Stability of a chitosan layer deposited onto a polyethylene surface

A two‐step procedure was applied to obtain antimicrobial films; this procedure involved a corona treatment of the polyethylene (PE) surface and its chemical activation with 1‐ethyl‐3‐[3‐dimethylaminopropyl] carbodiimide hydrochloride and N‐hydroxysuccinimide, and this led to the covalent bonding of chitosan on the PE surface. Electrochemical methods were used to investigate the stability of the deposited chitosan layer. The potentiometric and polyelectrolyte titrations showed that some amount of chitosan desorbed faster from the surface until equilibrium was reached and also that the grafted chitosan layer was more stable than the physically adsorbed one. The chitosan immobilized on the PE surface exhibited the expected antibacterial activity when tested against three bacteria, which included two Gram‐negative bacteria, Salmonella enteritidis and Escherichia coli, and one Gram‐positive bacterium, Listeria monocytogenes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2444–2457, 2013     

TG/FTIR/MS study on the influence of nanoparticles content upon the thermal decomposition of starch/poly(vinyl alcohol) montmorillonite nanocomposites

The effect of the nanoclay content on the thermal decomposition of nanocomposites based on poly(vinyl alcohol)/thermoplastic starch, as intercalated hybrids, has been established. The changes in the decomposition products distribution and their evolution have been investigated by coupled thermogravimetric analysis, Fourier transform infrared spectroscopy, and mass spectrometry. Detailed analysis of the in situ vapor phase showed that the poly(vinyl alcohol)/starch/clay nanocomposites display a completely different distribution pattern of degradation product, depending on nanoclay content. By in situ vapor phase FTIR and MS spectroscopic techniques, both decomposition compounds of the constituent polymers and some new ones, depending on the nanoparticles content, are identified. The effect of the increase in nanoparticles content consists mainly in variation of some volatile compounds evolution, such as formic acid, water, formaldehyde, propionic acid, methanol, acetic acid carbon dioxide, benzene, etc., which in the case of nanocomposites is very complex. Thus, a content of 2–4 wt% organically-modified montmorillonite hinders the decomposition of the poly(vinyl alcohol)/starch blend. Both characteristic temperature of evolution of the main compounds increases by increasing its content and evolution starting time is delayed; while the untreated nanoclay acts like a catalyst, which decreases characteristic temperatures and evolution time with increasing its content. The temperature dependence of the maximum evolution rate of various compounds on the nanoclay content is very complex as, in the case of nanocomposites, of both primary and secondary reactions and transport phenomena occur simultaneously. Generally, this behavior is related to the dispersion of nanoclays in the polymeric matrix.     

Effect of the surface modification of the synthetic meshes used in the surgical treatment of pelvic organ prolapse on the tissue adhesion and clinical functionality

Stress urinary incontinence and pelvic organ prolapse represent important conditions affecting adult women’s health. Lately, the properties and performance of the polymer materials used in the treatment of pelvic organ prolapse have been improved by modulating from their formula. Materials investigated in our study are polypropylene meshes used by clinicians in surgical treatment of urinary incontinence and utero-vaginal prolapse. In order to make a comparative analysis, we confronted the structure and surface morphology of native synthetic polypropylene meshes with explanted fragments from the same mesh type after clinical use. FTIR investigations revealed little change in structure after implantation, somehow insignificant. Scanning electron microscopy (SEM) demonstrates modification in surface morphology even just by passing through the transobturator passage, whereas after implantation the surface deteriorates. SEM on explanted meshes proves the encapsulation process of the mesh to be more similar to a foreign body reaction rather than to the adhesion and integration of the synthetic mesh into the organism. Histological analysis of the surrounding tissues near explanted mesh was made in some relevant clinical cases, because the tissue response is an important factor in order to evaluate the tissue adhesion at the polypropylene mesh surface. Based on our experiments and clinical experience we’ve designed an adhesion score. It applies to meshes used in pelvic organ prolapse surgery measuring the following important factors: tenacity, extent of adhesion, macroscopic and microscopic aspects and ease of dissection from surrounding tissues.     

