975 resultados para antimicrobial and antiproliferative assays
Resumo:
The performance of high-resolution CZE for determination of carbohydrate-deficient transferrin (CDT) in human serum based on internal and external quality data gathered over a 10-year period is reported. The assay comprises mixing of serum with a Fe(III) ion-containing solution prior to analysis of the iron saturated mixture in a dynamically double-coated capillary using a commercial buffer at alkaline pH. CDT values obtained with a human serum of a healthy individual and commercial quality control sera are shown to vary less than 10%. Values of a control from a specific lot were found to slowly decrease as function of time (less than 10% per year). Furthermore, due to unknown reasons, gradual changes in the monitored pattern around pentasialo-transferrin were detected, which limit the use of commercial control sera of the same lot to less than 2 years. Analysis of external quality control sera revealed correct classification of the samples over the entire 10-year period. Data obtained compare well with those of HPLC and CZE assays of other laboratories. The data gathered over a 10-year period demonstrate the robustness of the high-resolution CZE assay. This is the first account of a CZE-based CDT assay with complete internal and external quality assessment over an extended time period.
Resumo:
Postnatally, the mammary gland undergoes continuous morphogenesis and thereby is especially prone to malignant transformation. Thus, the maintenance of the epithelium depends on a tight control of stem cell recruitment. We have previously shown that epithelial overexpression of the EphB4 receptor results in defective mammary epithelial development and conferred a metastasizing tumor phenotype on experimental mouse mammary tumors accompanied by a preponderance of progenitor cells. To analyze the effect of EphB4 overexpression on mammary epithelial cell fate, we have used Fluorescence Activated Cell Sorting (FACS) analyses to quantify epithelial sub-populations and repopulation assays of cleared fat pads to investigate their regenerative potential. These experiments revealed that deregulated EphB4 expression leads to an augmentation of bi-potent progenitor cells and to a shift of the differentiation pathway towards the luminal lineage. The analyses of the ductal outgrowths indicated that EphB4 overexpression leads to enforced branching activity, impedes ductal differentiation and stimulates angiogenesis. To elucidate the mechanisms forwarding EphB4 signals, we have compared the expression profile of defined cell populations between EphB4 transgene and wild type mammary glands concentrating on the wnt signaling pathway and on genes implicated in cell migration. With respect to wnt signaling, the progenitor cell population was the most affected, whereas the stem cell-enriched population showed the most pronounced deregulation of migration-associated genes. Thus, the luminal epithelial EphB4 signaling contributes, most likely via wnt signaling, to the regulation of migration and cell fate of early progenitors and is involved in the determination of branching points along the ductal tree.
Resumo:
Various in-vitro chemosensitivity and resistance assays (CSRAs) have been demonstrated to be helpful decision aids for non-neurological tumors. Here, we evaluated the performance characteristics of two CSRAs for glioblastoma (GB) cells. The chemoresponse of fresh GB cells from 30 patients was studied in vitro using the ATP tumor chemoresponse assay and the chemotherapy resistance assay (CTR-Test). Both assay platforms provided comparable results. Of seven different chemotherapeutic drugs and drug combinations tested in vitro, treosulfan plus cytarabine (TARA) was the most effective, followed by nimustine (ACNU) plus teniposide (VM26) and temozolomide (TMZ). Whereas ACNU/VM26 and TMZ have proven their clinical value for malignant gliomas in large randomized studies, TARA has not been successful in newly diagnosed gliomas. This seeming discrepancy between in vitro and clinical result might be explained by the pharmacological behavior of treosulfan. Our results show reasonable agreement between two cell-based CSRAs. They appear to confirm the clinical effectiveness of drugs used in GB treatment as long as pharmacological preconditions such as overcoming the blood-brain barrier are properly considered.
Resumo:
Ketamine and norketamine are being transported across the blood brain barrier and are also entering from blood into cerebrospinal fluid (CSF). Enantioselective distributions of these compounds in brain and CSF have never been determined. The enantioselective CE based assay previously developed for equine plasma was adapted to the analysis of these compounds in equine brain via use of an acidic pre-extraction of interferences prior to liquid/liquid extraction at alkaline pH. CSF can be treated as plasma. With 100 mg of brain tissue and 0.5 mL of CSF or plasma, assay conditions for up to 30 nmol/g and 6 μM, respectively, of each enantiomer with LOQs of 0.5 nmol/g and 0.1 μM, respectively, were established and the assays were applied to equine samples. CSF and plasma samples analyzed stemmed from anesthetized patient horses and brain, CSF and plasma were obtained from anesthetized horses that were euthanized with an overdose of pentobarbital. Data obtained indicate that ketamine and norketamine enantiomers are penetrating into brain and CSF with those of ketamine being more favorably transported than norketamine, whereas metabolites of norketamine are hindered. More work is required to properly investigate possible stereoselectivities of the ketamine metabolism and transport of metabolites from blood into brain tissue and CSF.
