343 individuals were injected with the dose of DAMME the different responses are clearly due to greater sensitivity to enkephalin in the C.P.A.F.positive subjects. Nevertheless everyone injected with DAMME showed some rise in skin temperature and the same was true on testing for C.P.A.F. The tendency to flush, therefore, is one of degree. Enkephalins are pentapeptides and their sequence is contained within a larger peptide, &bgr;-endorphin, which in turn is a 31-aminoacid residue of the peptide p-lipotrophin. These peptides have opiate-like activity which could be responsible for their widespread metabolic effects.3,4 It is likely that other peptides with opiate-like activity have the same effect on facial flushing as enkephalin. Just how the interaction of chlorpropamide and alcohol produces opiate-like activity is unclear. Alcohol itself may have some opiate-like activity since alcoholic coma can be reversed by naloxone.5 Furthermore alcohol affects cerebral calcium in the same manner as does morphine and this effect can also be reversed by naloxand
c.P.A.F.-negative
same
one.6
and, by implication, enkephalin sensitivity, is inherited trait which occurs in about 90% of noninsulin dependent diabetics with a strong family history of diabetes.2 Does enkephalin sensitivity actually cause this type of diabetes? There are several reasons for considering that sensitivity to enkephalins, and other peptides with opiate-like activity, might do so. Morphine has long been known to cause hyperglycxmia and to do so through a central effect.’ Blood-glucose increases by at least 8 mmol/1 after intraventricular injection of morphine or &bgr;endorphin. Though this effect is thought to be due to sympathetic discharge it differs from the hyperglycaemia resulting from intraventricular administration of adrenalin both in the site of action on the ventral surface of the brain-stem and in being abolished by anxsthesia.8,9 Opiate receptors are widely but unevenly distributed in the brain10 and the effects of opiate-like peptides on neuronal activity suggest they play an important role in neurotransmission." It is particularly interesting that insulin,12 insulin receptors," and somatostatin" are also widely distributed in the brain, with localisation similar to that of opiate receptors. These observations provide a basis for extensive central regulation of insulin by opiate-like peptides. There is now considerable evidence that peptides found in the brain also occur in the gastrointestinal tract. Both opiate-like peptides and opiate receptors have been found in high concentration in the gut. 15 Since immunoreactive enkephalin has also been found in the pancreas" opiates might act peripherally as well as centrally. We know that other neuropeptides such as C.P.A.F.,
an
P, bombesin, and neurotensin cause hyperglycaemia through a peripheral effectY-19 Opiates substance
increase insulin and glucagon in the isolated dog pancreas." Present evidence therefore indicates widespread opiate-mediated effects on glucose homeostasis. Intravenous DAMME, the enkephalin analogue, slightly decreases blood-glucose in normal subjects.4 We observed this in both diabetics and non-diabetics but the diabetics were on treatment which could have affected the results. L’nhke insulin-dependent diabetes the pancreas in noninsulin-dependent diabetes may be histologically normal and serum-insulin levels can be variable, even high. The
dependent diabetes is unknown. sensitivity to enkephalin in certain non-insulin-dependent diabetics strongly suggests an opiate-mediated effect in the genesis of this disease. If this view is correct it is, we think, the first demonstration of a role for enkephalin and other peptides with opiate-like activity in the aetiology of an organic disease.
cause
of non-insulin
However, increased
We thank Dr B. von Graffenried of Sandoz (Basel) for supplies of and Messrs Winthrop for a gift of naloxone. We thank Prof. H. Keen and Prof. R. H. T. Edwards for helpful discussion and comments. R. D. G. L. is supported by the Medical Research Council. DAMME
Requests for reprints should be addressed to R. D. G. L. REFERENCES 1. Leslie, R. D. G., Pyke, D. A. Br. med. J. 1978, ii, 1519. 2. Pyke, D. A., Leslie, R. D. G. ibid. p. 1521. 3. von Graffenried, B., del Pozo, E., Rowbieck, J., Krebbs, E., Poldinger, W., Burmeister, P., Kemp, L. Nature, 1978, 272, 729. 4. Stubbs, W. A., Delitala, G., Jones, A., Jeffcoate, W. J., Edwards, C. R. W., Ratter, S. S., Besser, G. M., Bloom, S. R., Alberti, K. G. M. M. Lancet,
1978, ii, 1225. 5. Sorensen, S. C., Mattison, K. W. ibid. p. 688. 6. Ross, D. H.Ann.N.Y.Acad. Sci. 1976, 273, 280. 7. Borison, H. L., Fishburn, B. R., Bhide, N. K., McCarthy, L. E. J. Pharmac. exp. Therap. 1962, 138, 229. 8. Feldberg, W. Neuroscience, 1976, 1, 427. 9. Feldberg, W., Smyth, D. G. Br. J. Pharmac. 1977, 60, 445. 10. Cuello, A. C. Lancet, 1978, ii, 291. 11. Nicoll, R., Siggins, G., Ling, N., Bloom, F., Guillemin, R. Proc. natn. Acad.
