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PubMedDate not supplied

Expression of transforming growth factor beta(1), beta(3), and basic fibroblast growth factor in full-thickness skin wounds of equine limbs and thorax.

OBJECTIVE: To map the expression of transforming growth factor (TGF)-beta(1), TGF-beta(3), and basic fibroblast growth factor (bFGF) in full-thickness skin wounds of the horse. To determine whether their expression differs between limbs and thorax, to understand the pathogenesis of exuberant granulation tissue. STUDY DESIGN: Six wounds were created on one lateral metacarpal area and one midthoracic area of each horse. Sequential wound biopsies allowed comparison of the temporal expression of growth factors between limb and thoracic wounds. ANIMALS: Four 2- to 4-year-old horses. METHODS: Wounds were assessed grossly and histologically at 12 and 24 hours, and 2, 5, 10, and 14 days postoperatively. ELISAs were used to measure the growth factor concentrations of homogenates of wound biopsies taken at the same timepoints. RESULTS: TGF-beta(1) peaked at 24 hours in both locations and returned to baseline in thoracic wounds by 14 days but remained elevated in limb wounds for the duration of the study. Expression kinetics of TGF-beta(3) differed from those of TGF-beta(1). TGF-beta(3) concentrations gradually increased over time, showing a trend toward an earlier and higher peak in thoracic compared with limb wounds. bFGF expression kinetics resembled those of TGF-beta(1), but no statistically significant differences existed between limb and thoracic wounds. CONCLUSIONS: Growth factor expression is up-regulated during normal equine wound repair. TGF-beta(1) and TGF-beta(3) show a reciprocal temporal regulation. Statistically significant differences exist between limb and thoracic wounds with respect to TGF-beta(1) expression. CLINICAL RELEVANCE: The persistence of TGF-beta(1) expression in leg wounds may be related to the development of exuberant granulation tissue in this location, because TGF-beta(1) is profibrotic.

Animals↗
PubMed1980

[Longitudinal data of physical growth of healthy children. III. Circumferences of thorax, upper arm, thigh and calf of children aged 2 to 15 years (author's transl)].

From 1968--1978 a longitudinal study was performed concerning development of thorax, upper arm, thigh and calf circumferences in 709 boys and 711 girls 2--15 years old. In boys the mean increase in thoracic circumference amounted to 32.9 cm, in upper are circumference to 8.3 cm, in thigh circumference to 20.6 cm and in calf circumference to 13.0 cm. The corresponding circumferences in girls amounted to 30 cm, 7.9 cm, 22.4 cm and 12.7 cm. In boys the circumferences developed almost linearly until year 15. Girls had the same linear development until year 13. Between years 14 and 15 girls had in increased development of all circumferences studied.

Adolescent↗
PubMed2002

A mathematical model of the stability control of human thorax and pelvis movements during walking.

A mathematical model is developed to study the human thorax and pelvis movements in the frontal plane during normal walking. The model comprises of two-link base-excited inverted pendulums with one-degree of rotational freedom for each link. Since the linear motion of the pelvis has a significant effect on the upper body stability, this effect is included in the model by having a base point moving in the frontal plane in a general way. Furthermore, because the postural stability is the primary requirement of normal human walking, the control law is developed based on Lyapunov's stability theory, which guarantees the stability of the pendulum system around the up-right position. To evaluate the model, the simulation results, including the angular displacement of each link and the torque applied on each link, are compared with those from gait measurements. It is shown that the simulation results match those from gait measurements closely. These results suggest that the proposed model can provide a useful framework for analysis of postural control mechanisms.

Algorithms↗
PubMed1983

Electrical impedance imaging of the thorax.

