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Biomedical subjects

T Kondo

Publications and source records attributed to T Kondo.

At least 325 records · Page 18Linked to original sources
PubMed1999

A conspicuous adaptability to antibiotics in the Escherichia coli mutator strain, dnaQ49.

By repeating the cycle of mutagenesis and selection, the Escherichia coli dnaQ49 mutator acquired high level resistance to ampicillin (30,000 micrograms ml-1), streptomycin (26,000 micrograms ml-1) and ofloxacin (3000 micrograms ml-1). Under the strong pressure of ofloxacin, dnaQ49 also followed the history of mutations in the gyrase and topoisomerase i.v. genes previously observed in clinical isolates of quinolone-resistant E. coli. The results of these in vitro experiments suggest that naturally existing mutators may participate in the rapid acquisition of resistance to various antibiotics in patients. A possible mechanism for the occurrence of this adaptability is discussed with special reference to the property of mutagenesis accompanying DNA replication.

Amino Acid Sequence↗
PubMed1999

Physical interaction and functional antagonism between the RNA polymerase II elongation factor ELL and p53.

ELL was originally identified as a gene that undergoes translocation with the trithorax-like MLL gene in acute myeloid leukemia. Recent studies have shown that the gene product, ELL, functions as an RNA polymerase II elongation factor that increases the rate of transcription by RNA polymerase II by suppressing transient pausing. Using yeast two-hybrid screening with ELL as bait, we isolated the p53 tumor suppressor protein as a specific interactor of ELL. The interaction involves respectively the transcription elongation activation domain of ELL and the C-terminal tail of p53. Through this interaction, ELL inhibits both sequence-specific transactivation and sequence-independent transrepression by p53. Thus, ELL acts as a negative regulator of p53 in transcription. Conversely, p53 inhibits the transcription elongation activity of ELL, suggesting that p53 is capable of regulating general transcription by RNA polymerase II through controlling the ELL activity. Elevated levels of ELL in cells resulted in the inhibition of p53-dependent induction of endogenous p21 and substantially protected cells from p53-mediated apoptosis that is induced by genotoxic stress. Our observations indicate the existence of a mutually inhibitory interaction between p53 and a general transcription elongation factor ELL and raise the possibility that an aberrant interaction between p53 and ELL may play a role in the genesis of leukemias carrying MLL-ELL gene translocations.

Cell Compartmentation↗
PubMed1999

Cellular balance of glutathione levels through the expression of gamma-glutamylcysteine synthetase and glutathione thiol transferase genes in human hepatic cells resistant to a glutathione poison.

Buthionine sulfoximine (BSO) is a synthetic amino acid that irreversibly inhibits glutathione biosynthesis and deranges reduced glutathione (GSH) metabolism in liver cells. We isolated two BSO-resistant lines, HLE/BSO2-1 and HLE/BSO2-2, from human hepatic HLE/WT cells. Cellular levels of the Pi class glutathione thiol transferase (GSTP1) were 3-fold lower in BSO-resistant lines than in HLE/WT cells. By contrast, gamma-glutamylcysteine synthetase (GCS) heavy subunit (GCSh) mRNA levels were markedly decreased in HLE/BSO2-1 and HLE/BSO2-2 as compared with HLE/WT. The expression of a dominant-negative mutant of c-Jun inhibited the GCSh promoter activity in HLE/WT, but not in HLE/BSO2-1. Cellular levels of AP-1, however, were not decreased in either BSO-resistant cell line. Transfection of GCSh promoter of various lengths driven reporter constructs showed no sequence-specific increase in the promoter activities in HLE/BSO2-1. However, transfection of GSTP1 cDNA into HLE/BSO2-1 and HLE/BSO2-2 restored the levels of GCSh mRNA and the GCSh promoter activity to those of HLE/WT. Sequences between -315 and -241 bp of the 5' region contained an AP-1 site responsible for the enhanced GCSh promoter activity in GSTP1 transfectants of HLE/BSO2-1. In vivo footprint analysis showed a specific protection of the AP-1 site on GCSh promoter in GSTP1 transfected HLE/BSO2-1. GSH homeostasis thus appears to be maintained by an interaction between GSTP1 and GCS in human hepatic cells resistant to the GSH poison.

Buthionine Sulfoximine↗
PubMed1999

Breaking colinearity in the mouse HoxD complex.

