Search PubMed⌕ Search

Biomedical subjects

M Yamagata

Publications and source records attributed to M Yamagata.

At least 127 records · Page 7Linked to original sources
PubMed1993

Three-dimensional motion analysis of the upper cervical spine during axial rotation.

Rotational motion of the normal upper cervical spine was analyzed in 20 men using biplanar roentgenograms, a system digitizer, and a personal computer. To detect the bony landmarks of the atlas, the subjects' heads were fixed and their trunks rotated in the reference frame while these biplanar studies were obtained. Coupling motions observed included 10 degrees extension at C0-C1, with 11 degrees of lateral bending between C1-C2. Almost all (80%) cervical axial rotation took place at C1-C2, whereas only 4 degrees of rotation occurred at C0-C1. Furthermore, as C1-C2 axial rotation increased, so did rotation in the opposite direction at C0-C1 while less rotation was noted below C2. The instantaneous axis of rotation was located anterior to the foramen magnum at the C0-C1 level, in the central portion of the dens at C1-C2.

Adult↗
PubMed1993

Selective distributions of proteoglycans and their ligands in pericellular matrix of cultured fibroblasts. Implications for their roles in cell-substratum adhesion.

We showed previously that a large chondroitin sulfate proteoglycan, PG-M (also known as versican), inhibits cell-substratum adhesion, while basement membrane heparan sulfate proteoglycan (recently named perlecan) does not (Yamagata et al. (1989) J. Biol. Chem. 264, 8012-8018). To extend our understanding of the adhesive function of these proteoglycans, we examined the pericellular localization of the proteoglycans and their ligands and also that of some matrix receptors and cytoskeletal molecules in various fibroblast culture systems. PG-M was abundant in the subcellular space of fibroblasts, but was excluded selectively from focal contacts where vinculin, integrins and fibronectin were localized. Hyaluronan, CD44 and tenascin were distributed similarly as PG-M. In contrast, perlecan was associated with fibronectin and was included in focal contacts. Syndecan-1, a membrane heparan sulfate/chondroitin sulfate proteoglycan, was associated with fibronectin at the cell surface, partly at focal contacts and in association with stress fibers. Thus, complexes of PG-M with hyaluronan, tenascin and CD44, are not involved in focal contacts. On the other hand, perlecan and syndecan-1 together with fibronectin may participate in focal contacts. The difference in localization between these proteoglycans may be related to their glycosaminoglycan content and to their distinctive roles in cell-substratum adhesion.

Animals↗
PubMed1993

Visualisation of symptomatic nerve roots. Prospective study of contrast-enhanced MRI in patients with lumbar disc herniation.

We studied the use of gadolinium diethylenetriaminepentaacetic acid-enhanced MRI in the detection of pathological changes in the nerve roots of 25 patients with unilateral sciatica due to lumbar disc herniation. Enhancement was observed in the affected nerve roots within the root sleeve at the caudal edge of the herniation and was classified into three categories: grade 0, none; grade 1, enhancement restricted to a focal region within the sleeve; and grade 2, diffuse and homogeneous. The grade of enhancement correlated well with the severity of the sciatica, and was considered to be due to a disruption of the blood-nerve barrier, leading to oedema.

Adolescent↗
PubMed1993

Possibility of hepatic resection in patients on maintenance hemodialysis.

A review of seven hepatic resections in six patients undergoing maintenance hemodialysis is presented. These cases consisted of hepatocellular carcinoma in four, and cholangiocellular carcinoma, myelolipoma and focal nodular hyperplasia in one each. The last preoperative hemodialysis was undertaken within 24 h prior to the operation with heparin. Intraoperatively, infused solutions containing no potassium, along with strict attention to preventing overhydration, allowed us to manage the patients without hemodialysis on the day of the operation. No specific intra-operative complications related to hemodialysis were noted. Postoperative hemodialysis was performed on the first or second day after operation, using nafamstat mesilate, a synthetic protease-inhibiting agent. The morbidity rate in the hemodialyzed patients was 85.7% (6/7), which was significantly higher than that in the non-hemodialyzed patients who underwent hepatic resections in our hospital. Fluid collection in the pleural and/or peritoneal cavities was frequent and difficult to control, but transient. Our experience suggests that hepatic resection is an acceptable procedure for hemodialyzed patients, when used in conjunction with careful perioperative management.

