Famvir

By P. Cronos. Simpson College, Redding California.

Physical factors that increase the rate of absorption are alcohol ingestion and decreased gastric acid secretion 250 mg famvir amex. Increased acid production and food ingestion both decrease the rate of absorption ( 16) discount famvir 250mg with amex. Dimeric secretory IgA accounts for most of the increase in IgA production and serves to bind proteins, forming complexes and thereby decreasing the rate of absorption ( 21). For the macromolecules that do get absorbed as intact antigens approximately 2% ( 19) there is the development of oral tolerance. Tolerance is an immunologic unresponsiveness to a specific antigen, in this case food proteins ( 23). Both the local and systemic immune system appear to play a significant role in the development of oral tolerance ( 22), although the exact mechanisms are not well understood. The processing of antigens by the gut into a nonallergenic or tolerogenic form is important ( 24). This has been reported in studies of mice fed ovalbumin, which is immunogenic when administered parenterally. Within 1 hour after ingestion, a form similar in molecular weight to native ovalbumin was recovered from the serum. This tolerogenic form of ovalbumin induced suppression of cell-mediated responses but not antibody responses to native ovalbumin in recipient mice ( 24). This intestinally processed ovalbumin is distinct from systemic antigen processing ( 24). Mice that were first irradiated were unable to process the ovalbumin into a tolerogenic form. Food hypersensitivity is the result of a loss of or lack of tolerance, the cause of which is likely multifactorial. Until recently some of this immaturity was thought to lead to increased absorption of macromolecules from the gut of infants, but studies now indicate that this is not likely ( 30,31). The importance of local IgA is further supported by the finding of an increase in incidence of food allergy associated with IgA deficiency ( 36). Mast cells that play a significant role in the food allergy reaction also appear to play a role in the maturation of the gut associated with weaning (40), a process affected by the mucosal immune system. This is evidenced by inhibition of small intestinal maturation and decreased numbers of intraepithelial lymphocytes with the addition of cyclosporine A ( 41). It has been noted that there is an increase in systemic antibody production, generally food-specific IgM, and IgG in patients with inflammatory bowel disease and celiac disease ( 36). However, the significance of these antibodies is not known because the patients often tolerate these foods well ( 42,43). Food-specific antibodies are also found in normal individuals, although usually of lower level ( 42). Any disruption of the immunologic or nonimmunologic barriers could alter the handling of antigen and lead to an increased production of systemic antibodies. In individuals with genetic predisposition to atopy, this could lead to IgE production and resultant food hypersensitivity reactions on reexposure ( 45). Many more human studies need to be performed in order to elucidate the mechanisms. The glycoprotein in food is the component that is most implicated in food allergies. Glycoproteins that are allergenic have molecular weights of 10,000 to 67,000 daltons. They are water soluble, predominantly heat stable, and resistant to acid and proteolytic digestion ( 46). Although many foods are potentially antigenic, the vast majority of food allergies involve only a few foods ( 47). The combined results of double-blind placebo-controlled food challenges performed in the United States (primarily in children) showed that eight foods were responsible for 93% of reactions (39). The prevalence of specific allergens may vary for different countries, depending on exposure patterns. Allergens found commonly in children but not in adults (eggs, soy, milk and wheat) are usually outgrown with strict elimination for 1 or more years (48), although evidence of IgE antibodies may persist ( 49). Those with histories of severe reactions may take longer to develop clinical tolerance, up to several years (48,50). The others [peanuts ( 51), tree nuts, crustacea (52), and fish (53)] tend to be lifelong and thus are common to both populations. Some whey proteins found in milk are denatured by heating and routine processing, whereas others are rendered more allergenic (54).

