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Biomedical subjects

I R McDougall

Publications and source records attributed to I R McDougall.

At least 19 recordsLinked to original sources
PubMed1992

The role of functional imaging in neoplasms of the thyroid.

Iodine-123 and Iodine-131 have suitable physical properties that enable them to be used for functional imaging of the thyroid. Iodine-123 is used for routine testing for hyperthyroidism and thyroid nodules, whereas I-131, which has a longer half-life, is used for whole body imaging for detecting metastatic thyroid cancer in patients who have undergone thyroidectomy. The radionuclides of iodine are trapped and organified like nonradioactive iodine. In contrast, technetium as pertechnetate is trapped by the thyroid and can be used for imaging immediately after intravenous injection. There can be differences in scintiscans made in the same patient using radioiodine vs. technetium. Thallium is a useful adjuvant imaging agent for thyroid cancer. It should be stressed that correlation with the clinical findings and biochemical thyroid function tests are very important when evaluating thyroid scintiscans.

Female↗
PubMed1991

Thyroid diseases after treatment of Hodgkin's disease.

BACKGROUND AND METHODS: Thyroid disease, especially hypothyroidism, is common in patients with Hodgkin's disease who have been treated with irradiation. We reviewed the records of 1787 patients (740 women and 1047 men) with Hodgkin's disease who were treated with radiation therapy alone (810 patients), radiation and chemotherapy (920 patients), or chemotherapy alone (57 patients) at Stanford University between 1961 and 1989. Among these patients, 1533 were alive at the last follow-up, and 254 had died of causes other than Hodgkin's disease. (Four other patients were excluded from the analysis because they had undergone thyroidectomy before treatment for Hodgkin's disease. The thyroid was irradiated in 1677 patients. Follow-up averaged 9.9 years. RESULTS: A total of 573 patients had clinical or biochemical evidence of thyroid disease. Among the 1677 patients whose thyroid was irradiated, the actuarial risk of thyroid disease 20 years after treatment was 52 percent, and it was 67 percent at 26 years. Hypothyroidism was found in 513 patients. A total of 486 patients received thyroxine therapy for elevated serum thyrotropin concentrations and either low free thyroxine (208 patients) or normal free thyroxine values (278 patients); 27 had transient elevations of the serum thyrotropin level that were not treated. Graves' hyperthyroidism developed in 30 patients (2 of whom had not undergone thyroid irradiation), and ophthalmopathy developed in 17 of these patients. Ophthalmopathy developed in four other patients with Graves' disease during a period of hypothyroidism (n = 3) or euthyroidism (n = 1). The risk of Graves' disease was 7.2 to 20.4 times that for normal subjects. Silent thyroiditis with thyrotoxicosis developed in six patients. Forty-four patients were found to have single or multiple thyroid nodules, 26 of whom underwent thyroidectomy. Six of the 44 had papillary or follicular cancers. Among the patients who did not undergo operation, 12 had small functioning nodules, 4 had cysts, and 2 had multinodular goiters. The actuarial risk of thyroid cancer was 1.7 percent. The risk of thyroid cancer was 15.6 times the expected risk. CONCLUSIONS: High risks of thyroid disease persist more than 25 years after patients have received radiation therapy for Hodgkin's disease, reinforcing the need for continued clinical and biochemical evaluation. Prolonged follow-up confirms an elevated risk of thyroid cancer and Graves' disease as well as hypothyroidism in these patients.

Adolescent↗
PubMed1991

Graves' disease. Current concepts.

Graves' disease is an organ-specific autoimmune disorder. There is no universal agreement on the mechanism of Graves' disease, but the over-activity of the thyroid is due to an antibody capable of attaching to and activating the TSH receptor of follicular cells. There are other extrathyroidal features that are not caused either by this antibody or by hyperthyroidism. The clinical diagnosis is generally straightforward and can be confirmed by in vitro measurement of thyroid hormones and TSH. A measurement of radioiodine uptake is also valuable. Treatment is not specific for the immunologic defect, but its purpose is to lower the thyroid hormone levels to normal. This can be achieved with antithyroid medication, radioiodine iodine-131, or thyroidectomy. In most clinical situations, a strong argument can be made for iodine-131 therapy, which is safe and definitive, although posttreatment hypothyroidism and the need for lifelong thyroxine are to be expected.

