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Biomedical subjects

A Ito

Publications and source records attributed to A Ito.

At least 433 records · Page 24Linked to original sources
PubMed1995

Elevated serum growth hormone accelerates gastric tumorigenesis in F344 rats after treatment with N-methyl-N-nitrosourea in their drinking water.

We examined the effects of growth hormone on tumorigenesis in F344 rats treated with N-methyl-N-nitrosourea (MNU). Four-week-old male F344 rats were exposed to 100 ppm MNU in their drinking water for 15 weeks. Thereafter Group II animals received 100 microCi/100 g body weight of 131I (radiothyroidectomy, Tx) injected i.p. and Group III rats were implanted with pituitary tumors (MtT) secreting growth hormone while Group I received no further treatment after MNU. Non-carcinogen control animals received MtT, Tx or no treatment. Animals were killed at 39 weeks after starting MNU administration. Gastric tumors were present in 13 of 31 (43%), 15 of 32 (47%) and 17 of 32 (53%) rats in Groups I to III, respectively. All tumors were of well-differentiated type. Spinal cord tumors appeared in 15 of 31 (47%) in Group I, 10 of 32 (32%) in Group II and 10 of 32 (32%) in Group III, most being malignant schwannomas. Thymic lymphomas also appeared in 10 of 31 (32%), 5 of 32 (16%) and 6 of 32 (19%) animals in Groups I to III, respectively. There were no significant differences among the groups. However, tumors in Group III developed significantly earlier than in Groups I or II. This was mainly due to gastric tumors, and cumulative incidence curves for spinal cord tumors or thymic lymphomas were similar in all groups. The results indicate that gastric tumors induced by MNU in F344 male rats are influenced by elevated levels of growth hormone.

Animals↗
PubMed1995

Progesterone enhancement of stomach tumor development in SD rats treated with N-methyl-N'-nitro-N-nitrosoguanidine.

The effects of chronic progesterone treatment on gastric tumorigenesis were examined in 6-week-old male SD rats. The rats were castrated, progesterone or testosterone pellets were implanted, and, starting one week after the operation, 100 mg/liter of N-methyl-N'-nitro- N-nitrosoguanidine (MNNG) was administered in the drinking water for 16 weeks. Every 2 months the pellets were changed. Group 1 animals received castration plus MNNG while Groups 2 and 3 also received progesterone and testosterone, respectively. In the Group 4 case, progesterone and testosterone were administered alternately for 2-month periods and in Group 5 MNNG was given to intact animals. All survivors were killed one year after the start of MNNG treatment. In Group 1 the incidence of gastric tumors was significantly decreased as compared with the Group 5 value. The Group 2 incidence, in contrast, was similar to that in Group 5, and the size of the observed gastric tumors was massively increased. The area of the pyloric gland mucosa was also greater than in other groups. Testosterone treatment was associated with a less pronounced increase in tumor size and a recovery in incidence. The results indicate that progesterone may exert a promoting influence on gastric tumor development.

Animals↗
PubMed1995

Expression of vascular permeability factor (VPF/VEGF) messenger RNA by plasma cells: possible involvement in the development of edema in chronic inflammation.

Edema occurs in some types of chronic inflammation such as nasal polyps, uterine cervical polyps and gastric hyperplastic polyps. However, the factors or cellular components involved in the development of edema in chronic inflammation remain to be clarified. Recently, the gene encoding vascular permeability factor (VPF) or vascular endothelial growth factor (VEGF) and the genes encoding its receptors (kinase insert domain-containing receptor (KDR) and fms-like tyrosine kinase-1 [fit-1]) have been cloned. VPF/VEGF induces vascular hyperpermeability and vascular endothelial proliferation through KDR or fit-1 receptors. As there is a possibility that VPF/VEGF may play a role in the development of edema in chronic inflammation, we examined the messenger (m) RNA expression of VPF/VEGF and its receptors in nasal polyp tissues, which is an example of chronic inflammation with remarkable edema. Using northern blotting, all nasal polyp tissues examined expressed mRNA of VPF/VEGF and KDR. In situ hybridization revealed that VPF/VEGF mRNA-expressing cells were scattered in the edematous stroma of nasal polyps. In the adjacent sections, these cells showed the morphological features of plasma cells and expressed mRNA of immunoglobulin light chains. Human B cell leukemia and plasmacytoma cell lines expressed VPF/VEGF mRNA but human mast-cell leukemia and T cell leukemia cell lines did not. The alternatively spliced pattern of VPF/VEGF transcripts observed in nasal polyp tissues was consistent with that in plasmacytoma cell lines. Taken together, the VPF/VEGF mRNA-expressing cells in nasal polyps appeared to be plasma cells, suggesting that plasma cells may play an important role in the development of edema in chronic inflammation through the production of VPF/VEGF.

