Synthesis and pharmacologic properties of 6-succinylcodeine.

In our search for a ligand to be used for affinity chromatography in the separation of putative, codeine-specific receptors, we have synthesized a pharmacologically active codeine derivative, 6-succinylcodeine (Ib). The structure of the compound has been confirmed. It is markedly less toxic than the parent compound, codeine (Ia), and has significantly weaker antitussive properties in the cat. On the other hand, its antinociceptive properties in the mouse and effects on guinea pig ileum are comparable to those of codeine. An interesting pharmacological property of Ib is its hypotensive effect in both cats and rhesus monkeys. The compound has been successfully coupled to an aminoalkyl agarose matrix. When coupled to the matrix, the drug loses its capacity to cause contraction of the guinea pig ileum but this property is restored upon alkaline hydrolysis of the coupled beads. Whether the diminished antitussive properties, as compared to the parent compound, or the loss of capacity to inhibit guinea pig ileum contractility when coupled to agarose would limit its usefulness for affinity chromatography of codeine-specific receptors is being investigated.

Induction of experimental myasthenia gravis in rhesus monkeys: a model for the study of the human disease.

Experimental autoimmune myasthenia gravis (EAMG) was induced in rhesus monkeys using purified acetylcholine receptor (AChR) from Torpedo california. A single dose of 80 micrograms induced antibody formation two weeks after injection. Two subsequent doses at two-week intervals caused clinical signs (anorexia, fatigability, weight loss, ptosis and dysphagia) which initially responded to treatment with neostigmine. Histologic examination of post-mortem tissues revealed lesions characteristic of myasthenia gravis in man: muscular atrophy, fibrous degeneration and lymphocytic infiltration. Antibodies were quantitated in the sera of three other monkeys which received only 60 micrograms of purified AChR. Abnormally high titers persisted for two years (60-200 micrograms /ml versus 0-10 micrograms/ml for controls). A monkey injected with 60 micrograms AChR as part of reconstituted membrane vesicles had lower titers (30-50 micrograms/ml) than those which received purified receptor. Only those monkeys with antibody titers exceeding 800 micrograms/ml developed overt disease. These titers were 4-100 times higher than those reported for myasthenic humans. The antibody-antigen molar ratios were higher for monkeys with disease than for asymptomatic animals. These data suggest that the diversity of antibody molecules synthesized by the sensitized monkeys determined the appearance of clinical signs, and that the cross reaction of anti-torpedo antibodies with monkey receptor was primarily responsible for the development of EAMG.

Binding of [3H]phenycyclidine to rat and human blood constituents.

The binding of [3H]phencyclidine (PCP) to rat serum and human plasma was studied using equilibrium dialysis. [3H]PCP bound with a relatively low affinity to both rat serum (KD = 1.5 X 10(-5) M) and human plasma (KD = 6.2 X 10(-6) M). However, the binding capacity was quite large for rat serum (5.7 nmoles/ml) and human plasma (5.6 nmoles/ml). Binding was readily reversible as shown by the efflux of [3H]PCP from a dialysis bag containing the rat serum-drug complex. In addition, the [3H]PCP-human serum complex appeared to dissociate completely when analyzed by Sephadex gel filtration chromatography. The low affinity of PCP for serum appeared to account in large part for the high tissue-to-plasma ratios that are observed in animals and humans injected with this drug. In vitro equilibration of [3H]PCP between rat serum and tissue homogenates resulted in at least a 10-fold accumulation of [3H]PCP in the homogenates. [3H]PCP was found to bind weakly to the major protein components of human serum (macroglobulins, immunoglobulins and albumins). The weak nature of the binding to serum proteins coupled with the relatively high capacity of binding probably account for the failure of other drugs to compete for PCP binding.

Induction of allergic neuritis in rhesus monkeys.

Experimental allergic neuritis (EAN) was induced in rhesus monkey (Macaca mulatta) following sensitization with rabbit nerve (PNS) myelin in complete Freund's adjuvant (CFA) or with bovine P2 protein complexed with phosphatidyl serine (P2-lipid) in CFA. The response of monkeys receiving PNS myelin in CFA differed from the previous studies where monkeys developed clinical signs of fatal EAN within 15-20 days following sensitization. The monkeys in this study (6) showed a much longer delay (40-114 days) before the appearance of severe clinical signs, and 4 of the 6 animals survived without further attack (1 year). Monkeys (4) injected with P2-lipid (2:1 ratio; w/w) developed severe clinical signs of EAN which was fetal in 3 cases. Peripheral lymphocytes from monkeys sensitized to the P2-lipid showed a much stronger mitogeneic response to P2 protein than those from the PNS myelin-sensitized monkeys. on quantitation of the circulating anti-P2 antibodies, the P2-sensitized monkeys generally had much titers than those sensitized with PNS myelin.

Cardiolipins are 'in vitro' inhibitors of rat brain (Na+ + K+)-dependent ATPases. A probable mechanism of action.

Cardiolipins were found to potentiate the 'in vitro' inhibitory activity of (-)-delta 9-tetrahydrocannabinol on (Na+ + K+)-dependent rat brain ATPases. The compounds were found to be powerful inhibitors by themselves. At optimal concentrations of cations (Na+, K+, Mg2+), the compounds were found to be noncompetitive inhibitors of ATP (Ki = 3.5 x 10(-6) M) and 'uncompetitive' inhibitors of Na+. From gas-liquid chromatographic analysis of the cardiolipin preparations it can be inferred that their effectiveness as inhibitors is related to the linoleic acid contents. The preliminary data presented here suggest that cardiolipins inhibit the Na+-dependent phosphorylation step in the hydrolysis of ATP. Based on the observations reported in this work, a hypothesis is presented suggesting that there may be a functional or evolutionary explanation for the paucity of cardiolipins in cell plasma membranes.