PubMed Health⌕ Search

Biomedical subjects

Charalampos Aslanidis

Publications and source records attributed to Charalampos Aslanidis.

17 recordsLinked to original sources
PubMed2006

High molecular weight adiponectin reduces apolipoprotein B and E release in human hepatocytes.

Low circulating levels of high molecular weight adiponectin (HMW-Apm) have been linked to dyslipidaemia and systemic HMW-Apm negatively correlates with very low density lipoprotein (VLDL), apolipoprotein B (ApoB), and ApoE and is positively associated with ApoA-I. Therefore, it was investigated whether HMW-Apm alters the hepatic synthesis of ApoB, ApoE, and ApoA-I or the activity of the hepatic ATP-binding cassette transporter A1 (ABCA1), as the main determinant of plasma HDL. HMW-Apm reduces hepatic ApoB and ApoE release whereas ABCA1 protein, activity and ApoA-I were not altered. Global gene expression analysis revealed that hepatic nuclear factor 4-alpha (HNF4-alpha) and HNF4-alpha regulated genes like ApoB are downregulated by HMW-Apm and this was confirmed at the mRNA and protein level. Therefore it is concluded that HMW-adiponectin may ameliorate dyslipidaemia by reducing the hepatic release of ApoB and ApoE, whereas ABCA1 function and ApoA-I secretion are not influenced.

Adiponectin↗
PubMed2006

Aberrant intestinal expression and allelic variants of mucin genes associated with inflammatory bowel disease.

Loss of intestinal mucosa integrity is an important factor in the pathogenesis of inflammatory bowel disease (IBD). The aim of this study was to characterize expression changes and allelic variants of genes related to intestinal epithelial barrier function in this disease. Therefore, ileal and colonic mucosal biopsies from nonaffected regions of patients with ulcerative colitis (UC) and Crohn's disease (CD), as well as non-IBD probands, were subjected to Affymetrix DNA-microarray analysis. Real-time reverse transcription polymerase chain reaction was used for verification in larger IBD sample numbers. Disturbed mRNA expression was identified for several mucin genes in both disease groups and tissues. A significant downregulation in the colon was obtained for MUC2 in CD and MUC12 in CD and UC. Expression analysis of all dysregulated mucins in a broad human tissue panel revealed dominant epithelial tissue-specific transcription. In silico analysis of the regulatory regions of these mucins indicated nuclear factor kappaB (NFkappaB) binding sites in each promoter. Furthermore, NFkappaB was overrepresented in mucin promoters and a component of a specific combination of transcription factors (composite module). In vivo stimulation experiments in the adenocarcinoma cell line LS174T showed inducible mucin expression by the cytokines tumor necrosis factor-alpha and transforming growth factor-beta, which could be blocked by NFkappaB signaling inhibitors. Allelic discrimination screening obtained statistically significant associations for the MUC2-V116M (P = 0.003) polymorphism with CD and for MUC4-A585S (P = 0.025), as well as MUC13-R502S (P = 0.0003) with UC. These data suggest that the disturbed expression of mucin genes and the connection to the NFkappaB pathway may influence the integrity of the intestine and therefore contribute to the pathophysiology of IBD.

Adult↗
PubMed2006

Aldehyde oxidase 1 is highly abundant in hepatic steatosis and is downregulated by adiponectin and fenofibric acid in hepatocytes in vitro.

Adiponectin protects the liver from steatosis caused by obesity or alcohol and therefore the influence of adiponectin on human hepatocytes was analyzed. GeneChip experiments indicated that recombinant adiponectin downregulates aldehyde oxidase 1 (AOX1) expression and this was confirmed by real-time RT-PCR and immunoblot. AOX1 is a xenobiotic metabolizing protein and produces reactive oxygen species (ROS), that promote cell damage and fibrogenesis. Adiponectin and fenofibric acid activate peroxisome proliferator-activated receptor-alpha (PPAR-alpha) and both suppress AOX1 protein and this is blocked by the PPAR-alpha antagonist RU486. Obesity is associated with low adiponectin, reduced hepatic PPAR-alpha activity and fatty liver, and AOX1 was found induced in the liver of rats on a high-fat diet when compared to controls. Free fatty acids and leptin, that are elevated in obesity, failed to upregulate AOX1 in vitro. The current data indicate that adiponectin reduces AOX1 by activating PPAR-alpha whereas fatty liver disease is associated with elevated hepatic AOX1. High AOX1 may be associated with higher ROS well described to induce fibrogenesis in liver tissue but may also influence drug metabolism and activity.

