Creatine Synthesis Research Articles

Estimating urine volume from the urine creatinine concentration.

Spot determinations of the urine creatinine concentration are widely used as a substitute for 24-h urine collections. Expressed as the amount excreted per gram of creatinine, urine concentrations in a single-voided sample are often used to estimate 24-h excretion rates of protein, sodium, potassium, calcium, magnesium, urea and uric acid. These estimates are predicated on the assumption that daily creatinine excretion equals 1 g (and that a urine creatinine concentration of 100mg/dL reflects a 1 L 24-h urine volume). Such estimates are invalid if the serum creatinine concentration is rising or falling. In addition, because creatinine excretion is determined by muscle mass, the assumption that 24-h urine creatinine excretion equals 1 g yields a misleading estimate at the extremes of age and body size. In this review, we evaluate seven equations for the accuracy of their estimates of urine volume based on urine creatinine concentrations in actual and idealized patients. None of the equations works well in patients who are morbidly obese or in patients with markedly decreased muscle mass. In other patients, estimates based on a reformulation of the Cockroft-Gault equation are reasonably accurate. A recent study based on this relationship found a high strength of correlation between estimated and measured urine output with chronic kidney disease (CKD) studied in the African American Study of Kidney Disease (AASK) trial and for the patients studied in the CKD Optimal Management with Binders and NictomidE (COMBINE) trial. However, the equation systematically underestimated urine output in the AASK trial. Hence, an intercept was added to account for the bias in the estimated output. A more rigorous equation derived from an ambulatory Swiss population, which includes body mass index and models the non-linear accelerated decline in creatinine excretion with age, could potentially be more accurate in overweight and elderly patients. In addition to extremes of body weight and muscle mass, decreased dietary intake or reduced hepatic synthesis of creatine, a precursor of creatinine or ingestion of creatine supplements will also result in inaccurate estimates. These limitations must be appreciated to rationally use predictive equations to estimate urine volume. If the baseline urine creatinine concentration is determined in a sample of known volume, subsequent urine creatinine concentrations will reveal actual urine output as well as the change in urine output. Given the constraints of the various estimating equations, a single baseline timed collection may be a more useful strategy for monitoring urine volume than entering anthropomorphic data into a calculator.

510 Late-Breaking: Dietary Glycine Supplementation During Growing and Finishing Phases Increases Tissue Concentrations of Total Creatine and Gene Expression of Creatine-synthetic Enzymes in Low-birthweight Pigs

Abstract Dietary glycine is required for maximum growth and development in animals by stimulating muscle protein synthesis and as a component of creatine. Creatine is synthesized from glycine, arginine, and S-adenosylmethionine by arginine:glycine amidinotransferase (AGAT) and guanidinoacetate N-methyltransferase (GAMT). Sufficient creatine synthesis for growth requires adequate substrate supply. However, swine diets are deficient in glycine. Additionally, intrauterine growth restricted (IUGR) pigs have reduced glycine synthesis. This results in decreased creatine synthesis and lower total creatine content in tissues, leading to reduced cellular energy metabolism and diminished muscle protein accretion. This study was designed to test the hypothesis that dietary glycine supplementation in corn-and-soybean-meal-based diets would improve overall growth and skeletal muscle accretion in post-weaning IUGR pigs by increasing the expression of creatine-synthetic enzymes and tissue concentrations of total creatine. Fourteen IUGR pigs (birthweight = 0.98±0.03 kg, mean±SEM) and 20 normal birthweight pigs (birthweight = 1.44±0.02 kg, mean±SEM) were obtained at weaning for this study. Pigs from each birthweight group were randomly assigned to 1% glycine + 0.19% corn starch treatment group or 1.19% alanine group (isonitrogenous control) for the study (21 d to 188 d of age); tissues were collected at d 188. Data were analyzed by using 2-way ANOVA and the Duncan multiple comparison test. Glycine-supplemented IUGR pigs had greater tissue concentrations of creatine, creatinine, and creatine phosphate than control IUGR in all tissues measured (P< 0.05). Control IUGR pigs showed diminished activity and mRNA expression of creatine-synthetic enzymes (P < 0.05); this was mitigated by glycine supplementation as glycine supplemented IUGR pigs showed normal levels of enzyme activity and mRNA expression. Overall, results of this study indicate dietary glycine supplementation to IUGR pigs between weaning and market weight effectively restores creatine-synthetic enzyme activities and increase tissue concentrations of total creatine, leading to increased lean tissue growth. (Supported by USDA-NIFA)

