Biomedical subjects

Masanobu Nakata

Publications and source records attributed to Masanobu Nakata.

13 recordsLinked to original sources

PubMed2006

A phase II study of VEPA/FEPP chemotherapy for aggressive lymphoma in elderly patients: Japan Clinical Oncology Group Study JCOG9203.

The Lymphoma Study Group (LSG) of the Japan Clinical Oncology Group conducted a phase II trial of LSG12 therapy for 45 elderly patients with aggressive lymphoma to clarify whether LSG12 reduces severe infection without lowering the complete response (CR) rate in comparison with LSG4. LSG12, which consisted of a regimen of vincristine, cyclophosphamide, prednisolone, doxorubicin, vindesine, etoposide, and procarbazine (VEPA/FEPP), excluded bleomycin and methotrexate of LSG4 therapy, reduced the dosages of doxorubicin and cyclophosphamide, and increased etoposide and procarbazine dosages instead. Inclusion criteria consisted of a patient age of 70 to 75 years, a World Health Organization performance status of 0 to 2, and acceptable organ function. The treatment was completed in 47% of the patients and terminated early for disease progression in 20% and for toxicity in 16%. The CR rate was 60% (95% confidence interval [CI], 44%-74%). The 5-year overall survival (OS) rate was 42% (95% CI, 27%-57%), and the median OS time was 4.3 years. Leukopenia of grade 3 to 4 occurred in 98% of the patients, and severe infection occurred in 9%. Eight patients with hepatitis C virus (HCV) antibody showed no severe hepatic toxicity and had a better CR or OS rate than the 37 HCV-negative patients. Although the outcomes of LSG12 met our expectations with a reduction in severe infection and equivalent CR and OS outcomes compared with LSG4 and CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone), the possibility of a regimen more beneficial than LSG12 for aggressive lymphoma in the elderly patient should be explored because of frequent hematologic toxicity and poor compliance in LSG12.

Aged↗

PubMed2005

Streptococcus pyogenes collagen type I-binding Cpa surface protein. Expression profile, binding characteristics, biological functions, and potential clinical impact.

The Streptococcus pyogenes collagen type I-binding protein Cpa (collagen-binding protein of group A streptococci) expressed by 28 serotypes of group A streptococci has been extensively characterized at the gene and protein levels. Evidence for three distinct families of cpa genes was found, all of which shared a common sequence encoding a 60-amino acid domain that accounted for selective binding to type I collagen. Surface plasmon resonance-based affinity measurements and functional studies indicated that the expression of Cpa was consistent with an attachment role for bacteria to tissue containing collagen type I. A cpa mutant displayed a significantly decreased internalization rate when incubated with HEp-2 cells but had no effect on the host cell viability. By utilizing serum from patients with a positive titer for streptolysin/DNase antibody, an increased anti-Cpa antibody titer was noted for patients with a clinical history of arthritis or osteomyelitis. Taken together, these results suggest Cpa may be a relevant matrix adhesin contributing to the pathogenesis of S. pyogenes infection of bones and joints.

Amino Acid Sequence↗

PubMed2005

Phase I study of radioimmunotherapy with an anti-CD20 murine radioimmunoconjugate ((90)Y-ibritumomab tiuxetan) in relapsed or refractory indolent B-cell lymphoma.

We conducted a phase I study to evaluate the safety and efficacy of radioimmunotherapy with yttrium-90-ibritumomab tiuxetan (Y2B8) in Japanese patients with relapsed or refractory indolent B-cell lymphoma. Indium-111-labeled ibritumomab tiuxetan (In2B8; 3.5 or 5 mCi [129.5 or 185 MBq]) was administered on day 1, followed by serial gamma-camera imaging to investigate the distribution of In2B8 in the whole body of patients and to judge the feasibility of Y2B8 administration. Y2B8 with a dose of 0.3 mCi/kg (11.1 MBq/kg) or 0.4 mCi/kg (14.8 MBq/kg) was administered on day 8. Grade 4 neutropenia and grade 3 thrombocytopenia were observed in three of nine of the patients evaluated for safety. Critical toxicities (prolonged thrombocytopenia or severe non-hematological toxicities) were observed in two of six patients in the 0.4 mCi/kg (14.8 MBq/kg) dose group but were not seen in any of the three patients in the 0.3 mCi/kg (11.1 MBq/kg) dose group. The non-hematological toxicities of the nine patients were of grade 2 or less, except in two patients who had been heavily treated previously. They experienced critical toxicities such as infection, diarrhea, hyponatremia and prolonged thrombocytopenia, as well as other frequent grade 2 non-hematological toxicities. Although the pharmacokinetic profiles were similar to those in the US study, one of the two patients was clarified retrospectively as showing abnormal biodistribution of In2B8 in the bone marrow, as judged by an independent third party panel of radiologists. Five of the 10 participants achieved complete responses or unconfirmed complete responses and two partial responses. In conclusion, the recommended dose of Y2B8 for the subsequent phase II study for Japanese patients is 0.4 mCi/kg (14.8 MBq/kg). This dose of radioimmunotherapy was feasible when patients with altered biodistribution of In2B8 were excluded, and it was highly effective. (Cancer Sci 2005; 96: 903-910).

