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Biomedical subjects

K Okuda

Publications and source records attributed to K Okuda.

At least 307 records · Page 17Linked to original sources
PubMed1996

Absence of imprinting in U2AFBPL, a human homologue of the imprinted mouse gene U2afbp-rs.

The mouse gene U2 auxiliary factor binding protein related sequence (U2afbp-rs) has previously been shown to be genomically imprinted with monoallelic expression from the paternal allele. To determine if the human homologue is imprinted and contains conserved structural features which regulate imprinting, we isolated genomic clones from a human P1-derived artificial chromosome (PAC) library that map to human chromosome 5q22-31, a region syntenic to the proximal portion of mouse chromosome 11 where U2afbp-rs resides. A genomic subclone was isolated which contained an open reading frame with high homology to the mouse gene. This subclone also maintained the intronless character of the mouse gene. A KpnI polymorphism within the open reading frame of the gene was found to occur in 21% (8/38) of the alleles tested from human placental tissue samples. RT-PCR analysis of human placentas using the KpnI polymorphism to determine the parental origin of the alleles indicates biallelic expression of the human chromosome 5 U2AFBPL gene.

Alleles↗
PubMed1996

The proto-oncogene product p120CBL and the adaptor proteins CRKL and c-CRK link c-ABL, p190BCR/ABL and p210BCR/ABL to the phosphatidylinositol-3' kinase pathway.

Chronic myelogenous leukemia (CML) and some acute lymphoblastic leukemias (ALL) are caused by the t(9;22) chromosome translocation, which produces the constitutively activated BCR/ABL tyrosine kinase. When introduced into factor dependent hematopoietic cell lines, BCR/ABL induces the tyrosine phosphorylation of many cellular proteins. One prominent BCR/ABL substrate is p120CBL, the cellular homolog of the v-Cbl oncoprotein. In an effort to understand the possible contribution of p120CBL to transformation by BCR/ABL, we looked for cellular proteins which associate with p120CBL in hematopoietic cell lines transformed by BCR/ABL. In addition to p210BCR/ABL and c-ABL, p120CBL coprecipitated with an 85 kDa phosphoprotein, which was identified as the p85 subunit of PI3K. Anti-p120CBL immunoprecipitates from BCR/ABL-transformed, but not from untransformed, cell lines contained PI3K lipid kinase activity. Interestingly, the adaptor proteins CRKL and c-CRK were also found in these complexes. In vitro binding studies indicated that the SH2 domains of CRKL and c-CRK bound directly to p120CBL, while the SH3 domains of c-CRK and CRKL bound to BCR/ABL and c-ABL. The N-terminal and the C-terminal SH2 and the SH3 domain of p85PI3K bound directly in vitro to p120CBL. The ABL-SH2, but not ABL-SH3, could also bind to p120CBL. These data suggest that BCR/ABL may induce the formation of multimeric complexes of signaling proteins which include p120CBL, PI3K, c-CRK or CRKL, c-ABL and BCR/ABL itself.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Induction of HIV-1 Nef-specific cytotoxic T lymphocytes by Nef-expressing DNA vaccine.

Recently, some individuals who have remained seronegative despite definite exposure to HIV-1 have been reported. Among these individuals, an unusually high frequency of HIV-1 Nef-specific cytotoxic T lymphocytes was observed. Direct injection of plasmid DNA encoding foreign antigen can elicit both cell-mediated immunity and antibody responses (DNA vaccine). We constructed an HIV-1 Nef-expressing plasmid, and we induced HIV-1 Nef-specific cytotoxic T lymphocytes. This is the first report of inducing HIV-1 Nef-specific cytotoxic T lymphocytes by DNA vaccine.

Amino Acid Sequence↗
PubMed1996

The long-term pathological evolution of chronic hepatitis C.

Most patients infected with hepatitis C virus (HCV) develop chronic hepatitis. Unfortunately, the pathological evolution of this disease over time is not completely understood. We studied 70 HCV-positive patients, from whom 2 to 10 liver biopsy specimens (mean, 3.9) had been obtained during an interval of 1 to 26 years (mean, 8.8 years). Each biopsy specimen was evaluated independently by four pathologists who each provided a numerical score for the grade of portal/periportal necroinflammation (0-4), grade of lobular necroinflammation (0-4), their sum (final grade), and the stage of fibrosis (1-4). The scores were correlated with progression of disease, if any, and transition to cirrhosis. During follow-up, 35 patients (50%) developed cirrhosis. Cirrhosis developed in all patients with a high final grade (> or = 5) of necroinflammation on initial biopsy who were followed for 10 years and in 96% of patients with an intermediate final grade (3.5-4.9) who were followed for 17 years. Only 30.4% of patients with low final grade (< or = 3.4) on initial biopsy developed cirrhosis after 13 years. All patients with evidence of septal fibrosis with incomplete nodularity (stage 3.0-3.4) in the initial biopsy progressed to unequivocal cirrhosis by 10 years. The rate of progression to cirrhosis was accelerated in patients whose initial biopsies showed high-grade and -stage lesions. This study demonstrates the importance of grading and staging liver biopsy lesions in chronic hepatitis C, particularly for patients with high-grade necroinflammation, septal fibrosis, and regions of modularity on initial biopsy who are at high risk of developing advanced cirrhosis in the ensuing decade.

