Search PubMed⌕ Search

Biomedical subjects

Y Toyama

Publications and source records attributed to Y Toyama.

At least 37 records · Page 2Linked to original sources
PubMed2004

Ischaemic contracture in an infant's forearm--a case report.

We present a case of a gradually developing ischaemic contracture of the forearm muscles of an infant who developed without any trauma or acute gangrene at birth. Release of the middle and ring finger digitorum profundus muscles and pronator quadratus at 2 years of age corrected the deformity. Histopathology showed no evidence of fibromatosis or any other tumor. Although a dynamic splint was used to maintain the range of motion, the range of the middle finger motion deteriorated gradually 2 years after surgery. Though the pathogenesis of this problem was unclear, we assume that it was caused by fibrosis of muscles as a result of bleeding before or during delivery.

Compartment Syndromes↗
PubMed2003

Use of multislice helical computed tomography cholangiography in the diagnosis of biliary disease.

A recent advance in computed tomography (CT) technology, multislice helical CT, has enabled production of clearer three-dimensional (3D) images and has drawn interest. We report the usefulness of CT cholangiography using a multislice helical CT scanner for the diagnosis and preoperative imaging of the biliary duct in a case of peculiarly shaped gallbladder with cholecystitis. A 34-year-old woman admitted to our hospital presented with chronic hypochondralgia. A CT scan showed that the gallbladder was normal without wall thickening or stones. However, there appeared to be a tumor, containing a stone approximately 1 cm in diameter, attached under the gallbladder in front of the right kidney and extending up to its lower level. Magnetic resonance cholangiography also depicted a normal gallbladder without wall thickening or stones. Hence, gallbladder stones were not diagnosed by previously the mentioned investigations. In contrast, a 3D image produced by multislice helical CT cholangiography was very clear. From the bottom of the gallbladder, a narrow canal continued to a stone. We diagnosed that the wall of the lower part of the long gallbladder had become thick and elongated because of chronic cholecystitis caused by a gallbladder stone, and laparoscopic cholecystectomy was performed. Macroscopically, the resected gallbladder showed an extremely thickened wall from the lower body to the fundus, in which a stone was located in the center. Multislice helical CT cholangiography has the potential to become one of the most significant examinations for diagnosis and anatomical analysis of biliary disease prior to laparoscopic cholecystectomy.

Adult↗
PubMed2003

The shape of the triangular fibrocartilage during pronation-supination.

We studied the changes in the shape of the triangular fibrocartilage (TFC: disc proper) which occur during forearm rotation in disarticulated and articulated wrists. The influence of artificial 3mm ulnar lengthening on distortion of the disc was also examined. In the disarticulated wrists, slight distortion of the central and radial portions of the TFC was observed in the ulnar neutral variance specimens. More distortion was noted in the radial and central portions of the TFC in specimens with positive ulnar variance or with the ulna lengthened. However, in the articulated wrist, the TFC demonstrated little change in shape during pronosupination even in the ulnar positive variance wrists or with the ulna lengthened. There was no significant change in palmar and dorsal peripheral lengths of the TFC in ulnar neutral, ulnar positive or ulna-lengthened specimens at three rotatory positions of the forearm. These findings suggest that changes in ulnar variance which occur during forearm rotation can produce distortion on the TFC, but the carpus helps to maintain the shape of the TFC during pronation-supination, even with positive ulnar variance.

Aged↗
PubMed2003

Changes of cervical spinal cord and cervical spinal canal with age in asymptomatic subjects.

