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Phoneutria Nigriventer
''Phoneutria nigriventer'' is a species of Medically significant spider bites, medically significant spider in the family Ctenidae, found in the Southern Cone of South America (Brazil, Uruguay, Paraguay, and Argentina). Along with other members of the genus, they are often referred to as Brazilian wandering spiders. Its bite can cause severe symptoms, including extraordinary pain, increased pulse, blood pressure, and respiratory rate, penile erection (priapism) that lasts for several hours, and in Phoneutria#Reported_cases, several documented cases, death.Natural Viagra: Spider bite causes prolonged erection ''Live Science'', April 30, 2007. Accessed July 9, 2019. Description and behavior ''Phoneutria nigriventer'' is a large spider. Its maximum body ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eugen Von Keyserling
Eugen von Keyserling (22 March 1833 in Pockroy, Lithuania – 4 April 1889 in Dzierżoniów, Silesia) was a Baltic-German arachnologist. He studied in the University of Tartu. He was the author of ''Die Spinnen Amerikas'', and completed ''Die Arachniden Australiens'' (1871–1883) on behalf of Ludwig Carl Christian Koch Ludwig Carl Christian Koch (8 November 1825 – 1 November 1908) was a German entomologist and arachnologist. He was born in Regensburg, Germany, and died in Nuremberg, Germany. He studied in Nuremberg, initially law, but then turned to medic .... External links * German arachnologists University of Tartu alumni People from Pakruojis Baltic-German people 1833 births 1889 deaths 19th-century German zoologists {{germany-zoologist-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcium Channel
A calcium channel is an ion channel which shows selective permeability to calcium ions. It is sometimes synonymous with voltage-gated calcium channel, although there are also ligand-gated calcium channels. Comparison tables The following tables explain gating, gene, location and function of different types of calcium channels, both voltage and ligand-gated. Voltage-gated Ligand-gated *the ''receptor-operated calcium channels'' (in vasoconstriction) **P2X receptors Page 479 Pharmacology L-type calcium channel blockers are used to treat hypertension. In most areas of the body, depolarization is mediated by sodium influx into a cell; changing the calcium permeability has little effect on action potentials. However, in many smooth muscle tissues, depolarization is mediated primarily by calcium influx into the cell. L-type calcium channel blockers selectively inhibit these action potentials in smooth muscle which leads to dilation of blood vessels; this in turn corrects hypert ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tx2-6
Tx2-6 is a toxin found in the venom of the Brazilian wandering spider, '' Phoneutria nigriventer'' (Keyserling). It is a peptide of 48 residues, molecular weight 5291.3. This peptide is cleaved from a longer precursor with a signal peptide and a glutamine-rich propeptide. It can cause priapism. Tests on rats indicate that the toxin causes nitric oxide release, and its effect on erection is blocked by the nitric oxide synthase inhibitor L-NAME. However, it fully restored erectile function in rats developing hypertension due to injection of deoxycorticosterone acetate. A study is underway at the Medical College of Georgia looking at possible uses for the chemical in erectile dysfunction medication. Scientists and Gregory Ochs (Dobbs 2) are collaborating on this study. See also *Pharmacology *Spiders Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PhTx-2
PhTx-2 is a toxic fraction of the venom of the Brazilian wandering spider '' Phoneutria nigriventer''. Target This fraction is responsible for most of the venom's effects, acts on voltage-gated ion channels, this fraction is composed of nine different peptides, of which PhTx-2-5 and PhTx-2-6 activate voltage-gated ion channels. PhTx-2 has been shown to be related to the activation and delay of inactivation of neuronal sodium channels, leading to an increase in the concentration of neuronal Ca++ and the release of glutamate, resulting in the release of neurotransmitters such as acetylcholine and catecholamines.{{Cite book, last1=Weiss, first1=Marcelo Barros, url=https://books.google.com/books?id=NzlyDwAAQBAJ&q=PhTx-2+convuls%C3%B5es+paralisias&pg=PT161, title=Acidentes com Animais Peçonhentos, last2=Paiva, first2=Jorge Wilson Souza, date=2018-10-10, publisher=Thieme Revinter Publicações LTDA, isbn=978-85-5465-084-1, language=pt-BR Primates are more sensitive to the PhTx-1 & 2 co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Median Lethal Dose
In toxicology, the median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a toxin, radiation, or pathogen. The value of LD50 for a substance is the dose required to kill half the members of a tested population after a specified test duration. LD50 figures are frequently used as a general indicator of a substance's acute toxicity. A lower LD50 is indicative of increased toxicity. The test was created by J.W. Trevan in 1927. The term semilethal dose is occasionally used in the same sense, in particular with translations of foreign language text, but can also refer to a sublethal dose. LD50 is usually determined by tests on animals such as laboratory mice. In 2011, the U.S. Food and Drug Administration approved alternative methods to LD50 for testing the cosmetic drug Botox without animal tests. Conventions The LD50 is usually expressed as the mass of substance administered per unit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substance P
