Search PubMed⌕ Search

Biomedical subjects

K Izawa

Publications and source records attributed to K Izawa.

At least 37 records · Page 2Linked to original sources
PubMed2000

Dejerine-sottas disease with a novel de novo dominant mutation, Ser 149 Arg, of the peripheral myelin protein 22.

The Ser149Arg mutation of peripheral myelin protein 22 (PMP22) was found in a 19-year-old woman with a sporadic case of Dejerine-Sottas disease. The patient showed delayed motor development. She walked for the first time with support at the age of 2 years. Scoliosis developed at age 4 years. Her walking ability was best at age 11. Thereafter, she showed progressive muscle weakness and sensory disturbances in the distal extremities. At the age of 18 years, the use of a wheelchair became necessary. Motor and sensory nerve conduction studies showed absent motor and sensory responses on electrical stimulation of the limb nerves. A sural nerve biopsy specimen showed marked decreases in the numbers of both large and small myelinated fibers, abundant onion-bulb formation, and hypomyelination. Electron microscopic observation revealed the presence of demyelinated axons and myelin sheaths disproportionately thin relative to axon diameter. That this was a de novo mutation was established by parentage testing and PMP22 gene analysis of the parents. The mutation seems to be novel and dominant.

Adult↗
PubMed2000

MHC (major histocompatibility complex)-DRB genes and polymorphisms in common marmoset.

A New World monkey, the common marmoset (Callithrix jacchus), will be used as a preclinical animal model to study the feasibility of cell and gene therapy targeting immunological and hematological disorders. For elucidating the immunogenetic background of common marmoset to further studies, in the present study, polymorphisms of MHC-DRB genes in this species were examined. Twenty-one Caja-DRB exon 2 alleles, including seven new ones, were detected by means of subcloning and the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) methods followed by nucleotide sequencing. Based on the alignment of these allele sequences, we designed two pairs of specific primers and established a PCR-SSCP method for DNA-based histocompatibility typing of the common marmoset. According to the family segregation data and phylogenetic analyses, we presumed that Caja-DRB alleles could be classified into five different loci. Southern blotting analysis also supported the existence of multiple DRB loci. The patterns of nucleotide substitutions suggests that positive selection operates in the antigen-recognition sites of Caja-DRB genes.

Alleles↗
PubMed2000

Binding of cell type-specific nuclear proteins to the 5'-flanking region of maize C4 phosphoenolpyruvate carboxylase gene confers its differential transcription in mesophyll cells.

C4-type phosphenolpyruvate carboxylase (C4PEPC) acts as a primary carbon assimilatory enzyme in the C4 photosynthetic pathway. The maize C4PEPC gene (C4Ppc1) is specifically expressed in mesophyll cells (MC) of light-grown leaves, but the molecular mechanism responsible for its cell type-specific expression has not been characterized. In this study, we introduced a chimeric maize C4Ppc1 5'-flanking region/beta-glucuronidase (GUS) gene into maize plants by Agrobacterium-mediated transformation. Activity assay and histochemical staining showed that GUS is almost exclusively localized in leaf MC of transgenic maize plants. This observation suggests that the introduced 5' region of maize C4Ppc1 contains the necessary cis element(s) for its specific expression in MC. Next, we investigated whether the 5' region of the maize gene interacts with nuclear proteins in a cell type-specific manner. By gel shift assays with nuclear extracts prepared from MC or bundle sheath cells (BSC), cell type-specific DNA-protein interactions were detected: nuclear factors PEP(Ib) and PEP(Ic) are specific to MC whereas PEP(Ia) and PEP(IIa) are specific to BSC. Light alters the binding activity of these factors. These interactions were not detected in the assay with nuclear extract prepared from root, or competed out by oligonucleotides corresponding to the binding sites for the maize nuclear protein, PEP-I, which is known to bind specifically to the promoter region of C4Ppc1. The results suggest that novel cell type-specific positive and negative nuclear factors bind to the maize C4Ppc1 5'-flanking region and regulate its differential transcription in MC in a light-dependent manner.

Binding Sites↗
PubMed2000

The promoter for the maize C4 pyruvate, orthophosphate dikinase gene directs cell- and tissue-specific transcription in transgenic maize plants.

