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PubMed1999

Modeling of Random Formation of Microporous Material Following Thermodynamic Limitations.

The problem of pore formation in limited (small) volume has been considered. General equations describing the system in the continuous (many particles) and discrete (few particles) cases have been obtained. It has been shown that pore formation is not limited by nucleus genesis because of entropic reasons. Kinetic limitation leads to the auto-acceleration-like form of the dependence of the number of empty cells and the internal area functions. The percolation problem has been solved for 2- and 3-dimensional cases with comparison of systems obtained by traditional Monte Carlo and thermodynamic factors. The 3-dimensional situation leads to reduction of the percolation threshold. However, the difference in the values of percolation thresholds estimated by the ordinary Monte Carlo simulation and with thermodynamic limitation is not significant (less than the eventual error). The change of tortuosity was estimated. At the percolation threshold, the tortuosity decreases rapidly, then very slowly with an increase in microporosity, and only at very high microporosity (close to 1) the decrease in tortuosity is again sharp. The influence of the thermodynamic limitation on the regularity of the micropore cluster has been analyzed based on the consideration of behavior of free energy and surface area of the cluster. It has been found that both of these structural parameters significantly decrease if the thermodynamic limitation is imposed. Copyright 1999 Academic Press.

Journal Article↗
PubMed2006

An extended index to quantify normality of gait in children.

Clinical gait analysis aims to quantify and assess the mechanics of walking and identify deviations from 'normal' movement patterns. To facilitate the use of clinical equipment, protocols are required to process data and produce a few meaningful summary measurements which can, in turn, be used to flag gait abnormalities. Earlier work produced a one-dimensional index of gait, calculated from sagittal hip, knee and ankle rotation angle patterns. The objective of this study was to extend the original index, incorporating kinematic and kinetic data from multiple planes, while allowing for correlations between component measures. A one-dimensional index of normal gait was developed, based on normative gait data (N=45 children, aged 3-13 years). The new one-dimensional index was calculated using correlation patterns between seven component indices, each of which has diagnostic interpretation. The effectiveness of the new index was tested using immature normative data (N=14) and hypotonic data (N=10). Approximately 85% of immature normative children and 100% of hypotonic children were classified as either unusual or extreme by the one-dimensional index. These data reduction protocols improve objective gait analyses in the clinical setting.

Adolescent↗
PubMed2003

A method for monitoring the surface conservation of wooden objects by Raman spectroscopy and multivariate control charts.

The principles of quality control and multivariate statistical analysis were applied to the monitoring of the conservation state of wooden works of art. Three degradation processes (exposure to a wet atmosphere, to an acidic attack, and to UV light) were simulated on the surface of wooden boards of the XVI century and were monitored by the use of Raman spectroscopy. The resulting spectra were treated by principal component analysis, which allowed reduction of the system dimensionality. The relevant principal components were used to build multivariate control charts, namely, the Shewhart, CUSUM, and SMART (simultaneous scores monitoring and residual tracking) control charts. The Shewhart charts allowed identification of the effects due to the degradation processes. The CUSUM charts permitted identifcation of the exact moment in which the degradation treatment was started. The SMART charts provided a synthetic description of the conservation state of the wooden surface by means of only two charts: the T2 Hotelling and the DModX charts.

Journal Article↗
PubMed2000

Orientation of iron bleomycin and porphyrin complexes on DNA fibers.

