The Xpert MTB/RIF is a cartridge based nucleic acid amplification test, automated diagnostic test that can identify Mycobacterium tuberculosis (MTB) DNA and resistance to rifampicin (RIF) by nucleic acid amplification test (NAAT). It was co-developed by the laboratory of Professor David Alland at the University of Medicine and Dentistry of New Jersey (UMDNJ). Cepheid Inc. and Foundation for Innovative New Diagnostics, with additional financial support from the US National Institutes of Health (NIH). In December 2010, the World Health Organization (WHO) endorsed the Xpert MTB/RIF for use in TB endemic countries. This followed 18 months of assessment of its field effectiveness in TB, MDR-TB and TB/HIV co-infection. This test, and others that are likely to follow, could have the potential to improve the diagnosis of TB in those that are likely to be missed by traditional tests. Tuberculosis is one of the ...
... (NEAR) is a method for in vitro DNA amplification like the polymerase chain reaction (PCR). NEAR is isothermal, replicating DNA at a constant temperature using a polymerase (and nicking enzyme) to exponentially amplify the DNA at a temperature range of 55 °C to 59 °C. One disadvantage of PCR is that it consumes time uncoiling the double-stranded DNA with heat into single strands (a process called denaturation) . This leads to amplification times typically thirty minutes or more for significant production of amplified products.[better source needed] Potential advantages of NEAR over PCR are increased speed and lower energy requirements, characteristics that are shared with other isothermal amplification schemes. A major disadvantage of NEAR relative to PCR is that production of nonspecific amplification products is a common issue with isothermal amplification reactions. The NEAR reaction uses naturally occurring or ...
A nucleic acid test (NAT) or nucleic acid amplification test (NAAT) is a molecular technique used to detect a particular pathogen (virus or bacterium) in a specimen of blood or other tissue or body fluid. It does so by detecting and amplifying the RNA or DNA of the pathogen, that is, making extra copies of its nucleic acids. This type of medical test was developed to shorten the window period, a time between when a patient has been infected and when they show up as positive by antibody tests such as ELISA. Whereas antibody positivity cannot occur until the immune system has had days or weeks to develop a sizable subpopulation of antibodies specific to the pathogen, a NAT can detect a pathogen as soon as it is present. The term includes any test that directly detects the genetic material of the infecting organism or virus, such as polymerase chain reaction, ligase chain reaction, and others. ...
... (PEAR) is a DNA amplification technology for the amplification of oligonucleotides. A target oligonucleotide and a tandem repeated antisense probe are subjected to repeated cycles of denaturing, annealing, elongation and cleaving, in which thermostable DNA polymerase elongation and strand slipping generate duplex tandem repeats, and thermostable endonuclease (PspGI) cleavage releases monomeric duplex oligonucleotides. PEAR has the potential to be a useful tool for: Large-scale production of oligonucleotides. PEAR is a minimal DNA replication system, so it can be considered as a minimal life system. it is of therectical interests to study the origin and evolution of repetitive DNA. The repetitive DNA products can be transferred directly into cells or organisms to study the function of the repetitive DNA. Wang, Xiaolong; Deming Gou; Shuang-yong Xu (January 1, 2010). "Polymerase-Endonuclease Amplification Reaction (PEAR) for Large-Scale Enzymatic ...
... (RPA) is a single tube, isothermal alternative to the polymerase chain reaction (PCR). By adding a reverse transcriptase enzyme to an RPA reaction it can detect RNA as well as DNA, without the need for a separate step to produce cDNA,. Because it is isothermal, RPA can use much simpler equipment than PCR, which requires a thermal cycler. Operating best at temperatures of 37-42 °C and still working, albeit more slowly, at room temperature means RPA reactions can in theory be run quickly simply by holding a tube. This makes RPA an excellent candidate for developing low-cost, rapid, point-of-care molecular tests. A recent international quality assessment of molecular detection of Rift Valley fever virus performed as well as the best RT-PCR tests, detecting less concentrated samples missed by some PCR tests and an RT_LAMP test. RPA was developed and launched by TwistDx Ltd. (formerly known as ASM Scientific Ltd), a biotechnology company based in Cambridge, UK. ...
... are antibodies targeting bacteria of the Chlamydia genus, but it generally refers specifically to antibodies targeting Chlamydia trachomatis, which is the cause of Chlamydia infection in humans. Testing for Chlamydia antibodies is not the mainstay diagnostic tool for Chlamydia infection, which is preferentially diagnosed by Nucleic acid amplification tests (NAAT) such as polymerase chain reaction (PCR). However, testing for Chlamydia antibodies is a cost-effective screening device in detecting fallopian tube pathology, as it is often related to Chlamydia infection. The preferred technique for this purpose is by micro-immunofluorescence (MIF), because it is superior in the assessment of tubal pathology when compared with immunofluorescence (IF) or enzyme-linked immunosorbent assay (ELISA). Kodaman PH, Arici A, Seli E (June 2004). "Evidence-based diagnosis and management of tubal factor infertility". Current Opinion in Obstetrics and Gynecology. 16 (3): ...
