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PubMed1998

[Alternative surgical method in malalignment of healed distal radius fracture: Kapandji-Sauvé procedure].

Malunion after distal radius fracture with subluxation of the distal radioulnar joint can considerably limit the function of the hand. If the malunion cannot be eliminated by the corrective osteotomy of the radius, care must be taken not to additionally impair the stability of the wrist joint and the carpus, in the event of any necessary salvage procedure. In the Kapandji-Sauvé procedure, an arthrodesis is carried out after repositioning of the distal radioulnar joint. By segment resection of the ulnar shaft, a new joint is made to permit forearm rotation. Between 1984 and 1995, a total of 96 patients were treated with this procedure in our hospital. It was possible to re-examine 87 of those patients after an average period of 4 1/2 (1 to 11) years. The average age of the patients was 59 (14 to 72) years. In 25 cases the results were very good and in 52 cases good. In nine cases the results were poor. In one case the result was unsatisfactory.

Adolescent↗
PubMed2000

Angiographic and clinical outcome of a new self-expanding intracoronary stent (RADIUS): results from multicenter experience in Japan.

The RADIUS coronary stent featuring a multisegmented slotted tube design and self-expanding nitinol delivery system has a high radial force and flexibility, uniform expansion, and contours to the shape of the vessel. Successful stent deployment was achieved in 104 stable angina patients (106 lesions; 44% LAD, 19% circumflex, and 37% RCA). Mean minimal lumen diameter (MLD) increased from 0.77 +/- 0.46 mm to 2.88 +/- 0.61 mm and mean percent diameter stenosis (% DS) decreased from 73 +/- 14% to 6 +/- 13% immediately after the procedure. At 6-month follow-up, two patients (2%) underwent urgent target revascularization, and cerebral bleeding occurred in one patient (1%). Angiographic follow-up was performed in 94 lesions (89%) and mean MLD and mean % DS were 2.08 +/- 0.92 mm and 30% +/- 24%, respectively. Stent restenosis (>50% diameter stenosis at follow-up) was observed in 16 (17%) of all lesions. The high success rate for stent deployment, low incidence of major adverse cardiac event, and lower restenosis rate after stent implantation indicate that the RADIUS stent is useful for coronary intervention.

Adult↗
PubMed1992

Mobile surrogate mothers and the development of exploratory behavior and radius of action in infant long-tailed macaques (Macaca fascicularis).

One of the effects of rearing young monkeys on surrogate mothers is a delay in the development of exploratory behavior. An important question is which difference between mother and surrogate mother caused this delay. We hypothesized that the mothers' carrying the infant through the environment promotes the development of exploratory behavior and the radius of action of infant macques. Using surrogate mothers, we reared 9 infants in a peer group with immobile surrogates and 10 infants in another peer group with mobile surrogates. During the 3rd to the 6th month, we observed each infant for 30 min weekly, collecting observational data on several behavioral parameters and on time spent in several areas in the cage. Results showed that exploratory behavior and an increase in radius of action developed more rapidly in the mobile-reared infants.

Age Factors↗
PubMed1996

Mechanisms of retardation of rigid spherical particles with 3 to 1,085 nm radius in capillary electrophoresis, using buffered polyacrylamide (molecular weight 5 x 10(6)) solutions.

Subjecting particles in the size range of 3 to 1085 nm radius (R) to capillary electrophoresis in buffered solution of entangled uncrosslinked polyacrylamide (M(r) 5 x 10(6)), it was found that particle size-dependent retardation ("molecular sieving") becomes electric field- and particle size range-dependent once the particle size exceeds 15-20 nm in radius. The field strength dependence of the retardation coefficient [KR = d(log mobility)/ d(polymer concentration] and the positive or negative sign of dKR/dR suggest the existence of two different mechanisms of molecular sieving depending on the particle size range: particles with diameters less than the screening length (or blob size) of the polymer network are thought to penetrate into the available spaces within a discontinuous polymer network; particles with diameters larger than the screening length (or blob size) of the polymer network are thought to undergo size-dependent retardation by exerting shear stress against polymer chains, and displacing them, so as to cause local deformations in a continuous polymer network. A limit in the separating capacity of molecular sieving, due to a sharp increase in the rate of band widening with polymer concentration, was found when the value of the retardation coefficient exceeded 60 (mL/g).

Acrylic Resins↗
PubMed2001

Bone quality parameters of the distal radius as assessed by pQCT in normal and fractured women.

