Macronutrients,minerals, vitamins and energy

Carbohydrates have the general formula C_n(H₂O)_n. Monosaccharides have between three and six carbon atoms and exist as chains or ring structures. As rings, they link with other monosaccharide rings. The major carbohydrate in humans is glucose, which is stored as glycogen: branching chains of glucose molecules. Fat (triglyceride), which makes up adipose tissue, consists of three fatty acids bonded to glycerol, but other lipids include phospholipids and steroids. Proteins are composed of chains of amino acids linked by amide bonds folded on each other to form protein structures. Vitamins and minerals are obtained from the diet and are required in varying quantities for a variety of metabolic processes. Energy is derived from the oxidation of carbohydrate, fat and protein. Energy expenditure and substrate oxidation can be calculated from oxygen consumption, carbon dioxide production and urinary nitrogen excretion.     

Macronutrients,minerals, vitamins and energy

Macronutrients comprise carbohydrates, fats and proteins and make up most of the body's soft tissue structure. Carbohydrates are organic molecules made of carbon, hydrogen and oxygen atoms. Fats are composed of carbon, hydrogen and oxygen, but the proportion of oxygen atoms to carbon and hydrogen is lower than in carbohydrates. Proteins are usually made up of more than 100 amino acids linked into chains by peptide bonds. Amino acids consist of an asymmetrical carbon atom with both an amino group (NH₂) and a carboxyl group (COOH) attached. Energy used for metabolic homeostasis, thermoregulation, physical activity and normal organ function is obtained from the oxidation of these macronutrients. Micronutrients (trace minerals and vitamins) are dietary components necessary to sustain health. Most trace minerals appear to function as cofactors for a number of enzymes. Vitamins have many roles in intermediary metabolism and in the specialized metabolism of specifc organs.     

Macronutrients,minerals, vitamins and energy

Protein, carbohydrates and fats are collectively known as macronutrients. Their chemical energy can be liberated by oxidation and they are the building blocks for the human body. Micronutrients include vitamins and trace minerals and are required in much smaller quantities than macronutrients, but play vital roles in maintaining optimum health. Although many of their exact functions remain elusive, micronutrient deficiencies cause characteristic diseases. Energy expenditure can be measured using direct or indirect calorimetry, or estimated using specific formula. Daily energy and macronutrient requirements change during illness.     

Macronutrients,minerals, vitamins and energy

Carbohydrates have the general formula C_n(H₂O)_n. Monosaccharides have between three and six carbon atoms and exist as chains or ring structures. As rings, they link with other monosaccharide rings. The major carbohydrate in humans is glucose, which is stored as glycogen: branching chains of glucose molecules. Fat (triglyceride), which makes up adipose tissue, consists of three fatty acids bonded to glycerol, but other lipids include phospholipids and steroids. Proteins are composed of chains of amino acids linked by amide bonds folded on each other to form protein structures. Vitamins and minerals are obtained from the diet and are required in varying quantities for a variety of metabolic processes. Energy is derived from the oxidation of carbohydrate, fat and protein. Energy expenditure and substrate oxidation can be calculated from oxygen consumption, carbon dioxide production and urinary nitrogen excretion.     

恶性肿瘤病人能量消耗及机体组成变化测定

目的测定恶性肿瘤病人静息能量消耗（REE）、底物氧化及机体组成,探讨能量消耗与底物代谢的关系。方法间接测热法测定复旦大学附属中山医院2006年9月至2008年3月714例恶性肿瘤病人和642例良性疾病对照人群REE、碳水化合物氧化率 (CO)、脂肪氧化率(FO)。生物电阻抗法测定细胞内水（ICF）、细胞外水（ECF）、总体水（TW）、脂肪群(FM)、非脂肪群(FFM)。结果恶性肿瘤组与对照组相比,mREE/FFM和mREE/PEE升高;处于较高的能量消耗分布状态;FO升高,CO和npRQ降低;ECF/BW和TW/BW增加,ICF/BW减少;FM和FFM减少,以FM减少为主;BCM减少。结论恶性肿瘤病人总体上具有较高的能量消耗;FO升高,CO和npRQ降低;FM和FFM减少,BCM丢失。ECF/BW和TW/BW增加、ICF/BW减少;能量消耗增加与底物代谢变化有一定关系。     