STUDY DESIGN: Prospective study on magnetic resonance imaging (MRI) and radiographic findings of the cervical spine. OBJECTIVE: To elucidate the age-related changes of the cervical spinal cord and the cervical spinal canal and the relationship between the spinal cord and the spinal canal in asymptomatic subjects using MRI and radiography. SETTING: Tokyo, Japan. METHODS: The transverse area of the cervical spinal cord and the ratio of the anteroposterior diameter to the transverse diameter (RAPT) were investigated, using MRI in 229 asymptomatic subjects. The sagittal spinal canal diameter and anteroposterior diameter of the cervical vertebral body were also measured on plain lateral radiographs. The canal body ratio (CBR), which was defined as the diameter of the spinal canal divided by that of the vertebral body, was calculated. RESULTS: The transverse spinal cord area correlated negatively with age. RAPT did not correlate with age. The CBR correlated negatively with age. The correlation between spinal cord area and CBR was significant but weak and the correlation between RAPT and CBR was not significant. CONCLUSION: The transverse area of the cervical spinal cord measured by MRI decreased with age, while RAPT remained unchanged. The bony spinal canal became narrower with age. The spinal cord area and the shapes of the spinal cord were independent from the spinal canal diameter in asymptomatic subjects. These facts should be considered when evaluating radiological findings in patients with cervical spinal disorders.

Adolescent↗
PubMed2003

Clinical features associated with recurrence of tumours of the spinal cord and cauda equina.

STUDY DESIGN: Retrospective review of consecutive cases of recurrent spinal cord and cauda equina tumours. OBJECTIVES: We sought to identify factors and conditions resulting in re-operation to treat recurrences of spinal cord and cauda equina tumours. SETTING: Keio University Hospital, Tokyo, Japan. METHODS: Re-operation was performed in 39 patients with spinal cord and cauda equina tumours. Times of operation, interval between operations, affected spinal level, tumour site on cross section, configurations among dumb-bell tumours, and pathologic diagnoses were analysed. Recurrence rates were defined in terms of the number of cases with re-operation due to tumour recurrence relative to the total number of surgical cases for the same period at our institution. RESULTS: Recurrence rates were relatively high for intradural, extramedullary tumours and for tumours located anteriorly rather than laterally. Of patients with intradural, extramedullary plus extradural tumours who underwent initial surgery at our hospital, 75% (9/12) recurred; all tumours had dumb-bell-type configurations. The overall rate of re-operation due to tumour recurrence in 249 cases was 7.2% at our institution. By tumour types, 40% of malignant schwannomas recurred (2/5), as did 35.7% of neurofibromas (5/14), and 33.3% of ependymomas (6/18). CONCLUSION: Risk factors for tumour recurrence were anterior location, an intradural, extramedullary plus extradural site, extensive dumb-bell tumours, and pathologic diagnoses of neurofibroma, ependymoma, or malignant schwannoma.

Adolescent↗
PubMed2002

Transplantation of in vitro-expanded fetal neural progenitor cells results in neurogenesis and functional recovery after spinal cord contusion injury in adult rats.

Neural progenitor cells, including neural stem cells, are a potential expandable source of graft material for transplantation aimed at repairing the damaged CNS. Here we present the first evidence that in vitro-expanded fetus-derived neurosphere cells were able to generate neurons in vivo and improve motor function upon transplantation into an adult rat spinal-cord-contusion injury model. As the source of graft material, we used a neural stem cell-enriched population that was derived from rat embryonic spinal cord (E14.5) and expanded in vitro by neurosphere formation. Nine days after contusion injury, these neurosphere cells were transplanted into adult rat spinal cord at the injury site. Histological analysis 5 weeks after the transplantation showed that mitotic neurogenesis occurred from the transplanted donor progenitor cells within the adult rat spinal cord, a nonneurogenic region; that these donor-derived neurons extended their processes into the host tissues; and that the neurites formed synaptic structures. Furthermore, analysis of motor behavior using a skilled reaching task indicated that the treated rats showed functional recovery. These results indicate that in vitro-expanded neurosphere cells derived from the fetal spinal cord are a potential source for transplantable material for treatment of spinal cord injury.

Age Factors↗
PubMed2002

Effect of etidronate on bone in orchidectomized and sciatic neurectomized adult rats.

