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Biomedical subjects

H Inokuchi

Publications and source records attributed to H Inokuchi.

At least 181 records · Page 10Linked to original sources
PubMed1983

Cellular kinetics of gastrointestinal mucosa, with special reference to gut endocrine cells.

After 3H-thymidine autoradiography was introduced to the study of cellular kinetics, the epithelial cells of the gastrointestinal mucosa have been examined extensively with regard to their kinetic behavior. After reviewing the knowledge on the kinetics of different epithelial cells in the stomach and small and large intestine, this article concentrates on the origin, differentiation and turnover of gut endocrine cells which have been under much controversy. Autoradiographic and other investigations of EC cells support the view that these cells are not neuroectodermal in origin, but differentiate from an immature type of gut epithelial cells. We investigated the kinetics of the antral G cells in the hamster, G cells and S cells in the rat duodenum by the combined utilization of 3H-thymidine autoradiography with immunohistochemistry, and confirmed that these cells are derived from the same precursor cells as the other mucosal cells of the gastrointestinal tract. The half-life of the antral G cells was estimated at 10-15 days, while the turnover time of the G cells and S cells in the duodenum were calculated at 3-4 days and 2 days, respectively. These data also support the belief that gut endocrine cells originate from the endoderm. Histopathological alterations such as antral gastritis and intestinal metaplasia, as well as vagal denervation, were shown to influence the population of the antral G cells in man and the hamster. This supports the view that intrinsic and extrinsic stimuli might alter the kinetics of gut endocrine cells.

Animals↗
PubMed1983

Neural regulation of pancreatic polypeptide release.

To clarify the nervous system's role in the regulation of pancreatic polypeptide (PP) release, extrinsic innervation to the in situ pancreas was eliminated in five dogs. Before and 2 weeks after denervation, PP was measured during insulin hypoglycemia and ingestion of a protein meal. Exogenous insulin caused a similar marked hypoglycemia in both control and denervated dogs. Hypoglycemia caused a significant increase in plasma PP in control dogs from a baseline of 42 +/- 8 pg/ml to 86 +/- 18 pg/ml at 20 minutes (P less than 0.01). In denervated dogs plasma PP did not increase with hypoglycemia, and levels were significantly less than in the control animals at 30 and 60 minutes (P less than 0.05). With a protein meal, PP increased in the control animals from 53 +/- 12 to 116 +/- 16 pg/ml at 10 minutes (P less than 0.05), 164 +/- 22 pg/ml at 20 minutes (P less than 0.05), and 193 +/- 20 pg/ml at 60 minutes (P less than 0.01). Denervation markedly blunted this response, and PP increased only from 53 +/- 6 to 64 +/- 4 pg/ml at 10 minutes, to 83 +/- 12 pg/ml at 20 minutes, and to 91 +/- 8 pg/ml at 60 minutes. PP became significantly elevated above baseline in denervated dogs only at 60 minutes (P less than 0.05), and PP was significantly lower than in the control group at 10, 20, and 60 minutes after the meal (P less than 0.05). Immunostaining for insulin, glucagon, somatostatin, and PP showed no difference in the number and distribution of these endocrine cells in predenervation and postdenervation specimens. Adrenergic and cholinergic nerves were seen in all control specimens but, except for a few adrenergic fibers, were not seen in denervated animals. Peptidergic nerves that contained vasoactive intestinal polypeptide (VIP) were seen in all areas of the pancreas before and after denervation. This study confirms that the initial rise in PP with a protein meal is governed by vagal cholinergic pathways. Later postprandial PP secretion is controlled by an interplay between these cholinergic pathways and other uncertain influences such as hormonal or substrate changes. The pancreas has a rich intrinsic peptidergic system of VIP-containing nerves.

Animals↗
PubMed1982

Escherichia coli glutaminyl-tRNA synthetase. I. Isolation and DNA sequence of the glnS gene.

We have isolated a lambda-transducing phage carrying the gene (glnS) for Escherichia coli glutaminyl-tRNA synthetase. The location of the glnS gene within the 13.5-kilobase E. coli DNA transducing fragment was determined by genetic means. The glnS gene was recloned into plasmid pBR322 and its nucleotide sequence was established. The DNA sequence translates to a protein of 550 amino acids.