Development of a stability intelligent control system for turning

This paper presents a stability control system based on a new strategy, with application in turning. It works by permanent assessment of the system operating point position relative to the stability limit, and process parameter permanent, in-process modification such as this point is always placed in the stable domain zone that gives the highest process performance. In the case of turning, here approached: (1) this zone is the stability limit proximity; (2) the system operating point position is determined by assessing a cutting force monitored signal feature; and (3) this position is changed by modifying the cutting edge setting angle, the feed rate, and the cutting speed, as it follows: when the risk of overpassing the stability limit is imminent, the setting angle is increased, followed by a feed rate diminishing and then by a worked piece rotation speed reduction, while immediately after surpassing the risk, the three variables modification is reversed, this way the chatter onset being permanently avoided and the performance kept in every moment at the highest possible level. The system was experimentally implemented on a transversal lathe. The results of tests on dedicatedly designed specimens are showing a machining productivity significant increase, in conditions of a stable cutting process. The system is simple, and it can be easily added to the existing CNC machine tools, without important modifications.     

Application of Optimal Homotopy Asymptotic Method for solving nonlinear equations arising in heat transfer

We consider one of the newest analytical methods, the Optimal Homotopy Asymptotic Method (OHAM), to solve nonlinear equations arising in heat transfer. Two specific applications are considered: cooling of a lumped system with variable specific heat and the temperature distribution equation in a thick rectangular fin radiation to free space. Results obtained by OHAM, which does not need small parameters are compared with numerical results and a very good agreement was found. This method provides us with a convenient way to control the convergence of approximation series and adjust convergence regions when necessary. The results reveal that the proposed method is explicit, effective and easy to use.     

Leptin Signaling in Obesity and Colorectal Cancer

Obesity and colorectal cancer (CRC) are among the leading diseases causing deaths in the world, showing a complex multifactorial pathology. Obesity is considered a risk factor in CRC development through inflammation, metabolic, and signaling processes. Leptin is one of the most important adipokines related to obesity and an important proinflammatory marker, mainly expressed in adipose tissue, with many genetic variation profiles, many related influencing factors, and various functions that have been ascribed but not yet fully understood and elucidated, the most important ones being related to energy metabolism, as well as endocrine and immune systems. Aberrant signaling and genetic variations of leptin are correlated with obesity and CRC, with the genetic causality showing both inherited and acquired events, in addition to lifestyle and environmental risk factors; these might also be related to specific pathogenic pathways at different time points. Moreover, mutation gain is a crucial factor enabling the genetic process of CRC. Currently, the inconsistent and insufficient data related to leptin’s relationship with obesity and CRC indicate the necessity of further related studies. This review summarizes the current knowledge on leptin genetics and its potential relationship with the main pathogenic pathways of obesity and CRC, in an attempt to understand the molecular mechanisms of these associations, in the context of inconsistent and contradictory data. The understanding of these mechanisms linking obesity and CRC could help to develop novel therapeutic targets and prevention strategies, resulting in a better prognosis and management of these diseases.     

Glioblastoma Stem Cells—Useful Tools in the Battle against Cancer

Glioblastoma stem cells (GSCs) are cells with a self-renewal ability and capacity to initiate tumors upon serial transplantation that have been linked to tumor cell heterogeneity. Most standard treatments fail to completely eradicate GSCs, causing the recurrence of the disease. GSCs could represent one reason for the low efficacy of cancer therapy and for the short relapse time. Nonetheless, experimental data suggest that the presence of therapy-resistant GSCs could explain tumor recurrence. Therefore, to effectively target GSCs, a comprehensive understanding of their biology and the survival and developing mechanisms during treatment is mandatory. This review provides an overview of the molecular features, microenvironment, detection, and targeting strategies of GSCs, an essential information required for an efficient therapy. Despite the outstanding results in oncology, researchers are still developing novel strategies, of which one could be targeting the GSCs present in the hypoxic regions and invasive edge of the glioblastoma.     

