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Biomedical subjects

K Maeda

Publications and source records attributed to K Maeda.

At least 775 records · Page 43Linked to original sources
PubMed1994

Split tolerance between spleen and lymph node cells in severe combined immunodeficiency mice grafted with AKR fetal liver cells.

Severe combined immunodeficient (SCID) mice defective in stem cells for T and B cells appear to be an ideal host for construction of chimeric mice. When bone marrow cells are used as a source of stem cells, however, host SCID mice do not always show sufficient reconstitution. In this study, fetal liver cells from AKR embryos were transplanted into SCID mice without prior irradiation. This treatment induced full reconstitution of lymphopoiesis as evaluated by flow cytometry analysis and serum Ig production 2 months after transplantation. Thus, fetal liver cells seem to be a better source for reconstitution of SCID mice than bone marrow cells. Lymph node (LN) cells of these mice (FLT mice) had no proliferative or cytotoxic activities against either host-type (C.B-17) or donor-type (AKR) spleen cells. However, spleen cells from FLT mice exhibited marked proliferative and cytotoxic activities against C.B-17 cells, with no activities against AKR cells. Split tolerance against C.B-17 cells in spleen and LN cells was not a transient phenomenon, since similar results were obtained from a cytotoxic T lymphocyte assay 4 months later. In spite of the strong host reactivity in vitro, aberration of clonal deletion or development of a graft-versus-host disease was not seen in FLT mice. As IL-2 induced the host reactivity of LN cells in a mixed lymphocyte reaction, potentially host-reactive T cells were present in LN but were rendered anergic. Tolerance in FLT mice seems to be regulated by a peripheral mechanism. We supposed that the split tolerance in FLT mice was induced by the different antigenicity between the spleen and LN.

Animals↗
PubMed1994

Inhibition of feline immunodeficiency virus gene expression and replication by alphaherpesvirus ICP4 homologues.

We investigated the effects of pseudorabies virus (PRV), herpes simplex virus type 1 (HSV-1), and equine herpesvirus type 1 (EHV-1) ICP4 homologues on feline immunodeficiency virus (FIV) long terminal repeat (LTR)-directed gene expression. This was done by using the transient expression chloramphenicol acetyltransferase (CAT) assay in Crandell feline kidney (CRFK) and Felis catus whole fetus 4 cells transfected with a chimeric FIV LTR-CAT reporter construct in combination with effector plasmids expressing the PRV, HSV-1 or EHV-1 ICP4 homologue. The experiments demonstrated that the ICP4 homologues could significantly inhibit FIV LTR-directed gene expression. Moreover, the ICP4 homologues also exhibited a marked inhibitory effect on FIV replication in CRFK cells cotransfected with an infectious molecular clone of FIV.

Animals↗
PubMed1994

Possible involvement of the lysine epsilon-aminotransferase gene (lat) in the expression of the genes encoding ACV synthetase (pcbAB) and isopenicillin N synthase (pcbC) in Streptomyces clavuligerus.

Streptomyces clavuligerus produces the beta-lactam antibiotics penicillin N, O-carbamoyldeacetylcephalosporin C and cephamycin C. We characterized a wild-type DNA region which restores antibiotic formation to a mutant strain named NP1, previously shown to exhibit depressed activities for two early enzymes of cephalosporin synthesis, delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase (ACVS) and isopenicillin N synthase (IPNS). L-Lysine epsilon-aminotransferase (LAT) assays and alpha-AAA feeding experiments suggested that strain NP1 is a lat mutant. NP1 recovered LAT, ACVS and IPNS activities when transformed with the cloned region. DNA sequencing showed that this region encodes the entire LAT gene (lat), required for the conversion of L-lysine to the beta-lactam precursor L-alpha-aminoadipic acid (alpha-AAA), as well as the upstream half of the ACVS gene (pcbAB). The activities of ACVS and IPNS appear to depend upon LAT expression. Gene fusions constructed to investigate promoter activities in the cloned region support a model of interdependence in the expression of the genes for LAT, ACVS and IPNS (pcbC).

