BACKGROUND: DNA damage occurs as a consequence of both direct and indirect effects of ionizing radiation. The severity of DNA damage depends on the physical characteristics of the radiation quality, e.g., the linear energy transfer (LET). There are still contrary findings regarding direct or indirect interactions of high-LET emitters with DNA. Our aim is to determine DNA damage and the effect on cellular survival induced by (223)Ra compared to (188)Re and (99m)Tc modulated by the radical scavenger dimethyl sulfoxide (DMSO). METHODS: Radioactive solutions of (223)Ra, (188)Re, or (99m)Tc were added to either plasmid DNA or to PC Cl3 cells in the absence or presence of DMSO. Following irradiation, single strand breaks (SSB) and double strand breaks (DSB) in plasmid DNA were analyzed by gel electrophoresis. To determine the radiosensitivity of the rat thyroid cell line (PC Cl3), survival curves were performed using the colony formation assay. RESULTS: Exposure to 120 Gy of (223)Ra, (188)Re, or (99m)Tc leads to maximal yields of SSB (80 %) in plasmid DNA. Irradiation with 540 Gy (223)Ra and 500 Gy (188)Re or (99m)Tc induced 40, 28, and 64 % linear plasmid conformations, respectively. DMSO prevented the SSB and DSB in a similar way for all radionuclides. However, with the α-emitter (223)Ra, a low level of DSB could not be prevented by DMSO. Irradiation of PC Cl3 cells with (223)Ra, (188)Re, and (99m)Tc pre-incubated with DMSO revealed enhanced survival fractions (SF) in comparison to treatment without DMSO. Protection factors (PF) were calculated using the fitted survival curves. These factors are 1.23 ± 0.04, 1.20 ± 0.19, and 1.34 ± 0.05 for (223)Ra, (188)Re, and (99m)Tc, respectively. CONCLUSIONS: For (223)Ra, as well as for (188)Re and (99m)Tc, dose-dependent radiation effects were found applicable for plasmid DNA and PC Cl3 cells. The radioprotection by DMSO was in the same range for high- and low-LET emitter. Overall, the results indicate the contribution of mainly indirect radiation effects for each of the radionuclides regarding DNA damage and cell survival. In summary, our findings may contribute to fundamental knowledge about the α-particle induced DNA damage.

Haemophilus influenzae is a host adapted human mucosal pathogen involved in a variety of acute and chronic respiratory tract infections, including chronic obstructive pulmonary disease and asthma, all of which rely on its ability to efficiently establish continuing interactions with the host. Here we report the characterization of a novel molybdenum enzyme, TorZ/MtsZ that supports interactions of H. influenzae with host cells during growth in oxygen-limited environments. Strains lacking TorZ/MtsZ showed a reduced ability to survive in contact with epithelial cells as shown by immunofluorescence microscopy and adherence/invasion assays. This included a reduction in the ability of the strain to invade human epithelial cells, a trait that could be linked to the persistence of H. influenzae. The observation that in a murine model of H. influenzae infection, strains lacking TorZ/MtsZ were almost undetectable after 72 h of infection, while similar to 3.6 x 10(3) CFU/mL of the wild type strain were measured under the same conditions is consistent with this view. To understand how TorZ/MtsZ mediates this effect we purified and characterized the enzyme, and were able to show that it is an S- and N-oxide reductase with a stereospecificity for S-sulfoxides. The enzyme converts two physiologically relevant sulfoxides, biotin sulfoxide and methionine sulfoxide (MetSO), with the kinetic parameters suggesting that MetSO is the natural substrate of this enzyme. TorZ/MtsZ was unable to repair sulfoxides in oxidized Calmodulin, suggesting that a role in cell metabolism/energy generation and not protein repair is the key function of this enzyme. Phylogenetic analyses showed that H. influenzae TorZ/MtsZ is only distantly related to the Escherichia colt TorZ TMAO reductase, but instead is a representative of a new, previously uncharacterized Glade of molybdenum enzyme that is widely distributed within the Pasteurellaceae family of pathogenic bacteria. It is likely that MtsZ/TorZ has a similar role in supporting host/pathogen interactions in other members of the Pasteurellaceae, which includes both human and animal pathogens.

