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Biomedical subjects

H Iwata

Publications and source records attributed to H Iwata.

At least 163 records · Page 9Linked to original sources
PubMed2000

The complete nucleotide sequence of segment L2 of Ibaraki virus encoding for the antigen recognized by neutralizing antibodies.

The complete nucleotide sequence of cDNA clones representing the L2 dsRNA from Japan isolate of epizootic hemorrhagic disease serotype 2 (EHDV-2JPN) was determined. The EHDV-2JPN L2 gene is 3002 base pairs long with a single open reading frame of 2949 bp which predicts a polypeptide of 982 amino acid residues. Comparison of VP2 sequence between Japan and North American Isolates of EHDV-2 showed a 72% homology in spite of the same serotype, although those among the North American isolates showed a high genetic identity (>97%).

Animals↗
PubMed2000

Effects of glucocorticoids on tumor necrosis factor alpha-dependent activation of nuclear factor kappaB and expression of the intercellular adhesion molecule 1 gene in osteoblast-like ROS17/2.8 cells.

Recently, we showed that tumor necrosis factor alpha (TNF-alpha) stimulates expression of the intercellular adhesion molecule 1 (ICAM-1) and interleukin-6 (IL-6) genes through activation of p65-p50 heterodimer nuclear factor KB (NF-kappaB) in rat osteoblast-like ROS17/2.8 cells. In the present study, we investigated effects of a synthetic glucocorticoid, dexamethasone (Dex), on TNF-alpha-dependent activation of NF-kappaB and expression of the ICAM-1 gene. ROS17/2.8 cells were pretreated with Dex for 6 h and then exposed to TNF-alpha. Electrophoretic mobility shift assay (EMSA) revealed that TNF-alpha-dependent activation of NF-kappaB was almost completely suppressed by Dex treatment. Increase in ICAM-1 messenger RNA (mRNA) level by TNF-alpha also was markedly suppressed by Dex. Western blot and immunocytochemical analyses showed that Dex attenuated the TNF-alpha-induced nuclear translocation of p65. Treatment with protein synthesis inhibitor cycloheximide (CHX) reversed the Dex effect, indicating that Dex requires de novo protein synthesis for its action. Northern blot analysis revealed that Dex increased IkappaB-alpha mRNA level synergistically with TNF-alpha, whereas it decreased p65 mRNA level. The p105 and IkappaB-beta mRNA levels were not altered by Dex. Consistent with the mRNA level, Dex increased the amount of IkappaB-alpha protein in the cytoplasm in either the presence or the absence of TNF-alpha. Considering a role of IkappaB to sequester NF-kappaB in the cytoplasm, it was suggested that an increase in IkappaB-alpha protein and the concomitant decrease in p65 synthesis account for the Dex-induced suppression of NF-kappaB activation in osteoblastic cells.

Animals↗
PubMed2000

Prognostic impact of telomerase activity in patients with neuroblastoma.

Neuroblastoma is one of the most common malignant neoplasms occurring among children. The prognosis for this disease is strongly associated with age, disease stage, histology, and some biologic features. It has been reported that telomerase, a ribonucleoprotein enzyme, which maintains the telomere length in immortal cells, is related to disease stage and other biologic features. The purpose of this study was to evaluate the prognostic value of telomerase activity compared to TrkA expression in 65 patients with neuroblastoma. Telomerase activity and TrkA expression were examined in tissue samples collected between 1980 and 1994 from 65 patients by polymerase chain reaction-based telomerase activity. TrkA expression was examined by immunoblotting using a rabbit anti-gp140 proto-trk polyclonal antibody. Low telomerase activity was found in 22 of 30 (73.3%) patients with Stages 1, 2, or 4S neuroblastomas; 7 of 13 (53.8%) with Stage 3; and 8 of 22 (36.3%) with stage 4; no telomerase activity was detected in 7 of 22 (31.8%) patients with Stage 4 neuroblastoma. The 5-year event-free survival (EFS) rate was 86.5% for patients with low telomerase activity, while it was 53.8% for patients with high telomerase activity. By the combination of telomerase activity and TrkA expression, the 5-year EFS rate was highest among patients with a high TrkA expression and a low or non-existent telomerase activity (91.7%), and it was lowest among patients with a low TrkA expression and a high telomerase activity (29.6%). Thus, it appears that telomerase activity would be a useful prognostic factor for neuroblastoma, especially when used in combination with the TrkA expression.

Adolescent↗
PubMed2000

[An elderly case of ruptured aortic arch aneurysm with hemorrhagic cardiac tamponade].

