Biomedical subjects
Publications and source records attributed to Brendan C Stack.
Primary hyperparathyroidism (HPT) has catabolic effects on cortical bone and anabolic effects on cancellous bone with overall deleterious effects on skeleton. Primary HPT is associated with increased fracture risk both at the cancellous bone-enriched spine and the cortical bone-enriched distal one third of the radius. This risk is reversed by parathyroidectomy.
This article presents the authors' technique of minimally invasive radio guided parathyroidectomy (MIRP) with intra-operative use of the hand-held gamma probe for primary HPT caused by a solitary adenoma. It points out how this approach varies from that of others who perform MIRP. It also illustrates ways to troubleshoot common problems with the technique in inexperienced hands. The goal is to present an understandable and systematic approach to MIRP for surgeons who do not currently use this technique. This article is not intended to replace formalized training, which is essential to master the technique.
Parathyroid carcinoma is a relatively rare tumor that is prone to recurrence and poor loco-regional control. This article discusses the epidemiology, presentation, operative findings, pathology,management, genetics, outcome, and other aspects of parathyroid carcinoma.
This article presents a cost-effectiveness analysis to determine whether preoperative imaging with Tc99m-sestamibi for detection and treatment of solitary adenomas associated with primary hyperparathyroidism is cost-effective compared with routine bilateral neck exploration.
Calciphylaxis is a condition with a generally poor prognosis about which relatively little is known. Possible improvement in prognosis is noted if the diagnosis can be made early to avoid progression of soft tissue lesions and resulting complications. The mainstays of therapy are wound care and therapy aimed at controlling infection and the progression of disease. Parathyroidectomy seems to benefit some patients, but controversy remains as to the extent of overall patient benefit and scenarios for its appropriate use.
OBJECTIVE: A new class of carboxylic acids has tumoricidal activity for head and neck squamous cell cancer (HNSCC). Fusaric acid (FA) can chelate divalent cations, especially zinc, and inactivate zinc finger proteins involved in DNA repair and protein synthesis. METHODS: 2 squamous carcinoma lines were utilized for in vitro and in vivo portions of this study. Cell counting and flow cytometry were used to analyze cells in culture in treatment and control groups over 96 hours. HNSCC subcutaneous implants were created in treatment and control groups of BALB-c nude mice (N = 30). RESULTS: In vitro studies demonstrated significant changes in cell numbers and cell cycle. In vivo studies of daily intralesional therapy for 1 month also showed reduced onset of growth and overall growth compared to controls. CONCLUSION: FA appears to have a tumoristatic/tumoricidal effect on HNSCC. Further nude mice studies are needed to optimize dosing and administration regimens for FA in anticipation of clinical trials.
Opioid growth factor (OGF), [Met5]-enkephalin, interacts with the OGF receptor (OGFr) to inhibit the growth of human squamous cell carcinoma of the head and neck (SCCHN) in vitro. Administration of OGF by daily intraperitoneal injection (i.p.) to animals with xenografts of CAL-27, a poorly differentiated SCCHN, is known to repress tumorigenic events. In this study, the ubiquity of OGF action on SCCHN was investigated by examination of OGF activity on SCC-1 tumors; this human cell line is well-differentiated and highly invasive. Mice receiving daily i.p. injections (10 mg/kg) of OGF had more than a 3-day delay in tumor appearance, and decreases in tumor volume ranging from 51 to 64% in comparison to controls throughout the experimental period. Receptor binding analysis for OGFr showed that binding capacity (Bmax) was 2.2-fold greater than control values, but binding affinity (Kd) was comparable. Plasma OGF levels did not vary between OGF and control groups. Mice receiving OGF by continuous infusion using minipumps, or by daily intratumoral injection, had characteristics of tumorigenicity similar to their corresponding control animals, although the OGF levels in mice receiving the OGF by minipump were elevated 18-fold greater than the control group. These data indicate that: i) the inhibitory action of OGF may be ubiquitous for SCCHN, ii) OGF treatment alters the characteristics of the OGF receptor but not of plasma OGF levels, and iii) the magnitude of effects of OGF on SCCHN is dependent on the route of administration.
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Adenoid cystic carcinoma is a fairly uncommon salivary neoplasm of the head and neck. These lesions often progress insidiously, and they have a propensity for early perineural spread and bony invasion. Distant metastasis to the lungs is fairly common and is usually fatal. We report a rare case of adenoid cystic carcinoma in a patient who on initial evaluation had widespread bony metastasis but no pulmonary involvement.
