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This paper proposes an end-to-end deep learning framework, termed as motion-aid feature calibration network (MFCN), for video object detection. The key idea is to leverage on the temporal coherence of video features while considering their motion patterns as captured by optical flow. To boost detection accuracy, the framework aggregates the calibrated features both at pixel and instance levels across frames to achieve improved robustness despite appearance variations. The aggregation and calibration are efficiently and adaptively conducted based on an integrated optical flow network. Meanwhile, the entire architecture of the proposed method is end-to-end, thus significantly improving its training and inference efficiency when compared to multi-stage methods for video object detection. Evaluations on KITTI and ImageNet VID indicate that MFCN can improve the results of a strong still-image detector by 11.2% and 7.31% respectively. MFCN also outperforms other competitive video object detectors and achieves a better trade-off between accuracy and runtime speed, demonstrating its potential for use in autonomous driving systems.

Despite the increasing popularity of mobile applications in commerce, there exists an emerging trend where users are abandoning these applications due to the abuse of push notification. This study applies the stress-coping theory to investigate this phenomenon. A 2 × 2 × 2 factorial design experiment with manipulations on perceived information overload, perceived intrusiveness, and perceived reward is conducted in this study. The results show that users are affected by perceived information overload and perceived intrusiveness from push notifications in shopping applications and they deal with these stresses by using disturbance handling strategies and self-preservation strategies. The application varies with different reward systems. Specifically, high levels of reward can encourage disturbance handling strategies and decrease self-preservation strategies. In addition, with high perceived information control and self-efficacy in using mobile devices, users prefer to take actions to handle the disturbances. Finally, disturbance handling strategies prohibit discontinuance behavior, whereas self-preservation strategies encourage quitting behavior. The results of this study benefit both mobile shopping apps users who are in danger of stressors to develop proper strategies and actions to protect themselves and retailers who use applications on smartphones to provide products and services to obtain access to users more efficiently.

Despite prevalent privacy and security threats on the cloud, users have put tremendous amounts of their personal information on cloud storage. This present study proposes a comprehensive research framework to investigate cloud storage users' willingness to put personal information on personal cloud-based storage applications. Our research framework is theoretically derived from the Communication Privacy Management Theory and Privacy-Trust-Behavioral Intention Model. To empirically test our research framework, we conducted an online survey of 786 active cloud storage users both in Indonesia and Taiwan. The findings suggest that cloud storage users' willingness to put personal information is highly influenced by trust, perceived costs, perceived benefits, and also the degree of sensitivity of the personal information. Some findings with regard to cultural differences between the two countries are also showed out. The key findings, implications, and limitations are discussed in this paper.

The newly issued International Financial Reporting Standards (IFRS) have significantly transformed the accounting process and the accounting information system (AIS). Confronting the changes in information technologies (IT), using the AIS appropriately is crucial to derive accurate information from which to process business transactions and report information in compliance with the new IFRS. Built on adaptive structuration theory (AST), this study is aimed toward investigating how accounting regulatory changes influence AIS use, which consequently affects accounting process performance. Data are collected through a questionnaire survey of 250 accountants from 36 countries currently using the IFRS as their accounting standards. The results show that perceived system restrictiveness, IT professional support, and accountant's self-efficacy significantly explain faithfulness of appropriation (FOA) whereas perceived effectiveness of controls on IT use does not. FOA influences exploitive and exploratory task adaptations, which subsequently predict accounting process performance under the new IFRS. This study enriches the AST literature and contributes to both the accounting and IT domains. Our findings provide organizations with new insights into how to maintain the efficiency of accounting practice and business operations under the new IFRS.

Little is known about the effectiveness of information strategies on energy conservation in developing countries. In this study, we conduct a field experiment in an apartment complex in India to test how information about electricity usage impacts the electricity consumption of urban middle class households. Our results, based on fifteen-minute electricity readings over an academic year, show that non-monetary messages that framed electricity consumption in terms of environmental and health impacts were more effective than messages emphasizing the monetary savings of reducing electricity consumption. Households in the environmental/health group accessed the online energy-monitoring dashboard more frequently and reduced their electricity usage by 18.4% relative to the control group. Households in the monetary group did not significantly alter their usage. These results about revealed preferences are contrasted with stated preferences disclosed in a survey of urban Indians who describe money, not health, as the main motivation for energy conservation. Our findings have important implications for the development non-monetary strategies for energy conservation in developing countries.

