690 choactive polypeptides derived from wheat gluten) may be as easily postulated. We fully endorse the need for further study of the role of wheat gluten and related substances in schizophrenia, but do not think that the cause of scientific knowledge is best served by brushing aside data from careful independent investigations on the basis of hypothetical ideas. State of New York Department of Mental Bronx Psychiatric Center, Bronx, N.Y. 10461, U.S.A.
MAN MOHAN SINGH STANLEY R. KAY
Accordingly, we propose to monitor the E.c.G. systematically 1n patients receiving vinca alkaloids. G. SOMERS M. ABRAMOW M. WITTEK J. P. NAETS
Department of Medicine, Brugmann Hospital, University of Brussels (V.U.B.-U.L.B.), Brussels, Belgium
SIR,-Your editorial of Aug. 21 (p. 406) mentioned the detection of HBsAg as one of the applications of enzyme imMYOCARDIAL INFARCTION: A COMPLICATION OF VINCRISTINE TREATMENT?
SIR,-Weinstein et al.’ have described the case of a 27-yearold man who experienced three separate episodes of chest pain, each occurring on the 6th day ofM.o.p.p. combination chemotherapy (nitrogen mustard 12 mg, vincristine 2 mg, procarbazine 200 mg, prednisone 80 mg). The first episode was caused by myocardial infarction, but no characteristic lesion could be demonstrated in the next two episodes. Since the patient had been treated by mediastinal irradiation a year before, the authors suggested the possibility of a causal relation between myocardial infarction and chemotherapy after cardiac irradiation. Mandel et al. described a patient with lymphosarcoma, treated with high doses of vincristine (0.11 mg/kg body-weight), who presented two episodes of myocardial infarction, each time closely related to administration of the drug. We have observed another case of myocardial infarction associated with vincristine treatment. A 73-year-old woman was admitted to hospital in a cachectic state. She had no previous history of coronary disease. The diagnosis of reticulum-cell sarcoma was established on examination of a biopsy specimen of a left supraclavicular lymphnode and the finding of an epigastric tumour infiltrating the stomach. Haemoglobin level averaged 13 g/dl and remained unchanged during the course of disease and treatment. Plateletcount was 450 000. White-cell count was 20 000 (neutrophils 85%, no abnormal cells noted). Myelogram showed only
granulocytic hyperplasia. The patient was given a single intravenous injection of vincristine (0-03 mg/kg body-weight) and nitrogen mustard (0-1 mg/kg body-weight). Prednisone (60 mg/day) and methylhydrazine (150 mg/day) were given orally for 2 wk. 3 days after the vincristine injection the patient complained of severe precordial pain, radiating to the back and neck and resistant to morphine. An electrocardiogram (E.C.G.) which had been normal on admission revealed signs of acute diaphragmatic infarction. Blood-enzymes (creatine phosphokinase, lactic dehydrogenase, glutamic oxaloacetic transaminase) were above normal. A second identical dose of vincristine was given a week after the first injection, without nitrogen mustard. The same precordial symptoms recurred 2 days later, and this time electrocardiographic signs of anteroseptal subendocardial injury were present. The patient became progressively weaker and died 3 wk after the second episode of retrosternal pain. Unfortunately no
The striking coincidence between vincristine administration, symptoms, and objective evidence of myocardial lesion led us to believe that the vinca alkaloid could be incriminated, as already suggested by Mandel et al. Our patient and the patient described by Weinstein et al.were treated with relatively small doses of vincristine. Mediastinal irradiation was not performed before chemotherapy, either in our case or in Mandel’s. We agree with these authors that vincristine probably causes changes in an atherosclerotic coronary vessel or anoxic myocardium, thereby precipitating acute myocardial lesion. 1. 2.
Weinstein, P., Greenwald, E. S., Grossman, J. Am. J. Med. 1976, 60, 152. Mandel, E. M., Lewinski, U. D., Jaldelti, M. Cancer, N.Y. 1975, 36, 1979.
munoassay, but cited no references. On the basis of earlier work on enzyme immunoassay in our group’ we developed such a test for HBsAg. Our first results were presented at the Biochemische Analytik in Munich in ApriP and a full report will appear elsewhere.3 We found that the solid-phase enzyme-immunoassay, which we developed on the sandwich principle in microtitre plates, has about the same sensitivity as the radioimmunoassay. The detection limit was estimated at 5-10 ng/ml of HBsAg or even lower, for both subtypes ad and ay. A multicentre trial of this test in sixteen European centres was completed this summer for about 65 000 samples. The results will be published. The data support our earlier finding that the enzyme immunoassay can compete with radioimmunoassay in sensitivity.
Organon Scientific Development Group, Oss, Netherlands
G. WOLTERS L. P. C. KUIJPERS J. KACAKI A. H. W. M. SCHUURS
QUALITY CONTROL OF ’DEXTROSTIX’
SIR,- The use of ’Dextrostix’ reagent strips in the diagnosis of hypoglycxmia is a rapid reliable test only if they are used correctly. The main reason for their failure, and hence a reputation for unreliability, is that once the bottle is opened they deteriorate. In ordinary weather they last about five weeks from the time of opening, but in the recent hot weather they have tended to under-read after one week, even with the lid firmly replaced after each use. Accuracy at the low end of the scale is important if patients with hypoglycaemic seizures or unconsciousness are to be correctly diagnosed. Clearly some form of quality control at the time of use is required. Pricking one’s own finger to provide a control is feasible and I have used this successfully. However, a very simple alternative is suggested here. Dextrostix do not read correctly with standard solutions of glucose since they are designed to work on blood. However, a 2.5 mmol/1 solution of glucose in saturated sodium benzoate consistently reads 90 mg/dl (or 5 mmol/1) on a dextrostix. Therefore a distinct blue rather than buff or grey colour is achieved. It is important to read the centre of the strip as sometimes the edges take up more solution. This solution should easily be available from the chemical-pathology laboratory as it is a likely reference standard for any autoanalyser technique measuring glucose levels. The sodium benzoate is used as a teriorate.
I recommend, therefore, that with each bottle of dextrostix is issued a small quantity (5 ml) of 2.5 mmol/1 glucose in saturated sodium benzoate. At the time of estimating a patient’s blood-glucose another dextrostix is dipped in this solution for 1 s, held horizontal to keep the fluid on the reactive area, flicked off at 1 min, and read at 75 s, after which there is little more colour change. This colour change will also give a read1. Weeman, B. K., van, Schuurs, A. H. W. M. F.E.B.S. Lett. 1971 15, 232, ibid. 1972, 24, 77; ibid. 1974, 43, 215. 2. Wolters, G., Kuijpers, L. P. C., Schuurs, A. H. W. M., Kaćaki, J Z. Analyt. Chem. 1976, 279, 144. 3. Wolters, G., Kuijpers, L., Kacaki, J., Schuurs, A. J. clin. Path. in the press