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31.
Desirae L. Deskins Shidrokh Ardestani Pampee P. Young 《Journal of visualized experiments : JoVE》2012,(62)
Wound healing is a complicated, multistep process involving many cell types, growth factors and compounds1-3. Because of this complexity, wound healing studies are most comprehensive when carried out in vivo. There are many in vivo models available to study acute wound healing, including incisional, excisional, dead space, and burns. Dead space models are artificial, porous implants which are used to study tissue formation and the effects of substances on the wound. Some of the commonly used dead space models include polyvinyl alcohol (PVA) sponges, steel wire mesh cylinders, expanded polytetrafluoroethylene (ePTFE) material, and the Cellstick1,2.Each dead space model has its own limitations based on its material''s composition and implantation methods. The steel wire mesh cylinder model has a lag phase of infiltration after implantation and requires a long amount of time before granulation tissue formation begins1. Later stages of wound healing are best analyzed using the ePTFE model1,4. The Cellstick is a cellulose sponge inside a silicon tube model which is typically used for studying human surgery wounds and wound fluid2. The PVA sponge is limited to acute studies because with time it begins to provoke a foreign body response which causes a giant cell reaction in the animal5. Unlike other materials, PVA sponges are easy to insert and remove, made of inert and non-biodegradable materials and yet are soft enough to be sectioned for histological analysis2,5.In wound healing the PVA sponge is very useful for analyzing granulation tissue formation, collagen deposition, wound fluid composition, and the effects of substances on the healing process1,2,5. In addition to its use in studying a wide array of attributes of wound healing, the PVA sponge has also been used in many other types of studies. It has been utilized to investigate tumor angiogenesis, drug delivery and stem cell survival and engraftment1,2,6,7. With its great alterability, prior extensive use, and reproducible results, the PVA sponge is an ideal model for many studies1,2.Here, we will describe the preparation, implantation and retrieval of PVA sponge disks (Figure 1) in a mouse model of wound healing. 相似文献
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The interaction between the nucleic acid bases and solvent molecules has an important effect in various biochemical processes. We have calculated total energy and free energy of the solvation of DNA bases in water by Monte Carlo simulation. Adenine, guanine, cytosine, and thymine were first optimized in the gas phase and then placed in a cubic box of water. We have used the TIP3 model for water and OPLS for the nucleic acid bases. The canonical (T, V, N) ensemble at 25°C and Metropolis sampling technique have been used. Good agreement with other available computational data was obtained. Radial distribution functions of water around each site of adenine, guanine, cytosine, and thymine have been computed and the results have shown the ability of the sites for hydrogen bonding and other interactions. The computations have shown that guanine has the highest value of solvation free energy and N7 and N6 in adenine and guanine, N3 in cytosine, and N3 and O4 in thymine have the largest radial distribution function. Monte Carlo simulation has also been performed using the CHARMM program under the same conditions, and the results of two procedures are compared. 相似文献
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Allelic frequency and genotypes of prion protein at codon 136 and 171 in Iranian Ghezel sheep breeds
