Spring til indhold

Bruger:Sasha/Kladde1

Fra Wikipedia, den frie encyklopædi
FIV
FIV-protease
FIV-protease
Videnskabelig klassifikation
DomæneVira (Virus)
(urangeret)Gruppe VI (ssRNA-RT)
FamilieRetroviridae (Retrovirus)
SlægtLentivirus
Hjælp til læsning af taksobokse

FIV (felin immundefektvirus) er en lentivirus, der påvirker tamme huskatte over hele verden og er den virus, der forårsager katteaids. Ca. 11%[1] af katte på verdensplan, og omkring 2,5% af alle katte i USA[2] er inficeret med FIV. FIV adskiller taxonomisk fra to andre katte-retrovira, felin leukæmi-virus (FeLV) og katteskummende virus (FFV), og er mere tæt forbundet med human immundefektvirus (HIV). FIV har fem undertyper (der er identificeret), som baseret på nukleotidsekvens-forskelle, der koder for den virale envelop (ENV) eller polymerase (POL). FIV er den eneste ikke-primatær lentivirus, der forårsager en AIDS-lignende syndrom, men FIV giver ikke altid en dødsdom til katte; de kan leve forholdsvis sundt som bærere og sendere af sygdommen i mange år. Der findes en vaccine, selv om dens effekt er fortsat usikker, og katte vil blive testet positiv for FIV-antistoffer efter vaccination.

FIV blev først opdaget i 1986 i en koloni af katte, der havde en høj forekomst af opportunistiske infektioner og degenerative betingelser, og er siden blevet identificeret som en endemisk sygdom i huskatte, gældende for hele verden[2].

Transmission

The primary modes of FIV transmission are deep bite wounds and scratches, where the infected cat's saliva enters the other cat's bloodstream. FIV may also be transmitted from pregnant females to their offspring in utero.[3] This differs from FeLV, which may be spread by more casual, non-aggressive contact since the virus is also present at mucosal surfaces such as those in the mouth, rectum, and vagina, so casual contact cannot be ruled out as a potential transmission.

Testing

Veterinarians will check a cat's history, look for clinical signs, and possibly administer a blood test for FIV antibodies. FIV affects 2-3% of cats in the US and testing is readily available. It should be noted that this testing identifies those cats that carry the FIV antibody, and does not detect the actual virus. Therefore, a positive test does not necessarily mean the cat is a carrier of FIV.

False positives occur when the cat carries the antibody (which is harmless), but does not carry the actual virus. The most frequent occurrence of this is when kittens are tested after ingesting the antibodies from mother's milk, and when testing cats that have been previously vaccinated for FIV. For this reason, neither kittens under 8 weeks, nor cats that have been previously vaccinated are tested.

Kittens and young cats that test positive for the FIV antibody may test negative at a later time due to seroreversion, provided they have never been infected with FIV and have never been immunized with the FIV vaccine.

Cats that have been vaccinated will test positive for the FIV antibody for the rest of their life due to seroconversion, even though they are not infected. Therefore, testing of strays or adopted cats is inconclusive, since it is impossible to know whether or not they have been vaccinated in the past. For these reasons, a positive FIV antibody test by itself should never be used as criteria for euthanasia.[kilde mangler]

Tests can be performed in a vet's office with results in minutes, allowing for quick consultation. Early detection helps maintain the cat's health and prevents spreading infection to other cats. With proper care, infected cats can live long and healthy lives.

Vaccine

A vaccine for FIV is available (ATCvet code: Skabelon:ATCvet), and was developed using isolates of two of the five FIV subtypes (or clades): A and D.[4] The vaccine was shown to be moderately protective (82% of cats were protected) against subtype A FIV,[5] but a later study showed it to offer no protection against subtype A.[6] It has shown 100% effectiveness against two different subtype B FIV strains.[7][8] Vaccination will cause cats to have positive results on FIV tests, making diagnosis more difficult. For these reasons the vaccine is considered "non-core", and the decision to vaccinate should be made after discussion with a veterinarian and consideration of the risks vs. the effectiveness.[9]

Approved treatment

In 2006, the United States Department of Agriculture issued a conditional license for a new treatment aid termed Lymphocyte T-Cell Immune Modulator.[10] Lymphocyte T-Cell Immune Modulator is manufactured by T-Cyte Therapeutics, Inc., exclusively licensed by IMULAN BioTherapeutics, LLC and distributed in the United States by ProLabs Animal Health (www.prolabsanimalhealth.com). However, thus far, only one trial has been published in a reputable veterinary journal, and that trial consisted of only about half a dozen cats. At this time, rigorous clinical trials have yet to be conducted and published. The cost of obtaining the treatment aid is very high and its efficacy is often disappointing in individual cases.