Substance P (SP) is an undecapeptide (a peptide composed of a chain of 11 amino acid residues) and a member of the tachykinin neuropeptide family. It is a neuropeptide, acting as a neurotransmitter and as a neuromodulator. Substance P and its closely related neurokinin A (NKA) are produced from a polyprotein precursor after differential splicing of the preprotachykinin A gene. The deduced amino acid sequence of substance P is as follows: * Arg Pro Lys Pro Gln Gln Phe Phe Gly Leu Met (RPKPQQFFGLM) with an amidation at the C-terminus. Substance P is released from the terminals of specific sensory nerves. It is found in the brain and spinal cord and is associated with inflammatory processes and pain. Discovery The original discovery of Substance P (SP) was in 1931 by Ulf von Euler and John H. Gaddum as a tissue extract that caused intestinal contraction ''in vitro''. Its tissue distribution and biologic actions were further investigated over the following decades. The ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuropeptides
Neuropeptides are chemical messengers made up of small chains of amino acids that are synthesized and released by neurons. Neuropeptides typically bind to G protein-coupled receptors (GPCRs) to modulate neural activity and other tissues like the gut, muscles, and heart. There are over 100 known neuropeptides, representing the largest and most diverse class of signaling molecules in the nervous system. Neuropeptides are synthesized from large precursor proteins which are cleaved and post-translationally processed then packaged into dense core vesicles. Neuropeptides are often co-released with other neuropeptides and neurotransmitters in a single neuron, yielding a multitude of effects. Once released, neuropeptides can diffuse widely to affect a broad range of targets. Synthesis Neuropeptides are synthesized from large, inactive precursor proteins called prepropeptides. Prepropeptides contain sequences for a family of distinct peptides and often contain repeated copies of the sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
5-HT4 Receptor
5-Hydroxytryptamine receptor 4 is a protein that in humans is encoded by the ''HTR4'' gene. Function This gene is a member of the family of human serotonin receptors, which are G protein-coupled receptors that stimulate cAMP production in response to serotonin (5-hydroxytryptamine). The gene product is a glycosylated transmembrane protein that functions in both the peripheral and central nervous system to modulate the release of various neurotransmitters. Multiple transcript variants encoding proteins with distinct C-terminal sequences have been described, but the full-length nature of some transcript variants has not been determined. Location The receptor is located in the alimentary tract, urinary bladder, heart and adrenal gland as well as the central nervous system (CNS). In the CNS the receptor appears in the putamen, caudate nucleus, nucleus accumbens, globus pallidus, and substantia nigra, and to a lesser extent in the neocortex, raphe, pontine nuclei, and some area ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serotonin
Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vasoconstriction. Approximately 90% of the serotonin that the body produces is in the intestinal tract. Biochemically, the indoleamine molecule derives from the amino acid tryptophan, via the (rate-limiting) hydroxylation of the 5 position on the ring (forming the intermediate 5-hydroxytryptophan), and then decarboxylation to produce serotonin. Serotonin is primarily found in the enteric nervous system located in the gastrointestinal tract (GI tract). However, it is also produced in the central nervous system (CNS), specifically in the raphe nuclei located in the brainstem, Merkel cells located in the skin, pulmonary neuroendocrine cells and taste receptor cells in the tongue. Additionally, serotonin is stored in blood platelets and is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inflammation
Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving immune cells, blood vessels, and molecular mediators. The function of inflammation is to eliminate the initial cause of cell injury, clear out necrotic cells and tissues damaged from the original insult and the inflammatory process, and initiate tissue repair. The five cardinal signs are heat, pain, redness, swelling, and Functio laesa, loss of function (Latin ''calor'', ''dolor'', ''rubor'', ''tumor'', and ''functio laesa''). Inflammation is a generic response, and therefore it is considered as a mechanism of innate immune system, innate immunity, as compared to adaptive immune system, adaptive immunity, which is specific for each pathogen. Too little inflammation could lead to progressive tissue destruction by the harmful stimulus (e.g. b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asphyxiation
Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that can induce asphyxia, all of which are characterized by the inability of a person to acquire sufficient oxygen through breathing for an extended period of time. Asphyxia can cause coma or death. In 2015, about 9.8 million cases of unintentional suffocation occurred which resulted in 35,600 deaths. The word asphyxia is from Ancient Greek "without" and , "squeeze" (throb of heart). Causes Situations that can cause asphyxia include but are not limited to: airway obstruction, the constriction or obstruction of airways, such as from asthma, laryngospasm, or simple blockage from the presence of foreign materials; from being in environments where oxygen is not readily accessible: such as underwater, in a low oxygen atmosphere, or in a vacuum; envir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
