| 1. |
- Ackermann, M., et al.
(författare)
-
Periodic Emission from the Gamma-Ray Binary 1FGL J1018.6-5856
- 2012
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 335:6065, s. 189-193
-
Tidskriftsartikel (refereegranskat)abstract
- Gamma-ray binaries are stellar systems containing a neutron star or black hole, with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6-day period. We identified a variable x-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.
|
|
| 2. |
|
|
| 3. |
- Palmer, Nicholette D, et al.
(författare)
-
A genome-wide association search for type 2 diabetes genes in African Americans.
- 2012
-
Ingår i: PloS one. - San Francisco : Public Library of Science (PLoS). - 1932-6203. ; 7:1, s. e29202-
-
Tidskriftsartikel (refereegranskat)abstract
- African Americans are disproportionately affected by type 2 diabetes (T2DM) yet few studies have examined T2DM using genome-wide association approaches in this ethnicity. The aim of this study was to identify genes associated with T2DM in the African American population. We performed a Genome Wide Association Study (GWAS) using the Affymetrix 6.0 array in 965 African-American cases with T2DM and end-stage renal disease (T2DM-ESRD) and 1029 population-based controls. The most significant SNPs (n = 550 independent loci) were genotyped in a replication cohort and 122 SNPs (n = 98 independent loci) were further tested through genotyping three additional validation cohorts followed by meta-analysis in all five cohorts totaling 3,132 cases and 3,317 controls. Twelve SNPs had evidence of association in the GWAS (P<0.0071), were directionally consistent in the Replication cohort and were associated with T2DM in subjects without nephropathy (P<0.05). Meta-analysis in all cases and controls revealed a single SNP reaching genome-wide significance (P<2.5×10(-8)). SNP rs7560163 (P = 7.0×10(-9), OR (95% CI) = 0.75 (0.67-0.84)) is located intergenically between RND3 and RBM43. Four additional loci (rs7542900, rs4659485, rs2722769 and rs7107217) were associated with T2DM (P<0.05) and reached more nominal levels of significance (P<2.5×10(-5)) in the overall analysis and may represent novel loci that contribute to T2DM. We have identified novel T2DM-susceptibility variants in the African-American population. Notably, T2DM risk was associated with the major allele and implies an interesting genetic architecture in this population. These results suggest that multiple loci underlie T2DM susceptibility in the African-American population and that these loci are distinct from those identified in other ethnic populations.
|
|
| 4. |
- Voight, Benjamin F., et al.
(författare)
-
Twelve type 2 diabetes susceptibility loci identified through large-scale association analysis
- 2010
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 42:7, s. 579-589
-
Tidskriftsartikel (refereegranskat)abstract
- By combining genome-wide association data from 8,130 individuals with type 2 diabetes (T2D) and 38,987 controls of European descent and following up previously unidentified meta-analysis signals in a further 34,412 cases and 59,925 controls, we identified 12 new T2D association signals with combined P < 5 x 10(-8). These include a second independent signal at the KCNQ1 locus; the first report, to our knowledge, of an X-chromosomal association (near DUSP9); and a further instance of overlap between loci implicated in monogenic and multifactorial forms of diabetes (at HNF1A). The identified loci affect both beta-cell function and insulin action, and, overall, T2D association signals show evidence of enrichment for genes involved in cell cycle regulation. We also show that a high proportion of T2D susceptibility loci harbor independent association signals influencing apparently unrelated complex traits.
|
|
| 5. |
- Saxena, Richa, et al.
(författare)
-
Genetic variation in GIPR influences the glucose and insulin responses to an oral glucose challenge
- 2010
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 42:2, s. 142-148
-
Tidskriftsartikel (refereegranskat)abstract
- Glucose levels 2 h after an oral glucose challenge are a clinical measure of glucose tolerance used in the diagnosis of type 2 diabetes. We report a meta-analysis of nine genome-wide association studies (n = 15,234 nondiabetic individuals) and a follow-up of 29 independent loci (n = 6,958–30,620). We identify variants at the GIPR locus associated with 2-h glucose level (rs10423928, β (s.e.m.) = 0.09 (0.01) mmol/l per A allele, P = 2.0 × 10−15). The GIPR A-allele carriers also showed decreased insulin secretion (n = 22,492; insulinogenic index, P = 1.0 × 10−17; ratio of insulin to glucose area under the curve, P = 1.3 × 10−16) and diminished incretin effect (n = 804; P = 4.3 × 10−4). We also identified variants at ADCY5 (rs2877716, P = 4.2 × 10−16), VPS13C (rs17271305, P = 4.1 × 10−8), GCKR (rs1260326, P = 7.1 × 10−11) and TCF7L2 (rs7903146, P = 4.2 × 10−10) associated with 2-h glucose. Of the three newly implicated loci (GIPR, ADCY5 and VPS13C), only ADCY5 was found to be associated with type 2 diabetes in collaborating studies (n = 35,869 cases, 89,798 controls, OR = 1.12, 95% CI 1.09–1.15, P = 4.8 × 10−18).
|
|
| 6. |
- Scott, Robert A, et al.
