Biomedical subjects

K Inoue

Publications and source records attributed to K Inoue.

At least 19 recordsLinked to original sources

PubMed1992

Parasympathetic postganglionic nerve fibers in the fungiform papillae of the bullfrog, Rana catesbeiana.

An investigation was made of the precise origin of the unmyelinated nerve fibers in the fungiform papillae of the bullfrog's tongue. Some unmyelinated nerve fibers in the fungiform papillae originate from the parasympathetic postganglionic cells in the glossopharyngeal nerve. Axonal enlargements of the parasympathetic nerve fibers were in close contact with the Merkel-like basal or supporting cells in the taste disk. These results seem to provide morphological evidence for the existence of an efferent control system in the taste disk.

Animals↗

PubMed1992

Control of Drosophila Sex-lethal pre-mRNA splicing by its own female-specific product.

Drosophila melanogaster somatic sexual differentiation is accomplished by serial function of the products of sex-determination genes. Sex-lethal (Sxl), is one such gene. It is functionally expressed only in female flies. The sex-specific expression of this gene is regulated by alternative mRNA splicing which results in either the inclusion or exclusion of the translation stop codon containing third exon. Although previous genetic and molecular analyses suggest that functional Sxl expression is maintained by a positive feedback loop, where the female-specific Sxl product promotes the synthesis of its own female-specific mRNA, the mechanistic details of such regulation have remained unclear. We have developed a cotransfection system using Drosophila cultured (Kc) cells in which Sxl primary transcripts are expressed with or without the female specific Sxl product. Here we show that the female-specific Sxl product induces the synthesis of its own female-specific mRNA by negative control of male-specific splicing. Deletion, substitution, and binding experiments have demonstrated that multiple uridine-rich sequences in the introns around the male-specific third exon are involved in the splicing regulation of Sxl pre-mRNA.

Animals↗

PubMed1992

Release of 14-kDa group-II phospholipase A2 from activated mast cells and its possible involvement in the regulation of the degranulation process.

Group II phospholipase A2 was detected in appreciable amounts in rat peritoneal mast cells. The effect of several inhibitors specific to 14-kDa group-II phospholipase A2, including two proteinaceous inhibitors and a product of microorganisms with a low molecular mass, on mast-cell activation was examined. When rat peritoneal mast cells were sensitized with IgE and then challenged with antigen, the specific phospholipase-A2 inhibitors suppressed histamine release in a concentration-dependent manner. By contrast, these inhibitors showed no effect on prostaglandin generation under the same conditions. Histamine release from rat peritoneal mast cells subjected to non-immunochemical stimuli, such as concanavalin A, the Ca2+ ionophore A23187, compound 48/80 and substance P was also suppressed. When rat peritoneal mast cells were treated with 14-kDa-group-II-phospholipase-A2-specific inhibitors, washed and stimulated, histamine release was not affected appreciably. Similar suppressive effects of the inhibitors on histamine release were observed with mouse cultured bone-marrow-derived mast cells. When bone-marrow-derived mast cells were activated, they secreted both a soluble and an ecto-enzyme form of 14-kDa group-II phospholipase A2, although appearance of the enzyme associated with the external surface of cells was observed transiently. An appreciable amount of membrane phospholipids was degraded during activation of mast cells, which was decreased by treatment with 14-kDa-group-II-phospholipase-A2 inhibitor. These observations suggest that degranulation and eicosanoid generation in mast cells are regulated independently by discrete phospholipases A2 and that the 14-kDa group-II phospholipase A2 released from mast cells during activation may play an essential role in the progression of the degranulation process.

Animals↗

PubMed1992

Inhibitory effect of activated protein C on platelet aggregation induced by the prothrombin-converting reaction.

