Exogenous chemicals

Most of any exogenous chemical absorbed from the GI tract must pass through the liver via the hepatic-portal system (leading to the so-called first-pass effect) and, as mixing of the venous blood with arterial blood from the liver occurs, considera-... 

Changes in the urinary excretion of D-glucaric acid and decreased serum levels of p,p DDE (dichloro-diphenyl dichloroethene a metabolite of DDT) observed in endrin workers were interpreted to signify induction of hepatic enzymes responsible for the metabolism of endogenous and exogenous chemicals (Hunter etal. 1972). 

Selected references of GC-based methods for the analyses of endogenous and exogenous chemicals of neuroblological Interest... 

Neurosteroids (in this book) Exogenous Chemicals Amphetamine, methamphetamlne. Pentafluorobenzyl bromide Bis(trimethylsilyl) trifluoroacetamide El Purdy et al. (2006) Yonamine et al. 

Exogenous Chemicals Neuroleptics Risperidone and its metabolites Moody et al. (2004)... 

Nowadays, one stated objective of much of the more imaginative mastitis research is the reduction in our dependence on antibiotics and other exogenous chemicals to control bovine mastitis. Achievement of this goal is nowhere in sight. And so, we are left dependent upon antimicrobial therapy, despite its many limitations, as a major element in control strategy for bovine mastitis. 

Active efflux transporters also exist in the placenta, analogous to the gut and blood-brain barrier. These are Pgp, multidrug resistance-associated protein (MRP), and breast cancer resistance protein (BCRP). These transport proteins are located in many tissues but also appear to be expressed in the placenta. Though the substrate specificities of these proteins have not been completely described, they appear to function as efflux transporters, moving endogenous and exogenous chemicals from the placental cells back to the systemic circulation. In this way, they serve as a mechanism to protect the fetus from exposure to unintended chemicals. 

Vitamins are exogenous chemical substance required by the body in very small amount for the various metabolic functions of the body and categorized as essential nutrients. They do not yield energy but enable the body to use other nutrients and are primarily used in the prevention and treatment of certain deficiency diseases. 

The notion of using exogenous chemicals to control plant growth, and hence productivity, is not new. Many of the first commercial herbicides (auxin herbicides) were developed as a direct consequence of plant growth regulator research (see Chapter 1, Section 3.3). 

Mammary gland size, milk production and release and histology can be affected adversely by toxic agents, and many exogenous chemicals and drugs are transferred into milk (WHO, 1988 American Academy of Pediatrics Committee on Drugs, 1994 Sonawane, 1995 LaKind et al., 2001). 

Endocrine disrupting chemicals Exogenous chemicals that alter functions) of the endocrine system and consequently cause adverse health effects in an intact organism, its progeny or (sub)populations. 

Errors of omission. The major causes of cancer (other than smoking) do not involve exposures to exogenous chemicals that cause cancer in high-dose tests rather, the major causes are dietary imbalances, hormonal factors, infection and inflammation, and genetic factors. Insufficiency of many vitamins and minerals, which is preventable by supplementation, causes DNA damage by a mechanism similar to radiation. 

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