The Pandemic Paranoia Scale (PPS): factor structure and measurement invariance across languages.

BACKGROUND: Globally, the corona virus disease 2019 (COVID-19) pandemic has created an interpersonally threatening context within which other people have become a source of possible threat. This study reports on the development and validation of a self-report measure of pandemic paranoia; that is, heightened levels of suspicion and mistrust towards others due to the COVID-19 pandemic. METHODS: An international consortium developed an initial set of 28 items for the Pandemic Paranoia Scale (PPS), which were completed by participants from the UK (n = 512), USA (n = 535), Germany (n = 516), Hong Kong (n = 454) and Australia (n = 502) using stratified quota sampling (for age, sex and educational attainment) through Qualtrics and translated for Germany and Hong Kong. RESULTS: Exploratory factor analysis in the UK sample suggested a 25-item, three-factor solution (persecutory threat; paranoid conspiracy and interpersonal mistrust). Confirmatory factor analysis (CFA) on the remaining combined sample showed sufficient model fit in this independent set of data. Measurement invariance analyses suggested configural and metric invariance, but no scalar invariance across cultures/languages. A second-order factor CFA on the whole sample indicated that the three factors showed large loadings on a common second-order pandemic paranoia factor. Analyses also supported the test-retest reliability and internal and convergent validity. CONCLUSION: The PPS offers an internationally validated and reliable method for assessing paranoia in the context of a pandemic. The PPS has the potential to enhance our understanding of the impact of the pandemic, the nature of paranoia and to assist in identifying and supporting people affected by pandemic-specific paranoia.

Low-Energy Physics Reach of Xenon Detectors for Nuclear-Recoil-Based Dark Matter and Neutrino Experiments.

Dual-phase xenon detectors lead the search for keV-scale nuclear recoil signals expected from the scattering of weakly interacting massive particle (WIMP) dark matter, and can potentially be used to study the coherent nuclear scattering of MeV-scale neutrinos. New capabilities of such experiments can be enabled by extending their nuclear recoil searches down to the lowest measurable energy. The response of the liquid xenon target medium to nuclear recoils, however, is not well characterized below a few keV, leading to large uncertainties in projected sensitivities. In this work, we report a new measurement of ionization signals from nuclear recoils in liquid xenon down to the lowest energy reported to date. At 0.3 keV, we find that the average recoil produces approximately one ionization electron; this is the first measurement of nuclear recoil signals at the single-ionization-electron level, approaching the physical limit of liquid xenon ionization detectors. We discuss the implications of these measurements on the physics reach of xenon detectors for nuclear-recoil-based WIMP dark matter searches and the detection of coherent elastic neutrino-nucleus scattering.

Development of ISSR-derived SCAR marker-targeted PCR for identification of Aspergillus section Flavi members.

UNLABELLED: Aspergillus section Flavi is a heterogeneous fungal cluster including some of the most economically important Aspergillus species. The section is comprised of toxigenic and nontoxigenic aspergilli that are phenotypically undistinguishable. The aim of this study was to develop a genetic marker specific to Aspergillus section Flavi on the whole. Based on inter-simple sequence repeat (ISSR) fingerprinting profiles of major Aspergillus section Flavi members, a sequence-characterized amplified region (SCAR) marker was identified. Primers were designed in the conserved regions of the SCAR marker and were utilized in a PCR for concurrent identification of major members of the section. The detection level of the SCAR-PCR was found to be 0·1 ng purified DNA, and when applied to 45 naturally contaminated food samples, 28 samples were found infected with Aspergillus section Flavi members. The present SCAR-PCR is rapid and less cumbersome unlike conventional identification techniques. SIGNIFICANCE AND IMPACT OF THE STUDY: Identification of Aspergillus section Flavi members is important owing to their impact on human health and economy. The ISSR-based SCAR-PCR developed in this study is superior over the other existing Aspergillus section Flavi detection systems due to its simplicity and minimal requirement of sample handling. This PCR could be a supplementary strategy to time-consuming and rather ambiguous conventional polyphasic detection techniques and a reliable tool for high-throughput sample analysis.

Measuring Paranoid Beliefs in Adolescents: A Comparison of the Revised-Green et al.'s Paranoid Thoughts Scale (R-GPTS) and the Bird Checklist of Adolescent Paranoia (B-CAP).

