PubMed Health⌕ Search

Biomedical subjects

T Komuro

Publications and source records attributed to T Komuro.

At least 37 records · Page 2Linked to original sources
PubMed1998

Immunohistochemical study of the c-kit expressing cells and connexin 43 in the guinea-pig digestive tract.

The distribution of the c-kit receptor expressing cells and gap junction protein, connexin (Cx) 43 in the guinea-pig stomach (antrum), small intestine (jejunum) and colon (ascending) was studied by immunohistochemistry. The anti-c-kit protein immunopositive cells were regularly observed in the myenteric region throughout all three organs. The immunopositive cells were also sparsely distributed in the circular muscle layer of both the stomach and the colon, but not in the small intestine. They were densely located in the regions of the deep muscular plexus (DMP) of the small intestine and submuscular plexus (SMP) of the colon. In contrast, strong immunoreactivity to anti-Cx 43 antibody was observed in almost the entire thickness of the circular muscle layer of the stomach and the small intestine, but not in the colon. Dense immunoreaction deposits were observed in the region of the DMP and SMP. However, only very weak immunoreactivity to anti-Cx 43 antibody was detected in the myenteric region of all three organs. These results suggest that the c-kit receptor expressing cells or interstitial cells of Cajal (ICC) in the myenteric region of the three organs, and in the SMP of the colon, are poorly coupled with the bulk of circular muscle tissue by gap junctions, while ICC in the DMP and in the circular muscle layer of the stomach couple well with the surrounding muscle tissue.

Animals↗
PubMed1998

Further observations on the gap-junction-rich cells in the deep muscular plexus of the rat small intestine.

Interstitial cells forming many large gap junctions in the region of the deep muscular plexus of the rat small intestine were studied by electron microscopy and by three-dimensional cell models reconstructed from serial ultrathin sections. Two different profiles of cells were observed. Cells of the first profile are characterized by an elongated cell shape and by less electron-dense cytoplasm, containing many mitochondria, well-developed Golgi apparatus and free ribosomes. They mainly connect with smooth muscle cells of the main circular layer. In a three-dimensional cell model, the total area of the gap junctions occupies 1.3% of the cell surface. Cells of the second profile are characterized by the frequent occurrence of slender cytoplasmic processes, higher electron-dense cytoplasm, containing mitochondria, Golgie apparatus and well-developed rough endoplasmic reticulum, and numerous caveolae on the cell membrane. In this cell model, gap junctions occupy 0.8% of the cell surface. The ratio of gap junctions with the same profile of cells to the total gap junction area is 37.7%, which is more than three times greater than the 9.9% in cells of the first profile. These cells were closely associated with nerve terminals. It is likely that these cells with different profiles constitute subtypes with each other and cooperate for regulation of intestinal motility via the transmission of nerve signals.

Animals↗
PubMed1998

Ultrastructural characterization of interstitial cells of Cajal in the rat small intestine using control and Ws/Ws mutant rats.

Interstitial cells in the myenteric plexus and the deep muscular plexus of the small intestine of the c-kit mutant rats (Ws/Ws) and their normal siblings (+/+) were studied. c-Kit immunoreactivity was detected in two regions corresponding to the myenteric plexus and the deep muscular plexus in the jejunum of +/+ rats, while no immunoreactivity was detected in Ws/Ws rats. Using electron microscopy, two types of gap junction-forming interstitial cells were found in association with the myenteric plexus in +/+ rats: one type characterized by a typical fibroblastic ultrastructure, and the other characterized by numerous mitochondria and less electron-dense cytoplasm. Since the latter were greatly reduced in Ws/Ws rats, it was suggested that these cells correspond to c-kit-expressing cells, i.e. interstitial cells of Cajal in the myenteric plexus region. In contrast, two types of interstitial cells in the region of the deep muscular plexus were observed with no difference between +/+ and Ws/Ws rats. Probable interstitial cells of Cajal in this region were characterized by a basal lamina and numerous caveolae as well as large gap junctions that interconnect with each other and with the smooth muscle cells. We concluded that interstitial cells of Cajal in the rat intestine are heterogeneous in ultrastructure, c-kit dependency in the cell maturation, and functional role.

Animals↗
PubMed1998

Gender determination from dental pulp by using capillary gel electrophoresis of amelogenin locus.

