19 results on '"Kassouf N"'
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2. The role of plasma membrane STIM1 and Ca2+ entry pathways in platelet aggregation: PB 3.27–2
- Author
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Authi, K S, Ambily, A, Kaiser, J, Pierro, C, Chamberlain, E V, Li, Z, Kassouf, N, Jones, C I, and Gibbins, J M
- Published
- 2013
3. Mitochondrial protein-linked DNA breaks perturb mitochondrial gene transcription and trigger free radical-induced DNA damage
- Author
-
Chiang, S.C., Meagher, M., Kassouf, N., Hafezparast, M., McKinnon, P.J., Haywood, R., and El-Khamisy, S.F.
- Abstract
Breakage of one strand of DNA is the most common form of DNA damage. Most damaged DNA termini require end-processing in preparation for ligation. The importance of this step is highlighted by the association of defects in the 3'-end processing enzyme tyrosyl DNA phosphodiesterase 1 (TDP1) and neurodegeneration and by the cytotoxic induction of protein-linked DNA breaks (PDBs) and oxidized nucleic acid intermediates during chemotherapy and radiotherapy. Although much is known about the repair of PDBs in the nucleus, little is known about this process in the mitochondria. We reveal that TDP1 resolves mitochondrial PDBs (mtPDBs), thereby promoting mitochondrial gene transcription. Overexpression of a toxic form of mitochondrial topoisomerase I (TOP1mt*), which generates excessive mtPDBs, results in a TDP1-dependent compensatory up-regulation of mitochondrial gene transcription. In the absence of TDP1, the imbalance in transcription of mitochondrial- and nuclear-encoded electron transport chain (ETC) subunits results in misassembly of ETC complex III. Bioenergetics profiling further reveals that TDP1 promotes oxidative phosphorylation under both basal and high energy demands. It is known that mitochondrial dysfunction results in free radical leakage and nuclear DNA damage; however, the detection of intermediates of radical damage to DNA is yet to be shown. Consequently, we report an increased accumulation of carbon-centered radicals in cells lacking TDP1, using electron spin resonance spectroscopy. Overexpression of the antioxidant enzyme superoxide dismutase 1 (SOD1) reduces carbon-centered adducts and protects TDP1-deficient cells from oxidative stress. Conversely, overexpression of the amyotrophic lateral sclerosis-associated mutant SOD1(G93A) leads to marked sensitivity. Whereas Tdp1 knockout mice develop normally, overexpression of SOD1(G93A) suggests early embryonic lethality. Together, our data show that TDP1 resolves mtPDBs, thereby regulating mitochondrial gene transcription and oxygen consumption by oxidative phosphorylation, thus conferring cellular protection against reactive oxygen species-induced damage.
- Published
- 2017
4. Cardiorespiratory optimization during improvised singing and toning
- Author
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Bernardi, N. F., primary, Snow, S., additional, Peretz, I., additional, Orozco Perez, H. D., additional, Sabet-Kassouf, N., additional, and Lehmann, A., additional
- Published
- 2017
- Full Text
- View/download PDF
5. The role of plasma membrane STIM1 and Ca2+entry in platelet aggregation. STIM1 binds to novel proteins in human platelets
- Author
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Ambily, A., primary, Kaiser, W.J., additional, Pierro, C., additional, Chamberlain, E.V., additional, Li, Z., additional, Jones, C.I., additional, Kassouf, N., additional, Gibbins, J.M., additional, and Authi, K.S., additional
- Published
- 2014
- Full Text
- View/download PDF
6. Isolation of ORCTL3 in a novel genetic screen for tumor-specific apoptosis inducers
- Author
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Irshad, S, primary, Mahul-Mellier, A-L, additional, Kassouf, N, additional, Lemarie, A, additional, and Grimm, S, additional
- Published
- 2009
- Full Text
- View/download PDF
7. Oral cancer cell lines can use multiple ligands, including Fas-L, TRAIL and TNF-alpha, to induce apoptosis in Jurkat T cells: possible mechanisms for immune escape by head and neck cancers.
