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Biomedical subjects

A Ito

Publications and source records attributed to A Ito.

At least 559 records · Page 31Linked to original sources

Localization of mRNA for c-kit receptor and its ligand in the brain of adult rats: an analysis using in situ hybridization histochemistry.

Localization of mRNA for the c-kit receptor and its ligand (Sl factor) in the brain of adult rats was studied using in situ hybridization histochemistry. The mRNA for the c-kit receptor was detected in the forebrain, the lower brain stem and the cerebellum. In the forebrain, the c-kit mRNA signals were detected in the olfactory bulb, the caudate-putamen, throughout the superficial cortex, the accumbens nucleus, the nucleus of vertical limb diagonal band, the bed nucleus of anterior commissure, Ammon's horn, the entopeduncular nucleus, the subthalamic nucleus, the dorsal raphe nucleus, the parasubiculum, the presubiculum, the ventricular nucleus of lateral lemniscus, and the entorhinal cortex. In the lower brain stem, the signals were detected in the inferior colliculus, the spinal vestibular nucleus, the spinal tract nucleus of trigeminal nerve, and the pyramidal tract. In the cerebellum, the signals were detected in the molecular layer of the cortex and cerebellar nuclei. By contrast, the signals of mRNA for Sl factor were detected in the forebrain and the cerebellum. In the forebrain, the signals were detected in the olfactory bulb, the endopiriform nucleus, the septohippocampal nucleus, the habenular nuclei, and most of the thalamic nuclei. In the cerebellum, the signals were detected in Purkinje cells. Several pairs of structures were found in which mRNA of either the c-kit receptor or the Sl factor was expressed and between which the synaptic connection had been reported, suggesting that the interaction between the c-kit receptor and the Sl factor may play some roles in the development of such synaptic connections.

Animals↗

Dual mode cytotoxicities of reactive oxygens on L5178Y radiosensitive mutant M10.

Cytotoxic effects of O2- and H2O2 on mammalian cells were investigated in comparison with the relative sensitivity of mouse L5178Y cells and its radiosensitive mutant M10. Both O2- and H2O2 exhibited two different modes of cytotoxic actions depending on their exposure rates: At a high exposure rate (4.3 nmol of O2-/mL/min), M10 was more sensitive to O2- than L5178Y normal type cell, in agreement with the case of X-rays; while at a low exposure rate (five times less than the high exposure rate), M10 became more resistant than L5178Y. Similar results were obtained with H2O2. Reactive species responsible for these two different cytotoxic actions were examined with special reference to the metal-catalyzed Haber-Weiss reaction, by using a metal chelator, 1,10-phenanthroline, and an .OH scavenger, dimethylsulfoxide (DMSO). Significant protection by 1,10-phenanthroline was observed, which indicates the presence of a metal-dependent process in both cytotoxic actions. DMSO showed a marked protective effect, except for the case of M10 exposed at the low exposure rate, in which DMSO showed no protection. The resistance of M10 to O2- and H2O2 observed at the low exposure rate suggests the possibility that reactive species other than .OH are involved in the cytotoxicity.

Animals↗

Chemotactic factor in the pregnant rabbit uterine cervix.

OBJECTIVE: Neutrophil accumulation is one of the characteristic changes observed in uterine cervical stroma at term pregnancy, but chemotactic activity in the tissue is obscure. Our study examined the existence and production of chemotactic factor in the rabbit uterine cervix. STUDY DESIGN: Uterine cervical explants of rabbits at term pregnancy and nonpregnant rabbits were cultured with and without interleukin-1 alpha. Rat neutrophilic chemotaxis in culture media was evaluated with a Boyden chamber. RESULTS: Tissue extract from the pregnant rabbit uterine cervix at term pregnancy contained more chemoattractive activity than the nonpregnant cervix. Production of chemoattractant from cultured rabbit cervical explants at term pregnancy was also higher than that from nonpregnant explants. The addition of interleukin-1 alpha to the culture system promoted its production. This chemoattractant was characterized as a true chemotactic factor and heat-stable and trypsin-sensitive protein with an apparent relative molecular mass of 16,200. So far, these properties are very similar to those of the interleukin-8 family. Rabbit uterine cervical fibroblast is characterized as a chemotactic factor-producing cell in the rabbit uterine cervix. CONCLUSION: These results indicate that interleukin-8-like chemotactic factor participates in the cervical ripening at term pregnancy and that the production of this factor is controlled effectively by interleukin-1.

