Yoshinori Miyasaka

Maclura pomifera agglutinin-binding glycoconjugates on converted apatite from synthetic octacalcium phosphate implanted into subperiosteal region of mouse calvaria

We have previously shown that the mineral in granules of synthetic octacalcium phosphate (OCP) implanted subperiosteally in mouse calvariae was converted to apatitic crystals and that the OCP implantation stimulated bone formation. The matrix components accumulated on the converted apatite were very similar to those of bone nodules (starting locus of calcification) in intramembranous osteogenesis. In the present study, the nature of the matrices accumulated on OCP implants in calvariae was compared with that of the matrices accumulated in abdominal subcutaneous implants. The comparison was facilitated by the use of Maclura pomifera agglutinin (MPA) lectin which is known to have a high affinity for the primary intramembranous bone matrix. Micro-beam x-ray diffraction indicated conversion of the implanted OCP to apatitic crystals in situ, both in subperiosteal and subcutaneous sites, after 10 days. Additional bone formation was detected on the converted apatite after 13 days in subperiosteal implantation, whereas bone was not formed in the subcutaneous implantation. MPA reaction was strongly manifested after 10 days in matrices accumulated on the converted apatite in both subperiosteal and subcutaneous implantations. Biochemical data showed that intensely and weakly MPA-blotted molecules (53.0 and 152.6 kDa, respectively) were in all the mouse sera, in the guanidine HCl-EDTA extracts of mouse calvarial bone and in the extracts of the implanted OCP in both subperiosteal and subcutaneous sites. These findings indicated that the glycoconjugates accumulated on the converted apatite from OCP were similar to the glycoconjugates in the serum in terms of reactivity with MPA and molecular weights. Furthermore, the results suggest that MPA-binding glycoconjugates which had accumulated on the converted apatite may be a requisite for the differentiation of mesenchymal cells into osteoblasts in periosteum but not in subcutaneous sites.

The mechanical behavior and morphological structure of callus in experimental callotasis.

Experimental callotasis was made in rabbit femurs. In order to compare mechanical behaviors and morphological structure of callus in callotasis, mechanical tests and histological examination were performed. Twenty Japanese white male rabbits were used. The right femurs were osteotomized at the level of the midshaft with a rotary cutter and fixed with a mini-model external fixator. After a 5-day waiting period, bone lengthening was started at the rate of 0.25 mm two times a day. Animals were divided into four groups. Group 1 and Group 2 were continual distraction group, Group 3 and Group 4 discontinued distraction group. The viscoelastic property was demonstrated in continual distraction group irrespective of distraction period, we thought the central undifferentiated connective tissue in callus was mainly responsible for the mechanical behavior. On the other hand, in discontinued distraction group, viscoelastic property shifted to elastic property corresponding to the rest period, we thought this change of mechanical behavior was histologically owing to the replacement of undifferentiated connective tissue by cartilage and the partial union of bone in callus.

Gait characteristics of sciatic nerve palsy--a report of four cases.

There are few reports concerning the gait characteristics of sciatic nerve palsy. Four cases, one with complete palsy and three with incomplete palsy, are presented. Complete palsy (case 1) was due to sacrifice of the sciatic nerve in a wide excision for chondrosarcoma in the left ischium. Incomplete palsy (cases 2, 3, and 4) was due to contusion incurred in traffic accidents. It is noteworthy that all four patients could walk with or without a short-leg brace. But the patients with complete loss of proprioception distal to the ankle (cases 1 and 2) had to watch their steps while walking to maintain their walking balance. This clinical analysis revealed that proprioceptive impairment of the sciatic nerve caused a walking disability even though the palsy was incomplete.

Bending and Torsion Fractures in Long Bones (A Mechanical and Radiologic Assessment of Clinical Cases)

Long bone injuries in clinical cases are studied by comparison of roentgenograms with a rational mechanical analysis of the injuries. Fractures produced by torsional loads have a spiral shape with a smooth and even surface. Fractures induced by bending loads have uneven and rugged fracture surfaces perpendicular to the bone axis. Long bones are weak in torsion but strong in tensile stress produced by bending. This result corresponds to the clinical fact that a large direct external force is needed to produce a transverse fracture while a spiral fracture is produced by a relatively small torque.