Gender of dental pulp DNA was determined by the capillary gel electrophoresis (CGE) method with amelogenin locus as a marker. The analysis of the male sample resulted in two peaks, a Y-locus standard sample was added and the CGE method repeated. This resulted in an amplification of the second peak and judging from the difference between the allele sizes of the X and Y loci, it was confirmed that the first peak was for the X and the second for the Y locus. The female sample was then analyzed and one peak was observed. As before the X-locus standard sample was added to this sample and resulted in an amplification of the peak, thus verifying it to be the X locus. The CGE method was conducted for 10 male and 10 female samples and double peaks verified the male sample, while one peak verified the female sample. Gender was thus correctly determined in all cases.

Amelogenin↗
PubMed1998

[Repeat structure of DYS389 locus].

In the DYS389 locus, tetranucleotide repeat units (CTGT and CTAT) connect complicatedly, and repeat sequences to show polymorphism are found in two sections. Because non-repetitive sequence including the same sequence as forward primer exists among these repeat sequences, a pair of primers for the DYS389 locus give two amplification products (DYS389 I and DYS389 II), both of which are polymorphic. These polymorphisms come from the differences in the number of CTGT and CTAT repeats. DNA was extracted from the dental pulp of 68 males and saliva of 48 males, and amplified for the DYS389 locus. And then the length polymorphisms and the repeat structures were examined. As results of denaturing polyacrylamide gel electrophoresis, alleles 8-12 appeared in the DYS389 I locus, while alleles 24 29 appeared in the DYS389 II locus, with alleles 11 and 27 showing the most frequent. As results of sequencing of many samples, we confirmed that the repeat structures of the DYS389 I and II alleles were (CTGT)3 (CTAT)r and (CTGT)p (CTAT)q (CTGT)3 (CTAT)r, respectively. DYS389 I alleles were related to the repeat numbers of r (r = 8-12), and DYS389 II alleles to the repeat numbers of p + q + r (p = 4.5; q = 11-14; r = 8-12). Even the same DNA size of DYS389 II alleles had different repeat structures, indicating that DYS389 is effective for the purposes of individual identification and paternity testing.

Alleles↗
PubMed1997

Ultrastructural identification of the c-kit-expressing interstitial cells in the rat stomach: a comparison of control and Ws/Ws mutant rats.

Interstitial cells in the circular muscle layer of the stomach of the Ws/Ws mutant rat, which lacks c-kit-expressing cells, and its siblings have been studied by electron microscopy. In the sibling control rats, two types of interstitial cells are found lying in close association with nerve bundles. Cells of the first type are characterized by electron-dense cytoplasm containing abundant mitochondria, granular endoplasmic reticulum, and Golgi apparatus. Intermediate filaments are richly distributed throughout the perinuclear region and the cell processes. Caveolae, subsurface cisterns, and indistinct basal lamina are observed along the cell membrane. The most conspicuous feature of this cell type is the existence of many large gap junctions that interconnect with the same type of cell, smooth muscle cells, or cells of the second type. Cells of the second type show an ultrastructure similar to fibroblasts, viz., a well-developed Golgi apparatus and granular endoplasmic reticulum whose cisterns often show a dilated form and contain flocculent material. Unlike typical fibroblasts, however, cells of this type also form many gap junctions with cells of the first type and smooth muscle cells. Both types of cells are observed in close apposition to nerve varicosities. Since cells of the first type are absent in the Ws/Ws mutant rat, we concluded that they correspond to c-kit-expressing cells and to interstitial cells of Cajal.

Animals↗
PubMed1997

The involvement of a novel mechanism distinct from the thrombin receptor in the vasocontraction induced by trypsin.

1. The vasocontracting effect of a serine protease trypsin and its mechanisms were investigated by monitoring the isometric tension in endothelium-denuded rings of rabbit thoracic aortae and its effects on intracellular free Ca2+ concentrations ([Ca2+]i) in dispersed rabbit vascular smooth muscle cells with a Ca2+ indicator fura-2. The actions of trypsin were compared with those of thrombin. 2. Both thrombin and trypsin reversibly contracted aortic rings without endothelium in a concentration-dependent manner. The vasocontraction induced by trypsin was well correlated with the protease activity of trypsin actually added to the tissue baths containing the aortic rings and was completely blocked by soybean trypsin inhibitor and phenylmethylsulphonyl fluoride (PMSF), a serine protease inhibitor. 3. The trypsin-induced contractions of the aortic rings were not the result of irreversible damage to vascular smooth muscle cells, since the contractile responses induced by noradrenaline or 30 mM KCl were unaffected by pretreatment with trypsin. 4. The contractions induced by either thrombin or trypsin were reduced to about 30% of control responses after removal of extracellular Ca2+, indicating that most of the contraction is dependent on extracellular Ca2+. By contrast, the contractions induced by either of the proteases were reduced by an antagonist of L-type voltage-operated Ca2+ channels, nifedipine, to about 70% of control responses, indicating that both nifedipine-sensitive and -resistant Ca2+ channels are involved in these contractions. 5. In the aortic rings precontracted by a maximally effective concentration of thrombin, the second application of thrombin virtually failed to induce contractions but trypsin could still induce contractions amounting to 10% of control values by it's protease activity. 6. After the first application of a maximal concentration of thrombin, the second application of thrombin could not induce an increase in [Ca2+]i, but an application of trypsin could still induce an increase in [Ca2+]i in dispersed rabbit vascular smooth muscle cells. 7. These data suggest that in addition to activation of a thrombin receptor, trypsin can contract rabbit aortae by a proteinase-activated receptor 2 or a novel mechanism.

