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Y Ninomiya

Publications and source records attributed to Y Ninomiya.

At least 199 records · Page 11Linked to original sources
PubMed1994

Co-expression of collagen types II and X mRNAs in newly formed hypertrophic chondrocytes of the embryonic chick vertebral body demonstrated by double-fluorescence in situ hybridization.

Collagen types II and X mRNAs have been demonstrated simultaneously in newly formed hypertrophic chondrocytes of embryonic chick vertebral cartilage using a double-fluorescence in situ hybridization technique. Digoxigenin- and biotin-labelled type-specific collagen II and X cDNA probes were used. In the embryonic chick vertebra at stage 45, two different fluorescence signals (Fluorescein isothiocyanate and Rhodamine)--one for collagen type II mRNA, the other for type X mRNA--showed differential distribution of the two collagen mRNAs in the proliferating and hypertrophic chondrocyte zones. Several layers of newly formed hypertrophic chondrocytes expressing both collagen types II and X genes were identified in the same section as two different fluorescent colour signals. Low levels of fluorescent signals for collagen type II mRNA were also detected in the hypertrophic chondrocyte zone. Cytological identification of maturing chondrocyte phenotypes, expressing collagen mRNAs, is easier in sections processed by non-radioactive in situ hybridization than in those subjected to radioactive in situ hybridization using 3H-labelled cDNA probes. This study demonstrates that double-fluorescence in situ hybridization is a useful tool for simultaneously detecting the expression of two collagen genes in the same chondrocyte population.

Animals↗
PubMed1994

Apical cell escape from the neuroepithelium and cell transformation during terminal lip fusion in the house shrew embryo.

The house shrew embryo has many cells in the ventricular lumen and on the luminal surface of the fusing terminal lip of the cephalic neural tube. The origin and fate of these cells were studied by means of light and electron microscopy, and by DiI labeling in a whole-embryo culture system. The cells appeared at stage 11A and persisted until stage 12A. Most of the cells seemed to originate from the neuroepithelium, as shown by frequent observations of epithelial cell escape and DiI labeling analysis. The cells on the luminal surface sometimes showed apoptotic features, but were not subjected to phagocytosis. Some of the escaping cells seemed to migrate to the ventral part of the prosencephalic neuropore and insert themselves into it. Others separated from the luminal surface and floated into the lumen. It seems likely that the floating cells either become autolyzed, or else change into macrophage-like cells, the latter alternative being supported by the results of DiI labeling. The macrophage-like cells actively phagocytosed the other degenerating cells and apoptotic bodies. These observations suggest that the apical escape of cells may play an important role in the remodeling of the neural fold during the terminal lip fusion, and that early neuroepithelial cells may have the potential to become cells with vigorous phagocytic activity, like macrophages.

Animals↗
PubMed1994

Glossopharyngeal denervation alters responses to nutrients and toxic substances.

Functional roles of the glossopharyngeal (GL) nerve on food and fluid intake were studied by examining effects of the GL denervation on two biologically different activities induced by specific diets using mice and rats. First, we examined whether GL section alters the acceptability of a bitter tasting essential amino acid, L-lysine (Lys), by Lys-deficiency in mice. The aversion threshold for Lys, normally about 3 uM in mice, increased to about 300 uM when mice were fed the Lys-deficient diet for 10 days. This increase of the Lys aversion threshold (increase of acceptability for Lys) by Lys-deficiency was also evident in mice with the chorda tympani denervation but was not observed in mice with the GL denervation. Next, we examined whether GL section alters the induction of a salivary protein, cystatin S (a cysteine proteinase inhibitor), by a diet containing papain (a cysteine proteinase) in rats. GL denervation largely inhibited the induction of cystatin S in the rat submandibular glands by papain. These results collectively suggest that chemosensory information conveyed by the GL nerve plays important roles on recognition of both nutrient and toxic compounds in the diet and induction of biological responses that protect the animal from both nutritional deficiency and exogenous toxic compounds.

Animals↗
PubMed1994

Bitter taste in single chorda tympani taste fibers from chimpanzee.

