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Biomedical subjects

F Kato

Publications and source records attributed to F Kato.

At least 19 recordsLinked to original sources
PubMed1995

Rhythm generation in the segmented hindbrain of chick embryos.

1. The embryonic hindbrain of chick is segmented until stage 24, when it starts to generate rhythmic activities in cranial nerves. In order to recognize a possible influence of segmentation on the organization of neuronal systems generating motor rhythms, the activity of trigeminal, facial, glossopharyngeal, vagal and hypoglossal nerves was studied during embryonic stages 24-36, by simultaneous recording of different cranial nerves in an isolated, superfused chick hindbrain preparation. 2. Highly correlated recurrent episodes of cyclical burst discharges occurred in all nerves studied (correlation coefficients, 0.8 +/- 0.1) throughout stages 24-36. 3. Such coactivation is unlikely to be due to monosynaptic connections between widely divergent premotor neurons and motoneurons, or between motoneurons themselves, because no short-term correlation was apparent in the millisecond range between activities of different motor nerves. 4. Complete transverse or midsagittal sectioning of the hindbrain disrupted coactivation of nerves located at distinct rostrocaudal levels or occupying an ipsi- or contralateral position, respectively, while sparing the ability of individual nerves to generate rhythmic activity. Each hindbrain segment thus contains bilaterally the motor nuclei together with their own rhythm generator. Coactivation of motor patterns appears to result from intersegmental and cross-median connections between these rhythm generators. 5. The results are in keeping with the hypothesis of a segmental organization of the primordial hindbrain rhythm generator and give further support to the early determination of both the anatomical and the functional fate of neurons in this region of the vertebrate central nervous system.

Animals↗
PubMed1995

Scoliosis and congenital heart disease.

STUDY DESIGN: This study analyzed clinical characteristics of scoliosis associated with congenital heart disease. Chest roentgenograms were reviewed to determine frequency, type, onset, and progression of scoliosis associated with congenital heart disease. OBJECTIVES: To determine which patients with scoliosis and congenital heart disease should be followed-up carefully. SUMMARY OF BACKGROUND DATA: Although several studies have been reported on scoliosis and congenital heart disease, the etiology of scoliosis in patients with congenital heart disease is still unknown. Furthermore, it has been difficult to determine the progression of scoliosis. METHODS: Chest roentgenograms of 680 patients who underwent cardiac operations because of congenital heart disease were evaluated. RESULTS: Seventy-four (10.9%) of these patients had scoliosis of more than 10 degrees, although most of them had mild curves. Scoliosis in patients under 10 years old undergoing cardiac operations was more severe than in those older than 10 years who underwent surgery. Scoliosis associated with congenital heart disease showed no particular features. Patients with patent ductus arteriosus showed left convex, high thoracic scoliosis after surgery. CONCLUSIONS: The mechanisms of onset of scoliosis in patients with congenital heart disease were not simple and were affected by several factors, including age at operation, side of approach, and type of congenital heart disease.

Adolescent↗
PubMed1995

Carotenoid synthesis in Streptomyces setonii ISP5395 is induced by the gene crtS, whose product is similar to a sigma factor.

In many species of actinomycetes, carotenogenesis can be photoinduced. The capacity to respond to photoinduction is, however unstable and, in various strains of Streptomyces, is lost at a relatively high frequency. In Streptomyces setonii ISP5395, which normally produces no carotenoids, carotenoid-producing mutants can be obtained following protoplast regeneration. We report here the characterization of a gene, crtS, which was isolated from one such mutant and can confer on wild-type S. setonii ISP5395 cells the capacity to synthesize carotenoids. Sequence analysis of crtS reveals an open reading frame, which shows homology to genes that encode alternative sigma factors in Bacillus subtilis. We propose that crtS encodes a sigma factor which is necessary for the expression of a cryptic gene(s) for carotenoid biosynthesis in S. setonii ISP5395.

Amino Acid Sequence↗
PubMed1995

Serial changes on MRI in lumbar disc herniations treated conservatively.

Using serial MRI, we studied 32 patients with herniated lumbar discs, treated conservatively, to clarify the natural history of this condition. MRI was performed in the acute stage, then 6 months and 1 year later. On axial images, the proportion of the cross-sectional area of the spinal canal occupied by the herniated disc was 31.9% on the average on the initial scan, 28.7% 6 months and 25.3% 1 year later. The size of the herniation decreased by more than 20% in 11 patients (34%), by 10-20% in 8 (28%) and was unchanged in 12 (38%). The height of the disc slightly decreased with time, but there was no significant change in the angle of lordosis in the affected segment. The initial MRI revealed degeneration of all affected discs, and progressive degeneration was observed in 9 patients. The more degenerate the disc and the larger the initial herniation the more the size of the herniated fragment decreased.