Adenoma, Bile Duct↗
PubMed1993

Liver resection and intractable postoperative ascites.

Among 211 patients who, between 1985 and 1990, underwent liver resection in Kyushu University Hospital, uncontrollable ascites occurred in 53 (25%). A univariate analysis revealed that postoperative death with liver failure occurred more frequently in patients with intractable ascites (p < 0.05). Alanine amino transferase levels were significantly higher in patients with intractable ascites (p < 0.05), but serum bilirubin, alkaline phosphatase and serum albumin levels did not differ significantly. Portal pressure (p < 0.05), the operation time (p < 0.01) and blood loss (p < 0.01) were significantly higher in patients with intractable postoperative ascites. A multiple analysis showed a correlation between the operation time, portal hypertension and postoperative intractable ascites. Postoperative histology revealed that a larger number of patients with cirrhosis had intractable ascites (p < 0.05). We conclude that cirrhosis, portal pressure and operating time are the most important factors related to intractable ascites in the case of hepatectomy. Areas of the liver to be resected should be limited in cirrhotic patients with portal hypertension.

Adult↗
PubMed1992

Simplified hilar division in controlled right hepatectomy.

Right hepatectomy with preliminary vascular control at the hepatic hilus could be performed not by the method of dividing the structures in the hepatoduodenal ligament separately but instead by simultaneously employing both the hemihepatic vascular control method and the ultrasonic dissector. When applying the tape around the first portal pedicle, the anterior and posterior portal pedicles are easily exposed by using the ultrasonic dissector and, thereafter, ligated and cut; by utilizing this simplified hilar division, hemostasis of the right hepatic lobe can be achieved.

Hepatectomy↗
PubMed1992

Mechanical stability of the pedicle screw fixation systems for the lumbar spine.

Five different pedicle screw systems: AO Fixator Interne, VSP Steffee plate, Luque ISF, modified Zielke, and Chiba-type plate screw system (experimental device), were evaluated for biomechanical strength. A fatigue test for the screw, compressive, and torsional tests for the pedicle screw systems and a pull-out test of the pedicle screw were done. Even the Schanz screw, which showed the highest endurance limit, may be broken under the continuous loading condition in the body. The AO Fixator Interne and Steffee plate system themselves are rigid and are indicated for injuries that need reduction. The Luque ISF, modified Zielke, and Chiba-type plate screw systems, however, are indicated for degenerative lumbar disease requiring in situ fusion. There was a linear positive correlation between the bone mineral density of the vertebral body and the pull-out strength of the pedicle screw (correlation coefficient, 0.68). The fixation strength of the pedicle screw to the bone decreased remarkably in osteoporosis.

Biomechanical Phenomena↗
PubMed1992

The difference in chemosensitivity to antineoplastic agents of human hepatocellular carcinoma cells under normo-oxygenated or hypoxic conditions.

In order to select more effective drugs under hypoxia for the treatment of hepatocellular carcinoma, the cytotoxicity of antineoplastic agents for two hepatoma cell lines, PLC/PRF/5 and HuH-7, was examined under both oxygenated and hypoxic conditions. Mitomycin C was observed potentially to have enhanced cytotoxicity under hypoxic conditions for both hepatoma cell lines. Carboquone showed enhanced cytotoxicity under hypoxia for PLC/PRF/5 alone. On the other hand, there was no cytotoxic enhancement of adriamycin or cisplatin in either cell line. Thus, the sensitivity of tumour cells to the cytotoxic agents altered according to the conditions to which the tumour was exposed. The selection of the antineoplastic drugs for chemotherapy therefore should depend not only on the sensitivity of individual tumours to various drugs, but the alteration of the cytotoxicity of the drugs under certain conditions should also be carefully taken into account.

