Targeted therapies in pancreatic cancer: Promises and failures

Pancreatic ductal adenocarcinoma (PDAC) is an incidence rate nearly equal to its mortality rate. The poor prognosis of the disease can be explained by the absence of effective biomarkers for screening and early detection, together with the aggressive behavior and resistance to the currently available chemotherapy. The therapeutic failure can also be attributed to the inter-/intratumor genetic heterogeneity and the abundance of tumor stroma that occupies the majority of the tumor mass. Gemcitabine is used in the treatment of PDAC; however, the response rate is less than 12%. A recent phase III trial revealed that the combination of oxaliplatin, irinotecan, fluorouracil, and leucovorin could be an option for the treatment of metastatic PDAC patients with good performance status, although these approaches can result in high toxicity level. Further investigations are required to develop innovative anticancer agents that either improve gemcitabine activity, within novel combinatorial approaches or acts with a better efficacy than gemcitabine. The aim of the current review is to give an overview of preclinical and clinical studies targeting key dysregulated signaling pathways in PDAC.     

Improved non-viral transfection of glial and adult neural stem cell lines and of primary astrocytes by combining agents with complementary modes of action

BACKGROUND: Rational design of gene vectors for therapeutic applications requires understanding of transfection mechanisms. In this study, multiple transfection assays revealed complementary mechanisms between two commonly used transfection agents. This finding was then exploited to produce improved transfection outcomes. METHODS AND RESULTS: Rat C6 glial cells, adult rat hippocampal progenitor cells and primary astrocytes were transfected using Lipofectamine (LA) or polyethylenimine (PEI), in vitro. Although LA- and PEI-transfected populations expressed the same total level of transgene product, LA transfected considerably more cells than PEI (approximately 20 vs. 14%). A fluorescently labelled plasmid and time-course analysis, involving both flow cytometry and confocal microscopy, were used to explain this apparent discrepancy. Results showed that LA delivered more plasmid DNA to the cytoplasm and achieved transgene expression in more cells than PEI. In contrast, PEI transfected fewer cells but, on average, produced more transgene product per transfected cell. CONCLUSIONS: A comparative transfection model was developed to explain these different characteristics. According to this model, transfection is a multistage process with different transfection agents exerting their primary effect at different stages in this process. This model forecast that it should be possible to prepare a chimeric complex with a transfection efficiency that exceeded that achievable with Lipofectamine or polyethylenimine alone. This prediction was tested and shown to hold for glioma cells, primary astrocytes, and adult neural stems cells.     

Bone medullary arterioles from ovariectomized rats have smaller baseline diameters but normal eNOS expression and NO-mediated dilation

This study was designed to test the hypothesis that endogenous estrogens decrease the expression of endothelial nitric oxide synthase (eNOS) in resistance-size bone arterioles, thereby reducing endothelium-dependent vasodilator function. Sexually mature female rats were ovariectomized to reduce endogenous estrogens. Age-matched female rats served as controls. Seven to ten days after ovariectomy, bone marrow tissue was collected from the femoral canal. Immuno-histochemistry was performed to detect expression of estrogen receptors, alpha and beta and eNOS. eNOS protein content in medullary bone arterioles was compared using Western blot analysis. Endothelial cell function was assessed by quantitating the dilation of isolated, pressurized bone arterioles in response to acetylcholine. The results indicate that the endothelium of bone arterioles from ovariectomized and control rats express ER-alpha, ER-beta and eNOS. eNOS protein content in the two groups of arterioles did not differ. However, the baseline diameter of arterioles from ovariectomized rats (63+/-4 microm) was significantly smaller than the diameter of arterioles from control rats (75+/-3 microm, p<0.05). The two groups of arterioles dilated equally in response to acetylcholine. L-NAME, an inhibitor of eNOS, almost completely abolished the dilator responses to acetylcholine, but not to sodium nitroprusside. L-Arginine restored acetylcholine-induced dilation after L-NAME treatment. Thus, arteriole dilation to acetylcholine appears to be mediated almost exclusively by NO. The smaller diameter of arterioles from ovariectomized rats suggests that endogenous estrogens exert a significant dilator influence on bone arterioles. However, the dilator influence does not appear to be mediated by an increase in eNOS expression or enhanced NO-dependent vasodilation. These results indicate that estrogens do not decrease eNOS expression or diminish NO-mediated dilation of bone medullary arterioles.     

Haplo-insufficiency for different genes differentially reduces pathogenicity and virulence in a fungal phytopathogen

The main determinant of pathogenicity in Ustilago maydis is the b-mating locus, where establishment of heterozygosity is sufficient to cause galls/tumors on maize plants. However, matings between haploids where one partner contains a mutation, in e.g., the smu1 gene, encoding a Ste20-like PAK kinase, often show reduced mating and pathogenicity compared to wild type. Here we show that similarly, diploids lacking one copy of smu1, are reduced in production of aerial hyphae, but do not show significantly-reduced virulence. Haplo-insufficiency was also observed for additional genes. UmPde1 is a cyclic phosphodiesterase involved in cAMP turnover as part of the cAMP-dependent PKA pathway. Hsl7 plays a role in cell length and in the filamentous response to low ammonium in haploid cells. Diploids deleted for one copy of either the pde1 or hsl7 genes had reduced or increased production of aerial hyphae, respectively, and both were severely impaired in virulence compared to wild type diploids. rho1 and pdc1 are two genes essential for cell viability in haploids. These genes also displayed haplo-insufficiency for pathogenesis. rho1/Δrho1 diploid cells were defective in pheromone production and detection, aerial hyphae induction, and were avirulent. In contrast, pdc1/Δpdc1 diploid cells only failed to produce tumors when applied to maize whorls. We predict the haplo-insufficiency of most of these signaling components is due to stoichiometric imbalance of the respective gene products with their interacting partners, thereby impairing virulence-induction mechanism(s). Further investigation of the bases for such haplo-insufficiency as well as of additional genes displaying this phenotype will provide important insights into fundamental aspects of development in this organism as well as inter-nuclear communication and genetic control.     

