Lillie's trichrome is a combination of dyes used in histology.
- Lillie's trichrome at StainsFile.info
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Lillie's trichrome is a combination of dyes used in histology.
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Gram stain or Gram staining called Gram's method, is a method of staining used to distinguish and classify bacterial species into two large groups. The name comes from the Danish bacteriologist Hans Christian Gram. Gram staining differentiates bacteria by the chemical and physical properties of their cell walls by detecting peptidoglycan, present in the cell wall of Gram-positive bacteria. Gram-negative cells contain peptidoglycan, but a small layer of it, dissolved when the alcohol is added; this is. Gram-positive bacteria retain the crystal violet dye, thus are stained violet, while the Gram-negative bacteria do not. Both Gram-positive bacteria and Gram-negative bacteria pick up the counterstain; the counterstain, however, is unseen on Gram-positive bacteria because of the darker crystal violet stain. The Gram stain is always the first step in the preliminary identification of a bacterial organism. While Gram staining is a valuable diagnostic tool in both clinical and research settings, not all bacteria can be definitively classified by this technique.
This gives rise to Gram-indeterminate groups. The method is named after its inventor, the Danish scientist Hans Christian Gram, who developed the technique while working with Carl Friedländer in the morgue of the city hospital in Berlin in 1884. Gram devised his technique not for the purpose of distinguishing one type of bacterium from another but to make bacteria more visible in stained sections of lung tissue, he published his method in 1884, included in his short report the observation that the typhus bacillus did not retain the stain. Gram staining is a bacteriological laboratory technique used to differentiate bacterial species into two large groups based on the physical properties of their cell walls. Gram staining is not used to classify archaea archaeabacteria, since these microorganisms yield varying responses that do not follow their phylogenetic groups; the Gram stain is not an infallible tool for diagnosis, identification, or phylogeny, it is of limited use in environmental microbiology.
It is used to make a preliminary morphologic identification or to establish that there are significant numbers of bacteria in a clinical specimen. It cannot identify bacteria to the species level, for most medical conditions, it should not be used as the sole method of bacterial identification. In clinical microbiology laboratories, it is used in combination with other traditional and molecular techniques to identify bacteria; some organisms are Gram-variable. In a modern environmental or molecular microbiology lab, most identification is done using genetic sequences and other molecular techniques, which are far more specific and informative than differential staining. Gram staining has been suggested to be as effective a diagnostic tool as PCR in one primary research report regarding gonococcal urethritis. Gram stains are performed on body biopsy when infection is suspected. Gram stains yield results much more than culturing, is important when infection would make an important difference in the patient's treatment and prognosis.
Gram-positive bacteria have a thick mesh-like cell wall made of peptidoglycan, as a result are stained purple by crystal violet, whereas Gram-negative bacteria have a thinner layer, so do not retain the purple stain and are counter-stained pink by safranin. There are four basic steps of the Gram stain: Applying a primary stain to a heat-fixed smear of a bacterial culture. Heat fixation kills some bacteria but is used to affix the bacteria to the slide so that they don't rinse out during the staining procedure; the addition of iodide, which binds to crystal violet and traps it in the cell Rapid decolorization with ethanol or acetone Counterstaining with safranin. Carbol fuchsin is sometimes substituted for safranin since it more intensely stains anaerobic bacteria, but it is less used as a counterstain. Crystal violet dissociates in aqueous solutions into chloride ions; these ions penetrate through the cell wall and cell membrane of both Gram-positive and Gram-negative cells. The CV+ ion interacts with negatively charged components of bacterial cells and stains the cells purple.
Iodide interacts with CV+ and forms large complexes of crystal violet and iodine within the inner and outer layers of the cell. Iodine is referred to as a mordant, but is a trapping agent that prevents the removal of the CV–I complex and, colors the cell; when a decolorizer such as alcohol or acetone is added, it interacts with the lipids of the cell membrane. A Gram-negative cell loses its outer lipopolysaccharide membrane, the inner peptidoglycan layer is left exposed; the CV–I complexes are washed from the gram-negative cell along with the outer membrane. In contrast, a Gram-positive cell becomes dehydrated from an ethanol treatment; the large CV–I complexes become trapped within the Gram-positive cell due to the multilayered nature of its peptidoglycan. The decolorization step must be timed correctly.
