Protective effect of 17beta-estradiol on ischemic acute renal failure through the PI3K/Akt/eNOS pathway.

Estrogens attenuate renal injury induced by ischemia/reperfusion (I/R), an effect that is related to nitric oxide production in the post-ischemic kidney. The compound 17beta-estradiol (E(2)-beta) acting via estrogen receptors (ERs) is known to activate endothelial nitric oxide synthase (eNOS) through the phosphatidylinositol-3 kinase (PI3K)/Akt pathway. We determined if this pathway contributes to the renoprotective effect of E(2)-beta in the uninephrectomized ischemia reperfusion rat model of acute renal injury. Treatment with E(2)-beta suppressed the I/R-induced increases in blood urea nitrogen, plasma creatinine, urine flow, and fractional excretion of sodium while augmenting creatinine clearance, renal blood flow, and urine osmolality, indicating attenuation of renal injury. Phosphorylation of Akt and eNOS protein was significantly increased 30-60 min after reperfusion in estradiol-treated compared to vehicle-treated rats. The protective effects of E(2)-beta and protein phosphorylation were reversed by the PI3K inhibitor wortmannin or the ER antagonist tamoxifen. Furthermore, the E(2)-beta-induced renoprotective effects were not seen in eNOS knockout mice with renal injury. We conclude that the E(2)-beta-induced renoprotective effect is due to activation of the PI3K/Akt pathway followed by increased eNOS phosphorylation in the post-ischemic kidney.

Pathophysiological role of proteasome-dependent proteolytic pathway in endothelin-1-related cardiovascular diseases.

A proteasome-dependent proteolytic pathway serves important functions in cell cycle control and transcriptional regulation; however, its pathophysiological role in cardiovascular diseases is still unclear. We have recently obtained evidence that proteasome inhibitors are capable of preventing the development of deoxycorticosterone acetate (DOCA)-salt-induced hypertension or hypertrophy and of ischemic acute renal failure (ARF). Beneficial effects of the proteasome inhibitors were accompanied by a decrease in endothelin-1 (ET-1) content in the aorta and kidney of DOCA-salt and ischemic ARF animals, respectively. In addition, there is evidence showing that the reduction of nuclear factor-kappaB (NF-kappaB) activation is involved in the mechanisms for suppressive effects of proteasome inhibitors on ET-1 gene transcription and the consequent decrease in ET-1 mRNA expression in the cultured vascular endothelial cells. These findings suggest that a proteasome-dependent proteolytic pathway has a crucial role in the pathogenesis of ET-1-related cardiovascular diseases, probably through the activation of NF-kappaB, and also that the use of proteasome inhibitors may be a novel approach to the treatment of cardiovascular diseases.

Effects of alpha-lipoic acid on deoxycorticosterone acetate-salt-induced hypertension in rats.

We investigated the potential of natural occurring antioxidant alpha-lipoic acid to prevent hypertension and hypertensive tissue injury induced by deoxycorticosterone acetate (DOCA) and salt in rats. Two weeks after the start of DOCA-salt treatment, the rats were given alpha-lipoic acid (10 or 100 mg/kg/day, s.c.) or its vehicle for 2 weeks. Uninephrectomized rats without DOCA-salt treatment served as sham-operated controls. In vehicle-treated DOCA-salt rats, systolic blood pressure increased markedly after 3-4 weeks. Daily administration of 100 mg/kg alpha-lipoic acid for 2 weeks suppressed the increase in systolic blood pressure, whereas 10 mg/kg alpha-lipoic acid did not affect the progression of DOCA-salt-induced hypertension. When the degree of vascular hypertrophy of the aorta was morphometrically evaluated at 4 weeks, there were significant increases in media cross-sectional area in vehicle-treated DOCA-salt rats compared with sham-operated rats. The development of vascular hypertrophy was markedly suppressed by alpha-lipoic acid at 100 mg/kg but not at 10 mg/kg. Histopathological examination of the kidney in vehicle-treated DOCA-salt rats revealed fibrinoid-like necrosis in glomeruli and thickening of small arteries. In these animals, creatinine clearance decreased, and fractional excretion of Na(+), urinary excretion of protein and N-acetyl-beta-glucosaminidase increased. Such renal lesions and dysfunctions were ameliorated in DOCA-salt rats given alpha-lipoic acid. In addition, a marked increase in endothelin-1 content in both the aorta and kidney was evident in vehicle-treated DOCA-salt rats compared with findings in sham-operated rats. Significant attenuation of this increase occurred in alpha-lipoic acid-treated DOCA-salt rats. These results suggest that administration of alpha-lipoic acid to DOCA-salt hypertensive rats lessens the increased blood pressure and protects against renal and vascular injuries, possibly through the suppression of renal and vascular endothelin-1 overproduction.

