Evaluation of the ability of commercial disinfectants to degrade free nucleic acid commonly targeted using molecular diagnostics

BACKGROUND

Polymerase chain reaction (PCR) is an essential tool for rapid detection of pathogens, but is susceptible to cross-contamination by residual nucleic acid, leading to false-positive results. Adequate surface decontamination would help prevent this, but most protocols target infectious microbes rather than free nucleic acid. The aim of this study was to evaluate the ability of commercial surface disinfectants to degrade different representative classes of nucleic acid.

METHODS

Commercial surface disinfectants with various active ingredients, as well as 10% chlorine bleach, were tested. Nucleic acid was dried on to stainless steel coupons and treated with disinfectant for 0-4 min prior to neutralization and quantification by quantitative reverse transcription PCR. The effective disinfectants were also evaluated in the presence of organic load.

RESULTS

Only dilute chlorine bleach and the hypochlorite-based commercial disinfectant significantly degraded any type of free nucleic acid. Hydrogen-peroxide- and quaternary-ammonium-based disinfectants gave <1 log reduction after 4 min for all targets. Results were time-dependent for each target, which underscores the importance of adequate contact time. Organic load appeared to have little impact on the efficacy of hypochlorite-based disinfectants for nucleic acid degradation.

CONCLUSIONS

This study demonstrates the importance of proper selection and application of disinfectant to remove residual nucleic acid when processing samples for molecular diagnostic testing.

Qualitative Exploration Toward the Development of a Parent-Rated Scale for Insomnia in Children with Autism Spectrum Disorder

Toward the development of a new parent-rating for insomnia, this multi-site qualitative study explored sleep problems and related impacts in children with autism spectrum disorder (ASD) and their families. To ensure content validity of the measure, we conducted six focus groups with caregivers (N = 25) of 24 children (age 3 to 18 years) with ASD. Based on parent report, all children had a history of mild or greater insomnia. The focus group transcripts were systematically coded to identify major themes. Verbatim comments from caretakers were used to generate 134 candidate items. Further review by the research team and an expert panel followed by individual cognitive interviews with 12 parents reduced the item bank to 40. The thematic analysis of focus group transcripts identified 7 categories: (1) Trouble falling asleep; (2) trouble staying asleep; (3) early morning waking; (4) bedtime routines; (5) parental strategies for bedtime management; (6) impact of sleep problems on the child; and (7) impact of sleep problems on the family. The Flesch Kincaid Grade Level of the 40-item version was 7.2 (seventh grade reading level). Insomnia in children with ASD shares features in common with insomnia in the general pediatric population. However, perhaps owing to autistic features such as insistence on sameness, sensory sensitivities, communication impairments, insomnia in children with ASD appears to have unique behavioral manifestations. Content validity and item clarity of the 40-item bank were supported by expert panel review and cognitive interviews with caregivers of children with ASD.

Efficacy of novel aqueous photo-chlorine dioxide against a human norovirus surrogate, bacteriophage MS2 and Clostridium difficile endospores, in suspension, on stainless steel and under greenhouse conditions

AIMS

The efficacy of a novel photochemical method for generating chlorine dioxide (photoClO₂ ) was evaluated against human noroviruses (HuNoV) surrogate, bacteriophage MS2, and Clostridium difficile endospores.

METHODS AND RESULTS

Chlorine dioxide was generated by mixing 1% sodium chlorite with 10 parts-per-million (ppm) Eosin Y and irradiating with a photo-activator-excitable light. PhotoClO₂ efficacy was assessed against bacteriophage MS2 and C. difficile endospores in suspension, on hard surfaces and greenhouse conditions under soiled and unsoiled conditions. The estimated effective photoClO₂ produced and consumed was 20·39 ± 0·16 ppm at a rate of 8·16 ppm per min in a 1% sodium chlorite solution. In suspension, MS2 phage was reduced by 3·35 and >5·10 log₁₀ PFU per ml in 120 and 90 min, with and without soil, respectively. At the same time, when dried on stainless steel surface, MS2 phage was reduced by >4·53 log₁₀ PFU per carrier in 30 min under both conditions. On the other hand, C. difficile endospores in suspension were reduced by 2·26 and 3·65 log₁₀ CFU per ml in 120 min with and without soiling, respectively. However, on stainless steel surface, maximal reductions of the C. difficile endospores were 0·8 and 1·5 log₁₀ CFU per carrier with and without soiling, respectively, and a maximal reduction of 2·97 log₁₀ CFU per carrier under greenhouse conditions at 24 h.

