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Biomedical subjects

T Iijima

Publications and source records attributed to T Iijima.

At least 361 records · Page 20Linked to original sources
PubMed1987

Determination of binding constants for N-acetyl-D-glucosamine oligomers with lysozyme.

A method to determine intrinsic binding constants of lysozyme with substrate analogues such as N-acetyl-D-glucosamine dimer and trimer is proposed. The method is based on the competitive interaction of an anionic azo dye with substrate analogues for lysozyme. There are two binding sites for substrate analogues and dyes, respectively, on lysozyme. One binding mode of the substrate analogues to subsites D-F on lysozyme was non-competitive, and another binding mode to subsites A-C was competitive with the dye. From the binding constants obtained it is suggested that the binding of the substrate analogues to subsite D on lysozyme is weaker than the binding to the other subsites.

Acetylglucosamine↗
PubMed1987

[Diagnosis of degree of serosal invasion of carcinoma of the colon by angiography].

Angiography (AG) using Prostaglandin E1 was performed on 35 cases of carcinoma of the colon in order to diagnose the degree of serosal invasion. The findings of AG were classified into 4 groups: AG-S3, abnormal change (like irregularity and/or encasement) up to marginal vessels; AG-S2, abnormality up to vasa recta; AG-S1, abnormality of penetrating branches of vasa recta; AG-S0, no distinct findings of above mentioned vessels. 1) Diagnosis of AG is in accord with the visible postoperative findings in 82.9%. 2) Diagnosis of AG is in accord with the histopathological findings in 32.4%. 3) Postoperative examinations confirmed the AG diagnosis precisely but the conflict with histopathological findings should not be overlooked. This may be the results of inflammatory change, adhesion and fibrosis around the carcinoma of the colon.

Adenocarcinoma↗
PubMed1987

[Angiographic diagnosis of venous invasion with reference to liver metastasis of carcinoma of the colon].

Angiography using Prostaglandin E1 was performed on thirty one cases with carcinoma of the colon in order to define the degree of venous invasion. Venous findings (occlusion and/or encasement) were classified into three groups: AG-V2, above mentioned venous findings up to marginal vein; AG-V1, these findings up to the vein of vasa recta; AG-V0, no distinct findings on the vein. 1) When angiographic findings were compared to histological findings of subserosal venous invasion, the results of AG-V2, AG-V1 and AG-V0 showed a positive correlation of 91.7%, 46.2% and 16.7%, respectively. 2) The angiographic findings were also correlated with the degree of fibrosis around carcinoma of the colon. 3) The incidence rate of liver metastasis in a group of AG-V2 was 50%. In AG-V1 it was 30.8% and in AG-V0 0%. 4) In the course of the postoperative follow-up, liver metastasis appeared in 2 cases of AG-V2 and AG-V1, respectively. The finding may suggest the existence of the liver metastases at the time of operation.

Alprostadil↗
PubMed1986

Effects of the external pH on Ca channels: experimental studies and theoretical considerations using a two-site, two-ion model.

Some effects of the external pH on Ca channels were studied in a hybridoma cell line (mAb-7B), by using the whole-cell configuration of the patch-clamp technique. As the pH was lowered, both the activation and the inactivation curves shifted toward less negative membrane potentials, suggesting a pH-induced decrease of an external negative surface potential, sensed by the mechanism of gating. The potential for half-activation, V1/2, and that for half-inactivation, Vh, were related by a straight line with a slope of one. The inward current varied exponentially with V1/2, as would be expected if the field inside the channel and the Ca2+ concentration at the entrance were sensitive to the surface potential. However, the reversal potential and the outward current were unaltered by changes in the pH. Under the hypothesis that the channel senses the surface potential, all these results, as well as the nernstian behavior of the reversal potential with respect to Ca2+, observed in previous studies, are accounted for by a three-barrier, two-ion model for a channel, provided it is assumed that the potential in the channel drops almost entirely across the barrier adjacent to the external solution.

Animals↗
PubMed1986

Observations on the Taiwanese strain of Leucocytozoon caulleryi (Haemosporina) in chickens.