Lymphocyte T-Cell Immune Modulator is intended as an aid in the treatment of cats infected with feline leukemia virus (FeLV) and/or feline immunodeficiency virus (FIV), and the associated symptoms of lymphocytopenia, opportunistic infection, anemia, granulocytopenia, or thrombocytopenia. The absence of any observed adverse events in several animal species, suggests that the product has a very low toxicity profile.

Lymphocyte T-Cell Immune Modulator is a potent regulator of CD-4 lymphocyte production and function.[11] It has been shown to increase lymphocyte numbers and Interleukin 2 production in animals.[12]

Lymphocyte T-Cell Immune Modulator is a single chain polypeptide. It is a strongly cationic glycoprotein, and is purified with cation exchange resin. Purification of protein from bovine-derived stromal cell supernatants produces a substantially homogeneous factor, free of extraneous materials. The bovine protein is homologous with other mammalian species and is a homogeneous 50 kDa glycoprotein with an isoelectric point of 6.5. The protein is prepared in a lyophilized 1 microgram dose. Reconstitution in sterile diluent produces a solution for subcutaneous injection.[13]

Effects

FIV can attack the immune system of cats, much like the human immunodeficiency virus (HIV) can attack the immune system of human beings. FIV infects many cell types in its host, including CD4+ and CD8+ T lymphocytes, B lymphocytes, and macrophages. FIV can be tolerated well by cats, but can eventually lead to debilitation of the immune system in its feline hosts by the infection and exhaustion of T-helper (CD4+) cells.

FIV and HIV are both lentiviruses; however, neither can infect the other's usual host: humans cannot be infected by FIV nor can cats be infected by HIV. FIV is transmitted primarily through saliva (bites), such as those incurred during territorial battles between males. Cats housed exclusively indoors are much less likely to be infected, provided they do not come in contact with infected cats.

Consensus whether there is a need to euthanize FIV infected cats has not been established. The American Associations of Feline Practitioners, as well as many feral cat organizations, recommend against euthanizing FIV+ cats, or even spending funds to test for the virus, as spaying or neutering cats seems to effectively control transmission - as neutered cats are less likely to engage in territorial fights. A vigilant pet owner who treats secondary infections can assist an infected cat to live a reasonably long life. The chance that an FIV infected cat will pass the disease on to other cats within a household remains, and increases with serious fighting or biting (American Association of Feline Practitioners 2002). There is a quantifiable risk that cats living outside of a home can spread the disease to others and can also spread the disease in a group setting in a shelter. Cats living alone as a single pet, rarely left to roam free, pose a diminished, but not non-existent risk.

The disease occurs in three stages: First is the Acute Stage (1–2 months after transmission) in which fever, depression, and generalized lymphadenopathy are observed (Wise 2005). Second is the Subclinical Stage (4 weeks to X months after transmission), in which symptoms of the disease decrease or disappear; however, all cats remain viremic for life. Third is the Chronic Stage, in which cats eventually succumb to chronic infections due to suppressed immune system function. Cats may incur stomatitis, odontoclasia, periodontitis, gingivitis, rhinitis, conjunctivitis, pneumonitis, enteritis, and dermatitis in the later stages of infection. FIV+ cats are less likely to develop AIDS-like symptoms than HIV+ humans.

FIV infects other feline species, and in fact is endemic in some large wild cats, such as African lions. Unlike domestic cats, these species do not necessarily exhibit symptoms, perhaps because they have developed evolutionary mutations that confer resistance.

