Inhibitors can arrest the membrane activity of human islet amyloid polypeptide independently of amyloid formation

AbstractHuman islet amyloid polypeptide (hIAPP), co-secreted with insulin from pancreatic β cells, misfolds to form amyloid deposits in non-insulin-dependent diabetes mellitus (NIDDM). Like many amyloidogenic proteins, hIAPP is membrane-active: this may be significant in the pathogenesis of NIDDM. Non-fibrillar hIAPP induces electrical and physical breakdown in planar lipid bilayers, and IAPP inserts spontaneously into lipid monolayers, markedly increasing their surface area and producing Brewster angle microscopy reflectance changes. Congo red inhibits these activities, and they are completely arrested by rifampicin, despite continued amyloid formation. Our results support the idea that non-fibrillar IAPP is membrane-active, and may have implications for therapy and for structural studies of membrane-active amyloid

Automated Bus Generation for Multiprocessor SoC Design

Dedicated to my wife, Hyejung Hyeon, my parents, and my parents-in-law iii ACKNOWLEDGMENTS This work could have not been finished without the support and sacrifice of many people I had to express my gratitude. First of all, I would like to deeply thank my adviser Vincent J. Mooney III. He has supported and encouraged me to develop my dissertation with his enthusiasm and professionalism throughout all stages of my Ph.D. program. He has been a great source of ideas and provided me with invaluable feedback. In addition, Dr. Mooney has been helping me improve my English skills with his consideration. I would also like to extend my appreciation to Dr. Jeffrey Davis, Dr. Sudhakar Yalamanchili, Dr. Paul Benkeser, and Dr. Thad Starner for serving on the committee and offering constructive comments. I have to thank all Hardware/Software Codesign group members for their helps and friendship. It is obvious that, without many helps by them, my long journey a

Genetic Modifiers Influencing the Development of Albuminuria in Children with Sickle Cell Anemia

Abstract Background: Nephropathy in sickle cell anemia (SCA) begins in childhood and portends chronic kidney disease, renal failure, and early mortality among affected adults. Individuals of African descent have disproportionately higher rates of developing non-diabetic renal disease. Several candidate genetic variants have been identified, including some specific to African Americans, which are associated with the development of albuminuria and renal disease. The influence of genetic polymorphisms on albuminuria and elevated glomerular filtration rate (GFR) in children with SCA, both early signs of sickle nephropathy, has not been investigated. Objectives: To determine the influence of selected single nucleotide polymorphisms (SNPs) on the development of albuminuria and elevated GFR in children with SCA; to identify novel genetic variants influencing albuminuria and GFR by whole exome sequencing (WES). Design/Methods: Genomic DNA was collected on children with SCA enrolled in two prospective studies with pre-hydroxyurea renal assessments (n=185): (1) Hydroxyurea Study of Long-Term Effects (HUSTLE, NCT00305175, n=79) with no prior disease-modifying therapy; and (2) Transcranial Doppler (TCD) With Transfusions Changing to Hydroxyurea (TWiTCH, NCT 01425307, n=106) on chronic transfusions for abnormal TCD velocities. Albuminuria was defined as ≥30mg albumin/gm creatinine on the pre-hydroxyurea urine specimen. GFR was measured in HUSTLE using plasma DTPA (technetium 99m-labeled diethylenetriaminepentaacetic acid) clearance, and estimated GFR (eGFR) in TWiTCH based on serum creatinine. DNA samples were genotyped for 8 candidate SNPs previously associated with renal disease, using PCR-based allelic discrimination, bidirectional Sanger sequencing, and analysis of variable number tandem repeats (VNTR). Associations between albuminuria and genetic polymorphisms were tested using an additive model and correlation trend test. Linked WES data from the same patients were analyzed to identify other variants associated with albuminuria and GFR. Results: Albuminuria was present in 13.1% of patients, including 16.3% in HUSTLE and 11.0% in TWiTCH. APOL1 genetic variants were common (G1 allele frequency = 21.9%, G2 allele = 16.0%, Table) and similar to published cohorts. Children with two APOL1 G1 alleles had an increased risk of albuminuria that approached statistical significance (p=0.053). Conversely, the presence of the DARC SNP that confers Duffy antigen expression had a protective effect (p=.038). WES analysis did not identify additional non-synonymous APOL1 variants linked with albuminuria. However, 93 non-synonymous variants were associated with DTPA GFR (p<0.001). Using patients with eGFR as a validation cohort, 7 variants in FUBP1, ZFAND4, CD163, GMFG and HLA-E maintained their association with kidney filtrative function (p<0.05). In particular, two variants in CD163, which is a macrophage scavenger receptor for hemoglobin-haptoglobin complexes, were strongly associated with increased GFR in both patient cohorts. Table 1. Candidate genes associated with microalbuminuria. All SNPs were tested with either an additive or recessive genetic model. *The eNOS VNTR was analyzed by the chi-square method. Gene SNP Location MAF Albuminuria (Additive) Variant frequency Cases Controls APOL1 G1 rs73885319 22q12 21.9% 0.053 32.0% 20.3% APOL1 G2 rs71785313 22q12 16.0% 0.445 10.0% 16.0% DARC rs2814778 1q23 13.6% 0.038 4.2% 15.7% eNOS 4a VNTR 7q35 31.2% 0.333* 31.5% 22.7% eNOS rs1799983 7q35 12.5% 0.663 14.6% 12.2% eNOS rs2070744 7q35 15.6% 0.299 10.4% 16.3% CUBN rs7918972 10p12 16.2% 0.457 12.5% 16.8% CUBN rs1801239 10p12 2.7% 0.199 0.0% 3.1% Conclusion: Genetic polymorphisms associated with chronic kidney disease in African American adults may influence the development of early-onset albuminuria among children with SCA, including an increased risk among children with ≥1 APOL1 G1 alleles and a decreased risk associated with the DARC SNP. Previously published eNOS and CUBN variants had no measureable effects. WES analysis suggests novel genetic variants including CD163 SNPs may influence the development of elevated GFR in children with SCA, and provide candidate genes for future research. Disclosures Off Label Use: Hydroxyurea is FDA approved for the treatment of sickle cell anemia in adults, but has not yet been approved in children. . Nottage:Janssen Pharmaceuticals: Employment. Ware:Biomedomics: Research Funding; Bristol Myers Squibb: Research Funding; Bayer Pharmaceuticals: Consultancy; Eli Lilly: Other: DSMB membership

