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12
result(s) for
"Amar, Yacine"
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Pre-digest of unprotected DNA by Benzonase improves the representation of living skin bacteria and efficiently depletes host DNA
by
Lagkouvardos, Ilias
,
Niedermeier, Sebastian
,
Köberle, Martin
in
16S rRNA
,
Acne
,
Antimicrobial peptides
2021
Background
The identification of microbiota based on next-generation sequencing (NGS) of extracted DNA has drastically improved our understanding of the role of microbial communities in health and disease. However, DNA-based microbiome analysis cannot
per se
differentiate between living and dead microorganisms. In environments such as the skin, host defense mechanisms including antimicrobial peptides and low cutaneous pH result in a high microbial turnover, likely resulting in high numbers of dead cells present and releasing substantial amounts of microbial DNA. NGS analyses may thus lead to inaccurate estimations of microbiome structures and consequently functional capacities.
Results
We investigated in this study the feasibility of a Benzonase-based approach (BDA) to pre-digest unprotected DNA, i.e., of dead microbial cells, as a method to overcome these limitations, thus offering a more accurate assessment of the living microbiome. A skin mock community as well as skin microbiome samples were analyzed using 16S rRNA gene sequencing and metagenomics sequencing after DNA extraction with and without a Benzonase digest to assess bacterial diversity patterns. The BDA method resulted in less reads from dead bacteria both in the skin mock community and skin swabs spiked with either heat-inactivated bacteria or bacterial-free DNA. This approach also efficiently depleted host DNA reads in samples with high human-to-microbial DNA ratios, with no obvious impact on the microbiome profile. We further observed that low biomass samples generate an α-diversity bias when the bacterial load is lower than 10
5
CFU and that Benzonase digest is not sufficient to overcome this bias.
Conclusions
The BDA approach enables both a better assessment of the living microbiota and depletion of host DNA reads.
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Video abstract
Graphical abstract
Journal Article
Darier’s disease exhibits a unique cutaneous microbial dysbiosis associated with inflammation and body malodour
by
Eyerich, Stefanie
,
Lagkouvardos, Ilias
,
Rogner, Danielle
in
ATP2A2 gene
,
Bioinformatics
,
Biomedical and Life Sciences
2023
Background
Darier’s disease (DD) is a genodermatosis caused by mutations of the
ATP2A2
gene leading to disrupted keratinocyte adhesion. Recurrent episodes of skin inflammation and infections with a typical malodour in DD indicate a role for microbial dysbiosis. Here, for the first time, we investigated the DD skin microbiome using a metabarcoding approach of 115 skin swabs from 14 patients and 14 healthy volunteers. Furthermore, we analyzed its changes in the context of DD malodour and the cutaneous DD transcriptome.
Results
We identified a disease-specific cutaneous microbiome with a loss of microbial diversity and of potentially beneficial commensals. Expansion of inflammation-associated microbes such as
Staphylococcus aureus
and
Staphylococcus warneri
strongly correlated with disease severity. DD dysbiosis was further characterized by abundant species belonging to
Corynebacteria
,
Staphylococci
and
Streptococci
groups displaying strong associations with malodour intensity. Transcriptome analyses showed marked upregulation of epidermal repair, inflammatory and immune defence pathways reflecting epithelial and immune response mechanisms to DD dysbiotic microbiome. In contrast, barrier genes including claudin-4 and cadherin-4 were downregulated.
Conclusions
These findings allow a better understanding of Darier exacerbations, highlighting the role of cutaneous dysbiosis in DD inflammation and associated malodour. Our data also suggest potential biomarkers and targets of intervention for DD.
