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Precisely engineering the surface chemistry of biomaterials to modulate the adsorption and functionality of biochemical signaling molecules that direct cellular functions is critical in the development of tissue engineered scaffolds. Specifically, this study describes the use of functionalized self-assembled monolayers (SAMs) as a model system to assess the effects of biomaterial surface properties on controlling fibronectin (FN) conformation and concentration as well as keratinocyte function. By systematically analyzing FN adsorption at low and saturated surface densities, we distinguished between SAM-dependent effects of FN concentration and conformation on presenting cellular binding domains that direct cellular functions. Quantitative image analyses of immunostained samples showed that modulating the availability of the FN synergy site directly correlated with changes in keratinocyte attachment, spreading, and differentiation, through integrin-mediated signaling mechanisms. The results of this study will be used to elucidate design features that can be incorporated into dermal equivalents and percutaneous implants to enhance the rate of re-epithelialization and tissue regeneration. Furthermore, these findings indicate that SAM-based model systems are a valuable tool for designing and investigating the development of scaffolds that regulate the conformation of extracellular matrix cues and cellular functions that accelerate the rate of tissue regeneration. [ABSTRACT FROM AUTHOR]

To control postpartum anestrus and reduce calving to conception interval, 167 crossbred non-pregnant cows that were 90-130 days postpartum were allotted randomly to one of the following treatments: PH (n=59), intra-vaginal sponge with 250 mg of medroxyprogesterone acetate (MAP) for 7 days plus 50mg of MAP and 5mg 17-beta estradiol (17beta-E) in the first day of treatment (day -8), 500 UI eCG (day -3) and 1.5mg 17beta-E in 24h after sponge removal (day 0); CR (n=57), temporary calf removal for 120 h; CG (n=51), control group without treatment. Estrus rate differed among treatments (P<0.01) being greater in PH (78.2%), followed by CR (52.0%) and CG (22.9%). A greater proportion of cows in the PH (80.0%) and CR (54%) groups had ovulations when compared to CG (35.4%). Intervals to first estrus were 13.5+/-6.3 days, 26.1+/-6.4 days and 52.5+/-7.5 days for the PH, CR and CG groups, respectively. First insemination conception was similar in the three groups. Postpartum intervals to first breeding (PFS) and to conception (PCI) were longer in CG than PH and CR groups (P<0.05; P<0.01). The PH and CR groups had a similar PFS but PCI was different (P<0.02). Accumulated pregnancy rate at 30 and 60 but not at 90 days were different (30 days: P<0.09; P<0.01; P<0.09; 60 days: P<0.06; P<0.01; P<0.03) among treatments. After 90 days post-treatment, 9%, 18% and 33% of cows from the PH, CR and CG groups had not conceived. Similarly, 5.4%, 6.0% and 12.5% of cows from the PH, CR and CG groups, respectively, were culled from the herd because of lack of pregnancy after 180 days post treatment. In the group of cows evaluated by ultrasonography, only those cows having larger ovaries and dominant follicles had ovulations. It was concluded that the hormonal treatment was more efficient in inducing a fertile estrus and reducing calving to conception interval followed by the calf removal for 120 h. Each method can be considered as an important tool to reduce the postpartum anestrous period in dual purpose herds when AI is conduct in the tropics.