- Author
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Kassouf N and Thornhill MH
- Abstract
Some cancer cells can induce apoptosis in tumour infiltrating cytotoxic T cells as a means of escaping immune destruction. This study examined the expression of the apoptosis-inducing ligands, Fas-L, TRAIL and TNF-alpha, on three representative oral squamous cell carcinoma (OSCC) cell lines, TR146, SCC25 and CAL27 and investigates the contribution of these ligands to tumour cell killing of Jurkat T cells in vitro. All three cell lines were able to induce apoptosis in Jurkat T cells to varying degrees. The TR146 cell line predominantly killed Jurkats via the well known Fas-L/Fas mediated pathway. Although TR146 also expressed low levels of TRAIL and TNF-alpha, these did not contribute significantly to TR146 killing of Jurkats. In contrast, the CAL27 cell line expressed little if any Fas-L but was still able to kill Jurkats effectively via an almost exclusively TRAIL mediated mechanism. The SCC25 cell line expressed significant levels of all three ligands but we were unable to significantly inhibit killing of Jurkats by blocking any one pathway with antibodies. SCC25 may use a combination of mechanisms to kill Jurkats and switch between them to compensate when one mechanism is blocked. We found that stimulation with interferon-gamma (IFN-gamma) induced or increased the expression of apoptosis-inducing ligands on OSCC as well as the killing of Jurkat T cells. Not only did IFN-gamma increase killing of Jurkats, but it changed the contribution of the Fas-L, TRAIL and TNF-alpha mediated mechanisms to the killing of Jurkat T cells by the different cell lines. These mechanisms if reproduced in vivo, could confer survival advantage on OSCC by enabling them to kill tumour invading cytotoxic lymphocytes and evade immune destruction. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
8. Phosphatidylinositol-3,4,5-trisphosphate stimulates distinct Ca2+ elevation, Akt phosphorylation and forms a major mechanism of thromboxane A2 formation in human platelets.
- Author
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Authi, K. S., Kassouf, N., Ambily, A., Watson, S., Hassock, S., and Authi, H.
- Subjects
- *
PHOSPHATIDYLINOSITOL 3-kinases , *CHEMICAL reactions , *BLOOD platelets - Abstract
An abstract of the article "Phosphatidylinositol-3,4,5-trisphosphate stimulates distinct Ca2+ elevation, Akt phosphorylation and forms a major mechanism of thromboxane A2 formation in human platelets" by K. S. Authi, N. Kassouf, A. Ambily, S.Watson, S. Hassock, H. Authi and S. Watson is presented.
- Published
- 2014
9. Rapid and green discrimination of bovine milk according to fat content, thermal treatment, brand and manufacturer via colloidal fingerprinting.
- Author
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Giordani S, Kassouf N, Zappi A, Zattoni A, Roda B, Melucci D, and Marassi V
- Subjects
- Animals, Multivariate Analysis, Food Safety, Milk chemistry, Fractionation, Field Flow
- Abstract
Addressing food safety and detecting food fraud while fulfilling greenness requisites for analysis is a challenging but necessary task. The use of sustainable techniques, with limited pretreatment, non-toxic chemicals, high throughput results, is recommended. A combination of Field Flow Fractionation (FFF), working in saline carrier and with minimal preprocessing, and chemometrics was for the first time applied to bovine milk grouping. A set of 47 bovine milk samples was analyzed: a single analysis yielded a characteristic multidimensional colloidal dataset, that once processed with multivariate tools allowed simultaneously for different discriminations: fat content, thermal treatment, brand and manufacturing plant. The analytical methodology is fast, green, simple, and inexpensive and could offer great help in the field of quality control and frauds identification. This work represents also the first attempt to identify milk sub-typologies based on colloidal profiles, and the most complete study concerning multivariate analysis of FFF fingerprint., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Valentina Marassi, Barbara Roda, Andrea Zattoni are associates of the spinoff company byFlow srl. The company mission includes know-how transfer, development, and application of novel technologies and methodologies for the analysis and characterization of samples of nano-biotechnological interest, (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
