Transcription. Is S phase important for transcriptional silencing?

Does the cell-brain theory work in explaining carcinogenesis?

As a major microtubule-organizing center, the centrosome, together with the embedded centrioles and connecting filaments (or microtubules), has lately been proposed to be the "brain" of a cell. Although there are a lot of works to be done to test this hypothesis, emerging data have suggested that this centrosome-centered "cell brain" is playing increasingly important roles in cell control. Genes seem not to tell the whole story, despite the commonly held view that genetic alteration is the cause of most medical problems including cancer development. Although the mechanisms through which gene expression and protein synthesis are regulated remain to be studied, current advances in our understanding of the roles of the centrosome in the regulation of DNA synthesis, DNA repair, cell cycle, apoptosis and in the maintenance of genetic stability are challenging our tradition thoughts. Genetic alterations may be repaired by the centrosome-centered "cell brain"-mediated self-defense, but the cell brain defects intend to cause genetic alterations, which, in turn, may result in cancer development. Further understanding of the roles of the centrosome/cell brain in these and other new aspects are becoming very helpful in comprehending why and how medical problems including tumors develop. Meanwhile, it suggests that great attention should be given to the centrosome/cell brain, instead of gene alone when treating medical problems, which is discussed in this paper on the basis of cell brain theory and may prove helpful in shedding light on the often paradoxical observations seen in cell control, particularly in cancer development.

Antigenic variation in Plasmodium falciparum is associated with movement of var loci between subnuclear locations

Much of the success of Plasmodium falciparum in establishing persistent infections is attributed to immune evasion through antigenic variation. This process involves periodically exchanging variants of the major surface antigen PfEMP1, a protein also responsible for parasite cytoadherence. PfEMP1 is encoded by genes of the 60-member var family, located at subtelomeric and internal chromosome loci. The active or silenced state of var genes is heritable, and its control by nonsequence information remains puzzling. Using FISH analysis, we demonstrate that both internal and subtelomeric var genes are positioned at the nuclear periphery in their repressed state. Upon activation, the same var genes are still found in the periphery, indicating that this zone can be transcriptionally competent, rather than uniformly silenced. However, activation of a var gene is linked with altered positioning at the nuclear periphery, with subtelomeric var loci exiting chromosome end clusters and being relocated to distinct nuclear sites. Serial sectioning of parasite nuclei reveals areas of both condensed and noncondensed chromatin at the nuclear periphery. Our results demonstrate that regulation of antigenic variation is associated with subnuclear position effects and point to the existence of transcriptionally permissive perinuclear zones for var genes.

Animal ethical evaluation: an observational study of Canadian IACUCs

Three Canadian institutional animal care and use committees were observed over a 1-year period to investigate animal ethical evaluation. While each protocol was evaluated, the observer collected information about the final decision, the type of protocol (research vs. teaching), and the category of invasiveness. The observer also wrote down verbatim all verbal interventions, which were coded according to the following categories: scientific, technical, politics, human analog, reduction, refinement, and replacement. The data revealed that only 16% of the comments were devoted to the 3 explicit ethical categories (i.e., reduction, refinement, and replacement) and that most of the comments were technical. However, the analysis revealed that ethical concerns were implicit in both scientific and technical language, or some of the scientific and technical comments had an impact on the ethical treatment of animals. The results are discussed in relation to previous nonobservational research that identified potential pitfalls and bias in animal ethical evaluation.

The centrosome-centered cell-brain in apoptosis

Apoptosis (or programmed cell death) is one of the central cellular processes in development, stress response, aging, carcinogenesis, and disease in multi-cellular eukaryotes. Although great effort has been made, the detailed mechanism through which apoptosis is initiated is yet unclear. Previously, the centrosome, or more explicitly the complex comprising the centrosome, centrioles, and connecting filaments, was reported to be required for apoptosis. It may be through this 'cell brain', reminiscent of the long known brain of animals (or humans), that complicated cellular processes, including apoptosis, are precisely coordinated. In this paper, the latest data to support this contention are scrutinized.

