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Biomedical subjects

Y Ninomiya

Publications and source records attributed to Y Ninomiya.

At least 19 recordsLinked to original sources
PubMed2007

Influence of temperature on taste perception.

Daily experience tells us that temperature has a strong influence on how we taste. Despite the longstanding interest of many specialists in this aspect of taste, we are only starting to understand the molecular mechanisms underlying the temperature dependence of different taste modalities. Recent research has led to the identification of some strong thermosensitive molecules in the taste transduction pathway. The cold activation of the epithelial Na(+) channel and the heat activation of the taste variant of the vanilloid receptor (TRPV1t) may underlie the temperature dependence of salt responses. Heat activation of the transient receptor potential channel TRPM5 explains the enhancement of sweet taste perception by warm temperatures. Current development of methods to study taste cell physiology will help to determine the contribution of other temperature-sensitive events in the taste transduction pathways. Vice versa, the analysis of the thermodynamic properties of these events may assist to unveil the nature of several taste processes.

Animals↗
PubMed2003

Distribution of the collagen IV isoforms in human Bruch's membrane.

AIMS: To determine the distribution of the alpha1 to alpha6 chains of type IV collagen in Bruch's membrane of the human posterior pole. METHODS: Cryosections (10 micro m) from 18 human eyes (20 months to 83 years old) were acid treated, blocked with 10% normal goat serum, incubated for 1 hour with monoclonal antibodies against type IV collagen isoform specific peptides at 1:75 dilution, and visualised with an ABC staining kit. RESULTS: In Bruch's membrane, the alpha1(IV) and alpha2(IV) chains were identified in retinal pigment epithelial (10/18 = 55%) and choriocapillaris basement membranes (18/18 = 100%); the alpha3(IV), alpha4(IV), and alpha5(IV) chains were also found in the retinal pigment epithelial basement membrane (13/18 = 72%). In the choroid, the alpha1(IV) and alpha2(IV) chains were detected in the blood vessels (18/18=100%). The alpha6(IV) chain was not identified in any sections. CONCLUSION: The heterogeneous distribution of alpha1-2(IV) and alpha3-5(IV) in Bruch's membrane could give insights into the function of this structure in health, ageing, and diseases such as age related macular degeneration.

Adolescent↗
PubMed2002

Salivary cystatins influence ingestion of capsaicin-containing diets in the rat.

Dietary capsaicin consumed by rats over several days induces cystatin-like substances in submandibular saliva. Yet the physiological role of these salivary proteins has not been thoroughly investigated. Salivary cystatins in the rat submandibular glands are known to be induced by chronic treatment with the sympathetic beta-agonist, isoproterenol. In the present study, the possible roles of the salivary proteins on food intake were examined by comparing consumption of a capsaicin-adulterated (0.05%) diet in rats with and without isoproterenol pretreatment (0.1 and 5.0 mg/kg, 5 days). Electrophoretic analysis performed prior to feeding trials revealed that the group pretreated with 5 mg/kg isoproterenol had large amounts of cystatin in the saliva compared with the group pretreated with 0.1 mg/kg isoproterenol and control group. The group treated with 5 mg/kg isoproterenol showed greater consumption of the capsaicin-adulterated diet than the other groups until the 3rd day of trials. Bilateral removal of the submandibular and sublingual glands neutralized the effects of isoproterenol. Induction of salivary cystatins by isoproterenol treatment was not mimicked by systemic and intragastric administration of capsaicin. These results suggest that cystatins are included in the salivary proteins induced by capsaicin and that they contribute to enhanced ingestion of the capsaicin diet. Induction of salivary cystatins may be triggered by irritation of the oral mucosa by capsaicin.

Analysis of Variance↗
PubMed2002

Neural activities in the substantia nigra modulated by stimulation of the orofacial motor cortex and rhythmical jaw movements in the rat.

Neurons related to jaw movements in the substantia nigra pars reticulata were explored by examining changes in their neural activities in response to electrical stimulation of the orofacial sensorimotor cortex and during rhythmical jaw movements induced by mechanical stimulation applied to the oral cavity in the rat. Out of 80 neurons tested, 59 showed changes in their firing patterns of activities in response to the electrical stimulation of the cortex. The responding neurons were mainly located in the dorsolateral part of the substantia nigra pars reticulata. The substantia nigra pars reticulata neurons showing responses were classified into the following five types according to their response patterns: (1) an inhibition preceded by an early excitation and followed by a late excitation (n = 26), (2) an inhibition preceded by an early excitation but not followed by a late excitation (n = 7), (3) an inhibition not preceded by an early excitation but followed by a late excitation (n = 2), (4) an inhibition without early or late excitations (n = 7) and (5) an excitation without an inhibition (n = 17). Out of 18 neurons responding to the cortical stimulation, 11 (61.1%) increased or decreased their neural activities during rhythmical jaw movements. Some of these neurons had a projection to the lateral part of the superior colliculus (n = 5) and/or to the parvicellular reticular formation (n = 2). These results provide first neurophysiological evidence for neurons in the dorsolateral part of the substantia nigra pars reticulata with inputs from and outputs to the areas related to jaw movements. These neurons may participate in the control of jaw movements in the rat.

