Reptiles produce venom to facilitate immobilization and digestion of prey or as defence mechanism against threats. Snake venom is complex mixtures of pharmacologically active proteins and polypeptides interfering with vital physiological systems.도마뱀분양
Venom is either injected by a modified parotid gland during a bite or spitted when irritated. Snakes in the family Viperidae (vipers and saw-scaled vipers) can spit streams of venom up to 8 ft.
The nervous system is a complex network of cells that transmits information between other cells and organs, and controls motor functions usually in response to sensory input from the environment. It also carries out complex thought processes, memory and sensations. Hence, it can be vulnerable to toxicants. Neurotoxic chemicals are substances that damage or destroy nerve tissue.
Many different chemical compounds can have a neurotoxic effect, including snake venom, pesticides, heroin and alcohol. However, a specific group of chemicals called neurotoxins can cause paralysis and are particularly damaging to nerve cell function. 도마뱀분양
These neurotoxins work by attacking parts of the nervous system whose complete functionality is essential for survival. They bind to the nerve cell surface, blocking or altering the movement of ions across the membrane. In particular, they affect the ion channels responsible for neurotransmitter release.
In addition, some neurotoxins deliver inside their target neurons a metalloprotease that cleaves one copy after the other of proteins required for neurotransmitter release. It is this neurospecificity, the cellular dependence of the targeted neurons on functional neurotransmitters and their importance for survival that make these neurotoxins the most effective poisons known to humans.
Tetanus and botulinum neurotoxins have been made less potent by the development of polyclonal and monoclonal antibodies. The antibodies bind to the neurotoxins and prevent their binding to neurons, thus neutralizing their 도마뱀분양 activity. However, these drugs only work if they are administered before symptoms of tetanus or botulism appear.
While cytotoxins damage cells, haemotoxins disrupt the blood’s ability to clot. Snake venoms contain a range of these compounds that cause internal bleeding, including nose and mouth bleeds, bleeding at the bite site, genitourinary and gastrointestinal tracts (haematemesis, haemoptysis) and blood in the urine and faeces (haemorrhage).
Hemotoxins work by causing the breakdown of red blood cells, making blood too thin to clot and preventing clotting at the wound site. Generally, vipers favour hemotoxins – such as venom from Russell’s viper (Daboia russellii) shown here – that target the circulatory system, causing swelling and loss of blood pressure.
These chemicals are a vital tool for snakes to capture prey but can be lethal in humans, who often suffer haemorrhagic and/or coagulopathic pathology following snakebite (Fig 1). Having evolved via gene duplication events and lineage-specific toxin loss, each species of snake has many different haemotoxic toxins.
These compounds work by depleting platelets, thereby inducing a variety of coagulopathies that present clinically as hypocoagulability (Fig 2). This type of venom is associated with bleeding at the bite site, peri-oral and oral mucosa, gastro-intestinal and genitourinary tracts and haematemesis and haemoptysis. Some SVMPs also have fibrinogenolytic activity and inhibit clotting factors, such as Factor V and prothrombin. This venom type is associated with the most severe haemorrhage and requires urgent treatment to minimise complications, particularly renal failure from hyper-filtration.
Mycotoxins are natural metabolites produced by fungal organisms that cause mycotoxicoses in animals and humans. They occur worldwide but are most common in climates with high temperatures and humidity, or where grain is exposed to excessive moisture. Mycotoxins are widespread and cause significant economic loss. The problem affects animal welfare and human health, with some toxins having a carcinogenic effect on the host.
Signs and symptoms of mycotoxin toxicity vary depending on the specific mycotoxin. Aflatoxins, for example, lead to a reduced feed intake and body weight loss, diarrhea, vomiting and changes in gut microflora. Zearalenone (ZEN) leads to kidney and liver damage, gastrointestinal lesions, a hunched stance in calves, uterus inflammation, abortions and delayed sexual maturation in females and decreased milk production in dairy cattle. Ochratoxins produced by Aspergillus ochraceus interfere with the function of kidney, proventriculus and gizzard in poultry; rubratoxin A produced by Penicillium species is toxic to birds and is related to thiamine deficiency.
Glial cytotoxicity caused by mycotoxins leads to activation of the innate immune system, which in turn activates inflammatory cascades that lead to a vicious cycle of cellular damage and autoimmunity. These findings suggest that glial cells may be an important target for mycotoxin-mediated neuroinflammation. The best way to avoid mycotoxins is to follow the HACCP food safety system, which consists of analysis, control and monitoring of physical, chemical and biological hazards during raw material manufacturing, storage, transportation, production, distribution and consumption of foods.
Snake venoms are highly complex mixtures of pharmacologically active proteins and polypeptides that interfere in vital physiological systems. They include hemotoxins that act on the blood and cardiovascular system, neurotoxic toxins that impair the somatic nervous system (PNS), and cytotoxic toxins with local action at the bite site. Snake venom paralytic neurotoxins compete with the natural neurotransmitter acetylcholine to block nerve-muscle transmission, resulting in muscle weakness or paralysis. They also act at the presynaptic terminal by interacting with the enzyme phospholipase A2 (PLA2) to inhibit its activity. Clinically relevant snake venom neurotoxins can be divided into two groups based on their pharmacologic effects: those that depolarize the postsynaptic membrane and those that do not.
The most lethal part of snake venom is the neurotoxic component, which can paralyse a person starting in the head and moving down the body until, if untreated, it reaches the diaphragm and prevents breathing. However, if treated quickly enough with the right drugs, patients can be saved.
The first thing to do when bitten by a dangerous snake is to irrigate the bitten area thoroughly with large volumes of water. This helps to prevent blindness caused by the venom spraying into the eyes from some elapids such as king cobras and spitting cobras. Next, apply a pressure immobilisation bandage to the limb that has been bitten. This is best done with a heavy crepe or elasticised roller bandage.