848 resultados para Carbotermal reduction


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Postmortem investigation is increasingly supported by computed tomography (CT) and magnetic resonance imaging, in which postmortem minimal invasive angiography has become important. The newly introduced approach using an aqueous contrast agent solution provided excellent vessel visualization but was suspected to possibly cause tissue edema artifacts in histological investigations. The aim of this study was to investigate on a porcine heart model whether it is possible to influence the contrast agent distribution within the soft tissue by changing its viscosity by dissolving the contrast agent in polyethylene glycol (PEG) as a matrix medium. High-resolution CT scans after injection showed that viscosities above c. 15 mPa s (65% PEG) prevented a contrast agent distribution within the capillary bed of the left ventricular myocardium. Thereby, the precondition of edema artifacts could be reduced. Its minimal invasive application on human corpses needs to be further adapted as the flow resistance is expected to differ between different tissues.

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Myocardial depression after cardiac surgery is modulated by cardiopulmonary bypass (CPB) and the underlying heart disease. The sodium pump is a key component for myocardial function. We hypothesized that the change in sodium pump expression during CPB correlates with intraoperative and postoperative laboratory and clinical parameters in neonates and children with various congenital heart defects. Sodium pump isoforms alpha1 (ATP1A1) and alpha3 (ATP1A3) mRNA expression in right atrial myocardium, excised before and after CPB, was quantified. Groups were assigned according to presence (VO group, n = 8) or absence (NO group, n = 8) of right atrial volume overload. CPB and aortic clamp time correlated with postoperative troponin-I values and ICU stay. ATP1A1 (P = 0.008) and ATP1A3 (P = 0.038) mRNA expression were significantly reduced during CPB. Longer aortic clamp times were associated with lower postoperative ATP1A1 (P = 0.045) and ATP1A3 (P = 0.002) mRNA expression. Low postoperative ATP1A1 (P = 0.043) and ATP1A3 (P = 0.002) expressions were associated with high troponin-I values. These results were restricted to the VO group. No correlation of sodium pump mRNA expression was found with the duration of ICU stay or ventilation. The postoperative troponin-I and clinical parameters correlated with the length of CPB, regardless of volume overload. In contrast, only dilated right atrium seemed to be susceptible to CPB in terms of sodium pump expression, showing a reduction during the operation and a correlation of sodium pump with postoperative troponin-I values.

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This paper presents a novel technique to create a computerized fluoroscopy with zero-dose image updates for computer-assisted fluoroscopy-based close reduction and osteosynthesis of diaphyseal fracture of femurs. With the novel technique, repositioning of bone fragments during close fracture reduction will lead to image updates in each acquired imaging plane, which is equivalent to using several fluoroscopes simultaneously from different directions but without any X-ray radiation. Its application facilitates the whole fracture reduction and osteosynthesis procedure when combining with the existing leg length and antetorsion restoration methods and may result in great reduction of the X-ray radiation to the patient and to the surgical team. In this paper, we present the approach for achieving such a technique and the experimental results with plastic bones.

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Background: A growing body of literature suggests that caregiving burden is associated with impaired immune system functioning, which may contribute to elevated morbidity and mortality risk among dementia caregivers. However, potential mechanisms linking these relationships are not well understood. The purpose of this study was to investigate whether stress-related experience of depressive symptoms and reductions in personal mastery were related to alterations in ss2-adrenergic receptor sensitivity.Methods: Spousal Alzheimer's caregivers (N = 106) completed measures assessing the extent to which they felt overloaded by their caregiving responsibilities, experienced depressive symptoms, and believed their life circumstances were under their control. We hypothesized that caregivers reporting elevated stress would report increased depressive symptoms and reduced mastery, which in turn would be associated with reduced ss2- adrenergic receptor sensitivity on peripheral blood mononuclear cells (PBMC), as assessed by in vitro isoproterenol stimulation.Results: Regression analyses indicated that overload was negatively associated with mastery (beta = -0.36, p = 0.001) and receptor sensitivity (beta = -0.24, p = 0.030), whereas mastery was positively associated with receptor sensitivity (beta = 0.29, p = 0.005). Finally, the relationship between overload and receptor sensitivity diminshed upon simultaneous entry of mastery. Sobel's test confirmed that mastery significantly mediated some of the relationship between overload and receptor sensitivity (z = -2.02, p = 0.044).Conclusions: These results suggest that a reduced sense of mastery may help explain the association between caregiving burden and reduced immune cell ss2-receptor sensitivity.