Action Potentials↗
PubMed2001

Hypoxia down-regulates endostatin production by human microvascular endothelial cells and pericytes.

Endostatin is a potent anti-angiogenic factor derived from the C-terminal region of collagen XVIII and is implicated in the regulation of physiological and pathological angiogenesis. In this study, reverse transcription-polymerase chain reaction analysis of poly(A+) RNA demonstrated the presence of mRNA for collagen XVIII in human endothelial cells (EC) and pericytes, the very constituents of microvessels wherein angiogenesis takes place. Enzyme immunoassay revealed that both cell types liberated endostatin into culture media and that the endostatin levels were decreased by hypoxia, the principal cause of angiogenesis. Northern and Western blot analyses revealed that while the collagen XVIII/endostatin mRNA levels were invariant between hypoxic and normoxic conditions, the collagen XVIII protein levels in EC and pericytes decreased by hypoxia. Further, exogenously administered intact endostatin was significantly decreased when it was incubated with hypoxic conditioned media of endothelial cells or pericytes, but not with normoxic media. The results suggest that the reduction of autocrine endostatin may take an active part in hypoxia-driven angiogenesis.

Angiogenesis Inhibitors↗
PubMed2001

A comparative study of three cranial sensory ganglia projecting into the oral cavity: in situ hybridization analyses of neurotrophin receptors and thermosensitive cation channels.

Peripheral cranial sensory nerves projecting into the oral cavity receive food intake stimuli and transmit sensory signals to the central nervous system. To describe and compare the features of the cranial sensory ganglia that innervate the oral cavity, i.e., the trigeminal, petrosal, and geniculate ganglia (TG, PG, and GG, respectively), in situ hybridization was conducted using riboprobes for neurotrophin receptors (TrkA, TrkB, and TrkC), a neurotransmitter (substance P), and ion channels important for thermosensation (VR1 and TREK-1). In TG, all in six probes yielded positive signals to various extent in intensity and frequency. In addition, a strong correlation between the expression of VR1 and those of TrkA and substance P was observed as in the case of the dorsal root ganglia. In PG, positive signals to all six probes were also detected, and the correlation of expression was similar to that shown by TG. On the other hand, most cells in GG were positive to the TrkB probe, and a small number of cells were positive to the TrkC probe, but no significant signal was observed for the other four probes. These results indicate that TG and PG consist of cells that are heterogeneous in terms of neurotrophin requirement and somatosensory functions, and that GG seems to consist mainly of a homogeneous cell type, gustatory neurons. In conclusion, TG, PG, and GG, show gene expression characteristics intrinsic to the three ganglia. It is also concluded that TG and a portion of PG project several types of somatosensory nerves. This is consistent with the finding that GG and a portion of PG project gustatory nerves.

Animals↗
PubMed2001

Postnatal development of choline acetyltransferase activity in the rat laterodorsal tegmental nucleus.

Cholinergic neurons in the laterodorsal tegmental nucleus (LDT) have important roles in the regulation of sleep or waking in adult animals. In neonatal animals, sleep is largely occupied by paradoxical sleep. To investigate the relation between the cholinergic neurons in the LDT and the development of neonatal sleep, we dissected the LDT of rat by micropunch method at postnatal day 1--45 and measured the activity of choline acetyltransferase (ChAT). Either specific or total activity of ChAT was weak in the first week, increased strikingly in the second week and then moderately thereafter. The time course of the increase in ChAT activity correlates well to that of the decrease in the amount of paradoxical sleep or body twitches after birth.

Acetyl Coenzyme A↗
PubMed2001

Ion selectivities of the Ca(2+) sensors for exocytosis in rat phaeochromocytoma cells.

