Biomedical subjects

K Yokota

Publications and source records attributed to K Yokota.

At least 73 records · Page 4Linked to original sources

PubMed2000

Combined effect of rebamipide and ecabet sodium on Helicobacter pylori adhesion to gastric epithelial cells.

Helicobacter pylori is a major etiological agent in gastroduodenal disorders. The adhesion of H. pylori to gastric epithelial cells is the initial step of H. pylori infection. Inhibition of H. pylori adhesion is thus a therapeutic target in the prevention of H. pylori infection. We have reported that rebamipide and ecabet sodium, mucoprotective antiulcer agents, independently inhibit H. pylori adhesion. However, the antiadhesion activity of each antiulcer agent was incomplete. Experiments were performed to evaluate the combined effect of rebamipide and ecabet sodium on H. pylori adhesion to gastric epithelial cells. MKN-28 and MKN-45 cells, derived from human gastric carcinomas, were used as target cells. Twelve clinical isolates of H. pylori were used in this study. We evaluated the effects of rebamipide and ecabet sodium, individually and in combination, on H. pylori adhesion to target cells quantitatively using our previously established enzyme-linked immunosorbent assay. Rebamipide and ecabet sodium each partially inhibited H. pylori adhesion. In contrast, adhesion was almost completely inhibited by pretreating target cells and H. pylori with the combination of rebamipide and ecabet sodium. Our studies suggest that the synergistic antiadhesion activity of rebamipide and ecabet sodium is greater than that of each antiulcer agent alone.

Abietanes↗

PubMed2000

[The bacteriocidal effect of the electrolysed functioning water against Helicobacter pylori].

The bacteriocidal effect of electrolysed functioning water against Helicobacter pylori was examined by both the culture method (viable count on agar plate) and the bacterial ATP content analysis (biolumminescence assay). The culture method revealed the water's reduced bacteriocidal effect on organic substances such as horse serum and bovine serum albumin. The bacterial ATP content determined by the treatment with lysis solution correlated with the bacterial cell count. The ATP of bacteria treated with electrolysed functioning water, benzalkonium chloride, and chlorhexidine gluconate was still present after contact with these solutions for 30 minutes, while the bacterial growth was completely inhibited by the culture method. Therefore, it was suggested that the bacterial ATP was derived from the coccoid form which was observed morphologically due to the action of these solutions. These results demonstrate that these solutions are not effective bacteriocidally against the coccoid form. Consequently, when we utilize functioning water in the field, we should keep in mind its nonbacteriocidal effect against the coccoid form, as well as its reduced effect under the condition of the contamination by organic substances.

Adenosine Triphosphate↗

PubMed2000

Antibody to heat shock protein can be used for early serological monitoring of Helicobacter pylori eradication treatment.

Infection with Helicobacter pylori induces humoral immune responses against various antigens of the bacterium. Heat shock proteins (hsps) are immunodominant antigens in various diseases including H. pylori infection. In the present study, we measured the anti-hsp antibody titers in 42 patients with H. pylori-infected peptic ulcers during a bacterial eradication study. The patients were treated with a proton pump inhibitor and antimicrobial agents to eradicate the organism. Their sera were obtained at pretreatment and at 1 month and 6 months after the eradication therapy. The titers of immunoglobulin G antibodies to the H. pylori hsp, whole-cell lysate, and urease (30-kDa subunit) antigens in serum were measured by a capture enzyme-linked immunosorbent assay. The levels of H. pylori hsp60 antibodies in sera collected 1 month after treatment had declined significantly, even when changes in the titers of antibodies to whole-cell and urease antigens were not apparent. These results suggest that measurement of antibodies to H. pylori hsp60 in serum is useful for the early monitoring of the effectiveness of eradication therapy.

Adult↗

PubMed2000

Balloon-occluded endoscopic retrograde ileography.