Genetic Modifiers of White Blood Cell Count, Albuminuria and Glomerular Filtration Rate in Children with Sickle Cell Anemia

<div><p>Discovery and validation of genetic variants that influence disease severity in children with sickle cell anemia (SCA) could lead to early identification of high-risk patients, better screening strategies, and intervention with targeted and preventive therapy. We hypothesized that newly identified genetic risk factors for the general African American population could also impact laboratory biomarkers known to contribute to the clinical disease expression of SCA, including variants influencing the white blood cell count and the development of albuminuria and abnormal glomerular filtration rate. We first investigated candidate genetic polymorphisms in well-characterized SCA pediatric cohorts from three prospective NHLBI-supported clinical trials: HUSTLE, SWiTCH, and TWiTCH. We also performed whole exome sequencing to identify novel genetic variants, using both a discovery and a validation cohort. Among candidate genes, <i>DARC</i> rs2814778 polymorphism regulating Duffy antigen expression had a clear influence with significantly increased WBC and neutrophil counts, but did not affect the maximum tolerated dose of hydroxyurea therapy. The <i>APOL1</i> G1 polymorphism, an identified risk factor for non-diabetic renal disease, was associated with albuminuria. Whole exome sequencing discovered several novel variants that maintained significance in the validation cohorts, including <i>ZFHX4</i> polymorphisms affecting both the leukocyte and neutrophil counts, as well as <i>AGGF1</i>, <i>CYP4B1</i>, <i>CUBN</i>, <i>TOR2A</i>, <i>PKD1L2</i>, and <i>CD163</i> variants affecting the glomerular filtration rate. The identification of robust, reliable, and reproducible genetic markers for disease severity in SCA remains elusive, but new genetic variants provide avenues for further validation and investigation.</p></div

Genetic variants identified by WES associated with either WBC or ANC.

<p>Genetic variants identified by WES associated with either WBC or ANC.</p

Coding variants associated with glomerular filtration rate.

<p>Coding variants associated with glomerular filtration rate.</p

Association of candidate genes with WBC and ANC.

<p>Association of candidate genes with WBC and ANC.</p