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Y Ninomiya

Publications and source records attributed to Y Ninomiya.

At least 145 records · Page 8Linked to original sources
PubMed1997

Mammalian craniofacial embryology in vitro.

Our review demonstrates that the whole embryo culture system established by New and his colleagues, in combination with beneficial fluorescent dye cell-tracing techniques, has greatly contributed to many advancements in the field of mammalian craniofacial embryology, especially with regard to elucidating the developmental behavior of cephalic crest cells. In addition, based on recent results, further combining whole embryo culture with mandibular organ culture methods has allowed us to trace cranial crest cells for a much longer developmental period, i.e., presently up to the cap stage in odontogenesis.

Animals↗
PubMed1996

Ca2+-dependent exocytotic pathways in Chinese hamster ovary fibroblasts revealed by a caged-Ca2+ compound.

Ca2+-dependent exocytosis and endocytosis of Chinese hamster ovary (CHO) fibroblasts were investigated using capacitance measurement and rapid photolysis of a caged-Ca2+ compound, dimethoxynitrophenamine tetrasodium salt. CHO cells exhibited large and fast increases in membrane capacitance (1.9 +/- 1 picofarads, or 13 +/- 7% of total membrane area, mean +/- S.D., n = 37) upon Ca2+ jumps to [Ca2+]i larger than 20 microM. The fast exocytosis occurred with a delay (20-80 ms), and exhibited a rate constant that was strongly dependent on [Ca2+]i. The maximal rate constant of exocytosis was 2.8/s, and a half-maximal rate was achieved at 30 microM. The fast exocytosis was followed by rapid endocytosis in 28% of the cells. The endocytosis often began after a delay of 0.5-2 s. Ca2+ jumps also induced stepwise increases in membrane capacitance of 10-134 femtofarads in 40% of the cells, indicating fusion of large vesicles with diameters of 0.4-1.5 micron. The exocytosis of the large vesicles could selectively be induced with smaller Ca2+ jumps (6-20 microM), and occurred slowly with a rate constant of 0. 3/s. These data indicate that CHO fibroblasts possess Ca2+-dependent exocytotic mechanisms. Moreover, two parallel exocytotic pathways may exist reminiscent of those of neurons and endocrine cells. A kinetic model was constructed to account for the fast exocytosis of CHO cells.

Acetates↗
PubMed1996

Two components of exocytosis and endocytosis in phaeochromocytoma cells studied using caged Ca2+ compounds.

1. Changes in membrane capacitance evoked by the rapid photolysis of a caged Ca2+ compound, DM-nitrophen or nitrophenyl-EGTA, were investigated in undifferentiated PC12 cells. They were interpreted as representing exocytosis and endocytosis. 2. The Ca2+ jumps evoked two components of exocytosis. Slow exocytosis was selectively evoked with small increases in intracellular Ca2+ concentration between 5 and 10 microM, while fast exocytosis preceded the slow one at [Ca2+]i greater than 10 microM. 3. The release rates of the two components of exocytosis depended steeply on [Ca2+]i. A half-maximal release rate was achieved at 8 and 24 microM for the slow and fast exocytoses, respectively. 4. Prior Ca2+ rises did not augment the fast exocytosis. 5. The fast exocytosis was often followed by a rapid decrease in membrane capacitance, representing endocytosis, after a delay of 0.5-2 s. The speed and delay in the fast endocytosis were Ca2+ dependent. Amounts of the fast endocytosis tended to balance with those of the fast exocytosis evoked by the same Ca2+ jumps. 6. The slow exocytosis was followed by a sluggish endocytosis that was associated with large capacitance steps indicative of secretory processes involving large dense-core vesicles. The onset of the slow endocytosis exhibited a complex Ca2+ dependence. The amounts of the slow endocytosis appeared to parallel those of the slow exocytosis. Prior induction of the slow exocytosis gave rise to selective excess retrieval of membrane during the slow endocytosis. 7. These data indicate the existence of two distinct populations of secretory vesicles in PC12 cells. They seem to couple selectively with specific endocytotic mechanisms. Our data suggest that the two vesicles belong to two distinct secretory pathways.

Animals↗
PubMed1996

Contribution of early-emigrating midbrain crest cells to the dental mesenchyme of mandibular molar teeth in rat embryos.