Base Sequence↗
PubMed1995

[Study on reverse transcriptase inhibiting antibody in plasma of HIV-1 seropositive subjects].

Reverse transcriptase (RT) inhibiting antibody in a series of plasma of HIV-1-seropositive subjects was quantitatively measured by poly A-linked colorimetric microtiter plate assay. The plasma were obtained from 6 asymptomatic carrier (AC)s and from 3 patients who progressed to AIDS. They had been followed 29-51 months. RT inhibiting antibody levels in the plasma were measured by inhibition assay against HTLV-IIIB RT activity. In five of the 6 AC cases, RT inhibiting antibodies in the serial plasma maintained high levels, and 50% inhibiting titers of the serial plasma did not decrease throughout the observation periods (45-51 months). HIV isolation from peripheral blood mononuclear cell (PBMC) of these 5 ACs did not succeed, and HIV p24 antigens were not detected in the plasma. In one AC case (046) RT inhibiting antibody levels gradually decreased after 48 months. In this case, HIV p24 antigen was not detected in the serial plasma throughout the observation period (48 months), but HIV was isolated from PBMC after 27 months. On the other hand, RT inhibiting antibody levels in the serial plasma of all 3 patients who progressed to AIDS gradually decreased in observation periods (29-35 months). HIV strains were isolated from these 3 cases. These results suggest that reduction of RT inhibiting antibody levels correlate well with the success of HIV isolation and with progression of clinical manifestation.

AIDS Serodiagnosis↗
PubMed1995

Differentiation of human immunodeficiency virus type 1 (HIV-1) infections with HIV-2-cross-reacting antibody from mixed infections with HIV-1 and HIV-2 by serological absorption test.

The interpretation of dual seroreactivity with human immunodeficiency virus type 1 (HIV-1) and HIV-2 in blood samples is a serious problem facing AIDS researchers worldwide. Some samples of sera from HIV-1-infected patients showed a serological cross-reaction with HIV-2, causing confusion regarding the serodiagnosis. Therefore, we tried to differentiate these serum samples from those containing real mixed infections with both types of virus. Sera from patients with HIV-1 infections with HIV-2 cross-reacting antibody in Japan were distinguished from sera from patients with mixed infections with HIV-1 and HIV-2 in West Africa by our serological cross-absorption test, which proved to be highly specific and useful for serodiagnosis.

AIDS Serodiagnosis↗
PubMed1995

Effects of L-arginine analogues on vasomotion of isolated porcine coronary arteries.

L-Arginine analogues have been widely used to examine the role of endothelium-derived nitric oxide (NO) in vascular responses; however, the effects of the agents on coronary vasomotion are not fully understood. In this study, we examined the effects of the analogues on vasomotion of isolated porcine coronary arteries. Strips of the porcine coronary artery were suspended for isometric tension recording in Krebs-Henseleit solution. L-Arginine analogues, N omega-nitro-L-arginine methyl ester (L-NAME, 10(-9)-10(-3) M), NG-monomethyl-L-arginine (L-NMMA, 10(-9)-10(-3) M), and NG-nitro-L-arginine (L-NNA, 10(-9)-10(-3) M), caused dose-dependent contractions, which were greater in strips with than in those without endothelium. Those endothelium-dependent contractions were almost abolished by indomethacin (10(-5) M) and FeCl2 (10(-3) M). The latter reduces prostaglandin H2 to 12-heptadecatrienoic acid, which has no vasoconstrictor effect. These results indicate that the L-arginine analogues cause endothelium-dependent contractions that are mediated by prostaglandin endoperoxides and suggest that they have properties other than simple inhibition of NO synthesis in porcine coronary arteries.

