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  1. Article: Oxysterols as Biomarkers of Aging and Disease.

    Dias, Irundika H K / Shokr, Hala

    Advances in experimental medicine and biology

    2023  Volume 1440, Page(s) 307–336

    Abstract: Oxysterols derive from either enzymatic or non-enzymatic oxidation of cholesterol. Even though they are produced as intermediates of bile acid synthesis pathway, they are recognised as bioactive compounds in cellular processes. Therefore, their absence ... ...

    Abstract Oxysterols derive from either enzymatic or non-enzymatic oxidation of cholesterol. Even though they are produced as intermediates of bile acid synthesis pathway, they are recognised as bioactive compounds in cellular processes. Therefore, their absence or accumulation have been shown to be associated with disease phenotypes. This chapter discusses the contribution of oxysterol to ageing, age-related diseases such as neurodegeneration and various disorders such as cancer, cardiovascular disease, diabetes, metabolic and ocular disorders. It is clear that oxysterols play a significant role in development and progression of these diseases. As a result, oxysterols are being investigated as suitable markers for disease diagnosis purposes and some drug targets are in development targeting oxysterol pathways. However, further research will be needed to confirm the suitability of these potentials.
    MeSH term(s) Humans ; Oxysterols/metabolism ; Cholesterol/metabolism ; Neoplasms ; Aging ; Biomarkers
    Chemical Substances Oxysterols ; Cholesterol (97C5T2UQ7J) ; Biomarkers
    Language English
    Publishing date 2023-11-30
    Publishing country United States
    Document type Journal Article
    ZDB-ID 410187-X
    ISSN 0065-2598
    ISSN 0065-2598
    DOI 10.1007/978-3-031-43883-7_16
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Effects of carotenoids on mitochondrial dysfunction.

    Ademowo, Opeyemi Stella / Oyebode, Olubukola / Edward, Roshita / Conway, Myra E / Griffiths, Helen R / Dias, Irundika H K

    Biochemical Society transactions

    2024  Volume 52, Issue 1, Page(s) 65–74

    Abstract: Oxidative stress, an imbalance between pro-oxidant and antioxidant status, favouring the pro-oxidant state is a result of increased production of reactive oxygen species (ROS) or inadequate antioxidant protection. ROS are produced through several ... ...

    Abstract Oxidative stress, an imbalance between pro-oxidant and antioxidant status, favouring the pro-oxidant state is a result of increased production of reactive oxygen species (ROS) or inadequate antioxidant protection. ROS are produced through several mechanisms in cells including during mitochondrial oxidative phosphorylation. Increased mitochondrial-derived ROS are associated with mitochondrial dysfunction, an early event in age-related diseases such as Alzheimer's diseases (ADs) and in metabolic disorders including diabetes. AD post-mortem investigations of affected brain regions have shown the accumulation of oxidative damage to macromolecules, and oxidative stress has been considered an important contributor to disease pathology. An increase in oxidative stress, which leads to increased levels of superoxide, hydrogen peroxide and other ROS in a potentially vicious cycle is both causative and a consequence of mitochondrial dysfunction. Mitochondrial dysfunction may be ameliorated by molecules with antioxidant capacities that accumulate in mitochondria such as carotenoids. However, the role of carotenoids in mitigating mitochondrial dysfunction is not fully understood. A better understanding of the role of antioxidants in mitochondrial function is a promising lead towards the development of novel and effective treatment strategies for age-related diseases. This review evaluates and summarises some of the latest developments and insights into the effects of carotenoids on mitochondrial dysfunction with a focus on the antioxidant properties of carotenoids. The mitochondria-protective role of carotenoids may be key in therapeutic strategies and targeting the mitochondria ROS is emerging in drug development for age-related diseases.
    MeSH term(s) Humans ; Antioxidants/metabolism ; Reactive Oxygen Species/metabolism ; Carotenoids/metabolism ; Carotenoids/pharmacology ; Oxidative Stress ; Mitochondrial Diseases/metabolism
    Chemical Substances Antioxidants ; Reactive Oxygen Species ; Carotenoids (36-88-4)
    Language English
    Publishing date 2024-02-19
    Publishing country England
    Document type Review ; Journal Article
    ZDB-ID 184237-7
    ISSN 1470-8752 ; 0300-5127
    ISSN (online) 1470-8752
    ISSN 0300-5127
    DOI 10.1042/BST20230193
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Cholesterol homeostasis in hair follicle keratinocytes is disrupted by impaired ABCA5 activity.