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An asthma classification system Allergic Asthma Allergic asthma is caused by inhalation of allergen that interacts with IgE present in high-affinity receptors on bronchial mucosal mast cells purchase 250 mg famvir amex. Allergic asthma often occurs from ages 4 to 40 years but has been recognized in the geriatric population ( 159) and in adult patients attending a pulmonary clinic for care ( 160) discount famvir 250 mg on line. Some physicians believe that many patients with asthma must have some type of allergic asthma because of elevated total serum IgE concentrations ( 161), antiallergen IgE (162) and the frequent finding of peripheral blood or sputum eosinophilia. The use of the term allergic asthma implies that a temporal relationship exists between respiratory symptoms and allergen exposure and that antiallergen IgE antibodies can be demonstrated or suspected. Respiratory symptoms may develop within minutes or in an hour after allergen exposure or may not be obvious when there is uninterrupted allergen exposure. IgE-mediated occupational asthma is considered under the category of occupational asthma. Allergen particle size must be less than 10 m to penetrate into deeper parts of the lung because larger particles, such as ragweed pollen (19 m), impact in the oropharynx. However, submicronic ragweed particles have been described that could reach smaller airways ( 163). Fungal spores, such as Aspergillus species, are 2 to 3 m in size, and the major cat allergen (Fel d 1) has allergenic activity from 0. Another study demonstrated that 75% of Fel d 1 was present in particles of at least 5 m and that 25% of Fel d 1 was present in particles of less than 2. Cat dander allergen can be present in indoor air, on clothes, and in schoolrooms where no cats are present ( 166). The potential severity of allergic asthma should not be minimized because experimentally, after an antigen-induced early bronchial response, bronchial hyperresponsiveness to an agonist such as methacholine or histamine can be demonstrated. In addition, fungus-related (mold-related) asthma may result in a need for intensive antiasthma pharmacotherapy, including inhaled corticosteroids and even alternate-day prednisone in some patients. In children undergoing long-term evaluation for development of atopic conditions who have one parent with asthma or allergic rhinitis, asthma by age 11 years was associated with exposure to high concentrations of Dermatophagoides pteronyssinus, a major mite allergen (169). Similar results seem likely when children of atopic parents are exposed to animals in the house. The diagnosis of allergic asthma should be suspected when symptoms and signs of asthma correlate closely with local patterns of pollinosis and fungal spore recoveries. For example, in the upper midwestern United States after a hard freeze in late November, which reduces (but does not eliminate entirely) fungal spore recoveries from outdoor air, patients suffering from mold-related asthma note a reduction in symptoms and medication requirements. Cockroach allergen ( Bla g 1) is an important cause of asthma in infected buildings, usually in low socioeconomic areas. High indoor concentrations of mouse urine protein (Mus d 1) have been identified with volumetric sampling, and monoclonal antibodies directed at specific proteins suggested additional indoor allergens. The physician should correlate symptoms with allergen exposures, support the diagnosis by demonstration of antiallergen IgE antibodies, and institute measures when applicable to decrease allergen exposure. Some recommendations for environmental control have been made ( 170,171), but these may not be practical to implement for many patients and their families. Detection of cat allergen ( Fel d 1) in homes or schools never known to have cat exposure is consistent with transport of Fel d 1 into such premises and sensitivity of immunoassays for cat allergen. The removal of an animal from a home and covering a mattress and pillow properly are interventions known to decrease the concentration of allergen below which many patients do not have clinical asthma symptoms. Although food ingestion can result in anaphylaxis, persistent asthma is not explained by food ingestion with IgE-mediated reactions. Nonallergic Asthma In nonallergic asthma, IgE-mediated airway reactions to common allergens are not present. Nonallergic asthma occurs at any age range, as does allergic asthma, but the former is generally more likely to occur in subjects with asthma younger than 4 years of age or older than 60 years of age. Episodes of nonallergic asthma are triggered by ongoing inflammation or by upper respiratory tract infections, purulent rhinitis, or sinusitis. In some patients, skin tests are positive, but despite the presence of IgE antibodies, there is no temporal relationship between exposure and symptoms. Often, but not exclusively, the onset of asthma occurs in the setting of a viral upper respiratory tract infection. Virus infections have been associated with mediator release and bronchial epithelial shedding, which could lead to ongoing inflammation and asthma symptoms. Chronic sinusitis can be identified in some patients with asthma, as can nasal polyps with or without aspirin sensitivity. Some experimental data exist on the presence of antiviral IgE antibodies and asthma ( 176). As our knowledge of mast cell activation grows, antiviral IgE antibodies or viral infection of lymphocytes causing cytokine production with triggering of asthma may be considered nonallergic. Indeed, the T H2 theory of asthma was supported in part by a study finding that protection against developing asthma in children aged 6 to 13 years was associated with day care attendance during the first 6 months of life or with having two or more older siblings at home ( 177).

