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Biomedical subjects

T Iijima

Publications and source records attributed to T Iijima.

At least 325 records · Page 18Linked to original sources
PubMed1989

Mechanisms of beta-adrenoceptor mediated increase in delayed rectifier potassium current.

Experiments were carried out in single ventricular cells of the guinea-pig heart. Isoproterenol, forskolin, intracellularly applied cyclic AMP and 3-isobutyl-1-methylxanthine increased the delayed rectifier potassium current (IK). The effect of isoproterenol was abolished by intracellularly applied guanosine 5'-O-(3-thio-triphosphate). These results indicate that isoproterenol stimulates beta-adrenoceptors to activate adenylate cyclase by mediation through the stimulatory GTP-binding protein, and causes an increase in intracellular cyclic AMP levels. Then IK is probably increased by phosphorylation of the IK-channel protein by cyclic AMP-dependent protein kinase.

Animals↗
PubMed1989

[A cytochemical study of lysosomal system in rat junctional epithelium after intravenous horseradish peroxidase injection].

Lysosome formation was studied in rat junctional epithelium (JE) by detection of acid phosphatase (ACPase) using the cerium reaction method after intravenous injection of horseradish peroxidase (HRP). Intravenously injected HRP was endocytosed by the whole JE, especially at the coronal portion. ACPase activity was also observed in numerous organellae (vacuoles, dense bodies, multivesicular bodies and Golgi cisternae) in the junctional epithelial cells. These ACPase positive organellae often fused with each other, and their contents were mixed in the fused structures. The numbers of the ACPase-positive organellae in the HRP-exposed JE were more numerous than those in the JE without HRP, especially at the coronal portion. Thus, the distribution of the ACPase-positive products in the JE was closely related to that of HRP-positive products. These findings indicated that the whole JE has not only endocytotic ability but also intracellular digestion ability by the lysosomal enzymes.

Acid Phosphatase↗
PubMed1989

Effect of vitamin B12 deficiency on S-adenosylmethionine metabolism in rats.

The effect of vitamin B12 (B12) deficiency on the levels of S-adenosylmethionine (SAM) in tissues and the activities of hepatic methionine synthase, methionine adenosyltransferase and glycine N-methyltransferase were investigated. The striking depression of methionine synthase activity was observed in all rats fed the B12-deficient diets with or without methionine supplementation for 150 days. The SAM level in liver was decreased by B12 deficiency. However, brain SAM level was not affected. The activities of hepatic methionine adenosyltransferase isozymes, alpha-form and beta-form, were decreased by B12 deficiency. Hepatic glycine N-methyltransferase activity in rats fed the low methionine-B12-deficient diet showed a tendency to lower, although the change the activity was not statistically significant, compared with B12-supplemented rats. It is proposed that the fall in the activity of hepatic methionine adenosyltransferase may be one of the causes of the decreased hepatic SAM level in B12-deficient rats.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1989

Effect of vitamin B12-deficiency on the activity of hepatic cystathionine beta-synthase in rats.

The effect of vitamin B12(B12)-deficiency on the activities of hepatic methionine synthase, homocysteine methyltransferase, and cystathionine beta-synthase was investigated in rats. The rats bred from B12-deficient dams were fed the B12-deficient diets for 150 days after weaning. Growth retardation of the B12-deficient rats was already observed on day 30 and continued through 150 days. But dietary supplementation of 0.5% DL-methionine slightly improved the growth retardation. Urinary excretion of methylmalonic acid increased to about 15 mg/mg creatinine and hepatic B12 concentration declined to about 2 ng/g liver after a 150-day feeding of the B12-deficient diets. Hepatic methionine synthase activity in rats fed the B12-deficient diets supplemented with or without methionine decreased to about 5% of B12-supplemented controls. Hepatic betaine-homocysteine methyltransferase activity showed no significant change caused by B12-deficiency. Hepatic cystathionine beta-synthase activity in rats fed the B12-deficient diets supplemented with or without methionine decreased to about 61% and 27% of their B12-supplemented controls, respectively, but the decrease was partially improved by methionine supplementation. In conclusion, the rats bred from B12-deficient dams showed a severe B12-deficiency after a 150-day feeding of the B12-deficient diets. The decrease of hepatic cystathionine beta-synthase activity was supposed to be due to the adaptation by the defect of methionine resynthesis.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1989

Childhood Ki-1 lymphoma. A report of two cases.

