Biomedical subjects

S Kojima

Publications and source records attributed to S Kojima.

At least 73 records · Page 4Linked to original sources

PubMed2001

Usefulness of the Kohlrausch-Williams-Watts stretched exponential function to describe protein aggregation in lyophilized formulations and the temperature dependence near the glass transition temperature.

PURPOSE: We studied the feasibility of using the Kohlrausch-Williams-Watts stretched exponential function (KWW equation) to describe protein aggregation in lyophilized formulations during storage. Parameters representing "mean aggregation time" (taua) and stretched exponential constant (betaa) were calculated according to the KWW equation by assuming that the time required for protein molecules to aggregate (tau) varies because of the fact that protein aggregation occurs at a rate that depends on the degree of protein deformation resulting from stresses created during freeze-drying. The temperature dependence of the parameters near the glass transition temperature was examined to discuss the possibility of predicting protein aggregation by accelerated testing. METHODS: Protein aggregation in lyophilized bovine serum gamma-globulin (BGG) formulations containing dextran or methylcellulose, at temperatures ranging from 10 to 80 degrees C, was followed by size-exclusion chromatography. RESULTS: Non-exponential BGG aggregation in lyophilized formulations could be described by the KWW equation. The taua and betaa, parameters changed abruptly around the NMR relaxation-based critical mobility temperature for formulations containing dextran and methylcellulose. In the glassy state, in contrast, the taua parameter of these formulations exhibited continuous temperature dependence. The parameter taur, as calculated from taua, and betaa, reflected differences in tau values between the two excipients. CONCLUSIONS: The results indicate that the parameter betaa is reflective of physical changes wihtin lyophilized formulations. Within the temperature range, during which no abrupt changes in betaa were observed, knowledge regarding the taua and betaa parameters allows the rate of protein aggregation to be predicted. The parameter taur was found to be useful in comparing the protein aggregation behavior of formulations having different taua and betaa values.

Algorithms↗

PubMed2001

Risk factors for chronic graft-versus-host disease after allogeneic stem cell transplantation in children.

We analyzed the incidence and risk factors for chronic graft-versus-host disease (GVHD) in 265 children undergoing allogeneic stem cell transplantation (SCT) who survived longer than 3 months post SCT. Patients transplanted from HLA-mismatched related donors and matched unrelated donors were included. Fifty-five patients developed chronic GVHD between 1 and 25 months after SCT, and the 5-year cumulative incidence of chronic GVHD was 22%. By multivariate analysis, acute GVHD (P = 0.004), malignant disease (P = 0.004), recipient age (> or =10 years) (P = 0.01) and a female donor to male recipient (P = 0.035) were significant risk factors for chronic GVHD. When acute GVHD was excluded from the multivariate analysis, malignant disease (P = 0.002) and older recipient age (P = 0.007) were identified. The incidence of chronic GVHD in this childhood study was lower than that observed in adults, and recipient age was an important factor in childhood SCT. The high incidence associated with malignant disease may be affected by changes in GVHD prophylaxis in order to ensure graft-versus-tumor effects.

Adolescent↗

PubMed2001

Correlation between HHV-6 infection and skin rash after allogeneic bone marrow transplantation.

We investigated whether a causal relationship exists between human herpesvirus 6 (HHV-6) and skin rash resembling acute graft-versus-host disease (GVHD) following bone marrow transplantation (BMT). Isolation of HHV-6 was used to monitor active HHV-6 infection in this study. We analyzed 25 episodes of skin rash in 22 recipients. All recipients were seropositive for HHV-6 before BMT. The onset of skin rash started prior to 30 days post transplantation (group A) in 15 of 25 cases, but after that (group B) in the remaining 10 cases. Twenty-five skin tissue samples were obtained from 22 recipients. The HHV-6 genome was detected in four of 15 skin samples from group A, but not detected in those from group B. HHV-6 was isolated from 11 of 22 recipients around 2 to 3 weeks after BMT (range 14 to 28 days after BMT). HHV-6 was isolated at a time between 10 days before and after the onset of skin rash (skin rash-related viremia) in nine cases in group A. Meanwhile, no skin rash-related viremia was observed in group B. Of the four recipients with positive detection of HHV-6 genome in their skin tissue (group A), two had HHV-6 viremia at the same time. The association between the timing of HHV-6 infection and the onset of skin rash was analyzed statistically. HHV-6 viremia (skin rash-related viremia) was found in nine of 15 (60%) cases in group A, compared with none of 10 (0%) cases in group B. This difference was statistically significant (P = 0.008). Moreover, HHV-6 infection (skin rash-related viremia and/or positive detection of HHV-6 DNA in skin tissue) was demonstrated in 11 of 15 (73.3%) cases in group A, compared with none of 10 (0%) cases in group B (P = 0.001). Thus, this study suggests that HHV-6 may be involved in the development of skin rash in the first month after allogeneic BMT.

