n. the process of attaining full development. The term is applied particularly to the development of mature germ cells (ova and sperm).
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
Habitat: Native to the West Indies and tropical America; now cultivated throughout tropical regions of India.
English: Chilli, Red Pepper.Ayurvedic: Raktamaricha, Lankaa, Katuviraa.Unani: Mirch, Filfil-e-Ahmar, Filfl-e-Surkh, Surkh Mirch.Siddha/Tamil: Milagay.Action: Stimulant, accelerates oxygenation of cells, encourages adrenal glands to produce corticos- teroids, increases gastrointestinal secretion. Carminative, antispas- modic, antiseptic. Used externally for rheumatism, backache, lumbago, neuralgia, painful muscle spasm.
Red chilli contains capsaicin (0.11.5%), carotenoids, flavonoids, volatile oil; steroidal saponins (capsicidins, only in seeds).Capsaicin stimulates the circulation and alters temperature regulation; topically desensitizes nerve endings and acts as a local analgesic.Capsaicin produces a protective effect in rat lung and liver by strengthening the pulmonary antioxidant enzyme defence system. Acute capsaicin treatment causes release of substance desensitization of the respiratory tract mucosa to a variety of lung irritants.Red pepper or an equivalent amount of capsaicin, when fed along with cholesterol-containing diets to female albino rats, prevented significantly the rise of liver cholesterol levels.Vitamin P has been isolated from the chillies. Vitamin C gradually increases during maturation and reaches maximum at the semi-ripe or pink coloured stage and decreases thereafter.Capsaicin exhibited a hypoglycae- mic effect in dogs; insulin release was increased. (Phytother Res, 2001, Aug 15(5), 391-4.)Dosage: Fruit—30-60 mg powder. (CCRAS.)... capsicum annuumDisturbed bladder control can also result from nerve degeneration in conditions such as diabetes mellitus, multiple sclerosis, or dementia. An unstable or irritable bladder is a common condition and is sometimes associated with a urinary tract infection or prolapse of the uterus. Tension or anxiety can cause frequent urination. In children, delayed bladder control (see enuresis) most often results from delayed maturation of the nervous system.... bladder, disorders of
It may also be caused by vitamin deficiency, injury, or infection of a primary tooth that interferes with enamel maturation.... hypoplasia, enamel
Sometimes during cell division chromosomes may be lost or duplicated, or abnormalities in the structure of individual chromosomes may occur. The surprising fact is the infrequency of such errors. About one in 200 live-born babies has an abnormality of development caused by a chromosome, and two-thirds of these involve the sex chromosomes. There is little doubt that the frequency of these abnormalities in the early embryo is much higher, but because of the serious nature of the defect, early spontaneous ABORTION occurs.
Chromosome studies on such early abortions show that half have chromosome abnormalities, with errors of autosomes being three times as common as sex chromosome anomalies. Two of the most common abnormalities in such fetuses are triploidy with 69 chromosomes and trisomy of chromosome 16. These two anomalies almost always cause spontaneous abortion. Abnormalities of chromosome structure may arise because of:
Deletion Where a segment of a chromosome is lost.
Inversion Where a segment of a chromosome becomes detached and re-attached the other way around. GENES will then appear in the wrong order and thus will not correspond with their opposite numbers on homologous chromosomes.
Duplication Where a segment of a chromosome is included twice over. One chromosome will have too little nuclear material and one too much. The individual inheriting too little may be non-viable and the one with too much may be abnormal.
Translocation Where chromosomes of different pairs exchange segments.
Errors in division of centromere Sometimes the centromere divides transversely instead of longitudinally. If the centromere is not central, one of the daughter chromosomes will arise from the two short arms of the parent chromosome and the other from the two long arms. These abnormal daughter chromosomes are called isochromosomes.
These changes have important bearings on heredity, as the e?ect of a gene depends not only upon its nature but also upon its position on the chromosome with reference to other genes. Genes do not act in isolation but against the background of other genes. Each gene normally has its own position on the chromosome, and this corresponds precisely with the positon of its allele on the homologous chromosome of the pair. Each member of a pair of chromosomes will normally carry precisely the same number of genes in exactly the same order. Characteristic clinical syndromes, due to abnormalities of chromosome structure, are less constant than those due to loss or gain of a complete chromosome. This is because the degree of deletion, inversion and duplication is inconstant. However, translocation between chromosomes 15 and 21 of the parent is associated with a familial form of mongolism (see DOWN’S (DOWN) SYNDROME) in the o?spring, and deletion of part of an X chromosome may result in TURNER’S SYNDROME.
