VECSEL-based virtually imaged phased array spectrometer for rapid gas phase detection in the mid-infrared.

We present a novel, to the best of our knowledge, system for high-resolution, time-resolved spectroscopy in the mid-wave infrared based on a modelocked vertical external cavity surface emitting laser (VECSEL) frequency comb coupled to a virtually imaged phased array (VIPA) spectrometer. The GHz level repetition rate of VECSEL-based systems coupled to VIPA spectrometers enables comb tooth resolved spectra without the use of additional filter cavities often required to increase comb tooth spacing. We demonstrate absorption spectroscopy on a methane (CH4) gas mixture at 2900cm-1 (3.4 µm) with over 35cm-1 spectral bandwidth in a single image. Rapid time-resolved measurements were made using a 300 µs exposure time with an acquisition rate limited to 125 Hz by the available camera. High-resolution absolute frequency measurements were performed by scanning the repetition rate of the VECSEL frequency comb.

Short-term effects of povidone iodine and sodium fluoride therapy on plaque levels and microbiome diversity.

OBJECTIVES: The objective of this study is to evaluate the effect of short-term changes in the oral microbial ecology of dental plaque and plaque levels after topical treatment of a combination of 10% povidone iodine (PI) and 5% sodium fluoride varnish (FV). MATERIALS AND METHODS: A single group design intervention study on 12 pediatric patients, who underwent two baseline plaques samplings before the intervention, were enrolled in the study. A modified mixed dentition Silness-Löe plaque index score was used to assess plaque accumulation and microbial composition was assessed by amplicon sequencing analysis of the 16S rRNA V4 region. RESULTS: Dental plaque accumulation (P = 0.0424) was reduced after 1 week using PI/FV application. This reduction was not observed between the two double-baseline visits. 16S rRNA analysis showed that the single PI/FV therapy did not have dramatic shifts in the plaque microbiome community depicted by hierarchical cluster and principle component analysis. More subtle changes were found when analyzing the Shannon diversity index after the application of PI/FV vs two baselines prior to combination therapy. CONCLUSIONS: The bacteria within the dental biofilms showed resilience in maintaining the overall community diversity but reduced biofilm accumulation following PI/FV therapy. Repeated uses of PI/FV may augment plaque control during dental rehabilitation in children.

N-Acetyl-l-cysteine effects on multi-species oral biofilm formation and bacterial ecology.

UNLABELLED: Future therapies for the treatment of dental decay have to consider the importance of preserving bacterial ecology while reducing biofilm adherence to teeth. A multi-species plaque-derived (MSPD) biofilm model was used to assess how concentrations of N-acetyl-l-cysteine (NAC) (0, 0·1, 1, 10%) affected the growth of complex oral biofilms. Biofilms were grown (n = 96) for 24 h on hydroxyapatite discs in BMM media with 0·5% sucrose. Bacterial viability and biomass formation was examined on each disc using a microtitre plate reader. In addition, fluorescence microscopy and Scanning Electron Microscopy was used to qualitatively examine the effect of NAC on bacterial biofilm aggregation, extracellular components and bacterial morphology. The total biomass was significantly decreased after exposure of both 1% (from 0·48, with a 95% confidence interval of (0·44, 0·57) to 0·35, with confidence interval (0·31, 0·38)) and 10% NAC (0·14 with confidence interval (0·11, 0·17)). 16S rRNA amplicon sequencing analysis indicated that 1% NAC reduced biofilm adherence while preserving biofilm ecology. SIGNIFICANCE AND IMPACT OF THE STUDY: As a compound with a wide safety margin, N-acetyl-l-cysteine (NAC) has the potential to be used as a long term anti-plaque bacteriostatic agent for managing chronic dental decay without substantially altering biofilm's bacterial ecology. The potential anti-caries benefit of NAC is directly related to reducing the biofilm coverage which reduces the degree of acid generation and the amount of time that the surface is exposed to a lower pH.

Biofilm community diversity after exposure to 0·4% stannous fluoride gels.

