997 resultados para Cystatin C


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Im Rahmen dieser Arbeit ist es gelungen, ein besseres Verständnis der beiden Metalloproteasen Meprin α und β in ihrem proteolytischen Netzwerk hinsichtlich ihrer physiologischen Regulation durch endogene Inhibitoren, wie auch der biologischen Funktion von Meprin α für den Prozess der Angiogenese, zu erlangen. rnMit der Analyse des ersten identifizierten endogenen Meprin-Inhibitors Fetuin-A gelang die Bestimmung der Ki-Werte für Meprin α mit 4,2 x 10-5 M und 1,1 x 10-6 M für Meprin β. Des Weiteren konnte für Meprin β eine Schnittstelle im Fetuin-A validiert werden. Mit der Identifizierung von Cystatin C, einem Cystein-Protease-Inhibitor als endogener Inhibitor der Metalloprotease Meprin α, mit einem Ki-Wert von 8,5 x 10-6 M, wurden erstmals Proteasefamilie-übergreifende Inhibitionsmechanismen für Metalloproteasen offenbart.rnDie Analyse von drei potentiellen Meprin-Inhibitoren, identifiziert als Substrate in einem neuen Proteomics-Analyse-Verfahren terminal amine isotopic labeling of substrates (TAILS), ermöglichte die Charakterisierung von Elafin als spezifischen Meprin α-Inhibitor. Für Elafin ist es außerdem gelungen, die durch TAILS ermittelte Schnittstelle für Meprin α mittels Edman Sequenzierung zu validieren. Der secretory leukocyte peptidase inhibitor (SLPI), ein Elafin-Homolog, konnte als weiteres Meprin α-Substrat bestätigt werden. Außerdem gelang es, die Meprin α-Schnittstelle im SLPI zu validieren.rnEin weiteres Ziel dieser Arbeit war, ein besseres Verständnis der biologischen Funktion der Metalloprotease Meprin α zu erlangen. Hier konnte in vivo eine stark pro-angiogene Wirkung von Meprin α gezeigt werden und erstmals die Expression von Meprin α, jedoch nicht von Meprin β, in Endothelzellen nachgewiesen werden. Zugleich konnte mit der Analyse der durch die TAILS-Methode identifizierten pro-angiogenen Substrate vascular endothelial growth factor A (VEGF-A) und connective tissue growth factor (CTGF) der Regulationsmechanismus von Meprin α in der Angiogenese identifiziert werden. So ist Meprin α durch die Spaltung von CTGF in der Lage VEGF-A – gebunden und inhibiert im Komplex mit CTGF – durch proteolytische Spaltung von CTGF wieder freizusetzen. Somit wird die inhibierte VEGF-A-Aktivität wieder vollständig hergestellt. rnMit der Charakterisierung der ersten endogenen Meprin-Inhibitoren ist es gelungen, zu einem besseren Verständnis der endogenen Regulation der Meprine beizutragen und eine Proteasefamilie-übergreifende endogene Regulation aufzuzeigen. Mit der Entdeckung von Meprin α als pro-angiogene Protease und der Entschlüsselung des angiogenen Regulationsmechanismus konnte eine essentielle biologische Bedeutung dieser Protease beschrieben werden.rn