Adiponectin↗
PubMed2006

Adiponectin-induced secretion of interleukin-6 (IL-6), monocyte chemotactic protein-1 (MCP-1, CCL2) and interleukin-8 (IL-8, CXCL8) is impaired in monocytes from patients with type I diabetes.

BACKGROUND: Systemic adiponectin is reduced in patients with cardiovascular disease (CVD) and low adiponectin may contribute to the pathogenesis of atherosclerosis. However, circulating adiponectin is elevated in type 1 diabetes (T1D) patients, who have also a higher incidence to develop CVD. Because monocytes play an important role in atherosclerosis, we analysed the influence of adiponectin on cytokine and chemokine release in monocytes from T1D patients and controls. METHODS: Systemic adiponectin was determined in the plasma and the high-molecular weight (HMW) form of adiponectin was analysed by immunoblot. Monocytes were isolated from T1D patients and controls and the adiponectin-stimulated release of interleukin-6 (IL-6), monocyte chemotactic protein-1 (MCP-1, CCL2) and interleukin-8 (IL-8, CXCL8) was analysed. RESULTS: Systemic adiponectin was higher in T1D patients. Immunoblot analysis of the plasma indicate abundance of HMW adiponectin in T1D patients and controls. IL-6, CCL2 and CXCL8 secretion in response to adiponectin were found induced in monocytes from controls whereas only IL-6 was upregulated in T1D cells. The induction of IL-6 by adiponectin was abrogated by an inhibitor of the NFkappaB pathway. CONCLUSION: These data indicate that adiponectin-mediated induction of IL-6, CCL2 and CXCL8 is disturbed in monocytes from T1D patients and therefore elevated systemic adiponectin in T1D patients may be less protective when compared to controls.

Adiponectin↗
PubMed2006

Acute myocardial infarction and a new ABCC6 mutation in a 16-year-old boy with pseudoxanthoma elasticum.

Pseudoxanthoma elasticum is caused by mutations of the ABCC6 gene. We hereby report a case of pseudoxanthoma elasticum with clinical features dominated by early coronary involvement in addition to typical skin and ocular abnormalities. A 16-year-old survivor of acute myocardial infarction with 3-vessel coronary artery disease exhibited compound heterozygosity for the well-known nonsense mutation (c.3421C>T; R1141X) in exon 24 and a novel missense mutation (c.3662G>A; R1221H) in exon 26 of the ABCC6 gene.

Adolescent↗
PubMed2006

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.

ATP-Binding Cassette Transporters↗
PubMed2006

Decreased frequencies of ABCA1 polymorphisms R219K and V771M in Hungarian patients with cerebrovascular and cardiovascular diseases.

BACKGROUND AND PURPOSE: Genetic polymorphisms in ABC transporter A1 (ABCA1) may alter the regulation of plasma high-density lipoprotein (HDL), promoting or protecting from vascular diseases. METHODS: We investigated 244 unrelated, consecutively enrolled patients with ischemic stroke, 150 patients with coronary heart disease (CHD) and 193 blood donors for allele frequencies (AFs) of three common ABCA1 polymorphisms (R219K, V771M and I883M). RESULTS: Compared to controls (30.8 +/- 4.7 and 4.9 +/- 2.2%, respectively), decreased AFs were found in both patient groups for R219K and V771M (28.7 +/- 4.1 and 3.1 +/- 1.6% in stroke, and 25.7 +/- 5.0%; 1.3 +/- 1.3% in CHD patients, respectively). In a subset of stroke patients younger than 50, both variants occurred in significantly lower frequencies (22.4 +/- 5.5 and 1.8 +/- 1.7%, respectively). Similarly, among CHD patients younger than 60, AFs of R219K and V771M (22.6 +/- 7.5 and 0 +/- 1.6%, respectively) were decreased. V771M was almost exclusively (35/36) found in individuals carrying the R219K allele. CONCLUSIONS: Our data confirm earlier observations that ABCA1 R219K and V771M polymorphisms may be associated with a protective role against CHD and extend those to another important pathologic condition, namely stroke.

ATP Binding Cassette Transporter 1↗
PubMed2005

Identification of a novel deletion in the ABCC6 gene leading to Pseudoxanthoma elasticum.

