| 1. |
- Alvarez, Maria Teresa, et al.
(författare)
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Lab-scale production of biogenic sulphide for metal precipitation in remote areas
- 2012
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Ingår i: International Journal of Environment and Waste Management. - 1478-9876. ; 9:3-4, s. 313-329
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Tidskriftsartikel (refereegranskat)abstract
- Batch cultures with wheat straw, biomass of Paja Brava (Festuca orthophylla), filter paper, newspaper and beech leaves (Fagus sylvatica) were established to produce sulphide. Sulphide production, sulphate reduction, concentration of Volatile Fatty Acids (VFAs), enzyme activities and Fluorescence in situ hybridisation were determined. Approximately 5 mM of sulphide was produced during anaerobic digestion of wheat straw, while the production with newspaper as carbon source was the lowest (ca.1 mM). The sulphide production (2-5 mM) in the semi-continuous culture of the consortium A10, using wheat straw supported Cu(II), Pb (II) and Zn (II) removal up to 90%.
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| 2. |
- Arévalo-Lopéz, Diandra, et al.
(författare)
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Leishmanicidal and cytotoxic activity from plants used in Tacana traditional medicine (Bolivia)
- 2018
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Ingår i: Journal of Ethnopharmacology. - : Elsevier BV. - 0378-8741. ; 216, s. 120-133
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Tidskriftsartikel (refereegranskat)abstract
- Etnopharmacological relevance: Thirty-eight Tacana medicinal plant species used to treat skin problems, including leishmania ulcers, skin infections, inflammation and wound healing, were collected in the community of Buena Vista, Bolivia, with the Tacana people. Twenty two species are documented for the first time as medicinal plants for this ethnic group living in the northern area of the Department of La Paz. Aim of the study: To evaluate the leishmanicidal effect (IC50) and cytotoxicity (LD50) of the selected plants. To carry out bioguided studies on the active extracts. To assess the potential of Bolivian plant biodiversity associated with traditional knowledge in the discovery of alternative sources to fight leishmaniasis. Materials and methods: Seventy three ethanol extracts were prepared from 38 species by maceration and were evaluated in vitro against promastigotes of Leishmania amazonensis and L. braziliensis. Active extracts (IC50 ≤ 50 μg/mL) were fractionated by chromatography on Silica gel column and the fractions were assessed against the two Leishmania strains. The most active fractions and the crude extracts were evaluated against reference strains of L. amazonensis, L. braziliensis, L. aethiopica, two native strains (L. Lainsoni and L. braziliensis) and for cytotoxicity against HeLa cells. The chromatographic profile of the active fractions was obtained by reverse phase chromatography using HPLC. Results: From the 73 extracts, 39 extracts (53.4%) were inactive and 34 showed activity. Thirteen species were sselected for bioguided studies. The crude extracts and their 36 fractions were evaluated against two Leishmania strains. The most active fraction were tested in a panel of five leishmania strains and for cytotoxicity. The Selective Index (SI = LD50/IC50) was calculated, and were generally low. Retention time and UV spectra were recorded for the active fractions by HPLC-DAD using a reverse phase column. Profiles were very different from each other, showing the presence of different compounds. Conclusion: Bolivian traditional knowledge from the Tacanba was useful to identify plants with effect on Leishmania promastigotes. Chromatographic bioguided studies showed stronger leishmanicidal and cytotoxic activity for the medium polar fraction. HPLC analysis showed different chromatographic profiles of the active fractions.
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| 3. |
- Braga, Antonio, et al.
(författare)
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Panchromatic sensitized solar cells based on metal sulfide quantum dots grown directly on nanostructured TiO2 electrodes
- 2011
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 2:5, s. 454-460
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Tidskriftsartikel (refereegranskat)abstract
- The use of narrow band gap semiconductors such as PbS may expand the light absorption range to the near-infrared region in quantum-dot-sensitized solar cells (QDSCs), increasing the generated photocurrent. However, the application of PbS as a sensitizer in QDSCs causes some problems of stability and high recombination. Here, we show that the direct growth of a CdS coating layer on previously deposited PbS by the simple method of successive ionic layer adsorption and reaction (SILAR) minimizes these problems. A remarkable short-circuit current density for PbS/CdS QDSCs is demonstrated, ∼11 mA/cm2, compared to that of PbS QDSCs, with photocurrents lower than 4 mA/cm2, using polysulfide electrolyte in both cells. The cell efficiency reached a promising 2.21% under 1 sun of simulated irradiation (AM1.5G, 100 mW/cm2). Enhancement of the solar cell performance beyond the arithmetic addition of the efficiencies of the single constituents (PbS and CdS) is demonstrated for the nanocomposite PbS/CdS configuration. PbS dramatically increases the obtained photocurrents, and the CdS coating stabilizes the solar cell behavior. © 2011 American Chemical Society.
