Recombinant human interleukin-11 stimulates multilineage hematopoietic recovery in mice after a myelosuppressive regimen of sublethal irradiation and carboplatin

Interleukin-11 (IL-11) is a novel multifunctional hematopoietic cytokine capable of stimulating cells of the myeloid, lymphoid, erythroid, and megakaryocytic lineages in vitro. We have tested the pleiotropic properties of this cytokine on the hematopoietic recovery of mice after a combined regimen of sublethal irradiation and carboplatin administration. This regimen results in severe myelosuppression, characterized by a prolonged period of thrombocytopenia and severe anemia. Administration of recombinant human IL-11 (rhIL-11; 250 micrograms/kg/d) had multilineage effects on bone marrow and spleen hematopoietic activity, increasing the number of megakaryocyte, erythroid, granulocyte, and macrophage progenitors compared with the vehicle-treated controls. This was reflected in the peripheral circulation by a reduction of both the platelet and hematocrit nadirs and a significantly reduced period of thrombocytopenia and anemia in the rhIL-11-treated mice. The results from this study support the broad spectrum of biologic activities that have been attributed to rhIL-11 in vitro and suggest that this cytokine may be an effective agent in the treatment of myelosuppression associated with cancer chemotherapy and bone marrow transplantation.     

Abnormal function of the bone marrow microenvironment in chronic myelogenous leukemia: role of malignant stromal macrophages

The bone marrow microenvironment supports and regulates the proliferation and differentiation of hematopoietic cells. Dysregulated hematopoiesis in chronic myelogenous leukemia (CML) is caused, at least in part, by abnormalities in CML hematopoietic progenitors leading to altered interactions with the marrow microenvironment. The role of the microenvironment itself in CML has not been well characterized. We examined the capacity of CML stroma to support the growth of long-term culture-initiating cells (LTC-IC) obtained from normal and CML marrow. The growth of normal LTC-IC on CML stroma was significantly reduced compared with normal stroma. This did not appear to be related to abnormal production of soluble factors by CML stroma because normal LTC- IC grew equally well in Transwells above CML stroma as in Transwells above normal stroma. In addition, CML and normal stromal supernatants contained similar quantities of both growth-stimulatory (granulocyte colony-stimulating factor (CSF), interleukin-6, stem cell factor, granulocyte-macrophage CSF, and interleukin-1 beta) and growth- inhibitory cytokines (transforming growth factor-beta, macrophage inflammatory protein-1 alpha, and tumor necrosis factor-alpha). The relative proportion of different cell types in CML and normal stroma was similar. However, polymerase chain reaction and fluorescence in situ hybridization studies showed the presence of bcr-abl-positivo cells in CML stroma, which were CD14+ stromal macrophages. To assess the effect of these malignant macrophages on stromal function, CML and normal stromal cells were separated by fluorescence-activated cell sorting into stromal mesenchymal cell (CD14-) and macrophage (CD14+) populations. CML and normal CD14- cells supported the growth of normal LTC-IC equally well. However, the addition of CML macrophages to normal or CML CD14- mesenchymal cells resulted in impaired progenitor support. This finding indicates that the abnormal function of CML bone marrow stroma is related to the presence of malignant macrophages. In contrast to normal LTC-IC, the growth of CML LTC-IC on allogeneic CML stromal layers was not impaired and was significantly better than that of normal LTC-IC cocultured with the same CML stromal layers. These studies demonstrate that, in addition to abnormalities in CML progenitors themselves, abnormalities in the CML marrow microenvironment related to the presence of malignant stromal macrophages may contribute to the selective expansion of leukemic progenitors and suppression of normal hematopoiesis in CML.     

Dynamic path analysis – a useful tool to investigate mediation processes in clinical survival trials

When it comes to clinical survival trials, regulatory restrictions usually require the application of methods that solely utilize baseline covariates and the intention‐to‐treat principle. Thereby, much potentially useful information is lost, as collection of time‐to‐event data often goes hand in hand with collection of information on biomarkers and other internal time‐dependent covariates. However, there are tools to incorporate information from repeated measurements in a useful manner that can help to shed more light on the underlying treatment mechanisms. We consider dynamic path analysis, a model for mediation analysis in the presence of a time‐to‐event outcome and time‐dependent covariates to investigate direct and indirect effects in a study of different lipid‐lowering treatments in patients with previous myocardial infarctions. Further, we address the question whether survival in itself may produce associations between the treatment and the mediator in dynamic path analysis and give an argument that because of linearity of the assumed additive hazard model, this is not the case. We further elaborate on our view that, when studying mediation, we are actually dealing with underlying processes rather than single variables measured only once during the study period. This becomes apparent in results from various models applied to the study of lipid‐lowering treatments as well as our additionally conducted simulation study, where we clearly observe that discarding information on repeated measurements can lead to potentially erroneous conclusions. Copyright © 2015 John Wiley & Sons, Ltd.     

5-Azacytidine. A new anticancer drug with effectiveness in acute myelogenous leukemia.

Clinical studies involving 5-azacytidine, a ring analogue of cytidine, began in Europe in 1967 and the United States in 1970, and we review available preclinical and clinical studies here. The drug possesses cytotoxic, antimicrobial, antineoplastic, abortive, and mutagenic activity in various biological systems. 5-Azacytidine is thought to exert its antineoplastic effect through interference with nucleic acid metabolism. The dose-limiting toxicities are nausea, vomiting, and leukopenia, while the incidence of thrombocytopenia is low. Hepatic toxicity ranges from abnormal findings in liver function tests to hepatic coma. Clinical results in solid tumors are not encouraging, but 5-azacytidine shows consistent antitumor activity in patients with acute myelogenous leukemia resistant to previous treatment. An overall response rate of 36%, with 20% complete remissions, was achieved in 200 previously treated patients with acute myelogenous leukemia. Further studies must define the role of 5-azacytidine alone and in combination for the first-line treatment of acute myelogenous leukemia.     