Antineoplastic Agents↗
PubMed1991

Distribution and therapeutic effect of intraarterially transferred tumor-infiltrating lymphocytes in hepatic malignancies. A preliminary report.

Indium-111-labeled tumor-infiltrating lymphocytes (111In-TIL) were transferred as an intrahepatic arterial bolus to determine their in vivo distribution in patients with hepatic malignancies. In the in vitro culture system, TIL were expanded upon simultaneous stimulation by recombinant interleukin-2 (rIL-2) and immobilized anti-CD3 monoclonal antibody. This double activation led not only to a larger cell yield, but also to a significantly more dominant subpopulation with CD4+ phenotype than occurred with activation by rIL-2 alone. Accumulations of 111In-TIL in the liver were identified by scintigraphy in all of three patients, corresponding to the tumor localization by computed tomography. Such accumulation had persisted for at least 48 hours after infusion. After intraarterial chemoimmunotherapy that included TIL, two of three patients achieved a partial therapeutic response. The authors conclude that their method of culture and transfer can facilitate the accumulation of TIL at tumor sites, which may augment the antitumor effects of adoptive immunotherapy.

Adenocarcinoma↗
PubMed1991

Management of haemangioma of the liver: comparison of results between surgery and observation.

Cavernous haemangioma of the liver was diagnosed in 33 patients using hepatic angiography between 1978 and 1988. Thirteen of these patients underwent surgery. There were no deaths after operation; morbidity included upper gastrointestinal bleeding in two patients and liver dysfunction in one. The follow-up study showed no evidence of recurrence in any of the 13 patients up to 143 months after operation. In the operated patients, a small haemangioma was left in the liver of two for anatomical reasons, but the size of these tumours showed no change over 3 years. The remaining 20 patients had no specific treatment for haemangioma and were followed up for between 18 months and 8 years. Of these 20 patients, 19 had tumours of less than 5 cm in size. As there was no enlargement or rupture of haemangiomas of less than 5 cm, it was felt that these could be observed. Cases having a potential for exposure to trauma, rapid tumour growth, or displaying severe symptoms should be considered for surgical treatment; this can be justified due to low morbidity and no mortality.

Female↗
PubMed1991

The dynamics of compartmentalization of embryonic muscle by extracellular matrix molecules.

In order to delineate the role of proteoglycans in muscle development, the immunohistological localization of glycosaminoglycans and proteoglycan core proteins was studied in embryonic chick leg at Hamburger-Hamilton stages (St.) 36, 39, 43, and 46, and at 2 weeks posthatching. A specific anatomical landmark was chosen (the junction between the pars pelvica and the pars accessoria of the flexor cruris lateralis muscle) in order to ensure the study of anatomically equivalent sites. Frozen cross sections were immunostained with monoclonal antibodies to chondroitin-4-sulfate, chondroitin-6-sulfate, dermatan sulfate, and keratan sulfate glycosaminoglycans; to the core proteins of muscle/mesenchymal chondroitin sulfate proteoglycan, dermatan sulfate proteoglycan, and basement membrane heparan sulfate proteoglycan; and to laminin and tenascin. Extracellular matrix zones corresponding to the endomysium, perimysium, epimysium, basement membrane, and myotendinous junction each show characteristic immunostaining patterns from St. 36 to St. 46 and have unique matrix compositions by St. 46. In some cases, there is a sequential or coordinate expression of epitopes, first in the epimysium, then the perimysium, and last in the endomysium. Dermatan sulfate proteoglycan is detected in the epimysium at St. 36, in the perimysium at St. 39 (there is no perimysium structure at St. 36), and is not detected in the endomysium until St. 43. A putative mesenchymal proteoglycan core protein (reactive to the monoclonal antibody MY-174) is detected at St. 39 in both epimysium and perimysium, but is not detected in the endomysium until St. 43. Keratan sulfate antibody immunostains epimysium at St. 39 and perimysium at St. 46, but is never detected in the endomysium. Some epitopes are expressed independently in each of the extracellular matrix zones: antibody to tenascin stains only a subset of the epimysium, at the myotendinous junction; and heparan sulfate proteoglycan and laminin are detected only in the endomysium. Between St. 36 and St. 39, the muscle/MY-174-reactive proteoglycan core protein staining decreases in intensity in the endomysium and becomes positive in the epimysium and perimysium. An inverse relationship is found between (1) the disappearance of muscle/MY-174-reactive proteoglycan core protein staining at the surface of myotubes from St. 36 to St. 39 and (2) the infiltration of laminin and heparan sulfate proteoglycan staining encompassing groups of myotubes (St. 36) to circumferential staining of all myotubes (St. 39).(ABSTRACT TRUNCATED AT 400 WORDS)

