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Pathogenesis of Leigh's encephalomyelopathy
Volume 81 Number 1
Letters to the Editor
L. W.: Use of carbenicillin in patients with cystic fibrosis, J. Infect. Dis. 122: 59, 1970. (Suppl.) 4. Boxerbaum, B., Pittman, S., Doershuk, C. F., Stern, R. C., and Matthews, L. W.: Use of gentamicin in children with cystic fibrosis, J. Infect. Dis. 124: 293, 1971. (Suppl.)
Table I. Activity of pyruvate carboxylase in livers of rat, control subjects, and patients
Source
_Patbogenesisof Leigb's encepbalomyelopatby* To the Editor: Since Leigh1 first described a case of subacute necrotizing encephalomyelopathy in an infant in 1951, more than 65 cases of this disease have been reported. 2 Its pathogenesis has never been well defined. Two schools of thought are emerging. One postulates an inborn error of pyruvate metabolism,3, 4 culminated by the study of Hommes and associates, 5 who demonstrated a deficiency of pyruvate carboxylase. The other, represented by Cooper and associates 6, ~ and Pincus and associates, s emphasizes thiamine triphosphate deficiency in the central nervous system, attributed to inhibitory factors in the body fluids. Both schools do not appear to be See related article, p. 39. mutually exclusive, and both feel that one of the factors involved in pyruvate oxidation, lipoic acid or thiamine, may be of some value in the treatment of this disease. We are currently studying the case of a 4month-old female infant, who is thought to have Leigh's encephalomyelopathy because a sib died of this disease, proved on autopsy, and she herself displayed apathy, inactivity, persistent Moro reflex, and generalized spasticity. Urine was found inhibitory to thiamine pyrophosphate-ATP phosphotransferase. Blood lactic acid was 78 mg. per cent (normal upper limit, 12 mg. per cent), and blood pyruvic acid, 1.7 mg. per cent (normal upper limit, 0.7 mg. per cent). Serum cholesterol was unusually low, 97 mg. per cent. No anemia was noted. The enzymatic assay of a liver biopsy revealed that no pyruvate carboxylase activity was present in the mitochondria in spite of the fact that an excess of these organelles had been ~The enzyme research was supported by a grant of National Institutes o[ Health, No. AM-10-334, and the clinical investigation by a Jeannette MeKelvey research [ellowship.
1 89
Adult rat liver Human control subject (2-monthold infant) Patient Literature control values5 14-day-old infant 1-year-old infant
Activity* (#moles/ min./Gm. o[ wet tissue) 5.1 3.7 < 0.1"~ 2.1 6.2
~Mitochondria were prepared from fresh liver samples as described by Johnson and Lardy9 and assayed after freeze drying according to the procedure of McClure and associates. 10 tNo activity could be detected within the limits of the assay.
observed in the same specimen under the electronmicroscope (Table I). Thus we confirm the observation of Hommes and associates 5 that there is a deficiency of pyruvate carboxylase in Leigh's encephalomyelopathy, but we do not share the interpretation that the impaired gluconeogenesis would be the sole mechanism of this disease. We believe that an ineffectively operated Krebs trlcarboxylic acid cycle due to oxaloacetate deficiency may also play an important role in the pathogenesis. I n an attempt to supply the 4-carbon dicarboxylic acid continually and minimize the demand on gluconeogenesis, the formula was supplemented with L-glutamine, and the frequency of feeding was increased. Large doses of vitamin B~ were given to insure maximal rate of transamination. After two weeks' feeding with formulas containing 150 mg. of L-glutamine once every three hours, and vitamin Bs, 25 mg. four times a day, the infant became more alert and active, and less hypertonic, began to roll over from the prone to supine position, and had better head control. The mother was most impressed by her baby's improvement. The infant now appears to be thriving, and shows no sign of deterioration. Blood lactic acid has been lowered to 30 mg. per cent, blood pyruvic acid to 1.1 mg. per cent, and serum cholesterol elevated to 135 mg. per cent. Serum serine has been lowered from 52 #moles per cent to 12 #moles per cent, and serum asparagine elevated from none to 87 #moles per cent. The panorama of these biochemical changes seem to be appropriately explicable on the basis
1 90
Letters to the Editor
that uninterrupted sources of 4-carbon dicarboxylic acids for the Krebs cycle have been provided by frequent feedings, and by vitamin B6 through its versatile coenzymatic activities, including transamination and conversion of glutamate to a-ketoglutarate, and aspartate to oxaloacetate, and decarboxylation of glutamate to y-aminobutyrate and then succinate, a metabolic pathway specific to the central nervous system. With the intermediates thus replenished and the blockage of pyruvate carboxylation Obviated, the Krebs cycle is again able to utilize pyruvic acid, and subsequently to lower lactic acid, and serine levels in blood, and facilitate the synthesis of cholesterol. The remarkable increase of serum asparagine further demonstrates the improved efficiency and Krebs cycle in converting L-glutamine to L-asparagine via a-ketoglutarate, and oxaloacetate. In summary, we have found the deficiency of mitochondrial pyruvate carboxylase with pleoconia in liver tissue of our study very significant, and the favorable response of our patient to frequent feedings and vitamin Bs most interesting. Being aware of the brevity and paucity of our clinical experience with Leigh's encephalomyelopathy, we wish to share it by this letter in order to continue to remodel our thoughts on this disease. The urine assay for inhibitory factor was done by Dr. Jack R. Cooper, Yale University School of Medicine.
