Snyderman Et Al 1964 the Essential Amino Acid Requirements of Infants_isoleucine

8/12/2019 Snyderman Et Al 1964 the Essential Amino Acid Requirements of Infants_isoleucine

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31 3

T H E A M E R IC A N JO U R N A L O F C lin ica l N u tr it ionD E C E M B E R 196 4 V O L U M E 1 5, N U M B E R 6

O rig in a l C omm un ica tion sThe E ssen tia l Am ino A cid R equ irem en ts

o f In fan tsIX I soleucine

S E L M A E . S N Y D E R M A N , M .D .,* A U D R E Y B O Y E R ,t P A T R IC IA M . NORTONE L L E N R O IT M A N t A N D L . EMMETT HOLT J R. M.D.

T iiis stud y of th e iso leu cin e requ irem en t o fth e no rm al in fan t is pa rt o f a se rie s to de -

te rm ine the es sen tia l am ino ac id requ irem en tso f no rm a l in fan ts . A s in p rev iou s stud ie s aco m ple te ly sy n the tic d iet w as used , the n itro -g en m o iety o f w hich w as a m ix tu re o f eig h teenL -am ino acid s in the p ro portion in w h ichthey a re fou nd in h um an m ilk . A fte r a co n-tro l pe rio d on an ison itrogen ous m ilk fo rm ulafo llow ed by on e on th e syn th etic d ie t w ith th efu ll co m plem en t o f iso leuc ine , th e iso leuc inew as co m ple te ly w ithd raw n . I t w as th en re -in trod uced in step w ise fash ion to de te rm in ethe m in im al am oun t w h ich w ou ld m a in ta inw e ig h t g ain an d n itrogen reten tio n a t the co n-tro l leve ls . T he n itrogen in take w as k ep t con -

F ro m the D epa rtm ent of P ed iatrics , N ew Y ork U n i-versity S cho ol of Medicine N ew York New York.

Reci pient of Career Scientist Award of the Hea lthResearch Council of t he City of New Y ork under Con-tract 1 -161 . A ssocia te P rofe sso r o f P e d ia tric s; t C h e m -is t; A ss istan t in P ed iatrics; R e cip ien t of C areerS cien tis t A w ard of th e H e alth R ese arc h C o un cil o f theC ity o f N ew Y o rk und er C ontract 1 -15 2 . P rofessor o fPed iatr ics.

T h is stu dy w as supp orted in p art by gra n ts fro m theU . S . P u blic H ea lth S erv ic e (A M 0 105 5) an d theN a tion al D airy C ou ncil.

stan t by the sub stitu tion o f g lyc ine fo r th eiso leu cin e tha t w as rem oved . A ll feed ing pro -cedures , m e tabo lic tech n ic s and labora to ryde te rm in a tions w ere ca rr ied ou t a s p rev ious lydescr ibed s w ith th e excep tion of the p lasm aam ino ac id de term in atio ns. T he m e thod o fP iez an d M o r r i s9 w as sub stitu ted fo r tha t o fS packm an , S te in and M oo re {17 6} during th ela tter pa rt o f th is study . C ho les tero l w as de -te rm in ed by a m o dif ica tion of the m e tho d ofB loor e t al)

T he sub jec ts w ere six norm a l m a le in fan tsw ho h ad rem a ined in the ho sp ita l b ecause o fsoc ia l rea son s. T w o had b een b orn p re -m a tu re ly an d had h ad an un ev en tfu l co urse inthe p rem atu re un it fro m w h ich th ey w ere d is-cha rg ed so m e tim e be fo re the stu dy w as in -i t iated .

O B S E R V A T IO N S O N T H E IS O L E U C IN E R E Q U IR E M E N TT he iso leuc ine req u irem en ts in d iffe ren t sub -

jects va ried from 95 to 126 m g. pe r k g . pe r c lay .In d iv id ua l p ro toco ls fo llow .Baby A . U . F ig . 1 , Tab le I . T his pre m a ture in fa n tw eighe d 2 .21 kg . at bi rth and 2.75 kg . a t o ne m on thwhen he was adm itted to the stu dy . A fter co n tro l


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20 29 0 20 30 9 9 2v 9 9 29 5 25F e b r u a r y Ma r c h Ap r i l Ma y J u n e

S ny derm an et al.

Continued on faci ng page

31 4B a b y

P l a s m aC h o l e s t e r o l 2

(m g /IO O m l. )T o ta l P ro te in

A l b u m i n .G to b u li n

gr.i./lO O m l.)

Nf l t r ogenR e te n tio n S

mg . / k g . / d o y I

W e i g h t (k g .)

I s o l euc ineI n take 92

(m g . /k g ./d a y ) ,o o M

F I G. 1. B aby A U . A n isoleucine intake o f 7 9 m g pe r kg. per day w as ade-quate fo r this infant. The dotte d line re pre sents the 3rd percentile w eig htc u r v e .

T A B L E I

M etabolic D ata

I)ate.Isoleucine

Intakem k /d )., g . y

Ave r ageW e igh t

k ).