AIMS: To test the effect of 0·4% stannous fluoride (SnF2 ) glycerine-based gels on specific portions of the bacterial community in both a clinical observational study and in vitro multispecies plaque-derived (MSPD) biofilm model. METHODS AND RESULTS: Potential changes to specific portions of the bacterial community were determined through the Human Oral Microbial Identification Microarray (HOMIM). Both the observational clinical study and the biofilm model showed that short-term use of 0·4% SnF2 gel has little effect on the bacterial community depicted by hierarchical cluster analysis. The amount of plaque accumulation on a subject's teeth, which was measured by plaque index scores, failed to show statistical significant changes over the two baselines or after treatment (P = 0·9928). The in vitro results were similar when examining the effect of 0·4% SnF2 gels on biofilm adherence through a crystal violet assay (P = 0·1157). CONCLUSIONS: The bacteria within the dental biofilms showed resilience in maintaining the overall community diversity after exposure to 0·4% SnF2 topical gels. SIGNIFICANCE AND IMPACT OF THE STUDY: The study supports that the immediate benefits of using 0·4% SnF2 gels in children may be strictly from fluoride ions inhibiting tooth demineralization rather than delivering substantial antimicrobial effects.

Communication and professionalism skills of a new graduate: the expectations and experiences of dental foundation trainers.

AIM: The aim of this study was to investigate dental foundation year 1 (DF1) trainers' expectations of the dental graduate specifically in relation to non-clinical (professionalism and communication) skills and to explore whether these expectations were being met. METHOD: In the UK, dental graduates undertake 1 year of foundation training prior to being permitted to undertake NHS practice. An online survey was distributed to DF1 trainers via all 11 English deaneries and the Northern Ireland deanery. Demographic information and a general view of trainers' expectations of a new trainee were collected. Specific questions relating to six generic trainee problems were followed by 11 ability statements where trainers indicated their expectation of a trainee's ability to perform the skill on a 5-point scale (on own with confidence-unable to undertake). Statements were repeated and trainers were required to respond using the same scale in relation to experience of their current trainee. RESULTS: Five hundred and ten (53%) trainers completed the questionnaire with no missing data. Expectations were high with almost 50% of trainers expecting a new graduate to manage a full list of patients on their own. Experience of new graduates did not always match these expectations. Of concern was the ability to 'keep accurate patient records' and 'self-reflection and knowing when to seek help', where a small proportion of trainers experienced difficulties. CONCLUSIONS: Trainers' expectation and experience in relation to non-clinical skills of a new graduate were investigated. Although they had high expectations, the majority reported only minor problems overall. There were a few areas where concern was raised.

Two-stage revision for infected total knee arthroplasty: our experience with interval prosthesis.

INTRODUCTION: To review our practice of performing two-stage revision for infected total knee arthroplasty using articulating interval prosthesis and to compare the incidence of the recurrence of infection and re-operation rate in patients undergoing two-stage revision as planned with the group of patients who choose not to proceed to the second stage. METHOD: This study is a retrospective review of 60 consecutive patients undergoing a two-stage revision for infected total knee arthroplasty using articulating interval prosthesis. All cases managed by a single surgeon using a uniform peri-operative protocol, and short-course parenteral antibiotic therapy. RESULT: Thirty-four patients (57%) (Group 1) underwent the two-stage revision as planned. However, twenty-six patients (43%) (Group 2) opted not to have a second-stage procedure as the first-stage and interval prosthesis had eradicated the infection, resolved the pain and achieved good functional outcome. There were five cases of recurrent infection in the 60 patients (8%) at a mean follow-up 5 years. In those completing the two-stage revision, two patients had recurrent infection. Of the patients who retained the interval prosthesis, there were three recurrent infections. There was no statistically significant difference between the groups in terms of recurrence of infection or re-revision. CONCLUSION: Two-stage revision with interval prostheses represents a safe and reliable method of treating infected knee prosthesis; however, there may be a role for one-stage revision in selected cases.

Big brands impact small islands: Sources of plastic pollution in a remote and protected archipelago.

Remote islands are disproportionately affected by plastic pollution, often originating from elsewhere, so it is important to understand its origins, to stop debris entering the ocean at their source. We investigated the origins of beached plastic drink bottles in the Chagos Archipelago, a large remote Marine Protected Area (MPA) in the Indian Ocean. We recorded the brands, countries of manufacture, types of drink, and ages of plastic bottles and their lids. The prevalent type of drink was water, with items mostly manufactured in Indonesia, China, and the Maldives. The main brands were Danone and the Coca-Cola Company. We deduced that 10 % of the items originated from ships passing the archipelago, including all the items manufactured in China. The identification of the brands creating plastic pollution in remote MPAs with high biodiversity supports extended producer responsibility, one of the proposed policy development areas of the Global Plastics Treaty.

