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Biomedical subjects

M Yamagata

Publications and source records attributed to M Yamagata.

At least 109 records · Page 6Linked to original sources
PubMed1995

[Vimentin and desmin expression in the type 2 fibers in muscle biopsies from myotonic dystrophy patients].

Immunoreactivity for the intermediate filament proteins vimentin and desmin was assessed in the type 2 fibers of biceps brachii muscle biopsies from 20 adults with myotonic dystrophy (MD). Some type 2C fibers showed strong reactivity with both anti-vimentin and anti-desmin, suggesting that they were regenerating fibers. Some type 2A and 2B fibers of various diameter were weakly reactive with anti-vimentin, but none of the type 1 fibers were reactive with anti-vimentin. Hardly any reactivity with anti-vimentin was demonstrated in patients in the younger age group (10-29 years) with mild illness, but vimentin-positive type 2 fibers increased in the age groups 30 years of age and older. The mean diameters of type 2A and type 2B fibers in vimentin-positive patients were larger than in vimentin-negative patients. In the patients in the 30 years of age and older group, the vimentin-negative patients had more severe muscle weakness than the vimentin-positive patients. These findings suggest a possible relationship between the process of regeneration in type 2 fibers in adult MD patients and the increase in their mean diameter.

Adolescent↗
PubMed1995

Recurrence near the resection line of hepatocellular carcinoma in the anterosuperior subsegment of the liver--the effect of the argon beam coagulator.

The present paper examines the relationship between the patterns of intrahepatic recurrence after resections of hepatocellular carcinoma and surgical margins in cases located in the anterosuperior subsegment of the liver. In 95 curative resections of the liver for hepatocellular carcinomas less than 5 cm in size, 29 tumors were located in the anterosuperior subsegment of the liver. The recurrence rates of tumors in the anterosuperior subsegment and other regions were 16/29 (55.2%) and 39/66 (59.1%), respectively. Recurrences near the resection line were significantly more common in the anterosuperior subsegment (6/29) than in other regions (2/66) of the liver (P < 0.05). The surgical margin from the tumor edge to the resection line was significantly shorter in tumors of the anterosuperior subsegment (4.6 +/- 9.7 mm) than in those of other regions (9.7 +/- 10.6 mm) (P < 0.01). The effect of an argon beam tissue coagulator was also examined in rat livers. Exposure to an argon beam tissue coagulator for 10, 30 and 60 seconds at a power setting of 100 watts was capable of burning out tissue to a depth of 6.0, 10.5 and 13.3 mm from the resection line of the rat liver, respectively. An exposure of 10 seconds is thought to be sufficient to destroy any microscopic residues of malignant cells near the resection line. Thus, an argon tissue coagulator could potentially be of value for the prophylaxis of recurrence near the resected surface.

Animals↗
PubMed1995

Lamina-specific expression of adhesion molecules in developing chick optic tectum.

The optic tectum is the major synaptic target of retinal axons in birds. In the chick, retinal ganglion cell axons enter the optic tectum through a superficial lamina (the stratum opticum), extended branches into deeper laminae, and arborize in specific "retinorecipient" laminae, where they form synapses. Studies using an organotypic culture system have provided evidence that the tectum bears a series of distinct, lamina-specific, cell surface-associated cues that direct these axonal behaviors (Yamagata and Sanes, 1995). Here, we have used a panel of antibodies to 30 membrane and matrix components to ask whether known adhesive molecules are distributed in lamina-specific patterns. Among many spatiotemporal pattern of expression documented, three were particularly noteworthy: (1) The cell adhesion molecules NgCAM/L1 and TAG-1/axonin-1 were concentrated in the stratum opticum. (2) SC1/JC7/DM-GRASP/BEN, N-cadherin, neuropilin, polysialylated N-CAM, and glycoconjugates recognized by the lectin VVA-B4 were concentrated in retinorecipient laminae. (3) Neurofascin, tenascin-C/cytotactin, and a matrix molecule defined by the "Sigma" antibody were present at highest levels in areas that border the retinorecipient laminae. Some members of each group (NgCAM/L1, TAG-1/axonin, SC1/JC7, polysialic acid, VVA-B4-receptors, and neurofascin) appeared on schedule and in lamina-restricted patterns in tecta from embryos that had been enucleated before retinal axons left the eye. Thus, molecules in these three categories could provide signals to retinal axons that promote extension through the stratum opticum, induce arborization or synaptogenesis in retinorecipient laminae, and prevent sprouting into adjoining laminae. Interestingly, N-cadherin accumulated in retinorecipient laminae only following the onset of synapse formation, and failed to accumulate in enucleated tecta. Immunoelectron microscopy of normal tecta demonstrated the presence of N-cadherin in the synaptic cleft, suggesting a role for this molecule in synaptic maintenance.