Amino Acid Sequence↗
PubMed1994

Close correlation of the cardioprotective effect of FK409, a spontaneous NO releaser, with an increase in plasma cyclic GMP level.

FK409 ((+/-)-(E)-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexeneamide) , which has been reported by us to be a new spontaneous nitric oxide (NO) releaser, prevented myocardial infarction following occlusion and reperfusion in rat coronary artery and increased plasma cyclic GMP level in rats, dose-dependently and significantly at 32 mg kg-1. Isosorbide dinitrate (ISDN), which is the most popular orally active NO donor used in the treatment of ischaemic cardiovascular diseases, did not show significant effects at 32 mg kg-1 in either experiment. Therefore, it is suggested that FK409 can attenuate myocardial injury during ischaemia and reperfusion in contrast to ISDN and a change in plasma cyclic GMP level may serve as an indicator of the cardioprotective effect of NO-releasing drugs.

Animals↗
PubMed1994

Antiplatelet activities of FK409, a new spontaneous NO releaser.

1. We reported that (+/-)-(E)-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexeneamide (FK409) released nitric oxide (NO) spontaneously with a chemiluminescence analyzer. The aim of this study was to compare antiplatelet activities of FK409, a new NO releaser, with those of isosorbide dinitrate (ISDN) in vivo and in vitro. In order to elucidate the differences in antiplatelet activities between FK409 and ISDN, we compared their modes of action. 2. In in vitro experiments, FK409 had a more potent inhibitory effect on rat platelet aggregation induced by adenosine 5'-diphosphate (2.0 microM) than ISDN (IC50 = 4.32 +/- 0.95 microM and > 100 microM respectively). 3. In the rat extracorporeal shunt model (in vivo experiments), FK409 suppressed thrombus formation dose-dependently from 0.32 mg kg-1, p.o. and showed the maximum inhibition (52% inhibition vs. vehicle treatment) at 10 mg kg-1, p.o., while ISDN showed no inhibition at 10 mg kg-1 and only 17% inhibition at 32 mg kg-1, p.o. 4. FK409 could generate nitrite, which is an oxidative product of NO, much faster than ISDN in phosphate buffer solution and rat plasma during 60-min incubation at 37 degrees C. 5. These data show that FK409 has more potent antiplatelet effects than ISDN, by acting through spontaneously released NO.

Animals↗
PubMed1994

Antianginal effects of FK409, a new spontaneous NO releaser.

1. The aim of this study was to compare antianginal effects of (+/-)-(E)-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexeneamide (FK409), a new spontaneous nitric oxide releaser, with those of isosorbide dinitrate (ISDN). We used two types of rat angina model; methacholine- and arginine vasopressin (AVP)-induced coronary vasospasm models. 2. In the in vitro study, FK409 showed 80 times more potent vasorelaxant effect in dog isolated coronary artery than ISDN (EC50 = 16.7 +/- 4.8 and 1340 +/- 320 nM, respectively). 3. In the rat methacholine-induced coronary vasospasm model, FK409 suppressed the elevation of ST segment dose-dependently and significantly at 0.1 mg kg-1, i.d. On the other hand, ISDN suppressed it significantly at 3.2 mg kg-1, i.d. In addition, the efficacy of 3.2 mg kg-1 ISDN in the model was almost the same as that of 0.1 mg kg-1 FK409. 4. In the above experiments, FK409 and ISDN decreased mean blood pressure significantly at the maximum dose tested (1.0 mg kg-1, i.d. and 3.2 mg kg-1, i.d., respectively) but did not change heart rate at these doses. Therefore, the hypotensive effect of FK409 was 10 times weaker than the antianginal effect of the compound, while those of ISDN were almost the same. 5. In the rat AVP-induced coronary vasospasm model, 32 mg kg-1 FK409 significantly inhibited the depression of ST segment 60 min after oral administration. On the other hand, 32 mg kg-1 ISDN did not inhibit it at 60 and 120 min after oral administration. 6. In conclusion, FK409 inhibits coronary vasospasm more potently in two types of rat angina models than ISDN. In addition, FK409 shows an antianginal effect more selectively that a hypotensive effect,compared with ISDN.

