High-Resolution HLA-DRB1 Allele Frequencies in a Romanian Cohort of Stem Cell Donors.

The goal of the current study was to determine the high-resolution frequencies of the HLA-DRB1 alleles among the analyzed Romanian cohort of healthy stem cell donors. Using Next Generation Sequencing (NGS), we estimated class II HLA-DRB1 allele frequencies to a 6-digit resolution through HLA typing in a Romanian cohort of healthy individuals. The study for HLA genotyping included 420 willing donors from the National Registry of Voluntary Hematopoietic Stem Cell Donors (RNDVCSH). In 2020 and 2021, peripheral blood samples were collected and transported to the Fundeni Clinical Institute. We used the Immucor Mia Fora NGS MFlex kit for HLA genotyping. Forty-one different alleles were detected in 420 analyzed samples, out of which the most frequent HLA-DRB1 alleles were DRB1*16:01:01 (12.6%), DRB1*11:04:01 (12.1%) and DRB1*03:01:01 (12%). The HLA-DRB1*11:01:02 and -DRB1*08:04:01, -DRB1*05:01:01, -DRB1*13:05:01, -DRB1*14:07:01, -DRB1*09:01:02, -DRB1*11:02:01, -DRB1*04:07:01, -DRB1*15:03:01, -DRB1*03:02:01, -DRB1*04:06:02, -DRB1*04:08:01, -DRB1*14:05:01 were identified only once. The results revealed similarities with countries belonging to the Eastern Europe, the Balkans and the Caucasus regions. Further studies on larger Romanian cohorts are needed for confirming the current results.

Endovascular renal sympathetic denervation to improve heart failure with reduced ejection fraction: the IMPROVE-HF-I study.

INTRODUCTION: The aim of the present study was to assess the safety and efficacy of renal sympathetic denervation (RDN) in patients with heart failure with reduced ejection fraction (HFrEF). METHODS: We randomly assigned 50 patients with a left ventricular ejection fraction (LVEF) ≤ 35% and NYHA class ≥ II, in a 1:1 ratio, to either RDN and optimal medical therapy (OMT) or OMT alone. The primary safety endpoint was the occurrence of a combined endpoint of cardiovascular death, rehospitalisation for heart failure, and acute kidney injury at 6 months. The primary efficacy endpoint was the change in iodine-123 meta-iodobenzylguanidine (123I­MIBG) heart-to-mediastinum ratio (HMR) at 6 months. RESULTS: Mean age was 60 ± 9 years, 86% was male and mean LVEF was 33 ± 8%. At 6 months, the primary safety endpoint occurred in 8.3% vs 8.0% in the RDN and OMT groups, respectively (p = 0.97). At 6 months, the mean change in late HMR was -0.02 (95% CI: -0.08 to 0.12) in the RDN group, versus -0.02 (95% CI: -0.09 to 0.12) in the OMT group (p = 0.95) whereas the mean change in washout rate was 2.34 (95% CI: -6.35 to 1.67) in the RDN group versus -2.59 (95% CI: -1.61 to 6.79) in the OMT group (p-value 0.09). CONCLUSION: RDN with the Vessix system in patients with HFrEF was safe, but did not result in significant changes in cardiac sympathetic nerve activity at 6 months as measured using 123I­MIBG.

Listing criteria for heart transplantation in the Netherlands.

The updated listing criteria for heart transplantation are presented on behalf of the three heart transplant centres in the Netherlands. Given the shortage of donor hearts, selection of those patients who may expect to have the greatest benefit from a scarce societal resource in terms of life expectancy and quality of life is inevitable. The indication for heart transplantation includes end-stage heart disease not remediable by more conservative measures, accompanied by severe physical limitation while on optimal medical therapy, including ICD/CRT­D. Assessment of this condition requires cardiopulmonary stress testing, prognostic stratification and invasive haemodynamic measurements. Timely referral to a tertiary centre is essential for an optimal outcome. Chronic mechanical circulatory support is being used more and more as an alternative to heart transplantation and to bridge the progressively longer waiting time for heart transplantation and, thus, has become an important treatment option for patients with advanced heart failure.

In search of an efficient strategy to monitor disease status of chronic heart failure outpatients: added value of blood biomarkers to clinical assessment.

