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S Yamagata

Publications and source records attributed to S Yamagata.

At least 91 records · Page 5Linked to original sources
PubMed1994

Different clinicopathologic findings in two histologic types of carcinoma of papilla of Vater.

The aim of this study was to investigate the differences between the clinicopathological findings in two histologic types of carcinoma of the papilla of Vater. We histologically classified carcinoma of the papilla into two types: 1) an intestinal type that resembles tubular adenocarcinoma of the stomach or colon, and 2) a pancreaticobiliary type that is characterized by papillary projections with scant fibrous cores. We examined 53 cases of resected carcinoma of the papilla. The intestinal-type carcinomas were similar to the intestinal mucosa in that they had lysozyme-containing, Paneth or argyrophil cells, as demonstrated by the immunohistochemically positive stainings for the anti-lysozyme antibody. Although both the sizes of the two types of carcinomas and the age distributions of cases with the two types of carcinoma were almost the same, the prognosis of the cases with the intestinal type was much better than that of the cases with the pancreaticobiliary type. Histological lymph node metastasis was found significantly more often in the pancreaticobiliary type. This result was supported by the fact that small carcinomas of the intestinal type showed little or no invasion into the surrounding interstitium, as opposed to the pancreaticobiliary type, which had a strong infiltrative tendency. The pathogenesis of carcinoma of the papilla of Vater should be further evaluated, taking into consideration the existence of these two histologic types.

Adult↗
PubMed1994

[Long-term administration of carmofur as a post-operative adjuvant chemotherapy for cervical adenocarcinoma. Cervical Adenocarcinoma Cooperative Research Association].

Cervical adenocarcinoma and adenosquamous cell carcinoma are low in radiation sensitivity, and the prognosis is said to be inferior to that of squamous cell carcinoma. Eleven facilities nationwide participated in the historical control study on the recurrence prevention effect of carmofur (HCFU) administered at 300 mg/day for more than two years postoperatively as an adjuvant chemotherapy to patients with cervical adenocarcinoma or adenosquamous cell carcinoma for which radical operation is possible. Registered for the study was a total of 252 patients: 77 patients for whom administration of carmofur was begun during the period from January 1987 and March 1989, 71 patients (control 1) who were treated for the cancer after January 1982 but did not receive adjuvant chemotherapy, and 104 patients who received adjuvant chemotherapies with other than carmofur (control 2). In analyses with the Kaplan-Meier method, the carmofur administration group demonstrated a better cumulative survival rate and disease free rate than control 1 (no adjuvant chemotherapy), suggesting carmofur was effective in preventing the recurrence of cervical adenocarcinoma and adenosquamous cell carcinoma.

Adenocarcinoma↗
PubMed1993

Cloning and bacterial expression of the CYS3 gene encoding cystathionine gamma-lyase of Saccharomyces cerevisiae and the physicochemical and enzymatic properties of the protein.

By screening a yeast genomic library, we isolated and characterized a gene rescuing the cysteine requirement in a "cys1" strain of Saccharomyces cerevisiae. Except for four residues in the open reading frame composed of 1,182 nucleotides, the DNA sequence was the same as that for the CYS3 (CYI1) gene, encoding cystathionine gamma-lyase (EC 4.4.1.1), and isolated previously as a cycloheximide-induced gene (B. Ono, K. Tanaka, K. Naito, C. Heike, S. Shinoda, S. Yamamoto, S. Ohmori, T. Oshima, and A. Toh-e, J. Bacteriol. 174:pp.3339-3347, 1992). S. cerevisiae "cys1" strains carry two closely linked mutations; one (cys1) causes a defect in serine O-acetyltransferase (EC 2.3.1.30), and another, designated cys3, impairs cystathionine gamma-lyase activity. Rescue of the cysteine requirement by the gene encoding cystathionine gamma-lyase is consistent with both defects being responsible for the cysteine auxotrophy. In an effort to further determine the physicochemical and enzymatic properties of this enzyme, a coding fragment was cloned into an Escherichia coli expression plasmid, and the protein was produced in the bacteria. The induced protein was extracted by sonication and purified to homogeneity through one course of DEAE-cellulose column chromatography. The yield of the protein was approximately 150 mg from cells cultured in 1 liter of L broth. The protein showed molecular weights of approximately 194,000 and 48,000 (for the subunit), suggesting a tetrameric structure. An s20,w value of 8.8 was estimated by centrifugation in a sucrose concentration gradient. No sulfhydryl groups were detected, which is consistent with the absence of cysteine residues in the coding sequence. The isoelectric point was at pH 5.2. The protein showed a number of cystathionine-related activities, i.e., cystathionine beta-lyase (EC 4.4.1.8), cystathionine gamma-lyase, and cystathionine gamma-synthase (EC 4.2.99.9) with L-homoserine as substrate. In addition, we demonstrated L-homoserine sulfhydrylase (adding H2S) activity but could find no detectable serine O-acteyltransferease activity. In this paper, we compare the enzymatic properties of the protein with those of homologous enzymes previously reported and discuss the possibility that this enzyme has a physiological role as cystathionine Beta-lyase and cystathionine gamma-synthase in addition to its previously described role as cystathionine gamma-lyase.

