Albumin of People with Diabetes Mellitus Is More Reduced at Low HbA1c.

Oxidative stress is involved in the development, progression, and complications of diabetes mellitus (DM). Oxidative modification of human serum albumin's cysteine-34 is a marker for oxidative stress-related pathological conditions. We aimed to evaluate the redox state of albumin in patients with DM to investigate possible correlations with age, diabetes duration, and disease control status. Plasma aliquots were collected from 52 participants (26 type 1 and 26 type 2 DM). Patients were divided into two groups according to their glycated hemoglobin levels less than or equal to and greater than 58 mmol/L. Albumin redox state was assessed with high-performance liquid chromatography by fractionating it into human mercaptalbumin (HMA) and human nonmercaptalbumin 1 and 2 (HNA1 and HNA2). Albumin redox fractions were differently related to the age of study participants. In age-matched T1DM and T2DM groups, the albumin redox state was essentially the same. Irreversibly oxidized HNA2 was positively correlated with diabetes duration, especially in the T1DM group. HNA was increased in people with an increased HbA1c (>58 mmol/mol). Our results support the hypothesis that oxidative stress plays a crucial role in DM pathogenesis and emphasize the importance of diabetes control on systemic oxidative burden.

Targeting structural flexibility in low density lipoprotein by integrating cryo-electron microscopy and high-speed atomic force microscopy.

Low-density lipoprotein (LDL) plays a crucial role in cholesterol metabolism. Responsible for cholesterol transport from the liver to the organs, LDL accumulation in the arteries is a primary cause of cardiovascular diseases, such as atherosclerosis. This work focuses on the fundamental question of the LDL molecular structure, as well as the topology and molecular motions of apolipoprotein B-100 (apo B-100), which is addressed by single-particle cryo-electron microscopy (cryo-EM) and high-speed atomic force microscopy (HS-AFM). Our results suggest a revised model of the LDL core organization with respect to the cholesterol ester (CE) arrangement. In addition, a high-density region close to the flattened poles could be identified, likely enriched in free cholesterol. The most remarkable new details are two protrusions on the LDL surface, attributed to the protein apo B-100. HS-AFM adds the dimension of time and reveals for the first time a highly dynamic direct description of LDL, where we could follow large domain fluctuations of the protrusions in real time. To tackle the inherent flexibility and heterogeneity of LDL, the cryo-EM maps are further assessed by 3D variability analysis. Our study gives a detailed explanation how to approach the intrinsic flexibility of a complex system comprising lipids and protein.

Virtually same oxidizability of LDL but higher Lp(a) levels in arterial compared to venous plasma.

Plaque formation is confined to the arterial trunk. We assumed that due to the higher aeration of arterial compared to venous blood, higher levels of the atherogenic agent oxidized LDL might be present in arteries, contributing to plaque formation. We aimed to compare (i) the basal oxidative status of LDL in arterial and venous blood and (ii) the susceptibility of arterial and venous LDL to oxidation. The basal oxidative status of LDL was determined by measuring lipid hydroperoxide (LPO) concentrations, plasma levels of auto-antibodies against oxidized LDL, and by measuring oxidation-specific epitopes on LDL particles. The oxidizability of arterial vs. venous LDL (catalyzed by copper) was estimated by monitoring the time-course of conjugated dienes formation. Interestingly, we found the same basal oxidative status of LDL in arterial and venous plasma. LPO concentrations and levels of auto-antibodies against oxidized LDL were similar in arterial and venous plasma and amounts of oxidation-specific epitopes were similar on the respective LDL particles. Moreover, we found similar susceptibilities of arterial and venous LDL to (copper-mediated) oxidation. Lag-times until the onset of conjugated diene formation were slightly shorter in arterial compared to venous LDL in the presence of 5 µM, but not in the presence of 1 µM CuCl2. Additionally, we found significantly higher levels of the atherogenic lipoprotein(a) in arterial plasma. We conclude that not higher oxidizability of arterial LDL but higher arterial lipoprotein(a) levels might help to explain why sclerosis is confined to the arterial trunk.

Stent implantation in the superficial femoral artery: short thrombelastometry-derived coagulation times identify patients with late in-stent restenosis.

