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Volume Distribution (volume + distribution)
Selected Abstracts99mTc-MIBI imaging for prediction of therapeutic effects of second-generation MDR1 inhibitors in malignant brain tumorsINTERNATIONAL JOURNAL OF CANCER, Issue 12 2007Toshio Sasajima Abstract The aim of this study was to explore whether 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) is suitable to elucidate multidrug resistance and prediction of potentiation of antitumor agents by second-generation MDR1 inhibitors (PSC833, MS-209) in malignant brain tumors in rat. Malignant tumor cells (RG2 and C6 gliomas, Walker 256 carcinoma) were incubated with low dose vincristine (VCR) to induce multidrug resistance. MTT assay demonstrated a significant increase of surviving fractions in VCR-resistant sublines compared to those of drug-naive cells. Reverse transcriptase polymerase chain reaction revealed higher expression of MDR1 mRNA in VCR-resistant cells than drug-naive cells in each line. Volume distribution (Vd) of 99mTc-MIBI was negatively correlated with MDR1 mRNA expression among drug-naive and VCR-resistant cells. MDR1 inhibitors decreased surviving fractions and increased Vd of 99mTc-MIBI significantly in VCR-resistant sublines, whereas MDR1 mRNA expression was unchanged. These findings indicate that 99mTc-MIBI efflux was functionally suppressed by MDR1 inhibitors. Autoradiographic images of 99mTc-MIBI revealed higher uptake in drug-naive cells at basal ganglia compared with VCR-resistant cells at the opposite basal ganglia of rats. Oral administration of the second-generation MDR1 inhibitors significantly increased 99mTc-MIBI accumulation of both tumors. Therapeutic effects of VCR with or without the MDR1 inhibitors were also evaluated autoradiographically using 14C-methyl- L -methionine (14C-Met) and MIB-5 index. 14C-Met uptake and MIB-5 index of both tumors treated with VCR following the MDR1 inhibitor treatment significantly decreased compared with tumors treated with VCR alone. Analysis of 99mTc-MIBI accumulation is considered informative for detecting MDR1-mediated drug resistance and for monitoring the therapeutic effects of MDR1 inhibitors in malignant brain tumors. © 2007 Wiley-Liss, Inc. [source] Urinary tract cancer screening through analysis of urinary red blood cell volume distributionINTERNATIONAL JOURNAL OF UROLOGY, Issue 7 2000Mamoru Wakui Abstract Background: Hematuria is differentiated between glomerular and urinary tract origins on the basis of urinary red cell morphology. We used this distinction in a program of mass screening for urinary tract cancer to achieve cost-effective and safe hematuria screening. Methods: Of a total of 21 372 adults (mean age 52.3 years; range 20,79 years) participating in a health screening, 912 (4.3%) had a positive dipstick for hematuria and were enrolled in the present study. Urinary red cell volume distribution curves (RDC), the simplest method of assessing urinary red cell morphology, were calculated and subjects were divided into two groups based on their RDC patterns. Group I subjects had a normocytic or mixed pattern and they were immediately investigated for urinary tract malignancy because of the associated risk for urological disease. Group II subjects had a microcytic pattern and, therefore, were judged to be at a low risk of urologic malignancy and were followed up 3 years later without urologic investigations. Results: Among the 38 subjects in group I (4% of all dipstick-positive subjects), one case of bladder cancer was detected. In the remaining 37 patients, 15 cases of benign diseases were discovered. Group II was composed of 869 subjects (96%). The inquiry into their health status conducted 3 years later revealed that 831 (95.6%) were healthy and, of these, 13 had experienced gross hematuria during the period but urological malignancies were ruled out by their urologists, two (0.2%) had died of diseases other than urological cancer and 36 (4.1%) were lost to follow-up. With our method, total costs have been reduced by 93.8% against a conventional setting of a full evaluation for all cases of hematuria. Conclusions: Microcytic hematuria, accounting for 96% of asymptomatic microhematuria cases in the present study, was not associated with a risk for urinary tract malignancy. Compared with conventional hematuria screening with a complete work-up of all cases of hematuria, investigating only subjects with mixed or normocytic RDC patterns was safe and cost effective. [source] Structure of nanoporous zirconia-based powders synthesized by different gel-combustion routesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007Jorge R. Casanova Zirconia-based ceramics that retain their metastable tetragonal phase at room temperature are widely studied due to their excellent mechanical and electrical properties. When these materials are prepared from precursor nanopowders