A Mathematical Model for Transport in Poroelastic Materials with Variable Volume: Derivation, Lie Symmetry Analysis and Examples. Part 2

The model for perfused tissue undergoing deformation taking into account the local exchange between tissue and blood and lymphatic systems is presented. The Lie symmetry analysis in order to identify its symmetry properties is applied. Several families of steady-state solutions in closed formulae are derived. An analysis of the impact of the parameter values and boundary conditions on the distribution of hydrostatic pressure, osmotic agent concentration and deformation of perfused tissue is provided applying the solutions obtained in examples describing real-world processes.

Impact of Using Alternative Sweetener as Osmotic Agent on Mass Transfer, Colour and Texture Properties During Dip Dehydration of Apple Slice

Previous study has explored dip dehydration as a novel variant of osmotic dehydration to reduce solid gain, which is the main problem of osmotic dehydration. However, this dehydration process commonly uses sucrose solution as osmotic agent which might contribute to the increase in glycaemic index and can also be linked to different diseases such as diabetes and obesity. Therefore, this study aims to investigate the effect of using alternative sweeteners as an osmotic agent on mass transfer, colour, and texture profiles during dip dehydration of apple slices. Three alternative sweeteners, i.e., erythritol, sorbitol and xylitol with 30% (w/v) concentration were used in this study. Apple slices with 1.5 mm thickness and diameter of 55 mm were dipped multiple time in the same concentrated solution every 40 minutes until 200 minutes before samples were analysed. Findings showed that different type of sweetener affect water loss and solid gain. Xylitol and sorbitol gave highest water loss about 36% and 40%, respectively. Lowest total colour different with fresh apple has been observed in sample treated with xylitol. As for texture, there is no remarkable effect of using alternative sweetener as osmotic agent at all processing times. Overall, the best alternative sweetener for sucrose is xylitol considering the mass transfer and quality of apple slices.

Structural investigation and application of Tween 80-choline chloride self-assemblies as osmotic agent for water desalination

Forward osmosis (FO) process has been extensively considered as a potential technology that could minimize the problems of traditional water desalination processes. Finding an appropriate osmotic agent is an important concern in the FO process. For the first time, a nonionic surfactant-based draw solution was introduced using self-assemblies of Tween 80 and choline chloride. The addition of choline chloride to Tween 80 led to micelles formation with an average diameter of 11.03 nm. The 1H NMR spectra exhibited that all groups of Tween 80 were interacted with choline chloride by hydrogen bond and Van der Waals’ force. The influence of adding choline chloride to Tween 80 and the micellization on its osmotic activity was investigated. Despite the less activity of single components, the average water flux of 14.29 L m‒2 h‒1 was obtained using 0.15 M of Tween 80-choline chloride self-assembly as draw solution in the FO process with DI water feed solution. Moreover, various concentrations of NaCl aqueous solutions were examined as feed solution. This report proposed a possible preparation of nonionic surfactant-based draw solutions using choline chloride additive with enhanced osmotic activities that can establish an innovative field of study in water desalination by the FO process.

Three Cases of Intraoperative Acute Fluid Misdirection Syndrome during Cataract Surgery

Purpose: We report the management of three cases of intraoperative acute fluid misdirection syndrome during cataract surgery.Case summary: Cataract surgery was performed in one eye of an 82-year-old woman with pseudoexfoliation syndrome, one eye of an 80-year-old man with end-stage glaucoma, and both eyes of a 72-year-old man with pseudoexfoliation syndrome. In the first two cases, the capsular bag space decreased during cortex aspiration and after removal of the cortex, respectively. After intravenous mannitol and intake of oral acetazolamide, the intraocular lens was successfully inserted in the first two cases on the same day. In the third case, after first removing the nucleus and cortex of the right eye, the capsular bag space decreased and an intraocular lens was carefully inserted. No intraoperative complications were seen during the left eye operation. One month after the operation, the best-corrected visual acuity had improved and the intraocular pressure was within normal limits for all three cases.Conclusions: A relatively shallow chamber, pseudoexfoliation, zonular laxity, and use of high molecular weight ophthalmic viscosurgical devices may cause acute fluid misdirection syndrome during cataract surgery. Pars plana vitrectomy may be required. However, intravenous high osmotic agent treatment should be attempted first, followed by intraocular lens insertion on the same day.

