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At least 181 records · Page 10Linked to original sources

PubMed2001

Fracture repair of the distal portion of the radius by use of a condylar screw implant in an adult horse.

An 8-year-old American Quarter Horse gelding was evaluated because of an open fracture involving the left radius. The horse had fallen during training and became immediately non-weight-bearing in the left forelimb. On initial evaluation, the horse was unable to bear weight on that limb; radiography revealed a long oblique fracture of the distal metaphysis of the radius with minimal displacement of the fracture fragments. Because of the configuration of the fracture, we recommended surgical intervention with internal fixation. A condylar screw implant and 4.5-mm broad dynamic compression plate were applied to the medial and dorsolateral aspects of the radius, respectively. The horse recovered in a sling and full-limb bandage. Six months after discharge, the horse was reevaluated because of a grade 4/5 lameness in the same limb. Palpation revealed signs of severe pain over the distomedial aspect of the radius. Radiography of the left radius revealed severe osteolysis beneath the distal aspect of the condylar screw implant. Surgical removal of the medial plate was performed. Sixteen months after the initial fracture repair, the horse had returned to light training without signs of lameness. Removal of the dorsal plate may be indicated if this horse is to return to aggressive training or becomes lame in the left forelimb.

Animals↗

PubMed2005

The effect of an extended flexor carpi radialis approach on blood flow to the distal radius: a cadaveric study.

The effect of an extended flexor carpi radialis approach on the blood supply of the radius was examined in six (3 paired) fresh frozen cadaver limbs after injection with India ink and clearing using a modified Spalteholz technique. An extended flexor carpi radialis approach to the distal radius was made in the left limb in each of the three-paired limbs. The right limb served as a nonoperative control. Following perfusion of the arterial vasculature of each limb with India ink, serial transverse sections were cut and the intraosseous blood supply evaluated using a modified Spalteholz technique. Both controls and surgical specimens demonstrated complete cortical penetration from endosteal vessels in the proximal and midsections of the radius. In the distal radius, surgical specimens demonstrated reduced perfusion volarly, however there continued to be perfusion of ink through intact dorsal and ulnar metaphyseal perforating arteries. Persistent vascular perfusion to the distal radius remains through intact endosteal vessels and metaphyseal perforators of extensive surgical soft-tissue stripping.

Aged, 80 and over↗

PubMed2001

[Study on the correlation of estrogen receptor gene polymorphism to bone mineral density of radius in Chinese Han postmenopausal women in Beijing].

OBJECTIVE: To investigate the distribution of estrogen receptor (ER) gene polymorphism in postmenopausal Han women in Beijing as well as its correlation with bone mineral density (BMD) of radius. METHODS: Xba I, and Pvu II polymorphism of ER gene were studied by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 99 healthy postmenopausal Han women. BMD of distal (spongy bone) and proximal (compact bone) radius were determined by dual-energy X-ray absorptiometry (DEXA) as well. The relationship between BMD and polymorphism of ER gene was analyzed by variance analysis. RESULTS: Pvu II polymorphism of ER gene is not associated with BMD of both sites of radius (P > 0.05); while Xba I polymorphism of ER gene is significantly associated with BMD spongy and compact bone of radius (P < 0.05). Women with XX genotype have the lowest BMD T-score of -1.55 +/- 0.37 for the compact and -2.54 +/- 0.38 for the spongy, and those with xx genotype have the highest BMD T-score of -0.95 +/- 0.24 for compact and -1.74 +/- 0.16 for spongy. CONCLUSION: There is a significant correlation of Xba I polymorphism of ER gene with BMD of distal and proximal radius. It is indicated that the difference in ER genotypes among individuals might influence the development of osteoporosis.

Asian People↗

PubMed2003

[Ulnar-carpal impingement after fractures of the distal radius].

The authors describe the group of 23 patients (16 women, 7 men), who were operated during 2000-2003 on ulna-carpal impingement or the syndrome of ulna impact on the basis of "plus variant" of ulna or also "long ulna". There was a fracture of distal radius in anamnesis of all these patients. The condition was solved in 18 patients (mean age 51 years) by reducing the ulna by 4.5 cm on the average (range 2-10 mm). In five patients (mean age 49 years), the radius-ulna desis sec. Sauvé-Kapandij was performed. The results are evaluated with the time lapse of 6 months on the average (range 3-26). The resulting evaluation indicates that in all patients, who were not affected by radius-ulna arthrosis, a simple reduction of ulna resulted in an improvement of the extent of movements and improved subjective complaints. Patients with radius-ulna arthrosis, where the ulna-carpal impingement was solved by radius-ulna desis, suffer from worse long-term functional results. The authors also analyze complications of the interventions. Posttraumatic deformations in the area of distal forearm should be solved early before degenerative changes develop. The is the only way how to expect good results of the operation and favorable effect for the patient.