with high specific surface areas, this phase is retained in dense ceramic bodies. In this work, we present a morphological study of nanocrystalline ZrO2,2.8 mol% Y2O3 powders synthesized by the gel-combustion method, using different organic fuels , alanine, glycine, lysine and citric acid , and calcined at temperatures ranging from 873 to 1173,K. The nanopore structures were investigated by small-angle X-ray scattering. The experimental results indicate that nanopores in samples prepared with alanine, glycine and lysine have an essentially single-mode volume distribution for calcination temperatures up to 1073,K, while those calcined at 1173,K exhibit a more complex and wider volume distribution. The volume-weighted average of the nanopore radii monotonically increases with increasing calcination temperature. The samples prepared with citric acid exhibit a size distribution much wider than the others. The Brunauer,Emmett,Teller technique was used to determine specific surface area and X-ray diffraction, environmental scanning electron microscopy and transmission electron microscopy were also employed for a complete characterization of the samples. [source] Impact of H+ ion beam irradiation on Matrimid®.JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Abstract Ion beam irradiation is an easily controlled method to modify the chemical structure and microstructure of polymers including the fractional free volume, free volume distribution and chain mobility, thus altering the gas transport properties of the irradiated polymers. The previous paper focused on the impact of H+ ion beam irradiation on chemical structural evolution of the polyimide Matrimid®. This paper focuses on the impact of H+ ion beam irradiation on microstructure and gas permeation properties of Matrimid®. Irradiation at low ion fluence resulted in slight decreases in permeabilities for five gases (i.e., He, CO2, O2, N2, and CH4) with increases in permselectivities for some gas pairs (e.g., He/CH4 and He/N2). In contrast, irradiation at relatively high ion fluences resulted in simultaneous increases in permeabilities and permselectivities for most gas pairs (e.g., He/CH4, He/N2, O2/N2, and CO2/CH4). While Matrimid® has bulk gas permeation properties that are below the range of commercially interesting polymers, samples irradiated at high ion fluences exhibited significant improvement in gas separation performances. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1670,1680, 2007 [source] Effect of hemodialysis on the plasma levels of clofarabine,,PEDIATRIC BLOOD & CANCER, Issue 1 2010Peter G. Steinherz MD Abstract Clofarabine, a nucleoside analogue for treatment of relapsed leukemia, is 50,60% excreted in urine. Clofarabine has not been studied in patients on hemodialysis. We measured levels in one patient in acute renal failure. Prior to dialysis, 43,hr after a 40,mg/m2 infusion, plasma concentration was 139,ng/ml. One hour after begining hemodialysis, a 20,mg/m2 infusion began. Plasma concentrations were 84.2, 81.1, and 88.0,ng/ml while the dialysis and clofarabine infusion occurred simultaneously. Post-dialysis, while the clofarabine was still infusing, the level was 95.8,ng/ml. Hemodialysis does decrease clofarabine levels, but given its large volume distribution, hemodialysis may not be effective for clofarabine overdose. Pediatr Blood Cancer 2010;55:196,198. © 2010 Wiley-Liss, Inc. [source] Genetic effects of the soft starch (h) and background loci on volume of starch granules in five inbreds of maizePLANT BREEDING, Issue 2 2000J. A. Wilson Abstract Larger particle volume is beneficial for many aspects of maize starch processing, and may improve the performance of some starch attributes. This study focused on the soft starch (h) locus to identify its potentially influential role in starch particle volume distribution. The objectives were to study the genetic expression of starch particle volume of the h locus in different genetic backgrounds and the gene action conditioning starch particle volume of other loci in both normal-starch and h -starch backgrounds. Forty-five populations (five intra-inbred F1s, 10 hybrid F1s 10 F2s, 10 BC1F1s to h/h parent, and 10 BC1 to h:h conversion of normal parent) were planted in 1993 at two locations and in 1995 at one location. Selfed heterozygotes (±/h) in all generations provided intra-ear comparisons of normal and h starch, and F3 and BC1F2 generations provided inter-ear comparisons. Significant differences were found between normal and h:h genotypes in all intra-ear and inter-ear comparisons. In all cases, general combining ability effects were highly significant, suggesting the presence of additive gene effects. Generation mean analysis of normal and h:h starch materials yielded similar results, indicating the predominance of additive and some dominance effects for other loci on starch particle volume. These results indicate