Experimental myocardial infarction. 8. Chronotropic augmentation of cardiac function in left ventricular failure of acute and healing stages in intact conscious dogs.

The hemodynamic effects of tachycardia induced by atrial pacing were investigated in left ventricular failure of acute and healing experimental myocardial infarction in 20 intact, conscious dogs. Myocardial infarction was produced by gradual inflation of a balloon cuff device implanted around the left anterior descending coronary artery 10-15 days prior to the study. 1 hr after acute myocardial infarction, atrial pacing at a rate of 180 beats/min decreased left ventricular end-diastolic pressure from 19 to 8 mm Hg and left atrial pressure from 17 to 12 mm Hg, without change in cardiac output. In the healing phase of myocardial infarction 1 wk later, atrial pacing decreased left ventricular end-diastolic pressure from 17 to 9 mm Hg and increased the cardiac output by 37%. This was accompanied by evidence of peripheral vasodilation. In two dogs with healing anterior wall myocardial infarction, left ventricular failure was enhanced by partial occlusion of the circumflex coronary artery. Both the dogs developed pulmonary edema. Pacing improved left ventricular performance and relieved pulmonary edema in both animals. In six animals propranolol was given after acute infarction, and left ventricular function deteriorated further. However the pacing-induced augmentation of cardiac function was unaltered and, hence, is not mediated by sympathetics.The results show that the spontaneous heart rate in left ventricular failure of experimental canine myocardial infarction may be less than optimal and that maximal cardiac function may be achieved at higher heart rates.

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.

Human monoclonal thyroglobulin autoantibodies of high affinity. I. Production, characterisation and interaction with murine monoclonal thyroglobulin antibodies.

Four hybridomas secreting human thyroglobulin (Tg) autoantibodies of different IgG subclasses and light chain types (IgG1 lambda, IgG1 kappa, IgG2 lambda and IgG2 kappa) were obtained by direct fusion of Hashimoto thyroid lymphocytes with the mouse myeloma X63-Ag.653. The autoantibodies were specific for human Tg and the functional affinities were high (only 2.6-3.9 log10 pM Tg required to give 50% inhibition of binding in ELISA). Using thyroid lymphocytes, 4 lines secreting Tg autoantibodies were obtained from 11 fusions compared with 1 line from 32 fusions of Epstein Barr virus infected blood lymphocytes, which emphasises the importance of using lymphocytes derived from a tissue known to be enriched in thyroid autoantibody secreting precursor B cells. These 4 human Tg autoantibodies, as well as an IgG2 lambda Tg antibody previously derived from Hashimoto blood B cells and an IgG4 kappa monoclonal Tg antibody present in a Hashimoto serum, were used in attempts to probe the interaction between human Tg autoantibodies and the Tg molecule (2 polypeptides of 330 KD). The binding to 125-I Tg by 3/7 murine monoclonal antibodies was inhibited (36-78%) by an IgG2 lambda and an IgG4 kappa human monoclonal Tg autoantibody, indicating an overlap between the epitopes recognised by these 3 murine monoclonal Tg antibodies and 2 monoclonal human Tg autoantibodies. None of the human Tg autoantibodies (or the murine monoclonal Tg antibodies) bound to Tg denatured by reduction and alkylation. Although the number of observations is limited, our study demonstrates that high affinity human monoclonal Tg autoantibodies, like polyclonal serum Tg autoantibodies, recognise non-linear B cell epitopes on conformationally intact human Tg.

Production and characterisation of a human monoclonal thyroid peroxidase autoantibody.

A human-mouse hybridoma has been produced by fusion of Hashimoto thyroid lymphocytes with the mouse myeloma line X63-Ag8.653. The cloned hybridoma secreted 2.5 micrograms per 10(6) cells per day of an IgG kappa thyroid peroxidase (TPO) autoantibody (2G4) with high affinity (2.5 x 10(9) molar-1) and specificity for human TPO. 2G4 did not react with lactoperoxidase, horseradish peroxidase or human myeloperoxidase or with porcine TPO or with human thyroglobulin. Plastic tubes coated with 2G4 bound about 50% of 125I-labelled human TPO added and the binding was inhibited by IgGs prepared from 18/18 TPO autoantibody-positive sera. This indicated that all 18 sera contained autoantibodies which recognised the same (or closely related) epitope as 2G4. Plastic tubes coated with IgGs from different TPO autoantibody-positive patient sera also bound 125I-labelled TPO but inhibition by 2G4 in this system was not complete. This suggested that the sera contained at least 2 types of TPO autoantibodies, with only one type of autoantibody reactive with the same epitope as 2G4.

