Femtosecond photoswitching dynamics and microsecond thermal conversion driven by laser heating in FeIII spin-crossover solids.

International audienceIn this paper we review time-resolved studies of ultrafast light-induced spin-state switching, triggered by a femtosecond laser flash,and the following out-of-equilibrium dynamics in FeIII spincrossover crystals. The out-of-equilibrium dynamics involves several steps, resulting fromthe ultrafast molecular photoswitchingof low-spin (LS) to high-spin (HS) states in solids. First, the transient HS state is reached within 200 femtoseconds, and mayrapidly decayinto the stable LS state of the system. A second process at longer delay,associated with volume expansion, drives additional conversion to the HS state during the so-called elastic step occurring at nanosecond time scale. Finally,the laser heating process induces a temperature jump in the crystal that may result in a significant thermal population of the HS state on microsecond time scale. The photoswitching mechanism is of local nature and has linear dependenceon the excitation fluence, whereas the heating effect can macroscopically perturb the LS/HS equilibrium. We discuss similarities and differences between photoswitching dynamics in solution and in different crystals for which the thermal spin conversion is of more or less pronounced cooperative nature

Dynamic response of the spin-crossover solid Co(H-2(fsa)2 en)(py)(2) to a pulsed magnetic field

International audienceThe spin transition between the paramagnetic high-spin (HS) and low-spin (LS) electronic states of CoII(H2(fsa)2en)(py)2, [H2(fsa)2en=N,N′-ethylene bis(3-carboxysalicylaldimine), py=pyridine] under a pulsed and intense magnetic field (32 T) has been probed by optical reflectivity. In the absence of perturbation, a thermal hysteresis loop (ΔT=19.4K,T1/2=126K) was detected. Applying a magnetic field of 32 T to the solid, the initial state of which belongs to the ascending branch of the hysteresis loop, leads to an irreversible and quasicomplete S=1/→2S=3/2 transition. The experimental evidence of this crossover triggered by a pulsed magnetic field is reported here in conjunction with an adequate Ising-like model. This two-level model, used as a first approach, allows us to reproduce quantitatively the -4.9 K shift in transition temperature under the effect of the 32 T static magnetic field. The dynamic aspects of the previous model are also explored, leading to a description of the main features of the phenomenon. Indeed, an irreversible (reversible) jump of the high-spin fraction is predicted when the pulsed magnetic field is applied in the metastable LS (HS) phase

Multiscale spin-crossover photo-switching dynamics in [(TPA)Fe(III)(TCC)]XF6 derivatives studied by ultrafast optical spectroscopy and time-resolved x-ray diffraction

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Observation of the structural and optical multiscale dynamics in a spin-crossover crystals

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12-month Follow-up Analysis Of A Multicenter, Randomized, Prospective Trial In De Novo Liver Transplantation Recipients (lis2t) Comparing Cyclosporine Microemulsion (c2 Monitoring) And Tacrolimus

