see aspartate aminotransferase.
Cause Asthma runs in families, so that parents with asthma have a strong risk of having children with asthma, or with other atopic (see ATOPY) illnesses such as HAY FEVER or eczema (see DERMATITIS). There is therefore a great deal of interest in the genetic basis of the condition. Several GENES seem to be associated with the condition of atopy, in which subjects have a predisposition to form ANTIBODIES of the IgE class against allergens (see ALLERGEN) they encounter – especially inhaled allergens.
The allergic response in the lining of the airway leads to an in?ammatory reaction. Many cells are involved in this in?ammatory process, including lymphocytes, eosinophils, neutrophils and mast cells. The cells are attracted and controlled by a complex system of in?ammatory mediators. The in?amed airway-wall produced in this process is then sensitive to further allergic stimuli or to non-speci?c challenges such as dust, smoke or drying from the increased respiration during exercise. Recognition of this in?ammation has concentrated attention on anti-in?ammatory aspects of treatment.
Continued in?ammation with poor control of asthma can result in permanent damage to the airway-wall such that reversibility is reduced and airway-narrowing becomes permanent. Appropriate anti-in?ammatory therapy may help to prevent this damage.
Many allergens can be important triggers of asthma. House-dust mite, grass pollen and animal dander are the commonest problems. Occupational factors such as grain dusts, hard-metals fumes and chemicals in the plastic and paint industry are important in some adults. Viral infections are another common trigger, especially in young children.
The prevalence of asthma appears to be on the increase in most countries. Several factors have been linked to this increase; most important may be the vulnerability of the immature immune system (see IMMUNITY) in infants. High exposure to allergens such as house-dust mite early in life may prime the immune system, while reduced exposure to common viral infections may delay the maturation of the immune system. In addition, maternal smoking in pregnancy and infancy increases the risk.
Clinical course The major symptoms of asthma are breathlessness and cough. Occasionally cough may be the only symptom, especially in children, where night-time cough may be mistaken for recurrent infection and treated inappropriately with antibiotics.
The onset of asthma is usually in childhood, but it may begin at any age. In childhood, boys are affected more often than girls but by adulthood the sex incidence is equal. Children who have mild asthma are more likely to grow out of the condition as they go through their teenaged years, although symptoms may recur later.
The degree of airway-narrowing, and its change with time and treatment, can be monitored by measuring the peak expiratory ?ow with a simple monitor at home – a peak-?ow meter. The typical pattern shows the peak ?ow to be lowest in the early morning and this ‘morning dipping’ is often associated with disturbance of sleep.
Acute exacerbations of asthma may be provoked by infections or allergic stimuli. If they do not respond quickly and fully to medication, expert help should be sought urgently since oxygen and higher doses of drugs will be necessary to control the attack. In a severe attack the breathing rate and the pulse rate rise and the chest sounds wheezy. The peak-?ow rate of air into the lungs falls. Patients may be unable to talk in full sentences without catching their breath, and the reduced oxygen in the blood in very severe attacks may produce the blue colour of CYANOSIS in the lips and tongue. Such acute attacks can be very frightening for the patient and family.
Some cases of chronic asthma are included in the internationally agreed description CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) – a chronic, slowly progressive disorder characterised by obstruction of the air?ow persisting over several months.
Treatment The ?rst important consideration in the treatment of asthma is avoidance of precipitating factors. When this is a speci?c animal or occupational exposure, this may be possible; it is however more di?cult for house-dust mite or pollens. Exercise-induced asthma should be treated adequately rather than avoiding exercise.
Desensitisation injections using small quantities of speci?c allergens are used widely in some countries, but rarely in the UK as they are considered to have limited value since most asthma is precipitated by many stimuli and controlled adequately with simple treatment.
There are two groups of main drugs for the treatment of asthma. The ?rst are the bronchodilators which relax the smooth muscle in the wall of the airways, increase their diameter and relieve breathlessness. The most useful agents are the beta adrenergic agonists (see ADRENERGIC RECEPTORS) such as salbutamol and terbutaline. They are best given by inhalation into the airways since this reduces the general side-effects from oral use. These drugs are usually given to reverse airway-narrowing or to prevent its onset on exercise. However, longer-acting inhaled beta agonists such as salmeterol and formoterol or the theophyllines given in tablet form can be used regularly as prevention. The beta agonists can cause TREMOR and PALPITATION in some patients.
The second group of drugs are the antiin?ammatory agents that act to reduce in?ammation of the airway. The main agents in this group are the CORTICOSTEROIDS. They must be taken regularly, even when symptoms are absent. Given by inhalation they have few side-effects. In acute attacks, short courses of oral steroids are used; in very severe disease regular oral steroids may be needed. Other drugs have a role in suppressing in?ammation: sodium cromoglycate has been available for some years and is generally less e?ective than inhaled steroids. Newer agents directed at speci?c steps in the in?ammatory pathway, such as leukotriene receptor-antagonists, are alternative agents.
Treatment guidelines have been produced by various national and international bodies, such as the British Thoracic Society. Most have set out treatment in steps according to severity, with objectives for asthma control based on symptoms and peak ?ow. Patients should have a management plan that sets out their regular treatment and their appropriate response to changes in their condition.
Advice and support for research into asthma is provided by the National Asthma Campaign.
