The Journal of Nutrition back issues from January 2006:
Branched-Chain Amino Acids: Enzyme and Substrate Regulation1-3
Jan 01, 2006; ... ABSTRACT The three branched-chain amino acids (BCAAs) are the most hydrophobic of the amino acids and play crucial roles in determining the structures of globular proteins as well as the interaction of the transmembrane domains of membranous proteins with phospholipid bilayers. However, ...
Structure of the Blood-Brain Barrier and Its Role in the Transport of Amino Acids1-3
Jan 01, 2006; ... ABSTRACT Brain capillary endothelial cells form the blood-brain barrier (BBB). They are connected by extensive tight junctions, and are polarized into luminal (blood-facing) and abluminal (brain-facing) plasma membrane domains. The polar distribution of transport proteins mediates amino ...
Signaling Pathways and Molecular Mechanisms through which Branched-Chain Amino Acids Mediate Translational Control of Protein Synthesis1-3
Jan 01, 2006; ... ABSTRACT BCAAs stimulate protein synthesis in in vitro preparations of skeletal muscle. Likewise, the stimulation of protein synthesis in skeletal muscle produced by intake of a mixed meal is due largely to BCAAs. Of the three BCAAs, leucine is the one primarily responsible for the ...
Investigations of Branched-Chain Amino Acids and Their Metabolites in Animal Models of Cancer1-3
Jan 01, 2006; ... ABSTRACT Many of the features of BCAA metabolism in the tumor-bearing state are similar to the other disease states that feature involuntary weight loss and skeletal muscle atrophy. These states are generally characterized by altered BCAA availability (low BCAA intakes, elevated rates of ...
Metabolism and Physiological Function of Branched-Chain Amino Acids: Discussion of Session 1(1,2)
Jan 01, 2006; ... The discussion was opened by Dr. Harris with comments about important points from his perspective that were made during Dr. Brosnan's presentation: 1) three BCAAs are found in nature because this number of BCAAs provides the diversity in aliphatic hydrophobic side chains needed for the structure ...
The Regulation of Body and Skeletal Muscle Protein Metabolism by Hormones and Amino Acids1-3
Jan 01, 2006; ... ABSTRACT For many decades, it has been recognized that insulin, growth hormone, glucocorticoids, insulin-like growth factor 1, thyroid hormones, and other hormones regulate body protein metabolism. It has been more recently recognized, but not understood, that humor factors present in ...
Modulations of Muscle Protein Metabolism by Branched-Chain Amino Acids in Normal and Muscle-Atrophying Rats1,2
Jan 01, 2006; ... ABSTRACT It has been shown that BCAAs, especially leucine, regulate skeletal muscle protein metabolism. However, it remains unclear how BCAAs regulate muscle protein metabolism and lead to anabolism in vivo. We examined muscle protein synthesis rate and breakdown rate simultaneously ...
Branched-Chain Amino Acid Catabolism in Exercise and Liver Disease1-3
Jan 01, 2006; ... ABSTRACT Branched-chain α-keto acid dehydrogenase (BCKDH) complex, the enzyme catalyst for the second step of the BCAA catabolic pathway, plays a central role in the regulation of BCAA catabolism. The activity of the complex is regulated by a covalent modification cycle in which ...
Application of Branched-Chain Amino Acids in Experimental Animals: Discussion of Session 2(1,2)
Jan 01, 2006; ... This session included talks representing four topic areas: effects of BCAAs on protein synthesis and breakdown in various rodent models (Dr. Kobayashi), metabolism of BCAA in cancer (Dr. Baracos), insights gained from studies of genetic disorders of BCAA metabolism (Dr. Chuang), and BCAA ...
Branched-Chain Amino Acid Requirements in Healthy Adult Human Subjects1-4
Jan 01, 2006; ... ABSTRACT There is now an expanding body of evidence to recommend, in the case of adult humans, the use of revised indispensable amino acid requirement values; these are ~2 to 3 times higher than the current international recommendations. The earlier methodologies for determining amino ...
