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Biomedical subjects

K Yagi

Publications and source records attributed to K Yagi.

At least 397 records · Page 22Linked to original sources
PubMed1992

[The immunohistochemical study on the recurrent mechanism of acetic acid induced gastric ulcer in rats--extracellular matrix and cellular kinetics].

The localization of fibronectin (FN) and laminin (LM) and cellular kinetics of epithelium in acetic acid induced gastric ulcers were examined by immunohistochemistry, comparing fundic glands ulcer with fundic-pyloric border ulcer. Ulcers on fundic glands had become scars in 30 days and didn't relapse after that. More than half of ulcer on fundic-pyloric border changed into scar in 30 days, however, they started to recur at about 45 days. The localization of LM was observed on basement membrane (BM) beneath epithelia, blood vessel walls and musculature. The percentage change in intra-blood-vessel area compared to total area was analyzed by immunohistochemical distribution of LM. As for ulcer on fundic glands, the percentage of intra-blood-vessel returned to normal numbers after healing to scars (30 days). On the other hand, the percentage of intra-blood-vessel of ulcer on fundic-pyloric border after changing into scar (30 days) and recurring (45 days) significantly increased compared with initial healing (10 days, 20 days). The stratum of spindly cells with FN-positive surface appeared under regenerative epithelia of ulcers on fundic-pyloric border from 10 days to 20 days. This part was proven to be spare in blood vessels by distribution of LM. Though this stratum was not observed at every stages after recurrence, the collagen fibers of ulcer on fundic-pyloric border had got mature thickly. These results may lead the following theory; the phenomenon that the distribution of blood supply in stomach seems to be more dominant in submucosal fibrous layer than in mucosa may cause the recurrence of fundic-pyloric border ulcers. The cell number of S-phase was significantly more numerously observed in relapsed ulcer on fundic-pyloric border than in pre-relapsed one (10 day). The cell number of S-phase on fundic gland ulcer tended to decrease after healing to scar stage. The immediate restoration of connective tissue under the mucosa is considered to promote epithelial cellular kinetics in recovering and maturing.

Acetates↗
PubMed1992

[Basic research for interferon gene therapy against malignant glioma].

In order to establish new interferon therapy against malignant glioma by selective transfection of its gene, we developed a novel transfection system using liposomes bearing positive charges on their surface and entrapping plasmids containing the HuIFN- beta gene (pSV2IFN-beta). The liposomes were composed of N-(alpha -trimethylammonioacetyl) -didodecyl-D-glutamate chloride (TMAG), dilauroylphosphatidylcholine (DLPC), and dioleoylphosphatidylethanolamine (DOPE) as a molar ratio of 1:2:3. The liposomes were not observed to have cytotoxicity for human glioma cells, when applied at a rate less than 15nmol/ml. This liposome-mediated transfection of the gene into the cultured glioma cells (U-251-MG) resulted in the secretion of HuIFN- beta into the medium. The HuIFN- beta level in the culture media of glioma cells reached 23 IU/ml after 96h of incubation. When the pSV2IFN-beta containing liposomes were coupled with a monoclonal antibody (G-22 MCA) against glioma-associated antigen (G-22), the level of HuIFN-beta in the medium was 181 IU/ml, resulting in a 7-fold increase. It was indicated that this transfection system was a safe and selective method in the case of TMAG/DLPC/DOPE liposomes.

Brain Neoplasms↗
PubMed1991

Sino-aortic baroreceptors are not involved in the potentiation of vasopressin or oxytocin secretion observed after noxious stimuli in the rat.

The possibility that arterial baroreceptors may be involved in the potentiation of vasopressin or oxytocin secretion observed after noxious stimuli was tested in male rats after sino-aortic denervation (SAD). There was no significant difference in plasma level of vasopressin or oxytocin between the SAD and the corresponding sham-operation control (SHAM) groups with or without electric shocks. An i.p. injected alpha 1-adrenergic receptor antagonist, prazosin, decreased arterial blood pressure both in the SAD and in the SHAM groups. However, the increased levels of these hormones after prazosin were significantly lower in the SAD than in the SHAM groups. Reflexly evoked tachycardia after prazosin occurred in the SHAM but not in the SAD groups. These results suggest that afferent neural signals originating from arterial baroreceptors are not involved in potentiation of vasopressin and oxytocin secretion after noxious stimuli in the rat.

Animals↗
PubMed1991

ATP diphosphohydrolase is responsible for ecto-ATPase and ecto-ADPase activities in bovine aorta endothelial and smooth muscle cells.