Adult↗

PubMed2004

Nonbridging external fixation for fractures of the distal radius.

OBJECTIVE: To assess the feasibility of using standard components from the small AO external fixator set to support fractures of the distal radius with a construct incorporating distal fixation in the periarticular radius fragment that would allow for primary mobilization of the wrist joint during fracture healing. METHODS: In a prospective pilot study of a nonbridging external fixator in early 2001, 6 consecutive cases of fracture in the distal radius presenting at a tertiary care centre, the Hamilton General Division of Hamilton Health Sciences, were compared with 6 historical controls treated with a standard bridging construct immobilizing the wrist. Both groups were or had been treated with closed reduction and external fixation of the distal radius under fluoroscopic control. Fracture alignment was measured on radiographs after healing and removal of the fixation devices; additional (secondary) outcome measures were pin-tract sepsis and implant loosening (treatment failure). RESULTS: Compared radiographically with controls, alignments after fracture healing were improved (and virtually anatomic) with use of the nonbridging external fixator. The incidence of pin-tract sepsis was similar in the 2 groups, neither of which included any treatment failures. CONCLUSIONS: Nonbridging external fixation of comminuted distal radius fractures can be accomplished safely and effectively. The results of this pilot study suggest that improved radiographic alignment may be achieved with this technique.

Early Ambulation↗

PubMed1990

Biomechanical analysis of pin placement and pin size for external fixation of distal radius fractures.

A series of biomechanical analyses were performed to explain the recent reduction in treatment-related complications of external fixation of distal radius fractures using a limited open approach for pin placement and larger 4-mm self-tapping half pins. A comparison of pull-out strength, stress concentration effect, and inherent bending strength of 3- and 4-mm half pins was performed. The effect of proximal pin placement in the radius or in the ulna and the effect of distal pin placement in four, six, or eight metacarpal cortices were determined. These analyses demonstrate that the 4-mm self-tapping half pins result in a significantly higher pull-out strength and only a small decrease in torsional load strength of the bone. They also demonstrate that proximal pin fixation in the radius produces the most stable fixation and that distal pin fixation into six metacarpal cortices produces a strong configuration that does not violate the interosseous muscles of the second intrinsic compartment. The rate of treatment-related complications in the external fixation of distal radius fractures (specifically, pin loosening, bending and breakage, fracture through pin sites, collapse at the fracture site, and intrinsic contracture) are addressed in this study. Such complications can be minimized by using 4-mm pins after central predrilling, with proximal placement in the radius and distal placement through six cortices of the bases of the second and third metacarpals.

Animals↗

PubMed1998

[Results of Kapandji-Sauvé operation after distal radius fractures].

Incongruity of the distal radioulnar joint represents a major problem following malunited fractures of the distal radius. A useful solution is the arthrodesis of the distal radioulnar joint with distal ulnar pseudarthrosis as described by Kapandji-Sauvé. The results of this procedure are presented and the indication compared to alternative treatment options discussed. Between 1991 and 1997, 19 patients were treated with a Kapandji-Sauvé procedure, for rheumatoid arthritis in seven and for a malunited fracture of the distal radius in twelve patients. All of the patients with a malunion of the distal radius were followed up 5 to 70 months postoperatively by clinical and X-ray examination. For evaluation the protocol by Martini for malunited fractures of the distal radius was used. All but one patient agreed that the operation had been beneficial and would choose to undergo the same procedure again necessary. Mean forearm rotation improved from 99 to 166 degrees. Preoperative pain was reduced in eleven patients. Two patients were completely pain-free and seven noticed pain during heavy load only. Grip strength improved postoperatively in three patients, remained unchanged in four and was diminished in three. In two patients preoperative measurements were not available. Evaluation by the Martini protocol gave three very good, four good, four fair, and one poor result. In one patient, regeneration of the ulna across the resected segment occurred necessitating a secondary excision. This resulted in a return of forearm rotation of 140 degree and good patient satisfaction. Arthrodesis of the distal radioulnar joint with distal ulnar pseudarthrosis reliably reduces pain and improves forearm rotation after malunited fractures of the distal radius. However, it cannot influence pain originating from the radiocarpal joint. Therefore, patients with advanced radiocarpal arthrosis are not suitable for the operation. We consider the procedure to be indicated when the distal radioulnar joint is compromised by the fracture itself or by posttraumatic degenerative arthrosis or when instability or subluxation of the distal radioulnar joint occurs that cannot be corrected. We have not observed persisting problems resulting from instability of the proximal ulna.

