Organs and systems

Toxicologists tend to focus their attention primarily on c.xtrapolations from cancer bioassays. However, tlicrc is also a need to evaluate the risks of lower doses to see how they affect the various organs and systems in the body. Many scientific papers focused on tlic use of a safety factor or uncertainty factor approach, since all adverse effects other than cancer and mutation-based dcvclopmcnUil effects are believed to have a tlu cshold i.e., a dose below which no adverse effect should occur. Several researchers have discussed various approaches to setting acceptable daily intakes or exposure limits for developmental and reproductive toxicants. It is Uiought Uiat an acceptable limit of exposure could be determined using cancer models, but today tliey arc considered inappropriate because of tlircsholds. ... 

Insurers are aware of the importance of a management that, at all levels, is fully conscious of the fire and other hazards within its premises and consequently acts in a highly responsible way. An opinion of the standard of management is an important part of the insurance surveyor s report referred to earlier, and is obtained by observation of conditions in the premises and a scrutiny of the organization and systems that are in operation. 

To implement the Physiome Project, a lot of good science (Wolpert) and thinking (Dover) will be required. The tools that will ultimately define the success of the project are analytical models of biological processes that have predictive power - virtual cells, tissues, organs and systems. 

Table I. Chief Effects of Economic Poisons on Tissues, Organs, and Systems of Man...

To optimize chemotherapy administration, the clinician must identify, monitor, treat, and prevent or minimize treatment-related toxicity. Pertinent laboratory data and other procedures should be reviewed to establish a baseline for monitoring purposes. Major organ and system toxicities to be monitored include hematologic, neurologic, skin, pulmonary, GI, renal, and cardiac. 

Dioxin is a poison of polytropic action, affecting actually all the organs and systems of the body. The most typical manifestations of dioxin poisoning are skin affections, such as chloracne. 

Figure 2.1 depicts in schematic form the relationships among certain organs and systems of the body essential for an understanding of ADME. The arrows in the figure depict the various paths chemicals follow when they enter the body, move around within it, and are finally excreted from it. It will be helpful to refer to the figure throughout the course of this chapter. 

In Chapter 2 we explained how chemicals foreign to the body can enter the circulatory system and be transported to various parts of the body. If the concentrations of these substances or their metabolic products reach sufficiently high levels, systemic toxicity can result. Different chemicals affect different organs and systems of the body because of differences in the rate and manner of their absorption, distribution, metabolism, and excretion. Some chemicals are directly toxic to the elements of the blood. Others bring about changes in certain elements of the blood that become detrimental to other systems of the body. 

Koshash Wouldn t it be the other way round Don t you think that the circadian system has co-opted the complex neuroendocrine systems such as the HP axis that exist in mammals Presumably much of the integration in mammals — the nonautonomy of the systems — makes use of the complex neuroendocrine relationships between organs and systems. Then the question is, if those systems existed first, might the circadian system have taken advantage of them ... 

Children are exposed to PBBs and PBDEs in the same manner as the general population, primarily via coiisiiinptioii of contaminated foods. Exposure also may occur by transfer of PBBs and PBDEs that have accumulated in women s bodies to the fetus across the placenta. Because PBBs and PBDEs are lipophilic substances, they can additionally accumulate in breast milk and be transferred to nursing infants. Placental transfer, although it may be limited in absolute amounts, is a concern because of possible effects of PBBs and PBDEs on sensitive immature tissues, organs, and systems, with potentially serious long-lasting consequences. Transfer of PBBs and PBDEs via breast milk could be relatively considerable and, like prenatal exposure, has the potential to contribute to altered development. 

The knowledge gained from this novel cell transplantation device will allow us to expand the technology to other organs and systems, for example, an artilicial pancreas, kidney, or extracorporeal bone marrow system. Nevertheless, Yuang offers a glimpse of what would be required of a scaffold for use in a cell transplant device. 

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