the usefulness of the soft starch gene and additional genetic variation among inbreds in the improvement of starch particle volume for increased starch recovery in wet milling. [source] Polycarbonate/SiC nanocomposites,influence of nanoparticle dispersion on molecular mobility and gas transport,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2-3 2005Martin Böhning Abstract Plasma synthesized silicon carbide (SiC) nanoparticles were dispersed in dichloromethane/poly(bisphenol-A-carbonate) (PC) solutions by high power ultrasonification. Samples were then prepared by film casting under well adapted preparation conditions. The influence of the SiC nanoparticles on the molecular mobility of the PC is studied by dielectric relaxation spectroscopy. No effect on the cooperative segmental mobility (glass transition) was detected. But the relaxation region corresponding to localized fluctuations is strongly broadened and the activation energy is reduced with increasing nanoparticle concentration. The most significant change was observed in the relaxation region between , - and , -process. The gas transport properties of these nanocomposite films are characterized in terms of permeability, diffusivity and solubility. Results can be interpreted based on an altered local free volume distribution and a change of molecular mobility of the polymer matrix near the nanoparticle surface which is in agreement with the dielectric results. Concentration dependent CO2 permeation experiments reveal a significant reduction of plasticization effects in the nanocomposites compared to the pure PC. Copyright © 2005 John Wiley & Sons, Ltd. [source] Stochastic Morphometric Model of the Balb/c Mouse LungTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 10 2010Pierre Madl Abstract The laboratory mouse is often used as a human surrogate in aerosol inhalation studies. Morphometric data on the tracheobronchial geometry of three in situ lung casts of the Balb/c mouse lung produced by the Air Pollution Health Effects Laboratory were analyzed in terms of probability density functions and correlations among the different airway parameters. The results of this statistical analysis reveal significant differences in diameters and branching angles between major and minor progeny branching off from the same parent airway at a given airway bifurcation. Number of bronchial airways generations along a given path, expressed by the termination probability, branching angles, and daughter-to-parent diameter ratios indicate that the location of an airway with defined linear airway dimensions within the lung is more appropriately identified by its diameter (or its parent diameter) than by an assigned generation number. We, therefore, recommend classifying the mouse lung airways by their diameters and not by generation numbers, consistent with our previous analysis of the rather monopodial structure of the rat lung (Koblinger et al., J Aerosol Med 1995;8:7,19; Koblinger and Hofmann, J Aerosol Med 1995;8:21,32). Because of lack of corresponding information on respiratory airways, a partly stochastic symmetric acinar airway model was attached to the tracheobronchial model, in which the number of acinar airways along a given path was randomly selected from a measured acinar volume distribution. The computed distributions of the geometric airway parameters and their correlations will be used for random pathway selection of inhaled particles in subsequent Monte Carlo deposition calculations. Anat Rec 293:1766,1786, 2010. © 2010 Wiley-Liss, Inc. [source] Cover Picture: Colloidal Synthesis of Hollow Cobalt Sulfide Nanocrystals (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 11 2006Mater. Abstract Hollow nanocrystals have been synthesized through a mechanism analogous to the Kirkendall Effect. When a cobalt nanocrystal reacts with sulfur in solution, the outward diffusion of cobalt atoms is faster than the inward diffusion of sulfur atoms through the sulfide shell. The dominating outward diffusion of cobalt cations produces vacancies that can condense into a single void in the center of the nanocrystal at high temperatures. This process provides a general route to the synthesis of hollow nanostructures of a large number of compounds and is described in the Full Paper by A.,P. Alivisatos and co-workers on p.,1389. Formation of cobalt sulfide hollow nanocrystals through a mechanism similar to the Kirkendall Effect has been investigated in detail. It is found that performing the reaction at >,120,°C leads to fast formation of a single void inside each shell, whereas at room temperature multiple voids are formed within each shell, which can be attributed to strongly temperature-dependent diffusivities for vacancies. The void formation process is dominated by outward diffusion of cobalt cations; still, the occurrence of significant inward transport of sulfur anions can be inferred as the final