Automatic oral fluid-based HIV testing in HIV screening programmes: automatic for the people.

OBJECTIVES: UK guidelines recommend routine HIV testing in general clinical settings when the local HIV prevalence is > 0.2%. During pilot programmes evaluating the guidelines, we used laboratory-based testing of oral fluid from patients accepting tests. Samples (n = 3721) were tested manually using the Bio-Rad Genscreen Ultra HIV Ag-Ab test (Bio-Rad Laboratories Ltd, Hemel Hempstead, UK). This was a methodologically robust method, but handling of samples was labour intensive. We performed a validation study to ascertain whether automation of oral fluid HIV testing using the fourth-generation HIV test on the Abbott Architect (Abbott Diagnostics, Maidenhead, UK) platform was possible. METHODS: Oral fluid was collected from 143 patients (56 known HIV-positive volunteers and 87 others having contemporaneous HIV serological tests) using the Oracol+ device (Malvern Medicals, Worcester, UK). Samples were tested concurrently: manually using the Genscreen Ultra test and automatically on the Abbott Architect. RESULTS: For oral fluid, the level of agreement of results between the platforms was 100%. All results agreed with HIV serology. The use of the Oracol+ device produced high-quality samples. Subsequent field use of the test has shown a specificity of 99.97% after nearly 3000 tests. CONCLUSIONS: Laboratory-based HIV testing of oral fluid requires less training of local staff, with fewer demands on clinical time and space than near-patient testing. It is acceptable to patients. The validation exercise and subsequent clinical experience support automation, with test performance preserved. Automation reduces laboratory workload and speeds up the release of results. Automated oral fluid testing is thus a viable option for large-scale HIV screening programmes.

Mucormycosis in COVID-19 patients - A case series from a dental college in South India.

Introduction: Incidence of mucormycosis has increased recently due to rapid spread of coronavirus disease 2019 (COVID-19), which is a hyper-ferritemic state paving a way for easy growth of mucor species. COVID-19 infection results in an immunocompromised state due to the steroid therapy administered to patients and the infection itself. The presence of co-morbidities makes patients more susceptible to acquire mucor infection. Mucormycosis spreads rapidly, associated with aggressive angioinvasion, leading to ischemic necrosis of surrounding tissues. Due to its rapid spread and angioinvasion, mucormycosis is associated with increased mortality and morbidity. Treatment Planning: Early diagnosis and proper treatment planning are crucial to prevent further spread of infection, where dentists play an important role. Discussion: This case series is mainly focused on patients reported to the oral medicine department with complaints of discomfort or mobility of teeth in the maxillary region while explaining the role of dentists in diagnosing and treating the disease.

A reproducible oral microcosm biofilm model for testing dental materials.

AIMS: Most studies of biofilm effects on dental materials use single-species biofilms, or consortia. Microcosm biofilms grown directly from saliva or plaque are much more diverse, but difficult to characterize. We used the Human Oral Microbial Identification Microarray (HOMIM) to validate a reproducible oral microcosm model. METHODS AND RESULTS: Saliva and dental plaque were collected from adults and children. Hydroxyapatite and dental composite discs were inoculated with either saliva or plaque, and microcosm biofilms were grown in a CDC biofilm reactor. In later experiments, the reactor was pulsed with sucrose. DNA from inoculums and microcosms was analysed by HOMIM for 272 species. Microcosms included about 60% of species from the original inoculum. Biofilms grown on hydroxyapatite and composites were extremely similar. Sucrose pulsing decreased diversity and pH, but increased the abundance of Streptococcus and Veillonella. Biofilms from the same donor, grown at different times, clustered together. CONCLUSIONS: This model produced reproducible microcosm biofilms that were representative of the oral microbiota. Sucrose induced changes associated with dental caries. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first use of HOMIM to validate an oral microcosm model that can be used to study the effects of complex biofilms on dental materials.

Quantifying dental biofilm growth using cross-polarization optical coherence tomography.

