Toxicological assessment of industrial solvents using human cell bioassays: assessment of short-term cytotoxicity and long-term genotoxicity potential

There is an increasing demand for simple toxicological screening methods to assess the human health risk associated with exposure to environmental toxicants. Such screening tools should allow for risk evaluation in terms of both short-term/acute toxicity and longer-term genetic damage, which may lead to mutagenicity and carcinogenicity. We employed a battery of human cell bioassays using the human hepatoma cell-line, HepG2, to assess the cytotoxic and genotoxic potential of environmental pollutants. Here, we demonstrate direct application of these human cell bioassays to the toxicological assessment of a number of industrial solvents that are in common use worldwide. HepG2 cells were exposed to various solvents at concentrations ranging from 25 to 500 ppm. The cells were then analysed using specific protocols for four different adverse effects: cell death/acute cytotoxicity using a neutral red uptake assay, altered enzyme function (often an indicator of cell stress) using the ethoxyresorufin O-deethylase (EROD) bioassay, DNA single strand breaks (SSB), and DNA repair induction, which evaluates mutagenic activity. Using the positive controls, linear dose-response curves were achieved for all four bioassays. The high sensitivity of the tests allowed for environmentally meaningful assessments, and precision studies showed excellent reproducibility for all four bioassays. Comparing the results of the four bioassays on each of 16 industrial solvents allowed for ranking of the anticipated relative human toxicity of these solvents, which were comparable with data from standard toxicity tests and human occupational data. Overall, the study clearly supports the application of the HepG2 cell bioassay system for rapid toxicological screening of many candidate toxicants for both short- and long-term toxicity potential.     

Disparate activation of the coronary sinus and inferior left atrium during atrial tachycardia after persistent atrial fibrillation ablation: prevalence, pitfalls, and impact on mapping

Partial Coronary Sinus Disconnection During Atrial Tachycardia . Introduction: Persistent atrial fibrillation (AF) ablation may lead to partial disconnection of the coronary sinus (CS). As a result, disparate activation sequences of the local CS versus contiguous left atrium (LA) may be observed during atrial tachycardia (AT). We aimed to evaluate the prevalence of this phenomenon and its impact on activation mapping. Methods: AT occurring after persistent AF ablation were investigated in 74 consecutive patients. Partial CS disconnection during AT was suspected when double potentials with disparate activation sequences were observed on the CS catheter. Endocardial mapping facing CS bipoles was performed to differentiate LA far‐field from local CS potentials. Results: A total of 149 ATs were observed. Disparate LA–CS activations were apparent in 20 ATs after magnifying the recording scale (13%). The most common pattern (90%) was distal to proximal endocardial LA activation against proximal to distal CS activation, the latter involving the whole CS or its distal part. Perimitral macroreentry was more common when disparate LA–CS activations were observed (67% vs 29%; P = 0.002). Partial CS disconnection also resulted in “pseudo” mitral isthmus (MI) block during LA appendage pacing in 20% of patients as local CS activation was proximal to distal despite distal to proximal activation of the contiguous LA. Conclusion: Careful analysis of CS recordings during AT following persistent AF ablation often reveals disparate patterns of activation. Recognizing when endocardial LA activation occurs in the opposite direction to the more obvious local CS signals is critical to avoid misleading interpretations during mapping of AT and evaluation of MI block. (J Cardiovasc Electrophysiol, Vol. 23, pp. 697‐707, July 2012)     

A Review of Different Aspects of Applying Asphalt and Bituminous Mixes under a Railway Track

Asphalt is a common material that is used extensively for roadways. Furthermore, bituminous mixes have been used in railways, both as asphalt and as mortar. Different agencies and research institutes have investigated and suggested various applications. These studies indicate the benefits of bituminous material under railways, such as improving a substructure’s stiffness and bearing capacity; enhancing its dynamic characteristics and response, especially under high-speed train loads; waterproofing the subgrade; protecting the top layers against fine contamination. These potential applications can improve the overall track structure performance and lead to minimizing settlement under heavy loads. They can also guarantee an appropriate response under high-speed loads, especially in comparison to a rigid slab track. This review paper documents the literature related to the utilization of asphalt and bituminous mixes in railway tracks. This paper presents a critical review of the research in the application of asphalt and bituminous mixes in railway tracks. Additionally, this paper reviews the design and construction recommendations and procedures for asphalt and bituminous mixes in railway tracks as practiced in different countries. This paper also provides case studies of projects where asphalt and bituminous mixes have been utilized in railway tracks. It is anticipated that this review paper will facilitate (1) the exchange of ideas and innovations in the area of the design and construction of railway tracks and (2) the development of unified standards for the design and construction of railway tracks with asphalt and bituminous mixtures.     

Two-stage revision surgery for infected total knee replacements: reasonable function and high success rate with the use of primary knee replacement implants as temporary spacers

Two-stage revision surgery for infected total knee replacements remains the gold standard treatment. Articulating spacers are preferred to static spacers for improved functional outcome. Articulating spacers made of cement can be prone to fracture, may not be suitable for full weight bearing, create abrasion debris and necessitate second-stage revision surgery. An alternative is the use of primary knee replacement implants as temporary spacers. With this technique, implants are loosely cemented into place at time of revision, allow the patient reasonable mobility and an ability to fully weight bear and can obviate the need for second-stage surgery. A retrospective review of all patients undergoing revision for infection over two years was conducted. Patients were clinically assigned to single- or two-stage revision. Patients who had a temporary knee replacement, that is, a primary knee replacement used as an articulating spacer, were identified and contacted to complete an Oxford Knee Score. Time to second stage and recurrence was identified from the notes 23 patients received temporary knee replacements. Of these, one patient died, 13 proceeded to a second-stage revision and nine remain in situ. Median time to second-stage revision was 19 weeks [range 11–27]. No patients had re-infection. Median follow-up for ongoing temporary knee replacements was 43 weeks [range 24–90]. Four temporary implants had survived for longer than 1 year. Median Oxford Knee Score was 26 [23–32] and satisfaction score was 8 out of 10 [8–8]. These early results show that knee replacement implants used as spacers provide a good alternative to cement-based articulating spacers with low re-infection rates. Their additional cost when compared with cement spacers is offset by the fact that many patients achieve adequate function and frail patients can avoid a revision procedure. Level of evidence Case series, Level IV.