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In Switzerland, harm-reduction programs have the support of the national government and many localities, in congruence with much of the rest of Europe and in contrast with the United States, and take place in public settings. The threat of AIDS is recognized as the greater harm. This paper describes the overall national program and highlights the experience from one city; the program is noteworthy because it is aimed at gathering comparative data from controlled trials.

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The purpose of this study was to evaluate the neuroimaging quality and accuracy of prospective real-time navigator-echo acquisition correction versus untriggered intrauterine magnetic resonance imaging (MRI) techniques. Twenty women in whom fetal motion artifacts compromised the neuroimaging quality of fetal MRI taken during the 28.7 +/- 4 week of pregnancy below diagnostic levels were additionally investigated using a navigator-triggered half-Fourier acquired single-shot turbo-spin echo (HASTE) sequence. Imaging quality was evaluated by two blinded readers applying a rating scale from 1 (not diagnostic) to 5 (excellent). Diagnostic criteria included depiction of the germinal matrix, grey and white matter, CSF, brain stem and cerebellum. Signal-difference-to-noise ratios (SDNRs) in the white matter and germinal zone were quantitatively evaluated. Imaging quality improved in 18/20 patients using the navigator echo technique (2.4 +/- 0.58 vs. 3.65 +/- 0.73 SD, p < 0.01 for all evaluation criteria). In 2/20 patients fetal movement severely impaired image quality in conventional and navigated HASTE. Navigator-echo imaging revealed additional structural brain abnormalities and confirmed diagnosis in 8/20 patients. The accuracy improved from 50% to 90%. Average SDNR increased from 0.7 +/- 7.27 to 19.83 +/- 15.71 (p < 0.01). Navigator-echo-based real-time triggering of fetal head movement is a reliable technique that can deliver diagnostic fetal MR image quality despite vigorous fetal movement.

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Electroencephalograms (EEG) are often contaminated with high amplitude artifacts limiting the usability of data. Methods that reduce these artifacts are often restricted to certain types of artifacts, require manual interaction or large training data sets. Within this paper we introduce a novel method, which is able to eliminate many different types of artifacts without manual intervention. The algorithm first decomposes the signal into different sub-band signals in order to isolate different types of artifacts into specific frequency bands. After signal decomposition with principal component analysis (PCA) an adaptive threshold is applied to eliminate components with high variance corresponding to the dominant artifact activity. Our results show that the algorithm is able to significantly reduce artifacts while preserving the EEG activity. Parameters for the algorithm do not have to be identified for every patient individually making the method a good candidate for preprocessing in automatic seizure detection and prediction algorithms.

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Carotid sinus baroreceptors are involved in controlling blood pressure (BP) by providing input to the cardiovascular regulatory centers of the medulla. The acute effect of temporarily placing an electrode on the carotid sinus wall to electrically activate the baroreflex was investigated. We studied 11 patients undergoing elective carotid surgery. Baseline BP was 146+30/66+/-17 mm Hg and heart rate (HR) 72+/-7 bpm (mean +/- standard deviation). An electrode was placed upon the carotid sinus and after obtaining a steady state baseline of BP and HR, an electric current was applied and increased in 1-volt increments. A voltage dependent and highly significant reduction in BP was observed which averaged 18+/-26* and 8.0+/-12 mm Hg for systolic BP and diastolic BP, respectively. Maximal reductions occurred at 4.4+/-1.2 V: 23+/-24 mm Hg*, 16+/-10 mm Hg* and 7+/-12 bpm* for systolic BP, diastolic BP and HR, respectively ( = p <.05). Thus, electrical stimulation of the carotid sinus activates the carotid baroreflex resulting in a reduction in BP and HR. This presents a proof of concept for device based baroreflex modulation in acute BP regulation and adds to the available data which provide a rationale for evaluating this system in the context of chronic BP reduction in hypertensive patients.

