Arq. NeuroPsiquiatr. vol.24 número1

METABOLISM OF FAT IN SUBACUTE COMBINED DEGENERATION

OF THE SPINAL CORD

H O R A C I O M . C A N E L A S * N E L S O N D E C A R V A L H O * * A R N A L D O G A M A D A R O C H A *

The white matter of brain contains 60 per cent of fat, half of them

being myelin lipids (Autilio et a l .

) . In the lipid layers of the lamellae of

the myelin sheat the molecules of cholesterol, galactolipids (cerebrosides)

and phospholipids (sphingomyelin) are arranged in a definite architectonic

pattern (Hills and S p e c t o r

) .

T h e demyelinating diseases could be ascribed to some abnormality in

the processes of repair and reposition of myelin (Sperry and W a e l s c h

) .

A t the eighth day of wallerian degeneration an accumulation of cholesterol

esters is already found ( A d a m s

) ; the synthesis of phospholipids is also

in-creased ( S m i t h

) , owing probably to the proliferation of the Schwann cells.

In allergic experimental encephalomyelitis the metabolism of cholesterol is

little changed, but the synthesis of galactolipids and phospholipids is

in-creased

; yet in old lesions, similar to those of multiple sclerosis, a decrease

of phospholipid and the presence of cholesterol esters w e r e found (Cumings

) .

Laboratory studies on the lipid metabolism in the demyelinating diseases

are almost limited to the researches in multiple sclerosis. T h e results of

the numerous investigations on the lipid metabolism in this d i s e a s e

are

not always agreeing. Lafontaine

>

found an increase of the phospholipid

and cholesterol levels both in the blood and cerebrospinal fluid. Bernsohn

and N a m a j u s k a

found lower concentrations of the blood phospholipids in

their patients than in normal subjects. Gerstl et a l .

, studying the dienoic

fatty acids of the blood serum, found lower concentrations in the patients

with active disease than in those in the inactive state. P l u m and F o g

,

however, failed to demonstrate any definite variation of the blood contents

of total lipids, total cholesterol and phospholipids in patients with multiple

sclerosis and in their normal material. Green et a l .

found an increase of

the cerebrospinal fluid concentration of cholesterol (mostly in the esterified

R e a d a t t h e F i r s t I n t e r n a t i o n a l S y m p o s i u m o n N u c l e a r B i o l o g y a n d M e d i c i n e , h e l d in S ã o P a u l o , B r a z i l , S e p t e m b e r 20-25, 1964.

fraction), which w a s correlated with the degree of functional deficit of the

patients. Sercl et a l .

found a decrease of the phospholipids and esterified

cholesterol in the blood of patients, while no variation in the concentration

of total or free cholesterol w a s evidenced. B a k e r et a l .

found a significant

reduction of the percentage of linoleic acid, particularly when the neurologic

conditions w e r e worse.

In subacute combined degeneration of the spinal cord ( S C D S C ) the

in-vestigations on the fat metabolism are scarce. C a r r e g a et a l .

found high

levels of phospholipids and cholesterol in the cerebrospinal fluid. Canelas

found an increase of the phospholipid content in the blood serum, while the

blood cholesterol levels w e r e normal. I n a case studied by Green et a l .

the cholesterol in the cerebrospinal fluid w a s increased, mostly in the free

fraction.

M u l l e r

, M i e t t i n e n

, and P a l v a

found low concentrations of blood

cholesterol in cases of vitamin B

deficiency; the fact w a s correlated by

P a l v a to the decrease of coenzyme A activity in liver

, which could hinder

the synthesis of the lipidic coats of axons and red blood cells. Some

inves-tigations actually demonstrate that the antianemic treatment yields an

in-crease of the cholesterol and phospholipid contents of the blood serum

»

.

Besides these disorders of the lipid metabolism, in S C D S C an

impair-ment of the intestinal absorption occurs. These alterations are sometimes

not restricted to deficient absorption of vitamin B

and affect other

meta-bolic fields, giving rise to malabsorption syndromes, frequently without

evi-dent abdominal manifestations, in a form name "cryptic" by Spillane and

W e l l s

.