1. The ion selectivities of the Ca(2+) sensors for the two components of exocytosis in rat phaeochromocytoma (PC12) cells were examined by measurement of membrane capacitance and amperometry. The cytosolic concentrations of metal ions were increased by photolysis of caged-Ca(2+) compounds and measured with low-affinity indicators benzothiazole coumarin (BTC) or 5-nitrobenzothiazole coumarin (BTC-5N). 2. The Ca(2+)-induced increases in membrane capacitance comprised two phases with time constants of 30--100 ms and 5 s. Amperometric events reflecting the exocytosis of large dense-core vesicles occurred selectively in the slow phase, even with increases in the cytosolic Ca(2+) concentration of > 0.1 mM. 3. The slow component of exocytosis was activated by all metal ions investigated, including Cd(2+) (median effective concentration, 18 pM), Mn(2+) (500 nM), Co(2+) (900 nM), Ca(2+) (8 microM), Sr(2+) (180 microM), Ba(2+) (280 microM) and Mg(2+) (> 5 mM). In contrast, the fast component of exocytosis was activated by Cd(2+) (26 pM), Mn(2+) (620 nM), Ca(2+) (24 microM) and Sr(2+) (320 microM), but was only slightly increased by Ba(2+) (> 2 mM) and Co(2+) and not at all by Mg(2+). 4. The fast component, but not the slow component, was competitively blocked by Na(+) (median effective concentration, 44 mM) but not by Li(+), K(+) or Cs(+). Thus, the Ca(2+) sensor for the fast component of exocytosis is more selective than is that for the slow component; moreover, this selectivity appears to be based on ionic radius, with cations with radii of 0.84 to 1.13 A (1 A = 0.1 nm) being effective. 5. These data support a role for synaptotagmin--phospholipid as the Ca(2+) sensor for the exocytosis of large dense-core vesicles and they suggest that an additional Ca(2+)-sensing mechanism operates in the synchronous exocytosis of synaptic-like vesicles.

Animals↗
PubMed2001

Analysis of pain-related somatosensory evoked magnetic fields using the MUSIC (multiple signal classification) algorithm for magnetoencephalography.

We evaluated the effectiveness of the Multiple Signal Classification (MUSIC) algorithm by analysing pain-related somatosensory-evoked magnetic fields (SEFs) by 148-channel whole-head-type magnetoencephalography. MUSIC peaks of middle latency components were located around the primary somatosensory cortex (SI), contralateral to the stimulated finger. Long latency components were located around the bilateral secondary somatosensory cortices (SII) and cingulate gyri. Peaks at the SII and cingulate gyri were more prominent on very painful and moderately painful stimulation than on weak stimulation. The results were in very good agreement with results from single dipole estimation. These findings suggest that the MUSIC algorithm could be a useful tool for analysis of pain-related SEFs.

Adult↗
PubMed2001

The NC1 domain of collagen IV encodes a novel network composed of the alpha 1, alpha 2, alpha 5, and alpha 6 chains in smooth muscle basement membranes.

Type IV collagen, the major component of basement membranes (BMs), is a family of six homologous chains (alpha1-alpha6) that have a tissue-specific distribution. The chains assemble into supramolecular networks that differ in the chain composition. In this study, a novel network was identified and characterized in the smooth muscle BMs of aorta and bladder. The noncollagenous (NC1) hexamers solubilized by collagenase digestion were fractionated by affinity chromatography using monoclonal antibodies against the alpha5 and alpha6 NC1 domains and then characterized by two-dimensional gel electrophoresis and Western blotting. Both BMs were found to contain a novel alpha1.alpha2.alpha5.alpha6 network besides the classical alpha1.alpha2 network. The alpha1.alpha2.alpha5.alpha6 network represents a new arrangement in which a protomer (triple-helical isoform) containing the alpha5 and alpha6 chains is linked through NC1-NC1 interactions to an adjoining protomer composed of the alpha1 and alpha2 chains. Re-association studies revealed that the NC1 domains contain recognition sequences sufficient to encode the assembly of both networks. These findings, together with previous ones, indicate that the six chains of type IV collagen are distributed in three major networks (alpha1.alpha2, alpha3.alpha4.alpha5, and alpha1.alpha2.alpha5.alpha6) whose chain composition is encoded by the NC1 domains. The existence of the alpha1.alpha2.alpha5.alpha6 network provides a molecular explanation for the concomitant loss of alpha5 and alpha6 chains from the BMs of patients with X-linked Alport's syndrome.

Animals↗
PubMed2001

Molecular genetic identification of a candidate receptor gene for sweet taste.

A cDNA clone encoding a novel member of the putative taste receptor T1R family, designated T1R3, was isolated from circumvallate papillae of the mouse tongue using degenerate primers. Reverse transcription-polymerase chain reaction analysis showed predominant expression of the receptor in circumvallate papillae. In situ hybridization analysis revealed that T1R3 was expressed in a subset of taste receptor cells in taste buds and that the topographic distribution of T1R3 in various taste papillae was different from those of the other T1R members. Genetic mapping of T1R3 with a mouse/hamster radiation hybrid panel located the gene on the distal end of mouse chromosome 4 correlated with the Sac locus affecting sweet sensitivity of mice. Our results indicate that T1R3 may serve as the receptor for sweet perception in mice.

