Hesham El-Askary

A multisensor approach to dust storm monitoring over the Nile Delta

This work analyzes several remote sensing instrument capabilities in monitoring dust storms. Multisensor data analysis is carried out to study the behavior of dust particles at different wavelengths. A technique based on a combination of optical and microwave sensing of dust storms, using the Moderate Resolution Imaging Spectrometer (MODIS) and the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) respectively, is found to be particularly useful.

Rice bran extract protects from mitochondrial dysfunction in guinea pig brains

Mitochondrial dysfunction plays a major role in the development of age-related neurodegenerative diseases and recent evidence suggests that food ingredients can improve mitochondrial function. In the current study we investigated the effects of feeding a stabilized rice bran extract (RBE) on mitochondrial function in the brain of guinea pigs. Key components of the rice bran are oryzanols, tocopherols and tocotrienols, which are supposed to have beneficial effects on mitochondrial function. Concentrations of α-tocotrienol and γ-carboxyethyl hydroxychroman (CEHC) but not γ-tocotrienol were significantly elevated in brains of RBE fed animals and thus may have provided protective properties. Overall respiration and mitochondrial coupling were significantly enhanced in isolated mitochondria, which suggests improved mitochondrial function in brains of RBE fed animals. Cells isolated from brains of RBE fed animals showed significantly higher mitochondrial membrane potential and ATP levels after sodium nitroprusside (SNP) challenge indicating resistance against mitochondrial dysfunction. Experimental evidence indicated increased mitochondrial mass in guinea pig brains, e.g. enhanced citrate synthase activity, increased cardiolipin as well as respiratory chain complex I and II and TIMM levels. In addition levels of Drp1 and fis1 were also increased in brains of guinea pigs fed RBE, indicating enhanced fission events. Thus, RBE represents a potential nutraceutical for the prevention of mitochondrial dysfunction and oxidative stress in brain aging and neurodegenerative diseases.

Dust storm and black cloud influence on aerosol optical properties over Cairo and the Greater Delta region, Egypt

We have analysed aerosol and cloud properties, obtained from moderate resolution imaging spectroradiometer (MODIS) data, over Cairo and the Greater Delta region during the spring months of March, April and May (MAM) and the autumn months of September, October and November (SON) in the years 2004, 2005 and 2006. During these two time periods, we have examined dust storms, dense haze and a smog‐like phenomenon known, locally, as the ‘black cloud’. Our work is based on the aerosol optical depth (AOD), fine mode fraction (FMF) and cloud properties (cloud top temperature (CTT), cloud top pressure (CTP), atmospheric infrared sounder (AIRS) temperature profiles and water vapour column). High anomalous water vapour is detected, which we believe is as a result of pollution aerosols rather than dust and is hence acting as cloud condensation nuclei (CCN). The CTT shows increasing and decreasing trends, corresponding to the dust occurring at ∼750–800 hpa and pollution episodes at >900 hpa, respectively as observed from the CTP. Temperature inversion conditions, as well as adverse weather conditions, contribute to the pollution observed by preventing pollutants from escaping to the higher atmosphere.

Sesquiterpenes from Cymbopogon proximus

In addition to four previously reported compounds: proximadiol (1), 5α-hydroxy-β-eudesmol (2), 1β-hydroxy-β-eudesmol (4) and 1β-hydroxy-α-eudesmol (5), two new sesquiterpenes, 5α-hydroperoxy-β-eudesmol (3) and 7α,11-dihydroxy-cadin-10(14)-ene (6) were isolated from the unsaponifiable fraction of the petroleum ether extract of Cymbopogon proximus STAPF. Isolation of compounds 2, 4 and 5 from the genus Cymbopogon is reported for the first time. The structure elucidation of these compounds was based primarily on 1D and 2D-NMR analyses.

Terpenoids from Cleome droserifolia (Forssk.) Del.

A new diacetyl triterpene lactone, drosericarpone (2), was isolated from the hexane extract of the herb Cleome droserifolia, together with buchariol (1, a sesquiterpene oxide, isolated for the first time from Cleome species) and stigmasterol glucoside (3). The structures of 1-3 were identified by spectroscopic means.

Synergistic Use of Remote Sensing and Modeling for Tracing Dust Storms in the Mediterranean

This study focuses on the detection of the dust source region and monitoring of the transport of the dust plume from its primary outflow to final deposition. The application area is the Sahara desert and the eastern Mediterranean, where two dust events occurred during the period 4–6 February 2009, an unusual event for a winter period. The Aqua-MODIS and OMI observations clearly define the spatial distribution of the dust plumes, while the CALIPSO observations of total attenuated backscatter (TAB) at 532 nm, depolarization ratio (DR), and attenuated color ratio (1064/532 nm) on 5 February 2009 provide a clear view and vertical structure of the dust-laden layer. The dust source region is defined to be near the Chad-Niger-Libyan borders, using satellite observations and model (DREAM) output. This dust plume is vertically extended up to 2.5 km and is observed as a mass plume of dust from surface level to that altitude, where the vertical variation of TAB (0.002 to 0.2) and DR (0.2–0.5) implies dust-laden layer with non-spherical particles. CALIPSO profiles show that after the dust plume reached at its highest level, the dust particles start to be deposited over the Mediterranean and the initial dust plume was strongly attenuated, while features of dust were limited below about 1–1.5 km for latitudes northern of ~36° (Greek territory).