The pyruvate,orthophosphate dikinase (PPDK) gene coding the chloroplast enzyme involved in C4 photosynthesis has a dual promoter system. The first promoter is responsible for the transcription of a larger transcript and its product is targeted to the chloroplast (hence, it is designated as C4Pdk promoter) while the second promoter is responsible for the transcription of a smaller transcript and its product remains in the cytosol. In this study, chimeric maize C4Pdk promoter (0.9 or 1.5 kb)-beta-glucuronidase or luciferase fusion genes were introduced into maize plants by Agrobacterium-mediated transformation. The cell- and tissue-specificities of the maize C4Pdk promoter in the transgenic maize plants were examined by histochemical and enzymic activity analyses of the reporters in different photosynthetic cells and tissues. The results showed that the reporter proteins are almost exclusively localized in leaf mesophyll cells. Among the tissues tested, leaf blade had the highest reporter activities with sheath exhibiting about 10% of the activities in blade. Husk, stem, tassel and root had no or very little reporter activities. Taken together, these results suggest that the maize C4Pdk promoter is specifically transcribed in the mesophyll cells of leaf blade and to a much less extent in the mesophyll cells of sheath, but not in leaf bundle sheath cells or other tissues. Furthermore, the 0.9 kb maize C4Pdk promoter sequences appear to contain the necessary cis-acting elements for its cell- and organ-specific expression.

Gene Expression Regulation, Enzymologic↗
PubMed1999

Modified Caspari technique for traumatic anterior shoulder instability: comparison of absorbable sutures versus absorbable plus nonabsorbable sutures.

The efficacy of the Caspari technique using a combination of absorbable and nonabsorbable sutures was compared with that of using only absorbable sutures. Forty-four patients (45 shoulders) underwent our modified Caspari technique for traumatic anterior shoulder instability and were followed-up for 2 to 3 years postoperatively. The average age at operation was 22 years. Among 27 patients treated using all absorbable PDS sutures, 7 patients had recurrent instability (success rate, 74%). Among 18 patients treated using both PDS and nonabsorbable polypropylene sutures, only one showed apprehension after a direct blow to the shoulder sustained by falling from a height (success rate, 94%). The mean stability score according to Rowe's criteria was significantly higher in the combination of absorbable and nonabsorbable group (P = .0412). External rotation increased more slowly in the combination of absorbable and nonabsorbable group than in the absorbable group. The mean limitation of external rotation was 8.4 degrees and 2.7 degrees, respectively (P = .0129). The modified Caspari technique using both absorbable and nonabsorbable sutures achieved excellent stability according to Rowe's criteria and external rotation showed more gradual improvement compared to repair with absorbable sutures alone.

Absorbable Implants↗
PubMed1998

Vaccine effect of granulocyte-macrophage colony-stimulating factor or CD80 gene-transduced murine hematopoietic tumor cells and their cooperative enhancement of antitumor immunity.

To develop immunogene therapy targeting minimal residual hematopoietic tumor cells in patients, we transduced murine GM-CSF or CD80 gene into murine WEHI 3B myelomonocytic leukemia and EL-4 thymic lymphoma cells using retroviral vectors and evaluated their effects on inducing antitumor responses in syngeneic host mice. Subcutaneously injected GM-CSF- and CD80 gene-transduced WEHI 3B (GMCSF/WEHI/3.2 or CD80/WEHI/1.8, respectively) cells lost their original tumorigenicity in immunocompetent syngeneic mice. Results from tumor inoculation experiments using athymic nude mice suggested that the rejection of GMCSF/WEHI/3.2 in immunocompetent mice depended fully on T cells and that of CD80/WEHI 1.8 depended partly on T cells and partly on NK cells. In both WEHI 3B and EL-4 models, irradiated GM-CSF gene-transduced cells provided strong immuno-protection against wild-type cells, but irradiated CD80 gene-transduced cells did not. A remarkably high cooperative effect was obtained when irradiated GMCSF/EL-4 and CD80/EL-4 were inoculated together. These results suggested that the tumor vaccine effect is efficiently enhanced by GM-CSF gene transduction and CD80 gene transduction induces some protective antitumor immunity in co-operation with GM-CSF gene transduction.

Animals↗
PubMed1998

[Differentiation between benign and malignant breast lesions using fat-suppressed dynamic MR imaging].

PURPOSE: To assess the value and problems of fat-suppressed dynamic MR imaging in differentiating between benign and malignant lesions. MATERIALS AND METHODS: In twenty-nine patients who underwent excisional biopsy or surgical resection, fat-suppressed dynamic MR imaging was performed with a 0.5 T superconducting magnet. Pre-and postcontrast 3D-spoiled gradient echo sequences were employed with fat suppression. We calculated and evaluated the contrast-to-noise ratio (CNR) and contrast enhancement ratio (CER) at each contrast determination time (CDT), which is the intermediate time in the scan. RESULTS: Time intensity curves of CNR showed no statistically significant difference between cancers and other benign lesions. The difference in CER between malignant and benign disease was highly significant (P = .006) at CDT 45 sec., but there was great overlap in the time intensity curve of CER after CDT 45 sec. CONCLUSION: When we attempt to differentiate malignant from benign breast lesions by dynamic MR imaging, comparison of CNR is impertinent, and we should evaluate the differential diagnosis of cancer versus benign lesions by means of CER at CDT points of about 45 sec.

