Progressing Antimicrobial Resistance Sensing Technologies across Human, Animal, and Environmental Health Domains

The spread of antimicrobial resistance (AMR) is a rapidly growing threat to humankind on both regional and global scales. As countries worldwide prepare to embrace a One Health approach to AMR management, which is one that recognizes the interconnectivity between human, animal, and environmental health, increasing attention is being paid to identifying and monitoring key contributing factors and critical control points. Presently, AMR sensing technologies have significantly progressed phenotypic antimicrobial susceptibility testing (AST) and genotypic antimicrobial resistance gene (ARG) detection in human healthcare. For effective AMR management, an evolution of innovative sensing technologies is needed for tackling the unique challenges of interconnected AMR across various and different health domains. This review comprehensively discusses the modern state-of-play for innovative commercial and emerging AMR sensing technologies, including sequencing, microfluidic, and miniaturized point-of-need platforms. With a unique view toward the future of One Health, we also provide our perspectives and outlook on the constantly changing landscape of AMR sensing technologies beyond the human health domain.

Refrigeration and freezing of porcine tissue does not affect the retardation of fragment simulating projectiles

Explosively propelled fragments are the most common cause of injury to UK service personnel in modern conflicts. Numerical injury models to simulate such injuries utilise algorithms based upon gelatin and animal tissue testing but data is limited on many fragment simulating projectiles and these simulants cannot represent human anatomy. Testing with post mortem specimens may overcome this limitation but no information exists about how post mortem tissue changes and storage conditions in humans or animals may affect projectile penetration. Two chisel nosed cylinders (0.49 g and 1.10 g) and a 0.51 g (5 mm) sphere were fired into three groups of porcine tissue (fresh, refrigerated and frozen then refrigerated) and compared to 20% gelatin. Depth of projectile penetration was ascertained with the assistance of computed tomography and kinetic energy absorption by tissues measured using Doppler radar and high speed photography. No difference in depth of penetration was found between porcine tissue stored in the different manners compared with 20% gelatin by impact velocities less than 100 m/s. Insufficient numbers of projectiles were retained in tissue at higher velocities for statistical analysis to be undertaken. Energy absorbed per millimetre of tissue ranged between 0.42 and 0.98 J/mm for different porcine tissue despite differing storage. This pilot study would suggest that the effect of refrigerating or freezing porcine tissue followed by thawing has no effect on its ability to retard these projectiles. Further research is required to ascertain if these results occur at greater velocities and for other types of projectile.

Bone mineral crystallisation kinetics

The kinetics of bone apatite crystallisation are examined using a novel approach to obtain quantitative, direction dependence features such as growth rate and activation energy. X-ray diffraction was employed for analysis of bovine, porcine and 'anorganic' bone specimens. Apatite coherence length was utilised as the independent variable within a Johnson-Mehl-Avrami (JMA) model. A direction averaged crystallisation activation energy of 183 ± 8 kJ mol(-1) was observed for the three bone groups. The Johnson-Mehl-Avrami 'n' exponent decreased with increasing temperature for all bone groups, indicating that apatite crystallisation changes to a diffusion limited process at higher temperatures. The results revealed little evidence to support any organic component 'protective' effect, and, on the contrary indicated that the organic matrix promotes apatite crystallisation.

High-cocoa polyphenol-rich chocolate improves HDL cholesterol in Type 2 diabetes patients

AIM

To examine the effects of chocolate on lipid profiles, weight and glycaemic control in individuals with Type 2 diabetes.

METHODS

Twelve individuals with Type 2 diabetes on stable medication were enrolled in a randomized, placebo-controlled double-blind crossover study. Subjects were randomized to 45 g chocolate with or without a high polyphenol content for 8 weeks and then crossed over after a 4-week washout period. Changes in weight, glycaemic control, lipid profile and high-sensitivity C-reactive protein were measured at the beginning and at the end of each intervention.

RESULTS

HDL cholesterol increased significantly with high polyphenol chocolate (1.16 ± 0.08 vs. 1.26 ± 0.08 mmol/l, P = 0.05) with a decrease in the total cholesterol: HDL ratio (4.4 ± 0.4 vs. 4.1 ± 0.4 mmol/l, P = 0.04). No changes were seen with the low polyphenol chocolate in any parameters. Over the course of 16 weeks of daily chocolate consumption neither weight nor glycaemic control altered from baseline.

CONCLUSION

High polyphenol chocolate is effective in improving the atherosclerotic cholesterol profile in patients with diabetes by increasing HDL cholesterol and improving the cholesterol:HDL ratio without affecting weight, inflammatory markers, insulin resistance or glycaemic control.