Acid-fast stain, first introduced by Dr. Paul Ehrlich known as the Ziehl–Neelsen staining, is a bacteriological stain used to identify acid-fast organisms Mycobacteria, it is named for two German doctors who modified it: the bacteriologist Franz Ziehl and the pathologist Friedrich Neelsen. Mycobacterium tuberculosis is the most important of this group because it is responsible for tuberculosis. Other important Mycobacterium species involved in human disease are Mycobacterium leprae, Mycobacterium kansasii, Mycobacterium marinum, Mycobacterium bovis, Mycobacterium africanum and members of the Mycobacterium avium complex. Acid-fast organisms like Mycobacterium contain large amounts of lipid substances within their cell walls called mycolic acids; these acids resist staining by ordinary methods such as a Gram stain. It can be used to stain a few other bacteria, such as Nocardia; the reagents used for Ziehl–Neelsen staining are – carbol fuchsin, acid alcohol, methylene blue. Acid-fast bacilli are bright red after staining.
A variation on this staining method is used in mycology to differentially stain acid-fast incrustations in the cuticular hyphae of certain species of fungi in the genus Russula. It is useful in the identification of some protozoa, namely Cryptosporidium and Isospora; the Ziehl–Neelsen stain can hinder diagnosis in the case of paragonimiasis because the eggs in an ovum and parasite sputum sample can be dissolved by the stain, is used in this clinical setting because signs and symptoms of paragonimiasis resemble those of TB. A typical AFB stain procedure involves dropping the cells in suspension onto a slide air drying the liquid and heat fixing the cells; the slide is flooded with carbol fuchsin, heated to dry and rinsed off in tap water. The slide is flooded with a 1% solution of hydrochloric acid in isopropyl alcohol to remove the carbol fuchsin, thus removing the stain from cells that are unprotected by a waxy lipid layer. Thereafter, the cells are stained in methylene blue and viewed under a microscope under oil immersion.
Studies have shown. An AFB culture should be performed along with an AFB stain. Carbol fuchsin stains every cell; when they are de-stained with acid-alcohol, only non-acid-fast bacteria get de-stained since they do not have a thick, waxy lipid layer like acid-fast bacteria. When counter stain is applied, non-acid-fast bacteria pick it up and become blue or green when viewed under the microscope. Acid-fast bacteria retain carbol fuchsin. 1% sulfuric acid alcohol for actinomycetes, nocardia. 0.5–1% sulfuric acid alcohol for oocysts of isospora, cyclospora. 0.25–0.5% sulfuric acid alcohol for bacterial endospores. Brucella differential stain – glacial acetic acid used, no heat applied, secondary stain is Loeffler's methylene blue. Kinyoun modification is available. A protocol in which a detergent is substituted for the toxic phenol in the fuchsin staining solution. Lowenstein–Jensen medium Gram stain "Microbiology with Diseases by Body System", Robert W. Bauman, 2009, Pearson Education, Inc. Morello, Josephine A. Paul A. Granato, Marion E. Wilson, Verna Morton.
Laboratory Manual and Workbook in Microbiology: Applications to Patient Car. 10th ed. Boston: McGraw-Hill Higher Education, 2006. Print. Ziehl–Neelsen protocol. Media related to Ziehl-Neelsen stain at Wikimedia Commons
A carbohydrate is a biomolecule consisting of carbon and oxygen atoms with a hydrogen–oxygen atom ratio of 2:1 and thus with the empirical formula Cmn. This formula holds true for monosaccharides; some exceptions exist. The carbohydrates are technically hydrates of carbon; the term is most common in biochemistry, where it is a synonym of saccharide, a group that includes sugars and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides and polysaccharides. Monosaccharides and disaccharides, the smallest carbohydrates, are referred to as sugars; the word saccharide comes from the Greek word σάκχαρον, meaning "sugar". While the scientific nomenclature of carbohydrates is complex, the names of the monosaccharides and disaccharides often end in the suffix -ose, as in the monosaccharides fructose and glucose and the disaccharides sucrose and lactose. Carbohydrates perform numerous roles in living organisms. Polysaccharides serve as structural components; the 5-carbon monosaccharide ribose is an important component of coenzymes and the backbone of the genetic molecule known as RNA.
The related deoxyribose is a component of DNA. Saccharides and their derivatives include many other important biomolecules that play key roles in the immune system, preventing pathogenesis, blood clotting, development, they are found in a wide variety of processed foods. Starch is a polysaccharide, it is abundant in cereals and processed food based on cereal flour, such as bread, pizza or pasta. Sugars appear in human diet as table sugar, lactose and fructose, both of which occur in honey, many fruits, some vegetables. Table sugar, milk, or honey are added to drinks and many prepared foods such as jam and cakes. Cellulose, a polysaccharide found in the cell walls of all plants, is one of the main components of insoluble dietary fiber. Although it is not digestible, insoluble dietary fiber helps to maintain a healthy digestive system by easing defecation. Other polysaccharides contained in dietary fiber include resistant starch and inulin, which feed some bacteria in the microbiota of the large intestine, are metabolized by these bacteria to yield short-chain fatty acids.