INTRODUCTION: Blood biomarkers have the potential to monitor the severity of chronic heart failure (CHF). Studies correlating repeated measurements of blood biomarkers with repeatedly assessed New York Heart Association (NYHA) class over a prolonged follow-up period, and concomitantly investigating their associations with clinical endpoints, have not yet been performed. METHODS: Between 2011-2013, 263 CHF patients were included. At inclusion and subsequently every 3 months, we measured N­terminal pro-B-type natriuretic (NT-proBNP), high-sensitivity troponin T (Hs-TnT) and C­reactive protein (CRP), and assessed NYHA class. The primary endpoint comprised heart failure hospitalisation, cardiovascular mortality, cardiac transplantation or left ventricular assist device implantation. Time-dependent Cox models were used. RESULTS: Mean age was 67 ± 13 years, 72% were men and 27% were in NYHA class III-IV. We obtained 886 repeated measures (median 3 [IQR 2-5] per patient). The primary endpoint was reached in 41 patients during a median follow-up of 1.0 [0.6-1.4] year. Repeatedly measured NT-proBNP and Hs-TnT were significantly associated with repeatedly assessed NYHA class, whereas CRP was not (NT-proBNP: ß [95% CI]: 1.56 [1.17-2.06]ln(ng/l) increase per point increase in NYHA class, p = 0.002; HsTNT: ß [95% CI]: 1.58 [1.21-2.07]). Serially measured NT-proBNP (HR [95% CI]:2.86 [1.73-4.73]), CRP (1.69 [1.21-2.34]) and NYHA class (2.33 [1.51-3.62]) were positively and independently associated with the primary endpoint, whereas Hs-TnT lost statistical significance after multivariable adjustment. A model containing serially measured NYHA class and NT-proBNP displayed a C-index of 0.84, while serially measured NYHA class and CRP showed a C-index of 0.82. CONCLUSION: Temporal NT-proBNP, CRP and NYHA class patterns are independently associated with adverse clinical outcome. Serially measured NT-proBNP and NYHA class are best suited for monitoring CHF outpatients.

The effect of levodopa-carbidopa intestinal gel infusion long-term therapy on motor complications in advanced Parkinson's disease: a multicenter Romanian experience.

Chronic treatment with oral levodopa is associated with an increased frequency of motor complications in the late stages of Parkinson's disease (PD). Continuous administration of levodopa-carbidopa intestinal gel (LCIG-Duodopa(®), Abbott Laboratories), which has been available in Romania since 2009, represents an option for treating patients with advanced PD. Our primary objective was to report changes in motor complications after initiation of LCIG therapy. The secondary objectives were as follows: to determine the impact of LCIG therapy on the daily levodopa dose variation before/and after LCIG, to collect patient self-assessments of quality of life (QoL), and to study the overall tolerability and safety of LCIG administration. A retrospective analysis (2009-2013) of LCIG therapy and the experience in nine neurology centers in Romania was performed. The impact of LCIG therapy was evaluated by analyzing changes in motor fluctuations, dyskinesia and the patients' QoL after initiating therapy. The safety of LCIG therapy was estimated by noting agent-related adverse events (AEs) and medical device-related AEs. In the 113 patients included, we observed a significant improvement in PD symptoms after initiation of LCIG therapy. The "on" period increased, with a mean value of 6.14 h, and the dyskinesia period was reduced, with a mean value of 29.4 %. The quantified non-motor symptoms subsided. The patients exhibited significant improvements in QoL scores. There were few AEs and few cases of LCIG therapy discontinuation. LCIG is an important and available therapeutic option for managing patients with advanced PD.

Cardiac allograft vasculopathy in Dutch heart transplant recipients.

BACKGROUND: Cardiac allograft vasculopathy (CAV) is a multifactorial disease and a major cause of graft failure after heart transplantation. However, the impact of CAV may vary according to the definition and the regional differences in transplantation settings. OBJECTIVES: We sought to assess CAV prevalence, predictors and prognosis in Dutch heart transplant recipients based on coronary angiography, following the 2010 standard nomenclature of the International Society for Heart and Lung Transplantation. METHODS: Patients ≥18 years who underwent heart transplantation at our centre with at least one coronary angiography during follow-up were included in the analysis. Clinical variables were collected prospectively. RESULTS: Among 495 analysed recipients, there were 238 (48 %) with CAV. The prevalence of CAV was 18, 47 and 70 % at 4, 12 and 20 years, respectively. In the multivariable proportional hazards regression analysis, only male donor gender and increasing donor age were significantly associated with the risk of CAV. The long-term prognosis of the patients with CAV at fourth-year angiography was significantly worse as compared with that of CAV-free patients, independently of the severity of CAV (p < 0.001). CONCLUSION: The prevalence of CAV increased gradually over time, with a similar trend as in other registries. Post-transplant survival is decreased in patients with any degree of early CAV, indicating that management strategies should start with donor selection and preventive measures immediately after transplantation.

