Measuring the frequency of consumer hair combing and magnitude of combing forces on individual hairs in a tress and the implications for product evaluation and claims substantiation.

OBJECTIVES: It is commonly assumed that, due to the long growth cycle of hair, multi-cycle combing, and strength and fatigue testing using thousands of cycles is relevant for product evaluation and claim substantiation. The objective was to assess the frequency and magnitude of combing forces on individual hairs against a hypothesis that fibres on a consumer's head rarely experience significant loads during routine combing. METHODS: Single fibres were removed from a tress, attached to a load cell and replaced in the tress. Combing of tresses, guided by in-vivo measurements, measured the frequency of significant loads defined as 'events' ≥1 g over 30 combing sets (set = 10 comb strokes @~25 cm s-1 ) with intermediate tangling. Asian and Caucasian hair was assessed by dry, wet, bleached-wet and bleached-dry combing. A questionnaire of 231 Asian and Caucasian women established daily frequency and number of comb strokes for the whole head. In-vivo combing videos of 10 women (five Asian, five Caucasian) were used to establish in-vivo and tress combing speeds. RESULTS: The questionnaires returned an average combing frequency of 1.7×/day (range 0-5) and average number of strokes 16 ± 2.3 per head/day (95% CI). Video analysis measured combing speeds of 22-35 cm s-1 across hair types. Tress data confirmed individual fibres are unlikely to experience repeated loading or significant loads in all but wet combed persulphate bleached hair. 'Events' of ≥1 g - dry combing gave an event probability of 0.2 and average load of 1.7 g over 30 comb sets. Dry combed bleached samples returned a probability of 0.23 and 0.3 respectively. Wet combed virgin Asian and Caucasian hair gave a probability of 0.1 and 0.47 respectively. Wet combed bleached hair gave a probability of one. The addition of a conditioner to bleached hair reduced the event probability to <0.1. CONCLUSION: During combing, individual fibres may not experience any significant loads and are unlikely to experience repetitive loads >10 g. The low number of comb strokes and low event probability is in keeping with consumers growing their hair long and in good condition. The data indicates the need for a significant rethink of methods used for product evaluation and claim substantiation.

DSC of human hair: a tool for claim support or incorrect data analysis?

Differential scanning calorimetry (DSC) data are increasingly used to substantiate product claims of hair repair. Decreasing peak temperatures may indicate structural changes and chemical damage. Increasing the DSC, wet peak temperature is, therefore, often considered as proof of hair repair. A detailed understanding of the technique and hair structure indicates that this may not be a sound approach. Surveying the rich literature on the use of dynamic thermal analysis (DTA) and differential scanning calorimetry (DSC) for the analyses of human hair and the effect of cosmetic treatments, we underline some of the problems of hair structure and data interpretation. To overcome some of the difficulties of data interpretation, we advise that DSC acquired data should be supported by other techniques when used for claim substantiation. In this way, one can provide meaningful interpretation of the hair science and robust data for product claims support.

An analytical method for the determination of betaine (trimethylglycine) from hair.

Hair fibres have no active renewable protective mechanisms yet hair (wool and fur) provides an essential protective function. Therefore, it is possible that hair contains a number of internal components to maintain fibre and protein structure and function through a range of normal environmental conditions. Trimethylglycine (betaine) provides cellular and protein protection during times of high osmotic stress and low water concentrations. These conditions are very pertinent to everyday cosmetic procedures such as shampooing, bleach or perming. Therefore, we have conducted preliminary investigations to establish the presence of natural betaine in hair as a possible ingredient to provide protection and maintain protein function. Using an high performance liquid chromatography (HPLC) technique designed for the analysis of betaine in blood and urine, we have demonstrated, via simple hot water extraction, a measurable level of betaine in blood and human hair. Further, we have demonstrated, in principle, the possibility of adding betaine back to the fibre via cosmetic products such as shampoos.

Acquired progressive kinking of hair. Report of six cases and review of literature.

Acquired progressive kinking of hair is an entity distinct from woolly hair in its onset at or after puberty, predominant involvement of frontal, temporal, and vertex regions of the scalp as well as the supra-auricular and postauricular margins, and a tendency for affected hairs to resemble pubic hair both in texture and color. We consider the condition to be androgen dependent and likely to progress to male pattern baldness. The condition "whisker hair" is probably a variant of acquired progressive kinking of hair.

The penetration of [14C]ethanol and [14C]methanol through excised guinea-pig skin in vitro.

We have studied the penetration in vitro of methanol and ethanol through excised, full thickness, guinea-pig skin. The total amount of methanol or ethanol that penetrated the skin over a period of 19 hr was in the order of 1% of the total dose. Neither compound appeared to show an increase in penetration with increasing dose volume. Penetration of both methanol and ethanol was significantly enhanced by occlusion. The amounts of both compounds that penetrated, and the profiles of the amount penetrating per hour, were significantly influenced by the nature of the occlusive material. Under occlusion and in the presence of either compound the barrier properties of the skin appeared to be altered so that 'fluid' was lost from or through the skin to the air space bounded by the occlusive material.