Animals↗

Macrophages in protective immunity to Hymenolepis nana in mice.

When mice were treated with carrageenan just before infection with eggs of Hymenolepis nana, they failed to exhibit sterile immunity to the egg challenge, with evidence of a decrease in the number of peripheral macrophages (Mø) and the rate of carbon clearance. Although there were high levels of interleukin-1 (IL-1) released into the intestinal tracts of the parasitized mice at challenge infection, there was almost no release of IL-1 in those treated with carrageenan just before challenge. These results strongly suggest that Mø have an important role in protective immunity to H. nana in mice.

Animals↗

Increase in estrogen receptor levels in MNU-induced thyroid tumors in LE rats.

Estrogen receptor (ER) levels were evaluated in thyroid tumors induced by N-methyl-N-nitrosourea (MNU) and low iodine diet (LID) or propylthiouracil (PTU) in intact and estrogen (E2) loaded Long-Evans (LE) rats. MNU at 40 mg/kg body wt was injected in 50 day-old LE rats of both sexes. The animals were killed 17-22 weeks later and the thyroid tissues were subjected to ER assay. In LID-treated groups, cytosolic ER (cER) levels were 6.7 +/- 5.8 (fmol/mg protein, mean +/- SE) in females and 0.7 +/- 1.4 in males, E2 increased the ER levels. In E2-loaded LID groups, cER levels were 12.9 +/- 3.7 in females and 1.7 +/- 1.7 in males. PTU treatment produced almost comparable ER levels as LID treatment. PTU treatment as well as LID treatment increased the serum TSH levels with E2 treatment producing additional elevation. In evaluating ER levels by histological type of thyroid tumors, the level in cER plus nER showed the lowest value of 6 +/- 6.4 (fmol/mg DNA, mean +/- SE) in hyperplasia, followed by 129 +/- 52.3 in adenoma and 289 +/- 51.7 in carcinoma. The rates of BrdU incorporation in thyroid follicles indicated higher proliferation activity in the area of adenoma and carcinoma rather than in the hyperplastic area. These data suggested that E2 treatment increases the ER levels in MNU and LID/PTU-induced thyroid tumors. The level of ER was correlated to the histological type of thyroid tumors.

Adenoma↗

Mitochondrial targeting signal of rat liver monoamine oxidase B is located at its carboxy terminus.

Monoamine oxidase B, a typical intrinsic protein of the outer mitochondrial membrane, has an uncleavable targeting signal and is inserted into the membrane without proteolytic maturation. To investigate the region responsible for targeting the enzyme to the outer mitochondrial membrane, various mutated proteins were expressed in cultured mammalian cells, and the distributions of the expressed proteins were analyzed by immunofluorescence microscopy and subcellular fractionation. Deletion of the carboxy-terminal 28 amino acids of monoamine oxidase B abolished the transfer of the enzyme to mitochondria, while the deletion of the amino-terminal 55 amino acids had no effect on the transfer to mitochondria. The existence of the targeting signal at the carboxy-terminal portion of the enzyme was confirmed by using hybrid proteins in which the amino- or carboxy-terminal portion of the enzyme was fused to the hydrophilic portion of cytochrome b5. The fused protein with the carboxy-terminal 29 amino acid residues of monoamine oxidase B was localized in mitochondria, whereas that with 10 amino acids remained in the cytoplasm. These results indicate that the targeting signal of monoamine oxidase B is present within its carboxy-terminal 29 amino acid residues.

Animals↗

Tumor necrosis factor-alpha stimulates the biosynthesis of matrix metalloproteinases and plasminogen activator in cultured human chorionic cells.