An optimum algorithm in pathological voice quality assessment using wavelet-packet-based features,linear discriminant analysis and support vector machine

Voice impairments, attention to increased unhealthy social behavior and voice abuse, have been increasing dramatically. Therefore, diagnosis of voice diseases has an important role in the opportune treatment of pathologic voices. This paper presents an extensive study in identification of different voice disorders which their origin is in the vocal folds. Firstly, a qualitative study is applied based on short-time Fourier transform (STFT) and continuous wavelet transform (CWT) in order to investigate their aptitude in the presentation of discriminative features to identify disordered voices from normal ones. Therefore, wavelet packet transform (WPT) for their ability to analyze scrutinizingly a signal at several levels of resolution is chosen as strong speech signal parameterization method. The ability of energy and entropy features, obtained from the coefficients in the output nodes of the optimum wavelet packet tree, is investigated. Linear discriminant analysis (LDA) and principal component analysis (PCA) are evaluated as feature dimension reduction methods in order to optimize recognition algorithm. The performance of each structure is evaluated in terms of the accuracy, sensitivity, specificity, and area under the receiver operating curve (AUC). Eventually, entropy features in the sixth level of WPT decomposition along with feature dimension reduction by LDA and a support vector machine-based classification method is the most optimum algorithm that leads to the recognition rate of 100% and AUC of 100%. Proposed system clearly outperforms previous works in both respect of accuracy and reduction of residues; which may lead in full accuracy and high speed diagnosis procedure.     

Contamination level and human health hazard assessment of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in street dust deposited in Mahshahr,southwest of Iran

Mahshahr has a strategic position and is considered as industrial hub of Iran. Selected heavy metals and polycyclic aromatic hydrocarbons (PAHs) contamination and health risk, and the mineralogical composition of street dust from Mahshahr were investigated. Results indicated that geology is the main determinant of the dust mineralogical composition. Calculated enrichment factor (EF) and principal component analysis (PCA) showed that Pb, Hg, Zn, and Cu accumulations are greatly influenced by anthropogenic sources including traffic and industry. High heavy metals content poses great ecological risk in the study area and exposure doses revealed that ingestion is the main exposure route to street dust, especially for children in residential/commercial areas. It was found that the total amount of PAHs (∑PAHs) varies from 161 to 1996 µg/kg, dominated by four-ring PAHs. Diagnostic ratios and PCA showed that both petrogenic and pyrogenic sources of PAHs in Mahshahr street dust and traffic play important roles in this respect. Furthermore, toxic equivalents and incremental lifetime cancer risk of PAHs in street dust indicated a high potential carcinogenic risk for inhabitants mainly via dermal contact and ingestion pathways particularly for outdoor workers in industrial use scenario. Finally, distribution maps of total hazard index of heavy metals and cancer risk of PAHs indicated the most impacted zones for different groups and use scenarios.     

Comparison of the effects of poultry manure and its biochar on barley growth in petroleum-contaminated soils

This study was conducted to evaluate and compare the effectiveness of two organic amendments [poultry manure (PM) and poultry manure biochar (PMB)] for the degradation of petroleum hydrocarbons in contaminated soils by barley plant at three levels of total petroleum hydrocarbons (TPHs) during 5 months under greenhouse conditions. TPHs removal efficiency and microbial respiration were shown to be higher at soil-cultivated plant than at uncultivated soil and in lowest level of contamination rather than other levels of contamination and at organic amendment treatment than unamended soil. Soil microbial respiration and TPHs degradation in the rhizosphere of barley increased by 15.64 and 12.74% for PM-amended treatment and 28.07 and 26.83% for PMB-amended treatment, respectively, in the 4% TPHs level compared with unamended treatment. Comparison of two amendments showed that in PMB treatment soil, highest dry weight, microbial respiration, and TPHs degradation potential were observed.     

Internal virus polarization model for virus retention by the Ultipor® VF Grade DV20 membrane

Several recent studies have reported a decline in virus retention during virus challenge filtration experiments, although the mechanism(s) governing this phenomenon for different filters remains uncertain. Experiments were performed to evaluate the retention of PP7 and PR772 bacteriophage through Ultipor VF Grade DV20 virus filters during constant pressure filtration. While the larger PR772 phage was fully retained under all conditions, a 2‐log decline in retention of the small PP7 phage was observed at high throughputs, even under conditions where there was no decline in filtrate flux. In addition, prefouling the membrane with an immunoglobulin G solution had no effect on phage retention. An internal polarization model was developed to describe the decline in phage retention arising from the accumulation of phage in the upper (reservoir) layer within the filter which increases the challenge to the lower (rejection) layer. Independent support for this internal polarization phenomenon was provided by confocal microscopy of fluorescently labeled phage within the membrane. The model was in good agreement with phage retention data over a wide range of phage titers, confirming that virus retention is throughput dependent and supporting current recommendations for virus retention validation studies. These results provide important insights into the factors governing virus retention by membrane filters and their dependence on the underlying structure of the virus filter membrane. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:856–863, 2014