Preventive effect of lactacystin, a selective proteasome inhibitor, on ischemic acute renal failure in rats.

To elucidate the role of a proteasome-dependent proteolytic pathway in the pathogenesis of acute renal failure (ARF), we examined the effect of a selective proteasome inhibitor, lactacystin, on ARF induced by ischemia/reperfusion. Ischemic ARF was induced by clamping the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function in untreated ARF rats markedly decreased at 24 h after reperfusion. Intraperitoneal injection of lactacystin at a dose of 0.1 mg/kg before the occlusion tended to attenuate the deterioration of renal function. The higher dose of lactacystin (1 mg/kg) markedly attenuated the ischemia/reperfusion-induced renal dysfunction. Histopathological examination of the kidney of untreated ARF rats revealed severe lesions, such as tubular necrosis, proteinaceous casts in tubuli, and medullary congestion, all of which were markedly suppressed by the higher dose of lactacystin. In addition, endothelin (ET)-1 content in the kidney after the ischemia/reperfusion was significantly increased, being the maximum level at 6 h after the reperfusion, and this elevation was abolished by the higher dose of lactacystin. These results indicate that lactacystin prevents the development of ischemia/reperfusion-induced ARF, and the effect is accompanied by suppression of the enhanced ET-1 production in the kidney, thereby suggesting that a proteasome-dependent proteolytic pathway has a crucial role in the pathogenesis of ischemic ARF, possibly through the enhancement of ET-1 production in postischemic kidneys.

A proteasome inhibitor prevents vascular hypertrophy in deoxycorticosterone acetate-salt hypertensive rats.

1. In the present study, we investigated the potential of the proteasome inhibitor N-benzyloxycarbonyl-Ile-Glu(O-t-Bu)-Ala-leucinal (PSI) to prevent vascular hypertrophy induced by deoxycorticosterone acetate (DOCA) and salt in rats. 2. Vehicle (35% ethanol, 35% polyethylene glycol and 30% saline solution)-treated DOCA-salt rats developed marked hypertension at 4 weeks. Morphological studies on the rats given vehicle showed aortic hypertrophy, with a significant increase in wall thickness, wall area and wall-to-lumen ratio. A significant decrease in vascular wall hypertrophy was observed in PSI (3 mg/kg)-treated DOCA-salt rats. In addition, a marked increase in aortic endothelin (ET)-1 content was evident in vehicle-treated DOCA-salt rats compared with findings in sham-operated rats. A significant attenuation of this increase occurred in PSI-treated DOCA-salt rats. 3. These results indicate that PSI can prevent the vascular hypertrophy in DOCA-salt hypertensive rats and the effect is accompanied by suppression of ET-1 production in the aorta. We suggest that a proteasome-dependent proteolytic system has an important role in the development of vascular hypertrophy in cases of DOCA-salt-induced hypertension, possibly through the enhancement of ET-1 production in vascular tissues.

Dual-mode electrochromism switched by proton transfer: dynamic redox properties of bis(diarylmethylenium)-type dyes.

Upon oxidative dimerization of pale yellow Ar2C=CHPh 1 (Ar = 4-Me2NC6H4), deep blue 1,4-dication 2(2+) was obtained as a stable salt, which was transformed into 1 by reductive C-C bond fission; deprotonation of 2(2+) gave intense yellow diene 3, which was interconvertible with violet dication 4(2+) by two-electron transfer, thus exhibiting two distinct modes of electrochromism before and after proton transfer.

Proteasome inhibition attenuates renal endothelin-1 production and the development of ischemic acute renal failure in rats.

The objectives of this study were (1) to assess the role of a proteasome-dependent proteolytic pathway in the pathogenesis of acute renal failure (ARF) induced by ischemia-reperfusion, and (2) to determine the involvement of this proteolytic pathway in the enhanced production of renal endothelin-1 (ET-1) in this model of ARF. ARF was induced by clamping the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function parameters such as blood urea nitrogen, plasma creatinine, creatinine clearance, urine flow, urinary osmolality and fractional excretion of sodium were measured to test the effectiveness of drugs used. Renal function in untreated ARF rats markedly decreased at 24 h after reperfusion. In addition, a marked increase in renal ET-1 content was evident in the ARF rats, compared to the sham-operated rats. Intraperitoneal injection of a proteasome inhibitor (PSI), N-benzyloxycarbonyl-Ile-Glu(O-t-Bu)-Ala-leucinal, at a dose of 1 mg/kg, 1 h before the clamping, significantly attenuated the renal function impairment in the ischemic ARF rats, and the effect was accompanied by a decrease in renal ET-1 content. On the other hand, a calpain inhibitor, calpeptin, had little effect at the same dose. These results suggest that a proteasome-dependent proteolytic pathway is involved in the enhanced production of ET-1 in the kidney and the consequent renal functional damage in ischemic ARF.

