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T Yoshikawa

Publications and source records attributed to T Yoshikawa.

At least 307 records · Page 17Linked to original sources
PubMed1999

A novel water-soluble vitamin E derivative protects against experimental colitis in rats.

This study was designed to investigate the effects of water-soluble vitamin E derivative, 2-(alpha-D-glucopyranosyl)methyl-2,5,7,8-tetramethylchroman-6-ol (TMG), on experimental colitis in rats. Colitis was induced in male Wistar rats weighing 200 grams using an enema of trinitrobenzene sulfonic acid (TNBS) dissolved in 50% ethanol; 1 ml of TMG dissolved in physiological saline (0.2 mg/ml, 2 mg/ml, 20 mg/ml) was injected intraperitoneally every day for 1 week after the enema. The damage score, wet weight of the colon, and increase in body weight were estimated 1 week after the enema of TNBS. Thiobarbituric acid-reactive substances (TBA-RS), an index of lipid peroxidation, and the level of alpha-tocopherol or TMG in the colonic mucosa were measured 1 week after the induction of colitis. As a result, increase in body weight was inhibited by the induction of colitis, although the inhibition was reduced in the group treated with TMG. The damage score, wet weight and TBA-RS were increased significantly in the colitis group; however, they were inhibited by the administration of TMG. The alpha-tocopherol level in the colonic mucosa was reduced by the induction of colitis, wheres TMG could not be detected in the colonic mucosa of rats treated with TMG. These results suggest that TMG is effective for the treatment of colitis in rats induced by TNBS.

Animals↗
PubMed1999

Lymph node metastasis in intrahepatic cholangiocarcinoma.

BACKGROUND: Lymph node metastasis is a significant prognostic factor in intrahepatic cholangiocarcinoma. This study was aimed at investigating lymph node metastasis in intrahepatic cholangiocarcinoma and to examine whether the extent of metastasis affects outcomes after surgery. METHODS: From 1980 through 1996, 70 patients with intrahepatic cholangiocarcinoma underwent hepatectomy, with a 50% curative resection rate. Lymph node dissection was performed in 51 patients, and the presence of lymph node metastasis was examined microscopically. The metastatic nodes were divided into groups N1, N2 or N3 using the classification proposed by the Liver Cancer Study Group of Japan. RESULTS: Twenty-three patients had lymph node metastasis. Metastasis was to N1 nodes in 10 patients, to N2 nodes in nine patients and to N3 nodes in four patients. Nineteen patients had metastatic nodes in the hepatoduodenal ligament, which was the most common metastatic site regardless of tumor location. The five-year survival rate in patients with lymph node metastasis (0%) was significantly lower (p < 0.0001) than that in patients without lymph node metastasis (51 %); however, five-year survival rates did not differ between patients with metastases to N1, N2 and N3 nodes. CONCLUSIONS: Lymph nodes in the hepatoduodenal ligament may be sentinel nodes for intrahepatic cholangiocarcinoma, and outcomes after surgery for patients with lymph node metastasis are poor regardless of the sites of nodal metastasis.

Adult↗
PubMed1999

Growth inhibition of A549 human lung adenocarcinoma cells by L-canavanine is associated with p21/WAF1 induction.

L-Canavanine (CAV) is a higher plant nonprotein amino acid and a potent L-arginine antimetabolite. CAV can inhibit the proliferation of tumor cells in vitro and in vivo, but little is known regarding the molecular mechanisms mediating these effects. We demonstrated that the treatment of human lung adenocarcinoma A549 cells with CAV caused growth inhibition; G1 phase arrest is accompanied by accumulation of an incompletely phosphorylated form of the retinoblastoma protein, whose phosphorylation is necessary for cell cycle progression from G1 to S phase. In addition, CAV induces the expression of p53 and subsequent expression of a cyclin-dependent kinase inhibitor, p21/WAF1. The p53-dependent induction of p21/WAF1 and the following dephosphorylation of the retinoblastoma protein by CAV could account for the observed CAV-mediated G1 phase arrest.

Adenocarcinoma↗
PubMed1999

Human herpesvirus 6 latently infects mononuclear cells but not liver tissue.

