Blood loss during liver transplantation (OLTx) is a common consequence of pre-existing abnormalities of the hemostatic system,portal hypertension with multiple collateral vessels,portal vein thrombosis,previous abdomi...Blood loss during liver transplantation (OLTx) is a common consequence of pre-existing abnormalities of the hemostatic system,portal hypertension with multiple collateral vessels,portal vein thrombosis,previous abdominal surgery,splenomegaly,and poor "functional" recovery of the new liver.The intrinsic coagulopathic features of end stage cirrhosis along with surgical technical difficulties make transfusion-free liver transplantation a major challenge,and,despite the improvements in understanding of intraoperative coagulation profiles and strategies to control blood loss,the requirements for blood or blood products remains high.The impact of blood transfusion has been shown to be significant and independent of other well-known predictors of posttransplant-outcome.Negative effects on immunomodulation and an increased risk of postoperative complications and mortality have been repeatedly demonstrated.Isovolemic hemodilution,the extensive utilization of thromboelastogram and the use of autotransfusion devices are among the commonly adopted procedures to limit the amount of blood transfusion.The use of intraoperative blood salvage and autologous blood transfusion should still be considered an important method to reduce the need for allogenic blood and the associated complications.In this article we report on the common preoperative and intraoperative factors contributing to blood loss,intraoperative transfusion practices,anesthesiologic and surgical strategies to prevent blood loss,and on intraoperative blood salvaging techniques and autologous blood transfusion.Even though the advances in surgical technique and anesthetic management,as well as a better understanding of the risk factors,have resulted in a steady decrease in intraoperative bleeding,most patients still bleed extensively.Blood transfusion therapy is still a critical feature during OLTx and various studies have shown a large variability in the use of blood products among different centers and even among individual anesthesiologists within the same center.展开更多
At a global scale, cereal yields and fertilizer N consumption have increased in a near-linear fashion during the past 40 years and are highly correlated with one another. However,large differences exist in historical ...At a global scale, cereal yields and fertilizer N consumption have increased in a near-linear fashion during the past 40 years and are highly correlated with one another. However,large differences exist in historical trends of N fertilizer usage and nitrogen use efficiency (NUE)among regions, countries, and crops. The reasons for these differences must be understood to estimate future N fertilizer requirements. Global nitrogen needs will depend on: (i) changes in cropped cereal area and the associated yield increases required to meet increasing cereal demand from population and income growth, and (ii) changes in NUE at the farm level. Our analysis indicates that the anticipated 38% increase in global cereal demand by 2025 can be met by a 30% increase in N use on cereals, provided that the steady decline in cereal harvest area is halted and the yield response to applied N can be increased by 20%. If losses of cereal cropping area continue at the rate of the past 20 years (-0.33% per year) and NUE cannot be increased substantially, a 60% increase in global N use on cereals would be required to meet cereal demand. Interventions to increase NUE and reduce N losses to the environment must be accomplished at the farm- or field-scale through a combination of improved technologies and carefully crafted local policies that contribute to the adoption of improved N management; uniform regional or national directives are unlikey to be effective at both sustaining yield increases and improving NUE. Examples from several countries show that increases in NUE at rates of 1% per year or more can be achieved if adequate investments are made in research and extension. Failure to arrest the decrease in cereal crop area and to improve NUE in the world's most important agricultural systems will likely cause severe damage to environmental services at local, regional, and global scales due to a large increase in reactive N load in the environment.展开更多
Amino acids are building blocks for proteins in all animals. Based on growth or nitrogen balance, amino acids were traditionally classified as nutritionally essential or nonessential for mammals, birds and fish. It wa...Amino acids are building blocks for proteins in all animals. Based on growth or nitrogen balance, amino acids were traditionally classified as nutritionally essential or nonessential for mammals, birds and fish. It was assumed that all the ＂nutritionally nonessential amino acids （NEAA）＂ were synthesized sufficiently in the body to meet the needs for maximal growth and optimal health. However, careful analysis of the scientific literature reveals that over the past century there has not been compelling experimental evidence to support this assumption. NEAA （e.g., glutamine, glutamate, proline, glycine and arginine） play important roles in regulating gene expression, cell signaling, antioxidative responses, fertility, neurotransmission, and immunity. Additionally, glutamate, glutamine and aspartate are major metabolic fuels for the small intestine to maintain its digestive function and to protect the integrity of the intestinal mucosa. Thus, diets for animals must contain all NEAA to optimize their survival, growth, development, reproduction, and health. Furthermore, NEAA should be taken into consideration in revising the ＂ideal protein＂ concept that is currently used to formulate swine and poultry diets. Adequate provision of all amino acids （including NEAA） in diets enhances the efficiency of animal production. In this regard, amino acids should not be classified as nutritionally essential or nonessential in animal or human nutrition. The new Texas A＆M University＇s optimal ratios of dietary amino acids for swine and chickens are expected to beneficially reduce dietary protein content and improve the efficiency of their nutrient utilization, growth, and production performance.展开更多
