Wastewater-based epidemiology as a public health resource in low- and middle-income settings

In the face of emerging and re-emerging diseases, novel and innovative approaches to population scale surveillance are necessary for the early detection and quantification of pathogens. The last decade has seen the rapid development of wastewater and environmental surveillance (WES) to address public health challenges, which has led to establishment of wastewater-based epidemiology (WBE) approaches being deployed to monitor a range of health hazards. WBE exploits the fact that excretions and secretions from urine, and from the gut are discharged in wastewater, particularly sewage, such that sampling sewage systems provides an early warning system for disease outbreaks by providing an early indication of pathogen circulation. While WBE has been mainly used in locations with networked wastewater systems, here we consider its value for less connected populations typical of lower-income settings, and in assess the opportunity afforded by pit latrines to sample communities and localities. We propose that where populations struggle to access health and diagnostic facilities, and despite several additional challenges, sampling unconnected wastewater systems remains an important means to monitor the health of large populations in a relatively cost-effective manner.

Surface-Enhanced Spatially Offset Raman Spectroscopy in Tissue

One aim of personalized medicine is to use continuous or on-demand monitoring of metabolites to adjust prescription dosages in real time. Surface-enhanced spatially offset Raman spectroscopy (SESORS) is an optical technique capable of detecting surface-enhanced Raman spectroscopy (SERS)-active targets under a barrier, which may enable frequent metabolite monitoring. Here we investigate how the intensity of the signal from SERS-active material varies spatially through tissue, both experimentally and in a computational model. Implant-sized, SERS-active hydrogel was placed under different thicknesses of contiguous tissue. Emission spectra were collected at the air-tissue boundary over a range of offsets from the excitation site. New features were added to the Monte Carlo light-tissue interaction model to modify the optical properties after inelastic scattering and to calculate the distribution of photons as they exit the model. The Raman signals were detectable through all barrier thicknesses, with strongest emission for the case of 0 mm offset between the excitation and detector. A steep decline in the signal intensities occurred for offsets greater than 2 mm. These results did not match published SORS work (where targets were much larger than an implant). However, the model and experimental results agree in showing the greatest intensities at 0 mm offset and a steep gradient in the intensities with increasing offset. Also, the model showed an increase in the number of photons when the new, longer wavelengths were used following the Stokes shift for scattering and the graphical display of the exiting photons was helpful in the determination and confirmation of the optimal offset.

City-wide wastewater genomic surveillance through the successive emergence of SARS-CoV-2 Alpha and Delta variants

Genomic surveillance of SARS-CoV-2 has provided a critical evidence base for public health decisions throughout the pandemic. Sequencing data from clinical cases has helped to understand disease transmission and the spread of novel variants. Genomic wastewater surveillance can offer important, complementary information by providing frequency estimates of all variants circulating in a population without sampling biases. Here we show that genomic SARS-CoV-2 wastewater surveillance can detect fine-scale differences within urban centres, specifically within the city of Liverpool, UK, during the emergence of Alpha and Delta variants between November 2020 and June 2021. Furthermore, wastewater and clinical sequencing match well in the estimated timing of new variant rises and the first detection of a new variant in a given area may occur in either clinical or wastewater samples. The study's main limitation was sample quality when infection prevalence was low in spring 2021, resulting in a lower resolution of the rise of the Delta variant compared to the rise of the Alpha variant in the previous winter. The correspondence between wastewater and clinical variant frequencies demonstrates the reliability of wastewater surveillance. However, discrepancies in the first detection of the Alpha variant between the two approaches highlight that wastewater monitoring can also capture missing information, possibly resulting from asymptomatic cases or communities less engaged with testing programmes, as found by a simultaneous surge testing effort across the city.

