"Equity Repurchases and Corporate Value: Evidence from Different Legal Procedures in Japan" (in Japanese)

This paper empirically investigates which event can affect stock pricing through equity repurchases, the announcement of board meetings, the approval by general meetings of stockholders, or the incident of actual purchases, thereby clarifying the motivation behind equity repurchases. In particular, it attempts to exploit differences in legal procedures in Japanese corporate financing. The estimation results demonstrate that the repurchase based on the 1994 amendment to the Commercial Law is more consistent with the cash-flow hypothesis, while the repurchase made under the special code enforced in 1997 is more agreeable with the signaling hypothesis. No evidence is found for liquidity impacts of repurchases on stock pricing.

Asymptotic Learning Curve and Renormalizable Condition in Statistical Learning Theory

Bayes statistics and statistical physics have the common mathematical structure, where the log likelihood function corresponds to the random Hamiltonian. Recently, it was discovered that the asymptotic learning curves in Bayes estimation are subject to a universal law, even if the log likelihood function can not be approximated by any quadratic form. However, it is left unknown what mathematical property ensures such a universal law. In this paper, we define a renormalizable condition of the statistical estimation problem, and show that, under such a condition, the asymptotic learning curves are ensured to be subject to the universal law, even if the true distribution is unrealizable and singular for a statistical model. Also we study a nonrenormalizable case, in which the learning curves have the different asymptotic behaviors from the universal law

A Case of Advanced Hepatocellular Carcinoma with Portal Vein Tumor Thrombus Refractory to Epirubicin That Showed Marked Decrease in Tumor Markers after Transcatheter Arterial Infusion with Miriplatin

Miriplatin, a cisplatin derivative with a high affinity for iodized ethyl esters of fatty acids from poppy seed oil, is a novel chemotherapeutic agent designed for use in the transarterial treatment of hepatocellular carcinoma (HCC). Here, we describe transcatheter arterial infusion (TAI) using miriplatin to treat a case of advanced HCC with portal vein tumor thrombus (PVTT) refractory to TAI with epirubicin. A 66-year-old man with advanced hepatitis C virus-related HCC with PVTT in the right lobe of the liver was treated with TAI with epirubicin suspended in iodized oil; however, tumor marker levels (alpha-fetoprotein and des-gamma-carboxy protein) did not decrease. Next, he was treated twice with TAI with miriplatin suspended in iodized oil. The tumor marker levels markedly decreased to a nearly normal range and the size of the main tumor was markedly reduced according to dynamic computed tomography. No serious adverse events occurred during the course of treatment with TAI and miriplatin. Therefore, we suggest that TAI with miriplatin is a safe and effective treatment option for advanced HCCs refractory to TAI with epirubicin

Runx3 regulates folliculogenesis and steroidogenesis in granulosa cells of immature mice

We previously demonstrated that female Runx3 knockout (Runx3-/-) mice were anovulatory and their uteri were atrophic and that Runx3 mRNA was expressed in granulosa cells. To clarify how Runx3 regulates folliculogenesis and ovulation, we examine the effects of Runx3 knockout on the gene expression of growth factors associated with folliculogenesis and enzymes associated with steroidogenesis. In Runx3-/- mouse ovaries, the numbers of primary and antral follicles were lower than those in wild-type (wt) mice at 3 weeks of age, indicating that the loss of Runx3 affects folliculogenesis. The expression of genes encoding activin and inhibin subunits (Inha, Inhba and Inhbb) was also decreased in ovaries from the Runx3-/- mice compared with that in wt mice. Moreover, the expression of the genes Cyp11a1 and Cyp19a1 encoding steroidogenic enzymes was also decreased. In cultured granulosa cells from 3-week-old mouse ovaries, Cyp19a1 mRNA levels were lower in Runx3-/- mice than those in wt mice. Follicle-stimulating hormone (FSH) treatment increased Cyp19a1 mRNA levels in both wt and Runx3-/- granulosa cells in culture but the mRNA level in Runx3-/- granulosa cells was lower than that in wt ones, indicating that granulosa cells could not fully function in the absence of Runx3. At 3 weeks of age, gonadotropin α subunit, FSHβ subunit and luteinizing hormone (LH) β subunit mRNA levels were decreased in Runx3-/- mice. These findings suggest that Runx3 plays a key role in female reproduction by regulating folliculogenesis and steroidogenesis in granulosa cells

