Biomedical subjects

G B Thompson

Publications and source records attributed to G B Thompson.

At least 19 recordsLinked to original sources

PubMed2006

Malignant potential of solid pseudopapillary neoplasm of the pancreas.

BACKGROUND: Solid pseudopapillary neoplasms of the pancreas are rare malignant lesions of the pancreas that typically occur in young women. Large series from any one centre are notably absent in the literature. The aim of this study was to determine long-term outcomes of operative therapy. METHODS: The records of all 14 patients diagnosed with pseudopapillary neoplasms of the pancreas over 17 years were reviewed. RESULTS: Thirteen of the 14 patients were female and the mean age at diagnosis was 30 years. Solid pseudopapillary neoplasm was suspected in only half of these patients before operation. On computed tomography, ultrasonography and/or magnetic resonance imaging, three lesions were solid, three were largely cystic, and five had solid and cystic components. All 14 patients underwent surgical exploration and curative resections were possible in 13, including distal pancreatectomy in nine, pancreaticoduodenectomy in three and resection of a local intraperitoneal recurrence in one patient. After follow-up ranging from 3 months to 20 years, 12 patients were alive, including one who had undergone re-exploration and resection of local and subcutaneous recurrences 9 years previously. CONCLUSION: Solid pseudopapillary neoplasm of the pancreas should be considered in the differential diagnosis of any solid or partly cystic pancreatic mass in women aged less than 35 years. An attempt at en bloc resection without formal lymphadenectomy should be undertaken, including resection of synchronous or metachronous distant metastases.

Adolescent↗

PubMed2006

Bariatric surgery at the extremes of age.

The safety and efficacy of bariatric surgery in adolescents and especially in Medicare population have been challenged. Our aim was to determine short-term (30-day) and long-term outcomes of bariatric surgery in patients>or=60 years and or=60 years and 12 patients or=60 years and all 12 adolescents returned the questionnaire (92%) at a mean of 5 years (range 1-19 years). For patients>or=60 years, 30-day mortality was 0.7%, serious morbidity delaying discharge was 14%, and 5-year mortality was 5%. At a mean of 5 years, body mass index (BMI in kg/m2) decreased from a mean (+/-SEM) of 46+/-1 to 33+/-1 with a 51% resolution of weight-related comorbidities and an 89% subjective overall satisfaction rate. In patients<or=18 years, all with serious comorbidities, there were no deaths and no serious complications. BMI decreased from 55 (range 39-74) to 36 (range 27-53) at 4 years (range 1-8 years). Resolution of weight-related comorbidities was 82%, and satisfaction with outcome was 83%. Thirty-day hospital mortality (<1%) and 5-year mortality (5%) were much lower than reported previously in the senior population, with acceptable morbidity and importantly, with satisfactory outcomes. Bariatric surgery is safe and effective at high volume centers for patients with morbid obesity at both extremes of age.

Adolescent↗

PubMed2005

Strategies for fabricating atom probe specimens with a dual beam FIB.

A FIB-based lift-out method for preparing atom probe specimens at site specific locations such as coarse precipitates, grain boundaries, interphase interfaces, denuded zones, heat affected zones, implanted, near surface and subsurface regions, shear bands, etc. has been developed. FIB-based methods for the fabrication of atom probe specimens from thin ribbons, sheet stock, and powders have been developed.

Journal Article↗

PubMed2004

Some aspects of atom probe specimen preparation and analysis of thin film materials.

Some of the factors in the preparation of atom probe specimens of metallic multilayer thin films have been investigated. A series of Ti/Nb multilayer films were sputtered deposited on n-doped Si [001] substrates with either 5 or 0.05Omega cm resistivity. Each wafer was pre-fabricated into a series of 5 microm x 5 microm x approximately 80 microm island posts by photolithography and reactive ion etching. Once the film was grown on the wafer, a Si post was mounted to either a tungsten or stainless steel fine tip needle that was mechanically crimped to a Cu tube for handling. The specimen was then loaded into a Focus Ion Beam instrument where a sacrificial Pt cap was in situ deposited onto the surface of the film and subsequently annularly ion milled into the appropriate geometry. The Pt cap was found to be an effective method in reducing Ga ion damage and implantation into the film during milling. The multilayers deposited on the high resistivity Si exhibited uncontrolled field evaporation which lead to high mass tails in the mass spectra, a reduction in the mass resolution, high background noise, propensity for "flash-failure", and a variation in the apparent layer thickness as the experiment elapsed in time. The multilayers deposited on lower resistivity Si did not suffer from these artifacts.

