Ultrasound Localization of Nitinol Wire of Sub-Wavelength Dimension.

Goal: To enhance endovascular navigation using surgical guidewires and the use of ionizing radiation, we demonstrate a method for ultrasonic localization of wires with diameters less than the wavelength of ultrasound in the medium. Methods: Nitinol wires with diameters ranging from 50 µm to 250 µm were imaged ultrasonically in a 0.25-in-diameter water-filled tube in a gelatin medium. Imaging frequencies were 5 MHz, 7.5 MHZ, and 10 MHz. Results: For the full range of diameters traversing the phantom, the wires were localized successfully via visual inspection of both regular and difference ultrasound images. Similarly, two convolutional neural networks were trained, and both achieved an accuracy of over 95%. Conclusions: Wires with diameters as small as 50 µm were localized successfully in a water-based gelatin phantom, indicating the potential use of ultrasound to enhance endovascular navigation and surgical treatment.

Physical demands associated with right-angle direct-current power-tools: An evaluation of current technology.

The purpose of this work was to evaluate the physical demands associated with three direct current powered right-angle power tool tightening strategies at various fastener-location-orientations, target torques and joint-hardness. Physical demands were measured using surface electromyography, handle force and upper body kinematics. Results identified TurboTight®, a rapid and short duration fastening strategy, to produce lower handle force impulse, less joint angle displacement, and lower EMG magnitudes when compared to the longer duration fastening strategies tested. The reduced magnitudes associated with TurboTight®, independent of fastener-location-orientations, target torques and joint-hardness, indicate a lower physical demand on power tool operators, providing a significant ergonomic benefit when compared to the slower fastening strategies.

Combined effect of hyperuricemia and overweight/obesity on the prevalence of hypertension among US adults: result from the National Health and Nutrition Examination Survey.

Hypertension is a large and growing public health problem worldwide. Hyperuricemia and overweight/obesity are two of the most important risk factors for hypertension. However, their combined effect on the risk of hypertension is not known. Participants aged 20 years and older from the National Health and Nutrition Examination Survey from 1999-2012 were used to evaluate the separate and combined effects of hyperuricemia and overweight/obesity on the risk of prevalent hypertension among different race, gender and age groups. Participants (31,473) were used to estimate separate and combined effects on the prevalence of hypertension. The overall prevalence of hypertension among adults with a combination of hyperuricemia and overweight/obesity (50.2%, 95% confidence interval (CI) 48.3-52.1%) was significantly higher than separate hyperuricemia (41.7%, 95% CI 37.2-46.2%) and overweight/obesity (30.6%, 95% CI 29.5-31.8%). The magnitude of odds ratio (OR) from the combination of hyperuricemia and overweight/obesity (OR=4.53, 95% CI 4.05-5.07) was significantly higher than both hyperuricemia (OR=2.62, 95% CI 2.07-3.32) and overweight/obesity (OR=2.08, 95% CI 1.89-2.30). Combined effect of hyperuricemia and overweight/obesity on the risk of hypertension is much stronger than any separate one. These data can provide important information for identification of target populations for future intervention and patient management.

Effects of temperature, salinity and body size on routine metabolism of coastal largemouth bass Micropterus salmoides.

Routine metabolism (i.e. standard metabolism plus a low level of activity) of coastal largemouth bass Micropterus salmoides from Mobile-Tensaw Delta, AL, U.S.A. was examined as a function of temperature (15, 20, 25 and 30° C), salinity (0, 4, 8 and 12) and body mass (range 24-886 g) using flow-through respirometry. Functionally, a cubic relationship best described the effect of salinity on respiration; the magnitude of these effects increased with temperature and body mass. The best model predicted that specific respiration (mg O(2) g(-1) h(-1)) at temperatures >20° C was lowest at salinities of 0·0 and 9·7, and elevated at 3·2 and 12·0; salinity had little to no effect at temperatures ≤20° C. Respiration increased exponentially with temperature, but when compared with previously published respiration rates for M. salmoides from northern latitudes, predicted respiration was higher at cool temperatures and lower at high temperatures. The reduced energetic cost near the isosmotic level (i.e. c. 9) may be an adaptive mechanism to tolerate periods of moderate salinity levels and may help explain why M. salmoides do not flee an area in response to increased salinity. Further, these results suggest that salinity has high energetic costs for coastal populations of M. salmoides and may contribute to the observed slow growth and small maximum size within coastal systems relative to inland freshwater populations.