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Obiettivi: valutare in pazienti con rene singolo congenito la correlazione tra il filtrato glomerulare misurato con il DTPA (DTPA-VFG) e 1) marker laboratoristici di danno renale (creatinina, cistatinaC, proteinuria) 2) formule per stimare il filtrato glomerulare 3) parametri di valutazione della crescita renale ecografica. Materiali e metodi: Sono stati arruolati 118 pazienti con rene singolo congenito tra 0 e 18 anni. Sono stati valutati a ogni visita altezza, creatinina, cistatinaC, proteinuria e lunghezza ecografica renale. E’ stato calcolato il filtrato stimato con formule basate sulla creatinina (Schwartz), sulla cistatina C (Zappitelli, Filler, Grubb e Bokenkamp) e su entrambe (equazione di Zappitelli). La crescita renale è stata valutata come rapporto lunghezza ecografica/altezza corporea (USL/H), differenza percentuale tra lunghezza renale misurata e attesa per età (delta%) e presenza o meno d’ipertrofia compensatoria. In 74 bambini è stata misurata la DTPA-VFG. Risultati: Il follow-up è di 2.1 ± 0.9 anni. Il 65% sono maschi. Nessun paziente ha sviluppato danno renale cronico. La media del DTPA-VFG era di 135±44ml/min/1.73m², il valore medio della creatinina 0.47±0.17mg/dl e di cistatinaC di 1±0.4mg/L. La lunghezza ecografica renale media era di 100±17 mm, il rapporto USL/H medio di 0.8±0,1 e il delta% di 1,13±11,4, il 66% presentava ipertrofia renale. Le uniche correlazioni significative con DTPA-VFG sono inversa con la creatinina (p=<.001) e lineare con USL/H (p=<.001). Discussione: Lo studio ha mostrato che come per altre nefrouropatie, la creatina e l’ecografia renale siano due strumenti validi per il follow-up dei pazienti con rene singolo congenito. Il limite principale è dovuto al fatto che nessuno dei pazienti ha sviluppato danno renale cronico e pertanto non è stato possibile stabilire dei cutt-off di rischio per parametri quali USL/H.

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Monitoring of renal function becomes increasingly important in the aging population of HIV-1 infected patients. We compared Cockroft & Gault (C&G), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Modification of Diet in Renal Disease (MDRD), Cystatin C- and 24 h urine-based estimated GFR (eGFR) with the gold standard, measured GFR (mGFR) using [125I]-iothalamate.

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BACKGROUND: Persistent hyperparathyroidism after renal transplantation affects bone and allografts. Cinacalcet, a calcimimetic, reduces serum calcium and PTH in renal transplant recipients with persistent hyperparathyroidism. Here, we address the question whether this effect of cinacalcet persists after withdrawal. METHODS: Therefore, cinacalcet was stopped after 12 months treatment in 10 stable renal transplant patients. Serum calcium, phosphate, PTH, creatinine and cystatin C were monitored for 3 months. RESULTS: Serum calcium, normalized in nine patients before cessation of cinacalcet (2.32 +/- 0.05mmol/l, mean +/- SEM), increased after 3 months of discontinuation by 0.17 +/- 0.04mmol/l, P < 0.05, but remained within the normal range in eight patients. Compared with the time point of cessation, PTH remained unchanged or decreased further after 3 months without therapy in six patients. Measurements of cystatin C suggested an improvement of the glomerular filtration rate after cessation in 9 out of 10 patients (1.55 +/- 0.09 vs 1.33 +/- 0.12 mg/l, P < 0.01). CONCLUSION: First, a beneficial effect of cinacalcet beyond the duration of a 12-month therapy appears to be present in some patients and second, the previously suspected influence of cinacalcet therapy on renal function is reversible. Thus, it is reasonable to consider a trial of cinacalcet cessation to identify these patients. The optimal time point for such a discontinuation is unknown. The present observations are preliminary. They clearly require a prospective randomized trial for definitive confirmation.

