Two levels of specialization in bacteraemic Escherichia coli strains revealed by their comparison with commensal strains.

Bacteraemia caused by Escherichia coli are particularly frequent and severe, contrasting with the commensal character of the strains found in the digestive tract. A better understanding of the relationships between strains of both origins is needed to unravel the pathogenesis of this disease. Two hundred and forty-three commensal strains were compared to 243 bacteraemic strains isolated from adult hosts matched in terms of gender and age, and from similar location and epoch. Phylogenetic grouping, O-type determination, virulence factor content and antibiotic resistance were compared. Compared to commensal strains, the bacteraemic strains were characterized by a higher proportion of B2, C and D phylogroups, and a lower proportion of A, E and F phylogroups. They also had a lower proportion of the B2 subgroup IV (STc141), a higher proportion of virulence factors, and a higher frequency of antibiotic resistance. These differences were more marked for the bacteraemic strains of urinary tract origin with the presence of specific clones, whereas the bacteraemic strains of digestive origin remained non-significantly different from the commensal strains, except for their antibiotic resistance. Thus, two levels of specialization from commensal strains were demonstrated in the bacteraemic strains: resistance to antibiotics in all cases, and virulence for those of urinary tract origin.

Myostatin and the skeletal muscle atrophy and hypertrophy signaling pathways.

Myostatin, a member of the transforming growth factor-ß superfamily, is a potent negative regulator of skeletal muscle growth and is conserved in many species, from rodents to humans. Myostatin inactivation can induce skeletal muscle hypertrophy, while its overexpression or systemic administration causes muscle atrophy. As it represents a potential target for stimulating muscle growth and/or preventing muscle wasting, myostatin regulation and functions in the control of muscle mass have been extensively studied. A wealth of data strongly suggests that alterations in skeletal muscle mass are associated with dysregulation in myostatin expression. Moreover, myostatin plays a central role in integrating/mediating anabolic and catabolic responses. Myostatin negatively regulates the activity of the Akt pathway, which promotes protein synthesis, and increases the activity of the ubiquitin-proteasome system to induce atrophy. Several new studies have brought new information on how myostatin may affect both ribosomal biogenesis and translation efficiency of specific mRNA subclasses. In addition, although myostatin has been identified as a modulator of the major catabolic pathways, including the ubiquitin-proteasome and the autophagy-lysosome systems, the underlying mechanisms are only partially understood. The goal of this review is to highlight outstanding questions about myostatin-mediated regulation of the anabolic and catabolic signaling pathways in skeletal muscle. Particular emphasis has been placed on (1) the cross-regulation between myostatin, the growth-promoting pathways and the proteolytic systems; (2) how myostatin inhibition leads to muscle hypertrophy; and (3) the regulation of translation by myostatin.

Clinical features and outcomes of patients with pancreatic cancer requiring unplanned medical ICU admission: A retrospective multicenter study.

BACKGROUND: We sought to describe the reasons for intensive care unit (ICU) admission and outcomes of patients with pancreatic cancer requiring unplanned medical ICU admission. PATIENTS AND METHODS: Retrospective cohort study in five ICUs from 2009 to 2020. All patients with pancreatic cancer admitted to the ICU were included. Patients having undergone recent surgery were excluded (< 4 weeks). RESULTS: 269 patients were included. Tumors were mainly adenocarcinoma (90%). Main reason for admission was sepsis/septic shock (32%) with a biliary tract infection in 44 (51%) patients. Second reason for admission was gastrointestinal bleeding (28%). ICU and 3-month mortality rates were 26% and 59% respectively. Performance status 3-4 (odds ratio OR 3.58), disease status (responsive/stable -ref-, newly diagnosed OR 3.25, progressive OR 5.99), mechanical ventilation (OR 8.03), vasopressors (OR 4.19), SAPS 2 (OR 1.69) and pH (OR 0.02) were independently associated with ICU mortality. Performance status 3-4 (Hazard ratio HR 1.96) and disease status (responsive/stable -ref-, newly diagnosed HR 2.67, progressive HR 4.14) were associated with 3-month mortality. CONCLUSION: Reasons for ICU admissions of pancreatic cancer patients differ from those observed in other solid cancer. Short- and medium-term mortality are strongly influenced by performance status and disease status at ICU admission.

[Updated indications and contraindications in 2022 for lung transplantation in France]. / Transplantation pulmonaire en France : actualisation des indications et contre-indications en 2022.

