Filters
Results 1 - 10 of 19
Results 1 - 10 of 19.
Search took: 0.034 seconds
| Sort by: date | relevance |
[en] We prove that four-dimensional Friedmann-Robertson-Walker solutions to ghost-free superstring and heterotic string effective actions are stable when compactified on a torus. We also consider the case of more general compactifications, and argue that the requirement of stability may have a role in determining the geometry of the compactification. We also discuss the effect of removing ghosts from string actions by field redefinitions. (orig.)
Journal
[en] The reported incidence of thyroid carcinoma in Hashimoto's thyroiditis varies widely. For this reason the specific subpopulation of patients with Hashimoto's thyroiditis and a solitary cold nodule was analyzed. Between 1972 and 1984 we operated on 146 consecutive patients with solitary cold nodules and Hashimoto's thyroiditis. There were 47 carcinomas, for an incidence of 32%. The mean age of the 146 patients was 43 1/2 years (median 44 years), with 126 females and 20 males. There was a history of prior head and neck radiation exposure in 54 patients, with a 33% incidence of thyroid carcinoma. The 92 patients without a history of radiation exposure had a 31.5% incidence of carcinoma. The frequency of multicentricity (bilateralism) was 33% in the group that underwent radiation and 24% in the group that did not. To date, with a mean follow-up of 4.7 years, there have been no deaths and no evidence of recurrence. In conclusion, we report a 32% incidence of thyroid carcinoma in patients with Hashimoto's thyroiditis and a solitary cold nodule, with no apparent difference between the patients with or without a history of radiation exposure, although there was a higher incidence of bilateralism (33% versus 24%) in the carcinomas of the patients with a history of head and neck irradiation. We suggest that the operative management of these patients is total thyroidectomy for those with a history of head and neck radiation and thyroid lobectomy for patients with no history of radiation, followed by contralateral lobectomy if a carcinoma is demonstrated
Journal
[en] We consider the effect of field redefinitions on the general form of the torsion dependent terms in the O(R3) string action. (orig.)
Journal
[en] During a period of 20 years (1965-1985), 206 consecutive patients were operated on for radiation-associated nodular thyroids. The ages ranged between 8 and 76 years (mean 38.7). there were 136 women and 70 men. The average duration between radiation exposure and operation was 27 years. The operations performed were total thyroidectomy (192) or, in patients who had undergone a previous lobectomy in another institution, another lobectomy (14). In addition, 25 patients required a neck dissection for nodal metastases and 27 underwent simultaneous subtotal parathyroidectomy for coexistent hyperparathyroidism. The pathologic findings were: 87 (42.2%) carcinoma (73 papillary, 13 follicular, 1 undifferentiated); 92 (44.7%) follicular adenomas; and 27 (13.1%) thyroiditis. To date, with an average follow-up of 6 years (0.5-31 years), only two patients have expired from recurrent disease. A third died of unrelated cause. A comparison of the first 100 patients (12 years) with the last 106 patients (8 years) demonstrated that the incidence of carcinoma has dropped from 48 to 37%, the incidence of lymph node metastases has decreased from 35 to 26%, and the incidence of bilaterality has fallen from 75 to 54%. On the basis of this series, it was concluded that total thyroidectomy is still indicated for radiation-associated nodular thyroids. However, if the trend of decreasing incidence, bilaterality, and metastatic disease persists, this approach may have to be reevaluated in the near future
Journal
[en] Forty-four patients with primary hyperparathyroidism were followed for 18 to 126 months after subtotal or total parathyroidectomy and parathyroid autotransplantation. Indications for autotransplantation included the devascularization of parathyroid glands during concomitant thyroid lobectomy or total thyroidectomy and the excision of the only remaining parathyroid tissue in patients with persistent hyperparathyroidism after previous unsuccessful parathyroidectomies. Before implantation, all parathyroid tissue was histologically evaluated by frozen-section light microscopy with hematoxylin and eosin stain. Fifteen patients had histologically normal implants; to date none of these patients have developed recurrent hyperparathyroidism. Twenty-nine patients had either adenomatous or hyperplastic parathyroid tissue used for implants; two of these patients developed graft-dependent recurrent hyperparathyroidism 4 and 7 years later. In both patients the grafts were preoperatively localized by thallium scanning and their resection restored eucalcemia. One hundred thirty-one patients from 11 series in the current literature had a cumulative incidence of 17.5% for presumed graft-dependent recurrence and a 9.2% incidence of graft excision followed by eucalcemia. In comparison, in the present series the incidence of graft-dependent recurrent hyperparathyroidism in patients with either adenomatous or hyperplastic implants stands at 6.9%. In contrast, in 15 patients with normal parathyroid tissue implants, the incidence was zero
Journal
[en] The merit of the preoperative localization of parathyroid tumors with thallium-technetium subtraction imaging is a subject of current debate in the treatment of primary hyperparathyroidism. Eighty patients with hyperparathyroidism underwent preoperative subtraction scintigraphy with 201Tl Cl and /sup 99m/TcO4; scan results were correlated with the operative identification and histopathology of the resected parathyroid tissue. The true-positive, false-positive and false-negative rates of these scans were compared between patients with tumors in normal and ectopic anatomic locations and between patients undergoing an initial and reoperative neck exploration. The scan was clearly valuable in patients with one or more prior neck explorations. True-positive scans were obtained in seven (77%) of nine such patients. The scan was also valuable in patients who had ectopic tumors (six mediastinal, seven intrathyroid, and two in the carotid sheath). Twelve (80%) of these 15 ectopic tumors were correctly localized either prior to their first operation or before subsequent explorations. In contrast, only 33 (50%) of 65 patients had a true-positive scan prior to their first operation and when the tumor was not in an ectopic location. In summary, in this series, the thallium-technetium scan was correct in only 50 per cent of patients undergoing an initial operation. However, it was positive in 77 per cent of patients who had at least one prior neck exploration and in 80 per cent of patients with an ectopic parathyroid tumor. These results support the selective use of this valuable imaging and localization tool
Journal
[en] Over a period of 32 years from 1954 to 1986, 65 patients under the age of 21 years, 52 girls and 13 boys, were operated for nodular thyroids: the overall incidence of carcinoma was 37 per cent. It was 46 per cent in those patients presenting with a solitary nodule. Among the 24 patients with a malignancy, the carcinoma was of the papillary variety in 63 per cent, follicular in 25 per cent and medullary in 12 per cent. Two thirds of the patients had metastatic disease at the time of presentation. All patients with thyroid carcinoma were treated with total thyroidectomy. Other measures included neck dissection and radioactive iodine. When the eight patients with a history of head and neck irradiation and the three patients with medullary carcinoma were excluded, the incidence of carcinoma was 28 per cent. In summary, in spite of the decline in radiation associated cases, the incidence of carcinoma in nodular thyroid disease in the population under 21 years, remains at the relatively high figure of 28 per cent
Journal
| 1 | 2 | Next |