A prospective study of thyroid ultrasound scan in the clinically solitary thyroid nodule.

Thyroid ultrasound differentiates solid from cystic lesions, solitary nodules from multinodular and diffuse enlargement, and extrathyroidal lesions. Two hundred consecutive patients with a clinically solitary thyroid nodule were investigated by ultrasound examination, thyroid function test, and thyroid auto-antibodies. Patients with confirmed solitary solid, or mixed solid and cystic nodules underwent surgery as well as those with cysts, multinodular or diffuse goitres with pressure symptoms, recurrent haemorrhage or relapsing hyperthyroidism. Comparison between the ultrasound and ultimate pathological findings in the 101 patients who underwent surgery showed that they were in agreement in 96 cases. The remaining 99 patients with cystic, multinodular or diffuse lesions have been followed up for a mean of two years. Nearly 50% of patients with a clinically solitary thyroid nodule have avoided surgery.

Non-Hodgkin's lymphoma of the thyroid: a retrospective review of all patients diagnosed in Nottinghamshire from 1973 to 1992.

The pathological and clinical features were reviewed of all primary non-Hodgkin's lymphomas (NHL) of the thyroid gland diagnosed between 1973 and 1992 in the population (1.1 million) served by the Nottingham and North Nottinghamshire Health Authorities. Of the 43 patients with histologically proven NHL, three had low grade mucosa associated lymphoid tissue (MALT) lymphomas (Stage IEA, 2; Stage IIEA, 1), 35 had intermediate or high grade lymphomas, Stage IEA or IIEA (intermediate MALT, 2; high grade MALT, 14; B-cell diffuse centroblastic, 17; anaplastic large cell (Ki-1) of null cell type, 1; high grade unclassifiable, 1), and one had unclassifiable NHL Stage IIEA. One patient had Stage IIIEA disease (high grade MALT) and three had stage IVA disease (high grade MALT, 2; B-cell diffuse centroblastic, 1). The median age was 68 years (range 45-86) with a female: male ratio of 6:1. For the 35 patients with intermediate or high grade thyroid NHL (Stages IEA and IIEA) the 5- and 10-year cause specific survival was 60%. The 21 patients treated between 1985 and 1992 initially with chemotherapy (except stage IEA (< 5 cm diameter) had a 5-year cause specific survival of 69% (95% CI 48-90) compared with 46% (95% CI 19-73) for the 14 patients treated between 1973 and 1984 with initial radiotherapy (Chi 2 = 1.62). The survival of those patients with intermediate or high grade MALT lymphomas was not significantly greater than of those patients with B-cell diffuse centroblastic NHL.

Diagnostic approaches to parotid swellings.

Although the mainstay assessment of parotid swellings remains clinical examination, cytology, computed tomography and magnetic resonance imaging may give valuable preoperative information on both the likely histology and the location of the individual swelling. This is important for therapeutic and prognostic reasons.

Prediction of hypothyroidism after partial thyroidectomy for thyrotoxicosis.

Hypothyroidism is one of the major complications after thyroidectomy for thyrotoxicosis, but the factors responsible are not well defined. In an attempt to define these factors 278 patients operated on in 1965-9 were studied in detail. The overall incidence of hypothyroidism was 49%. The high incidence of hypothyroidism during 1965-6 led to a policy of leaving larger remnants in the later years of the study, and it became apparent that the most important aetiological factor in postoperative hypothyroidism was small remnant size. There seemed to be an association between the incidence of hypothyroidism and the presence of antithyroglobulin antibodies, but this association was not statistically significant. The data suggested that blood group O might be more common and blood group A less common in hypothyroid patients. The incidence of hypothyroidism seemed to be uninfluenced by the age or sex of the patient, the size of the gland, or the amount and duration of preoperative antithyroid drug therapy.Though a reasonable prediction of the incidence of hypothyroidism can be made for a group of patients on the basis of remnant size, the fate of the individual can be predicted only within very wide limits. An indication of the future status of the individual patient at one year and subsequently does, however, seem possible from serum protein-bound iodine estimations at one and four months after operation. Hypothyroidism developing later than one year after operation has not been observed in this series. The ability to assess thyroid status early after surgery is of some merit in the long-term supervision of the postoperative thyrotoxic patient, and in this respect surgical treatment seems to have some advantage over radioiodine therapy.

Mediastinal parathyroid adenoma: a new method of localization.

201Tl-thallous chloride/99mTc sodium pertechnetate subtraction scanning is a simple and accurate means to demonstrate enlarged parathyroid glands. We report a case in which the intra-operative location of a mediastinal adenoma was greatly facilitated by using a probe radiation detector following intravenous injection of 201Tl-thallous chloride. We believe this is the first reported use of this technique in parathyroid surgery.

