Vibrational spectroscopy techniques, such as Fourier-transform infrared (FTIR) and Raman spectroscopy, have been successful methods for studying the interaction of light with biological materials and ...facilitating novel cell biology analysis. Spectrochemical analysis is very attractive in disease screening and diagnosis, microbiological studies and forensic and environmental investigations because of its low cost, minimal sample preparation, non-destructive nature and substantially accurate results. However, there is now an urgent need for multivariate classification protocols allowing one to analyze biologically derived spectrochemical data to obtain accurate and reliable results. Multivariate classification comprises discriminant analysis and class-modeling techniques where multiple spectral variables are analyzed in conjunction to distinguish and assign unknown samples to pre-defined groups. The requirement for such protocols is demonstrated by the fact that applications of deep-learning algorithms of complex datasets are being increasingly recognized as critical for extracting important information and visualizing it in a readily interpretable form. Hereby, we have provided a tutorial for multivariate classification analysis of vibrational spectroscopy data (FTIR, Raman and near-IR) highlighting a series of critical steps, such as preprocessing, data selection, feature extraction, classification and model validation. This is an essential aspect toward the construction of a practical spectrochemical analysis model for biological analysis in real-world applications, where fast, accurate and reliable classification models are fundamental.
Actinomycetes are known to produce numerous secondary bioactive metabolites of pharmaceutical interest. The purpose of this study was to isolate, characterize, and investigate the antibacterial, ...antifungal, and anticancer activities of metabolites produced by Actinobacteria isolated from the rhizosphere of
Paullinia cupana
. The Actinobacteria was identified as
Streptomyces hygroscopicus
ACTMS-9H. Based on a bioguided study, the methanolic biomass extract obtained from submerged cultivation had the most potent antibacterial, antifungal, and cytotoxic activities. This extract was partitioned with
n
-hexane, ethyl acetate, and 2-butanol. Elaiophylin was isolated from the methanolic biomass extract, and its molecular formula was determined (C
54
H
88
O
18
) based on
1
H and
13
C NMR, IR and MS analyses. The 2-butanol phase was fractionated into four fractions (EB1, EB2A, EB2B, and EB3M). Chemical prospecting indicated the presence of alkaloids, saponins, and reducing sugars in the methanolic extract and 2-butanol phase. The elaiophylin displayed anticancer activity in HEp-2 and HL-60 cells with an IC
50
of 1 μg/mL. The EB1 fraction was selectively toxic to HL-60 cells with IC
50
of 9 ng/mL. Bioautography showed that the EB1 fraction contained an alkaloid with antibacterial and antifungal activities (MIC values ≤1.9 and <3.9 μg/mL, respectively). In conclusion, the EB1 fraction and elaiophylin of
S. hygroscopicus
have potent antimicrobial, antifungal, and anticancer activities.
Full text
Available for:
CEKLJ, DOBA, EMUNI, FZAB, GEOZS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In the past decades, the physicochemical properties of electron donor–acceptor, EDA, complexes (also called charge-transfer, CT, complexes) have been extensively studied, although their synthetic ...applications have been somewhat limited. However, in recent years, this scenario has started to change as an increasing number of examples have been reported. In this regard, this review aims to present and discuss the main aspects associated with the physicochemical properties of these complexes and a selection of synthetic photochemical applications in organic chemistry.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
Environmental monitoring plays a central role in diagnosing climate and management impacts on natural and agricultural systems; enhancing the understanding of hydrological processes; optimizing the ...allocation and distribution of water resources; and assessing, forecasting, and even preventing natural disasters. Nowadays, most monitoring and data collection systems are based upon a combination of ground-based measurements, manned airborne sensors, and satellite observations. These data are utilized in describing both small- and large-scale processes, but have spatiotemporal constraints inherent to each respective collection system. Bridging the unique spatial and temporal divides that limit current monitoring platforms is key to improving our understanding of environmental systems. In this context, Unmanned Aerial Systems (UAS) have considerable potential to radically improve environmental monitoring. UAS-mounted sensors offer an extraordinary opportunity to bridge the existing gap between field observations and traditional air- and space-borne remote sensing, by providing high spatial detail over relatively large areas in a cost-effective way and an entirely new capacity for enhanced temporal retrieval. As well as showcasing recent advances in the field, there is also a need to identify and understand the potential limitations of UAS technology. For these platforms to reach their monitoring potential, a wide spectrum of unresolved issues and application-specific challenges require focused community attention. Indeed, to leverage the full potential of UAS-based approaches, sensing technologies, measurement protocols, postprocessing techniques, retrieval algorithms, and evaluation techniques need to be harmonized. The aim of this paper is to provide an overview of the existing research and applications of UAS in natural and agricultural ecosystem monitoring in order to identify future directions, applications, developments, and challenges.