In scientific literature, the term "carbohydrate" has many synonyms, like "sugar", "saccharide", "ose", "glucide", "hydrate of carbon" or "polyhydroxy compounds with aldehyde or ketone". Some of these terms, specially "carbohydrate" and "sugar", are used with other meanings. In food science and in many informal contexts, the term "carbohydrate" means any food, rich in the complex carbohydrate starch or simple carbohydrates, such as sugar. In lists of nutritional information, such as the USDA National Nutrient Database, the term "carbohydrate" is used for everything other than water, fat and ethanol; this includes chemical compounds such as acetic or lactic acid, which are not considered carbohydrates. It includes dietary fiber, a carbohydrate but which does not contribute much in the way of food energy though it is included in the calculation of total food energy just as though it were a sugar. In the strict sense, "sugar" is applied for sweet, soluble carbohydrates, many of which are used in food.
The name "carbohydrate" was used in chemistry for any compound with the formula Cm n. Following this definition, some chemists considered formaldehyde to be the simplest carbohydrate, while others claimed that title for glycolaldehyde. Today, the term is understood in the biochemistry sense, which excludes compounds with only one or two carbons and includes many biological carbohydrates which deviate from this formula. For example, while the above representative formulas would seem to capture the known carbohydrates and abundant carbohydrates deviate from this. For example, carbohydrates display chemical groups such as: N-acetyl, carboxylic acid and deoxy modifications. Natural saccharides are built of simple carbohydrates called monosaccharides with general formula n where n is three or more. A typical monosaccharide has the structure H–x–y–H, that is, an aldehyde or ketone with many hydroxyl groups added one on each carbon atom, not part of the aldehyde or ketone functional group. Examples of monosaccharides are glucose and glyceraldehydes.
However, some biological substances called "monosaccharides" do not conform to this formula and there are many chemicals that do conform to this formula but are not considered to be monosaccharides. The open-chain form of a monosaccharide coexists with a closed ring form where the aldehyde/ketone carbonyl group carbon and hydroxyl group react forming a hemiacetal with a new C–O–C bridge. Monosaccharides can be linked togeth
Wright's stain is a histologic stain that facilitates the differentiation of blood cell types. It is classically a mixture of methylene blue dyes, it is used to stain peripheral blood smears, urine samples, bone marrow aspirates which are examined under a light microscope. In cytogenetics, it is used to stain chromosomes to facilitate diagnosis of diseases, it is named for James Homer Wright, who devised the stain, a modification of the Romanowsky stain, in 1902. Because it distinguishes between blood cells, it became used for performing differential white blood cell counts, which are ordered when conditions such as infection or leukemia are suspected; the related stains are known as the buffered Wright stain, the Wright-Giemsa stain, the buffered Wright-Giemsa stain, specific instructions depend on the solutions being used, which may include eosin Y, azure B, methylene blue. The May–Grünwald stain, which produces a more intense coloration takes a longer time to perform. Urine samples stained with Wright's stain will identify eosinophils, which can indicate interstitial nephritis or urinary tract infection.
White blood cells stained with Wright's stain: Diff-Quick Leishman stain List of histologic stains that aid in diagnosis of cutaneous conditions Romanowsky stain Staining
In biology and biochemistry, a lipid is a biomolecule, soluble in nonpolar solvents. Non-polar solvents are hydrocarbons used to dissolve other occurring hydrocarbon lipid molecules that do not dissolve in water, including fatty acids, sterols, fat-soluble vitamins, diglycerides and phospholipids; the functions of lipids include storing energy and acting as structural components of cell membranes. Lipids have applications in the food industries as well as in nanotechnology. Scientists sometimes broadly define lipids as amphiphilic small molecules. Biological lipids originate or in part from two distinct types of biochemical subunits or "building-blocks": ketoacyl and isoprene groups. Using this approach, lipids may be divided into eight categories: fatty acids, glycerophospholipids, sphingolipids and polyketides. Although the term "lipid" is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides. Lipids encompass molecules such as fatty acids and their derivatives, as well as other sterol-containing metabolites such as cholesterol.
Although humans and other mammals use various biosynthetic pathways both to break down and to synthesize lipids, some essential lipids can't be made this way and must be obtained from the diet. In 1815, Henry Braconnot classified lipids in two categories and huiles. In 1823, Michel Eugène Chevreul developed a more detailed classification, including oils, tallow, resins and volatile oils. In 1827, William Prout recognized fat, along with protein and carbohydrate, as an important nutrient for humans and animals. For a century, chemists regarded "fats" as only simple lipids made of fatty acids and glycerol, but new forms were described later. Theodore Gobley discovered phospholipids in mammalian brain and hen egg, called by him as "lecithins". Thudichum discovered in human brain some phospholipids and sphingolipids; the terms lipoid, lipin and lipid have been used with varied meanings from author to author. In 1912, Rosenbloom and Gies proposed the substitution of "lipoid" by "lipin". In 1920, Bloor introduced a new classification for "lipoids": simple lipoids, compound lipoids, the derived lipoids.
