Biomedical subjects

Yo-ichi Yamashita

Publications and source records attributed to Yo-ichi Yamashita.

11 recordsLinked to original sources

PubMed2004

cDNA microarray analysis in hepatocyte differentiation in Huh 7 cells.

The risk of xenozoonosis infections poses the greatest obstacle against the clinical application of a hybrid artificial liver support system (HALSS). Primary human hepatocytes are an ideal source for HALSS, but the shortage of human livers available for hepatocyte isolation limits this modality. To resolve this issue, we previously demonstrated the upregulation of hepatocyte-specific function by spheroid formation in polyurethane foam and by culturing with the histone deacetylase inhibitor, trichostatin A (TSA), in a human hepatoma cell line (Huh 7). In this article we analyze the gene expression profile using cDNA microarray (1281 genes) in spheroid formation or culturing with TSA in Huh 7 to determine the target genes in hepatocyte differentiation. In both the spheroid formation and in the culture with TSA, the Oct-3/4 transcription factor was upregulated more thantwofold, while the early growth response-1 (EGR-1) transactivator was downregulated less than 0.5-fold. These results indicate that expressions of Oct-3/4 and EGR-1 may be key factors in the induction of hepatocyte differentiation in Huh 7.

Cell Culture Techniques↗

PubMed2003

Histone deacetylase inhibitor trichostatin A induces cell-cycle arrest/apoptosis and hepatocyte differentiation in human hepatoma cells.

Remodeling of the chromatin template by inhibition of HDAC activities represents a potential transcriptional therapy for neoplastic disease. A number of HDAC inhibitors that modulate in vitro cell growth and differentiation have been developed. We analyzed the effects of TSA, a specific and potent HDAC inhibitor, on the human hepatoma cell lines HepG2 and Huh-7. TSA increased levels of acetylated histones H3 and H4 in both HepG2 and Huh-7. It inhibited cell proliferation in vitro and induced G(0)/G(1) arrest in HepG2 and apoptosis in Huh-7. Gene expression of liver-specific functions and liver-enriched transcription factors was upregulated by TSA. TSA upregulated the ammonia removal rate and the albumin synthesis rate of HepG2 and Huh-7. Our results indicate that TSA can induce cell-cycle arrest/apoptosis and hepatocyte differentiation in human liver cancer cell lines.

Albumins↗

PubMed2003

Efficacy of a larger version of the hybrid artificial liver support system using a polyurethane foam/spheroid packed-bed module in a warm ischemic liver failure pig model for preclinical experiments.

We have reported the usefulness of a polyurethane foam packed-bed culture system of hepatocyte spheroids as a hybrid artificial liver support system (PUF-HALSS). The aim of this study was to evaluate in detail the efficacy in serum parameters regarding the liver function of a larger version of the PUF-HALSS containing 2 x 10(10) porcine hepatocytes for clinical use in warm ischemic liver failure pigs. Warm ischemic liver failure pigs weighing 25 kg were divided into two groups: (1) a control group (n = 3), in which each pig was attached to a PUF-HALSS without hepatocytes, and (2) a HALSS group (n = 3), in which each pig was attached to a PUF-HALSS. In the HALSS group, the increase of blood ammonia was completely suppressed and blood lactate levels were significantly suppressed. The Fisher's ratio was better maintained, and the increase of total bile acid, glycochenodeoxycholic acid, and taurochenodeoxycholic acid was significantly suppressed in the HALSS group. Serum creatinine levels were significantly lower, and blood glucose levels were significantly higher in the HALSS group. Serum levels of tumor necrosis factor- a were not elevated in either group. In conclusion, the larger version of the PUF-HALSS demonstrated many advantages as a liver support system in warm ischemic liver failure pigs.

Amino Acids↗

PubMed2003

Angiogenic switch as a molecular target of malignant tumors.

In vivo progression to malignancy is characterized by the switch to an angiogenic phenotype. The angiogenic switch is a critical control point for tumor expansion. The ability of a tumor to become neovascularized permits rapid expansion of tumor growth and increases the likelihood of metastases. The genetic alterations that accompany the switch to the angiogenic phenotype are unknown. Discoveries of such genes lead to comprehension of molecular mechanisms of the tumor progression, as well as development of novel therapeutic tools. We have isolated a novel "angiogenic switch molecule," angiopoietin-2, upregulated specifically in hypervascular hepatocellular carcinoma (HCC). Angiopoietin family proteins have been originally identified as ligands of the vascular endothelial receptor of tyrosine kinase Tie2. Ectopic expression of angiopoietin-2 promotes the rapid development of human HCCs and produces hemorrhage within tumors in nude mice. These results suggest a role for angiopoietin-2 in the neovascularization of HCC. In vitro expression of a dominant-negative construct, containing a soluble Tie2 ectodomain (sTie2), led to Angiopoietin protein interaction, inhibition of endogenous Tie2 phosphorylation in vascular endothelial cells. Tumorigenicity with angiogenesis was suppressed by in vivo gene transfer and sTie2 expression in a murine HCC model, suggesting a possible role for angiopoietin/Tie2 signaling in the induction of HCC neovascularization and disease progression. More important, inhibition of the angiopoietin/Tie2 signal transduction cascade is a promising approach for HCC treatment.