AIMS: Quantifying the ex vivo growth of complex multispecies dental biofilms using cross-polarization 1310-nm optical coherence tomography (CP-OCT) system was investigated. METHODS AND RESULTS: Bacterial microcosms, which were derived from plaque samples of paediatric subjects, were incubated in a biofilm reactor system containing discs of different dental materials for 72 h with daily sucrose pulsing (5×). CP-OCT analysis of biofilm mass was validated with crystal violet (CV) assays at various growth stages of these complex biofilms. CP-OCT was able to filter out the back-reflected signals of water layers in the hydrated biofilm and allowed for direct biofilm quantification. The overall depth-resolved scattering intensity of the biofilm showed very strong positive correlation with CV assay quantification (Spearman's ρ = 0.92) during the growth phase of the biofilm. CONCLUSION: CP-OCT was able to quantify the mass of the biofilm by measuring the overall depth-resolved scattering of the biofilm. SIGNIFICANCE AND IMPACT OF THE STUDY: CP-OCT has the ability to nondestructively monitor biofilm growth and elucidate the growth characteristics of these microcosms on different dental material compositions.

Spatial variation of plastic debris on important turtle nesting beaches of the remote Chagos Archipelago, Indian Ocean.

We report Anthropogenic Marine Debris (AMD) in Chagos Archipelago in the Indian Ocean, globally amongst the most isolated island groups. AMD on 14 island beaches in five atolls were surveyed in 2019 using two techniques: Marine Debris Tracker (MDT) along littoral vegetation and photoquadrats in open beach. Over 60 % of AMD in both beach zones was composed of plastics, especially bottles and fragments (mean = 44.9 %, 27.2 %, range = 16.5-73.2 %, 4.8-55.9 % respectively in vegetation; mean = 28.7 %, 31.5 %, range = 17.7-40.7 %, 11.6-60.0 % respectively in open beach). The density of plastic debris in littoral vegetation (MDT data: 1995 bottles, 3328 fragments per 100 m2) was 10-fold greater than in open beach (photoquadrat data: 184 bottles, 106 fragments per 100 m2). Significant latitudinal variation in vegetation AMD occurred (8-fold greater in southern atolls, p = 0.006). AMD varied within island zones: most debris observed on oceanside beaches (oceanside vs lagoon, W = 365, p < 0.001; ocean vs island tip, W = 107, p = 0.034). Standardisation of surveys using the open-source MDT App is recommended. Debris accumulation hotspots overlapped with sea turtle nesting habitat, guiding future beach clean-up prioritisation.

A systematic review of droplet and aerosol generation in dentistry.

OBJECTIVES: This review aimed to identify which dental procedures generate droplets and aerosols with subsequent contamination, and for these, characterise their pattern, spread and settle. DATA RESOURCES: Medline(OVID), Embase(OVID), Cochrane Central Register of Controlled Trials, Scopus, Web of Science and LILACS databases were searched for eligible studies from each database's inception to May 2020 (search updated 11/08/20). Studies investigating clinical dental activities that generate aerosol using duplicate independent screening. Data extraction by one reviewer and verified by another. Risk of bias assessed through contamination measurement tool sensitivity assessment. STUDY SELECTION: A total eighty-three studies met the inclusion criteria and covered: ultrasonic scaling (USS, n = 44), highspeed air-rotor (HSAR, n = 31); oral surgery (n = 11), slow-speed handpiece (n = 4); air-water (triple) syringe (n = 4), air-polishing (n = 4), prophylaxis (n = 2) and hand-scaling (n = 2). Although no studies investigated respiratory viruses, those on bacteria, blood-splatter and aerosol showed activities using powered devices produced greatest contamination. Contamination was found for all activities, and at the furthest points studied. The operator's torso, operator's arm and patient's body were especially affected. Heterogeneity precluded inter-study comparisons but intra-study comparisons allowed construction of a proposed hierarchy of procedure contamination risk: higher (USS, HSAR, air-water syringe, air polishing, extractions using motorised handpieces); moderate (slow-speed handpieces, prophylaxis, extractions) and lower (air-water syringe [water only] and hand scaling). CONCLUSION: Gaps in evidence, low sensitivity of measures and variable quality limit conclusions around contamination for procedures. A hierarchy of contamination from procedures is proposed for challenge/verification by future research which should consider standardised methodologies to facilitate research synthesis. CLINICAL SIGNIFICANCE: This manuscript addresses uncertainty around aerosol generating procedures (AGPs) in dentistry. Findings indicate a continuum of procedure-related aerosol generation rather than the common binary AGP or non-AGP perspective. The findings inform discussion around AGPs and direct future research to support knowledge and decision making around COVID-19 and dental procedures.

Quantitative evaluation of evaporation rate during spin-coating of polymer blend films: Control of film structure through defined-atmosphere solvent-casting.

