PubMed · 13261156
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T F TIERNEY. 1955. The right base.. https://pubmed.ncbi.nlm.nih.gov/13261156/
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An in situ gel system was developed to encapsulate chondrocytes under physiological conditions using an alkali-treated collagen (AlCol) and pentaerythritol poly(ethylene glycol) ether tetrasuccinimidyl glutarate (4S-PEG) as a crosslinker. AlCol gels were obtained at crosslinker concentrations from 0.1 to 3.0 mM. Chondrocytes were encapsulated and dispersed homogeneously in AlCol gels. Results of MTT staining showed that cells survived after encapsulation in AlCol gels. Biochemical analysis demonstrated that DNA content in AlCol gels was constant after 3 weeks. Glycosaminoglycan content and mRNA expression of type II collagen and aggrecan increased with culture time. These results suggest that this in situ gel system is useful for regenerating cartilage in vitro and for minimally invasive therapy for cartilage defects.
This study sought to evaluate osteoconduction of Ti-6Al-4V surfaces under various conditions, including micro-patterned, alkali-treated, micro-patterned plus alkali-treated, and surfaces without any treatment as the control. The through-mask electrochemical micromachining (EMM) was used to fabricate micro-hole arrays on the titanium alloy surface. In vitro calcium phosphate formation on titanium surfaces was in static and dynamic simulated body fluid (SBF). In vivo comparison was conducted in the medullary cavity of dog femur using the implant cages which could provide the same physiological environment for specimens with different surface conditions. In vitro experiments indicate good conduction of calcium phosphate on the alkali-treated surfaces, and also better calcium phosphate deposition on the micro-hole surface than on the flat surfaces in dynamic SBF. In vivo experiments confirm the beneficial effect of alkaline treatment on osteoconduction. The results of in vivo experiments also indicate a synergistic effect of the alkaline treatment and the topographic pattern on osteoconduction.
Nearly all of the reported studies of reactions of sulfate diesters are for dialkyl or alkyl aryl diesters, which undergo reaction by carbon-oxygen bond fission. Sulfuryl transfer reactions of sulfate diesters (RO-SO(2)-OR') proceeding by attack at sulfur have been little explored. When both ester groups are aryl groups the hydrolysis reaction (sulfuryl transfer to water) occurs by way of attack at sulfur. The alkaline hydrolysis of diaryl sulfate diesters was shown to obey first-order kinetics with respect to [(-)OH] and proceed through S-O bond fission, in a mechanism that is most likely concerted. Activation parameters for 4-chloro-3-nitrophenyl phenyl sulfate and 4-nitrophenyl phenyl sulfate gave the following respective values: Delta H(++) = 88.0 +/- 0.1 and 84.83 +/- 0.06 kJ mol(-)(1) and Delta S(++) = -37 +/- 1 and -50.2 +/- 0.5 J mol(-)(1) deg(-)(1). The dependence of the second-order rate constant for hydrolysis on leaving group pK(a) was analyzed giving a beta(lg) slope of -0.7 +/- 0.2 and a Leffler alpha parameter value of 0.36. A (15)k kinetic isotope effect (KIE) for the hydroxide attack on 4-nitrophenyl phenyl sulfate of 1.0000 +/-0.0005 and an (18)k(lg) KIE value of 1.003+/-0.002 were obtained.