Lung transplantation (LTx) is the last-resort treatment for end-stage respiratory insufficiency, whatever its origin, and represents a steadily expanding field of endeavor. Major developments have been impelled over the years by painstaking efforts at LTx centers to improve donor and recipient selection, and multifaceted attempts have been made to meet the challenges raised by surgical management, perioperative care, and long-term medical complications. The number of procedures has increased, leading to improved post-LTx prognosis. One consequence of these multiple developments has been a pruning away of contraindications over time, which has, in some ways, complicated the patient selection process. With these considerations in mind, the Francophone Pulmonology Society (Société de Pneumology de Langue Française [SPLF]) has set up a task force to produce up-to-date working guidelines designed to assist pulmonologists in managing end-stage respiratory insufficiency, determining which patients may be eligible for LTx, and appropriately timing LTx-center referral. The task force has examined the most recent literature and evaluated the risk factors that continue to limit patient survival after LTx. Ideally, the objectives of LTx are to prolong life while improving quality of life. The guidelines developed by the task force apply to a limited resource and are consistent with the ethical principles described below.

What is the impact of the rearing management applied during the heifers' whole life on the toughness of five raw rib muscles in relation with carcass traits?

The aims of this study were, analysing the effects of rearing managements, carcass traits, and muscle type (M. complexus [CP], M. infraspinatus [IF], M. longissimus [LM], M. rhomboideus [RH], and M. serratus ventralis [SV]) on toughness of raw meat; developing prediction models to act on their toughness. According to our results obtained on the data of 77 heifers, the IF raw muscle was the toughest and appeared the most sensitive to a change in the rearing management. The four other raw muscles had a similar toughness within heifers from the same rearing management. The five raw muscles were less tough when the carcass was heavier and had higher dressing percentage and conformation. The 3 models explained about 40% of the variability observed. Our models showed that it is possible to improve the potential tenderness of raw meat, acting on: age of the heifer's mother, growth rate during the growth and fattening periods, slaughter age, carcass weight and temperature 24 h post-mortem.

Clinical characteristics of and outcomes for patients with COVID-19 and comorbid lung diseases primarily hospitalized in a conventional pulmonology unit: A retrospective study.

BACKGROUND: Scant data are currently available about a potential link between comorbid chronic lung diseases (CLD) and the risk and severity of the coronavirus disease 2019 (COVID-19) infection. METHODS: To describe the clinical characteristics of and outcomes for patients with COVID-19 infection, including patients with comorbid respiratory diseases, who have been primarily hospitalized in the pulmonology department of Strasbourg University Hospital, France. In this retrospective, single-center study, we included all confirmed cases of COVID-19 from March 3 to April 15, 2020. We then compared the symptoms, biological and radiological findings, and outcomes for patients with and without CLD. RESULTS: Of the 124 patients that were enrolled, the median age was 62 years, and 75 patients (60%) were male. Overall, 40% of patients (n=50) had preexisting CLD, including chronic obstructive pulmonary disease (COPD) (n=15, 12%) and asthma (n=19, 15%). Twenty-eight patients were transferred to the intensive care unit (ICU), and six patients died in our unit. CLD were not predictive of ICU hospitalization, but a significantly higher total mortality was observed (17.6% vs. 5.5%, P<0.05) in these patients. CONCLUSIONS: Our results suggest the lack of an over-representation of CLD in COVID-19, representing 40% of patients in this cohort and even within a pulmonology department. CLD were not a risk factor for ICU management. However, a tendency to higher global mortality was observed in COVID-19 patients with CLD. Further studies are warranted to determine the risk of COVID-19 for patients with comorbid CLD.

Influence of the rearing managements and carcass traits on the sensory properties of two muscles: Longissimus thoracis and rectus abdominis.

The aim of this study was to analyse simultaneously the effect of rearing managements (RM), carcass traits, muscle type (longissimus thoracis, LT and rectus abdominis, RA) and their interactions on colour (system L*a*b*), sensory and rheological properties of 77 heifers. The data used were 46 rearing factors defining four RM applied during the heifers' whole life from and 5 carcass traits discriminating two carcass quality clusters (Low and High quality). The results showed that the RM had an impact on the carcass and meat quality traits. The redness and the overall acceptability of LT meat were more sensitive to variation of RM than RA meat. The tenderness of LT and RA were similar or not according to the RM. Higher tenderness was obtained from high carcass quality irrespective the muscle. These results show that similar carcass and meat qualities can be obtained with different RM. They also demonstrated that it is also possible to manage jointly carcass and meat qualities.