The purpose of the present study was to determine whether etidronate treatment could prevent bone loss caused by orchidectomy (ORX) and unilateral sciatic neurectomy (NX) in adult male rats. Seventy-four male Wistar rats, aged 10 months, were randomly divided into eight groups: baseline controls (n = 10); age-matched sham-operated controls (AMC; n = 9); ORX (n = 9); NX (n = 10); ORX + NX (n = 9); ORX + etidronate treatment (ORX + E; n = 7); NX + E (n = 10); and ORX + NX + E (n = 10). Etidronate treatment (10 mg/kg per day subcutaneously) was initiated 2 weeks after surgery and was continued for 2 weeks. Four weeks after surgery, bone mineral density (BMD) of the proximal and middle tibia (PT and MT, respectively), distal and middle femur (DF and MF, respectively), and fourth lumbar vertebral body (LVB) was measured by dual-energy X-ray absorptiometry (Model DCS-600, Aloka, Tokyo, Japan). The mechanical properties of the MF and third LVB were measured by three-point bending and compression tests, respectively. Levels of urinary deoxypyridinoline (Dpd) and serum osteocalcin (Oc) were also measured by enzyme-linked immunosorbent assay. Four weeks of aging had no significant effects on BMD, bone mechanical properties, or bone markers. ORX significantly increased the levels of urinary Dpd and serum Oc, which resulted in significant decreases in BMD of the PT, MT, DF, MF, and fourth LVB, as well as the mechanical strength (maximum load) of the MF and third LVB. NX significantly increased levels of urinary Dpd and decreased levels of serum Oc, resulting in a significant decrease in BMD of the PT, DF, and fourth LVB. The ORX-induced decrease in BMD of the PT was more pronounced when combined with NX. Etidronate treatment for NX, ORX, and ORX + NX rats significantly decreased levels of urinary Dpd and serum Oc, resulting in complete prevention of loss of BMD and/or bone mechanical strength. The present study demonstrates the efficacy of etidronate treatment for prevention of bone loss caused by testosterone deficiency and immobilization in adult male rats.

Age Factors↗
PubMed2002

Development of the blood-testis barrier in the mouse is delayed by neonatally administered diethylstilbestrol but not by beta-estradiol 3-benzoate.

A group of newborn mice were treated with 1 micro g dose-1 individual-1 of diethylstilbestrol (DES) on alternate days, from days 1 to 11 postnatally. Another group of mice were treated similarly with 125 ng dose-1 individual-1 of beta-estradiol 3-benzoate (E2B). The testes were sequentially examined up to 84 days of age using light and electron microscopy. Spermatogenic cells in the DES-treated mice differentiated normally from birth until 17 days of age, when they differentiated into pachytene spermatocytes and remained at this meiotic prophase for the next 10 days approximately. The cells then began to differentiate further, ultimately forming spermatozoa by 49 days of age. Confocal and electron microscopy showed that the blood-testis barrier did not form until 28 days of age in the DES-treated mice, and a delay in the functional maturation of this structure, as the blood-testis barrier, was confirmed by intercellular tracer experiments. The arrest of spermatogenesis at the meiotic prophase may have been attributable to the DES-induced defective formation of the blood-testis barrier. No delay of the blood-testis barrier formation was detected in the E2B-treated mice. Thus, DES and E2B, both of which are known as potent oestrogenic compounds, had different effects on the Sertoli cells.

Animals↗
PubMed2002

Comparison of 201 Tl- with 67 Ga single photon emission tomography in the diagnosis of head and neck cancer recurrence.

The purpose of this study was to evaluate the usefulness of 201Tl single photon emission tomography (SPET) in comparison with 67Ga SPET for distinguishing recurrent tumours in patients previously treated for head and neck cancer. A total of 37 patients with suspicion of recurrent cancer were investigated. SPET images with 201Tl were acquired 10min (early) and 3h (delayed) and SPET images with 67Ga were acquired 72h, after injection. The visual and semiquantitative (T/N ratio) analysis were performed. On visual analysis, results from early 201Tl SPET were the same as those from delayed 201Tl SPET. The sensitivity, specificity and accuracy of the diagnosis of local recurrence using 201Tl SPET were all 100%. The three values using 201Tl SPET for neck lymph node metastases were 73%, 100% and 91%. The corresponding values using 67Ga SPET for local recurrence were 57%, 100% and 89%, respectively, and those using 67Ga SPET for neck lymph node metastases 55%, 100% and 84%, respectively. In the semiquantitative analysis, there was a statistically higher T/N ratio obtained using 201Tl when compared with 67Ga. 201Tl early SPET, especially, has the potential to replace 67Ga SPET in the follow-up of patients with head and neck cancer.