FORWARDS-1: an adaptive, single-blind, placebo-controlled ascending dose study of acute baclofen on safety parameters in opioid dependence during methadone-maintenance treatment-a pharmacokinetic-pharmacodynamic study

Background

Treatment of opiate addiction with opiate substitution treatment (e.g. methadone) is beneficial. However, some individuals desire or would benefit from abstinence but there are limited options to attenuate problems with opiate withdrawal. Preclinical and preliminary clinical evidence suggests that the GABA-B agonist, baclofen, has the desired properties to facilitate opiate detoxification and prevent relapse. This study aims to understand whether there are any safety issues in administering baclofen to opioid-dependent individuals receiving methadone.

Methods

Opiate-dependent individuals (DSM-5 severe opioid use disorder) maintained on methadone will be recruited from addiction services in northwest London (NHS and third sector providers). Participants will be medically healthy with no severe chronic obstructive pulmonary disease or type 2 respiratory failure, no current dependence on other substances (excluding nicotine), no current severe DSM-5 psychiatric disorders, and no contraindications for baclofen or 4800 IU vitamin D (placebo). Eligible participants will be randomised in a 3:1 ratio to receive baclofen or placebo in an adaptive, single-blind, ascending dose design. A Bayesian dose-escalation model will inform the baclofen dose (10, 30, 60, or 90 mg) based on the incidence of ‘dose-limiting toxicity’ (DLT) events and participant-specific methadone dose. A range of respiratory, cardiovascular, and sedative measures including the National Early Warning Score (NEWS2) and Glasgow Coma Scale will determine DLT. On the experimental day, participants will consume their usual daily dose of methadone followed by an acute dose of baclofen or placebo (vitamin D3) ~ 1 h later. Measures including oxygen saturation, transcutaneous CO₂, respiratory rate, QTc interval, subjective effects (sedation, drug liking, craving), plasma levels (baclofen, methadone), and adverse events will be obtained using validated questionnaires and examinations periodically for 5 h after dosing.

Discussion

Study outcomes will determine what dose of baclofen is safe to prescribe to those receiving methadone, to inform a subsequent proof-of-concept trial of the efficacy baclofen to facilitate opiate detoxification. To proceed, the minimum acceptable dose is 30 mg of baclofen in patients receiving ≤ 60 mg/day methadone based on the clinical experience of baclofen’s use in alcoholism and guidelines for the management of opiate dependence.

Trial registration

Clinicaltrials.gov NCT05161351. Registered on 16 December 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06821-9.

P06 The use of procalcitonin testing to improve antibiotic stewardship in all cause respiratory admissions: a retrospective analysis

Background

Improving antibiotic stewardship whilst simultaneously optimizing patient safety is a perpetually vexing clinical conundrum, which has been compounded by the current COVID-19 pandemic. Procalcitonin (PCT) measurement has previously demonstrated utility in this regard, when combined with routine clinical investigation, in certain patient populations.

Objectives

To assess whether the inclusion of PCT measurement as part of routine clinical care, instituted during a quality improvement project (QIP), increases the appropriateness of antibiotic administration.

Methods

A retrospective analysis was performed on 6 month interim data obtained from May to October 2021 during a QIP, which assessed the effect of PCT measurement on antimicrobial stewardship. All patients included had a primary diagnosis of respiratory illness and were analysed both together and as COVID-19 and non-COVID-19 subgroups to assess how often antibiotics were commenced on admission, duration of treatment and appropriateness of use. Finally, as sending microbiological samples made up part of the protocol, sample sending frequency was also studied.

Results

Thirty patients were included in both the COVID-19 and non-COVID-19 baseline subgroups who did not have PCT testing performed. Fifty-two patients were included in the PCT subgroup (27 COVID-19 positive and 25 COVID-19 negative). Following introduction of PCT testing, commencement of antibiotics on admission was reduced overall and in the COVID-19 positive subgroup (P = 0.0426 and P = 0.0446, respectively) with a significant decrease in inappropriate antibiotic prescribing in these two groups (P = 0.011 and P = 0.0157, respectively) and a trend towards reduced prescribing of AWaRe watch group antibiotics such as ceftriaxone. However, once prescribed, there was no difference in duration of antibiotic treatment or the frequency of microbiological sampling.

