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PubMedDate not supplied

Short malunions of the clavicle: an anatomic and functional study.

The anatomic and functional effects of clavicle malunion, defined as 15 mm of shortening, were evaluated in 10 subjects. Bilateral shoulder computed tomography with 3-dimensional reconstructions was performed. A self-administered questionnaire was completed, and biomechanical testing of subjects was undertaken comparing strength and velocity of movement between shoulders. Mean shoulder scores and visual analog global assessments of shoulder function were significantly worse in the injured shoulder. Biomechanical assessment recorded a reduction in muscular strength for adduction, extension, and internal rotation of the humerus as well as a reduced peak abduction velocity in the injured shoulder (P < .05). Computed tomography assessment showed that clavicular shortening produced increased upward angulation of the clavicle at the sternoclavicular joint (P < .005) and increased anterior scapular version (P < .05). These changes in static anatomic relationships are possible mechanisms limiting shoulder function after short clavicle malunions. Consideration should be given to the prevention of shortening by open reduction and internal fixation, especially in the young, active age group.

Adolescent↗
PubMed2003

Enhancing oxidation of TNT and RDX in wastewater: pre-treatment with elemental iron.

Munitions manufacturing wastewater is commonly treated by adsorption to activated carbon. We are proposing a new munitions manufacturing wastewater treatment system consisting of a reductive pre-treatment process and subsequent Fenton's oxidation to mineralize energetic compounds such as TNT and RDX. The pre-treatment involves reduction of electron-withdrawing nitro groups of TNT and RDX with elemental iron. The iron-treated explosives are then oxidized by Fenton's reagent through the addition of H2O2. The objective of this work is to investigate the feasibility of using elemental iron to convert TNT and RDX to reduction products which may be more oxidizable in subsequent Fenton's oxidation. Results of batch reduction experiments with elemental iron showed complete removal of TNT and RDX and formation of the reduction products within 60 minutes. Results of column experiments showed a rapid and complete removal of TNTand RDX within 9.7 minutes retention time. Fitting observed effluent concentrations to a one-dimensional advection-dispersion equation, we were able to predict the concentration profiles of TNT and RDX in the iron column and calculate the iron column length required for the desired removal. The results of Fenton's oxidation experiments showed that iron pre-treatment enhanced both the rate and extent of TNT and RDX mineralization by Fenton's oxidation.

Adsorption↗
PubMed1990

Multivariate data reduction by principal components, with application to neurological scoring instruments.

Principal components analysis is widely used as a practical tool for the analysis of multivariate data. The aim of this analysis is to reduce the dimensionality of a multivariate data set to the smallest number of meaningful and independent dimensions. The analysis can also provide interpretable linear functions of the original measured variables that may serve as valuable indices of variation. A brief introduction to principal components analysis is given herein, followed by an examination of a particular set of multivariate data accruing from a study of acute brain injuries in a pediatric population, in which severity of brain injury had been assessed with the Glasgow Coma Scale (CGS). Principal components analysis reveals that the GCS sum score is a particularly inefficient summarizer of information in this cohort. The determination of an objective weighting of measured variables, as provided through principal components analysis, is essential in the construction of meaningful neurological scoring instruments.

Coma↗
PubMed1995

Three-dimensional analysis of glomerular morphology in patients with subtotal nephrectomy.

Previous studies documented that single section examination of kidney tissue underestimates glomerulosclerosis and that three-dimensional examination of glomerular morphology improves recognition of the incidence and distribution of sclerotic changes within the glomerular capillary tuft. We have adopted this technique to evaluate the true frequency and the spatial extent of glomerulosclerosis in patients who were subjected to extensive renal mass reduction. We re-evaluated four kidney biopsies of patients with a solitary kidney who had undergone partial nephrectomy for renal-cell carcinoma. Histopathological examination aimed at detection of glomerular sclerotic lesions was performed on serial sections (from 75 to 93 serial sections for each biopsy, 3 microns thick) together with three-dimensional morphometric analysis of glomerular tuft and sclerotic areas using a computer-based image processing system. Results were compared with observations based on more conventional single section evaluation of the same biopsies. Among 65 glomeruli examined by three-dimensional morphometric analysis, only 8% were normal, 42% revealed segmental sclerosis and 51% global sclerosis. These results confirmed that single section evaluation grossly overestimates the number of normal glomeruli (37% vs. 8%, respectively), since the majority of glomeruli classified as normal are indeed affected by sclerotic changes in areas typically out of the section plane. The three-dimensional distribution of sclerosis is characterized by the appearance of multi-focal areas affecting a small capillary tuft volume (< 10%) which ultimately propagate to the entire capillary tuft. Despite the maintenance of renal function, at the time of biopsy in patients with extensive ablation of renal mass, the incidence of glomerulosclerosis affects almost the entire glomerular population.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed2000