This study investigated the impact of two In-Vehicle Information Systems (IVISs) on both usability and driving safety. We simulated vehicle checkerboard and hierarchical IVIS interface layouts and examined their usability based on task completion time, error rate, NASA-TLX, and System Usability Scale (SUS). Our driving safety measures included mean glance time, mean number of glances, blink frequency, and heart rate while real driving. The driving performances of 24 participants were recorded and assessed in real driving tasks of four driving speeds (0, 30, 60, and 80 km/h). Our results show that task completion time, SUS, and mean number of glances were significantly different with the two layouts. Moreover, we observed that the two layouts varied in their impacts on usability and driving safety at the different speeds. The hierarchical layout was more efficient at the lower speeds of 0 and 30 km/h, while the checkerboard layout outperformed at the higher speeds of 60 and 80 km/h. This study offers empirical evidence for IVIS interface design.

We propose a simple method to measure a driver's fatigue state by detecting the driver's grip force on the steering wheel while driving. We tested the grip force of 36 drivers on the steering wheel in conscious states (Alert) and fatigue states under actual road driving conditions. Using the Stanford sleepiness scale (SSS), we divided drivers into Alert Group A, fatigue Group A, and fatigue Group B. During 20-min real-road driving trials, we measured the steering wheel grip force, electroencephalogram index (R = (α + θ)/β), and blink frequency of each driver synchronously. We found that ΔF, the difference between the maximum/minimum grip force and the standard deviation of the grip force, σF, for each driver, strongly correlated with the driver's fatigue state. In the fatigue state, both ΔF and σF increased significantly. We examined these force indices using analysis of variance (ANOVA) and validated them against the R-value, blink frequency, and the driver's self-reported fatigue state. Using the grip force in fatigue detection, our method can achieve an overall recognition rate of 86.6% and an individual recognition rate of 88.3%. These results indicate that this method can effectively detect a driver's fatigue state during actual road driving. This new method has several advantages, such as a high signal-to-noise ratio, simple data collection, and no influence on daily driving. Thus, our proposed method may provide a theoretical foundation for the development of fatigue-detecting steering wheels

Facebook users are increasingly using the site to conduct commercial activities, by posting advertisements in groups and then buying or selling items from each other. This type of group is called as a C2C Facebook "buy and sell" group in the current work. Drawing from latent state-trait theory, heuristic information processing, and observational learning, we conducted an online field experiment to empirically investigate the effect of the information quality of the advertisement, the trait of the impulsiveness, and the number of "likes" it receives on consumers' urge to buy impulsively. The findings and implications of our study are discussed in the paper.

• Critically-ill COVID-19 patients with New Delhi Metallo-beta-lactamase producing Enterobacterales infections at our medical center had poor outcomes, including death in 4 of 5 cases • Multiple insults contributed to the occurrence of co-infection in these patients, including prolonged hospitalization, intubation, invasive devices, extensive antibiotic use, immunosuppressive therapy and environmental factors • There are few antibiotic options for treatment of infections with New Delhi Metallo-beta-lactamase producing Enterobacterales, contributing to poor outcomes • Hospitals and public health authorities should be vigilant for extensively drug resistant bacterial co-infections in patients hospitalized with COVID-19

In this human subject study about interaction with head-up displays (HUDs), the impacts of three types of HUDs (flag, perspective, and flag and perspective) on experienced and inexperienced drivers were subjectively and objectively measured. The driving experiment divided 60 participants into two groups (experienced and inexperienced) and assessed their driving experiences in real high- and low-level driving tasks using the three types of HUDs. During the subjective performance evaluation, the participants executed secondary display tasks and performed a primary driving task with eye-tracking and physiological monitoring. The flag and perspective display (display FP) and the perspective display (display P) were more effective in helping drivers execute simple tasks and complex tasks, and both experienced and inexperienced drivers were HUD-dependent. Based on the study, we provided an optimized design strategy for the HUD interface. Also, we suggest the HUD design should give special consideration for inexperienced drivers.