Cell brain abnormalities in cancer development

Cancer has long been regarded as a genetic disease. Therefore, current theories on cancer development focus on genetic alterations affecting oncogenes or tumor suppressor genes. However, the mechanisms through which genetic alterations are induced are largely unknown. In this paper a theory will be developed which interprets cancer as a cell brain illness rather than a genetic disease. The complex comprising the centrosome, normally two centrioles and connecting filaments, was recently termed the 'cell brain', and was found to determine a cell's fate. It is through the cell brain, instead of the genes, that genetic stability and expression are maintained and regulated. Accordingly, the nucleus is regarded as a safe storage for inheriting materials (genes) that primarily act as manufacturing templates. Therefore, cancer should be regarded as a 'brain illness' of a cell, instead of a genetic disease, which is strongly supported by the latest evidence, as discussed in this paper. Such a theory serves to better clarify the confusing observations in cancer development accumulated over the last decades.

Cell brain: a new focus in the postgenomic era

The centrosome, together with the embedded centrioles and connecting filaments, has come to be regarded as the 'brain' of a cell, analogous to the long known brain of an animal or a human being. It is through the 'brain' that different cellular activities are coordinated as a whole. In this article, comparative studies of the principles of life at varying levels and of the new roles of different cellular organelles in maintaining a healthy life for an organism provide further support to this theory, which is discussed based on the latest findings. Hopefully, this new theory can make a great contribution to break the paradigm of nucleus (or genes) as causes of all problems.

A study of three IACUCs and their views of scientific merit and alternatives

Two ethical issues facing Institutional Animal Care and Use Committees [IACUCs] today are assessing scientific merit and the use of alternatives in research proposals. This study evaluated 3 IACUCs using a 19-question survey, with a 77.8% response rate. Although 76% of members answered that scientific merit should be more dili-gently assessed if more than slight pain is caused, 14% believed that assessing scien-tific merit is not the role of the IACUC. Nearly 86% agreed that the search for alterna-tives should be more diligent for protocols that incur more than slight pain to the animals involved. Some members believed that alternatives were not actively enough sought after, while others believed no viable alternatives existed. Additional guide-lines are needed to clarify these issues.

Cell brain crystallization for cancer therapy

Cancer remains one of the leading causes of death throughout the world. One of the important reasons why conventional treatments fail is the development of resistance to therapeutics. The dual effect concept and self-defense mechanism plus the threshold theory might in part explain the development of resistance, however, the primary cause is unclear. A novel theory, 'cell brain', where, selective crystallization of the 'brain' of a cell (comprising centrosome, centrioles and the connecting filaments) occurs, may be a potential alternate approach to cancer therapy.

Detection of proliferating S-phase brain tumor cells by in situ DNA replication

OBJECT

Current methods used to describe the proliferative status of brain tumors rely on labor-intensive, potentially costly procedures. This article provides a description of a rapid, inexpensive, uncomplicated technique used to identify proliferating cells in tissue obtained at the time of resection.

METHODS

Touch preparations of 16 fresh astrocytic tumors and four fresh healthy temporal neocortical tissue samples were obtained at the time of surgery. Slides were placed in hypotonic potassium chloride to permeabilize their membranes, incubated in nucleotide precursors, and labeled with bromodeoxyuridine; they were later examined with the aid of a fluorescence microscope. The percentage of tumor cells in the S phase increased in conjunction with the grade of tumor and corresponded with the findings of immunohistochemical staining for the cell-cycle marker MIB-1. These results were confirmed in cell culture by using normal human astrocytes and two glioma cell lines. Slides can be analyzed in as little as 30 minutes after removal of tissue during surgery.

CONCLUSIONS

In this study the authors describe a simple method by which cells in the S phase of the cell cycle. which are contained in fresh tumor obtained at the time of surgery, can be labeled. This method may prove a useful adjunct to frozen-section analysis and may permit discrimination of neoplastic tissues from other tissues observed in small specimen samples.