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Biomedical subjects

K Okuda

Publications and source records attributed to K Okuda.

At least 487 records · Page 27Linked to original sources
PubMed1992

Granulocyte-macrophage colony-stimulating factor, interleukin-3, and steel factor induce rapid tyrosine phosphorylation of p42 and p44 MAP kinase.

Granulocyte-macrophage colony-stimulating factor (GM-CSF), Interleukin-3 (IL-3), and Steel Factor (SF) induce proliferation of hematopoietic cells through binding to specific, high-affinity, cell surface receptors. However, little is known about postreceptor signal transduction pathways. In previous studies, we noted that each of these three factors could independently support proliferation of the human MO7 cell line, and also that each factor induced a rapid increase in protein-tyrosyl phosphorylation. Although the proteins phosphorylated on tyrosine by GM-CSF and IL-3 are similar or identical in MO7 cells, many of the proteins that are phosphorylated on tyrosine after SF are different. However, two proteins, p42 and p44, were prominently phosphorylated in response to all three of the factors. In MO7 cells, the tyrosyl phosphorylation of p42 and p44 was transient, peaking at 5 to 15 minutes. In contrast to many of the other proteins which are tyrosyl phosphorylated in response to these factors, phosphorylation of p42 and p44 was temperature-dependent, occurring at 37 degrees C, but not at 4 degrees C. We identified the p42 protein as p42 Mitogen-Activated Protein Kinase (p42mapk, ERK-2) and the p44 as a p42mapk-related protein using monospecific antisera to MAP kinase. GM-CSF, IL-3, and SF were each found to induce MAP kinase activity when assayed in vitro using myelin basic protein (MBP) as a substrate. Remarkably, we found that GM-CSF-induced tyrosyl phosphorylation of p42 and p44 even in nonproliferative cells (neutrophils) that respond to this CSF, and that p42 and p44 were two of the most prominently tyrosyl phosphorylated proteins following GM-CSF stimulation of these cells. These results implicate p42mapk and p44 as important signal transducing molecules in myeloid cells, and it is likely that these kinases play a role as part of a sequential "kinase cascade" linking growth factor receptors to mitogenesis and other cellular responses.

Amino Acid Sequence↗
PubMed1992

Tyrosine phosphorylation of rasGAP and associated proteins in chronic myelogenous leukemia cell lines.

The Philadelphia chromosome (Ph1), detected in virtually all cases of chronic myelogenous leukemia, is formed by a reciprocal translocation between chromosomes 9 and 22 that fuses BCR encoded sequences upstream of exon 2 of c-ABL. This oncogene produces a fusion protein (p210BCR/ABL) in which the ABL tyrosine kinase activity is elevated. This elevated kinase activity is essential for transformation, but the mechanisms involved are unknown. We report here that p21ras GTPase activating protein (rasGAP) or rasGAP-associated proteins p190 and p62 are phosphorylated on tyrosine in Ph1 (+) cell lines. Further, rasGAP coimmunoprecipitates with p210BCR/ABL in these cell lines. These results suggest that rasGAP or associated proteins are potential substrates for p210BCR/ABL kinase and thus directly link p210BCR/ABL with a signal transduction pathway known to be activated by hematopoietic growth factors (p21ras).

Fusion Proteins, bcr-abl↗
PubMed1992

Structural gene and complete amino acid sequence of Vibrio alginolyticus collagenase.

The DNA encoding the collagenase of Vibrio alginolyticus was cloned, and its complete nucleotide sequence was determined. When the cloned gene was ligated to pUC18, the Escherichia coli expression vector, bacteria carrying the gene exhibited both collagenase antigen and collagenase activity. The open reading frame from the ATG initiation codon was 2442 bp in length for the collagenase structural gene. The amino acid sequence, deduced from the nucleotide sequence, revealed that the mature collagenase consists of 739 amino acids with an Mr of 81875. The amino acid sequences of 20 polypeptide fragments were completely identical with the deduced amino acid sequences of the collagenase gene. The amino acid composition predicted from the DNA sequence was similar to the chemically determined composition of purified collagenase reported previously. The analyses of both the DNA and amino acid sequences of the collagenase gene were rigorously performed, but we could not detect any significant sequence similarity to other collagenases.