This research explores some factors affecting purchase and repurchase intentions towards online auctions. An experiment, in the context of PChome & eBay and Yahoo Auction online auctions websites, was conducted to simulate an environment manipulating branding, seller evaluation, volume of information, and price ranges to influence purchase intentions, reflecting some aspects of utilitarian and hedonic approaches towards purchase and repurchase intentions. Furthermore, mediation strategies, trust, and media richness were also introduced in the study to examine their influence on repurchase intentions. 120 participants validated the experimental design, where all variables influencing purchase intentions were found to be significant in varying degrees, and where mediator strategies and trust were found to significantly influence repurchase intentions. These results reinforce notions that online auctions are complex processes, especially to induce purchase and repurchase intentions, and that both buyers and sellers have complex utilitarian and hedonic approaches to develop purchase and repurchase intentions. Further theoretical and managerial implications are detailed in this research. This research examines the factors influencing purchase and repurchase intentions.The study describes some of the complexities and uncertainties in online auctions.Pchome & eBay and Yahoo online auction websites were the basis for the experiment.Product, price, and seller information represented website-based factors.Mediation strategies, media richness, and trust represented seller behavior factors.

ContextThe information technology (IT) field presents a unique context for the management of multiple projects because of the variety of stakeholders involved, the complexity of interdependencies among projects, and the frequent use of external vendors. In practice, IT vendors typically employ advanced project governance techniques such as program management to work effectively with the numbers and variety of clients while still pursuing the benefits of a single oversight. These structural features lend themselves to conflict across teams with individual requirements. However, little research exists on program management, much less in the IT context, that represents conflict across IT project teams. ObjectiveIn this study, the effectiveness of conflict resolution on the implementation efficiency and fulfillment of business objectives is studied through the lens of constructive controversy theories. A number of hypotheses are derived by tailoring the constructive conflict resolution concepts to IT context and making a comprehensive literature review to identify the mediator and dependent variables. A model is developed to consider the management of conflict across multiple projects combined into a single program. MethodA quantitative questionnaire related to the program environment was developed for five variables to include conflict resolution, cognition-based trust, interpersonal cooperation, business objectives and implementation efficiency. The hypotheses were tested by performing a survey study, where a number of well-established measures in the literature were used. 92 paired responses from program teams in 38 organizations located in India were obtained and represent a variety of individual characteristics, and program sizes. ResultsThis study identified the composite role of constructive conflict resolution and cognition-based trust in improving interpersonal cooperation. The impacts of constructive conflict resolution on business objectives were not fully mediated by cognition-based trust and interpersonal cooperation, although implementation efficiency is fully mediated. ConclusionThe management of conflict promotes trust and interpersonal cooperation necessary to improve the efficient completion of the program and benefits to the organization.

© 2014 Elsevier Ltd. This study uses high-frequency appliance-level electricity consumption data for 124 apartments over 24 months to provide a better understanding of appliance-level electricity consumption behavior. We conduct our analysis in a standardized set of apartments with similar appliances, which allows us to identify behavioral differences in electricity use. The Results show that households' estimations of appliance-level consumption are inaccurate and that they overestimate lighting use by 75% and underestimate plug-load use by 29%. We find that similar households using the same major appliances exhibit substantial variation in appliance-level electricity consumption. For example, households in the 75th percentile of HVAC usage use over four times as much electricity as a user in the 25th percentile. Additionally, we show that behavior accounts for 25-58% of this variation. Lastly, we find that replacing the existing refrigerator with a more energy-efficient model leads to overall energy savings of approximately 11%. This is equivalent to results from behavioral interventions targeting all appliances but might not be as cost effective. Our findings have important implications for behavior-based energy conservation policies.