Mass Spectrometry↗

PubMed2003

Preoperative detection of pancreatic insulinomas on multiphasic helical CT.

OBJECTIVE: The objective was to analyze enhancement characteristics of insulinomas and to determine the ability of multiphase CT to localize these tumors. MATERIALS AND METHODS: Prospective interpretations of multiphase helical CT scans were reviewed in 30 patients who had insulinomas resected over a 5-year period. CT scans were retrospectively reviewed to determine enhancement characteristics, tumor conspicuity in each phase of enhancement, and potential causes for false-negative findings. RESULTS: Sixty-three percent (19/30) of tumors were identified on CT prospectively. An additional six tumors were visualized in retrospect, allowing characterization of 25 (83%) of 30 tumors. Most tumors were hyperdense on at least one phase (n = 19), three tumors were hypoattenuating, and three were isodense and pedunculated. Insulinomas were most conspicuous on the early phase in 15 patients and in the portal venous phase in three. All tumors that underwent pancreatic phase imaging were seen (13/13), whereas three of 18 arterial and six of 25 portal venous phase findings were inconclusive for tumor. In the six examinations with false-negative findings in which the tumor could be seen in retrospect, two tumors were isodense and pedunculated, three were in close proximity to vessels, and one had a cystic appearance. CONCLUSION: Multiphasic CT has a moderate sensitivity in the detection of insulinomas. Most tumors are more conspicuous on the earlier phases of enhancement. The pancreatic phase may be more useful than the arterial phase. Potential sources of false-negative results include tumors adjacent to vessels, pedunculated morphology, or nonhyperattenuating lesions.

Adult↗

PubMed2002

Surgical management in Graves' disease.

Graves' disease is most often managed with radioiodine in the United States today. Surgical therapy, however, is a safe and effective form of treatment when performed by an experienced thyroid surgeon. Surgery can be particularly helpful when rapid control of hyperthyroidism is essential, in large gland disease, in children and in women of child-bearing age.

Antithyroid Agents↗

PubMed2001

Primary aldosteronism: factors associated with normalization of blood pressure after surgery.

BACKGROUND: Hypertension often persists after adrenalectomy for primary aldosteronism. OBJECTIVE: To determine factors associated with resolution of hypertension after adrenalectomy for primary aldosteronism. DESIGN: Retrospective cohort study. SETTING: Tertiary care referral center in Rochester, Minnesota. PATIENTS: All patients who underwent adrenalectomy for primary aldosteronism between 1 January 1993 and 31 December 1999. MEASUREMENTS: Preoperative plasma renin activity, plasma and urinary aldosterone concentrations, and adrenal imaging. Follow-up blood pressure, measured at a clinic visit or at home, was reviewed. RESULTS: 97 adrenalectomies were performed, and follow-up was available in 93 patients. Hypertension was resolved at follow-up (blood pressure < 140/90 mm Hg) without use of antihypertensive agents in 31 of 93 patients (33%). According to a stepwise multivariable logistic regression analysis adjusted for duration of follow-up, resolution of hypertension was independently associated with family history of hypertension in no more than 1 first-degree relative (odds ratio [OR], 10.9; P < 0.001) and preoperative use of two or fewer antihypertensive agents (OR, 4.7; P = 0.005). Additional factors associated with resolution of hypertension based on univariate analysis included younger age, shorter duration of hypertension, higher preoperative ratio of plasma aldosterone concentration to plasma renin activity, and higher urine aldosterone level (P < 0.05). CONCLUSIONS: Resolution of hypertension after adrenalectomy for primary aldosteronism is independently associated with a lack of family history of hypertension and preoperative use of two or fewer antihypertensive agents.

Adenoma↗

PubMed2001

Adrenocortical carcinoma: surgical progress or status quo?

