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Biomedical subjects

S H Levitt

Publications and source records attributed to S H Levitt.

At least 109 records · Page 6Linked to original sources
PubMed1984

The Lampe lecture. Radical radiation therapy in the treatment of laparotomy staged Hodgkin's disease patients.

In 1970, a policy for the treatment of Stage IIIA Hodgkin's disease patients at the University of Minnesota, which included complete staging procedures and extended field or total nodal irradiation (TNI), was introduced. Evaluation of the results 4 years later indicated that certain patients, especially those with large mediastinal masses and/or hilar disease, or who were spleen positive, were having higher recurrence rates than patients without these characteristics. In 1974, a new approach to treatment for patients with large mediastinal masses or spleen positive disease was instituted which involved treating the whole lung or hemi lung in patients with large mediastinal masses and/or hilar disease, and the liver in patients who had positive spleens. The results of this treatment modification are reported in this study. Long term follow-up reveals that this approach has led to a recurrence free survival and overall survival similar to that noted in patients treated with combined modality treatment without the obvious risk of subsequent leukemia related to combination chemotherapy and radiotherapy. In addition, the complications of the treatment are tolerable and do not demonstrate an increase over patients not treated in this manner. Radical radiation therapy is recommended as a treatment of choice for Stage IA, IIA, and IIIA patients with or without splenic involvement, and with or without hilar disease and/or large mediastinal masses with appropriate radiation field modification to adjust for disease extent.

Actuarial Analysis↗
PubMed1984

Changes in acidity of mouse tumor by hyperthermia.

The intratissue pH of SCK tumor and leg muscle of unanesthetized mice were determined before, during and after hyperthermia with the use of bulb type pH microelectrodes having pH-sensitive hemisphere 20-40 micron in outer radius. Intratumor pH was heterogeneous throughout tumor (range, 6.60-7.38; average, 6.96), and was more acidic than the intramuscle pH of mouse leg (average, 7.46). Hyperthermia at 43.5 degrees C for 30 min induced a further increase in acidity (decrease in pH of about 0.2 units) in tumor but not in muscle. The heat-induced acidity in tumor lasted for 12 hr following hyperthermia and then recovered to almost control pH value 24 hr after heating. The cause of the increase in acidity in the heated tumors is not clear, but it appears to result from an increase in the contents of acidic metabolites and a sluggish drainage of them due to induced vascular damage. The increased acidity in the heated tumors may inhibit the repair of thermal damage and sensitizes the tumor cells to subsequent heating.

Acid-Base Equilibrium↗
PubMed1984

Liver irradiation in stage IIIA Hodgkin's disease patients with splenic involvement.

Curative treatment for Hodgkin's disease for patients who are pathology-staged IIIA, spleen-positive, consisted of total nodal irradiation (TNI) alone at the University of Minnesota Hospitals prior to 1975. This approach has been modified since 1975 to give low-dose irradiation to the liver in addition to TNI because of the high recurrence rate with TNI alone. Recurrence-free survival improved significantly when the liver was irradiated as compared to results with TNI alone (78% vs. 41% at 5 years, p = 0.004). The 5-year, overall survival was not significantly different in the two groups (90% vs. 80% at 5 years, p = 0.373). Various prognostic factors were examined. Patients who received liver treatment had statistically significant improvement in recurrence-free survival as compared to patients who did not receive liver treatment in the following categories: anatomic substage IIIA1, histologic classification of nodular sclerosis, male gender, age less than 40, number of primary sites, and extent of splenic disease. However, these factors failed to show clinical significance as prognostic factors. We conclude that TNI with low-dose liver irradiation should be used as the primary modality of treatment of Hodgkin's disease, pathology-staged IIIA patients. We conclude that chemotherapy should be reserved for recurrences in view of the excellent current results and the lesser risk from treatment, especially the risk of carcinogenesis.

Adolescent↗
PubMed1984

The impact of extraperitoneal surgical staging on morbidity and tumor recurrence following radiotherapy for cervical carcinoma.