To investigate the role of tumor necrosis factor-alpha (TNF alpha) in advanced collagenolysis and degradation of connective tissue components in preterm parturition, the effects of human recombinant TNF alpha (hrTNF alpha) on the production of matrix metalloproteinase 1 (MMP-1)/tissue collagenase, MMP-3/stromelysin, tissue inhibitor of metalloproteinases (TIMP), urokinase type-plasminogen activator (uPa) and prostaglandin (PG) E2 in human chorionic cells were examined in vitro. Human chorionic cells, but not amniotic cells, were found to respond to macrophage-conditioned medium (contains mainly interleukin 1) to produce MMP-1 and MMP-3. This indicated that the chorionic cell is one of the MMP-producing cells of fetal membranes. When confluent chorionic cells were treated with hrTNF alpha, the production of MMP-1 and MMP-3 as well as of uPa and PGE2 was greatly increased in a dose-dependent manner. In contrast, the production of TIMP was suppressed by hrTNF alpha. These results suggested that TNF alpha may participate in destruction of collagen and other connective tissue matrix components of fetal membranes and in promotion of uterine contractility in preterm parturition with intraamniotic infection.

Amnion↗

Effects of sodium chloride and ethanol on stomach tumorigenesis in ACI rats treated with N-methyl-N'-nitro-N-nitrosoguanidine: a quantitative morphometric approach.

Effects of sodium chloride (NaCl) and ethanol on gastric tumor development in rats after treatment with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were studied. MNNG, dissolved in distilled water (5 g/liter), was administered orally once by gastric tube at a dose of 0.25 ml/10 g body weight to 4-week-old ACI rats. After this carcinogen initiation, animals were fed on a diet containing 10% NaCl (Group 2) or normal diet with 10% ethanol in the drinking water (Group 4). MNNG alone (Group 1), NaCl alone (Group 3), ethanol alone (Group 5), and control (Group 6) animals were also maintained. All survivors were killed one year after the MNNG application. Incidences of tumors in the forestomach and glandular stomach were significantly increased in Group 2 as compared to Group 1 (P less than 0.05). The height of the pyloric mucosa was significantly greater in Group 2 than in Groups 4, 5 or 6 (P less than 0.05). In the fundic area, the mucosal height was significantly decreased in Group 4 as compared to Group 6 (P less than 0.05). The present results demonstrate that whereas tumors in the glandular stomach and forestomach are both promoted by NaCl, ethanol is without influence. Furthermore, NaCl, a promoter of glandular stomach tumorigenesis also increases cell proliferation.

Animals↗

Carcinogenicity of 1,2-dimethylhydrazine in colorectal tissue heterotopically transplanted into the glandular stomach of rats.

The present study was designed to examine the effect of the intestinal carcinogen 1,2-dimethylhydrazine (DMH) on grafted colorectal mucosa implanted into the glandular stomach of rats. Four groups were studied: Group 1 received the operation and DMH, Group 2 received the operation alone, Group 3 received DMH alone and Group 4 (controls) received only a sham operation. For Groups 1 and 2, about 8-mm diameter segments of colorectal tissue obtained from various sites in the large intestine of 8-week-old male F344 rats were isologously implanted into the fundic region of the stomachs of age-matched rats. DMH was injected at a dose of 20 mg/kg body weight i.m. per week for 20 weeks beginning 4 weeks after the operation. The animals were then observed for 8 months after the initial DMH treatment. In Group 1, adenocarcinomas developed in 41 of 60 successful implants (68%). Furthermore, poorly differentiated type tumors were observed in the grafts obtained from the rectum. This finding was contrary to that for intrinsic rectal tumors, all of which were well differentiated. The histochemical staining of mucin in the tissues from different sites of the large intestine revealed that sulfomucin, which normally exists essentially only in the intrinsic descending colon or rectum, was present in the grafts from the proximal ascending or ascending colon. No gastric tumors were observed in the control rats, which received either DMH or sham operations alone. Tumors in the intrinsic large intestine were observed only in rats that received DMH. These results indicate that colorectal mucosa implanted into the glandular stomach, like the intrinsic large intestine, is still sensitive to tumorigenesis caused by DMH.