文摘Blood loss during liver transplantation (OLTx) is a common consequence of pre-existing abnormalities of the hemostatic system,portal hypertension with multiple collateral vessels,portal vein thrombosis,previous abdominal surgery,splenomegaly,and poor "functional" recovery of the new liver.The intrinsic coagulopathic features of end stage cirrhosis along with surgical technical difficulties make transfusion-free liver transplantation a major challenge,and,despite the improvements in understanding of intraoperative coagulation profiles and strategies to control blood loss,the requirements for blood or blood products remains high.The impact of blood transfusion has been shown to be significant and independent of other well-known predictors of posttransplant-outcome.Negative effects on immunomodulation and an increased risk of postoperative complications and mortality have been repeatedly demonstrated.Isovolemic hemodilution,the extensive utilization of thromboelastogram and the use of autotransfusion devices are among the commonly adopted procedures to limit the amount of blood transfusion.The use of intraoperative blood salvage and autologous blood transfusion should still be considered an important method to reduce the need for allogenic blood and the associated complications.In this article we report on the common preoperative and intraoperative factors contributing to blood loss,intraoperative transfusion practices,anesthesiologic and surgical strategies to prevent blood loss,and on intraoperative blood salvaging techniques and autologous blood transfusion.Even though the advances in surgical technique and anesthetic management,as well as a better understanding of the risk factors,have resulted in a steady decrease in intraoperative bleeding,most patients still bleed extensively.Blood transfusion therapy is still a critical feature during OLTx and various studies have shown a large variability in the use of blood products among different centers and even among individual anesthesiologists within the same center.
文摘At a global scale, cereal yields and fertilizer N consumption have increased in a near-linear fashion during the past 40 years and are highly correlated with one another. However,large differences exist in historical trends of N fertilizer usage and nitrogen use efficiency (NUE)among regions, countries, and crops. The reasons for these differences must be understood to estimate future N fertilizer requirements. Global nitrogen needs will depend on: (i) changes in cropped cereal area and the associated yield increases required to meet increasing cereal demand from population and income growth, and (ii) changes in NUE at the farm level. Our analysis indicates that the anticipated 38% increase in global cereal demand by 2025 can be met by a 30% increase in N use on cereals, provided that the steady decline in cereal harvest area is halted and the yield response to applied N can be increased by 20%. If losses of cereal cropping area continue at the rate of the past 20 years (-0.33% per year) and NUE cannot be increased substantially, a 60% increase in global N use on cereals would be required to meet cereal demand. Interventions to increase NUE and reduce N losses to the environment must be accomplished at the farm- or field-scale through a combination of improved technologies and carefully crafted local policies that contribute to the adoption of improved N management; uniform regional or national directives are unlikey to be effective at both sustaining yield increases and improving NUE. Examples from several countries show that increases in NUE at rates of 1% per year or more can be achieved if adequate investments are made in research and extension. Failure to arrest the decrease in cereal crop area and to improve NUE in the world's most important agricultural systems will likely cause severe damage to environmental services at local, regional, and global scales due to a large increase in reactive N load in the environment.
基金supported by National Research Initiative Competitive Grants from the Animal Reproduction Program(2008-35203-19120 and 2011-67015-20028)Animal Growth&Nutrient Utilization Program(2008-35206-18764, 2008-35206-18762,2009-35206-05211,and 2014-67015-21770) of the USDA National Institute of Food and Agriculture Texas A&M AgriLife Research(H-8200),Ajinomoto Inc.(Tokyo,Japan),and Gentech Inc. (Shanghai,China)
文摘Amino acids are building blocks for proteins in all animals. Based on growth or nitrogen balance, amino acids were traditionally classified as nutritionally essential or nonessential for mammals, birds and fish. It was assumed that all the ＂nutritionally nonessential amino acids （NEAA）＂ were synthesized sufficiently in the body to meet the needs for maximal growth and optimal health. However, careful analysis of the scientific literature reveals that over the past century there has not been compelling experimental evidence to support this assumption. NEAA （e.g., glutamine, glutamate, proline, glycine and arginine） play important roles in regulating gene expression, cell signaling, antioxidative responses, fertility, neurotransmission, and immunity. Additionally, glutamate, glutamine and aspartate are major metabolic fuels for the small intestine to maintain its digestive function and to protect the integrity of the intestinal mucosa. Thus, diets for animals must contain all NEAA to optimize their survival, growth, development, reproduction, and health. Furthermore, NEAA should be taken into consideration in revising the ＂ideal protein＂ concept that is currently used to formulate swine and poultry diets. Adequate provision of all amino acids （including NEAA） in diets enhances the efficiency of animal production. In this regard, amino acids should not be classified as nutritionally essential or nonessential in animal or human nutrition. The new Texas A＆M University＇s optimal ratios of dietary amino acids for swine and chickens are expected to beneficially reduce dietary protein content and improve the efficiency of their nutrient utilization, growth, and production performance.