Animals↗
PubMed1994

Interspecific comparisons reveal conserved features of the Drosophila Toll protein.

The Toll gene of Drosophila melanogaster produces a transmembrane cell adhesion protein that is required to establish the dorso-ventral axis of the embryo. The Toll protein's extracellular domain contains Leu-rich repeats (LRR), implicated in intermolecular interactions, and its large intracellular domain transduces a signal that eventually reaches the nucleus. Here, we report amino-acid (aa) sequences encoded by the Toll genes of D. pseudoobscura and D. virilis, and two distinct Toll-like genes of the grasshopper, Schistocerca americana. Interspecific comparisons show a Toll-specific subfamily of LRR, and a strikingly high degree of conservation in the cytoplasmic domain. Interestingly, many aa residues conserved among the insect Toll-like cytoplasmic domains are also conserved in mammalian and avian type-I interleukin-1 receptors and the hypothetical product of a transcript, MyD88, found in murine myeloid cells. Thus, we identify a set of conserved aa in the cytoplasmic domain which might be used in a signal-transduction pathway shared by invertebrates and vertebrates.

Amino Acid Sequence↗
PubMed1994

Three-dimensional motion of the upper cervical spine in rheumatoid arthritis.

Rheumatoid arthritis frequently contributes to instability of the upper cervical spine. Rotational instability of the upper cervical spine was evaluated in rheumatoid arthritis patients using biplanar x-ray photogrammetry. Three-dimensional cervical motion and the instantaneous axis of rotation of the atlas relative to the axis were evaluated in normal and rheumatoid arthritis patients during axial rotation in the horizontal plane. Anterior atlantoaxial subluxation did not increase during axial head rotation in either the atlantoaxial subluxation or the vertical subluxation groups, while the instantaneous axes of rotation were distributed posteriorly in the dens in the RA-normal group, but were widely scattered in the atlantoaxial subluxation group.

Arthritis, Rheumatoid↗
PubMed1994

Muscle histopathology in myotonic dystrophy in relation to age and muscular weakness.

We studied histopathological changes in the biceps brachii muscle in relation to age and the degree of muscle weakness in 64 patients (aged 11-59 years) with myotonic dystrophy. The proportion of type 1 fibers was unaltered in the adolescent patients compared with control values, but increased with age. The average diameters of all the fiber types were smaller than control values in the adolescents, suggesting immature development; however, there was an increase in diameter with age that was associated with an increase of hypertrophic type 2 fibers. At all ages, type 1 fibers were smaller than type 2 ones. Small angular fibers and small group atrophy consisted mainly of type 1 fibers, their incidences decreasing with age. The severity of muscular weakness was related to the predominance of type 1 fibers, the reduction in the number of hypertrophic type 2 fibers, and the accumulation of adipose cells, but not to the presence of small angular fibers or to small group atrophy.

Adult↗
PubMed1994

Gene transfer to avian embryos with a recombinant adenovirus.

Replication-defective adenoviral vectors are widely used for gene transfer into mammalian cells. We show here that these vectors are also useful for delivering genes to chick embryos. Cells of many tissues expressed Escherichia coli beta-galactosidase following infection in vitro or in ovo with a recombinant adenoviral vector carrying this reporter gene. Labeled cells were morphologically normal and integrated normally into host tissues. Moreover, cells labeled in neural crest and somites subsequently migrated along normal paths. However, restricted subsets of cells were infected in some tissues at some stages, suggesting complex control of adenoviral infectivity and/or expression.

Adenoviruses, Human↗
PubMed1994

Relationship between bone mineral density of the proximal femur and lumbar spine and quadriceps and hamstrings torque in healthy Japanese subjects.

