Oncogenic somatic events in tissue-specific stem cells: a role in cancer recurrence?

Tissue-specific stem cells (TSSCs) are a very unique cell type, with critical and well-defined roles for the homeostasis of high turnover tissues (such as the blood and the skin). Emerging evidence suggests that TSSCs are implicated in malignancies, with several theories being proposed and tested, including many attempts to identify the cells of origin and studies deigned to understand how TSSCs participate in age-related increase in cancer risk. A currently unexplored possibility in this respect is the plausible theory that an oncogenic event that arises at a TSSC would promote tissue replenishment by cells containing these mutations, with progressive propagation of such mutated TSSCs in the niche. Therefore, the effect of a somatic oncogenic event in a single TSSC may have more important implications than previously anticipated, resulting in sustained and progressively higher cancer risk. This model could have important implications for tumor recurrence, since in some cases the underlying cause might be the development of a new tumor originated from daughter cells of the TSSC that suffered the first oncogenic hit, rather than proliferation of residual cancer cells. In this review, we present and discuss approaches for testing the proposed theory of tumorigenesis and cancer risk, as well as practical implications for biomedical research and clinical practice.

Antifungal susceptibility, exoenzyme production and cytotoxicity of novel oximes against Candida.

Novel oximes were synthesized, their in vitro antifungal activity against Candida was evaluated and their cytotoxicity was determined. The procedure used for the synthesis of the oximes is aligned with the current green chemistry trend; water is employed as the solvent in this reaction. The minimum inhibitory and minimum fungicidal concentrations of the oximes were evaluated using the CLSI M27-A3 method. The influence of these compounds on the inhibition of the production of hydrolytic enzymes, phospholipase and proteinase by Candida was also investigated. The compounds showed a good ability to inhibit phospholipase, with a 50 % reduction in most cases. However, the tested compounds did not affect proteinase. The current results showed a substantial reduction in the phospholipase production, which suggests that compounds of this class may interfere with host infection and disease progression. The oximes examined showed lower fungicidal activities than fluconazole but interfered significantly with the expression of phospholipase. Some of the oximes included in this study could be a suitable matrix for the development of novel antifungal compounds.

Delays in the diagnosis of pulmonary tuberculosis in Coahuila, Mexico.

OBJECTIVE: To determine diagnostic delay in pulmonary tuberculosis (PTB) cases and analyse associated factors. METHODS: New PTB cases were studied in Coahuila, Northern Mexico, between 2008 and 2009. We obtained census data and data on residential address, symptoms and diagnosis from the national patient database; sociodemographic variables were obtained during home visits. Bivariate analyses used the Kaplan-Meier method; multivariate analysis consisted of modelling survival. RESULTS: We studied 458 subjects (median age 48 years), who were predominantly males (56.1%); the median years of schooling was 6.0 years, 83.4% were urban residents, 50.3% were unemployed, and 87.7% suffered from food poverty. The median delay between the onset of symptoms and the first medical consultation was 53.5 days. Lack of formal education (P = 0.050) and living ≥5 km from a health unit (P = 0.034) were associated with longer delays and consequently with severe symptoms (cough ≥2 weeks, P = 0.001; chest pain, P = 0.032; malnutrition, P = 0.003). Mean health system delay (between first consultation and smear test result) was 18.5 days, and was significantly longer when the first consultation was with a private physician (P < 0.001) and when patient age was ≥46 years (P = 0.001). CONCLUSIONS: In Coahuila, lack of formal education, living ≥5 km from a health unit, first consultation with a private physician, and being aged ≥46 years contributed to delays in PTB diagnosis.

Odontoblast RNA stability in different temperature-based protocols for tooth storage.

