At least two distinct epigenetic mechanisms are correlated with high-frequency “switching” for aprt phenotypic expression in mouse embryonal carcinoma stem cells

A series of clones displaying high frequency switching phenotypes for expression of the adenine phosphoribosyltransferase (aprt) gene were previously isolated from the P19 mouse embryonal carcinoma stem cell line. Most clones contained only oneaprt allele. We report here the characterization of each of these clones with regards to enzymatic activity, mRNA steady state levels, DNA methylation, and chromatin conformation. When clones were selected for resistance to the purine analog 2,6-diaminopurine, which requires markedly reduced levels of APRT enzymatic activity, two distinct classes were observed. The first class was associated with reduced or undetectable levels ofaprt mRNA, hypermethylation of the 5 CpG island, and a closed chromatin conformation within this region. When clones of this class were selected for reacquisition of APRT enzymatic activity they were found to have increased mRNA levels, a hypomethylated CpG island, and an open chromatin conformation. In contrast, the second class of clones displayed wild-type levels of mRNA, CpG island hypomethylation, and an open chromatin conformation regardless of whether they were selected for the presence or absence of APRT enzymatic activity. The implications of these results for general mechanisms of epigenetic change in somatic cells and the possibility that expression of the mouseaprt gene may be developmentally regulated are discussed.     

Pancreatobiliary adenosquamous carcinoma (report of two cases)

Adenosquamous carcinomas are rare malignant tumors of the pancreas and periampullary region. We present two cases of pancreatic and periampullary adenosquamous carcinoma with clinicopathologic, histo- and immunohistochemical findings. A 51-year-old and a 48-year-old man presented with right upper quadrant pain of three months duration and jaundice for two weeks. Both cases had an elevation of liver enzymes and CA 19-9. In the first case, computerized tomography showed a 3 cm-mass at the pancreatic head. In the second one, endoscopic retrograde choledocopancreatography (ERCP) revealed a mass at the ampulla Vateri localization. A pancreatoduodenectomy was performed for both cases. Gross pathologic examination displayed a solid, gray-white colored 4 cm-tumor at the pancreatic head and a solid, pink-white colored, 2 cm-tumor at the periampullary region bulging into the duodenal lumen. Microscopically, both tumors were composed of solid nests of squamous cells with pearl formation and mucin-containing glandular cells and diagnoses were adenosquamous carcinoma. Furthermore, histo- and immunohistochemical findings were consistent with microscopic diagnoses.     

A solid-phase competition ELISA for measuring antibody to foot-and-mouth disease virus

A solid-phase competition ELISA has been developed to measure antibodies to foot-and-mouth disease (FMD) virus and has been validated using an extensive range of sera from cattle. The assay uses polyclonal antisera and inactivated purified 146S antigens of FMD virus and was compared with the liquid-phase blocking ELISA and the virus neutralisation test on a range of serum sets. When examining test sera at a 1:5 dilution with a cut-off point of 30% inhibition of reaction, the solid-phase competition ELISA was as sensitive as the liquid-phase blocking ELISA for sera from infected or vaccinated animals. The limit of detection of the solid-phase ELISA was similar to that of the liquid-phase assay and both tests had lower limit of detection (i.e. were able to detect lower amounts of antibody) than the virus neutralisation test. The specificity of the solid-phase ELISA was considerably higher than that of the liquid-phase blocking ELISA and almost equivalent to that of the virus neutralisation test. The assay thus retains the sensitivity of the liquid-phase blocking ELISA whilst being easier to use, more robust and specific, and therefore offers an improvement for FMD virus antibody detection.     

Measuring and understanding public awareness of fetal alcohol spectrum disorders in Alberta,Canada

Journal of Public Health - Efforts to increase public awareness about fetal alcohol spectrum disorders (FASD) sometimes fail to translate into direct changes in attitudes or behaviors regarding...     

The prognostic significance of total lymph node number in patients with axillary lymph node-negative breast cancer.

AIM: In node-negative breast cancer patients, several factors for survival have been evaluated and currently, some of them are accepted for their prognostic and/or predictive values after validation in the separate data sets. The prognostic significance of increases in the number of pathologically detectable axillary lymph nodes in the node-negative patients could not been established clearly. To address this question, we have reviewed our patients' records. METHODS: A retrospective cohort study was conducted in pathologically node-negative patients who underwent modified radical mastectomy for stage I and II breast cancer. Survival and multivariate prognostic factor analyses were carried out to determine whether the number of tumour-free lymph nodes in complete axillary dissection material in addition to known factors was significant for the outcomes. RESULTS: Two hundred and seventy consecutive patients were eligible to enter the trial. The median observation time and the median number of tumour-free lymph nodes were 61 (from 30 to 120) months and 18 (from 10 to 44), respectively. The cohort was divided into the groups according to the number of nodes. The 5-year event-free and overall survivals were 92.5 and 98.3% for patients who had 18 lymph nodes or less, and 70 and 86.7% for those who had more than 18 negative nodes, respectively (P < 0.00001). Multivariate analysis for event-free survival demonstrated that the number of lymph nodes (Relative risk: 3.2 and 95% confidence interval: 1.7 to 5.9) in addition to the pathological tumour size and age was the most important independent prognosticator. In similar, multivariate analysis for overall survival showed that the number of lymph nodes together with the tumour size was the significant indicator (RR of cancer-specific dying in patients who had more than 18 nodes: 3.1 and 95% CI: 1.2 to 8.5). CONCLUSION: The increases in number of tumour-free lymph nodes are clinically important and this parameter should be taken into consideration in the breast cancer patients without metastatic lymph nodes.