N itr oge n g m /d ay)

Ur in ar y . .Cr e at in in em g . /k g . /

d ay)

P lasm a P roteingm ./100 m l . ) Ch o le s -

t e r o l m g . /100

m l . )n tak e U r ina ry F ec a l

Re t e n -t ion

m g. /kg. /

d ay)T ota l A lb u -mm

G loh u -un

Baby AU

3/22-3,253/1-3/43/7-3/103/14-3/173/21-3/243/28-3/314/4-4/74/11-4/144/18-4/214/25-4285/2-3/55/9-5/125/16 5/195/23-5/265 /30 - 6 /266-6/96/13-6/16620-6 3627-630

192 E.M.)25 0012 3808010 010 012 112 116 016 023 623 618 8 EM.)188 EM.)797979

2.893.103.103.153.353.453.603.703.843 . 954.054. 24 . 334 . 474.684.855.025.235.40

1.471.601.601.601.661.731.771.871.912. 02.022.062.122.192.262.372.422.522.66

0.550.811.010.810.800.980.870.991.081.21.161.271.271 . 111.081.161.181.271.41

0 . 3 00.130.310.200.200.120.160.160.150.190.150.120.150 . 150.320.290.150.140.13

21 521 390

18 819 718 120 519 517 715 517 416 116 320 818 318 921 821 420 8

11.812 511.212.19. 9

11.110.610.811.411.610.110.910.0

9.5......-........

6.01. . .. .

5.90. . ....

5.32...

6.52...

6. 66. 0

...

...

...

...6 . 175.69

...

3.93. . .. . .

3.62. . ....... { 149} . .

4.33......

4.02............

4. 313.53

.

2.08. . .. . .

2.28. . ..........

2.19......

1.98............

1 . 862.16

...

18 519 518 322 420 014 613 313 618 812 61:92.115......

14815 412613 1132


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4 T h r ee d a y p e r iod .t Tw o d a y p e r iod .

Iso leuc ine R equirem ents of Infants 315

T ABL E I continuedM etabo lic D ata

Da t e.I s o l euc s ne

I n t a k e(m g / k g / d a y )

A v e r a g e.We i g h t

(kg . )

N it r o gen (gm /d a y )-

U r i n a r y. .C r e a t i n i n e

(mg/kg .d a y )

P la sm a P r o te in(gm ./100 m l.)

Cho le s -t e r o l

(mg . /100m l . )n t a k e U r in a r y F o c a l

R e t e n -.t i on(mg . /kg /d a y )

T o t a l A l b u -mmG l o b u -

lb

Baby C P

5 / 4 - 5 / 75/11-5/145/18-5/215/25-5/286/1-6/46/8-6/116 / 1 5 - 6 / 1 86 / 2 2 - 6 / 2 56 / 2 9 - 7 / 27 / 6 - 7 / 9

1 8 4 EM )24 0012 012 112 18 31 0 31 0 32 4 0

2 . 8 72.983. 03.073.203.353 . 4 53 . 5 63 . 7 13 . 8 3

1 . 4 91.501.551.551.611.721 . 7 71 . 8 21 . 8 71 . 9 2

0 . 5 30.691.660.830.770.680 . 8 51 . 0 10 . 8 91 . 0 8

0 . 2 40.120.070.090.070.130 . 1 00 . 1 20 . 0 80 . 0 8

2 5 123 2

-6 020 824 027 02 3 81 9 42 4 01 9 9

1 3 . 611.412.612.112.29. 4

1 0 . 49 . 0

1 2 . 61 2 . 8

. . .

. . .5.545.80. . .

5.00. . .

5 . 5 45 . 0 6

. . .

. . -. . .

2.943.73

. . .3.00. . .

3 . 2 82 . 7 4. . .

. - - /... . . 13 9

2.60 9 32.07 128. . . . . /

2.00 1 5 3- . . . . .

2 . 2 6 1 3 22 . 3 2 1 4 0

. . / -. .

Baby ES

3 / 1 9 - 3 / 2 23/26-3/294/3-4/64 / 1 0 - 4 / 1 34 / 1 7 - 4 / 2 04,24-4/275/1-3/45 i 8 - 5 / l l

1 8 6 EM )24 007 87 810 310 32 3 9

3 . 0 83.263.313 . 4 03 . 5 23.643.783 . 9 8

1 . 5 8 0 . 7 01.58 0.911.55 1.381 . 5 8 0 . 7 11 . 7 1 1 . 1 91.77 0.881.86 0.951 . 9 0 0 . 9 3

0 . 2 40.080.140 . 1 60 . 1 30.100.140 . 1 5

2 0 718 1

92 0 91 1 121 620 42 0 6

. . .. . .. . .. . .. . .. . .. . .. . .

. / .. . -. . .

4.56. . /

5.675.67. . -

. . - . . .

. . . . . .

. . . . . .2.70 1.86

. . - . . .3.70 , 1 . 9 73.65 2.02. . . . . .

17 211 01 0 711 210 81 0 610 411 2

Baby FE

1 0 / 5 - 1 0 / 81 0 / 1 2 - 1 0 / 1 510/19-10/221 0 / 2 6 - 1 0 / 2 911/2-11/511/9-11/1211/15-11/1811/21-11/2411/28-12/11 2 / 5 - 1 2 / 8

1 8 8 EM )2 3 001 2 079.579.59911 911 92 3 7

3 . 3 33 . 5 43.583 . 8 03.974.084.204.354.604 . 7 0

1 . 5 51 . 7 11.611 . 8 71.921.982.052.162.242 . 3 0

0 . 6 80 . 8 61.390 . 9 61.221.331.161.221.201 . 1 8

0 . 2 10 . 1 50.110 . 0 90.100.120.220.150.070 . 1 0

1 9 81 9 731

2 1 615 112 515 918 021 12 1 7

1 1 . V1 3 . 010.01 1 . 912.012.714.012.011.41 1 . 5

. . .6 . 2 56.246 . 2 65.845.475.24

. . .6.215 . 6 8

. . .4 . 2 04.123 . 3 73.593.432.90

. . .3.533 . 3 7

. . .2 . 0 32.122 . 6 82.252.042.34

. . .2.682 . 3 1

...1 6 2918 9

10 311 614 31 2 814 71 2 5

Baby P O

3/9-3/123/16-3/193/24_3/26*3 / 3 0 - 4 / 24/6-4/94/13-4/164/20-4/234/27-5/305/4-5/75/11-5/14

