Showing papers by "Kyushu University published in 1987"

Ohmic conductance through the inwardly rectifying K channel and blocking by internal Mg2

Abstract: The inwardly rectifying K channel provides the resting K conductance in a variety of cells1–4. This channel acts as a valve or diode, permitting entry of K+ under hyperpolarization, but not its exit under depolarization. This behaviour, termed inward rectification, permits long depolarizing responses which are of physiological significance for the pumping function of the heart and for fertilization of egg cells5. Little is known about the outward currents through the inwardly rectifying K channel, despite their great physiological importance, and the mechanism of inward rectification itself is unknown. We have used improved patch clamp techniques to control the intracellular media, and have recorded the outward whole-cell and single-channel currents. We report here that the channel conductance is ohmic and that the well-known inward rectification of the resting K conductance is caused by rapid closure of the channel accompanied by a voltage-dependent block by intracellular Mg2+ ions at physiological concentrations.

A novel class (H3) of histamine receptors on perivascular nerve terminals.

Abstract: Two types of histamine receptor, the H1- and H2-receptors, are found not only on vascular smooth muscle cells but on the perivascular autonomic nerve terminals. Activation of the prejunctional histamine receptors modifies transmitter release from the nerve terminals. Recently, histamine was shown to inhibit its own release from depolarized slices of rat cerebral cortex. This phenomenon was found to be mediated by a novel class of histamine receptor, the H3-receptor, that was pharmacologically distinct from the H1- and H2-receptors. Up to now, there has been no indication whether this third class of histamine receptor is present in any tissue other than the brain. We report here that histamine depresses sympathetic neurotransmission in the guinea-pig mesenteric artery by interacting with histamine H3-receptors on the perivascular nerve terminals. The pharmacological properties of these receptors are similar to those reported for the H3-receptors in the brain. Our data provide evidence for the existence of H3-receptors in the autonomic nervous system.

Carcinoma of the ampulla of Vater : a clinicopathologic study and pathologic staging of 109 cases of carcinoma and 5 cases of adenoma

Abstract: A total of 109 cases of carcinoma and 5 cases of adenoma of the ampulla of Vater were studied by preparing 5-mm step-wise whole tissue sections in each case. Carcinoma of the ampulla of Vater could be divided into four stages (I, II, III and IV), according to the microscopically verified extent of involvement by the tumor. All 12 patients with a Stage I tumor, defined as one restricted to within the muscle of Oddi as a boundary, showed no lymph node involvement and carried an excellent life expectancy with a relative 5-year survival rate of 85%. Thus, categorization of such a tumor as early carcinoma of the ampulla of Vater is valid. Excluding two unclassifiable cases, the remaining 95 patients with Stage II, III, or IV tumors extending beyond the boundary of Oddi carried relative 5-year survival rates of 11%, 25%, or 24%, respectively. Of the 109 carcinomas, 20 had areas of unequivocal adenoma at the margins, and of the five adenomas, two larger ones had foci of atypical epithelium suggestive of carcinoma in situ. These findings show the close relationship between adenoma and adenocarcinoma of the ampulla of Vater.

HLA-DQ is epistatic to HLA-DR in controlling the immune response to schistosomal antigen in humans.

Abstract: Antigens that produce an antibody response in some members of a species may fail to do so in others. The response to an antigen is controlled by a gene termed the immune response (Ir) gene, which is transmitted as a single dominant trait. We have provided evidence for similar immune suppression (Is) genes which control non-responsiveness through the antigen specific suppressor T cell1–6. The non-responsiveness is also dominantly inherited and the Is genes are linked to the histocompatibility (HLA) antigen system. Here we report that the HLA-DR2 molecule from a non-responder haplotype (HLA-Dw12-DR2-DQwl) is required for the proliferative T cell response to schistosoma japonicum (Sj) antigen, as a restriction element, indicating that the HLA-DR2 is the product of the Ir gene, and that the HLA-DQwl molecule of the non-responder haplotype is important in the antigen-specific suppression of the response to this antigen, suggesting that it is the product of the Is gene. We therefore conclude that the HLA-DR and DQ molecules, which are controlled by the distinct genes in the MHC multigene family, regulate immune response and immune suppression and that the gene for HLA-DQ is epistatic to that for HLA-DR in controlling the immune response to schistosomal antigen in humans.