In this paper, we propose to develop a new imaging technology, computerized impedance tomography (CIT) for imaging the thorax. Our study involves reconstructing images of thoracic transverse plane impedance distributions noninvasively and nondestructively and exploring the potential of CIT. We overcome the reconstruction problem due to nonlinear and nonplanar current paths in impedance imaging by solving Laplace's equation numerically for every iteration and by using a new back-projection algorithm to modify the impedance profile. We discuss advantages and disadvantages associated with impedance imaging, the computer model, and back-projection algorithms used in reconstructing impedance images. We present reconstructed impedance images with 8 projection angles and different projection methods. We identify important variables affecting the quality of reconstructed images, and discuss the resolution and accuracy of this imaging technique. We summarize numerical aspects, computer requirement, and limitations of impedance imaging. We also discuss the future of impedance imaging.

Computers↗
PubMed1999

Source localization in an inhomogeneous physical thorax phantom.

The influence of lung inhomogeneities on focal source localizations in electrocardiography (ECG) and magnetocardiography (MCG) is investigated. A realistically shaped physical thorax phantom with cylindrical lung inhomogeneities is used for electric and magnetic measurements. The lungs are modelled with a special ionic exchange membrane which allows different conductivity compartments without influencing the free ionic current flow. The dipolar current sources are composed of platinum wire and located at different depths and directions between the lung inhomogeneities. We localized the current dipoles with different boundary element method (BEM) models, based on electrical data and simultaneous electrical and magnetic data. Our results indicate the possibility of superadditive information gain by combining electrical and magnetic data for source reconstructions. We found a significant influence of the inhomogeneities on both the calculated source location and the calculated source strength. Mislocalizations of up to 16 mm and wrong dipole strengths of up to 52% were obtained when the lung inhomogeneities were not taken into account for source localization. Dipoles parallel to the lungs showed a larger localization error in depth than dipoles perpendicular to the lungs. We conclude that the incorporation of lung inhomogeneities will improve source localization accuracy in ECG and MCG.

Body Surface Potential Mapping↗
PubMed1992

Imaging the complex impedance of the thorax.

Respiration-related changes in the complex impedance were obtained on the thorax in three volunteers. The real part of the image clearly showed the lungs as regions of increased conductivity on expiration. The imaginary part of the image, reflecting changes in the ratio of permittivity to conductivity, showed a central negative region surrounded by a positive region extending to the periphery of the lungs. These features may be due to movement of the diaphragm and liver within the sensitive volume during respiration.

Adult↗
PubMed1985

Heart sound propagation in the human thorax.

Simultaneous quantitative recordings of pressure in the aorta near a prosthetic valve and at two locations externally on the chest provide data on certain aspects of sound propagation in the human thorax. On the basis of the different speeds of propagation, it is possible to distinguish between the longitudinal and transverse vibrations contributing to the external phonocardiographic signal. Digital signal processing was employed to derive transfer functions, correlations and power spectra.

Acoustics↗
PubMed2002

Preliminary static EIT images of the thorax in health and disease.

The results of a preliminary clinical evaluation of a one-frequency electrical impedance tomography (EIT) system enabling static in vivo imaging are presented. The design of the measuring system and image reconstruction software are described. Thirty-one subjects were examined and divided into four clinical groups. The first group consisted of 22 patients with clinical diagnosis of lung cancer with tumour localization in one lung. The second group consisted of seven healthy subjects. A patient after a one-sided pneumectomy and another with one-sided emphysema diagnosis were also examined. Static EIT images of a healthy human chest and a chest with various abnormalities are given and discussed. The evaluated system distinguishably visualizes various states of lungs and thorax including lung cancer. The average static conductivity of an affected lung in the first clinical group statistically differs from the average conductivity of a healthy lung. In spite of low spatial resolution, according to preliminary results, the method can be sensitive to cancer and other lung diseases in screening investigations.

Algorithms↗
PubMed1990

High thoracic segmental epidural anesthesia diminishes sympathetic outflow to the legs, despite restriction of sensory blockade to the upper thorax.

