An automated analyser is a medical laboratory instrument designed to measure different chemicals and other characteristics in a number of biological samples with minimal human assistance. These measured properties of blood and other fluids may be useful in the diagnosis of disease. Many methods of introducing samples into the analyser have been invented; this can involve placing test tubes of sample into racks, which can be moved along a track, or inserting tubes into circular carousels that rotate to make the sample available. Some analysers require samples to be transferred to sample cups. However, the effort to protect the health and safety of laboratory staff has prompted many manufacturers to develop analysers that feature closed tube sampling, preventing workers from direct exposure to samples. Samples can be processed singly, in batches, or continuously; the automation of laboratory testing does not remove the need for human expertise, but it does ease concerns about error reduction, staffing concerns, safety.
These are machines that process a large portion of the samples going into a hospital or private medical laboratory. Automation of the testing process has reduced testing time for many analytes from days to minutes; the history of discrete sample analysis for the clinical laboratory began with the introduction of the "Robot Chemist" invented by Hans Baruch and introduced commercially in 1959. An AutoAnalyzer is an example of an automated chemistry analyzer using a special flow technique named "continuous flow analysis", invented in 1957 by Leonard Skeggs, PhD and first made by the Technicon Corporation; the first applications were for clinical analysis. The AutoAnalyzer profoundly changed the character of the chemical testing laboratory by allowing significant increases in the numbers of samples that could be processed; the design based on separating a continuously flowing stream with air bubbles reduced slow and error prone manual methods of analysis. The types of tests include enzyme levels, ion levels (e.g. sodium and potassium, other tell-tale chemicals.
Simple ions are measured with ion selective electrodes, which let one type of ion through, measure voltage differences. Enzymes may be measured by the rate. Other tests use colorimetric changes to determine the concentration of the chemical in question. Turbidity may be measured. Antibodies are used by some analysers to detect many substances by immunoassay and other reactions that employ the use of antibody-antigen reactions; when concentration of these compounds is too low to cause a measurable increase in turbidity when bound to antibody, more specialised methods must be used. Recent developments include automation for the immunohaematology lab known as transfusion medicine; these are used to perform complete blood counts, erythrocyte sedimentation rates, or coagulation tests. Automated cell counters sample the blood, quantify and describe cell populations using both electrical and optical techniques. Electrical analysis involves passing a dilute solution of the blood through an aperture across which an electrical current is flowing.
The passage of cells through the current changes the impedance between the terminals. A lytic reagent is added to the blood solution to selectively lyse the red cells, leaving only white cells, platelets intact; the solution is passed through a second detector. This allows the counts of RBCs, WBCs, platelets to be obtained; the platelet count is separated from the WBC count by the smaller impedance spikes they produce in the detector due to their lower cell volumes. Optical detection may be utilised to gain a differential count of the populations of white cell types. A dilute suspension of cells is passed through a flow cell, which passes cells one at a time through a capillary tube past a laser beam; the reflectance and scattering of light from each cell is analysed by sophisticated software giving a numerical representation of the overall distribution of cell populations. Some of the latest hematology instruments may report Cell Population Data that consist in Leukocyte morphological information that may be used for flagging Cell abnormalities that trigger the suspect of some diseases.
Reticulocyte counts can now be performed by many analysers, giving an alternative to time-consuming manual counts. Many automated reticulocyte counts, like their manual counterparts, employ the use of a supravital dye such as new methylene blue to stain the red cells containing reticulin prior to counting; some analysers have a modular slide maker, able to both produce a blood film of consistent quality and stain the film, reviewed by a medical laboratory professional. Automated coagulation machines or Coagulometers measure the ability of blood to clot by performing any of several types of tests including Partial thromboplastin times, Prothrombin times, Lupus anticoagulant screens, D dimer assays, factor assays. Coagulometers require blood samples that have been drawn in tubes containing sodium citrate as an anticoagulant; these are used because the mechanism behind the anticoagulant effect of sodium citrate is reversible. Depending on the test, different substances can be added to the blood plasma to trigger a clotting reaction.