Are there consistent relationships between major connective tissue components, intramuscular fat content and muscle fibre types in cattle muscle?

Intramuscular connective tissue (IMCT) is mainly composed of several fibrils (known as total collagen (TCol)) linked between each other by different chemical cross-links (CLs), the whole being embedded in a matrix of proteoglycans (PGs). In the field of beef quality, there is limited information on the role of CLs and PGs. Accordingly, several authors suggest that, to investigate the role of IMCT, it is important to investigate them just like TCol and insoluble collagen (ICol). In muscle, there are two other components, the muscle fibres and intramuscular fat (IMF) content. There are limited data on the relationships between these three components of muscle and then on possibility to independently manipulate these characteristics in order to control the final quality of meat. The present study aimed to investigate whether consistent relationships exist between these different components of muscle. Therefore, the present study compared four muscles of two cattle types (dairy and beef) to determine associations between TCol, ICol, CLs and PGs. Data were analysed across and within muscle (M) and animal type (AT) based on residuals. There was a strong M and AT effect for all muscle characteristics and an interaction M × AT for type I muscle fibres and IMF. Correlations between TCol, ICol and their CLs were M- and AT-independent. Total proteoglycans were positively correlated with TCol and ICol in a muscle-dependent manner irrespective of AT, but no correlation was found with CLs. On the contrary, CLs were negatively correlated with the ratio TPGs : TCol in an M-dependent manner, irrespective of AT. TCol, ICol and CLs were positively and negatively correlated with type IIA and IIB+X muscle fibres only in longissimus thoracis (LT) muscle, regardless the AT. Insoluble collagen was the only parameter of IMCT to be correlated with type I muscle fibres but only in LT muscle, irrespective of AT. There was no correlation between PGs and muscle fibre types, but PGs were the only IMCT component to be related with IMF in an M-dependent manner, irrespective of AT. Finally, there was no correlation between muscle fibre types and IMF content within M and AT. This study revealed that there is a strong relationship between IMCT components irrespective of M, an M-dependent relationship between the IMCT components and muscle fibre types and few (only with PGs) or no relationship between IMF and IMCT and muscle fibres.

Interrelationships between meat quality traits, texture measurements and physicochemical characteristics of M. rectus abdominis from Charolais heifers.

Ninety-nine Charolais heifers were used to study the variability of meat quality traits in relation to the physicochemical characteristics of M. rectus abdominis. The heifers of the same trade class were slaughtered at 33months of age (±4months) and 381kg carcass weight (±31kg). Muscle and bone development scores were evaluated before slaughter. Carcass weight, slaughter age and life average daily gain were recorded. Shear force measurements and meat quality traits were evaluated after 14days of aging. Some physicochemical characteristics were measured 24h post-slaughter. Tenderness was correlated with slaughter age (r=-0.31), bone development (r=-0.22) and life average daily gain (r=+0.37). Tenderness was significantly related to total collagen content (r=-0.24), lipid content (r=+0.27) and I myosin heavy chain proportion (r=+0.24). Juiciness was positively correlated with lipid content (r=+0.31) and I myosin heavy chain proportion (r=+0.20). Flavor intensity was correlated with lipid content (r=+0.26) and mean fiber area (r=+0.24). Shear force was correlated with total collagen, lipid and 27K proteasome sub-unit contents. Taking animal characteristics and muscle properties together in a multiple regression analysis increased the explained tenderness variability to 33%. The independent variables listed in order of importance were life average daily gain, total collagen content, bone development, lipid content, I myosin heavy chain isoform proportion, shear force of broiled meat and slaughter age.

Statistical model choice including variable selection based on variable importance: A relevant way for biomarkers selection to predict meat tenderness.

In this paper, we describe a new computational methodology to select the best regression model to predict a numerical variable of interest Y and to select simultaneously the most interesting numerical explanatory variables strongly linked to Y. Three regression models (parametric, semi-parametric and non-parametric) are considered and estimated by multiple linear regression, sliced inverse regression and random forests. Both the variables selection and the model choice are computational. A measure of importance based on random perturbations is calculated for each covariate. The variables above a threshold are selected. Then a learning/test samples approach is used to estimate the Mean Square Error and to determine which model (including variable selection) is the most accurate. The R package modvarsel (MODel and VARiable SELection) implements this computational approach and applies to any regression datasets. After checking the good behavior of the methodology on simulated data, the R package is used to select the proteins predictive of meat tenderness among a pool of 21 candidate proteins assayed in semitendinosus muscle from 71 young bulls. The biomarkers were selected by linear regression (the best regression model) to predict meat tenderness. These biomarkers, we confirm the predominant role of heat shock proteins and metabolic ones.

