Endolaryngeal extrusion of expanded polytetrafluoroethylene implant after medialization thyroplasty

Various nonresorbable implants are currently used worldwide for medialization thyroplasty in patients with unilateral vocal cord paralysis. The Gore-Tex (expanded polytetrafluoroethylene) implant was introduced in the late 1990s. At our institution, 27 patients with unilateral laryngeal nerve paralysis had medialization thyroplasty with a Gore-Tex implant during the years 1998 to 2002. The current report documents our first case of endolaryngeal extrusion of a Gore-Tex implant.     

Partial agonist clonidine mediates alpha(2)-AR subtypes specific regulation of cAMP accumulation in adenylyl cyclase II transfected DDT1-MF2 cells

alpha2-Adrenergic receptor (alpha(2)-AR) activation in the pregnant rat myometrium at midterm potentiates beta(2)-AR stimulation of adenylyl cyclase (AC) via Gbetagamma regulation of the type II isoform of adenylyl cyclase. However, at term, alpha(2)-AR activation inhibits beta(2)-AR stimulation of AC. This phenomenon is associated with changes in alpha(2)-AR subtype expression (midterm alpha(2A/D)-AR > alpha(2B)-AR; term alpha(2B) >or =alpha(2A/D)-AR), without any change in ACII mRNA, suggesting that alpha(2A/D)- and alpha(2B)-AR differentially regulate beta(2)-cAMP production. To address this issue, we have stably expressed the same density of alpha(2A/D)- or alpha(2B)-AR with AC II in DDT1-MF2 cells. Clonidine (partial agonist) increased beta(2)-AR-stimulated cAMP production in alpha(2A/D)-AR-ACII transfectants but inhibited it in alpha(2B)-AR-ACII transfectants. In contrast, epinephrine (full agonist) enhanced beta(2)-stimulated ACII in both alpha(2A)- and alpha(2B)-ACII clonal cell lines. 4-Azidoanilido-[alpha-(32)P]GTP-labeling of activated G proteins indicated that, in alpha(2B)-AR transfectants, clonidine activated only Gi(2), whereas epinephrine, the full agonist, effectively coupled to Gi(2) and Gi(3). Thus, partial and full agonists selectively activate G proteins that lead to drug specific effects on effectors. Moreover, these data indicate that Gi(3) activation is required for potentiation of beta(2)-AR stimulation of AC by alpha(2A/D) and alpha(2B)-AR in DDT1-MF2 cells. This may reflect an issue of the amount of Gbetagamma released upon receptor activation and/or betagamma composition of Gi(3) versus Gi(2).     

Decrease of breast cancer cell invasiveness by sodium phenylacetate (NaPa) is associated with an increased expression of adhesive molecules

Sodium phenylacetate (NaPa), a non-toxic phenylalanine metabolite, has been shown to induce in vivo and in vitro cytostatic and antiproliferative effects on various cell types. In this work, we analysed the effect of NaPa on the invasiveness of breast cancer cell (MDA-MB-231, MCF-7 and MCF-7 ras). Using the highly invasive breast cancer cell line MDA-MB-231, we demonstrated that an 18-hour incubation with NaPa strongly inhibits the cell invasiveness through Matrigel (86% inhibition at 20 mM of NaPa). As cell invasiveness is greatly influenced by the expression of urokinase (u-PA) and its cell surface receptor (u-PAR) as well as the secretion of matrix metalloproteinases (MMP), we tested the effect of NaPa on these parameters. An 18-hour incubation with NaPa did not modify u-PA expression, either on MDA-MB-231 or on MCF-7 and MCF-7 ras cell lines, and induced a small u-PA decrease after 3 days of treatment of MDA-MB-321 with NaPa. In contrast, an 18 h incubation of MDA-MB-231 increased the expression of u-PAR and the secretion of MMP-9. As u-PAR is a ligand for vitronectin, a composant of the extracellular matrix, these data could explain the increased adhesion of MDA-MB-231 to vitronectin, while cell adhesivity of MCF-7 and MCF-7 ras was unmodified by NaPa treatment. NaPa induced also an increased expression of both Lymphocyte Function-Associated-1 (LFA-1) and Intercellular Adhesion Molecule-1 (ICAM-1), which was obvious from 18 hour incubation with NaPa for the MDA-MB-231 cells, but was delayed (3 days) for MCF-7 and MCF-7 ras. Only neutralizing antibodies against LFA-1 reversed the decreased invasiveness of NaPa-treated cells. Therefore we can conclude that the strong inhibition of MDA-MB-231 invasiveness is not due to a decrease in proteases involved in cell migration (u-PA and MMP) but could be related both to the modification of cell structure and an increased expression of adhesion molecules such as u-PAR and LFA-1.     