Angina Pectoris, Variant↗
PubMed1994

Expression of membrane alkaline phosphatase activity on gingival fibroblasts in chronic inflammatory periodontal disease.

We investigated the expression of membrane alkaline phosphatase (ALP) activity on fibroblasts in inflamed gingiva from 7 patients with adult periodontitis. ALP activity was ultrahistochemically detected by a cerium-based capture method. The degree of ALP activity was estimated by morphometric analysis of the percentage of the perimeter on which ALP reaction product was deposited. Fibroblasts in the non-inflammatory connective tissue were surrounded by bundles of collagen fibrils, and the majority of these fibroblasts showed ALP-negative or weakly ALP-positive reaction. By contrast, fibroblasts in the inflammatory connective tissue were either surrounded by a non-collagenous substance or in contact with inflammatory cells, and the majority of these fibroblasts showed a strong ALP-positive reaction. These results suggest that the expression of membrane ALP activity on gingival fibroblasts is induced by microenvironmental changes associated with the loss of contact between the cells and the extracellular collagenous matrix during inflammatory reactions.

Adult↗
PubMed1994

Immunohistochemical examination on the localization of macrophages and plasma cells in induced rat periapical lesions.

To investigate the role of plasma cells and macrophages in the development of periapical lesions, we immunohistochemically examined the distribution of these inflammatory cells in experimental induced rat periapical lesions after pulpectomy. The number of ED1-positive mononuclear cells increased rapidly, reached a plateau which remained stable between days 10 and 60, and subsequently decreased. Immunoglobulin (Ig)-bearing plasma cells appeared after 60 days, and, of these, IgG-bearing plasma cells were predominant after 90 days. The radiographic and histopathological findings indicated the development of bone destruction at 10 days which continued until 60 days; tissue repair began to take place after 90 days. The results suggested that macrophages had a close relation to bone destruction and that plasma cells might participate in tissue repair rather than the development of periapical lesions.

Alveolar Bone Loss↗
PubMed1994

[Suppression of the Pseudomonas aeruginosa-induced biofilm formation on human epithelial cells by erythromycin].

In the present study, were examined the inhibitory effect of erythromycin on the biofilm formation by a temperature-sensitive mutant (Ts25) of Pseudomonas aeruginosa N-42 on the surface of Ishikawa cells which can produce a mucin-like glycoprotein physicochemically similar to mucoproteins produced in the human airway. Usually, 38-45 microcolonies (biofilms) were formed after 10 days of incubation in cultures of Ishikawa cells and P. aeruginosa Ts25. Erythromcin suppressed the adhesion to Ishikawsa cells of P. aeruginosa and its subsequent biofilm formation at doses as low as 0.2 microgram/ml. Erythromycin also exhibited the suppressive effect on the production of glycoproteins by Ishikawa cells at doses higher than 1 microgram/ml and the production of elastase and exoenxyme A from P. aeruginosa at doses higher than 2 micrograms/ml. These results suggest that erythromycin can inhibit the biofilm formation in culture of human epithelial cells and P. aeruginosa and the in-vivo bacterial biofilm formation may be attributed to host cell-derived factors rather than bacterial products.

Biofilms↗
PubMed1994

[An evaluation of pathogens in patients with bronchopulmonary infection by transtracheal aspiration: December 1978-March 1993].

We performed transtracheal aspiration (TTA) in 1165 patients, who were suspected to have bronchopulmonary infection, from December 1978 to March 1993. We isolated pathogens from TTA in 806 patients (69.2%). We isolated H. influenzae (62 cases), S. pneumoniae (39 cases) and M. catarrhalis (24 cases) in patients with acute bronchitis, S. pneumoniae (65 cases), alpha-Streptococcus sp. (52 cases), H. influenzae (32 cases) and S. aureus (29 cases) in patients with pneumonia or lung abscess and H. influenzae (174 cases), S. pneumoniae (84 cases), P. aeruginosa (81 cases) and M. catarrhalis (42 cases) in patients with chronic lower respiratory tract infection. Anaerobic bacteria isolated from TTA included Peptostreptococcus sp. (19 cases), Bacteroides sp. (19 cases) and others. Mycoplasma pneumoniae was isolated from TTA in 8 patients with pneumonia without other organisms. Virus isolated from TTA included Rhinovirus (6 cases) and others. These results suggest that various pathogens affect the pathogenesis of bronchopulmonary infection. Therefore, we must diagnose the bronchopulmonary infection by the correct methods such as TTA.