An ATP diphosphohydrolase (EC 3.6.1.5) is an enzyme hydrolyzing pyrophosphate bonds in nucleoside di- and triphosphates with broad substrate specificity in the presence of divalent cations. The ATPase and ADPase activities in the enzyme purified to homogeneity from bovine aortic vessel wall were insensitive to oligomycin, ouabain, and various protease treatments, and sensitive to azide and Ap5A. Bovine aorta endothelial and smooth muscle cells were cultured separately to characterize the ectonucleotidase activities. The activities were dependent on the addition of divalent cations and had broad substrate specificity. The ecto-ATPase and -ADPase activities were insensitive to oligomycin, ouabain, and protease treatments, and sensitive to azide and Ap5A. No enzyme degrading only ADP was found in the aortic vessel wall. Moreover, antiserum raised against purified ATP diphosphohydrolase inhibited the ecto-ATPase and -ADPase activities. These results indicated that ecto-ATPase and ecto-ADPase are not separate enzymes but are expressed by one enzyme, ATP diphosphohydrolase.

Adenine Nucleotides↗
PubMed1991

Expression in monkey cells of the missing enzyme in L-ascorbic acid biosynthesis, L-gulono-gamma-lactone oxidase.

L-Gulono-gamma-lactone oxidase (GLO), an enzyme that is missing in scurvy-prone animals, was produced in COS-1 cells by transfection with a minigene constructed from pSVL vector and rat GLO cDNA. A functional GLO protein was expressed, which was indistinguishable from rat GLO in molecular size. The microsomes obtained from the transfected COS-1 cells showed GLO activity comparable to that in rat liver microsomes.

Animals↗
PubMed1991

Structurally different rat liver medium-chain acyl CoA dehydrogenases directed by complementary DNAs differing in their 5'-region.

Different forms of rat liver medium-chain acyl CoA dehydrogenase (MCAD) (EC 1.3.99.3) were produced in Escherichia coli carrying expression plasmids (pRMCADm-1 approximately 9) differing at the 5'-region of the cDNA. The proteins expressed could be readily extracted from the cells. The protein (approximately 44 kDa) directed by pRMCADm-3 showed the highest activity and was readily purified to homogeneity. The purified enzyme contained non-covalently bound FAD and was similar to rat liver mitochondrial enzyme in all respects examined. The purified protein (approximately 45 kDa) directed by pRMCADm-1 did not contain FAD and showed no enzymatic activity. Therefore, the leader peptide disturbs the binding of FAD to the apoprotein. The purified protein (approximately 40 kDa) directed by pRMCADm-6 did not contain FAD. Thus, the deletion of the NH2-terminal portion of the apoprotein to some extent results in its inability to combine with FAD.

Acyl-CoA Dehydrogenase↗
PubMed1991

In vitro reappraisal of the pulmonary artery catheter balloon volume-pressure relationship: comparison of four different catheters.

The most serious risk of the use of the flow-directed pulmonary artery (PA) catheter is PA rupture due to high balloon inflation pressure of the catheter. Previously reported measurements of PA catheter intra-balloon pressure and volume during balloon inflation were performed mostly in a static fashion, that is, measurements were performed after a certain volume of air had been injected into the balloon. In this study, simultaneous measurements of pressure and volume, in addition to a static study, were performed in vitro using four PA catheters (Abbott Opticath, Arrow Hands-Off, Baxter Edwards and Spectramed). The peak intra-balloon pressure was recorded immediately before loss of resistance was felt in the inflating syringe. Contrary to previously reported studies, the peak intra-balloon pressure was not the pressure exerted on the pulmonary artery wall unless the tip of the catheter was already in the peripheral pulmonary artery. The loss of resistance volume which was constant for each catheter could be used reliably as an indicator of instantaneous balloon inflation. The slower the rate of injection, the lower were the peak pressure and the injection volume at the peak pressure. The Abbott, Edwards and Spectramed catheters had similar characteristics of inflation volume and intra-balloon pressure. The Arrow catheter had higher balloon opening and plateau pressures, and a smaller balloon volume compared with the other three catheters.

Analysis of Variance↗
PubMed1991

Limited value of delayed radiothallium image in the diagnosis of nodular goiter.