To evaluate whether, after high thoracic segmental epidural anesthesia, sympathetic blockade spreads caudally beyond sensory blockade, we assessed regional skin temperatures by infrared telethermometry in 53 nonpremedicated patients at constant ambient temperature. Either bupivacaine (4.2 ml, 0.75%, n = 10) or an equal volume of saline (placebo, n = 10) was injected at the C7-T2 epidural space in a randomized double-blinded fashion. Results were contrasted to those observed after midthoracic (T6-T9, n = 13) and lumbar (L2-T12, n = 10) epidural injection of an identical dose of bupivacaine or saline (n = 10). Despite restriction of sensory block to the upper thorax with high thoracic epidural anesthesia, skin temperatures increased significantly (P less than 0.05 vs. saline) on the foot (great toe: +1.2 degrees C +/- 2.9 SD; little toe: +0.9 degrees C +/- 2.6) and hand (thumb: +2.0 degrees C +/- 4.0, digit 5: +2.9 degrees C +/- 4.2) but decreased after saline. Midthoracic injection also increased significantly skin temperature on the foot (great toe: +4.0 degrees C +/- 4.9; little toe: +3.6 degrees C +/- 4.8) but not on the hand. In contrast, with lumbar epidural anesthesia, skin temperature increased significantly on the foot (great toe: +8.5 degrees C +/- 2.5; little toe: +8.6 degrees C +/- 2.8) but decreased significantly on the hand (thumb: -3.1 degrees C +/- 2.1; digit 5: -2.8 degrees C +/- 2.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Epidural↗
PubMed1979

Display and visualization of three-dimensional reconstructed anatomic morphology: experience with the thorax, heart, and coronary vasculature of dogs.

A new method, termed reprojection, is used to visualize anatomic morphology contained within three-dimensional reconstructions made up of images of multiple parallel cross sections. This method involves the projection, either orthographically into a plane or radially onto a cylinder, of the volume picture elements (voxels) of the reconstruction. Orthographic reprojection images, formed by mathematically summing the magnitudes of the voxels along selected parallel paths through the reconstructed volume, are analagous to conventional radiographs formed by the passage of an X-ray beam through the volume. The reprojection image is a two-dimensional array of picture elements that is displayed on a television monitor using a digital-to-video scan converter. Also described are the techniques of noninvasive selective tissue dissolution and numerical dissection, whereby obscuring portions of the reconstructed volume are either partially "dissolved" or totally eliminated before reprojection. Utilizing these methods, anatomic information present in a three-dimensional reconstruction but not clearly seen in a reprojection image is rendered visible after removal of superposed structures. The usefulness of these methods is demonstrated utilizing three-dimensional reconstructions of the thorax, heart, and coronary arteries of dogs.

Animals↗
PubMed1989

Magnetic resonance imaging of the thorax: techniques, current applications, and future directions.

Magnetic resonance imaging (MRI) has been used extensively to evaluate the central nervous and musculoskeletal systems. MRI provides excellent contrast between normal and pathologic tissues, identifies vascular structures without the need of intravenous contrast, and is able to image in multiple planes. Until recently, physiologic motion produced artifacts that markedly limited the use of MRI in the thorax. However, with the advent of cardiac gating and respiratory motion compensation, diagnostic images can now be readily acquired. The ability to distinguish between flowing blood and adjacent tissue allows for the detection of aortic aneurysms and dissections. Prominent vessels may be differentiated from hilar adenopathy without the use of contrast agents. Preliminary experience suggests MRI may be useful in assessing central pulmonary emboli and mediastinal venous obstruction. The ready identification of flow combined with the multiplanar capability of MRI provide a means of assessing congenital abnormalities and other anatomic information. Fast scan techniques provide a dynamic means of assessing cardiac function and are sensitive to valvular stenosis and insufficiency. Combined with spin-echo techniques, areas of myocardial infarction and focal wall motion abnormalities can be detected. Currently, MRI has little application in the assessment of pulmonary nodules, bronchogenic cancer, and diffuse parenchymal disease. Sagittal MR images may more clearly show tumor extension into the axilla, brachial plexus, and spinal canal in patients with superior sulcus neoplasms. Future applications may include faster imaging techniques, blood flow measurement, detection of thrombus using phase sensitive techniques, regional perfusion, and assessment of cellular energy metabolism.