Aggrecans↗
PubMed1991

The complete primary structure of type XII collagen shows a chimeric molecule with reiterated fibronectin type III motifs, von Willebrand factor A motifs, a domain homologous to a noncollagenous region of type IX collagen, and short collagenous domains with an Arg-Gly-Asp site.

Extracellular matrix molecules are generally categorized as collagens, elastin, proteoglycans, or other noncollagenous structural/cell interaction proteins. Many of these extracellular proteins contain distinctive repetitive modules, which can sometimes be found in other proteins. We describe the complete primary structure of an alpha 1 chain of type XII collagen from chick embryonic fibroblasts. This large, structurally chimeric molecule identified by cDNA analysis combines previously unrelated molecular domains into a single large protein 3,124 residues long (approximately 340 kD). The deduced chicken type XII collagen sequence starts at the amino terminus with one unit of the type III motif of fibronectin, which is followed by one unit homologous to the von Willebrand factor A domain, then one more fibronectin type III module, a second A domain from von Willebrand factor, 6 units of type III motif and a third A domain, 10 consecutive units of type III motif and a fourth A domain, a domain homologous to the NC4 domain peptide of type IX collagen, and finally two short collagenous regions previously described as part of the partially sequenced collagen type XII molecule; an Arg-Gly-Asp potential cell adhesive recognition sequence is present in a hydrophilic region at the terminus of one collagenous domain. Antibodies raised to type XII collagen synthesized in a bacterial expression system recognized not only previously reported bands (220 kD et cetera) in tendons, but also bands with apparently different molecular sizes in fibroblasts and 4-d embryos. The antibodies stained a wide variety of extracellular matrices in embryos in patterns distinct from those of fibronectin or interstitial collagens. They prominently stained extracellular matrix associated with certain neuronal tissues, such as axons from dorsal root ganglia and neural tube. These studies identify a novel chimeric type of molecule that contains both adhesion molecule and collagen motifs in one protein. Its structure blurs current classification schemes for extracellular proteins and underscores the potentially large diversity possible in these molecules.

Amino Acid Sequence↗
PubMed1991

[A case of colon cancer with severe anal bleeding caused in a preoperative chemotherapy].

UFT was orally administered at a dose of 600 mg/day as a preoperative chemotherapy for a 44-year old male with colon cancer. On the seventh day of the administration, severe anal bleeding occurred, and an emergent colectomy was performed. The macroscopic findings of the resected tumor were different from the first endoscopic picture, and the histopathological findings showed the significant effects of preoperative chemotherapy.

Adenocarcinoma↗
PubMed1991

Modified technique of Pringle's maneuver in resection of the liver.

Crushing of the hepatic parenchyma with hepatic clamps to minimize blood loss during resection of the liver leads to mechanical damage of hepatocytes. Pringle's maneuver may precipitate liver failure by hepatic warm ischemia as well. Therefore, we controlled bleeding from the surface of the resection by using light compression on the hepatic parenchyma with a band while applying a hepatic arterial clamp at the hepatic hilus. This vascular control method can be done because the portal pressure is about one-tenth of the hepatic artery pressure and provides an efficient and harmless transection of the liver.

