Search PubMed⌕ Search

Biomedical subjects

K Nagata

Publications and source records attributed to K Nagata.

At least 739 records · Page 41Linked to original sources
PubMed1990

Estradiol metabolism by complementary deoxyribonucleic acid-expressed human cytochrome P450s.

Twelve forms of human cytochrome P450 were synthesized in human hepatoma Hep G2 cells by means of cDNA-directed expression using vaccinia virus. The cDNA-expressed enzymes were tested for their ability to oxidize estradiol. Incubation of [14C]estradiol with cell lysates containing P450 IA2 resulted in the production of 2-hydroxy and 4-hydroxy metabolites with substrate turnovers of 2.74 and 0.27 min-1, respectively. P450s IIIA3 and IIIA4 yielded the same metabolites at about one third the rate of P450 IA2. Low levels of estradiol hydroxylation were also catalyzed by P450s IIC9, IIIA5, and IVB1. Six other P450 forms yielded no detectable metabolism. The roles of P450s IA2, IIA3, and IIIA4 were further established by immunoinhibition using antirat P450 antibodies. Antibody that specifically binds to P450 IIIA3 and IIIA4 inhibited 60-70% of estradiol hydroxylation, and antibody against P450 IA2 inhibited 20-40% of the estradiol hydroxylase activity in microsomes from two human liver specimens, suggesting that these enzymes constitute the major forms catalyzing estradiol oxidation in human liver. Immunoinhibition results also suggest that 2-hydroxy- and/or 4-hydroxycatechol estrogens are further metabolized to other yet uncharacterized metabolites by P450s IIIA3 and IIIA4.

Antibodies↗
PubMed1990

Efficacy and safety of catheter electrical ablation for ventricular tachycardia--experimental and clinical studies.

We studied the factors determining the extent of myocardial damage induced by catheter electrical ablation in 23 mongrel dogs and evaluated the efficacy and safety of catheter electrical ablation in 6 patients with medically refractory ventricular tachycardias (VT). Electrical shocks were delivered on the epicardium (EPI) and endocardium (END) of the ventricular wall of open-chest anesthetized dogs through a 6F USCI electrode catheter. Effect of the extent of electrode contact pressure was examined by the presence or absence of monophasic action potential using the contact electrode technique. The former was defined as the hard touch condition and the latter was defined as the soft touch condition. The myocardial lesion induced by EPI fulguration was larger than that by END fulguration (EPI-100 J soft touch: 10.2 +/- 2.9 mm in diameter, 6.6 +/- 1.6 mm in depth vs END-100 J soft touch: 7.7 +/- 1.7 mm in diameter, 5.0 +/- 1.2 mm in depth; p less than 0.05, p less than 0.05). The lesion diameter and lesion depth were enlarged by increasing the amount of delivered energy. The lesion depth by the hard touch condition was significantly greater than by the soft touch condition. The transmural perforation was observed in all EPI fulguration in the hard touch condition of the right ventricular wall. In the clinical study, one to three shocks (mean 1.8 +/- 0.7) of 60 to 200 J (mean 151 +/- 48 J) were delivered per session in 6 patients with medically refractory VT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

The role of alpha 1- and alpha 2-adrenoceptors in canine systemic capacitance vessels--a study with measurement of mean circulatory pressure.

We investigated the presence of alpha-adrenoceptor subtypes in systemic capacitance vessels by examining the effects of alpha 1- and alpha 2-agonists or antagonists on the mean circulatory pressure (MCP). Dogs were anesthetized with pentobarbital, and after total spinal anesthesia, epinephrine was given intravenously to maintain mean blood pressure at about 80 mmHg. 1. With intravenous injection of phenylephrine (alpha 1-agonist, 10 micrograms/kg, n = 7), and of BHT 920 (alpha 2-agonist, 5 micrograms/kg, n = 7), MCP increased significantly from 9.8 +/- 0.4 (mean +/- SE) to 10.9 +/- 0.3 mmHg (+11.2%, p less than 0.01), and from 9.3 +/- 0.4 to 10.3 +/- 0.4 mmHg (+10.8%, p less than 0.05), respectively. 2. Intravenous injection of prazosin (alpha 1-antagonist, 150 micrograms/kg, n = 7) and of yohimbine (alpha 2-antagonist, 30 micrograms/kg, n = 7) decreased MCP significantly from 9.9 +/- 0.4 to 8.2 +/- 0.5 mmHg (-17.2%, p less than 0.01), and from 9.8 +/- 0.2 to 7.6 +/- 0.3 mmHg (-22.4%, p less than 0.01), respectively. 3. Intravenous injection of phenylephrine (10 micrograms/kg, n = 7) after pretreatment with prazosin (150 micrograms/kg) decreased MCP significantly from 9.5 +/- 0.3 to 7.8 +/- 0.3 mmHg (-17.9%, p less than 0.01). MCP decreased significantly from 9.9 +/- 0.3 to 8.2 +/- 0.3 mmHg (-17.2%, p less than 0.01) after intravenous injection of BHT 920 (5 micrograms/kg, n = 7) following pretreatment with yohimbine (30 micrograms/kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Agonists↗
PubMed1990