From 1971 through 1981, 83 nonsurgically staged women with cervical cancer received extended-field radiotherapy on the basis of abnormal lymphangiogram, obstruction on intravenous pyelogram, or extensive pelvic tumor volume. From 1978 through 1981, 61 surgically staged patients underwent radiation therapy; of these, the 21 with positive lymph nodes received periaortic radiation. No increase in morbidity was found in these patients. Survival, relapse rate, and sites of treatment failures were similar in the positive lymphangiogram group and in the surgically staged patients with positive nodes.

Adult↗
PubMed1983

Tangential fields. Improved reproducibility for breast-cancer treatment.

The authors describe an isocentric technique to set up tangential fields for breast-cancer therapy. The setup parameters (source-to-surface distance measured at the midline of the sternum, lateral shift of the treatment couch, and the gantry angle) are predetermined from a computed-tomographic image and a transverse contour which is obtained under treatment-like conditions. This procedure does not require breast immobilization and does not rely on skin marks on the breast.

Breast Neoplasms↗
PubMed1983

Skin radioprotection by 5-thio-D-glucose.

The radioprotective effect of 5-thio-D-glucose on mouse skin was studied. Intraperitoneal injection of A/J mice with 1.5 g/kg of 5-thio-D-glucose 2 hr prior to X irradiation of the foot reduced early foot skin damage through Day 40 postirradiation by a dose modification factor of 1.3 +/- 0.1. Similarly, late foot deformity during Days 60-90 postirradiation was reduced by a factor of 1.2 +/- 0.1. The radioprotective effect of 5-thio-D-glucose was also compared with that of WR-2721, an aminothiol radioprotector, in CDF1 mice. An intraperitoneal injection of 1.5 g/kg of 5-thio-D-glucose reduced early radiation-induced skin damage by a dose modification factor of 1.2 +/- 0.1 as compared to that of 1.5 +/- 0.2 by 0.65 g/kg of WR-2721 in this strain of mice. 5-Thio-D-glucose is also known to specifically kill and radiosensitize hypoxic tumor cells. Consequently, this drug may be a useful radiotherapy adjuvant, reducing normal tissue damage and enhancing tumor control by minimizing hypoxic protection.

Amifostine↗
PubMed1983

Uptake of carbon monoxide by C3H mice following X irradiation of lung only or total-body irradiation with 60Co.

Carbon monoxide uptake (Vco) and ventilation rate (VR) of C3H mice were determined at 14 weeks following either X irradiation of lungs only or total-body irradiation with 60Co at different dose rates. Following localized X irradiation of lung at 97 cGy/min there was a reduction in Vco, which was inversely related to radiation dose, with a small reduction below control levels being detected at 7 Gy, the lowest dose tested. An increase in VR could be detected only at doses of 11 Gy, or more. Another group of animals received 11.5 Gy total-body irradiation at either 26.2 or 4.85 cGy/min followed by transplantation with syngeneic bone marrow. Following total-body irradiation, Vco was significantly reduced by about 37% at the higher dose rate and 23% at the lower dose rate. In contrast, a trend toward elevated VR was detected only at the higher dose rate. The results indicate that Vco is a sensitive indicator of radiation-induced lung injury and that under the experimental conditions used Vco is a more sensitive indicator of radiation-induced lung injury in C3H mice than VR.

Animals↗
PubMed1983

Effect of X irradiation and hyperthermia on vascular function in skin and muscle.

Vascular change by the combined treatments of radiation and hyperthermia was studied. The legs of rats were irradiated with 2000 rad of X rays in a single dose and heated at 43.0 degrees C for 1 hr at various times after irradiation, and the blood flow and vascular volume in the skin and muscle were determined with 125I-microspheres and 51Cr-RBC methods, respectively. Irradiation alone caused an immediate increase in blood flow and vascular volume in skin and muscle followed by a second increase during 2-4 weeks postirradiation. Heating also caused an immediate and profound increase in blood flow and vascular volume. When tissues were irradiated first and heated the increase in blood flow and vascular volume was generally greater than that caused by irradiation or heat alone for about 4 weeks postirradiation. The combined effects were either additive or more than additive depending on the interval between the irradiation and heating during this period. Hyperthermia at 40 days postirradiation increased the blood flow and vascular volume only slightly above that of the irradiated control, indicating that the combined effect of irradiation and hyperthermia became less than additive. It was concluded that the thermosensitivity of irradiated blood vessels in skin and muscle for 3-4 weeks postirradiation was at least similar or greater than that of unirradiated controls. The thermosensitivity of vessels appeared to decline 40 days after irradiation.

