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The field of biofabrication continues to progress, offering higher levels of spatial control, reproducibility, and functionality. However, we remain far from recapitulating what nature has achieved. Biological systems such as tissues and organs are assembled from the bottom-up through coordinated supramolecular and cellular processes that result in their remarkable structures and functionalities. In this perspective, we propose that incorporating such biological assembling mechanisms within fabrication techniques, offers an opportunity to push the boundaries of biofabrication. We dissect these mechanisms into distinct biological organization principles (BOPs) including self-assembly, compartmentalization, diffusion-reaction, disorder-to-order transitions, and out-of-equilibrium processes. We highlight recent work demonstrating the viability and potential of these approaches to enhance scalability, reproducibility, vascularization, and biomimicry; as well as current challenges to overcome., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

An analysis of the material properties of porcine corneas has been performed. A simple stress relaxation test was performed to determine the viscoelastic properties and a rheological model was built based on the Generalized Maxwell (GM) approach. A validation experiment using nano-indentation showed that an isotropic GM model was insufficient for describing the corneal material behaviour when exposed to a complex stress state. A new technique was proposed for determining the properties, using a combination of nano-indentation experiment, an isotropic and orthotropic GM model and inverse finite element method. The good agreement using this method suggests that this is a promising technique for measuring material properties in vivo and further work should focus on the reliability of the approach in practice., (© 2013 Elsevier Ltd. All rights reserved.)

A new metallic atomization cell is used for trace metal determinations by tungsten coil atomic absorption spectrometry and tungsten coil atomic emission spectrometry. Different protecting gas mixtures are evaluated to improve atomic emission signals. Ar, N(2), CO(2) and He are used as solvents, and H(2) and C(2)H(2) as solutes. A H(2)/Ar mixture provided the best results. Parameters such as protecting gas flow rate and atomization current are also optimized. The optimal conditions are used to determine the figures of merit for both methods and the results are compared with values found in the literature. The new cell provides a better control of the radiation reaching the detector and a small, more isothermal environment around the atomizer. A more concentrated atomic cloud and a smaller background signal result in lower limits of detection using both methods. Cu (324.7 nm), Cd (228.8 nm) and Sn (286.3 nm) determined by tungsten coil atomic absorption spectrometry presented limits of detection as low as 0.6, 0.1, and 2.2 μg L(-1), respectively. For Cr (425.4 nm), Eu (459.4 nm) and Sr (460.7 nm) determined by tungsten coil atomic emission spectrometry, limits of detection of 4.5, 2.5, and 0.1 μg L(-1) were calculated. The method is used to determine Cu, Cd, Cr and Sr in a water standard reference material. Results for Cu, Cd and Cr presented no significant difference from reported values in a 95% confidence level. For Sr, a 113% recovery was obtained., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Vascular calcification is associated with an adverse prognosis in end-stage renal disease. It can be accurately quantitated with computed tomography but simple in-office techniques may provide equally useful information. Accordingly we compared the results obtained with simple non-invasive techniques with those obtained using electron beam tomography (EBT) for coronary artery calcium scoring (CACS) in 140 prevalent hemodialysis patients. All patients underwent EBT imaging, a lateral X-ray of the lumbar abdominal aorta, an echocardiogram, and measurement of pulse pressure (PP). Calcification of the abdominal aorta was semiquantitatively estimated with a score (Xr-score) of 0-24 divided into tertiles, echocardiograms were graded as 0-2 for absence or presence of calcification of the mitral and aortic valve and PP was divided in quartiles. The CACS was elevated (mean 910+/-1657, median 220). The sensitivity and specificity for CACS > or = 100 was 53 and 70%, for calcification of either valve and 67 and 91%, respectively, for Xr-score > or = 7. The area under the curve for CACS > or = 100 associated with valve calcification and Xr-score was 0.62 and 0.78, respectively. The likelihood ratio (95% confidence interval) of CACS > or = 100 was 1.79 (1.09, 2.96) for calcification of either valve and 7.50 (2.89, 19.5) for participants with an Xr-score > or = 7. In contrast, no association was present between PP and CACS. In conclusion, simple measures of cardiovascular calcification showed a very good correlation with more sophisticated measurements obtained with EBT. These methodologies may prove very useful for in-office imaging to guide further therapeutic choices in hemodialysis patients.

The effects of exercise on morphine-induced analgesia were examined in male and female Long-Evans rats. In Experiment 1, 10 male rats were housed in standard laboratory cages, and 10 in activity wheels for 20 days prior to nociceptive testing. Pain thresholds were assessed using a tail-flick (TF) procedure. Morphine sulfate was administered using a cumulative dosing procedure (2.5, 5.0, 7.5, 10.0, 12.5, and 15.0 mg/kg). TF latencies were measured immediately prior to and 30 min following each injection. In Experiment 2, morphine-induced analgesia was examined in females in an identical manner to that of Experiment 1. Additionally, to determine if the attenuation of morphine-induced analgesia was permanent or reversible, after the initial test nociceptive test, previously active female rats were placed in standard cages, and previously inactive females placed in running wheels for 17 days prior to a second nociceptive test. Baseline TF latencies were significantly shorter in active male rats than in inactive animals. Additionally, both active male and female rats displayed decreased morphine-induced analgesia relative to inactive controls. Moreover, females that had been inactive and then were permitted to run showed a suppression in morphine-induced analgesia relative to presently inactive rats, and to their own nociceptive responses when sedentary. In contrast, morphine-induced analgesia in initially active females who were housed in standard cages during part 2 of Experiment 2 was enhanced relative to their first nociceptive test and to presently active rats. Experiment 3 examined the effects of short-term (24 h) running on antinociception. Baseline TF latencies were shorter in active rats than inactive rats. However, no differences in morphine-induced analgesia were observed as a function of short-term exposure to exercise. Experiment 4 investigated whether differences in body weight contributed to the differences in morphine-induced analgesia between chronically active and inactive animals. %MPEs did not vary among male rats maintained at 100, 85, or 77% of their free-feeding body weight. These results indicate that chronic activity can decrease morphine's analgesic properties. These effects may be due to crosstolerance between endogenous opioid peptides released during exercise and exogenous opioids.

The objective of this study was to determine if a high fat diet having a 2:1 saturated-polyunsaturated fatty acid ratio exacerbates signs of copper deficiency. Male weanling Long-Evans rats were randomly placed into one of the following treatment groups: adequate copper low fat or deficient copper high fat. The levels of fat used were 31 or 12% of daily energy, and copper concentrations were 94.5 micromol/kg and <15.8 micromol/kg in the copper-adequate and copper-deficient diets, respectively. Cardiac hypertrophy as well as lower liver copper levels and superoxide dismutase activity were observed in both groups of copper-deficient rats. Irrespective of copper level, consumption of the high fat diet resulted in the thickening of the interventricular septum and left ventricular free wall. Electrocardiograms revealed that the copper-deficient high fat diet led to a significantly smaller QT interval compared with all other groups. Significantly greater S-wave voltage due to copper deficiency was observed. Significantly lower heart cytochrome c oxidase (CCO) activity was found in the copper-deficient groups with the copper deficient high fat group showing the lowest activity. Western blots of the cardiac non-myofibrillar fraction demonstrated lower amounts of CCO nuclear encoded peptides in the copper-deficient groups, with the least amount seen in the copper-deficient high fat treatment. These data suggest that a high level of dietary fat exacerbates some of the signs of copper deficiency.