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Biomedical subjects

R K Davis

Publications and source records attributed to R K Davis.

At least 19 recordsLinked to original sources
PubMed2000

Functional outcome and survival after pharyngolaryngoesophagectomy for cancer.

BACKGROUND: Surgical resection of the larynx, hypopharynx and cervical esophagus, or pharyngolaryngoesophagectomy (PLE), with pharyngogastric anastomosis (PGA) offers a means of controlling local and regional carcinoma of the upper aerodigestive tract (UADT). We reviewed our experience with PLE for carcinoma of the UADT to evaluate functional outcome and survival. METHODS: Patients undergoing PLE from 1986 through 1999 were reviewed. Survivors completed questionnaires which graded their level of function and voice rehabilitation. Gastric emptying studies were performed with rates compared with normal controls. Survival curves were generated using the Kaplan-Meier method. RESULTS: Thirty-one patients underwent PLE during the study period. Twenty-nine patients had squamous cell carcinoma. Operative mortality was 0%. Thirty-day mortality was 9.6%. There were 2 anastomotic leaks (6.4%). All survivors reported normal ability to complete activities of daily living. Voice rehabilitation was acceptable in 7 of 10 survivors. Positive surgical margins resulted in decreased survival (P = 0.03). No other patient demographic or management variable altered survival. One-year, 5-year, and 10-year survival rates were 67%, 40%, and 18%, respectively. CONCLUSION: PLE with PGA for carcinoma of the UADT may be performed with low morbidity and mortality. Functional patient outcomes including gastric emptying, activities of daily living, and voice rehabilitation are acceptable.

Aged↗
PubMed1997

Intraoperative phototherapy: a comparative study of intravenous and topical photofrin II and aminolevulinic acid.

This study compares the systemic and topical application of photofrin II and aminolevulinic acid as an intraoperative adjuvant therapy in the C3H mouse radiation-induced fibrosarcoma model. Dose-development and time-dependent studies were first conducted followed by intraoperative phototherapy studies with photofrin II and aminolevulinic acid. Study results clearly show that intraoperative phototherapy after aminolevulinic acid topical application is significantly more effective than treatment with photofrin II given intravenously or topically (p < 0.05) in this animal tumor model. The concept of topical application of photosensitizers and the rationale for intraoperative adjuvant phototherapy are discussed.

Aminolevulinic Acid↗
PubMed1997

Endoscopic surgical management of glottic laryngeal cancer.

This article recounts the historical development of the endoscopic surgical management of stage I and stage II glottic cancer. The indications and surgical approach to treating stage I cancer and the rationale for extending the original limitations to the endoscopic treatment of highly selected stage II glottic cancers is described. The indications, technique, and outcomes of the endoscopic treatment of stage II glottic cancer are also presented.

Carcinoma in Situ↗
PubMed1995

Genetic abnormalities in sporadic parathyroid adenomas: loss of heterozygosity for chromosome 3q markers flanking the calcium receptor locus.

Inactivating mutations of the parathyroid cell calcium receptor (CaR) gene cause one form of familial benign/hypocalciuric hypercalcemia, and in homozygous form, cause neonatal severe primary hyperparathyroidism with parathyroid hyperplasia. Thus, we postulated that partial or total loss of CaR function might contribute to calcium insensitivity or even stimulate cell proliferation in sporadic parathyroid adenomas (PAds). To examine this possibility, we sought loss of heterozygosity (LOH) for markers flanking the CaR locus (3cen-3q21) in 35 PAds. We used 16 highly-polymorphic PCR-based markers in paired normal and tumor DNA, extracted from slices of archived surgical specimens. Nineteen to 24 of the DNA pairs were informative with at least one marker. In two informative pairs, we found LOH for markers D3S1303, D3S1267, or D3S1269, which are tightly-linked with and flank the CaR locus. In one tumor, deletion mapping confined the lost area between D3S1271 and D3S1238 (41.7 centimorgans, cM). In the other tumor, LOH spanned most of chromosome 3, ranging at least from D3S1307 to D3S1311 (271.4 cM). LOH was confirmed by repetition of the experiments and quantified by phosphorimaging. Thus, we found LOH encompassing the CaR locus in approximately 10% of sporadic PAds. These data are consistent with the hypothesis that loss of CaR function may occur in PAds, with functional consequences for calcium sensitivity and cell proliferation.

