Hiroyuki Sugiyama

Brown-Sèquard syndrome produced by cervical disc herniation: report of two cases and review of the literature

BACKGROUND CONTEXTnBrown-Sèquard syndrome is most commonly seen with spinal trauma and extramedullary spinal neoplasm. A herniated cervical disc has rarely been considered to be a cause of Brown-Sèquard syndrome.nnnPURPOSEnTo report and discuss two cases of Brown-Sèquard syndrome produced by herniated cervical disc.nnnSTUDY DESIGN/SETTINGnCase studies in Japan.nnnPATIENT SAMPLEnThe first patient was a 64-year-old man who presented with right leg weakness and diminished sensation to pain and temperature in the left side below the T4 dermatome. The second patient was a 39-year-old man who presented with right-sided weakness and diminished sensation to pain and temperature in the left side below the T6 dermatome.nnnOUTCOME MEASURESnAmerican Spinal Cord Injury Association (ASIA) impairment scale (only our cases).nnnMETHODSnThese patients were diagnosed to have Brown-Sèquard syndrome produced by herniated cervical disc. Anterior cervical discectomy with fusion was performed for these patients.nnnRESULTSnThese cases revealed contralateral deficit in sensation of pain and temperature of more than a few levels below the cord compression, and showed paracentral protruded disc in magnetic resonance images and cervical spinal stenosis in cervical spine X-rays. Postoperatively, motor and sensory function of these patients returned to normal.nnnCONCLUSIONSnCharacteristic finding in discogenic Brown-Sèquard syndrome are contralateral deficit in sensation of pain and temperature of more below than a few levels below the cord compression and paracentral protruded disc with cervical spinal stenosis. Outcomes are favorable in rapid diagnosis by magnetic resonance images and performance of anterior approach.

Effects of testosterone, hypophysectomy and growth hormone treatment on clofibrate induction of peroxisomal β-oxidation in female rat liver

Induction of peroxisomal beta-oxidation by clofibrate under altered hormonal states was investigated in female rat liver. Treatment of rats with clofibric acid (CPIB) caused a significant increase in hepatic peroxisomal beta-oxidation, with female rats being less responsive than males (4.2- vs 12.2-fold increase). However, testosterone treatment following ovariectomy of female rats resulted in an enhanced response to CPIB, giving an induction (11.7-fold) comparable to that seen in male rats. Hypophysectomy of female rats also enhanced the induction (8.2-fold compared with 5.1-fold), suggesting a suppressive effect of a pituitary-dependent factor on CPIB induction of peroxisomal beta-oxidation. Continuous infusion of growth hormone to the hypophysectomized female rats suppressed the enhanced induction nearly to the initial level (6.1-fold). The stimulatory effects of testosterone and hypophysectomy on the enzyme induction were additive. These findings suggest the involvement of growth hormone, as well as male sex hormone, in regulating the responsiveness to CPIB induction of peroxisomal beta-oxidation in rat liver.

Coupled Deformation Modes in the Large Deformation Finite-Element Analysis: Problem Definition

In the classical formulations of beam problems, the beam cross section is assumed to remain rigid when the beam deforms. In Euler-Bernoulli beam theory, the rigid cross section remains perpendicular to the beam centerline; while in the more general Timoshenko beam theory the rigid cross section is permitted to rotate due to the shear deformation, and as a result, the cross section can have an arbitrary rotation with respect to the beam centerline. In more general beam models as the ones based on the absolute nodal coordinate formulation (ANCF), the cross section is allowed to deform and it is no longer treated as a rigid surface. These more general models lead to new geometric terms that do not appear in the classical formulations of beams. Some of these geometric terms are the result of the coupling between the deformation of the cross section and other modes of deformations such as bending and they lead to a new set of modes referred to in this paper as the ANCF-coupled deformation modes. The effect of the ANCF-coupled deformation modes can be significant in the case of very flexible structures. In this investigation, three different large deformation dynamic beam models are discussed and compared in order to investigate the effect of the ANCF-coupled deformation modes. The three methods differ in the way the beam elastic forces are calculated. The first method is based on a general continuum mechanics approach that leads to a model that includes the ANCF-coupled deformation modes; while the second method is based on the elastic line approach that systematically eliminates these modes. The ANCF-coupled deformation modes eliminated in the elastic line approach are identified and the effect of such deformation modes on the efficiency and accuracy of the numerical solution is discussed. The third large deformation beam model discussed in this investigation is based on the Hellinger-Reissner principle that can be used to eliminate the shear locking encountered in some beam models. Numerical examples are presented in order to demonstrate the use and compare the results of the three different beam formulations. It is shown that while the effect of the ANCF-coupled deformation modes is not significant in very stiff and moderately stiff structures, the effect of these modes can not be neglected in the case of very flexible structures.