Adolescent↗

PubMed2001

Myelodysplastic syndrome in childhood: a retrospective study of 189 patients in Japan.

We report a retrospective analysis of children with myelodysplastic syndrome (MDS) diagnosed between 1990 and 1997 in Japan. In total, 189 patients were enrolled: 122 cases of primary MDS (26 RA, 18 RAEB, 25 RAEBt, 53 CMML/JMML), 24 cases with constitutional predisposition to MDS, and 43 cases of therapy-related MDS (t-MDS). The frequency of pediatric MDS was estimated to be 7.7% of all leukemias. Cytogenetic abnormalities were observed in 41% of primary MDS and 90% of t-MDS cases. The 4-year survival rate, estimated by Kaplan-Meier analysis, for primary RA was 78.9%, while other types of MDS and JMML had rates lower than 40%, and t-MDS showed an even more unfavorable prognosis. In primary MDS, the survival rate of patients with cytogenetic abnormalities was significantly lower. Among prognostic variables by IPSS, only the cytogenetic pattern was useful for predicting outcome in childhood MDS. There was no apparent advantage to chemotherapy for RA, and the survival rate in patients with primary RA, JMML, or t-MDS receiving stem cell transplantation was significantly higher. More precise designs of our diagnostic and classification systems, as well as therapeutic trials in large-scale prospective studies, are necessary for further improvements in MDS outcome.

Adolescent↗

PubMed2001

Unrelated donor marrow transplantation in children with severe aplastic anaemia using cyclophosphamide, anti-thymocyte globulin and total body irradiation.

We report a favourable outcome in 15 patients with severe aplastic anaemia (SAA) who were < 20 years of age and who underwent bone marrow transplantation (BMT) from a human leucocyte antigen (HLA)-matched unrelated donor. All patients were non-responders to intensive immunosuppressive therapy (IST) and were multiply transfused. The conditioning regimen consisted of cyclophosphamide (60 mg/kg/d, on d -4 and -3), anti-thymocyte globulin (2.5 mg/kg/d, on d -5 to -2) and total body irradiation (2.5 Gy x 2/d, on d -2 and -1). Patients received cyclosporine and methotrexate for prophylaxis of graft-versus-host disease (GVHD), except for the last four who received tacrolimus instead of cyclosporine. Donor/recipient pairs were identical for HLA class I and II antigens by serological typing, but four pairs were found to have a mismatch at the HLA-A, -B or -DRB1 locus by high-resolution typing. All patients achieved rapid engraftment and are alive at 2-86 months after transplantation (median follow-up, 51 months). Moderate to severe acute GVHD occurred in 5 out of 15 patients (33%); only one patient developed extensive chronic GVHD. Considering our encouraging results, unrelated donor transplantation for SAA is recommended as a salvage therapy in non-responders to IST.

Adolescent↗

PubMed2001

Prospective monitoring of the Epstein-Barr virus DNA by a real-time quantitative polymerase chain reaction after allogenic stem cell transplantation.

Epstein-Barr virus (EBV)-related lymphoproliferative disorder (LPD) is a serious complication of haematopoietic stem cell transplantation (HSCT). To clarify the frequency, natural course and risk factors for LPD, we prospectively monitored 38 allogeneic (allo)-HSCT patients, focusing on the use of anti-thymocyte globulin (ATG). We used a recently developed real-time polymerase chain reaction assay to monitor EBV genome load. The subjects consisted of 19 patients given ATG for conditioning and 19 patients not given ATG. Of the 19 patients given ATG, 47.4% (nine patients) had a significant increase in EBV genome load (10(2.5) copies/microg DNA). Of these nine patients, two developed LPD. Therefore, 10.5% of the patients receiving allo-HSCT with ATG developed LPD. In contrast, none of the 19 patients without ATG had a significantly increased EBV load. The increases in viral load were observed in the second or third month after HSCT. We found that the peak viral loads of LPD patients were > 10(4.0 ) copies/microg DNA. On the other hand, the viral loads of most patients with no symptoms were < 10(2.5) copies/microg DNA. In conclusion, routine monitoring of EBV load during the second and third months after transplantation may benefit patients undergoing HSCT with ATG. We propose that an EBV load > 10(2.5) copies/microg DNA is the reactivation of EBV, and that an EBV load > 10(4.0) copies/microg DNA is indicative of developing LPD.

