Hair has a significant physical, psychological and social impact on an individual's daily life and well being. Understanding the basic structure and the factors that affect hair fiber integrity leads to better handling and care of our hair.
Hair is a slowly renewable protein fiber which grows at a rate of about 1 cm per month. Once hair emerges from the scalp, it is a non living matter.' From the scalp exit point to the distal portion of the hair strand, any injury to the hair structure is irreversible. Subjecting the hair fiber to the least amount of dailytrauma helps to minimize any damage to the hair fiber.
Hair fiber is mainly keratin protein and a small amount of lipid and other components. It is made up of an inner cortex, medulla and an external cuticle layer. The hair cuticle is made up of overlapping cell layers (approximately 5-10 layers) which covers the entirehair fiber. Each cuticular cell has inner layers (A layer and the endocuticle), outer sublamellar structures and an outer membrane, containing lipids mainly 18-methyl eicosanoic acid which imparts a hydrophobic nature to the cuticle.' The condition of the cuticle mainly determines the cosmetic appearance of the hair and being the most external layer, is the part of the hair most vulnerable to the effects of daily grooming, cosmetic treatments and the environment.
The cortex has a winded helical configuration of long microfibers linked to each other to form larger structures which gives the hair its tensile strength and elasticity." The inner location of the cortex makes it less prone to damage thus injury to the cortex signifies more severe damage to the outer cuticles allowing extension to the inner cortex. The medulla is the innermost cylindrical part of the hair fiber whose function is not as clear as the other two structures.

Human ; Male ; Female ; Eicosanoic Acids ; Elasticity ; Grooming ; Hair ; Keratins ; Lipids ; Scalp ; Scleroproteins ; Tensile Strength

BACKGROUND: It has been known that arteries of hypertensive animals and patients are generally thicker and more rigid than those of normal subjects, resulting from the morphological changes induced by an increased stress on the vessel wall. Factors proposed to be responsible for these changes are smooth muscle hypertrophy, increased amount of collagen, hyperplasia of smooth muscle cell and changes in cross-linkages of the fibrous proteins. The present study was conducted to define whether enalapril, a converting enzyme inhibitor of angiotensin II generation from angiotensin I, can restore the structural alterations of aortic media in spontaneously hypertensive rat(SHR). METHODS: For this purpose, SHR were treated for 22 weeks with 2mg/kg/day enalapril and morphologic changes were compared between enalapril-treated SHR and normotensive Wistar-Kyoto rats. RESULTS: The increased thickness of the aortic media in SHR was reduced and intervening elastic laminae were narrowed by enalapril treatment. Subcellular analysis of cytoplasmic composition and nucleus in the aorta of hypertensive rats revealed some modification with enalapril. Some irregularly arranged collagen fibrils in aortic media of SHR were regularly distributed and the periodic bands of the fibrils which were the fragmented were clearly apparent by enalapril treatmed SHR group. CONCLUSIONS: From the above experimental results, it is concluded that subcellular changes of smooth muscle cells and collage fibrils of aortic media in SHR could be repaired by long-term treatment with enalapril.
Angiotensin I ; Angiotensin II ; Animals ; Aorta ; Arteries ; Collagen ; Cytoplasm ; Enalapril* ; Humans ; Hyperplasia ; Hypertrophy ; Muscle, Smooth ; Myocytes, Smooth Muscle ; Rats ; Rats, Inbred SHR* ; Scleroproteins

BACKGROUND: The fibrous proteins of extracellular matrix (ECM) produced by dermal fibroblast contributes to the maintenance of connective tissue integrity. OBJECTIVE: This study is carried out to identify the bioactive ingredient from natural products that enhances ECM production in dermal fibroblasts. METHODS: Bioassay-directed fractionation was used to isolate the active ingredient from natural extracts. The effects of rasatiol (isolated from Raphanus sativus) on ECM production in primary cultured human dermal fibroblasts was investigated by enzyme linked immunosorbent assay and western blot analysis. RESULTS: Rasatiol accelerated fibroblast growth in a dose-dependent manner and increased the production of type 1 collagen, fibronectin and elastin. Phosphorylation of p42/44 extracellular signal-regulated kinase, p38 mitogen-activated protein kinase, and Akt was remarkably increased by rasatiol, indicating that enhanced ECM production is linked to the activation of intracellular signaling cascades. CONCLUSION: These results indicate that rasatiol stimulates the fibrous components of ECM production, and may be applied to the maintenance of skin texture.
Biological Agents ; Blotting, Western ; Collagen Type I ; Connective Tissue ; Elastin ; Enzyme-Linked Immunosorbent Assay ; Extracellular Matrix ; Fibroblasts ; Fibronectins ; Humans ; Phosphorylation ; Phosphotransferases ; Protein Kinases ; Raphanus ; Scleroproteins ; Skin

BACKGROUND: The fibrous proteins of extracellular matrix (ECM) produced by dermal fibroblast contributes to the maintenance of connective tissue integrity. OBJECTIVE: This study is carried out to identify the bioactive ingredient from natural products that enhances ECM production in dermal fibroblasts. METHODS: Bioassay-directed fractionation was used to isolate the active ingredient from natural extracts. The effects of rasatiol (isolated from Raphanus sativus) on ECM production in primary cultured human dermal fibroblasts was investigated by enzyme linked immunosorbent assay and western blot analysis. RESULTS: Rasatiol accelerated fibroblast growth in a dose-dependent manner and increased the production of type 1 collagen, fibronectin and elastin. Phosphorylation of p42/44 extracellular signal-regulated kinase, p38 mitogen-activated protein kinase, and Akt was remarkably increased by rasatiol, indicating that enhanced ECM production is linked to the activation of intracellular signaling cascades. CONCLUSION: These results indicate that rasatiol stimulates the fibrous components of ECM production, and may be applied to the maintenance of skin texture.
Biological Agents ; Blotting, Western ; Collagen Type I ; Connective Tissue ; Elastin ; Enzyme-Linked Immunosorbent Assay ; Extracellular Matrix ; Fibroblasts ; Fibronectins ; Humans ; Phosphorylation ; Phosphotransferases ; Protein Kinases ; Raphanus ; Scleroproteins ; Skin