Hair Preparations
Hair
Hair Follicle
Hair Cells, Auditory
Hair Cells, Auditory, Inner
Hair Cells, Vestibular
Hair Cells, Auditory, Outer
Chemical hair treatments and adverse pregnancy outcome among Black women in central North Carolina. (1/76)
Several studies suggest that toxic chemicals in hair products may be absorbed through the scalp in sufficient amounts to increase the risks of adverse health effects in women or their infants. This case-control study of 525 Black women from three counties in North Carolina who had delivered a singleton, liveborn infant examined whether exposure to chemicals used in hair straightening and curling increased the odds that the infant was preterm or low birth weight. Cases consisted of 188 preterm and 156 low birth weight births (for 123 women, their infant was both low birth weight and preterm). Controls were 304 women who delivered term and normal birth weight infants. Women who used a chemical hair straightener at any time during pregnancy or within 3 months prior to conception had an adjusted odds ratios (OR) of 0.7 (95% confidence interval (CI) 0.4-1.1) for preterm birth and 0.6 (95% CI 0.4-1.1) for low birth weight. Exposure to chemical curl products was also not associated with preterm delivery (adjusted OR = 0.9, 95% CI 0.5-1.8) or low birth weight (adjusted OR = 1.0, 95% CI 0.5-1.9). Despite this failure to find an association, continued search for risk factors to which Black women are uniquely exposed is warranted. (+info)Are cannabinoids detected in hair after washing with Cannabio shampoo? (2/76)
Today, cannabis plants are used in shampoo preparations, in foodstuffs (e.g., oils, noodles, crackers, etc.), and in beverages (e.g., tea). These products often contain < 1% delta9-tetrahydrocannabinol (THC) in order to eliminate psychoactive effects, but some of them can include 1 to 3% of THC. Gas chromatography-mass spectrometry (GC-MS) analysis of Cannabio shampoo revealed the presence of THC (412 ng/mL) and two constituents of cannabis plants, cannabidiol (CBD, 4079 ng/mL) and cannabinol (CBN, 380 ng/mL). In order to verify if normal hygiene practices with Cannabio shampoo can result in positive tests for cannabinoids in hair, three subjects washed their hair with this shampoo once daily for two weeks. After this period, hair specimens were collected. In the three hair specimens, THC, CBD, and CBN were never detected within their limits of detection, 0.05, 0.02, and 0.01 ng/mg, respectively. We concluded that the use of Cannabio shampoo during normal hygiene practices cannot be considered as a source of potential contamination of hair. In a second experiment, drug-free hair specimens (200 mg) were incubated in 10 mL water/Cannabio shampoo (20:1, v/v) for 30 min, 2 h, and 5 h. After incubation, hair strands were washed with water and separated into two portions. One portion was extracted directly; the second was decontaminated with methylene chloride and then extracted. After an incubation period of 30 min, the analysis of hair by GC-MS did not reveal the presence of THC, CBD, and CBN in hair, regardless of whether the hair was decontaminated. After an incubation period of 2 h, specimens tested positive for CBD (0.11 ng/mg without decontamination and 0.10 ng/mg with decontamination) and CBN (0.02 ng/mg without decontamination and 0.02 ng/mg after decontamination). After an incubation period of 5 h, specimens tested positive for CBD (0.25 ng/mg without decontamination and 0.14 ng/mg after decontamination) and CBN (0.02 ng/mg without decontamination and 0.02 ng/mg after decontamination). In all cases, THC was never detected. Extensive but unrealistic use of Cannabio shampoo can cause drug-free hair to test positive for CBD and CBN but not for the primary psychoactive drug THC. (+info)Epidemiologic studies of environmental agents and systemic autoimmune diseases. (3/76)
Systemic lupus erythematosus and systemic scleroderma are autoimmune diseases thought to have an exogenous trigger. This review summarizes relevant case-control and cohort studies that investigated exogenous sex hormones, silica, silicone, solvents, pesticides, mercuric chloride, and hair dyes as putative risk factors for the development of these diseases. These studies indicate that estrogen replacement therapy in postmenopausal women increases the risk of developing lupus, scleroderma, and Raynaud disease, although the increase in risk is relatively modest. Oral contraceptives may also play a role in disease susceptibility in lupus but not apparently in scleroderma. Environmental endocrine modulators, in the form of pesticides, may represent another opportunity for estrogenlike effects to occur, but there is scant evidence that these agents play a role in human systemic autoimmune disease. Although exposure to silica dust increases the risk of scleroderma in men occupied in the industry, this does not explain most male scleroderma cases. When this exposure was investigated among women, no significant risk was found. Additionally, silicone in implanted devices as well as occupational exposure to