WAR EXPLOSIVE.

Auckland Star, Volume LXVII, Issue 139, 13 June 1936, Page 26

WAR EXPLOSIVE.

AS INFECTION CHECK. PICRIC ACID EXPERIMENTS. TRIED ON MICE AND MONKEYS

(By THOMAS R. HENRY.)

WASHINGTON. May 8. One of the most potent or war explosives promises to be a noteworthy agent in checking th? spread of such epidemic maladies as encephalitis and infantile paralysis. .Experiments on checking infections with the viruses of these dreaded diseases with picric acid have just been reported by Dr. Charles Armstrong and Or. W. T. Harrison, of the I nitcd States Public Health Service. In war this intensely bitter yellow powder when mixed with other ingredients and placed in shells was a terrible agent of death. The Public Health Service doctors simply spray a minute amount of it in the nose. They used mice and monkeys to test, its ellicacv in preventing virus infection, but they also sprayed it jn their own nostrils to determine* whether it had any harmful effect on human beings. They found none. It now is generally recognised that the nerve tracts of the nose constitute one of the routes—perhaps the principal onc —l,y which the extremely minute organisms responsible for these diseases make their way into the human nervous system. For a year or more Or. Armstrong and Dr. Harrison have been searching for some substance wliieii would serve as an effective bar to this unprotected portal, wide open for any disease germs which might be in the atmosphere.

Alum-Found Helpful. Earlier experiments indicated that alum had a notable effect, in increasing resistance, perhaps because of its wellknown "puckering" eiTect, which made it more difficult for the organisms to get a foothold. First the nostrils o£ mice would be sprayed witlw an alum solution and then drops of a solution containing one of the viruses would be oiven. It was found that fewer animals developed the disease than in cases where 110 alum was used. They then set to work to test other substances—among them cobra venom, salt water, plain distilled water, formalin, zinc and ammonium chlorides, tannic acid, lead acetate, sea water, thymol and quinine hydrochloride, home showed no effect at all. Others were effective, but extremely irritating to the nostrils. Some of them, in fact, killeu the animals used in the experiments. The best effects were obtained wit.i picric acid, either pure or mixed with alum. From SO to 100 per cent of the mice and monkeys so treated did not. develop the disease. Nearly all developed it .without such protection. The effect of the picric acid instillation in the nose, Drs. Armstrong and Harrison report, is not confined to protection against the ultra-viruses which tret into the body directly through this portal and thence, by way of the olefactorv nerve tract, to the tissues of the brain. They tried the protection afforded in cases where the poliomyelitis virus was injected directly into the blood stream.

Protection Not Complete. Of nine monkeys so treated, only two developed the fatal disease. Of nine subjected to intravenous injection without. the picric acid instillation in the nose, six died of poliomyelitis. This leads to the tentative hypothesis that the disease does not reach the pram through the blood stream unless the virus passes from the blood to the | olefactory tract. The picric acid did not afford a'complete protection. <( .~ "Tliis," reports Dr. Armstrong, is possibly to be explained by the assumption that certain portions of the nasal membranees inaccessible to intra nasally instilled picric acid are likely inaccessible to virus by the same route, but accessible to virus from the blood stream. It is conceivable, however, that infection from the blood stream into the central 'nervous svstem may occasionally take place, either at levels of the membrane too deep to be influenced by picric acul applied to the surface, or even by a more direct escape of virus from the blood vessels, especially following seveie shock." .... . • •1 The only cases in which the picric acid protection failed were those in which the virus was injected directly into the brain.

Holds for Four Days. The time interval over which a single picric acid instillation afforded protection was tested. In most cases monkey s inoculatad with the virus seven days after the instillation did not develop the disease, but the results were quite uncertain. The protection seemed to hold perfectly for a four-day interval. Savs the report: "Picric acid apparently produced no general ill-effect 111 mice or -monkeys, nor did it produce changes detectable by ordinary pathological methods in the nasal mucous membranes. That it exerts its protection through a local action is indicated by'the fact that .picric acid administered to mice apparently affords 110 protection against intracerebrally inoculated virus. This'local action may consist in some alteration in the nasal membranes which render tlicm less permeable to the virus, although it is conceivable that the drug, either free or united with the cells of these structures, may exert a direct effect on the virus While various poliomyelitis vaccines have been introduced in.the past few vears, their protective value has been debatable. No protective vaccine or serum has been developed against encephalitis. Practically every summer for the past five years there have been epidemics of one or the other of these diseases in some part of tlic e°uiltr>. Medical science has had little to offei against them. . The picric acid instillation developed by the Public Health Service doctors appears to be the most effective preventivc measure yet devised. N.A.N.A.