p53 protein accumulation in addition to the transactivation activity is required for p53-dependent cell cycle arrest after treatment of cells with camptothecin.

In this study we characterize the connections between p53-dependent G1 cell cycle arrest, transcriptional activation of the protein and the increase of its intracellular steady-state concentration. Several cell lines expressing wild-type p53 protein were treated with increasing concentrations of DNA-damaging drug camptothecin. Lower doses of the drug caused transcriptional activation of p53, but no accumulation of the protein was detected. Only after a certain threshold dose of camptothecin does the amount of the protein rapidly increase and reach its plateau levels. The threshold dose was different for different cell lines, but the general non-linear profile was similar. Increase of p53 level was accompanied by additional transcriptional activation of some p53 target genes (i.e. waf1), but not the others (mdm2). We demonstrate here that transcriptional activation of p53 after the treatment of camptothecin is not sufficient to cause p53-dependent G1 cell cycle arrest. The latter is observable only after the increase of steady-state level of p53. Low drug concentrations, although accompanied by transcriptional activation of p53, do not cause either p53 protein accumulation nor cell cycle arrest at G1. We propose a model for p53 acting as a part of cellular sensor system detecting the severity of DNA damage.

Tumour associated mutants of p53 can inhibit transcriptional activity of p53 without heterooligomerization.

Tumour suppressor protein p53 is the most frequent target of mutations occurring in different types of human cancers. Most of these are point mutations clustered in certain 'hot spots'. Because p53 is a tetramer in solution, it can form heterooligomers when both wild-type and mutant forms of p53 are expressed in the same cell. Inactivation of wt p53 by heterooligomerization has been proposed as a mechanism for dominant negative effect of mutant protein. In this paper we show that other mechanisms can also be involved in the inhibition of transcriptional activity of wt p53 by mutant proteins. In addition to suppressing the wt p53 activity, mutant proteins are also able to suppress the activity of p53 protein unable to oligomerize. Either N- or C-terminus of mutant p53 are needed for this activity. The suppression of transcriptional activity described is restricted to p53-dependent promoters and no effect is seen with the promoter not containing p53 binding site. Point mutants also inhibit the growth suppressing activity of monomeric p53. Our data allow to propose the existence of a cofactor specifically needed for p53-dependent transcription. Depletion of this cofactor could be an alternative mechanism of inactivation of wt p53 by its point mutants.

Assessment of urinary incontinence.

1. In the past, nursing practice toward incontinence has focused on urine containment and skin protection rather than on proactive treatment-oriented therapeutic care. 2. Accurate assessment and diagnosis of urinary incontinence determine the success of treatment. 3. Efforts directed at early identification, appropriate assessment and treatment, and linkage to community agencies should be initiated by the nurse.

Developing a restraint use policy for acute care.

Restraint use has been a recent focus of attention in long-term care facilities. The Joint Commission on Accreditation of Healthcare Organizations, the Commission on Accreditation of Rehabilitation Facilities, and the Food and Drug Administration have devoted attention to the prudent use of restraints. The authors address efforts of an acute care facility to comply with these regulations.