Using GIS to create synthetic disease outbreaks

Background

The ability to detect disease outbreaks in their early stages is a key component of efficient disease control and prevention. With the increased availability of electronic health-care data and spatio-temporal analysis techniques, there is great potential to develop algorithms to enable more effective disease surveillance. However, to ensure that the algorithms are effective they need to be evaluated. The objective of this research was to develop a transparent user-friendly method to simulate spatial-temporal disease outbreak data for outbreak detection algorithm evaluation.

A state-transition model which simulates disease outbreaks in daily time steps using specified disease-specific parameters was developed to model the spread of infectious diseases transmitted by person-to-person contact. The software was developed using the MapBasic programming language for the MapInfo Professional geographic information system environment.

Results

The simulation model developed is a generalised and flexible model which utilises the underlying distribution of the population and incorporates patterns of disease spread that can be customised to represent a range of infectious diseases and geographic locations. This model provides a means to explore the ability of outbreak detection algorithms to detect a variety of events across a large number of stochastic replications where the influence of uncertainty can be controlled. The software also allows historical data which is free from known outbreaks to be combined with simulated outbreak data to produce files for algorithm performance assessment.

Conclusion

This simulation model provides a flexible method to generate data which may be useful for the evaluation and comparison of outbreak detection algorithm performance.

Effects of lesioning noradrenergic neurones in the locus coeruleus on conditioned and unconditioned aversive behaviour in the rat

1. The brain noradrenergic system may have a role in anxiety disorder. This study has examined the effect of bilateral 6-hydroxydopamine lesions of the noradrenergic neurones in the locus coeruleus (LC) of male Lister hooded rats on behaviour produced by unconditioned and conditioned aversive stimuli. 2. The 6-hydroxydopamine (4 microg) lesions markedly reduced the noradrenaline content of the locus coeruleus hypothalamus, frontal cortex and the periaqueductal grey area without altering the levels of either dopamine or 5-hydroxytryptamine measured 14 days after administration. 3. Exposure to ultrasound (20 kHz at 98 dB for 60 sec), an unconditioned aversive stimulus, induced a defence response in the rats characterised by an increase in activity (running and jumping) followed by a period of inactivity (freezing). 4. Lesioning of the LC significantly attenuated the duration of freezing but was without effect on the active phase of the response. A similar reduction in freezing behaviour was seen with LC lesions when rats were exposed (3 hours after the acquisition) to the contextual cue of the conditioned emotion response paradigm. 5. These findings confirm that the locus coeruleus is involved in the regulation of fear-related behaviour in the rat both in an unconditioned and a conditioned model. Furthermore the results indicate that noradrenaline modifies defence behaviour rather than being the principle activating mechanism.

E-5842 (Laboratories Dr Esteve)

Esteve is developing E-5842, a sigma1 opioid receptor ligand, as a potential therapy for psychosis. It has completed phase I trials [344879,346244]. As of May 1999, the site and protocol for phase II schizophrenia trials in the UK had been finalized and these were scheduled to begin shortly thereafter, with results likely to be available by the end of 2000 [365516]. E-5842 acted as an atypical antipsychotic in preclinical neurochemical and behavioral tests. Both acute (40 mg/kg ip for 2 h) and chronic (20 mg/kg ip daily for 21 days) administration of E-5842 increased PLC activity and the drug may thus achieve its antipsychotic effects via a signalling pathway involving phosphoinositide second messengers [336324]. E-5842 has a K(i) value of 4 nM at the sigma receptor [306875]. It blocks apomorphine-induced climbing, and antagonizes amphetamine-induced locomotor activity in mice [271405].

