Discrete Pools of Oligomeric Amyloid-ß Track with Spatial Learning Deficits in a Mouse Model of Alzheimer Amyloidosis.

Despite increasing appreciation that oligomeric amyloid-ß (Aß) may contribute to cognitive decline of Alzheimer disease, defining the most critical forms has been thwarted by the changeable nature of these aggregates and the varying methods used for detection. Herein, using a broad approach, we quantified Aß oligomers during the evolution of cognitive deficits in an aggressive model of Aß amyloidosis. Amyloid precursor protein/tetracycline transactivator mice underwent behavioral testing at 3, 6, 9, and 12 months of age to evaluate spatial learning and memory, followed by histologic assessment of amyloid burden and biochemical characterization of oligomeric Aß species. Transgenic mice displayed progressive impairments in acquisition and immediate recall of the trained platform location. Biochemical analysis of cortical extracts from behaviorally tested mice revealed distinct age-dependent patterns of accumulation in multiple oligomeric species. Dot blot analysis demonstrated that nonfibrillar Aß oligomers were highly soluble and extracted into a fraction enriched for extracellular proteins, whereas prefibrillar species required high-detergent conditions to retrieve, consistent with membrane localization. Low-detergent extracts tested by 82E1 enzyme-linked immunosorbent assay confirmed the presence of bona fide Aß oligomers, whereas immunoprecipitation-Western blotting using high-detergent extracts revealed a variety of SDS-stable low-n species. These findings show that different Aß oligomers vary in solubility, consistent with distinct localization, and identify nonfibrillar Aß oligomer-positive aggregates as tracking most closely with cognitive decline in this model.

Development of the Initial Surveys for the All of Us Research Program.

BACKGROUND: The All of Us Research Program is building a national longitudinal cohort and collecting data from multiple information sources (e.g., biospecimens, electronic health records, and mobile/wearable technologies) to advance precision medicine. Participant-provided information, collected via surveys, will complement and augment these information sources. We report the process used to develop and refine the initial three surveys for this program. METHODS: The All of Us survey development process included: (1) prioritization of domains for scientific needs, (2) examination of existing validated instruments, (3) content creation, (4) evaluation and refinement via cognitive interviews and online testing, (5) content review by key stakeholders, and (6) launch in the All of Us electronic participant portal. All content was translated into Spanish. RESULTS: We conducted cognitive interviews in English and Spanish with 169 participants, and 573 individuals completed online testing. Feedback led to over 40 item content changes. Lessons learned included: (1) validated survey instruments performed well in diverse populations reflective of All of Us; (2) parallel evaluation of multiple languages can ensure optimal survey deployment; (3) recruitment challenges in diverse populations required multiple strategies; and (4) key stakeholders improved integration of surveys into larger Program context. CONCLUSIONS: This efficient, iterative process led to successful testing, refinement, and launch of three All of Us surveys. Reuse of All of Us surveys, available at http://researchallofus.org, may facilitate large consortia targeting diverse populations in English and Spanish to capture participant-provided information to supplement other data, such as genetic, physical measurements, or data from electronic health records.

Investigation of chemical composition of meat using spatially off-set Raman spectroscopy.

Spatially off-set Raman spectroscopy (SORS) offers non-invasive chemical characterisation of the sub-surface of various biological tissues as it permits the assessment of diffusely scattering samples at depths of several orders of magnitude deeper than conventional Raman spectroscopy. Chemicals such as glycogen, glucose, lactate and cortisol are predictors of meat quality, however detection of these chemicals is limited to the surface of meat using conventional Raman spectroscopy as their concentration is higher within the tissue. Here, we have used SORS to detect spectral bands for glycogen, lactate, glucose and cortisol beneath the surface of meat tissue by spiking. To our knowledge, this is the first report on this method for potential application in meat quality analysis. We further validate our SORS spectral results using chemometric analysis to determine chemical-specific spectral characteristics suitable for chemical identification. The chemometric analysis clearly shows distinction of spiked metabolites into four distinct groups, even for such chemically similar compounds as glucose, glycogen and lactate.

Timing of gestational exposure to Zika virus is associated with postnatal growth restriction in a murine model.

