Adsorption equilibria of thyroid hormones in the liver cell

Inhibitory and disruptive effects of some antirheumatics on antigen-antibody complexes

Purified antibodies to human serum albumin or to human gamma-globulin were used to study the direct influence of some antirheumatic drugs on the formation and disruption of immunoprecipitates. 125I-labelled human serum albumin and 125I-labelled human IgG served as indicators. The effects of the following drugs were described: diclofenac, monophenylbutazone, diphenylbutazone, ibuprofen, and metamizol. At approximately therapeutic concentrations, the antirheumatics inhibited the formation of complexes of homologous antibodies with human serum albumin and, surprisingly, with human IgG. When the antigens were precipitated with antibodies, subsequent addition of the antirheumatics to the preformed immunoprecipitates caused disruption of [125I]human serum albumin-anti-human serum albumin precipitates but practically no disruption of human [125I]IgG-anti-human IgG precipitates. These new findings may be of relevance for clinical diagnosis and therapy as well as for research in immunochemistry. It is conceivable that, in patients, antirheumatic or other drugs might interfere with immunological determinations of clinico-chemical quantities. Interference of drugs with antigen-antibody reactions might also help to explain some beneficial effects or undesirable side effects of certain drugs.

Molecular interconversion of cold-sensitive cytosolic 3,3',5-tri-iodo-L-thyronine-binding proteins from human erythrocytes: effect of cold, heat and pH treatments

Cytosolic 3,3',5-tri-iodo-L-thyronine-binding proteins (CTBP I, II and IV species) from human red blood cells undergo rapid loss of activity at low temperatures. Cold treatment of CTBPs was accompanied by dissociation of the polymeric protein to the 60 kDa inactive monomer. Re-activation of the cold-inactivated CTBP IV by warming resulted in association of the monomer to the active polymeric form. A similar association-dissociation phenomenon was also obtained isothermically, though pH changes. We conclude that CTBP I and CTBP II are polymeric forms of CTBP IV.

Influence of thyroid hormones and testosterone on the activities of hepatic mitochondrial enzymes in the Indian garden lizard, Calotes versicolor

Thyroidectomy and castration in Calotes versicolor significantly decreased the activities of hepatic mitochondrial cytochrome oxidase, alpha-glycerophosphate dehydrogenase (alpha-GPDH), and succinate dehydrogenase (SDH) when compared to sham-operated controls. Administration of thyroid hormones in thyroidectomized lizards and testosterone in castrated specimens stimulated the activities of all three enzymes studied. Chloramphenicol, when injected with thyroxine prevented the hormone-stimulated activities of cytochrome oxidase and SDH, while actinomycin D and chloramphenicol, when administered along with testosterone propionate (low dose) prevented the testosterone-stimulated activities of cytochrome oxidase and alpha-GPDH.

Heat exposure and hypothyroid conditions decrease hydrogen peroxide generation in liver mitochondria

Exposure of rats to heat (39 +/- 1 degree C) decreased H2O2 generation in mitochondria of the liver, but not of the kidney or the heart. The effect was obtained with three substrates, succinate, glycerol 1-phosphate and choline, with a decrease to 50% in the first 2-3 days of exposure, and a further decrease on longer exposure. The dehydrogenase activity with only glycerol 1-phosphate decreased, which is indicative of the hypothyroid condition, whereas choline dehydrogenase activity remained unchanged and that of succinate dehydrogenase decreased on long exposure. The serum concentration of thyroxine decreased in heat-exposed rats. Thyroxine treatment of rats increased H2O2 generation. Hypothyroid conditions obtained by treatment with propylthiouracil or thyroidectomy caused a decrease in H2O2 generation and changes in dehydrogenase activities similar to those with heat exposure. Treatment of heat-exposed or thyroidectomized rats with thyroxine stimulated H2O2 generation by a mechanism apparently involving fresh protein synthesis. The results indicate that H2O2 generation in mitochondria of heat-exposed animals is determined by thyroid status.

[Familial coincidence of hypertrophic cardiomyopathies and thyroxine-binding globulin deficiency (athyropexinemia) (author's transl)]

A twenty-five year old man was found to have simultaneous total deficiency of thyroxine-binding globulin ("thyropexin") and hereditary hypertrophic obstructive cardiomyopathy (HOCM). The thyroxine-binding capacity (RT3U), thyroid hormone levels, PB127I, PB131I and TBG (RIA) in serum were very low and TBG cap was zero. Trapping of radioiodine in the thyroid was enhanced. Clinically, the patient appeared euthyroid. The case seems to be similar to another one described earlier by Ingbar. An investigation of the family showed that in one uncle and two nephews of the patient thyropexin was absent whilst the mother, one sister and one female cousin had partial thyropexin deficiencies. One of these nephews also suffers from asymmetric septal hypertrophy (ASH), the mother of the propositus has a non-obstructive hypertrophic cardiomyopathy (HCM).