(författare)
-
No interactions between previously associated 2-hour glucose gene variants and physical activity or BMI on 2-hour glucose levels
- 2012
-
Ingår i: Diabetes. - Alexandria, VA : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 61:5, s. 1291-1296
-
Tidskriftsartikel (refereegranskat)abstract
- Gene-lifestyle interactions have been suggested to contribute to the development of type 2 diabetes. Glucose levels 2 h after a standard 75-g glucose challenge are used to diagnose diabetes and are associated with both genetic and lifestyle factors. However, whether these factors interact to determine 2-h glucose levels is unknown. We meta-analyzed single nucleotide polymorphism (SNP) × BMI and SNP × physical activity (PA) interaction regression models for five SNPs previously associated with 2-h glucose levels from up to 22 studies comprising 54,884 individuals without diabetes. PA levels were dichotomized, with individuals below the first quintile classified as inactive (20%) and the remainder as active (80%). BMI was considered a continuous trait. Inactive individuals had higher 2-h glucose levels than active individuals (β = 0.22 mmol/L [95% CI 0.13-0.31], P = 1.63 × 10(-6)). All SNPs were associated with 2-h glucose (β = 0.06-0.12 mmol/allele, P ≤ 1.53 × 10(-7)), but no significant interactions were found with PA (P > 0.18) or BMI (P ≥ 0.04). In this large study of gene-lifestyle interaction, we observed no interactions between genetic and lifestyle factors, both of which were associated with 2-h glucose. It is perhaps unlikely that top loci from genome-wide association studies will exhibit strong subgroup-specific effects, and may not, therefore, make the best candidates for the study of interactions.
|
|
| 7. |
|
|
| 8. |
- Dimas, Antigone S, et al.
(författare)
-
Impact of type 2 diabetes susceptibility variants on quantitative glycemic traits reveals mechanistic heterogeneity.
- 2014
-
Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 63:6, s. 2158-2171
-
Tidskriftsartikel (refereegranskat)abstract
- Patients with established type 2 diabetes display both beta-cell dysfunction and insulin resistance. To define fundamental processes leading to the diabetic state, we examined the relationship between type 2 diabetes risk variants at 37 established susceptibility loci and indices of proinsulin processing, insulin secretion and insulin sensitivity. We included data from up to 58,614 non-diabetic subjects with basal measures, and 17,327 with dynamic measures. We employed additive genetic models with adjustment for sex, age and BMI, followed by fixed-effects inverse variance meta-analyses. Cluster analyses grouped risk loci into five major categories based on their relationship to these continuous glycemic phenotypes. The first cluster (PPARG, KLF14, IRS1, GCKR) was characterized by primary effects on insulin sensitivity. The second (MTNR1B, GCK) featured risk alleles associated with reduced insulin secretion and fasting hyperglycemia. ARAP1 constituted a third cluster characterized by defects in insulin processing. A fourth cluster (including TCF7L2, SLC30A8, HHEX/IDE, CDKAL1, CDKN2A/2B) was defined by loci influencing insulin processing and secretion without detectable change in fasting glucose. The final group contained twenty risk loci with no clear-cut associations to continuous glycemic traits. By assembling extensive data on continuous glycemic traits, we have exposed the diverse mechanisms whereby type 2 diabetes risk variants impact disease predisposition.
|
|
| 9. |
- Chiang, S. C. C., et al.