Comparative Antimicrobial Activity of Silver Nanoparticles Obtained by Wet Chemical Reduction and Solvothermal Methods

The synthesis of nanoparticles from noble metals has received high attention from researchers due to their unique properties and their wide range of applications. Silver nanoparticles (AgNPs), in particular, show a remarkable inhibitory effect against microorganisms and viruses. Various methods have been developed to obtain AgNPs, however the stability of such nanostructures over time is still challenging. Researchers attempt to obtain particular shapes and sizes in order to tailor AgNPs properties for specific areas, such as biochemistry, biology, agriculture, electronics, medicine, and industry. The aim of this study was to design AgNPs with improved antimicrobial characteristics and stability. Two different wet chemical routes were considered: synthesis being performed (i) reduction method at room temperatures and (ii) solvothermal method at high temperature. Here, we show that the antimicrobial properties of the obtained AgNPs, are influenced by their synthesis route, which impact on the size and shape of the structures. This work analyses and compares the antimicrobial properties of the obtained AgNPs, based on their structure, sizes and morphologies which are influenced, in turn, not only by the type or quantities of precursors used but also by the temperature of the reaction. Generally, AgNPs obtained by solvothermal, at raised temperature, registered better antimicrobial activity as compared to NPs obtained by reduction method at room temperature.     

Cardiac Toxicity Associated with Immune Checkpoint Inhibitors: A Systematic Review

Immune checkpoint inhibitors (ICIs) are an important advancement in the field of cancer treatment, significantly improving the survival of patients with a series of advanced malignancies, like melanoma, non-small cell lung cancer (NSCLC), hepatocellular carcinoma (HCC), renal cell carcinoma (RCC), and Hodgkin lymphoma. ICIs act upon T lymphocytes and antigen-presenting cells, targeting programmed cell death protein 1 (PD1), programmed cell death protein ligand 1 (PD-L1), and cytotoxic T-lymphocyte antigen 4 (CTLA-4), breaking the immune tolerance of the T cells against malignant cells and enhancing the body’s own immune response. A variety of cardiac-adverse effects are associated with ICI-based treatment, including pericarditis, arrhythmias, cardiomyopathy, and acute coronary syndrome, with myocarditis being the most studied due to its often-unexpected onset and severity. Overall, Myocarditis is rare but presents an immune-related adverse event (irAE) that has a high fatality rate. Considering the rising number of oncological patients treated with ICIs and the severity of their potential adverse effects, a good understanding and continuous investigation of cardiac irAEs is of the utmost importance. This systematic review aimed to revise recent publications (between 2016–2022) on ICI-induced cardiac toxicities and highlight the therapeutical approach and evolution in the selected cases.     

Bioavailability Improvement Strategies for Icariin and Its Derivates: A Review

In recent years, there has been considerable interest in icariin (ICA) and its derivates, icariside II (ICS) and icaritin (ICT), due to their wide range of potential applications in preventing cancer, cardiovascular disease, osteoporosis, delaying the effects of Alzheimer’s disease, treating erectile dysfunction, etc. However, their poor water solubility and membrane permeability, resulting in low bioavailability, dampens their potential beneficial effects. In this regard, several strategies have been developed, such as pharmaceutical technologies, structural transformations, and absorption enhancers. All these strategies manage to improve the bioavailability of the above-mentioned flavonoids, thus increasing their concentration in the desired places. This paper focuses on gathering the latest knowledge on strategies to improve bioavailability for enhancing the efficacy of icariin, icariside II, and icaritin. We conclude that there is an opportunity for many further improvements in this field. To the best of our knowledge, no such review articles scoping the bioavailability improvement of icariin and its derivates have been published to date. Therefore, this paper can be a good starting point for all those who want to deepen their understanding of the field.