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At least 1,045 records · Page 58Linked to original sources
PubMed2006

4-chloro-3-hydroxyanthranilate reduces local quinolinic acid synthesis, improves functional recovery, and preserves white matter after spinal cord injury.

Inflammatory processes within the central nervous system (CNS) contribute significantly to the pathogenesis of a broad range of neurologic diseases, including spinal cord injury (SCI). One mechanism by which immune activation causes neurologic symptoms and tissue injury is via the production of neurotoxins by activated macrophages and microglia. In the present study, the role of the endogenous tryptophan metabolite and neurotoxin quinolinic acid (QUIN) in secondary pathology following traumatic SCI was investigated. Adult Hartley guinea pigs were injured by lateral compression of the spinal cord at the 12th thoracic segment (T12). QUIN had accumulated at the site of injury on day 12 post-injury in proportion to the severity of functional neurologic deficits (as assessed by the cutaneus trunci muscle reflex and motor function score at 5 h post-injury). Systemic administration of the 3-hydroxyanthranilate-3,4-dioxygenase (3-HAD) inhibitor, 4-chloro-3-hydroxyanthranilate (4Cl-3HAA; approximately 100 mg/kg every 12 h, beginning 5 h after injury) attenuated local QUIN production and reduced QUIN accumulation at the site of injury by approximately 50% at day 12, without enhanced accumulations of the neuroprotective metabolite kynurenic acid (KYNA). The severity of secondary functional deficits was also reduced by 4Cl-3HAA. In toluidine blue-stained spinal cord sections, the area of surviving intact white matter at the injury site was increased by approximately 100% in the 4Cl-3HAA-treated group. Sparing of both axons and myelin contributed to this increase. These results support the conclusion that QUIN accumulations at the site of injury contribute to secondary functional deficits and tissue damage following SCI.

3-Hydroxyanthranilic Acid↗
PubMed1997

Bone metastases: Part I--Pathophysiology.

Many cancers (especially breast, prostate, and lung cancers) metastasize to the bone. The most frequent site of bone involvement is the axial skeleton (i.e., cranium, ribs, spine, and pelvis). The sequelae of bone metastases include pain, hypercalcemia, pathologic fractures, and spinal cord compression. As patients survive for longer periods, effective management of bone metastases becomes critical to maintaining or improving quality of life. Controlling pain, preventing fractures and oncologic emergencies, and promoting mobility and function are the outcomes of successful management. Use of a clinical algorithm can assist the nurse in identifying bone metastases and managing the clinical sequelae. Knowledge of the pathophysiology and the ability to assess bone metastases will contribute to the nurse's ability to manage the clinical problems and to improve the quality of life of patients with cancer.

Bone Neoplasms↗
PubMed2004

Amplitude spectrum area: measuring the probability of successful defibrillation as applied to human data.

OBJECTIVE: The objective of our study was to examine the effectiveness of an electrocardiographic predictor, amplitude spectral area (AMSA), for the optimal timing of defibrillation shocks in human victims of cardiac arrest. Based on the spectral characteristics of ventricular fibrillation potentials, we examined the probability of successful conversion to an organized viable rhythm, including the return of spontaneous circulation. The incentive was to predict the likelihood of successful defibrillation and thereby improve outcomes by minimizing interruptions in chest compression and minimizing electrically induced myocardial injury due to repetitive high-current shocks. DESIGN: Observational study on human electrocardiographic recordings during cardiopulmonary resuscitation. SETTING: Medical research laboratory of a university-affiliated research and educational institute. PATIENTS: Victims of out-of-hospital cardiac arrest. INTERVENTIONS: Iteration of electrocardiographic records, representing lead 2 equivalent recordings on 108 defibrillation attempts with an automated external defibrillator, of 46 victims of cardiac arrest due to ventricular fibrillation. MEASUREMENTS AND MAIN RESULTS: Three seconds of ventricular fibrillation, recorded immediately preceding delivery of a shock, were analyzed utilizing the AMSA algorithm. AMSA represents a numerical value based on the sum of the magnitude of the weighted frequency spectrum between 3 and 48 Hz. The greater the AMSA value, the greater was the probability of reversal of ventricular fibrillation. At an AMSA value of >13.0 mV-Hz, successful defibrillation yielded a sensitivity of .91 and a specificity of .94. CONCLUSION: AMSA predicts the success of electrical defibrillation with high specificity. AMSA therefore serves to minimize interruptions of precordial compression and the myocardial damage caused by delivery of repetitive and ineffective electrical shocks.

Databases, Factual↗
PubMed1992

System identification for the ECG using CZT.

