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231 results found

14-3-3 protein

14-3-3 proteins are found in the cerebrospinal fluid (CSF), and are currently used to help identify patients with sporadic Creutzfeldt-Jakob disease (sCJD). Seven distinct 14-3-3 proteins have been found in humans. In diagnosing sCJD, the sensitivity of 14-3-3 protein is 92% and its specifici...

1p19q codeletion

1p19q codeletion stands for the combined loss of the short arm chromosome 1 (i.e. 1p) and the long arm of chromosome 19 (i.e. 19q) and is recognized as a genetic marker predictive of therapeutic response to both chemotherapy and combined chemoradiotherapy and overall longer survival in patients ...

2005 WHO histological classification of odontogenic tumors

The 2005 WHO histological classification of odontogenic tumors lays out a classification system for neoplasms and other tumors related to the odontogenic apparatus. At the time of writing (2016), it is still the most widely used classification system although a new revision is due to come up in ...

2-hydroxyglutarate

2-hydroxyglutarate is a metabolite that accumulates in the brains of patients with IDH-1 mutated (IDH-1 positive) brain tumors, particularly diffuse low-grade gliomas. Although not in widespread clinical use, it is likely that 2-hydroxyglutarate, which resonates at 2.25 ppm, will be able to be d...

Adenoma-carcinoma sequence

The adenoma-carcinoma sequence refers to a stepwise pattern of mutational activation of oncogenes (e.g. K-ras) and inactivation of tumor suppressor genes (e.g. p53) that results in cancer. An oncogene is a gene that has the potential to cause cancer. In tumor cells, these are often mutated or ex...

Alpha fetoprotein

Alpha fetoprotein (AFP) is an important plasma protein synthesized by the yolk sac and fetal liver. In adults its main utility is as a tumor marker, primarily for hepatocellular carcinoma or teratoma. Functionally it is the fetal homologue of albumin i.e. it acts as a major carrier protein in th...

Alpha thalassemia/intellectual disability syndrome X-linked (ATRX) gene (tumor marker)

Alpha-thalassemia/intellectual disability syndrome X-linked (ATRX) gene is an important genomic marker of gliomas and is either intact (ATRX wild-type) or mutated (ATRX-mutant) and is correlated with other important genomic markers including IDH, 1p19q codeletion and p53 expression 1,2. ATRX a...

Alzheimer type I glia

Alzheimer type I glia are a type of glial cell. They are large multinucleated astrocytes encountered in glial tumors and progressive multifocal leukoencephalopathy (PML) 1.

Alzheimer type II glia

Alzheimer type II glia are a type of glial cell. They are a pathological reactive astrocyte seen in the brain, unrelated to Alzheimer disease. They are seen most frequently in Wilson disease, but also in other systemic metabolic disorders, particularly those with elevated ammonia levels, typical...

Amino acids

Amino acids are the monomeric building blocks of proteins. Amino acids concatenate into chains, which are arbitrarily divided into peptides, polypeptides, or proteins according to chain length. Generally, chains of 10 or fewer amino acids are deemed to be peptides, chain length from 10-100 are p...

Amylase

Amylase is widely employed as a marker of acute pancreatitis and a significant elevation is diagnostic. Physiology α-amylase is a digestive enzyme that is predominantly secreted by the acinar cells of the exocrine pancreas. It is also secreted by the salivary glands. Pancreatic amylase is enco...

Anemia

Anemia is the presence of reduced hemoglobin in the blood. Formally, the World Health Organization (WHO) defines anemia by the hemoglobin concentration in the blood according to age and sex 1: adult men: <130 g/L adult women: <120 g/L Values for pregnant women and children are different. Pat...

Anaplastic lymphoma kinase (ALK) gene rearrangements

Anaplastic lymphoma kinase (ALK) gene rearrangements are known to occur in association with several tumors. The genes codes for an enzyme called anaplastic lymphoma kinase (ALK) or ALK tyrosine kinase receptor / CD246 which is thought o play a role in the brain development and exerts its effects...

Angiotensin converting enzyme

Angiotensin converting enzyme (ACE) a central component of the renin-angiotensin system (RAS) which assists in blood pressure control by regulating the volume of fluids in the body. Normal individuals can have small volume circulating in serum/blood. Measurement Normally measured as nanomoles...