Biopsy↗
PubMed1996

Genetic control of in vivo tumor necrosis factor production in mice.

We report on the genetic effect on in vivo production of tumor necrosis factor (TNF)-alpha induced by lipopolysaccharides (LPS) using various congenic mouse strains. B10.A, Bl0.A(3R), B10.AQR, B10.A(5R), and B10.S(7R) produced significantly high TNF-alpha compared with B10.BR, B10.S, C57BL/10, B10.A(2R), B10.A(4R), B10.G, B10.DA(80NS), and B10.RIII(71NS). This suggests that LPS-induced TNF-alpha production is genetically controlled by H-2. Mice with the same alleles on K, A, E, or S loci produced various (high or low) levels of TNF-alpha, thus indicating that regulatory genes are located outside these loci. All strains with H-2Dd produced significantly high levels of TNF-alpha, but strains with other alleles in the H-2D locus produced low levels. Thus, TNF-alpha production appears to be genetically linked to H-2D itself or H-2D linked genes and the allele d is linked to a high responder gene. This was the case with the A background. C3H/HeN (H-2k), however, showed a high TNF-alpha production, suggesting the presence of another controlling gene outside H-2. In addition, high TNF-alpha productivity was transmitted into F1 mice (B10.A X B10.BR) in a dominant fashion. Both LPS-stimulated and unstimulated TNF-alpha mRNA expression in splenic macrophages were enhanced in high responder strains. Thus, we conclude that TNF-alpha production is closely related to genes within or linked to the H-2D locus as well as others outside H-2.

Animals↗
PubMed1996

Comparative study of 201Tl-scintigraphic image and myocardial pathologic findings in patients with dilated cardiomyopathy.

The objective of the present study was to characterize the production of 201Tl myocardial perfusion defects, the relation between the 201Tl multiple small defects and the myocardial damage indicated by myocardial fibrosis shown histopathologically in patients with dilated cardiomyopathy (DCM). Rest 201Tl scintigraphy was performed in thirty-seven patients with myocardial tissue fibrosis by endomyocardial biopsy, and without stenosis of the coronary artery. 201Tl myocardial SPECT images were visually classified into 4 grades according to the severity of inhomogeneous perfusion defects (IPD), 0: none, 1: slight, 2: moderate, 3: severe. 201Tl uptake, defect regions (DR), and coefficient of variation % (CV%) were also quantified by Bull's eye quantification in nineteen patients. During cardiac catheterization, three biopsy specimens were obtained from the lateral wall to the apical region of the left ventricle and the amount of fibrosis was assessed by means of light microscopic morphometry. The myocardial fibrosis was also classified into 4 grades by a point-counting method. Autopsy study was also assessed in six patients. 201Tl perfusion defects were observed in 35 (94.6%) patients, of whom 29 (78.4%) showed inhomogeneous perfusion defects. Twenty-four (64.9%) showed Stage 0 and 201Tl findings, and 21 (62.2%) had myocardial fibrosis in stage 1. Clinically, the correlation between the grades of the IPD, % 201Tl uptake, DR and CV% of myocardial uptake, which were calculated semiquantitatively by Bull's eye image, and the histological grades of fibrosis were also good (IPD vs. fibrosis: r = 0.7014; % 201Tl uptake vs. fibrosis: r = -0.6542; DR vs. fibrosis: r = 0.7027; CV% vs. fibrosis: r = 0.6985). The 201Tl SPECT findings were in close agreement with the severity of myocardial fibrosis confirmed by autopsy, but the grading of the IPD was not related to the ejection fraction or left ventricular diameter. It showed a higher rate of inhomogeneous 201Tl myocardial perfusion defects (78.4%) in patients with DCM. This result may contribute to the clinical evaluation of DCM or differentiation from other diseases. Furthermore, the grading of 201Tl inhomogeneous perfusion defects related to the myocardial fibrosis of left ventricular myocardium may contribute to speculation of the myocardial degenerative stage in clinical settings.

