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PubMed1996

[Algodystrophy after distal radius fractures].

Algodystrophy is a severe complication of distal radius fractures; its incidence balances from 0.02% to 37% reported from various papers. In order to ascertain its incidence and clinical picture, the following features in 100 patients 2-4 months after distal radius fracture were examined: pain in the hand, swelling, vasomotor and sudomotor instability, stiffness, trophic changes, shoulder complaints and changes on X-ray picture; the presence and intensity of each feature were noticed. There were 87 female and 13 male patients, aged from 36 to 88 years (average 60.6 years) in the group; 79% of patients complained of pain in affected hand (spontaneous or after loading) and 20% complained of pain and limitation of movement in the shoulder joint. Algodystrophy, diagnosed by the presence of at least 4 strongly expressed features was noted in 14% of patients. The syndrome developed more frequently in women than in men, in patients with displaced and manipulated fractures (particularly with fragmentation of the epiphysis) and in individuals wit poorly reduced fractures. The most specific for algodystrophy features were: deficiency of finger flexion greater than 3 cm, severe spontaneous pain, severe swelling and permanent redness of the hand; the author suggests, that algodystrophy after distal radius fracture is far more common condition than it is generally believed.

Adult↗

PubMed1997

[Evaluation of mineral density in the distal radius during the course of rheumatoid arthritis].

Rheumatoid arthritis (RA) of progressive systemic disease predisposing for osteoporosis. Inflammatory process, applied treatment as well as considerably impared efficiency of motor organ create conditions for osteoporosis. The changes of bone mineral density in RA were assessed in 50 patients treated for various form of RA, at the Rheumatological and Rehabilitation Hospital in Cracow. The age of patients ranged from 21-79 yrs: the mean age was 50 years. The group consisted of 46 (92%) females and 4 (8%) males. Apart from standard clinical examinations there was assessed in all cases mineral density in distal radius using Osteometer DTX 100. Mineral density BMD was estimated in distal and ultradistal region of radius. All patients were qualified into 4 groups depending on the stage of radiological changes according to Steinbrocker. Group I included 16%, group II-30%, group III-30%, and IV-24% of patients. Steroid therapy was applied in 20 (40%) cases. The results showed progressive decrease of mineral density BMD in distal radius in patients with advanced RA. It was also observed that in RA patients mineral density defect occurs earlier in trabecular than in cortical bone.

Adult↗

PubMed2002

Monte Carlo study of cycloamylose: chain conformation, radius of gyration, and diffusion coefficient.

Cyclic (1 --> 4)-alpha-D-glucan chains with or without excluded volume have been collected from a huge number (about 10(7)) of linear amylosic chains generated by the Monte Carlo method with a conformational energy map for maltose, and their mean-square radii of gyration and translational diffusion coefficients D (based on the Kirkwood formula) have been computed as functions of x (the number of glucose residues in a range from 7 to 300) and the excluded-volume strength represented by the effective hard-core radius. Both /x and D in the unperturbed state weakly oscillate for x < 30 and the helical nature of amylose appears more pronouncedly in cyclic chains than in linear chains. As x increases, these properties approach the values expected for Gaussian rings. Though excluded-volume effects on them are always larger in cycloamylose than in the corresponding linear amylose, the ratios of and the hydrodynamic radius of the former to the respective properties of the latter in good solvents can be slightly lower than or comparable to the (asymptotic) Gaussian-chain values when x is not sufficiently large. An interpolation expression is constructed for the relation between the gyration-radius expansion factors for linear and cyclic chains from the present Monte Carlo data and the early proposed asymptotic relation with the aid of the first-order perturbation theories.

Carbohydrate Conformation↗

PubMed1996

Determination of peptide dissociation constants and Stokes radius at different protonation stages by capillary electrophoresis.

Peptide electrophoretic mobility measured by capillary zone electrophoresis can be regarded as deriving from the mean of mobilities of different protonated forms, each one participating according to its charge. Stokes radius and relative percentage. The percentage is a function of the peptide dissociation constant and solution pH. Therefore, mobility modifications due to pH variations can be related to peptide dissociation constant, charge, and Stokes radius throughout general binding equations. Thus, not only can peptide dissociation constants be measured, but information about Stokes radius modifications linked to proton loss can also be obtained with picomoles of peptide.