MO694SWELLING OF PERITONEAL TISSUE DURING PERITONEAL DIALYSIS: COMPUTATIONAL ASSESSMENT USING POROELASTIC THEORY

Background and Aims Experimental studies and computational modeling show increased hydration of peritoneal tissue close to peritoneal surface after intraperitoneal (ip) administration of hypertonic dialysis fluid. This overhydration - due to fluid inflow from peritoneal cavity (driven by increased intraperitoneal pressure) and from blood (due to high interstitial concentration of osmotic agent diffusing from the cavity) - may lead to tissue swelling, as observed in experiments and in disturbed physiological conditions. We estimated the degree of swelling using linear poroelastic theory with fluid and solute transport parameters obtained from clinical studies. Method The spatially distributed model of peritoneal transport was extended by equations for tissue deformation and stress derived from linear poroelastic theory. The model describes also fluid and osmotic agent flows across tissue and capillary wall. We assumed that transport and deformation occur across a layer of tissue with initial intact width L0 and deformed width L; the deformation is described as the ratio L/L0. Transport parameters are assumed as average values estimated for intact tissue by Stachowska-Pietka (2019). As tissue stiffness (Lame coefficient) for muscle is not known, we examined stiffness ranging from 110 mmHg (connective tissue; interstitium) to 700 mmHg (solid tumor). We assumed that for initial periods of peritoneal dialysis when osmotic pressure of dialysis fluid is high: 1) osmotic pressure gradient across the capillary wall prevails over the combined Starling forces, 2) spatial profile of osmotic agent concentration in tissue (interstitial fluid) can be approximated by exponential function with the penetration depth ΛS. The model yields an equation for L/L0 to be solved numerically, but an approximated closed formula also works well for typical dialysis conditions. Results The model predicts that swelling of peritoneal tissue depends on factors such as tissue stiffness, tissue width, solute penetration depth, and transport parameters for tissue and capillary wall, and on the forces that induce fluid transport: intraperitoneal pressure and the increment of osmolality of dialysis fluid over plasma osmolality. Examples of L/L0 yielded by the model - with use of glucose 1.36% dialysis fluid and for two levels of ip hydrostatic pressure (Pip) - are shown. In Figure, left panel, for L0 = 1 cm representing human abdominal muscle, and solute diffusional penetration ΛS=ΛD=0.055 cm, or lower, as due to diffusion against fluid flow, ΛS=ΛD/2=0.027 cm, is plotted versus the tissue stiffness; the dialysis fluid with glucose 1.36% is applied (osmolality increment of 60 mmol/L at the beginning of peritoneal dwell, Waniewski et al, 1996) and Pip is 15 mmHg. As stiffness of abdominal and bowel muscles may be expected around 300 mm Hg, swelling might be up to 15%; it decreases with lower ip hydrostatic and osmotic pressures. Hypothetical dialysis at Pip = 0 (isobaric with interstitial fluid) would reduce swelling by factor 2, see Figure, right panel. The depth of osmotic agent penetration into the tissue impacts tissue hydration and swelling, see Figure 1 for L/L0 with twice reduced ΛS. The model and its approximation by the closed formula provide practically the same outcomes for clinical peritoneal dialysis, see Figure 1, but some discrepancy between them may occur for thin tissue, as rat abdominal wall. The approximate formula for L/L0 works well if ΛS is much shorter than L0. Nevertheless, for high degree of swelling a nonlinear theory should be constructed. Conclusion In peritoneal dialysis, exposure of peritoneal tissue to hypertonic dialysis fluid at increased hydrostatic pressure contributes to overhydration and swelling (by 5-15% after fluid infusion) of the tissue. The extent by which this swelling may contribute to changes in peritoneal tissue structure and function warrants further studies.

A Review of Novel Drug Delivery Controlled Porosity Osmotic Pump Tablets Therapeutic Approach and Future Trend

The review work is comprised the enhancement of bioavailability and increase therapeutic efficacy. The porous osmotic pump tablets were designed using D‐Optimal design and numerical optimization technique was applied to find out the best formulation. Another hand an osmotic pump (OP) were designed and evaluated with the aim to deliver drug in a controlled manner. Osmotic agent and pore former was considered as independent variables. Drug release rate at 2 h, 4 h, 8 h, 12 h, T50% and release exponent (n) were taken as responses. The increase in concentration of pore former and osmotic agent after a limit, changes the release was measured. The optimized formulation follows mechanism measured. The FT‐IR and DSC studies revealed that no physicochemical interaction between excipients and drug. The influence of pH and agitation intensity on the release of drug was studied and the release mechanism was through osmosis. Stability studies revealed that optimized formulation was stable. The result of D‐ Optimal design and ANOVA studies reveals that osmotic agent and pore former have significant effect on the drug release up to 12 h. The observed independent variables were found to be very close to predicted values of most satisfactory formulation which demonstrates the feasibility. Keywords: osmotic pump, pore former, bioavailability

In vitro conservation and genetic diversity of threatened species of Melocactus (Cactaceae)

The high endemism, the natural habitat degradation, and the over-collection for ornamental purposes have led some species such as Melocactus paucispinus and M. glaucescens to be threatened with extinction. The use of in vitro conservation techniques, such as slow growth storage, promotes the preservation of genetic diversity with integrity. The goal of this study was to establish a strategy for in vitro conservation of apical segments of the cladode of M. paucispinus and M. glaucescens and evaluate the genetic diversity of individuals from in vitro germinated plants. For such purpose, different concentrations of the plant regulator ancymidol and the osmotic agent sucrose on the inhibition of the in vitro growth were tested, and the genetic diversity of M. paucispinus and M. glaucescens individuals stored in vitro was evaluated. Sucrose showed higher efficiency in the reduction of growth than ancymidol for both species. However, due to the reduction in survival percentage, the use of sucrose over 75 g L− 1 in the in vitro conservation of both species for 360 days is not recommended. In the genetic diversity analysis, 76.92% of polymorphic loci (P), expected heterozygosity (He) = 0.276 and Shannon index (S) = 0.414 were observed for M. paucispinus. For M. glaucescens, the observed values were P = 95.38%, He = 0.228 and S = 0.369. These values observed here were higher than those previously found for the natural populations of these species, which demonstrated that this in vitro collection showed genetic diversity and can be used in management and reintroduction programs of these species.