Animals↗
PubMed1995

Tyrosine kinase inhibitor suppresses coronary arteriosclerotic changes and vasospastic responses induced by chronic treatment with interleukin-1 beta in pigs in vivo.

We recently demonstrated that chronic treatment with IL-1 beta induces coronary arteriosclerotic changes and vasospastic responses to autacoids in pigs in vivo and that those responses are importantly mediated by PDGF. The receptors for PDGF and other major growth factors are known to have tyrosine kinase activity. We therefore investigated the effects of a selective tyrosine kinase inhibitor, ST 638, on those responses induced by IL-1 beta in our swine model. Intimal thickening and coronary vasospastic responses to serotonin and histamine were induced at the site of the coronary artery where IL-1 beta was chronically and locally applied. These responses were significantly suppressed in a dose-dependent manner by cotreatment with ST 638. In addition, ST 494, which is an inactive form of ST 638, did not inhibit those responses. The treatment with ST 638 alone did not affect the coronary vasoconstricting responses to the autacoids. Immunoblotting using an antibody to phosphotyrosines confirmed the inhibitory effects of ST 638 on the tyrosine phosphorylations induced by IL-1 beta. These results thus suggest that tyrosine kinase activation may play an important role in mediating the effects of IL-1 beta, while also suggesting that ST 638 has an inhibitory effect on the arteriosclerotic changes and vasospastic responses to autacoids in our swine model in vivo.

Animals↗
PubMed1995

Prevalence of seasonal difficulties in mood and behavior among Japanese civil servants.

OBJECTIVE: Most prevalence studies of seasonal changes in mood and behavior have come from Western countries. The authors' goal was to determine the prevalence of seasonal changes in mood and behavior in a randomly selected group of Japanese workers. METHOD: They administered a Japanese translation of the Seasonal Pattern Assessment Questionnaire to 1,276 civil servants in Nagoya, Japan. RESULTS: The estimated prevalence of winter seasonal affective disorder was 0.86%, the estimated prevalence of winter subsyndromal seasonal affective disorder was 0.86%, the estimated prevalence of summer seasonal affective disorder was 0.94%, and the estimated prevalence of summer subsyndromal seasonal affective disorder was 2.12%. CONCLUSIONS: The authors conclude that seasonal changes in mood and behavior occur in Japan, but at a lower frequency and with a different profile than in the United States or Europe.

Adult↗
PubMed1995

Dietary high-linoleate safflower oil is not hypocholesterolemic in aged mice after a long-term feeding--comparison with lard, perilla oil and fish oil.

Aged mice (6 months of age) fed a conventional diet were shifted to diets containing 10% lard, high-linoleate safflower seed oil, high alpha-linolenate perilla seed oil or high-docosahexaenoate fish oil. A significant increase in whole body cholesterol (/g wt) was seen within 30 d after the shift (rapid response), followed by a gradual decrease in 60 to 120 d (slow response); similar changes occurred in all the dietary groups. Shortly after the shift, the serum cholesterol concentrations increased to higher levels in the lard and safflower oil groups than in the other groups, and the levels at 120 d were in the group order of safflower oil > lard > perilla oil > fish oil. Rapid and slow responses to dietary shifts were also seen in hepatic cholesterol levels (/g wt), which were higher in the lard group than in the other groups at 120 d. The arterial cholesterol contents of the fish oil group tended to be less than in the other groups at 120 d. Thus in aged mice after a relatively long-term feeding (> one tenth of the life-span), safflower oil was not hypocholesterolemic as compared with lard and other omega 3-rich oils. Long-term feeding of fish oil maintained serum cholesterol concentrations at lower levels than feeding with safflower oil or lard and without accumulating cholesterol in the aorta, liver or whole body; perilla oil was also hypocholesterolemic but to a lesser degree than fish oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1995

Rumen ciliates of Tokara native goat in Kagoshima, Japan.