The aim of this study was to test the ability of some indicators of different aspects of bone quality (assessed by peripheral quantitative computed tomography in the distal radius) to discriminate between fractured and nonfractured individuals. The study compared 214 women aged 45-85 years, free of any bone-affecting treatment, of whom 107 had suffered a Colles' fracture in the previous 6 months and 107 did not. The determinations included bone tissue or mineral 'mass' indicators (trabecular, cortical and total volumetric mineral content, cortical bone area); bone 'density' estimates (trabecular, cortical and total volumetric mineral density), and the Cartesian (rectangular) and polar moments of inertia as influences of cross-sectional architecture on resistance to bending and torsional loads, respectively. The influences of body height, weight and age on the tomographic indicators were minimized by adjusting the data according to the partial coefficients of multiple stepwise regressions. The adjusted values of all the indicators were lower in fractured than in nonfractured groups. The prevalence of fractures was directly related to the actual values of the indicators, rather than the age or body habitus of the individuals. The significance of these differences between the assessed indicators decreased in the following order: trabecular 'mass' > trabecular 'density' > cortical or total 'mass' > cortical architecture > total or cortical 'density' indicators. Within the same type of bone, the tissue or mineral 'mass' indicators performed better than the 'density' indicators. The cortical bone density did not give useful information, probably because of technical difficulties. Odds-ratios and receiver-operating characteristic (ROC) analyses confirmed those features. The selected 'cut-off' values of the indicators as determined by the ROC curves (very close to those determined by the inflexion points of the logistic reression curves) may indicate reference limits to detect persons at risk of fracture according to the type of information provided by each variable. These results show that these tomographic indicators discriminate well between fractured and nonfractured individuals, and should be suitable to assess how total, cortical and trabecular bone strength in the distal radius could affect different kinds of strength regardless of the age or body habitus of the individual. Their ability to estimate fracture risk from different biomechanical points of view should be assessed by adequately designed, prospective studies.

Aged↗
PubMed1986

Exclusion of spheres by agarose gels during agarose gel electrophoresis: dependence on the sphere's radius and the gel's concentration.

Agarose gel electrophoresis of spheres (radius = R) has been used to determine the effective radius (PE) of the pores of an agarose gel (percentage of agarose in a gel = A). The value of PE at a given A was taken to be the R of the largest sphere that enters the gel. When log PE is plotted as a function of log A, the results can be represented by: PE = 118A-0.74 for 0.2 less than or equal to A less than or equal to 4.0 (PE in nm). However, the data suggest significant nonlinearity in this plot, the magnitude of the exponent of the PE vs A relationship increasing by about 20% as A increases from 0.2 to 4.0. From these data, PE's as big as 1500 nm and as small as 36 nm can be achieved with agarose gels formed with unmodified, unadulterated agarose and usable for electrophoresis.

Electrophoresis↗
PubMedDate not supplied

Artificial gravity--head movements during short-radius centrifugation: influence of cognitive effects.

Short-radius centrifugation is a potential countermeasure against the effects of prolonged weightlessness. Head movements in a rotating environment, however, induce serious side effects: inappropriate vestibular ocular reflexes (VOR), body-tilt illusions and motion sickness induced by cross-coupled accelerations on a rotating platform. These are well predicted by a semicircular canal model. The present study investigates cognitive effects on the inappropriate VOR and the illusory sensations experienced by subjects rotating on a short-radius centrifuge (SRC). Subjects (N=19) were placed supine on a rotating horizontal bed with their head at the center of rotation. To investigate the extent to which they could control their sensations voluntarily, subjects were asked alternatively to "fight" (i.e. to try to resist and suppress) those sensations, or to "go" with (i.e. try to enhance or, at least, acquiesce in) them. The only significant effect on the VOR of this cognitive intervention was to diminish the time constant characterizing the decay of the nystagmus in subjects who had performed the "go" (rather than the "fight") trials. However, illusory sensations, as measured by reported subjective intensities, were significantly less intense during the "fight" than during the "go" trials. These measurements also verified an asymmetry in illusory sensation known from earlier experiments: the illusory sensations are greater when the head is rotated from right ear down (RED) to nose up (NU) posture than from NU to RED. The subjects habituated, modestly, to the rotation between their first and second sequences of trials, but showed no better (or worse) suppression of illusory sensations thereafter. No significant difference in habituation was observed between the "fight" and "go" trials.

