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Ultrasound Method (ultrasound + method)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Acute effects of caffeine and tobacco on arterial function and wave travel

EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 12 2006
J. Swampillai
Abstract Background, Caffeine and tobacco consumption are risk factors for heart failure, but their effects remain controversial. It has been hypothesized that they cause alterations in arterial stiffness and arterial wave travel which may increase ventricular loading. In this study the authors examined the influence of these widely used stimulants on wave intensity and arterial stiffness parameters using carotid wave intensity analysis. Materials and methods, A new Doppler-based ultrasound method was used to measure the acute effects of caffeine and tobacco on wave intensity in the right common carotid artery. The measurements enabled changes in arterial stiffness parameters to be recorded. Results, In 17 subjects compared with 10 controls, caffeine increased blood pressure, early systolic wave intensity and wave speed, but late-systolic wave intensity and mid-systolic reflections were unchanged. In 11 smokers studied before and after smoking one cigarette, blood pressure and arterial stiffness increased but wave intensity was unchanged. No changes were observed in the controls. Conclusions, Increased wave intensity during ejection after caffeine suggested sympathomimetic effects on the left ventricular function. Increased wave speed in the common carotid artery implied augmented central loading after caffeine, but the absence of measurable changes in local arterial stiffness in the carotid artery suggested more complex and regional effects. Cigarette smoking acutely increased local arterial stiffness in the common carotid artery. These changes can be detected using wave intensity analysis. [source]

Calibrated quantitative ultrasound imaging of skeletal muscle using backscatter analysis

MUSCLE AND NERVE, Issue 1 2008
Craig M. Zaidman MD
Abstract We evaluated the ability of an ultrasound method, which can characterize cardiac muscle pathology and has reliability across different imaging systems, to obtain calibrated quantitative estimates of backscatter of skeletal muscle. Our procedure utilized a tissue-mimicking phantom to establish a linear relationship between ultrasound grayscale and backscatter levels. We studied skeletal muscles of 82 adults: 45 controls and 37 patients with hereditary myopathies. We found that skeletal muscle ultrasound backscatter levels varied with probe orientation, age, and muscle contraction and pathology. Reliability was greater with the probe in longitudinal compared with transverse planes. Backscatter levels were higher in those >40 years of age, in muscle extension than flexion, and in myopathic patients than controls. Calibrated measurements of muscle backscatter have sensitivity and specificity in identifying and reliably measuring levels of skeletal muscle pathology. Muscle Nerve 38: 893,898, 2008 [source]

Effects of synthesis conditions on crystal morphological structures and thermal degradation behavior of hydrotalcites and flame retardant and mechanical properties of EVA/hydrotalcite blends

POLYMER COMPOSITES, Issue 2 2007
Longchao Du
The effects of synthesis methods and reaction conditions on the crystal morphological structures and thermal degradation behavior of hydrotalcites have been studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), particle size analysis (PSA), and differential thermal analysis (DTA). The flame retardant and mechanical properties of ethylene,vinyl acetate (EVA) blends with the corresponding hydrotalcites have been estimated by limiting oxygen index (LOI), UL-94, and mechanical measurements. The results from the XRD, TEM, and PSA demonstrate that the hydrotalcites synthesized by ultrasound method have larger crystal sizes and particle size distribution than those by mechanical stirring method. Higher reaction temperature, longer dripping time, and lower solution concentration can increase the crystal and particle sizes of ultrasound-synthesized hydrotalcites, whereas the longer ultrasound aging time can increase the crystal sizes and decrease the particle sizes of hydrotalcites because of the smashing conglomeration. The DTA data give a positive evidence that the hydrotalcite samples prepared by mechanical stirring method with longer alkaline dripping time have higher thermal degradation temperature than those by ultrasound method, since the ultrasound-synthesized hydrotalcites have more lattice defects than stirring-prepared hydrotalcites. The data from LOI, UL-94, and mechanical tests show that the ultrasonic-synthesized hydrotalcites have better flame retardant properties, whereas the stirring-synthesized hydrotalcites have better tensile strength in the EVA/hydrotalcite blends. POLYM. COMPOS., 28:131,138, 2007. © 2007 Society of Plastics Engineers [source]

Neonatal hip instability: results and experiences from ten years of screening with the anterior-dynamic ultrasound method

ACTA PAEDIATRICA, Issue 8 2002
JE Andersson
Aim: To record the results and experiences from a 10-y screening period with the anterior-dynamic ultrasound method for detecting neonatal hip instability. Methods: An ultrasonographic improvement of the Palmen/Barlow test was used. The screening programme included 22 047 newborns. Decisions about treatment were made solely on the ultrasound result. Results: It was found that 175 infants (7.9/1000) had at least one unstable hip,dislocated or dislocatable. Dislocated hips were found in 1.1/1000. Dislocatable hips were found in 6.8/1000 but only 1.1/1000 needed treatment. The total frequency of treatment was 2.2/1000. All cases but one were diagnosed before discharge from the maternity ward. The rate of surgery was 0.1/1000 newborns. Girls were more affected than boys, by a ratio of 3:1. Among the affected hips 64.4% were a left hip. Conclusion: Neonatal hip instability is always present at birth and can be diagnosed immediately after birth. We have no indications that instability can appear at a later stage. The anterior-dynamic ultrasound screening programme is an efficient tool to diagnose neonatal hip instability and to decide when to begin treatment. [source]