Contact Transformations and Determinable Parameters in Spectroscopic Fitting Hamiltonians.

In recent least-squares fits of torsion-rotation spectra of acetaldehyde and methanol it was found possible to adjust more fourth-order parameters than would be expected from traditional contact-transformation considerations. To investigate this discrepancy between theory and practice we have carried out numerical fitting experiments on the simpler three-dimensional (three-Eulerian-angle) asymmetric rotor problem, using J </= 20 unitless energy levels generated artificially from a full orthorhombic Hamiltonian with quadratic through octic operators in the angular momentum components. Results are analyzed using the condition number kappa of the least-squares matrix, which is a measure of its invertibility in the presence of round-off and other errors. When kappa is very large, parameters must be removed from the fit until kappa becomes acceptably small, corresponding to procedures which lead to reduced Hamiltonians in molecular spectroscopy. We find that under certain circumstances kappa can be decreased to an acceptable level for Hamiltonians which are only partially reduced when compared to Watson A and S reductions. Some insight into this behavior is obtained from classical mechanics and from the concept of delayed contact transformations. Transferring this numerical and algebraic understanding to the more complicated four-dimensional methyl-top internal rotor problem supports the empirical observation that presently existing data sets for methanol and acetaldehyde are most efficiently fit using partially reduced Hamiltonians and further suggests that expanding the methanol data set to transitions involving levels of higher J, K, and v(t) would favor even more strongly the use of partially reduced fourth-order Hamiltonians.

Journal Article↗
PubMed2006

Development of a cone angle weighted three-dimensional image reconstruction algorithm to reduce cone-beam artefacts.

OBJECTIVES: Image reconstruction from cone-beam projections collected along a single circular source trajectory is commonly done using the Feldkamp algorithm, which performs well only with a small cone angle. In this report, we propose an algorithm to reduce cone-beam artefacts by increasing the cone angle by several fold to achieve satisfactory image quality at the same radiation dose. METHODS: To examine the factors involved in the occurrence of cone-beam artefacts, a microspheres-phantom was arranged longitudinally at different positions and a computer simulation was performed. Due to differences in projection angle, data projected onto the detector surface were projected along trajectories shown as different periodic functions depending on the distance and position from the mid-plane position. Therefore, projection along several detector channels based on different projection data resulting from different periodic functions is considered responsible for the increase in cone-beam artefacts associated with an increase in the distance of reconstruction planes from the mid-plane position. Our recommended algorithm to reduce such artefacts features a change in weighting with respect to projection data obtained at different projection angles, three-dimensional back-projection of corrected projection data. RESULTS: Numerical phantom simulation and real human head origin study (a prototype cone-beam CT) showed that the effect of the reduction in cone-beam artefacts of an object located at the edges was markedly enhanced at reconstruction planes at positions further from the mid-plane position. CONCLUSION: We propose a projection angle weight-based algorithm to increase the cone angle by several fold to achieve satisfactory image quality at the same radiation dose. These findings confirmed that this algorithm reduces cone-beam artefacts and generates high-quality reconstruction images.

Algorithms↗
PubMed2005

Magnetization dynamics in arrays of strongly interacting magnetic nanocrystals.

