Experimental demonstration of optical stochastic cooling.

Particle accelerators and storage rings have been transformative instruments of discovery, and, for many applications, innovations in particle-beam cooling have been a principal driver of that success1. Stochastic cooling (SC), one of the most important conceptual and technological advances in this area2-6, cools a beam through granular sampling and correction of its phase-space structure, thus bearing resemblance to a 'Maxwell's demon'. The extension of SC from the microwave regime up to optical frequencies and bandwidths has long been pursued, as it could increase the achievable cooling rates by three to four orders of magnitude and provide a powerful tool for future accelerators. First proposed nearly 30 years ago, optical stochastic cooling (OSC) replaces the conventional microwave elements of SC with optical-frequency analogues and is, in principle, compatible with any species of charged-particle beam7,8. Here we describe a demonstration of OSC in a proof-of-principle experiment at the Fermi National Accelerator Laboratory's Integrable Optics Test Accelerator9,10. The experiment used 100-MeV electrons and a non-amplified configuration of OSC with a radiation wavelength of 950 nm, and achieved strong, simultaneous cooling of the beam in all degrees of freedom. This realization of SC at optical frequencies serves as a foundation for more advanced experiments with high-gain optical amplification, and advances opportunities for future operational OSC systems with potential benefit to a broad user community in the accelerator-based sciences.

Voluntary sustainability standards could significantly reduce detrimental impacts of global agriculture.

Voluntary sustainability standards (VSS) are stakeholder-derived principles with measurable and enforceable criteria to promote sustainable production outcomes. While institutional commitments to use VSS to meet sustainable procurement policies have grown rapidly over the past decade, we still have relatively little understanding of the (i) direct environmental benefits of large-scale VSS adoption; (ii) potential perverse indirect impacts of adoption; and (iii) implementation pathways. Here, we illustrate and address these knowledge gaps using an ecosystem service modeling and scenario analysis of Bonsucro, the leading VSS for sugarcane. We find that global compliance with the Bonsucro environmental standards would reduce current sugarcane production area (-24%), net tonnage (-11%), irrigation water use (-65%), nutrient loading (-34%), and greenhouse gas emissions from cultivation (-51%). Under a scenario of doubled global sugarcane production, Bonsucro adoption would further limit water use and greenhouse gas emissions by preventing sugarcane expansion into water-stressed and high-carbon stock ecosystems. This outcome was achieved via expansion largely on existing agricultural lands. However, displacement of other crops could drive detrimental impacts from indirect land use. We find that over half of the potential direct environmental benefits of Bonsucro standards under the doubling scenario could be achieved by targeting adoption in just 10% of global sugarcane production areas. However, designing policy that generates the most environmentally beneficial Bonsucro adoption pathway requires a better understanding of the economic and social costs of VSS adoption. Finally, we suggest research directions to advance sustainable consumption and production.

A prediction model of military combat and training exposures on VA service-connected disability: a CENC study.

Background: Research has shown that number of and blast-related Traumatic Brain Injuries (TBI) are associated with higher levels of service-connected disability (SCD) among US veterans. This study builds and tests a prediction model of SCD based on combat and training exposures experienced during active military service.Methods: Based on 492 US service member and veteran data collected at four Department of Veterans Affairs (VA) sites, traditional and Machine Learning algorithms were used to identify a best set of predictors and model type for predicting %SCD ≥50, the cut-point that allows for veteran access to 0% co-pay for VA health-care services.Results: The final model of predicting %SCD ≥50 in veterans revealed that the best blast/injury exposure-related predictors while deployed or non-deployed were: 1) number of controlled detonations experienced, 2) total number of blast exposures (including controlled and uncontrolled), and 3) the total number of uncontrolled blast and impact exposures.Conclusions and Relevance: We found that the highest blast/injury exposure predictor of %SCD ≥50 was number of controlled detonations, followed by total blasts, controlled or uncontrolled, and occurring in deployment or non-deployment settings. Further research confirming repetitive controlled blast exposure as a mechanism of chronic brain insult should be considered.

Assessment of beta-cell function in young patients with type 2 diabetes: arginine-stimulated insulin secretion may reflect beta-cell reserve.

