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At least 73 records · Page 4Linked to original sources

PubMed2006

Optimization of post-column reactor radius in capillary high performance liquid chromatography Effect of chromatographic column diameter and particle diameter.

A post-column reactor consisting of a simple open tube (Capillary Taylor Reactor) affects the performance of a capillary LC in two ways: stealing pressure from the column and adding band spreading. The former is a problem for very small radius reactors, while the latter shows itself for large reactor diameters. We derived an equation that defines the observed number of theoretical plates (N(obs)) taking into account the two effects stated above. Making some assumptions and asserting certain conditions led to a final equation with a limited number of variables, namely chromatographic column radius, reactor radius and chromatographic particle diameter. The assumptions and conditions are that the van Deemter equation applies, the mass transfer limitation is for intraparticle diffusion in spherical particles, the velocity is at the optimum, the analyte's retention factor, k', is zero, the post-column reactor is only long enough to allow complete mixing of reagents and analytes and the maximum operating pressure of the pumping system is used. Optimal ranges of the reactor radius (a(r)) are obtained by comparing the number of observed theoretical plates (and theoretical plates per time) with and without a reactor. Results show that the acceptable reactor radii depend on column diameter, particle diameter, and maximum available pressure. Optimal ranges of a(r) become narrower as column diameter increases, particle diameter decreases or the maximum pressure is decreased. When the available pressure is 4000 psi, a Capillary Taylor Reactor with 12 microm radius is suitable for all columns smaller than 150 microm (radius) packed with 2-5 microm particles. For 1 microm packing particles, only columns smaller than 42.5 microm (radius) can be used and the reactor radius needs to be 5 microm.

Chromatography, High Pressure Liquid↗

PubMed2004

The effects of ulcer size on the wound radius reductions and healing times in neuropathic diabetic foot ulcers.

The main problems in the treatment of diabetic foot ulcers are prolonged wound healing and not necessary amputations, which may sometimes be caused by the impression that the results of conservative treatment are somewhat unpredictable. The aim of this study was to determine the effects of ulcer size on the wound radius reduction and healing times using a previously established equation for wound healing in neuropathic diabetic foot ulcers. This prospective study evaluates wound healing in 120 diabetic patients with neuropathic foot ulcers who were grouped according to four different ulcer areas (A 100 150 200 mm (2)). Ulcer healing was assessed by planimetric measurement of the wound area every second week until wound healing. The time course of wound healing in the different groups was compared by the weekly wound radius reduction using the equation R = sqrt A/pi. The average healing time in group A was 70 (95 %-CI 64 - 77) days with a wound radius reduction of 0.42 mm/week (95 %-CI 0.28 - 0.56). In group B the average healing time was 79 (95 %-CI 75 - 82) days and the weekly wound radius reduction was 0.47 mm (95 %-CI 0.45 - 0.49). The average healing time in group C was 85 (95 %-CI 80 - 89) days with a wound radius reduction of 0.53 mm/week (95 %-CI 0.42 - 0.56). In group D the average healing time was 97 (95 %-CI 91 - 103) days. The weekly wound radius reduction was 0.57 mm (95 %-CI 0.49 - 0.81). Wound radius reductions and the time needed for healing are affected by the ulcer area, a measure of ulcer size, in neuropathic diabetic foot ulcers. The calculation of the weekly wound radius reduction for different ulcer areas may be a useful tool in daily clinical practice to identify ulcers who do not respond adequately to the treatment.

Aged↗

PubMed2006

Modeling the interferometric radius measurement using Gaussian beam propagation.

We model the interferometric radius measurement using Gaussian beam propagation to identify biases in the measurement due to using a simple geometric ray-trace model instead of the more complex Gaussian model. The radius measurement is based on using an interferometer to identify the test part's position when it is at two null locations, and the distance between the positions is an estimate of the part's radius. The null condition is observed when there is no difference in curvature between the reflected reference and the test wavefronts, and a Gaussian model will provide a first-order estimate of curvature changes due to wave propagation and therefore changes to the radius measurement. We show that the geometric ray assumption leads to radius biases (errors) that are a strong function of the test part radius and increase as the radius of the part decreases. We tested for a bias for both microscaled (<1 mm) and macroscaled parts. The bias is of the order of parts in 10(5) for micro-optics with radii a small fraction of a millimeter and much smaller for macroscaled optics. The amount of bias depends on the interferometer configuration (numerical aperture, etc.), the nominal radius of the test part, and the distances in the interferometer.

