On arginine-based polyurethane-blends specific to vascular prostheses

Polymer blends based on Tecoflex™ and an experimental aliphatic polyurethane (HMDI-PCL-arginine stands for 4,4 (metylene-biscyclohexyl) isocyanate - poly (ε caprolactone) diol, SPUUR stands for segmented poly(urea)urethanes using amino acid of L-Arginine as chain extender) were obtained by solvent casting, and further studied by fourier transform infrared (FTIR) and Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, and X-ray diffraction (XRD). Their biological performances were assessed in terms of hemocompatibility and Human umbilical vein endothelial cell (HUVEC) cytotoxicity. Tensile properties of dumbbell specimens were compared to longitudinal and circumferential tensile properties of tubular vascular graft. FTIR showed that as the SPUUR content increased in the blend, absorptions at 2860 cm⁻¹ increased, carbonyl absorptions at 1724 cm⁻¹ broaden and the small peak at 2796 cm⁻¹, typical of Tecoflex™ disappeared. Raman spectroscopy showed that the low intensity carbonyl absorption at 1724 cm⁻¹ also increased with SPUUR content. DSC allowed detection of PCL soft segment melting (T_m = 50°C) in agreement with X-ray reflections at 21.3° and 23.6°, assigned to SPUUR. However, no improvements in thermal stability were detected by TGA by blending. The addition of SPUUR to Tecoflex™ improved hemocompatibility and HUVEC cytotoxicity. The vascular grafts performance showed that 40% SPUUR blends exhibited the highest force in the longitudinal test whereas 50% SPUUR blends showed the highest circumferential force. Pressure burst strength was higher than 1000 mmHg for all blends. Overall, these blends can be used for high caliber vascular grafts.     

Effects of benoxinate hydrochloride 0.4% on the morphological appearance of the cornea using confocal microscopy.

PURPOSE: To investigate whether benoxinate hydrochloride 0.4% used to make confocal microscopy more comfortable alters the morphology of the cornea as viewed with the confocal microscope. METHODS: Confocal microscopy was performed on both eyes of 10 subjects prior to instillation of either topical anaesthetic or non-preserved sterile saline, on two randomly ordered occasions. Images of all corneal layers were analysed quantitatively and qualitatively in a masked fashion. RESULTS: The images were similar in appearance in 5/10 subjects, there was greater clarity when anaesthetic was instilled in 4/10 subjects, and in the remaining subject there was greater clarity when saline was used. Anaesthetic had no influence on anterior keratocyte density (AKD), posterior keratocyte density (PKD) or endothelial cell density (ECD). CONCLUSIONS: Local anaesthetic does not affect corneal morphology as imaged using the confocal microscope. However, failure to use anaesthetic may lead to a degradation of image quality due to patient discomfort and excessive eye movements.     

Temperature- and pH-sensitive core–shell nanogels as efficient carriers of doxorubicin with potential application in lung cancer treatment

Temperature- and pH-sensitive core–shell nanogels were prepared by one-pot soapless emulsion polymerization of N-isopropylacrylamide and 2-methacryloyloxy benzoic acid with the aid of a crosslinker (core) using poly(ethylene glycol) methyl ether methacrylate as stabilizer (shell). The size of nanogels depended on the crosslinker used, being considerable smaller (around 100?nm) with the use of the acid-labile crosslinker 9-divinyl-2,4,8,10-tetraoxaspiro[5.5]-undecane (DVA). Doxorubicine (DOX) was loaded in nanogels with good efficiency. The empty nanogels were biocompatible for a lung cancer cell line (NCI-H1437), while the DOX-loaded, DVA-crosslinked nanogels resulted with efficient cytotoxicity for that cell line.     

