Antisera to H4-lactate dehydrogenase (LDH) were elicited in rabbits, against both human (h) and porcine (p) isoenzymes. 125I-labelled H4-LDH was prepared by electrolytic iodination. A simple and fast procedure (1-h incubation for clinical assays) was set up by using polyethylene glycol for the bound-free separation. The results obtained in the antiserum characterization indicated that the heterologous homotetramer, M4 was completely discriminated in the porcine system, while a weak cross-reaction with human antisera resulted. In both cases, for the hybrid forms, a cross-reactivity level related to the stoichiometric contents of the H-subunit in the tetramers was observed. The H4-LDH from other species was found to be much more effectively disinguished in the porcine than in the human system. The assay for human LDH was further validated in terms of analytical suitability and clinical response. For healthy subjects the mean concentration was 0.46+/-19 micrograms/ml (mean+/-SD). Patients with acute myocardial infarction had levels ranging from 1.2 to 5.9 micrograms/ml.
In response to the drawbacks of autograft donor-site morbidity and bone morphogenetic protein type 2 (BMP2) carcinogenesis and ectopic bone formation, there has been an increased research focus towards developing alternatives capable of achieving spatial control over bone formation. Here we show for the first time both osteogenic differentiation and mineralization (from solution or mediated by cells) occurring within predetermined microscopic patterns. Our results revealed that both PEGylated BMP2 and nacre proteins induced stem cell osteodifferentiation in microscopic patterns when these proteins were covalently bonded in patterns onto polyethylene glycol diacrylate (PEGDA) hydrogel substrates; however, only nacre proteins induced mineralization localized to the micropatterns. These findings have broad implications on the design and development of orthopedic biomaterials and drug delivery.
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