Tissue and corneal donation and transplantation in the UK.

NHS Blood and Transplant (NHSBT) was established in 2005 as a Special Health Authority when the National Blood Authority and UK Transplant merged. This helped to bring tissue banking and organ transplantation services under one umbrella organization. This merger means that ~!95% of all deceased donors (whether tissue, organ or both) are now facilitated by one organization. NHSBT Tissue Services is the largest tissue establishment in the UK, and is a multi-tissue bank that specializes in the consent, retrieval, processing, storage, and dispatch of donated tissue coordinated from a purpose built, state-of-the-art tissue bank in Liverpool. Tissue donations can come from either tissue-only donors or solid organ donors who also donate tissue. Annually there are ~450 multi-tissue donors and 2500 eye donors in the UK, resulting in many thousands of transplants, including 3564 cornea transplants in 2010-2011. The separation of tissue- and organ-specific donors is largely artificial, and while organ transplantation can be life-saving, tissue transplantation can also have a dramatic effect on a patient's quality of life. It is hoped that all donors, both organ and tissue, will be recognized for the gift they make to society after their death.

Kinetic origin of the chelate effect. Base hydrolysis, H-exchange reactivity, and structures of syn,anti-[Co(cyclen)(NH3)2]3+ and syn,anti-[Co(cyclen)(diamine)]3+ ions (diamine = H2N(CH2)2NH2, H2N(CH2)3NH2).

The synthesis of syn,anti-[Co(cyclen)en](ClO4)3 (1(ClO4)3) and syn,anti-[Co(cyclen)tn](ClO4)3 (2(ClO4)3) is reported, as are single-crystal X-ray structures for syn,anti-[Co(cyclen)(NH3)2](ClO4)3 (3(ClO4)3). 3(ClO4)3: orthorhombic, Pnma, a = 17.805(4) A, b = 12.123(3) A, c = 9.493(2) A, alpha = beta = gamma = 90 degrees, Z = 4, R1 = 0.030. 1(ClO4)3: monoclinic, P2(1)/n, a = 8.892(2) A, b = 15.285(3) A, c = 15.466(3) A, alpha = 90 degrees, beta = 91.05(3) degrees, gamma = 90 degrees, Z = 4, R1 = 0.0657. 2Br3: orthorhombic, Pca2(1) a = 14.170(4) A, b = 10.623(3) A, c = 12.362(4) A, alpha = beta = gamma = 90 degrees, Z = 4, R1 = 0.0289. Rate constants for H/D exchange (D2O, I = 1.0 M, NaClO4, 25 degrees C) of the syn and anti NH protons (rate law: kobs = ko + kH[OD-]) and the apical NH, and the NH3 and NH2 protons (rate law: kobs = kH[OD-]) in the 1, 2, and 3 cations are reported. Deprotonation constants (K = [Co(cyclen-H)(diamine)2+]/[Co(cyclen)(diamine)3+][OH-]) were determined for 1 (5.5 +/- 0.5 M-1) and 2 (28 +/- 3 M-1). In alkaline solution 1, 2, and 3 hydrolyze to [Co(cyclen)(OH)2]+ via [Co(cyclen)(amine)OH)]2+ monodentates. Hydrolysis of 3 is two step: kobs(1) = kOH(1)[OH-], kobs(2) = ko + kOH(2)[OH-] (kOH(1) = (2.2 +/- 0.4) x 10(4) M-1 s-1, ko = (5.1 +/- 1.2) x 10(-4) s-1, kOH(2) = 1.0 +/- 0.1 M-1 s-1). Hydrolysis of 2 is biphasic: kobs(1) = k1K[OH-]/(1 + K[OH-] (k1 = 5.0 +/- 0.2 s-1, K = 28 M-1), kobs(2) = k2K2[OH-]/(1 + K2[OH-]) (k2 = 3.5 +/- 1.2 s-1, K2 = 1.2 +/- 0.8 M-1). Hydrolysis of 1 is monophasic: kobs = k1k2KK2[OH-]2/(1 + K[OH-1])(k-1 + k2K2[OH-]) (k1 = 0.035 +/- 0.004 s-1, k-1 = 2.9 +/- 0.6 s-1, K = 5.5 M-1, k2K2 = 4.0 M-1 s-1). The much slower rate of chelate ring-opening in 1, compared to loss of NH3 from 3, is rationalized in terms of a reduced ability of the former system to allow the bond angle expansion required to produce the SN1CB trigonal bipyramidal intermediate.