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| 4. |
- Calla-Magariños, Jacqueline, 1963-, et al.
(författare)
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Quinolinic alkaloids from Galipea longiflora suppress inflammatory cytokine production in vitro and control inflammatory reaction in vivo upon Leishmania infection
-
Ingår i: Scandinavian Journal of Immunology. - 0300-9475 .- 1365-3083.
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Tidskriftsartikel (refereegranskat)abstract
- An antileishmanial activity of quinolinic alkaloids from Galipea longiflora Krause, known as Evanta, has been demonstrated. We have previously shown that, apart from its leishmanicidal effect, in vitro pretreatment of spleen cells with an alkaloid extract of Evanta (AEE) interfered with the proliferation and interferon-g production in lymphocytes polyclonally activated either with concanavalin A or anti-CD3. In the present study, we investigated if AEE could interfere with antigen-specific lymphocyte activation. We found that in vitro and in vivo treatment reduced recall lymphocyte responses, as measured by IFN-g production (55 % and 63 % reduction compared to untreated cells, respectively). Apart from IFN-g, the production of IL-12 and TNF were also suppressed. No effects were observed for meglumine antimoniate (SbV), the conventional drug used to treat leishmaniasis. When mice infected with Leishmania braziliensis promastigotes in the hind footpad were treated with AEE, the dynamics of the infection changed and the footpath thickness was efficiently controlled. The parasite load was also reduced but to a lesser extent than upon treatment with SbV. Combined treatment efficiently controlled both the thickness and parasite load since smaller lesions during the entire course of the infection were seen in the mice treated with AEE plus SbV compared with AEE or SbV alone. We discuss the benefits of combined administration of AEE plus SbV.
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| 5. |
- Castañeta, Grover, et al.
(författare)
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Microwave-Assisted Semisynthesis and Leishmanicidal Activity of Some Phenolic Constituents from Lichens
- 2023
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Ingår i: separations. - 2297-8739. ; 10:10
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Tidskriftsartikel (refereegranskat)abstract
- Leishmaniasis is considered one of the most untreated tropical diseases in the world. In this study, we investigated the in vitro leishmanicidal activity and cytotoxicity of various isolated lichen substances, including atranorin (1), usnic acid (2), gyrophoric acid (3), salazinic acid (4), galbinic acid (5), and parietin (6), and some semi-synthetic imine derivatives of usnic acid (7, 8, 9) and atranorin (10, 11, 12, 13). Imine condensation reactions with hydrazine and several amines were assisted by microwave heating, an efficient and eco-friendly energy source. The most interesting result was obtained for compound 2, which has high leishmanicidal activity but also high cytotoxicity. This cytotoxicity was mitigated in its derivative, 9, with better selectivity and high antileishmanic activity. This result may indicate that the usnic acid derivative (9) obtained using condensation with two cyclohexylamine groups is a promising lead compound for the discovery of new semisynthetic antiparasitic drugs.
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| 6. |
- Cirera, Borja, et al.
(författare)
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Thermal selectivity of intermolecular versus intramolecular reactions on surfaces
- 2016
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 7:11002
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Tidskriftsartikel (refereegranskat)abstract
- On-surface synthesis is a promising strategy for engineering heteroatomic covalent nanoarchitectures with prospects in electronics, optoelectronics and photovoltaics. Here we report the thermal tunability of reaction pathways of a molecular precursor in order to select intramolecular versus intermolecular reactions, yielding monomeric or polymeric phthalocyanine derivatives, respectively. Deposition of tetra-aza-porphyrin species bearing ethyl termini on Au(111) held at room temperature results in a close-packed assembly. Upon annealing from room temperature to 275 °C, the molecular precursors undergo a series of covalent reactions via their ethyl termini, giving rise to phthalocyanine tapes. However, deposition of the tetra-aza-porphyrin derivatives on Au(111) held at 300 °C results in the formation and self-assembly of monomeric phthalocyanines. A systematic scanning tunnelling microscopy study of reaction intermediates, combined with density functional calculations, suggests a [2+2] cycloaddition as responsible for the initial linkage between molecular precursors, whereas the monomeric reaction is rationalized as an electrocyclic ring closure.