184 EM.)24 001 2 612 812 618 318 024 024 0

2.983.153.113 . 2 03.273.373.523.703.783.90

1.521.561.441 . 4 81.621.721.831.831.881.92

0.540.560.810 . 5 80.600.850.830.891.061.05

0.380.120.140 . 1 50.110.130.220.110.120.08

20 127 615 52 3 427 824 822 222 418 620 0

13.49. 59. 89 . 8

10.415.815.313.612.011.6

. . .4.645.08. . .. . .. . .

5.76. . .. . .. . .

. . /2.482.90. . .. . .. . .

3.94. . .. . .. . .

. - .2.152.18

. . .

. . ./ . .

1.80. . ./ . .. / .

-..14 414 2-... . /...15 9......1 5 2

Baby T

1/26-1/292 / 2 - 2 / 52/9-2/122 / 1 6 - 2 / 1 92/22-2/23t3/2-3/53/9-3/123 / 1 6 - 3 / 1 93/23-3/263 / 3 0 - 4 / 24 / 6 - 4 / 9

200 EM.) 3.052 4 2 3 . 2 2248 3.350 3 . 3 80 3.4181 3.52118 3.761 1 8 3 . 9 599 4.161 0 0 4.242 4 1 4 . 4 3

1.521 . 6 11.721 . 7 21.721.771.831 . 9 22.042.152 . 1 9

0.380 . 5 30.541 . 1 71.441.090.770 . 8 80.881.081 . 0 9

0.260 . 1 30.160 . 1 80.090.160.120 . 1 20.200.180 . 1 7

28 82 9 530 41 0 855

14 725 02 3 323 021 02 . 0 9

14.01 0 . 58. 4

1 0 . 913.612.511.11 0 . 311.211.3

9 . 5

5.325 . 4 4. . .. . .

4.775.29

. . .

. . .5.525.99. - .

3.083 . 0 3. . .. . .

2.752.57. . /. . /

3.314.25

/ . .

2.242 . 4 1- / .. . .

2.022.72. / .. / .

2.211.75

. . .

13 51 2 212 3-..79.5

11 6. -....

10 210 8

...


4/9

5

2 83

B a b y C . P .P l a s m a 20 0

C ho l e s t e r o l(m g / I OO ml. )

T o t a l Pr o t e i n LAlbumin # { 1 4 9 }

G lo b u lin( g m . l O O ml. ) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

N i tr o g e nRe t en t i on

(m g . /kg ./d a y )

. 3 0 0 ] 2 4 0I s o l e u c i n e 2 0 0 j 12 0 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _(m g. /k g. /d ay )0 0 o

0 iO 3 0 0M a y J u n e J u ly

FIG. 2. B aby C .P. T he isole ucine req uirem ent o f th isin f ant lay b etw eeii K 3 and 103 iig . p er k g. pe r d ay .

l eriod s d uring w hich he w as m aintaine d o n an iso-nitrog eno us ev al o rate d m ilk f o rm ula and on a sy n -the tic die t c ontain ing all the am ino acid s, o n w hic hhe g ain ed w e igh t and retain ed ad eq uate am ou nts ofn itrog en, iso leuc ine w as elim in ated f rom the diet .T h i s resu lted in som e loss in w eig ht and a m ark eddec rease in th e am o unt of n itrog en retain ed. W h enpro v id ed w ith an intak e o f 8 0 m g. pe r k g . pe r day o fiso leu cin e h is rate of w eight gain and th e am oun ts ofn itrog en retain ed w ere adeq uate. S u bse qu ent in -cre ase s in th e in tak e o f iso leuc ine to 10 0, 12 1, 16 0and 23 0 m g. pe r k g . per d ay and o n an ison itro ge nou sev apo rated m ilk f orm ula did n ot acc ele rate therate of w eight gain nor inc rease the am ou nt of n itro-ge n re ten tion . A se con d trial on 7 9 m g . pe r k g. pe rday again d em ons trated th e ade quacy o f th is in tak ef or th is in f an t. S in ce a low er in tak e o f iso leu cin ew as no t trie d , i t is no t p oss ib le to say w h eth er orno t the isoleuc ine req uirem ent in th is bab y w as ev enlow er. H is w e igh t curv e rem ain ed b elo w b ut paral-le l t o t h e 3 r d p e r c e n t i l e cu rv e ex cep t d uring th ep eriod of iso leuc ine d ep riv atio n .Baby C.P . F ig . 2 , Table I . T his bab y w as b ornp rem ature ly ; his birth w e igh t w as 1.93 k g. H e w as

Ia ? a l tAlb {149}0 l a b , , l

l g . / l O 5

FIG. 3. B ab y E .S . T h e iso leu cin e requ ire m e nt o f th isin f ant lay betw ee n 78 an d 103 m g . per k g . p er d ay .

