Northern Ireland farm-level management factors for recurrent bovine tuberculosis herd breakdowns.

Bovine tuberculosis (bTB) is a chronic, infectious and zoonotic disease of domestic and wild animals caused mainly by Mycobacterium bovis. This study investigated farm management factors associated with recurrent bTB herd breakdowns (n = 2935) disclosed in the period 23 May 2016 to 21 May 2018 and is a follow-up to our 2020 paper which looked at long duration bTB herd breakdowns. A case control study design was used to construct an explanatory set of farm-level management factors associated with recurrent bTB herd breakdowns. In Northern Ireland, a Department of Agriculture Environment and Rural Affairs (DAERA) Veterinarian investigates bTB herd breakdowns using standardised guidelines to allocate a disease source. In this study, source was strongly linked to carryover of infection, suggesting that the diagnostic tests had failed to clear herd infection during the breakdown period. Other results from this study associated with recurrent bTB herd breakdowns were herd size and type (dairy herds 43% of cases), with both these variables intrinsically linked. Other associated risk factors were time of application of slurry, badger access to silage clamps, badger setts in the locality, cattle grazing silage fields immediately post-harvest, number of parcels of land the farmer associated with bTB, number of land parcels used for grazing and region of the country.

Effect of selective removal of badgers (Meles meles) on ranging behaviour during a 'Test and Vaccinate or Remove' intervention in Northern Ireland.

The role of the Eurasian badger (Meles meles) as a wildlife host has complicated the management of bovine tuberculosis (bTB) in cattle. Badger ranging behaviour has previously been found to be altered by culling of badgers and has been suggested to increase the transmission of bTB either among badgers or between badgers and cattle. In 2014, a five-year bTB intervention research project in a 100 km2 area in Northern Ireland was initiated involving selective removal of dual path platform (DPP) VetTB (immunoassay) test positive badgers and vaccination followed by release of DPP test negative badgers ('Test and Vaccinate or Remove'). Home range sizes, based on position data obtained from global positioning system collared badgers, were compared between the first year of the project, where no DPP test positive badgers were removed, and follow-up years 2-4 when DPP test positive badgers were removed. A total of 105 individual badgers were followed over 21 200 collar tracking nights. Using multivariable analyses, neither annual nor monthly home ranges differed significantly in size between years, suggesting they were not significantly altered by the bTB intervention that was applied in the study area.

Northern Ireland farm-level management factors for prolonged bovine tuberculosis herd breakdowns.

This study determined farm management factors associated with long-duration bovine tuberculosis (bTB) breakdowns disclosed in the period 23 May 2016 to 21 May 2018; a study area not previously subject to investigation in Northern Ireland. A farm-level epidemiological investigation (n = 2935) was completed when one or more Single Intradermal Comparative Cervical Test (SICCT) reactors or when one or more confirmed (positive histological and/or bacteriological result) lesion at routine slaughter were disclosed. A case-control study design was used to construct an explanatory set of management factors associated with long-duration bTB herd breakdowns; with a case (n = 191) defined as an investigation into a breakdown of 365 days or longer. Purchase of infected animal(s) had the strongest association as the most likely source of infection for long-duration bTB herd breakdowns followed by badgers and then cattle-to-cattle contiguous herd spread. However, 73.5% (95% CI 61.1-85.9%) of the herd type contributing to the purchase of infection source were defined as beef fattening herds. This result demonstrates two subpopulations of prolonged bTB breakdowns, the first being beef fattening herds with main source continuous purchase of infected animals and a second group of primary production herds (dairy, beef cows and mixed) with risk from multiple sources.

Test characteristics of the tuberculin skin test and post-mortem examination for bovine tuberculosis diagnosis in cattle in Northern Ireland estimated by Bayesian latent class analysis with adjustments for covariates.

The single intradermal comparative cervical tuberculin (SICCT) test and post-mortem examination are the main diagnostic tools for bovine tuberculosis (bTB) in cattle in the British Isles. Latent class modelling is often used to estimate the bTB test characteristics due to the absence of a gold standard. However, the reported sensitivity of especially the SICCT test has shown a lot of variation. We applied both the Hui-Walter latent class model under the Bayesian framework and the Bayesian model specified at the animal level, including various risk factors as predictors, to estimate the SICCT test and post-mortem test characteristics. Data were collected from all cattle slaughtered in abattoirs in Northern Ireland in 2015. Both models showed comparable posterior median estimation for the sensitivity of the SICCT test (88.61% and 90.56%, respectively) using standard interpretation and for post-mortem examination (53.65% and 53.79%, respectively). Both models showed almost identical posterior median estimates for the specificity (99.99% vs. 99.80% for SICCT test at standard interpretation and 99.66% vs. 99.86% for post-mortem examination). The animal-level model showed slightly narrower posterior 95% credible intervals. Notably, this study was carried out in slaughtered cattle which may not be representative for the general cattle population.