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| 7. |
- Conde Mellado, Alberto, et al.
(författare)
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A lateral active suspension for conventional railway bogies
- 2009
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Ingår i: Vehicle System Dynamics. - : Taylor & Francis. - 0042-3114 .- 1744-5159. ; 47:1, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- The present paper describes an active centring system for railway vehicles. The proposed solution is based on lateral pneumatic actuators placed between bogie and car body connected to the vertical secondary suspension air springs. The objective of the developed centring system is twofold: the improvement of the curving behaviour of the train and the decrease of the lateral acceleration perceived by the passenger in curve negotiation thanks to the reduction of the ‘souplesse’ coefficient. The system is described in detail in the paper. Results from simulations are included considering a bidimensional model of the vehicle, and a detailed model of the air spring and control valves. The performance in curve negotiation of a vehicle equipped with this system and a conventional one is compared. Specifically, lateral displacements of the secondary suspension, roll angle and lateral accelerations are analysed. The results show noticeable performance improvements in the vehicle curving behaviour. The proposed centring system can be implemented in a conventional bogie without special design requirements; and due to the low air consumption, additional pressurised reservoirs are not required.
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| 8. |
- Erosa-Rejon, Gilda J., et al.
(författare)
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Benzochromenes from the roots of Bourreria pulchra
- 2010
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Ingår i: Phytochemistry Letters. - : Elsevier BV. - 1874-3900. ; 3:1, s. 9-12
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Tidskriftsartikel (refereegranskat)abstract
- Two new benzochromenes, (6,6-dimethyl-2-methoxy-6H-benzo[c]chromen-9-yl)methanol (1), and 2-methoxy-6,6-dimethyl-6H-benzo[c]chromen-9-carbaldehyde (2), together with several already known metabolites, were isolated from the root extract of Bourreria pulchra (Boraginaceae). The structures of 1 and 2 were established on the basis of their spectroscopic data. Both were assayed for in vitro antiprotozoan activity, and especially 1 was found to possess significant activity against Leishmania mexicana and Trypanosoma cruzi parasites (IC50 4.6 mu g/mL and 7.5 mu g/mL, respectively). (C) 2009 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
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| 9. |
- Escobar, Zilma, et al.
(författare)
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Synthesis of poinsettifolin A
- 2014
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 70:47, s. 9052-9056
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Tidskriftsartikel (refereegranskat)abstract
- A synthesis of poinsettifolin A (1), a prenylated flavonol isolated from Dorstenia poinsettifolia, is described. Two routes starting from quercetin were explored, and 1 could be prepared if a prenyl group first was incorporated at C-6 of the protected quercetin followed by a condensation with citral at C-8. The key synthetic steps are a Mitsunobu reaction, an europium (III)-catalysed Claisen rearrangement coupled with cross-metathesis, and a benzopyran-forming geranylation. The two geranylated 3,5,3',4'-tetrahydroxyflavonols prepared, 1 and 3, were assayed for antileishmanial activity against Leishmania amazonensis and Leishmania braziliensis, and found to be active. Compound 3 showed cytotoxic activity against leukaemia and lung cancer cells while 1 lacked cytotoxicity. (C) 2014 Elsevier Ltd. All rights reserved.
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| 10. |
- Gimenez-Gomez, Alberto, et al.
(författare)
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Cover Feature: Unveiling the Potential of Heterogeneous Catalysts for Molecular Solar Thermal Systems (Chem. Eur. J. 1/2024)
- 2024
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Ingår i: Chemistry - A European Journal. - 1521-3765 .- 0947-6539. ; 30:1
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Trapping sunlight energy into chemical bonds has become an important method for storing renewable energy and releasing it on demand. To illustrate the new catalyst-testing protocol, a cyclic road shows the photoisomerization process trapping sunlight (top) and the back-conversion catalytic reaction releasing heat. The bottom wheel indicates that up to 27 different catalysts were studied. More information can be found in the Research Article by I. Funes-Ardoiz, D. Sampedro and co-workers (DOI: 10.1002/chem.202303230).
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| 11. |
- Gimenez-Gomez, Alberto, et al.