Graves Disease↗
PubMed1991

A technique for intraoperative bone scintigraphy. A report of 17 cases.

Since 1981, intraoperative bone scanning has been used at Stanford University Hospital to assist in the localization and excision of skeletal lesions in the surgical suite. The utility of bone scans to detect lesions not otherwise "visible" is valuable in guiding the surgeon to the pathological site. In addition, intraoperative scanning can define the exact amount of tissue to be excised, averting excessive surgery near joints or along weight-bearing bones. Seventeen cases are presented.

Adult↗
PubMed1991

Papillary cancer in a patient treated with radioiodine for Graves' hyperthyroidism. Case report and a review of the risk.

A small encapsulated papillary thyroid cancer was found in a patient who had received I-131 therapy for Graves' disease 31 months previously. The relationship of Graves' hyperthyroidism and thyroid cancer is discussed, as well as the possible role of I-131 as a cause of the cancer. The published data do not support I-131 as an etiology. The patient is clinically well and cured of both hyperthyroidism and the cancer.

Adult↗
PubMed1991

Roles of thrombin and platelet membrane glycoprotein IIb/IIIa in platelet-subendothelial deposition after angioplasty in an ex vivo whole artery model.

BACKGROUND: Platelet deposition at the site of injury caused by balloon angioplasty is associated with acute closure and restenosis. METHODS AND RESULTS: In a new ex vivo whole artery angioplasty model, we examined the roles of thrombin inhibition with D-Phe-Pro-ArgCH2Cl (PPACK) and inhibition of the platelet membrane fibrinogen receptor glycoprotein IIb/IIIa (GPIIb/IIIa) with monoclonal antibody 7E3 on platelet deposition at the site of balloon injury. Fresh rabbit aortas were mounted in a perfusion chamber. One half of the mounted arterial segment was dilated with a standard angioplasty balloon catheter and the uninjured half served as the control segment. The vessels were perfused with human blood at physiological pressure and shear rates of 180-250 second-1 for 30 minutes. Platelet deposition was measured using 111In-labeled platelets and scanning electron microscopy. With heparin (2 units/ml) anticoagulation, 8.2 +/- 2.2 x 10(6) platelets/cm2 were deposited at the site of balloon injury compared with 0.7 +/- 0.2 x 10(6) platelets/cm2 on uninjured segments (p less than 0.02, n = 7). PPACK was tested at a concentration (10 microM) that totally inhibited platelet aggregation in response to thrombin. 7E3 was tested at a concentration (10 micrograms/ml) that totally inhibited platelet aggregation. Platelet deposition at the site of balloon injury was reduced 47% by PPACK and 70% by 7E3 compared with heparin. CONCLUSIONS: At shear rates seen in nonstenotic coronary arteries, PPACK and 7E3 are more effective than heparin in reducing platelet deposition at the site of balloon injury. The significant inhibition of platelet deposition by PPACK demonstrates the importance of heparin-resistant thrombin in platelet thrombus formation. The 7E3 results suggest that approximately 70% of platelet deposition at the site of balloon injury is GPIIb/IIIa dependent and that the remaining 30% results from non-GPIIb/IIIa-mediated platelet-subendothelial adhesion. Finally, the ex vivo whole artery system is a useful model for studying platelet-vessel wall interactions under physiologically defined parameters.

Amino Acid Chloromethyl Ketones↗
PubMed1991

Utilization of bone scans in conjunction with prostate-specific antigen levels in the surveillance for recurrence of adenocarcinoma after radical prostatectomy.