The progress of clotting may be monitored optically by measuri
Chemistry is the scientific discipline involved with elements and compounds composed of atoms and ions: their composition, properties and the changes they undergo during a reaction with other substances. In the scope of its subject, chemistry occupies an intermediate position between physics and biology, it is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant chemistry, the formation of igneous rocks, how atmospheric ozone is formed and how environmental pollutants are degraded, the properties of the soil on the moon, how medications work, how to collect DNA evidence at a crime scene. Chemistry addresses topics such as how atoms and molecules interact via chemical bonds to form new chemical compounds. There are four types of chemical bonds: covalent bonds, in which compounds share one or more electron; the word chemistry comes from alchemy, which referred to an earlier set of practices that encompassed elements of chemistry, philosophy, astronomy and medicine.
It is seen as linked to the quest to turn lead or another common starting material into gold, though in ancient times the study encompassed many of the questions of modern chemistry being defined as the study of the composition of waters, growth, disembodying, drawing the spirits from bodies and bonding the spirits within bodies by the early 4th century Greek-Egyptian alchemist Zosimos. An alchemist was called a'chemist' in popular speech, the suffix "-ry" was added to this to describe the art of the chemist as "chemistry"; the modern word alchemy in turn is derived from the Arabic word al-kīmīā. In origin, the term is borrowed from the Greek χημία or χημεία; this may have Egyptian origins since al-kīmīā is derived from the Greek χημία, in turn derived from the word Kemet, the ancient name of Egypt in the Egyptian language. Alternately, al-kīmīā may derive from χημεία, meaning "cast together"; the current model of atomic structure is the quantum mechanical model. Traditional chemistry starts with the study of elementary particles, molecules, metals and other aggregates of matter.
This matter can be studied in isolation or in combination. The interactions and transformations that are studied in chemistry are the result of interactions between atoms, leading to rearrangements of the chemical bonds which hold atoms together; such behaviors are studied in a chemistry laboratory. The chemistry laboratory stereotypically uses various forms of laboratory glassware; however glassware is not central to chemistry, a great deal of experimental chemistry is done without it. A chemical reaction is a transformation of some substances into one or more different substances; the basis of such a chemical transformation is the rearrangement of electrons in the chemical bonds between atoms. It can be symbolically depicted through a chemical equation, which involves atoms as subjects; the number of atoms on the left and the right in the equation for a chemical transformation is equal. The type of chemical reactions a substance may undergo and the energy changes that may accompany it are constrained by certain basic rules, known as chemical laws.
Energy and entropy considerations are invariably important in all chemical studies. Chemical substances are classified in terms of their structure, phase, as well as their chemical compositions, they can be analyzed using the tools of e.g. spectroscopy and chromatography. Scientists engaged in chemical research are known as chemists. Most chemists specialize in one or more sub-disciplines. Several concepts are essential for the study of chemistry; the particles that make up matter have rest mass as well – not all particles have rest mass, such as the photon. Matter can be a mixture of substances; the atom is the basic unit of chemistry. It consists of a dense core called the atomic nucleus surrounded by a space occupied by an electron cloud; the nucleus is made up of positively charged protons and uncharged neutrons, while the electron cloud consists of negatively charged electrons which orbit the nucleus. In a neutral atom, the negatively charged electrons balance out the positive charge of the protons.
The nucleus is dense. The atom is the smallest entity that can be envisaged to retain the chemical properties of the element, such as electronegativity, ionization potential, preferred oxidation state, coordination number, preferred types of bonds to form. A chemical element is a pure substance, composed of a single type of atom, characterized by its particular number of protons in the nuclei of its atoms, known as the atomic number and represented by the symbol Z; the mass number is the sum of the number of neutrons in a nucleus. Although all the nuclei of all atoms belonging to one element will have the same
Laboratory quality control
Laboratory quality control is designed to detect and correct deficiencies in a laboratory's internal analytical process prior to the release of patient results, in order to improve the quality of the results reported by the laboratory. Quality control is a measure of precision, or how well the measurement system reproduces the same result over time and under varying operating conditions. Laboratory quality control material is run at the beginning of each shift, after an instrument is serviced, when reagent lots are changed, after calibration, whenever patient results seem inappropriate. Quality control material should approximate the same matrix as patient specimens, taking into account properties such as viscosity, turbidity and color, it should be simple to use, with minimal vial to vial variability, because variability could be misinterpreted as systematic error in the method or instrument. It should be stable for long periods of time, available in large enough quantities for a single batch to last at least one year.