Angiogenesis Inducing Agents↗

PubMed2002

In vivo gene transfer into muscle via electro-sonoporation.

Among the nonviral techniques for gene transfer in vivo, electroporation is simple, potent, inexpensive, and safe. To upregulate the expression levels of the transferred gene, we investigated the applicability of in vivo electro-sonoporation, which consists of a combination of electric pulse and ultrasound, for gene transfer using plasmid DNA encoding luciferase and mouse interleukin-12 (mIL-12). The quadriceps muscles of mice were injected with plasmid DNA, then sonoporated for 5 min, and electroporated by a pair of electrode plates at the middle of the duration of sonoporation. Three days later, mice that had undergone electro-sonoporation demonstrated twofold higher luciferase activity and low tissue damage in quadriceps muscle compared to mice having undergone electroporation alone. Serum mIL-12 levels in mice that had undergone electro-sonoporation (peaking at 25.5 ng/ml) were twofold higher after gene transfer than were those in mice having undergone electroporation alone (peaking at 14.3 ng/ml), and maintained high serum level of 13.9 ng/ml at 28 days after gene transfer. The efficacy of gene transfer via electro-sonoporation was superior when the plasmid DNA solution was 0.85% NaCl compared to albumin microbubble echo-contrast material. These results demonstrated that gene transfer into muscle via electro-sonoporation could provide a new potent nonviral technique for gene transfer in vivo.

Animals↗

PubMed2002

Clinicopathologic risk factors for recurrence after a curative hepatic resection for hepatocellular carcinoma.

BACKGROUND: The long-term prognosis after resection for patients with hepatocellular carcinoma is still unsatisfactory because of the high recurrence rate. The survival of patients with multiple intrahepatic or extrahepatic recurrence is especially poor. METHODS: Among the patients who underwent hepatic resection for hepatocellular carcinoma between 1981 and 2000, 216 patients with 3 or less than 3 intrahepatic recurrences (group B); 156 patients with more than 3 intrahepatic recurrences, extrahepatic recurrences, or both (group C); and 51 patients who survived more than 5 years without recurrence (group A) were clinicopathologically studied. RESULTS: The period to recurrence of group C was significantly earlier than that of group B and also showed a significantly poor prognosis after recurrence. Tumor factors, including size, portal venous invasion, intrahepatic metastasis, histologic grade, or the number of tumors at resection in group C was significantly worse than in groups A and B. Although no differences are recognized in the tumor factors between groups A and B, except for the alpha-fetoprotein level, liver function in group B was significantly worse than that in group A. In addition, the frequency of hepatitis B surface antigen in group B and that of hepatitis C virus in group B was significantly less and higher than that in group A, respectively. CONCLUSION: Similar to extrahepatic metastasis, multinodular recurrences are also mainly caused by metastatic recurrence from the main tumor by means of the portal system, and recurrences with up to 3 intrahepatic nodules are mainly caused by metachronous multicentric hepatocarcinogenesis. Because the mechanisms of recurrence differed, determining the patterns of recurrence on the basis of the clinicopathologic findings is important for selecting the optimal postoperative therapy for each individual patient.

Alanine Transaminase↗

PubMed2002

Intrahepatic cholangiocarcinoma: its mode of spreading and therapeutic modalities.

Intrahepatic cholangiocarcinoma (IHCC) is a primary adenocarcinoma of the liver, arising from the intrahepatic bile ducts. The prognosis is generally poor because locoregional extension is usually advanced at the time of diagnosis. Even after a resection, the outcome for patients with advanced IHCC is extremely poor, and the presence of lymph node metastasis has been reported in most previous studies to be the worst prognostic factor after a resection. There are no clear guidelines on lymph node dissection with IHCC. In this article, we review the mode of invasion and the therapeutic modalities: hepatic resection, lymph node dissection, liver transplantation, radiation, and chemotherapy for IHCC.

Adenocarcinoma↗

PubMed2002

Minimally invasive hepatectomy: modulation of systemic reactions to operation or laparoscopic approach?