To test whether delayed thallium image can improve the diagnostic accuracy of thyroid tumor, we have reviewed 35 patients with cold nodules of proven histopathology. Early and delayed images were taken 10-20 min and 3-4 hr postinjection, respectively. In this study, a thyroid nodule was interpreted as malignant if it had normal or increased uptake on early scan and more residual radioactivity than paranodular tissue on delayed scan. In the eighteen patients who had carcinoma, a disappointing 44% false negative rate was observed. No significant difference was seen between retention-positive and negative cases in tumor size or histological type of cancer. Nor could any demographic bias explain the low sensitivity. Of the six false negatives, macroscopic cystic degeneration was seen in two cases, but tumors in the other four were grossly solid. Considering the histological heterogeneity often seen within a thyroid tumor, the portion with increased retention of radiothallium may be too small to be detected in the false negative cases. Furthermore, 3 false positive readings were obtained in 17 patients with benign conditions. We conclude that the contribution of the delayed thallium image was quite limited in predicting or ruling out malignancy in nodular goiters.

Adult↗
PubMed1991

Effect of linoleic acid hydroperoxide on replication of adenovirus DNA in endothelial cells of bovine aorta.

The effect of linoleic acid hydroperoxide on replication of adenovirus type 2 DNA in cultured endothelial cells of bovine aorta was studied to elucidate the deleterious effect of lipid peroxides on replication of DNA in the arterial endothelial cells. When, just after the infection, the cells were incubated with 1 nmol (measured by the thiobarbituric acid reaction and expressed in terms of malondialdehyde) of the hydroperoxide, the replication of adenovirus type 2 DNA was markedly reduced. The level of the messenger RNA for adenovirus type 2 DNA polymerase was also reduced. In accordance with the reduction of the messenger RNA, the synthesis of the polymerase in the cells was reduced. The inhibition of DNA replication in the arterial endothelial cells by lipid peroxides was discussed in relation to atherogenesis.

Adenoviruses, Human↗
PubMed1991

Serum lipoprotein lipid concentration and composition in homozygous and heterozygous patients with cholesteryl ester transfer protein deficiency.

Six homozygous, 10 heterozygous and 8 unaffected subjects in a CETP deficient family confirmed by CETP gene analysis were studied to characterize serum lipoproteins separated by ultracentrifugation, and to examine the relations between CETP levels and lipoprotein lipid concentration and composition. The serum CETP levels were measured by radioimmunoassay using 125I-labeled monoclonal antibodies (TP2). The serum CETP levels in the homozygotes were undetectable and those in the heterozygotes were significantly lower than those in the unaffected subjects (1.5 +/- 0.1 vs. 2.2 +/- 0.5 microgram/ml, P less than 0.01). In the HDL fraction, esterified cholesterol (EC) levels in the homozygotes were significantly increased (P less than 0.01), and those in the heterozygotes were slightly increased (n.s.), in comparison with those in the unaffected and the normolipidemic controls. The EC levels in the IDL fractions were lower in the homozygotes than in the normolipidemic controls. The EC/triglyceride (TG) molar ratios in IDL, the fraction obtained from the homo- and heterozygotes, were lower than those from the unaffected subjects (P less than 0.01 and less than 0.01, respectively), and the EC/TG ratios in the HDL fraction obtained from the homo- and heterozygotes were higher than those from the unaffected subjects (P less than 0.01 and n.s., respectively). Linear regression analysis showed that positive correlates of the serum CETP levels in all subjects were: IDL-EC (r = 0.463), HDL-TG (r = 0.603) and VLDL- and IDL-EC/TG ratio (r = 0.698 and 0.843).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Molecular basis for the deficiency in humans of gulonolactone oxidase, a key enzyme for ascorbic acid biosynthesis.

The inability of humans to synthesize L-ascorbic acid is known to be due to a lack of L-gulono-gamma-lactone oxidase, an enzyme that is required for the biosynthesis of this vitamin. Isolation of a cDNA for rat L-gulono-gamma-lactone oxidase allowed us to study the basic defect underlying this deficiency at the gene level and led to isolation of a human genomic clone related to L-gulono-gamma-lactone oxidase as well as three overlapping clones covering the entire coding region of the rat L-gulono-gamma-lactone oxidase cDNA. Sequence analysis study indicated that the human L-gulono-gamma-lactone oxidase gene has accumulated a large number of mutations since it stopped being active and that it now exists as a pseudogene in the human genome.

Ascorbic Acid↗
PubMed1991

A site-directed mutagenesis study of yeast calmodulin.

