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Biomedical subjects

K Segawa

Publications and source records attributed to K Segawa.

At least 91 records · Page 5Linked to original sources
PubMed1992

Comparative effects of loop diuretics on AVP-receptor binding and AVP-sensitive adenylate cyclase activity.

The effects of loop diuretics (azosemide, ethacrynic acid and furosemide) on arginine vasopressin (AVP) receptor-adenylate cyclase components were compared in rat renal basolateral membranes. AVP binding was inhibited by these loop diuretics at concentrations above 10(-4) M. At the IC50 of azosemide and ethacrynic acid, the Kd values were significantly increased, while the Bmax values remained unchanged. These findings indicate an inhibitory effect of loop diuretics at high concentrations on the AVP binding to its receptors. Both the basal (AVP-unstimulated) and AVP-stimulated cyclic AMP productions were also inhibited by addition of these drugs. The inhibitions of the AVP binding and AVP-sensitive adenylate cyclase activity were dose-dependent. The above findings suggest that loop diuretics, especially azosemide and ethacrynic acid, can inhibit the basal and AVP-sensitive adenylate cyclase activities directly and also indirectly via the AVP receptor, at least in part. Comparing the loop diuretics, azosemide exerts a similar effect to ethacrynic acid, and they have a more potent antagonistic effect than furosemide with respect to AVP adenylate cyclase activation.

Adenylyl Cyclases↗
PubMed1992

Prevalence of gallbladder polyps among apparently healthy Japanese: ultrasonographic study.

The prevalence of gallbladder polyps was investigated in apparently healthy Japanese who underwent abdominal ultrasonography as part of their health screening examination. The polyps found were differentiated from gallstones, adenomas, or carcinomas as much as possible, and were considered to be cholesterol polyps. The prevalence of such gallbladder polyps was higher among males in every decade of age evaluated. The subjects with gallbladder polyps were more obese than the control group without gallbladder polyps, on abdominal ultrasonograms. The prevalence of gallbladder polyps rose in accordance with a rise in obesity index. At each range of obesity index, the prevalence of gallbladder polyps was higher among males. The prevalence of gallbladder polyps was highest among the middle-aged (40- and 50-yr-old) males, similar to the curve of the obesity index. In females, the obesity index increased with age, with no accompanying rise in the prevalence of gallbladder polyps. These data suggest that obesity contributes to the formation of cholesterol polyps of the gallbladder.

Adolescent↗
PubMed1992

[A case of psittacosis with migratory infiltrates].

A 56-year-old man with fever, headache, cough and sputum was admitted to another clinic. Chest X-ray examination revealed infiltrates in the upper lobe of the right lung. Cefem and aminoglycoside therapy was not effective, and the infiltrates migrated from the right upper lobe to the right middle and lower lobes and then to the left lung. He was transferred to our clinic, and laboratory data showed that CRP was 6+; ESR, 119 mm/1 h; WBC, 3000/mm3; and CAR, 512. The tentative diagnosis of atypical pneumonia was based on the positive agglutination test for Legionella pneumophila, and treatment with erythromycin, minocycline and rifampicin resulted in alleviation of symptoms and resolution of the infiltrates in the lungs. Complement fixation titer for Chlamydia was 128 at admission and was elevated to 512 after 2 weeks. Indirect fluorescent antibody for Legionella was negative. Transient liver dysfunction was also observed.

Humans↗
PubMed1991

Induction of CAT gene expression on a plasmid vector (L factor) by retinoic acid in mouse embryonal carcinoma (F9) cells.

We reported previously that composite DNA constructed from a mammalian plasmid (L factor) and foreign gene can be reestablished as a plasmid in mouse embryonal carcinoma (F9) cells after transfection and the plasmid-bearing F9 cells undergo normal in vitro differentiation in response to retinoic acid, an inducer for F9 cell differentiation. We constructed F9 cells bearing plasmidal L factor DNA in which a reporter (chloramphenicol acetyltransferase; CAT) gene was placed under the control of a differentiation-responsive viral (Moloney murine leukemia virus or simian virus 40) enhancer-promoter. When such plasmid-bearing cells were treated with retinoic acid, the CAT gene was inducibly expressed. These results indicate that mammalian gene expression can be studied with the plasmidal expression vector which is structurally dissociated from complex chromosomes.

Animals↗
PubMed1991

Effect of co-administration of granulocyte colony-stimulating factor on interferon therapy.

