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Nathan Goodyear

The Role of Post-Exercise Nutrient Administration on Muscle Protein Synthesis and Glyco... - 0 views

  • Whey protein was superior to that of casein in upregulating protein synthesis
  • ability to digest more rapidly than casein protein
  • Free form amino acid ingestion acts similarly to whey by displaying a rapid and strong increase in aminoacidemia
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  • it appears that protein synthesis rapidly increases for up to two hours after amino acid administration
  • The intervention of dietary protein or amino acid supplementation in conjunction with resistance training has proven to effectively increase protein synthesis rates
  • 291% increase in protein synthesis following the exercise bout, while protein degradation remained unchanged from baseline quantities
  • it has been established that post-exercise EAA supplementation stimulates protein synthesis, in conjunction with a positive protein balance, comparable to that of intravenous infusion of amino acids
  • Casein and whey protein ingestion yielded similar values of net positive protein balance, and thus an overall increase in protein synthesis
  • A later analysis revealed that soy protein increased protein synthesis in rats similar to that of whey after a treadmill exercise protocol
  • A human trial, however, concluded that milk proteins (caseins and whey) in comparison to soy promoted greater muscle protein accretion when they were ingested after regular resistance training
  • Whey hydrolysate ingested after a resistance exercise bout acutely stimulated mixed muscle protein synthesis 31% greater than soy
  • adequate amount of protein (20 g) is ingested (Tipton et al., 2009) immediately before or after a resistance exercise bout
  • The rapid phase lasts approximately 30-60 minutes and does not require the presence of insulin
  • slow phase, which can last up to several hours if carbohydrate availability is high and insulin levels remain elevated
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    Good review of recovery supplement strategy.
Nathan Goodyear

Branched Chain Amino Acid Supplementation for Patients with Cirrhosis | Clinical Correl... - 0 views

  • low level of BCAAs in patients with cirrhosis is hypothesized to be one of multiple factors responsible for development of hepatic encephalopathy
  • supplementation of BCAAs is thought to facilitate ammonia detoxification by supporting synthesis of glutamine, one of the non-branched chain amino acids, in skeletal muscle and in the brain as well as diminishing the influx of AAAs across the blood-brain barrier
  • oral BCAA supplementation is more useful in chronic encephalopathic patients than is parenteral BCAA supplementation in patients with acute encephalopathy
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  • malnutrition progressing to cachexia is another common manifestation of cirrhosis
  • Malnutrition can be mitigated with BCAA supplementation
  • Studies show that administration of amino acid formulas enriched with BCAAs can reduce protein loss, support protein synthesis, and improve nutritional status of patients with chronic liver disease
  • Leucine has been shown to be the most effective of the BCAAs because it acts via multiple pathways to stimulate protein synthesis
  • BCAAs metabolites inhibit proteolysis
  • Patients with cirrhosis have both insulin deficiency and insulin resistance
  • BCAAs (particularly leucine) help to reverse the catabolic, hyperglucagonemic state of cirrhosis both by stimulating insulin release from the pancreatic β cells and by decreasing insulin resistance allowing for better glucose utilization
  • Coadministration of BCAAs and glucose has been found to be particularly useful
  • BCAA supplementation improves protein-energy malnutrition by improving utilization of glucose, thereby diminishing the drive for proteolysis, inhibiting protein breakdown, and stimulating protein synthesis
  • Cirrhotic patients have impaired immune defense, characterized by defective phagocytic activity and impaired intracellular killing activity
  • another effect of BCAA supplementation is improvement of phagocytic function of neutrophils and possibly improvement in natural killer T (NKT) cell lymphocyte activity
  • BCAA supplementation may reduce the risk of infection in patients with advanced cirrhosis not only through improvement in protein-energy malnutrition but also by directly improving the function of the immune cells themselves
  • BCAA administration has also been shown to have a positive effect on liver regeneration
  • A proposed mechanism for improved liver regeneration is the stimulatory effect of BCAAs (particularly leucine) on the secretion of hepatocyte growth factor by hepatic stellate cells
  • BCAAs activate rapamycin signaling pathways which promotes albumin synthesis in the liver as well as protein and glycogen synthesis in muscle tissue
  • Chemical improvement with BCAA treatment is demonstrated by recovery of serum albumin and lowering of serum bilirubin levels
  • long-term oral BCAA supplementation was useful in staving off malnutrition and improving survival by preventing end-stage fatal complications of cirrhosis such as hepatic failure and gastrointestinal bleeding
  • The incidence of death by any cause, development of liver cancer, rupture of esophageal varices, or progression to hepatic failure was decreased in the group that received BCAA supplementation
  • Patients receiving BCAA supplementation also have a lower average hospital admission rate, better nutritional status, and better liver function tests
  • patients taking BCAA supplementation report improved quality of life
  • BCAAs have been shown to mitigate hepatic encephalopathy, cachexia, and infection rates, complications associated with the progression of hepatic cirrhosis
  • BCAAs make up 20-25% of the protein content of most foods
  • Highest levels are found in casein whey protein of dairy products and vegetables, such as corn and mushrooms. Other sources include egg albumin, beans, peanuts and brown rice bran
  • In addition to BCAAs from diet, oral supplements of BCAAs can be used
  • Oral supplementation tends to provide a better hepatic supply of BCAAs for patients able to tolerate PO nutrition as compared with IV supplementation, especially when treating symptoms of hepatic encephalopathy
  • Coadministration of BCAAs with carnitine and zinc has also been shown to increase ammonia metabolism further reducing the encephalopathic symptoms
  • Cirrhotic patients benefit from eating frequent, small meals that prevent long fasts which place the patient in a catabolic state
  • the best time for BCAA supplementation is at bedtime to improve the catabolic state during starvation in early morning fasting
  • A late night nutritional snack reduces symptoms of weakness and fatigability, lowers postprandial hyperglycemia, increases skeletal muscle mass,[25] improves nitrogen balance, and increases serum albumin levels.[26] Nocturnal BCAAs even improve serum albumin in cirrhotic patients who show no improvement with daytime BCAAs
  • Protein-energy malnutrition (PEM), with low serum albumin and low muscle mass, occurs in 65-90% of cases of advanced cirrhosis
  • hyperglucagonemia results in a catabolic state eventually producing anorexia and cachexia
  • BCAAs are further depleted from the circulation due to increased uptake by skeletal muscles that use the BCAAs in the synthesis of glutamine, which is produced in order to clear the ammonia that is not cleared by the failing liver
  • patients with chronic liver disease, particularly cirrhosis, routinely have decreased BCAAs and increased aromatic amino acids (AAAs) in their circulation
  • Maintaining a higher serum albumin in patients with cirrhosis is associated with decreased mortality and improved quality of life
  • the serum BCAA concentration is strongly correlated with the serum albumin level
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    great review of cirrhosis and BCCA supplementation.
Nathan Goodyear