AIM: To investigate whether human herpesvirus 6 (HHV-6) can cause latent infection of liver tissue. METHODS: Peripheral blood and liver tissue were collected from 25 living related liver transplant recipients at the time of transplantation. An avidin-biotin complex peroxidase method was used to identify HHV-6 antigen in the liver tissue. A nested polymerase chain reaction (PCR) was used to detect HHV-6 DNA in the liver tissue and mononuclear cells. Variant of HHV-6 was determined by the presence of the Hind III site in a second PCR product. RESULTS: Immunohistochemical analysis for HHV-6 antigen was negative in all the liver specimens. HHV-6 DNA was not detected in liver tissue. Virus DNA was detected in peripheral blood mononuclear cells in nine of 25 recipients. All nine HHV-6 identified in the mononuclear cells were variant B. CONCLUSIONS: HHV-6 variant B latently infects mononuclear cells but not liver tissue.

Adolescent↗
PubMed1999

Calcification in untreated non-Hodgkin's lymphoma of the jejunum.

A 69-year-old Japanese female was admitted to our hospital due to a 2-month history of vomiting after eating. Examination of the small intestinal tract revealed a tumor with calcification in the inner portion, from the horizontal portion to the ascending portion of the duodenum, and jejunojejunostomy was performed. The pathological findings of the tumor gave a diagnosis of non-Hodgkin's lymphoma, diffuse small cleaved cell (Working Formulation classification), B cell type, of the jejunum. Calcification is rarely found in untreated malignant lymphoma and 15 cases of untreated malignant lymphoma with calcification have been reviewed.

Adolescent↗
PubMed1999

Effects of dentin depth and cavity configuration on bond strength.

During polymerization of resin composites, shrinkage stresses compete with resin-dentin bonds in a manner that can cause failure of the bond, depending upon the configuration of the cavity, its depth, and the restorative technique. The hypothesis tested in this study was that the effect of cavity configuration (C) and remaining dentin thickness (RDT) influence resin bond strength to the dentin of Class I cavity floors. The occlusal enamel was ground to expose a flat superficial dentin surface as a control (superficial dentin, C-factor = 1) in human extracted third molars. Cavities 3 mm long x 4 mm wide were prepared to a depth 2 mm below the ground dentin surfaces (deep dentin within cavity floor, C-factor = 3). To assess the relationship between C-factor and RDT, we removed the walls of cavities, making a deep flat surface for bonding (deep dentin, C-factor = 1). The teeth were restored with either Clearfil Liner Bond II (LB II), One-Step (OS), or Super-Bond D Liner (DL), followed by Clearfil Photo Posterior resin composite. After 24 hrs' storage in water, the teeth were sectioned vertically into 3 or 4 slabs (0.7 mm thick) and trimmed for the micro-tensile bond test so that we could determine the strength of the resin bonds to the pulpal floor. All groups gave high bond strengths to superficial dentin, but OS and DL gave significantly lower bond strengths to flat deep dentin when the C-factor was 1. When the C-factor was increased to 3 by the creation of a three-dimensional cavity preparation, the bond strengths of all materials fell (range, 21 to 35%), but the difference was significant (p < 0.05) only with DL. SEM observations of failure patterns showed that specimens with high bond strengths tended to exhibit cohesive failures within the hybrid layer, while specimens exhibiting low bond strengths showed failures at the top of the hybrid layer. Some adhesives do not bond well to deep dentin, making them more susceptible to polymerization shrinkage stress that develops in cavities with high C-factors.

Analysis of Variance↗
PubMed1999

Long-term durability of dentin bonds made with a self-etching primer, in vivo.

The long-term durability of bonds between adhesive resins and dentin is of significant importance for the longevity of bonded restorations. We carried out an in vivo one-year study to evaluate the durability of resin-dentin bonds in the oral cavity, as well as to test the hypothesis that the adhesive interface would show morphological changes in vivo over time. Very shallow saucer-shaped dentin cavities were prepared in 12 intact teeth of one Japanese monkey (Macaca fuscata) under general anesthesia. The cavities were restored with Clearfil Liner Bond II and Clearfil Photo Posterior resin composite. The teeth were extracted at three different times: immediately, and 180 and 360 days after placement of the restorations. One day after the monkey was killed, specimens of the three time periods were subjected to the micro-tensile bond test at a crosshead speed of 1 mm/min. The surfaces of the failed bonds were observed under a field emission scanning electron microscope (FE-SEM). Bond strength measurements in this study were successfully performed and were stable at approximately 19 MPa during the one-year testing. Scanning electron microscopic observations of the failed surfaces revealed, at the top of the hybrid layer and within the adhesive resin, porosity which increased over time. Long-term bonds can be assessed in vivo by the combined evaluation of the microtensile bond strength and SEM morphological examination of the adhesive interface.