For diagnostic ileography, the authors developed balloon-occluded endoscopic retrograde ileography and performed 77 studies in 36 consecutive patients with Crohn disease. Balloon-occluded endoscopic retrograde ileography proved to be useful in visualization of minute mucosal lesions such as aphthous ulcers and lymphoid hyperplasia in the distal ileum, and satisfactory ileographic images of Crohn disease were obtained in 54 (70%) studies.

Adolescent↗

PubMed2000

Role of endogenous endotoxin on tumor necrosis factor-hypersensitivity caused by D-galactosamine challenge.

We examined the role of endotoxin in the mechanism of recombinant human tumor necrosis factor (rhTNF)-hypersensitivity caused by D-galactosamine (GalN). We used polymyxin B, an antibiotic with anti-endotoxin activity, to determine the participation of endogenous endotoxin. The glycogen and blood glucose level of rhTNF (1 x 10(4) units/mouse, i.v.)-injected mice was lower at 7 h post-intoxication than that in the control. Administration of rhTNF to GalN (700 mg/kg, i.p.)-treated mice resulted in lower levels of glycogen and blood glucose than those in animals treated with rhTNF alone. In mice pretreated with polymxin B (20 mg/kg, i.p.), the level at 7 h after rhTNF/GalN-injection was markedly increased compared to that in mice treated with rhTNF/GalN alone. The injection of a low endotoxin dose (0.1 mg/kg, i.p.) markedly decreased the rectal temperature in mice treated with rhTNF (5 x 10(3) units/mouse, i.v.) and GalN, and none of these animals survived after treatment for 18 h. These findings suggest that endogenously produced endotoxin may contribute to the extent of rhTNF-hypersensitivity caused by GalN.

Animals↗

PubMed2000

Tyrosine72 residue at the bottom of rim domain in LukF crucial for the sequential binding of the staphylococcal gamma-hemolysin to human erythrocytes.

Staphylococcal bi-component cytotoxins, leukocidin (Luk), Panton-Valentine leukocidin (PVL), and gamma-hemolysin (Hlg) consist of LukF and LukS, LukF-PV and LukS-PV, and LukF and Hlg2, respectively, and Luk and Hlg share LukF. LukF-PV can not substitute for LukF for Hlg, despite 73% identity in amino acid sequence and close similarity in the 3-dimensional structure between them. Here, we demonstrated that the absence of hemolytic activity of LukF-PV in cooperation with Hlg2 is due to the failure of the binding of LukF-PV to human erythrocytes. We identified Y72 residue at the bottom of rim domain in LukF as the crucial residue for its binding, which is a prerequisite to the subsequent binding of Hlg2 to human erythrocytes. The data obtained showed that a mutant of LukF-PV in which T71 residue was replaced by the corresponding residue of LukF, Y72, endowed LukF-PV with the binding capability to human erythrocytes which was accompanied by its hemolytic activity in the presence of Hlg2.

Amino Acid Substitution↗

PubMed2000

Effect of estrogen and progesterone on gene expression of growth regulatory molecules and proto-oncogene in vascular smooth muscle cells.

We examined influences of estrogen and progestogen on gene expression of the growth regulatory molecules: platelet-derived growth factor (PDGF), interleukin-1 (IL-1), interleukin-6 (IL-6) and proto-oncogene c-myc in vascular smooth muscle cells (VSMC) by reverse transcription-polymerase chain reaction (RT-PCR) and Southern-blotting. VSMC were exposed to estrone-sulfate (E1-S) and medroxyprogesterone acetate (MPA) to induce differentiation. E1-S inhibited the expression of PDGF-A chain, IL-1, IL-6 and c-myc mRNA, whereas MPA had no effect. Inhibition by E1-S was not affected by treatment combined with MPA. These findings suggest that estrogen modulates these growth regulatory molecules and c-myc gene expression in VSMC but not progestogen. We concluded that estrogen may have a direct atheroprotective effect through inhibition of growth regulatory factors.

Arteriosclerosis↗

PubMed2000

Hyperthyroidism in a patient with TSH-producing pituitary adenoma coexisting with thyroid papillary adenocarcinoma.