Gradient Deficient Curved Beam Element Using the Absolute Nodal Coordinate Formulation

In this investigation, a gradient deficient beam element of the absolute nodal coordinate formulation is generalized to a curved beam for the analysis of multibody systems, and the performance of the proposed element is discussed by comparing with the fully parametrized curved beam element and the classical large displacement beam element with incremental solution procedures. Strain components are defined with respect to the initially curved configuration and described by the arc-length coordinate. The Green strain is used for the longitudinal stretch, while the material measure of curvature is used for bending. It is shown that strains of the curved beam can be expressed with respect to those defined in the element coordinate system using the gradient transformation, and the effect of strains at the initially curved configuration is eliminated using one-dimensional Almansi strain. This property can be effectively used with a nonincremental solution procedure employed for the absolute nodal coordinate formulation. Several numerical examples are presented in order to demonstrate the performance of the gradient deficient curved beam element developed in this investigation. It is shown that the use of the proposed element leads to better element convergence as compared with the fully parametrized element and the classical large displacement beam element with incremental solution procedures.

Specific binding of dehydroepiandrosterone sulfate to rat liver cytosol: A possible association with peroxisomal enzyme induction

Incubation of [3H]dehydroepiandrosterone sulfate (DHEAS) with rat liver cytosol demonstrated its specific binding with a dissociation constant of 72 +/- 14 nM and a maximal binding capacity of 312 +/- 105 fmol/mg cytosol protein. The binding correlated with the amount of cytosol protein, and depended on time, temperature and pH, with equilibrium being reached after 6 h at 0 degrees C and pH 7.5. Boiling or treatment of the cytosol with proteases or sulfhydryl-blocking reagents affected the binding. The apparent molecular mass of the binding entity was estimated to be 160-230 kDa by HPLC gel filtration. In competitive binding studies, free steroids, including dehydroepiandrosterone (DHEA), sulfatase substrates and ligands of organic anion binders such as ligandin and fatty acid binding protein, had no effect on the [3H]DHEAS binding. Peroxisome proliferators also had no effect, except Wy-14,643. Competition with various steroids related to DHEAS revealed strict structural requirements for DHEAS binding, in which epiandrosterone sulfate was almost as effective as unlabeled DHEAS in inhibiting [3H]DHEAS binding. These findings indicated the presence of a binding protein highly specific to DHEAS in rat liver cytosol. The DHEAS binding in liver cytosol was 2-fold higher in male than in female rats. The cytosolic DHEAS binding was highest in the liver, followed by the kidney and heart. The possibility of association between the DHEAS binding and DHEA induction of peroxisomal beta-oxidation is discussed.

On the Contact Search Algorithms for Wheel/Rail Contact Problems

In this investigation, contact search algorithms for the analysis of wheel/rail contact problems are discussed, and the on-line and off-line hybrid contact search method is developed for multibody railroad vehicle dynamics simulations using the elastic contact formulation. In the hybrid algorithm developed in this investigation, the off-line search that can be effectively used for the tread contact is switched to the on-line search when the contact point is jumped to the flange region. In the two-point contact scenarios encountered in curve negotiations, the on-line search is used for both tread and flange contacts to determine the two-point contact configuration. By so doing, contact points on the flange region given by the off-line tabular search are never used, but rather used as an initial estimate for the online iterative procedure for improving the numerical convergence. Furthermore, the continual on-line detection of the second point of contact is replaced with a simple table look-up. It is demonstrated by several numerical examples that include flange climb and curve negotiation scenarios that the proposed hybrid contact search algorithm can be effectively used for modeling wheel/rail contacts in the analysis of general multibody railroad vehicle dynamics.

