Effect of epinephrine on glucose disposal during exercise in humans: role of muscle glycogen

This study examined the effect of epinephrine on glucose disposal during moderate exercise when glycogenolytic flux was limited by low preexercise skeletal muscle glycogen availability. Six male subjects cycled for 40 min at 59 ± 1% peak pulmonary O₂ uptake on two occasions, either without (CON) or with (EPI) epinephrine infusion starting after 20 min of exercise. On the day before each experimental trial, subjects completed fatiguing exercise and then maintained a low carbohydrate diet to lower muscle glycogen. Muscle samples were obtained after 20 and 40 min of exercise, and glucose kinetics were measured using [6,6-²H]glucose. Exercise increased plasma epinephrine above resting concentrations in both trials, and plasma epinephrine was higher (P < 0.05) during the final 20 min in EPI compared with CON. Muscle glycogen levels were low after 20 min of exercise (CON, 117 ± 25; EPI, 122 ± 20 mmol/kg dry matter), and net muscle glycogen breakdown and muscle glucose 6-phosphate levels during the subsequent 20 min of exercise were unaffected by epinephrine infusion. Plasma glucose increased with epinephrine infusion (i.e., 20-40 min), and this was due to a decrease in glucose disposal (R_d) (40 min: CON, 33.8 ± 3; EPI, 20.9 ± 4.9 µmol · kg^-1 · min^-1, P < 0.05), because the exercise-induced rise in glucose rate of appearance was similar in the trials. These results show that glucose R_d during exercise is reduced by elevated plasma epinephrine, even when muscle glycogen availability and utilization are low. This suggests that the effect of epinephrine does not appear to be mediated by increased glucose 6-phosphate, secondary to enhanced muscle glycogenolysis, but may be linked to a direct effect of epinephrine on sarcolemmal glucose transport.

Effect of alcohol intake on muscle glycogen storage after prolonged exercise

We studied the effects of alcohol intake on postexercise muscle glycogen restoration with samples from vastus lateralis being collected immediately after glycogen-depleting cycling and after a set recovery period. Six well-trained cyclists undertook a study of 8-h recovery (2 meals), and another nine cyclists undertook a separate 24-h protocol (4 meals). In each study, subjects completed three trials in crossover order: control (C) diet [meals providing carbohydrate (CHO) of 1.75 g/kg]; alcohol-displacement (A) diet (1.5 g/kg alcohol displacing CHO energy from C) and alcohol + CHO (AC) diet (C + 1.5 g/kg alcohol). Alcohol intake reduced postmeal glycemia especially in A trial and 24-h study, although insulin responses were maintained. Alcohol intake increased serum triglycerides, particularly in the 24-h study and AC trial. Glycogen storage was decreased in A diets compared with C at 8 h (24.4 ± 7 vs. 44.6 ± 6 mmol/kg wet wt, means ± SE, P < 0.05) and 24 h (68 ± 5 vs. 82 ± 5 mmol/kg wet wt, P < 0.05). There was a trend to reduced glycogen storage with AC in 8 h (36.2 ± 8 mmol/kg wet wt, P = 0.1) but no difference in 24 h (85 ± 9 mmol/kg wet wt). We conclude that 1) the direct effect of alcohol on postexercise glycogen synthesis is unclear, and 2) the main effect of alcohol intake is indirect, by displacing CHO intake from optimal recovery nutrition practices.

Effect of accurate exercise on uncoupling protein3 is a fat metabolism-mediated effect