A site-directed mutagenesis study was carried out in order to understand the regulatory mechanism of calmodulin. We started from the yeast (Saccharomyces cerevisiae) calmodulin gene since it has many differences in amino acid sequence and inferior functional properties compared with the vertebrate calmodulin. Recombinant yeast calmodulins were generated in Escherichia coli transformed by constructed expression plasmids. Three recombinant calmodulins were obtained. The first two were YCM61G, in which the Ca2(+)-binding site 2 (the four Ca2(+)-binding EF-hand structures in calmodulin were numbered from the N-terminus) was converted to the same as that in vertebrate calmodulin, and YCM delta 132-148, in which the C-terminal half sequence of site 4 was deleted. These two recombinant calmodulins had the same maximum Ca2+ binding (3 mol/mol) as yeast calmodulin, which indicates that site 4 of yeast calmodulin was the one losing Ca2+ binding capacity. YCM delta 132-148 could not activate target enzymes, whereas its Ca2+ binding profile was similar to those of yeast calmodulin and YCM61G. Therefore, the structure in site 4 which cannot bind Ca2+ is indispensable for the regulatory function of yeast calmodulin. The complete regulatory function of vertebrate calmodulin can be attained by the combination of 4 Ca2+ binding structures. The negative charge cluster in the central alpha-helix region is suggested to stabilize the active conformation of calmodulin, since the third yeast calmodulin mutant, YCM83E, which had the negative charge cluster, increased the maximum activation of myosin light chain kinase.

Amino Acid Sequence↗
PubMed1991

Monoclonal antibodies toward scallop (Patinopecten yessoensis) testis and wheat germ calmodulins.

A monoclonal antibody (IM7) toward scallop testis calmodulin and another one (PBE2) toward wheat germ calmodulin were produced. Ca2+ was required for IM7 to react with scallop calmodulin. IM7 reacted with the C-terminal region (Asp78-Lys148) of the calmodulin. As observed on competitive ELISA, IM7 reacted with chicken calmodulin, but not with Euglena gracilis or wheat calmodulin, troponin C, myosin light chains, or parvalbumin. It is assumed that the cluster of Thr143, Thr146, and Ser147 in the C-terminal region acts as the antigenic site. IM7 (and Fab of IM7) inhibited the activities of myosin light chain kinase and cAMP-phosphodiesterase. PBE2 reacted with wheat germ calmodulin irrespective of the presence or absence of Ca2+, the antigenic site being in the N-terminal region (Ala1-Met37). It reacted with wheat and spinach calmodulins, but not with scallop, chicken, or Euglena calmodulin, troponin C, myosin light chains, or parvalbumin. PBE2 had no effect on the activities of myosin light chain kinase and cAMP-phosphodiesterase.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1991

Mastoparan binding induces Ca(2+)-transfer between two globular domains of calmodulin: a 1H NMR study.

The interaction between calmodulin and mastoparan at various concentrations of calcium ions was studied by 1H NMR. It was found that at lower mastoparan concentrations 1 mol of mastoparan binds to both the C-terminal-half and N-terminal-half regions of calcium-saturated calmodulin. The mastoparan affinity is much greater for the C-terminal-half region than for the N-terminal-half region. At higher mastoparan concentrations, a further 1 mol of mastoparan binds to the N-terminal-region of calcium saturated calmodulin. The results can be interpreted in terms of the assumption that the N-terminal-half region of calmodulin with mastoparan has a higher calcium ion affinity than the C-terminal-half region without mastoparan. It is suggested that calcium ions transfer from the C-terminal-half region of calmodulin without mastoparan to the N-terminal-half region of calmodulin with mastoparan. This calcium ion transfer is discussed from the viewpoint of enzyme activation by calmodulin.

Amino Acid Sequence↗
PubMed1991

Epilepsy associated with hemiplegia: 1. Seizure manifestations.

1. The seizure manifestations of patients with hemiplegia were reminiscent of partial seizures. The motor manifestations were notably asymmetrical and impairment of consciousness was mild. Nevertheless, tonic seizures, identified by electroclinical correlation were found in 49 patients (88%) although they were predominantly unilateral or asymmetrical. 2. Unclassified seizures characterized by ictal automatisms, which mimic complex partial seizures was observed in 5 patients (9%). 3. Late epileptic seizures of the HHE syndrome were regarded as psychomotor seizures by Gastaut et al. In the present study, however, complex partial seizures were found in only 3 at 28 patients with HHE syndrome (11%) whereas tonic seizures in 23 of these patients (82%). One possible reason for this discrepancy is bias in the selected patient population, because those with transient hemiplegia were not included, and infrequently occurring partial seizures might have been missed. Further study is therefore needed to determine whether the HHE syndrome is associated with complex partial seizures or predominantly unilateral tonic seizures.

Cerebral Cortex↗