The present study was undertaken to elucidate the effect on platelet aggregation of the prothrombin-converting reaction on platelets with or without activated protein C (APC). A reaction mixture of washed platelets from human individuals, Factor Xa and prothrombin markedly induced platelet aggregation; maximum aggregation rates, 31.3-92.5%, and times to reach to maximum aggregation, 11.6 to 20.1 min. This aggregation was inhibited by the addition of APC with 50% inhibition concentration (IC50) value of 14.4 U/ml. APC also inhibited thrombin generation in the reaction mixture in a dose-dependent manner with IC50 value of 0.96 U/ml. However, APC did not inhibit the thrombin (0.1 CU/ml)-induced platelet aggregation at concentrations of up to 30 U/ml. These findings suggest that APC has no direct inhibitory effect on platelet aggregation and that APC inhibits platelet aggregation through inhibition of thrombin generation.

Blood Platelets↗

PubMed1992

Binding of the Drosophila transformer and transformer-2 proteins to the regulatory elements of doublesex primary transcript for sex-specific RNA processing.

Sex-specific alternative processing of double-sex (dsx) precursor messenger RNA (pre-mRNA) is one of the key steps that regulates somatic sexual differentiation in Drosophila melanogaster. By transfection analyses using dsx minigene constructs, we identified six copies of the 13-nucleotide sequences TC(T/A)(T/A)C(A/G)ATCAACA in the female-specific fourth exon that act as the cis elements for the female-specific splicing of dsx pre-mRNA. UV-crosslinking experiments revealed that both female-specific transformer (tra) and transformer-2 (tra-2) products bind to the 13-nucleotide sequences of dsx pre-mRNA. These results strongly suggest that the female-specific splicing of dsx pre-mRNA is activated by binding of these proteins to the 13-nucleotide sequences.

Animals↗

PubMed1992

Correlation between nucleolar organizer regions visualized by silver staining and the growth rate in lung adenocarcinoma.

BACKGROUND: The value of nucleolar organizer regions (NOR) visualized by silver staining (AgNOR) for the histologic differentiation, pathologic staging, and estimation of growth rate was assessed by the investigation of paraffin sections from 58 lung adenocarcinomas. AgNOR consist of NOR-associated proteins, and the number of AgNOR might be related to proliferative activity. METHODS: In lung adenocarcinoma, the growth rate can be measured by means of chest radiographs. Using this technique, the authors studied the correlation between the mean number of AgNOR and growth rate. RESULTS: The mean number of AgNOR ranged from 1.8 to 6.3 (mean +/- standard deviation, 4.0 +/- 0.8). Neither the degree of histologic differentiation nor the pathologic staging was related to the AgNOR count. The tumor growth rate was estimated on the basis of the doubling time in the chest radiographs of 13 patients. The doubling time ranged from 80 to 760 days. There was a high inverse correlation between the AgNOR count and the doubling time (r = -0.910; P less than 0.001). CONCLUSIONS: Thus, it appears to be possible to use the mean number of AgNOR as an index of proliferative activity.

Adenocarcinoma↗

PubMed1992

Expression of epidermal growth factor receptor after partial pancreatectomy in adult rats: an immunohistochemical study.

The expression and localization of epidermal growth factor (EGF) were investigated immunohistochemically using an anti-EGF receptor antibody in the pancreas of partial pancreatectomized and sham-operated adult rats. In the sham-operated pancreas, immunoreactive products against EGF receptor were only slightly positive in the pancreatic acinar cells. In the partial pancreatectomized pancreas on the fifth day after operation, EGF receptor immunoreactivity was intensely positive in the acinar cells, in some cells lining the intercalated ducts and some basal cells of the acinus, but it was not detected in the pancreas when exogenous EGF was given to the rat after partial pancreatectomy for three days. The present results suggest that EGF receptor is expressed in the regenerating pancreatic tissue, and EGF could be involved in the mechanism of pancreatic regeneration in rats.

Animals↗

PubMed1992

Metal-inducible activities of metallothionein promoters in fish cells and fry.

Activities of trout metallothionein-A promoter and mouse metallothionein-I promoter in fish cells and fry were examined using the chloramphenicol acetyltransferase (CAT) gene as a reporter. Transfection and transient CAT assays on a trout liver cell line indicated that both promoters were inducible by metals, including zinc. In vivo activities of both promoters were examined using microinjection system into medaka eggs. Some of the hatched fry were exposed to zinc and their CAT activities were assayed. Both promoters revealed considerable activities after exposure to zinc while only weak activities were detected in unexposed fry.

