Dynamic changes in N-terminal pro-brain natriuretic peptide in acute coronary syndromes treated with percutaneous coronary intervention: a marker of ischemic burden, reperfusion and outcome.

BACKGROUND: Whereas N-terminal pro-brain natriuretic peptide (NT-proBNP) is approved for risk stratification of patients with acute coronary syndromes (ACS), short-term temporal changes in NT-proBNP concentrations and the optimal time points for sampling are not clear. The purpose of this study was to better define the short-term changes in NT-proBNP in relation to clinical presentation, reperfusion and prognostic value in patients with ACS, as well as to identify the optimum time points for sampling. METHODS: We studied daily plasma concentrations of NT-proBNP in 133 unselected patients with myocardial infarction (n=65), stable coronary artery disease (CAD, n=46) and no CAD (n=22) who underwent coronary angiography. RESULTS: Patients with non-ST-elevation myocardial infarction (NSTEMI) presented with markedly higher NT-proBNP than patients with ST-elevation myocardial infarction (STEMI) [1305 (741-3208) ng/L vs. 170 (70-424) ng/L, p<0.001]. Also, time to presentation from onset of pain was much longer in NSTEMI as compared to STEMI (>48 h vs. <6 h, p<0.001). Patients with NSTEMI also presented with higher NT-proBNP as compared with CAD [224 (98-732) ng/L] and no CAD [47 (26-102) ng/L; p<0.001, NSTEMI vs. both]. Following successful percutaneous coronary intervention [thrombolysis in myocardial infarction (TIMI) 3-flow established], NT-proBNP increased markedly within 24 h in patients with STEMI [718 (379-1338) ng/L, p<0.01 vs. 0 h], whereas no change in NT-proBNP was noted in patients with NSTEMI [1190 (1010-2024) ng/L, p=0.88 vs. 0 h]. In both STEMI and NSTEMI, NT-proBNP decreased significantly 96 h after successful reperfusion [STEMI -52%, 372 (189-610) ng/L, p<0.05; NSTEMI -52%, 613 (365-724) ng/L, p<0.05]. Unsuccessful reperfusion (TIMI<3) was associated with unchanged or increased NT-proBNP. NT-proBNP at 96 h and peak NT-proBNP further displayed a strong correlation with cardiac troponin T (r=0.64 and r=0.54, p<0.001), a marker of infarct size, and NT-proBNP at 96 h was a strong predictor of long-term prognosis (hazard ratio 7.29, p=0.025). CONCLUSIONS: In patients with NSTEMI, NT-proBNP may be increased as high as concentrations usually associated with acute congestive heart failure despite the absence of clinical signs. In contrast, patients with STEMI and short time to presentation may present with completely normal NT-proBNP, but dramatic short-term increases following reperfusion. NT-proBNP reflects ischemic burden, reperfusion success and prognosis, and the current data support repetitive sampling in patients with ACS.

Beta-amyloid (Abeta40, Abeta42) binding to modified LDL accelerates macrophage foam cell formation.

Apart from its role as a risk factor in arteriosclerosis, plasma cholesterol is increasingly recognized to play a major role in the pathogenesis of Alzheimer's disease (AD). Moreover, alterations of intracellular cholesterol metabolism in neuronal and vascular cells are of considerable importance for the understanding of AD. Cellular cholesterol accumulation enhances the deposition of insoluble beta-amyloid peptides, which is considered a hallmark in the pathogenesis of AD. In order to test the hypothesis, whether exogenous beta-amyloid peptides (Abeta42, Abeta40) might contribute to cellular cholesterol accumulation by opsonization of lipoproteins, we compared the binding and uptake of native LDL, enzymatically modified LDL (E-LDL), copper oxidized LDL (Ox-LDL) and HDL as control, preincubated either in the absence or presence of Abeta42 or Abeta40, by human monocytes or monocyte-derived macrophages. Incubation of monocytes and macrophages with Abeta-lipoprotein-complexes lead to increased cellular free and esterified cholesterol when compared to non-opsonized lipoproteins, except for HDL. Furthermore, the cellular uptake of these complexes regulated Abeta-receptors such as FPRL-1 or LRP/CD91. In summary, our results suggest that Abeta42 and Abeta40 act as potent opsonins for LDL, E-LDL and Ox-LDL and enhance cellular cholesterol accumulation as well as Abeta-deposition in vessel wall macrophages.

Genetic variants in the NOD2/CARD15 gene are associated with early mortality in sepsis patients.