Sci. U.S.A., 1977, 74, 2584. 12. Havrankova, J., Schmechel, D., Roth, J., Brownstein, M. Unpublished. 13. Havrankova, J., Roth, J., Brownstein, M. Nature, 1978, 272, 827. 14. Petrusz, P., Sar, M., Grossman, G. H., Kizer, J. S. Brain Res. 1977, 137, 181. 15. Pert, C. B., Snyder, S. H. Science, 1973, 179, 1101. 16. Forsmann, W. G., Helmsaedter, V., Feurie, G. Acta hepatogastroent. 1977,
24, 488. 17. Brown, M., Vale, W. Endocrinology, 1976, 98, 18. Brown, M., Rivier, J., Vale, W. Unpublished 19. 20.
819.
(cited in Metabolism, 1978, 9,
1253). Nagai, K., Frohman, L. Life Sci. 1978, 19, 273. Ipp, E., Dobbs, R., Unger, R. H. Nature, 1978, 276, 190.
SELECTIVITY AS A CLUE TO DIAGNOSIS OF POSTURAL PROTEINURIA BRIGITTE M. FREY* FELIX J. FREY* ROLF KOEGEL JUERG HODLER EDGAR WEGMUELLER Unit of Clinical Pathology, Medical Outpatient Department, University Hospital, Berne, Switzerland
In 14 patients with fixed and reproducible postural proteinuria and 14 patients with histologically proven glomerulonephritis, the selectivity of proteinuria was measured separately in the day and night urine collections. The selectivity of proteinuria in the urine collected in recumbency was lower in patients with glomerulonephritis than in patients with postural proteinuria. All patients with postural proteinuria showed an increment of the selectivity from day to night of at least 13°, whereas the maximum increment in patients with glomerulonephritis was 5°. The changes in selectivity from day to night in patients with postural proteinuria and patients with glomerulonephritis were significantly different and seem to be a useful discri-
Summary
minatory test. * Present address: School of Medicine, Department of California, San Francisco, California, U.S.A.
Medicine, University of
344
Introduction
TABLE I——CHANGES IN SELECTIVITY AND PROTEIN EXCRETION IN PATIENTS WITH POSTURAL PROTEINURIA
and therapeutic reasons it is important to differentiate proteinuria due to glomerulonephritis from so-called "postural proteinuria" .1-3 Glomerulonephritis may mimic postural proteinuria if the degree of proteinuria is small and if there is a difference between the amount of protein excreted during the day and night. In addition, protein excretion of patients with postural proteinuria may be quite heavy (>2g/day) in the upright position, suggesting the diagnosis of glomerulonephritis. Renal biopsy is often done to establish the mechanism of protein loss in individual cases. A noninvasive test for the diagnosis of postural proteinuria would therefore be useful. This report presents preliminary evidence that measurement of the selectivity of proteinuria in the upright and recumbent positions might be a valuable diagnostic procedure. FOR
prognostic
Patients and Methods 8 male and 6 female patients, aged 9 to 32 years, with fixed and reproducible postural proteinuria were observed for 3 to 78 months. They were selected on the following criteria: proteinuria recumbent of less than 30 mg/dl (semiquantitative trace protein reaction) and of more than 30 mg/dl upright; normal glomerular-filtration rate and urinary sediment. In all the erythrocyte-sedimentation rate, serum-cholesterol, and C3 levels were within normal limits. 9 male and 5 female patients, aged 12 to 72 years, with biopsy-proven glomerulonephritis were studied concurrently. An 8-15 hour urine collection was made during the day while the patient was upright with normal activity. 30 min after the patient had lain down he was
TABLE H——CHANGES IN SELECTIVITY AND PROTEIN EXCRETION IN PATIENTS WITH GLOMERULONEPHRITIS
I
’
3
o
asked to void, and the urine obtained during this period was added to the first collection. The collection was then continued for at least 8 h of recumbency. At the end of the second collection a venous-blood sample was drawn for serum protein, cholesterol, and C3 determinations. Individual protein concentrations in plasma and urine were estimated immunochemically by a modification of Laurell’s method.4-6 Clearances of albumin, transferrin, haptoglobin, and &agr;2-macroglobulin were calculated. The clearance of each protein was expressed as a percentage of the albumin clearance. The relative clearances were plotted against the respective molecular weight on a double logarithmic scale. The selectivity was expressed by the angle of the linear-regression line.7 The total protein in the urine was measured with Rice’s method.8 Statistical analysis was by the non-parametric Wilcoxon test.