Adolescent↗

PubMed2005

Hydrodynamic radius ladders of proteins.

We introduce hydrodynamic radius ladders of proteins as a new tool to isolate and measure the role of hydrodynamic size on transport properties of proteins. Radius ladders are collections of derivatives of a protein that differ incrementally in number of polyethylene glycol (PEG) chains grafted to their surface. The addition of these chains causes the hydrodynamic size of the protein to increase. Capillary electrophoresis (CE) separates these derivatives into individual peaks or "rungs" of a ladder composed of proteins that have the same number of PEG chains, and provides a way to measure the values of hydrodynamic radius of proteins that constitute the rungs of the ladder. We demonstrate the utility of this approach by measuring the partitioning of radius ladders into polymer hydrogels. The combination of radius ladders and CE produces a large amount of internally consistent data on hydrodynamic size. This technique will have applicability to the study of the role of hydrodynamic size on transport.

Electrophoresis, Capillary↗

PubMed1979

Rat jejunum perfused in situ: effect of perfusion rate and intraluminal radius on absorption rate and effective unstirred layer thickness.

In anaesthetized rats a jejunal segment was perfused in situ varying the perfusion rate (0.1, 0.2, 0.5 ml/min) in a randomized order. The intraluminal radius of the segments was small (1.7 mm) or enlarged (3.1 mm) by increasing the intraluminal pressure. The appearance rate of butanol, antipyrine, salicylic acid, D- and L-phenylalanine but not of urea in the venous blood of the jejunal segments was increased up to 35%, when the intraluminal perfusion rate was raised from 0.1 to 0.5 ml/min. Two factors contribute to this effect: the flattening of the concentration gradient down the segment and the reduction of the effective unstirred layer thickness. The length and the intraluminal radius of the perfused segments was not altered, when the perfusion rate was varied. Therefore, a change of the absorbing area did not contribute to the increase of the absorption rate induced by the increase of the perfusion rate. In the series with small intraluminal radius the experimental data corresponded to the theoretical predictions obtained for a laminar intraluminal flow. In the segments with enlarged intraluminal radius the increase of the absorption rate by raising the perfusion rate was less than expected for a laminar flow indicating that the flow might have been turbulent. The enlargement of the intraluminal radius from 1.7 to 3.1 mm increased the absorption rate up to 100%.

Animals↗

PubMed1994

Distal radius fracture is an early sign of general osteoporosis: bone mass measurements in a population-based study.

To evaluate the bone mass by bone density measurements in patients with distal radius fracture, a prospective open case-control study was carried out in the county of Uppsala, Sweden, with population-based cases and controls. There were 111 patients with a distal radius fracture who were otherwise healthy and aged 53-76 years, together with 60 healthy controls of similar age, sex and menopausal status. The main outcome measures were bone mineral density (BMD) in the lumbar spine and hip measured with dual-energy X-ray absorptiometry, and in the (non-fractured) distal forearm determined by single-photon absorptiometry. It was found that at all measuring sites BMD was significantly lower in cases than in controls. The difference in the distal forearm was around 20% (p < 0.001) and in the spine and hip 5%-8% (p < 0.05-0.001). In the healthy subjects there were positive correlations (r = 0.39-0.65; p < 0.002) between the forearm BMD and that of both the spine and hip, whereas in the patients with distal radius fracture there was only a weak correlation between the forearm and spine BMD (r = 0.28; p < 0.05) and no association between the BMD of the forearm and hip (r < 0.01). It is concluded that patients with distal radius fracture who are otherwise healthy have a preferential bone loss at the distal forearm but also a generally low bone mass. Patients with fracture of the distal radius fracture should be considered for prophylactic measures against osteoporosis.

Age Factors↗

PubMed1999

Demonstration of two distributions of vesicle radius in the dopamine neuron of Planorbis corneus from electrochemical data.

