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Biomedical subjects

F Clark

Publications and source records attributed to F Clark.

At least 37 records · Page 2Linked to original sources
PubMed1986

Association between thyroid microsomal antibodies of subclass IgG-1 and hypothyroidism in autoimmune postpartum thyroiditis.

The potential role of thyroid microsomal (Mic) antibodies in the development of postpartum hypothyroidism was investigated in 34 euthyroid women, whose sera were found to contain Mic antibodies in pregnancy. Additional serum samples were obtained 2. 5 and 10-12 months after delivery and analysed for IgG class and IgG subclass levels of Mic antibodies by ELISA techniques. Characteristically, Mic antibodies decreased from early pregnancy to 2 months postpartum, increased two-fold 5 months postpartum and had returned 10-12 months postpartum to the early pregnancy level. Mic antibodies were predominantly subclass IgG-1 or IgG-4 with only minor contributions from IgG-2 and IgG-3. In each individual the percentage contribution made by each IgG subclass to Mic antibody was essentially similar in early pregnancy and the postpartum period despite changes in total IgG class Mic antibody. During the year following delivery, thyrotoxicosis alone (Graves' disease) developed in 5 women. In the remaining 29 patients the absolute levels of Mic antibodies of IgG-4 subclass were similar 5 months postpartum in women with maximal serum thyrotropin (TSH) greater than 20 mU/1 (mean optical density in ELISA +/- s.d.; 0.84 +/- 0.538; n = 13) and in women with maximal TSH less than 10 mU/l (0.69 +/- 0.457; n = 16). In contrast, significantly higher values were observed for Mic antibody of IgG-1 subclass in patients with TSH greater than 20 mU/l (1.14 +/- 0.440) compared with women with maximal TSH less than 10 mU/l (0.65 +/- 0.289) (P less than 0.001 by t-test for groups). These results imply that the magnitude of Mic antibody levels of subclass IgG-1 but not IgG-4 is associated with the development of postpartum hypothyroidism and possibly with tissue destruction in autoimmune thyroid disease in general.

Adult↗
PubMed1986

Subpopulations of thyroid autoantibody secreting lymphocytes in Graves' and Hashimoto thyroid glands.

Lymphocytes isolated from Graves' and Hashimoto thyroid tissue by enzymatic (dispase) digestion or mechanical disaggregation were markedly different in terms of their ability to synthesize thyroid autoantibodies in culture. Dispase digestion, followed by removal of thyroid follicular cells, gave a lymphocyte population with a high T:B cell ratio (6:1). However, the ability of these cell suspensions to synthesize microsomal (Mic) and thyroglobulin (Tg) antibodies spontaneously was significantly increased compared with lymphoid suspensions isolated by mechanical means. Spontaneous synthesis of thyroid autoantibodies was not markedly enhanced in cell suspensions prepared from patients' lymph node tissue by digestion compared with mechanical disaggregation. Further, Mic and Tg antibody production by thyroid lymphocytes prepared using dispase was inhibited by pokeweed mitogen (PWM) whereas in most cases suspensions prepared from the same tissues by mechanical dispersion synthesized low or undetectable levels of autoantibodies whether PWM was present or absent. Digestion of tissue debris remaining after mechanical removal of lymphocytes gave suspensions which had an increased proportion of suppressor/cytotoxic T cells compared with suspensions produced mechanically or by digestion alone; however, in terms of spontaneous autoantibody synthesis and PWM induced inhibition, these suspensions were similar to these obtained by digestion alone. It would therefore seem that enzymatic digestion of thyroid tissue resulted in the isolation of a lymphoid population which was different from that extracted by mechanical disaggregation. The digestion process appears to permit the recovery of lymphocytes closely associated with thyroid follicular cells and our studies suggest that it is this population which makes the major contribution to autoantibody synthesis.

Adult↗
PubMed1985

The effect of carbimazole on thyroid autoantibody synthesis by thyroid lymphocytes.

