MnSOD overexpression prevents liver mitochondrial DNA depletion after an alcohol binge but worsens this effect after prolonged alcohol consumption in mice

Both acute and chronic alcohol consumption increase reactive oxygen species (ROS) formation and lipid peroxidation, whose products damage hepatic mitochondrial DNA (mtDNA). To test whether manganese superoxide dismutase (MnSOD) overexpression modulates acute and chronic alcohol-induced mtDNA lesions, transgenic MnSOD-overexpressing (TgMnSOD(+++)) mice and wild-type (WT) mice were treated by alcohol, either chronically (7 weeks in drinking water) or acutely (single intragastric dose of 5 g/kg). Acute alcohol administration increased mitochondrial ROS formation, decreased mitochondrial glutathione, depleted and damaged mtDNA, durably increased inducible nitric oxide synthase (NOS) expression, plasma nitrites/nitrates and the nitration of tyrosine residues in complex V proteins and decreased complex V activity in WT mice. These effects were prevented in TgMnSOD(+++) mice. In acutely alcoholized WT mice, mtDNA depletion was prevented by tempol, a superoxide scavenger, L-NAME and 1400W, two NOS inhibitors, or uric acid, a peroxynitrite scavenger. In contrast, chronic alcohol consumption decreased cytosolic glutathione and increased hepatic iron, lipid peroxidation products and respiratory complex I protein carbonyls only in ethanol-treated TgMnSOD(+++) mice but not in WT mice. In chronic ethanol-fed TgMnSOD(+++) mice, but not WT mice, mtDNA was damaged and depleted, and the iron chelator, deferoxamine (DFO), prevented this effect. In conclusion, MnSOD overexpression prevents mtDNA depletion after an acute alcohol binge but aggravates this effect after prolonged alcohol consumption, which selectively triggers iron accumulation in TgMnSOD(+++) mice but not in WT mice. In the model of acute alcohol binge, the protective effects of MnSOD, tempol, NOS inhibitors and uric acid suggested a role of the superoxide anion reacting with NO to form mtDNA-damaging peroxynitrite. In the model of prolonged ethanol consumption, the protective effects of DFO suggested the role of iron reacting with hydrogen peroxide to form mtDNA-damaging hydroxyl radical.     

Red blood cell generation from human induced pluripotent stem cells: perspectives for transfusion medicine

Background

Ex vivo manufacture of red blood cells from stem cells is a potential means to ensure an adequate and safe supply of blood cell products. Advances in somatic cell reprogramming of human induced pluripotent stem cells have opened the door to generating specific cells for cell therapy. Human induced pluripotent stem cells represent a potentially unlimited source of stem cells for erythroid generation for transfusion medicine.

Design and Methods

We characterized the erythroid differentiation and maturation of human induced pluripotent stem cell lines obtained from human fetal (IMR90) and adult fibroblasts (FD-136) compared to those of a human embryonic stem cell line (H1). Our protocol comprises two steps: (i) differentiation of human induced pluripotent stem cells by formation of embryoid bodies with indispensable conditioning in the presence of cytokines and human plasma to obtain early erythroid commitment, and (ii) differentiation/maturation to the stage of cultured red blood cells in the presence of cytokines. The protocol dispenses with major constraints such as an obligatory passage through a hematopoietic progenitor, co-culture on a cellular stroma and use of proteins of animal origin.

Results

We report for the first time the complete differentiation of human induced pluripotent stem cells into definitive erythrocytes capable of maturation up to enucleated red blood cells containing fetal hemoglobin in a functional tetrameric form.

Conclusions

Red blood cells generated from human induced pluripotent stem cells pave the way for future development of allogeneic transfusion products. This could be done by banking a very limited number of red cell phenotype combinations enabling the safe transfusion of a great number of immunized patients.     

