Rigor Development Research Articles

Advancing Endocrine Disruptors via In Vitro Evaluation: Recognizing the Significance of the Organization for Economic Co-Operation and Development and United States Environmental Protection Agency Guidelines, Embracing New Assessment Methods, and the Urgent Need for a Comprehensive Battery of Tests.

Efforts are being made globally to improve the evaluation and understanding of endocrine-disrupting chemicals. Recognition of their impact on human health and the environment has stimulated attention and research in this field. Various stakeholders, including scientists, regulatory agencies, policymakers, and industry representatives, are collaborating to develop robust methodologies and guidelines for assessing these disruptors. A key aspect of these efforts is the development of standardized testing protocols and guidelines that aim to provide consistent and reliable methods for identifying and characterizing endocrine disruptors. When evaluating the potential endocrine-disrupting activity of chemicals, no single test is capable of detecting all relevant endocrine-disrupting agents. The test battery approach is designed to reduce the risk of false negative results for compounds with toxic potential. A weight-of-evidence approach is therefore necessary for endocrine disruptor evaluation. This approach considers various types of data from multiple sources, assessing the overall strength, consistency, and reliability of the evidence. OECD guidelines are highly regarded for their scientific rigor, transparency, and consensus-based development process. It is crucial to explore and develop new methodologies that can effectively evaluate the risks associated with potential endocrine disruptors. Integrating these methods into a comprehensive weight-of-evidence framework will enhance risk assessments and facilitate informed decisions regarding the regulation and management of these substances, ensuring the protection of human health and the environment from their adverse effects.

Early postmortem beef muscle proteome and metabolome variations due to supranutritional zinc and ractopamine hydrochloride supplementation.

It was hypothesized that the longissimus thoracis (LT) muscle proteome, phosphoproteome, and metabolome could explain postmortem metabolism and tenderness differences in muscle from cattle supplemented zinc (Zn) and/or ractopamine hydrochloride (RH). High percentage Angus steers (N = 20) were fed in a 2 × 2 factorial assigned to Zn and RH treatments: control (CON; n = 10; analyzed 36mg Zn/kg dry matter [DM]) or supranutritional Zn supplementation (SUPZN; n = 10; control diet + 60mg Zn/kg DM [from ZnSO4] + 60mg Zn/kg DM [from Zn-amino acid complex]) for the entire 89-d trial. During the 28 d before harvest, steers were blocked by body weight within Zn treatments to RH treatments of 0 (NO; n = 10) or 300mg (RAC; n = 10) per steer per day. Steers were harvested at the Iowa State Meat Laboratory, where pH decline (1, 3, 6, and 24h postmortem) was measured. At 24h postmortem, LT muscle sections were removed from carcasses, and steaks were analyzed for Warner-Bratzler shear force (WBSF) values at 1, 3, 7, and 14 d postmortem. Muscle samples were taken at 1h, 1, 3, 7, and 14 d postmortem for the following analysis: troponin-T degradation (1, 3, 7, and 14 d postmortem), myosin heavy chain analysis (1h postmortem), sarcoplasmic proteome analysis through tandem mass tagging analysis (1h and 1 d postmortem), metabolome analysis (1h and 1 d postmortem), and phosphoproteome analysis (1h postmortem). SUPZN-NO tended to have a lower (P = 0.06) pH at 6h postmortem and a lower WBSF value (P = 0.06) at 1 d postmortem. CON-RAC had a higher (P = 0.04) pH at 6h postmortem and WBSF value (P < 0.01) at 1 d postmortem. A lower pH at 6h postmortem and lower WBSF value at 1 d postmortem in the SUPZN-NO treatment was accompanied by more sorbitol and fructose at 1 d postmortem, and less myosin regulatory light chain 2 at 1h postmortem, and less adenosine monophosphate deaminase 1 (AMPD1) at 1 d postmortem than all other treatments. A higher pH at 6h postmortem and higher WBSF value at 1 d postmortem in CON-RAC and SUPZN-RAC was accompanied by more soluble structural proteins (troponin-T and myosin-7) at 1h postmortem than CON-NO. At 1h postmortem, CON-RAC had more glyceraldehyde-3-phosphate dehydrogenase than CON-NO or SUPZN-RAC. Differences in energy metabolism enzymes, metabolites, and structural proteins may affect ATP production, rigor development, and lactate buildup which may explain the differences in postmortem metabolism and tenderness development at 1 d postmortem.

