Phonon Thermal Transport in UO_{2} via Self-Consistent Perturbation Theory.

Computing thermal transport from first-principles in UO_{2} is complicated due to the challenges associated with Mott physics. Here, we use irreducible derivative approaches to compute the cubic and quartic phonon interactions in UO_{2} from first principles, and we perform enhanced thermal transport computations by evaluating the phonon Green's function via self-consistent diagrammatic perturbation theory. Our predicted phonon lifetimes at T=600 K agree well with our inelastic neutron scattering measurements across the entire Brillouin zone, and our thermal conductivity predictions agree well with previous measurements. Both the changes due to thermal expansion and self-consistent contributions are nontrivial at high temperatures, though the effects tend to cancel, and interband transitions yield a substantial contribution.

Assessing the Performance of Machine Learning Methods Trained on Public Health Observational Data: A Case Study From COVID-19.

From early in the coronavirus disease 2019 (COVID-19) pandemic, there was interest in using machine learning methods to predict COVID-19 infection status based on vocal audio signals, for example, cough recordings. However, early studies had limitations in terms of data collection and of how the performances of the proposed predictive models were assessed. This article describes how these limitations have been overcome in a study carried out by the Turing-RSS Health Data Laboratory and the UK Health Security Agency. As part of the study, the UK Health Security Agency collected a dataset of acoustic recordings, SARS-CoV-2 infection status and extensive study participant meta-data. This allowed us to rigorously assess state-of-the-art machine learning techniques to predict SARS-CoV-2 infection status based on vocal audio signals. The lessons learned from this project should inform future studies on statistical evaluation methods to assess the performance of machine learning techniques for public health tasks.

Thermal Energy Transport in Oxide Nuclear Fuel.

To efficiently capture the energy of the nuclear bond, advanced nuclear reactor concepts seek solid fuels that must withstand unprecedented temperature and radiation extremes. In these advanced fuels, thermal energy transport under irradiation is directly related to reactor performance as well as reactor safety. The science of thermal transport in nuclear fuel is a grand challenge as a result of both computational and experimental complexities. Here we provide a comprehensive review of thermal transport research on two actinide oxides: one currently in use in commercial nuclear reactors, uranium dioxide (UO2), and one advanced fuel candidate material, thorium dioxide (ThO2). In both materials, heat is carried by lattice waves or phonons. Crystalline defects caused by fission events effectively scatter phonons and lead to a degradation in fuel performance over time. Bolstered by new computational and experimental tools, researchers are now developing the foundational work necessary to accurately model and ultimately control thermal transport in advanced nuclear fuels. We begin by reviewing research aimed at understanding thermal transport in perfect single crystals. The absence of defects enables studies that focus on the fundamental aspects of phonon transport. Next, we review research that targets defect generation and evolution. Here the focus is on ion irradiation studies used as surrogates for damage caused by fission products. We end this review with a discussion of modeling and experimental efforts directed at predicting and validating mesoscale thermal transport in the presence of irradiation defects. While efforts in these research areas have been robust, challenging work remains in developing holistic tools to capture and predict thermal energy transport across widely varying environmental conditions.

Advances in actinide thin films: synthesis, properties, and future directions.

Actinide-based compounds exhibit unique physics due to the presence of 5f electrons, and serve in many cases as important technological materials. Targeted thin film synthesis of actinide materials has been successful in generating high-purity specimens in which to study individual physical phenomena. These films have enabled the study of the unique electron configuration, strong mass renormalization, and nuclear decay in actinide metals and compounds. The growth of these films, as well as their thermophysical, magnetic, and topological properties, have been studied in a range of chemistries, albeit far fewer than most classes of thin film systems. This relative scarcity is the result of limited source material availability and safety constraints associated with the handling of radioactive materials. Here, we review recent work on the synthesis and characterization of actinide-based thin films in detail, describing both synthesis methods and modeling techniques for these materials. We review reports on pyrometallurgical, solution-based, and vapor deposition methods. We highlight the current state-of-the-art in order to construct a path forward to higher quality actinide thin films and heterostructure devices.

Non-reversible tissue fixation retains extracellular vesicles for in situ imaging.

Extracellular vesicles (EVs) are secreted nanosized particles with many biological functions and pathological associations. The inability to image EVs in fixed tissues has been a major limitation to understanding their role in healthy and diseased tissue microenvironments. Here, we show that crosslinking mammalian tissues with formaldehyde results in significant EV loss, which can be prevented by additional fixation with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) for visualization of EVs in a range of normal and cancer tissues.