Adult↗

PubMed2005

MsmR, a specific positive regulator of the Streptococcus pyogenes FCT pathogenicity region and cytolysin-mediated translocation system genes.

As a prerequisite for colonization or causing local infections, Streptococcus pyogenes (group A streptococci, GAS) need to specifically adhere to eukaryotic cell surfaces. Predominantly responsible adhesin genes are contained in a genotype-specific pattern within the FCT region of the GAS genome. In this study, MsmR, belonging to AraC/XylS type transcriptional regulators, was identified in the FCT region as a positive regulator of the major fibronectin-binding adhesin protein F2 in a serotype M49 strain. Compared with the wild-type strain, the msmR mutant showed reduced binding to immobilized fibronectin and decreased adherence to and internalization into human pharyngeal epithelial cells. These results suggested that altered levels of fibronectin-binding proteins in the mutant affect eukaryotic cell attachment and internalization. Complete transcriptome and reporter fusion assay data revealed that MsmR positively regulates FCT region genes including Nra and cytolysin-mediated translocation system genes. Consistent with the genetic data, the mutant showed attenuated streptolysin O activity and eukaryotic cell cytotoxity. Direct binding of recombinant MsmR to nga, nra/cpa and prtF2 promoter regions was confirmed by EMSA assays. As prior analysis demonstrated the Nra regulator negatively affects gene expression from the FCT region, MsmR and Nra appear to adversely control crucial virulence factor expression in GAS and thus contribute to a fine-tuned balance between local destructive process and metastatic spreading of the bacteria.

Bacterial Adhesion↗

PubMed2005

Global epithelial cell transcriptional responses reveal Streptococcus pyogenes Fas regulator activity association with bacterial aggressiveness.

The bacterial human pathogen Streptococcus pyogenes (group A streptococci, GAS) is able to adhere to, internalize into and cross-talk on multiple levels with its host cells. To gain insight into the Fas function in pathogenesis we used Affymetrix human genome DNA-arrays to measure temporal and global transcriptional responses of HEp-2 cells infected with M49 S. pyogenes wild-type bacteria and DeltafasX, an isogenic S. pyogenes two-component-signal-transduction system mutant. A modified stringent statistical analysis method identified a total of 86 HEp-2 cell genes as differentially transcribed upon infection over the investigated time course. Increased expression of genes encoding proteins involved in GAS host cell adherence and internalization (fibronectin, integrin-alpha5) was found as a common response. In contrast to earlier reports investigating other GAS serotype strains, Ras superfamily and RhoA pathways are exploited by M49 GAS, suggesting serotype specific interactions with the host cell cytoskeleton. Despite transcriptional induction, secreted IL-8 levels of deltafasX mutant infected cells were below those of non-infected cells, indicating an absence of Fas expression could be important for GAS tissue colonization and long-term intracellular persistence. Oppositely, activity of the S. pyogenes Fas-system apparently promotes high adherence and internalization rates, massive cytokine gene transcription and cytokine release, host cell apoptosis via a caspase-2 activation pathway, and cytotoxicity. Thus, the S. pyogenes Fas two-component signal transduction system could be involved in local tissue destruction and general bacterial aggressiveness towards host cells.

Apoptosis↗

PubMed2004

Autophagy defends cells against invading group A Streptococcus.

We found that the autophagic machinery could effectively eliminate pathogenic group A Streptococcus (GAS) within nonphagocytic cells. After escaping from endosomes into the cytoplasm, GAS became enveloped by autophagosome-like compartments and were killed upon fusion of these compartments with lysosomes. In autophagy-deficient Atg5-/- cells, GAS survived, multiplied, and were released from the cells. Thus, the autophagic machinery can act as an innate defense system against invading pathogens.

Autophagy↗

PubMed2004

Streptococcus pyogenes fibronectin-binding protein F2: expression profile, binding characteristics, and impact on eukaryotic cell interactions.

