SEARCH · PubMed Health

Results for “Energy”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1977

Variations in the adenylate energy charge during phased growth (cell cycle) of Candida utilis under energy excess and energy-limiting growth conditions.

The variations in the levels of adenine nucleotides during the phased growth (cell cycle) of the yeast Candida utilis growing under nitrogen, sulfate, or iron limitation with glycerol as carbon source have been determined. Synchronous cultures were obtained by the continuous phasing technique, and the results were compared with those of chemostat cultures growing at similar growth rates and under the same types of nutrient limitation. Whereas the chemostat experiments indicated only the average energy status of cultures growing at random, results from phased cultures showed that the adenylate energy charge, defined as (ATP + (1/2)ADP)/(ATP + ADP + AMP) (where ATP, ADP, and AMP signify adenosine 5'-triphosphate, -diphosphate, and -monophosphate, respectively), varied during the phased growth of the yeast. These variations were related to the stage of development of the cells and to the type of nutrient limitation. In every case the energy charge dropped to a low value during the first half of the phasing cycle (cell cycle). Whereas the energy charge was maintained at relatively high levels (ranging from 0.78 to 0.94), for sulfate- or nitrogen-limited cultures, it was very low when iron was the growth-limiting nutrient (0.44 to 0.78). In spite of the low energy charge, the yeast continued to grow under iron limitation. The main component of the adenylate pool of the iron-limited culture was ADP and not ATP as observed with other types of nutrient limitation. It is concluded that under iron limitation the growth of the organism is limited by energy and that under energy-limited growth the energy charge of a growing organism is maintained at low levels. The reason for maintaining a low energy charge in an energy-limited culture is discussed.

Adenine Nucleotides↗

PubMed1977

[Energy and nutrient supply during childhood. I. Food intake and energy supply (author's transl)].

From 1965--1975 the food intake and energy supply of children aged 2--14 years in families of different social classes were studied with the precise weighing method. The individual child was surveyed on an average of 21--42 successive days. Energy intake increased from 1450 for boys aged 2--3 years to 2600 kcal/day for boys aged 12--14 years, girls of the same age had an energy intake between 1300 to 2400 kcal/day. The differences between boys and girls regarding energy intake, absolute and per kg body weight, are shown. Our results of the energy intake are representative for children of the same age groups in other highly industrialized countries. The energy intake of preschool-children was equally distributed among 4 meals per day, whereas in school-children it was distributed among 5 meals with different energy contents. 35--50% of the energy supply is of animal origin, 60--65% of vegetable origin. The contribution of different food groups to the energy supply and the differences in the intake of these food groups between pre-school-and school-children are demonstrated. For the individual child a survey period of 21--28 days is necessary to obtain its individual average energy intake with the maximum standard deviation. The significance of general averages for the energy supply of age groups regarding the individual child is discussed. The day to day variations of energy intake in children are shown. The significance of these variations for nutrition in health and disease is discussed.

Adolescent↗

PubMed1979

Maintenance energy requirements, energy retention and heat production of young obese (ob/ob) and lean mice fed a high-fat or a high-carbohydrate diet.

Female obese (ob/ob) and lean mice were weaned at 21 days of age, placed in wire-mesh cages maintained at 25 to 30 degrees, and fed a high-fat or a high-carbohydrate diet for 21 days. The body energy balance procedure was utilized to determine the maintenance energy requirements, and the efficiency of dietary energy utilization, above maintenance, in these mice. Heat production of each mouse was measured weekly in a gradient-layer calorimeter. Regressions of changes in body energy per kg3/4 on metabolizable energy intake per kg3/4 indicated that the maintenance energy requirement averaged 72 kcal/kg3/4/day for obese mice and 124 kcal/kg3/4/day for lean mice. Diet composition did not influence the maintenance energy requirements, but utilization of energy, above maintenance, in obese mice fed the high-fat diet was 41% more efficient than observed in obese mice fed the high-carbohydrate diet and 38 to 71% more efficient than observed in lean mice. Heat production, per unit body weight was lower in obese mice than in lean mice. The lowest heat production was observed in obese mice fed the high-fat diet. The 40% lower maintenance energy requirement of the obese mice is a major factor contributing to the high efficiency of energy retention in these mice. Consumption of a high-fat diet further improved the ability of the obese mice to retain dietary energy.

Animals↗

PubMed1979

Energy retention, energy expenditure, and growth in healthy immature infants.

