Auxilliary liver transplantation (ALT) in jaundiced Gunn rats with normal hepatobiliary transport function and in gunn rats with a hepatic excretion defect

PB-1

HETEROGENEITY

OF PORPHOBILINOGEN

DEAMINASE

IN ACUTE INTERMITTENT

PORPHYRIA

JHP Wilson, FWM de Rooij, K te Velde, Department of Internal Medicine II, Erasmus University, Rotterdam and Department of Internal Medicine, St. Geertruiden Hospital, Deventer, The Netherlands. Acute Intermittent Porphyria is due to an inherited defect in haem biosynthesis at the level of the enzyme porphobilinogen deaminase. To determine the occurrence of heterogeneity of AIP, we measured porphobilinogen deaminase (PBG-D) activity and cross reacting immunological material (CRIM) using antibodies raised against PBG-D in erythrocytes from 76 Dutch patients with AlP, from 107 healthy controls and from over 2000 relatives of AIP patients. FBG-D was also separated into fractions based on pl by FPLC and activity and CRIM measured in the fractions. Results: Most AIP patients had PBG-D levels approximately 50 % of controls. There was a bimodal distribution of activity in their relatives. In 3 families with otherwise classic AlP, patients had normal PBG-D activity in erythrocytes and a unimodal distribution in their relatives. In the families with reduced erythrocyte PBG-D activity, three variants were found based on the antibody studies. One is characterized by an equivalent reduction in both catalytic and CRIM PBG-D. Some families showed a CRIM:activity ratio of ].5 in patients, and 2 families had a ratio of approximately 5. Following separation of PBG-D according to pl by FPLC, the excess CRIM was found to have similar pl's to normal stable enzyme-substrate intermediates, whereas a normal CRIM:catalytic activity ratio was found for the free enzyme. Conclusion: There are at least 4 subtypes of AlP: ]) 50 % reduction in erythrocyte PBG-D activity and CRIM, 2) normal erythrocyte PBG-D levels, 3) ].5 x more CRIM than catalytic activity and 4) 5 x more CRIM than catalytic activity. In types 3 and 4 the enzyme appears to bind porphobilinogen in a fashion which does not allow completion of the normal reaction but which in some way stabilises the enzyme protein and makes it resistant to breakdown.

PB-2

AUXILLIARY LIVER TRANSPLANTATION (ALT) IN JAUNDICED GUNN RATS WITH NORMAL HEPATOBILIARY TRANSPORT FUNCTION AND IN GUNN RATS WITH A HEPATIC EXCRETION DEFECT, PLM Jansen t F Hess~ WHM Peters~ E Koenders~ FHM Corstens. D i v . o f G a s t r o e n t e r o l o gy, C y t o - H i s t o I o ~ y , Nuclear Medicine. St. Radboud U n i v e r s i t y H o s p i t a l Nijmeqen, The N e t h e r l a n d s . A r e c e n t I y d e s c r i b e d h e p a t o b i I i a r y e x c r e t i o n d e f e c t i n r a t s ( H e p a t o ] . 1985; 5: 5739) was bred i n t o Gunn r a t s (GR) w i t h unconjuqated h y p e r b i ] i r u b i n a e m i a to produce a s t r a i n w i t h both UDPg ] u c u r o n y l t r a n s f e r a s e d e f i c i e n c y and d e f e c t i v e h e p a t o b i l i a r y t r a n s p o r t ( d o u b l e mutants, DM)~ These r a t models were used to t e s t ALT f o r t r e a t m e n t o f g e n e t i c d i s e a s e s . A f t e r p a r t i a l hepatectomy and r i g h t nephrectomy about equal sized I i v e r segments from normal r a t s were i m p l a n ted in the r i g h t renaI fossa o f c y c l o s p o r i n - t r e a t e d r e c i p i e n t animals. P o r t a l and h e p a t i c v e i n s o f donor l i v e r were connected t o p o r t a l and cava] v e i n s o f r e c i p i e n t and a h e p a t o j e j u hal anastomosis was c o n s t r u c t e d to a l l o w b i ] i a r y d r a i n a g e o f the g r a f t e d l i v e r . Three weeks a f t e r ALT serum b i I i r u b i n had decreased from 190±15 t o 24±6 ~M i n 7 GR and from 230±10 t o 30±10 M i n 6 DM. Twelve weeks a f t e r ALT b i l i r u b i n had decreased t o 10±3 pM i n 4 GR and t o 5±3 ~M i n 4 DN. One GR had d i e d . In 2 GR and 2 DM unconjugated b i l i r u b i n was e l e v a t e d again i n d i c a t i n g i n s u f f i c i e n t c o n j u g a t i o n f u n c t i o n o f t h e t r a n s p l a n t . One DM had i n c r e a s e d conjugated bi]irubin indicating insufficient e x c r e t i o n f u n c t i o n o£ the t r a n s p l a n t . Liver s c i n t i g r a p h y w i t h 99mTc-HIDA was done i n a l l animals and e x c e l l e n t t r a n s p l a n t f u n c t i o n was seen i n 4 GR and 4 DM. In q e n e r a l , DM d i d b e t t e r a f t e r ALT than GR: 12 weeks a f t e r ALT DM had gained w e i g h t t o 113±2% and GR had I o s t t o 84±3% o f preop, w e i q h t . L i v e r f u n c t i o n o f both t r a n s p l a n t and r e c i p i e n t I i v e r was s t u d i e d i n acute e x p e r i m e n t s i n which b i l e ducts werecann u ] a t e d o f both r e c i p i e n t and donor l i v e r . T r a n s p l a n t s i n DM produced more b i l e (2x) and had h i g h e r b i ] e a c i d (2x) and b i l i r u b i n e x c r e t i o n r a t e s (4x) than t r a n s p I a n t s i n GR. This sugqests t h a t f u n c t i o n s ] c o m p e t i t i o n between r e c i p i e n t and donor ] i v e r i s i m p o r t a n t f o r t r a n s p l a n t f u n c t i o n : r a t s w i t h the e x t r a handicap o f a h e p a t o b i l i a r y e x c r e t i o n d e f e c t did b e t t e r a f t e r ALT than r a t s w i t h U D P q ] u c u r o n y I t r a n s f e r a s e d e f i c i e n c y o n l y .

$57