Adult↗
PubMed1994

[A clinical study of respiratory infections due to mucoid Pseudomonas aeruginosa diagnosed by transtracheal aspiration].

We performed a clinical study of 20 cases (33 episodes) of respiratory infections due to mucoid Pseudomonas aeruginosa by transtracheal aspiration (TTA) in the recent 10 years. There was only one pneumonia without underlying chronic lower respiratory infection (CLRTI) case positive for mucoid P. aeruginosa and others were all CLRTI among 33 TTA trials. In contrast, nonmucoid P. aeruginosa was recovered from 9 cases of respiratory infections without underlying CLRTI among 46 TTA trials. Monomicrobial infection of mucoid P. aeruginosa was 69.7%, and polymicrobial infection containing mucoid P. aeruginosa was 30.3%, and Haemophilus influenzae was the most frequent microorganism recovered with mucoid P. aeruginosa. The recovery rate of mucoid P. aeruginosa among P. aeruginosa-colonized cases was 56.3% in diffuse panbronchiolitis, and that was 42.9% and 40.0% in bronchiectasis and chronic bronchitis, respectively. Mortality due to pneumonia with nonmucoid P. aeruginosa was 46.1%, but there was no fatal pneumonia case with mucoid P. aeruginosa. In CLRTI, laboratory data were not remarkably different between mucoid and non-mocoid P. aeruginosa-colonized cases. Thus, these results suggest that mucoid P. aeruginosa is a more important organism in persistent infections in the lower respiratory tract compared with nonmucoid P. aeruginosa, and further investigations is required on the mechanism and clinical role of this infection.

Adult↗
PubMed1994

[The role of viral infection in adults with bronchopulmonary infections].

We isolated the virus from the respiratory specimens of 16 patients (7.9%) when we investigated the bronchopulmonary infections of 203 adult patients by the viral isolation method for the diagnosis of the viral infection and transtracheal aspiration (TTA) for taking directly the specimen from the lower respiratory tract. The bronchopulmonary infections, isolated the virus, consisted of acute bronchitis (3 cases), pneumonia (8 cases) and the acute exacerbation of chronic lower respiratory infection (5 cases). The positive viral isolation consisted of Rhinovirus (11 strains), Herpes simplex virus I (3 strains), Parainfluenza virus III (1 strain) and Respiratory syncytial virus (1 stain). There were 9 transtracheal aspirates, 8 pharyngeal swabs and 5 nasal washings in the positive viral specimens. We experienced 5 cases who had the same virus isolated from both the upper respiratory tract and the lower respiratory tract. H. influenzae, P. aeruginosa and other bacteria were found in 14 of the 16 TTA cultures. These results suggest that the role of the viral infection is important either independently or relating the bacterial infection in the adult bronchopulmonary infections.

Adult↗
PubMed1994

[A clinical study of Pseudomonas pneumonia diagnosed by transtracheal aspiration].

We performed a clinical study of 16 cases (18 episodes) of Pseudomonas pneumonia by transtracheal aspiration (TTA) from April 1983 to March 1993. The isolation rate of Pseudomonas aeruginosa (P. aeruginosa) among 235 episodes of pneumonias with positive microorganism by TTA was 7.7%. All patients had one or more underlying disease. The most frequent underlying disease was chronic lower respiratory tract infection, followed by lung epidermoid cell carcinoma. More than half of the cases had been given antibiotics prior to the occurrence of pneumonia, and administration of adrenal corticosteroid, heavy smoking habit, and aspiration were seen as other predisposing factors concerning the onset of pneumonias. Monomicrobial infection of P. aeruginosa was 61.1%, and polymicrobial infection containing P. aeruginosa was 38.9%. Community-acquired pneumonia was 61.1% and hospital-acquired pneumonia was 38.9%; the rates of polymicrobial infections and prior administration of antibiotics were higher in the latter group. Mortality due to Pseudomonas pneumonia was 27.8% and the levels of serum albumin and total protein at the onset of pneumonia were significantly lower in the fatal cases than in the recovered cases. It was considered that not only general underlying disease which weaken the immunological resistance of the host, but local bronchial lesion was also important to the onset of the Pseudomonas pneumonia. Also, nutrition is an important prognostic factor on the host's side.

