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Biomedical subjects

M Baba

Publications and source records attributed to M Baba.

At least 631 records · Page 35Linked to original sources
PubMed1989

Promotion by bombesin of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effects of bombesin on the incidence, number, histological type, and depth of involvement of gastric cancers induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were investigated in male Wistar rats. Rats received alternate-day s.c. administration of 20 or 40 micrograms/kg body weight of bombesin in depot form after p.o. treatment with the carcinogen for 25 weeks. Prolonged administration of bombesin at 40 micrograms/kg led to a significant increase in the incidence and number per rat of gastric cancers of the glandular stomach at Week 52. In rats that had received alternate-day injections of 20 micrograms/kg of bombesin, the number of gastric cancers per rat, but not the incidence of cancer, was significantly more than in untreated rats. However, bombesin at both dosages did not affect the histological appearance of the lesions or their depth of involvement. At Weeks 30 and 52, norepinephrine concentrations in the fundic and antral portion of the gastric walls and labeling indices in the antral and fundic mucosae were significantly higher in rats treated with bombesin at both dosages than in untreated rats. These findings indicate that bombesin enhances gastric carcinogenesis after administration of N-methyl-N'-nitro-N-nitrosoguanidine is stopped and that this effect may be related to its effects in increasing tissue norepinephrine concentrations in the stomach wall and increasing cell proliferation in the gastric mucosa.

Animals↗
PubMed1989

Inhibition by cysteamine of hepatocarcinogenesis induced by N-nitrosomorpholine in Sprague-Dawley rats.

The effect of cysteamine (2-aminoethanethiol hydrochloride) on hepatocarcinogenesis induced by N-nitrosomorpholine (NNM) was investigated in male Sprague-Dawley rats. Rats received alternate-day s.c. injections of cysteamine, and beginning in experimental week 3 were given drinking water containing NNM for 8 weeks. Pre-neoplastic and neoplastic lesions staining positive for gamma-glutamyl transpeptidase (GGT) or glucose-6-phosphate dehydrogenase (G6PD) were examined by histochemical techniques. In week 18, quantitative histological analysis showed that prolonged administration of cysteamine resulted in a significant reduction in the number of GGT-positive and G6PD-positive hepatic lesions. Histologically, hepatocellular carcinomas were significantly fewer and smaller in GGT-positive and G6PD-positive lesions in rats treated with cysteamine than in untreated rats. Administration of cysteamine also caused a significant decrease in the liver norepinephrine concentration and in the labelling indices of pre-neoplastic lesions and the surrounding liver. Our findings indicate that cysteamine inhibits hepatocarcinogenesis; this may be related to its reducing effect on norepinephrine concentration in the liver and its subsequent inhibition of cell proliferation in neoplastic lesions and surrounding hepatocytes.

Animals↗
PubMed1989

Effect of 6-hydroxydopamine on gastric carcinogenesis and tetragastrin inhibition of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effects of 6-hydroxydopamine (6-OHDA) on gastric carcinogenesis, on inhibition by tetragastrin of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine, and on the tissue catecholamine concentrations of the gastric wall and the labeling index of the gastric mucosa were investigated in inbred Wistar rats. Rats received s.c. injections of tetragastrin (1 mg/kg of body weight every other day) in depot form, i.p. injections of 6-OHDA (42 mg/kg twice within 24 h and 105 mg/kg every 2 wk), or injections of both compounds after 25 wk of p.o. treatment with N-methyl-N'-nitro-N-nitrosoguanidine (100 micrograms/ml). At Wk 52, prolonged administration of tetragastrin or 6-OHDA had significantly reduced the incidence and the number of adenocarcinomas. Combined administration of tetragastrin and 6-OHDA significantly enhanced the inhibitory effects of tetragastrin or 6-OHDA on gastric carcinogenesis. Administration of 6-OHDA but not tetragastrin, caused a significant decrease in norepinephrine concentrations in the antral portion of the gastric wall. Rats treated with tetragastrin or 6-OHDA had a significantly lower labelling index of the antral mucosa, and this index was significantly decreased by combined administration of tetragastrin and 6-OHDA, as compared with labeling indices observed after treatment with tetragastrin or 6-OHDA alone. These findings indicate that 6-OHDA exerts a protective effect against gastric carcinogenesis and enhances the inhibitory effect of tetragastrin on gastric carcinogenesis. This effect of 6-OHDA may be related to its ability to inhibit cell proliferation of the antral mucosa.