The effect of pegylated interferon-alpha2b and ribavirin combination therapy for chronic hepatitis C infection in elderly patients

<p>Abstract</p> <p>Background</p> <p>The clearance of hepatitis C virus infection by interferon therapy significantly reduces the incidence of hepatocellular carcinoma and death in elderly chronic hepatitis patients. However, there are few reports concerning the efficacy and safety of pegylated interferon-alpha2b plus ribavirin combination therapy in elderly patients. The aims of the present study were to examine the effect and safety of pegylated interferon-alpha2b plus ribavirin combination therapy in 427 patients with chronic hepatitis C infection. We compared the rates of sustained virological response--defined as the absence of detectable hepatitis C virus in serum 24 weeks after the treatment ended--and the treatment discontinuation rate between 319 younger patients aged < 65 years and 108 elderly patients aged ≥ 65 years. We also examined the factors contributing to a sustained virological response.</p> <p>Results</p> <p>There was no significant difference in the sustained virological response rate between younger patients and elderly patients according to their hepatitis C virus genotype (41.5% (100/241) and 40.7% (35/86) for genotype 1; <it>P </it>= 0.899, 89.7% (70/78) and 86.4% (19/22) for genotype 2; <it>P </it>= 0.703, respectively). There was also no significant difference in the treatment discontinuation rate between the two age groups (10.3% (33/319) and 13.9% (15/108), respectively; <it>P </it>= 0.378). There were no serious adverse events requiring hospitalization. The factors contributing significantly to a sustained virological response in elderly patients were gender, hepatitis C virus genotype, platelet count, and the presence of a rapid or early virological response (undetectable hepatitis C virus in serum at weeks 4 or 12 of treatment, respectively). However, upon multivariate analysis, the presence of an early virological response was the only significant factor (odds ratio: 0.115, 95% confidence interval: 0.040- 0.330, <it>P </it>< 0.001).</p> <p>Conclusions</p> <p>The efficacy and safety of pegylated interferon-alpha2b plus ribavirin combination therapy in elderly patients are not always inferior to those in younger patients. Obtaining an early virological response may be essential to achieve a sustained virological response in elderly patients with chronic hepatitis C infection.</p

AYUMS: an algorithm for completely automatic quantitation based on LC-MS/MS proteome data and its application to the analysis of signal transduction

BACKGROUND: Comprehensive description of the behavior of cellular components in a quantitative manner is essential for systematic understanding of biological events. Recent LC-MS/MS (tandem mass spectrometry coupled with liquid chromatography) technology, in combination with the SILAC (Stable Isotope Labeling by Amino acids in Cell culture) method, has enabled us to make relative quantitation at the proteome level. The recent report by Blagoev et al. (Nat. Biotechnol., 22, 1139–1145, 2004) indicated that this method was also applicable for the time-course analysis of cellular signaling events. Relative quatitation can easily be performed by calculating the ratio of peak intensities corresponding to differentially labeled peptides in the MS spectrum. As currently available software requires some GUI applications and is time-consuming, it is not suitable for processing large-scale proteome data. RESULTS: To resolve this difficulty, we developed an algorithm that automatically detects the peaks in each spectrum. Using this algorithm, we developed a software tool named AYUMS that automatically identifies the peaks corresponding to differentially labeled peptides, compares these peaks, calculates each of the peak ratios in mixed samples, and integrates them into one data sheet. This software has enabled us to dramatically save time for generation of the final report. CONCLUSION: AYUMS is a useful software tool for comprehensive quantitation of the proteome data generated by LC-MS/MS analysis. This software was developed using Java and runs on Linux, Windows, and Mac OS X. Please contact [email protected] if you are interested in the application. The project web page is