The study proposes a model showing how trust influences the IS Success Model.The proposed model was applied in the context of e-government.The proposed model was used to examine the Philippine online tax system.Trust is a significant influence towards IS Success.Information quality is most influential among the quality dimensions. This study examines citizens' propensity to use e-governmental website services through the lens of the IS Success Model in general, and in the context of the Philippine online tax filing system. Additionally, attributes such as trust in technology, trust in government, trust in e-government websites, and prior experience with government services which act as important antecedents to the model are analyzed in this study. The results show that trust in technology, trust in government, and prior experience directly affected the trust in e-government websites, which in turn directly influenced all three IS quality dimensions. Of these three dimensions, information quality was found to be the most consistently and significantly influence perceptions of usefulness and satisfaction, implying that this dimension is the most critical one beyond the service quality and system quality for taxpayers to use the system. Generally speaking, Philippine taxpayers do value the online system, indicating the fact that the current system does have some potential to elicit favorable perceptions on usefulness, satisfaction, and subsequent net benefits. Other theoretical and managerial implications are further discussed.

The viability of networked communities depends on the creation and disclosure of user-generated content and the frequency of user visitation (Facebook 10-K Annual Report, 2012). However, little is known about how to align the interests of user and social networking sites. In this study, we draw upon the principal-agent perspective to extend Pavlou et al.'s uncertainty mitigation model of online exchange relationships (2007) and propose an empirically tested model for aligning the incentives of the principal (user) and the agent (service provider). As suggested by Pavlou et al., we incorporated a multi-dimensional measure of trust: trust of provider and trust of members. The proposed model is empirically tested with survey data from 305 adults aged 20-55. The results support our model, delineating how real individuals with bounded rationality actually make decision about information disclosure under uncertainty in the social networking site context. There is show little to no relationship between online privacy concerns and information disclosure on online social network sites. Perceived benefits provide the linkage between the incentives of principal (user) and agent (provider) while usage intensity demonstrated the most significant impact on information disclosure. We argue that the phenomenon may be explained through Communication Privacy Management Theory. The present study enhances our understanding of agency theory and human judgment theory in the context of social media. Practical implications for understanding and facilitating online social exchange relationships are also discussed.

a b s t r a c t Engage is a rapidly deployable, retrofit energy monitoring system developed for direct support of a novel energy use behavior investigation and a large-scale deployment in campus apartments. We describe the end-to-end system and report results related to web dashboard engagement during a year-long experi- ment. The objective was to determine user engagement with real-time and easily accessible information about personal energy consumption. Leveraging low-cost components, this system was designed to mea- sure separately appliance plug load, heating and cooling, and lighting electrical load in dense-occupancy building environments. We developed and used an open source technology for measurement of plug load and developed signal processing algorithms to significantly improve measurement accuracy. We also developed proxy sensors to measure heating and cooling and lighting. Our results indicate that 90% of the dashboard activity was undertaken by 50% of the participants and that website engagement was more likely in mid-day and more effective in combination with email reminders. Energy conservation was achieved when combining the dashboard with public information about energy consumption. Published by Elsevier B.V.

Bilingual college students in Ecuador were presented with a Spanish-language website (either a video website or an online newspaper website). Each website contained a banner ad. The ad was for either a high-involvement product (a smartphone) or a low-involvement product (a news magazine). The type of ad (display ad with photograph vs. text-only, Google-style search ad), shape of ad (horizontal vs. vertical ad), and language of the ad (English vs. Spanish) varied for each type of website. The high-involvement product was seen as significantly more appealing than the low-involvement product, regardless of the type of ad. An interaction suggested that the high-involvement product was seen as somewhat more appealing if advertised with display ads rather than text-only ads; the low-involvement product was slightly more appealing if advertised with text-only ads. Both products - but especially the high-involvement product - attracted higher ratings if advertised with Spanish-language ads rather than English ads. Finally, products were somewhat more appealing if advertised on 'highly congruent' websites, where the advertised product was similar to the theme of the website (e.g., a smartphone that plays videos advertised on a video website; a news magazine advertised on a newspaper website).

