Occlusion vs. Contact Dermatitis *
Robert N. Phalen, Howard I. Maibach in Protective Gloves for Occupational Use, 2023
Bock et al.43 evaluated the impact of semipermeable gloves on barrier recovery after standardized irritation with SLS. Twenty-five healthy volunteers were exposed to 1% SLS for 24 h on 4 test areas on normal skin on the upper back. Each test area was covered with semipermeable membranes (Goretex, Sympatex) and an occlusive membrane (Meditrate Vinyl), and one test area was left uncovered as control, respectively. Barrier repair on each test area was measured by TEWL and erythema. Results showed that areas covered with semipermeable membrane had enhanced barrier recovery and reduced inflammatory response compared to occluded areas and control. TEWL in areas covered with semipermeable membranes were significantly lower than in occluded areas and uncovered areas. This indicates that a semipermeable membrane can aid with barrier recovery rates by providing optimal water vapor gradient during the healing process.
Introduction: Background Material
Nassir H. Sabah in Neuromuscular Fundamentals, 2020
It is convenient to invoke semipermeable membranes in discussing ionic equilibriums, where a semipermeable membrane is a membrane that selectively allows certain substances to pass freely through the membrane in either direction while blocking other substances.
Atoms, Elements and Compounds
David Sturgeon in Introduction to Anatomy and Physiology for Healthcare Students, 2018
Whilst all this talk of diffusion is quite interesting (and slightly gross) how does it relate to the way in which ions (and other solutes) help to ensure that water is distributed in the correct fluid compartment? Well, water also moves from a high concentration to a low concentration across a semi-permeable membrane. The term ‘semi-permeable membrane’ simply refers to a thin barrier that separates the water with few solutes dissolved in it, from the water with a higher concentration of solutes dissolved in it. Think of a teabag (it is permeable to water but the tea cannot escape). Imagine that we have two small reservoirs of tap water divided by a semi-permeable membrane. On the left side, we add a table spoon of salt (NaCl). We already know what will happen to this ionic compound when dissolved in water: the sodium chloride framework will disintegrate as the Na + and Cl– ions become surrounded by water molecules. Anyway, the water on the left side is now less concentrated than that on the right because it is no longer normal tap water. The concentration of Na+ and Cl– ions is higher on the left BUT the concentration of water is lower compared to the tap water on the right. Consequently, water will diffuse from a high concentration on the right (tap water) to a low concentration on the left (tap water + NaCl) through the semi-permeable membrane that divides them. Water will stop diffusing only when the concentration on both sides is once again equal (by which time the water level on the left will be higher than that on the right). This process of water diffusion is known as osmosis and we will refer to it again and again regarding normal body function. In short, the quantity of ions (and other solutes) dissolved in water dissolved in water will have a profound effect on the osmotic concentration (osmolality) of that solution. If the osmotic concentration is too high, then the solute will attract water (until equilibrium is achieved). If the osmotic concentration is too low, water will be lost as it is attracted elsewhere. In either case, if this occurs in the human body, it can result in fluid overload or fluid depletion which may result in severe ill-health. This is one of reasons why we are (correctly) advised to limit our salt and sugar intake since they can affect the osmolality of our blood plasma, etc.
Advances in cell-laden hydrogels for delivering therapeutics
Published in Expert Opinion on Biological Therapy, 2019
Gorka Orive, Mari Carmen Echave, José Luis Pedraz, Nasim Golafshan, Alireza Dolatshahi-Pirouz, Giovanna Paolone, Dwaine Emerich
In its most basic form, cell-laden hydrogels or bioartificial organs consist of a polymeric or synthetic membrane structure that entraps a wide range of cells releasing bioactive drugs or proteins [5,6]. The three-dimensional (3D) constructs, typically either shaped as a microcapsule or a hollow-fiber, will regulate with different efficiency the permeability and mechanical stability of the cell-based medicine [7]. The semipermeable membrane is responsible for preventing high molecular weight molecules, antibodies and other immunologic components from entering within the construct but also controls the inward/outward diffusion of critical agents for cell survival and therapeutic efficacy including nutrients, oxygen, waste agents and therapeutic protein products (Figure 1). Even though the journey from theory to practice has been demanding and challenging, recent progress in the field is creating new avenues of hope to use this approach in several unmet clinical needs ranging from diabetes to ophthalmological disorders or rare diseases.
Tissue engineering approaches and generation of insulin-producing cells to treat type 1 diabetes
Published in Journal of Drug Targeting, 2023
Mozafar Khazaei, Fatemeh Khazaei, Elham Niromand, Elham Ghanbari
IPCs, produced from diverse stem cell sources, can be engrafted in vivo. Encapsulating these cells before the implant are promising strategy for treating T1D that avoids the usage of systemic immunosuppression. To protect the graft against allogenic reactions and/or autoantibodies, immune-isolation is required [119]. Cell encapsulation inside a biocompatible semipermeable membrane is commonly used to create this state. These encapsulation devices must also meet certain requirements. The permeability of such a membrane must permit unrestricted nutrients, small molecular and oxygen exchange, as well as excellent insulin kinetics in response to blood glucose variations. Furthermore, they should prevent the passage of high molecular weight complexes such as immune cells and cytokines [66].
The Double-Lumen Irrigation-Suction Tube in The Management of Incisional Surgical Site Infection After Enterocutaneous Fistula Excisions: An Observational Study
Published in Journal of Investigative Surgery, 2021
Zheng Yao*, Weiliang Tian*, Xin Xu, Risheng Zhao, Ming Huang, Yunzhao Zhao, Xinhao Chen
Once an incisional SSI occurred, patients received antibiotics (the second-generation cephalosporin) until the infection disappeared. The incision was re-opened and the infection was revealed. Before November 2016, when an SSI was diagnosed, NPWT was immediately used for deep incisional SSI and DPC for superficial incisional SSI. In our unit, the NPWT equipment was a vacuum-assisted closure (VAC)®, abdominal wound management system (KCI, San Antonio, TX, USA).When placing the VAC, the incision was re-opened, and the infections was revealed. A foam (main component: polyurethane; VAC®; KCI, San Antonio, TX, USA) is used as a cover over the infection and was tailored according to the infected incision length. A biological semipermeable membrane was used to seal the covering. After covering the suction disk, a vacuum was applied using continuous suction from an external power source (–125 mmHg). The VAC was replaced every 3 d.
Related Knowledge Centers
- Chemical Synthesis
- Facilitated Diffusion
- Molecule
- Osmosis
- Polymer
- Passive Transport
- Biological Membrane
- Membrane
- Ion
- Solution