Thaw rigor in Atlantic salmon (Salmo salar) fillets, as affected by thawing rate and frozen storage time

The influence of stress, storage time and thawing regimes was investigated with respect to rigor development and other related physical traits, on farmed Atlantic salmon. The fish were sampled from a commercial slaughterhouse production line, filleted, vacuum packaged and quickly frozen, pre-rigor. The investigated parameters were selected to maintain fresh-like quality.No significant (p > 0.600) effects were seen between rigor contraction and stress parameters measured at time of slaughter. Frozen storage time significantly (p = 0,003) affected contraction, while no effect of thawing method (p = 0.824) was detected. The liquid loss of the frozen groups was significantly (p = 0.019) affected by thawing method, while frozen storage time had no significant (p = 0.087) effect. Further, drip loss was not affected by fillet contraction (p = 0.075). Increasing frozen storage time significantly (p = 0.042) decreased the redness and thawing in air rather than water significantly (p = 0.015) decreased the yellowness of the fillets. Fillet stored for 1 month had significantly (p = 0.004) lower F-break force, while no significant (p > 0.227) effect of storage or thawing was seen on hardness. Frozen fillets were comparable to 7 days old vacuum packaged fresh fillets stored on ice for seven days, albeit with some increase in drip loss and some differences in texture, but with comparable color and fillet contraction.

Rigor development and meat quality of Murrah buffalo from different production systems

The purpose of this study was to evaluate the rigor mortis development and its effects on striploins quality of Murrah buffalos from meat (males) and dairy (females) productions. The rigor was monitored during carcass chilling (up to 22 h postmortem) and the meat physicochemical traits was accessed after 72 h postmortem. Glycolytic rate, measured by decreasing pH and glycogen content, was higher (p &lt; 0.05) in female than in male buffalo, leading to a different onset rigor time (5-6 h and 9-10 h, respectively). Male meat had (p &lt; 0.05) lower fat (1.41 vs 3.58%) and insoluble collagen (1.18 vs 1.58 mg g-1) contents, but higher soluble collagen content (5.16 vs 20.38%), sarcomere length (1.65 vs 1.84 µm), myofibrillar fragmentation (334 vs 295) and shear force (39.38 vs 25.92 N) than females. These results suggest that dairy buffalo meat is more tender and can be used on the market as high-quality meat such as from buffalo raised to meat production.

Longitudinal vibration interferes with cross-bridge attachment and prevents muscle fibre shrinkage under PSE-like conditions

The impact of longitudinal vibration on cross-bridge attachments between myofilaments was investigated in single fibres and intact muscle. Sinusoidal length vibration (frequency 50 Hz, amplitude 5% of fibre length) reduced active force by 40% when fibres were activated by elevation of [Ca2+], but did not alter the force when fibres were in rigor state. When vibrated for 30 min in rigor at pH 5.5 and 38 °C (PSE conditions), the lateral shrinkage of the fibres was significantly reduced, suggesting a potential positive influence of vibration on water-holding capacity. In whole muscle incubated at 38 °C until 8 h post mortem, the progress of rigor onset was accessed by measuring the increase in muscle stiffness. Vibration applied 3-5 h post mortem postponed rigor development, but did not have significant influence on water-holding capacity compared with non-vibrated conditions. In conclusion, the results suggest that muscle vibration can be a future technique to delay rigor development and prevent muscle fibre shrinkage and PSE development after slaughter.