Randomized phase 2 trial of pemetrexed, pemetrexed/bevacizumab, and pemetrexed/carboplatin/bevacizumab in patients with stage IIIB/IV non-small cell lung cancer and an Eastern Cooperative Oncology Group performance status of 2.

BACKGROUND: The best treatment for patients with advanced non-small cell lung cancer (NSCLC) and a poor performance status is not well defined. In this phase 2 trial, patients were randomized to receive treatment with either single-agent pemetrexed or 1 of 2 combination regimens. METHODS: Patients with newly diagnosed, histologically confirmed nonsquamous NSCLC and an Eastern Cooperative Oncology Group (ECOG) performance status of 2 were stratified by age and serum albumin level and were randomized (1:1:1) to 1 of 3 regimens: pemetrexed (arm 1), pemetrexed and bevacizumab (arm 2), or pemetrexed, carboplatin, and bevacizumab (arm 3). The response to treatment was assessed every 2 cycles; responding and stable patients continued treatment until progression or unacceptable toxicity. RESULTS: One hundred seventy-two patients were randomized, 162 patients began the study treatment, and 146 patients completed 2 cycles and were evaluated for their response. The median progression-free survival (PFS) was 2.8 months in arm 1, 4.0 months in arm 2, and 4.8 months in arm 3. The overall response rates were 15% in arm 1, 31% in arm 2, and 44% in arm 3. The overall survival was similar in the 3 treatment arms. All 3 regimens were relatively well tolerated. Patients receiving bevacizumab had an increased incidence of hypertension, proteinuria, and bleeding episodes, but most events were mild or moderate. CONCLUSIONS: All 3 regimens were feasible for patients with advanced NSCLC and an ECOG performance status of 2. The addition of bevacizumab to pemetrexed increased the overall response rate. The efficacy of pemetrexed/carboplatin/bevacizumab (median PFS, 4.8 months) approached the prespecified study PFS goal of 5 months. Larger studies will be necessary to define the role of bevacizumab in addition to standard pemetrexed and carboplatin in this population. Cancer 2018;124:1982-91. © 2018 American Cancer Society.

The impact of the number of tuberculin skin test reactors and infection confirmation on the risk of future bovine tuberculosis incidents; a Northern Ireland perspective.

Currently policies enabling cattle herds to regain Official Tuberculosis Free (OTF) status after a bovine tuberculosis (bTB) herd incident vary between individual parts of the British Isles from requiring only one negative single comparative intradermal tuberculin test (SCITT) herd test when bTB infection is not confirmed to needing two consecutively negative SCITT herd tests after disclosure of two or more reactors, irrespective of bTB confirmation. This study used Kaplan-Meier curves and univariable and multivariable Cox Proportional Hazard models to evaluate the effect of the number of SCITT reactors and bTB confirmation on the risk of future bTB herd incident utilising data extracted from the national animal health database in Northern Ireland. Based on multivariable analyses the risk of a future bTB herd incident was positively associated with the number of SCITT reactors identified during the incident period (hazard ratio = 1.861 in incidents >5 SCITT reactors compared to incidents with only one SCITT reactor; P < 0.001), but not with bTB confirmation. These findings suggest that the probability of residual bTB infection in a herd increases with an increasing number of SCITT reactors disclosed during a bTB herd incident. It was concluded that bTB herd incidents with multiple SCITT reactors should be subjected to stricter control measures irrespective of bTB infection confirmation status.

Key actors in driving behavioural change in relation to on-farm biosecurity; a Northern Ireland perspective.

