1456
`
`THE NEW ENGLAND JOURNAL Of MEDICINE
`
`June24, 1976
`
`sion of isotonic amino acids, the basic principles of body fuel
`regulation need not be altered to explain these findings.
`Firstly, in postoperative patients infused only with saline,
`peak rates of urinary nitrogen loss (observed on the second
`to fourth days) coincide with fivefold to 10-fold increments
`in blood ketones. 9•10 Secondly, administration of glucose
`alone (100 g per day) reduces nitrogen losses by 30 to 60 per
`cent in the postoperative period, despite suppression of ke(cid:173)
`tosis and stimulation of insulin secretion. 9•10 Thirdly, a ni(cid:173)
`trogen-sparing effect of ketone infusions has been observed
`only after prolonged fasting , a condition in which basal ni(cid:173)
`trogen losses are well below those observed in the postoper(cid:173)
`ative state.11 Fourthly, as shown elsewhere in this issue of
`the Journal by Greenberg et al., addition of 5 per cent dex(cid:173)
`trose to isotonic amino acids fails to impair their nitrogen(cid:173)
`sparing action. Fifthly, these authors also find that accentu(cid:173)
`ation of fat utilization by addition of a hypocaloric lipid
`emulsion to the amino acid mixture fails to improve nitro(cid:173)
`gen balance beyond that observed with amino acids alone.
`Nitrogen balance was identical in patients given only ami(cid:173)
`no acids, amino acids plus lipid, or amino acids plus glu(cid:173)
`cose. Noteworthy is the fact that in all three groups, admin(cid:173)
`istration of isotonic amino acids resulted in protein sparing
`well in excess of that observed with glucose alone.
`An interesting question raised by the observations of
`Greenberg et al. is the precise metabolic signals responsible
`for improved nitrogen metabolism in patients receiving ami(cid:173)
`no acid infusions. Two factors that warrant consideration
`are hyperaminoacidemia and hyperinsulinemia. In subjects
`fed protein meals, postprandial hyperaminoacidemia in(cid:173)
`volves primarily the branched-chain amino acids, leucine,
`isoleucine and valine. 12 These amino acids are unique in
`their ability to escape hepatic uptake while dominating ni(cid:173)
`trogen repletion in muscle tissue. 12 They are also particu(cid:173)
`larly effective in their ability to stimulate protein synthesis
`in muscle. 13 Interestingly enough, the hyperaminoacidemia
`observed by Greenberg et al. in the patients infused with
`amino acids alone or amino acids plus lipid involved the
`branched-chain amino acids, suggesting that the mecha(cid:173)
`nism of muscle nitrogen repletion may be analogous to oral
`protein feeding. In contrast, plasma amino acid levels did
`not rise in the group given amino acids and glucose. How(cid:173)
`ever, plasma insulin concentration was highest in the latter
`group. Hyperinsulinemia induced by addition of glucose to
`protein meals has recently been demonstrated to blunt the
`hyperaminoacidemia caused by protein feeding while stim(cid:173)
`ulating muscle uptake of branched-chain amino acids. 14 The
`intracellu lar availability of these amino acids for protein
`synthesis is thereby increased. Thus, perhaps insulin alter(cid:173)
`nates with the branched-chain amino acids as the circulat(cid:173)
`ing signal enhancing nitrogen retention in muscle. In sub(cid:173)
`jects fed pure protein meals, 12 or infused with amino acids in
`the absence of glucose, hyperaminoacidemia (involving leu(cid:173)
`cine, isoleucine and valine) may have a major role in im(cid:173)
`proving nitrogen balance. On the other hand, in subjects
`given glucose or glucose plus amino acids, hyperinsulin(cid:173)
`emia may effect a reduction in nitrogen catabolism in the
`absence of hyperaminoacidemia.