Adrenocorticotropic Hormone↗

PubMed2006

Molecular surface generation using a variable-radius solvent probe.

Protein-ligand binding occurs through interactions at the molecular surface. Hence, a proper description of this surface is essential to our understanding of the process of molecular recognition. Recent studies have noted the inadequacy of using a fixed 1.4 A solvent probe radius to generate the molecular surface. This assumes that water molecules approach all surface atoms at an equal distance irrespective of polarity, which is not the case. To adequately model the protein-water boundary requires that the solvent probe radius change according to the polarity of its contacting atoms, smaller near polar atoms and larger near apolar atoms. To our knowledge, no method currently exists to generate the molecular surface of a protein in this manner. Using a modification of the marching tetrahedra algorithm, we present a method to generate molecular surfaces using a variable radius solvent probe. The resulting surface lacks many of the unrealistic small crevices in nonpolar regions that are found when utilizing an invariant 1.4 A solvent probe, while maintaining the fine detail of the surface at polar regions. On application of the method on a test set of 20 protein structures taken from the Protein Data Bank (PDB), we also find far fewer empty unsolvated cavities that are present when using only a 1.4 A solvent probe, while the majority of solvated and polar cavities is retained. This suggests that the majority of empty cavities previously observed in protein structures might simply be artifacts of the surfacing method. We also find that the variable probe surface can have significant effects on electrostatic calculations by generating a better tuned description of the protein-water boundary. We also examined the binding interfaces of a diverse set of 55 protein-protein complexes. We find that using a variable probe results in an increase in perceived shape complementarity at these sites compared to using a 1.4 A solvent probe. The molecular volume and surface area are geometric values that determine various important properties for macromolecules, and the altered description afforded by a variable solvent probe molecular surface can have significant implications in protein recognition, energetics, folding, and stability calculations.

Entropy↗

PubMed2005

Effect of post-excitation radius on ion abundance, mass measurement accuracy, and isotopic distributions in Fourier transform ion cyclotron resonance mass spectrometry.

We report an evaluation of a modern Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) instrument to determine the general trend of post-excitation radius on total ion abundance, mass measurement accuracy, and isotopic distributions for internally calibrated mass spectra. The optimum post-excitation radius was determined using total ion abundance, mass measurement accuracy (MMA), and isotope ratios. However, despite the utility of internal calibration for achieving ultimate MMA, the internal calibrant ions were insufficient for compensating for sub-optimum ICR cell conditions. The findings presented herein underscore the importance of determining the optimal post-excitation radius in FT-ICR-MS to achieve high ion abundance (low limits of detection), high MMA, and valid isotopic distributions.

Bradykinin↗

PubMed1997

Analysis of Nitrogen Adsorption Isotherms for a Series of Porous Silicas with Uniform and Cylindrical Pores: A New Method of Calculating Pore Size Distribution of Pore Radius 1-2 nm

Two kinds of the porous silicas with uniform and cylindrical pores were prepared from calcined Na4SiO4 and cationic surfactants ([C16H33N(CH3)3]Cl and [C18H37N(CH3)3]Br). In this paper, we call these porous silicas PS-C16 and PS-C18. PS-C16 was calcined in vacuo at 873-1273 K in order to prepare a series of porous silicas having different pore sizes. All nitrogen adsorption isotherms for a series of the porous silicas show no hysteresis in the adsorption and desorption branches. The nitrogen adsorption isotherms were analyzed by the t method, and the pore surface area (Sp), the pore volume (Vp), and the core volume (Vc) were determined. The pore radius (rp), the core radius (rc), and the adsorbed thickness on the pore wall (tpore) were computed from the measured values of Sp, Vp, and Vc. We can determine the relationship between the Polanyi adsorption potential and the core radius in the range of rc = 0.6-1.2 nm. On the basis of the present data, we propose a new method of calculating the pore size distribution in the range of rp = 1-2 nm.

Journal Article↗

PubMed1997

Attritional flexor tendon ruptures after a malunited intra-articular fracture of the distal radius.

Rupture of the flexor tendon following Colles fracture is uncommon. In all reported cases it occurred as a complication of an extra-articular, displaced fracture of the distal radius. We report a case in which flexor tendon rupture occurred 30 years after a comminuted intra-articular fracture of the distal end of the radius. There have been no reports of delayed flexor tendon rupture after an intra-articular fracture of the distal radius in young adults.

