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- Lønborg, C., et al.
(författare)
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A global database of dissolved organic matter (DOM) concentration measurements in coastal waters (CoastDOM v1)
- 2024
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Ingår i: Earth System Science Data. - : Copernicus Publications. - 1866-3508 .- 1866-3516. ; 16:2, s. 1107-1119
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP) concentrations are used to characterize the dissolved organic matter (DOM) pool and are important components ofbiogeochemical cycling in the coastal ocean. Here, we present the first edition of a global database (CoastDOMv1; available at https://doi.org/10.1594/PANGAEA.964012, Lønborg et al., 2023) compiling previously published and unpublished measurements of DOC, DON, and DOP in coastal waters. These data are complementedby hydrographic data such as temperature and salinity and, to the extent possible, other biogeochemical variables(e.g. chlorophyll a, inorganic nutrients) and the inorganic carbon system (e.g. dissolved inorganic carbon andtotal alkalinity). Overall, CoastDOM v1 includes observations of concentrations from all continents. However,most data were collected in the Northern Hemisphere, with a clear gap in DOM measurements from the SouthernHemisphere. The data included were collected from 1978 to 2022 and consist of 62 338 data points for DOC,20 356 for DON, and 13 533 for DOP. The number of measurements decreases progressively in the sequenceDOC > DON > DOP, reflecting both differences in the maturity of the analytical methods and the greater focuson carbon cycling by the aquatic science community. The global database shows that the average DOC concentration in coastal waters (average ± standard deviation (SD): 182±314 µmolC L−1; median: 103 µmolC L−1) is13-fold higher than the average coastal DON concentration (13.6 ± 30.4 µmol N L−1; median: 8.0 µmol N L−1),which is itself 39-fold higher than the average coastal DOP concentration (0.34 ± 1.11 µmol P L−1; median:0.18 µmol P L−1). This dataset will be useful for identifying global spatial and temporal patterns in DOM and willhelp facilitate the reuse of DOC, DON, and DOP data in studies aimed at better characterizing local biogeochemical processes; closing nutrient budgets; estimating carbon, nitrogen, and phosphorous pools; and establishing abaseline for modelling future changes in coastal waters.
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| 2. |
- Chakroborty, Anand, et al.
(författare)
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Modified Hederagenin Derivatives Demonstrate Ex Vivo Anthelmintic Activity against Fasciola hepatica
- 2023
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Ingår i: Pharmaceutics. - : MDPI AG. - 1999-4923. ; 15:7
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Tidskriftsartikel (refereegranskat)abstract
- Infection with Fasciola hepatica (liver fluke) causes fasciolosis (or fascioliasis) and poses a considerable economic as well as welfare burden to both the agricultural and animal health sectors. Here, we explore the ex vivo anthelmintic potential of synthetic derivatives of hederagenin, isolated in bulk from Hedera helix. Thirty-six compounds were initially screened against F. hepatica newly excysted juveniles (NEJs) of the Italian strain. Eleven of these compounds were active against NEJs and were selected for further study, using adult F. hepatica derived from a local abattoir (provenance unknown). From these eleven compounds, six demonstrated activity and were further assessed against immature liver flukes of the Italian strain. Subsequently, the most active compounds (n = 5) were further evaluated in ex vivo dose response experiments against adult Italian strain liver flukes. Overall, MC042 was identified as the most active molecule and the EC50 obtained from immature and adult liver fluke assays (at 24 h post co-culture) are estimated as 1.07 & mu;M and 13.02 & mu;M, respectively. When compared to the in vitro cytotoxicity of MDBK bovine cell line, MC042 demonstrated the highest anthelmintic selectivity (44.37 for immature and 3.64 for adult flukes). These data indicate that modified hederagenins display properties suitable for further investigations as candidate flukicides.
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| 4. |
- Anderson, Orlagh, et al.
