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Y Kameyama

Publications and source records attributed to Y Kameyama.

At least 19 recordsLinked to original sources
PubMed1992

Properties of plasma membrane-induced amylase release from rat parotid secretory granules: effects of Ca2+ and Mg-ATP.

A secretory granular fraction (SG) and a plasma membrane rich fraction (PM) have been isolated from rat parotid gland by differential and Percoll gradient centrifugation. With these two fractions, a cell-free interaction system has been reconstituted to clarify the exocytotic interaction between the secretory granules and plasma membranes, and the conditions of amylase release from SG have been characterized in vitro. The addition of PM into this assay system induced a rapid and transient release of amylase from SG. Some other membranes such as erythrocyte ghosts also mimicked the effect of PM. This release was increased by Ca2+, but was not completely blocked by EGTA. Simultaneous addition of 1 mM ATP with 1 mM MgCl2 (Mg-ATP) in the presence of Ca2+ reduced this release. However, in spite of the existence of Mg-ATP, the stimulation of PM-induced amylase release was caused by Ca2+ in a concentration-dependent manner (10(-7)-10(-3) M). These results suggest that Ca2+ and Mg-ATP should participate as important regulators in the exocytotic interaction between secretory granules and plasma membranes in this system. Furthermore, the differences between our system and intact cells are also discussed.

Adenosine Triphosphate↗
PubMed1992

Effects of cycloheximide and actinomycin D on radiation-induced apoptotic cell death in the developing mouse cerebellum.

Effects of cycloheximide and actinomycin D on radiation-induced cell death in the external granular layer (EGL) of the cerebellum were studied in vivo. Newborn mice were exposed to 0.24 Gy gamma-radiation, and dying cells which exhibited pyknosis of nuclei in the EGL were examined at various post-irradiation periods. The number of pyknotic cells began to increase 3 h after irradiation, reached a peak incidence at 6 h, and then gradually fell to the sham-irradiated level by 18 h. When pups were injected with cycloheximide 1 h after irradiation, cell death was suppressed for 6 h, but a peak mortality as high as in the case of radiation alone was attained at 15 h after irradiation. When pups were treated with cycloheximide twice, at 1 and 6 h after irradiation, cell death did not occur for 15 h, but then the incidence rose to a level similar to that after irradiation alone. These findings showed that radiation-induced cell death in the EGL is suppressed by cycloheximide until the chemical is metabolized. Hence, death is by apoptosis which is known to require macromolecular synthesis, and the 'signal' for apoptosis in the cell persists for at least 15 h after irradiation. On the other hand, actinomycin D injected immediately before or after irradiation did not affect the initiation of cell death; actinomycin D alone induced cell death.

Animals↗
PubMed1992

Effects of hyperthermia induced by microwave irradiation on brain development in mice.

Pregnant mice were exposed to 2.45 GHz of microwave radiation for 15 or 20 min on day 13 of gestation. The highest maternal core temperature during the exposure did not exceed 42.5 degrees C. Pregnant females also were immersed in hot water at 42 degrees C for 15 min to compare thermal effects on brain development. Animals were killed 9 hours after treatment, and the pyknotic cells in the ventricular zone of telencephalon were counted. The respective incidences of these cells in the groups exposed to microwaves for 15 and 20 min were 1.83% and 3.06%. Microwave radiation for 20 min had an effect that was comparable to that of immersion in 42 degrees C hot water for 15 min. In addition, some animals were examined on day 18 of gestation, and some of their offspring were examined at 6 weeks of age in an examination of long-term effects. Brain weight for the group exposed to microwaves for 20 min was significantly lower than for the control group, and the numerical density of the neurons in the cerebrum was higher. We concluded that microwave radiation at the dose tested mainly has a thermal effect.

Animals↗
PubMed1992

Enzyme-linked immunosorbent assay for the detection of Fusobacterium necrophorum antibody in bovine sera.

An enzyme-linked immunosorbent assay (ELISA) with HCl heat extracted antigen of Fusobacterium necrophorum was developed for the detection of antibody in bovine sera. Optimal conditions for antigen concentration and dilution of bovine serum were established. Pretreatment of positive reference serum with the antigens of different bacteria demonstrated no decrease, whereas the serum pretreated with F. necrophorum antigens revealed a decrease in the ELISA values. The apparent difference in ELISA values was observed between the sera derived from cattle infected and not infected with Fusobacterium necrophorum. These findings indicate that the ELISA detects the antibody to F. necrophorum in bovine sera.

