2. Sacar fruto del invernadero
4.2 Análisis para Injerto
There
i sextensive s
well ing of the Fananas · ce l l s , ' adjacent to the Purkinj e neurones, whichpre sumably
correspond t o theBergman
glial cells seen by light microscopy.seen
rather difficult to r ec onc ile wi th the ultras truc tur al findings in the p r e s e n t s tud y . I n his acute c a s e s h e describ e d " • • • walls of the more sever e l y affec t ed ar t erioles had a homogene ous
e os in ophilic app earance • • • • • swollen h ypo c hroma t i c endothelial c e lls w e r e o c c 3.sionally observed . " In his subac ute c a s e s he f ound
1 1 • • • • c apillary W3.lls appeared to be h yalinis e d and the endotheli al c a l ls were swollen And h ypo chromati c . 11 The pr esent s tudy d i d not r eveal any d e te c table swelling of e n d o the lium wh en i t was e xamined with e i ther the light or the elec tron microsc ope and there was no obvious involv a me n t o f the basement membranes.
Woodbur y e t al ( 1 956 ) fo und tha t 70% o f a group o f mi c e d i e d
when sub j e c te d t o a n at mosph e r e in whi c h t h e par tial p r e s s u r e
o f
oxygen had b e en r e duc e d t o 76mmHg i e 1 0% oxygen. I t should be
n o t e d that it i s extremely d i ff i c ul t to maintain e xperimen tal animals
in an atmosphere with a reduc e d oxygen t e ns i on , when the c arrier gas
is n i t r ogen , as the animals go into acute c onvul s i ons and die.
Thi s i s a prob l em which has b e en e nc oun tered b y workers inve s t igating the e f fec t o f h yp o xia on brain oedema ( Levine 1 960 ) . N i tr ous oxide app ears to b e a much less cri tical carrier gas than n i tr ogen and
from the eviden c e of the pr e s ent s tudy it does ne t appear tu pr oduc e
any morphologi c al changes in the brain whe n i t i s used wi th a
par tial pr e ss ur e of oxygen appruaching tha t in the n ormal
a tmosphe re .
In v i e w 0 f the s everi ty o f th e c apillary enda the lial damage
it i s n o t surpris ing tha t the horse r adish p�rcxidase, whi c h is a
small protein wi th a molec ular weigh t of 40 , 000 , c uuld e s c ap e from
the bloods t r e am into the e x trace llular spac e s wi thin the neuropi l ,
and i ts use has provided v is ual c onfirmation o f Gri n e r ' s ( 1 96 1 b )
finding that pro teins e scape i n t o the b rain subs tanc e in intoxicated
animals . The d i s tribution of the trac er is s imilar t o that f ound in exper ime n tal brain oedema produ c e d by o ther workers ( Hirano � al 1 970 ) .
This finding i s o f impor tance whe n the s ta tus o f p lasma
7 5
more fully in Chapter 1 6 . I t i s interes t ing t o n o t e that , although the peroxidase e sc aped in t o , and was c onfined to , the t enuous
extrac e l lular spac e s be t we e n the c e ll pr o c esses of the neuropil , the r e was ne eviden c e o f e x c e s s fluid in this r egi o n and the fluid ac cumulation which occured during intoxication appe ared to b e
nlmos t e ntire ly intrac ellular . I t is unfortunate tha t the leve l of peroxidase used in the lambs was n o t de t e c tab le . The r e sult was
not altoge ther surprising however , sinc e the dose rate is
c onsi derably below that rec ommended for mice and rats on a body weigh t basis. To provide an equivalent amount for lamb s would nec e ss i tate using a dose of the order of 4 grams or more. Although fluo r e s c ein- con jugated pr o t e ins have b e e n used in permeab i li t y
s tudie s the y canno t be employed f or ultras truc tural visualisation and t o date no te chniques whi ch are entirely satis fac tory for use in lar g e r animals have b e e n d e scribed.
The earlie s t lesions d e t e c table in the c er e b ellar granular layer b y light microscopy ar e dire c tly r e f erab le to the change s
s e en b y elec tron micr osc opic examinati on. The f o c al are as of rar e fac tion ar e almos t c e r tainly areas i n which the s w elling o f the as troc y tes i s m o s t m�rked. Th e very focal nature of the s e lesi ons and the les i ons which develop in the whi te mat t e r made it difficult
to r e late them dir e c tly to the ultras truc tural changes. The
s eque n c e of chanse s which d evelop over a period o f time in the brains o f i n toxic ated animals , have been adequately described by Griner
( 1 96 1 a ) . They need not c on cern us here since they r esult from t i s s u e damage sub s e quent to the ac tion o f eps i l on toxin r a ther than from any direc t effec t of the t oxin i ts e lf .
The histo chemical f indings mus t b e menti oned b r i e fly . ct &,,. .... Q ""
B e c kerA (1 96 1 > 6 z ) hav e shown tha t reduc tions in the levels o f acid
phosphatase , as well as o ther enzymes , oc cur in animals in which anoxic -ischaemic enc ephalopathy has been induc e d . Th e ear lie s t time a t which these change s were de tec table was 6- 1 2 hours and i t is obvious that , b e c ause o f the acute natur e o f epsilon t oxin i n t oxication in lamb s , few his tochemical changes could have b e e n expec ted .
Conc lu s i ons
1 . I n mi c e , e p s ilon t o xin p r o du c e s an i n c r e a s e in bruin water c on t e n t wh i c h b e c om e s g r e a t e r with i n c r e as i n g surv ival t i m e . S i mi lar changes c ou l d n o t b e d a muns tr � t e d in lambs as t h e s u r v i v a l time was shor t i n i n t o x i c a t e d snima l s .
2 .