Wheel∕Rail Two-Point Contact Geometry With Back-of-Flange Contact

In this investigation, a numerical procedure that can be used for the analysis of a wheel and rail contact geometry is developed using the constraint contact formulation. The locations of contact points are determined for given lateral and yaw displacements of a wheelset when one-point contact is considered for each wheel, while these two displacements are no longer independent when the two-point contact occurs. A systematic procedure for predicting the flange, as well as the back-of-flange contact points, is developed and used for the two-point contact geometry analysis of a wheel and rail. Numerical results that involve tread, flange, and back-of-flange contacts are presented in order to demonstrate the use of the contact algorithm developed in this investigation. In particular, the back-of-flange contact is discussed for assessing contact configurations of a wheel and a grooved rail in light rail vehicle applications.

Analysis of Wheel/Rail Contact Geometry on Railroad Turnout Using Longitudinal Interpolation of Rail Profiles

In this investigation, a numerical procedure that can be used for the analysis of wheel/rail two-point contact geometries in turnout sections is developed. In turnout section, the tongue rail changes its shape along the track. Cross-sectional shapes of the tongue rail, therefore, need to be generated by interpolations along the track and these profiles are used to determine the location of contact points for the given location of wheelset. Several numerical examples are presented in order to demonstrate the use of the procedure developed in this investigation and the effect of wheel profiles on contact geometry in turnout section is discussed.

Dynamics of Independently Rotating Wheel System in the Analysis of Multibody Railroad Vehicles

In this investigation, dynamic characteristics of independently rotating wheel systems are discussed. To this end, a multibody independently rotating wheelset (IRW) model is developed using the method of velocity transformation. The linear stability analysis of a two-axle IRW truck is performed, the hunting stability and vibration characteristics of IRW truck are investigated, and the results are compared with those obtained using the multibody dynamics model. Good agreement is obtained in hunting frequencies and critical speeds. It is shown using the linear IRW equations that since a constant forward speed is assumed for IRW, the longitudinal slip can occur due to the change in the wheel rolling radius. This leads to longitudinal creep forces even in the case of IRW and it contributes to a coupling of the lateral, yaw, and pitch motions of IRW. Furthermore, it is observed in several numerical examples that, due to small self-centering forces of IRW, continuous flange contact occurs on tangent track, while in curve negotiation, flange contacts on outer wheel of the front axle, as well as that on inner wheel of the rear axle, occur. Such an effect can be more significant when sharp curve negotiation is considered as encountered in light rail vehicle applications.

Photoaffinity labeling of peroxisome proliferator binding proteins in rat hepatocytes; dehydroepiandrosterone sulfate- and bezafibrate-binding proteins

To detect the cellular sites which directly interact with peroxisome proliferators (PPs) and mediate their inducing effect on peroxisomal enzymes in rat hepatocytes, two kinds of radiolabeled ligands, AD12 (7alpha-N-(4-azido-2-hydroxy-5-iodo[125I]benzyl)-aminomethyl-5-and rostene-3beta-ol-17-one-O-3-sulfate) and BZ5 (2-[p-[2-(4-azido-3,5-diiodo[125I]benzamido-2-hydroxy)ethyl]phenoxy] -2-methylpropionic acid), were developed for photoaffinity labeling. These compounds were derivatives of dehydroepiandrosterone sulfate (DHEAS) and bezafibrate, respectively, with an azido group as the photoreactive functional group. Upon UV-irradiation following incubation with rat liver cytosol and nuclei, both the ligands effectively radiolabeled several proteins analyzed by SDS-polyacrylamide gel electrophoresis/radioluminography. When [125I]AD12 was used at a concentration of 0.2 microM, two cytosolic proteins with molecular masses of 55 and 28 kDa and a nuclear protein of 40 kDa were specifically labeled, as coincubation with a 1000-fold excess of DHEAS inhibited labeling. Photoaffinity labeling of the cytosolic 28-kDa protein was also affected by Wy-14,643, but not by unsulfated dehydroepiandrosterone or androsterone sulfate, consistent with our previous findings obtained in competitive binding studies of [3H]DHEAS-binding detected in rat liver cytosol (Yamada et al. (1994) Biochim. Biophys. Acta 1224, 139-146). On the other hand, [125I]BZ5 specifically labeled a cytosolic protein of 31 kDa, which was inhibited by coincubation with bezafibrate, clofibric acid and Wy-14,643, but not with DHEAS. Thus, [125I]AD12 and [125I]BZ5 labeled several proteins which recognized DHEAS and bezafibrate, respectively, in rat liver cytosol and nuclei, providing a useful means to investigate PP-binding proteins.