Elevation of arterial potassium during acute systemic hypoxia is abolished by alkalosis

BACKGROUND: Small elevations in plasma potassium evoke vasodilation in the peripheral circulation. Systemic hypoxia elevates arterial potassium and also modifies arterial pH. AIMS: We examined the interaction between pH and potassium in blood during systemic hypoxia and the effect of pH on the uptake/release of potassium in the peripheral tissues. METHODS: Anesthetized dogs were ventilated with air plus oxygen for normoxia or air plus nitrogen for hypoxia. Some animals received intravenous sodium bicarbonate to elevate pH by 0.1 units. Arterial plasma potassium concentration was measured in normoxia and hypoxia. A rat gracilis muscle was perfused with normoxic Krebs buffer and the potassium content of the venous outflow was compared during perfusion at pH 7.4, 6.8, or 7.8. RESULTS: In dogs with an arterial pH of 7.40-7.45, systemic hypoxia elevated the arterial potassium by 1 mmol/L. An arterial pH of 7.55 did not alter the basal potassium concentration, but it abolished the hypoxia-induced increase. In rat muscle, reduction of the perfusate pH from 7.4 to 6.8 reduced arterial perfusion pressure from 8.73 to 7.32 kPa and venous potassium from 6.6 to 5.2 mM. Elevation of perfusate pH to 7.8 decreased the arterial perfusion pressure from 8.44 to 6.95 kPa but did not affect venous potassium. CONCLUSIONS: The hypoxia-induced elevation of arterial potassium is abolished by increasing the pH to 7.55. This is not due to enhanced potassium uptake into peripheral tissues at high pH. Red blood cells are suggested as the most likely source of the potassium released in hypoxia.     

ILK as a potential marker gene to ascertain specific adenocarcinoma cell mRNA isolation from frozen prostate biopsy tissue sections

A major technical challenge related to gene expression profiling of tissue samples is the difficulty of procuring selected cell populations from tissues that by nature are heterogeneous, such as prostate tissue. In this study we have examined the expression of integrin-linked kinase (ILK) mRNA in prostate adenocarcinoma cells versus normal prostate epithelial cells in order to determine whether ILK could be used as a reference marker gene for prostate adenocarcinoma cell mRNA isolation. Using laser microdissection (LMD) technology and real-time PCR, together with immunohistochemistry, we have analyzed ILK mRNA expression in epithelial cells isolated from frozen prostate biopsy specimens as well as 4 prostate cell lines (RWPE-1, LNCaP, PC-3 and DU 145) and correlated ILK mRNA expression with ILK protein expression. We demonstrate that quantitative upregulation of ILK mRNA expression in prostate epithelial cells derived from prostate tissue correlated with ILK protein expression and with the histopathology diagnosis of prostate adenocarcinoma. We further show that the level of ILK overexpression was directly influenced by the method used to isolate prostate adenocarcinoma cells (bulk tissue versus LMD dissected cells). These data provide evidence that ILK mRNA is quantitatively upregulated in prostate adenocarcinoma cells versus normal epithelial cells and is therefore a useful internal reference gene marker to evaluate the quality of prostate adenocarcinoma cell derived mRNA used for large scale prostate cancer cDNA gene profiling.     

Anti-angiogenic effects and regression of localized murine AML produced by anti-VEGF and anti-Flk-1 antibodies

Reducing the blood supply of tumors is one modality to combat cancer. The objective of this study was to evaluate such an approach in the treatment of localized murine AML (acute myelogenous leukemia). For this purpose we designed an experimental model in which leukemic cells were embedded in 1% agar discs before subcutaneous implantation in C57Bl female mice. The C-1498 AML cell line (Frederick Inst., NCI, MD, USA) was used. Thirty experimental mice received on alternate days injections of 5 x 2.5 microg anti-VEGF (vascular endothelial growth factor) and 5 x 2.5 microg anti-Flk-1 (VEGFR2) antibodies to the site of cell implantation over a period of 10 d. Fifteen control mice received daily PBS injections. All mice were sacrificed 16 d after AML implantation. Of the 30 experimental animals, macroscopic examination showed in 21 animals (70%) small sized, pale tumors (0.5 g); in six mice (20%) the tumors were replaced completely by necrotic tissue, while in three mice (10%), there were large (2.5 g), highly vascularized tumors. In all 15 control mice large highly vascularized tumors were seen. A separate group of mice was studied for total survival following AML implantation. While 12 mice in the control group not treated with antibodies survived for 16 d post-implantation, survival was prolonged in 15 antibody treated mice by approximate 30 d to a total survival time of 48 d. Tumor specimens were processed for histology, immunohistochemistry (IHC) for CD31 endothelial cell antigen, and tube-like formation assay. The small, pale tumors of antibody treated animals consisted of degenerate hyaline material with remnant nests of leukemic cells, whereas large tumors showed sheets of leukemic cells and numerous blood vessels. Specimens processed for CD31 antigen showed scarce or absence of blood vessels in the small, pale tumors in contrast to intensive staining from a rich network of blood vessels in the large, highly vascularized tumors. Tube-like formation assays disclosed rudimentary Grade 1 endothelial cell tubes in the small, pale tumors as opposed to polygonal Grade 4 tube formation in control animals. In conclusion, this murine model of localized AML allows assessment of anti-angiogenic tumor regression. Anti-angiogenic antibodies against VEGF and Flk-1 have therapeutic effects in murine AML.     

High-dose therapy with autologous stem cell transplantation in first response in mantle cell lymphoma

We retrospectively investigated the outcome of 30 newly diagnosed patients with mantle cell lymphoma treated with high-dose therapy and autologous stem cell transplantation in first response. With a median follow-up of 55 months, the 5-year overall-survival is 62%, the 5-year progression-free-survival is 40% and no secondary malignancy has occurred.     

Effects of armagnac or vodka on platelet aggregation in healthy volunteers: a randomized controlled clinical trial

BACKGROUND: Cardiovascular mortality is especially low in southwest France (the French Paradox). In previous experimental studies, we found that alcohol-free extracts of armagnac could inhibit human platelet function in vitro and experimental thrombosis in vivo. To test the possible relevance of these findings, we tested the effects of daily use of small quantities of armagnac against same alcohol strength, polyphenol-free vodka in healthy volunteers. METHOD: Randomized controlled trial comparing 5-year old armagnac (30 ml/day for 2 weeks) to same alcoholic strength vodka, in 20 healthy volunteers, on platelet aggregation induced by ADP, collagen, and thrombin, as well as bleeding time, partial thromboplastin time (pTT), and plasma lipids during and after consumption. Platelet testing was done blind. RESULTS: After 14 days, ADP-induced platelet aggregation was inhibited more in armagnac (-31+/-3.2% compared to pretreatment values, p<.01) than in vodka (-11.0+/-6.8%, NS) users (p<.05, armagnac vs. vodka). A rebound increase of aggregation was found 2 weeks later in vodka but not in armagnac users. The same pattern was found for thrombin-induced aggregation, including post-treatment rebound. No effect was found on collagen-induced aggregation, bleeding time, pTT, or plasma lipids. CONCLUSION: The chronic ingestion of moderate quantities of armagnac modified platelet aggregation to ADP in healthy volunteers. The difference with the effects of same alcohol degree vodka is in favour of an effect of the nonalcoholic fraction in the effects of armagnac, rather than just alcohol. All spirits may not be equal for cardioprotection.