Animals↗
PubMed1997

Inhibitory effect of nitrovasodilators and cyclic GMP on ET-1-activated Ca(2+)-permeable nonselective cation channel in rat aortic smooth muscle cells.

1. In single vascular smooth muscle cells (VSMCs) isolated from the aortae of male Wistar rats, we examined the effects of nitric oxide (NO) donors such as sodium nitroprusside (SNP) and S-nitroso-N-acetyl-DL-penicillamine (SNAP), and 8-bromo-guanosine-3':5'-cyclic monophosphate (8-bromo-cyclic GMP) on endothelin-1 (ET-1)-activated Ca(2+)-permeable nonselective cation channel by use of whole-cell recordings of patch-clamp technique and monitoring of intracellular free Ca(2+)-concentration ([Ca2+]i) with fura-2 real-time digital microfluorometry. 2. ET-1 evoked an initial transient peak and a subsequent sustained elevation in [Ca2+]i. After removal of extracellular Ca2+. ET-1 evoked only an initial transient peak without a sustained phase. Nifedipine (1 microM), a specific blocker of the L-type voltage-operated Ca2+ channel (VOC), reduced the sustained phase to about 40% of the control level. The remaining part of the sustained phase was abolished by 30 microM SK&F 96365, a blocker of nonselective cation channels. 3. The nifedipine-resistant sustained elevation in [Ca2+]i was abolished by 100 microM SNP, 10 microM SNAP and 300 microM 8-bromo-cyclic GMP. Neither SNP, SNAP nor 8-bromo-cyclic GMP significantly affected the basal level of [Ca2+]i. 4. In a VSMC clamped at a holding potential of -60 mV with K+ in the pipette solution replaced by Cs+, application of 10(-8) M ET-1 induced an inward current with an increase in baseline fluctuation. With fluctuation analysis, unit conductance of the ET-1-induced current was calculated to be about 21 pS. The ET-1-induced current was linearly related to the membrane potentials with its reversal potential of -5.5 mV. 5. The ET-1-induced current was reversibly and completely inhibited by 30 microM SK&F 96365 or 500 microM Cd2+. The current inhibited by SK&F 96365 or Cd2+ was linearly related to membrane potential with a reversal potential of about -5 mV. 6. The ET-1-induced current was reversibly and completely inhibited by 100 microM SNP, 10 microM SNAP and 300 microM 8-bromo-cyclic GMP. The current inhibited by SNP, SNAP or 8-bromo-cyclic GMP showed linear voltage-dependence and reversed at about -5 mV. 7. In a bath solution in which all cations were replaced by 30 mM Ca2+ and 100 mM nonpermeant cation N-methyl-D-glucamine (NMDG), ET-1 evoked a current with a reversal potential of -11 mV, from which PCa2+/Pcs1 was calculated to be 2.1. This Ca2+ current was also abolished by 100 microM SNP, 10 microM SNAP and 300 microM 8-bromo-cyclic GMP. The current inhibited by SNP, SNAP or 8-bromo-cyclic GMP showed linear voltage-dependence and reversed at about -11 mV. 8. These results taken together indicate that NO through a cyclic GMP signalling pathway inhibits ET-1-activated Ca(2+)-permeable nonselective cation channels, thereby suppressing the sustained increase in [Ca2+]i. Thus, the present study indicates that this Ca(2+)-permeable nonselective cation channel is an important target for nitrovasodilators.

Animals↗
PubMed1997

Physiological role of Ca2+-permeable nonselective cation channel in endothelin-1-induced contraction of rabbit aorta.

