Arthur P. Richardson

An unusual case of neuromuscular blockade seen with therapeutic blood levels of colistin methanesulfonate (Coly-Mycin)

Abstract Colistin methanesulfonate given in single small doses produced muscle weakness and fatigability in a patient with severe Sjogrens syndrome and rheumatoid arthritis. The weakness occurred in the presence of therapeutic blood levels of the drug, and was for the most part reversed by the administration of Tensilon. No underlying abnormality of neuromuscular transmission could be found, but a mild abnormality was present on biopsy. The subject of neuromuscular blockade with antibiotics is reviewed briefly, and the possible mode of action of colistin methanesulfonate in this case is discussed.

Metabolism of Methyl and Benzyl Esters of Penicillin by Different Species

Conclusions Plasma levels following administration of benzyl and methyl esters of penicillin G have been determined in a variety of species of animals. Mice hydrolyze both of these esters rapidly and probably completely. Rats are able to hydrolyze the esters less completely. Monkeys, dogs, and rabbits show no appreciable plasma level of free penicillin following subcutaneous injection of ordinary doses of these esters.

Effect of pentaquine on cardiovascular system of unanesthetized dogs.

Conclusions The repeated administration of high doses of pentaquine produces an effect upon the cardiovascular system such that unanesthetized animals develop a striking postural hypotension. Pentaquine has no effect upon the response of animals to epinephrine, but blocks the tachycardia produced by acetylcholine. It is suggested that these effects are produced by an impairment of the central portion of the sympathetic nervous system.

Reticulocytogenic Effects of Liver Extract and Congo Red in Guinea Pigs under Reduced Oxygen Tension

Conclusions Guinea pigs subjected to reduced oxygen tensions showed prompt rises in reticulated red cells which reached a peak (8-14%), in 7-12 days. Then the reticulocytes decreased and in 3-4 weeks approached the control level. Intramuscular injection of liver extract prior to, simultaneously with, or following, exposure to reduced oxygen pressure, had no demonstrable effects on the reticulocyte response; and the bone marrow of liver-treated animals could not be distinguished from that of untreated controls. Congo red was also without effect on the reticullocyte response of guinea pigs under reduced oxygen tensions.

Comparative effects of Congo red and liver extract on reticulocytes in pigeons.

Conclusion 1. The variation of reticulocytes in normal pigeons has been determined. 2. Concentrated liver extract, injected intramuscularly, produced the usual rise in reticulocytes in normal pigeons, while Congo red, injected intravenously in the same and other pigeons for days, did not. This does not mean that Congored can not act beneficially in pernicious anemia. The difficulties of bioassaying antipernicious anemia agents in normal animals are real and not always appreciated.