Journal Article↗

PubMed2003

Predicting the failure load of the distal radius.

The distal radius is an important site for the early detection of patients at risk for fracture. Since measuring bone strength in vivo is not possible, we evaluated which bone assessment method of the forearm would best predict failure load of the distal radius and computed a factor of risk for wrist fracture (Phi wrist). Thirty-eight cadaveric forearm specimens were measured by five different techniques to assess bone density, bone mineral content, geometry and trabecular structure at the distal forearm. The bone assessment techniques included dual-energy X-ray absorptiometry (DXA) of the radius, peripheral quantitative computed tomography (pQCT) of the 4% and 20% distal sites of the radius, DXA of the phalanges, digital X-ray radiogrammetry of the forearm (DXR-BMD), and quantitative ultrasound of the radius. The failure load of each excised radius was determined by simulating a fall on an outstretched hand. The pQCT measurements of polar stress-strain index and cortical content explained the greatest portion of variance in failure load (r2=0.82-0.85). Bone mineral content measures were generally better predictors of failure load (r2=0.53-0.85) than the corresponding volumetric or areal bone mineral density values (r2=0.22-0.69) measured by either pQCT or DXA. Multiple regression analysis showed that the addition of a bone geometry measure improved the ability of a bone density measure alone to predict failure load. There was high variability in the ability of different techniques and different variables within a given technique to predict failure load. Estimates of the factor of risk for wrist fracture (Phi wrist) revealed that the women in this study would have been likely to fracture their distal radius upon falling from a standing height (Phi wrist= 1.04), whereas the men would have likely withstood the impact without fracturing their wrist (Phi wrist= 0.79).

Absorptiometry, Photon↗

PubMed2002

Growth arrest of the distal radius following a metaphyseal fracture: case report and review of the literature.

We report a 12-year-old girl who developed growth arrest of the distal radius physis 9 months after sustaining a complete fracture of the distal radial and ulnar metaphysis with no involvement of the physis evident at time of injury. The girl sustained a fracture of the metaphysis of her right distal radius and ulna after a fall. Anterior-posterior, lateral and oblique radiographs at injury, and during subsequent healing show no evidence of the fracture involving the physis. She was treated with closed reduction and casting for 6 weeks and healed uneventfully. She returned 4 month later concerned about distal ulnar prominence. Radiographs revealed a loss of radial tilt and with suspicion of a physeal bar. Magnetic resonance imaging confirmed a physeal bar located in the dorsal radial region. A literature search of the Medline database was used to obtain prior case reports for review purpose. The patient underwent an epiphysiodesis of the distal radius and ulna along with an opening wedge osteotomy and bone grafting of the distal radius to restore radial height and inclination. She healed without complication and with restoration of the normal relationship of the distal radius and ulna. A review of the literature reveals five reported case of distal radial metaphyseal fractures not invloving the physis leading to growth arrest. By comparison, there are 31 reported cases of distal radius physeal arrest following fractures involving the physis. The physician should be aware that common distal radius metaphyseal fractures may rarely lead to growth arrest.

Child↗

PubMed2001

How do reproductive and lifestyle factors influence bone density in distal and ultradistal radius of early postmenopausal women? The Nord-Trøndelag Health Survey, Norway.