Animals↗
PubMed1991

Ca(2+)-independent phospholipase A2 activity associated with secretory granular membranes in rat parotid gland.

Phospholipase A2 activity was detected in a secretory granular fraction (SG) purified by Percoll gradient centrifugation from rat parotid gland using [3H]phosphatidylcholine (PC) as a substrate. High activity of this enzyme was observed at neutral pH. The enzyme was activated by Triton X-100 and did not require Ca2+ for its activity. In the absence of Ca2+, its apparent Km for exogenous PC was 28 microM while it was slightly increased by adding 5 mM CaCl2 (73 microM). Furthermore, the enzyme was located essentially in a granular membrane fraction separated from granular lysate. The deacylation activities were also detected in other subcellular fractions, which showed a different detergent-susceptibility or pH-dependency from that in SG. These results suggest that secretory granules have membrane-bound phospholipase A2 which has properties different from that found in other organelles.

Acylation↗
PubMed1991

Developmental disturbance of rat cerebral cortex following prenatal low-dose gamma-irradiation: a quantitative study.

Pregnant rats were exposed to a single whole-body gamma-irradiation on Day 15 of gestation at a dose of 0.27, 0.48, 1.00, or 1.46 Gy. They were allowed to give birth and the offspring were killed at 6 or 12 weeks of age for microscopic and electron microscopic examinations of the cerebrum. Their body weight, brain weight, cortical thickness, and numerical densities of whole cells and synapses in somatosensory cortex were examined. Growth of the dendritic arborization of layer V pyramidal cells was also examined quantitatively with Golgi-Cox specimens. A significant dose-related reduction in brain weight was found in all irradiated groups. Neither gross malformation nor abnormality of cortical architecture was observed in the groups exposed to 0.27 Gy. A significant change was found in thickness of cortex in the groups exposed to 0.48 Gy or more. Cell packing density increased significantly in the group exposed to 1.00 Gy. Significant reduction in the number of intersections of dendrites with the zonal boundaries were found in the groups exposed to 0.27 Gy or more. There was no difference in the numerical density of synapses in layer I between the control and irradiated groups. These results suggested that doses as low as 0.27 Gy could cause a morphologically discernible change in the mammalian cerebrum.

Animals↗
PubMed1991

18q-syndrome with cleft lip and palate. A clinically diagnosed case.

A case of a child with 18q-syndrome was encountered. The patient presented cleft lip and palate, narrow auditory canals, overlapping fingers, undescended testes and micropenis. Chromosome analysis demonstrated partial deletion of the long arm of one chromosome 18 in the patient and normal chromosomes in the parents. A cheiloplasty for repair of bilateral complete cleft lip was performed.

Chromosome Aberrations↗
PubMed1991

Experimental epithelial dysplasia produced by excisional wounding and application of Trp-P-2 in the hamster tongue.

All 10 groups of hamsters received excision of the tip of tongue. Subsequently, 3 groups in which tongues were treated with Trp-P-2 (3-amino-1-methyl-5H-pyrido[4,3-b] indole) and then again excised in their tips followed by no treatment or by additional applications of DMSO or Trp-P-2, showed moderate to severe epithelial dysplasia. One group in which tongues were not treated and then again excised followed by applications of Trp-P-2, exhibited very slight epithelial dysplasia. However, one group in which tongues were treated with DMSO and then again excised followed by additional applications of DMSO, did not show any pathological changes. The remaining 5 groups in which tongues were treated with DMSO or Trp-P-2 or received no treatment and then not excised followed by no treatment or by additional applications of DMSO or Trp-P-2, also did not show any pathologic changes. These results clearly indicated that Trp-P-2 treatment together with two times of excisional wounding could produce lingual epithelial dysplasia in hamsters.

Animals↗
PubMed1991

Experimental odontogenic tumors produced by ethylnitrosourea injections and mechanical injuries.