Intermediary metabolism

Carbohydrate and fat form the immediate and long-term energy stores of the body. Protein constitutes the active (functional) cell mass and is also an energy source but, normally, a relatively minor one. All three macronutrients are interrelated. Proteins are synthesized from amino acids derived from ingested protein. Glucose and fat provide energy via adenosine triphosphate. The brain and red blood cells can only obtain their energy from glucose. Glucose is oxidized via the glycolytic and the tricarboxylic acid (Krebs) cycle pathways. Fatty acids are metabolized by the process of β-oxidation, whereby two carbon fragments are cleaved from the fatty acid chain and enter the Krebs cycle. Amino acids are deaminated to keto acids and the nitrogen moiety excreted in the urine mostly as urea. The keto acids enter the metabolic pathways at various points, mostly in the Krebs cycle. Glucose can be synthesized from lactate, glycerol and amino acids (gluconeogenesis), but not from fatty acids.     

Intermediary metabolism

Carbohydrate and fat form the immediate and long-term energy stores of the body. Protein constitutes the active (functional) cell mass and is also an energy source but, normally, a relatively minor one. All three macronutrients are interrelated. Proteins are synthesized from amino acids derived from ingested protein. Glucose and fat provide energy via adenosine triphosphate. The brain and red blood cells can only obtain their energy from glucose. Glucose is oxidized via the glycolytic and the tricarboxylic acid (Krebs) cycle pathways. Fatty acids are metabolized by the process of β-oxidation, whereby two carbon fragments are cleaved from the fatty acid chain and enter the Krebs cycle. Amino acids are deaminated to keto acids and the nitrogen moiety excreted in the urine mostly as urea. The keto acids enter the metabolic pathways at various points, mostly in the Krebs cycle. Glucose can be synthesized from lactate, glycerol and amino acids (gluconeogenesis), but not from fatty acids.     

Starvation,exercise and the stress response

Starvation, exercise and the stress response have a physiological impact on the body. Many patients are malnourished, have impaired exercise tolerance or undergo the stress response. We describe how the body adapts to decreased nutrient supply, increased energy demands and to stress.     

The effects of dopamine infusion on the postoperative energy expenditure,metabolism, and catecholamine levels of patients after esophagectomy

Although dopamine is one of the most widely used vasoactive agents, its postoperative thermogenic and metabolic effects have not been studied. In this study, the effects of low-dose dopamine, given at 5 /kg/min, on resting energy expenditure (REE), metabolism, and plasma catecholamine levels were examined in eight postsurgical patients. Dopamine infusion increased REE from 1,839 ± 171 kcal/day to 2,071 ±170 kcal/day, and it decreased to 1,867 ± 141 kcal/day after cessation of the infusion. Dopamine also increased the plasma levels of glucagon from 109.4 ± 8.7 pg/ml to 132.5 ±8.0 pg/ml, and it decreased to 102.9 ± 11.1 pg/ml after cessation of the infusion. The plasma levels of dopamine before, during, and after the infusion were 116.1 ± 18.3, 161.1 ±25.6, and 121.4 ± 17.2 ng/ml, respectively. Insulin and glucose were affected by dopamine, but changes in their plasma levels did not parallel the dopamine levels. Epinephrine and norepinephrine were increased by the infusion of dopamine and continued to increase even after its cessation. The results of this study revealed that low-dose dopamine increased REE in postsurgical patients and that this might be associated with the concomitant increase in plasma glucagon.     

Changes in body composition, muscle function and energy expenditure after radical cystectomy

OBJECTIVE

To determine the changes in body composition, muscle function and energy expenditure after radical cystectomy (RC).

PATIENTS AND METHODS

Eleven consecutive men (median age 66 years, range 44–79) who had a RC over a 1‐year period had measurements made of their total body protein, by neutron‐activation analysis, total body water by tritium dilution, total body potassium by whole‐body counting, resting energy expenditure by indirect calorimetry, and grip strength and respiratory muscle strength. These variables were measured on the day before surgery and at 2 weeks and 6 months after RC. Total body fat was derived using a multicompartment model. Artificial nutritional support was not provided after RC and no oral caloric intake was provided until bowel function returned.