Some Streptococcus pyogenes (group A streptococci, GAS) strains have previously been shown to express the fibronectin-binding protein F2 instead of the functionally related but structurally dissimilar protein F1/SfbI. In this study, recombinant N-terminal and C-terminal portions and the two fibronectin-binding domains of protein F2 were used to assess affinity parameters of the interaction with fibronectin and its N-terminal 70-, 30-, and 45-kDa fragments. The association and dissociation equilibrium constants for both binding domains were in the nanomolar range, although the repeat domain of protein F2 exceeded the affinity of the unique domain by up to one order magnitude. Both domains primarily interacted with the 30-kDa fibronectin fragment. Using a prtF2 gene isogenic mutant of a serotype M49 GAS strain that does not harbor the protein F1/SfbI gene, the attachment values of whole bacteria to immobilized fibronectin and to HEp-2 epithelial cells were found to be 6- and 2-fold decreased, respectively. Reduction of prtF2 mutant internalization rates for eukaryotic cells exceeded the reduction of attachment rates, indicating an independent contribution of protein F2 to both processes. The prtF2 transcription and protein F2 expression profiles documented maximum expression at the transition to the stationary phase especially under aerobic growth condition. The protein F2 function as the major fibronectin-binding adhesin in a subset of GAS strains, its expression pattern, and highly specific interaction with fibronectin would be consistent with a status as an indispensable virulence factor for both earlier and later pathogenetic stages of GAS superficial infections.

Adhesins, Bacterial↗

PubMed2004

Transcriptome analysis and gene expression profiles of early apoptosis-related genes in Streptococcus pyogenes-infected epithelial cells.

Epithelial cells are the initial sites of host invasion by group A Streptococcus pyogenes (GAS), and GAS infection of epithelial cells has been suggested to induce apoptosis. We previously reported that the induction of apoptosis is strongly associated with the protein F1-mediated invasion. We present here the gene expression profiles of the human epithelial HEp-2 cells during GAS-induced apoptosis, using serial gene analysis of expression (SAGE) analysis and macroarray analysis of apoptosis-related genes. Serial gene analysis of expression revealed the downregulation of voltage-dependent anion channels 1 and 2 genes and the upregulation of the cytochrome c oxidase and calcium binding protein genes (calpactin, calgizzarin and programmed cell death 6). Macroarray analysis and quantitative RT-PCR analysis also revealed that the genes for IL-1beta, IL-12 p35, IL12 p40, and GM-CSF are also markedly induced by GAS invasion. Furthermore, caspase-1, -9, and -14 genes are significantly upregulated during GAS invasion. These observations indicated that apoptosis associated with GAS invasion is mainly induced by mitochondrial dysfunction and calcium regulation as well as by stress, and that these transcriptional controls may regulate the cellular response to GAS invasion.

Apoptosis↗

PubMed2003

Genome sequence of an M3 strain of Streptococcus pyogenes reveals a large-scale genomic rearrangement in invasive strains and new insights into phage evolution.

Group Astreptococcus (GAS) is a gram-positive bacterial pathogen that causes various suppurative infections and nonsuppurative sequelae. Since the late 1980s, streptococcal toxic-shock like syndrome (STSS) and severe invasive GAS infections have been reported globally. Here we sequenced the genome of serotype M3 strain SSI-1, isolated from an STSS patient in Japan, and compared it with those of other GAS strains. The SSI-1 genome is composed of 1,884,275 bp, and 1.7 Mb of the sequence is highly conserved relative to strain SF370 (serotype M1) and MGAS8232 (serotype M18), and almost completely conserved relative to strain MGAS315 (serotype M3). However, a large genomic rearrangement has been shown to occur across the replication axis between the homologous rrn-comX1 regions and between two prophage-coding regions across the replication axis. Atotal of 1 Mb of chromosomal DNA is inverted across the replication axis. Interestingly, the recombinations between the prophage regions are within the phage genes, and the genes encoding superantigens and mitogenic factors are interchanged between two prophages. This genomic rearrangement occurs in 65% of clinical isolates (64/94) collected after 1990, whereas it is found in only 25% of clinical isolates (7/28) collected before 1985. These observations indicate that streptococcal phages represent important plasticity regions in the GAS chromosome where recombination between homologous phage genes can occur and result not only in new phage derivatives, but also in large chromosomal rearrangements.

Attachment Sites, Microbiological↗

PubMed2003

Extragonadal germ cell tumors in Japan.