The present study was carried out to investigate odontogenic tumor induction in the rats by injections of carcinogen N-ethyl-N-nitrosourea (ENU) coupled with incisional wounds. The animals which received local injections of ENU in the region of incisor tooth germ of the right mandible every other day for 19 days after birth coupled with incisional wounding in the same region at 2 and 8 days, developed odontogenic carcinomas. However, the animals which were given local injections of ENU in the region of incisor tooth germ but did not receive incisional wounds, showed no pathologic changes. The animals which received both local injections of physiologic salt solution and incisional wounds in the same manner as mentioned above, did not exhibit any pathologic changes. The present results indicate that local administration of carcinogen ENU coupled with mechanical injuries, namely incisional wounding, caused the production of odontogenic carcinomas in the incisor region of the mandible in rats.

Ameloblasts↗
PubMed1991

Cisplatin-induced injury to calcium uptake by mitochondria in glutathione-depleted slices of rat kidney cortex.

Changes in functional activities of mitochondria from kidney cortical slices incubated with cisplatin and the glutathione depletor diethylmaleate were examined. Diethylmaleate, which decreased the glutathione level in the slices, enhanced the cisplatin-induced decreases in glutathione level and calcium uptake in the mitochondria. The movement of cisplatin into mitochondria in the slices was not affected by diethylmaleate. These results suggest that the depressions in glutathione level and calcium uptake by cisplatin in mitochondria are enhanced by a decrease in cytoplasmic glutathione.

Animals↗
PubMed1991

The iron chelator deferoxamine prevents cisplatin-induced lipid peroxidation in rat kidney cortical slices.

We evaluated the effect of the iron chelator deferoxamine on lipid peroxidation produced by the nephrotoxic antineoplastic drug cisplatin in rat kidney cortical slices. The addition of deferoxamine to the incubation medium prevented such lipid peroxidation in the incubated slices. Treatment of rats with deferoxamine inhibited the increase in lipid peroxidation caused by cisplatin in the medium. These results suggest that iron may be a causal agent of cisplatin-induced lipid peroxidation.

Animals↗
PubMed1991

Split-dose effect of X-irradiation on the induction of cell death in the fetal mouse brain.

Pregnant mice were exposed to whole-body X-irradiation at a total dose of 0.25 Gy split into two 0.125 Gy exposures at 0.5-, 2- or 6-hour interval on day 13 of pregnancy. Fetuses were obtained from dams at various post-exposure periods and their brains were processed for microscopy. Undifferentiated neural cells in the ventricular zone of telencephalon (ventricular cells) were examined, and incidence of cells involved in pyknosis was evaluated. The curves of incidence of pyknotic cells plotted against time after the exposures to two split-doses at 0.5-hour and 2-hour intervals overlapped that of a single 0.25 Gy exposure; they had a common peak at 8-10 hours after the first exposure. Following two 0.125 Gy exposures at 6-hour interval, two peaks with similar elevations from background levels appeared at 6 and 12 hours after the first exposure. These results indicated that low-dose X-irradiation shows simply additive effects of split doses on cell death, without induction of adaptive response of ventricular cells of the telencephalon at day 13 of pregnancy in mice.

Animals↗
PubMed1991

Parasitism of Toxocara canis larvae in Japanese quails by inoculation of the ascarid eggs.

The distribution of T. canis larvae and pathological changes caused by them were studied in Japanese quails orally inoculated with 1,500, 4,000 or 15,000 embryonated eggs. Larvae were distributed mainly in the liver and, to lesser extent, in the muscles, brain, eyes and other organs. The number of larvae varied from 7 to 3,346, and from 1 to 288 in the liver and muscles (breast and legs), respectively. A small number of larvae were also recovered from the heart, gizzard, brain and eyes. In the groups of quails inoculated with 4,000 or 15,000 eggs, small white foci were observed on the surface of the liver 6 or 12 hr after inoculation. Histopathological examinations revealed necrotic lesions, leukocytic infiltration, granuloma and nodular lesions. The pathological changes became more serious with the large size of inoculum and days after inoculation.

Animals↗
PubMed1991

Sensitive phases for teratogen-induced developmental defects in the brain.

