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Biomedical subjects

K Okuda

Publications and source records attributed to K Okuda.

At least 433 records · Page 24Linked to original sources
PubMed1994

Bacteriological diagnosis of periodontal disease.

Dental plaque bacteria cause virtually all the forms of inflammatory periodontal disease. Periodontitis is caused by the specific periodontopathic bacteria, which induce destruction of connective tissue attachment and adjacent alveolar bone. Examinations to identify the infections by Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Prevotella intermedia, Campylobacter rectus, Bacteroides forsythus, Fusobacterium nucleatum, Eikenella corrodens and Treponema denticola have recently become essential in diagnosis of periodontal disease. Bacterial examination permits (1) identification of the causative bacteria, (2) assessment of disease activity and (3) monitoring of the effective of periodontal treatments. The author describes details of accurate and rapid methods for detecting periodontopathogens. Transmission of periodontopathic bacteria as clarified by bacterial examination is also discussed in this review. The pathogenic potential of specific bacteria varies among patients and periodontally healthy individuals and can be controlled by host defense mechanisms such as immune responses. The roles of immune responses against periodontopathic bacteria in balance shifts of periodontal disease processes are therefore also discussed in this review.

Antibodies, Bacterial↗
PubMed1994

Coaggregation between Porphyromonas gingivalis and Treponema denticola.

To elucidate an ecological profile of several periodontopathogens, the authors examined the coaggregation between cells of Porphyromonas gingivalis and oral bacterial strains including Treponema denticola in vitro. Coaggregation between cells of plaque bacteria was examined by visual assay and phase-contrast microscope. P. gingivalis cells coaggregated with strains of T. denticola and Treponema socranskii subspecies socranskii, but did not coaggregate with T. socranskii subspecies buccale, T. socranskii subspecies paredis, Treponema vincentii, or Treponema pectinovorum. The extracted hemagglutinin from P. gingivalis was active agglutinating T. denticola cells. Addition of serum and saliva somewhat affected the coaggregation, but no effects of tested sugars or amino acids were found. Heat treatment of T. denticola cells did not reduce the coagregation: heat treatment of P. gingivalis cells eliminated it. Growth inhibitory activity among these bacterial species was examined by the stab culture method. Strains of T. denticola ATCC 35404 and 35405 and T. vincentii inhibited the growth of some P. gingivalis strains, but not others. No strain of Treponema was inhibited by black-pigmented anaerobic rods. The coaggregation observed between P. gingivalis and T. denticola indicates the potential importance of their simultaneous existence in human periodontal pockets and development of the disease.

Actinomyces↗
PubMed1994

Effect of initial therapy on dynamics of immunogloblin G levels to some periodontopathic bacteria in serum and gingival crevicular fluid.

Using enzyme-linked immunosorbent assay, the IgG antibody levels to specific gram-negative periodontopathic bacteria in serum of 21 adult periodontitis patients and the gingival crevicular fluid (GCF) from 42 sites with destructive lesions and 21 healthy sites were evaluated before and after initial preparation. Porphyromonas gingivalis, Bacteroides forsythus, Prevotella intermedia, Prevotella nigrescens, Campylobacter rectus, Treponema denticola and Actinobacillus actinomycetemcomitans in subgingival plaque samples from the patients were examined by indirect immunofluorescence microscopy. Subgingival plaque, GCF, and serum samples were taken at baseline and three weeks after initial preparation. For 14 patients, changes in clinical parameters due to the initial preparation were correlated with reduction of periodontopathogens and to IgG antibody levels in GCF and serum against them. P. gingivalis, T. denticola and C. rectus were found to be predominant in destructive sites. No significant differences were found in GCF IgG antibody levels between destructive and healthy sites. In destructive sites, the prevalence of P. gingivalis and C. rectus was significantly correlated with elevated IgG antibody against these microorganisms in GCF. The initial preparation resulted in significant reduction of serum IgG antibody levels against all microorganisms tested. No decrease in GCF IgG antibody was observed, but levels to P. gingivalis and C. rectus were significantly increased (p<0.05). The assessment of GCF IgG antibodies to specific periodontopathic bacteria may be of considerable value in reflecting the conditions of periodontitis.

Adult↗
PubMed1994

Detection of methicillin-resistant staphylococcus aureus in human saliva and on denture surfaces.

The prevalence of Staphylococcus species and methicillin-resistant Staphylococcus aureus (MRSA) in human saliva and on denture surfaces was examined with selective media. A total of 166 saliva samples from dental students and individuals using dentures and 39 swab samples from denture surfaces were subjected in this study. The detected percentage of MRSA from saliva samples was 2.3%. Five out of 39 swab samples of denture surface contained MRSA or methicillin-resistant Staphylococcus epidermidis (MRSE). The isolated MRSA and MRSE were resistant to beta-lactam antibiotics.