BACKGROUND: Pseudoxanthoma elasticum (PXE) is an inherited systemic disorder, characterized by dermal, ocular and cardiovascular lesions. Genetic defects of the ABCC6 (MRP6) transporter are known to cause PXE. OBJECTIVES: The purpose of this study was to identify the genetic background of a PXE patient with a very early onset of the disease and severe systemic involvement. METHODS: Direct sequencing of genomic DNA obtained from peripheral whole blood. RESULTS: Our patient was found to be compound heterozygous with both ABCC6 alleles having genomic deletions. A novel exon 24-25 deletion was identified on one allele, while the frequently observed exon 23-29 deletion was found on the other allele. The novel deletion is 4.68 kb long and was shown to extend from intron 23 to 25. DNA-sequencing of a 2.03 kb fusion fragment revealed the deletion breakpoints within introns 23 and 25 originating in the middle of two Alu-repeats. CONCLUSION: In a patient with severe clinical symptoms, we found two genomic deletions in regions that might be important for function of the ABCC6 transporter. Genomic deletions in ABCC6 may occur more frequently in PXE patients than previously expected and future genetic analysis should focus on these mutations as well.

Adult↗
PubMed2005

Homozygosity for the 168His variant of the minor histocompatibility antigen HA-1 is associated with reduced risk of primary Sjögren's syndrome.

The genes for the human ATP-binding cassette (ABC) transporter ABCA7 and the minor histocompatibility antigen HA-1 are juxtaposed in close proximity on chromosome 19p13.3. The multispan transmembrane protein ABCA7 contains an extracellular domain that is recognized by antisera from patients with Sjögren's syndrome ("Sjögren-epitope"). Recent work from our laboratory demonstrating the involvement of ABCA7 in cellular ceramide and phosphatidylserine export suggests a role for this transporter in programmed cell death. In HA-1, a protein of unknown function, a His/Arg polymorphism (His168Arg), which constitutes the immunologic target for HA-1-specific cytotoxic T cells, has been causatively linked to graft-versus-host disease after allogeneic stem cell transplantation. Because these findings suggest a potential implication of ABCA7 and HA-1 in immune processes, we tested the hypothesis that allelic variants in both genes are associated with autoimmune disorders. We identified a total of 31 exonic single-nucleotide polymorphisms (SNP) in the ABCA7/HA-1 gene complex, nine of which represent non-synonymous nucleotide alterations. Genotypes of ABCA7 and HA-1 SNP were determined in three distinct Caucasian populations of patients with primary Sjögren's syndrome and ethnically matched controls. Comparison of allele frequencies between these groups revealed that the incidence of the HA-1 168His allele is significantly lower in Sjögren's syndrome patients than in controls (p<0.003). In contrast, the frequencies of all ABCA7 allelic variants and additional HA-1 polymorphisms were similar in patients and controls. In cohorts of patients with systemic lupus erythematosus, rheumatoid arthritis and multiple sclerosis, no significant differences in the frequencies of ABCA7 and HA-1 allelic variants were observed relative to controls. Our results suggest that the HA-1 168His variant is associated with reduced susceptibility to primary Sjögren's syndrome.

ATP-Binding Cassette Transporters↗
PubMed2005

RANTES gene polymorphisms predict all-cause and cardiac mortality in type 2 diabetes mellitus hemodialysis patients.

INTRODUCTION: Patients with type 2 diabetes (DM2) and end stage renal disease (ESRD) have a dismal survival prognosis, mainly due to cardiovascular events. There is sparse data on genetic predictors. Chemokines and their receptors are important in regulating leukocyte influx and activation in atherosclerosis, and functional polymorphisms in the respective genes are associated with cardiovascular disease risk. METHODS: We enrolled 225 prevalent Caucasian DM2 patients receiving maintenance hemodialysis in 30 centres in Southern Germany (time from dialysis initiation <2.0 years) from August 1999 to January 2000 for prospective study until December 2003. The CX3CR1 T280M, and MCP-1 -2518 and RANTES -403 and -28 promoter and intronic In1.1T/C polymorphisms were assessed by real-time PCR. Primary end point was all-cause mortality (ACM). RESULTS: Patients carrying the RANTES -403A or In1.1C allele had a significantly higher ACM risk (multivariate hazard ratio for -403A, dominant model=1.81 [95% CI: 1.22-2.67], p=0.003), mainly due to cardiac events. Similar data were obtained by haplotype analysis. The other SNPs showed no effect on survival. DISCUSSION: In DM2 patients with ESRD, ACM due to cardiac events is associated with RANTES gene variants that are known to alter the expression of this chemokine important in atherosclerosis. Further study of the role of chemokine and chemokine receptor gene variation in determining vascular end points is needed.

Aged↗
PubMed2004

Screening for functional sequence variations and mutations in ABCA1.