RESULTS

Five patients were malnourished before RC and four had significant complications afterward. Over the first 2 weeks there were significant losses in mean (sem ) protein levels, at 0.68 (0.17) kg (P < 0.001) and water, at 3.00 (0.73) L (P < 0.001), while body fat was unchanged. Resting energy expenditure was 11% higher than predicted at 14 days after RC (P < 0.001). Body potassium changes mirrored the protein changes but were not statistically significant. Over the subsequent 6 months, 63%, i.e. 0.43 (0.24) kg, of the body protein lost after surgery was regained. Muscle function had returned to baseline levels at 6 months.

CONCLUSIONS

This study shows that the catabolic loss of body protein after RC is not regained by 6 months. Regimens directed at early nutritional support after RC for these patients might improve the recovery of body composition, with consequent clinical benefits.     

Starvation,exercise and the stress response

Starvation, exercise and the stress response have a physiological impact on the body. Many patients are malnourished, have impaired exercise tolerance or undergo the stress response. We describe how the body adapts to decreased nutrient supply, increased energy demands and to stress.     

Digestion and absorption

Carbohydrates are digested by salivary and pancreatic amylases to di-, tri- and oligosaccharides, and then to monosaccharides by enzymes on the wall of the small intestine to allow them to be absorbed. Proteins are absorbed as amino acids and small peptides that are broken down to amino acids within the cells. Monosaccharides and amino acids pass into the liver via the portal vein. Fats are digested and absorbed as free fatty acids and glycerides that are then mostly reconstituted as triglycerides in the mucosal cells of the small intestine. They combine with phospholipids and a protein to form chylomicrons, which pass via the lymphatics and the thoracic duct into the systemic circulation. Fatty acids are re-esterified and stored as triglycerides in adipose tissue or oxidized for energy. Water is passively absorbed due to the osmotic gradient that results mainly due to the active absorption of sodium ions.     

Intermediary metabolism

Intermediary metabolism refers to the sum of all intracellular chemical processes by which nutritive material is converted into cellular components. It includes anabolism (synthesis of macromolecules) and catabolism (breakdown of macromolecules). Cellular energy is generated from aerobic oxidation of metabolic fuels (carbohydrates, fats, proteins) derived from digestion of a meal or from breakdown of internal stores. These metabolic fuels are broken down into basic substrates (glucose, amino acids, free fatty acids, glycerol). This is followed by processes that remove electrons (oxidation) from these substrates at high potential and transfer them to substrates at lower potential. It is during these processes that energy is released. Reduced coenzymes (NAD⁺ and FADH) are intermediate energy storage compounds that aid electron (and energy) transfer from metabolic reactions (glycolysis and Krebs cycle) to the electron transport chain. In the electron transport chain, electrons are transferred through a series of carriers of lower potential and energy released during this is used to form adenosine triphosphate. These electrons finally combine with the end electron acceptor oxygen, to form water. During aerobic metabolism, oxygen is consumed at the end of electron transport chain producing carbon dioxide via Krebs cycle. However, energy can also be generated anaerobically via glycolysis with the production of lactate.     

Injection of Vitamin A Acid, Vitamin E, and Vitamin C for Treatment of Tissue Necrosis

Experimental studies concerning All-Trans Retinoic acid 0.1% with the antioxidant action of the Vitamin E (tocopherol acetate 0.20%) and Vitamin C (coated ascorbic acid 0.20%) efficacy in both the vascular neoformation induction and cellular membrane stabilization have been conducted by us to improve skin necrosis regression after routine plastic surgeries. Patients after rhytidectomy, breast reduction, and abdominoplasty with localized skin flap necrosis, were submitted to daily intradermic injections for a period of 15 days and had their skin healed by the effects of these vitamins.     