1,2-Dimethylhydrazine↗

Significance of strain and sex differences in the development of 252Cf neutron-induced liver tumors in mice.

Mouse liver tumors occurring in C3H/HeN, C57BL/6N and C3B6F1 hybrid (C3H x C57BL) were studied following 252Cf fission neutron irradiation. Three strains of mice of both sexes (about 30 mice/group) were irradiated once with 252Cf at doses of 0, 12.5, 50 and 200 cGy. The groups were observed for 13 months after irradiation. The incidence of liver tumors in the non-irradiated controls was 0% in both sexes of C57BL/6N, 11.7% in males and 0% in females of C3B6F1 and 39.5% in males and 11.4% in females of C3H/HeN mice. In the four strains of mice thus far studied, including B6C3F1 hybrid (C57BL x C3H) which was previously studied, 252Cf irradiation has increased the tumor incidence dose-dependently in males and in females, but less effectively in females. The mean number and size of liver tumors were clearly correlated with tumor incidence. The incidence was always highest in C3H/HeN mice of both sexes, followed by B6C3F1, C3B6F1 and C57BL/6N mice. The influence of sex hormones was studied in B6C3F1 mice of both sexes after 200 cGy of 252Cf irradiation. In males, the incidence of liver tumors was significantly decreased from 55.2% to 23.3% and 25.9% after orchidectomy, and in females it was slightly decreased from 27.6% to 14.8% and 18.8% after ovariectomy. Supplementation of testosterone in orchidectomized mice did not restore the occurrence of liver tumors.

Animals↗

The effects of sodium chloride, miso or ethanol on development of intestinal metaplasia after X-irradiation of the rat glandular stomach.

The influence of sodium chloride (NaCl), miso (Japanese soybean paste) and ethanol on development of intestinal metaplasia was examined. Five-week-old male CD(SD): Crj rats were treated with two 10 Gy doses of X-rays to the gastric region at a 3-day interval (total 20 Gy). After irradiation, the rats received supplementation with NaCl (1% or 10% in diet), miso (10% in diet) or ethanol (10% in drinking water) for 12 months. The number of alkaline phosphatase-positive foci of intestinal metaplasia in rats given 1% NaCl diet (Group 3) after X-rays was significantly elevated as compared to that in rats given X-rays alone (Group 1) (P < 0.01) or X-rays with 10% NaCl (Group 2) (P < 0.01). In the pyloric gland mucosae, the total numbers of metaplastic foci in rats of Group 3 were much higher than in Group 2, or after miso diet (Group 4) or ethanol supplementation (Group 5) (P < 0.01), but no difference was found between Group 2, 4 or 5 and Group 1. Atypical hyperplasia only appeared at incidences of less than 6% in Groups 1-3 and no promoting effect on gastric tumorigenesis was evident in Group 2. The present results thus showed that the occurrence of intestinal metaplasia induced by X-irradiation can be significantly increased by administration of 1% NaCl and decreased by 10% NaCl and ethanol, but this is not associated with any influence on gastric neoplasia.

Alkaline Phosphatase↗

Distinct cellular expression of calcineurin A alpha and A beta in rat brain.

Specific polyclonal antibodies that distinguish the two distinct isoforms of the catalytic subunit of calmodulin-dependent protein phosphatase, calcineurin A alpha and A beta, were prepared, and the distribution of calcineurin A alpha and A beta in rat brain was studied using immunochemical and immunocytochemical techniques. Immunochemical measurement revealed that the regional distributions of the two isoforms differed and that A alpha was more abundant than A beta in the rat brain. The subcellular distribution patterns of both isoforms were similar. Both isoforms were highly enriched in cytosolic fractions, including the synaptosomal cytosol. Immunocytochemical analysis revealed that both A alpha and A beta immunoreactivities differed in regional and cellular localizations. These different patterns of expression suggest that the two isoforms of calcineurin A may each have specific functions in modulating neuronal activity in particular cell types.