Change detection of coral reef habitat using Landsat-5 TM, Landsat 7 ETM+ and Landsat 8 OLI data in the Red Sea Hurghada, Egypt

Owing to continuing touristic developments in Hurghada, Egypt, several coral reef habitats have suffered major deterioration between 1987 and 2013, either by being bleached or totally lost. Such alterations in coral reef habitats have been well observed in their varying distributions using change detection analysis applied to a Landsat 5 image representing 1987, a Landsat 7 image representing 2000, and a Landsat 8 image representing 2013. Different processing techniques were carried out over the three images, including but not limited to rectification, masking, water column correction, classification, and change detection statistics. The supervised classifications performed over the three scenes show five significant marine-related classes, namely coral, sand subtidal, sand intertidal, macro-algae, and seagrass, in different degrees of abundance. The change detection statistics obtained from the classified scenes of 1987 and 2000 reveal a significant increase in the macro-algae and seagrass classes (93 and 47%, respectively). However, major decreases of 41, 40, and 37% are observed in the sand intertidal, coral, and sand subtidal classes, respectively. On the other hand, the change detection statistics obtained from the classified scenes of 2000 and 2013 revealed increases in sand subtidal and macro-algae classes by 14 and 19%, respectively, while major decreases of 49%, 46% and 74% are observed in the sand intertidal, coral, and seagrass classes, respectively.

Acaricidal activity of Swietenia mahogani and Swietenia macrophylla ethanolic extracts against Varroa destructor in honeybee colonies.

The acaricidal (miticidal) activity of 90% ethanolic extracts of leaves and stem bark of Swietenia mahogani and Swietenia macrophylla were tested against Varroa destructor mite. Four concentrations were used over two different time intervals under laboratory and field conditions. In general, it was noticed that the acaricidal effect based on mortality and LC(50) of all tested extracts against the Varroa mite was concentration and time dependant. The acaricidal action against Varroa mites was relatively the least for the S. macrophylla stem bark extract at 500 ppm concentration after 48 h while it reached 100% and 95% in case of S. mahogani bark and S. macrophylla leaves, respectively. The% infestation with Varroa in colonies treated with the different extracts at various time intervals showed that the rate of infestation decreased to 0.0% after 12 days from the beginning of treatments with 500 ppm of S. mahogani leaves extract compared to 0.79% decrease after treatment with Mitac, a reference drug (60 mg/colony). The rate of infestation in case of treatments with S. mahogani bark, S. macrophylla leaves and S. macrophylla bark was decreased to 0.11%, 2.41% and 1.08%, respectively. The highest reduction was observed with S. mahogani leaves extract followed by S. mahogani bark. All the tested extracts showed less or no effect on honey bees at the different concentrations and at different bioassay times. This study suggested that the use of natural plant extracts or their products as ecofriendly biodegradable agents could be of high value for the control of Varroa mite.

In vivo anti-inflammatory activity of caffeoylquinic acid derivatives from Solidago virgaurea in rats

Abstract Context: Solidago virgaurea L. (Asteraceae) is traditionally used as an anti-inflammatory for the treatment of various symptoms including cystitis. However, little is known concerning the constituents responsible for this activity and the mechanism of their action. Objective: To assess the anti-inflammatory activity of the phenolic-rich fraction of S. virgaurea aerial parts in rats, isolate and assess the activity of the major compounds present. Materials and methods: An HPLC method was developed for the analysis of the phenolic-rich fraction (EtFr). The in vivo anti-inflammatory activity of the EtFr and four isolated compounds (at 25 and 50 mg/kg) were assessed in adult male rats using the carrageenan-induced rat paw oedema model. The levels of the pro-inflammatory cytokines (TNF-α and IL-1β) were measured using ELISA. Results: 3,5-O-Dicaffeoylquinic acid (1), 3,4-O-dicaffeoylquinic acid (2), 3,4,5-O-tricaffeoylquinic acid (3) and 4,5-O-dicaffeoylquinic acid (4) were isolated from EtFr. Compound 3 (50 mg/kg) showed a highly significant activity in inhibiting the oedema volume after 3 h (88% of the activity of indomethacin at 10 mg/kg). The EtFr and the isolated compounds largely inhibited the excessive production of the inflammatory mediators TNF-α and IL-1β. Discussion and conclusion: This is the first report of 3,4,5-tri-O-caffeoylquinic acid (3) in Solidago species. The tricaffeoylquinic acid (3) showed a significantly higher activity than the other three dicaffeoylquinic acids (1, 2, 4) and indomethacin in reduction of TNF-α and IL-1β concentrations (8.44 ± 0.62 and 5.83 ± 0.57 pg/mL compared to 12.60 ± 1.30 and 52.91 ± 5.20 pg/mL induced by indomethacin, respectively).

Bioguided isolation of pentacyclic triterpenes from the leaves of Alstonia scholaris (Linn.) R. Br. growing in Egypt

Ethanolic and aqueous extracts of the leaves and flowers of Alstonia scholaris were evaluated for their antioxidant activity by investigating their effect on blood glutathione levels in alloxan-induced diabetic rats. The ethanolic extract of the leaves was the most active; therefore, its cytotoxicity against HepG2 cells was also tested. Promising GI50 values of 1.96, 4.34 and 4.65 µg mL–1 were observed for the extract, its chloroform and ethyl acetate fractions, respectively. The chloroform active subfraction I (GI50 = 2.97 µg mL–1) yielded betulin (1), betulinic acid (2) and ursolic acid (3) upon purification. Compounds 1–3 were identified using spectroscopic techniques and by comparison with reported data. GLC of unsaponifiable and saponifiable fractions of the hexane extract revealed β-sitosterol (7.37%) and n-tetracosane (54.4%) to be the major sterol and hydrocarbon components, respectively. Linoleic acid (48.89%) was the predominant fatty acid.