Does teaching rigorously really enhance undergraduates’ intellectual development? The relationship of academic rigor with critical thinking skills and lifelong learning motivations

While previous research has examined outcomes related to academic rigor, mixed findings have resulted from differing conceptualizations of rigor as well as varying methodological approaches. Defining rigor as those in-class practices and assignments that require students to engage in deep learning and demonstrate cognitive complexity, we use longitudinal student-level data from 46 four-year institutions in the USA to examine the relationship of academic rigor with undergraduate development of critical thinking skills and two aspects of self-motivated learning (need for cognition and positive attitudes towards literacy). We find that academic rigor is positively related to both aspects of self-motivated learning at the end of the first year of college, with an advantage for students who enter college with low ACT scores and those with less positive attitudes about reading and writing. Rigor is positively related to all three outcomes at the end of the fourth year, with the magnitude of these relationships tending to increase from the first year to the fourth year. Further, by disaggregating the composite measure of rigor into subscales that separate rigorous in-class practices from rigorous exams and assignments, we find that the relationship between rigor and intellectual development is sometimes driven by one form of rigorous practice, with in-class rigor especially benefitting the critical thinking skills of first-generation students. These findings have important implications for instructors, administrators, and scholars in higher education.

Novel localization algorithm for wireless sensor network based on intelligent water drops

High localization rigor and low development expense are the keys and pivotal issues in operation and management of wireless sensor network. This paper proposes a neoteric and high efficiency algorithm which is based on new optimization method for locating nodes in an outdoor environment. This new optimization method is non-linear optimization method and is called intelligent water drops (IWDs). It is proposed that the objective function which need to be optimized by using IWDs is the mean squared range error of all neighboring anchor nodes. This paper affirms that received signal strength indicator (RSSI) is used to determine the interior distances between WSNs nodes. IWDs is an elevated performance stochastic global optimization tool that affirms the minimization of objective function, without being trapped into local optima. The proposed algorithm based on IWDs is more attractive to promote elevated localization precision because of a special features that is an easy implementation of IWDs, in addition to non cost of RSSI. Simulation results have approved that the proposed algorithm able to perform better than that of other algorithms based on optimization techniques such as ant colony, genetic algorithm, and particle swarm optimization. This is distinctly appear in some of the evaluation metrics such as localization accuracy and localization rate.

University Faculty Beliefs About Emergent Multilinguals and Linguistically Responsive Instruction

Internationalization trends worldwide have brought more multilingual students into English‐medium university classrooms in the United States and elsewhere. Faculty across the disciplines increasingly have the dual challenge of developing both content and advanced academic language. Ample precedent in P–12 education suggests developing instructors’ knowledge of (a) students as language learners, (b) instructional techniques grounded in second language acquisition theory, and (c) contextual factors necessary for helping instructors implement linguistically responsive instruction (LRI). This study probes the extent to which prior work transfers to the tertiary setting, focusing on participating faculty members’ beliefs about multilingual students, LRI, and context. The authors collected survey data from 197 faculty at a mid‐size comprehensive university in the midwestern United States and analyzed written comments provided by participants. They found that, on the whole, faculty participants displayed deficit views regarding students’ linguistic and academic abilities and questioned the appropriateness and feasibility of several of the LRI techniques. Many rejected the notion that language instruction was within the scope of their responsibilities and expressed a strong preference for support provided outside of class time. The authors discuss the results in terms of the notions of rigor, college readiness, and faculty development in LRI.

Seasonal Changes in Rigor Development and Flesh Texture of Wild Japanese Sea Bass (Lateolabrax japonicus)

ABSTRACTThe season for finding the firmest sashimi made from wild Japanese sea bass was investigated. Flesh rigor tension and contraction were measured by a “new” device with isometric (muscle length kept constant) and isotonic (balance beam moves freely) transducers. Both flesh rigor tension and contraction peaks appeared at the same postmortem times, with attainment of ultimate pH and adenosine triphosphate/inosine monophosphate ratio in four seasons. Seasonal seawater temperature correlated negatively to seasonal maximum rigor contraction and positively to seasonal flesh breaking strength at 72 h postmortem. After rigor peak tension attainment, the tension relaxation was much lower than that of other wild fish species, especially in summer. The sea bass muscle resisted structure disruption in rigor isometric tension generation. Wild sea bass sashimi was firmest in breaking strength in summer.