Adolescent↗

PubMed2001

Involvement of complement and fibronectin in eosinophil-mediated damage to Nippostrongylus brasiliensis larvae.

By using IL-5 transgenic mice, it has been shown that eosinophils might play a key role in elimination of larval stages of nematode infections. The present study was carried out to clarify molecular mechanisms involved in the eosinophil-mediated killing of Nippostrongylus brasiliensis larvae. The larvicidal activity was observed in the presence of normal serum in vitro. Electron microscopic observations revealed firm attachment of eosinophils to the cuticular surface of larvae, which was damaged by electron-dense materials released from eosinophils. The larvicidal activity was abrogated by heat- or zymosan-treatment of the serum, whereas depletion of IgG or IgM from the serum did not interfere with eosinophil adhesion and killing. Moreover, pretreatment of eosinophils with monoclonal antibodies against CD11b or VLA-4 inhibited the eosinophil-mediated killing of larvae. Immunofluorescent staining demonstrated the deposition of C3c and plasma fibronectin on the cuticle of the larvae. These results indicate that interactions between CD11b and VLA-4 and their respective counter-ligands deposited on the cuticle are essential in eosinophil-mediated adhesion and damage to larvae of N. brasiliensis.

Animals↗

PubMed2001

Protective immunity to Schistosoma japonicum infection depends on the balance of T helper cytokine responses in mice vaccinated with gamma-irradiated cercariae.

Although the strain difference in protection of mice to Schistosoma mansoni infection has been described, limited information is available in the case of Schistosoma japonicum. In the present study, we compared the protective immunity to S. japonicum infection and cytokine production in various strains of mice vaccinated with gamma-irradiated cercariae. A significant reduction in worm recovery was observed in male and female mice of DBA/2 at a 6-week interval between vaccination and a challenge infection, whereas vaccinated mice of C57BL/6, C57BL/10, (C57BL/6 x DBA/2) F1 (B6D2F1) and (C57BL/10 x DBA/2) F1 (B10D2F1) showed no detectable level of protection. No sex-linked difference in development of resistance was observed in any of the strains so far examined. Vaccination with gamma-irradiated cercariae twice with a 3-week interval also induced significant protection against a challenge infection in DBA/2 but not in BALB/c or C57BL/6 strains. Further studies demonstrated that spleen cells of vaccinated C57BL/6 mice produced lower levels of IFN-gamma compared to the cells of vaccinated BALB/c and DBA/2. On the other hand, production of IL-10 by spleen cells was relatively higher in BALB/c mice than in the other two strains. Macrophages that had been stimulated with spleen cell culture supernatants derived from vaccinated DBA/2 damaged schistosomula more effectively than cells stimulated with supernatants derived from the other strains. These results suggest that different levels of protection observed among strains of mice depend on the balance of cytokine responses which consequently activate or suppress macrophage-mediated damage to schistosomula.

Animals↗

PubMed2001

PCR-based ELISA technique for malaria diagnosis of specimens from Thailand.

We performed a field evaluation of polymerase chain reaction (PCR)-based enzyme-linked immuno-sorbent assays (ELISA) for the diagnosis of malaria. A commercially available PCR-ELISA microplate hybridization (MPH) assay was used. Blood specimens were collected from 300 volunteers seeking care at malaria clinics in Thailand. Examination of 200 high power fields by Giemsa-stained thick and thin smear (GTTS) revealed 51 P. falciparum (Pf), 45 P. vivax (Pv), seven mixed Pf-Pv infections. These plus a random sample of 48 GTTS-negative specimens were selected for this study. All 151 specimens were processed for parasite DNA extraction and assayed by PCR-MPH. The target DNA sequence of the 18S small subunit ribosomal RNA (SSUrRNA) gene was amplified by PCR and hybridized with species-specific probes for Pf, Pv, P. malariae (Pm) and P. ovale (Po) immobilized in the wells of the microtiter plate and detected by colorimetric assay. Colour development was assessed at an optical density (OD) of 405 nm. An absorbance reading of > or = 0.1 was used as a positive cut-off. In comparison with GTTS results, PCR-MPH sensitivity was 91.4% (53/58, 95% CI 84.2-98.6) for Pf, 94.2% (49/52, 87.9-100) for Pv and specificity was 95.8% (46/48, 95% CI 90.2-100). There was statistically significant positive correlation between parasite densities < or = 7000/microl blood and absorbance reading, suggestive of PCR-MPH being semiquantitative. PCR-MPH also detected additional Pf and Pv cases as well as Pm and Po.