Amino Acyl-tRNA Synthetases↗
PubMed1982

Immunohistochemical demonstration of EC cells in rat gastrointestinal tract.

Selective immunohistochemical demonstration of enterochromaffin (EC) cells in the rat gastrointestinal tract has been carried out, using a highly specific rabbit antiserotonin (5-HT) serum and the unlabeled peroxidase-antiperoxidase complex (PAP) technique. The daily profile of the EC cell density was also studied using this method. No significant change was recorded.

Animals↗
PubMed1981

The effects of neuroleptics on the GABA receptor of cat primary afferent neurons.

Butyrophenones (haloperidol and pimozide) at low concentrations (0.05-1.0 micro M) inhibited the GABA-induced depolarization of cat primary afferent neurons, while at high concentrations (greater than 10 micro M) they enhanced the GABA-depolarization. These actions of the butyrophenones were not accompanied by any measurable change in the dissociation constant of the GABA-GABA receptor interaction, whereas their inhibitory and facilitatory influences on the GABA-depolarization were associated with reduction and increase in the cell membrane resistance, respectively. Further analysis showed that the reduction of membrane resistance by low concentrations of butyrophenones was brought about by an increased sodium and potassium conductance and that the increase in membrane resistance by a high concentration of these drugs was caused by a reduced sodium and potassium conductance. In contrast to the butyrophenones, a typical phenothiazine derivative (chlorpromazine) at concentrations of 0.1-100 micro M did not affect the GABA-depolarization. The results suggest that butyrophenones do not mimic the action of GABA as originally proposed by Janssen, but alter the GABA-induced depolarization indirectly by modifying the electrically excitable portion of the cell membrane. Chlorpromazine, a phenothiazine, on the other hand, has no recognizable effects on either the GABA-receptor membrane or the electrically excitable membrane.

Afferent Pathways↗
PubMed1981

Electrocatalytic four-electron reduction of oxygen at the cytochrome c3-adsorbed electrode.

The electrocatalytic activity of cytochrome c3 for the reduction of molecular oxygen was characterized from the studies of the adsorption of cytochrome c3 and the co-adsorption of cytochrome cs with cytochrome c on the mercury electrode by the a.c. polarographic technique. The adsorption of cytochrome c3 on the mercury electrode is irreversible and is diffusion-controlled. The maximum amount of cytochrome c3 absorbed was 0.92 . 10(-11) mol . cm-2 at -0.90 V. The amount of cytochrome c3 in the mixed adsorbed layer with cytochrome c was determined from the differential capacitance measurement. It was shown that the fractional coverage of cytochrome c3 can be estimated from its bulk concentration and the diffusion coefficient (1.05 . 10(-6) cm2 . s-1). Cytochrome c3 catalyzes the electrochemical reduction of molecular oxygen from the two-electron pathways via hydrogen peroxide to the four-electron pathway at the mercury electrode in neutral phosphate buffer solution. The catalytic activity varies with the bulk concentration of cytochrome c3. The highest catalytic activity for the oxygen reduction (no hydrogen peroxide formation) is attained when one-half of the mercury electrode surface is covered by cytochrome c3. The addition of cytochrome c or bovine serum albumin to the cytochrome c3 solution inhibits the catalytic activity of cytochrome c3. The reversible polarographic behavior of cytochrome c3 through the mixed adsorbed layer of cytochrome c3 and cytochrome c was also investigated.

Adsorption↗
PubMed1981

The structure of cytochrome c3 from Desulfovibrio vulgaris Miyazaki at 2.5 A resolution.

The structure of tetraheme cytochrome c3 isolated from Desulfovibrio vulgaris Miyazaki has been determined at 2.5 A resolution by an X-ray diffraction method. Protein phases were computed by the multiple isomorphous replacement method using the native and four heavy atom derivatives, anomalous scattering measurements of the latter being considered. The mean figure of merit was 0.77. Four heme groups are exposed on the surface of the molecule. There are some short helical segments in the polypeptide chain, and hair-pin turns are often observed at glycine and alanine residues.

Amino Acid Sequence↗
PubMed1980

Dopamine depolarisation of mammalian primary afferent neurones.

