Erythrocyte Count: The number of RED BLOOD CELLS per unit volume in a sample of venous BLOOD.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Hematocrit: The volume of packed RED BLOOD CELLS in a blood specimen. The volume is measured by centrifugation in a tube with graduated markings, or with automated blood cell counters. It is an indicator of erythrocyte status in disease. For example, ANEMIA shows a low value; POLYCYTHEMIA, a high value.Hematologic Tests: Tests used in the analysis of the hemic system.Blood Cell Count: The number of LEUKOCYTES and ERYTHROCYTES per unit volume in a sample of venous BLOOD. A complete blood count (CBC) also includes measurement of the HEMOGLOBIN; HEMATOCRIT; and ERYTHROCYTE INDICES.Hemoglobins: The oxygen-carrying proteins of ERYTHROCYTES. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements.Erythrocyte Membrane: The semi-permeable outer structure of a red blood cell. It is known as a red cell 'ghost' after HEMOLYSIS.Leukocyte Count: The number of WHITE BLOOD CELLS per unit volume in venous BLOOD. A differential leukocyte count measures the relative numbers of the different types of white cells.Erythrocyte Aging: The senescence of RED BLOOD CELLS. Lacking the organelles that make protein synthesis possible, the mature erythrocyte is incapable of self-repair, reproduction, and carrying out certain functions performed by other cells. This limits the average life span of an erythrocyte to 120 days.Erythrocyte Deformability: Ability of ERYTHROCYTES to change shape as they pass through narrow spaces, such as the microvasculature.Anion Exchange Protein 1, Erythrocyte: A major integral transmembrane protein of the ERYTHROCYTE MEMBRANE. It is the anion exchanger responsible for electroneutral transporting in CHLORIDE IONS in exchange of BICARBONATE IONS allowing CO2 uptake and transport from tissues to lungs by the red blood cells. Genetic mutations that result in a loss of the protein function have been associated with type 4 HEREDITARY SPHEROCYTOSIS.Hemolysis: The destruction of ERYTHROCYTES by many different causal agents such as antibodies, bacteria, chemicals, temperature, and changes in tonicity.Platelet Count: The number of PLATELETS per unit volume in a sample of venous BLOOD.CD4 Lymphocyte Count: The number of CD4-POSITIVE T-LYMPHOCYTES per unit volume of BLOOD. Determination requires the use of a fluorescence-activated flow cytometer.Erythrocyte Aggregation: The formation of clumps of RED BLOOD CELLS under low or non-flow conditions, resulting from the attraction forces between the red blood cells. The cells adhere to each other in rouleaux aggregates. Slight mechanical force, such as occurs in the circulation, is enough to disperse these aggregates. Stronger or weaker than normal aggregation may result from a variety of effects in the ERYTHROCYTE MEMBRANE or in BLOOD PLASMA. The degree of aggregation is affected by ERYTHROCYTE DEFORMABILITY, erythrocyte membrane sialylation, masking of negative surface charge by plasma proteins, etc. BLOOD VISCOSITY and the ERYTHROCYTE SEDIMENTATION RATE are affected by the amount of erythrocyte aggregation and are parameters used to measure the aggregation.C-Reactive Protein: A plasma protein that circulates in increased amounts during inflammation and after tissue damage.Insulin Resistance: Diminished effectiveness of INSULIN in lowering blood sugar levels: requiring the use of 200 units or more of insulin per day to prevent HYPERGLYCEMIA or KETOSIS.Blood Sedimentation: Measurement of rate of settling of erythrocytes in anticoagulated blood.Metabolic Syndrome X: A cluster of metabolic risk factors for CARDIOVASCULAR DISEASES and TYPE 2 DIABETES MELLITUS. The major components of metabolic syndrome X include excess ABDOMINAL FAT; atherogenic DYSLIPIDEMIA; HYPERTENSION; HYPERGLYCEMIA; INSULIN RESISTANCE; a proinflammatory state; and a prothrombotic (THROMBOSIS) state. (from AHA/NHLBI/ADA Conference Proceedings, Circulation 2004; 109:551-556)Biological Markers: Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.Body Mass Index: An indicator of body density as determined by the relationship of BODY WEIGHT to BODY HEIGHT. BMI=weight (kg)/height squared (m2). BMI correlates with body fat (ADIPOSE TISSUE). Their relationship varies with age and gender. For adults, BMI falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (National Center for Health Statistics, Centers for Disease Control and Prevention)Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Videotape Recording: Recording of visual and sometimes sound signals on magnetic tape.Video Recording: The storing or preserving of video signals for television to be played back later via a transmitter or receiver. Recordings may be made on magnetic tape or discs (VIDEODISC RECORDING).Multimedia: Materials, frequently computer applications, that combine some or all of text, sound, graphics, animation, and video into integrated packages. (Thesaurus of ERIC Descriptors, 1994)Floors and Floorcoverings: The surface of a structure upon which one stands or walks.Designer Drugs: Drugs designed and synthesized, often for illegal street use, by modification of existing drug structures (e.g., amphetamines). Of