We reported a case of successful aortic arch replacement using selective cerebral perfusion for ruptured distal aortic arch aneurysm (DAAA) with cardiac tamponade. A 80-year-old man who had preoperative episode of severe chest pain. Computed tomography showed saccular DAAA and pericardial effusion. He was diagnosed as ruptured DAAA with hemorrhagic cardiac tamponade. We performed urgent graft replacement of the aortic arch using selective cerebral perfusion. Postoperatively he had no complication. Thirty days after the operation he was discharged from the hospital and he is now leading a normal life.

Aged↗
PubMed2000

A novel mutation of KCNQ3 (c.925T-->C) in a Japanese family with benign familial neonatal convulsions.

At present, only one mutation of KCNQ3, a KCNQ potassium channel gene, has been identified as a cause of benign familial neonatal convulsions type 2 (BFNC2). We found a T to C substitution (c.925T-C) on one allele of affected individuals in a Japanese family with BFNC but not on 200 alleles from healthy subjects. c.925T-->C replaced Trp309, a conserved residue within the P-loop of the KCNQ potassium channel family that holds the channel pore open, with an Arg (W309R). We report c.925T-->C as the second mutation of KCNQ3 responsible for BFNC2.

Amino Acid Sequence↗
PubMed2000

Genetic association between rheumatoid arthritis and estrogen receptor microsatellite polymorphism.

OBJECTIVE: To investigate estrogen receptor (ER) microsatellite allele frequencies in patients with rheumatoid arthritis (RA), and possible associations of ER microsatellites with osteoporosis and disease progression. METHODS: We typed 144 Japanese females with RA and 200 healthy postmenopausal Japanese controls for ER microsatellites by polymerase chain reaction methods using fluorescent labeled primer and semiautomatic genotyping. Bone mineral density (BMD) of patients was measured in the spine by dual energy x-ray absorptiometry, and recent radiographs of the hands and wrists were scored according to the method described by Sharp, et al. RESULTS: The ER genotype was classified according to number of dinucleotide (thymine-adenine, TA) repeats between 10 and 27. The frequency of allele 14 (14 repeats of TA) was significantly increased in patients versus controls. No association of ER microsatellites with osteoporosis or radiographic progression in the RA patients was noted. CONCLUSION: These results suggest that a genetic variation at the ER locus may be associated with other pathogenetic factors in patients with rheumatoid arthritis, but not with BMD and disease aggressiveness.

Adult↗
PubMed2000

Calcium phosphate crystal-associated proteins: alpha2-HS-glycoprotein, prothrombin F1, and osteopontin.

PURPOSE: To elucidate the process of urinary stone formation, many urinary constituents have been examined as inhibitors or promoters. MATERIALS AND METHODS: We analyzed specific binding proteins of calcium phosphate (CaP) crystals generated in human urine and found that the separated proteins were alpha2-HS-glycoprotein, prothrombin fragment 1 (PTF1), and osteopontin (OPN). We also studied their inhibitory effects on calcium oxalate crystallization and the quantitative differences in urinary excretion of the proteins in healthy individuals and stone formers. RESULTS: Both PTF1 and OPN had strong inhibitory effects on growth of calcium oxalate crystals. No differences in alpha2-HS-glycoprotein were found between healthy subjects and stone formers. Urinary concentrations of PTF1 and OPN were lower in stone formers than in healthy controls. No differences in these proteins were seen between single and recurrent stone formers. CONCLUSION: Low urinary concentrations of PTF1 and OPN might be one reason for stone formation.

Adolescent↗
PubMed1999

A novel mutation of CHRNA4 responsible for autosomal dominant nocturnal frontal lobe epilepsy.

OBJECTIVE: To identify the mutation responsible for autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) in a nonwhite family. BACKGROUND: ADNFLE is newly recognized as an entity of idiopathic partial epilepsy. Recently, two different mutations of the neuronal nicotinic acetylcholine receptor alpha4 subunit (CHRNA4) gene were identified in a white family as a cause of ADNFLE. METHODS: Four affected and three unaffected individuals in three generations of a Japanese family with ADNFLE, and 100 unrelated healthy Japanese volunteers were studied. Clinical features and EEG findings in affected individuals were consistent with those of ADNFLE reported in white families with ADNFLE. Mutations within the CHRNA4 gene were screened for using single-strand conformation polymorphism analysis (SSCA) and were determined by direct sequencing. The mutation identified was sought in volunteers by the amplification refractory mutation system. RESULTS: A C-to-T exchange (C755T) was found in exon 5 of the CHRNA4 gene on one allele of affected individuals. C755T segregated in affected individuals and was not found in 200 alleles obtained from the volunteers. C755T replaced serine 252 (Ser252) in the second membrane-spanning domain (M2) of CHRNA4 with a leucine. Ser252 is conserved characteristically in the alpha-subunit of acetylcholine receptor and is considered to play an important role in channel function. CONCLUSION: C755T is a novel missense mutation of the CHRNA4 gene causing autosomal dominant nocturnal frontal lobe epilepsy in this Japanese family.

