Search

A technique is presented for establishing the presence of kinetochores in micronuclei (mn) using CREST antikinetochore antibodies and immunofluorescence. In cultured lymphocytes blocked in their second cycle by cytochalasin-B 61% baseline mn possess kinetochores, and thus originated from whole chromosomes. Mn-inducing agents with different modes of action were compared to determine the proportion of mn with kinetochores: virtually all X-ray- and mitomycin-C-induced mn were derived from acentric fragments as shown by the absence of kinetochore immunofluorescence, whereas the majority (79%) of colcemid-induced mn were CREST positive, reflecting the formation of mn through failure of attachment of chromosomes to the spindle. The proportion of mn without kinetochore fluorescence in the control (39%) and colcemid-treated (21%) cultures was greater than expected and possible reasons for this are discussed.

The induction of sister chromatid exchange (SCE) by opium pipe scrapings (sukhteh, Su) and the pyrolysis products of opium (Op) and of its major alkaloids, morphine (Mo), have been compared with that of cigarette smoke condensate (CSC). All pyrolysates induced SCE and the frequency was further increased by the inclusion of S9-mix in the protocol. The pyrolysates of Op induced considerably more SCE than CSC when the same concentrations were compared on a weight basis, and the rank in order of potency in CHO cells was MO greater than Op greater than CSC greater than Su. The Op pyrolysates may therefore contribute a significant risk factor to the observed high incidence of oesophageal cancer in areas of Iran where heavy Op usage occurs.

This paper describes a fast and accurate method for the identification of autoradiographically labelled human hypoxanthine-guanine phosphoribosyl transferase (HGPRT) variant lymphocytes on slide preparations using a high-speed computer image analysis system--the Fast Interval Processor (FIP). The system has been developed primarily for the analysis of cultured human peripheral blood lymphocyte populations in which the frequency of labelled cells may vary from less than one to more than 2,000 in every 10,000 cells. Evaluation experiments have demonstrated the excellent performance of FIP in the counting of labelled and total cells over this frequency range.