Resumo:
Cathelicidins constitute potent antimicrobial peptides characterized by a high cationic charge that enables strong interactions with nucleic acids. In fact, the only human cathelicidin LL-37 triggers rapid sensing of nucleic acids by plasmacytoid dendritic cells (pDC). Among the porcine cathelicidins, phylogenetic analysis of the C-terminal mature peptide showed that porcine myeloid antimicrobial peptide (PMAP)-36 was the most closely related of the 11 porcine cathelicidins to human LL-37. Despite several investigations evaluating potent antimicrobial functions of porcine cathelicidins, nothing is known about their ability to promote pDC activation. We therefore investigated the capacity of the proline-arginine-rich 39-aa peptide, PMAP-23, PMAP-36, and protegrin-1 to complex with bacterial DNA or synthetic RNA molecules and facilitate pDC activation. We demonstrate that these peptides mediate a rapid and efficient uptake of nucleic acids within minutes, followed by robust IFN-α responses. The highest positively charged cathelicidin, PMAP-36, was found to be the most potent peptide tested for this effect. The peptide-DNA complexes were internalized and also found to associate with the cell membranes of pDC. The amphipathic conformation typical of PMAP-36 was not required for IFN-α induction in pDC. We also demonstrate that PMAP-36 can mediate IFN-α induction in pDC stimulated by Escherichia coli, which alone fail to activate pDC. This response was weaker with a scrambled PMAP-36, relating to its lower antimicrobial activity. Collectively, our data suggest that the antimicrobial and nucleic acid-complexing properties of cathelicidins can mediate pDC activation-promoting adaptive immune responses against microbial infections.
Resumo:
PURPOSE Contamination with bacteria and/or fungi is a serious complication in organ-cultured corneas. Hence, antibiotic and antifungal agents are added to the culture medium. The concentration of different antimicrobial and antifungal additives to the media over time has so far not been investigated in detail and is the aim of this study. METHODS Nine human fresh corneoscleral discs were stored in corneal culture medium consisting of 2% fetal bovine serum and minimal essential medium. In addition, the culture medium contained 1200 μg/mL penicillin G, 25 μg/mL amphotericin B, 120 μg/mL streptomycin, and 100 μg/mL voriconazole. The concentration of amphotericin B used was 10 times higher than in clinical routine to facilitate its detection. The cultures were kept at 37°C for 28 days. At days 0, 7, 14, 21, and 28, samples of the culture medium were harvested for analysis of antimicrobial concentrations by liquid chromatography and electrospray ionization tandem mass spectrometry. RESULTS During corneal storage, the concentration of all antibiotics and antifungal agents declined significantly. By day 28, penicillin G was reduced to 14% of the original concentration. Amphotericin B and streptomycin retained approximately 60% of the original concentration to the end of the experiment and voriconazole maintained stable concentrations after an initial decline to approximately 80% at 7 days. CONCLUSIONS Throughout the entire storage period, the concentrations of penicillin G, streptomycin, and voriconazole exceeded the minimum inhibitory concentrations of all common contaminants, obviating the need for a change of the medium for antimicrobial reasons. Based on the minimum inhibitory concentrations and our findings, the initial concentration of amphotericin B should be raised to 5 μg/mL.