Isolation and characterization of the active cDNA of the human cell cycle gene (RCC1) involved in the regulation of onset of chromosome condensation.

Abstract: The human RCCI gene was cloned after DNA-mediated gene transfer into the tsBN2 cell line, which shows premature chromosome condensation at nonpermissive temperatures (39.5-40°C). This gene codes for a 2.5-kb poly(A) + RNA that is well conserved in hamsters and humans. We isolated 15 cDNA clones from the Okayama-Berg human cDNA library, and found two that can complement the tsBN2 mutation with an efficiency comparable to that of the genomic DNA clone. The base sequences of these two active cDNA clones differ at the 5' proximal end, yet both have a common open reading frame, encoding a protein of 421 amino acids with a calculated molecular weight of 44,847 and with seven homologous repeated domains of about 60 amino acids. This human RCC1 gene was located to human chromosome 1 using sorted chromosomal fractions.

New application of complex magnetic materials to the magnetic refrigerant in an Ericsson magnetic refrigerator

Abstract: A complex new magnetic refrigerant, suitable for the ideal Ericsson cycle, has been investigated. Above ∼15 K it is necessary to use ferromagnets as a magnetic refrigerant. However, temperature variation for the magnetic entropy change in a homogeneous ferromagnet is not suitable for the Ericsson cycle. The present paper verifies, from theoretical analysis, that a complex ferromagnetic material, for instance, (ErAl2)0.312(HoAl2)0.198 (Ho0.5Dy0.5Al2)0.490, has the most suitable characteristics for the ideal Ericsson cycle, including two kinds of isomagnetic field processes. On the basis of the above consideration, a sintered layer structural complex has been prepared, composed of three kinds of RAl2.15 layers, where R’s are rare‐earth atoms. From specific heat measurements made on this complex, its entropy and entropy change have been determined. It has been concluded that the complex magnetic material is the most hopeful refrigerant for the Ericsson cycle.

Gene Structure of Human Cytochrome P-450(SCC), Cholesterol Desmolase

Abstract: Four independent clones containing a part of the P-450(SCC), cholesterol desmolase, gene were isolated from human genomic libraries using bovine P-450(SCC) cDNA as a probe. These clones covered the entire P-450(SCC) gene except for a part of the 1st intron. The gene is at least 20 kb long and is split into 9 exons by 8 introns. The sequence analysis revealed that the nine separated exons code for a primary structure consisting of 521 amino acids which shows 72% homology with that of bovine P-450(SCC). A CATT sequence and a TATAAT sequence, which are possibly a "CAT" box, and a "TATA" box, respectively, are present 129 and 91 bp upstream from the initiation codon. An unusual exon/intron junctional sequence that begins with GC was found in the 6th intron of the gene. A putative extension peptide consisting of 39 amino acids was found in the sequence of human P-450(SCC) by comparison with that of the bovine counterpart. Two conserved regions were found in the extension peptide of these two forms of P-450(SCC), suggesting a functional role of the portions in the mitochondrial localization and processing of P-450(SCC) precursor. The mature form of human P-450(SCC) has only one cysteine residue, which was located in the center of the HR2 region (Gotoh et al. (1983) J. Biochem. 97, 807-817). This observation established beyond doubt that the sole cysteine residue in the HR2 region is the 5th ligand to the heme.