Acute Cardiac Failure Due to Takotsubo Cardiomyopathy Secondary to a Phone Call for Lung Transplantation: A Case Report.

Lung transplantation is a therapeutic option for certain end-stage lung diseases. The phone call for lung transplantation is a major event in the life of these patients; as a result, it can generate significant stress. We herein present the case of a 58-year-old female patient with end-stage chronic obstructive pulmonary disease (COPD) who, while on the lung transplantation waiting list, received such a call. Complete transplant work-up, including cardiac tests undertaken shortly before, had revealed no contraindication to lung transplantation. She was admitted with severe acute respiratory failure, and her extensive work-up was compatible with pulmonary edema due to takotsubo cardiomyopathy. The lung transplantation was thus cancelled, owing to the patient's health condition and the poor quality of the graft as well. The patient stayed in the intensive care unit for several days, requiring noninvasive ventilation. The left ventricular function recovered completely within 10 days postdiagnosis, and the patient was discharged 13 days after her admission. The patient was transplanted 1 month thereafter, without any particular problems; she is currently, 8 months post-transplantation, in good condition. In the given case, the call for lung transplantation could have generated emotional stress severe enough to lead to takotsubo cardiomyopathy.

Evaluation of a new laboratory model for pulp healing: preliminary study.

AIM: To assess the feasibility of using the mouse as an in vivo model for studying pulpal healing in response to restorative procedures. METHODOLOGY: Direct pulp capping on maxillary first molar teeth with mineral trioxide aggregate (MTA), overlaid with light-cured composite resin, was performed on nineteen 3-month-old mice. For control teeth, the composite resin was placed in direct contact with the pulp. Animals were killed at 3 days, 1 week, 2 weeks, 5 weeks and 11 weeks postoperatively. Extracted dental tissues were subsequently analysed by haematoxylin and eosin staining, immunohistochemistry for dentine sialophosphoprotein (DSPP) expression, scanning electronic microscopy and X-ray analysis to determine both pulpal response and dentine bridge formation. RESULTS: Of the 19 mice initially used, 16 were subsequently studied. Histological analyses of pulps directly exposed to MTA for up to 2 weeks demonstrated a distinct structural change in the extracellular matrix. By weeks 5 and 11, a dentine bridge was present in all MTA-treated specimens in which DSPP immunoreactivity was clearly apparent. Scanning electronic microscopy and X-ray analysis enabled confirmation of calcification of the dentine bridge, and demonstrated that it had a globular surface morphology as opposed to the tubular appearance associated with orthodentine. CONCLUSIONS: This is the first description of the utilization of a murine model for study of in vivo pulpal repair. This approach provides a novel opportunity to enable the use of genetically modified animals to explore cellular and molecular processes during reparative events.

Prediction of beef carcass and meat quality traits from factors characterising the rearing management system applied during the whole life of heifers.

In this study, four prediction models were developed by logistic regression using individual data from 96 heifers. Carcass and sensory rectus abdominis quality clusters were identified then predicted using the rearing factors data. The obtained models from rearing factors applied during the fattening period were compared to those characterising the heifers' whole life. The highest prediction power of carcass and meat quality clusters were obtained from the models considering the whole life, with success rates of 62.8% and 54.9%, respectively. Rearing factors applied during both pre-weaning and fattening periods influenced carcass and meat quality. According to models, carcass traits were improved when heifer's mother was older for first calving, calves ingested concentrates during pasture preceding weaning and heifers were slaughtered older. Meat traits were improved by the genetic of heifers' parents (i.e., calving ease and early muscularity) and when heifers were slaughtered older. A management of carcass and meat quality traits is possible at different periods of the heifers' life.

Host and bacterial determinants of initial severity and outcome of Escherichia coli sepsis.