Conclusions

The data from this interim data analysis demonstrate that PCT measurement, when combined with routine clinical investigations in the acute respiratory setting, can be used to reduce inappropriate antibiotic prescribing. This was significantly reduced overall and in the COVID-19 positive subgroup but lost statistical significance in the COVID-19 negative subgroup, where it could be hypothesized that heterogeneity and inclusion of respiratory diseases where PCT has previously encountered difficulty in determining the presence of acute bacterial infection may be the cause. The significant effect demonstrated in the COVID-19 positive subgroup suggests particular utility in this patient population.

Comparison of SERS pH probe responses after microencapsulation within hydrogel matrices

SIGNIFICANCE

Personalized medicine requires the tracking of an individual's metabolite levels over time to detect anomalies and evaluate the body's response to medications. Implanted sensors offer effective means to continuously monitor specific metabolite levels, provided they are accurate, stable over long time periods, and do no harm.

AIM

Four types of hydrogel embedded with pH-sensitive sensors were evaluated for their accuracy, sensitivity, reversibility, longevity, dynamic response, and consistency in static versus dynamic conditions and long-term storage.

APPROACH

Raman spectroscopy was first used to calibrate the intensity of pH-sensitive peaks of the Raman-active hydrogel sensors in a static pH environment. The dynamic response was then assessed for hydrogels exposed to changing pH conditions within a flow cell. Finally, the static pH response after 5 months of storage was determined.

RESULTS

All four types of hydrogels allowed the surface-enhanced Raman spectroscopy (SERS) sensors to respond to the pH level of the local environment without introducing interfering signals, resulting in consistent calibration curves. When the pH level changed, the probes in the gels were slow to reach steady-state, requiring several hours, and response times were found to vary among hydrogels. Only one type, poly(2-hydroxyethyl methacrylate) (pHEMA), lasted five months without significant degradation of dynamic range.

CONCLUSIONS

While all hydrogels appear to be viable candidates as biocompatible hosts for the SERS sensing chemistry, pHEMA was found to be most functionally stable over the long interval tested. Poly(ethylene glycol) hydrogels exhibit the most rapid response to changing pH. Since these two gel types are covalently cross-linked and do not generally degrade, they both offer advantages over sodium alginate for use as implants.

A study to evaluate the primary causes associated with Pseudomonas otitis in 60 dogs

OBJECTIVES

To evaluate the primary causes, age of onset and time from diagnosis of otitis to development of Pseudomonas otitis in each case.

MATERIALS AND METHODS

Data from clinical records of 60 dogs were extracted to address the study objectives. Pseudomonas otitis was diagnosed by clinical signs and positive culture.

RESULTS

In total, 57 purebred dogs and three crossbreed dogs were included: 32 dogs had unilateral and 28 bilateral disease. Underlying primary causes of otitis were allergy (42), masses (8), endocrine disease (7) and autoimmune disease (3). The mean age of onset of otitis (and subsequent time to development of Pseudomonas otitis) in dogs with allergic otitis was 40 months (28 months), with endocrine disease was 56 months (19 months) and masses 99 months (10 months).

CLINICAL SIGNIFICANCE

The most common primary causes of otitis in dogs with Pseudomonas infections are, in decreasing frequency: allergies, masses, endocrine disease and autoimmune disease. Secondary infections with Pseudomonas developed more quickly if there was a mass or autoimmune disease, as compared with allergies and endocrinopathies.

Otitis media with effusion in the boxer: a report of seven cases

The aim of this study was to describe otitis media with effusion in seven boxers. All dogs presented with a range of clinical signs, which included head shaking, neurological dysfunction, pain on opening of the mouth and reduction in hearing ability. Otitis media was confirmed under general anaesthesia in each case by video-otoscopic identification of a bulging pars tensa and subsequent myringotomy, which revealed a tenacious mucus plug within the middle ear. Brainstem auditory evoked response thresholds were elevated in all affected ears. In three cases, CT revealed soft tissue opacity in the affected bulla. All of the affected middle ears were flushed using warm sterile saline to remove the mucus. A combination of glucocorticoid and antibiotic in EDTA tris was instilled into the middle ears. After the initial middle ear flush under general anaesthesia, topical therapy was applied into the ear canals daily by the owners using the same combination of drugs. Dembrexine, a systemic mucolytic, was administered with food daily. Six out of seven dogs were also prescribed oral prednisolone. In each case, the middle ear effusion was sterile. All clinical signs resolved with treatment, with the exception of facial paralysis in two dogs. Otitis media with effusion should be considered a cause of otitis media in boxers.