`Regardless of the mechanism involved, it is now clear that
`improvement in nitrogen balance induced by amino acid in-
`
`fusions in the face of caloric deficiency requires neither ke(cid:173)
`tosis nor hypoinsulinemia. The theory attributing a cata(cid:173)
`bolic effect to insulin or glucose (or both) thus cannot be
`sustained. Abandoning this scheme should not, however,
`detract from the clinical importance of the demonstration
`that isotonic amino acid infusions result in protein sparing
`in the postoperative period and in other catabolic states.
`
`Yale University School or Medicine
`New Haven, CT 06510
`
`PH1LIP FELIC, M.D.
`
`R EFERENCES
`
`I. Huxley T ; Collected Essays, VIII, Biogenesis and Abiogenesis, as quot(cid:173)
`ed in Familiar Medical Quotations. Edited by MB Strauss. Boston, Lit(cid:173)
`tle. Brown and Company, 1968, p 232
`2. Dudrick SJ, Macfadyen BY Jr, Van Buren CT, et al: Parenteral hypera l(cid:173)
`imentation: metabolic problems and solutions. Ann Surg 176:259-
`264, 1972
`3. Felig P: Nutritional maintenance and diet therapy in acute and chronic
`disease. Textbook of Medicine. Edited by PB Beeson. W McDermon.
`Philadelphia, \VB Saunders Company. 1975, pp 1389- 1398
`4. Blackburn GL, Flatt JP, Clowes GHA, et al: Peripheral intravenous
`reeding with isotonic amino acid solutions. Am J Surg 125:447-454. 1973
`5. Blackburn GL, Flatt JP. Clowes GHA Jr, Cl al: Protein sparing therapy
`during periods of starvation with sepsis or trauma. Ann Surg 177:588-
`594, 1973
`6. Hoover HC Jr, Grant JP, Gorschboth C, et al: Nitrogen-sparing in·
`travenous fluids in postoperative patients. N Engl J Med 293:172-175,
`1975
`7. Flatt JP, Blackburn GL: The metabolic fuel regulatory system: implica(cid:173)
`tions for protein-sparing therapies during caloric deprivation and dis(cid:173)
`ease. Am J Clin Nutr 27:175-187, 1974
`8. Normosol Multiple Electrolyte Solutions (Brochure No. 97-0032-R2-
`30). North Chicago, Illinois, Abbott Laboratories, September, 1975, p 3
`9. Blackburn GL, Flatt JP, Heddie R, et al : The significance of muscle pro(cid:173)
`tein and fat mobilization following injury for the design of parenteral flu(cid:173)
`id. electrolyte and nutritional therapy, Presented at the Glasgow Injury
`Symposium, Glasgow, Scotland, September 1l·12, 1975
`10. Giddings AEB: The control of plasma glucose in the surgical patient. Br
`J Surg 61:787-792, 1974
`11 . Sherwin RS. Hendler RG, Felig P: Effect of ketone infusions on amino
`acid and nitrogen metabolism in man. J Clio Invest 55:1382-1390, 1975
`12. Wahren J, Felig P, Hagenfeldt L: Effect of protein ingestion on splanch(cid:173)
`nic and leg metabolism in normal men and in patients with diabetes mel(cid:173)
`litus. J Clin Invest 57:987-999, 1976
`13. Fulks RM, Li JB, Goldberg AL: Effects of insulin, glucose, and amino
`acids on protein turnover in rat diaphragm . J Biol Chem 250:290-298,
`1975
`14. Sherwin R, Rosenzweig J. Soman V, et al: Effect of insulin and diabetes
`on protein and branched chain amino acid utilization. Diabetes (in press)
`
`"PROPPER" USE OF DESFERRIOXAMINE
`
`ALTHOUGH clinical problems involving iron are usually as(cid:173)
`sociated with a deficiency of this essential element, an ap(cid:173)
`preciable number of patients suffer from iron overload. This
`accumulation of iron can result from increased absorption,
`as in primary hemochromatosis and thalassemia interme(cid:173)
`dia, or from multiple blood transfusions, as in .6-thalasse(cid:173)
`mia major and hypoplastic anemia. Excess iron is deposit(cid:173)
`ed in body stores as ferritin or hemosiderin and can eventu(cid:173)
`ally amount to several hundred grams. The pathophysiolo(cid:173)
`gy of iron deposition in tissues -
`e.g., the heart and liver -
`is believed to be due to free radicals generated by the iron.