Resumo:
Dielectrophoresis (DEP) has been used to manipulate cells in low-conductivity suspending media using AC electrical fields generated on micro-fabricated electrode arrays. This has created the possibility of performing automatically on a micro-scale more sophisticated cell processing than that currently requiring substantial laboratory equipment, reagent volumes, time, and human intervention. In this research the manipulation of aqueous droplets in an immiscible, low-permittivity suspending medium is described to complement previous work on dielectrophoretic cell manipulation. Such droplets can be used as carriers not only for air- and water-borne samples, contaminants, chemical reagents, viral and gene products, and cells, but also the reagents to process and characterize these samples. A long-term goal of this area of research is to perform chemical and biological assays on automated, micro-scaled devices at or near the point-of-care, which will increase the availability of modern medicine to people who do not have ready access to large medical institutions and decrease the cost and delays associated with that lack of access. In this research I present proofs-of-concept for droplet manipulation and droplet-based biochemical analysis using dielectrophoresis as the motive force. Proofs-of-concept developed for the first time in this research include: (1) showing droplet movement on a two-dimensional array of electrodes, (2) achieving controlled dielectric droplet injection, (3) fusing and reacting droplets, and (4) demonstrating a protein fluorescence assay using micro-droplets. ^
Resumo:
Rhodobacter sphaeroides 2.4.1 is a Gram negative facultative photoheterotrophic bacterium that has been shown to have an N-acyl homoserine lactone-based quorum sensing system called cer for c&barbelow;ommunity e&barbelow;scape r&barbelow;esponse. The cer ORFs are cerR, the transcriptional regulator, cerI, the autoinducer synthase and cerA , whose function is unknown. The autoinducer molecule, 7,8- cis-N-(tetradecenoyl) homoserine lactone, has been characterized. The objective of this study was to identify an environmental stimulus that influences the regulation of cerRAI and, to characterize transcription of the cer operon. ^ A cerR::lacZ transcriptional fusion was made and β-Galactosidase assays were performed in R. sphaeroides 2.4.1 strains, wild type, AP3 (CerI−) and AP4 (CerR−). The cerR::lacZ β-Galactosidase assays were used as an initial survey of the mode of regulation of the Cer system. A cerA::lacZ translational fusion was created and was used to show that cerA can be translated. The presence of 7,8-cis-N-(tetradecenoyl) homoserine lactone was detected from R. sphaeroides strains wild type and AP4 (CerR−) using a lasR::lacZ translational fusion autoinducer bioassay. The cerR::lacZ transcriptional fusion in R. sphaeroides 2.4.1 wild type was tested under different environmental stimuli, such as various carbon sources, oxygen tensions, light intensities and culture media to determine if they influence transcription of the cer ORFs. Although lacZ assay data implicated high light intensity at 100 W/m2 to stimulate cer transcription, quantitative Northern RNA data of the cerR transcript showed that low light intensity at 3 W/m2 is at least one environmental stimulus that induces cer transcription. This finding was supported by DNA microarray analysis. Northern analysis of the cerRAI transcript provided evidence that the cer ORFs are co-transcribed, and that the cer operon contains two additional genes. Bioinformatics was used to identify genes that may be regulated by the Cer system by identifying putative lux box homologue sequences in the presumed promoter region of these genes. Genes that were identified were fliQ, celB and calsymin, all implicated in interacting with plants. Primer extension was used to help localize cis-elements in the promoter region. The cerR::lacZ transcriptional fusion was monitored in a subset of different global DNA binding transcriptional regulator mutant strains of R. sphaeroides 2.4.1. Those regulators involved in maintaining an anaerobic photosynthetic lifestyle appeared to have an effect. Collectively, the data imply that R. sphaeroides 2.4.1 activates the Cer system when grown anaerobic photosynthetically at low light intensity, 3 W/m2, and it may be involved in an interaction with plants. ^
Resumo:
Hematopoietic growth factors play important roles in regulating blood cell growth and development in vivo. In this work, we investigated the signaling mechanisms of two growth factors with clinical significance, erythropoietin (Epo) and granulocyte colony-stimulating factor (G-CSF). Epo is essential for the survival, proliferation and differentiation of red blood cell progenitors, while G-CSF plays an important role in controlling mature neutrophil production. To identify which amino acid(s) and/or motif in EpoR is responsible for cell survival, wild type or mutant EpoR isoforms were transfected into the growth factor-dependent 32D cell line. Proliferation and apoptosis assays demonstrated that an EpoR isoform that lacks intracellular tyrosine residues and is truncated after 321 amino acids in the cytoplasmic tail (EpoR 1-321) mediates Epo-dependent cell survival. Furthermore, in absence of fetal calf serum (FCS), Epo signaling through wild type or mutant receptors supported anti-apoptosis, but not proliferation during 72 hours in response to Epo. To investigate the signaling pathway by which EpoR regulates cell survival, a dominant negative Stat5b (dnStat5b) isoform was generated and coexpressed with EpoR in stable cell lines. Expression of dnStat5b causes a significant induction of apoptosis in the presence of Epo in cells expressing EpoR 1-321, indicating that Stat5 is essential for survival signaling through tyrosine independent sequences in the EpoR. In a second project to investigate G-CSF signaling, we studied mechanisms by which G-CSF regulates the expression of PU.1, an important transcription factor in myeloid and B cell development. We demonstrated, by immunoblot and real time RT-PCR, that PU.1 is induced by G-CSF ex vivo as well as in vivo. To test whether G-CSF signaling through Stat3 is required for PU.1 regulation, the upstream region of the PU.1 gene was analyzed for potential Stat3 binding motifs. Four potential sites were identified; chromatin immunoprecipitations demonstrated that G-CSF activated Stat3 binds to 3 of the 4 binding motifs. In addition, PU.1 induction by G-CSF was completely abrogated in bone marrow from hematopoietic conditional Stat3 knockout mice. These results indicate an important role for Stat3 in G-CSF-dependent PU.1 gene regulation. Collectively, our works demonstrate that Stat protein play important and diverse roles in hematopoietic growth factor signaling. ^
Resumo:
Current shortcomings in cancer therapy require the generation of new, broadly applicable, potent, targeted treatments. Here, an adenovirus is engineered to replicate specifically in cells with active human telomerase promotion using a modified hTERT promoter, fused to a CMV promoter element. The virus was also modified to contain a visible reporter transgene, GFP. The virus, Ad/hTC-GFP-E1 was characterized in vitro and demonstrated tumor specific activity both by dose and over time course experiments in a variety of cell lines. In vivo, Ad/hTC-GFP-E1 was affected at suppressing tumor growth and providing a survival benefit without causing any measurable toxicity. To increase the host range of the vector, the fiber region was modified to contain an RGD-motif. The vector, AdRGD/hTC-GFP-E1, was recharacterized in vitro, revealing heightened levels of infectivity and toxicity however maintaining a therapeutic window between cancer and normal cell toxicity. AdRGD/hTC-GFP-E1 was administered in vivo by limb perfusion and was observed to be tumor specific both in expression and replication. To further enhance the efficacy of viral vectors in lung delivery, asthma medications were investigated for their abilities to enhance transgene delivery and expression. A combination of bronchodilators, mast cell inhibitors, and mucolytic agents was devised which demonstrated fold increases in expression in immunocompetent mouse lungs as single agents and more homogenous, intense levels of expression when done in combination of all agents. To characterize the methods in which some cancers are resistant or may become resistant to oncolytic treatments, several small molecule inhibitors of metabolic pathways were applied in combination with oncolytic infection in vitro. SP600125 and PD 98059, respective JNK and ERK inhibitors, successfully suppressed oncolytic toxicity, however did not affect infectivity or transgene expression of Ad/hTC-GFP-E1. JNK and ERK inhibition did significantly suppress viral replication, however, as analyzed by lysate transfer and titration assays. In contrast, SB 203580, an inhibitor for p38, did not demonstrate any protective effects with infected cells. Flow cytometric analysis indicated a possible correlation with G1 arrest and suppressed viral production, however more compounds must be investigated to clarify this observation. ^
Resumo:
Over-expression of the receptor tyrosine kinase ErbB2 is prevalent in approximately 30% of human breast carcinomas and confers Taxol resistance. In breast cancer cells, Taxol induces tubulin polymerization and hyperstable microtubule formation. This in turn prematurely activates Cdc2 kinase allowing early entry into the G2/M phase of the cell cycle resultant in mitotic catastrophe followed by apoptosis. Over-expression of ErbB2 upregulates p21Cip1, which inhibits Cdc2 activation, and leads to Taxol resistance in patients. However, the mechanism of ErbB2-mediated p21 Cip1 upregulation is unclear. Here in this study, we investigated the mechanism of ErbB2 downstream signaling events leading to upregulation. The CDKN1A (p21Cip1) gene promoter contains numerous cis-elements including a Signal transducer and activator of transcription (STAT) Inducable Element (SIE) located at -679 kb. Our studies showed ErbB2 overexpressing cells had increased activated levels of STAT3, and therefore we hypothesized that STAT3 is responsible for the upregulation of the p21Cip1 promoter by ErbB2. EMSA and ChIP assays confirmed the binding of STAT3 to the p21Cip1 promoter and luciferase assays showed higher p21 Cip1 promoter activity in ErbB2 over-expressing transfectants when compared to parental cells, in a STAT3 binding site dependant manner. Additionally, reduced level of STAT3 led to reduced p21Cip1 protein expression and promoter activity indicating that both the STAT3 binding site and STAT3 protein are required for ErbB2-mediated p21Cip1 upregulation. Further investigation of ErbB2 downstream signaling showed increased Src kinase activity in ErbB2 over-expressing cells which was required for ErbB2-mediated STAT3 activation and p21Cip1 increase. Treatment of ErbB2 over-expressing resistant cells with STAT3 inhibitor peptides sensitized the cells to Taxol. In addition to classical signal transduction pathways, I identified a novel ErbB2 mediated regulatory mechanism of p21Cip1. I found that a nuclear ErbB2 and STAT3 complex binds directly to the p21Cip1 promoter offering a non-classical mechanism of p21Cip1 promoter regulation. These data suggest that ErbB2 over-expression can confer Taxol resistance of breast cancer cells by transcriptional upregulation of p21 Cip1 via activation of STAT3 by Src kinase and also by cooperation with nuclear ErbB2. The data suggest a potential clinical mechanism for STAT3 inhibitors in sensitizing ErbB2 over-expressing breast cancers to Taxol. ^
Resumo:
Aortic aneurysms and dissections are the 15th most common cause of death in the United States. Genetic factors contribute to the pathogenesis of thoracic aortic aneurysms and dissections (TAAD). Currently, six loci and four genes have been identified for familial TAAD. Notably, mutations in smooth muscle cell (SMC) contractile genes, ACTA2 and MYH11, are responsible for 15% of familial TAAD, suggesting that proper SMC contraction is important for normal aorta function. Therefore, we hypothesize that mutations in other genes encoding SMC contractile proteins also cause familial TAAD. ^ To test this hypothesis, we used a candidate gene approach to identify causative mutations in SMC contractile genes for familial TAAD. Sequencing DNA in 80 TAAD patients from unrelated families, we identified putative mutations in eight contractile genes. We chose myosin light chain kinase (MLCK ) S1759P for further study for the following reasons: (1) Serine 1759 is conserved between vertebrates and invertebrates. (2) S1759P is predicted to be functionally deleterious by bioinformatics. (3) Low blood pressure is observed in SMC-selective MLCK-deficient mice. ^ In the presence of Ca2+/Calmodulin (CaM), MLCK containing CaM binding and kinase domains are activated to phosphorylate myosin light chain, thereby initiate SMC contraction. The CaM binding sequence of MLCK forms an α-helix structure required for CaM binding. MLCK Serine 1759 is located within the CaM binding domain. S1759P is predicted to decrease the α-helix composition in the CaM binding domain. Hence, we hypothesize that MLCK mutations cause TAAD through disturbing CaM binding and MLCK activity. ^ We further sequenced MLCK in DNA samples from additional 86 probands with familial TAAD. Two more mutations, MLCK A1754T and R1480Stop, were identified, supporting that MLCK mutations cause familial TAAD. ^ To define whether MLCK mutations disrupted CaM binding and MLCK activity, we performed co-immunoprecipitation and kinase assays. Decreased CaM binding and kinase activity was detected in A1754T and S1759P. Moreover, R1480Stop is predicted to truncate kinase and CaM binding domains. We conclude that MLCK mutations disrupt CaM binding and MLCK activity. ^ Collectively, our study is first to show mutations in genes regulating SMC contraction cause TAAD. This finding further highlights the importance of SMC contraction in maintaining aorta function. ^
Resumo:
Urines from patients administered mutagenic antineoplastic drugs were significantly mutagenic in the Ames assay, and hence may pose a genotoxic hazard to hospital personnel or family members caring for the patient. The urines were tested for mutagenicity in several different strains of Salmonella typhimurium that were uvr positive or negative (TA98, TA100, TA102, UTH8413, UTH8414). The urines were fractionated by high pressure liquid chromatography (HPLC) and the fractions assayed for mutagenicity in the strains in which the whole urine was mutagenic. Only fractions of urines containing the parent compound (cisplatin, doxorubicin, or mitomycin) were mutagenic; no other fraction showed significant mutagenicity. However, urine containing cyclophosphamide had two fractions that were mutagenic. One fraction, the fraction containing cyclophosphamide, required metabolic activation for mutagenicity. The other fraction did not require activation for mutagenicity.