Enzyme-coated Janus nanoparticles that selectively bind cell receptors as a function of the concentration of glucose

A method is proposed for controlling the number of nanoparticles bound to cell membranes via RGDS peptide-integrin interactions. It consists of propelling nanoparticles bearing the peptides with enzymes (glucose oxidase), which disrupts biomolecular interactions as a function of the concentration of enzyme substrate (glucose).

Light-Triggered Inactivation of Enzymes with Photothermal Nanoheaters

A universal method for inactivating enzymes on demand is introduced, which involves irradiating nanorod-bound enzymes with near-infrared light. The subsequent generation of plasmonic heat denatures the enzymes selectively without damaging other proteins or cell membranes present in the same solution.

Wild rodents as a model to discover genes and pathways underlying natural variation in infectious disease susceptibility

Individuals vary in their susceptibility to infectious disease, and it is now well established that host genetic factors form a major component of this variation. The discovery of genes underlying susceptibility has the potential to lead to improved disease control, through the identification and management of vulnerable individuals and the discovery of novel therapeutic targets. Laboratory rodents have proved invaluable for ascertaining the function of genes involved in immunity to infection. However, these captive animals experience conditions very different to the natural environment, lacking the genetic diversity and environmental pressures characteristic of natural populations, including those of humans. It has therefore often proved difficult to translate basic laboratory research to the real world. In order to further our understanding of the genetic basis of infectious disease resistance, and the evolutionary forces that drive variation in susceptibility, we propose that genetic research traditionally conducted on laboratory animals is expanded to the more ecologically valid arena of natural populations. In this article, we highlight the potential of using wild rodents as a new resource for biomedical research, to link the functional genetic knowledge gained from laboratory rodents with the variation in infectious disease susceptibility observed in humans and other natural populations.

Topical ear treatment - options, indications and limitations of current therapy

Topical otic products form an integral part of the overall management of otitis externa. With an ever increasing array of ear drops and cleaners to choose from, appropriate selection of therapy can be difficult. The investigation of all cases of otitis externa should consider primary and secondary causes and predisposing and perpetuating factors. This article considers topical therapy under these same broad headings and discusses, through literature review, the various properties of the components of the ear cleaning solutions and drops.

Self-assembly of gold supraparticles with crystallographically aligned and strongly coupled nanoparticle building blocks for SERS and photothermal therapy

A new method is introduced for self-assembling citrate-capped gold nanoparticles into supraparticles with crystallographically aligned building blocks. It consists in confining gld nanoparticles inside a cellulose acetate membrane. The constituent nanoparticles are in close contact in the superstructure, and therefore generate hot spots leading to intense Surface-Enhanced Raman Scattering (SERS) signals. They also generate more plasmonic heat than the nanoparticle building blocks. The supraparticles are internalized by cells and show low cytotoxicity, but can kill cancer cells when irradiated with a laser. This, along with the improved plasmonic properties arising from their assembly, makes the gold supraparticles promising materials for applications in bioimaging and nanomedicine.