A new approach for extraction of clinically useful parameters from the ECG signal is presented using the system identification technique of CZT on the DCT-transformed signal. A one to one relationship between the model singularities and the significant points in the time signal is arrived at. The method allows the determination of R-R interval needed in rhythm analysis. The complex cepstrum is used for identifying and removing the effect of zeros outside the unit circle. A significant data compression of 1 in 10 is achieved. A large number of continuous strips of ECG data are analyzed and the results are presented.

Algorithms↗
PubMed1999

Discrete wavelet transform: a tool in smoothing kinematic data.

Motion analysis systems typically introduce noise to the displacement data recorded. Butterworth digital filters have been used to smooth the displacement data in order to obtain smoothed velocities and accelerations. However, this technique does not yield satisfactory results, especially when dealing with complex kinematic motions that occupy the low- and high-frequency bands. The use of the discrete wavelet transform, as an alternative to digital filters, is presented in this paper. The transform passes the original signal through two complementary low- and high-pass FIR filters and decomposes the signal into an approximation function and a detail function. Further decomposition of the signal results in transforming the signal into a hierarchy set of orthogonal approximation and detail functions. A reverse process is employed to perfectly reconstruct the signal (inverse transform) back from its approximation and detail functions. The discrete wavelet transform was applied to the displacement data recorded by Pezzack et al., 1977. The smoothed displacement data were twice differentiated and compared to Pezzack et al.'s acceleration data in order to choose the most appropriate filter coefficients and decomposition level on the basis of maximizing the percentage of retained energy (PRE) and minimizing the root mean square error (RMSE). Daubechies wavelet of the fourth order (Db4) at the second decomposition level showed better results than both the biorthogonal and Coiflet wavelets (PRE = 97.5%, RMSE = 4.7 rad s-2). The Db4 wavelet was then used to compress complex displacement data obtained from a noisy mathematically generated function. Results clearly indicate superiority of this new smoothing approach over traditional filters.

Algorithms↗
PubMed2005

Image analysis for assessing molecular activity changes in time-dependent geometries.

In vivo fluorescence molecular imaging and tomography has facilitated monitoring of genomics and proteomics over time and on the same animal. A highly important issue, however, has been the robust registration of animals imaged at different time points to obtain accurate description of activity and location. This paper presents a method for aligning temporal data of small animals based on surface anatomical features and improving the accuracy of monitoring fluorophore distribution. The method can account for differences in the positioning and compression of small animals and can be extended to three-dimensional as well as to other imaging modalities.

Algorithms↗
PubMedDate not supplied

The consolidation and compressibility properties of some novel directly compressible filler-binders.

The aim of this study was to investigate the consolidation and compressibility properties and also the dilution potentials of some novel directly compressible filler-binders. For this purpose, Ludipress and Cellastose 80 (one-body compounds), Tablettose 70 and Tablettose 80 (alpha-mono agglomerated lactose) were selected. They were diluted at predetermined percentages with Spherolac 100 which is a coarse sieved hydrous crystalline lactose. The consolidation and compressibility properties of the prepared powder mixtures were determined. The experimental data were evaluated by using a computer programme (Basic 80).

Algorithms↗
PubMed2002

[Les démoiselles d'Avignon and "e = m.c2"].

Picasso, mentally travelling around the objects, indicated a process of visual disconnection of their naturals forms which ended in the recovery of the beautiful lines of euclidean geometry. In this paintings and especially in Les Démoiselles d'Avignon, the triangles and circles become plastic materials but they do not form perfect euclidean tridimensional spaces where objects must keep constant sizes and proportions. Thus, Picasso discovered or invented cubism. The characteristic void space of the perspectivistic figurative painting, became substituted by a solid space where vertical, horizontal dimensions and depth were represented in an instant. This "simultaneity" implicitly included the use of time as a fourth dimension in cubist paintings. As in Einstein's relativistic theories, in cubism the volume of the observed objects become compressed and bidimensional, and the notion of absolute space-time is ignored. In a way, cubistic paintings were contemporary illustration of Einstein's relativistic principles.

Algorithms↗
PubMedDate not supplied

Pre-clinical evaluation of a two-channel microwave hyperthermia system with adaptive phase control in a large animal.

A pre-clinical assessment of the heating capabilities of a two-channel 915 MHz Microfocus-1000 hyperthermia system, with adaptive phase control, was carried out in a series of experiments using a large animal model. The results of the experimental measurements of specific absorption rate (SAR) and tissue temperature show that when muscle tissue of the hind legs of pigs was compressed to 6.5-7 cm, then a pair of parallel opposed, coherently driven, transverse electromagnetic wave applicators could elevate the temperature in deep tissue to therapeutic levels without overheating superficial tissues when the phase difference between applicators was determined by the adaptive phase control algorithm.

Animals↗
PubMedDate not supplied

[Anatomo-functional aspects and diagnostic algorithm (of the upper limb pathologies secondary to repeated trauma)].