10. Moderate support for the use of digital tracking to support climate-mitigation strategies.
- Author
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Garard J, Wood SLR, Sabet-Kassouf N, Ventimiglia A, Matthews HD, Ubalijoro É, Chaudhari K, Ivanova M, and Luers AL
- Abstract
The use of digital tracking of individuals throughout the coronavirus 2019 (COVID-19) pandemic renewed societal debates on the efficacy and ethics of digital surveillance to mitigate collective crises. While digital emissions tracking is being used to support climate-mitigation strategies, to date there has been limited exploration of the opportunities and challenges of deploying it at the individual level. Here, we assess temporal and regional differences in levels of support for the use of digital surveillance in times of crisis, such as climate change. Results from a global survey indicate moderate support for the use of digital tracking, including for personal carbon footprints. Response varied regionally, with the lowest support in North America and Europe. This study raises key questions-if digital surveillance tools could be part of a socially acceptable response to the climate crisis, is it worth exploring? Or is this an unacceptable risk for society?, Competing Interests: The authors declare no competing interests. A.L.L. has an additional affiliation with Microsoft Corporation, a technology company, and S.L.R.W. has changed their affiliation to Habitat, an independent consulting company for the implementation of nature-based solutions. Both changes occurred after the study was commissioned, conducted, written, and initially submitted., (© 2022 The Authors. Published by Elsevier Inc.)
- Published
- 2022
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11. A Green Analytical Method Combined with Chemometrics for Traceability of Tomato Sauce Based on Colloidal and Volatile Fingerprinting.
- Author
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Zappi A, Marassi V, Kassouf N, Giordani S, Pasqualucci G, Garbini D, Roda B, Zattoni A, Reschiglian P, and Melucci D
- Subjects
- Chemometrics, Gas Chromatography-Mass Spectrometry methods, Principal Component Analysis, Solanum lycopersicum, Volatile Organic Compounds analysis
- Abstract
Tomato sauce is a world famous food product. Despite standards regulating the production of tomato derivatives, the market suffers frpm fraud such as product adulteration, origin mislabelling and counterfeiting. Methods suitable to discriminate the geographical origin of food samples and identify counterfeits are required. Chemometric approaches offer valuable information: data on tomato sauce is usually obtained through chromatography (HPLC and GC) coupled to mass spectrometry, which requires chemical pretreatment and the use of organic solvents. In this paper, a faster, cheaper, and greener analytical procedure has been developed for the analysis of volatile organic compounds (VOCs) and the colloidal fraction via multivariate statistical analysis. Tomato sauce VOCs were analysed by GC coupled to flame ionisation (GC-FID) and to ion mobility spectrometry (GC-IMS). Instead of using HPLC, the colloidal fraction was analysed by asymmetric flow field-fractionation (AF4), which was applied to this kind of sample for the first time. The GC and AF4 data showed promising perspectives in food-quality control: the AF4 method yielded comparable or better results than GC-IMS and offered complementary information. The ability to work in saline conditions with easy pretreatment and no chemical waste is a significant advantage compared to environmentally heavy techniques. The method presented here should therefore be taken into consideration when designing chemometric approaches which encompass a large number of samples.
- Published
- 2022
- Full Text
- View/download PDF
12. Betulinic Acid-Doxorubicin-Drug Combination Induced Apoptotic Death via ROS Stimulation in a Relapsed AML MOLM-13 Cell Model.
- Author
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Vu M, Kassouf N, and Appiah S
- Abstract
In this study, cell death regulation and induction in AML cell line from a relapsed MLL-rearranged cell model (MOLM-13) was investigated with doxorubin (Dox) and betulinic acid (BetA), singly and in combination. CyQUANT Direct
® and Annexin V/propidium iodide double staining were used to measure the cytotoxic and cell death induction effects of the compounds, respectively. Reactive oxygen species (ROS) generation was measured using 2',7'-dichlorofluorescin diacetate staining. Expressions of proteins and genes were examined by Western blot and reverse transcription polymerase chain reaction analysis, respectively. BetA (20 μM) and Dox (1 μM) indicated a synergistic growth inhibitory effect on MOLM-13 cells. The combined drug caused more cells to reside in irreversible late apoptotic stage compared to the single treatments ( p < 0.05). Elevation in ROS may be the synergistic mechanism involved in MOLM-13 cell death since ROS can directly disrupt mitochondrial activity. In contrast, in leukaemic U-937 cells, the combination treatments attenuated Dox-induced cell death. Dox and the drug combination selectively reduced ( p < 0.05) a recently reported anti-apoptotic Bcl-2 protein isoform p15-20-Bcl-2 in MOLM-13 by our group, without affecting the usually reported p26-Bcl-2-α. Further studies using known inhibitors of apoptosis are required to confirm the potential of Dox-BetA combination to modulate these pathways.- Published
- 2021
- Full Text
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13. Doxorubicin selectively induces apoptosis through the inhibition of a novel isoform of Bcl‑2 in acute myeloid leukaemia MOLM‑13 cells with reduced Beclin 1 expression.