Effect of Deception of Distance on Prolonged Cycling Performance

This study examined the effect of deception of distance end-point on prolonged cycling performance. 21 subjects were randomly allocated to three groups ( n = 7 per group). Each group completed three self-paced time-trials separated by one day. Subjects were told that each trial was a 30-km time-trial and were required to complete the distance in the fastest time possible. Following the initial trial of 30 km, one group completed Trial 2 with a longer distance (long distance group; 36 km), another group with a shorter distance (24 km; short distance group), and the third group as control (30 km; control). Each group then completed a third time-trial of 30 km. At no time was the deception of distance in Trial 2 disclosed to the subjects, and all sources of physiological and mechanical feedback were withheld during the trials. Data from Trials 1 and 3 were analysed by repeated-measures analysis of covariance. Time to complete Trial 1 was similar among groups (–65 min.). Following the deception in Trial 2 the time to complete the 30 km in Trial 3 was increased for the short distance group, decreased for the long distance group, whilst the time for the control group remained unchanged. The times to complete the 30 km on Trials 1 and 3 were matched by changes in power output throughout the trials. It is concluded that subjects deceived of the actual distance completed will complete the subsequent performance trial based on perceived effort rather than on actual distance.

Transcriptional changes during Daphnia pulex development indicate that the maturation decision resembles a rate more than a threshold

Maturation is a critical developmental process, and the age and size at which it occurs have important fitness consequences. Although maturation is remarkably variable, certain mechanisms, including a minimum size or state threshold, are proposed to underlie the process across a broad diversity of taxa. Recent evidence suggests that thresholds may themselves be developmentally plastic, and in the crustacean Daphnia pulex it is unclear whether maturation follows a threshold or is a gradual process more akin to a rate. Changes in gene expression across four instars before and during maturation were compared in a cDNA microarray experiment. Developmental stage was treated statistically both as a discontinuous and as a continuous variable, to determine whether genes showed gradual or discrete changes in expression. The continuous analysis identified a greater number of genes with significant differential expression (45) than the discontinuous analysis (11). The majority of genes, including those coding for histones, factors relating to transcription and cell cycle processes, and a putative developmental hormone showed continuous increases or decreases in expression from the first to the fourth instars that were studied, suggestive of a prolonged and gradual maturation process. Three genes coding for a fused vitellogenin/superoxide dismutase showed increases in expression following the second instar and coincided with the posited maturation threshold, but even their expression increased in a continuous fashion.

Solution-based nanosensors for in-field detection with the naked eye

Nanomaterials are revolutionising analytical applications with low-cost tests that enable detecting a target molecule in a few steps and with the naked eye.

Laparoscopic nephrectomy for adult polycystic kidney disease: safety, feasibility, and early outcomes

BACKGROUND AND PURPOSE

Indications for laparoscopic renal surgery are increasing; however, benefits in adult polycystic kidney disease (APKD) remain uncertain. Our objective was to systematically synthesize the reported literature on safety, feasibility, complications, and early outcomes of laparoscopic nephrectomy in APKD to determine clinical benefits for surgical practice.

METHODS

We conducted a meta-analysis of the published literature reporting on laparoscopic nephrectomy in APKD between 1991 and 2013. The criteria from the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) study were used to assess the quality of reported literature.

RESULTS

One prospective and 15 retrospective studies of low to modest quality (according to the STROBE checklist) were identified, reporting on 293 patients who underwent laparoscopic nephrectomy for APKD. None of the studies was a randomized clinical trial (RCT). The transperitoneal approach was the most commonly used technique. Body mass index ranged from 16 to 57 (mean 26.2 kg/m(2); 53% of patients were dialysis dependent, and 31% had a previous or simultaneous transplant. Kidney length ranged from 8 to 50 cm (mean 34.5cm), and the mean mass of affected kidneys was 1647 g (range 132 g-7200 g). Duration of hospital stay ranged from 2.6 to 11 days (mean 4.9 days). Operative time ranged from 90 to 568 minutes, with 16.2% of patients needing blood transfusion. There were 24 intraoperative complications and 68 postoperative complications, a rate of 8% and 24%, respectively. A total of 16 (5%) cases were converted to an open technique. No mortality was reported in any of the included studies.

CONCLUSION

The quality of the included studies is poor, and it is difficult to argue for or against change in clinical practice because the evidence included is of level 3 and 4 only. Higher quality studies are needed to demonstrate that the technique is generalizable across all populations.