Lessons from Genetic Disorders of Branched-Chain Amino Acid Metabolism1-3
Jan 01, 2006; ... ABSTRACT Genetic disorders of BCAA metabolism produce amino acidopathies and various forms of organic aciduria with severe clinical consequences. A metabolic block in the oxidative decarboxylation of BCAA caused by mutations in the mitochondrial branched-chain α-keto acid ...
Branched-Chain Amino Acids as Fuels and Anabolic Signals in Human Muscle1-3
Jan 01, 2006; ... ABSTRACT During exercise, there is an increase in amino acid (AA) oxidation accompanied by a depression in whole-body protein synthesis and an increase in protein breakdown. Leucine oxidation increases in proportion to energy expenditure, but the total contribution of BCAA to fuel ...
Branched-Chain Amino Acids Activate Key Enzymes in Protein Synthesis after Physical Exercise1-3
Jan 01, 2006; ... ABSTRACT BCAAs (leucine, isoleucine, and valine), particularly leucine, have anabolic effects on protein metabolism by increasing the rate of protein synthesis and decreasing the rate of protein degradation in resting human muscle. Also, during recovery from endurance exercise, BCAAs ...
Amino Acids and Muscle Loss with Aging1-3
Jan 01, 2006; ... ABSTRACT Aging is associated with a progressive loss of muscle mass (sarcopenia), which increases the risks of injury and disability. Although the mechanisms of sarcopenia are not clearly elucidated, age-associated alterations in the muscle anabolic response to nutritional stimuli and a ...
Branched-Chain Amino Acids and Central Fatigue1-3
Jan 01, 2006; ... ABSTRACT An account of the tryptophan (Trp)-5-hydroxytryptamine (S-HT)-central fatigue theory is provided and an explanation of how oral administration of BCAAs can decrease fatigue on the basis of this theory is given. The rate-limiting step in the synthesis of 5-HT is the transport of ...
Application of Branched-Chain Amino Acids in Healthy Humans: Discussion of Session 3(1,2)
Jan 01, 2006; ... Dr. Kurpad was asked to put the branched-chain amino acid requirement for normal humans, of about 80 mg per kg body wt per d, in the context of population nutrition and the use of food supplements. Dr. Kurpad responded that it is very hard to get a diet that is limiting in branched-chain amino ...
Transamination of Leucine and Nitrogen Accretion in Human Pregnancy and the Newborn Infant1-3
Jan 01, 2006; ... ABSTRACT Kinetics of leucine and its oxidation were determined in human pregnancy and in the newborn infant, using stable isotopic tracers, to quantify the dynamic aspects of protein metabolism. These data show that in human pregnancy there is a decrease in whole-body rate of leucine ...
Branched-Chain Amino Acid Enriched Supplements as Therapy for Liver Disease1-3
Jan 01, 2006; ... ABSTRACT Altered amino acid metabolism is a hallmark of liver disease, characterized by low levels of circulating BCAAs and elevated levels of circulating aromatic amino acids, and methionine. Although overwhelming evidence indicates that the incidence of complications of liver disease ...
Branched-Chain Amino Acids and Immunity1,2
Jan 01, 2006; ... ABSTRACT Although there has been great interest in the effects of amino acids on immune function, little is known about the impact of changes in BCAA availability on the ability of the immune system to function. Human immune cells incorporate BCAA into proteins and are able to oxidize ...
Branched-Chain Amino Acid-Enriched Nutritional Support in Surgical and Cancer Patients1,2
Jan 01, 2006; ... ABSTRACT Prolonged surgical stress and advanced malignant disease lead to systemic catabolism characterized by depletion of muscle protein and oxidation of skeletal muscle BCAA. BCAA oxidation provides energy for muscle and other organs and is the precursor for amino acid synthesis to ...
Application of Branched-Chain Amino Acids in Human Pathological States: Renal Failure1,2
Jan 01, 2006; ... ABSTRACT During renal failure, abnormalities of BCAA and branched-chain keto acid (BCKA) metabolism are due to both the lack of renal contribution to amino acid metabolism and the impact of renal failure and acidosis on whole-body nitrogen metabolism. Abnormal BCAA and BCKA metabolism ...