Vertebrate Hox genes are activated in a spatiotemporal sequence that reflects their clustered organization. While this colinear relationship is a property of most metazoans with an anterior to posterior polarity, the underlying molecular mechanisms are unknown. Previous work suggested that Hox genes were made progressively available for transcription in the course of gastrulation, implying the existence of an element capable of initiating a repressive conformation, subsequently relieved from the clusters sequentially. We searched for this element by combining a genomic walk with successive transgene insertions upstream of the HoxD complex followed by a series of deletions. The largest deficiency induced posterior homeotic transformations coincidentally with an earlier activation of Hoxd genes. These data suggest that a regulatory element located upstream of the complex is necessary for setting up the early pattern of Hox gene colinear activation.

Animals↗
PubMed1999

Morphological findings of 'cardiac concussion' due to experimental blunt impact to the precordial region.

The dog's precordial region at the sternum was impacted with a mechanical elastic-cord propelled impactor at the velocity of 8.0 m/s. The left and right intraventricular pressures and electrocardiogram (ECG) were monitored continuously for 60 min after the impact. The micro- and ultra-structure of myocardium were examined. Localization of myocardial myoglobin (Mb), creatine kinase BB (CK-BB) and creatine kinase MM (CK-MM) as well as plasma membrane permeability were studied by immunohistochemical and lanthanum probe techniques. Upon the impact, abrupt over-pressures within both ventricles were recorded with transient depression of the left ventricular systolic pressure. In all the dogs, some rhythm- and conduction-disorders were noted, which lasted transiently and resumed to normal sinus rhythm. At autopsy, no gross injuries of the heart were detected, and microscopic examination showed no visible myocardial lesions. However, immunohistochemically, focal patchy loss of myocardial Mb, CK-BB and CK-MM was identified with scattered deposition of these substances between myocardial fibers elsewhere. Such changes as relaxed myofibrils with widened I band, contracted myofibrils and broken cristae of the mitochondria were observed in myocardial ultrastructure. Lanthanum particles deposited inside the mitochondria. These results indicate that increase in cardiac cell membrane permeability and ultrastructural damage in myocardium may be involved even in cardiac concussion.

Animals↗
PubMed1999

Physical interactions among circadian clock proteins KaiA, KaiB and KaiC in cyanobacteria.

The kai gene cluster, which is composed of three genes, kaiA, kaiB and kaiC, is essential for the generation of circadian rhythms in the unicellular cyanobacterium Synechococcus sp. strain PCC 7942. Here we demonstrate the direct association of KaiA, KaiB and KaiC in yeast cells using the two-hybrid system, in vitro and in cyanobacterial cells. KaiC enhanced KaiA-KaiB interaction in vitro and in yeast cells, suggesting that the three Kai proteins were able to form a heteromultimeric complex. We also found that a long period mutation kaiA1 dramatically enhanced KaiA-KaiB interaction in vitro. Thus, direct protein-protein association among the Kai proteins may be a critical process in the generation of circadian rhythms in cyanobacteria.

Amino Acid Sequence↗
PubMed1999

Streptococcus equi but not Streptococcus zooepidemicus produces potent mitogenic responses from equine peripheral blood mononuclear cells.

Streptococcus equi causes equine strangles. The acute disease has many of the hallmarks of an acute response including high fever, elevated plasma fibrinogen and neutrophilia, affects known to be mediated by proinflammatory cytokines. The objective of this study was to screen-culture supernatants from equine clinical isolates of S. equi and S. zooepidemicus for stimulation of mitogenic responses by horse peripheral blood mononuclear cells. Mitogenicity comparable to that of concanavalin A was detected in culture supernatants of S. equi strains but not in those of S. zooepidemicus. Mitogenicity was neutralised by Proteinase K and a post-strangles convalescent serum, and evidence for the presence of both thermo-resistant and thermo-labile mitogenic factors was obtained. Release of proteinaceous immunogenic mitogens in combination with the antiphagocytic protein SeM unique to S. equi may therefore contribute to some of the severe clinical manifestations of acute strangles in the horse.

Animals↗
PubMed1999

Five-year survivors with resected pN2 nonsmall cell lung carcinoma.