HYPOTHESIS: Outcome of patients with adrenocortical carcinoma (ACC) has improved with the advent of more widely available and higher quality imaging. Operative management strategies and use of adjuvant therapy have not changed. DESIGN: Retrospective review of patient histories, imaging studies, operative data, adjuvant therapy, and outcomes at a single institution. Follow-up was complete for a mean of 53 months. Data was compared with prior institutional experience. SETTING: Tertiary care referral center. PATIENTS: All patients undergoing operative management for ACC during the period from 1980 to 1996. MAIN OUTCOME MEASURES: Determinants of recurrence, survival, and the effect of adjuvant therapy on overall outcome. RESULTS: Fifty-eight patients (30 men, 28 women) with a mean age of 53 years underwent primary operative management for ACC. Functional tumors were identified in 27 patients (47%). Mean tumor size was 12.5 cm. Stage according to the TNM staging system (AJCC Cancer Staging Manual) at presentation was I (n = 0), II (n = 30), III (n = 7), and IV (n = 21). Surgical management included curative resection in 41 (71%), noncurative resection in 14 (24%), and open biopsy in 3 (5%). Perioperative mortality was 5%. Recurrence occurred in 30 patients (73%) with a median time to recurrence of 17 months. Five-year survival by the Kaplan-Meier method was 37%. Prognostic factors (P<.05) included functional status, stage, and chemotherapy in stage III/IV patients. When compared with our prior institutional experience (1960-1980), current patients were more likely to present with stages I to II (52% vs. 34%), have curative resections (71% vs. 50%), and have improved 5-year survival (37% vs. 16%). CONCLUSIONS: (1) Surgical resection remains the principal treatment for stage I to III disease. (2) Adjuvant therapy may improve survival in patients with stage III or IV disease. (3) Current patients were more likely to present at an earlier stage, undergo curative resections, and have improved 5-year survival than institutional historical comparisons.

Adolescent↗

PubMed2001

Cushing syndrome due to ectopic adrenocorticotropic hormone secretion.

Cushing syndrome (CS) caused by ectopic adrenocorticotropic hormone (ACTH) production (EA) poses major challenges diagnostically by mimicking the pituitary-dependent form of CS and therapeutically by producing severe, life-threatening hypercortisolemia. This retrospective follow-up study describes the clinical characteristics and course of EA in a large referral center. Computer-based cross-index codes for EA, CS, and bilateral adrenalectomy were used to identify patients treated at the Mayo Clinic between 1956 and 1998. EA was confirmed in 106 patients. Gender distribution showed a slight female predominance (61:45). Bronchial carcinoid was the most frequent cause of EA (25%), followed by islet cell cancer (16%), small-cell lung carcinoma (11%), medullary thyroid cancer (8%), disseminated neuroendocrine tumor of unknown primary source (7%), thymic carcinoid (5%), pheochromocytoma (3%), disseminated gastrointestinal carcinoid (1%), and other tumors (8%). No tumor was found in 16% of patients. Altogether, 28 patients were managed medically, and the others underwent curative tumor resection (13 patients) or bilateral adrenalectomy (65 patients). Surgically treated patients had longer survival, but this was most likely affected by treatment bias. The diagnoses of CS and ACTH-secreting neoplasm were usually concurrent, although, there were remarkable cases in which the two conditions were diagnosed several years apart. Curative resection of the tumor producing EA was possible in a small proportion of patients (12%). When curative resection is not possible, patients who are reasonable surgical candidates are likely to benefit from adrenalectomy. Additional experience with bilateral laparoscopic adrenalectomy should increase the number of patients who benefit from adrenal-directed surgery.

ACTH Syndrome, Ectopic↗

PubMed2001

Cystic neoplasms of the pancreas: benign to malignant epithelial neoplasms.

Clinical presentation and state-of-the-art imaging permit the differentiation of most cystic pancreatic neoplasms not only from other cystic pancreatic disorders but also from one another. The differentiation of serous cystic lesions from the mucinous neoplasms (cystadenoma or carcinoma and IPMT) is crucial because of the radically different biological characteristics of these two neoplasms. Although mucinous cystic neoplasms should be resected because of their premalignant or overtly malignant tendency, most patients with serous neoplasms require no operative intervention unless they are symptomatic. IPMT is best treated by a total pancreatectomy, although lesser subtotal resections should be strongly considered depending on patient age, medical comorbidity, and psychosocial situations.