In biology, a branched DNA assay is a signal amplification assay (as opposed to a target amplification assay) that is used to detect nucleic acid molecules. A branched DNA assay begins with a dish or some other solid support (e.g., a plastic dipstick). The dish is peppered with small, single stranded DNA molecules (or chains) that 'stick up' into the air. These are known as capture probe DNA molecules. Next, an extender DNA molecule is added. Each extender has two domains; one that hybridizes to the capture DNA molecule and one that "hangs out" in the air. The purpose of the extender is two-fold. First, it creates more available surface area for target DNA molecules to bind, and second, it allows the assay to be easily adapted to detect a variety of target DNA molecules. Once the capture and extender molecules are in place and they have hybridized, the sample can be added. Target molecules in the sample will bind to the extender molecule. ...
A concept similar to that of PCR had been described before Mullis' work. Nobel laureate H. Gobind Khorana and Kjell Kleppe, a Norwegian scientist, authored a paper 17 years earlier describing a process they termed "repair replication" in the Journal of Molecular Biology.[26] Using repair replication, Kleppe duplicated and then quadrupled a small synthetic molecule with the help of two primers and DNA polymerase. The method developed by Mullis, used repeated thermal cycling, which allowed the rapid and exponential amplification of large quantities of any desired DNA sequence from an extremely complex template. Later a heat-stable DNA polymerase was incorporated into the process. His co-workers at Cetus, who were embittered by his abrupt departure from the company,[10] contested that Mullis was solely responsible for the idea of using Taq polymerase in PCR. However, other scientists have written that the "full potential [of PCR] was not realized" until Mullis' work in 1983,[27] and that ...
... (CPT) is a molecular biological technique for detecting specific DNA sequences. CPT operates under isothermal conditions. In some applications, CPT offers an alternative to PCR. However, unlike PCR, CPT does not generate multiple copies of the target DNA itself, and the amplification of the signal is linear, in contrast to the geometric amplification of the target DNA in PCR. CPT uses a sequence specific chimeric probe which hybridizes to a complementary target DNA sequence and becomes a substrate for RNase H. Cleavage occurs at the RNA internucleotide linkages and results in dissociation of the probe from the target, thereby making it available for the next probe molecule. Integrated electrokinetic systems have been developed for use in CPT. Bhatt, R; Scott, B; Whitney, S; Bryan, R; et al. (1999). "Detection of nucleic acids by cycling probe technology on magnetic particles: high sensitivity and ease of separation". Nucleosides ...
With air-displacement plethysmography, the volume of an object is measured indirectly by determining the volume of air it displaces inside an enclosed chamber (plethysmograph). Thus, human body volume is measured when a subject sits inside the chamber and displaces a volume of air equal to his or her body volume. Body volume is calculated indirectly by subtracting the volume of air remaining inside the chamber when the subject is inside from the volume of air in the chamber when it is empty. The volume of air inside the chamber is calculated by slightly changing the size of the chamber (e.g. by moving a diaphragm in one of the walls) and applying relevant physical gas laws to determine the total volume from the changing air pressure within the chamber as its size is altered. Boyle's law states that at a constant temperature, volume (V) and pressure (P) are inversely related. Therefore, when a constant temperature is maintained (isothermal conditions), Boyle's law can be applied. Consequently, ...
Traditionally, gonorrhea was diagnosed with Gram stain and culture; however, newer polymerase chain reaction (PCR)-based testing methods are becoming more common.[16][28] In those failing initial treatment, culture should be done to determine sensitivity to antibiotics.[29] Tests that use polymerase chain reaction (PCR, aka nucleic acid amplification) to identify genes unique to N. gonorrhoeae are recommended for screening and diagnosis of gonorrhea infection. These PCR-based tests require a sample of urine, urethral swabs, or cervical/vaginal swabs. Culture (growing colonies of bacteria in order to isolate and identify them) and Gram-stain (staining of bacterial cell walls to reveal morphology) can also be used to detect the presence of N. gonorrhoeae in all specimen types except urine.[30][31] If Gram-negative, oxidase-positive diplococci are visualized on direct Gram stain of urethral pus (male genital infection), no further testing is needed to establish ...
The ligase chain reaction (LCR) is a method of DNA amplification. While the better-known PCR carries out the amplification by polymerizing nucleotides, LCR instead amplifies the nucleic acid used as the probe. For each of the two DNA strands, two partial probes are ligated to form the actual one; thus, LCR uses two enzymes: a DNA polymerase (used for initial template amplification and then inactivated) and a thermostable DNA ligase. Each cycle results in a doubling of the target nucleic acid molecule. A key advantage of LCR is greater specificity as compared to PCR. It has been widely used for the detection of single base mutations, as in genetic diseases. LCR and PCR may be used to detect gonorrhea and chlamydia, and may be performed on first-catch urine samples, providing easy collection and a large yield of organisms. Endogenous inhibitors limit the sensitivity, but if this effect could ...
... was one of the first biotechnology companies. It was established in Berkeley, California in 1971, but conducted most of its operations in nearby Emeryville. Before merging with another company in 1991, it developed several significant pharmaceutical drugs as well as a revolutionary DNA amplification technique. Cetus was founded in 1971 by Ronald E. Cape, Peter Farley, and Nobelist Donald A. Glaser. Its early efforts involved automated methods to select for industrial microorganisms that could produce greater amounts of chemical feedstocks, antibiotics, or vaccine components. By the late-1970s, however, three new revolutionary techniques had been developed: recombinant DNA, monoclonal antibodies, and gene expression, the foundations of the biotechnology industry. In order to enter these new fields, Cetus raised $108 million in an Initial Public Offering in 1981, the largest IPO to that date. Its first large development project, in conjunction with Triton Biosciences, was ...