316 S ny derm an e t al.

three w eek s o ld an d had attained a w eig h t o f 2 .8 k g .at th e tim e of study . T h e rate o f w e igh t g ain an dth e am o unts of n itroge n retain ed w e re ade quatedu ring tw o co ntrol p erio ds w he n he w as giv en anev apo rated m ilk f o rm u la an d a sy nthetic d iet co n-tam in g all th e am in o ac ids . W h en isoleuc inc w aselim in ate d f rom th e d iet, there w as no gain in w eightan d the n itro gen balan ce bec am e ne gativ e. T head m in istration o f 12 0 m g. of iso leuc ine pe r k g. pe rday resulte d in a goo d w e igh t gain and ade quatenitro gen re ten tion d uring a th ree w ee k s trial w ithth is am ou nt. T he rate of w eight g ain , but n ot th eam ou nts of n itro gen re tain ed, dec reased im m e diatelyw hen the isole ucine in tak e w as re du ced to 8 3 m g .pe r k g. pe r d ay . O n an in tak e o f 10 3 m g . p er k g . pe rday , the w e igh t g ain an d nitro gen reten tio n w e reeq ual to that w hic h o ccu rred in a subseq uen t p eriodd uring w h ich th e in f an t w as m ain tained on a die tco ntain in g a f u ll co m p lem en t o f the am in o acid s.T h us it appe ars th at the isole ucine re qu irem en t inth is b aby lies be tw een 83 and 1 03 m g . pe r k g. pe rd ay . B e cau se of his low birth w e igh t, the usual

24 gro w th curv es canno t be e m p loy ed to asse ss the ad e-io3 c luacy o f his w eight gain .

Baby ES. F ig . 3 , Table I . T h i s w as a f u l l t e r mb ab y w h ose b irth w eigh t w as 2.7 k g . H e w as threew ee k s old an d w e igh ed 2.9 5 k g. at the tim e of study .T he rate of w e igh t gain and th e am o un ts of n itro genre tained w ere ade quate in th e co ntro l period s during

B y ES .

:)

30 02 0 0 8 6 .2 4 0 3 9

( /k g /d )1 0 {1 7 6 } A A o 7 8 0 38 2 7 6 1 6 2 6 6 6

M ., *p l M .y


5/9

w hich he w as m aintained on an evaporated m ilkform ula and a diet containing all the am ino acids.The elim ination of isoleucine from the diet resultedin a sm all w eight loss and a sharp reduction in theam ount of nitrogen retained. O n an intake of 78m g. per kg. per day, the infant continued to gainw eight but the am ounts of nitrogen retained de-creased during the second w eek on this regim en.W eight gain and nitrogen retention on an intake of103 m g. per kg. per day w ere eciuivalent to thatw hich ensued in the succeeding control period dur-ing w hich the baby w as given a full com plem ent ofisoleucine. Therefore, it is apparent that the iso-leucine requirem ent in this child lies betw een 78and 103 m g. per kg. per day. T he w eight curveparalleled the 3rd percentile curve except duringthe period of isoleucine w ithdraw al.

Ba by F E . F ig . 4 , Ta b le I . T his baby w eighed 3.35kg. at birth. H e w as tw o w eeks old and w eighed3.05 kg. w hen he w as adm itted to the study. D ur-ing control periods w hen he w as fed evaporatedm ilk and a diet containing all the am ino acids, hisrate of w eight gain and the am ounts of nitrogen re-tained w ere good. W hen isoleucine w as w ithdraw n

B a b y F E .

P l a s m a 20 0

( m g/ l OOm ) o0

T o ta l P ro te in AA lb um in {1 4 9 }

Gl o bul i n t o(g m /IS O m l. )

N i tr o g e nR e te nt i o n

(mg . / k g / d a y )

B a b y P .O . : { 1 4 9 }P l a s m o 2 0 0

C h o le s te ro lg . .

T o t a l Pr o t e i n A

G lo b u lin : i : T i i T i(g m / l OOm l . ) -

tter: ::(m g / kg / da y ) , 0 0

I

:: -3025l s o l e uc i ne 3 0 0 1 2 4 0

Intake 2 0 0 - . 1 8( mg . / k g . / d ay I 00 N I 07 16 26 5 5 2 5 5 5

Ma rc h A pril Ma y

FiG . 5. B aby P.O . This infants isoleucine require-m ent is less than 126 m g. per kg. per day. T he dottedline represents the 3rd percentile w eight curve.

there w as no gain in w eight and a m arked decreasein the am ount of nitrogen retained. O n a trial w ith120 m g. of isoleucine per kg. per day, w eight gainand nitrogen retention w ere adequate. 1-Tow ever,on intakes of both 79.5 and 9 9 m g. per kg. p e r d a yw eight gain and nitrogen retention w ere 1)0th sub-norm al. A second trial on an intake of 119 m g. perkg. per day again resulted in adequate w eight gainand nitrogen retention sim ilar to that w hich oc-curred w hen he w as given the full com plem ent of iso-leucine. It w as concluded that the isoleucine re-quirem ent in this baby lay betw een 99 and 119 m g.per kg. per day. This childs w eight rem ained be-tw een the 3rd and 10th percentile curves throughoutthe study period.

Ba by P .O . F ig . 5 , Ta b le I . T his baby w eighed2.27 kg. at birth. H e w as three w eeks old andw eighed 2.77 kg. w hen he w as included in the study.A fter control periods during w hich he w as m aintainedon an evaporated m ilk form ula and the am ino aciddiet w ith a full quota of isoleucine, the isoleucinew as elim inated from the diet. T his resulted in som ew eight loss and a decrease in nitrogen retention.

g I t k /d y b N m b e D r n b

F I G. 4. B aby P.E. The isoleucine requirem ent of thisinfant lay betw een 99 and 119 m g. per kg. per day.The dotted lines represent the 3rd and 10th percentileweight curves.