BACKGROUND: Some patients with resected pN2 lung carcinoma were long term survivors. To determine appropriate therapeutic modalities for the selected patients, the clinicopathologic characteristics of these patients were examined using the actual number of survivors rather than the cumulative survival rate because the cumulative survival rate occasionally is confounded due to patients with short follow-up periods. METHODS: Between 1981-1990, 178 patients with pN2 nonsmall cell lung carcinoma underwent complete resection with systemic lymph node dissection. The ratios of 5-year survivors to all patients in groups with several clinicopathologic factors were compared. RESULTS: Gender, the side that was operated on, location of the tumor, histologic type, or surgical procedure were not related to the ratio of 5-year survivors. However, T classification, skip metastasis, and the number of levels involved were associated with the ratio significantly. The authors also found that the location of the involved lymph node(s) affected the ratio. CONCLUSIONS: Even in the presence of pN2 disease, lung carcinoma patients with T1 tumors, skip metastasis, or single level mediastinal lymph node involvement, especially Level 4, Level 5, or Level 6 lymph nodes, had a relatively favorable prognosis and may be candidates for primary resection.

Carcinoma, Non-Small-Cell Lung↗
PubMed1999

Transalveolar fluid absorption ability in rat lungs preserved with Euro-Collins solution and EP4 solution.

BACKGROUND: Pulmonary reimplantation response, presenting lung edema, is a major obstacle of lung transplantation. Transalveolar fluid absorption mechanism, regulated by active transalveolar Na+ transport via Na+ channel and Na+-K+-ATPase, is considered to be essential for resolution of lung edema. We investigated the effect of lung preservation on this fluid transport mechanism. METHODS: The rat lungs were flushed and preserved with either EP4 solution (EP4) or Euro-Collins solution (EC). First, we determined the basal transalveolar fluid movement by calculating alveolar fluid clearance (AFC) after pulmonary flushing, 24- and 72-hr preservation. Then, we assessed the effects of Na+ channel blocker, amiloride, and Na+-K+-ATPase inhibitor, ouabain, on AFC after 24-hr preservation. We further measured lung ATP content and Na+-K+-ATPase activity after 24-hr preservation to evaluate cellular metabolism and enzymatic activity during preservation. RESULTS: We found that the lungs preserved with EC showed significantly lower AFC and less inhibitory effects of both blockers than with EP4 after 24-hr preservation. Na+-K+-ATPase activity was significantly lower with EC than with EP4, even though lung ATP content was not affected by preservation solution. CONCLUSIONS: EP4 preservation provides a better environment for maintaining transalveolar fluid absorption mechanism than EC preservation. Therefore, lung preservation with EP4 may ensure more reliable ability in resolving pulmonary edema.

Adenosine Triphosphate↗
PubMed1999

Association between duration of obesity and risk of non-insulin-dependent diabetes mellitus. The Sotetsu Study.

The authors investigated the association between duration of obesity (ordinary obesity as body mass index (BMI) (kg/m2) > or = 25.0 and extreme obesity as BMI > or = 27.8) and the risk of diabetes mellitus. Male employees of a railway company, aged 30 years or older, observed for 10 years or more, free from serious disease conditions, with initial BMI <25.0, aged 30 years or more at the time diabetes was diagnosed, and with complete data, were examined by univariate and multivariate analyses (n = 1,598). Age-adjusted odds ratios for diabetes were significantly increased among males who were obese for 10-19.9 years and >20 years (odds ratios = 2.10 and 2.84 for ordinary obesity and 6.14 and 4.15 for extreme obesity, respectively). Additional adjustment for current obesity, physical activity, smoking, drinking, family history, and observation period did not change the findings remarkably. In conclusion, > or = 10 years duration of ordinary obesity or > or = 1 year of extreme obesity was an important predictor for diabetes independent of age, current obesity, physical activity, smoking, drinking, family history, and observation period.

Adult↗
PubMed1999

Identification of autoimmune T cells among in vivo expanded CD25+ T cells in multiple sclerosis.

Although clonal expansion of autoimmune T cells has been reported in multiple sclerosis (MS), very limited information is available on specificities, clonal size, or activation state of the expanded clones. Here we address the issue of clonal expansion by using a novel technique demonstrating clonotypes defined by single-strand conformation polymorphism of TCR beta-chain cDNAs. Examination of activated T cells (CD3+CD25+) isolated from the peripheral blood of MS revealed limited numbers (20 approximately 82) of expanded clones defined by single-strand conformation polymorphism clonotype. To estimate the Ag specificities of dominant clonotypes in the activated T cells, these samples were examined in parallel with Th1 T cell clones specific for myelin basic protein or proteolipid protein (PLP) derived from the same patients. Analysis of two patients demonstrated that the dominant clonotypes would contain those specific for myelin basic protein or PLP. Although the majority of the clonotypes could be detected only transiently, a PLP95-116-specific clonotype was found to persist for over 1 yr. Thus, single-strand conformation polymorphism clonotype analysis allows us to monitor the kinetics of given T cell clones in vivo and could provide useful information for designing clonotype (Id)-specific manipulation of human diseases such as MS.