Results o
Selectivity of proteinuria in upright (day) and recumbent (night) position in 14 patients with postural (orthostatic) proteinuria and 14 patients with glomerulonephritis.
The accompanying figure shows the change of the selectivity angle of proteinuria from day to night for both groups of patients. All patients with postural proteinuria had an increment of the selectivity from day to night of at least 13°, whereas most of the patients with glomerulonephritis had no change in selectivity, the maximum increment being 50. These differences between the groups were statistically significant (P
c.P.A.F.-negative
same
one.6
and, by implication, enkephalin sensitivity, is inherited trait which occurs in about 90% of noninsulin dependent diabetics with a strong family history of diabetes.2 Does enkephalin sensitivity actually cause this type of diabetes? There are several reasons for considering that sensitivity to enkephalins, and other peptides with opiate-like activity, might do so. Morphine has long been known to cause hyperglycxmia and to do so through a central effect.’ Blood-glucose increases by at least 8 mmol/1 after intraventricular injection of morphine or &bgr;endorphin. Though this effect is thought to be due to sympathetic discharge it differs from the hyperglycaemia resulting from intraventricular administration of adrenalin both in the site of action on the ventral surface of the brain-stem and in being abolished by anxsthesia.8,9 Opiate receptors are widely but unevenly distributed in the brain10 and the effects of opiate-like peptides on neuronal activity suggest they play an important role in neurotransmission." It is particularly interesting that insulin,12 insulin receptors," and somatostatin" are also widely distributed in the brain, with localisation similar to that of opiate receptors. These observations provide a basis for extensive central regulation of insulin by opiate-like peptides. There is now considerable evidence that peptides found in the brain also occur in the gastrointestinal tract. Both opiate-like peptides and opiate receptors have been found in high concentration in the gut. 15 Since immunoreactive enkephalin has also been found in the pancreas" opiates might act peripherally as well as centrally. We know that other neuropeptides such as C.P.A.F.,
an
P, bombesin, and neurotensin cause hyperglycaemia through a peripheral effectY-19 Opiates substance
increase insulin and glucagon in the isolated dog pancreas." Present evidence therefore indicates widespread opiate-mediated effects on glucose homeostasis. Intravenous DAMME, the enkephalin analogue, slightly decreases blood-glucose in normal subjects.4 We observed this in both diabetics and non-diabetics but the diabetics were on treatment which could have affected the results. L’nhke insulin-dependent diabetes the pancreas in noninsulin-dependent diabetes may be histologically normal and serum-insulin levels can be variable, even high. The
dependent diabetes is unknown. sensitivity to enkephalin in certain non-insulin-dependent diabetics strongly suggests an opiate-mediated effect in the genesis of this disease. If this view is correct it is, we think, the first demonstration of a role for enkephalin and other peptides with opiate-like activity in the aetiology of an organic disease.
cause
of non-insulin
However, increased
We thank Dr B. von Graffenried of Sandoz (Basel) for supplies of and Messrs Winthrop for a gift of naloxone. We thank Prof. H. Keen and Prof. R. H. T. Edwards for helpful discussion and comments. R. D. G. L. is supported by the Medical Research Council. DAMME
Requests for reprints should be addressed to R. D. G. L. REFERENCES 1. Leslie, R. D. G., Pyke, D. A. Br. med. J. 1978, ii, 1519. 2. Pyke, D. A., Leslie, R. D. G. ibid. p. 1521. 3. von Graffenried, B., del Pozo, E., Rowbieck, J., Krebbs, E., Poldinger, W., Burmeister, P., Kemp, L. Nature, 1978, 272, 729. 4. Stubbs, W. A., Delitala, G., Jones, A., Jeffcoate, W. J., Edwards, C. R. W., Ratter, S. S., Besser, G. M., Bloom, S. R., Alberti, K. G. M. M. Lancet,
1978, ii, 1225. 5. Sorensen, S. C., Mattison, K. W. ibid. p. 688. 6. Ross, D. H.Ann.N.Y.Acad. Sci. 1976, 273, 280. 7. Borison, H. L., Fishburn, B. R., Bhide, N. K., McCarthy, L. E. J. Pharmac. exp. Therap. 1962, 138, 229. 8. Feldberg, W. Neuroscience, 1976, 1, 427. 9. Feldberg, W., Smyth, D. G. Br. J. Pharmac. 1977, 60, 445. 10. Cuello, A. C. Lancet, 1978, ii, 291. 11. Nicoll, R., Siggins, G., Ling, N., Bloom, F., Guillemin, R. Proc. natn. Acad.
