contrary, our experience leads us to believe that during the first few weeks after administration of a bone-seeking isotope most of the activity which finds its way into the skeleton does so by purely physical processes. Department of Medicine, Gardiner Institute, Western Infirmary, Glasgow.
H. I. GLASS J. MACGREGOR B. E. C. NORDIN.
RECRUITMENT FOR DERMATOLOGY SIR,-It is surprising and rather serious that advertisements for registrars in dermatology should provoke only a poor response. It is serious because there will not be the trained men to fill the many consultant posts that will arise in the near future. It is surprising because of the abundant and important opportunities and facilities offered in dermatology to the able clinician and to those interested in research and experimental medicine. If both these interests are combined in the one candidate, so much the better. You have emphasised in a recent annotationthat dermatology, unlike some specialties, has, in its advances since the war, become more broad based. It enters into every facet of medical practice. I doubt if the young man entering the field of training for a higher post in medicine realises the scope offered by a period spent in dermatological work or the facilities available for clinical and scientific study. It is to be hoped that the excitement and enthusiasm shown for this field in other countries, and particularly in America, will soon invade this country. Department of Dermatology, Royal Victoria Infirmary, Newcastle upon Tyne.
JOHN T. INGRAM.
A LOCAL ANTIBACTERIAL AGENT
SIR,-Professor Howie (June 2) is to be congratulated on a very clear exposition on the prevention and treatment of infection. He has drawn attention to many very simple ways in which cross-infection can arise and be prevented, which would escape the notice of most physicians and surgeons because so apparently obvious. Among the agents confined to local use he singles out colistin and polymyxin as being of special importance because of their activity against Pseudomonas pyocyanea. I should like to draw attention to polynoxylin (’ Anaflex ’), a local antibacterial agent, which I have used considerably for the past two years.2 simple compound, which is said by the manufacturers condensation product of formaldehyde and urea, has a very wide antibacterial spectrum.3 It is particularly effective against Staphylococcus aureus, and I have yet to encounter a strain of this organism which is resistant to it. This is in striking contrast to the older penicillins, to which, in my experience, over 50% of strains of Staph. aureus are resistant. The incidence of strains resistant to chloramphenicol and the tetracyclines is also rising steadily. 2 Polynoxylin is also effective both in vitro and in vivo against proteus and Ps. pyocyanea. In five instances of leg ulcers infected with Ps. pyocyanea all were quickly cleared by polynoxylin. This drug has also proved to be clinically efficacious against local infections with Clostridium welchii and Candida albicans. Although it is strongly inhibitory of streptococci in vitro I have not found it so effective in vivo against this organism. This, I think, is because the powdered preparation I used was unsuitable for eruptions with profuse serous discharge and crust formation. As
or pus. Apart from the removal of these before treatthe choice of preparation in which the agent is presented ment, is often veiy important. Since evidence of- polynoxylin-resistant strains of Staph. aureus is not yet forthcoming, it appears that this antibacterial agent has a definite place not only in dermatology but also This is especially as a prophylactic measure in surgery. important in view of the fact that because of its insolubility, the drug is not yet given internally. It should be a valuable preparation in surgical situations where infections with proteus, Ps. pyocyanea, and Cand. albicans are likely to appear (e.g., aural and rectal surgery and in bedsores). There is also evidence8 that as a nasal spray it is of value in the control of staphylococcal carriers.
Skin Department, Glasgow Royal Infirmary.
J. O’D. ALEXANDER.
VISITING CHILDREN SIR,-It was pleasing to see5 that unrestricted visiting to children in hospitals is now widely accepted. It is probably not generally appreciated that many local authorities still restrict visits to children in their care to one a month. This seems to be a harmful practice, even if the parents have been guilty of cruelty to the children; and surely it should not be tolerated when a child has been
admitted for purely social reasons. Perhaps an exchange of ideas between the Ministry of Health and the Home Office would produce beneficial results. " NODDY." DEHYDROGENASE ISOENZYMES SIR,-The letter from Dr. Hawkins and Mr. Whyley (May 26) prompts me to report a technique for the demonstration of lactic dehydrogenase isoenzymes (L.D.H.) using cellulose acetate. This method has the advantage of great simplicity, and it can be adopted for diagnostic use in a routine laboratory.
Samples are run in barbitone buffer, pH 8-6, 0-07 M; current 1 mA per 2-5 cm. strip. The sample is applied to the centre of the strip and run for approximately 1 hour 20 minutes. The following reagent mixture is prepared: 1 vol. M lactate, 1 vol. N.A.D. (D.P.N.) 10 mg. per ml., 3 vol. nitro blue-tetrazolium or M.T.T. (1 mg. per ml.), and 0-3 vol. methyl phenazonium metho-sulphate (1 mg. per ml.).6-S A small moist chamber is prepared, and a clean glass slide put at the bottom. When the run is completed, the reagent mixture is applied as a streak to the clean glass plate, a fresh 2-5 cm. wide strip of cellulose acetate is allowed to soak up this mixture. The electrophoresis
Professor Howie observes, the effectiveness of an antibiotic or chemotherapeutic agent is often impaired by the presence of 1. Lancet, 1962, i, 311. 2. Alexander, J. O’D. Brit. J. Derm, (in the press). 3. Haler, D., Aebi, A. Nature, Lond. 1961, 190, 734. 4. Lamont, I. C. Brit. J. Derm. 1959, 71, 201.