Deficiency of beta-adrenoceptor-mediated relaxation in suncus trachea.

Characteristics of beta-adrenoceptor in the tracheal smooth muscle of Suncus murinus (suncus) were studied in comparison with those of rats and guinea pigs. Isoproterenol induced concentration-dependent relaxation of suncus trachea. However, the maximal relaxation was very small, and about 1000 times higher concentration was necessary compared to the case of the guinea pig. The order of the sensitivity to isoproterenol and the maximal relaxation was guinea pig much greater than rat greater than suncus. Tracheae from younger suncus were more sensitive to isoproterenol, but the maximal relaxation was not significantly different from the results using adult animals. Forskolin, a direct activator of adenylate cyclase, relaxed tracheae to similar extents in the three species. Though the affinity of specific [3H]dihydroalprenolol binding was not significantly different, the maximal number of binding sites was in the order of rat greater than guinea pig greater than suncus. However, the differences in density of the binding among the three species were not as great as differences in isoproterenol-induced relaxation. These results suggest that 1) beta-adrenoceptor-mediated relaxation of tracheal smooth muscle is not well-developed in the suncus and 2) the deficient relaxation is probably caused by insufficient coupling between adrenoceptors and adenylate cyclase.

Animals↗
PubMed1990

Occipital lobe infarction and positron emission tomography.

Even though the PET study revealed a total infarct in the territory of the left PCA in our 3 cases of pure alexia, it is still obscure which part of the left occipital lobe is most closely associated with the occurrence of the pure alexia. In order to elucidate the intralobar localization of the pure alexia, it is needed to have an ideal case who shows an pure alexia due to the localized lesion within the left occipital lobe. Furthermore, high-resolution PET scanner will circumvent the problem in detecting the metabolism and blood flow in the corpus callosum which plays an important role in the pathogenesis. We have shown that the occlusion of the right PCA also produced a left unilateral agnosia which is one of the common neurological signs in the right MCA infarction. To tell whether the responsible lesion for the unilateral spatial agnosia differs between the PCA occlusion and the MCA occlusion, the correlation study should be carried out in a greater number of the subjects. Two distinctive neuropsychological manifestations, cerebral color blindness and prosopagnosia, have been considered to be produced by the bilateral occipital lesion. The PET studies disclosed reduction of blood flow and oxygen metabolism in both occipital lobes in our particular patient who exhibited cerebral color blindness and prosopagnosia.

Aged↗
PubMed1990

Bacillus stearothermophilus glyceraldehyde-3-phosphate dehydrogenase as a source of angiotensin-converting enzyme inhibitors.

The more potent inhibitory activity against angiotensin-converting enzyme (ACE) was excised from a glyceraldehyde-3-phosphate dehydrogenase (GAPDH) preparation of Bacillus stearothermophilus by heating at 120 degrees C in 1 M AcOH-20 mM HCl, as compared with GAPDH preparations of yeast and pig. Sufficient excision of B. stearothermophilus ACE inhibitors required a longer proteolysis time of 60 min. Two inhibitors were then purified by gel-permeation and reverse-phase chromatographies. One of the B. stearothermophilus ACE inhibitors BG-1, was the GAPDH peptide 68-77 (Gly-Lys-Glu-Ile-Ile-Val-Lys-Ala-Glu-Arg, IC50: 32 microM). Another inhibitor, BG-2 (Gly-Lys-Met-Val-Lys-Val-Val-Ser-Trp-Tyr, IC50: 6 microM), correspond to GAPDH peptide 304-313. These sequences were quite different from those of vertebrate GAPDH peptides and the venom peptide family with ACE inhibitory activity. BG-2 was found to be a non-competitive type inhibitor, differing from many natural peptide inhibitors. Thus, B. stearothermophilus GAPDH seemed to be a good source of new type ACE inhibitors, in addition to the advantages due to its thermophilic property.