Thyroid autoantibody synthesis was investigated in cultures of lymphocytes isolated from several sources, including thyroid and lymph nodes from patients with hyperthyroid Graves' disease treated preoperatively with carbimazole or propranolol. The ability of thyroid lymphocytes to secrete immunoglobulins, including thyroid microsomal or thyroglobulin autoantibodies, was markedly reduced in lymphocyte suspensions obtained from patients treated with carbimazole compared with suspensions from patients treated with propranolol. This effect (which was greater in individuals treated with carbimazole for longer periods) was attributable to a significant reduction in the number of viable lymphocytes present after the 14-day culture interval. In contrast, the type of preoperative therapy had little effect on cultures of lymphocytes obtained from lymph nodes draining the thyroid. Although it is not yet clear whether carbimazole exerts its effects in vivo by direct immunosuppression or indirectly by altering the thyroid microenvironment, our observations indicate that the fall in serum levels of thyroid autoantibodies that occurs during carbimazole therapy is related to an effect of the drug on lymphocytes within the thyroid.

Antibody Formation↗
PubMed1985

Insulin secretion, adipocyte insulin binding and insulin sensitivity in thyrotoxicosis.

The pattern of insulin secretion following an oral glucose load and the insulin receptor status and insulin sensitivity of adipocytes have been studied in patients with thyrotoxicosis and in matched controls. Thyrotoxic subjects showed normal basal and peak levels of serum immunoreactive insulin (peak, 69.0 +/- 6.8 vs 54.3 +/- 8.8 mU/l) and serum C-peptide (peak, 1.95 +/- 0.13 vs 1.71 +/- 0.12 nmol/l for thyrotoxic and control subjects, respectively). Peak serum proinsulin was higher in the thyrotoxic group (64.8 +/- 7.3 vs 39.0 +/- 3.7 pmol/l; P less than 0.01). Maximum specific insulin binding to adipocytes was decreased in the thyrotoxic group (1.80 +/- 0.18 vs 2.62 +/- 0.27%; P less than 0.025) and half-maximum displacement of tracer insulin was similar in the two groups, suggesting that reduced receptor number rather than reduced affinity accounted for the difference. However, adipocyte insulin sensitivity was normal as judged by half-maximal stimulation values of 13.9 +/- 3.6 vs 11.4 +/- 2.1 pmol/l, respectively for lipogenesis and 24.3 +/- 2.2 vs 24.6 +/- 3.6 pmol/l, respectively for glucose transport. Hence, thyroid hormone excess appears to affect adipocyte insulin receptor number directly, but change in receptor number is not associated with change in adipocyte insulin sensitivity in hyperthyroidism. The normal insulin secretion together with the failure to demonstrate abnormal insulin sensitivity of one of the major peripheral tissues suggests that disturbed hepatic rather than peripheral insulin responsiveness may be responsible for the glucose intolerance of hyperthyroidism.

Adipose Tissue↗
PubMed1985

A comparison of impact of undergraduate and graduate occupational therapy education on professional productivity.

This article presents an account of the evolutionary changes in occupational therapy graduate education at the University of Southern California (USC) in response to the increasing professional demands and the expanding knowledge base of the field. The contention that undergraduate and graduate education represented by these changes would result in different student products was tested. A questionnaire survey was used to assess the responses of 189 former undergraduate and graduate occupational therapy students of USC on issues relating to professionalism, leadership, attitudes, and scholarly contributions. Results of this study support the theory that graduate education of a specific kind and quality enhances the professionalization of occupational therapy more so than does undergraduate education.

Adult↗
PubMed1985

Functional analysis of T and B cells from blood and thyroid tissue in Hashimoto's disease.

B lymphocytes from Hashimoto blood and thyroid tissue have been cultured with autologous T cells from thyroid/blood to assess their ability to synthesise IgG and thyroid autoantibody. Thyroid B cells were able to synthesize microsomal antibody spontaneously in the absence of T cells or pokeweed mitogen (PWM) and this synthesis was increased in the presence of thyroid T cells without PWM or with blood T cells with PWM. In contrast, blood B cells did not secrete thyroid autoantibody spontaneously but could be induced to do so by thyroid T cells spontaneously or by blood T cells with PWM. Despite these differences, lymphocytes from blood and thyroid tissue secreted microsomal or thyroglobulin antibodies in culture which were similar in terms of the IgG subclass distribution. It would appear, therefore, that although the state of activation of B and T cells is different in blood and thyroid tissue, the precursors of thyroid autoantibody secreting cells are the same.