Adult↗
PubMed1996

Limitation of infarct size with preconditioning and calcium antagonist (diltiazem): difference in 99mTc-PYP uptake in the myocardium.

UNLABELLED: Ischemic cell injury and the uptake mechanism of 99mTc-PYP (Pyrophosphate) were studied with preconditioning and calcium antagonist. METHOD: The coronary artery of an adult mongrel dog was clamped for 1 hour, followed by reperfusion and 99mTc-PYP injection. A control group (group C, n = 8), a group in which continuous drip infusion of diltiazem (10 mg/kg) (group D, n = 7), and a group preconditioned by six 5-minute clampings and perfusions before occlusion (group P, n = 6) were compared. RESULTS: Wall motion was fully recovered in group D but not in group P after 2 hours of reperfusion. The 99mTc-PYP uptake ratio showed a significant (p < 0.05) reduction in group D (11.5 : 3.6 compared with group C), but not in group P (11.5 : 9.1, p = 0.25). The infarct area was 1.2 +/- 0.6% of the left ventricle in group D, 1.3 +/- 0.4 in group P, and 6.4 +/- 1.0 in group C (p < 0.01 in groups D and P vs. group C). CONCLUSIONS: These findings suggest that preconditioning does not alleviate stunning, but it improves cell injury in spite of high uptake of 99mTc-PYP. Diltiazem protects from both stunning and cell injury, suggesting a different mechanism of myocardial protection from that of preconditioning.

Animals↗
PubMed1996

Interleukin-6 (IL-6) in patients with Behçet's disease.

We have examined the levels of interleukin-6 (IL-6) in plasma and supernatants of peripheral blood mononuclear cells (PBMC) from patients with Behçet's disease and healthy controls using a sensitive enzyme-linked immunosorbent assay (ELISA). Plasma IL-6 level was not detected in any subjects. The IL-6 concentrations in culture supernatants of patients with active Behçet's disease were significantly high compared with patients with inactive disease and healthy controls. Moreover, we investigated IL-6 gene expression in cultured PBMC from patients with Behçet's disease. IL-6 gene expression was enhanced in active patients compared with inactive patients. These results show that IL-6 may play a role in the pathogenesis of Behçet's disease.

Adult↗
PubMed1996

An antibody to a 17 amino acid synthetic peptide of the type I interleukin-1 receptor preferentially blocks interleukin-1 beta binding.

On the basis of their relative hydropathy and alpha-helical structure, we prepared antibodies to four synthetic peptides with amino acid sequences homolgous to four hydrophilic, extracellular regions of the murine 80 kDa type I interleukin-1 receptor (IL-1RI). Antibodies to each of the four peptides recognized their specific immunogen. Human [125I]-IL-1 alpha or -beta was crosslinked to murine EL4 and D10S cells. Antiserum to peptide 150-166 precipitated the IL-1/IL-1R complex, whereas antibodies to peptide 66-84, 190-200, or 266-285 did not. Antibody to peptide 150-166 did not precipitate the type II IL-1R. Anti-IL-1RI150-166 blocked 71% of the binding of radiolabeled human IL-1 beta to EL4 cells and 50% of the binding to D10S cells. Using affinity-purified anti-IL-1RI150-166, we compared the ability of this antibody to inhibit the binding of murine or human IL-1 alpha to that of murine or human IL-1 beta. At a concentration of 20 ng/ml, affinity-purified anti-IL-1RI150-166 blocked 50% binding of murine IL-1 beta. At 1 microgram/ml, 90% blockage was observed. In contrast, no significant blockade of IL-1 alpha binding was observed at concentrations as high as 3 micrograms/ml of anti-IL-1RI150-166. The selective blockade of IL-1 beta forms was not due to differences in the affinities of these ligands for receptors on these cells. The antibody also blocked the binding of human IL-1 beta but not human IL-1 alpha to EL4 cells. The biologic activity of murine IL-1 beta but not IL-1 alpha on EL4 cells was also inhibited by this antibody. These data suggest (1) that antibody to a specific epitope on the extracellular domain interferes with the binding of IL-1 beta but not IL-1 alpha, (2) the differential inhibition of binding of IL-1 beta but not IL-1 alpha by anti-IL-1RI150-166 also blocks biologic activity, and (3) IL-1 alpha and IL-1 beta may transduce different signals by binding to separate loci on the IL-1RI.