We have found earlier that chimpanzee chorda tympani taste fibers fall into groups that conform with the human taste qualities. This study focuses on bitter taste and its relation to sweet taste. Eight fibers were classified as bitter fibers according to their responses to 31 stimuli. The stimuli included the bitter compounds quinine, denatonium benzoate and caffeine. The results indicate a clear dichotomy between the bitter and sweet fibers. Sweet fibers never responded to the bitter compounds. However, in addition to their responses to the above compounds, some of the bitter fibers were stimulated by other compounds. Most prominent were responses to NaCl-amiloride mixture, KCl and xylitol. In most cases the cause could be assumed to be a bitter taste in the compound. These results suggest that the bitter and sweet tastes are conveyed in specific and separate groups of nerve fibers in the chimpanzee. Because of the closeness between chimpanzee and human, this finding has implications on the question of taste coding in human and the concept of taste qualities.

Animals↗
PubMed1994

Experimentally induced intermittent sinusoidal heart rate pattern and sleep cycle in fetal lambs.

OBJECTIVE: Intermittent sinusoidal heart rate pattern, an early indicator of fetal anemia, has been speculated to have a positive correlation with fetal sleep cycles. To test this hypothesis, intermittent sinusoidal heart rate patterns were produced experimentally with arginine vasopressin in six methylatropinized fetal lambs that were demonstrating clear rapid-eye-movement and non-rapid-eye-movement sleep cycling. STUDY DESIGN: Eleven trials of arginine vasopressin infusion (40 to 160 mIU per body per minute) were performed on each of six chronically instrumented fetal lambs subsequent to parasympathetic blocking doses of methylatropine (300 to 400 micrograms). An intermittent sinusoidal heart rate pattern was observed in relation to fetal sleep cycles. RESULTS: Alteration between rapid-eye-movement and non-rapid-eye-movement sleep was observed in methylatropinized fetuses. In the six fetuses that showed intermittent sinusoidal heart rate patterns subsequent to arginine vasopressin infusion, the fetal heart rate tracing and fetal electrocorticogram demonstrated alternate sinusoidal pattern and reactive heart rate patterns during high- and low-voltage electrocorticogram activity, respectively. CONCLUSION: These findings support the hypothesis that fetal sleep cycling has a positive correlation with the periodic appearance of intermittent sinusoidal heart rate patterns.

Animals↗
PubMed1994

Variable fetal heart rate decelerations and electrocortical activities.

OBJECTIVE: The purpose of this study was to examine the influence of fetal behavioral states on baroreflex-mediated, variable fetal heart rate decelerations caused by umbilical cord occlusion. STUDY DESIGN: Five chronically instrumented fetal lambs were subjected to intermittent partial umbilical cord occlusion for 1 minute every 3 minutes, lasting 2 hours. Fetal behavioral states determined by electrocorticogram and heart rates by electrocardiogram were monitored continuously during these experiments. RESULTS: The fetuses exhibited an alteration between low- and high-voltage electrocorticogram states. Both the depth and width of the variable fetal heart rate decelerations were greater during high-voltage than during low-voltage electrocorticogram. CONCLUSION: Amplitude and duration of variable fetal heart rate decelerations are affected by fetal behavioral states.

Animals↗
PubMed1994

Different responsiveness of the chorda tympani and glossopharyngeal nerves to L-lysine in mice.

Differential taste responsiveness and functional role of the two taste nerves, the chorda tympani (CT) and the glossopharyngeal (GL), were studied in mice by examining neural and behavioral responses to an essential amino acid, L-lysine (Lys). Relative responses to Lys were larger in the GL than in the CT nerve. The neural threshold for the Lys response was about 2.5 log units lower in the GL (about 1.0 microM) than in the CT nerve (about 300 microM). An analysis of concentration-response relationships suggests a possibility that there are two different receptors (high and low affinity types) for Lys showing different dissociation constants. The posterior tongue region possesses both types, while the anterior region possesses only the low affinity type. Behavioral aversion threshold for Lys in intact mice, measured by use of a single bottle test, was about 1.0 microM. This threshold was the same as its neural threshold in the GL nerve. Animals whose bilateral GL nerves were sectioned showed a higher aversion threshold (about 300 microM) which was the same as the neural threshold in the CT nerve. An aversion conditioned to Lys significantly generalized to L-arginine in the intact and CT-denervated mice, and L-arginine and L-histidine in the GL-denervated mice, but the generalization pattern across various taste stimuli including the four basic taste stimuli (NaCl, HCl, quinine HCl and sucrose) did not prominently differ among the intact, the GL-denervated and CT-denervated mice. These results suggest that taste sensitivity to Lys is higher in the GL than in the CT nerve, but taste quality information for Lys conveyed by two taste nerves is not largely different.

Animals↗
PubMed1994

Repression of retinoic acid-induced transactivation by embryonal LTR binding protein.