Mutations in the ATP-binding cassette 1 transporter gene (ABCA1) are responsible for the genetic HDL-deficiency syndromes, which are characterized by severely diminished plasma HDL-C levels and a predisposition to cardiovascular disease and splenomegaly. The ABCA1 gene contains 50 exons and codes for a 2261-amino acid long membrane protein that facilitates phospholipid and cholesterol transport. Several mutations have been identified so far as responsible either for Tangier disease or for reduced HDL levels. We have selectively looked for additional polymorphisms in functionally relevant regions of the gene in cohorts constituted of individuals with altered HDL levels as well as healthy blood donors and octogenarians, and screened for mutations in the complete coding region of selected individuals with extremely aberrant HDL levels. In the promoter region, which is important for regulation of gene expression, we have identified several polymorphisms including one VNTR polymorphism, located at a putative ZNF202 binding site, which displayed different binding of ZNF202 in an electromobility shift assay. Three novel SNPs were discovered in the promoter region (G1047C, C1152T and C1440T). The prevalence of exchange G1047C (G-395C) was found significantly increased in probands with low HDL compared to probands with high HDL. Exchanges C1152T (C-290T) and C1440T (C-7T) were significantly more frequent in the cohort with low HDL compared to healthy blood donors and octogenarians. In the C-terminal part of ABCA1, known to interact with other proteins, two novel sequence variations (F2163S and V2244I) have been found in one phenotype related to cardiovascular disease, but none in the aforementioned cohorts. In one individual with extremely high HDL levels, the V771M polymorphism was found in a homozygous state. In patients with HDL deficiency, three novel mutations have been identified (W590L, W840R and R1068C). To facilitate further research in ABCA1 sequence variations and expand our understanding of their effects, we are introducing a webpage archive (http://www.abca1-mutants.all.at) containing all sequence variations reported in ABCA1 so far. This webpage provides a more recent and detailed summary of sequence variations and mutations in ABCA1 than existing databases and should also be of interest for molecular diagnosis of ABCA1-related HDL deficiency.

ATP Binding Cassette Transporter 1↗
PubMed2004

Expression pattern and raft association of NIPSNAP3 and NIPSNAP4, highly homologous proteins encoded by genes in close proximity to the ATP-binding cassette transporter A1.

The highly homologous genes NIPSNAP3 and NIPSNAP4, with 87% amino acid identity, are members of the NIPSNAP family with putative roles in vesicular trafficking. NIPSNAP3 mRNA and NIPSNAP4 mRNA and protein were detected in multiple tissues and cells at varying degrees. Interestingly, NIPSNAP3 is most highly expressed in skeletal muscle, where NIPSNAP4 has a low mRNA abundance. NIPSNAP4 was found associated with membranes and partly localized in rafts. The ubiquitous expression of the highly conserved NIPSNAPs and their association with membranes further support an important cellular function of these proteins probably linked to vesicular trafficking. The NIPSNAP3 and NIPSNAP4 genes are located in close proximity to the 3' end of the ATP-binding cassette transporter A1 (ABCA1), whose mutations cause familial high-density lipoprotein deficiency syndromes. The adjacent genomic location and the finding that ABCA1 is a regulator of vesicular trafficking may indicate a functional relation of these proteins, even though NIPSNAP4 does not interact directly with ABCA1 nor is its expression altered in cells with mutated ABCA1.

ATP Binding Cassette Transporter 1↗
PubMed2003

Lipoprotein (a) downregulates lysosomal acid lipase and induces interleukin-6 in human blood monocytes.

The association of elevated lipoprotein (a) (Lp(a)) with an increased risk for coronary events is clearly established. This increased risk may in part be due to the activation of monocytes as major cells involved in atherogenesis. High concentrations of plasma Lp(a) were shown to influence the gene expression of human blood monocytes and in the present study we demonstrate a reduced abundance of the lysosomal acid lipase (LAL) mRNA in monocytes of patients with coronary disease and selective Lp(a) hyperlipidemia. This is also supported by in vitro studies where purified Lp(a) but not low-density lipoprotein (LDL) was shown to downregulate mRNA levels of the LAL in control monocytes. A correlation of Lp(a) serum levels and the proinflammatory cytokine IL-6 was recently also described. Therefore, we investigated whether Lp(a) is capable to enhance the release of this acute phase cytokine from human blood monocytes. Purified Lp(a) led to an increased secretion of IL-6, but not TNF-alpha arguing against a general activation of these cells. The association of reduced LAL activity with the premature development of coronary artery disease has been demonstrated in patients with hypercholesterolemia, and in the present study we show for the first time that LAL expression is suppressed in monocytes from patients with Lp(a) hyperlipidemia and by purified Lp(a). In addition, increased levels of IL-6 also predict future cardiovascular events and IL-6 secretion was also induced by purified Lp(a).