Adolescent↗

PubMed2001

Chemoprevention of hepatocellular carcinoma: concept, progress and perspectives.

Hepatocellular carcinoma (HCC) often develops in patients with chronic liver diseases associated with hepatitis B (HBV) and hepatitis C (HCV) virus infections with high incidences. Particularly, post-therapeutic recurrence encountered after the curative treatment of the preceding HCC may limit the prognosis. Thus, prevention of HCC is of great significance. In the present review, immunopreventions with alpha-interferon and glycyrrhizin, as well as chemoprevention with acyclic retinoid, are discussed. alpha-Interferon prevents the development of HCC not only in patients with a long-term elimination of HCV (sustained virological responders), but in ones with normalized serum aminotransferases (sustained biochemical responders). Glycyrrhizin also suppresses serum aminotransferases and thereby prevents the tumor development, even though the compound does not have antiviral activity for HBV or HCV by itself. Therefore, suppression of hepatic necroinflammation by these drugs may serve to prevent hepatocarcinogenesis. In contrast, acyclic retinoid suppresses the post-therapeutic recurrence in cirrhotic patients who underwent curative treatment of preceding tumors. The retinoid induces the disappearance of serum lectin-reactive alpha-fetoprotein (AFP-L3), a tumor marker indicating the presence of unrecognizable tumors in the remnant liver, suggesting a deletion of such minute (pre)malignant clones (clonal deletion). As a molecular mechanism of the clonal deletion, a novel mechanism of apoptosis induction by the retinoid via tissue transglutaminase is implicated. In future, a combination of immunopreventive and chemopreventive therapies may give a clue to the further advances of cancer prevention, and thereby to the improvement of the prognosis of cirrhotic patients.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2001

Solitary fibrous tumor of the prostate.

An extremely rare case of solitary fibrous tumor of the prostate is presented. The patient underwent a radical retropubic prostatectomy and has remained well with no evidence of recurrence during the last 18 months. This is the fifth reported case of such a lesion arising in the prostate.

Adult↗

PubMed2001

Low-density lipoprotein apheresis and changes in plasma components.

Several different techniques of low-density lipoprotein (LDL) apheresis are available for management of severe hypercholesterolemia. Among them, the adsorption system with a dextran-sulfate cellulose (DSC) column is most widely used. In addition to adsorption of LDL, DSC adsorbs plasma constituents that have the following characteristics: proteins containing apolipoprotein B (Lp[a]); proteins involved in the initial contact phase of the intrinsic coagulation pathway (coagulation factor XII, high-molecular-weight kininogen and prekallikrein); factors with lipophilic characteristics (coagulation factor VII, coagulation factor VIII, and vitamin E); and proteins with adhesive or other characteristics (von Willebrand factor, fibronectin, serum amyloid P component, hepatocyte growth factor). The adsorption of these proteins seems to ameliorate prevention or regression of atherosclerosis. Moreover, plasma treatment by the DSC column may be useful for treatment of inexorable diseases, such as amyloidosis. On the other hand, the DSC column generates bradykinin by activation of the initial contact phase of the intrinsic coagulation pathway. Bradykinin generation may explain the functional improvement in the circulatory system, as well as hypotension during LDL apheresis, which is observed in patients taking ACE inhibitors.

Adsorption↗

PubMed2001

Acute changes in plasma levels of hepatocyte growth factor during low-density lipoprotein apheresis.

Hepatocyte growth factor (HGF) is a mesenchyme-derived pleiotropic factor, and angiogenesis is included in a variety of its functional effects. HGF levels were measured in 5 sessions of low-density lipoprotein (LDL) apheresis in 3 patients with severe hypercholesterolemia. Blood was collected at the start (T0) and at 1,000 ml (T1), 2,000 ml (T2), and 3,000 ml (T3) plasma treatments. During LDL apheresis, HGF levels increased from 1.59 +/- 0.78 (mean +/- SE, n = 5) ng/ml at T0 to 6.64 +/- 0.97 at T1, 6.28 +/- 0.97 at T2, and 5.20 +/- 0.94 at T3. In one apheresis session, HGF increased immediately at the 100 ml plasma treatment stage. HGF was adsorbed completely by a dextran-sulfate (DS) column. Despite the adsorption by the DS column, HGF in the patient blood increased to the levels with functional effects. The improvement of ischemic symptoms due to LDL apheresis may be related to the angiogenic activities of HGF.