In a population-based health survey, densitometry was performed at the distal and ultradistal radius with single-energy X-ray absorptiometry. Bone mineral density (BMD) data and self-reported reproductive and lifestyle data from 1652 randomly selected peri- and postmenopausal women aged 50-59 years were analyzed. A total of 893 (54.1%) postmenopausal women reported no prior use of hormone replacement therapy (HRT) and constituted the principal group of study. These women were more frequently smokers, consumed less alcohol, more coffee and had made less use of oral contraceptives (OC) than women in the HRT group. The strongest association with both distal and ultradistal radius bone densities was found for age, weight, time since menopause and a history of bilateral oophorectomy. Among reproductive factors, nulliparous women had lower BMD than parous women; however, no linear relationship was found between parity and bone density. A weak, positive relationship was found for OC and BMD in bivariate, but not in multivariate analyses. A history of hysterectomy was positively associated with BMD, stronger at the ultradistal than distal radius. A positive relationship between alcohol consumption and BMD was found at the ultradistal radius. Present or prior smokers had lower BMD than never smokers. In the multivariate model, interaction between pack-years of smoking and daily coffee intake was observed at the distal radius, and both factors had a stronger negative influence on distal than ultradistal radius bone density. In perimenopausal women, most reproductive and lifestyle risk factors found to be associated with BMD of the radius may be explained by different levels of estrogen.

Absorptiometry, Photon↗

PubMed2004

Relationship between bone mineral density of the distal radius and ulna and fracture characteristics.

PURPOSE: This study was designed to elucidate the different decrease patterns of bone mineral density (BMD) in the distal tenth and third of the radius and ulna that influence the incidence of fractures, the fracture type, and redisplacement after closed reduction and casting. METHODS: The BMD of 1024 healthy women and 86 women treated for distal radius and ulna fracture was measured in the distal tenth and distal third zones of the radius and ulna (termed R10, R3, U10, and U3, respectively) using dual-energy x-ray absorptiometry. The BMD in the fracture group was compared with age-matched BMD in the nonfracture group. The relationship between BMD, type of fracture, and radiographic parameters (radial length, radial inclination, and palmar tilt) determined after closed reduction and at bone union were examined. RESULTS: The BMD of the distal radius in zones R10 and R3 in the fracture group were significantly lower than those in the nonfracture group among subjects older than 80 years, whereas the BMD in the U10 and U3 in the fracture group were lower than those in the nonfracture group among subjects aged 50 to 59 years. No significant difference in the mean BMD in any of the fracture group subjects was found, irrespective of the fracture pattern. A significant correlation was found between the BMD in the R10 and radial length measured at bone union and between radial length measured at bone union and RL measured after closed reduction. The radial length, radial inclination, and palmar tilt measured at bone union correlated significantly with each other. CONCLUSIONS: The BMD in the R10 and R3 are potential indicators of a distal radius fracture in women over 80 years old, whereas the U10 and U3 are indicators of an ulnar styloid fracture in women in their fifties. In addition the distal radius (R10) is an important prognostic parameter of possible deformity of the radius after closed reduction and casting.

Absorptiometry, Photon↗

PubMed2004

Simultaneous radial closing wedge and ulnar shortening osteotomies for distal radius malunion.

PURPOSE: Closing wedge osteotomies are an attractive treatment option for distal radius malunion in patients with osteopenia; however, they require an ulnar head resection to accommodate closure of corrective osteotomy and to address the issue of ulnocarpal abutment. The literature contains little information on concomitant ulnar shortening osteotomy despite a physiologic solution. We report the functional and radiographic outcomes of 5 patients treated for symptomatic distal radius malunion with simultaneous radial closing wedge and ulnar shortening osteotomies. METHODS: All 5 patients were women aged 52 to 69 years (average, 61 years). Four patients had extra-articular radius fractures with dorsal angulation (20-22 degrees ) and shortening (3-7/mm); the other had the fracture with volar angulation (24 degrees ) and shortening (11 mm). Through a volar approach an appropriate amount of bone wedge was removed from the distal radius. A small volar T-plate was used to secure the osteotomized bone fragment. Six to 11 mm of ulnar shortening osteotomy was performed by using transverse osteotomy and compression plating technique with an AO compression device. RESULTS: In all 5 wrists healing of radial and ulnar osteotomies occurred less than 3 months after surgery. There were no postsurgical complications. Postsurgical radiographs showed that the volar tilt angle of the radius was reduced to normal range (range, 8-15 degrees ) in all wrists. The ulnar variance was 0 mm in 4 wrists and 2 mm in 1 wrist. There were significant improvements in pain, function, and range of motion at an average follow-up evaluation of 17 months. The average grip strength as a percentage of the opposite side improved from 30% before to 73% after surgery. CONCLUSIONS: This study showed that closing wedge osteotomy of the radius concomitant with ulnar shortening osteotomy is technically and functionally adequate. Our procedure is indicated for patients with osteopenia for whom opening wedge osteotomy of the radius is inadequate.