We previously showed a role for a nonselective cation channel (NSCC) in the ETA-dependent action of endothelin-1 in mouse fibroblast and rabbit aortic smooth-muscle cell. To clarify the physiological significance of NSCCs in endothelin-1 (ET-1)-induced vasocontraction, we examined the effects of NSCC blockers such as mefenamic acid and SK&F 96365 on the contractions of deendothelialized rabbit aortic rings induced by a low (10[-10] M) or high (10[-8] M) concentration of ET-1. Mefenamic acid (< or =10[-3] M) had little effect on the contraction induced by 45 x 10(-3) M K+ or 1 x 10(-6) M Bay K-8644 in combination with 15 x 10(-3) M K+, indicating that it does not affect voltage-operated calcium channels (VOCs) and contractile mechanisms. The contraction by a low concentration of ET-1 was abolished after removal of extracellular Ca2+, but it was reduced only to 50% by a maximally effective concentration (10[-5] M) of nifedipine, an inhibitor of L-type VOCs (L-VOC). Mefenamic acid and SK&F 96365 inhibited the ET-1-induced contraction with 50% inhibitory concentration (IC50) values of 10(-4) M and 2 x 10(-5) M, respectively, and abolished it at 10(-3) M and 10(-4) M. By contrast, nifedipine, mefenamic acid, or SK&F 96365 had little effect on the contraction by a high concentration of ET-1. The contraction induced by a low or high concentration of ET-1 was abolished by an ETA antagonist, BQ-123, but not by an ETB antagonist, BQ-788. These results demonstrate that the contraction induced by ET-1 is totally mediated exclusively by ETA, but that Ca2+ entry through NSCCs in addition to L-VOCs plays an important role in contractions induced by low concentrations of ET-1, whereas it plays only a minor role in contractions induced by high concentrations of ET-1.

Animals↗
PubMed1996

Anti-c-kit protein immunoreactive cells corresponding to the interstitial cells of Cajal in the guinea-pig small intestine.

Interstitial cells of Cajal (ICC) of the guinea-pig small intestine were studied with whole-mount preparations by using the zinc iodide-osmic acid method (ZIO) and immunohistochemistry for vimentin and c-kit receptor tyrosine kinase, and by electron microscopy. The myenteric ICC visualized with ZIO staining are immunopositive to both anti-c-kit antibody (ACK-2) and anti-vimentin antibody (V9), and constitute an independent cellular network from the myenteric plexus. Those cells are characterized by many mitochondria, abundant intermediate filaments, and surface cell membranes not covered with a basal lamina. They are connected with each other by gap junctions at tips of the cytoplasmic processes. It is concluded that the myenteric ICC of the guinea-pig intestine are fibroblast-like cells and that they correspond to the c-kit expressing cells regarded as the intestinal pacemaker.

Animals↗
PubMed1996

Neuro-muscular junctions of longitudinal and circular muscle fibers of the guinea-pig esophagus and their relation to myenteric plexus.

The structure of the neuromuscular junctions (NMJs) and their relation to the myenteric plexus were studied by zinc iodide-osmic acid (ZIO) staining and by scanning electron microscopy in the guinea-pig esophagus. The esophageal muscle coat consisted of the inner circular and outer longitudinal striated muscle fibers. The myenteric plexus was located between the two muscle layers along its whole length and was characterized by a loose and irregular network. It was demonstrated that unmyelinated nerve fibers form NMJs with the muscle fibers of both layers. The NMJs in the longitudinal muscle can be classified as 'plate' type, whereas those of the circular muscle resemble the 'grape' type. The different NMJs in the two muscle layers probably correspond to different contractile properties. The whole-mount preparations with ZIO staining also demonstrated that some NMJs receive minute branches from the myenteric plexus. Therefore, it is likely that the myenteric plexus is involved in the control of striated muscles of the guinea-pig esophagus.

Animals↗
PubMed1996

Characterization of the interstitial cells associated with the submuscular plexus of the guinea-pig colon.

Interstitial cells associated with the submuscular plexus of the guinea pig colon were studied by electron microscopy and by light microscopic wholemount stretch preparations. Their cytoplasmic features are similar to those of fibroblasts and they contain a well-developed Golgi apparatus, granular endoplasmic reticulum and many mitochondria. Intermediate filaments are abundantly distributed throughout the perinuclear region and processes. Numerous caveolae, a basal lamina and subsurface cisterns are observed on the cell membrane as in smooth muscle cells. The most characteristic feature of this cell type is the existence of many large gap junctions that interconnect these cells to each other and with the smooth muscle cells. Nerve varicosities containing synaptic vesicles are observed in close apposition with cells of this type. Whole-mount preparations stained by the zinc iodide-osmic acid method and by vimentin immunohistochemistry clearly demonstrated the stellate form of these gap junction-rich cells and suggested that they correspond to the interstitial cells of Cajal.

