Quantitative FISH by image cytometry for the detection of chromosome 1 imbalances in breast cancer: a novel approach analyzing chromosome rearrangements within interphase nuclei

Interphase cytogenetics have become a widespread tool for investigation of chromosome rearrangements in solid tumors. The most recurrent chromosome alteration within breast cancer affects chromosome 1, leading principally to gain of the long arm and/or loss of the short arm. We have developed a new method for detection of chromosome 1 arm imbalances in interphase nuclei. The method is based on quantitation of the fluorescence signals emitted by the hybridized two-color paintings of the short and long arms using image cytometry. The chromosome arm imbalance was determined by calculating the ratio of both fluorescence emissions of each arm. The ratio of the paintings of normal lymphocytes was used as a reference. Three breast cancer cell lines, 13 fresh tumor samples, and 6 fine-needle samplings of breast cancer were analyzed using an automated image cytometer. Whenever possible, classic cytogenetics and in situ hybridization on metaphases were performed as controls. Fluorescence ratios representing the imbalances of chromosome 1 arms with values between 1 and 3.2 were measured. Data between classic cytogenetics and interphase cytogenetics were well-correlated (r = 0.89). This method, which enables an easy detection of intrachromosomal imbalances without need of metaphase preparations, detects malignant cells and can be extended to other carcinomas for which chromosome 1 arm imbalances are recurrent or chromosome alterations specific of other malignancies. In comparison to other interphase fluorescence in situ hybridization techniques, it avoids every spot scoring problem encountered when using centromeric probes and the difficulties in interpreting structural rearrangements.     

Effects of temperature on norepinephrine-induced sinus acceleration and overdrive suppression in the isolated dog atrium

Using an isolated, blood-perfused atrium preparation, the effects of temperature on SA nodal pacemaker activity were investigated in 9 preparations. The PP interval decreased as temperature was raised. Regular sinus rhythm and atrial contraction were maintained above approximately 26 degrees C. Below 26 degrees C, sinus depolarization still showed a regular rate, although atrial contractions had ceased. At about 24 degrees C, atrial rhythm became irregular. Below 20 degrees C, atrial depolarization disappeared. Chronotropic responses to norepinephrine were suppressed at decreased temperatures, not only with respect to maximum PP shortening but also to the threshold dose for inducing sinus acceleration. Overdrive suppression was not influenced significantly by decreasing temperature. These results indicate that a temperature decrease causes suppression of SA nodal pacemaker activity, although the SA node continues to function regularly until about 25 degrees C.