Teeth are formed by reciprocal interactions between the epithelium and mesenchyme in the first pharyngeal arch. Although the contribution of midbrain and hindbrain crest cells to the first pharyngeal arch has been previously examined in rodent embryos, no direct evidence exists that these cells are actually involved in the dental mesenchyme. In order to elucidate the contribution of the cranial neural crest cells in tooth formation, we first identified the emigration sites and stages providing the crest cells that migrate to the presumed tooth-forming region of the mandibular prominence. Focal labeling with DiI was performed at the midbrain and anterior hindbrain crests in rat embryos, and the labeled embryos were cultured for 30 or 60 hr. The resultant migration patterns indicated that posterior midbrain crest cells emigrating by the end of the 4-somite stage predominantly migrated to the region where tooth buds normally develop. Second, we established a new type of long-term culture system in which whole embryo culture is followed by a mandibular organ culture. Using this system, rat embryos were maintained from the early-somite stage and the molars in the explants were able to reach the bud stage within 8 days. Finally, to ascertain if posterior midbrain crest cells emigrating by the end of the 4-somite stage were involved in the dental mesenchyme, these cells were labeled with DiI and processed for the long-term culture. Labeled crest cells were clearly detectable in the dental mesenchyme. These findings indicate that the early-emigrating posterior midbrain crest cells contribute to mandibular molar tooth development in rat embryos.

Animals↗
PubMed1996

Analysis of DNase I hypersensitive site of the ELP gene.

The chromatin structure of the ELP gene was analyzed by DNase I hypersensitivity. A strong DNase I hypersensitive site (Y1DH) was identified at the exon 1 region of the ELP gene in steroidogenic Y1 cells. A strong DNase 1 hypersensitive site (ECDH2) downstream of the exon 8 of the ELP gene and a weak DNase 1 hypersensitive site (ECDH1) upstream of the exon 2 of the ELP gene was identified in undifferentiated EC cells. These differences of the DNase I hypersensitive sites may be related to the differential expression of ELP isoforms in Y1 cells and EC cells. In addition, the gel shift assay and DMS protection assay revealed that ELP binds to the ECDH2 region.

3T3 Cells↗
PubMed1996

Amiloride inhibition of chorda tympani responses to NaCl and its temperature dependency in mice.

Inhibitory effects of amiloride on salt responses of the chorda tympani nerve and its temperature dependency were compared among three inbred strains of mice (C57BL, BALB and 129). In C57BL mice, lingual treatment with amiloride significantly suppressed responses to 0.1-1.0 M NaCl at two different temperatures, 24 +/- 2 degrees C and 12 +/- 2 degrees C. The magnitude of the amiloride-inhibited component of NaCl response was slightly larger at the higher temperature. In contrast, in BALB mice, amiloride suppression of NaCl responses was observed only at the lower temperature. No such suppression was exhibited by 129 mice at either temperature levels. These results suggest that there exist at least two different amiloride-sensitive receptor components for NaCl in mice: one is more sensitive to NaCl at the higher temperature, and the other is more sensitive at the lower temperature. It is hypothesized, C57BL mice possess the former (or both) component(s), whereas BALB mice have the latter one. The 129 strain may be lacking both components.

Administration, Oral↗
PubMed1996

A synthetic oestrogen antagonist, tamoxifen, inhibits oestrogen-induced transcriptional, but not post-transcriptional, regulation of gene expression.

Oestrogen (E2) regulates the expression of its target genes at transcriptional and post-transcriptional levels. To clarify the mechanism of E2-induced post-transcriptional regulation, with attention to the involvement of the oestrogen receptor (ER), we studied the effect of tamoxifen (TAM), a synthetic E2 antagonist that inhibits ER-mediated transcription, on E2-induced transcriptional and post-transcriptional regulation of the chicken ovalbumin (OVA) gene in chick oviducts. Run-on analysis with oviduct nuclei isolated from E2-treated chicks showed that TAM treatment completely blocked E2-induced transcription of the OVA gene within 24 h without affecting ER gene expression. Likewise, the rate of transcription fell to below the limit of detection after E2 withdrawal from the chicks. Reflecting the transcription rate, OVA mRNA accumulated linearly in E2-treated chicks, and E2 withdrawal caused a rapid loss of OVA mRNA. However, in the chicks treated with TAM and E2, OVA mRNA was degraded slowly over 48 h with a half-life of 24 h, suggesting that TAM does not inhibit E2-induced mRNA stabilization. Moreover, E2-induced mRNA stabilization was observed even when transcription of the OVA gene was blocked by a transcription inhibitor. Western-blot analysis showed that the remaining OVA mRNA was translatable. Thus the present study indicates that E2 regulates expression of the OVA gene via distinct pathways at transcriptional and post-transcriptional levels.