See also

References

  1. ^ Richards, J (2005). "Felin immundefektvirus-vaccine: Implikationer for diagnosticering og sygdomsbehandling". Biologicals. 33: 215. doi:10.1016/j.biologicals.2005.08.004.
  2. ^ a b Zislin, A (2005). "Felin immundefektvirus-vaccine: En rationel paradigme for kliniske beslutningsprocesser". Biologicals. 33: 219. doi:10.1016/j.biologicals.2005.08.012.
  3. ^ American Association of Feline Practitioners (2002). "Feline Immunodeficiency Virus". Cornell Feline Health Center. Cornell University, College of Veterinary Medicine. Hentet 2008-11-12.
  4. ^ Levy, J (2008), "2008 American Association of Feline Practitioners' feline retrovirus management guidelines", Journal of Feline Medicine & Surgery, 10: 300, doi:10.1016/j.jfms.2008.03.002
  5. ^ Huang, C.; Conlee, D.; Loop, J.; Champ, D.; Gill, M.; Chu, H.J. (2004), "Efficacy and safety of a feline immunodeficiency virus vaccine", Animal Health Research Reviews, 5: 295-300, doi:10.1079/AHR200487
  6. ^ Dunham, S.P.; Bruce, J.; Mackay, S.; Golder, M.; Jarrett, O.; Neil, J.C. (2006), "Limited efficacy of an inactivated feline immunodeficiency virus vaccine.", Veterinary Record, 158: 561-562
  7. ^ Kusuhara, H.; Hohdatsu, T.; Okumura, M.; Sato, K.; Suzuki, Y.; Motokawa, K.; Gemma, T.; Watanabe, R.; Huang, C.; Arai, S.; Koyama, H. (2005), "Dual-subtype vaccine (Fel-O-Vax FIV) protects cats against contact challenge with heterologous subtype B FIV infected cats.", Veterinary Microbiology, 108: 155-165, doi:10.1016/j.vetmic.2005.02.014
  8. ^ Pu, R.; Coleman, J.; Coisman, J.; Sato, E.; Tanabe, T.; Arai, M.; Yamamoto, JK. (2005), "Dual-subtype FIV vaccine (Fel-O-Vax FIV) protection against a heterologous subtype B FIV isolate.", Journal of Feline Medicine and Surgery, 7: 65-70, doi:10.1016/j.jfms.2004.08.005
  9. ^ Levy, J (2008), "2008 American Association of Feline Practitioners' feline retrovirus management guidelines", Journal of Feline Medicine & Surgery, 10: 300-316, doi:10.1016/j.jfms.2008.03.002
  10. ^ United States Department of Agriculture. Veterinary Biological Products; Licensees and Permittees, December 2006.
  11. ^ Beardsley, et al. "Induction of T-Cell Maturation by a Cloned Line of Thymic Epithelium (TEPI) Immunology 80: pp. 6005-6009, (Oct. 1983).
  12. ^ Skabelon:Ref patent
  13. ^ Skabelon:Ref patent

Kategori:Vira]] Kategori:HIV/AIDS]]



Radiokemi er kemien i radioaktivt materiale, hvor de radioaktive isotoper af elementer bruges til at undersøge de egenskaber og kemiske reaktioner af ikke-radioaktive isotoper (ofte inden radiokemi, mangel af radioaktivitet fører til et stof, der beskrives som værende inaktiv som stabile isotoper). Meget af radiokemibygningen omhandler brugen af radioaktivitet til at studere almindelige kemiske reaktioner.

Radiokemi omfatter undersøgelse af både naturlige og menneskeskabte radioaktive isotoper.

Main decay modes

All radioisotopes are unstable isotopes of elements—undergo nuclear decay and emit some form of radiation. The radiation emitted can be one of three types, called alpha, beta, or gamma radiation.

1. α (alpha) radiation - the emission of an alpha particle (which contains 2 protons and 2 neutrons) from an atomic nucleus. When this occurs, the atom’s atomic mass will decrease by 4 units and atomic number will decrease by 2.

2. β (beta) radiation - the transmutation of a neutron into an electron and a proton. After this happens, the electron is emitted from the nucleus into the electron cloud.

3. gamma radiation - the emission of electromagnetic energy (such as X-rays) from the nucleus of an atom. This usually occurs during alpha or beta radioactive decay.

These three types of radiation can be distinguished by their difference in penetrating power.

Alpha can be stopped quite easily by a few centimetres in air or a piece of paper and is equivalent to a helium nucleus. Beta can be cut off by an aluminium sheet just a few millimetres thick and are electrons. Gamma is the most penetrating of the three and is a massless chargeless high energy photon. Gamma radiation requires an appreciable amount of heavy metal radiation shielding (usually lead or barium-based) to reduce its intensity.

Activation analysis

By neutron irradiation of objects it is possible to induce radioactivity; this activation of stable isotopes to create radioisotopes is the basis of neutron activation analysis. One of the most interesting objects which has been studied in this way is the hair of Napoleon's head, which have been examined for their arsenic content.[1]

A series of different experimental methods exist, these have been designed to enable the measurement of a range of different elements in different matrices. To reduce the effect of the matrix it is common to use the chemical extraction of the wanted element and/or to allow the radioactivity due to the matrix elements to decay before the measurement of the radioactivity. Since the matrix effect can be corrected for by observing the decay spectrum, little or no sample preparation is required for some samples, making neutron activation analysis less susceptible to contamination.