Amino Acid Sequence↗
PubMed1996

Dysfunction of the Orleans reeler gene arising from exon skipping due to transposition of a full-length copy of an active L1 sequence into the skipped exon.

We examined the genomic structure of the reeler gene in Orleans reeler mouse mutant. Exon skipping of the reeler gene caused a 220 bp deletion in the transcript, resulting in a frame shift of the reeler gene which disrupts the 8th EGF-like motif of the reeler product. Surprisingly, the skipped exon was inserted by the 7104 bp L1 element which carried the full-length stretch of the mouse L1 sequence, consisting of a 212 bp F-type tandem repeat, open reading frame 1 (ORF1), ORF2, the polyadenylation signal and a poly A stretch. The transposed L1 sequence was flanked by 13 bp of the target sequence at both ends. ORF1 and ORF2 of this L1 repeat element are thought to encode a component of the RNP particle and the reverse transcriptase, respectively. Orleans reeler was originally established by spontaneous mutation caused by L1 insertion, and this L1 sequence is considered to be potentially active for transposition in mouse genome.

Amino Acid Sequence↗
PubMed1996

Characterization of Actinobacillus actinomycetemcomitans hemolysin.

Twenty out of 33 Actinobacillus actinomycetemcomitans strains formed hemolytic colonies on horse blood agar plates under anaerobic conditions. The hemolytic activity found in A. actinomycetemcomitans strain 137HE was examined. This activity was detected in the late exponential to early stationary phases of growth. Human erythrocytes were the most susceptible, followed by rabbit, sheep, horse and swine red blood cells. The majority of activity was detected in the cell-associated vesicle fraction. Zwitterionic detergent 3-[(3-cholamidopropyl)-dimethyl-ammonio]-1-propanesulfonate (CHAPS) extract from whole cells was semipurified by ammonium sulfate precipitation, preparative isoelectric focusing (IEF) and gel-filtration chromatography to yield a major band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with a molecular mass of 12 kDa. Heating at 80 C for 30 min and treatment with proteinase K or trypsin resulted in complete disappearance of the hemolytic activity. Sulphydryl reagents enhanced activity and small amounts of cholesterol inhibited it. In summary, we demonstrated the presence of hemolysin in A. actinomycetemcomitans, and examined and characterized it.

Aggregatibacter actinomycetemcomitans↗
PubMed1996

Treatment of gastric fundal varices by balloon-occluded retrograde transvenous obliteration.

Although less common than oesophageal varices in portal hypertension, gastric fundal varices carry a higher mortality rate when they rupture. They are less amenable to sclerotherapy. We have developed a minimally invasive balloon-occluded retrograde transverse obliteration (B-RTO) procedure to treat gastric fundal varices. B-RTO involves inserting a balloon catheter into an outflow shunt (gastric-renal or gastric-vena caval inferior) via the femoral or internal jugular vein. Blood flow is then blocked by inflating the balloon, and 5% ethanolamine oleate iopamidol is injected in a retrograde manner. The embolized gastric varix subsequently disappears. B-RTO was performed in 32 patients with gastric varices. Follow-up endoscopies were performed at intervals of 2-4 months for an average observation period of 14 months. Eradication of the varices has been confirmed in 31 of 32 patients. No recurrence occurred in any patients in the follow-up period. There were no significant changes in liver function after the procedure. We conclude that B-RTO is a safe and effective procedure for the treatment of gastric fundal varices.

Adult↗
PubMed1996

Endemicity and clinical picture of liver disease due to obstruction of the hepatic portion of the inferior vena cava in Nepal.

Obstructive lesion of the hepatic portion of the inferior vena cava is common in Nepal. The clinical data on 150 patients who were seen at the Liver Unit, Bir Hospital, Kathmandu, in three years from 1990 to 1992 were analysed. Although the majority of patients were over 20 years of age, 25 patients were below 10 years of age; there were more males than females in this study. This disease accounted for 17% of 866 patients with chronic liver disease and for nearly one quarter of 267 biopsies performed on this patient group during the same period. Obstructive lesions of the inferior vena cava seem to be more common among poor people with malnutrition. Clinically, our patient group could be divided into acute (n = 27), subacute (n = 43) and chronic (n = 80) cases. The important clinical features are hepatomegaly and/or ascites and, in chronic cases, prominent dilated superficial veins over the body trunk with cephalad flow. Ultrasound is the most helpful diagnostic procedure, especially in subacute and chronic cases, as it frequently demonstrates caval obstruction, thrombosis, dilated hepatic veins and intrahepatic collaterals. Diagnosis is confirmed by cavography, which shows a caval obstruction of varying lengths at the cavo-atrial junction or a marked narrowing of the hepatic portion of the vena cava. In subacute and chronic cases cavography also demonstrates collateral veins, such as the ascending lumbar, hemiazygos and azygos that drain into the superior vena cava. Chronic cases had periods of exacerbation often associated with bacterial infection. The aetiology of inferior vena cava obstruction at its hepatic portion is not known, but there seems to be a frequent association of bacterial infection with the disease.

