Unrelated donors selected prospectively by block-matching have superior bone marrow transplant outcome

Previous retrospective studies have demonstrated improved outcome in patients whose donors were matched for non-HLA markers in the MHC as well as for HLA genes. Forty patients receiving transplants from unrelated donors were typed prospectively for HLA and non-HLA markers. Non-HLA markers near HLA-B (beta-block markers) and in the DRB1 introns (delta-block markers) were used to assess MHC match between donors and recipient. Patients whose donors were matched at the beta- and delta-blocks had improved event free survival (63%) compared to patients whose donors were mismatched at one or both blocks (25%) (p < 0.05). Patients whose donors were matched at the beta-block had significantly less severe acute graft versus host disease (p < 0.05). In order to investigate the basis for improved outcome block matching was correlated with HLA matching as determined by DNA sequencing. Beta-block matching was highly correlated with matching for exons 2 and 3 of HLA-B but less so for HLA-C. Delta-block matching was highly correlated with matching for exon 2 of HLA DRB1. It is concluded that matching for non-HLA markers in the MHC improves matching for HLA genes. Further studies are required to determine whether matching for non-HLA markers improves outcome to a greater extent than matching for the HLA genes alone.     

No Association between SNP rs498055 on Chromosome 10 and Late-Onset Alzheimer Disease in Multiple Datasets

SNP rs498055 in the predicted gene LOC439999 on chromosome 10 was recently identified as being strongly associated with late-onset Alzheimer disease (LOAD). This SNP falls within a chromosomal region that has engendered continued interest generated from both preliminary genetic linkage and candidate gene studies. To independently evaluate this interesting candidate SNP we examined four independent datasets, three family-based and one case-control. All the cases were late-onset AD Caucasian patients with minimum age at onset ≥ 60 years. None of the three family samples or the combined family-based dataset showed association in either allelic or genotypic family-based association tests at p < 0.05. Both original and OSA two-point LOD scores were calculated. However, there was no evidence indicating linkage no matter what covariates were applied (the highest LOD score was 0.82). The case-control dataset did not demonstrate any association between this SNP and AD (all p-values > 0.52). Our results do not confirm the previous association, but are consistent with a more recent negative association result that used family-based association tests to examine the effect of this SNP in two family datasets. Thus we conclude that rs498055 is not associated with an increased risk of LOAD.     

Hepatitis B virus transmission in Brazilian hemodialysis units: serological and molecular follow-up

A serological and molecular study of hepatitis B virus (HBV) infection was carried out in dialysis units in Central Brazil. Between 1995 and 1999, serum samples from all HBsAg-positive hemodialysis patients (n = 43) were tested for HBeAg/anti-HBe and subtyping by monoclonal ELISA. HBV DNA was detected by PCR and positive samples were genotyped by restriction fragment polymorphism pattern (RFLP) methodology. TheHBsAg prevalence declined in this population during the survey period (12-5.8%). HBeAg and anti-HBe were detected in 23 (53.5%) and 18 (41.9%) sera, respectively. Thirty-six samples could be HBsAg subtyped: 21 were subtype ayw(3), 14 belonged to adw(2) and one was identified as adw(4). HBV DNA was present in 30 serum samples. Of these, 20 (66.7%) were genotype D, 9 (30%) genotype A, and 1 (3.3%) genotype F. In addition, the RFLP pattern could be determined in samples from 18/20 genotype D patients: D3 (10 strains), D7 (7 strains) and D4 (1 strain); from 8/9 genotype A patients: A1 (6 strains) and A3 (2 strains); and from the patient infected with genotype F: F1. Patterns D3 and D7 were associated closely with HBV infection in the two largest hemodialysis units studied. These findings confirm the value of the RFLP method as an effective molecular epidemiological tool for elucidating HBV transmission in hemodialysis units.     

Role of endogenous IFN-gamma in macrophage programming induced by IL-12 and IL-18.

Besides the established role of interleukin-12 (IL-12) and IL-18 on interferon-gamma (IFN-gamma) production by natural killer (NK), T, and B cells, the effects of these cytokines on macrophages are largely unknown. Here, we investigated the role of IL-12/IL-18 on nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) production by CD11b(+) adherent peritoneal cells, focusing on the involvement of endogenously produced IFN-gamma. C57BL/6 cells released substantial amounts of NO when stimulated with IFN-gamma or lipopolysaccharide (LPS), but failed to respond to IL-12 or IL-18 or both. However, IL-12/IL-18 pretreatment was able to program these cells to release 6-8-fold more NO and TNF-alpha in response to LPS or Trypanosoma cruzi stimulation, with NO levels directly correlating with macrophage resistance to intracellular parasite growth. Analysis of IL-12/IL-18-primed cells from mice deficient in IFN-gamma, IFNGR, and IFN regulatory factor-1 (IRF-1) revealed that these molecules were essential for LPS-induced NO release, but TNF-alpha production was IFN-gamma independent. Conversely, the myeloid differentiation factor 88 (MyD88)-dependent pathway was indispensable for IL-12/IL-18-programmed LPS-induced TNF-alpha production, but not for NO release. Contaminant T and NK cells largely modulated the IL-12/IL-18 programming of LPS-induced NO response through IFN-gamma secretion. Nevertheless, a small population of IFN-gamma(+) cells with a macrophage phenotype was also identified, particularly in the peritoneum of chronically T. cruzi-infected mice, reinforcing the notion that macrophages can be an alternative source of IFN-gamma. Taken together, our data contribute to elucidate the molecular basis of the IL-12/IL-18 autocrine pathway of macrophage activation, showing that endogenous IFN-gamma plays an important role in programming the NO response, whereas the TNF-alpha response occurs through an IFN-gamma-independent pathway.     