The composition of rumen ciliate protozoa was surveyed in 15 Tokara native goats, Capra hircus domesticus, inhibiting Kagoshima, Japan. As a result, of 11 species with 3 forms under 5 genera detected, Entodinium simplex, E. nanellum and E. rectangulatum were found in all the animals examined. The large ophryoscolecid ciliates detected were Polyplastron multivesiculatum and Metadinium affine alone, which have been regarded as the typical members of Type A composition proposed by Eadie. Since Tokara native goats have been bred isolated in a small islet for a long time, native goats that had been kept in south Japan might possess Type A fauna. Average ciliate density was 43.9 x 10(4) per 1 ml of rumen fluid. The number of species per host was 8.3 on average. Diversity index was 1.412 on average.

Animals↗
PubMed1995

In vivo effect of cabergoline, a dopamine agonist, on estrogen-induced rat pituitary tumors.

Cabergoline (CG) is a dopamine agonist that inhibits the secretion of prolactin (PRL) and growth hormone. In the present study, we evaluated the in vivo effect of CG on PRL secretion and the pituitary tumor induced by estrogen. Estrogen was administered by subcutaneous injection to 4-week-old Fischer 344 rats weekly for 10 weeks to induce tumors. On the last day of estrogen administration, doses of either CG or bromocriptine (BC), 0.6 mg/kg, were administered as a single oral route or chronically, given every third day. Sera and pituitary tumors were sampled on each treatment schedule. Serum levels of PRL were measured and the pituitary glands were weighed. Immunohistological evaluation was performed by optical and electron microscopy. A single dose of CG significantly inhibited the serum levels of PRL for 6 days. Following a single dose of BC, the PRL level was significantly inhibited only at 6 hours' postadministration. The continued oral administration of CG significantly reduced both the serum PRL level and the weight of the pituitary during 15 to 60 days of treatment as compared with BC. Morphologic studies revealed that CG reduced the size of the cells and of the granules, and increased the number of granules per unit area of the cytoplasm. These findings suggest that CG inhibits the maturation of PRL secretory granules and the secretion of PRL more than its synthesis. Thus, CG induced a prolonged lowering of PRL and had a good antitumor effect on rat pituitary tumors induced by estrogen.

Animals↗
PubMed1995

Characteristics of prolactin secretion in normal and estrogen-treated pituitaries of rats at the single cell level: analysis by reverse hemolytic plaque assay.

We studied PRL release from individual pituitary cells in normal and estrogen (E2)-treated female Fischer 344 rats by means of a reverse hemolytic plaque assay. In this assay, the area of the hemolytic plaque around a pituitary cell is proportional to the amount of hormone secreted from the cell. Multimodal distribution of the plaque area was observed in normal pituitary cells, and was unchanged in the course of aging. In E2-treated pituitary cells, bimodal distribution was found. The heterogeneity of the distribution pattern (functional heterogeneity) and PRL secretion from a single pituitary cell decreased in association with the length of E2 treatment. The mean plaque area for the E2-treated pituitary cells was smaller than that for the normal pituitary cells. These results suggest that in E2-treated pituitary cells, the functional heterogeneity and PRL release from a single cell decrease as tumorigenesis progresses.

Animals↗
PubMed1995

Effect of cabergoline, a dopamine agonist, on estrogen-induced rat pituitary tumors: in vitro culture studies.

Cabergoline (CG) is a dopamine agonist that inhibits secretion of prolactin (PRL) and growth hormone. The purpose of this study was to investigate the PRL-lowering effect and antitumor effect of CG on estradiol-induced rat pituitary tumors in vitro and to elucidate these mechanisms. We compared the effects of CG with those of bromocriptine (BC) in terms of the inhibition of hormone secretion as well as antitumor effects on rat pituitary tumors. Primary cultures of dissociated pituitary tumor cells were used in these studies. A significant inhibition of prolactin (PRL) secretion was observed for both drugs within 12 h after treatment, and the inhibitory effects of CG and BC were antagonized by sulpiride or haloperidol. Inhibitory effect on PRL secretion after 12-h BC or CG pretreatment was more pronounced with CG than BC treatment at all time points. PRL secretion in group pretreated with CG was significantly suppressed at 72 h when compared to that of vehicle. Inhibition of de novo PRL synthesis was better demonstrated in the CG group. These findings suggest that CG has a higher affinity for the D2 receptor of pituitary cells as compared to BC and may preferentially inhibit PRL secretion rather than PRL production. An antitumor effect of CG has been confirmed at a lower dosage than that of BC.

