| 1. |
- Willer, Cristen J., et al.
(author)
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Six new loci associated with body mass index highlight a neuronal influence on body weight regulation
- 2009
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 41:1, s. 25-34
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Journal article (peer-reviewed)abstract
- Common variants at only two loci, FTO and MC4R, have been reproducibly associated with body mass index (BMI) in humans. To identify additional loci, we conducted meta-analysis of 15 genome-wide association studies for BMI (n > 32,000) and followed up top signals in 14 additional cohorts (n > 59,000). We strongly confirm FTO and MC4R and identify six additional loci (P < 5 x 10(-8)): TMEM18, KCTD15, GNPDA2, SH2B1, MTCH2 and NEGR1 (where a 45-kb deletion polymorphism is a candidate causal variant). Several of the likely causal genes are highly expressed or known to act in the central nervous system (CNS), emphasizing, as in rare monogenic forms of obesity, the role of the CNS in predisposition to obesity.
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| 2. |
- Lindgren, Cecilia M, et al.
(author)
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Genome-wide association scan meta-analysis identifies three Loci influencing adiposity and fat distribution.
- 2009
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In: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 5:6, s. e1000508-
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Journal article (peer-reviewed)abstract
- To identify genetic loci influencing central obesity and fat distribution, we performed a meta-analysis of 16 genome-wide association studies (GWAS, N = 38,580) informative for adult waist circumference (WC) and waist-hip ratio (WHR). We selected 26 SNPs for follow-up, for which the evidence of association with measures of central adiposity (WC and/or WHR) was strong and disproportionate to that for overall adiposity or height. Follow-up studies in a maximum of 70,689 individuals identified two loci strongly associated with measures of central adiposity; these map near TFAP2B (WC, P = 1.9x10(-11)) and MSRA (WC, P = 8.9x10(-9)). A third locus, near LYPLAL1, was associated with WHR in women only (P = 2.6x10(-8)). The variants near TFAP2B appear to influence central adiposity through an effect on overall obesity/fat-mass, whereas LYPLAL1 displays a strong female-only association with fat distribution. By focusing on anthropometric measures of central obesity and fat distribution, we have identified three loci implicated in the regulation of human adiposity.
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| 3. |
- Laukkanen, P., et al.
(author)
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Anomalous bismuth-stabilized (2x1) reconstructions on GaAs(100) and InP(100) surfaces
- 2008
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 100, s. 086101-
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Journal article (peer-reviewed)abstract
- First-principles phase diagrams of bismuth-stabilized GaAs- and InP(100) surfaces demonstrate for the first time the presence of anomalous (2 x 1) reconstructions, which disobey the common electron counting principle. Combining these theoretical results with our scanning-tunneling-microscopy and photoemission measurements, we identify novel (2 x 1) surface structures, which are composed of symmetric Bi-Bi and asymmetric mixed Bi-As and Bi-P dimers, and find that they are stabilized by stress relief and pseudogap formation.
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| 4. |
- Punkkinen, M. P. J., et al.
(author)
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Bismuth-stabilized (2x1) and (2x4) reconstructions on GaAs(100) surfaces : Combined first-principles, photoemission, and scanning tunneling microscopy study
- 2008
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 78, s. 195304-
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Journal article (peer-reviewed)abstract
- Bismuth adsorbate-stabilized (2x1) and (2x4) reconstructions of the GaAs(100) surfaces have been studied by first-principles calculations, valence-band and core-level photoelectron spectroscopies, and scanning tunneling microscopy. It is demonstrated that large Bi atom size leads to the formation of the pseudogap at the Fermi energy and to the lower energy of an adsorbate-derived surface band, which contributes to the stabilization of the exceptional Bi/GaAs(100)(2x1) reconstruction. It is proposed that the Bi/GaAs(100)(2x4) reconstructions include asymmetric mixed Bi-As dimers, in addition to the Bi-Bi dimers. Based on the calculations, we solve the atomic origins of the surface core-level shifts (SCLSs) of the Bi 5d photoemission spectra from the Bi/GaAs(100)(2x4) surfaces. This allows for resolving the puzzle related to the identification of two SCLS components often found in the measurements of the Bi 5d and Sb 4d core-level emissions of the Bi/III-V and Sb/III-V(100)(2x4) surfaces. Finally, the reason for the absence of the common (2x4)-beta 2 structure and additional support for the stability of the (2x1) structure on the Bi/III-V(100) surfaces are discussed in terms of Bi atom size and subsurface stress.