Network inefficiencies in autism spectrum disorder at 24 months

Autism spectrum disorder (ASD) is a developmental disorder defined by behavioral symptoms that emerge during the first years of life. Associated with these symptoms are differences in the structure of a wide array of brain regions, and in the connectivity between these regions. However, the use of cohorts with large age variability and participants past the generally recognized age of onset of the defining behaviors means that many of the reported abnormalities may be a result of cascade effects of developmentally earlier deviations. This study assessed differences in connectivity in ASD at the age at which the defining behaviors first become clear. There were 113 24-month-old participants at high risk for ASD, 31 of whom were classified as ASD, and 23 typically developing 24-month-old participants at low risk for ASD. Utilizing diffusion data to obtain measures of the length and strength of connections between anatomical regions, we performed an analysis of network efficiency. Our results showed significantly decreased local and global efficiency over temporal, parietal and occipital lobes in high-risk infants classified as ASD, relative to both low- and high-risk infants not classified as ASD. The frontal lobes showed only a reduction in global efficiency in Broca's area. In addition, these same regions showed an inverse relation between efficiency and symptom severity across the high-risk infants. The results suggest delay or deficits in infants with ASD in the optimization of both local and global aspects of network structure in regions involved in processing auditory and visual stimuli, language and nonlinguistic social stimuli.

Detecting genes for variation in parasite burden and immunological traits in a wild population: testing the candidate gene approach

Identifying the genes underlying phenotypic variation in natural populations can provide novel insight into the evolutionary process. The candidate gene approach has been applied to studies of a number of traits in various species, in an attempt to elucidate their genetic basis. Here, we test the application of the candidate gene approach to identify the loci involved in variation in gastrointestinal parasite burden, a complex trait likely to be controlled by many loci, in a wild population of Soay sheep. A comprehensive literature review, Gene Ontology databases, and comparative genomics resources between cattle and sheep were used to generate a list of candidate genes. In a pilot study, these candidates, along with 50 random genes, were then sequenced in two pools of Soay sheep; one with low gastrointestinal nematode burden and the other high, using a NimbleGen sequence capture experiment. Further candidates were identified from single nucleotide polymorphisms (SNPs) that were highly differentiated between high- and low-resistance sheep breeds. A panel of 192 candidate and control SNPs were then typed in 960 individual Soay sheep to examine whether they individually explained variation in parasite burden, as measured as faecal egg count, as well as two immune measures (Teladorsagia circumcincta-specific antibodies and antinuclear antibodies). The cumulative effect of the candidate and control SNPs were estimated by fitting genetic relationship matrices (GRMs) as random effects in animal models of the three traits. No more significant SNPs were identified in the pilot sequencing experiment and association study than expected by chance. Furthermore, no significant difference was found between the proportions of candidate or control SNPs that were found to be significantly associated with parasite burden/immune measures. No significant effect of the candidate or control gene GRMs was found. There is thus little support for the candidate gene approach to the identification of loci explaining variation in parasitological and immunological traits in this population. However, a number of SNPs explained significant variation in multiple traits and significant correlations were found between the proportions of variance explained by individual SNPs across multiple traits. The significant SNPs identified in this study may still, therefore, merit further investigation.

Rotation and translational motion prior to self-assembly: dynamics of ethanethiolate on Cu(111)

We investigate the dynamics of low-coverage ethanethiolate on Cu(111) using helium spin-echo spectroscopy. Above 210 K, the measurements are dominated by translational hopping with an activation energy of only 86 ± 5 meV. At lower temperatures (150-210 K) a further process becomes apparent which has the signature of confined motion. We demonstrate the experimental results are consistent with scattering from an anchored rotor, enabling identification of sixfold jump rotation of the ethyl tail group around a static sulfur adsorption site, with a rotational activation energy of 18 ± 8 meV. Our approach represents a new form of rotational spectroscopy which can be used to study rotational surface diffusion.