Analysis of Variance↗

PubMed2001

Prevention of rat hepatic fibrosis by the protease inhibitor, camostat mesilate, via reduced generation of active TGF-beta.

BACKGROUND & AIMS: Proteolytic release and activation of latent transforming growth factor beta (TGF-beta) by the hepatic stellate cells (HSCs) are key events for pathogenesis of hepatic fibrosis, and protease inhibitors suppress TGF-beta generation by cultured HSCs, suggesting their potential use as antifibrogenic agents. We explored this idea using camostat mesilate, a serine protease inhibitor, to determine its effects and mechanisms of action in vivo. METHODS: Camostat mesilate was either added to cultured rat HSCs or administered orally to rats during porcine serum treatment, followed by overexpression of urokinase. We measured cellular and hepatic levels of plasmin, TGF-beta, TGF-beta activity, activated HSC markers (increased cell number, morphologic change, and expression of both alpha-smooth muscle actin and collagen(alpha2)[I]), and fibrosis (Azan-staining and quantification of hydroxyproline content). RESULTS: Camostat mesilate (500 micromol/L) inhibited generation of TGF-beta by suppressing plasmin activity and reduced the activity of TGF-beta, which blocked in vitro activation of HSCs. In the in vivo model, camostat mesilate (1-2 mg/g of diet) markedly attenuated an increase in hepatic plasmin and TGF-beta levels, HSC activation, and hepatic fibrosis without apparent systemic or local side effects, all of which were reverted by restoration of hepatic plasmin activity. CONCLUSIONS: Camostat mesilate prevents porcine serum-induced rat hepatic fibrosis via a profound reduction in TGF-beta generation.

Animals↗

PubMed2001

Mechanism of retarded liver regeneration in plasminogen activator-deficient mice: impaired activation of hepatocyte growth factor after Fas-mediated massive hepatic apoptosis.

Urokinase-type plasminogen activator (uPA) is implicated in the regulation of hepatic regeneration by activating hepatocyte growth factor (HGF). Here, we investigated its role in the hepatic regeneration after Fas-mediated massive hepatocyte death employing mice deficient in either uPA or its inhibitor, plasminogen activator inhibitor-1 (PAI-1). We measured kinetics of hepatic levels of proliferating cell nuclear antigen (PCNA)-labeling index, plasmin activity, mature HGF, and its phosphorylated receptor, c-Met. In the genetically targeted and wild-type mice, hepatocytes fell into the same extent of apoptosis 6 to 12 hours after an intraperitoneal injection with anti-Fas antibody, as judged from histologic analysis and a histon-DNA enzyme-linked immunosorbent assay (ELISA). In the wild-type mice, mature HGF emerged in the liver 6 hours following anti-Fas injection, and hepatic PCNA-labeling index started to increase following 24 hours and peaked at 48 hours. In the uPA(-/-) mice, emergence of mature HGF was delayed 12 hours and hepatic regeneration peaked at 96 hours. Supplementation with the uPA gene to the uPA(-/-) mice by in vivo lipofection restored hepatic plasmin levels, and improved a delay in the expression of both mature HGF and phosphorylated c-Met, accompanying a normal rate of liver regeneration. In contrast, PAI-1(-/-) mice showed accelerated liver regeneration; mature HGF emerged as early as 3 hours, and PCNA-labeling index increased at 24 hours. This accelerated regeneration was abolished by administration with anti-HGF antibody. These results strongly suggest a physiologic role of uPA in the proteolytic maturation of HGF, and thereby in hepatic regeneration after Fas-mediated massive hepatocyte death.

Animals↗

PubMed2001

Does stent design affect probability of restenosis? A randomized trial comparing Multilink stents with GFX stents.