Aged↗

PubMed1999

Biomechanical evaluation of wrist motor tendons after fractures of the distal radius.

We conducted a biomechanical study of changes in parameters of wrist motor tendons in fractures of the distal radius in 7 cadaveric extremities. Extra-articular distal radius fractures were simulated by distal radius osteotomy and fracture angulation was maintained by external fixators. Eight positions of the distal radius fractures were studied: dorsal angulation of 10 degrees, 20 degrees, 30 degrees, and 40 degrees and radial angulation of 5 degrees, 10 degrees, 15 degrees, and 20 degrees. Dorsal and radial angulation of the fractures were measured with respect to the shaft of the radius. Excursions of 5 principal wrist motor tendons extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, flexor carpi radialis, and flexor carpi ulnaris were recorded simultaneously with wrist joint angulation using a computer-assisted recording system. Data were collected from intact wrists and from wrists with fractures at each of 8 positions of angulation during wrist flexion and extension and radical and ulnar deviation. Moment arm of the wrist motor tendons was derived from tendon excursion and joint angulation. The results demonstrated that excursions and moment arms of principal wrist motor tendons are significantly affected by dorsal and radial angulation of distal radius fractures. Amplitude of changes in moment arms increased as the deformities became more severe. Statistical analysis revealed that dorsal angulation of 10 degrees or more significantly affected moment arms of all the prime wrist motors. Dorsal angulation of 30 degrees or 40 degrees changed the moment arms greatly. Radial angulation of 5 degrees did not affect moment arms of the tendons and angulation over 10 degrees had a statistically significant effect on the tendons. We conclude that deformities of distal radius fractures have a significant influence on the biomechanics of the wrist motors.

Aged↗

PubMed1999

[Biomechanical aspects of malunited distal radius fracture. A review of the literature].

BACKGROUND: One of the most common injuries in orthopaedics is the distal radius fracture. Malunion may lead to pain, limited motion, and loss of grip strength. Presently there is no consensus concerning the indications for corrective surgery after malunion. Studies concerning the biomechanics of the wrist in cases of malunited radius fracture can be helpful. METHOD: Analysis of the literature of the last ten years. RESULTS: In laboratory studies, malalignment of the radius caused alterations of the distal radioulnar joint (anatomically: reduction of the radioulnar contact area, disruption of the deep portion of the dorsal radioulnar ligament, tightness of the triangular fibrocartilage complex; functionally: limited forearm pronation and supination). Further alterations have been found concerning the carpal kinematics, the force transmission through the wrist, the pressure distribution on the articular surface of the radius and the median nerve. CONCLUSION: Attempts should be made to obtain an anatomic reduction of all acute distal radius fractures. Posttraumatic disability of the wrist following malunion in radius fractures should accordingly be treated by a corrective osteotomy of the radius at the original fracture site.

Biomechanical Phenomena↗

PubMed2006

Cortical bone graft and endoprosthesis in the distal radius of dogs: a biomechanical comparison of two different limb-sparing techniques.