Dopamine (DA) is an important neurotransmitter or neuromodulator in the mammalian nervous system. As such, it is implicated in the aetiology and therapy of various disease conditions--for example, Parkinson's disease, schizophrenia, Huntington's disease and tardive dyskinesia. However, only limited electrophysiological information is presently available concerning dopamine receptors in the mammalian nervous system, and there are only three reports in which intracellular techniques have successfully recorded the action of DA on individual central neurones. In all cases, DA depolarised the respective neurones. In the periphery, DA is reported to hyperpolarise superior cervical ganglia. However, this hyperpolarisation has been shown to be due to activation of alpha-adrenoreceptors and not to a response of DA on a DA receptor. Peripheral DA actions have also been described presynaptically, but are difficult to study electrophysiologically for technical reasons. As a result, little is known at the membrane level about the effects of drugs thought to modulate or interact with DA receptors. In the present report, we describe a depolarising action for DA on the cat dorsal root ganglion.

Afferent Pathways↗
PubMed1980

Genes and sites involved in replication and incompatibility of an R100 plasmid derivative based on nucleotide sequence analysis.

The nucleotide sequence of the entire region required for autonomous replication and incompatibility of an R100 plasmid derivative, pSM1, has been determined. This region includes the replication region and all plasmid encoded information required for replication. Numerous reading frames for possible proteins can be found in this region. The existence of one of these proteins called RepA1 (285 amino acids; 33,000 daltons) which is encoded within the region known by cloning analysis to be required for replication is supported by several lines of evidence. These include an examination of the characteristic sequences on the proximal and distal ends of the coding region, a comparison of the sequence of the replication regions of pSM1 and the highly related R1 plasmid derivative Rsc13 as well as other biochemical and genetic evidence. The existence of two other proteins, RepA3 (64 amino acis; 7000 daltons) and RepA2 (103 amino acids; 11,400 daltons) is also consistent with most of the criteria mentioned above. However, the region encoding RepA3, which by cloning analysis is within the region responsible for both replication and incompatibility, has never been demonstrated to produce a 7,000 dalton polypeptide. Since a large secondary structure can be constructed in this region, it is possible that the region contains structure or other information that is responsible for incompatibility. RepA2, encoded entirely within the region identified by cloning analysis to be responsible for incompatibility but not for replication can be visualized in vivo and in vitro. However, the nucleotide sequence of the region encoding RepA2 is completely different in mutually incompatible plasmid derivatives of R1 and R100. It is therefore unlikely that RepA2 plays a major role in incompatibility. Thus, we predict that RepA2 is required to initiate DNA synthesis at the replication origin and that the region proximal to RepA2 either encodes a gene product or structure information that is responsible for incompatibility.

Base Sequence↗
PubMed1980

G-cell population and serum gastrin response to cimetidine-OXO test meal in relation to histopathological alterations in resected stomachs from patients with peptic ulcer disease.

The relationship between histopathological alterations and G-cell population in the stomach was studied in l4 resected stomachs from patients with chronic peptic ulcer disease (6 with duodenal ulcer and 8 with gastric ulcer). G-cells were identified by indirect immunoperoxidase method. When atrophy was graded three steps (0, 1, 2), the average grade of DU and GU was 0.23 and 0.89, respectively. There was a significant correlation (r=0.871, p less than 0.005) between atropic grade and G-cell population in each stomach. The mean occupation rate with intestinal metaplasia was 0.9% in DU and 35.8% in GU. There was no correlation between total pyloric area and G-cell population, however residual pyloric area excluding intestinal metaplasia correlated significantly with G-cell population (r=0.557, p less than 0.05). There was a significant difference in the mean G-cell population which were 26.5 millions in DU and 8.9 millions in GU. The mean integrated gastrin response to Cimetidine-OXO test meal were 559+/-236 pg/ml in DU and 216+/-124 pg/ml in GU, and there was significant correlation (r=0.889, p less than 0.005) between G-cell population and integrated gastrin response. The average age of both groups, however, was 27.7 in DU and 52.8 in GU, so that these differences of G-cell population and functional G-cell mass in both groups might originate in the histopathological alterations accompanying with the aging.

Adolescent↗
PubMed1980

Application of Mössbauer spectroscopy to wet bacterial cells.

Although Mössbauer spectroscopy has been applied only to samples in the dry or frozen state, we present evidence showing that this spectroscopy is applicable to biological iron compounds in the wet state if they are tightly bound to the cell membrane or cell wall.

Cell Membrane↗