Adaptation, Physiological↗
PubMed2004

A dynamic wicking technique for determining the effective pore radius of pregelatinized starch sheets.

A dynamic wicking technique is employed for the first time for the determination of the effective mean pore radius of a thin-layer porous food: drum dried pregelatinized starch sheets. The technique consists of measuring the penetration rate of various n-alkanes in the porous matrix of the starch sheets and using this data to calculate the effective pore radius via the Washburn equation. Pore sizes in the order of a few nanometers have been determined in the starch sheets depending on the drum dryer's operating variables (drum rotation speed, steam pressure and starch feed concentration). The conditions for the application of the technique in porous foods are discussed as compared to the conditions for single capillaries and inorganic porous material measured in other studies.

Chemical Phenomena↗
PubMed2003

Hydrodynamic radius of fractal clusters.

The Kirkwood-Riseman theory has been used to derive an analytical formula for the evaluation of the hydrodynamic radii of fractal clusters. The proposed relation is based on knowledge of the particle-particle correlation function and can be applied to clusters containing any number of particles larger than 4. The calculated values of the hydrodynamic radius are compared with the results of other theoretical approaches proposed in the literature, as well as several experimental data. Finally, the developed relation has been used in connection with a population balance equation model that computes the clusters' mass distribution to estimate the average hydrodynamic radius for a population of fractal clusters of different sizes. The obtained results have been compared to suitable experimental data for a silica colloidal suspension aggregating under reaction-limited conditions.

Journal Article↗
PubMed2004

Osteonecrosis of the trapezium treated with a vascularized distal radius bone graft.

A 20-year-old man presented with early stage osteonecrosis of the trapezium, diagnosed by magnetic resonance imaging. A vascularized distal radius bone graft was performed, with good clinical and radiologic results over a 1-year follow-up period. The authors believe that a vascularized distal radius bone graft is an ideal treatment for early stage carpal bone necrosis.

Adult↗
PubMed2004

Ionic charge, radius, and potential control root/soil concentration ratios of fifty cationic elements in the organic horizon of a beech (Fagus sylvatica) forest podzol.

The root/organic soil concentration ratio; R/S) of 50 cationic mineral elements was related to their ionic properties, including ionic radius (r), ionic charge (z), and ionic potential (z/r or z2/r). The materials studied were ectomycorrhizal beech (Fagus sylvatica L.) roots and their almost purely organic soil substrate, the O-horizon (mor; raw humus) of a Podzol in South Sweden, developed in a site which has been untouched by forestry or other mechanical disturbance since at least 50 years and located in an area with no local sources of pollution. Elements determined by ICP-AES were aluminium, barium, calcium, iron, potassium, magnesium, manganese, sodium and strontium. Determined by ICP-MS were silver, beryllium, bismuth, cadmium, cerium, cobalt, chromium, caesium, copper, dysprosium, erbium, europium, gallium, gadolinium, hafnium, mercury, holmium, indium, lanthanum, lithium, lutetium, niobium, neodymium, nickel, lead, praseodymium, rubidium, scandium, samarium, tin, terbium, thorium, titanium, thallium, thulium, uranium, vanadium, yttrium, ytterbium, zinc and zirconium. The R/S ratios were most clearly related to the ionic potential of the cationic elements studied, which accounted for approximately 60% of the variability in R/S among elements. The ionic charge of an element was more important than the ionic radius. Elements with high ionic charge had low R/S ratios and vice versa. No clear differences in R/S between essential and non-essential plant nutrients were observed, especially when ions of similar charge were compared.

Cations↗
PubMed1991

Size separation of polystyrene sulfate particles (189 to 1085 nm radius) in solutions of methyl-hydroxypropyl-cellulose of different chain lengths.

Polystyrene sulfate particles of 189 to 1,085 nm radius are retarded in their electrophoretic migration in solutions of methyl-hydroxypropyl-cellulose (4,000 and 15,000 cP viscosity for a 2% solution). The retardation is proportional to polymer concentration and increases inversely with particle size. This suggests a separation mechanism based on size-dependent exclusion from the polymer network, as found previously in other liquid polymer media. In the size range of approximately 200 to 600 nm radius, the 4,000 cP polymer exhibits a steeper decrease of retardation with particle size than the 15,000 cP polymer, but fails to exhibit any size dependent retardation beyond that range.

Cholic Acids↗
PubMed1969

Exclusion of protein from high polymer media. I. Derivation of probability distribution for the number of fiber centers within any sphere of radius r.

