Investigating pore-opening in hydrogel foams at the scale of free-standing thin films

Controlling the pore connectivity of polymer foams is key for most of their applications, ranging from liquid uptake, mechanics, and acoustic/thermal insulation to tissue engineering. Despite its importance, the scientific phenomena governing the pore-opening processes remain poorly understood, requiring tedious trial-and-error procedures for property optimisation. This lack of understanding is partly explained by the high complexity of the different interrelated, multi-scale processes which take place as the foam transforms from an initially fluid foam into a solid foam. To progress in this field, we take inspiration from long-standing research on liquid foams and thin films to develop model experiments in a microfluidic "Thin Film Pressure Balance". These experiments allow us to investigate isolated thin films under well-controlled environmental conditions reproducing those arising within a foam undergoing cross-linking and drying. Using the example of alginate hydrogel films, we correlate the evolution of isolated thin films undergoing gelation and drying with the evolution of the rheological properties of the same alginate solution in bulk. We introduce the overall approach and use a first set of results to propose a starting point for the phenomenological description of the different types of pore-opening processes and the classification of the resulting pore-opening types. This article is protected by copyright. All rights reserved.

Hydrogel foams from liquid foam templates: Properties and optimisation

Hydrogel foams are an important sub-class of macroporous hydrogels. They are commonly obtained by integrating closely-packed gas bubbles of 10-1000 μm into a continuous hydrogel network, leading to gas volume fractions of more than 70% in the wet state and close to 100% in the dried state. The resulting wet or dried three-dimensional architectures provide hydrogel foams with a wide range of useful properties, including very low densities, excellent absorption properties, a large surface-to-volume ratio or tuneable mechanical properties. At the same time, the hydrogel may provide biodegradability, bioabsorption, antifungal or antibacterial activity, or controlled drug delivery. The combination of these properties are increasingly exploited for a wide range of applications, including the biomedical, cosmetic or food sector. The successful formulation of a hydrogel foam from an initially liquid foam template raises many challenging scientific and technical questions at the interface of hydrogel and foam research. Goal of this review is to provide an overview of the key notions which need to be mastered and of the state of the art of this rapidly evolving field at the interface between chemistry and physics.

Risk of biliary complications in bariatric surgery

Gallstones are commonly observed after rapid weight loss, particularly after bariatric surgery. Preventive measures of gallstone formation and potential related complications are still debated. This study aimed to propose a standardized strategy according to the results of the literature. Thus, preventive measures should be determined according to patient status (evaluated clinically and by routine ultrasound) and the type of bariatric surgery. Cholecystectomy should be performed in patients with symptomatic gallstones irrespective of the planned operation, or for asymptomatic gallstones during a gastric by-pass. In other settings, ursodesoxycholic acid should be given postoperatively for 6 months.

The effect of opioids and their antagonists on the nocifensive response of Caenorhabditis elegans to noxious thermal stimuli

Opiates modulate nociception in vertebrates. This has also been demonstrated in a number of invertebrate models. Herein, the effect of the opiate morphine and opioid neuropeptides Endomorphin 1 and 2 on the thermal avoidance (Tav) behavior of Caenorhabditis elegans is explored. Adult wild-type C. elegans N2 were collected from NGM plates using M9 buffer and exposed to morphine and endomorphine 1 and 2 in concentrations between 10(-8) and 10(-4) M (2.5 pmol/mg to 25 nmol/mg) for 30 min and tested for Tav. The opioid receptor antagonists Naloxone and CTOP were tested in combination with the drugs. Forty-seven percentage of the morphine exposed worms exhibited a class I response versus 76% of the control group (P < 0.001). Endomorphin 1 and 2 also caused a statistically significant reduction in class I responses, 36 and 39%, respectively. These effects were reversed with Naloxone and CTOP. Thermonocifensive behavior in C. elegans is modulated by opioids.

Lingual thyroid. A case report

We describe an unusual clinical case in which a non functional cervical thyroid coexisted with a functional ectopic lingual thyroid. A twenty-year-old woman was referred for hypothyroidism treated with L-thyroxin related to a basilingual tumor diagnosed 8 years previously. Oropharyngeal examination showed a spherical basilingual tumor 2.5 cm in diameter. Laboratory findings during treatment with 50 microgram of L-thyroxin daily showed: TSH 6,280 microIU/ml (N: 4,4 to 3.6), FT3 4,2 pmol/l (N: 3.3 to 5.1), and FT4 15.4 pmol/l (N: 10,5 to 25,5). Antithyroid antibodies were absent. Cervical ultrasonography showed a small hypoechogenic, heterogeneous orthotopic thyroid gland confirmed by cervical computed tomography thyroid. An I(123) scan revealed uptake above the chin on the profile, and no significant uptake is the area of the normal thyroid. The lack of iodine uptake by the cervical thyroid remains unexplained. In conclusion, this report of an ectopic thyroid location in unusual because of the coexistence of non functional cervical thyroid and of a partially functional lingual thyroid tissue. The pathogenesis of this association remains unclear.