(författare)
-
Comparison of primary human cytotoxic T-cell and natural killer cell responses reveal similar molecular requirements for lytic granule exocytosis but differences in cytokine production
- 2013
-
Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 121:8, s. 1345-1356
-
Tidskriftsartikel (refereegranskat)abstract
- Cytotoxic lymphocytes, encompassing cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, kill pathogen-infected, neoplastic, or certain hematopoietic cells through the release of perforin-containing lytic granules. In the present study, we first performed probability-state modeling of differentiation and lytic granule markers on CD8(+) T cells to enable the comparison of bona fide CTLs with NK cells. Analysis identified CD57(bright) expression as a reliable phenotype of granule marker-containing CTLs. We then compared CD3(+)CD8(+)CD57(bright) CTLs with NK cells. Healthy adult peripheral blood CD3(+)CD8(+)CD57(bright) CTLs expressed more granzyme B but less perforin than CD3(-)CD56(dim) NK cells. On stimulation, such CTLs degranulated more readily than other T-cell subsets, but had a propensity to degranulate that was similar to NK cells. Remarkably, the CTLs produced cytokines more rapidly and with greater frequency than NK cells. In patients with biallelic mutations in UNC13D, STX11, or STXBP2 associated with familial hemophagocytic lymphohistiocytosis, CTL and NK cell degranulation were similarly impaired. Therefore, cytotoxic lymphocyte subsets have similar requirements for Munc13-4, syntaxin-11, and Munc18-2 in lytic granule exocytosis. The present results provide a detailed comparison of human CD3(+)CD8(+)CD57(bright) CTLs and NK cells and suggest that analysis of CD57(bright) CTL function may prove useful in the diagnosis of primary immunodeficiencies including familial hemophagocytic lymphohistiocytosis.
|
|
| 10. |
- Ingelsson, Erik, et al.
(författare)
-
Detailed Physiologic Characterization Reveals Diverse Mechanisms for Novel Genetic Loci Regulating Glucose and Insulin Metabolism in Humans
- 2010
-
Ingår i: Diabetes. - 0012-1797 .- 1939-327X. ; 59:5, s. 1266-1275
-
Konferensbidrag (refereegranskat)abstract
- OBJECTIVE-Recent genome-wide association studies have revealed loci associated with glucose and insulin-related traits. We aimed to characterize 19 such loci using detailed measures of insulin processing, secretion, and sensitivity to help elucidate their role in regulation of glucose control, insulin secretion and/or action. RESEARCH DESIGN AND METHODS-We investigated associations of loci identified by the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC) with circulating proinsulin, measures of insulin secretion and sensitivity from oral glucose tolerance tests (OGTTs), euglycemic clamps, insulin suppression tests, or frequently sampled intravenous glucose tolerance tests in nondiabetic humans (n = 29,084). RESULTS-The glucose-raising allele in MADD was associated with abnormal insulin processing (a dramatic effect on higher proinsulin levels, but no association with insulinogenic index) at extremely persuasive levels of statistical significance (P = 2.1 x 10(-71)). Defects in insulin processing and insulin secretion were seen in glucose-raising allele carriers at TCF7L2, SCL30A8, GIPR, and C2CD4B. Abnormalities in early insulin secretion were suggested in glucose-raising allele carriers at MTNR1B, GCK, FADS1, DGKB, and PROX1 (lower insulinogenic index; no association with proinsulin or insulin sensitivity). Two loci previously associated with fasting insulin (GCKR and IGF1) were associated with OGTT-derived insulin sensitivity indices in a consistent direction. CONCLUSIONS-Genetic loci identified through their effect on hyperglycemia and/or hyperinsulinemia demonstrate considerable heterogeneity in associations with measures of insulin processing, secretion, and sensitivity. Our findings emphasize the importance of detailed physiological characterization of such loci for improved understanding of pathways associated with alterations in glucose homeostasis and eventually type 2 diabetes. Diabetes 59:1266-1275, 2010
|
|
| 11. |
- Ingelsson, Erik, et al.
(författare)
-
Detailed physiologic characterization reveals diverse mechanisms for novel genetic Loci regulating glucose and insulin metabolism in humans
- 2010
-
Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 59:5, s. 1266-1275
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE Recent genome-wide association studies have revealed loci associated with glucose and insulin-related traits. We aimed to characterize 19 such loci using detailed measures of insulin processing, secretion, and sensitivity to help elucidate their role in regulation of glucose control, insulin secretion and/or action. RESEARCH DESIGN AND METHODS We investigated associations of loci identified by the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC) with circulating proinsulin, measures of insulin secretion and sensitivity from oral glucose tolerance tests (OGTTs), euglycemic clamps, insulin suppression tests, or frequently sampled intravenous glucose tolerance tests in nondiabetic humans (n = 29,084). RESULTS The glucose-raising allele in MADD was associated with abnormal insulin processing (a dramatic effect on higher proinsulin levels, but no association with insulinogenic index) at extremely persuasive levels of statistical significance (P = 2.1 x 10(-71)). Defects in insulin processing and insulin secretion were seen in glucose-raising allele carriers at TCF7L2, SCL30A8, GIPR, and C2CD4B. Abnormalities in early insulin secretion were suggested in glucose-raising allele carriers at MTNR1B, GCK, FADS1, DGKB, and PROX1 (lower insulinogenic index; no association with proinsulin or insulin sensitivity). Two loci previously associated with fasting insulin (GCKR and IGF1) were associated with OGTT-derived insulin sensitivity indices in a consistent direction. CONCLUSIONS Genetic loci identified through their effect on hyperglycemia and/or hyperinsulinemia demonstrate considerable heterogeneity in associations with measures of insulin processing, secretion, and sensitivity. Our findings emphasize the importance of detailed physiological characterization of such loci for improved understanding of pathways associated with alterations in glucose homeostasis and eventually type 2 diabetes.