Acid Etching, Dental↗
PubMed1999

Regioselective conjugation of chitosan with a laminin-related peptide, Tyr-Ile-Gly-Ser-Arg, and evaluation of its inhibitory effect on experimental cancer metastasis.

A conjugate from the YIGSR peptide and chitosan has been prepared on the basis of a regioselective modification strategy of chitosan, and its antimetastatic activity has been assayed. Chitosan was converted to its organosoluble derivative, 6-O-trityl-chitosan, in 3 steps, and then coupled with the peptide portion containing a spacer amino acid, Ac-Tyr-Ile-Gly-Ser-Arg-beta Ala-OH [beta Ala; beta-alanine]. The product was treated with CHCl2CO2H to afford the desired conjugate, Ac-Tyr-Ile-Gly-Ser-Arg-beta Ala-chitosan, which proved to inhibit the experimental lung metastasis of B16BL6 melanoma cells in mice at lower doses than the parent peptide.

Animals↗
PubMed1999

Generation of reactive oxygen species and 8-hydroxy-2'-deoxyguanosine formation from diesel exhaust particle components in L1210 cells.

The generation of the reactive oxygen species during the interaction of diesel exhaust particles (DEP) with NADPH-cytochrome P450 reductase (P450 reductase) was investigated by electron spin resonance using the spin-trap 5,5'-dimethyl-1-pyrroline-N-oxide (DMPO). Addition of DEP extract to an incubation mixture of mouse lung microsomes in the presence of NADPH resulted in a time-dependent NADPH oxidation and acetylated-cytochrome c reduction. Using purified P450 reductase as the enzyme source, superoxide radicals which were detected as the spin adduct (DMPO-OOH) while metabolized by P450 reductase were dependent upon both DEP and enzyme concentrations. The ELISA method using a specific monoclonal antibody revealed that DEP produced 8-hydroxy-2'-deoxyguanosine (8-OHdG), which is formed from deoxyguanosine in DNA by hydroxyl radicals, in the culture medium of L1210 cells. Active oxygen scavengers such as superoxide dismutase and catalase effectively blocked the formation of 8-OHdG in culture medium, and deferoxamine, which inhibits hydroxyl radicals production by chelating iron, was also effective in inhibiting the DEP-produced 8-OHdG formation. These results indicate that DEP components produce 8-OHdG through the hydroxyl radical formation via superoxide by redox cycling of P450 reductase.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1999

Osteogenic phenotype expression of allogeneic rat marrow cells in porous hydroxyapatite ceramics.

Porous hydroxyapatite (HA) ceramics were combined with either allogeneic (ACI) or isogeneic (Fischer 344) rat marrow cells and implanted in subcutaneous sites of Fischer rats. FK506 as an immunosuppressant or saline was administered to the recipient rats. The implanted marrow/HA composites were harvested on day 28 and analyzed for bone-forming capability by determining osteoblastic phenotype expression levels of protein synthesis and gene expression. The alkaline phosphatase (ALP) activity and osteocalcin (OC) contents were very low and mRNAs (Northern blot analysis) were not detected in the allografts without FK506. However, high activity of ALP and high content of OC were found and mRNAs were detected in the allografts with FK506 and in the isografts (with and without FK506). This analysis indicates the osteogenic potential of allogeneic marrow cells in the presence of FK506. The histologic sections revealed that allografts without FK506 did not show bone formation but did show the infiltration of many small cells in the ceramics indicating an immunologic reaction, however, the allografts with FK506 and the isografts (with and without FK506) showed consistent de novo bone formation on the HA pore surface. These results indicate that FK506 can suppress the immunologic reaction in the allografts and induce a favorable conditions to support osteoblastic differentiation of allogeneic rat marrow stromal stem cells on the surface of HA ceramics. Therefore, our study suggests the feasibility of clinical transplantation of allogeneic bone marrow for a selected bone graft in applications using adjuvant systemic immunosuppression.

