Common colds

Cooler hot gas temperature high Cooler cold gas temperature high Common cold gas temperature high Machine gas temperature high... 

In this chapter we will examine the construction principles of spherical viruses, the structures of individual subunits and the host cell binding properties of the surface of one of the picornaviruses, the common cold virus. 

Drugs against the common cold may be designed from the structure of rhinovirus... 

Rossmann, M.G., et al. Structure of a human common cold virus and functional relationship to other picor-naviruses. Nature 317 145-153, 1985. 

Bende, M., Barrow, ]., Heptonstall, J., Higgins, P. G., Al-Nakib, W., Tyrrell, D.. 4.. ind Aker lund, A. (1989). Changes in human nasal mucosa during experimental coronaviruH common colds, Acta Otolaryngol. (Utockh) 107, 262-269. 

Eye, nose, and throat irritation dizziness lethargy fever. May act as asthma trigger may transmit humidifier fever influenza, common cold, tuberculosis and other infectious diseases. 

The commercial units have a very low thermal capacity and very high response speeds. Some are available with several independent channels and a common cold junction. Each channel is scanned in turn by the instrument, and the readings either displayed or stored for future recovery. Accuracies of better than 0.2 per cent are possible. Thermocouples are available to cover a very wide range of temperatures, their cost is low and they have a small mass, so minimizing the intrusive effect on the surface at the point where the temperature is being measured. The output characteristics (output voltage versus temperature) are reasonably linear but the measurement accuracy is not particularly high. 

In more recent times, large doses of vitamin C have been claimed to prevent the common cold, cure infertility, delay the onset of symptoms in acquired immunodeficiency syndrome (AIDS), and inhibit the development of gastric and cervical cancers. None of these claims have been backed by medical evidence, however. In the largest study yet done of the effect of vitamin C on the common cojd, a meta-analysis of more than 100 separate trials covering 40,000 people found no difference in the incidence of colds between those who took supplemental vitamin G regularly and those who did not. When taken during a cold, however, vitamin C does appear to decrease the cold s duration by 8%. 

Rhinoviruses, which represent the single major cause of common cold, belong to the family of picornavimses that harbors many medically relevant pathogens. Inhibitors of the 3C protease, a cysteine protease, have shown good antiviral potential. Several classes of compounds were designed based on the known substrate specificity of the enzyme. Mechanism-based, irreversible Michael-acceptors were shown to be both potent inhibitors of the purified enzyme and to have antiviral activity in infected cells. 

Vitamin C status is supposed to play a role in immune function and to influence the progression of some chronic degenerative diseases like atherosclerosis, cancer, cataracts, and osteoporosis. The role of vitamin C in immune function, especially during common cold and upper respiratory tract infection, is the subject of lively debate. The exact mechanisms of action have not yet been fully elucidated, but the results of several trials point to a reduced duration and intensity of infections in subjects consuming high amounts of vitamin C (200-1000 mg/d). However, the incidence of common cold was not influenced significantly (24). 

On the basis of available results, persons suffering from common cold might benefit from taking 1 -2 g/d of vitamin C. However, the usefulness of taking high amounts of vitamin C to prevent common cold has yet to be proven [2]. 

M ore than 200 viruses have been identified as capable of producing disease Acute viruses, such as the common cold, have a rapid onset and quick recovery. Chronic viral infections, such as acquired immunodeficiency syndrome (AIDS), have recurrent episodes of exacerbations (increases in severity of symptoms of the disease) and remissions (periods of partial or complete disappearance of the signs and symptoms). Display 14-1 describes the viruses discussed in this chapter. 

Decongestants are used to treat the congestion associated with rhinitis, hay fever, allergic rhinitis, sinusitis, and the common cold. In addition, they are used in adjunctive therapy of middle ear infections to decrease congestion around the eustachian tube Nasal inhalers may relieve ear block and pressure pain during air travel. Many can be administered orally as well as topically, but topical application is more effective than the oral route. 

Ephedra is used in diet products as an appetite depressant and stimulant, and in sports drinks to mask fatigue. It is also used as a bronchial stimulator, and to relieve symptoms of the common cold. 

Rhinoviruses cause a significant fraction of the common colds suffered by the human population. However, members of the Rhinovirus genus (Picomaviridae family) include 100 different serotypes that infect humans, making a vaccine strategy impractical. Thus, alternative strategies are needed to intervene in these non-life-threatening but inconvenient infections. 

Rhinoviruses Naked icosahedra 30 nm in diameter The common cold viruses there are over 100 antigenioally distinct types, hence the diffiouity in preparing effective vaccines. The virus is shed copiousiy in watery nasai secretions... 

Virus infections such as influenza and the common cold (in reality 300-400 different strains ofrhinovirus) infect epithelial cells ofthe respiratory tract and nasopharynx, respectively. Release ofthe virus, after lysis ofthe host cells, is to the void rather than to subepithelial tissues. The epithelia is further infected resulting in general degeneration ofthe tracts. Such damage predisposes the respiratory tract to infection with opportunistic pathogens such as Neisseria meningitidis and Haemophilus influenzae. 

The intensity of the daily chronic maintenance regimen varies based on patient age, baseline lung function, other organ system involvement, and social factors such as time available for therapy and patient-selected care choices. Generally, with more severe lung disease and multi-organ system involvement, therapies become more complicated and time intensive. Additionally, therapy is intensified when pulmonary symptoms are increased with acute exacerbations or even mild viral upper respiratory illness such as the common cold. The approach to treatment is best described by the organ system affected. 

Rest, fluids, humidified air, and nasal saline are the mainstays of nonpharmacologic therapy for the common cold. Pregnant women experiencing cold symptoms should be advised of these strategies and reminded that cold symptoms typically last only 7 to 10 days. 

Hofer F. Members of the low density lipoprotein receptor family mediate cell entry of a minor group common cold virus. Proc Natl Acad Sci USA 1994 91 1839-1842. 

Rhinoviri are the causal agents of common colds in humans. Viral replication and maturation is dependent on proteolytic processing of a viral polyprotein by a cysteine protease known as 3C protease. The active-site cysteine in 3C protease... 

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