|
|
| 12. |
- Rodriguez Lorenzo, Andres, et al.
(författare)
-
Anatomy of the motor nerve to the gracilis muscle and its implications in a one-stage microneurovascular gracilis transfer for facial reanimation
- 2010
-
Ingår i: Journal of Plastic, Reconstructive & Aesthetic Surgery. - : Elsevier BV. - 1748-6815 .- 1878-0539. ; 63:1, s. 54-58
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:The present study was conducted to investigate the anatomy of the motor nerve to the gracilis muscle (MNG) to provide the anatomical basis for harvesting a one-stage gracilis transfer with a long nerve for re-animation of the paralysed face.METHODS:An anatomical study was performed on 24 lower-limb specimens (from the pelvis down to the knee) from 12 embalmed cadavers. The MNG was dissected from the surface of the muscle to the obturator foramen. Two anatomical regions were defined in the course of the nerve. The first region includes the part of the nerve that can easily be reached through a standard incision in the medial aspect of the thigh, that is, from the surface of the muscle to the posterior border of the adductor brevis muscle and the second region from there to the obturator foramen. Measurements of both anatomical regions and the maximum length of the nerve were taken with a calliper. The anatomical relations of the nerve were also noted and photo-documented.RESULTS:The median maximum length of the MNG from the surface of gracilis to the posterior border of adductor brevis ('first anatomical region') was 7.7 cm (Range 6.3-10.5 cm); from there to the obturator foramen ('second anatomical region') the length was 3.7 cm (Range 2-6 cm), giving a median length of dissection of the nerve as 11.5 cm (Range 9.9-13.6 cm). Intraneural dissection of the MNG has to be performed proximally in the course of the nerve (the part corresponding to the second anatomical region), just where it runs inside the fascia over the obturator externus muscle.CONCLUSIONS:Over 10-cm length of the MNG can be obtained when dissected along the course of the nerve up to the obturator foramen. To achieve the maximum length, intraneural dissection must normally be performed after the nerve passes the posterior border of the adductor brevis. An endoscopic approach or extended proximal incision is recommended to easily reach the proximal part of the nerve as far as the obturator foramen.
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
|
|
| 16. |
- Holmfeldt, Linda, et al.
(författare)
-
The genomic landscape of hypodiploid acute lymphoblastic leukemia
- 2013
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 45:3, s. 242-252
-
Tidskriftsartikel (refereegranskat)abstract
- The genetic basis of hypodiploid acute lymphoblastic leukemia (ALL), a subtype of ALL characterized by aneuploidy and poor outcome, is unknown. Genomic profiling of 124 hypodiploid ALL cases, including whole-genome and exome sequencing of 40 cases, identified two subtypes that differ in the severity of aneuploidy, transcriptional profiles and submicroscopic genetic alterations. Near-haploid ALL with 24-31 chromosomes harbor alterations targeting receptor tyrosine kinase signaling and Ras signaling (71%) and the lymphoid transcription factor gene IKZF3 (encoding AIOLOS; 13%). In contrast, low-hypodiploid ALL with 32-39 chromosomes are characterized by alterations in TP53 (91.2%) that are commonly present in nontumor cells, IKZF2 (encoding HELIOS; 53%) and RB1 (41%). Both near-haploid and low-hypodiploid leukemic cells show activation of Ras-signaling and phosphoinositide 3-kinase (PI3K)-signaling pathways and are sensitive to PI3K inhibitors, indicating that these drugs should be explored as a new therapeutic strategy for this aggressive form of leukemia.
|
|
| 17. |
|
|
| 18. |
- Hsieh, Yves S. Y., et al.
