Electrophoretic transfer of proteins across polyacrylamide membranes.

The electrophoretic transfer of purified proteins has been examined in a Gradiflow "Babyflow BF100" unit. A number of factors affect protein separation within this preparative electrophoresis system. We established that the rate of protein transfer was proportional to the applied voltage. The transfer is slowest at the isoelectric point (pI) and increased the further away the pH was from the pI of the protein. Protein transfer was found to be independent of the ionic strength of the buffer, for buffers that excluded the addition of strong acids or strong bases or sodium chloride. Transfer decreased as the pore size of the membrane decreased. Finally, transfer was inhibited at high salt concentrations in the protein solution, but remained unaffected when urea and non-ionic detergents were added to the solution. To increase the speed of protein separations, buffers with low conductivity should be used. A pH for the optimal separation should be selected on the basis of the relative pI and size of the target proteins and that of the major contaminants.

A comparison of uterine cervical cytology and biopsy results: indications and outcomes for colposcopy.

BACKGROUND: There is some debate in the literature over the proper approach to the patient with a mildly abnormal cervical cytologic finding. One current approach for handling low-grade cytologic abnormalities is to perform colposcopy and biopsy if atypia, human papillomavirus (HPV) changes, or mild dysplasia is noted on cytologic examination. If a Papanicolaou (Pap) smear shows inflammation without atypia, the test is repeated after 3 months, and if inflammation does not clear, colposcopy is performed. This study was undertaken to determine whether the above recommendations are appropriate. METHODS: In a 1-year period, 125 patients underwent colposcopy and biopsy. Results were reviewed and compared. RESULTS: Of 47 patients with smears showing human papillomavirus (HPV) changes, 68% had a higher grade abnormality (dysplasia) on biopsy; 15% had moderate or severe dysplasia. Of eight patients with atypia, 63% had dysplasia on biopsy. Of 41 patients with mild dysplasia on Pap smear, 37% had moderate dysplasia or higher grade disease on biopsy. Of nine patients with persistent inflammation on cytologic examination, biopsy showed 56% with inflammation, 33% with mild dysplasia, and 11% normal. CONCLUSIONS: Patients who presented with minimal Pap smear abnormalities such as HPV changes or atypia are likely to have a worse histologic diagnosis, with approximately two thirds showing dysplasia. Patients with persistent inflammation are less likely to have dysplasia. The results support our aggressive approach toward minimally abnormal smears and our consideration of inflammation without atypia as a separate and lower risk category.