Non-disjunction Whilst alterations in the structure of chromosomes arise as a result of deletion or translocation, alterations in the number of chromosomes usually arise as a result of non-disjunction occurring during maturation of the parental gametes (germ cells). The two chromosomes of each pair (homologous chromosomes) may fail to come together at the beginning of meiosis and continue to lie free. If one chromosome then passes to each pole of the spindle, normal gametes may result; but if both chromosomes pass to one pole and neither to the other, two kinds of abnormal gametes will be produced. One kind of gamete will contain both chromosomes of the pair, and the other gamete will contain neither. Whilst this results in serious disease when the autosomes are involved, the loss or gain of sex chromosomes seems to be well tolerated. The loss of an autosome is incompatible with life and the malformation produced by a gain of an autosome is proportional to the size of the extra chromosome carried.
Only a few instances of a gain of an autosome are known. An additional chromosome 21 (one of the smallest autosomes) results in mongolism, and trisomy of chromosome 13 and 18 is associated with severe mental, skeletal and congenital cardiac defects. Diseases resulting from a gain of a sex chromosome are not as severe. A normal ovum contains 22 autosomes and an X sex chromosome. A normal sperm contains 22 autosomes and either an X or a Y sex chromosome. Thus, as a result of nondisjunction of the X chromosome at the ?rst meiotic division during the formation of female gametes, the ovum may contain two X chromosomes or none at all, whilst in the male the sperm may contain both X and Y chromosomes (XY) or none at all. (See also CHROMOSOMES; GENES.)... sex chromosomes
Minor variations from the mean do not warrant investigation, but if the height of an individual falls below the third centile (3 per cent of normal children have a height that falls below the third centile) or above the 97th centile, investigation is required. Changes in the rate of growth are also important, and skeletal proportions may provide useful information. There are many children who are normal but who are small in relation to their parents; the problem is merely growth delay. These children take longer to reach maturity and there is also a proportional delay in their skeletal maturation – so that the actual height must always be assessed in relation to maturity. The change in skeletal proportions is one manifestation of maturity, but other features include the maturing of facial features with the growth of nose and jaw, and dental development. Maturity of bone can readily be measured by the radiological bone age.
Failure to gain weight is of more signi?cance. Whilst this may be due to some underlying disease, the most common cause is a diet containing inadequate calories (see CALORIE). Over the last six decades or so there has been quite a striking increase in the heights and weights of European children, with manufacturers of children’s clothing, shoes and furniture having to increase the size of their products. Growth is now completed at 20–21 years, compared with 25 at the turn of the century. It has been suggested that this increase, and earlier maturation, have been due to a combination of genetic mixing as a result of population movements, with the whole range of improvement in environmental hygiene – and not merely to better nutrition.
In the case of adults, views have changed in recent years concerning ‘ideal’ weight. Life-insurance statistics have shown that maximal life expectancy is obtained if the average weight at 25–30 years is maintained throughout the rest of life. These insurance statistics also suggest that it is of advantage to be slightly over the average weight before the age of 30 years; to be of average weight after the age of 40; and to be underweight from ages 30–40. In the past it has been usual, in assessing the signi?cance of an adult’s weight, to allow a 10 per cent range on either side of normal for variations in body-build. A closer correlation has been found between thoracic and abdominal measurements and weight.... weight and height
If a child wets the bed persistently, tests, including urinalysis, may be performed to rule out a physical cause. For bed-wetting that is not caused by a disorder, treatment starts with training the child to pass urine regularly during the day. Getting the child to go to the toilet just before bed may be helpful. Alarm systems are available that involve the placement of humidity-sensitive pads in the child’s bed. The child is woken by the alarm if urine is passed and eventually learns to wake before urinating.... enuresis
Damage to the language centres of the brain (usually due to a stroke, head injury, or brain tumour) leads to aphasia, which may impair speech.
Disorders of articulation may be caused by damage to nerves that go to muscles in the larynx, mouth or lips, due to stroke, head injury, multiple sclerosis, or Parkinson’s disease. A structural abnormality of the mouth, such as a cleft lip and palate, can also be a cause.
Disorders of voice production include hoarseness and inappropriate pitch or loudness. In many cases, the cause is a disorder affecting closure of the vocal cords (see larynx, disorders of). A voice that is too high or low or too loud or soft may be caused by a hormonal or psychiatric disturbance or by hearing loss.
Disorders of fluency include stuttering, which is marked by hesitant speech and repetition of sounds.
Delayed speech development in a child may be due to hearing loss (see deafness), slow maturation of the nervous system, poor tongue and lip control, lack of stimulation, or emotional disturbance (see developmental delay).
Many people with speech disorders can be helped by speech therapy.... speech disorders
Health Encyclopedia