Isoenzymes of lactic dehydrogenase showing five fractions and albumin band (blister fluid).
strip is then removed from the tank and immediately superimposed on the blank strip into which the mixture has soaked. The moist chamber is closed and incubated. When enzyme concentration is high, the bands develop within minutes. Sera can be left to incubate for 1 hour if necessary. The strips are then fixed in 10% formalin or alcohol/acetic acid. By this method up to five clearly defined and well-separated bands can be demonstrated in tissue homogenates and in sera (see figure). The relative intensity of the bands varies with the origin of the tissue homogenates, and agrees with findings on agar and starch. Visual inspection of the strip is sufficient to reveal different 5. Lancet, July 14, 1962, p. 105. 6. Van der Helm, H. J. Lancet, 1961, ii, 108. 7. Latner, A. L., Skillen, A. W. ibid. p. 1286. 8. Wieme, R. J. Personal communication.
isoenzyme patterns in disease-e.g., an increase of L.D.H. 1 (fastest anodic fraction) in coronary thrombosis, and an increase of L.D.H. 5 (cathodic fraction) in liver disease. In sera an additional band of faster mobility than L.D.H. 1 is found. This band is not N.A.D.-dependent in its development; it is due to direct reduction of tetrazolium salt by SH groups in the albumin. This technique and results of investigations into the " nothing dehydrogenase " reaction will be presented more fully in a paper to the Biochemical Society in July. Queen Mary’s Hospital, Roehampton, HANNA BARNETT. London, S.W.15.
FLUORIDATION OF WATER-SUPPLIES SIR,-Fluoridation may be good for children’s teeth, but no one has investigated how much harm may be done to fish-and to the plankton, &c., on which fish feed-by the discharge into rivers of fluoridated effluents. It would be sad if the fish in our streams, and the pleasure they give to anglers and the food they and aquatic insects provide for birds, were destroyed. FRANKLIN BICKNELL. London, W.l. CLINICAL TRIAL OF NEW ORAL DIURETIC— SKF 8542 SIR,-In reference to the results obtained by Dr. Donnelly and his colleagues (Feb. 3), we administered
2,4,7-triamino-6-phenylteridine (SKF 8542)
(a) 4 patients who had a moderate degree of heart-failure with oedema. In 3 the results were comparable with those of other diuretics in similar conditions. In 1 patient with impaired function of the kidneys a rapid increase in urxmia was observed, which returned to normal after interruption of the treatment.
patients who had severe heart-failure with oedema and resistant to treatment with most diuretics (e.g., chlorthalidone). SKF 8542 by itself induced a slight increase in natriuresis but the combination of SKF 8542 with chlorthalidone gave very satisfactory results, with a more favourable Na/K ratio and a more pronounced weight loss than that obtained with a combination of spironolactone (’ Aldactone ’) and chlorthalidone). A representative case in the accompanying table shows a comparison of the results obtained in a patient with severe cardiac decompensation. In 1 of those patients a transient psychotic reaction was observed 2 days after interruption of the drug. (b)
(c) 4 patients with cirrhosis of the liver and ascites; here also the results were favourable. SKF 8542 appears to us to be of value in selected cases for the following reasons: (1) It evidently has a potassium-saving effect. It seems very useful in patients who become resistant the usual diuretics when it can be administered simultaneously with them. One has to be cautious about the renal and cerebral compli.
J. V. JOOSSENS R. VERWILGHEN R. VERBERCKMOES, TRAVELLERS’ DIARRHŒA
SIR,-Your interesting annotation (July 14) omits one of travellers’ diarrhoea which is immediately curable and may be numerically important-namely, giardiasis, I have diagnosed this infestation three times in colleagues troubled by persistent diarrhoea acquired abroad; in one the symptoms had come on suddenly in Rome three months before I saw him, and besides diarrhoea he had cause
and anorexia. The other two had had diarrhea a much longer time. Numerous present in the stools of two; in the third none could be found. All three were immediately cured by five days’ treatment with mepacrine. nausea
intermittently for trophozoites were
Medical Unit, Royal Infirmary, Cardiff.
DEMETHYLCHLORTETRACYCLINE AND GASTRIC CANCER of June 30 erroneous reference annotation SIR,-In your was made to my early work concerned with the localisation of brain tumours. The fluorescent properties of fluorescein were utilised for the recognition of brain tumours. Following intravenous injection of the dye, needle biopsy material was examined under an ultraviolet light. Brain tumour tissue was characterised by a brilliant yellow-green fluorescence. In our opinion this technique should be very helpful to the neurosurgeon and as an aid to the pathologist in choosing tissue fragments most likely to contain malignant cells for frozen sections. This work was summarised and illustrated with coloured photographs in a monograph.! Whereas it is our contention that there is some specific binding of this and related dyes to the nucleoproteins of malignant tissue, the localisation in brain tumours is primarily the result of disruption of the so-called bloodbrain barrier. Roswell Park Memorial Institute, Buffalo, New York.
GEORGE E. MOORE.
SiR,—I disagree with some of Dr. Kemp’s criticism fiberscope (July 14) and with his suggested modi-
fications. Like others, I have failed to introduce the tip of the instruinto the duodenum. But, even if this could be done, I doubt if the view obtained would be satisfactory; for the fiberscope, like the cystoscope, has a right-angled objective, excellent for examining the interior of relatively large cavities, but useless for looking down tubes. I have always thought that a gastrointestinal panendoscope should have a foreoblique viewing system, like its genitourinary counterpart. Having used the fiberscope for the past seven months, I now find that I can examine the stomach better with it than with the standard semirigid gastroscope. To stiffen the fiberscope 1. Diagnosis and Localization of Brain Tumors. Springfield, Ill., 1953.
During the whole period the patient was maintained in bed on a salt-free diet and received digitalis. The results are expressed as the mean of the daily values obtained during each period.