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Chromosomal translocations in human cancer may result in products that can be suppressed by targeting drugs. An example is bcr-abl tyrosine kinase in chronic myelogenous leukemia that can be treated with imatinib mesylate. However, the mechanisms of translocations or exchanges of chromosomal segments are virtually unknown. In this summary, chromosomal translocations in human cancer are compared with ‘crossing over’ of chromosomal segments occurring during the first meiotic division. Several proposed mechanisms of the exchange of DNA between and among chromosomes are discussed. The conditions that appear essential for these events to occur are listed. Among them are proximity of the involved DNA segments, mechanisms of excising the target DNA, its transport to the new location, and integration into the pre-existing chromosome. The conclusion based on extensive review of the literature is that practically nothing is known about the mechanism of ‘crossing over’ or translocation. Based on prior work on normal human cells, it is suggested that only one of the two autosomes participates in these events that may include loss of heterozygozity, another common abnormality in human cancer. Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Presents information on vibration exciters for low frequency structures. Background on vibration shakers; Description of inertial shakers; Details of the base and broadband excitation of a structure; Information on inertial mass exciters; Discussion on step relaxation technique.

The complex detection system leading to the discovery and treatment of precancerous lesions and early cancer of the uterine cervix is described in detail and discussed. By far the most difficult and underestimated component of this system is the screening and interpretation of cervical (Papanicolaou) smears. Cytologic case finding may fail because of inadequate samples, insufficient time devoted to screening, or human fatigue. Other weak points of the system, such as an inadequate clinical component, inadequate patient compliance, poor reproducibility of diagnoses, and ineffective aftercare, are also described. For example, obtaining a second smear to confirm or refute a diagnosis of cellular atypia is often a misleading practice. Although this cancer detection system has been shown to be effective in reducing the rate of morbidity and mortality from invasive cervical cancer in appropriately screened populations, there is no evidence that the Papanicolaou test has succeeded anywhere in complete eradication of this theoretically preventable disease. It is important to inform the public about the potential failures of the system and the reasons for them. [ABSTRACT FROM AUTHOR]

In normal human terminally differentiated and polarized bronchial cells, the fluorescent “painting” technique (FISH) for all chromosomes (except Y) documented that each homologue of each chromosome occupies a distinct, separate domain within the nucleus. The homologues are distributed along the nuclear membrane. In most cells and chromosomes studied, the two homologues were not identical: one was usually more “compact” than the other which was more “open,” displaying fiber-shaped extensions. The differences between the territories of homologues 1 and 7 were shown to be statistically valid (P < 0.0001 by Wilcoxon sign rank test), as has been previously documented for the two X chromosomes (Eils et al., 1996). In some parallel arrays of bronchial cells, the position of the chromosomes in the nuclei was either identical or formed a mirror image, suggesting that the position of the chromosomes in polarized nuclei may be constant. To confirm this observation, the angles formed by the two homologues in the polarized oval nuclei were measured for chromosomes 1, X, and 7. The measurements disclosed that, in about two-thirds of the nuclei, the two homologues formed angles of 150°, 157° and 148°, nearly identical to those formed by the same three chromosomes in prometaphase rosettes of cultured diploid human fibroblasts (Nagele et al., 1995). In about one third of the nuclei, the same homologues formed angles of 89°, 72°, and 94°, and occasionally an angle of 180°. A three-dimensional computer reconstruction of the nuclei was performed using the data for the X chromosomes. By cinematographic technique, it could be documented that the angles separating the two homologues depended on the rotation of the nucleus along the axes X, Y, and Z. The cause of the rotation is speculative at this time. Because of the concordance of these data in terminally differentiated epithelial cells with prior observations on prometaphases of human diploid fibroblasts, it is suggested that the position of chromosomes in all human cells is constant throughout the cell cycle. The possible significance of these observations is discussed. [ABSTRACT FROM AUTHOR]

Background: Epidemiologic studies have suggested that vitamin E and beta-carotene may each influence the development of prostate cancer. In the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, a controlled trial, we studied the effect of alpha-tocopherol (a form of vitamin E) and beta-carotene supplementation, separately or together, on prostate cancer in male smokers.Methods: A total of 29133 male smokers aged 50-69 years from southwestern Finland were randomly assigned to receive alpha-tocopherol (50 mg), beta-carotene (20 mg), both agents, or placebo daily for 5-8 years (median, 6.1 years). The supplementation effects were estimated by a proportional hazards model, and two-sided P values were calculated.Results: We found 246 new cases of and 62 deaths from prostate cancer during the follow-up period. A 32% decrease (95% confidence interval [CI] = -47% to -12%) in the incidence of prostate cancer was observed among the subjects receiving alpha-tocopherol (n = 14564) compared with those not receiving it (n = 14569). The reduction was evident in clinical prostate cancer but not in latent cancer. Mortality from prostate cancer was 41% lower (95% CI = -65% to -1%) among men receiving alpha-tocopherol. Among subjects receiving beta-carotene (n = 14560), prostate cancer incidence was 23% higher (95% CI = -4%-59%) and mortality was 15% higher (95% CI = -30%-89%) compared with those not receiving it (n = 14573). Neither agent had any effect on the time interval between diagnosis and death.Conclusions: Long-term supplementation with alpha-tocopherol substantially reduced prostate cancer incidence and mortality in male smokers. Other controlled trials are required to confirm the findings. [ABSTRACT FROM AUTHOR]