(författare)
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Unveiling the Potential of Heterogeneous Catalysts for Molecular Solar Thermal Systems
- 2024
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Ingår i: Chemistry - A European Journal. - 1521-3765 .- 0947-6539. ; 30:1
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Tidskriftsartikel (refereegranskat)abstract
- Solar energy utilization has gained considerable attention due to its abundance and renewability. However, its intermittent nature presents a challenge in harnessing its full potential. The development of energy storing compounds capable of capturing and releasing solar energy on demand has emerged as a potential solution. These compounds undergo a photochemical transformation that results in a high-energy metastable photoisomer, which stores solar energy in the form of chemical bonds and can release it as heat when required. Such systems are referred to as MOlecular Solar Thermal (MOST)-systems. Although the photoisomerization of MOST systems has been vastly studied, its back-conversion, particularly using heterogeneous catalysts, is still underexplored and the development of effective catalysts for releasing stored energy is crucial. Herein we compare the performance of 27 heterogeneous catalysts releasing the stored energy in an efficient Norbornadiene/Quadricyclane (NBD/QC) MOST system. We report the first benchmarking of heterogeneous catalysts for a MOST system using a robust comparison method of the catalysts’ activity and monitoring the conversion using UV-Visible (UV-Vis) spectroscopy. Our findings provide insights into the development of effective catalysts for MOST systems. We anticipate that our assay will reveal the necessity of further investigation on heterogeneous catalysis.
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| 12. |
- Gonzales-Ramirez, Mariela, et al.
(författare)
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Trichilones A–E: New Limonoids from Trichilia adolfi
- 2021
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Ingår i: Molecules. - : MDPI AG. - 1420-3049. ; 26:11
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Tidskriftsartikel (refereegranskat)abstract
- In addition to the trichilianones A–D recently reported from Trichilia adolfi, a continuing investigation of the chemical constituents of the ethanol extract of the bark of this medicinal plant yielded the five new limonoids 1–5. They are characterized by having four fused rings and are new examples of prieurianin-type limonoids, having a ε-lactone which in 4 and 5 is α, β- unsaturated. The structures of the isolated metabolites were determined by high field NMR spectroscopy and HR mass spectrometry. The new metabolites were shown to have the ε-lactone fused with a tetrahydrofuran ring which is connected to an oxidized hexane ring joined with a cyclo-pentanone having a 3-furanyl substituent. As the crude extract possesses antileishmanial activity, the compounds were assayed for cytotoxic and antiparasitic activities in vitro in murine macrophage cells (raw 264.7 cells) and in Leishmania amazoniensis as well as L. braziliensis promastigotes. Metabolites 1–3 and 5 showed moderate cytotoxicity (between 30–94 μg/mL) but are not responsible for the antileishmanial effect of the extract.
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| 13. |
- Limachi, Ivan, et al.
(författare)
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Antiparasitic metabolites from hyptis brevipes, a tacana medicinal plant
- 2019
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Ingår i: Natural Product Communications. - 1934-578X. ; 14:1, s. 55-58
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Tidskriftsartikel (refereegranskat)abstract
- A bioassay screening against protozoa parasites of several Tacana medicinal plants gave Hyptis brevipes (Id'ene eidhue), traditionally used as decoction for intestinal parasites, as the most active extract. In this work we did a bioguided isolation of active constituents found in leaves. Structure elucidation was carried out by NMR spectroscopy and MS spectrometry analyses. Active constituents showed differentiated activity towards Giardia lamblia, Trypanosoma cruzi, several Leishmania strains, Plasmodium falciparum and cytotoxicity against HeLa cells. Brevipolide H (1) was the less cytotoxic and best antiparasitic, while the catechol derivative (2) the most active and cytotoxic.
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| 14. |
- Limachi, Ivan, et al.
(författare)
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Trichilianones A-D, Novel Cyclopropane-Type Limonoids from Trichilia adolfi
- 2021
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Ingår i: Molecules (Basel, Switzerland). - : MDPI AG. - 1420-3049. ; 26:4
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Tidskriftsartikel (refereegranskat)abstract
- The fractionation of an ethanol extract of the bark of Trichilia adolfi yielded four novel limonoids (trichilinones A-D, 1-4), with five fused rings and related to the hortiolide-type limonoids. Starting with an ε-lactone, which is α,β-unsaturated in trichilinones A and D (1 and 4), attached to a tetrahydrofuran ring that is connected to an unusual bicyclo [5.1.0] hexane system, joined with a cyclopentanone with a 3-furanyl substituent [(2-oxo)-furan-(5H)-3-yl in trichilinone D (4)], the four compounds isolated display a new 7/5/3/5/5 limonoid ring system. Their structures were established based on extensive analysis of NMR spectroscopic data. As the crude extract possessed anti-leishmanial properties, the compounds were assayed for cytotoxic and anti-parasitic activities in vitro in murine macrophages cells (Raw 264.7) and leishmania promastigotes (L. amazoniensis and L. braziliensis), respectively. The compounds showed moderate cytotoxicity (approximately 70 μg/mL), but are not responsible for the leishmanicidal effect of the extract.