Animals↗
PubMed1996

Experimental anti-GBM glomerulonephritis induced in rats by immunization with synthetic peptides based on six alpha chains of human type IV collagen.

The anti-glomerular basement membrane (GBM)-nephritis-inducing activity of six synthetic peptides having an amino acid sequence consisting of the six alpha chains of human type IV collagen was examined by injecting the peptides into rats. The peptides consisted of 27 amino acid residues from the non-collagenous domain (NC1) of the alpha 1 to alpha 6 chains and were non-consensus sequences sandwiched between two consensus sequences near the carboxyl terminus. Each peptide was coupled to keyhole limpet haemocyanin and injected with adjuvant into the footpads of 20 female WKY/NCrj rats. The number of rats with proteinuria (over 10.0 mg of urinary protein/15 h) and haematuria was 2 with the alpha 3 peptide, 8 with the alpha 4 peptide, and 1 with the alpha 5 peptide. Histological changes seen in the glomeruli were characteristic of those in anti-GBM nephritis. Linear deposition of rat IgG along the GBM was observed in five rats injected with the alpha 4 peptide. A nephritogenic monoclonal antibody against the alpha 4 peptide was established using lymph node cells from a rat injected with the alpha 4 peptide. The results indicate that alpha 4(IV)NC1 is a potent nephritogenic antigen like alpha 3(IV)NC1, which has already been recognized as a primary target antigen in Goodpasture's syndrome.

Amino Acid Sequence↗
PubMed1996

Effects of cerebroventricle administration of acidic fibroblast growth factor on conditioned taste aversion learning in rats.

Wistar strain rats were given acidic fibroblast growth factor (aFGF) or denatured aFGF into their cerebroventricle before taste aversion conditioning for saccharin solution. Animals administered with aFGF showed significantly lower aversion threshold for saccharin at the 1st day and preference ratios for saccharin vs distilled water at the 4th, 6th, and 7th day after the conditioning than those administered with denatured aFGF. These results suggests that aFGF in the cerebrospinal fluid facilitates acquisition of the conditioned taste aversion learning.

Animals↗
PubMed1996

Effects of feeding on conditioned avoidance responses in rats.

Possible effects of feeding on learning were studied by comparing learned avoidance rates among three groups of Wistar rats that were given a diet at 1 h (1-h pretest group) and 5 h (5-h pretest group) before and immediately after (post-test group) the conditioned avoidance test. Learned avoidance rates during eight test sessions were higher in the order of the 1-h pretest, post-test, and 5-h pretest groups. This suggests that both pre- and post-test (training) feeding facilitates acquisition of conditioned avoidance learning presumably based on neurohumoral processes influenced by available glucose concentrations.

Animals↗
PubMed1996

Nephritogenicity and alpha-chain composition of NC1 fractions of type IV collagen from bovine renal basement membrane.

Nephritogenicity (anti-GBM-nephritis-inducing activity) and alpha-chain composition of globular-do-main (NCI) fractions of type IV collagen from bovine renal, pulmonary, and placental basement membranes (BMs) was examined by injecting these fractions with adjuvant into WKY/NCrj rats and by Western blotting using epitope-defined monoclonal antibodies to the six different alpha chains of type IV collagen. A purified nephritogenic fraction from renal BM contained alpha 1-alpha 6(IV)NCI, whereas a non-nephritogenic fraction contained only alpha 1-alpha 2(IV)NCI. Renal and pulmonary NCI had strong nephritogenic activity: placental NCI had weak activity. The renal and pulmonary fractions contained alpha 1-alpha 6(IV)NCI, and the placental fraction had a large amount of alpha 1-alpha 2(IV)NCI and a very small amount of alpha 3-alpha 6(IV)NCI. Immunohistochemical study of bovine renal BM with the monoclonal antibodies revealed that bovine glomerular BM contained alpha 1-alpha 5(IV) chains, but not the alpha 6(IV) chain. The absence of alpha 6(IV) chain in glomerular BM in bovine and in humans indicates that alpha 6(IV) chain is not a target antigen of anti-GBM nephritis. Nephritogenicity is apparently a property of alpha 3-alpha 5(IV)NCI.

