Obesity is on the rise worldwide, and consequently, obesity-related non-communicable diseases are as well. Nutritional overload induces metabolic adaptations in an attempt to restore the disturbed balance, and the byproducts of the mechanisms at hand include an increased generation of reactive species. Obesity-related oxidative stress causes damage to vulnerable systems and ultimately contributes to neoplastic transformation. Dysfunctional obese adipose tissue releases cytokines and induces changes in the cell microenvironment, promoting cell survival and progression of the transformed cancer cells. Other than the increased risk of cancer development, obese cancer patients experience higher mortality rates and reduced therapy efficiency as well. The fact that obesity is considered the second leading preventable cause of cancer prioritizes the research on the mechanisms connecting obesity to cancerogenesis and finding the solutions to break the link. Oxidative stress is integral at different stages of cancer development and advancement in obese patients. Hypocaloric, balanced nutrition, and structured physical activity are some tools for relieving this burden. However, the sensitivity of simultaneously treating cancer and obesity poses a challenge. Further research on the obesity–cancer liaison would offer new perspectives on prevention programs and treatment development.
8 May 2012 in Journal of Biomaterials Science, Polymer Edition
Novel polyurethane co-polymers (TPUs), based on poly(ϵ-caprolactone)-block-poly(dimethylsiloxane)-block-poly(ϵ-caprolactone) (PCL-PDMS-PCL) as soft segment and 4,4'-methylenediphenyl diisocyanate (MDI) and 1,4-butanediol (BD) as hard segment, were synthesized and evaluated for biomedical applications. The content of hard segments (HS) in the polymer chains was varied from 9 to 63 wt%. The influence of the content and length of the HS on the thermal, surface, mechanical properties and biocompatibility was investigated. The structure, composition and HS length were examined using (1)H- and quantitative (13)C-NMR spectroscopy. DSC results implied that the synthesized TPUs were semicrystalline polymers in which both the hard MDI/BD and soft PCL-PDMS-PCL segments participated. It was found that an increase in the average HS length (from 1.2 to 14.4 MDI/BD units) was accompanied by an increase in the crystallinity of the hard segments, storage moduli, hydrophilicity and degree of microphase separation of the co-polymers. Depending on the HS content, a gradual variation in surface properties of co-polymers was revealed by FT-IR, AFM and static water contact angle measurements. The in vitro biocompatibility of co-polymers was evaluated using the endothelial EA.hy926 cell line and protein adsorption on the polyurethane films. All synthesized TPUs adsorbed more albumin than fibrinogen from multicomponent protein mixture, which may indicate biocompatibility. The polyurethane films with high HS content and/or high roughness coefficient exhibit good surface properties and biocompatible behavior, which was confirmed by non-toxic effects to cells and good cell adhesion. Therefore, the non-cytotoxic chemistry of the co-polymers makes them good candidates for further development as biomedical implants.
Summary: Real-time RT PCR has been recognized as an accurate, reliable and sensitive method for quantifying gene transcription. However, several steps preceding PCR represent critical points and source of inaccuracies. These steps include cell processing, RNA extraction, RNA storage, assessment of RNA concentration and cDNA synthesis. To compensate for potential variability introduced by the procedure, normalization of target gene expression has been established. Accurate normalization has become an absolute prerequisite for the correct quantification of gene expression. Several strategies are in use for the normalization of data, including normalization to sample size, to total RNA or to an internal reference. Among these, the use of housekeeping genes as an internal (endogenous) control is the most common approach. Given the increased sensitivity, reproducibility and large dynamic range of this methodology, the requirements for a proper reference gene for normalization have become increasingly stringent. The aim of this paper is to discuss the concept of normalization in mRNA quantification, as well as to discuss several statistical algorithms developed to help the validation of potential reference genes. By showing that the use of inappropriate endogenous control might lead to incorrect results and misinterpretation of experimental data, we are joining the creators of Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) in an attempt to convince scientists that proper validation of potential reference genes is an absolute prerequisite for correct normalization and, therefore, for providing accurate and reliable data by quantitative real-time RT PCR gene expression analyses.