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Biomedical subjects

K Isono

Publications and source records attributed to K Isono.

At least 235 records · Page 13Linked to original sources
PubMed1992

Systematic sequencing of the Escherichia coli genome: analysis of the 0-2.4 min region.

A contiguous 111,402-nucleotide sequence corresponding to the 0 to 2.4 min region of the E. coli chromosome was determined as a first step to complete structural analysis of the genome. The resulting sequence was used to predict open reading frames and to search for sequence similarity against the PIR protein database. A number of novel genes were found whose predicted protein sequences showed significant homology with known proteins from various organisms, including several clusters of genes similar to those involved in fatty acid metabolism in bacteria (e.g., betT, baiF) and higher organisms, iron transport (sfuA, B, C) in Serratia marcescens, and symbiotic nitrogen fixation or electron transport (fixA, B, C, X) in Azorhizobium caulinodans. In addition, several genes and IS elements that had been mapped but not sequenced (e.g., leuA, B, C, D) were identified. We estimate that about 90 genes are represented in this region of the chromosome with little spacer.

Bacterial Proteins↗
PubMed1992

Physical dissection and characterization of chromosomes V and VIII of Saccharomyces cerevisiae.

Chromosomes V and VIII of S. cerevisiae were dissected and ordered clone banks were constructed and characterized. Each bank contains almost the entire chromosome from the left to the right telomere except for a small gap in each case. The size of the banks constructed is in good agreement with the physical length of these chromosomes, 580 kb, estimated by pulsed-field gel electrophoresis. The remaining gap in the ordered clone bank of chromosome V was found to be only 1.6 kb in length and to contain a 1.5 kb-long portion of one of the two Ty elements located in tandem. The gap in the bank of chromosome VIII was 6.4 kb in length and contained four copies of the CUP1 gene. A genomic restriction map analysis of the corresponding region of chromosome VIII revealed that a unit of about 2 kb in length harbouring the CUP1 gene was repeated ten times in strain DC5 rho degrees which was used for the bank construction. A 588.5 kb-long high resolution physical map for chromosome V and a 585.6 kb-long one for chromosome VIII have thus been established.

Bacteriophage lambda↗
PubMed1992

Isoflavonoids, genistein, psi-tectorigenin, and orobol, increase cytoplasmic free calcium in isolated rat hepatocytes.

Isoflavonoid compounds, genistein, psi-tectorigenin and orobol have been implicated as inhibitors of tyrosine-specific protein kinase and phosphatidylinositol turnover. These compounds have been frequently used as a pharmacological tool to assess signal transduction pathways in various cell systems. In the course of analyzing signaling pathways in rat hepatocytes, we obtained an unexpected finding that these compounds transiently increase cytoplasmic free calcium. Since the Ca2+ mobilizing effect was observed in 1 microM calcium containing buffer, the source of the Ca2+ may be intracellular stores. Thus, when interpreting data obtained using these compounds, caution is needed.

Aequorin↗
PubMed1992

Cell-cell interaction in graft rejection responses: induction of anti-allo-class I H-2 tolerance is prevented by immune responses against allo-class II H-2 antigens coexpressed on tolerogen.

The intravenous sensitization of C57BL/6 (B6) mice with class I H-2-disparate B6-C-H-2bm1 (bm1) spleen cells results in almost complete abrogation of anti-bm1 CD8+ helper (proliferative and interleukin 2-producing) T cell (Th) activities. Although an appreciable portion of CD8+ cytotoxic T lymphocyte (CTL) precursors themselves remained after this regimen, such a residual CTL activity was eliminated after the engrafting of bm1 grafts, and these grafts exhibited prolonged survival. In contrast, the intravenous sensitization with (bm1 x B6-C-H-2bm12 [bm12])F1 cells instead of bm1 cells failed to induce the prolongation of bm1 graft survival as well as bm12 and (bm1 x bm12)F1 graft survival. In the (bm1 x bm12)F1-presensitized B6 mice before as well as after the engrafting of bm1 grafts, anti-bm1 CTL responses that were comparable to or slightly stronger than those observed in unpresensitized mice were induced in the absence of anti-bm1 Th activities. bm1 graft survival was also prolonged by intravenous presensitization with a mixture of bm1 and bm12 cells but not with a mixture of bm1 and (bm1 x bm12)F1 cells. The capacity of CD4+ T cells to reject bm12 grafts was eliminated by intravenous presensitization with antigen-presenting cell (APC)-depleted bm12 spleen cells. However, intravenous presensitization with APC-depleted (bm1 x bm12)F1 cells failed to induce the prolongation of bm1 graft survival under conditions in which appreciably prolonged bm12 graft survival was induced. More surprisingly, bm1 graft survival was not prolonged even when the (bm1 x bm12)F1 cell presensitization was performed in CD4+ T cell-depleted B6 mice. This contrasted with the fact that conventional class I-disparate grafts capable of activating self Ia-restricted CD4+ as well as allo-class I-reactive CD8+ Th exhibited prolonged survival in CD4+ T cell-depleted, class I-disparate cell-presensitized mice. These results indicate that: (a) intravenous presensitization with class I- and II-disparate cells fails to reduce anti-allo-class I rejection responses that would otherwise be eliminated using only class I-disparate cells; (b) such failure is generated according to the coexpression of both classes of alloantigens on a single cell as tolerogen; and (c) allo-class II antigens coexpressed on tolerogen function to activate CD4+ as well as non-CD4+ Th leading to the generation of anti-class I effector T cell responses.