Animals↗

Phosphate taxis in Pseudomonas aeruginosa.

Pseudomonas aeruginosa was shown to be attracted to phosphate. The chemotactic response was induced by phosphate starvation. The specificity of chemoreceptors for phosphate was high so that no other tested phosphorus compounds elicited a chemotactic response as strong as that elicited by phosphate. Competition experiments showed that the chemoreceptors for phosphate appeared to be different from those for the common amino acids. Mutants constitutive for alkaline phosphatase showed the chemotactic response to phosphate regardless of whether the cells were starved for phosphate.

Alkaline Phosphatase↗

Establishment of a folliculo-stellate-like cell line from a murine thyrotropic pituitary tumor.

An isologously transplantable mouse thyrotropic pituitary tumor (TtTb) that had been induced by radiothyroidectomy was found to form lobules composed of parenchymal glandular cell elements. The surfaces of these lobules were covered by stellate cells bearing long processes that gave a strong immunopositive reaction with a specific antiserum against glial fibrillary acidic protein (GFAP). GFAP was also positive in pituitary folliculo-stellate cells (FS cells). Since in the anterior pituitary gland, no other cellular component showing positive staining with anti-GFAP antibody was observed, it seems probable that the GFAP-positive cells in the thyrotropic tumor are related to the FS cells in the anterior pituitary. Upon cultivation of the thyrotropic tumor, cells with long processes appeared. These cells showed strong staining for GFAP and were dependent on basic fibroblast growth factor for cell growth. By repeated passage, the GFAP-positive cells became a stably growing immortal cell line, which was tentatively named TtT/GF. Since the characteristics of TtT/GF were similar to those of FS cells in the anterior pituitary, i.e. the presence of many lysosomes and numerous intermediate filaments in the cytoplasm, phagocytic activity, follicle formation, and GFAP and S-100 protein positivity, we suggest that TtT/GF cells are derived from pituitary FS cells.

Animals↗

Image blurring by thermal diffusion in the observation of hydrated biomolecules with soft X-ray microscopy.

A simple model is presented for the estimation of image blurring in X-ray microscopy of biological specimens in a hydrated environment. The model is essentially based on thermal diffusion of an object to be imaged. The degree of image blurring by diffusion depends on the following situations of the object. The object is free from, is tightly fixed to, or is partially connected to the surrounding structures. The proper imaging time required to achieve a given resolution in X-ray microscopy of biological structures was estimated with the present method. The results suggest that imaging time shorter than 3 msec (free) to 1.4 sec (tightly fixed) is required for the observation of a cell (30 microns in diameter) at the resolution of 100 nm. The model is also applicable to a fragmented object caused by imaging X-rays.

Cell Nucleus↗

[The effect of stationary time of punch in the process of compression on dividing properties of scored tablets].

The significance of the stationary time of punch in the process of compression on the dividing properties of scored tablets was investigated in several tablets prepared from lactose, corn starch, hydroxypropyl starch, synthetic aluminum silicate, microcrystalline cellulose or Perfiller. The dividing strength of scored tablets was not affected by the stationary time of punch. The effect of the stationary time of punch on the coefficient of variation of divided tablet weight differed in the compacting characteristics and compaction profiles of powders. In case of tablets prepared from microcrystalline cellulose, the effect of stationary time of punch was not observed. However, in the other excipients, there existed a specific stationary time of punch to minimize the coefficient of variation of divided tablet weight. The time was different due to the change of compression pressure. The coefficient of variation of divided tablet weight showed minimum at the longer stationary time of punch when tablets were compressed at the low compression pressure, and the time showed a tendency to become short with the increase of compression pressure. These results suggested that the effect of the stationary time of punch on the coefficient of variation of divided tablet weight was concerned with the compaction structure of powders produced by the movement of punch in the process of compression.

Pressure↗