Haemolysis as a first sign of thromboembolic event and acute pump thrombosis in patients with the continuous-flow left ventricular assist device HeartMate II.

BACKGROUND: Despite advances in pump technology, thromboembolic events/acute pump thrombosis remain potentially life-threatening complications in patients with continuous-flow left ventricular assist devices (CF-LVAD). We sought to determine early signs of thromboembolic event/pump thrombosis in patients with CF-LVAD, which could lead to earlier intervention. METHODS: We analysed all HeartMate II recipients (n = 40) in our centre between December 2006 and July 2013. Thromboembolic event/pump thrombosis was defined as a transient ischaemic attack (TIA), ischaemic cerebrovascular accident (CVA), or pump thrombosis. RESULTS: During median LVAD support of 336 days [IQR: 182-808], 8 (20 %) patients developed a thromboembolic event/pump thrombosis (six TIA/CVA, two pump thromboses). At the time of the thromboembolic event/pump thrombosis, significantly higher pump power was seen compared with the no-thrombosis group (8.2 ± 3.0 vs. 6.4 ± 1.4 W, p = 0.02), as well as a trend towards a lower pulse index (4.1 ± 1.5 vs. 5.0 ± 1.0, p = 0.05) and a trend towards higher pump flow (5.7 ± 1.0 vs. 4.9 ± 1.9 L m, p = 0.06). The thrombosis group had a more than fourfold higher lactate dehydrogenase (LDH) median 1548 [IQR: 754-2379] vs. 363 [IQR: 325-443] U/L, p = 0.0001). Bacterial (n = 4) or viral (n = 1) infection was present in 5 out of 8 patients. LDH > 735 U/L predicted thromboembolic events/pump thrombosis with a positive predictive value of 88 %. CONCLUSIONS: In patients with a CF-LVAD (HeartMate II), thromboembolic events and/or pump thrombosis are associated with symptoms and signs of acute haemolysis as manifested by a high LDH, elevated pump power and decreased pulse index, especially in the context of an infection.

Preventing LVAD implantation by early short-term mechanical support and prolonged inodilator therapy : A case series with acute refractory cardiogenic shock treated with veno-arterial extracorporeal membrane oxygenation and optimised medical strategy.

Cardiogenic shock continues to be a life-threatening condition carrying a high mortality and morbidity, where the prognosis remains poor despite intensive modern treatment modalities. In recent years, mainly technical improvements have led to a more widespread use of short- and long-term mechanical circulatory support, such as veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and left ventricular assist devices (LVADs). Currently, LVADs are indispensable as 'bridge' to cardiac recovery, heart transplantation (HTX), and/or as destination therapy Importantly, both LVADs and HTX put a vast burden on financial resources, besides significant short- and long-term risks of morbidity and mortality. These considerations underscore the importance of optimal timing and appropriate patient selection for LVAD therapy, avoiding as much as possible an unfortunate and costly clinical path. In this report, we present a series of three cases with acute refractory cardiogenic shock ('crash and burn', INTERMACS profile 1) successfully treated by ECMO and early optimal medical therapy preventing a certain path towards LVAD and/or HTX, for which they were initially referred. This conservative approach in INTERMACS profile one patients warrants very early introduction of adequate medical heart failure therapy under the umbrella of a combination of short-term mechanical circulatory and inotropic support by phosphodiesterase inhibitors. Therefore, this novel combined medical-mechanical approach could have important clinical implications for this extremely challenging patient category, as it may avoid an unnecessary and costly clinical path towards LVAD and/or heart transplantation.

Temporal evolution of anxiety and depression in chronic heart failure and its association with clinical outcome.