BACKGROUND: Agriculture and farming are valued contributors to local economy in Northern Ireland (NI). There is limited knowledge about farmers' behaviours and attitudes towards disease biosecurity measures. As part of a larger project, a scenario-based workshop with key stakeholders was organised by the Agri-Food and Biosciences Institute (AFBI)-NI in December 2015. RESULTS: A total of 22 participants belonging to 12 different institutions took part in the workshop. Participants were presented with an overview of previously conducted biosecurity research in NI and England. In small groups, participants were subsequently asked to discuss and give their opinions about a series of questions across four key areas in a semi-structured approach with an external facilitator. The key areas were 1- disease risk perception at the farm level; 2-perceived barriers to implementing on farm biosecurity measures; 3- avenues to successful behaviour change and 4-key industry responsibilities and roles. The discussion showed that training in biosecurity for farmers is important and necessary. Training was recommended to be provided by veterinary surgeons, preferably via a face-to-face format. The discussion addressing disease disclosure proved particularly challenging between those who were prospective buyers of cattle, and those who sold cattle. CONCLUSIONS: This workshop provided a unique and invaluable insight into key issues regarding farm level biosecurity activities. From a policy perspective, delivering improved on-farm biosecurity must be addressed via a multidisciplinary approach. This can only be achieved with active involvement, commitment and support of a number of key industry and government stakeholders.

Bovine tuberculosis in Northern Ireland: quantification of the population disease-level effect from cattle leaving herds detected as a source of infection.

Determination of the proportion of bovine tuberculosis (bTB) breakdowns attributed to a herd purchasing infected animals has not been previously quantified using data from the Animal and Public Health Information System (APHIS) database in Northern Ireland. We used a case-control study design to account for the infection process occurring in the disclosing bTB breakdown herds. Cases (N = 6926) were cattle moving to a future confirmed bTB breakdown where they would disclose as a confirmed bTB reactor or a Lesion at Routine Slaughter (LRS). Controls (N = 303 499) were cattle moving to a future confirmed bTB breakdown where they did not become a bTB reactor or LRS. Our study showed that the cattle leaving herds which disclosed bTB within 450 days had an increased odds of becoming a confirmed bTB reactor or LRS compared with the cattle which left herds that remained free for 450 days (odds ratio (OR) = 2·09: 95% CI 1·96-2·22). Of the 12 060 confirmed bTB breakdowns included in our study (2007-2015 inclusive), 31% (95% CI 29·8-31·5) contained a confirmed bTB reactor(s) or LRS(s) at the disclosing test which entered the herd within the previous 450 days. After controlling for the infection process occurring in the disclosing bTB breakdown herd, our study showed that 6·4% (95% CI 5·9-6·8) of bTB breakdowns in Northern Ireland were directly attributable to the movement of infected animals.

Increased use of cadaver specimens as a method for improving medical student satisfaction with clinical ear anatomy teaching at St George's, University of London: a pilot study.

BACKGROUND: Delivering sufficient otology education for undergraduates is known to be difficult, with limited teaching time being a contributing factor. Increasing student access to dissections of the ear could serve to increase satisfaction with teaching at St George's, University of London, UK. OBJECTIVE: To evaluate student satisfaction with clinical ear anatomy teaching and investigate whether it can be improved using dissected specimens. METHOD: Participants completed an online survey and knowledge examinations, both before and after attending a new tutorial, with answers from before and after the session being compared. RESULTS: Pre-teaching satisfaction scores concerning teaching were low, at an average of 2.45 (out of 7), with a mean examination result of 6.53 (out of 10). Post-teaching average satisfaction increased by 3.20 points to 5.65 (out of 7) (p < 0.01) and examination scores increased by 1.53 points to 8.07 (out of 10) (p < 0.01). CONCLUSION: Students are supportive of increased access to cadaver dissections of the ear, and facilitating this can improve satisfaction with otology teaching.

Dead-reckoning elucidates fine-scale habitat use by European badgers Meles meles.

Background: Recent developments in both hardware and software of animal-borne data loggers now enable large amounts of data to be collected on both animal movement and behaviour. In particular, the combined use of tri-axial accelerometers, tri-axial magnetometers and GPS loggers enables animal tracks to be elucidated using a procedure of 'dead-reckoning'. Although this approach was first suggested 30 years ago by Wilson et al. (1991), surprisingly few measurements have been made in free-ranging terrestrial animals. The current study examines movements, interactions with habitat features, and home-ranges calculated from just GPS data and also from dead-reckoned data in a model terrestrial mammal, the European badger (Meles meles). Methods: Research was undertaken in farmland in Northern Ireland. Two badgers (one male, one female) were live-trapped and fitted with a GPS logger, a tri-axial accelerometer, and a tri-axial magnetometer. Thereafter, the badgers' movement paths over 2 weeks were elucidated using just GPS data and GPS-enabled dead-reckoned data, respectively. Results: Badgers travelled further using data from dead-reckoned calculations than using the data from only GPS data. Whilst once-hourly GPS data could only be represented by straight-line movements between sequential points, the sub-second resolution dead-reckoned tracks were more tortuous. Although there were no differences in Minimum Convex Polygon determinations between GPS- and dead-reckoned data, Kernel Utilisation Distribution determinations of home-range size were larger using the former method. This was because dead-reckoned data more accurately described the particular parts of landscape constituting most-visited core areas, effectively narrowing the calculation of habitat use. Finally, the dead-reckoned data showed badgers spent more time near to field margins and hedges than simple GPS data would suggest. Conclusion: Significant differences emerge when analyses of habitat use and movements are compared between calculations made using just GPS data or GPS-enabled dead-reckoned data. In particular, use of dead-reckoned data showed that animals moved 2.2 times farther, had better-defined use of the habitat (revealing clear core areas), and made more use of certain habitats (field margins, hedges). Use of dead-reckoning to provide detailed accounts of animal movement and highlight the minutiae of interactions with the environment should be considered an important technique in the ecologist's toolkit.