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AIM: Acute mountain sickness (AMS) can result in pulmonary and cerebral oedema with overperfusion of microvascular beds, elevated hydrostatic capillary pressure, capillary leakage and consequent oedema as pathogenetic mechanisms. Data on changes in glomerular filtration rate (GFR) at altitudes above 5000 m are very limited. METHODS: Thirty-four healthy mountaineers, who were randomized to two acclimatization protocols, undertook an expedition on Muztagh Ata Mountain (7549 m) in China. Tests were performed at five altitudes: Zurich pre-expedition (PE, 450 m), base camp (BC, 4497 m), Camp 1 (C1, 5533 m), Camp 2 (C2, 6265 m) and Camp 3 (C3, 6865 m). Cystatin C- and creatinine-based (Mayo Clinic quadratic equation) GFR estimates (eGFR) were assessed together with Lake Louise AMS score and other tests. RESULTS: eGFR significantly decreased from PE to BC (P < 0.01). However, when analysing at changes between BC and C3, only cystatin C-based estimates indicated a significant decrease in GFR (P = 0.02). There was a linear decrease in eGFR from PE to C3, with a decrease of approx. 3.1 mL min(-1) 1.73 m(-2) per 1000 m increase in altitude. No differences between eGFR of the two groups with different acclimatization protocols could be observed. There was a significant association between eGFR and haematocrit (P = 0.01), whereas no significant association between eGFR and aldosterone, renin and brain natriuretic peptide could be observed. Finally, higher AMS scores were significantly associated with higher eGFR (P = 0.01). CONCLUSIONS: Renal function declines when ascending from low to high altitude. Cystatin C-based eGFR decreases during ascent in high altitude expedition but increases with AMS scores. For individuals with eGFR <40 mL min(-1) 1.73 m(-2), caution may be necessary when planning trips to high altitude above 4500 m above sea level.

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The in vivo roles of meprin metalloproteases in pathophysiological conditions remain elusive. Substrates define protease roles. Therefore, to identify natural substrates for human meprin α and β we employed TAILS (terminal amine isotopic labeling of substrates), a proteomics approach that enriches for N-terminal peptides of proteins and cleavage fragments. Of the 151 new extracellular substrates we identified, it was notable that ADAM10 (a disintegrin and metalloprotease domain-containing protein 10)-the constitutive α-secretase-is activated by meprin β through cleavage of the propeptide. To validate this cleavage event, we expressed recombinant proADAM10 and after preincubation with meprin β, this resulted in significantly elevated ADAM10 activity. Cellular expression in murine primary fibroblasts confirmed activation. Other novel substrates including extracellular matrix proteins, growth factors and inhibitors were validated by western analyses and enzyme activity assays with Edman sequencing confirming the exact cleavage sites identified by TAILS. Cleavages in vivo were confirmed by comparing wild-type and meprin(-/-) mice. Our finding of cystatin C, elafin and fetuin-A as substrates and natural inhibitors for meprins reveal new mechanisms in the regulation of protease activity important for understanding pathophysiological processes.

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BACKGROUND β2-microglobulin has been increasingly investigated as a diagnostic marker of kidney function and a prognostic marker of adverse outcomes. To date, non-renal determinants of β2-microglobulin levels have not been well described. Non-renal determinants are important for the interpretation and appraisal of the diagnostic and prognostic value of any endogenous kidney function marker. METHODS This cross-sectional analysis was performed within the framework of the www.seniorlabor.ch study, which includes subjectively healthy individuals aged ≥ 60 years. Factors known or suspected to have a non-renal association with kidney function markers were investigated for a non-renal association with serum β2-microglobulin. As a marker of kidney function, the Berlin Initiative Study equation 2 for the estimation of the estimated glomerular filtration rate (eGFR(BIS2)) in the elderly was employed. RESULTS A total of 1302 participants (714 females and 588 males) were enrolled in the study. The use of a multivariate regression model adjusting for age, gender and kidney function (eGFR(BIS2)) revealed age, male gender, and C-reactive protein level to be positively associated with β2-microglobulin levels. In addition, there was an inverse non-renal relationship between systolic blood pressure, total cholesterol and current smoking status. No association with markers of diabetes mellitus, body stature, nutritional risk, thyroid function or calcium and phosphate levels was observed. CONCLUSIONS Serum β2-microglobulin levels in elderly subjects are related to several non-renal factors. These non-renal factors are not congruent to those known from other markers (i.e. cystatin C and creatinine) and remind of classical cardiovascular risk factors.