^ The chemical and mutagenic stability of these urines at room temperature was assayed over a 14 day period. The parent compound degraded within the first seven days, but the urines remained mutagenic. Cis-platinum was chemically stable in the urine; however, the urine decreased in mutagenicity. The decrease was probably the result of stable ligands binding to the platinum.^ Inactivation methods were developed to reduce the genotoxic hazard. Urine containing cisplatin was inactivated by complexing the cisplatin with diethyldithiocarbamate (DDTC). Oxidation with NaOCl of urines containing mitomycin and doxorubicin (sodium thiosulfate must be added to the doxorubicin urine) results in mutagenic inactivation. Inactivation of urine containing cyclophosphamide requires oxidation with alkaline potassium permaganate and trapping of active degradation products with sodium thiosulfate. Urines containing these drugs can be inactivated, but not always by the same method that inactivates the drug alone in solution. Therefore, in the future development of inactivation methods, both chemical and mutagenic assays are necessary to determine effectiveness. Methods of inactivation of mutagenic excreta developed in this study are both effective and practical. ^
Resumo:
The bryostatins are a unique family of emerging cancer chemotherapeutic candidates isolated from marine bryozoa. Although the biochemical basis for their therapeutic activity is not known, these macrolactones exhibit high affinities for protein kinase C (PKC) isozymes, compete for the phorbol ester binding site on PKC, and stimulate kinase activity in vitro and in vivo. Unlike the phorbol esters, they are not first-stage tumor promoters. The design, computer modeling, NMR solution structure, PKC binding, and functional assays of a unique class of synthetic bryostatin analogs are described. These analogs (7b, 7c, and 8) retain the putative recognition domain of the bryostatins but are simplified through deletions and modifications in the C4-C14 spacer domain. Computer modeling of an analog prototype (7a) indicates that it exists preferentially in two distinct conformational classes, one in close agreement with the crystal structure of bryostatin 1. The solution structure of synthetic analog 7c was determined by NMR spectroscopy and found to be very similar to the previously reported structures of bryostatins 1 and 10. Analogs 7b, 7c, and 8 bound strongly to PKC isozymes with Ki = 297, 3.4, and 8.3 nM, respectively. Control 7d, like the corresponding bryostatin derivative, exhibited weak PKC affinity, as did the derivative, 9, lacking the spacer domain. Like bryostatin, acetal 7c exhibited significant levels of in vitro growth inhibitory activity (1.8–170 ng/ml) against several human cancer cell lines, providing an important step toward the development of simplified, synthetically accessible analogs of the bryostatins.
Resumo:
Acknowledgements We would like to thank all of the patients, relatives and control individuals who participated in the study. We are indebted to the late Prof. Walter Muir, Chair of Developmental Psychiatry and Honorary Consultant in Learning Disability Psychiatry, University of Edinburgh, who initiated these studies and whose work was dedicated to the welfare of the patients who generously participated. We are also grateful to Mrs. Pat Malloy for her assistance with DNA collection and MAQ assays screening of the Scottish samples. The Scottish sample collection was supported by a grant from the Chief Scientist Office (CSO), part of the Scottish Government Health and Social Care Directorates. This research was funded by grants from the CSO to B.S.P. (grant CZB/4/610), The Academy of Medical Sciences/Wellcome Trust to M.J. (grant R41455) and The RS Macdonald Charitable Trust (grant D21419 together with J.H.), the Swedish Research Council (grants 2003-5158 and 2006-4472), the Medical Faculty, Umeå University, and the County Councils of Västerbotten and Norrbotten, Sweden, as well as by grants from the Fund for Scientific Research Flanders (FWO-F), the Industrial Research Fund (IWT) and the Special Research Fund of the University of Antwerp, Belgium. M.J. is funded by a Wellcome Trust Clinical Research Fellowship for MB PhD graduates (R42811). We acknowledge the contribution of the personnel of the VIB Genetic Service Facility (http://www.vibgeneticservicefacility.be/) for the genetic analysis of the Swedish samples. Research nurses Gunnel Johansson, Lotta Kronberg, Tage Johansson and Lisbeth Bertilsson are thankfully acknowledged for their help and expertise. The Betula Study was funded by the Swedish Research Council (grants 345-2003-3883 and 315-2004-6977). We also acknowledge the contribution by the staff in the Betula project