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At least 19 recordsLinked to original sources
PubMed1998

Vascular endothelial cell-cardiac myocyte crosstalk in achieving a balance between energy supply and energy use.

In isolated perfused hearts, endothelial cells in the coronary arterial vascular system release substances that can alter the contractility of the cardiac myocytes. There are at least two different substances, one that increases and another that decreases the contractility of cardiac myocytes. The rate of release of these endothelial-derived cardioactive substances depends on the oxygen tension in the immediate vicinity of the cardiac myocytes. As the local oxygen tension increases the contractility changes in the same direction. The oxygen sensor in this regulatory system is the cardiac myocyte, which then releases substances that regulate the secretion of endothelin and a relaxant by endothelial cells. The result is a loop involving cross talk between coronary endothelial cells and cardiac myocytes to modulate cardiac contractility in accordance with the oxygen supply to the cardiac myocytes. Preliminary data suggest that the change in contractility is related to a change in structure and position of the cross bridge due to phosphorylation of a protein in the thick filament.

Animals↗
PubMed1981

[Effect of a 2-day increased energy supply on heat production and energy utilization in full-grown sows].

In a respiration trial with 12 nongravid, nonlactating sows, the effect of supplying energy at greatly discrepant levels for 2 days (18, 45, 4.5 and 4.5 g feed/kg 0.75 per meal) on parameters of energy metabolism was studied in comparison with a consistent feed intake (18 g feed/kg 0.75 per meal). The trial was conducted as a change-over design (AB - BA) and included a total of 24 balance periods. The isoenergetic nutrition was aimed at the maintenance energy level. Digestion coefficients for dry matter, nitrogen, carbon and energy were not affected by the inconsistent distribution of the feed supply. Similarly, all parameters of energy metabolism in the sum of the 2-day periods were not different between the two treatments. The maintenance energy exchange averaged 49.1 MJ/2 . days when the energy supply was inconsistent and 48.4 MJ/2 . days in the control group. In the course of the 48-hour measurements, heat production during inconsistent energy supply was higher by 1.8 MJ on the 1st day and 1.2 MJ lower on the 2nd day than in the control group. The additional energy of 17 MJ (75%) supplied in treatment B on the 1st day above that in the control did not seem to have been stored by fat synthesis within this time.

Animals↗
PubMed1984

Limiting Factors in Photosynthesis: V. Photochemical Energy Supply Colimits Photosynthesis at Low Values of Intercellular CO(2) Concentration.

Although there is now some agreement with the view that the supply of photochemical energy may influence photosynthetic rate (P) at high CO(2) pressures, it is less clear whether this limitation extends to P at low CO(2). This was investigated by measuring P per area as a function of the intercellular CO(2) concentration (C(i)) at different levels of photochemical energy supply. Changes in the latter were obtained experimentally by varying the level of irradiance to normal (Fe-sufficient) leaves of Beta vulgaris L. cv F58-554H1, and by varying photosynthetic electron transport capacity using leaves from Fe-deficient and Fe-sufficient plants. P and C(i) were determined for attached sugar beet leaves using open flow gas exchange. The results suggest that P/area was colimited by the supply of photochemical energy at very low as well as high values of C(i). Using the procedure developed by Perchorowicz et al. (Plant Physiol 1982 69:1165-1168), we investigated the effect of irradiance on ribulose bisphosphate carboxylase (RuBPCase) activation. The ratio of initial extractable activity to total inducible RuBPCase activity increased from 0.25 to 0.90 as leaf irradiance increased from 100 to 1500 microeinsteins photosynthetically active radiation per square meter per second. These data suggest that colimitation by photochemical energy supply at low C(i) may be mediated via effects on RuBPCase activation.

Journal Article↗
PubMed2004

Trends in obesity and energy supply in the WHO MONICA Project.