Energy balance studies were done during 10-29 days on 15 immature infants of mean birth weight 1581 g. Mean gross energy intake was 757 kJ/kg (181 kcal) and 79% of this was retained, so that metabolizable energy was 602 kJ/kg (143 kcal). Mean resting metabolic rate was 244 kJ/kg (58.1 kcal), and it increased with advancing maturity. Minimum resting metabolism averaged 199 kJ/kg (47.5 kcal). Energy expended in activity increased with maturity, but amounted to less than 17% of the total energy turnover. Postprandial metabolism caused the mean VO2 to rise by 17% in the hour after a feed, and during 24 hr resulted in consumption of energy equivalent to about 10% of the resting metabolism. Stored energy amounted to 230 kJ/kg (55 kcal) and was linearly related to weight gain (r = 0.92). Energy cost of weight gain was 24 kJ/g (5.7 kcal) and energy stored in new tissue was 16.8 kJ/g (4.0 kcal). Maintenance energy requirement at zero growth rate was about 270 kJ/kg (64 kcal).

Energy Metabolism↗

PubMed1977

Comparison between antigen-antibody binding energies and interfacial free energies.

Antigen-antibody binding energies derived from equilibrium data are compared with the binding energies resulting from the interfacial free energies obtained from contact angle measurements of antigens and antibodies. From these interfacial free energies two sorts of theoretical antigen-antibody binding energies can be derived, as well as the Hamaker constants for most antigen-antibody systems. For interaction in vacuo the Hamaker constants obtained are between 4 and 6 X 10(-13) ergs, while these constants for hydrated antigen antibody interactions are less than 10(-14) ergs. For interactions in vacuo, interfacial free energies yield binding energies (delta Fa) that lie between -120 and -140 ergs/cm2. For interactions in the aqueous phase (with interstitial water still present), much lower binding energies (delta Fb) are derived, of the order of -.01 and -1 ergs/cm2. In comparison, dextran-anti-dextran interactions show a binding energy derived from equilibrium data (delta Feq) of the order of -10 ergs/cm2. In general the equilibrium binding energies delta Feq of most antigen-antibody systems would vary between -1 and -20 ergs/cm2. The implications of this comparison are discussed in the light of the influence of residual water between antigenic determinant and antibody-active site, as well as in the light of the degree of perfection of fit between these sites.

Antibodies↗

PubMed1979

[Utilization of feed energy by growing pigs. 3. Energy requirement for the growth and fattening of pigs].

The test series for the investigation of the energy consumption of growing pigs of the breeds large white and improved land race pig as well as cross breeds of the two breeds in a total of 369 metabolism periods (as described in the first two pieces of information of this publication series -- Hoffmann and others, 1977 and Jentsch and Hoffmann, 1977) were statistically analysed for the purpose of the derivation of the energy requirement for maintenance and the partial energy requirement for growth in order to test the possibilities of the factorial analysis for the derivation of energy requirement values of growing pigs. The dependence of the maintenance requirement of growing pigs (investigations in the live weight range of 10 to 40 kg -- see 1st information--were made with boars those in the live weight range of 30 to 120 kg were made with gelded boars, 2nd information) on the live weight can best be characterised by applying a power exponent of 0,61 or 0,62 for the live weight. A definition is offered to be discussed for the energetic maintenance requirement of productive live stock and laboratory animals as a conventional value. The energy requirement values derived from the doubly-factorial statistical analysis show a satisfactory adaptation to the measured values as such concerning energy intake and observed growth performance of the test animals. The conclusion is drawn that the factorial analysis of the energy requirement (maintenance plus partial performances) results in a better estimate of the requirement of growing animals than the assessment according only to live weight and live weight increase without characterising the energy requirement for partial performances. This is important for the further working on and more exact definition of requirement norms.

Animal Feed↗

PubMed1978

[Energy metabolism and energy requirements of growing boars].

The nitrogen and energy metabolism and the energy consumption of growing boars were measured in 2 metabolic and feeding trials using 8 parallel animals each. The studies covered the 30 to 150 kg live weight range. The growth intensity of the boars was found strongly influenced by the protein level of the ration. At a crude protein level of 18% in the ration, the boars gained, on the average, 780 g per day during the fattening period under study. Energy conversion was found to decline as the protein amount went up. The energy expediture for protein deposition was estimated at 1.8 to 2.0 kcal metabolizable energy per kg deposited. The energy and feed expenditures were calculated to be 7.1 Mcal net energy--fat retention for the whole development period or 3.0 kg dry matter per kg live weight. Boars proved to have an energy requirement differing from that of barrows and gilts; equations are presented for derivation.

