Prolonged tamoxifen exposure selects a breast cancer cell clone that is stable in vitro and in vivo

The effects of long-term tamoxifen exposure on cell growth and cell cycle kinetics were compared between oestrogen receptor (ER)-positive (MCF-7) and ER-negative (MDA-MB-231) cell lines. In the MCF-7 cell line, prolonged tamoxifen exposure (0.5 mumol/l for > 100 days) blocked cells in G0-G1 of the cell cycle, and slowed the doubling time of cells from 30 to 59 h. These effects corresponded to an increase in the cellular accumulation of tamoxifen over time [mean area under concentration curve (AUC) = 77.92 mumoles/10(6)/cells/day]. In contrast, in the MDA-MB-231 cell line, long-term tamoxifen exposure had no obvious effect on the doubling time, and reduced cellular tamoxifen accumulation (mean AUC = 50.50 mumoles/10(6)/cells/day) compared to the MCF-7 cells. Flow cytometric analysis of MDA-MB-231 cells demonstrated that a new tetraploid clone emerged following 56 days of tamoxifen exposure. Inoculation of the MDA-MB-231 tetraploid clone and MDA-MB-231 wildtype cells into the opposite flanks of athymic nude mice resulted in the rapid growth of tetraploid tumours. The tetraploid tumours maintained their ploidy following tamoxifen treatment for nine consecutive serial transplantations. Histological examination of the fifth transplant generation xenografts revealed that the tetraploid tumour had a 25-30 times greater mass, area of haemorrhage and necrosis, a slightly higher mitotic index and was more anaplastic than the control neoplasm. The control wildtype MDA-MB-231 tumours maintained a stable ploidy following tamoxifen treatment until the eighth and ninth transplantation, when a tetraploid population appeared, suggesting that tamoxifen treatment may select for this clone in vivo. These studies suggest that prolonged tamoxifen exposure may select for new, stable, fast growing cell clones in vitro as well as in vivo.     

Percutaneous transhepatic drainage of the nondilated biliary system

Although reticulocyte counts can be reliably performed for up to 48 h after storage in EDTA, it is unclear whether this is applicable to the pediatric age group. In order to evaluate this, manual reticulocyte counts were performed on 20 specimens from pediatric patients stored at 4 degrees C for up to 24 h post collection. Samples were evaluated at 1-3, 6, 12, 18, and 24 h after storage in EDTA vacutainer tubes at 4 degrees C. The age of the subjects ranged from 1 day to 9 years with a median age of 3 years. Patients' reticulocyte counts ranged from 0 to 27% (5.89 +/- 7.21). No clinically significant changes were evident in the reticulocyte count over 24 h after specimen collection. The mean of the 20 specimens at 1-3 h was 5.50 and at 24 h was 5.40 (P > .05). The standard deviation of the mean values ranged from 7.03 to 7.26 (P > .05). The results indicate that reticulocyte counts may be performed on previously drawn blood held at 4 degrees C for up to 24 h post collection in a pediatric population without significant difference from baseline values.     

Structure and gene expression of avian cyclin D2

Avian cyclin D2 (Cyl D2)-encoding cDNA clones were isolated from a chicken UG9 T-cell lambda gt10 library. Sequence analysis revealed a high degree of sequence conservation with both the mouse and human Cyl D2, and somewhat lower similarity with the mouse and human Cyl D1 and D3. The homology is highest between species in the Cyl-box domain which is well conserved among human, mouse and chicken. A single 6.0-kb CYL2 mRNA is produced in both avian B- and T-cells, as expected.     

Improving the precision of measurements through application of chebyshev polynomials

It is shown that construction of the calibration characteristics of measuring devices may be reduced to expansion of these characteristics into Chebyshev polynomials. The coefficients of these polynomials (i.e., the parameters of the calibration characteristics) are determined by means of spectrum analyzers as the coefficients of the expansion into a Fourier series of the output signal of the device that arise when cosine signals arrive at the device 's input.Translated from Izmeritel'naya Tekhnika, No. 8, pp. 19–20, August, 1995.     

Effect of brief thermal pulses on intensity of heat liberation in helium boiling

Results are offered from a study of heat liberation in boiling of liquid helium upon a heated wall under impulsive thermal action conditions.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 3, pp. 373–376, September, 1987.     

Materials with a polymeric bitumen adhesive layer

The materials based on polyethylene and poly(vinylchloride) inner tapes and polymeric bitumen mastic with the trade mark TRANSKOR used for the anticorrosion protection of steel underground pipelines are described. For the capital repair of oil pipelines, a special construction solution is offered. This structure is composed of a polymeric bitumen primer, polymeric bitumen mastic, and heat-shrinkable film.     

Design for concurrent error detection and testability instorage/logic arrays

Storage/Logic Arrays (SLA's) represent a structured logic array approach to the design of VLSI sequential logic. Design for concurrent error detection and testability is complicated in these arrays by the presence of embedded memory elements and multiple levels of logic. A means of designing SLA's for ease of testability and concurrent error detection (CED) is provided in this paper. Test sets for static and dynamic CMOS circuits are described. Fault and error coverage is presented and performance and area costs are analyzed for example circuits. In addition, a means of implementing dynamic CMOS SLA's is presented and shown superior to previous NMOS, static CMOS, and dynamic CMOS approaches based upon power consumption and simplicity of design