Pseudosyndactyly and musculoskeletal contractures in inherited epidermolysis bullosa: experience of the National Epidermolysis Bullosa Registry, 1986-2002.

Mitten deformities of the hands and feet occur in nearly every patient with the most severe subtype (Hallopeau-Siemens) of recessive dystrophic epidermolysis bullosa, and in at least 40-50% of all other recessive dystrophic epidermolysis bullosa patients. Smaller numbers of patients with dominant dystrophic, junctional, and simplex types of epidermolysis bullosa are also at risk of this complication. Surgical intervention is commonly performed to correct these deformities, but recurrence and the need for repeated surgery are common. Higher numbers of epidermolysis bullosa patients also develop musculoskeletal contractures in other anatomic sites, further impairing overall function. Lifetable analyses not only better project the cumulative risk of mitten deformities and other contractures but also emphasize the need for early surveillance and intervention, since both of these musculoskeletal complications may occur within the first year of life.

Metabolic response of forearm muscle to graded exercise in type II diabetes mellitus: effect of endurance training.

In this study, 31P nuclear magnetic resonance spectroscopy was used to monitor muscle metabolism in Type II diabetic subjects (n = 10) during an incremental exercise test. Also the exercise responses of diabetic subjects (n = 4) following submaximal endurance training were assessed and compared to healthy controls (n = 5). Responses to incremental exercise in the diabetic subjects were consistent over time despite minor fluctuations in metabolic control. In the diabetic and control groups, after 12 weeks of training the forearm flexor muscles, power output at the intracellular threshold of acidosis (IT) increased (p < .01) similarly: T0 versus T12: 0.90 +/- 0.09 versus 1.20 +/- 0.13 and 1.03 +/- 0.07 versus 1.22 +/- 0.10 W, respectively. Minimum intracellular pH reached at peak exercise was unchanged after training. The control group, however, became more acidic versus the diabetic group (p < .05) in response to progressive exercise. This difference was maintained over time. Endurance training elicited similar adaptations in forearm muscles of Type II diabetic and control subjects, although there were differences between the two groups in intracellular pH during exercise.

A Monte Carlo investigation of artifacts caused by liver uptake in single-photon emission computed tomography perfusion imaging with technetium 99m-labeled agents.

BACKGROUND: Significant hepatobiliary accumulation of technetium 99m-labeled cardiac perfusion agents has been shown to cause alterations in the apparent localization of the agents in the cardiac walls. A Monte Carlo study was conducted to investigate the hypothesis that the cardiac count changes are due to the inconsistencies in the projection data input to reconstruction, and that correction of the causes of these inconsistencies before reconstruction, or including knowledge of the physics underlying them in the reconstruction algorithm, would virtually eliminate these artifacts. METHODS AND RESULTS: The SIMIND Monte Carlo package was used to simulate 64 x 64 pixel projection images at 128 angles of the three-dimensional mathematical cardiac-torso (MCAT) phantom. Simulations were made of (1) a point source in the liver, (2) cardiac activity only, and (3) hepatic activity only. The planar projections and reconstructed point spread functions (PSFs) of the point source in the liver were investigated to study the nature of the inconsistencies introduced into the projections by imaging, and how these affect the distribution of counts in the reconstructed slices. Bull's eye polar maps of the counts at the center of the left ventricular wall of filtered back-projection (FBP) and maximum-likelihood expectation-maximization (MLEM) reconstructions of projections with solely cardiac activity, and with cardiac activity plus hepatic activity scaled to have twice the cardiac concentration, were compared to determine the magnitude and location of apparent changes in cardiac activity when hepatic activity is present. Separate simulations were made to allow the investigation of stationary spatial resolution, distance-dependent spatial resolution, attenuation, and scatter. The point source projections showed significant inconsistencies as a function of projection angle with the largest effect being caused by attenuation. When consistent projections were simulated, no significant impact of hepatic activity on cardiac counts was noted with FBP, or 100 iterations of MLEM. With inconsistent projections, reconstruction of 180 degrees resulted in greater apparent cardiac count losses than did 360 degrees reconstruction for both FBP and MLEM. The incorporation of attenuation correction in MLEM reconstruction reduced the changes in cardiac counts to that seen in simulations in which attenuation was not included, but resulted in increased apparent localization of activity in the posterior wall of the left ventricle when scatter was present in the simulated images. CONCLUSIONS: The apparent alterations in cardiac counts when significant hepatic localization is present is due to the inconsistency of the projections inherent in imaging. Prior correction of these, or accounting for them in the reconstruction algorithm, will virtually eliminate them as causes of artifactual changes in localization. Attenuation correction and scatter correction are both required to overcome the major sources of apparent count changes in the heart associated with hepatic uptake.