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In the general population, HDL cholesterol (HDL-C) is associated with reduced cardiovascular events. However, recent experimental data suggest that the vascular effects of HDL can be heterogeneous. We examined the association of HDL-C with all-cause and cardiovascular mortality in the Ludwigshafen Risk and Cardiovascular Health study comprising 3307 patients undergoing coronary angiography. Patients were followed for a median of 9.9 years. Estimated GFR (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration eGFR creatinine-cystatin C (eGFRcreat-cys) equation. The effect of increasing HDL-C serum levels was assessed using Cox proportional hazard models. In participants with normal kidney function (eGFR>90 ml/min per 1.73 m(2)), higher HDL-C was associated with reduced risk of all-cause and cardiovascular mortality and coronary artery disease severity (hazard ratio [HR], 0.51, 95% confidence interval [95% CI], 0.26-0.92 [P=0.03]; HR, 0.30, 95% CI, 0.13-0.73 [P=0.01]). Conversely, in patients with mild (eGFR=60-89 ml/min per 1.73 m(2)) and more advanced reduced kidney function (eGFR<60 ml/min per 1.73 m(2)), higher HDL-C did not associate with lower risk for mortality (eGFR=60-89 ml/min per 1.73 m(2): HR, 0.68, 95% CI, 0.45-1.04 [P=0.07]; HR, 0.84, 95% CI, 0.50-1.40 [P=0.50]; eGFR<60 ml/min per 1.73 m(2): HR, 1.18, 95% CI, 0.60-1.81 [P=0.88]; HR, 0.82, 95% CI, 0.40-1.69 [P=0.60]). Moreover, Cox regression analyses revealed interaction between HDL-C and eGFR in predicting all-cause and cardiovascular mortality (P=0.04 and P=0.02, respectively). We confirmed a lack of association between higher HDL-C and lower mortality in an independent cohort of patients with definite CKD (P=0.63). In summary, higher HDL-C levels did not associate with reduced mortality risk and coronary artery disease severity in patients with reduced kidney function. Indeed, abnormal HDL function might confound the outcome of HDL-targeted therapies in these patients.

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OBJECTIVE Algorithms to predict the future long-term risk of patients with stable coronary artery disease (CAD) are rare. The VIenna and Ludwigshafen CAD (VILCAD) risk score was one of the first scores specifically tailored for this clinically important patient population. The aim of this study was to refine risk prediction in stable CAD creating a new prediction model encompassing various pathophysiological pathways. Therefore, we assessed the predictive power of 135 novel biomarkers for long-term mortality in patients with stable CAD. DESIGN, SETTING AND SUBJECTS We included 1275 patients with stable CAD from the LUdwigshafen RIsk and Cardiovascular health study with a median follow-up of 9.8 years to investigate whether the predictive power of the VILCAD score could be improved by the addition of novel biomarkers. Additional biomarkers were selected in a bootstrapping procedure based on Cox regression to determine the most informative predictors of mortality. RESULTS The final multivariable model encompassed nine clinical and biochemical markers: age, sex, left ventricular ejection fraction (LVEF), heart rate, N-terminal pro-brain natriuretic peptide, cystatin C, renin, 25OH-vitamin D3 and haemoglobin A1c. The extended VILCAD biomarker score achieved a significantly improved C-statistic (0.78 vs. 0.73; P = 0.035) and net reclassification index (14.9%; P < 0.001) compared to the original VILCAD score. Omitting LVEF, which might not be readily measureable in clinical practice, slightly reduced the accuracy of the new BIO-VILCAD score but still significantly improved risk classification (net reclassification improvement 12.5%; P < 0.001). CONCLUSION The VILCAD biomarker score based on routine parameters complemented by novel biomarkers outperforms previous risk algorithms and allows more accurate classification of patients with stable CAD, enabling physicians to choose more personalized treatment regimens for their patients.