The bioavailability of oral ketoconazole is reduced in patients with AIDS, largely as a result of gastric hypochlorhydria. Ketoconazole tablets should therefore be given with acid in these patients.

Purification was done by using starch gel electrophoresis for labeled gastrin (4) and by using adsorption to and elution from Quso G32 for labeled CCK (4). Radioimmunoassay. Radioimmunoassay was done with a 2.5-ml incubation volume. The standard diluent was generally 0.02 M barbital, pH 8.6, containing either 0.2 g of bovine serum albumin per 100 ml or 2% fetal bovine serum. The concentration of the labeled gastrin tracer and the labeled CCK tracer was generally <0.5 pg/ml and <10 pg/ml, respectively. The crossreactivities of PGI, intact CCK, and CCK-8 were studied with each of the antisera. Radioimmunoassay of extracts, starch-block eluates, and Sephadex fractions was performed by using methods quite similar to those established in our laboratory for other hormones (4, 5).Brain Extracts. Immediately after death, specimens for extraction were taken from various portions of the brain of the pig including the cortex, the cerebellum, and the pons. The tissues were sectioned while still frozen, 0.1 M HCI or distilled water was added to produce a concentration of 0.1 g wet weight of tissue per ml, the solutions were boiled for 3 min, and then the tissues were homogenized in their extraction solution by using a Teflon tissue grinder. The extracts were assayed directly with each antiserum and were also fractionated by starch block electrophoresis and on Sephadex columns using radioactive marker molecules to locate the positions of the void volume and the salt peak. These methods were similar to those described from our laboratory for the gastrin peptides (6, 7). RESULTSThe crossreactivities of PGI, CCK, CCK-8, and water and acid extracts of the pig cerebral cortex were studied with each of the antisera (Fig. 1). The brain extracts crossreacted strongly with the goat antiserum against porcine CCK which had good sensitivity for the detection of porcine CCK but low sensitivity for the detection of PGI and CCK-8; this extract also crossreacted strongly with the rabbit antiserum against G-(14-17)-which had good sensitivity for the detection of PGI and CCK-8 but much poorer sensitivity for the detection of intact CCK. These findings suggest that the brain extract contains both CCK-like and CCK-8-like peptides. No detectable immunoreactivity was observed for the pons or cerebellum extracts with either antiserum. The 0.1 M HC1 extract of the cortex appeared to contain 0.4 ,ug of CCK per g wet weight of tissue by using the goat anti-CCK serum and 0.03 ,ug of CCK-8 per g wet weight of tissue by using rabbit B antiserum. The boiling water extraction resulted in apparent concentrations of 0.2 ,ug of CCK per g wet weight of tissue and 0.2 ,ug of CCK-8 per g wet weight of tissue. Thus, 0.1 M HCl is more efficient for the extraction of the CCK-like peptide, but water is more efficient for the extraction of the CCK-8 like peptide from the brain.

No abstract

Immunoreactive intact cholecystokinin and its COOH-terminal octapeptide are found in brain as well as in extracts of gut of the monkey, dog, and pig, by using an antiserum with equivalent sensitivities for detecting the octapeptide in free form or incorporated in the intact molecule. The failure to detect intact cholecystokinin in extracts from monkey or dog by using an antiserum developed by immunization with porcine cholecystokinin is presume to be due to marked species differences in the NH2-terminal portion of the molecule. Tryptic digestion converted the intact cholecystokinin from all species to a peptide resembling the COOH-terminal octapeptide. The amount of cholecystokinin in the brain is comparable to that found in the gastrointestinal tract, the traditional site for this peptide.We have previously reported that a peptide resembling intact cholecystokinin (CCK) in size, charge, and immunologic specificity is found in extracts of the pig cerebral cortex (1). A peptide, first suggested to be gastrin-like (2) and later consid ered to resemble more closely the COOH-terminal octapeptide of CCK (CCK-8) (1,3,4), has been found in the brains of many animal species including not only mammals but also birds, fish, and amphibians (2). In this report we demonstrate that a CCK-like peptide is found in the brain as well as in the gut of the dog and monkey and that failure to detect it with an antiserum developed by immunization of a goat with porcine CCK (pCCK) is due to the marked species specificity of this antiserum which appears not to crossreact with CCK-8. Radioimmunoassay. 125I-Labeled synthetic human gastrin I and 125I-labeled CCK were prepared by our minor modification of the chloramine-T technique (5) using about 1.2 mCi of 125I (Amersham/Searle) for 1 ,tg of gastrin and 0.5 mCi of 125I for each 1 ,ug of CCK. Labeled gastrin was purified by starch gel electrophoresis and labeled CCK by adsorption to and elution from Quso G32 (5). MATERIALS AND METHODSThe production of the antisera used in this study has been described (1). One antiserum was prepared in a goat (goat 1) by immunization with pCCK. This antiserum does not crossreact with CCK-8 or heptadecapeptide gastrins at concentrations 1000-fold higher than the concentration of intact pCCK that decreases the ratio of antibody-bound to free labeled antigen to less than 10% of the ratio in the absence of unlabeled hormone. The other antiserum was prepared by immunization of a rabbit (rabbit B) with the COOH-terminal gastrin tetrapeptide amide. The antiserum used in the present study was obtained somewhat later in the course of immunization although from the same rabbit as reported previously (1). By using the later bleeding and '25I-labeled synthetic human gastrin as the tracer, the crossreactivities of pCCK and of CCK-8 were virtually identical on a molar basis. Heptadecapeptide gastrins reacted somewhat more strongly than the CCK peptides. Therefore, the gastrin content of all samples was also determined by using the guinea pig antiserum generally...