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Articles by P Hoffmann
Total Records ( 3 ) for P Hoffmann
  L Shi , T Remer , A. E Buyken , M. F Hartmann , P Hoffmann and S. A. Wudy

Whether prepubertal estrogen production impacts on the timing of puberty is not clear. We aimed to investigate prepubertal 24-h estrogen excretion levels and their association with early and late pubertal markers. Daily urinary excretion rates of estrogens of 132 healthy children, who provided 24-h urine samples 1 and 2 yr before the start of the pubertal growth spurt [age at takeoff (ATO)], were quantified by stable isotope dilution/GC-MS. E-sum3 (estrone + estradiol + estriol) was used as a marker for potentially bioactive estrogen metabolites and E-sum5 (E-sum3 + 16-epiestriol + 16-ketoestradiol) for total estrogen production. Pubertal outcomes were ATO, age at peak height velocity (APHV), duration of pubertal growth acceleration (APHV-ATO), age at Tanner stage 2 for pubic hair (PH2), genital (G2, boys) and breast (B2, girls) development, and age at menarche. Prepubertal urinary estrogen excretions (E-sum3 and E-sum5) were not associated with ATO, APHV, and age at PH2 but with duration of pubertal growth acceleration (P < 0.01) in both sexes. Girls with higher E-sum3 reached B2 0.9 yr (P = 0.04) and menarche 0.3 yr earlier (P = 0.04) than girls with lower E-sum3. E-sum3 was not associated with age at G2 in boys (P = 0.6). For most pubertal variables, the associations with E-sum3 were stronger than with E-sum5. In conclusion, prepubertal estrogens may not be critical for the onset of the pubertal growth spurt but are correlated with its duration in both boys and girls. Prepubertal estrogen levels may already predict the timing of girls' menstruation and breast development but do not appear to affect sexual maturation in boys.

  C Schmidl , M Klug , T. J Boeld , R Andreesen , P Hoffmann , M Edinger and M. Rehli

DNA methylation participates in establishing and maintaining chromatin structures and regulates gene transcription during mammalian development and cellular differentiation. With few exceptions, research thus far has focused on gene promoters, and little is known about the extent, functional relevance, and regulation of cell type-specific DNA methylation at promoter-distal sites. Here, we present a comprehensive analysis of differential DNA methylation in human conventional CD4+ T cells (Tconv) and CD4+CD25+ regulatory T cells (Treg), cell types whose differentiation and function are known to be controlled by epigenetic mechanisms. Using a novel approach that is based on the separation of a genome into methylated and unmethylated fractions, we examined the extent of lineage-specific DNA methylation across whole gene loci. More than 100 differentially methylated regions (DMRs) were identified that are present mainly in cell type-specific genes (e.g., FOXP3, IL2RA, CTLA4, CD40LG, and IFNG) and show differential patterns of histone H3 lysine 4 methylation. Interestingly, the majority of DMRs were located at promoter-distal sites, and many of these areas harbor DNA methylation-dependent enhancer activity in reporter gene assays. Thus, our study provides a comprehensive, locus-wide analysis of lineage-specific methylation patterns in Treg and Tconv cells, links cell type-specific DNA methylation with histone methylation and regulatory function, and identifies a number of cell type-specific, CpG methylation-sensitive enhancers in immunologically relevant genes.

  J Schumacher , G Laje , R. A Jamra , T Becker , T. W Muhleisen , C Vasilescu , M Mattheisen , S Herms , P Hoffmann , A. M Hillmer , A Georgi , C Herold , T. G Schulze , P Propping , M Rietschel , F. J McMahon , M. M Nothen and S. Cichon

Association studies, as well as the initial translocation family study, identified the gene Disrupted-In-Schizophrenia-1 (DISC1) as a risk factor for schizophrenia. DISC1 encodes a multifunctional scaffold protein involved in neurodevelopmental processes implicated in the etiology of schizophrenia. The present study explores the contribution of the DISC locus to schizophrenia using three different approaches: (i) systematic association mapping aimed at detecting DISC risk variants in a schizophrenia sample from a central European population (556 SNPs, n = 1621 individuals). In this homogenous sample, a circumscribed DISC1 interval in intron 9 was significantly associated with schizophrenia in females (P = 4 x 10–5) and contributed most strongly to early-onset cases (P = 9 x 10–5). The odds ratios (ORs) were in the range of 1.46–1.88. (ii) The same sample was used to test for the locus-specific SNP–SNP interaction most recently associated with schizophrenia. Our results confirm the SNP interplay effect between rs1538979 and rs821633 that significantly conferred disease risk in male patients with schizophrenia (P = 0.016, OR 1.57). (iii) In order to detect additional schizophrenia variants, a meta-analysis was performed using nine schizophrenia samples from different European populations (50 SNPs, n = 10 064 individuals maximum, n = 3694 minimum). We found evidence for a common schizophrenia risk interval within DISC1 intron 4–6 (P = 0.002, OR 1.27). The findings point to a complex association between schizophrenia and DISC, including the presence of different risk loci and SNP interplay effects. Furthermore, our phenotype–genotype results—including the consideration of sex-specific effects—highlight the value of homogenous samples in mapping risk genes for schizophrenia in general, and at the DISC locus in particular.

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