To determine the mechanism of the antiatherosclerotic effect of estrogen, we investigated the effect of estrogen on endothelial nitric oxide synthase (NOS-3). Preincubation with a physiologic ...concentration of 17 β-estradiol (10
−12-10
−8 M) over 8 hours significantly enhanced the activity of NOS-3 in endothelial cells of cultured human umblical vein (HUVEC) and of bovine aortas (BAEC). 17 β-estradiol also enhanced the release of nitric oxide (NO) as measured by an NO selective meter and NO
−
2/NO
−
3 metabolites of NO, from endothelial cells. Western blot showed a similar effect of 17 β-estradiol on NOS-3. The estrogen receptor antagonists, tamoxifen and ICI182780, each inhibited the effect of 17 β-estradiol by 80%. The effect of 17 β-estradiol gradually decreased in cells beyond the 10th passage and was not significant in cells beyond the 16th passage. Immunocytochemistry showed the existence of estrogen receptor in HUVEC and BAEC (less than 5 passages) and the sparseness of the existence in BAEC beyond the 16th passage. Estrogen increases NOS-3 via a receptor-mediated system, and estrogen receptor, which appeared to be altered by cell senescence, could be important in the release of NO from endothelium.
The grounding resistance of surge arresters (Arrs) for the lightning protection of power distribution lines is generally maintained below 30Ω in Japan. Therefore, electric power companies have been ...spending a large amount of money on the construction and maintenance of low grounding resistances. In this paper, the influence of grounding resistance on lightning protection measures is clarified for power distribution lines with both a ground wire (GW) and Arrs by EMTP analysis and experiments. These results showed that even if the grounding resistance of Arrs becomes high, effectiveness of lightning protection is hardly decreased. Moreover, the results indicated that it is more important for constructing a rational lightning protection system to install a lot of lightning devices on power distribution lines than to lower the grounding resistance of Arrs.
Summary
Severe and life‐threatening donor‐transmitted human T‐cell leukemia virus type 1 (HTLV‐1) infections after solid organ transplantation have been reported. However, in HTLV‐1‐infected ...recipients, graft and patient survival were not fully evaluated. A total of 140 patients underwent living donor liver transplantation (LDLT). Of these, 47 of 126 adult recipients showed indications of hepatitis C virus (HCV)‐related liver disease. The HTLV‐1 prevalence rate was 10 of 140 recipients (7.14%) and three of 140 donors (0.02%). In HCV‐related LDLT, graft and patient survival was worsened by HTLV‐1 infection in recipients (seven cases). The 1‐, 3‐, and 5‐year survival rates in the HCV/HTLV‐1‐co‐infected group were 67%, 32%, and 15%, respectively, and the corresponding rates in the HCV‐mono‐infected group were 80%, 67%, and 67%, respectively. Only the 5‐year survival rates were statistically significant (P = 0.04, log‐rank method). HTLV‐1 infection in recipients is also an important factor in predicting survival in HTLV‐1 endemic areas.
Estrogen is known to retard the development of atherosclerosis and to work in the brain, but the mechanism of hormonal action is completely unknown. We investigated the effect of estrogen on the ...activity of neuronal constitutive nitric oxide synthase (NNOS). A low concentration of estrogen (10(-10)(-7) M) enhanced the activity of homogenates of the cytosol fraction of rabbit cerebellums and also that of partially purified NNOS, and high dose (10(-6)(-5) M) attenuated them. The study using estrogen receptor antagonists, tamoxifen, clomiphene, and ICI182780 suggested that estrogen receptor did not relate significantly to those effects of 17 beta-estradiol. 17 alpha-estradiol or progesterone did not change significantly it in low doses, although moderately inhibited it in high doses. Estrogen enhanced the fluorescence of dansyl-calmodulin in low doses and attenuated it in high doses, suggesting that estrogen affects Ca(2+)-calmodulin directly. This study demonstrated that estrogen has a biphasic effect on the activity of NNOS through a Ca(2+)-calmodulin.
We clarified the influence of grounding resistance on the effectiveness of lightning protection for power distribution lines with a ground wire (GW) and surge arresters (SAs) by EMTP analysis and ...experiments. The results indicated that power distribution lines with both a GW and SAs can increase the lightning protection level against direct hits without lowering the grounding resistance compared with using only SAs. A cost reduction and the improvement of the electric supply reliability can be expected by exchanging part of the grounding cost with the installation of a lot of lightning protection devices on power distribution lines.
We examined the effect of dialyzing oxidized low-density lipoprotein (oLDL) against Krebs-Ringer solution, in the absence (yielding d-oLDL) or presence (yielding EDTA-oLDL) of ethylenediamine ...tetraacetic acid (EDTA), to investigate the mechanism that underlies the inhibition of endothelium-dependent relaxation (EDR) by o-LDL. Oxidation of LDL by exposure to Cu2+ resulted in the formation of a thiobarbituric acid-reacting substance (TBARS) and lipid hydroperoxide (LPO). At a concentration of 5 mg/dl, d-oLDL markedly attenuated EDR in the porcine coronary artery. Analysis of d-oLDL by gel filtration revealed that TBARS was ditributed in both the lipoprotein and the aqueous phases, whereas LPO was present only in the lipoprotein particles. Lysophosphatidylcholine (LPC), which has been suggested to be responsible for the impairment of EDR by oLDL, was present not only in the lipoprotein but also in the aqueous phase. However, EDR inhibitory activity was observed only in the oLDL particles, not in the aqueous phase. Almost all Cu2+ associated with the oLDL particles was removed by dialysis of oLDL against Krebs-Ringer solution containing EDTA. EDTA-oLDL or native LDL, at concentrations as high as 75 mg/dl, exerted only a moderate inhibitory action on EDR, Both TBARS and LPO in EDTA-oLDL were distributed only in the lipoprotein particles, not in the aqueous phase. These results demonstrate that the impairment of EDR by oLDL is related both to LPO and to transition metal ions such as Cu2+ associated with the lipoprotein particles, not to the amount of the TBARS or negative charge, and that factors other than LPC may affect EDR.
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