Propranolol in the surgical management of thyrotoxicosis.

Forty-nine thyrotoxic patients prepared for partial thyroidectomy with the beta-adrenoceptor blocking drug, propranolol, and iodine are compared with 42 patients prepared with carbimazole and iodine. The age and sex distribution of the two groups were comparable, but patients with obstructive airways disease and possible cardiac insufficiency were excluded from preparation with propranolol. The mean duration of preoperative treatment with propranolol was 40 days, compared with 89 days for carbimazole. Propranolol treated patients had lower pulse rates before and after operation. The serum PB(127)I values immediately before and after operation were higher in the propranolol group than in the carbimazole group, but were the same in both groups one and four months after operation. The incidence of hypothyroidism at one year after operation was 30% in the carbimazole prepared patients and 31% in the propranolol patients. Serum calcium levels were higher in the propranolol group at the time of operation. No adverse effects from the use of propranolol and at operation the thyroid gland prepared with propranolol was firmer, less friable, more easily mobilised and less likely to bleed than the gland prepared with carbimazole. There is, consequently, less risk of damage to the parathyroid glands and recurrent laryngeal nerves. However, the basal metabolic rate remains high on propranolol therapy and very careful supervision is advised.

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.

TSH receptor antibody synthesis by thyroid lymphocytes.

Several indirect observations have indicated that lymphocyte in the thyroid may be an important site of TSH receptor antibody synthesis in Graves' disease and we now describe an investigation of this possibility using improved lymphocyte isolation and TSH receptor antibody assay procedures. Our studies demonstrate that thyroid lymphocytes spontaneously produce TSH receptor antibody in culture. Furthermore, experiments with mitogen tend to suggest that these cells, in contrast to lymphocytes from lymph nodes draining the thyroid, are part of an active immune response to the TSH receptor.

Severe combined immunodeficient (SCID) mice: a model for investigating human thyroid autoantibody synthesis.

We have studied the ability of lymphocytes from the blood, thyroid and lymph nodes of patients with autoimmune thyroid disease (AITD) to produce autoantibodies to thyroglobulin (Tg) and/or thyroid peroxidase (TPO) in SCID mice. Human IgG class Tg and/or TPO antibodies were detectable in plasma from SCID mice 7 days after transfer of 15-25 x 10(6) cells/mouse and the highest levels were recorded 2-3 weeks later. In contrast, Tg and/or TPO antibodies were undetectable in recipients of lymphocytes from thyroid antibody negative controls. AITD thyroid lymphocytes produced the most antibody in recipient mice and lower levels were observed in recipients of AITD blood and lymph node lymphocytes. The amounts of Tg and/or TPO antibody detected were in accordance with the ability of thyroid and lymph node lymphocytes to secrete these autoantibodies spontaneously in culture (indicating the presence of cells activated in the patient) and with the capacity of blood lymphocytes (probably B memory cells) to secrete Tg and/or TPO antibodies in culture in response to pokeweed mitogen. Tg antibodies in plasma from SCID recipients of thyroid lymphocytes were of subclasses IgG1, IgG2 and IgG4 and the proportions closely resembled those of the donor's serum Tg antibodies. Blood lymphocytes transferred to SCID recipients were also able to produce Tg antibodies of subclasses 1, 2 and 4 but the subclass distribution varied between mice and the reason for this is not clear at present. Since SCID mice provide an environment in which B lymphocytes from patients with AITD can be activated without mitogen to secrete thyroid antibodies, this model will provide a powerful system for elucidating the mechanisms regulating the secretion of human antibodies to Tg and TPO.

The influence of preoperative drug treatment on the histological appearances and in vitro 131I uptake of human hyperplastic thyroid gland.

The specimen of thyroid resected at partial thyroidectomy from 103 patients with primary thyrotoxicosis was studied with histometric and organ culture techniques. Twenty-seven patients had been prepared for operation with propranolol and seventy-six with carbimazole: all received Lugol's iodine for 10 days before operation. The resected specimen and deduced total thyroid weight was greater in the patients prepared with carbimazole. There was no absolute qualitative histopathological difference in the appearance of the glands of the two groups of patients, but histometry showed that the volume percentage of colloid and total gland colloid weight was significantly greater in the patients prepared with carbimazole: the volume percentage of epithelial cells and the total gland epithelial cell weight was similar in the two groups. The iodide concentrating capacity per g wet weight thyroid tissue or per unit volume of colloid did not differ significantly between the two groups. However, the iodide concentration capacity per unit volume of epithelial cells was significantly higher in the carbimazole prepared patients than in those prepared with propranolol.

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.