Ogston's (1958) fiber model based on Poisson's distribution function gives the average number of fibers making contact and no contact inside a sphere of radius r. The probability of penetration of spherical particles within a fibrous network was derived from the moment generating function [Formula: see text] A is the number of particles that intrude into a sphere of radious r. alpha(mu) is the probability that a particle, whose center is mu units away from the origin, intrudes into a sphere of radius r. A has a Poisson distribution with a mean value E(A) = 4pinualpha(mu)mu(2)dmu. The theoretical derivation of the distribution function of A gives Ogston's fiber model.

Biological Transport↗
PubMed1991

Effective pore radius of the gramicidin channel. Electrostatic energies of ions calculated by a three-dielectric model.

Electrostatic calculation of the gramicidin channel is performed on the basis of a three-dielectric model in which the peptide backbone of the channel is added as a third dielectric region to the conventional two-dielectric channel model (whose pore radius is often referred to as the effective pore radius reff). A basic principle for calculating electrostatic fields in three-dielectric models is introduced. It is shown that the gramicidin channel has no unique value of reff. The reff with respect to the "self-image energy" (i.e., the image energy in the presence of a single ion) is 2.6-2.7 A, slightly depending upon the position of the ion (the least-square value over the whole length of the pore is 2.6 A). In contrast, the reff with respect to the electric potential due to an ion (and hence the reff with respect to the interaction energy between two ions) is dependent upon the distance s of separation; it ranges from 2.6 to greater than 5 A, increasing with an increase in s. However, for the purpose of rough estimation, the reff with respect to the self-image energy can also be used in calculating the electric potential and the interaction energy, because the error introduced by this approximation is an overestimation of the order of 30% at most. It is also shown that the apparent dielectric constant for the interaction between two charges depends markedly upon the positions of the charges. In the course of this study, the dielectric constant and polarizability of the peptide backbone in the beta-sheet structure is estimated to be 10 and 8.22 A3.

Electrochemistry↗
PubMed1997

Synchronized changing of transinterface pressure, bubble radius and surface tension: a unique feature of lung surfactant.

The pulsating bubble surfactometer has been commonly used to measure the minimum surface tension of lung surfactant. The complexity of the original transinterface pressure tracings and its possible physiological meanings remain undefined. In the present study, we compared surface properties between calf lung surfactant extract (CLSE) and Tween 20, a nonionic surfactant, with the pulsating bubble surfactometer. A synchronized change between transinterface pressure (P) and bubble radius (R) was observed when CLSE was tested. Mathematical analysis and computer simulation indicate that this is due to the extremely potent surface tension lowering and adjusting abilities, which allows the surface tension to decrease towards zero at the end of compression and increase towards a high surface tension during re-expansion. In contrast, a time delay between P and R was observed when Tween 20 was assessed. Surface tension adjusting ability was shown only at concentrations below or around the critical micelle concentration (cmc) of Tween 20. Surface tension became unchangeable when concentrations were further increased, suggesting amphipathic molecules were saturated on the interface. The synchronization of transinterface pressure, alveolar radius and surface tension may play an important role in maintaining the pulmonary compliance in vivo. This unique feature, observed at concentrations several orders above the cmc of phospholipids, suggests that the structure of lung surfactant at the air-liquid interface differs from that of Tween 20, a monolayer of free amphipathic molecules.

Chemical Phenomena↗
PubMed1998

The influence of screw torque, object radius of curvature, mode of bone plate application and bone plate design on bone-plate interface mechanics.

Using Fuji Prescale Pressure Sensitive Film we evaluated the influence of screw torque, object radius of curvature, mode of bone plate application (compression or neutral loading) and bone plate design on bone-plate interface mechanics. Testing was performed using 4.5 mm and 3.5 mm dynamic compression (DC) (stainless steel) and limited contact-dynamic compression (LC-DC) plates (titanium). Plexiglass tubing, having different radii of curvature, was used to simulate bone but having more uniform geometric and structural properties. With the film interposed between the bone plate and the plexiglass, bone plates were applied at predetermined levels of screw torque. The resultant image was digitized and then underwent computer-assisted analysis to yield the interface contact area (%) and the average force (in Newtons N) between the bone plate and the object to which it was applied. In any given object, screw torque had the most significant influence on both interface contact area (P = 0.0001) and average force (P = 0.0001) at the interface. The bone plates responded differently to dynamization. The DC plate, when applied in compression loading mode, was lifted off the object between the two central screws when compared to the same plate applied in neutral loading mode (P = 0.0001). Conversely, in the LC-DC plate, an increase in the overall interface contact area was observed when applied in compression loading mode (P = 0.0002). At a given level of applied screw torque, the object radius of curvature appeared to be a major determining factor for interface contact area and average force (P = 0.0001, P = 0.0001). We conclude that variables other than bone plate design also influence the interface contact area and average force between a bone plate and object to which it is applied.