Animals↗
PubMed1982

Effect of hyperthermia on hypoxic cell fraction in tumor.

The effect of hyperthermia on the proportion of hypoxic cells in SCK mammary tumor of A/J mice was investigated. About 45% of clonogenic cells in the unheated control tumor were radiobiologically hypoxic. Upon heating with a 43.5 degree C water bath for 30 min, the proportion of hypoxic cells increased and then decreased: it was 95% at 5 hr and 60% at 12 and 24 hr after heating. Despite the increase in the proportion of hypoxic cells 5 hr after heating, the absolute number of hypoxic cells in the tumors at this time was significantly smaller than that in the unheated control tumors because of a decrease in the total number of surviving tumor cells. The initial increase in the proportion of hypoxic cells after heating may be attributed mainly to vascular occlusion. Proliferation of cells in the oxic area, and thus an increase in oxic cell number, appears to account for the decline in the proportion of hypoxic cells from 5 hr after heating.

Animals↗
PubMed1982

Mediastinal nonseminomatous germ cell tumors: the role of combined modality therapy.

Twelve male patients with mediastinal nonseminomatous germ cell tumors were treated with chemotherapy (with or without operation and radiation therapy) between 1963 and 1980. Eight patients, treated with only chemotherapy and radiotherapy, died with a median survival from diagnosis of 6 months (range, 3 to 12 months). The 4 survivors remain alive at 12, 15, 34, and 56 months from diagnosis; all are without evidence of disease. All surviving patients were treated with surgical resection of disease either before of after chemotherapy. A major problem in the management of mediastinal nonseminomatous germ cell tumors is the persistence of local disease, which may be overcome by vigorous cytoreductive intervention. Multicenter collaboration will be required to define the optimal combined-modality approach.

Adolescent↗
PubMed1982

Results of lung irradiation for Hodgkin's disease patient with large mediastinal masses and/or hilar disease.

From 1970 to 1979, 130 patients with Hodgkin's disease were seen at the University of Minnesota and were treated with curative radiotherapy following surgical staging. Thirty-nine of the 130 patients had large mediastinal masses. Twenty patients with large mediastinal masses treated before 1975 received regular mantle-field irradiation. Our treatment technique was modified in 1975 because of frequent recurrences in the intrathoracic region in these patients. Between 1975 and 1979, patients with large mediastinal masses were treated with low-dose lung irradiation as an initial part of the mantle field treatment. Nineteen patients were treated in this manner, and 16 of these 19 have been followed for greater than 24 months. Only one of the 16 patients has had a recurrence in the lung. We have not seen any serious acute of subacute pulmonary or cardiac complications after low-dose lung irradiation. The followup period is still too brief for the study of late complications. Analysis of four results with lung irradiation reveals excellent control of large mediastinal masses and significantly improved recurrence-free survival.

Adolescent↗
PubMed1982

Changes in thermosensitivity of mouse mammary carcinoma following hyperthermia in vivo.

The time course of change in thermosensitivity of SCK tumor cells in vivo was investigated following preheating at 43.5 degrees for 30 min. At varying times after the preheating with water bath, tumors were subjected to graded doses of second heating at 43.5 degrees in vivo, and cell survival was determined by using in vitro cloning method. Thermosensitivity of the tumor cells in vivo [duration of heating for exponential inactivation of cells to 1/e (Do): 15.5 min] gradually increased after the preheating, reaching a maximum increase at 5 hr (Do: 7.5 min), and then decreased thereafter, due probably to a development of thermotolerance. Maximum thermotolerance was observed at 12 hr after the preheating, leading to a 3-fold increase in Do (48 min). The thermotolerance gradually decayed for several days thereafter. The initial increase in thermosensitivity might be attributed to the acidic and nutritionally deprived intratumor environment as a result of vascular damage in heated tumor. It appears that thermotolerance gradually develops as time elapses and that it eventually overcomes the thermal sensitization of tumor cells in vivo.

Animals↗