The effects of a series of different cooling times can be seen if a hypothetical sample which contains sodium, uranium and cobalt in a 100:10:1 ratio was subjected to a very short pulse of thermal neutrons. The initial radioactivity would be dominated by the 24Na activity (half-life 15 h) but with increasing time the 239Np (half-life 2.4 d after formation from parent 239U with half-life 24 min) and finally the 60Co activity (5.3 yr) would predominate.

Biochemical uses

One biological application is the study of DNA using radioactive phosphorus-32. In these experiments stable phosphorus is replaced by the chemical identical radioactive P-32, and the resulting radioactivity is used in analysis of the molecules and their behaviour.

Another example is the work which was done on the methylation of elements such as sulfur, selenium, tellurium and polonium by living organisms. It has been shown that bacteria can convert these elements into volatile compounds,[2] it is thought that methylcobalamin (vitamin B12) alkylates these elements to create the dimethyls. It has been shown that a combination of Cobaloxime and inorganic polonium in sterile water forms a volatile polonium compound, while a control experiment which did not contain the cobalt compound did not form the volatile polonium compound.[3] For the sulfur work the isotope 35S was used, while for polonium 207Po was used. In some related work by the addition of 57Co to the bacterial culture, followed by isolation of the cobalamin from the bacteria (and the measurement of the radioactivity of the isolated cobalamin) it was shown that the bacteria convert available cobalt into methylcobalamin.

Environmental

Radiochemistry also includes the study of the behaviour of radioisotopes in the environment; for instance, a forest or grass fire can make radioisotopes become mobile again.[4] In these experiments, fires were started in the exclusion zone around Chernobyl and the radioactivity in the air downwind was measured.

It is important to note that a vast number of processes are able to release radioactivity into the environment, for example the action of cosmic rays on the air is responsible for the formation of radioisotopes (such as 14C and 32P), the decay of 226Ra forms 222Rn which is a gas which can diffuse through rocks before entering buildings[5][6][7] and dissolve in water and thus enter drinking water[8] in addition human activities such as bomb tests, accidents,[9] and normal releases from industry have resulted in the release of radioactivity.

Chemical form of the actinides

The environmental chemistry of some radioactive elements such as plutonium is complicated by the fact that solutions of this element can undergo disproportionation[10] and as a result many different oxidation states can coexist at once. Some work has been done on the identification of the oxidation state and coordination number of plutonium and the other actinides under different conditions has been done.[2] This includes work on both solutions of relatively simple complexes[11][12] and work on colloids[13] Two of the key matrixes are soil/rocks and concrete, in these systems the chemical properties of plutonium have been studied using methods such as EXAFS and XANES.[14][3][4]

Movement of colloids

While binding of a metal to the surfaces of the soil particles can prevent its movement through a layer of soil, it is possible for the particles of soil which bear the radioactive metal can migrate as colloidal particles through soil. This has been shown to occur using soil particles labeled with 134Cs, these have been shown to be able to move through cracks in the soil.[15]

Normal background

Radioactivity is present everywhere (and has been since the formation of the earth). According to the International Atomic Energy Agency, one kilogram of soil typically contains the following amounts of the following three natural radioisotopes 370 Bq 40K (typical range 100-700 Bq), 25 Bq 226Ra (typical range 10-50 Bq), 25 Bq 238U (typical range 10-50 Bq) and 25 Bq 232Th (typical range 7-50 Bq).[16]

Action of microorganisms

The action of micro-organisms can fix uranium; Thermoanaerobacter can use chromium(VI), iron(III), cobalt(III), manganese(IV) and uranium(VI) as electron acceptors while acetate, glucose, hydrogen, lactate, pyruvate, succinate, and xylose can act as electron donors for the metabolism of the bacteria. In this way the metals can be reduced to form magnetite (Fe3O4), siderite (FeCO3), rhodochrosite (MnCO3), and uraninite (UO2).[17] Other researchers have also worked on the fixing of uranium using bacteria[5][6][7], Francis R. Livens et al. (Working at Manchester) have suggested that the reason why Geobacter sulfurreducens can reduce UO22+ cations to uranium dioxide is that the bacteria reduce the uranyl cations to UO2+ which then undergoes disproportionation to form UO22+ and UO2. This reasoning was based (at least in part) on the observation that NpO2+ is not converted to an insoluble neptunium oxide by the bacteria.[18]