CONCLUSIONS

Overall, photoClO₂ showed promise as a technology to control HuNoV contamination on environmental surfaces but requires further optimization and testing against C. difficile endospores.

SIGNIFICANCE AND IMPACT OF THE STUDY

Results from this investigation will serve as a model for how to generate and quantify photoClO₂ and how to appropriately evaluate this new class of disinfectants against environmentally resilient pathogens: viruses and bacterial endospores.

Stevens - Johnson Syndrome Induced by Combination of Lamotrigine and Valproic Acid in a 9-Year-Old Boy

We describe the case history of a 9-year-old boy who developed Stevens-Johnson syndrome (SJS) following concomitant use of valproic acid and lamotrigine. He presented with rash and fever several weeks after introduction of lamotrigine, having been on valproic acid for seizure disorder. SJS happens to be one of the rare adverse reactions of antiepilepsy drugs (AED). Management is mainly supportive with care escalation when necessary because of the significant morbidity.

Why Do Some People Take a Long Time to See Complex Random-Dot Stereograms?

Some observers take a long time to see the appropriate surface shapes depicted in complex random-dot stereograms (RDSs) whereas others report seeing them quickly. We have hypothesised that this may be due in part to some observers being more affected than others by the cue conflicts that are typically present in RDSs, for which disparity is often at odds with accommodation, texture, and outline shape cues.

We report two experiments in which we investigated whether a measure of dominance of texture/outline cues over disparity cues in stereograms of ridges could predict latencies to see RDSs of ‘wedding cakes’ viewed from above. Latencies were measured for correctly reporting the number of layers in the wedding cakes. The ridge cue dominance index was obtained by using amplitude judgements of convex parabolic vertical and horizontal ridge stereograms embodying texture/outline vs disparity cue conflicts (Buckley and Frisby, 1993 Vision Research33 919 – 934). In the first experiment ( N=38) disparity cues in the wedding cakes were depicted with inconsistent dot texture elements, ie the dots signalled flatness as there were no density differences between the cake layers. Observers giving greater weight to texture/outline in the vertical-ridge amplitude task showed significantly longer latencies to the wedding cakes. In a second experiment with different observers ( N=35), 18 were shown wedding cakes with textures consistent with disparity (diamonds drawn with correct perspective and density) and 17 saw the same disparity cues carried by inconsistent textures (diamonds signalling flatness). Large and significant correlations were found between the cue dominance index from vertical ridges and the latencies to wedding cakes depicted with inconsistent textures: observers with higher texture/outline cue dominance showed longer latencies. This result was remarkable given the lack of any readily apparent differences between the consistent and inconsistent textures in the wedding-cake stimuli. Equivalent correlations for wedding cakes depicted with consistent textures were small and nonsignificant. We conclude that individual differences in latencies to complex RDSs can be partly explained by differences in observers' susceptibility to texture/disparity cue conflicts embodied in those RDSs.