Biomechanical Phenomena↗
PubMed2006

[Trans-styloid and intrafocal pinning for extra-articular extension fractures of the distal radius: prospective randomized postoperative comparison with simple intra-focal pinning].

PURPOSE OF THE STUDY: Intra-focal pinning as described by Kapandji in 1976 is generally standard treatment of fractures of the distal radius with posterior displacement. This technique, based on the bench effect of pinning on the posterior and radial cortexes has certain limitations in the event of major posterior comminution. In order to improve stability, other authors have proposed a modification of the Kapandji technique, replacing the lateral intra-focal pin with a direct trans-styloid pin. The purpose of this prospective radiographic study was to determine whether the modified Kapandji method improves the quality of postoperative reduction and provides a gain in stability. MATERIAL AND METHODS: This prospective radiographic study included 85 patients. The first group, composed of 41 patients, was treated with the standard intra-focal pinning using one or two dorsal pins and one lateral pin (group K). The second group of 44 patients was treated with one or two intra-focal pins and one lateral transfocal pin (group KM). The postoperative care was the same for the two groups. Clinical and radiographic assessment (lateral and AP views) was performed at day 21, at day 45 after removal of the pins, and at last follow-up. Two operators working independently from the surgeons measured the orientation of the radial surface on the lateral and AP views and the radioulnar variance at day 0, 21, 45 and last follow-up. RESULTS: Group K included 38 patients, mean age 57 years, and group KM 40 patients, mean age 53 years. Seven patients were lost to follow-up. The two groups were comparable regarding age, gender, type of lesion. The postoperative assessment showed radial inclination of 19.3 degrees on the AP view and 3 degrees on the lateral view with 6.6 degrees radiolulnar variance for the K group. The corresponding values were 22.2 degrees , 5.3 degrees and 12.2 degrees for the KM group. Postoperatively, there was a significant difference between the groups for radial glenoid on the AP view (p=0.004) and radiolulnar variance (p<0.0001) but there were no differences on the lateral view. At day 45 postop, mean values were 17.3 degrees AP and 1.1 degrees lateral for radial inclination and 2.2 degrees for radioulnar variance in the K group with 21 degrees , 4.7 degrees and 10 degrees in the KM group. There was a difference in group K for values measured on day 0 and day 45. There was no significant difference between the values on day 0 and day 45 for the KM group. DISCUSSION AND CONCLUSION: The purpose of this radiological assessment was to evaluate the efficacy of replacing the lateral intra-focal pin with a lateral transfocal pin in terms of primary stability of extra-articular fractures of the distal radius with posterior displacement. The results appear to show that this technique provides more sustained reduction during the first six weeks, particularly concerning radioulnar variance and radial glenoid inclination on the AP view, objectives needed for good clinical outcome. It also enables a notable improvement in postoperative stability while preserving the advantages of an easily reproducible minimally destructive percutaneous technique.

Adult↗
PubMedDate not supplied

Artificial gravity: head movements during short-radius centrifugation.

Short-radius centrifugation is a potential countermeasure to long-term weightlessness. Unfortunately, head movements in a rotating environment induce serious discomfort, non-compensatory vestibulo-ocular reflexes, and subjective illusions of body tilt. In two experiments we investigated the effects of pitch and yaw head movements in participants placed supine on a rotating bed with their head at the center of rotation, feet at the rim. The vast majority of participants experienced motion sickness, inappropriate vertical nystagmus and illusory tilt and roll as predicted by a semicircular canal model. However, a small but significant number of the 28 participants experienced tilt in the predicted plane but in the opposite direction. Heart rate was elevated following one-second duration head turns. Significant adaptation occurred following a series of head turns in the light. Vertical nystagmus, motion sickness and illusory tilt all decreased with adaptation. Consequences for artificial gravity produced by short-radius centrifuges as a countermeasure are discussed. Grant numbers: NCC 9-58.

Adaptation, Physiological↗