`Damage caused by such radicals leads to fibrosis, necrosis
`and eventual organ failure.
`The lack of an effective excretion mechanism for iron in
`man forces the physician to intervene either through phle(cid:173)
`botomy or by the use of specific iron chelators. Phlebotomy
`
`
`1 of 2
`
`Taro Pharmaceuticals, Ltd.
`Exhibit 1029
`
`

`

`Vol. 294 No. 26
`
`EDITORIALS
`
`1457
`
`'
`
`is particularly effective in treating primary hemochromato(cid:173)
`sis since the removal of 1 unit of blood removes approxi(cid:173)
`mately 250 mg of iron. When phlebotomy is contraindicat(cid:173)
`ed, chelation therapy has been attempted. Unfortunately,
`the use of chelators has met with limited success. Several,
`such as ethylenediaminetetra-acetate (EDTA) and diethyl(cid:173)
`enetriaminepenta-acetate (DTPA), have been abandoned
`because of toxicity. One chelator that has attracted inter(cid:173)
`mittent interest since its introduction in 1960 is desferriox(cid:173)
`amine. 1 This chelator, which is isolated from Streptomyces pi(cid:173)
`losus, has a very high affinity for iron and is without serious
`toxicity in man. However, after an initial flurry of investiga(cid:173)
`tive activity, it was realized tha t intramuscular administra(cid:173)
`tion of desferrioxamine on a c hro nic basis failed to bring all
`patients into iron balance (or negative iron balance). The
`, drug was able to chelate only a very small fraction of the
`iron in total body stores. Moreover, the daily intramuscular
`injections of the drugs were not well accepted by the chil(cid:173)
`dren or their parents, and, thus, its use was greatl y cur(cid:173)
`tailed in the United States.
`A small clinical trial of prolonged desferrioxamine thera(cid:173)
`py was continued in E.ngland.2 After six years it was appar(cid:173)
`ent that the rate of accumulation of iron in the desferriox(cid:173)
`amine-treated group was less than that in the control group.
`This study prompted a re-evaluation of desferrioxamine in
`the United States. The paper in this issue of the Journal by
`Propper et al. attempts to define conditions to improve the
`response to desferrioxamine. These workers have found that
`the slow continual infusion of desferrioxamine substantially
`increases the amount of excreted iron in patients with ,8-tha(cid:173)
`lassemia major. Presumably, this increased excretion oc(cid:173)
`curs because the drug has access to a replete chelatable pool
`that is slowly filled from otherwise inaccessible body stores.
`This observation should stimulate further studies of the
`pharmacology and potential toxicity of continual desferri(cid:173)
`oxamine infusions a nd eventually lead to the development of
`new drug delivery systems and depot forms of this and
`other chelators. The next few years, one may hope, will
`see an improvement in the understanding and funding
`of chelator therapy that will parallel the recent advances
`made in understanding the molecular pathology of thalas(cid:173)
`sernia.
`
`Rockefeller U niversity
`New York, NY 10021
`
`ANTHONY CERAMI, PH.0.
`
`REFERENCES
`
`l. Bickel H, Gaumann E, Keller· Schierlein W, et al: Iron-containing growth
`foctors, the sideramines, and their antagonists, the iron-containing a nti·
`biotics. sideromyci n. Experientia 16: 129- 1 JJ, 1960
`2. Barry M, Flynn OM, Letsky EA. et al: Long-term chelation therapy in
`thalassemia major: effect on liver iron concentration, liver histology, and
`clinical p rogress. Br Med J 2:16-20. 1974
`
`VIRUS MARKERS IN MULTIPLE SCLEROSIS
`
`OVER the past 20 years, many diagnostic tests for multi(cid:173)
`ple sclerosis have been described. However, none of them
`have proved to be specific for the diagnosis, which still rests
`on varied neurologic symptoms and signs occurring in char(cid:173)
`acteristic remissions and exacerbations.