“No Excuses” in New Orleans: The Silent Passivity of Neoliberal Schooling

Drawing on ethnographic data, this article critically analyzes pedagogy in “no excuses” charter schools in New Orleans. Employing Ladson-Billings's framework for culturally relevant pedagogy, the author describes the level of academic rigor, cultural competence, and critical consciousness development across classrooms. This study provides empirical evidence that within a market-based system, the purpose of schooling shifts toward the production of assessment data at the expense of culturally relevant practices.

Post mortem rigor development in the Egyptian goose (Alopochen aegyptiacus) breast muscle (pectoralis): factors which may affect the tenderness.

Baseline research on the toughness of Egyptian goose meat is required. This study therefore investigates the post mortem pH and temperature decline (15 min-4 h 15 min post mortem) in the pectoralis muscle (breast portion) of this gamebird species. It also explores the enzyme activity of the Ca(2+)-dependent protease (calpain system) and the lysosomal cathepsins during the rigor mortis period. No differences were found for any of the variables between genders. The pH decline in the pectoralis muscle occurs quite rapidly (c = -0.806; ultimate pH ∼ 5.86) compared with other species and it is speculated that the high rigor temperature (>20 °C) may contribute to the increased toughness. No calpain I was found in Egyptian goose meat and the µ/m-calpain activity remained constant during the rigor period, while a decrease in calpastatin activity was observed. The cathepsin B, B & L and H activity increased over the rigor period. Further research into the connective tissue content and myofibrillar breakdown during aging is required in order to know if the proteolytic enzymes do in actual fact contribute to tenderisation.

Advancing the Microbiome Research Community

The human microbiome has become a recognized factor in promoting and maintaining health. We outline opportunities in interdisciplinary research, analytical rigor, standardization, and policy development for this relatively new and rapidly developing field. Advances in these aspects of the research community may in turn advance our understanding of human microbiome biology.

Professors are Not Elderly: Evaluating the Evidential Value of Two Social Priming Effects Through P-Curve Analyses

It is possible that the number of false positives in the literature is much greater than is desirable due to a combination of low statistical power, publication bias, and flexibility when analyzing data. Recently, some researchers have argued the replicability crisis social priming research is greatly exaggerated (Dijksterhuis, 2014; Stroebe & Strack, 2014). To quantify the extent to which researcher degrees of freedom are a real problem, I present two p-curve analyses that examine the evidential value of research lines on professor priming and elderly priming. The results indicate studies examining elderly priming are p-hacked, while studies examining professor priming contain evidential value. I believe a polarized discussion about whether social priming is true or not, whether direct replications or conceptual replications are preferable, or whether methodological rigor or theory development is needed is unlikely to lead to scientific progress. Instead, we have to meta-analytically evaluate individual effects based on their evidential value, and collaboratively examine what is likely to be true.

Effect of post-mortem handling conditions on the quality of spent hen meat curry

Study was performed to determine the effect of post-mortem handling conditions on the physico-chemical and sensory attributes of spent hen meat curry. Breast cuts of spent hens were subjected to different postmortem handling conditions before cooking viz; made into small cuts and cooked within 1-2h of slaughter (condition1), made into small cuts and cooked after 4-5h of slaughter (condition2), made into small cuts immediately after slaughter, stored at 4 ± 1°C for 12h and then cooked (condition3), stored at 4 ± 1°C for 12h, made into small cuts and cooked (condition4). The pH of meat just before cooking due to different stages of rigor development under various conditions differed accordingly. Observed differences in temperature of meat just before cooking were because of different postmortem handling condition variations viz:1,2,3,&4. The associated post mortem changes under different postmortem handling conditions before cooking led to significant variation in Water holding capacity, Water Soluble Protein, Salt Soluble Protein, cooking yield, moisture percentage before cooking and after cooking and also WB shear force value. In general, sensory scores were higher for conditions4 and 1 as compared to conditions2 and 3. Results revealed that quality attributes of spent hen meat curry can be improved by following proper post-slaughter handling and processing conditions. To get meat curry of good sensory quality, meat should be cooked preferably within 1-2h of slaughter or after 10-12h of storage of intact carcass at 4 ± 1°C. Cuts should be made just before cooking but cooking after 4-5h of slaughter should be avoided.