This exploratory paper reports how Singapore youths participate in new media. Drawing from Ito's concept of genres of online participation which showed that youth participation in new media in the United States is largely friendship-driven and/or interest- driven, this qualitative research aims to find out to what extent Singapore youths are engaged in new media to socialize (friendship-driven) and/or pursue self-directed learning (interest-driven). Our study revealed that school has a central influence on their new media engagement. The emphasis on school reflects the influence of Singapore's high-stakes examinations on youth's engagement in new media.

This study incorporated attitude toward a site (Ast) in the proposed model together with moderating factors like cultural effects and attitude toward online shopping (Ashop). The proposed model and hypotheses were partially supported in Taiwan's and Thailand's data. Information quality affected both user satisfaction and attitude toward the web site and was the dimension common across both countries. Ashop moderated the effects of system quality on user satisfaction in Taiwan, but moderated information quality in the Thailand. National identity moderated the effect of system quality on both user satisfaction and attitude toward the site in the Thai data.

This research proposes a new active queue management method (or FPID) to improve network congestion, which integrates the random early detection (RED) method and fuzzy proportional integral derivative (FuzzyPID) approach. Fuzzy theory applied together with PID helps control the buffer queue within the target. This article provides the literature and theoretical background of network congestion problems, active queue management methods, automatic control systems, and fuzzy controllers. Following the discussion of the proposed FPID method and the experimental design, a simulation test is conducted and analyzed in comparison to the existing popular active queue management methods. The results prove the superiority of the proposed method.

Despite all the research investigating the impact of data and information technology (IT) breaches to the market value of the breached firms, few studies explore the effects of breach events on the stock price of consulting firms that supplies the know-how and infrastructure to create, implement and maintain those information systems that were hacked. Information transfer theory and capital market expectation suggest that as more data breaches occur every year, investors, clients and customers may well look beyond the faults of the individual firms, and place some responsibility on the shoulders of these IT providers. In this study, we investigated a total of 83 breach events affecting a wide range of US firms in various industries in year 2006 and 2007. We found that the market value of the IT consulting firms is positively associated with the disclosure of IT security breaches. The IT consulting firms realized an average abnormal return of 4.01% during the 2-day period after the announcement. Using the event-study method and Ordinary Least Squares Regression to calculate and analyze these firms' abnormal returns, we found evidence that as the number of breached records increased, the IT consulting firms tended to suffer negative returns. In addition, the observed impact was more salient for breaches that affect technology intensive firms than retailing or other firms. In other words, generally speaking, the IT consulting firms have similar experiences with the attacked firms.

Web technology is changing rapidly every day and the internet has become a lifestyle for people all over the world. The power of the web has changed the way people communicate and do business. With the advance of the internet era, a successful website becomes a critical factor for the success of most businesses. Website design is not only about the look of the website. There are many other factors to consider. A well-designed site can induce users to engage in the website, help them find what they are looking for, and understand where exactly they are on the website. This study investigates the user's perception disorientation, engagement, and intent to use a website in the future by manipulating these three basic factors into eight different experimental conditions. With 2x2x2 experimental design with content familiarity, site breadth, and media richness in website systems, this study suggests that both the main effects and the interaction effects of the experiment factors are significant. This implies that one or more factors can compensate for the weakness of other factors. Furthermore different people have preferences for different factors; therefore website design should not solely focus on a single factor, but should address all of these factors in accordance with the objective of the business.

The characteristics of hydrogen detection using epitaxial graphene covered with platinum are reported. The multi-layered graphene was grown by chemical vapor deposition (CVD) on a Si-polar 4H-SiC substrate. Surface morphology was characterized by scanning electron and atomic force microscopy. Current–voltage measurements and real-time monitoring of the current flow through the graphene/platinum device were used to confirm the response to hydrogen gas. The background temperature was varied from room temperature to 175 °C in order to measure the activation energy of hydrogen detection.