The Taiwanese strain of Leucocytozoon caulleryi was isolated from an infected chicken in Taipei, Taiwan, and established in chickens and biting midges Culicoides arakawae from Japan. Sporogony of the strain in C. arakawae was completed on day 3 after the infective blood meals at 25 degrees C. Sporozoites isolated from the salivary glands of C. arakawae on days 3 or 4 after feeding caused infection in all the chickens inoculated. The strain showed high pathogenicity for chickens. Mortality of chickens rose with an increase in the number of sporozoites inoculated. The prepatent period for chickens inoculated with sporozoites was 14 days. Parasites appeared in the peripheral blood of chickens on day 15 and disappeared on day 26 after sporozoite inoculation. Soluble antigens were found in the sera of chickens infected with the strain between 10 and 17 days after inoculation, and homologous antibodies appeared after 17 days. Antigens prepared from sera, schizonts, merozoites, and gametocytes of the Taiwanese strain reacted with the sera of chickens infected with the same strain or the strain isolated in Japan. The chickens that recovered from a primary infection with the Taiwanese strain demonstrated complete resistance to reinfection with the same strain or the the strain isolated in Japan.

Animals↗
PubMed1986

Modification by nicorandil and carbachol of the inward calcium current in single cells of the guinea-pig heart.

Effects of nicorandil and carbachol on the inward calcium current were studied in single heart cells isolated from the guinea-pig using a collagenase dispersion method. The inward calcium current was obtained in the absence of outward potassium currents by intra- and extra-cellular perfusion of the cell with Cs+-solutions. Nicorandil (0.3 mM) failed to modify the inward calcium current in the atrial cell. In the ventricular cell the inward calcium current was increased by isoproterenol (1 micron). The augmentation of the inward calcium current was abolished by carbachol (1 micron) but was not changed by nicorandil (0.3 mM). From these results it can be concluded that nicorandil has no direct effect on the inward calcium current even when the inward calcium current is previously augmented by isoproterenol.

Animals↗
PubMed1985

Quinacrine-induced dilation of the rat cecum and degeneration of large granular vesicle-containing neurons in the myenteric plexus.

Intraperitoneal injection of quinacrine (100 mg/kg) into rats causes marked dilation of the cecum about one week after the injection, but the jejunum remains its normal size. The morphological changes induced in the myenteric plexus and the longitudinal and circular muscle layers of both the cecum and the jejunum have been examined by fluorescence and electron microscopy 1.5 h to 2 weeks after the injection. In the cecum, 1.5 h after the injection, the granular fluorescence of quinacrine was apparent in many ganglion cells of the myenteric plexus and in the nerve fibers in the muscle layers. In connection with the granular fluorescence, numerous lysosomal dense bodies appeared in ganglion cells and axons, and subsequently the degeneration of the neurons was observed at ultrastructural level. The lysosomal dense bodies often contained many large granular vesicles of 95-140 nm in diameter. The number of lysosomal dense bodies in the axons was greatest 3-7 days after the injection. Although the axon type sensitive to quinacrine could not be specified, axons containing many large granular vesicles were the predominate type. Fibrosis in the outer longitudinal muscle layer was another characteristic resulting from quinacrine administration. Proliferation of the rough-surfaced endoplasmic reticulum and of the Golgi complex and a concomitant decrease in the number of myofilaments became evident in many smooth muscle cells 3-7 days after the injection; the intercellular spaces became enlarged 7 days after quinacrine administration. These changes and the dilation of the cecum showed considerable recovery 2 weeks after the injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Membrane currents and their modification by acetylcholine in isolated single atrial cells of the guinea-pig.