Targeting Mdmx to treat breast cancers with wild-type p53

The function of the tumor suppressor p53 is universally compromised in cancers. It is the most frequently mutated gene in human cancers (reviewed). In cases where p53 is not mutated, alternative regulatory pathways inactivate its tumor suppressive functions. This is primarily achieved through elevation in the expression of the key inhibitors of p53: Mdm2 or Mdmx (also called Mdm4) (reviewed). In breast cancer (BrCa), the frequency of p53 mutations varies markedly between the different subtypes, with basal-like BrCas bearing a high frequency of p53 mutations, whereas luminal BrCas generally express wild-type (wt) p53. Here we show that Mdmx is unexpectedly highly expressed in normal breast epithelial cells and its expression is further elevated in most luminal BrCas, whereas p53 expression is generally low, consistent with wt p53 status. Inducible knockdown (KD) of Mdmx in luminal BrCa MCF-7 cells impedes the growth of these cells in culture, in a p53-dependent manner. Importantly, KD of Mdmx in orthotopic xenograft transplants resulted in growth inhibition associated with prolonged survival, both in a preventative model and also in a treatment model. Growth impediment in response to Mdmx KD was associated with cellular senescence. The growth inhibitory capacity of Mdmx KD was recapitulated in an additional luminal BrCa cell line MPE600, which expresses wt p53. Further, the growth inhibitory capacity of Mdmx KD was also demonstrated in the wt p53 basal-like cell line SKBR7 line. These results identify Mdmx growth dependency in wt p53 expressing BrCas, across a range of subtypes. Based on our findings, we propose that Mdmx targeting is an attractive strategy for treating BrCas harboring wt p53.

Evaluation of local anaesthetic infiltration for cryosurgery of hand warts: a prospective comparative study

BACKGROUND

The pain of cryosurgery for hand warts can lead to poor patient satisfaction and inadequate response to treatment.

AIM

To determine if local anaesthetic infiltration using a 30-gauge needle prior to cryosurgery is acceptable to patients.

METHOD

20 consecutive patients were recruited over a 14-month period who attended a cryosurgery clinic and who had at least two warts between 5 and 10 mm in diameter on different parts of the hands. In each patient, two warts of approximately equal size were treated using standard cryosurgery techniques, one under local anaesthetic (LA) and the other without.

RESULTS

The average pain score of cryosurgery without LA was more than twice the pain score of administering the LA with a 30-gauge needle (p < 0.0005). One out of 20 warts failed to clear in the LA-treated group and 2 out of 20 warts failed to clear in the non-LA-treated group.

CONCLUSIONS

This research suggests that for the majority of patients with warts between five and ten millimetres in diameter, cryosurgery is significantly less painful when carried out under LA.

The marketing of herd health and production management services on Dutch dairy farms: perceptions of dairy farmers and their veterinary surgeons

A questionnaire-based survey on veterinary herd health and production management services was conducted on 194 specialist dairy veterinarians and 466 dairy farmers. The farmers were randomly selected from greater than 6,000 farmer clients of the surveyed veterinarians. This paper reports these survey findings and the findings of an earlier survey conducted among the veterinarians. The survey included questions on the attributes of the service itself, the practitioners delivering the service, reasons for participation and the expected future of herd health and production management services. Reasons farmers participated in herd health and production management programmes included; access to routine screening of their herd; increasing profits; and receiving regular veterinary advice or solutions to remedy existing problems. Advantages of participation named included: good management support; higher profits; structural solutions to problems; and being better informed. Differences between farming styles were observed, pointing to the different needs and goals of farming styles. Farmers cited high costs and the time investment required as major disadvantages. The proportion of farmers citing these reasons was lower than expected by the veterinarians. In the future, preventive healthcare will be the main reason of farmers to participate. Farmers who are not using the service can potentially be encouraged to engage the services after gaining increased insight into the herd health and management service structure, the planning of activities, the cost-benefit of the service, veterinary surgeons being more co-operative with other farm advisors and veterinarians being more willing to pay attention to quality issues on the dairy farm.

Performance of an electron cyclotron resonance ion source designed for isotope ratio mass spectrometry

We have designed, built, and tested an electron cyclotron resonance ion source suited to the needs of an experimental program examining new methods of isotope ratio mass spectrometry using multiply charged ions. Contaminant levels have been reduced to low levels. Sample absorption and desorption effects are under investigation and preliminary results are presented.

