protein
DEFINITION:
Any of a group of complex organic compounds which contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur, the characteristic element being nitrogen, and which are widely distributed in plants and animals. Proteins, the principal constituents of the protoplasm of all cells, are of high molecular weight and consist essentially of combinations of a-amino acids in peptide linkages. Twenty different amino acids are commonly found in proteins, and each protein has a unique, genetically defined amino acid sequence which determines its specific shape and function. They serve as enzymes, structural elements, hormones, immunoglobulins, etc., and are involved in oxygen transport, muscle contraction, electron transport, and other activities throughout the body, and in photosynthesis.
binding protein - any of a number of plasma proteins (See below) that bind to hormones of low solubility (chiefly the thyroid and steroid hormones), thus providing a transport system for them; some are specific for particular hormones, while others bind to any sparingly soluble hormones. Called also carrier protein or transport protein (See below).
carrier proteins - A binding protein (See above).
plasma proteins - The hundreds of different proteins present in blood plasma, including carrier proteins (such as albumin, transferrin, and haptoglobin), fibrinogen and other coagulation factors, complement components, immunoglobulins, enzyme inhibitors, precursors of substances such as angiotensin and bradykinin, and many other types of proteins.
transport protein - binding protein (See above).
factor
DEFINITION:
1. Any of several substances or activities that are necessary to produce a result, e.g., a coagulation factor (see below). Often, use of the term "factor" indicates that the chemical nature of the substance or its mechanism of action is unknown, as in endocrinology, where "factors" are renamed as "hormones" when their chemical nature is determined.
2. One of two or more quantities that multiplied together form a product.
3. A gene (hereditary factor).
Antihemophilic Factor (AHF) -
1. See Factor VIII under coagulation factor (below).
2. [USP] A sterile freeze-dried powder containing the Factor VIII fraction prepared from units of human venous plasma obtained from suitable whole-blood donors; it may contain heparin sodium or sodium citrate. Used to arrest hemorrhage or to prevent hemorrhage during surgery or other procedures in patients with hemophilia A; administered intravenously.
Coagulation Factors - Substances in the blood that are essential to the clotting process and hence, to the maintenance of normal hemostasis. They are designated by Roman numerals, to which the notation "a" is added to indicate the activated state. Platelet factors (see below), designated by Arabic numerals, also play a role in coagulation.
Coagulation Factor II, prothrombin - A plasma protein that is converted to the active form thrombin (factor IIa) by cleavage by activated factor X (Xa) in the common pathway of blood coagulation; thrombin then cleaves fibrinogen to its active form fibrin. Deficiency of the factor leads to hypoprothrombinemia.
Coagulation Factor III, tissue thromboplastin - A lipoprotein functioning in the extrinsic pathway of blood coagulation, activating factor X (see below).
Coagulation Factor V, proaccelerin - A heat- and storage-labile material, present in plasma but not in serum, functioning in both the intrinsic and extrinsic pathways of blood coagulation. Deficiency of this factor, an autosomal recessive trait, leads to a rare hemorrhagic tendency, known as Owren's disease or parahemophilia, which varies greatly in severity.
Coagulation Factor VIII, antihemophilic factor (AHF) - A relatively storage-labile factor (see below) participating only in the intrinsic pathway of blood coagulation. Deficiency of this factor, when transmitted as a sex-linked recessive trait, causes classical hemophilia (hemophilia A). (See also antihemophilic factor above.)
Coagulation Factor IX, plasma thromboplastin component (PTC) - A relatively storage-stable substance involved in the intrinsic pathway of blood coagulation; upon activation, it activates factor X (see below). Deficiency results in a hemorrhagic syndrome called hemophilia B, resembling hemophilia A. Called also autoprothrombin II, Christmas factor, and antihemophilic factor B.
Coagulation Factor X, Stuart factor - A storage-stable factor that participates in both the intrinsic and extrinsic pathways of blood coagulation, uniting them to begin the common pathway of coagulation. Once activated, it forms a complex with calcium, phospholipid, and factor V (see above); the complex (prothrombinase) can cleave and activate prothrombin to thrombin. Deficiency of this factor may cause a systemic coagulation disorder.
Coagulation Factor XI, plasma thromboplastin antecedent (PTA) - A stable factor involved in the intrinsic pathway of blood coagulation; once activated, it activates factor IX. Deficiency of this factor results in a systemic blood-clotting defect called hemophilia C, which may resemble hemophilia A. Called also antihemophilic factor C.
Coagulation Factor XII, Hageman factor - A stable factor activated by contact with glass or other foreign surfaces, which initiates the intrinsic process of blood coagulation by activating factor XI and participates in activation of the kinin and fibrinolytic pathways. Deficiency of this factor results in a tendency toward thrombotic disorders, due to lack of activation of the fibrinolytic pathway. Called also glass factor, contact factor, or activation factor.
Heat-labile Factor - See Factor V under Coagulation Factors (above).
Platelet Factor - Factors important in hemostasis which are contained in or attached to the platelets.