(författare)
-
Synthesis of the bacteriocin glycopeptide sublancin 168 and S-glycosylated variants
- 2012
-
Ingår i: Organic Letters. - : American Chemical Society (ACS). - 1523-7060 .- 1523-7052. ; 14:7, s. 1910-3
-
Tidskriftsartikel (refereegranskat)abstract
- The synthesis of sublancin 168, a unique S-glucosylated bacteriocin antibiotic, is described. The natural product and two S-glycosylated variants were successfully prepared via native chemical ligation followed by folding. The synthetic glycopeptides were shown to possess primarily an α-helical secondary structure by CD and NMR studies.
|
|
| 19. |
- Hsieh, Yves S. Y., et al.
(författare)
-
Total synthesis of homogeneous variants of hirudin P6 : a post-translationally modified anti-thrombotic leech-derived protein
- 2014
-
Ingår i: Angewandte Chemie International Edition. - : Wiley-VCH Verlagsgesellschaft. - 1433-7851 .- 1521-3773. ; 53:15, s. 3947-51
-
Tidskriftsartikel (refereegranskat)abstract
- Hirudin P6 is a leech-derived anti-thrombotic protein which possesses two post-translational modifications, O-glycosylation and tyrosine sulfation. In this study we report the ligation-based synthesis of a library of hirudin P6 proteins possessing homogeneous glycosylation and sulfation modifications. The nature of the modifications incorporated was shown to have a drastic effect on inhibition against both the fibrinogenolytic and amidolytic activities of thrombin and thus highlights a potential means for attenuating the biological activity of the protein.
|
|
| 20. |
- Huhtaniemi, Ilpo T, et al.
(författare)
-
Effect of Polymorphisms in Selected Genes Involved in Pituitary-Testicular Function on Reproductive Hormones and Phenotype in Aging Men.
- 2010
-
Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 95, s. 1898-1908
-
Tidskriftsartikel (refereegranskat)abstract
- Context: Polymorphisms in genes involved in regulation, biosynthesis, metabolism, and actions of testicular sex hormones may influence hormone balance and phenotype of aging men. Objective: We investigated the relationships between polymorphisms in genes related to pituitary-testicular endocrine function and health status. Design and Setting: Using cross-sectional baseline data, we conducted a multinational prospective cohort observational study consisting of a population survey of community-dwelling men. Participants: A total of 2748 men, aged 40-79 (mean +/- SD, 60.2 + 11.2) yr, were randomly recruited from eight European centers. Forty-three polymorphisms were genotyped in the following genes: androgen receptor (AR), estrogen receptor-alpha and -beta (ESR1 and ESR2), steroid 5alpha-reductase type II (SRD5A2), 17alpha-hydroxylase/17,20-lyase (CYP17A1), aromatase (CYP19A1), sex hormone-binding globulin (SHBG), LH beta-subunit (LHB), and LH receptor (LHCGR). Main Outcome Measures: We measured the associations between gene polymorphisms and endocrine, metabolic, and phenotypic parameters related to aging and sex hormone action. Results: Several polymorphisms in SHBG, ESR2, AR, CYP19A1, and LHB were significantly associated with circulating levels of SHBG, LH, total, free, and bioavailable testosterone and estradiol, the LH x testosterone product, and indices of insulin sensitivity. Apart from several previously reported associations between genes affecting estrogen levels and heel ultrasound parameters, no associations existed between polymorphisms and nonhormonal variables (anthropometry, blood lipids, blood pressure, hemoglobin, prostate symptoms, prostate-specific antigen, sexual dysfunction, cognition). Conclusion: In aging men, polymorphisms in genes related to the pituitary-testicular endocrine function significantly influence circulating LH, testosterone, and estradiol levels, but the downstream effects may be too small to influence secondary phenotypic parameters.
|
|
| 21. |
- Lee, David M., et al.