Loss of the Y chromosome in Philadelphia-positive cells predicts a poor response of chronic myeloid leukemia patients to imatinib mesylate therapy

In chronic myeloid leukemia (CML), cytogenetic abnormalities found in addition to the t(9;22) translocation may impact the response to therapy. Loss of the Y chromosome is generally overlooked in this context, owing to its relatively frequent occurrence in healthy elderly patients. In this multicenter retrospective study, the outcome after imatinib treatment of 30 CML patients with karyotype showing Y chromosome loss (Y−) was compared to 30 Y+ control males diagnosed and treated at the same time in the same institutions. Y− patients had significantly delayed cytogenetic and molecular responses, lower event-free survival and shorter overall survival than Y+ patients. The negative impact of this abnormality was particularly marked when it occurred in a sub-clone (clonal evolution) rather than in all mitoses. These data indicate that loss of the Y chromosome should be taken into account in the prognostic evaluation of chronic myelogenous leukemia patients.     

Novel anticoagulants for stroke prevention in atrial fibrillation: current clinical evidence and future developments

Atrial fibrillation (AF) is the most common cardiac rhythm disorder and a major risk factor for ischemic stroke. Antithrombotic therapy using aspirin or vitamin K antagonists (VKA) is currently prescribed for prevention for ischemic stroke in patients with AF. A narrow therapeutic range and the need of regular monitoring of its anticoagulatory effect impair effectiveness and safety of VKA, causing a need for alternative anticoagulant drugs. Recently developed anticoagulants include direct thrombin antagonists such as dabigatran or factor Xa inhibitors such as rivaroxaban, apixaban, betrixaban, and edoxaban. Currently, data from a phase III clinical trial are available for dabigatran only, which show the direct thrombin antagonist to be at least noninferior in efficacy to VKA for the prevention of stroke and systemic embolism in patients with AF. This review focuses on current advances in the development of directly acting oral anticoagulant drugs and their potential to replace the VKA class of drugs in patients with AF.     

Effect of hysterectomy on colonoscopy completion rate

BACKGROUND:

Several studies show that colonoscopies are technically more difficult to perform in women than men, especially in women who have undergone abdominal and gynecological surgeries. A review of the literature indicates an increased rate of noncompletion of colonoscopies in most cases; however, no studies have investigated the procedural complication rate, sedation requirements and perception of pain in colonoscopies.

OBJECTIVE:

To determine whether women who have undergone a previous hysterectomy have a higher noncompletion rate when undergoing a colonoscopy, and to assess whether there is a higher percentage of complications. Furthermore, the present study also aimed to ascertain whether these women required more sedation and whether their perception of pain is greater than that of women who did not undergo previous abdominal surgeries.

METHODS:

The present study was a prospective cohort study of women, 45 to 80 years of age, who underwent colonoscopy (n=508). A total of 229 patients were eligible for the study; they completed a questionnaire, and were subsequently divided into control and hysterectomy groups. Gastroenterologists performed all procedures. After colonoscopy, the patient and endoscopist completed a pain perception questionnaire. Cecal intubation rates were also recorded.

RESULTS:

No significant difference for cecal intubation rates were detected between the two groups (95.7% and 98.7% in hysterectomy and control groups, respectively; P=0.176). The crude OR for the success rate was 0.29 (95% CI 0.05 to 1.90). There was no significant difference between groups regarding sedation or the type of colonoscope. No correlation between the gastroenterologists’ evaluation of pain and patients’ pain was observed.

CONCLUSION:

Hysterectomy did not significantly diminish the cecal intubation rate, and there was no detectable difference in pain perception or sedative dose. Colonoscopy remains an excellent screening and diagnostic tool for all women.     

The CLEAR Study: A 5-day, 3-g Loading Dose of Mycophenolate Mofetil versus Standard 2-g Dosing in Renal Transplantation