voids are smaller in diameter than the original cobalt nanocrystals. Comparison of volume distributions for initial and final nanostructures indicates excess apparent volume in shells, implying significant porosity and/or a defective structure. Indirect evidence for fracture of shells during growth at lower temperatures was observed in shell-size statistics and transmission electron microscopy images of as-grown shells. An idealized model of the diffusional process imposes two minimal requirements on material parameters for shell growth to be obtainable within a specific synthetic system. [source] A new method for three-dimensional skeleton graph analysis of porous media: application to trabecular bone microarchitectureJOURNAL OF MICROSCOPY, Issue 2 2000L. Pothuaud This paper introduces a new three-dimensional analysis of complex disordered porous media. Skeleton graph analysis is described and applied to trabecular bone images obtained by high resolution magnetic resonance imaging. This technique was developed bearing in mind topological considerations. The correspondence between vertices and branches of the skeleton graph and trabeculae is used in order to get local information on trabecular bone microarchitecture. In addition to real topological parameters, local structural information about trabeculae, such as length and volume distributions, are obtained. This method is applied to two sets of samples: six osteoporosis and six osteoarthritis bone samples. We demonstrate that skeleton graph analysis is a powerful technique to describe trabecular bone microarchitecture. [source] Combinatorial development of polymer nanocomposites using transient processing conditions in twin screw extrusionAICHE JOURNAL, Issue 7 2008Arun K. Kota Abstract A new approach is presented for combinatorial development of polymer nanocomposites with compositional gradients (CGs). The CGs were developed using transient processing conditions in twin screw extrusion with small quantities of expensive nanoscale fillers. Convolution of step input with normalized residence volume distributions (RVDs) was used to establish the processing,structure relationship for the CGs. The normalized RVD was established as a process characteristic independent of processing conditions and measured in situ using an optical probe. The CG determined nondestructively using the new combinatorial approach was validated through comparison with more time-consuming and destructive thermogravimetric analysis. The CG could also be established with relatively inexpensive microscale fillers using the normalized RVD obtained with nanoscale fillers, suggesting that transient effects of the mixing process are independent of the size of the filler. Finally, structure,property relationship of combinatorially developed polymer nanocomposites was established by characterizing their dynamic mechanical behavior (storage modulus, G,, and loss modulus, G,). The dynamic mechanical behavior of the combinatorially developed composites correlated well with the batch-processed ones, indicating that the transient mixing conditions in extrusion do not affect the material properties. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Methane hydrate equilibria in silica gels with broad pore-size distributionsAICHE JOURNAL, Issue 2 2002Duane H. Smith Equilibrium pressures for the dissociation of methane hydrates confined in silica gel pores of nominal radii 7.5, 5.0 and 3.0 nm were measured over a wide temperature range, and were observed to be higher than those for bulk methane hydrate. A model is presented that allows the pore radius involved in each equilibrium to be determined from these data, so that the model exactly reproduces the experimental equilibrium pressure. Based on this model, pore volume distributions were reconstructed and found to be in good agreement with those obtained from nitrogen desorption isotherms, indicating that hydrate formed nearly uniformly in the available pores. [source] Local residence time, residence revolution, and residence volume distributions in twin-screw extrudersPOLYMER ENGINEERING & SCIENCE, Issue 1 2008Xian-Ming Zhang This work was aimed at studying the overall, partial, and local residence time distributions (RTD); overall, partial and local residence revolution distributions (RRD) and overall, partial and local residence volume distributions (RVD) in a co-rotating twin screw extruder, on the one hand; and establishing the relationships among them, on the other hand. Emphasis was placed on the effects of the type and geometry of mixing elements (a gear block and various types of kneading elements differing in staggering angle) and process parameters on the RTD, RRD and RVD. The overall and partial RTD were directly measured in-line during the extrusion process and the local ones were calculated by deconvolution based on a statistical theory. The local RTD allowed comparing