Adult↗
PubMed1993

Changes in amounts of cytochrome P450 isozymes and levels of catalytic activities in hepatic and renal microsomes of rats with streptozocin-induced diabetes.

Hepatic microsomal cytochrome P450s, which are involved in the metabolism of drugs, hormones, prostaglandins and fatty acids, change when animals develop diabetes. We studied changes in cytochrome P450 isozymes in both hepatic and renal microsomes of rats with diabetes caused by streptozocin, and compared the results with changes in catalytic activities in the microsomes. In hepatic microsomes of diabetic rats, the amount of cytochrome P450 2E1, an acetone-inducible isozyme, was two and a half times that of control rats, and that of P450 4A2, a major renal isozyme, was three times that in the controls. The amounts of cytochrome P450s 2A1, 2C6, 2C7, 3A2 and 4A3 increased in hepatic microsomes of diabetic rats, and P450 2C11 decreased. Treatment with insulin restored these to the levels in the controls. The catalytic activities of aniline hydroxylation, 7-ethoxycoumarin O-dealkylation, testosterone 2 beta, 6 beta, 7 alpha, and 16 beta-hydroxylation, and omega-, (omega-1)-hydroxylation of lauric acid were high in the hepatic microsomes of diabetic rats, and testosterone 2 alpha and 16 alpha-hydroxylation activities were low. In renal microsomes of diabetic rats, cytochrome P450s 2E1, 4A2 and K-4 were induced, and omega- and (omega-1)-hydroxylation activities were high. These changes were reversed by insulin treatment. The induction and suppression of cytochrome P450 isozymes in diabetic rats were consistent with the changes in the catalytic activities. In both hepatic and renal microsomes, P450s 2E1 and 4A2 were induced, altered metabolism of ketones and fatty acids in diabetes may contribute to these changes.

Animals↗
PubMed1993

Structural analysis of an extremely long 5'-noncoding region of rat brain argininosuccinate lyase mRNA: presence of multiple B1 repeats and multiple upstream AUG codons, and a possibility of translational control.

The present detailed analysis of the sequence of the extremely long (967 bp) 5'-noncoding region of a rat brain argininosuccinate lyase cDNA clone, reveals several features of interest. Multiple copies of partial and inverted (antisense) B1 repeats and multiple upstream ATG codons are present in the region, which suggests a possibility of translational control of the argininosuccinate lyase gene expression in rat brain.

Amino Acid Sequence↗
PubMed1993

Structure of the gene encoding human liver cholesterol 7 alpha-hydroxylase.

A human cholesterol 7 alpha-hydroxylase gene spanning 17 kb in length which includes the sequence 5' flanking region (6. kb) and that of the entire transcriptional region (10.5 kb) was obtained from two partially overlapping clones (i.e., HG 18 and HG 17) of a human genomic library. The exon-intron boundaries are completely identical with that of rat gene. Several transcriptional factor recognition sequences were observed in the 5' flanking region.

Amino Acid Sequence↗
PubMed1993

Structural characterization of the gene encoding rat 25-hydroxyvitamin D3 24-hydroxylase.

The structural gene encoding 25-hydroxyvitamin D3 24-hydroxylase (P-450cc24) was isolated from the rat genomic DNA. It spans approximately 15 kb, is composed of 12 exons, and was demonstrated by Southern blot analysis to be present as a single copy. One major T residue was identified at the cap site, a putative TATA (ATAAATA) box was located at position -30, and a putative CCAAT box was at -58. Four possible vitamin D responsive elements that may be involved in regulation of 24-hydroxylase expression were found in the 5'-flanking region. Alignment with mitochondrial P-450 proteins showed that 7 out of 11 intron insertion sites of P-450cc24 gene occupied positions identical with those in the CYP11 family (P-450scc, P-450(11 beta)). The structure of the gene is discussed in relation to present knowledge about the mechanism of regulation of the 25-hydroxyvitamin D3 24-hydroxylase and calcium homeostasis.

Amino Acid Sequence↗
PubMed1993

Flow cytometric detection of recombinant human granulocyte-colony stimulating factor binding to leukemic cells.

To examine binding of recombinant human granulocyte-colony stimulating factor to myeloid cells, the factor was labeled with fluorescein isothiocyanate, and incubated with blood specimens, which were then analyzed by flow cytometry. Neutrophils demonstrated an increased fluorescence, while lymphocytes were negative. These cell fractions were used as controls for cytometric binding assays of leukemic cells. Six patients with lymphocytic leukemia were negative in this assay. Ten of 15 patients with myelocytic leukemia were positive. All patients (n = 5) in myeloblastic crisis of chronic myelogenous leukemia were also positive. The flow cytometry results correlated well with the results of colony formation in response to granulocyte-colony stimulating factor. The results indicate that our method is useful in predicting the susceptibility of leukemic cells to recombinant growth factors.

