Additive manufacturing of tissues and organs

Additive manufacturing techniques offer the potential to fabricate organized tissue constructs to repair or replace damaged or diseased human tissues and organs. Using these techniques, spatial variations of cells along multiple axes with high geometric complexity in combination with different biomaterials can be generated. The level of control offered by these computer-controlled technologies to design and fabricate tissues will accelerate our understanding of the governing factors of tissue formation and function. Moreover, it will provide a valuable tool to study the effect of anatomy on graft performance. In this review, we discuss the rationale for engineering tissues and organs by combining computer-aided design with additive manufacturing technologies that encompass the simultaneous deposition of cells and materials. Current strategies are presented, particularly with respect to limitations due to the lack of suitable polymers, and requirements to move the current concepts to practical application.     

Oxidative stability of yogurt with added lutein dye

This study evaluated the effect of adding lutein dye on the oxidative stability of yogurt during 35 d of refrigerated storage, in the presence and absence of light. Yogurts manufactured without and with the equivalent of 1.5 mg of lutein in 120 g of the final product were characterized for their total carotenoid and riboflavin contents, and the behaviors of both riboflavin and lutein were monitored during storage. A decrease in riboflavin content occurred, with concurrent appearance of its derived-oxidation products in the yogurts without added lutein and exposed to light during storage. The yogurts with added lutein dye showed constant lutein and riboflavin contents throughout storage both for the samples stored under light and for those stored in the dark. Yogurts (120 g) with the addition of 0.5, 1.5, and 2.5 mg of lutein dye were evaluated for their sensory acceptance, and the statistical analysis showed no differences between the samples for the attributes of aroma and flavor. These results indicate that the added lutein remained stable throughout the storage period and conferred protection for the riboflavin against photooxidation, preserving the quality of the yogurts.     

Variables Controlling Stiffness and Strength of Lime-Stabilized Soils

Lime treatment is an attractive technique for soil improvement in the construction of rail tracks and pavement layers, in slope protection of earth dams, and as a support layer for shallow foundations. However, there are no dosage methodologies based on rational criteria as in the case of soil-cement technology, where the voids/cement ratio is shown to be a key parameter for the estimation of both strength and stiffness. The present study, therefore, was aimed at quantifying the influence of the amount of lime, porosity, and voids/lime ratio on the initial shear modulus (G0) and unconfined compressive strength (qu) of a lime-treated clayey sandy soil. From the results of unconfined compression tests and bender elements measurements, it was shown, for the soil-lime mixtures investigated, that the voids/lime ratio is an appropriate parameter to assess both initial stiffness and unconfined compressive strength. Also, a unique G0/qu versus voids/lime ratio relationship was established linking the soil-lime mixture initial stiffness and compressive strength.     

Moisture sorption isotherms and isosteric heat of sorption of coffee in different processing levels

The desorption isotherms and thermodynamic properties of coffee from different processing stages were obtained during the drying process of this product. The isotherms were determined by a static gravimetric method for various temperature and humidity conditions. Equilibrium moisture content (M_e) data were correlated by several mathematical models and an artificial neural network (ANN) model. The M_e for coffee fruits, pulped coffee and green coffee increased with an increase in the water activity (a_w) at any particular temperature. At a constant a_w, coffee fruits samples had higher M_e than the remaining coffee samples. Based on statistical parameters, the ANN model, modified Henderson and GAB models were adequate to describe the sorption characteristics of the samples. Isosteric heat of sorption was evaluated by means of the Clausius–Clapeyron equation. It decreased with increasing moisture content. The coffee fruits had higher isosteric heat of sorption than that pulped coffee and green coffee.     

Evaluation of an in Vitro Dissolution and Permeation Apparatus for Oral Solid Pharmaceutical Dosage Forms

An apparatus based in the USP dissolution test, the F-C-SL apparatus (Ferreira-Costa-Sousa Lobo), was developed that allowed the simultaneous evaluation of the in vitro release and permeation of oral solid pharmaceutical dosage forms. The release rate in both dissolution devices (USP and F-C-SL apparatus) was evaluated with acetaminophen tablets. Different test conditions (stirring rate and solvent volume ratio) were investigated and no significant differences in acetaminophen release rate were found between these apparatuses. In the F-C-SL apparatus, the in vitro permeation kinetics of acetaminophen were evaluated using synthetic membranes and followed a zero-order kinetic.     

Behavior of Plate Load Tests on Soil Layers Improved with Cement and Fiber

The load-settlement response from three plate load tests (300 mm diameter, 25.4 mm thick) carried out directly on a homogeneous residual soil stratum, as well as on a layered system formed by two different top layers (300 mm thick)—sand-cement and sand-cement fiber—overlaying the residual soil stratum, is discussed in this technical note. The utilization of a cemented top layer increased bearing capacity, reduced displacement at failure, and changed soil behavior to a noticeable brittle behavior. After maximum load, the bearing capacity dropped towards approximately the same value found for the plate test carried out directly on the residual soil. The addition of fiber to the cemented top layer maintained roughly the same bearing capacity but changed the postfailure behavior to a ductile behavior. A punching failure mechanism was observed in the field for the load test bearing on the sand-cement top layer, with tension cracks being formed from the bottom to the top of the layer. A completely distinct mechanism was observed in the case of the sand-cement-fiber top layer, the failure occurring through the formation of a thick shear band around the border of the plate, which allowed the stresses to spread through a larger area over the residual soil stratum.     

Comparative bioavailability of two immediate release tablets of cisapride in healthy volunteers

Irradiation of B16 pigmented melanoma subcutaneously transplanted in C57 mice with a single 650 mJ pulse (10 ns) of 1064 nm light from a Q-switched Nd: YAG laser caused instantaneous bleaching of the pigmented tissue. Visual and histological examination of the resulting gray-colored tumor revealed the breakdown of melanosomes with no detectable alteration of the normal and tumor-overlying skin. Histological examination of the irradiated tumor showed some degree of vascular damage; the depth of the photodamage was not affected by the successive delivery of three consecutive light pulses. The bleached tumor grew at a modestly slower rate but the high-peak-power (HPP) laser treatment did not affect the tumor concentration of a photodynamic sensitizer Si(i.v.)-naphthalocyanine (isoBO-SiNc) intravenously injected 24 h before Nd:YAG irradiation. Treatment of the B16 pigmented melanoma by photodynamic therapy (PDT: 1 mg/kg isoBO-SiNc, 300 mW/cm2, 520 J/cm2) from a 774 nm diode laser immediately after the 1064 nm irradiation resulted in a 16 day delay of tumor regrowth, which was markedly longer than the delay (ca 6 days) obtained after PDT under identical conditions without the preirradiation. Thus, pretreatment of pigmented tumors with HPP 1064 nm light appears to enhance their susceptibility to conventional PDT. The tumor response was further enhanced by repeating the combined HPP/PDT treatment at an interval of 10 days (regrowth delay: 27 days), as well as by applying hyperthermia immediately after HPP/PDT (regrowth delay: ca 34 days).     

BioCell Printing: Integrated automated assembly system for tissue engineering constructs

The production methodology of 3D constructs for tissue regeneration is usually a complex discontinuous process involving three different stages: (1) production of 3D matrices; (2) matrix sterilisation and cell seeding; (3) in vitro dynamic cell culture. This paper presents a novel automated bench-top manufacturing system called BioCell Printing, designed for the integrated, continuous and fully automated production and in vitro dynamic culture of tissue engineering constructs. The BioCell aims at the rapid production of tissue-engineered substitutes with low risk of contamination, increasing the chances of direct clinical application.