A 27-year-old woman who presented with a left thyroid nodule was found to have hyperthyroidism caused by a syndrome of inappropriate secretion of TSH. The levels of free T3, free T4 and TSH were 9.50 pg/mL, 4.05 ng/dL and 2.16 microU/mL, respectively. Magnetic resonance imaging of the head revealed a pituitary macroadenoma. The TSH response to TRH stimulation was normal and responses of other anterior pituitary hormones to stimulation tests were also normally preserved. Administration of octreotide with iodine successfully reversed hyperthyroidism prior to total resection of pituitary adenoma, which was followed by hemithyroidectomy of the left thyroid five months later. Histologically, the resected pituitary adenoma was a TSH-producing adenoma (TSH-oma) and the thyroid nodule was a papillary adenocarcinoma. Serum TSH diminished to undetectable levels immediately following pituitary adenomectomy but gradually normalized over nine months. Coexistence of a TSH-oma with thyroid cancer is very rare and only two similar cases have previously been documented. This combination raises the possibility that TSH may be involved in tumorigenesis in the thyroid gland.

Adenocarcinoma, Papillary↗

PubMed2000

Occupational dermatoses from one-component epoxy coatings containing a modified polyamine hardener.

In an electronics plant, 2 one-component epoxy coatings containing a modified polyamine hardener were used as covering materials for protecting important information on police radio circuit boards. The resinous parts of the coatings consisted of epoxy resins based on diglycidyl ether of bisphenol F. The hardener was a dimethylaminopropylamine (DMAPA)-epoxy adduct and contained about 0.16% free DMAPA. Of 105 workers, 17 (16%) were diagnosed to have work-related dermatitis but were not patch tested. The hands were the commonly affected region (13 out of 17 cases). The latent period of dermatitis was very short (mean 21.5 days). The work-related dermatoses were closely related to the type of work and working periods. In the present study, hand protection and the introduction of automation have been demonstrated to be useful for the prevention of epoxy coating dermatitis.

Adult↗

PubMed2000

A novel chiral stationary phase in HPLC: optical resolution of racemic amino compounds by (1-->6)-2,5-anhydro-3,4-di-O-ethyl-D-glucitol bound on silica gel.

[(1-->6)-2,5-Anhydro-3,4-di-O-ethyl-D-glucitol]-bound silica gel (CSP 4a), which was prepared by a two-step reaction, was used as a chiral stationary phase in high-performance liquid chromatography. The chiral recognition ability of the CSP 4a for racemates was examined using aq. NaClO4 (pH 2) and aq. NaClO4 (pH 2)/CH3CN as the eluents. For the resolution of amino acids and amino acid methyl esters, the D-isomers were eluted first. The separation factors of many of the racemates were 1.1-1.4, and the resolution factors were 0.59-7.75. This stationary phase showed a relatively high-resolving power toward compounds having a bulky substituent on the chiral carbon, such as phenylglycine and 1-(1-naphthyl)ethylamine.

Journal Article↗

PubMed1999

Localization of syndecan-1 in human gastric mucosa associated with ulceration.

Syndecans, cell surface heparan sulphate proteoglycans, are known to function as cell adhesion molecules and as a co-receptor for heparin-binding growth factors that have important roles in tissue homeostasis and repair, but the localization of syndecans in gastric mucosa and their role in gastric ulcer healing are not known. The licalization of syndecan-1, a subfamily protein of syndecans expressed on epithelial cells, was studied in 12 surgically resected human stomachs containing an ulcer or early scar tissue. Localization of syndecan-1 was detected both by immunohistochemistry and by in situ hybridization In non-ulcer sites of gastric mucosa, syndecan-1 protein was expressed at the basolateral surface of foveolar epithelial cells and the cells of intestinal metaplasia, and at the cell surface of stromal plasma cells. In addition, positive dots of syndecan-1 were found in the cytoplasmic area of parietal cells. Foveolar epithelial cells at active stage ulcer margins showed nearly the same intensity of staining as those at non-ulcer site mucosa. By contrast, enhanced staining was obtained in elongated regenerative foveolar cells at the healing ulcer margins and the early scar tissues. The migrating cells on ulcer floors also expressed syndecan-1 protein. The expression sites of syndecan-1 mRNA mostly coincided with those of syndecan-1 protein. These results suggest that syndecan-1 participates in cell adhesion mainly at the foveolar epithelium and plays a role in the healing of gastric ulcers by interacting with heparin-binding growth factors.