Androgen deprivation promotes intratumoral synthesis of dihydrotestosterone from androg... - 0 views

  • PSA levels in media were increased by 3α-diol
  • Similarly to 3α-diol, 3β-diol also increased PSA levels in media in a concentration-dependent manner
  • intracellular DHT is synthesized from inactive androgen 3α- and 3β-diol via different pathways in prostate cancer cells
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    • Nathan Goodyear
       
      error in statement: DHT metabolites are not inactive, they just don't activate AR.
  • 3β-diol can be a precursor of DHT in prostate cancer cells.
  • serum 3α-diol G levels reflect the androgen milieu in localized prostate cancer patients receiving ADT
  • A few studies reported that 3β-diol is a potential ligand of estrogen receptor β (ERβ) and has an antiproliferative effect
  • our results revealed that 3β-diol is potentially a precursor of DHT in prostate cancer cells
  • Bauman et al. showed that 3α-diol is inactive at AR, but induces prostate growth
  • Prostate cancer cells promoted synthesis from the DHT metabolite 3α-diol during the long duration of ADT
    • Nathan Goodyear
       
      the authors highlight the suggestion is that 3alpha-diol's activity is via 3alpha-HSD, but fail to mention that it is known that 3alpha-diol interacts with the ER-alpha in the prostate.
  • verified the synthesis of DHT from 3α- or 3β-diol via different pathways in prostate cancer cells in this study
  • HSD17B6 expression levels in prostate cancer can be useful for the diagnosis of high-risk prostate cancer
  • serum 3α-diol G levels reflect the adrenal androgen milieu in localized prostate cancer patients
  • 3α- and 3β-diol has a much more significant role in intratumoral androgen metabolism during ADT
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    DHT metabolites play an important role of intra-prostate DHT synthesis in those following ADT.  This is a proposed mechanism for the failure rate and aggressive nature of prostate cancer that fails ADT.   3-alpha androstanediol is converted via 3 alpha HSD back to DHT.  In contrast, 3-beta androstanediol cannot.
Nathan Goodyear