Fluorescence and photoisomerization of azobenzene-containing bilayer membranes

Abstract: Spectroscopic and photoisomerization behavior of aqueous bilayer aggregates of azobenzene-containing amphiphiles was examined. The azobenzene bilayers assume different chromophore orientations, depending on the component structure. Some of the azobenzene bilayers were found to be fluorescent, and the fluorescence intensity decreased as the chromophore orientation changed from the tilted head-to-tail type to the parallel type. Emission quenching was observed in the presence of extremely small amounts of a bound cyanine dye. In the trans-to-cis photoisomerization of the bilayers, the rate in the gel state decreased with changing chromophore orientations from the head-to-tail type to the parallel type. The rate was much larger and unaffected by the molecular structure, in the case of the liquid-crystalline bilayers and of the azobenzene amphiphiles isolated in inert bilayer matrices. In the phase-separated system, photoisomerization occurred between the unclustered isomers. The emission was quickly lost by the formation of the cis isomer. The photoisomerization was suppressed in the presence of the cyanine, probably due to energy transfer to the cyanine and sensitization of the reverse photoisomerization by the cyanine. An energy level diagram was constructucted which includes excited states characteristic of the bilayer and explains the photophysical and photochemical processes. Finally, implications of the present findingmore » in relation to light energy harvesting systems were discussed.« less

Features of 4-aminopyridine sensitive outward current observed in single smooth muscle cells from the rabbit pulmonary artery.

Abstract: The 4-aminopyridine (4AP) sensitive outward current of enzymatically dispersed single smooth muscle cells of the rabbit main pulmonary artery were investigated using the voltage clamp method. When the cell was exposed to physiological salt solution (PSS) in the bath and high K+ in the pipette no inward current was generated by depolarization of the membrane, but when 4AP was present in the bath or when Cs+ with tetraethylammonium+ (Cs+-TEA+) in the pipette, an inward current was generated. This current was enhanced by Ba2+ or high Ca2+ and was blocked by inorganic or organic Ca2+ channel blockers.

Epithelioid hemangioma versus Kimura's disease. A comparative clinicopathologic study.

Abstract: A clinicopathologic and immunohistochemical study of eight cases of epithelioid hemangioma and 11 cases of Kimura's disease was performed. Patients with epithelioid hemangioma (EH) ranged in age from 15 to 56 years (mean, 37 years) and had small papular or nodular lesions occurring most often on the face and scalp. The lesions were less than 2.0 cm in diameter. There were irregularly hypertrophic vascular structures with swollen endothelial cells and of a variable lymphoid infiltrate with eosinophils. The clustering of small vessels around the arteries or veins was another distinctive feature. Arteriovenous shunts were evident in three lesions. Patients with Kimura's disease, however, presented large solitary or multiple nodules occurring most commonly in the periauricular region. Six patients had a history of regional lymphadenopathy; three patients had eosinophilia of the peripheral blood. Microscopically, the distinctive features were of numerous lymphoid follicles and a salient eosinophilic infiltrate. These lymphoid follicles possessed distinct germinal centers and contained an increased number of dendritic cells. Although some small-vessel proliferation was noted, it was not as distinctive as for patients with epithelioid hemangioma. We conclude from this study that the two conditions should be considered different entities.

Structure and expression of cDNA for an inhibitor of blood coagulation isolated from human placenta: a new lipocortin-like protein.

Abstract: An inhibitor of blood coagulation, a new protein with an apparent molecular weight of 34,000 and an isoelectric point of 4.9, was purified from human placental tissue by EDTA extraction. Five cDNA clones were isolated from the human placental lambda gt11 cDNA library using the mouse monoclonal antibody raised against the coagulation inhibitor as the probe. The longest insert consists of 1,566 nucleotides, and contains 960 nucleotides entirely encoding the 320 amino acids of the inhibitor, and a poly A tail. The deduced amino acid sequence was corroborated by chemical analyses of the protein. The entire amino acid sequence shows homology to those of lipocortin I, lipocortin II, and endonexin-related proteins. The cDNA for the inhibitor was expressed in Escherichia coli under the regulation of the trc promotor of the plasmid pKK233-2. The resulting recombinant protein manifested inhibitory activities against both blood coagulation and phospholipase A2 activity, as did the coagulation inhibitor isolated from human placenta.

Electrical responses of smooth muscle cells during cholinergic vasodilation in the rabbit saphenous artery.