OBJECTIVE: Genetic variants in the NOD2/CARD15 gene resulting in a diminished capacity to activate NF-kappaB in response to bacterial cell wall products have been associated with Crohn's disease (CD). Recently, we found an association between the variant Leu1007fsinsC of the NOD2/CARD15 gene (SNP13) and a significantly increased rate of transplant related mortality (TRM) due to intestinal and pulmonary complications in stem cell transplantation (SCT). To assess a possible contribution of variants in the NOD2/CARD15 gene to sepsis related mortality (SRM) we investigated 132 prospectively characterised, consecutive patients with sepsis. DESIGN AND PATIENTS: The three most common NOD2/CARD15 variants (Arg702Trp, Gly908Arg, and Leu1007fsinsC) were determined in 132 prospectively characterised patients with sepsis attended to three intensive care units at the University of Regensburg by Taqman PCR. NOD2/CARD15 genotype and major patients' characteristics were correlated with SRM. RESULTS: Patient groups with and without NOD2/CARD15 variants did not differ in their clinical characteristics such as median age, gender, reason for admission or APACHE score; however, SRM (day 30) was increased in patients with NOD2/CARD15 coding variants (42 vs. 31%) and was highest (57%) in 8 patients carrying the Leu1007fsinsC variant (p < 0.05). Multivariate analysis demonstrated the Leu1007fsinsC genetic variant as an independent risk factor for SRM. CONCLUSION: Our findings indicate a major role of NOD2/CARD15 coding variants for SRM. This may be indicative for a role of impaired barrier function and bacterial translocation in the pathophysiology of early sepsis related death.

Effectiveness of parathyroid-hormone measurement in detecting patients with multiple gland disease causing primary hyperparathyroidism.

BACKGROUND AND AIM: Intraoperative parathyroid hormone measurement (iPTH) has strengthened the successful use of minimal-invasive approaches in surgery of primary hyperparathyroidism (pHPT). The aim of the study was to evaluate the efficacy of iPTH monitoring in treating pHPT resulting from multiple gland disease. MATERIALS AND METHODS: In this retrospective study, 58 patients with pHPT underwent surgery (minimally invasive or open exploration) between January 2003 and July 2005. iPTH levels were routinely measured at the start of anesthesia, in any case before skin incision, and 10 as well as 15 min after removal of abnormal gland(s). A drop in iPTH >50% after 10 min and >60% after 15 min was considered adequate to prove the success of the removal of the abnormal gland(s). The removed tissue was examined histologically by immediate frozen section. RESULTS: A single gland disease was found in 51 (88%) cases, a multiple gland disease (double adenoma or hyperplasia) in 7 (12%) cases. In all cases of single adenoma, an adequate drop of iPTH was seen after removal of the pathologic gland. In contrast, in all cases with a second adenoma, an adequate drop in iPTH was detected only after removal of both adenoma/hyperplasia. Immediate sectioning was only helpful for identification of removed tissue, but was no help in deciding whether to search for an additional gland. The follow-up showed no late disease recurrence. CONCLUSION: The measurement of iPTH is an effective and safe means in treating single gland disease as well as multiple gland disease (adenoma/hyperplasia) causing pHPT and also allows a successful limited dissection via minimally invasive parathyroidectomy.

Adenosine triphosphate binding cassette (ABC) transporters are expressed and regulated during terminal keratinocyte differentiation: a potential role for ABCA7 in epidermal lipid reorganization.

Central aspects of the cellular lipid trafficking mechanisms that occur during keratinocyte differentiation are still not well understood. In the past years, evidence has accumulated to suggest that members of the superfamily of adenosine triphosphate binding cassette (ABC) transporters are critically involved in the transmembrane transport of cellular lipids. To test the hypothesis that ABC molecules are potentially involved in the epidermal transport of sphingolipids, glycerophospholipids, cholesterol, and fatty acids, we performed mRNA expression profiling of all currently known ABC molecules during in vitro differentiation of human keratinocytes and HaCaT cells. We identified six ABC molecules that displayed significant regulation during differentiation of these cells. The recently cloned transporter ABCA7 was highly expressed in keratinocytes and HaCaT cells and upregulated during differentiation. Overexpression of ABCA7 in HeLa cells resulted in increased expression of intracellular and cell surface ceramide and elevated intracellular phosphatidylserine levels. Given the observation that during terminal keratinocyte differentiation intracellular and surface ceramide levels are increased, our results render ABCA7 a candidate regulator of ceramide transport in this process. In addition to ABCA7, the cholesterol transporters ABCB1 and ABCG1 and the glutathione/glucuronide sulfate transporters ABCC1, ABCC3, and ABCC4, were strongly upregulated during keratinocyte and HaCaT cell differentiation. These findings support the notion that ABCB1 and ABCG1 are potentially implicated in cholesterol transport, whereas ABCC1, ABCC3, and ABCC4 are candidate regulators of the translocation of sulfated lipids during stratum corneum keratinization. Our results suggest specific biologic functions for members of the ABC transporter family in epidermal lipid reorganization during terminal keratinocyte differentiation.

