Intestinal Barrier in Human Health and Disease

The intestinal mucosa provides a selective permeable barrier for nutrient absorption and protection from external factors. It consists of epithelial cells, immune cells and their secretions. The gut microbiota participates in regulating the integrity and function of the intestinal barrier in a homeostatic balance. Pathogens, xenobiotics and food can disrupt the intestinal barrier, promoting systemic inflammation and tissue damage. Genetic and immune factors predispose individuals to gut barrier dysfunction, and changes in the composition and function of the gut microbiota are central to this process. The progressive identification of these changes has led to the development of the concept of ‘leaky gut syndrome’ and ‘gut dysbiosis’, which underlie the relationship between intestinal barrier impairment, metabolic diseases and autoimmunity. Understanding the mechanisms underlying this process is an intriguing subject of research for the diagnosis and treatment of various intestinal and extraintestinal diseases.

Effects of environmental temperature and humidity on evaporative heat loss through firefighter suit materials made with semi-permeable and microporous moisture barriers

The goal of this research was to understand how firefighter protective suits perform in different operational environments. This study used a sweating guarded hotplate to examine the effect of environmental temperature (20–45°C) and relative humidity (25–85% RH) on evaporative heat loss through firefighter turnout materials. Four firefighter turnout composites containing three different bi-component (semi-permeable) and one microporous moisture barriers were selected. The results showed that the evaporative resistance of microporous moisture barrier systems was independent of environmental testing conditions. However, absorbed moisture strongly affected evaporative heat loss through semi-permeable moisture barriers coated with a layer of nonporous hydrophilic polymer. Moisture absorption in mild environment (20–25°C) tests, or when testing at high humidity (>85% RH), significantly increased water vapor transmission in semi-permeable turnout systems. It was also found that environmental conditions used in the total heat loss (THL) test (25°C and 65% RH) produced moisture condensation in bi-component barrier systems, making them appear more breathable than could be expected when worn in hotter environments. Regression models successfully qualified the relationships between moisture uptake levels in semi-permeable barrier systems and evaporative resistance and THL. These findings reveal the limitations in relying on THL, the heat strain index currently called for by the NFPA 1971 Standard for Structural Firefighter personal protective equipment, and supports the need to measure turnout evaporative resistance at 35°C (Ret), in addition to THL at 25°C.

Novel Colour-Based, Prototype Indicator for Use in High-Pressure Processing (HPP)

The preparation and testing of a colour-based prototype indicator for high-pressure processing (HPP) are described. The indicator is a layered structure comprising a pressed disc of a mixture of silica gel, which has been previously loaded with a set wt% of acidified water, and polytetrafluoroethylene, PTFE, powders, a water-permeable barrier layer, and a Congo-Red-based pH indicator layer, all vacuum-sealed in a water impermeable plastic film. The value of the wt% is calculated from the ratio of the mass of acidified water added to the mass of originally dry silica gel. The high pressures associated with HPP drive the release of the acidified water from the silica gel and its subsequent transport through the water-permeable barrier layer to the pH indicator, thereby producing a striking red-to-blue colour change. The response of the HPP indicator can be tuned to different HPP conditions by varying the wt% of acidified water used to load the silica gel powder. Indicators, with 61, 63, and 65 wt% acidified water loaded silica gel, are prepared and found to require, respectively, the application of at least, 600, 400, and 300 MPa pressure for 3 min to effect a change colour. To our knowledge, this is the first reported example of a prototype HPP indicator that can be tuned to respond to the very different pressure and time conditions used in HPP to sterilise such very different products as milk, apple and orange juice, and aloe vera gel.

PFAS immobilization using in-situ application of colloidal activated carbon at a geologically complex site

