Biodegradable polymer nanocomposites of poly(lactic acid) (PLA) and several organically modified montmorillonites (nanoclays), namely, Cloisite 30B, Cloisite Na + , Cloisite 25A, Cloisite 20A, Cloisite 93A, and Cloisite 15A were prepared by melt compounding using a Brabender twin-screw extruder. An exfoliated morphology was observed using both X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM) for the combination of PLA and Cloisite 30B (the montmorillonite modified with a quaternary ammonium salt). The first XRD peaks for all the other nanocomposites were observed to shift to lower angles, indicating that intercalation occurred. The extent of intercalation depended on the type of organic modification on the Cloisite organoclay and was exhibited in the sequence of Cloisite Na + > 25A > 20A > 93A > 15A. Further studies were carried out to compare the properties of the PLA-30B nanocomposites with those of the neat PLA at clay loading levels of 1%, 2%, 3%, 4%, and 5% (w/w). Thermal stability of the nanocomposites was studied using thermogravimetric analysis (TGA). An increase in thermal stability was observed with a high at a loading level of 3% (w/w).
Biodegradable Poly(Lactic Acid)/Clay Nanocomposites 337Glass transition data were collected and analyzed using differential scanning calorimeter (DSC). An optimum in the glass transition temperature T g of the nanocomposites was observed at 3% (w/w). Improvement in the mechanical properties of the nanocomposites was also observed.
Abstract. It was originally thought that no single routine blood test result would be able to indicate whether or not a patient had cancer; however, several novel studies have indicated that the median survival and prognosis of cancer patients were markedly associated with the systemic circulation features of cancer patients. In addition, certain parameters, such as white blood cell (WBC) count, were largely altered in malignant tumors. In the present study, routine blood tests were performed in order to observe the change of blood cells in tumor-bearing mice following the implantation of 4T1 breast cancer cells into the mammary fat pad; in addition, blood flow in breast tumor sites was measured indirectly using laser Doppler perfusion imaging (LDPI), in an attempt to explain the relevance between the blood circulation features and the growth or metastasis of breast cancer in mice model. The LDPI and blood test results indicated that the implantation of 4T1 breast cancer cells into BALB/c mice led to thrombosis as well as high WBC count, high platelet count, high plateletcrit and low blood perfusion. Following implantation of the 4T1 cells for four weeks, the lung metastatic number was determined and the Pearson correlation coefficient revealed that the number of visceral lung metastatic sites had a marked negative association with the ratio of basophils (BASO%; r=-0.512; P<0.01) and the mean corpuscular hemoglobin was significantly correlated with primary tumor weight (r=0.425; P<0.05). In conclusion, the results of the present study demonstrated that tumor growth led to thrombosis and acute anemia in mice; in addition, when blood BASO% was low, an increased number of lung metastases were observed in tumor-bearing mice.
IntroductionOver the past several decades, developments in clinical and surgical treatments for cancer patients has led to increased overall survival rates (1). However, the growth of primary tumors and subsequent cancer metastases continue to cause mortality and prevent effective treatment (2). Vascular dissemination is a major mechanism by which breast cancer cells migrate into the systemic circulation, leading to distant metastasis and mortality (3). Clinical observations have indicated a potential association between the bloodstream and cancer metastasis (4-5). However, few studies have investigated the systemic circulation characterization in mouse breast cancer metastasis models, which therefore limits the development of experimental oncology research.Cancer patients have frequently been reported to present with symptoms of thrombosis, which are more severe if the disease has progressed to a metastatic stage (6,7). In order for metastases to form, cancer cells must be able to survive in the harsh circulatory environment and extravasate into distant sites. Thrombosis may improve the anchoring of 'seed' (tumor cells that have escaped surgical removal or that may have already disseminated) to 'soil' (target organ) (8). Therefore,
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