Cross-linked hydrogel and polyester resorbable ventilation tubes in a Chinchilla model.

OBJECTIVES/HYPOTHESIS: To determine the resorption rate and biocompatibility characteristics of novel cross-linked hydrogel ventilation tubes and varied formulations of polyester ventilation tubes in a Chinchilla model. STUDY DESIGN: Animal Study. METHODS: Three cross-linked glycosaminoglycan hydrogel ventilation tubes fabricated by cross-linking thiol-modified chondroitin sulfate or thiol-modified carboxymethylated hyaluronic acid, four different polyester ventilation tubes (poly L-lactide [PLA], 50/50 poly D,L-lactide-co-glycolide [PLGA], and silver-impregnated versions of PLA and PLGA tubes) were placed into the tympanic membranes of chinchillas. Commercially available fluoroplastic ventilation tubes were placed in the contralateral ear of each animal to serve as a control. Integrity of the tubes was assessed by weekly otoscopy. Biocompatibility was assessed by auditory brainstem response, by otoscopic and histologic examination of the tympanic membrane at the tube site. RESULTS: The hydrogel tubes had very short resorption times that expanded and enlarged the myringotomy site. PLGA and silver-coated PLGA tubes maintained their integrity in the tympanic membrane for similar durations of 18.9 ± 6.4 days and 21.0 ± 6.0 days, respectively. The silver-coated PLGA tubes had lower neutrophil and fibrosis scores than PLGA tubes. PLA tubes demonstrated equivalent findings to commercially available nonresorbable tubes with respect to otoscopic findings, auditory brainstem response thresholds, and histologic inflammatory scores. CONCLUSIONS: Resorbable polyester pressure equalization tubes demonstrate predictable resorption behavior and similar biocompatibility characteristics when compared with nonresorbable tubes. Silver modification may confer some stability to PLGA tubes. Hydrogel tubes have very short resorption times, tend to enlarge the myringotomy site, and show greater inflammatory changes.

Calcium hydroxyapatite fillers.

Calcium hydroxyapatite fillers have unique advantages over other fillers in regards to duration of action and volume of product required for augmentation, especially in the midface and lower face. In this article, we describe our experience with calcium hydroxyapatite fillers and compare them with other available filler products.

Current chemical peels and other resurfacing techniques.

The currently available methods for resurfacing will be addressed in this article, which has been divided into three areas of focus: chemical peels, lasers, and dermabrasion. Emphasis will be placed on chemical peels, a technique with a long history that provides a very reliable method of resurfacing and that every facial plastic surgeon should be familiar with.

Development of an animal model for wound healing in chronic rhinosinusitis.

OBJECTIVE: To develop a model for sinonasal wounding and evaluation during healing in mice with chronic eosinophilic inflammation. DESIGN: Exploratory controlled study in which chronic eosinophilic nasal and sinus inflammation was established in mice followed by wounding of the sinonasal cavity. Histologic features and gene expression were then studied. SETTING: University of Utah Center for Comparative Medicine. SUBJECTS: Chronic eosinophilic inflammation was established in mice. They were then wounded and humanely killed at days 3, 7, and 14 after wounding. MAIN OUTCOME MEASURES: Inflammation was assayed by light microscopic examination. Polymerase chain reaction analysis of transforming growth factor-beta1b, insulinlike growth factor (IGF)-1, matrix metalloproteinase (MMP)-7, MMP-9, tissue inhibitor of metalloproteinase 1 (TIMP-1), and prostaglandin E receptor EP4 expression was performed as well. Uninflamed mice were wounded and examined using the same protocol. RESULTS: Chronically inflamed mice showed higher histologic inflammatory scores before and after wounding. Expression of IGF-1, TIMP-1, and MMP-9 was also higher prior to wounding and during healing. Continued stimulation appears necessary for the chronic eosinophilic inflammation to persist. CONCLUSIONS: We successfully constructed a model in which wound healing in a setting of chronic eosinophilic inflammation can be studied. In this exploratory pilot, we demonstrated the feasibility of reproducibly wounding the sinonasal cavity of chronically inflamed mice and examining histologic and gene expression effects of the inflammatory response after wounding.

Validation of the cell cycle G(2) delay assay in assessing ionizing radiation sensitivity and breast cancer risk.

Genetic variations in cell cycle checkpoints and DNA repair genes are associated with prolonged cell cycle G(2) delay following ionizing radiation (IR) treatment and breast cancer risk. However, different studies reported conflicting results examining the association between post-IR cell cycle delay and breast cancer risk utilizing four different parameters: cell cycle G(2) delay index, %G(2)-M, G(2)/G(0)-G(1), and (G(2)/G(0)-G(1))/S. Therefore, we evaluated whether different parameters may influence study results using a data set from 118 breast cancer cases and 225 controls as well as lymphoblastoid and breast cancer cell lines with different genetic defects. Our results suggest that cell cycle G(2) delay index may serve as the best parameter in assessing breast cancer risk, genetic regulation of IR-sensitivity, and mutations of ataxia telangiectasia mutated (ATM) and TP53. Cell cycle delay in 21 lymphoblastoid cell lines derived from BRCA1 mutation carriers was not different from that in controls. We also showed that IR-induced DNA-damage signaling, as measured by phosphorylation of H2AX on serine 139 (γ-H2AX) was inversely associated with cell cycle G(2) delay index. In summary, the cellular responses to IR are extremely complex; mutations or genetic variations in DNA damage signaling, cell cycle checkpoints, and DNA repair contribute to cell cycle G(2) delay and breast cancer risk. The cell cycle G(2) delay assay characterized in this study may help identify subpopulations with elevated risk of breast cancer or susceptibility to adverse effects in normal tissue following radiotherapy.

Laryngopharyngeal abnormalities in hospitalized patients with dysphagia.

OBJECTIVES: To determine the prevalence of laryngopharyngeal (LP) abnormalities in hospitalized patients with dysphagia referred for flexible endoscopic evaluation of swallowing (FEES). STUDY DESIGN: Retrospective, blinded review by two otolaryngologists of 100 consecutive FEES studies performed and video-recorded by a speech-language pathologist (SLP). METHODS: Two otolaryngologists reviewed videos of 100 consecutive FEES studies on hospitalized patients with dysphagia for the presence of abnormal LP findings. RESULTS: Sixty-one male and 38 female patients comprised the hospital dysphagia cohort. The mean age was 62. One subject could not be evaluated because of the severity of the retained secretions, leaving 99 subjects in the cohort. Seventy-six percent had been previously intubated, with a mean intubation duration of 13 days. The overall prevalence of abnormal LP findings was 79%. Forty-five percent of the patients presented with two or more findings, which included arytenoid edema (33%), granuloma (31%), vocal fold paresis (24%), mucosal lesions (17%), vocal fold bowing (14%), diffuse edema (11%), airway stenosis (3%), and ulcer (6%). There was a significant difference in LP findings between those individuals who had or had not been intubated. CONCLUSIONS: Hospitalized patients with dysphagia are at high risk for LP abnormalities, particularly if they have been intubated, and may benefit from either 1) an initial joint examination by the SLP and otolaryngologist or 2) an otolaryngologist's review of the recorded examination conducted by the SLP. Such otolaryngology involvement could identify airway stenosis patients at an earlier stage, initiate granuloma treatment sooner, enable earlier biopsy of unexpected lesions, and allow follow-up of mucosal and neuromuscular findings that do not respond to medical management.