This study focuses on smart phone acceptance in a major delivery service company in Taiwan. Technology Acceptance Model (TAM) was tested in two different forms, the original and with self-efficacy added. A two-dimensional improvement to the theory of self-efficacy was investigated in this research. Only assisted self-efficacy was related to both perceived ease of use and perceived usefulness, but Individual Self-efficacy was only a predictor of perceived ease of use. This result offers new evidence to the debate of the role of self-efficacy on TAM constructs. Interesting findings including a strong influence of perceived ease of use on perceived usefulness and behavioral intention were compared to prior studies to add additional insights for future research.

Technology adoption has been the topic of several theories. We empirically assessed and integrated four models to help in predicting smart phone adoption. The varying factors were combined and a survey was conducted in five sales branches of a delivery service company. Results of the analysis of the collected data show that the relationships amongst constructs were similar. Self-efficacy was a strong predictor of behavioral intention through attitude; after innovation, diffusion theory was added. Attitude towards smart phone adoption was found to be affected mainly by testability and organizational and environmental factors. We decided that an iterative approach to implementing smart phone adoption was effective. Managerial implications are discussed.

For a business school, the selection of its peer schools is an important component of its International Association for Management Education (AACSB) (re)accreditation process. A school typically compares itself with other institutions having similar structural and identity-based attributes. The identification of peer schools is critical and can have a significant impact on a business school's accreditation efforts. For many schools the selection of comparable peer schools is a judgmental process. This study offers an alternative means for selection; a quantitative technique called Kohonen's Self-Organizing Map (SOM) network for clustering. In this research, we first demonstrate the capability of SOM as a clustering tool to visually uncover the relationships among AACSB-accredited schools. The results suggest that SOM is an effective and robust clustering method. Then, we compare the results of SOM with that of other clustering methods, such as K-means, Factor/K-means analysis, and kth nearest neighbor procedure. The objective of this study is to demonstrate that a two-dimensional SOM map can be used to integrate the results of various clustering methods and, thus, act as a visual decision support tool.

We have recently shown that low-flow (10%) ischemia in the isolated piglet heart causes an abrupt fall in mechanical function and metabolic activity (acute hibernation), with nearly complete preservation of high-energy phosphates and glycogen after 2 hours of ischemia. We attempted to determine if norepinephrine, as occurs in vivo, would modify the hibernation process. Piglet hearts were perfused at 37 degrees C with red blood cell-enhanced Krebs-Henseleit solution. Performance of the left ventricle was assessed isovolumetrically. With control coronary flow, norepinephrine (40 ng/ml) caused a approximately 50% increase in pressure-rate product and the rate of change of pressure. When coronary flow was reduced to 10%, these measures fell to levels identical to those of ischemic hearts not exposed to norepinephrine. Changes in myocardial O2 metabolism paralleled mechanical function. Lactate release was quantitatively similar in both groups. However, myocardial adenosine triphosphate was reduced from 29 +/- 1 to 13 +/- 2 mumol/gm and glycogen from 300 +/- 46 to 77 +/- 15 mumol/gm by the presence of norepinephrine. Left ventricular compliance was reduced to 51 +/- 5%, compared with 87 +/- 8% in the group without norepinephrine (p less than 0.001). In the norepinephrine group, correlation between left ventricular stiffness and adenosine triphosphate was poor (r = -0.32). Thus hibernating myocardium does not manifest progressive deterioration in the presence of high concentrations of norepinephrine. Diastolic function is less well preserved, however.

The effects of reduced dietary fat intake on plasma lipid levels were examined in diabetic rats. One week after induction of diabetes (D) with streptozotocin (65 mg/kg, iv), the animals were fed food pellets consisting of 1.5% (D1.5), 2.5% (D2.5) or 5% (D5) fat for two weeks. Irrespective of the diets, both food and water consumed by untreated diabetic rats were 2- to 5-fold greater respectively compared to normal. Plasma glucose concentrations were also similarly increased. Plasma and skeletal muscle lipid levels were significantly greater than controls in D2.5 and D5, but not in the D1.5 group. Plasma and muscle lipid concentrations correlated directly with fat consumption. In D5 rats receiving insulin treatment, plasma glucose and lipid concentrations were comparable to control values. These findings indicate that the degree of hyperlipidemia in chronically diabetic rats is directly related to dietary fat intake. They also demonstrate that dietary interventions can modulate some of the metabolic abnormalities in diabetes.