Isoleucine R equirem ents of Infants 317


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Baby TA .

(m g /100 m l.) :1 Total P ,o,eir i

Albumin {149}G lob.li,,O

(gm .IO O m l.)

Nit o ge

(m g.,kg./doy)

W eight(kg .

* L ow er intakes not tried.

318 S n y d e r ma n e t a l .

l s o l e 2 c i o e 20 0 1 20 0 Io t a k e { 1 7 6 } { 1 7 6 } 8 { 1 7 6 } { 1 7 6 }

(mg /kg/day) 0 {149} 2 6 2 5

January February M arch A pril

FIG . 6. B aby TA . This infant s i soleuci ne requi rementl ay betw een 1 and 99 nig. per k g. per day . The dottedl ine represet i ts the 3rd percenti le w eight curve.

Afte r bei ng on this regimen for one w eek, some red-ness of the buccal mucosa w as noted; i t w as mostmarked at the juncti on w i th the verm i l ion l )order .Fissures were al so ev ident at the corners of themouth. I n addi ti on, some tremors of the arms andl egs w ere noted. T hese symptoms began to subsideimmediately af ter isol eucine supplementati on; themucosal l esions w ere much improved af ter 24 hours.A n in take of 126 rng. of i soleucine per kg. per dayresul ted i n w eight gain and ni trogen retenti on sim i -lar to that w hich occurred w hen he recei ved 180and 240 mg. per k g. per day . These f i ndi ngs indi -cate that the requi rement i n thi s chi l d w as less than126 mg. per kg. per day . Since a trial on a l ow erintake w as not carried out, w e do not know howmuch under this amount his m inimal requi rementmay have l e e n . T h i s baby s w ei ght curv e w as belowthe 3rd percenti le and remained paral l el to i tthroughout the studs per iod.Baby TA. F ig . 6 , Table I . This baby weighed2.58 kg. at bi rth. H e was three w eek s old and hadattained a weight of 2.72 kg. w hen he w as i ncl udedi n the study . D uring control peri ods on an evapo-rated m i lk formula and on the ful l am ino aci d di et

he retai ned unusual l y l arge amounts of n itro gen.Presumabl y , thi s w as due to hi s l ow bi rth w eightand young age. W hen isoleuci ne w as w i thdraw ncompletely f rom the di et, he immediately stoppedgaini ng weight, and there was a sharp decrease inthe amount of ni trogen retai ned. A f ter a w eek onthi s regimen, the chi l d became lethargic and hi sappeti te w as poor . A t the same time the buccalmucosa became i njected and f issures appeared at theangl es of the l ips. On the tenth day, tw o episodesof tw i tching of the arms and l egs w i th upwardmovement of the eyes occurred af ter stimulation ofthe chi ld. H e was given isoleucine immedi ately andtw i tching di d not recur. I n a matter of hours heseemed less l ethargi c. \V i th in tw o day s, the lesi onsnoted in the mouth and l i ps began to subside. Onan intake of 81 mg. of i soleucine per kg. per daynei ther w eight gai n nor ni trogen retent ion w as ade-quate. A n intake of 1 18 mg. per kg. per day resul tedi n normal w eight gain and ni trogen retention. Onan intake of 100 mg. per kg. per day the rate ofw eight gain and the amount of ni trogen retained wasof the same order of magni tude as that on a controlintake of 241 mg. per k g. per day . l i ence the iso-l eucine requi rement i n thi s chi l d i s betw een 81 and 100mg. per kg. per day . H is w eight curve paral l el edthe 3rd percenti l e curve w henever hi s i sol eucine in -take w as adequate.

A summary of the requi rement data on thei ndi v idual subjects is giv en i n Table I I .

M E T O LIC O SE R V T IO NS

A l l metabol i c data are recorded in T able iand depi cted graphi cal l y i n Figures 1 through 6.D uri ng peri ods of i nadequate i sol eucine intak eni trogen retenti on w as poor as a resul t ofgreater urinary ni trogen loss. T he amount of

T L E II

S u mma r y o f Observat ions on the Isoleucine Requi rement

BabyIsoleuci ne Intakemg/kg/day)

Inadequate A dequate

TA . 81 99P.O. ... 1 2 6ES. 7S 103C.P. 83 103A U . ... 79*P.E. 99 119


7/9

9.64

N o , m a l {149}--. {149 }

2.5

2.0

.5 -

0.5

I 1111

. 0 -

I I I I I I I I

F I G . 7. The plasm a am ino gram in iso leuc ine w ith-draw al. Tile shade d are a represents 1 s tandard dev ia-tio n abo ve am id belo w the av erag e for infants of thesam e age giv en the am ino acid die t w ith the full com -ple me nt of iso leuc ine .

C on t r ol s* m g./100 m l .) V alu es in Su b j ects on I soleucin e-F r ee D iet s m g./100 m l .)

E S. P.E . P .O . T A . A ver ageta n d a r dDeviation

0 . 3 1 0 . 2 6 0 . 0 40 0 30 3 7 0 . 1 8 0 . 1 2 0 . 4 2 0 . 4 7 0 . 0 6 0 . 3 8 0 . 2 8 0 . 4 4 0 . 4 5 0 . 2 1 0.640.610.44

Ra n g e AU. C. P .