Liquid controls are more convenient than lyophilized controls because they do not have to be reconstituted minimizing pipetting error. Interpretation of quality control data involves both statistical methods. Quality control data is most visualized using a Levey-Jennings chart; the dates of analyses are plotted along the X-axis and control values are plotted on the Y-axis. The mean and one and three standard deviation limits are marked on the Y-axis. Inspecting the pattern of plotted points provides a simple way to detect increased random error and shifts or trends in calibration; the control charts: a statistical approach to the study of manufacturing process variation for the purpose of improving the economic effectiveness of the process. These methods are based on continuous monitoring of process variation; the control chart known as the'Shewhart chart' or'process-behavior chart' is a statistical tool intended to assess the nature of variation in a process and to facilitate forecasting and management.
A control chart is a more specific kind of a run chart. The control chart is one of the seven basic tools of quality control which include the histogram, pareto chart, check sheet, control chart and effect diagram and scatter diagram. Control charts prevents unnecessary process adjustments. Levey-Jennings chart is a graph that quality control data is plotted on to give a visual indication whether a laboratory test is working well; the distance from the mean is measured in standard deviations. It is named after S. Levey and E. R. Jennings who in 1950 suggested the use of Shewhart's individuals control chart in the clinical laboratory. On the x-axis the date and time, or more the number of the control run, are plotted. A mark is made indicating. Lines run across the graph at the mean, as well as one and three standard deviations to either side of the mean; this makes it easy to see. Rules, such as the Westgard rules can be applied to see whether the results from the samples when the control was done can be released, or if they need to be rerun.
The formulation of Westgard rules were based on statistical methods. Westgard rules are used to analyse data in Shewhart control charts. Westgard rules are used to define specific performance limits for a particular assay and can be used to detect both random and systematic errors. Westgard rules are programmed in to automated analyzers to determine when an analytical run should be rejected; these rules need to be applied so that true errors are detected while false rejections are minimized. The rules applied to high volume chemistry and hematology instruments should produce low false rejection rates; the Levey-Jennings chart differs from the Shewhart individuals control chart in the way that sigma, the standard deviation, is estimated. The Levey-Jennings chart uses the long-term estimate of sigma whereas the Shewhart chart uses the short-term estimate. Quality control Quality assurance Quality assessment www. Westgard.com
Cerebrospinal fluid is a clear, colorless body fluid found in the brain and spinal cord. It is produced by the specialised ependymal cells in the choroid plexuses of the ventricles of the brain, absorbed in the arachnoid granulations. There is about 125mL of CSF at any one time, about 500 mL is generated every day. CSF acts as a cushion or buffer for the brain, providing basic mechanical and immunological protection to the brain inside the skull. CSF serves a vital function in cerebral autoregulation of cerebral blood flow. CSF occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord, it fills the ventricles of the brain and sulci, as well as the central canal of the spinal cord. There is a connection from the subarachnoid space to the bony labyrinth of the inner ear via the perilymphatic duct where the perilymph is continuous with the cerebrospinal fluid. A sample of CSF can be taken via lumbar puncture; this can reveal the intracranial pressure, as well as indicate diseases including infections of the brain or its surrounding meninges.
Although noted by Hippocrates, it was only in the 18th century that Emanuel Swedenborg is credited with its rediscovery, as late as 1914 that Harvey W. Cushing demonstrated CSF was secreted by the choroid plexus. There is about 125–150 mL of CSF at any one time; this CSF circulates within the ventricular system of the brain. The ventricles are a series of cavities filled with CSF; the majority of CSF is produced from within the two lateral ventricles. From here, CSF passes through the interventricular foramina to the third ventricle the cerebral aqueduct to the fourth ventricle. From the fourth ventricle, the fluid passes into the subarachnoid space through four openings – the central canal of the spinal cord, the median aperture, the two lateral apertures. CSF is present within the subarachnoid space, which covers the brain, spinal cord, stretches below the end of the spinal cord to the sacrum. There is a connection from the subarachnoid space to the bony labyrinth of the inner ear making the cerebrospinal fluid continuous with the perilymph in 93% of people.