Autoantibodies↗
PubMed1979

Survival associated with hepatorenal syndrome.

We have described an advanced case of type A2 hepatorenal syndrome with subsequent recovery. The renal failure in this syndrome is secondary to the hepatic failure. In this patient, renal support was afforded by peritoneal dialysis, while hepatic recovery was facilitated by takedown of a jejunoileal shunt and by intravenous hyperalimentation. As liver function returned toward the normal range, renal function improved. Reversal of hepatic dysfunction is critical for reversal of hepatorenal syndrome of the type A2 variety.

Acute Kidney Injury↗
PubMed1979

Thyroglobulin and microsomal autoantibody production by cultures of Hashimoto peripheral blood lymphocytes.

Peripheral blood lymphocytes from patients with Hashimoto's thyroiditis have been cultured for 2--3 weeks in Marbrook flasks. During this period, readily detectable amounts of thyroglobulin and microsomal antibodies were synthesized by the cells and secreted into the culture medium. Gel filtration studies indicated that the autoantibodies produced in culture were of a similar molceular weight to the serum antibodies and this provided evidence that autoantibody synthesis in vitro was representative of autoantibody synthesis in vivo. Our data suggest that this culture technique may be used to make a detailed investigation of the human autoimmune disease process.

Adult↗
PubMed1978

Thyroid hormone concentrations in a large scale community survey. Effect of age, sex, illness and medication.

Total thyroid hormone concentrations have been measured in the course of a large scale community survey to determine the distribution of these variables in the normal population and to assess the effect of age, sex, previously undectected thyroid disease and medication upon these parameters. 2779 subjects were studied. Serum T4 concentrations were normally distributed. A progressive increase in T4 levels with age was noted in the males, and a smaller increase in females which was concealed by the raised T4 values secondary to oral contraceptive therapy in females under the age of 45. Serum T3 levels were also normally distributed. There was a small reduction in T3 with age in the males but this fall was not seen in the females. T3 values were relatively higher in females under the age of 45 but this increase was not noted after exclusion of subjects taking an oral contraceptive. The changes in thyroid hormone concentrations with age are relatively minor (particularly with respect to T3) in a randomly selected sample from an English town. It is suggested that the changes reported by other authors reflect the process of selection used, and the high frequency of undetected thyroid disease, other illness and medication in hospital-based communities.

Adolescent↗
PubMed1977

Value of thyroid-stimulating-antibody determinations in predicting short-term thyrotoxic relapse in Graves' disease.

Thirty consecutive patients with hyperthyroid Graves' disease received a 6-month course of antithyroid drugs. Sixteen patients relapsed within 6 months of the withdrawal of antithyroid therapy. All patients with high levels of thyroid-stimulating antibodies (TSAb) at the time of drug withdrawal relapsed within 2 months of discontinuing the antithyroid treatment while all patients with low or undetectable TSAb activity at the time of drug withdrawal remained in remission. It was not possible to predict the disease course in patients who had intermediate levels of TSAb when antithyroid therapy was stopped.

Adult↗
PubMed1977

Immunoreactive beta-melanocyte-stimulating hormone in cerebrospinal fluid and plasma in hypopituitarism: evidence for an extrapituitary origin.

Immunoreactive beta-melanocyte-stimulating hormone (beta-MSH) was measured in the plasma of 19 patients with hypopituitarism and in the cerebrospinal fluid (CSF) of five of these patients. In neither plasma nor CSF were the beta-MSH concentrations significantly different from those in normal controls. These observations raise the possibility that beta-MSH may be produced by and secreted from neural tissue; this is supported by the findings of beta-MSH in high concentrations in many parts of the brain.

Brain Chemistry↗