Animals↗

PubMed1992

Dopamine receptor agonists and antagonists enhance ATP-activated currents.

The effects of dopamine and related compounds on ATP-activated channels were investigated in pheochromocytoma PC12 cells. Dopamine (10 microM) enhanced an inward current activated by 100 microM ATP. A similar enhancement of the ATP-activated current was observed with apomorphine (10 microM), a non-selective dopamine receptor agonist, with (+)-SKF-38393 (10 microM), a selective dopamine D1 receptor agonist, and with (-)-quinpirole (10 microM), a selective dopamine D2 receptor agonist. Moreover, (+)-SCH-23390 (30 microM), a dopamine D1 receptor antagonist, and (-)-sulpiride (30 microM), a dopamine D2 receptor antagonist, also enhanced the ATP-activated current. The results suggest that ATP-activated channels are modulated by dopaminergic mechanisms, and that this modulation cannot be attributed to any single class of dopamine receptors.

Adenosine Triphosphate↗

PubMed1992

Immunohistochemical study on epidermal growth factor (EGF) receptor during carcinogenesis in the rat liver.

The expression and localization of epidermal growth factor (EGF) receptor were investigated immunohistochemically using anti-EGF receptor antibody in the normal rat liver and 3'-methyl-4-dimethylaminoazobenzen (3'-Me-DAB) induced tumors in rats. In 8 weeks after 3'-Me-DAB treatment, multiple nodules of cholangiocarcinoma were found in the rat liver, and atypical nodules of hepatocytes were also found 14 weeks later. Immunoreactive products against EGF receptor were only slightly positive in the normal liver, the nodule of cholangiocarcinoma, and atypical nodule of hepatocytes. It was noted that EGF receptor immunoreactivity was more intense in non-cancerous tissue adjacent to tumorous nodules than in the cancerous tissue. The present finding suggests that the expression of EGF receptor may be associated with regenerating as well as carcinogenetic processes in the rat liver.

Adenoma, Bile Duct↗

PubMed1992

Covalent binding of C3b to C4b within the classical complement pathway C5 convertase. Determination of amino acid residues involved in ester linkage formation.

C5 convertase of the classical complement pathway is a protein complex consisting of C4b, C2a, and C3b. Within this complex C3b binds to C4b via an ester linkage. We now present evidence that the covalent C3b-binding site on human C4b is Ser at position 1217 of C4. We also show that formation of the covalently linked C4b.C3b complex occurs in the mouse complement system and that the C3b-binding site on mouse C4b is Ser at position 1213 which is homologous to Ser-1217 of human C4. Therefore, covalent binding of C3b to a single specific site on C4b within the classical pathway C5 convertase is likely a common phenomenon in the mammalian complement system. Specific noncovalent association of metastable C3b with C4b would occur first, leading to reaction of the thioester with a specific hydroxy group. This is supported by two lines of experimental evidence, one which shows that a mutant C4 that does not make a covalent linkage with C3b is still capable of forming C5 convertase and a second in which the C4b.C3b complex has been demonstrated by cross-linking erythrocytes bearing this C5 convertase.

Amino Acid Sequence↗

PubMed1992

Change in phospholipid composition of mouse bone marrow-derived mast cells during cultivation with fibroblasts.