Apoptosis

Apoptosis (plural: apoptoses), also known as programmed cell death (PCD) is a term to describe the process of regulated cell death. This is in contrast to necrosis, which is unregulated cell death often secondary to external factors 1. Apoptosis occurs in cells which are destined to die by acti...

Aspergillus clavatus

Aspergillus clavatus is one of the species of Aspergillus that can cause pathology in humans. It is allergenic and causes a hypersensitivity pneumonitis called malt-workers lung. See also Aspergillus Aspergillus fumigatus Aspergillus flavus Aspergillus clavatus

Aspiration

Aspiration occurs if liquid or solid material enters the subglottic lower respiratory tract. Terminology The term aspiration is used if material passes below the level of the vocal folds, i.e. subglottic. If material enters the larynx but remains above the vocal folds this is called penetratio...

Astrocytes

Astrocytes are cells of the central nervous system which act as both physical and physiological support for the neurons that are embedded between them. They are particularly abundant in the grey matter, where they are the most abundant glial cells 1. They are highly branched and contribute to t...

Atresia

Atresia (plural: atresias) refers to a situation where there is absence, underdevelopment or abnormal closure, of a normal anatomical tubular structure or opening. Contrast this with agenesis which refers to the complete absence of any anatomical structure including its primordial precursors. ...

Atrophy

Atrophy is a reduction in the size of an organ/tissue. Microscopically this is a reduction in cell size/volume caused by a reduction in protein synthesis and/or increased protein degradation 1. Atrophy may be physiologic or pathological. Physiological atrophy is commonly seen in the normal dev...

Atypical pulmonary carcinoid tumor

An atypical pulmonary carcinoid tumor is a more aggressive variant of a peripheral pulmonary carcinoid tumor. They are considered intermediate grade neoplasms and have the same “carcinoid morphology,” but with mitotic rates increased (at 2–10 mitoses per 2 mm2) where the tumor might also be pun...

Atypical small acinar proliferation

Atypical small acinar proliferations (ASAP) are premalignant lesions of the prostate, which can be found in as many as 5% of prostate biopsies. They are suspicious glands without adequate histologic atypia to establish a definitive diagnosis of prostate cancer. Some studies showed that there is ...

Basic organic elements

The basic organic elements are those chemical elements that are fundamental to life and are constituents of every or almost every organic molecule, and therefore all life known on earth. carbon hydrogen oxygen nitrogen

Basic reproductive number

The basic reproductive number (R0), also known as just the reproductive number, basic reproduction number, basic reproductive ratio, reproduction number, R nought or R zero, is the average number of cases in a susceptible population that will be generated by an existing diseased individual carry...

Beryllium

Beryllium (chemical symbol Be) is an alkaline earth metallic element, that has no known function in any organism. Unfortunately beryllium is very poisonous, manifesting as chronic beryllium lung disease, which causes premature mortality in one third 1. Chemistry Basic chemistry Beryllium is a...

Biotin

Biotin (less commonly known as vitamin B7) is a water-soluble vitamin, part of the vitamin B complex, and a coenzyme for many reactions, including gluconeogenesis and the synthesis of fatty acids and amino acids. Biotin deficiency is very rare. Biotin excess does not seem to produce any ill-ef...

Blood

Blood comprises a fluid component called plasma, in which lie several cell lineages, namely the white blood cells, red blood cells and platelets. In an average adult male the total volume of blood is ~5.5 L.

BRAF

BRAF (B-Raf proto-oncogene serine/threonine-protein kinase) is a proto-oncogene, encoding for a serine/threonine protein kinase. Mutations of BRAF are the most common alteration of the RAS/MAPK pathway and these have been identified in a variety of tumors and congenital syndromes including 1-5: ...

Brunner glands

Brunner glands are compound tubular submucosal glands found in the duodenum. They are only found proximal to the sphincter of Oddi. Related pathology Brunner gland hyperplasia Brunner gland adenoma

CA-125

CA-125 is a high-molecular-weight glycoprotein found on the surface of Mullerian and coelomic epithelial-derived cell types, and is the best known tumor marker for epithelial ovarian cancer 6. Importantly, it may also be elevated in several other conditions (see differential diagnosis section be...