Animals↗

PubMed1977

[Studies of the energy and crude protein requirements of young fattening geese. 1. Influence of varying energy and crude protein levels in the feed on fattening performance parameters].

In 5 trials using a total of 5367 geese (Deutsche Legagans male X White Italian Goose female), the influence of varying energy and crude protein levels in the feed on fattening performance was studied. After a uniform 4-week starter period (1st to 28th days of life) rations with conventional components were fed, their energy and crude protein levels ranging from 500 to 620 energetic feed equivalents (poultry) and 140 to 180 g CP, respectively. Subsequently, a test under commercial conditions was made to compare the optimal variant found (530 energetic feed equivalents-poultry/175 g CP) with a high-energy feed (620 energetic feed equivalents/175 g CP). As the energy concentration of the feed increased the live weight was not found to rise but slightly. At all energy levels under study, increasing crude protein from 140 to 180 g/5g resulted in higher gains. Feed expenditure was found to decrease as the energy concentration of the rations went up. High energy expenditure did not produce but slightly higher weight gains. Fattening beyond 56 days resulted in considerably higher energy expenditure.

Amino Acids↗

PubMed1978

Energy metabolism of Rickettsia typhi: pools of adenine nucleotides and energy charge in the presence and absence of glutamate.

The obligate intracellular bacterium Rickettsia typhi was examined for its ability to generate and maintain an adenylate energy charge in an extracellular environment. Freshly purified organisms were incubated, at 34 degrees C and pH 7.4, with or without glutamate and various other metabolites, and the levels of ATP, ADP, and AMP were determined. Of the metabolites tested, glutamate and glutamine were the most effective for the generation of ATP. In the presence of glutamate, there was a rapid increase in the level of ATP, followed by a moderate decrease during 150 min of incubation. The energy charge increased from a level of 0.2 to 0.5 to about 0.7 to 0.75, and then slowly declined to about 0.45 to 0.6. In the absence of glutamate, after an occasional initial surge in ATP level as the temperature was changed from 4 to 34 degrees C, there was a sharp decline in both ATP and energy charge (to 0.1 and sometimes to 0.01). The rickettsiae maintained their ability to regenerate their energy charge upon the addition of glutamate for about 30 min, but this ability declined with further incubation. In contrast to Escherichia coli, the decline in ATP in R. typhi was accompanied by a sharp increase in the level of AMP and the total adenylate pool. No adenine or adenosine was recovered from rickettsiae incubated with labeled AMP, ADP, or ATP. From these experiments and the demonstration reported elsewhere that rickettsiae transport the adenine nucleotides, it can be concluded that the adenylate energy charge in R. typhi is governed by the salvage of the adenine nucleotides rather than their unphosphorylated precursors. Thus, R. typhi undergoes greater shifts in energy charge than other bacteria, a phenomenon which may account for their instability in an extracellular environment. Under optimal conditions the adenylate energy charge of R. typhi approaches levels that border on those generally regarded as adequate for growth.

Adenine Nucleotides↗

PubMed1977

Effect of the preceding day's energy intake on the total energy cost of light exercise.

The effect of a variation in the preceding day's dietary energy intake-4, 10 and 18 MJ-on the oxygen consumption and respiratory quotient at rest and at work before and after a test meal (4 MJ) was investigated. 7 normal male subjects were studied at 3 different experimental situations. During the first day the subjects had an energy intake of 10 MJ and normal activity. The following morning measurements of V(O2) and V(CO2) were performed at rest and at work on a bicycle ergometer (36 W) before and after the test meal. The same measurements were performed on the following day but the dietary intake between the two sets of measurement was then either 6, 0 or 14 MJ. No significant effect was found of the preceding day's dietary energy intake on the oxygen consumption or on the energy transformed during rest, during exercise before and after the test meal. The results do not support the conclusions of previously published studies, proposing a significant feed-back mechanism tending to control the body energy content by regulation of the energy expenditure through chemical or mechanical uncoupling.

Adult↗

PubMed1977

Monte Carlo calculations of the energy response of lithium dosemeters to high energy electrons (less than 30 MeV).

