Publications by authors named "Roland Jourdain"
Article Synopsis
- The skin acts as a protective layer for the body and plays a crucial role in how we interact with our environment, with a strong interest in understanding its function and aging effects.
- A study was conducted comparing touch perception between younger (20-28 years) and older women (65-75 years), looking into aspects like touch detection, skin hydration, and the effects of moisturizing cream.
- Results showed that older adults experienced drier skin and reduced touch ability on their fingers, but touching appreciation increased with age, highlighting the importance of long-term skin care for maintaining touch perception, especially on the hands.
Article Synopsis
- Dandruff is a persistent scalp condition that can be influenced by various environmental and personal factors, leading to changes in scalp health that may require treatment like Selenium disulfide (SeS2) shampoo.
- Research focused on how SeS2 shampoo affects dandruff severity, scalp microbiome, and sebum properties during treatment and after resuming normal conditions.
- The study found that SeS2 significantly reduced dandruff symptoms and harmful microbes in the scalp, improved the balance of beneficial bacteria, and enhanced the quality of scalp oils, showing good tolerance from users even after stopping treatment.
Article Synopsis
- Dandruff is a common scalp issue caused by various microbial and host-related factors, with Malassezia restricta yeast playing a significant role in its development.
- Recent studies identified squalene monohydroperoxide and malondialdehyde as biomarkers related to dandruff, indicating that sebum lipoperoxidation is important in dandruff's onset and persistence.
- The research suggests that Malassezia restricta contributes to sebum peroxidation, leading to skin barrier changes, and proposes that inhibiting these processes might offer a new way to treat dandruff.
Article Synopsis
- Dandruff is a widespread issue related to scalp and skin conditions, and scalp seborrheic dermatitis (SD) represents a more severe form with intense itching and inflammation.
- Histamine is a notable biomarker found in scalps affected by dandruff and SD, although the exact mechanism behind its role is still unclear.
- A study in India utilized advanced testing methods to measure histamine levels in non-invasive scalp samples, finding that those with dandruff or mild to moderate SD had significantly elevated histamine levels compared to healthy scalps.
Article Synopsis
- Recent studies indicate that amyloidogenic proteins may deposit in non-neuronal tissues, including skin, in diseases like Alzheimer's and Parkinson's, though detection in skin has been contentious.
- Using techniques like immunohistochemistry and mass spectrometry, researchers found neurodegenerative proteins such as α-synuclein, tau, and Aβ34 in the epidermal layer of human skin samples.
- The presence of α-synuclein was a novel finding in skin cells' nuclei, and the study suggests further investigation could uncover age-related changes in protein expressions, which could aid in diagnosis.
Article Synopsis
- Malassezia restricta is a type of yeast commonly found on human skin and is linked to scalp disorders.
- The complete genome sequence of the Malassezia restricta CBS 7877 strain has been reported.
- This genome sequence will help researchers understand how this yeast interacts with skin and its potential roles in both health (commensal) and disease (pathogenic).
Article Synopsis
- * This research utilized a semi-culture independent method to investigate phage communities on the skin of South African participants, resulting in the addition of over 130 new phage species to existing databases.
- * The findings revealed that some identical phages were found across different individuals and body sites, with a specific bacteriophage linked to Staphylococcus capitis potentially acting as a common virus regulating skin health.
The endocannabinoid system comprises cannabinoid receptors 1 and 2 (CB and CB), their endogenous ligands, anandamide (AEA) and 2-arachidonoylglycerol, and metabolic enzymes of these ligands. The endocannabinoid system has recently been implicated in the regulation of various pathophysiological processes of the skin that include immune competence and/or tolerance of keratinocytes, the disruption of which might promote the development of skin diseases. Recent evidence showed that CB in keratinocytes limits the secretion of proinflammatory chemokines, suggesting that this receptor might also regulate T cell dependent inflammatory diseases of the skin.
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- The study focused on identifying proteins in the top layer of the skin from dandruff and non-dandruff scalps, using a method called iTRAQ-based quantitative proteomic analysis, which found 68 proteins that are expressed differently.
- Key findings showed significant changes in proteins related to skin structure, moisture regulation, and an imbalance in enzymes that affect skin health in dandruff scalps.
- Interestingly, about 50% of the proteins that were altered in dandruff were also found to be similar to those in atopic dermatitis, suggesting possible shared mechanisms in these skin conditions.
Article Synopsis
- The study examined skin microbiota in men from six ethnic groups at three body sites (forearm, axilla, scalp) in NYC.
- Samples were collected before and after a four-day period of using neutral soap while halting regular personal hygiene products, with DNA analysis conducted through advanced sequencing techniques.
- Results indicated that skin location significantly influences bacterial community composition, with greater species diversity on the forearm, and variations in diversity among ethnic groups due to changes in hygiene practices.
Article Synopsis
- - Dandruff is influenced by three main factors: personal susceptibility, scalp oil (sebum), and Malassezia yeast, with a study focusing on the role of sebum in dandruff development.