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To the hand that wielded the sword was attributed the power to subdue not only the enemy but also the spirit buy discount famvir 250 mg. Up to the eighteenth century the king of England laid his hands every year upon those afflicted with facial tuberculosis whom physicians knew they were unable to cure generic 250 mg famvir visa. Today the medical establishment is about to reclaim the right to perform miracles. Medicine claims the patient even when the etiology is uncertain, the prognosis unfavorable, and the therapy of an experimental nature. Under these circumstances the attempt at a "medical miracle" can be a hedge against failure, since miracles may only be hoped for and cannot, by definition, be expected. The radical monopoly over health care that the contemporary physician claims now forces him to reassume priestly and royal functions that his ancestors gave up when they became specialized as technical healers. The medicalization of the miracle provides further insight into the social function of terminal care. The patient is strapped down and controlled like a spaceman and then displayed on television. These heroic performances serve as a rain-dance for millions, a liturgy in which realistic hopes for autonomous life are transmuted into the delusion that doctors will deliver health from outer space. By dumping, the medical lords divest themselves of the nuisance of low-prestige care and invest policemen, teachers, or personnel officers with a derivative medical fiefdom. Medicine retains unchecked autonomy in defining what constitutes sickness, but drops on others the task of ferreting out the sick and providing for their treatment. Only medicine knows what constitutes addiction, though policemen are supposed to know how it should be controlled. Only medicine can define brain damage, but it allows teachers to stigmatize and manage the healthy-looking cripples. When the need for a retrenchment of medical goals is discussed in medical literature, it now usually takes the shape of planned patient-dumping. People who look strange or who behave oddly are subversive until their common traits have been formally named and their startling behavior slotted into a recognized pigeonhole. The agent who does this labeling does not necessarily have to be comparable to medical authority: he may hold juridical, religious, or military power. By naming the spirit that underlies deviance, authority places the deviant under the control of language and custom and turns him from a threat into a support of the social system. Etiology is socially self-fulfilling: if the sacred disease is believed to be caused by divine possession, then the god speaks in the epileptic fit. To postulate for every society a specifically "sick" kind of deviance with even minimal common characteristics252 is a hazardous undertaking. It developed not much more than a generation before Henderson and Parsons analyzed it. When he assigns sick-status to a client, the contemporary physician might indeed be acting in some ways similar to the sorcerer or the elder; but in belonging also to a scientific profession that invents the categories it assigns when consulting, the modern physician is totally unlike the healer. Medicine men engaged in the occupation of curing and exercised the art of distinguishing evil spirits from each other. Enabling professions in their annual assemblies create the sick-roles they assign. The roles available for an individual have always been of two kinds: those which are standardized by cultural tradition and those which are the result of bureaucratic organization. Innovation at all times meant a relative increase of the latter, rationally created roles. But on the whole, the sick-role tended until recently to be of the traditional kind. The physician has increasingly abandoned his role as moralist and assumed that of enlightened scientific entrepreneur. To exonerate the sick from accountability for their illness has become a predominant task, and new scientific categories of disease have been shaped for the purpose. Medical school and clinic provide the doctor with the atmosphere in which disease, in his eyes, may become a task for biological or social technique; his patients still carry their religious and cosmic interpretations into the ward, much as the laymen once carried their secular concerns into church for Sunday service. Expert selection of a few for institutional pampering was a way to use medicine for the purpose of stabilizing an industrial society:258 it entailed the easily regulated entitlement of the abnormal to abnormal levels of public funds. Kept within limits, during the early twentieth century the pampering of deviants "strengthened" the cohesion of industrial society. But after a critical point social control exercised through the diagnosis of unlimited needs destroyed its own base. The doctor deals with clients who are simultaneously cast in several roles during every contact they have with the health establishment. They are turned into patients whom medicine tests and repairs, into administered citizens whose healthy behavior a medical bureaucracy guides, and into guinea pigs on whom medical science constantly experiments. The Aesculapian power of conferring the sick-role has been dissolved by the pretensions of delivering totalitarian health care. Health has ceased to be a native endowment each human being is presumed to possess until proven ill, and has become an ever-receding goal to which one is entitled by virtue of social justice.

Famvir
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