|
Clostridium Tetani
''Clostridium tetani'' is a common soil bacterium and the causative agent of tetanus. Vegetative cells of ''Clostridium tetani'' are usually rod-shaped and up to 2.5 μm long, but they become enlarged and tennis racket- or drumstick-shaped when forming spores. ''C. tetani'' spores are extremely hardy and can be found globally in soil or in the gastrointestinal tract of animals. If inoculated into a wound, ''C. tetani'' can grow and produce a potent toxin, tetanospasmin, which interferes with motor neurons, causing tetanus. The toxin's action can be prevented with tetanus toxoid vaccines, which are often administered to children worldwide. Characteristics ''Clostridium tetani'' is a rod-shaped, Gram-positive bacterium, typically up to 0.5 μm wide and 2.5 μm long. It is motile by way of various flagella that surround its body. ''C. tetani'' cannot grow in the presence of oxygen. It grows best at temperatures ranging from 33 to 37 °C. Upon exposure to various condi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carl Flügge
Carl Georg Friedrich Wilhelm Flügge (12 September 1847 – 10 December 1923) was a German bacteriologist and hygienist. His finding that pathogens were present in expiratory droplets, the eponymous Flügge droplets, laid the foundations for the concept of droplet transmission as a route for the spread of respiratory infectious diseases. Biography Originally from Hanover, Carl Georg Friedrich Wilhelm Flügge studied medicine in Göttingen, Bonn, Leipzig and Munich. In 1878 he taught hygiene in Berlin. In 1881 Flügge became the first chair of hygiene at the University of Göttingen, and afterwards was a professor at the Universities of Breslau and Berlin, where he succeeded Max Rubner (1854–1932) at the Department of Hygiene. Flügge was a colleague of microbiologist Robert Koch (1843–1910), with whom he co-edited the journal ''Zeitschrift für Hygiene und Infektionskrankheiten''. Two of his better-known assistants at Breslau were Wolfgang Weichardt (1875–1943) and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clostridium Difficile (bacteria)
''Clostridioides difficile'' ( syn. ''Clostridium difficile'') is a bacterium known for causing serious diarrheal infections, and may also cause colon cancer. It is known also as ''C. difficile'', or ''C. diff'' (), and is a Gram-positive species of spore-forming bacteria. ''Clostridioides'' spp. are anaerobic, motile bacteria, ubiquitous in nature and especially prevalent in soil. Its vegetative cells are rod-shaped, pleomorphic, and occur in pairs or short chains. Under the microscope, they appear as long, irregular (often drumstick- or spindle-shaped) cells with a bulge at their terminal ends (forms subterminal spores). Under Gram staining, ''C. difficile'' cells are Gram-positive and show optimum growth on blood agar at human body temperatures in the absence of oxygen. ''C. difficile'' is catalase- and superoxide dismutase-negative, and produces up to three types of toxins: enterotoxin A, cytotoxin B and Clostridioides difficile transferase. Under stress conditions, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motor Nerve
A motor nerve, or efferent nerve, is a nerve that contains exclusively efferent nerve fibers and transmits motor signals from the central nervous system (CNS) to the effector organs (muscles and glands), as opposed to sensory nerves, which transfer signals from sensory receptors in the periphery to the CNS. This is different from the motor neuron, which includes a cell body and branching of dendrites, while the nerve is made up of a bundle of axons. In the strict sense, a "motor nerve" can refer exclusively to the connection to muscles, excluding other organs. The vast majority of nerves contain both sensory and motor fibers and are therefore called mixed nerves. Structure and function Motor nerve fibers Transduction (physiology), transduce signals from the CNS to peripheral neurons of proximal muscle tissue. Motor nerve axon terminals innervate Skeletal muscle, skeletal and Smooth muscle tissue, smooth muscle, as they are heavily involved in muscle control. Motor nerves tend t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma-aminobutyric Acid
GABA (gamma-aminobutyric acid, γ-aminobutyric acid) is the chief inhibitory neurotransmitter in the developmentally mature mammalian central nervous system. Its principal role is reducing neuronal excitability throughout the nervous system. GABA is sold as a dietary supplement in many countries. It has been traditionally thought that exogenous GABA (i.e., taken as a supplement) does not cross the blood–brain barrier, but data obtained from more recent research (2010s) in rats describes the notion as being unclear. The carboxylate form of GABA is γ-aminobutyrate. Function Neurotransmitter Two general classes of GABA receptor are known: * GABAA receptor, GABAA in which the receptor is part of a ligand-gated ion channel complex * GABAB receptor, GABAB metabotropic receptors, which are G protein-coupled receptors that open or close ion channels via intermediaries (G proteins) Neurons that produce GABA as their output are called GABAergic neurons, and have chiefly inhibito ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycine
Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG (GGU, GGC, GGA, GGG). Glycine disrupts the formation of alpha-helices in secondary protein structure. Its small side chain causes it to favor random coils instead. Glycine is also an inhibitory neurotransmitter – interference with its release within the spinal cord (such as during a '' Clostridium tetani'' infection) can cause spastic paralysis due to uninhibited muscle contraction. It is the only achiral proteinogenic amino acid. It can fit into both hydrophilic and hydrophobic environments, due to its minimal side chain of only one hydrogen atom. History and etymology Glycine was discovered in 1820 by French chemist Henri Braconnot when he hydrolyzed gelatin by boiling it with sulfuric acid. He originally called it "sugar of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurotransmitter
