Modulating a model membrane of sphingomyelin by a tricyclic antidepressant drug.

Tricyclic medicine such as amitriptyline (AMT) hydrochloride, initially developed to treat depression, is also used to treat neuropathic pain, anxiety disorder, and migraines. The mechanism of functioning of this type of drugs is ambiguous. Understanding the mechanism is important for designing new drug molecules with higher pharmacological efficiency. Hence, in the present study, biophysical approaches have been taken to shed light on their interactions with a model cellular membrane of brain sphingomyelin in the form of monolayer and multi-lamellar vesicles. The surface pressure-area isotherm infers the partitioning of a drug molecule into the lipid monolayer at the air water interface, providing a higher surface area per molecule and reducing the in-plane elasticity. Further, the surface electrostatic potential of the lipid monolayer is found to increase due to the insertion of drug molecule. The interfacial rheology revealed a reduction of the in-plane viscoelasticity of the lipid film, which, depends on the adsorption of the drug molecule onto the film. Small-angle X-ray scattering (SAXS) measurements on multilamellar vesicles (MLVs) have revealed that the AMT molecules partition into the hydrophobic core of the lipid membrane, modifying the organization of lipids in the membrane. The modified physical state of less rigid membrane and the transformed electrostatics of the membrane could influence its interaction with synaptic vesicles and neurotransmitters making higher availability of the neurotransmitters in the synaptic cleft.

Impacts of health insurance on tympanostomy tube outcomes in the pediatric population.

OBJECTIVES: Tympanostomy tube (TT) placement is a common surgical procedure for treating pediatric patients with chronic otitis media with effusion (COME) with or without recurrent acute otitis media (rAOM). Prior work suggests children from low-income families face significant disparities in access to care for rAOM or COME. The impact of these health disparities in the care of children with rAOM or COME has yet to be investigated in a state with an expanded public health insurance model. We seek to examine differences in care for patients with rAOM and COME based on insurance status and socioeconomic status (SES) in Massachusetts. METHODS: Retrospective review of 560 pediatric patients referred for TT insertion at a tertiary academic medical center between 2017 and 2019. Demographic data collected included age, ethnicity, insurance type (public, private, none) and zip code. Otologic history collected included prior AOM episodes, time to postoperative follow-up, postoperative "no-show" appointments, and number of postoperative audiograms. Multinomial logistic regression was used to isolate the effects of race and ethnicity. RESULTS: We found no major differences in preoperative outcome measures between cohorts. Postoperatively, public insurance was independently associated with decreased odds of undergoing an audiogram (OR 0.35, 95% Cl 0.16-0.76) and increased odds of "no-showing" for an appointment (OR 3.1, 95% CI 1.8-5.3). SES was not independently associated with differences in postoperative outcomes. CONCLUSION: In a state with an early expanded public health insurance model, access to care for rAOM and COME is comparable despite differences in insurance type and SES. However, enrollment in public health insurance is associated with worse measures of follow up care. Despite improvements in access to care with expanded health insurance models, retention continues to be a challenge for vulnerable populations.

Temperature-dependent anomalous viscosity of aqueous solutions of imidazolium-based ionic liquids.

Ionic liquids (ILs) are organic salts with a low melting point compared to inorganic salts. Room temperature ILs are of great importance for their widespread potential industrial applications. The viscosity of aqueous solutions of two imidazolium-based ILs, investigated in the present study, exhibits an anomalous temperature variation. Unlike conventional molecular fluids, the viscosity of 1-methyl-3-octyl imidazolium chloride [OMIM Cl] and 1-methyl-3-decyl imidazolium chloride [DMIM Cl] solutions is found to increase with temperature and then depress. The Small Angle X-ray Scattering (SAXS) data suggest that the lattice parameter of the body-centered cubic lattice formed by the spherical micelles of these ILs, and the morphology of the micelles remain intact over the measured temperature range. The molecular dynamics simulation shows the micelles to be more refined with their integrated structure on increasing the temperature. On further increase of the temperature, the structure is found to be loosened, which is corroborated by the simulation work. The ionic conductivity of these IL solutions shows a trend that is opposite to that of the viscosity. The observed anomalous nature of the viscosity is attributed to the trapped dissociated ions in the network of the micellar aggregates.

Shear-induced phase transition in the aqueous solution of an imidazolium-based ionic liquid.