silicone-containing compounds did not pose an increased risk among women for scleroderma. The role of solvent exposure has been investigated as a risk factor for scleroderma with mixed findings. One study suggested a potential role in male patients or in those individuals with Scl-70 antibody positivity either male or female. Two other studies were unable to corroborate this finding. Mercuric chloride causes antifibrillarin antibodies and immune complex glomerulonephritis in susceptible mouse strains. Antifibrillarin antibodies, but not glomerulonephritis, occur in a subset of scleroderma patients and preliminary evidence suggests that mercury levels may be higher in this group of individuals. Hair products have been studied as possibly raising the risk of developing lupus, since such products contain an aromatic amine similar to a compound known to cause drug-induced lupus. A 1986 study suggested a positive association, but two subsequent studies did not support this association. (+info)Risk of hand dermatitis among hairdressers versus office workers. (4/76)
OBJECTIVES: The risk of irritant skin damage associated with hairdressing was estimated with the individual occupational exposure and other relevant factors having been taken into consideration. METHODS: A cohort of 2352 hairdressing and 111 office apprentices was prospectively followed for the duration of their vocational training (3 years), 3 examinations having been made and 3 years of recruitment having been used [1992 (hairdressers only), 1993, 1994] in 15 vocational training schools in northwest Germany. The information of the final follow-up examination was used for the analysis. RESULTS: A multifactorial analysis taking several (constitutional) risk factors, which were unevenly distributed between the 2 groups, into account revealed a significantly increased risk for hairdressers when compared with office workers (odds ratio approximately 4.0) with a marked decline in the most recently recruited (1994) apprentice group. Other significant factors increasing the dermatitis risk were (i) low ambient absolute humidity, (ii) young age, and (iii) a certain higher range of "atopy score". If the individual profile of occupational exposure among hairdressers was also considered, unprotected wet work of more than 2 hours per day was found to be a significant risk factor. CONCLUSIONS: Good skin protection, as operationalized in the present study, can diminish, but not eliminate, the risk of occupational irritant hand dermatitis among hairdressers. (+info)Infestation status of head louse and treatment with lindane shampoo in children of primary school and kindergarten in Chinju-shi, Kyongsangnam-do, Korea. (5/76)
The infestation status of head louse among children attending primary schools and kindergartens in Chinju-shi, Kyongsangnam-do, Korea, was investigated between June and July 1999. Out of 2,288 children examined, 3.9% of boys (48/1,242) and 23.5% of girls (246/1,046) were infested with nits or adult/nymphs of lice. The effectiveness of lindane shampoo (1% gamma benzene hexachloride solution) was evaluated after one or two time applications to all the children infested. The negative conversion rate of pediculosis was 93.5%. Effective control measures are needed to control and prevent such ectoparasite infestation amongst children. (+info)Treatment of seborrheic dermatitis. (6/76)
Seborrheic dermatitis is a chronic inflammatory disorder affecting areas of the head and trunk where sebaceous glands are most prominent. Lipophilic yeasts of the Malassezia genus, as well as genetic, environmental and general health factors, contribute to this disorder. Scalp seborrhea varies from mild dandruff to dense, diffuse, adherent scale. Facial and trunk seborrhea is characterized by powdery or greasy scale in skin folds and along hair margins. Treatment options include application of selenium sulfide, pyrithione zinc or ketoconazole-containing shampoos, topical ketoconazole cream or terbinafine solution, topical sodium sulfacetamide and topical corticosteroids. (+info)Prevalence of airway symptoms among hairdressers in Bergen, Norway. (7/76)
OBJECTIVE: To assess respiratory symptoms among hairdressers in Norway. METHODS: The study was based on a questionnaire sent to 100 hairdressers (91% responding) and 95 office workers (84% responding). The questionnaire sought information about allergy, respiratory symptoms in the past year, and symptoms after exposures to different types of pollutants, working conditions, and smoking habits. A population based control group was established because the hairdressers and office workers differed in age and smoking habits. RESULTS: The prevalence of respiratory symptoms in the past year did not differ significantly between hairdressers and office workers after adjusting for age, atopy, and smoking. The hairdressers over 40 years of age reported significantly more symptoms-such as wheezing and breathlessness-in the past year than the office workers of the same age. Compared with the population based control group, both hairdressers younger than 