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Malgré les critiques et les réserves dont il est l’objet aujourd’hui, Louis Pasteur peut être considéré comme l’un des scientifiques les plus importants de ces deux derniers siècles en matière de ...santé publique, même si les apports des nombreux hommes de science qui l’ont précédé ont largement contribué aux succès qu’il obtint sans trop se soucier des règles de déontologie et d’éthique actuellement en vigueur dans le monde de la recherche et de la médecine. Il a mis définitivement à bas, par ses expériences, la « théorie de la génération spontanée » en vigueur depuis l’Antiquité, validé celle « des germes ou microbes », édicté les premières règles de l’asepsie tout en inspirant celles de l’antisepsie appliquée par Joseph Lister et mit au point un certain nombre de vaccinations en médecine vétérinaire puis humaine, notamment celle contre la rage, ce qui le rendit célèbre dans le monde entier. Tout cela ne s’est pas fait sans difficulté, et Pasteur s’est heurté pendant une grande partie de sa vie à l’incompréhension de ses contemporains et à l’hostilité du monde médical auquel il n’appartenait pas. Les auteurs commentent dans ce texte le film L’Histoire de Louis Pasteur de William Dieterle, tourné en 1936, en s’appuyant sur les connaissances acquises depuis cette date et en faisant la part du réel et de l’imaginé.
Spectroscopic techniques such as Fourier-transform infrared (FTIR) spectroscopy are used to study interactions of light with biological materials. This interaction forms the basis of many analytical ...assays used in disease screening/diagnosis, microbiological studies, and forensic/environmental investigations. Advantages of spectrochemical analysis are its low cost, minimal sample preparation, non-destructive nature and substantially accurate results. However, an urgent need exists for repetition and validation of these methods in large-scale studies and across different research groups, which would bring the method closer to clinical and/or industrial implementation. For this to succeed, it is important to understand and reduce the effect of random spectral alterations caused by inter-individual, inter-instrument and/or inter-laboratory variations, such as variations in air humidity and CO
levels, and aging of instrument parts. Thus, it is evident that spectral standardization is critical to the widespread adoption of these spectrochemical technologies. By using calibration transfer procedures, in which the spectral response of a secondary instrument is standardized to resemble the spectral response of a primary instrument, different sources of variation can be normalized into a single model using computational-based methods, such as direct standardization (DS) and piecewise direct standardization (PDS); therefore, measurements performed under different conditions can generate the same result, eliminating the need for a full recalibration. Here, we have constructed a protocol for model standardization using different transfer technologies described for FTIR spectrochemical applications. This is a critical step toward the construction of a practical spectrochemical analysis model for daily routine analysis, where uncertain and random variations are present.
This study aimed to evaluate the inhibitory effects of phenolic‐rich extracts from acerola (Malpighia emarginata D.C., PEA), cashew apple (Anacardium occidentale L., PEC) and mango (Mangifera indica ...L., PEM) by‐products on distinct enterotoxigenic Escherichia coli (ETEC) strains. The capability of PEA and PEC of impairing various physiological functions of ETEC strains was investigated with multiparametric flow cytometry. Procyanidin B2, myricetin and p‐coumaric acid were the major phenolic compounds in PEA, PEC and PEM, respectively. PEA and PEC had lower minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) (MIC: 31·25 mg ml−1; MBC: 62·5 mg ml−1) on ETEC strains than PEM (MIC and MIC: >1000 mg ml−1). PEA and PEC (15·6, 31·2, 62·5 mg ml−1) caused viable count reductions (P < 0·05) on ETEC strains after 24 h of exposure, notably the ≥3 log reductions caused by 62·5 mg ml−1. The 24 h exposure of ETEC strains to PEA and PEC (31·2, 62·5 mg ml−1) led to high sizes of cell subpopulations with concomitant impairments in cell membrane polarization and permeability, as well as in enzymatic, respiratory and efflux activities. PEA and PEC are effective in inhibiting ETEC through a multi‐target action mode with disturbance in different physiological functions.