Animals↗
PubMed1996

Absence of alpha 6(IV) collagen in kidney and skin of X-linked Alport syndrome patients.

To identify the abnormalities of the type IV collagen alpha 6 chain, alpha 6(IV), in Alport syndrome, we examined renal and skin tissue using rat monoclonal antibodies against non-consensus amino acid sequences of alpha 6(IV). Immunofluorescence of normal human kidney and skin tissue revealed linear alpha 6(IV) staining in the basement membrane (BM) of Bowman's capsule, in some tubules, and also in the epidermal BM. Renal specimens from five male patients of four families with X-linked Alport syndrome showed no reactivity for alpha 6(IV) in Bowman's capsules and tubules. In these patients, alpha 1(IV) and alpha 2(IV) were normal, whereas alpha 3(IV), alpha 4(IV), and alpha 5(IV) were absent from the BMs of the kidney. In skin tissue of male patients, neither alpha 5(IV) nor alpha 6(IV) were detected. The epidermal BM of female heterozygotes with X-linked Alport syndrome showed a mosaic staining for alpha 5(IV) and alpha 6(IV). These findings indicate that, in addition to a disturbed alpha 3(IV)-alpha 4(IV)-alpha 5(IV) network, patients with X-linked Alport syndrome have abnormalities in alpha 6(IV) of the renal and epidermal BMs at the protein level.

Amino Acid Sequence↗
PubMed1996

Retinotomy and foveal translocation for surgical management of subfoveal choroidal neovascular membranes.

PURPOSE: To report a surgical procedure for excising subfoveal neovascular membranes and translocating the fovea in an attempt to maintain the function of the sensory retina to preserve central vision, based on the technique of macular relocation. METHODS: Three patients with subfoveal neovascular membranes underwent surgery for the creation of a nearly 180-degree retinal flap, removal of neovascular tissue, and reattachment and rotation the retina with translocation of the fovea over functional pigment epithelium. RESULTS: In one patient with age-related macular degeneration, best-corrected visual acuity improved from 20/200 preoperatively to 20/20 postoperatively. A second patient, also with age-related macular degeneration, experienced a worsening of best-corrected visual acuity from 20/700 to 20/ 2,000. In the third patient, with myopic degeneration, best-corrected visual acuity improved from 20/700 to 20/70. Complications included the development of epimacular proliferation in two eyes and retinal detachment and neovascular glaucoma in one eye. CONCLUSION: The technique of foveal translocation has the potential for restoring central visual function in certain patients with subfoveal neovascular membranes.

Aged↗
PubMed1996

Taste in chimpanzee: I. The summated response to sweeteners and the effect of gymnemic acid.

The purpose of this study was to investigate further with electrophysiological and behavioral techniques the similarity between the sense of taste of humans and chimpanzees, especially with regard to the effects of gymnemic acid. Gymnemic acid (GA) is a powerful suppressor of sweet taste in humans but lacks this ability in nonprimates and lower primates. The summated taste responses from the chorda tympani nerve were recorded in nine adult chimpanzees, Pan troglodytes. The results show that all tested compounds that taste to humans elicited nerve responses in chimpanzees. GA suppressed or abolished the response to all sweeteners, but had no effects on the responses to the nonsweet compounds. The suppression varied from complete abolishment (aspartame, saccharin), to about 50% reduction (xylitol). When the effect of GA was tested on concentration series, 20% remained of the response to sucrose, whereas the responses to aspartame and saccharin were basically abolished. Higher concentrations of GA suppressed more. The effects of GA developed also in the presence of saccharin, but seemed less pronounced. The behavioral results were obtained with a one-bottle preference technique before and after GA. The results demonstrated that after exposure of the tongue to GA, the animals' liking for sweet diminished. These results parallel psychophysical and electrophysiological findings in humans. The way GA suppressed sweet taste in chimpanzees added one more characteristic to those that set chimpanzees apart from monkeys and close to humans.