Monte Carlo calculations of the energy response of LiF dosemeters have been carried out to help resolve the discrepancy between the measurements of Holt, Edelstein and Clark (1975) and those of Paliwal and Almond (1975) and others. It is concluded that the assumptions used by Holt et al. are largely responsible. They assume, in converting energy deposition in an air-filled ionization chamber to energy deposition in water, that as electrons penetrate a medium they are monoenergetic and the energy is given by Harder's expression (ICRU 1972). The assumption gives poor results as the stopping power for electrons in air is strongly energy dependent, and the energy spectrum has been significantly broadened. The Monte Carlo calculations are also used to criticize the electron cavity theories of Almond and McCray (1970), Burlin, Snelling and Owen (1969) and Holt et al. (1975), and to suggest as an alternative a slightly modified version of the Bragg-Gray theorem.

Electrons↗

PubMed1976

Various types of diets, sources of energy, and positive energy balance in the induction of fatty liver hemorrhagic syndrome.

Adult female chickens were force-fed a corn-soy base diet at 150% of the daily amount consumed by those allowed the same diet ad libitum. Other hens were force-fed diets isocaloric to the 150% group just mentioned, but diet composition was adjusted so that 2/3 of the metabolizable energy (M.E.) came from the corn-soy diet and 1/3 from either corn oil or glucose; or force-fed a low energy diet accounting for 2/3 of the M.E. and corn oil 1/3 of M.E., or a purified diet accounting for all M.E. Fatty liver-hemorrhagic syndrome (FLHS) was induced in all force-fed groups with only the low energy diet plus corn oil having produced a significantly lower score for FLHS. However, the livers from the hens of the latter group had as much lipid, and the hens gained at least as much weight as those in other force-fed groups. During the third week of the experiment M.E. was determined along with a partition of energy among eggs, basal metabolism, body weight gain, and subsistance plus heat increment (H.I). The data showed that the hens force-fed corn oil had lower H.I. values indicative of associative dynamic action of fats at a plane of nutrition above normal. The data revealed that various types of diets and sources of energy in excess can induce FLHS, and this is discussed in terms of FLHS arising out of a positive energy balance.

Animal Feed↗

PubMed1977

Energy transduction in Escherichia coli. The effect of chaotropic agents on energy coupling in everted membrane vesicles from aerobic and anaerobic cultures.

1. The transduction of energy from the oxidation of substrates by the electron transport chain or from the hydrolysis of ATP by the Mg2+-ATPase was measured in everted membrane vesicles of Escherichia coli using the energy-dependent quenching of quinacrine fluorescence and the active transport of calcium. 2. Treatment of everted membranes derived from a wild-type strain with the chaotropic agents guanidine-HC1 and urea caused a loss of energy-linked functions and an increase in the permeability of the membrane to protons, as measured by the loss of respiratory-linked proton uptake. 3. The coupling of energy to the quenching of quinacrine fluorescence and calcium transport could be restored by treatment of the membranes with N,N'-dicyclohyexylcarbodiimide. 4. Chaotrope-treated membranes were found to lack Mg2+-ATPase activity. Binding of crude soluble Mg2+-ATPase to treated membranes restored energy-linked functions. 5. Membranes prepared from a wild-type strain grown under anaerobic conditions in the presence of nitrate retained respiration-linked quenching of quinacrine fluorescence and active transport of calcium after treatment with chaotropic agents. 6. Everted membrane vesicles prepared from an Mg2+-ATPase deficient strain lacked respiratory-driven functions when the cells were grown aerobically but were not distinguishable from membranes of the wild-type when both were grown under anaerobic conditions in the presence of nitrate. 7. It is concluded (a) that chaotropic agents solubilize a portion of the Mg2+-ATPase, causing an increase in the permeability of the membrane to protons and (b) that growth under anaerobic conditions in the presence of nitrate prevents the increase in proton permeability caused by genetic or chemical removal of the catalytic portion of the Mg2+-ATPase.

Adenosine Triphosphatases↗

PubMed1976

Energy requirement of roosters as influenced by environmental temperature, dietary energy and age.

Little information is available on the energy requirement of roosters. The voluntary energy intake is reported for roosters exposed to environmental temperatures of 23, 30 or 37 degrees C. while fed one of three diets differing in energy level. There was a reduction in the energy intake as the environmental temperature increased. The data indicated that the energy requirement was reduced somewhat as the birds get older than 9-10 months of age.

Age Factors↗

PubMed1977

[Behavior of certain parameters of lipid and energy metabolism. IV. Regulation of lipid and energy metabolism in livers and race and mini pigs].