Animals↗
PubMed1992

p53 gene mutations in gastric and esophageal cancers.

The presence of point mutation of the p53 gene in exons 5, 6, 7, and 8 was examined in 10 cases of gastric adenocarcinoma and 5 cases of esophageal squamous cell carcinoma by polymerase chain reaction and direct nucleotide sequencing. Mutations of the p53 gene were found in 5 cases of gastric cancer and 4 cases of esophageal cancer. The mutations in the stomach cancers consisted of four missence mutations (exons 5 and 8) and one frame shift (exon 7). In the esophageal cancers, three missence mutations (exons 6, 7, and 8) and one point mutation within the splice donor site of intron 5 were found. Of the seven missence mutations in the two cancers, five showed the transition from G to A and two from G to T. All these changes occurred in the highly conserved region of the p53 protein. These results suggest that mutations of the p53 gene are genetic events in the pathogenesis of gastric adenocarcinoma and esophageal squamous cell carcinoma.

Adult↗
PubMed1992

Thromboxane A2 mimetic U46619 stimulates ciliary motility of rabbit tracheal epithelial cells.

To elucidate whether thromboxane A2 (TxA2), one of the important arachidonic acid metabolites that may play a role in the development of airway inflammation, affects respiratory ciliary motility and, if so, what the mechanism of action is, we measured ciliary beat frequency (CBF) of rabbit cultured tracheal epithelium in response to U46619, a TxA2 mimetic agonist, by a photoelectric method. Addition of U46619 (10(-5) M) increased CBF from 17.7 +/- 0.7 to 22.8 +/- 1.4 Hz (mean +/- SE, p less than 0.01) within 5 min, which was followed by a decline to the baseline value by 10 min. This effect was concentration-dependent, the maximal increase from the baseline value and the drug concentration required to produce a half-maximal effect (EC50) being 26.9 +/- 4.6% (p less than 0.01) and 3 x 10(-7) M, respectively. The U46619-induced increase in CBF was abolished by SQ29548, and TxA2 receptor antagonist, and inhibited by verapamil, a Ca(2+)-entry blocker, and H-7, a protein kinase C inhibitor. These results suggest that TxA2 stimulates ciliary motility through the activation of airway epithelial TxA2 receptors, and that this effect may be exerted from Ca(2+)-influx and protein kinase C.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Prediction of viability of ischemically damaged canine pancreatic grafts by tissue flow rate with machine perfusion.

We studied the viability of canine pancreatic grafts using a short-time perfusion technique with an organ perfusion machine, "ORPH3000C". The following parameters were examined during perfusion of warm ischemically damaged grafts: Amylase, lipase, and insulin levels in the perfusate after 1-hr perfusion showed no significant correlation with warm ischemic time (WIT), and these indices could not be used to assess graft viability. Tissue flow rate (TFR) at the end of perfusion was significantly decreased with prolonged WIT. TFR correlated with the percent decrease in tissue SOD activity, thus TFR was a reliable predictor of reperfusion injury. Histological studies showed no findings attributable to warm ischemic injury before 1-hr perfusion. After 1-hr perfusion, the grafts were allotransplanted and the relation between TFR and endocrine function of the transplanted grafts was examined. TFR correlated with K value calculated from IV-GTT performed on day 5 postoperatively, suggesting that TFR is a predictable index of isolated pancreatic graft viability. Using TFR levels, this method allowed us to select only grafts with good function prior to transplantation. This technique appears to be of use for pancreatic transplantation from cadaver donors after cardiac arrest.

Animals↗
PubMed1992

Genetic and biochemical analysis of ribosomal proteins of minocycline-susceptible and -resistant Mycobacterium smegmatis.

