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tests on the two standard sera tested at 10% differencesgave the following results : (a) 95, 95, 95, 88 units perml. ; (b) 2-07, 1-90, 2-10, 1-93 units per ml.Thus we found in this series of three tests that the

mother’s serum failed each time to pass tests for 22units but was over 18 or 20 units, whereas the serumfrom the cord blood was over 36 units on each of the fouroccasions it was tested. The values allotted were 21 and41 units respectively, and the high titres were due to thefact that the mother had been immunised earlier in

pregnancy. °

In conclusion I would suggest a better idea than Dr.Wiener’s as to the relation between theory and observa-tion : when an observation of undoubted accuracyconflicts with " an excellent theory," it is also a goodthing to re-examine the theory. As yet we have no theoryto account for the phenomenon, but we are continuingthe investigation—giving due consideration to anypoints on the practical side which might throw light onthe matter.Wellcome Research Laboratories,

Beckenham, Kent.MOLLIE BARR.

VASCULAR STASIS

SIR,-I read with great interest last week’s letter onvascular stasis by Professor Kreyberg, of Oslo, and yourannotation ; and I should like to support the plea forfurther study of this phenomenon.At this unit an investigation of experimental and

clinical burns is in progress, and we have found evidencethat the inflammatory reaction plays an important partin influencing the course of burns. ’

During a recent study 1 of experimental burns ofknown temperature applied for known periods in guinea-pigs, the permeability and qualitative blood-flow changesin the skin were investigated by the use of circulatingEvans blue and/or brilliant vital-red injected before andafter burning. It was shown : (1) that continuation ofthe dermal blood-flow in burned skin was accompaniedby -normal skin sensation, by the absence of markedoedema, and by the absence of subsequent whole-skinloss ; (2) that the development of stasis of the localblood-flow in the dermis was preceded by marked oedema,was associated with analgesia, and was followed bywhole-skin loss.

’

Further,- evidence has been provided of the existenceof a threshold dermal temperature, below which stasisdoes not occur. If, however, the dermis is heated to orbeyond this temperature during burning, stasis of thedermal vessels develops. The time of onset of stasisdecreases with increasing severity of burning. Stasis is

preceded by a period during which slowing of the blood-flow progresses to extreme retardation or stagnation(prestasis of Kreyberg). During this period the vesselsare freely permeable and oedema develops.In our experience, stasis throughout the depth of thedermis in guineapig burns is invariably followed bywhole-skin loss, and this would suggest that the changeis normally irreversible. However, in a number of burnsin which stagnation of the blood-flow was detected,partial, and not whole-skin, loss took place. This

suggests that stagnation was not followed by stasis, orthat if stasis did develop it was localised to the superficialpart of the dermis.

Investigations are in progress with the aim of -dis-

covering how to influence these vascular changes. Variousanti-histamine drugs have failed to influence the

capillary-permeability and blood-flow changes in experi-mental guineapig burns of all degrees.2

In my opinion-and no doubt Dr. Kreyberg will

agree-stagnation and stasis, when they occur, are partof an inflammatory reaction, and any investigation into

1. Sevitt, S. J. Path. Bact. (in the press).2. Sevitt, S. Brit. J. exp. Path. (in the press).

their nature and cause must take the whole processinto account.

Finally, I should like to comment on Professor

Kreyberg’s choice of the word " prestasis " for extreme

retardation of the blood-flow. This word implies thatthe condition invariably ends in stasis, althoughProfessor Kreyberg agrees that this is not necessarilytrue. In my opinion the word " stagnation " is freefrom this criticism and is therefore to be preferred.

M.R.C. Burns Research Unit,Birmingham Accident Hospital. S. SEVITT.

AN EPIDEMIC OF ACUTE NEPHRITIS

SIR,-I read with great interest Dr. Fleming’s articlein your issue of May 7.As physician in charge of the outpatient clinic of the

Transjordanian Red Crescent Society in Amman, I facedthe same problem of an epidemic of acute nephritis amonginfants- of the Palestine Arab refugees.

In my private clinic in Amman, I have during the lastthirty months seen only three cases of acute nephritis.But in the seven months between October, 1948, andApril, 1949, I saw more than one hundred cases of acutenephritis among the refugee children. This prevalencewas due perhaps to the bad conditions under which therefugees were living (most of them were in tents or caves}and to the extremely cold and damp weather.

I did not have the advantage of a well-equippedlaboratory, nor enough beds in the hospital, to investigatethese cases fully, but the following features were noted :(1) most of the cases were in females ; (2) their age wasusually under 3 years ; and (3) commonly they had hada course of sulphadiazine in the preceding two weeks forinflammation of nasopharynx, otitis media, pneumonia,or diarrhoea. The diagnosis of acute nephritis was

based on the presence of oedema and albuminuria with orwithout fever.

