THE POISONOUS YEW

531 in both series. Of the post-variolar cases six As the heart settled down to the slow rate, however, occurred in the London area, while post-vaccinal cases the blood pressure returned to its normal height. also tended to appear in groups. Investigation of the slowing of the heart-rate, by taking simultaneous records of the auricular and ventricular beats, by electrocardiography, and by THE POISONOUS YEW experiments with isolated perfused hearts, led to the IN our medico-legal column will be found a report conclusion that taxine probably slows the heart by of two recent deaths from eating yew leaves. Accidents depressing the whole of the conduction tissue. It of this kind are on record at least from the fourth was not possible to prove that it had any specific century B.C. onwards, though they are nowadays action on the central nervous system. Immersion In many European of the isolated intestine of rabbits and guinea-pigs rare enough to cause surprise. ,countries yew leaves are believed to be abortifacient, in a 1 in 100,000 solution of taxine reduced the size .and attempts have been made to use them also for of the contractions, and in a solution of 1 in 10,000 more legitimate medical purposes—e.g., for epilepsy they ceased. Injections of two-fifths of the lethal .and rheumatism, and as a heart tonic. Mr. T. Bryan- dose into intact ansesthetised rabbits increased the ]3rown, of the Oxford University Pharmacological size and frequency of contractions of the uterus. In man the symptoms of poisoning usually come Laboratory, has lately examined1 the properties of the alkaloid taxine, derived from yew, upon rabbits, on in an hour or less, but their onset has sometimes mice, guinea-pigs, and frogs. It seems fairly well been delayed for several days. They may include - established, he says, that taxine is present in large convulsions, and loss of consciousness, with dilatation quantities only in the old leaves and the seeds ; the of the pupil, pallor, and coldness of the limbs; pulp of the berries, which has a pleasant sweet taste, vomiting and purging are not uncommon, and there is almost free from the alkaloid, and can be eaten is sometimes abdominal pain. Death, or recovery, without ill-effects. He found the minimum lethal usually takes place within eight or ten hours, but dose for rabbits, by intravenous injection, to be people have been known to die as long as 19 days 0-002-0-003 g. per kg. of body-weight ; for mice, after taking the poison. Signs of severe intestinal guinea-pigs, and frogs the dose ranged from 0-012 irritation are found post mortem, and this irritation to 0-017 g. per kg., being given intraperitoneally, is often the cause of death in cattle. Some degree of subcutaneously, and into the dorsal lymph sac tolerance can, however, be acquired, and Bryan-Brown respectively. The toxicity of the alkaloid is quotes a statement that in Hesse the peasants feed diminished by keeping ; after ten months in storage their cows on yew in winter, offering them only a it was found that the minimum lethal dose required very little at the outset and later increasing the to be increased by 60 per cent. The symptoms of amount. poisoning were essentially the same in all the animals THE RELIEF OF PAIN IN ANEURYSM used. A few minutes after subcutaneous injection THE part which surgery can play in the treatment of a lethal dose into a guinea-pig the animal became apt first restless, and, after a further few minutes, of diseases of the heart and blood-vessels is gradually languid and unwilling to crawl, though able to do so. becoming clearer. For example, destruction of the After another five minutes it tried to lie prone, but dorsal sympathetic rami is now proving superior to was hindered by periodic twitchings of the limbs ; operations on the cervical sympathetic chain in angina it became too weak to crawl, and respiration was pectoris, and lately this procedure has also been shown slowed from the normal rate of 114 per minute to to be useful in alleviating the pain of aortic aneurysm. 90. Violent clonic convulsions presently appeared, Usually aneurysm of the aorta does not cause much at intervals of 10 to 15 seconds, which lasted from pain ; nevertheless, this is sometimes very severetwo to five seconds and affected the hind limbs even apart from the complication of angina-being especially ; respiration was further slowed to 60 per probably due to pressure on neighbouring structures. minute. Shortly afterwards respiration became J. C. White1 reports three cases of this kind successperiodic; the animal could not right itself when fully treated with paravertebral injections of procaine placed on its side, but the corneal reflex was still and alcohol. The technique is similar to that used present. Respiration later became gasping, the in the treatment of angina pectoris by paravertebral .comeal reflex disappeared, and the convulsions injections, and the object is to destroy the sympathetic became feebler; finally, about 45 minutes after the rami communicantes as they pass from the sympathetic ganglia to the ganglia upon the posterior nerveinjection, the guinea-pig died. The effect on respiration was found to vary in roots. It requires accurate knowledge of the anatomy different individuals ; frequently the rate was at of the region, and in describing the technique measurefirst accelerated, and periodic respiration, though ments are of limited value, for they vary very widely common, was not a constant sign. The stages with the build of the patient. The most important succeeded each other more rapidly when the lethal structure to avoid in making the injections is the ,dose was given intraperitoneally, and after intra- pleura. White does not describe his method in detail, venous injection the animals collapsed suddenly but no doubt he uses a manometer in connexion with and died after two or three convulsions ; in frogs the needle, so that a warning may be given if the - convulsions failed to develop after the injection of a pleural cavity is entered. A preliminary injection lethal dose, though the symptoms were otherwise of procaine is given to determine which nerve-roots comparable to those found in mammals. A further are concerned in the pain, and this is followed by series of experiments showed that taxine had no 5 c.cm. of 95 per cent. alcohol into the appropriate effect on the blood pressure if less than one-third nerve-roots. In the three cases described, blocking of the lethal dose was given. For several minutes of two roots only-the first and second dorsalafter the injection of such a dose the only change was required. An anaesthesia of the corresponding was a slight slowing of the heart-rate ; then, quite intercostal nerve areas is produced, but this never suddenly, the rate would drop to half normal or less, lasts more than a few weeks, while the relief from pain and this drop was frequently accompanied by a fall is considerably longer. From this it would appear of about 30 mm. of mercury in the blood pressure. that the pain impulses are actually carried by the :seen

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1 Quart. Jour. Pharm.

and

Pharmacol., 1932,

v., 305.

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Jour. Amer. Med. Assoc., July 2nd, p. 10.