Acoustically elicited behaviours in Lister hooded and Wistar rats

It has been reported previously that experimenter-presented 20-kHz tones at low intensities produce bursts of locomotor running in Lister hooded rats, but reduced locomotion (freezing) in Wistar rats. Because rats emit 20-kHz tones when stressed, it was proposed that this ultrasound-elicited running and freezing behaviour in Lister hooded and Wistar rats, respectively, represents a model for qualitative strain differences in fear behaviour. The present studies examined the acoustic specificity of acoustically elicited locomotor behaviours in Lister hooded and Wistar rats. In Experiment 1, it was found that brief exposure (i.e., 15 s) of Lister hooded rats to tones at frequencies of 7, 12, or 20 kHz and intensities of 85-95 dB SPL, elicited running behaviour characterised by brief bursts of locomotion followed by periods of quiescence. Somewhat surprisingly, the 7- and 12-kHz tones elicited running behaviour at lower intensities than did the 20-kHz tones. In Experiment 2, it was found that exposure of Lister hooded rats to the 20-kHz acoustic stimulus (91-101 dB, SPL) for a much longer duration, up to 9 min, resulted in episodic bursts of locomotion and convulsions in a significant proportion of subjects. Both the maximal velocity of locomotion and the likelihood of occurrence of convulsions was related to the intensity of the acoustic stimulus. Exposure of Lister hooded rats to white noise for up to 9 min also elicited episodic bursts of locomotion and convulsions in an intensity-dependent manner. The white noise stimulus was found to be a more effective stimulus than the 20-kHz stimulus in this regard. In Experiment 3, it was found that Lister hooded rats exhibited reduced locomotion when they were exposed to a low-intensity 20-kHz acoustic stimulus (e.g., 81 dB, SPL). In Experiment 4, it was found that Wistar rats did not exhibit locomotor bursts or convulsions when presented with 20-kHz tones using stimulus parameters equal to and even greater than those that had been shown to be effective in producing locomotor bursts in Lister hooded rats. Rather, Wistar rats exhibited only reduced locomotion. The present data indicate that (1) running behaviour in Lister hooded rats is not specific for the 20-kHz stimulus. Moreover, (2) when compared to Lister hooded rats, Wistar rats are relatively insensitive to the running and convulsions elicited by acoustic stimuli. Finally, (3) both Lister hooded and Wistar rats exhibited reduced locomotion when presented with the 20-kHz tones, although the range of stimulus intensities that produces freezing behaviour is much more limited in Lister hooded rats because of their propensity to exhibit locomotor bursting and convulsions. Thus, it appears that the difference between the two strains with respect to their unconditioned locomotor responses to novel acoustic stimuli relates to the fact that Lister hooded rats are uniquely susceptible to acoustically elicited locomotor bursts and/or convulsions.

Economic evaluation of three anthelmintic strategies for lamb flocks affected by benzimidazole-resistant nematodes

OBJECTIVE

To compare the profitability of three anthelmintic strategies in growing lambs in flocks with nematodes resistant to benzimidazole anthelmintics.

METHOD

A partial-budgeting analysis was carried out by means of a stochastic simulation model, which allows inputs to be described as distributions rather than as fixed values, and hence permits variation between farms to be considered in the analysis.

RESULTS

The results show that control of nematode parasites by use of an effective anthelmintic provides the highest net returns, yielding a margin over ineffectively treated lambs of A$114 per 100 lambs on average. Suppressive treatment based on the administration of two controlled-release capsules and monthly with moxidectin resulted in an average loss of A$131 per 100 lambs in comparison with animals treated with an ineffective anthelmintic. Analysis of the results from capsule-treated lambs did not take into account the unmeasured benefits associated with less contamination of pastures. Sensitivity analysis using a stochastic model indicates that apart from the effect of treatment on weight gain variation in carcase price greatly influences the profitability of all the parasite control programs examined.

CONCLUSION

The results suggest that it is economically important for farmers to adjust their strategy in the presence of anthelmintic resistance. But as a result of uncertainty in the factors influencing economic return, the expected economic benefit is likely to vary substantially.

A quantitative assessment of the validity of animal-health surveys using stochastic modelling

This paper presents a stochastic simulation model to evaluate the efficacy of regional or national surveys aimed at identifying infection in populations of animals. The process of evaluation involves specification or calculation of cluster-level test sensitivity and specificity, which are derived from two probability distributions of the number of individual-level positive tests expected from non-infected and infected clusters, respectively. Probability distributions for the number of positive clusters expected in a situation of freedom from infection and under various levels of cluster prevalence are specified and used to determine survey properties (the survey being considered a diagnostic system), and ROC curves are drawn. Likelihood ratios allow investigators to state the extent to which a survey result is more likely to be observed if the region or country is infected at a given prevalence than if it is free from infection. The result of a survey carried out to investigate the presence of porcine reproductive and respiratory syndrome (PRRS) in Switzerland is used to illustrate this approach. The model can be adapted to a wide range of survey designs.