Inferring relative dose-dependent color center populations in proton irradiated thoria single crystals using optical spectroscopy.

We have utilized photoluminescence spectroscopy and optical ellipsometry to characterize the dose-dependence of the photoluminescence emission intensity and changes in optical absorption of thoria single crystals subject to irradiation with energetic protons at room- and elevated-temperatures. The photoluminescence peaks and the optical absorption bands are attributed to creation of new electronic states emerging from defects resulting from displacement damage. These bands are most likely associated with electrons trapped at the oxygen vacancy sites similar to color centers formed in other irradiated oxides and halides. Our experimental observations are supported by a standard density functional theory calculation of the electronic structure in pristine and oxygen vacancy-bearing thoria crystals. The dose-dependence of the intensity of the photoluminescence peaks is used to parameterize a rate theory model that estimates the concentration of color centers in the irradiated crystals. This parameterization provides optimized migration barrier parameters for oxygen interstitials and vacancies that simultaneously capture the optical response of the crystals irradiated at room- and elevated-temperature. These optical spectroscopy techniques offer a promising pathway to characterize the population of color centers formed at the sites of oxygen anion vacancies, particularly in irradiated nuclear fuels, where atomic-level defects cannot be readily imaged using electron microscopy. When combined with other direct and indirect characterization tools, our approach can provide new insight into defect formation and accumulation in energy materials over single atomic to extended length scales.

Assessing the infiltration of immune cells in the upper trachea mucosa after infectious laryngotracheitis virus (ILTV) vaccination and challenge.

The types of immune cells that populate the trachea after ILTV vaccination and infection have not been assessed. The objective of this study was to quantify CD4+, CD8α+, CD8ß+, TCRγδ+, and MRC1LB+ cells that infiltrate the trachea after vaccination with chicken embryo origin (CEO), tissue culture origin (TCO), and recombinant herpesvirus of turkey-laryngotracheitis (rHVT-LT) vaccines, and after challenge of vaccinated and non-vaccinated chickens with a virulent ILTV strain. Eye-drop vaccination with CEO, or TCO, or in ovo vaccination with rHVT-LT did not alter the number of CD4+, CD8α+, CD8ß+, TCRγδ+, and MRC1LB+ cells in the trachea. After challenge, the CEO vaccinated group of chickens showed swift clearance of the challenge virus, the mucosa epithelium of the trachea remained intact, and a limited number of CD4+, CD8α+, and CD8ß+ cells were detected in the upper trachea mucosa. The TCO and rHVT-LT vaccinated groups of chickens showed narrow viral clearance with moderate disruption of the trachea epithelial integrity, and a significant increase in CD4+, CD8α+, CD8ß+, and TCRγδ+ cells infiltrated the upper trachea mucosa. Non-vaccinated challenged chickens showed high levels of viral replication, the epithelial organization of the upper trachea mucosa was heavily disrupted, and the predominant infiltrates were CD4+, TCRγδ+, and MRC1LB+ cells. Hence, the very robust protection provided by CEO vaccination was characterized by minimal immune cell infiltration to the trachea mucosa. In contrast, partial protection induced by the TCO and rHVT-LT vaccines requires a prolonged period of T cell expansion to overcome the established infection in the trachea mucosa.

Collagenase Clostridium Histolyticum-aaes for the Treatment of Cellulite in Women: Results From Two Phase 3 Randomized, Placebo-Controlled Trials.

BACKGROUND: Fibrous septae play a role in contour alterations associated with cellulite. OBJECTIVE: To assess collagenase clostridium histolyticum-aaes (CCH) for the treatment of cellulite. MATERIALS AND METHODS: Two identically designed phase 3, double-blind, randomized studies (RELEASE-1 and RELEASE-2) were conducted. Adult women with moderate/severe cellulite (rating 3-4 on the Patient Reported Photonumeric Cellulite Severity Scale [PR-PCSS] and Clinician Reported PCSS [CR-PCSS]) on the buttocks received up to 3 treatment sessions of subcutaneous CCH 0.84 mg or placebo per treatment area. Composite response (≥2-level or ≥1-level improvement from baseline in both PR-PCSS and CR-PCSS) was determined at Day 71. RESULTS: Eight hundred forty-three women received ≥1 injection (CCH vs placebo: RELEASE-1, n = 210 vs n = 213; RELEASE-2, n = 214 vs n = 206). Greater percentages of CCH-treated women were ≥2-level composite responders versus placebo in RELEASE-1 (7.6% vs 1.9%; p = .006) and RELEASE-2 (5.6% vs 0.5%; p = .002) and ≥1-level composite responders in RELEASE-1 (37.1% vs 17.8%; p < .001) and RELEASE-2 (41.6% vs 11.2%; p < .001). Most adverse events (AEs) in the CCH group were injection site related; few CCH-treated women discontinued because of an AE (≤4.3%). CONCLUSION: Collagenase clostridium histolyticum-aaes significantly improved cellulite appearance and was generally well tolerated.

