Changes in mitochondrial DNA in peripheral blood mononuclear cells from HIV-infected patients with lipoatrophy randomized to receive abacavir

It has been suggested that lipoatrophy associated with exposure to nucleoside analogues is caused by depletion of mitochondrial DNA (mtDNA). The aim of the present study was to determine whether switching treatment from a thymidine analogue to abacavir was associated with an increase in the mtDNA copy number in peripheral blood mononuclear cells (PBMCs). Of 111 patients with lipoatrophy who were randomized to have treatment switched to abacavir or to continue treatment with thymidine analogues, 94 patients had PBMCs obtained at baseline and at weeks 4, 12, and 24, for quantification of the mtDNA copy number. During the 24-week study, there was no significant change in mtDNA copy numbers in PBMCs in either treatment group, despite improvement in peripheral lipoatrophy among patients whose treatment was switched to abacavir.     

Functional and comparative metagenomic analysis of bile salt hydrolase activity in the human gut microbiome

Bile salt hydrolases (BSHs) catalyze the “gateway” reaction in a wider pathway of bile acid modification by the gut microbiota. Because bile acids function as signaling molecules regulating their own biosynthesis, lipid absorption, cholesterol homeostasis, and local mucosal defenses in the intestine, microbial BSH activity has the potential to greatly influence host physiology. However, the function, distribution, and abundance of BSH enzymes in the gut community are unknown. Here, we show that BSH activity is a conserved microbial adaptation to the human gut environment with a high level of redundancy in this ecosystem. Through metagenomic analyses we identified functional BSH in all major bacterial divisions and archaeal species in the gut and demonstrate that BSH is enriched in the human gut microbiome. Phylogenetic analysis illustrates that selective pressure in the form of conjugated bile acid has driven the evolution of members of the Ntn_CGH-like family of proteins toward BSH activity in gut-associated species. Furthermore, we demonstrate that BSH mediates bile tolerance in vitro and enhances survival in the murine gut in vivo. Overall, we demonstrate the use of function-driven metagenomics to identify functional anchors in complex microbial communities, and dissect the gut microbiome according to activities relevant to survival in the mammalian gastrointestinal tract.     

Mobile genetic elements of the human gastrointestinal tract

The human intestine is an important location for horizontal gene transfer (HGT) due to the presence of a densely populated community of microorganisms which are essential to the health of the human superorganism. HGT in this niche has the potential to influence the evolution of members of this microbial community and to mediate the spread of antibiotic resistance genes from commensal organisms to potential pathogens. Recent culture-independent techniques and metagenomic studies have provided an insight into the distribution of mobile genetic elements (MGEs) and the extent of HGT in the human gastrointestinal tract. In this mini-review, we explore the current knowledge of mobile genetic elements in the gastrointestinal tract, the progress of research into the distribution of antibiotic resistance genes in the gut and the potential role of MGEs in the spread of antibiotic resistance. In the face of reduced treatment options for many clinical infections, understanding environmental and commensal antibiotic resistance and spread is critical to the future development of meaningful and long lasting anti-microbial therapies.     

Impact of plasmid stability on oral DNA delivery by Salmonella enterica serovar Typhimurium

Live attenuated Salmonellae may overcome limitations with conventional methods of DNA immunisation. This study examined the impact of plasmid stability on oral DNA delivery by the attenuated Salmonella enterica serovar Typhimurium vaccine strain BRD509. A DNA vaccine cassette comprising the C fragment of tetanus toxin under control of the cytomegalovirus (CMV) promoter was ligated into plasmid pcDNA3, pUC18, pBBR122, pACYC184, pRSF1010/CAT, pBR322 and pAT153. In vitro and in vivo stability studies revealed that, with the exception of pcDNA3 and pUC18, the plasmids were retained by BRD509. However, pAT153 was the only plasmid to induce a tetanus toxoid-specific antibody response following oral delivery. Plasmid copy number was found to impact on plasmid stability and the induction of antigen-specific humoral responses.     

Conservative aesthetic techniques for discoloured teeth: 1. The use of bleaching

There is an increasing move towards more minimally invasive techniques in restorative dentistry. This series of two articles discusses conservative techniques for the treatment of discoloured teeth. A step-wise approach to treatment is promoted to encourage the most conservative solution to achieve satisfactory aesthetics. The first of these two articles will describe the use of bleaching, whilst part two will go on to describe microabrasion and the use of direct composite resin. Clinical Relevance: Discoloured teeth are a common dental problem. Bleaching provides a simple conservative solution in many cases.     

Automating direct-to-PCR for disaster victim identification

ABSTRACT

Direct-to-PCR methodology adds samples directly to PCR tubes offering gains in efficiency and sensitivity. The approach has been applied to a variety of biological sources including blood, saliva, tissue, hair and nail. We added various preservative solutions to a range of biological samples to leech DNA into solution, whilst preserving at room temperature. Tubes containing ‘free DNA’ then followed automated workflows for amplification and capillary electrophoresis. Routine FASS-automated workflows (including DNA extraction and quantification) were compared with published direct-to-PCR methodology and automated amplification of an aliquot of preservative solution. Applying preservative solutions to ~30-year-old blood stains stored at room temperature resulted in recovery of a larger quantity of DNA and more alleles (using PowerPlex 21) when compared with routine automated typing. Trials were extended to blood, saliva, hair and nail, mimicking ante-mortem samples collected in a disaster victim identification effort. Despite slightly lower allelic recovery, the faster processing times, lower costs and storage potential offers advantages for the processing of ante-mortem samples.     

Why do we need a systems thinking approach to military forensic science in the contemporary world?

ABSTRACT

The Australian threat environment has changed as a result of global terrorism and foreign fighters, which are contributing factors to the blurring of the lines between military objectives and law enforcement activities. This shift requires a more integrated and interoperable forensic science framework that is coordinated at the whole-of-Government enterprise level. The forensic science ‘system of systems’ provides an integrating framework, which recognizes that forensic science supports the criminal justice, law enforcement, intelligence, and military systems. These systems must work together to achieve end-to-end performance, which is coordinated through integration and sharing of information across the systems. The purpose of this paper is to discuss why we need a systems thinking approach to military forensic science in the contemporary world. Implementation of a coordinated and interoperable military forensic science system of systems will contribute to the Australian Department of Defence strategic objective to deter, deny and defeat returned foreign fighters and global terrorist networks, such as Islamic State of Iraq and Syria (ISIS).