Colles' Fracture↗

PubMed2003

[Results of palmar T-plate osteosynthesis in unstable fractures of the distal radius].

For unstable fractures of the distal radius, the dorsal plate requires exposure of the fragments, frequently spongioplasty, and usually removal of the implant later on. However, with the palmar approach for the reconstruction of the articular surface and restoration can easily be achieved with the T-plate. In the Traumatology Department of the University at Göttingen, we have gained experience in the treatment with the palmar T-plate in more than 400 patients. In a prospective study, we investigated the functional and radiological results after palmar T-plate osteosynthesis in Colles fractures. From September 1994 to December 1998 we treated 200 patients with the palmar T-plate (AO, 3.5 mm, titanium). 166 patients (83%), mean age 59 years, could be followed up >18 months. AO classification: A2:10, A3:45, B1:18, B2:10, C1:24, C2:40, C3:19. We compared group 1 (younger than 60 years, n=88) vs group 2 (older than 60 years, n=78). The patients' evaluation of the usability of the hand was normal in 56% and in 26,5% slightly reduced. 12,5% felt handicapped and 5% felt severely handicapped. 5% of the patients changed the domain hand, 15,4% at least partly. Function according to Lidström: 23% excellent, 58% good, 15% fair and 4% poor results. Radiological results according to Lidström were excellent and good in 88,3% and fair in 11,7%. Gartland and Werley score was excellent in 66%, good in 24%, fair in 6% and poor in 4%. There was no significant difference between group 1 and group 2 in the age-depending results. The secondary dislocation, the average dorsal tilt was 3 degrees, the mean shortening of the radius was 1,5 mm. We saw steps in the joint surface from 0,5-1 mm in 10%. An algodystrophy occurred in 5%. 12% of the patients complained of limited sensitive irritations of the medianus nerve most likely originating in the formerly used approach close to the medianus nerve. After changing this approach, we saw no irritation of the Nervus medianus among 50 patients so far. Evaluation of the functional and radiological investigations: The palmar T-plate has produced reliable and good results in the treatment of unstable distal fractures of the radius without angle-stable screws up to now. This type of osteosynthesis is stable for exercise and ensures early mobilization with good functional results even in elderly patients.

Adolescent↗

PubMed1986

Determination of a particle's radius by two-dimensional agarose gel electrophoresis.

Electrophoresis in an agarose gel dilute enough to be almost nonretarding, followed by electrophoresis in an orthogonal direction into a more concentrated agarose gel, has been developed as a procedure to determine the radius of spherical particles. Unlike procedures of unidirectional electrophoresis in a single gel, the above procedure can be used to compare the radii of particles that differ in solid-support-free electrophoretic mobility. Accuracy of 0.3 nm has been achieved with particles 30 nm in radius. It was found that the apparent radius of the spherical capsid of bacteriophage P22 decreased by 3% during elevated temperature-induced ejection of DNA from the capsid. Though originally designed for use with multimolecular particles, the procedure described here should also be useful with monomolecular particles.

Bacteriophages↗

PubMed1988

Stokes radius determination of radioiodinated polypeptide hormones by gel filtration.

A simple technique for determination of the molecular (Stokes) radius of radioiodinated proteins was developed using the same column and chromatographic conditions employed in routine radioimmunoassay tracer purification. The calibration curve for five radioiodinated standard proteins presented a highly significant correlation (r = -0.996; P less than 0.001) and allowed precise molecular radius determination for labeled human growth hormone (hGH), luteotropin (hLH), follicle-stimulating hormone (hFSH), thyrotropin (hTSH), prolactin (hPRL), and corticotropin (hACTH), enabling detection of differences of the order of +/- 3%. The validity of the method was verified by determining the molecular radius of hGH in both "cold" (unlabeled standards and unknowns) and "hot" (radioiodinated standards and unknowns) systems. The technique can be applied in a very simple manner, requiring just one simple additional calibration run before Sephadex G-100 tracer purification. Furthermore, it can be applied to any protein, even when only extremely limited amounts are available. Since the standards and unknowns are labeled and chromatographed under identical conditions, potential common alterations of the molecule due to oxidation, iodine incorporation, tracer-carrier interactions, etc., are automatically corrected for.

