Principal serum iodothyronines, T₄, T₃ and rT₃, have been simultaneously measured by a specific radioimmunoassay in piglets kept for sequential observation with the mother from 1 to 21 days of age. During several hours postnatally, a high concentration of the hormone was noted as a result of an enhanced secretory activity of the thyroid gland. Later, a progressive decrease with a nadir at about day 3 was observed, followed by a second rise in the hormone level. Changes in T₃ and rT₃ levels from birth to the end of the 1st week, paralleled those for T₄. The T₃:rT₃ ratio of about 2 during the 1st week fell to about 1.5 during the 3rd week as a result of the progressive increase in rT₃ and decrease in T₃ concentrations. The T₄:rT₃ ratio fell with the progressing age to the level observed in post-weaned pigs. At birth, the newborn pig seems to possess a low capability of 5-deiodinase enzyme system thus the converting enzymes first work towards T₄–T₃ conversion while T₄–rT₃-converting ability progressively increases with age. The role of this variability for the neonatal thermogenic stability is discussed.

INTROduCTION Livin belongs to the family of apoptosis inhibitors. High livin expression is observed in malignancies of the gastrointestinal tract, lungs, breast, and kidneys, but it is not present in differentiated adult tissues. In some malignant processes, anti-livin antibodies are present.ObjECTIvEs The aim of the study was to evaluate the prevalence of anti-livin antibodies in Hashimoto thyroiditis, a disease characterized by rapid and widespread thyrocyte apoptosis. PATIENTs ANd mEThOdsThe study comprised 65 women with Hashimoto thyroiditis and the control group of 40 healthy women. In the majority of the patients, clinical manifestations of hypothyroidism were observed; all patients had high levels of serum antithyroid peroxidase antibodies. A solid-phase radioimmunoassay in livin-coated polyethylene tubes using 125I-labeled protein A was used to determine anti-livin antibodies.REsuLTs Significant amounts of anti-livin antibodies were reported in 18 patients (26.8%); 3 patients (4.6%) had borderline antibody levels; while in controls only 1 patient was positive (2.5%, P <0.0001).CONCLusIONs In Hashimoto thyroiditis, an autoimmune process is more general and involves numerous autoantibodies including an antibody against apoptosis inhibitor -livin. Anti-livin antibodies cannot serve only as a marker of malignancy because they are also present in autoimmune processes. KEy wORdsanti-livin antibodies, Hashimoto thyroiditis