`
`In the present issue of the Journal, Levy a nd Auerbach de(cid:173)
`scribe a blood test based on the adherence of peripheral
`blood lymphocytes to measles virus-infected tissue cul(cid:173)
`ture cells. Purified populations of lymphocytes from pa(cid:173)
`tients with multiple sclerosis formed rosettes in vitro when
`mixed with measles-virus-infected epithelial cells. Simi(cid:173)
`lymphocytes from control populations
`larly prepared
`showed much less rosetting activity; in fact, there was
`no overlap of patient and control values, suggesting that
`the assay may be of diagnostic importance. The positiv(cid:173)
`ity of the test in patients with multiple sclerosis was not
`affected by the severity, duration or activity of the dis(cid:173)
`ease.
`However, several reservations must be kept in mind be(cid:173)
`fore the authors' conclusions are accepted too readily. A
`wider range of control patients, including those with viral
`diseases, subacute sclerosing panencephalitis and immuno(cid:173)
`logic disorders (e.g., systemic lupus erythematosus) should
`be tested. The specificity of the reaction for measles virus
`should be analyzed by use of target cells chronically infect(cid:173)
`ed with other viruses, and by an attempt to block the roset(cid:173)
`ting by measles-specific antiserum. An effort should also be
`made lo determine whether the measles-receptor-bearing
`cells are T lymphocytes, B lymphocytes or still other cells.
`Although Valdimarsson et al. 1 have found that only T lym(cid:173)
`phocytes have measles receptors, others have shown repli(cid:173)
`cation of measles virus in both human T and B lympho(cid:173)
`cytes, as well as in monocytes. 2· • In patients with multiple
`sclerosis the numbers of B lymphocytes in peripheral blood
`are slightly increased, whereas T-lymphocyte numbers are
`slight ly reduced, s and there are no data concerning mono(cid:173)
`cytes.
`Levy and Auerbach wisely avoid drawing any conclusions
`concerning the role of measles virus in the pathogenesis of
`multiple sclerosis. A wide variety of viruses have been sug(cid:173)
`gested as possible causes of the disease since Poskanzer et al.
`suggested that it may result from exposure to an infectious
`agent during childhood. 6 Evidence suggesting a viral role
`has come from epidemiologic, serologic and histologic stud(cid:173)
`ies and from rare reports of virus isolations from brain tis(cid:173)
`sue. 7-is The viruses receiving the greatest attention have
`been members of the paramyxovirus group, particularly
`measles and parainfluenza-1'· 11 and a recently described
`transmissible agent referred to as the multiple-sclerosis-as(cid:173)
`sociated agent. 12
`15
`•
`Over 20 different studies have demonstrated that patients
`with multiple sclerosis have slight but consistently elevated
`serum measles antibody titers as compared with controls.7·8
`A few studies have also indicated that there may be local
`production of measles antibody in the central nervous sys(cid:173)
`tem, as reflected by elevated levels in the cerebrospinal flu(cid:173)
`id. 8•9 However, Amason et al. have demonstrated that the
`small increases in measles antibody levels observed by some
`groups may be related to the unusual distribution of histo(cid:173)
`compatibility types in patients with multiple sclerosis. 16 Per(cid:173)
`sons with HLA-3 had increased measles antibody titers
`whether or not they had multiple sclerosis; since patients
`with the disease have a disproportionate prevalence of HLA-
`3, the elevated measles antibody titers may reflect histo(cid:173)
`compatibility type rather than presence of multiple sclero-
`
`
`2 of 2
`
`Taro Pharmaceuticals, Ltd.
`Exhibit 1029
`
`