Adult↗
PubMed1999

Selective transendothelial migration of hematopoietic progenitor cells: a role in homing of progenitor cells.

To elucidate the mechanisms by which hematopoietic progenitor cells transmigrate via the bone marrow (BM) endothelial cells, we first established endothelial cell lines from BM and lung, and BM fibroblast cell lines; then we established an in vitro model of transendothelial migration of hematopoietic progenitor cells in the presence of chemoattractants secreted by BM fibroblast cells. The BM endothelial cells expressed vascular cell adhesion molecule-1 (VCAM-1), but the lung endothelial cells did not. The BM fibroblast cells secreted chemoattractants including stroma cell-derived factor (SDF)-1, which could attract hematopoietic progenitor cells to BM and activate the adhesion molecules expressed on hematopoietic progenitor cells after rolling along the endothelial cells. Anti-SDF-1 antibody inhibited the transendothelial migration of a hematopoietic progenitor cell line, FDCP-2. FDCP-2 that expressed very late activation antigen-4 (VLA-4) and normal progenitor cells transmigrated through BM endothelial cells but not lung endothelial cells, even if in the presence of chemoattractants produced by BM fibroblasts. Both anti-VLA-4 and anti-VCAM-1 antibodies inhibited the transendothelial migration of FDCP-2 cells and normal hematopoietic progenitor cells. These findings suggest that the transendothelial migration of hematopoietic progenitor cells is characteristic of BM endothelial cells, and that VLA-4/VCAM-1 and SDF-1 play important roles in the transendothelial migration and, consequently, homing of hematopoietic progenitor cells to BM.

Animals↗
PubMed1999

Regulatory role of endogenous interleukin-10 in cutaneous inflammatory response of murine wound healing.

This study investigated the role of endogenous interleukin (IL)-10 in cutaneous wound healing. Both IL-10 mRNA and protein were detectable in murine incised wounds for 10 days after injury. The IL-10 protein level peaked 3 h after incision, returned to the normal level by 24 h, but increased again to another peak at 72 h. In situ hybridization studies and immunostaining revealed that epidermal cells and infiltrating mononuclear cells were the major source of IL-10. Neutralizing antibody studies demonstrated that IL-10 inhibited the infiltration of neutrophils and macrophages toward the site of injury. IL-10 also inhibited overexpression of C-C chemokines (monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha) and proinflammatory cytokines (IL-1beta, IL-6, tumor necrosis factor-alpha) in vivo. These results suggest that IL-10 may play an important regulatory role in the phase-specific infiltration of neutrophils and macrophages as well as the cytokine production in the inflammatory response of cutaneous wound healing.

Animals↗
PubMed1999

Prevention of hepatic ischemia-reperfusion injury by SOD-DIVEMA conjugate.

A protective effect of the SOD (superoxide dismutase)-DIVEMA (divinyl ether and maleic anhydride) conjugate on I-R (ischemia-reperfusion) liver injury was demonstrated. Twenty minutes of normothermic hepatic ischemia was induced by clamping the portal triad of Sprague-Dawley rats. Five minutes before the end of ischemia, SOD, SOD-DIVEMA, or NaCl (0.9%) was given intravenously. Using intravital fluorescence microscopy, hepatic microvascular perfusion was analyzed before ischemia and repeatedly during the 120-min reperfusion period. SOD-DIVEMA significantly restored the sinusoidal perfusion rate (control, 98.0 +/- 0.5; NaCl, 65.5 +/- 7. 7; SOD, 81.5 +/- 8.2; SOD-DIVEMA, 95.8 +/- 0.7%) and reduced the number of leukocytes stagnant in acini (control, 4.4 +/- 0.9; NaCl, 36.6 +/- 6.3; SOD, 27.7 +/- 6.8; SOD-DIVEMA, 12.3 +/- 3.3 cells/lobule) and adherent in postsinusoidal venules (control, 55.0 +/- 24; NaCl, 417 +/- 63; SOD, 253 +/- 58; SOD-DIVEMA, 40.0 +/- 14 cells/mm2). In addition, SOD-DIVEMA maintained postischemic hepatocellular integrity. The SOD-DIVEMA-treated group revealed higher serum SOD enzyme activity compared to the SOD group after 120 min of reperfusion (SOD-DIVEMA, 33.0 +/- 5.9; SOD, 8.6 +/- 3.1 U/ml). The beneficial effect of SOD-DIVEMA was most prominent after 120 min of reperfusion, indicating a longer intravascular half-life of SOD-DIVEMA.