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| 15. |
- Maldonado, Eliana, et al.
(författare)
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Antileishmanial metabolites from Trixis antimenorrhoea
- 2014
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Ingår i: Phytochemistry Letters. - : Elsevier BV. - 1874-3900. ; 10, s. 281-286
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Tidskriftsartikel (refereegranskat)abstract
- An ethanol extract of the aerial parts of Trixis antimenorrhoea was found to possess activity toward Leishmania brasiliensis. Two new metabolites, the nortrixane 1 and the trixanolide 2, and eleven known were isolated and characterized. The antileishmanial activity against the promastigote form of L. amazonensis and L. brasiliensis was assayed in vitro, and 2 exhibited potent activity with IC50 values below 1 mu g/mL toward both strains. The structures of the isolated compounds were elucidated by NMR spectroscopy and high-resolution mass spectrometry, and the absolute configuration of 2 was determined by using Mosher's ester protocol. (C) 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
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| 16. |
- Maldonado, Eliana M., et al.
(författare)
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Antileishmanial metabolites from Lantana balansae
- 2016
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Ingår i: Brazilian Journal of Pharmacognosy. - : Springer Science and Business Media LLC. - 0102-695X. ; 26:2, s. 180-183
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Tidskriftsartikel (refereegranskat)abstract
- Eleven compounds, 12-oxo-phytodienoic acid (1), persicogenin (2), eriodictyol 3ʹ4ʹ,7-trimethyl ether (3), phytol (4), spathulenol (5), 4-hydroxycinnamic acid (6), onopordin (7), 5,8,4ʹ-trihydroxy-7,3ʹ-dimethoxyflavone (8), quercetin (9), jaceosidin (10), and 8-hydroxyluteolin (11), were isolated from an ethanol extract of Lantana balansae Briq., Verbenaceae, that was found to possess antileishmanial activ-ity. The structures of the compounds were determined by NMR spectroscopy and HR mass spectrometry, and 1, 2, 3, 7, 8 and 9 were investigated for antiprotozoal activity toward promastigotes of Leishmania amazonensis and Leishmania braziliensis. Compound 1 was shown to be the most potent, with the IC50 values 2.0µM toward L. amazonensis and 0.68µM toward L. braziliensis, although less potent than the positive control Amphotericin B. All compounds have been reported previously, but this is the first report of the isolation of a cyclopentenone fatty acid (1) and flavanones (2 and 3) from a Lantana species.
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| 17. |
- Mendoza, Laura, et al.
(författare)
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Laccase mediator system for activation of agarose gel: Application for immobilization of proteins
- 2011
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Ingår i: Journal of Molecular Catalysis B: Enzymatic. - : Elsevier BV. - 1873-3158 .- 1381-1177. ; 68:3-4, s. 270-274
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Tidskriftsartikel (refereegranskat)abstract
- Cross-linked Sepharose beads were treated with laccase-TEMPO system for oxidation of the primary alcohol groups on the sugar moieties. Optimal activation conditions using Trametes versicolor laccase were at pH 5 and 22 degrees C, giving an aldehyde content of 55 mu mol g(-1) Sepharose with 28 units g(-1) of laccase and 12.5 mM TEMPO. The activated Sepharose was used for immobilization of trypsin as model protein. Highest degree of immobilization was obtained at pH 10.5 but the activity yield was only 31% of that loaded on the gel. The yield of gel bound trypsin activity was increased to 76% (corresponding to about 43 U g(-1) Sepharose) when the immobilization was performed in the presence of trypsin inhibitor, benzamidine. The immobilization yields were comparable to that obtained on the matrix activated using sodium periodate (containing 72 mu mol aldehyde per g Sepharose). Recycling and storage of the immobilized trypsin preparations showed high stability of the enzyme bound to laccase-TEMPO activated gel. (C) 2010 Elsevier B.V. All rights reserved.
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| 18. |
- Monjane, Julião A., et al.