OBJECTIVE: To compare the biomechanical properties of cortical bone and surgical steel endoprosthesis for limb-sparing surgery of the distal radius in dogs and evaluate the role of the ulna in providing stability to the reconstructed limb. STUDY DESIGN: Cadaveric biomechanical study. ANIMALS: Twelve pairs of normal canine thoracic limbs. METHODS: Paired limbs were divided into 4 groups: endoprosthesis and cortical bone graft, with and without preservation of the ulna. In each limb pair, the distal segment of the radius resected from the limb to be reconstructed with an endoprosthesis was used as the cortical bone graft in the contralateral limb. The ulna was resected en bloc with the radius and at the same level as the radial osteotomy in limbs where the ulna was not preserved. Limbs were tested in axial loading until failure. The load-deformation curve was used to acquire the biomechanical properties of each construct, which were compared using 2-way ANOVA. Failure modes were compared descriptively. RESULTS: Limbs reconstructed with the endoprosthesis had significantly greater yield load, energy at yield, and ultimate load compared with limbs reconstructed with a cortical bone graft. There were no significant differences in either energy to failure or stiffness between the 2 constructs. Preservation of the ulna did not significantly improve any of the biomechanical properties tested with either endoprosthesis or cortical bone graft constructs. The modes of failure in all 4 groups were variable and inconsistent. CONCLUSIONS: Limbs reconstructed with an endoprosthesis were biomechanically superior to limbs reconstructed with a cortical bone graft in axial loading to failure. Preservation of the ulna is not required to improve the stability in axial compression after limb-sparing surgery of the distal radius. CLINICAL RELEVANCE: The endoprosthesis may provide another option for limb-sparing surgery of the distal radius in dogs. It has potential advantages when compared with cortical bone grafts, including better biomechanical performance and resistance to implant failure in axial compression, immediate availability, and no requirement for bone banking facilities. The ulna can be resected en bloc with the radius without having a negative impact on construct stability. En bloc resection of the ulna and radius may decrease the risk of local tumor recurrence after limb-sparing surgery.

Analysis of Variance↗

PubMed2004

Ontogenetic patterns of limb loading, in vivo bone strains and growth in the goat radius.

As tetrapods increase in size and weight through ontogeny, the limb skeleton must grow to accommodate the increases in body weight and the resulting locomotor forces placed upon the limbs. No study to date, however, has examined how morphological changes in the limb skeleton during growth reflect ontogenetic patterns of limb loading and the resulting stresses and strains produced in the limbs. The goal of this study was to relate forelimb loads to in vivo bone strains in the radius of the domestic goat (Capra hircus) across a range of gaits and speeds through ontogeny while observing how the growth patterns of the bone relate to the mechanics of the limb. In vivo bone strains in the radius were recorded from two groups of juvenile goats (4 kg, 6 weeks and 9 kg, 15 weeks) and compared with previously reported strain data for the radius of adult goats. Ontogenetic strain patterns were examined in relation to peak forelimb ground reaction forces, ontogenetic scaling patterns of cross-sectional geometry and bone curvature, and percentage mineral ash content. Peak principal longitudinal tensile strains on the cranial surface and compressive strains on the caudal surface of the radius increased during ontogeny but maintained a uniform distribution, resulting in the radius being loaded primarily in bending through ontogeny. The increase in strain occurred despite uniform loading (relative to body weight) of the forelimb through ontogeny. Instead, the increase in bone strain resulted from strong negative growth allometry of the cross-sectional area (proportional to M(0.53)) and medio-lateral and cranio-caudal second moments of area (I(ML) proportional to M(1.03), I(CC) proportional to M(0.84)) of the radius and only a small increase (+2.8%) in mineral ash content. Even though bone strains increased with growth and age, strains in the younger goats were small enough to suggest that they maintain safety factors at least comparable with adults when moving at similar absolute speeds. Increased variability of loading in juvenile animals may also favor the more robust dimensions of the radius, and possibly other limb bones, early in growth.

Analysis of Variance↗

PubMed1994

[Differential treatment of fractures of the distal radius].