Mitochondrial DNA phylogeography of Lissotriton boscai (Caudata, Salamandridae): evidence for old, multiple refugia in an Iberian endemic

In Europe, southern peninsulas served as refugia during cold periods in the Pleistocene, acting both as centres of origin of endemisms and as sources from which formerly glaciated areas were recolonized during interglacial periods. Previous studies have revealed that within the main refugial areas, intraspecific lineages often survived in allopatric refugia. We analysed two mitochondrial markers (nad4, control region, approximately 1.4 kb) in 103 individuals representing the entire distribution of Lissotriton boscai, a newt endemic to the western Iberian Peninsula. We inferred the evolutionary history of the species through phylogenetic, phylogeographic and historical demographic analyses. The results revealed unexpected, deep levels of geographically structured genetic variability. We identified two main evolutionary lineages, each containing three well-supported clades. The first historical split involved populations from central-southwestern coastal Portugal and the ancestor of all the remaining populations around 5.8 million years ago. Both lineages were subsequently fragmented into different population groups between 2.5 and 1.2 million years ago. According to nested clade analysis, at lower hierarchical levels the patterns suggest restricted gene flow with isolation by distance, whereas at higher levels the clades exhibit signatures of contiguous range expansion. Bayesian Skyline Plots show recent bottlenecks, followed by demographic expansions in all lineages. The significant genetic structure found is consistent with long-term survival of populations in allopatric refugia, supporting the 'refugia-within-refugia' scenario for southern European peninsulas. The comparison of our results with other co-distributed species highlights the generality of this hypothesis for the Iberian herpetofauna and suggests that Mediterranean refuges had more relevance for the composition and distribution of present biodiversity patterns than currently acknowledged. We briefly discuss the taxonomic and conservation implications of our results.

Scan of human genome reveals no new Loci under ancient balancing selection

There has been much speculation as to what role balancing selection has played in evolution. In an attempt to identify regions, such as HLA, at which polymorphism has been maintained in the human population for millions of years, we scanned the human genome for regions of high SNP density. We found 16 regions that, outside of HLA and ABO, are the most highly polymorphic regions yet described; however, evidence for balancing selection at these sites is notably lacking--indeed, whole-genome simulations indicate that our findings are expected under neutrality. We propose that (i) because it is rarely stable, long-term balancing selection is an evolutionary oddity, and (ii) when a balanced polymorphism is ancient in origin, the requirements for detection by means of SNP data alone will rarely be met.

Observational study of bone-anchored hearing aid infection rates using different post-operative dressings

Introduction: Avoidance of infection at the implant site is a crucial element to the success of bone-anchored hearing aid (BAHA) implantation. However, little evidence exists to suggest the best post-operative wound dressing to use.

Material and methods: We report our experience with 160 consecutive BAHA patients, using four types of post-operative BAHA wound dressing (Tri-adcortyl®, Mepitel®, Allevyn®, and Acticoat 7® with Allevyn). Patients were reviewed at week one and week two post-operatively. Infection was defined as a positive wound swab culture or evidence of cellulitis at the BAHA site.

Results: Post-operative BAHA infection rates were 16 per cent, 50 per cent, 10 per cent and 5 per cent, for each of the four dressings respectively, and the mean number of additional visits to wound care clinic were 1.5, 3.7, one and 0.4, respectively.

Discussion: Acticoat 7 with Allevyn produced the lowest infection rate and thus became the dressing of choice for our BAHA programme.

The DNA sequence and biological annotation of human chromosome 1

The reference sequence for each human chromosome provides the framework for understanding genome function, variation and evolution. Here we report the finished sequence and biological annotation of human chromosome 1. Chromosome 1 is gene-dense, with 3,141 genes and 991 pseudogenes, and many coding sequences overlap. Rearrangements and mutations of chromosome 1 are prevalent in cancer and many other diseases. Patterns of sequence variation reveal signals of recent selection in specific genes that may contribute to human fitness, and also in regions where no function is evident. Fine-scale recombination occurs in hotspots of varying intensity along the sequence, and is enriched near genes. These and other studies of human biology and disease encoded within chromosome 1 are made possible with the highly accurate annotated sequence, as part of the completed set of chromosome sequences that comprise the reference human genome.