- - An analysis showed that squalene, a key component of scalp oil, is significantly more oxidized in individuals with dandruff, indicating higher levels of oxidative stress compared to those without dandruff.
- - The study suggests that the increased levels of oxidized squalene (SQOOH) might contribute to dandruff by compromising scalp barrier function and possibly serving as an inflammatory factor, with Malassezia being a possible contributor to this process.
Article Synopsis
- Dandruff is a scalp condition marked by flaky white-yellowish scales, resulting from issues like disrupted skin barrier, decreased hydration, and ongoing inflammation.
- A recent study found that an imbalance in bacterial and fungal populations on the scalp of French volunteers was linked to dandruff, prompting a similar investigation on Chinese volunteers.
- The results showed that both populations had a higher presence of Malassezia restricta and specific bacterial strains in dandruff cases, suggesting similar underlying causes, with the potential for targeted antifungal treatment to improve condition across different regions.
Article Synopsis
- Malassezia spp. are yeasts associated with skin diseases, and this study examined how human skin cells (keratinocytes) respond to different strains, specifically M. globosa and M. restricta.
- The research found that these strains trigger different inflammatory and immune responses, influenced by the TLR2 receptor, with M. globosa and restricta showing significant cytotoxic effects on keratinocytes compared to M. furfur.
- The findings suggest that M. globosa and M. restricta may work together to worsen certain skin conditions due to their unique interactions with skin cells.
Article Synopsis
- * The study focuses on Malassezia restricta, a key yeast of healthy skin, revealing that its cell wall is mainly composed of alkali-insoluble polysaccharides, which contribute to its structure and rigidity.
- * The analysis shows M. restricta's unique cell wall composition, consisting of about 70% β-(1,6)-glucan, alongside significant amounts of chitin and chitosan, differing from other fungal species studied so far.
The bacterial and fungal communities associated with dandruff were investigated using culture-independent methodologies in the French subjects. The major bacterial and fungal species inhabiting the scalp subject's were identified by cloning and sequencing of the conserved ribosomal unit regions (16S for bacterial and 28S-ITS for fungal) and were further quantified by quantitative PCR. The two main bacterial species found on the scalp surface were Propionibacterium acnes and Staphylococcus epidermidis, while Malassezia restricta was the main fungal inhabitant.
View Article and Find Full Text PDFWe show that a fully functional endocannabinoid system is present in primary human melanocytes (normal human epidermal melanocyte cells), including anandamide (AEA), 2-arachidonoylglycerol, the respective target receptors (CB(1), CB(2), and TRPV1), and their metabolic enzymes. We also show that at higher concentrations AEA induces normal human epidermal melanocyte apoptosis (∼3-fold over controls at 5 μM) through a TRPV1-mediated pathway that increases DNA fragmentation and p53 expression. However, at lower concentrations, AEA and other CB(1)-binding endocannabinoids dose-dependently stimulate melanin synthesis and enhance tyrosinase gene expression and activity (∼3- and ∼2-fold over controls at 1 μM).
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- - The study investigates how different ethnicities (Asian, African, and Caucasian) experience sensitivity to capsaicin, a compound found in chili peppers that can cause a burning sensation.
- - Conducted on 144 women, the research involved applying varying concentrations of capsaicin to one side of their faces to measure their detection thresholds, revealing minor differences in sensitivity among the ethnic groups.
- - Overall, results indicated that Asian women had higher sensitivity to capsaicin than Caucasians but lower sensitivity than Africans, with the differences being relatively minor across all groups.
Article Synopsis
- About 50% of women consider their skin sensitive, but this perception lacks a clear physiological basis, prompting researchers to explore the neural response to skin irritants through fMRI.
- Participants were categorized based on their self-reported skin sensitivity and underwent fMRI scans while experiencing discomfort from lactic acid applications to measure brain activation.
- Results showed that those with sensitive skin exhibited greater brain activation in specific areas, suggesting a distinct neurophysiological pattern linked to their perception of skin sensitivity.
Article Synopsis
- Atopic dermatitis (AD) is a long-lasting skin condition characterized by inflammation and requires regular use of moisturizers to help restore skin health.
- A study tested a 5% extract of the bacterium Vitreoscilla filiformis (V.f.) in an ointment, assessing its effectiveness and safety in treating mild to moderate AD over a month.
- Results showed that patients using the V.f. ointment experienced significant improvements in their skin symptoms after just two weeks, indicating this extract could enhance existing AD treatments.
Article Synopsis
- This study evaluated a new test measuring skin sensitivity using capsaicin on 150 healthy adult women to establish detection thresholds.
- Subjects applied various capsaicin concentrations on their skin and reported sensations, enabling classification into different sensitivity levels.
- Results indicated two distinct groups: those with low and high sensitivity, with lower thresholds aligning with self-reported sensitive skin, suggesting the test's potential for cosmetic applications.