Acetyltransferases↗
PubMed1993

Clinical experience with expanded polytetrafluoroethylene sheet used as an artificial dura mater.

Dural repair using chemically treated cadaveric dura mater often results in atrophic and fragile change of the substitute as well as adhesion between the dura mater and brain surface at reoperation. Creutz-feldt-Jakob disease has occurred after repair using cadaveric dura mater. Expanded polytetrafluoroethylene (EPTFE) surgical sheet was used for dural repair in 34 patients. Suturing of EPTFE was easy and the incidence of cerebrospinal fluid accumulation in the epidural space was the same as when cadaveric dura mater was used. Six patients underwent reoperation, 1-15 months after the first operation. At reoperation the EPTFE sheet showed no change except for becoming transparent, and the strength was well preserved. A very thin layer of granulation tissue was formed between the EPTFE sheet and brain surface, but the EPTFE sheet was easily detached from the brain surface without adhesion even 15 months after the first operation. Our results suggest that the EPTFE sheet can be used safely and effectively as an artificial dura mater.

Brain Diseases↗
PubMed1993

Comparative studies on O-acetylhomoserine sulfhydrylase: physiological role and characterization of the Aspergillus nidulans enzyme.

O-acetylhomoserine sulfhydrylase (OAH SHLase) from Aspergillus nidulans is an oligomeric protein with a broad substrate specificity with regard to sulfhydryl compounds. As its Saccharomyces cerevisiae counterpart the enzyme also reacts with O-acetylserine and is inhibited by carbonyl reagents but not by antiserum raised against the yeast enzyme. In contrast to Saccharomyces cerevisiae the enzyme is not essential for Aspergillus nidulans as indicated by the completely prototrophic phenotype of OAH SHLase-negative mutants. Its major physiological role in Aspergillus nidulans seems to be recycling of the thiomethyl group of methylthio-adenosine but it is also a constituent of the alternative pathway of cysteine synthesis.

Aspergillus nidulans↗
PubMed1993

[Delayed cerebral dysautoregulation after recirculation of cerebral ischemia].

Sequential changes of cerebral autoregulation were studied in 20 cats after recirculation of cerebral ischemia. The cerebral autoregulation was evaluated by autoregulation index (A.I.), calculating % delta cerebral blood flow (CBF)/delta cerebral perfusion pressure (CPP), with changing the mean arterial blood pressure (MABP) within 80-130 mmHg. Duration of ischemic insult was 15 min after disappearance of direct cortical response (DCR). Following recovery of cerebral circulation, MABP, CBF and intracranial pressure (ICP) were observed sequentially for at least 48 hours. In 6 of 20 cats the autoregulation was disturbed early after recirculation, and the ICP was increased, resulting in no cerebral blood flow (early deteriorated group). In the other 14 cats the autoregulation was restored immediately, but in 7 of the 14 cats it was disturbed again after 24 hours following recirculation (delayed deteriorated group), finally the ICP was elevated and the CBF became 0 as same as early deteriorated group. In another 7 cats it was not disturbed until 5 days. The changes in CBF following insult were five patterns. These were classified into type A (Gradual decrease), type B (Transient increase), type C (Constant maintenance), type D (Relatively rapid decrease) and type E (Rapid decrease). The delayed cerebral dysautoregulation occurred in the types except for type A and type E. These results suggested there was close relation between delayed dysautoregulation and delayed neuronal dysfunction that we reported previously. Moreover, we considered the delayed dysautoregulation could be speculated from the value of ICP/CBF immediately after recirculation and the pattern of the changes in CBF during ischemic insult.

Animals↗
PubMed1992

The collagen receptor alpha 2 beta 1, from MG-63 and HT1080 cells, interacts with a cyclic RGD peptide.