Therapeutic Use of Branched-Chain Amino Acids in Burn, Trauma, and Sepsis1,2
Jan 01, 2006; ... ABSTRACT Various experimental studies conducted in the 1970s demonstrated, at least in the physiological situation, the anabolic and/or anticatabolic properties of branched-chain amino acids (leucine, valine, isoleucine) or their ketoacid derivatives. This led to several clinical studies ...
Symposium on Branched-Chain Amino Acids: Conference Summary1,2
Jan 01, 2006; ... BCAAs, especially leucine, were shown in the mid-1970s to be potent regulators of protein turnover (1-3). In the mid1980s BCAAs were also shown to compete with other large neutral amino acids (LNAAs)4 (4), suggesting that raising the blood concentration of BCAA would limit the formation of false ...
Assessment of Branched-Chain Amino Acid Status and Potential for Biomarkers1-3
Jan 01, 2006; ... ABSTRACT BCAAs are not synthesized in the body in humans, but they are crucial in protein and neurotransmitter synthesis. The protein anabolic role of BCAAs seems to be mediated not only by their important role as a promoter of the translation process (and possibly acting at the ...
Potential Importance of Leucine in Treatment of Obesity and the Metabolic Syndrome1-3
Jan 01, 2006; ... ABSTRACT Diets with total protein intake >1.5 g*kg^sup -1^*d^sup -1^ and carbohydrate intake <150 g/d are effective for treatment of obesity, type 2 diabetes, and the Metabolic Syndrome. These diets improve body composition and enhance glycemic control. During weight loss, ...
Application of Branched-Chain Amino Acids in Human Pathological States: Discussion of Session 4(1,2)
Jan 01, 2006; ... Dr. Fernstrom started the discussion by asking Dr. Charlton, with regard to the Marchesini study he discussed, if this new study included measures beyond the simple outcome measures followed in the earlier study? If so, did the new measures provide some indication of the underlying biochemical ...
Identification of the Regulatory Region of the L-Type Pyruvate Kinase Gene in Mouse Liver by Hydrodynamics-Based Gene Transfection1
Jan 01, 2006; ... ABSTRACT Expression of L-type pyruvate kinase (L-PK) is upregulated in the liver by dietary carbohydrate. Previously, 3 carbohydrate/insulin response elements were identified in the 5'-flanking region of the L-PK gene up to bp -170. Studies of the 5'-flanking region beyond bp -183 in ...
Helen Gertrude Oldham (1903-2004)
Jan 01, 2006; ... Helen Oldham was a scientist whose research contributed to the literature on nutritional requirements, a mentor who provided invaluable guidance to students, and an administrator who supported the work of nutritionists across the country. She retained an intellectual vigor and interest in ...
Rat Gastrointestinal Tissues Metabolize Quercetin1,2
Jan 01, 2006; ... ABSTRACT Quercetin and quercetin glycosides from food or dietary supplements appear in body tissues almost exclusively as glucuronated, sulfated, and methylated quercetin conjugates, suggesting that the in vivo bioactivity of quercetin may be due to its metabolites. In this study, pre- ...
Rapamycin Inhibits Liver Growth during Refeeding in Rats via Control of Ribosomal Protein Translation but Not Cap-Dependent Translation Initiation1
Jan 01, 2006; ... ABSTRACT We examined the role of the mammalian target of rapamycin (mTOR) in hepatic cell growth. To dissociate cell growth from cell proliferation, we employed an in vivo model of nonproliferative liver growth in rats, refeeding after 48 h of food deprivation. Starvation resulted in a ...
Increased Colonic Luminal Synthesis of Butyric Acid Is Associated with Lowered Colonic Cell Proliferation in Piglets1,2
Jan 01, 2006; ... ABSTRACT Butyrate inhibits colonic cell proliferation in vitro but reportedly has an opposite effect in vivo. Because lactulose feeding decreases cecal cell proliferation, an effect attenuated by prefeeding inulin, we hypothesized that lactulose feeding would decrease colonic luminal ...