OBJECTIVE: To examine the relationship between secular trends in energy supply and body mass index (BMI) among several countries. DESIGN: Aggregate level analyses of annually reported country food data against anthropometric data collected in independent cross-sectional samples from 34 populations in 21 countries from the early 1980s to the mid-1990s. SUBJECTS: Population randomly selected participants aged 35-64 y. MEASUREMENTS: BMI data were obtained from the WHO MONICA Project. Food energy supply data were derived from the Food Balance Sheet of the Food and Agriculture Organization of the United Nations. RESULTS: Mean BMI as well as the prevalence of overweight (BMI > or =25 kg/m2) increased in virtually all Western European countries, Australia, the USA, and China. Decreasing trends in BMI were seen in Central and Eastern European countries. Increasing trends in total energy supply per capita were found in most high-income countries and China while decreasing trends existed in Eastern European countries. Between country differences in temporal trends of total energy supply per capita explained 41% of the variation of trends in mean BMI; the effect was similar upon the prevalence of overweight and obesity. Trends in percent of energy supply from total fat per capita had a slight effect on the trends in mean BMI (+7% increment in R2) when the total energy supply per capita was adjusted for, while energy supply from total sweeteners per capita had no additional effect. CONCLUSION: Increasing energy supply is closely associated with the increase of overweight and obesity in western countries. This emphasizes the importance of dietary issues when coping with the obesity epidemic.

Adult↗
PubMed1998

Energy supply and muscle fatigue in humans.

Limitations in energy supply is a classical hypothesis of muscle fatigue. The present paper reviews the evidence available from human studies that energy deficiency is an important factor in fatigue. The maximal rate of energy expenditure determined in skinned fibres is close to the rate of adenosine triphosphate (ATP) utilisation observed in vivo and data suggest that performance during short bursts of exercise (<5 s duration) primarily is limited by other factors than energy supply (e.g. Vmax of myosine adenosine triphosphatase (ATPase), motor unit recruitment, engaged muscle mass). Within 10 s of exercise maximal power output decreases considerably and coincides with depletion of phosphocreatine. During recovery, maximal force and power output is restored with a similar time course as the resynthesis of phosphocreatine. Increases in muscle store of phosphocreatine through dietary supplementation with creatine increases performance during high-intensity exercise. These findings support the hypothesis that energy supply limits performance during high-intensity exercise. It is well documented that pre-exercise muscle glycogen content is related to performance during moderate intensity exercise. Recent data indicates that the interfibre variation in phosphocreatine is large after prolonged exercise to fatigue and that some fibres are depleted to the same extent as after high-intensity exercise. Despite relatively small decreases in ATP, the products of ATP hydrolysis (Pi and free ADP) may increase considerably. Free ADP calculated from the creatine kinase reaction increases 10-fold both after high-intensity exercise and after prolonged exercise to fatigue. It is suggested that local increases in ADP may reach inhibitory levels for the contraction process.

Energy Metabolism↗
PubMed2003

A study on an energy supply method for a transcutaneous energy transmission system.

This study proposes a new type of a transcutaneous energy transmission system (TETS) that can supply electrical power for an implanted device without an external battery. In this system, the power is supplied from the floor to the shoes of the patients through coils that are set beneath the floor and the bottom of the shoes. If the patients wear the special shoes, they will be able to move freely on the specially designed floor without an external battery. Direct current (DC)-DC power efficiency was measured in the experiments, and the results showed that it varies with relative positions between the shoe and the floor coils. The results suggested that three-layered floor coils would enable the system to meet the demand for providing the required power anywhere on the floor without intermission. DC-DC power efficiency could be kept over 60% under the practical condition. It can then be concluded that the proposed system has a potential to provide better quality of life for the patients using a TETS.

Electromagnetic Fields↗
PubMed1995

Dynamics of anaerobic and aerobic energy supplies during sustained high intensity exercise on cycle ergometer.

Eight male subjects were examined for the transition from anaerobic to aerobic energy supplies during supramaximal pedalling for 120 s on a cycle ergometer. The O2 debt and O2 deficit were measured for anaerobic supply, while O2 intake during exercise was measured for aerobic supply. The lactic acid system was also observed through postexercise peak blood lactate concentration [la-]b,peak. Since a continuous observation of O2 debt and [la-]b,peak during a single period of pedalling is not possible, pedalling of seven varying durations (5, 15, 30, 45, 60, 90 and 120 s) were repeated. Mechanical power output reached its peak immediately after the beginning of exercise, then rapidly declined, becoming gradual after 60 s. The O2 debt and O2 deficit were highest immediately after the beginning of exercise, then rapidly decreased to nil in 60 s. The O2 intake was small at the beginning, then rapidly increased to attain a steady state in 30 s at 80%-90% of the maximal O2 intake of the subject. Energy supply from the lactic acid system indicated by the increment in [la-]b,peak reached its highest value during the period between 5 and 15 s, then rapidly decreased to nil in 60 s. The results would suggest that anaerobic supply was the principal contributor during the initial stage of exercise, but that aerobic supply gradually took over. In 60 s anaerobic supply ceased, and aerobic supply became the principal contributor. The cessation of anaerobic energy supply took place much sooner than the 2 min that is conventionally suggested.