Mechanical ventilation innovations: the manufacturer's perspective.

Manufacturers develop products that fit the corporate vision and maximize their return on investment. The expense and time required by the FDA regulatory approval process have a negative impact on product innovation. I propose the following approach: Reduce the amount of documentation required for a PMA or 510(k). Reduce approval times through cooperative interaction among manufacturers, clinicians, and the FDA throughout the product-development process. Allow independent agencies to provide product approvals. Efficacy assessment guidelines should be a function of the level of risk and the claims made for the marked device.

Collimator optimization for lesion detection incorporating prior information about lesion size.

A Bayesian estimator has been developed as a paradigm for human observer performance in detecting lesions of unknown size in a uniform noisy background. The Bayesian observer used knowledge of the range of possible lesion sizes as a prior; its predictions agreed well with the results of a six-observer perceptual study. The average human response to changes in collimator resolution, as measured by the detectability index, dA, was tracked by the Bayesian detector's signal-to-noise ratio (SNR) somewhat better than by two other estimation models based, respectively, on lesser and greater degrees of lesion size uncertainty. As the range of possible lesion sizes increased, the Bayesian detector's SNR decreased and the optimal collimator resolution shifted towards better resolution. An analytic approximation for the variance of lesion activity estimates (which included the same prior) was shown to predict the variance of the Bayesian estimator over a wide range of collimator resolution values. Because the bias of the Bayesian estimator was small (< 1%), the analytic variance estimate permitted a rapid and convenient prediction of the Bayesian detection SNR. This calculation was then used to optimize the geometric parameters of a two-layer tungsten collimator being constructed from crossed grids for a new imaging detector. A Monte Carlo program was first run to estimate all contributions to the radial point-spread function for collimators of differing tungsten contents and spatial resolution values, imaging 140-keV photons emitted from the center of a 15-cm-diameter, water-filled attenuator. The optimal collimator design for detecting lesions with unknown diameters in the range 2.5-7.5 mm yielded a system resolution of approximately 8.5-mm FWHM, a geometric collimator efficiency of 1.21 x 10(-4), and a single-septum penetration probability of 1%.

Ambient pressure air/oxygen blender.

This article presents a unique air/oxygen mixing device specifically designed for respiratory therapy applications where compressed air is not available. The need for such a device has increased drastically over recent years because of the increasing number of ventilator-dependent patients being cared for in private homes, which often lack facilities such as pressurized air. This pneumatically driven blender utilizes a specialized poppet-seat configuration that proportionally adjusts the gas flow area, in response to the ventilator demand, without altering the set air and oxygen percentage mixtures. A prototype of the device was designed and constructed. Tests producing favourable blending accuracy and pressure drop results are presented.

Improving the pneumatic nebulizer by shaping the discharge of the capillary wick.