OBJECTIVE: Simple methods for the evaluation of dynamic b-cell function in epidemiological and clinical studies of patients with type 2 diabetes (T2D) are needed. The aim of this study was to evaluate the dynamic beta-cell function in young patients with T2D with different disease durations and treatments. METHODS: Overall, 54 subjects with T2D from the Diabetes Incidence Study in Sweden (DISS) and 23 healthy control participants were included in this cross-sectional study. Beta-cell function was assessed by intravenous (i.v.) administration of arginine followed by i.v. glucose. The acute insulin and C-peptide responses to arginine (AIRarg and Ac-pepRarg, respectively) and to glucose (AIRglu and Ac-pepRglu, respectively)were estimated.Homeostasis model assessment of b-cell function(HOMA-b) andCpeptide assessments were also used for comparisons between patients with T2D and control participants. RESULTS: AIRarg and Ac-pepRarg, but not AIRglu and Ac-pepRglu, could differentiate between patients with different disease durations. AIRglu values were 89% (P < 0.001) lower and AIRarg values were 29% (P < 0.01) lower in patients with T2D compared with control participants. HOMA-b and fasting plasma C-peptide levels did not differ between the T2D and control groups. CONCLUSION: In young patients with T2D, the insulin secretory response to i.v. glucose is markedly attenuated, whereas i.v. arginine-stimulated insulin release is better preserved and can distinguish between patients with different disease duration and antidiabetic therapies. This suggests that the i.v. arginine stimulation test may provide an estimate of functional beta-cell reserve.

Technical aspects of botulinum toxin type A injection in the bladder to treat urinary incontinence: reviewing the procedure.

AIMS: Standardise the injection technique with botulinum toxin type A (BoNT A) in the bladder of patients with overactive bladder (OAB) [idiopathic overactive bladder (iOAB) or neurogenic overactive bladder (nOAB) with urinary incontinence], using a literature review and a survey of an International expert panel. METHODS: PubMed literature searches of BoNT A in adults with iOAB/nOAB together with a survey of 13 experts from 10 countries. RESULTS: Data from 21 articles and completed questionnaires were collated. The procedure can be carried out in an out-/inpatient setting. Dose used in clinical studies vs. clinical practice was 300 and 200 U for nOAB and 200 and 100 U for iOAB. Recent studies have also demonstrated that there are no clinically relevant benefits between 100 and 150 U in iOAB or between 300 and 200 U in nOAB, though adverse effects are increased with higher doses. Usually, 30 sites for nOAB (range: 6.7-10 U/ml) and 20-30 sites for iOAB (range: 5-10 U/ml) are injected in clinical studies vs. 20-30 sites of 1 ml/injection for 200 U in nOAB and 10-20 sites of 0.5-1 ml/injection for 100 U in iOAB in clinical practice. BoNT A is usually injected directly into the detrusor, sparing the trigone. Flexible or rigid cystoscopes are used. The needle should be typically 22-27 gauge and 4 mm in length and should have a stopper to avoid any leakage or perforation of the bladder wall while ensuring a targeted injection. CONCLUSION: Based on the literature and survey analysis, recommendations are proposed for the standardisation of the injection procedure.

Blood glucose levels in children with Type 1 diabetes attending a residential diabetes camp: a 2-year review.

AIMS: The objective of this retrospective analysis of blood glucose values at a week-long residential summer camp for children with Type 1 diabetes was to provide experiential data to reinforce current summer camp guidelines and to determine if specific interventions implemented between 2009 and 2010 were effective in lowering average blood glucose among our campers without increasing risk of hypoglycaemia. METHODS: Blood glucose records were obtained from a random selection of children who attended six 1-week camp sessions, three each in 2009 and 2010. Five values per day: pre-meal breakfast, lunch and dinner, pre-evening snack and midnight values were analysed. RESULTS: A total of 13,267 blood glucose values were included. There were no severe hypoglycaemic episodes, seizures or need for full-dose glucagon or intravenous glucose in either year. Mean blood glucose was significantly lower in 2010 compared with 2009 (9.22 vs. 10.06 mmol/l, P < 0.001). Older age and camp year were associated with lower mean blood glucose, even when controlling for gender and duration of diabetes. CONCLUSIONS: This analysis is the largest so far conducted at a residential diabetes camp. Mean blood glucose levels were lower than other published studies. Although we cannot attribute a cause-and-effect relationship between our interventions and the improvement in blood glucose between 2009 and 2010, the use of pre-meal insulin bolus doses, low glycaemic meals and highlighting blood glucose levels in logs before being reviewed by endocrinologists are strongly encouraged. From this study we hope to establish benchmarks for comparison among camps and begin to identify best practices.

Physical activity engendering loads from diverse directions augments the growing skeleton.