W i t h the purpose of investigating this matter, in 10 cases of S C D S C

the absorption, clearance and utilization of labeled fat was studied. T h e

relationship between the pattern of the neurologic manifestations and the

disorder of fat metabolism was also analysed.

M A T E R I A L A N D M E T H O D S

Material — T e n cases o f S C D S C h a v e b e e n s t u d i e d . T h e d i a g n o s i s w a s b a s e d

o n t h e f o l l o w i n g c r i t e r i a : ( a ) C h a r a c t e r i s t i c n e u r o l o g i c p i c t u r e , a l w a y s r e p r e s e n t e d , t h o u g h in v a r i e d d e g r e e , b y s i g n s o f p e r i p h e r a l n e r v e i n v o l v e m e n t ( d y s e s t h e s i a s , m u s c l e tenderness, h y p o a c t i v e o r a b s e n t d e e p r e f l e x e s , h y p o t o n u s , p e r i p h e r a l c u t a -n e o u s h y p e s t h e s i a ) a -n d a d o r s a l f u -n i c u l i s y -n d r o m e ( i m p a i r m e -n t o f d e e p se-nsatio-n, R o m b e r g ' s sign, a t a x i a o f t h e e x t r e m i t i e s ) , a n d in 8 cases b y a p y r a m i d a l s y n d r o m e ( B a b i n s k i ' s s i g n and, e v e n t u a l l y , w h e n t h e p e r i p h e r a l i n v o l v e m e n t w a s v e r y m i l d , h y p e r a c t i v e d e e p r e f l e x e s , c l o n u s a n d a u t o m a t i s m s ) . T h e c e r e b r o s p i n a l f l u i d e x a -m i n a t i o n d i s c l o s e d n o a l t e r a t i o n in t h e c e l l c o u n t ; r e g a r d i n g t h e t o t a l p r o t e i n c o n t e n t , o n l y in case 3 a s l i g h t i n c r e a s e w a s f o u n d , ( b ) G a s t r i c a c h l o r h y d r i a in a l l cases, h i s t a m i n e - f a s t in 9; in a l l cases b u t o n e ( c a s e 4, s u b m i t t e d t o p a r t i a l g a s t r i c r e s e c t i o n ) t h e a n a c i d i t y w a s c o n s t i t u t i o n a l , ( c ) C h a n g e s o f t h e p e r i p h e r a l b l o o d in t h e sense e i t h e r o f a m a c r o c y t i c ( 2 c a s e s ) o r a n i r o n - d e f i c i e n t a n e m i a ( 3 c a s e s ) , ( d ) S i g n s o f i n h i b i t e d m a t u r a t i o n a t t h e b o n e m a r r o w e x a m i n a t i o n o f 3 cases.

Methods — T h e neurologic i n v o l v e m e n t w a s e v a l u a t e d in a s e m i q u a n t i t a t i v e

w a y6

T h e absorption of radioactive (Co57

) vitamin Blt w a s s t u d i e d t h r o u g h t h e S c h i l l -i n g ' s u r -i n a r y e x c r e t -i o n t e s t2 1

; l e v e l s l o w e r t h a n 10 p e r c e n t w e r e c o n s i d e r e d as a b n o r m a l a n d in a l l cases b u t o n e , a s e c o n d t e s t w i t h t h e a s s o c i a t i o n o f i n t r i n s i c f a c t o r * w a s p e r f o r m e d .