The effect of co-administration of granulocyte colony-stimulating factor (G-CSF), as an antineutropenia agent, on interferon therapy was examined in a mouse model, in anticipation of an enhancement of interferon efficacy, because neutrophils induced by G-CSF are thought to act as antitumor effectors. G-CSF was intraperitoneally co-administered with human interferon alpha A/D (IFN) on Day 6 to Day 10 after intradermal inoculation of Meth A fibrosarcoma. Although the co-administration of G-CSF could protect against neutropenia and leukopenia induced by IFN, it did not enhance the regression of tumor, and rather reduced the prolongation of survival time and the long-term survival incidence of IFN therapy. The subsequent in vitro study showed that the antiproliferative activity of peripheral blood leukocytes from Meth A-bearing mice given both IFN and G-CSF was much weaker than that of mice given IFN alone. Whether the observed nullifying effect of G-CSF on IFN therapy is also the case with tumors other than Meth A is open to further study.

Animals↗
PubMed1991

In vivo tumor growth enhancement by granulocyte colony-stimulating factor.

The intraperitoneal administration of human recombinant granulocyte colony-stimulating factor (G-CSF) enhanced the growth of intradermally inoculated tumor in mice; in a Meth A fibrosarcoma model, G-CSF administration significantly shortened the latency before tumor appearance, accelerated the increase of tumor size, shortened the survival time of tumor-bearing mice and increased the incidence of lethal tumor growth. A similar growth-enhancing effect of G-CSF was observed in models employing Meth 1 fibrosarcoma, colon carcinoma 26, and L1210 leukemia, although not all the effects were statistically significant. In vitro study showed that G-CSF did not enhance Meth A growth in suspension culture or in soft agar. These data suggest that G-CSF enhances the Meth A growth not directly but through the mediation of host factors. The accumulation of neutrophils was histologically observed in the tumor nodule, the blood, and the spleen in mice given G-CSF repeatedly. The spleen cells and the peripheral blood leukocytes of G-CSF-injected mice enhanced Meth A growth in vitro as compared with those of mice injected with physiological saline. These results suggest the possibility that the in vivo growth of tumor cells was enhanced by G-CSF-induced overproduction of cells including neutrophils.

Animals↗
PubMed1991

Clinical course of multiple primary oral cancer: three of 13 cases with second primary tumor.

Of 124 patients with oral squamous cell carcinomas treated during the past 14 years, 13 developed second primary cancers with clinical symptoms in the same tissues or in organs different from those of the initial lesions during follow-up. The second primary tumors also appeared in the oral cavity in 3 of the patients, the hypopharynx in 1, the esophagus in 2, the stomach in 2, the colon in 1, the thyroid gland in 2 and the lung in 2. Of the 3 patients with second tumors in the oral cavity, 1 underwent surgery after chemo- and radiotherapy and 2 underwent laser surgery or chemo- and radiotherapy only. The second primary cancers appeared on the contralateral or ipsilateral side, completely separate from the sites of the primary lesions during a period of 1 to 3 years. One patient with triple cancers involving the oral cavity, esophagus and hypopharynx is still alive after 15 years. The other two patients died of cervical or lung metastases after 3 years.

Adult↗
PubMed1991

Effect of cimetidine on the mucosal hydroxyproline content of rat gastric lesions induced by compound 48/80.

Extensive gastric mucosal lesions developed in rats after the administration of compound 48/80 at a dose of 0.75 mg/kg daily for 3 days. The hydroxyproline content of gastric mucosa was significantly increased 4 h after the last injection of compound 48/80, and subsequently decreased as the lesions healed. Treatment with cimetidine (CAS 51481-61-9) at a dose of 50 mg/kg (twice a day for 3 days) did not affect either the development or the healing of the compound 48/80-induced gastric lesions. However, the increase in mucosal hydroxyproline content was significantly reduced by treatment with cimetidine. This fact suggests that cimetidine might have an inhibitory effect on the regeneration of collagen in gastric mucosa.

Animals↗
PubMed1991

Estimate of gastric acid output by evaluation of fasting gastric juice collected endoscopically.

Using an endoscope we collected fasting gastric juice for estimation of gastric acid in subjects examined by upper gastrointestinal endoscopy. Subjects were 53 in- and out-patients (46 males and 7 females) at our hospital. Seventy-five gastric secretory studies were performed in this population before and after stimulation by tetragastrin, following the guidelines of The Japanese Society of Gastroenterology and using a specially devised endoscope of narrow caliber under direct vision. Acid in fasting gastric juice was correlated with basal acid output (BAO) and with maximal acid output (MAO). There was a statistically significant correlation between them. Thus, an estimation of gastric acid secretion can be obtained from the fasting gastric juice which we usually aspirate and discard during the routine endoscopic examination.

