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Hydrated State (hydrated + state)
Selected AbstractsX-ray fluorescence microprobe imaging in biology and medicineJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2006Tatjana Paunesku Abstract Characteristic X-ray fluorescence is a technique that can be used to establish elemental concentrations for a large number of different chemical elements simultaneously in different locations in cell and tissue samples. Exposing the samples to an X-ray beam is the basis of X-ray fluorescence microscopy (XFM). This technique provides the excellent trace element sensitivity; and, due to the large penetration depth of hard X-rays, an opportunity to image whole cells and quantify elements on a per cell basis. Moreover, because specimens prepared for XFM do not require sectioning, they can be investigated close to their natural, hydrated state with cryogenic approaches. Until several years ago, XFM was not widely available to bio-medical communities, and rarely offered resolution better then several microns. This has changed drastically with the development of third-generation synchrotrons. Recent examples of elemental imaging of cells and tissues show the maturation of XFM imaging technique into an elegant and informative way to gain insight into cellular processes. Future developments of XFM,building of new XFM facilities with higher resolution, higher sensitivity or higher throughput will further advance studies of native elemental makeup of cells and provide the biological community including the budding area of bionanotechnology with a tool perfectly suited to monitor the distribution of metals including nanovectors and measure the results of interactions between the nanovectors and living cells and tissues. J. Cell. Biochem. 99: 1489,1502, 2006. © 2006 Wiley-Liss, Inc. [source] Release mechanisms from gentamicin loaded poly(lactic- co -glycolic acid) (PLGA) microparticlesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2002Wolfgang Friess Abstract To provide local gentamicin delivery for 1 week based on a biodegradable system, poly(lactic- co -glycolic acid) (PLGA) microparticles were developed utilizing a 50/50 blend of Resomer® RG 502H, an uncapped variety of 13.5 kD, and Resomer® RG 503, an endcapped polymer of 36.2 kD. The liberation mechanism was investigated by analysis of morphological changes and thermal analysis focusing on the polymer glass transition temperature (Tg) and the mechanical properties. The release of gentamicin was related to a structural breakdown of the particles reaching a critical molecular weight. A Tg of <,37°C in the hydrated state was not indicative of collapse and agglomeration of the particles because the mechanical strength of the polymer structures in the rubbery state may still render sufficient support. As the gap between incubation temperature and Tg widened, the mechanical stability of the PLGA microparticles decreased and became decisive. Particles prepared with RG 502H show a lower ability to bear mechanical stress than RG 503 and 50/50 RG 502H/RG 503 microparticles. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91: 845,855, 2002 [source] Anhydrobiosis in tardigrades and its effects on longevity traitsJOURNAL OF ZOOLOGY, Issue 3 2008S. Hengherr Abstract Living in harsh and variable environments that are prone to periodic desiccation, tardigrades exhibit remarkable tolerance against physical extremes through a state known as anhydrobiosis. To study the effect of this state on the longevity and hence the lifecycle in the taxon Tardigrada for the first time, we exposed a tardigrade species, Milnesium tardigradum, to alternating periods of drying and active feeding periods in a hydrated state. Compared with a hydrated control, the periodically dried animals showed a similar longevity, indicating that the time spent in anhydrobiosis was ignored by the internal clock. Thus, desiccation can produce a time shift in the age of tardigrades similar to the model described for rotifers that has been termed ,Sleeping Beauty'. [source] Methods for additive hydration allowing observation of fully hydrated state of wet samples in environmental SEMMICROSCOPY RESEARCH AND TECHNIQUE, Issue 2 2007Vilém Ned Abstract Methods for additive hydration are presented that enable longtime observation of very wet biological specimens in an environmental scanning electron microscope. The changes of structure due to dehydration for specimens placed on a Peltier-cooled holder, put on a special agar base or embedded in it or blown over by water vapor are compared. The degree of dehydration damage of the observed specimen structures is evaluated and compared with the structure of a nondestructively dried specimen, prepared by the critical point drying method. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc. [source] Preparation and mechanical properties of poly(chitosan- g - DL -lactic acid) fibrous mesh scaffoldsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2 2008Ying Wan Abstract DL -lactic acid was grafted onto chitosan to produce poly(chitosan- g - DL -lactic acid)(PCLA) without using a catalyst. These PCLAs were then spun into filaments and further fabricated into fibrous mesh scaffolds using an improved wet-spinning technique. The diameter of filaments in different scaffolds could vary from a few micrometers to several tens of micrometers. The scaffolds exhibited various pore sizes ranging from about 20,µm to more than 200,µm and different porosities up to 80%. The several main processing conditions were optimized for obtaining the desired scaffolds with well-controlled structures. The tensile and compressive mechanical properties of the mesh scaffolds in both dry and hydrated states were mainly examined. Significantly improved tensile strength and modulus, enhanced compressive modulus, and stress as well as the dimensional stability for these mesh scaffolds in their hydrated state were observed. Copyright © 2007 John Wiley & Sons, Ltd. [source] A biomimetic tubular scaffold with spatially designed nanofibers of protein/PDS® bio-blends,BIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009Vinoy Thomas Abstract Electrospun tubular conduit (4,mm inner diameter) based on blends of polydioxanone (PDS II®) and proteins such as gelatin and elastin having a spatially designed trilayer structure was prepared for arterial scaffolds. SEM analysis of scaffolds showed random nanofibrous morphology and well-interconnected pore network. Due to protein blending, the fiber diameter was reduced from 800,950,nm range to 300,500,nm range. Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) results confirmed the blended composition and crystallinity of fibers. Pure PDS scaffold under hydrated state exhibited a tensile strength of 5.61,±,0.42,MPa and a modulus of 17.11,±,1.13,MPa with a failure strain of 216.7,±,13%. The blending of PDS with elastin and gelatin has decreased the tensile properties. A trilayer tubular scaffold was fabricated by sequential electrospinning of blends of elastin/gelatin, PDS/elastin/gelatin, and PDS/gelatin (EG/PEG/PG) to mimic the complex matrix structure of native arteries. Under hydrated state, the trilayer conduit exhibited tensile properties (tensile strength of 1.77,±,0.2,MPa and elastic modulus of 5.74,±,3,MPa with a failure strain of 75.08,±,10%) comparable to those of native arteries. In vitro degradation studies for up to 30 days showed about 40% mass loss and increase in crystallinity due to the removal of proteins and "cleavage-induced crystallization" of PDS. Biotechnol. Bioeng. 2009; 104: 1025,1033. © 2009 Wiley Periodicals, Inc. [source] | ||||||||||