A minocycline (MINO)-resistant mutant was isolated from Mycobacterium smegmatis strain Rabinowitschi. Polypeptide synthesis in the cell-free system prepared from the mutant was resistant to minocycline (MINO) because of alterated 30S ribosomal subunits. Upon two-dimensional gel electrophoresis, two proteins of 30S subunit were found to be altered. MINO resistance phenotype was transferred by mating to the recipient strain P-53. MINO resistance phenotype of a recombinant thus obtained was transferred by a different mating system to the recipient strain Jucho, once again. Ribosomal proteins of each of the donors, recipients and recombinants were analyzed and compared on 2-dimensional (2D) electrophoresis. Approximately 50 ribosomal proteins were observed in 70S ribosomes. Some proteins were differently electrophoresed in different strains. The 30S ribosomal subunits contained at least 19 proteins and 50S ribosomal subunits contained at least 23 proteins. Some proteins were easily washed off during dissociation of subunits in sucrose gradients. At least one protein (designated F) in both subunits was observed at the same position. One protein designated C in 30S subunits could be co-transferred to the recipient cells together with resistance phenotype at the frequency of 100% in the 30 recombinants examined so far. The other protein designated D in 30S subunits could be transferred at the frequency of 86-88%. Three other proteins in 50S subunits could be co-transferred to the recipient strain at a lower frequency. Minocycline resistance, therefore, could be mapped close to genes encoding the structure of ribosomal proteins in M. smegmatis.

Bacterial Proteins↗
PubMed1992

Prostaglandin D2 increases Cl secretion across canine tracheal epithelium through cyclo-oxygenase stimulation and cAMP production.

Prostaglandin (PG) D2 is one cyclo-oxygenase product of arachidonic acid metabolites that may play a role in the pathogenesis of asthma. To determine the effect of PGD2 on ion transport by airway epithelium and its mechanism of action, we measured bioelectric properties of canine cultured tracheal epithelium under short-circuit conditions in vitro. PGD2 (10(-7) M) increased short-circuit current (Isc) from 5.5 +/- 1.2 to 14.1 +/- 2.9 microA cm-2 (means +/- SE, P less than 0.01) when added to the mucosal solution, and to 22.2 +/- 3.8 microA cm-2 (P less than 0.001) when added to the submucosal solution, an effect that was accompanied by the corresponding increases in transepithelial potential difference and conductance. These effects were dose-dependent. The PGD2-induced increase in Isc was not altered by preincubation of cells with autonomic antagonists (phentolamine, propranolol, atropine), the lipoxygenase inhibitor AA-861, the protein kinase C inhibitor H-7, or the Na channel blocker amiloride, but it was inhibited by each of indomethacin, piroxicam, the Cl channel blocker diphenylamine-2-carboxylate, the Cl transport inhibitor furosemide, and Cl-free medium. Intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels were dose-dependently increased by PGD2. These results suggest that PGD2 may selectively stimulate airway epithelial Cl secretion via cyclo-oxygenase- and cAMP-dependent pathway.

Animals↗
PubMed1992

An ordered clone bank for chromosome I of Saccharomyces cerevisiae.

Chromosome I of Saccharomyces cerevisiae DC5 rho 0 was dissected into segments with an average size of 14.0 kb and cloned into lambda phage vectors. The physical maps of the resultant clones, totaling 205.9 kb, were used to construct an ordered clone bank of this chromosome.

Chromosome Mapping↗
PubMed1992

Angiotensin II-1 receptor-mediated Cl secretion by canine tracheal epithelium.

To elucidate the effect of angiotensin II (AII) on ion transport function of airway epithelium, we studied the bioelectrical properties of canine cultured tracheal epithelium under short-circuit conditions in vitro. Addition of AII to submucosal solution in Ussing chambers increased the short-circuit current (ISC) in a dose-dependent fashion, the maximal increase from the baseline value and the concentration required to produce a half-maximal effect being 5.2 +/- 0.5 microA/cm2 (p < 0.001) and 10(-6) M, respectively. In contrast, mucosal AII had little effect. The AII-induced increase in ISC was not altered by the AII-2 receptor antagonist EXP655 but was depressed by the AII-1 receptor antagonist DuP 753. Diphenylamine-2-carboxylate, Cl-free medium, indomethacin, the phospholipase A2 inhibitor mepacrine, and the methyltransferase inhibitor 3-deazaadenosine reduced the change in ISC, whereas amiloride and the lipoxygenase inhibitor AA-861 did not. Addition of AII to the submucosal but not the mucosal side increased the release of prostaglandin E2, an effect that was abolished by DuP 753. These results suggest that AII may interact with the submucosal AII-1 receptor and stimulate Cl secretion across tracheal epithelium through the mobilization of arachidonic acid and the release of prostaglandin E2.