Arrays of 6.6 nm iron oxide nanocrystals coated with fatty acid molecules were produced using the Langmuir-Blodgett technique. The arrays had a varying number of layers stacked together, going from two dimensional to three dimensional and two different in-plane interparticle separations. While temperature-dependent ac susceptibility measurements of the isolated nanocrystals obeyed the Neel-Brown relaxation law, the array relaxation deviated significantly from this simple law. This deviation together with the observed dc field influence on the susceptibility-temperature curves, the large shifts in blocking temperatures and reduction in susceptibility-temperature curve widths on going from isolated particles to the arrays indicated collective magnetization dynamics during magnetization freezing. A scaling law analysis of this freezing dynamics yielded different powers for the two different interparticle separations with no dependence on dimensionality. In spite of the spin-glass-like behavior, it is possible that small, magnetically ordered domains of nanocrystals form at low temperature.

Journal Article↗
PubMed2004

Exact image reconstruction on PI-lines from minimum data in helical cone-beam CT.

The development of accurate and efficient algorithms for image reconstruction from helical cone-beam projections remains a subject of active research. In the last few years, a number of quasi-exact and exact algorithms have been developed. Among them, the Katsevich algorithms are of filtered backprojection type and thus possess computational advantages over other existing exact algorithms. In this work, we propose an alternative approach to reconstructing exactly an image from helical cone-beam projections. Based on this approach, we develop an algorithm that requires less data than do the existing quasi-exact and exact algorithms, including the Katsevich algorithms. Our proposed algorithm is also of filtered backprojection type with one-dimensional filtering performed along a PI-line in image space. Therefore, it is (at least) computationally as efficient as the Katsevich algorithms. We have performed a preliminary numerical study to demonstrate and validate the proposed algorithm using computer-simulation data. The implication of the proposed approach and algorithm appears to be significant in that they can naturally address the long object problem as well as the super-short scan problem and, most importantly, in that they provide the opportunity to reconstruct images within any selected region of interest from minimum data, allowing the use of detector with a reduced size, the selection of a minimum number of rotation angles and thus the reduction of radiation dose delivered to the imaged subject.

Algorithms↗
PubMed1985

Effects of reduced left ventricular mass on chamber architecture, load, and function: a study of anorexia nervosa.

We investigated the effects of reduction in left ventricular mass on cavity geometry, afterload, pump function, and exercise performance in 17 patients with anorexia nervosa and in 10 age-and sex-matched normal subjects. Left ventricular mass index determined by two-dimensional echo-cardiography was significantly lower than that in normal subjects (53 +/- 15 vs 79 +/- 18 g/m2; p less than .005). Left ventricular end-diastolic and end-systolic volume indexes were also reduced in patients with anorexia nervosa compared with normal subjects (49 +/- 11 vs 65 +/- 17 ml/m2, p less than .005; 14 +/- 5 vs 19 +/- 4 ml/m2, p less than .025). In spite of the reductions in left ventricular mass and volume indexes, left ventricular chamber architecture described as h/R ratio, mass to volume ratio, and short/long left ventricular axis ratio were normal. Left ventricular afterload assessed as end-systolic meridional and circumferential wall stress was normal (59 +/- 18 vs 79 +/- 19 dyne/cm2 X 10(3) and 170 +/- 26 vs 167 +/- 23 dyne/cm2 X 10(3)). Ejection fraction, percent fractional shortening, and the relationship between end-systolic wall stress and ejection fraction were all within normal limits. In seven patients restudied after a 15% to 20% weight gain, left ventricular mass and volume indexes increased significantly but end-systolic wall stress and ejection fraction did not change. Ten patients with anorexia nervosa and resting heart rates and systolic blood pressures significantly lower than control values underwent treadmill testing. Exercise duration, peak heart rate, peak systolic blood pressure, and peak oxygen consumption in these patients were all significantly lower than normal. The hypotensive effect of fasting resulted in an initial decrease in afterload, which was the stimulus for reduction in left ventricular mass. The left ventricular remodeling associated with the mass reduction occurred in such a way that (1) orthogonal, meridional, and circumferential wall stresses were normalized, (2) normal chamber shape and architecture were maintained, and (3) chamber function and stress-shortening relationships were preserved. Thus down-regulation of left ventricular mass per se, like up-regulation of left ventricular mass, is not associated with abnormal left ventricular function.