Transcriptomic response of red grouse to gastro-intestinal nematode parasites and testosterone: implications for population dynamics

A central issue in ecology is in understanding the relative influences of intrinsic and extrinsic effects on population regulation. Previous studies on the cyclic population dynamics of red grouse (Lagopus lagopus scoticus) have emphasized the destabilizing effects of either nematode parasites or territorial behaviour and aggression. The potential interacting effects of these processes, mediated through density-dependent, environmentally induced alterations of host immunocompetence influencing susceptibility to parasites have not been considered. Male red grouse at high density are more aggressive, associated with increased testosterone, which potentially could lead to reduced immunocompetence at a stage when parasites are most prevalent. This could depress individual condition, breeding performance and survival and thus drive or contribute to overall reductions in population size. Here, we characterize the transcriptomic response of grouse to nematode parasite infection and investigate how this is subsequently affected by testosterone, using a microarray approach contrasting red grouse with high and low parasite load at both high and low testosterone titre. A suite of 52 transcripts showed a significant level of up-regulation to either chronic parasite load or experimental parasite infection. Of these, 51 (98%) showed a reduced level of expression under conditions of high parasite load and high testosterone. The genes up-regulated by parasites and then down-regulated at high testosterone titre were not necessarily associated with immune response, as might be intuitively expected. The results are discussed in relation to the fitness and condition of individual red grouse and factors influencing the regulation of abundance in natural populations.

Identification of genes responding to nematode infection in red grouse

The identification of genes involved in a host's response to parasite infection provides both a means for understanding the pathways involved in immune defence and a target for examining host-parasite co-evolution. Most studies rely on a candidate gene approach derived from model systems to identify gene targets of interest, and there have been a dearth of studies geared towards providing a holistic overview of immune response from natural populations. We carried out an experiment in a natural population of red grouse (Lagopus lagopus scoticus) to manipulate levels of Trichostrongylus tenuis parasite infection. The transcriptomic response of individuals was examined from standard cDNA and suppressive subtractive hybridization (SSH) libraries produced from gut, liver and spleen, enriching for genes expressed in response to T. tenuis infection. A total of 2209 and 3716 unique transcript sequences were identified from the cDNA and SSH libraries, respectively. Forty-five of these had Gene Ontology annotation associated with immune response. Some of these genes have previously been reported from laboratory-based studies of model species as important in immune response to gastrointestinal parasite infection; however, multiple novel genes were also identified. These may reveal novel pathways involved in the host response of grouse to T. tenuis and provide a resource that can be utilized as candidate genes in other species. All sequences described have been deposited in GenBank (accession numbers GW698221-GW706922)

How effective is recognition of siblings on the basis of genotype?

The ability to recognize kin based on genetic markers has been widely proposed as a mechanism to facilitate altruistic behaviour and inbreeding avoidance. Siblings are an important group of relatives to discriminate from unrelated individuals but present a problem, because siblings can share 0, 1 or 2 alleles at any single recognition locus. Here, we present a Bayesian model of kin recognition that defines the potential for genotypic information to convey kinship. Under the direct comparison model, where the signaller's genotype is compared with that of the receiver, the odds ratio that a pair of individuals were siblings was substantially increased if they shared both alleles at a single locus, but only a minority of siblings were recognized; increasing the number of recognition loci used could not increase both the odds ratio and the proportion of siblings recognized. A maternal comparison model, where the signaller's genotype is compared with that of the receiver's mother, performed poorly when only a single recognition locus was considered, but became increasingly effective with more recognition loci. Nevertheless, incorporating partial-matching information across multiple, independent loci are likely to be difficult. Further empirical work needs to establish the mechanistic basis of genetic kin recognition used by different taxa.

Fat transforms ascorbic acid from inhibiting to promoting acid-catalysed N-nitrosation

BACKGROUND

The major potential site of acid nitrosation is the proximal stomach, an anatomical site prone to a rising incidence of metaplasia and adenocarcinoma. Nitrite, a pre-carcinogen present in saliva, can be converted to nitrosating species and N-nitroso compounds by acidification at low gastric pH in the presence of thiocyanate.