CA 15-3

Carcinoma antigen 15-3, usually shortened to CA 15-3 is a tumor marker used in monitoring breast cancer. The test detects levels of MUC-1, a mucin protein in the blood. MUC-1 is thought to be important in the invasiveness and metastasization of cancer cells. Physiology MUC-1 is a normal epithe...

CA 19-9

CA 19-9 (carbohydrate antigen 19-9 or cancer antigen 19-9) is a serum antigen (monosialoganglioside) that has increased diagnostic use in the management of several malignancies, mainly of hepatopancreaticobiliary origin. It is non-specific, however, and can rise in both malignant and non-maligna...

CA 27-29

CA 27-29 is a tumor marker and is a soluble form of glycoprotein MUC1. It may be elevated in patients with breast cancer. Tumors of the colon, stomach, kidney, lung, ovary, pancreas, uterus, and liver may also raise CA 27-29 levels. Certain non-malignant conditions are also associated with its ...

CEA

Serum CEA (carcinoembryonic antigen) is a cell-adhesive glycoprotein that was discovered in colorectal cancer in 1965, and is hence one of the oldest and most used tumor markers. Its name derives from its normal expression in fetoembryonic liver, gut and pancreas tissue. Normal range of CEA is ...

Cerumen

Cerumen, also known as earwax, is a natural secretion produced by, and found within the external auditory canal (EAC). It has important roles as part of the first-line of defense of the ear from micro-organisms and optimizing function of the tympanic membrane and EAC. Secretion Cerumen is secr...

Charcot-Leyden crystals

Charcot-Leyden crystals consist of collections of bipyramidal crystalloid made up of eosinophilic membrane proteins, which occur in: asthma other eosinophilic lung disease 2 certain cases of sinusitis (e.g. allergic fungal sinusitis) They may be detected in the sputum or sinus secretions wi...

Chemical element

There are now 118 confirmed chemical elements in the periodic table. A chemical element describes atoms which share the same specific number of protons in their nucleus (atomic number). For example, all atoms of carbon, regardless of their number of electrons (determines ionization) or neutrons ...

Chemical element notation

The notation of the 118 known chemical elements is prescribed by the International Union of Pure and Applied Chemistry (IUPAC) 1. Each chemical element has a long name and a symbol. In English the long name is only capitalized as part of title or sentence case. Chemical element names are not p...

Choristoma

A choristoma is simply a collection of microscopically normal cells or tissues in an abnormal location. This is different to a hamartoma which is derived only from local tissues. Examples include: adrenal choristoma (myelolipoma) nasopharyngeal choristoma facial nerve choristoma optic nerve...

Choroidal epithelial cells

Choroidal epithelial cells are one of the three types of ependymal cells, themselves a type of glial cell. They cover the surface of the choroid plexus and produce cerebrospinal fluid (CSF). 1.

Chromium

Chromium (chemical symbol Cr) has been categorized previously as one of the trace elements, and has been said to be important for glucose homeostasis, but this is now contentious (see below). Chemistry Basic chemistry Chromium has the atomic number 24 with an atomic weight of 51.9961 g/mol. L...

Chromogranin A

Chromogranin A (CgA) is an acidic secretory glycoprotein found in the secretory granules of neuroendocrine cells and neurons, as is a member of the granin family of proteins. It can be used both for immunohistochemical stains and as a serum marker 4. Immunohistochemistry Chromogranin A is use...

Circumferential resection margin

The circumferential resection margin (CRM) is a term used in rectal carcinoma excision surgery (such as total mesorectal excision (TME)). Pathologic evaluation of the resection margin on the excised rectum has been considered important for determining the risk of local recurrence. A margin of ≤...

Cobalt

Cobalt (chemical symbol Co) is an essential trace element. Its most important function in humans is as the active metal atomic center of vitamin B12. Chemistry Basic chemistry Cobalt is a shiny grey-silvery transition metal with an atomic number 27 and atomic weight 58.93. Its oxidation state...

Columnar alteration with prominent apical snouts and secretions

Columnar alteration with prominent apical snouts and secretions (CAPSS) is a pathological entity encountered when breast biopsies are done for investigation of punctate or amorphous calcifications. CAPSS involves the terminal ductal and lobular units (TDLU's). It is sometimes classified under t...

