Recombinant technologies

Gene cloning is a method that uses recombinant technology to insert a gene into a vector DNA (plasmid obtained from a bacterium). The modified vector is put back into the bacterium, which then reproduces endlessly (clones) the new gene as well as the others in the vector. 

One technology uses bovine somatotropin (bST) produced by recombinant technology (38). Somatotropin [9002-72-6] is a growth hormone. The bST-supplemented cows provide an increase in milk output per cow or an increased feed efficiency. Recombinant bST, also known as recombinant bovine growth hormone (rBGH) is the synthetic analogue of a natural hormone that increases milk production in cows (39). The use of recombinant technology was approved by the FDA in 1993. The Commission of the European Community has recommended that the moratorium on commercial use of BGH be delayed until the year 2000. 

Another way to enhance the production of an amino acid is to make use of DNA-recombinant technology, often in combination with foe mutations already described. In this way foe negative features of foe micro-organisms are avoided. To help explain this, we will consider a well known fermentation of L-phenylalanine using Escherichia coli. We have already seen foe metabolic pathway leading to foe production of L-phenylalanine in Figure 8.4. 

The prototype of this class is hirudin, which was originally isolated from the salivary glands of the medicinal leech, Hirudo medicinalis. Hirudin itself is not commercially available, but recombinant technology has permitted production of hirudin derivatives, namely lepirudin and desirudin.29,38,41 Lepirudin has a short half-life of approximately 40 minutes after IV administration and 120 minutes when given SC. Elimination of lepirudin is primarily renal therefore, doses must be adjusted based on the patient s renal function. The dose should be monitored and adjusted to achieve an aPTT ratio of 1.5 to 2.5 times the baseline measurement. Lepirudin is currently approved for use in patients with HIT and related thrombosis. Up to 40% of patients treated with lepirudin will develop antibodies to the drug.29,38,41... 

Another, promising avenue to understand silk protein conformation and assembly is the use of model peptides. Although not recent (Fraser and MacRae, 1973 Lotz et al., 1974), studies of silk-based peptide from chemical synthesis, DNA recombinant technology, and computer simulation (Anderson et al., 1994 Asakura et al., 2003 Fahnestock et al., 2000 Fossey et al., 1991 Heslot, 1998 Kaplan, 1998 Wilson et al., 2000) have shown that selected repeats of silk proteins can be transformable hydrogels, elastomers, or regular thermoplastics and that with a proper design they can function as diverse molecular machines (Altman et al., 2003 Heslot, 1998 Kaplan, 1998 Urry, 1998). 

Recombinant selection, 12 517 plasmid vectors for, 12 501 Recombinant technology, 11 11-14 Recombinant therapeutics... 

Determination of protein folding is important in various areas of biotechnology and thus is an area of active research for biopharmaceuticals. Crucial parameters such as activity and stability are related to protein folding. Because improper protein folding occurs with high frequency in proteins produced by recombinant technology and proteins tend to denature upon storage, any technique capable of... 

DiPaolo, B., A. Pennetti, L. Nugent, and K. Venkat (1999). Monitoring impurities in biopharmaceuticals produced by recombinant technology. PSTT 2(2) 70-82. 

The first two antibodies our group tried to express in this vector system within mammalian cells had mistakes in the genetic material that coded for variable regions and, consequently, did not express any antibody at all. The first antibody that was produced by recombinant technology at IDEC using this vector system was in early 1991. It was supposed to be a chimeric anti-CD4 antibody, but the antibody secreted by the cells did not bind to CD4. CD4 is a surface molecule on the leukocytes known as T cells. A primatized antibody (a chimeric antibody where the variable domains are isolated from a cynomol-gus monkey see Figure 32.2) to CD4 was produced later that year. That antibody ended up in clinical trials in humans at the same time as Rituxan. 

Sequence information can be used to clone the target by using recombinant technology. In this way, biochemical pathways of the target can be studied in detail, rendering the development of a drug molecule with higher chances of success. 

Advances in genomics, molecular biology, and recombinant technology have provided new directions for the discovery, development, and manufacture of vaccines. One of the current approaches is a minimalist strategy to decouple the virulence and immunity functions. The aim is to use only the immunity part to confer protection, so that the vaccine is safe to be administered. The approach can be divided into subunit, vector-based, DNA, and peptide vaccines. 

Interferons were extracted and purified from human blood supplies up until the 1980s. The amount produced was very low. Since then, interferons have been produced using recombinant technology from a variety of cells Escherichia coli, fungus, yeast, and mammalian. 

Etanercept is produced by recombinant technology in a Chinese hamster ovary mammalian cell expression system. The WCB is grown in a proprietary media system. The cells are cultured initially in flasks and then inoculated into the bioreactor vessel. The product is purified in a number of chromatographic steps, followed by viral inactivation and viral filtration steps. 

Bacterial and plant toxins toxin fragments Toxic after entry into target cell fragments produced by recombinant technology have been used as targeting moiety and as effector moiety... 

Hemophiliacs are treated with clotting factors when they have severe bleeding episodes, and are also treated to prevent bleeding if surgery or any other activity that might lead to bleeding is planned. Before recombinant technology, the fluid part of normal human... 

Aldesleukin is with recombinant technology prepared interleukin-2 (IL-2). IL-2 binds to the IL-2 receptor and so stimulates proliferation of T-helper cells and cytotoxic T-cells. It also activates macrophages and stimulates B-cell activity. It is used in metastasized renal carcinoma. Life threatening car-diotoxicity may occur. Other adverse effects include bone marrow depression and neurotoxicity with manifestations varying from somnolence to delirium. 

In contrast direct-acting preparations have the ability to inhibit fibrin-bound thrombin and include hirudin derived from medicinal leeches but now produced by recombinant technology. Particular interest centres on ximelagatran which may be a possible... 

Human rPTH (1-34) has been produced by recombinant technologies, is now approved, and will soon be available for the treatment of osteoporosis. It is given subcutaneously, 25 Jig/day cyclically for 12 to 18 months, to increase bone density in individuals with a history of fractures, severe osteopenia, or osteoporosis. PTHrP (1-36) has also been synthesized and is in early clinical trials. 

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