Antisperm antibodies and sperm function in bulls undergoing scrotal insulation.

Bovine antisperm antibodies (ASAs) have been associated with teratospermia and asthenospermia. It was hypothesized here that scrotal insulation induces the formation of ASAs and deterioration of sperm function. Scrotal insulation bags were placed in 10 bulls for 8 days. Semen was collected on days -29, -22 and -2, twice weekly from days 5 to 54, and thereafter weekly until day 96 (day 0 = first day of scrotal insulation). On each collection day, scrotal circumference, sperm motility, morphology, membrane integrity, acrosome integrity, apoptosis, lipid peroxidation, mitochondrial membrane potential, ASA binding and DNA integrity were evaluated. The percentage of IgG- and IgA-bound sperm increased between days 12 and 96 (P < 0.0001), in association with poor motility (days 19-30, P < 0.005) and morphology (days 8-40, P < 0.0001). Mean scrotal circumference decreased between days 15 and 75 (P < 0.0001). There was also a deterioration in sperm membrane integrity (days 19-40, P < 0.0001), acrosome integrity (days 26-89, P < 0.0001), lipid peroxidation (days 5-12, P < 0.0001), and mitochondrial membrane potential (days 12-96, P = 0.001). In contrast, a decrease in apoptotic cells (days 37-83, P = 0.0002) and lipid peroxidation (days 19-96, P < 0.0001) was noticed. Most bulls recovered normospermia by day 96. However, the persistence of ASAs, acrosomal damage and dysfunctional mitochondria suggest a long term effect of scrotal insulation on sperm function and the homeostasis of the reproductive immune system.

Development and Validation Clinician and Patient Reported Photonumeric Scales to Assess Buttocks Cellulite Severity.

BACKGROUND: The Clinician Reported Photonumeric Cellulite Severity Scale (CR-PCSS) and Patient Reported PCSS (PR-PCSS) are newly developed tools for assessing cellulite severity. OBJECTIVE: To report on the reliability, validity, and ability to detect a change in cellulite severity on the buttocks of adult women with the CR-PCSS and PR-PCSS. MATERIALS AND METHODS: Content validity of both scales was established through concept elicitation and cognitive interviews. Test-retest reliability was evaluated, and intra-rater (both scales) and inter-rater (CR-PCSS only) reliability were estimated using intraclass correlation coefficients (ICCs) for agreement and consistency. Ability to detect a change was determined using the Subject-Global Aesthetic Improvement Scale (GAIS) or Investigator-GAIS as anchors. RESULTS: For the CR-PCSS (n = 6) at baseline and Day 2, the mean interrater ICCs were ≥0.70 and mean intrarater ICCs (95% confidence interval [CI]) were ≥0.81 (0.72-0.90) for both buttocks. For the PR-PCSS (n = 99) at baseline and Day 14, the mean test-retest reliability ICCs (95% CI) were ≥0.86 (0.79-0.91) for both buttocks. A clinically meaningful change was 1.0 point on the PR-PCSS and 1.0 on the CR-PCSS. CONCLUSION: The CR-PCSS and PR-PCSS reliably assess cellulite severity of the buttocks and can detect a clinically meaningful change after treatment for cellulite.

The comparative efficacy of disinfectant wipes on common-use computer keyboards in a veterinary teaching hospital.

The efficacies of 3 disinfectant wipes at reducing bacterial contamination on keyboards in a veterinary teaching hospital were studied. Thirty common-use keyboards were randomized into "dirty" and "clean" halves. Cultures were obtained from the "dirty" halves. The "clean" halves were disinfected with a randomly assigned wipe [peroxygen (AHP)-, alcohol-, quaternary ammonium (QAC)-based] or untreated (NT) and cultured. Colony-forming units (CFU) were enumerated after 48 hours. Mean reduction in CFU was 91.5%, 65.3%, 94.9%, and 78.8% for the AHP, alcohol, QAC, and NT groups, respectively. There was a significant reduction in CFUs between the dirty and clean keyboard halves within each group but no statistically significant differences were noted between groups. The reduction in CFUs in the NT group was attributed to the mechanical action of wiping the keyboard surface for culture. The use of disinfectant wipes reduced CFUs on keyboards and may be a useful component of veterinary infection control programs.