The LIS2T study was an open-label, multicenter study in which recipients of a primary liver transplant were randomized to cyclosporine microemulsion (CsA-ME) (Neural) (n = 250) (monitoring of blood concentration at 2 hours postdose) C2 or tacrolimus (n = 245) (monitoring of trough drug blood level[predose])Co to compare efficacy and safety at 3 and 6 months and to evaluate patient status at 12 months. All patients received steroids with or without azathioprine. At 12 months, 85% of CsA-ME patients and 86% o tacrolimus patients survived with a functioning grat (P not significant). Efficacy was similar in deceased-and living-donor recipients. Significantly fewer hepatitis C-positive patients died or lost their graft by 12 months with CsA-ME 95/ 88,6%) than with tacrolimus (14/85,16%) (P< 0.03). Recurrence of hepatitis C virus in liver grafts was similar in each group. Based on biopsies driven by clinical events, the mean time to histological diagnosis of hepatitis C virus recurrence was significantly longer with CsA-ME (100 ± 50 days) than with tacrolimus (70 ± 40 days) (P < 0.05). Median serum creatinine at 12 months was 106 μmol/L with CsA-ME and with tacrolimus. More patients who were nondiabetic at baseline received antihyperglycemic therapy in the tacrolimus group at 12 months was (13% vs. 5%, P< 0.01). Of patients who were diabetic at baseline, more tacrolimus-treated individuals required anti-diabetic treatment at 12 months ( 70% vs. 49%, P+ 0.02). Treatment for de novo or preexisting hypertension or hyperlipidemia was similar in both groups. In conclusion, the efficacy of CsA-ME monitored by blood concentration at 2 hours postdose and tacrolimus in liver transplant patients is equivalent to 12 months, and renal function is similar. More patients required antidiabetic therapy with tacrolimus regardless of diabetic status at baseline. © 2006 AASLD.121014641472United Network for Organ Sharing Data Report: Liver Kaplan-Meier Graft Survival Rates for Transplants Performed 1996-2001 (2004), http://www.optn.org, Available at: Accessed: February 2Vogt, D.P., Henderson, J.M., Carey, W.D., Barnes, D., The long-term survival and causes of death in patients who survive at least 1 year after liver transplantation (2002) Surgery, 132, pp. 775-780Johnston, S.D., Morris, J.K., Cramb, R., Gunson, B.K., Neuberger, J., Cardiovascular morbidity and mortality after orthotopic liver transplantation (2002) Transplantation, 73, pp. 901-906Neal, D.A., Tom, B.D., Luan, J., Wareham, N.J., Gimson, A.E., Delrivere, L.D., Is there disparity between risk and incidence of cardiovascular disease after liver transplant? (2004) Transplantation, 77, pp. 93-99O'Grady, J.G., Burroughs, Hardy, P., Elbourne, D., Truesdale, A., Tacrolimus versus microemulsified ciclosporin in liver transplantation: The TMC randomised controlled trial (2002) Lancet, 360, pp. 1119-1125Mühlbacher, F., Tacrolimus versus cyclosporin microemulsion in liver transplantation: Results of a 3-month study (2001) Transplant Proc, 33, pp. 1339-1340. , European Liver Transplantation Tacrolimus vs Cyclosporin Microemulsion Study GroupLevy, G., Villamil, F., Samuel, D., Sanjuan, F., Grazi, G.L., Wu, Y., Results of LIS2T, a multicenter, randomized study comparing cyclosporine microemulsion with C2 monitoring and tacrolimus with Co monitoring in de novo liver transplantation (2004) Transplantation, 77, pp. 1632-1638Levy, G., Burra, P., Cavallari, A., Duvoux, C., Lake, J., Mayer, A.D., Improved clinical outcomes for liver transplant recipients using cyclosporine monitoring based on 2-hr post-dose levels (C2) (2002) Transplantation, 73, pp. 953-959Villamil, F., Pollard, S., C2 monitoring of cyclosporine in de novo liver transplant recipients: The clinician's perspective (2004) Liver Transpl, 10, pp. 577-583Yantorno, S.E., Varela, E.B., Raffa, S.R., Descalzi, V.I., Gomez Carretero, M.L., Pirola, D.A., How common is delayed cyclosporine absorption following liver transplantation? (2005) Liver TranspI, 11, pp. 167-173Watashi, K., Hijakata, M., Hosaka, M., Yamaji, M., Shimotohno, K., Cyclosporin A suppresses replication of hepatitis C virus genome in cultured hepatocytes (2003) Hepatology, 38, pp. 1282-1288Nakagawa, M., Sakamoto, N., Enomoto, N., Tanabe, Y., Kanazawa, N., Koyama, T., Specific inhibition of hepatitis C virus replication by cyclosporin A (2004) Biochem Biophys Res Commun, 313, pp. 42-47Manir̀e, T., Ethier, C., Raymond, V.A., Andre, A., Bilodeau, M., Evaluation of the effect of immunosuppressive agents on hepatitis C: Cyclosporine reduces viral replication in the replicon model (2004) Transplantation, 78 (SUPPL. 1), pp. 13-14. , [abstract]Sheiner, P.A., Schwartz, M.E., Mor, E., Schulager, L.K., Theise, N., Kishikawa, K., Severe or multiple rejection episodes are associated with early recurrence of hepatitis C after orthotopic liver transplantation (1995) Hepatology, 21, pp. 30-34Johnson, M.W., Washburn, W.K., Freeman, R.B., Fitzmaurice, S.E., Dienstag, J., Basgoz, N., Hepatitis C viral infection in liver transplantation (1996) Arch Surg, 131, pp. 284-291Paik, S.W., Tan, H.P., Klein, A.S., Boitnott, J.K., Thulavath, P.J., Outcome of orthotopic liver transplantation in patients with hepatitis C (2002) Dig Dis Sci, 47, pp. 450-455Duvoux, C., Mennecier, D., Pageaux, G., Conti, F., Roudot-Thoraval, F., Dhumeaux, D., Immunosuppression with tacrolimus an absence of antihypertensive therapy are associated with fibrosis progression after hepatitis C virus (HCV) graft reinfection (2002) Transplantation, 74 (SUPPL.). , International Society of Transplantation Congress 2002 [abstract 2652]Hunt, J., Gordon, F.D., Lewis, W.D., Histological recurrence and progression of hepatitis C after orthotopic liver transplantation: Influence of immunosuppressive regimens (2001) Liver Transpl, 7, pp. 1056-1063Berenguer, M., Prieto, M., San Juan, F., Rayon, J.M., Martinez, F., Carrasco, D., Contribution of donor age to the recent decrease in patient survival among HCV-infected liver transplant recipients (2002) Hepatology, 36, pp. 202-210Ghobrial, R.M., Farmer, D.G., Baquerizo, A., Orthotopic liver transplantation for hepatitis C: Outcome, effect of immunosuppression, and causes of retransplantation duringan 8-year single-center experience (1999) Ann Surg, 6, pp. 824-833Neumann, U.P., Berg, T., Bahra, M., Puhl, G., Guckelberger, O., Langrehr, J.M., Long-term outcome of liver transplants for chronic hepatitis C: A 10-year follow-up (2004) Transplantation, 77, pp. 226-231Ericzon, B., Groth, C., Bismuth, H., Calne, R., McMaster, P., Neuhaus, P., Glucose metabolism in liver transplant recipients treated with FK 506 or cyclosporin in the European multicentre study (1994) Transplant Int, 7 (SUPPL.), pp. Sll-S14Lohmann, T., List, C., Lamesch, P., Kohlhaw, K., Wenzke, M., Schwarz, C., Diabetes mellitus and islet cell specific autoimmunity as adverse effects of immunosuppressive therapy by FK506/tacrolimus (2000) Exp Clin Endocrinol Diabetes, 108, pp. 347-352Prasad, G.V., Kim, S.J., Huang, M., Kohlhaw, K., Zaltzman, J.S., Fenton, S.S., Reduced incidence of new-onset diabetes mellitus after renal transplantation with 3-hydroxy-3-methylglutaryl-coenzyme a reductase inhibitors (statins) (2004) Am J Transplant, 4, pp. 1897-190