Background and objectives: Adequate early mycophenolic acid (MPA) exposure is associated with lower rates of acute rejection in renal transplantation. The aim of this randomized controlled trial was to determine if higher initial mycophenolate mofetil (MMF) doses increased the proportion of patients reaching therapeutic MPA levels (30 to 60 mg·h/L) by day 5.Design, setting, participants, & measurements: De novo renal transplant patients were randomized to receive intensified dosing of MMF (1.5 g twice daily on days 1 to 5, then 1.0 g twice daily) or standard dosing (1.0 g twice daily). All recipients received tacrolimus and prednisone. Full MPA areas under the curve (AUCs) were completed on days 3 and 5, whereas a limited sampling strategy was utilized at four subsequent time points.Results: At day 5, 47.5% of the MMF 3-g arm achieved the MPA therapeutic window versus 54.4% of the MMF 2-g arm. However, MPA AUC levels were significantly higher in the 3-g arm at day 3 and 5. This resulted in a trend for fewer treated acute rejections at 6 months. Significantly more acute rejections (treated, biopsy-proven including and excluding borderline) occurred in patients with MPA AUC levels <30 mg·h/L compared with those ≥30 mg·h/L at day 5. No significant differences were seen in common adverse events.Conclusions: A limited intensified dose of MMF increased early MPA exposure and was well tolerated. Further studies are required to determine whether limited intensified MMF dosing can reduce acute rejection.Mycophenolate mofetil (MMF, CellCept^®) is an effective immunosuppressant and a key component of the immunosuppression regimen in most renal allograft recipients (1,2). A recent review and preliminary meta-analysis showed that overall graft survival is better with MMF compared with azathioprine when administered with calcineurin inhibitors (3,4). Traditionally, MMF is administered as a fixed dose without therapeutic drug monitoring (TDM). It remains unclear what role TDM of MMF has in improving graft and patient outcomes.There is a growing body of evidence supporting the utility of TDM. The drug has a large interpatient variability, with a 6-fold variation for a fixed daily dose (5). Van Gelder and his colleagues demonstrated a clear dose-effect relationship between acute rejection and 12-hour mycophenolic acid (MPA) area under the curve (AUC) exposures (6). MPA AUC values between 30 and 60 mg·h/L are proposed to be the target therapeutic window for patients treated with cyclosporine and prednisone (5). However, nearly 50% of cyclosporine-treated subjects are below the therapeutic target within the first week when administered the standard MMF dose of 2 g daily posttransplantation (7). More recently, a randomized controlled trial demonstrated that a concentration-controlled arm (dosed to achieve a mean exposure of 45 mg·h/L) resulted in significantly less rejection as compared with a standard-dosed arm (8).However, TDM is problematic given the poor correlation with any convenient single point concentration and AUC (5). Furthermore, there is some evidence that early exposure is important, with day-3 values being better predictors of acute rejection as compared with later values (7,9). Accordingly, clinicians would need to monitor exposure early and aim to intensify treatment within the first 3 days. Nonsteady-state conditions and the requirement for rapid turnaround times make TDM problematic in the early posttransplantation period. Alternatively, higher initial doses could either be given during the early critical period or until TDM can be performed. However, the safety profile of this approach is unknown. In addition, tacrolimus is now the most commonly used calcineurin inhibitor in the United States and there is limited information on MMF exposure when used in combination with tacrolimus (2,10).This study compared the ability of early, intensified, but limited-duration MMF dosing to increase the number of patients adequately exposed to MPA within the first week posttransplantation as compared with standard dosing in renal transplant recipients treated with tacrolimus.     

Lopinavir/ritonavir population pharmacokinetics in neonates and infants

AIMS

Because of immature hepatic metabolism, lopinavir could present specific pharmacokinetics in the first weeks of life. We aimed at determining the optimal dosing regimen in neonates and infants weighing 1 to 10.5 kg.

METHODS

Lopinavir/ritonavir (LPV/r) pharmacokinetics were studied in 96 infants using a population approach.

RESULTS

A one-compartment model described LPV/r pharmacokinetics. Normalized to a 70 kg adult using allometry, clearance (CL/F) and distribution volume (V/F) estimates were 5.87 l h⁻¹ 70 kg⁻¹ and 91.7 l 70 kg⁻¹. The relative bioavailabilty, F, increased with post-menstrual age (PMA) and reached 50% of the adult value at 39.7 weeks.

CONCLUSIONS

Size and PMA explained some CL/F and V/F variability in neonates/infants. Based upon trough concentration limitations, suggested LPV/r dosing regimens were 40 mg 12 h⁻¹, 80 mg 12 h⁻¹ and 120 mg 12 h⁻¹ in the 1–2 kg, 2–6 kg and 6–10 kg group, respectively.     

The Phage Therapy Paradigm: Prêt-à-Porter or Sur-mesure?

Pharmaceutical Research -