The epidemiology of work-related musculo-skeletal pathologies of the upper limbs has become significantly relevant in the last years, and a sharp increasing trend can be observed. This paper mainly focuses on the chronic inflammatory and degenerative conditions, which are more complex and difficult to accurately diagnose and treat. A synthesis of the diagnostic picture of the different types, involving the joints, muscles and tendons, and peripheral nerves is provided, with mention of the sensitivity and specificity of the main diagnostic tests. The possible entrapments of the radial, median and ulnar nerves are described in detail. Finally, a brief critical review on the principal movements of the upper limbs which are responsible of the onset of such conditions is presented.

Algorithms↗
PubMed1997

Measures of line jaggedness and their use in foods textural evaluation.

The jaggedness of signatures, such as the force-displacement curves of brittle cereal-based foods, can be a manifestation of physical processes. Consequently, it should be regarded as an inherent property of the system rather than noise that should be discarded. Changes in the degree of jaggedness can provide useful information on the system's performance or on how it is affected by external conditions, such as exposure to moisture. Quantitative assessment of the degree of jaggedness can be done by methods that include statistical analysis, conversion of the record into a Fourier power spectrum, and determination of its apparent fractal dimension. Most can be performed with microcomputers and commercially available software. It is recommended that the jaggedness of any experimental curve or signature be determined by at least two methods or algorithms simultaneously for mutual verification. The magnitude of any single measure of jaggedness is determined by the signature's fluctuations amplitude and frequency. While the amplitude effect can be accounted for by normalization, the frequency cannot. Consequently, only curves having about the same number of points at the pertinent interval can be meaningfully compared. There is, however, a mathematical method, at this time still empirical, that allows meaningful comparison of the jaggedness of signatures obtained at different sampling rates. When several or numerous jagged signatures are recorded simultaneously, as in the case of brittle particulates compressed in bulk, the resulting combined signature is considerably smoothed. This is primarily the result of averaging caused by mutual cancellation of peaks in different directions and reducing the relative weight of any large peak. However, there are mathematical methods, some partly empirical, that enable restoration of the jaggedness of the original signatures.

Algorithms↗
PubMed2003

Conformation-dependent evolution of copolymer sequences.

A "toy model" of molecular evolution of sequences in copolymers is proposed and implemented using a molecular-dynamics-based algorithm. The model involves coupling of conformation-dependent and sequence-dependent properties. It is shown that this model allows the realization of two main possibilities: ascending and descending branches of evolution (in terms of information content of a sequence), depending on the interaction parameters shaping the conformation of a polymer globule. The problem of adequate description of information complexity of copolymer sequences is studied. It is shown that Shannon's entropy or compressibility of a sequence gives preference to random sequences and therefore cannot be applied for this purpose. On the other hand, the Jensen-Shannon divergence measure turns out to give the description of information complexity which corresponds to our intuitive expectations. In particular, this characteristic can adequately describe two branches of evolution mentioned above, exhibiting a singularity on the boundary of these regimes.

Algorithms↗
PubMed2006

Outcomes of surgical treatment for chronic postoperative breast and abdominal pain attributed to the intercostal nerve.

BACKGROUND: Postoperative breast and abdominal pain arising from lesion of the intercostal nerves is an often overlooked and misdiagnosed clinical entity. Typically, affected patients experience a high degree of frustration in addition to persistent pain. Surgical options for management of this pain are not widely reported. STUDY DESIGN: Medical records were reviewed of all consecutive patients of the senior author who had undergone surgical treatment for postoperative breast and abdominal pain since May of 2003. All patients underwent surgical excision of the involved nerve or nerves proximal to the likely area of injury with subsequent implantation of the nerve stump into the muscle. The involved intercostal nerve, inciting procedure, percentage decrease in pain, and followup time were recorded. Success was defined as symptom relief of at least 50% as reported by the patient. Mean followup time and success rates were calculated. RESULTS: Five patients with breast pain and seven patients with abdominal pain underwent surgical treatment. Four of five breast patients (80%) and six of seven abdominal-pain patients (87%) experienced considerable pain relief after operation. Combined, the success rate was 84%. Mean followup duration for breast-pain patients was 8.7 months. Mean followup in abdominal-pain patients was 12.5 months. CONCLUSIONS: Operation appears to be a viable alternative for patients experiencing postoperative pain of the breast and abdomen from lesions of the intercostal nerve. Increased awareness of this diagnosis and the options for its management as presented in our algorithm should help to more quickly alleviate the pain of patients suffering from this disorder.

Abdominal Pain↗
PubMed2006

Towards pointwise motion tracking in echocardiographic image sequences--comparing the reliability of different features for speckle tracking.