Congestion

Congestion is a pathological term referring to reduced blood flow out from tissues, which may be localized or systemic 1. Clinical presentation Congestion commonly presents with increased swelling and edema of tissues where blood flow is reduced. With prolonged congestion, the tissues may beco...

Copper

Copper (chemical symbol Cu) is one of the trace elements. It has an important biological role as a redox agent and as a cofactor in cuproproteins, facilitating many vital metabolic reactions. Chemistry Basic chemistry Copper is a transition metal with the atomic number 29 and an atomic weight...

Cowdry bodies

Cowdry bodies are neuronal intranuclear inclusions seen in Herpes simplex virus infections 1. Pathology Cowdry bodies are in fact fixation artifacts and not directly the result of the intracellular virus 2.

C-reactive protein

C-reactive protein (CRP) is an acute phase reactant commonly measured in clinical practice as a marker of inflammation and to monitor disease severity, disease course and treatment response. It should not be confused with protein C (an anticoagulant) or C-peptide (a component of proinsulin). Ph...

Creatine kinase

Creatine kinase (CK), also known as creatine phosphokinase (CPK), is a key enzyme, for energy production in mitochondria and muscle tissues. It is important as a diagnostic assay in clinical practice, primarily because inflamed/injured muscle releases creatine kinase into the circulation 1. Phy...

Cyst

A cyst is an abnormal fluid-filled structure which is lined by epithelium; with one exception: lung cysts may contain gas or fluid. By contradistinction, a pseudocyst lacks an epithelial lining and instead has a vascular and fibrotic capsule. Cysts are extremely common and found in most organs....

Decomposition

Decomposition of the human body occurs soon after death and is of relevance to radiology in the fields of post mortem and forensic radiology. Pathology Decomposition occurs due to two main processes 1,2: autolysis: degradation by destructive enzymes released by dying cells in the body putref...

Desmoplasia

Desmoplasia (also known as a desmoplastic reaction) is the term used by pathologists to refer to the growth of fibrous tissue around disease, usually cancer. However in dermatopathology, desmoplasia may also be seen with benign, as well as malignant, conditions. Terminology Pathologists prefer...

Diverticulum

Diverticula are outpouchings of a hollow viscus and can be either true or false. Occasionally a diverticulum is used in a more general sense to mean the outpouching of other anatomical structures, e.g. frontal intersinus septal cells are hypothesized to form as diverticula from the frontal sinu...

EGFR mutation

Epidermal growth factor receptor (EGFR) mutation can be expressed in a large proportion of non-small cell lung carcinomas (NSCLC). However, certain subtypes such as invasive mucinous adenocarcinoma of the lung can have very low expression. The presence of this mutation can be assessed on biopsy...

Elevated vitamin B12

Elevated vitamin B12 (also known as hypervitaminosis B12 or hypercobalaminemia) is most important as a diagnostic and prognostic marker for malignant disease 1,3. Very high serum levels of vitamin B12, following dietary megadosing, does not seem to have any observable deleterious effects 2.

Embolism

Embolism describes intravascular material that is carried from its origin location downsteam to a distant area. The most common type of embolism is that which is derived from a thrombus, such as in the case of pulmonary embolism or stroke. Types of embolism thromboembolism air embolism amnio...

Endemic

The epidemiological term endemic is used for any condition that persists within a particular community/locale without the need for external input of new disease, i.e. the disease in question has attained a steady-state in the affected population 1. For this to happen the basic reproductive numbe...

Eosinophil

Eosinophils, also less commonly known as acidophils, are myeloid granulocytes and form one of the main types of white blood cells. Their counts are routinely measured as part of a full blood count. They have important roles in fighting parasitic infections, but are increasingly recognized as hav...

Eosinophilia

Eosinophilia is defined as an abnormally high level of eosinophils in the blood, this is usually defined as >500 cells/μL (normal eosinophil level: <450 cells/μL). Hypereosinophilia is defined as >1500 cells/μL and is usually due to hematological malignancy 1,2. This article includes recommenda...

Ependymal cells

Ependymal cells are one of the four main types of glial cells, and themselves encompass three types of cells 1: ependymocytes: line the ventricles of the brain and central canal of the spinal cord tanycytes: line the floor of the third ventricle overlying the median eminence of the hypothalam...

