Biomedical subjects
Publications and source records attributed to I M Jackson.
Using immunofluorescent techniques thyrotropin releasing hormone (TRH) is demonstrated in skin of Rana pipiens and R. catesbeiana. The immunofluorescent-TRH is localized in all cell layers of the epidermis and in the epithelium lining the various cutaneous glands, but not in the dermal layer.
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An androgen-secreting tumor of the left ovary was preoperatively localized in a 55-year-old virilized woman by radioimmunoassay of blood androgens. The blood sample was obtained by bilateral catheterization of the ovarian and adrenal veins using a percutaneous retrograde femoral approach. A total abdominal hysterectomy and bilateral salpingo-oophorectomy were performed, and revealed a lipoid cell tumor of the left ovary and right ovarian stromal hyperplasia. Despite early postoperative return of plasma adrogens to the normal range, virilizing signs persisted almost unchanged 1 year after surgery.
The prevalence of serum thyroid-stimulating immunoglobulins (T.S.I.) in a variety of thyroid diseases was determined in 96 patients and 35 normal controls. Significantly elevated levels of T.S.I. were found not only in patients with Graves' disease and Hashimoto's thyroiditis but also in those with non-toxic and toxic multinodular goitre, whereas patients with a single autonomously functioning thyroid nodule, with subacute thyroiditis, and with "hyperthyroiditis" had levels which did not differ from those in the controls. We postulate that non-toxic multinodular goitre, like Graves' disease, may result from increased circulating T.S.I., which in some cases may be present in sufficient concentration to cause thyrotoxicosis.
A 63-year-old woman with longstanding spastic paraplegia and neurological evidence of long tract disturbance was found to have hypothyroidism, partial diabetes insipidus, hyperprolactinemia, and gonadotropin deficiency of hypothalamic origin. Replacement therapy with thyroxine and prednisone induced complete remission of the neurological abnormalities. The association of spastic paraplegia with hypothalamic insufficiency has not been reported previously. The possibility of hypothalamic disease should be considered in cases of spastic paraplegia of unknown cause.
The effect on thyroid status of changing from thyroid USP to sodium L-thyroxine was evaluated in 40 patients. With thyroid, abnormally high triiodothyronine (T3) levels were seen in 36 of 38 patients receiving doses of 90 to 240 mg; compared to sodium L-thyroxine, 0.15 to 0.2 mg, the serum T3 was higher (289 +/- 15 ng/dl versus 176 +/- 9 ng/dl, p less than 0.0005) and the thyroxine (T4) lower (7.4 +/- 0.3 microgram/dl versus 11.6 +/- 0.5 microgram/dl, P less than 0.01). Thyrotoxic symptoms occurred in six patients and diminished or disappeared after the change to sodium L-thyroxine, suggesting that the raised T3 level with thyroid may have undesirable effects in some patients. The T4 level, because it is low whether symptoms are present or not, may inadvertently suggest the need for higher dosage of desiccated thyroid in patients who have already received adequate replacement. The dose of sodium L-thyroxine was adequately assessed by measurement of both T4 and T3 levels. Thyroid USP should be discontinued as thyroid medication since it produces thyroid hormone levels that are misleading estimates of thyroid function and can cause thyrotoxic symptoms.
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In order to evaluate the role of leuteinizing hormone releasing hormone (LHRH) and gonadotropins in the control of secretion of Müllerian inhibiting substance, groups of pregnant rats were injected intraperitoneally with high potency antiserum from a rabbit immunized with LHRH. Pregnant females were injected at 13 and 20 days of gestation with LHRH antiserum or an equal volume of normal rabbit serum as a control. The testes and penis were reduced in weight and size in 6-day-old pups of the experimental group indicating the luteinizing hormone (LH) was blocked and that LHRH antiserum was active. Testicular fragments of 17-day fetuses and 6-day-old pups showed an increase relative to controls in Müllerian inhibiting substance activity in a graded organ culture bioassay system. These studies suggest that secretion of Müllerian inhibiting substances is curtailed by one or both gonadotropins.
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The therapeutic management of hypothyroidism caused by deficient thyroid hormone production is discussed. The therapeutic use of the following thyroid agents is reviewed: levothyroxine sodium, Thyroid USP, thyroglobulin, liotrix, and liothyronine sodium. Myxedema coma, neonatal hypothyroidism, primary hypothyroidism, and secondary and tertiary hypothyroidism are specific hypothyroid states for which drug therapy is discussed. Levothyroxine sodium is the preferred agent because of consistent potency, restoration of normal, constant serum levels of thyroxine (T4) and triiodothyronine (T3) and ease of interpretation of thyroid hormone levels. Other agents, because they contain T3, result in postabsorptive elevated T3 serum concentrations that may cause thyrotoxic symptoms and reduction of T4 levels. This, in turn, may give rise to misleading estimates of thyroid dosage. Patients with the sick euthyroid or low T3 syndromes are not candidates for thyroid hormone therapy.
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Thyrotropin-releasing hormone, a hypothalamic tripeptide that stimulates the secretion of pituitary thyroid-stimulating hormone in mammalian species and is widely distributed throughout the brain of vertebrates, is present in the skin of the frog (Rana pipiens) in concentrations twice that found in the hypothalamus of this amphibian. A skin extract shows biologic activity appropriate to its immunoreactive content. Apart from the brain and spinal cord, immunoreactive thyrotropin-releasing hormone is found only in the blood and retina in significant concentrations. The results imply that frog skin is a huge endocrine organ that synthesizes and secretes this hormone.
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