Efficacité comparative de lingettes désinfectantes sur des claviers d'ordinateurs en usage commun dans un hôpital d'enseignement vétérinaire. L'efficacité de trois lingettes désinfectantes à réduire la contamination bactérienne sur des claviers dans un hôpital d'enseignement vétérinaire fut étudiée. Trente claviers en usage commun furent séparés de manière aléatoire en moitié « sale ¼ et « propre ¼. Des cultures furent obtenues de la moitié « sale ¼. La moitié « propre ¼ fut désinfectée avec une lingette assignée de manière aléatoire [à base de peroxygène (AHP), alcool, ou ammonium quaternaire (QAC)] ou non traitée (NT) et échantillonnée pour culture. Le nombre d'unités formatrices de colonies (CFU) fut énuméré après 48 heures. La réduction moyenne de CFU était de 91,5 %, 65,3 %, 94,9 %, et 78,8 % pour les groupes AHP, alcool, QAC, et NT, respectivement. Il y avait une réduction significative dans les CFUs entre les claviers des moitiés sale et propre dans chaque groupe mais aucune différence statistiquement significative ne fut notée entre les groupes. La réduction en CFU dans le groupe NT fut attribuée à l'action mécanique de frottage de la surface des claviers. L'utilisation de lingettes désinfectantes a réduit le nombre d'UFC sur les claviers et pourrait être une composante utile des programmes de surveillance des infections vétérinaires.(Traduit par Dr Serge Messier).

Evidence for an unknown agent antigenically related to the hepatitis E virus in dairy cows in the United States.

Genotypes 3 and 4 hepatitis E virus (HEV) strains within the species Orthohepevirus A in the family Hepeviridae are zoonotic. Recently, a genotype 4 HEV was reportedly detected in fecal samples of cows, although independent confirmation is lacking. In this study, we first tested serum samples from 983 cows in different regions in the United States for the presence of immunoglobulin G (IgG) anti-HEV and found that 20.4% of cows were seropositive. The highest seroprevalence rate (68.4%) was from a herd in Georgia. In an attempt to genetically identify HEV in cattle, a prospective study was conducted in a known seropositive dairy herd by monitoring 10 newborn calves from birth to 6 months of age for evidence of HEV infection. At least 3 of the 10 calves seroconverted to IgG anti-HEV, and importantly the antibodies presented neutralized genotype 3 human HEV, thus, indicating the specificity of IgG anti-HEV in the cattle. However, our extensive attempts to identify HEV-related sequences in cattle using broad-spectrum reverse transcription-polymerase chain reaction assays and MiSeq deep-sequencing technology failed. The results suggest the existence of an agent antigenically related to HEV in cattle, although, contrary to published reports, we showed that the IgG recognizing HEV in cattle was not caused by HEV infection.

Collagenase Clostridium Histolyticum for the Treatment of Edematous Fibrosclerotic Panniculopathy (Cellulite): A Randomized Trial.

BACKGROUND: Edematous fibrosclerotic panniculopathy (EFP; cellulite) is associated with thickening and contraction of collagen-rich subdermal septae. Collagenase clostridium histolyticum (CCH) may disrupt collagen-rich septae. OBJECTIVE: To evaluate the safety and efficacy of CCH for treatment of EFP. MATERIALS AND METHODS: In a randomized, double-blind study, women with moderate or severe EFP of the buttocks or posterolateral thighs (i.e., Clinician Reported Photonumeric Cellulite Severity Scale [CR-PCSS] and Patient Reported Photonumeric Cellulite Severity Scale [PR-PCSS] ratings of 3 to 4, and Hexsel Cellulite Severity Scale score ≤13) received up to 3 treatment sessions (Days 1, 22, and 43) of subcutaneous CCH 0.84 mg or placebo injections. End points included the percentage of 2-level and 1-level composite responders (i.e., had ≥2-level or ≥1-level improvement in CR-PCSS and PR-PCSS) at Day 71. RESULTS: Three hundred seventy-five women (mean age, 46.5 years; 86.4% white) were randomly assigned to CCH (n = 189) or placebo (n = 186). At Day 71, the percentages of 2-level and 1-level composite responders were greater with CCH (10.6% and 44.6%, respectively) versus placebo (1.6% and 17.9%; p < .001 for both). The most common adverse events were injection-site related. CONCLUSION: CCH significantly improved EFP appearance versus placebo; further evaluation of CCH for EFP (cellulite) is warranted.