Ependymal rosettes (ependymoma)

Ependymal rosettes correspond to a histologic architectural pattern that very characteristic of ependymomas, as tumor cells form structures similar to the lining of normal ventricles. They are characterized by a halo or spoke-wheel arrangement of tumor cells surrounding an empty central tubule l...

Ependymocytes

Ependymocytes are one of the three types of ependymal cells, which in turn are one of the four principles types of glial cells, and are found lining the ventricular system of the brain and the central canal of the spinal cord 1. They do not form a water-tight barrier between the cerebrospinal ...

Epidemic

An epidemic is defined for a condition that is normally rare in a population but in a short space of time has become widespread 1. It may refer to both infectious diseases (for example, Zika virus epidemic in Brazil 6) but also other conditions, e.g. the obesity epidemic. For example, when COVI...

Epithelial membrane antigen (EMA)

Epithelial membrane antigen (EMA) is a commonly used target for immunohistochemisty, found on the surface of many epithelial cells and thus present in a wide variety of tumors. It also is sometimes seen within the cytoplasm of cells (e.g. perinuclear dot in ependymomas).

Erythrocyte sedimentation rate

Erythrocyte sedimentation rate (ESR) is a non-specific marker of acute inflammation which is seen in a very wide spectrum of pathologies. In recent years it has been sidelined by the use of C-reactive protein and other acute phase markers but it still has an important role to play in the managem...

Essential elements

The essential elements are chemical elements which are essential for optimal physical and mental well being, and required in bulk (cf. trace elements) quantities in a normal human diet. The elements are: calcium magnesium phosphorus potassium sodium

Estimated glomerular filtration rate

The estimated glomerular filtration rate (eGFR) is widely used as a surrogate marker of renal function and is mathematically-derived from the patient's serum creatinine, using their age, sex and ethnicity. Calculation The eGFR is calculated using a four variables Modification of Diet in Renal...

Exophytic

Exophytic is a descriptive term used by radiologists/pathologists to describe solid organ lesions arising from the outer surface of the organ of origin. Literally exophytic only refers to those lesions arising from the outer surface, however radiologists and pathologists use the term to include...

Extranodal extension

Extranodal extension refers to the growth of a nodal cancer metastasis beyond the confines of the capsule of a lymph node into adjacent tissues. Less preferred synonyms include extranodal spread, extracapsular extension, or extracapsular spread. This finding holds prognostic implications. For e...

Fecal calprotectin

Fecal calprotectin (FCAL) is a protein which is a marker of inflammation of the gut used as a diagnostic tool and marker of disease activity for Crohn disease and ulcerative colitis. Biochemistry Calprotectin is a protein complex from the S-100 family, which is formed of three polypeptide chai...

Fistula

A fistula (plural: fistulae) is an abnormal connection between two epithelial surfaces such as between hollow organs, skin or vessels. Conventionally, the name of a specific fistula type is a combination of the two organs For discussions of specific fistulae please refer to individual articles....

Flexner-Wintersteiner rosette

The presence of Flexner-Wintersteiner rosette is characteristic for retinoblastoma but is also seen in pineoblastoma and medulloepitheliomas.

Fracture healing

Fracture healing occurs naturally after traumatic bony disruption. This process begins with hemorrhage and progresses through three stages: inflammatory reparative remodelling This process can be supported by various treatment options with immobilization a mainstay; inappropriate treatment m...

Gadolinium

Gadolinium (chemical symbol Gd) is a metallic element that can be chelated into paramagnetic complexes for use as gadolinium contrast media. Chemistry Basic chemistry Gadolinium is a silvery rare earth metal, and a member of the lanthanides, with the atomic number 64 and an atomic weight of 1...

Gene and protein notation

Correct usage of gene and protein notation has been laid down by the HUGO Gene Nomenclature Committee (HGNC) and on Radiopaedia we have decided to reflect this official guidance. In concordance with this standard scientific practice, gene symbols are italicized on Radiopaedia, but when the full...

Gene expression classifier

A gene expression classifier (GEC) test is a developing technology in the analysis of indeterminate thyroid nodules, using cells from a fine needle aspiration. The most common commercially available GEC in the United States is known as AFIRMA. The test is designed to use molecular markers to he...