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Video Abstract
Journal Article
Munich atopy prediction study (MAPS): protocol for a prospective birth cohort addressing clinical and molecular risk factors for atopic dermatitis in early childhood
2022
IntroductionThe pathogenesis of atopic diseases is highly complex, and the exact mechanisms leading to atopic dermatitis (AD) onset in infants remain mostly enigmatic. In addition to an interdependent network of components of skin development in young age and skin barrier dysfunction underlying AD development that is only partially understood, a complex interplay between environmental factors and lifestyle habits with skin barrier and immune dysregulation is suspected to contribute to AD onset. This study aims to comprehensively evaluate individual microbiome and immune responses in the context of environmental determinants related the risk of developing AD in the first 4 years of a child’s life.Methods and analysesThe ‘Munich Atopic Prediction Study’ is a comprehensive clinical and biological investigation of a prospective birth cohort from Munich, Germany. Information on pregnancy, child development, environmental factors, parental exposures to potential allergens and acute or chronic diseases of children and parents are collected by questionnaires together with a meticulous clinical examination by trained dermatologists focusing on allergies, skin health, and in particular signs of AD at 2 months after birth and then every 6 months. In addition, skin barrier functions are assessed through cutometry, corneometry and transepidermal water loss at every visit. These measurements are completed with allergy diagnostics and extensive microbiome analyses from stool and skin swabs as well as transcriptome analyses using skin microbiopsies.The aim is to assess the relevance of different known and yet unknown risk factors of AD onset and exacerbations in infants and to identify possible accessible and robust biomarkers.Ethics and disseminationThe study is approved by the Ethical Committee of the Medical Faculty of the Technical University of Munich (reference 334/16S). All relevant study results will be presented at national and international conferences and in peer-reviewed journals.
Journal Article
Baricitinib Augments Lonafarnib Therapy to Preserve Colonic Homeostasis and Microbial Balance in a Mouse Model of Progeria
by
Djabali, Karima
,
Schroll, Moritz
,
Krüger, Peter
in
Animal models
,
Animals
,
Azetidines - pharmacology
2025
Hutchinson‐Gilford Progeria Syndrome (HGPS) is a fatal genetic disorder caused by progerin, a mutant lamin A variant that disrupts nuclear architecture and drives systemic cellular dysfunction. Gastrointestinal (GI) involvement in HGPS remains poorly understood, despite growing evidence of gut abnormalities and microbial dysbiosis in progeroid mouse models. Here, we provide the first comprehensive characterization of colonic pathology in LmnaG609G/G609G mice and assess the therapeutic impact of baricitinib (Bar), a JAK–STAT inhibitor, lonafarnib (FTI), the only FDA‐approved therapy, and their combination on colonic health. Bar + FTI combination therapy most effectively lowered progerin levels, preserved colonic architecture and epithelial regeneration markers, while also reducing inflammation, cellular senescence, and early fibrotic changes. Notably, FTI monotherapy aggravated inflammation via STAT1 activation, an effect reversed by Bar co‐administration. Bar also emerged as the primary driver in mitigating colonic tissue senescence, highlighting its role in supporting intestinal homeostasis. In addition, we observed marked microbial dysbiosis in HGPS mice, particularly in late‐stage disease. While both monotherapies induced distinct shifts in gut microbiota, combination therapy preserved a profile more closely resembling healthy controls. These findings expand the current understanding of GI involvement in HGPS and identify the colon as a site where JAK–STAT inhibition enhances the therapeutic profile of FTI. Combined baricitinib and lonafarnib treatment improved colonic pathology in LmnaG609G/G609G progeria mice by reducing progerin, maintaining epithelial regeneration, mitigating inflammation and senescence, and preserving microbiome composition.
Journal Article
Flavonoid profile, antioxidant and cytotoxic activity of different extracts from Algerian Rhamnus alaternus L. bark
by
Harzallah, Daoud
,
Donato, Paola
,
Cacciola, Francesco
in
Antioxidants (Nutrients)
,
Flavonoids
,
Health aspects
2015
Rhamnus alaternus (Rhamnaceae) L. has been traditionally used for treatment of many diseases.
In this study, we determined the antioxidant/free radical scavenger properties, the flavonoid profile and the cytotoxicity of aqueous and methanolic extracts obtained by maceration from Algerian R. alaternus bark, like also of aqueous extract prepared by decoction according to the traditional method. This to estimate the usefulness of the drug traditional preparation and compare it with those made in the laboratory.
The antioxidant activity of the extracts was evaluated using five different redox-based assays, all involving one redox reaction with the oxidant. High-performance liquid chromatography/diode array detection/electrospray ionization mass spectrometry analysis was used to identify and quantify the flavonoids content. Cytotoxicity on human monocytic leukemia cells (U937) was also carried out.
All the extracts tested showed a good antioxidant/free radical scavenger activity and a similar flavonoid fingerprint. However, the methanolic one presented the best antioxidant activity that can be due to the highest flavonoid amount and significantly reduced the proliferation of leukemia cells. The results confirm that the extract prepared by decoction contains efficient antioxidant compounds and this justifies in part the therapeutic and preventive usefulness. Moreover, the methanolic extract exerted excellent cytotoxicity on U937 that could be attributed to kaempferol and rhamnocitrin glycosides.