(författare)
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An investigation of the antileishmanial properties of semi-synthetic saponins
- 2020
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Ingår i: RSC MEDICINAL CHEMISTRY. - : Royal Society of Chemistry (RSC). - 2632-8682. ; 11:7, s. 833-842
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Tidskriftsartikel (refereegranskat)abstract
- Leishmaniasis is a neglected tropical disease caused by insect-vector borne protozoan parasites of the,Leishmania species. Whilst infection threatens and affects millions of the global poor, vaccines are absent and drug therapy limited. Extensive efforts have recently been made to discover new leads from small molecule synthetic compound libraries held by industry; however, the number of new chemical entities identified and entering development as anti-leishmanials has been very low. This has led to increased interest in the possibility of discovering naturally derived compounds with potent antileishmanial activity which may be developed towards clinical applications. Plant-derived triterpenoid and steroidal saponins have long been considered as anti-microbials and here we describe an investigation of a library of 137 natural (9) and semi-synthetic saponins (128) for activity againstLeishmania mexicana, a causative agent of cutaneous leishmaniasis. The triterpenoid sapogenin, hederagenin, readily obtained in large quantities fromHedera helix(common ivy), was converted into a range of 128 derivatives. These semi-synthetic compounds, as well as saponins isolated from ivy, were examined with a phenotypic screening approach to identify potent and selective anti-leishmanial hits. This led to the identification of 12 compounds, including the natural saponin gypsogenin, demonstrating high potency (ED50< 10.5 mu M) against axenicL. mexicanaamastigotes, the mammalian pathogenic form. One of these, hederagenin disuccinate, was sufficiently non-toxic to the macrophage host cell to facilitate further analyses, selectivity index (SI) > 10. Whilst this was not active in an infected cell model, the anti-leishmanial properties of hederagenin-derivatives have been demonstrated, and the possibility of improving the selectivity of natural hederagenin through chemical modification has been established.
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| 7. |
- Chakroborty, Anand, et al.
(författare)
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Flukicidal effects of abietane diterpenoid derived analogues against the food borne pathogen Fasciola hepatica
- 2022
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Ingår i: Veterinary parasitology. - : Elsevier BV. - 0304-4017 .- 1873-2550. ; 309, s. 109766-
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Tidskriftsartikel (refereegranskat)abstract
- Control of liver fluke infections remains a significant challenge in the livestock sector due to widespread distribution of drug resistant parasite populations. In particular, increasing prevalence and economic losses due to infection with Fasciola hepatica is a direct result of drug resistance to the gold standard flukicide, triclabendazole. Sustainable control of this significant zoonotic pathogen, therefore, urgently requires the identification of new anthelmintics. Plants represent a source of molecules with potential flukicidal effects and, amongst their secondary metabolites, the diterpenoid abietic acids can be isolated in large quantities. In this study, nineteen (19) chemically modified abietic acid analogues (MC_X) were first evaluated for their anthelmintic activities against F. hepatica newly excysted juveniles (NEJs, from the laboratory-derived Italian strain); from this, 6 analogues were secondly evaluated for their anthelmintic activities against adult wild strain flukes. One analogue, MC010, was progressed further against 8-week immature- and 12-week mature Italian strain flukes. Here, MC010 demonstrated moderate activity against both of these intra-mammalian fluke stages (with an adult fluke EC50 = 12.97 mu M at 72 h post culture). Overt mammalian cell toxicity of MC010 was inferred from the Madin-Darby bovine kidney (MDBK) cell line (CC50 = 17.52 mu M at 24 h post culture) and demonstrated that medicinal chemistry improvements are necessary before abietic acid analogues could be considered as potential anthelmintics against liver fluke pathogens
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| 9. |
- Lee, David M., et al.