Elucidating penetration pathways into the hair fiber using novel microscopic techniques.

Much controversy exists regarding the route of penetration of molecules into hair fibers. In brief, there are two schools of thought. The first argument is that molecules enter the hair fiber via the cell membrane complex (cmc) of the cuticle and then diffuse throughout the cortex via both the intercellular cement and the bulk of individual cortical cells. The second approach concludes that entry to the fiber is via the endocuticle and other non-keratinous parts of the fiber. In the latter case the cmc is definitely not considered to have a role in the penetration of molecules into the fiber. The tools available for studying penetration into the fiber, e.g., light and electron microscopy, mean that it is usually only possible to extract static information from a dynamic process. Similarly, great care is needed in the interpretation of images produced by the various techniques. Where a molecule is seen to end up does not always indicate how it got there! In these studies I have used novel derivations of conventional electron microscopic techniques, combined with early photographic chemistry, to elucidate further the pathways of penetration into the hair fiber. From these studies one can conclude that both arguments describing penetration into the fiber are complementary, valid, and highly relevant. The techniques allow one to visualize material within the cell membrane complex of the cuticle. In addition, these studies show that the high-sulphur proteins of the cuticle, usually considered as highly cross-linked and inaccessible, are easily penetrated. Therefore, all of the structures within a hair fiber should be considered as penetration routes into the hair fiber for the delivery of industrial and cosmetic materials, even though they may not form continuous pathways throughout the hair. The hair should be viewed as a structure composed of a number of compartments of differing capacity, chemistry, and accessibility, rather than as continuous pathways from the surface to the center of the fiber.

Cosmetics and hair loss.

Cosmetic hair care products are often implicated by the user or the clinician in cases of hair loss. Yet, these products are used ad lib, in a wide variety of home conditions and on a wide variety of hair types, by millions of consumers every day with no adverse effects. Based on this extensive data set, the absence of literature reports, and a detailed understanding of the mode of action of cosmetic hair care products, we can conclude that they do not cause hair loss. Clinicians investigating cases of hair loss must fully appreciate the hair cycle, the length of time a single fibre may be present on the head, and its biological and cosmetic history in order to understand the causes of hair loss and make the correct diagnosis. With a better understanding of the cosmetic practices used by everyday consumers, the clinician will be in a strong position to help patients re-grow their hair and guide them through a high quality hair care regime.

Bubble hair: a cosmetic abnormality caused by brief, focal heating of damp hair fibres.

Following investigation of two individuals with bubble hair abnormality, a reproducible cause has been established. Simple experiments showed that brief, focal heating of damp hair is sufficient to cause bubbles to form inside the hair fibres. This in turn results in weak, dry and brittle hair which breaks easily.

Animal models for percutaneous penetration: assessing contamination of the experimental system.

We have used both quantitative and qualitative procedures to assess the validity of percutaneous penetration data obtained from the guinea-pig in vivo. Our results indicate that, under certain, not unusual, experimental conditions the results may be misleading and should be viewed with caution. Contamination of the experimental system, either by simple desquamation from the site of application, or trauma to the site such as rubbing or scratching, may greatly influence the results. We conclude that simple control experiments similar to those described should be conducted when using in vivo animal models for studies on percutaneous penetration, and particularly where the subject is not totally immobilized.

Loose anagen syndrome.

A distinctive new hair condition, the loose anagen syndrome, features anagen hairs that are loosely anchored and easily pulled from the scalp. The children studied had sparse hair that did not grow long and that pulled easily from the scalp. The majority of patients were blond girls, aged 2 to 5 years, but both sexes and those with dark hair can be affected. The hair was not fragile, and easily pulled hairs were misshapen anagen hairs without external root sheaths. Histologic examination of the hair showed abnormal premature keratinization of Huxley's and Henle's layers of the inner root sheath in some samples. Length and density of hair gradually increased with age, but anagen hairs remained loosely anchored in adulthood. This report describes findings in 22 children and five adults with the loose anagen syndrome.

Trichothiodystrophy: an ultrastructural study of the hair follicle.

We have used detailed ultrastructural and electron histochemical techniques on both the hair shaft and anagen hair follicle to elucidate further the structural abnormalities in trichothiodystrophic hair. We have shown that protein deposition in the follicle is reduced and lacks orientation, and that the anagen follicles show an overall distortion. Both the hair cuticle and cortex high sulphur protein components are affected. The results of this study help to give a visual interpretation to detailed biochemical studies conducted by other workers thereby allowing specific localization of the site of the intrinsic keratin abnormality.

Pili annulati: electron histochemical studies on affected hairs.

In this study we have shown that in pili annulati all the normal layers within each cuticle cell are present, and show a normal distribution of cystine. The presence of well ordered macrofibrils, composed of microfibrils embedded in a cystine rich matrix, in both regions of the hair shaft indicates that normal keratinization can and does take place. We have demonstrated the presence of electron-opaque, cystine positive material at the intermacrofibrillar spaces and suggest that the presence of the cortical holes is in part due to insufficient cortical material to occupy the space available, and in part due to the dissolution of the intermacrofibrillar material, possibly by water of other chemical agents, diffusing through an apparently more permeable cuticle.