AIM: To evaluate the effect of four tooth storage temperature-based methods on quality of RNA obtained from cells retrieved from human dental pulps and human pre-dentine. METHODOLOGY: RNA was isolated from dental pulp tissue and from cells retrieved by scraping the pre-dentine of freshly extracted human third molars (n = 15) using TRIzol(®) reagent. Teeth were randomly assigned to the following temperature conditions: immediate RNA isolation after tooth extraction, liquid nitrogen (24 h), -80 °C (24 h), 20 °C (24 h) and 4 °C (6 h). RNA integrity was checked by the density of 28S and 18S ribosomal RNA. RT-PCR was used to analyse the expression of odontoblast makers (DSPP, DMP1 and MEPE) and the housekeeping gene GAPDH. RESULTS: All experimental conditions evaluated preserved RNA integrity. The three odontoblastic markers were amplified from the pulp tissue and from the cells associated with pre-dentine. CONCLUSION: The four storage options allowed RNA isolation for RT-PCR analysis. These findings may facilitate the use of clinically derived human dental pulp and odontoblasts for endodontic research.

Comparative analysis of two colorimetric assays in dental pulp cell density.

AIM: To compare and contrast two colorimetric assays used for the measurement of proliferation using two dental pulp cell types: dental pulp stem cells (DPSC) and human dental pulp fibroblasts (HDPF). METHODOLOGY: Dental pulp stem cells or HDPF were seeded at 0.25×10(4) cells per well in 96-well plates. Cell proliferation was evaluated after 24-72h. At the end of the experimental period, the sulforhodamine B (SRB) assay or a water-soluble tetrazolium salt (WST-1) assay was performed. Optical densities were determined in a microplate reader (Genius; TECAN). Data were analysed by Student's t-test (comparison between cell types) and one-way anova followed by Tukey test (time-point intervals). Pearson' correlation tests were performed to compare the two assays for each cell line. RESULTS: Both assays showed that DPSC had higher proliferation rates than HDPF. A positive significant correlation between the two colorimetric assays tested for both cell types DPSC (Pearson's correlation coefficient=0.847; P<0.05) and HDPF (Pearson's correlation coefficient=0.775; P<0.05). CONCLUSION: Both tests demonstrated similar trends of cell proliferation, and thus are both appropriate for the evaluation of DPSC and HDPF. The choice of assay is therefore one of the practical applications. SRB stained plates can be dried and stored so may have utility in laboratories where data may require review or when access to analytical equipment is limited. WST-1 assays have the benefit of both ease and speed and may have utility in laboratories requiring either high throughput or rapid analyses.

[Years of life lost by mortality: a component of the burden of disease]. / Anos de vida perdidos por mortalidade: um dos componentes da carga de doenças.

INTRODUCTION: The register of death by cause, sex and age groups of residents in 1994 in Rio Grande do Sul (RS) and Santa Catarina (SC), two Brazilian southern states, were studied to calculate the years of life lost (YLL), one of the two components that summarize disability adjusted life years (DALY), in RS, SC and Brazil. METHODS: The methodology employed is the same used in the Global Burden of Disease study to quantify the mortality component (YLL) of DALY in the world. RESULTS: The results show that the greatest proportion and rates caused by Group II (Noncommunicable diseases), linked with more advanced stages of the epidemiological transition, in RS, SC and Brazil. But in both states and especially in Brazil, Group I (Communicable, maternal, perinatal and nutritional conditions) causes an important proportion of YLL. The Group III (Injuries) was the second more important group in RS and SC and the third in Brazil. Road traffic accidents are particularly important in SC, where the intentional injury rate is half than the one in RS. The leading causes of YLL were road traffic accidents, ischemic heart disease and cerebrovascular disease in SC, and ischemic heart disease, cerebrovascular disease and road traffic accidents in RS. CONCLUSIONS: Death certification in the southern region of Brazil has a complete coverage and miscoded death proportion is small, providing a reliable mortality information. DALY allow comparing fatal and nonfatal health outcomes to determine the importance of different diseases and to establish health priorities. DALY are also an useful tool to identify disadvantaged groups, target health interventions and provide information for social control of resource allocation.