schizophrenia these druss
as well used.
in other clinical conditions where
NORMAL MEN, PLASMA FROZEN
T. HANSSEN T. HEYDEN I. SUNDBERG L. WETTERBERG
Department of Psychiatry, Karolinska Institute, St Göran’s Hospital, S-112 81 Stockholm, Sweden
CRYOACTIVATED C at -4’C
CRYOACTIVATED at -4° C
PROTEASE AS ENDOGENOUS ACTIVATOR OF INACTIVE RENIN
SIR,-Over the past year you have published several articles and letters
inactive renin in human plasma,’-’ the typical approach being to compare the concentration of inactive renin in plasma with that of active renin under various clinical and physiological conditions. Inactive renin seems to be an integral part of the renin-angiotensin system, a view that requires the existence of an endogenous activator, without which, inactive renin remains non-functional. Endogenous activators may exist in the kidney but plasma, because it contains so much inactive renin, has been the main focus. Most of your contributors activated inactive renin by acidifying plasma in vitro, generally by dialysis for 24 h at 40C against a buffer at pH 3.3, re-dialysis back to a higher pH, and then resupplying renin substrate before assaying renin activity at 37°C. The increment in renin activity was the measure of inactive renin. This procedure is far from physiological, and cannot prove that endogenous activation exists or, if it does, that low pH is essential. Two observations have combined to help us implicate endogenous protease(s) as the probable activator(s) of inactive renin. The first is cryoactivation of the plasma-renin system.7-9 Prolonged exposure of plasma to cold at non-acid pH activates inactive renin. Cryoactivation, while not physiological, does show that low pH is not essential for activation and it focuses attention on some mechanism triggered by cold. The second observation is that exogenous trypsin also activates inactive renin in plasma at normal pH and at 4, 23, or 37°,o,m proving that neither low pH nor cold are essential. If the potent protease inhibitors ’Trasylol’ (aprotinin, Bayer) and D.F.P. (diisopropylfluorophosphonate, Sigma) inhibit cryoactivation, this would strongly implicate one or more proteases. Blood from nine healthy men was anticoagulated with E.D.T.A. (ethylenediamine tetra-acetic acid) in the ammonium form.lo The plasma was treated with neomycin sulphate, 1 mg/ml. Two sets of four amounts of each plasma were prepared, each set containing a trasylol or a D.F.P. treated sample (only four of the plasmas were tested with D.F.P.) and two controls. Trasylol was added at 500 units/ml, and D.F.P. at 50 fLl/ml of a 1/20 dilution with isopropyl alcohol. The controls were treated with trasylol or D.F.P. solvents. One set of sealed tubes was kept frozen at -20°C (frozen control), the other at - 4°C in a temperature-controlled bath containing ethanol/ water (cryoactivated), in both cases for 72 h. The plasmas were now buffered to pH 6 and treated with angiotensinase inhibitors in preparation for incubation at 37°C.’" Samples were taken after 15, 30, and 60 min incubation, for 1.
2. 3. 4. 5.
Derkx, F. H. M., Wenting, G. J., Man in T Veld A. J., v.Gool J. M. G., Verhoeven R. P., Schalekamp M. A. D. H. Lancet, 1976, ii, 496. Leckie B, Lever, A. F., Morton, J. J., Brown, J. J., McConnell, A., Robertson, J. I. S., Tree, M. ibid. p. 748. Swales, J. D. ibid. p. 849. Amery A., Lijnen, P., Fagard, R., Reybrouck, T. ibid.; p. 849. Leckie, B., Brown, J. J., Lever, A. F., Morton, J. J., Robertson, J. I. S., Tree,
M. ibid, p. 1412. 6. Boyd, G. W. Lancet, 1977, i, 215. 7. Atlas, S. A., Laragh, J. H., Sealey, J. E., Moon, C. ibid. 1977, ii, 785. 8. Osmond, D. H., Ross, L. J., Scaiff, K. D. Can. J. Physiol. Pharmac.
51, 705. 9. Sealey, J. E., Moon, C., Laragh, J. H., Alderman,
Am. J. Med. 1976, 61,
Cooper, R. M., Murray, Suppl. no. 1., p. 171.
H. Circulation Res.
Cryoactivation of the plasma-renin system and its inhibition by Trasylol and D.F.P. Values as mean +
in normal men,
radioimmunoassay of angiotensin i, using reagents from the England Nuclear Biomedical Assay Laboratories, Boston.lO,12 Two values representing the linear portion of the generation curve were averaged in computing the net genera-
tion-rate in ng angiotensin/ml plasma/h. The results (see figure) show that in the frozen control plasmas, neither trasylol nor D.F.P. altered the normal rate of angiotensin generation at 37°C. Cryoactivation at -4°C resulted in enhanced angiotensin production at 37°C. The presence of trasylol or D.F.P. during cold exposure prevented most of the expected cryoactivation, inhibition being greater with D.F.P. This suggests that endogenous protease(s) was involved in the process of cryoactivation, having been present in plasma from the outset or somehow induced (de-inhibited?) by cold exposure. Thus, actually or potentially, there is endogenous protease activity in human plasma, capable of activating inactive renin in the cold. This evidence probably brings us closer to the endogenous activator operative at normal body temperature. Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario, Canada M5S 1A8
D. H. USMOND A. Y. LOH
MUNCHAUSEN SYNDROME BY PROXY
SiR,-Shortly after Meadow’s description of two children who were investigated for symptoms and signs fabricated by their mothers,’ we had to contend with a similar problem. A 3-year-old girl was referred with hsmaturia. Physical examination was normal. Initially her urine contained hsemoglobin and 4 2 % glucose, but no red blood-cells. Occasional urine cultures showed significant bacteriuria with mixed growths, 11. Osmond, D. H., Cooper, R. M. Unpublished. 12. Osmond, D. H., McFadzean, P. A., Scaiff, K. D. Clin. Biochem. 1974, 7, 52. 1. Meadow, R. Lancet, 1977, ii, 343.