Human and rodent uncoupling protein (UCP)3 mRNA is upregulated after acute exercise. Moreover, exercise increases plasma levels of free fatty acid (FFA), which are also known to upregulate UCP3. We investigated whether the upregulation of UCP3 after exercise is an effect of exercise per se or an effect of FFA levels or substrate oxidation. Seven healthy untrained men [age: 22.7 ± 0.6 yr; body mass index: 23.8 ± 1.0 kg/m²; maximal O₂ uptake (VO_{2 max}): 3,852 ± 211 ml/min] exercised at 50% VO_{2 max} for 2 h and then rested for 4 h. Muscle biopsies and blood samples were taken before and immediately after 2 h of exercise and 1 and 4 h in the postexercise period. To modulate plasma FFA levels and fat/glucose oxidation, the experiment was performed two times, one time with glucose ingestion and one time while fasting. UCP3 mRNA and UCP3 protein were determined by RT-competitive PCR and Western blot. In the fasted state, plasma FFA levels significantly increased (P < 0.0001) during exercise (293 ± 25 vs. 1,050 ± 127 μmol/l), whereas they were unchanged after glucose ingestion (335 ± 54 vs. 392 ± 74 µmol/l). Also, fat oxidation was higher after fasting (P < 0.05), whereas glucose oxidation was higher after glucose ingestion (P < 0.05). In the fasted state, UCP3L mRNA expression was increased significantly (P < 0.05) 4 h after exercise (4.6 ± 1.2 vs. 9.6 ± 3.3 amol/µg RNA). This increase in UCP3L mRNA expression was prevented by glucose ingestion. Acute exercise had no effect on UCP3 protein levels. In conclusion, we found that acute exercise had no direct effect on UCP3 mRNA expression. Abolishing the commonly observed increase in plasma FFA levels and/or fatty acid oxidation during and after exercise prevents the upregulation of UCP3 after acute exercise. Therefore, the previously observed increase in UCP3 expression appears to be an effect of prolonged elevation of plasma FFA levels and/or increased fatty acid oxidation.

An empirical investigation of the effect of interaction justice perception on consumer intentions after complaining

This study examined how apology as interaction justice impacts on consumer perceptions of service recovery attempt.  Data was collected using hypothetical scenarios.  Two types of service failures were proposed and the impact of recovery action on each failure type was compared.  Findings include that there is direct effect of recovery action on consumer future intentions in both type of failures.  Implications and direction to the future research were proposed.

Animal–plant–microbe interactions : direct and indirect effects of swan foraging behaviour modulate methane cycling in temperate shallow wetlands

Wetlands are among the most important ecosystems on Earth both in terms of productivity and biodiversity, but also as a source of the greenhouse gas CH₄. Microbial processes catalyzing nutrient recycling and CH₄ production are controlled by sediment physico-chemistry, which is in turn affected by plant activity and the foraging behaviour of herbivores. We performed field and laboratory experiments to evaluate the direct effect of herbivores on soil microbial activity and their indirect effects as the consequence of reduced macrophyte density, using migratory Bewick’s swans (Cygnus columbianus bewickii Yarrell) feeding on fennel pondweed (Potamogeton pectinatus L.) tubers as a model system. A controlled foraging experiment using field enclosures indicated that swan bioturbation decreases CH₄ production, through a decrease in the activity of methanogenic Archaea and an increased rate of CH₄ oxidation in the bioturbated sediment. We also found a positive correlation between tuber density (a surrogate of plant density during the previous growth season) and CH₄ production activity. A laboratory experiment showed that sediment sterilization enhances pondweed growth, probably due to elimination of the negative effects of microbial activity on plant growth. In summary, the bioturbation caused by swan grazing modulates CH₄ cycling by means of both direct and indirect (i.e. plant-mediated) effects with potential consequences for CH₄ emission from wetland systems.

Natural selection for earlier male arrival to breeding grounds through direct and indirect effects in a migratory songbird

For migratory birds, the earlier arrival of males to breeding grounds is often expected to have fitness benefits. However, the selection differential on male arrival time has rarely been decomposed into the direct effect of male arrival and potential indirect effects through female traits. We measured the directional selection differential on male arrival time in the pied flycatcher (Ficedula hypoleuca) using data from 6 years and annual number of fledglings as the fitness proxy. Using structural equation modeling, we were able to take into account the temporal structure of the breeding cycle and the hierarchy between the examined traits. We found directional selection differentials for earlier male arrival date and earlier female laying date, as well as strong selection differential for larger clutch size. These selection differentials were due to direct selection only as indirect selection for these traits was nonsignificant. When decomposing the direct selection for earlier male arrival into direct and indirect effects, we discovered that it was almost exclusively due to the direct effect of male arrival date on fitness and not due to its indirect effects via female traits. In other words, we showed for the first time that there is a direct effect of male arrival date on fitness while accounting for those effects that are mediated by effects of the social partner. Our study thus indicates that natural selection directly favored earlier male arrival in this flycatcher population.