Preparation, structure, and unique redox properties of mono-, bis-, and Tris(diarylmethylene)-1,3,5-trithianes and related compounds

A series of 1,3,5-trithianes 1-3 having diarylmethylene units were designed as novel electron donors giving highly colored cationic species upon oxidation. They were prepared along with the dithiane and dithiazine derivatives 4-6 by the reactions of lithiated heterocycles with diaryl ketones followed by dehydration. Voltammetric analyses indicate that a large structural change and/or transannular bonding are induced during their electrochemical oxidation. Mono(diarylmethylene) derivative 1a exhibits electrochromism with vivid change in color from faintly yellow to deep blue with concomitant rotation around the exocyclic bond. Both of the strongly colored salts obtained upon oxidation of 2,4-bis- and 2,4,6-tris(diarylmethylene)-1,3,5-trithianes (2aa and 3) consist of the dications with a 1,2,4-trithiane ring, suggesting the easy skeletal rearrangement of the transannular dications with a trithiabicylo[3.1.0]hexane ring. Upon reduction of these salts were obtained bright yellow 12 and 13, respectively, with high electron-donating properties due to the tetraarylbutadiene-type conjugation, thus giving another class of electrochromic compounds.

Syntheses of Acetylenic Oligophenylene Macrocycles Based on a Novel Dewar Benzene Building Block Approach.

A general synthetic approach to strained p-phenylene-based acetylenic macrocycles is described. A key feature in this approach is exploitation of Dewar benzene as an angular p-phenylene synthon. Thus, 1,4-acetal-bridged 2,5-dichloro(Dewar benzene) 5, prepared in four steps from dimethyl acetylenedicarboxylate and 1,2-dichloroethylene, is applied as such a building block in the syntheses of strained macrocycles 13 and anti-20. For the synthesis of 13, m-phenylene units are used as spacers and modified Eglington-Glaser coupling is applied for the macrocyclization step. For the synthesis of anti-20, on the other hand, o-phenylene units are used as spacers and Sonogashira coupling is applied for the macrocyclization step. Macrocycles 13 and anti-20 are characterized crystallographically, and their strained nature is reflected mainly in the deviation of the acetylene units from linearity; the C&tbd1;C-C angles range from 168.7(3) degrees to 179.9(3) degrees in 13 and from 168.0(5) degrees to 171.4(4) degrees in anti-20. Macrocycle 13 shows unique conformational property, namely, the p-phenylene units arranged in parallel in the rectangular framework rotate freely about the long axes, as evidenced by the (1)H NMR studies. Macrocycle anti-20 exhibits a Stokes shift of 179 nm, which is exceptionally large for phenylacetylene macrocycles, presumably owing to the characteristic stacking structure.

Kinetic stabilization of the [1.1]paracyclophane system: isolation and X-ray structural analysis of a [1.1]paracyclophane derivative and its interconversion with the transannular adduct.

Intentionally designed kinetic stabilization of the [1.1]paracyclophane skeleton has been achieved by multiple substitution of the aromatic rings with trimethylsilylmethyl and N,N-dimethyl-carbamoyl groups, which serve to shield the proximate bridgehead carbon atoms sterically from access by other reagents. The bis(Dewar benzene) precursor (1a) has been prepared in essentially the same manner as previous derivatives--starting from the photocycloaddition of 1,4-bis(trimethylsilyl)-2-butyne to octa-hydroindacene-1,5-dione--except for a few critical modifications described in the text. Substituted [1.1]paracyclophane (2a), photochemically generated from the precursor, is indefinitely stable at 50 degrees C and suffers decomposition only by 8 % after 2 h at 100 degrees C in degassed n-decane, demonstrating its greatly improved kinetic stability compared to previous [1.1]paracyclophanes. Since 2a undergoes efficient photochemical transformation into the transannular addition product 3a, irradiation of la tends to produce a mixture of products consisting mainly of 3a. Compound 3a, however, reverts thermally to 2a in a process of half life 40 min at 55 degrees C; the activation parameters for this process are deltaH(not equal to)= 21.1 +/- 0.8 kcalmol(-1) and deltaS(not equal to) = -10.5 +/- 2.6 cal K(-1)mol(-1). Thus, on heating 3a in benzene and cooling the resultant solution, 2a is obtained as orange-red crystals. X-ray crystallographic analysis of 2a reveals benzene rings bent to the highest degree ever reported for a paracyclophane, with their face-to-face arrangement in unusually close proximity. The shortest nonbonding interatomic distance is 2.376 A; less than the sum of the van der Waals radii by more than 1.0A. The generation of related substituted [1.1]paracyclophanes and their kinetic stabilities are also reported.