Three distinct loci on human chromosome 21 contribute to interferon-α/β responsiveness

The species specificity of interferons (IFNs) depends on restricted recognition of these ligands by multisubunit cell surface receptors. Expression of the human receptor subunit IFNAR in mouse cells conferred sensitivity only to one subtype of human IFN, IFN-B. Other genes on human chromosome 21 were required for responses to other subtypes of type I IFN. In contrast, IFNAR expression in hamster cells did not confer sensitivity to any human IFN tested, including IFN-B. Using human-hamster somatic cell hybrids, we mapped theIfnabr gene, encoding a ligand-binding subunit of the IFN-/ (type I) receptor, to human chromosome 21.Ifnabr colocalized withIfnar to the distal region of q22.1. The presence of a chromosomal fragment encoding IFNABR and IFNAR was also not sufficient to confer sensitivity to human IFN. In contrast, hybrids carrying in addition the region 21q22.2 showed a full response to human IFN-B, suggesting that a gene located in this region encodes a third factor required for type I IFN receptor activity.     

Comparison of DNA- and RNA-based methods for detection of truncating BRCA1 mutations

A number of methods are used for mutational analysis of BRCA1, a large multi-exon gene. A comparison was made of five methods to detect mutations generating premature stop codons that are predicted to result in synthesis of a truncated protein in BRCA1. These included four DNA-based methods: two-dimensional gene scanning (TDGS), denaturing high performance liquid chromatography (DHPLC), enzymatic mutation detection (EMD), and single strand conformation polymorphism analysis (SSCP) and an RNA/DNA-based protein truncation test (PTT) with and without complementary 5' sequencing. DNA and RNA samples isolated from 21 coded lymphoblastoid cell line samples were tested. These specimens had previously been analyzed by direct automated DNA sequencing, considered to be the optimum method for mutation detection. The set of 21 cell lines included 14 samples with 13 unique frameshift or nonsense mutations, three samples with two unique splice site mutations, and four samples without deleterious mutations. The present study focused on the detection of protein-truncating mutations, those that have been reported most often to be disease-causing alterations that segregate with cancer in families. PTT with complementary 5' sequencing correctly identified all 15 deleterious mutations. Not surprisingly, the DNA-based techniques did not detect a deletion of exon 22. EMD and DHPLC identified all of the mutations with the exception of the exon 22 deletion. Two mutations were initially missed by TDGS, but could be detected after slight changes in the test design, and five truncating mutations were missed by SSCP. It will continue to be important to use complementary methods for mutational analysis.     

Microbial exposure of rural school children, as assessed by levels of N-acetyl-muramic acid in mattress dust, and its association with respiratory health

BACKGROUND: Endotoxin exposure has been shown to be associated with a decreased prevalence of atopic sensitization and symptoms. Yet endotoxin represents only a part of the indoor microbial exposure. Muramic acid, a constituent of peptidoglycan, is present in gram-negative and gram-positive bacteria in the environment and may therefore serve as an additional marker of microbial exposure. OBJECTIVE: To study the factors determining the level of indoor exposure to muramic acid/peptidoglycan, as well as its potential association with respiratory health. METHODS: In 553 farm and nonfarm school children from Austria, Switzerland, and Germany, mattress dust muramic acid concentrations were determined, and health was assessed by using IgE measurements and questionnaire information. RESULTS: The muramic acid concentration was found to be significantly higher in dust from farm children's mattresses than in dust from nonfarm children's mattresses (157 vs 131 ng/mg). Children with higher mattress dust muramic acid concentrations had a significantly lower prevalence of wheezing (odds ratio of highest vs lowest tertile of muramic acid concentration, 0.3; 95% CI, 0.1-0.9), regardless of farming status and endotoxin exposure. The association for asthma was similar, and no association was found with atopic sensitization. CONCLUSION: Next to endotoxin, muramic acid provides us with an independent marker of microbial exposure. Unlike endotoxin, muramic acid was inversely associated with wheezing rather than with atopic sensitization.     

Metabolic polymorphisms and the micronucleus frequency in buccal epithelium of adolescents living in an urban environment

Micronuclei and other biomarkers were evaluated in oral cells from 11- to 16-year-old girls living in a foster home in the central area of México City. Variables analyzed for possible association with these biomarkers include smoking habits, body mass index, metabolic polymorphisms for NAT1 and GSTM1 and whether the cells were obtained from the cheek or pharynx. The results indicated that individuals having the NAT1*10 homozygous genotype showed a significant increase in chromatin buds and binucleated cells. When the damage in the cheek was compared with damage in the pharynx, a significant increase in micronuclei and binucleated cells was found for the latter tissue in all the individuals analyzed.