Several receptors for the extracellular matrix protein collagen have been described which belong to the superfamily of receptors collectively known as integrins. Although several integrins have been shown to interact with extracellular matrix molecules via a common recognition site, arginine-glycine-aspartic Acid (RGD), within the beta 1 integrin subfamily, only the fibronectin receptor (alpha 5 beta 1) has been convincingly shown to interact with RGD. In the present study, we tested whether a collagen receptor could interact with RGD. Adhesion of an osteosarcoma cell line, MG-63, to immobilized collagen I was inhibited by the cyclic RGD-containing peptide, C*GRGDSPC* (where C* indicates that Cys participates in disulfide), and not by the linear GRGDSP or the non-RGD-containing cyclic peptide, C*GKGESPC*. Similarly, using collagen-Sepharose affinity chromatography, a heterodimeric protein could be specifically eluted from the column by the cyclic RGD peptide. Immunoprecipitations of the eluted material with monoclonal antibodies showed reactivity with the collagen receptor alpha 2 beta 1 and not alpha 3 beta 1. Our data demonstrate that RGD peptides can interact with the collagen receptor, and the differences seen with the linear and cyclic peptide suggest that the cyclic C*GRGDSPC* has a higher avidity for the receptor than the more flexible linear GRGDSP. In this paper, we provide supportive evidence that one possible mode of collagen interaction with alpha 2 beta 1 is via the RGD recognition sequence.

Amino Acid Sequence↗
PubMed1992

A case of treatment-related leukoencephalopathy: sequential MRI, CT and PET findings.

A case of treatment-related leukoencephalopathy is presented. A patient with medulloblastoma was postoperatively treated with craniospinal axis irradiation. One month after irradiation, weekly intrathecal administration of methotrexate was performed 4 times to treat cerebrospinal fluid dissemination of the tumor. Two months after the initiation of intrathecal chemotherapy, the patient became somnolent and developed decerebrate posturing. Magnetic resonance imaging showed diffuse leukoencephalopathy. Positron emission tomography revealed a diffuse decrease in glucose uptake in the deep white matter. Auditory evoked potential also showed diffuse abnormalities, not only in the cerebrum, but also in the brain stem. High dose intravenous leucovorin rescue was attempted without any neurologic improvement.

Blood Proteins↗
PubMed1992

The introduction of microvascular surgery to hepatic artery reconstruction in living-donor liver transplantation--its surgical advantages compared with conventional procedures.

Microvascular surgery for the reconstruction of the graft artery has been used since the 8th case in our series of 14 liver transplantations using living-related donors, and the clinical results have been compared between the first seven cases (the Loupe group) and the last seven cases (the Micro group). Seven arteries in 7 grafts were reconstructed with the use of loupe magnification in the Loupe group, while 8 arteries in 7 grafts were anastomosed with microscopic techniques in the Micro group. Statistically, there was no difference between the two groups in general background, including age, body weight and primary disease of the recipient, and in medical and surgical factors possibly relating to postoperative thrombosis of the hepatic artery. In two cases in the Loupe group, one or two additional reconstructions were necessary to obtain sufficient blood flow, while 8 arteries were anastomosed in the Micro group without any arterial complication in the postoperative period. There was no difference in time required for completing the arterial reconstruction (45.1 +/- 18.1 min in the Loupe versus 44.4 +/- 6.9 min in the Micro [mean +/- SEM]). Postoperative ultrasonic Doppler duplex study demonstrated a temporary decrease in the arterial flow in 2 cases of the Loupe group, and partial thrombosis of the artery was suspected. Additionally there were two episodes of hepatic artery thrombosis in 1 case of the Loupe group, in which emergent revision for thrombectomy and reanastomosis was performed at the first episode. This illustrated the higher incidence of arterial complications in the Loupe group compared with the Micro group (4 episodes/7 arteries in the Loupe versus 0/8 arteries in the Micro, P less than 0.05). In the present series there were no graft failures or arterial complications in the three deaths in the series. The clinical improvements achieved by microvascular surgery in living-donor liver transplantation suggest an alternative technical strategy for dealing with problematic arterial reconstruction in adult liver transplantation.

Child↗
PubMed1992

[A case of posterior choroidal artery infarction].

The posterior choroidal artery supplies the lateral geniculate body, the posterior thalamus and the caudate body. Currently, a few cases of infarction in this arterial territory have been reported. This is a case of 59-year-old male, exhibiting left homonymous hemianopsia and left hemiparesis. Clinically it was impossible to make a diagnosis of infarction in this area. We were able to determine that it was a posterolateral choroidal artery infarction rather than an anterior choroidal artery infarction using 1.5 T-magnetic resonance imaging (MRI). The MRI scan clearly disclosed the areas of infarction, which included the lateral geniculate body, the posterior thalamus and the caudate nucleus body. Additionally, cerebral angiography revealed an occluded proximal portion of the right posterior cerebral artery (P2) and a patent right anterior choroidal artery. Anatomically, the areas surrounding the lateral geniculate body are supplied by both the anterior and the posterolateral choroidal arteries. However, the posterolateral choroidal artery infarctions are believed to be rare due to usual dominance of the anterior choroidal artery. Presently, with the use of MRI scanning, these areas can be easily visualized. Therefore, the posterolateral choroidal artery infarction can be diagnosed more easily. It is conceivable that more cases will be accurately diagnosed using this tool.