Acute Disease↗
PubMed1996

Characterization of the Treponema denticola prtP gene encoding a prolyl-phenylalanine-specific protease (dentilisin).

A chymotrypsin-like protease from Treponema denticola ATCC 35405 was purified by chromatographic techniques. The purified enzyme consisted of three polypeptides (38, 43, and 72 kDa). The protease exhibited specificity for peptide bonds containing phenylalanine and proline at the P1 and P2 positions, respectively, and was classified as a serine protease on the basis of inhibition studies. Naturally occurring protease inhibitors such as alpha1-antitrypsin and alpha1-antichymotrypsin had no effect on enzymatic activity. The enzyme degraded fibronectin, alpha1-antitrypsin, and gelatin while weakly degrading the immunoglobulin G heavy chain and type IV collagen. N-terminal amino acid sequences were determined for the 43- and 72-kDa proteins. On the basis of these sequences, the genes coding for the 43- and 72-kDa proteins were isolated and sequenced. The open reading frame which codes for the 72-kDa protein was designated prtP. This gene consists of 2,169 bp and codes for a protein with an Mr of 77,471. The protein appeared to be composed of a signal peptide region followed by a prosequence and the mature protein domain. The deduced amino acid sequence exhibited similarity with that of the Bacillus subtilis serine protease subtilisin. The deduced properties of the sequence suggest that the 72-kDa protein is a chymotrypsin-like protease. However, the nature and function of the 43-kDa protein have not yet been determined.

Amino Acid Sequence↗
PubMed1996

Inhibitory effects of funoran on the adherence and colonization of mutans streptococci.

Funoran, a sulfated polysaccharide extracted from the seaweed Gloiopeltis furcata strongly inhibited the absorption of mutans streptococci to saliva-coated hydroxyapatite (S-HA), but enhanced that of Streptococcus sanguis ATCC 10556 and Streptococcus oralis ATCC 10557. Furthermore, funoran had a strong desorption activity against mutans streptococci preadsorbed to S-HA. In the presence of sucrose, the absorption of cells of Streptococcus sobrinus B13, Streptococcus mutans Ingbritt, and S. mutans MT8148R to S-HA was strongly inhibited by 0.01% funoran. The colonization of S. sobrinus 6715 inoculated on the molar teeth of experimental rats that were administered funoran was less frequent than that in a funoran-free group. The mean buccal and lingual, sulcal, and total caries scores of rat groups administered funoran were significantly lower than those of the funoran-free group.

Adsorption↗
PubMed1996

Immunohistochemically-determined changes in the distribution of insulin-like growth factor-I (IGF-I) and epidermal growth factor (EGF) in the bovine endometrium during the estrous cycle.

The aims of this study were to investigate whether there are cell-specific distributions of insulin-like growth factor I (IGF-I) and epidermal growth factor (EGF) in the endometrium, and to determine whether or not the expression of these factors varies with the stage of the estrous cycle. Fifty-four endometrial biopsy specimens were collected from normal cycle Holstein-Friesian heifers. The endometrial specimens were divided into nine groups (at least five different animals per group) corresponding to the following days of the cycle: days 20-0, 1-3, 4-5, 6-7, 8-10, 11-13, 14-15, 16-17, and 18-19 (day 0 = estrus). IGF-I and EGF were localized by immunohistochemistry in the intact heifer endometrium throughout the estrous cycle. Throughout the estrous cycle, IGF-I was localized in the luminal epithelium and stroma with a little staining in the glandular epithelium (P < 0.01). In the luminal epithelium, the number of IGF-I-positive cells increased on days 1-3, 6-7, 11-13, and 16-17. In the stroma, the number of IGF-I-positive cells increased on days 8-10 and 20-3. The number of positively stained cells in the glandular epithelium increased around the estrous period. EGF stained intensely in the stroma but very little in the luminal and glandular epithelia (P < 0.01). In the stroma, three peaks in the number of EGF-positive cells were observed: on days 1-3, 6-7, and 11-13. These results demonstrate cyclical changes in the endometrial cell types localization of IGF-I and EGF.

Animals↗