Excitable patterns in active nematics.

We analyze a model of mutually propelled filaments suspended in a two-dimensional solvent. The system undergoes a mean-field isotropic-nematic transition for large enough filament concentrations, and the nematic order parameter is allowed to vary in space and time. We show that the interplay between nonuniform nematic order, activity, and flow results in spatially modulated relaxation oscillations, similar to those seen in excitable media. In this regime the dynamics consists of nearly stationary periods separated by "bursts" of activity in which the system is elastically distorted and solvent is pumped throughout. At even higher activity, the dynamics becomes chaotic.

The African Programme for Onchocerciasis Control: impact on onchocercal skin disease.

OBJECTIVES: To assess the long-term impact of the African Programme for Onchocerciasis Control on itching and onchocercal skin disease (OSD). METHODS: Seven study sites in Cameroon, Sudan, Nigeria and Uganda participated. Two cross-sectional surveys were conducted of communities meso- and hyper-endemic for onchocerciasis before and after 5 or 6 years of community-directed treatment with ivermectin (CDTI). Individuals were asked about any general health symptoms including itching and underwent full cutaneous examinations. Onchocercal skin lesions were documented according to a standard classification. RESULTS: Five thousand one hundred and ninety three people were examined in phase I and 5,180 people in phase II. The presence of onchocercal nodules was a strongly significant (P < 0·001) risk factor for all forms of onchocercal skin disease: APOD (OR 1·66); CPOD (OR 2·84); LOD (OR 2·68); reactive skin lesions (OR 2·38) and depigmentation (OR 3·36). The effect of community-directed treatment with ivermectin was profound. At phase II, there were significant (P < 0·001) reductions in the odds of itching (OR 0·32), APOD (OR 0·28); CPOD (OR 0·34); reactive skin lesions (OR 0·33); depigmentation (OR 0·31) and nodules (OR 0·37). Reduction in the odds of LOD was also significant (OR 0.54, P < 0.03). CONCLUSIONS: This first multi-country report of the long-term impact of CDTI reveals a substantial reduction in itching and OSD. APOC operations are having a major effect in improving skin health in poor rural populations in Africa.

Are major roads effective barriers for badger (Meles meles) movements?

As part of a bovine tuberculosis (bTB) control related Test and Vaccinate or Remove (TVR) badger research study in Northern Ireland, a project was launched evaluating whether badgers cross major roads (in this case the A1 dual carriageway linking Belfast/Newry/Dublin). This road formed the western boundary of the TVR study area and it was chosen to discourage badger movements in and out of the area. This was important in order to ensure that the badger study population was as stable as possible and also to get a better understanding of the risk of any spill over of bTB infection from the study area to the buffer area. Five badgers trapped close to the A1 were fitted with a Global Positioning System (GPS) collar in October 2017, which were set to record the badger location every 20 min between 19.20 and 03.00 h during a maximum of 84 days. Based on 4313 location points recorded, only 2 (0.05%) location points were located on the western side of the A1. Although this was a small sample, it can be concluded that generally badgers avoid crossing dual carriageways which is supported by evidence from other studies. This finding is important for informing on development of future badger intervention areas where major roads could be considered as strong borders. Furthermore, it adds to the body of knowledge in trying to understand drivers and barriers for badger dispersal behaviour.

Physiology: does gut hormone PYY3-36 decrease food intake in rodents?