30 and those over 40 reported more symptoms-such as breathlessness in the past year. The oldest hairdressers reported such symptoms as wheezing and breathlessness more often than did the younger hairdressers. These differences in breathlessness were significant after adjusting for smoking and wheezing. The same trend was not found among the office workers. The hairdressers reported significantly more wheezing, breathlessness, runny eyes, and blocked or runny nose from exposure to hair dyes, permanent oils, bleaching powder, and other chemicals used in a hairdressing salon, compared with the office workers. Prevalence of symptoms during exposure to other types of generel pollutants was similar in the two groups. CONCLUSIONS: Hairdressers are exposed to low levels of various irritating chemicals every day. The prevalences of acute symptoms related to the exposure of hairdressers to hairdressing chemicals are very high. Hairdressers, especially the oldest hairdressers, have more asthma-like symptoms than the control groups. (+info)Incidence of asthma in female Swedish hairdressers. (8/76)
OBJECTIVE: To investigate the risk of asthma in hairdressers. METHODS: The incidence of asthma was retrospectively estimated in a Swedish nationwide study including all female hairdressers certified from vocational schools from 1970 to 1995, and a stratified sample of women from the general population were referents. A postal questionnaire included questions on respiratory tract symptoms, atopy, smoking, working periods as a hairdresser, and number of specific hair treatments performed/week. Reported exposures were validated by occupational hygienists. Rate ratios of incidence (IRRs) of asthma were estimated by Poisson regression, adjusted for calendar year of observation, hay fever, smoking, and region of domicile. RESULTS: The crude incidences of asthma/1000 person-years were: 3.9 during active years as a hairdresser, 2.8 among the hairdressers when not working in the profession, and 3.1 among the referents. The corresponding IRR for being an active hairdresser compared with the referents was 1.3 (95% confidence interval (95% CI) 1.0 to 1.6). Moderate effects on risk of asthma were found both from hairdressing work (IRR=1.6 (1.1 to 2.2) among never-smokers) and from smoking (IRR=1.6 (1.2 to 2.2) among referents). However, the combined effect from hairdressing work and smoking (IRR=1.5 (1.0 to 2.1)) was less than expected (p=0.02). No effect modification by respiratory atopy was found. The hairdressers most often performing hair bleaching treatments (IRR=1.5 (0.7 to 3.0)) or using hair spray (IRR=1.4 (0.8 to 2.4)) had, compared with the most infrequent users, a slightly, but not significantly higher incidence of asthma. Exposure to persulphates in hair bleach was estimated to be 0.04-0.15 mg/m(3) during mixing of the powder. Reported average number of bleaching treatments agreed well with those performed according to a diary. CONCLUSIONS: Active hairdressing work was associated with a moderately increased incidence of asthma among lifelong non-smokers. The results are moderately supportive, but not conclusive, of associations between asthma and exposure to hair bleach or hair spray. (+info)Hair preparations refer to cosmetic or grooming products that are specifically formulated to be applied to the hair or scalp for various purposes such as cleansing, conditioning, styling, coloring, or promoting hair growth. These preparations can come in different forms, including shampoos, conditioners, hair masks, serums, gels, mousses, sprays, and dyes. They may contain a wide range of ingredients, such as detergents, moisturizers, proteins, vitamins, minerals, and other nutrients that can help improve the health, appearance, and manageability of the hair. Some hair preparations may also contain medications or natural extracts that have therapeutic properties for treating specific hair or scalp conditions, such as dandruff, dryness, oiliness, thinning, or hair loss.
Medically, hair is defined as a threadlike structure that grows from the follicles found in the skin of mammals. It is primarily made up of a protein called keratin and consists of three parts: the medulla (the innermost part or core), the cortex (middle layer containing keratin filaments) and the cuticle (outer layer of overlapping scales).
Hair growth occurs in cycles, with each cycle consisting of a growth phase (anagen), a transitional phase (catagen), and a resting phase (telogen). The length of hair is determined by the duration of the anagen phase.
While hair plays a crucial role in protecting the skin from external factors like UV radiation, temperature changes, and physical damage, it also serves as an essential aspect of human aesthetics and identity.
A hair follicle is a part of the human skin from which hair grows. It is a complex organ that consists of several layers, including an outer root sheath, inner root sheath, and matrix. The hair follicle is located in the dermis, the second layer of the skin, and is surrounded by sebaceous glands and erector pili muscles.