The mechanism of repression of transcription by ELP, the embryonal long terminal repeat binding protein, was investigated. ELP represses the Moloney murine leukemia virus long terminal repeat by binding to a site which overlaps with a sequence element for retinoic acid receptor binding. This suggests possible competition of ELP with retinoic acid receptor for the same sequence elements. Oligonucleotides corresponding to ELP and/or retinoic acid receptor binding elements were placed upstream of the SV40 promoter and their effect on gene expression was analyzed by CAT assay. Elements which have affinity to both ELP and retinoic acid receptor were activated by retinoic acid receptor and these activations were repressed by ELP. An ELP binding element without affinity to retinoic acid receptor was insensitive to both activation by retinoic acid receptor and repression by ELP. Furthermore, cellular ELP binding elements and the Moloney leukemia virus long terminal repeat were activated by retinoic acid. These data suggest that one of the mechanism of transcriptional repression by ELP is competition for binding sites with transactivators such as retinoic acid receptors.

3T3 Cells↗
PubMed1994

Enhancement of gustatory nerve fibers to NaCl and formation of ion channels by commercial novobiocin.

Single fibers of the rat chorda tympani nerve were used to study the mechanism of action of the antibiotic novobiocin on salt taste transduction. In the rat, novobiocin selectively enhanced the responses of sodium-specific and amiloride-sensitive chorda tympani nerve fibers (N type) without affecting more broadly responsive cation-sensitive and amiloride-insensitive fibers (E type). In the presence of amiloride, novobiocin was ineffective at enhancing the response of N-type fibers toward sodium chloride. Novobiocin also increased the conductance of bilayers formed from neutral lipids by forming nonrectifying ion channels with low conductance (approximately 7 pS in 110 mM NaCl), long open times (several seconds and longer), and high cation selectivity. Amiloride did not alter either the conductance or kinetics of these novobiocin channels. These observations suggest that even though novobiocin is able to form cation channels in lipid bilayers, and possibly in cell membranes as well, its action on the salt-taste response is through modulation of existing amiloride-sensitive sodium channels.

Amiloride↗
PubMed1993

Differential taste responses of mouse chorda tympani and glossopharyngeal nerves to sugars and amino acids.

The differential taste responses of the chorda tympani (CT) and the glossopharyngeal (GL) nerves in preweanling and adult mice were examined by comparing magnitudes of responses to six sugars and 10 amino acids. The results indicate that for sugars the responses of the CT nerve are greater than those of the GL nerve while for umami and essential amino acids the responses of the GL nerve are greater than those of the CT nerve. Such differential taste responses of the CT and GL nerves does not prominently change during development.

Aging↗
PubMed1993

Identification of a novel collagen chain represented by extensive interruptions in the triple-helical region.

We have isolated mouse cDNA clones that encode a newly discovered collagenous polypeptide. Four overlapping cDNA clones contained an open reading frame of 1140 amino acid residues of collagenous and non-collagenous domains. The predicted polypeptide consists of 10 collagenous domains of various length that are interrupted by 11 noncollagenous domains. The overall structural arrangement differed significantly from reported collagen chains of 17 different types. Northern-blot analyses showed hybridization of the cDNA to 5.6kb and 4.8kb mRNA species in liver and kidney that are due to utilization of the two poly (A) signals.

Amino Acid Sequence↗
PubMed1993

Enhancement of murine gustatory neural responses to D-amino acids by saccharin.

Taste enhancing effects of sodium saccharin (Sac) on responses to particular sweet-tasting D-amino acids were found during the recording of mouse chorda tympani nerve responses to various taste stimuli in C57BL and BALB strains. In both strains, responses to D-tryptophan and D-histidine significantly increased (167.7-216.7% of control) after the stimulation with Sac as compared with those applied before Sac. In C57BL mice, the enhancement of Sac was also observed in response to D-phenylalanine (262.5% of control), but this was not the case for BALB mice, suggesting a prominent strain difference in response to D-phenylalanine, as shown previously. Responses to other sweet-tasting D- and L-amino acids and sugars were not enhanced by Sac. Enhancement of responses to these D-amino acids by Sac was also evident when responses to a mixture of D-amino acids and Sac were compared with the sum of responses to each component, although in this response analysis, the calculated magnitude of enhancement generally become smaller (135.7-180.5% of the sum) and enhancement of D-histidine responses disappeared. Except for Sac, various sweet-tasting amino acids and sugars and NaCl also tested showed no enhancing effect on D-phenylalanine responses in C57BL mice. Sac and D-amino acids, to which responses were enhanced by Sac, possess some common molecular features, namely ring structures. This structural similarity probably relates to the occurrence of the enhancement at the receptor sites.