The purpose of this study was to examine the correlations between the muscle torque of the leg extensors (quadriceps femoris) and leg flexors (hamstrings) and the bone mineral density (BMD) of the proximal femur and lumbar spine. To investigate the decline in BMD of proximal femur and lumbar spine, we examined the relative importance of muscle torque, age, and body weight in the prediction of BMD in 340 healthy volunteers (109 males, and 231 females). Age and body weight were independent predictors of femoral BMD in men. Body weight and quadriceps torque were independent predictors of femoral BMD in premenopausal women. Body weight and years after menopause were independent predictors of BMD in postmenopausal women. The BMD was greatly affected by menopause, whereas the muscle torque was independent of the menopause, and showed the negative relationship to age. These results suggest that muscle-building exercise may have the potentiality to elevate the BMD in the proximal femur in premenopausal women.

Adult↗
PubMed1994

Repression of a malignant cell-substratum adhesion phenotype by inhibiting the production of the anti-adhesive proteoglycan, PG-M/versican.

Malignantly transformed cells usually display a rosette-like morphology of substratum adhesions (called podosomes) and disorganized microfilaments, and are often associated with elevated production of chondroitin sulphate. We previously showed that many tissues and cells express alternatively spliced multiforms of the large chondroitin sulphate proteoglycan termed PG-M (versican is one of the short transcripts). Since PG-M/versican inhibits many types of cell-substratum adhesion and is found to be excluded from focal contacts of cultured fibroblasts, it is likely that this proteoglycan is generally involved in regulating cell-substratum adhesion. We report here that PG-M/versican is selectively excluded from podosomes of human osteosarcoma cells and that specific inhibition of its biosynthesis by an antisense method suppresses such a malignant cell-adhesive phenotype. The results support the idea that PG-M/versican acts as an anti-adhesive molecule and raise the possibility that PG-M/versican controls one type of cancer cell behaviour.

Actin Cytoskeleton↗
PubMed1994

Parabolic flight experiments on physiological data acquisition and processing technologies using small jet aircraft (MU300).

The parabolic aircraft flight provides a short low gravity environment for approximately 20 seconds, which may not be sufficient for a research on the physiological phenomenon induced by actual weightlessness in space. However, the method is still useful to reveal essential and characteristic feature of physiological signs, and is available for testing hardware and also training of crew member during altered gravity. This paper reports the summary of parabolic flight experiments recently conducted as a NASDA program (1990-1992). The program is providing opportunities in low gravity research with small jet aircraft for researchers and agencies. The flight experiments in the life science area have been conducted mostly focused on a physiological changes and basic methodology which may be effective under the altered gravity condition. In this study, the following research team, NASDA, Research Institute of Environmental Medicine, Nagoya University, Toyohashi University of Technology, Tokyo Metropolitan Hospital, Torey Research Center and JSUP were involved and coordinated for the research.

Aircraft↗
PubMed1994

[In situ expression of IL-1 beta and IL-2 mRNA in thymuses from patients with myasthenia gravis].

The expression of IL-1 beta mRNA and IL-2 mRNA was analyzed in seven thymuses from patients with myasthenia gravis (MG) and in three normal thymuses using in situ hybridization techniques. Cells containing IL-beta mRNA were detected in all seven cases. These IL-1 beta producing cells were mainly located and clustered in the connective structures of thymic septae and peri-lobuler area like anti-keratin AE3 positive cells. The distribution of anti-CD68 positive cells was different from that of IL-1 beta producing cells in thymus of myasthenia gravis patients. IL-2 producing cells were also found in all seven cases, and their frequency (number of cells/mm2) had a tendency to correlate with the severity of the disease. On the other hand, we could not find both IL-1 beta mRNA and IL-2 mRNA in three normal thymuses. These results suggested a possible role of high IL-1 beta and IL-2 production to activate T cells in myasthenia gravis thymus. Furthermore, in situ production of IL-2 might be reflected in the severity of the disease.

Adolescent↗
PubMed1994

[The optimal period for orally administered fluoropyrimidines as an adjuvant chemotherapy for gastric cancer--a pilot study using 5-FU tablets compared with surgical operation alone].