Animals↗
PubMed1989

Role of glucose-6-phosphate dehydrogenase on enhanced proliferation of pre-neoplastic and neoplastic cells in rat liver induced by N-nitrosomorpholine.

The relationship between G6PD and the number and size of pre-neoplastic and neoplastic lesions in rat liver was examined. Male Sprague-Dawley rats were given drinking water containing 250 mg/l of NNM for 8 weeks. Pre-neoplastic and neoplastic lesions with positive staining of GT were classified histochemically into G6PD-positive and G6PD-negative lesions. At week 24, quantitative analysis showed that the incidence and number of G6PD-positive lesions were significantly higher than those of G6PD-negative lesions. Histologically, hepatocellular carcinomas were more frequent and larger in G6PD-positive lesions than in G6PD-negative ones. Statistical analysis of the quantitative data also showed that the number and volume of G6PD-positive hepatocellular carcinomas were significantly higher than in G6PD-negative carcinomas. The G6PD-positive pre-neoplastic lesions had a significantly higher labelling index than G6PD-negative ones. These findings revealed a considerable difference in the growth of these 2 populations of the lesions, and indicate that G6PD activity may be closely related to proliferation of the pre-neoplastic and neoplastic cells in the liver.

Animals↗
PubMed1989

Effects of propranolol and cimetidine on cysteamine inhibition of gastric carcinogenesis induced in Wistar rats by N-methyl-N'-nitro-N-nitrosoguanidine.

The effects of propranolol and cimetidine on inhibition by cysteamine (2-aminoethanethiol hydrochloride) of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and on gastric acid secretion, serum gastrin level, and labelling index of the gastric mucosa were investigated in inbred Wistar rats. Rats received alternate-day injections of cysteamine (25 mg/kg body weight) with or without propranolol (dl-propranolol hydrochloride) (2 mg/kg bw) or cimetidine (50 mg/kg bw) in depot form after 25 weeks of oral treatment with MNNG. Prolonged administration of cysteamine significantly reduced the incidence of adenocarcinoma of the glandular stomach. A combination of cysteamine and propranolol significantly accelerated the inhibitory effect of cysteamine on gastric carcinogenesis. However, with concomitant administration of cysteamine and cimetidine, the incidence of adenocarcinoma was slightly but not significantly increased as compared to that after treatment with cysteamine alone. Administration of cysteamine caused a significant increase in gastric acid secretion and serum gastrin level, and a significant decrease in the labelling index of the antral mucosa. A combination of cysteamine and propranolol significantly increased gastric acid secretion by cysteamine alone and significantly decreased the labelling index of the antral mucosa. With this treatment, the serum gastrin level was significantly higher than the basal level, but the stimulated serum gastrin level was significantly lower than observed that after administration of cysteamine alone. In contrast, concomitant administration of cysteamine and cimetidine caused a significant decrease in gastric acid secretion and significant increase in the serum gastrin level as compared to the levels seen after treatment with cysteamine alone, but had no influence on the labelling index of the antral mucosa. These findings indicate that hypersecretion of acid, but not hypergastrinemia associated with hyposecretion of acid or achlorhydria, exerts a protective effect against gastric carcinogenesis, and that this effect may be related to its activity in decreasing proliferation of the antral mucosa.

Adenocarcinoma↗
PubMed1989

Enhancement of experimental gastric carcinogenesis induced in spontaneously hypertensive rats by N-methyl-N'-nitro-N-nitrosoguanidine.