Of the Major Phenolic Acids Formed during Human Microbial Fermentation of Tea, Citrus, and Soy Flavonoid Supplements, Only 3,4-Dihydroxyphenylacetic Acid Has Antiproliferative Activity1,2
Jan 01, 2006; ... ABSTRACT Dietary flavonoids are poorly absorbed from the gastrointestinal tract. Colonic bacteria convert flavonoids into smaller phenolic acids (PA), which can be absorbed into the circulation and may contribute to the chemopreventive activity of the parent compounds. The purpose of our ...
Soy Isoflavones Alter Expression of Genes Associated with Cancer Progression, Including Interleukin-8, in Androgen-Independent PC-3 Human Prostate Cancer Cells1
Jan 01, 2006; ... ABSTRACT High consumption of soy isoflavones in Asian diets has been correlated with a lower incidence of clinically important cases of prostate cancer. The chemopreventive properties of these diets may result from an interaction of several types of isoflavones, including genistein and ...
Beef Tallow Increases the Potency of Conjugated Linoleic Acid in the Reduction of Mouse Mammary Tumor Metastasis1,2
Jan 01, 2006; ... ABSTRACT Animal studies consistently show that dietary conjugated linoleic acid (CLA) reduces mammary tumorigenesis including metastasis. Relatively low concentrations of CLA are required for those effects, and a threshold level exists above which there is no added reduction. We reasoned ...
A Lignan Complex Isolated from Flaxseed Does Not Affect Plasma Lipid Concentrations or Antioxidant Capacity in Healthy Postmenopausal Women1,2
Jan 01, 2006; ... ABSTRACT A lignan complex rich in the plant lignan secoisolariciresinol diglucoside (SDG) was isolated from flaxseed. SDG is metabolized by the colonic microflora to the mammalian lignans enterodiol (END) and enterolactone (ENL), and was hypothesized to reduce plasma lipid concentrations ...
Consumption of Soy Isoflavones Does Not Affect Plasma Total Homocysteine or Asymmetric Dimethylarginine Concentrations in Healthy Postmenopausal Women1,2
Jan 01, 2006; ... ABSTRACT Postmenopausal women are at increased risk for cardiovascular disease because many risk factors are aggravated by menopause. Phytoestrogens may modulate risk factors favorably, involving mechanisms similar to estrogen. The effect of phytoestrogens on the atherogenic amino acids ...
Bread Fortified with Cholecalciferol Increases the Serum 25-Hydroxyvitamin D Concentration in Women as Effectively as a Cholecalciferol Supplement1
Jan 01, 2006; ... ABSTRACT Fortification of foods is a feasible way of preventing low vitamin D status. Bread could be a suitable vehicle for fortification because it is a common part of diets worldwide. The bioavailability of cholecalciferol from bread is not known. We studied cholecalciferol stability, ...
Branched-Chain Amino Acid Needs in Children with Mild-to-Moderate Chronic Cholestatic Liver Disease1,2
Jan 01, 2006; ... ABSTRACT Protein-energy malnutrition is prevalent in children with chronic cholestatic liver disease. Supplementation of branched-chain amino acids (BCAA) in infants and children with chronic liver disease has been associated with significant improvement in growth and nitrogen balance, ...
Early Programming of Body Composition and Fat Distribution in Adolescents1
Jan 01, 2006; ... ABSTRACT Size at birth and early postnatal growth are determinants of adult height and BMI. The aim of this study was to evaluate the effect of birth weight on body composition and fat distribution in a group of Spanish adolescents. Current body composition was assessed by both skinfold ...
Dietary Saturated Fat Intake Is Inversely Associated with Bone Density in Humans: Analysis of NHANES III1,2
Jan 01, 2006; ... ABSTRACT Mounting evidence indicates that the amount and type of fat in the diet can have important effects on bone health. Most of this evidence is derived from animal studies. Of the few human studies that have been conducted, relatively small numbers of subjects and/or primarily ...
Low Serum Selenium and Total Carotenoids Predict Mortality among Older Women Living in the Community: The Women's Health and Aging Studies1
Jan 01, 2006; ... ABSTRACT Selenium and the carotenoids play an important role in antioxidant defenses and in the redox regulation involved in inflammation. We tested the hypothesis that low selenium and carotenoids predict mortality in older women living in the community. Women who were enrolled in the ...