Gastric Mucosa↗

PubMed1999

Exposure-response relationships in rhinitis and conjunctivitis caused by methyltetrahydrophthalic anhydride.

OBJECTIVE: To examine exposure-response relationships in the occurrence of symptoms of the eyes and airways in workers exposed to methyltetrahydrophthalic anhydride (MTHPA). METHODS: A population of 111 workers from 2 condenser plants (A and B) using epoxy resin with MTHPA underwent a questionnaire survey and serology investigations, and data obtained on 95 subjects in assembly and inspection lines were analyzed for this study. RESULTS: In all, 24 (65%) of 37 workers in plant A and 38 (66%) of 58 workers in plant B had positive MTHPA-specific IgE. The air levels of MTHPA detected in assembly and inspection lines were higher in plant A than in plant B (geometric mean 25.5-63.9 and 4.93-5.49 microg/m3, respectively). IgE-sensitized workers in each plant had significantly (P < 0.05) more complaints regarding the eyes and nose than did unsensitized workers, suggesting that there is an IgE-mediated mechanism in most of these symptoms. The sensitized workers in plant A had higher frequencies for symptoms of the eyes, nose, and pharynx than did those in plant B (P < 0.02). Furthermore, only 15% of persons often displayed work-related symptoms among the 20 symptomatic workers in plant B as compared with 73% of the 26 symptomatic workers in plant A (P < 0.0001). These results can be explained by the difference in the MTHPA levels measured in the lines between the two plants. In plant B the minimal level of MTHPA that was associated with work-related symptoms was 15-22 microg/m3, which was lower than the geometric mean levels detected in assembly and inspection lines in plant A. CONCLUSIONS: These results suggest that MTHPA exposure at levels above 15 microg/m3 should be avoided to prevent the development of occupational allergic diseases in most workers.

Adult↗

PubMed1999

Long-distance effects of site-directed mutations on backbone conformation in bacteriorhodopsin from solid state NMR of [1-13C]Val-labeled proteins.

We have recorded 13C cross-polarization-magic angle spinning and dipolar decoupled-magic angle spinning NMR spectra of [1-13C]Val-labeled wild-type bacteriorhodopsin (bR), and the V49A, V199A, T46V, T46V/V49A, D96N, and D85N mutants, in order to study conformational changes of the backbone caused by site-directed mutations along the extracellular surface and the cytoplasmic half channel. On the basis of spectral changes in the V49A and V199A mutants, and upon specific cleavage by chymotrypsin, we assigned the three well-resolved 13C signals observed at 172.93, 172.00, and 171. 11 ppm to [1-13C]Val 69, Val 49, and Val 199, respectively. The local conformations of the backbone at these residues are revealed by the conformation-dependent 13C chemical shifts. We find that at the ambient temperature of these measurements Val 69 is not in a beta-sheet, in spite of previous observations by electron microscopy and x-ray diffraction at cryogenic temperatures, but in a flexible turn structure that undergoes conformational fluctuation. Results with the T46V mutant suggest that there is a long-distance effect on backbone conformation between Thr 46 and Val 49. From the spectra of the D85N and E204Q mutants there also appears to be coupling between Val 49 and Asp 85 and between Asp 85 and Glu 204, respectively. In addition, the T2 measurement indicates conformational interaction between Asp 96 and extracellular surface. The protonation of Asp 85 in the photocycle therefore might induce changes in conformation or dynamics, or both, throughout the protein, from the extracellular surface to the side chain of Asp 96.

