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Results for “energy optimization”

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At least 1,099 records · Page 61Linked to original sources

PubMed1993

Why women gain weight with adjuvant chemotherapy for breast cancer.

PURPOSE: Among breast cancer patients receiving adjuvant chemotherapy, weight gain is a common side effect that may decrease quality of life and potentially threaten survival. Weight gain during treatment is a problem that is clinically well appreciated, and one that has been studied by a number of investigators. DESIGN: A literature review was conducted to address each of the following issues: (1) the prevalence and magnitude of weight gain in women receiving adjuvant chemotherapy for early-stage breast cancer, (2) factors that might affect the amount of weight gained, (3) adverse consequences of weight gain, (4) mechanisms potentially responsible for weight gain, and (5) current dietary intervention programs directed toward women receiving adjuvant chemotherapy. RESULTS: Weight gain is associated with a number of adverse effects in breast cancer patients receiving adjuvant chemotherapy. Weight gains are exaggerated in premenopausal women and women receiving multiagent regimens. Little research has been conducted to investigate the underlying mechanisms that contribute to weight gain in this population. CONCLUSION: Interventions to prevent weight gain during adjuvant chemotherapy are underway; however, little research has been conducted to investigate the underlying mechanisms of energy imbalance. Although changes in resting metabolic rate, thermogenesis, physical activity, and dietary intake are all plausible, no firm data exist to support any of these mechanisms. There is a need for research that explores the relative contribution of each of these factors to energy imbalance, so that optimally effective interventions can be created and implemented to combat this problem.

Breast Neoplasms↗

PubMed2005

Diet and exercise for weight loss: a review of current issues.

Obesity is a fast growing epidemic that is primarily due to environmental influences. Nutrition and exercise represent modifiable factors with a major impact on energy balance. Despite considerable research, there remains continued debate regarding the energy content and the optimal macronutrient distribution for promoting healthy and effective weight loss. Low-fat diets have been advised for many years to reduce obesity. However, their effectiveness has been recently challenged, partly because the prevalence of obesity continues to rise despite reductions in fat intake. There are also concerns regarding the methodology of clinical trials showing benefits of fat reduction on weight loss. Although often viewed as a fad diet, very low-carbohydrate (ketogenic) diets are very popular and several recent clinical trials indicate they are more effective at promoting short-term weight loss and improving characteristics of the metabolic syndrome than low-fat diets. However, there is a need to obtain long-term safety and efficacy data. Clearly, weight loss can be achieved with a variety of diet interventions but the effects on other health-related aspects also need to be considered and studied in more detail. Exercise can have positive effects on weight loss, weight control and overall general health, although debate exists concerning the most effective mode, duration and intensity of exercise required to achieve these effects. Importantly, any effective weight control treatment must consider a life-long plan or there will likely be weight regain. Perhaps the most challenging, but rewarding, question that faces researchers is how to predict individual responses to diet and exercise interventions.

Diet, Reducing↗

PubMed2005

Hormonal responses and adaptations to resistance exercise and training.

Resistance exercise has been shown to elicit a significant acute hormonal response. It appears that this acute response is more critical to tissue growth and remodelling than chronic changes in resting hormonal concentrations, as many studies have not shown a significant change during resistance training despite increases in muscle strength and hypertrophy. Anabolic hormones such as testosterone and the superfamily of growth hormones (GH) have been shown to be elevated during 15-30 minutes of post-resistance exercise providing an adequate stimulus is present. Protocols high in volume, moderate to high in intensity, using short rest intervals and stressing a large muscle mass, tend to produce the greatest acute hormonal elevations (e.g. testosterone, GH and the catabolic hormone cortisol) compared with low-volume, high-intensity protocols using long rest intervals. Other anabolic hormones such as insulin and insulin-like growth factor-1 (IGF-1) are critical to skeletal muscle growth. Insulin is regulated by blood glucose and amino acid levels. However, circulating IGF-1 elevations have been reported following resistance exercise presumably in response to GH-stimulated hepatic secretion. Recent evidence indicates that muscle isoforms of IGF-1 may play a substantial role in tissue remodelling via up-regulation by mechanical signalling (i.e. increased gene expression resulting from stretch and tension to the muscle cytoskeleton leading to greater protein synthesis rates). Acute elevations in catecholamines are critical to optimal force production and energy liberation during resistance exercise. More recent research has shown the importance of acute hormonal elevations and mechanical stimuli for subsequent up- and down-regulation of cytoplasmic steroid receptors needed to mediate the hormonal effects. Other factors such as nutrition, overtraining, detraining and circadian patterns of hormone secretion are critical to examining the hormonal responses and adaptations to resistance training.

Adaptation, Physiological↗

PubMed2006

Physical activity levels of children during school playtime.