Adolescent↗
PubMed1995

Involvement of NMDA receptors in the respiratory phase transition is different in the adult guinea pig in vivo and in the isolated brain stem preparation.

1. We investigated the involvement of N-methyl-D-aspartate (NMDA) receptors in the respiratory pattern in an in vitro preparation of adult brain stem compared with in vivo conditions in the guinea pig. 2. In vivo, combining administration of the NMDA channel blocker dizocilpine (MK-801) (3 mg/kg) with a surgical section of the vagus nerves induced an apneustic type of respiration characterized by long inspiratory "holds," as has been shown in other species. The same effect was observed in hypothermic animals (30 degrees C). 3. The isolated in vitro brain stems from these apneustic animals did not present a prolonged inspiratory phase. A second dose of dizocilpine (100 microM perfused vascularly did not induce apneusis, even after increasing brain stem temperature to 35.5 degrees C. 4. In another group of isolated brain stems of adult guinea pigs anesthetized with pentobarbital sodium before decapitation, we perfused dizocilpine and NMDA through the basilar artery. The duration of periodic inspiratory motor activity recorded from the hypoglossal nerve was unaffected by dizocilpine (1-100 microM) or the competitive NMDA antagonist D- or DL-2-amino-5-phosphonopentanoic acid (100 microM and 1 mM), although respiratory frequency decreased. The increase in respiratory activity produced by vascularly perfused NMDA (25-100 microM) was blocked by dizocilpine (100 microM). 5. We conclude that the central mechanism of inspiratory termination in the vagotomized adult guinea pig requires the activation of NMDA receptors in vivo but not in vitro. This difference is not due to the hypothermic environment in vitro. Possible mechanisms for phase switching in vitro are discussed.

Animals↗
PubMed1995

Purification and properties of two chitinases from Streptomyces sp. J-13-3.

Two chitinases (Chi-A and Chi-B) purified from Streptomyces sp. J-13-3 had the same molecular weights (31,000) and enzymatic properties (optimum pH and temperature of pH 6.0 and 45 degrees C) but had significantly different isoelectric points (3.9 for Chi-A, 3.5 for Chi-B). Chi-A and -B had identical N-terminal amino acid sequences (ADXAAAWNASSVYTGGGSASYNGHN), similar amino acid compositions, and immunological cross-reactivities. A concomitant decrease of Chi-A and increase of Chi-B was observed in their productions during cultivation.

Amino Acid Sequence↗
PubMed1995

Molecular forms of human brain natriuretic peptide (BNP) in plasma of patients on hemodialysis (HD).

Plasma brain natriuretic peptide (BNP) levels have been reported to increase in patients with heart failure and end-stage renal disease (ESRD); however, little is known about molecular forms of plasma BNP that increase in these diseases. In the present study, we analyzed the molecular forms of plasma BNP in ESRD patients of both before (pre-) and after (post-) hemodialysis (HD) state. The plasma extract was analyzed by gel filtration on a TSK-GEL G2000 SW column followed by a RIA for both BNP and atrial natriuretic peptide (ANP). In the pre-HD patients, a 14- to 2300-fold increase in plasma level of immunoreactive (ir-) BNP was observed when compared to normal controls. A ratio of BNP-32 to g-BNP (pro BNP) in plasma from the patients was much larger than that in plasma from normal subjects, indicating that the high plasma level of ir-BNP level in the patients on HD largely results from a marked increase in BNP-32. HD significantly (P < 0.01) lowered the plasma levels of both BNP-32 and g-BNP with a greater reduction in BNP-32 than in g-BNP. Whereas, a-ANP was a main molecular form of plasma ANP in both pre- and post-HD plasma. These results suggest that plasma BNP-32 plays an important role in the sodium-fluid balance and that secretion and metabolism of BNP may differ from those of ANP in the HD patients.

Adult↗
PubMed1995

Effects of chondroitinase ABC on degenerative intervertebral discs.

The effects of chondroitinase ABC on surgically induced degenerative rabbit intervertebral discs were determined during a 12-week period by magnetic resonance imaging, radiography, and histologic examination. Rabbit intervertebral discs were surgically extruded, inducing disc degeneration 12 weeks before injection of chondroitinase ABC. Magnetic resonance imaging showed a hypointense area in the center of the surgically induced disc degeneration. After injection of chondroitinase ABC, the hypointense area became more intense, but reversed somewhat by the end of the 12-week period. Additional evidence of the effects of chondroitinase ABC on a surgically induced degenerative disc model was shown by radiographic evidence of shrinkage of the disc after injection. Histologic examination revealed a fibrous degenerative disc induced by surgical extrusion. However, the staining properties of the matrix of the nucleus pulposus was similar to that of normal discs before chondroitinase ABC injection, but diminished after the injection, with slight recovery at 12 weeks. The results suggest that chondroitinase ABC induces chemonucleolysis in the degenerated disc. Also, chondroitinase ABC does not destroy the degenerative disc matrix ability to regenerate after 12 weeks.