AIMS

To assess the effect of lipid and ascorbic acid on the nitrosative chemistry under conditions simulating the human proximal stomach.

METHODS

The nitrosative chemistry was modelled in vitro by measuring the nitrosation of four secondary amines under conditions simulating the proximal stomach. The N-nitrosamines formed were measured by gas chromatography-ion-trap tandem mass spectrometry, while nitric oxide and oxygen levels were measured amperometrically.

RESULTS

In absence of lipid, nitrosative stress was inhibited by ascorbic acid through conversion of nitrosating species to nitric oxide. Addition of ascorbic acid reduced the amount of N-nitrosodimethylamine formed by fivefold, N-nitrosomorpholine by >1000-fold, and totally prevented the formation of N-nitrosodiethylamine and N-nitrosopiperidine. In contrast, when 10% lipid was present, ascorbic acid increased the amount of N-nitrosodimethylamine, N-nitrosodiethylamine and N-nitrosopiperidine formed by approximately 8-, 60- and 140-fold, respectively, compared with absence of ascorbic acid.

CONCLUSION

The presence of lipid converts ascorbic acid from inhibiting to promoting acid nitrosation. This may be explained by nitric oxide, formed by ascorbic acid in the aqueous phase, being able to regenerate nitrosating species by reacting with oxygen in the lipid phase.

The immune response during a Strongyloides ratti infection of rats

A range of immune parameters was measured during a primary infection of Strongyloides ratti in its natural rat host. The immune parameters measured were interleukin-4 (IL-4) and interferon-gamma from both the spleen and mesenteric lymph node (MLN) cells; parasite-specific immunoglobulin G(1)(IgG(1)), IgG(2a) and IgG(2b) in serum and in intestinal tissue; parasite-specific IgG and total IgE in serum; parasite-specific and total IgA in intestinal tissue and rat mast cell protease II in intestinal tissue. Parasite-specific IgG(1), IgG(2a) and total IgE in serum and parasite-specific IgA and rat mast cell protease II in intestinal tissue all occurred at significantly greater concentrations in infected animals, compared with non-infected animals. Similarly, the production of IL-4 by MLN cells stimulated with parasitic female antigen or concanavalin A occurred at significantly greater concentrations in infected animals, compared with non-infected animals. In all, this suggests that there is a T-helper 2-type immune response during a primary S. ratti infection. These data also show the temporal changes in these components of the host immune response during a primary S. ratti infection.

Validation of techniques to detect illicit heroin use in patients prescribed pharmaceutical heroin for the management of opioid dependence

BACKGROUND

The clinical implementation and evaluation of heroin substitution programmes have been confounded by the lack of objective and validated biomarkers for illicit heroin use in patients prescribed pharmaceutical heroin. This study examined the capacity to detect illicit heroin use by gas chromatography-mass spectrometry (GC-MS) analysis of urine samples for the presence of opium impurities common to illicit, but not pharmaceutical heroin.

AIMS

To characterize the diagnostic properties of the metabolites of noscapine and papaverine in comparison to morphine as a gold-standard marker of illicit heroin use; and to examine the relationships between the self-reported time since most recent heroin use and the detection of these opioids in urine.

DESIGN

A cross-sectional study of 52 opioid-dependent patients in treatment (not prescribed heroin), who self-reported illicit heroin use within the preceding 2 weeks. Self-report data regarding recent drug use and a urine sample were collected. GC-MS analyses of urines were conducted and reported by laboratory staff blinded to self-report data.

FINDINGS

The metabolites of papaverine (hydroxypapaverine and dihydroxypapeverine) were found to have high sensitivity, specificity and negative predictive values as markers for illicit heroin use compared to the 'gold-standard' morphine. Other opioids, including 6-mono-acetylmorphine (6-MAM), codeine and noscapine metabolites (e.g. meconine) were less adequate in detecting heroin use.

CONCLUSIONS

GC-MS detection of papaverine metabolites in urine appears to be suitable method of identifying illicit heroin use for clinical and research purposes.