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Biomedical subjects

E Nagata

Publications and source records attributed to E Nagata.

At least 19 recordsLinked to original sources
PubMed1992

Differences in the transport systems between cementocytes and osteocytes in rats using microperoxidase as a tracer.

Microperoxidase (MP) tracer was injected intravenously into rats to investigate any differences in transport pathways of tissue fluids in the lacunae and canaliculi of cementum and bone. Light microscopically, in deep cementum lacunae, pericellular spaces contained a large amount of MP, while close to the cementum surface, the spaces contained scarcely any. In bone, MP was detected throughout all pericellular spaces. MP was detected intracellularly as granular reaction products in most cementocytes and osteocytes. Electron microscopically, MP was found in the pericellular spaces of cementum and bone lacunae, particularly on collagen fibrils and amorphous material. MP deposits were also intense along the plasma membrane of cementocytes in the deep cementum and along the innermost edge of the deep cementum matrix and bone matrix. In uptake of MP by cementocytes, although extracellular tracer was deposited extensively along the plasma membrane of the deeply positioned cementocytes, uptake by these deep cementocytes was less than that of those close to the surface. However, in bone, most osteocytes showed uniform uptake. These results suggest that the transport pathways for tissue fluids in cementum are in the pericellular spaces, but that cementum has an uneven circulation of tissue fluid. In cementum, although there seems to be a well-developed canalicular system to transport tissue fluid into the deep regions, the deep cementocytes had less endocytotic ability than those close to the surface.

Animals↗
PubMed1992

Immunohistochemical study of nerve fibres with substance P- or calcitonin gene-related peptide-like immunoreactivity in the junctional epithelium of developing rats.

The beginning of innervation in the junctional epithelium of maxillary first molars was examined in gingival tissues from 19 to 32-day-old rats. Substance P- or calcitonin gene-related peptide (CGRP)-like immunoreactivity was demonstrated by the avidin-biotin peroxidase complex method. In 19-day-old rats, nerve fibres with substance P- or CGRP-like immunoreactivity were seen in the connective tissue and oral epithelium, but not in the reduced enamel epithelium, which would be transformed into the junctional epithelium. In 21-day-old rats, the fibres with substance P- or CGRP-like immunoreactivity formed a plexus in the oral sulcular epithelium and thin varicose fibres were seen for the first time entering the adjacent reduced enamel epithelium. These fibres also penetrated the middle portion of the reduced enamel epithelium, but did not reach the cuboidal reduced ameloblasts. More nerve fibres had CGRP-like immunoreactivity than substance P-like immunoreactivity. In 23-day-old rats, many fibres with both immunoreactivities were seen in the basal layers of the junctional epithelium, but only a few were seen in its superficial layers. In 28-32-day-old rats, numerous fibres with both immunoreactivities were distributed in the whole junctional epithelium and showed a similar pattern of innervation. For all immunoreactive fibres, the density in the middle portion in the junctional epithelium was the highest. The nerve plexus was formed in the basal layers and some fibres with a varicose appearance were found in the superficial layers.

Animals↗
PubMed1992

Alteration of second-messenger ligand binding following 2-hr hemispheric ischemia in the gerbil brain.

The alterations of second-messenger ligand binding and cerebral blood flow (CBF) were evaluated in the gerbil brain after 2-h unilateral common carotid artery occlusion. [3H]Forskolin (FK) and [3H]phorbol-12,13-dibutyrate (PDBu) were used as specific ligands for adenylate cyclase (AC) and protein kinase C (PKC) activity estimation, respectively. CBF was determined at the end of the experiment by the [14C]iodoantipyrine method. A quantitative autoradiographic method permitted simultaneous measurement of the three parameters in the same brain. The levels in the caudate-putamen, globus pallidus, and hippocampus were analyzed. The animals were divided into three groups: Group 1 with severe ischemia (CBF in the lateral nuclei of the thalamus (CBFt) less than 50 ml/100 g/min), Group 2 with mild ischemia (CBFt greater than or equal to 50 ml/100 g/min), and the Sham Group. The PDBu binding revealed a statistically significant increase in the caudate-putamen, lateral nuclei of the thalamus and hippocampus (CA1 and CA3 regions and dentate gyrus) on the ischemic side in Group 1 as compared to that in Group 2 and the Sham Group. In contrast, the FK binding did not show any significant changes in any of the regions. These data and our previous findings for 6-h ischemia suggest that (1) PKC translocation to the cell membrane may occur at the early ischemic phase in particular regions including the caudate-putamen, lateral nuclei of the thalamus and hippocampus, with the translocated PKC gradually diminishing during the subsequent ischemic period; and (2) the suppression of the AC system observed in 6-h ischemia may not appear in the early ischemic phase.

Adenylyl Cyclases↗
PubMed1992

A light and electron microscopic anterograde WGA-HRP tracing study on the sensory innervation of junctional and sulcular epithelium in the rat molar.