Amino Acid Sequence↗
PubMed1990

Role of humoral and cellular factors on the growth of blast progenitors of acute myeloblastic leukemia in serum-free culture.

To determine the growth requirement of leukemic blast progenitors in acute myeloblastic leukemia (AML), leukemic cells from the peripheral blood of eight AML patients were cultured in the serum-free culture system. Blast progenitors made colonies in methylcellulose culture and showed exponential growth in suspension culture, although the growth of blast progenitors in the absence of fetal calf serum (FCS) in some patients was inferior to that in the FCS-enhanced culture system. Recombinant human granulocyte colony-stimulating factor (rhG-CSF) stimulated the growth of blast progenitors in a dose-responsive manner. When cells were cultured at high cell density, blast colonies were formed even in the absence of CSF. Irradiated blasts also supported the growth of intact blast progenitors. These results confirm the finding noted in the FCS-enhanced culture studies that granulopoietic factor, G-CSF, plays an important role on the leukemic growth. The importance of cell to cell interaction for the growth of blast progenitors was also confirmed.

Blast Crisis↗
PubMed1990

Terminal differentiation to mature neutrophils and eosinophils in suspension culture of the blast progenitors in acute myeloblastic leukemia.

The blasts obtained from three freshly diagnosed acute myeloblastic leukemia (AML) patients were cultured in suspension to determine whether leukemic blast progenitors can indeed differentiate to form mature granulocytes. One patient was AML M2. The other two patients were bilineal and biphenotypic leukemia, respectively. Media conditioned by human bladder carcinoma line 5637 (5637-CM) or recombinant human granulocyte colony-stimulating factor (rhG-CSF) was added to stimulate growth. In suspension, clonogenic cells grew for 1-3 weeks in two patients, while they did not increase in one patient. After repeated subculture, cells of blast morphology decreased in percentage and polymorphonuclear neutrophils, eosinophils, and monocyte-macrophages appeared. Lymphoid cell component of the patient 2, who was diagnosed as bilineal leukemia by dual-color immunofluorescence analysis, decreased in number after suspension culture and cells of myeloid phenotype became dominant. The findings show that clonogenic blast progenitors can renew themselves and can also undergo terminal differentiation to mature end cells.

Adult↗
PubMed1990

Production and some properties of monoclonal antibodies against human pancreatic secretory trypsin inhibitor.

Hybridomas that secrete monoclonal antibodies against human pancreatic secretory trypsin inhibitor (PSTI) were established by fusion of spleen cells obtained from mice immunized with PSTI with mouse NS-I-Ag 4/1 myeloma cells. One of three resulting monoclonal antibodies (KN-1) was found to recognize the N-terminal moiety of the inhibitor, while the others (KN-2 and KN-3) reacted with other as yet undefined parts of the molecule. Trypsin inhibitory activity of PSTI treated with KN-1 monoclonal antibody was the same as that of PSTI itself, thus indicating no relationship between the N-terminal moiety of the PSTI molecule and its inhibitory activity. We further examined the applicability of one of the monoclonal antibodies (KN-1) for immunohistochemical study of human pancreatic cancer tissue including the normal as a model, and found granular staining of the cytoplasm of the normal acinar and duct cells and also of that of adenocarcinoma cells in formalin-fixed, paraffin-embedded tissue sections.

Adenocarcinoma↗
PubMed1990

Haematopoietic suppressing activity of gamma-interferon in serum and bone marrow of aplastic anaemia patients.