Amino Acid Sequence↗
PubMed1992

Increased expression of the 67kDa-laminin receptor gene in human small cell lung cancer.

Gene expression of the precursor of the 67kDa-laminin receptor was examined by Northern analysis using 11 established human lung cancer cell lines and 25 lung cancer tissues obtained by operation. As a result, one transcript, the size of which was 1.2 kb was shown in all cell lines and tissues examined. An increased level of mRNA was demonstrated in cell lines which proliferated rapidly and in small cell lung cancer cell lines. It was also indicated that gene expression of the laminin receptor was up-regulated especially in small cell lung cancer tissue. In this context, 67kDa-laminin receptor appears to be a marker for biological aggressiveness of human lung cancer.

Adenocarcinoma↗
PubMed1992

Factors involved in the adherence of Candida albicans and Candida tropicalis to protein-adsorbed surfaces. An in vitro study using immobilized protein.

The adherence of Candida albicans and C. tropicalis to protein-adsorbed surfaces was investigated with surface-modified glass slides to which serum or salivary proteins were covalently bound. A specific adherence like a ligand-receptor interaction was observed between C. albicans and mucin- or salivary protein-immobilized glass slides. This interaction was eliminated by deglycosylation of the slides, suggesting that the receptor may be an oligosaccharide(s) contained mucin or saliva. A similar specific interaction was also observed between C. tropicalis and fibrinogen-immobilized glass surfaces. When the numbers of adherent cells to deglycosylated protein-immobilized glass glides were plotted against zeta potentials and contact angles of these protein-immobilized glass slides, a significant correlation was observed between the numbers of adherent cells and zeta potentials in the case of C. albicans (r = -0.87), whereas a significant correlation was observed between cell numbers and contact angles (r = 0.82) in the case of C. tropicalis. These results suggest that the forces governing the adherence of fungi to pellicle in dentures may vary depending upon the surface properties of fungi and substrate.

Adsorption↗
PubMed1992

A new technique of hepatectomy using an occlusion balloon catheter for the hepatic vein.

To minimize intraoperative bleeding and allow more accurate resection, we have devised a new technique for hepatectomy. In addition to occlusion of the afferent vessels, we occlude the hepatic vein at the hepatocaval junction using a balloon catheter inserted transhepatically under intraoperative ultrasonic guidance. We have performed eight hepatectomies using this method. A sequence of 15 minutes of vascular occlusion followed by 5 minutes reperfusion was repeated throughout the operation, and the total ischemic time ranged from 45 to 90 minutes. This method greatly decreased intraoperative bleeding without causing significant elevation of the postoperative transaminase or lactic dehydrogenase levels when compared with occlusion of only the afferent vessels or nonischemic resection using a microwave tissue coagulator in patients undergoing equivalent resections. Also, the postoperative prothrombin time recovered to a significantly higher level, and there were no fatal postoperative complications using this method. Our method is useful for systematic hepatic resection along the hepatic vein or for resection of tumor sited at the confluence of the hepatic vein.

Aged↗
PubMed1992

Histopathology of membranous obstruction of the inferior vena cava in the Budd-Chiari syndrome.

It is generally believed that membranous obstruction of the inferior vena cava in the Budd-Chiari syndrome is caused by congenital malformation. However, it does not explain the late onset of the disease. In the current study, hepatic portion of the inferior vena cava and hepatic veins were studied in 17 autopsy cases of the Budd-Chiari syndrome, 16 of which had no demonstrable cause (idiopathic). A sufficient amount of vena cava tissue was available for evaluation in 15 cases. Nine had membranous obstruction, with thickness varying from 3 to 8 mm. Thrombus formation was recognized in 7 of 9 cases. Occlusion of hepatic vein orifices of varying degree was present in 8 cases. In these occluding lesions, the basic structure of the venous wall was maintained. The intima was transformed into a fibrous laminar structure, and organized thrombi of varying ages were recognized; they were a mixture of fresh thrombi, organized thrombi, fibrous tissues, recanalizations, and calcifications. It is concluded that in these cases of the Budd-Chiari syndrome, occluding and stenosing lesions in the inferior vena cava and hepatic veins were thrombosis and its sequelae. There was no indication of congenital malformation.