Adolescent↗
PubMed2001

Reduction in matrix metalloproteinase production by tendon and synovial fibroblasts after a single exposure to 5-fluorouracil.

This study investigated the effect of treatment with 5min exposures to 5-fluorouracil (5-FU) on the production of matrix metalloproteinases (MMPs) by endotenon and synovial fibroblasts. Fibroblasts were grown from the flexor tendons of New Zealand White rabbits and were then exposed to varying concentrations (ranging from 0.25 mg x ml(-1)to 25 mg x ml(-1)of 5-FU for 5 min. The treated fibroblasts were suspended in a three-dimensional collagen lattice. The conditioned media from these collagen lattices were then analysed for MMP production using gelatin zymography on days 1, 3 and 7 after treatment. In the majority of cases this treatment produced a dose- and time-dependent reduction in total MMP production by both cell lines, specifically in the production of MMPs 2 and 9. This reduction was significant for most concentrations (P< or =0.01-P< or =0.05) when compared to phosphate-buffered-saline-treated controls. We conclude that 5-FU may reduce adhesions by limiting the migratory capacity of synovial fibroblasts (extrinsic healing).

Animals↗
PubMed1998

Alteration of nuclear matrix protein composition during apoptosis in rat embryo cells.

Alteration of the nuclear matrix protein composition during active cell death was investigated by high resolution 2-dimensional gel electrophoresis and computer-assisted image analysis. Nuclear matrices were isolated from purified nuclei of a rat embryo cell line showing an immediate apoptotic response to serum reduction. While cell shrinkage and cytoplasmic compaction, characteristic features of apoptosis, were induced, the nuclear matrix protein pattern was not altered 1 h after induction of apoptosis. However, two sets of novel nuclear matrix protein spots appeared with differing kinetics within the following 5 h of apoptosis. They consisted of five and six protein spots, respectively. In addition, the intensity of five nuclear matrix protein spots that had already been present in the uninduced cells increased continuously within an observation period of 12 h. These coincidences point to a potential involvement of the described nuclear matrix proteins in the apoptotic process.

Animals↗
PubMed1999

Ultra-short echo-time 2D time-of-flight MR angiography using a half-pulse excitation.

Flow-related artifacts remain a significant concern for magnetic resonance (MR) angiography because their appearance in angiograms adversely impacts accuracy in evaluation of arterial stenoses. In this paper, a half-pulse excitation scheme for improved two-dimensional time-of-flight (2D TOF) angiography is described. The proposed method eliminates the need for gradient moment nulling (of all orders), providing significant reductions in spin dephasing and consequent artifactual signal loss. Furthermore, because the post-excitation refocusing and flow compensation gradients are obviated, the achievable echo time is dramatically shortened. The half-pulse excitation is employed in conjunction with a fast radial-line acquisition, allowing ultra-short echo times on the order of 250-300 microsec. Radial-line acquisition methods also provide additional benefits for flow imaging: effective mitigation of pulsatile flow artifacts, full k-space coverage, and decreased scan times. The half-pulse excitation/radial-line sequence demonstrated improved performance in initial clinical evaluations of the carotid bifurcation when compared with a conventional 2D TOF sequence.

Action Potentials↗
PubMed1995

Analysis of the cbbF genes from Alcaligenes eutrophus that encode fructose-1,6-/sedoheptulose-1,7-bisphosphatase.

The cbbF genes of the facultative chemoautotroph Alcaligenes eutrophus H16 are part of two highly homologous cbb operons. Both the chromosomal and the megaplasmid pHG1-borne copy of cbbF were cloned and sequenced. Subsequent analyses including comparison with known sequences from other organisms and heterologous expression in Escherichia coli revealed that each of the genes encodes fructose-1,6-bisphosphatase (FBPase). A closely related activity likewise operating in the Calvin carbon reduction cycle, sedoheptulose-1,7-bisphosphatase, was also catalyzed by the two isoenzymes which were purified from autotrophically grown cells of A. eutrophus. Two-dimensional gel electrophoresis allowed the separation of the cbbF gene products. Preliminary physical evidence by Southern hybridization with a heterologous gene probe was obtained for the existence of a third FBPase gene, fbp, on the chromosome of the organism. Its product is probably involved in the heterotrophic carbon metabolism.