The sensory innervation of junctional and oral sulcular epithelium was investigated by use of anterograde transport of wheat-germ agglutinin-horseradish peroxidase from the trigeminal ganglion. By light microscopy, labeled intra-epithelial nerve fibers were observed forming a dense plexus in the apical two-thirds of the junctional epithelium, with some fibers located near the enamel space. Occasional fibers extended coronally to the sulcus bottom. By electron microscopy, labeled intra-epithelial axon terminals or varicosities were demonstrated to be in close contact with both junctional epithelial cells and neutrophils. These varicosities, which were occasionally surrounded by the cytoplasmic processes of epithelial cells or neutrophils, frequently contained large granular and small clear vesicles. In contrast to the junctional epithelium, the oral sulcular epithelium was sparsely innervated, except for the transition region between the oral sulcular epithelium and the junctional epithelium, where a dense innervation by labeled intraepithelial fibers was found. These fibers extended as far as the stratum spinosum. Electron microscopy revealed mitochondria-filled profiles of varicosities between epithelial cells. This study shows differences in the distribution and ultrastructure of sensory nerves between the junctional and oral sulcular epithelia, and further provides morphological evidence that sensory nerves in the junctional epithelium come into contact not only with epithelial cells but also with neutrophils.

Animals↗
PubMed1991

Inhibition of nitric oxide synthesis induces a significant reduction in local cerebral blood flow in the rat.

The effect of intravenous administration of NG-monomethyl-L-arginine (L-NMMA, 30 mg/kg), a specific inhibitor of nitric oxide synthesis, on local cerebral blood flow (lCBF) was examined in the rat using the [14C]iodoantipyrine autoradiographic method. L-NMMA induced a statistically significant reduction in lCBF in the cerebral cortices as well as in various deep structures of the brain. This reduction in lCBF was accompanied by a clear increase in mean arterial blood pressure, suggesting that the cerebral resistance vessels constricted significantly beyond the autoregulatory response following L-NMMA administration. These findings indicate that the basal cerebral circulation may be closely related to nitric oxide production.

Animals↗
PubMed1990

Formation of a stable L-ascorbic acid alpha-glucoside by mammalian alpha-glucosidase-catalyzed transglucosylation.

Enzymatic transglucosylation from maltose to L-ascorbic acid (AA) with mammalian tissue homogenates was determined by a high-performance liquid chromatography method and compared with the reaction catalyzed by alpha-glucosidase from Aspergillus niger. The homogenates of small intestine and kidney had a high transglucosylase activity to form a new type of glucosylated AA, which was associated with alpha-glucosidase activity. The new compound was demonstrated to be an equimolar conjugate of AA and glucose by the spectral and quantitative analyses. In particular, it showed a high stability in a neutral solution and no reducing activity toward cytochrome c and a dye. These properties were very different from those of AA and L-ascorbic acid alpha-glucoside formed with alpha-glucosidase from A. niger, but they were consistent with those of L-ascorbic acid 2-O-phosphate and L-ascorbic acid 2-O-sulfate. Moreover, it exhibited a reducing power associated with AA after mild acid hydrolysis or treatment with rat intestinal alpha-glucosidase. These results indicate that it should be assigned the 2-O-alpha-glucoside structure. Consequently, it is concluded that mammalian alpha-glucosidase is able to form a very stable and nonreducing form of glucosylated AA through a specific transglucosylation reaction distinct from that of microbial alpha-glucosidase.

Animals↗
PubMed1987

An ovarian cancer-associated antigen that crossreacts with a pregnancy-associated protein.

The presence of an ovarian ascitic antigen that crossreacts with a placental antigen was demonstrated in ascitic fluid from patients with advanced ovarian cancer, and the antigen was partially purified. Immunodiffusion and immunoelectrophoresis were employed to confirm the existence of the reactive antigen and to determine the relationships between the antigens from various sources. On double immunodiffusion, the ovarian ascitic antigen was found to be immunologically completely identical with a placental antigen against monospecific antisera raised against an ovarian ascitic and a placental antigen, respectively. On gel filtration on Sephadex G-200, the antigenic activity was eluted in two regions corresponding to different molecular sizes. The two preparations of the larger and smaller forms showed complete identity on double immunodiffusion, but dissimilar mobilities on immunoelectrophoresis. Preliminary characterization of the antigen revealed that it is distinct from several cancer-related antigens so far described.

Antigens, Neoplasm↗
PubMed1986

Polysomnography--functional topographical examination of the basal ganglia.

Polysomnographical examinations were performed on two cases with unilateral lesion in the basal ganglia. One (case 1) was a 10-year-old girl with tuberous sclerosis with subependymal nodules on the left thalamostriatal sulcus and rotatory seizures, and pharmacologically the existence of a postsynaptic supersensitivity of the dopaminergic (DA) neurons, was suggested. The other (case 2) was an 8-year-old boy with infarction of the left putamen. Two types of body movements (BMs); gross movements (GM) and twitch movements (TM), were evaluated. The mode of occurrence of these BMs against each sleep stage, the pattern of BMs, and the ratio of the number of TM in the mentalis muscle in stage REM against the number of rapid eye movements (REMs) (ment TM REM/REMs) were estimated. The modulation of these parameters by L-Dopa and pimozide was studied. The pattern of GM reflected the DA activity of the side of the lesion. TM of the contralateral side reflected the pathophysiology of the lesion. TM of the ipsilateral extremities of case 1 showed the pattern of DA hyperactivity, which were reduced by small doses of L-Dopa. In case 2, TM of the ipsilateral extremities showed a normal pattern and rate, which increased markedly after L-Dopa. The TM of the sternocleidomastoideus revealed abnormal ipsilaterally in case 1 and contralaterally in case 2. The ment TM REM/REMs ratio reflected the real function of the DA neurons and did not reflect their hyperfunction due to postsynaptic supersensitivity. The numbers and direction of REMs might reflect the function of the basal ganglia, particularly of the DA neurons.

