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Biomedical subjects

T Koga

Publications and source records attributed to T Koga.

At least 73 records · Page 4Linked to original sources
PubMed2001

Influence of dentition status on physical disability, mental impairment, and mortality in institutionalized elderly people.

The loss of teeth is known to influence the mastication of foods and nutritional status. Therefore, we hypothesize that poor dentition status can impair the systemic health of the aged. To clarify the influence of dentition status on deterioration in physical ability, mental impairment, and mortality, we conducted a six-year prospective cohort study of the institutionalized elderly living in 29 of the 30 institutions for the elderly in Kitakyushu, Japan. Bivariate analysis revealed that worse dentition status at baseline led to significantly worse physical and mental impairment, and higher mortality. In a multiple logistic regression analysis, the physical ability of edentulous subjects without dentures significantly deteriorated compared with that of dentate subjects with 20 or more teeth. The six-year mortality rate of the edentulous subjects without dentures was significantly higher than that of the subjects with 20 or more teeth. Poorer dentition status, especially edentulousness without dentures, may therefore be related to deterioration in the systemic health of the aged.

Aged↗
PubMed2001

Immunodominant region of Actinobacillus actinomycetemcomitans 40-kilodalton heat shock protein in patients with rheumatoid arthritis.

Bacterial heat shock proteins have been implicated in the pathogenesis of several diseases, and the immunological relationship between rheumatoid arthritis (RA) and Escherichia coli DnaJ has been reported. Since there are similarities in the tissue destruction process of RA and periodontitis, we examined the reactivities of antibodies in sera from RA patients to the DnaJ protein from Actinobacillus actinomycetemcomitans. An enzyme-linked immunosorbent assay showed that IgG titers to the N-terminal conservative region of the DnaJ are significantly higher in RA patients compared with the healthy controls (p < 0.05). Furthermore, we examined IgG titers of disease controls to determine the specificity of the immune responses to this region in RA patients. The difference between RA and infectious disease patients was also significant (p < 0.05). These results suggest that the N-terminal region of DnaJ from A. actinomycetemcomitans may contribute to the etiologic analysis of RA.

Adult↗
PubMed2001

Relationship between upper body obesity and periodontitis.

Upper body obesity, related to visceral fat accumulation, is known to increase the risk of various adult diseases, especially type 2 diabetes and cardiovascular disease. This study was conducted to clarify the relationship between upper body obesity and periodontitis. We studied 643 apparently healthy, dentulous Japanese adults who attended programs at Fukuoka Health Promotion Center. Waist-hip ratio, body-mass index (BMI), and body fat were significant risk indicators for periodontitis after adjustment for known risk factors (p < 0.002). Subjects were divided into four BMI (or body fat) categories. In only the subjects with high waist-hip ratio, higher categories of BMI (or body fat) significantly increased the adjusted risk of periodontitis, compared with subjects with low waist-hip ratios and the lowest category of BMI (or body fat). The reported relationship between cardiovascular disease and periodontitis should be reconsidered, since abdominal adiposity or visceral fat can be related to both diseases.

Abdomen↗
PubMed2001

Oral health condition and endemic goitre, in an iodine-deficient area in Bali, Indonesia.

Iodine deficiency is a major determinant of endemic goiter which affects bone growth. The purpose of this study was to clarify the relationship between iodine deficiency and oral health. A cross-sectional survey was carried out on 181 inhabitants aged 17 to 40 years in two villages in an iodine-deficient area in Bali, Indonesia. Thyroid swelling, serum level of thyroid-stimulating hormone, DMFT index, plaque index, gingival index, dietary habits and socioeconomic status were examined. Thirty two subjects (21%) had thyroid swelling considered to be endemic goiter, with the highest prevalence in females aged 21 to 30 years (40-41%). The DMFT, food habits, and socioeconomic status were different between both villages. Multiple regression analysis adjusted for age, sex, and location (village) did not detect any association between DMFT and serum thyroid-stimulating hormone level or thyroid swelling. Further studies will be required to confirm these findings.

Adolescent↗
PubMed2001

Clinicopathological and molecular evidence indicating the independence of bronchioloalveolar components from other subtypes of human peripheral lung adenocarcinoma.