BACKGROUND: Vertical transmission of Zika virus leads to infection of neuroprogenitor cells and destruction of brain parenchyma. Recent evidence suggests that the timing of infection as well as host factors may affect vertical transmission. As a result, congenital Zika virus infection may only become clinically apparent in the postnatal period. OBJECTIVE: We sought to develop an outbred mouse model of Zika virus vertical transmission to determine if the timing of gestational Zika virus exposure yields phenotypic differences at birth and through adolescence. We hypothesized that later gestational inoculations would only become apparent in adolescence. STUDY DESIGN: To better recapitulate human exposures, timed pregnant Swiss-Webster dams (n = 15) were subcutaneously inoculated with 1 × 104 plaque-forming units of first passage contemporary Zika virus HN16 strain or a mock injection on embryonic day 4, 8, or 12 with bioactive antiinterferon alpha receptor antibody administered in days preceding and proceeding inoculation. The antibody was given to prevent the robust type I interferon signaling cascade that make mice inherently resistant to Zika virus infection. At birth and adolescence (6 weeks of age) offspring were assessed for growth, brain weight, and biparietal head diameters, and Zika virus viral levels by reverse transcription-polymerase chain reaction or in situ hybridization. RESULTS: Pups of Zika virus-infected dams infected at embryonic days 4 and 8 but not 12 were growth restricted (P < .003). Brain weights were significantly smaller at birth (P = .01) for embryonic day 8 Zika virus-exposed offspring. At 6 weeks of age, biparietal diameters were smaller for all Zika virus-exposed males and females (P < .05), with embryonic day 8-exposed males smallest by biparietal diameter and growth-restriction measurements (weight >2 SD, P = .0007). All pups and adolescent mice were assessed for Zika virus infection by reverse transcription-polymerase chain reaction. Analysis of all underweight pups reveled 1 to be positive for neuronal Zika virus infection by in situ hybridization, while a second moribund animal was diffusely positive at 8 days of age by Zika virus infectivity throughout the brain, kidneys, and intestine. CONCLUSION: These findings demonstrate that postnatal effects of infection occurring at single time points continue to be detrimental to offspring in the postnatal period in a subset of littermates and subject to a window of gestational susceptibility coinciding with placentation. This model recapitulates frequently encountered clinical scenarios in nonendemic regions, including the majority of the United States, where travel-related exposure occurs in short and well-defined windows of gestation. Our low rate of infection and relatively rare evidence of congenital Zika syndrome parallels human population-based data.

Genetic modulation of soluble Aß rescues cognitive and synaptic impairment in a mouse model of Alzheimer's disease.

An unresolved debate in Alzheimer's disease (AD) is whether amyloid plaques are pathogenic, causing overt physical disruption of neural circuits, or protective, sequestering soluble forms of amyloid-ß (Aß) that initiate synaptic damage and cognitive decline. Few animal models of AD have been capable of isolating the relative contribution made by soluble and insoluble forms of Aß to the behavioral symptoms and biochemical consequences of the disease. Here we use a controllable transgenic mouse model expressing a mutant form of amyloid precursor protein (APP) to distinguish the impact of soluble Aß from that of deposited amyloid on cognitive function and synaptic structure. Rapid inhibition of transgenic APP modulated the production of Aß without affecting pre-existing amyloid deposits and restored cognitive performance to the level of healthy controls in Morris water maze, radial arm water maze, and fear conditioning. Selective reduction of Aß with a γ-secretase inhibitor provided similar improvement, suggesting that transgene suppression restored cognition, at least in part by lowering Aß. Cognitive improvement coincided with reduced levels of synaptotoxic Aß oligomers, greater synaptic density surrounding amyloid plaques, and increased expression of presynaptic and postsynaptic markers. Together these findings indicate that transient Aß species underlie much of the cognitive and synaptic deficits observed in this model and demonstrate that significant functional and structural recovery can be attained without removing deposited amyloid.

Prior experience with a pain stimulus as a predictor of placebo analgesia.

Placebo effects are important in pain reduction, but the effects are inconsistent. Prior experience with a pain stimulus may moderate placebo analgesia. The current study tests the effect of prior experience with a pain stimulus on placebo analgesia during a laboratory pain task. Healthy normotensive undergraduates (66 women, 68 men) who either did or did not report prior experience with pain from submerging a limb in cold water were enrolled. In the laboratory, an experimenter applied an inert, medicinal-smelling cream to participants' non-dominant hand. Participants randomized to the no-expectation group were told that the cream was a hand cleanser. Participants randomized to the placebo expectation group were told that the cream would reduce the pain associated with the cold pressor task. Participants then completed the cold pressor task and reported their pain on the short form of the McGill Pain Questionnaire. Analysis of variance revealed a main effect of expectation (p < .05), such that participants in the placebo expectation group reported less pain. An interaction was also found between expectation and prior experience (p < .05), such that participants with prior experience with pain from cold water immersion showed no difference in pain reports between expectation groups. In a pain context, prior experience with the pain stimulus may prevent a placebo expectation from reducing the experience of pain.