Angiotensin II↗
PubMed1992

Epiderstatin induces the flat reversion of NRK cells transformed by temperature-sensitive Rous sarcoma virus.

Epiderstatin is a unique glutarimide antibiotic which was found by screening for inhibitors of the signal transduction of epidermal growth factor (EGF). The antibiotic (0.01 microM) was found to reverse the morphology of NRK cells that were infected with a temperature-sensitive mutant of Rous sarcoma virus (srcts-NRK) from the transformed phenotype to the normal phenotype at the permissive temperature (32 degrees C). Epiderstatin did not inhibit the protein kinase activity of p60v-src. The cell cycle progression of src(ts)-NRK cells was blocked at G0/G1 phase, which was caused by the inhibition of biosynthesis of p60v-src but not the transcription of v-src mRNA.

Animals↗
PubMed1992

A Clinical Study of Protein Sparing Modified Fast (PSMF) Administered Preoperatively to Morbidly Obese Patients: comparison of PSMF with natural food products to originally prepared PSMF.

Morbidly obese patients are generally in a malnutritional state with an extremely high operative risk. In order to reduce the operative risk, surgeons should make every effort before the operation. A protein sparing modified fast (PSMF) may exhibit its high effectiveness when taken at least for 2 weeks preoperatively. In this study, PSMF prescribed with natural food products was compared with prepared PSMF having an ideal composition from the clinical standpoint. Though it is natural for patients to favor the former, the latter proved to have a superior effect in clinical practice. By performing a PSMF for 2 weeks preoperatively, however, even the PSMF with natural food products seemed to fulfill its purpose sufficiently.

Journal Article↗
PubMed1992

Hepatic Abnormalities in Obesity: comparison between mildly obese cases and morbidly obese cases.

Hepatic morphology and clinical course of mildly obese subjects with abnormal liver tests were determined in comparison with those of surgically treated morbidly obese cases. Twenty mildly obese subjects (mean body mass index, 27.9) with elevated serum transaminase levels were followed up on a low-calorie diet. Nineteen morbidly obese patients (mean body mass index, 39.2) had a surgical biopsy at gastric restrictive surgery. In these two groups, the frequency and the severity of hepatic steatosis and fibrosis were comparable, whereas intralobular cell infiltration was somewhat greater in the mildly obese group. Follow-up studies of the two groups showed remarkable improvement of serum transaminase levels, the extent of which was greater in surgically treated cases. Thus, in mildly obese subjects with abnormal liver tests, (1) hepatic histological abnormalities are not milder than those in morbidly obese cases, and (2) Improvement of serum transaminase levels upon diet therapy is less satisfactory than that in morbidly obese cases treated surgically. It is suggested these two groups may not be in the same spectrum of obesity-related hepatic disorders.

Journal Article↗
PubMed1992

Reveromycins, new inhibitors of eukaryotic cell growth. II. Biological activities.

Reveromycins A, B, C and D showed inhibitory activity against EGF-stimulated mitogen response in Balb/MK cells. Furthermore reveromycins A, C and D exhibited morphological reversion of srcts-NRK cells, antiproliferative activity against human tumor cell lines and antifungal activity. The effects of reveromycins A, C and D on eukaryotic cells were closely similar to each other, but those of reveromycin B were very weak. In vitro studies revealed that reveromycin A is a selective inhibitor of protein synthesis in eukaryotic cells.

Animals↗
PubMed1992

Reveromycins, new inhibitors of eukaryotic cell growth. III. Structures of reveromycins A, B, C and D.

Reveromycins A, B, C and D are new group inhibitors of the mitogenic activity of epidermal growth factor (EGF), produced by Streptomyces sp. Reveromycins are novel polyketide type antibiotics which have two terminal carboxylic groups, a spiroketal, a succinate and a varied side chain in the molecule. Determination of their structures by chemical and spectroscopic methods, in particular NMR studies, is described.

Acetylation↗
PubMed1992

A new inhibitor of protein kinase C, RK-1409B (4'-demethylamino-4'-hydroxy-3'-epistaurosporine).

RK-1409B, a new inhibitor of protein kinase C, was isolated from the culture broth of Streptomyces platensis subsp. malvinus RK-1409. The structure was elucidated on the basis of spectroscopic analyses. RK-1409B inhibited protein kinase C in vitro and the morphological change of a human chronic leukemia cell line, K-562, induced by phorbol 12,13-dibutyrate with IC50 value of 0.4 microM.

Carbazoles↗