[Inhibition of cholinesterase activity induced by pyridaphenthion]

Inhibitory effects on cholinesterase (ChE) activity in blood of the rabbit induced by pyridaphenthion(PD), an organophosphorus compound, and effects of 2-pyridine aldoxime methiodide(PAM) on this inhibition were examined. 1) Experimental results within 24 hr: An oral administration of each dose of PD(100 approximately 750 mg/kg) gradually decreased ChE activity and ChE activity value decreased to 20.5% in the erythrocytes and 21.5% in the plasma 24 hr after administration of 500 mg/kg of PD. However, this value recovered remarkably with an intravenous injection of PAM. The ChE activity value was 55.5% in the erythrocytes and 41.4% in the plasma with a single injection, and respectively 67.8% and 59.1% when PAM was injected three times. 2) Experimental results for 14 days: Following an increase of the administered dose (100 approximately 400 mg/kg) of PD, a decrease in ChE activity was apparent and a recovery to normal values was delayed. This inhibition could be ameliorated quickly with an injection of PAM. Considering that PAM does not have remarkable detoxicative effects on organophosphorus compounds which have a low toxicity, PAM appears to be a promising antidote against PD.

Staining mycobacteria with carbolfuchsin: properties of solutions prepared with different samples of basic fuchsin

Acid fast staining of mycobacteria in the form of beadings is obtained by means of a carbolfuchsin solution (Ziehl-Neelsen stain) prepared from pararosaniline or from certain kinds of basic fuchsin. After such acid-fast stains, the intensity of the bacilli's colouring was rather poor and unstable, so that some bacilli lost their acid-fast stain. In contrast, an acid-fast staining of mycobacteria in rod form results by using a carbolfuchsin prepared from rosaniline or from other basic fuchsins included new fuchsin. The spectrophotometric and thin-layer chromatographic data indicate that the main component of those basic fuchsins showing beady staining may be pararosaniline, whereas the main ingredient of basic fuchsin with staining the bacteria in rod form may be its higher homologues. Neither chloride nor acetate of the fuchsin could affect the appearance and number of stained bacilli. The commercially available "basic fuchsin" is either the chloride or acetate of pure pararosaniline or consists of variable mixtures of it with higher homologues. Consequently, only a basic fuchsin which has an absorption maximum at lambda greater than or equal to 552 nm could be employed for the acid-fast stain of mycobacteria in a stable manner. Pararosaniline included some basic fuchsins, composed mainly from pararosaniline, should not be selected for the preparation of the carbolfuchsin formula.

[Metabolism of arsenic (15). Influence of arsenic antidotes on intestinal absorption of arsenic trioxide]

A loop ligated at both sides was made in the ilecoecal portion of rabbit intestine. As2O3 solution was infused into this loop and the blood circulating around this loop was collected from the cannulated vein. As2O3 content absorbed in blood as well as that remaining in this loop were determined. In control rabbits on no drugs, approx. 30% of As2O3 infused was absorbed into the blood in 60 minutes. However, in rabbits on parenteral dimercaprol (BAL) or thioctic acid (TA), the content of As2O3 absorbed into the blood decreased remarkably while the content of As2O3 remaining in the loop increased. On the other hand, even when BAL or TA were added directly into thip loop containing As2O3, the content of As2O3 absorbed in blood decreased markedly, compared with that of the control group. Thus it was demonstrated that BAL or TA combined with AsO3(3-) after being excreted into the intestinal tract from the bile-duct, bringing about inhibition of the enteral absorption of As2O3.