Alkaline Phosphatase↗
PubMed1999

Spread of varicella-zoster virus DNA to family members and environments from siblings with varicella in a household.

OBJECTIVE: To elucidate virus spread from siblings with varicella to other family members and environmental objects in a family setting before and after onset of the disease. MATERIALS AND METHODS: Among a family consisting of five members, a boy developed varicella and the remaining two siblings developed the disease 17 and 18 days after onset of the index case. Swab samples from throats and hands of parents and three siblings and samples from several sources in the environment of the house were collected frequently before and/or after onset of the disease. Varicella-zoster virus (VZV) DNA in the samples was examined by a sensitive polymerase chain reaction amplification assay. RESULTS: In total, 108 samples from the throats and hands of the three children with varicella, 72 such samples from parents, and 72 samples from the surfaces of several sources in the house were collected. Eight days after onset of the index case (the older boy), VZV DNA was detected in both samples from the index case and on the surfaces of four sources (air conditioner filter, table, television channel push-buttons, and door handle), but not from the two other siblings or parents. Then, it was detected once on the mother's hand and the air conditioner filter and three times on the television channel push-buttons by January 30, 1998, when the girl developed varicella, 17 days after onset of the index case. The younger brother developed the disease on January 31. Viral DNA could not be detected in any samples obtained on January 30; however, it was detected on the hands of the older boy and the father and in samples from the hand and throat of the girl on January 31. Thereafter, virus DNA was detected three times intermittently by February 13 on the hand and three times persistently in the throat of the girl. The virus DNA was detected three times between February 1 and 3 on the hand and three times between February 1 and 4 in the throat of the younger boy. It was detected occasionally on the hands of the older boy and the parents, and occasionally or intermittently on surfaces of four environmental sources between February 2 and 13. CONCLUSIONS: The present study showed the rapid and broad contamination of the environment with the VZV DNA when the varicella patient appeared in a family, although it does not directly mean infectivity.

Adult↗
PubMed1999

Transesophageal echocardiographic detection of cardiac sources of embolism in elderly patients with ischemic stroke.

OBJECTIVE: The aim of this study was to clarify the role of transesophageal echocardiography in detecting cardiac sources of embolism in elderly stroke patients. METHODS: We performed transesophageal echocardiography in 77 patients > or = 70 years old (mean 76.9) with ischemic stroke and investigated embolic sources. Thirty-seven patients were in sinus rhythm (SR) and 40 in atrial fibrillation (Af). RESULTS: Left atrial spontaneous echo contrast was detected in 73% of Af and in 14% of SR (p<0.01). Left atrial thrombus was present in 10% of Af and none of SR (p<0.05). Patent foramen ovale, atrial septal aneurysm, and aortic atherosclerotic plaque > or = 4.0 mm in thickness in the proximal aortic arch were more commonly found in patients with SR. CONCLUSIONS: In elderly ischemic stroke patients, 1) Left atrial spontaneous echo contrast and thrombus are more commonly detected in patients with Af, reflecting left atrial enlargement and blood stasis, and 2) atrial septal aneurysm, patent foramen ovale and aortic atherosclerotic plaque > or = 4.0 mm in thickness in the proximal aortic arch are important findings in patients with SR.

Aged↗
PubMed1999

Pancreatic phospholipase A2 induces bacterial translocation in rats.

The importance of pancreatic enzymes, particularly phospholipase A2 (PLA2), for bacterial translocation, which is considered to be one of the aggravating causes of acute pancreatitis, was investigated. Male rats were administered an intraperitoneal or intravenous injection of normal saline, PLA2, or amylase. Four days later, the mesenteric lymph nodes (MLNs) and portal blood of the animals were cultured. None of the animals had a positive portal blood culture. The MLNs contained enteric bacteria in 78% of the animals given 50 mg/kg of PLA2 intraperitoneally. 5 mg/kg of PLA2 intraperitoneally, 50 mg/kg of amylase intraperitoneally, or 50 mg/kg of PLA2 intravenously showed positive cultures in 25%, 20%, and 11%, respectively. None of the animals given intraperitoneal or intravenous normal saline had positive cultures of their MLNs. Intraperitoneal injection of 25 mg/kg of nafamostat mesilate just before intraperitoneal PLA2 (50 mg/kg) resulted in a reduction of positive MLNs from 70% to 30%. The cecal myeroperoxidase (MPO) activity of animals administered 50 mg/kg of PLA2 intraperitoneally was significantly higher compared with animals administered saline intraperitoneally. These results indicate that intraperitoneal leakage of PLA2 plays an important role in bacterial translocation during acute pancreatitis and that administration of a protease inhibitor may be effective against the bacterial translocation.