OBJECTIVE: An experiment was conducted to determine if modifying habitual activities to involve mechanical loading from more diverse directions can enhance the growing skeleton. METHODS: Growing female C57BL/6J mice were housed individually for 3 months in enclosures designed to accentuate either non-linear locomotion (diverse-orientation loading) or linear locomotion (stereotypic-orientation loading) (n=10/cage type). Behavioral assessments were performed daily to quantify cage activity level. Following the experiment, trabecular and cortical bone structure in the humeral head and distal femoral metaphysis were analyzed with µCT. RESULTS: Throughout the experiment, groups did not differ in cage activity level. Yet, following the experiment, the proximal humeri of mice that experienced increased diverse-orientation loading had significantly greater trabecular bone volume fraction (p=0.004), greater cortical bone area (p=0.005), greater cortical area fraction (p=0.0007), and thicker cortices (p=0.002). No significant group differences were detected in the distal femoral metaphysis. CONCLUSIONS: Diverting habitual activities to entail loading from more diverse orientations can augment the growing mouse skeleton. This study suggests that low-intensity activities that produce loads from diverse directions may represent a viable alternative to vigorous, high-impact exercise as a means of benefiting skeletal health during growth.

Mammalian SWI/SNF complexes promote MyoD-mediated muscle differentiation.

Mammalian SWI/SNF complexes are ATP-dependent chromatin remodeling enzymes that have been implicated in the regulation of gene expression, cell-cycle control and oncogenesis. MyoD is a muscle-specific regulator able to induce myogenesis in numerous cell types. To ascertain the requirement for chromatin remodeling enzymes in cellular differentiation processes, we examined MyoD-mediated induction of muscle differentiation in fibroblasts expressing dominant-negative versions of the human brahma-related gene-1 (BRG1) or human brahma (BRM), the ATPase subunits of two distinct SWI/SNF enzymes. We find that induction of the myogenic phenotype is completely abrogated in the presence of the mutant enzymes. We further demonstrate that failure to induce muscle-specific gene expression correlates with inhibition of chromatin remodeling in the promoter region of an endogenous muscle-specific gene. Our results demonstrate that SWI/SNF enzymes promote MyoD-mediated muscle differentiation and indicate that these enzymes function by altering chromatin structure in promoter regions of endogenous, differentiation-specific loci.

Cilia regeneration in Tetrahymena and its inhibition by colchicine.

The cilia of Tetrahymena were amputated by the use of a procedure in which the cells remained viable and regenerated cilia. Deciliated cells were nonmotile, and cilia regeneration was assessed by scoring the percentage of motile cells at intervals following deciliation. After a 30-min lag, the deciliated cells rapidly recovered motility until more than 90% of the cells were motile at 70 min after amputation. Cycloheximide inhibited both protein synthesis and cilia regeneration. This indicated that cilia formation in Tetrahymena was dependent on protein synthesis after amputation. Conversely, colchicine was found to inhibit cilia regeneration without affecting either RNA or protein synthesis. This observation suggested the action of colchicine to be an interference with the assembly of ciliary subunit proteins. The finding that colchicine binds to microtubule protein subunits isolated from cilia and flagella (13) supports this possibility. The potential of the colchicine-blocked cilia-regenerating system in Tetrahymena for studying the assembly of microtubule protein subunits during cilia formation and for isolating ciliary precursor proteins is discussed.

Chlamydomonas flagella. II. The distribution of tubulins 1 and 2 in the outer doublet microtubules.

Quantitative ultrastructural analysis and quantitative gel electrophoresis of preparations of selectively solubilized Chlamydomonas outer doublets indicated that tubulins 1 and 2 were present in both the A tubule and the B tubule, and that only tubulin 1 was present in the three protofilaments which form the wall ("partition") between the lumens of the A and B tubules. The data suggested that the remaining protofilaments of the outer doublet were grouped together in pairs containing the same type of tubulin, pairs containing tubulin 1 alternating with pairs containing tubulin 2. These findings were used to construct models for the arrangement of the two tubulins in the outer doublet. Further analysis by isoelectric focusing resolved tubulins 1 and 2 into at least five bands.

Chlamydomonas flagella. I. Isolation and electrophoretic analysis of microtubules, matrix, membranes, and mastigonemes.