Effect of pre-slaughter procedures on stress responses and some quality parameters in sea-farmed rainbow trout ( Oncorhynchus mykiss)

The aim of this study was to investigate the effects of pre-slaughter procedures on stress responses and flesh quality in sea-farmed rainbow trout ( Oncorhynchus mykiss) . A total of 114 fish were slaughtered 1) at the farm, 2) after transport, 3) after 4 days in the holding cage and then 30–50 min crowding, 4) after pumping, 5) after pumping and electrical stunning, 6) after 4 h crowding and 7) after 4 h crowding and pumping. Blood samples were collected from the fish at consecutive pre-slaughter stages. The time course of r igor mortis was evaluated for 72 h post mortem. Fillet cuts were evaluated for such quality parameters as gaping and weight loss after ice or frozen storage. The results show that, in most cases, blood cortisol, lactate and pCO 2 levels increased while blood pH and pO 2 decreased according to the number of events added to the slaughter process. A significant increase in hematocrit and blood glucose after transportation was observed. Both crowding and pumping led to acceleration in onset of rigor mortis, whereas transportation and electrical stunning did not show any significant effect on rigor development. The severity of gaping and the degree of weight loss were not significantly affected by fish pumping and electrical stunning. We conclude that pre-slaughter procedures such as crowding and pumping cause stress and affect flesh quality accelerating the onset of rigor mortis in sea-farmed rainbow trout.

Introduction to the Special Section

In a span of merely 10 years, the school counseling profession has reinvented itself. Since the late 1990s, school counseling has progressed from the tradition of a responsive services focus to a proactive and programmatic system that is inextricably integrated with the mission of schools. The national standards of the American Counselor Association (ASCA, 1997; Campbell & Dahir, 1997), the Transforming Counseling Initiative (Education Trust, 1997), and the ASCA (2003, 2005) National Model have directed school counselors to respect the past and embrace the present but forge a new vision to the future. The challenges facing students and 21st-century schools have influenced the paradigms and practices that forward the profession and place a renewed emphasis on supporting student achievement, social justice advocacy, and school counselor accountability. * We Are in Charge of Our Destiny The imperative of any professional organization is to choose with intentionality how to lead the organization and propel its members forward by anticipating what the future may hold and establish a foundation to shape its destiny. Theobald suggested that we need to envision the society we really want and to develop a plan to move from the present into the future that we choose to shape (Maples, 1984). More than 20 years ago, Inbody (1984) identified six basic premises that were critical to the future of school counseling: 1. What the school counseling profession does today wild have an impact on the quality of the field of school counseling and educational environments in which school counselors and students must live. 2. Scientific methods of researching school counseling can be used for anticipating the various futures school counselors could create unknowingly. 3. There is no longer just one future that awaits the school counseling profession but many different possible futures, depending on what school counselors and the profession choose today. 4. counselors assume a moral urgency in their responsibility to future generations of students and school counselors. 5. Technology continues to serve as a powerful tool for school counselors; however, school counselors are responsible for technology integration and use in the future in a way that may have been inconceivable 20 years ago. 6. Prior to unleashing the power of an idea on the school counseling profession and students, an extensive study of the future impact of that idea must be mounted. (adapted from pp. 216-217) Despite the passage of more than 2 decades, these premises still ring true. The purpose of this special section, School Counseling in the 21st Century: Where Lies the Future? is not to dwell on the past but to ponder the next wave of innovation that will forward the profession. The contributors have worked with the assumption that the ASCA (2003, 2005) National Model and the Transforming Counseling model (Education Trust, 1997) will become firmly embedded themselves in the hearts and minds of the 100,000 school counselors in public schools. In our crystal ball, 21st-century school counselors are in a powerful and pivotal position to effectively demonstrate how the complement of academic rigor and affective development is the formula to student success (Stone & Dahir, 2006). They recognize and embrace the critical part they play as key members of the educational leadership team and rise to the challenge to share in the responsibility of preparing students to meet the expectations of higher academic standards while assisting them to become productive and contributing members of society. Counselor educators, practitioners, and future school counselor candidates for degrees have established a new way of work as leaders, collaborators, advocates, and systemic change agents in concert with the dynamics of the educational landscape, the globalization of society and economics, and the plethora of diverse student needs. …