References

  1. ^ H. SMITH, S. FORSHUFVUD & A. WASSÉN, Nature, 1962, 194(26 May), 725-726
  2. ^ N. Momoshima, Li-X. Song, S. Osaki and Y. Maeda, "Biologically induced Po emission from fresh water", Journal of Environmental Radioactivity, 2002, 63, 187-197
  3. ^ N. Momoshima, Li-X. Song, S. Osaki and Y. Maeda, "Formation and emission of volatile polonium compound by microbial activity and polonium methylation with methylcobalamin", Environmental Science and Technology, 2001, 35, 2956-2960
  4. ^ Yoschenko VI et al. (2006) Resuspension and redistribution of radionuclides during grassland and forest fires in the Chernobyl exclusion zone: part I. Fire experiments J Envir Radioact 86:143-63 PMID 16213067
  5. ^ Janja Vaupotič and Ivan Kobal, "Effective doses in schools based on nanosize radon progeny aerosols", Atmospheric Environment, 2006, 40, 7494-7507
  6. ^ Michael Durand, Building and Environment, "Indoor air pollution caused by geothermal gases", 2006, 41, 1607-1610
  7. ^ Paolo Boffetta, "Human cancer from environmental pollutants: The epidemiological evidence", Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 2006, 608, 157-162
  8. ^ M. Forte, R. Rusconi, M.T. Cazzaniga and G. Sgorbati, "The measurement of radioactivity in Italian drinking waters", Microchemical Journal, 2007, 85, 98-102
  9. ^ R. Pöllänen, M.E. Ketterer, S. Lehto, M. Hokkanen, T.K. Ikäheimonen, T. Siiskonen, M. Moring, M.P. Rubio Montero and A. Martín Sánchez, "Multi-technique characterization of a nuclearbomb particle from the Palomares accident", Journal of Environmental Radioactivity, 2006, 90, 15-28
  10. ^ Rabideau, S.W., Journal of the American Chemical Society, 1957, 79, 6350-6353
  11. ^ P. G. Allen, J. J. Bucher, D. K. Shuh, N. M. Edelstein, and T. Reich, "Investigation of Aquo and Chloro Complexes of UO22+, NpO2+, Np4+, and Pu3+ by X-ray Absorption Fine Structure Spectroscopy ", Inorganic Chemistry, 1997, 36, 4676-4683
  12. ^ David L. Clark, Steven D. Conradson, D. Webster Keogh Phillip D. Palmer Brian L. Scott and C. Drew Tait, "Identification of the Limiting Species in the Plutonium(IV) Carbonate System. Solid State and Solution Molecular Structure of the [Pu(CO3)5]6- Ion", Inorganic Chemistry, 1998, 37, 2893-2899
  13. ^ Jörg Rothe, Clemens Walther, Melissa A. Denecke, and Th. Fanghänel, "XAFS and LIBD Investigation of the Formation and Structure of Colloidal Pu(IV) Hydrolysis Products ", Inorganic Chemistry, 2004, 43, 4708-4718
  14. ^ M. C. Duff, D. B. Hunter, I. R. Triay, P. M. Bertsch, D. T. Reed, S. R. Sutton, G. Shea-McCarthy, J. Kitten, P. Eng, S. J. Chipera, and D. T. Vaniman, "Mineral Associations and Average Oxidation States of Sorbed Pu on Tuff", Environ. Sci. Technol, 1999, 33, 2163-2169
  15. ^ R.D. Whicker and S.A. Ibrahim, "Vertical migration of 134Cs bearing soil particles in arid soils: implications for plutonium redistribution", Journal of Environmental Radioactivity, 2006, 88, 171-188.
  16. ^ Generic Procedures for Assessment and Response during a Radiological Emergency, International Atomic Energy Agency TECDOC Series number 1162, published in 2000 [1]
  17. ^ Yul Roh, Shi V. Liu, Guangshan Li, Heshu Huang, Tommy J. Phelps, and Jizhong Zhou, "Isolation and Characterization of Metal-Reducing Thermoanaerobacter Strains from Deep Subsurface Environments of the Piceance Basin, Colorado", Applied and Environmental Microbiology, 2002, 68, 6013-6020.
  18. ^ Joanna C. Renshaw, Laura J. C. Butchins, Francis R. Livens, Iain May, John M. Charnock, and Jonathan R. Lloyd, Environ. Sci. Technol., 2005, 39(15), 5657-5660.
Hentet fra "https://da.wikipedia.org/w/index.php?title=Bruger:Sasha/Kladde1&oldid=3662117"