School represents a suitable setting for intervention programmes aiming to promote physical activity to benefit health. During the school day, physical education and school playtime offer children regular opportunities to engage in physical activity. However, there is growing concern that, internationally, curricular time allocated to physical education is not meeting statutory guidelines. The effectiveness of the playground environment to promote physical activity has been considered as a complementary setting to physical education. Physical activity guidelines state that children should engage in at least 1 hour of moderate intensity physical activity a day. Currently no empirically tested guidelines exist for physical activity levels during playtime. However, studies cited in this article indicate that playtime can contribute between 5-40% of recommended daily physical activity levels when no interventions have been utilised. The limited school-based investigations that have been reported in the literature suggest that boys engage in more physical activity during playtime than girls. Studies that have implemented intervention strategies in order to promote physical activity levels indicate that playtime can substantially contribute towards daily optimal physical activity guidelines. Energy expenditure and physical activity levels have increased during playtime following the implementation of playtime-based interventions. In order to advance knowledge of children's physical activity during playtime, a number of key issues for consideration in future research are detailed. Research on children's use of playtime to be physically active and the extent of the contribution of playtime to daily physical activity guidelines is warranted.

Child↗

PubMed1988

'Entero-insular axis' and surgical trauma.

To study the optimal means of postoperative energy supply, three glucose loads (5 g, 15 g, 40 g) were given via the enteral or the parenteral route before and immediately after abdominal surgery. Pre- and post-operatively, glucose and insulin concentrations were strongly dose-related after both kinds of administration. But the postoperative insulin concentrations were higher than the preoperative ones. Likewise, in both test situations the 'insulinogenic index' was significantly higher postoperatively than preoperatively. After the enteral glucose load, however, the index was 3 to 10 times higher than after the parenteral one. According to these results, even in the early postoperative period the enteral route of glucose administration is not only feasible but seems also to be superior to the parenteral one.

Adult↗

PubMed1979

Radiation beam characteristics of a 22 MeV microtron.

The properties of the electron and photon beams from a 22 MeV clinical microton are presented. Favourable isodose distributions for radiation therapy are obtained for both modalities. For the electron beam this is accomplished using a dual scattering foil system in which the secondary foil is shaped to optimize uniformity and minimize energy loss and energy straggling. The photon beam is flattened by a composite filter to produce dose distributions of high uniformity over a wide depth interval.

Electrons↗

PubMed2002

Effect of dietary protein on prepubertal mammary development in rapidly growing dairy heifers.

The objective was to determine whether increased dietary protein would enhance mammary development in prepubertal heifers fed for rapid body growth (1.2 kg/d). Fifty-four Holstein heifers (weighing approximately 134 kg) were assigned to one of three treatments. Heifers were fed a total mixed ration with metabolizable energy at 2.85 Mcal/kg and metabolizable protein at low, standard, or high concentrations (37, 41, or 44 g/Mcal of metabolizable energy, respectively) from 3.5 mo of age until slaughter at approximately 46 d after puberty. Heifers fed low, standard, and high protein gained 1130, 1170, and 1180 g/d, respectively. Dietary protein did not affect age or weight of heifers at puberty or slaughter, withers height gain, or carcass composition. Average mammary parenchymal DNA content for heifers on diets of low, standard, and high protein was 595, 619, and 670 mg/100 kg of body weight, respectively, and was not significantly different. However, for heifers that attained puberty early, those fed low protein had 33% less parenchymal DNA than those fed high protein, even though their body growth and carcass composition were not compromised. We conclude that dietary protein does not have a major effect on mammary development of rapidly grown prepubertal heifers, provided the diet contains adequate protein for normal body growth. But we suggest that feeding low-protein diets increases the risk of impaired mammary development when heifers are fed for rapid growth and attain puberty early and that the new National Research Council guidelines for protein relative to energy seem adequate for optimal mammary development.

Aging↗

PubMed2002

Modified techniques of heterotopic total small intestinal transplantation in rats.

AIM: To establish a successful model of heterotopic total small intestinal transplantation (SIT) in rats in order to reduce the complications and increase the survival rate. METHODS: A total of 196 Wistar rats underwent heterotopic SIT with microsurgical technique. Technical modifications included shortening fasting time and supplying energy before surgery, administering optimal volume of crystalloid fluid to the donor and recipient during surgical procedures, reducing mechanical and ischemic injuries to donor intestine, revascularizing small intestinal graft with a combination of conventional aorta to aorta anastomosis and a cuffed portal vein to left renal vein anastomosis which resulted in an acceptably short warm ischemic time, and also an adequate blood supply and drainage of the graft. RESULTS: The average time for the donor surgery was 86 min +/- 20 min, the mean operative time for the recipient was 115 min +/-20 min and warm ischemia time was shortened to 40 min +/- 5 min. There was a shorter revascularizing time of the graft, the abdominal aorta (AA) to AA anastomosis being 21 min +/- 10 min, and the cuffed portal vein (PV) to the renal vein anastomosis being 5 min +/- 5 min. The one-week survival rate of 98 rats with SIT was 88.78% (87/98), without thrombosis and stenosis of anastomosis. The longest survival time of recipient rats was more than 389 days after SIT, the rats were maintaining normal weight, with perfect intestinal function and intact intestinal histology. CONCLUSION: These modified techniques for SIT would remarkably reduce the complications and improve survival rate in rats, which provided a potentially more consistent and practical model for experimental and clinical studies.