Chromatography, Gel↗

PubMed1991

Volumetric properties of polyols (ethylene glycol, glycerol, meso-erythritol, xylitol and mannitol) in relation to their membrane permeability: group additivity and estimation of the maximum radius of their molecules.

The relationship of molecular volume and maximum molecular radii to the ability of some polyols, ethylene glycol, glycerol and meso-erythritol, to permeate the Chara cell membrane and to the inability of one of the polyols, mannitol, to permeate the Chara cell membrane, was examined by measuring the partial molar volumes of the polyols, Vm(2). Analysis of Vm(2) at infinite dilution showed that group additivity is maintained for all the groups, i.e., CH2OH and CHOH, of the polyols tested. However, as the permeability and impermeability could not be related to the geometrical properties of the polyol molecules based only on the thermodynamic quantities, molecular models of the polyol molecules were constructed using the CPK(Corey-Pauling Koltum) molecular model, which is designed to have the van der Waals radius of 1 A equivalent to 1.25 cm. The results showed that the maximum radius of the water-filled pore (hydrophilic channel) should be 3.2-3.3 A, and the longer the axial length and maximum radius of the polyol molecule, the lesser was its permeative ability. All the experimental and analytical results and inferences support the idea that water molecules pass across the cell membrane through a narrow pore in a single-file fashion.

Ampholyte Mixtures↗

PubMed1983

Effect of zinc on the Stokes' radius of metallothionein.

Apothionein was prepared from rat liver metallothionein-II. To this, zinc, as zinc acetate, was re-added in a stepwise fashion to yield a series of complexes with ratios of metal to protein varying from 1:1 to 7:1. The Stokes' radius of the apoprotein and each zinc-metallothionein complex was then determined by gel filtration. A plot of atoms Zn/mol metallothionein versus Stokes' radius yielded a sigmoid curve, with values for Stokes' radius ranging from 20.8 A for the apoprotein 15.4 A for the fully saturated zinc complex.

Animals↗

PubMed1994

Factors affecting functional outcome of displaced intra-articular distal radius fractures.

Open reduction and internal fixation is often required in comminuted, displaced intra-articular fractures of the distal radius when closed manipulation has failed to restore articular congruity. Results of surgical stabilization and articular reconstruction of these injuries are reviewed in this retrospective study of 49 patients with 52 displaced, intra-articular distal radius fractures. Forty-three patients with a mean age of 37 years (range, 17-79 years) were available for evaluation. The mean follow-up time was 38 months (range, 22-69 months). When rated by the system proposed by the Association for the Study of Internal Fixation (ASIF), 19 were ASIF type C2 and 21 were ASIF type C3. An injury score system based on the initial injury x-ray films was used to classify severely comminuted intra-articular fractures and to identify those associated with carpal injury. Postoperative fracture alignment, articular congruity, and radial length were significantly improved following surgery. Grip strength averaged 69 +/- 22% of the contralateral side, and range of motion averaged 75 +/- 18% of the contralateral side after surgery. A combined outcome rating system that included grip strength, range of motion, and pain relief averaged 76 +/- 19% of the contralateral side. Using regression analysis, a significant decrease was found in the combined rating with more severe fracture patterns as defined by the ASIF system, Malone classification, and the injury score system. The injury score system presented here and, in particular, the number of fracture fragments correlated most closely with the outcome of all classification systems examined. Operative treatment of complex distal radius fractures with reconstruction of articular congruity with internal fixation and/or external fixation can significantly improve functional outcome. The degree to which articular step-off, gap between fragments, and radial shortening are improved by surgery is strongly correlated with improved outcome, even when the results are corrected for severity of initial injury, whereas correction of radial tilt or dorsal tilt did not correlate with improved outcome.

Adult↗

PubMed1994

Simultaneous proximal row carpectomy and radius to distal carpal row arthrodesis.

We assessed the functional results of simultaneous proximal carpal carpectomy and radius to distal carpal row arthrodesis. A retrospective review of patients undergoing wrist arthrodesis for degenerative joint disease was performed. Patients with rheumatoid arthritis or spastic hemiplegia were excluded. Simultaneous proximal row carpectomy and radius to distal carpal row arthrodesis was performed in 38 patients using AO plates and 3.5 mm diameter screws. The mean follow-up time was 16 months, the fusion rate was 100%, and the average grip strength was 24 kg force or 79% of the contralateral hand measured at 10 degrees wrist extension. Patients with three or more screws placed in the metacarpal had significantly more plate-related complications and a higher rate of plate removal than those with two screws distally. Simultaneous proximal row carpectomy and radius to distal carpal row arthrodesis did not decrease the postoperative grip strength.