- Author
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Vu M, Kassouf N, Ofili R, Lund T, Bell C, and Appiah S
- Subjects
- Apoptosis drug effects, Autophagy drug effects, Cell Line, Tumor, Doxorubicin therapeutic use, Gene Expression Regulation, Leukemic, Humans, Leukemia, Myeloid, Acute pathology, Protein Isoforms antagonists & inhibitors, Protein Isoforms metabolism, Proto-Oncogene Proteins c-bcl-2 metabolism, Beclin-1 metabolism, Doxorubicin pharmacology, Leukemia, Myeloid, Acute drug therapy, Proto-Oncogene Proteins c-bcl-2 antagonists & inhibitors
- Abstract
The overexpression of anti‑apoptotic Bcl‑2 in acute myeloid leukaemia (AML) may contribute to difficulties in eradicating these cells during chemotherapy. In the present study, doxorubicin (Dox) was evaluated for its potential to induce selective apoptotic cell death in AML MOLM‑13 cells and to modulate autophagy through Bcl‑2 and Beclin 1 protein expression. Annexin V/propidium iodide and 5(6)‑carboxyfluorescein diacetate succinimidyl ester (CFSE) flow cytometric analyses were conducted to determine the effects of Dox on cell death and cell proliferation, respectively, following 48 h of co‑incubation with AML MOLM‑13 or U‑937 monocytic cells. The protein expression levels of Bcl‑2 and Beclin 1 in untreated and treated cells were quantified by western blot analysis. Dox reduced the viability of MOLM‑13 cells partly by inhibiting cell division and inducing cell apoptosis. Dox demonstrated a level of selectivity in its cytotoxicity against MOLM‑13 compared to U‑937 cells (P<0.05). Dox induced a significant decrease in Beclin 1 protein levels in MOLM‑13 cells without significantly affecting the protein levels in U‑937 monocytes. A novel Bcl‑2 15‑20 kDa (p15‑20‑Bcl‑2) isoform was found to be selectively expressed in AML MOLM‑13 cells (but absent in the leukaemic cell lines tested, OCI‑AML2, CML K562 and U‑937). Dox induced a highly significant inhibition of p15‑20‑Bcl‑2 at concentrations of 0.5, 0.75 and 1 µM (P<0.01). However, the usual 26 kDa Bcl‑2 (p26‑Bcl‑2‑α) isoform protein expression was not affected by the drug in either the MOLM‑13 or U‑937 cells. It was thus postulated that Dox exhibited some selectivity by targeting the p15‑20‑Bcl‑2 isoform in MOLM‑13 cells and activating Beclin 1 to induce cell death.
- Published
- 2020
- Full Text
- View/download PDF
14. UVA-induced carbon-centred radicals in lightly pigmented cells detected using ESR spectroscopy.
- Author
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Kassouf N, Kay CWM, Volkov A, Chiang SC, Birch-Machin MA, El-Khamisy SF, and Haywood RM
- Subjects
- Carbon chemistry, Cell Line, Tumor, Cell Nucleus drug effects, Cell Nucleus radiation effects, Cyclic N-Oxides pharmacology, DNA radiation effects, DNA Damage radiation effects, Deoxyguanine Nucleotides chemistry, Electron Spin Resonance Spectroscopy, Humans, Melanocytes radiation effects, Melanoma pathology, Melanoma radiotherapy, Ultraviolet Rays adverse effects, DNA chemistry, Free Radicals chemistry, Melanocytes chemistry, Melanoma chemistry
- Abstract
Ultraviolet-A and melanin are implicated in melanoma, but whether melanin in vivo screens or acts as a UVA photosensitiser is debated. Here, we investigate the effect of UVA-irradiation on non-pigmented, lightly and darkly pigmented melanocytes and melanoma cells using electron spin resonance (ESR) spectroscopy. Using the spin trap 5,5 Dimethyl-1-pyrroline N-oxide (DMPO), carbon adducts were detected in all cells. However, higher levels of carbon adducts were detected in lightly pigmented cells than in non-pigmented or darkly pigmented cells. Nevertheless, when melanin levels were artificially increased in lightly pigmented cells by incubation with L-Tyrosine, the levels of carbon adducts decreased significantly. Carbon adducts were also detected in UVA-irradiated melanin-free cell nuclei, DNA-melanin systems, and the nucleoside 2'-deoxyguanosine combined with melanin, whereas they were only weakly detected in irradiated synthetic melanin and not at all in irradiated 2'-deoxyguanosine. The similarity of these carbon adducts suggests they may be derived from nucleic acid- guanine - radicals. These observations suggest that melanin is not consistently a UVA screen against free-radical formation in pigmented cells, but may also act as a photosensitizer for the formation of nucleic acid radicals in addition to superoxide. The findings are important for our understanding of the mechanism of damage caused by the UVA component of sunlight in non-melanoma and melanoma cells, and hence the causes of skin cancer., (Copyright © 2018 Elsevier Inc. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
