Electrospun Small-Diameter Silk Fibroin Vascular Grafts with Tuned Mechanical and Biocompatibility Properties as Tissue Engineered Scaffolds

Almost 9 million people in the U.S. have peripheral arterial disease (PAD). In severe cases of PAD, arterial bypass surgery is performed to redirect flow around the problem area. However, for many elderly patients, this surgery is not feasible using the preferred autologous grafts because of the limited availability of tissue to use for grafting, so there is a clinical need for engineered vascular grafts. Engineered grafts are intended to replace native blood vessels by manipulating biomaterials to mimic the properties of the native vessel. Despite success in large diameter cases, small diameter grafts are still prone to a number of issues such as occlusion, hyperplasia, and thrombosis. Silk fibroin is a promising biomaterial for creating vascular grafts because of its demonstrated mechanical strength and biocompatibility. Our research established a method for electrospinning the silk fibroin onto a rotating mandrel for seamless grafts. Mechanical testing, including burst pressure and tensile strength tests, compared the strength of our grafts to that of the autologous vessel. Finally, biochemical modifications, aimed at both recruiting and proliferating HUVECs on the grafts, increased cell proliferation on the grafts in vitro

Comparative evaluation of direct plating and most probable number for enumeration of low levels of Listeria monocytogenes in naturally contaminated ice cream products

AbstractA precise and accurate method for enumeration of low level of Listeria monocytogenes in foods is critical to a variety of studies. In this study, paired comparison of most probable number (MPN) and direct plating enumeration of L. monocytogenes was conducted on a total of 1730 outbreak-associated ice cream samples that were naturally contaminated with low level of L. monocytogenes. MPN was performed on all 1730 samples. Direct plating was performed on all samples using the RAPID'L.mono (RLM) agar (1600 samples) and agar Listeria Ottaviani and Agosti (ALOA; 130 samples). Probabilistic analysis with Bayesian inference model was used to compare paired direct plating and MPN estimates of L. monocytogenes in ice cream samples because assumptions implicit in ordinary least squares (OLS) linear regression analyses were not met for such a comparison. The probabilistic analysis revealed good agreement between the MPN and direct plating estimates, and this agreement showed that the MPN schemes and direct plating schemes using ALOA or RLM evaluated in the present study were suitable for enumerating low levels of L. monocytogenes in these ice cream samples. The statistical analysis further revealed that OLS linear regression analyses of direct plating and MPN data did introduce bias that incorrectly characterized systematic differences between estimates from the two methods