An electrochemical model to calculate the relative size and neurotransmitter concentration of individual nerve cell vesicles is presented to examine potentially different types of vesicles in Planorbis corneus. Amperometric current transients resulting from individual exocytosis events detected from single cells contain the information necessary to quantify vesicular neurotransmitter amount and to estimate other important cellular properties such as vesicular neurotransmitter concentration and vesicle radius. Use of a simplifying assumption that the cross-sectional area of the contents of each release event is the apparent electroactive area of the electrode and that the shape of the decreasing phase of each current transient follows Cottrell-like behavior, the Cottrell equation and Faraday's law can be combined to yield expressions for relative vesicle radius and neurotransmitter concentration. This analysis has been applied to data obtained from the cell body of the giant dopamine neuron of the pond snail P. corneus. The histogram of vesicular dopamine concentration reveals a single wide distribution and the histogram of vesicle radius reveals a bimodal radius distribution. These data strongly suggest two distinct classes of vesicle radius in the P. corneus neuron lead to the bimodal distribution of amount released reported earlier.

Animals↗

PubMed1987

End-systolic radius to thickness ratio: an echocardiographic index of regional performance during reversible myocardial ischemia in the conscious dog.

Regional myocardial dysfunction induced by ischemia is associated with less thickening and a larger ventricular radius at end-systole. Thus, end-systolic radius to thickness ratio measured by echocardiography may provide an accurate index of regional left ventricular function that is totally independent of cardiac motion. To test this hypothesis, a total of 14 transient (less than or equal to 10 minutes) coronary artery occlusions (8 left anterior descending, 6 left circumflex) followed by up to 24 hours of reperfusion were performed in six chronically instrumented conscious dogs providing multiple grades of regional ventricular dysfunction. Regional myocardial thickening fraction was determined with epicardial pulsed Doppler probes and served as an independent standard for comparison with simultaneous echocardiographic measurements. End-systolic radius to thickness ratio and radial shortening fraction were derived from the two-dimensional echocardiographic short-axis view along 12 equidistant radii. In the ischemic zone, percent thickening fraction averaged 22 +/- 5% during baseline, decreased to -4 +/- 4% during occlusion with gradual return to baseline after reperfusion. End-systolic radius to thickness ratio averaged 1.39 +/- 0.25 before coronary occlusion and increased to 2.97 +/- 0.48 during occlusion with a gradual return to baseline values. A significant correlation was found between Doppler-determined thickening fraction measurements and echocardiographic end-systolic radius to thickness ratio as well as radial shortening fraction for absolute values (r = -0.83 and 0.75, respectively; n = 65) and percent change from baseline (r = -0.86 and 0.78, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1997

[Effect of ski tapering on turning radius and stress].

The first part of this paper deals with the influence of the side cut on the turn radius, which was examined by measuring the turn radius of a self-running sledge-like construction and by comparing it to Howe's prediction. The turn radius at the beginning of the turn has proved to be between 65 and 85% of the theoretically expected result. In the second part a carvers turn radius was determined and the reaction force acting on the skier was calculated. The result shows a strong reduction of the turn radius along the path which increases the load on the skier. The effect of side cut and velocity on the load was examined. Using carver skis even small changes in velocity resulted in considerable load changes.

Acceleration↗

PubMed2003

Seasonal changes in stem radius and production of new tracheids in Norway spruce.

The progress of xylem formation in Norway spruce (Picea abies (L.) Karst.) was measured during one growing season in southern Finland. Stem radius was monitored continuously with band dendrometers, and the formation of new tracheids was determined by examination of small increment cores taken twice weekly. Tracheid production started in June and ceased in August. Xylem formation was fastest in early July, when 0.75-1.25 new tracheids were formed per day. The rate of xylem formation was significantly correlated with mean daily temperature. Synchronous fluctuations in tracheid and lumen diameters were observed at the same relative positions within each annual ring, but no relationship existed between the diameters and weather variables. The timing of changes in stem radius differed from the timing of actual xylem formation. Stem radius increased in April and May, and the fastest daily increments were recorded in June. Increases in stem radius slowed in July, but small increases were measured more than a month after xylem formation had ceased. Daily changes in stem radius were correlated with daily precipitation, reflecting changes in stem water content. Therefore, dendrometers are of dubious value for measuring the timing of actual xylem formation. Small increment cores proved to be useful in assessing actual xylem formation, but the method is laborious.

