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Background: Platelet concentrates have been popularly used in regenerative periodontal therapy as they are autologous in origin and they provide a supernatural concentration of platelets, growth factors and leukocytes. The release profile of various growth factors is considered important during the various phases of wound healing with the most important being the inflammatory phase where the release of the growth factors help in recruitment of cells and in collagen production. With the more recent modifications of PRF namely A-PRF and T-PRF, the mechanical and chemical degradation properties have also improved. The aim of the present study was to correlate the release profile of PDGF-AA from various forms of platelet concentrates (L-PRF, A-PRF, T-PRF) based on their mechanical and chemical properties. Methods: Blood samples were drawn from 2 male and 3 female systemically healthy patients between 20 and 25 years of age who were about to undergo periodontal regeneration for PRF preparation. The blood sample was immediately centrifuged using a table top centrifuge (Remi R4C) at 1060 rpm (208 x g) for 14 min for A-PRF preparation, 1960 rpm (708 x g) for 12 min for L-PRF preparation and 1960 rpm (708 x g) for 12 min in titanium tubes for T-PRF preparation. Tensile test was performed using universal testing machine. The in vitro degradation test of the prepared PRF membranes were conducted by placing the PRF membrane in 10 ml of pH 7.4 PBS on an orbital shaker set at 50 rpm. SEM evaluation of the PRF membrane was done under both low and high magnification. In order to determine the amount of released growth factor PDGF-AA at 15 min, 60 min, 8 h, 1 day, 3 days, and 10 days, samples were placed into a shaking incubator at 37 °C to allow for growth factor release into the culture media. Results: On comparing the three PRF membranes, it was found that T-PRF contained the maximum tensile strength (404.61 ± 5.92 MPa) and modulus of elasticity (151.9 ± 6.92 MPa). Statistically significant differences between the three groups were found on comparing the groups for their mechanical properties. In the degradation test, it was found that the maximum amount of degradation was found in L-PRF (85.75%), followed by A-PRF (84.18%) and the least was found in T-PRF (82.27%). T-PRF released the highest amount of PDGF-AA (6060.4 pg/ml) at early time points when compared to A-PRF (5935.3 pg/ml). While T-PRF had rapid release of PDGF-AA, A-PRF had a sustained release of growth factors released at later time points. Conclusion: Results from the present study indicate that A-PRF is the most favourable form of platelet concentrate in regenerative periodontal therapy as it has a sustained release of growth factors over time.
An in vitro cell study evaluating cell adhesion to hydroxyapatite (HA) coated prosthetic Ti-6Al-4V alloy via laser treatment is presented in comparison with uncoated alloy. Based on our previous in vitro biocompatibility study, which demonstrated higher cell attachment and proliferation with MC3T3-E1 preosteoblast cells, the present investigation aims to reveal the effect of laser coating Ti alloy with HA on the adhesion strength of bone-forming cells against centrifugal forces. Remaining cells on different substrates after centrifugation were visualized using fluorescent staining. Semi-quantifications on the numbers of cells were conducted based on fluorescent images, which demonstrated higher numbers of cells retained on HA laser treated substrates post centrifugation. The results indicate potential increase in the normalized maximum force required to displace cells from HA coated surfaces versus uncoated control surface. The possible mechanisms that govern the enhancing effect were discussed, including surface roughness, chemistry, wettability, and protein adsorption. The improvement in cell adhesion through laser treatment with a biomimetic coating could be useful in reducing tissue damage at the prosthetic to bone junction and minimizing the loosening of prosthetics over time.
The in-situ measurement of dilution during the laser surface alloying process is an enormously difficult task, due to the localized nature of laser energy and very short laser-material interaction time. Therefore, a computational approach (finite-element method and analysis of variance) was effectively employed to evaluate the dilution during the laser surface alloying process. Firstly, a finiteelement model based on COMSOL™ multiphysics was developed to predict the dilution of Mo with Al during non-equilibrium laser surface alloying process. Secondly, the optimization model based on Design-Expert® was developed to find the optimal laser surface alloying parameters (laser power, scanning speed, and fill spacing) to obtain a microstructure suitable for improved corrosion resistance that is primarily attributed to the formation of Al5Mo intermetallic phase (16.7 at% Mo). The present optimization model utilized the prior experimental and computational (finite-element) modeling data for the concentration of Mo (at%). The optimization analyses were carried out for the all the current datasets and the analysis revealed 44 optimal solutions that indicate the highest desirability. The confirmation runs were carried out to validate the optimization model. The experimental observation showed that the sample processed with optimal processing conditions demonstrates good corrosion resistance.