The ionic currents in isolated single atrial cells of the guinea-pig heart were analysed by the patch-clamp technique applied to whole-cell recordings and the effects of acetylcholine (ACh) on the membrane potential and currents were studied. Resting and action potentials of single isolated cells were normal. Upstroke velocity was sensitive to tetrodotoxin. Action potential duration was slightly shorter than in multicellular preparations. Voltage-clamp experiments demonstrated the presence of a Ca2+ current (iCa), and inward rectifying and outward rectifying K+ currents. The Ca2+ current was abolished by 2 mM-Co2+ or 10(-6) M-D600, and the K+ currents were greatly reduced by intracellular application of Cs+ using the patch electrode and simultaneously superfusing the cell with 5 mM-Cs+ Tyrode solution. Acetylcholine shortened the action potential duration in a dose-dependent manner. The threshold dose of ACh was about 10(-9) M and the maximal effect was obtained with 10(-6) M. The resting membrane potential was hyperpolarized by 1-3 mV. ACh (10(-8)-10(-6) M) increased the K+ currents both on depolarization and on hyperpolarization in a dose-dependent manner in the presence of 10(-6) M-D600. The ACh-induced K+ outward current revealed a progressive deactivation ('relaxation'), with a time constant of 111 +/- 16 ms at around 0 mV. When the K+ outward currents were minimized with Cs+, the reduction of iCa by 10(-8) M-ACh was insignificant, and became 17 +/- 2.5, 26 +/- 3.5 and 26 +/- 5% of the control value in 10(-7), 10(-6) and 10(-5) M-ACh, respectively. The inactivation time course of iCa recorded from the Cs+-loaded cells was not affected by 10(-7) M-ACh. These results suggest that ACh activates predominantly a K+ conductance in the guinea-pig atrium. The superimposition of a relaxing K+ outward current on iCa may lead to over-estimation of the decrease in iCa.

Acetylcholine↗
PubMed1985

Attenuation of muscarinic cholinergic inhibition by islet-activating protein in the heart.

Experiments were carried out to investigate the influence of islet-activating protein (IAP), a pertussis toxin, on the autonomic regulation of cardiac function. In atria isolated from rats given intravenous IAP (0.125-1.0 micrograms/100 g body wt) 12-72 h prior to experiments, the negative chronotropic and inotropic actions of carbachol were attenuated in a dose- and time-dependent manner. The inhibitory action of carbachol in the absence of isoproterenol and its attenuation by IAP were not associated with any changes in tissue adenosine 3',5'-cyclic monophosphate (cAMP) levels. In addition, carbachol decreased the isoproterenol-induced elevation of cAMP levels and inhibited the positive chronotropic and inotropic responses to isoproterenol. The inhibitory action of carbachol on the isoproterenol-induced functional and cAMP responses was also reduced by the IAP treatment. The increase in tissue guanosine 3',5'-cyclic monophosphate (cGMP) levels produced by carbachol was likewise abolished by the IAP treatment. These results indicate that IAP treatment attenuates the inhibitory actions of carbachol elicited via muscarinic receptors through both cAMP-dependent and cAMP-independent subcellular processes.

Animals↗
PubMed1985

[Calcium ion channels in cardiac cell membranes].

Understanding of the electrophysiological properties of the calcium channel in cardiac cell membranes has been hampered because of the difficulties in interpreting voltage-clamp data. Recently, new techniques for isolation of adult heart cells, internal dialyzation of the cell and analysis of the single ion channel current have been established. Some of the previous results and concepts obtained in intact cardiac tissues have been confirmed and new understanding of the nature of the calcium channels has been gained by the techniques. In this article, the author reviews the electrophysiological and electropharmacological properties of the calcium ion channels in cardiac cell membranes. Especially, emphasis is placed on new information gleaned from the new techniques.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1985

Abolition by nicorandil of spontaneous action potentials of the small atrio-ventricular node preparation of the dog.

Effects of carbachol and nicorandil on spontaneous action potentials were examined in the small atrio-ventricular (A-V) node preparation of the dog. Carbachol (3 X 10(-6) M) definitely hyperpolarized the membrane potential and abolished the spontaneous activity. Nicorandil (3 X 10(-4) M) also abolished the spontaneous activity but the membrane potential became quiescent at -65 mV, which was less negative than the maximum diastolic potential. From these results it appears that nicorandil may increase the potassium conductances but not hyperpolarize the membrane potential because the background potassium conductance is little developed in the nodal cells.

Action Potentials↗
PubMed1985

Effects of a new calcium entry blocking agent, KB-944, on the membrane potential and currents of mammalian ventricular muscle cells.

KB-944 (10(-5)-10(-4) M) decreased the action potential duration measured at 30% repolarization and hyperpolarized the resting membrane potential in ventricular trabeculae of the dog heart. In single ventricular cells of the guinea-pig heart, KB-944 (10(-4) M) abolished the slow inward current and produced an outward shift of the late current measured at the end of 200 msec clamp pulse. From these results it appears that KB-944 selectively blocks the slow inward current and may increase the background potassium conductance.

Action Potentials↗