Different contributions of endothelin-A and endothelin-B receptors in the pathogenesis of deoxycorticosterone acetate-salt-induced hypertension in rats.

We investigated the involvement of actions mediated by endothelin-A (ETA) and endothelin-B (ETB) receptors in the pathogenesis of deoxycorticosterone acetate (DOCA)-salt-induced hypertension in rats. Two weeks after the start of DOCA-salt treatment, rats were given ABT-627 (10 [mg/kg]/d), a selective ETA receptor antagonist; A-192621 (30 [mg/kg]/d), a selective ETB receptor antagonist; or their vehicle for 2 weeks. Uninephrectomized rats without DOCA-salt treatment served as controls. Treatment with DOCA and salt for 2 weeks led to a mild but significant hypertension; in vehicle-treated DOCA-salt rats, systolic blood pressure increased markedly after 3 to 4 weeks. Daily administration of ABT-627 for 2 weeks almost abolished any further increases in blood pressure, whereas A-192621 did not affect the development of DOCA-salt-induced hypertension. When the degree of vascular hypertrophy of the aorta was histochemically evaluated at 4 weeks, there were significant increases in wall thickness, wall area, and wall-to-lumen ratio in vehicle-treated DOCA-salt rats compared with uninephrectomized control rats. The development of vascular hypertrophy was markedly suppressed by ABT-627. In contrast, treatment with A-192621 significantly exaggerated these vascular changes. In vehicle-treated DOCA-salt rats, renal blood flow and creatinine clearance decreased, and urinary excretion of protein, blood urea nitrogen, fractional excretion of sodium, and urinary N-acetyl-beta-glucosaminidase activity increased. Such damage was overcome by treatment with ABT-627 but not with A-192621; indeed, the latter agent led to worsening of the renal dysfunction. Histopathologic examination of the kidney in vehicle-treated DOCA-salt rats revealed tubular dilatation and atrophy as well as thickening of small arteries. Such damage was reduced in animals given ABT-627, whereas more severe histopathologic changes were observed in A-192621-treated animals. These results strongly support the view that ETA receptor-mediated action plays an important role in the pathogenesis of DOCA-salt-induced hypertension. On the other hand, it seems likely that the ETB receptor-mediated action protects against vascular and renal injuries in this model of hypertension. A selective ETA receptor antagonist is likely to be useful for treatment of subjects with mineralocorticoid-dependent hypertension, whereas ETB-selective antagonism alone is detrimental to such cases.

A proteasome inhibitor lessens the increased aortic endothelin-1 content in deoxycorticosterone acetate-salt hypertensive rats.

Deoxycorticosterone acetate (DOCA)-salt-treated rats developed marked hypertension after 4 weeks with an increase in aortic endothelin-1. Treatment of DOCA-salt hypertensive rats with a proteasome inhibitor, N-benzyloxycarbonyl-Ile-Glu(O-t-Bu)-Ala-leucinal, significantly reduced the elevation in systolic blood pressure and the effect was accompanied by a decrease in aortic endothelin- content. Thus, a proteasome-dependent proteolytic pathway appears to play an important role in the enhanced production of endothelin-1 in blood vessels and the consequent increase in blood pressure in this model of hypertension.

[An autopsy case of a gastric cancer associated with elevated AFP, CEA and CA19-9].

A 48-year-old male developed gastric cancer (Borrmann III) with lung and liver metastases. Laboratory examination revealed a markedly elevated AFP (24, 241 ng/ml), CEA (9739.8 ng/ml), and CA-19-9 (726U/ml). Nevertheless, he underwent a subtotal gastrectomy for the hemostasis of a bleeding malignant lesion. Histological examination showed a moderately differentiated adenocarcinoma. A PAP for an AFP and a CEA disclosed positive staining. In addition, An autopsy revealed metastases to the liver and lungs with a positive result of PAP for AFP and CEA. Further, CA19-9 also was confirmed weakly in these same tissues, histochemically. Therefore this gastric cancer was considered an AFP, CEA, and CA19-9-producing tumor. Gastric cancer with 3 elevated tumor markers in the same patient is rare and its mechanism may elucidate the origin of gastric cancer and the resulting differentiation in the foregut.