The incidence, number, and histological types of gastric cancers induced by N-methyl-N'-nitro-N-nitrosoguanidine and the tissue norepinephrine concentration of the gastric wall were investigated in spontaneously hypertensive rats and in control Wistar Kyoto rats and Wistar rats. All rats were given drinking water containing 25 micrograms/ml of N-methyl-N'-nitro-N-nitrosoguanidine for 25 weeks. During Week 52, the incidence and number per rat of gastric cancers were significantly greater in spontaneously hypertensive rats than in Wistar Kyoto and Wistar rats. All tumors induced in the glandular stomach were adenocarcinomas, but no significant difference was found in the histological types of adenocarcinoma in the three strains of rats. At Weeks 15, 30, and 52, norepinephrine concentrations in the fundic and antral portion of the gastric walls and labeling indices in the antral and fundic mucosa were significantly higher in spontaneously hypertensive rats than in Wistar Kyoto and/or Wistar rats. These findings indicate that increased sympathetic nervous system activity enhances the development of gastric cancers, but immunological dysfunction in spontaneously hypertensive rats may contribute to the increased susceptibility to gastric cancer.

Adenocarcinoma↗
PubMed1989

Promotion by neurotensin of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effects of neurotensin on the incidence and histology of gastric cancers induced by N-methyl-N'-nitro-N-nitrosoguanidine were investigated in Wistar rats. Rats were given 100 or 200 micrograms per kg of body weight of neurotensin s.c. every other day in depot form after 25 wk of p.o. treatment with the carcinogen. Prolonged alternate-day administration of neurotensin at 200 micrograms per kg of body weight resulted in a significant increase in the incidence of gastric cancers of the glandular stomach by Wk 52. However, it did not influence the histological appearance of the gastric cancers. Furthermore, it caused a significant increase in the labeling indices of the epithelial cells of the antrum and of gastric cancers. In contrast, the administration of neurotensin at 100 micrograms per kg of body weight had a slight, but not significant, influence on the development of gastric cancers. These findings indicate that neurotensin promotes gastric carcinogenesis, and that this effect may be related to its effect in increasing proliferation of epithelial cells in the antral mucosa and in gastric cancers.

Animals↗
PubMed1989

Tumor necrosis factor enhances replication of human immunodeficiency virus (HIV) in vitro.

The effect of tumor necrosis factor (TNF) on the replication of human immunodeficiency virus type 1 (HIV-1) was investigated in several T4 lymphocyte cell lines. TNF markedly enhanced the cytopathogenicity of HIV-1, virion-associated reverse transcriptase (RT) activity in the cell culture supernatant, and viral antigen expression in MOLT-4 cells as early as 3 days after HIV-1 infection. A slight increase in RT activity was also observed in the supernatant of H9 cell cultures exposed to TNF. However, TNF did not increase either RT activity in MT-4 cell supernatants or viral antigen expression in HUT-78 cells. Thus, TNF is able to stimulate the replication of HIV-1 in de novo infected T4 cells although not all T4 cells seem to be sensitive to this stimulatory effect.

Antigens, Viral↗
PubMed1989

Serial section reconstruction using a computer graphics system: applications to intracellular structures in yeast cells and to the periodontal structure of dogs' teeth.

A computer graphics system for reconstruction from serial section micrographs was applied to intracellular details of a yeast target cell (Saccharomyces cerevisiae cell) induced by the alpha factor mating pheromone and was also applied to a periodontal structure of a dog tooth moved orthodontically. In the former, intracellular organelles and a distribution of vesicles could be clearly observed through the cell membrane using the transparent display method in which the smoothing of the reconstructed outer cell membrane surface by computer processing was applied to the transparent display. In the latter case, by cutting through a reconstructed dog tooth and its periodontal tissues, labiolingual and mesiodistal cut surfaces of the tooth and of adjacent alveolar bone could be observed with fine details (232 sections were used).

