Effect of pentavalent inorganic arsenic salt on erythropoietin production and autophagy induction

Arsenic is abundant in the environment and takes the form of trivalent and pentavalent arsenic compounds. Arsenite has been reported to both promote and suppress erythropoietin (EPO) production and autophagy induction. EPO production is involved in hematopoiesis, and autophagy induction is involved in cytoprotection, both of which are thought to be cellular responses to arsenic stress. While there are reports that show the effects of EPO on autophagy induction, the relationship between EPO production and autophagy induction is unclear. Therefore, this study analyzed the effect of the pentavalent inorganic arsenic salt arsenate on EPO production in vitro and in vivo and EPO-induced autophagy in HepG2 cells. Exposure of HepG2 cells to low-concentration arsenate was observed to increase EPO production and induced autophagy. Moreover, a ROS scavenger suppressed the arsenate-induced increase in autophagy and EPO mRNA levels. Both EPO production and autophagy induction contributed to protection from arsenate-induced cytotoxic stress. HepG2 cells expressed the EPO receptor and production of EPO by HepG2 cells acted in an autoregulatory manner to suppress autophagy induction. In vivo administration of low-concentration arsenate to rats increased EPO mRNA levels in the liver and kidney. These results suggested that low-concentration arsenate promotes EPO production and autophagy induction in HepG2 cells, and the resultant EPO production contributes to cytoprotection of cultured cells via EPO receptor activation.

Synergistic effects of injection of bone marrow cells into both portal vein and bone marrow on tolerance induction in transplantation of allogeneic pancreatic islets

We have established a new method for allogeneic pancreatic islet (PI) transplantation: relatively low doses of irradiation followed by simultaneous transplantation of PIs and bone marrow cells (BMCs) via the portal vein (PV). In the present study, we have compared this method with intra-bone marrow (IBM)-bone marrow transplantation (BMT), and with a combination of both methods. Streptozotocin (STZ)-induced diabetic-recipient rats, Fischer 344 (F344, RT1A(l), RT1B(l)), were irradiated 1 day before transplantation. PIs of Brown Norway rats (BN, RT1A(n), RT1B(n)) were transplanted into the liver of the diabetic F344 rats via the PV. BMCs from BN rats were injected into the recipients' bone marrow (IBM), PV or intravenously (IV) or by a simultaneous combination of PV plus IBM (PV+IBM). We compared graft survival among the groups of '9 Gy+IBM'(10/10 accepted), '9 Gy+PV'(7/10 accepted), '9 Gy+IV'(0/7 accepted), '9 Gy+PV+IBM'(8/8 accepted), '8.5 Gy+IBM'(4/9 accepted), '8.5 Gy+PV'(0/7 accepted), '8.5 Gy+IV'(0/7 accepted), '8.5 Gy+PV+IBM'(9/12 accepted), '8 Gy+IBM'(2/10 accepted) and '8 Gy+PV+IBM'(2/8 accepted). As we reported previously, PV-BMT is more effective in inducing the acceptance of allogeneic PIs than IV-BMT. However, IBM-BMT requires less pretreatment than PV-BMT. (PV+IBM)-BMT was found to be the most effective in inducing the acceptance of allogeneic PIs. These results suggest that allogeneic PI-transplantation in conjunction with (PV+IBM)-BMT could become a viable strategy.

Relationship between the structure and cytotoxic activity of asterriquinone, an antitumor metabolite of Aspergillus terreus, and its alkyl ether derivatives

Asterriquinone (ARQ) is an antitumor metabolite of Aspergillus terreus IFO 6123. In this study we synthesized several ARQ alkyl ethers and studied their cytotoxic activity against mouse leukemia P388 cells. The dissociation constant was also similar among the ARQ monoalkyl ethers. There was a good correlation between the hydrophobicity of ARQ monoalkyl ethers estimated by high performance liquid chromatography and the intracellular content accumulated for 60 min. ARQ monoalkyl ethers were cytotoxic, but ARQ dimethyl ether was not, as previously reported. The cytotoxicity of the ARQ monoalkyl ether derivatives was increased with extension of the alkyl chain length. The cytotoxicity was closely correlated with the intracellular content. The strongest ARQ derivative, ARQ monohexyl ether (ARQHex), formed more DNA-interstrand cross-links in the cells than ARQ. After treatment of P388 cells with ARQ and ARQHex for 6 h, a nucleosomal ladder pattern, as well as the appearance of degraded DNA, observed by flow cytometry, indicated that these compounds caused cellular apoptosis. Moreover, ARQ and ARQHex accumulated in the cells at the G1 phase of the cell cycle. These results indicated that ARQ monoalkyl ethers increased cytotoxicity, according to their membrane permeability based on the hydrophobicity, and they caused apoptotic cell death, as did ARQ.

