The effect of pancreas transplantation on peripheral vascular disease complications.

BACKGROUND: We sought to determine whether pancreas transplantation reduced the incidence of peripheral vascular complications in diabetics with renal insufficiency. METHODS: A retrospective single-center review was done of 36 kidney-pancreas (KP) and 88 kidney-alone (KA) recipients with a diagnosis of diabetes and end-stage renal disease (ESRD) transplanted between May 1997 and July 2002. Risk factors studied included type of transplant, age, gender, history of smoking, coronary artery disease, hypertension, and peripheral vascular disease (PVD). The endpoint was first peripheral vascular event occurring after transplantation, defined as either an amputation or revascularization procedure. RESULTS: The mean age of the cohort was 51 +/- 9 years, 64% of patients were of male gender, 20% with a history of smoking, 98% with hypertension, 15% with coronary artery disease (CAD), and 12% with a history of PVD. With a median follow-up of 45 months (12 to 79 months), 3/36 (8%) of KP recipients suffered a PVD complication, compared to 10/88 (11%) of KA recipients (P = NS). Similarly, age, gender, a past history of smoking, CAD, and hypertension were not predictive of PVD complications. Five of 15 patients (33%) with a pretransplant history of PVD suffered a postoperative PVD event compared to only 8 of 109 patients (7%) with no prior history of PVD (P =.008). CONCLUSIONS: Restoration of normoglycemia by pancreas transplantation did not reduce the risk of PVD complications in diabetics with renal failure. A pretransplant history of PVD was the only risk factor associated with posttransplant PVD events.

Crystallization and preliminary crystallographic analysis of SMase I, a sphingomyelinase from Loxosceles laeta spider venom.

SMase I, a 32 kDa sphingomyelinase found in Loxosceles laeta venom, is responsible for the major pathological effects of spider envenomation. This toxin has been cloned and functionally expressed as a fusion protein containing a 6 x His tag at its N-terminus to yield a 33 kDa protein [Fernandes-Pedrosa et al. (2002), Biochem. Biophys. Res. Commun. 298, 638-645]. The recombinant protein possesses all the biological properties ascribed to the whole L. laeta venom, including dermonecrotic and complement-dependent haemolytic activities. Dynamic light-scattering experiments conducted at 291 K demonstrate that the sample possesses a monomodal distribution, with a hydrodynamic radius of 3.57 nm. L. laeta SMase I was crystallized by the hanging-drop vapour-diffusion technique using the sparse-matrix method. Single crystals were obtained using a buffer solution consisting of 0.08 M HEPES and 0.9 M trisodium citrate, which was titrated to pH 7.5 using 0.25 M sodium hydroxide. Complete three-dimensional diffraction data were collected to 1.8 angstroms at the Laboratório Nacional de Luz Síncrotron (LNLS, Campinas, Brazil). The crystals belong to the hexagonal system (space group P6(1) or P6(5)), with unit-cell parameters a = b = 140.6, c = 113.6 angstroms. A search for heavy-atom derivatives has been initiated and elucidation of the crystal structure is currently in progress.

Crystal structure of the platelet activator convulxin, a disulfide-linked alpha4beta4 cyclic tetramer from the venom of Crotalus durissus terrificus.

Convulxin (CVX), a C-type lectin, isolated from the venom of the South American rattlesnake Crotalus durissus terrificus, causes cardiovascular and respiratory disturbances and is a potent platelet activator which binds to platelet glycoprotein GPVI. The structure of CVX has been solved at 2.4A resolution to a crystallographic residual of 18.6% (R(free)=26.4%). CVX is a disulfide linked heterodimer consisting of homologous alpha and beta chains. The heterodimers are additionally linked by disulfide bridges to form cyclic alpha(4)beta(4)heterotetramers. These domains exhibit significant homology to the carbohydrate-binding domains of C-type lectins, to the factor IX-binding protein (IX-bp), and to flavocetin-A (Fl-A) but sequence and structural differences are observed in both the domains in the putative Ca(2+)and carbohydrate binding regions.

Initial structural analysis of an alpha4beta4 C-type lectin from the venom of Crotalus durissus terrificus.

Convulxin, an alphabeta C-type lectin, is a potent platelet activator isolated from the venom of the South American rattlesnake Crotalus durissus terrificus. It is a 26.5 kDa alphabeta heterodimer consisting of two homologous disulfide-linked chains. The crystals belong to space group I4, with unit-cell parameters a = b = 131.61, c = 121.85 A, and diffraction data were collected to 2.7 A. The structure was solved by molecular replacement and the asymmetric unit contains two alphabeta heterodimers, each of which forms a disulfide-linked cyclic alpha(4)beta(4) tetramer in the unit cell. These alpha(4)beta(4) tetramers are stacked to form a large solvent channel.