BACKGROUND: Although anxiety and depression have been associated with adverse outcomes in chronic heart failure (HF), data on temporal evolution of these symptoms are scarce. We aimed to investigate the association between repeatedly measured depression and anxiety symptoms and clinical outcome in chronic HF patients. METHODS: In this prospective observational study, outpatients with chronic HF were included and followed-up for a maximum of 2.5 years. The hospital anxiety and depression scale (HADS) questionnaire was conducted every six months. The primary endpoint was a composite of HF hospitalization, cardiovascular death, heart transplantation and left ventricular assist device (LVAD) implantation. Cox and joint models were used to investigate the association between the HADS score and the endpoint. RESULTS: A total of 362 patients filled out a median (25th-75th percentile) of 3 [2-4] questionnaires each. Mean ± SD age was 63 ± 13 years, 72% were men. Anxiety scores remained relatively stable leading up to the endpoint, while depression scores increased. Higher baseline depression scores were significantly associated with the endpoint (hazard ratio [HR] 1.68 and 95% confidence interval [CI] 1.19-2.36 per log(score+1), p = 0.003), while higher baseline anxiety scores did not reach statistical significance (HR [95% CI] 1.34 [0.99-1.83], p = 0.061). When repeatedly measured, both higher anxiety (HR [95% CI] 1.57[1.07-2.30], p = 0.022) and depression (HR [95% CI] 2.04 [1.39-3.06], p < 0.001) scores were significantly associated with the endpoint. CONCLUSION: Serial measurements of depression and anxiety symptoms identify chronic HF patients with increased risk of adverse clinical outcomes. Screening for both disorders should be considered in clinical practice.

Living donor liver transplantation with dual grafts -- a case report.

BACKGROUND: Living donor liver transplantation (LDLT) exposes to risks both the donor, due to a potential small residual liver volume, and the recipient, who faces the risk of small-for-size graft syndrome. In order to overcome these drawbacks, liver grafts from two different donors can be used. This paper presents a case of dual graft LDLT using a right hemiliver and a left lateral section from related donors. CASE PRESENTATION: A 14-year old female diagnosed with chronic hepatic failure due to Wilson's disease with Model-for-End- Stage-Liver-Disease score of 25, underwent a dual graft LDLT, receiving a right hemiliver with a reconstructed middle hepatic vein from her sister, and a left lateral section from her mother. None of the grafts complied with a satisfactory graft-to-recipient weight ratio (GRWR), if they would have been independently transplanted. The combined GRWR was 1.10. The donors and the recipient have been followed-up for over 1 year. RESULTS: The donors had no postoperative complications. The donors and the recipient were discharged 8 and 19 days after surgery, respectively. After 12-month follow-up, both donors and the recipient were alive, with normal graft function. CONCLUSION: Dual graft LDLT can be a feasible solution to overcome the risk of small-for-size graft syndrome. ABBREVIATIONS: BSA = body surface area, GRWR = graft-to-recipient weight ratio, GV SLV = recipient standard liver volume, HA = hepatic artery, HD = hepatic duct, HV = hepatic vein, LDLT = Living donor liver transplantation, LL = left lobe, LLS = left lateral section, MELD = Model for End-Stage Liver Disease, POD = postoperative day, PV = portal vein, RL = right lobe, SFS = small-for-size graft, SLV = standard liver volume, WD = Wilson's disease.

Nurse Preceptors' Experiences of an Online Strength-Based Nursing Course in Clinical Teaching.

Background: Online educational programs for nurse preceptors have been created based on various theoretical frameworks; however, no programs using a Strengths-Based Nursing (SBN) approach could be located. Purpose: This qualitative descriptive study explored the nurse preceptors' experiences in using a SBN approach to provide clinical teaching to nursing students after completing an online SBN clinical teaching course. Methods: Semi-structured interviews were conducted with six nurses. Data was thematically analyzed. Findings: Although their levels of familiarity with SBN varied, all preceptors acknowledged that using a SBN approach in clinical teaching benefits both students and educators. They reported that it empowered students and that it allowed them to discover their strengths. Getting to know their students helped the preceptors provide tailored learning experiences and feedback. Using the SBN approach simultaneously enhanced the preceptors' self-confidence and created opportunities for shared learning. Conclusion: Using a strengths' approach offers nurse preceptors a powerful tool to facilitate student learning and skills development in clinical practice.

Relationship between physiological measures of excitability and levels of glutamate and GABA in the human motor cortex.