BACKGROUND: Experimental studies have revealed that stent configuration influences intimal hyperplasia. The purpose of this study was to evaluate clinical outcomes for 2 stent designs in a randomized trial with quantitative coronary angiography (QCA) and intravascular ultrasonography (IVUS). METHODS: We randomly assigned 100 patients with 107 lesions and symptomatic coronary artery disease to deployment of a Multilink stent (Advanced Cardiovascular Systems, Guidant, Santa Clara, Calif) or a GFX stent (Applied Vascular Engineering, Santa Rosa, Calif) with IVUS guidance. QCA and IVUS studies were performed before and after intervention and at follow-up (4.2 +/- 1.0 months). RESULTS: There were no significant differences in baseline characteristics and QCA and IVUS parameters before and after intervention between the 2 groups. However, minimal lumen diameter at follow-up was significantly larger in the Multilink group (2.46 +/- 0.59 vs 2.08 +/- 0.79 mm, P <.05). Maximal in-stent intimal hyperplasia was significantly larger in the GFX group (2.9 +/- 1.7 vs 1.8 +/- 1.2 mm(2), P <.01). The restenosis rate differed between the 2 groups (Multilink 4% vs GFX 26%, P =.003). In multiple stepwise logistic regression analysis, the only predictor that significantly correlated with restenosis was stent type (P <.01). The odds ratio for the GFX stent-treated vessels was 18.65 (95% confidence interval 2.10-165.45). CONCLUSIONS: With deployment of the GFX stent, a thicker neointima develops within the stent. Stent configuration may affect clinical outcomes.

Aged↗

PubMed2001

Involvement of nitric oxide in the ocular hypotensive action of nipradilol.

PURPOSE: To evaluate the role of nitric oxide (NO) in the mechanism of the ocular hypotensive action of nipradilol, a beta-blocker with alpha( 1)-blocking activity. METHODS: Change in intraocular pressure (IOP) of albino rabbits was measured after a single application of carboxy-PTIO (c-PTIO), an NO trapping agent. Next, IOP change was measured every hour for 5 hours after the instillation of 0.25% nipradilol into one of the eyes with and without c-PTIO pretreatment of both eyes. IOP change induced by desnitro-nipradilol was also examined. The outflow facility and uveoscleral outflow were determined by two-level constant pressure and anterior chamber perfusion methods before and at 3 hours after the application of nipradilol with and without c-PTIO pretreatment. RESULTS: Topical administration of c-PTIO showed no significant effect on IOP. Unilateral instillation of nipradilol reduced IOP significantly compared with control eyes with a maximum reduction of 3.6 mmHg and effect duration of 3 hours. Pretreatment with c-PTIO partially inhibited the reduction during an earlier period (1 approximately 2 hours) and completely at 3 hours. IOP change by desnitro-nipradilol was similar to that by nipradilol with c-PTIO pretreatment. Nipradilol increased both outflow facility and uveoscleral outflow at 3 hours, whereas pretreatment with c-PTIO inhibited both of these outflows. CONCLUSIONS: Results indicate that ocular hypotensive action by nipradilol during the relatively late period may be mainly due to enhancement of aqueous humor outflow by NO at least in the rabbits.

Administration, Topical↗

PubMed2001

Apoptosis induction by acyclic retinoid: a molecular basis of 'clonal deletion' therapy for hepatocellular carcinoma.

We have shown previously that administration of acyclic retinoid to cirrhotic patients who had undergone curative treatment of preceding hepatocellular carcinoma (HCC) induced the disappearance of serum lectin-reactive alpha-fetoprotein (AFP-L3) and subsequently reduced the incidence of second liver cancers. AFP-L3 is a tumor marker that indicates the presence of occult tumors below the detection limit by diagnostic images. Therefore, we have proposed a new concept of 'clonal deletion' therapy with acyclic retinoid for the cancer chemoprevention against HCC. Such eradication of AFP-L3-producing latent malignant (or premalignant) cells from the liver suggested a new strategy to prevent HCC, which may be involved in the same category as cancer chemotherapy. In the present series of studies, we explored the molecular mechanism of 'clonal deletion' and found a novel mechanism of apoptosis induction by the retinoid. We have demonstrated a modification of a retinoid receptor, RXRalpha, by mitogen-activated protein (MAP) kinase-dependent phosphorylation, resulting in the loss of transactivating activity. This may lead HCC cells to be resistant to natural retinoic acid. However, acyclic retinoid restored the function of phosphorylated RXRalpha and induced its downstream pro-apoptotic genes including tissue transglutaminase, an enzyme that is implicated in apoptosis. Tissue transglutaminase-dependent apoptosis in HCC cells was independent of the activation of caspases. This novel mechanism of retinoid-induced apoptosis may give a clue to understand the molecular mechanism of clonal deletion.

Antineoplastic Agents↗