Stem cell defects in Philadelphia chromosome negative chronic myeloproliferative disorders: a phenotypic and molecular puzzle?

Philadelphia chromosome-negative chronic myeloproliferative disorders (Ph(-) CMPD) comprise a group of heterogenous haematological stem cell disorders. These diseases harbour a pathological bone marrow stem cell which overwhelms normal stem cells due to sustained and uncontrolled proliferation. By clonal evolution, acute leukaemia or bone marrow fibrosis evolve in a proportion of cases with as yet unknown underlying mechanisms. Previously, groundbreaking investigations in Ph(-) CMPD detected an acquired mutation in the Janus kinase 2 (JAK2) in the majority of patients with polycythaemia vera (PV) and in up to 50% of patients with essential thrombocythaemia (ET) and chronic idiopathic myelofibrosis (CIMF). Unlike the stem cell defect in Philadelphia chromosome-positive chronic myeloid leukaemia only a subfraction of clonally proliferating haematopoiesis may be affected by the JAK2 mutation. More recently, another mutation in the juxtamembrane domain of the thrombopoietin receptor Mpl was discovered in about 5% of patients with CIMF and ET. In accordance with the uncontrolled Abl kinase activity in Ph(+) chronic myloid leukaemia these mutations in Ph(-) CMPD apparently represent a key to unlock some of the as yet unknown basic molecular defects and this raises hope for an upcoming efficient targeted therapy. However, neither the JAK2(V617F) nor the Mpl(W515L/K) provide the initiating molecular events. Moreover, apart from distinction between reactive and neoplastic lesions, detection of these mutations does not allow a clear-cut discrimination between the particular subtypes. This review will focus on previous and recent findings in the field of molecular defects in Ph(-) CMPD.     

Herbal medicine as an auspicious therapeutic approach for the eradication of Helicobacter pylori infection: A concise review

Helicobacter pylori (H. pylori) causes gastric mucosa inflammation and gastric cancer mostly via several virulence factors. Induction of proinflammatory pathways plays a crucial role in chronic inflammation, gastric carcinoma, and H. pylori pathogenesis. Herbal medicines (HMs) are nontoxic, inexpensive, and mostly anti-inflammatory reminding meticulous emphasis on the elimination of H. pylori and gastric cancer. Several HM has exerted paramount anti-H. pylori traits. In addition, they exert anti-inflammatory effects through several cellular circuits such as inhibition of 5′-adenosine monophosphate-activated protein kinase, nuclear factor-κB, and activator protein-1 pathway activation leading to the inhibition of proinflammatory cytokines (interleukin 1α [IL-1α], IL-1β, IL-6, IL-8, IL-12, interferon γ, and tumor necrosis factor-α) expression. Furthermore, they inhibit nitrous oxide release and COX-2 and iNOS activity. The apoptosis induction in Th1 and Th17-polarized lymphocytes and M2-macrophagic polarization and STAT6 activation has also been exhibited. Thus, their exact consumable amount has not been revealed, and clinical trials are needed to achieve optimal concentration and their pharmacokinetics. In the aspect of bioavailability, solubility, absorption, and metabolism of herbal compounds, nanocarriers such as poly lactideco-glycolide-based loading and related formulations are helpful. Noticeably, combined therapies accompanied by probiotics can also be examined for better clearance of gastric mucosa. In addition, downregulation of inflammatory microRNAs (miRNAs) by HMs and upregulation of those anti-inflammatory miRNAs is proposed to protect the gastric mucosa. Thus there is anticipation that in near future HM-based formulations and proper delivery systems are possibly applicable against gastric cancer or other ailments because of H. pylori.     

Antibody–drug conjugates (ADCs) for cancer therapy: Strategies,challenges, and successes

Targeted delivery of therapeutic molecules into cancer cells is considered as a promising strategy to tackle cancer. Antibody–drug conjugates (ADCs), in which a monoclonal antibody (mAb) is conjugated to biologically active drugs through chemical linkers, have emerged as a promising class of anticancer treatment agents, being one of the fastest growing fields in cancer therapy. The failure of early ADCs led researchers to explore strategies to develop more effective and improved ADCs with lower levels of unconjugated mAbs and more-stable linkers between the drug and the antibody, which show improved pharmacokinetic properties, therapeutic indexes, and safety profiles. Such improvements resulted in the US Food and Drug Administration approvals of brentuximab vedotin, trastuzumab emtansine, and, more recently, inotuzumab ozogamicin. In addition, recent clinical outcomes have sparked additional interest, which leads to the dramatically increased number of ADCs in clinical development. The present review explores ADCs, their main characteristics, and new research developments, as well as discusses strategies for the selection of the most appropriate target antigens, mAbs, cytotoxic drugs, linkers, and conjugation chemistries.     

Thrombospondin-1 expression and modulation of Wnt and hippo signaling pathways during the early phase of Trypanosoma cruzi infection of heart endothelial cells

