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A disease of the nervous system characterized by a progressive dementia that leads to profound impairment in cognition and behavior. Dementia occurs in a number of brain diseases where the impairment in cognitive abilities represents a decline from…

The capability that a bacterium acquires to counteract an inhibitory chemical molecule or compound that was formerly effective in killing it or preventing its growth. Antibiotic resistance in bacteria (Fig. 1) is a hot topic in the media and in…

Chemical compounds biosynthetically or synthetically produced that destroy or usefully suppress the growth or metabolism of a variety of microscopic or submicroscopic forms of life. On the basis of their primary activity, antimicrobial agents (see…

Any treatment or procedure that includes the in-vitro handling of oocytes (immature ova or egg cells) and sperm or embryos for the purpose of establishing a pregnancy. Assisted reproductive technology (ART) is undertaken as a treatment of…

A genus of pathogenic gram-negative bacteria that are coccobacilli and obligate aerobes, and fail to ferment carbohydrates. Bordetella bacteria are respiratory pathogens. Bordetella pertussis, B. parapertussis, and B. bronchiseptica share greater…

Cells within a tumor that possess the capacity to self-renew and cause the heterogeneous lineages of cancerous cells that comprise the tumor. Cancer stem cells (CSCs) typically represent a small percentage of all cells in a tumor (rarely more than…

The administration of chemical substances for the treatment of disease, especially cancer, or for the prevention of aberrant growth of cells or tissues (neoplasms). In general, chemotherapy is the use of chemicals to treat any disease, but the term…

A genus of bacteria, including a number of important human pathogens, comprising large anaerobic spore-forming rods that usually stain gram-positive. Most species of the genus Clostridium are anaerobes, but a few will grow minimally in air at…

A genome-engineering technique that allows precise targeting of specific stretches of genetic code and editing of DNA at designated locations. The CRISPR/Cas9 system has been used as a general tool to engineer the genomes of many different…

The ability of an organism to resist the action of an inhibitory molecule or compound. Drug resistance is the decreased reactivity of living organisms to the injurious actions of certain drugs and chemicals. Examples of drug resistance include…

An organism that has had its genetic material manipulated or altered in a laboratory setting through the use of genetic or genomic engineering techniques. Genetically modified organisms (GMOs) are microorganisms, plants, or animals that have been…

Pathologies of the heart and its blood vessels. The heart is the muscular pumping organ of the cardiovascular system of vertebrates (Fig. 1). However, a diseased or defective heart can have serious consequences. Almost all cardiovascular or heart…

A type of human cancer cell maintained in tissue culture since 1951, originally excised from the cervical carcinoma of a patient named Henrietta Lacks. The first immortal human cells to grow successfully outside the human body were labeled HeLa…

The study of bacteria that cause human disease. The field of medical bacteriology encompasses the detection and identification of bacterial pathogens (Fig. 1), the determination of the sensitivity and mechanisms of resistance of bacteria to…

A type of skin cancer caused by the uncontrolled proliferation of epidermal melanocytes (cells containing dark pigments). Melanoma (see illustration) is well known for its rapid progression, metastasis, and poor prognosis. Statistics from the United…

An experience of discomfort, primarily associated with tissue damage. Pain involves somesthetic sensations that are generally unpleasant and often cause suffering or distress. Pain (see illustration) is more complex than other sensory systems, such…

An inherited disorder of red blood cells characterized by lifelong anemia and recurrent painful episodes. Sickle cell disease, also termed sickle cell anemia, is a chronic, hereditary hemolytic and thrombotic disease in which hypoxia (oxygen…

A branch of medicine concerned with the effects of exercise and sports on the human body, including treatment of injuries. Sports medicine investigates the functioning and conditioning of the human body during physical activity. It can be divided…

A potentially fatal infectious disease caused by protozoan parasites of the genus Trypanosoma. Trypanosomiasis, or sleeping sickness, is the term used to describe a number of diseases affecting vertebrate animals. The causal agents of…

Two babies born to a mother at one birth. There are two types of twins—monozygotic and dizygotic. Members of a twin pair are called co-twins (Fig. 1). Controversy surrounding the definition of a twin arose with the advent of reproductive…