In the early cases of this series treatment consisted atthe start in routine dietetic and diuretic measures, whichhad very little effect. When, after fifteen days, the condi-tion was not greatly improved, I injected 200,000 unitsof penicillin once daily for three successive days. The

improvement was so striking that I treated subsequentcases with penicillin as soon as the diagnosis was made ; ;.in the majority cure was complete within one week.

This experience contrasts with that of Dr. Fleming.But I believe that had he used greater amounts of peni-cillin, or subdivided the dose into smaller amounts givenat shorter intervals, his results would have been different.

Amman, Transjordan. M. RAZZAZ.

PURIFIED TOXINS FROM COBRA AND BEE

SIR,—I have developed a technique for preparing inpotent amorphous and crystalline form the venom fromthe cobra (Naja tripudians).The cobra is allowed to bite a rubber membrane covering

a small beaker. The venom thus collected, which consists,of about 1 ml. of viscid, clear, transparent liquid, is diluted100 times with physiological saline solution. It is clarifiedby adding a little aluminium sulphate and lime water;.and toxin is then precipitated by the addition of pure acetone.The precipitate is centrifuged, washed with acetone and thenwith ether, and finally dried in vacuo, leaving the toxin as awhite -amorphous substance. Alternatively the precipitatemay be concentrated by evaporation under reduced pressureat 30°C and the toxin crystallised by drying in vacuo overphosphorus pentoxide. One bite produces 104 mg. of thefinal crystalline toxin.

This crystalline material is strongly active when

injected subcutaneously into rats ; 0-03 mg. is sufficientto kill an albino rat of 100 g. body-weight.A second method of preparation is as follows :The venom, which is collected as in the first method, is

diluted 100- times with N/10 hydrochloric acid and is thenneutralised with normal caustic soda ; a saturated aqueous

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solution of picric acid is added and the liquid allowed to standfor 24 hours. The supernatant fluid is poured off and theremaining precipitate containing the toxin is repeatedlyextracted with 80% acetone in water until no further picrateis recovered. The toxin is then precipitated as hydrochlorideby adding a few drops of concentrated hydrochloric acid andan excess of acetone to the 80% acetone extracts. Thetoxic precipitate is centrifuged off, washed successively withacetone and ether, and kept in vacuo over phosphorus pent-oxide. The potency of this toxin, in terms of the minimallethal dose for the rat, was about 0-03 mg. per 100 g.body-weight.The resulting purified " toxin " dissolves readily in

distilled water to give a clear solution. With an aqueoussolution containing 1 mg. per ml., the Millon, xantho-proteic, and biuret reactions were positive. There wasno precipitation on boiling or half-saturation withammonium sulphate. (Half-saturation with ammoniumsulphate produced a small flocculent precipitate whichwas non-toxic in a solution containing 4 mg. per ml.).The toxin was completely precipitated by full saturationwith ammonium sulphate, by absolute alcohol, and byacetone. Picric acid gave a precipitate which dissolvedon heating and reappeared on cooling. The substance’s

general behaviour was that of a proteose. Burning ofthe dried toxin left no residue.Bee Toxin.-I have also prepared toxin from the hive-

bee (Apis mellifica) in amorphous form, as follows :Fresh telsons are mixed with a small quantity of quartz

sand, moistened with 1-2 ml. of N/10 hydrochloric acid,and ground thoroughly in a mortar for about half an hour.The finely ground mass is extracted with N/10 hydrochloricacid, using 30 ml. at a time. Five extractions are sufficientto remove all the toxin. The insoluble residue is decanted ;and the combined decanted extracts are neutralised bystirring with normal caustic soda. The toxin is precipitatedas picrate by adding saturated picric-acid solution and allow-ing the mixture to stand for 24 hours. The clear liquid isdecanted and the residue extracted with 80% acetone ;several extractions are necessary to remove all the solublepicrate. The toxin is further converted into a hydrochlorideby precipitation of the combined extracts through the additionof an excess of pure acetone and a few drops of concentratedhydrochloric acid. The precipitate is centrifuged and

filtered, washed first with more acetone and then with ether,and finally dried in vacuo.

ARMED HASSAN MOHAMMED.

Physiology Department, Abbassia MedicalFaculty, Fuad I University, Cairo.