Changes in HDL-associated apolipoproteins relate to mortality in human sepsis and correlate to monocyte and platelet activation.

OBJECTIVE: Lipoproteins modulate vascular cell function in inflammation. In this study, we analyzed whether plasma concentrations of lipoproteins and apolipoproteins in human sepsis are related to patient survival and the activation of blood monocytes and platelets. DESIGN: Observational study. SETTING: Medical and surgical intensive care units (ICU) of a university hospital. PATIENTS: 151 consecutive patients after sepsis criteria had been met for the first time. INTERVENTIONS: None. MEASUREMENTS: Plasma lipoproteins, apolipoproteins, platelet CD62P-expression, monocyte HLA-DR-expression, SAPS II-scores (Simplified Acute Physiology Score) and 30-day-mortality were recorded. RESULTS: Total cholesterol, high-density-lipoprotein (HDL) and low-density-lipoprotein (LDL) cholesterol, apolipoprotein (apo)-AI and apo-B were all found to be significantly lower in non-survivors than in survivors. In contrast to other (apo)lipoproteins, apo-AI and HDL cholesterol further decreased in non-survivors during the ICU stay. Logistic regression analysis revealed apo-AI to be an independent predictor of 30-day-mortality. A significant inverse correlation was found for apo-AI/HDL-cholesterol and platelet activation. Later in the course of the disease, HLA-DR expression on monocytes correlated positively to apo-AI and apo-CI concentrations and inversely to the apo-E concentration. CONCLUSION: Low apo-AI is independently related to 30-day mortality in human sepsis and the decrease in apo-AI/HDL cholesterol correlates to increased platelet activation. Moreover, changes in apolipoproteins supposed to modulate lipopolysaccharide effects, such as apo-CI and apo-E, correlate to monocyte activation.

High density lipoprotein modulates platelet function.

BACKGROUND: Platelet activation by atherogenic lipoproteins can be antagonized by high density lipoprotein (HDL), probably via interaction with the ATP-binding cassette transporter A1 (ABCA1). METHODS: ABCA1 expression and its association with cholesterol rich membrane domains was analyzed by mRNA and Western blot analysis. HDL effects on platelet receptor clustering were analyzed by flow cytometric analysis of fluorescence resonance energy transfer between fluorochrome-labeled antibodies. RESULTS: ABCA1 expression increased upon megakaryocytic differentiation of human stem cells and ABCA1 protein partially associated to LubroIWX-resistant membrane domains. Plasma HDL-cholesterol in healthy donors negatively correlated to the platelet membrane cholesterol content. Receptor cluster analysis revealed a decrease in the association of Gplb and FcgammaRII upon incubation of platelets with HDL3. CONCLUSION: Our results suggest that HDL modulates platelet reactivity by altering lipid raft associated receptor clustering.

Regulation of surface CD163 expression and cellular effects of receptor mediated hemoglobin-haptoglobin uptake on human monocytes and macrophages.

Local dysregulation of iron metabolism is suggested to contribute to atherosclerotic lesion development through hemoglobin scavenging pathways. We evaluated the effects of CD163-mediated uptake of hemoglobin-haptoglobin (HbHp) complexes on surface CD163 and intracellular heme oxygenase-1 expression and the secretion of pro- and antiinflammatory cytokines by macrophages. We found that increased availability of HbHp complexes triggers the upregulation of surface CD163, and also results in a dose-dependent secretion of IL-6 and IL-10.

E-LDL and Ox-LDL differentially regulate ceramide and cholesterol raft microdomains in human Macrophages.

Atherosclerosis is characterized by the generation of lipid-loaded macrophage-derived foam cells. To study the effect of different types of atherogenic lipoproteins, human macrophages were loaded with enzymatically degraded low density lipoprotein (E-LDL) or oxidized LDL (Ox-LDL). Cellular cholesterol content was increased by E-LDL, whereas Ox-LDL increased the ceramide content. Cell surface expression analysis by flow cytometry and confocal microscopy revealed that Ox-LDL increased ceramide and lactosylceramide expression compared to E-LDL loading and induced ceramide rafts, whereas loading with E-LDL induced cholesterol-rich microdomains. Formation of different rafts may have consequences for raft associated signaling in cholesterol homeostasis and apoptosis in human macrophages.

Alteration of the pulmonary surfactant system in full-term infants with hereditary ABCA3 deficiency.

