Actinomycetes are microorganisms that are closely related to bacteria. Abundant in soil, compost, fresh water, and other compounds, they are the source of antibiotics, vitamins, and enzymes. Actinomycetes are now known to be an important source of the anti­gens responsible for hypersensitivity pneumonitis, or allergic alveoli­tis, an immunological disease of the lungs. Some examples of hyper­sensitivity pneumonitis are farmer’s lung, bagassosis, bird fancier’s disease, and humidifier lung.

Until the last few years, food additives were considered safe, or at least insignificant in normal doses. Today, such additives are suspected of being responsible for reactions similar to those attributed to food allergy. Additives are synthetic chemicals that add color, taste, and texture to such foods as candies, gelatin desserts, mustard, and canned goods. Unfortunately, because some additives are used so widely and labeled inaccurately, it is often difficult to avoid them. A reaction to food ad ditives is probably not caused by allergies, h rather by a toxic reaction to some substance in the additive. С It is sometimes claimed that food additives are responsible for some psychoneurotic and hyperactive behavior in children.) Hives, asthma rhinitis, and constipation are a few of the possible reactions to additives that may seem to be caused (as they often are) by a food allergy. What is the most effective treatment of food allergy? Once the offending foods have been discovered, the most effective treatment is simply to eliminate them from the diet.

Sensitivity to milk and other foods is not uncommon in children, and the sensitivity does tend to be outgrown. Although there is a good chance that a sensitivity will diminish in time, physicians have no way of knowing for sure whether a sensitivity will persist. When I weaned my son from breast milk and began feeding him cow’s milk, he began to have digestive problems. I stopped the cow’s milk, but now I am worrying about replacing the vitamins and min­erals he would normally get from that milk. What should I do? A number of substitutes for cow’s milk are available, including meat-base and soy-milk formulas. Your physician should be able to prescribe one. If the child shows signs of other allergies, an allergist can advise you on the necessary medication and treatment.

Two conditions constitute an emergency in this category—laryngeal edema and asthma. Swelling of the windpipe, or laryngeal edema, is the most immediately life-threatening. The victim literally feels a lump in the throat, followed by a sensation of constriction and difficulty absorb­ing air, and produces a high-pitched, crowing sound. In other areas of the body, this swelling may be accompanied by hives or edema, or, as mentioned, it may be a manifestation of anaphylaxis. Such drugs as penicillin and its derivatives, and such foods as nuts and shellfish, are among the more common allergic causes. Insect stings, especially on the neck or face, may also be responsible. Variant Diagnosis Anything that can block the windpipe can cause similar symptoms. This includes foreign bodies that enter the respiratory tract instead of the esophagus, infections that cause in­flammation in the throat or the larynx, and tumors in these areas. An asthma attack that is not relieved eventually becomes an emergency. A person with asthma cannot circulate air normally through the bronchial tubes. As these tubes become more con­stricted —due to contraction of their interlacing mutfcle, edema of their inner lining, or excess local production of mucus, among other factors—-the asthma victim works harder and harder to breathe. The initial wheezing becomes louder, exhalation lasts longer, air is trapped inside, and the chest wall expands. The patient is forced to sit up with shoulders hunched forward. It becomes difficult to cough up the thickened mucus, and breathing becomes more and more labored. The symptoms of a serious asthma attack are: 1. An attack that does not improve after several hours have passed. 2. Wheezing that becomes louder and then stops, despite extremely labored breathing. 3. Increasing fatigue and weakness. 4. Pulse rate greater than 160 beats per minute in children under six, greater than 140 in others; or irregular rhythm. 5. Bulging of the neck muscles, an expanded chest cage, and deepening of the notch over the breastbone. Fever is not a prominent factor in any of the emergency situations described thus far. If the asthma is complicated by an infection, the temperature usually exceeds 100°F(39°C). Asthma also may be provoked by a viral respiratory infection such as influenza, in which case the patient suffers from both condi­tions. Asthma may also lead to pneumonia, a condition that may arise in a lung deprived of its normal oxygen supply by bronchial tubes obstructed by mucous plugs. In some cases, a relatively com­mon airborne fungus spore grows in the air passages. An allergic reaction to the fungus produces inflammation that, in turn, causes a febrile bronchitis, or pneumonia. In medicine, this fungus is called aspergillus, and the complication, allergic bronchopulmonary asper­gillosis. If coughing is violent and prolonged, the opposing forces of chest muscles and rib muscles can cause a rib to fracture. Usually the rib does not break sufficiently to puncture the lungs, but the fractured rib can cause sharp chest pain. Coughing can also rupture air sacs in the lungs. The escaping air moves upward under the heart lining and the lung tissues. Trapped air causes a dull pain in the chest, or a sharp pain if part of a lung collapses under the pressure of trapped air (a condition known as pneumothorax). Often the air simply rises under the linings of the bronchial tubes to the trachea and stops in spaces beneath the soft neck tissues. The neck area will bulge and feel like crinkling paper to the touch (subcutaneous emphysema). This outcome —in reality, a safety mechanism—will be resolved and thereafter need not be considered a danger. Variant Diagnosis Wheezing may also result from foreign objects or tumors in the bronchial tubes; infections in the tubes, called in­fectious bronchitis; chemical irritants entering the tubes, such as smoke, lyes, noxious gases; or fluid entering the tubes. Fluid may enter the lungs when a person is drowning, or it may originate internally because of damage to the blood vessels of the lungs. Prominent causes are congestive heart failure or pulmonary edema due to a failing heart, long-diseased lung tissue, and drugs such as heroin.