Research on paranoid beliefs in adolescents is in its infancy. Valid and reliable assessments are essential to advancing the field, yet there is no current consensus as to which are optimal to use in this population. This study compared the psychometric properties of two measures of paranoia in a general population adolescent sample. A cross-sectional study with quota sampling (gender and age) recruited adolescents (14-17 years) from the UK (n = 262) and USA (n = 200), who completed the Revised Green et al. Paranoid Thoughts Scale (R-GPTS) and the Bird Checklist for Adolescent Paranoia (B-CAP). We assessed factor structures, intercorrelations, overlap of participants identified as at-risk for paranoid thoughts via both scales, convergent validity (scales with one another) and discriminant validity (distress, wellbeing, bullying and discrimination). Both scales performed equally well in terms of factorial validity. Intercorrelations between the subscales and with general distress were high for both measures. However, a substantial percentage of participants were identified as having paranoid beliefs according to the R-GPTS but not the B-CAP. Furthermore, the B-CAP showed a very high correlations (0.69 ≤ r ≤ 0.79) with self-reported bullying experiences, which bordered on multicollinearity. Findings highlight the possibility that B-CAP may risk confounding paranoid beliefs with exposure to bullying more so than R-GPTS, and that B-CAP may miss instances of elevated paranoia that are captured by the R-GPTS. Future research needs to further explore this by validating both scales with an external (e.g., interview-based) criterion for paranoia.

Second and subsequent tumours among 1927 retinoblastoma patients diagnosed in Britain 1951-2004.

BACKGROUND: Retinoblastoma is an eye tumour of childhood that occurs in heritable and non-heritable forms. In the heritable form, there is a predisposition to the development of non-ocular subsequent primary tumours (SPTs). METHODS: This study included 1927 retinoblastoma patients diagnosed in Britain from 1951 to 2004. Ascertainment was through the (UK) National Registry of Childhood Tumours; cases were followed-up for the occurrence of SPTs. Standardised incidence ratios (SIRs) were calculated. RESULTS: We identified 169 SPTs in 152 patients. The SIR analysis included 145 SPTs with cancer registrations from the years 1971 to 2009. These tumours occurred in 132 patients: 112 of the 781 heritable and 20 of the 1075 (presumed) non-heritable cases under surveillance at the start of this period developed at least one registered SPT. The SIRs for all tumours combined were 13.7 (95% confidence interval 11.3-16.5) in heritable cases and 1.5 (0.9-2.3) in non-heritable cases. The main types of SPT in the heritable cases were leiomyosarcoma, (31 cases; SIR 1018.7 (692.2-1446.0)), osteosarcoma (26 cases; SIR 444.6 (290.4-651.4)), and skin melanoma (12 cases; SIR 18.6 (9.6-32.4)). CONCLUSION: The risk of SPTs in heritable retinoblastoma is extremely high. This has important implications for the clinical follow-up and counselling of survivors and their families.

Paranoid Thinking as a Function of Minority Group Status and Intersectionality: An International Examination of the Role of Negative Beliefs.

BACKGROUND: Paranoia is higher in minority group individuals, especially those reporting intersecting aspects of difference. High negative and low positive self and other beliefs, and low social rank, are predictive of paranoia overtime; however, data are typically from majority group participants. This study examined whether social defeat or healthy cultural mistrust best characterizes paranoia in minority groups. STUDY DESIGN: Using cross-sectional, survey design, with a large (n = 2510) international sample, moderation analyses (PROCESS) examined whether self and other beliefs, and perceived social rank, operate similarly or differently in minority vs majority group participants. Specifically, we tested whether beliefs moderated the influence of minority group, and intersecting aspects of difference, on paranoia. STUDY RESULTS: Paranoia was consistently higher in participants from minority vs majority groups and level of paranoid thinking was significantly higher at each level of the intersectionality index. Negative self/other beliefs were associated with elevated paranoia in all participants. However, in support of the notion of healthy cultural mistrust, low social rank, and low positive self/other beliefs were significantly associated with paranoia in majority group participants but unrelated to paranoia in respective minority group members. CONCLUSIONS: Although mixed, our findings signal the need to consider healthy cultural mistrust when examining paranoia in minority groups and bring into question whether "paranoia" accurately describes the experiences of marginalized individuals, at least at low levels of severity. Further research on paranoia in minority groups is crucial to developing culturally appropriate ways of understanding people's experiences in the context of victimization, discrimination, and difference.

Generation and characterization of an inter-generic bivalent alpha domain fusion protein αCS from Clostridium perfringens and Staphylococcus aureus for concurrent diagnosis and therapeutic applications.