    Palmer, Megan A / Dias, Irundika H K / Smart, Eleanor / Benatzy, Yvonne / Haslam, Iain S

    Biochimica et biophysica acta. Molecular and cell biology of lipids

    2023  Volume 1868, Issue 9, Page(s) 159361

    Abstract: The importance of cholesterol in hair follicle biology is underscored by its links to the pathogenesis of alopecias and hair growth disorders. Reports have associated defects in ABCA5, a membrane transporter, with altered keratinocyte cholesterol ... ...

    Abstract The importance of cholesterol in hair follicle biology is underscored by its links to the pathogenesis of alopecias and hair growth disorders. Reports have associated defects in ABCA5, a membrane transporter, with altered keratinocyte cholesterol distribution in individuals with a form of congenital hypertrichosis, yet the biological basis for this defect in hair growth remains unknown. This study aimed to determine the impact of altered ABCA5 activity on hair follicle keratinocyte behaviour. Primary keratinocytes isolated from the outer root sheath of plucked human hair follicles were utilised as a relevant cell model. Following exogenous cholesterol loading, an increase in ABCA5 co-localisation to intracellular organelles was seen. Knockdown of ABCA5 revealed a dysregulation in cholesterol homeostasis, with LXR agonism leading to partial restoration of the homeostatic response. Filipin staining and live BODIPY cholesterol immunofluorescence microscopy revealed a reduction in endo-lysosomal cholesterol following ABCA5 knockdown. Analysis of oxysterols showed a significant increase in the fold change of 25-hydroxycholesterol and 7-β-hydroxycholesterol following cholesterol loading in ORS keratinocytes, after ABCA5 knockdown. These data suggest a role for ABCA5 in the intracellular compartmentalisation of free cholesterol in primary hair follicle keratinocytes. The loss of normal homeostatic response, following the delivery of excess cholesterol after ABCA5 knockdown, suggests an impact on LXR-mediated transcriptional activity. The loss of ABCA5 in the hair follicle could lead to impaired endo-lysosomal cholesterol transport, impacting pathways known to influence hair growth. This avenue warrants further investigation.
    MeSH term(s) Humans ; Hair Follicle/metabolism ; Keratinocytes/metabolism ; Hypertrichosis/metabolism ; ATP-Binding Cassette Transporters/genetics ; ATP-Binding Cassette Transporters/metabolism ; Homeostasis ; Cholesterol/metabolism
    Chemical Substances ATP-Binding Cassette Transporters ; Cholesterol (97C5T2UQ7J) ; ABCA5 protein, human
    Language English
    Publishing date 2023-06-20
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 60-7
    ISSN 1879-2618 ; 1879-2596 ; 1879-260X ; 1872-8006 ; 1879-2642 ; 1879-2650 ; 0006-3002 ; 0005-2728 ; 0005-2736 ; 0304-4165 ; 0167-4838 ; 1388-1981 ; 0167-4889 ; 0167-4781 ; 0304-419X ; 1570-9639 ; 0925-4439 ; 1874-9399
    ISSN (online) 1879-2618 ; 1879-2596 ; 1879-260X ; 1872-8006 ; 1879-2642 ; 1879-2650
    ISSN 0006-3002 ; 0005-2728 ; 0005-2736 ; 0304-4165 ; 0167-4838 ; 1388-1981 ; 0167-4889 ; 0167-4781 ; 0304-419X ; 1570-9639 ; 0925-4439 ; 1874-9399
    DOI 10.1016/j.bbalip.2023.159361
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Oxysterols and Oxysterol Sulfates in Alzheimer's Disease Brain and Cerebrospinal Fluid.

    Dias, Irundika H K / Shokr, Hala / Shephard, Freya / Chakrabarti, Lisa

    Journal of Alzheimer's disease : JAD

    2022  Volume 87, Issue 4, Page(s) 1527–1536

    Abstract: Background: Brain cholesterol levels are tightly regulated but increasing evidence indicates that cholesterol metabolism may drive Alzheimer's disease (AD)-associated pathological changes. Recent advances in understanding of mitochondrial dysfunction in ...