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| 5. |
- Punkkinen, M. P. J., et al.
(author)
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Surface core-level shifts of GaAs(100)(2x4) from first principles
- 2007
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 76:11
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Journal article (peer-reviewed)abstract
- First-principles calculations show that measured surface core-level shifts (SCLSs) of the GaAs(100)(2x4) surfaces can be described within the initial state effects. The calculated As 3d and Ga 3d SCLSs for the beta 2 and alpha 2 reconstructions of the GaAs(100)(2x4) surfaces are in reasonable agreement with recent measurements. In particular, the results confirm that both the lower and the higher binding energy SCLSs, relative to the bulk emission in the As 3d photoelectron spectra, are intrinsic properties of the GaAs(100)(2x4) surfaces. The most positive and most negative As shifts are attributed to the third layer As atoms, which differs from the previous intuitive suggestions. In general, calculations show that significant SCLSs arise from deep layers, and that there are more than two SCLSs. Our previously measured As 3d spectra are fitted afresh using the calculated SCLSs. The intensity ratios of the SCLSs, obtained from the fits, show that as the heating temperature of the GaAs(100)(2x4) surface is increased gradually, the area of the alpha 2 reconstruction increases on the surface, but the beta 2 phase remains within the whole temperature range, in agreement with previous experimental findings. Our results show that the combination of the experimental and theoretical results is a prerequisite for the accurate analysis of the SCLSs of the complex reconstructed surfaces.
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| 6. |
- Zeggini, Eleftheria, et al.
(author)
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Meta-analysis of genome-wide association data and large-scale replication identifies additional susceptibility loci for type 2 diabetes
- 2008
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 40:5, s. 638-645
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Journal article (peer-reviewed)abstract
- Genome-wide association (GWA) studies have identified multiple loci at which common variants modestly but reproducibly influence risk of type 2 diabetes (T2D)(1-11). Established associations to common and rare variants explain only a small proportion of the heritability of T2D. As previously published analyses had limited power to identify variants with modest effects, we carried out meta-analysis of three T2D GWA scans comprising 10,128 individuals of European descent and similar to 2.2 million SNPs (directly genotyped and imputed), followed by replication testing in an independent sample with an effective sample size of up to 53,975. We detected at least six previously unknown loci with robust evidence for association, including the JAZF1 (P=5.0 x 10(-14)), CDC123-CAMK1D (P=1.2 x 10(-10)), TSPAN8-LGR5 (P=1.1 x 10(-9)), THADA (P=1.1 x 10(-9)), ADAMTS9 (P=1.2 x 10(-8)) and NOTCH2 (P=4.1 x 10(-8)) gene regions. Our results illustrate the value of large discovery and follow-up samples for gaining further insights into the inherited basis of T2D.
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| 7. |
- Laukkanen, P., et al.
(author)
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A comparative study of clean and Bi-stabilized InP(100)(2 x 4) surfaces by the core-level photoelectron spectroscopy
- 2007
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In: Surface Science. - : Elsevier BV. - 0039-6028. ; 601, s. 3395-
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Journal article (peer-reviewed)abstract
- The bismuth-stabilized (2 x 4)-reconstructed InP(100) surface [Bi/InP(100)(2 x 4)] has been studied by synchrotron-radiation core-level photoelectron spectroscopy. The spectra are compared with previous core-level data obtained on a clean InP(100)(2 x 4) surface. The findings support that the P 2p surface-core-level shift (SCLS) of the clean InP(100)(2 x 4), which has higher kinetic energy than the bulk emission, arises from the third-layer P atoms and that the second P 2p SCLS, which has lower kinetic energy than the bulk, arises from the top-layer P atoms. Similar In 4d SCLSs are found on the clean and Bi-stabilized InP(100)(2 x 4) surfaces, indicating that these shifts contain contributions of the In atoms that lie in the second and/or fourth layers. In addition to this, the results improve our understanding of the atomic structure of the Bi/InP(100)(2 x 4) surface and lead to refined surface models which include Bi-Bi and Bi-P dimers. (C) 2007 Elsevier B.V. All rights reserved.
