Iodide-deficient female rats were fed propylthiouracil (PTU) or dl-5-vinyl-oxazolidinethione mixed into a low-iodide diet for 10 days and then were either maintained on a low-iodide diet or given iodide supplements. Recovery of thyroid function after withdrawal of the antithyroid agents was markedly affected by the iodide supplementation. Without the iodide supplement 1) there was no regression of goiter or increase in serum PBI concentration; 2) the uptake of 131I by the thyroid was rapid and the 4-hr uptakes showed the expected ‘rebound’ phenomenon; 3) the 131I which was accumulatedby the 4th hr after administration was rapidly lost from the gland so that the 24-hr values were low and did not show the “rebound” phenomenon; 4) the ratios of radioactive DIT%MIT and T4%T3 were reversed; 5) there was a rapid loss of 131I-labeled MIT and DIT from the thyroid between the 4th and 24th hr after isotope administration, commencing 1 day after withdrawal of the drug, and a rapid loss of radioactive T4 and T3, commencing 3–4 days later. All these effects were corrected by iodide supplementation. (Endocrinology83: 452, 1968)

Crude pituitary extracts and partially purified FSH and LH fractions from a variety of species have been shown to possess little, if any, cross-reactivity in hormone-specific radioimmunoassays for human FSH and LH. PMSG did not cross react in the FSH immunoassay.

1. The following 9 alkaloids isolated from seeds of species of the genus Erythrina: erythramine, erythraline and erythratine (free alkaloids), erysopine, erysovine, erysodine and erysonine (liberated alkaloids), and erysothiopine and erysothiovine (combined alkaloids) produce typical curare-like action. 2. The potency of these alkaloids and of some derivatives has been determined on frogs; the greatest activity was found with the combined alkaloids. 3. The combined and the liberated alkaloids have a more persistent action than the free alkaloids. 4. The order of toxicity of various alkaloids in mice following oral and subcutaneous administration followed, in general, that of their potency in frogs. 5. Intravenous injections especially of the liberated and combined alkaloids depressed the blood pressure and lowered the heart rate to a greater extent than did β-erythroidine. 6. Atropine failed to influence the bradycardia in cats and dogs anesthetized with sodium pentobarbital. 7. In contrast to the findings with β-erythroidine and dihydro-β-erythroidine, hydrogenated derivatives of erythramine, erythratine, erysopine and erysodine are less active than the parent alkaloids. 8. The quaternary metho-salts of erythramine, erythraline and erythratine are, like that of β-erythroidine, less active than the tertiary bases.

1. β-Erythroidine and substances derived from it (dihydro-β-erythroidine, α-tetrahydro-β-erythroidine, β-tetrahydro-β-erythroidine, sodium β-erythroidine, sodium dihydro-β-erythroidine, and β-erythroidine methiodide) possess typical curare-like action. 2. Compared with curare, the paralysis caused by these alkaloids, especially β-erythroidine, is of short duration. 3. Dihydro-β-erythroidine is the most potent of these alkaloids; it equals curarine in potency. 4. β-Erythroidine and dihydro-β-erythroidine are effective by oral administration. The toxicity has been determined in mice, rats, rabbits and cats following subcutaneous and oral administration. 5. Death in mammals is caused by paralysis of the diaphragm; the heart continues to beat in regular rhythm for several minutes. 6. Intravenous injections of β-erythroidine or dihydro-β-erythroidine cause a transient fall in blood pressure. In dogs they decreas emarkedly the heart rate and increase the atrio-ventricular conduction time. 7. Atropine prevents the bradycardia in non-anesthetized dogs, but fails to influence the bradycardia in animals anesthetized with sodium pentobarbital. 8. The smooth muscle is not affected by β-erythroidine. 9. Prostigmine is an effective antidote against β-erythroidine and dihydro-β-erythroidine. The antagonism between prostigmine and the two Erythrina alkaloids is mutual. 10. In contrast to the well known relation of tertiary and quaternary ammonium groups in curare alkaloids to their neuro-muscular action, conversion of β-erythroidine into the quaternary metho salt (β-erythroidine methiodide) decreases the curarizing action to about one-hundredth of the tertiary base.

1. The L.D. 50 of riboflavin in rats following intraperitoneal administration is 560 mgm. per kgm. Death occurs within 2 to 5 days with signs of anuria and azotemia and is due to obstruction of the kidney by concretions. 2. Oral administration of riboflavin to rats (10 grams per kgm.) and to dogs (2 grams per kgm.) failed to produce any toxic effects. The low solubility of riboflavin prevents its absorbtion from the gastro intestinal tract in amounts sufficient to produce toxic effects. 3. Daily administration of riboflavin over periods of 4 months to rats (10 mgm.) and dogs (25 mgm. per kgm.) failed to produce any toxic manifestations. Rats receiving 10 mgm. daily were raised through 3 generations. 4. The metabolism, the circulatory and respiratory systems, and isolated smooth muscle organs of animals maintained on adequate diets are not influenced by riboflavin.