Abstract: Isolated smooth muscle tissues of the rabbit saphenous artery precontracted with norepinephrine (NE) were relaxed by acetylcholine (ACh, greater than 10(-7) M) or oxotremorine (greater than 10(-7) M), through the activation of muscarinic receptors, only when the endothelial cells were intact. ACh (greater than 10(-7) M) transiently hyperpolarized the membrane (1-4 minutes) with an associated decrease in the membrane resistance, either in the presence or absence of NE, and these changes ceased during the continuous application of ACh. The ACh-induced transient hyperpolarization was not generated after mechanically removing the endothelium or by treatment with atropine. Oxotremorine (up to 10(-5) M) did not alter the membrane potential in the presence or absence of the endothelium. NE (10(-6) M) depolarized the smooth muscle membrane, which remained unchanged by additional application of ACh or oxotremorine for more than 5 minutes, or after removal of the endothelium. The excitatory junction potential generated by perivascular nerve stimulation was inhibited by ACh (greater than 10(-9) M) or oxotremorine (greater than 10(-9) M) in a concentration-dependent manner. These inhibitory actions of ACh or oxotremorine were blocked by atropine but were not affected by removal of the endothelial cells. These results suggest that the inhibitory actions of muscarinic agonists on electrical responses of smooth muscle cells of the rabbit saphenous artery were mainly indirect, i.e., a release of inhibitory substances from the endothelial cells and the inhibition of adrenergic transmission. The former required higher concentrations of ACh or oxotremorine, thereby suggesting that the latter may be more important for vasodilation related to cholinergic mechanisms.

Langerhans cells and prognosis in patients with gastric carcinoma.

Abstract: Infiltration of Langerhans cells (LC) and macrophages into tumor tissues was investigated using immunohistochemical methods, anti-S-100 protein and anti-lysozyme antibodies in 174 cases of gastric carcinoma. Varying population densities of S-100-positive LC were noted in tumor tissues; lysozyme-positive macrophages, however, were found in almost equal quantities. LC were mainly interspersed among the tumor cells, whereas macrophages were present in the stroma and around the necrotic foci. Although the survival time of patients with Stage I, II or IV gastric carcinoma did not relate to the density of LC, survival time in Stage III patients correlated well with the density of LC. In patients with a marked infiltration of LC, survival time was longer than in cases of only a slight infiltration (P less than 0.001). Therefore, LC in immunological defense mechanisms of the host against the tumor may be clinically effective in a certain phase of tumor development.

An analysis of the delayed outward current in single ventricular cells of the guinea-pig.

Abstract: Properties of the delayed outward current (IK) in ventricular myocytes of the guinea-pig were studied using the whole cell clamp method. The experiments were performed under conditions in which IK was enhanced by application of isoproterenol while the Ca2+ current was eliminated by Ca2+-removal and by the addition of Cd2+. The reversal potential (Erev) of IK, determined from the current tails, was about 10 mV less negative than the K+ equilibrium potential. This was estimated by examining the reversal potential of the inward rectifier K+ current in Ba2+-containing solution, or from the Nernst equation. The Erev--log[K+]o relationship had a slope of 49 mV per tenfold change in [K+]o. In Na+-free solution, Erev became more negative. Thus, although the major charge carriers in IK are K+ ions, Na+ ions may also contribute in part to this current. The PNa/PK ratio in IK, calculated by applying a Goldman-Hodgkin-Katz relation to the reversal potential, was 0.016. The activation of IK during depolarization showed a sigmoidal time course at the onset, while the time course of the current tails was monoexponential at voltages more negative than-50 mV, but biexponential at more positive voltages. These observations can be explained by the conductance equation of the Hodgkin-Huxley type in which the kinetic variable is raised to the second power. These and other features of IK observed in the ventricular cells are discussed in comparison to the properties of similar current systems reported in other cardiac preparations.

Development of new surfactant for liquid surfactant membrane process

Abstract: To obtain more stable W/O emulsion for liquid surfactant membrane technique, a series of glutamic acid dialkyl esters and dialkyl type quaternary ammonium salts as new surfactants in place of Span 80 and polyamine were synthesized. The adsorption equilibria between aqueous solution and organic solution containing the synthesized surfactants were elucidated and the stability of liquid surfactant membrane made of these surfactants was examined in a stirred tank. A series of synthesized surfactants having two long alkyl chains in hydrophobic site gave more stable emulsion at a lower concentration compared with Span 80 and polyamine. Among them, glutamic acid dioleyl ester formed the most stable emulsion.