In vivo stimulation on rabbit retina using CMOS LSI-based multi-chip flexible stimulator for retinal prosthesis.

We have performed in vivo electric stimulation experiments on rabbit retina to demonstrate feasibility of CMOS LSI-based multi-chip flexible neural stimulator for retinal prosthesis. We have developed new packaging structure with an improved flexibility and device control system which totally controls the LSI-based multi-chip stimulator, counter electrode, and stimulation generator. We have implanted the fabricated multi-chip stimulator into sclera pocket for STS (Suprachoroidal Transretinal Stimulation) configuration. We successfully obtained EEP (Electrically Evoked Potential) on visual cortex evoked by the multi-chip stimulator.

Laboratory investigation of microelectronics-based stimulators for large-scale suprachoroidal transretinal stimulation (STS).

This paper describes the technological developments underlying the realization of a reliable and reproducible microchip-based stimulator with a large number of stimulus electrodes. A microchip-based stimulator with over 500 electrodes for suprachoroidal transretinal stimulation (STS) is proposed in this paper, and an example is presented. To enhance reliability and reproducibility for such a large array, we introduce a flip-chip bonding technique and place microchips on the reverse side of a substrate. A square microchip of size 600 microm was fabricated using 0.35 microm standard CMOS process technology. Twelve microchips were flip-chip bonded on a polyimide substrate through Au bumps. To evaluate the feasibility of the proposed device, we successfully fabricated a stimulator with 12 microchips and 118 electrodes made of Pt/Au bumps, and demonstrated their operation in a saline solution for 2 weeks. Also, to evaluate the device operation in vivo, a stimulator with one active IrO(x) electrode was implanted into the scleral pocket of a rabbit and electrical evoked potential (EEP) signals with a threshold of 100 microA were obtained. We also fabricated a simulator with 64 microchips that has 576 electrodes (9 electrodes in a microchip times 64 microchips).

A multi-chip-architecture based flexible stimulation device for retinal prosthesis with a flip-chip packaging technique.

In the present work, we designed a multi-chip-architecture based flexible neural stimulation device for retinal prosthesis. Based on the multi-chip architecture, a novel CMOS stimulation device was successfully designed and characterized. A packaging technique for thin, flexible neural stimulation device was also proposed and demonstrated. Flip-chip bonding technology plays an essential role in the fabrication of the present thin and flexible neural stimulation device.

Improved survival with oral administration of enteric-coated tegafur/uracil for advanced stage IV-A hepatocellular carcinoma.

BACKGROUND AND AIMS: There is currently no proven chemotherapy regimen for hepatocellular carcinoma (HCC). The principal chemotherapeutic approach in most cases is infusion therapy into the hepatic arteries feeding the tumors. However, the clinical effects of chemotherapy are extremely poor. Therefore, in the present study, we conducted a prospective randomized trial of the efficacy of oral administration of enteric-coated tegafur/uracil for advanced HCC. METHODS: From 1994 to 1999, a total of 56 consecutive patients with unresectable stage IV-A HCC were studied prospectively to examine the efficacy of enteric-coated tegafur/uracil in HCC and to determine the significant prognostic factors. Twenty-eight patients were treated only with enteric-coated tegafur/uracil without other anticancer treatment. Another 20 patients were given conservative management only. The remaining eight patients withdrew from the study. RESULTS: In the group treated only with enteric-coated tegafur/uracil, the median survival time and 1 and 2 year survival rates were 12.13 months and 55.3 and 36.9%, respectively. In the control group, the median survival time and 1 year survival rate were 6.20 months and 5.5%, respectively. By both univariate analysis and multivariate analysis using Cox's proportional hazards model, treatment with enteric-coated tegafur/uracil was shown to be the factor most significantly favoring a better prognosis. CONCLUSIONS: Although the prognosis of most patients with stage IV-A HCC is poor, administration of enteric-coated tegafur/uracil induces long-term survival and is an effective treatment for stage IV-A HCC.

Clinical features and etiology of hepatocellular carcinoma arising in patients with membranous obstruction of the inferior vena cava: in reference to hepatitis viral infection.