1 .81 -3 /92 2 .9 4 3 .540 . 2 9 - 1 . 1 4 . . . .t r a c e - 0 . 1 5 0 . 1 2 0 . 2 40 . 0 8 - 0 . 1 9 0 . 4 8 t r a c e1 .08 -2 .34 2 .83 2 .900 . 4 9 - 1 . 1 6 ...0 . 3 1 - 0 . 9 0 0 1 7 0 . 1 80 . 8 5 - 2 . 4 6 1 . 5 2 1 . 2 90 . 9 4 - 2 . 1 8 ...0 .13 -0 .29 0 .23 0 .390 . 4 1 - 1 . 8 7 .. . ..0 . 5 4 - 1 . 6 4 1 . 66 3 . 7 41 . 1 5 - 2 . 2 3 2 . 3 4 . 1.371 . 1 1 - 1 . 8 8 2 . 0 8 1 . 7 50 . 2 2 - 0 . 8 1 0 . 4 9 . 0 . 571 . 6 9 - 3 . 1 5 2 . 7 5 2 . 2 90 . 8 2 - 3 . 0 1 . 9 2 : 3 . 3 31 . 1 3 - 2 . 7 9 2 . 6 3 3 . 5 8

Ave r a g eChange

7; )

- 1 1 3

+ 67

+ 1 - I S

+1 5+7 5

+ 475+ 6 0

* Sin ce cont r ol p lasm as of t hese in fan ts w er e not avai l ab le, p lasm as of f i f t een in f an ts of th e sam e age fed on th e sam e am in o acid d ietw i th a f u l l com p lem ent of i soleu cin e ar e b ein g u sed as cont r ol s.

t a-am in o n -b u ty r i c acid . T h e h igh plasm a glycin e can b e at t r i b ut ed to th e ex t r a gl ycin e ad ded in place of th e i soleu cin e t o k eel ) th e d iet i son i t r ogen u s. I soleucin e an d leu cin e.

Iso leuc ine R equirem ents o f Infants

nitrogen lo st in the feces rem ained re lativ elycons tant regardles s o f the dietary intake.

A n i n t e r e s t i n g o b s e r v a t i o n wa s t h e d e c r e a s ein plasm a cho les tero l w hich occurred in cer-tain infants during periods of iso leuc ine w ith-draw al. Of five infants w ho se bloo d cholestero lleve l w as studied, three had a prom pt dro p to1 0 0 mg . p e r cent o r le ss . H o w ev er, w henadequate intakes of iso leuc ine w ere resto red,these re turned to contro l leve ls . In one otherbaby A . U .) there w as a g radual decrease inplasm a cho les tero l w hich persis ted w hile he w asmaintaine d on low or m arg inal intakes o fisoleucine.

Co m ple te quantitativ e analy se s o f the freeam ino acids of the plasm a w ere m ade in six in-f a n t s after they had been o n the iso leuc ine -freereg im en fo r o ne w eek. In each c ase the iso-leuc ine lev el o f the plasm a fe ll sharply . Inaddition, there w as an e levation in the leve lo f certain other am ino acids. The tyrosinelev e ls w ere o f spec ial intere s t; they w ere inthe no rm al rang e in three plasm as , slig htlyincreased in o ne C.P.), and g reatly e lev atedin the o ther tw o P.O. and TA .) . One v alueo f 2 9 .3 m g . per 1 0 0 m l. is 2 3 t imes the no rm al

T A B L E I I I

Plasm a A m ino A cids

31 9

A m in o A cidAve r a g e

A lanin e 2.62A r gin ine 0.78A spar t i c A cid 0. 10B ut y r i n et 0. 1 4G lycin e 1.61H ist i d i n e 0. 8 3I soleu cin e 0.56L eucin e 1 15L ys ne 1.71Me t h i o n i n e 0 . 2 4O r n i th in e 0.95Phenyla lan ine 0 . 9 5Pr ol in e 1.68S e r i n e 1 . 4 4T a u r i n e 0 . 4 2T h r e o n i n e 2 . 4 1T y r o s i n e 1 . 5 1Va l i n e 1 . 9 1

28 4 144 27 280 . 8 0 . 9

0.15 t r a c e 0 . 1 0 . 30 . 1 6 t r a c e 0 . 2 0 . 22 . 4 7 2 . 0 4 2 . 0 3 . 01 . 0 8 0 . 8 6 1 . 2 0 . 8

0 . 1 3 0.26 0 . 3 3 . 21 . 3 1 0 . 7 0 1 . 9 . .2 . 4 3 2.56 3 . 6 2.80 . 2 8 0 . 1 3 2 0 . 2

0 .99 1 0 1 . 11 . 4 4 0 . 7 3 2 / 9 4 . 32 .52 1 .3 9 1 .9 2 .22 . 3 5 1 .5 8 2 .6 :3 .90 .27 0 .39 1 .6 1 .12 .93 1 .6 2 3 .3 3 . 22 . 3 2 0 .85 29 :s 1 3 . 62 .48 1 .3 6 1 .4 6 .7

2 . 6 80 . 8 30 . 1 50 . 1 82 . 5 30 . 9 30 2 11.352 . 860 . 2 41 . 02 . 3 61.882 . 380 . 7 42 . 718 . 643 . 0 3


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32() Snyderm an et al.

control value. Phenylalanine levels w ere alsoelevated in the infants w ho had the hightyrosine levels. Plasm a serine, valine andlysine also tended to be high. These data areincluded in Table III and are show n graphically I i Figure 7.