Bleomycin (Blm) is an antitumor agent that requires iron and oxygen for strand cleavage of DNA. In this study, ferric bleomycin, Fe(III)Blm, or the nitric oxide adduct of ferrous bleomycin, ON-Fe(II)Blm, were bound to one-dimensionally oriented DNA fibers. Reductive nitrosylation of Fe(III) complexes took place in situ on B-form DNA fibers. Electron paramagnetic resonance (EPR) spectra were obtained as a function of the angle phi between the magnetic field B and the fiber axis Zf. For comparison, EPR spectra were acquired for ON-Fe(II)TMpyP and ON-Fe(II)TMpyP-Im on oriented DNA fibers, where TMpyP is 5,10,15,20-tetrakis(1-methyl-4-pyridino)porphyrin and Im is imidazole. EPR spectra showed both low-spin Fe(III)Blm and ON-Fe(II)Blm bound to B-form DNA in two slightly different binding orientations in the ratio of 1:0.2. With A-form DNA, a fraction of bound Fe(III)Blm was high spin. Specifically, the angle beta between the fiber axis Zf and the g axis, gz, perpendicular to or nearly perpendicular to the equatorial plane of the iron complex was estimated as 20 degrees and 25 degrees for ON-Fe(II)Blm and 30 degrees and 25 degrees for Fe(III)Blm, respectively. The angle gamma that determines the orientation of gx and gy axes was estimated as 90 degrees for the two ON-Fe(II)Blm species and 10 degrees for the two Fe(III)Blm species, respectively. The NO was held rigidly in place as the temperature increased from 123 K to room temperature for ON-Fe(II)Blm but not for ON-Fe(II)TMpyP or ON-Fe(II)TMpyP-Im. It is hypothesized that the NO is structurally oriented by hydrogen bonding like the peroxide is held in HO2(-)-Co(III)Blm (Wu et al. J. Am. Chem. Soc. 1996, 118, 1281-1294). The EPR parameters are consistent with a six-coordinate complex for ON-Fe(II)Blm, although the superhyperfine structure from the trans nitrogen was not detected. The increase in g value anisotropy upon binding ON-Fe(II)Blm to DNA fiber may be caused by an increase in the overlap of d pi and 2p pi* orbitals induced by an interaction of NO with DNA and/or by a perturbation of d orbitals due to the pyrimidine-guanine interaction. It is concluded that the EPR parameters of ON-Fe(II)Blm and Fe(III)Blm bound to oriented DNA support the hypothesis that FeBlm species bind to DNA with adduct structures similar to those formed by related CoBlm species and DNA.

Animals↗
PubMed2002

Modelling normal tissue isoeffect distribution in conformal radiotherapy of glioblastoma provides an alternative dose escalation pattern through hypofractionation without reducing the total dose.

The purpose of this study was to prove that by using conformal external beam radiotherapy (RT) normal brain structures can be protected even when applying an alternative approach of biological dose escalation: hypofractionation (HOF) without total dose reduction (TDR). Traditional 2-dimensional (2D) and conformal 3-dimensional (3D) treatment plans were prepared for 10 gliomas representing the subanatomical sites of the supratentorial brain. Isoeffect distributions were generated by the biologically effective dose (BED) formula to analyse the effect of conventionally fractionated (CF) and HOF schedules on both the spatial biological dose distribution and biological dose-volume histograms. A comparison was made between 2D-CF (2.0 Gy/day) and 3D-HOF (2.5 Gy/day) regimens, applying the same 60 Gy total doses. Integral biologically effective dose (IBED) and volumes received biologically equivalent to a dose of 54 Gy or more (V-BED54) were calculated for the lower and upper brain stem as organs of risk. The IBED values were lower with the 3D-HOF than with the 2D-CF schedule in each tumour location, means 22.7+/-17.1 and 40.4+/-16.9 in Gy, respectively (p < 0.0001). The V-BED54 values were also smaller or equal in 90% of the cases favouring the 3D-HOF scheme. The means were 2.7+/-4.8 ccm for 3D-HOF and 10.7+/-12.7 ccm for 2D-CF (p = 0.0006). Our results suggest that with conformal RT, fraction size can gradually be increased. HOF radiotherapy regimens without TDR shorten the treatment time and seem to be an alternative way of dose escalation in the treatment of glioblastoma.

Brain↗
PubMed1997

Time-resolved X-ray powder diffraction using a large-area CCD-based detector and Rietveld refinement: solid-state polymerization of S2N2 to (SN)x.