Adenocarcinoma, Mucinous↗

PubMed2001

Anaplastic thyroid carcinoma: a 50-year experience at a single institution.

BACKGROUND: Anaplastic thyroid carcinoma (ATC) is among the most aggressive of human malignancies. However, there have been few large studies of histologically well-defined ATC. We report the results of a 50-year experience of this lethal malignancy. METHODS: We reviewed all cases of ATC managed in this institution between 1949 and 1999. One pathologist (J.R.G.) reviewed all pathologic material. Clinical details were obtained from medical records, and current status of all patients was determined. RESULTS: There were 134 cases, with a female-to-male ratio of 1.5:1 and a mean age of 67 years. Benign thyroid disease was present in 27 cases (20%) and well-differentiated thyroid carcinoma in 31 (23%). Sixty-two patients (46%) had distant metastases at diagnosis, and 98% of the tumors were locally invasive. Primary treatment was surgical for 96 patients (72%). Complete resection was achieved in 29 cases (30%), with "minimal residual disease" in 25. Neither extent of operation nor completeness of resection affected survival (P > .4). Postoperative radiotherapy gave slightly longer median survival (5 vs 3 months), which was not significant (P < .08). Multimodal therapy, including operation, chemotherapy, and radiotherapy, did not improve survival. CONCLUSIONS: The outlook for patients with ATC remains grim. Novel treatments for ATC are desperately needed.

Adult↗

PubMed2001

Reexploration for symptomatic hematomas after cervical exploration.

BACKGROUND: Hematomas requiring reoperation affect 1% of patients undergoing cervical exploration. This complication has implications for the trend toward outpatient procedures. METHODS: Retrospective review of 13,817 patients undergoing thyroidectomy and parathyroidectomy at this institution (1976 to 2000) identified 42 patients with hematomas requiring reoperation. Case controls (n = 42) were matched for age, gender, and type and year of operation. Perioperative risk factors and outcome were compared. RESULTS: Study and control groups were composed of 18 men and 24 women (mean age, 62 years) undergoing thyroidectomy (n = 21) or parathyroidectomy (n = 21). Comparison of perioperative risk factors yielded no significant difference between groups. Symptoms included respiratory distress in 21 patients, pain/pressure in 11, dysphagia in 8, and drainage in 6. Mean time to symptom onset was 17 hours (range, 10 minutes to 5 days). Eighteen hematomas presented within 6 hours postoperatively, 16 between 7 and 24 hours, and eight beyond 24 hours. The bleeding source was arterial in 11 patients, venous in 8, thyroid/soft tissue in 13, and indeterminate in 10. Mean hospital stay was longer in the study group (7.2 vs 3.6 days, P = .004). The number of patients with complications was higher in the study group (17 vs 7, P = .03). No single complication reached significance: hypocalcemia (8 vs 3, P = .12), wound infection (3 vs 0, P = .87), and others (10 vs 5, P = .21). CONCLUSIONS: (1) No factor foreshadowed this complication. (2) The definition of a high-risk population remains obscure. (3) Sixty percent presented beyond 6 hours postoperatively. (4) Reexploration increased morbidity and lengthened hospital stay.

Adult↗

PubMed2001

Benign paragangliomas: clinical presentation and treatment outcomes in 236 patients.