Animals↗
PubMed1999

Vacuolating cytotoxin purified from Helicobacter pylori causes mitochondrial damage in human gastric cells.

We investigated the effects of vacuolating cytotoxin (VacA) prepared from Helicobacter pylori on the metabolism of gastric epithelial cells, AZ-521. VacA caused the ATP levels to decrease in a time-dependent manner; by approximately 20% in 6 h, 35% in 12 h and 50% in 24 h, at a concentration of 120 nM. This decrease was also dependent on the concentration of VacA. To evaluate the impairment of mitochondria by VacA, mitochondrial membrane potential was estimated by flow cytometric analysis using 3, 3'-dihexyloxacarbocyanine iodide as a substrate. VacA decreased membrane potential with the relative fluorescence intensity of AZ-521 cells in 6 h from 52+/-3 to 24+/-1. Treatment of the cells with bafilomycin A1, a specific inhibitor of vacuolar ATPase proton pump, showed no apparent effect on these changes in the levels of ATP and the mitochondrial membrane potential. Secondly, we estimated the effect of VacA on oxygen consumption. VacA inhibited oxygen consumption in AZ-521 cells: the levels of PO 2 in the medium of control cells decreased by 73% in 3 h and 37% in 6 h, whereas those in VacA-treated cells were 84% in 3 h and 59% in 6 h. Flow cytometric analysis showed the number of cells in the G0/G1 phase was increased by VacA. Taken together, VacA induced an inactivation of energy metabolism followed by mitochondrial damage, leading to impairment of the cell cycle in gastric epithelial cells.

Adenocarcinoma↗
PubMed1999

Economic evaluation of alternative indicators for screening for diabetes mellitus.

BACKGROUND: the optimal indicator for screening for diabetes mellitus without relying on fasting conditions was clarified. METHODS: the subjects were 891 men ages 26 through 80 years (48.5 +/- 8.5). The objectives of this study were (1) to elucidate the efficacy of 1,5-anhydroglucitol (1,5-AG), glycosylated hemoglobin, and fructosamine (FRA) as screening tests for non-insulin-dependent diabetes mellitus (NIDDM) or for impaired glucose tolerance (IGT) and (2) to perform an economic evaluation for each indicator. The efficacy of each indicator was evaluated by drawing the receiver operating characteristic curves and calculating the areas under these curves (AUCs). An original model was developed for the pur pose of cost-effectiveness analysis. RESULTS: each indicator was evaluated as a screening test for NIDDM alone and for both IGT and NIDDM. The AUCs of 1,5-AG and fasting plasma glucose were the largest in the case of the detection of NIDDM alone and the detection of both IGT and NIDDM, respectively. FRA was, however, the most cost-effective in Japan. CONCLUSION: using equations, we indicated the equi librium points at which the cost-effectiveness ratios of each indicator intersected in order to generalize the results. By calculating the appropriate-actual ratios of costs for each indicator, we could ascertain the optimal indicator for each country.

Adult↗
PubMed1999

Left sleeve pneumonectomy performed through a clamshell incision with extracorporeal membrane oxygenation for bronchogenic carcinoma: report of two cases.

We report herein the cases of two patients with bronchial gland carcinomas in the left main bronchus who were successfully treated by left sleeve pneumonectomy performed through a clamshell incision. Adequate oxygenation during pathological examination of tumor invasion at the bronchial stumps and the tracheobronchial anastomoses was achieved by extracorporeal membrane oxygenation (ECMO) in both patients. Tracheobronchial anastomosis was relatively easy to perform in the excellent operative field achieved by this method. The postoperative courses of both patients were uneventful, although they developed temporary pulmonary edema that was effectively controlled by mechanical ventilation and appropriate diuresis. The procedure presented in this paper is considered to be a safe and effective method of performing left sleeve pneumonectomy.

Adult↗