Comparing the Maryland Comprehensive Cancer Control Plan With Federal Cancer Prevention and Control Recommendations.

INTRODUCTION: Since the introduction of the Affordable Care Act (ACA) in 2012, 11 million more Americans now have access to preventive services via health care coverage. Several prevention-related recommendations issued by the US Preventive Services Task Force (USPSTF), Centers for Disease Control and Prevention (CDC), and Advisory Committee on Immunization Practices (ACIP) are covered under the ACA. State cancer plans often provide prevention strategies, but whether these strategies correspond to federal evidence-based recommendations is unclear. The objective of this article is to assess whether federal evidence-based recommendations, including those covered under the ACA, are included in the Maryland Comprehensive Cancer Control Plan (MCCCP). METHODS: A total of 19 federal recommendations pertaining to cancer prevention and control were identified. Inclusion of federal cancer-related recommendations by USPSTF, CDC, and ACIP in the MCCCP's goals, objectives, and strategies was examined. RESULTS: Nine of the federal recommendations were issued after the MCCCP's publication. MCCCP recommendations corresponded completely with 4 federal recommendations and corresponded only partially with 3. Reasons for partial correspondence included specification of less restrictive at-risk populations or different intervention implementers. Three federal recommendations were not mentioned in the MCCCP's goals, objectives, and strategies. CONCLUSION: Many cancer-related federal recommendations were released after the MCCCP's publication and therefore do not appear in the most current version. We recommend that the results of this analysis be considered in the update of the MCCCP. Our findings underscore the need for a periodic scan for changes to federal recommendations and for adjusting state policies and programs to correspond with federal recommendations, as appropriate for Marylanders.

Impairments in experience-dependent scaling and stability of hippocampal place fields limit spatial learning in a mouse model of Alzheimer's disease.

Impaired spatial memory characterizes many mouse models for Alzheimer's disease, but we understand little about how this trait arises. Here, we use a transgenic model of amyloidosis to examine the relationship between behavioral performance in tests of spatial navigation and the function of hippocampal place cells. We find that amyloid precursor protein (APP) mice require considerably more training than controls to reach the same level of performance in a water maze task, and recall the trained location less well 24 h later. At a single cell level, place fields from control mice become more stable and spatially restricted with repeated exposure to a new environment, while those in APP mice improve less over time, ultimately producing a spatial code of lower resolution, accuracy, and reliability than controls. The limited refinement of place fields in APP mice likely contributes to their delayed water maze acquisition, and provides evidence for circuit dysfunction underlying cognitive impairment.

Continued development of a tool to measure intramuscular fat of Australian lamb carcases in commercial situations.

Despite the importance of intramuscular fat (IMF) to eating quality, as yet no methodology has been widely adopted by the whole of industry in Australia to measure it routinely. Thus, a study was conducted to investigate the potential for a Near Infra-Red (NIR) device to predict the IMF content of the loin from spectra collected on the topside which is externally located on a hanging carcase and therefore easily accessible. To this end, NIR spectra were collected from topsides (m. semimembranosus) of 258 lamb carcases over 5 data collections and a sample of muscle was collected from the loin and the topside for IMF determination using a wet chemistry method. Subsequent Partial Least Square (PLS) models suggested the ability to predict the absolute IMF content of loins was poor (R2 = 0.28, RMSE = 1.26), yet there was a moderate ability to predict the IMF content of the topside (R2 = 0.56, RMSE = 0.82). Partial Least Square Discrimination Analysis (PLS-DA) models to classify cuts based on the IMF eating quality threshold of 4.5% yielded better predictive outcomes with accuracies of 66.7% and 76.7% for loin and topside respectively. However, further research to assess the relationship between the IMF of the loin and topside and reduce the impact of differences in overall absorbance between data collections will improve predictive outcomes.

Validation of Raman spectroscopic models to verify the origin of Australian beef grown under different production systems.

