Chameleon teeth develop as individual structures at a distance from the developing jaw bone during the prehatching period and also partially during the post-hatching period. However, in the adult, all teeth are fused together and tightly attached to the jaw bone by mineralized attachment tissue to form one functional unit. Tooth to bone as well as tooth to tooth attachments are so firm that if injury to the oral cavity occurs, several neighbouring teeth and pieces of jaw can be broken off. We analysed age-related changes in chameleon acrodont dentition, where ankylosis represents a physiological condition, whereas in mammals, ankylosis only occurs in a pathological context. The changes in hard-tissue morphology and mineral composition leading to this fusion were analysed. For this purpose, the lower jaws of chameleons were investigated using X-ray microcomputed tomography, laser-induced breakdown spectroscopy and microprobe analysis. For a long time, the dental pulp cavity remained connected with neighbouring teeth and also to the underlying bone marrow cavity. Then, a progressive filling of the dental pulp cavity by a mineralized matrix occurred, and a complex network of non-mineralized channels remained. The size of these unmineralized channels progressively decreased until they completely disappeared, and the dental pulp cavity was filled by a mineralized matrix over time. Moreover, the distribution of calcium, phosphorus and magnesium showed distinct patterns in the different regions of the tooth-bone interface, with a significant progression of mineralization in dentin as well as in the supporting bone. In conclusion, tooth-bone fusion in chameleons results from an enhanced production of mineralized tissue during post-hatching development. Uncovering the developmental processes underlying these outcomes and performing comparative studies is necessary to better understand physiological ankylosis; for that purpose, the chameleon can serve as a useful model species.

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Results of this study confirm the causative role of absorbable suture material in the pathogenesis of hollow channel structures in some canine compound uroliths.

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Matrix-matched calibration for quantitative elemental mapping of kidney stones by laser ablationinductively coupled plasma-mass spectrometry (LA-ICP-MS) was developed with a 213 nm Nd:YAG laser ablation device and a quadrupole mass spectrometer. The method was applied to the imaging of P, Na, Sr, Zn, Ba and Pb distributions over a section of the kidney stone specimen containing phosphate and oxalate phases. Eighteen kidney stone specimens consisting of phosphate, oxalate and urate phases in various proportions were cut into halves for both preparation of calibration pellets and bulk analysis.Homogeneity of calibration pellets was examined by scanning electron microscopy (SEM) and LA-ICP-MS, concluding that areas of individual biominerals were thoroughly mixed and their size in units of micrometers was well below the size of the used laser spot. Calcium was employed as the internal reference element, being present in sufficient contents in the studied kidney stones. Mean values of calcium contents in oxalate and phosphate phases separately were determined using an electron microprobe (EMP) in the kidney stone section further subjected to the mapping. The actual (time-and space-resolved) Ca sensitivity was computed for each 44 Ca + signal and used as the internal reference for LA-ICP-MS isotopic signals of P, Na, Sr, Zn, Ba and Pb when mapping. Dependences of particular isotopic signal intensity/Ca sensitivity ratios vs. average elemental contents by solution analysis were processed by ordinary least squares linear regression. Despite variable matrices the regression yielded calibration lines with insignificant intercepts, coefficients of determination R 2 > 0.9955, and relatively narrow prediction and confidence bands. However, in addition, the applicability of four-point calibration and four single-point calibrations as less time-consuming options was examined on the basis of the NIST SRM 1486 bone meal pellet analysis. Best fit was obtained for the four-point calibration and single-point calibration with the phosphate pellet. Quantitative elemental maps of the kidney stone section were recorded and computed for P, Na, Sr, Zn, Ba and Pb. The feasibility of quantification by matrix-matched single-point calibration was verified by determination of the median elemental contents in phosphate and oxalate phases by LA-ICP-MS and their arithmetic comparison mean values obtained over the same section area using EMP. IntroductionLaser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) has already been employed in various elds of scientic research such as biology, 1-4 medicine, 5-9 geology, 10,11 archaeology, 12-17 etc. The ability to focus the laser beam onto a sample area with size from units to thousands of square micrometers together with limits of detection down to units of JAAS PAPER milligrams per kilogram makes this method interesting for elemental mapping at the "microscale". For example, elemental distribution was studied in archaeological ndings, such as tooth and bone tissues, in order to reve...

Research in cell adhesion has important implications in various areas, such as food processing, medicine, environmental engineering, biotechnological processes. Cell surface characterization and immobilization of microorganisms on solid surfaces can be performed by promoting cell adhesion, in a relatively simple, inexpensive, and quick manner. The adhesion of Yarrowia lipolytica IMUFRJ 50682 to different surfaces, especially potential residual plastics (polystyrene, poly(ethylene terephthalate), and poly(tetrafluoroethylene)), and its use as an immobilized biocatalyst were tested. Y. lipolytica IMUFRJ 50682 presented high adhesion to different surfaces such as poly(tetrafluoroethylene) (Teflon), polystyrene, and glass, independent of pH, and low adhesion to poly(ethylene terephthalate) (PET). The adhesion of the cells to polystyrene was probably due to hydrophobic interactions involving proteins or protein complexes. The adhesion of the cells to Teflon might be the result not only of hydrophobic interactions but also of acid–basic forces. Additionally, the present work shows that Y. lipolytica cell extracts previously treated by ultrasound waves (cell debris) maintained their enzymatic activity (lipase) and could be attached to polystyrene and PET and used successfully as immobilized biocatalysts in hydrolysis reactions.

Surface coatings of materials by polysaccharide polymers are an acknowledged strategy to modulate interfacial biocompatibility. Polysaccharides from various algal species represent an attractive source of structurally diverse compounds that have found application in the biomedical field. Furcellaran obtained from the red algae Furcellaria lumbricalis is a potential candidate for biomedical applications due to its gelation properties and mechanical strength. In the present study, immobilization of furcellaran onto polyethylene terephthalate surfaces by a multistep approach was studied. In this approach, N-allylmethylamine was grafted onto a functionalized polyethylene terephthalate (PET) surface via air plasma treatment. Furcellaran, as a bioactive agent, was anchored on such substrates. Surface characteristics were measured by means of contact angle measurements, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Subsequently, samples were subjected to selected cell interaction assays, such as antibacterial activity, anticoagulant activity, fibroblasts and stem cell cytocompatibility, to investigate the Furcellaran potential in biomedical applications. Based on these results, furcellaran-coated PET films showed significantly improved embryonic stem cell (ESC) proliferation compared to the initial untreated material.