    Abstract Background: Brain cholesterol levels are tightly regulated but increasing evidence indicates that cholesterol metabolism may drive Alzheimer's disease (AD)-associated pathological changes. Recent advances in understanding of mitochondrial dysfunction in AD brain have presented a vital role played by mitochondria in oxysterol biosynthesis and their involvement in pathophysiology. Oxysterol accumulation in brain is controlled by various enzymatic pathways including sulfation. While research into oxysterol is under the areas of active investigation, there is less evidence for oxysterol sulfate levels in human brain.
    Objective: This study investigates the hypothesis that AD brain oxysterol detoxification via sulfation is impaired in later stages of disease resulting in oxysterol accumulation.
    Methods: Lipids were extracted from postmortem frozen brain tissue and cerebrospinal (CSF) from late- (Braak stage III-IV) and early- (Braak stage I-II) stage AD patients. Samples were spiked with internal standards prior to lipid extraction. Oxysterols were enriched with a two-step solid phase extraction using a polymeric SPE column and further separation was achieved by LC-MS/MS.
    Results: Oxysterols, 26-hydroxycholesterol (26-OHC), 25-hydroxycholesterol (25-OHC), and 7-oxycholesterol levels were higher in brain tissue and mitochondria extracted from late-stage AD brain tissue except for 24S-hydroxycholesterol, which was decreased in late AD. However, oxysterol sulfates are significantly lower in the AD frontal cortex. Oxysterols, 25-OHC, and 7-oxocholesterol was higher is CSF but 26-OHC and oxysterol sulfate levels were not changed.
    Conclusion: Our results show oxysterol metabolism is altered in AD brain mitochondria, favoring synthesis of 26-OHC, 25-OHC, and 7-oxocholesterol, and this may influence brain mitochondrial function and acceleration of the disease.
    MeSH term(s) Alzheimer Disease/pathology ; Brain/pathology ; Chromatography, Liquid ; Humans ; Hydroxycholesterols/metabolism ; Oxysterols/metabolism ; Sulfates/metabolism ; Tandem Mass Spectrometry
    Chemical Substances Hydroxycholesterols ; Oxysterols ; Sulfates
    Language English
    Publishing date 2022-05-18
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1440127-7
    ISSN 1875-8908 ; 1387-2877
    ISSN (online) 1875-8908
    ISSN 1387-2877
    DOI 10.3233/JAD-220083
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Current and Future Directions for Targeting Lipoxin A4 in Alzheimer's Disease.

    Dias, Irundika H K / Griffiths, Helen R

    Journal of Alzheimer's disease : JAD

    2021  Volume 81, Issue 1, Page(s) 87–90

    Abstract: Neuroinflammation has been implicated in Alzheimer's disease onset and progression. Chronic neuroinflammation is initiated by amyloid-β-activated microglial cells that secrete immuno-modulatory molecules within the brain and into the vasculature. ... ...

    Abstract Neuroinflammation has been implicated in Alzheimer's disease onset and progression. Chronic neuroinflammation is initiated by amyloid-β-activated microglial cells that secrete immuno-modulatory molecules within the brain and into the vasculature. Inflammation is normally self-limiting and actively resolves by "switching off" the generation of pro-inflammatory mediators and by non-phlogistic clearance of spent cells and their debris to restore tissue homeostasis. Deficits in these anti-inflammatory/pro-resolution pathways may predispose to the development of chronic inflammation. The synthesis of endogenous lipid mediators from arachidonic acid, lipoxins via cyclooxygenase 2 and lipoxygenases, and conversion of exogenous polyunsaturated fatty acids, namely docosahexaenoic acid and eicosapentaenoic acid, to resolvins contributes to effective, timely resolution of acute inflammation. Work by Xiuzhe et al., 2020 in the Journal of Alzheimer's Disease reported that plasma level of LXA4 is related to cognitive status in ischemic stroke patients suggesting that decreased LXA4 may be a potential risk factor for post post-stroke cognitive impairment. As evident by recent clinical trials and development of drug analogues, there is recent drive to search for lipoxin analogues as therapeutics for inflammatory diseases. Understanding how bioactive lipid signaling is involved in resolution will increase our understanding of controlling inflammation and may facilitate the discovery of new classes of therapeutic pro-resolution agents for evaluation in AD prevention studies.
    MeSH term(s) Alzheimer Disease/metabolism ; Animals ; Brain/metabolism ; Humans ; Inflammation/metabolism ; Inflammation Mediators/metabolism ; Lipoxins/metabolism
    Chemical Substances Inflammation Mediators ; Lipoxins ; lipoxin A4
    Language English
    Publishing date 2021-03-15
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 1440127-7
    ISSN 1875-8908 ; 1387-2877
    ISSN (online) 1875-8908
    ISSN 1387-2877
    DOI 10.3233/JAD-210121
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  6. Article ; Online: Microvascular function and oxidative stress in adult individuals with early onset of cardiovascular disease.