Adult↗
PubMed2002

99mTc-MIBI and 201Tl SPET in the detection of recurrent brain tumours after radiation therapy.

The purpose of this study was to evaluate whether Tc-hexakis-2-methoxyisobutylisonitrile ( Tc-MIBI) or Tl single photon emission tomography (SPET) could detect recurrent tumours in patients with previous radiation therapy for brain tumours. Dual SPET with Tc-MIBI and Tl was performed in 21 patients suspected of having recurrent brain tumours. SPET images were acquired 15 min (early) and 2 h (delayed) after injection. The ratio of the average counts for the region of interest in the lesion area and its mirror image in normal brain tissue was obtained. Early and delayed ratios were calculated. On the basis of histological and/or clinical findings, the final diagnosis was considered as recurrent tumours in 15 patients and radiation necrosis in six. Both ratios using Tc-MIBI and Tl were significantly higher in recurrent tumours than in radiation necrosis. Based on a cut-off of 5.89 of the early ratio using Tc-MIBI to distinguish between recurrent tumours and radiation necrosis, the accuracy was 90%. Based on a cut-off of 6.77 of the delayed ratio using Tc-MIBI, the accuracy was 86%. The corresponding values using cut-offs of 2.40 and 1.85 with Tl were 90% and 86%, respectively. However, within recurrent tumours, both ratios for Tc-MIBI were significantly higher than those for Tl. Early Tc-MIBI SPET may be especially useful for the detection of recurrent tumours in patients who have previously undergone radiation therapy for brain tumours.

Adult↗
PubMed2001

Intraspinal cyst communicating with the intervertebral disc in the lumbar spine: discal cyst.

STUDY DESIGN: A retrospective case study of patients with intraspinal cyst having a distinct connection with the corresponding intervertebral disc. OBJECTIVES: To propose a new clinical entity, "discal cyst," by clarifying the clinical, radiographic, and histologic aspects of the disease. SUMMARY OF BACKGROUND DATA: Several types of intraspinal cysts with different pathogenesis, causing symptoms indistinguishable from those of lumbar disc herniation, have been reported, such as perineural cysts, synovial cysts, and ganglion cysts. However, to the authors' knowledge, no detailed analysis has been made of cysts that have a distinct connection with the corresponding intervertebral disc. METHODS: Clinical pictures, radiographic findings, and surgical and histologic findings in eight surgically treated patients with intraspinal cyst having a distinct connection with the intervertebral disc were reviewed. Possible pathogenesis and a proposal for nomenclature were also discussed. RESULTS: This disease can be characterized by (1) clinical symptoms indistinguishable from those of typical disc herniation, manifesting as a unilateral single nerve root lesion; (2) incidence at slightly younger age and at upper intervertebral levels than with typical disc herniation; (3) T1 low signal and T2 high signal intensity, round to oval mass lesion on magnetic resonance imaging, compatible with a liquid-containing cyst; (4) minimal degeneration of the involved disc, either on discography/computed tomographic discography or magnetic resonance imaging; (5) a connection between the cyst and the corresponding intervertebral discs on discograms with severe radiating pain in the affected leg at the time of injection; (6) immediate relief of symptoms after simple removal of the cyst; (7) cyst wall consisting of dense fibrous connective tissue containing bloody to clear serous discharge; and (8) absence of disc materials and a specific lining cell layer on histologic examination. Although the exact cause is unknown, underlying minor disc injury may serve as a basis for cyst formation. CONCLUSION: Eight cases of intraspinal cysts communicating with the intervertebral disc presenting symptoms identical to those of disc herniation are presented. Because all cysts were connected to the corresponding disc and the development of the cyst was assumed to be related to underlying disc injury, it is proposed to name this clinical entity discal cyst.

