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Notes: The Virtual Cell is a modeling tool that allows biologists and theorists alike to specify and simulate cell-biophysical models on arbitrarily complex geometries. The framework combines an intuitive, front-end graphical user interface that runs in a web browser, sophisticated server-side numerical algorithms, a database for storage of models and simulation results, and flexible visualization capabilities. In this paper, we present an overview of the capabilities of the Virtual Cell, and, for the first time, the detailed mathematical formulation used as the basis for spatial computations. We also present summaries of two rather typical modeling projects, in order to illustrate the principal capabilities of the Virtual Cell. © 2001 American Institute of Physics.

Notes: The electric field or current density distribution around a diamond particle embedded in a metal anode during electrolytic in-processing dressing (ELID) is calculated for the two-dimensional case of a long diamond particle without protrusion and for a periodic array of such long, parallel particles. It is found that there is a field concentration at the diamond/metal boundary so that the metal dissolution rate is the largest at such boundary. For the periodic array, the average current density is independent of the diamond concentration so that the metal dissolution rate increases with increasing diamond concentration. Hence, for the same ELID effect, the current required for a high diamond concentration tool is less than that required for a low diamond concentration tool. © 2000 American Institute of Physics.

Notes: JCR:LA-cp/cp obese rats and their lean controls were evaluated as a type 2 diabetic wound healing model and the healing quality was characterized. This model of insulin resistance has been used extensively to study atherosclerosis but has not previously been used to study wound healing. Six circular excisional wounds were made on the dorsum of each rat and followed to day 21.Tracings of the wounds were made and used to assess the rate of wound closure. Planimetry showed a significantly diminished contraction of wounds in obese rats, but no significant difference in reepithelialization was observed. Collagen content was determined from the hydroxyproline content in wounded and unwounded skin. There were significantly lower levels of hydroxyproline in the wounds of obese compared to lean animals at day 21. Histology showed adipose tissue in place of dermal tissue in the JCR:LA-cp/cp rat in both unwounded tissue and in the wound at day 21. Active transforming growth factor-β1 (TGF-β1) was measured in the serum using the plasminogen activator inhibitor-1/luciferase assay and serum total TGF-β was measured using an enzyme-linked immunosorbent assay. Active TGF-β was significantly higher in the serum of obese animals compared with lean animals, while total TGF-β1 was not significantly different between the groups. Both active and total TGF-β was measured in tissue sections using the plasminogen activator inhibitor-1/luciferase assay. There was no significant difference in active TGF-β between genotypes, while obese rats had significantly higher levels of total TGF-β at day 21. These results indicate a deficiency in wound healing in obese animals characterized by decreased wound contraction, decreased collagen production, and changes in histology. The JCR:LA-cp rat develops insulin resistance, atherosclerosis and early type 2 diabetes and may be a good model for impairment of wound healing in humans with metabolic syndrome.

Notes: Abstract: Three significant advances are responsible for the recent evolution in breast reconstruction. The first of these is the introduction of the transverse rectus abdominis musculocutaneous (TRAM) flap, which made reliable autologous breast reconstruction a reality. The subsequent application of microsurgical principles to this procedure brought further refinements in terms of improved blood supply and lessened donor site morbidity. Finally, the wide acceptance of the skin-sparing mastectomy by oncologic surgeons has allowed further progress in the aesthetic possibilities that can be realized by the plastic surgeon. The authors discuss each of these factors and provide an overview of the current state of the art of autologous free tissue breast reconstruction.

Notes: Purpose This study was designed to determine the effect of opacifiers used at different ratios on the color stability of pigmented A-2186 silicone maxillofacial elastomers and to evaluate the color spectrophotometrically before and after artificial aging.Materials and Methods Sixty experimental groups of elastomers were made using various concentrations (5%, 10%, and 15%) of 4 opacifiers (Georgia kaolin powder neutral, kaolin powder calcined, Artskin white, and dry pigment titanium white) with 1 of 5 dry earth cosmetic pigment groups (no pigment [control], red, yellow ochre, burnt sienna, and a mixture of all pigments). Five specimens of each elastomer were tested, for a total of 300 specimens. All specimens were placed in an aging chamber and artificially aged by exposure to light, water spray, fluctuating temperatures, and humidity. CIE L*a*b* values were measured by spectrophotometer. The color differences (ΔE*) at various exposure energies (150, 300, and 450 kJ/m2) were subjected to 4-way analysis of variance with repeated measures (super ANOVA). Mean values were compared with Tukey–Kramer intervals calculated at the 0.05 significance level.Results The trained human eye can detect color changes (ΔE*) greater than 1.0. Adding all pigments to any of the kaolin groups did not protect silicone A-2186 from color degradation over time. Mixing red pigment in all groups at all times drastically increased ΔE* values ranging from 0.1 to 1.3 up to 16.6 to 49.6. Yellow ochre had an effect only with 10% and 15% concentrations of kaolin powder calcined, increasing the value of ΔE* to greater than 1.0. Burnt sienna had an effect only with a 15% concentration of kaolin powder calcined, increasing the value of ΔE* at 300 and 450 kJ/m2 to greater than 11.0. At the 5% concentration, kaolin powder calcined had the smallest color changes, followed by, in order, dry pigment titanium white, Artskin white, and Georgia kaolin. At the 10% concentration, Artskin white had the smallest color changes, followed by, in order, dry pigment titanium white, kaolin powder calcined, and Georgia kaolin. At the 15% concentration, Artskin white again had the smallest color changes, followed by, in order, dry pigment titanium white, Georgia kaolin, and the kaolin powder calcined. The smallest color changes in each kaolin group were at the 10% concentration for Artskin white, dry pigment titanium white, and kaolin powder calcined and at the 5% concentration for Georgia kaolin.Conclusions Mixing dry earth cosmetic pigments with opacifiers did not protect silicone A-2186 from color degradation over time, especially in the case of red pigment. The group in which pigments were mixed with 10% Artskin white had the smallest color changes over time, followed by, in order, the groups in which pigments were mixed with 10% dry pigment titanium white, 10% kaolin powder calcined, and 5% Georgia kaolin. Red pigment had a significant effect on all opacifiers, especially Georgia kaolin and kaolin powder calcined. Yellow ochre and burnt sienna had an effect only on 15% kaolin powder calcined. Among all the pigment groups tested, yellow ochre remained the most color stable over time.

Notes: A technique is presented for modifying the Blom-Singer tracheostoma valve housing to improve peristomal skin adherence for hands-free tracheoesophageal speech production following total laryngectomy. The finished product is thin, flexible, and maintains enhanced tear strength. The edges of a standard housing device for the Blom-Singer valve are trimmed to allow for better accommodation to the tissue surface without distortion. A punch biopsy instrument is used to cut uniform holes around the housing device to allow for permeation of the silicone mixture for better mechanical adherence of the materials.