THEORY OF OSTEOGENESIS BEHAVIOR BASED ON CALCIUM DIFFUSION THEORY

Osteogenesis is completed by the nucleation mechanism on crystal nuclei formation and growth after amorphous calcium phosphate accretion to collagen fibers. For nuclei formation, it is necessary to have preliminary ionic diffusion such as that of Ca2+ and PO4(3-) ions to this part. Therefore, promotion of ionic diffusion to this part is the first essential condition for osteogenesis. We have considered this phenomenon as the nucleation mechanism accompanied by preliminary diffusion behavior and shown the optimum mechanical condition on promoting this ionic diffusion. Furthermore, we noticed callus by callotasis as the typical example which fits this mechanical condition and investigated its histology. However, necking occurs at the site of callus sandwiched by cortical bones due to tensile stress, three axial tensile stress in radial and tangential directions, in addition to the tensile stress occurs at the netsection of the callus due to the constraint of cortical bones. Therefore, the size of pore along the collagen lamination and hole zone becomes large under this mechanical condition and ionic diffusion such as Ca2+, PO4(3-) is liable to occur at this part. By solving the partial differential equation of the stress-induced diffusion, diffusive particles are shown to concentrate at the high three axial tensile stress region. Therefore, a high concentrated region of Ca, PO4 is achieved and selective osteogenesis due to hydroxyapatite nucleation is considered to progress in this region. Histological investigation of the callus of rabbit showed that mineralization occurs at this site and supports the theory of stress-induced diffusion on osteogenesis behavior.

Intraneural ganglion: review of the literature

Ganglions which occur in the nerves are named intraneural ganglion or nerve sheath ganglion. It should be considered in the differential diagnosis of any tumors causing neural disturbance. We review an intraneural ganglion, particularly arising in the common peroneal nerve with emphasis placed on usefulness of MRI for detecting this very unusual condition. MRI can clearly visualize a multilobular mass in the course of the nerve near the joint. The mass has low-signal intensities on T1-weighted images and homogenously high-signal intensities on T2-weighted images. The alteration of signal intensities of the muscles in the innervated compartments due to denervation is another finding for this unusual condition. During the surgery, dissection between ganglia and the nerve is difficult due to adhesions. Early diagnosis and treatment are recommended to prevent nerve damage.

Radial nerve palsy at the elbow.

We studied the clinical features and images along with surgical findings of 8 cages of radial nerve palsy due to a space-occupying lesion (SOL) at the elbow. Based on image findings, we examined compressing masses and their extent, we contrasted them with operative findings of the radial nerve, and we surmised the site of impairment. Compressing masses were ganglions in 6 cages, an old radial head dislocation in 1 case, and engorged radial recurrent vessels in 1 case. The extent of the SOLs was roughly 15–40 mm from the interepicondylar line and 0–30 mm from the radiohumeral joint. In operative findings, only the posterior interosseous nerve (PIN) was compressed in 5 cases, while both the PIN and superficial branch were compressed in 3 cases. No apparent correlation between operative findings and the type of palsy was found. The radial tunnel has yet to be defined clearly, but the radial nerve palsy is readily understandable in cases of SOLs via the definition of the radial tunnel as the tubular structure from the radiohumeral joint to the outlet of the supinator muscle.

Visco-Elastic Behavior of Callus in Rabbit Femurs

Experimental callotasis was induced in rabbit femurs and mechanical tests were performed for the callus in callotasis in order to investigate its mechanical behaviors when tensile loads were applied.

Field distribution of compound muscle action potentials of the calf muscles in rabbits.

The purpose of this study is to verify that compound muscle action potentials (CMAPs) generated a stationary potential and to examine extension of the CMAPs away from the stimulated muscle. A referential derivation and/or bipolar derivation to record the stationary potentials were carried out following tibial nerve stimulation at the popliteal fossa in 10 rabbits. After recording a bipolar and/or referential derivation, wave changes were monitored before and after severing the tibial nerve. The change of the wave by compressing or direct electrical stimulation to the calf muscle was also monitored. In referential derivatives, the stationary waves were observed on top of the skull in all the rabbits examined with the peak latency of the potentials from 3.78 msec to 5.04 msec. In bipolar derivations, the upper limits of the stationary waves recorded were the trunks. The peak latencies were from 2.35 msec to 5.46 msec with an average of 4.12 msec. By analyzing the results from severing the tibial nerves, compressing the calf muscles, and direct electrical stimulation of the calf muscle, the origin of these stationary potentials was determined to be CMAPs of the calf muscles. These findings suggest contamination of the stationary potentials originated by CMAPs for recording of any evoked potentials when motor nerves are stimulated.