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The aim of this work is to investigate to what extent it is possible to use the secondary collimator jaws to reduce the transmitted radiation through the multileaf collimator (MLC) during an intensity modulated radiation therapy (IMRT). A method is developed and introduced where the jaws follow the open window of the MLC dynamically (dJAW method). With the aid of three academic cases (Closed MLC, Sliding-gap, and Chair) and two clinical cases (prostate and head and neck) the feasibility of the dJAW method and the influence of this method on the applied dose distributions are investigated. For this purpose the treatment planning system Eclipse and the Research-Toolbox were used as well as measurements within a solid water phantom were performed. The transmitted radiation through the closed MLC leads to an inhomogeneous dose distribution. In this case, the measured dose within a plane perpendicular to the central axis differs up to 40% (referring to the maximum dose within this plane) for 6 and 15 MV. The calculated dose with Eclipse is clearly more homogeneous. For the Sliding-gap case this difference is still up to 9%. Among other things, these differences depend on the depth of the measurement within the solid water phantom and on the application method. In the Chair case, the dose in regions where no dose is desired is locally reduced by up to 50% using the dJAW method instead of the conventional method. The dose inside the chair-shaped region decreased up to 4% if the same number of monitor units (MU) as for the conventional method was applied. The undesired dose in the volume body minus the planning target volume in the clinical cases prostate and head and neck decreased up to 1.8% and 1.5%, while the number of the applied MU increased up to 3.1% and 2.8%, respectively. The new dJAW method has the potential to enhance the optimization of the conventional IMRT to a further step.

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Dose reduction in digital panoramic radiography was studied. Intentional underexposure was performed with the Orthophos DS while six different human mandibles were radiographed. Exposure settings were 69 kV/15 mA (standard), 64 kV/16 mA, and 60 kV/16 mA. Standardized spherical defects, each either 1 or 1.25 mm in diameter, were simulated in 288 of 432 images, and seven observers decided whether defects were present or not. Areas under the receiver operating characteristics curves were calculated. They showed no significant differences in the detectability of the 1-mm defect at 69, 64, or 60 kV. For the 1.25-mm defect, no difference was found between the 69 and 60 kV images, but a statistically significant different detectability was found for 64 kV images in comparison with both 69 and 60 kV images. A dose reduction of up to 43% was ascertained with a Pedo-RT-Humanoid phantom when panoramic radiography was performed at 60 kV/16 mA. The conclusion is that with the Orthophos DS, it seems possible to reduce the dose rate of x-rays without loss of diagnostic quality in the case of radiolucent changes.

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OBJECTIVES: Residual airspace following thoracic resections is a common clinical problem. Persistent air leak, prolonged drainage time, and reduced hemostasis extend hospital stay and morbidity. We report a trial of pharmacologic-induced diaphragmatic paralysis through continuous paraphrenic injection of lidocaine to reduced residual airspace. The objectives were confirmation of diaphragmatic paralysis and possible procedure related complications. METHODS: Six eligible patients undergoing resectional surgery (lobectomy or bilobectomy) were included. Inclusion criteria consisted of: postoperative predicted FEV1 greater than 1300 ml, right-sided resection, absence of parenchymal lung disease, no class III antiarrhythmic therapy, absence of hypersensitivity reactions to lidocaine, no signs of infection, and informed consent. Upon completion of resection an epidural catheter was attached in the periphrenic tissue on the proximal pericardial surface, externalized through a separate parasternal incision, and connected to a perfusing system injecting lidocaine 1% at a rate of 3 ml/h (30 mg/h). Postoperative ICU surveillance for 24h and daily measurement of vital signs, drainage output, and bedside spirometry were performed. Within 48 h fluoroscopic confirmation of diaphragmatic paralysis was obtained. The catheter removal coincided with the chest tube removal when no procedural related complications occurred. RESULTS: None of the patients reported respiratory impairment. Diaphragmatic paralysis was documented in all patients. Upon removal of catheter or discontinuation of lidocaine prompt return of diaphragmatic motility was noticed. Two patients showed postoperative hemodynamic irrelevant atrial fibrillation. CONCLUSION: Postoperative paraphrenic catheter administration of lidocaine to ensure reversible diaphragmatic paralysis is safe and reproducible. Further studies have to assess a benefit in terms of reduction in morbidity, drainage time, and hospital stay, and determine the patients who will profit.