A mouse bone marrow-derived mast cell (BMMC) clone, designated as MC-MKM, was established. MC-MKM cells released histamine and generated lipid chemical mediators such as prostaglandin D2 or platelet-activating factor upon stimulation with IgE and antigen. It is known that BMMCs acquired the characteristics of connective tissue mast cells (CTMCs) during coculture with fibroblasts. In the present study, we found that cellular phospholipid composition changed drastically when MC-MKM cells were cultured for 2 weeks in the presence of mouse 3T3 fibroblasts. In MC-MKM cells, phosphatidylcholine was the predominant phospholipid class, followed by phosphatidylethanolamine. During coculture with fibroblasts for 2 weeks, total phospholipid content in MC-MKM cells increased 2.5-fold. Among major phospholipid classes, a percentage of phosphatidylethanolamine increased most dramatically in accordance with a decrease in that of phosphatidylcholine, while no appreciable change in composition of other phospholipids was observed. The phospholipid composition of cocultured MC-MKM cells was closer to that of rat peritoneal CTMCs than that of the starting MC-MKM cells. The present findings that BMMCs converted their phenotype into CTMC-like cells by the interaction with fibroblasts in terms of phospholipid composition are not contradictory to the previous observations that BMMCs changed into CTMC-like cells.

3T3 Cells↗

PubMed1992

Role of TraT protein, an anticomplementary protein produced in Escherichia coli by R100 factor, in serum resistance.

Escherichia coli K12 strain W3110/SM bearing a plasmid containing the traT gene (traT+ strain) was more resistant to the bactericidal activity of guinea pig serum than the same strain bearing this plasmid without the traT gene (traT- strain). A murine mAb was generated against synthetic TraT peptide (86-99). This antibody reacted only with denatured TraT protein, but it was used for monitoring TraT protein by immunoblotting during purification of the protein. Six mAb were then generated against partially purified traT protein from the solubilized membrane fraction of the traT+ strain. These mAb reacted with the native protein even on living cells, and their F(ab) fragments were found to suppress the inhibitory effect of the TraT protein on the bactericidal activity of serum. TraT protein was purified from solubilized membranes of the traT+ strain by ion exchange and gel filtration chromatographies. The purified TraT protein inhibited the lysis of sensitized erythrocytes by serum complement. Its inhibitory action was mainly on the C6 step. It strongly inhibited the reaction of C6 with EAC14b2a3b and excess C5, C7, C8, and C9. TraT protein also inhibited the reaction of C7-deficient human serum with guinea pig erythrocytes when it was activated by cobra venom factor. It did not inhibit the reaction of preformed C5b6 complexes. However, TraT did not have any effect on the cleavage of 125I[C5] to 125I[C5b] in similar conditions. It also partially inhibited the reaction steps of C4, C5, and factor B and limited guinea pig complement serum in 0.1% gelatin veronal buffered saline, pH 7.4, containing 10 mM EDTA with their respective preceding intermediate cells. It had no effect on either the binding of C3 to EAC14b2a or the cleavage of C3b by factors H and I. TraT protein probably inhibits the formation of C5b6 complex or causes structural alteration of the complex to a nonfunctional form.

Amino Acid Sequence↗

PubMed1992

Bactericidal activity of C9-deficient human serum.

Escherichia coli B/SM, strain 1-1, was killed dose dependently by human hereditary C9-deficient serum (C9DHS), which was shown to contain no C9 Ag by an ELISA method. On the other hand, human hereditary C7-deficient serum did not kill the bacteria under similar conditions. The bactericidal activity of C9DHS was inhibited by rabbit anti-C5 antibody but not by murine anti-C9 mAb. The anti-C9 antibody decreased the bactericidal activity of normal human serum (NHS) to the level of that with C9DHS. Sheep anti-human lysozyme antibody did not affect the bactericidal activity of C9DHS or NHS even when added at more than twice the concentration required to block the serum lysozyme activity on Micrococcus luteus. After treatment with C9DHS and washing, surviving Escherichia coli were killed by C9, but not by lysozyme, transferrin, or both. Other strains of E. coli (K12 W3110, C600, and NIHJ) and Salmonella typhimurium (strain NCTC 74), all maintained in the laboratory, were also killed by C9DHS. However, pathogenic strains recently isolated from patients with traveler's diarrhea and some strains of S. typhimurium were resistant to both C9DHS and NHS, at least at the serum concentration tested. A concentration of 0.1 M Tris did not increase the susceptibility of serum-resistant strains of bacteria to C9DHS, but made one strain of S. typhimurium tested susceptible to NHS, but not to C9DHS. These results clearly showed that C9DHS kills bacteria that are sensitive to NHS through activation of C up to the step of C8 in the same way that C9-deficient C serum lyzed sensitized erythrocytes.