Verification of beef production systems and authentication of origin is becoming increasingly important as consumers base purchase decisions on a greater number of perceived values including the healthiness and environmental impact of products. Previously Raman spectroscopy has been explored as a tool to classify carcases from grass and grain fed cattle. Thus, the aim of the current study was to validate Partial Least Squares Discriminant Analysis (PLS-DA) models created using independent samples from carcases sampled from northern and southern Australian production systems in 2019, 2020 and 2021. Validation of the robustness of discrimination models was undertaken using spectral measures of fat from 585 carcases which were measured in 2022 using a Raman handheld device with a sample excised for fatty acid analysis. PLS-DA models were constructed and then employed to classify samples as either grass or grain fed in a two-class model. Overall, predictions were high with accuracies of up to 95.7% however, variation in the predictive ability was noted with models created for southern cattle yielding an accuracy of 73.2%. While some variation in fatty acids and therefore models can be attributed to differences in genetics, management and diet, the impact of duration of feeding is currently unknown and thus further work is warranted.

The liver connexin32 interactome is a novel plasma membrane-mitochondrial signaling nexus.

Connexins are the structural subunits of gap junctions and act as protein platforms for signaling complexes. Little is known about tissue-specific connexin signaling nexuses, given significant challenges associated with affinity-purifying endogenous channel complexes to the level required for interaction analyses. Here, we used multiple subcellular fractionation techniques to isolate connexin32-enriched membrane microdomains from murine liver. We show, for the first time, that connexin32 localizes to both the plasma membrane and inner mitochondrial membrane of hepatocytes. Using a combination of immunoprecipitation-high throughput mass spectrometry, reciprocal co-IP, and subcellular fractionation methodologies, we report a novel interactome validated using null mutant controls. Eighteen connexin32 interacting proteins were identified. The majority represent resident mitochondrial proteins, a minority represent plasma membrane, endoplasmic reticulum, or cytoplasmic partners. In particular, connexin32 interacts with connexin26 and the mitochondrial protein, sideroflexin-1, at the plasma membrane. Connexin32 interaction enhances connexin26 stability. Converging bioinformatic, biochemical, and confocal analyses support a role for connexin32 in transiently tethering mitochondria to connexin32-enriched plasma membrane microdomains through interaction with proteins in the outer mitochondrial membrane, including sideroflexin-1. Complex formation increases the pool of sideroflexin-1 that is present at the plasma membrane. Together, these data identify a novel plasma membrane/mitochondrial signaling nexus in the connexin32 interactome.

Beliefs about expectations moderate the influence of expectations on pain perception.

BACKGROUND: Expectations congruently influence, or bias, pain perception. Recent social psychological research reveals that individuals differ in the extent to which they believe in expectation biases and that individuals who believe in expectation biases may adjust for this bias in their perceptions and reactions. That is, idiosyncratic beliefs about expectations can moderate the influence of expectations on experience. PURPOSE: Prior research has not examined whether idiosyncratic beliefs about expectations can alter the degree to which one's expectations influence pain perception. Using a laboratory pain stimulus, we examined the possibility that beliefs about expectation biases alter pain responses following both pain- and placebo-analgesic expectations. METHODS: Participants' beliefs about expectation biases were measured. Next, participants were randomly assigned to receive either a pain expectation or a placebo-analgesia expectation prior to a cold-pressor task. After the task, participants rated their pain. RESULTS: Beliefs about expectation biases significantly influenced pain reports. Specifically, pain reports were more influenced by provided expectations the less participants believed in expectation biases (i.e., pain expectations resulted in more pain than analgesia expectations). CONCLUSIONS: Beliefs about the expectation bias are an important and under-examined predictor of pain and placebo analgesia.

Preliminary investigation into the prediction of indicators of beef spoilage using Raman and Fourier transform infrared spectroscopy.

The objective of this study was to assess the potential to predict the microbial beef spoilage indicators by Raman and Fourier transform infrared (FT-IR) spectroscopies. Vacuum skin packaged (VSP) beef steaks were stored at 0 °C, 4 °C, 8 °C and under a dynamic temperature condition (0 °C âˆ¼ 4 °C âˆ¼ 8 °C, for 36 d). Total viable count (TVC) and total volatile basic nitrogen (TVB-N) were obtained during the storage period along with spectroscopic data. The Raman and FTIR spectra were baseline corrected, pre-processed using Savitzky-Golay smoothing and normalized. Subsequently partial least squares regression (PLSR) models of TVC and TVB-N were developed and evaluated. The root mean squared error (RMSE) ranged from 0.81 to1.59 (log CFU/g or mg/100 g) and the determination coefficient (R2) from 0.54 to 0.75. The performance of PLSR model based on data fusion (combination of Raman and FT-IR data) is better than that based on Raman spectra and similar to that of FT-IR. Overall, Raman spectroscopy, FT-IR spectroscopy, and a combination of both exhibited a potential for the prediction of the beef spoilage.