The role of short-chain fatty acids in the interplay between diet, gut microbiota, and ... - 0 views

  • Acetate, propionate, and butyrate are present in an approximate molar ratio of 60:20:20 in the colon and stool
  • SCFAs might play a key role in the prevention and treatment of the metabolic syndrome, bowel disorders, and certain types of cancer
  • SCFA administration positively influenced the treatment of ulcerative colitis, Crohn's disease, and antibiotic-associated diarrhea
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  • Gut bacteria in the cecum and large intestine produce SCFAs mainly from nondigestible carbohydrates that pass the small intestine unaffected
  • plant cell-wall polysaccharides, oligosaccharides, and resistant starches
  • inulin shifted the relative production of SCFAs from acetate to propionate and butyrate
  • age of approximately 3–4 years, when it becomes mature
  • SCFAs affect lipid, glucose, and cholesterol metabolism
  • colonocytes, the first host cells that take up SCFAs and which depend largely on butyrate for their energy supply
  • the microbiota educate the immune system and increase the tolerance to microbial immunodeterminants
  • the microbiota act as a metabolic organ that can break down otherwise indigestible food components, degrade potentially toxic food compounds like oxalate, and synthesize certain vitamins and amino acids
  • a large part of the SCFAs is used as a source of energy
  • The general idea is that colonocytes prefer butyrate to acetate and propionate, and oxidize it to ketone bodies and CO2
  • Exogenous acetate formed by colonic bacterial fermentation enters the blood compartment and is mixed with endogenous acetate released by tissues and organs (103, 104). Up to 70% of the acetate is taken up by the liver (105), where it is not only used as an energy source, but is also used as a substrate for the synthesis of cholesterol and long-chain fatty acids and as a cosubstrate for glutamine and glutamate synthesis
  • SCFAs regulate the balance between fatty acid synthesis, fatty acid oxidation, and lipolysis in the body.
  • Fatty acid oxidation is activated by SCFAs, while de novo synthesis and lipolysis are inhibited
  • obese animals in this study showed a 50% reduction in relative abundance of the Bacteroidetes (i.e., acetate and propionate producers), whereas the Firmicutes (i.e., butyrate producers) were proportionally increased compared with the lean counterparts.
  • increase in total fecal SCFA concentrations in obese humans.
  • In humans the distinct relation between the Firmicutes:Bacteroidetes ratio and obesity is less clear.
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    Great review of the role of SCFA in gut health and body metabolism
Nathan Goodyear

Leucine-enriched essential amino acid supplementation during moderate steady state exer... - 0 views

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    leucine shown to increase muscle protein synthesis post exercise
Nathan Goodyear

Intratumoral androgen biosynthesis in prostate cancer pathogenesis and response to therapy - 0 views

  • Additional studies have similarly found that prostate tissue levels of DHT in PCa patients treated with ADT therapy before prostatectomy declined by only ∼75% versus declines of ∼95% in serum levels
  • In a recent study in healthy men, treatment for 1 month with a GnRH antagonist to suppress testicular androgen synthesis caused a 94% decline in serum testosterone, but only a 70–80% decline in prostate tissue testosterone and DHT
  • progression to CRPC was associated with increased intratumoral accumulation or synthesis of testosterone.
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  • the intraprostatic synthesis of testosterone from adrenal-derived precursors likely accounts for the relatively high testosterone levels in prostate after ADT
  • In addition, AR activity in these cells is likely further enhanced by multiple mechanisms that sensitize AR to low levels of androgens
  • higher affinity ligand DHT (approximately eightfold higher affinity
  • type 2 5α-reductase (SRD5A2) being the major enzyme in prostate
  • reduce DHT to 5α-androstane-3α,17β-diol (3α-androstanediol; Ji et al. 2003, Rizner et al. 2003), which is then glucuronidated to form 3α-androstanediol glucuronide by the enzymes UDP glycosyltransferase 2, B15 (UGT2B15) or UGT2B17
  • DHT in prostate is inactivated by the enzyme AKR1C2, which is also termed 3α-hydroxysteroid dehydrogenase type 3 (3α-HSD type 3
    • Nathan Goodyear
       