B12 DIURESISSIR,—A rather profuse diuresis frequently attends the

administration of liver extract to patients with addisoniananaemia in relapse. Diuresis has likewise been noticedwhere the therapeutic agent is crystalline vitamin Bl2’The explanation usually offered for the diuresis ofremitting addisonian anæmia—that the hæmatocritrises at the expense of the circulating plasma-volumeand that the latter must recede by water elimination-does not accord with the fact that the hsematocrit

frequently falls (by a reversion of macrocytosis) duringthe initial period of therapy when diuresis takes place.Furthermore, remission of non-addisonian anaemia is

usually attended by water retention.Cobalt, a constituent of vitamin B12, is said to have a

diuretic effect,1 as does a liver diet instituted for thetreatment of nephrosis.2 One 3 of us had reported profusediuresis in a uraemic patient given an experimental liverpreparation of high reticulocytogenic activity.

Our decision to determine possible diuretic effects ofvitamin B12 in non-anæmic subjects arose from an

observation on an amyotrophic patient who on adrenal-cortex therapy developed water retention. The injectionof 15 µg. of vitamin B12 in solution was followed bysubsidence of cedema within a few hours in face of the1. Le Goff, J. M. J. Pharmacol. 1930, 38, 1.2. Grossmann, M. Wien. klin. Wschr. 1928, 41, 450,3. Barnard, R. D. Eye, Ear, Nose, and Throat Monthly, 1940, 19, 176.

continued administration of adrenal-cortex extract.

Subsequent observations on this patient indicated that apossible diuretic effect of vitamin B 12 should be explored.

Of 16 patients with essentially normal blood pictures,who were given 45-75 tig. of the vitamin in a singleinjection, 12 responded during the ensuing twenty-fourhours with what was felt to be an unequivocal increasein urinary output, comparison being made to controlperiods immediately before and remotely after adminis-tration. Of these 12 patients, 1 had amyotrophic lateralsclerosis, 3 chronic glomerulonephritis, 4 addisoniananaemia in remission, and 1 cardiac decompensation ;3 were normal volunteers. Another 2 volunteers and 2further patients with cardiac decompensation did notshow a definite response.While we have no evidence of the nature of the diuresis

induced by vitamin B12, a clue to the mechanism maybe found in the fact that diuresis has been found toaccompany the peripheral vasodilation (" cobalt flush ")seen in occasional patients receiving more than theordinary parenteral dose of B12. Le Goff attributedcobalt flush to the sympathomimesis of cobalt salts, andif his explanation is correct one might expect a similardilation of the glomerulo-afferent arterioles. Purely fromspeculative considerations, we are tempted to acceptLe Goff’s explanation because of the entrancing possibilitythat cobalt or a cobaltoporphyrin is either the prostheticnucleus of, or a cofactor of, the enzyme cholinesterase.Potentiation or enforcement of the enzyme might be amode of sympathomimesis..

Whatever the explanation of, cobalt or B12 diuresis,the latter does not seem to be contingent upon changesin hæmatomorphology. Possible clinical utility of B12-induced diuresis might be worthy of investigation.

New York.

ROBERT D. BARNARDHERBERT A. WEITZNER.

RADIOTHERAPY IN LEUKÆMIA

SIR,—Your annotation of Oct. 1 suggests, at leastby implication, that the most valuable method of treat-ment of chronic leukaemia is irradiation, althoughadmittedly, as an afterthought, there is a suggestionthat nitrogen mustard may be as efficacious.

In my opinion it is of the utmost importance to realisethat arsenic administered by mouth is one of the mostvaluable-perhaps the most valuable-method of treat-ment of early cases. It is of course well known that everymethod of treating leukaemia loses its efficacy sooner orlater. It is therefore important to employ the mildestmethod which will produce a good result, even if itseffect is slowly manifested. Admittedly the radio-

therapist can produce remarkable changes in the physicalsigns and in the blood picture in cases of chronic leukaemia,while often greatly improving the patient’s health ;but when his method of treatment fails, there are noother " shots in the locker." If, however, treatment isstarted with arsenic, health may often be preserved formonths or even years before radiotherapy becomesessential.

It is peculiar that the fashion for using arsenic variesso much from time to time. Naegeli advocated itsuse as the main standby in the treatment of chronicleukaemia, but then the rise of radiotherapy caused itto be relegated to a very secondary position. In 1931,Forkner and Scott 1 again made arsenic a populartherapeutic agent, but today the impressive complexityof radiotherapeutic technique and the quick (althoughusually transient) results undoubtedly have caused

many people to take the retrograde step of commencingtreatment with irradiation.

I would be prepared to state categorically that forchronic myeloid leukaemia, where the patient’s general1. Forkner, C. E., Scott, T. F. M. J. Amer. med. Ass. 1931,

97, 3.