(författare)
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Leishmanicidal activity of onopordopicrin isolated from the leaves of Brachylaena discolor
- 2018
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Ingår i: Tropical Journal of Natural Product Research. - : University of Benin. - 2616-0684 .- 2616-0692. ; 2:7, s. 328-331
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Tidskriftsartikel (refereegranskat)abstract
- Brachylaena discolor (Asteraceae) is a medicinal plant used in Mozambique to treat stomachache, tuberculosis, and diabetes. To discover new lead compounds with leishmanicidal activity, a methanolic extract of the leaves of this plant was investigated. Through fractionation, employing several chromatographic methods, two sesquiterpene lactones onopordopicrin (1) and its germacronolide epoxide derivative (2), together with other ten know phenolic compounds derivatives (3-12) were isolated. The structures of the isolated compounds were determined by spectroscopic methods, mainly 1D and 2D NMR experiments, as well as by comparing their spectroscopic data as reported in the literature. Compounds 1 and 2 were evaluated for their leishmanicidal activity using the Colorimetric method-XXT. Compound 1 showed a significant leishmanicidal activity against Leishmania amazonensis and L. braziliensis (IC50 values 39.6 and 27.9 μM, respectively) as compared to miltefosine (12.5 and 12.0 μM, respectively), a currently used agent to treat leishmaniosis. While compound 2 was inactive against both stains tested with IC50 values >50μM compared with the same agent. Compounds 3-12 were not assayed for leishmanicidal activity. This is the first study reporting the above-mentioned activity of onopordopicrin (1). The results could suggest that compound 1 is a promising lead structure to treat leishmaniosis.
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| 19. |
- Porta, Miquel, et al.
(författare)
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Plasma concentrations of persistent organic pollutants and pancreatic cancer risk
- 2022
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Ingår i: International Journal of Epidemiology. - : Oxford University Press. - 0300-5771 .- 1464-3685. ; 51:2, s. 479-490
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Tidskriftsartikel (refereegranskat)abstract
- Background: Findings and limitations of previous studies on persistent organic pollutants (POPs) and pancreatic cancer risk support conducting further research in prospective cohorts.Methods: We conducted a prospective case-control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Participants were 513 pancreatic cancer cases and 1020 matched controls. Concentrations of 22 POPs were measured in plasma collected at baseline.Results: Some associations were observed at higher concentrations of p, p'-DDT, trans-nonachlor, β-hexachlorocyclohexane and the sum of six organochlorine pesticides and of 16 POPs. The odds ratio (OR) for the upper quartile of trans-nonachlor was 1.55 (95% confidence interval 1.06-2.26; P for trend = 0.025). Associations were stronger in the groups predefined as most valid (participants having fasted >6 h, with microscopic diagnostic confirmation, normal weight, and never smokers), and as most relevant (follow-up ≥10 years). Among participants having fasted >6 h, the ORs were relevant for 10 of 11 exposures. Higher ORs were also observed among cases with microscopic confirmation than in cases with a clinical diagnosis, and among normal-weight participants than in the rest of participants. Among participants with a follow-up ≥10 years, estimates were higher than in participants with a shorter follow-up (for trans-nonachlor: OR = 2.14, 1.01 to 4.53, P for trend = 0.035). Overall, trans-nonachlor, three PCBs and the two sums of POPs were the exposures most clearly associated with pancreatic cancer risk.Conclusions: Individually or in combination, most of the 22 POPs analysed did not or only moderately increased the risk of pancreatic cancer.
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| 20. |
- Santander, Mylena D., et al.
(författare)
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New insights into the six decades of Mesa's hypothesis of chromosomal evolution in Ommexechinae grasshoppers (Orthoptera: Acridoidea)
- 2021
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Ingår i: Zoological Journal of the Linnean Society. - : Oxford University Press. - 0024-4082 .- 1096-3642. ; 193:4, s. 1141-1155
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Tidskriftsartikel (refereegranskat)abstract
- In Acridoidea grasshoppers, chromosomal rearrangements are frequently found as deviations from the standard acrocentric karyotype (2n = 23 male/24 female, FN = 23 male/24 female) in either phylogenetically unrelated species or shared by closely related ones, i.e. genus. In the South American subfamily Ommexechinae, most of the species show a unique karyotype (2n = 23 male/24 female, FN = 25 male/26 female) owing to the occurrence of a large autosomal pair (L-1) with submetacentric morphology. In the early 1960s, Alejo Mesa proposed the hypothesis of an ancestral pericentric inversion to explain this karyotype variation. Furthermore, in Ommexechinae, extra chromosomal rearrangements (e.g. centric fusions) are recorded between the ancestral X chromosome and autosomes that originated the so-called neo-sex chromosomes. However, the evolutionary significance of the pericentric inversions and centric fusions in Ommexechinae remains poorly explored. Aiming for a better understanding of chromosomal evolution in Ommexechinae, we performed a detailed cytogenetic analysis in five species. Our findings support the hypothesis about the occurrence of an early pericentric inversion in the ancestor of Ommexechinae. Moreover, our results show a complex karyotype diversification pattern due to several chromosome rearrangements, variations in heterochromatin and repetitive DNA dynamics. Finally, the chromosomal mapping of U2 snDNA in L-1 provided new insights about the morphological evolution of this autosomal pair and revealed unnoticed chromosome reorganizations.