Regenerative medicine is an emerging technology and with hundreds of cell therapies currently in clinical trials there is a need to expand the limited knowledge related to their storage, shipment and preservation. The most widely used medium for human cell cryopreservation is 10%wt dimethyl sulfoxide (DMSO) in serum. However given its potential toxicity, DMSO usage is a key issue in cryopreservation. Methods specify the need to reduce cell exposure time to DMSO above 0°C as much as possible but the maximum amount of time cells can be exposed to DMSO to prevent a detrimental effect needs to be clarified. There are also regulatory issues and concerns with the xenotoxicity, ethics and supply of the other core component in the standard cryomedia formulation: Foetal Bovine Serum (FBS). Developing a viable alternative to FBS is crucial. In cryobiology literature thawing appears poorly understood. A stable process is as vital as freezing to prevent injury to cells. Protocols are currently too vague for cell therapy regulation and need improvement. The time dependent DMSO cytotoxicity was evaluated by overexposing cells to DMSO during and/or after cryopreservation. A broad investigation found that after 1 hour overexposure post thaw viability of human mesenchymal stem cells (hMSCs) was reduced from 96.3±0.6% to 74.1±4.0% and the co-expression of five key hMSC markers was changed from 97.9±1.3% to 68.3±2.6%. This significant change could cause indicate a change in product efficacy and affect patient health, to prevent this, DMSO exposure must be kept to below 1 hour. A range of alternative vehicle solutions were screened and human platelet lysate (hPL) investigated as an alternative. In depth experimentation with hPL as a cryopreservation vehicle solution and culture supplement (in place of FBS) found it to be a worthy, statistically similar alternative. With no xenological or ethical concerns, lower costs than other serum-free alternatives hPL could allow for a move away from xenological components. A heat transfer model was developed and determined that 720J is required to thaw a vial. Using the heat transfer model and additional factors such as pre-thaw stabilisation and on thaw dilution, a two-stage experiment found that the current standard process (warming in a 37°C waterbath) within the current paradigm of a 1.8mL cryovial is optimal but further work is required to define the process for scaled-up product.

<p>The study introduces and puts forward Sector Policing as a model to expand community Policing and to broaden the scope of crime prevention. It also demonstrates how Sector Policing can be utilised to decentralise policing and deepen community participation.</p>

Abstract DMSO (dimethyl sulfoxide) has merits of a high boiling point and high solution power to most photo-resistant materials used in semiconductor and LCD (liquid crystal displayers) industries. Wastewaters originated from the industries contain hundreds of grams of DMSO per cubic mater. DMSO is easily decomposed to DMS (dimethyl sulfide) and DMSO2 (dimethyl sulfone) by microorganisms in biological reactors. Malodorous DMS has a relatively low water solubility and can easily emit into the atmosphere thus causes nuisance problems. The fraction of conversion of DMSO to DMS is possibly related to the volumetric DMSO loading (F/V) to an aerobic wastewater treatment pond. This study aimed to investigate the volumetric DMSO loading which minimize the DMS production. Sequencing batch reaction tests indicate that with F/V of less than 0.45 kg DMSO-S/m3.day, there was no DMS detected in the treating mixed liquor and the vented gas from the liquor. It was also observed that with sulfate-S of higher than 0.55 kg/m3 in the mixed liquor which corresponded to F/V of 0.55 kg DMSO-S/m3.day, a high conversion of DMSO to DMS resulted in the system failure.

Coating of fine pthesiss to produce tailored surface properties is currently a key development for supercritical fluids applications, in different areas such as: pharmaceutical, nutraceutical, cosmetic, agrochemical, electronic and specialty chemistry industries. During the encapsulation process the pthesis surface can be designed with specific properties by spreading a thin film coating material over the surface of the pthesiss. Chitosan, a natural polymer, was used in this work as the encapsulant material. Chitosan is biocompatible, biodegradable to normal body constituents, safe, non-toxic, bacteriostatic, anticancerogen, and versatile polymer. These attributes are among the properties that make Chitosan an attractive component of pharmaceutical products. The main objective of this research was to encapsulate solid pthesiss under 5fÝm with a biopolymer, Chitosan, using supercritical CO2 as one of the solvents. In order to reach this goal, some the following initial tasks were completed: the cloud point for the system DMSO-CO2 was determined and compared with published data to validate the experimental system. Subsequently the cloud point experiments were extended to include the ternary system Chitosan-DMSO-CO2, and a dynamic solubility experimental set-up was constructed and used to obtain solubility data for the same ternary system. A novel SCF fluidized bed was used to micro encapsulate porous (TiO2) and non-porous pthesiss (CaO) through a temperature swing with a Chitosan thin layer. DMSO was used as an entrainer to enable solubilization of Chitosan and removed within the supercritical carbon dioxide. Several analytical methods were used to characterize these pthesiss; SEM-EDS analysis was used to evaluate a group of pthesiss, determining composition and pthesis diameter on samples up to 900 pthesiss. TEM and AFM confirmed pthesiss of one micron or less were encapsulated with a thickness of less than 5 nm. AFM shows pthesis roughness on the nanometer range, 46 nm or more for uncoated pthesiss and 2-4 nm for the encapsulated ones. FTIR, NMR and DSC-TGA analysis confirmed that the chemical structure of Chitosan remained constant before and after processing, and the changes observed were attributed to some DMSO and moisture adsorbed during the encapsulation process.

<p>The study introduces and puts forward Sector Policing as a model to expand community Policing and to broaden the scope of crime prevention. It also demonstrates how Sector Policing can be utilised to decentralise policing and deepen community participation.</p>

Magister Scientiae - MSc / The study introduces and puts forward Sector Policing as a model to expand community Policing and to broaden the scope of crime prevention. It also demonstrates how Sector Policing can be utilised to decentralise policing and deepen community participation. / South Africa

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