<p>Due to the exceptional persistence and resistance to degradation of per- and polyfluoroalkyl substances (PFASs), novel technologies for in-situ treatment and remediation of these pollutants are urgently needed. While there is still a need for more evidence from well-documented field applications, a promising technique is the use of activated carbon (AC) sorbents that can immobilize PFASs in groundwater and thereby prevent further spreading of the contaminants.</p><p>In Arboga Sweden a small fire-fighting training area connected to aviation industry is contaminated by PFAS from aqueous film forming foams (AFFFs). This site has been characterized for PFAS contamination and hydrogeological parameters affecting the spreading of contaminants with the groundwater in a few smaller site investigations since 2016 and continuous monitoring since 2018. In November 2019 colloidal activated carbon (CAC) was injected in a pilot-scale test to study the capability of CAC to immobilize PFASs in a part of the contamination plume.</p><p>The complex geology of the site made the injection of CAC challenging and special measures had to be taken to avoid excessive preferential flow of the CAC particles even at low-pressure injection. The injection pattern was modified and CaCl<sub>2</sub> was injected downstream of the CAC injection to reduce CAC mobility and create a defined zone of CAC intercepting the PFAS plume in the groundwater, thus acting like a PFAS-immobilizing permeable barrier.</p><p>PFAS concentrations were initially reduced by 74% (for a sum of 11 PFASs) directly downstream of the CAC-barrier. However, a few months later PFAS concentrations rebounded to levels equally high or higher than before CAC injection, after which the levels have been going down again. The reasons to the rebound are likely connected to seasonal changes and fluctuations in the groundwater flow directions, causing bypass of the permeable CAC barrier. Lessons learned from applying CAC injections at this field site include the key importance of understanding the groundwater flow patterns and its temporal variability. CAC was able to produce significant reduction in PFAS concentrations (74%), but only when the PFAS plume was properly intercepted. The results illustrate the challenges with application of permeable barrier techniques particularly at geologically complex field sites. At such sites, sorbents for immobilization of PFAS plumes in groundwater should be applied in the most straightforward location where a year-round interception of the plume can be obtained.</p>

Bioactive Ether Lipids: Primordial Modulators of Cellular Signaling

The primacy of lipids as essential components of cellular membranes is conserved across taxonomic domains. In addition to this crucial role as a semi-permeable barrier, lipids are also increasingly recognized as important signaling molecules with diverse functional mechanisms ranging from cell surface receptor binding to the intracellular regulation of enzymatic cascades. In this review, we focus on ether lipids, an ancient family of lipids having ether-linked structures that chemically differ from their more prevalent acyl relatives. In particular, we examine ether lipid biosynthesis in the peroxisome of mammalian cells, the roles of selected glycerolipids and glycerophospholipids in signal transduction in both prokaryotes and eukaryotes, and finally, the potential therapeutic contributions of synthetic ether lipids to the treatment of cancer.

Pregnancy success in mice requires appropriate cannabinoid receptor signaling for primary decidua formation

With implantation, mouse stromal cells begin to transform into epithelial-like cells surrounding the implantation chamber forming an avascular zone called the primary decidual zone (PDZ). In the mouse, the PDZ forms a transient, size-dependent permeable barrier to protect the embryo from maternal circulating harmful agents. The process of decidualization is critical for pregnancy maintenance in mice and humans. Mice deficient in cannabinoid receptors, CB1 and CB2, show compromised PDZ with dysregulated angiogenic factors, resulting in the retention of blood vessels and macrophages. This phenotype is replicated in Cnr1-/- but not in Cnr2-/-mice. In vitro decidualization models suggest that Cnr1 levels substantially increase in mouse and human decidualizing stromal cells, and that neutralization of CB1 signaling suppresses decidualization and misregulates angiogenic factors. Taken together, we propose that implantation quality depends on appropriate angiogenic events driven by the integration of CB2 in endothelial cells and CB1 in decidual cells.

Who goes there? Social surveillance as a response to intergroup conflict in a primitive termite

Intergroup conflict has been suggested as a major force shaping the evolution of social behaviour in animal groups. A long-standing hypothesis is that groups at risk of attack by rivals should become more socially cohesive, to increase resilience or protect against future attack. However, it is usually unclear how cohesive behaviours (such as grooming or social contacts) function in intergroup conflict. We performed an experiment in which we exposed young colonies of the dampwood termite, Zootermopsis angusticollis , to a rival colony while preventing physical combat with a permeable barrier. We measured social contacts, allogrooming and trophallaxis before, during and after exposure. Termites showed elevated rates of social contacts during exposure to a rival compared to the pre-exposure phase, but rates returned to pre-exposure levels after colonies were separated for 9 days. There was evidence of a delayed effect of conflict on worker trophallaxis. We suggest that social contacts during intergroup conflict function as a form of social surveillance, to check individual identity and assess colony resource holding potential. Intergroup conflict may increase social cohesion in both the short and the long term, improving the effectiveness of groups in competition.