Thomas T. Tang, Ph.D., M.D. Thomas A. Good, M.D. Paul R. Dyken, M.D. Stanley D. ]ohnsen, M.D. Samuel R. McCreadie, M.D. Santiago T. Sy, M.D. Milwaukee Children's Hospital Milwaukee, Wis. 53233 Henry A. Lardy, Ph.D. Frederick B. Rudolph, Ph.D. Institute for Enzyme Research University of Wisconsin Madison, Wis. 53706 REFERENCES 1. Leigh, D.: Subaeute ne~rotlzing encephalomyelopathy in an ~ J. Neurol. Neurosurg. Psychiatr. 14: 216, 1951. 2. Montpetit, V. J. A., Andermann, F., Carpenter, S., Fawcett, .J.S., Zborowskasluis, 13., and Giberson, H. R.: Subaeute necrotizing encephaIomyeIopathy. A review and a study of two families, Brain 94: I, 1971. 3. Ebels, E. J., Blokzijl, and Troelstra, J. A.: A Wernicke-like encephalomyelopathy in chil-
The Journal o[ Pediatrics July 1972
4.
5.
6.
7.
8.
9.
i0.
dren (Leigh), an inborn error of metabolism ? Report of 5 cases with emphasis on its familial incidence, Helv. Pediatr. Acta 3: 310, 1965. Clayton, B. E., Dobbs, R. H., and Patrick, A. D.: Leigh's subacute necrotizing eneephalopathy: Clinical and biochemical study with special reference to therapy with lipoate, Arch. Dis. Child. 42: 467, 1966. Hommes, F. A., Polman, H. A., and Reenink, J. D.: Leigh's encephalomyelopathy: An inborn error of gluconeogenesis, Arch. Dis. Child. 43: 423, 1968. Cooper, J. R., Itokawa, Y., and Pincus, J. H.: Thiamine triphosphate deficiency in subacute necrotizing encephalomyelopathy, Science 164: 72, 1969. Cooper, J. R., Pincus, J. H., Itokawa, Y., and Piros, K.: Experience with phosphoryl transferase inhibition in subacute necrotizing encephalomyelopathy, N. Engl. J. Med. 283: 793, 1970. Pincus, H. J., Cooper, J. R., Itokawa, Y., and Gumbinas, M.: Subacute neerotizing encephalomyelopathy, Arch. Neurol. 24: 511, 1971. Johnson, D., and Lardy, H. A.: In Colowlch, S. P., and Kaplan, N. O.: editors: Methods in enzymology, New York, 1967, Academic Press, Inc., p. 94. McClure, W. R., Lardy, H. A., and Kneifel, H. P.: Rat liver pyruvate carboxylase, preparation, properties, and cation specificity, J. Biol. Chem. 246: 3569, 1971.
Intravenous alimentation To the Editor: The article "Intravenous alimentation in pediatric patients," by Heird and associates 1 is a scholarly review of an important medical development. While the discussions are eminently educational, we believe the authors have overemphasized the dependence on central veins in contrast to the peripheral vein for parenteral nutrition in the small infant. Their terms "mandatory" and "imperative" for hyperosmolar solutions to be given by large veins has not been our experiences or that of others, s, 4 While use of the central vein is necessary in the large infant for administration of adequate calories, peripheral veins are quite satisfactory and less hazardous for parenteral nutrition of the infant under 2 Kg. The slower flow rates and reduced concentration of protein and glucose advisable for the more immature infant allow the use of smaller veins and still promote growth. Our current solutions contains approximately 65 calories per i00 mI. (2 per cent protein hydrolysate, 10 to 13 per cent glucose, 1.5 per cent ethyl alcohol) and can be given at flow rates in
Letters to the Editor
L. W.: Use of carbenicillin in patients with cystic fibrosis, J. Infect. Dis. 122: 59, 1970. (Suppl.) 4. Boxerbaum, B., Pittman, S., Doershuk, C. F., Stern, R. C., and Matthews, L. W.: Use of gentamicin in children with cystic fibrosis, J. Infect. Dis. 124: 293, 1971. (Suppl.)