BACKGROUND: A new concept of surgical stress has been proposed that consists of both aggressiveness of operation and systemic reactions to an operation. METHODS AND RESULTS: We have investigated a possible modulation of such systemic reactions to operation and have demonstrated the following 3 points: (1) coagulation and fibrinolytic systems are independently activated during hepatectomy and such activation can be modulated by protease inhibitors such as nafamostat mesilate and antithrombin III; (2) elevated thromboxane A2 during hepatectomy is characterized in the prostanoid system, the elevation of thromboxane A2 is inhibited by thromboxane A2 synthetase inhibitor, and postoperative liver injury is reduced; (3) cytokine response induced by hepatectomy is modulated by preoperative administration of methylprednisolone, leading to possible prevention of bacterial translocation. Therefore, modulating systemic reactions to hepatectomy may be important for successful minimally invasive hepatectomy. Another important option for minimally invasive hepatectomy is the use of operative procedures such as laparoscope or thoracoscope. We have investigated the usefulness of a laparoscopic hepatectomy from the standpoints of early and long-term outcome after hepatectomy. Laparoscopic hepatectomy, which is a difficult and dangerous procedure, can be a feasible option and can result in better short-term outcome and a similar long-term outcome after hepatectomy when compared with conventional open hepatectomy. Therefore, the laparoscopic approach is also a viable option for minimally invasive hepatectomy. CONCLUSIONS: Modulation of systemic reactions to the operation itself and laparoscopic hepatectomy may be new strategies for performing minimally invasive hepatectomy.

Blood Coagulation↗

PubMed2002

Hybrid-artificial liver support system.

We originally developed a multi-capillary polyurethane foam packed-bed module as a hybrid-artificial liver support system (HALSS) and have applied for the permission of the clinical application to our institutional ethical committee. We summarized here the history, recent obstacles in clinical applications, and future prospects of HALSS, including our own.

Animals↗

PubMed2002

High metabolic function of primary human and porcine hepatocytes in a polyurethane foam/spheroid culture system in plasma from patients with fulminant hepatic failure.

It has been demonstrated that plasma from patients with fulminant hepatic failure (FHF) interferes extensively with cellular function. We placed primary human and primary porcine hepatocytes in a polyurethane foam (PUF)/spheroid culture system and compared the metabolic functions in the plasma of patients with FHF in a 24-h stationary culture to those in a monolayer culture. The PUF/spheroid culture system using primary human and primary porcine hepatocytes significantly decreased ammonia content during 28-day culture. Fisher's ratio significantly increased at culture days 3 and 7. Tauroursodeoxycholic acid significantly increased and glycochenodeoxycholic acid and taurochenodeoxycholic acid decreased in the FHF patients' plasma at culture day 3. During at least a 24-h culture in the FHF patients' plasma, metabolic functions of primary human and primary porcine hepatocytes were almost identical. The present results indicate that the PUF/spheroid culture system using primary human or primary porcine hepatocytes demonstrated more advantageous metabolic functions in the plasma from patients with FHF than the monolayer culture.

Ammonia↗

PubMedDate not supplied

Gemcitabine combined with 5-fluorouracil and cisplatin (GFP) in patients with advanced biliary tree cancers: a pilot study.

BACKGROUND: Advanced biliary tree cancers have poor prognosis and chemotherapy has been shown to have little impact. To date, no standard chemotherapy regimens have been established. A pilot study to evaluate gemcitabine/5-Fluorouracil(5-FU)/cisplatin(CDDP) (GFP) chemotherapy in patients with advanced biliary tree cancers was performed. PATIENTS AND METHODS: Eight patients with advanced intrahepatic cholangiocarcinoma and gallbladder carcinoma with no prior chemotherapy were treated with a 4-week cycle GFP chemotherapy consisting of gemcitabine at 1000 mg/m2 on days 1, 8, and 15, and of 5-FU at 250 mg/patient and CDDP at 5 mg/patient on days 1 to 5, 8 to 12 and 22 to 26. RESULTS: Of these 8 patients, no complete responses (CR) were observed, but 3 patients (37.5%) demonstrated partial responses (PR) with an additional 3 patients (37.5%) having stable diseases (SD), as assessed by RECIST. Two patients with PR and 1 patient with SD were treated by curative operation after GFP chemotherapy and all of them survived with no recurrence. The median overall survival time was 23.5 months, and median time to progression was 14.5 months. Grade 3/4 side-effects, such as leukopenia, thrombocytepenia and anemia were found in 4 patients (50%), but no patients dropped out because of toxicity. CONCLUSION: This GFP chemotherapy has promising antitumor activity and is well tolerated in patients with advanced biliary tree cancers. This regimen warrants further evaluation in a phase II study including larger numbers of patients.

Adenocarcinoma↗