Two cases of childhood Ki-1 lymphoma occurred with the expression of Ki-1+/HLA-DR+/IL-2R+/EMA+/Leu-M1-/pan-T antigens-/pan-B antigens- in neoplastic cells. Patient 1 with nodular skin lesions expressed Leu-2a+ in the neoplastic cells and died 14 months later. Patient 2 with lymph node swelling and hepatosplenomegaly exhibited Leu-3a+ in the neoplastic cells and remains free of disease. The Leu-2a+ (case 1) or Leu-3a+ (case 2) findings suggest that the neoplastic cells in both cases were derived from T-lymphocyte lineage. However, Southern's blot analysis did not reveal any clonal rearrangements of T-cell receptor genes in the autopsy material from case 1. The Leu-3a+/Mcs-2+ finding in case 2 may indicate that the neoplastic cells were derived from monocyte/macrophage lineage.

Child, Preschool↗
PubMed1989

Electrophysiological effects of the new antiarrhythmic drug 3-(diisopropylaminoethylamino)-2',6'-dimethylpropionanilide++ + on dog cardiac muscle.

The effects of 3-(diisopropylaminoethylamino)-2',6'-dimethylpropionanilide (AN-132), a new antiarrhythmic drug, on the electrical activities of dog ventricular muscles and Purkinje fibers were studied using standard microelectrode techniques. In ventricular muscles, AN-132 (10(-5)-10(-4) mol/l) decreased the overshoot potential and the maximum rate of rise of the action potential without changing the resting membrane potential, the plateau potential and the action potential duration at a driving rate of 0.5 Hz. These results indicate that AN-132 belongs to class 1 antiarrhythmic drugs. Lidocaine (10(-6)-10(-4) mol/l) failed to affect these parameters under the same conditions. In Purkinje fibers, both drugs decreased the plateau potential and shortened the action potential duration. To subclassify AN-132 among class 1 antiarrhythmic drugs, the kinetics of onset of rate-dependent effect of AN-132 (10(-4) mol/l) was compared with that of lidocaine (10(-4) mol/l), and AN-132 was found to have the slower onset kinetics than lidocaine.

Action Potentials↗
PubMed1989

[Changes of plasma amino acid on the course of septic multiple organ failure].

The changes of plasma amino acid (AA) pattern on the course of septic multiple organ failure (SMOF), and the effect of branched chain amino acid enriched solution (BCAA-S) on the AA pattern were evaluated in thirteen patients who died of SMOF in ICU. The course of ICU was divided into the following three stages. Stage I was a few days after the admission in ICU. Stage II was severe infected state. Stage III was terminal state. Following results were obtained: 1) Total AA value (TAA) of each stage was 2,693 n.mol/ml, 6,666 n.mol/ml and 19,480 n.mol/ml. 2) BCAA/aromatic AA (B/A) of each stage was 1.4, 1.03 and 1.05. Above values were lower than those of normal one (2.44). 3) Most kinds of AA in stage III were exhibited significantly higher than those of stage I as evaluated in absolute value. 4) In the BCAA-S administered group, B/A exhibited higher values than those of control, but, there was no sign of amelioration for SMOF condition in the former group. In severe infected or septic shock state, AA metabolism is deeply deteriorated. So, we can not decide whether BCAA-S given in this condition plays beneficial effect on the course of SMOF or not.

Adult↗
PubMed1988

[Reevaluation of direct radioimmunoassay for plasma cAMP concentration].