Although human lung adenocarcinoma has diverse histological subtypes, the correlation between histological subtypes and occurrence of the p53 gene mutation has been given less attention. We investigated 145 surgically resected lung adenocarcinomas to search for the incidence of p53 mutations and for record data on survival in each histological subtype, according to the new WHO criteria (1999). The frequency of p53 mutation in bronchioloalveolar carcinoma (BAC; 0% in 17 cases) and BAC with invasive growth component (BAC-invasive; 11% in 27 cases), which is conventionally categorized as the mixed subtype in WHO typing, were apparently significantly lower than in other types (non-BAC including acinar, papillary, solid, or mixed histology with these subtypes; 48% in 101 cases; P < 0.01). Multivariate analysis revealed that the histological subtype including BAC-invasive was a strong, independent, and significant prognostic factor (P < 0.03), as were tumor size and pathological stage (P < 0.001 and 0.002, respectively) for overall survival. However, the occurrence of p53 mutation itself was seen to be significant only in case of the univariate analysis. Therefore, histological subtyping may be a better prognostic indicator than is p53 mutation. These findings suggest that the WHO classification with the BAC and BAC-invasive from other histological subtypes may prove useful to predict the outcome for surgically treated patients with lung adenocarcinoma.

Adenocarcinoma↗
PubMed2001

[Inhaled nitric oxide therapy].

Inhaled nitric oxide (INO) therapy is becoming an indispensable measure in some critically ill patients with pulmonary hypertension. Most importantly, it has been shown that INO significantly reduces the necessity for extracorporeal lung assist in newborns with hypoxemic respiratory failure and pulmonary hypertension. A large number of basic and clinical studies are making great steps in delineating its physiology, techniques, side effects, and clinical efficacy. This article reviews the current knowledge of INO therapy including a novel device of nitric oxide production system.

Administration, Inhalation↗
PubMed2001

[Evaluation of dermatological symptoms of Yusho patients in the annual examination in 1999-2000].

We analyzed the severity grades of the skin symptoms of Yusho patients who visited the annual examinations in 1999 and 2000. The severity grades of the skin symptoms clearly improved. The patients graded as 0 increased and those graded as II.III-III or III.IV-IV decreased as compared to the data in 1993. The pattern of the skin severity scores did not change much, although the patients who showed 0.1 reached 68% in 2000. The blood PCB concentration of Yusho patients also clearly decreased, especially in the patients who showed "A" pattern. Furthermore, the skin changes of the aged patients should be analyzed in detail in the future.

Female↗
PubMed2001

Treatment of ulcerative endobronchial tuberculosis and bronchial stenosis with aerosolized streptomycin and steroids.

OBJECTIVES: Endobronchial tuberculosis (EBTB) is defined as a tuberculous infection of the tracheobronchial tree. It has been reported that aerosolized therapy with streptomycin and steroids is useful for EBTB; however, the effectiveness of this therapy for bronchial stenosis has yet to be clarified. This study was undertaken to determine the effectiveness of aerosol therapy in the treatment of bronchial stenosis due to EBTB. DESIGN: An observational, historical, controlled comparative study. Retrospective analysis of 27 patients treated with conventional therapy, and prospective analysis of 30 patients treated with aerosol therapy. METHOD AND PATIENTS: Flexible bronchoscopy was performed at least twice in 57 patients with ulcerative EBTB, in whom the degree of bronchial stenosis between the first and last bronchoscopic examinations was estimated. Bronchial stenosis was graded as minimal, mild, moderate, severe or obstructive, and the follow-up of bronchial stenosis assessed as aggravation, no change or improvement. RESULTS: Conventional therapies led to aggravation in 13 patients, no change in 13 patients, and improvement in one patient. Aerosol therapy led to no change in 27 patients, and improvement in three patients. No patients developed aggravation. The differences between the therapeutic groups were significant. CONCLUSION: Aerosol therapy helps to prevent progressively severe bronchial stenosis due to EBTB.

Administration, Inhalation↗
PubMed2001

The antithrombotic efficacy of AT-1459, a novel, direct thrombin inhibitor, in rat models of venous and arterial thrombosis.