special interest are MPTP (a reverse ester of meperidine), MDA (3,4-methylenedioxyamphetamine), and MDMA (3,4-methylenedioxymethamphetamine). Many drugs act on the aminergic system, the physiologically active biogenic amines.Hoof and Claw: Highly keratinized processes that are sharp and curved, or flat with pointed margins. They are found especially at the end of the limbs in certain animals.Rubber: A high-molecular-weight polymeric elastomer derived from the milk juice (LATEX) of HEVEA brasiliensis and other trees and plants. It is a substance that can be stretched at room temperature to at least twice its original length and after releasing the stress, retract rapidly, and recover its original dimensions fully.Animal Feed: Foodstuff used especially for domestic and laboratory animals, or livestock.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Meat: The edible portions of any animal used for food including domestic mammals (the major ones being cattle, swine, and sheep) along with poultry, fish, shellfish, and game.Weight Gain: Increase in BODY WEIGHT over existing weight.PubMed: A bibliographic database that includes MEDLINE as its primary subset. It is produced by the National Center for Biotechnology Information (NCBI), part of the NATIONAL LIBRARY OF MEDICINE. PubMed, which is searchable through NLM's Web site, also includes access to additional citations to selected life sciences journals not in MEDLINE, and links to other resources such as the full-text of articles at participating publishers' Web sites, NCBI's molecular biology databases, and PubMed Central.Periodicals as Topic: A publication issued at stated, more or less regular, intervals.BooksAmphibians: VERTEBRATES belonging to the class amphibia such as frogs, toads, newts and salamanders that live in a semiaquatic environment.Publishing: "The business or profession of the commercial production and issuance of literature" (Webster's 3d). It includes the publisher, publication processes, editing and editors. Production may be by conventional printing methods or by electronic publishing.MEDLINE: The premier bibliographic database of the NATIONAL LIBRARY OF MEDICINE. MEDLINE® (MEDLARS Online) is the primary subset of PUBMED and can be searched on NLM's Web site in PubMed or the NLM Gateway. MEDLINE references are indexed with MEDICAL SUBJECT HEADINGS (MeSH).Dry Ice: A solid form of carbon dioxide used as a refrigerant.Specific Gravity: The ratio of the density of a material to the density of some standard material, such as water or air, at a specified temperature.Patents as Topic: Exclusive legal rights or privileges applied to inventions, plants, etc.Vacuum: A space in which the pressure is far below atmospheric pressure so that the remaining gases do not affect processes being carried on in the space.Blood Specimen Collection: The taking of a blood sample to determine its character as a whole, to identify levels of its component cells, chemicals, gases, or other constituents, to perform pathological examination, etc.Gravity Sensing: Process whereby a cell, bodily structure, or organism (animal or plant) receives or detects a gravity stimulus. Gravity sensing plays an important role in the directional growth and development of an organism (GRAVITROPISM).Plasma: The residual portion of BLOOD that is left after removal of BLOOD CELLS by CENTRIFUGATION without prior BLOOD COAGULATION.Adrenal Insufficiency: Conditions in which the production of adrenal CORTICOSTEROIDS falls below the requirement of the body. Adrenal insufficiency can be caused by defects in the ADRENAL GLANDS, the PITUITARY GLAND, or the HYPOTHALAMUS.Aldosterone: A hormone secreted by the ADRENAL CORTEX that regulates electrolyte and water balance by increasing the renal retention of sodium and the excretion of potassium.Adrenal Glands: A pair of glands located at the cranial pole of each of the two KIDNEYS. Each adrenal gland is composed of two distinct endocrine tissues with separate embryonic origins, the ADRENAL CORTEX producing STEROIDS and the ADRENAL MEDULLA producing NEUROTRANSMITTERS.Hydrocortisone: The main glucocorticoid secreted by the ADRENAL CORTEX. Its synthetic counterpart is used, either as an injection or topically, in the treatment of inflammation, allergy, collagen diseases, asthma, adrenocortical deficiency, shock, and some neoplastic conditions.Addison Disease: An adrenal disease characterized by the progressive destruction of the ADRENAL CORTEX, resulting in insufficient production of ALDOSTERONE and HYDROCORTISONE. Clinical symptoms include ANOREXIA; NAUSEA; WEIGHT LOSS; MUSCLE WEAKNESS; and HYPERPIGMENTATION of the SKIN due to increase in circulating levels of ACTH precursor hormone which stimulates MELANOCYTES.Adrenal Gland Diseases: Pathological processes of the ADRENAL GLANDS.Adrenal Cortex: The outer layer of the adrenal gland. It is derived from MESODERM and comprised of three zones (outer ZONA GLOMERULOSA, middle ZONA FASCICULATA, and inner ZONA RETICULARIS) with each producing various steroids preferentially, such as ALDOSTERONE; HYDROCORTISONE; DEHYDROEPIANDROSTERONE; and ANDROSTENEDIONE. Adrenal cortex function is regulated by pituitary ADRENOCORTICOTROPIN.