Magnetic resonance spectroscopy (MRS) allows measurement of neurotransmitter concentrations within a region of interest in the brain. Inter-individual variation in MRS-measured GABA levels have been related to variation in task performance in a number of regions. However, it is not clear how MRS-assessed measures of GABA relate to cortical excitability or GABAergic synaptic activity. We therefore performed two studies investigating the relationship between neurotransmitter levels as assessed by MRS and transcranial magnetic stimulation (TMS) measures of cortical excitability and GABA synaptic activity in the primary motor cortex. We present uncorrected correlations, where the P value should therefore be considered with caution. We demonstrated a correlation between cortical excitability, as assessed by the slope of the TMS input-output curve and MRS-assessed glutamate levels (r = 0.803, P = 0.015) but no clear relationship between MRS-assessed GABA levels and TMS-assessed synaptic GABA(A) activity (2.5 ms inter-stimulus interval (ISI) short-interval intracortical inhibition (SICI); Experiment 1: r = 0.33, P = 0.31; Experiment 2: r = -0.23, P = 0.46) or GABA(B) activity (long-interval intracortical inhibition (LICI); Experiment 1: r = -0.47, P = 0.51; Experiment 2: r = 0.23, P = 0.47). We demonstrated a significant correlation between MRS-assessed GABA levels and an inhibitory TMS protocol (1 ms ISI SICI) with distinct physiological underpinnings from the 2.5 ms ISI SICI (r = -0.79, P = 0.018). Interpretation of this finding is challenging as the mechanisms of 1 ms ISI SICI are not well understood, but we speculate that our results support the possibility that 1 ms ISI SICI reflects a distinct GABAergic inhibitory process, possibly that of extrasynaptic GABA tone.

Sex-specific temporal evolution of circulating biomarkers in patients with chronic heart failure with reduced ejection fraction.

BACKGROUND: We aimed to assess differences in clinical characteristics, prognosis, and the temporal evolution of circulating biomarkers in male and female patients with HFrEF. METHODS: We included 250 patients (66 women) with chronic heart failure (CHF) between 2011 and 2013 and performed trimonthly blood sampling during a median follow-up of 2.2 years [median (IQR) of 8 (5-10) urine and 9 (5-10) plasma samples per patient]. After completion of follow-up we measured 8 biomarkers. The primary endpoint (PE) was the composite of cardiac death, cardiac transplantation, left ventricular assist device implantation, and hospitalization due to acute or worsened CHF. Joint models were used to determine whether there were differences in the temporal patterns of the biomarkers between men and women as the PE approached. RESULTS: A total of 66 patients reached the PE of which 52 (78.8%) were male and 14 (21.2%) were female. The temporal patterns of all studied biomarkers were associated with the PE, and overall showed disadvantageous changes as the PE approached. For NT-proBNP, HsTnT, and CRP, women showed higher levels over the entire follow-up duration and concomitant numerically higher hazard ratios [NT-proBNP: women: HR(95%CI) 7.57 (3.17-21.93), men: HR(95%CI) 3.14 (2.09-4.79), p for interaction = 0.104, HsTnT: women: HR(95%CI) 6.38 (2.18-22.46), men: HR(95%CI) 4.91 (2.58-9.39), p for interaction = 0.704, CRP: women: HR(95%CI) 7.48 (3.43-19.53), men: HR(95%CI) 3.29 [2.27-5.44], p for interaction = 0.106). In contrast, temporal patterns of glomerular and tubular renal markers showed similar associations with the PE in men and women. CONCLUSION: Although interaction terms are not statistically significant, the associations of temporal patterns of NT-proBNP, HsTnT, and CRP appear more outspoken in women than in men with HFrEF, whereas associations seem similar for temporal patterns of creatinine, eGFR, Cystatin C, KIM-1 and NAG. Larger studies are needed to confirm these potential sex differences.

Changes in locus-specific V(D)J recombinase activity induced by immunoglobulin gene products during B cell development.

The process of V(D)J recombination is crucial for regulating the development of B cells and for determining their eventual antigen specificity. Here we assess the developmental regulation of the V(D)J recombinase directly, by monitoring the double-stranded DNA breaks produced in the process of V(D)J recombination. This analysis provides a measure of recombinase activity at immunoglobulin heavy and light chain loci across defined developmental stages spanning the process of B cell development. We find that expression of a complete immunoglobulin heavy chain protein is accompanied by a drastic change in the targeting of V(D)J recombinase activity, from being predominantly active at the heavy chain locus in pro-B cells to being exclusively restricted to the light chain loci in pre-B cells. This switch in locus-specific recombinase activity results in allelic exclusion at the immunoglobulin heavy chain locus. Allelic exclusion is maintained by a different mechanism at the light chain locus. We find that immature, but not mature, B cells that already express a functional light chain protein can undergo continued light chain gene rearrangement, by replacement of the original rearrangement on the same allele. Finally, we find that the developmentally regulated targeting of V(D)J recombination is unaffected by enforced rapid transit through the cell cycle induced by an E mu-myc transgene.