Amino Acids↗
PubMed1993

cDNA isolation and partial gene structure of the human alpha 4(IV) collagen chain.

A novel collagen IV chain, alpha 4(IV), has recently been identified in basement membranes. We describe part of the primary structure of the human alpha 4(IV) polypeptide for the first time, which has been determined by cloning and sequencing of cDNAs encoding 241 amino acid residues of the COL domain and 231 residues of the NC1 domain. We also characterized a genomic DNA fragment containing 4 exons coding for the entire NC1 domain. Among five known alpha chains of collagen IV, the alpha 4(IV) chain is distinct from the other four chains. However, it is more similar to the alpha 2(IV) chain than to the alpha 1(IV), alpha 3(IV) and alpha 5(IV) chains in terms of amino acid sequence homology, domain structure of polypeptides and exon/intron structure of the genes, suggesting the presence of two phylogenetically distinct subclasses of collagen IV alpha chains; one composed of alpha 2 and alpha 4 chains and the other of alpha 1, alpha 3 and alpha 5 chains.

Amino Acid Sequence↗
PubMed1993

Intermittent sinusoidal heart rate pattern in vagotomized fetal lambs.

OBJECTIVES: Our aims were to investigate the relationship between the dose of arginine vasopressin and the pattern and duration of arginine vasopressin-induced sinusoidal fetal heart rate and to elucidate the correlation between intermittent sinusoidal heart rate and fetal sleep cycle. STUDY DESIGN: Sinusoidal heart rate pattern was induced by intravenous arginine vasopressin infusion at doses from 2 to 78 mlU/min into 11 chronically instrumented fetal lambs with bilateral cervical vagotomy. Appearance and frequency of sinusoidal heart rate, intermittent sinusoidal heart rate, and persistent sinusoidal heart rate were observed along with fetal tracheal pressure and electrooculogram. RESULTS: Intermittent sinusoidal heart rate response to low, medium, and high doses of arginine vasopressin appeared in 73.3%, 50.0%, and 33.3% of experiments, respectively. Intermittent sinusoidal heart rate appeared more frequently than persistent sinusoidal heart rate with lower doses (p < 0.02). When intermittent sinusoidal heart rate was induced, the incidence of sinusoidal patterns significantly increased during non-rapid-eye-movement sleep in comparison with rapid-eye-movement sleep (p < 0.01). CONCLUSIONS: Appearance of sinusoidal heart rate seems to be related to the dose of arginine vasopressin infused. Appearance of sinusoidal heart rate is also influenced by fetal sleep cycle; sinusoidal heart rate is more likely to appear during non-rapid-eye-movement sleep than during rapid-eye-movement sleep. These results support the hypothesis that persistent sinusoidal heart rate correlates with severity of stress.

Animals↗
PubMed1993

Rapid expression of collagen type X gene of non-hypertrophic chondrocytes in the grafted chick periosteum demonstrated by in situ hybridization.

We investigated the spatiotemporal localization of collagen Type I, II, and X mRNAs in the subcutaneously grafted chick periosteum by in situ hybridization. Five days after transplantation, we noted three types of histological findings in the grated tissue. (a) Developing trabecular bone exhibited proliferation of spindle-shaped fibroblastic cells and polygonal osteoblasts with moderate signals for collagen Type I mRNA. (b) Developing cartilage contained ovoid chondrocytes with a moderate level of both collagen Type I and II mRNAs. Differentiating chondrocytes with increased collagen Type X mRNA developed during the course of endochondral ossification. (c) An atypical mass of cartilage weakly stained with alcian blue was composed of a large number of non-hypertrophic chondrocytes exhibiting high signals for collagen Type X mRNA. At Day 9, we observed the typical histological features of both membranous and endochondral ossification. However, sparsely distributed chondrocytes with high signals for collagen Type X mRNA were also demonstrated in osteoid and/or woven bone. The phenotype of chondrocytes showing rapid expression of collagen Type X gene derived from grafted periosteum seems to participate in the important role of endochondral bone formation in the early stage of fracture repair.

Animals↗
PubMed1993

[Antitumor activity of various cytostatics in mice bearing murine advanced tumors].