The hair growth cycle includes three phases: anagen (growth phase), catagen (transitional phase), and telogen (resting phase). During the anagen phase, cells in the matrix divide rapidly to produce new hair fibers that grow out of the follicle. The hair fiber is made up of a protein called keratin, which also makes up the outer layers of the skin and nails.
Hair follicles are important for various biological functions, including thermoregulation, sensory perception, and social communication. They also play a role in wound healing and can serve as a source of stem cells that can differentiate into other cell types.
Auditory hair cells are specialized sensory receptor cells located in the inner ear, more specifically in the organ of Corti within the cochlea. They play a crucial role in hearing by converting sound vibrations into electrical signals that can be interpreted by the brain.
These hair cells have hair-like projections called stereocilia on their apical surface, which are embedded in a gelatinous matrix. When sound waves reach the inner ear, they cause the fluid within the cochlea to move, which in turn causes the stereocilia to bend. This bending motion opens ion channels at the tips of the stereocilia, allowing positively charged ions (such as potassium) to flow into the hair cells and trigger a receptor potential.
The receptor potential then leads to the release of neurotransmitters at the base of the hair cells, which activate afferent nerve fibers that synapse with these cells. The electrical signals generated by this process are transmitted to the brain via the auditory nerve, where they are interpreted as sound.
There are two types of auditory hair cells: inner hair cells and outer hair cells. Inner hair cells are the primary sensory receptors responsible for transmitting information about sound to the brain. They make direct contact with afferent nerve fibers and are more sensitive to mechanical stimulation than outer hair cells.
Outer hair cells, on the other hand, are involved in amplifying and fine-tuning the mechanical response of the inner ear to sound. They have a unique ability to contract and relax in response to electrical signals, which allows them to adjust the stiffness of their stereocilia and enhance the sensitivity of the cochlea to different frequencies.
Damage or loss of auditory hair cells can lead to hearing impairment or deafness, as these cells cannot regenerate spontaneously in mammals. Therefore, understanding the structure and function of hair cells is essential for developing therapies aimed at treating hearing disorders.
I'm sorry for any confusion, but "hair color" is not a term that has a medical definition in the same way that a term like "myocardial infarction" (heart attack) does. Hair color can be described in various ways, such as being a natural hair color (like blonde, brunette, red, or black) or describing a change in hair color due to factors like aging (gray or white hairs) or hair dye usage.
However, it's worth noting that changes in hair color can sometimes be associated with certain medical conditions. For example, premature graying of the hair before the age of 30 can be a feature of certain genetic disorders or vitamin B12 deficiency. Similarly, some skin conditions like alopecia areata or vitiligo can cause patchy changes in hair color. But these associations don't provide a medical definition for 'hair color'.
Hair diseases is a broad term that refers to various medical conditions affecting the hair shaft, follicle, or scalp. These conditions can be categorized into several types, including:
1. Hair shaft abnormalities: These are conditions that affect the structure and growth of the hair shaft. Examples include trichorrhexis nodosa, where the hair becomes weak and breaks easily, and pili torti, where the hair shaft is twisted and appears sparse and fragile.
2. Hair follicle disorders: These are conditions that affect the hair follicles, leading to hair loss or abnormal growth patterns. Examples include alopecia areata, an autoimmune disorder that causes patchy hair loss, and androgenetic alopecia, a genetic condition that leads to pattern baldness in both men and women.
3. Scalp disorders: These are conditions that affect the scalp, leading to symptoms such as itching, redness, scaling, or pain. Examples include seborrheic dermatitis, psoriasis, and tinea capitis (ringworm of the scalp).
4. Hair cycle abnormalities: These are conditions that affect the normal growth cycle of the hair, leading to excessive shedding or thinning. Examples include telogen effluvium, where a large number of hairs enter the resting phase and fall out, and anagen effluvium, which is typically caused by chemotherapy or radiation therapy.
5. Infectious diseases: Hair follicles can become infected with various bacteria, viruses, or fungi, leading to conditions such as folliculitis, furunculosis, and kerion.
6. Genetic disorders: Some genetic disorders can affect the hair, such as Menkes syndrome, which is a rare inherited disorder that affects copper metabolism and leads to kinky, sparse, and brittle hair.
Proper diagnosis and treatment of hair diseases require consultation with a healthcare professional, often a dermatologist or a trichologist who specializes in hair and scalp disorders.