Table I. Activity of pyruvate carboxylase in livers of rat, control subjects, and patients
Source
_Patbogenesisof Leigb's encepbalomyelopatby* To the Editor: Since Leigh1 first described a case of subacute necrotizing encephalomyelopathy in an infant in 1951, more than 65 cases of this disease have been reported. 2 Its pathogenesis has never been well defined. Two schools of thought are emerging. One postulates an inborn error of pyruvate metabolism,3, 4 culminated by the study of Hommes and associates, 5 who demonstrated a deficiency of pyruvate carboxylase. The other, represented by Cooper and associates 6, ~ and Pincus and associates, s emphasizes thiamine triphosphate deficiency in the central nervous system, attributed to inhibitory factors in the body fluids. Both schools do not appear to be See related article, p. 39. mutually exclusive, and both feel that one of the factors involved in pyruvate oxidation, lipoic acid or thiamine, may be of some value in the treatment of this disease. We are currently studying the case of a 4month-old female infant, who is thought to have Leigh's encephalomyelopathy because a sib died of this disease, proved on autopsy, and she herself displayed apathy, inactivity, persistent Moro reflex, and generalized spasticity. Urine was found inhibitory to thiamine pyrophosphate-ATP phosphotransferase. Blood lactic acid was 78 mg. per cent (normal upper limit, 12 mg. per cent), and blood pyruvic acid, 1.7 mg. per cent (normal upper limit, 0.7 mg. per cent). Serum cholesterol was unusually low, 97 mg. per cent. No anemia was noted. The enzymatic assay of a liver biopsy revealed that no pyruvate carboxylase activity was present in the mitochondria in spite of the fact that an excess of these organelles had been ~The enzyme research was supported by a grant of National Institutes o[ Health, No. AM-10-334, and the clinical investigation by a Jeannette MeKelvey research [ellowship.
1 89
Adult rat liver Human control subject (2-monthold infant) Patient Literature control values5 14-day-old infant 1-year-old infant
Activity* (#moles/ min./Gm. o[ wet tissue) 5.1 3.7 < 0.1"~ 2.1 6.2
~Mitochondria were prepared from fresh liver samples as described by Johnson and Lardy9 and assayed after freeze drying according to the procedure of McClure and associates. 10 tNo activity could be detected within the limits of the assay.
observed in the same specimen under the electronmicroscope (Table I). Thus we confirm the observation of Hommes and associates 5 that there is a deficiency of pyruvate carboxylase in Leigh's encephalomyelopathy, but we do not share the interpretation that the impaired gluconeogenesis would be the sole mechanism of this disease. We believe that an ineffectively operated Krebs trlcarboxylic acid cycle due to oxaloacetate deficiency may also play an important role in the pathogenesis. I n an attempt to supply the 4-carbon dicarboxylic acid continually and minimize the demand on gluconeogenesis, the formula was supplemented with L-glutamine, and the frequency of feeding was increased. Large doses of vitamin B~ were given to insure maximal rate of transamination. After two weeks' feeding with formulas containing 150 mg. of L-glutamine once every three hours, and vitamin Bs, 25 mg. four times a day, the infant became more alert and active, and less hypertonic, began to roll over from the prone to supine position, and had better head control. The mother was most impressed by her baby's improvement. The infant now appears to be thriving, and shows no sign of deterioration. Blood lactic acid has been lowered to 30 mg. per cent, blood pyruvic acid to 1.1 mg. per cent, and serum cholesterol elevated to 135 mg. per cent. Serum serine has been lowered from 52 #moles per cent to 12 #moles per cent, and serum asparagine elevated from none to 87 #moles per cent. The panorama of these biochemical changes seem to be appropriately explicable on the basis
1 90
Letters to the Editor
that uninterrupted sources of 4-carbon dicarboxylic acids for the Krebs cycle have been provided by frequent feedings, and by vitamin B6 through its versatile coenzymatic activities, including transamination and conversion of glutamate to a-ketoglutarate, and aspartate to oxaloacetate, and decarboxylation of glutamate to y-aminobutyrate and then succinate, a metabolic pathway specific to the central nervous system. With the intermediates thus replenished and the blockage of pyruvate carboxylation Obviated, the Krebs cycle is again able to utilize pyruvic acid, and subsequently to lower lactic acid, and serine levels in blood, and facilitate the synthesis of cholesterol. The remarkable increase of serum asparagine further demonstrates the improved efficiency and Krebs cycle in converting L-glutamine to L-asparagine via a-ketoglutarate, and oxaloacetate. In summary, we have found the deficiency of mitochondrial pyruvate carboxylase with pleoconia in liver tissue of our study very significant, and the favorable response of our patient to frequent feedings and vitamin Bs most interesting. Being aware of the brevity and paucity of our clinical experience with Leigh's encephalomyelopathy, we wish to share it by this letter in order to continue to remodel our thoughts on this disease. The urine assay for inhibitory factor was done by Dr. Jack R. Cooper, Yale University School of Medicine.