Mechanism of the cytotoxicity of asterriquinone, a metabolite of Aspergillus terreus

Asterriquinone (ARQ) is an antitumor metabolite of Aspergillus terreus IFO 6123. ARQ is a quinone compound and the mechanism of its antitumor action was compared with that of its analog ARQDMe which was dimethylated at the dihydroxy benzoquinone moiety, and adriamycin (ADR). The cytotoxicity of ARQ against P388 cells was less than that of ADR, and ARQDMe showed hardly any cytotoxicity. ARQ and ADR formed DNA-interstrand cross links (ISC) in P388 cells in a concentration while the ISC index by ARQDMe was very low even at 10 microM. P388 cells treated with ARQ and ADR for 18 hours showed, dose-dependently, nucleosomal ladder formation as well as the appearance of degraded DNA. Difference between the action of ARQ and ADR were observed by flow cytometric cell cycle analysis. ARQ caused the cells to accumulate at the G1 phase of the cell cycle, while use of ADR led to arrest in the G2/M phase. ARQDMe never caused apoptotic changes or cell cycle alterations. These results indicate that ARQ intercalates in the genomic DNA, causes G1 arrest, and leads to apoptotic cell death, this suggests that the dihydroxybenzoquinone moiety of the compound is essential to elicit these actions.

Four new metabolites of Aspergillus terreus

Four new metabolites (1-4) were isolated from mycelium of Aspergillus terreus IFO 6123 producing asterriquinone (ARQ). The structures of 1 and 2 were shown to be 3,6-bis[1-(1,1-dimethyl-2-propenyl)-1H-indol-3-yl]-furo[3,2-b]furan- 2,5-dione (asterridinone) and 2,5-bis[1-(1,1-dimethyl-2-propenyl)-1H-indol-3- yl]-3-acetoxy-6-hydroxy-2,5-cyclohexadiene-1,4-dione (ARQ monoacetate), respectively, by the chemical and spectral data. Compounds 3 and 4 were identified with known asterriquinone isomers, 2-[1-(1,1-dimethyl-2-propenyl)-1H-indol-3-yl]-5-[2-(3-methyl-2-butenyl)- 1H-indol-3-yl]-3,6-dihydroxy-2,5-cyclohexadiene-1,4-dione (isoARQ) and 2,5-bis[2-(3-methyl-2-butenyl)-1H-indol-3-yl]-3,6-dihydroxy- 2,5-cyclohexadiene-1,4-dione (neoARQ), respectively.

Diagnosis of right ventricular involvement in chronic inferior myocardial infarction by means of body surface QRS changes

ST segment elevation in right precordial leads is thought to be good predictor of right ventricular involvement in patients with acute inferior myocardial infarction. This view, however, is rapidly disappearing. Therefore, using QRS changes in body surface potential maps in the chronic phase, we have attempted to differentiate patients with or without right ventricular involvement. Thirty patients with chronic inferior myocardial infarction (2 or more months after onset) were studied, in whom 87 unipolar ECGs and right ventriculograms were recorded. The patients were then divided into three groups depending on the locations of their abnormal QRS potentials (-2SD area) exceeding the normal range (mean -2SD). In group A, the -2SD area was located predominantly on the right inferior chest, in group B on the left inferior chest, and in group N on both the right and left inferior chests equally. The results showed that group A had a lower right ventricular ejection fraction (RVEF) compared with group B (A, 40 +/- 7%; B, 53 +/- 10%; p less than .001), while there was no difference in left ventricular ejection fraction between the two groups (49 +/- 11% and 49 +/- 11%, respectively). Moreover, right ventricular asynergy occurred in 14 of the 18 patients (78%) of group A but in only one of the 10 patients (10%) of group B. Group N was presumed to be intermediate between groups A and B.(ABSTRACT TRUNCATED AT 250 WORDS)