Storage-labile Factor - A factor which shows chemically-unstable attributes during storage.
von Willebrand Factor (vWF) - The attribute of factor VIII (see above) necessary for the adhesion of platelets to vascular elements. Deficiency of this factor results in the prolonged bleeding time seen in von Willebrand's disease.
proteins
DEFINITION:
Any of a group of complex organic compounds which contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur, the characteristic element being nitrogen, and which are widely distributed in plants and animals. Proteins, the principal constituents of the protoplasm of all cells, are of high molecular weight and consist essentially of combinations of a-amino acids in peptide linkages. Twenty different amino acids are commonly found in proteins, and each protein has a unique, genetically defined amino acid sequence which determines its specific shape and function. They serve as enzymes, structural elements, hormones, immunoglobulins, etc., and are involved in oxygen transport, muscle contraction, electron transport, and other activities throughout the body, and in photosynthesis.
binding protein - any of a number of plasma proteins (See below) that bind to hormones of low solubility (chiefly the thyroid and steroid hormones), thus providing a transport system for them; some are specific for particular hormones, while others bind to any sparingly soluble hormones. Called also carrier protein or transport protein (See below).
carrier proteins - A binding protein (See above).
plasma proteins - The hundreds of different proteins present in blood plasma, including carrier proteins (such as albumin, transferrin, and haptoglobin), fibrinogen and other coagulation factors, complement components, immunoglobulins, enzyme inhibitors, precursors of substances such as angiotensin and bradykinin, and many other types of proteins.
transport protein - binding protein (See above).
renal biopsy
DEFINITION:
A procedure in which a small portion of kidney tissue is removed and examined under a microscope. Renal biopsy is usually performed as part of the investigation and diagnosis of various kidney disorders, such as glomerulonephritis, proteinuria, nephrotic syndrome, or acute renal failure. It may also be used to assess the status of a kidney transplant. Percutaneous (through the skin) needle biopsy of the kidney may not be performed if the person has a bleeding disorder, only one functioning kidney, or chronic renal failure with small, contracted kidneys.
How It Is Done
A percutaneous needle biopsy of the kidney is performed with a local anesthetic injected into the skin and tissues over the kidney; it is virtually painless. There is a risk of bleeding from the kidney into the abdominal cavity.
1. The kidney must be accurately located, usually by an ultrasound scan. Local anesthetic is then injected.
2. A core of tissue is taken by means of a hollow biopsy needle passed through the skin into the kidney.
3. The core of the kidney tissue is embedded in wax and cut into thin slices, which are mounted on slides for staining and microscopic examination.
If a percutaneous needle biopsy is not advisable, an open end renal biopsy may be performed. Using general anesthesia, the surgeon makes a small incision in the flank to visualize the kidney and then cuts a small wedge of renal cortex (the biopsy specimen).
In both cases, the renal tissue is sent to a pathologist for examination under a light microscope, electron microscope, or immunofluorescent microscope.
Recovery Period
The patient may have slight pain in the back for some hours after the biopsy and a small amount of blood may be passed in the urine. Provided there are no complications (such as severe bleeding), the patient can return home the following day.
blood tests
DEFINITION:
Analysis of a sample of blood that gives information on its cells and proteins and any of the chemicals, antigens, antibodies, and gases that it carries. Since blood is the main transport system of the body, such tests can be used to check on the health of major organs, as well as on respiratory function, hormonal balance, the immune system, and metabolism.
Types
There are three types of blood tests.
Hematological Tests: These tests involve looking at the components of the blood itself, examining the numbers, shape, size, and appearance of cells, and testing the function of clotting factors. The most important hematological tests are blood count, blood smear, and blood clotting tests.
Biochemical Tests: These look at chemicals in the blood, such as sodium, potassium, uric acid, and urea, and at vitamins, gases, digested foods, and drugs.
Microbiological Tests: In these tests, the blood is examined for microorganisms, such as bacteria, viruses, and viral particles, fungi, and parasites, and for antibodies that form against them.
How They Are Done
The most convenient site for taking a blood sample is a vein at the bend in the elbow. A tourniquet is applied to the upper arm, and the blood is withdrawn through a needle into a syringe. The procedure causes only mild discomfort. Up to 20 ml of blood may be required, but, as the circulation contains 4 to 5 liters, loss of this small proportion has no harmful effect. If only a few drops are needed, they may be obtained by pricking a finger. Some tests require arterial blood, which is taken from the wrist or the groin. Obtaining such blood is a more difficult procedure that may cause some discomfort.
The sample may be allowed to clot, leaving its clear serum for examination, or an anticoagulant may be added to allow study of the cells and clotting factors. The sample is then sent to the laboratory, where one or more of the hundreds of available tests are performed. In some laboratories, modern computerized analyzers are used to perform many different tests simultaneously on one small sample of blood. The printed results compare each value with the accepted normal range of that test. Each laboratory produces its own normal ranges that depend on the method and the ingredients of the test, and sometimes on the age and sex of the patient.
Used in 3 Article translations
Used in 3 Article translations