Basal Ganglia↗
PubMed1986

A case of intraluminal duodenal diverticulum associated with congenital biliary dilatation: a review of the literature in Japan.

A case of intraluminal duodenal diverticulum (IDD) associated with congenital biliary dilatation is reported. Patients with intraluminal duodenal diverticulum often have congenital anatomical abnormalities or acquired diseases. The treatment of the intraluminal duodenal diverticulum itself is easy, but it is important to detect and treat other disorders also present.

Biliary Tract↗
PubMed1985

Spectrophotometric studies on alkaline isomerization of spinach ferredoxin.

The gross protein structure, the microenvironment of the iron-sulfur cluster, and the effect of neutral salts on the molecular structure of spinach ferredoxin were studied by CD and absorption spectroscopy in the alkaline pH range. In the pH range of 7-11, the existence of reversible isomerization which consisted of at least two proton dissociation processes was indicated by the statical CD and absorption spectra. The CD changes in the visible and far-UV regions were dramatic upon elevation of the pH from neutral to alkaline, indicating a significant alteration of the microenvironment of the cluster and a decrease in the ordered secondary structures. The absorption change in the visible region due to pH elevation was small but clearly observed with a high signal-to-noise ratio. The numbers of protons involved in the respective processes and the apparent pK values obtained from the pH-dependence of the CD changes were in good agreement with those obtained from the pH-dependence of the absorption changes in the visible region. In addition, the rate constants obtained from the time courses of the CD and absorption changes agreed with one another. By the addition of 1 M NaCl, the CD and absorption spectra at alkaline pH were reversed almost to those at neutral pH without significant pH change. On the other hand, above pH 11, ferredoxin was found to be irreversibly denatured. Based on analyses of the statical CD and absorption spectra and of the time courses of the CD changes, the probable mechanism of the isomerization was considered to be as follows: (Formula: see text) where H stands for a proton, N-form for native ferredoxin at neutral pH, N*-form for alkaline ferredoxin below pH 11 which still has the iron-sulfur cluster but with disordered secondary structures of the polypeptide chain, and D-form for completely denatured ferredoxin above pH 11. These results lead to the conclusions that (1) the interaction between the protein moiety and the iron-sulfur cluster is essential for maintaining the native ferredoxin structure, and (2) neutral salts protect the polypeptide chain from unfolding through electrostatic interaction with the ionized side chains, resulting in the stabilization of ferredoxin.

Circular Dichroism↗
PubMed1985

The relation between carcinoma of the gallbladder and an anomalous connection between the choledochus and the pancreatic duct.

An anomalous connection between the choledochus and the pancreatic duct may be associated etiologically or pathogenetically with congenital biliary dilation and carcinoma of the dilated bile duct. During the past 10 years, a total of 14 cases of carcinoma of the gallbladder with an anomalous connection between the choledochus and the pancreatic duct were encountered. These cases were studied in reference to their clinical features and histological findings. An experimental model of pancreatic juice inflow into the gallbladder of mongrel dogs was produced and the histological changes of the mucosa of that organ was observed. The intent was to elucidate the relationship between carcinoma of the gallbladder and this anomaly. The results of this clinical and experimental study suggest that reflux and stasis of pancreatic juice in the gallbladder induce chronic cholecystitis with intestinal metaplasia. This may be important in the pathogenesis of well-differentiated carcinoma of the gallbladder.

Adenocarcinoma↗
PubMed1985

[Hepatectomy after transcatheter arterial embolization (TAE) for hepatocellular carcinomas].

Subjects of this study were 26 patients with hepatocellular carcinoma who underwent hepatectomy after TAE. They did not develop serious complications due to TAE. A suitable interval between TAE and the planned hepatectomy was about one month, based on AFP levels and the recovery of liver functions. Hepatic arteriography after TAE was useful to observe changes of the blood flow into the liver and the carcinoma, as well as to find intrahepatic metastases. It is also necessary for making final decisions on the strategy of the hepatectomy. The effects of TAE greatly depended on patterns of arterial blood feeding. When the tumor was less than 5 cm in diameter, had a capsule, and was fed by a single artery the necrotic rate was high. TAE was effective in intrahepatic metastases 0.5 cm or more in diameter, which were detectable by hepatic arteriography. TAE had little effect on intrahepatic metastases less than 0.5 cm in diameter, on intracapsular or extracapsular invasion, or on tumor embolus. For tumor embolus in the portal vein, since TAE and hepatectomy give poor results, other methods should be considered.

Adult↗