The undertreatment of pain: scientific, clinical, cultural, and philosophical factors.

This essay provides an explanation and interpretation of the undertreatment of pain by discussing some of the scientific, clinical, cultural, and philosophical aspects of this problem. One reason why pain continues to be a problem for medicine is that pain does not conform to the scientific approach to health and disease, a philosophy adopted by most health care professionals. Pain does not fit this philosophical perspective because (1) pain is subjective, not objective; (2) the causal basis of pain is often poorly understood; (3) pain is often regarded as a "mere" symptom, not as a disease; (4) there often are no "magic bullets" for pain; (5) pain does not fit the expert knowledge model. In order for health care professionals to do a better job of treating pain, some changes need to occur in medical philosophy, education, and practice.

Incorporation of rat brain adenylate cyclase into artificial phospholipid vesicles.

Adenylate cyclase was solubilized from rat brain particulate fraction with the nonionic detergent, Nonidet P-40. Incubation of detergent-solubilized adenylate cyclase with liposomes prepared from egg yolk phosphatidylcholine results in virtually quantitative incorporation of the enzyme activity into phospholipid vesicles. Incorporation of adenylate cyclase into liposomes results in an approximately 10- to 20-fold purification relative to the solubilized preparation giving a final specific activity of about 50 nmol of cAMP min-1 mg-1. The detergent-solubilized adenylate cyclase migrates as a broad band between 14 and 33% sucrose on density gradient centrifugation, separated from the endogenous phospholipid. Following overnight incubation of the solubilized enzyme with exogenous phospholipid, all enzyme activity is found in a narrow band between 7 and 9% sucrose, co-migrating with the phospholipid. The adenylate cyclase could not be released from the liposomes by extraction with high ionic strength, low ionic strength-EDTA, or sonication. Treatment of liposomal adenylates cyclase with soluble proteases or immobilized trypsin destroys enzyme activity. Thus, it is likely that a functionally important part of the enzyme molecule is exposed on the outer surface of the liposome. Optimal conditions for the incorporation of adenylate cyclase into liposomes, and some effects of manipulating the phospholipid composition on enzyme activity are reported.