Thin films of polymer mixtures made by spin-coating can phase separate in two ways: by forming lateral domains, or by separating into distinct layers. The latter situation (self-stratification or vertical phase separation) could be advantageous in a number of practical applications, such as polymer optoelectronics. We demonstrate that, by controlling the evaporation rate during the spin-coating process, we can obtain either self-stratification or lateral phase separation in the same system, and we relate this to a previously hypothesised mechanism for phase separation during spin-coating in thin films, according to which a transient wetting layer breaks up due to a Marangoni-type instability driven by a concentration gradient of solvent within the drying film. Our results show that rapid evaporation leads to a laterally phase-separated structure, while reducing the evaporation rate suppresses the interfacial instability and leads to a self-stratified final film.

Long-term angiographic and histological results of a new hydrogel-containing filling coil in experimental rabbit aneurysms.

BACKGROUND: The aim of this study was to compare the performance of a new filling coil, the HydroFill device, to historical results of HydroSoft and bare platinum coil devices in experimental rabbit aneurysms. METHODS: Experimental aneurysms were constructed in rabbits and embolized with HydroFill (n=32), HydroSoft (n=48), or bare platinum coil (n=47) devices. Angiographic occlusion was evaluated post-treatment and at 1 month (n=55), 3 month (n=20), 6 month (n=35), and 12 month (n=12) follow-ups according to the Raymond scale. The aneurysms were analyzed histologically for neointima formation, thrombus organization, and inflammation. Continuous and discrete results were compared using ANOVA/t-test and chi (2) tests, respectively. RESULTS: Volumetric occlusion of the aneurysm sac was increased in the HydroFill group compared to the HydroSoft and platinum coil groups. Protrusions into the parent artery were common in all treatment groups due to the treatment of wide-necked aneurysms without the use of balloons or stents. Although angiographic occlusion post-treatment scores were reduced in the HydroFill group compared to the HydroSoft and platinum coil groups, stable/progressive occlusion was increased in the HydroFill group compared to the platinum coil group. Histologically, neointima formation and thrombus organization scores were increased in the HydroFill and HydroSoft groups compared to the platinum coil group at 3 months. Although there were some differences in the scoring, inflammation was generally minimal to mild in all three groups. CONCLUSION: The HydroFill device, with its high levels of volumetric filling, increased stable/progressive occlusion at follow-up, increased neointima formation, and increased thrombus organization, shows promise for clinical use.

Elucidating the fundamental fibrotic processes driving abdominal adhesion formation.

Adhesions are fibrotic scars that form between abdominal organs following surgery or infection, and may cause bowel obstruction, chronic pain, or infertility. Our understanding of adhesion biology is limited, which explains the paucity of anti-adhesion treatments. Here we present a systematic analysis of mouse and human adhesion tissues. First, we show that adhesions derive primarily from the visceral peritoneum, consistent with our clinical experience that adhesions form primarily following laparotomy rather than laparoscopy. Second, adhesions are formed by poly-clonal proliferating tissue-resident fibroblasts. Third, using single cell RNA-sequencing, we identify heterogeneity among adhesion fibroblasts, which is more pronounced at early timepoints. Fourth, JUN promotes adhesion formation and results in upregulation of PDGFRA expression. With JUN suppression, adhesion formation is diminished. Our findings support JUN as a therapeutic target to prevent adhesions. An anti-JUN therapy that could be applied intra-operatively to prevent adhesion formation could dramatically improve the lives of surgical patients.

A randomised pilot Phase II study of doxorubicin and cyclophosphamide (AC) or epirubicin and cyclophosphamide (EC) given 2 weekly with pegfilgrastim (accelerated) vs 3 weekly (standard) for women with early breast cancer.

