A possible explanation for the variable frequencies of cancer stem cells in tumors.

A controversy surrounds the frequency of cancer stem cells (CSCs) in solid tumors. Initial studies indicated that these cells had a frequency ranging from 0.0001 to 0.1% of the total cells. Recent studies have shown that this does not always seem to be the case. Some of these studies have indicated a frequency of [Formula: see text]. In this paper we propose a stochastic model that is able to capture this potential variability in the frequency of CSCs among the various type of tumors. Considerations regarding the heterogeneity of the tumor cells and its consequences are included. Possible effects on conventional treatments in clinical practice are also described. The model results suggest that traditional attempts to combat cancer cells with rapid cycling can be very stimulating for the cancer stem cell populations.

The noise and the KISS in the cancer stem cells niche.

There is a persistent controversy regarding the frequency of cancer stem cells (CSCs) in solid tumors. Initial studies indicated that these cells had a frequency ranging from 0.0001% to 0.1% of total cells. Recent studies have shown that this does not seem to be always the case. Some of these studies have indicated a frequency of 40%. Through a simple population dynamics model, we studied the effects of stochastic noise and cellular plasticity in the minimal path size of a cancer stem cells population, similar to what is done in what is sometimes called the Kierstead-Skellam-Slobodkin (KISS) Size analysis. We show that the possibility of large variations in the results obtained in the experiments may be a consequence of the different conditions under which the different experiments are submitted, specifically regarding the effective cell niche size where stem cells are transplanted. We also show the possibility of a noise induced transition where the stationary probability distribution of the CSC population can present bimodality.

Primary syphilis of oral mucosa: case report of an unusual manifestation.

Dental clinicians and other health care providers have long been concerned about a variety of infectious agents that may be transmitted within the dental setting. Many infectious diseases, including human immunodeficiency virus, hepatitis, tuberculosis, and syphilis are important both because of their potential transmissibility and because the first manifestations of the disease may appear in the oral cavity. Oral disease as a consequence of primary syphilis is rare. This article details a patient presenting with a labial nodule as her only clinical manifestation of undiagnosed primary syphilis.