Acute Disease↗
PubMed1999

[Evaluation of two-dimensional thick-slice MR DSA: preliminary study].

We have used two-dimensional contrast-enhanced MR angiography for a single thick slice and called it MR DSA. This technique realizes nearly subsecond scanning per image and is therefore superior to other types of contrast-enhanced MR angiography in temporal resolution. To determine the optimal parameters of this technique, we calculated SSR (the signal of brain to the signal of contrast agent ratio) in various settings. We also obtained MR DSA images of 26 cases. We believe that MR DSA may play a supportive role in conventional MR imaging or angiography, since its high temporal resolution is of value in the evaluation of cerebrovascular diseases.

Angiography, Digital Subtraction↗
PubMed1999

[A case report of esophageal small cell carcinoma responding well to chemotherapy of 5-FU and cisplatin combined with radiotherapy].

A seventy-eight year-old man with esophageal small cell carcinoma was reported. He was treated with chemotherapy of 5-FU and Cisplatin combined with radiotherapy. After 3 Courses of chemotherapy, the tumor almost disappeared. A biopsy specimen revealed moderate dysplasia but did not show residue of small cell carcinoma. The patient had lived with no evidence of cancer recurrence for 1.5 years. He died of lung metastasis and pleuritis carcinomatosa about two years after the first treatment with chemotherapy. Chemotherapy of 5-FU and Cisplatin (combined with radiotherapy) is one of the useful treatments for patients with small cell carcinoma of the esophagus.

Aged↗
PubMed1999

Osteogenic differentiation of cultured marrow stromal stem cells on surface of microporous hydroxyapatite based mica composite and macroporous synthetic hydroxyapatite.

In order to investigate the significance of hydroxyapatite based microporous composite (HA/mica composite) surfaces and a macroporous synthetic hydroxyapatite, rat marrow cell culture, which shows osteogenic differentiation, was carried out on six different culture substrata (two control culture dishes, two identical HA/mica composites, and two identical macroporous synthetic hydroxyapatites). A culture period of two weeks in the presence of beta-glycerophosphate (BGP), ascorbic acid, and dexamethasone resulted in abundant mineralized nodule formations that were positive for alkaline phosphatase (ALP) stain. The stain on the macroporous synthetic hydroxyapatite and the HA/mica composites were intense, the enzyme activity being about double that of control culture dishes. These data indicate that the synthetic macroporous hydroxyapatite surface and the HA/mica composite surface promotes osteoblastic differentiation.

Alkaline Phosphatase↗
PubMed1999

Effect of a new inhibitor of type II phospholipase A2 on experimental acute pancreatitis in rats.

The catalytic activity of type II phospholipase A2 (PLA2) in blood has been reported to increase in acute pancreatitis and to reflect the severity of pancreatitis. In this study, we evaluated the effects of a new inhibitor of type II PLA2, S5920/LY315920Na, on trypsin-taurocholate-induced pancreatitis in rats. Hemorrhagic pancreatitis was induced by an infusion of a mixture of trypsin and taurocholate into the pancreatic duct. S5920/LY315920Na was administered subcutaneously at 0 h and 3 h after the induction of pancreatitis. Survival rates for 24 h in rats treated with 0.1 and 1 mg/kg of S5920/LY315920Na were significantly higher than that in untreated rats (71 and 86% vs. 14%). Serum levels of amylase and lipase in rats treated with 1 mg/kg of S5920/LY315920Na were significantly lower than those in untreated rats (amylase, 6,903 vs. 32,516 U/L; and lipase, 514 vs. 6,710 U/L) at the time of death or 24 h after the induction of pancreatitis. Plasma levels of S5920/LY315920Na were enough to inhibit catalytic activity of PLA2 in plasma for 9 h. A new inhibitor of type II PLA2, S5920/LY315920Na, inhibited catalytic activity of PLA2 and improved the survival rate in experimental hemorrhagic pancreatitis in rats.

Acetates↗