Adolescent↗
PubMed1997

De novo mutation (Arg98-->Cys) of the myelin P0 gene and uncompaction of the major dense line of the myelin sheath in a severe variant of Charcot-Marie-Tooth disease type 1B.

A point mutation (Arg98-->Cys) of exon 3 coding for the extracellular domain of the myelin protein zero (P0) gene was found in a sporadic case of an eighteen year old Japanese man with a severe variant of Charcot-Marie-Tooth disease type 1B (CMT1B). A de novo mutation was established by parentage testing and analyses of the P0 gene in the family. This patient showed delayed motor development, nonprogressive limb weakness and kyphoscoliosis. In addition to the nerve biopsy findings typical of CMT1B, such as segmental demyelination, marked decrease in the density of myelinated fibers, and frequent onion-bulb formation, ultrastructural examination disclosed uncompaction of the major dense lines with slight widening of the intraperiod distance in the inner layers of the myelin sheath. Although mutations in the extracellular domain of P0 should affect homophilic adhesion between external surfaces of Schwann cell processes, resulting in the separation at the intraperiod lines, our study shows uncompacted major dense lines as a main myelin abnormality where the cytoplasmic domain of P0 resides.

Adolescent↗
PubMed1997

Correlation of clonal T cell expansion with disease activity in systemic lupus erythematosus.

It has been proposed that T cell activation may play an important role in the pathogenesis of systemic lupus erythematosus (SLE). In order to examine this hypothesis, we assessed the whole degree of clonal accumulation of T cells using RT-PCR and subsequent single-strand conformation polymorphism (SSCP) analysis. The analysis of the beta chain of the TCR revealed little clonotypic T cell expansion in the peripheral blood of lupus patients in remission, whereas in patients with active disease many dominant T cell clonal expansions without any distinct V beta bias were observed. The alteration in the number of T cell clones correlated well with disease activities, since these T cell expansions decreased as patients had improved. Furthermore, similar but more intense accumulations of T cell clones were found in pleural and pericardial effusions of patients with lupus serositis. Some of these identical expanded clonotypes were observed irrespective of the lesions and the times of sampling, and some of them were identical to those observed in the peripheral blood. These results suggest that the T cell clonal expansions correlate with the disease activities and that the expansion might contribute to the pathogenic lesion formation in SLE.

Adolescent↗
PubMed1996

Quantitation of a new potent angiotensin II receptor antagonist, TCV-116, and its metabolites in human serum and urine.

A sensitive high-performance liquid chromatographic (HPLC) method is described for the determination of a new potent antihypertensive agent, TCV-116, and its two metabolites (M-I and M-II) in human serum or urine. After pre-treatment of the specimens, the analytes were determined using a column switching technique, except for the metabolites in urine which were determined by gradient elution mode HPLC. The quantitation limits for TCV-116, M-I and M-II were all 0.5 ng/ml in serum, and 0.5, 10 and 110 ng/ml in urine, respectively. The methods were applied to clinical trials of TCV-116.

Angiotensin II↗
PubMed1996

Stable clonal expansion of T cells induced by bone marrow transplantation.

The immune mechanisms of T cells regeneration after bone marrow transplantation (BMT) and the factors maintaining allogeneic marrow graft in the host are still unknown. To pursue this issue, we analyzed T-cell clonality of peripheral blood lymphocytes (PBLs) in BMT recipients, using reverse transcription polymerase chain reaction with T-cell receptor (TCR) V beta gene segment-specific primers and single-strand conformation polymorphism. PBLs from patients and donors showed a heterogeneous T-cell population with oligoclonal accumulations of CD8+ T cells. When PBLs were cultured in HLA-matched mixed lymphocytes reaction in vitro, no distinct clonal expansion was observed. However, after BMT, oligoclonal expansions were induced in the recipients in vivo, without a restriction of TCR V beta gene usage. Although part of the expansion was transient, the majority was repeatedly detected even several months later. Our results suggested that certain in vivo mechanisms maintain a stable clonal expansion of distinct T cells in marrow recipients. We also found in a single patient with graft-versus-host disease a replacement of expanded clones by other clones during follow-up. Diminishing numbers of accumulation clones were found in long-term marrow recipients, indicating a general tendency for clonal expansion to subside progressively. Considered together, our data suggest the involvement of clonally expanded T cells in lymphoid regeneration and in acute and chronic immune responses after BMT.

Adolescent↗
PubMed1996

Mannosylated superoxide dismutase inhibits hepatic reperfusion injury in rats.

