DNA ploidy and nuclear morphometric variables for the evaluation of melanocytic tumors in dogs and cats.

OBJECTIVE: To determine the prognostic importance of the DNA content and nuclear morphometric variables in melanocytic tumors of cats and dogs. SAMPLE POPULATION: 27 melanocytic tumors of dogs and cats. PROCEDURES: Biopsy specimens were investigated by quantitative image analysis after the Feulgen staining method. The DNA content (index), nuclear diameter, ploidy balance, proliferation index, hyperploidy, and growth fraction (Ki67) were measured. Using 1-way ANOVA and a Pearson correlation test, the relationships between the different variables were tested. Their role in the prognosis in affected dogs and cats was estimated using the Cox regression test with respect to 6 months postoperative survival rate. RESULTS: Significant correlations were found between DNA index and ploidy balance and proliferation index. A significant correlation was also found between hyperploidy and DNA index, and between ploidy balance and proliferation index. Significant differences were found between histologically malignant and benign melanocytic tumors but not between primary malignant tumors and metastatic malignant tumors for DNA index and ploidy balance. No correlation was found between DNA variables and survival time. CONCLUSION AND CLINICAL RELEVANCE: In melanocytic tumors of cats and dogs, DNA index and ploidy balance can be used to differentiate histologically benign from malignant tumors. However, DNA content and nuclear morphometric variables have little value in predicting survival time. The DNA index and ploidy balance provide an additional tool to evaluate melanocytic tumors of cats and dogs. Survival in dogs and cats with melanocytic tumors, however, is not determined by modifications of DNA content or changes in nuclear morphometry of tumor cells.

Combined characterization of composite tabular silver halide microcrystals by cryo-EFTEM/EELS and cryo-STEM/EDX techniques.

The combination of cryo-energy filtering transmission electron microscopy (EFTEM)/electron spectroscopic diffraction (ESD)/electron energy-loss spectroscopy (EELS) and cryo-energy-dispersive X-ray (EDX) analysis in the scanning transmission (STEM) and scanning (SEM) modes was applied for the characterization of composite tabular Ag(Br,I) microcrystals. A low-loss fine structure in EEL spectra between 4 and 26 eV was attributed to excitons and plasmons possibly superimposed with interband transitions and many-electron effects. The contrast tuning under the energy-filtering in the low-loss region was used to image the crystal morphology, defect structure (random dislocations and ¿111¿ stacking faults) and bend and edge contours as well as electron excitations in the microcrystals. Sharp extra reflections at commensurate positions in between the main Bragg reflections and diffuse honeycomb contours in ESD patterns of the microcrystals taken near the [111] zone were assigned to the number of defects in the shell region parallel to the grain edges and polyhedral clusters of interstitial silver cations, respectively. The imaginary part of the energy-loss function, Im (-1/epsilon), and the real and imaginary parts, epsilon1 and epsilon2, of the dielectric permittivity were determined by means of a Kramers-Kronig analysis. An assignment of exciton peaks based on calculations of electronic band structure of silver bromide is proposed. Inner-shell excitation bands of silver halide were detected in line with EDX-analyses. The energy-loss near-edge structure (ELNES) of the AgM4,5-edge governed by spin-orbital splitting between the 3d3/2- and 3d5/2-states has been evaluated. Combined silver and halide distributions were obtained by a three-window method (EFTEM) and by EDX/STEM including area mapping and line profiling of iodide.