AIM: To evaluate an inter-generic recombinant alpha domain fusion protein for simultaneous detection and neutralization of Clostridium perfringens and Staphylococcus aureus alpha toxins. METHODS AND RESULTS: Truncated portions of clostridial and staphylococcal alpha haemolysin genes were PCR amplified and linked to each other through a hydrophilic flexible Glycine linker sequence using overlap-extension PCR to form a chimeric gene αCS. The recombinant αCS fusion protein was expressed and characterized for its toxicity, cell binding capacity and haemolysis inhibition properties. The fusion protein was nontoxic and effectively retarded staphylococcal alpha haemolysis, probably by competitively interacting with putative staphylococcal alpha haemolysin receptors on erythrocytes. Murine hyperimmune polysera raised against r-αCS specifically detected 42-kDa and 33-kDa proteins when culture supernatants of Cl. perfringens (clostridial alpha toxin) and Staph. aureus (staphylococcal alpha toxin), respectively, were analysed in Western blot. The polyclonal antisera effectively diminished the haemolytic action of both the wild-type toxins in vitro. CONCLUSIONS: The r-αCS fusion protein was nontoxic competitive inhibitor of staphylococcal alpha haemolysin. The protein elicited specific immune response against Cl. perfringens and Staph. aureus alpha toxins. The antisera also neutralized the toxicities of both the native wild-type toxins in vitro. SIGNIFICANCE OF THE STUDY: The bivalent recombinant αCS protein could be a novel intervention in the field of diagnostics and therapeutics against Cl. perfringens and Staph. aureus infections, particularly, in case of co-infections like gangrenous ischaemia, gangrenous mastitis, etc.

Comparative evaluation of the immunodominant proteins of Brucella abortus for the diagnosis of cattle brucellosis.

BACKGROUND AND AIM: The present serodiagnosis of brucellosis in livestock is based on the whole cell or smooth lipopolysaccharide of the Brucella organism in which specificity is hampered by the cross-reactivity, especially with the antibodies against Yersinia enterocolitica O:9 organism. The problem can be addressed by screening for better immunodominant antigens. Hence, the present study was undertaken to screen protein antigens of Brucella abortus for their diagnostic potential in cattle brucellosis. MATERIALS AND METHODS: Protein antigens of B. abortus (n=10) non-reactive to antibodies against Y. enterocolitica O:9 were selected, expressed in Escherichia coli, assessed the reactivity of expressed recombinant proteins by Western blot, standardized indirect-enzyme-linked immunosorbent assay (ELISA) for detecting Brucella antibodies in cattle serum, and comparative evaluation was done. RESULTS: All the selected protein antigens were expressed and in the Western blot with Brucella antibodies positive cattle serum, six recombinant (Brucella protein 26 [BP26], Cu-Zn Superoxide dismutase [SodC], B. abortus I-1885, Serine protease, Bacterioferritin, and Brucella Lumazine Synthase [BLS]) proteins showed reaction whereas none of the proteins showed reactivity with Brucella negative cattle serum. ELISA has been done using known Brucella positive and negative cattle sera samples (n=113 each) in which the performance of recombinant proteins in diagnosing brucellosis was in the order of BP26 > BLS > SodC followed by rest of the proteins. BP26 based ELISA was found to be better with area under the curve as 0.953, and diagnostic sensitivity, diagnostic specificity, and Youden's index of 90.27%, 95.58%, and 0.8584, respectively, with the excellent agreement (k=0.85). CONCLUSION: BP26 could be a potential diagnostic antigen among the immunodominant proteins of B. abortus in ruling out Y. enterocolitica O:9 infection while diagnosing brucellosis in cattle herds.

Molecular characterization of lactic acid bacteria recovered from natural fermentation of beet root and carrot Kanji.

The lactic acid bacteria (LAB) play an important role in the fermentation of vegetables to improve nutritive value, palatability, acceptability, microbial quality and shelf life of the fermented produce. The LAB associated with beetroot and carrot fermentation were identified and characterized using different molecular tools. Amplified ribosomal DNA restriction analysis (ARDRA) provided similar DNA profile for the 16 LAB strains isolated from beetroot and carrot fermentation while repetitive extragenic palindromic PCR (rep-PCR) genotyping could differentiate the LAB strains into eight genotypes. Thirteen strains represented by five genotypes could be clustered in five distinct groups while three LAB strains exhibiting distinct genotypes remained ungrouped. These genotypes could be identified to be belonging to L. plantarum group by 16S rDNA sequencing. The recAnested multiplex PCR employing species-specific primers for the L. plantarum group members identified the LAB strains of six genotypes to be L. paraplantarum and the other two genotypes to be L. pentosus. Three genotypes of L. paraplantarum were consistently found on the third and sixth day of beetroot fermentation whereas a distinct genotype of L. paraplantarum and L. pentosus appeared predominant on the tenth day. From carrot Kanji two distinct genotypes of L. paraplantarum and one genotype of L. pentosus were identified. REP-PCR DNA fingerprinting coupled with 16S rDNA sequencing and recA-nested multiplex PCR could clearly identify as well as differentiate the diverse L. plantarum group strains involved in the fermentation.