RATIONALE: ABCA3 mutations are known to cause fatal surfactant deficiency. OBJECTIVE: We studied ABCA3 protein expression in full-term newborns with unexplained respiratory distress syndrome (URDS) as well as the relevance of ABCA3 mutations for surfactant homeostasis. METHODS: Lung tissue of infants with URDS was analyzed for the expression of ABCA3 in type II pneumocytes. Coding exons of the ABCA3 gene were sequenced. Surfactant protein expression was studied by immunohistochemistry, immunoelectron microscopy, and Western blotting. RESULTS: ABCA3 protein expression was found to be greatly reduced or absent in 10 of 14 infants with URDS. Direct sequencing revealed distinct ABCA3 mutations clustering within vulnerable domains of the ABCA3 protein. A strong expression of precursors of surfactant protein B (pro-SP-B) but only low levels and aggregates of mature surfactant protein B (SP-B) within electron-dense bodies in type II pneumocytes were found. Within the matrix of electron-dense bodies, we detected precursors of SP-C (pro-SP-C) and cathepsin D. SP-A was localized in small intracellular vesicles, but not in electron-dense bodies. SP-A and pro-SP-B were shown to accumulate in the intraalveolar space, whereas mature SP-B and SP-C were reduced or absent, respectively. CONCLUSION: Our data provide evidence that ABCA3 mutations are associated not only with a deficiency of ABCA3 but also with an abnormal processing and routing of SP-B and SP-C, leading to severe alterations of surfactant homeostasis and respiratory distress syndrome. To identify infants with hereditary ABCA3 deficiency, we suggest a combined diagnostic approach including immunohistochemical, ultrastructural, and mutation analysis.

MK-383 (tirofiban) induces a GPIIb/IIIa receptor conformation which differs from the resting and activated receptor.

The platelet integrin alphaIIb beta3 (GPIIb/IIIa) acts as a receptor for fibrinogen, playing a critical role in platelet aggregation. GPIIb/IIIa antagonists, which block the receptor-ligand interaction, have been accused of causing occasional thrombocytopenia, probably via drug-induced platelet activation or immunogenic neoepitopes. We, therefore, analyzed the effects of the GPIIb/IIIa antagonist MK-383 (tirofiban) on platelet activation and GpIIb/IIIa conformation. At a concentration of 10(-7) mol/l, MK-383 completely inhibited fibrinogen binding to in vitro stimulated platelets. Simultaneously, the GPIIb/IIIa expression density increased, similar to that on activated platelets, but no effect on P-selectin expression or the formation of platelet-leukocyte aggregates could be observed, indicating that MK-383 binding did not induce general platelet activation. The GPIIb/IIIa receptor conformation was further analyzed by fluorescence resonance energy transfer analysis between fluorochrome-labeled antibodies against different GpIIb/IIIa epitopes. As a result, MK-383 induced a receptor conformation that differed from the resting as well as the activated receptor as induced by ADP or TRAP-6. This conformational modulation of GPIIb/IIIa presents an interesting mechanism which may be linked to receptor recruitment without inducing general platelet activation.

Cloning and characterization of a novel apolipoprotein A-I binding protein, AI-BP, secreted by cells of the kidney proximal tubules in response to HDL or ApoA-I.

Apolipoprotein A-I (apoA-I) is the major apolipoprotein of high-density lipoproteins (HDL) and has an important role in the regulation of the stability, lipid transport, and metabolism of HDL particles. To identify novel proteins that are involved in HDL metabolism, we used mature apoA-I (amino acids 25-267) as a bait for the screening of a human liver two-hybrid cDNA library. Among the identified genes, several encoded known proteins, including serum amyloid A(2a) (SAA(2a)), apoC-I, and phosphodiesterase HCAM1 (PDE1A), found to interact with apoA-I. In addition, we have cloned a novel 29 kDa apoA-I interacting protein, which we named AI-BP (apoA-I binding protein). The AI-BP encoding gene, APOA1BP, which is located on chromosome 1q21, is composed of six exons and five introns and spans 2.5 kb. Northern blot analysis demonstrated ubiquitous expression of the APOA1BP mRNA with the highest expression in kidney, heart, liver, thyroid gland, adrenal gland, and testis. AI-BP protein is not detectable in serum of healthy probands, but serum samples of patients with septic syndromes may contain elevated levels of AI-BP. Significant amounts of AI-BP protein are found in cerebrospinal fluid and urine of healthy probands. The stimulation of cells derived from the kidney proximal tubules with apoA-I or HDL induces a concentration-dependent secretion of AI-BP indicating an important role for AI-BP, in the renal tubular degradation or resorption of apoA-I.