Internal endpoint temperature (level of cooking doneness) effects on the fatty acid and mineral profiles of grilled lamb m. longissimus lumborum.

This study compared the fatty acid and mineral concentrations of lamb meat that was prepared to different levels of cooking doneness. Ten m. longissimus lumborum were each sectioned into 4 slices that were randomly assigned to be uncooked or grilled to an internal end-point temperature of 60 °C (rare), 71 °C (medium), or 77 °C (well done). It was found that cooking loss increased as the level of cooking doneness increased. The proportion of most major fatty acids were not altered by cooking. However, when adjusted for cooking loss (i.e., mg/135 g serve of lamb as-is equivalent prepared to each level of cooking doneness), the concentration of most major fatty acids, including C16:0, C18:0, C18:1n-9, and many conjugated linoleic acids, were lowered after grilling to any level of cooking doneness and compared to the uncooked samples. The omega-6 to omega-3 ratio was lowest for the uncooked samples and highest for those prepared to a well done level of cooking doneness. Conversely, the concentration of health claimable omega-3 fatty acids in the uncooked meat was retained upon cooking and across all the different internal endpoint temperatures. Calcium, magnesium, phosphorous, potassium, and sodium were reduced with preparation of lamb meat to any level of cooking doneness, compared with uncooked meat. Zinc, iron, and selenium were retained within the cooked samples. These findings show that consumer preference for a level of cooking doneness will have only minor effects on the concentration of minerals and fatty acids in lamb meat.

Site-specific pathophysiology in a neonatal mouse model of gastroparesis.

BACKGROUND: Early-life events impact maturation of the gut microbiome, enteric nervous system, and gastrointestinal motility. We examined three regions of gastric tissue to determine how maternal separation and gut microbes influence the structure and motor function of specific regions of the neonatal mouse stomach. METHODS: Germ-free and conventionally housed C57BL/6J mouse pups underwent timed maternal separation (TmSep) or nursed uninterrupted (controls) until 14 days of life. We assessed gastric emptying by quantifying the progression of gavaged fluorescein isothiocyanate (FITC)-dextran. With isolated rings of forestomach, corpus, and antrum, we measured tone and contractility by force transduction, gastric wall thickness by light microscopy, and myenteric plexus neurochemistry by whole-mount immunostaining. KEY RESULTS: Regional gastric sampling revealed site-specific differences in contractile patterns and myenteric plexus structure. In neonatal mice, TmSep prolonged gastric emptying. In the forestomach, TmSep increased contractile responses to carbachol, decreased muscularis externa and mucosa thickness, and increased the relative proportion of myenteric plexus nNOS+ neurons. Germ-free conditions did not appreciably alter the structure or function of the neonatal mouse stomach and did not impact the changes caused by TmSep. CONCLUSIONS AND INFERENCES: A regional sampling approach facilitates site-specific investigations of murine gastric motor physiology and histology to identify site-specific alterations that may impact gastrointestinal function. Delayed gastric emptying in TmSep is associated with a thinner muscle wall, exaggerated cholinergic contractile responses, and increased proportions of inhibitory myenteric plexus nNOS+ neurons in the forestomach. Gut microbes do not profoundly affect the development of the neonatal mouse stomach or the gastric pathophysiology that results from TmSep.

Vaginal microbial dynamics and pathogen colonization in a humanized microbiota mouse model.

Vaginal microbial composition is associated with differential risk of urogenital infection. Although Lactobacillus spp. are thought to confer protection against infection, the lack of in vivo models resembling the human vaginal microbiota remains a prominent barrier to mechanistic discovery. Using 16S rRNA amplicon sequencing of C57BL/6J female mice, we found that vaginal microbial composition varies within and between colonies across three vivaria. Noting vaginal microbial plasticity in conventional mice, we assessed the vaginal microbiome of humanized microbiota mice (HMbmice). Like the community structure in conventional mice, HMbmice vaginal microbiota clustered into community state types but, uniquely, HMbmice communities were frequently dominated by Lactobacillus or Enterobacteriaceae. Compared to conventional mice, HMbmice were less susceptible to uterine ascension by urogenital pathobionts group B Streptococcus (GBS) and Prevotella bivia. Although Escherichia and Lactobacillus both correlated with the absence of uterine GBS, vaginal pre-inoculation with exogenous HMbmouse-derived E. coli, but not Ligilactobacillus murinus, reduced vaginal GBS burden. Overall, HMbmice serve as a useful model to elucidate the role of endogenous microbes in conferring protection against urogenital pathogens.