Because we know that psychology plays an important role in physi­cal health, techniques designed to teach patients to cope psychologi­cally with asthma can and should be employed. These techniques may be learned in an environment specially suited to individual therapy, or they may be taught in a group-therapy environment. Either way, the therapy usually centers on the alteration of asthma-related, inap­propriate behavior and adherence to a program of medication. Some patients must be taught to avoid breathing too fast (hyperventilation), since hyperventilation itself can provoke an asthma attack. Unfor­tunately, there are no standardized approaches to the treatment of asthmatics; therefore, individualized therapy must be employed, be­cause of the differences in individuals and the different forms symp­toms may take. Therapeutic Agents

The pituitary gland is a small oval endocrine glai at the base of the brain; it secretes several hormones, one of whi regulates the secretion of cortisone by the adrenal gland. See al cortisone.

Eosinophils are a type of white blood cell often found in greater numbers in the blood of patients with allergic diseases, as well as in the tissues of people who have had allergic reactions. Little is known about this type of cell, however. What is known about eosinophils is: they are attracted by a chemical released during an allergic reaction; they contain substances capable of neutralizing histamine and related chemical mediators, they probably play a role in regulating these reactions; because they contain a substance that is capable of damaging tissue.

See Asthma, Mixed.

The most common side effects of aerosol steroid preparations are dry mouth and hoarseness, which usually disappear promptly when the drug is discontinued. The major side effects are fungal infections (called Candida albicans or Asper­gillus niger) of the mouth, the pharynx (upper air passages), or occa­sionally the larynx (voice box). These effects often can be prevented by rinsing the mouth with water each time the medication is taken. Discontinuing the aerosol or treating the infection with an antifungal drug nearly always relieves the condition. On rare occasions, rashes occur, and cataracts have been reported but are considered rare. Replacing prednisone or other orally administered corticosteroids with aerosol corticosteroids whenever possible is an effective way to reduce the side effects of the former. The adrenal glands, however, stop producing natural hormones during treatment with oral corti­costeroids. This effect, called adrenal suppression, does not subside for months after all external sources of corticosteroids (those admin­istered orally, by injection, or, to a lesser extent, by inhalation into the lungs, spraying into the nose, or application to the skin) have been removed. Although the adrenal hormones (to which corticos­teroids are related chemically) are harmful in large doses over long periods, they are necessary in small amounts for many body functions. For some functions, the body may be without an adequate supply of adrenal hormones between the time oral corticosteroids are discon­tinued and the time the adrenal glands resume normal production. This inadequacy —called adrenal insufficiency—is a major concern when aerosol corticosteroids replace oral corticosteroids.

In respiratory diseases, sputum is the discharge from air passages; it contains mucus and sometimes pus, bacteria, and other matter.