A randomised trial comparing a brief online delivery of mindfulness-plus-values versus values only for symptoms of depression: Does baseline severity matter?

BACKGROUND: Acceptance/mindfulness-based interventions often focus on (a) developing dispositional mindfulness and (b) pursuing personally meaningful and valued activities. Acceptance/mindfulness-based interventions can reduce depression, but little is known about the combined effects of components or the influence of baseline variables on outcomes. This study tested whether practicing a brief (10-min) mindfulness meditation over a 2-week period followed by a single values session (mindfulness+values) was more effective than values alone (values only) in reducing symptoms of depression. The study was delivered online and modules were fully self-help (i.e., no therapist contact). METHODS: 206 participants (Mage=23.4 years, SD=6.53) with elevated depression scores (DASS-depression ≥ 10) were randomised to: mindfulness+values condition or a 2-week wait period followed by the values session (i.e., values only condition). Symptoms of depression were assessed at baseline, after the 2-week mindfulness practice/wait period, and 1-week following the values session. RESULTS: Reductions in depression and recovery rates were significantly greater following mindfulness+values than values only. Baseline severity affected outcomes: mindfulness+values was significantly more beneficial than values only for individuals with high baseline levels of depression. Outcomes did not differ for those with low levels of depression. Rates of deterioration were higher than expected for values only participants. LIMITATIONS: Conclusions are preliminary and tentative due to no follow-up period and a small sample. Drop-out was high (50%) and findings cannot be assumed to generalise to treatment seeking or more diverse samples. CONCLUSIONS: Tentatively, results suggest mindfulness+values can significantly reduce depression, especially for individuals with higher baseline depression.

Isotopic evidence for neogene hominid paleoenvironments in the kenya rift valley.

Bipedality, the definitive characteristic of the earliest hominids, has been regarded as an adaptive response to a transition from forested to more-open habitats in East Africa sometime between 12 million and 5 million years ago. Analyses of the stable carbon isotopic composition (delta(13)C) of paleosol carbonate and organic matter from the Tugen Hills succession in Kenya indicate that a heterogeneous environment with a mix of C3 and C4 plants has persisted for the last 15.5 million years. Open grasslands at no time dominated this portion of the rift valley. The observed delta(13)C values offer no evidence for a shift from more-closed C3 environments to C4 grassland habitats. If hominids evolved in East Africa during the Late Miocene, they did so in an ecologically diverse setting.

A hominoid genus from the early Miocene of Uganda.

Fossils from a large-bodied hominoid from early Miocene sediments of Uganda, along with material recovered in the 1960s, show features of the shoulder and vertebral column that are significantly similar to those of living apes and humans. The large-bodied hominoid from Uganda dates to at least 20.6 million years ago and thus represents the oldest known hominoid sharing these derived characters with living apes and humans.

Antimicrobial susceptibility and molecular characterization of Vibrio cholerae from cholera outbreaks in Chennai.

The genotype and antibiotic resistance pattern of the toxigenic Vibrio cholerae strains associated with cholera outbreaks vary frequently. Fifty-one V. cholerae strains isolated from cholera outbreaks in Chennai (2002-2005) were screened for the presence of virulence and regulatory genes by multiplex polymerase chain reaction (PCR) assay. Genotyping of the isolates was done by VC1 primers derived from enterobacterial repetitive intergenic consensus (ERIC)-related sequence in V. cholerae. All the isolates possessed toxigenic genes, such as ctxA, ctxB, tcpA, ace, ompU, toxR and zot. Two different El Tor genotypes and one O139 genotype could be delineated by VC1-PCR. One of the El Tor genotypes was similar to the El Tor strains isolated from Bhind district and Delhi during 2004. Antibiotic susceptibility testing revealed greater variability among the isolates tested. All the isolates were found to be susceptible to norfloxacin, ciprofloxacin and tetracycline. Thiry-three per cent of the isolates were found to be resistant to more than 4 antibiotics and could be termed as multiple antibiotic resistant. Coexistence of O139 serogroup along with the El Tor biotype could be identified among the strains recovered during the period 2002-2004. The O139 isolates were found to be more susceptible to the antibiotics tested when compared to the El Tor isolates.