BACKGROUND AND AIMS: Budd-Chiari syndrome (BCS) comprises hepatic vein thrombosis and inferior vena cava (IVC) obstruction known as membranous obstruction of the IVC (MOVC). The latter is frequently complicated by hepatocellular carcinoma (HCC). The etiology of MOVC-associated HCC in relation to hepatitis viral infection is not known. In this study, we investigated the clinical features and etiology of HCC in MOVC. METHODS: Membranous obstruction of IVC and HCC were diagnosed and studied by using imaging techniques. Sera from patients with MOVC, complicated by HCC, were examined for hepatitis viral antigens and antibodies (hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs), antibody to hepatitis B core antigen (anti-HBc) and third generation antibody to hepatitis C virus (anti-HCV)) and for hepatitis viral nucleic acids (hepatitis B virus (HBV)-DNA, hepatitis C virus (HCV)-RNA, hepatitis G virus (HGV)-RNA and TT virus DNA). RESULTS: We studied 12 patients with BCS who were seen between April 1968 and February 1999. All of them had MOVC. Hepatocellular carcinoma developed in three (25%) of them. There were no obvious differences in the clinical features and imaging findings concerning MOVC between patients with and without HCC. Hepatocellular carcinoma in these three patients showed no clear trend in clinical features and imaging findings. Of the hepatitis viral markers examined, HBsAg, anti-HBc and HBV-DNA were positive in only one of three patients with HCC and all of the viral markers were negative in the other two patients. CONCLUSIONS: Chronic congestion in the liver, caused by an outflow block of hepatic veins and subsequent histopathologic change, must have led to HCC in two patients without any hepatitis viral markers. Patients with MOVC should be followed closely as a high-risk group for HCC.

Expression of hepatic thrombopoietin mRNA in primary cultured hepatocytes and in rats with acute liver injury or bone marrow suppression with or without cirrhosis.

BACKGROUND AND AIMS: The main causes of thrombocytopenia in cirrhosis are thought to be platelet destruction and the reduction of thrombopoietin (TPO) expression in the liver. The mechanisms by which levels of TPO mRNA are regulated in cirrhosis have not been elucidated. In this study, we investigated some possible mechanisms. METHODS: We used three experimental models: bone marrow suppression, acute liver injury and primary cultured hepatocytes. We used northern blots to assess the kinetics of TPO mRNA expression in the livers of irradiated rats (with and without cirrhosis) in acute liver injury and in primary cultured hepatocytes treated with hepatotoxin or cytokines. RESULTS: Although the bone marrow was hypocellular, there was no apparent enhancement of TPO mRNA expression in the irradiated rats with cirrhotic livers compared with the unirradiated rats with cirrhotic livers. There were no conspicuous changes in hepatic TPO mRNA expression between the livers of the control rats and the three models of acute liver injury. There were no conspicuous changes in the levels of TPO mRNA between control hepatocytes and hepatocytes treated with hepatotoxin or cytokines. CONCLUSIONS: Our results suggest that bone marrow is not a regulator of hepatic TPO production in cirrhosis. The reduced TPO mRNA expression found in cirrhotic rats may not result merely from serious cellular damage; it may be associated with cirrhosis-specific regulatory mechanisms for the expression of the TPO gene. Further studies are needed to search for other factors that may induce reduced TPO expression.

Reduced expression of thrombopoietin is involved in thrombocytopenia in human and rat liver cirrhosis.

It is widely accepted that thrombocytopenia associated with liver cirrhosis is caused by increased platelet destruction in the enlarged spleen, but this issue has not yet been analysed sufficiently in terms of platelet production. Thrombopoietin is produced mainly in the liver and strongly promotes platelet production. We studied serum thrombopoietin and the levels of its mRNA in liver tissue of cirrhotic patients and also in a rat model of liver cirrhosis. Furthermore, to clarify the influence of the spleen, we investigated thrombopoietin mRNA in splenectomized rats. The serum thrombopoietin level in humans with liver cirrhosis was not significantly reduced instead of thrombocytopenia. The expression of thrombopoietin mRNA in liver tissue decreased with the progression of liver cirrhosis in both patients and the rat model and no compensatory expression was observed in other organs or non-parenchymal cells. The level of thrombopoietin mRNA did not differ significantly in splenectomized cirrhotic rats before or after administration of dimethylnitrosamine, but was lower than that in splenectomized rats without cirrhosis. We conclude that thrombocytopenia in liver cirrhosis is caused not only by platelet destruction but also by decreased platelet production, perhaps due to reduction of thrombopoietin mRNA in the liver.

Hyperplastic foci reflect the risk of multicentric development of human hepatocellular carcinoma.

BACKGROUND/AIMS: Identification of the risk factors of multicentric hepatocarcinogenesis is important for the clinical management of hepatocellular carcinoma. We investigated hyperplastic foci in non-cancerous liver parenchyma, and clarified their pathological features and clinical significance. METHODS: Hyperplastic foci were defined as hypercellular areas, which architecturally and cytologically resembled early hepatocellular carcinoma or adenomatous hyperplasia but did not form macroscopically detectable nodules. Surgically resected livers from 155 patients with hepatocellular carcinoma were examined histopathologically and immunohistochemically. RESULTS: Hyperplastic foci were found in 26 of 155 patients (16.8%). All the patients with hyperplastic foci had chronic liver diseases, and the incidence did not differ between those with chronic hepatitis and those with liver cirrhosis. Six of 92 (6.5%) patients with single primary hepatocellular carcinoma nodules, 8 of 42 (19.0%) with two nodules, and 12 of 21 (57.0%) with more than three nodules had hyperplastic foci. The incidence of hyperplastic foci showed a significant positive correlation with the multiplicity of hepatocellular carcinoma nodules. Immunohistochemically, hyperplastic foci were masses of proliferative hepatocytes similar to adenomatous hyperplasia and early hepatocellular carcinoma. CONCLUSIONS: Hyperplastic foci reflect the risk of multicentric hepatocarcinogenesis. Our results suggest strongly that hyperplastic foci are precursors of adenomatous hyperplasia or hepatocellular carcinoma.