To determine the mechanism by which haematopoiesis is suppressed in aplastic anaemia, the effect of the sera from 6 patients on the granulopoietic precursors (colony-forming units in culture; CFU-C) was studied in vitro. Addition of the sera from 2 patients significantly suppressed CFU-C. The suppressive effect of the sera on CFU-C was inhibited by the addition of 1.5 NU/ml of anti-gamma-IFN antibody. In another patient, anti-gamma-IFN antibody increased autologous CFU-C although the serum of the patient did not suppress CFU-C. Serum gamma-IFN levels of all patients were under 2 IU/ml. The above findings suggest that humoral factors inhibit haematopoiesis in some patients with aplastic anaemia, and that gamma-IFN plays a role as an inhibitor even at a low concentration.

Adolescent↗
PubMed1990

[Molecular cloning and expression of Mycobacterium tuberculosis Aoyama B peptide antigen genes in Escherichia coli--a gene encoding 60 kD antigen (AT201) and immunological activity of recombinant peptides (15 and 60 kD)].

To obtain recombinant peptides related to PPDs, we constructed a genomic library from the DNA of Mycobacterium tuberculosis Aoyama B, a standard strain in Japan to manufacture PPDs, using plasmid vectors pUC18 series. Seven clones reacting the anti-PPDs-rabbit-serum on immunoblotting were obtained, and restriction map was analysed. A nucleotide sequence and a putative open reading frame (ORF) of pAT01, encoding 15kD peptide, as well as the mode of expression was reported previously). In this study, nucleotide sequence of 60 kD peptide gene was determined, and the comparative database analysis (GENBANK) revealed a striking level of homology to so called mycobacterial heat shock protein. The expression mode of pAT201 encoding 60 kD, as well as pAT01 encoding 15 kD peptide, indicated that these peptides were not hybrid proteins with the lacZ gene product, but they were consisted of peptides only mycobacterial source. Therefore, 15 kD and 60 kD directly were subjected to immunological studies. The peptides were extracted from E. coli, carrying pAT01 or pAT201, purified through series of DEAE chromatography and followed by Detoxi-Gel to remove LPS. 15 kD peptide behaved almost similar to PPDs both in the DTH skin reaction and the lymphocyte proliferation response on guinea pigs or rats in respect to sensitivity. However, 60 kD was unique in that, and it behaved like a general mitogen. We discussed role of 60 kD peptide, comparing with the common antigen, generally found in most species of bacteria as the heat shock protein.

Antigens, Bacterial↗
PubMed1990

Urban growth and health in Nagasaki after the atomic air raid.

According to development of the city, it has been revealed that demographic characteristics and living condition, as well as health status, have been differentiated among areas within it. On the causal relationships between urban growth and health, the present study shows no evidence, but a significant correlation between population density and demographic characteristics, and health, especially in maternal child health, have been observed in the same city (Takemoto et al., 1988). Considering the regionalization of characteristics in man and his environment within a city, public health activities based on the assessment of health needs in each community should be developed in urbanized society.

Demography↗
PubMed1990

Acetyltransferase and sulfotransferase which activate mutagens and carcinogens through O-esterification mechanisms.

The regulatory mechanism of acetyltransferase and sulfotransferase, which are involved in the activation of carcinogenic arylamines and their N-hydroxy derivatives, has been studied. Cytosolic N-acetylation of 2-aminofluorene (2-AF) in hamster liver and skin showed tri-modal distribution in the presence of acetyl CoA, whereas no clear segregation was detected in the N-hydroxyarylacetamide-supported N-acetylation and acetyl CoA-dependent O-acetylation of N-hydroxy-Glu-P-1. From hamster livers, two forms of acetyltransferase, AT-I and AT-II, were purified and characterized to have different catalytic and chemical properties. AT-I was detectable in all the hamsters examined, but AT-II was detected only in the animals showing high rates of 2-AF N-acetylation. Cross-matings of the intra- and inter-phenotypes of three different acetylators (rapid, intermediate, and slow) indicate the genetic inheritance of the arylamine N-acetylation, which follows a Mendelian co-dominant trait. Cytosolic sulfotransferase catalyzes the activation of N-hydroxyarylamines and N-hydroxyarylacetamides through the enzymatic O-sulfonylation. The reaction often shows a sex-related difference in rats. Among three sulfotransferases isolated (HAST I, II, and PST I), the level of HASTs was correlated with the 3'-phosphoadenosine 5'-phosphosulfate (PAPS)-dependent activating capacity of N-hydroxy-2-acetylaminofluorene (N-hydroxy-AAF) in rat livers. In addition, hepatic content of HASTs was decreased by hypophysectomy and restored by the intermittent administration of growth hormone, which mimics the male secretory profile. These results indicate that the sex-related difference in secretory profile of pituitary growth hormone is a major determinant of the male-dominant sulfation in this species.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Acetylaminofluorene↗
PubMed1990

[Acute myeloblastic leukemia and hepatocellular carcinoma following Waldenström's macroglobulinemia].