Thomas T. Tang, Ph.D., M.D. Thomas A. Good, M.D. Paul R. Dyken, M.D. Stanley D. ]ohnsen, M.D. Samuel R. McCreadie, M.D. Santiago T. Sy, M.D. Milwaukee Children's Hospital Milwaukee, Wis. 53233 Henry A. Lardy, Ph.D. Frederick B. Rudolph, Ph.D. Institute for Enzyme Research University of Wisconsin Madison, Wis. 53706 REFERENCES 1. Leigh, D.: Subaeute ne~rotlzing encephalomyelopathy in an ~ J. Neurol. Neurosurg. Psychiatr. 14: 216, 1951. 2. Montpetit, V. J. A., Andermann, F., Carpenter, S., Fawcett, .J.S., Zborowskasluis, 13., and Giberson, H. R.: Subaeute necrotizing encephaIomyeIopathy. A review and a study of two families, Brain 94: I, 1971. 3. Ebels, E. J., Blokzijl, and Troelstra, J. A.: A Wernicke-like encephalomyelopathy in chil-
The Journal o[ Pediatrics July 1972
4.
5.
6.
7.
8.
9.
i0.
dren (Leigh), an inborn error of metabolism ? Report of 5 cases with emphasis on its familial incidence, Helv. Pediatr. Acta 3: 310, 1965. Clayton, B. E., Dobbs, R. H., and Patrick, A. D.: Leigh's subacute necrotizing eneephalopathy: Clinical and biochemical study with special reference to therapy with lipoate, Arch. Dis. Child. 42: 467, 1966. Hommes, F. A., Polman, H. A., and Reenink, J. D.: Leigh's encephalomyelopathy: An inborn error of gluconeogenesis, Arch. Dis. Child. 43: 423, 1968. Cooper, J. R., Itokawa, Y., and Pincus, J. H.: Thiamine triphosphate deficiency in subacute necrotizing encephalomyelopathy, Science 164: 72, 1969. Cooper, J. R., Pincus, J. H., Itokawa, Y., and Piros, K.: Experience with phosphoryl transferase inhibition in subacute necrotizing encephalomyelopathy, N. Engl. J. Med. 283: 793, 1970. Pincus, H. J., Cooper, J. R., Itokawa, Y., and Gumbinas, M.: Subacute neerotizing encephalomyelopathy, Arch. Neurol. 24: 511, 1971. Johnson, D., and Lardy, H. A.: In Colowlch, S. P., and Kaplan, N. O.: editors: Methods in enzymology, New York, 1967, Academic Press, Inc., p. 94. McClure, W. R., Lardy, H. A., and Kneifel, H. P.: Rat liver pyruvate carboxylase, preparation, properties, and cation specificity, J. Biol. Chem. 246: 3569, 1971.
Intravenous alimentation To the Editor: The article "Intravenous alimentation in pediatric patients," by Heird and associates 1 is a scholarly review of an important medical development. While the discussions are eminently educational, we believe the authors have overemphasized the dependence on central veins in contrast to the peripheral vein for parenteral nutrition in the small infant. Their terms "mandatory" and "imperative" for hyperosmolar solutions to be given by large veins has not been our experiences or that of others, s, 4 While use of the central vein is necessary in the large infant for administration of adequate calories, peripheral veins are quite satisfactory and less hazardous for parenteral nutrition of the infant under 2 Kg. The slower flow rates and reduced concentration of protein and glucose advisable for the more immature infant allow the use of smaller veins and still promote growth. Our current solutions contains approximately 65 calories per i00 mI. (2 per cent protein hydrolysate, 10 to 13 per cent glucose, 1.5 per cent ethyl alcohol) and can be given at flow rates in