Alcaligenes↗
PubMedDate not supplied

Changes in protein expression during melanoma differentiation determined by computer analysis of 2-D gels.

Cytodifferentiation in many melanocytic cells is regulated through the adenylate cyclase-cAMP pathway. To analyse the molecular changes associated with this process we have compared the proteins produced by two closely related cell lines which, though derived from a single cell line, respond very differently to modulation of this signalling pathway. The human melanoma cell line DX3 shows little change in in vitro characteristics following treatment with cAMP elevating agents; in contrast the more malignant DX3 LT5.1 variant, derived from the DX3 parental line, shows pronounced dendrification, decreased proliferation and a reduction in metastatic capacity after similar treatment. The two cell lines were treated with phosphodiesterase inhibitors for 5 days and then processed for two-dimensional gel characterization using an immobilized pH gradient for the IEF dimension. Proteins were detected by silver staining the gels and protein intensities were digitized using a laser densitometer. Two-dimensional gel patterns were edited, matched and a melanoma protein database of 637 spots constructed using PDQUEST software on an Orion 1/05 computer. Eleven proteins were lost and four new proteins were detected in both cell lines following treatment. Twenty-two proteins were present in DX3 LT5.1 after treatment but not in untreated lines or treated DX3. These differentially expressed proteins may be associated with the observed changes in differentiation patterns and metastasis. Our results illustrate the resolving power of this technique and suggest potential applications to the study of cellular differentiation.

Animals↗
PubMed1995

Does hypotension during dobutamine stress echocardiography correlate with anatomic or functional cardiac impairment?

The development of hypotension during various exercise stress tests has been correlated with the presence of multivessel coronary artery disease and impaired left ventricular contractility. Hypotension may also occur during dobutamine stress echocardiography; however, its anatomic and functional significance remains unknown. As part of an ongoing study of restenosis, dobutamine stress echocardiography and diagnostic cardiac catheterization were performed on the same day in 105 outpatients approximately 6 months after percutaneous coronary revascularization (balloon angioplasty or directional coronary atherectomy) to determine the anatomic and functional significance of dobutamine-induced hypotension. Dobutamine was infused in stepwise increments to a maximum rate of 30 micrograms/kg/min. Hypotension was defined as a reduction in systolic blood pressure of > or = 15 mm Hg. Anatomic abnormalities were defined by quantitative coronary angiography and functional abnormalities by digitized two-dimensional stress echocardiography. Clinical, angiographic, hemodynamic, and electrocardiographic data underwent multivariable regression analysis to determine their ability to predict independently the development of dobutamine-induced hypotension. Dobutamine-induced hypotension was not associated with the presence of severity of coronary artery disease or with echocardiographic wall motion abnormalities. Univariable predictors of stress-induced hypotension included high baseline systolic blood pressure, advanced age, and high left ventricular ejection fraction. Only a high baseline systolic blood pressure contributed independent predictive information in multivariable stepwise logistic regression analysis. Therefore, the development of hypotension during dobutamine stress echocardiography, unlike that during traditional exercise stress tests, is not associated with the presence of significant coronary artery disease or left ventricular dysfunction.

Age Factors↗
PubMed1991

Modulation of cytosine arabinoside toxicity by 3-deazauridine in a murine leukemia model.