Batterham et al. report that the gut peptide hormone PYY3-36 decreases food intake and body-weight gain in rodents, a discovery that has been heralded as potentially offering a new therapy for obesity. However, we have been unable to replicate their results. Although the reasons for this discrepancy remain undetermined, an effective anti-obesity drug ultimately must produce its effects across a range of situations. The fact that the findings of Batterham et al. cannot easily be replicated calls into question the potential value of an anti-obesity approach that is based on administration of PYY3-36.

Input vector optimization of feed-forward neural networks for fitting ab initio potential-energy databases.

The variation in the fitting accuracy of neural networks (NNs) when used to fit databases comprising potential energies obtained from ab initio electronic structure calculations is investigated as a function of the number and nature of the elements employed in the input vector to the NN. Ab initio databases for H(2)O(2), HONO, Si(5), and H(2)C[Double Bond]CHBr were employed in the investigations. These systems were chosen so as to include four-, five-, and six-body systems containing first, second, third, and fourth row elements with a wide variety of chemical bonding and whose conformations cover a wide range of structures that occur under high-energy machining conditions and in chemical reactions involving cis-trans isomerizations, six different types of two-center bond ruptures, and two different three-center dissociation reactions. The ab initio databases for these systems were obtained using density functional theory/B3LYP, MP2, and MP4 methods with extended basis sets. A total of 31 input vectors were investigated. In each case, the elements of the input vector were chosen from interatomic distances, inverse powers of the interatomic distance, three-body angles, and dihedral angles. Both redundant and nonredundant input vectors were investigated. The results show that among all the input vectors investigated, the set employed in the Z-matrix specification of the molecular configurations in the electronic structure calculations gave the lowest NN fitting accuracy for both Si(5) and vinyl bromide. The underlying reason for this result appears to be the discontinuity present in the dihedral angle for planar geometries. The use of trigometric functions of the angles as input elements produced significantly improved fitting accuracy as this choice eliminates the discontinuity. The most accurate fitting was obtained when the elements of the input vector were taken to have the form R(ij) (-n), where the R(ij) are the interatomic distances. When the Levenberg-Marquardt procedure was modified to permit error minimization with respect to n as well as the weights and biases of the NN, the optimum powers were all found to lie in the range of 1.625-2.38 for the four systems studied. No statistically significant increase in fitting accuracy was achieved for vinyl bromide when a different value of n was employed and optimized for each bond type. The rate of change in the fitting error with n is found to be very small when n is near its optimum value. Consequently, good fitting accuracy can be achieved by employing a value of n in the middle of the above range. The use of interparticle distances as elements of the input vector rather than the Z-matrix variables employed in the electronic structure calculations is found to reduce the rms fitting errors by factors of 8.86 and 1.67 for Si(5) and vinyl bromide, respectively. If the interparticle distances are replaced with input elements of the form R(ij) (-n) with n optimized, further reductions in the rms error by a factor of 1.31 to 2.83 for the four systems investigated are obtained. A major advantage of using this procedure to increase NN fitting accuracy rather than increasing the number of neurons or the size of the database is that the required increase in computational effort is very small.

Prevalence and distribution of ocular onchocerciasis in three ecological zones in Nigeria.

The African Programme for Onchocerciasis Control (APOC) sponsored a baseline study in Nigeria between 1998 and 1999 on the prevalence and distribution of Onchocerciasis. The randomly selected 1,064 subjects in the baseline study underwent detailed eye examination in Cross River (rain forest), Taraba (savanna) and Kogi (forest-savanna) States. This paper compares and contrasts the public health significance of ocular onchocerciasis in these ecological zones. A blindness prevalence of 2.4% was recorded in the study, onchocerciasis being responsible for 30.2% of the bilaterally blind subjects. Onchocerciasis-induced blindness prevalence was relatively high in the rain forest and forest savanna zones of Cross River and Kogi States, Cross River having the highest site-specific prevalence (50.0%), followed by Kogi (41.7%). Taraba recorded only 27.3%. Other conditions identified included glaucoma, optic nerve disease and cataract rates of which were also found to be high among the population (6.9%, 6.5 % and 8.9% respectively). Anterior segment onchocercal lesions, punctate and sclerosing keratitis were the predominant features of the infection in the savanna zone (14.1% and 6.3% respectively), while posterior segment lesions were much more common in the forest zone. The need to sustain the present efforts to control onchocerciasis through mass ivermectin treatment is recommended.

Evaluating the application of the dual path platform VetTB test for badgers (Meles meles) in the test and vaccinate or remove (TVR) wildlife research intervention project in Northern Ireland.