A kinetic study of the solid-state polymerization of disulfur dinitride (S2N2) to polysulfur nitride [(SN)x] has been performed, combining monochromatic high-energy (lambda = 0.3263 A) synchrotron radiation X-ray powder diffraction, a large-area (ø = 220 mm) CCD-based X-ray image-intensifier detector and Rietveld refinement. Recently developed techniques for detector calibration and reduction of two-dimensional images to one-dimensional diffraction patterns have been employed for data processing/analysis. Good fits were obtained after Rietveld refinement [Rp = 8.4%, wRp = 9.4%, sin(theta(max))/lambda = 0.585 A(-1)] of diffraction patterns of S2N2 from images with 2 s exposure time. The solid-state polymerization of S2N2 to (SN)x, was followed at a maximum rate of two diffraction images per minute. Scale factors and cell parameters for S2N2 and beta-(SN), as functions of time were readily obtained after Rietveld refinement of the diffraction patterns obtained from each individual image throughout the polymerization. The polymerization was preceded by a lattice distortion of S2N2, and at 50% conversion the a axis had decreased by about 1% and the c axis had increased about 1%. The polymerization yielded not only the expected polymer beta-(SN)x, but also a small amount of a compound that could be another phase of (SN)x.

Journal Article↗
PubMed1981

Glutathione reductase from human erythrocytes: amino-acid sequence of the structurally known FAD-binding domain.

Glutathione reductase (Mr 2 x 52 500), a flavoenzyme of known three-dimensional structure, catalyses the reduction of glutathione disulfide by NADPH. This paper describes the primary structure of the FAD-binding domain which ranges from AcAla-1 to Gly-157. The three CNBr-produced fragments (69, 10 and 80 residues) of the domain were fractionated further by enzymatic and chemical methods; isolated peptides were sequenced mainly by automatic solid-phase Edman degradation. The tryptic peptides were overlapped by chymotryptic peptides. A fragment which results from cleavage at the acid-labile bond between Asp-135 and Pro-136 supplied peptides for overlapping the CNBr-produced fragments. In addition, many peptides were ordered and overlapped by computerized comparison with a complete sequence guessed from the electron density map. With one exception the computer method and the chemical alignment gave the same results. The sequence data are discussed in the light of the secondary and tertiary structure (Schulz et al. (1978) Nature (Lond.) 273, 120--124]. The 17 N-terminal residues are not visible in the electron density map. Consequently our numbering scheme differs from that of Schulz et al. by approximately 20 residues. Acetylation of the N terminus and an unusual composition of the following residues may serve to protect the loose N-terminal section of the protein against proteolysis in situ. The four cysteinyl residues of the FAD domain are of special interest. Cys-2 at the tip of the N-terminal extension is likely to be involved in the aggregation behaviour of glutathione reductase. Cys-58 and Cys-63 (formerly Cys-41 and Cys-46) represent the enzyme's redox-active dithiol. Cys-90 with its location at the twofold axis forms a disulfide bridge with Cys-90 of the other peptide chain of the enzyme. This might be related to the fact that both peptide chains contribute to each of the two active centers. In view of the interchain disulfide bridge glutathione reductase should be regarded as a monomeric protein. The sequence of the FAD-binding domain was compared with the sequence of the NADPH-binding domain of glutathione reductase using a computer program. As discussed, the scarcity of sequence similarities does not argue against the assumption that the two nucleotide-binding domains of glutathione reductase originated by gene duplication. The pyrophosphate moiety of FAD binds to a part of the polypeptide chain which in geometric structure, in topology and in sequence resembles the phosphate loops of other nucleotide-binding proteins and of flavodoxin. Using the phosphate loop as a reference, the N-terminal sequence of five flavoproteins can be aligned. The results of Williams et al. on the sequence of lipoamide dehydrogenase (EC 1.6.4.3) and our data on glutathione reductase (EC 1.6.4.2) show clearly that these two mechanistically similar enzymes possess homologous structures.

Amino Acid Sequence↗
PubMedDate not supplied

Hierarchical construct validity of the treatment satisfaction questionnaire for medication (TSQM version II) among outpatient pharmacy consumers.