A 54-year-old man was admitted to our hospital for precise examination of pancytopenia in October 1988. He had been cut off his left femur and irradiated because of osteosarcoma in 1954. After 30 years, he was diagnosed as Waldenström's macroglobulinemia. Melphalan had been given 2 mg daily for 19 months until August 1988, when it was discontinued due to pancytopenia. Peripheral blood showed Hb 6.6 g/dl, platelet 40 x 10(3)/microliters, and WBC 2000/microliters with 33% blasts. Bone marrow showed normocellularity with 36% blasts. Although blasts were negative for peroxidase staining, surface marker analysis revealed myeloid (CD 13, CD 33) phenotypes. Chromosome analysis showed 45, XY, -7, inv (3). A CT scan of the liver showed a mass, 10 by 10 cm, compatible with hepatocellular carcinoma. He was treated with very low dose Ara-C without noticeable effect. Hepatic tumor gradually enlarged, and he died of hepatic failure. This is a rare case of quadruplicate malignancies. The chromosomal abnormality suggests that AML was secondary leukemia which might be associated with immunosuppression due to macroglobulinemia and/or melphalan therapy.

Carcinoma, Hepatocellular↗
PubMed1990

Another mechanism for the defect in type III collagen accumulation in Ehlers-Danlos syndrome type IV: increased intracellular degradation of the procollagen.

The nature of type III collagen was examined in the skin and cultured skin fibroblasts from a patient with Ehlers-Danlos syndrome type IV. Although the culture medium contained a much lower amount of Type III collagen than the controls, the cells contained an apparently normal amount of Type III collagen. The patient's Type III procollagen showed no abnormalities in apparent molecular weight, the peptide length as examined by cyanogen bromide cleavage, the genomic DNA size including its C- and N-propeptide portion, mRNA size, or thermal stability; but a pulse-chase study revealed prolonged retention of the type III collagen in the cells. Degradation of Type III procollagen was induced by cell extracts but did not occur in the extracellular space and was inhibited in intact cells by the addition of ammonium chloride or leupeptin to the culture medium. Fluorescent staining showed a characteristic granular deposition of Type III procollagen in the peripheral region of the cytoplasm but no granular deposition of Type I procollagen. These results offer new insight into the mechanism of the decreased amount of Type III collagen in the tissue of patients with Ehlers-Danlos syndrome type IV.

Ammonium Chloride↗
PubMed1990

[Weekly CHOP chemotherapy in the treatment of intermediate-grade non-Hodgkin's lymphomas--cooperative group study by seven institutes].

Between 1985 and 1988, 49 previously untreated patients with intermediate-grade non-Hodgkin's lymphoma (LSG classification large cell 35 including 11 large cell immunoblastic by Working Formulation, medium-sized cell 7, mixed 7) were treated with the Weekly CHOP regimen (three successive weekly administration of cyclophosphamide, doxorubicin, vincristine and prednisolone) as a cooperative group study by seven institutes (Nagoya Lymphoma Study Group). Complete remission was achieved in 63.3% with Weekly CHOP alone and finally in 79.6% after the addition of radiotherapy and/or combination chemotherapies including etoposide, methotrexate, procarbazine, bleomycin. Patients with T cell phenotype, high grade PS and the presence of bulky mass had significantly lower rates of CR. After a median follow-up 36 months Kaplan-Meier estimates showed that overall survival was 60.4%, disease-free survival 51.4% and relapse-free survival 64.6%. The major toxicities were alopecia, leukopenia, infection, neuropathy and gastrointestinal symptoms. No treatment-related deaths were observed. Survival was adversely affected by high LDH level, poor PS, T cell phenotype, the presence of B symptoms and the bulky mass. But these characteristics gave no significant effects on relapse rate and relapse-free survival. Thus, Weekly CHOP is an effective treatment for intermediate-grade NHL.

Adolescent↗