Comparison insight dual X-ray absorptiometry (DXA), histomorphometry,ash weight,and morphometric indices for bone evaluation in an animal model (the orchidectomized rat) of male osteoporosis

The mechanical properties of dentin are largely determined by the intertubular dentin matrix, which is a complex composite of type I collagen fibers and a carbonate-rich apatite mineral phase. We performed a small angle X-ray scattering (SAXS) study on fully mineralized human dentin to quantify this fiber/mineral composite architecture from the nanoscopic through continuum length scales. The SAXS results were consistent with nucleation and growth of the apatite phase within periodic gaps in the collagen fibers. These mineralized fibers were perpendicular to the dentinal tubules and parallel with the mineralization growth front. Within the plane of the mineralization front, the mineralized collagen fibers were isotropic near the pulp, but became mildly anisotropic in the mid-dentin. Analysis of the data also indicated that near the pulp the mineral crystallites were approximately needle-like, and progressed to a more plate-like shape near the dentino-enamel junction. The thickness of these crystallites, approximately 5 nm, did not vary significantly with position in the tooth. These results were considered within the context of dentinogenesis and maturation.     

Culture of gingival fibroblasts on bioabsorbable regenerative materials in vitro.

BACKGROUND: The use of membranes in guided tissue regeneration (GTR) can limit the apical migration of gingival cells and favor the establishment of new attachment by periodontal ligament fibroblasts. However, gingival recession during healing following GTR has been described as a frequent complication. The purpose of this study was to determine if gingival fibroblasts are affected by the composition of the bioabsorbable membranes used in mucogingival surgery. METHODS: Two type of bioabsorbable regenerative materials were used as cell carriers. Wistar rat gingival fibroblasts (RGF) were obtained from attached gingiva, cut into small fragments, and placed in culture dishes. When confluent, cells were detached using trypsin and identified as "first transferred cells" (P1). At the third passage (P3), cell count, trypan blue exclusion test, acid phosphatase activity, DNA synthesis, phase contrast microscopy, and scanning electron microscopy were performed. The cells were then placed in wells containing the membranes and incubated for 72 hours. RESULTS: When examined under microscopy, the control wells (without membranes) showed one cell type with the elongated appearance characteristic of fibroblasts. The wells with membranes showed an altered cell morphology with a high proportion of cell fragments regardless of the type of membrane used. CONCLUSIONS: These results suggest that cell carrier membranes could affect RGF morphology and thus alter gingival tissue healing following GTR.     

Interactions between a macrophage cell line (J774A1) and surface-modified poly (D,L-lactide) nanocapsules bearing poly(ethylene glycol)

The interactions of naked and surface-modified poly(D,L-lactic acid) (PLA) nanocapsules (NC), where polyethyleneglycol (PEG) was adsorbed or covalently attached, have been studied with a macrophage-like cell line. The fluorescent oil marker, DiD, was successfully encapsulated in NCs in order to follow their interactions with cells. The cell-associated fluorescence obtained with PEG-PLA NC was about 3- to 13-fold lower than that obtained with naked-PLA NC. The effects of PEG chain length, its content as a percentage of total polymer and NC concentration in the culture medium were evaluated. PEG-PLA NC showed dramatically reduced fluorescence association with cells during an 18 h incubation compared with naked-PLA NC, showing that covalent attachment of PEG is important for the persistence of low uptake. The best results in reducing cell-associated fluorescence were obtained with a surface-modified PEG-PLA NC bearing a chain with 20000 MW. Increasing the percentage of PEG produced a reduction in marker association for a given PEG chain length. Moreover, when the PEG-containing poloxamer was simply adsorbed, marker association was dependent on the extent of dilution and the type of serum in the culture medium. Serum proteins, especially immunoglobulins, increased cell-associated fluorescence for PEG-adsorbed NC, but had very little effect on PEG-PLA NC. Marker association was only partially inhibited in the presence of cytochalasin B. The mechanisms of cell-NC interaction depended on the characteristics of the NC surface in each formulation. When the NC was physically separated from cells no diffusion of fluorescent marker in aqueous medium occurred. Nevertheless, collision-mediated transfer of DiD from NC to J774 cells was a non-negligible route of marker transfer, mainly for naked NC. However, this collision-mediated transfer was reduced for the PEG-PLA NC probably due to the restricted contact between NC and cells afforded by PEG steric hindrance at the surface.