Adenoma↗
PubMed1994

Infrainguinal reconstruction with arm vein, lesser saphenous vein, and remnants of greater saphenous vein: a report of 257 cases.

PURPOSE: The purpose of this study was to evaluate the results of infrainguinal reconstructions with arm vein, lesser saphenous vein, and remnants of greater saphenous vein (ectopic vein grafts). METHODS: The records of 222 patients who underwent 257 bypasses were restrospectively reviewed. Most of the grafts were placed for rest pain or tissue loss (88%) and were secondary reconstructions (70%) to the infrapopliteal level (90%). Single-length vein grafts were constructed in 66% of cases, whereas 34% were composite vein grafts. RESULTS: Secondary graft patency was 70%, 52%, and 43% at 1, 3, and 5 years. Single-length grafts had significantly better patency rates at all intervals: 78% versus 56% at 1 year (p = 0.001), 60% versus 39% at 3 years (p = 0.004), and 52% versus 29% at 5 years (p = 0.002). The limb salvage rate was 69% at 5 years. CONCLUSIONS: Ectopic vein grafts with primarily arm vein are an acceptable alternative for infrainguinal reconstruction in the absence of suitable ipsilateral greater saphenous vein.

Adult↗
PubMed1994

Primary adenoid cystic carcinoma of the lacrimal sac: report of a case.

A 41-year-old white woman presented with a 1-month history of epiphora and a painless medial canthal mass on the left that was unresponsive to antibiotic treatment. Computerized tomography (CT) and magnetic resonance imaging (MRI) scans delineated a soft tissue mass with bony destruction originating in the area of the left lacrimal sac with extension into the maxillary and ethmoid sinuses and inferomedial orbit. Open biopsy of the mass revealed adenoid cystic carcinoma (ACC). On surgical exploration, the tumor was found to originate from the lacrimal sac wall. Radical surgery with wide excision of surrounding bone and periorbital tissue was performed in light of the histological diagnosis and tumor extension. Orbital exenteration was not performed in order to preserve the patient's left eye. A 6-week course of adjunctive radiotherapy was applied without complication. The patient was clinically and radiologically free of tumor at 1-year follow-up. This case represents only the third time that primary ACC arising from the lacrimal sac has been reported.

Adult↗
PubMed1994

Endoscopic treatment of supraglottic and hypopharynx cancer.

Transoral excision of supraglottic and hypopharynx cancer as a single modality is effective when lesions are selected for small size and endoscopic accessibility. Excisional biopsy with clear margins of larger supraglottic tumors in combination with postoperative radiotherapy provides an excellent treatment alternative for selected lesions in patients who are not candidates for open surgery. In this preliminary report, 45 cases using this minimally invasive approach are reviewed outlining oncologic rationale and functional advantages. A large bore tubed laryngoscope or the adjustable bivalve supraglottiscope was used along with a carbon dioxide laser in all cases. In 22 of the 45 patients (mostly T1), local en bloc excision of the primary cancer was performed as sole treatment on selected lesions of the supraglottis and hypopharynx. There were no local recurrences, however, 1 patient developed a neck recurrence and was salvaged by neck dissection. Twenty-three of the 45 patients had more extensive primaries (mostly T2, T3) and N0 necks. Transoral excisional biopsy was followed by full-course radiation therapy to the primary site and both necks. All 23 were followed a minimum of 2 years, and the median follow-up period was 58 months. Clear margins were obtained in 16 of 23, and there were no recurrences in the larynx. Two of 16 did fail in the neck and died despite neck dissection. Seven of 23 patients had positive margins and, despite full-course radiotherapy to the primary site and both necks, 5 of 7 failed locally or regionally. Two of the 7 died of their disease despite open salvage surgery. Therefore, 4 of 23 patients who underwent transoral excision of larger lesions followed by full-course radiotherapy died of recurrent cancer.

