The human papillomavirus (HPV)-6 and HPV-16 E5 proteins co-operate with HPV-16 E7 in the transformation of primary rodent cells.

E5 is the smallest transforming protein encoded by the human papillomaviruses (HPVs). It has been shown to promote anchorage-independent growth in established NIH 3T3 cells, an activity that is enhanced in the presence of epidermal growth factor (EGF). It is thought that this activity of E5 is brought about by an increase in the half-life of stimulated EGF receptors, possibly through the perturbation of receptor processing. Recent studies have also shown that E5 can co-operate with HPV-16 E7 to stimulate proliferation of primary rodent cells. Using haemagglutinin I epitope-tagged E5 proteins, we have compared the mitogenic activity of HPV-6 and HPV-16 E5. Both tagged proteins retain the ability to bind to the cellular 16 kDa H(+)-ATPase protein. In addition, both HPV-6 and HPV-16 E5 retain the ability to co-operate with E7 in primary rodent cells, although HPV-16 E5 is considerably more active than HPV-6 E5 in these mitogenic assays. Interestingly, transfection of a plasmid over-expressing c-Raf appears to be capable of functionally substituting for E5 in the co-mitogen assays. Polyclonal cell lines derived from baby rat kidney cells co-transfected with E7 and E5 genes continue to express both the E5 and E7 mRNA, although the level of E5 expression is very low and protein cannot be detected. These polyclonal lines appear to be immortal and in some cases demonstrate anchorage-independent growth, an activity which is enhanced by the addition of EGF.

Influence of bony resorption on endodontic treatment.

A review of prognosis studies has examined success rates between samples of teeth, both with and without radiolucent lesions, treated conventionally. The presence of a lesion predisposes the endodontic case to a lower success rate. On the basis of experimental data on the use of calcium hydroxide, investigation of increasing success with placement of calcium hydroxide in the canals of teeth with periapical lesions for 3 to 10 months prior to conventional filling is proposed.

Pain: a poor parameter of evaluation in dentistry.

In summary, we must be aware of the limitations of our instruments for determining success. A diagnosis is achieved by developing a composite picture through a keen gathering of all factors leading to the disease. Pain must surely be considered in patient management and patient-dentist rapport, but to allow our judgment to be swayed by pain alone is no more rational than to hinge our diagnosis upon a single other test. It is of paramount importance that we realize that, pulpally, periodontally, and periapically, there is no correlation between amount of destruction and reported presence or absence of pain. Pain is a poor parameter of evaluation.