Treatment of distal fractures of the radius has undergone considerable change during recent years. The cause for this lies primarily in the poor results of conservative treatments. In addition to osseous instability, the fractures of the radius are frequently combined with ligamentary instability as well, thereby exceeding the ability of conservative treatment. Among the many classifications, the AO classification of these fractures has proven to be the best and most widely accepted. This classification allows the recommendation of suitable procedures of treatment. The problem with inadequately healed fractures of the radius lies in the inherent unphysiological loading of the joint in the characteristic dorsal tilted position. This leads to a pathological displacement of the radius of flexion and extension and thereby to an overloading of the dorsal joint cartilage. The shortening of the radius leads to a mechanical impingement of the triangular fibrocartilagenous complex. The Kirschner wire fixation is particularly indicated in type A and type C fractures when combined with an external fixator. Of great importance here is the crossing of the K-wires, best accomplished by inserting an additional wire in a proximal to distal direction to achieve maximal mechanical stability. Biodegradable fixation devices are not yet in widespread use, as high costs and possible foreign body reactions have prevented their acceptance. The plate osteosynthesis has its domain in the treatment of volar luxation fractures (B3) and the partially articular fractures of the radius (B2). The domain of the external fixator, on the other hand, lies in the C2 and C3 fractures in combination with the K-wire osteosynthesis. Changing the mode of treatment to a plate osteosynthesis after two to three weeks allows a functional postoperative treatment. By use of a differentiated treatment regimen, the complication rate can be significantly reduced whose cause frequently lies in repeatedly attempted repositions. Nevertheless, a rupture of the tendon of the M. extensor pollicis longus takes place in a certain percentage of cases (less than 0.2%) due to the unusual vascularization of this tendon. The dystrophy of Sudeck has become a relatively rare occurrence. A connection between a compression syndrome of the median nerve and the dystrophy of Sudeck has been discussed. The differentiated management has led to a change from a purely conservative treatment to a more varied treatment of the fractures of the distal radius. In our own patients conservative treatment was carried out in 27.5%.

Bone Wires↗

PubMed1996

Anisotropy measurements obtained by fractal analysis of trabecular bone at the calcaneus and radius.

The resistance of bone tissue is influenced not only by bone density parameters but also by bone architecture parameters, such as the microarchitecture and anisotropy of trabecular bone. We have developed and validated a fractal analysis method for studying bone microarchitecture on roentgenograms. This technique provides reproducible measurements of the fractal dimension (D) of bone, which reflects bone texture. The fractal dimension is determined in 36 different directions; the mean of these 36 values is representative of the image. A polar diagram gives the value of D according to the angle of analysis. By decomposing this diagram using polar Fourier Transform analysis, the parameters related to the shape of the polar diagram can be determined. This diagram image analysis technique has been used for other similar diagrams and applied to the results of our fractal analysis method. Diagram shape characterization may provide information on the angular distribution of results and therefore on the anisotropy of the images under study. The purpose of this study was to compare roentgenograms of the calcaneus and radius in the same subjects to determine whether texture and anisotropy parameters discriminated between these two bones. Roentgenograms of the calcaneus and radius were obtained in ten nonosteoporotic subjects. The radius had a smaller fractal dimension than the calcaneus (mean +/- standard deviation: 1.215 +/- 0.025 and 1.285 +/- 0.066, respectively; p = 0.014). Differences in the shape of the polar diagram were found between the two bones. The mean Fourier coefficient ratio C2/C4 was considerably smaller at the calcaneus (0.63 +/- 0.50) than at the radius (4.88 +/- 3.45; p = 0.005). Our method allows quantitative characterization of texture and anisotropy differences between the calcaneus and radius. The smaller fractal dimension of the radius probably reflects the simpler architecture of this non weight-bearing bone. The differences in polar diagram shape allow to evaluate anisotropy differences between the calcaneus and radius.

Adult↗

PubMed1995

The Bausch and Lomb keratometer does not measure the tangential radius of curvature.

The purpose of this research was to determine if the conventional keratometer measures tangential or sagittal radius. A Bausch and Lomb keratometer was modified to enable an assessment of vertex radius and p-value to be made on convex conicoidal buttons of known surface form. Calculation of these two parameters was achieved assuming that the keratometer was measuring tangential radius and then repeated assuming a sagittal measurement. The resulting values could then be compared with those obtained by Form Talysurf analysis and by the use of an autokeratometer designed to measure sagittal radius. There was good agreement between the three instruments when the modified Bausch and Lomb keratometer was assumed to measure sagittal radius. We conclude that the Bausch and Lomb keratometer makes a radius measurement closer to the sagittal than the tangential radius of a conicoid of revolution.

Anthropometry↗

PubMed1999

Ulnar variance and skeletal maturity of radius and ulna in female gymnasts.