Antitumor activities of cytostatics such as 5-FU, 5'-DFUR, cyclophosphamide (CPA), ACNU, CDDP, mitomycin C (MMC) and doxorubicin (DXR) were compared in mice bearing four different murine-tumor models at two different stages of the tumor growth. All cytostatics tested suppressed the tumor growth in most of the four tumors, colon 26 carcinoma, UV 2237 fibrosarcoma, Ehrlich carcinoma and Meth A fibrosarcoma, when the tumor sizes were small (early transplant). When given to mice bearing advanced tumors, 5-FU, CDDP, MMC and DXR were effective only at the higher doses, showing toxicity. In contrast, 5'-DFUR was equally effective against both most of early and advanced tumors except for advanced Meth A against which higher doses of 5'-DFUR were needed. CPA and ACNU equally suppressed the growth of early transplant and advanced tumors of Meth A, although higher doses were needed against advanced tumors of three others. 5'-DFUR was also effective against tumor cachexia (colon 26) and spontaneous metastasis (Lewis lung carcinoma), which are characteristically observed in mice bearing advanced tumors. CPA also showed an anticachectic activity, though the activity was weaker than that of 5'-DFUR. These results suggest that 5'-DFUR and CPA can be used in both intensive and adjuvant chemotherapies.

Animals↗
PubMed1993

Corneal endothelial modulation: a factor released by leukocytes induces basic fibroblast growth factor that modulates cell shape and collagen.

PURPOSE: We have previously reported that corneal endothelial modulation takes place when rabbit corneal endothelial (CE) cells are exposed to corneal endothelium modulation factor (CEMF) released by polymorphonuclear leukocytes (PMN) (Kay, E. P., L. Rivela, and Y. G. He, 1990. Invest Ophthalmol Vis Sci. 31:313-322). The modulation was involved in phenotypic switches from polygonal cell shape to fibroblastic morphology and from basement membrane collagen (type IV-rich) synthesis to fibrillar collagen (type I-rich) synthesis. In the current study, we tested the effect of several growth-modulating factors on corneal endothelial modulation. METHODS: The effect of basic fibroblast growth factor (bFGF) on cell proliferation was measured by [3H]thymidine incorporation into DNA and cell numbers. Collagen expression was determined by SDS-polyacrylamide gel electrophoresis and by Northern blot analysis. Transcription rate was determined by nuclear run-off assay. Basic fibroblast growth factor synthesis was analyzed by immunoblot assay and quantitated by ELISA assay. Immunofluorescent staining was used for in vivo localization of bFGF and its receptors. RESULTS: Basic fibroblast growth factor (bFGF) supplemented with heparin is able to modulate the same phenotypes as observed in CEMF-induced modulation. Basic fibroblast growth factor has a marked stimulatory effect on cell proliferation, as shown by increased cell numbers and [3H]thymidine incorporation into DNA. It also has a strong effect on modulation of cell morphology and collagen phenotypes; the polygonal endothelial cells are induced to assume an elongated shape, and fibrillar collagen synthesis (types I and V) is turned on by bFGF, whereas type IV synthesis is markedly reduced. Such modulating effects of bFGF are augmented by CEMF. Furthermore, CEMF significantly increases production of bFGF in CE cells; the CEMF-treated CE cells synthesized bFGF seven times more than did the control cells. The induced bFGF has a major peptide band of 18.4 kD. Immunohistochemical analysis demonstrates that rabbit corneal endothelium in vivo stains for bFGF, while Descemet's membrane requires prior digestion with proteinase K. In situ localization of bFGF receptors demonstrates that high affinity receptors for bFGF are present in corneal endothelium. However, neither transforming growth factor (TGF-beta), epidermal growth factor (EGF), nor retinoic acid (RA) alters qualitative collagen phenotypes; rabbit CE cells continue to synthesize type IV collagen as a predominant species under the influence of these factors. Unlike rabbit CE cells, bovine CE cells in culture produce predominantly fibrillar collagens (I, III, and V). Transforming growth factor enhances type III collagen synthesis and induces type I collagen, but none of these factors affects type IV collagen synthesis by bovine cells. Neither steady-state levels of collagen RNA nor relative transcription rates of the collagen genes are changed significantly by TGF-beta, EGF, or RA in either rabbit or bovine CE cells. CONCLUSIONS: These findings suggest that bFGF is able to simultaneously modulate three phenotypic aspects of rabbit CE cells (cell proliferation, cell shape, and collagen expression). Furthermore, CEMF induces de novo synthesis of biologically active bFGF, indicating that bFGF, through the action of CEMF, is the key molecule during corneal endothelial modulation, which ultimately leads to corneal fibrosis (retrocorneal fibrous membrane).

Animals↗