Paragangliomas are rare tumors that arise from extraadrenal chromaffin cells. We examined the clinical characteristics, location, treatment, and outcome of 236 patients (141 females, 60%) with 297 benign paragangliomas evaluated at the Mayo Clinic during 1978-1998. The mean age (+/-SD) at diagnosis was 47 +/- 16 yr. Of the 297 paragangliomas, 205 were in the head and neck region, and 92 were below the neck. Paragangliomas were discovered and diagnosed incidentally on imaging studies in 9% of patients. Biochemical screening was performed in 128 patients; 40 patients (17% of the total and 31% of those screened) had hyperfunctional tumors. Of the 40 patients with tumoral catecholamine excess, 38 had documented hypertension. In patients identified with catecholamine-secreting paragangliomas, the sensitivities achieved by measurements in the 24-h urine collection were 74% for total metanephrines, 84% for norepinephrine, 18% for dopamine, and 14% for epinephrine. Multiple imaging modalities were used for tumor localization. The false negative rates were 0% for magnetic resonance imaging, 5.8% for computed tomography, 3.4% for angiography, 10.7% for ultrasonography, and 39% for radioactive iodine-labeled metaiodobenzylguanidine scintigraphy. Of 192 patients (81.4%) with follow-up data (mean, 43.9 months; range, 0.5-240), operative cure was achieved in 133 (69%). Of the 59 patients without cure, 23 had persistent disease, 5 had recurrent disease, 16 had multiple persistent synchronous tumors, and 15 subsequently developed metachronous tumors. In conclusion, most paragangliomas are nonhypersecretory and located in the head and neck region. Magnetic resonance imaging was associated with the lowest false negative rate, and metaiodobenzylguanidine was the least sensitive imaging study. A significant proportion of patients (31%) has persistent or recurrent disease, and long-term follow-up is important.

Adolescent↗

PubMed2001

Laparoscopic adrenalectomy for adrenocorticotropin-dependent Cushing's syndrome.

Bilateral adrenalectomy is indicated for the treatment of ACTH-dependent Cushing's syndrome when the tumorous source of ACTH hypersecretion cannot be identified or removed. Potential advantages of laparoscopic over open adrenalectomy include shorter hospitalization, decreased requirement for postoperative analgesia, and decreased postoperative morbidity due to incisional complications. Bilateral laparoscopic adrenalectomy performed for the treatment of ACTH-dependent Cushing's syndrome was attempted in 19 patients at our institution between 1995 and 1998. Conversion to an open procedure was required in three patients. All patients who underwent bilateral laparoscopic adrenalectomy were subsequently followed to assess the outcome of this intervention. Twelve patients with pituitary-dependent Cushing's syndrome and four with ectopic ACTH syndrome underwent successful bilateral laparoscopic adrenalectomy. All patients experienced resolution of the signs and symptoms (e.g. proximal myopathy, hirsutism, and emotional lability) of Cushing's syndrome as well as weight loss, improved glucose tolerance, and improved control of blood pressure. No residual cortisol secretion was detected in the patients. Bilateral laparoscopic adrenalectomy is a safe and effective treatment for Cushing's syndrome when the ACTH-secreting neoplasm cannot be removed.

ACTH Syndrome, Ectopic↗

PubMed2001

Pathologic features and expression of insulin-like growth factor-2 in adrenocortical neoplasms.

We analyzed a series of adrenocortical neoplasms to compare the clinicopathologic features and the expression of insulin-like growth factor-2 (IGF-2) in adrenocortical adenomas and carcinomas. IGF-2 is a growth factor commonly expressed in many tumors including adrenal cortical and medullary neoplasms. Formalin-fixed paraffin-embedded tissues from 64 adrenocortical adenomas and 67 adrenocortical carcinomas were analyzed. The carcinomas were histologically graded from 1 to 4 based on mitotic activity and necrosis. Tumor weight, size, and follow-up information were obtained by chart review. Expression of IGF-2 was detected by immunohistochemistry with the avidin-biotin-peroxidase complex method and a monoclonal antibody against IGF-2. Adrenocortical carcinomas were larger (mean: 13.1 cm, 787 g) than adenomas (mean: 4.2 cm, 52 g) (p < 0.001). Inpatients with adrenocortical carcinomas, high tumor grade (3 or 4) (p = 0.01) was associated with decreased survival. Expression of IGF-2 was higher in adrenocortical carcinomas than in adenomas (p < 0.001). These results show that tumor size and weight along with expression of IGF-2 protein are useful features to assist in distinguishing between adrenocortical adenomas and carcinomas, and that high tumor grade is a predictor of survival in adrenocortical carcinomas. However, single immunohistochemical markers such as IGF-2 or single histopathologic features cannot by themselves separate adrenocortical adenomas from carcinomas, and a combination of clinical, gross, and microscopic features are needed to establish the diagnosis in difficult cases.

Adolescent↗

PubMed2001

Pheochromocytoma in a patient with end-stage renal disease.