A 1-year prospective cohort study of all episodes of Escherichia coli bacteraemia in two French university hospitals was conducted to assess simultaneously the influence of host and bacterial determinants on the initial severity and outcome of E. coli sepsis. Clinical data (community-acquired/nosocomial infection, immune status, underlying disease, primary source of infection, severity sepsis scoring and outcome), phylogenetic groups (A, B1, D and B2), nine virulence factors (VFs) (papC, papGII, papGIII, sfa/foc, hlyC, cnf1, iucC, fyuA and iroN) and the antibiotic susceptibility of isolates were investigated. All VFs except iucC were significantly more prevalent (p <0.05) among the B2 group isolates. The non-B2 isolates were more frequently resistant to antibiotics than were B2 isolates (p <0.05). There were significantly more B2 isolates from immunocompetent than from immunocompromised patients (p <0.05). No bacterial or host determinants influenced the initial severity of sepsis. Multivariate analysis revealed that the presence of papGIII, septic shock at baseline and a non-urinary tract origin of sepsis were associated independently with a fatal outcome (p 0.04, <0.0001 and 0.04, respectively). A factorial analysis of correspondence allowed two populations of isolates to be distinguished: those belonging to the B2 group were associated more frequently with susceptibility to antibiotics, community-acquired infection, a urinary tract origin and immunocompetent hosts; those belonging to the A, B1 or D groups were associated more frequently with resistance to antibiotics, a nosocomial origin, a non-urinary tract source and immunocompromised hosts. Although no influence of host or bacterial determinants on the initial severity of sepsis was detected, bacterial and host determinants both influenced the outcome of E. coli sepsis significantly.

Relationships between thyroid status, tissue oxidative metabolism, and muscle differentiation in bovine fetuses.

The temporal relationships between thyroid status and differentiation of liver, heart and different skeletal muscles were examined in 42 bovine fetuses from day 110 to day 260 of development using principal component analysis of the data. Plasma concentrations of reverse-triiodothyronine (rT(3)) and thyroxine (T(4)) increased during development from day 110 to day 210 or 260, respectively, whereas concentration of triiodothyronine (T(3)) and hepatic type-1 5'-deiodinase activity (5'D1) increased from day 180 onwards. On day 260, high T(4) and rT(3) and low T(3) concentrations were observed together with a mature 5'D1 activity. Cytochrome-c oxidase (COX) activity expressed per mg protein increased at day 180 in masseter and near birth in masseter, rectus abdominis and cutaneus trunci muscles (P<0.05). Significant changes in citrate synthase (CS) activity per mg protein were observed between day 110 and day 180 in the liver and between day 210 and day 260 in the liver, the heart and the longissimus thoracis muscle (P<0.05). Muscle contractile differentiation was shown by the disappearance of the fetal myosin heavy chain from day 180 onwards. A positive correlation (r>0.47, P<0.01) was shown between thyroid status parameters (5'D1, concentrations of T(4) and T(3)) and COX activity in muscles known to be oxidative after birth (masseter, rectus abdominis) but not in liver and heart, nor in muscles known to be glycolytic after birth (cutaneus trunci, longissimus thoracis). A similar correlation was found between thyroid parameters and CS activity in liver and masseter. Results indicate that elevation of plasma T(3) concentrations in the last gestational trimester could be involved in the differentiation of oxidative skeletal muscles.

Muscle and meat quality characteristics of Holstein and Salers cull cows.

Muscle characteristics and sensory rating of meat were determined in M. longissimus thoracis (LT), M. semimembranosus (SM), M. semitendinosus (ST) and M. triceps brachii (TB) from seven Holstein (HO, dairy breed) and six Salers (SA, beef breed) cull cows slaughtered at 6-7 years of age at the same fat score. Significant differences (P<0.001) among muscle types were observed: ST was the more glycolytic and TB the more oxidative; total collagen: ST>SM=TB>LT; initial and overall tenderness: LT>TB=SM>ST, juiciness: TB>LT=SM>ST. Flavour differed only between breeds: HO>SA (P<0.01). Three tenderness classes (high, intermediate, low) were determined from scores for sensory overall tenderness for all 52 meats: the lower total and insoluble collagen contents, the more oxidative metabolism, the more tender was the meat. Muscle type, and not breed explained most of the variability of meat quality from dairy and beef cull cows slaughtered at the same age and fat score.

Effect of age and carcass weight on quality traits of m. rectus abdominis from Charolais heifers.