Effects of macroergonomic compatibility of information and communication technologies on the performance of manufacturing systems

Information and communication technologies (ICTs) have different effects depending on the companies that rely on them. On manufacturing systems, the effective use of ICTs requires a compatible design with the human, technology, and environment. This article analyses the effect of macroergonomic compatibility of ICTs as independent variable on dependent variables of production processes, clients, and organisational performance of manufacturing systems in the Mexican state of Chihuahua. In addition, this paper examines the relationships between these dependent variables. Methodology includes the construction of a questionnaire, administered to middle and senior managers of manufacturing companies to collect information on the macroergonomic practices of ICTs. Also, a factor analysis is carried out to data gathered, and hypotheses are proposed to suggest the effects of ICTs on dependent variables. Afterwards, a structural equations model is constructed and evaluated to test such hypotheses. Results obtained indicate that ICTs are an ideal element to measure macroergonomic compatibility of manufacturing systems, and that this compatibility has positive direct effects on production processes and clients, while significant indirect and total effects on the organisational performance of manufacturing systems. Results also showed that dependent variables clients and production processes had a significant impact on the performance of manufacturing systems.     

A systematic review/survey for JIT implementation: Mexican maquiladoras as case study

Mexico has a free trade agreement with the United States of America (USA) and Canada which was signed in 1988. This agreement created the conditions for establishing many foreign companies in several Mexican cities along the border zone between Mexico and USA. This strategy takes advantage of the geographic proximity with one of the biggest markets in the world, qualified manpower, and low production cost. With the arrival of those companies, frequently called Maquiladoras, a lot of production approaches have been introduced, and one of those widely applied is the just-in-time (JIT) production strategy. Despite the benefits of JIT, the interrelationship among several industrial factors and their impact on results derived from the implementation of JIT are unknown in Mexico. This is the underlying reason of this article, which aims at illustrating the results of a survey applied to foreign companies established in the Mexican–USA border. On the one hand, the activities developed by these companies during the implementation process of JIT are investigated and grouped as latent independent variables. These variables include organizational commitment, communication channels in organization, empowerment granted to employees, education provided in different organizational levels, and the capacity to solve problems, among others. On the other hand, the obtained benefits investigated are grouped as latent dependent variables. These dependent variables involve inventory management, quality, and cost, among others. Those aspects in the activities and benefits of the companies were evaluated using the structural equations model (SEM), which is useful to identify and analyze causal relationships. Result obtained from SEM indicates that management commitment and education are the main critical success factors in the JIT implementation, and that success can be measured through inventory, quality, and cost performance indicators.     

Confocal microscopy of the normal human cornea.

The slit-scanning confocal microscope is a new clinical paradigm that allows the living human cornea to be viewed at a magnification of 680 x and a lateral resolution of 1 mum. As such, it allows corneal morphology to be inspected at a cellular level. The corneas of both eyes of 119 subjects who were evenly distributed in age from 10-80 years were examined using a Tomey ConfoScan P4 in-vivo slit-scanning real-time confocal microscope (Erlangen, Germany). Good quality representative images of the various corneal layers were selected for detailed qualitative analysis and are displayed here. A grid of corneal layer versus age was constructed from these images; this tool can be used as a normative confocal microscopy reference against which suspected corneal abnormalities can be assessed.     

4-1BBL as a Mediator of Cross-Talk between Innate,Adaptive, and Regulatory Immunity against Cancer

The ability of tumor cells to evade the immune system is one of the main challenges we confront in the fight against cancer. Multiple strategies have been developed to counteract this situation, including the use of immunostimulant molecules that play a key role in the anti-tumor immune response. Such a response needs to be tumor-specific to cause as little damage as possible to healthy cells and also to track and eliminate disseminated tumor cells. Therefore, the combination of immunostimulant molecules and tumor-associated antigens has been implemented as an anti-tumor therapy strategy to eliminate the main obstacles confronted in conventional therapies. The immunostimulant 4-1BBL belongs to the tumor necrosis factor (TNF) family and it has been widely reported as the most effective member for activating lymphocytes. Hence, we will review the molecular, pre-clinical, and clinical applications in conjunction with tumor-associated antigens in antitumor immunotherapy, as well as the main molecular pathways involved in this association.