An ionic liquid (IL) is a salt in the liquid state that consists of a cation and an anion, one of which possesses an organic component. Because of their non-volatile property, these solvents have a high recovery rate, and, hence, they are considered as environment-friendly green solvents. It is necessary to study the detailed physicochemical properties of these liquids for designing and processing techniques and find suitable operating conditions for IL-based systems. In the present work, the flow behavior of aqueous solutions of an imidazolium-based IL, 1-methyl-3-octylimidazolium chloride, is investigated, where the dynamic viscosity measurements indicate non-Newtonian shear thickening behavior in the solutions. Polarizing optical microscopy shows that the pristine samples are isotropic and transform into anisotropic after shear. These shear thickened liquid crystalline samples change into an isotropic phase upon heating, which is quantified by the differential scanning calorimetry. The small angle x-ray scattering study revealed that the pristine isotropic cubic phase of spherical micelles distort into non-spherical micelles. This has provided the detailed structural evolution of mesoscopic aggregates of the IL in an aqueous solution and the corresponding viscoelastic property of the solution.

Phase Diagram Study of Catanionic Surfactants Using Dissipative Particle Dynamics.

Dissipative particle dynamics (DPD) simulations has been performed to study the phase transition of a mixture of cationic and anionic surfactants in an aqueous solution as a function of the total concentration in water and the relative ratio of surfactants. The impact of the relative difference between the tail lengths of the cationic and anionic surfactants on the phase diagram has been simulated by tuning the number of DPD beads in the simulation model. This research also discusses the impact of the frequently used values of the parameters associated with the harmonic bonds among the bonded DPD beads on the obtained self-assemblies. We find remarkable differences in the resultant self-assemblies based on different choices of harmonic bond parameters. The performed simulations show an enhanced spectrum of self-assemblies with augmented tail lengths and disparate harmonic bond parameters. The obtained self-assemblies are quite unique and can potentially be used in the future for various applications. We also compare the simulation results of the vesicle structures obtained by modeling the electrostatic interaction in the simulation among the charged beads by explicitly introducing charges with a long-range interaction with those obtained by tuning the implicit electrostatic interaction without the long-range interaction. The effects of the chain length of the model and the harmonic bond parameters on the internal density of DPD beads and stress profiles within the vesicles are examined closely. These results are a significant contribution to understanding the stability of the phases and tailoring of the desired vesicles.

Tissue engineered cartilage "bioshell" protective layer for subcutaneous implants.

OBJECTIVE: One current technique to reconstruct an ear for microtia involves the use of a high density polyethylene auricular implant; however, the implant can extrude if not covered in a temporoparietal fascia flap. Theoretically, an autologous tissue engineered cartilage "bioshell" protective coating around a permanent biocompatible implant might reduce potential extrusion to avoid the flap requirement. We hypothesized that if subjected to intentional exposure, a bioshell coating over an implant would provide enhanced wound healing. METHODS: Six sheets of high density polyethylene and six sheets of 24 carat pure gold wire-mesh measuring 19 mm x 25 mm were implanted subcutaneously in an immunocompetent swine model. Half of each implant group were coated with chondrocytes (50-70 million cells/cm(3)) which were suspended in Pluronic F-127 30% hydrogel; the remaining implants without chondrocytes were used as controls. At 10 weeks post-implantation, partial implant exposure via excision of overlying skin was performed to simulate extrusion and the sites were allowed to heal secondarily. RESULTS: All (6/6) of bioshell implants achieved wound closure after exposure by the seventh post-operative day; controls achieved closure at approximately 10 days. Bioshell neocartilage was evaluated and confirmed histologically using hematoxylin and eosin and safranin O stains. Histochemically, neocartilage approximated native cartilage with 60% glycosaminoglycans content. CONCLUSION: A 'proof-of-principle' tissue engineered bioshell around subcutaneous high density polyethylene and gold implants generated an elastic neocartilage coating, elicited a low inflammatory reaction, and was associated with 30% faster wound healing.

Periosteal cell pellet culture system: a new technique for bone engineering.

To treat bone loss that is induced by disease or wounds, bone grafts are commonly used. In dentistry, guided tissue regeneration is effective in the treatment of periodontal diseases. However, bone resorption after implantation is a major problem with the bone graft and guided tissue regeneration technique. This study examines a cell pellet culture system without exogenous scaffolds for bone regeneration. First, we examined the effect of ascorbic acid on cells. Transmission electron microscopic observation revealed that cells formed a three-dimensional structure of multiple cell layers after 5 weeks of culturing in medium containing 50 microg/ ml ascorbic acid with the medium changed every 7 days. A single cell pellet was produced by centrifuging cells that were gathered from 10 tissue culture dishes. Van Gieson staining and collagen type I immunostaining showed that the pellet contained collagen fibers and cells that adhered to the collagen fibers. Several of these cell pellets were implanted subcutaneously on the backs of nude mice for 6 weeks. Histology and immunohistochemistry results indicated new bone formation, vascular invasion, and insular areas of calcification. Bone tissue was surrounded by osteoblasts. The appearance of new bone formation is similar to that seen in intramembranous ossification. The present pellet system is reliable and might solve problems of bone resorption after implantation.