INTRODUCTION: The mechanisms of restenosis, the recurrence of luminal narrowing, are complex and incompletely understood to date. Thrombin, the pivotal enzyme in haemostasis, presumably contributes to the formation of in-stent restenosis (ISR). It was therefore the aim of our study to investigate whether blood coagulation/thrombin generation plays a critical role in the formation of ISR in peripheral artery disease patients with stent angioplasty in the superficial femoral artery. MATERIALS AND METHODS: We aimed to examine in this retrospective study whether patients with high-degree restenosis (50-75% lumen diameter reduction, n=20) are in a hypercoaguable state implying enhanced readiness to generate thrombin compared to patients with low-degree restenosis (<50% lumen diameter reduction, n=14). RESULTS: The coagulation tests calibrated automated thrombography, activated partial thromboplastin time, platelet aggregation, platelet adhesion, fibrinogen, and microparticles' procoagulant activity did not indicate a different coagulation status in the two patient groups. However, the thrombelastometry-derived value Coagulation Time (CT) was significantly shorter in the high-degree restenosis group (p=0.012), indicating a hypercoagulable state of patients with high-degree restenosis. Under our experimental conditions, CTs shorter than 444.5s identify patients at high risk (sensitivity=95%) for luminal narrowing. CONCLUSIONS: Our study supports the assumption that blood coagulation/thrombin generation plays a critical role in the development of ISR in peripheral arteries after stent insertion and that the thrombelastometry-derived CT might be a suitable value to identify peripheral artery disease patients at risk for development of high-degree in-stent restenosis in the superficial femoral artery.

Cardiac catheterization: haemostatic changes in pediatric versus adult patients.

Thrombophilic or haemorrhagic complications are possible adverse events following cardiac catheterization particularly in pediatric patients. It was therefore the aim of our study to compare the cardiac catheterization-related haemostatic changes in children with that in adults. The total of 50 patients was subdivided into Gr I (1-6 years), Gr II (7-18 years), and Gr III (19-58 years). Parameters of coagulation activation, plasma levels of various clotting factors and heparinase-modified thrombelastometry parameters were determined prior and immediately after cardiac catheterization. The haemostatic system of pediatric patients was markedly more affected by the procedure than that of adults. Levels of thrombin/antithrombin complex and prothrombin fragment 1+2 in the post-catheter plasma samples were significantly increased in Grs I and II, not in Gr III. The catheter-related decrease in fibrinogen and F II levels was higher in Gr I than in Grs II and III. F VII levels were significantly decreased in Grs I and II, not in Gr III. The catheter-related prolongation of Coagulation times was highest in Gr I, followed by Gr II and finally Gr III. A significant catheter-related decrease of maximum clot firmness was observed solely in Gr I. Our results show that cardiac catheterisation perturbs the haemostatic system of adults, and, even more pronounced, that of pediatric patients. Thus, our results indicate that children might be at a higher risk for either thrombotic complications or post-operative bleeding events than adults.

Effects of nadroparin, enoxaparin, and unfractionated heparin on endogenous formation of factor Xa and IIa and on thrombelastometry profiles in cord versus adult blood.

BACKGROUND: To date, only few pharmacokinetic studies on low-molecular-weight heparins (LMWHs) in neonates exist not allowing to formally assess pharmacodynamics of LMWHs in neonates. OBJECTIVE: To evaluate the anticoagulant effects of the two LMWHs nadroparin and enoxaparin on endogenous formation of FXa or FIIa in cord versus adult platelet-poor plasma (PPP) and on thrombelastometry profiles in cord versus adult whole blood (WB). Unfractionated heparin (UH) was the reference antithrombotic drug. METHODS: The effects of nadroparin, enoxaparin, or UH on endogenous formation of FXa or FIIa was investigated in tissue factor-activated PPP using a subsampling technique and chromogenic substrates. The anticoagulant efficacy of these drugs was also investigated in WB triggered by the physiological relevant activator collagen/endogenous thrombin using thrombelastometry. RESULTS: The major findings are (i) nadroparin is as efficient as enoxaparin concerning inhibition of the endogenous formation of FXa and FIIa, (ii) cord PPP and WB are significantly more susceptible to the addition of LMWHs or UH than adult PPP or WB, and (iii) compared by equivalent anti-FXa activity, the anticoagulant action of UH is markedly higher than that of the LMWHs in PPP and WB of neonatal or adult origin. CONCLUSIONS: Administration of LMWHs in neonates has to be performed carefully to avoid bleeding side effects due to their high anticoagulant efficacy in cord PPP and WB.

Heparinase-modified thrombelastometry: inactivation of heparin in plasma samples.

BACKGROUND: The heparinase-modified thrombelastometry (HEPTEM) assay is a promising tool to assess the coagulation status of heparinised patients. The aim of our study was to examine the heparin neutralizing capability of the HEPTEM assay in plasma samples. METHODS: In the HEPTEM assay, blood or plasma samples become activated via the intrinsic pathway in the presence of a heparin processing enzyme. RESULTS: We examined coagulation times (CTs) in the presence of increasing amounts (0-4 IU/mL) of heparin. We found that up to a concentration of 0.5 IU/mL, heparin is completely neutralized. However, CTs increased linearly in the presence of heparin concentrations higher than 0.5 IU/mL, indicating incomplete heparin neutralization in the standard HEPTEM assay. CONCLUSIONS: We provide herein a mathematical procedure to correct the misleadingly prolonged CTs (for heparin > 0.5 IU/mL) for the HEPTEM assay performed in plasma samples to allow better estimation of the coagulation status in patients requiring intense anticoagulation (e.g., patients undergoing cardiac surgery).