Circadian Rhythm↗
PubMed1999

Identification of Cancer Antigens in Breast Cancer by the SEREX Expression Cloning Method.

Enormous strides in cancer immunology have been made during the past decade. This is largely due to the development of methodologies capable of defining the antigenic targets on cancer cells that elicit a host immune response. The molecular cloning of antigens recognized by cytotoxic T cells by Boon and his colleagues has provided a growing list of tumor antigens, particularly for melanoma, that allows detailed monitoring of T cell responses to these antigens and offers promising targets for cancer vaccine development. An alternative new method, SEREX, for the serological identification of cancer antigens has been developed by Pfreundschuh and his colleagues. SEREX can be applied to all types of cancer including breast cancer that have been unapproachable by using cytotoxic T cells and thus offers an opportunity to define a vast range of cancer antigens. Toward thedevelopment of a vaccine for breast cancer, we have begun using SEREX to study breast cancer and have identified a few promising cancer antigens. Each antigen is now being critically evaluated as a possible vaccine target.

Journal Article↗
PubMed1999

Clinical Significance of Estrogen Receptor Àin Breast Cancer.

To estimate the clinical significance of estrogen receptor (ER) beta in breast cancer we reviewed some reports and compared them with our preliminary results. The structure of ERbetais similar to that of ER alpha. The DNA binding domain of ER beta is 96% conserved compared with ER alpha, and the ligand binding domain shows 58% conserved residues, suggesting that both receptors can bind estrogen responsiveelements on target genes and that they may also bind similar ligand. The targettissues of ER beta such as testis, prostate, lung, brain, thymus, and ovary, are different from those of ER alpha, ovary, uterus, endometrium, and breast. Although the function of ER beta in breast cancer progression is not well understood, 30-50% of breast cancers may express ER beta mRNA signals. Additionally, ER beta may be auseful prognostic factor in patients with breast cancer, because tumors that co-expressed ER alpha and ER beta might be node positive and tend to be of higher grade.Further characterization of the function of ER beta and its isoforms in breast cancer is warranted.

Journal Article↗
PubMed1999

Chemoprevention of heterocyclic amine-induced carcinogenesis by phenolic compounds in rats.

Chemopreventive effects of synthetic and naturally occurring antioxidants on heterocyclic amine (HCA)-induced rat carcinogenesis and mechanisms of inhibition were assessed. In a medium-term liver bioassay, combined treatment with 0.03% 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and synthetic antioxidants such as 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), BHA, BHT, tert-butylhydroquinone (TBHQ) and propyl gallate, each at a dose of 0.25%, and troglitazone at doses 0.5 and 0.1%, potently inhibited development of glutathione S-transferase placental form (GST-P) positive foci as compared with MeIQx alone values. Of these antioxidants, HTHQ showed the greatest activity. Green tea catechins tended to inhibit GST-P positive foci development, while quercetin, rutin, curcumin, daidzin, ferulic acid and genistin all exerted significant enhancing effects. HTHQ also inhibited 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced colon carcinogenesis in a two stage colon carcinogenesis model using 1,2-dimethylhydrazine (DMH) as an initiator. Immunohistochemically detected PhIP-DNA adduct positive nuclei in the colon induced by continuous oral treatment with 0.02% PhIP for 2 weeks decreased by the combined treatment with 0.5 or 0.125% HTHQ. Methoxyresorfin O-demethylase activity in rat liver microsomes in vitro was clearly inhibited by the addition of HTHQ, BHA, BHT, TBHQ or propyl gallate, with particularly strong inhibition being observed in HTHQ. However, the CYP1A2 level in rat liver increased after oral treatment with HTHQ for 2 weeks. These results indicate that synthetic antioxidants, HTHQ in particular, is a very strong chemopreventor of HCA-induced carcinogenesis. It is suggested that depression of metabolic activation rather than antioxidant activity is responsible for the observed effect. However, other mechanisms, including the effects on phase II enzymes cannot be ruled out.

Animals↗
PubMed1999

Establishment of a Salmonella tester strain highly sensitive to mutagenic heterocylic amines.

A co-expression plasmid (p1A2OR) carrying human CYP1A2 and NADPH-P450 reductase cDNAs and an expression plasmid (pOAT) carrying Salmonella TA1538/ARO cells. The CYP and OAT expressed in the Salmonella cells showed catalytic activity. The TA1538/ARO strain exhibited high sensitivity to heterocyclic amines (HCAs) such as 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,8-dimenthylimidazo[4,5-f]quinoline (MeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) as compared with the parent Ames tester strain TA1538. It is suggested that the intracellular expression of drug-metabolising enzymes makes the Salmonella cells highly sensitive to the HCAs.

