Search results for " Drug Resistance"

Recurrences of multidrug-resistant tuberculosis: Strains involved, within-host diversity, and fine-tuned allocation of reinfections

2020

34 páginas, 13 figuras

Evolución de la resistencia transmitida y adquirida a fármacos antirretrovirales en pacientes infectados con VIH-1

2018

Introducción: La adquisición y transmisión de resistencia amenaza el éxito del tratamiento antirretroviral. En este estudio evaluamos el comportamiento epidemiológico de las mutaciones de resistencia (MR) a fármacos antirretrovirales del VIH-1 según factores de riesgo y clínicos específicos. Metodología: Este es un estudio retrospectivo observacional de series transversales acumuladas, realizado en la Unidad de Enfermedades Infecciosas de un hospital universitario en España (CHGUV) entre los años 2003 y 2014. Nuestro objetivo fue estimar la evolución de la frecuencia anual de MR a fármacos antirretrovirales en el genoma de la proteasa y transcriptasa inversa del VIH-1 durante el periodo de …

Extended-Spectrum ß-Lactamase, AmpC-Producing, and Fluoroquinolone-Resistant Escherichia coli in Retail Broiler Chicken Meat, Italy.

2015

Background: Globally, antimicrobial drug-resistant Escherichia coli is among the most common etiological agents of invasive disease in humans. In Europe, increasing proportions of infections due to third-generation cephalosporins and/or fluoroquinolone-resistant extraintestinal pathogenic E. coli (ExPEC) strains are reported. E. coli from poultry are those more closely linked to human E. coli, but lack of reliable data makes it difficult to assess the attributable risk of different food sources. In the present study, our objective was to investigate the antimicrobial resistance profile, phylogenetic background, and virulence factors of E. coli isolates from broiler chicken meat sold at reta…

Effects of Tumor Necrosis Factor-Alpha on Growth and Doxorubicin Sensitivity of Multidrug Resistant Tumor Cell Lines

1993

Biological agents might offer various therapeutic opportunities in the treatment of cancer, including a direct and/or host- mediated antiproliferative effect as well as the possibility to favourably modulate tumor sensitivity to antineoplastic drugs (Alexander et al., 1987; Kikuchi et al., 1992; Wadler and Schwartz, 1990). However, information on their activity on chemoresistant tumors is still scanty (Billi et al., 1991; Bonavida et al., 1989; D’Alessandro, 1993; Fruehauf et al., 1991; Liddill et al., 1988; Mihich and Ehrke, 1991). Here we have focused on tumor necrosis-alpha (TNF-α) and studied its in vitro effects on the growth of two tumor cell lines, the mouse B16 melanoma and Friend e…

Cytotoxicity of compounds from Xylopia aethiopica towards multi-factorial drug-resistant cancer cells.

2015

Abstract Introduction Multidrug resistance (MDR) in cancer represent a major hurdle in chemotherapy. Previously, the methanol extract of the medicinal spice Xylopia aethiopica displayed considerable cytotoxicity against multidrug resistant (MDR) cancer cell lines. Methods The present study was designed to assess the cytotoxicity of compounds, 16 α -hydroxy- ent -kauran-19-oic acid ( 2 ), 3,4′,5-trihydroxy-6″,6″-dimethylpyrano[2,3-g]flavone ( 3 ), isotetrandrine ( 5 ) and trans -tiliroside ( 6 ) derived from the methanol crude extract of Xylopia aethiopica against 9 drug-sensitive and -resistant cancer cell lines. The resazurin reduction assay was used to evaluate the cytotoxicity of these c…

2017

The 6-epimer of the plakortide H acid (1), along with the endoperoxides plakortide E (2), plakortin (3), and dihydroplakortin (4) have been isolated from a sample of the Caribbean sponge Plakortis halichondrioides. To perform a comparative study on the cytotoxicity towards the drug-sensitive leukemia CCRF-CEM cell line and its multi-drug resistant subline CEM/ADR5000, the acid of plakortin, namely plakortic acid (5), as well as the esters plakortide E methyl ester (6) and 6-epi-plakortide H (7) were synthesized by hydrolysis and Steglich esterification, respectively. The data obtained showed that the acids (1, 2, 5) exhibited potent cytotoxicity towards both cell lines, whereas the esters s…

Overcoming of P-glycoprotein-mediated multidrug resistance of tumors in vivo by drug combinations

2014

Summary Inhibition of P-glycoprotein represents an attractive possibility to modulate resistance of cancer cells to anticancer drugs. One major strategy to overcome P-glycoprotein-mediated multidrug resistance (MDR) of tumors is to increase intracellular concentrations of anticancer drugs. This can be achieved by blocking of P-glycoprotein-mediated drug efflux using synthetic or natural small molecules or monoclonal antibodies, which bind to various parts of the efflux channel. Another possibility to increase intracellular drug concentrations can be reached by nanoparticles. A further major strategy to overcome MDR involves the downregulation of P-glycoprotein expression either by therapeut…

Cytotoxicity of fagaramide derivative and canthin-6-one from Zanthoxylum (Rutaceae) species against multidrug resistant leukemia cells

2019

In our continuous search for cytotoxic compounds from the genus Zanthoxylum, chromatographic separation of the MeOH/CH2Cl2 (1:1) extract of Z. chalybeum yielded one new alkamide; 4-(isoprenyloxy)-3-methoxy-3,4-deoxymethylenedioxyfagaramide (1) and a known one; fagaramide (2). Similarly, from the MeOH/CH2Cl2 (1:1) extract of the stem bark of Z. parachanthum four known compounds; canthin-6-one (3), dihydrochelerythrine (4), lupeol (5) and sesamin (6) were isolated. Characterization of the structures of these compounds was achieved using spectroscopic techniques (NMR and MS). Using resazurin reduction assay 1, 3 and 6 displayed moderate cytotoxicity with IC50 values below 50 μM against the dru…

Role of P-Glycoprotein for Resistance of Tumors to Anticancer Drugs: From Bench to Bedside

2014

Success of cancer chemotherapy is limited by simultaneous resistance towards many anticancer drugs making clinical combination therapy protocols less efficient. P-glycoprotein represents an efflux pump of the ABC transporter family, which recognizes and extrudes anticancer drugs of diverse chemical classes and biochemical functions. The P-glycoprotein-mediated profile of cross-resistance has been termed multidrug resistance (MDR). In our investigations, we focused on MDR of in vivo tumor lines maintained in mice. The development of in vivo resistance towards anthracyclines (doxorubicin, daunorubicin) in L1210 and S180 ascites tumor lines was accompanied with decreased uptake and increased e…

Cancer Stem Cells: From Birth to Death

2019

Abstract Conspicuous investigations have proven the role of cancer stem cells (CSCs) in the onset and progression of a plethora of liquid and solid neoplasms. CSCs are endowed with the capability of initiating tumor growth and becoming dormant at distant organ sites just waiting for optimal conditions amenable for metastatic outgrowth. This cancer subpopulation is inherently resistant to anticancer therapeutics, and its targeting could avoid metastatic disease, which is largely incurable, and clinical relapses. CSCs are considered the Achilles heel of cancer. However, many efforts are necessary to identify univocal CSC markers as well as specific CSC biomarkers of therapeutic response. Here…