Sci. U.S.A., 1977, 74, 2584. 12. Havrankova, J., Schmechel, D., Roth, J., Brownstein, M. Unpublished. 13. Havrankova, J., Roth, J., Brownstein, M. Nature, 1978, 272, 827. 14. Petrusz, P., Sar, M., Grossman, G. H., Kizer, J. S. Brain Res. 1977, 137, 181. 15. Pert, C. B., Snyder, S. H. Science, 1973, 179, 1101. 16. Forsmann, W. G., Helmsaedter, V., Feurie, G. Acta hepatogastroent. 1977,
24, 488. 17. Brown, M., Vale, W. Endocrinology, 1976, 98, 18. Brown, M., Rivier, J., Vale, W. Unpublished 19. 20.
819.
(cited in Metabolism, 1978, 9,
1253). Nagai, K., Frohman, L. Life Sci. 1978, 19, 273. Ipp, E., Dobbs, R., Unger, R. H. Nature, 1978, 276, 190.
SELECTIVITY AS A CLUE TO DIAGNOSIS OF POSTURAL PROTEINURIA BRIGITTE M. FREY* FELIX J. FREY* ROLF KOEGEL JUERG HODLER EDGAR WEGMUELLER Unit of Clinical Pathology, Medical Outpatient Department, University Hospital, Berne, Switzerland
In 14 patients with fixed and reproducible postural proteinuria and 14 patients with histologically proven glomerulonephritis, the selectivity of proteinuria was measured separately in the day and night urine collections. The selectivity of proteinuria in the urine collected in recumbency was lower in patients with glomerulonephritis than in patients with postural proteinuria. All patients with postural proteinuria showed an increment of the selectivity from day to night of at least 13°, whereas the maximum increment in patients with glomerulonephritis was 5°. The changes in selectivity from day to night in patients with postural proteinuria and patients with glomerulonephritis were significantly different and seem to be a useful discri-
Summary
minatory test. * Present address: School of Medicine, Department of California, San Francisco, California, U.S.A.
Medicine, University of
344
Introduction
TABLE I——CHANGES IN SELECTIVITY AND PROTEIN EXCRETION IN PATIENTS WITH POSTURAL PROTEINURIA
and therapeutic reasons it is important to differentiate proteinuria due to glomerulonephritis from so-called "postural proteinuria" .1-3 Glomerulonephritis may mimic postural proteinuria if the degree of proteinuria is small and if there is a difference between the amount of protein excreted during the day and night. In addition, protein excretion of patients with postural proteinuria may be quite heavy (>2g/day) in the upright position, suggesting the diagnosis of glomerulonephritis. Renal biopsy is often done to establish the mechanism of protein loss in individual cases. A noninvasive test for the diagnosis of postural proteinuria would therefore be useful. This report presents preliminary evidence that measurement of the selectivity of proteinuria in the upright and recumbent positions might be a valuable diagnostic procedure. FOR
prognostic
Patients and Methods 8 male and 6 female patients, aged 9 to 32 years, with fixed and reproducible postural proteinuria were observed for 3 to 78 months. They were selected on the following criteria: proteinuria recumbent of less than 30 mg/dl (semiquantitative trace protein reaction) and of more than 30 mg/dl upright; normal glomerular-filtration rate and urinary sediment. In all the erythrocyte-sedimentation rate, serum-cholesterol, and C3 levels were within normal limits. 9 male and 5 female patients, aged 12 to 72 years, with biopsy-proven glomerulonephritis were studied concurrently. An 8-15 hour urine collection was made during the day while the patient was upright with normal activity. 30 min after the patient had lain down he was
TABLE H——CHANGES IN SELECTIVITY AND PROTEIN EXCRETION IN PATIENTS WITH GLOMERULONEPHRITIS
I
’
3
o
asked to void, and the urine obtained during this period was added to the first collection. The collection was then continued for at least 8 h of recumbency. At the end of the second collection a venous-blood sample was drawn for serum protein, cholesterol, and C3 determinations. Individual protein concentrations in plasma and urine were estimated immunochemically by a modification of Laurell’s method.4-6 Clearances of albumin, transferrin, haptoglobin, and &agr;2-macroglobulin were calculated. The clearance of each protein was expressed as a percentage of the albumin clearance. The relative clearances were plotted against the respective molecular weight on a double logarithmic scale. The selectivity was expressed by the angle of the linear-regression line.7 The total protein in the urine was measured with Rice’s method.8 Statistical analysis was by the non-parametric Wilcoxon test.
Results o
Selectivity of proteinuria in upright (day) and recumbent (night) position in 14 patients with postural (orthostatic) proteinuria and 14 patients with glomerulonephritis.
The accompanying figure shows the change of the selectivity angle of proteinuria from day to night for both groups of patients. All patients with postural proteinuria had an increment of the selectivity from day to night of at least 13°, whereas most of the patients with glomerulonephritis had no change in selectivity, the maximum increment being 50. These differences between the groups were statistically significant (P
