Phenotype of FAECB (Facility for Automated Experiments in Cell Biology) Chinese hamster ovary mutants with minimal UV-sensitivity.

The Facility for Automated Experiments in Cell Biology (FAECB) collection of over 200 lines of ultraviolet (UV)-sensitive mutant Chinese hamster ovary (CHO) cells has previously been studied for complementation group assignment (CG), with representatives of rodent UV CGs 1-6 (ERCC1-6) and the new rodent XRCC9/FANCG group identified. Ten mutants from the collection, including a further six derived from wildtype AA8, three UV-sensitive double-mutants of CHO ERCC1 cell line UV4, and a UV-sensitive mutant of CHO XRCC1 cell line EM9, had not been assigned or characterized in these previous studies. These 10 mutants include 8 with approximately 1.5-fold the UV-sensitivity of the parental line (AA8, EM9, or UV4), and 2 with about 2-fold the UV-sensitivity of AA8. The present study reports the partial characterization of these 10 mutants in terms of sensitivity to UV (with and without caffeine), ionizing radiation, mitomycin C (MMC) and ethyl methanesulfonate (EMS); proficiency in DNA repair (unscheduled DNA synthesis (UDS)); and UV-mutability. The phenotypes of the 10 cell lines were heterogeneous, a number showed reduced UDS or UV-sensitization by caffeine, whilst others showed marked sensitivity to EMS or MMC, and they may have mutations in different genes involved in nucleotide excision repair, post-replicational repair, base excision repair or recombinational repair. Previous mutants isolated as part of the FAECB collection have proved to be extremely important in characterizing mammalian DNA repair processes and cloning human repair genes and these current mutants, whilst not as hypersensitive to UV, may still have the potential to make further contributions.

Therapeutic management of sexual abuse allegations in custody and visitation disputes.

Our experience is that in many cases, trying to assess the "truthfulness" or "falseness" of sexual abuse allegations that occur in the midst of custody and access disputes may not be possible. Instead therapeutic management of such cases is advocated. A case is presented in which sexual abuse was suspected because the recanting child displayed sexualized symptoms. Following a thorough assessment, which indicated that the child was abused, but could not confirm who the offender was, both the child and the mother were seen in psychotherapy on a regular basis. The father used counselling to achieve rights for visitations. The building of a therapeutic relationship allowed us to experiment with the situation to where we felt we could identify the potential offender who had to be kept away from the child. In addition, the therapeutic relationship enables this family to come to us to resolve their disputes rather than use the judicial system.

The challenge of sexual abuse: protection and therapy in a child welfare setting.

Toronto's SATP (Sexual Abuse Treatment Project), the first sexual abuse treatment program in a child welfare setting in Canada, provides comprehensive treatment resources for sexually abused children, their families, and offenders. The authors include a description of the program's major components, as well as an evaluation of SATP's first eighteen months.

Ionic diffusion in transverse tubules of cardiac ventricular myocytes.

We have estimated the rate of diffusion of calcium ions in the transverse tubules of isolated cardiocytes by recording changes in peak calcium current (ICa) caused by rapid changes of the extracellular calcium concentration ([Ca]o) at various intervals just preceding activation of ICa. Isolated ventricular cells of guinea pig heart and atrial cells from rabbit heart were voltage-clamped (whole cell patch), superfused at a high flow rate, and stimulated continuously with depolarizing pulses (0.5 Hz, 200- or 20-ms pulses from a holding potential of -45 or -75 mV to 0 mV). In ventricular cells, the change in peak ICa following a sudden change of [Ca]o increased rapidly as the delay between the solution change and depolarization was increased, up to a delay of approximately 75 ms [time constant (tau) approximately 20 ms, 30-40% of total current change), and then increased more slowly (tau approximately 200 ms, 60-70% of total current change); 400-500 ms were needed to achieve 90% of the total current increase. In atrial cells, a clear separation into two phases was not possible and 90% of the current change occurred within 85 ms. The slow phase of current change, which was unique to the ventricular cells, presumably reflects the slow equilibration of ions between the bulk perfusate and the lumina of the transverse tubules. If the lengths of the transverse tubules were equal to the cell thickness, the slow rate of change of current would be consistent with an apparent diffusion coefficient for calcium ions of 0.95 x 10(-6) cm2/s, considerably smaller than the value in bulk solution (7.9 x 10(-6) cm2/s). Most likely, this discrepancy is due to a high degree of tortuosity in the transverse tubular system in guinea pig ventricular cells or possibly to ion binding sites within the tubular membranes and glycocalyx.