Genetic polymorphisms in lung disease: bandwagon or breakthrough?

The study of genetic polymorphisms has touched every aspect of pulmonary and critical care medicine. We review recent progress made using genetic polymorphisms to define pathophysiology, to identify persons at risk for pulmonary disease and to predict treatment response. Several pitfalls are commonly encountered in studying genetic polymorphisms, and this article points out criteria that should be applied to design high-quality genetic polymorphism studies

Properties of the lectin from the hog peanut (Amphicarpaea bracteata)

An N-acetyl--galactosamine-specific lectin has been isolated from the two seed forms of the hog peanut (Amphicarpaea bracteata) using an affinity support containing the synthetic type A blood group trisaccharide [alpha]--GalNAc-(1,3)-[[alpha]--Fuc-(1,2)]-[beta]--Gal (Synsorb A). The affinity-purified lectin appears to be identical in both seed types. Gel filtration on Sephadex G-200 gives a single symmetrical peak corresponding to Mr 135,000. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis shows four subunit forms, each of which contains carbohydrate. Limited amino terminal sequencing indicates heterogeneity in two of the first 10 residues. The lectin contains no cysteine. There are four equivalent, noninteracting GalNAc binding sites per 135,000-Da molecule, having an association constant for methyl N-acetyl-[alpha]--galactosaminide of 4.0 x 104 -1. Precipitin and hapten inhibition studies show the lectin to be specific for terminal, nonreducing -GalNAc units, with a preference for the [alpha]-anomer and enhanced specificity for the disaccharide, GalNAc[alpha]1,3GalNAc. There is also a single adenine binding site per Mr 135,000 lectin molecule with an association constant of 1.3 x 106 -1.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26701/1/0000249.pd

Studies On The Structural And Ligand Binding Properties Of N -acetylgalactosamine Specific Lectins.

The nature and structure of the adenine, carbohydrate and metal binding sites in legume lectins was investigated. The interaction of a spin-labeled analog of adenine, N\sp6 -(2,2,6,6-tetramethyl-piperidin-1-oxy-4-yl)-adenine with several lectins was studied. Electron spin resonance (ESR) showed the ligand nitroxyl group to be strongly immobilized by the lectins from Phaseolus vulgaris (PHA-E and L), lima bean, and Dolichos biflorus. The analog appeared to bind at an additional secondary site on PHA-E and lima bean lectin (LBL). Spin-labeled adenine binding was unaffected by addition of EDTA on N-acetyl- sc D-galactosamine. The distance between the nitroxyl moieties of spin-labeled adenine and spin-labeled sc D-GalNAc bound to LBL is $>$12 A. The pH-dependence of adenine binding to LBL, PHA-E, and soybean agglutinin revealed very broad profiles, with approximate pH optima between 5.5 and 7.4. The temperature dependence of adenine binding to LBL yielded thermodynamic values which suggest that binding of adenine to LBL is dominated by van der Waals or hydrogen bonding interactions rather than hydrophobic or ionic interactions. Neither metal chelators nor reduction of thiols with dithiothreitol affected adenine binding. 8-Azidoadenine was employed as a photoaffinity probe of LBL and PHA-E. This compound bound competetively to the adenine site of each lectin. Enhanced binding occurred in the presence of ANS. Amino acid sequences of labeled tryptic peptides isolated from LBL and PHA-E overlapped by five amino acid residues. Antibodies were raised against a synthetic peptide whose sequence corresponds to an LBL peptide containing a cysteine residue essential for carbohydrate binding. All antisera cross-reacted with several proteolyzed legume lectins; one reacted with several intact lectins. Results suggest a metal and/or carbohydrate binding region exposed to solvent, and accessible to the immunoglobulin combining site. The synthetic undecapeptide and favin peptide showed distinctive ultraviolet difference spectra upon binding Ca\sp{2+}. A sc D-GalNAc-specific lectin from the two seed forms of Amphicarpaea bracteata was characterized. Precipitin inhibition studies indicate the lectin to be specific for terminal, nonreducing sc D-GalNAc units with a preference for the anomer and enhanced specificity for the disaccharide, GalNAc$\alpha$1,3GalNAc. The lectin has four GalNAc sites and a single adenine binding site per molecule.Ph.D.BiochemistryPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/128112/2/8801366.pd

The BTNL2 Gene and Sarcoidosis Susceptibility in African Americans and Whites

The BTNL2 gene is a member of the B7 receptor family that probably functions as a T-cell costimulatory molecule. It resides in the class II major histocompatibility complex (MHC) region of chromosome 6p and has recently been associated with sarcoidosis susceptibility in a white German population. We sought to replicate the BTNL2 association in an African American family-based study population (n=219 nuclear families) and two case-control populations—one African American (n=295 pairs) and one white (n=366 pairs). Ten SNPs were detected within a 490-bp region spanning exon/intron 5 of BTNL2. Haplotype variation within this region was significantly associated with sarcoidosis in all three study populations but more so in whites (P=.0006) than in the African American case-control (P=.02) or family-based (P=.03) samples. The previously reported BTNL2 SNP with the strongest sarcoidosis association, rs2076530, was also the SNP with the strongest association in our white population (P<.0001). The A allele of rs2076530 results in a premature exon-splice site and increases risk for sarcoidosis (odds ratio=2.03; 95% confidence interval 1.32–3.12). Although rs2076530 was not associated with sarcoidosis in either African American sample, a three-locus haplotype that included rs2076530 was associated with sarcoidosis across all three study samples. Multivariable logistic regression analyses showed that BTNL2 effects are independent of human leukocyte antigen class II genes in whites but may interact antagonistically in African Americans. Our results underscore the complexity of genetic risk for sarcoidosis emanating from the MHC region

HLA-DRB1*1101: A Significant Risk Factor for Sarcoidosis in Blacks and Whites

Sarcoidosis is a granulomatous disorder of unknown etiology, associated with an accumulation of CD4+ T cells and a TH1 immune response. Since previous studies of HLA associations with sarcoidosis were limited by serologic or low-resolution molecular identification, we performed high-resolution typing for the HLA-DPB1, HLA-DQB1, HLA-DRB1, and HLA-DRB3 loci and the presence of the DRB4 or DRB5 locus, to define HLA class II associations with sarcoidosis. A Case Control Etiologic Study of Sarcoidosis (ACCESS) enrolled biopsy-confirmed cases (736 total) from 10 centers in the United States. Seven hundred six (706) controls were case matched for age, race, sex, and geographic area. We studied the first 474 ACCESS patients and case-matched controls. The HLA-DRB1 alleles were differentially distributed between cases and controls (P<.0001). The HLA-DRB1*1101 allele was associated (P<.01) with sarcoidosis in blacks and whites and had a population attributable risk of 16% in blacks and 9% in whites. HLA-DRB1-F(47) was the amino acid residue most associated with sarcoidosis and independently associated with sarcoidosis in whites. The HLA-DPB1 locus also contributed to susceptibility for sarcoidosis and, in contrast to chronic beryllium disease, a non–E(69)-containing allele, HLA-DPB1*0101, conveyed most of the risk. Although significant differences were observed in the distribution of HLA class II alleles between blacks and whites, only HLA-DRB1*1501 was differentially associated with sarcoidosis (P<.003). In addition to being susceptibility markers, HLA class II alleles may be markers for different phenotypes of sarcoidosis (DRB1*0401 for eye in blacks and whites, DRB3 for bone marrow in blacks, and DPB1*0101 for hypercalcemia in whites). These studies confirm a genetic predisposition for sarcoidosis and present evidence for the allelic variation at the HLA-DRB1 locus as a major contributor