OBJECTIVES: The objectives of this study were twofold: 1) to evaluate the construct validity of the Treatment Satisfaction Questionnaire for Medication (TSQM v. II) using structural equation modeling (SEM); and 2) to assess its concurrent validity using medication adherence criteria. METHODS: Pharmacy patients filling a new medication prescription (n = 342) were recruited from 14 Michigan pharmacies to participate in a 4-week treatment satisfaction study. The TSQM v. II was tested for model fit against an established theoretical model (the Decisional Balance Model of Treatment Satisfaction) using hierarchical confirmatory factor analysis (HCFA). Regression and discriminant analytic models were used to examine the criterion-related validity of the measure. RESULTS: An exploratory factor analysis, used for TSQM v. II item reduction, revealed a strongly dimensional instrument (Effectiveness, Side Effects, and Convenience) and explained 88% of total pooled variance. Results of an HCFA using the final TSQM v. II items suggested a good model fit with the data (P > 0.54). In support of concurrent validity, the TSQM scales explained between 9% and 20% of the variance in dosing adherence and 60% of the variance in the likelihood of future use. Discriminant analysis demonstrated the superior classification power of the hierarchical model of treatment satisfaction over the discrete attribute model when predicting medication discontinuation. CONCLUSIONS: The TSQM v. II has equivalent measurement characteristics as the TSQM v. I, yet uses four fewer items and more consistent wording. The value of the Decisional Balance Model for estimation of dosing adherence and medication persistence over time is discussed.

Aged↗
PubMed2001

Reduction of the platelet review rate using the two-dimensional platelet method.

Accurate platelet enumeration is critical for optimal treatment of patients with platelet and bleeding disorders, leukemias, and other neoplasias. The majority of automated hematology analyzers count platelets by size differentiation alone, which may result in falsely elevated platelet counts for samples containing interfering particles such as RBC fragments, microcytes, and cell debris. Most analyzers flag questionable platelet counts, necessitating review of results with confirmation by an alternative method, thus increasing the cost of performing platelet counts and delaying results. We studied the effect of a new platelet analysis method, based on measurement of size and refractive index, on the laboratory review rate for platelet counting. We demonstrated that this method yields higher accuracy for platelet counts in samples with interferences, especially for platelet counts less than 50 x 10(3)/microL (< 50 x 10(9)/L). As a result of the 2-dimensional analysis, the review rate for platelet counts was reduced by 65% in our institution, resulting in substantial savings.

Blood Platelets↗
PubMed2002

Optical propagation within a three-dimensional shadowed atmosphere-ocean field: application to large deployment structures.

Estimation of optical shadowing effects that occur on in situ submerged radiance and irradiance measurements conducted in the proximity of a large and complex three-dimensional deployment structure is addressed by use of Monte Carlo simulations. We have applied backward Monte Carlo techniques and variance reduction schemes in three-dimensional radiative transfer computations of in-water light field perturbations by taking into account relevant geometric, environmental, and optical parameters that describe a realistic atmosphere-ocean system. Significant parameters, determined by a sensitivity analysis study, have then been systematically varied for the computation of an extensive set of correction factors, included in look-up tables designed for operational removal of tower-shading uncertainties, which typically induce an approximately 1-10% decrease in absolute radiometric data values near a specific oceanographic tower located in the northern Adriatic Sea. In principle, the proposed correction methodology can be transferred to other deployment systems, instrument casings, and measurement sites if a comprehensive description is provided for the system parameters and their variability.

Journal Article↗
PubMed2006

Combination chemotherapy with estramustine phosphate, ifosfamide and cisplatin for hormone-refractory prostate cancer.

We evaluated the efficiency and toxicity of estramustine phosphate (ECT), ifosfamide (IFM) and cisplatin (CDDP) combination chemotherapy in twenty-one patients with hormone-refractory prostate cancer (HRPC), for which there is currently no effective treatment. Patients received a daily dose of 560 mg ECT in combination with 1.2 g/m2 IFM on days 1 to 5 and 70 mg/m2 CDDP on day 1. This combination therapy was given every 3 to 4 weeks. An objective response of more than 50% reduction in prostate-specific antigen was observed in 9 of 18 patients (50%), and a more than 50% reduction in bi-dimensionally measurable soft-tissue lesions was observed in 2 of 7 patients (29%). The median duration of response among the cases showing partial response was 40 weeks, while the median duration of response of overall partial-response plus stable cases was 30 weeks. The median survival duration of all cases was 47 weeks. Toxicity was modest and acceptable. In conclusion, the ECT, IFM and CDDP combination chemotherapy regimen is a viable treatment option for HRPC. However, in comparison with our previous chemotherapy regimen of IFM and CDDP, no additional long-lasting effects resulting from the inclusion of ECT could be affirmed.