Animals↗
PubMed1994

Improved method for mutagenicity testing of gaseous compounds by using a gas sampling bag.

A simple and safety gas exposure method was developed using a gas sampling bag as an exposure vessel and a preparation vessel of diluted gas. The gas exposure conditions such as amount of S9 in the plate, volume of gas for the plate, amount of top agar, exposure period and exposure temperature were examined by mutagenicity testing of 1,3-butadiene using the gas sampling bag. Mutagenicity tests of 14 compounds and 1,3-butadiene on S. typhimurium TA98, TA100, TA1535 and TA1537, and E. coli WP2 uvrA were also examined by the developed gas exposure method. 1,3-Butadiene, propyne (methyl acetylene), monochlorodifluoromethane, ethylchloride, diborane and silane were mutagenic. 1-Butene, 2-butene, 2-methylpropene, methyl vinyl ether, trichlorofluoromethane, dichlorodifluoromethane, 1,2-dichloro-1,1,2,2-tetrafluoroethane, 1,1-difluoroethane and phosphine were not mutagenic on S. typhimurium TA98, TA100, TA1535 and TA1537, and E. coli WP2 uvrA with or without metabolic activation. These results were compatible with a previous report, and this developed method has the advantage that it can be tested easily and safely for combustible and self-combustible substances such as 1,3-butadiene and silane.

Animals↗
PubMed1994

Intraoperative ultrasonographic evaluation of the spinal cord in cervical myelopathy.

Intraoperative spinal ultrasonography (IOSS) was used to evaluate and monitor the spinal cord in 49 patients with cervical myelopathy. Intraoperative spinal ultrasonography demonstrated movements of the dura mater and the spinal cord at the cardiac rate, with some variability in intensity and mode. It also delineated the anterior surface of the spinal canal and configuration of the spinal cord. Statistical analysis showed no correlation between clinical outcome and morphologic restoration, and between clinical outcome and variations in intensity or mode of the pulsatile spinal cord movements. Spinal cord motions were surmised to be generated not only by the anterior spinal artery, but also by other factors. Dural pulsations clearly did not always imply the absence of compression of the spinal cord. Intraoperative spinal ultrasonography was thus quite useful for monitoring decompression in cervical myelopathy.

Adult↗
PubMed1994

Preschool sarcoidosis manifesting as juvenile rheumatoid arthritis: a case report and a review of the literature of Japanese cases.

Nine Japanese cases of sarcoidosis in children of 4 years of age or younger have been reported in the literature, including the case presented here. Clinically, preschool sarcoidosis is distinctly different from that of older children; it is characterized by a triad of skin, joint and eye lesions without pulmonary involvement. It is easily confused with juvenile rheumatoid arthritis which also presents the symptoms of arthritis and uveitis. We report on a patient with preschool sarcoidosis who was initially diagnosed as having juvenile rheumatoid arthritis. We recommend prompt skin biopsy to differentiate between these conditions.

Arthritis, Juvenile↗
PubMed1994

Anti-inflammatory and immunosuppressive effects of 1,6-anhydro-3,4-dideoxy-2-furfuryl-beta-D-threo-3-enopyranose (MT2221), a novel anhydro-enopyranose derivative, on experimental animal models.

The anti-inflammatory effects of 1,6-anhydro-3,4-dideoxy-2-furfuryl-beta-D-threo-3-enopyranose (MT2221) were investigated using animal models and compared with the effects of dexamethasone (DEX) and cyclosporin A (CYA). MT2221 inhibited carrageenan-induced acute inflammation and adjuvant arthritis in rats, as well as the delayed-type hypersensitive response and collagen-induced arthritis (CIA) in mice. However, it seemed that this compound was more effective against murine CIA than upon the other inflammation models. The MT2221 mode of action differed from those of conventional non-steroidal anti-inflammatory drugs (NSAIDs) and disease modifying anti-rheumatic drugs (DMARDs). All of these drugs are effective against acute inflammation or adjuvant arthritis models, but not against murine CIA. DEX and CYA did inhibit murine CIA, but in other animal models, their mode of action differed from that of MT2221. Moreover, allograft transplantation in mice showed that MT2221 slightly prolonged the allograft survival time. These results suggest that MT2221 has not only anti-inflammatory but also immunosuppressive effects based upon a novel mechanism of action that is different from NSAIDs, DMARDs, DEX and CYA.