A bivalent protein r-PB, comprising PA and BclA immunodominant regions for comprehensive protection against Bacillus anthracis.

Anthrax infection is primarily initiated by B. anthracis endospores that on entry into the host germinate to vegetative cells and cause severe bacteremia and toxaemia employing an array of host colonisation factors and the lethal tripartite toxin. The protective efficacy of conventional protective antigen (PA) based anthrax vaccines is improved by co-administration with inactivated spores or its components. In the present study, using structural vaccinology rationale we synthesized a bivalent protein r-PB encompassing toxin (PAIV) and spore components (BclACTD) and characterized its protective efficacy against B. anthracis infection. Active immunization of mice with r-PB generated high titer circulating antibodies which facilitated the phagocytic uptake of spores, inhibited their germination to vegetative cells and completely neutralized anthrax toxins in vivo resulting in 100 % survival against anthrax toxin challenge. Proliferation of CD4+ T cell subsets with up-regulation of Th1 (IFN-γ, IL-2, and IL-12), Th2 (IL-5, IL-10) cytokines and balanced expression of IgG1:IgG2a antibody isotypes indicated the stimulation of both Th1 and Th2 subsets. The immunized mice exhibited 100 % survival upon challenge with B. anthracis spores or toxin indicating the ability of r-PB to provide comprehensive protection against anthrax. Our results thus demonstrate r-PB an efficient vaccine candidate against anthrax infection.

Retinoblastoma incidence and survival in European children (1978-1997). Report from the Automated Childhood Cancer Information System project.

Based on 2283 cases of retinoblastoma diagnosed in children aged 0-14 years, incidence and survival in Europe during the period 1978-1997 are described. Data were provided to the Automated Childhood Cancer Information System (ACCIS) from 60 paediatric and general cancer registries. During 1988-1997, the cumulative incidence of retinoblastoma in the ACCIS regions was found to be between 44.2 and 67.9 per million births. The highest incidence was seen in the first year of life. The age-standardised (World standard) incidence rate for the age-range 0-14 years was 4.1 per million. Approximately one-third of cases had bilateral tumours. Overall incidence increased over the period 1978-1997 by 1% per year, as derived from a model adjusted for sex, age group and type of registry (general or paediatric). The 5-year survival rate improved from 89% to 95% during the period covered by the study. This improvement was seen in both unilateral and bilateral cases but was significant only for the unilateral tumours. Survival was lower in the East region, although smaller differences were also observed between the other four regions (British Isles, North, South and West). Availability and quality of registration data on retinoblastoma need to be improved for effective evaluation of incidence and survival.

Vitreous relapse following primary chemotherapy for retinoblastoma: is adjuvant diode laser a risk factor?

AIMS: To evaluate rates of vitreous relapse among retinoblastoma patients treated with primary chemotherapy and assess diode laser as a potential risk factor for relapse. METHODS: Retrospective review of all patients treated with primary chemotherapy at a large ocular oncology centre. Eyes that developed vitreous relapse were coded with regard to Reese-Ellsworth Group, laterality, time to relapse, type of relapse (vitreous base or non-vitreous base relapse), treatments used (including adjuvant diode laser), and ocular preservation. Individual tumour foci treated with laser hyperthermia were also coded for laser parameters including power settings, number of treatments, and concomitant administration of systemic chemotherapy (chemothermotherapy). RESULTS: 15 of 106 eyes (14.15%) developed vitreous relapse over a 6 year period. Mean time to relapse was 7.2 months after chemotherapy was completed. Five cases (33%) were of the vitreous base variety. Ocular salvage was attempted in 11 cases using a variety of methods; one patient was lost to follow up. Six of the remaining 10 eyes (60%) were salvaged. Eight of 38 eyes (21%) treated with systemic chemotherapy and laser hyperthermia developed vitreous relapse compared with seven of 68 eyes (10%) treated with primary chemotherapy alone (p<0.005). Laser settings, number of hyperthermia treatments, and the concomitant use of systemic chemotherapy (chemothermotherapy) were not associated with higher rates of vitreous relapse. CONCLUSION: Nearly one in seven eyes with retinoblastoma treated with primary chemotherapy may develop vitreous relapse. The administration of diode laser hyperthermia appears to increase this risk. Despite additional therapy a number of these eyes succumb to enucleation.