Methods were developed for the isolation of Chlamydomonas flagella and for their fractionation into membrane, mastigoneme, "matrix," and axoneme components. Each component was studied by electron microscopy and acrylamide gel electrophoresis. Purified membranes retained their tripartite ultrastructure and were shown to contain one high molecular weight protein band on electrophoresis in sodium dodecyl sulfate (SDS)-urea gels. Isolated mastigonemes (hairlike structures which extend laterally from the flagellar membrane in situ) were of uniform size and were constructed of ellipsoidal subunits joined end to end. Electrophoretic analysis of mastigonemes indicated that they contained a single glycoprotein of approximately 170,000 daltons The matrix fraction contained a number of proteins (particularly those of the amorphous material surrounding the microtubules), which became solubilized during membrane removal. Isolated axonemes retained the intact "9 + 2" microtubular structure and could be subfractionated by treatment with heat or detergent. Increasing concentrations of detergent solubilized axonemal microtubules in the following order: one of the two central tubules; the remaining central tubule and the outer wall of the B tubule; the remaining portions of the B tubule; the outer wall of the A tubule; the remainder of the A tubule with the exception of a ribbon of three protofilaments. These three protofilaments appeared to be the "partition" between the lumen of the A and B tubule. Electrophoretic analysis of isolated outer doublets of 9 + 2 flagella of wild-type cells and of "9 + 0" flagella of paralyzed mutants indicated that the outer doublets and central tubules were composed of two microtubule proteins (tubulins 1 and 2) Tubulins 1 and 2 were shown to have apparent molecular weights of 56,000 and 53,000 respectively

Dyskinesias elicited by methamphetamine: susceptibility of former methadone-consuming monkeys.

Rhesus monkeys with a history of drinking methadone but currently drug-free and control monkeys with no drug history were injected with methamphetamine hydrochloride (2 to 5 milligrams per kilogram of body weight). In six of seven monkeys which had consumed methadone the lowest dose immediately elicited pronounced oral dyskinesias virtually identical to those of human tardive dyskinesia. The control monkeys did not exhibit oral dyskinesias even after prolonged treatment with the highest dose. The clincial implications may be related to the functioning of brain dopaminergic systems.

Organic superconductors--new benchmarks.

Recent advances in the design and synthesis of organic synthetic metals have yielded materials that have the highest superconducting transition temperatures (T(c) approximately 13 kelvin) reported for these systems. These materials have crystal structures consisting of alternating layers of organic donor molecules and inorganic anions. Organic superconductors have various electronic and magnetic properties and crystal structures that are similar to those of the inorganic copper oxide superconductors (which have high T(c) values); these similarities include highly anisotropic conductivities, critical fields, and short coherence lengths. The largest number of organic superconductors, including those with the highest T(c) values, are charge-transfer salts derived from the electron donor molecule BEDT-TTF or ET [bis(ethylenedithio)-tetrathiafulvalene]. The synthesis and crystal structures of these salts are discussed; their electrical, magnetic, and band electronic structure properties and their many similarities to the copper oxide superconductors are treated as well.

Does Cellular Metabolism from Primary Fibroblasts and Oxidative Stress in Blood Differ between Mammals and Birds? The (Lack-thereof) Scaling of Oxidative Stress.

As part of mitonuclear communication, retrograde and anterograde signaling helps maintain homeostasis under basal conditions. Basal conditions, however, vary across phylogeny. At the cell-level, some mitonuclear retrograde responses can be quantified by measuring the constitutive components of oxidative stress, the balance between reactive oxygen species (ROS) and antioxidants. ROS are metabolic by-products produced by the mitochondria that can damage macromolecules by structurally altering proteins and inducing mutations in DNA, among other processes. To combat accumulating damage, organisms have evolved endogenous antioxidants and can consume exogenous antioxidants to sequester ROS before they cause cellular damage. ROS are also considered to be regulated through a retrograde signaling cascade from the mitochondria to the nucleus. These cellular pathways may have implications at the whole-animal level as well. For example, birds have higher basal metabolic rates, higher blood glucose concentration, and longer lifespans than similar sized mammals, however, the literature is divergent on whether oxidative stress is higher in birds compared with mammals. Herein, we collected literature values for whole-animal metabolism of birds and mammals. Then, we collected cellular metabolic rate data from primary fibroblast cells isolated from birds and mammals and we collected blood from a phylogenetically diverse group of birds and mammals housed at zoos and measured several parameters of oxidative stress. Additionally, we reviewed the literature on basal-level oxidative stress parameters between mammals and birds. We found that mass-specific metabolic rates were higher in birds compared with mammals. Our laboratory results suggest that cellular basal metabolism, total antioxidant capacity, circulating lipid damage, and catalase activity were significantly lower in birds compared with mammals. We found no body-size correlation on cellular metabolism or oxidative stress. We also found that most oxidative stress parameters significantly correlate with increasing age in mammals, but not in birds; and that correlations with reported maximum lifespans show different results compared with correlations with known aged birds. Our literature review revealed that basal levels of oxidative stress measurements for birds were rare, which made it difficult to draw conclusions.