Cells, Cultured↗
PubMed2002

Molecular and functional interaction of the ATP-binding cassette transporter A1 with Fas-associated death domain protein.

ATP-binding cassette transporter A1 (ABCA1) is a major regulator of cellular cholesterol and phospholipid homeostasis. Its function has not been fully characterized and may depend on the association with additional proteins. To identify ABCA1-interacting proteins a human liver yeast two-hybrid library was screened with the 144 C-terminal amino acids of ABCA1. Fas-associated death domain protein (FADD) was identified to bind to ABCA1, and this interaction was confirmed by pull-down assays and co-immunoprecipitations. Recombinant expression of a dominant negative form of FADD or the C terminus of ABCA1 in the human hepatoma cell line HepG2 markedly reduced the transfer of phospholipids to apoA-I. This indicates that the binding of additional proteins, one of them being full-length FADD, is required for ABCA1 function. The association of FADD with ABCA1 provides an unexpected link between high density lipoprotein metabolism and an adaptor molecule mainly described in death receptor signal transduction.

ATP Binding Cassette Transporter 1↗
PubMed2002

High-speed detection of the two common paraoxonase polymorphisms Leu55-->Met and Gln192-->Arg by real-time fluorescence PCR and melting curves.

Human paraoxonase (PON1) is a calcium-dependent esterase exclusively bound to apolipoprotein A-I and clusterin, containing high-density lipoprotein (HDL) particles that hydrolyzes organophosphates and aryl esters. Several studies have indicated that PON1 can prevent low-density lipoprotein (LDL) oxidation by hydrolyzing lipid peroxides in the lipoprotein, which is the crucial first step for atherogenesis. Therefore it may protect against the development of atherosclerosis. Serum PON1 activity has been shown to be decreased in familiar hypercholesterolemia and in diseases that are associated with accelerated atherogenesis. The PON1 gene has two common coding region polymorphisms, Leu55-->Met and Gln192-->Arg. Both polymorphisms have been identified as independent risk factors for cardiovascular disease in diabetic and non-diabetic patients. We have established high-speed and easy-to-perform genotyping for the two most significant PON1 gene polymorphisms, employing the LightCycler technology and melting curves. This technique eliminates PCR contamination related to sample handling and does not require digestion of PCR products with restriction enzymes and/or fragment separation on gels.

Amino Acid Substitution↗
PubMed1998

Recent Advances in Molecular Genetics of Cardiovascular Disorders - Implications for Atherosclerosis and Diseases of Cellular Lipid Metabolism.

Two developments in molecular genetics will profoundly influence our understanding and the diagnosis of cardiovascular disorders. First, the identification of genes responsible for monogenic and polygenic traits by analysis of e.g. large pedigrees and affected sib pairs provides invaluable data regarding the role of specific genes in common diseases like arteriosclerosis, hypertension, diabetes, thrombosis/hemostasis and obesity. Besides the insights into the underlying pathophysiology, this knowledge will permit to identify persons at high risk for disease development. These patients can then obtain a targeted intervention. The second development is related to the availability of new analytical tools for molecular biology. New methods such as sequencing by hybridisation (SBH), DNA-array technology or matrix assisted laser desorption/ionisation-time of flight mass spectroscopy (MALDI-TOF) permit sequence analysis of complete genes within hours. Automated PCR-technologies with homogenous amplicon detection formats simplify PCR and permit its use in the routine laboratory setting. Considering cardiovascular diseases there is a number of genes involved in lipid metabolism (apolipoproteins, lipoprotein receptors, lipolytic enzymes), thrombosis/hemostasis (platelet receptors, pro- and anticoagulant proteins, fibrinogen, PAI's), hypertension (angiotensin converting enzyme, angiotensinogen) glucose metabolism (glucose transporters, enzymes) and obesity (hormones, receptors), that are interesting candidates for sophisticated genetic risk assessment. Furthermore, there are also gene candidates involved in processes of early atherogenesis and chronic inflammation such as complement proteins, cell adhesion molecules, and cellular receptors and enzymes. Most of these gene candidates were derived from pathophysiologic knowledge and subsequent epidemiological studies. However, it is foreseeable that in the coming years genes will be identified which were not known so far to be involved in cardiovascular diseases. Genetic studies will be of prime importance in this area, as is exemplified by animal models. In the long term, analysis of these candidate genes before the implementation of therapy will permit a targeted intervention approach towards high risk patients. This will reduce the overall costs of health care without reducing the quality.

Journal Article↗