Adult↗
PubMed1977

[Selective local hyperthermy of tumor tissue. Homogenized energy supply also to deep-seated tissues by high-performance decametric wave coil section plus dual system raster motion (author's transl)].

Based on results of selective tumor tissue hyperacidification and whole-body hyperthermy the paper deals with the advantages of local hyperthermy and gives a review of the various methods of energy supply for hyperthermy in living tissue. It follows a presentation of physical and biophysical fundamentals on selective local hyperthermy of tumor tissue by radiation, by r. f. rotational magnetic fields and by r. f. capacitor fields. Using a gelatine phantom for measuring the energy supply with the various modes of local hyperthermy it is then shown that it is solely the divergent rotational magnetic field which allows to substantially reduce the inhomogeneity of energy supply also in z-direction (increasing depth in body tissue) by introducing a relative raster motion of the applicator in x-y-direction (plane parallel to body surface). It is only the introduction of the x-y raster principle combined with a described dual system array (CMT Selectotherm System) which permits the high and rather homogeneous supply of thermal energy also to deep-seated tumor tissue in the patient without concomitant critical superheating of tissues near the skin. Finally the paper gives a theoretical derivation of the temperature profile for selective local hyperthermy of tumor tissue. With due consideration of heat dissipation by convection and conduction, this endeavour shows rather promising aspects for the therapeutic efficiency obtainable in each case of treatment.

Animals↗
PubMed2002

Characterization of the cell death modes and the associated changes in cellular energy supply in response to AlPcS4-PDT.

Photodynamic therapy (PDT) can result in both types of cell death, apoptosis or necrosis. Several steps in the induction and execution of apoptosis depend on ATP and the intracellular ATP level has been shown to be one determinant in whether apoptosis or necrosis occurs. Therefore, photochemical damage of cellular targets involved in energy supply might play a crucial role in the mode of cell death being executed. The present study is aimed at the characterization of changes in cellular energy supply and the associated cell death modes in response to PDT. Using the human epidermoid carcinoma cell line A431 and aluminium(III) phthalocyanine tetrasulfonate chloride (2.5 microM) as a photosensitizer, we studied the changes in mitochondrial function and intracellular ATP level after irradiation with different light doses. Employing assays for caspase-3 activation and nuclear fragmentation, 50% of the cells were found to undergo apoptosis after irradiation between 2.5 to 3.5 J cm(-2) while the remainder died by necrosis. At higher light doses (> 6 J cm(-2)), neither caspase-3 activation nor nuclear fragmentation was observed and this suggests that these cells died exclusively by necrosis. Necrotic cell death was also associated with a rapid decline in mitochondrial activity and intracellular ATP. By contrast, with apoptosis the loss of mitochondrial function was delayed and the ATP level was maintained at near control levels for up to eight hours which was far beyond the onset of morphological changes. These data suggest that, depending on the light dose applied, both, necrosis as well as apoptosis can be induced with AlPcS4 mediated PDT and that photodamage in energy supplying cellular targets may influence the mode of cell death. Further, it is speculated that cells undergoing apoptosis in response to PDT might maintain a high ATP level long enough to complete the apoptotic program.

Adenosine Triphosphate↗
PubMed1983

Postnatal development of the energy supplying enzyme pattern in the rat brain.