Adult↗
PubMed1994

[Determination of neutrophil function in respiratory infection by chemiluminescence (CL). II: Changes in neutrophil's CL by chemotherapy against chronic lower tract infection].

Neutrophil's CL (CL-index) in were assayed in 18 patients with chronic lower tract infection (13 cases in the exacerbated phase and five cases in the stable phase) three times per case: before, during and after chemotherapy. Before the initiation of chemotherapy, the CL-index.N (neutrophil numbers x CL-index) in patients with exacerbation remained higher than in those without exacerbation. At the exacerbated phase, the CL-index of nine patients and the CL-index.N of 10 patients fell lower than those obtained before treatment. AT the stable phase, the CL-index and the CL-index.N did not change remarkably during and after chemotherapy.

Adult↗
PubMed1994

[Clinical study of pneumonia in elderly patients using transtracheal aspiration (TTA)].

A clinical study was conducted to clarify the clinical state of pneumonia in elderly patients using transtracheal aspiration (TTA). Without prior administration of antibiotics, S. pneumoniae was the most clinically significant in both elderly and non-elderly groups whether the onset of pneumonia was hospital acquired pneumonia or community acquired pneumonia. Compared to the non-elderly group, multiple pathogens were isolated more frequently in the elderly group. Analysis about host factors showed that the number of underlying diseases per patient was more along those with poorer general conditions in the elderly group. The Brinkmann Index was also significantly higher in the elderly group. Clinical examinations before onset of pneumonia indicated that serum total protein, albumin and DNCB skin reaction were significantly lowered in the elderly group. Over the clinical course, the prognosis was poorer and the incidence of adverse reactions of antibiotics tended to be more in the elderly group. These results suggest that a complex clinical background exists for pneumonia of elderly people, related to poorer prognosis. Therefore, more cautious and meticulous care should be provided to elderly patients with pneumonia.

Adolescent↗
PubMed1994

Structural modification of cell wall mannans of Candida albicans serotype A strains grown in yeast extract-Sabouraud liquid medium under acidic conditions.

The cell wall mannans of two Candida albicans serotype A strains, NIH A-207 and J-1012 (abbreviated as A and J strains, respectively), cultured in yeast extract-Sabouraud liquid medium at pH 2.0, contained neither a phosphate group nor a beta-1,2-linked mannopyranose unit (H. Kobayashi, P. Giummelly, S. Takahashi, M. Ishida, J. Sato, M. Takaku, Y. Nishidate, N. Shibata, Y. Okawa, and S. Suzuki, Biochem. Biophys. Res. Commun. 175:1003-1009, 1991). In this study, the mannans obtained from A and J strains grown in pH 2.0 medium (abbreviated as mannans A2 and J2, respectively) exhibited quite different reactivities against rabbit anti-C. albicans and anti-Saccharomyces cerevisiae sera compared with those of mannans from the corresponding strains cultured in conventional medium at pH 5.9 (abbreviated as mannans A and J, respectively). Namely, mannans A2 and J2 lost reactivity against the former serum but reacted with the latter serum to a higher extent than mannans A and J. In order to account for these difference in more detail, mannans A2 and J2 were subjected to acetolysis. Elution profiles of the acetolysates were completely different from those of acetolysates obtained from mannans A and J reported in our previous papers. The 1H nuclear magnetic resonance spectra of the oligosaccharides from mannans A2 and J2 obtained by this procedure indicate that the side chains are composed of alpha-linked mannopyranose units densely linked to the alpha-1,6-linked backbone. The long side chains containing one alpha-1,3-linked mannopyranose unit are markedly increased.

Candida albicans↗