15. Exploring the Experience and Effects of Vocal Toning.
- Author
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Snow S, Bernardi NF, Sabet-Kassouf N, Moran D, and Lehmann A
- Subjects
- Adult, Emotions, Female, Humans, Interviews as Topic, Male, Music psychology, Qualitative Research, Surveys and Questionnaires, Music Therapy methods, Relaxation Therapy, Respiration, Singing, Voice
- Abstract
Background: Toning is a form of vocalizing that utilizes the natural voice to express sounds ranging from cries, grunts, and groans to open vowel sounds and humming on the full exhalation of the breath. Music therapists are increasingly utilizing toning in their clinical practice for a variety of therapeutic aims. Yet the effects of toning are not widely understood, with limited research to date., Objective: To gather and analyze descriptive data to better understand the experience and effects of self-administered toning. Primary aims were to: 1) understand participants' experiences with toning, and any effects resulting from their experiences; 2) measure participants' emotional response to toning and singing; and 3) examine similarities and differences across the two datasets., Methods: Participants were 20 adults, ages 20-40 years, who were non-musicians. We conducted semi-structured interviews and used qualitative content analysis to identify major themes and subcategories related to participants' toning experiences. Participants also completed a 48-item questionnaire on music and emotions. Results from the interview and questionnaire data were then compared and contrasted., Results: Results indicate that shifts in attention, awareness, and consciousness frequently occurred when individuals engaged in toning. "Meditative," "calm," and "relaxed" were the three most common descriptors of toning. In contrast, singing evoked stronger emotions and associations than toning, with the three most common descriptors including "nostalgia," "tenderness," and "joyful activation." Findings also suggest that the physical experience with vibrations and the sound of one's own voice may be attributes of toning that likely contribute to its success in inducing altered states of awareness, attention, and consciousness., Conclusions: This study significantly expands our understanding of the experience and effects of toning, and has direct implications for clinical practice, including the identification of effective strategies to successfully engage adults in toning.
- Published
- 2018
- Full Text
- View/download PDF
16. Mitochondrial protein-linked DNA breaks perturb mitochondrial gene transcription and trigger free radical-induced DNA damage.