Predicting aged pork quality using a portable Raman device.

The utility of Raman spectroscopic signatures of fresh pork loin (1 d & 15 d postmortem) in predicting fresh pork tenderness and slice shear force (SSF) was determined. Partial least square models showed that sensory tenderness and SSF are weakly correlated (R2 = 0.2). Raman spectral data were collected in 6 s using a portable Raman spectrometer (RS). A PLS regression model was developed to predict quantitatively the tenderness scores and SSF values from Raman spectral data, with very limited success. It was discovered that the prediction accuracies for day 15 post mortem samples are significantly greater than that for day 1 postmortem samples. Classification models were developed to predict tenderness at two ends of sensory quality as "poor" vs. "good". The accuracies of classification into different quality categories (1st to 4th percentile) are also greater for the day 15 postmortem samples for sensory tenderness (93.5% vs 76.3%) and SSF (92.8% vs 76.1%). RS has the potential to become a rapid on-line screening tool for the pork producers to quickly select meats with superior quality and/or cull poor quality to meet market demand/expectations.

Mutations in the homologous ZDS1 and ZDS2 genes affect cell cycle progression.

The Saccharomyces cerevisiae ZDS1 and ZDS2 genes were identified as multicopy suppressors in distinct genetic screens but were found to encode highly similar proteins. We show that at semipermissive temperatures, a yeast strain with a cdc28-1N allele was uniquely deficient in plasmid maintenance in comparison with strains harboring other cdc28 thermolabile alleles. Quantitative analysis of plasmid loss rates in cdc28-1N strains carrying plasmids with multiple replication origins suggests that a defect in initiating DNA replication probably causes this plasmid loss phenotype. The ZDS1 gene was isolated as a multicopy suppressor of the cdc28-1N plasmid loss defect. A zds1 deletion exhibits genetic interactions with cdc28-1N but not with other cdc28 alleles. SIN4 encodes a protein which is part of the RNA polymerase II holoenzyme-mediator complex, and a sin4 null mutation has pleiotropic effects suggesting roles in transcriptional regulation and chromatin structure. The ZDS2 gene was isolated as a multicopy suppressor of the temperature-sensitive growth defect caused by the sin4 null mutation. Disruption of either ZDS1 or ZDS2 causes only modest phenotypes. However, a strain with both ZDS1 and ZDS2 disrupted is extremely slowly growing, has marked defects in bud morphology, and shows defects in completing S phase or entering mitosis.

Mammalian SWI-SNF complexes contribute to activation of the hsp70 gene.

ATP-dependent chromatin-remodeling complexes are conserved among all eukaryotes and function by altering nucleosome structure to allow cellular regulatory factors access to the DNA. Mammalian SWI-SNF complexes contain either of two highly conserved ATPase subunits: BRG1 or BRM. To identify cellular genes that require mammalian SWI-SNF complexes for the activation of gene expression, we have generated cell lines that inducibly express mutant forms of the BRG1 or BRM ATPases that are unable to bind and hydrolyze ATP. The mutant subunits physically associate with at least two endogenous members of mammalian SWI-SNF complexes, suggesting that nonfunctional, dominant negative complexes may be formed. We determined that expression of the mutant BRG1 or BRM proteins impaired the ability of cells to activate the endogenous stress response gene hsp70 in response to arsenite, a metabolic inhibitor, or cadmium, a heavy metal. Activation of hsp70 by heat stress, however, was unaffected. Activation of the heme oxygenase 1 promoter by arsenite or cadmium and activation of the cadmium-inducible metallothionein promoter also were unaffected by the expression of mutant SWI-SNF components. Analysis of a subset of constitutively expressed genes revealed no or minimal effects on transcript levels. We propose that the requirement for mammalian SWI-SNF complexes in gene activation events will be specific to individual genes and signaling pathways.

Proteomic features linked to tenderness of aged pork loins.