The theory and function of nebulizers is discussed and their performance parameters are reviewed. The possibility of adjusting the wick-draw and atomization by altering the geometry at the top of the capillary tube is considered. A visual experiment using film as the data collection medium was performed, and the results support the hypothesis that the nebulizer's performance can be improved by adjusting the tube's configuration. Further study is suggested that will complement this preliminary qualitative study.

Purification of a Na+/K+ ATPase inhibitor from borderline hypertensives' plasma.

Increasing experimental evidences suggest an involvement of an endogenous Na+/K+ ATPase inhibitor in regulating water and electrolytes balance as well as in the pathogenesis of hypertension. However, conflicting results on the nature and the chemical structure of this substance still make it difficult to understand exactly its physiological mechanism of action. In the present study an attempt was made to purify a Na+/K+ ATPase inhibitor from hypertensives' plasma by solid phase extraction followed by 2 HPLC steps using reverse and normal phase columns. The fractions, from both columns, were able to inhibit Na+/K+ ATPase, 3H-ouabain binding to enzyme, ouabain sensitive 86Rb uptake and pNPPase activity in a manner not affected by boiling. Ultrafiltration experiments demonstrate that inhibitory activity is largely due to a low-molecular weight substance. These findings seem to confirm the presence in hypertensives plasma of a Na+/K+ ATPase inhibitor with some similarities with ouabain.

Skin blood flow from gas transport: helium xenon and laser Doppler compared.

A study was designed to compare three independent measures of cutaneous blood flow in normal healthy volunteers: xenon-133 washout, helium flux, and laser velocimetry. All measurements were confined to the volar aspect of the forearm. In a large group of subjects we found that helium flux through intact skin changes nonlinearly with the controlled local skin temperature whereas helium flux through stripped skin, which is directly proportional to skin blood flow, changes linearly with cutaneous temperature over the range 33 degrees to 42 degrees. In a second group of six volunteers we compared helium flux through stripped skin to xenon-133 washout (intact skin) at a skin temperature of 33 degrees, and we found an essentially linear relationship between helium flux and xenon measured blood flow. In a third group of subjects we compared helium flux blood flow (stripped skin) to laser doppler velocimetric (LDV) measurements (intact skin) at adjacent skin sites and found a nonlinear increase in the LDV skin blood flow compared to that determined by helium over the same temperature range. A possible explanation for the nonlinear increases of helium flux through intact skin and of LDV output with increasing local skin temperature is that they reflect more than a change in blood flow. They may also reflect physical changes in the stratum corneum, which alters its diffusional resistance to gas flux and its optical characteristics.

Reverse redistribution phenomenon in thallium-201 stress tests: angiographic correlation and clinical significance.

The reverse redistribution phenomenon (RR) with the apparent worsening of a stress-induced defect or appearance of a new area of relative hypoperfusion does not always indicate coronary artery disease as previously suggested. RR does not correlate closely with the degree of coronary artery disease, nor with the location of the stenosis. Multiple mechanisms are hypothesized wherein the "defect" may be located in the best or worst perfused area.

Plantar fascitis--early blood pool images in diagnosis of inflammatory process.

Bone scintigraphy is of diagnostic value in stress fractures where radiography may not be helpful. Obtaining early blood pool images during scintigraphy for suspected stress fractures may help to identify soft tissue inflammation (plantar fascitis) when delayed images are normal.

Laminectomy: effects on postoperative technetium and gallium scintigraphy.

Bone scans using Tc-99m diphosphonate were found to become abnormal within 2 weeks after laminectomy in less than half of patients regardless of the extent of the operation. The degree of new uptake equaled that of the sacroiliac joints in only one of 19 patients with a normal preoperative scan. However, the Ga-67 citrate scan usually became abnormal (89%) postoperatively. Thus the Tc-99m bone scan may be helpful in detecting postoperative infection.

A wide spectrum of resistance to pyrethroid insecticides in Musca domestica.

Selection of a strain of house flies with the pyrethroid bioresmethrin has resulted in a wide range of cross resistance to 15 other pyrethroid insecticides.