urine taken by suprapubic aspiration was normal. renal function, blood-sugar, urography, and renal scan were normal. The "illness" then became more complex with low-grade fever, intermittent systolic hypertension and red blood-cells in the urine. Her haemoglobin suddenly fell from 12-3 to 7.0 g/dl without pallor, overt gastrointestinal bleeding, or evidence of hxmolysis. The white-blood-cell count almost halved and the mean red corpuscular volume rose from 78 to 91 fl. There was no reticulocytosis. A barium meal and enema were normal and her mother subsequently produced a stool, well-mixed with small amounts of fresh blood said to have been passed by the child. Despite our obvious uncertainty the mother was very patient, interested, and embarrassingly calm. We planned more invasive investigation, but then established that observations were being charted when no nurse had made them, and on review we could not exclude the possibility that urine or blood samples had been tampered with in the sluice room or on the porter’s collection tray. Any observations by senior nursing or medical staff were always normal. Analysis of a further urine sample showed that the red blood-cells were group B (mother’s blood-group); her daughter was group A. When confronted, the child’s mother was relieved at our discovery and admitted to writing false observations in the nurses’ charts, diluting blood-samples, and adding blood and sugar to the child’s urine and stool samples. Her daughter was very precious to her; she continually suspected illness, and this was her way of obtaining thorough investigation. The child was conceived when the mother was taking clomiphene for infertility, and the birth was premature. Common to Meadow’s first patient and ours were the use of a fertility drug, apparent maternal calm despite diagnostic delay, and overinvestigation of symptoms referable to the urinary tract. Our patient first presented soon after Meadow’s description, which was widely publicised. We have not been able to establish whether her mother was aware of this. She has accented ioint nsvchiatric and oa’diatric sunervision. one
or sceptical patients wanted to discontinue treatment before 90 min, because they were bored. They needed encouragement to continue to the end. Future studies will determine if the treatment-time can be shortened.
I thank Dr Sara
Pisanty for help
Department of Oral Medicine, Hebrew University-Hadassah Medical School, P.O. Box 1172, Jerusalem, Israel
SERUM-FERRITIN IN DIAGNOSIS OF HÆMOCHROMATOSIS
SiR,-Dr Leyland and colleagues (Nov. 12, p. 1030) have
reported that serum-ferritin values fluctuated widely in five patients with primary haemochromatosis undergoing venesection. Their data show a tendency for an initial sharp rise (as high as eight-fold) in serum-ferritin, with further significant fluctuations during the course of therapy. Although we have not encountered variation of this magnitude in our hsmochromatosis patients, we have recorded paradoxical rises in serum-ferritin concentration (up to two-fold in two patients) 1-2 months after the start of venesection. We venesect our patients at the rate of 600 ml twice a week. The serum-ferritin pool consists of several isoferritins. Since the antibody used in the immunoradiometric assay (I.R.M.A.) is raised against liver or spleen ferritin its affinity to a heterogeneous pool of isoferritins may be difficult.’ Thus, I.R.M.A. may underestimate serum-ferritin. This has been shown by Drysdale et al.2 in hyperferritinwmia secondary to cancer. We, too, have noted that I.R.M.A. underestimates serum-ferritin in haemochromatosis and other conditions of hyperferritinxmia 1. Green, R., Saab, G. A., Watson, L. R., Crosby, W. H. Blood, 2. Hazard, J. T., Drysdale, J. W. Nature, 1977, 265, 755.
1976, 48, 990.
P. T. CLAYTON R. COUNAHAN C. CHANTLER
Department of Pædiatrics, Guy’s Hospital Medical School, London SE1 9RT
ICE-PACKS FOR COLD-SORES
SIR,-I have obtained encouraging results after treating
herpes labialis by the application of ice-cubes. Treatconsists of one continuous application for 90-120 min. It must be done within 24 h of onset of the prodrome, the sooner the better. Prodromal symptoms and/or pain cease immediately-i.e., lip sensation returns minutes after therapy; but symptoms are no longer present. By the following day vesicles are reabsorbed without breaking or becoming purulent and healing is complete within 1 or 2 days. Fourteen cases were treated in the manner described. There were no treatment failures. All lesions were localised, without secondary manifestations. Therapy did not damage surrounding tissue. Four additional cases were treated 36 h or more after onset. In this group the therapy had little or no effect. Successful treatment does not prevent recurrence. In the literature I have found little mention of the successful use of cryotherapy. Is this because for most types of cryotherapy the patient must attend hospital or a clinic? If cryotherapy requires very early application for success, as suggested by my results and by Gheorghiu,l perhaps practitioners have seldom seen or treated patients early enough. Cryotherapy with ice-cubes lends itself to immediate selftreatment by the patient, being in effect a "home remedy". Patients can be instructed to recognise the prodrome, early signs and symptoms, and how to apply treatment. A minor practical problem in therapy was that some firstrecurrent ment
I. Derm. Vener
(Bucharest), 1965, 10,
antibody in haemochromatosis and other diseases. Bound antibody (%) shows ferritin-antiferritin complex expressed as a percentage of the total radiolabelled antibody which was added to 100 ng serum-ferritin determined by I.R.M.A. The percentage binding obtained with 100 ng assayable liver or serum-ferritin is shown by the horizontal lines. Bound and free antibody are separated by elution through column of biogel (A 0-5m). Bound