      The metabolite 3-alpha androstanediol is NOT inactive as this author states.  This DHT metabolite actually can stimulate  ER alpha receptors in the prostate.
  • AKR1C1, is also expressed in prostate. However, in contrast to AKR1C2, it converts DHT primarily to 5α-androstane-3β,17β-diol (3β-androstanediol; Steckelbroeck et al. 2004), which is a potential endogenous ligand for the estrogen receptor β
  • Significantly, intraprostatic testosterone levels were not substantially reduced relative to controls with normal serum androgen levels, although DHT levels were reduced to 18% of controls
  • testosterone levels in many of the CRPC samples were actually increased relative to control tissues (Montgomery et al. 2008). While DHT levels were less markedly increased, this may have reflected DHT catabolism
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    This article discusses the failure of androgen deprivation therapy and prostate cancer.  This failure is quite common.  The authors point to alpha-DHT as the primary mechanism through AR stimulation.  However, we know that DHT metabolites also stimulate estrogen receptors.
Nathan Goodyear

Membrane Estrogen Receptors Stimulate Intracellular Calcium Release and Progesterone Sy... - 0 views

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    Estradiol stimulates hypothalamic progesterone synthesis in astrocytes in rat model.  This occurs through activation of calcium channels and influx of calcium.  ER alpha appears to be the prominent ER involved.
Nathan Goodyear

Nutrition & Metabolism | Full text | Fructose, insulin resistance, and metabolic dyslip... - 0 views

  • For thousands of years humans consumed fructose amounting to 16–20 grams per day
  • daily consumptions amounting to 85–100 grams of fructose per day
  • Of key importance is the ability of fructose to by-pass the main regulatory step of glycolysis, the conversion of glucose-6-phosphate to fructose 1,6-bisphosphate, controlled by phosphofructokinase
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  • Thus, while glucose metabolism is negatively regulated by phosphofructokinase, fructose can continuously enter the glycolytic pathway. Therefore, fructose can uncontrollably produce glucose, glycogen, lactate, and pyruvate, providing both the glycerol and acyl portions of acyl-glycerol molecules. These particular substrates, and the resultant excess energy flux due to unregulated fructose metabolism, will promote the over-production of TG (reviewed in [53]).
  • Glycemic excursions and insulin responses were reduced by 66% and 65%, respectively, in the fructose-consuming subjects
  • reduction in circulating leptin both in the short and long-term as well as a 30% reduction in ghrelin (an orexigenic gastroenteric hormone) in the fructose group compared to the glucose group.
  • A prolonged elevation of TG was also seen in the high fructose subjects
  • Both fat and fructose consumption usually results in low leptin concentrations which, in turn, leads to overeating in populations consuming energy from these particular macronutrients
  • Chronic fructose consumption reduces adiponectin responses, contributing to insulin resistance
  • A definite relationship has also been found between metabolic syndrome and hyperhomocysteinemia
  • the liver takes up dietary fructose rapidly where it can be converted to glycerol-3-phosphate. This substrate favours esterification of unbound FFA to form the TG
  • Fructose stimulates TG production, but impairs removal, creating the known dyslipidemic profile
  • the effects of fructose in promoting TG synthesis are independent of insulinemia
  • Although fructose does not appear to acutely increase insulin levels, chronic exposure seems to indirectly cause hyperinsulinemia and obesity through other mechanisms. One proposed mechanism involves GLUT5
  • If FFA are not removed from tissues, as occurs in fructose fed insulin resistant models, there is an increased energy and FFA flux that leads to the increased secretion of TG
  • In these scenarios, where there is excess hepatic fatty acid uptake, synthesis and secretion, 'input' of fats in the liver exceed 'outputs', and hepatic steatosis occurs
  • Carbohydrate induced hypertriglycerolemia results from a combination of both TG overproduction, and inadequate TG clearance
  • fructose-induced metabolic dyslipidemia is usually accompanied by whole body insulin resistance [100] and reduced hepatic insulin sensitivity
  • Excess VLDL secretion has been shown to deliver increased fatty acids and TG to muscle and other tissues, further inducing insulin resistance
  • the metabolic effects of fructose occur through rapid utilization in the liver due to the bypassing of the regulatory phosphofructokinase step in glycolysis. This in turn causes activation of pyruvate dehydrogenase, and subsequent modifications favoring esterification of fatty acids, again leading to increased VLDL secretion
  • High fructose diets can have a hypertriglyceridemic and pro-oxidant effect
  • Oxidative stress has often been implicated in the pathology of insulin resistance induced by fructose feeding
  • Administration of alpha-lipoic acid (LA) has been shown to prevent these changes, and improve insulin sensitivity
  • LA treatment also prevents several deleterious effects of fructose feeding: the increases in cholesterol, TG, activity of lipogenic enzymes, and VLDL secretion
  • Fructose has also been implicated in reducing PPARα levels
  • PPARα is a ligand activated nuclear hormone receptor that is responsible for inducing mitochondrial and peroxisomal β-oxidation
  • decreased PPARα expression can result in reduced oxidation, leading to cellular lipid accumulation
  • fructose diets altered the structure and function of VLDL particles causing and increase in the TG: protein ratio
  • LDL particle size has been found to be inversely related to TG concentration
  • therefore the higher TG results in a smaller, denser, more atherogenic LDL particle, which contributes to the morbidity of the metabolic disorders associated with insulin resistance
  • High fructose, which stimulates VLDL secretion, may initiate the cycle that results in metabolic syndrome long before type 2 diabetes and obesity develop
  • A high flux of fructose to the liver, the main organ capable of metabolizing this simple carbohydrate, disturbs normal hepatic carbohydrate metabolism leading to two major consequences (Figure 2): perturbations in glucose metabolism and glucose uptake pathways, and a significantly enhanced rate of de novo lipogenesis and TG synthesis, driven by the high flux of glycerol and acyl portions of TG molecules coming from fructose catabolism
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    Fructose and metabolic syndrome.  Good discussion of the impact of high fructose intake and metabolic dysfunction.  This study also does a great job of highlighting the historical change of fructose intake.
Nathan Goodyear