Adolescent↗
PubMed1991

[Examination of endoscopical ultrasonography (EUS) on carcinoid tumors of gastrointestinal tract].

In order to clarify the usefulness of EUS in the diagnosis of gastrointestinal carcinoid tumor, we examined 15 patients, who had carcinoid tumors of gastrointestinal tract (stomach: 5, duodenum: 2, rectum: 8), on the diagnosis in quality and depth by comparing endoscopical ultrasonography (EUS) with resected specimen. Carcinoid tumors of gastrointestinal tract were detected as homogenous hypoechoic tumors with sharp border in all site by EUS. Especially, it was characteristic that 14 of the 17 lesions (82%) which invaded into submucosa were mainly located in the third layer, and the second layer covered the tumor at the foot, and near the top, it touched the tumor and got indistinct. We decided the depth of invasion by comparing the hypoechoic tumor with normal structure of 5 layers. The accuracy rate was 88%. In conclusion, EUS was thought to be useful in the diagnosis and choice for treatment of carcinoid tumors of gastrointestinal tract.

Adult↗
PubMed1991

[An immunohistopathological study on intrahepatic distribution of HBeAga/b in biopsied chronic type B hepatitis].

In order to evaluate the role of a expression of HBV-associated, we investigated histological and cytological distribution of HBeAga, HBeAgb, and HBcAg by immunoperoxidase procedure using monochronal antibodies. Materials submitted for this study were needle biopsied specimens obtained from 41 chronic carriers and serial paraffin sections were used for the immunohistological study. The localization of HBeAga/b antigens was limited in hepatocellular nuclei, and hepatocellular cytoplasm was HBeAg negative, HBeAg was detected in 11 cases (33%) of 33 cases with chronic active hepatitis (CAH) and in 5 cases (63%) of 8 cases with chronic inactive hepatitis (CIH). Among the HBeAg positive 16 cases, HBeAgb was demonstrated in 15 cases, however, HBeAga was revealed only each one case of CAH and CIH, respectively. Most of HBeAg positive cells were distributed in the peripheral zone of the hepatic lobules while the positive cells were found in central to midzonal zones of 3 cases CAH and one case of CIH. All in histopathologically HBeAga/b positive cases were also HBeAg positive serologically. On the other hand, in HBeAg sero-positive patients, histological positive rate of HBeAga/b was in 33% in CAH and 50% in CIH.

Biopsy↗
PubMed1990

Prominent stacking interaction with aromatic amino acid by N-quarternization of nucleic acid base: X-ray crystallographic characteristics and biological implications.

In order to investigate the mode of interaction between the N-quarternized cytosine base and the aromatic amino acid, the crystal structure of the 3-methyl-cytidine-5'-monophosphate:tryptamine complex was analyzed by X-ray diffraction. The complex crystals were stabilized by extensive hydrogen bond formations in which eight independent water molecules per complex pair participated. A prominent stacking interaction, characterized by a parallel alignment of both rings with a separation distance of ca. 3.4 A, was observed between the cytosine base and the indole ring. Combining the present results with X-ray crystallographic data on the adenine--and guanine--aromatic amino acid interactions, we summarize the structural characteristics observed in the stacking interaction of the N-quarternized nucleic acid base with the aromatic amino acid and discuss their biological implications, especially in connection with the significance of N-protonation of nucleic acid base for selective recognition by protein.

Adenine↗
PubMed1990

Possible role of cementoblasts in the resorbant organ of human deciduous teeth during root resorption.

Human deciduous teeth undergoing physiologic root resorption were extracted and fixed with a mixture of formaldehyde and glutaraldehyde and processed for scanning (SEM) and transmission (TEM) electron microscopy, and for acid (ACPase) and alkaline phosphatase (ALPase) cytochemistry. The resorbant organ, rich in odontoclasts, cementoblasts, fibroblasts, and macrophages, formed prominent resorption lacunae in root dentin. SEM observations of resorption lacunae treated with trypsin solution showed islands of newly-formed cementum matrix in part of the resorbing dentin surfaces. Such cementum consisted of bundles of densely-arranged collagen fibrils and, in part, contained forming cementocytic lacunae and canaliculi. Active cementoblasts adjacent to odontoclasts on resorbing dentin surfaces showed cuboidal outlines and were characterized by the presence of numerous cisterns of rough endoplasmic reticulum, well-developed Golgi complexes, secretion granules, and many mitochondria. They sometimes formed a thin layer of cementoid and/or cementum matrix upon the resorbing dentin surface. These cementoblasts had ACPase-positive lysosomes in the cell bodies and exhibited intense ALPase activity along the plasma membranes of whole cell surfaces. These results suggest that, during root resorption, 1) active cementoblasts are present adjacent to active odontoclasts and 2) these cementoblasts are involved in remodeling the resorbing dentin surfaces.