Cerebral Angiography↗
PubMed1992

[Investigation of the therapeutic use of proton pump inhibitor (PPI) by measurement of 24 hour the intra-gastric pH].

The intragastric acidic condition were examined over 24 hours in 13 healthy volunteers to compare the inhibitory effect of PPI and of H2-antagonist on the acid secretion. Both PPI 15 mg and PPI 20 mg showed a stronger action on the acid inhibition than H2-antagonists. The morning PPI (20 mg) administration inhibited the acid secretion from noon the first day, and showed an even stronger effect on the fourth day (total PPI 80 mg). Evening PPI administration showed poorer effects than the morning. However, of this was due to a difference in the inhibitory effect in the daytime. The evening PPI administration showed effective acid inhibition at night, and nocturnal intra-gastric pH inversion appeared. It is suggested that the evening PPI administration is more suitable both the ulcer-healing and food digestion in the curative stage.

Adenosine Triphosphatases↗
PubMed1991

Effects of transient forebrain ischemia and reperfusion on function of dopaminergic neurons and dopamine reuptake in vivo in rat striatum.

To clarify functional changes of dopaminergic neurons and dopamine (DA) reuptake during and after ischemia, extracellular DA levels in striatum were determined using in vivo brain microdialysis in a 4-vessel occlusion model of male Wistar rats with and without pharmacological interventions. Without interventions, the extracellular DA levels markedly increased during ischemia, but upon reperfusion, rapidly returned to control level. Infusion of tetrodotoxin, a blocker of voltage-dependent Na+ channels, was without effect on the DA surge during ischemia, but decreased the DA levels after reperfusion to the same extent as in control rats. Pretreatment with nomifensine, an inhibitor of DA reuptake, was also without effect on the surge, but reduced the rate of DA decline after reperfusion to one-fifth of the rate without the pretreatment. When nomifensine was administered 40 min after reperfusion, extracellular DA levels increased to the same extent as in control rats. Infusion of high K+ 1 h after reperfusion induced a smaller increase in extracellular DA levels than that in control rats. It took 96 h for this reduced response to high K+ stimulation to recover after reperfusion. These results suggest that the DA surge during ischemia is mainly derived from action potential-independent DA release (means dysfunction of dopaminergic neurons), although activity of DA reuptake is completely inhibited. After reperfusion, the basal function of dopaminergic neurons and activity of DA reuptake rapidly recover, but the neurons are functionally disturbed to release less DA in response to a given stimulus for several days.

Animals↗
PubMed1991

Occurrence of an active form of gelatinase in human gastric and colorectal carcinoma tissues.

Profiles of gelatinase released during 4 h incubation of explants from human carcinoma tissues (15 gastric and 15 colorectal carcinomas) in serum-free RPMI 1640 medium were compared with those of corresponding normal tissue specimens obtained 2 and 10 cm apart from tumor periphery. All the culture supernatants of both tumor and normal tissues contained gelatinase species of 200, 130, 92 and 72 kDa as detected by zymography with gelatin as a substrate. Besides these gelatinase species, all carcinoma tissue culture supernatants had an additional 66-kDa gelatinase, an active form of the 72-kDa gelatinase. This gelatinase was not detectable in the normal tissues 10 cm apart from the tumor mass, with an exceptional case of gastric carcinoma of Borrmann type 4. These results suggest that the presence of active form of gelatinase might be one of the characteristic properties of these malignant human tumors.

Colorectal Neoplasms↗
PubMed1991

Fibronectin augments anti-CD3-mediated IL-2 receptor (CD25) expression on human peripheral blood lymphocytes.