The antithrombotic efficacy of AT-1459, a novel, direct thrombin inhibitor (Ki = 4.9 nM) was evaluated in rat models of venous thrombosis combined with a bleeding time test and arterial thrombosis. After drugs were given by i. v. bolus injection plus a continuous infusion, the ID50, (a dose that exhibits 50% inhibition of thrombus formation over each vehicle group) values of AT-1459, argatroban, and dalteparin were 0.04 mg/kg plus 0.04 mg/kg/h, 0.1 mg/kg plus 0.4 mg/ kg/h, and 13.0 IU/kg plus 26.0 IU/kg/h, respectively, in the venous thrombosis study. The BT2 (a dose that causes 2-fold prolongation of bleeding time over each vehicle group) values of AT-1459, argatroban, and dalteparin were 0.9 mg/kg plus 0.9 mg/kg/h, 1.0 mg/kg plus 0.6 mg/kg/h, and 345.5 IU/kg plus 691.0 IU/kg/h in the rat tail transection model. The ratios of BT2/ID50 of AT-1459, argatroban, and dalteparin were 22.5, 10.0, and 26.6, respectively. In a rat model of arterial thrombosis induced by topical FeCl2 application, intravenous administration of AT-1459, argatroban, and dalteparin improved the vessel patency significantly (P < 0.01) at 0.6 mg/kg plus 0.6 mg/kg/h, 0.6 mg/kg plus 2.4 mg/kg/h, and 300 IU/kg plus 600 IU/kg/h, respectively. The oral antithrombotic effect of AT-1459 lasted for 6 after administering 30 mg/kg and improved the vessel patency significantly 1 h after administering the same dose in venous and arterial thrombosis models, respectively, with a rapid onset of action. Warfarin also inhibited thrombus weight and improved the vessel patency significantly after oral administration of 0.3 mg/kg for three consecutive days in the same study. The antithrombotic and hemorrhagic effects of all drugs studied were correlated with plasma concentration or clotting times. These results suggest that AT-1459 may be clinically useful as an orally available antithrombotic agent for the prevention of venous and arterial thrombosis.

Administration, Oral↗
PubMed2000

Genetic analysis of the gene cluster for the synthesis of serotype a-specific polysaccharide antigen in Aactinobacillus actinomycetemcomitans.

The serotype a-specific polysaccharide antigen (SPA) of Actinobacillus actinomycetemcomitans consists of 6-deoxy-D-talose. A gene cluster associated with the biosynthesis of SPA was cloned and sequenced from the chromosomal DNA of A. actinomycetemcomitans SUNYaB 75 (serotype a). This cluster consisted of 14 open reading frames. Insertional inactivation of eight genes in this cluster resulted in loss of the ability of A. actinomycetemcomitans SUNYaB 75 cells to produce the polysaccharide. A protein database search revealed that the 11 sequential genes containing these eight genes were not found in SPA-associated gene clusters of the other serotypes of A. actinomycetemcomitans. These results suggest that the gene cluster is unique to serotype a and is essential to the synthesis of the SPA.

Aggregatibacter actinomycetemcomitans↗
PubMed2000

Evidence for early aging in the mucosal immune system.

Despite recent advances in the cellular and molecular analysis of induction and regulation of mucosal immune responses, little is yet known about differences which occur in aging. To address this important issue, we have compared the mucosal and systemic immune responses of aged (12- to 14-mo- or 2-year-old) and young adult (6- to 8-wk-old) C57BL/6 mice. Both aged and young mice were immunized weekly with three oral doses of 1 mg of OVA and 10 microg of cholera toxin (CT) as mucosal adjuvant. Both groups of mice over 1 or 2 years of age showed reduced levels of Ag-specific mucosal or systemic immune responses at day 21. An Ag-specific B cell enzyme-linked immunospot assay confirmed these results at the cellular level. When the Ag-induced cytokine responses were examined at both protein and mRNA levels, CD4(+) T cells from spleen and Peyer's patches of young adult mice revealed elevated levels of IL-4 production; however, these cytokine responses were significantly diminished in aged mice. In contrast to mucosal immunization, mice s. c. immunized with OVA plus CT resulted in impaired OVA-specific but intact CT B subunit-specific immune responses in 12- to 14-mo-old mice although the responses to both Ags were depressed in 2-year-old mice. These results provide the first evidence that the development of age-associated alterations possibly occurs earlier in the mucosal immune system than in the systemic immune compartment.

