Foreign protein toxicity

Plasmid instability can arise when the foreign protein is toxic to the host cell. During rapid growth plasmids may be lost or the copy number reduced, allowing the non-recombinant cells to take over. As a... 

Since plastids have a limited set of protein degradation pathways, foreign proteins that exhibit harmful effects to the plant in the cytoplasm may be more stable when they accumulate within the chloroplast (Heifetz, 2000). For example, the vaccine protein cholera toxin B subunit was shown to be toxic even when it accumulated to very low levels within the plant cytoplasm, but was nontoxic when it accumulated to large quantities within the chloroplast. Plastids also possess the ability to form disulfide bonds, a requirement for many correctly folded mammalian proteins (Daniell et al., 2005a). These properties have made them attractive for the production of biopharmaceuticals in plants. 

Adverse effects Toxicities include a range of hypersensitivity reactions (since it is a foreign protein), a decrease in clotting factors, and liver abnormalities, as well as pancreatitis, seizures, and coma due to ammonia toxicity. 

Toxic effects of metabolites from drug degradation do not need to be monitored for immunotoxins (per IHC S6). As a recombinant protein, immunotox-ins entering the human body are quickly degraded to small peptides and amino acids in the blood by proteases that specifically target foreign proteins and are cleared by the kidney. 

Although inflammation is essentially a normal defensive mechanism (a reaction to tissue injury, infection, inhalation of foreign proteins), the manifestations may be so serious and inappropriate or Involve such discomfort, that treatment with antiinflammatory agents is required. Inflammatory conditions can be acute (as in insect stings) or chronic (chronic asthma, dermatitis and other skin conditions, rheumatoid conditions). A wide range of drugs may be used to treat one or other inflammatory condition, and potential toxicity in relation to the medical condition is an important determinant of choice. 

Toxicity can be extensive. Since the enzyme is a foreign protein, hypersensitivity reactions, including anaphylaxis, are to be expected. Neurotoxicity, hepatotoxicity, hyperglycemia (decreased insulin production ), pancreatitis, and myelosuppression are also encountered. 

L-Asparaginase has minimal effects on bone marrow and gastrointestinal mucosa. Its most serious toxicities result from its antigenicity as a foreign protein and its inhibition of protein synthesis. Hypersensitivity reactions occur in 5 to 20% of patients and may be fatal. 

Potential toxicity of introduced foreign proteins of the whole food ... 

Many food constituents are potentially toxic to the animal consuming them. Microbial contaminants are an obvious example the digestive enzymes kill many bacteria, but some organisms may damage the gut, which allows them or the toxins they produce to invade the animal s tissues. Foreign proteins, especially those with endocrine activity, could harm the animal if absorbed, but the gut provides an effective barrier to prevent their absorption before they are hydrolysed. The same is true of nucleic acids (whose breakdown is a matter of concern, as some animal foods may now be derived from genetically modified plants). Some of the toxic constituents of pasture plants are broken down in the rumen of cattle, sheep and goats (see p. 494). As mentioned above, the animal body avoids excessive intake of the mineral elements calcium and iron by selective absorption. 

The efficiency of the human digestive process in health is such that about 96 per cent, of the total mixed dietary is made available for absorption into the portal and lymphatic systems. Colloids have been converted into diffusible solutes, insoluble fats have been emulsified and saponified, compound saccharides have been changed into utiUsable monosaccharides, and foreign proteins have been rendered non-toxic by being hydrolysed into non-specific mixtures of amino acids. 

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