Teachers' work hours, work-family conflict and health: the mediating effects of perceived control and organisational support

Teachers are among those working longer hours more than ever before. the implications of these long hours on teachers' health, through work-family conflict, control over hours worked and organisational support were investigated. 120 teachers, of whom 91 (59.3% female) reported
working in excess of 37 1/2 hours in the week prior, participated in the study. Long hours, work-family conflict, control and organisational support, explained 69% of the variance in health. There was no direct effect of long worked hours on health however long hours did have a direct impact on work-family conflict, organisational support, and control and, through
these, teachers' health. Work-family conflict exerted a direct negative impact on health. These findings are discussed in individual and organisational tenns.

What will affect software reuse: a causal model analysis

Software reuse is an important topic due to its potential benefits in increasing product quality and decreasing cost. Although more and more people are aware that not only technical issues, but also nontechnical issues are important to the success of software reuse, people are still not certain which factors will have direct effect on the success of reuse. In this paper, we applied a causal discovery algorithm to the software reuse survey data [2]. Ensemble strategy is incorporated to locate a probable causal model structure for software reuse, and find all those factors which have direct effect on the success of reuse. Our discovery results reinforced some conclusions of Morisio et al. and found some new conclusions which might significantly improve the odds of a reuse project succeeding.

Nocodazole inhibits insulin-stimulated glusocs transport in 3T3-L1 adipocytes via a microtubule independant mechanism

Insulin stimulates glucose transport in adipocytes and muscle cells by triggering redistribution of the GLUT4 glucose transporter from an intracellular perinuclear location to the cell surface. Recent reports have shown that the microtubule-depolymerizing agent nocodazole inhibits insulin-stimulated glucose transport, implicating an important role for microtubules in this process. In the present study we show that 2 µM nocodazole completely depolymerized microtubules in 3T3-L1 adipocytes, as determined morphologically and biochemically, resulting in dispersal of the perinuclear GLUT4 compartment and the Golgi apparatus. However, 2 µM nocodazole did not significantly effect either the kinetics or magnitude of insulin-stimulated glucose transport. Consistent with previous studies, higher concentrations of nocodazole (10-33 µM) significantly inhibited basal and insulin-stimulated glucose uptake in adipocytes. This effect was not likely the result of microtubule depolymerization because in the presence of taxol, which blocked nocodazole-induced depolymerization of microtubules as well as the dispersal of the perinuclear GLUT4 compartment, the inhibitory effect of 10-33 µM nocodazole on insulin-stimulated glucose uptake prevailed. Despite the decrease in insulin-stimulated glucose transport with 33 µM nocodazole we did not observe inhibition of insulin-stimulated GLUT4 translocation to the cell surface under these conditions. Consistent with a direct effect of nocodazole on glucose transporter function we observed a rapid inhibitory effect of nocodazole on glucose transport activity when added to either 3T3-L1 adipocytes or to Chinese hamster ovary cells at 4 °C. These studies reveal a new and unexpected effect of nocodazole in mammalian cells which appears to occur independently of its microtubule-depolymerizing effects.

A perspective on the role of natriuretic peptides in amphibian osmoregulation

The natriuretic peptide (NP) system is a complex family of peptides and receptors that is primarily linked to the maintenance of osmotic and cardiovascular homeostasis. In amphibians, the potential role(s) of NPs is complicated by the range of osmoregulatory strategies found in amphibians, and the different tissues that participate in osmoregulation. Atrial NP, brain NP, and C-type NP have been isolated or cloned from a number of species, which has enabled physiological studies to be performed with homologous peptides. In addition, three types of NP receptors have been cloned and partially characterised. Natriuretic peptides are always potent vasodilators in amphibian blood vessels, and ANP has been shown to increase the permeability of the microcirculation. In the perfused kidney, ANP causes vasodilation, diuresis and natriuresis that are caused by an increased GFR rather than effects in the renal tubules. These data are supported by the presence of ANP receptors only on the glomeruli and renal blood vessels. In the bladder and skin, the function of NPs is enigmatic because physiological analysis of the effects of ANP on bladder and skin function has yielded conflicting data with no clear role for NPs being revealed. Overall, NPs often have no direct effect, but in some studies they have been shown to inhibit the function of AVT. In addition, there is evidence that ANP can inhibit salt retention in amphibians since it can inhibit the ability of adrenocorticotrophic hormone or angiotensin II to stimulate corticosteroid secretion. It is proposed that an important role for cardiac NPs could be in the control of hypervolaemia during periods of rapid rehydration, which occurs in terrestrial amphibians.