Long-term oral administration of fluoropyrimidines such as 5-fluorouracil (5-FU) or tegafur is commonly used as an adjuvant chemotherapy for gastric cancer, but the optimal period or optimal total doses of fluoropyrimidines have not been studied. Two hundred cases of macroscopical Stage II and III curatively resected gastric cancer patients were entered in this study, and divided into three groups (6 months group: mitomycin C was given i.v. at day 0 and day 1 and 5-FU tablets were orally administered at a dose of 200 mg/day for 6 months. 12 months group: MMC was given the same as for the 6 months group and 5-FU tablets were administered for 12 months. Surgery alone group: No chemotherapy, operation only). As the result, 185 cases were eligible. There was no significant difference between the 6 months group and the 12 months group among Stage II patients. Although there was also no significant difference between the 2 groups in Stage III patients, the survival curve of 12 months group was always higher than in the 6 months group. When comparing with surgery alone group, 5-year survival of the 12 months group was always higher than in the surgery alone group of Stage III patients; however, the survival rate in the 6 months group was worse than in the surgery alone group at Stage II and III. These results suggest that MMC i.v. and 12 months or over administration of 5-FU tablets is useful for Stage III gastric cancer patients, and that cooperative study is required comparing with surgery alone in Stage II patients.

Administration, Oral↗
PubMed1994

Vertebral bone-marrow changes in degenerative lumbar disc disease. An MRI study of 74 patients with low back pain.

We carried out MRI studies of 74 patients with end-plate and vertebral bone-marrow changes associated with degenerative lumbar disc disease. Abnormalities were classified into type A, with decreased signal intensities, and type B, with increased signal intensities on T1-weighted spin-echo images. Twenty-seven (73%) of the 37 patients with type-A changes had low back pain, in contrast to only four (11%) of the 37 patients with type-B changes. Lateral flexion-extension radiographs showed hypermobility in 26 patients (70%) with type-A changes, and in only six (16%) with type-B changes. Type-A changes correlated with segmental hypermobility and low back pain, while type-B changes were more common in patients with stable degenerative disc disease.

Adolescent↗
PubMed1993

Tissue variation of two large chondroitin sulfate proteoglycans (PG-M/versican and PG-H/aggrecan) in chick embryos.

PG-M and PG-H, chick large chondroitin sulfate proteoglycans corresponding to versican (fibroblast-type proteoglycan) and aggrecan (cartilage-characteristic proteoglycan), respectively, which are found in mammals, have been characterized in various tissues of chick embryos. Their distribution and the compositions of the core molecules were analyzed by immunofluorescence staining and immunoblotting, respectively, using various monospecific antibodies. Molecules reactive to a monoclonal antibody to the PG-M core protein (designated MY-174) were distributed in various tissues, including aorta, lung, cornea, brain, skeletal muscle and dermis. Immunoblotting with MY-174 of the chondroitinase ABC-digested tissue extracts showed a tissue variation of MY-174-reactive core molecules (550-kD, 500-kD, 450-kD, and 350-300-kD). In contrast, PG-H, besides massive occurrence in cartilage, was only found in a few tissues such as aorta and brain. In addition, PG-H in aorta, cornea, and skin was atypical in structure, because it lacked keratan sulfate. The expression of PG-M in developing chick embryos was then examined. PG-M was found in some developmentally active areas, such as the perinotochordal mesenchyme between notochord and neural tube, the basement membranes facing neuroepithelial cells, and condensing mesenchymal cells in limb buds, suggesting some functions distinctive of the developing tissues.

Aggrecans↗
PubMed1993

Functional anatomy of the posterolateral structures of the knee.

The major supporting structures of the posterolateral knee were noted to be composed of three components: the fabellofibular ligament, the arcuate ligament, and popliteus muscle with origin from fibular head. We classified this area of the knee into seven major anatomic variants. Popliteus tendon is composed of two parts: the anterior and the posterior fibers. The anterior fibers become tight, while the posterior fibers become lax as the knee was flexed. This phenomenon is more pronounced when the tibia is rotated externally. The midpoint between the anterior and the posterior fibers insertions on the femur appeared to be the isometric point of the popliteus tendon.

Biomechanical Phenomena↗