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Radionuclide Generators
Published in Garimella V. S. Rayudu, Lelio G. Colombetti, Radiotracers for Medical Applications, 2019
Chromatography, the method of choice in most cases, was first used in the separation of 99mTc from 99Mo by Richards and co-workers in 1957.37 The column utilized by Richards was essentially the same as those originally described in chromatographic separations. The original columns were open, as shown in Figure 5 and the product obtained was not sterile; therefore, sterilization, usually effected by micropore filtration, was mandatory. The columns used today are essentially the same, despite the many changes that have been made in the design of the generator system, including the development of closed systems,15, 16, 24 intended to assure that the eluates are sterile, pyrogen-free solutions suitable for i.v. administration.38Figure 6 shows the milking station of a modern chromatographic generator system. Many generators of this type have been developed for commercial use. The modern radionuclide generator consists of a small glass or plastic cylinder fitted at the bottom with a fritted glass disc of medium porosity, containing a column of an ion exchange resin,13, 16, 39 or an inorganic ion exchanger such as alumina,4 silicic acid,40 manganese dioxide,41 hydrous zirconium oxide,14 etc. Inorganic exchange media are preferable since prolonged radiation is more likely to decompose organic resins. Furthermore, inorganic resins are easier to keep free from biological contamination.
III-Nitrides–Based Biosensing
Published in Iniewski Krzysztof, Integrated Microsystems, 2017
Manijeh Razeghi, Ryan McClintock
The system operates by using a small vacuum pump to draw in a sample of air with potential biological contamination. A miniature virtual impact-based aerosol concentrator is used to enhance the concentration of any particulate matter in the incoming air. This concentrated air is then drawn through the center of the integrating sphere. A laminar flow of filtered shield gas surrounds this central column of sample gas to avoid contamination of the interior of the integrating sphere. The various III-nitride sources are placed in a ring coaxial with the sample gas flow. Stray light from the LEDs is captured by an outlet baffle integrated into the gas outlet at the bottom of the sphere. The LEDs are sequentially illuminated for a brief pulse with the corresponding detector’s output sampled for any detection events. This sequence repeats until all LED–detector combinations have been tested. The LEDs and detectors are controlled by a CPU/driver board that creates a florescence fingerprint for each sample. These fingerprints are compared against the time-varying background and against a database of calibrated fingerprints to make a determination as to the biological contents of the sampled air. This output can be used to make a qualitative analysis of a sample of unknown gas and can be directly wired to alarm circuits that provide advance warning if any unusual detection event occurs.
Dental Implant Infection: Typical Causes and Control
Published in Huiliang Cao, Silver Nanoparticles for Antibacterial Devices, 2017
The removal of bacteria biofilm should be performed as an initial preparative measure for peri-implant infection treatments. The treatment of peri-implant infections comprises conservative (nonsurgical) and surgical approaches. Depending on the severity of the peri-implant disease (mucositis, moderate or severe peri-implantitis), a nonsurgical therapy alone might be sufficient or a stepwise approach with a nonsurgical therapy followed by a surgical treatment may be necessary. In fact, the removal of biological contamination from common implant surfaces is difficult to achieve, however, because of various surface modifications. In this context, apart from the mechanical removal of the biofilm, decontamination or conditioning of the exposed implant surface is also encouraged in order to optimise the removal of bacterial contaminants from the microstructured implant surface. The indication for the appropriate treatment strategy has been developed and documented as the ‘cumulative interceptive supportive therapy (CIST)’ concept (Lang et al. 2004; Mombelli 1997; Mombelli and Lang 1998). In the consensus conference of the International Team for Implantology, as the milestone meeting of modern dental implantology, the CIST was modified and called AKUT concept (Table 14.1) (Lang et al. 2004). The basis of this concept is a regular recall of the implanted patients and repeated assessment of plaque, bleeding, suppuration, pockets and radiological evidence of bone loss.
Interaction between microorganisms and dental material surfaces: general concepts and research progress
Published in Journal of Oral Microbiology, 2023
Yan Tu, Huaying Ren, Yiwen He, Jiaqi Ying, Yadong Chen
In the oral cavity, the biofilm containing the host and bacterial proteins apparently influences bacterial adhesion. Biofilm formation is a complex process, and factors such as dietary intake and oral microbial composition significantly affect it. Studying the association between the surface performance of materials and bacterial adhesion has shown that negatively charged, superhydrophobic, superhydrophilic, and nano surfaces can all reduce bacterial adhesion. In addition, some positively charged surfaces can achieve antibacterial performance through coating with antibacterial materials. The research and developments concerning new dental materials are more reliable in the simulated oral environment. Therefore, we should combine different models to simulate the complex oral environment to develop and evaluate novel dental materials. This research field has laid a solid foundation for a profound awareness of bacterial systemic sensing surfaces and is very critical for the research and development of intelligent biomimetic dental materials to reduce biological contamination.
Prodigiosin as an antibiofilm agent against multidrug-resistant Staphylococcus aureus
Published in Biofouling, 2023
Jing Yan, Qi Yin, Hao Nie, Jinyou Liang, Xiang-Ru Liu, Yingli Li, Hong Xiao
Healthcare-associated infections (HAI) pervade hospital settings and healthcare personnel, attributable to the intricacy of the healthcare system, rampant antimicrobial usage, and the rise of multi-drug resistant (MDR) microorganisms, notably methicillin-resistant Staphylococcus aureus (MRSA) (Fernando et al. 2017; Monegro et al. 2022). This pathogen colonizes the skin, mucous membranes, and medical implants persistently, presenting a considerable hurdle to healthcare and public health. Manifestations range from mild skin infections to severe conditions like endocarditis, pneumonia, and sepsis (Liu and Dickter 2020). Several studies have revealed that hospitals are a significant factor in the emergence and spread of multi-drug resistant S. aureus to the surrounding aquatic environment (Mandal et al. 2015; Akya et al. 2020). Residual antibiotics from hospital wastewater treatment plants increase selection pressure in the aquatic environment, and microorganisms acquire and spread antibiotic-resistance genes via various transfer mechanisms. This antimicrobial-resistant (AMR) bacteria spread in hospital wastewater and municipal wastewater, urban water supplies, and agricultural and aquaculture systems, causing widespread infections and biological contamination of the environment (Kozajda et al. 2019; Girijan and Pillai 2021).
Rate limiting factors for DNA transduction induced by weak electromagnetic field
Published in Electromagnetic Biology and Medicine, 2019
B. Qing Tang, Tongju Li, Xuemei Bai, Minyi Zhao, Bing Wang, Glen Rein, Yongdong Yang, Peng Gao, Xiaohuan Zhang, Yanpeng Zhao, Qian Feng, Zhongzhen Cai, Yu Chen
One type of DNA cross contamination could be caused by the equipment, the shared space, the experimenters, as well as from the air circulation. This type of contamination is referred to as “biological contamination” in this paper. To avoid biological DNA cross contamination, we separated the whole procedure into different modules, and each module was carried out by an independent experimenter in a lab located in a different building. For the transduction step, the DNA solution was capped, rinsed thoroughly and then wrapped with layers of Parafilm before putting into the coil next to the aqueous solution. In addition, the aqueous solution was also capped and wrapped with layers of Parafilm. At the end of the transduction, the aqueous solution was taken out of the coil and rinsed thoroughly before removing the Parafilm. Finally, the vial was thoroughly rinsed again to completely remove any potential trace of DNA stuck to the outside of the vessel, although the likelihood of this happening is very slim given the extremely strict experimental protocol used. In this setup, the biological contamination of DNA is nearly impossible to occur.