European badgers (Meles meles) are accepted as a wildlife reservoir host for Mycobacterium bovis, which causes bovine tuberculosis (bTB) in the British Isles. The objective of this study was to evaluate the use of Dual Path Platform (DPP) VetTB test (Chembio Diagnostic Systems Inc., Medford, NY, USA) within a Test and Vaccinate or Remove (TVR) wildlife research intervention project. Blood samples were collected from 456 individual badgers, trapped in 2015 and 2016, and tested in the field with DPP VetTB test using whole blood. Additionally, whole blood and serum samples were taken to the laboratory for further DPP VetTB testing and for gamma interferon (IFN-γ) testing. Swabs were taken from the oropharynx and trachea and submitted for bacteriological culture as were swabs from wounds, if present. Field DPP VetTB test positive badgers were euthanised and underwent post-mortem examination and bTB confirmatory testing. The results demonstrated that the test performed as well in the field using whole blood as DPP Vet TB tests in the laboratory using sera or whole blood, and as well as other established tests for M. bovis. Visual assessment of the DPP VetTB test using serum under laboratory conditions showed a high degree of consistency between raters. Using a relative gold standard (parallel interpretation of IFN-γ assay and oropharyngeal/tracheal sample/culture), sensitivity estimates for the DPP VetTB test using sera and whole blood were 0.5 (95%CI 0.34-0.66) and 0.42 (95%CI 0.24-0.66), respectively. Specificity estimates were 0.95 (95%CI 0.93-0.97) for sera and 0.89 (95%CI 0.86-0.92) for whole blood. Parallel interpretation of Band 1 (MPB83) and Band 2 (CFP-10/ESAT-6) of the DPP VetTB test was not superior to interpretation of Band 1 only. The results give confidence in the reliability and reproducibility of the DPP VetTB test for badgers under field conditions and therefore it is considered appropriate for use in a badger bTB control campaign.

A comparison of HDR brachytherapy and IMRT techniques for dose escalation in prostate cancer: a radiobiological modeling study.

A course of one to three large fractions of high dose rate (HDR) interstitial brachytherapy is an attractive alternative to intensity modulated radiation therapy (IMRT) for delivering boost doses to the prostate in combination with additional external beam irradiation for intermediate risk disease. The purpose of this work is to quantitatively compare single-fraction HDR boosts to biologically equivalent fractionated IMRT boosts, assuming idealized image guided delivery (igIMRT) and conventional delivery (cIMRT). For nine prostate patients, both seven-field IMRT and HDR boosts were planned. The linear-quadratic model was used to compute biologically equivalent dose prescriptions. The cIMRT plan was evaluated as a static plan and with simulated random and setup errors. The authors conclude that HDR delivery produces a therapeutic ratio which is significantly better than the conventional IMRT and comparable to or better than the igIMRT delivery. For the HDR, the rectal gBEUD analysis is strongly influenced by high dose DVH tails. A saturation BED, beyond which no further injury can occur, must be assumed. Modeling of organ motion uncertainties yields mean outcomes similar to static plan outcomes.

A self-starting method for obtaining analytic potential-energy surfaces from ab initio electronic structure calculations.

Previous methods proposed for obtaining analytic potential-energy surfaces (PES) from ab initio electronic structure calculations are not self-starting. They generally require that the sampling of configuration space important in the reaction dynamics of the process being investigated be initiated by using chemical intuition or a previously developed semiempirical potential-energy surface. When the system under investigation contains four or more atoms undergoing three- and four-center reactions in addition to bond scission processes, obtaining a sufficiently converged initial sampling can be very difficult due to the extremely large volume of configuration space that is important in the reaction dynamics. It is shown that by combining direct dynamics (DD) with previously reported molecular dynamics (MD), novelty sampling (NS), and neural network (NN) methods, an analytical surface suitable for MD computations for large systems may be obtained. Application of the method to the investigation of N-O bond scission and cis-trans isomerization reactions of HONO followed by comparison of the resulting neural network potential-energy surface to one obtained by using a semiempirical potential to initiate the sampling shows that the two potential surfaces are the same within the fitting accuracy of the surfaces. It is concluded that the combination of direct dynamics, molecular dynamics, novelty sampling, and neural network fitting provides a self-starting, robust, and accurate DD/MD/NS/NN method for the execution of first-principles, ab initio, molecular dynamics studies in systems containing four or more atoms which are undergoing simultaneous two-, three-, and four-center reactions.