Animals↗

PubMed1994

The Canadian National Calibration Reference Centre for In-Vivo Monitoring: thyroid monitoring. Part III: A basic calibration procedure for thyroid monitoring.

This article is the third of a five-part series covering various aspects of occupational thyroid monitoring. This article introduces the basic concepts required to understand the procedure for determining the counting efficiency of a thyroid detector. The B.R.M.D. thyroid-neck phantom is used as the calibration source. A procedure for personnel monitoring is also discussed and the concept of Minimum Detectable Activity (MDA) is introduced. The last two articles in this series discuss energy calibration, counting system optimization based on a single-channel analyzer and placement error minimization.

Calibration↗

PubMed2000

Application of mass and energy balance regularities in fermentation. Reprinted from Biotechnology and Bioengineering, Vol. XX, No. 10, Pages 1595-1621 (1978).

Material and energy balances for fermentation processes are developed based on the facts that the heat of reaction per electron transferred to oxygen for a wide variety of organic molecules, the number of available electrons per carbon atom in biomass, and the weight fraction carbon in biomass are relatively constant. Mass-energy balance equations are developed which relate the biomass energetic yield coefficient to sets of variables which may be determined experimentally. Organic substrate consumption, biomass production, oxygen consumption, carbon dioxide production, heat evolution, and nitrogen consumption are considered as measured variables. Application of the balances using direct and indirect methods of yield coefficient estimation is illustrated using experimental results from the literature. Product formation is included in the balance equations and the effect of product formation on biomass yield estimates is examined. Application of mass-energy balances in the optimal operation of continuous single-cell protein production facilities is examined, and the variation of optimal operating conditions with changes in yield are illustrated for methanol as organic substrate.

Electrons↗

PubMedDate not supplied

[Computer model of 3D structure of cytochrome P450 2B4].

Cytochromes P450 (CYPs) play an important role in the oxidative metabolism of xenobiotics. Three-dimensional structures of CYPs are needed to study structure-function relationships in their molecules and interaction with partner proteins. Experimental determination of eucaryotic CYPs 3D structures is difficult because of hydrophobic membrane anchors and surface hydrophobic regions that prevent their crystallization. Replacement of surface hydrophobic amino acids by hydrophilic residues without any changes in protein structure and function can help to solve this problem. Such modification can be proposed using the analysis of 3D model of protein. In this work computer aided 3D structure of microsomal P450 2B4 (CYP2B4) was modeled for the further prediction of surface mutations for hydrophilization of the protein surface. The model of 3D structure of CYP2B4 was constructed by homology with CYP2C5 Model optimization was made by energy minimization and molecular dynamics simulation of protein molecule in water environment. The model was verified by using special statistic software and by comparison with the experimental data on the substrate recognition site, redox-partner binding sites and chemical modification of the protein surface.

Amino Acid Sequence↗

PubMed2003

Protein threading by linear programming.

Protein three-dimensional structure prediction through threading approach has been extensively studied and various models and algorithms have been proposed. In order to further explore ways to improve accuracy and efficiency of the threading process, this paper investigates the effectiveness of a new method: protein threading via linear programming. Based on the contact map model of protein 3D structure, we formulate the protein threading problem as a large scale integer programming problem, then relax to a linear programming problem, and finally solve the integer program by a branch-and-bound method. The final solution is optimal with respect to energy functions incorporating pairwise interaction and allowing variable gaps. The algorithm has been implemented as software package RAPTOR--RApid Protein Threading predictOR. Experimental results for fold recognition show that RAPTOR significantly outperforms other programs at the fold similarity level. The RAPTOR webserver is at http://www.cs.uwaterloo.ca/-j3xu/RAPTOR_form.htm.

Algorithms↗

PubMedDate not supplied

[Computer module design of the parametric structure of water].