Amino Acid Sequence↗
PubMed2001

Loss of alveolar basement membrane type IV collagen alpha3, alpha4, and alpha5 chains in bronchioloalveolar carcinoma of the lung.

Type IV collagen, the major component of basement membrane (BM), is composed of six genetically distinct alpha(IV) chains. This study investigated for the first time the expression of these six alpha(IV) chains immunohistochemically, using alpha(IV) chain-specific monoclonal antibodies, in normal lung and in small (less than 2 cm in diameter) adenocarcinoma of the lung with a bronchioloalveolar growth pattern at the periphery. Small adenocarcinomas were histopathologically classified into three subtypes: bronchioloalveolar carcinoma (BAC) without collapse, BAC with collapse, and adenocarcinoma with bronchioloalveolar features. In normal lung, alveolar BM was composed of alpha1(IV)/alpha2(IV) chains and alpha3(IV)/alpha4(IV)/alpha5(IV) chains. In non-collapsed areas of BAC, alveolar BM was composed of linear alpha1(IV)/alpha2(IV) chains and discontinuous alpha3(IV)/alpha4(IV)/alpha5(IV) chains. In collapsed areas of BAC, alveolar BM was composed of linear and thick alpha1(IV)/alpha2(IV) chains only, because of the complete loss of alpha3(IV)/alpha4(IV)/alpha5(IV) chains. In invasive areas of adenocarcinoma with bronchioloalveolar features, alpha1(IV)/alpha2(IV) chains around the cancer cell nests were disrupted, in addition to the complete loss of alpha3(IV)/alpha4(IV)/alpha5(IV) chains. In conclusion, during the process of stromal invasion of lung adenocarcinoma, type IV collagen of alveolar BM is remodelled from the complete type, composed of alpha1(IV)/alpha2(IV)/alpha3(IV)/alpha4(IV)/alpha5(IV) chains, to the incomplete type, composed of only alpha1(IV)/alpha2(IV) chains, before the disruption of alpha1(IV)/alpha2(IV) chains. These findings may help to clarify the molecular mechanisms of cancer invasion.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed2001

Intelligent yeast strains with the ability to self-monitor the concentrations of intra- and extracellular phosphate or ammonium ion by emission of fluorescence from the cell surface.

Saccharomyces cerevisiae strains that respond to environmental changes and transmit the information by emission of fluorescence from the cell surface were constructed. The technique of cell surface engineering enabled the yeast cells to display enhanced cyan blue fluorescent protein (ECFP) or enhanced yellow fluorescent protein (EYFP) on the surface under the control of promoters that sense environmental changes. Two model promoters were examined in this study. For monitoring the intra- and extracellular concentrations of phosphate ion, the PHO5 promoter was chosen to display ECFP. The MEP2 promoter was used to display EYFP to sense the concentrations of ammonium ion. Fluorescence was observed by fluorescence microscopy and immunofluorescence microscopy, and the intensity was measured by a flow cytometer. The relationship between ion concentration inside and outside the cells was evaluated by the change in the rate of fluorescence. This S. cerevisiae system enables environmental changes to be transmitted as intra- and extracellular information using a suitable promoter functioning at real time and in a non-invasive manner.

Bacterial Proteins↗
PubMed2001

High-resolution genetic mapping of the saccharin preference locus (Sac) and the putative sweet taste receptor (T1R1) gene (Gpr70) to mouse distal Chromosome 4.

The Sac (saccharin preference) locus affecting mouse behavioral and neural responsiveness to sweeteners has been mapped to distal Chr 4. A putative sweet taste receptor, T1R1, has been recently cloned, and the gene encoding it, Gpr70, has also been mapped to mouse distal Chr 4. To assess Gpr70 as a candidate gene for Sac, we compared the Gpr70 sequences of C57BL/6ByJ and 129P3/J mouse strains with different alleles of Sac. Using Gpr70 sequence variation between the C57BL/6ByJ and 129P3/J strains, we conducted a high-resolution analysis of the chromosomal localization of the Gpr70 and Sac loci in the F2 hybrids and 129.B6-Sac partially congenic mice originating from these two strains. The Gpr70 gene maps proximal to Sac, which demonstrates that they are different loci.

Animals↗
PubMed2001

The inner ear of dogs with X-linked nephritis provides clues to the pathogenesis of hearing loss in X-linked Alport syndrome.