Adolescent↗
PubMed1992

Evidence for oxytocin receptors in cultured bovine luteal cells.

Specific receptors for oxytocin (OT) on intact luteal cells are demonstrated. Cultured cells from bovine corpora lutea (CL) at different stages (Days 3-5, 8-12, and 15-18 of the estrous cycle) were examined for OT receptors by a radioreceptor assay using the 125I-labeled OT antagonist [d(CH2)5,Tyr(Me)2,Thr4,Tyr-NH2(9)] -vasotocin. Binding specificity was demonstrated in displacement studies with various related peptides. Scatchard analysis revealed the presence of a binding site with an association constant of Ka = 2.6 x 10(9) M-1 and a capacity of 5.9 fmol/micrograms DNA. Additionally, in 50% of the experiments (n = 6) two different binding sites were observed. The Ka of the high-affinity site was 2.6 x 10(10) M-1; its capacity was 0.73 fmol/micrograms DNA. The low-affinity site had an apparent Ka of 4.9 x 10(8) M-1 and a capacity of 8.8 fmol/micrograms DNA. Observation of one versus two binding sites related neither to the assay conditions nor to the state of the individual CL used for the cell culture and therefore appeared to reflect individual variation within the OT receptor population. Significant binding of OT was observed at all luteal stages. OT binding was maximal at the mid-luteal stage (Days 8-12). We conclude that a direct action of OT on the bovine CL is mediated by the OT receptor, supporting the hypothesis that luteal OT plays an important physiological role in the regulation of progesterone release and/or other luteal functions in a paracrine or autocrine fashion.

Animals↗
PubMed1992

Diagnosis of typhus infection with Rickettsia tsutsugamushi by polymerase chain reaction.

Two sets of oligonucleotide primers were used to amplify the genomic DNA of Rickettsia tsutsugamushi, the causative agent of scrub typhus (tsutsugamushi disease), by the polymerase chain reaction. Each set of primers amplified 538-bp and 109-bp products, representing part of a gene encoding a possible major 58-kDa immunogenic protein, from whole genomic DNA extracted from R. tsutsugamushi strains Karp, Kato, Gilliam, Kuroki and Kawasaki. No amplification was observed from R. sibirica, R. rickettsii, mouse and human genomic DNA. DNA amplification was observed from crude lysates of peripheral whole blood, tissue homogenates and paraffin-embedded skin biopsy sections obtained from patients with scrub typhus disease. Southern blot analysis demonstrated the specificity of the amplified DNA fragments following hybridisation with a DNA probe generated from R. tsutsugamushi strain Karp. By means of this procedure, a rapid and sensitive diagnosis of scrub typhus disease can be made during the acute stage of this infection.

Acute Disease↗
PubMed1992

An epidemiological study of methicillin-resistant Staphylococcus aureus (MRSA) isolated from medical staff, inpatients, and hospital environment in one ward at our hospital.

