Vardenafil in men with stable statin therapy and dyslipidemia.

INTRODUCTION: Phosphodiesterase type-5 (PDE-5) inhibitors have previously been evaluated for their efficacy and safety in various clinical trials in men with erectile dysfunction (ED) with or without associated comorbidities. AIM: This is the first prospective, randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of a PDE-5 inhibitor (i.e., vardenafil) in an exclusive population of men with ED and dyslipidemia. MAIN OUTCOME MEASURES: Three coprimary efficacy measurements (Sexual Encounter Performance [SEP]2, SEP3, International Index of Erectile Function-Erectile Function [IIEF-EF] domain scores) were used to assess the differential effect of vardenafil vs. placebo in this patient population. Adverse events (AEs) safety data were obtained to compare safety outcomes. METHODS: This 12-week of randomized, double-blind, placebo-controlled study was conducted in 59 U.S. centers. Patients received either on-demand, flexible-dose vardenafil 10 mg (titrated to 5 mg or 20 mg based upon efficacy and safety) or placebo. RESULTS: Of the 712 patients screened and entered into the study, 395 were randomized. Baseline demographics for the intent-to-treat population included: mean age, 54.4 years (+/-7.5 standard deviation [SD]); 76% Caucasian; mean body mass index (BMI), 31.7 kg/m(2) (+/-12.7 SD); 47% past/present smoker; and 42% severe ED. Aside from dyslipidemia, other comorbidities included hypertension, 61%; obesity (i.e., BMI >/= 30), 51%; and type 1 or 2 diabetes, 40%. During the 12-week treatment period, the least squares (LS) adjusted mean success rates in patients on vardenafil vs. placebo were: SEP2, 79.09% vs. 51.92%; and SEP3, 66.69% vs. 33.83% (P < 0.001). The LS adjusted mean IIEF-EF domain score for week 12 using LOCF was 21.99 in patients on vardenafil therapy vs. 14.83 in those on placebo (P < 0.001). The most commonly encountered AEs were headache and nasal congestion. CONCLUSIONS: Vardenafil was demonstrated to be safe and effective for managing ED in men with ED and associated dyslipidemia. The results of this study support the role of expanded research on outcomes related to effective ED treatment and aggressive lipid control.

28. Embryonic and adult stem cell therapy.

Stem cells are characterized by the ability to remain undifferentiated and to self-renew. Embryonic stem cells derived from blastocysts are pluripotent (able to differentiate into many cell types). Adult stem cells, which were traditionally thought to be monopotent multipotent, or tissue restricted, have recently also been shown to have pluripotent properties. Adult bone marrow stem cells have been shown to be capable of differentiating into skeletal muscle, brain microglia and astroglia, and hepatocytes. Stem cell lines derived from both embryonic stem and embryonic germ cells (from the embryonic gonadal ridge) are pluripotent and capable of self-renewal for long periods. Therefore embryonic stem and germ cells have been widely investigated for their potential to cure diseases by repairing or replacing damaged cells and tissues. Studies in animal models have shown that transplantation of fetal, embryonic stem, or embryonic germ cells may be able to treat some chronic diseases. In this review, we highlight recent developments in the use of stem cells as therapeutic agents for three such diseases: Diabetes, Parkinson disease, and congestive heart failure. We also discuss the potential use of stem cells as gene therapy delivery cells and the scientific and ethical issues that arise with the use of human stem cells.

Crosstalk between BCR/ABL oncoprotein and CXCR4 signaling through a Src family kinase in human leukemia cells.

Stromal-derived factor (SDF)-1 and its G protein-coupled receptor, CXCR4, regulate stem/progenitor cell migration and retention in the marrow and are required for hematopoiesis. We show here an interaction between CXCR4 and the Src-related kinase, Lyn, in normal progenitors. We demonstrate that CXCR4-dependent stimulation of Lyn is associated with the activation of phosphatidylinositol 3-kinase (PI3-kinase). This chemokine signaling, which involves a Src-related kinase and PI3-kinase, appears to be a target for BCR/ABL, a fusion oncoprotein expressed only in leukemia cells. We show that the binding of phosphorylated BCR/ABL to Lyn results in the constitutive activation of Lyn and PI3-kinase, along with a total loss of responsiveness of these kinases to SDF-1 stimulation. Inhibition of BCR/ABL tyrosine kinase with STI571 restores Lyn responsiveness to SDF-1 signaling. Thus, BCR/ABL perturbs Lyn function through a tyrosine kinase-dependent mechanism. Accordingly, the blockade of Lyn tyrosine kinase inhibits both BCR/ABL-dependent and CXCR4-dependent cell movements. Our results demonstrate, for the first time, that Lyn-mediated pathological crosstalk exists between BCR/ABL and the CXCR4 pathway in leukemia cells, which disrupts chemokine signaling and chemotaxis, and increases the ability of immature cells to escape from the marrow. These results define a Src tyrosine kinases-dependent mechanism whereby BCR/ABL (and potentially other oncoproteins) dysregulates G protein-coupled receptor signaling and function of mammalian precursors.

Clustered DNA damages induced in human hematopoietic cells by low doses of ionizing radiation.

Ionizing radiation induces clusters of DNA damages--oxidized bases, abasic sites and strand breaks--on opposing strands within a few helical turns. Such damages have been postulated to be difficult to repair, as are double strand breaks (one type of cluster). We have shown that low doses of low and high linear energy transfer (LET) radiation induce such damage clusters in human cells. In human cells, DSB are about 30% of the total of complex damages, and the levels of DSBs and oxidized pyrimidine clusters are similar. The dose responses for cluster induction in cells can be described by a linear relationship, implying that even low doses of ionizing radiation can produce clustered damages. Studies are in progress to determine whether clusters can be produced by mechanisms other than ionizing radiation, as well as the levels of various cluster types formed by low and high LET radiation.