Animals↗
PubMed1995

Em18, a new serodiagnostic marker for differentiation of active and inactive cases of alveolar hydatid disease.

We determined whether detection of antibody response against a newly detected epitope, designated Em18, among Echinococcus multilocularis antigens could be a reliable marker for differentiation of active cases of alveolar hydatid disease (AHD) from inactive cases. Fifteen Alaskan patients with either active or inactive lesions of AHD previously confirmed clinically, pathologically, and serologically by the Em2-enzyme-linked immunosorbent assay (ELISA) were used for a blind test by Western blotting. Ten and five cases were considered to be active and inactive cases, respectively. One of the 10 cases classified serologically as active was judged to be inactive based on clinical and pathologic criteria; the patient had a recognizable parasitic lesion, and following short-term treatment with albendazole, a biopsy of the liver showed a degenerated lesion that did not grow in rodents. The five cases judged to be inactive included two confirmed inactive cases with cicatrized lesions and three active cases that showed the weakest values in the Em2-ELISA. The most predominant IgG subclass responding to Em18 was IgG4. In general, there were good correlations between 1) the antibody response against Em18 and the presence of active lesions and 2) the antibody response against Em18 and the Em2-ELISA values.

Acute Disease↗
PubMed1995

[Clinical significance of proliferating cell nuclear antigen (PCNA) and argyrophilic nucleolar organizer region (AgNOR) in testicular tumors].

BACKGROUND: Proliferative potential of testicular tumor was assessed by immunohistochemistry using anti-proliferating cell nuclear antigen (PCNA) monoclonal antibody and silver staining of argyrophilic nucleolar organizer region (AgNOR), and the results were compared with clinical course. METHODS: Fourty-five patients with testicular tumor and 10 normal testicles were investigated. All specimens were fixed with 10% buffered formaliun within 24 hours. The interval between patient's recognition of testicular swelling for the first time and the date for operation was designated as M (months), and the specimen weight was designated as g (gram). Growth rate of the primary tumor was estimated roughly by g/M. RESULTS: PCNA positive rates in seminomas, non-seminomas and normal testes were 70.5 +/- 19.1% (mean +/- S.D.), 80.4 +/- 10.5% and 17.7 +/- 7.8%, respectively. PCNA positive rate in stage I seminoma (64.4 +/- 19.9%) was significantly lower than stage II and III seminoma (83.6 +/- 7.3%) (p < 0.05), but not significant between stage I non-seminoma and stage II, III non-seminoma. The mean numbers of AgNOR per nucleus in seminomas, non-seminomas and normal testes were 8.09 +/- 1.35 (mean +/- S.D.), 6.89 +/- 1.43, 4.18 +/- 1.60, respectively and significantly higher in testicular tumors than normal testes. There were, however, no significant difference between their clinical stages. Logarithmic significant correlation was observed between PCNA positive rate and the growth rate in primary lesion, but no correlation was found between mean number of AgNOR per nuclei and the growth rate. Of the 10 patients with stage I non-seminomas received surveillance policy, four relapsed. Of the 10 patients, 4 of the 6 patients with higher than 75% PCNA positive rate relapsed, whereas, none of the 4 patients with lower than 75% PCNA positive rate relapsed. There were no significant correlation between PCNA positive rate and number of AgNOR. CONCLUSION: PCNA is more accurate indicator of growth potential in testicular tumor than AgNOR and may predict recurrence in stage I non-seminomatous testicular tumor patients followed by surveillance policy.

Carcinoma, Embryonal↗
PubMed1995

A new antiherpetic agent produced by Streptomyces sp. strain no. 758.

A new antiherpetic agent, AH-758, was isolated from the culture broth of Streptomyces sp. strain No. 758. The structure was determined by NMR special analyses to be a new antibiotic belonging to bafilomycin group containing (5-oxo-2-pyrrolin-2-yl) methyl fumarate in its C-21.

Anti-Bacterial Agents↗