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important causative microorganisms for nosocomial infections. Recently, the incidence of isolation of MRSA has been increasing every year in Japan and is, notably, much more frequently found in inpatients than in outpatients. Therefore, we have done epidemiological studies of MRSA isolated from medical staff, inpatients, and the hospital environment in one ward of our hospital. Thereafter, we examined the antibiotic susceptibility (ABPC, DMPPC, CET, CMZ, IPM, GM, MINO, OFLX, EM, CLDM, VCM), phage typing, and coagulase typing of these MRSA. MRSA were isolated more frequently from anterior nares of inpatients than from doctors and nurses. MRSA were isolated more frequently from the environment near carriers of MRSA. Coagulase type II and phage type N.T. (not typable) were the dominant types of MRSA in our hospital (69% and 61%). MRSA strains were resistant to most antibiotics with a few exceptions (VCM, IPM, CMZ, CET). The high isolation frequency of MRSA in our hospital seems to suggest that inpatients who are carrying MRSA spread MRSA throughout the hospital environment and that the anterior nares of inpatients are the major MRSA harbor.

Air Microbiology↗
PubMed1992

A sensitive enzymatic method (SK-013) for detection and quantification of specific periodontopathogens.

Porphyromonas gingivalis, Bacteroides forsythus, and Treponema denticola have been found to predominate in periodontal pockets of patients with adult periodontitis. These microorganisms hydrolyze the synthetic peptide N-benzoyl-DL-arginine-2-naphthylamide (BANA). In this study, we developed an enzymatic method, designated SK-013, to detect the existence of these microorganisms in subgingival plaque bacteria. This enzymatic method was based on the observation of the hydrolysis of N-carbobenzoxy-glycyl-glycyl-arginyl-3,5-dibromo-4-hydroxyaniline (N-CBz-Gly-Gly-Arg-DBHA) and made more sensitive by adding an enhancing system. The SK-013 was specifically positive for P. gingivalis, B. forsythus, T. denticola, and some strains of Capnocytophaga species, but was not specific for any of the other bacterial strains tested. This SK-013 system may be valuable for detection and quantification of periodontal disease-associated bacteria in subgingival plaque and thus for diagnosis of periodontal infections.

Bacteroides↗
PubMed1992

A sensitive enzymatic method (SK-013) for detection of Treponema denticola, Porphyromonas gingivals and Bacteroides forsythus in subgingival plaque samples.

An enzymatic method, SK-013, was developed for rapid detection of the peptidase activity in subgingival plaque samples. This method was found to have specificity for Porphyromonas gingivalis, Treponema denticola, Bacteroides forsythus, and some Capnocytophaga strains. The purpose of this study was to determine whether SK-013 could indicate the presence of periodontopathic bacteria, including T. denticola, P. gingivalis and B. forsythus, which produce trypsin-like enzymes. Subgingival plaque samples were taken from 10 clinically healthy sites and 30 periodontally diseased sites with 3 paper points. SK-013 activity of plaque samples was assayed, and the numbers of T. denticola, P. gingivalis and B. forsythus in the sample were counted by immunofluorescence technique. In diseased sites, the SK-013 activity was significantly correlated with clinical parameters such as Gingival Index, Plaque Index, probing depth and bleeding on probing. A significant correlation was found between the presence of these organisms and SK-013 activity. Correlation coefficients between the presence of T. denticola and SK-013 activity were higher than those with other organisms. These findings indicate that the SK-013 is useful as an indicator of cell population of T. denticola, P. gingivalis and B. forsythus in subgingival plaque.

Bacteroides↗
PubMed1992

Cloning and expression of the aspartate carbamoyltransferase gene from Treponema denticola.

Treponema denticola seems to play a central role in the etiology of human periodontal disease. We have cloned an antigenic protein-coding sequence from T. denticola ATCC 33520. The protein-coding region was found to be a 3-kbp HindIII-HindIII fragment. The open reading frame consists of 1,426 bp and codes for a protein with an M(r) of 54,919. The deduced amino acid sequence showed 33.8% homology with that of the aspartate carbamoyltransferase of Escherichia coli. The gene products showed aspartate carbamoyltransferase activity.

Amino Acid Sequence↗
PubMed1992

Regional myocardial perfusion and glucose metabolism in experimental left bundle branch block.

