Microencapsulation of the enzyme phenylalanine ammonia-lyase (PAL) was developed for in vivo depletion of systemic phenylalanine (PHE) in Phenylketonuric (PKU) rats. Phenylalanine ammonia-lyase was successfully microencapsulated within artificial cells. The immobilized enzyme had an assayed activity of 20% $ pm$ 4% (Mean $ pm$ S.D.) of the free enzyme in solution. The immobilized enzyme maintained a higher enzyme activity at very low pH compared to the free enzyme in solution. The pH optimum of the free and immobilized enzyme was 8.5. This pH optimum corresponds to the average pH range of the small intestine. / PKU induced rats had a 10 to 20-fold increase in the amino acid phenylalanine in the systemic circulation. This amino acid elevation was comparable to the plasma phenylalanine increase in human PKU patients. Daily oral administration of artificial cells containing 5 units of the enzyme PAL, to PKU rats, lowered on an average the systemic phenylalanine level to 20% $ pm$ 8% (Mean $ pm$ S.D.) of the original levels in 7 days (P $<$ 0.001). After 7 days of this form of enzyme therapy, systemic blood phenylalanine levels of PKU treated rats were lowered to levels not significantly different from those of normal rats. Unlike control PKU rats, the treated group showed no signs of abnormal behavior or weight loss. / HPLC analysis of free amino acids in the plasma, cerebro-spinal fluid and brain of PKU rats was carried out in the following groups: (1) Normal rats, (2) PKU rats on a normal diet, (3) PKU rats on a high phenylalanine diet, (4) PKU rats on a phenylalanine free diet, and (5) PKU treated rats with PAL-loaded artificial cells. Amino acid compartmental distribution was different in all these groups. / The oral administration of PAL-loaded artificial cells decreased the hyperphenylalaninemia in all the compartments studied. It also corrected the imbalance of many amino acids, including tyrosine and tryptophan, in the CSF and the brain. This enzyme therapy was more effective in compartmental PHE level depletion, than a PHE-free diet.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.74364 |
| Date | January 1987 |
| Creators | Bourget, Louis A. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Physiology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001233139, proquestno: AAINN64105, Theses scanned by UMI/ProQuest. |
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