Hepatoblastoma and familial adenomatous polyposis.

Eleven children have been identified as having hepatoblastoma and a family history of adenomatous polyposis, and 14 additional instances of this association have been collected from the literature. Among the 11 survivors of hepatoblastoma in the combined series, adenomatous lesions have been sought in seven and detected in six patients at ages 7 to 25 years. Five of these patients also have congenital hypertrophy of the retinal pigment epithelium, a marker for carriers of the polyposis gene. These findings strengthen the association between hepatoblastoma and familial adenomatous polyposis and have led to the establishment of the Hepatoblastoma-Adenomatous Polyposis Registry.

Combining cyclosporin with chemotherapy controls intraocular retinoblastoma without requiring radiation.

Chemotherapy without radiation has not controlled most intraocular retinoblastoma, perhaps because of the common high expression of multidrug resistance P-glycoprotein that we found in retinoblastoma. Cyclosporin blocks P-glycoprotein-induced efflux of vincristine and teniposide in vitro, and possibly modulates responses to carboplatin. To avoid eye irradiation in bilateral retinoblastoma patients with RB1 germline mutations, which incurs a high second malignancy rate, we added cyclosporin A to a vincristine-teniposide-carboplatin protocol and consolidated chemotherapy responses with focal therapy. We scored patients requiring irradiation, enucleation, or focal ablation of central vision as failures. In 21 study patients, the overall relapse-free rate at a median follow-up of 3.3 years was 76%, with a rate of 92% for newly diagnosed and 50% for previously treated, relapsed retinoblastoma. Our results for the most unfavorable tumors with vitreous seeds (86% at 3.5 years) are better than published success rates of irradiation for similar tumors, or irradiation with the same chemotherapy without cyclosporin (45% at 2. 6 years). These results also exceeded our historic success rate with similar chemotherapy without cyclosporin, focal therapy, and/or radiation in 19 equivalently poor-risk patients (relapse-free rate 37% at a median follow-up of 5.6 years, P = 0.032), 16 of whom were previously untreated (relapse-free rate also 37%, P = 0.012). A better outcome occurred with higher cyclosporin blood levels and projected tissue exposure. Cyclosporin did not enhance the usual chemotoxicity. This clinical study suggests that cyclosporin improves the long-term response of retinoblastoma to chemotherapy, possibly by more than one mechanism.

Interaction of saddle girth construction and tension on respiratory mechanics and gas exchange during supramaximal treadmill exercise in horses.

OBJECTIVE: To determine the effect of girth construction and tension on respiratory mechanics and gas exchange during supramaximal treadmill exercise in horses. METHODS: Six healthy detrained Thoroughbred horses were exercised on a treadmill inclined at 10% at 110% VO2max. Horses were instrumented for respiratory mechanics and gas exchange studies, and data were recorded during incremental exercise tests. The animals were exercised for 2 min at 40% VO2max, and samples and measurements were collected at 1 min 45 sec. After 2 min, speed was increased to that estimated at 110% VO2max and data was collected at 45 sec, 90 sec and every 30 sec thereafter at this speed until the horses fatigued. Horses were run on three occasions with the same racing saddle and saddle packing but using two different girths, either an elastic girth (EG) or a standard canvas girth (SCG) which is nonelastic. A run with 5 kg tension applied to a standard canvas girth was the control for each horse, with additional runs at 15 kg using either the standard canvas girth or using the elastic girth. The runs were randomised and tensions applied were measured at end exhalation whilst at rest. RESULTS: Increasing girth tension was not associated with changes in respiratory mechanical or gas exchange properties. Although girths tightened to 15 kg tension had short run to fatigue times this was not found to be significantly different to girths set at 5 kg resting tension. Girth tensions declined at end exhalation in horses nearing fatigue. CONCLUSIONS: Loss in performance associated with high girth tensions is not due to alteration of respiratory mechanics. Loss in performance may be related to inspiratory muscles working at suboptimal lengths due to thoracic compression or compression of musculature around the chest. However, these changes are not reflected in altered respiratory mechanical or gas exchange properties measured during tidal breathing during supramaximal exercise. Other factors may hasten the onset of fatigue when horses exercise with tight girths and further studies are required to determine why excessively tight girths affect performance.