BACKGROUND: Several authors have reported cases in which 201Tl scintigraphy demonstrated perfusion abnormality in the septum of patients with left bundle branch block (LBBB) and normal coronary arteriogram. The mechanism of this abnormality, however, remains to be clarified. METHODS AND RESULTS: To determine whether LBBB itself induces abnormal myocardial perfusion and ischemia and to elucidate its mechanism, we used an in vivo animal model. LBBB was induced by right ventricular pacing in 17 open-chest dogs. We examined myocardial perfusion and glucose uptake using 201Tl and 18F-labeled 2-fluoro-2-deoxy-D-glucose. 201Tl activity in the septum was reduced to 74.7 +/- 14.5% of its maximal activity, and mean activity was 86.5 +/- 5.3% in the free wall (p less than 0.05). 18F activity in the septum was also reduced compared with that in the free wall (67.4 +/- 12.1% versus 88.0 +/- 5.2%, p less than 0.05). Regional myocardial blood flow was significantly reduced in the septum compared with the free wall, averaging 0.53 +/- 0.18 ml/min/g versus 0.84 +/- 0.14 ml/min/g, respectively (p less than 0.01). Systolic thickening in the septum was reduced from 1.36 +/- 0.20 to 0.98 +/- 0.04 (p less than 0.01) after the induction of LBBB, and the intramyocardial pressure in the septum in diastolic phase, in which the major flow of left anterior descending coronary artery (LAD) exists, increased from 26.6 +/- 10.5 to 57.8 +/- 22.2 mm Hg (p less than 0.02). Mean aortic pressure, LAD flow, and lactate extraction rate showed no significant change. CONCLUSIONS: LBBB itself may reduce myocardial perfusion and glucose uptake in the septum because of impaired systolic thickening and augmented intramyocardial pressure in the septum; however, this is not necessarily related to septal ischemia.

Animals↗
PubMed1992

Effect of diltiazem on stunned myocardium evaluated with 99mTc-pyrophosphate imaging in canine heart.

The effect of diltiazem on stunned myocardium was evaluated by measuring the myocardial uptake of 99mTc-PYP (pyrophosphate) in open chest experiments with dogs. Myocardial stunning was induced by a 30 min ischemic occlusion of the anterior descending coronary artery. Regional wall motion was monitored by echocardiography of the epicardium for 2 h during reperfusion. After a 30 min occlusion of the coronary artery, it was reperfused and 99mTc-PYP was injected, followed by 201Tl 2 h later. The ischemic area was defined by Evans blue dye, and the infarct area by TTC staining. No dogs showed infarcts or 201Tl defects in this study group. Five dogs of the control-1 group (C1, ischemic area = 19.1 +/- 3.2%) showed decreased regional wall motion during occlusion (15.5 +/- 3.5% of control), and a slow recovery from depressed motion after 2 h of reperfusion (20.3 +/- 9.3%) with uptake ratio (compared to the non-ischemic area uptake) of 99mTc-PYP (4.96 +/- 2.28). In contrast, both groups with diltiazem infusion (20 micrograms/kg/min), started either 30 min before ischemia (D1 = 5 dogs) or just after reperfusion (D2 = 5 dogs), showed significantly better recovery after 2 h of reperfusion (D1:115.4 +/- 36.0%, D2:109.2 +/- 44.2%) than C1 (p less than 0.05), D1 and D2 groups also showed suppressed 99mTc-PYP uptake ratio (D1:1.06 +/- 0.33, D2:2.34 +/- 2.05, p less than 0.05 vs C1) in spite of comparable ischemic area. Four dogs with small ischemic area (C2:5.3 +/- 5.0%) did not show increased 99mTc-PYP uptake (1.15 +/- 0.35), and regional wall motion after 2 h of reperfusion was 96.1 +/- 24.1% of the control value (p less than 0.05 vs C1). Thus, diltiazem was effective in enhancing the suppression of 99mTc-PYP uptake in the stunned myocardium, and similar results were obtained for small ischemic areas. The protective effect of diltiazem appears to be strongly related to the mechanism of 99mTc-PYP uptake.