Effects of &lt;i&gt;post mortem&lt;/i&gt; temperature on rigor tension, shortening and pH in ostrich muscle

Fully developed rigor mortis in muscle is characterised by maximum loss of extensibility. The course of post mortem changes in ostrich muscle was studied by following isometric tension, shortening and change in pH during the first 24 h post mortem within muscle strips from the muscularis gastrocnemius, pars interna at constant temperatures of 7 °C and 37 °C. Maximum shortening was significantly higher at 37 °C (33.4 ± 3.57%) than at 7 °C (10.7 ± 2.63%). The rate of rigor development was temperature dependent, reaching a maximum tension at 4.08 ± 3.89 h post mortem in muscle strips at 37 °C; while at 7 °C maximum tension was reached at 10.5 ± 6.47 h post mortem. It was concluded that the completion of rigor occurred at the point of minimum pH. Keywords: Rigor mortis, rigor tension, muscle shortening, ostrich, rigor shortening, cold-shortening, hot-deboning, rate of pH declineSouth African Journal of Animal Science Vol. 38 (3) 2008: pp. 184-192

Impact of starvation and handling stress on rigor development and quality of Atlantic salmon ( Salmon salar L)

Farmed Atlantic salmon ( Salmo salar L) were fed to satiation or starved for 35 d, and subjected to acute pre-slaughter stress or careful handling before slaughtering. Rigor development, post-mortem energy metabolism and quality variations were analysed during 72 h cold storage. The body weight averaged 2.9 and 3.5 kg of the fed and starved salmon, respectively. The starved salmon had lower condition factor (0.99 vs. 1.11) and higher slaughter yield (92.6 vs. 87.5%), but the fat content was similar (11.8–12.9%) in the fed and starved salmon. The initial glycogen level was lower in the starved salmon (21 vs. 29 μmol g − 1 ), whereas initial ATP levels (6.4–6.6 μmol g − 1 ) were not affected by starvation. Pre-slaughter stress accelerated rigor development, stimulated lactate formation through post-mortem glycolysis, and increased the breakdown of ATP and CP. The effect of stress on rigor development was less pronounced in starved salmon, and a significant interaction was observed between nutritional status and stress. Rigor development was closely correlated to ATP breakdown, especially in fillets. Acute stress accelerated flesh softening during ice storage. After 72 h storage, the fillets of the starved salmon exposed to careful slaughter handling had the significantly firmest texture, whereas the most intense fillet colour was observed in the starved/stressed salmon. Liquid leakage from the muscle during cold storage was lower in the starved salmon, but pre-slaughter stress had no significant impact. It is concluded that a starvation period of five weeks can improve the resistant to acute stress prior to slaughtering of Atlantic salmon that in turn hampers rigor development.