Developmental stage-dependent susceptibility to teratogens and sensitive period can be regarded as one of the essential points which characterize teratogenesis. In this paper, emphasis is given to a review of our studies on the critical developmental stage for induction of histogenetic disorders of the cerebral cortex and on the high vulnerability of developing neural cells to teratogenic agents. The undifferentiated ventricular cells in the mammalian fetal telencephalon are particularly vulnerable to various cytotoxic agents at the time when the ventricular cells start to differentiate into cerebral cortical neurons and the cortical plate appears. This period is day 13 of gestation in mice, day 15 in rats and 8 weeks after fertilization in humans. This developmental stage of the brain corresponds to the period of highest sensitivity for induction of cerebral cortical disorders observed postnatally both in laboratory animals and in humans. One of the significant factors determining the period of highest sensitivity of the ventricular cells could be a certain initial phase of cytodifferentiation in G1 and G0 phase cells prior to their actual morphological differentiation.

Animals↗
PubMed1991

[Rapidly progressive periodontitis combined with plasma cell gingivitis: a case report].

A case of rapidly progressive periodontitis combined with plasma cell gingivitis with marked enlargement of the gingiva was presented. Clinically, in the plasma cell gingivitis, the gingiva appear red, friable and bleed easily; usually it does not induce loss of attachment. Histologically, a dense infiltration of the normal plasma cells in the connective tissue is a common finding. A hypersensitivity reaction to some antigens, often flavorings or spices, is generally recognized. In this case, a rapidly progressive loss of attachment was observed, so rapidly progressive periodontitis was diagnosed. Differential diagnosis of the plasma cell gingivitis could be determined by histological and ultrastructural examination. Allergens, however, could not be identified. Conventional periodontal therapy, including intensive plaque control, could not cure the plasma cell gingivitis completely but recurrence of gingival enlargement and loss of attachment could be well controlled.

Adolescent↗
PubMed1991

[Changes in granulocyte elastase caused by the use of ulinastatin during anesthesia for renal transplantation].

In patients with renal failure, releases of chemical mediators having inhibitory influences on organs and circulatory system have been observed. Therefore, in long-term dialysis patients, it is necessary to consider the biocompatibilities of the equipment for dialysis. On 13 cases of renal transplantations, we measured the pre- and post-operative changes of granulocyte elastase (GE) and evaluated the effect of ulinastatin. The renal transplanted patients receiving a long-term dialysis showed higher GE values than that of normal patients even before the operation. During the anesthesia, GE increased gradually and further increased after the operation. In patients given ulinastatin during anesthesia, the increase in GE during the operation was suppressed but an increase after the operation was observed. The renal transplanted patients are easily infectible. Therefore, it is useful to measure GE pre- and post-operatively for earlier diagnosis of the postoperative infection and septicemia. The administration of ulinastatin can inhibit the increase of GE. It seems that ulinastatin increases renal blood flow and improves renal function.

Adult↗
PubMed1990

Developmental brain abnormalities accompanied with the retarded production of S-100 beta protein in genetic polydactyly mice.

The homozygotes of a mouse strain with genetic polydactyly (Polydactyly Nagoya, Pdn) exhibit various brain malformations including exencephaly in about 20%. In the present report, the brains of homozygotes (Pdn/Pdn) which were not exencephalic were examined morphologically and biochemically. Homozygous newborn brains showed hydrocephaly, some gyri on the cerebral hemisphere, absence of the corpus callosum, absence of the commissura anterior, absence of the fornix and commissura fornicis, protuberance of the cortical tissue from the brain surface, and abnormal architecture of the hippocampus. An irregular mass of olfactory nerve was observed on the cribriform plate, and the olfactory bulb was deficient. From these findings, we considered Pdn/Pdn as a kind of arhinencephalic mouse. Nervous tissue-related proteins, S-100 alpha, S-100 beta, creatine kinase B (CK-B), neuron-specific gamma-enolase, guanosine triphosphate binding proteins (Go alpha, Gi2 alpha and G beta) were immunoassayed in the cerebrum of Pdn/Pdn embryos and newborns. Among the protein analysed, only S-100 beta of Pdn/Pdn showed a significantly lower level than that of +/+ cerebrum during the observation period. The newborn brains were examined immunohistochemically using S-100 alpha, S-100 beta, CK-B, Go alpha and NSE antibodies. We could find no differences in the staining patterns among the Pdn/Pdn, Pdn/+ and +/+ brains.

Animals↗