Journal Article
Light-triggered defect dynamics in silicon wafers: understanding degradation mechanisms
2024
In this work, the effect of heat treatment on the minority carrier lifetime (τ) in boron-doped crystalline silicon wafers coated with a silicon nitride (SiNx:H) layer has been investigated. The results showed an initial increase in τ during the early phase of light exposure of the samples, which was attributed to the presence of iron–boron complexes in the c-Si wafers. However, this enhancement was followed by a decrease associated with the formation of boron-oxygen complexes, known as light-induced degradation. Moreover, kinetic models were used to analyze defect interactions in the wafers, showing a correlation between τ behavior and hydrogen-boron complex concentrations, and related by analytical techniques. In addition, the samples were subjected to a dark annealing step, resulting in further degradation due to the firing temperature process and the presence of hydrogen atoms in the silicon nitride layer. Finally, this study provides valuable insights into defect formation mechanisms in c-Si wafers that could improve the stability and efficiency optimization of silicon-based solar cells under operating conditions.
Journal Article
Experimental Investigation on Two Novel Standard Parameters to Improve The Performance of Solar Box Cookers
2024
The size and shape of solar box cooker is determined by the volume of the vessel, which in turn depends on the number of family members. The primary objective of this study is to overcome the obstacles inhibiting researchers from crafting solar box cookers tailored to their specific research needs, as well as hindrances preventing manufacturers from effectively bringing them to market. This experimental study aims to identify two novel optimal volumetric efficiencies (VE
and VE
) to minimize cooking time. To achieve this goal, we employed two identical solar box cookers made from the same materials and four vessels. The results obtained clearly show that the absorber temperature reached a maximum value of 124.9 °C and the boiling time was the shortest 02h50 when the first volumetric efficiency VE
had the least value of 6.2% and the second volumetric efficiency VE
had the greatest value of 100%. It is concluded that these two volumetric efficiencies could serve as benchmark parameters for future research, providing a standardized reference for developing solar box cookers of varied shapes and sizes under the same climatic conditions.
Journal Article
Intravenous Oxycodone Versus Other Intravenous Strong Opioids for Acute Postoperative Pain Control: A Systematic Review of Randomized Controlled Trials
by
Belbachir, Anissa
,
Kok Yuen Ho
,
Salti, Amar
in
Analgesics
,
Clinical trials
,
Evidence-based medicine
2019
IntroductionOptimal pain management is crucial to the postoperative recovery process. We aimed to evaluate the efficacy and safety of intravenous oxycodone with intravenous fentanyl, morphine, sufentanil, pethidine, and hydromorphone for acute postoperative pain.MethodsA systematic literature search of PubMed, Cochrane Library, and EMBASE databases was performed for randomized controlled trials published from 2008 through 2017 (inclusive) that evaluated the acute postoperative analgesic efficacy of intravenous oxycodone against fentanyl, morphine, sufentanil, pethidine, and hydromorphone in adult patients (age ≥ 18 years). Outcomes examined included analgesic consumption, pain intensity levels, side effects, and patient satisfaction.ResultsEleven studies were included in the review; six compared oxycodone with fentanyl, two compared oxycodone with morphine, and three compared oxycodone with sufentanil. There were no eligible studies comparing oxycodone with pethidine or hydromorphone. Overall, analgesic consumption was lower with oxycodone than with fentanyl or sufentanil. Oxycodone exhibited better analgesic efficacy than fentanyl and sufentanil, and comparable analgesic efficacy to morphine. In terms of safety, there was a tendency towards more side effects with oxycodone than with fentanyl, but the incidence of side effects with oxycodone was comparable to morphine and sufentanil. Where patient satisfaction was evaluated, higher satisfaction levels were observed with oxycodone than with sufentanil and comparable satisfaction was noted when comparing oxycodone with fentanyl. Patient satisfaction was not evaluated in the studies comparing oxycodone with morphine.ConclusionsOur findings suggest that intravenous oxycodone provides better analgesic efficacy than fentanyl and sufentanil, and comparable efficacy to morphine with less adverse events such as sedation. No studies comparing intravenous oxycodone with pethidine or hydromorphone were identified in this review. Better alignment of study methodologies for future research in this area is recommended to provide the best evidence base for a meta-analysis.FundingMundipharma Singapore Holding Pte Ltd, Singapore.
Journal Article