The protozoan parasite, Trypanosoma cruzi, causes severe morbidity and mortality in afflicted individuals. Approximately 30% of T. cruzi infected individuals present with cardiac pathology. The invasive forms of the parasite are carried in the vascular system to infect other cells of the body. During transportation, the molecular mechanisms by which the parasite signals and interact with host endothelial cells (EC) especially heart endothelium is currently unknown. The parasite increases host thrombospondin-1 (TSP1) expression and activates the Wnt/β-catenin and hippo signaling pathways during the early phase of infection. The links between TSP1 and activation of the signaling pathways and their impact on parasite infectivity during the early phase of infection remain unknown. To elucidate the significance of TSP1 function in YAP/β-catenin colocalization and how they impact parasite infectivity during the early phase of infection, we challenged mouse heart endothelial cells (MHEC) from wild type (WT) and TSP1 knockout mice with T. cruzi and evaluated Wnt signaling, YAP/β-catenin crosstalk, and how they affect parasite infection. We found that in the absence of TSP1, the parasite induced the expression of Wnt-5a to a maximum at 2 h (1.73±0.13), P< 0.001 and enhanced the level of phosphorylated glycogen synthase kinase 3β at the same time point (2.99±0.24), P<0.001. In WT MHEC, the levels of Wnt-5a were toned down and the level of p-GSK-3β was lowest at 2 h (0.47±0.06), P< 0.01 compared to uninfected control. This was accompanied by a continuous significant increase in the nuclear colocalization of β-catenin/YAP in TSP1 KO MHEC with a maximum Pearson correlation coefficient of (0.67±0.02), P< 0.05 at 6 h. In WT MHEC, the nuclear colocalization of β-catenin/YAP remained steady and showed a reduction at 6 h (0.29±0.007), P< 0.05. These results indicate that TSP1 plays an important role in regulating β-catenin/YAP colocalization during the early phase of T. cruzi infection. Importantly, dysregulation of this crosstalk by pre-incubation of WT MHEC with a β-catenin inhibitor, endo-IWR 1, dramatically reduced the level of infection of WT MHEC. Parasite infectivity of inhibitor treated WT MHEC was similar to the level of infection of TSP1 KO MHEC. These results indicate that the β-catenin pathway induced by the parasite and regulated by TSP1 during the early phase of T. cruzi infection is an important potential therapeutic target, which can be explored for the prophylactic prevention of T. cruzi infection.     

Liquid chromatographic assay for a butenolide endothelin antagonist (PD 156707) in plasma

A sensitive and selective liquid chromatographic assay for determining the non-peptide endothelin A receptor antagonist PD 156707 (I) in rat plasma has been developed and validated. The analyte was isolated from matrix by solid-phase extraction. Liquid chromatographic separation was achieved isocratically ona 3.2 mm I.D., ODS column with a mobile hase of acetonitrile-ammonium phosphate (50 mM, pH 3.5) (44:56, v/v). Column effluent was monitored fluorometrically. Peak-height ratios (analyte/IS) were proportional to I concentrations in rat plasma from 25 to 1000 ng/ml. Assay precision and accuracy for I, based on quality controls, was 9.5% relative standard deviation, with relative error of ±6.5%. The quantitation limit was 25 ng/ml for a 200-μl sample aliquot.     

Comparative studies of chloroplastic and nuclear DNA repair abilities after ultraviolet irradiation of Euglena gracilis

Summary Studies of nuclear and chloroplastic-DNA repair after ultraviolet irradiation of Euglena gracilis show that photoreactivation is very efficient at both the nuclear and chloroplastic level. Liquid-holding or split-dose experiments and treatment with caffeine reveal, furthermore, that dark-repair is very efficient in nuclear DNA but not in chloroplastic DNA (ctDNA). The possibility of a chloroplastic dark-repair of restricted efficiency is discussed.Determination of chloroplastic DNA content by reassociation kinetics indicates that an important degradation follows UV irradiation during liquid holding in the dark.     

Linear and nonlinear relationships between neuronal activity, oxygen metabolism, and hemodynamic responses

We investigated the relationship between neuronal activity, oxygen metabolism, and hemodynamic responses in rat somatosensory cortex with simultaneous optical intrinsic signal imaging and spectroscopy, laser Doppler flowmetry, and local field potential recordings. Changes in cerebral oxygen consumption increased linearly with synaptic activity but with a threshold effect consistent with the existence of a tissue oxygen buffer. Modeling analysis demonstrated that the coupling between neuronal activity and hemodynamic response magnitude may appear linear over a narrow range but incorporates nonlinear effects that are better described by a threshold or power law relationship. These results indicate that caution is required in the interpretation of perfusion-based indicators of brain activity, such as functional magnetic resonance imaging (fMRI), and may help to refine quantitative models of neurovascular coupling.     

The role of the CD134-CD134 ligand costimulatory pathway in alloimmune responses in vivo

The CD134-CD134 ligand (CD134L) costimulatory pathway has been shown to be critical for both T and B cell activation; however, its role in regulating the alloimmune response remains unexplored. Furthermore, its interactions with other costimulatory pathways and immunosuppressive agents are unclear. We investigated the effect of CD134-CD134L pathway blockade on allograft rejection in fully MHC-mismatched rat cardiac and skin transplantation models. CD134L blockade alone did not prolong graft survival compared with that of untreated recipients, and in combination with donor-specific transfusion, cyclosporine, or rapamycin, was less effective than B7 blockade in prolonging allograft survival. However, in combination with B7 blockade, long-term allograft survival was achieved in all recipients (>200 days). Moreover, this was synergistic in reducing the frequency of IFN-gamma-producing alloreactive lymphocytes and inhibiting the generation of activated/effector lymphocytes. Most impressively, this combination prevented rejection in a presensitized model using adoptive transfer of primed lymphocytes into athymic heart transplant recipients. In comparison to untreated recipients (mean survival time (MST): 5.3 +/- 0.5 days), anti-CD134L mAb alone modestly prolonged allograft survival (MST: 14 +/- 2.8 days) as did CTLA4Ig (MST: 21.5 +/- 1.7 days), but all grafts were rejected within 24 days. Importantly, combined blockade further and significantly prolonged allograft survival (MST: 75.3 +/- 12.7 days) and prevented the expansion and/or persistence of primed/effector alloreactive T cells. Our data suggest that CD134-CD134L is a critical pathway in alloimmune responses, especially recall/primed responses, and is synergistic with CD28-B7 in mediating T cell effector responses during allograft rejection. Understanding the mechanisms of collaboration between these different pathways is important for the development of novel strategies to promote long-term allograft survival.