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| 21. |
- Solomon, Getachew
(författare)
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Engineering inorganic nanostructured composites for boosting H2 and O2 evolution reactions
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hydrogen is considered a promising energy source with zero emission of CO2; it can provide higher energy density compared to other sources of energy. The amount at which H2 is produced, and the method of production need further improvement for the advancement of hydrogen energy technologies. Water electrolysis using renewable energy sources such as electrical, solar, and wind energy is one of the alternative technologies that can produce pure H2. However, water electrolysis itself is not an easy process, it requires a highly active catalyst capable of converting water into hydrogen, and oxygen.This Ph.D. dissertation mainly focuses on developing efficient, robust, and low-cost catalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and Oxygen reduction reaction (ORR). The work describes different strategies for improving the performance of the catalyst, such as creating nanocomposite, Nobel metal decoration, core-shell structures, hierarchical nanostructure, and cocatalyst and protective layers, which are vital for improving the efficiency of the catalyst. Consequently :Nanocomposites composed of Ag2S nanoparticle, MoS2, and reduced graphene oxide (RGO) flake, with a 0D/2D/2D interface were synthesized. Ag2S nanoparticles were homogeneously distributed and embedded in a layer of semi-crystalline MoS2 nanosheets. The ternary catalyst results in a superior performance due to the intimate contact created by the 2D-2D interface (MoS2/RGO) and due to the uniformly grown Ag2S nanoparticles, which provides the ease of hydrogen adsorption by modulating the electronic properties, and exposure of highly rich active sitesNobel metal decorated (Ag-decorated vertically aligned MoS2 nanoflakes) were developed and investigated for OER and ORR. Results of this work revealed that, due to the presence of silver, the catalyst shows more than 1.5 times an increase in the roughness-normalized rate of OER. Based on the rate constant values obtained during the ORR test, Ag-MoS2 proceeds through a mixed 4 electron and a 2 + 2 serial route reduction mechanism, suggesting that the presence of silver decreases the electron transfer number and increases the peroxide yield. A core-shell structure of hydrous NiMoO4 micro rods conformally covered by Co3O4 nanoparticles was developed and employed as an OER catalyst, showing a remarkable catalytic activity towards OER with a record low overpotential of 120 mV at 10 mA/cm2. Here, the strong interactions between core (hydrated NiMoO4) and shell (Co3O4) help to tune the electronic properties by modifying the active sites densities of the surface.A hierarchical nanostructure composed of NiMoO4 nanorods and MoS2 nanosheets was synthesized on interconnected nickel foam substrates. The as-prepared hierarchical structure exhibits excellent OER performance due to its numerous exposed active sites for adsorbing oxygen intermediates which are beneficial for promoting the enhancement of the OER catalytic performanceCu2O photocathode protected by a very thin layer of TiO2 and an amorphous Vox were synthesized and used for HER, with aim of improving the photostability of Cu2O. Photooxidation of Cu2O nanowires are minimized by growing TiO2 protective layer and an amorphous VOx cocatalyst. After optimization of the overlayer and the cocatalyst, the photoelectrode exhibits a stable photocurrent density for an extended illumination time. Besides, advanced characterization tools were used for tracking ORR reaction intermediates and OER active sites. RRDE, Operando Raman, and synchrotron-based photoemission spectroscopy analysis were utilized together with Post OER characterization tools to reveal the reason behind the higher catalytic activity of the catalyst. In summary, the presented outcomes can significantly contribute to the fundamental insight towards improving the efficiency of HER, OER, and ORR catalyst, by offering a clear and in-depth understanding of the preparation and characterization of cheap and efficient catalysts.
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| 22. |
- Terrazas, Paola, et al.