- Author
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Chiang SC, Meagher M, Kassouf N, Hafezparast M, McKinnon PJ, Haywood R, and El-Khamisy SF
- Subjects
- Animals, DNA, Mitochondrial genetics, Mice, Mice, Knockout, Mitochondrial Proteins genetics, Oxidative Phosphorylation, Oxygen Consumption, Phosphoric Diester Hydrolases genetics, DNA Damage, DNA, Mitochondrial metabolism, Mitochondrial Proteins metabolism, Phosphoric Diester Hydrolases metabolism, Reactive Oxygen Species metabolism, Transcription, Genetic
- Abstract
Breakage of one strand of DNA is the most common form of DNA damage. Most damaged DNA termini require end-processing in preparation for ligation. The importance of this step is highlighted by the association of defects in the 3'-end processing enzyme tyrosyl DNA phosphodiesterase 1 (TDP1) and neurodegeneration and by the cytotoxic induction of protein-linked DNA breaks (PDBs) and oxidized nucleic acid intermediates during chemotherapy and radiotherapy. Although much is known about the repair of PDBs in the nucleus, little is known about this process in the mitochondria. We reveal that TDP1 resolves mitochondrial PDBs (mtPDBs), thereby promoting mitochondrial gene transcription. Overexpression of a toxic form of mitochondrial topoisomerase I (TOP1mt*), which generates excessive mtPDBs, results in a TDP1-dependent compensatory up-regulation of mitochondrial gene transcription. In the absence of TDP1, the imbalance in transcription of mitochondrial- and nuclear-encoded electron transport chain (ETC) subunits results in misassembly of ETC complex III. Bioenergetics profiling further reveals that TDP1 promotes oxidative phosphorylation under both basal and high energy demands. It is known that mitochondrial dysfunction results in free radical leakage and nuclear DNA damage; however, the detection of intermediates of radical damage to DNA is yet to be shown. Consequently, we report an increased accumulation of carbon-centered radicals in cells lacking TDP1, using electron spin resonance spectroscopy. Overexpression of the antioxidant enzyme superoxide dismutase 1 (SOD1) reduces carbon-centered adducts and protects TDP1-deficient cells from oxidative stress. Conversely, overexpression of the amyotrophic lateral sclerosis-associated mutant SOD1
G93A leads to marked sensitivity. Whereas Tdp1 knockout mice develop normally, overexpression of SOD1G93A suggests early embryonic lethality. Together, our data show that TDP1 resolves mtPDBs, thereby regulating mitochondrial gene transcription and oxygen consumption by oxidative phosphorylation, thus conferring cellular protection against reactive oxygen species-induced damage.- Published
- 2017
- Full Text
- View/download PDF
17. Evaluation of absorbent materials for use as ad hoc dry decontaminants during mass casualty incidents as part of the UK's Initial Operational Response (IOR).
- Author
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Kassouf N, Syed S, Larner J, Amlôt R, and Chilcott RP
- Subjects
- Animals, Female, Malonates toxicity, Parathion toxicity, Phorate toxicity, Potassium Cyanide toxicity, Salicylates toxicity, Swine, United Kingdom, Decontamination methods, Mass Casualty Incidents, Skin Absorption drug effects
- Abstract
The UK's Initial Operational Response (IOR) is a revised process for the medical management of mass casualties potentially contaminated with hazardous materials. A critical element of the IOR is the introduction of immediate, on-scene disrobing and decontamination of casualties to limit the adverse health effects of exposure. Ad hoc cleansing of the skin with dry absorbent materials has previously been identified as a potential means of facilitating emergency decontamination. The purpose of this study was to evaluate the in vitro oil and water absorbency of a range of materials commonly found in the domestic and clinical environments and to determine the effectiveness of a small, but representative selection of such materials in skin decontamination, using an established ex vivo model. Five contaminants were used in the study: methyl salicylate, parathion, diethyl malonate, phorate and potassium cyanide. In vitro measurements of water and oil absorbency did not correlate with ex vivo measurements of skin decontamination. When measured ex vivo, dry decontamination was consistently more effective than a standard wet decontamination method ("rinse-wipe-rinse") for removing liquid contaminants. However, dry decontamination was ineffective against particulate contamination. Collectively, these data confirm that absorbent materials such as wound dressings and tissue paper provide an effective, generic capability for emergency removal of liquid contaminants from the skin surface, but that wet decontamination should be used for non-liquid contaminants., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2017
- Full Text
- View/download PDF
18. Phosphatidylinositol-3,4,5-trisphosphate stimulates Ca(2+) elevation and Akt phosphorylation to constitute a major mechanism of thromboxane A2 formation in human platelets.