the mixing performance of mixing elements. Also it was confirmed both experimentally and theoretically that specific throughput, defined as a ratio of throughput (Q) over screw speed (N), controlled all the above three types of residence distributions, be they local, partial or overall. The RRD and RVD do not provide more information on an extrusion process than the corresponding RTD. Rather they are different ways of representing the same phenomena. POLYM. ENG. SCI., 48:19,28, 2008. © 2007 Society of Plastics Engineers [source] Cell Subpopulation-related Volumetric Parameters: a Complementary Tool of the Modified Hypo-osmotic Swelling Test on Model of Boar SpermatozoaREPRODUCTION IN DOMESTIC ANIMALS, Issue 5 2000A. Petrounkina Content It is a general property of the intact animal cell to swell rapidly in response to hypo-osmotic conditions. The modified hypo-osmotic swelling test (HOS-test) is an indicative test to evaluate the integrity of the plasma membrane by means of an electronic cell counter, based on the relative increase of the cell volume in response to hypo-osmotic conditions. In this study the relationships between the osmotically induced changes of the cell volume of boar spermatozoa as determined by cell counter and the integrity of the membrane as determined by propidium iodide staining (PI) were studied. Boar sperm cell volume distributions were measured under iso-osmotic (300 mosmolar) conditions and after a hypo-osmotic stress (150 mosmolar). The relative volume shift of mean and modal volume were calculated as a proportion coefficient of modal and mean values of the cell volume distributions by transition from iso-osmotic to hypo-osmotic conditions. The volumetric parameters related to the different cell subpopulations were derived from the different peaks of cell volume distributions. PI-staining techniques were used for comparison. The values of the volume shift and of derived percentages of the osmotically inactive cells were correlated negatively and positively, respectively (p < 0.05) with the percentage of the PI-stained cells. This correlation indicates that a relationship exists between membrane functions of the different cell compartments (sperm head and tail) due to the circumstance that the increase of the cell volume in the HOS-test is associated with the morphological changes in the tail and the PI-staining is associated with the membrane integrity and permeability of the head region. The advantage of computer-assisted volume measurement is that a large number of cells (5000,50 000 spermatozoa) can be measured and evaluated during one procedure and in a very short time. The relative volume shift is a quantitative continuous parameter characterizing the osmotic reactivity and membrane functional competence of a cell population and of subpopulations within one ejaculate. This parameter could be useful to evaluate membrane functional competence rapidly and sensitively. Inhalt Es ist eine generelle Eigenschaft membranintakter tierischer Zellen, mit einer Volumenzunahme auf eine hypoosmotische Belastung zu reagieren. Der auf der relativen Vergrößierungdes Zellvolumens basierende modifizierte hypoosmotischeSchwelltest ist ein indikativer Test zur Beurteilung der Membranintegrität mittels eines elektronischen Partikelzählers. In dieser Studie wurden die Zusammenhänge zwischen der mittels der Propidiumjodid-Färbung bestimmten Zellmembranintegrität und den osmotisch induzierten Veränderungen des Zellvolumens von Eberspermien untersucht. Volumenverteilungen von Eberspermien wurden unter isoosmotischen (300 mosmolar) und hypoosmotischen (150 mosmolar) Bedingungen gemessen. Die relative Volumenverschiebung der modalen und mittleren Werte der Volumenverteilung wurde als Quotient aus Modalwerten der Zellvolumenverteilungen und des mittleren Zellvolumens beim Übergang von isotonen zu hypotonen Bedingungen berechnet. Die auf verschiedene Subpopulationen bezogenen volumetrischen Parameter werden aus den originalen Volumenverteilungen berechnet. Der Betrag der Zellvolumenzunahme und die aus den Volumenverteilungen bestimmten Anteile an Zellen mit beschädigter Geißielmembran korrelierten signifikant negativ bzw. positiv (p < 0,05) mit dem Anteil an den Zellen mit beschädigter Kopfmembran, der sich aus der Propidiumjodid-Färbung ergab. Es wird geschlossen, daßi im Verhalten zwischen den Membranen der verschiedenen Zellkompartimente (Spermienkopf und-Geißiel) ein Zusammenhang besteht. Die beschriebene Methode ermöglicht die Analyse großier Zellpopulationen (5.000,50.000 Zellen). Die relative Volumenverschiebung stellt einen quantitativen kontinuierlichen Parameter dar, der den Membranzustand der Eberspermien einer Spermatozoenpopulation und Subpopulationen innerhalb eines Ejakulates charakterisiert. Diese Parameter können zur schnellen und sensitiven Beurteilung der Membranzustandes eingesetzt werden. [source] | |||||||||||||||||||