Animals↗
PubMed1989

Diagnosis of gastric cancers with fluorescein-labeled monoclonal antibodies to carcinoembryonic antigen.

Forty gastric adenocarcinomas in 30 resected stomachs were examined by an endoscopic immunofluorescent technique using fluorescein isothiocyanate (FITC)-labeled antibodies to carcinoembryonic antigen (CEA). Fluorescence images of the tumors were obtained with a newly developed endoscopic television system for detecting faint fluorescence. Computer-assisted processing was used to enhance the detection and localization of the tumors visualized by the immunofluorescent technique. Twenty seven (90%) of 30 tumors showed positive fluorescence after treatment with FITC-labeled antibodies for 60 minutes, whereas only two (40%) of five cancers could be detected by the immunofluorescent technique after treatment with antibodies for less than 60 minutes. There was no significant relationship between positive fluorescence and the gross and histological types or the stages of the tumors. In contrast, no positive fluorescence could be demonstrated in cases of benign gastric lesions or after pretreatment with FITC-labeled alpha-fetoprotein. This study therefore suggests that the immunofluorescent technique using FITC-labeled anti-CEA antibodies can be useful in detecting the early stages of gastric cancer.

Adenocarcinoma↗
PubMed1989

A clinical analysis of 32 brainstem haemorrhages; with special reference to surviving but severely disabled cases.

Thirty-two patients with CT-documented primary brainstem haemorrhage were reviewed retrospectively to obtain a clearer overall clinical picture, especially of the severely disabled survivors. They were divided into 3 groups according to outcome: eleven cases (Group 1) died within 1 month following haemorrhage, 11 cases (Group 2) survived but became bedridden, necessitating full living support, and 10 cases (Group 3) showed minimal neurological deficits and resumed normal activities. Owing to CT and improved critical care, the survival rate was 66% for the whole series. Group 2 comprised 34% of all cases. These patients were mostly alert, quadruplegic, and communicated only with great difficulty. The most common initial symptoms and CT finding in each group were as follows; Group 1: unconsciousness, respiratory disturbance, negative light reflex, tachycardia, and haematoma greater than 3.0 cm; Group 2: disturbance of consciousness, respiratory disturbance, positive light reflex, normal heart rate, and 2.0 greater than haematoma less than 3.5 cm; and Group 3: alertness or only slight disturbance of consciousness, normal respiration, positive light reflex, normal heart rate, haematoma less than 2.5 cm. Although there is an overlap among them, these findings will be useful to distinguish the three groups from each other. Patients with disturbance of consciousness, respiratory disturbance, positive light reflex, normal heart rate, and 2.0 greater than haematoma less than 3.5 cm, have a chance to survive, but in severely disabled condition, if they were treated with vigorous intensive care in the acute stage.

Adult↗
PubMed1989

In vitro activity of mannan sulfate, a novel sulfated polysaccharide, against human immunodeficiency virus type 1 and other enveloped viruses.

Mannan sulfate, a novel sulfated polysaccharide, was prepared and investigated for its activity against human immunodeficiency virus type 1 (HIV-1) in vitro. Mannan sulfate completely inhibited HIV-1-induced cell destruction and viral antigen expression in HIV-1-infected Molt-4 (clone 8) cells at a concentration of 4 micrograms/ml. The 50% antiviral effective doses obtained with mannan sulfate in Molt-4 (clone 8) cells and in MT-4 cells were 1.5 and 9.3 micrograms/ml, respectively. No toxicity for Molt-4 (clone 8) cells or MT-4 cells was observed at a concentration of 4,000 and 2,500 micrograms/ml, respectively. Mannan sulfate was also inhibitory to other enveloped viruses, i.e. herpes simplex virus types 1 and 2, vaccinia virus and vesicular stomatitis virus. These results suggest that mannan sulfate may be useful for the chemotherapy of various viral infections, including those causing and associated with AIDS.