Continuous non-invasive monitoring of energy expenditure, oxygen consumption and alveolar ventilation during controlled ventilation: validation in an oxygen consuming lung model

Background: We have developed a combined indirect calorimetric and breath-by-breath capnographic device (GEM) for respiratory monitoring: oxygen consumption (V?O₂), carbon dioxide excretion (V?CO₂), respiratory quotient (RQ), energy expenditure (EE), alveolar ventilation (V?_A) and dead space/total ventilation (V_D/V_T). Methods: The device was tested in a lung model in which V?O₂ was achieved by combustion of hydrogen. V?CO₂ was achieved by delivering CO₂ into the single alveolus combustion chamber. V?O₂, V?CO₂, compliance, and anatomical dead space could be varied independently. Results: Measured V?O₂ was 101±3% (SD) of set value at a F₁O₂<0.6 and 101±7% at a F₁O₂>0.6 during 15 hours of testing. The corresponding V?CO₂ values were 99±2% and 102±7%. The GEM could with good accuracy measure accumulated energy expenditure (EE) during simulated unstable patient conditions up to a F₁O₂ of 0.8. At F₁O₂ above 0.8 V?CO₂ and V?O₂ could be estimated using a default RQ value of 0.85. On-line estimated V?_A and V_D/V_T values could be obtained at any F₁O₂ up to 1.0. In a test sequence with stable V?O₂ and V?CO₂ the GEM adequately followed changes in V?_A, induced by changes in anatomical dead space, breathing frequency and compliance. Conclusion: The overall performance of the device is satisfactory and well comparable with any equipment tested. It allows near-continuous non-invasive monitoring of EE, V?O₂, V?CO₂, V?_A, V_D/V_T in ventilated, critically ill patients, providing a rationale for ventilator settings and nutritional support.     

Changes in body mass, energy balance, physical function, and inflammatory state in patients with locally advanced head and neck cancer treated with concurrent chemoradiation after low-dose induction chemotherapy

BACKGROUND: We aimed to determine changes in body mass and body composition in relation to energy balance, inflammatory state, and physical function before and after concurrent chemoradiation (CCR). METHODS: Seventeen patients with stage III and IVa head and neck cancer, aged 58.9 +/- 5.4 years, who had completed a 9-week regimen of low-dose induction chemotherapy came to the General Clinical Research Center pre- and post-CCR for measurement of body mass composition by dual-energy X-ray absorptiometry, resting energy expenditure (REE) by indirect calorimetry, physical performance (by Modified Baecke Questionnaire and Reuben's Physical Performance Test), and functionality (Activities and Instrumental Activities of Daily Living scores). Fasting venous samples were collected to determine C-reactive protein and cytokines interleukin (IL)-1beta, IL-6, IL-8, and IL-10. Random 24-hour telephone diet recalls assessed energy intakes. RESULTS: Weight loss began 1 week after CCR. Lean body mass (LBM) accounted for 71.7% +/- 21% of body mass loss. No change occurred in energy intakes or calorie/nitrogen ratio. REE was significantly increased when adjusted for LBM loss (kcal/kg), p = .019. LBM loss was significantly associated with physical performance decline, r = .71, p = .004, and increased functional dependence, r = .58, p = .02. Total physical activity level declined significantly, p = .003. Cytokine levels were strongly associated with physical and functional decline. CONCLUSIONS: The aberrant changes in body composition, metabolism, and inflammatory state were associated with clinically and statistically significant impairments in physical performance and function. Future investigations and clinical practice should combine nutrition with antiinflammatory agents and exercise activities to support lean tissue anabolism and prevent physical and functional decline of patients with head and neck cancer undergoing CCR.     

手足口病患儿线粒体抗病毒蛋白和线粒体融合蛋白1表达及其临床意义

目的 检测线粒体抗病毒蛋白(MAVS)和线粒体融合蛋白1(MFN1)在手足口病(HFMD)患儿的表达水平,探索其在HFMD中的临床意义.方法 选择2017年5月至2019年5月于西安交通大学第二附属医院感染科和西安市儿童医院就诊的82例HFMD患儿作为研究对象,将其按照病情严重程度和感染病原体不同分为EV71重症(18...     

Nutritional status,nutrient intake and use of enzyme supplements in paediatric patients with Cystic Fibrosis; a European multicentre study with reference to current guidelines

Background

The New European guidelines have established the most updated recommendations on nutrition and pancreatic enzyme replacement therapy (PERT) in CF. In the context of MyCyFAPP project - a European study in children with CF aimed at developing specific tools for improvement of self-management - the objective of the current study was to assess nutritional status, daily energy and macronutrient intake, and PERT dosing with reference to these new guidelines.