A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a Chemical synapse, synapse. The cell receiving the signal, or target cell, may be another neuron, but could also be a gland or muscle cell. Neurotransmitters are released from synaptic vesicles into the synaptic cleft where they are able to interact with neurotransmitter receptors on the target cell. Some neurotransmitters are also stored in large dense core vesicles. The neurotransmitter's effect on the target cell is determined by the receptor it binds to. Many neurotransmitters are synthesized from simple and plentiful precursors such as amino acids, which are readily available and often require a small number of biosynthetic steps for conversion. Neurotransmitters are essential to the function of complex neural systems. The exact number of unique neurotransmitters in humans is unknown, but more than 100 have been identified. Common neurotransmitters include Glutamate (neurotransmi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nervous System
In biology, the nervous system is the complex system, highly complex part of an animal that coordinates its behavior, actions and sense, sensory information by transmitting action potential, signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. Nervous tissue first arose in Ediacara biota, wormlike organisms about 550 to 600 million years ago. In Vertebrate, vertebrates, it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers, or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor nerves (efferent), while those nerves that transmit information from the body to the CNS are called sensory nerves (aff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lymphatic System
The lymphatic system, or lymphoid system, is an organ system in vertebrates that is part of the immune system and complementary to the circulatory system. It consists of a large network of lymphatic vessels, lymph nodes, lymphoid organs, lymphatic tissue and lymph. Lymph is a clear fluid carried by the lymphatic vessels back to the heart for re-circulation. The Latin word for lymph, , refers to the deity of fresh water, "Lympha". Unlike the circulatory system that is a closed system, the lymphatic system is open. The human circulatory system processes an average of 20 litres of blood per day through Starling equation, capillary filtration, which removes blood plasma, plasma from the blood. Roughly 17 litres of the filtered blood is reabsorbed directly into the blood vessels, while the remaining three litres are left in the interstitial fluid. One of the main functions of the lymphatic system is to provide an accessory return route to the blood for the surplus three litres. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanogram
To help compare different ''Order of magnitude, orders of magnitude'', the following lists describe various ''mass'' levels between 10−67 kilogram, kg and 1052 kg. The least massive thing listed here is a graviton, and the most massive thing is the Mass of the observable universe, observable universe. Typically, an object having greater mass will also have greater weight (see mass versus weight), especially if the objects are subject to the same gravitational field, gravitational field strength. Units of mass The table at right is based on the kilogram (kg), the base unit of mass in the International System of Units (SI). The kilogram is the only standard unit to include an SI prefix (''kilo-'') as part of its name. The ''gram'' (10−3 kg) is an SI derived unit of mass. However, the ''names'' of all SI mass units are based on ''gram'', rather than on ''kilogram''; thus 103 kg is a ''megagram'' (106 g), not a *''kilokilogram''. The ''tonne'' (t) is an SI-compatible u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetanolysin
Tetanolysin is a toxin produced by '' Clostridium tetani'' bacteria. Its function is unknown, but it is believed to contribute to the pathogenesis of tetanus. The other ''C. tetani'' toxin, tetanospasmin, is more definitively linked to tetanus. It is sensitive to oxygen. Tetanolysin belongs to a family of protein toxins known as thiol-activated cytolysins, which bind to cholesterol. It is related to streptolysin O and the θ-toxin of ''Clostridium perfringens''. Cytolysins form pores in the cytoplasmic membrane that allows for the passage of ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...s and other molecules into the cell. The molecular weight of tetanolysin is around 55,000 daltons. References Further reading *Alouf, J. (1997) pp 7–10 in ''Guidebook to Protein T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exotoxin
An exotoxin is a toxin secreted by bacteria. An exotoxin can cause damage to the host by destroying cells or disrupting normal cellular metabolism. They are highly potent and can cause major damage to the host. Exotoxins may be secreted, or, similar to endotoxins, may be released during lysis of the cell. Gram negative pathogens may secrete outer membrane vesicles containing lipopolysaccharide endotoxin and some virulence proteins in the bounding membrane along with some other toxins as intra-vesicular contents, thus adding a previously unforeseen dimension to the well-known eukaryote process of membrane vesicle trafficking, which is quite active at the host–pathogen interface. They may exert their effect locally or produce systemic effects. Well-known exotoxins include: botulinum toxin produced by ''Clostridium botulinum''; ''Corynebacterium diphtheriae'' toxin, produced during life-threatening symptoms of diphtheria; tetanospasmin produced by '' Clostridium tetani''. The t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