Madhaiyan, Munusamy,Poonguzhali, Selvaraj,Lee, Jung-Sook,Saravanan, Venkatakrishnan Sivaraj,Lee, Keun-Chul,Santhanakrishnan, Palani Microbiology Society 2010 International journal of systematic and evolutiona Vol.60 No.7
<P>A methylotrophic nitrogen-fixing bacterial strain, Ah-143<SUP>T</SUP>, isolated from the rhizosphere soil of field-grown groundnut was analysed by a polyphasic taxonomic approach. Comparative 16S rRNA gene sequence analysis combined with <I>rpoB</I> gene sequence analysis allocated strain Ah-143<SUP>T</SUP> to the family <I>Enterobacteriaceae</I>, with <I>Enterobacter radicincitans</I> and <I>Enterobacter cowanii</I> as the closest relatives. The strain is Gram-stain-negative, non-spore-forming, aerobic and motile, having straight rod-shaped cells with a DNA G<I>+</I>C content of approximately 53.2 mol%. The strain utilizes methanol as a carbon source and the <I>mxaF</I> gene was closely related to the <I>mxaF</I> gene of members of the genus <I>Methylobacterium</I>. The fatty acid profile consisted of C16 : 0, C17 : 0 cyclo, C18 : 1<I>ω</I>7<I>c</I>, summed feature 2 (iso-C16 : 1 I and/or C14 : 0 3-OH) and summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1<I>ω</I>7<I>c</I>) as the major components. DNA-DNA relatedness of strain Ah-143<SUP>T</SUP> with its close relatives was less than 20 %. On the basis of the phylogenetic analyses, DNA-DNA hybridization data, and unique physiological and biochemical characteristics, it is proposed that the strain represents a novel species of the genus <I>Enterobacter</I> and should be named <I>Enterobacter arachidis</I> sp. nov. The type strain is Ah-143<SUP>T</SUP> (=NCIMB 14469<SUP>T</SUP> =KCTC 22375<SUP>T</SUP>).</P>
Madhaiyan, Munusamy,Poonguzhali, Selvaraj,Lee, Jung-Sook,Lee, Keun-Chul,Saravanan, Venkatakrishnan Sivaraj,Santhanakrishnan, Palani Microbiology Society 2010 International journal of systematic and evolutiona Vol.60 No.7
<P><I>Microbacterium</I> strain AI-S262<SUP>T</SUP> was isolated from the rhizoplane of neem seedlings in the Botanical garden of Tamilnadu Agricultural University, Coimbatore, India, and subjected to phenotypic, chemotaxonomic and genetic characterization. Cells of this strain were Gram-stain-positive, motile, non-spore-forming, short rods and formed light-yellow-pigmented colonies on nutrient agar. Strain AI-S262<SUP>T</SUP> contained MK-12 and MK-13 as the main respiratory quinones, anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0 as the predominant fatty acids, peptidoglycan-type B2<I>β</I> with glycolyl residues, and had a DNA G+C content of 69.5 mol%. A phylogenetic analysis based on 16S rRNA gene sequences showed 98.0-98.6 % pair-wise similarity with respect to close relatives in the genus <I>Microbacterium</I>. DNA-DNA hybridization experiments revealed a low level of DNA-DNA relatedness (less than 39%) between strain AI-S262<SUP>T</SUP> and its closest relatives. Data from DNA-DNA hybridization and phenotypic analyses supported the conclusion that strain AI-S262<SUP>T</SUP> represents a novel species in the genus <I>Microbacterium</I>, for which the name <I>Microbacterium azadirachtae</I> sp. nov. is proposed. The type strain is AI-S262<SUP>T</SUP> (=JCM 15681<SUP>T</SUP> =LMG 24772<SUP>T</SUP> =KCTC 19668<SUP>T</SUP>).</P>