (QSFP)) were compared with the wall-thickening method (WTM) and the maximum-count method. Both QSFP and WTM yielded good agreement with predicted values for circumferential and long-axial contractions. Only QSFP gave satisfactory results for uneven eccentric contractions, and rotation models. QSFP should provide a useful tool for in vivo quantification of contraction tangential to the cardiac wall by eliminating errors due to displacements.

Aged↗