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1.  Requirement for Both Micron and Submicron Scale Structure for Synergistic Responses of Osteoblasts to Substrate Surface Energy and Topography 
Biomaterials  2007;28(18):2821-2829.
Objective
Surface roughness and surface free energy are two important factors that regulate cell responses to biomaterials. Previous studies established that titanium substrates with micron-scale and submicron scale topographies promote osteoblast differentiation and osteogenic local factor production and that there is a synergistic response to microrough Ti surfaces that have retained their high surface energy via processing that limits hydrocarbon contamination. This study tested the hypothesis that the synergistic response of osteoblasts to these modified surfaces depends on both surface microstructure and surface energy.
Methods
Ti disks were manufactured to present three different surface structures: smooth pretreatment surfaces (PT) with Ra of 0.2 µm; acid-etched surfaces (A) with a submicron roughness Ra of 0.83 µm; and sandblasted/acid-etched surfaces (SLA) with Ra of 3–4 µm. Modified acid-etched (modA) and modified sandblasted/acid-etched (modSLA) titanium substrates, which have low contamination and present a hydroxylated/hydrated surface layer to retain high surface energy, were compared with regular low surface energy A and SLA surfaces. Human osteoblast-like MG63 cells were cultured on these substrates and their responses, including cell shape, growth, differentiation (alkaline phosphatase, osteocalcin), and local factor production (TGF-β1, PGE2, osteoprotegerin [OPG]) were analyzed (N=6 per variable). Data were normalized to cell number.
Results
There were no significant differences between smooth PT and A surfaces except for a small increase in OPG. Compared to A surfaces, MG63 cells produced 30% more osteocalcin on modA, and 70% more on SLA. However, growth on modSLA increased osteocalcin by more than 250%, which exceeded the sum of independent effects of surface energy and topography. Similar effects were noted when levels of latent TGF-β1, PGE2 and OPG were measured in the conditioned media.
Conclusions
The results demonstrate a synergistic effect between high surface energy and topography of Ti substrates and show that both micron scale and submicron scale structural features are necessary.
doi:10.1016/j.biomaterials.2007.02.024
PMCID: PMC2754822  PMID: 17368532
Titanium; Surface energy; Microstructure; Submicron roughness; Osteoblast differentiation
2.  Cultural Characteristics and Fatty Acid Composition of Propionibacteria 
Journal of Bacteriology  1969;97(2):561-570.
The cultural characteristics and cellular fatty acid composition of 40 strains representing 7 species of Propionibacterium and of 9 cultures of anaerobic corynebacteria were studied. The cultures were characterized by means of 23 separate cultural and biochemical tests. Cultures of the two genera differed consistently in only two reactions; the propionibacteria did not produce indole or liquefy gelatin, whereas the anaerobic corynebacteria were consistently positive with these tests. The fatty acids were extracted from whole cells and examined as methyl esters by gas-liquid chromatography. The most abundant acid in the seven Propionibacterium species was a C15-saturated branched-chain acid which was present in both the iso-and anteiso-form. Based on a comparison of the relative abundance of these isomers (i-C15 and a-C15), the species were separated into two groups. P. freudenreichii and P. shermanii (group one) were similar and contained the a-C15 isomer as the predominant acid. The i-C15 isomer was the most abundant acid in the second group (P. arabinosum, P. jensenii, P. pentosaceum, P. thoenii, and P. zeae). The fatty acid profiles of the anaerobic corynebacteria were somewhat similar to those of the second group of propionibacteria, but were distinct from the profiles of P. freudenreichii and P. shermanii. The addition of branched-chain amino acids (l-leucine and l-isoleucine) to the growth medium increased the synthesis of the specific fatty acid(s) structurally related to the added amino acid.
PMCID: PMC249728  PMID: 4886285
3.  Fatty acids of Listeria monocytogenes. 
Journal of Bacteriology  1968;96(6):2175-2177.
PMCID: PMC252578  PMID: 4972921

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