Biomedical subjects

U Ikeda

Publications and source records attributed to U Ikeda.

241 records · Page 14Linked to original sources

PubMed1988

Ouabain inhibits intracellular pH recovery from acidosis in cultured mouse heart cells.

Myocardial ischaemia induces cytosolic acidification, which promotes cardiac damage, dysfunction or arrhythmia. In this study, we investigated the effect of ouabain on the intracellular pH (pHi) in cultured mouse ventricular cells, using 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF). The average resting pHi in myocytes was 7.19. After myocytes were acid-loaded with NH4Cl, the pHi recovered from acidosis to the resting level within a few minutes via amiloride-sensitive Na+/H+ exchange. Ouabain inhibited this pHi recovery dose-dependently with half-maximal inhibition at 3 X 10(-5) M, but did not suppress the ionophore monensin-induced pHi elevation. The inhibition of the pHi recovery from acidosis by ouabain is possibly caused by an inhibition of amiloride-sensitive Na+/H+ exchange, which is secondary to a suppression of Na+ efflux through (Na+, K+) pump. Above results demonstrate the possibility that digitalis promotes intracellular acidosis or inhibits the pHi recovery from acidosis in ischaemic myocardium.

Acidosis↗

PubMed1987

Stimulated synthesis of prostaglandin E2 or leukotrien C4 from myocardial cells is not a cause but a result of their injury under hypoxia.

Cardiac muscle cell injury may be related to metabolic changes associated with a rise in intracellular calcium. The mechanisms by which an elevated Ca2+ can cause injury are uncertain, but injury could occur by activation of any one or several calcium-dependent processes. To examine whether the process is mediated by prostaglandins (PG) or leukotriens (LT), we measured the successive release of creatine kinase (CK), PGE2 and LTC4 that have been reported to induce the cell injury via the arachidonic acid cascade, to the culture medium from myocardial cells under hypoxic or aerobic conditions. CK release, a biochemical marker of muscle cell necrosis, was first detected in the medium of hypoxic cultures at 9 h. Both PGE2 and LTC4 production and release were delayed, being first detected at 12 h after initiating hypoxia treatment. Addition of exogenous PGE2 or LTC4 to the culture medium (1.0 or 10 ng/ml) did not cause any effect on the CK release under aerobic condition. Cyclooxygenase inhibitor, indomethacin (1 X 10(-5) M) or lipoxygenase inhibitor, AA861 (1 X 10(-5) M), reduced the synthesis of PGE2 by 80% or LTC4 by 68% under hypoxia, respectively, but caused no beneficial effect on the CK release. These findings suggest that cardiac muscle cells themselves produce PGE2 and LTC4 after hypoxia and that the production of these compounds merely occurs as a result, but not as a cause of cell injury.

Calcium↗

PubMed1986

Identification of two new calcium dependent hydrolases in the human heart.

We have identified and isolated two new calcium-activated neutral hydrolases from human ventricular muscles. The one is an esterase, of which molecular weight was 300,000, required millimolar concentration of Ca2+, hydrolyzed Ac-Tyr-OEt X H2O, optiaml pH at 7.0. The other is an amidase, of which molecular weight was 70,000, also required millimolar concentration of Ca2+, hydrolyzed a synthetic substrate for chymotrypsin, Suc-Leu-Leu-Val-Tyr-MCA, with optimal pH at 7.2. Both enzymes did not degrade casein or contractile proteins (myosin, actin, troponin and tropomyosin). Their activities were not inhibited by exogenous protease inhibitors, leupeptin, antipain, monoiodoacetic acid and chymostatin, while the amidase activity was blocked by the endogenous inhibitor against calcium-activated neutral protease (CANP). Thus, their characters are different from chymotrypsin or CANP and they seems to be new hydrolases in the human heart.

Amidohydrolases↗

PubMed1979

Chromosome survey of newborn infants in Tokyo: follow-up study for XYY.