한국 소비자 쇠고기 연도 보증을 위한 도축후 도체 처리기술

쇠고기 연도 조절에 대한 연구는 오랜 역사를 가지고 있으나, 균일한 쇠고기 맛에 대한 소비자들의 요구 증가로 응용적 연구가 가속화 되고 있다. 도축 후 근절길이와 단백질 분해가 연도에 큰 영향을 미친다는 사실은 잘 밝혀졌다. 전기자극은 맛 보증 프로그램을 위해서 여러 나라에서 산업적으로 이용되고 있다. 전기자극이 연도를 향상(또는 질겨짐 감소)시키는 기전은 모두 밝혀지지 않았으나, 이 처리가 저온 단축을 막고 사후 강직을 단축시켜 단백질 분해를 증가시킨다는 결과는 명확해 보인다. 한편 Tenderstretch는 사후 강직기 동안 근섬유와 결체 조직에 장력을 가하여 고기의 질겨짐을 줄이는 작용을 하는 것으로 보인다. 선행 연구들은 도축 후 전기자극과 Tenderstretch 처리가 지방이 많은 가축과 냉각 온도가 느린 조건에서도 연도를 향상 시킨다는 사실들을 증명하였다. 최근 연구에 의하면 한국 소비자들도 연도가 쇠고기 맛을 결정하는데 중요한 요인이며, 국내 연구결과에 의하면 도축 후 전기자극 또는 tenderstretch 처리가 한우의 연도 및 육색을 증가시키는 것으로 나타났다. 특히 이 기법들은 도체의 크기 및 지방 침착도와 도축 후 냉각속도 조절이 어려운 국내 축산업 조건에서 연도의 균일성 및 개선을 보장할 수 있는 중요한 기법으로 판단되나, 국내 산업체에서는 이용되지 않고 있다. 이 논문은 이러한 기법에 대한 현재의 이론과 국내 쇠고기 산업에 주는 의미를 서술했다. Management to improve beef tenderness is always been a historical idea, but during the recent past it has become an issue of prime importance to the meat scientists and the industries as well. Variation in tenderness is the prime explanation for consumer’s dissatisfaction for the concern meat. It has been well documented that both postmortem proteolysis and sarcomere length have significant effect on meat tenderness and its consistency. Electrical stimulation and tenderstretch techniques have been used by a number of countries to underpin carcass quality assurance schemes focused on eating quality. The mechanism(s) by which the postmortem interventions improve tenderness (or prevent toughness) has not been fully elucidated. However, it is evident that electrical stimulation accelerates the development of rigor mortis so that prevention of cold shortening is possible and ageing commences at higher temperatures. On the other hand, tendersretch appears to prevent meat toughness via placing tension of the myofibrils and connective matrix during rigor development. Previous findings indicated that electrical stimulation and tenderstretch improved beef tenderness even for fattened cattle under moderate chilling conditions. Recent studies demonstrate beef tenderness to be one of the most important factors determining satisfaction levels of Korean beef consumers. There are number of studies which reported that electrical stimulation and tenderstretch techniques improved Hanwoo tenderness and color. It is believed that the techniques are mostly useful wherein controls of carcass size, fatness and/or chilling regimes are not easy such as Korean beef industry. However, Korean beef industry is one such area where postmortem intervention techniques have not been adopted so far. Taking into consideration of the Korean beef industry, wherein carcass size and fatness varies the post-slaughter intervention technique could be the most feasible measurement to ensure eating quality. The manuscript attempts to highlight the current knowledge aiming primarily towards the assurance of beef tenderness.

Cardioprotection Via Activation of Protein Kinase C-δ Depends on Modulation of the Reverse Mode of the Na + /Ca 2+ Exchanger

Pretreatment with the volatile anesthetic sevoflurane protects cardiomyocytes against subsequent ischemic episodes caused by a protein kinase C (PKC)-delta mediated preconditioning effect. Sevoflurane directly modulates cardiac Ca2+ handling, and because Ca2+ also serves as a mediator in other cardioprotective signaling pathways, possible involvement of the Na+/Ca2+ exchanger (NCX) in relation with PKC-delta in sevoflurane-induced cardioprotection was investigated. Isolated right ventricular rat trabeculae were subjected to simulated ischemia and reperfusion (SI/R), consisting of superfusion with hypoxic glucose-free buffer for 40 minutes after rigor development, followed by reperfusion with normoxic glucose containing buffer. Preconditioning with sevoflurane before SI/R improved isometric force development during contractile recovery at 60 minutes after the end of hypoxic superfusion (83+/-7% [sevo] versus 57+/-2% [SI/R];n=8; P<0.01). Inhibition of the reverse mode of the NCX by KB-R7943 (10 micromol/L) or SEA0400 (1 micromol/L) during preconditioning attenuated the protective effect of sevoflurane. KB-R7943 and SEA0400 did not have intrinsic effects on the contractile recovery. Furthermore, inhibition of the NCX in trabeculae exposed to sevoflurane reduced sevoflurane-induced PKC-delta translocation toward the sarcolemma, as demonstrated by digital imaging fluorescent microscopy. The degree of PKC-delta phosphorylation at serine643 as determined by western blot analysis was not affected by sevoflurane. Sevoflurane-induced cardioprotection depends on the NCX preceding PKC-delta translocation presumably via increased NCX-mediated Ca2+ influx. This may suggest that increased myocardial Ca2+ load triggers the cardioprotective signaling cascade elicited by volatile anesthetic agents similar to other modes of preconditioning.