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281 results on '"de Boni L"'

7. Effects of 30 days bed rest and exercise countermeasures on PBMC bioenergetics

Author

Buescher, F.‐M., primary, Schmitz, M. T., additional, Frett, T., additional, Kramme, J., additional, de Boni, L., additional, Elmenhorst, E. M., additional, Mulder, E., additional, Moestl, S., additional, Heusser, K., additional, Frings‐Meuthen, P., additional, Jordan, J., additional, Rittweger, J., additional, and Pesta, D., additional

Published
2024
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32. Analysis of α-synuclein species enriched from cerebral cortex of humans with sporadic dementia with lewy bodies

Author

Sanderson, J.B., De, S., Jiang, H., Rovere, M., Jin, M., Zaccagnini, L., Hays Watson, A., De Boni, L., Lagomarsino, V.N., Young-Pearse, T.L., Liu, X., Pochapsky, T.C., Hyman, B.T., Dickson, D.W., Klenerman, D., Selkoe, D.J., and Bartels, T.

Abstract

Since researchers identified α-synuclein as the principal component of Lewy bodies and Lewy neurites, studies have suggested that it plays a causative role in the pathogenesis of dementia with Lewy bodies and other ‘synucleinopathies’. While α-synuclein dyshomeostasis likely contributes to the neurodegeneration associated with the synucleinopathies, few direct biochemical analyses of α-synuclein from diseased human brain tissue currently exist. In this study, we analysed sequential protein extracts from a substantial number of patients with neuropathological diagnoses of dementia with Lewy bodies and corresponding controls, detecting a shift of cytosolic and membrane-bound physiological α-synuclein to highly aggregated forms. We then fractionated aqueous extracts (cytosol) from cerebral cortex using non-denaturing methods to search for soluble, disease-associated high molecular weight species potentially associated with toxicity. We applied these fractions and corresponding insoluble fractions containing Lewy-type aggregates to several reporter assays to determine their bioactivity and cytotoxicity. Ultimately, high molecular weight cytosolic fractions enhances phospholipid membrane permeability, while insoluble, Lewy-associated fractions induced morphological changes in the neurites of human stem cell-derived neurons. While the concentrations of soluble, high molecular weight α-synuclein were only slightly elevated in brains of dementia with Lewy bodies patients compared to healthy, age-matched controls, these observations suggest that a small subset of soluble α-synuclein aggregates in the brain may drive early pathogenic effects, while Lewy body-associated α-synuclein can drive neurotoxicity.

Published
2020

34. Heterodyne Z-scan measurements of slow absorbers

Author

Guedes, I., Misoguti, L., De Boni, L., and Zilio, S. C.

Subjects
Nonlinear optics -- Research, Optical measurements -- Methods, Physics
Abstract

The article describes a newly discovered single-beam heterodyne Z-scan method, which is commonly being used for the measurement of the slow response nonlinear refraction of absorbers exhibiting excellent sensitivity. The different parasitic linear effects can be easily eliminated by increasing the sensitivity of the absorbers.

Published
2007

46. Experimental and theoretical study of two-photon absorption in nitrofuran derivatives: Promising compounds for photochemotherapy.

Author

De Boni, L., Correa, D. S., Silva, D. L., Gonçalves, P. J., Zilio, S. C., Parra, G. G., Borissevitch, I. E., Canuto, S., and Mendonca, C. R.

Subjects
*PHOTOCHEMOTHERAPY, *ABSORPTION spectra, *QUINOLINE, *DENSITY functionals, *MOLECULAR spectroscopy, *EXCITON theory, *FURANS, *TWO-photon absorbing materials
Abstract

We report experimental and theoretical studies of the two-photon absorption spectrum of two nitrofuran derivatives: nitrofurantoine, (1-(5-nitro-2-furfurilideneamine)-hidantoine) and quinifuryl, 2-(5′-nitro-2′-furanyl)ethenyl-4-{N-[4′-(N,N-diethylamino)-1′-methylbutyl]carbamoyl} quinoline. Both molecules are representative of a family of 5-nitrofuran-ethenyl-quinoline drugs that have been demonstrated to display high toxicity to various species of transformed cells in the dark. We determine the two-photon absorption cross-section for both compounds, from 560 to 880 nm, which present peak values of 64 GM for quinifuryl and 20 GM for nitrofurantoine (1 GM = 1×10-50cm4.s.photon-1). Besides, theoretical calculations employing the linear and quadratic response functions were carried out at the density functional theory level to aid the interpretations of the experimental results. The theoretical results yielded oscillator strengths, two-photon transition probabilities, and transition energies, which are in good agreement with the experimental data. A higher number of allowed electronic transitions was identified for quinifuryl in comparison to nitrofurantoine by the theoretical calculations. Due to the planar structure of both compounds, the differences in the two-photon absorption cross-section values are a consequence of their distinct conjugation lengths. [ABSTRACT FROM AUTHOR]

Published
2011
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47. Excited state absorption spectrum of chlorophyll a obtained with white-light continuum.

Author

De Boni, L., Correa, D. S., Pavinatto, F. J., dos Santos Jr., D. S., and Mendon&#00xE7;a, C. R.

Subjects
*ABSORPTION spectra, *CHLOROPHYLL, *PHOTONICS, *ABSORPTION, *ENERGY levels (Quantum mechanics), *MOLECULES, *MOLECULAR dynamics
Abstract

The study of excited state properties of chlorophyll a is a subject of foremost interest, given that it plays important roles in biological process and has also been proposed for applications in photonics. This work reports on the excited state absorption spectrum of chlorophyll a solution from 460 to 700 nm, obtained through the white-light continuum Z-scan technique. Saturation of absorption was observed due to the ground state depletion, induced by the white-light continuum region that is resonant with the Q band of chlorophyll a. The authors also observed reverse saturation of absorption related to the excitation from the first excited state to a higher energy level for wavelengths below 640 nm. An energy-level diagram, based on the electronic states of chlorophyll a, was employed to interpret their results, revealing that more states than the ones related to the Q and B bands participate in the excited state absorption of this molecule. [ABSTRACT FROM AUTHOR]

Published
2007
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48. Resonant nonlinear absorption in Zn-phthalocyanines

Author

De Boni, L., Piovesan, E., Gaffo, L., and Mendonca, C.R.

Subjects
Zinc compounds -- Spectra, Excited state chemistry -- Research, Dimethyl sulfoxide -- Spectra, Chemicals, plastics and rubber industries
Abstract

Numerous single pulse and pulse train Z-scan techniques are employed to explain the resonant nonlinear absorption dynamics of zinc (Zn)-phthalocyanines in dimethyl sulfoxide (DMSO). The excited singlet state absorption cross-section determined is shown to be higher than the ground state one.

Published
2008

49. Excited state dynamics of meso-tetra(sulphonatophenyl) metalloporphyrins

Author

Goncalves, P.J., De Boni, L., Borissevitch, I.E., and Zilio, S.C.

Subjects
Porphyrins -- Chemical properties, Porphyrins -- Electric properties, Chemical reactions -- Analysis, Chemicals, plastics and rubber industries
Abstract

A Z-scan technique at 532 nm with different pulses of a Q-switched and model locked laser was used to explore the excited state dynamics of [Zn.sup.2+], [Fe.sup.3+], and [Mn.sup.3+] meso-tetra(sulfonatophenyl) porphyrin complexes. The data obtained for ground state cross-sections provide insight into the singlet and triplet excited state cross-sections, fluorescence, inter-system crossing, and internal conversion quantum yield and characteristic times.

Published
2008

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