Rapid biofabrication of tubular tissue constructs by centrifugal casting in a decellularized natural scaffold with laser-machined micropores

Centrifugal casting allows rapid biofabrication of tubular tissue constructs by suspending living cells in an in situ cross-linkable hydrogel. We hypothesize that introduction of laser-machined micropores into a decellularized natural scaffold will facilitate cell seeding by centrifugal casting and increase hydrogel retention, without compromising the biomechanical properties of the scaffold. Micropores with diameters of 50, 100, and 200 mum were machined at different linear densities in decellularized small intestine submucosa (SIS) planar sheets and tubular SIS scaffolds using an argon laser. The ultimate stress and ultimate strain values for SIS sheets with laser-machined micropores with diameter 50 mum and distance between holes as low as 714 mum were not significantly different from unmachined control SIS specimens. Centrifugal casting of GFP-labeled cells suspended in an in situ cross-linkable hyaluronan-based hydrogel resulted in scaffold recellularization with a high density of viable cells inside the laser-machined micropores. Perfusion tests demonstrated the retention of the cells encapsulated within the HA hydrogel in the microholes. Thus, an SIS scaffold with appropriately sized microholes can be loaded with hydrogel encapsulated cells by centrifugal casting to give a mechanically robust construct that retains the cell-seeded hydrogel, permitting rapid biofabrication of tubular tissue construct in a "bioreactor-free" fashion.     

Human Herpesvirus-6 and -7 in the Brain Microenvironment of Persons with Neurological Pathology and Healthy People

During persistent human beta-herpesvirus (HHV) infection, clinical manifestations may not appear. However, the lifelong influence of HHV is often associated with pathological changes in the central nervous system. Herein, we evaluated possible associations between immunoexpression of HHV-6, -7, and cellular immune response across different brain regions. The study aimed to explore HHV-6, -7 infection within the cortical lobes in cases of unspecified encephalopathy (UEP) and nonpathological conditions. We confirmed the presence of viral DNA by nPCR and viral antigens by immunohistochemistry. Overall, we have shown a significant increase (p < 0.001) of HHV antigen expression, especially HHV-7 in the temporal gray matter. Although HHV-infected neurons were found notably in the case of HHV-7, our observations suggest that higher (p < 0.001) cell tropism is associated with glial and endothelial cells in both UEP group and controls. HHV-6, predominantly detected in oligodendrocytes (p < 0.001), and HHV-7, predominantly detected in both astrocytes and oligodendrocytes (p < 0.001), exhibit varying effects on neural homeostasis. This indicates a high number (p < 0.001) of activated microglia observed in the temporal lobe in the UEP group. The question remains of whether human HHV contributes to neurological diseases or are markers for some aspect of the disease process.     

Role of deoxyhemoglobin in lipid oxidation of washed cod muscle mediated by trout, poultry and beef hemoglobins

Deoxyhemoglobin content was measured in hemoglobins from trout, chicken and bovine sources between pH 5.5 and 7.5. With decreasing pH, deoxyhemoglobin content of trout was highest, low to intermediate in chicken, and lowest in beef hemoglobin. Each type of hemoglobin was added to washed cod muscle and lipid oxidation assessed during 2?°C storage. The lipid oxidation rate was trout > chicken > beef based on thiobarbituric reactive substances (TBARS) and lipid hydroperoxide formation. There was no significant difference in pro-oxidative activity of chicken compared to turkey hemoglobin. Hemoglobins from trout appeared to oxidize more rapidly compared to chicken hemoglobin in the washed cod muscle model system, as measured by a decrease in redness (a-value) during storage. Loss of red color was slowest in beef samples. These studies suggest that deoxyhemoglobin may be a major catalyst of lipid oxidation at post mortem pH values found in muscle foods, especially in fish and poultry compared to beef.     

Mixtures of vegetable oils and di‐2‐ethylhexyl‐sebacate as lubricants

Lubricants based on vegetable oils are growing in popularity in various applications. Environmentally friendly, vegetable oils and their derivatives constitute alternatives to mineral‐based lubricants. Soybean oil, sunflower oil and rapeseed oil have better viscosity indices than mineral oils and even some synthetic oils, are biodegradable and have low production costs. However, vegetable oils have disadvantages, such as poor thermo‐oxidative stability due to the carbon–carbon double bonds and poor low‐temperature properties, which limit their use as lubricant base stocks. This study describes new base‐stock oils obtained from mixture of vegetable oils and di‐2‐ethylhexyl‐sebacate synthetic oil, which become lubricants when additives are introduced. These mixtures offer a large range of kinematic viscosities, while their pour points are under −33°C and their flash points over 240°C. The copper strip corrosion test result is 1a. The diameters of wear scars measured under four‐ball testing (40dyn) are less than 1mm. A differential scanning calorimetry study and a thermo‐gravimetric study under a nitrogen atmosphere for the mixed oils are reported. In the former study two‐endothermic processes were observed between −15°C and −50°C. In the thermo‐gravimetric analysis curve the weight loss is specific for each vegetable and synthetic oil component. From these studies a higher thermal stability was observed for vegetable oils than for ester oils, and it was concluded that the mixtures of vegetable and synthetic oils of diester type are physically homogeneous mixtures. The low production cost of lubricants based on vegetable oils makes them attractive alternatives for mineral oil based lubricants. Overall the mixtures of vegetable and ester oils can be competitive base oils for environmentally friendly lubricants. Copyright © 2006 John Wiley & Sons, Ltd.