Polymers tailored for controlled (bio)degradation through end-group and in-chain functionalization

Currently, polymers can be created with specific properties that are tailored to a wide range of applications from medical to everyday products as packaging. There are different techniques to prepare novel polymer materials with various architectures and specific groups via a variety of reaction mechanisms of different complexity. End-group modification of polymers is a powerful tool for tailoring polymer properties. The end-group and in-chain functionalization strategy must be carefully selected based on catalyst, polymerization conditions, and other limitations such as solute solvent interactions or aggregation. The review provides a brief description of the functional moieties and an outline of synthetic strategies used for tailoring the (bio)degradable polymer properties by end-group and in-chain functionalization.Centre of Polymer and Carbon Materials, Polish Academy of Sciences, University of Wolverhampto

Evaluation of distant results after lamivudine discontinuation in children with chronic hepatitis B.

The aim of this study was to estimate distant results after discontinuation of long term lamivudine treatment in children with chronic hepatitis B. Furthermore, the emergence of HBV polymerase gene variants in YMDD motif during therapy was examined. Additionally, the most commonly occurring type of mutation in the polymerase YMDD region were investigated. The study involved 27 HBeAg positive children with chronic hepatitis B. Children included to lamivudine therapy were previously treated without effects with interferon alpha

Increased MET Gene Copy Number but Not mRNA Level Predicts Postoperative Recurrence in Patients with Non–Small Cell Lung Cancer

AbstractThe aim of the present study was to investigate the relationship of MET copy number (CN) and MET mRNA expression to other molecular alterations, clinicopathologic characteristics, and survival of patients with resected non–small cell lung cancer. One hundred fifty-one paired surgical samples of tumor and tumor-distant normal lung tissues were analyzed by comparative quantitative polymerase chain reaction (PCR) methods with commercially available assays and the CopyCaller software v. 1.0 for post-PCR data processing (downloadable from www.appliedbiosystems.com). MET copy gain (set as more than 3.0 copies per cell) was found in 18.5% of the samples and occurred more frequently in the adenocarcinomas (ADCs) with an increased epidermal growth factor receptor (EGFR) or human epidermal growth factor receptor 2 (HER2) CN (P = .001 and .030 for EGFR and HER2, respectively) and in the ADCs with EGFR activating mutations (P = .051) but did not correlate with KRAS dosage or mutational status. MET mRNA level was 1.76-fold higher [95% confidence interval (CI), 1.29-2.40] in the tumor compared to unaffected lung tissue and associated significantly with MET CN (beta coefficient, 1.51; 95% CI, 1.22-1.87; P < .001). In the multivariable analysis, patients diagnosed with ADC with increased MET CN had a significantly higher risk of disease recurrence (hazard ratio, 1.76; 95% CI, 1.20-2.57; P = .004). An increased MET CN in combination with histologic type appears to be a prognostic factor in patients with ADC after a curative surgery

Predicted Studies of Branched and Cross-Linked Polyurethanes Based on Polyhydroxybutyrate with Polycaprolactone Triol in Soft Segments

The number of cross-links in the non-linear polyurethane structure is the basic factor affecting its properties. Selected properties of aliphatic polyurethanes with soft segments made of different amounts of polycaprolactonetriol, polycaprolactonediol and synthetic, telechelic poly([R,S]-3-hydroxybutyrate) were determined. On the basis of changes in polyurethane properties, the correlation between these properties and the construction of soft segments was found. The structure of polyurethanes, their morphology, hydrophilicity, thermal and mechanical properties were examined. These properties were changed linearly up to 15% content of polycaprolactonetriol in soft segments. A further increase in the amount of triol causes that these properties are mainly determined by the high number of cross-links.This research was founded by the National Science Center Miniatura 2 project no. 2018/02/X/ST5/02005 and partially by the UMG research project no. WPiT/2020/PZ/01

Forensic engineering of advanced polymeric materials Part IV: Case study of oxo-biodegradable polyethylene commercial bag – Aging in biotic and abiotic environment