Trichothiodystrophy: an electron-histochemical study of the hair shaft.

We have used sensitive electron-histochemical methods to study the subtle ultrastructural variations of cystine incorporation into the hair shaft in trichothiodystrophy. We have shown a general reduction in the cystine (sulphur) content of both the cuticle and the cortex. Discontinuity, and in some cases, complete absence of the cuticular A-layer results in premature weathering of the cuticle and weakening of the hair shaft. The ultrastructural findings support the work of Gillespie & Marshall (1981) in demonstrating the absence or re-characterization of the high sulphur matrix proteins and show further evidence for the incorporation, and abnormal distribution and deposition of sulphur-rich proteins in the hair cortex and cuticle. We conclude that the similar yet different results obtained from each patient's hair sample are characteristic of trichothiodystrophy, a neuro-ectodermal symptom complex which may represent a final common pathway of more than one metabolic disturbance.

Trichothiodystrophy-neurotrichocutaneous syndrome of Pollitt: a report of two unrelated cases.

Two unrelated children presenting with mental and physical retardation and sulphur deficient brittle hair are reported. These are thought to be further cases of the autosomal recessive neurotrichocutaneous syndrome of Pollitt, of which eight cases have been previously reported.

2-in-1 shampoo technology: state-of-the-art shampoo and conditioner in one.

Consumers have expressed a need for cleaning and conditioning in one step. Conventional shampoo technology using anionic surfactants and cationic conditioners results in charge interaction and complexing of the ingredients. Neither shampoo nor conditioners achieves the desired result. The successful solution was to incorporate charge neutral dimethicone conditioning ingredients, suspended as microfine droplets within complex crystal lattices, into anionic surfactant shampoo technology. The same solution has also been applied to amphoteric surfactant systems. This provides complete cleaning, and hair conditioning fully equal to separate conditioners without the problems of sebum interactions and conditioner build-up. This was achieved by keeping the dimethicone in suspension throughout the shampoo process. During rinsing, excess water breaks the crystalline lattice and allows deposition of the dimethicone droplets onto the hair. Full cleaning and conditioning are, therefore, achieved in one application. Dimethicone build-up is not encountered as subsequent washes first remove soil and previously deposited dimethicone. Neither do neutral dimethicones show any reactions with sebum. The development of effective 2-in-1 technology has had a major impact on shampoo technology and consumer habits and practices. This has significantly changed the way consumers care for their hair.

Generalized trichorrhexis nodosa.

A case of generalized trichorrhexis nodosa is described in a man. Electron histochemical studies showed abnormal staining consistent with a definite disorder in the formation of alpha-keratin chains within the globular matrix of the hair cortex with respect to cystine; keratin amino-acid analysis also revealed low cystine. This cortical change, together with multiple vacuoles found in the endocuticle, are evidently the intrinsic defects which allow relatively trivial chemical and physical trauma to cause trichorrhexis nodosa.

Monilethrix: an electron microscopic and electron histochemical study.

We have carried our electron microscopic and electron histochemical investigations on affected hair follicles and hair shafts to elucidate further the structural abnormality in monilethrix. The structural abnormalities manifest in the cortex and cuticle of the hair shaft could be traced to the locality of the 'zone of keratinization' of the follicle. Abnormal orientation of the cortical cell proteins, folding of the cuticle cell membrane and varying amounts of endocuticular material were all observed in the region prior to full keratinization. We observed structural abnormalities within all the component layers of the inner root sheath adjacent to the faults within the hair shaft, indicating a possible asynchrony within the monilethrix follicle.

The distribution of Mycobacterium leprae in the hair follicle of the eyebrow.

Longitudinal sections of hair follicles from the eyebrows of patients with active, untreated, lepromatous leprosy were studied. Mycobacterium leprae were found in the dermal papilla and outer root sheath of both anagen and telogen hair follicles. Bacilli were rarely found in those cell lines continuous with the environment, i.e., the hair shaft and the inner root sheath. The biochemical fate of these cell lines is such that they would not provide a suitable medium for the survival and transport of bacilli into the environment. We conclude that it is unlikely that the hair follicle plays a significant role in the dissemination of M. leprae but it may be important in providing a suitable site for the incubation of the bacillus within the dermis.

Kwashiorkor: an electron histochemical study of the hair shaft.

Previous studies on hair in kwashiorkor have been equivocal regarding the normal or abnormal incorporation of amino acids into the hair shaft. In this study we have applied a sensitive electron histochemical technique to transverse sections of scalp hair from children with severe kwashiorkor in order to study its ultrastructure and the incorporation of sulphur-containing amino acids (cystine). We have found no evidence to support the idea that a protein deficient diet in the weaning or post-weaning period directly affects the distribution and relative amounts of sulphur-containing amino acids in the hair shaft in this disease.