Auditory inner hair cells are specialized sensory receptor cells located in the inner ear, more specifically in the organ of Corti within the cochlea. They play a crucial role in hearing by converting mechanical sound energy into electrical signals that can be processed and interpreted by the brain.
Human ears have about 3,500 inner hair cells arranged in one row along the length of the basilar membrane in each cochlea. These hair cells are characterized by their stereocilia, which are hair-like projections on the apical surface that are embedded in a gelatinous matrix called the tectorial membrane.
When sound waves cause the basilar membrane to vibrate, the stereocilia of inner hair cells bend and deflect. This deflection triggers a cascade of biochemical events leading to the release of neurotransmitters at the base of the hair cell. These neurotransmitters then stimulate the afferent auditory nerve fibers (type I fibers) that synapse with the inner hair cells, transmitting the electrical signals to the brain for further processing and interpretation as sound.
Damage or loss of these inner hair cells can lead to significant hearing impairment or deafness, as they are essential for normal auditory function. Currently, there is no effective way to regenerate damaged inner hair cells in humans, making hearing loss due to their damage permanent.
Hair removal is the deliberate elimination or reduction of body hair. This can be achieved through various methods, both temporary and permanent. Some common temporary methods include shaving, waxing, tweezing, and depilatory creams. Permanent methods may involve laser hair removal or electrolysis, which target the hair follicle to prevent future growth. It's important to note that some methods can have side effects or risks, so it's recommended to consult with a healthcare professional or dermatologist before starting any new hair removal regimen.
Hair dyes are chemical substances that are used to change the color of hair. They contain various types of dyes, including natural dyes derived from plants and minerals, synthetic dyes, and combinations of both. Hair dyes work by penetrating the outer layer of the hair shaft (the cuticle) and bonding with the hair's pigment (melanin) or depositing new color particles within the hair shaft.
There are three main types of hair dyes: temporary, semi-permanent, and permanent. Temporary hair dyes coat the outside of the hair shaft and wash out after a few shampoos. Semi-perermanent hair dyes penetrate slightly into the hair shaft and fade gradually over several washes. Permanent hair dyes contain chemicals that open the cuticle and allow the dye to penetrate deep into the hair shaft, where it reacts with the hair's natural pigment to create a new color that is resistant to fading and washing out.
It is important to note that some hair dyes may contain potentially harmful chemicals, such as coal tar dyes, para-phenylenediamine (PPD), and resorcinol, which have been linked to allergic reactions, skin irritation, and other health problems. It is recommended to perform a patch test before using any new hair dye product and to follow the manufacturer's instructions carefully to minimize the risk of adverse effects.
Vestibular hair cells are specialized sensory receptor cells located in the vestibular system of the inner ear. They play a crucial role in detecting and mediating our sense of balance and spatial orientation by converting mechanical stimuli, such as head movements and gravity, into electrical signals that are sent to the brain.
The hair cells are shaped like a tuft of hair, with stereocilia projecting from their tops. These stereocilia are arranged in rows of graded height, and they are embedded in a gel-like structure within the vestibular organ. When the head moves or changes position, the movement causes deflection of the stereocilia, which opens ion channels at their tips and triggers nerve impulses that are sent to the brain via the vestibular nerve.
There are two types of vestibular hair cells: type I and type II. Type I hair cells have a large, spherical shape and are more sensitive to changes in head position, while type II hair cells are more cylindrical in shape and respond to both linear and angular acceleration. Together, these hair cells help us maintain our balance, coordinate our movements, and keep our eyes focused during head movements.
Auditory outer hair cells are specialized sensory receptor cells located in the cochlea of the inner ear. They are part of the organ of Corti and play a crucial role in hearing by converting sound energy into electrical signals that can be interpreted by the brain.
Unlike the more numerous and simpler auditory inner hair cells, outer hair cells are equipped with unique actin-based molecular motors called "motile" or "piezoelectric" properties. These motors enable the outer hair cells to change their shape and length in response to electrical signals, which in turn amplifies the mechanical vibrations of the basilar membrane where they are located. This amplification increases the sensitivity and frequency selectivity of hearing, allowing us to detect and discriminate sounds over a wide range of intensities and frequencies.
Damage or loss of outer hair cells is a common cause of sensorineural hearing loss, which can result from exposure to loud noises, aging, genetics, ototoxic drugs, and other factors. Currently, there are no effective treatments to regenerate or replace damaged outer hair cells, making hearing loss an irreversible condition in most cases.