Nutritional Status Improves after Treatment of Schistosoma japonicum-Infected Children and Adolescents1
Jan 01, 2006; ... ABSTRACT Studies addressing the relation between chronic schistosomiasis japonica and nutritional status are limited. We conducted a longitudinal treatment-reinfection study in Leyte, the Philippines, among 477 Schistosoma japonicum-infected subjects aged 7-20 y, to evaluate changes in ...
PYY[3-36] Administration Decreases the Respiratory Quotient and Reduces Adiposity in Diet-Induced Obese Mice1
Jan 01, 2006; ... ABSTRACT In rodents, weight reduction after peptide YY[3-36] (PYY[3-36]) administration may be due largely to decreased food consumption. Effects on other processes affecting energy balance (energy expenditure, fuel partitioning, gut nutrient uptake) remain poorly understood. We examined ...
Induction of Hepatic Antioxidant Enzymes by Phenolic Acids in Rats Is Accompanied by Increased Levels of Multidrug Resistance-Associated Protein 3 mRNA Expression1
Jan 01, 2006; ... ABSTRACT Phenolic acids are widespread in plant foods; they contain important biological and pharmacological properties, some of which were shown to be effective in preventing cancer. We investigated the modulatory effects of phenolic acids on an antioxidant system in male Sprague-Dawley ...
Nutritional Studies in Victorian Prisons
Jan 01, 2006; ... It was controversy over the feeding of prisoners that forced the British Government by the middle of the 19th century to consider what was already known and what more could be ascertained concerning the nutritional requirements of humans. This appears to be the first time any government had felt ...
Orally Administered Betaine Has an Acute and Dose-Dependent Effect on Serum Betaine and Plasma Homocysteine Concentrations in Healthy Humans1
Jan 01, 2006; ... ABSTRACT Betaine, i.e., trimethylglycine, is linked to homocysteine metabolism. A 3-mo daily betaine supplementation decreased even normal plasma total homocysteine (tHcy) concentrations in humans. The pharmacokinetic characteristics and metabolism of betaine in humans have not been ...
Copper Transport Protein (Ctr1) Levels in Mice Are Tissue Specific and Dependent on Copper Status1
Jan 01, 2006; ... ABSTRACT Studies were conducted to determine distribution of the copper transporter, Ctr1, a transmembrane protein responsible for cellular copper uptake, in adult mice and in suckling mice nursed by either copper-adequate (Cu+) or copper-deficient (Cu-) dams. Western immunoblot ...
Factors Affecting the Bioavailability of Soy Isoflavones in Humans after Ingestion of Physiologically Relevant Levels from Different Soy Foods1
Jan 01, 2006; ... ABSTRACT The precise role that isoflavones play in the health-related effects of soy foods, and their potential for adverse effects are controversial. This may be due in part to a lack of basic knowledge regarding their bioavailability and metabolism, particularly as it relates to the ...
Colonic Fermentation May Play a Role in Lactose Intolerance in Humans1
Jan 01, 2006; ... ABSTRACT The results of our previous study suggested that in addition to the small intestinal lactase activity and transit time, colonic processing of lactose may play a role in lactose intolerance. We investigated whether colonic fermentation of lactose is correlated with lactose ...
Dietary Fructooligosaccharides Affect Intestinal Barrier Function in Healthy Men
Jan 01, 2006; ... ABSTRACT In contrast to most expectations, we showed previously that dietary fructooligosaccharides (FOS) stimulate intestinal colonization and translocation of invasive Salmonella enteritidis in rats. Even before infection, FOS increased the cytotoxicity of fecal water, mucin excretion, ...
Flaxseed Oil Increases the Plasma Concentrations of Cardioprotective (n-3) Fatty Acids in Humans1
Jan 01, 2006; ... ABSTRACT α-Linolenic acid (ALA) is a major dietary (n-3) fatty acid. ALA is converted to longer-chain (n-3) PUFA, such as eicosapentaenoic acid (EPA) and possibly docosahexaenoic acid (DHA). EPA and DHA are fish-based (n-3) fatty acids that have proven cardioprotective properties ....
