Microbial community dynamics in Inferno Crater Lake, a thermally fluctuating geothermal spring.

Understanding how microbial communities respond and adjust to ecosystem perturbation is often difficult to interpret due to multiple and often simultaneous variations in observed conditions. In this research, we investigated the microbial community dynamics of Inferno Crater Lake, an acidic geothermal spring in New Zealand with a unique thermal cycle that varies between 30 and 80 °C over a period of 40-60 days. Using a combination of next-generation sequencing, geochemical analysis and quantitative PCR we found that the microbial community composition was predominantly chemolithotrophic and strongly associated with the thermal cycle. At temperatures >65 °C, the microbial community was dominated almost exclusively by sulphur-oxidising archaea (Sulfolobus-like spp.). By contrast, at mesophilic temperatures the community structure was more mixed, comprising both archaea and bacteria but dominated primarily by chemolithotrophic sulphur and hydrogen oxidisers. Multivariate analysis of physicochemical data confirmed that temperature was the only significant variable associated with community turnover. This research contributes to our understanding of microbial community dynamics in variable environments, using a naturally alternating system as a model and extends our limited knowledge of acidophile ecology in geothermal habitats.

Biosimilar monoclonal antibodies: A Canadian regulatory perspective on the assessment of clinically relevant differences and indication extrapolation.

Monoclonal antibodies have become mainstays of treatment for many diseases. After more than a decade on the Canadian market, a number of authorized monoclonal antibody products are facing patent expiry. Given their success, most notably in the areas of oncology and autoimmune disease, pharmaceutical and biotechnology companies are eager to produce their own biosimilar versions and have begun manufacturing and testing for a variety of monoclonal antibody products. In October of 2013, the first biosimilar monoclonal antibody products were approved by the European Medicines Agency (Remsima™ and Inflectra™). These products were authorized by Health Canada shortly after; however, while the EMA allowed for extrapolation to all of the indications held by the reference product, Health Canada limited extrapolation to a subset of the indications held by the reference product, Remicade®. The purpose of this review is to discuss the Canadian regulatory framework for the authorization of biosimilar mAbs with specific discussion around the clinical requirements for establishing (bio)-similarity and to present the principles that are used in the clinical assessment of New Drug Submissions for intended biosimilar monoclonal antibodies. Health Canada's current views regarding indication extrapolation, product interchangeability, and post-market surveillance are discussed as well.

APM2 is a novel mediator of cisplatin resistance in a variety of cancer cell types regardless of p53 or MMR status.

Cisplatin is one of the most widely used chemotherapeutics in the world today. Unfortunately, chemoresistance often develops hindering the effectiveness of the drug. Mismatch-repair (MMR) and p53 have previously been shown to be important determinants of cisplatin resistance and can contribute to cisplatin resistance clinically. Here, we have used cDNA microarray to identify several genes as up or downregulated in a previously described, cisplatin resistant, clone of the HCT116 cell line (HCT116-K). On follow-up, one gene, APM2, was found to promote cisplatin resistance when overexpressed in sensitive HCT116 clones. Furthermore, silencing APM2 in a panel of cell lines encompassing all combinations of p53 status and MMR proficiency (HCT116-K, HCT116, SW620, MCF7, PC-3 and OV2008) resulted in sensitization regardless of these 2 factors. In addition, silencing APM2 stably using shRNA also resulted in the sensitization of cells to cisplatin. More importantly, cisplatin inhibited the growth of APM2 silenced tumor xenografts (HCT116-K or OV2008 cells) significantly better than it inhibited the growth of xenografts carrying nontargeting control shRNAs. These findings represent a novel strategy that could be exploited to overcome cisplatin resistance in patients regardless of p53 status or ability to perform MMR.

Transcriptomic profiling of radiation-resistant or -sensitive human colorectal cancer cells: acute effects of a single X-radiation dose.

We previously isolated several clones that were closely-related genetically from a human colorectal tumor (HCT116) cell line. These clones displayed significantly different X-radiation response phenotypes. In this paper, we investigated how a single dose of X-radiation modulated the transcriptomic profiles of either the radiation-resistant (HCT116Clone2_XRR) or the radiation-sensitive (HCT116CloneK_XRS) clone when each was compared to a reference clone, HCT116Clone10_control. The latter represented a control clone that displayed a similar X-radiation response as the parental HCT116 cells. Pooled RNAs were obtained from HCT116Clone2_XRR, HCT116CloneK_XRS or HCT116Clone10_control cells either before or at 10 min, 6 or 24 h after treatment with 4-Gy X-radiation. Transcriptomic profiles were assessed by cDNA microarrays. At least three independent experiments were carried out for each time point and statistical analysis was performed by paired t-test (p<0.05). From 19,200 genes/ESTs examined, we identified only 120 genes/ESTs that were differentially expressed at any one of these four time points. Interestingly, different patterns of gene modulation were observed between the radiation-sensitive and radiation-resistant clones. However, the fold changes of gene modulation were generally small (2-3 fold). Surprisingly, only 12.7% of 79 genes involved in DNA damage sensor/repair and cell cycle and between 2.6 and 9.2% of 76 genes involved in apoptosis, were significantly modulated in these early time points following irradiation. By comparison, up to 10% of 40 known housekeeping genes were differentially expressed. Thus in our experimental model, we were able to detect the up-regulation or down-regulation of mostly novel genes and/or pathways in the acute period (up to 24 h) following a single dose of 4-Gy X-radiation.

Geothermal ground gas emissions and indoor air pollution in Rotorua, New Zealand.

The emission of toxic gases from the soil is a hazard in geothermal regions that are also urbanized because buildings constructed on geothermal ground may be subject to the ingress of gases from the soil directly into the structure. The Rotorua geothermal field, New Zealand, is extensively urbanized but to date no studies have evaluated the extent of the ground gas hazard. The main gases emitted are hydrogen sulphide (H2S) and carbon dioxide (CO2), both of which are highly toxic and denser than air. This paper reports preliminary findings from a study of selected buildings constructed in the gas anomaly area. Properties were investigated for evidence of ingress by H2S, CO2, and 222Rn, with a view to determine the means and rates of gas entry and the nature of any consequent hazard. H2S and CO2 were investigated using infrared active gas analysers and passive detector tubes left in place for 10-48 h. 222Rn was measured over a period of 3 months by poly-allyl diglycol carbonate sensors. Eight of the nine buildings studied were found to suffer problems with soil gases entering the indoor air through the structure. The primary means of gas entry was directly from the ground through the floors, walls, and subsurface pipes. Indoor vents were located and found emitting up to approximately 200 ppm H2S and approximately 15% CO2, concentrations high enough to present an acute respiratory hazard to persons close to the vent (e.g., children playing at floor level). In some properties, gas problems occurred despite preventative measures having been made during construction or during later renovations. Typically, these measures include the under-laying of concrete floors with a gas-proof butanol seal, under-floor ventilation systems or the installation of positive-pressure air conditioning. Recently constructed buildings (<10 years) with butanol seals were nevertheless affected by ground gas emissions, and we conclude that such measures are not always effective in the long term.