Superoxide anion radical (O2-) is one factor related to ischemia/reperfusion injury to the liver. The sites of O2- production and injury have yet to be determined. Superoxide dismutase (SOD), a specific scavenger for O2-, has an inhibitory effect on injury caused by O2-. SOD is of low molecular weight; hence, it has a short half-life in the circulating blood. Mannosylated SOD is taken up in sinusoidal endothelial cells of the liver by receptor-mediated endocytosis. In rats with an occluded inflow against 70% of the liver for 30 min followed by reperfusion there were elevations of serum aspartate aminotransferase and alanine aminotransferase, and lipid peroxide concentrations in liver tissue were significantly inhibited by intravenous administration of mannosylated SOD compared to treatment with normal saline. Electron microscopic examination showed that mannosylated SOD protected against damage to the sinusoidal endothelial cells caused by ischemia/reperfusion and that conventional SOD had no such protective effect. Thus, O2- produced by ischemia/reperfusion apparently damages sinusoidal endothelial cells, and damage to hepatic parenchymal cells is secondary. Mannosylated SOD deserves further study for possible use in surgical resection of the liver and for liver transplantations.

Alanine Transaminase↗
PubMed1996

A simple and secure anchoring system for Caspari's transglenoid multiple suture technique using a biodegradable poly-l-lactic acid button.

To manage a difficulty in tying sutures over the infraspinatus fascia when using Caspari's transglenoid multiple suture technique, we developed a new anchoring system using a biodegradable poly-L-lactic acid (PLLA) button and investigated its clinical efficacy in 28 patients who were followed-up for more than 2 years postoperatively (mean, 26.5 months). Twenty-four patients had Bankart lesions and 4 had detachment of the superior glenoid labrum. The mean age at operation was 22.1 years. The PLLA button measured 8 x 8 x 1.2 mm and had two holes. After multiple sutures were inserted by the routine Caspari technique (mean, 7.3 sutures), the sutures were divided into 2 bundles, passed through the holes in the button, and tied over it on the posterior scapular neck under traction. The arm was immobilized in a Velpeau bandage for 3 weeks after Bankart repair and for 1 to 2 weeks after superior labral repair. The results of Bankart repair were excellent in 13 patients, good in 7, and poor in 4 according to Rowe's rating scale (success rate, 83%), while the outcome of superior labral repair was excellent in 3 and good in 1 according to our own criteria. All 4 patients who showed a poor outcome were contact athletes who developed resubluxation postoperatively. There were no complications, but transient damages to the suprascapular nerve occurred in 2 patients. In conclusion, the PLLA button provided simple and secure suture fixation for the Caspari technique.

Adolescent↗
PubMed1996

Isolation of 45 exon-like fragments from 8p22-->p21.3, a region that is commonly deleted in hepatocellular, colorectal, and non-small cell lung carcinomas.

The loss of heterozygosity that is frequently observed at chromosome 8p22-->p21.3 in hepatocellular carcinomas (HCC), colorectal cancers (CRC), prostate cancers (PRC). and non-small cell lung cancers (NSCLC), suggests the presence there of one or more tumor suppressor genes associated with development and/or progression of these types of carcinomas. We have constructed a cosmid contig map of the target region by means of Southern hybridization and have isolated 45 exon-like fragments by exon amplification, using cosmid clones derived from three yeast artificial chromosomes (YACs). The map and the exon-like fragments reported here will be useful resources for isolation of the putative tumor suppressor gene(s) as well as other novel genes located in the 8p22-->p21.3 region.

Amino Acid Sequence↗
PubMed1995

Suppression of pulmonary metastasis by angiogenesis inhibitor TNP-470 in murine osteosarcoma.

We treated a murine osteosarcoma cell line, LM8, which preferentially metastasizes to the lungs, with a new angiogenesis inhibitor, TNP-470, to evaluate the efficacy of this compound in the suppression of pulmonary metastasis of osteosarcoma. In an in vivo experiment, tumor cells were inoculated i.v. into C3H mice, and TNP-470 or vehicle alone (control group) was administered s.c. every day for 3 weeks. In the TNP-470-treated groups, both the number of pulmonary metastatic nodules and the lung wet weight were significantly reduced in a dose-dependent manner. Similarly, vascular density in the metastatic tumors estimated by immunohistochemical staining with anti-von-Willebrand factor antibody as an endothelial marker were significantly reduced. No severe side-effects were found. In an in vitro experiment, viable tumor cells were counted after 3 days' treatment with TNP-470. The 50% inhibitory concentration was 0.6 ng/ml for LM8, which was more sensitive than other tumor cells previously reported. Our results show that TNP-470 suppresses the pulmonary metastasis of LM8 and suggest that both its anti-angiogenic activity and cytostatic activity towards LM8 are responsible for the antitumor effect.

Animals↗