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The enzyme that breaks down milk sugar (lactose).


A type of sugar found in milk and dairy products.


An abnormal change in structure of an organ or body part due to injury or disease.


Involves removal of blood to collect specific blood cells.


The medication most commonly used to treat Parkinson's symptoms.

Li-Fraumeni syndrome

This is a hereditary cancer predisposition syndrome reported in 1969 by Drs. Frederick Li and Joseph Fraumeni from the National Cancer Institute.


The tough bands of tissue that serve to connect the articular extremities of bones or to support or keep an organ in place. Ligaments are usually composed of coarse bundles of dense white fibrous tissue parallel or closely interlaced - they are pliant and flexible, but not extensible.

Liver cancer

The growth and spread of unhealthy cells in the liver. Also known as hepatocellular carcinoma.

Liver failure

Liver failure is the inability of the liver to function.

Liver transplant

A liver transplant is the process of replacing a diseased liver with a donated, healthy liver.


A chronic, autoimmune disease that can damage any part of the body (skin, joints, and/or organs inside the body).

Lupus-like reaction

A reaction that looks like Lupus, defined as an inflammatory connective tissue disease often held to be an autoimmune disease. Occurring chiefly in women, Lupus is characterized by fever, skin rash and arthritis, often by acute hemolytic anemia, and by small hemorrhages in the skin and mucous membranes.

Lyme disease

A bacterial infection that can occur from the bite of an infected tick. The first symptom is generally a rash, which may look like a bull's eye.

Lymph node

A lymph node is a rounded mass of lymphatic tissue surrounded by a capsule of connective tissue. Located in the lymphatic system, these nodes filter lymph (lymphatic fluid), and they store white blood cells. Lymph is a clear fluid that carries cells that help fight infections and other diseases. The lymphatic system is made up of the tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases. Lymphatic vessels extend to all tissues of the body.

Lymph nodes

Small bean-shaped structures that are part of the body’s immune system. Lymph nodes filter substances that travel through the lymphatic fluid, and they contain lymphocytes (white blood cells) that help the body fight infection and disease.


A type of immune cell made in the bone marrow and is found in the blood and in lymph tissue. A lymphocyte is a type of white blood cell.


A cancer of a part of the immune system known as the lymph system.