Virome of US bovine calf serum.

Using viral metagenomics we analyzed four bovine serum pools assembled from 715 calves in the United States. Two parvoviruses, bovine parvovirus 2 (BPV2) and a previously uncharacterized parvovirus designated as bosavirus (BosaV), were detected in 3 and 4 pools respectively and their complete coding sequences generated. Based on NS1 protein identity, bosavirus qualifies as a member of a new species in the copiparvovirus genus. Also detected were low number of reads matching ungulate tetraparvovirus 2, bovine hepacivirus, and several papillomaviruses. This study further characterizes the diversity of viruses in calf serum with the potential to infect fetuses and through fetal bovine serum contaminate cell cultures.

Frequency-resolved Raman for transient thermal probing and thermal diffusivity measurement.

A new transient Raman thermal probing technique, frequency-resolved Raman (FR-Raman), is developed for probing the transient thermal response of materials and measuring their thermal diffusivity. The FR-Raman uses an amplitude-modulated square-wave laser for simultaneous material heating and Raman excitation. The evolution profile of Raman properties: intensity, Raman wavenumber, and emission, against frequency are reconstructed and used for fitting to determine the thermal diffusivity. A microscale silicon (Si) cantilever is used to investigate the capacity of this new technique. The thermal diffusivity is determined as 9.57×10-5 m2/s, 11.00×10-5 m2/s, and 9.02×10-5 m2/s via fitting Raman intensity, wavenumber, and total Raman emission, respectively. The results agree well with literature data. The FR-Raman provides a novel way for transient thermal probing with very high temporal resolution and micrometer-scale spatial resolution.

Survey of Intraoperative Bacterial Contamination in Dogs Undergoing Elective Orthopedic Surgery.

OBJECTIVE: To investigate the frequency, source, and risk factors of intraoperative (IO) surgeon and patient bacterial contamination during clean orthopedic surgeries, and to investigate the relationship between IO contamination and surgical site infection (SSI) in dogs. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Client-owned dogs undergoing stifle surgery (n = 100). METHODS: IO cultures were taken in each case from surgical foot wrap, peri-incisional skin, surgical gloves, and the surgical team's hands. The environment (operating room [OR] lights, computers, scrub sink faucet, anesthesia gurney, and radiology table) was sampled every 5 months. Bacteria were identified and the contamination of each case was categorized. All gloves from the surgical team were collected and tested for perforations using a water infusion test. Cases were followed for at least 8 weeks to determine the presence or absence of SSI. Perioperative variables were evaluated for association with IO contamination and SSI. RESULTS: Bacterial isolates were yielded from 81% of procedures from 1 or more sources; 58% had positive hand cultures, 46% had positive glove cultures, 23% had positive patient skin cultures, and 12% had positive foot wrap cultures. Staphylococcus spp. was the most commonly recovered bacteria. There was no apparent association between IO contamination and SSI. The highest level of environmental contamination was associated with the scrub sink faucet, followed by the radiology table, anesthesia gurney, and OR computers. The IO glove perforation rate was 18%. CONCLUSION: Clean orthopedic procedures commonly had clinically insignificant bacterial contamination. In our study, bacteria responsible for SSI did not appear to colonize the patient in the OR.

Development of time-domain differential Raman for transient thermal probing of materials.

A novel transient thermal characterization technology is developed based on the principles of transient optical heating and Raman probing: time-domain differential Raman. It employs a square-wave modulated laser of varying duty cycle to realize controlled heating and transient thermal probing. Very well defined extension of the heating time in each measurement changes the temperature evolution profile and the probed temperature field at µs resolution. Using this new technique, the transient thermal response of a tipless Si cantilever is investigated along the length direction. A physical model is developed to reconstruct the Raman spectrum considering the temperature evolution, while taking into account the temperature dependence of the Raman emission. By fitting the variation of the normalized Raman peak intensity, wavenumber, and peak area against the heating time, the thermal diffusivity is determined as 9.17 × 10(-5), 8.14 × 10(-5), and 9.51 × 10(-5) m(2)/s. These results agree well with the reference value of 8.66 × 10(-5) m(2)/s considering the 10% fitting uncertainty. The time-domain differential Raman provides a novel way to introduce transient thermal excitation of materials, probe the thermal response, and measure the thermal diffusivity, all with high accuracy.