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| 8. |
- Prokopenko, Inga, et al.
(author)
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Variants in MTNR1B influence fasting glucose levels
- 2009
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 41:1, s. 77-81
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Journal article (peer-reviewed)abstract
- To identify previously unknown genetic loci associated with fasting glucose concentrations, we examined the leading association signals in ten genome-wide association scans involving a total of 36,610 individuals of European descent. Variants in the gene encoding melatonin receptor 1B (MTNR1B) were consistently associated with fasting glucose across all ten studies. The strongest signal was observed at rs10830963, where each G allele (frequency 0.30 in HapMap CEU) was associated with an increase of 0.07 (95% CI = 0.06-0.08) mmol/l in fasting glucose levels (P = 3.2 x 10(-50)) and reduced beta-cell function as measured by homeostasis model assessment (HOMA-B, P = 1.1 x 10(-15)). The same allele was associated with an increased risk of type 2 diabetes (odds ratio = 1.09 (1.05-1.12), per G allele P = 3.3 x 10(-7)) in a meta-analysis of 13 case-control studies totaling 18,236 cases and 64,453 controls. Our analyses also confirm previous associations of fasting glucose with variants at the G6PC2 (rs560887, P = 1.1 x 10(-57)) and GCK (rs4607517, P = 1.0 x 10(-25)) loci.
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| 9. |
- Punkkinen, M. P. J., et al.
(author)
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Calculation of surface core-level shifts within complete screening : Problems with pseudohydrogenated slabs
- 2008
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 77:24
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Journal article (peer-reviewed)abstract
- By considering GaAs(110) and Si(100)(2x1) surfaces, it is shown that the use of the pseudohydrogen atoms to saturate the dangling bonds at one side of the slab modeling a free surface can lead to distorted surface core-level shifts within the complete screening picture. The effect is linked to the polarization of the slab and to the change in the bulklike electronic structure close to pseudohydrogenated part of the slab. It is demonstrated that these problems can be avoided if the pseudohydrogenated slab is large enough and the bulk reference layer is properly chosen. One easy way to control these errors is to monitor the planar-averaged potential energy curve of the slab.
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| 10. |
- Punkkinen, Marko P. J., et al.
(author)
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Core-level shifts of InP(100)(2 x 4) surface : Theory and experiment
- 2009
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In: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 603:16, s. 2664-2668
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Journal article (peer-reviewed)abstract
- Surface core-level shifts (SCLSs) of the (2 x 4)-reconstructed InP(100) surface with the established mixed In-P dimer structure have been investigated by first-principles calculations and photoelectron spectroscopy. Theoretical values were calculated using both the local density approximation (LDA) and the generalized gradient approximation (GGA) for the exchange-correlation energy functional. The obtained theoretical values are quite similar within both approximations. The found differences originate in the tiny structural differences. It is concluded that the expansion or contraction of the crystal lattice has smaller effect on the SCLSs than the geometrical details of the reconstruction, which suggests that the Madelung potential has the dominant effect on the SCLSs. The results support the presence of a P 2p peak at higher binding energy (BE) compared to bulk peak, as proposed with recent measurements [P. Laukkamen, J. Pakarinen, M. Ahola-Tuomi, M. Kuzmin, R. E. Perala, I. J. Vayrynen, A. Tukiainen, V. Rimpilainen, M. Pessa, M. Adell, J. Sadowski, Surf. Sci. 600 (2006) 3022], and reveal several hitherto not reported SCLSs. The calculated SCLSs reproduce the measured spectra within reasonable accuracy. Furthermore, the atomic origins of the InP(100)(2 x 4) SCLSs are solved. In particular, it is shown that the lowest SCLS of P 2p, of the InP(100)(2 x 4) arises from the topmost In-P dimers.
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