Triolein o r oleic acid l a b e l e d w i t h 20 fiC o f I1 3 1

w a s d i l u t e d t o a v o l u m e o f 10 m l w i t h c a r r i e r t r i o l e i n o r o l e i c a c i d . T h e f a t o r f a t t y a c i d w a s t h e n a d d e d t o w h o l e m i l k t o m a k e a v o l u m e o f 200 m l . T h i s m i x t u r e w a s h o m o g e n i z e d in a b l e n d e r f o r 5 m i n u t e s , a t w h i c h t i m e i t w a s u n i f o r m l y suspended. M i l k w a s used as a c a r r i e r f o r t h e l a b e l e d f a t in o r d e r t o m o r e c l o s e l y a p p r o x i m a t e a p h y s i o l o g i c a l l y s t a b i l i z e d f a t e m u l s i o n . A f t e r a 12-hour f a s t e a c h p a t i e n t w a s g i v e n a t e s t m e a l a n d v e n o u s b l o o d s a m p l e s w e r e t a k e n in a h e p a r i n w e t t e d s y r i n g e 2, 4, 6 a n d 24 h o u r s l a t e r . A 5 m l a l i q u o t o f u n c l o t t e d b l o o d w a s c o u n t e d in a s c i n t i l l a t i o o n w e l l c o u n t e r ( w h o l e b l o o d r a d i o a c t i v i t y ) . A n o t h e r a l i q u o t , t r e a t e d w i t h p o t a s s i u m i o d i d e a n d t r i c h l o r o a c e t i c a c i d t o s e p a r a t e t h e l i p o p r o t e i n - b o u n d i o d i n e , w a s a l s o a s s a y e d f o r r a d i o a c t i v i t y . T h e t o t a l b l o o d v o l u m e w a s a s s u m e d t o be 7.2 p e r c e n t o f t h e b o d y w e i g h t . W i t h t h e g i v e n a c t i v i t y in t h e 5 m l p o r t i o n s a n d t h e c a l c u l a t e d t o t a l b l o o d v o l u m e , t h e t o t a l w h o l e b l o o d a n d l i p i d b l o o d r a d i o a c t i v i t y w e r e d e t e r m i n e d a n d e x p r e s s e d as. a p e r c e n t a g e o f t h e i n g e s t e d f a t ( % D ) . T h e t o t a l u r i n e o u t p u t w a s c o l l e c t e d f o r 72 h o u r s a n d t h e s t o o l s w e r e a l s o c o l l e c t e d o v e r t h e s a m e p e r i o d .

A f t e r i n g e s t i o n o f a t r i o l e i n o r o l e i c a c i d t e s t m e a l , t h e m e a n w h o l e b l o o d r a d i o a c t i v i t y u s u a l l y i n c r e a s e s b y t h e 4t h

o r 6t h

h o u r t o a p e a k v a l u e o f 12 p e r c e n t ( l i p i d b l o o d v a l u e , 4 p e r c e n t ) , a n d t h e n g r a d u a l l y w a n e s so t h a t a f t e r 24 h o u r s n e a r l y 2 p e r c e n t ( l i p i d b l o o d v a l u e 0.2 p e r c e n t ) r e m a i n s . T h e o r g a n i c f r a c t i o n r e p r e s e n t s less t h a n 50 p e r c e n t o f t h e t o t a l . U r i n e c o l l e c t i o n s o f 72 h o u r s c o n t a i n b e t w e e n 20 a n d 40 p e r c e n t o f t h e a d m i n i s t e r e d r a d i o a c t i v i t y , a n d t h e a v e r -a g e f e c -a l r -a d i o -a c t i v i t y o v e r t h i s p e r i o d is u s u -a l l y less t h -a n 2 p e r c e n t .

R E S U L T S

F o u r cases ( N o . 2, 4, 5 and 7 ) s h o w e d d i s o r d e r s o f f a t m e t a b o l i s m : in 2 o f t h e m a d e f i c i e n t a b s o r p t i o n t h r o u g h t h e i n t e s t i n a l w a l l w a s d e m o n s t r a t e d , 3 cases s h o w e d a n i m p a i r e d c l e a r a n c e o f f a t , a n d 2 h a d a d e c r e a s e d u t i l i z a t i o n o f f a t ( T a b l e 2 ) ; 3 cases h a d s t e a t o r r h e a . I n 3 o f t h e s e 4 cases a p r e v i o u s d i a g n o s i s o f m a l a b s o r p t i o n s y n d r o m e w a s m a d e t h r o u g h t h e S c h i l l i n g ' s t e s t . T h e m o r e s e v e r e

d i s o r d e r o f f a t m e t a b o l i s m w a s f o u n d in a p a t i e n t w h o h a d b e e n s u b m i t t e d t o p a r t i a l g a s t r i c r e s e c t i o n . I n c a s e 7 a d e f i c i e n c y o f i n t r i n s i c f a c t o r such as is seen in p e r -n i c i o u s a -n e m i a h a d b e e -n e v i d e -n c e d .