Pediatric cholesteatoma: canal wall window alternative to canal wall down mastoidectomy.

OBJECTIVE: A previous pilot series described a hybrid mastoidectomy technique, canal wall window (CWW), which substituted for the canal wall down (CWD) procedure and involved slitting the posterior canal wall. The current, larger series compares the results of the CWW procedure with conventional surgical techniques. STUDY DESIGN: Retrospective analysis of 78 pediatric ears. SETTING: Academic tertiary referral center. PATIENTS: The mean patient age was 13.5 years. MAIN OUTCOME MEASURE(S): The data analyzed included ears later requiring conversion from CWW to CWD, dry/moist ear results, recidivation determined by two separate methods, and audiometric data statistically analyzed using independent-samples analysis (unpaired, two-tailed Student's t test). RESULTS: First, of 42 CWW ear procedures, 6 (14%) later required conversion to CWD. Second, dry ear results were as follows: for CWW, 94%; for CWD, 92%; and for CWU (canal wall up), 90%. Third, recidivation determined at 1 year (standard rate) was, for CWW, 19.5%; for CWD, 0%; and for CWU, 7.7%; the at-risk calculation rate was, for CWW, 27%; for CWD, 0%; and for CWU, 8.3%. The 6-year recidivation rate for all three surgical techniques was 0%. 4). The mean preoperative-to-postoperative four-tone air-bone gap change was, for CWW, from 29.7 to 26.4 dB; for CWD, from 32.9 to 39.0 dB; and for CWU, from 21.0 to 25.2 dB (postoperative CWW to CWD, p < 0.005). A postoperative air-bone gap result of 0 to 20 dB was achieved as follows: with CWW, in 13 of 36 ears; with CWD, in 2 of 14 ears; and with CWU, in 9 of 22 ears. CONCLUSION: Frequently, a CWW procedure can be substituted for a traditional CWD procedure. In the extended series, the CWW technique continued to provide hearing results similar to CWU rather than to CWD procedures in a young population who will bear the surgical outcome for many decades.

Microtia chondrocytes as a donor source for tissue-engineered cartilage.

OBJECTIVES/HYPOTHESIS: Current surgical techniques for the correction of microtia are challenging. Research in the field of tissue engineering is providing insight into chondrocyte behavior for a possible future treatment of microtia. The authors wished to evaluate the biological potential of chondrocytes isolated from microtia cartilage as compared with normal auricular cartilage as a source of tissue-engineered cartilage. STUDY DESIGN: A comparative research design to study the potential of microtia cartilage chondrocytes with normal auricular chondrocytes as a source of tissue-engineered cartilage. METHODS: Cartilage specimens from 12 pediatric patients (six normal auricular specimens and six auricular specimens with microtia) were obtained. The chondrocytes were isolated and cultured in vitro; chondrocyte number was increased by passaging. Each type of cell was implanted in nude mice to generate tissue-engineered cartilage. Eight weeks after implantation the specimens were dissected and removed. Results were compared between the normal auricular and microtia specimens in regard to cell number expansion in vitro and generation of tissue-engineered cartilage in vivo. RESULTS: An initial mean cell number of 150,000 cells in each group (normal and microtia) increased to an average cell number of 120 million cells/mL in the normal and 130 million cells in the microtia subgroups, respectively, at the end of the second passage. Histologically, both types of chondrocytes generated normal elastic cartilage. CONCLUSION: The study demonstrated the potential of cells isolated from microtia cartilage to generate tissue-engineered cartilage. Microtia cartilage represents an important additional donor source for the possible generation of a human tissue-engineered auricle.

Tissue-engineered cartilage as a graft source for laryngotracheal reconstruction: a pig model.