Effects of monensin on the reproduction, health, and milk production of dairy cows

A randomized clinical trial including 1109 cows from 12 Australian dairy herds was used to evaluate the effects of monensin on the health (n = > 686 cows), production (n = 915 cows), and reproduction (n = > 908 cows) of dairy cows. Cows were allocated to a treatment group receiving a slow-release intraruminal bolus containing 32 g of sodium monensin that was administered 40 d before and 50 d following the anticipated calving date or to a control group. Treatment did not significantly alter any reproductive outcome; 54.5% of cows treated with monensin and 58.2% of control cows were pregnant at first service, and days to conception were lower for cows treated with monensin. The hazard rate (0.95) was not significant for these cows. The percentage of cows pregnant was 83.8 for control cows, and days to first estrus (hazard rate = 1.04) and first service (hazard rate = 1.04) were not significantly higher for treated cows. Treatment with monensin did not significantly alter the risk of any disease. The incidence of retained fetal membranes, pyometra, lameness, abortion, and infectious diseases was not significantly lower for cows in the treatment group, and the incidence of mastitis was not significantly higher for cows in the treatment group. Monensin significantly increased milk production by 0.75 L/d per cow and tended to increase milk fat and protein yields but had no significant effect on milk fat or milk protein percentages. Changes in the production of milk and milk constituents were consistent throughout lactation.

The effect of central and systemic injection of the 5-HT1A receptor agonist 8-OHDPAT and the 5-HT1A receptor antagonist WAY100635 on periaqueductal grey-induced defence behaviour

The effects of the selective 5-HT(1A) agonist, 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OHDPAT) and the selective 5-HT(1A) antagonist, N-[2-[4-(2-methoxyphenyl)-1-piperzinyl]ethyl]-N-(pyridinyl) cyclohexanecarboxamide trichloride (WAY100635) on periaqueductal grey (PAG)-stimulated defence behaviour were tested in the rat. Microinjection of the excitatory amino acid, D, L-homocysteic acid (DLH) into the dorsal region of the PAG produced overt aversive behaviour characteristic of the defence response, consisting of explosive motor behaviours which were quantified in terms of their duration and the number of arena revolutions and jumps made by the animal. Intra-PAG pre-treatment with 8-OHDPAT (3, 10 and 25 nmol in 250 nl) 10 min before DLH stimulation significantly attenuated the defence behaviour. This could be reversed by peripheral application of WAY100635 (0.1 mg/kg). In contrast, peripheral 8-OHDPAT (0.03, 0.1 and 0.3mg/kg) produced a significant potentiation of the DLH response which could also be blocked by peripheral WAY100635. When WAY100635 (10 nmol in 250 nl) alone was given into the PAG a significant increase in DLH induced behaviours was observed whereas peripherally applied WAY100635 (0.1 mg/kg) was without effect. These data support previous findings which indicate that serotonergic modulation of aversive behaviours such as defence can be mediated by 5-HT(1A) receptors. Furthermore there is evidence to indicate a differential involvement of pre- and postsynaptic 5-HT(1A) receptors.

Perinatal cocaine reduces responsiveness to cocaine and causes alterations in exploratory behavior and visual discrimination in young-adult rats

Lister hooded female rats were exposed to either saline or cocaine (20 mg/kg s.c.) from gestational day 10 every other day until weaning (postnatal day 25). The effects of maternal cocaine exposure on novelty-induced exploration and on spontaneous and cocaine-induced motor activity were evaluated in young-adult male offspring (4 weeks after weaning). Rats exposed to cocaine during development spent less time exploring two novel objects. Lack of habituation upon the second presentation of the objects and failure in the ability to discriminate between the novel and familiar object were also found in cocaine exposed offspring. Moreover, maternal cocaine treatment did not affect spontaneous motor activity (active time, average speed and rearing) in rats subjected to an open field test. Furthermore, perinatal exposure to cocaine significantly attenuated acute cocaine (15 mg/kg i.p.)-induced hyperactivity. These data indicate that developmental exposure to cocaine, at dose levels below those producing gross malformations and/or overt signs of neurotoxicity, causes behavioral changes characterized by an altered responsiveness to environmental and pharmacological challenges.

Computer analysis and quantification of periaqueductal grey-induced defence behaviour

The pharmacological study of midbrain-evoked aversive behaviours is commonly measured in terms of electrical escape thresholds, although studies which examine the actual expression of the behaviour are being introduced. A computer-driven automated tracking system has been developed to record and analyse the very rapid locomotor activity produced by the defence response. Stimulation of the midbrain periaqueductal grey (PAG) matter in rats with the excitatory amino acid D,L-homocysteic acid (DLH) produced very rapid and short-lasting escape behaviour which was tracked by computer. The system, VideoTrack, determines the speed and distance travelled by the animal and stores and statistically analyses the data. VideoTrack was able to detect a pharmacological modifications of the response; anti-aversive effects produced by intra-PAG pretreatment with the 5-HT1A agonist 8-hydroxy 2-(di-n-propylamino)tetralin (8-OHDPAT) and its reversal by peripheral pretreatment with the 5-HT1A antagonist N-[2-[-(2-methoxyphenyl)-1-piperazinyl]ethyl-N- (pyridinyl)cyclohexanecarboxanide (WAY 100635).