Differentiation of mucinous from non-mucinous pancreatic cyst fluid using dual-stained, 1 dimensional polyacrylamide gel electrophoresis.

BACKGROUND: Pancreatic cysts are being increasingly identified in patients. Mucinous cysts have malignant potential whereas non-mucinous cysts do not. Distinguishing potentially malignant cysts from harmless ones by the characterization of cyst fluid contents remains a difficult problem. This study was undertaken to determine whether cyst fluid mucin glycoprotein analysis could differentiate mucinous from non-mucinous pancreatic cysts. METHODS: Cyst fluid from 28 patients who underwent resection of a pancreatic cyst was used for the study. In each case the type of cyst was histologically identified. One dimensional SDS polyacrylamide gel electrophoresis (1D-SDS PAGE) was performed on cyst fluid samples. For the detection of the separated proteins, we employed a novel dual staining technique. The gel was first stained with periodic acid Schiff (PAS), a mucin histochemical stain followed by a secondary protein staining with Simply Blue Safestain (Invitrogen). RESULTS: Visual scoring (based on the presence of mucins) gave a sensitivity of 95%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 88% for prediction of mucinous histology. CONCLUSIONS: One dimensional SDS polyacrylamide gel electrophoresis of pancreatic cyst fluid, followed by mucin (PAS) and protein (Simply Blue Safestain) staining, provides a means of concentrating and visualizing mucins, which allows the accurate differentiation of mucinous from non-mucinous histology in pancreatic cysts.

A 9,000-year record of Chagas' disease.

Tissue specimens from 283 principally spontaneously (naturally) desiccated human mummies from coastal and low valley sites in northern Chile and southern Peru were tested with a DNA probe directed at a kinetoplast DNA segment of Trypanosoma cruzi. The time interval spanned by the eleven major cultural groups represented in the sample ranged from approximately 9,000 years B.P. (7050 B.C.) to approximately the time of the Spanish conquest, approximately 450 B.P. ( approximately 1500 A.D.). Forty-one percent of the tissue extracts, amplified by the PCR reacted positively (i.e., hybridized) with the probe. Prevalence patterns demonstrated no statistically significant differences among the individual cultural groups, nor among subgroups compared on the basis of age, sex, or weight of specimen tested. These results suggest that the sylvatic (animal-infected) cycle of Chagas' disease was probably well established at the time that the earliest humans (members of the Chinchorro culture) first peopled this segment of the Andean coast and inadvertently joined the many other mammal species acting as hosts for this parasite.