C O M M E N TS

Infants fed com m only used evaporated m ilkform ulas receive approxim ately 250 lug. ofisoleucine per kg. of body w eight. This istw ice as m uch as the highest requirem ent foundin our study. The m argin of safety is not sogreat w hen infants are fed hum an m ilk ; suchinfants receive approxim ately 130 m g. perkg. per day.

O ur experience w ith infants m aintained onlow protein diets suggests the isoleucine re-quireiiient of infants on a natural diet is nohigher than that of infants on a com pletelysynthetic diet. W hen given supplem ents ofsonie form of unessential nitrogen, the rate ofgrow th and the am ounts of nitrogen retainedhave been adequate in infants on diets con-tam ing as little as 1.1 to 1.3 gm . per kg. ofc o w s mi l k p r o t e i n Y Us i n g t h e f i g u r e s a v a i lable for the isoleucine content of cow s m ilk, w ecalculated that these infants w ere receiving71 to 4 m g. p e r k g . p e r d a y of isoleucine.

The elim ination of isoleucine from the dietresulted in m ore severe m etabolic aberrationsthan have been noted w ith the w ithdraw al ofother essential a mi no a c i ds i nc l ud i ng a n a ctual w eight loss in tw o subjects and a m uchgreater decrease in nitrogen retention thanh a s b e e n o b s e r v e d i n o t h e r s t u d i e s . I n o u rstudies w ith infants the occurrence of negativenitrogen balance has been very rare as theresult of an intercurrent infection superim -posed on the om ission of an essential am inoacid. The severity of the m etabolic changesa n d o f t h e s y mp t o ms i n i n f a n t s ma i n t a i n e do n a n isoleucine-deficient diet are in keepingw ith the observations of R ose et al.34 andof Sw endseid and D unn5 in adults. The oc-c u r r e n c e o f sym ptom s involving the centralnervous system in tw o subjects is unique inour experience, although w e have observedredness of the buccal m ucosa and fissures atthe corners of the lips follow ing the com plete

w ithdraw al of phenylalanine from the 2and an eczem atoid rash follow ing the om issionof histidine from the diet of young infants.8

W e can find no adequate explanation forthe fall in plasm a cholesterol levels w hichw e also observed after the w ithdraw al oftryptophan and m ethionine. W e do notknow if deficiencies of other single am ino acidsw ould result in a sim ilar fall since the plasm acholesterol level w as not determ ined in ourearlier studies.

The relationship betw een protein intake andthe plasm a cholesterol level is still obscure.In som e hypoproteinem ic states, such as ne-phrosis, hypercholesterolem ia occurs regu-larly, w hereas in the hypoproteinem ia ofkw ashiorkor the cholesterol level is con-sistently low . Experim ents in anim als and inm an on low protein diets have given diam et-rically, opposite results : O lson and his co-

17 observed reduced plasm a choles-terol values, w hereas B everidge et reportedelevated values. B everidge and his co-w orkersattribute this discrepancy to the variations inthe nature of the fat used by O lson et al. This,how ever, fails to explain the results of B agchiet w ho w ere able to confirm the results ofthe O lson group using diets in w hich the fat w askept constant. B oth O lson et al. and B agchiet al. attribute the effects of their low proteindiets to a deficiency of the lipotropic effect ofm ethionine. H ow ever, this w ould not ex-plain our ow n findings, for in our studies theintake of the lipotropic agents, choline andm ethionine, w as kept constant as w ere all theother dietary ingredients. The m atter ob-viously needs clarification.

The changes in the plasm a am inogram in theisoleucine-deficient state reflect the w idespreaddisturbance of am ino acid m etabolism . Thedecrease in isoleucine concentration w as to beexpected, but w hat w as quite as striking, andin s o me c a s e s mo r e s o wa s t h e i nc r e a s e in theconcentration of several other am ino acids,perhaps due to im pairm ent of their utilizationin synthetic processes. Elsew here2022 w ehave described the changes w hich take placein the plasm a am inogram w hen certain essen-tial am ino acids are deficient in the diet. Avariety of com plex patterns are encountered.


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Isoleucine R equirem ents of Infants 321

The changes w hich occur in the case of iso-leucine, how ever, are particularly striking.It w ould appear that the branched chainam ino acids, the arom atic am ino acids and, toa lesser extent, the hydroxyam ino acids sharecertain com m on pathw ays. A m ore com pre-hensive study of these am ino acid interrelation-ships is being pursued at present.

S UMMA R YThe isoleucine requirem ent of six norm al in-

fants has been studied and has been found tolie betw een 79 and 126 m g. per kg. per day.

The w ithdraw al of isoleucine from the dietled to m arked im pairm ent of nitrogen retentionand in som e instances to sym ptom s of nervoussystem involvem ent. A reduction in theplasm a cholesterol w as observed in several in-stances. The am ino acid pattern of theplasm a w as m arkedly altered, the concentrationof isoleucine itself being reduced and that ofcertain other am ino acids increased. N ote-wo r t h y we r e t h e i nc r e a s e d l e v e l s o f t y r o s i nephenylalanine, valine, serine and lysine.

R E F E R E NC E S1 . P R A T T , E . L ., S N Y D E RM A N , S . E. C H E U N G , M . W .,

N O R T O N , P. M ., H O LT , L. E. J R ., H AN SE N , A. E.and P A N O S , T. C. Th e t h r e o n i n e r e q u i r e me n t o ft he n o r ma l i nf an t . J. N utr i ti on, 5 6: 2 31 1 9 55 .