This is an accepted manuscript of an article published by Elsevier in Waste Management on 03/04/2017, available online: https://doi.org/10.1016/j.wasman.2017.03.043 The accepted version of the publication may differ from the final published version.The public awareness of the quality of environment stimulates the endeavor to safe polymeric materials and their degradation products. The aim of the forensic engineering case study presented in this paper is to evaluate the aging process of commercial oxo-degradable polyethylene bag under real industrial composting conditions and in distilled water at 70 °C, for comparison. Partial degradation of the investigated material was monitored by changes in molecular weight, thermal properties and Keto Carbonyl Bond Index and Vinyl Bond Index, which were calculated from the FTIR spectra. The results indicate that such an oxo-degradable product offered in markets degrades slowly under industrial composting conditions. Even fragmentation is slow, and it is dubious that biological mineralization of this material would occur within a year under industrial composting conditions. The slow degradation and fragmentation is most likely due to partially crosslinking after long time of degradation, which results in the limitation of low molecular weight residues for assimilation. The work suggests that these materials should not be labeled as biodegradable, and should be further analyzed in order to avoid the spread of persistent artificial materials in nature

Degradability of Polyurethanes and Their Blends with Polylactide, Chitosan and Starch

One of the methods of making traditional polymers more environmentally friendly is to modify them with natural materials or their biodegradable, synthetic equivalents. It was assumed that blends with polylactide (PLA), polysaccharides: chitosan (Ch) and starch (St) of branched polyurethane (PUR) based on synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) would degrade faster in the processes of hydrolysis and oxidation than pure PUR. For the sake of simplicity in the publication, all three modifiers: commercial PLA, Ch created by chemical modification of chitin and St are called bioadditives. The samples were incubated in a hydrolytic and oxidizing environment for 36 weeks and 11 weeks, respectively. The degradation process was assessed by observation of the chemical structure as well as the change in the mass of the samples, their molecular weight, surface morphology and thermal properties. It was found that the PUR samples with the highest amount of R,S-PHB and the lowest amount of polycaprolactone triol (PCLtriol) were degraded the most. Moreover, blending with St had the greatest impact on the susceptibility to degradation of PUR. However, the rate of weight loss of the samples was low, and after 36 weeks of incubation in the hydrolytic solution, it did not exceed 7% by weight. The weight loss of Ch and PLA blends was even smaller. However, a significant reduction in molecular weight, changes in morphology and changes in thermal properties indicated that the degradation of the samples should occur quickly after this time. Therefore, when using these polyurethanes and their blends, it should be taken into account that they should decompose slowly in their initial life. In summary, this process can be modified by changing the amount of R,S-PHB, the degree of cross-linking, and the type and amount of second blend component added (bioadditives).This research was founded by the National Science Center Poland Miniatura 2 project no. 2018/02/X/ST5/02005 and partially by the UMG research project no. WZNJ/2021/PZ/02

Ketoacidosis and otitis media as a potencial cause of cerebral venous thrombosis in a 7-year-old boy

Cerebral venous sinus thrombosis (CVST) in childhood is a rare disorder, occurring most often in the neonatal period, with mortality approaching 10%. This condition has multifactorial etiology including common childhood illnesses such as fever, infection, dehydration, and anemia, as well as acute and chronic medical conditions such as congenital heart disease, nephrotic syndrome,&nbsp; and malignancy. Thrombosis can also develop and propagate in response to local venous stasis. A large number of children have coincident local head or neck pathology, including head trauma, brain tumors, or recent intracranial surgery. Clinical symptoms are frequently nonspecific and include seizures, depressed level of consciousness, coma, lethargy, nausea, vomiting, headache, visual impairment, papilledema, and hemiparesis, which may often obscure the diagnosis and delay treatment. In the case of patients with neurological symptoms, imaging studies such as computed tomography (CT)&nbsp; and magnetic resonance imaging (MRI) are invaluable in diagnostics of various pathologies of the nervous system, because of their non-invasiveness, high sensitivity, and specificity. Early diagnosis with management along with a plan for secondary prevention can save from catastrophic consequences