Cytologicals events

The book is divided into 3 sections. Section I.Cellular Model Systems, includes 3 chapters (Allelopathy and plant cell diagnostics, Cellular models as biosensors and microalgae for determining the effects of allelochemicals). Section II. New Methods of Microscopy has 5 chapters (Microscopic methods to study morpho-cytological events during the seed germination,... 

Microscopic Methods to Study Morpho-cytological Events during the Seed Germination... 

We will now turn to a short description of the cytological events... 

Further studies have implicated BRCAl in the cellular response to DNA double-stranded breaks (DSBs), a potentially lethal form of DNA damage. Cells defective in BRCAl possess numerous cytological and biological features that have been known for years to be correlated with perturbation in the maintenance of chromosome stability. This includes aneuploidy, centrosome amplification, spontaneous chromosome breakage, aberrant recombination events, sensitivity to ionizing radiation, and impaired cell cycle checkpoints. In addition, a variety of experiments have demonstrated roles for BRCAl in enforcing the GfM cell cycle transition, homologous recombination between sister chromatids, as well as the restart of stalled replication in S phase. 

Mechanistic data for cancer are considered in hazard characterization in the context of mode of induction of toxic effects. A postulated mode of action is a biologically plausible sequence of key events leading to an observed effect supported by robust experimental observations and mechanistic data. It describes key cytologi-cal, genetic, and biochemical events— that is, those that are both measurable and necessary to the observed effect. Mode of action is contrasted with mechanism of action, which generally involves a much greater understanding of the molecular basis for an effect. 

Cytologically, the major alteration caused by viruses in localized infection is chromosome breaks. As a result of infection, the virus cell ceases to proliferate and dies. Whether this is a direct effect of chromosome break or an indirect event resulting from ischemia caused by swelling and proliferation of capillary endothelial cells remains to be seen. But if chromosome breaks are responsible for cellular death, then the sequence of molecular events that leads from such damage to interference with cellular proliferation and death remains to be clarified. 

After PDT, patients were followed by regular cystoscopy for up to 21 months to assess time to recurrence. Reported adverse events were coded according to the WHO Adverse Reactions Technology. Efficacy was assessed by cystoscopy, cytology and histology, and was defined as the number of patients who were tumoxu- free at 6 or 21 months after initial PDT treatment... 

Lastly, we want to report on some experiments designed to examine in more detail the events, both cytological and biochemical, involved in the conversion of a normal to an abn culture. 

During the prophase the two most prominent events are the coiling and associated condensation of the chromosomes so that they become cytologically defined and the disappearance from the nucleolus (or nucleoli) of the RNA which is a prominent constituent of this structure during interphase. Often the nucleoli completely disappear as they become separated from the nucleolar organiser regions of the chromosomes during prophase condensation of the chromosomes. Then towards the end of prophase the nuclear envelope breaks down. 

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