The word "lipid", which stems etymologically from the Greek lipos, was introduced in 1923 by Gabriel Bertrand. Bertrands included in the concept not only the traditional fats, but the "lipoids", with a complex constitution. In 1947, T. P. Hilditch divided lipids into "simple lipids", with greases and waxes, "complex lipids", with phospholipids and glycolipids. Fatty acids, or fatty acid residues when they are part of a lipid, are a diverse group of molecules synthesized by chain-elongation of an acetyl-CoA primer with malonyl-CoA or methylmalonyl-CoA groups in a process called fatty acid synthesis, they are made of a hydrocarbon chain. The fatty acid structure is one of the most fundamental categories of biological lipids, is used as a building-block of more structurally complex lipids; the carbon chain between four and 24 carbons long, may be saturated or unsaturated, may be attached to functional groups containing oxygen, halogens and sulfur. If a fatty acid contains a double bond, there is the possibility of either a cis or trans geometric isomerism, which affects the molecule's configuration.
Cis-double bonds cause the fatty acid chain to bend, an effect, compounded with more double bonds in the chain. Three double bonds in 18-carbon linolenic acid, the most abundant fatty-acyl chains of plant thylakoid membranes, render these membranes fluid despite environmental low-temperatures, makes linolenic acid give dominating sharp peaks in high resolution 13-C NMR spectra of chloroplasts; this in turn plays an important role in the function of cell membranes. Most occurring fatty acids are of the cis configuration, although the trans form does exist in some natural and hydrogenated fats and oils. Examples of biologically important fatty acids include the eicosanoids, derived from arachidonic acid and eicosapentaenoic acid, that include prostaglandins and thromboxanes. Docosahexaenoic acid is important in biological systems with respect to sight. Other major lipid classes in the fatty acid category are the fatty esters and fatty amides. Fatty esters include important biochemical intermediates such as wax esters, fatty acid thioester coenzyme A derivatives, fatty acid thioester ACP derivatives and fatty acid carnitines.
The fatty amides include N-acyl ethanolamines, such as the cannabinoid neurotransmitter anandamide. Glycerolipids are composed of mono-, di-, tri-substituted glycerols, the best-known being the fatty acid triesters of glycerol, called triglycerides; the word "triacylgl
Giemsa stain, named after German chemist and bacteriologist Gustav Giemsa, is used in cytogenetics and for the histopathological diagnosis of malaria and other parasites. It is specific for the phosphate groups of DNA and attaches itself to regions of DNA where there are high amounts of adenine-thymine bonding. Giemsa stain is used in Giemsa banding called G-banding, to stain chromosomes and used to create a karyogram, it can identify chromosomal aberrations such as rearrangements. It stains the trophozoite Trichomonas vaginalis, which presents with greenish discharge and motile cells on wet prep. Giemsa stain is a differential stain, such as when it is combined with Wright stain to form Wright-Giemsa stain, it can be used to study the adherence of pathogenic bacteria to human cells. It differentially stains bacterial cells purple and pink respectively, it can be used for histopathological diagnosis of malaria and some other spirochete and protozoan blood parasites. It is used in Wolbachia cell stain in Drosophila melanogaster.
Giemsa stain is a classic blood film stain for peripheral blood smears and bone marrow specimens. Erythrocytes stain pink, platelets show a light pale pink, lymphocyte cytoplasm stains sky blue, monocyte cytoplasm stains pale blue, leukocyte nuclear chromatin stains magenta, it is used to visualize the classic "safety pin" shape in Yersinia pestis. Giemsa stain is used to visualize chromosomes. Giemsa stains the fungus Histoplasma, Chlamydia bacteria, can be used to identify mast cells. Giemsa's solution is a mixture of methylene blue and Azure B; the stain is prepared from commercially available Giemsa powder. A thin film of the specimen on a microscope slide is fixed in pure methanol for 30 seconds, by immersing it or by putting a few drops of methanol on the slide; the slide is immersed in a freshly prepared 5% Giemsa stain solution for 20–30 minutes flushed with tap water and left to dry. Biological stains and staining protocols Histology Leishman stain Microscopy Romanowsky stain Wright's stain
Gömöri trichrome stain is a histological stain used on muscle tissue. It can be used to test for certain forms of mitochondrial myopathy, it is named for George Gömöri, who developed it in 1950. Media related to Gömöri trichrome stain at Wikimedia Commons