3-Deazauridine (DAUrd), a competitive inhibitor of CTP synthetase, inhibits both RNA and DNA synthesis. Murine leukemia cells resistant to cytosine arabinoside (ara-C) due to a deletion of deoxycytidine kinase are collaterally sensitive to DAUrd, which inhibits the de novo production of CTP and hence results in dCTP depletion. We evaluated DAUrd in combination with the palmitate derivative of ara-C (palmO-ara-C) in mice bearing L1210 leukemia cells with a subpopulation resistant to ara-C. Both simultaneous administration and a sequential schedule of palmO-ara-C at its maximally tolerated dose (MTD), followed by DAUrd treatment, failed to produce a therapeutic gain. We also studied whether non-toxic doses of DAUrd (15-250 mg/kg i.p. at h 0 and 6 on days 4 and 8) could modulate the antileukemic activity of palmO-ara-C (7.5-120 mg/kg i.p. at h 3 on days 4 and 8). The addition of DAUrd produced a modest (but statistically significant) prolongation of life span and a further 2-log10 reduction in tumor burden compared to the same dose of palmO-ara-C alone, and resulted in long-term survivors in five of 30 treated animals. Two-dimensional dose-response analysis of the survival data indicated a positive drug interaction (p less than or equal to 0.01) when the dosage of DAUrd was modeled to reflect an apparent threshold effect. Cyclopentenyl cytosine (CPE-C; 0.625-2.5 mg/kg i.p. at h 0 and 6 on days 4 and 8), a more potent inhibitor of CTP synthetase, was also given with palmO-ara-C. This combination resulted in an additional 2-6 log10 units of cell kill and occasional long-term survivors at palmO-ara-C dosages that alone resulted in no more than 2 log10 units of cell kill and no long-term survivors. However, DAUrd and CPE-C given with palmO-ara-C increased host toxicity, compromising the tolerable dose of palmO-ara-C. Single-agent palmO-ara-C given at its MTD produced a similar reduction in tumor burden and increase in life span compared to the highest palmO-ara-C dose that could be given in combination with either modulator.

3-Deazauridine↗
PubMed1987

Crossed cerebello-cerebral diaschisis in a patient with cerebellar infarction.

After supratentorial infarction crossed cerebellar diaschisis has been described. This report concerns the rare phenomenon of crossed cerebral diaschisis in cerebellar infarction. Relative distribution of cerebral and cerebellar blood flow was measured using three-dimensional, qualitative single-photon-emission-computed-tomography (SPECT) with a rotating gamma camera and 123I-IMP. Regional cerebral blood flow was calculated with the two-dimensional, quantitative 133Xe-inhalation-technique. Reduced uptake was observed in the left cerebral hemisphere (-13.9%) contralateral to the cerebellar infarction with the most marked reduction in the left premotor region (-21%). This might be explained by the functional depression of cerebello-ponto-thalamo-cerebral pathways.

Adult↗
PubMed2004

Methodology for improved detection of coronary stenoses with computed tomographic angiography.

BACKGROUND: Noninvasive angiography is a promising technique for visualization of the coronary lumen; however, current methodologies lead to limited accuracy. We assessed the accuracy of electron beam computed tomographic angiography (EBA) for detection of coronary stenoses, using improved triggering techniques and thinner slice collimation. METHODS: Eighty-six patients with suspected coronary disease were studied with EBA and conventional invasive coronary angiography. Electrocardiographic triggering was performed at a fixed time in end systole to reduce cardiac motion. Thin (1.5 mm) slices were obtained with 1.5 mm table incrementation. In axial (2-dimensional) EBA images and 3-dimensional reconstructions, all coronary arteries and side branches with a diameter of >or=1.5 mm were assessed for the presence of stenoses with >50% diameter reduction. Both EBA and invasive angiographic images were assessed in a blinded manner. RESULTS: In comparison to invasive coronary angiography, EBA correctly classified 49 of 53 patients (92%) as having at least 1 coronary stenosis. Overall, 103 stenoses with >50% diameter reduction were present, and 93 of these lesions were correctly detected by EBA (sensitivity 90%, specificity 93%, positive predictive value 84%, and negative predictive value 96%). Only 5% of vessels could not be assessed, predominantly due to significant calcification. CONCLUSIONS: Thinner slice collimation and end-systolic electrocardiographic triggering improves accuracy and assessment of coronary EBA for the detection of obstructive coronary artery disease, making this study clinically useful in the evaluation of obstructive coronary artery disease.

Coronary Angiography↗