Animals↗
PubMed1993

The increased signal intensity at the vertebral body endplates after chemonucleolysis demonstrated by magnetic resonance imaging.

Changes in signal intensity observed by magnetic resonance imaging in the contiguous end plates of injected discs after chemonucleolysis over a period of 2 years in 28 patients were evaluated. These changes appeared to be of two types; a transiently increased signal intensity on T2-weighted images, and a progressively increased signal intensity on T1-weighted images with isointense or hyperintense signal on T2-weighted images. The former appeared within three months and disappeared within 2 years. This change was observed in six patients (21%), whose mean age was higher than that of the other patients. This change correlated with the preinjection state of the affected disc. The latter appeared after 2 years and was accompanied by sclerotic changes on roentgenograms. These changes were observed in five patients (18%). The discs, of which the contiguous end plates showed these changes, did not recover the decreased nuclear signal intensity in four patients. These changes are considered to be a sign of degenerative spondylosis in the treated segment.

Adult↗
PubMed1993

[A case of intrathoracic dumb-bell ganglioneuroma and a surgical approach using spinal evoked potentials (SEP)].

A successfully treated case of a seven-year-old girl with a left intrathoracic Dumb-bell ganglioneuroma is reported. The tumor was 10 cm in diameter. Preoperative angiography revealed that the location of tumor was very close to the Adamkiewicz artery. In order to prevent the artery from damaging, spinal evoked potentials (SEP) was used during the surgery and was very useful for monitoring the spinal cord. Although SEP has often been employed in spine surgery, the literature on the use of it for posterior mediastinal tumor is scarce. It is considered that SEP is very useful for not damaging the feeding artery to the spinal cord, and for preventing the postoperative neurologic complications.

Child↗
PubMed1992

Changes seen on magnetic resonance imaging in the intervertebral disc space after chemonucleolysis: a hypothesis concerning regeneration of the disc after chemonucleolysis.

Measurements of the intervertebral disc space were made by magnetic resonance imaging and plain film examinations over a period of 2 years in 26 patients who had undergone chemonucleolysis. The height of the posterior portion of the disc decreased after 3 months and never recovered; the height of the anterior portion also decreased but recovered slightly over the same period. The angle of lordosis and the range of motion in the treated segment were decreased, but recovered. Marked decrease in signal from the disc was observed after 2 weeks which did not recover till 2 years after chemonucleolysis. We suspect that the disc degenerated markedly after chemonucleolysis and changed into a type of scar tissue, maturation of which could stabilize the affected segment.

Adolescent↗
PubMed1992

Intraoperative sonography of intramedullary spinal cord tumours.

Intraoperative spinal sonography was performed 23 times in 20 patients with intramedullary spinal cord tumours, and the sonographic features were examined. Eight cases of astrocytoma were classified into three types: type 1, seen in 3 children, had intramedullary, circular or oval, hyperechogenic multiple tumour shadows; type 2 presented inter-multimyelomere, relatively well-defined single tumour shadows corresponding to grade III and I for two juvenile and aged cases each, respectively; and type 3 appeared ill-defined and diffusely infiltrating. The relationships between these types, the ages of patients and histological grades were considered a potential clue to mechanisms of occurrence and infiltration of astrocytoma. All 7 ependymomas had syrinxes, of three types; central canal was very large, the tumour lying within it like an island; or the tumour was in contact with a cephalocaudal side part of the syrinx; or the tumour had a syrinx or cyst. Sonographic images thus differ according to the tumour, but differential diagnosis is currently limited. Development of sonographic equipment, with upgrading its resolving power are hoped for.

Adolescent↗
PubMed1992

Intraoperative ultrasonography of extramedullary spinal tumours.

Intraoperative spinal sonography (IOSS) was performed in 28 patients with extramedullary spinal tumours. Images were obtained of 31 tumours, because 2 patients had multiple tumours. There were 17 neurilemmomas, 9 meningiomas and 2 dermoid cysts. All tumours appeared well-defined and highly echogenic. There was no difficulty differentiating extramedullary spinal tumours from intramedullary masses excepting case, a big neurilemmoma at the conus medullaris. All images were assessed with reference to the surface of the lesions, the existence of cysts, and movement. Neurilemmomas had smooth surfaces, some cysts, and exhibited a "floating" movement. Meningiomas had irregular surfaces, were more highly echogenic than neurilemmomas, and adhered tightly to the dura mater. However, some neurilemmomas and meningiomas did not have these, and it was not always possible to differentiate them. Although IOSS has limitations of resolution, it gave useful information about the size of the tumours, the degree of displacement of the spinal cord, and even about the type of tumour in some cases. It was extremely helpful to the surgeon.

Adult↗