Acid Phosphatase↗
PubMed1990

Effects of cimetidine and omeprazole on angiogenesis in granulation tissue of acetic acid-induced gastric ulcers in rats.

We investigated the effects of cimetidine and omeprazole on angiogenesis in granulation tissue and on the healing of gastric ulcers induced by acetic acid in rats. Either cimetidine (50 or 100 mg/kg) or omeprazole (10 or 20 mg/kg) was orally administered once daily for 9 consecutive days from the day following ulcer production. The ulcer index on the 10th and 30th days after ulcer production, and the extent of angiogenesis on the 10th day were examined. Cimetidine dose-dependently decreased the extent of angiogenesis on the 10th day, whereas the ulcer index on the 10th days was not significantly different between cimetidine-treated and control rats. The ulcer index of the groups treated with cimetidine during the initial 9-day period was increased compared with the control group on the 30th day. In contrast, oral omeprazole did not affect angiogenesis on the 10th day and decreased the ulcer index on both the 10th and 30th days. These results suggest that oral cimetidine may inhibit angiogenesis in ulcer granulation tissue possibly via the blocking of histamine H2 receptors and this may be one cause of delayed ulcer healing.

Acetates↗
PubMed1990

Nonlethal G0-ts mutant tsJT60 becomes lethal at the nonpermissive temperature after transformation: a hint for new cancer chemotherapeutics.

tsJT60 is a nonlethal temperature-sensitive (ts) mutant of a Fischer rat cell line (3Y1) classified as a G0 mutant; i.e., the ts defect is not expressed within the cell growth cycle but is expressed only between the G0 and S phase. tsJT60 clones transformed with oncogenes such as adenovirus E1A, polyoma large T, polyoma middle T, v-Ki-ras, and LTR activated c-myc, or with a chemical carcinogen N-methyl-N'-nitro-N-nitrosoguanidine, grew well at 34 degrees C. However, most of these clones grew slowly at 40 degrees C, producing many floating dead cells, and some clones were killed at 40 degrees C. When they were cultured under conditions inadequate for growth of untransformed cells, such as high cell density or serum restriction, they were killed at 40 degrees C. These and previous results from SV40- and adenovirus-transformed tsJT60 clones favour the idea that transformed tsJT60 cells occasionally enter the G0 phase and are metabolically imbalanced at 40 degrees C during self-stimulation from the G0 to S phase. We propose that a drug which exclusively block, G0-G1 transition would be cytocidal to transformed cells but cytostatic to normal cells.

Adenovirus Early Proteins↗
PubMed1990

Immunologic analysis of cerebrospinal fluid lymphocytes in Vogt-Koyanagi-Harada disease.

In this study, we focused upon the immunologic aspects of Vogt-Koyanagi-Harada disease (VKH) by comparing the cytotoxic activity of peripheral blood leukocytes (PBL) to that of cerebrospinal fluid leukocytes (CSFL) against the human melanoma cell line (P-36) and the human cervical carcinoma cell line (HeLa-S3). The PBL from patients with VKH showed significant cytotoxic activity against P-36 (P less than 0.01), but did not show cytotoxic activity against HeLa-S3. The CSFL showed significantly weaker cytotoxic activity against P-36 compared to that of PBL (P less than 0.02). We also analyzed the cell membrane surface markers applying monoclonal antibodies on PBL and CSFL. The percentage of OKT8+ (CD8: T cytotoxic/suppressor lymphocytes) cells was significantly lower in CSFL than in PBL (P less than 0.05). There was a tendency toward a higher percentage of HLA-DR+ cells (B lymphocytes, monocytes, macrophages, and activated T lymphocytes) and a higher ratio of OKT4+/8+ cells (CD4/CD8: T helper/inducer lymphocytes/T cytotoxic/suppressor lymphocytes) in CSFL from patients with VKH than in their PBL (P less than 0.1).

Adolescent↗