Accelerated (dose-dense) chemotherapy, in which the frequency of administration is increased without changing total dose or duration, may increase the efficacy of cancer chemotherapy. We performed a randomised Phase II study to assess the safety and relative toxicity of AC (doxorubicin; cyclophosphamide) vs E(epirubicin)C given by conventional or accelerated schedules as neoadjuvant or adjuvant chemotherapy for early breast cancer. Furthermore, the relative toxicity of doxorubicin and epirubicin remains uncertain. Patients were randomised to one of four arms; four courses of standard 3 weekly cyclophosphamide 600 mg m(-2) in combination with doxorubicin 60 mg m(-2) (AC) vs epirubicin 90 mg m(-2) (EC) 3 weekly vs the same regimens administered every 2 weeks with pegfilgrastim (G-CSF). A total of 126 patients were treated, 42 with standard AC, 42 with accelerated AC, 19 with standard EC and 23 with accelerated EC. Significantly more grade 3/4 day one neutropenia was seen with standard (6/61, 10%) compared to accelerated (0/65,) regimens (P=0.01). A trend towards more neutropenic sepsis was seen in the combined standard and accelerated AC arms (12/84, 14%) compared to the combined EC arms (1/42, 2%), P=0.06. Falls in left ventricular ejection fraction were not increased with accelerated treatment. Accelerated AC and EC with pegfilgrastim are safe and feasible regimens in the treatment of early breast cancer with less neutropenia than conventional 3 weekly schedules.

Skeletal Stem Cell-Schwann Cell Circuitry in Mandibular Repair.

Regenerative paradigms exhibit nerve dependency, including regeneration of the mouse digit tip and salamander limb. Denervation impairs regeneration and produces morphological aberrancy in these contexts, but the direct effect of innervation on the stem and progenitor cells enacting these processes is unknown. We devised a model to examine nerve dependency of the mouse skeletal stem cell (mSSC), the progenitor responsible for skeletal development and repair. We show that after inferior alveolar denervation, mandibular bone repair is compromised because of functional defects in mSSCs. We present mSSC reliance on paracrine factors secreted by Schwann cells as the underlying mechanism, with partial rescue of the denervated phenotype by Schwann cell transplantation and by Schwann-derived growth factors. This work sheds light on the nerve dependency of mSSCs and has implications for clinical treatment of mandibular defects.

Radiotherapy-induced xerostomia: a randomised, double-blind, controlled trial of Visco-ease™ oral spray compared with placebo in patients with cancer of the head and neck.

Radiotherapy-induced xerostomia (RIX) is a common and untreatable side effect of radiotherapy to the head and neck. Visco-ease™ mouth spray (Lamellar Biomedical Ltd), a new product that is made from lamellar body mimetics, reduces the viscosity of saliva ex vivo. The purpose of this study was to evaluate its safety and effectiveness in the treatment of RIX in 43 patients with cancer of the head and neck. They were randomised into the Visco-ease™ or placebo groups, and asked to complete the Groningen radiotherapy-induced xerostomia (GRIX) questionnaire each week. The primary endpoint was a change in GRIX score from baseline to end of treatment. There was no difference in scores between the two groups, and none of the patients had device-related serious adverse events. Visco-ease™ oral spray was safe and tolerable but no better than placebo in reducing RIX in this group of patients.

Development of improved SNAP25 endopeptidase immuno-assays for botulinum type A and E toxins.

Botulinum neurotoxins contain proteases that cleave specific intra-neural proteins essential for neurotransmitter release. Toxin types A, E and C1 intra-cellularly cleave SNAP25 resulting in a flaccid paralysis. As a consequence, various different endopeptidase assays have been developed to specifically detect the toxins enzymatic activity, however, many of these suffer from variability, low sensitivity or unwanted interference exerted by product specific excipients. The current studies utilised solid phase synthesized SNAP25(137-206) peptide substrate, and specific antibody to either the SNAP25(190-197) or (173-180) octapeptide epitopes that become exposed following cleavage by toxin types A or E respectively. Assay sensitivity was increased 50 fold by the use of an optimal 0.5% Tween 20 concentration in tandem to 0.1% albumin together with an improved, simplified assay design without a pre-activation / reduction step. Sensitivities capable of detecting 0.01 LD50/ml (40fg/ml or 0.3fM) of type A toxin was achieved with a linear dose response between 0.1 and 1 LD50/ml. This provides sufficient sensitivity and precision (inter assay GCV of < 2%) for monitoring activity within any current or newly marketed therapeutic products containing less units per vial and may also make it applicable for other applications. Both purified haemagglutinin free and complexed toxins could be detected equally. Unlike type A, type E activity could unexpectedly be detected in the complete absence of reducing conditions and the optimal assay had a limit of detection of 0.2LD50/ml (4.8pg/ml) with a linear dose response between 1 and 10LD50/ml. The principle of using a detecting antibody to a substrate sequence buried within the native substrates alpha-helix may be further expanded to other specific enzyme cleavage reactions in the future.