Bacteriorhodopsins↗

PubMed1999

Hyperechoic renal papillae as a physiological finding in neonates.

AIM: The increased echogenicity of medullary pyramids in neonates and children is poorly understood. Hence we conducted a prospective ultrasound study of the kidneys of neonates and fetuses. Hence we conducted a prospective ultrasound study of the kidneys of neonates and fetuses. PATIENTS AND METHODS: Ultrasound images of kidneys in neonates and fetuses in late pregnancy were analysed. RESULTS: Thirteen percent of the studied neonates showed hyperechogenicity in the renal papillae that disappeared spontaneously within 1 week, although no hyperechoic papillae were seen in any of the fetuses. Urine volume of the neonates with hyperechogenicity was significantly less than that of those without it. CONCLUSION: The fact that no hyperechoic findings appeared before the 34th week of gestation suggests that maturation of renal tubules and ability to concentrate urinary substances were contributing factors. Because only the tips of the pyramids were hyperechogenic, however, the term hyperechoic papillae would seem more appropriate than hyperechoic pyramids, the term generally used today.

Birth Weight↗

PubMed1999

Gastric ulcers in SCID mice induced by Helicobacter pylori infection after transplanting lymphocytes from patients with gastric lymphoma.

BACKGROUND & AIMS: Several studies have indicated that host factors are important in Helicobacter pylori-induced gastroduodenal diseases. We examined the pathological role of host immune responses in H. pylori infection by reconstituting components of the human immune system into severe combined immunodeficient (SCID) mice by transplantation of peripheral blood mononuclear cells (PBMCs) from H. pylori-infected patients. METHODS: PBMCs obtained from patients with mucosa-associated lymphoid tissue (MALT) lymphoma were injected intraperitoneally into SCID mice, designated MALToma-hu-SCID mice. One month after transplantation, H. pylori was administered orally to the mice. The mice were killed and examined for pathological changes and immunologic features. RESULTS: Human lymphocytes were detected in hu-SCID mice, and T- and B-cell functions were preserved for 1 month. Administration of H. pylori led to gastric ulcers with bleeding in the MALToma-hu-SCID mice. The gastric mucosa of control mice injected with Escherichia coli or transplanted with PBMCs from patients with peptic ulcers or gastritis or from healthy volunteers showed no pathological changes. CONCLUSIONS: Host immune responses against H. pylori appear to be involved in the development of gastric ulcers in patients who have MALT lymphoma.

Animals↗

PubMed1999

Cavitary lung cancer with an aspergilloma-like shadow.

A 66-year-old man who complained of cough and haemoptysis had a cavitary lesion with the meniscus sign in the right lower lung field on his chest X-ray and CT scan. He had smoked 40 cigarettes daily, for about 46 years. Initially, he was diagnosed with aspergilloma and given an antifungal agent. After 2 months, the cavitary lesion showed a slight irregularity of the inner border. The walls were irregularly thickened and were surrounded by infiltrative densities compared with the previous chest radiograph. Enlargement of right hilar and mediastinal lymph nodes was also observed. The fungus ball-like shadow was fixed on the anterior wall of the cavity and its position was not altered with the patient's movements. These radiographic findings led to suspicion that the lesion might be malignant. Transbronchial lung biopsy of the cavity wall and CT guided needle aspiration biopsy of the fungus ball-like lesion were performed. Microscopic examination revealed a squamous-cell carcinoma in both the cavity wall and the fungus ball-like lesion. There was no evidence of fungal elements. In conclusion, the meniscus sign is most often associated with benign diseases such as aspergilloma, however, one should remember that carcinoma may be a cause.

Aged↗

PubMed1999

Daily pattern of energy metabolism in cirrhosis.