Selected biochemical parameters of the ventricular myocardium were compared among several orders of adult mammals with established differences in resting heart rate (cattle, 51 beats/min; swine, 68; canine, 107; rabbit, 256; guinea-pig, 273; rat, 355; mouse, 475). It was hypothesized that the biochemical character of mammalian myocardia is associated with the chronic functional demand on the muscle. Therefore, differences observed in the myocardial biochemical potential among the species could reflect differences in resting heart rate. Myocardia from smaller mammals with higher resting heart rate had significantly (P less than 0.05) higher maximal activities of citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, lactate dehydrogenase (muscle/total), hexokinase and oxidation rates of glucose and palmitate than did larger mammals with lower resting heart rate. Maximal activities of phosphorylase and phosphofructokinase were more uniform across the animals. Correlation coefficients determined among average values of measured biochemical parameters and resting heart rate indicated that resting heart rate was closely associated with: citrate synthase (r = 0.86), 3-hydroxyacyl-CoA dehydrogenase (r = 0.93), ratio muscle/total lactate dehydrogenase (r = 0.89), hexokinase (r = 0.89), glucose oxidation (r = 0.88), and palmitate oxidation (r = 0.93). Significant correlations were observed among all of these parameters with the exception of citrate synthase vs. 3-hydroxyacyl-CoA dehydrogenase, and glucose oxidation vs. muscle/total lactate dehydrogenase. It was concluded that the oxidative capacity of mammalian myocardia was closely associated with resting heart rate, whereas the glycolytic potential of the myocardia was more uniform among the species.

The study examined the effect of insulin on glucose metabolism in freshly isolated calcium-tolerant heart myocytes from adult rats. The uptake of 2-deoxyglucose demonstrated an initial lag in response to insulin and the maximal insulin effect was not attained until after 3 min preincubation with the hormone. A dose-response study of 14CO2 production from [14C]glucose revealed that the maximum insulin stimulation of glucose utilization occurred with 5 mU/ml. Both the uptake and the oxidation of glucose proceeded at a linear rate in the absence and presence of insulin. However, insulin exerted a greater effect on the uptake (42-54%) than on the oxidation (17-22%) of exogenous glucose. Incorporation of glucose into glycogen was markedly increased by insulin and resulted in the myocyte glycogen concentration returning to in vivo levels. In the absence of insulin, glucose incorporation plateaued within 10 min of incubation and the glycogen concentration was not altered. Our findings also indicate that at equilibrium, insulin-treated cells exhibited a higher glycogen turnover rate. It thus appears that insulin exerts a differential effect on the different pathways in glucose metabolism in the isolated cardiac cells. This may be related in part to their quiescent state and lower energy demand.

Catecholamines (CAT) given in large doses produce cardiomyopathic changes in several animal species. This study was designed to determine if endogenous release can also induce cardiac injury. Rabbits were infused with doses of tyramine (TYR), ranging from 200 to 500 micrograms/min/kg, i.v. for 90 min. Arterial pressure and heart rate were measured, as were total CAT concentrations, blood gases, pH and glucose. Two days later the animals were killed and cardiac injury assessed using a histological scoring system. All data were compared with controls given saline. Initial CAT averaged 452 pg/ml, rose to 2890 pg/ml after starting TYR, 500 micrograms/min/kg, and remained elevated for the duration of infusion. Circulating CAT levels were a function of TYR dose, and bore a linear relationship to the histological score (P less than 0.001). Development of lesions was unaltered by beta 1 blockade with practolol, but sharply reduced by alpha blockade with phentolamine (P less than 0.01). Pretreatment with insulin also reduced lesion formation, but diabetic (alloxan) rabbits showed no greater CAT injury. It is concluded that endogenous release of CAT induces myocardial injury in the rabbit in a dose-dependent manner. This is unrelated to myocardial O2 demand, and microvascular pathology was absent. Activation of alpha adrenergic pathways is likely the dominant or exclusive mechanism.