A causal analysis for the expenditure data of business travelers

Determining the causal relation among attributes in a domain
is a key task in the data mining and knowledge discovery. In this
paper, we applied a causal discovery algorithm to the business traveler
expenditure survey data [1]. A general class of causal models is adopted in
this paper to discover the causal relationship among continuous and discrete variables. All those factors which have direct effect on the expense
pattern of travelers could be detected. Our discovery results reinforced
some conclusions of the rough set analysis and found some new conclusions which might significantly improve the understanding of expenditure behaviors of the business traveler.

The mediating role of competitive advantage in the relationship between organisational capabilities and retail performance

This paper investigates the relationships between market, learning and brand orientation with competitive advantage and organisational performance in the context of the UK retail industry. The results indicate that competitive advantage contributes to strategic effectiveness and mediates the relationship between learning and brand orientation and strategic effectiveness. No significant relationship was found in relation to financial performance. Moreover, market orientation was not found to have a significant direct effect on competitive advantage or indirect affect on performance.

Role of organizational service recovery actions on sustomer switching intentions in a process based service failure : does speed of recovery matters?

The study examines how organizational activities of compensation and empowerment impact on consumers switching intentions and also whether these differ based on the speed of service recovery. Data is collected using hypothetical scenarios in a situation of process failure. It is found that there is no direct effect of either compensation or empowerment on switching intent, although the interaction effect is significant when recovery occurs quickly.

The impact of consumer ethnocentrism and country of origin sub-components for high involvement products on young Chinese consumers' product assessments

Purpose – The purpose of this paper is to examine the effect of country of origin (COO) sub-components (i.e. design, assembly and parts), as well as the extent to which consumer ethnocentrism tendencies interact with these COO sub-components for young Chinese consumers with regards to product quality assessments and purchase intentions.

Design/methodology/approach – A 2?×?2?×?2 factorial experimental design was used to examine the effects of the three sub-components of COO with two levels of sourcing location – Home (China) and Foreign (Germany), for two high involvement products (an automobile and a digital camera). Chinese students in China represented the sample of 272 respondents. MANOVA was used to examine the direct effects and interactions of the three COO components, as well as ethnocentrism, measured using the CETSCALE.

Findings – It was found that the three COO sub-components did not influence young Chinese consumers’ evaluation of product quality or purchase intentions. In addition, consumers’ level of ethnocentrism also did not have a direct effect on perceived product quality or purchase intentions. There was only one statistically significant interaction effect between ethnocentrism and country of parts for one of the two products. As such, COO dimensions and young Chinese consumers’ ethnocentrism appears to have limited influence on their assessments of product quality or purchase intentions. This may occur because young Chinese consumers perceive that hybrid products are the norm for high involvement products in China as these products are all these consumers have experienced.

Originality/value – The findings of this research dispute the commonly held belief and evidence that sub-components of COO have an impact on the perceptions of product quality and purchase intentions. Young Chinese consumers may be different to consumers from western countries because they have been extensively exposed to hybrid products. Given the size and growth potential of China, young Chinese are an important, under-researched segment within the Chinese market.

Traffic fatalities: does income inequity create an externality?

Responsible for 20 million severe injuries and/or deaths annually, few epidemics receive less attention than traffic accidents. Going beyond confirming an inverted U-shaped relationship between mean income and fatalities, we show theoretically that income inequality can positively affect fatalities in two ways. Each operates through heterogeneity between road users, and while the direct effect can be expected to evaporate with rising income, the indirect effect may prove to be an externality in that the relationship remains regardless of the level of income. Our model is supported by evidence from 79 countries between 1970 and 2000.