OBJECTIVE: To evaluate the feasibility of using tissue-engineered cartilage for laryngotracheal reconstruction in the pig model. DESIGN: Auricular cartilage was harvested from 3 young swine. The cartilage was digested, processed, and suspended and a cell culture was obtained. The cells were then suspended in 3 mL of a 30% solution of a biodegradable polymer (Pluronic F-127) (polyethylene oxide/polypropylene oxide copolymer) at a cellular concentration of 50 x 10(6) cells/mL. This suspension was then implanted subcutaneously into each pig's dorsum. Eight weeks after implantation, the cartilage was harvested with the surrounding perichondrial capsule. An anterior cartilage graft laryngotracheal reconstruction was performed. Bronchoscopy was performed at 3 postoperative weeks to demonstrate airway patency. The animals were killed at 3 months, and specimens were obtained for histological analysis. SETTING: An animal research facility. SUBJECTS: Three young Yorkshire swine. RESULTS: All 3 pigs survived to the 3-month postoperative interval with no evidence of stridor or airway distress. Interval bronchoscopy revealed a normal patent airway with a mucosalized graft. Histopathologic analysis revealed incorporation of the tissue-engineered cartilage graft in the cricoid area, which correlated with results of bronchoscopic evaluation. CONCLUSION: Tissue-engineered auricular cartilage served as a viable graft in the pig model and might be an alternative cartilage source for laryngotracheal reconstruction.

Normal features of tissue-engineered auricular cartilage by flow cytometry and histology: patient safety.

BACKGROUND: Cytokinetic abnormalities in DNA content, such as aneuploidy, haploidy, and tetraploidy, have been found to occur in human cartilaginous tumors. The high number of chondrocytes needed for tissue-engineered cartilaginous implants requires the cells to be passaged repeatedly. The theoretical risk of changes in the normal diploid state of these cells during their growth in vitro and after generation of tissue-engineered cartilage in vivo is not known. Materials and methods Auricular chondrocytes were obtained from 6 patients and cultured in vitro. Chondrocyte number was increased by repeated passaging. The passaged cells were implanted in nude mice for 8 weeks to generate tissue-engineered cartilage. Fresh control chondrocytes along with the passaged cells and cells obtained from the tissue-engineered constructs were collected and compared for DNA content by flow cytometry. RESULTS: Flow cytometry demonstrated 100% diploidy with no evidence of aneuploidy, haploidy, or tetraploidy in all groups of cells. Histology of the tissue-engineered cartilage also showed no evidence of cellular atypia. CONCLUSION: The number of human auricular chondrocytes can be increased by repeated passaging and passaged chondrocytes can be safely used for implantation to generate tissue-engineered constructs without a change in the normal diploid state of the cells. Histology of the cartilage generated showed normal features without atypia.

The Internet-current trends and future expectations among Brazilian pediatricians and otolaryngologists with a special interest in pediatric otolaryngology.

OBJECTIVE: To assess Internet use among a group of Brazilian pediatricians and otolaryngologists and to inquire about possible Web based medical resources. METHODS: Questionnaires were distributed among attendees of a 2001 Pediatric Otolaryngology meeting in Brazil. Multiple choice or yes/no questions related to the use of the Internet among physicians were presented. RESULTS: All of the 99 respondents of an estimated 900 attendees, had Internet access (high-speed 18%, conventional 77%); 52% at home, 42% in the office and 6% at both sites. Eighty-one percent of those responding regularly used the Internet for medical updating. Sharing a pediatric otolayngology medical association Web site with patients was desired by 73%; an interest in personal Web based medical information and updates was demonstrated by 97%. Five percent of respondents already had established personal practice Web sites and 54% agreed with potential benefits for improving medical practice. CONCLUSION: The potential role of electronic communication and a desire to establish a pediatric otolaryngology Web site that would maximize inclusiveness is appreciated by this group of Brazilian otolaryngologists and pediatricians.

In vitro tissue engineering to generate a human-sized auricle and nasal tip.

OBJECTIVES/HYPOTHESIS: Tissue engineering has successfully generated cartilage in a xenograft and an autograft model. However, challenges remain with both of these in vivo techniques before clinical application can be realized. We hypothesized that a human-sized cartilaginous structure could be generated completely in vitro as a complementary or an alternative technique. METHODS: Scaffolds were created in the shape of five full-sized human auricles and five nasal tip cartilaginous skeletons. Bovine shoulder chondrocytes at a concentration of 50 million cells/mL were seeded onto the scaffolds and were grown for 12 weeks in vitro. Two of the auricular scaffolds had internal support provided by soft acrylic sheets and were later implanted into nude rats. RESULTS: All of the scaffolds maintained shape and size through 12 weeks of in vitro culture. On gross examination the scaffolds were progressively replaced by cartilage, which was confirmed by histological and biochemical analysis. The auricular scaffolds with the acrylic internal support had the most natural rigidity, which was observed by gentle palpation. The nasal scaffolds maintained excellent definition even without internal support. CONCLUSION: An adult human-sized auricle and nasal tip cartilaginous structure can be grown entirely in vitro using principles of tissue engineering.