Adult↗
PubMed2000

[Supraconservative breast surgery].

Currently, 30% of the breast biopsies are performed for patients with nonpalpable lesions. The surgical management of these lesions had to evolve to a better three-dimensional targeting and a reduction of the tissue traumatism. The ABBI procedure allows the percutaneous one bloc excision of suspicious mammographically detected lesions with a diameter of less than 2cm. We prospectively evaluated this procedure as a therapeutic tool. Of the 10 malignant lesions with a pathologic size <10mm, 9 (90%) were completely resected with the ABBI device (no residual disease at re-excision of the biopsy site). The results of this preliminary study suggest a potential therapeutic role of the ABBI procedure in the therapeutic arsenal against mammary lesions.

Biopsy↗
PubMed1985

Two-dimensional echocardiographic evaluation of right ventricular size and contractility in acute respiratory failure.

Right ventricular size and contractility were evaluated using two-dimensional echocardiography during the first days of respiratory support in 23 patients requiring mechanical ventilation for acute respiratory failure. Nine patients had normal echocardiographic right ventricular function, and nine other patients had a slightly enlarged right ventricle with normal systolic function. The remaining five patients had a severely enlarged right ventricle with abnormal contractile pattern. In these five patients, two-dimensional echocardiography also showed a reduction in left ventricular size suggesting detrimental ventricular interdependence. All 23 patients had normal left ventricular systolic function by two-dimensional echocardiography.

Acute Disease↗
PubMed1986

Two-dimensional analysis of metabolically and cell surface radiolabeled proteins of some human lymphoid and myeloid leukemia cell lines. I. 35S-methionine labeled, lactoperoxidase radioiodinated and 3H-reductively methylated proteins.

Cell surface and cytoplasmic polypeptides of some human hemopoietic cell lines were radiolabeled by three different techniques: 35S-methionine metabolic radiolabeling, lactoperoxidase catalyzed radioiodination and reductive methylation with formaldehyde and tritiated sodium borohydride. Two-dimensional patterns of 35S-methionine labeled proteins revealed more than 500 separated protein spots with essentially similar general aspects of all examined cell lines, sharing major polypeptides such as those with electrophoretic mobilities of major cytoskeletal proteins. 125I-lactoperoxidase radio-iodinated cell surface protein patterns contained about 30 separated protein macromolecules with some marked differences between lymphoid versus myeloid lines and also between individual cell lines. Two-dimensional patterns of tritiated membrane polypeptides consisted of approximately 200 separated protein spots, some prominent of them appeared with electrophoretic mobilities of major cytoskeletal proteins being common to both 35S-methionine and reductive methylation patterns. Two-dimensional patterns of 35S-methionine labeled and cell surface radioiodinated proteins immunoprecipitated by monoclonal antibodies Bra30 and HL39, recognizing MHC class II antigens, appeared as bimolecular complex of larger acidic and smaller basic chains structurally corresponding to the expected two-dimensional patterns of MHC class II antigens.

Autoradiography↗
PubMed2006

Three-dimensional facial morphometry in skeletal Class III patients. A non-invasive study of soft-tissue changes before and after orthognathic surgery.

Nine patients aged between 18 and 35 years who had severe skeletal Class III malocclusion and moderate-to-severe mandibular asymmetry, were assessed by a non-invasive, landmark-based, three-dimensional system before and after mandibular reduction by sagittal split osteotomy and LeFort I maxillary advancement. The three-dimensional coordinates of 50 facial soft tissue landmarks were collected, and a series of anthropometric measurements was calculated and compared with reference values from 240 healthy subjects of similar sex, age, and ethnic group. Patients were more asymmetrical than normal subjects before the operations, particularly in the gonion. Postoperatively, total and lateral asymmetry was considerably reduced. The three-dimensional approach was a valuable complementary diagnostic aid that enabled quantitative evaluation of the final soft-tissue results without invasive procedures.