Animals↗
PubMed1996

The 160k alpha 1(IV) chain, a short form of a type IV collagen polypeptide, of bovine lens capsule retains the NC1 domain.

We recently reported that the bovine lens capsule contained a shorter alpha 1(IV) chain (160k) as a major polypeptide in addition to the 180k alpha 1(IV) chain [J. Biochem. (1995) 117, 1298-1304]. Two experiments were performed to examine whether or not the 160k polypeptide retained the carboxyl-terminal NC1 domain. On immunoblotting analysis with a monoclonal antibody (H11) raised against the NC1 domain of the human alpha 1(IV) chain [positions 1643-1650; near the carboxyl-terminal end of the human alpha 1(IV) chain], the 180k and 160k polypeptides showed identical immunoreactivity, suggesting that the two chains had the same human alpha 1(IV) collagen NC1 domain sequence. Another monoclonal antibody (H21) specific for the NC1 domain of human alpha 2(IV) did not react with these polypeptides, but with the bands corresponding to 175k and 155k. The 160k polypeptide was selectively solubilized from bovine lens capsules, leaving the other major polypeptides, 180k and 175k, insoluble. The 160k polypeptide was separated by preparative electrophoresis. Bacterial collagenase digestion of the separated 160k polypeptide produced collagenase-resistant segments of about 29k and 30k in size based on globular standards. These sizes corresponded well with those of the NC1 domains of type IV collagen alpha chains (25-30k). The results indicated that the 160k polypeptide retained the carboxyl-terminal NC1 domain of the alpha 1(IV) chain. In turn, the 20k polypeptide of the amino-terminal region or the 7S domain of 180k alpha 1(IV) would have been excised to yield 160k alpha 1(IV), assuming that the 160k alpha 1(IV) chain is a processed form of the 180k alpha 1(IV) one and not an alternatively spliced chain of the alpha 1(IV) gene.

Amino Acid Sequence↗
PubMed1996

Steroid hormones differentially induce transcription of the chicken ovalbumin gene, but stabilize the mRNA with the same half-life.

The stabilization of chicken ovalbumin (OVA) mRNA by different classes of steroid hormones (estrogen, progesterone, glucocorticoid, and androgen) was studied in the oviducts of chicks treated with combinations of four steroids. The combination of estrogen with progesterone, glucocorticoid, or androgen enhanced the induction of the OVA gene more than did estrogen alone. Run-on analysis of the isolated oviduct nuclei to measure the transcription rate of the OVA gene showed that the enhanced induction of the OVA gene by the combined hormone treatments was partly caused by an increased rate of transcription. The half-life of OVA mRNA as determined using a transcription inhibitor (actinomycin D) was estimated to be about 24 h irrespective of the hormone treatment, though the half-life was about 6 h in the absence of hormones. These results suggested that the prolongation of the half-life of OVA mRNA by steroid hormones is constant irrespective of differential transcription rates of the OVA gene.

Animals↗
PubMed1996

Immunohistochemical detection of p53 tumor suppressor protein in porokeratosis.

We examined 9 Japanese cases of porokeratosis (4 of the plaque type, 2 of disseminated superficial actinic porokeratosis, 2 of disseminated superficial porokeratosis, and one of giant porokeratosis) for the expression of p53 tumor suppressor protein immunohistochemically, using two anti-p53 antibodies, CM1 and DO1. The same results were obtained with both antibodies. The epidermis central to the cornoid lamellae was positive in 8 of 9 specimens. On the other hand, the peripheral epidermis was positive in 2 of the 9 cases. The epidermis beneath the cornoid lamellae was positive in 3 of the 9 cases. The frequency of p53 positivity was significantly higher in the epidermis central to cornoid lamellae over that beneath or peripheral to them (Fisher's exact probability test, p < 0.05). The majority of squamous cell carcinoma cells arising on giant porokeratosis stained with CM1 and DO1. These data may suggest that the abnormal p53 expression has some relevance to the skin carcinogenesis of porokeratosis.

Adult↗