UNLABELLED: It is has been suggested that repetitive loading on the distal end of the radius in elite gymnasts may lead to epiphyseal changes, a premature closure (union) of the radius growth plate, and ulnar overgrowth. PURPOSE: It is hypothesized that ulnar overgrowth in female gymnasts is associated with advanced maturity status and early onset of epiphyseal closure of the radius, and later maturity status and later onset of epiphyseal closure of the ulnar. METHODS: Posterior-anterior radiographs of 201 female gymnasts, participants of the 1987 World Championships Artistic Gymnastics, were used to measure ulnar overgrowth, to determine skeletal maturation of the hand and wrist with the Tanner-Whitehouse technique, and to determine the maturity status of the radius and ulna separately, particularly with regard to the onset of epiphyseal closure. To test the hypothesis, extreme quintiles for ulnar overgrowth were contrasted for skeletal maturation of the hand and wrist and for maturity stages of the radius and ulna as defined by the Tanner-Whitehouse criteria. RESULTS: Female gymnasts who demonstrate ulnar overgrowth are skeletally more advanced in maturity status of the entire hand-wrist compared with gymnasts who did not show ulnar overgrowth. There were, however, no differences between gymnasts in the extreme quintiles of ulnar overgrowth in the maturation of the radius, although gymnasts with ulnar overgrowth show more advanced maturity status of the ulna. CONCLUSIONS: Ulnar overgrowth is thus not apparently associated with advanced maturity of the distal radial epiphysis as defined in protocols for assessing skeletal maturity and does not apparently lead to premature epiphyseal closure of the distal radius.

Adolescent↗

PubMed1988

Piezoelectric polymer curvature sensor for measurement of regional curvature radius of LV wall.

To evaluate regional myocardial function, we developed a curvature sensor for direct and instantaneous measurement of the regional curvature radius of the LV wall. The sensor is a bimorph of two sheets of thin piezoelectric polymer film. The relation between output voltage of the sensor and the reciprocal of the known curvature radius has been shown to be linear. In anesthetized dogs, we inserted the curvature sensor into the subepimyocardium with a specially designed introducer. Special care was taken to insert it parallel to the epicardial surface. Circumferential regional curvature radius, which is defined as the reciprocal of regional curvature, showed the same phasic changes as the short-axis diameter under control conditions. Under regional ischemia caused by transient occlusion of the coronary artery, amplitude of the phasic change in regional curvature radius decreased, whereas that of the short-axis diameter did not change or slightly increased. Phasic changes in regional curvature radius cannot be estimated from short-axis diameter during regional ischemia. We calculated regional wall tension from the directly measured regional curvature radius and LV pressure and found that tension-length loop clearly differentiates between regional myocardial function under control and ischemic conditions. We have concluded that our newly developed curvature sensor is accurate, that its practical use is feasible, and that measurement of the regional curvature radius of the LV wall provides detailed and accurate information on regional shape and function of the left ventricle.

Animals↗

PubMed2005

The mechanism of in-stent restenosis in radius stent: an experimental porcine study.

BACKGROUND: We investigated the mechanism of in-stent restenosis in radius stents in comparison to balloon-expandable stent (NIR stent) in pigs, with a focus on extracellular matrix (ECM). METHODS AND RESULTS: Radius (n = 4) or NIR (n = 4) stents were implanted in the left coronary arteries of miniature pigs. Quantitative coronary ultrasound (QCU) was performed before, immediately after, and at 1 and 4 weeks after the implantation. The stented-coronary arteries were harvested at 4 weeks after the implantation followed by immunohistochemical, histological, reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR studies. In QCU, mean luminal areas at 4 weeks did not differ between both groups, whereas the mean stent area and neointimal area were significantly greater in the radius (p < 0.01). The immunohistochemical study revealed a significantly decreased number of neointimal macrophages and neovascularizations (p < 0.05, p < 0.01, respectively), and a stronger expression of tenascin-C in the radius. The histological study showed a larger ECM area and less neointimal cell density in the radius than in the NIR. The RT-PCR and real-time PCR analysis revealed an enhanced expression of tanascin-C mRNA in the radius than in the NIR. CONCLUSIONS: Increased production of ECM, especially tenascin-C, played a greater role in the neointimal formation in the radius stent than inflammation.

Animals↗