Monocytes are a type of leukocyte, or white blood cell. They are the largest type of leukocyte and can differentiate into macrophages and myeloid lineage dendritic cells; as a part of the vertebrate innate immune system monocytes influence the process of adaptive immunity. There are at least three subclasses of monocytes in human blood based on their phenotypic receptors. Monocytes are amoeboid in appearance, have nongranulated cytoplasm, thus are classified as agranulocytes. Containing unilobar nuclei, these cells are one of the types of mononuclear leukocytes which shelter azurophil granules; the archetypal geometry of the monocyte nucleus is ellipsoidal. Contrast to this classification occurs in polymorphonuclear leukocytes. Monocytes compose 2% to 10% of all leukocytes in the human body and serve multiple roles in immune function; such roles include: replenishing resident macrophages under normal conditions. In an adult human, half of the monocytes are stored in the spleen; these change into macrophages after entering into appropriate tissue spaces, can transform into foam cells in endothelium.
There are at least three types of monocytes in human blood: The classical monocyte is characterized by high level expression of the CD14 cell surface receptor The non-classical monocyte shows low level expression of CD14 and additional co-expression of the CD16 receptor. The intermediate monocyte with high level expression of CD14 and low level expression of CD16. While in humans the level of CD14 expression can be used to differentiate non-classical and intermediate monocytes, the slan cell surface marker was shown to give an unequivocal separation of the two cell types. Ghattas et al. state that the "intermediate" monocyte population is to be a unique subpopulation of monocytes, as opposed to a developmental step, due to their comparatively high expression of surface receptors involved in reparative processes as well as evidence that the "intermediate" subset is enriched in the bone marrow. After stimulation with microbial products the CD14+CD16++ monocytes produce high amounts of pro-inflammatory cytokines like tumor necrosis factor and interleukin-12.
Said et al. showed that activated monocytes express high levels of PD-1 which might explain the higher expression of PD-1 in CD14+CD16++ monocytes as compared to CD14++CD16- monocytes. Triggering monocytes-expressed PD-1 by its ligand PD-L1 induces IL-10 production which activates CD4 Th2 cells and inhibits CD4 Th1 cell function. In mice, monocytes can be divided in two subpopulations. Inflammatory monocytes, which are equivalent to human classical CD14++ CD16− monocytes and resident monocytes, which are equivalent to human non-classical CD14low CD16+ monocytes. Resident monocytes have the ability to patrol along the endothelium wall in the steady state and under inflammatory conditions. In humans a monocyte crawling behavior, similar to the patrolling in mice, has been demonstrated both for the classical and the non-classical monocytes. Monocytes are produced by the bone marrow from precursors called monoblasts, bipotent cells that differentiated from hematopoietic stem cells. Monocytes circulate in the bloodstream for about one to three days and typically move into tissues throughout the body where they differentiate into macrophages and dendritic cells.
They constitute between eight percent of the leukocytes in the blood. About half of the body's monocytes are stored as a reserve in the spleen in clusters in the red pulp's Cords of Billroth. Moreover, monocytes are the largest corpuscle in blood. Monocytes which migrate from the bloodstream to other tissues will differentiate into tissue resident macrophages or dendritic cells. Macrophages are responsible for protecting tissues from foreign substances, but are suspected to be important in the formation of important organs like the heart and brain, they are cells that possess a large smooth nucleus, a large area of cytoplasm, many internal vesicles for processing foreign material. In vitro, monocytes can differentiate into dendritic cells by adding the cytokines granulocyte macrophage colony-stimulating factor and interleukin 4. Monocytes and their macrophage and dendritic cell progeny serve three main functions in the immune system; these are phagocytosis, antigen presentation, cytokine production.
Phagocytosis is the process of uptake of microbes and particles followed by digestion and destruction of this material. Monocytes can perform phagocytosis using intermediary proteins such as antibodies or complement that coat the pathogen, as well as by binding to the microbe directly via pattern-recognition receptors that recognize pathogens. Monocytes are capable of killing infected host cells via antibody-dependent cell-mediated cytotoxicity. Vacuolization may be present in a cell that has phagocytized foreign matter. Many factors produced by other cells can regulate other functions of monocytes; these factors include most chemokines such as monocyte chemotactic protein-1 and monocyte chemotactic protein-3.
A bungee cord known as a shock cord - and in Australia, an occy strap or octopus strap - is an elastic cord composed of one or more elastic strands forming a core covered in a woven cotton or polypropylene sheath. The sheath does not materially extend elastically, but it is braided with its strands spiralling around the core so that a longitudinal pull causes it to squeeze the core, transmitting the core's elastic compression to the longitudinal extension of the sheath and cord. Specialized bungees, such as some used in bungee jumping, may be made of elastic strands. Bungee cords have been used to provide a lightweight suspension for aircraft undercarriages from before World War I, are still used on many small homebuilt aircraft where weight remains critical. Bungee cords were used in parachuting to assist in opening the old-style parachute container after the ripcord was pulled. Today, bungee cords are most used to secure objects without tying knots and to absorb shock. Inexpensive bungee cords, with metal or plastic hooks on each end, are marketed as a general utility item.
In Australia, this form is known as an "occy", strap. These can be an individual strap, or a set of four hooked straps held together by a metal ring allowing the occy strap to secure items around various tie points, for example a suitcase to a car roof rack. Extensions of the concept are available as a coarse net of bungee cords with metal or plastic hooks around the periphery, for securing irregularly shaped loads of luggage and cargo on the backs of pickup trucks, roofs of cars, so on. Bungee cords have been used to make bungee chairs and for other purposes; the origin of the name "bungee", "bungie" or "bungy" is uncertain. The Oxford English Dictionary records the use of the phrase in 1938 for launching of gliders using an elasticated cord. Bungee cords are a major source of eye injury, some doctors suggest not using them
Sarah Patricia Ann Caplin is a British producer and television executive at ITV, before that Deputy Secretary of the BBC, who has helped create two national charities, one for children and one for older people. She was a founder of Childline, together with her cousin Esther Rantzen and The Silver Line, she was educated at the University of York and has been married to TV presenter Nick Ross for more than twenty-five years. Caplin joined the BBC as a graduate trainee in 1980 and worked as a researcher on a variety of current affairs and factual entertainment programmes; as a producer her credits include ChildWatch, which involved the creation of a helpline, which in turn developed into ChildLine. Caplin was responsible for Drugwatch, which featured an appearance by the Princess of Wales as well as Crime The Shocking Truth and the pilot for Crimewatch. In 1989 she was appointed Editor of Watchdog, was responsible for hiring Anne Robinson as the presenter. In 1995 she was appointed Deputy Secretary of the BBC and in 1997 was headhunted to join Granada TV as the Editor of This Morning.
Caplin quit after three months because of what was reported as a difficult relationship with Judy Finnigan. She was promoted to head of development for Granada Factual North and in 2000 was appointed Head of Features. Among the shows she created are 60 Minute Makeover, several series with Jade Goody and the Royal Navy, House of Horrors. Caplin left ITV in March 2011 amid claims that she bullied members of staff although this ITV said her departure was part of a reorganisation of senior management. Caplin subsequently helped Esther Rantzen set up The Silver Line, a charity for older people, was Director of Policy and Communications. Sarah Caplin on IMDb