Adult↗
PubMed2001

Increase of oligodendrocyte progenitor cells after spinal cord injury.

The reaction of oligodendrocyte progenitor cells (OPCs) after spinal cord injury (SCI) is poorly understood. In this study, we examined oligodendroglial reactions after contusion SCI in adult rats by immunohistochemistry. OPCs were identified by staining with monoclonal antibodies (mAbs) A2B5 and O4. Each of the A2B5-, O4-positive OPCs and galactocerebroside-positive oligodendrocytes dramatically increased in the lesion of the dorsal posterior funiculus. Bromodeoxyuridine (BrdU) incorporation studies showed that most O4-positive cells in the lesion were labeled with BrdU, suggesting that these OPCs were proliferative. In contrast, the expression of myelin basic protein was decreased in the lesion compared with controls that received laminectomy only. From the injured cord, OPCs were isolated by immunopanning with mAb A2B5. We observed an increased number of OPCs from the injured spinal cords compared with those isolated from controls and unoperated animals. After several days in culture, the OPCs from the lesion expressed galactocerebroside. These results suggest that OPCs are induced and can differentiate following SCI in the adult rat.

Animals↗
PubMed2001

Fast heating of ultrahigh-density plasma as a step towards laser fusion ignition.

Modern high-power lasers can generate extreme states of matter that are relevant to astrophysics, equation-of-state studies and fusion energy research. Laser-driven implosions of spherical polymer shells have, for example, achieved an increase in density of 1,000 times relative to the solid state. These densities are large enough to enable controlled fusion, but to achieve energy gain a small volume of compressed fuel (known as the 'spark') must be heated to temperatures of about 108 K (corresponding to thermal energies in excess of 10 keV). In the conventional approach to controlled fusion, the spark is both produced and heated by accurately timed shock waves, but this process requires both precise implosion symmetry and a very large drive energy. In principle, these requirements can be significantly relaxed by performing the compression and fast heating separately; however, this 'fast ignitor' approach also suffers drawbacks, such as propagation losses and deflection of the ultra-intense laser pulse by the plasma surrounding the compressed fuel. Here we employ a new compression geometry that eliminates these problems; we combine production of compressed matter in a laser-driven implosion with picosecond-fast heating by a laser pulse timed to coincide with the peak compression. Our approach therefore permits efficient compression and heating to be carried out simultaneously, providing a route to efficient fusion energy production.

Journal Article↗
PubMed2001

Relationships between outcomes of conservative treatment and magnetic resonance imaging findings in patients with mild cervical myelopathy caused by soft disc herniations.

STUDY DESIGN: A retrospective follow-up study of conservatively treated patients with mild cervical myelopathy caused by cervical soft disc herniation. OBJECTIVE: To investigate the outcome of conservative treatment for patients with mild myelopathy caused by cervical soft disc herniation and to evaluate usefulness of magnetic resonance findings in the prediction of the outcomes. SUMMARY OF BACKGROUND DATA: Recent studies on conservative treatment for cervical soft disc herniation have focused mainly on radiculopathy, and not on myelopathy. METHODS: Twenty-seven patients with mild cervical myelopathy secondary to cervical soft disc herniation were treated conservatively for more than 6 months by cervical bracing and restriction of daily activities. Of the 27 patients, 17 patients (Group A) underwent conservative treatment only and it was associated with improvement in their neurologic deficits, while the other 10 patients (Group B) ultimately underwent decompression surgery because of neurologic deterioration. Comparisons between the two groups were made in regard to JOA scores, patient satisfaction, and magnetic resonance findings, including location of the disc herniation (focal or diffuse in the sagittal plane, median or paramedian in the axial plane). RESULTS: The JOA scores were 13.6 +/- 1.6 in Group A and 14.1 +/- 1.6 in Group B before treatment, 14.9 +/- 1.0 and 12.9 +/- 2.1, respectively, at 3 months, and 16.2 +/- 0.8 and 16.0 +/- 1.2, respectively, at the final follow-up. The JOA scores at 3 months were significantly lower in Group B than in Group A. Satisfaction with the results of treatment at the final follow-up was reported by 77% of the patients in Group A and 90% in Group B. Focal-type herniation was present in 47% of the patients in Group A and 70% in Group B, while median-type herniation was diagnosed in 77% in Group A and 30% in Group B. Follow-up magnetic resonance imaging of the patients in Group A showed spontaneous regression of a herniated mass in 10 patients (59%). Diffuse-type herniations were more likely to regress spontaneously than focal-type herniations (78% vs. 37%). CONCLUSIONS: Conservative treatment is an effective treatment option for mild cervical myelopathy caused by cervical soft disc herniation. A good outcome can be expected in patients with a median-type and/or diffuse-type herniation on magnetic resonance imaging.