Neuronal differentiation and long-term culture of the human neuroblastoma line SH-SY5Y.

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder in industrialized countries. Present cell culture models for PD rely on either primary cells or immortal cell lines, neither of which allow for long-term experiments on a constant population, a crucial requisite for a realistic model of slowly progressing neurodegenerative diseases. We differentiated SH-SY5Y human dopaminergic neuroblastoma cells to a neuronal-like state in a perfusion culture system using a combination of retinoic acid and mitotic inhibitors. The cells could be cultivated for two months without the need for passage. We show, by various means, that the differentiated cells exhibit, at the molecular level, many neuronal properties not characteristic to the starting line. This approach opens the possibility to develop chronic models, in which the effect of perturbations and putative counteracting strategies can be monitored over long periods of time in a quasi-stable cell population.

Disseminated intravascular coagulation and a negative D-dimer test.

The diagnosis of disseminated intravascular coagulation (DIC) requires the presence of a fibrin-related marker. D-dimer is frequently used in clinical practice as a fibrin-related marker. We present a case of paraneoplastic DIC with a false-negative D-dimer test. Repeating the test using a different D-dimer assay as well as the measurement of other fibrinolysis markers confirmed the diagnosis of DIC.

Fatigue of Metallic Stents: From Clinical Evidence to Computational Analysis.

The great success of stents in treating cardiovascular disease is actually undermined by their long-term fatigue failure. The high variability of stent failure incidence suggests that it is due to several correlated aspects, such as loading conditions, material properties, component design, surgical procedure, and patient functional anatomy. Numerical and experimental non-clinical assessments are included in the recommendations and requirements of several regulatory bodies and they are thus exploited in the analysis of stent fatigue performance. Optimization-based simulation methodologies have been developed as well, to improve the fatigue endurance of novel designs. This paper presents a review on the fatigue issue in metallic stents, starting from a description of clinical evidence about stent fracture up to the analysis of computational approaches available from the literature. The reported discussion on both the experimental and numerical framework aims at providing a general insight into stent lifetime prediction as well as at understanding the factors which affect stent fatigue performance for the design of novel components.

Oxidized lipoproteins degrade the endothelial surface layer : implications for platelet-endothelial cell adhesion.

BACKGROUND: Flowing erythrocytes and platelets are separated from the luminal endothelial cell (EC) surface by a 0.5-microm-wide space named the endothelial surface layer. We hypothesized that the disruption of the endothelial surface layer by oxidized low-density lipoproteins (Ox-LDL) contributes to atherogenic increases in vascular wall adhesiveness. METHODS AND RESULTS: The hamster cremaster muscle preparation was used for intravital microscopic observation of the distance between erythrocytes and the capillary EC surface. Moderate Ox-LDL was prepared by exposing native LDL to CuSO(4) for 6 hours. The dimension of the EC surface layer averaged 0.6+/-0.1 microm during control situations, but a bolus intravenous injection of Ox-LDL (0.4 mg/100 g of body weight) transiently diminished the EC surface layer by 60% within 25 minutes, which correlated with a transient increase in the number of platelet-EC adhesions. Combined administration of superoxide dismutase and catalase completely blocked the effect of Ox-LDL on the dimension of the EC surface layer and inhibited platelet-EC adhesion. CONCLUSIONS: Oxygen-derived free radicals mediate the disruption of the EC surface layer and increase vascular wall adhesiveness by Ox-LDL.

High-resolution crystal structure of S. cerevisiae Ypt51(DeltaC15)-GppNHp, a small GTP-binding protein involved in regulation of endocytosis.

Ypt/Rab proteins are membrane-associated small GTP-binding proteins which play a central role in the coordination, activation and regulation of vesicle-mediated transport in eukaryotic cells. We present the 1.5 A high-resolution crystal structure of Ypt51 in its active, GppNHp-bound conformation. Ypt51 is an important regulator involved in the endocytic membrane traffic of Saccharomyces cerevisiae. The structure reveals small but significant structural differences compared with H-Ras p21. The effector loop and the catalytic loop are well defined and stabilized by extensive hydrophobic interactions. The switch I and switch II regions form a well-defined epitope for hypothetical effector protein binding. Sequence comparisons between the different isoforms Ypt51, Ypt52 and Ypt53 provide the first insights into determinants for specific effector binding and for fine-tuning of the intrinsic GTP-hydrolysis rate.