Cold, Common

-
Common Cold, acute infectious disease of the upper respiratory tract, caused by more than 100 kinds of viruses. The infection affects the mucous membranes of the nose and throat, causing such symptoms as nasal congestion and discharge, sore throat, and coughing. These symptoms are typical also of respiratory infections caused by bacteria, and of allergic conditions such as hay fever and asthma; therefore, the common cold is difficult to diagnose with certainty.

Normally it runs a mild course, without fever, and subsides spontaneously in about seven days. Its medical significance lies in the possible complications that may ensue. Various diseases, such as bronchitis, pneumonia, and sinus or middle-ear infections, may arise from the cold. Research indicates that there are several strains of each type of virus with varying degrees of virulence. Infection with one strain confers only a brief immunity to reinfection by the same strain, and gives no immunity against the other strains. In 1985, United States researchers using advanced X-ray crystallography techniques produced a three-dimensional, atomic scale model of one of the most common cold viruses. Study of the antibody binding sites on the viral coat revealed a very high degree of antigenic variability, suggesting that production of a vaccine to protect people from the common cold may never be practical.

Methods of treating a cold are directed toward the relief of symptoms and the prevention of complications. Bed rest is commonly recommended to avoid complications, even when the cold itself is not incapacitating. Antibiotics are often administered as a preventive measure, but there is no evidence that they are helpful.

related articles:

Comments

Post a Comment

Popular posts from this blog

Cream, Butter, and Ice Cream

-
. In order for a product to be labeled as cream, it must contain 18 percent milk fat or more. Light whipping cream must contain at least 30 percent fat, and 36 percent fat is the minimum fat content for heavy whipping cream. Half-and-half, an equal mixture of both milk and cream, must have at least 10.5 percent fat. The various grades of cream are valued for their smooth, thick texture. They are often used in cooking instead of milk, because they are less likely to form a skin when heated and can be whipped into a stiff foam. When chilled cream is churned gently, the fat globules gather together to form butter, leaving buttermilk as the by-product. Butter contains at least 82.5 percent fat. In the past, before the advent of widespread refrigeration, salt was added to butter to retard bacterial spoilage; now salt is added mainly for flavor. Ice cream, a popular frozen dessert, is made of milk, cream, sugar, and flavoring. The mixture is slowly beaten while chilled until it is partially
Read more

Deoxyribonucleic Acid

-
Deoxyribonucleic Acid (DNA), genetic material of all cellular organisms and most viruses. DNA carries the information needed to direct protein synthesis and replication. Protein synthesis is the production of the proteins needed by the cell or virus for its activities and development. Replication is the process by which DNA copies itself for each descendant cell or virus, passing on the information needed for protein synthesis. In most cellular organisms, DNA is organized on chromosomes located in the nucleus of the cell .
Read more

How HIV Causes Infections

-
HIV transmission occurs when a person is exposed to body fluids infected with the virus, such as blood, semen, vaginal secretions, and breast milk. The primary modes of HIV transmission are (1) sexual relations with an infected person (see Sexually Transmitted Infections ); (2) sharing hypodermic needles or accidental pricking by a needle contaminated with infected blood; and (3) transfer of the virus from an infected mother to her baby during pregnancy, childbirth, or through breast-feeding. When HIV enters the body, it infects lymphocytes, which are a type of white blood cell in the immune system . HIV uses its glycoproteins to attach itself to receptors on the surface of a lymphocyte. The outer envelope of HIV then fuses with the lymphocyte, enabling the HIV capsid to enter the lymphocyte itself. HIV commandeers the genetic material of the lymphocyte, instructing the cell to replicate more viruses. The newly formed viruses break free from the host, destroying the cell in the process
Read more