The i n c r � a s e in brain w a t e r c on t e n t in i n t o xi c a t e d mic ewas as s o c i a t e d wi th morphologi c al e v i d e n c e o f o e d e m a in t h e gr e y m a t t e r o f the brai n , wh e r e s welling o f a s t r o c y t e s and as tr o c y t e pr o c e s s e s w a s pr omi n e n t .
i n t oxic a t e d lamb s .
The s e c h a n g e s w e r e also pr e s e n t i n t h e
3 .
Ext e n s i v e d e s tr u c t i o n o f v a s c ular e n d o t h elium o c c ur r e d i n a l l i n t oxic a t e d anim als a n d r e s u l t e d in the l o s s o f f luid a n dp r o t e i n i n t o the b r ain t i s su e .
4 , Th e u s e o f hor s e radi s h p e r o x i d a s e as a trac er
c onfirmed t h e loss o f p r o t e i n from t h e blood s tr e am of i n t ox i c a t e d m i c e a n d s h o w e d t h a t i t was c on f i n e d t o the e x t ra c e l lular spac e wi thin t h e n europil and d i d n o t e n t er the s w o l l e n as tr o c y t e
proc e s s e s . Per o x i da s e giv e n a t a d o s e o f 1 00mg i n trav e no u s l y was n e t d e t e c t ab le i n e i t h e r c o n t r o l or i n t o x i c a t e d lamb s .
5 .
Th e c h a n g e s indu c e d b y e p s i l o n toxin w e r e n o t t h e r e sult o f t i s sue h yp o xi a s i n c e animals w h i c h d i ed from c r i ti c al h ypoxia s h o w e d n u v a s cu lar d amage or s w e lling o f a s tr o c y t e s and had n e ur onal c h anges wh i c h were n o t pr e s e n t in i n t o x i c a t e d animal s .6 . N i t r o u s oxide i s a more s ui t ab l e c arri e r gas than
n i t r og e n for s t ud i e s o f the e f f e c t s of h ypoxia on mi c e and does n o t p r o d u c e c li ni c al d i s turbanc e o r morph o l o g i c al c ha n g e i n t h e ab s e n c e of h yp ox i a .
7 . The e a r l i e s t brain l e s i o n s , d e t e c table b y l i gh t
m i c r os c opy , oc c ur r e d i n t h e c er e b e ll�r granular layar wh e r e f o c al c ytoplas m i c c le a r i n g and nuc l e ar pykn o s i s o c c u r r e d . Th e s e c hang e s
were p r o b ab l y t h e r e su l t o f the a s t r o c y t ic chan g e s s e en a t t h e ul tras truc tural l e v e l .
8 .
No a l t e r a t i ons i n the l e v e l s of a c id o r alka l i n e/
77
pho sphatas e , DPN or TPN diaphor as e w e r e d e t e c tab l e his t o c h e mi c ally i n intoxi c a t e d animals.
9. The his t o c h em i c a l l o c a l i s a t i o n of t h e s e c c mp o n e n t s :1ncl the pr e s e r v a t i o n o f ar c h i t e c tur e i n l amb b rain was impr oved b y c ol d f ormal c a l c i um f i xati u n and s u c r o s e/a c a c i a infi l t r a t i on w h e n t h e r e s u l t s ob tai n e d with the u s e o f t h e s e age n t s were c ompar e d wi t h t h s s e ob t a i n ed b y que nching f r e s h mouse b r a i n in d r y i c e .
•
Chapter 9 : THE MORPHOLOGI CAL .ASPECTS OF THE PULHONARY AliD MYOCARDIAL OEDEMA
V/HICE OCGiTHS
IN EXPEHIMElrrAL El?I'EROTOXAE1·1liA .One of the prominent fea tures of the t,rross pathological findings in intoxicated animals i s the pulmonary oedema mentioned in Chapters 6 and 7 . I t was obvious that pulmonary oe dema was not consi stently present in
experimentally intoxicated animal s , nor was i t a pro:ainent feature of the na tural disease in sheep.
In view of the vascular endothelial damage i n both the brain and
kidney i t ap_peared probable that
this
was a univer sal phenomenon whichoccurred throughout the body and that the presence or ab sence of oedema <"'f the lungs .-;as dependent upon the severi t;>r of the vascular damage in tho s e
organs. It ,·,ras therefore o f intere st to determine 'i.'hether endothel ial
damage did in fact occur in the lungs of intoxi cated animal s and vrha t
other changes we present i:!'l lung ti s sue. AJ1y cl.a.mage to pulmonary
archit e c ture could affect biochemical parameters as sociated with respira
tory exchange , but these wil l be di scussed in Cl:apter 17 .
The presence of peri cardial effusions anc. electrocardiographic evidence of myocardial damage sugge sted that the heart had no t escaped from the effects of the toxin. Any attempt to interpret electrocardio graphic changes on a morphol ogical basi s is difficu l t since the electrical change s may be transient as exemplified by the regres s i on in the S-T s eg
ment change s in the s e cond post-intoxication ECG tr2.cing taken from LYab no .
63
in Table ? . la , Chap ter 7 . Further , in many instance s ECG altera tions are not associ2. ted with detectable morphological <lEunage. lim;ever the presence of evidence of a repolari sation defect in many of the ECG 1 s sugge sted that there may be myocardial injury or interference wi th ionic or ruetabolite transfer between the intra and extracell11lar compartm�nts of the myocardium in intoxicated a11imal s. I f a morphological bas i s for the electrocardiographic change s c ould be establi shed this would not only provide a useful clinicopathol ogical relationship but would also a s s i s t in increasing the available information on electrocardiographi c change s i11 acute myocardial damage •The in the of Toxin Intoxicated
& Methods