Asparaginase, however, catalyzes the conversion of L-asparagine to aspartic acid and ammonia. This deprives the leukemic cell of circulating asparagine, which leads to cell death. Enzyme regulation
Type I L-asparaginase protein may use the morpheein model of allosteric regulation. Cost
Normal asparaginase costs less than its pegylated version, pegaspargase. However, because it doesnt stay as long in the body, the injections need to be more frequent, with the result that total cost of treatment may be lower for the pegylated version. History
The discovery and development of asparaginase as an anti-cancer drug began in 1953, when scientists first observed that lymphomas in rat and mice regressed after treatment with guinea pig serum. Later it was found out that it is not the serum itself which provoke the tumour regression, but rather the enzyme asparaginase.After researchers comparing different kinds of asparaginases, the one derived from Escherichia coli and Erwinia chrysanthemi turned out to have the best anti-cancer ability. E. coli has thereby become the main source of asparaginase due to the factor that it is also easy to produce in large amount. Society and culture
Names
Crisantaspase is the British Approved Name (BAN) for asparaginase obtained from Erwinia chrysanthemi. Colaspase is the BAN of asparaginase obtained from Escherichia coli. The United States Adopted Name of crisantaspase is asparaginase Erwinia chrysanthemi. Elspar, Kidrolase, Leunase and Spectrila are brand names for colaspase, while Erwinase and Erwinaze are brand names for crisantaspase. The pegylated version of colaspase is called pegaspargase. Oncaspar is the brand name of pegaspargase.
Pimecrolimus is an immunomodulating agent of the calcineurin inhibitor class used in the treatment of atopic dermatitis (eczema). It is available as a topical cream, once marketed by Novartis (however, Galderma has been promoting the compound in Canada since early 2007) under the trade name Elidel. Medical uses
It has been proven to be effective in various inflammatory skin diseases, e.g., seborrheic dermatitis,  cutaneous lupus erythematosus, oral lichen planus,  vitiligo, and psoriasis. Tacrolimus and pimecrolimus are both calcineurin inhibitors and function as immunosuppressants. Side effects
In January 2006, the United States Food and Drug Administration (FDA) announced that Elidel packaging would be required to carry a black box warning regarding the potential increased risk of lymph node or skin cancer, as for the similar drug tacrolimus, whereas current practice by UK dermatologists is not to consider this a significant real concern and they are increasingly recommending the use of such new drugs.Importantly, although the FDA has approved updated black-box warning for tacrolimus and pimecrolimus, the recent report of the American Academy of Dermatology Association Task Force finds that there is no causal proof that topical immunomodulators cause lymphoma or nonmelanoma skin cancer, and systemic immunosuppression after short-term or intermittent long-term topical application seems an unlikely mechanism. Another recent review of evidence concluded that postmarketing surveillance shows no evidence for this systemic immunosuppression or increased risk for any malignancy. However, strong debates and controversies continue regarding the exact indications of immunomodulators and their duration of use in the absence of active controlled trials.