Pheochromocytoma is a rare tumor. To our knowledge only 15 cases have been reported in patients with end-stage renal disease (ESRD). We describe a 46-year-old woman with ESRD and a history of paroxysmal and difficult-to-control hypertension. During anesthesia for a surgical procedure, the patient experienced blood pressure lability with systolic blood pressures ranging from 76 to 360 mm Hg. Serum catecholamine concentrations were 2,698 pg/ mL (reference value, <750 pg/mL) for norepinephrine, 33 pg/mL (<110 pg/mL) for epinephrine, and 55 pg/mL (<30 pg/mL) for dopamine. The concentrations of plasma metanephrines were 6.84 nmol/L (<0.50 nmol/L) for metanephrine and 14.64 nmol/L (<0.90 nmol/L) for normetanephrine. Abdominal computed tomography showed a right-sided, 4-cm mass posterior to the infrahepatic inferior vena cava. Following blood pressure control with alpha- and beta-adrenergic blockade, the mass was removed. Pathologic examination demonstrated the mass was a pheochromocytoma. The maximum postoperative systolic blood pressure was 160 mm Hg. Postoperative plasma normetanephrine concentration was 2.80 nmol/L, and metanephrine was obscured by interfering substances. This case report and literature review emphasizes the difficulty in diagnosing pheochromocytomas in patients with ESRD despite the myriad of available diagnostic tests.

Blood Chemical Analysis↗

PubMed2000

Learning to read with underdeveloped phonemic awareness but lexicalized phonological recoding: a case study of a 3-year-old.

Case studies on very precocious readers are useful for examining what sources of knowledge and processes are necessary in the acquisition of reading. This is a case study of a 40-month-old child with a word reading age of 8 years 6 months. Tests indicated that she had no phoneme awareness beyond initial phonemes, and that her productive spelling was undeveloped. In reading she was highly proficient at rapid phonological recoding, both by correspondences that were contextually sensitive and those that were not. The former determined her high level of irregular pronunciations for irregular consistent non-words. Experiments indicated that she had well-specified orthographic lexical representations. It was concluded that her phonological recoding was an implicit process based on sublexical relations induced from her lexical representations rather than explicitly taught letter-sound correspondences. The implications of the results for major developmental models of reading acquisition are examined.

Analysis of Variance↗

PubMed2000

What prognostic factors are important in duodenal adenocarcinoma?

HYPOTHESIS: Survival of patients with adenocarcinoma of the duodenum depends on the ability to perform a complete resection and the tumor stage DESIGN: Retrospective case series. SETTING: Tertiary care referral center. PATIENTS: A cohort of 101 consecutive patients (mean age, 62 years), undergoing surgery for duodenal adenocarcinoma from January 1, 1976, through December 31, 1996. Patients with ampullary carcinoma were specifically excluded. Mean duration of follow-up was 4 years. INTERVENTIONS: Surgery was curative in 68 patients (67%) and palliative in 33 patients (33%). Of the curative group, 50 patients (74%) underwent radical surgery, ie, 30 (60%), pancreaticoduodenectomy; 15 (30%), pylorus-preserving pancreaticoduodenectomy; and 5 (10%), total pancreatectomy. A more limited resection procedure was used in 18 patients (26%) involving a segmental duodenal resection in 15 (83%) and a transduodenal excision in 3 (17%). patient survival, and correlation with patient and tumor variables using univariate and multivariate analysis. RESULTS: Actuarial 5-year survival for the curative group was 54%. Only 1 patient in the unresected group survived beyond 3 years. Nodal metastasis (P = .002), advanced tumor stage (P<.001), positive resection margin (P = .02), and weight loss (P<.001) had a significant negative impact on survival in multivariate analysis. Tumor grade, size, and location within the duodenum had no impact on survival. Patient age and tumor depth of invasion influenced survival in univariate analysis, but lost their prognostic significance in multivariate analysis. CONCLUSIONS: Metastasis to lymph nodes, advanced tumor stage, and positive resection margins are associated with decreased survival in patients with duodenal adenocarcinoma. An aggressive surgical approach that achieves complete tumor resection with negative margins should be pursued. Pancreaticoduodenectomy is usually required for cancers of the first and second portion of the duodenum. Segmental resection may be appropriate for selected patients, especially for tumors of the distal duodenum.

Adenocarcinoma↗