2. S N Y D E RM A N , S . E. P R A T T , E. L., C H E U N G , M . W .,N O R T O N , P. M ., H O LT , L. E., J R ., H AN SE N , A. E.and PA rcos, T . C . T he phenylalanine require-m ent of the norm al infant. N. Nutr i t ion , 57: 253,1958.

3. SNYDERMAN, S . E., NO R T ON , P. M ., F O W L E R , D . I.a n d H O L T , L . E ., JR . T he essential am ino acidrequirem ents of infants: lysine. Am. J. D is.Child., 97: 175, 1959.

4. S N Y D E RMAN , S. E ., H O L T , L. E. J R. , S MEL L 1 E, F.B O V E R , A. a n d WESTALL , R . G . Th e e s s e n t i a lam ino acid requirem ents of infants: valine.Am . J. D is. Child. , 97: 186, 1959.

5. S N Y D E RM A N , S . E. B OY E R , A. a n d H O L T , L . E., J R.T he arginine requirem ent of the infant. Am . J.D is. C hi ld., 97: 192, 1959.

6. S N Y D E RM A N , S . E. R O I T M A N , E . L., B O Y E R , A. a n dH O L T , L . E ., JR . E ssential am ino acid require-m ents of infants: leucine. Am. J. D is. Chi ld.,1 02 : 1 57 1 96 1.

7. SNYDERMAN, S. E., B O Y E R , A ., P H A N S A L K A R , S. V .and H O L T , L . E., JR . Essential am ino acid re-quirem ents of infants: tryptoph an . Am. J. D is.Child., 102: 163, 1961.

8. S N Y D E RM A N , S. E . B O V E R , A . R O I T M A N , E . H O L T ,L . E ., JR . and P R O S E , P. H . T he histidine re-quirem ent of the infant. Pediatrics, 31: 786,1963.

9. PIEz, K . A . and MO R R I S , L. A m odified procedurefor the autom atic analysis of am ino acids. Anal.Biochem., 1 : 187, 1960.

10. S P A C KM A N , D . H ., S T E IN , W . H . and M O O R E , S.A utom atic recording apparatus for use in thechrom atography of am ino acids. Anal. Chem.,31: 1190, 1958.

11. B L O O R , W . R ., P E L K A N , K . F. and A L L E N , D . M .D eterm ination of fatty acids (and cholesterol) insm all am ounts of blood plasm a. J. Biol . Chem.,52: 191, 1922.

12. S N Y D E RM A N , S. E . H O L T , L. E. J R . , D A N c E S, J.,R O IT M A N , E . B O Y E R , A . and BALL S , M . E . U nessential nitrogen : A lim iting factor forhum an grow th. J. N ut ri ti on, 78: 57, 1962.

13. R osE , W . C ., HA INE S , W . J. and WA R N E R , D . T .The am ino acid requirem ents of m an. I I I . T herole of isoleucine am id additional evidence con-cerning histidine. J. Biol . Chem., 193: 605, 1951.

14. R O S E , W . C ., EADE S , C . H ., J R. and C O O N , M . J.T ue am ino acid requirem ents of m an. X I I . T heleucine and isoleucine requirem e nts. J. Biol .Cheiiz.., 216:225, 1955.

15. S W E N D S E ID , M . E . and D uN N , M . S. A m ino acidrequirem ents of young w om en based on nitrogenbalance data. n. Studies on isoleucine. J.Nu tr i t ion , 58: 507, 1956.

16. O L S O N , R . E., J A B L O N S K I , J. R . and T A Y L O R , E .T he effect of dietary protein, fat and choline onthe serum lipids and lipoproteins of the rat.Am . J. C/in. Nutr it ion, 6: 111, 1958.

1 7 . OLsoN, R . E., V E S T E R , J. W ., GU I S E Y , D ., DAV I S ,U . and L O N GM A N , D . E ffect of low proteindiets upon serum cholesterol in m an. Am. J.C /i n. N ut ri ti on, 6 : 3 1 0 1958.

18. B E V E R I D G E , J. M . R ., C O N N E L L , W . F. and R O B IN -SO N , C . Effect of the level of dietary proteinw ith and w ithout added cholesterol on plasm acholesterol levels in m an. J. N ut ri ti on , 79: 289,1963.

19. B A G C H I , K ., R A Y , R . and D A T T A , T . T he influenceof dietary protein and m ethionine on serumcholesterol level. Am . J. C /in. Nutr i ti on, 13:232, 1963.

20. S N Y D E RM A N , S . E ., C U SW O R T H , D . C ., R O I T M A N , E .and H O L T , L . E ., JR . A m ino acid in terrelation -ships. The effect of variations in leucine intake.F ed . P roc., 18: 546, 1959.

2 1 . S N Y D E RM A N , S . E. H O L T , L. E., J R . , NO R TO N , P.and R O I T M A N , E . A m in o acid in terrelation ships.F ed. Pr oc., 19: 12, 1960.

2 2 . H O L T , L . E ., JR S N Y D E RM A N , S . E. N O R T O N , P .M ., R O I T M AN , E . and F I N C H , J. T he plasm aam inogram in kw ashiorkor. Lancet, 2 : 1 3 4 3 .1963.

Snyderman Et Al 1964 the Essential Amino Acid Requirements of Infants_isoleucine

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Transcript of Snyderman Et Al 1964 the Essential Amino Acid Requirements of Infants_isoleucine