Animals↗
PubMed1990

Clinicopathologic features of hepatocellular carcinoma in young patients.

To investigate clinicopathologic characteristics of hepatocellular carcinoma (HCC) in young adults, excised tumors from 21 patients younger than 45 years (young group) were compared with findings in tumors from 204 patients older than 45 (old group). In the young group HCC showed (1) a high incidence of positive hepatitis B virus surface antigen (HBsAg) (young 71.4% versus old 20.1%); (2) relatively well-preserved hepatocellular function (indocyanine green test; young 10.7 +/- 8.8% versus old 20.6 +/- 10.8%); (3) low incidence of histologically verified concomitant cirrhosis (young 52.4% versus old 78.4%); and (4) a more advanced stage of the disease in TNM classification (Stage III; young 52.4% versus old 18.1%). With respect to survival rates achieved by surgery, there was no statistically significant difference between the two groups. Thus, hepatitis B virus may relate to the occurrence of HCC in the young patients. Despite the advanced stage in the young group, survival rate after surgery was comparable with that achieved in the old group. These observations mean that a close periodic surveillance of young adults with a positive HBsAg is required to detect HCC at an early stage. Treatment of patients with HBsAg using interferon or vidarabine and hepatitis B vaccine should be made to convert HBsAg to negative in these individuals.

Adult↗
PubMed1990

The distribution of mesenchyme proteoglycan (PG-M) during wing bud outgrowth.

This study utilizes immunofluorescence to describe the distribution of several extracellular matrix molecules in the chick embryo during the process of limb outgrowth and the formation of precartilage condensations. A large chondroitin sulfate proteoglycan (PG-M) is detected at the wing level at Hamburger and Hamilton stage 14 in and under the dorsal ectoderm, and is associated with the basement membranes around the neural tube, notochord and pronephros, but not with other basement membranes. The galactose-specific lectin, peanut agglutinin (PNA), has a similar distribution except that it also binds to the dorsal side of the neural tube. PG-M is not detected in the limb mesenchyme until after stage 17, when it is present in the distal region, as is PNA-binding material. With further development of the wing bud, PG-M is present in the subectodermal mesenchyme, the mesenchyme at the distal tip and in the prechondrogenic core. After stage 22 PNA-binding material becomes localized in the prechondrogenic core, the basement membranes under the apical ectodermal ridge, and the ventral sulcus. The distribution of these components (PG-M and PNA binding material) overlaps, but differs from that of type I collagen and fibronectin and basement membrane components, such as laminin, basement membrane heparan sulfate proteoglycan, and type IV collagen. Tenascin, on the other hand, is not detected in the limb bud until stage 25, after the appearance of cartilage matrix components such as type II collagen and cartilage proteoglycan (PG-H). These results are considered in relation to the formation of precartilage aggregates, and indicate that PNA binds to components in precartilage aggregates other than PG-M or tenascin.

Aggrecans↗
PubMed1990

Long-term results of anterior interbody fusion for treatment of degenerative spondylolisthesis.

Thirty-nine patients, 34 women and five men, underwent anterior decompression and interbody fusion for degenerative spondylolisthesis between February 1958 and August 1988. Their average age at surgery was 51 years (range, 34-74 years), and their average follow-up period was 12 years 7 months (range, 6 months to 30 years). Clinical evaluation was done by the score rating system of the Japanese Orthopaedic Association (JOA Score). Patients with JOA scores of 25 points or more were rated as "satisfactory." Survivorship was analyzed by the method of Kaplan and Meier to determine the cumulative percentage of patients with satisfactory results. The following results were obtained: Seventy-six percent of the patients had satisfactory results for 10 years after the anterior interbody fusion, 60% for 20 years, and 52% for 30 years. Irrespective of their age at surgery, the patients generally maintained satisfactory results up to 65 years of age.

Female↗