Extragonadal germ cell tumors (EGCT) represent only 2-5% of adult germ cell malignancies. Some publications from Asia have reported inferior treatment outcomes compared to data from an international study group. To ascertain whether this is generally the case, here we analyze treatment outcomes for 30 Japanese patients with EGCT. The medical records of 30 patients (25 nonseminomas and 4 pure seminomas) treated from 1992 to 2002 were reviewed retrospectively. All patients with seminoma achieved long survival except one who died of chemotherapy-related sepsis. Ten and 11 patients with EGCT presented with mediastinal and retroperitoneal primary sites, respectively. The 5-year overall survival (OS) and progression-free survival (PFS) for nonseminoma was 71% and 42%, respectively. The 5-year OS and PFS was 60% and 44%, respectively, for 10 patients with mediastinal nonseminoma, and 91% and 48%, respectively, for patients with retroperitoneal nonseminoma. Tumor marker values on day 7 were available for 19 patients. Among the 19 patients in whom AFP or beta-HCG were measured on day 7, the values had declined in 12 patients and were transiently elevated in 7 patients compared to pretreatment values. The transient elevations of tumor markers were significantly associated with poor OS (P = 0.02) and PFS (P = 0.008). The treatment outcome of Japanese patients with EGCT seemed to be comparable to that reported from international studies, suggesting no difference between ethnic groups. Transient tumor marker elevations on day 7 predict poor survival in EGCT patients and may be a useful parameter for identifying patients requiring more aggressive treatment.

Adolescent↗

PubMed2002

Molecular characterization of a novel fibronectin-binding protein of Streptococcus pyogenes strains isolated from toxic shock-like syndrome patients.

Group A Streptococcus pyogenes has surface-located fibronectin (Fn)-binding proteins known to be a major virulence factor, which adheres to and invades host cells. We present a novel Fn-binding protein of group A streptococcus serotype M3 and M18 strains isolated from patients with toxic shock-like syndrome (TSLS). By searching the whole genome sequence of an M3 strain from a TSLS patient, an open reading frame was found among the putative surface proteins. It possessed an LPXTG motif and Fn-binding repeat domains in the C-terminal region and was designated as FbaB (Fn-binding protein of group A streptococci type B). The fbaB gene was found in all M3 and M18 strains examined, although not in other M serotypes. Furthermore, FbaB protein was expressed on the cell surface of TSLS strains but not on non-TSLS ones. Enzyme-linked immunosorbent assay and ligand blotting revealed that recombinant FbaB exhibits a strong Fn-binding ability. An FbaB-deficient mutant strain showed 6-fold lower adhesion and invasion efficiencies to HEp-2 cells than the wild type. Moreover, mortality was decreased in mice infected with the mutant strain in comparison to the wild type. These data suggest that FbaB is etiologically involved in the development of invasive streptococcal diseases.

Adhesins, Bacterial↗

PubMed2002

Infection and pathogenesis of a murine strain of Escherichia coli with genetically introduced Shiga toxin type I operon in conventional mice.

The pathogenic response elicited by Shiga toxin type I (Stx1)-producing Escherichia coli was studied using an E. coli strain BME5 obtained from the natural flora of the mouse and used on three different strains of mice. The recombinant strain BME5/Stx1 was prepared by introducing the gene for Stx1. Following an oral inoculation of 1.0x10(9)cfu of BME5/Stx1 faecal recovery of 1.0x10(8)cfu/g faeces over 3 weeks was obtained. Neurologic signs as well as histopathological changes of the intestine and the kidneys were observed within 3 days after infection and elevated serum cytokines including IL-1beta and TNF-alpha were observed. Furthermore, the recombinant organisms were established in the intestine and showed exquisitely virulence when infected peritoneally in mice, while parent strain BME5 though colonized did not show any pathological changes. These results suggest that E. coli BME/Stx1 can colonize the mouse intestine under natural environment, and induced systemic neural changes and inflammation in the intestine and kidneys.

Administration, Oral↗

PubMed2002

[An elderly non-Hodgkin lymphoma patient with a massive tumor of the heart].

We report on an elderly patient with a malignant lymphoma forming a huge mass in the heart. An 82-year-old woman became aware of general fatigue and a cough in August 1999. Her right supraclavicular, bilateral axillary, and right inguinal lymph nodes were swollen. A hypodermical mass in the right frontal chest was detected. Her left axillary lymph node was biopsied. She was diagnosed as having non-Hodgkin lymphoma, diffuse large cell type, B-cell type. Computed tomography scans showed a markedly thickened right ventricular wall of the heart, swollen lymph nodes of the mediastinum, bilateral pleural effusions, and a tumor in the spleen. Lymphoma cells were found in the pleural effusion, and the lymphoma was diagnosed as clinical stage IV. Hypofunction of the heart, ejection fraction (EF) 49%, was demonstrated with transthoracic echocardiography. EF increased to 70% after 3 courses of chemotherapy with CHOP regimen. All lesions disappeared after 6 courses of chemotherapy were completed. After consolidative radiotherapy with a total dose of 37 Gy to the mediastinum and heart, bilateral pleural effusions, elevation of the patient's lactate dehydrogenase level and soluble IL-2 receptor value were recognized, which suggested relapse of the lymphoma, although histopathological confirmation could not be realized.

Aged↗