Animals↗
PubMed1992

Effects of basic fibroblast growth factor, transforming growth factor-beta and nerve growth factor on the secretory function of the bovine corpus luteum in vitro.

The effects were investigated of basic fibroblast growth factor (bFGF), transforming growth factor-beta (TGF-beta) and nerve growth factor (NGF) on the release of progesterone and oxytocin from the bovine corpus luteum (CL) at different stages of the oestrous cycle. A microdialysis system (MDS) of CL and a cell culture system with a reduced number of endothelial cells were used. In the MDS of CL from the mid-luteal stage (days 8-12 of the oestrous cycle), infusion with bFGF (0.1, 1, 10 and 100 ng/ml), TGF-beta (0.1, 1 and 10 ng/ml) and NGF (0.1, 1, 10 and 100 ng/ml) for 30 min induced significant acute effects on the release of progesterone. Both bFGF and NGF stimulated the release of progesterone during peptide infusion, TGF-beta and also bFGF in the period thereafter. This stimulation was dose-dependent during and after the infusion only for bFGF. This response pattern was observed at all luteal stages for the three growth factors, but bFGF was more stimulatory at the early (days 5-7) and mid-luteal stages during and after peptide infusion. The release of oxytocin was stimulated by bFGF in a dose-dependent manner. At the highest dose, bFGF, TGF-beta and NGF stimulated the release of oxytocin throughout all three luteal stages. When luteal cells were cultured with growth factors, only TGF-beta showed a dose-dependent inhibition of both basal and LH-stimulated progesterone as well as oxytocin release (measured between 48 and 52 h of culture). NGF had an inhibitory effect only on the basal release of oxytocin. bFGF had no effect on the release of either hormone under continuous stimulation in cell culture. The results indicate that bFGF, TGF-beta and NGF act directly and acutely on the secretory function of bovine CL in the MDS but also have long-term effects as shown in cell culture. bFGF appears to be an important autocrine/paracrine regulator of CL function, since local expression of its mRNA, peptide synthesis and its mitogenic and non-mitogenic actions have now been confirmed. Endothelial cells from the CL have been identified as target cells for bFGF. Differences observed between the two systems might thus be attributed to the presence or absence of cell-to-cell contact and a reduced number of endothelial cells, as well as to the duration of peptide stimulation and medium changes every 24 h compared with the flow-through conditions in the MDS.

Animals↗
PubMed1992

Minocycline slow-release formulation effect on subgingival bacteria.

The purpose of this study was to determine the microbiological efficacy of an adjunctive minocycline periodontal formulation delivered subgingivally. Subjects were systemically healthy but exhibited severe periodontitis; i.e., probing depths greater than 6 mm. The two study groups included individuals who received minocycline or a placebo periodontal formulation after root planing. Subgingival plaque samples were obtained at baseline; prior to treatment; and at 1, 3, and 6 months. Plaque was evaluated by darkfield microscopy and further analyzed for total dark-pigmented Bacteroides species, P. intermedia, P. gingivalis and Streptococcus, Actinomyces, Eikenella, Actinobacillus, Capnocytophaga, and Fusobacterium species using cultivable flora techniques. In addition, plaque was evaluated for yeast on a selective agar medium. When compared to the placebo, the minocycline group had significantly lower proportions of spirochetes at 1 and 3 months and lower proportions of motile rods at 3 months. Furthermore, when compared to the placebo group, the minocycline patients had lower mean proportions of dark-pigmented Bacteroides spp. and P. intermedia at 1 and 3 months as well as lower proportions of E. corrodens at 1 month. The minocycline group had significant decreases in proportions of spirochetes at 1 and 3 months, motile rods at 1 and 3 months, and increases in cocci at 1, 3, and 6 months when compared to baseline. In the placebo group, root planing was also effective at decreasing spirochetes at 1, 3, and 6 months, but with significant differences seen only at 3 and 6 months. However, the degree of reduction in spirochete proportions was greater in the minocycline group when compared with the placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinomyces↗