    Shokr, Hala / Dias, Irundika H K / Gherghel, Doina

    Scientific reports

    2020  Volume 10, Issue 1, Page(s) 4881

    Abstract: The current study aims to investigate retinal vascular function and its relationship with systemic anti-oxidative defence capacity in normal individuals versus those with early hypertensive changes according to the current ESC/ESH guidelines. Retinal ... ...

    Abstract The current study aims to investigate retinal vascular function and its relationship with systemic anti-oxidative defence capacity in normal individuals versus those with early hypertensive changes according to the current ESC/ESH guidelines. Retinal microvascular function was assessed in 201 participants by means of dynamic retinal vessel analysis. Blood pressure, lipid panel, oxidized (GSH) & reduced glutathione (GSSG) were also evaluated for each participant. Individuals classed as grade 1 hypertension demonstrated higher retinal arterial baseline diameter fluctuation (p = 0.0012), maximum dilation percentage (p = 0.0007), time to maximum constriction (p = 0.0003) and lower arterial constriction slope (p = 0.0131). Individuals classed as high normal and grade 1 hypertension also demonstrated higher time to maximum dilation than individuals classed as optimal or normal. GSH levels correlated negatively with SBP, DBP and MBP values in all participants (p = 0.0010; p = 0.0350 and p = 0.0050) as well as with MBP values in high normal and grade 1 hypertension (p = 0.0290). The levels of GSSG correlated positively with SBP, DBP and MBP values in all participants (p = 0.0410; p = 0.0330 and, p = 0.0220). Our results point to the fact that microvascular alterations can be identifiable at BP values still considered within normal values and go in parallel with the changes observed in the level of oxidative stress.
    MeSH term(s) Adult ; Biomarkers/metabolism ; Blood Pressure/genetics ; Blood Pressure/physiology ; Cardiovascular Diseases/genetics ; Cardiovascular Diseases/metabolism ; Cardiovascular Diseases/physiopathology ; Female ; Glutathione/metabolism ; Glutathione Disulfide/metabolism ; Humans ; Male ; Middle Aged ; Oxidative Stress/genetics ; Oxidative Stress/physiology ; Retina/metabolism
    Chemical Substances Biomarkers ; Glutathione (GAN16C9B8O) ; Glutathione Disulfide (ULW86O013H)
    Language English
    Publishing date 2020-03-17
    Publishing country England
    Document type Journal Article
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-020-60766-0
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: TNF-α-Mediated Endothelial Cell Apoptosis Is Rescued by Hydrogen Sulfide.

    Diaz Sanchez, Lorena / Sanchez-Aranguren, Lissette / Wang, Keqing / Spickett, Corinne M / Griffiths, Helen R / Dias, Irundika H K

    Antioxidants (Basel, Switzerland)

    2023  Volume 12, Issue 3

    Abstract: Endothelial dysfunction is implicated in the development and aggravation of cardiovascular complications. Among the endothelium-released vasoactive factors, hydrogen sulfide ( ... ...

    Abstract Endothelial dysfunction is implicated in the development and aggravation of cardiovascular complications. Among the endothelium-released vasoactive factors, hydrogen sulfide (H
    Language English
    Publishing date 2023-03-16
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2704216-9
    ISSN 2076-3921
    ISSN 2076-3921
    DOI 10.3390/antiox12030734
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  8. Article ; Online: TNF-α-Mediated Endothelial Cell Apoptosis Is Rescued by Hydrogen Sulfide

    Diaz Sanchez, Lorena / Sanchez-Aranguren, Lissette / Wang, Keqing / Spickett, Corinne M. / Griffiths, H. R. / Dias, Irundika H. K.

    Antioxidants. 2023 Mar. 16, v. 12, no. 3

    2023  

    Abstract: Endothelial dysfunction is implicated in the development and aggravation of cardiovascular complications. Among the endothelium-released vasoactive factors, hydrogen sulfide (H₂S) has been investigated for its beneficial effects on the vasculature ... ...

