Influence of blood sampling methods on dopamine-receptor-blocking activities as determined by a radioreceptor assay.

The influence of blood collection methods on dopamine-receptor-blocking activities as determined by a radioreceptor assay kit was investigated. Thirty-one patients treated with one of six neuroleptic drugs (thioridazine, trifluoperazine, haloperidol, chlorpromazine, thiothixene, or fluphenazine) participated in this study. Blood samples were drawn from each patient into five different evacuated blood collection tubes made by the same manufacturer (red-stoppered tube containing no additives, lavender-stoppered tube containing EDTA, green-stoppered tube containing heparin, dark blue-stoppered tube containing no additives, and dark blue-stoppered tube containing heparin). The results show that for five drugs (chlorpromazine, fluphenazine, haloperidol, thiothixene, and trifluoperazine), the dark blue-stoppered tubes without additives resulted in significantly higher dopamine-receptor-blocking activities than the red-, lavender-, or green-stoppered tubes. For thioridazine, the green-stoppered tubes resulted in significantly higher blocking activities than the blue- and red-stoppered tubes. The possible effect of tris(2-butoxyethyl) phosphate, a plasticizer, on dopamine-receptor-blocking activities by neuroleptic drugs is discussed.

A DNA nicking-closing enzyme encapsidated in vaccinia virus: partial purification and properties.

Vaccinia virus cores contain an activity which is able to relax both left-and right-handed superhelical DNA. This virus-specific nicking closing enzyme has been highly purified and differs from the corresponding host enzyme in salt optimum, in sedimentation coefficient, and in polypeptide composition as determined on sodium dodecyl sulfate/polyacrylamide gels. The enzyme is probably newly synthesized after the cessation of host protein synthesis which follows virus infection. The most highly purified preparation contains two polypeptides, one of molecular weight 24,000 and the other 35,000. The former polypeptide is a major constituent of the virus (7% of total protein by weight), whereas the latter is present in a much smaller amount (0.2%). Chromatography with denatured DNA-cellulose reveals that the activity is predominately associated with those fractions enriched in the polypeptide of greater molecular weight.