Content of mutant mitochondrial DNA and organ dysfunction in a patient with a MELAS subgroup of mitochondrial encephalomyopathies

A point mutation of mitochondrial tRNA^Leu(UUR) gene is responsible for a MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) subgroup of mitochondrial encephalomyopathies. In most cases, the mutant mitochondrial DNA (mtDNA) coexists with normal mtDNA in a heteroplasmic manner. In order to quantify the content of mutant mtDNA, we developed a quantitative method of PCR. Using this method, the distribution of the mutant mtDNA was examined in 32 different tissues among 18 autopsied organs from a patient with MELAS, who had shown hypophyseal dysfunction. The percentage of the mutant mtDNA at nucleotide number 3243 in each tissue was ranged between 22% and 95%. The content of the mutant mtDNA was at the highest (95%) in the hypophysis and higher in the cerebral cortex than in the white matter. This study shows a possible correlation of tissue dysfunction with accumulation of the mutant mtDNA within the brain.     

Combined Use of Dendritic Cells Enhances Specific Antileukemia Immunity by Leukemia Cell-Derived Heat Shock Protein 70 in a Mouse Model with Minimal Residual Leukemia Cells

We have reported that immunotherapy using leukemia cell-derived heat shock proteins (HSPs) is effective against minimal residual disease (MRD) after syngeneic stem cell transplantation (SCT) in mice. However, leukemia patients after SCT are usually immunocompromised and immunologically tolerant to leukemia cells. We investigated whether the use of dendritic cells (DCs) in combination with HSP70 enhances cytotoxicity against B-cell leukemia cell line A20 in mice after syngeneic SCT. All unimmunized mice died of leukemia early after A20 cell inoculation, whereas mice immunized with HSP70 or HSP70-pulsed DCs survived significantly longer. Although only 60% of the HSP70-immunized mice survived, all mice immunized with HSP70-pulsed DCs survived without MRD. In addition, the cytotoxicities against A20 cells for splenocytes from mice immunized with HSP70-pulsed DCs were significantly higher than those of HSP70-immunized mice, and the cytotoxicities against A20 cells were significantly blocked by anti-CD8 antibody and by major histocompatibility complex class I antibody, but not by anti-CD4 antibody. Moreover, abnormalities were detected in neither the biochemical data nor the histopathologic findings. These findings indicate that the combined use of DCs and leukemia cell-derived HSP70 enhances the antileukemia effect by inducing the specific cytotoxicities of CD8+ cytotoxic T-cells, thereby eradicating MRD effectively and safely, even in an immunocompromised state after syngeneic SCT. This approach may thus be useful for further application of HSP in leukemia patients after autologous SCT.     

Evaluation of 10 commercial diagnostic kits for in vitro expressed hepatitis B virus (HBV) surface antigens encoded by HBV of genotypes A to H

Genetic variability of the hepatitis B virus (HBV) constitutes one of the major challenges for diagnosis of HBV infection. It is plausible that amino acid substitutions in the "a" determinant of the HBV surface antigen (HBsAg) that affect antigenic sites, whether originating from genetic diversity or from mutations in the HBV strain itself, will affect the sensitivity of some diagnostic kits. In fact, recent studies have indicated that some diagnostic kits had false negative results with particular HBsAg mutants. There have been, however, few substantial studies evaluating sensitivities of diagnostic kits to the HBsAg encoded by different HBV genotypes. Our recent study found that 10 diagnostic kits available in Japan were able to detect HBsAg irrespective of whether it originated from HBV genotypes A, B or C, with the latter two genotypes being the dominant species in East Asia. In this study, we extended our previous efforts by assessing the ability of diagnostic kits to detect recombinant HBsAg derived from HBV genotypes A to H. Our results demonstrated that 9 out of 10 diagnostic kits evaluated were able to detect as low as 0.2 International Units (IU)/ml HBsAg, irrespective of HBV genotype. The genotypic differences in the HBV family thus appear to have little impact on the sensitivity of currently available HBsAg diagnostic kits.     

Determination of Prognostic Factors in Japanese Patients With Advanced Gastric Cancer Using the Data From a Randomized Controlled Trial,Japan Clinical Oncology Group 9912

Background.

In advanced gastric cancer (AGC), no globally accepted prognostic scoring system has been developed. Therefore, we explored baseline prognostic factors in Japanese AGC patients using the data from a randomized controlled trial, Japan Clinical Oncology Group (JCOG) 9912, which investigated the efficacy of systemic chemotherapy as a first-line treatment.

Patients and Methods.

Prognostic factors and prognostic indices for overall survival were screened and evaluated in patients enrolled in JCOG9912 using the Cox proportional hazard model. The Royal Marsden Hospital prognostic model was also applied to the JCOG9912 trial.

Results.

A total of 650 (92.3%) of the 704 patients randomized in the JCOG9912 trial, for whom complete data were available for multivariate analyses, was included in the present study (5-fluorouracil arm, n = 215; irinotecan plus cisplatin arm, n = 216; S-1 arm, n = 219). The median survival time (MST) for all patients was 11.8 months. To construct a prognostic index, we selected four risk factors by multivariate analysis: performance status ≥ 1, number of metastatic sites ≥ 2, no prior gastrectomy, and elevated alkaline phosphatase. MSTs were 17.0 months for patients categorized into the low-risk group, who had zero or one risk factor (n = 225); 10.4 months for patients in the moderate-risk group, who had two or three risk factors (n = 368); and 5.0 months for patients in the high-risk group, who had all four risk factors (n = 57).

Conclusion.

In the present study, we propose a new prognostic index for patients with AGC. This can be used for more appropriate patient stratification in future clinical trials.