(författare)
-
Endogenous hormones, androgen receptor CAG repeat length and fluid cognition in middle-aged and older men: results from the European Male Ageing Study
- 2010
-
Ingår i: European Journal of Endocrinology. - 1479-683X. ; 162:6, s. 1155-1164
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Data remain divergent regarding the activational effects of endogenous hormones on adult cognitive function. We examined the association between cognition, hormones and androgen receptor (AR) CAG repeat length in a large cohort of men. Design: Community-based, cross-sectional study of 3369 men aged 40-79 years. Methods: Cognition tests were the Rey-Osterrieth Complex Figure, Camden Topographical Recognition Memory and Digit-Symbol Substitution. A fluid cognition (FC) z-score was computed from the individual tests. Testosterone, oestradiol (OE2) and 5 alpha-dihydrotestosterone were measured by gas chromatography-mass spectrometry; DHEAS, LH, FSH and sex hormone-binding globulin (SHBG) by electrochemiluminescence. Free testosterone and OE2 were calculated from total hormone, SHBG and albumin. CAG repeat lengths were assayed by PCR genotyping. Results: Total testosterone and free testosterone were associated with higher FC z-scores, LH and FSH with lower FC z-scores in age-adjusted linear regressions. After adjusting for health, lifestyle and centre, a modest association was only observed between DHEAS and a lower FC z-score (beta=-0.011, P=0.02), although this was driven by subjects with DHEAS levels > 10 mu mol/l. Locally weighted plots revealed no threshold effects between hormones and FC. There was no association between CAG repeat length and FC z-score after adjustment for age and centre (beta=-0.007, P=0.06), nor any interaction effect between CAG repeat length and hormones. Conclusion: Our results suggest that endogenous hormones are not associated with a vision-based measure of FC among healthy, community-dwelling men. Further studies are warranted to determine whether 'high' DHEAS levels are associated with poorer performance on a broader range of neuropsychological tests.
|
|
| 22. |
|
|
| 23. |
- Payne, T. E., et al.
(författare)
-
Guidelines for thermodynamic sorption modelling in the context of radioactive waste disposal
- 2013
-
Ingår i: Environmental Modelling and Software. - : Elsevier BV. - 1364-8152. ; 42, s. 143-156
-
Tidskriftsartikel (refereegranskat)abstract
- Thermodynamic sorption models (TSMs) offer the potential to improve the incorporation of sorption in environmental modelling of contaminant migration. One specific application is safety cases for radioactive waste repositories, in which radionuclide sorption on mineral surfaces is usually described using distribution coefficients (K-d values). TSMs can be utilised to provide a scientific basis for the range of K-d values included in the repository safety case, and for assessing the response of K-d to changes in chemical conditions. The development of a TSM involves a series of decisions on model features such as numbers and types of surface sites, sorption reactions and electrostatic correction factors. There has been a lack of consensus on the best ways to develop such models, and on the methods of determination of associated parameter values. The present paper therefore presents recommendations on a number of aspects of model development, which are applicable both to radioactive waste disposal and broader environmental applications.The TSM should be calibrated using a comprehensive sorption data set for the contaminant of interest, showing the impact of major geochemical parameters including pH, ionic strength, contaminant concentration, the effect of ligands, and major competing ions. Complex natural materials should be thoroughly characterised in terms of mineralogy, surface area, cation exchange capacity, and presence of impurities. During the application of numerical optimisation programs to simulate sorption data, it is often preferable that the TSM should be fitted to the experimentally determined K-d parameter, rather than to the frequently used percentage sorbed. Two different modelling approaches, the component additivity and generalised composite, can be used for modelling sorption data for complex materials such as soils. Both approaches may be coupled to the same critically reviewed aqueous thermodynamic data sets, and may incorporate the same, or similar, surface reactions and surface species. The quality of the final sorption model can be assessed against the following characteristics: an appropriate level of complexity, documented and traceable decisions, internal consistency, limitations on the number of adjustable parameter values, an adequate fit to a comprehensive calibration data set, and capability of simulating independent data sets. Key recommendations for the process of TSM development include: definition of modelling objectives, identification of major decision points, a clear decision-making rationale with reference to experimental or theoretical evidence, utilisation of a suitable consultative and iterative model development process, testing to the maximum practicable extent, and thorough documentation of key decisions. These recommendations are consistent with international benchmarks for environmental modelling.
|
|
| 24. |
|
|
| 25. |
- Thomas, Gemma L., et al.
(författare)
-
Peptide ligations accelerated by N-terminal aspartate and glutamate residues.
- 2011
-
Ingår i: Organic Letters. - : American Chemical Society (ACS). - 1523-7060 .- 1523-7052. ; 13:18, s. 4770-3
-
Tidskriftsartikel (refereegranskat)abstract
- A novel application of intramolecular base catalysis confers enhanced reaction rates for aminolysis ligations between peptide thioesters and peptides bearing N-terminal aspartate or glutamate residues. The broad scope of this process and its application in the total synthesis of the diabetes drug exenatide is demonstrated.
|
|