Animals↗
PubMed1996

Identification of the interstitial cells of Cajal.

Observation of whole mount stretch preparations using the zinc-iodide-osmic acid method reveals a wide variety of interstitial cells in different tissue layers of the guinea-pig small intestine. And a subsequent electron-microscopic examination and survey of references makes clear that the interstitial cells of Cajal (ICC) depicted in original drawings of Cajal are heterogeneous and correspond to different types of interstitial cells. The myenteric ICC are characterized by long dichotomous branching processes which constitute cellular networks independent from the nerve plexus and form many gap junctions at their tips. Their ultrastructure is similar to that of fibroblasts and they have no basal lamina. The myenteric ICC show strong immunoreactivity for vimentin and the c-kit receptor, and probably correspond to the intestinal pacemaker cells. Within the circular muscle layer, ICC are represented by the cells that are closely associated with fine nerve bundles. The ICC have various shapes, ranging from bipolar to stellate, depending on the running pattern of the nerve fibers that they are associated with. They show fibroblast-like ultrastructure and have no basal lamina. They form gap junctions with smooth muscle cells and are immunoreactive for vimentin. On the other hand, ICC associated with the deep muscular plexus described in the guinea-pig by Cajal could not be clearly identified. However, it is suggested that the ICC in this location may correspond to glycogen-rich cells possessing a basal lamina. Although they show a fairly well-developed rough endoplasmic reticulum, Golgi apparatus and immunoreactivity for vimentin, ICC of the deep muscular plexus are probably specialized smooth muscle cells in nature.

Animals↗
PubMed1996

[Examination of the degree of agreement among dental findings used for personal identification (report 5)--canonical correlation between dental findings on dental charts and those on radiographs].

Findings obtained from dental charts and from radiograph taken one year later for the same individuals were examined and classified according to different criteria. Similarities between the two sources investigated by the canonical correlation method. The results obtained were as follows: 1. The correlation coefficient and the squared multiple correlations (R2) were calculated. Consequently, high similarities were seen between the two sources for the mandibular anterior teeth [sequence: see text], maxillary incisor teeth [sequence: see text], mandibular and maxillary first premolar teeth [sequence: see text], and the corresponding teeth of the same jaws. 2. Three roots showed high elucidative values by the canonical correlation method. The first root was understood to be the mandibular incisor factor, the second the maxillary incisor factor, and the third the first premolar factor. This seemed to indicate, that the similarities between the two sources in these regions were very high. 3. A study of the similarities between the two sources was done based on the individual scores of canonical variable loadings calculated in this analysis. High similarities were seen at [sequence: see text] in category 1 (intact & C1) for chart findings and category 1'(intact, C1-C3 & resin filling) for radiographic findings: at [sequence: see text] in category 2 (C2-C4, inlay & filling of repair) for chart findings and category 3'(stump of tooth) for radiographic findings; and at [sequence: see text] in category 3 (complete crown, jacket crown & post crown) for chart findings and category 3'(stump of tooth) for radiographic findings. 4. The present results suggest that if proper case in taken, one set of information can serve as a substitute for the other. In personal identification, higher efficiency may be achieved if this is borne in mind.

Adult↗
PubMed1995

Fine structural study of interstitial cells associated with the deep muscular plexus of the rat small intestine, with special reference to the intestinal pacemaker cells.

Two types of interstitial cells have been demonstrated in close association in the deep muscular plexus of rat small intestine, by electron microscopy. Cells of the first type are characterized by a fibroblastic ultrastructure, i.e. a well-developed granular endoplasmic reticulum, Golgi apparatus and absence of the basal lamina. They form a few small gap junctions with the circular muscle cells and show close contact with axon terminals containing many synaptic vesicles. They may play a role in conducting electrical signals in the muscle tissue. Cells of the second type are characterized by many large gap junctions that interconnect with each other and with the circular muscle cells. Their cytoplasm is rich in cell organelles, including mitochondria, granular endoplasmic reticulum and Golgi apparatus. They show some resemblance to the smooth muscle cells and have an incomplete basal lamina, caveolae and subsurface cisterns. However, they do not contain an organized contractile apparatus, although many intermediate filaments are present in their processes. They also show close contacts with axon terminals containing synaptic vesicles. These gap-junction-rich cells may be regular components of the intestinal tract and may be involved in the pacemaking activity of intestinal movement.

Animals↗