The extracellular matrix (ECM) is composed of a number of macromolecules that promote cell adhesion, cell migration, and differentiation. Receptors for these molecules have been identified and belong to a superfamily of cell surface proteins, collectively known as the integrins. In this study, we show that the matrix protein fibronectin (FN) acts synergistically with immobilized anti-CD3 antibody to promote proliferation of total human peripheral blood lymphocytes (HPBL) in the absence of exogenous IL-2. Proliferation was inhibited by both the alpha 5 beta 1 and alpha 4 beta 1 recognition peptides. ARG-GLY-ASP (RGD), and GLU-ILE-LEU-ASP-VAL-PRO-SER-THR (EILDVPST), respectively. Expression of CD25 (IL-2 receptor) was significantly higher on cells cultured on anti-CD3 and FN, indicative of T-cell activation. Additionally, cells cultured on immobilized anti-CD3 and FN for 3 days showed increased adhesion to FN and increased forward light scatter/side scatter profile. Synthesis of both IL-1 and to a lesser extent IL-2 was elevated in supernatants from cultures containing both anti-CD3 and FN. These data are consistent with published reports which demonstrate that ECM proteins can act as costimulants of lymphocyte proliferation. Finally, our results show that cells cultured on anti-CD3 antibody and FN have an activated phenotype and that cytokines may be involved in this process.

Antibodies↗
PubMed1991

Establishment and characterization of a new spontaneous metastasis model of human gastric carcinoma in nude mice.

A poorly differentiated medullary carcinoma of human stomach, designated HY-1, was successfully transplanted to nude mice by either the subcutaneous or intramuscular route for five generations. The transplanted tumor showed spontaneous lung metastases in nearly 100% of KSN and Balb/c female nude mice. There were over 20 visible lung metastatic nodules in KSN and Balb/c nude mice bearing tumors for over 80 days. Immunostaining of type IV collagen and electron microscopy revealed that tumor cells were often in direct contact with basement membrane (BM) of tumor blood vessels in the primary tumor tissue. At the site of contact between tumor cells and vascular BM, focal disappearance of the BM, disruption of endothelial cells and entry of tumor cell clusters into vascular lumen were observed. Immunostaining of 72 kDa gelatinase/type IV collagenase demonstrated that tumor cells expressed this enzyme in their cytoplasm. These results suggest that spontaneous metastasis of this tumor may be partly due to a marked tendency to vascular invasion involving the following sequential events: tumor cell contact with vascular BM, BM degradation possibly by 72 kDa gelatinases and endothelial disruption. This model could be a useful tool for understanding the mechanism of hematogenous metastasis of human gastric cancer.

Aged↗
PubMed1991

Effects of hypoxia on the activity of the dopaminergic neuron system in the rat striatum as studied by in vivo brain microdialysis.

The purpose of the present study is to clarify the effects of hypoxia on the activity of the dopaminergic neurons in the brain and its mechanism of action. For this purpose, the effects of hypoxia on the extracellular levels of 3,4-dihydroxyphenylethylamine (dopamine) were examined in the rat striatum using in vivo brain microdialysis in the presence or absence of pretreatment with either tetrodotoxin (a blocker of voltage-dependent sodium channels) or nomifensine (a blocker of dopamine reuptake). Exposure to various degrees of hypoxia (15, 10, and 8% O2 in N2) increased dopamine levels in striatal dialysates to 200, 400, and 1,100%, respectively, of the control value. On reoxygenation, dopamine levels in the dialysates rapidly returned to the control level. Reexposure to hypoxia increased the dopamine levels to the same extent as during the first exposure. After addition of tetrodotoxin (40 microM) to the perfusion fluid or pretreatment with nomifensine (100 mg/kg, i.p.), exposure to hypoxia no longer increased the dopamine levels. These results suggest that although hypoxia induces an increase in the extracellular dopamine levels (hence, an apparent increase in the activity of the dopaminergic neurons), this increase is not the result of an increase in dopamine release itself, but rather the result of inhibition of the dopamine reuptake mechanism.

Animals↗
PubMed1991

[Clinicopathological, ultrastructural and immunohistochemical study on adenoma malignum of the uterine cervix].

A histological, cytological, immunohistochemical and electron microscopical study has been made on 9 cases of adenoma malignum of the cervix. Five patients out of 9 who received surgical treatment following correct diagnosis, and were followed by maintenance chemotherapy with tegafur have survived without evidence of recurrence for 15 to 60 months. The remaining 4 patients who were treated following incorrect diagnosis have died of the disease. Adenoma malignum is a potentially malignant tumor histologically characterized by adenomatous proliferation with structural abnormality in the shape and arrangement of the gland and budding invasive pattern into the stroma. The gland filled with mucous substance often ballooned and ruptured resulting in the leakage of mucous substance into the surrounding stromal tissue. Light and electron microscopical observation of the epithelial cells revealed that they were quite different from those of conventional adenocarcinoma. Excessive mucus-producing activity and variation in nuclear DNA content can lead to possible differential cytodiagnosis between tumorous and normal columnar cells. The finding of positive CEA in the cytoplasm of the tumor cell obtained in the immunohistochemical study led to further study to detect CEA in the cervical mucus in screening for this rare tumor.

Adenocarcinoma↗