Catalysis↗
PubMed1999

Determining the site of the primary cancer in patients with skeletal metastasis of unknown origin: a retrospective study.

BACKGROUND: When skeletal metastasis is the presenting problem and the primary site is occult, there is a need to identify the primary site as soon as possible. However, the search for the primary tumor is often time-consuming and difficult. The purpose of this study was to analyze the efficacy of particular diagnostic approaches and to devise an efficient and optimal diagnostic strategy. METHODS: Among 213 patients with skeletal metastasis treated between 1990 and 1996 were 64 in whom skeletal lesions were the first manifestation of malignancy. The authors retrospectively analyzed both the final diagnosis and the process by which it was made in these 64 cases. RESULTS: The primary cancer was identified antemortem in 56 (88%) of the 64 patients by examination and in 3 patients at autopsy. Lung carcinoma, the most frequently observed primary lesion, was identified in 23 patients. Other primary lesions were prostate carcinoma in 11 patients, breast carcinoma in 5, and hepatocellular carcinoma in 5. The primary malignancy was not determined in 5 patients. Thoracic and abdominal computed tomography (CT) scans were useful, especially in the diagnosis of patients with lung, hepatocellular, renal cell, and pancreatic carcinomas. Tumor markers were abnormally elevated in 73% of patients with carcinomas. CONCLUSIONS: Although thoracic and abdominal CT scans were useful, examination of the gastrointestinal tract and pelvic CT scan seldom revealed the primary lesion and therefore should not be performed as an initial routine study in the absence of abdominal symptoms. Tumor markers are useful in differentiating carcinoma from hematologic malignancy and primary bone tumor.

Adult↗
PubMed1999

Evaluation of ammonia and lidocaine clearance, and galactose elimination capacity of xenoperfused pig livers using a pharmacokinetic analysis.

BACKGROUND: We introduced the pharmacokinetic method into the functional evaluation of xenogeneic extracorporeal liver perfusion as an artificial liver assist device, and examined the influence of xenogeneic humoral injury on the metabolic function of xenoperfused pig livers. METHODS: Isolated pig livers were perfused with fresh porcine blood (group 1; n=5) or fresh human blood (group 2; n=5) for 9 hr. Clearance (CL) of ammonia and lidocaine, and galactose elimination capacity (Vmax) were determined at three points during the perfusion using a one-compartment pharmacokinetic model. RESULTS: Concentrations of ammonia and lidocaine decreased exponentially and those of galactose decreased linearly after a bolus injection in both groups. A one-compartment model provided satisfactory curve fittings for these test substances. No decreases of ammonia CL, lidocaine CL, or galactose Vmax were observed until 9 hr in either group. No differences were observed between the two groups with respect to these metabolic functions. In group 1, only slight interlobular edema was observed at 9 hr. In group 2, membrane attack complex was diffusely deposited at 3 hr and severe interlobular damage was histologically observed at 9 hr, although hepatocellular damage was minimal even at 9 hr. Alpha glutathione S-transferase and mitochondrial aspartate aminotransferase were comparable between the two groups. CONCLUSIONS: Pharmacokinetic analysis allowed the evaluation of ammonia CL, lidocaine CL, and galactose Vmax of the perfused pig livers. Despite xenogeneic humoral injuries, the xenoperfused livers maintained these metabolic functions at the same levels as the alloperfused livers for 9 hr.

Ammonia↗
PubMed1999

Consecutively Occurring Multiple Fibroadenomas of the Breast Distinguished from Phyllodes Tumors by Clonality Analysis of Stromal Tissue.

We present a woman with consecutively occurring multiple fibroadenomas of thebreast distinguished from phyllodes tumor by clonality analysis of stromal tissue. Fifty-three masses developed in her right breast in an 11.5 year period since first onset. A clonality analysis, performed by polymerase chain reaction (PCR), focused on the Hpa II site within exon 1 of the androgen receptor (AR) gene. Estrogen receptor (ER) alpha immunohistochemistry was performed with a specific polyclonal antibody against the hormone binding domain of the protein. Since all of the nodules were polyclonal in stromal tissues, they were hyperplastic rather than true neoplasms such as phyllodes tumors. The co-existence of abundant adenosisfoci and numerous sub-clinical small nodules in the adjacent breast tissue alsosuggested proliferative stimuli throughout the breast. ER alpha protein was expressed only in the nuclei of epithelial cells. The possible influence of ER positive epithelial cells on stromal cell growth is discussed.

Journal Article↗