Glial cells

Glial cells, or neuroglia, are cells that surround the neurons of the central nervous system embedded between them, providing both structural and physiological support 1-3. Together they account for almost half of the total mass 1 and 90% of all cells of the central nervous system 3. These numb...

Glial fibrillary acid protein (GFAP)

Glial fibrillary acid protein (GFAP) is a commonly used target for immunohistochemistry and is positive in many glial cells and tumors of glial origin. GFAP is the building block for intermediate filaments which are abundant in the cytoplasms particularly of astrocytes. Related pathology Alex...

Gliosis

Gliosis is the focal proliferation of glial cells in the CNS in response to insult. By strict definition, gliosis is not synonymous with encephalomalacia which is the end result of liquefactive necrosis of brain parenchyma following an insult. Radiologically they share similar features and the d...

Glucagon

Glucagon is a polypeptide hormone central to the regulation of glucose homeostasis, acting as an antagonist to insulin. In imaging it is used as an antiperistaltic agent in GI studies, although its clinical efficacy is controversial. Structure Glucagon is a 29-amino acid polypeptide hormone t...

Hematoma

Hematomas are the name given to localized collections of blood and they can form virtually anywhere in the body. They often form secondary to trauma or surgery but spontaneous formation is also not uncommon, especially in those with coagulation disorders or on anticoagulant therapy. Hematomas m...

Hemoglobin

Hemoglobin is the oxygen-carrying molecule in red blood cells. Structure Hemoglobin is a tetrameric protein molecule composed of four subunits. Each subunit consists of an iron-containing cyclic heme component linked to a polypeptide chain, the polypeptides are together known as globin. Each h...

Haggitt level

The Haggitt level is a histopathological term used for describing the degree of infiltration from a malignant polypoidal lesion. Levels of invasion 0: carcinoma in situ or intramucosal carcinoma 1: invasion of the submucosa, but limited to the head of the polyp 2: invasion extending into the...

Hamartoma

A hamartoma is a benign tumor-like malformation that consists of a collection of architecturally disorganized cells located in an area of the body where the cells are normally found. It is often due to abnormal development. In radiology, hamartomas often mimic malignancy. Several hamartomata ha...

Heavy metals

Heavy metals is a vague term for a group of metallic chemical elements that under some definitions can refer to the vast majority of the metals known to science. In biological/medical terms heavy metals are a much smaller group, that for many practitioners is restricted to those that are potenti...

Hepascore

Hepascore is a biochemical severity scoring system based on liver function tests in predicting the extent of liver fibrosis/cirrhosis in patients with hepatitis C infection. Hepascore may also be applicable to other liver diseases and is being trialed for fatty liver disease and hepatitis B infe...

Hepatoblastoma histological classification

Although hepatoblastomas can be histologically classified into a variety of subtypes, it is important to remember that with the possible exception of small cell undifferentiated subtype, prognosis is independent of histology when adjusted for stage gender and age 1. major categories epithelial...

HER-2 mutations in lung cancer

Human epidermal growth factor receptor 2 (HER-2) mutations may be detected in approximately 3% of lung adenocarcinomas 1. Radiographic features CT Early studies have suggested HER2-mutant tumors exhibit more aggressive features in general and tend to: exhibit a locally-invasive behavior comp...

Hernia (general)

Hernias (or herniae) are a common pathological entity, in which an anatomical structure passes into an abnormal location via an opening. The opening may be a normal physiological aperture (e.g. hiatus hernia: stomach passes through the diaphragmatic esophageal hiatus) or pathological. Iatrogeni...

Histological stains

Histological stains are chemicals dyes used to treat histological specimens to make tissues more readily visible by light microscopy and demonstrate underlying characteristics of the tissue. There are many stains, some with very specific uses, whereas other (e.g. hematoxylin and eosin stain (H&E...

Histology of blood vessels

Blood vessels, namely arteries and veins, are composed of endothelial cells, smooth muscle cells and extracellular matrix (including collagen and elastin). These are arranged into three concentric layers (or tunicae): intima, media and adventitia. the intima (or tunica intima) inner layer abut...

Homer Wright rosettes

Homer Wright rosettes are differentiated tumor cells grouped around a central region containing neuropil (therefore its association with tumors of neuronal origin). Pathology Examples of tumors where these can be seen include: medulloblastoma (the presence of Homer Wright rosettes in a poster...

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