HIV-1↗
PubMed1989

A new microcatheter system for endovascular treatment of cerebral arteriovenous malformations.

A new microcatheter system was used for diagnostic and therapeutic purposes in three cases of arteriovenous malformation. This microcatheter is used with a steerable guidewire and provides high selectivity of the target vessels and greater catheter maneuverability than does balloon catheters. Tissue adhesive was safely injected for the therapeutic embolization in two of the cases. With this system, however, the utmost attention is necessary to prevent reflux of the tissue adhesive and to avoid lacerating the feeding vessels with the guidewire. This microcatheter system was found to be very useful for diagnostic and therapeutic procedures in endovascular treatment of cerebral arteriovenous malformations.

Adult↗
PubMed1989

Allergen-specific induction of interleukin-2 (IL-2) responsiveness in lymphocytes from children with asthma. II. Regulation of IL-2 responsiveness by supernatants of normal lymphocytes.

Induction of interleukin-2 (IL-2) responsiveness by Dermatophagoides farinae (Df)-stimulated lymphocytes from children with asthma was markedly suppressed after the addition of culture supernatants from Df-stimulated normal T cells. Ovalbumin (OVA)-induced IL-2 responsiveness of lymphocytes from patients with hen-egg allergy was not suppressed by the supernatant from Df-stimulated T cells, indicating the antigenic specificity of the effect. Patients' lymphocytes whose IL-2 responsiveness was decreased still expressed Tac antigen (low-affinity IL-2 receptors) but, in contrast to the patients' original lymphocytes, did not absorb or respond to IL-2, suggesting the loss of high-affinity IL-2 receptors (p55/p75) from these cells. The supernatant from Df-stimulated normal T cells from one individual did not necessarily suppress the response of all patients tested, indicating the existence of some allogeneic barrier between the factor(s) and patients' lymphocytes.

Absorption↗
PubMed1989

Tetrazolium-based plaque assay for HIV-1 and HIV-2, and its use in the evaluation of antiviral compounds.

A modification of the MT-4 cell plaque assay for human immunodeficiency virus (HIV) is described, which gave reproducible results with all 4 HIV-1 strains and the two HIV-2 strains that were used. The main feature of this new method is the use of a tetrazolium (MTT) staining procedure. The number of plaques read after 4-6 days was essentially the same as the number of infectious units derived from the 50% cell culture infective dose (CCID50) in MT-4 suspension cultures. For a selected group of antiviral compounds the 50% plaque-inhibitory doses were comparable with the 50% inhibitory doses (ID50) in suspension cultures. In the plaque assay HIV-1 (HTLV-IIIB) and HIV-2 (LAV-2ROD) were equally susceptible to azidothymidine (AZT), and the same was true for didehydrodideoxythymidine (D4T). For these compounds it was irrelevant whether they were already present during the initial HIV adsorption phase or added immediately thereafter. Pentosan polysulfate proved about 20-fold more inhibitory to HIV-2 than HIV-1. There was a 5-fold increase in activity if present during the virus adsorption stage.

Antiviral Agents↗
PubMed1989

Protective effect of oral cysteamine against induction of gastric cancer by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effect of oral administration of cysteamine (2-aminoethanethiol hydrochloride) on the incidence and histology of gastric adenocarcinomas induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was investigated in inbred Wistar rats. Oral administration of 0.4% cysteamine in food after treatment with MNNG for 25 weeks significantly reduced the incidence and number of adenocarcinomas of the glandular stomach in experimental Week 52. Histological examination showed that adenocarcinomas that did develop in rats fed on cysteamine had high mucin-producing activity. Furthermore, oral administration of cysteamine caused a significant increase in serum gastrin level and significant decreases in the antral mucosal pH and the labeling indices of the antral mucosa. These findings indicate that cysteamine inhibits the development of gastric adenocarcinomas when given orally. This effect may be related to its ability to decrease proliferation of antral mucosal cells.

Adenocarcinoma↗