The crystal structure of di(histidino)zinc pentahydrate, Zn(CsHsN30~)2.5H~O, has been determined by Fourier analysis and least-squares refinement using three-dimensional intensity data from CuKa radiation. The crystals are monoclinic, with space group C2/c, and cell dimensions a = 16.41, b = 14.755, c = 10.99 A, ~ = 129.6 °.The primary co-ordination around the zinc atoms, which lie on two-fold axes, is a distorted tetrahedron, consisting of an amino nitrogen and an imidazole nitrogen (at 2.05 and 2.00 A) from each of the two histidine groups. One oxygen atom from each histidine group is also very weakly associated (at 2.91 A). The molecules of di(histidino)zinc and the water molecules take part in an elaborate system of hydrogen bonds holding the structure together.Xext X (1-4-k~ ~/(sin 0') -~-K) Xco~t × (1--k~l/(sin 03+ K) # is one constant for all the data (=0.67 here), K are normalising constants in each layer, to make the correction zero at 0 = 90 °.After this spot-shape correction, all the data were correlated and assembled. The intensities of 1370 reflections were measured, those of 557 were too small for observation, and about 300 were not recorded on any film, although they are within the Cu K~ limit. An approximate scale and temperature factor were determined from a 'Wilson plot'.Sharpened Patterson projections along the b and c axes gave tentative positions for the zinc atoms, which were confirmed by the three-dimensional Patterson synthesis, sharpened 'to point atoms at rest'. The zinc atoms are on two-fold axes at 0, y, ¼, 0, -y, ~, etc., with y= 0.037. By superposltion of the Patterson sections from these two positions as origins, the positions of all atoms of the histidine residue (except hydrogen) were found (Fig. 2). From the smaller peaks three reasonable water-molecule oxygen positions were found, one being on a two-fold axis. The only other features in the superposition map were diffraction peaks around the zinc atom, and one small peak too near to other atomic positions to be a water molecule. Structure factors were calculated and gave R=ZIIFoI-IFd[/XIFo]=21%, for all observed re->0 .-,

ObjectiveAs part of the STAR Programme, a comprehensive study exploring long-term pain after surgery, we investigated how pain and function, health-related quality of life (HRQL), and healthcare resource use evolved over 5 years after total knee replacement (TKR) for those with and without chronic pain 1 year after their primary surgery.MethodsWe used data from the Clinical Outcomes in Arthroplasty Study prospective cohort study, which followed patients undergoing TKR from two English hospitals for 5 years. Chronic pain was defined using the Oxford Knee Score Pain Subscale (OKS-PS) where participants reporting a score of 14 or lower were classified as having chronic pain 1-year postsurgery. Pain and function were measured with the OKS, HRQL using the EuroQoL-5 Dimension, resource use from yearly questionnaires, and costs estimated from a healthcare system perspective. We analysed the changes in OKS-PS, HRQL and resource use over a 5-year follow-up period. Multiple imputation accounted for missing data.ResultsChronic pain was reported in 70/552 operated knees (12.7%) 1 year after surgery. The chronic pain group had worse pain, function and HRQL presurgery and postsurgery than the non-chronic pain group. Those without chronic pain markedly improved right after surgery, then plateaued. Those with chronic pain improved slowly but steadily. Participants with chronic pain reported greater healthcare resource use and costs than those without, especially 1 year after surgery, and mostly from hospital readmissions. 64.7% of those in chronic pain recovered during the following 4 years, while 30.9% fluctuated in and out of chronic pain.ConclusionAlthough TKR is often highly beneficial, some patients experienced chronic pain postsurgery. Although many fluctuated in their pain levels and most recovered over time, identifying people most likely to have chronic pain and supporting their recovery would benefit patients and healthcare systems.

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