Forecasting↗
PubMed2006

Cadaver evaluation of EMG needle insertion techniques used to target muscles of the thorax.

STUDY DESIGN: Measure the accuracy of needle insertion in thoracic muscles of human cadavers. OBJECTIVES: Evaluate the effectiveness of known EMG techniques for sampling thoracic innervated muscles. SUMMARY OF BACKGROUND DATA: The evaluation of thoracic radiculopathies requires accurate electrodiagnostic techniques for evaluating the thoracic myotomes. METHODS: An American Board of Electrodiagnostic Medicine certified physician placed needles into pertinent muscles of the thorax and an anatomist serving as a blinded dissector recorded the path and accuracy of needle. RESULTS: Needle examination of thoracic muscles was as accurate as limb needle examination. No notable risks are noted in multifidus sampling. However, in the cadaver, some risks were noted in association with placements in the intercostal muscles. The target muscle was reliably sampled, but the rib or vertebral level was difficult to landmark in the cadaver. CONCLUSIONS: Needle examination of the thoracic multifidus and intercostals is reliable, although further confirmation is needed to accurately verify the appropriate vertebral or rib level being sampled.

Adult↗
PubMedDate not supplied

MRI of the brain and thorax during extracorporeal membrane oxygenation: preliminary report from a pig model.

Early diagnosis of cerebral hypoxic ischemic complications during extracorporeal membrane oxygenation (ECMO) is important to guide further treatment. However, diagnostic methods available during ECMO are limited, especially in adults and older children. Magnetic resonance imaging (MRI) is a sensitive and noninvasive method for assessment of vessel patency and brain parenchymal changes, and for measurement of brain perfusion. The use of MRI during ECMO has, to our knowledge, never been reported. We report the first animal experiment with MRI examination during ECMO. After a preliminary test with the mobile ECMO system in the MRI environment, a healthy pig was put on venoarterial ECMO, transported to the MRI department, and examined with sequences for anatomy and function of the brain and thorax. The results showed that the ECMO system was not adversely affected by the magnetic field at a distance from the camera where positioning and examination of the animal was possible. High-quality anatomical and functional images of the brain, heart, and thoracic vessels were acquired. The results suggest that MRI may be used for early diagnosis of cranial complications in patients on ECMO. MRI may also provide a useful tool for further research on flow dynamics and brain perfusion during ECMO.

Animals↗
PubMed2006

Unusual radiologic manifestations of the echinococcus infection in the thorax.

Unusual location and presentation of hydatid cyst disease in the thorax requires careful consideration with respect to clinical approach and therapy. In this pictorial essay, we present imaging findings and describe treatment of thoracic hydatid cysts in patients with lung, mediastinal, chest wall, cardiac, endobronchial, pulmonary artery, and diaphragmatic involvement. A review of the literature is also included.

Adult↗
PubMed1994

Cardiac and respiratory related electrical impedance changes in the human thorax.

Electrical impedance measurements have been made from the human trunk over the frequency range 9.6 kHz to 614 kHz. Measurements have been made from 12 normal subjects and the amplitude of the impedance changes associated with the cardiac and respiratory cycles have been recorded. It was found that the real part of the impedance fell to 64.0% of its low frequency value over the measured range of frequencies and that the changes associated with respiration fell in a similar manner. However, the cardiac related changes fell more rapidly with increasing frequency to 28.2% of the low frequency value. The origin of the measured changes is discussed with a view to understanding why the cardiac related changes fall more rapidly. It is not possible to relate in any simple way the frequency dispersion of a single component to that of the whole trunk. However, the results are consistent with the lungs being the major origin of both the cardiac and respiratory related components. The origin of the cardiac related impedance changes could be the pulsatile volume changes in the pulmonary tree. These could be shunted by nonpulsatile lung tissue that has decreasing impedance at high frequency and thus decreases the relative magnitude of the cardiac related changes. This hypothesis needs to be tested using localized measurements from the thorax and 3-D modeling of the trunk.