In order to ascertain the frequency of chromosome aberrations among newborn infants in Japan, a chromosome survey of a large number of newborn infants is in progress. A series of 10,270 consecutive newborn babies, 5,341 male and 4,929 female, have been screened for clinical manifestations of autosomal aberrations and for sex-chromatin and sex-chromosome aberrations. Chromosome studies were carried out on 185 infants with suspected chromosome aberrations. Of these, 23 had abnormal karyotypes, including 2 males with a 47,XXY complement, 1 female with 45,X complement, 3 males with a 47,XYY complement, 2 with trisomy 13 syndrome, 3 with trisomy 18 (including one mosaicism), 10 with Down syndrome (including 1 mosaicism), 1 with B5p partial trisomy, and 1 with Y-D translocation. Developmental studies of four XYY children and one 45,X girl are in progress.

Chromosome Aberrations↗

PubMedDate not supplied

Gene transfer into rat renal cells using adeno-associated virus vectors.

Adeno-associated virus (AAV) vectors have a number of attractive features, including lack of cytotoxicity, ability to transduce nondividing cells, and long-term transgene expression. We investigated whether rat renal cells could be efficiently transduced with AAV vectors. Rat glomerular mesangial cells were transduced with AAV-lacZ vector containing beta-galactosidase gene in vitro, and the expression of beta-galactosidase was evaluated by X-gal staining and ELISA. For ex vivo experiments, sections of rat kidneys were incubated with AAV-lacZ, and then evaluated by X-gal histochemical staining. The level of beta-galactosidase expression in cultured rat mesangial cells increased in a dose-dependent manner (ranging from 1 x 10(5) to 5 x 10(6) particles/cell). When transduced with 5 x 10(6) vector particles/cell of AAV-lacZ, about 50% of mesangial cells were stained positively with X-gal, and the level of beta-galactosidase expression reached 9.9 +/- 1.5 ng/mg protein. Expression was detectable during the culture period for at least 7 days. X-gal histochemical examination of the ex vivo transduced renal tissue revealed tubular cell and interstitial tissue staining. However, gene transfer was not clearly observed in glomeruli. These findings suggest that AAV vectors have the potential for gene therapy of renal diseases.

Animals↗

PubMedDate not supplied

Plasma endothelin-1 levels in Takayasu's arteritis.

We measured plasma endothelin-1 (ET-1) levels in patients with Takayasu's arteritis to investigate its relationship with the disease activity. We also measured plasma thrombomodulin (TM) levels as a marker of endothelial injury. A significant positive correlation was evident between plasma ET-1 levels and erythrocyte sedimentation rates (ESRs) in patients with Takayasu's arteritis (r = 0.53, p < 0.005). In contrast, plasma levels of TM did not show a significant correlation with ESRs (r = -0.13) ET-1, secreted in this way during the active stages of Takayasu's arteritis, may cause constriction and proliferation of vascular smooth muscle cells and, as a result, progression of luminal narrowing of the affected vessels in this disorder.

Biomarkers↗

PubMedDate not supplied

Plasma cytokine levels in cardiac chambers of patients with mitral stenosis with congestive heart failure.

To ascertain whether elevated levels of circulating proinflammatory cytokines in patients with advanced heart failure are due to congestive heart failure or due to cachexia or infection complicating heart failure, we measured prospectively plasma concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interleukin 2 (IL-2), and interleukin-6 (IL-6) in 12 patients with mitral stenosis with moderate congestive heart failure, but not with cachexia or infection. Blood samples were obtained from the peripheral vein and right and left atria of the patients during percutaneous mitral valvuloplasty. Levels of TNF-alpha, IL-1 beta, IL-2, and IL-6 in the plasma form the peripheral vein and right and left atria of these patients were not elevated compared with those from the peripheral vein of a control group of 10 normal subjects. On the other hand, plasma levels of TNF-alpha but not IL-1 beta, IL-2 or IL-6, were elevated in 4 of 9 patients with congestive heart failure complicated with cachexia and/or infection. Our results suggest that proinflammatory cytokine levels are not elevated in congestive heart failure uncomplicated with cachexia or infection.

Adult↗