Combined Modality Therapy↗
PubMed1992

Computed tomography treatment planning in IR-192 brachytherapy in the head and neck.

Brachytherapy dose prescription and treatment planning lag behind the state-of-the-art for external beam therapy. As altered fractionation of external beam therapy improves patient outcome in head and neck cancer, there will be an increased need to compare the two radiotherapy techniques. Currently, implant techniques and dose prescription documentation are not uniform, dose prescription to a target volume is subjective, and implant quality is poorly understood and not routinely assessed. All contribute to a lack of scientifically rigorous brachytherapy clinical trials. Studies designed to combine tumor imaging and dosimetry data are important in the evolution of brachytherapy treatment planning. Head and neck implants, which often require nonparallel, arching, or looping source carriers for all but small tumors in order to encompass the target volume adequately, were used to evaluate the clinical utility and feasibility of computed tomography as a treatment planning tool in brachytherapy. Following placement of plastic afterloading tubes under general anesthesia, orthogonal radiographs with dummy sources in the afterloading tubes are obtained as customary for source localization. With the patient in the same position, axial CT scans are obtained with the dummy seeds still in place for treatment planning. The implant physician, using data from the pre-treatment diagnostic CT scan, outlines target areas on sequential images creating a 3-dimensional target volume. By superimposing anatomic data with isodose curves one can objectively define implant parameters important in clinical trials analysis. These include minimum target absorbed dose, implant uniformity, and treatment to target volume ratio. The results of the first 10 patients are presented and implications of these data regarding the analysis of implant technique, implant quality, and implant optimization are discussed. The technique as performed is laborious but practicable in the clinical research setting of head and neck implant. Further research efforts should improve, simplify, and objectify brachytherapy and hasten the time when rigorous multi-institutional brachytherapy trials will be reality.

Adult↗
PubMed1992

Multiple sclerosis in pregnancy: a review.

This case history discussed multiple sclerosis that began during pregnancy, in a patient with a history of juvenile rheumatoid arthritis. The etiology, epidemiology, pathophysiology, diagnosis, clinical course, and management of MS are reviewed from the point of view of an obstetrician, with emphasis on the interaction between MS and pregnancy. The similarities and differences between MS and rheumatoid arthritis, with respect to the effect of pregnancy on these diseases, is discussed. Because of the generally beneficial effect of pregnancy on MS and rheumatoid arthritis, and the frequent exacerbations of both diseases seen in the postpartum period, further studies of the relationship between pregnancy and these diseases may provide clues to the immunology and treatment of multiple sclerosis and other autoimmune diseases.

Female↗
PubMed1991

Endoscopic CO2 laser excisional biopsy of early supraglottic cancer.

Endoscopic CO2 laser excisional biopsy of selected early supraglottic cancer patients has been described. None of these patients experienced the perioperative morbidities of bleeding, airway obstruction, or aspiration beyond 3 or 4 days. All patients were treated with full-course standard irradiation therapy after their laser procedures. Our very preliminary data suggest that stage I and stage II patients are effectively treated with endoscopic CO2 laser excisional biopsy, whereas stage III patients should undergo open surgeries where medically possible.

Biopsy↗
PubMed1991

Serious soft tissue infections of the head and neck.

The head and neck contain a number of spaces that can be invaded by organisms of the mouth or by spread of cervical osteomyelitis. Infection in these spaces may progress from superficial infection to cellulitis to the formation of an abscess requiring immediate drainage. Spread of infection between spaces depends on anatomic location. Most patients require hospitalization and intravenous antibiotic therapy. Because a deep space infection may be occult, a high index of suspicion is required for diagnosis. Early recognition is necessary to avoid tissue damage, bacteremia or airway compromise. The possibility of deep space infection should be considered in any patient who does not respond to the usual treatment of an abscessed tooth or tonsillitis. This type of infection also should be considered in a toxic patient who has a fever of unknown origin, with or without blood cultures that show anaerobic organisms. Computed tomography or magnetic resonance imaging is usually necessary to locate the infection and to detect suppuration that will be amenable to surgical exploration and drainage.