Adult↗
PubMed1995

Optimization of cardiac defibrillation by three-dimensional finite element modeling of the human thorax.

The goal of this study was to determine the optimal electrode placement and size to minimize myocardial damage during defibrillation while rendering refractory a critical mass of cardiac tissue of 100%. For this purpose, we developed a 3-D finite element model with 55,388 nodes, 50,913 hexahedral elements, and simulated 16 different organs and tissues, as well as the properties of the electrolyte. The model used a nonuniform mesh with an average spatial resolution of 0.8 cm in all three dimensions. To validate this model, we measured the voltage across 3-cm2 Ag-AgCl electrodes when currents of 5 mA at 50 kHz were injected into a human subject's thorax through the same electrodes. For the same electrode placements and sizes and the same injected current, the finite element analysis produced results in good agreement with the experimental data. For the optimization of defibrillation, we tested 12 different electrode placements and seven different electrode sizes. The finite element analyses showed that the anterior-posterior electrode placement and an electrode size of about 90 cm2 offered the least chance of potential myocardial damage and required a shock energy of less than 350 J for 5-ms defibrillation pulses to achieve 100% critical mass. For comparison, the average cross-sectional area of the heart is approximately 48 cm2, about half of the optimal area. A second best electrode placement was with the defibrillation electrodes on the midaxillary lines under the armpits. Although this placement had higher chances of producing cardiac damage, it required less shock energy to achieve 100% critical mass.

Computer Simulation↗
PubMed1980

Posture with elevated and extended thorax. The influence of the position on some haemodynamic and ventilatory parameters under general anaesthesia.

The effects of a change in posture from flat supine to supine with elevated and extended thorax have been investigated in 12 healthy patients under general anaesthesia prior to elective surgery on the stomach. The following parameters were measured: pulse rate, mean arterial blood pressure (MABP), central venous pressure (CVP), ventilation pressure, oesophageal pressure, and arterial oxygen and carbon dioxide tensions. Changes were measured as deviations from initial values before the change of position at 4 and 15 min after the change. One patient (8%) had a 31% fall in MABP and a 87% fall in CVP, requiring treatment outside the standard procedure, but acceptable values were obtained by simple means. Eleven patients showed only minor changes: a mean initial rise in pulse rate of 10% and a fall in CVP of 25%, after which the pulse rate returned to the initial level and the CVP remained stable. MABP was unchanged, as were ventilation pressure, oesophageal pressure and gas tensions. On the basis of reports in the literature and findings in this study, it is concluded that otherwise healthy patients tolerate the posture well, the slight risk of haemodynamic complications being outweighed by the surgical advantages. This posture should be used with caution in patients who may be haemodynamically unable to compensate.

Adult↗
PubMed1999

Defibrillation efficacy of different electrode placements in a human thorax model.

The objective of this study was to measure the defibrillation threshold (DFT) associated with different electrode placements using a three-dimensional anatomically realistic finite element model of the human thorax. Coil electrodes (Endotak DSP, model 125, Guidant/CPI) were placed in the RV apex along the lateral wall (RV), withdrawn 10 mm away from the RV apex along the lateral wall (RVprox), in the RV apex along the anterior septum (RVseptal), and in the SVC. An active pulse generator (can) was placed in the subcutaneous prepectoral space. Five electrode configurations were studied: RV-->SVC, RVprox-->SVC, RVSEPTAL-->SVC, RV-->Can, and RV-->SVC + Can. DFTs are defined as the energy required to produce a potential gradient of at least 5 V/cm in 95% of the ventricular myocardium. DFTs for RV-->SVC, RVprox-->SVC, RVseptal-->SVC, RV-->Can, and RV-->SVC + Can were 10, 16, 7, 9, and 6 J, respectively. The DFTs measured at each configuration fell within one standard deviation of the mean DFTs reported in clinical studies using the Endotak leads. The relative changes in DFT among electrode configurations also compared favorably. This computer model allows measurements of DFT or other defibrillation parameters with several different electrode configurations saving time and cost of clinical studies.

Computer Simulation↗