To characterize the lipid and the energy metabolism in the livers of genetically different types of pigs (land race pig and mini pig), the authors determined the activities of enzymes typical of and limiting these metabolic pathways. Furthermore, they measured the concentrations of typical metabolites and ascertained parameters that are of importance in energy metabolism. The concentrations of acetyl CoA and free fatty acids in the livers of mini pigs were significantly greater than those in the livers of land race pigs, whereas the cholesterol, glycerol, triglyceride and acetoacetate concentrations were reduced. The activities of glucose-6-phosphate dehydrogenase (E.C.1.1.1.49.), citrate synthase (E.C.4.1.3.7.) and ATP citrate lyase (E.C.4.1.3.8.) were lower in the livers of mini pigs than in the livers of land race pigs, whereas the activity of fatty acid synthase was higher. The concentrations of cyclic 3',5'-adenosine monophosphate (AMP) and adenosine diphosphate (ADP) were lower in the livers of mini pigs than in those of land race pigs. In land race pigs, the metabolic process seems, therefore, to be determined in favour of the degradation of free fatty acids and of the generation of energy. In mini pigs, lipogenesis in the liver appears to be the decisive metabolic pathway. The possibility of a higher coordinating control mechanism of the lipid and the energy metabolism is discussed.

ATP Citrate (pro-S)-Lyase↗

PubMed1975

Energy-linked and energy-independent transhydrogenase activities in Escherichia coli vesicles.

Active transport vesicles of Escherichia coli were shown to possess low levels of energy-independent and energy-dependent nicotinamide nucleotide transhydrogenase activities. Breakage of such vesicles in a French pressure cell resulted in a fraction which had an 8-10-fold increased respiration- and ATP-driven transhydrogenase activities. Stimulation of the ATPase activity in vesicles with Triton X-100 was also paralledled by a 2-fold increase in the energy-independent transhydrogenase. Disruption of the vesicles similarly resulted in increases in the energy-independent transhydrogenase, NADH and succinate oxidase activities but a decrease in succinate supported proline uptake. In the light of these findings, the "sidedness' of the vesicle membranes is discussed.

Adenosine Triphosphatases↗

PubMed1978

The effects of plane of nutrition and environmental temperature on the energy metabolism of the growing pig. 3. The efficiency of energy utilization for maintenance and growth.

1. From the relation between metabolizable energy (ME) intake and heat loss (H), energy retention (ER), protein (P) and fat (F) deposition the energy costs of maintenance (MEm) and the partial efficiencies of energy retention (k) and protein (kP) and fat (kF) retention were determined in growing pigs at environmental temperatures of 10, 15, 20, 25 or 30 degrees. 2. k decreased with increase in environmental temperature from 0.79 at 10 degrees to 0.63 at 30 degrees with 0.67 at the thermally-neutral temperature of 25 degrees. Each 0.04 decrease in k was associated with a 100 kJ/kg0.75 per d decrease in MEm. Analysis, within several ranges of environmental temperature, suggested a curvilinear relation between ER and ME intake indicating a decrease in k with increase in level of feeding, particularly at thermally-neutral temperatures. 3. Both kP and kF were similar at each environmental temperature and decreased from 0.78 at 10 degrees to 0.63 at 30 degrees. These values are discussed in relation to those predicted from experimentation and it is suggested that the wide range of predicted estimates of kF could be attributed to differences in the rate of protein turnover.

Animal Nutritional Physiological Phenomena↗

PubMed1978

[Energy and crude protein requirements of young fattening geese. 2. Inluence of varying energy and crude protein contents of feed on carcass quality].

In 5 trials using a total of 5,7000 geese (Deutsche Legegans maleXWhite Italian Goose female) of which 482 were slaughtered and subsequently dressed, the influence of varying net energy and crude protein levels in the ration on fattening and carcass performance were studied. Increased crude protein contents were found to improve the meat yield. High-energy feeding likewise caused gains to go up, the extra gain almost exclusively consisting in adipose tissue (particularly skin, and intestinal and abdominal fat). In addition, high energy intakes induced earlier juvenile moulting, this effect making the 56-day old carcasses rather bristly. Therefore, it seems more convenient to fatten geese on low-energy rations (500 energetic feed equivalents/poultry [EFp] per kg) up to the age of 63 days because the meat yield (especially of breast meat) is likely to improve considerably when slaughter takes place at a later date. Goose fattening rations should stick to the following parameters (per kg): 500--550 EFp, 160--180 g crude protein, 8 g lysine, 6.5 g thio-amino acids.

Animal Feed↗