In this paper, we studied the problem of feature-based motion tracking in echocardiographic image sequences. We described the relation between possible feature variations and different kinds of tissue motion using a linear convolution model. We also showed that motion-feature decorrelation (which means that the motion parameters estimated using feature tracking fail to represent the underlying tissue motion) compensation is an ill-posed inverse problem. Instead of finding a method that may provide better compensation results than previous approaches, we used an quantitative measure to compare the reliability of tracking features. Experiment results showed that the use of the reliability measure improved the robustness of displacement estimation. With the help of the reliability measure, we compared the performance of different features using simulations and phantom examples. While we noticed that the radio frequency (RF) signal outperforms the B-mode (BM) signal in the analysis of small deformation (e.g., less than 0.1% compression), we also found out that the BM signal works better than the RF signal in the analysis of large deformation (e.g., larger than 2% compression). The use of a band-passed filtered feature does not result in significant improvement in tracking.

Algorithms↗
PubMed2004

A novel shape-based coding-decoding technique for an industrial visual inspection system.

This paper describes a unique single camera-based dimension storage method for image-based measurement. The system has been designed and implemented in one of the integrated steel plants of India. The purpose of the system is to encode the frontal cross-sectional area of an ingot. The encoded data will be stored in a database to facilitate the future manufacturing diagnostic process. The compression efficiency and reconstruction error of the lossy encoding technique have been reported and found to be quite encouraging.

Algorithms↗
PubMed1999

Constitutive model of brain tissue suitable for finite element analysis of surgical procedures.

Realistic finite element modelling and simulation of neurosurgical procedures present a formidable challenge. Appropriate, finite deformation, constitutive model of brain tissue is a prerequisite for such development. In this paper, a large deformation, linear, viscoelastic model, suitable for direct use with commercially available finite element software packages such as ABAQUS is constructed. The proposed constitutive equation is of polynomial form with time-dependent coefficients. The model requires four material constants to be identified. The material constants were evaluated based on unconfined compression experiment results. The analytical as well as numerical solutions to the unconfined compression problem are presented. The agreement between the proposed theoretical model and the experiment is good for compression levels reaching 30% and for loading velocities varying over five orders of magnitude. The numerical solution using the finite element method matched the analytical solution very closely.

Algorithms↗
PubMedDate not supplied

State-of-the-art techniques for lossless compression of 3D medical image sets.

This paper explains the basic principles of lossless two-dimensional (2D) and three-dimensional (3D) image coding at a high level of abstraction. It discusses also a new inter-frame technique for lossless video coding based on intra-frame prediction and inter-frame context modelling. The performance of this technique is compared to that of state-of-the-art 2D coders on CT and MRI data sets from the Visual Human Project. The results show that the inter-frame technique outperforms state-of-the-art intra-frame coders, i.e. Calic and JPEG-LS. The improvement in compression ratio is significant in the case of CT data but is rather small in the case of MRI data.

Algorithms↗
PubMed2003

Combined use of clinical assessment and d-dimer to improve the management of patients presenting to the emergency department with suspected deep vein thrombosis (the EDITED Study).

Suspected deep vein thrombosis (DVT) is a common problem facing emergency physicians. Timely diagnostic testing must be performed to accurately identify patients with DVT. The purpose of this study was to evaluate the safety and effectiveness of a management strategy that combined consideration of clinical pretest probability and a d-dimer test to evaluate patients presenting to the emergency department with suspected deep vein thrombosis (DVT). A prospective cohort study was performed in the emergency departments of four tertiary care institutions involving 1075 patients with suspected DVT. An emergency physician determined the pretest probability for DVT to be low, moderate, or high using an explicit clinical model. A blood sample was taken for d-dimer testing. Subsequent investigations (compression ultrasound, venography) were performed based upon the pretest probability and the d-dimer result. Patients considered at low pretest probability with negative d-dimer had no further diagnostic testing performed. All patients in whom the diagnosis of DVT was excluded by the algorithm did not receive anticoagulant therapy and were followed up for 90 days for the development of proximal DVT or pulmonary embolism. Overall, 195 (18.1%; 95% CI 15.9% to 20.6%) of 1075 patients were confirmed to have proximal DVT. Of the 882 patients who had proximal DVT excluded during the initial evaluation period using the algorithms, four (0.5%; 95% CI 0.1% to 1.2%) were subsequently diagnosed with proximal DVT in the follow-up period, including three patients in the low pretest probability group (1.0%; 95% CI 0.2% to 2.1%) who had normal d-dimer and no additional diagnostic testing performed. None of the 882 patients (0%: 95% CI 0% to 0.5%) developed pulmonary embolism in the follow-up period. A diagnostic strategy for the evaluation of patients with suspected DVT based on pretest probability and d-dimer is safe and feasible in the emergency department setting.

Adult↗