Finland↗

PubMed2001

Measurement of instability growth in a magnetized Z pinch in the finite-Larmor-radius regime.

The development of the m = 0 instability in a Z pinch was followed and the measured growth rates compared with 2D MHD simulations. Where MHD is valid, the measured growth rates agree well with simulation. Where the ions are magnetized, i.e., where the ion-cyclotron frequency is smaller than the ion-collision frequency and the ratio of the ion Larmor radius to pinch radius is of the order of 0.1, the growth rate was smaller than expected by a factor of 2.5. This is as predicted by finite-Larmor-radius theory. The product of the wave number and the pinch radius was ka approximately 2pi and was the same for all conditions. Perturbations as large as 30% of the pinch radius were observed; no nonlinear saturation was evident.

Journal Article↗

PubMed2006

Simulations of the accuracy in retrieving stratospheric aerosol effective radius, composition, and loading from infrared spectral transmission measurements.

We examine the extent to which three physical aerosol parameters--effective radius, composition (sulfate weight percent), and total volume-can be determined from infrared transmission spectra. Using simulated transmission data over the range 800-4750 cm(-1) (12.5-2.1 microm) and errors taken from the infrared spectral measurements of the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument, we use optimal estimation to recover these aerosol parameters. Uncertainties in these are examined as a function of the size, composition, and loading of stratospheric aerosols and of the spectral range employed. Using the entire spectral range above, we retrieve all three parameters with a precision to within 3% if the size distribution form is known. Additional errors result, however, from an uncertainty in the size distribution width. These are small (only a few percent) for composition and total volume but are substantial (as much as 50%) for effective radius. Errors also increase substantially when the spectral range is reduced. The retrieved effective radius can have an error of 100% or greater for typical stratospheric aerosol sizes when the spectral range is restricted to the lower wavenumber part of the range. For good accuracy in effective radius, the spectral range must extend beyond approximately 3000 cm(-1). Composition and total volume are less sensitive to the spectral range than effective radius. These simulations were carried out with modeled data to test the potential accuracy of stratospheric sulfate aerosol retrievals from the Atmospheric Chemistry Experiment (ACE). Because of the limitations that result from the use of simulated data, we have tested our retrieval algorithm using ATMOS spectra in different filter regions and present here the aerosol parameters obtained.

Journal Article↗

PubMed2006

Navigation performance with a virtual auditory display: effects of beacon sound, capture radius, and practice.

OBJECTIVE: We examined whether spatialized nonspeech beacons could guide navigation and how sound timbre, waypoint capture radius, and practice affect performance. BACKGROUND: Auditory displays may assist mobility and wayfinding for those with temporary or permanent visual impairment, but they remain understudied. Previous systems have used speech-based interfaces. METHOD: Participants (108 undergraduates) navigated three maps, guided by one of three beacons (pink noise, sonar ping, or 1000-Hz pure tone) spatialized by a virtual reality engine. Dependent measures were efficiency of time and path length. RESULTS: Overall navigation was very successful, with significant effects of practice and capture radius, and interactions with beacon sound. Overshooting and subsequent hunting for waypoints was exacerbated for small radius conditions. A human-scale capture radius (1.5 m) and sonar-like beacon yielded the optimal combination for safety and efficiency. CONCLUSION: The selection of beacon sound and capture radius depend on the specific application, including whether speed of travel or adherence to path are of primary concern. Extended use affects sound preferences and quickly leads to improvements in both speed and accuracy. APPLICATION: These findings should lead to improved wayfinding systems for the visually impaired as well as for first responders (e.g., firefighters) and soldiers.

Adolescent↗

PubMed2003

[Corneal radius of curvature among people with myopia].

PURPOSE: To determine the behaviour of the radius of corneal curvature among people with myopia. MATERIAL AND METHODS: A total of 167 people with myopia (117 women and 50 men) aged 12 and 51, were examined. The average of age was 24. Routine ophthalmological examinations as well as keratometry were carried out. The data was analysed using the coefficient of rang Spearman's correlation and the coefficient of linear Pearson's correlation. RESULTS: A positive correlation was found between the length of an average of corneal curvature radius and myopia progress (P < 0.007). Any correlation between the age of the people with low, medium, and high myopia and the corneal curvature radius length was not observed. CONCLUSIONS: (1) In the course of myopia the average of corneal curvature radius is reduced. (2) The length of the average of corneal curvature radius does not depend on the age of people with myopia.

Adolescent↗