Cyclosporine characterization

Page, A.P., Landry, D., Wilson, G.G. and Carlow, C.K.S. (1995b) Molecular characterization of a cyclosporin A-insensitive cyclophilin from the parasitic nematode Brugia malayi. Biochemistry 34, 11545-11550. 

While changes in cell phenotypes have proved useful in some settings to characterize the immunotoxicity of xenobiotics,1 phenotypic analysis alone is often not a sensitive indicator of low dose immunotoxicity for many agents that alter immune function. Xenobiotics that exert selective toxicity on lymphoid and myeloid cells may be discovered through immunophenotypic analysis. However, most agents produce immunotoxicity at doses much lower than those required to produce cytotoxicity or interfere with primary lymphoid organ differentiation. Some of the most potent immunosuppressive chemicals that have been tested, such as cyclosporine A, do not alter immunophenotype at doses that are immunosuppressive. On the other hand, when phenotyping is linked to assessment of functional parameters of the cells, immunotoxic effects are more likely to be identified. 

Kawazu K, Yamada K, Nakamura M, Ota A. Characterization of cyclosporin a transport in cultured rabbit corneal epithelial cells P-glycoprotein transport activity and binding to cyclophilin. Invest Ophthalmol Vis Sci 40 1738-1744 (1999). 

In linear NRPSs a product consisting of amino acids is biosynthesized in an N- to C-terminal manner by the multidomain assembly line with a domain organization of A-PCP-(C-A-PCP) i-TE. The initiation module of a linear NRPS lacks a C domain, while the following modules may include any required additional domains. After formation of the full-length peptide, the product is released from the assembly line by a termination domain. Thus, the number and order of amino acids in the peptide directly coincides with the number and order of synthetase modules. Many NRPs are biosynthesized in this manner, and characterized examples include the penicillin tripeptide precursor -(L-0 -aminoadipyl)-L-cysteinyl-D-valine (ACV, Figure 4 (a)), complestatin, cyclosporin, fengycin, surfactin, and tyrocidine. "... 

The cyclosporins are a group of cyclic peptides produced by fungi such as Cylindrocarpon lucidum and Tolypocladium inflatum. These agents show a rather narrow range of antifungal activity, but high levels of immunosuppressive and anti-inflammatory activities. The main component from the culture extracts is cyclosporin A, but some 25 naturally occurring cyclosporins have been characterized. 

Nephrotoxicity Nephrotoxicity has been noted in 25% of cases of renal transplantation, 38% of cases of cardiac transplantation, and 37% of cases of liver transplantation. Mild nephrotoxicity was generally noted 2 to 3 months after transplant and consisted of an arrest in the fall of the preoperative elevations of BUN and creatinine at a range of 35 to 45 mg/dL and 2 to 2.5 mg/dL, respectively. These elevations are often responsive to dosage reductions. More overt nephrotoxicity was seen early after transplantation and was characterized by a rapidly rising BUN and creatinine. Because these events are similar to rejection episodes, care must be taken to differentiate between them. This form of toxicity is usually responsive to cyclosporine dosage reduction. 

Hall B, Jelbart ME, Gurley KE, Dorsch SE. 1990. Specific unresponsiveness in rats with prolonged cardiac allograft survival after treatment with cyclosporine. III. Further characterization of CD4+ suppressor cell and its mechanisms of action. J Exp Med. 171 141-157. 

Meyer, K., Fobker, M., Christians, U., Erren, M., Sewing, K. F., Assmann, G., and Benninghoven, A. (1996). Characterization of glucuronidated phase II metabolites of the immunosuppressant cyclosporine in urine of transplant patients using time-of-flight secondary-ion mass spectrometry. Drug Metab. Dispos. 24 1151-1154. 

Tamilvanan, S., et al. 2001. Ocular delivery of cyclosporin A.I. Design and characterization of cyclosporin A-loaded positively charged submicron emulsion. STP Pharm Sci 11 421. 

Sgoutas et al. [151] determined the cyclosporine distribution in plasma from fasted and nonfasted patients, and these data are shown in Table 8. An increased proportion of cyclosporine was associated with the TRL in the nonfasted state compared with fasted patients with a corresponding decrease in LDL and HDL CY levels. An extreme example of altered cyclosporine plasma distribution has also been reported in a case study of a patient with severe hypertriglyceridemia [152], This was characterized by huge increases in plasma chylomicron concentrations (with plasma TG concentrations concentrations up to 264 mg/ mL-1) and much higher than expected plasma concentrations of cyclosporine (considering the dose), of which up to 83% was associated with the chylomicrons. 

Figure 2 Order and organization of enniatin synthetase and cyclosporin synthetase as deduced from gene sequence and biochemical characterization. Symbols in the adenylateforming modules (black boxes) indicate the corresponding activated amino acids. M stands for A -methyltransferase domain. Condensation domains are represented by white boxes. (A) Top Structure of enniatin synthetase. EA represents the D-Hiv-activating module EB represents the L-valine-activating module D-Ehv is D-2-hydroxyisovaleric acid. Bottom Structural features of the wild-type A -methyltransferase domain M of esynl. The black boxes indicate conserved motifs which can be found within methyltransferases and A -methyltransferase domains of peptide synthetases (see also Fig. 3). The numbers indicate the amino acid position in the sequence of Esyn. (B) Structure of cyclosporin synthetase. Abu = L-a-aminobutyric acid Bmt = (4A)-4-[(E)-2-butenyl]-4-methyl-L-threonine.

K Hoffmann, E Schneider-Scherzer, H Kleinkauf, R Zocher. Purification and characterization of eucaryotic alanine racemase acting as key enzyme in cyclosporin biosynthesis. J Biol Chem 17 12710-12714, 1994. 

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