    Abstract Endothelial dysfunction is implicated in the development and aggravation of cardiovascular complications. Among the endothelium-released vasoactive factors, hydrogen sulfide (H₂S) has been investigated for its beneficial effects on the vasculature through anti-inflammatory and redox-modulating regulatory mechanisms. Reduced H₂S bioavailability is reported in chronic diseases such as cardiovascular disease, diabetes, atherosclerosis and preeclampsia, suggesting the value of investigating mechanisms, by which H₂S acts as a vasoprotective gasotransmitter. We explored whether the protective effects of H₂S were linked to the mitochondrial health of endothelial cells and the mechanisms by which H₂S rescues apoptosis. Here, we demonstrate that endothelial dysfunction induced by TNF-α increased endothelial oxidative stress and induced apoptosis via mitochondrial cytochrome c release and caspase activation over 24 h. TNF-α also affected mitochondrial morphology and altered the mitochondrial network. Post-treatment with the slow-releasing H₂S donor, GYY4137, alleviated oxidising redox state, decreased pro-caspase 3 activity, and prevented endothelial apoptosis caused by TNF-α alone. In addition, exogenous GYY4137 enhanced S-sulfhydration of pro-caspase 3 and improved mitochondrial health in TNF-α exposed cells. These data provide new insights into molecular mechanisms for cytoprotective effects of H₂S via the mitochondrial-driven pathway.
    Keywords apoptosis ; atherosclerosis ; bioavailability ; caspases ; diabetes ; endothelial cells ; hydrogen sulfide ; mitochondria ; oxidative stress ; pre-eclampsia
    Language English
    Dates of publication 2023-0316
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article ; Online
    ZDB-ID 2704216-9
    ISSN 2076-3921
    ISSN 2076-3921
    DOI 10.3390/antiox12030734
    Database NAL-Catalogue (AGRICOLA)

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  9. Article ; Online: Antioxidant Micronutrients and Oxidative Stress Biomarkers.

    Dias, Irundika H K / Griffiths, Helen R / Milward, Mike R / Ling, Martin R / Chapple, Iain L C / Grant, Melissa M

    Methods in molecular biology (Clifton, N.J.)

    2022  Volume 2588, Page(s) 41–58

    Abstract: Chronic inflammatory diseases are the major causes of mortality in humans and recent research has improved our understanding of the major impact of lifestyle factors upon inflammatory diseases and conditions. One of the most influential of these is ... ...

    Abstract Chronic inflammatory diseases are the major causes of mortality in humans and recent research has improved our understanding of the major impact of lifestyle factors upon inflammatory diseases and conditions. One of the most influential of these is nutrition, which may drive both pro-inflammatory as well as anti-inflammatory cascades at molecular and cellular levels. There are a variety of model systems that may be employed to investigate the impact of micronutrients and macronutrients upon inflammatory pathways, many of which operate through oxidative stress, either at the level of controlling the redox state of the cell and downstream redox-regulated gene transcription factors, and other acting as free radical generating or scavenging agents. This chapter focuses upon biological sample preparation prior to assay and details methods for analyzing certain antioxidant micronutrients and biomarkers of oxidative stress.
    MeSH term(s) Humans ; Antioxidants/pharmacology ; Antioxidants/metabolism ; Micronutrients ; Oxidative Stress ; Biomarkers/metabolism ; Oxidation-Reduction
    Chemical Substances Antioxidants ; Micronutrients ; Biomarkers
    Language English
    Publishing date 2022-11-23
    Publishing country United States
    Document type Journal Article
    ISSN 1940-6029
    ISSN (online) 1940-6029
    DOI 10.1007/978-1-0716-2780-8_4
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Chromatography of oxysterols.

    Dias, Irundika H K / Wilson, Steven R / Roberg-Larsen, Hanne

    Biochimie

    2018  Volume 153, Page(s) 3–12

    Abstract: Oxysterols play important roles in development and diseases, but can be highly challenging to analyze. To ensure satisfactory measurements, oxysterols must typically be separated with chromatography prior to detection. Here, we will devote attention to ... ...

    Abstract Oxysterols play important roles in development and diseases, but can be highly challenging to analyze. To ensure satisfactory measurements, oxysterols must typically be separated with chromatography prior to detection. Here, we will devote attention to the chromatography of oxysterols, focusing on gas chromatography and liquid chromatography. We will present the role of stationary phases, mobile phases, and dimensions and geometries of particles/columns. We discuss how these parameters may affect the chromatography, regarding factors such as speed and resolution. Finally, we present some less explored avenues for separation of oxysterols.
    MeSH term(s) Chromatography, Gas/methods ; Chromatography, Liquid/methods ; Oxysterols/isolation & purification
    Chemical Substances Oxysterols
    Language English
    Publishing date 2018-05-09
    Publishing country France
    Document type Journal Article ; Review
    ZDB-ID 120345-9
    ISSN 1638-6183 ; 0300-9084
    ISSN (online) 1638-6183
    ISSN 0300-9084
    DOI 10.1016/j.biochi.2018.05.004
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