(författare)
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Association between 25-hydroxyvitamin D levels and cognitive performance in middle-aged and older European men
- 2009
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Ingår i: Journal of Neurology, Neurosurgery and Psychiatry. - : BMJ. - 1468-330X .- 0022-3050. ; 80:7, s. 722-729
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Tidskriftsartikel (refereegranskat)abstract
- Background: Although there is evidence that vitamin D inadequacy may be linked to adverse cognitive outcomes, results from studies on this topic have been inconsistent. The aim of this trial was to examine the association between 25-hydroxyvitamin D (25(OH) D) levels and cognitive performance in middle-aged and older European men. Methods: This population-based cross-sectional study included 3,369 men aged 40-79 years from eight centres enrolled in the European Male Ageing Study. Cognitive function was assessed using the Rey-Osterrieth Complex Figure (ROCF) test, the Camden Topographical Recognition Memory (CTRM) test and the Digit Symbol Substitution Test (DSST). Serum 25(OH) D levels were measured by radioimmunoassay. Additional assessments included measurement of physical activity, functional performance and mood/depression. Associations between cognitive function and 25(OH) D levels were explored using locally weighted and linear regression models. Results: In total, 3,133 men (mean (+/- SD) age 60 +/- 11 years) were included in the analysis. The mean (+/- SD) 25(OH) D concentration was 63 +/- 31 nmol/l. In age-adjusted linear regressions, high levels of 25(OH) D were associated with high scores on the copy component of the ROCF test (beta per 10 nmol/l = 0.096; 95% CI 0.049 to 0.144), the CTRM test (beta per 10 nmol/l= 0.075; 95% CI 0.026 to 0.124) and the DSST (beta per 10 nmol/l = 0.318; 95% CI 0.235 to 0.401). After adjusting for additional confounders, 25(OH) D levels were associated with only score on the DSST (beta per 10 nmol/l = 0.152; 95% CI 0.051 to 0.253). Locally weighted and spline regressions suggested the relationship between 25(OH) D concentration and cognitive function was most pronounced at 25(OH) D concentrations below 35 nmol/l. Conclusion: In this study, lower 25(OH) D levels were associated with poorer performance on the DSST. Further research is warranted to determine whether vitamin D sufficiency might have a role in preserving cognitive function in older adults.
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| 10. |
- Lee, David M., et al.
(författare)
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Association of hypogonadism with vitamin D status: the European Male Ageing Study
- 2012
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Ingår i: European Journal of Endocrinology. - 1479-683X. ; 166:1, s. 77-85
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Interrelationships between hormones of the hypothalamic-pituitary-testicular (HPT) axis, hypogonadism, vitamin D and seasonality remain poorly defined. We investigated whether HPT axis hormones and hypogonadism are associated with serum levels of 25-hydroxyvitamin D (25(OH)D) in men. Design and methods: Cross-sectional survey of 3369 community-dwelling men aged 40-79 years in eight European centres. Testosterone (T), oestradiol (E(2)) and dihydrotestosterone were measured by gas chromatography-mass spectrometry; LH, FSH, sex hormone binding globulin (SHBG), 25(OH)D and parathyroid hormone by immunoassay. Free T was calculated from total T, SHBG and albumin. Gonadal status was categorised as eugonadal (normal T/LH), secondary (low T, low/normal LH), primary (low T, elevated LH) and compensated (normal T, elevated LH) hypogonadism. Associations of HPT axis hormones with 25(OH)D were examined using linear regression and hypogonadism with vitamin D using multinomial logistic regression. Results: In univariate analyses, free T levels were lower (P=0.02) and E(2) and LH levels were higher (P<0.05) in men with vitamin D deficiency (25(OH)D <50 nmol/l). 25(OH)D was positively associated with total and free T and negatively with E(2) and LH in age- and centre-adjusted linear regressions. After adjusting for health and lifestyle factors, no significant associations were observed between 25(OH)D and individual hormones of the HPT axis. However, vitamin D deficiency was significantly associated with compensated (relative risk ratio (RRR)=1.52, P=0.03) and secondary hypogonadism (RRR=1.16, P=0.05). Seasonal variation was only observed for 25(OH)D (P<0.001). Conclusions: Secondary and compensated hypogonadism were associated with vitamin D deficiency and the clinical significance of this relationship warrants further investigation.
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