Adjuvants, Immunologic↗
PubMed2000

In vitro and in vivo studies of AT-1362, a newly synthesized and orally active inhibitor of thrombin.

AT-1362 was found to be a potent, selective, and competitive inhibitor of thrombin, with a Ki value of 6.7 nM. In a rat model of venous thrombosis induced by partial stasis and endothelial disruption, the ID(50) values (a dose required to obtain 50% inhibition of thrombus formation over each vehicle group) of AT-1362 and argatroban were 0.03 mg/kg i.v. plus 0.5 microg/kg/minute and 0. 13 mg/kg i.v. plus 8.7 microg/kg/minute, respectively, and the antithrombotic effect of AT-1362 without prolongation of bleeding time lasted for 2 hours and disappeared 4 hours after oral administration of 30 mg/kg. In the rat tail transection model, the BT(2) values (a dose causing two-fold prolongation of the bleeding time over each vehicle group) of AT-1362 and argatroban were 0.56 mg/kg i.v. plus 9.3 microg/kg/minute and 1.1 mg/kg i.v. plus 73.3 microg/kg/minute, respectively. The reduction of thrombus formation and the prolongation of bleeding time were correlated with an ex vivo activated partial thromboplastin time (APTT) for both drugs. AT-1362 at 0.3 mg/kg i.v. plus 5 microg/kg/minute and argatroban at 0.6 mg/kg i.v. plus 40 microg/kg/minute significantly (p<0.05 and p<0.01, respectively) improved the vessel patency in a FeCl(2)-induced carotid artery thrombosis model in rats. These results suggest that AT-1362 may be a potent antithrombotic agent for the treatment of thrombotic diseases.

Administration, Oral↗
PubMed2000

A gene cluster for the synthesis of serotype d-specific polysaccharide antigen in Actinobacillus actinomycetemcomitans.

The serotype d antigen of Actinobacillus actinomycetemcomitans consists of D-glucose, D-mannose, and L-rhamnose in a molar ratio of 1:2:1. A gene cluster involved in the synthesis of serotype-specific polysaccharide antigen was cloned from the chromosomal DNA of A. actinomycetemcomitans IDH 781 (serotype d). This cluster consisted of 12 open reading frames. Insertional inactivation of six genes in this cluster resulted in loss of ability of A. actinomycetemcomitans IDH 781 cells to produce the polysaccharide. Comparing the structure of the gene cluster with similar clusters from other serotypes of A. actinomycetemcomitans, showed that eight genes are unique to serotype d; the other four genes are involved in the biosynthesis of dTDP-L-rhamnose. These results suggest that the synthesis and structure of serotype d-specific polysaccharide of A. actinomycetemcomitans is quite different from those of other serotype strains.

Actinobacillus↗
PubMed2000

Expression profiling reveals distinct sets of genes altered during induction and regression of cardiac hypertrophy.

Although cardiac hypertrophy has been the subject of intensive investigation, regression of hypertrophy has been significantly less studied, precluding large-scale analysis of the relationship between these processes. In the present study, using pharmacological models of cardiac hypertrophy in mice, expression profiling was performed with fragments of more than 4,000 genes to characterize and contrast expression changes during induction and regression of hypertrophy. Administration of angiotensin II and isoproterenol by osmotic minipump produced increases in heart weight (15 and 45%, respectively) that returned to preinduction size after drug withdrawal. From multiple expression analyses of left ventricular RNA isolated at daily time-points during cardiac hypertrophy and regression, we identified sets of genes whose expression was altered at specific stages of this process. While confirming the participation of 25 genes or pathways previously shown to be altered by hypertrophy, a larger set of 30 genes was identified whose expression had not previously been associated with cardiac hypertrophy or regression. Of the 55 genes that showed reproducible changes during the time course of induction and regression, 32 genes were altered only during induction, and 8 were altered only during regression. This study identified both known and novel genes whose expression is affected at different stages of cardiac hypertrophy and regression and demonstrates that cardiac remodeling during regression utilizes a set of genes that are distinct from those used during induction of hypertrophy.