In practice cattle may be slaughtered at different combinations of age and weight. As each of these factors could affect meat quality traits, the present work aimed to identify which combination can be expected to increase overall meat quality of m. rectus abdominis of Charolais heifers. Totally, 40 heifers were slaughtered either at 26±1 or at 36±1 months of age. Young heifers were sampled at two different carcass weights (349±12 and 394±8 kg). Old heifers were also sampled at two different carcass weights (397±6 and 451±9 kg). The m. rectus abdominis was excised 24 h postmortem to determine metabolic enzyme activities, myosin heavy-chain isoform proportions, lipid contents, collagen content and collagen solubility. Shear force measurements were evaluated on raw and broiled meat after 14 days of ageing. Meat quality traits scored between 0 and 10 by sensory analysis. Increasing slaughter age from 26 to 36 months had no impact on either raw/broiled shear force (0.31⩽P⩽0.47) and/or meat quality traits (0.62⩽P⩽0.91) or on physicochemical properties of heifer's meat samples. Increasing carcass weight for a similar slaughter age of 26 months had also impact neither on meat quality traits (0.52⩽P⩽0.91) nor on muscular properties. On the contrary, increasing carcass weight for a similar slaughter age of 36 months had induced a decrease of muscular shear force (raw muscle; P=0.009) and a concomitant decrease of total collagen content (P=0.03). Nevertheless, no significant impact on meat quality traits was revealed by the sensorial panel (0.13⩽P⩽0.49). Metabolic enzyme activities (0.13⩽P⩽0.86) and myosin heavy-chain proportions (0.13⩽P⩽0.96) were not significantly impacted by slaughter age and carcass weight. Thus, the impact of increasing carcass weight and/or slaughter age in young Charolais heifers has a limited impact on meat quality traits and associated muscular characteristics. Modulating heifer's cycles (age and/or carcass weight in the studied range) appears to be a way to answer to the numerous marketing chains, without penalising meat quality traits.

Biochemical and organoleptic characteristics of muscle from early and late maturing bulls in different production systems.

In grass-based beef production systems (PS), early maturing (EM) breed types may be preferable to late maturing (LM) breed types in achieving adequate carcass fat cover. Biochemical and organoleptic characteristics of muscle from suckler bulls were investigated in EM and LM (n=28/breed) assigned to one of two PS (ad libitum concentrates and grass silage to slaughter (C) or ad libitum silage plus 2 kg concentrate daily during winter followed by 99 days at pasture and then an indoor finishing period on C (GSPC)) in a 2 breed type×2 PS factorial arrangement of treatments. Bulls were managed to have a common target carcass weight of 380 kg. Intramuscular fat (IMF) content was higher (P<0.05) for EM than LM, and for C than GSPC bulls. Collagen solubility was higher (P<0.05) for C than GSPC bulls. Lactate dehydrogenase (LDH) and phosphofructokinase activities were higher (P<0.05) for LM than EM. Isocitrate dehydrogenase activity and the Type I myosin heavy chain (MyHC) proportion were higher (P<0.05) for EM than LM. The LDH activity and the Type IIX MyHC proportion were higher (P<0.05) for C than GSPC bulls. Sensory ratings for tenderness and juiciness were higher (P<0.01) for beef from EM than LM while sensory ratings for tenderness, flavour liking and overall liking were higher (P<0.001) for C than for GSPC bulls. Differences in sensory quality were largely eliminated when adjusted for IMF. Overall, carcass fat scores, IMF and sensory scores were higher in EM than LM and in C than GSPC bulls but most differences in sensory quality could be attributed to differences in IMF.

Effect of a grazing period prior to finishing on a high concentrate diet on meat quality from bulls and steers.

Bulls and steers (n=60) were assigned to a pre-finishing grazing period and subsequently finished on concentrates or offered concentrates without grazing until slaughter (19months). Colour and pH of longissimus thoracis were measured (48h post-slaughter), and samples collected for proximate composition, collagen, sarcomere length, muscle fibre and enzymatic profile analysis. Steaks for texture, cook loss and sensory were aged (14days). Castration increased intramuscular fat content, cook loss and myosin isoforms IIa and I proportions, and decreased IIx proportion (P<0.05). Steer meat was positively correlated to overall tenderness, texture and acceptability (P<0.05). The presence of a pre-finishing grazing period decreased intramuscular fat and increased the proportion of IIa compared with animals on concentrates, while no differences were found in sensory. Muscle colour, collagen, sarcomere length and instrumental texture were not modified by diet or castration. In conclusion, beef sensory characteristics were unaffected by diet, whereas castration resulted in a small improvement; however all the treatments produced an acceptable product.