T h e m e a n u r i n a r y e x c r e t i o n o f l a b e l e d v i t a m i n B1 2 in t h e 4 cases s h o w i n g

dis-o r d e r s dis-o f l i p i d m e t a b dis-o l i s m w a s 5.05 p e r c e n t ± 3 . 3 6 . I n t h e r e m a i n i n g 6 cases w i t h n o r m a l f a t m e t a b o l i s m t h e m e a n w a s 6.09 p e r c e n t ± 5 . 8 1 . T h e d i f f e r e n c e b e t w e e n t h e s e m e a n s w a s n o t s i g n i f i c a n t (t = 0 . 3 2 ) .

T h e s t a t i s t i c a l a n a l y s i s o f t h e d i f f e r e n c e s b e t w e e n t h e a v e r a g e s o f t h e p e r i -p h e r a l , d o r s a l f u n i c u l i a n d -p y r a m i d a l s y n d r o m e s in t h e g r o u -p s w i t h i m -p a i r e d a n d n o r m a l lipid m e t a b o l i s m d i s c l o s e d n o s i g n i f i c a n t v a l u e s ( T a b l e 3 ) . I n s p i t e o f t h i s r e -sult, w h i c h is m o s t l y d e r i v e d f r o m t h e l i t t l e s i z e o f t h e s a m p l e , i t c a n b e seen t h a t t h e p e r i p h e r a l a n d d o r s a l f u n i c u l i s y n d r o m e s w e r e m o r e s e v e r e i n t h e 4 cases w i t h d i s -o r d e r s -o f f a t m e t a b -o l i s m t h a n in t h e n -o r m a l cases, w h i l e t h e p y r a m i d a l s y n d r -o m e w a s a l m o s t t h e s a m e in t h e t w o g r o u p s . T h e w h o l e n e u r o l o g i c a l p i c t u r e w a s a l s o m o r e s e v e r e in t h e 4 cases w i t h i m p a i r m e n t o f f a t m e t a b o l i s m .

D I S C U S S I O N

hap-pens with the absorption of vitamin B

. W e have actually found that the

deficiency of cyanocobalamine absorption in S C D S C is mostly correlated to

the degree of involvement of the corticospinal tracts, while the signs of

damage of the peripheral nerves a n d / o r the dorsal funiculi keep no

rela-tionship with i t

.

.

These results seem to indicate that the impairment of lipid metabolism

evidenced in this study of S C D S C bears no direct relationship with the

de-myelinating process in general, and would rather attend the deficiency of

metabolites (probably the vitamins of the B-complex) other than vitamin

B

, which play a more significant role in the preservation of the peripheral

nerves. This is in full agreement with the well known fact that the B

-complex avitaminoses usually produce a peripheral neuropathy only, the

in-volvement of the central nervous system being exceptional.

S U M M A R Y

In 10 cases of subacute combined degeneration of the spinal cord the

absorption, clearance and utilization of labeled fat w a s studied. In 4 cases

disorders of the lipid metabolism w e r e found.

Although not significantly, the peripheral and dorsal funiculi syndromes

w e r e more severe in the 4 cases with impaired fat metabolism than in the

normal cases, while the pyramidal syndrome was almost the same in the

two groups. T h e whole neurological picture w a s also more severe in the

4 cases with disorders of fat metabolism.

These results seem to indicate that the impairment of lipid metabolism

evidenced in such cases bears no direct relationship w i t h the demyelinating

process in general, and would rather attend a deficiency of metabolites

(probably B-complex vitamins) other than vitamin B

, which play a more

significant role in the preservation of the peripheral nerves.

R E S U M O

Metabolismo dos lípides na mielose funicular

E m 10 casos de mielose funicular foram estudadas a absorção, a

depu-ração e a utilização de lípides radioativos. E m 4 desses casos foram

veri-ficadas alterações do metabolismo lipídico.

E m b o r a não significantemente, as síndromes periférica e funicular

dor-sal mostraram-se mais intensas nos 4 casos com distúrbios do metabolismo

lipídico que nos demais, enquanto a síndrome piramidal foi

aproximada-mente semelhante nos dois grupos de pacientes. A sintomatologia

neuro-lógica global também se apresentou mais intensa nos 4 casos com alterações

do metabolismo lipídico.

que desempenhariam papel mais importante na preservação dos nervos

pe-riféricos.

R E F E R E N C E S

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