Blood Bactericidal Activity↗

PubMed1992

Extracellular adenosine 5'-triphosphate-evoked glutamate release in cultured hippocampal neurons.

Characteristics of extracellular ATP-evoked electrical responses in rat hippocampal neurons were investigated. Extracellular ATP (100 microM) induced a rapid depolarization followed by repetitive firings of spikes in these cells under whole-cell current-clamp. In whole-cell voltage-clamp experiments, ATP activated 2 types of inward currents that were inhibited by P2-purinoceptor blocker suramin (300 microM). One is a small (about -20 pA) sustained current which is insensitive to tetrodotoxin (TTX), and the other is a large (-100 to -300 pA) transient current which abolished in the presence of 3 microM TTX. The ATP-induced transient current was blocked by 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX; 30 microM), a non-N-methyl-D-aspartate (non-NMDA) receptor antagonist. ATP failed to induce the transient current in the cell which showed the desensitization to quisqualic acid (QA; 10 microM), a non-NMDA receptor agonist. These findings suggest that ATP directly activates small sustained currents, and indirectly induces the transient currents by evoking glutamate release.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed1992

Protein tyrosine kinases belonging to the src family.

There are nine non-receptor-type protein tyrosine kinases that show a high level of similarity in their primary structures and in the structures of their functional domains. Together, they are called the src family. They seem to have common sites specific for oncogenic activation. Recent findings suggest that the kinases are closely associated with cell surface molecules and that they mediate extracellular signals through the activation of their tyrosine kinase activity. They appear to act more on the differentiated phenotype than in haemopoietic cell proliferation. Possible functions of the products of the lck, fyn, lyn and fgr genes in lymphocytes and monocytes are discussed.

Gene Expression Regulation, Neoplastic↗

PubMed1992

Metabolic bone disease following gastrectomy: assessment by dual energy X-ray absorptiometry.

Although disorders in bone metabolism have long been recognized as typical sequelae of gastrectomy, there has until now been no reliable method of providing precise assessment of bone mass, resulting in a variation of reported incidence. In this study, metabolic bone disease was evaluated in a well characterized population: 34 men 2-5 years after gastrectomy; 11 men 6-10 years after gastrectomy; eight men 2-5 years after colonic resection; and 115 healthy men. The age range was 50-69 years. An innovative reliable method of dual energy X-ray absorptiometry was used which allows quantitative assessment of bone mineral content. Measurement of lumbar spine bone mineral density revealed that the mean(s.e.m.) bone mineral density in patients who had had a gastrectomy (2-5 years 0.84(0.03) g/cm2, 6-10 years 0.85(0.05) g/cm2) was significantly lower than that of patients who had undergone colonic resection (0.96(0.04) g/cm2) or healthy men (0.96(0.03) g/cm2). This study demonstrates that a high incidence of bone atrophy is induced at the relatively early period of 2-5 years after gastrectomy.

Absorptiometry, Photon↗

PubMed1992

Bone formation process in porous calcium carbonate and hydroxyapatite.

This study determined the bone formation in porous calcium carbonate (CC) and porous hydroxyapatite (HA) in ectopic sites. The bone formation stimulus was derived from bone marrow cells. CC and HA in the shape of disks were implanted with or without rat marrow cells into subcutaneous sites of syngeneic rats. The CC and HA had identical microstructure: pore size was 190-230 microns, porosity was 50-60% and they were fully interconnected. Bone did not form in any implants without marrow cells (disks themselves), whereas bone consistently formed in the pores of all implants with marrow cells after 4 weeks. The bone formation of both CC and HA occurred initially on surface of the pore regions and progressed toward the center of the pore. Scanning electron microscopy and electron-probe microanalysis revealed a continuum of calcium at the interfaces of both bone/CC and bone/HA implants. These results indicate that the bone formation in calcium carbonate derived from marine corals is comparable to the bioactive hydroxyapatite.

Animals↗