Fish Oil Affects Blood Pressure and the Plasma Lipid Profile in Healthy Danish Infants1
Jan 01, 2006; ... ABSTRACT Animal and epidemiologic studies indicate that early nutrition has lasting effects on metabolism and cardiovascular disease risk. In adults, (n-3) long-chain PUFA (LCPUFA) from fish oils improve blood pressure, the lipid profile, and possibly cardiovascular disease mortality ....
Lycopene Supplementation Prevents Smoke-Induced Changes in p53, p53 Phosphorylation, Cell Proliferation, and Apoptosis in the Gastric Mucosa of Ferrets1
Jan 01, 2006; ... ABSTRACT Cigarette smoking increases the risk for gastric cancer. Higher intakes or blood levels of lycopene are associated with a decreased risk of gastric cancer. However, the biological mechanisms by which lycopene may protect against gastric carcinogenesis are poorly understood. We ...
Dietary Vitamin A Has Both Chronic and Acute Effects on Vitamin A Indices in Lactating Rats and Their Offspring1,2
Jan 01, 2006; ... ABSTRACT To further investigate the effect of dietary vitamin A (VA) intake on milk VA concentrations and pup VA status, female rats were fed 2 concentrations of VA [0 (n = 9) or 50 µmol/kg diet (n = 10)] during pregnancy and lactation. Plasma retinol concentrations were significantly ...
Dietary Inulin Intake and Age Can Affect Intestinal Absorption of Zinc and Copper in Rats
Jan 01, 2006; ... ABSTRACT Nondigestible inulin-type fructan intake can stimulate intestinal mineral absorption in both humans and animals. However, this stimulatory effect may depend on experimental conditions such as the duration of the experience, mineral levels in the diet, and the animal's ...
Excessive Weight Gain during Pregnancy Is Associated with Earlier Termination of Breast-Feeding among White Women1,2
Jan 01, 2006; ... ABSTRACT High prepregnant BMI is associated with reduced initiation and duration of breast-feeding (BF). To examine how gestational weight gain (GWG) might modify this association, over a 9-y period, we identified all women (n = 2783) who had attempted to breast-feed their newborns. From ...
Trends in Serum Folate, RBC Folate, and Circulating Total Homocysteine Concentrations in the United States: Analysis of Data from National Health and Nutrition Examination Surveys, 1988-1994, 1999-2000, and 2001-2002(1)
Jan 01, 2006; ... ABSTRACT Folate intakes increased dramatically after folic acid fortification. We investigated the changes in serum folate, RBC folate, and total homocysteine (tHcy) concentrations utilizing data from National Health and Nutrition Examination Surveys (NHANES) 1988-2002. NHANES 1988-2002 ...
Psychosocial Factors and Socioeconomic Indicators Are Associated with Household Food Insecurity among Pregnant Women1
Jan 01, 2006; ... ABSTRACT Household food insecurity has been associated with several negative health outcomes, yet little is known about the prevalence and correlates of household food insecurity during pregnancy. This study was conducted as part of the Pregnancy, Infection, and Nutrition prospective ...
Consumption of Coffee, but Not Black Tea, Is Associated with Decreased Risk of Premenopausal Breast Cancer
Jan 01, 2006; ... ABSTRACT Caffeine has been suggested as a possible risk factor for breast cancer, potentially through its effect of facilitating the development of benign breast disease. However, coffee and tea also contain polyphenols, which exhibit anticarcinogenic properties. A hospital-based, ...
Unmetabolized Folic Acid in Plasma Is Associated with Reduced Natural Killer Cell Cytotoxicity among Postmenopausal Women1
Jan 01, 2006; ... ABSTRACT Folic acid (FA) supplements and food fortification are used to prevent neural tube defects and to lower plasma homocysteine. Through exposure to food fortification and vitamin supplement use, large populations in the United States and elsewhere have an unprecedented high FA ...
In Vivo Urea Kinetic Studies in Conscious Mice1
Jan 01, 2006; ... ABSTRACT Stable isotope studies in conscious mice have been limited by the invasive catheterization procedures and relatively large sample size required. We developed minimally invasive catheterization protocols that together with the ability to analyze small samples have allowed for the ...