(författare)
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SAR:s for the Antiparasitic Plant Metabolite Pulchrol. 1. The Benzyl Alcohol Functionality
- 2020
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Ingår i: Molecules (Basel, Switzerland). - : MDPI AG. - 1420-3049. ; 25:13
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Tidskriftsartikel (refereegranskat)abstract
- Pulchrol (1) is a natural benzochromene isolated from the roots of Bourreria pulchra, shown to possess potent antiparasitic activity towards both Leishmania and Trypanozoma species. As it is not understood which molecular features of 1 are important for the antiparasitic activity, several analogues were synthesized and assayed. The ultimate goal is to understand the structure-activity relationships (SAR:s) and create a QSAR model that can be used for the development of clinically useful antiparasitic agents. In this study, we have synthesized 25 2-methoxy-6,6-dimethyl-6H-benzo[c]chromen analogues of 1 and its co-metabolite pulchral (5a), by semi-synthetic procedures starting from the natural product pulchrol (1) itself. All 27 compounds, including the two natural products 1 and 5a, were subsequently assayed in vitro for antiparasitic activity against Trypanozoma cruzi, Leishmania brasiliensis and Leishmania amazoniensis. In addition, the cytotoxicity in RAW cells was assayed, and a selectivity index (SI) for each compound and each parasite was calculated. Several compounds are more potent or equi-potent compared with the positive controls Benznidazole (Trypanozoma) and Miltefosine (Leishmania). The compounds with the highest potencies as well as SI-values are esters of 1 with various carboxylic acids.
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| 23. |
- Terrazas, Paola, et al.
(författare)
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SARs for the antiparasitic plant metabolite pulchrol. : 3. Combinations of new substituents in A/B-rings and A/C-rings
- 2021
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Ingår i: Molecules. - : MDPI AG. - 1420-3049. ; 26:13
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Tidskriftsartikel (refereegranskat)abstract
- The natural products pulchrol and pulchral, isolated from the roots of the Mexican plant Bourreria pulchra, have previously been shown to possess an antiparasitic activity toward Trypanosoma cruzi, Leishmania braziliensis and L. amazonensis, protozoa responsible for the Chagas disease and leishmaniasis. These infections have been classified as neglected diseases, and still require the development of safer and more efficient alternatives to their current treatments. Recent SAR stud-ies, based on the pulchrol scaffold, showed which effect the exchanges of its substituents have on the antileishmanial and antitrypanosomal activity. Many of the analogues prepared were shown to be more potent in vitro than pulchrol and the current drugs used to treat Leishmaniasis and the Chagas disease (Miltefosine and Benznidazole respectively). Moreover, indications of some of the possible interactions that may take place in the binding sites were also identified. In this study, 12 analogues with modifications at two or three different positions in two of the three rings were prepared by synthetic and semi-synthetic procedures. The molecules were assayed in vitro to-ward T. cruzi epimastigotes, L. braziliensis promastigotes and L. amazonensis promastigotes. Some compounds had higher antiparasitic activity than the parent compound pulchrol, and in some cases even Benznidazole and Miltefosine. The best combinations in this subset are with carbonyl functionalities in the A-ring and isopropyl groups in the C-ring, as well as with alkyl substituents in both the A- and C-rings combined with a hydroxyl group in position 1 (C-ring). The latter corresponds to cannabinol, which was shown to be potent toward all parasites.
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| 24. |
- Toledo, Rodrigo A., et al.
(författare)
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Consensus Statement on next-generation-sequencing-based diagnostic testing of hereditary phaeochromocytomas and paragangliomas
- 2017
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Ingår i: Nature Reviews Endocrinology. - : NATURE PUBLISHING GROUP. - 1759-5029 .- 1759-5037. ; 13:4, s. 233-247
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Tidskriftsartikel (refereegranskat)abstract
- Phaeochromocytomas and paragangliomas (PPGLs) are neural-crest-derived tumours of the sympathetic or parasympathetic nervous system that are often inherited and are genetically heterogeneous. Genetic testing is recommended for patients with these tumours and for family members of patients with hereditary forms of PPGLs. Due to the large number of susceptibility genes implicated in the diagnosis of inherited PPGLs, next-generation sequencing (NGS) technology is ideally suited for carrying out genetic screening of these individuals. This Consensus Statement, formulated by a study group comprised of experts in the field, proposes specific recommendations for the use of diagnostic NGS in hereditary PPGLs. In brief, the study group recommends target gene panels for screening of germ line DNA, technical adaptations to address different modes of disease transmission, orthogonal validation of NGS findings, standardized classification of variant pathogenicity and uniform reporting of the findings. The use of supplementary assays, to aid in the interpretation of the results, and sequencing of tumour DNA, for identification of somatic mutations, is encouraged. In addition, the study group launches an initiative to develop a gene-centric curated database of PPGL variants, with annual re-evaluation of variants of unknown significance by an expert group for purposes of reclassification and clinical guidance.
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