The activity of seven enzymes connected with energy-supplying metabolism was followed from the second day of life till adulthood (87th day). The enzymes selected were: 1. Triosephosphate dehydrogenase (TPDH), 2. Lactate dehydrogenase (LDH), 3. Glycerol-3-phosphate: NAD dehydrogenase (GPDH), 4. Hexokinase (HK), 5. Malate: NAD dehydrogenase (MDH), 6. Citrate syntase (CS) and 7. 3-Hydroxyacyl Co A dehydrogenase. Although some variations occurred, the enzyme profiles were characteristic of those of the nervous tissue from the second day of life onwards until adulthood and displayed relatively high activities of HK, CS and MDH and low activities of TPDH, LDH, GPDH and HOADH. The activities of all enzymes studied here increased during postnatal development and some reached adult values on the 14th day, that of TPDH on the 27th day and HOADH on the 41st day of life. The activities of MDH and GPDH did not attain the adult values still on the 41st day of life. The anaerobic energy supply capacity seems to increase transiently on the 31st day of life, i.e. at a developmental stage where the resistance against hypoxia is known to increase transiently.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed2001

Regional industrial ecology: examples from regional economic systems of forest industry and energy supply in Finland.

Industrial ecology (IE) promotes the development of industrial systems based on recycling of matter and cascading of energy through cooperation. In this paper, the local/regional industrial ecosystem approach is reflected in two examples from Finland. The local forest industry system is based on renewable resources, waste materials and energy utilisation between forestry companies, a saw-mill, a pulp mill, a paper mill and a forest industry power plant. Waste energy from electricity production is used for production of heat and process steam. Regional city energy supply systems in Finland are also to a large extent arranged around power plants that utilise waste energy. The potential of combining the forest industry system with the energy supply systems of cities is considered and the conditions for success in the Finnish case are discussed.

Cities↗
PubMed1993

Effect of body condition and dietary energy supply on reproductive processes in the female mink (Mustela vison).

This paper reviews a series of experiments regarding the influence of body condition and dietary energy supply on reproductive processes in the female mink. The reporting is based on 1905 sets of reproductive performance data and on data regarding number of corpora lutea, implantation rate, plasma progesterone and oestradiol, luteinizing hormone (LH) release and ovulation rate, and the early development of the fertilized ova. Generally, treatment effects were more pronounced in yearling females than in adults; furthermore, adults responded less to varied energy supply by changes in body weight. A weight reduction of > 300 g during the winter resulted in poor reproductive performance in yearling females. A long-term study indicated better reproductive longevity for females on a low-intensity feeding regimen, whereas females on a high-intensity feeding regimen tended to have larger litters until 3 years of age. Nutritional flushing was carried out by a 2-week period of moderate energy restriction followed by feeding ad libitum from 3-5 days before initiation of matings until matings were completed for the individual females. Mainly in yearlings, but also in adults, litter sizes were improved for females with a first mating early in the breeding season, which was confirmed by an increased number of corpora lutea. The interval between the first recorded increase in plasma progesterone and the day of the peak progesterone concentration was decreased. Plasma oestradiol concentrations were higher in flush-fed females; age-dependent differences in the appearance of the profiles were also found. LH release tended to be more synchronized and distinct in flush-fed females.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed2001

Ontogenetic development of energy-supplying enzymes in rat and guinea-pig heart.

The purpose of the present study was to compare the ontogenetic development of the activity of myocardial energy-supplying enzymes in two mammalian species, differing significantly in their level of maturation at birth. The animals were investigated during the late prenatal period and 2, 7, 14, 21, 25, 30, 63, 120 and 730 days after birth in the rat and 2, 21, 84 and 175 days in the guinea-pig. The following enzymes were assayed in the right and left ventricular myocardium: lactate dehydrogenase (LDH, lactate uptake and/or formation), triose phosphate dehydrogenase (TPDH, carbohydrate metabolism), glycerol phosphate dehydrogenase (GPDH, glycerol-P shuttle)), hexokinase (HK, glucose phosphorylation), malate dehydrogenase (MDH, tricarboxylic cycle), citrate synthase (CS, tricarboxylic cycle) and hydroxyacyl-CoA dehydrogenase (HOADH, fatty acid breakdown). The rat heart, highly immature at birth, exhibits three different developmental patterns of energy-supplying enzymes, identical in both ventricles: (i) two mitochondrial enzymes of aerobic metabolism (CS, HOADH) and GPDH have a relatively low activity at the end of prenatal life; thereafter their activity steadily increases, approaching the adult levels between the 3rd and 4th postnatal weeks. A significant decrease was observed between the 4th and 24th months. (ii) MDH and LDH: prenatal values were significantly higher as compared with the 2nd postnatal day; after this period the activities increased up to adulthood (4 months) and decreased during senescence. (iii) The activities of HK and TPDH are characterized by only moderate changes during development. HK differs from all other enzymes by the highest prenatal values, which exceed even adult values. In contradiction to the rat heart, the developmental differences in more mature guinea-pig heart were significantly less pronounced. The only ontogenetic differences observed were the lower activities of enzymes connected with aerobic metabolism at the end of the prenatal period. Our results point to possible differences in the development of adaptive metabolic pathways in animals with different levels of maturation at birth.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1985