The algorithms of module design and the results of constructing the parametric structures of water were considered. The tetrahedral electron structure of the oxygen atom of water, which is a double symmetric donor and acceptor of protons, was taken as the main postulate. As opposed to the crystal lattices of diamond and ice, the hexacycle twist-bath was considered as the basic element of the original structure. A great variety of possible structures were obtained, which involve quasi-unidimensional (helices, rods), dendrite-like, ring-shaped, planar, and fractal structures, as well as combinatoric structures composed of these forms. The functions of distribution of valence angles in fractal structures optimized with respect to energy have two main maxima at 104 and 112 degrees, as differentiated from the starting ideal tetrahedral angle of 109.5 degrees. Changes in, and the accumulation of elastic energy of distortions of rod structure of different symmetry were analyzed. This energy can be utilized during the conformational changes of biopolymers. The substantial difference in the solubility of two anomeric forms of glucose is explained by a different degree of conformity of the glucose molecule structure to the structure of bound water.

Computer Simulation↗

PubMedDate not supplied

[The effect of the fluctuations of abiotic factors on the metabolism of some hydrobionts].

It has been shown that slight sinusoidal fluctuations of temperature, salinity, and oxygen concentration optimize the growth and energy metabolism of the crustacean Leander modestus, mollusks Pila sp., and hydrophyte Elodea canadensis. Under the effect of temperature fluctuations, the growth of E. canadensis accelerates, and the rate of photosynthesis increases.

Animals↗

PubMed2004

A comparison of ultrasound treatment on primary and secondary sludges.

Ultrasound treatment of primary and secondary sludges was conducted to improve the qualities of sludges for the anaerobic digestion. The impacts of different sonication times, sonication densities and solids concentrations on ultrasonication efficiency were examined. The experimental results indicated that the significant reduction in particle size and increase in soluble organics could be achieved, implying that ultrasonication could offer a feasible treatment method to efficiently disintegrate sludge. The greater decrease in particle size and increase in soluble organics of sludge indicated that the secondary sludge has a more remarkable improvement after sonication over the primary sludge. With respects to the extent of disintegration and energy consumption, higher sonication density performed more effectively in terms of specific energy. There exists an optimal solids concentration range for both the sludges for optimum sonication. Within the optimal solids concentration range, efficient sonication can be effected and sludge would be disintegrated efficiently. The ultrasound would be attenuated by scattering and absorption if the solids concentration exceeds the optimal range. It appeared from the study that the mechanical shear forces caused by ultrasonic cavitation could be a key factor for sludge disintegration and collapse of cavitation bubbles could significantly alter the sludge characteristics.

Particle Size↗

PubMed1991

[Laser seromyotomy of the stomach in duodenal ulcers].

The use of laser surgical equipment permits to simplify considerably a method of gastric seromyotomy. On the basis of the results of treating 38 patients, the optimal parameters of laser energy, used in dissection of the gastric wall, are recommended, the advantages and shortcomings of the different sources of radiation are studied.

Duodenal Ulcer↗

PubMed1986

[Electroshock (cardioversion) treatment problems in rhythm disorders].

Some problems associated with the results from the electroshock treatment of 1027 patients with rhythm disorders are discussed, as well as the choice of the necessary quantity of electric energy and the way of preparation of the patients. It was established, that sinus rhythm restoration was attained in 90.1% under planned conditions, and in emergency cases--in 86.9%. The highest percentage of positive results were obtained with atrial fibrillation (95.6), and the lowest--with paroxysmal supraventricular tachycardia (97.7). The results is identical (88%) with ventricular tachycardia and atrial flutter. The duration of the rhythm disorder is of importance for the result, being the best up to the third month after the origination of the disorder, but good results had been obtained with a longer duration. The quantity of energy from 200 to 300 W/s (median 250 W/s) was outlined as optimal. The mean quantity of electric energy used in atrial flutter was 278.8 +/- 51.7, in paroxysmal supraventricular tachycardia--246.3 +/- 57.8 in atrial fibrillation--229.5 +/- 40.7 and in ventricular tachycardia--182.9 +/- 37.5 W/s. The anticoagulant prophylaxis is carried out in the patients with a longer duration of the rhythm disorder, in the patients with heart defects and those with ischemic heart disease (with eventual aneurysm). There was a single pre-treatment with quinidine--0.20 or 0.40.

Aging↗

PubMed1979

[Respiratory responses to different human movements].

Respiratory responses to different movements and postures become stabilized according to the respiratory-energy demands of the optimal way for task solution. Passive pedalling entails diminishing of electrical activity, the respiratory reactions at that being significantly higher than at resting but lower as compared to active work. With no circumstantial (sporting) stimuli, the increase of respiratory responses to muscular relaxation in the course of pedalling was as significant as the cardiac outflow volume. Maximal and minimal values of the blood pressure did not change. The circumstantial conditioned stimuli enhanced the respiratory responces both at resting and during passive pedalling.

Blood Pressure↗