Significance and Impact of the Study: Enterotoxigenic Escherichia coli (ETEC) is one of the main causes of diarrhoea in humans and animals. The increasing resistance of ETEC strains to clinically relevant antibiotics has prompt the necessity to search for novel substances with inhibitory efficacy. This is the first study showing the capability of phenolic‐rich extracts of acerola and cashew apple by‐products causing the inhibition of distinct ETEC strains, with disturbance of various physiological functions, indicating these substances as potential antimicrobials to be exploited in solutions to control ETEC in humans and animals.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Recent research trends now offer new opportunities for developing the next generations of label‐free biochemical sensors using graphene and other two‐dimensional materials. While the physics of ...graphene transistors operated in electrolyte is well grounded, important chemical challenges still remain to be addressed, namely the impact of the chemical functionalizations of graphene on the key electrical parameters and the sensing performances. In fact, graphene – at least ideal graphene – is highly chemically inert. The functionalizations and chemical alterations of the graphene surface – both covalently and non‐covalently – are crucial steps that define the sensitivity of graphene. The presence, reactivity, adsorption of gas and ions, proteins, DNA, cells and tissues on graphene have been successfully monitored with graphene. This review aims to unify most of the work done so far on biochemical sensing at the surface of a (chemically functionalized) graphene field‐effect transistor and the challenges that lie ahead. The authors are convinced that graphene biochemical sensors hold great promise to meet the ever‐increasing demand for sensitivity, especially looking at the recent progresses suggesting that the obstacle of Debye screening can be overcome.
The work done so far on biochemical sensing at the surface of a (chemically functionalized) graphene field‐effect transistor and the challenges that lie ahead, including the recent progress in meeting the ever increasing demand for sensitivity by overcoming the obstacle of Debye screening, are discussed.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Nanoemulsions are increasingly gaining importance in the development of topically applied medicine and cosmetic products because their small droplets favor the penetration rates of active compounds ...into the body. In this scenario, the measurements of their diffusion rates as well as eventual physicochemical changes in the target tissues are of utmost importance. It is also recognized that the use of natural surfactants can avoid allergic reactions as frequently observed for synthetic products. The natural saponins extracted from Sapindus Saponaria have the property of forming foam and are exploited as biocompatible and biodegradable, while cellulose nanocrystals are known to increase the stability of a formulation avoiding the coalescence of drops at the interface. Therefore, nanoemulsions combining natural saponins and cellulose nanocrystals are promising systems that may facilitate greater diffusion rates of molecules into the skin, being candidates to substitute synthetic formulations. This study applied the Photoacoustic Spectroscopy technique to measure the diffusion rates and the physicochemical properties of nanoemulsified formulations containing saponins and cellulose nanocrystals topically applied to the skin. The ex vivo study combined the first-time photoacoustic measurements performed in both ultraviolet-visible and mid-infrared spectral regions. The toxicity of these formulations in L929 cells was also evaluated. The results showed that the formulations were able to propagate throughout the skin to a depth of approximately 756 μm, reaching the dermal side. The non-observation of absorbing band shifting or new bands in the FTIR spectra suggests that there were no structural changes in the skin as well as in the formulations after the nanoemulsions administration. The cytotoxicity results showed that the increase of cellulose nanocrystals concentration decreased cellular toxicity. In conclusion, the results demonstrated the advantage of combining photoacoustic methods in the ultraviolet-visible and mid-infrared spectral regions to analyze drug diffusion and interaction with the skin tissues. Both methods complement each other, allowing the confirmation of the nanoemulsion diffusion through the skin and also suggesting there were no detectable physicochemical changes in the tissues. Formulations stabilized with saponins and cellulose nanocrystals showed great potential for the development of topically administered cosmetics and drugs.
Display omitted
•Ex vivo photoacoustic study was done for the first time in the UV–Vis and MIR regions.•Diffusion rates and formulation interaction with skin were successfully investigated.•The formulations propagated throughout the skin, reaching the dermal side.•The nanoemulsions are safe from adverse toxicity effects, evaluated in L929 cells.•Saponin and cellulose nanocrystal nanoemulsions can be cosmetic or drug vehicles.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Considerable interest in the relationship between biodiversity and disease has recently captured the attention of the research community, with important public policy implications. In particular, ...malaria in the Amazon region is often cited as an example of how forest conservation can improve public health outcomes. However, despite a growing body of literature and an increased understanding of the relationship between malaria and land use / land cover change (LULC) in Amazonia, contradictions have emerged. While some studies report that deforestation increases malaria risk, others claim the opposite. Assessing malaria risk requires examination of dynamic processes among three main components: (i) the environment (i.e. LULC and landscape transformations), (ii) vector biology (e.g. mosquito species distributions, vector activity and life cycle, plasmodium infection rates), and (iii) human populations (e.g. forest-related activity, host susceptibility, movement patterns). In this paper, we conduct a systematic literature review on malaria risk and deforestation in the Amazon focusing on these three components. We explore key features that are likely to generate these contrasting results using the reviewed articles and our own data from Brazil and Peru, and conclude with suggestions for productive avenues in future research.
This article is part of the themed issue ‘Conservation, biodiversity and infectious disease: scientific evidence and policy implications'.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
PDF