Adolescent↗
PubMed2006

Efficient automatic noise reduction of electron tomographic reconstructions based on iterative median filtering.

A simple, fast and efficient noise-reduction protocol for three-dimensional electron tomographic reconstructions of biological material is presented. The approach is based on iterative application of median filtering and shows promise for automatic noise reduction as a pre-processor for automated data analysis tools which aim at segmentation, feature extraction and pattern recognition. The application of this algorithm produces encouraging results for a wide variety of experimental and synthetic electron tomographic reconstructions.

Algorithms↗
PubMed2005

Reducing whole body physiologically based pharmacokinetic models using global sensitivity analysis: diazepam case study.

There are situations in drug development where one may wish to reduce the dimensionality and complexity of whole body physiologically based pharmacokinetic models. A technique for formal reduction of such models, based on global sensitivity analysis, is suggested. Using this approach mean and variance of tissue(s) and/or blood concentrations are preserved in the reduced models. Extended Fourier amplitude sensitivity test (FAST), a global sensitivity technique, takes a sampling approach, acknowledging parameter variability and uncertainty, to calculate the impact of parameters on concentration variance. We used existing literature rules for formal model reduction to identify all possible smaller dimensionally models. To discriminate among those competing mechanistic models extended FAST was used, whereby we treated model structural uncertainty as another factor contributing to the overall uncertainty. A previously developed 14 compartment whole body physiologically based model for diazepam disposition in rat was reduced to three alternative reduced models, with preserved arterial mean and variance concentration profiles.

Animals↗
PubMed2005

Reduction of observer variation using matched CT-PET for lung cancer delineation: a three-dimensional analysis.

PURPOSE: Target delineation using only CT information introduces large geometric uncertainties in radiotherapy for lung cancer. Therefore, a reduction of the delineation variability is needed. The impact of including a matched CT scan with 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) and adaptation of the delineation protocol and software on target delineation in lung cancer was evaluated in an extensive multi-institutional setting and compared with the delineations using CT only. METHODS AND MATERIALS: The study was separated into two phases. For the first phase, 11 radiation oncologists (observers) delineated the gross tumor volume (GTV), including the pathologic lymph nodes of 22 lung cancer patients (Stages I-IIIB) on CT only. For the second phase (1 year later), the same radiation oncologists delineated the GTV of the same 22 patients on a matched CT-FDG-PET scan using an adapted delineation protocol and software (according to the results of the first phase). All delineated volumes were analyzed in detail. The observer variation was computed in three dimensions by measuring the distance between the median GTV surface and each individual GTV. The variation in distance of all radiation oncologists was expressed as a standard deviation. The observer variation was evaluated for anatomic regions (lung, mediastinum, chest wall, atelectasis, and lymph nodes) and interpretation regions (agreement and disagreement; i.e., >80% vs. <80% of the radiation oncologists delineated the same structure, respectively). All radiation oncologist-computer interactions were recorded and analyzed with a tool called "Big Brother." RESULTS: The overall three-dimensional observer variation was reduced from 1.0 cm (SD) for the first phase (CT only) to 0.4 cm (SD) for the second phase (matched CT-FDG-PET). The largest reduction in the observer variation was seen in the atelectasis region (SD 1.9 cm reduced to 0.5 cm). The mean ratio between the common and encompassing volume was 0.17 and 0.29 for the first and second phases, respectively. For the first phase, the common volume was 0 in 4 patients (i.e., no common point for all GTVs). In the second phase, the common volume was always >0. For all anatomic regions, the interpretation differences among the radiation oncologists were reduced. The amount of disagreement was 45% and 18% for the first and second phase, respectively. Furthermore, the mean delineation time (12 vs. 16 min, p<0.001) and mean number of corrections (25 vs. 39, p<0.001) were reduced in the second phase compared with the first phase. CONCLUSION: For high-precision radiotherapy, the delineation of lung target volumes using only CT introduces too great a variability among radiation oncologists. Implementing matched CT-FDG-PET and adapted delineation protocol and software reduced observer variation in lung cancer delineation significantly with respect to CT only. However, the remaining observer variation was still large compared with other geometric uncertainties (setup variation and organ motion).

Aged↗