The Lab – Aesthetics Science & Insights – Page 8 – Creative Touch

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Senescence-associated secretory phenotype
MedicalCondition
The pro‑inflammatory secretory programme of senescent cells, releasing cytokines and MMPs that degrade collagen, suppress regeneration, and drive chronic tissue inflammation.
Serine
ChemicalSubstance
Serine is a key amino acid for skin, required for ceramide synthesis via serine palmitoyltransferase and as a major NMF component that supports hydration and keratinocyte proliferation.
Serine palmitoyltransferase
Protein
The rate-limiting enzyme initiating de novo ceramide synthesis from serine and palmitoyl-CoA. SPT activity is directly suppressed by declining oestrogen and cortisol elevation.
Sex hormone binding globulin
Protein
Liver-produced glycoprotein that binds testosterone, DHT, and oestradiol with high affinity, functioning as the primary gatekeeper of sex hormone bioavailability.
Short-chain fatty acid
ChemicalSubstance
Short-chain fatty acids are microbially-derived metabolites - principally butyrate, propionate, and acetate - that serve as the primary functional output of a healthy gut microbiome.
Sirtuin
Protein
NAD⁺-dependent deacetylase enzymes found in every skin cell. SIRT1 is the most skin-relevant family member, regulating circadian clock amplitude, suppressing NF-κB-driven inflammation.
Skin
AnatomicalStructure
The body's largest organ, comprising epidermis, dermis, and subcutaneous tissue. Barrier function, structural integrity, and cellular renewal all decline through distinct but interacting mechanisms.
Skin ageing
BiologicalProcess
Skin ageing is the gradual decline of dermal structure, epidermal renewal, and barrier function, driven by intrinsic ageing and accelerated by environmental stressors.
Skin barrier dysfunction
MedicalCondition
Barrier dysfunction describes the full spectrum of stratum corneum failure, from the earliest detectable impairment of moisture retention to the self-perpetuating inflammatory cycle.
Skin Boosters
MedicalTherapy
Injectable hyaluronic‑acid formulations, sometimes with complementary actives, placed into the dermis to restore hydration, stimulate fibroblast activity and improve skin quality.
Skin circadian clock
BiologicalProcess
The circadian rhythm of the skin barrier describes the 24-hour molecular programme by which skin cells time their protective, regenerative, and repair functions.
Skin dysbiosis
MedicalCondition
A state of microbial community imbalance on the skin surface, characterised by loss of commensal species, reduced diversity, and conditions that permit pathogenic overgrowth.
Skin microbiome
BioChemEntity
The community of microbes on the skin that shapes barrier function by regulating pH, aiding ceramide production, tuning innate immunity, and preventing pathogen overgrowth.
Sodium lauryl sulfate
ChemicalSubstance
An anionic surfactant used in cleansers, shampoos, and personal care products that disrupts the stratum corneum through two sequential mechanisms.
Solar elastosis
MedicalCondition
The accumulation of disorganised, non-functional elastotic material in the upper dermis, representing the defining histological marker of photoaged skin.
Squalane
MolecularEntity
The fully hydrogenated, saturated derivative of squalene. Retains squalene's emollient properties and skin compatibility whilst offering oxidative stability.
Squalene
MolecularEntity
A triterpene lipid produced endogenously in the liver and sebaceous glands, and a significant component of human sebum. Functions as a surface antioxidant and emollient.
Staphylococcus aureus
BioChemEntity
A gram-positive, facultatively commensal bacterium that becomes the dominant skin pathogen in dysbiotic conditions.
Staphylococcus epidermidis
BioChemEntity
The dominant commensal bacterium on human skin, once regarded primarily as an opportunistic pathogen but now understood as an active contributor to barrier integrity and antimicrobial defence.
Stearic acid
MolecularEntity
An 18-carbon saturated fatty acid found in tallow, beef, and cocoa butter, and a significant component of human sebum.
Stratum basale
AnatomicalStructure
The deepest viable epidermal layer, anchored to the dermis via the basement membrane zone, housing the keratinocyte stem cell population that feeds the entire differentiation programme above it.
Stratum corneum
AnatomicalStructure
The outermost layer of the epidermis, composed of 15–20 layers of anucleate corneocytes embedded in a structured lipid matrix. Functions as the primary permeability barrier.
Stratum granulosum
AnatomicalStructure
The stratum granulosum is the granular layer of the viable epidermis immediately beneath the stratum corneum, where keratinocytes complete terminal differentiation.
Stratum spinosum
AnatomicalStructure
The stratum spinosum is the epidermal layer where strong desmosomal junctions form, keratinocytes begin differentiation, and Langerhans cells survey for antigens.
Subcutaneous tissue
AnatomicalStructure
Metabolically active deepest skin layer whose ageing drives inflammageing through adipocyte senescence. Target of cryolipolysis, cavitation, HIEMT, RF, and injection lipolysis.
Substance P
ChemicalSubstance
Substance P is an 11‑amino‑acid neuropeptide that drives neurogenic inflammation, itch, pain, mast‑cell activation, and stress‑linked hair shedding via NK1 receptor signalling in skin.
Sunscreen active ingredients
ChemicalSubstance
Sunscreen actives divide into mineral and chemical filters. The clinically meaningful distinction is systemic absorption, not UV mechanism — both primarily absorb UV radiation.
Tallow
ChemicalSubstance
Rendered beef fat with a saturated and monounsaturated fatty acid profile compositionally similar to the free fatty acid fraction of healthy stratum corneum.
Telogen
BiologicalProcess
Hair resting phase lasting 2-4 months; normally only 10-15% of follicles are in this pre-shedding state at any time.
Telogen effluvium
MedicalCondition
A reactive hair loss condition in which a significant proportion of scalp follicles are simultaneously shifted into the resting phase by a systemic stressor.