The daily pattern of energy expenditure and the oxidation rates of carbohydrates, fats, and protein were evaluated by indirect calorimetry in 18 control subjects (Group 1) and 34 cirrhotic patients who were divided into Groups 2a and 2b showing indocyanin green retention rates at 15 min of <30% and 30% or more, respectively. The ratio of resting energy expenditure to basal energy expenditure (%REE) was higher in the cirrhotic patients than in the controls at 8:30 AM and 2:30 PM. The oxidation rates of carbohydrates and fats under fasting conditions in Group 2b patients were respectively lower, and higher than in Group 1 and 2a patients. After the subjects ate, glucose became the substrate preferentially metabolized, and the proportion of fat metabolized was reduced from 82.9+/-5.1% to 43.9+/-21.9% and from 70.7+/-14.1% to 46.8+/-13.9% in the patients with advanced and less advanced cirrhosis, respectively, and from 59.4+/-27.2% to 48.4+/-18.5% in the controls. The fasting concentrations of non-esterified fatty acids in Group 2b were also significantly higher than those in the Group 1 and Group 2a patients. After eating, these concentrations fell and reached similar levels in the patients and controls. These data indicated that the patients with cirrhosis developed the catabolic state of starvation in the morning because of a lack of glycogen stores. Therefore, frequent meal supplementation to prevent early-onset starvation and energy deficiency may be advisable in such patients to maintain a well-nourished condition.

Aged↗

PubMed1999

Effects of 16 weeks of treatment with tibolone on bone mass and bone mechanical and histomorphometric indices in mature ovariectomized rats with established osteopenia on a low-calcium diet.

Tibolone is a synthetic steroid with tissue-specific estrogenic, progestogenic, and androgenic properties. The therapeutic effects of tibolone on bone mass and strength, bone metabolic markers, and indices of histomorphometry were investigated in ovariectomized (ovx) rats on a low (0.1%)-calcium diet in comparison with 17alpha-ethynylestradiol (EE) or 1alpha-hydroxyvitamin D3 [1alpha(OH)D3]. Tibolone (0.1-3 mg/kg/day), EE (0.1 mg/kg/day), or 1alpha(OH)D3 (0.5 microg/kg/day) was administered orally once a day for 16 weeks, starting 12 weeks after ovariectomy, when the bone mineral density (BMD) of lumbar vertebrae (L4-5) and femur (global, proximal, and distal regions) had already been decreased by the combination of ovariectomy and low dietary calcium. The BMD of the lumbar vertebrae and the femur were higher in the groups treated with tibolone, EE, or 1alpha(OH)D3 than in the ovx control group. The BMD of the mid-diaphysial regions of femur and tibia, which consist mainly of cortical bone, were decreased 28 weeks after ovariectomy in the ovx control group. The BMD of the mid-diaphysial femur was higher in the groups treated with 1alpha-(OH)D3, and the BMD of mid-diaphysial tibia was higher in the groups treated with tibolone or 1alpha(OH)D3 than in the ovx control group. Like BMD, the compressive strength of the vertebral body of L2, corrected for the volume of each individual vertebra tested, was higher in the groups treated with tibolone, EE, or 1alpha(OH)D3 than in the ovx control group. Trabecular bone volume and trabecular number were reduced 12 and 28 weeks after ovariectomy but there was no change in trabecular thickness. These reduced indices were increased in the groups treated with tibolone, EE, or 1alpha(OH)D3 when compared with the ovx control group. Tibolone or EE decreased serum levels of osteocalcin and bone alkaline phosphatase and urinary levels of deoxypyridinoline and pyridinoline compared with the ovx control group. Furthermore, tibolone or EE decreased the mineralizing surface and bone formation rate as well as the osteoclast surface and osteoclast numbers. 1Alpha(OH)D3, however, did not affect these serum and urinary parameters. These data suggest that tibolone suppresses the accelerated bone turnover induced by a combination of ovariectomy and low dietary calcium, and indicate that tibolone may be a potentially useful drug for the treatment of postmenopausal osteoporosis.

Absorptiometry, Photon↗