Adult↗

PubMed2004

Radius of curvature and asphericity of the anterior and posterior surface of human cadaver crystalline lenses.

The purpose of this study was to measure the shape of the anterior and posterior surface of human cadaver lenses in situ using a corneal topography system. Measurements were performed on 13 pairs of eyes using the PAR Corneal Topography System (PAR-CTS). The age of the donors ranged from 46 to 93 years, with an average age of 76.4 years. Anterior lens topography was measured after excision of the cornea and iris. Posterior lens topography was measured after sectioning the posterior segment and adherent vitreous. The PAR-CTS files providing raw surface height were exported for analysis. In each surface, 18 meridians separated by 10 degrees were fitted using conic sections to obtain values of the apical radius of curvature (R) and shape factor (p). The average apical radius of curvature and asphericity were R=10.15+/-1.39mm and p=4.27+/-1.39 for the anterior surface and R=-6.25+/-0.79mm and p=-0.64+/-1.85 for the posterior surface. A significant variation of the radius of curvature and shape factor as a function of the meridian angle (lens astigmatism) was found in some lenses. Contrary to previous findings, the anterior lens surface was found to steepen toward the periphery.

Aged↗

PubMed1988

Electrostatic radius of the gramicidin channel determined from voltage dependence of H+ ion conductance.

The results of Decker and Levitt (1987) suggest that the conductance of H+ ion through the gramicidin channel is limited primarily by diffusion in the bulk solution at the channel mouth. It is assumed in this paper that the H+ conductance is 100% diffusion limited. This means that all the factors that influence the H+ flux are external to the channel and are presumed to be known. In particular, the diffusion coefficient of H+ in this region is assumed to be equal to the bulk solution value and the only force acting on the ion is that due to the applied voltage. A model of the H+ flux is derived, based on the Nernst-Planck equation. It has three adjustable parameters: the electrostatic radius, the capture distance, and the radius of the H+ ion. The acceptable range of the parameters was determined by comparing the predictions of the model with the experimental measurements of the H+ conductance at pH 3.75. The best fit was obtained for an electrostatic radius in the range 2.3-2.7 A. This is in good agreement with earlier predictions (2.5 A) based on the assumption that the dielectric constant of the channel water is equal to that of bulk water. The addition of 1 M choline Cl- (an impermeant) increases the H+ current at low voltage and decreases it at high voltage. The increase can be explained by the small surface charge that results from the separation of charge produced by exclusion of the large choline cation (relative to Cl-) from the membrane surface. The decrease at high voltages can be accounted for by the change in the profile of the applied potential produced by the increase in ionic strength.

Diffusion↗

PubMed1996

DNA binding to mica correlates with cationic radius: assay by atomic force microscopy.

In buffers containing selected transition metal salts, DNA binds to mica tightly enough to be directly imaged in the buffer in the atomic force microscope (AFM, also known as scanning force microscope). The binding of DNA to mica, as measured by AFM-imaging, is correlated with the radius of the transition metal cation. The transition metal cations that effectively bind DNA to mica are Ni(II), Co(II), and Zn(II), which have ionic radii from 0.69 to 0.74 A. In Mn(II), ionic radius 0.82 A, DNA binds weakly to mica. In Cd(II) and Hg(II), respective ionic radii of 0.97 and 1.1 A, DNA does not bind to mica well enough to be imaged with the AFM. These results may to relate to how large a cation can fit into the cavities above the recessed hydroxyl groups in the mica lattice, although hypotheses based on hydrated ionic radii cannot be ruled out. The dependence of DNA binding on the concentrations of the cations Ni(II), Co(II), or Zn(II) shows maximal DNA binding at approximately 1-mM cation. Mg(II) does not bind DNA tightly enough to mica for AFM imaging. Mg(II) is a Group 2 cation with an ionic radius similar to that of Ni(II). Ni(II), Co(II), and Zn(II) have anomalously high enthalpies of hydration that may relate to their ability to bind DNA to mica. This AFM assay for DNA binding to mica has potential applications for assaying the binding of other polymers to mica and other flat surfaces.

Adsorption↗