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Biomedical subjects

Andrew J McWhorter

Publications and source records attributed to Andrew J McWhorter.

6 recordsLinked to original sources
PubMed2006

Investigation of voice initiation and voice offset characteristics with high-speed digital imaging.

This study involves preliminary investigation of the characteristics of the voice initiation period (VIP) and voice offset period (VOP) using high-speed digital imaging. The goals of the study were to develop a methodology to objectively analyze these periods of phonation and to explore the feasibility of studying the effects of aging on these phonation segments. Results of the analysis of the data from two female subjects, one younger and one older, with the developed methodology, demonstrated that the older subject's VIP was characterized by a slow and irregular increase in glottal area waveform (GAW) until reaching 90% of the maximum opening of the glottis at 244 frames or 122 ms. The younger subject demonstrated a sharp increase in GAW during VIP, taking only 155 frames or 77.5 ms to reach the 90% mark. Also, the older subject took a greater number of frames for the vocal fold vibration to come to a complete stop than the younger subject during the VOP; 275 frames and 150 frames respectively.

Adult↗
PubMed2005

The ATM/p53 pathway is commonly targeted for inactivation in squamous cell carcinoma of the head and neck (SCCHN) by multiple molecular mechanisms.

The ATM/p53 pathway plays a critical role in maintenance of genome integrity and can be targeted for inactivation by a number of characterized mechanisms including somatic genetic/epigenetic alterations and expression of oncogenic viral proteins. Here, we examine a panel of 24 SCCHN tumors using various molecular approaches for the presence of human papillomavirus (HPV), mutations in the p53 gene and methylation of the ATM promoter. We observed that 30% of our SCCHN samples displayed the presence of HPV and all but one was HPV type 16. All HPV E6 gene-positive tumors exhibited E6 transcript expression. We observed 21% of the tumors harbored p53 mutations and 42% of tumors displayed ATM promoter methylation. The majority of tumors (71%) were positive for at least one of these events. These findings indicate that molecular events resulting in inactivation of the ATM/p53 pathway are common in SCCHN and can arise by a number of distinct mechanisms.

Ataxia Telangiectasia Mutated Proteins↗
PubMed2005

Transoral lateral oropharyngectomy for squamous cell carcinoma of the tonsillar region: I. Technique, complications, and functional results.

OBJECTIVES: To describe the surgical technique for transoral lateral oropharyngectomy (TLO) and its safety, postoperative management, complications, and functional outcomes. DESIGN: A 20-year retrospective case series review. Mean follow-up was 10 years. All but 10 patients were followed up until the fifth postoperative year or death. SETTING: Academic, tertiary referral center. PATIENTS: A total of 191 patients who underwent TLO for selected invasive squamous cell carcinoma of the tonsil and/or tonsillar fossa. INTERVENTIONS: Ten patients had received preoperative radiation therapy. Induction chemotherapy was used in 153 patients (80.3%). An associated neck dissection was performed in 148 patients (77.5%). Postoperative radiation therapy was administered to 52 patients (28.7%). MAIN OUTCOME MEASURES: Overall survival rate, intraoperative mortality, and perioperative mortality were determined. The need for and length of nasogastric tube feeding and tracheotomy were calculated. The incidence of significant postoperative surgical and medical complications was recorded. RESULTS: No intraoperative mortality occurred, but 5 patients (2.6%) died in the immediate postoperative period, 3 from medical complications and 2 from unknown causes. In this series, the internal carotid artery was never injured, and no cutaneous-oropharyngeal fistulas were apparent. The incidence of significant surgical complications from the oropharynx was 6.3%. Nasopharyngeal reflux and severe rhinolalia were the most common complications, occurring in 9 patients. Increasing tobacco use was statistically correlated with an increase in postoperative pneumonia from aspiration (P = .05) but no surgical complications. Seven patients (3.7%) had a temporary tracheotomy for a mean of 5 days. One hundred twelve patients (58.6%) had a nasogastric tube inserted for a mean of 6 days. No patients had a permanent gastrostomy or tracheotomy tube. The mean duration of hospitalization was 9 days. The duration of hospitalization was statistically correlated with the need for nasogastric tube placement and its duration (P<.001) or tracheotomy (P<.001). CONCLUSIONS: From a functional standpoint, the TLO is a safe surgical approach for treating selected carcinoma of the tonsillar fossa. It is a reliable technique that should be considered for treatment of appropriate squamous cell carcinoma of the tonsil.

Adult↗
PubMed2003

Tracheotomy: timing and techniques.

PURPOSE OF REVIEW: Until the past 40 years, the timing of tracheotomy was of little concern. It was an emergency procedure developed for the relief of airway obstruction. Following the development of positive pressure ventilation, tracheotomy became an elective procedure. Today, the optimal time for tracheotomy is a subject of dispute and continued investigation. As this operation has become one of the most commonly performed procedures in the intensive care unit, nonoperative dilational methods have gained acceptability. The purpose of this review is to analyze the recent literature and draw insight into the timing and technique of the current state of tracheotomy. RECENT FINDINGS: Individualized assessment of patients should guide the timing of tracheotomy, with a preference toward early tracheotomy. Percutaneous dilational tracheotomy (PDT) can be performed with equivalent safety to open tracheotomy. Bedside open tracheotomy negates the cost-saving benefits of PDT. Endoscopic guidance in PDT decreases complications with needle placement and posterior tracheal wall injury. Major complications of PDT usually are associated with displacement of the tracheotomy tube. SUMMARY: Tracheotomy indications have remained unchanged, but the timing of the procedure has advanced to individualized assessment with a predilection for earlier tracheotomy. The traditional operative technique is a much safer procedure today. Percutaneous dilational tracheotomy has become an acceptable alternative with proper patient selection. A multidisciplinary team with a surgeon provides the best care for the patient undergoing percutaneous tracheotomy.

Humans↗