Effect of THD-341, a new hypocholesterolemic agent, on experimental atherosclerosis in rabbits

The influence of THD-341, N-(2,6-dimethylphenyl)-delta8-dihydroabietamide, upon the formation and regression of atherosclerosis and on serum and liver lipid levels has been studied. When rabbits were fed a 1% cholesterol diet for 7 weeks, THD-341 added at a dietary level of 0.01% during the last 4 weeks almost completely prevented the formation of atherosclerotic lesions and the elevation of serum and liver cholesterol levels. When the drug was fed for 10 weeks, either in the normal or cholesterol diet, to rabbits with pre-established atherosclerosis induced by cholesterol feeding for 11 weeks, it did not affect the extent or severity of the lesions but inhibited the progression of lipid deposition in the aorta in a group fed the cholesterol diet during the final 10-weeks period. The reduction of serum and liver cholesterol levels was greater in the drug-treated groups than in the normal rabbit chow-fed group.

Hypocholesterolemic action of a novel delta8-dihydroabietamide derivative, THD-341, in rats

The hypocholesterolemic properties of THD-341, N-(2,6-dimethylphenyl)-delta8-dihydroabietamide, were studied in rats. THD-341 reduced serum cholesterol levels in cholesterol-cholate-fed rats at a concentration of less than 0.001% in the diet or an oral dose of less than 3 mg/kg, once a day. When compared in terms of the 50% inhibitory dose for serum cholesterol elevation (ID 50%, % in diet), THD-341 (0.0008%) was comparable to D-thyroxine (0.0005%), more potent than estradiol (0.003%), and far more potent than clofibrate (0.2%), beta-sitosterol (0.8%), cholestyramine (2%), or nicotinic acid (3%). A daily intravenous injection of THD-341 was also effective (ID 50%: 7 mg/kg). THD-341 reduced serum and liver cholesterol in rats made hypercholesterolemic by 0.3% dietary thiouracil or 0.25% dietary cholate. Liver cholesteriol was more profoundly affected than the serum cholesterol. In normal rats, cholesterol was reduced in liver but not in serum. Its mechanism of action is unknown but the results suggest that THD-341 inhibits cholesterol absorption or re-absorption.

[Microdetermination of TSH in dried blood spot--its use in the mass-screening for congenital or juvenile primary hypothyroidism (author's transl)]

Blood TSH (Thyroid Stimulating Hormone) was successfully measured by radioimmunoassay in a dried blood spot on filter paper which is obtained in newborn screening for metabolic disorders. By this method, the minimal detectable level of blood TSH was about 10 muU/ml, which is the approximate upper limit of normal values of blood TSH. Good correlation was found between the TSH values obtained from this specimen and from liquid serum samples from the same subjects. The duplication of assay of a single sample was not necessary. A screening program using the method described here was initiated and a 4 year old infant was found to have primary hypothyroidism, later verified by other testing methods. Since the technique is simple and adequately sensitive for the detection of hypothyroidism, it could be a valuable method for use in mass-screening of newborns for congenital hypothyroidism.

[Studies on the TRH test on the patients with Graves' disease during the treatment with antithyroid drug (author's transl)]

A study was performed to observe serum TSH response following TRH injection (TRH test) in 79 cases of Graves' disease (male 23, female 56, aged 16-70 years old), before and during treatment by antithyroid drug, in a total of 244 occasions. Treatment was mostly the daily administration of methyl-mercaptoimidazole (MMI), and in one case of propylthiouracil (PTU). TRH test was conducted by i.v. administration of 500 mug synthetic TRH, and subsequent 6 blood drawing until 2 hours. Serum TSH was measured by radioimmunoassay in each serum, and serum T4, T3, RT3U and cholestrol were measured in the serum before TRH injection. In some cases, the results of TRH test were compared with those of T3 131I thyroidal uptake suppression test, using the 131I uptake values at 20 min. and 24 hours. Results were obtained as follows: 1) Some cases showed positive TRH test at the early stage of treatment when the patients were in eumetabolic states, while many patients showed no TSH response in spite of their long maintenance at eumetabolic states. 2) When both serum T4 and T3 were high, all cases showed no response of TSH. When serum T4 alone was high, all cases except one case showed no response;whereas when serum T3 alone was high, 5 cases showed normal response. When both serum T4 and T3 were below normal, 2 cases showed no response. When serum T4 was low, all cases showed response; whereas when serum T3 alone was low, 6 cases showed no response. Thus, there was no positive correlation between TSH reactivity and serum concentrations of thyroid hormones. 3) No correlation was observed between TSH reactivity and the period after the onset of hyperthyroidism. 4) In 57 cases of Graves' disease, who were under treatment and in eumetabolic states, a comparison was made between TSH reactivity and the results of T3 suppression test. In T3 suppressed group, 19 showed response, and 3 showed no response; whereas in T3 non-suppressed group, 18 showed response and 17 showed no response. In the group of T3 non-suppression as well as in the group of T3 non-suppression plus TRH no response, there was a significant elevation of serum T3 compared with the control group. 5) TRH test does not appear to be an appropriate test as a predictive method to know the permanent remission of Graves' disease.