Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 37

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  metoda Real Time PCR
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Polymerase chain reaction (PCR) has for many years been regarded as the new standard procedure in detecting the genes of microorganisms, plants and animals. Detecting the reacting products is reliant upon agarose gel electrophoresis, ethidium bromide staining, ultraviolet irradiation and comparing the size to a DNA size marker. This has slowed progress in adopting the PCR method in diagnostic laboratories. Developing new methods of PCR product detection without opening a reaction tube has opened new possibilities in applying this technique during routine diagnosis. Monitoring PCR product accumulation as amplification progresses is possible through using labeled primers and/or oligonucleotide probes or DNA binding fluorophores. Real-Time PCR methods can be subdivided into two groups: sequence dependent or sequence independent DNA detection. All of these involve using fluorophores linked to oligonucleotides or their presence in the reaction mixture. Their common feature is measuring fluorescence in each PCR cycle and calculating the threshold cycle that corresponds to the DNA copy number in that sample.
Pestiviruses cause serious diseases in domestic and wild ruminants and swine. The aim of the study was to apply Real Time PCR with SYBR Green I intercalating dye for detecting pestiviruses. The study was performed with RNA extracted from BVDV-1 cell culture and CSFV, DNA templates with known copy numbers synthesized from CSFV, BVDV-1 and BDV and on cDNA samples representing different pestivirus species and strains. Two PCR kits were used in the study: AmpliTaq Gold (Applied Biosystems) with added fluorescent dyes, and QuantiTect SYBR Green PCR kits (Qiagen). PCR primers were selected from 5UTR. All pestivirus species, or species-related samples were detected using the applied method and the results were observed as amplification curves. The specificity of amplification was confirmed by estimating the melting temperature of the PCR products. It was demonstrated that the melting temperature of amplicons obtained in reaction with QuantiTect kit was 86-87°C while those obtained with AmpliTaq Gold was 90-92°C. A higher assay sensitivity of 40 copies of CSFV, 400 copies of BVDV and 40 000 copies of BDV templates was obtained using the QuantiTect SYBR Green PCR kit. It should be stressed that the above method does not facilitate pestivirus species identification and may only be a preliminary method for detecting pestivirus infections in swine and must be supplemented with CSFV specific assay.
In recent years a considerable improvement has been reported in the field of molecular biology. New molecular methods have replaced classic diagnostic techniques. Apart from pathogen detection, they also allow pathogen quantification in a relatively short time. For instance, real time PCR, thanks to using DNA-binding fluorophores or labelled oligonucleotide probes, allows the detection of virus and monitoring of each cycle of reaction. The use of complementary probes makes this method sensitive and specific. Real time PCR is widely applied, especially in microbiological and virological laboratories, also for rabies diagnostics. Additionally, it is an excellent tool in biomedical and molecular research. For example, it is used for relative and absolute quantification of gene expression and the identification of mutations that might be a key issue in some diseases. Recently, real time PCR seems to become a standard technique in many diagnostic laboratories.
Equine herpesvirus type 1 (EHV-1) is one of the major horse diseases, causing considerable worldwide losses. A variety of techniques, including nested PCR, have been used to diagnose EHV-1 infections. In this paper, a real-time PCR assay that uses non-specific SYBR Green I® fluorochrome for the detection of EHV-1 DNA is described. This method does not require post-amplification manipulations, thereby reducing the risk of cross-contamination. The assay was sensitive enough to detect EHV-1 sequences in neuronal cell cultures and also different clinical samples. The technique is specific: it was not reactive with other herpesviruses or opportunistic bacterial pathogens such as Escherichia coli, Staphylococcus epidermidis and Enterococcus faecium. In comparison to virus isolation or the nested PCR used previously, the test was more sensitive and should be useful for the common diagnosis based on its specificity and rapidity.
The aim of the study was to apply the real-time PCR method with the intercalating dye SYBR Green I for the detection of genes of Bacillus anthracis located on plasmids pXO1 and pXO2 and the specific chromosomal rpoB sequence. The research was conducted on one vaccinal and four field strains of Bacillus anthracis. The assessment of the specificity of the tests involved isolates of other species of the genus Bacillus as well as strains of six other species of microorganisms. The studies were conducted with the PCR QuantiTect kit (Qiagen) and primers specific for the gene pag coding PA protein, gene cap coding capsule, and primers for the amplification of the specific chromosomal sequence. PCR enabled the detection of all genes under examination by the observation of amplification curves. The specificity of real-time PCR was confirmed by estimating melting temperatures of PCR products. It was shown that the melting temperatures of amplicons obtained in the reaction were 78°C, 79°C and 76°C in cases of detecting the chromosomal rpoB sequence, pag gene, and cap-C gene, respectively. The sensitivity and linearity of the reactions were determined using a regression coefficient. A high regression coefficient of 0.99 was demonstrated for all the reactions. The real-time tests were highly sensitive and specific.
The diagnostics of brucellosis is primarily based on serological investigations. Since a serologically positive response can occur from antigenically cross-reactive bacteria, the isolation and identification of the pathogen from a potentially infected host remains the gold standard as a tool for the confirmation of infection. However, this process also has drawbacks. The tests are time consuming, complex and must be performed by highly skilled personnel. The zoonotic nature of most Brucella species is a potential hazard for laboratory personnel who must manipulate the infectious agent during testing. Finally, some of the characteristics are subjective and the results are not always definitive. Recently, progress in these aspects of diagnostics has been advanced through PCR-based technologies. PCR-based assays are simple to design and carry out, rapid, inexpensive to perform and are characterized by high diagnostic values: sensitivity and specificity. The following is a review of the major assays constituting excellent progress in the diagnostics of brucellosis.
Under current regulations, it is possible to export processed animal proteins originating from tissues of animals other than ruminants. In order to ensure appropriate control, studies were undertaken to adopt a real-time PCR method for the analysis of processed products of animal origin. The material consisted of raw by-products of beef, pork and poultry. In the assays, mitochondrial DNA was used. The modified method is capable of detecting ruminant DNA at a level of 0.025%. The results of validation studies demonstrate that the real-time PCR method can be used in routine tests to identify ruminant DNA in raw animal by-products.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.