CSF moves in a single outward direction from the ventricles, but multidirectionally in the subarachnoid space. Fluid movement is pulsatile, matching the pressure waves generated in blood vessels by the beating of the heart; some authors dispute this, posing that there is no unidirectional CSF circulation, but cardiac cycle-dependent bi-directional systolic-diastolic to-and-fro cranio-spinal CSF movements. CSF is derived from blood plasma and is similar to it, except that CSF is nearly protein-free compared with plasma and has some different electrolyte levels. Due to the way it is produced, CSF has a higher chloride level than plasma, an equivalent sodium level. CSF contains 0.3% plasma proteins, or 15 to 40 mg/dL, depending on sampling site. In general, globular proteins and albumin are in lower concentration in ventricular CSF compared to lumbar or cisternal fluid; this continuous flow into the venous system dilutes the concentration of larger, lipid-insoluble molecules penetrating the brain and CSF.
CSF is free of red blood cells, at most contains only a few white blood cells. Any white blood cell count higher. At around the third week of development, the embryo is a three-layered disc, covered with ectoderm and endoderm. A tube-like formation develops in the midline, called the notochord; the notochord releases extracellular molecules that affect the transformation of the overlying ectoderm into nervous tissue. The neural tube, forming from the ectoderm, contains CSF prior to the development of the choroid plexuses; the open neuropores of the neural tube close after the first month of development, CSF pressure increases. As the brain develops, by the fourth week of embryological development three swellings have formed within the embryo around the canal, near where the head will develop; these swellings represent different components of the central nervous system: the prosencephalon and rhombencephalon. Subarachnoid spaces are first evident around the 32nd day of development near the rhombencephalon.
At this time, the first choroid plexus can be seen, found in the fourth ventricle, although the time at which they first secrete CSF is not yet known. The developing forebrain surrounds the neural cord; as the forebrain develops, the neural cord within it becomes a ventricle forming the lateral ventricles. Along the inner surface of both ventricles, the ventricular wall remains thin, a choroid plexus develops and releasing CSF. CSF fills the neural canal. Arachnoid villi are formed around the 35th week of development, with aracnhoid granulations noted around the 39th, continuing developing until 18 months of age; the subcommissural organ secretes SCO-spondin, which forms Reissner's fiber within CSF assisting movement through the cerebral aqueduct. It disappears during early development. CSF serves several purposes: Buoyancy: The actual mass of the human brain is about 1400–1500 grams; the brain therefore exists in neutral buoyancy, which allows the brain to maintain its density without being impaired by its own weight, which would cut off blood supply and kill neurons in the lower sections without CSF.
Protection: CSF protects the brain tissue from injury when jolted or hit, by providing a fluid buffer that acts as a shock absorber from some forms of mechanical injury. Prevention of brain ischemia: The prevention of brai
Serum albumin referred to as blood albumin, is an albumin found in vertebrate blood. Human serum albumin is encoded by the ALB gene. Other mammalian forms, such as bovine serum albumin, are chemically similar. Serum albumin is produced by the liver, occurs dissolved in blood plasma and is the most abundant blood protein in mammals. Albumin is essential for maintaining the oncotic pressure needed for proper distribution of body fluids between blood vessels and body tissues, it acts as a plasma carrier by non-specifically binding several hydrophobic steroid hormones and as a transport protein for hemin and fatty acids. Too much or too little circulating serum albumin may be harmful. Albumin in the urine denotes the presence of kidney disease. Albumin appears in the urine of normal persons following long standing. Albumin functions as a carrier protein for steroids, fatty acids, thyroid hormones in the blood and plays a major role in stabilizing extracellular fluid volume by contributing to oncotic pressure of plasma.
Because smaller animals function at a lower blood pressure, they need less oncotic pressure to balance this, thus need less albumin to maintain proper fluid distribution. Albumin is synthesized in the liver as preproalbumin which has an N-terminal peptide, removed before the nascent protein is released from the rough endoplasmic reticulum; the product, proalbumin, is in turn cleaved in the Golgi vesicles to produce the secreted albumin. Albumin is a globular, water-soluble, un-glycosylated serum protein of approximate molecular weight of 65,000 Daltons. Albumin is negatively charged; the glomerular basement membrane is negatively charged in the body. According to this theory, that charge plays a major role in the selective exclusion of albumin from the glomerular filtrate. A defect in this property results in nephrotic syndrome leading to albumin loss in the urine. Nephrotic syndrome patients are sometimes given albumin to replace the lost albumin; the general structure of albumin is characterized by several long α helices allowing it to maintain a static shape, essential for regulating blood pressure.