Clinical Protocols↗
PubMed1991

Gastric emptying after gastric interposition for cancer of the esophagus or hypopharynx.

Transhiatal esophagectomy with primary anastomosis to the stomach (gastric pull-up) is an attractive surgical alternative to colic interposition in patients with cancer of the esophagus and hypopharynx. However, the lack of intrinsic gastric peristalsis and complaints by patients of postprandial regurgitation prompted us to measure the effect of body posture on the rates of gastric emptying in these patients. The rates of solid and liquid gastric emptying were measured in 14 patients who had undergone gastric interposition for esophageal and hypopharyngeal carcinoma. Rates of emptying were measured in both the supine and upright position using a dual-isotope radiolabeling technique. In these patients, the rate of gastric emptying of both solids and liquids was significantly slower in the supine position than in the upright position. Emptying in supine patients was also prolonged when compared with supine normal volunteers. Conversely, the upright rate of solid and liquid emptying in the patients was accelerated when compared with published values for upright normal volunteers. We conclude that gastric emptying after gastric interposition is dependent on upright posture after meals.

Adult↗
PubMed1990

Intraoperative phototherapy (PDT) and surgical resection in a mouse neuroblastoma model.

This study evaluates the effect of intraoperative photodynamic therapy (PDT) using the multiline argon laser (488-514 nm) or the argon-dye laser (630 nm) combined with surgical resection compared with surgical resection alone in reducing the incidence of C1300 neuroblastoma recurrence in mice. In the control groups, surgical resection alone resulted in 86% +/- 12% tumor recurrence. Surgical resection and intraoperative lasing without photosensitizer resulted in 75% +/- 27% tumor recurrence with the argon-dye laser and 55% +/- 18% recurrence with the multiline argon laser. In the treatment groups, surgical resection and intraoperative PDT at 630 nm resulted in 56% +/- 19% tumor recurrence whereas surgical resection and intraoperative PDT at 488-514 nm resulted in 21% +/- 7% tumor recurrence. The cause for the decrease in local recurrence in the control group using the multiline argon laser is unknown, but could it be due in part to hyperthermic effects. Intraoperative PDT was an effective adjunct to surgical resection in preventing local recurrence in this tumor model.

Animals↗
PubMed1990

Thyroid cancer: a computer-assisted review of 5287 cases.

Retrospective computer analysis of all reportable cases of thyroid cancer for the Rocky Mountain Cancer Data Systems between 1973 and 1983 was undertaken. Follow-up data were available for periods of 5 to 10 years. All major histologic findings are reviewed with regard to distribution, prognostic factors, mortality rates, and some treatment modalities. Interesting observations determined by this study include: (1) the significantly greater mortality rates seen in patients with thyroid cancer after 50 years; (2) the lack of increased mortality rates in young patients with differentiated cancer; (3) the poorer prognosis of male patients of equivalent age to female patients in all histologic types of cancer in the first 5 years; (4) the lack of sexual difference in influencing mortality rates after the first 5 years in differentiated cancers and lack of sex as a prognostic indicator in undifferentiated cancers; (5) the excellent prognosis of patients with localized differentiated and medullary cancers and a better-than-expected prognosis in the undifferentiated group; (6) the clear need for combined therapy (surgery and irradiation) in regional medullary cancer; (7) the observation that localized thyroid lymphoma had a higher mortality rate than had regional thyroid lymphoma; and (8) a significantly higher mortality rate in patients older than 79 years with differentiated cancer.

Adenocarcinoma↗
PubMed1990

Unilateral parathyroidectomy: the role of thallium-technetium subtraction scans.

The rationale for using the thallium-technetium subtraction scan as a preoperative localizing study in previously untreated patients with primary hyperparathyroidism is presented. The concept of unilateral parathyroidectomy is also presented, and the role of preoperative localizing studies in this approach to parathyroid surgery is carefully analyzed.

Adenoma↗