In order to evaluate the validity of the direct radioimmunoassay of plasma cAMP level by using Yamasa cyclic AMP assay kit, we determined the cyclic AMP concentration of normal human plasma before and after purification through anion-exchange chromatography. We found that 1) the direct assay before purification gave almost the same values as the indirect assay after purification by anion-exchange chromatography, 2) hemolysis did not affect the results of the direct assay, 3) the plasma cAMP was stable for up to 12 weeks when 5 mM EDTA was added to the blood at the time of sampling and stored below -20 degrees C and 4) the cAMP concentration did not decrease by repeated freeze-thawing of the plasma samples for up to 10 times. These results indicate that the direct radioimmunoassay of plasma cAMP concentration in normal subjects can give the same values as those obtained after purification by anion-exchange chromatography. Although further investigation is needed to clarify whether these results can be equally applied to patient's plasma with various diseases, the direct assay offers a convenient and accurate method to determine plasma cAMP concentration.

Blood Preservation↗
PubMed1988

Stimulation of muscarinic receptor in hippocampal neuron induces characteristic increase in cytosolic free Ca2+ concentration.

Changes in cytosolic free Ca2+ concentration ([Ca2+]i) in response to acetylcholine (ACh) were examined by fura-2 fluorometry in cultured rat hippocampal neurons. ACh (greater than or equal to 10(-5) M) induced an increase in [Ca2+]i composed of fast transient and slow long-lasting phases. Atropine (10(-8) M) abolished the fast component and greatly reduced the slow component. The slow component was selectively blocked by pirenzepine (10(-6) M). The effect of ACh remained partially in a Ca2+-deficient medium where effects of L-glutamate and KCl (50 mM) were abolished. Present results suggest that ACh elevates [Ca2+]i by activation of muscarinic receptor subtypes, one of which is coupled with ion channels and the other of which transduces the ACh binding to mobilization of intracellularly stored Ca2+.

Acetylcholine↗
PubMed1988

Wall structure of arteriovenous anastomoses in the rabbit ear. Combined light-, scanning- and transmission electron-microscopic studies.

The wall structure of arteriovenous anastomoses in the rabbit ear was investigated. (1) Clusters of epithelioid smooth muscle cells form 3-4 longitudinally oriented plicae. The channel shows a single, irregularly outlined lumen, and its wall is very thin between adjacent plicae. (2) Endothelial cells covering the plicae protrude into the lumen, thus suggesting active contraction or shortening of the plicae. (3) The tunica adventitia is composed of 4-6 sheaths of flat fibroblasts, which may serve as a barrier to prevent loss of neurotransmitters. Processes of some of the fibroblasts also extend into the tunica media. (4) The tunica media is composed of an outer circular layer of typical smooth muscle cells, and an inner longitudinally running plica of ramified smooth muscle cells. Wide intercellular spaces between these ramified cells are filled with collagen fibrils, microfibrils, amorphous intercellular substances, and fibroblasts. Fibroblasts form close membrane contacts with each other, and with the smooth muscle cells. (5) Fibroblasts and other connective tissue components may function as an elastic support during active motility of the anastomotic channel.

Animals↗
PubMed1988

Angiographic diagnosis of the degree of serosal invasion of carcinoma of the colon.

Angiography using Prostaglandin E1 was performed on 38 patients with carcinoma of the colon in order to diagnose the degree of serosal cancer invasion. The findings at angiography were classified into four groups: 1) AG-S3, abnormal change (irregularity and/or encasement) up to marginal vessels; 2) AG-S2, abnormality up to vasa recta; 3) AG-S1, abnormality of penetrating branches of vasa recta within the wall of the colon; and 4) AG-S0, no distinct findings of above-mentioned vessels. These angiographic findings were compared with both macroscopic and microscopic serosal cancer invasion. Angiographic diagnosis is in accord with the macroscopic findings in 84.2 percent of cases. Angiographic diagnosis is in accord with the microscopic findings in 32.4 percent of cases. Macroscopic findings confirm the angiographic diagnosis precisely but the conflict with microscopic findings should not be overlooked. This may be the result of inflammatory change, adhesion, and fibrosis around carcinoma of the colon.