A high proportion of leucine is required for optimal stimulation of the rate of muscle ... - 0 views

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    amino acid leucine promotes muscle protein synthesis
Nathan Goodyear

Leucine Regulates Translation Initiation of Protein Synthesis in Skeletal Muscle after ... - 0 views

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    Leucine, a branch chain amino acid, important in promoting protein synthesis and thus muscle growth.  Very important post-exercise and in athletes
Nathan Goodyear

Biologic and Pharmacologic Principles of ET for Menopause: Estrogen Steroidogenesis and... - 0 views

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    biologic and pharmacologic principles of ET for Menopause: Estrogen synthesis and action
Nathan Goodyear

PLOS ONE: Alcohol Ingestion Impairs Maximal Post-Exercise Rates of Myofibrillar Protein... - 0 views

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    makes sense.  Alcohol impairs recovery from exercise--specifically protein synthesis.
Nathan Goodyear

Effects of testosterone replacement on muscle mass and muscle protein synthesis in hypo... - 0 views

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    Testosterone therapy in men with low T is associated with an increase in protein synthesis and thus an increase in muscle mass.
Nathan Goodyear

Effect of testosterone on muscle mass and muscle protein synthesis | Journal of Applied... - 0 views

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    Testosterone promotes muscle mass increase through increased protein synthesis.
Nathan Goodyear

Testosterone administration to elderly men increases skeletal muscle strength and prote... - 0 views

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    small study finds that Testosterone therapy in elderly men increased protein synthesis, muscle mass, and increase in strength.
Nathan Goodyear

Changes in Thymidine Kinase and α-Amylase Activity during Isoproterenol-stimu... - 0 views

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    salivary TK-1 increased in response to stimulated increased DNA synthesis in mouse model.
Nathan Goodyear

Nutrients | Free Full-Text | Myths, Artifacts, and Fatal Flaws: Identifying Limitations... - 0 views

  • l-gulonolactone oxidase, an enzyme with the synthesis of l-ascorbic acid as its only known function
  • prolonged fasting causes ascorbate synthesis to decline
  • agents that stimulate glycogenolysis also stimulate ascorbate synthesis when an animal is in a fed state
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    Great review on the science of vitamin C.
Nathan Goodyear

Effect of oral administration of testosterone on brachial arterial vasoreactivity in me... - 0 views

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    physiologic replacement of testosterone shown to increase NO synthesis, increased vasorelaxation, and reduced CVD symptoms, like hypertension.
Nathan Goodyear

Inflammatory Mechanisms in Obesity - Annual Review of Immunology, 29(1):415 - 0 views

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    good review of inflammation-obesity link.  THis article also discusses endoplasmic reticulum stress associated with inflammation and obesity.  The result is decoupling of protein synthesis.  This article also discusses some anti-inflammatory therapies.  This link is for abstract only.  Full article is not available on line.  
Nathan Goodyear

Nutritional regulation of muscle protein synthesis with resistance exercise: strategies... - 0 views

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    This study proposes that immediate post-resistance training protein helps to stimulate muscle growth. Recovery from training is just as important as the training itself.
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