Adult↗
PubMed2001

beta-estradiol 3-benzoate affects spermatogenesis in the adult mouse.

beta-estradiol 3-benzoate (E(2)B) (10, 16, 20, 40, 80 and 160 microg/kg body weight) was administered daily to experimental groups of adult mice for the following periods; 2, 3 days, 1, 2, 4, and 8 weeks. Morphological changes in the testes were observed by both light and electron microscopy. Exfoliation of the germ cells was observed in the lumen of the seminiferous tubule. The spermatogenic cycle, especially stage XII, was disordered. Spermatids older than step 6 were severely affected. Detected abnormalities in the spermatids were deformation of the nucleus and acrosome. Partial deletion in the Sertoli-spermatid ectoplasmic specialization was also observed. Germ cells younger than step 7 spermatids were not affected morphologically. These abnormalities were not detected in the mice treated with the chemical at less than 16 microg/kg body weight. It is concluded that the chemical seems to affect round spermatids metabolically, but the morphological effect can be detected only from the spermatids older than step 6. The effects of the chemical on adult mice were reversible.

Animals↗
PubMed2001

Generation of dopaminergic neurons in the adult brain from mesencephalic precursor cells labeled with a nestin-GFP transgene.

Mesencephalic precursor cells may one day provide dopaminergic neurons for the treatment of Parkinson's disease. However, the generation of dopaminergic neurons from mesencephalic precursors has been difficult to follow, partly because an appropriate means for recognizing mesencephalic ventricular zone precursors has not been available. To visualize and isolate mesencephalic precursor cells from a mixed population, we used transgenic mice and rats carrying green fluorescent protein (GFP) cDNA under the control of the nestin enhancer. nestin-driven GFP was detected in the mesencephalic ventricular zone, and it colocalized with specific markers for neural precursor cells. In addition, data from flow-cytometry indicated that Prominin/CD133, a cell-surface marker for ventricular zone cells, was expressed specifically in these GFP-positive (GFP(+)) cells. After sorting by fluorescence-activated cell sorting, the GFP(+) cells proliferated in vitro and expressed precursor cell markers but not neuronal markers. Using clonogenic sphere formation assays, we showed that this sorted population was enriched in multipotent precursor cells that could differentiate into both neurons and glia. Importantly, many neurons generated from nestin-GFP-sorted mesencephalic precursors developed a dopaminergic phenotype in vitro. Finally, nestin-GFP(+) cells were transplanted into the striatum of a rat model of Parkinson's disease. Bromodeoxyuridine-tyrosine hydroxylase double-labeling revealed that the transplanted cells generated new dopaminergic neurons within the host striatum. The implanted cells were able to restore dopaminergic function in the host striatum, as assessed by a behavioral measure: recovery from amphetamine-induced rotation. Together, these findings indicate that precursor cells harvested from the embryonic ventral mesencephalon can generate dopaminergic neurons able to restore function to the chemically denervated adult striatum.

AC133 Antigen↗