Collagenase Clostridium Histolyticum for the Treatment of Dupuytren Disease: A Delphi-Based Consensus Study.

Purpose: The aim of this study was to establish the consensus recommendations among hand surgeons who were experts in the use of collagenase clostridium histolyticum (CCH) on the appropriate treatment of Dupuytren disease in well-defined patient populations with varying degrees of disease severity and functional impairment. Methods: A three-round, blinded, modified Delphi process examined panelists' approaches to CCH treatment of metacarpophalangeal (MP) or proximal interphalangeal (PIP) joint contractures involving one or two fingers with varying degrees of severity. Clinical scenarios related to poor-quality skin, postfasciectomy scarring, boutonnière deformity, closed capsulotomy, and blood thinner use were also presented for panelist consideration. Panelists provided responses to clinical scenarios using a 5-point Likert scale or a yes/no response. Consensus was defined as ≥66.7% panelist agreement or disagreement. Results: Twenty panelists completed round 1; 19 of the 20 panelists completed rounds 2 and 3. Panelists achieved a high level of consensus for using CCH for the treatment of patients with palpable cords and varying severity contractures representing one- or two-finger MP joint contractures, most one- or two-finger PIP joint contractures, and most combined MP and PIP joint contractures. Consensus for the treatment of PIP joint contractures was mostly achieved, but clinical scenarios related to recurrent PIP contracture with poor-quality skin and/or significant postfasciectomy scarring, boutonnière deformity, PIP contractures >70°, closed capsulotomy, and blood thinner use were modified, and then most (95.3%) statements reached consensus for agreement in round 2. In round 3, open-ended responses indicated that panelists considered CCH appropriate for most patients with Dupuytren disease. Conclusions: Consensus-based findings among expert hand surgeons with substantial CCH experience indicated that CCH has a wide-ranging application for the treatment of Dupuytren disease in patients with varying degrees of disease severity and functional impairment. Type of study/level of evidence: Therapeutic V.

Analytical and clinical validation of diagnostic tests for the detection of leucospermia in beef bulls.

The objectives of this study were to validate diagnostic tests to detect polymorphonuclear cells (PMNs) in bull semen, and to determine the prevalence of leucospermia in beef bulls with varying semen quality. We hypothesized that all tests have comparable diagnostic value, and that leucospermia is more prevalent in unsatisfactory breeders in association with poor semen quality. For the analytical validation, one ejaculate was obtained from five bulls. Aliquots of 50 × 106 purified sperm were incubated in triplicate with six concentrations of purified bovine PMNs: 1) no PMNs, 2) 0.25 × 106 PMN/ml, 3) 0.5 × 106 PMN/ml, 4) 2.5 × 106 PMN/ml, 5) 5 × 106 PMN/ml, 6) 10 × 106 PMN/ml. The PMNs were quantified using a hemacytometer, cytology, a leucocyte esterase dipstick test (LEDT), a peroxidase test, and CD45 immunolabeling. The number of leucocytes detected with the LEDT differed among treatments (P < 0.0001). The quantitative tests detected differences with the control treatment at a PMN concentration of ≥2.5 × 106 PMN/ml (P < 0.0001). Sperm motion parameters after 4 h of incubation at 38 °C were lower in samples with ≥5 × 106 PMN/ml (P < 0.05). For the clinical validation, semen samples from 305 beef bulls were evaluated. Unsatisfactory breeders (n = 83) had more CD45-positive cells (P = 0.016) and positive LEDT results (P = 0.008) than satisfactory breeders (n = 222). With CD45 immunostaining as the gold standard, the hemacytometer count had the highest clinical sensitivity (64.3 %) but the lowest specificity (73.3 %). A higher specificity was obtained with the peroxidase test (95.1 %) or semen cytology (98.8 %). In conclusion, the presence of ≥5 × 106 PMN/ml was associated with decreased semen quality in beef bulls. The hemacytometer count was the most sensitive bull-side test. But due to the low specificity, positive hemacytometer counts should be confirmed with the identification of peroxidase-positive cells or morphological identification of leucocytes on semen cytology. The CD45 immunostaining is the gold standard for the diagnosis of leucospermia in bulls.