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The Emerging Role of Exosome Nanoparticles in Regenerative Medicine
Published in Harishkumar Madhyastha, Durgesh Nandini Chauhan, Nanopharmaceuticals in Regenerative Medicine, 2022
Zahra Sadat Hashemi, Mahlegha Ghavami, Saeed Khalili, Seyed Morteza Naghib
A pre-processing step is often necessary for biological sample preparation, to be visible under EM (Mehdizadeh et al. 2014). These sample preparations consisted of some treatments like dehydration (organic solvents are replaced by water), chemical fixation (chemical crosslinking of lipids with osmium tetroxide and proteins with formaldehyde or glutaraldehyde), and cryofixation (called cryogenic electron microscopy (cryo-EM)). Sometimes electron beam may damage the sample to overcome this problem. The cryo-EM could be applied for EVs analysis. It is the method used to study heterogeneous shapes of exosomes close to their native state. The specimen rapidly (in milliseconds) becomes cooled and frozen to cryogenic temperatures (usually at the temperature of liquid nitrogen), which are enough to form icecrystals. The water molecules are not regularly arranged in a hexagonal lattice and a vitreous ice is formed, which is an amorphous solid form of water (Tivol et al. 2008; Debenedetti 2003).
Cellular Injury Associated with Organ Cryopreservation: Chemical Toxicity and Cooling Injury
Published in John J. Lemasters, Constance Oliver, Cell Biology of Trauma, 2020
Gregory M. Fahy, Carla da Mouta, Latchezar Tsonev, Bijan S. Khirabadi, Patrick Mehl, Harold T. Meryman
Organ cryopreservation is a frontier discipline both in cryobiology and in pathology. Cryopreservation refers to preservation at cryogenic temperatures, which for our present purposes will be considered any temperature below about -100°C. For organ cryopreservation to succeed, it is necesary that the organ survive low-temperature exposure per se, and it appears necessary for the organ to survive exposure to certain chemical agents (known generically as cryoprotective agents [CPAs] or cryoprotectants) at concentrations so high that they preclude ice formation during cooling.1 Aqueous solutions that do not freeze upon cooling eventually revert to the glassy state, a glass being a liquid the molecular motions of which have been largely arrested.2 This conversion to the glassy state is referred to as vitrification, and organ cryopreservation in the absence of ice is referred to as organ vitrification.
Organization and Management of a Laser Safety Program
Published in Kenneth L. Miller, Handbook of Management of Radiation Protection Programs, 2020
Cryogenic liquids used as coolants can cause skin burns, eye irritations, and can interact chemically with metallic objects such as jewelry. Insulated gloves and eye protection shall be worn when handling these liquids. Dyes used as the laser active medium may be toxic and, in some cases, carcinogenic. Although the concentration of dye in the laser dye solution is small, the solvents typically have flammable and toxic properties. For this reason, proper precautions must be taken by individuals who work on dye lasers, who replace the dye in the lasers, and who prepare the solutions. The user is not at risk unless the container holding the dye solution should leak dye from system containment.
The new normal: a UK fertility clinic experience of universal RT-PCR SARS-CoV-2 testing
Published in Human Fertility, 2023
Ektoras X. Georgiou, Victoria Ryder, Julia Paget, Richard Banks, Ying C. Cheong
The CFC testing plan was introduced on 12th May 2020 (Figure 1). Specifically, an initial RT-PCR swab was performed between 2 and 7 days prior to treatment initiation, with treatment for any patients with a positive swab being postponed. Patients with a negative swab embarking on treatment were asked to self-isolate and in cases where this was not possible, weekly RT-PCR testing was required. Irrespective of whether patients were undergoing weekly testing, all patients were asked to fill in a triage screening questionnaire (Supplementary online material) at each clinic visit. In cases where the questionnaire indicated a possible COVID-19 infection risk, a repeat swab was performed. Any positive cases were discussed at the daily multi-disciplinary meeting including the medical, embryology and nursing teams and treatment cycles were postponed. Where a positive case arose mid-stimulation, the cycle would be cancelled to allow the patient, and their partner if applicable, to self-isolate as per government guidance, unless the patient was undergoing urgent fertility preservation pre-cancer treatment. Where a positive case arose post oocyte retrieval and prior to embryo transfer, a freeze all would be performed using a designated cryogenic storage dewar. Patients developing COVID-19 infection during treatment were invited to proceed with a new cycle after clinical recovery, completion of the necessary isolation period and a negative RT-PCR swab. Contingency plans were made in case of lack of sufficient RT-PCR testing capability, although these were not deployed.
Photoprotective effect of solid lipid nanoparticles of rutin against UVB radiation damage on skin biopsies and tissue-engineered skin
Published in Journal of Microencapsulation, 2022
Rodrigo Molina Martins, Silvia de Siqueira Martins, Gustavo Luis Ferreira Barbosa, Maria José Vieira Fonseca, Patrick J. Rochette, Véronique J. Moulin, Luis Alexandre Pedro de Freitas
Four hours after irradiation skin samples were frozen and underwent cryogenic grinding using the CryoMill system (Verder Scientific, Inc., Newtown, PA, USA). Crushed samples were then dispersed in 10 mM Tris, 150 mM NaCl, 10% glycerol, and 0.25% Triton X-100 at a ratio of 1:1. Protein content was determined using the BCA Protein Assay Kit. For the lipid peroxidation assay, 100 µL of each sample was added to 100 µL of 130 mM KCl/10 mM Tris-HCl (pH 7.4) buffer containing 10 µL of sodium citrate (200 mM) and 10 µL of ammonium iron sulphate following incubation at 37 °C for 30 min. Next, the thiobarbituric acid-reactive substance assay was carried out as previously described by Martins et al. (2020). Total metalloproteinase activity was determined using the SensoLyte 520 Generic MMP Assay Kit-Fluorimetric (AnaSpec, Fremont, CA, USA) according to the manufacturer’s protocol. The following metalloproteinase activities are detected using this kit: 1, 2, 7, 8, 9, 10, 12, 13, and 14.
Spray freeze-drying for inhalation application: process and formulation variables
Published in Pharmaceutical Development and Technology, 2022
Mostafa Rostamnezhad, Hossein Jafari, Farzad Moradikhah, Sara Bahrainian, Homa Faghihi, Reza Khalvati, Reza Bafkary, Alireza Vatanara
Unlike the SFV/L, the nozzle in the SFL is located in the lower parts, directly in contact with the liquid (Figure 1). This liquid can be cryogenic. SFL can be conducted at atmospheric pressure with liquid nitrogen, hydrofluoroether, pentane, and argon. Also, it is applicable in the pressurized systems of liquid carbon dioxide, propane, and/or ethane. Droplets are frozen immediately after formation. The cryogenic agents may be stirred to prevent particle aggregation. Then, the frozen droplets are freeze-dried to produce a dry powder with an elegant flow. In the SFL, a liquid–liquid collision occurs between the atomized droplets ejected from the nozzle and the cryogenic liquid. The higher density and viscosity of liquids compared to gases cause the necessity for more vigorous atomization leading to create smaller droplets accordingly (Hu et al. 2002). The smaller droplets increase the specific surface area of the resultant particles and the heat transfer (Engstrom et al. 2007). Furthermore, supersaturation generates a high rate of nucleation from the dissolved components. Rapid nucleation, followed by a limited core growth, results in very small particles (Hu et al. 2002). The high surface area and minimum drug destruction have made this method suitable for preparing the dosage forms (Yu et al. 2004).