BACKGROUND: The endogenous opioid peptide, [Met(5)]-enkephalin, termed opioid growth factor (OGF), interacts with its receptor (OGFr) to play a role as a constitutively expressed inhibitory growth factor in the proliferation of epithelial cells. This study compared protein and gene expression of OGFr in surgical specimens of human squamous cell carcinoma of the head and neck (SCCHN) with normal epithelium. METHODS: Tissues from 64 patients with SCCHN and from 49 patients undergoing uvulapalatoplasty or tonsillectomy were utilized. Binding affinity and capacity were assessed by receptor binding assays and the levels of OGFr protein were determined by quantitative Western blot analysis. Immunohistochemistry assessed the presence and distribution of OGFr. Levels of OGFr mRNA were quantitated by Northern blot analysis. Protein and gene expressions of OGFr also were evaluated in the margins of SCCHN. RESULTS: Binding analyses indicated nearly ninefold fewer OGFr binding sites in tumor tissue in comparison with normal samples. The OGFr protein levels were reduced fivefold in tumor tissues relative to normal epithelium. Values of OGFr mRNA were comparable in tumors and normal epithelium. Tumor margins had intermediate levels of protein and binding, but OGFr mRNA values were similar to those of normal specimens. CONCLUSIONS: These data demonstrate that OGFr is defective in SCCHN and that translation/posttranslation of OGFr protein, but not transcriptional levels of the OGFr gene, is involved. In addition, the attenuated levels of OGFr binding capacity may serve as a marker for SCCHN. These subnormal levels of OGFr may be responsible in part for tumor progression, diminishing the interaction of OGF with OGFr that aids in stabilizing cell replication by an inhibitory mechanism. Gene therapy to reinstate OGFr and/or function could provide a useful treatment for inhibiting tumor progression.
OBJECTIVE: Amiodarone can cause thyroid dysfunction in patients with or without previous thyroid disease. With increased use from its placement in advanced cardiac life support guidelines and cardiac transplant programs, the incidence of amiodarone-induced thyrotoxicosis (AIT) will likely increase. Medical management is complex and nonuniform and frequently fails. This study investigates the role of surgery in AIT and proposes indications for surgical management. STUDY DESIGN AND SETTING: Two AIT case reports at a tertiary care institution and 31 surgical AIT cases in the world literature are reviewed. METHODS: The 2 AIT cases involved patients with cardiomyopathy and resistant arrhythmias. Despite medical therapy, both patients' conditions failed to improve. Thirty-one surgical cases of AIT in the literature are evaluated with respect to symptoms and onset, medical therapy, AIT classification, pathology, perioperative management, and complications. RESULTS: Both patients underwent total thyroidectomy without difficulty or complication, one as an overnight stay and one as an inpatient with an intraaortic balloon pump. One patient received a successful cardiac transplant and the other remains a viable candidate. In the literature, the majority (80%) of surgical cases are AIT type II (less common type) with no underlying thyroid disease. Range and duration of symptoms varied, in addition to type and duration of medical management. Almost all patients underwent total thyroidectomy, and all were successful with no mortality and minimal morbidity. CONCLUSION: AIT can develop in any patient during or after amiodarone therapy. Medical management is extremely difficult due to the absence of a proven therapeutic armamentarium, and surgery offers a safe, viable option. Surgical management should play a larger role in treatment algorithms and should be strongly considered for patients whose conditions necessitate continuation of amiodarone, or with severe symptoms resistant to medical therapy.
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Improved microsurgical technique has resulted in a high percentage of successful free tissue transfers. When a tissue transfer fails in the head and neck, however, the results are orocutaneous fistulas, carotid artery exposure, and deformity that adds morbidity, expense, and may delay adjuvant therapy. Postoperative monitoring of tissue perfusion can detect early problems in free tissue transfer that may allow for early intervention and salvage. The authors have demonstrated that reflectance photoplethysmography can detect perfusion changes in free tissue transfer within 5 minutes of a pedicle "insult" intraoperatively. Normative data for viable flaps from various donor sites have been established. The authors now report their initial experience with a newly developed reflectance photoplethysmograph based on a hand-held computer for routine clinical use. Their results are compared with a conventional surveillance protocol that included observation, bleeding to pin prick, and bedside duplex scanning of the vascular pedicle. In a series of 30 free tissue transfers (29 patients), there was one ischemic event (skin paddle loss only), which was detected by the monitor. The monitor was able to predict correctly (one flap) survival of a free tissue transfer even when duplex ultrasonic data were indicative of an absence of perfusion. Personal digital assistant-based photoplethysmography appears to be a promising device for bedside diagnosis of free tissue transfer viability or ischemia.
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Facial plastic surgeons often must make decisions with imperfect information. Statistical inference is fundamentally the practice of using data to draw conclusions about uncertain phenomena. It is important, therefore, that facial plastic surgeons engaged both in clinical practice and in research have an understanding of statistical concepts to conduct research with results that are meaningful, to assess the validity of published research, and to adopt the most effective techniques and treatments. The purpose of this article is to provide an overview of classical statistical methods that are encountered frequently in facial plastic surgery research, discuss issues of interpretation of results, and introduce an alternative paradigm for conducting statistical inference.
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Thyroid storm is a potentially life-threatening endocrinologic emergency characterized by an exacerbation of a hyperthyroid state. Several inciting factors can instigate the conversion of thyrotoxicosis to thyroid storm; trauma is one such trigger, but it is rare. Patients with thyroid storm can manifest fever, nervous system disorders, gastrointestinal or hepatic dysfunction (e.g., nausea, vomiting, diarrhea, and/or jaundice), and arrhythmia and other cardiovascular abnormalities. Treatment of thyroid storm is multimodal and is best managed by the endocrinologist and medical intensivist. Initial medical and supportive therapies are directed at stabilizing the patient, correcting the hyperthyroid state, managing the systemic decompensation, and treating the underlying cause. Once this has been achieved, definitive treatment in the form of radioactive ablation or surgery should be undertaken. We describe a case of thyroid storm in a young man that was precipitated by a motor vehicle accident.