SHAKE VENOM

Evening Star, Issue 21934, 22 January 1935, Page 7

SHAKE VENOM

A NEW REMEDY AGAINST HAEMORRHAGE A well-guarded secret has been revealed by the publication in the ‘ Lancet ’ ot a preliminary report by Dr E. G. Macfarlane, of St. Bartholomew’s Hospital, and Dr Burgess Barnett, curator of reptiles at the London Zoo, of the results so far achieved by their investigations of the coagulant properties of snake venom on blood (writes Morys Gascoyen, in the ‘ Manchester Guardian ’). The question they set out to answer was whether the coagulant action of certain snake venoms could be turned to account for the good of those unfortunate persons who suffer from the constitutional weakness known as haemophilia. This is a defect of the blood to which only males are subject, and is transmitted only through the females. Thus the son of a haomophilic father and a normal mother will not be hsemophilic; but if the same parents have a daughter the probability is that her niale children will be afflicted by the disease.

As is fairly well known persons so affected are liable to bleed to death as the result of comparatively slight wounds, because their blood lacks the quality which should cause it, when exposed to the air, to form a tough, elastic clot which contains and thereby stanches the flow. It was already known that certain snake venoms caused rapid and fatal clotting of the blood. The purpose of the investigation was ito discuss whether and, if so, how, with safety, such venoms could be used to produce in hsemophilic patients the conditions essential to prevent them from bleeding to death. COLLECTING THE POISON. The first step was to discover which of the many snake venoms had the necessary coagulant properties, for snake venoms do not all work in the same way. For the purpose of this inquiry venom has been taken from time to time over a Tong period from nearly all the great and various collection of poisonous snakes in the Zoo. The curator of reptiles and his staff are expert in the technique of the process, for the venoms have long since been collected for the purpose of preparing the antivenines which are always kept in the reptile house as antidotes against the effects of snake bites, the risk of which must always be reckoned with when so many of these poisonous animals have to be tended and handled.

The operation is most interesting to watch for those to whom it is a novelty. A simple noose of leather attached to a stiff rod is slipped over the head of the snake and pulled tight just behind it. The attendant then raises the rod with one ha d and secures the writhing body of the snake with the other. Next the curator or his deputy thrusts towards the head of the snake a glass container, padded round the edge with indiarubber' and, covered with tightly drawn oiled-silk tissue. He hold the container in a pair of strong forceps or tongs to avoid all risk of putting his hand , within reach of the snake’s fangs, and he wears goggles to protect his eyes, because many snakes are able to project their venom and direct it at the most vulnerable feature of the face. The purpose of the indiarubber pad on the container is to protect the teeth of the snake from damage. The snake bites viciously at the container, piercing the oiled-silk covering with its fangs; the pressure of the bite drives the venom from the poison glands; so that it flows through the hollow fangs into the container. When the first flow is over, the attendant passes his hand up towards the snake’s head, and, by massage, induces it to part with any residue of venom still secreted. PAINSTAKING EXPERIMENTS. With the venoms thus secured and preserved the investigators carried out a long series of meticulous and painstaking experiments, a detailed account of which they will no doubt give in reports about to be published. It was first necessary to classify the venoms as those which had coagulant action, those which had little or none, and those—a considerable number—which had the reverse effect and were anticoagulant. It was found that the only large genus of snakes in which coagulant properties were invariably present was that of the vipers, and that by far the most potent of these venoms was that of the Indian viper known as Russel’s viper. It was found that a solution of one in a thousand of this venom would clot the blood of a haemophilia patient in 17sec, when the blood from the same, patient took 35min to clot spontaneously. ■

Many other problems had to bo solved before the venom could- be apElied in practice. Each snake venom as many different toxic properties; no means has yet been found of isolating them, but it was found that the coagulant property of the venom of Russel’s viper was effective in a dilution which rendered the other toxins harmless. It was necessary to sterilise the venom without destroying its essential coagulant property, and this difficulty was eventually overcome by. filtration. And so at last it was possible to put the venom to the test on human patients.

AFTER DENTAL EXTRACTION. In their report the investigators are careful to make it clear that they are not prepared yet to put forward any definite therapeutic claims. They point merely to some encouraging clinical results. The.\ r enom has been used successfully and without any ill-effect some, twenty times on patients with

normal blood, to arrest haemorrhage. The cases included teeth extractions, removals of tonsils, and two abdominal operations. It was also successfully used to arrest haemorrhage after denta'l extraction in the cases of three patient! normally predisposed to violent haemorrhage for reasons not definitely diagnosed. Finally it was used with complete success on' four definitely haemophilia patients—twice for extraction! of teeth which it would have been most dangerous to perform without the protection of this powerful haemostatic, once to control nose bleeding when all ordinary remedies had failed, and once to arrest bleeding from wounds. Tha method of use was external application to the haemorrhage. Although the investigators . most properly resist the temptation to make any exaggerated claims as to the value of their discovery, it is proper to remark that so far there is no failure to record.