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Soft Tissue Management
Published in Jeff Garner, Dominic Slade, Manual of Complex Abdominal Wall Reconstruction, 2020
When the entire wound has granulated and the wound exudate has resolved it is possible to apply a split-thickness skin graft to the wound which will simplify the subsequent wound management. For success the skin graft must pass through four stages: the graft must first adhere to the bed by a process of fibrin adhesion so the biofilm must be scraped off the bed of the wound and the wound irrigated prior to grafting. Second, plasmatic imbibition occurs when the graft absorbs nutrients from the wound bed by diffusion allowing the graft to survive until its blood supply is established. The blood supply to the graft is thought to be re-established by two processes, inosculation and neo-revascularisation (vessels growing into the graft from the bed) – both processes occur but the proportion of each is hard to establish; it is clear that the graft establishes a blood flow within 2–4 days of grafting which is too rapid a process for neo-revascularisation to have occurred. The graft must then mature until it is robust enough to resist the shearing force placed upon it.
General Surgery
Published in Tjun Tang, Elizabeth O'Riordan, Stewart Walsh, Cracking the Intercollegiate General Surgery FRCS Viva, 2020
Rebecca Fish, Aisling Hogan, Aoife Lowery, Frank McDermott, Chelliah R Selvasekar, Choon Sheong Seow, Vishal G Shelat, Paul Sutton, Yew-Wei Tan, Thomas Tsang
Skin grafts undergo a unique healing process, with sequential, overlapping phases: Within the first few minutes, there is a period of fibrin deposition that causes the skin graft to adhere to the recipient site.Over the first couple of days, plasma imbibition occurs, where nutrients pass directly from the recipient bed into the graft.Next there is a phase of inosculation and revascularisation where blood vessels in the graft connect with those in the bed and new blood vessels also grow into the graft.Thereafter, graft maturation occurs and this phase can last weeks to months.
Photomodulation of Protonema Development
Published in R. N. Chopra, Satish C. Bhatla, Bryophyte Development: Physiology and Biochemistry, 2019
A remarkable fact shown by bryophytes as well as ferns is that a prolonged preswelling of the spores in darkness increases their sensitivity to light.18,20,23-25 Thus, much shorter irradiation times are required to give a certain response if spores are pretreated in this way. The initial swelling phase, therefore, has been related to some activation processes which control the sensitivity for light. Cove et al.17 reported strong evidence for a specific factor which is only operational with Pfr. In fern spores Tomizawa et al.26 measured an increase in the phytochrome content during the imbibition period, parallel to an increase in sensitivity to light. This effect has been related to a mobilization of stored phytochrome27 as well as to de novo synthesis.28 These findings underline some of the physiological conditions that up to now have been covered by terms like “maturity” or “ripeness”. In any case, the responsiveness of spores to light depends strictly on their pretreatment in darkness,24-25 and much attention should be paid to this fact in quantitative studies on light action.
Utilization of Perifascial Loose Areolar Tissue Grafting as an Autologous Dermal Substitute in Extremity Burns
Published in Journal of Investigative Surgery, 2023
Burak Özkan, Burak Ergün Tatar, Abbas Albayati, Cagri Ahmet Uysal
In the literature, successful results have been reported in chronic ischemic ulcers or fistulas [4, 14]. In these studies, PAT grafts were used as allogenic dermal substitutes to provide a basal layer for skin grafting. The mechanism of PAT engraftment was later demonstrated in histopathological tissue specimens. A previous study found that fibroadipose PAT is surrounded by granulation tissue, which is a supportive finding for the phenomenon of graft survival [6]. Hayashi et al. revealed a well-organized collagen deposition and endothelial cell infiltration around PAT graft-based vessels. These findings support the mechanisms underlying revascularization and rapid intake of PAT grafts [15]. The authors of a recent experimental study suggested that the rapid intake of PAT grafts may be attributed to the presence of stem cells [16]. Another hypothesis is that skin graft intake is attributed to the texture of the PAT graft, which allows for easy nutrient diffusion in the imbibition phase [16].
Preparation and characterization of aqueous vitamin E/Soluplus® dispersions for film coating applications
Published in Drug Development and Industrial Pharmacy, 2021
Ahmad Salawi, Jafrin Jobayer Sonju, Mohammad M. Kamal, Ahmed Abu-Fayyad, Turki Al Hagbani, Sami Nazzal
The relatively fast dissolution of the granules was expected. Since Soluplus® is hygroscopic, water readily absorbs into the coating layer when the dosage form comes into contact with the buffer medium. Consequently, water imbibition leads to the dissolution of the coating polymer. This was confirmed by the data that were generated from the contact angle study that demonstrated the hydrophilic nature of the vitamin E/Soluplus® films despite the presence of the hydrophobic vitamin E in the film. While the presence of vitamin E in the coating material did not seem to hinder dissolution, it might be a contributing factor to the delay in drug release. The observed delay in acetaminophen release could also be attributed to the decrease in the diffusion pathways for water and drug with increasing coating levels. Furthermore, it is possible that PVA (Polyvinyl alcohol) in Soluplus®, which is co-grafted with PEG (polyethylene glycol) imparts an internal lipophilic character to the films, thus causing a relatively slow film dissolution with a consequent delay in drug release from the granules.
Zero-order release and bioavailability enhancement of poorly water soluble Vinpocetine from self-nanoemulsifying osmotic pump tablet
Published in Pharmaceutical Development and Technology, 2018
Sally A. El-Zahaby, Mohamed H. H. AbouGhaly, Ghada A. Abdelbary, Omaima N. El-Gazayerly
All CA coated tablets followed Higuchi model (Table 2). This could be explained based on the asymmetric membrane nature used in the study. The produced porous membrane upon contact with the dissolution media makes the drug diffusion through the created pores the predominant pathway. Similarly, Bi et al. (2007) concluded that the drug release from the porous osmotic systems of theophylline is influenced by micro-environmental osmotic pressure. This pressure is produced by the osmotic agents’ dissolution in the water permeating through the membrane and the diffusion through the pores produced by the pore formers. According to Table 2, 6 out of the 18 formulae showed zero-order release kinetics. This suggests that the rate of water imbibition across the coating membrane was perfectly controlled so that a saturated solution of sodium chloride in the tablet core was maintained. This would lead to a constant osmotic pressure gradient between the tablet core and the external environment throughout the release tests durations (Abd-Elbary et al. 2011). The highest R2 value (0.998) was corresponding to the twin drilled tablets coated by 2% Opadry® CA but those tablets released the whole VNP contents (98.793%) in 8 h. On the other hand, tablets coated by 1.5% Opadry® CA and having a single drill had R2 equal to 0.993 and VNP release was continued until 24 h (data not shown) which matched the aim of formulating once daily controlled release formulation. Based on these results, single drilled tablets coated by 1.5% Opadry® CA was selected as the optimum VNP SNEOPT formulation.