No description available.

ABSTRACT MORPHINE BIOTRANSFORMATIONS BY MICROBIAL PHENOL OXIDASES Erdural Korkmaz, Beril M.S., Department of Chemical Engineering Supervisor: Prof. Dr. Ufuk Bakir Co-Supervisor: Prof. Dr. Ayhan S. Demir January 2006, 96 pages The objective of this study is to perform morphine biotransformation by using phenol oxidases. Syctalidium thermophilum, Thermomyces lanuginosus and Phanerochaete chrysosporium cells and culture fluid were used as microbial intracellular and extracellular phenol oxidases. Besides the phenol oxidases produced in laboratory, commercial pure phenol oxidases, A. bisporus tyrosinase and laccase, T. versicolor laccase and horseradish peroxidase, were also used in the morphine biotransformation reactions. Morphine biotransformation to pseudo-morphine was achieved by using pure T. versicolor laccase, A.bisporous tyrosinase and laccase. Before utilization of phenol oxidases in morphine biotransformations, the time course of microbial phenol oxidase productions were followed. Maximum phenol oxidase activity of S. thermophilum were detected on the 5th day of cultivation as 0.17 U/ml and the 4th day of cultivation as 0.072 U/ml, respectively. On the other hand, maximum laccase activity of P. chrysosporium was detected on the 8th day of cultivation as 78.5 U/ml. Although phenol oxidases which were obtained from S. thermophilum or T. lanuginosus could not catalyze morphine biotransformation, phenol oxidases including a peroxidase of P. chrysosporium transformed morphine to pseudo-morphine and an unknown product.

published_or_final_version / Pharmacology / Doctoral / Doctor of Philosophy

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

No description available.

States of abnormal pain induced by injuries to peripheral nerves share common features with opioid antinociceptive tolerance including mechanical and thermal hypersensitivity. Sustained administration of morphine in humans and in animals induces a state of abnormal pain (i.e., hyperalgesia) and may be associated with the development opioid antinociceptive tolerance. Persistent neuropathic pain states and opioid induced abnormal pain require descending facilitation arising from the rostral ventromedial medulla (RVM). Cholecystokinin (CCK), a pronociceptive peptide, may be up-regulated following opioid treatment and nerve injury in the brain and spinal cord. Therefore, it is hypothesized that CCK in the RVM may be up-regulated by sustained opioid administration and my consequently drive descending pain facilitatory mechanisms to produce hypersensitivity and antinociceptive tolerance.Acute systemic morphine administration produced a potentiation of CCK release in the RVM as measured using microdialysis techniques. Sustained systemic morphine administration sufficient to produce thermal and tactile hypersensitivity resulted in a significant increase in basal CCK release in the RVM. Spinal nerve ligation (SNL) produces similar behavioral hypersensitivity. CCK levels in the RVM also increased following SNL. These findings suggest that endogenous CCK released in the RVM drives descending facilitatory pathways to produce hypersensitivity following sustained morphine administration and neuropathic pain.Disease states such as neuropathic pain offer special challenges in drug design due to system changes that accompany these diseases. Here, novel peptides with agonist binding affinity and bioactivity at δ and μ opioid receptors and simultaneous antagonist activity at CCK receptors have been developed. Using in vivo behavioral measures, it was shown that intrathecal (i.th.) administration of these compounds suppresses the thermal and tactile hypersensitivity caused by spinal nerve ligation (SNL).These studies support the hypothesis that endogenous CCK drives descending pain facilitatory pathways and that bi-functional compounds that act as opioid agonists and CCK antagonists are effective for the treatment of neuropathic pain.

by Julia Luen-wah Woo. / Thesis (M.Ph.) -- Chinese University of Hong Kong, 1988. / Bibliography: leaves 90-94.

Thesis (Ph. D.)--University of Hong Kong, 1987.

Thesis (Ph. D.)--University of Hong Kong, 1988.

Thesis (Ph. D.)--University of Hong Kong, 1970. / Typewritten.