Siamak Salami Reza Ashrafi Zadeh Mir Davood Omrani Fatemeh Ramezani Amir Amniattalab 《朊病毒》2011,5(3):228-231
PrP genotypes at codons 136 and 171 in 120 Iranian Ghezel sheep breeds were studied using allele-specific PCR amplification and compared with the well-known sheep breeds in North America, the United States and Europe. The frequency of V allele and VV genotype at codon 136 of Ghezel sheep breed was significantly lower than AA and AV. At codon 171, the frequency of allele H was significantly lower than Q and R. Despite the similarities of PrP genotypes at codons 136 and 171 between Iranian Ghezel sheep breeds and some of the studied breeds, significant differences were found with others. Planning of effective breeding control and successful eradication of susceptible genotypes in Iranian Ghezel sheep breeds will not be possible unless the susceptibility of various genotypes in Ghezel sheep breeds to natural or experimental scrapie has been elucidated.Key words: scrapie, Ghezel sheep breed, PrP genotyping, allele specific amplification, codon 136, codon 171Scrapie was first described in England in 1732,1 and it is an infectious neurodegenerative fatal disease of sheep and goats belonging to the group of transmissible subacute spongiform encephalopathies (TSEs), along with bovine spongiform encephalopathy (BSE), chronic wasting disease and Creutzfeldt-Jakob disease.2,3 The term prion, proteinaceous infectious particles, coined by Stanley B. Prusiner, was introduced, and he presents the idea that the causal agent is a protein.4 Prion proteins are discovered in two forms, the wild-type form (PrPc) and the mutant form (PrPSc).5 Although scrapie is an infectious disease, the susceptibility of sheep is influenced by genotypes of the prion protein (PrP) gene.2,6 Researchers have found that the PrP allelic variant alanine/arginine/arginine (ARR) at codons 136, 154 and 171 is associated with resistance to scrapie in several breeds.7–14 Most of the sheep populations in the Near East and North African Region (84% of the total population of 255 million) are raised in Iran, Turkey, Pakistan, Sudan, Algeria, Morocco, Afghanistan, Syria and Somalia.15 In 2003, the Iranian sheep population was estimated at 54,000,000 head. The Ghezel sheep breed, which also is known as Kizil-Karaman, Mor-Karaman, Dugli, Erzurum, Chacra, Chagra, Chakra, Gesel, Gezel, Kazil, Khezel, Khizel, Kizil, Qezel, Qizil and Turkish Brown, originated in northwestern Iran and northeastern Turkey. By considering sheep breeds as one of the main sources of meat, dairy products and related products, a global screening attempt is started in different areas. In compliance with European Union Decision 2003/100/EC, each member state has introduced a breeding program to select for resistance to TSEs in sheep populations to increase the frequency of the ARR allele. A similar breeding program is established in United States and Canada. The Near East and North African Region still needs additional programs to help the global plan of eradication of scrapie-susceptible genotypes. The current study was the first to assess the geographical and molecular variation of codons 136 and 171 polymorphism between Iranian Ghezel sheep breed and well-known sheep breeds.Polymorphism at codon 136 is associated with susceptibility to scrapie in both experimental and natural models.10,11,13,16 17 and Austrian Carynthian sheep.18 Swiss White Alpine showed higher frequency of allele V at position 136 than Swiss Oxford Down, Swiss Black-Brown Mountain and Valais Blacknose.19 Comparison of polymorphism at codon 136 in the current study with some of other breeds (20 some flock of Hampshire sheep21 with current study, but the frequency of it is higher than that of some other breeds.