Contact allergy to isoeugenol and its derivatives: problems with allergen substitution

A total of 2261 (808 male, 1453 female) consecutive patients attending contact dermatitis clinics were patch tested to isoeugenol and its derivatives listed in the EU Inventory of Fragrance Ingredients. Positive reactions were found to isoeugenol in 40, transisoeugenol in 40, isoeugenyl acetate in 19, isoeugenyl benzoate in 4, isoeugenyl phenylacetate in 16, isoeugenyl methyl ether in 6 and benzyl isoeugenyl ether in 2 patients. There was a concomitant reaction to isoeugenol in 36/40 of those positive to transisoeugenol, 13/19 of those to isoeugenyl acetate, 3/4 of those to isoeugenyl benzoate and 15/16 of those to isoeugenyl phenylacetate but in none of those 6 positive to isoeugenyl methyl ether and in neither of those 2 positive to benzyl isoeugenyl ether. Concomitant contact allergy between isoeugenol and its derivatives may occur through chemical cross-reactivity or local skin metabolism of the derivatives. It is more commonly observed with the esters rather than the ethers. Isoeugenyl acetate has been proposed as an alternative to isoeugenol, but there is a high degree of concomitant reactivity with isoeugenol.

Reaction time does not predict surgical skill

Fast is not always best

Depth cue reliance in surgeons and medical students

BACKGROUND

Depth perception is reduced in endoscopic surgery, although little is known about the effect this has on surgical performance.

METHODS

To assess the role of depth cues, 45 subjects completed tests of depth cue reliance. Surgical skill was assessed using the Minimally Invasive Surgical Trainer-Virtual Reality, a previously validated laparoscopic simulator.

RESULTS

We could demonstrate no difference in cue reliance for three depth cues--namely stereo, texture, and outline--between surgeons and medical students. Greater dominance on stereo for medical students was a positive finding and a negative finding for the surgeons when correlated with surgical performance.

CONCLUSIONS

We suggest that surgeons learn to adapt to the nonstereo environment in MIS, and this is the first study to show evidence of this phenomenon. This difference in stereo reliance is a reflection of the experience that surgeons have with laparoscopy compared with medical students, who have none.

Can tonic accommodation predict surgical performance?

BACKGROUND

Pilots undergo many visual tests for both selection and assessment, and we know that there are many similarities between pilots and surgeons. Hence, it would not be unreasonable to bring similar visual tests into surgery. Tonic accommodation (TA) is a stable parameter that is adopted by the eye in the absence of any stimulation. Over recent years, surgery has undergone change from traditional open surgery to minimally invasive procedures, bringing many advantages. However, not every surgeon has the ability to perform under conditions where the operative field is represented on a flat monitor.

METHOD

We determined the TA values in medical students and then correlated this with their performance on a virtual reality surgical simulator.

RESULTS

We found that TA values predicted the number of errors made with the dominant hand, accounting for 27% of the variance.

CONCLUSION

The data suggest that TA may play a role in the individual differences that are noted when surgeons perform laparoscopic surgery. Further studies are needed to evaluate the exact role of TA in surgical performance.

Dispersal of viviparity across contact zones in Iberian populations of fire salamanders (Salamandra) inferred from discordance of genetic and morphological traits

We used partial sequences of the cytochrome b mitochondrial DNA (mtDNA) gene, obtained from 76 individuals representing 45 populations of Iberian Salamandra salamandra plus 15 sequences of additional species of Salamandra and related genera, to investigate contact zones. These zones, identified by earlier allozymic and morphological analyses, are between populations of viviparous (S. s. bernardezi and S. s. fastuosa) and ovoviviparous (S. s. gallaica and S. s. terrestris) salamanders. The distribution of mtDNA and nuclear markers is mostly concordant at one contact zone (between S. s. gallaica and S. s. bernardezi), but at another (between S. s. fastuosa and S. s. terrestris) the markers are offset by about 250 km. The observed geographic variation fits a model of mtDNA capture. Among the potential mechanisms responsible for such discordance we favor a combination of range shifts due to climatic fluctuations and biased genetic admixture across moving contact zones. We apply our findings to the issue of possible homoplasy in the evolution of viviparity and conclude that viviparity likely arose only once within S. salamandra.