There is considerable evidence that the protein component of fresh pork makes a major contribution to tenderness. In particular, the proteomic profile can be linked to postmortem events including pH decline, tissue oxidation, and protein degradation. The objectives for this study were to determine differences in sarcoplasmic proteomes that contribute to tenderness variation in aged pork longissimus dorsi muscles (LM). A defined set of pork loins selected to be similar in pH, color, and lipid yet different in tenderness were used. Pork loins were assigned to tenderness groups based on their star probe values; a high star probe group (HSP; n=12 mean star probe 7.75 kg) and low star probe group (LPS; n=12 star probe 4.95 kg) Samples were selected for proteomic experiments based on star probe values, and selected samples were within specified ranges for ultimate pH (5.54-5.86), marbling score (1.0-3.0), and percent total lipid (1.61-3.37%). Two-dimensional difference in gel electrophoresis (2D-DIGE) and mass spectrometry were used to examine sarcoplasmic protein abundance and potential modifications. Proteins spots that were significantly different across groups were selected for identification. Results from 2D-DIGE showed that HSP samples had significantly more abundant metabolic, stress response, and regulatory proteins in the sarcoplasmic fraction compared with LSP samples. The stress response protein peroxiredoxin-2 was more abundant in HSP samples as determined by 2D-DIGE ( ≤ 0.01; 2 spots) and western blot assay ( = 0.02). Low star probe samples showed significantly more degradation of the structural protein desmin in 2D-DIGE ( < 0.01) and western blot assay ( < 0.01). These results demonstrate that extreme proteolytic differences influenced measured tenderness of LSP and HSP samples and that soluble desmin and peroxiredoxin-2 may be used as biomarkers to differentiate between tough and tender aged pork products.

Spatial and temporal microbial pollution patterns in a tropical estuary during high and low river flow conditions.

Spatial and temporal patterns of coastal microbial pollution are not well documented. Our study examined these patterns through measurements of fecal indicator bacteria (FIB), nutrients, and physiochemical parameters in Hilo Bay, Hawai'i, during high and low river flow. >40% of samples tested positive for the human-associated Bacteroides marker, with highest percentages near rivers. Other FIB were also higher near rivers, but only Clostridium perfringens concentrations were related to discharge. During storms, FIB concentrations were three times to an order of magnitude higher, and increased with decreasing salinity and water temperature, and increasing turbidity. These relationships and high spatial resolution data for these parameters were used to create Enterococcus spp. and C. perfringens maps that predicted exceedances with 64% and 95% accuracy, respectively. Mapping microbial pollution patterns and predicting exceedances is a valuable tool that can improve water quality monitoring and aid in visualizing FIB hotspots for management actions.

Postmortem protein degradation is a key contributor to fresh pork loin tenderness.

The objective of this study was to determine factors that influence tenderness independent of variation in pH, color, or marbling. To achieve the objective, 2 sample groups were chosen from a population of 159 pork loins aged 11 to 16 d. Predetermined ranges (ultimate pH, 5.54 to 5.86; marbling score, 1.0 to 3.0; percent total lipid, 1.61 to 3.37%) were defined for inclusion of individual loins in the study. The pork loins with the greatest ( = 12) and least ( = 12) Instron star probe values were assigned to 2 classification groups. The high star probe group had an average star probe that was 2.8 kg greater than the low star probe group (7.75 vs. 4.95 kg). Pork quality and sensory characteristics of pH, subjective and instrumental color values, cook loss, sensory tenderness, chewiness, juiciness, pork flavor, and off flavor were determined on fresh, never frozen pork chops. Lipid content, sarcomere length, myosin heavy-chain profile, and calpain autolysis were determined. Degradation of troponin-T, desmin, filamin, and titin were evaluated on the protein extracts from each sample. Pork loin pH, subjective color scores, Minolta L values, sarcomere length, and myosin heavy-chain composition were not different across groups. Chops from the low star probe group had a significantly greater marbling score (2.3 vs. 1.9) and lipid content (2.61 vs. 2.23%). Calpain-1 was completely autolyzed in both high and low star probe samples, demonstrating that calpain-1 potentially had been active in all samples. Low star probe whole-muscle protein extracts had more troponin-T ( < 0.01), desmin ( < 0.01), and filamin degradation ( < 0.01) than high star probe samples. Both classification groups showed degradation of titin. Remarkably, some high star probe samples still had observable intact bands of titin on SDS-PAGE gels. These results demonstrate that significant variation in instrumental tenderness is observed within a moderate pH range. Lipid content and proteolysis both appear to contribute to this variation.