Ceruletide for schizophrenia: a double-blind study.

Ceruletide, an analog of cholecystokinin (CCK), has been reported to have neuroleptic-like activity in mice, and, in three open studies, to benefit schizophrenic patients. This study evaluated ceruletide in schizophrenia using a double-blind design. Subjects were 17 chronic schizophrenics with residual symptoms following stabilization with neuroleptics. Patients randomly received two injections, 1 week apart, of either ceruletide (0.6 microgram/kg im) or placebo, while continuing neuroleptics; this regimen was found helpful in earlier studies. Evaluation included ratings of 29 variables related to prognosis in schizophrenia (e.g., age, number of previous hospitalizations), regular BPRSs and SCL-90s, and psychiatrist, patient, and relative ratings of global improvement. Results showed few significant differences between ceruletide and placebo, with exceptions as likely to favor placebo as ceruletide. Among the patients on ceruletide, no predictors of benefit were found. Possible reasons for the negative results are discussed.

Action of ATP-dependent DNase from Hemophilus influenzae on cross-linked DNA molecules.

The ATP-dependent DNase from Hemophilus influenzae digests double-stranded linear DNA molecules exonucleolytically while hydrolyzing large amounts of ATP to ADP. Various cross-linked linear duplex DNA molecules are partially resistant to the exonuclease action. Vaccinia DNA, containing natural terminal cross-links (probably in the form of terminal single-stranded loops), is much more slowly degraded than comparable "open-ended" DNA molecules, and ATP is consumed at a proportionately lower rate. It is postulated that the vaccinia DNA molecules undergo slow terminal cleavage by the single strand specific endonuclease activity of the enzyme, and are then rapidly degraded by the double strand exonuclease activity. Phage T7 DNA, containing an average of 100 4',5'8-trimethylpsoralen cross-links/molecule at random internal sites, is digested only to the extent of 2 to 3%. However, ATP hydrolysis continues at a linear rate long after DNA digestion has ceased. A stable enzyme-DNA complex is formed as demonstrated by co-sedimentation of DNA and ATPase activity in sucrose gradients. The hypothesis is advanced that the enzyme digests exonucleolytically to the first cross-link at each end of the DNA molecules where further movement is prevented. The enzyme then remains bound at the cross-links and functions continuously as an ATPase.