Botulinum toxin, one of the most poisonous biological substances known, is a neurotoxin produced by the bacterium Clostridium botulinum. C. botulinum elaborates eight antigenically distinguishable exotoxins (A, B, C1, C2, D, E, F and G). All serotypes interfere with neural transmission by blocking the release of acetylcholine, the principal neurotransmitter at the neuromuscular junction, causing muscle paralysis. The weakness induced by injection with botulinum toxin A usually lasts about three months. Botulinum toxins now play a very significant role in the management of a wide variety of medical conditions, especially strabismus and focal dystonias, hemifacial spasm, and various spastic movement disorders, headaches, hypersalivation, hyperhidrosis, and some chronic conditions that respond only partially to medical treatment. The list of possible new indications is rapidly expanding. The cosmetological applications include correction of lines, creases and wrinkling all over the face, chin, neck, and chest to dermatological applications such as hyperhidrosis. Injections with botulinum toxin are generally well tolerated and side effects are few. A precise knowledge and understanding of the functional anatomy of the mimetic muscles is absolutely necessary to correctly use botulinum toxins in clinical practice.
Untoward reactions to cosmetics, toiletries, and topical applications are the commonest single reason for hospital referrals with allergic contact dermatitis. In most cases, these are only mild or transient and most reactions being irritant rather than allergic in nature. Various adverse effects may occur in the form of acute toxicity, percutaneous absorption, skin irritation, eye irritation, skin sensitization and photosensitization, subchronic toxicity, mutagenicity/genotoxicity, and phototoxicity/photoirritation. The safety assessment of a cosmetic product clearly depends upon how it is used, since it determines the amount of substance which may be ingested, inhaled, or absorbed through the skin or mucous membranes. Concentration of ingredients used in the different products is also important. Various test procedures include in vivo animal models and in vitro models, such as open or closed patch test, in vivo skin irritation test, skin corrosivity potential tests (rat skin transcutaneous electrical resistance test, Episkin test), eye irritation tests (in vivo eye irritancy test and Draize eye irritancy test), mutagenicity/genotoxicity tests (in vitro bacterial reverse mutation test and in vitro mammalian cell chromosome aberration test), and phototoxicity/photoirritation test (3T3 neutral red uptake phototoxicity test). Finished cosmetic products are usually tested in small populations to confirm the skin and mucous membrane compatibility, and to assess their cosmetic acceptability.
Oral glucose tolerance studies were carried out In 118 non-hospitalised patients with acrochordon. 36 (30.5%) patients had overt diabetes wellitus while impaired glucose tolerance was observed in 12 (10.1%) cases. There was no distinct correlation between the localisation, size, colour and number of the skin tags with glucose intolerance.
Thyroid disturbances are common in women during the reproductive years of their lives. Autoimmunity and altered iodine status together account for a high proportion of the abnormalities. Autoimmune thyroid disease is present in around 4% of young females, and up to 15% are at risk because they are thyroid antibody-positive. There is a strong relationship between thyroid immunity on the one hand and infertility, miscarriage, and thyroid disturbances in pregnancy and postpartum on the other hand. Suboptimal iodine status affects a large proportion of the world's population, and pregnancy further depletes iodine stores. There is controversy surrounding the degree to which iodine should be supplemented and the duration of supplementation. Recent studies have helped to clarify the relationship between maternal thyroid status and neuropsychological development of the child. The role of other environmental factors including smoking and selenium status is also now recognised. Universal screening for thyroid hormone abnormalities is not routinely recommended at present. However, measurement of thyroid function and autoantibodies should certainly be considered in those who are at high risk of thyroid disease and in those whose pregnancy is otherwise high risk. The practicing clinician needs to be aware of the thyroid changes which accompany pregnancy.
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