Localization of hyaluronan in human liver sinusoids: a histochemical study using hyaluronan-binding protein.

Circulating hyaluronan is mostly derived from lymph, fibroblast and Ito cells in the liver, and more than 90% of hyaluronan is degraded in hepatic sinusoidal endothelial cells. Thus, elevated serum hyaluronan is regarded as an indication of hepatic fibrosis with activated Ito cells and dysfunctional sinusoidal endothelial cells. We studied the distribution of hyaluronan in human liver sinusoids to determine the influences on elevated hyaluronan levels in sera. Histochemical examination was made using hyaluronan-binding protein (HABP) and serial sections of liver tissue for staining of alpha-smooth muscle actin (ASMA) (an indicator of activated Ito cells) and of ulex europaeus agglutinin I lectin (UEA-1) (closely related to hepatic sinusoidal capillarization). Positive staining, indicating the presence of hyaluronan, was noted in fibrous regions around the portal tracts, areas of focal necrosis in the liver parenchyma, and walls of the sinusoids in chronic hepatitis. In this group, hyaluronan-positive areas corresponded to positive ASMA staining and faint staining of UEA-1. On the contrary, in liver cirrhosis, UEA-1-positive areas were essentially identical to hyaluronan-positive areas and to ASMA-negative areas in sinusoidal walls. Hyaluronan and ASMA could be detected in the same areas of sinusoidal walls in chronic hepatitis, but not in liver cirrhosis. Hyaluronan appears to be mainly related to the staining of activated Ito cells in chronic hepatitis. Therefore, we concluded that in chronic hepatitis, the production of hyaluronan was accelerated in Ito cells; however, degradation of hyaluronan by sinusoidal endothelial cells continued. On the contrary, in liver cirrhosis, hyaluronan production decreased in Ito cells, and a marked transformation of sinusoidal endothelial cells with hepatic sinusoidal capillarization indicated loss of the ability to degrade hyaluronan. These different mechanisms in chronic hepatitis and liver cirrhosis may operate in the sinusoidal walls and may cause the elevation of hyaluronan in sera.

Non-secretory alpha chain disease involving stomach, small intestine and colon.

A case of alpha chain disease, involving stomach, small and large intestine, and caecum with poor prognosis is reported. Endoscopic examination revealed gastric erosion, edematous mucosa with enlarged villi of duodenum and jejunum, multiple hyperplastic lymph follicles of terminal ileum and thickening mucosa of caecum. Light microscopy revealed a conspicuous infiltration of plasma cells and lymphocytes in gastric, duodenal, jejunal and caecal lamina propria. Immunohistochemistry demonstrated alpha heavy chain protein devoid of light chain in these plasma cells. The patient developed paralytic ileus and died of septic shock on the 179th hospital day.

Therapeutic effect of a CDDP-epirubicin-Lipiodol emulsion on advanced hepatocellular carcinoma.

Prior injection of an anticancer agent and Lipiodol mixture is a key point for the treatment of hepatocellular carcinoma (HCC). We therefore prepared a new, improved emulsion of Lipiodol containing a high dose of cis-diamminedichloroplatinum (CDDP) and epirubicin by replacing the ionic contrast medium (Urografin 67) with a nonionic contrast medium (Iopamidol; Iopamiron 300) and adding phosphatidyl choline. This CDDP-epirubicin-Lipiodol emulsion (CELE) was examined pharmacologically and chemically with the following results. The size of these particles is less than 10 microns (diameter) for up to 24 h; the release of 28%-34% of the CDDP and 80%-90% of the epirubicin was estimated in the dissolution test, and 85% of the CDDP and 35% of the epirubicin was retained in the organs in the moment calculation. CELE was injected into 58 HCC patients via a celiac angiographic catheter. In 36 of these patients, the CELE injection was followed by transcatheter arterial embolization (TAE) therapy. Following the administration of CELE as one-shot injection therapy for stage IV HCC, the 1-year survival rate was 59% and the 2-year survival rate was 27%. Moreover, in patients (stage II, 12; stage III, 8; stage IV, 16) who received CELE and subsequently underwent TAE therapy, the 1-year survival rate was 90% and the 2-year survival rate was 67%. The nonionic contrast medium with Lipiodol forms finer emulsified particles, and these particles are more capable of penetrating into the tumor. In addition, the greater pharmacological stability of these particles provides a slow-release effect and prolonged stability of their shape. Finally, theoretically, the use of two major anticancer agents such as CDDP and epirubicin showed a greater clinical effect in the treatment of HCC than either our earlier suspension or a single anticancer agent.