Follow-up evaluation of patients who have undergone radical prostatectomy routinely consists of serial bone scintigraphy and, more recently, prostate-specific antigen (PSA) levels. The utility of serial bone scans in combination with PSA levels is retrospectively reviewed in 118 men treated by radical prostatectomy for clinical Stage A or B disease who, at the time of surgery, had no evidence of metastatic disease. Of the 118 patients, 75.4% had no abnormality on either test (mean follow-up 32.4 mo), 9.3% demonstrated a detectable or rising PSA level with negative bone scan (mean follow-up 35 mo), and 8.5% exhibited a detectable and or rising PSA level and positive bone scan (mean follow-up 30.7 mo). Follow-up bone scans were read as either positive or indeterminate with undetectable PSA levels in 6.8% of patients (mean follow-up 27.3 mo). Critical review of the equivocal studies suggests that postoperative PSA levels more truly represent the clinical situation than bone scans. Following radical prostatectomy, routine bone scintigraphy provides little additional information when PSA levels are negative. If PSA becomes detectable or the patient develops symptoms, bone scintigraphy should then be performed.

Adenocarcinoma↗
PubMed1991

Letter from America.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Kinetics of leukocyte sequestration in the lungs of acutely septic primates: a study using 111In-labeled autologous leukocytes.

To further clarify the role of leukocytes in the pathogenesis of ARDS, we studied the localization and kinetics of leukocyte migration using 111In-labeled autologous white cell scans (111In wbc scans) in four primates made acutely septic with infusions of Escherichia coli. Whole body images were obtained with a gamma camera and were acquired on computer every 15 min beginning immediately after the E. coli infusion. Simultaneous measurements of C5a and peripheral blood leukocyte count were also obtained. Within 5 min of initiating sepsis, three major events occurred: complement activation as measured by the production of C5a, a profound fall in peripheral leukocyte count, and a significant increase in the sequestration of leukocytes in the lungs. The pulmonary sequestration reached a peak at 15 min with a mean of 152% of baseline activity. This sequestration consisted of a population that was predominantly neutrophils. Damage to the pulmonary capillary endothelium was demonstrated by an increase in extravascular lung water. The results support a role for neutrophils and complement as mediators in the pathogenesis of ARDS.

Acute Disease↗
PubMed1990

Prognostic factors in the radiotherapy of Graves' ophthalmopathy.

Between April 1968 and February 1988, 311 patients with symptomatic and progressive Graves' ophthalmopathy were treated with megavoltage orbital radiotherapy. The patients were divided into three groups: I (156 patients) treated with 20 Gy/2 weeks; II (69 patients) treated with 30 Gy/3 weeks, and III (a most recent set of 86 patients) received 20 Gy/2 weeks. The degree of eye involvement was evaluated numerically before and after therapy for each of five parameters: soft tissue signs, proptosis, eye muscle impairment, corneal involvement, and sight loss. Pre-treatment and current thyroid diagnosis and status were also noted. To evaluate the effects of radiotherapy alone, follow-up was terminated at the time any eye surgery was done; for those not treated surgically the minimum follow-up was 12 months. Because there were significant demographic differences between the patient groups, the results of each group were analyzed separately. A stepwise linear regression analysis was performed to determine if there were any significant variables affecting outcome. Based on these data formulae were derived which enable outcome to be predicted in any patient. Before therapy more than 90% of patients in all groups had soft tissue and eye muscle involvement, whereas 65-75% had proptosis and about half 50% had some degree of sight loss. Radiotherapy arrested progression of ophthalmic parameters in all but 1-6% of the patients. Objective and symptomatic improvement was noted for all parameters assessed, but there was marked individual variability. The best responses were noted for soft tissue, corneal involvement, and sight loss; however over half the patients had some improvement in eye muscle function and proptosis. Factors which resulted in less favorable outcome included male gender, advanced age, need for concurrent therapy for hyperthyroidism, and no history of hyperthyroidism. No complications have been observed. No significant differences in outcome were observed between the two dosage schedules. Following radiotherapy 29% of patients subsequently underwent some form of eye surgery, mostly eye muscle surgery to correct diplopia. After radiotherapy corticosteroid therapy was stopped without relapse in 76%. Orbital radiotherapy can result in improvement in signs and symptoms of Graves' ophthalmopathy in the majority of patients. For the remainder of patients the disease manifestations can be stabilized to allow functional surgical correction.

Connective Tissue↗