Angiotensin II↗
PubMed2000

Underground mating in the fiddler crab Uca tetragonon: the association between female life history traits and male mating tactics.

Brood size and other life-history traits of females affect male investment in mating. Female Uca tetragonon, producing relatively small broods, were attracted to the burrows of males for underground mating (UM) while carrying eggs. Most UM females released larvae and ovulated new broods during the pairing, averaging 3.9 days. While a female was incubating one brood, another brood was developing within the ovaries because the females were feeding adequately during incubation. These findings suggest that in U. tetragonon, a small-brood species, females increase the total number of broods produced by breeding continually. In contrast, in large-brood species, feeding by ovigerous females is relatively brief and not enough to prepare the next brood during incubation, inducing temporal separation between incubation and brood production. Unlike females in other ocypodids where females with large broods remain in the breeding burrows of males, most female U. tetragonon left the male after UM. Wandering in female U. tetragonon after the pairs separate may occur because their small broods are adequately protected by an abdominal flap. Relative brood size probably determines the vulnerability of the incubated broods to the females' surface behavior. Hence, male reproductive success in large-brood species may decrease greatly if males expel their mates after ovulation, although this is not necessarily so in small-brood species. Whether the male drives away the female or not may depend on which behavior within either small- or large-brood species yields the greater male reproductive success. In U. tetragonon some females extruded eggs in their own burrows after surface mating as well as in males' burrows after UM. It was unclear whether females chose a male with a larger burrow as an UM mate unlike several large-brood species. Burrows of both UM males and ovigerous females in U. tetragonon were relatively smaller than those in some large-brood species, indicating that incubation of small broods does not require large burrows. Rather than benefits of UM by female choice, wandering resulting from intersexual conflict, and sperm competition may explain why some females mate in males' burrows in this small-brood species.

Journal Article↗
PubMed2000

Thymidine diphosphate-6-deoxy-L-lyxo-4-hexulose reductase synthesizing dTDP-6-deoxy-L-talose from Actinobacillus actinomycetemcomitans.

The serotype c-specific polysaccharide antigen of Actinobacillus actinomycetemcomitans NCTC 9710 contains an unusual sugar, 6-deoxy-L-talose, which has been identified as a constituent of cell wall components in some bacteria. Two genes coding for thymidine diphosphate (dTDP)-6-deoxy-L-lyxo-4-hexulose reductases were identified in the gene cluster required for biosynthesis of serotype c-specific polysaccharide. Both dTDP-6-deoxy-L-lyxo-4-hexulose reductases were overproduced and purified from Escherichia coli transformed with the plasmids containing these genes. The sugar nucleotides converted by both reductases were purified by reversed-phase high performance liquid chromatography and identified by (1)H nuclear magnetic resonance and gas-liquid chromatography. The results indicated that one of two reductases produced dTDP-6-deoxy-L-talose and the other produced dTDP-L-rhamnose (dTDP-6-deoxy-L-mannose). The amino acid sequence of the dTDP-6-deoxy-L-lyxo-4-hexulose reductase forming dTDP-6-deoxy-L-talose shared only weak homology with that forming dTDP-L-rhamnose, despite the fact that these two enzymes catalyze the reduction of the same substrate and the products are determined by the stereospecificity of the reductase activity. Neither the gene for dTDP-6-deoxy-L-talose biosynthesis nor its corresponding protein product has been found in other bacteria; this biosynthetic pathway is identified here for the first time.

Aggregatibacter actinomycetemcomitans↗
PubMed2000

Mucosal vaccination and immune responses in the elderly.

To develop a mucosal vaccine strategy for the elderly, we have compared mucosal and systemic immune responses between aged (12-14 months) and young adult (8-12 weeks) mice. Both aged and young mice were immunized weekly with three oral doses of 1 mg of ovalbumin (OVA) and 10 microg of cholera toxin as adjuvant. Although elevated levels of OVA-specific systemic IgG and mucosal IgA Ab responses were seen in young mice, aged mice showed impaired antigen-specific mucosal and systemic immune responses. These results suggest that mucosal immunity is down regulated in aged mice.

Adjuvants, Immunologic↗