Open in a separate windowIt has been found that a polymorphism at codon 171 also is associated with susceptibility to experimental scrapie in Cheviot sheep16 and natural scrapie in Suffolk sheep.22 As shown in 23 They also found that different breeds show different predominant genotypes in ewes and rams.23 Different PrP genotypes were found at codon 171 in Austrian sheep breeds, but QQ has higher frequency than others.18 In some kinds of Swiss breeds, allelic frequencies of allele Q was higher than R.19 Distribution of prion protein codon 171 genotypes in Hampshire sheep revealed that different flocks shows different patterns.21 The frequency of PrP genotypes at codon 171 in Iranian Ghezel breeds was similar to some sheep breeds, like the Suffolk breed of Oklahoma sheep, but it was completely different from others (PrP genotypes at codon 172 Breed Allelic frequency Genotypes Reference Q R H RR QR QQ QH RH HH Iranian Iranian Ghezel breeds (n = 120) 55.00 43.33 1.67 23.33 36.67 36.67 0.00 3.33 0.00 Current study Oklahoma sheep (n = 334) De Silva, et al.20 Suffolk 40.95 59.05 0.00 37.07 43.97 18.97 0.00 0.00 0.00 Hampshire 51.89 48.11 0.00 21.70 52.83 25.47 0.00 0.00 0.00 Dorset 67.75 31.25 0.00 7.95 46.59 45.45 0.00 0.00 0.00 Montadale 62.96 37.04 0.00 14.81 44.44 40.74 0.00 0.00 0.00 Hampshire (n = 201) 72.14 26.60 1.26 5.00 42.00 50.00 2.00 1.00 0.00 Youngs, et al.21 German Sheep Breeds (n = 660) Kutzer, et al.28 Bleu du Maine 37.8 62.2 0.00 46.96 30.44 22.6 0.00 0.00 0.00 Friesian Milk S. 90.45 8.9 0.65 1.27 15.3 82.8 0.00 0.00 0.64 Nolana 42.3 57.8 0.00 36.62 42.26 21.13 0.00 0.00 0.00 Suffolk 68.4 27.6 4.0 16.1 21.84 55.17 4.6 1.15 1.15 Texel 55.35 29.7 14.9 12.56 26.83 36.36 11.25 7.36 5.63 Swiss Sheep (n = 200) Gmur, et al.19 Swiss Oxford Down 32.00 68.00 - - - - - - - Swiss Black-Brown M. 70.00 30.00 - - - - - - - Valais Blacknose 85.00 15.00 - - - - - - - Swiss White Alpine 27.00 73.00 - - - - - - - Austrian Sheep (n = 112) Sipos, et al.18 Tyrolean mountain sheep 74.30 25.80 0.00 2.90 45.70 51.40 0.00 0.00 0.00 Forest sheep 77.00 19.20 3.80 11.50 15.40 69.20 0.00 0.00 3.80 Tyrolean stone sheep 81.50 14.80 3.70 0.00 29.60 62.90 7.40 0.00 0.00 Carynthian sheep 72.80 23.00 4.20 4.20 41.70 13.00 8.40 0.00 0.00
Table 1
Comparison of PrP allelic and genotype frequencies at codon 136 in different breedsBreed | A (%) | V (%) | AA (%) | AV (%) | VV (%) | Reference |
Iranian Ghezel breeds (n = 120) | 77.50 | 22.5 | 65.00 | 25.00 | 10.00 | Current study |
Oklahoma sheep (n = 334) | De Silva, et al.27 | |||||
Suffolk | 99.24 | 0.76 | 98.48 | 1.52 | 0.00 | |
Hampshire | 100 | 0.00 | 100 | 0.00 | 0.00 | |
Dorset | 92.6 | 7.94 | 87.30 | 9.52 | 3.17 | |
Montadale | 77.66 | 22.34 | 59.57 | 36.17 | 4.26 | |
Hampshire (n = 48) | 93.75 | 6.25 | 88.00 | 12.00 | 0.00 | Youngs, et al.21 |
German Sheep Breeds (n = 660) | 92.89 | 7.11 | 87.80 | 10.47 | 1.73 | Kutzer, et al.28 |
Bleu du Maine | 83.47 | 16.53 | 69.56 | 27.83 | 2.61 | |
Friesian Milk S. | 100 | 0.00 | 100 | 0.00 | 0.00 | |
Nolana | 90.13 | 9.87 | 85.90 | 8.46 | 5.64 | |
Suffolk | 100 | 0.00 | 100 | 0.00 | 0.00 | |
Texel | 90.87 | 9.13 | 82.16 | 17.41 | 0.43 | |
Swiss Sheep (n = 200) | 92.5 | 7.5 | Gmur, et al.19 | |||
Swiss Oxford Down | 93.00 | 7.00 | - | - | - | |
Swiss Black-Brown M. | 99.00 | 1.00 | - | - | - | |
Valais Blacknose | 100 | 0.00 | - | - | - | |
Swiss White Alpine | 88.00 | 22.00 | - | - | - | |
Austrian Sheep (n = 112) | 98.95 | 1.05 | 98.95 | 0.00 | 1.05 | Sipos, et al.18 |
Tyrolean mountain sheep | 100 | 0.00 | 100 | 0.00 | 0.00 | |
Forest sheep | 100 | 0.00 | 100 | 0.00 | 0.00 | |
Tyrolean stone sheep | 100 | 0.00 | 100 | 0.00 | 0.00 | |
Carynthian sheep | 95.80 | 4.20 | 95.80 | 0.00 | 4.20 |