See www.brit-thoracic.org.uk
Prognosis Asthma is diagnosed in 15–20 per cent of all pre-school children in the developed world. Yet by the age of 15 it is estimated that fewer than 5 per cent still have symptoms. A study in 2003 reported on a follow-up of persons born in 1972–3 who developed asthma and still had problems at the age of nine. By the time these persons were aged 26, 27 per cent were still having problems; around half of that number had never been free from the illness and the other half had apparently lost it for a few years but it had returned.... asthma
Astrocytomas are the most common type of glioma, a tumour arising from the glial (supporting) cells in the nervous system.
They most commonly develop in the cerebrum (the main mass of the brain).
Astrocytomas are classified in 4 grades (I–) according to their rate of growth and malignancy.
The most severe type is called glioblastoma multiforme.
Symptoms are similar to those of other types of brain tumour.
Diagnostic tests include CT scanning or MRI.
Treatment is with surgery and, in some cases, radiotherapy in addition.... astrocytoma
Habitat: Common in moist places, paddy fields, throughout India and Sri Lanka.
Ayurvedic: Kokilaaksha, Kokilaak- shi, Ikshura, Ikshuraka, Kaakekshu, Kshurak, Bhikshu.Unani: Taalmakhaanaa. (Wrongly equated with Euryaleferox Salisb. (Fox Nut) in National Formulary of Unani Medicine, Part I, first edn., 1981.)Siddha/Tamil: Neermulli, Nerugobbi.Action: Diuretic, used for catarrh of the urinary organs, also for dropsy when accompanied by hepatic obstruction.
The Ayurvedic Pharmacopoeia ofIn- dia recommends the seed in lithiasis; the whole plant and root for gout.Aqueous extract of herb ash—diuretic in albino rats. EtOH (50%)— spasmolytic and hypotensive. The herb exhibits antihepatotoxic activity in dogs. Essential oil from whole plant—antibacterial.The plant gave lupeol, stigmasterol and hydrocarbons; seed gave sterols; flowers, apigenin glucuronide.Aqueous extract decreased fasting glucose and improved glucose tolerance in rats. (Sharon M. Herr.)Dosage: Whole plant—3-6 g, powder; dried seed—3-6 g powder; dried root—3-6 g for decoction. (API Vol. II.) Herb ash—1-3 g (CCRAS.)... asteracantha longifoliaHabitat: The western Himalayas.
Ayurvedic: Rudanti, Rudravanti.Action: Depurative, bechic, blood purifier (used in skin diseases). Root powder and decoction also used as an adjunct in tuberculosis.
Dosage: Fruit—3-5 g powder. (CCRAS.)... astragalus candolleanusHabitat: The western Himalayas at 2,400-3,900 m, and Kashmir.
English: Indian Gum tragacanth.Action: Gum—an Indian substitute for tragacanth (A. gummifer gum).... astragalus strobiliferus
Astread, Astreed, Astrad, Astri, Astrod, Astrud, Astryd, Astrida, Astrik, Astred, Astlyr, Astlyrd... astrid
Habitat: Highlands of Asia Minor, Iran, Greece, Syria and Russia.
English: Tragacanth Gum.Unani: Katiraa, Kataad (Gum)Action: Demulcent, emollient (used for irritation of the internal mucosa, colitis, dry coughs), laxative. Mucilage used as an application to burns.
The gum contains polysaccharides and proteinaceous polysaccharides.Tragacanthin is water-soluble, consisting of an arbinogalactan and traga- canthic acid. Bassorin is an insoluble methylated fraction (gel). The polysac- charides have been shown to have im- munostimulating activity (stimulation of phagocytosis and an increase in plasma cell counts of T-lymphocytes.Although tragacanth increases weight of stool and decreases gastrointestinal transit time, it does not appear to affect cholesterol triglyceride or phospholipid levels as other soluble fibres do. (Natural Medicines Comprehensive Database, 2007.)Tragacanth has been shown to be active against a variety of tumours. It appears to inhibit growth of cancer cells.... astragalus gummiferHabitat: Found in the plains of Punjab.
English: Tonkin bean, Melilot, King's crown, King's clover.Unani: Naakhunaa, Ikil-ul-Malik. (It is also equated with Melilotus alba Desv. and Trigonela uncata Boiss. in National Formulary of Unani Medicine.)Action: Nervine tonic (used in nervous and catarrhal affections), antirheumatic, anti-inflammatory, emollient, diuretic, galactogenic.
The callus of the plant contains amino acids; roots contain saponins and sterols. The leaves yield 3-nitro- propionic acid.... astragalus hamosusHabitat: The mountainous regions from Asia Minor to Iraq and Iran.
English: Sarcocola.Ayurvedic: Rudanti (substitute).Unani: Anzaroot, Kohal Kirmaani (Gum).Action: Gum—antirheumatic, aperient, anthelmintic, emollient.
The rootbark yields alkaloids, atala- phylline and its N-methyl derivatives and atalaphyllidine, which have close structural similarities with the antitu- mour alkaloid, acronycine, and its co- geners. The rootbark also contains the limonoid, atalantin.The leaf juice forms an ingredient of a compound liniment used in hemiplegia. The essential oil is used in paralysis. The oil contains higher terpene esters belonging to azulene group (29%). (Azulenes impart anti-inflammatory activity.)... astragalus sarcocolaIn some instances a planet cures by acting in sympathy, each planet curing its own disease; i.e. Venus and diseases of the reproductive system.
It is an ancient herbal practise for herbs to be gathered when the ruling planet is in the ascendancy. Scientific inquiry fails to support this system of medical treatment. ... astrology
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