Model for estimation of clinically achievable plasma concentrations for investigational anticancer drugs in man

A major problem related to in vitro testing of new investigational anticancer compounds is the lack of accurate pharmacokinetic data for the drugs in man. Based on the concept of a relationship between certain toxicologic endpoints in animal systems and maximally tolerated doses in man, we hypothesized that a comparable agreement might exist between these experimental animal toxicology data and clinically achievable peak plasma concentrations (PPCs). A retrospective analysis of the known data pairs of 28 commonly used cytotoxic compounds supports the existence of a reasonably good correlation between ip LD50 values (Pearson test) in nontumored mice and PPCs in man (r2 = 0.501; P less than 0.0001). Our data suggest that by use of the resultant statistical regression model a rational starting point can be selected for in vitro screening of entirely new agents for which human PPCs are not available. Additionally, application of this approach may also prove useful in relation to selecting in vitro doses for chemosensitivity assays intended for predictive correlation with clinical response in cancer patients.     

Quantitative analysis of MDR1 (multidrug resistance) gene expression in human tumors by polymerase chain reaction.

The resistance of tumor cells to chemotherapeutic drugs is a major obstacle to successful cancer chemotherapy. In human cells, expression of the MDR1 gene, encoding a transmembrane efflux pump (P-glycoprotein), leads to decreased intracellular accumulation and resistance to a variety of lipophilic drugs (multidrug resistance; MDR). The levels of MDR in cell lines selected in vitro have been shown to correlate with the steady-state levels of MDR1 mRNA and P-glycoprotein. In cells with a severalfold increase in cellular drug resistance, MDR1 expression levels are close to the limits of detection by conventional assays. MDR1 expression has been frequently observed in human tumors after chemotherapy and in some but not all types of clinically refractory tumors untreated with chemotherapeutic drugs. We have devised a highly sensitive, specific, and quantitative protocol for measuring the levels of MDR1 mRNA in clinical samples, based on the polymerase chain reaction. We have used this assay to measure MDR1 gene expression in MDR cell lines and greater than 300 normal tissues, tumor-derived cell lines, and clinical specimens of untreated tumors of the types in which MDR1 expression was rarely observed by standard assays. Low levels of MDR1 expression were found by polymerase chain reaction in most solid tumors and leukemias tested. The frequency of samples without detectable MDR1 expression varied among different types of tumors; MDR1-negative samples were most common among tumor types known to be relatively responsive to chemotherapy.     

Long-term follow-up in patients treated by stent implantation for post-ablation pulmonary vein stenosis

Purpose

Symptomatic severe pulmonary vein stenosis (PVS) after catheter ablation of atrial fibrillation (AF) is a rare but well-recognized complication. Treatment options include pulmonary vein angioplasty with or without drug eluting balloons or angioplasty with stent implantation. The treatment of choice is unclear. In our center, pulmonary vein stenting is the treatment of choice for significantly stenotic veins. We present the long-term clinical outcome of 9 patients treated with stent implantation.

Methods

Between 2001 and 2015, 3048 patients with AF were treated with catheter ablation at our institution, of which 9 developed symptomatic PVS. A total of 11 PVS were treated. Pre-procedural imaging (CT, MR, transesophageal echocardiography, angiography) was performed in all patients.

Results

Mean time from ablation to stenting was 18 months. Three patients had recurrent pneumonia and the remaining reduced functional capacity (NYHA 2). All patients were in functional capacity NYHA 1 (p?<?0.05) after a mean follow-up of 64 (18–132) months. Three patients still had paroxysmal AF, of which two have undergone repeated ablation.

Conclusions

Symptomatic PVS after AF ablation can be successfully treated by stent implantation with durable results and good clinical outcome. AF ablation is still a feasible option after stent deployment.

     

Apolipoprotein B retention in the grossly normal and atherosclerotic human aorta.

Apoliporotein B (apoB) was measured in buffer-extracted homogenates of grossly normal and artherosclerotic human aortic intima by means of an electroimmunoassay procedure. The apoB values which were expressed as microgram per mg tissue dry weight, varied widely, ranging from 0.34 to 18.45 in normal intima and from 0.8 to 12.5 in fatty fibrous plaques. No consistent differences in apoB content were found between normal intimas from thoracic and abdominal aortic regions. There was a statistically significant positive correlation between the quantity of buffer-extractable apoB in normal regions and the plasma cholesterol and triglyceride concentration. Buffer-extractable apoB values were significantly higher in fatty fibrous plaques than in ulcerated lesions from the same vessel. However, fatty fibrous plaque apoB values were significantly lower than those from grossly normal regions from the same aorta, although the topographical distribution of apoB was more widespread in plaques than in normal regions, as shown by immunofluorescence studies. This apparent discrepancy reflected the incomplete extraction of apoB from plaques as contrasted to normal regions. The relatively loosely bound apoB, extractable by standard buffers, may represent intact low density lipoprotein (LDL) and/or very low density lipoprotein (VLDL), while the tightly bound fraction may represent insoluble complexes of intact lipoproteins within the plaque or delipidated apoB.