Serum albumin contains eleven distinct binding domains for hydrophobic compounds. One hemin and six long-chain fatty acids can bind to serum albumin at the same time. Serum albumin is distributed in mammals; the human version is human serum albumin. Bovine serum albumin, or BSA, is used in immunodiagnostic procedures, clinical chemistry reagents, cell culture media, protein chemistry research, molecular biology laboratories. Human serum albumin Bovine serum albumin Blood plasma fractionation Chromatography in blood processing Lactalbumin Ovalbumin RCSB Protein Data Bank: Molecule of the Month – Serum Albumin Albumin binding prediction
Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. In vertebrates, it is composed of blood cells suspended in blood plasma. Plasma, which constitutes 55% of blood fluid, is water, contains proteins, mineral ions, carbon dioxide, blood cells themselves. Albumin is the main protein in plasma, it functions to regulate the colloidal osmotic pressure of blood; the blood cells are red blood cells, white blood cells and platelets. The most abundant cells in vertebrate blood are red blood cells; these contain hemoglobin, an iron-containing protein, which facilitates oxygen transport by reversibly binding to this respiratory gas and increasing its solubility in blood. In contrast, carbon dioxide is transported extracellularly as bicarbonate ion transported in plasma. Vertebrate blood is bright red when its hemoglobin is oxygenated and dark red when it is deoxygenated.
Some animals, such as crustaceans and mollusks, use hemocyanin to carry oxygen, instead of hemoglobin. Insects and some mollusks use a fluid called hemolymph instead of blood, the difference being that hemolymph is not contained in a closed circulatory system. In most insects, this "blood" does not contain oxygen-carrying molecules such as hemoglobin because their bodies are small enough for their tracheal system to suffice for supplying oxygen. Jawed vertebrates have an adaptive immune system, based on white blood cells. White blood cells help to resist parasites. Platelets are important in the clotting of blood. Arthropods, using hemolymph, have hemocytes as part of their immune system. Blood is circulated around the body through blood vessels by the pumping action of the heart. In animals with lungs, arterial blood carries oxygen from inhaled air to the tissues of the body, venous blood carries carbon dioxide, a waste product of metabolism produced by cells, from the tissues to the lungs to be exhaled.
Medical terms related to blood begin with hemo- or hemato- from the Greek word αἷμα for "blood". In terms of anatomy and histology, blood is considered a specialized form of connective tissue, given its origin in the bones and the presence of potential molecular fibers in the form of fibrinogen. Blood performs many important functions within the body, including: Supply of oxygen to tissues Supply of nutrients such as glucose, amino acids, fatty acids Removal of waste such as carbon dioxide and lactic acid Immunological functions, including circulation of white blood cells, detection of foreign material by antibodies Coagulation, the response to a broken blood vessel, the conversion of blood from a liquid to a semisolid gel to stop bleeding Messenger functions, including the transport of hormones and the signaling of tissue damage Regulation of core body temperature Hydraulic functions Blood accounts for 7% of the human body weight, with an average density around 1060 kg/m3 close to pure water's density of 1000 kg/m3.
The average adult has a blood volume of 5 litres, composed of plasma and several kinds of cells. These blood cells consist of erythrocytes and thrombocytes. By volume, the red blood cells constitute about 45% of whole blood, the plasma about 54.3%, white cells about 0.7%. Whole blood exhibits non-Newtonian fluid dynamics. If all human hemoglobin were free in the plasma rather than being contained in RBCs, the circulatory fluid would be too viscous for the cardiovascular system to function effectively. One microliter of blood contains: 4.7 to 6.1 million, 4.2 to 5.4 million erythrocytes: Red blood cells contain the blood's hemoglobin and distribute oxygen. Mature red blood cells lack a nucleus and organelles in mammals; the red blood cells are marked by glycoproteins that define the different blood types. The proportion of blood occupied by red blood cells is referred to as the hematocrit, is about 45%; the combined surface area of all red blood cells of the human body would be 2,000 times as great as the body's exterior surface.