Flow Cytometry↗
PubMed1993

Strong immunogenicity of a multicomponent peptide vaccine developed with the branched lysine oligopeptide method for human immunodeficiency virus infection.

We synthesized one V3 peptide each from HTLV-IIIB, Thai A and Thai B, conjugating them to the T cell epitope of the env region, and we also synthesized a p17 protein peptide of the gag region (HGP-30). These peptides were then coupled to 8-lysine copolymers using N-succinimidyl maleimido carboxylate (M(r) = ca 60,000). We designated this the branched lysine oligopeptide method. The large peptide complexes constructed from these four macromolecular peptides were used with aluminium hydroxide or complete Freund's adjuvant to immunize mice and rabbits four times. ELISA assay showed high titres of anti-peptide antibodies to each V3 loop peptide and the HGP-30 peptide. Strong inhibition of CD4+ dependent cell fusion was obtained with these antisera when IIIB, Thai A and Thai B strains of the human immunodeficiency virus (HIV) were used. Strong anti-fusion inhibition was also observed with two other HIV strains. In addition, an increase of the anti-HIV effect was observed when we used sera obtained by multicomponent vaccine immunization. The same kind of inhibition was also observed in p24 assay systems using these immunized antisera. Activation of IL-2 production in lymphocytes was observed in mice immunized with this vaccine. These results suggest that immunization with macromolecular peptide complexes can result in strong immunogenicity towards HIV-1.

AIDS Vaccines↗
PubMed1993

Intratumor ethanol injection.

In this discussion, the history of development of intratumor ethanol injection therapy for hepatocellular carcinoma, the principle, indications, technique, and our own experience in 125 patients are described. This therapy is perhaps preferred to other modalities for small, small-numbered cancers in patients with poor risk for resection.

Carcinoma, Hepatocellular↗
PubMed1993

Genetic variation in VP7 gene of human rotavirus serotype 1 (G1 type) isolated in Japan and China.

Sequence analysis of the gene encoding the major neutralization glycoprotein (VP7) was performed on 12 human isolates of serotype 1 of rotavirus in Japan and China. They were examined for genetic variations among serotype 1 isolates. Comparative studies of their nucleotide and deduced amino acid sequences between the 12 isolates and the Wa strain revealed an overall homology of more than 92 and 96%, respectively. Higher degrees of homologies were observed between Wa and 2 strains (K1 and K2) in Tokyo, 1979-1980, than between Wa and recent isolated strains in Tokyo and in China. In our isolates, a total of 16 amino acid residues frequently converted to another amino acid. Six amino acid residues belonging to the major neutralizing epitope regions (B, D, and E in this communication) frequently converted. From these data three subtypes (subtypes A, B, and intermediate) were suggested to be divided. Whether these differences are an important mechanism in the epidemiology of rotaviruses requires further investigation.

Amino Acid Sequence↗
PubMed1993

Oxidative metabolism in the myocardium in normal subjects during dobutamine infusion.

To assess the biventricular response of the clearance rate of carbon-11 acetate as an index of myocardial oxidative metabolism to increase in work-load, dynamic positron emission tomography was performed at rest and during dobutamine infusion in 14 normal subjects. The clearance rate constant (Kmono) of the left ventricular (LV) myocardium increased during dobutamine infusion (0.112 +/- 0.020 min-1 vs 0.065 +/- 0.015 min-1 at rest) (P < 0.001) in proportion to the increase in the pressure-rate product. Kmono in the right ventricular (RV) myocardium also increased (0.080 +/- 0.018 min-1 vs 0.034 +/- 0.013 min-1 at rest) (P < 0.001), with an excellent correlation with the LV Kmono (r = 0.920). The fact that the increase in RV Kmono during dobutamine infusion was greater (158% +/- 81%) than that in LV Kmono (79% +/- 39%) (P < 0.005) indicates a greater increase in oxidative metabolism in the RV in response to inotropic stimulation in normal subjects.

Acetates↗
PubMed1993

A model for feature linking via collective oscillations in the primary visual cortex.

A neural network model for explaining experimentally observed neuronal responses in cat primary visual cortex is proposed. In our model, the basic functional unit is an orientation column which is represented by a large homogeneous population of neurons modeled as integrate-and-fire type excitable elements. The orientation column exhibits spontaneous collective oscillations in activity in response to suitable visual stimuli. Such oscillations are caused by mutual synchronization among the neurons within the column. Numerical simulation for various stimulus patterns shows that as a result of activity correlations between different columns, the amplitude and the phase of the oscillation in each column depend strongly on the global feature of the stimulus pattern. These results satisfactorily account for experimental observations.

Animals↗