Adult↗
PubMed1988

Pharmacoangiographic diagnosis of venous invasion of carcinoma of the colon with reference to liver metastases.

Angiography using prostaglandin E1 was performed on 34 patients with carcinoma of the colon in order to define the degree of venous invasion. Venous findings on angiogram (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 vasa recta; AG-V0, no distinct findings on the vein. These venous findings were compared with histologic subserosal venous invasion that was diagnosed with both hematoxylin and eosin and elastica van Gieson's staining. When angiographic findings were compared with histologic subserosal venous invasion, the results of AG-V2, AG-V1, and AG-V0 showed a positive correlation of 92.3 percent, 46.7 percent, and 16.7 percent, respectively. The angiographic findings were also correlated with the degree of fibrosis around the carcinoma of the colon. The incidence rate of liver metastasis in a group of AG-V2 was 46.2 percent. In AG-V1 it was 26.7 percent and in AG-V0 0 percent. In the course of the postoperative follow-up, liver metastases appeared in two cases of AG-V2 and AG-V1, respectively. This finding may suggest the presence of liver micrometastases at the time of surgery.

Alprostadil↗
PubMed1988

A combination therapy of vitamin K1 and bile acid on hemorrhagic diathesis in patients with decompensated liver cirrhosis.

This paper presents a study of treatment involving vitamin K1 (VK1) accompanied by bile acids for hemorrhagic diathesis that was applied 42 times in 35 patients with decompensated liver cirrhosis. The hepaplastin test (HPT) value showed no change during the administration of VK1 alone. The HPT value elevated significantly, however, after the administration of VK1 with bile acid, especially when using ursodeoxycholic acid (UDCA). The HPT value in patients treated with VK1 in addition to UDCA before treatment with 53.2% +/- 10.2% (mean +/- SD) and after that for 2.1 +/- 1.1 months (mean +/- SD) with 74.7 +/- 16.8% showed a significant difference (p less than 0.001). On the other hand, no significant difference was noted between the HPT value of 57.2 +/- 13.6% before and that of 62.9 +/- 13.9% after the treatment in patients treated using VK1 in conjunction with chenodeoxycholic acid (CDCA). These results indicate that the therapy incorporating VK1 and bile acid, especially UDCA, is useful for reducing the hemorrhagic tendency in patients with decompensated liver cirrhosis who show no improvement using VK1 alone.

Chenodeoxycholic Acid↗
PubMed1988

Transient increase of the intracellular Ca2+ concentration during chemotactic signal transduction in Dictyostelium discoideum cells.

In general, calcium has been believed to control a variety of cellular processes as a signal transducer, with a high degree of spatial and temporal precision. For the determination of intracellular free-calcium concentrations [( Ca2+]i), the highly selective Ca2+ indicators, quin2/AM and fura2/AM, have been widely used in many mammalian and plant cells. However, intact cells of the cellular slime mold Dictyostelium discoideum Ax-2 are generally impermeable to externally added drugs, thus resulting in a failure to determine [Ca2+]i. Introduction of quin2/AM and fura2/AM by electroporation allowed us to measure [Ca2+]i in D. discoideum cells. The fluorescence images of fura2-loaded single cells showed that resting [Ca2+]i in vegetative and aggregation-competent cells is around 50 nM. Caffeine (10 mM) gave a transient increase in [Ca2+]i, which illustrated a normal responsive ability of electroporated cells to the externally added stimulus. Application of the chemoattractant, cAMP (20 nM), to aggregation-competent cells induced a rapid increase in [Ca2+]i within 1-2 s, and the [Ca2+]i level increased to about four-fold higher than the resting [Ca2+]i within 30 s of chemotactic stimulation. This was followed by a gradual decrease of [Ca2+]i to the basal level. These results strongly suggest that [Ca2+]i is a primary messenger in signal transduction, particularly during the chemotactic response of Dictyostelium cells.

Caffeine↗