Glossary Please select an letter from the A-Z list or search # A B C D E F G H I J K L M N O P Q R S T U V W X Y Z B cell A type of immune cell, responsible for making antibodies. bacteraemia The presence of bacteria in the blood. bacteria Single-celled micro-organisms. baseline Starting point or value. basophil A type of white blood cell, also called a granular leukocyte, filled with granules of toxic chemicals, that can digest micro-organisms. Basophils are responsible for some of the symptoms of an allergy. bd Abbreviation of a Latin term meaning twice daily. bias When the estimate from a study differs systematically from the true state of affairs. bid Abbreviation of a Latin term meaning twice daily. bile A fluid produced by the liver. Partly a secretion of waste products and partly aids digestion by breaking down fats and assisting the absorption of nutrients. bilirubin Bilirubin is a substance produced during the normal breakdown of red blood cells. Bilirubin passes through the liver and is excreted in faeces. Elevated levels of bilirubin (jaundice) may indicate liver damage or disease. binary endpoint An endpoint in a trial where there is only one of two options (e.g. yes/no, viral load under or over 50 copies/ml). bioavailability How much of a drug is absorbed into the bloodstream. biopsy A small sample of tissue removed from the body and examined for signs of disease. A liver biopsy is the most reliable way of assessing the extent of liver scarring and inflammation. bloating A sensation that the abdomen (stomach) is full or under pressure, sometimes causing pain. blood-borne virus (BBV) A virus transmitted through contact with infected blood. Hepatitis B, hepatitis C and HIV are BBVs. (Note that hepatitis B and HIV may also be transmitted through other body fluids). blood-brain barrier The name for the body's defence system which makes it hard for many substances in the blood to get into the central nervous system. bone marrow Cells in the middle of bones which are responsible for producing blood cells. breakthrough After dropping to undetectable levels, hepatitis C RNA is detected again in blood during treatment. Different from ‘relapse’. bronchoscopy A medical procedure using a flexible fibre-optic tube that enables examination and biopsy of the lungs.