Alport syndrome is an inherited disorder of type IV collagen with progressive nephropathy, ocular abnormalities, and high-tone sensorineural deafness. In X-linked Alport syndrome, mutations in the COL4A5 gene encoding the alpha5 chain of type IV collagen lead to loss of the alpha3/alpha4/alpha5 network and increased susceptibility of the glomerular basement membrane to long-term damage. The molecular defects that underlie the otopathology in this disease remain poorly understood. We used a canine model of X-linked Alport syndrome to determine the expression of type IV collagen alpha-chains in the inner ear. By 1 month in normal adult dogs, the alpha3, alpha4, and alpha5 chains were co-expressed in a thin continuous line extending along the basilar membrane and the internal and external sulci, with the strongest expression along the lateral aspect of the spiral ligament in the basal turn of the cochlea. Affected dogs showed complete absence of the alpha3/alpha4/alpha5 network. The lateral aspect of the spiral ligament is populated by tension fibroblasts that express alpha-smooth muscle actin and nonmuscle myosin and are postulated to generate radial tension on the basilar membrane via the extracellular matrix for reception of high frequency sound. We propose that in Alport syndrome, the loss of the alpha3/alpha4/alpha5 network eventually weakens the interaction of these cells with their extracellular matrix, resulting in reduced tension on the basilar membrane and the inability to respond to high frequency sounds.

Animals↗
PubMed2001

Spatial and temporal gene expression in chondrogenesis during fracture healing and the effects of basic fibroblast growth factor.

Chondrogenesis is an essential component of endochondral fracture healing, though the molecular and cellular events by which it is regulated have not been fully elucidated. In this study, we used a rat model of closed fracture healing to determine the spatial and temporal expression of genes for cartilage-specific collagens. Furthermore, to determine the effects of basic fibroblast growth factor (bFGF) on chondrogenesis in fracture healing, we injected 100 microg recombinant human bFGF into the fracture site immediately after fracture. In normal calluses, pro-alpha1(II) collagen mRNA (COL2A1) was detected in proliferative chondrocytes beginning on day 4 after the fracture, and pro-alpha1(X) collagen mRNA (COL10A1) in hypertrophic chondrocytes beginning on day 7. In FGF-injected calluses, the cartilage enlarged in size significantly. On day 14, both COL2A1- and COL10A1-expressing cells were more widely distributed, and the amounts of COL2A1 and COL10A1 mRNAs were both approximately 2-fold increased when compared with uninjected fractures. Temporal patterns of expression for these genes were, however, identical to those found in normal calluses. The number of proliferating cell nuclear antigen-positive cells was increased in the non-cartilaginous area in the bFGF-injected calluses by day 4. The present molecular analyses demonstrate that a single injection of bFGF enhances the proliferation of chondroprogenitor cells in fracture callus, and thus contributes to the formation of a larger cartilage. However, maturation of chondrocytes and replacement of the cartilage by osseous tissue are not enhanced by exogenous bFGF, and this results in the prolonged cartilaginous callus phase. We conclude that, in the healing of closed fractures of long bones, exogenous bFGF has a capacity to enlarge the cartilaginous calluses, but not to induce more rapid healing.

Animals↗
PubMed2001

In vitro and in vivo expression of protoporphyrin IX induced by lipophilic 5-aminolevulinic acid derivatives.

We estimated the expression level of protoporphyrin IX (PpIX) induced by lipophilic 5-aminolevulinic acid (ALA) derivatives and observed its histological distribution by fluorescence microscopy. In vitro PpIX expression in Hepe2 cells was the highest when induced by ALA pentyl ester. This level was 2.8-fold higher than that induced by ALA after 4 h incubation and 2.5-fold higher than that after 24 h incubation. The differences between ALA pentyl ester and ALA were significant at both time points (P<0.01). In HeLa cells, ALA butyl ester showed the highest induction of PpIX, which was 2.6-fold higher than ALA after 4 h incubation and 3.5-fold higher after 24 h incubation. The differences were significant at both time points (P<0.01). In mice with squamous cell carcinoma, the in vivo expression of PpIX in the tumors was highest with ALA methyl ester, which was 1.3-fold higher than ALA. The difference was significant (P<0.01). The expression of PpIX by means of fluorescence microscopy was highest by ALA methyl ester. Under in vitro conditions, PpIX expression was efficiently induced by long chain ALA esters, while better in vivo PpIX induction was obtained with short chain ALA esters. In this study, ALA methyl ester was found to be the best among the ALA derivatives in inducing PpIX expression in vivo, and would be more effective in treatment of skin cancers than ALA.

Aminolevulinic Acid↗