[Adipose tissue cellularity in the piglet as a function of the level of energy supply of the maternal diet and the number of young per litter].

Adipose tissue cellularity has been evaluated in piglets at birth and at weaning at 35 days in relation with the energy supply of the maternal diet during gestation (group B: 3 000 KcalED/day: group N; 6 500 KcalED/day; group H: 10 000 Kcal/day) and with the number of piglets per litter during suckling. This approximation was obtained by simultaneously measuring piglet carcass triglyceride content and the mean diameter of the lipid inclusions of the fat cell population. At birth there were no significant differences between N and H piglets. However, B piglets weighed less and had lower lipid stores than the piglets of the other two groups. This lower adiposity was due to the smaller number of fat cells (about--25%). A weaning piglet weight and adiposity depended on both the energy supply of the maternal diet during gestation and the number of piglets per litter. These differences were due to the number of fat cells; this number was usually greater when the maternal diet during gestation had a higher energy level and the number of piglets per litter was smaller. Between birth and weaning the number of fat cells increased by a factor related with the number of piglets per litter; this factor was 1.9 or 2.5, depending on whether the sow suckled 4 or 8 piglets.

Adipose Tissue↗
PubMed1984

[Mechanisms of disordered cardiac energy supply in transient coronary insufficiency].

Experiments conducted on 240 albino non-inbred male rats, using models of transitory coronary insufficiency of various duration (the period of myocardial ischemia lasted 10, 40 and 120 min), showed impaired energy supply to the heart in both periods of its ischemia and reperfusion in relation to three principal stages; first the synthesis of ATP, then the transportation and utilization of its energy. The period of ischemia was associated with disorders of predominantly the ATP synthesis and to a lesser degree of the transport and utilization of its energy. In the period of the post-infarction resumption of the coronary blood flow mostly affected were the mechanisms of the transportation and absorption of ATP energy by the effector apparatus of cardiomyocytes. At the early stage of myocardial reperfusion after a prolonged (40 and 120 min) local ischemia, the heart was damaged to a greater degree than in continuing ischemia of the same duration. The development of transitory coronary insufficiency following the preliminary administration of the antihypoxant gutimin is characterized by less marked disorders in the process of cardiac energy supply both in the period of myocardial ischemia and at the early stage of the reperfusion.

Adenosine Triphosphate↗
PubMed1982

[Growth studies of fattening hybrid heifers. 3. Studies of the total retention of fattening hybrid heifers under different energy supply].

These investigations show that daily retention in the course of growth is subject to dynamic changes specific for each nutrient. While there are only insignificant differences between daily live weight growth as the practically usable parameter and body weight growth, daily dry matter deposition takes a comparatively different development. The specific development of dry matter deposition depends on the daily retention of protein and fat. Whereas in early age protein retention is higher, fat retention increases in the course of live weight development in dependence on the energy level. Different energy supply results in distinctly differentiated protein, fat and energy retention per day. The highest variation in daily retention could be ascertained for fat retention in dependence on energy supply. A comparison of the cumulated experimental results with model values generalised from the growth function corresponded well.

Animals↗
PubMed2005

[The influence of deficient and excessive dietary energy supply on immune system functioning].

There is direct dependence between immune system functioning and nutritional value of food. Balanced diet satisfies energetic demand of body cells, including immune system cells which constitute nonspecific barrier and a specific defense against infection. Both too low and excessive energy supply in food have negative influence on cell-mediated and humoral immunity of the organism. The article deals with the influence of protein-energy malnutrition on immunity mechanisms mobility and immunity consequences of excessive dietary energy supply concurrent with obesity taking into consideration patient age groups.

Energy Metabolism↗