- Author
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Kassouf N, Ambily A, Watson S, Hassock S, Authi HS, Srivastava S, Watson SP, and Authi KS
- Subjects
- Androstadienes pharmacology, Blood Platelets cytology, Blood Platelets metabolism, Egtazic Acid pharmacology, Enzyme-Linked Immunosorbent Assay, Fura-2 chemistry, Humans, Intracellular Signaling Peptides and Proteins metabolism, Phospholipase C gamma antagonists & inhibitors, Phospholipase C gamma metabolism, Phosphorylation drug effects, Platelet Aggregation drug effects, Protein Kinase Inhibitors pharmacology, Protein-Tyrosine Kinases metabolism, Proto-Oncogene Proteins c-akt antagonists & inhibitors, Syk Kinase, Thromboxane A2 analysis, Wortmannin, Blood Platelets drug effects, Calcium metabolism, Phosphatidylinositol Phosphates pharmacology, Proto-Oncogene Proteins c-akt metabolism, Thromboxane A2 metabolism
- Abstract
Phosphatidylinositol trisphosphate (PIP3) has been implicated in many platelet functions however many of the mechanisms need clarification. We have used cell permeable analogues of PIP3,1-O-(1,2-di-palmitoyl-sn-glyero-3-O-phosphoryl)-D-myo-inositol-3,4,5-trisphosphate (DiC16-PIP3) or 1-O-(1,2-di-octanoyl-sn-glyero-3-O-phosphoryl)-D-myo-inositol-3,4,5-trisphosphate (DiC8-PIP3) to study their effects on activation on washed human platelets. Addition of either DiC8- or DiC16-PIP3 to human platelets induced aggregation in the presence of extracellular Ca(2+). This was reduced by the presence of indomethacin, the phospholipase C inhibitor U73122 and apyrase. DiC8-PIP3 induced the phosphorylation of Akt-Ser(473) which was reduced by the Akt inhibitor IV, wortmannin and EGTA (suggesting a dependence on Ca(2+) entry). In Fura2 loaded platelets DiC8-PIP3 was effective at increasing intracellular Ca(2+) in a distinct and transient manner that was reduced in the presence of indomethacin, U73122 and 2-aminoethyl diphenylborinate (2APB). Ca(2+) elevation was reduced by the non-SOCE inhibitor LOE908 and also by the SOCE inhibitor BTP2. DiC8-PIP3 induced the release of Ca(2+) from stores which was not affected by the proton dissipating agent bafilomycin A1 and was more potent than the two-pore channel agonist DiC8-PI[3,5]P2 suggesting release from an endoplasmic reticulum type store. DiC8-PIP3 weakly induced the tyrosine phosphorylation of Syk but not of PLCγ2. Finally like thrombin DiC8-PIP3 induced the formation of thromboxane B2 that was inhibited by the Akt inhibitor IV. These studies suggest that PIP3 via Ca(2+) elevation and Akt phosphorylation forms a central role in thromboxane A2 formation and the amplification of platelet activation., (Copyright © 2015 Elsevier Inc. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
19. Intensity-dependent direct solar radiation- and UVA-induced radical damage to human skin and DNA, lipids and proteins.
- Author
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Haywood R, Andrady C, Kassouf N, and Sheppard N
- Subjects
- Humans, Proteins metabolism, Skin metabolism, Lipid Metabolism radiation effects, Proteins radiation effects, Skin radiation effects, Sunlight
- Abstract
Skin can be exposed to high-intensity UV-radiation in hot countries and during sunbed use; however, the free-radical damage at these intensities is unknown. We used electron spin resonance spectroscopy to measure free-radical generation in ex vivo human skin/substitutes +/- the spin-trap 5,5 dimethyl-1-pyrroline N-oxide (DMPO) exposed to solar-irradiation equivalent to Mediterranean sunlight. Skin-substitutes, model DNA-photosensitizer systems, lipids and proteins were also irradiated with low-intensity UVA/visible light. Without DMPO a broad singlet was detected (using both irradiations) in skin/substitutes, nail-keratin, tendon-collagen, phospholipid and DNA+melanin or riboflavin. In addition to lipid-derived (tentatively tert-alkoxyl/acyl-) and protein radicals detected with DMPO at lower intensities, isotropic carbon-, additional oxygen- and hydrogen-adducts were detected in solar-irradiated skin/substitutes at higher intensities. Carbon-adducts were detected in UVA-irradiated human skin cells, DNA+melanin or riboflavin and soybean-phospholipid. Anisotropic protein-adducts, comparable to adducts in solar-irradiated tendon-collagen, were absent in UVA-irradiated skin fibroblasts suggesting the trapping of extracellular collagen radicals. Absence of hydrogen-adducts in fibroblasts implies formation in the extracellular compartment. We conclude damage at high intensities is part cellular (carbon- and oxygen-radicals) and part extracellular (protein- and hydrogen/H(+)+e(-) ), and skin substitutes are suitable for sunscreen testing. While UVA absorption and lipid-oxidation is direct, DNA and protein-oxidation require photosensitisation., (© 2010 The Authors. Photochemistry and Photobiology © 2010 The American Society of Photobiology.)
- Published
- 2011
- Full Text
- View/download PDF
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