Common Variable Immunodeficiency Patient Fecal Microbiota Transplant Recapitulates Gut Dysbiosis.

Purpose: Patients with non-infectious complications have worse clinical outcomes in common variable immunodeficiency (CVID) than those with infections-only. Non-infectious complications are associated with gut microbiome aberrations, but there are no reductionist animal models that emulate CVID. Our aim in this study was to uncover potential microbiome roles in the development of non-infectious complications in CVID. Methods: We examined fecal whole genome shotgun sequencing from patients CVID, and non-infectious complications, infections-only, and their household controls. We also performed Fecal Microbiota transplant from CVID patients to Germ-Free Mice. Results: We found potentially pathogenic microbes Streptococcus parasanguinis and Erysipelatoclostridium ramosum were enriched in gut microbiomes of CVID patients with non-infectious complications. In contrast, Fusicatenibacter saccharivorans and Anaerostipes hadrus, known to suppress inflammation and promote healthy metabolism, were enriched in gut microbiomes of infections-only CVID patients. Fecal microbiota transplant from non-infectious complications, infections-only, and their household controls into germ-free mice revealed gut dysbiosis patterns in recipients from CVID patients with non-infectious complications, but not infections-only CVID, or household controls recipients. Conclusion: Our findings provide a proof of concept that fecal microbiota transplant from CVID patients with non-infectious complications to Germ-Free mice recapitulates microbiome alterations observed in the donors.

Bacteroides ovatus alleviates dysbiotic microbiota-induced intestinal graft-versus-host disease.

Acute gastrointestinal intestinal GVHD (aGI-GVHD) is a serious complication of allogeneic hematopoietic stem cell transplantation, and the intestinal microbiota is known to impact on its severity. However, an association between treatment response of aGI-GVHD and the intestinal microbiota has not been well-studied. In a cohort of patients with aGI-GVHD (n=37), we found that non-response to standard therapy with corticosteroids was associated with prior treatment with carbapenem antibiotics and loss of Bacteroides ovatus from the microbiome. In a mouse model of carbapenem-aggravated GVHD, introducing Bacteroides ovatus reduced severity of GVHD and improved survival. Bacteroides ovatus reduced degradation of colonic mucus by another intestinal commensal, Bacteroides thetaiotaomicron, via its ability to metabolize dietary polysaccharides into monosaccharides, which then inhibit mucus degradation by Bacteroides thetaiotaomicron and reduce GVHD-related mortality.

Choice and placebo expectation effects in the context of pain analgesia.

The current experiment examined whether having choice over treatment options facilitates or inhibits the strength of placebo expectations in the context of pain perception. All participants were exposed to an aversive stimulus (i.e., the cold pressor task), and participants in some conditions were given expectations for two pain-relieving treatments (actually the same inert ointment mixture). Critically, participants in these expectation conditions were also given a choice or not about which of the two treatments they preferred to use. Participants in a control condition were not provided with a treatment expectation. Despite receiving the same inert treatment, participants who had a choice over treatments showed increased placebo analgesia as compared to participants not given a choice and participants in the control condition. Moreover, this effect was mediated by changes in anxiety. Explanations and implications for these results are discussed.

There is no relationship between lamb particle size and consumer scores for tenderness, flavour, juiciness, overall liking or quality rank.

With the aim to define an objective threshold for consumer satisfaction, this study investigated the relationship between lamb particle size data and consumer scores for tenderness, juiciness, flavour and overall liking (sensorial properties). Data were sourced from the longissimus lumborum muscles of 273 Australian Merino lambs, these being aged for 5-d and then analysed for particle size and sensorial properties - the latter using untrained consumer sensory panels. Pearson's correlation and principal component analyses identified no significant relationship between particle size and consumer sensory scores. Linear regression models found the sensorial properties of lamb could not be predicted using particle size, indicating no univariate relationship. Further, a backwards stepwise regression analysis found there to be no multivariate or univariate relationship between the sensorial properties of lamb and its particle size. These findings demonstrate that there is little value in defining a particle size threshold for consumer satisfaction based on the sensorial properties of lamb.