4,000–11,000 leukocytes: White blood cells are part of the body's immune system. The cancer of leukocytes is called leukemia. 200,000 -- 500,000 thrombocytes: Also called platelets. Fibrin from the coagulation cascade creates a mesh over the platelet plug. About 55% of blood is blood plasma, a fluid, the blood's liquid medium, which by itself is straw-yellow in color; the blood plasma volume totals of 2.7–3.0 liters in an average human. It is an aqueous solution containing 92% water, 8% blood plasma proteins, trace amounts of other materials. Plasma circulates dissolved nutrients, such as glucose, amino acids, fatty acids, removes waste products, such as carbon dioxide and lactic acid. Other important components include: Serum albumin Blood-clotting factors Immunoglobulins lipoprotein particles Various
Body fluids, bodily fluids, or biofluids are liquids within the human body. In lean healthy adult men, the total body water is about 60% of the total body weight; the exact percentage of fluid relative to body weight is inversely proportional to the percentage of body fat. A lean 70 kg man, for example, has about 42 liters of water in his body; the total body of water is divided between the intracellular fluid compartment and the extracellular fluid compartment in a two-to-one ratio: 28 liters are inside cells and 14 liters are outside cells. The ECF compartment is divided into the interstitial fluid volume - the fluid outside both the cells and the blood vessels - and the intravascular volume - the fluid inside the blood vessels - in a three-to-one ratio: the interstitial fluid volume is about 12 liters, the vascular volume is about 4 liters; the interstitial fluid compartment is divided into the lymphatic fluid compartment - about 2/3's, or 8 liters. The vascular volume is divided into the arterial volume.
Intracellular fluid Extracellular fluid Intravascular fluid Interstitial fluid Lymphatic fluid Transcellular fluid Body fluid is the term most used in medical and health contexts. Modern medical, public health, personal hygiene practices treat body fluids as unclean; this is because they can be vectors for infectious diseases, such as sexually transmitted diseases or blood-borne diseases. Universal precautions and safer sex practices try to avoid exchanges of body fluids. Body fluids can be analyzed in medical laboratory in order to find microbes, cancers, etc. Clinical samples are defined as non-infectious human or animal materials including blood, excreta, body tissue and tissue fluids, FDA-approved pharmaceuticals that are blood products. In medical contexts, it is a specimen taken for diagnostic examination or evaluation, for identification of disease or condition. Methods of sampling of body fluids include: Blood sampling for any blood test, in turn including: Arterial blood sampling, such as radial artery puncture Venous blood sampling called venipuncture Lumbar puncture to sample cerebrospinal fluid Paracentesis to sample peritoneal fluid Thoracocentesis to sample pleural fluid Amniocentesis to sample amniotic fluid A new trend in contemporary art is to use body fluids in art, though there have been rarer uses of blood for quite some time, Marcel Duchamp used semen decades ago.
Examples include: Piss Christ, by Andres Serrano, a photograph of a crucifix submerged in urine. Andy Warhol's Oxidations series, begun in 1977, in which he invited friends to urinate onto a canvas of metallic copper pigments, so that the uric acid would oxidize into abstract patterns. Gilbert and George's The Naked Shit Pictures Hermann Nitsch and Das Orgien Mysterien Theatre use urine, feces and more in their ritual performances. Franko B from 1990 blood letting performances; the cover of the Metallica's album Load is an original artwork entitled "Semen and Blood III", one of three photographic studies by Andres Serrano created in 1990 by mingling the artist's own semen and bovine blood between two sheets of Plexiglas. Blood-borne diseases Clinical pathology Fluid bonding, unprotected sex in long-term relationships Humorism Hygiene Ritual cleanliness Paul Spinrad; the RE/Search Guide to Bodily Fluids. Juno Books. ISBN 1-890451-04-5 John Bourke. Scatalogic Rites of All Nations. Washington, D. C.: W.
H. Lowdermilk. De Luca LA, Menani JV, Johnson AK. Neurobiology of Body Fluid Homeostasis: Transduction and Integration. Boca Raton: CRC Press/Taylor & Francis. ISBN 9781466506930