Creatine metabolism in patients with urea cycle disorders

The urea cycle generates arginine that is one of the major precursors for creatine biosynthesis. Here we evaluate levels of creatine and guanidinoacetate (the precursor in the synthesis of creatine) in plasma samples (ns = 207) of patients (np = 73) with different types of urea cycle disorders (ornithine transcarbamylase deficiency (ns = 22; np = 7), citrullinemia type 1 (ns = 60; np = 22), argininosuccinic aciduria (ns = 81; np = 31), arginase deficiency (ns = 44; np = 13)). The concentration of plasma guanidinoacetate positively correlated (p < 0.001, R2 = 0.64) with levels of arginine, but not with glycine in all patients with urea cycle defects, rising to levels above normal in most samples (34 out of 44) of patients with arginase deficiency. In contrast to patients with guanidinoacetate methyltransferase deficiency (a disorder of creatine synthesis characterized by elevated guanidinoacetate concentrations), creatine levels were normal (32 out of 44) or above normal (12 out of 44) in samples from patients with arginase deficiency. Creatine levels correlated significantly, but poorly (p < 0.01, R2 = 0.1) with guanidinoacetate levels and, despite being overall in the normal range in patients with all other urea cycle disorders, were occasionally below normal in some patients with argininosuccinic acid synthase and lyase deficiency. Creatine levels positively correlated with levels of methionine (p < 0.001, R2 = 0.16), the donor of the methyl group for creatine synthesis. The direct correlation of arginine levels with guanidinoacetate in patients with urea cycle disorders explains the increased concentration of guanidino compounds in arginase deficiency. Low creatine levels in some patients with other urea cycle defects might be explained by low protein intake (creatine is naturally present in meat) and relative or absolute intracellular arginine deficiency.

Prospective identification by neonatal screening of patients with guanidinoacetate methyltransferase deficiency

IntroductionGuanidinoacetate methyltransferase (GAMT) deficiency is an inherited metabolic disorder that impairs the synthesis of creatine (CRE). Lack of CRE in the brain can cause intellectual disability, autistic-like behavior, seizures, and movement disorders. Identification at birth and immediate therapy can prevent intellectual disability and seizures. Here we report the first two cases of GAMT deficiency identified at birth by newborn screening (NBS) in Utah and New York. MethodsNBS dried blood spots were analyzed by tandem mass spectrometry (MS/MS) using either derivatized or non-derivatized assays to detect guanidinoacetate (GUAC) and CRE. For any positive samples, a second-tier test using a more selective method, ultra-performance liquid chromatography (UPLC) combined with MS/MS, was performed to separate GUAC from potential isobaric interferences. ResultsNBS for GAMT deficiency began in Utah on June 1, 2015 using a derivatized method for the detection of GUAC and CRE. In May 2019, the laboratory and method transitioned to a non-derivatized method. GAMT screening was added to the New York State NBS panel on October 1, 2018 using a derivatized method. In New York, a total of 537,408 babies were screened, 23 infants were referred and one newborn was identified with GAMT deficiency. In Utah, a total of 273,902 infants were screened (195,425 with the derivatized method, 78,477 with the non-derivatized method), three infants referred and one was identified with GAMT deficiency. Mean levels of GUAC and CRE were similar between methods (Utah derivatized: GUAC = 1.20 ± 0.43 μmol/L, CRE = 238 ± 96 μmol/L; Utah non-derivatized: GUAC = 1.23 ± 0.61 μmol/L, CRE = 344 ± 150 μmol/L, New York derivatized: GUAC = 1.34 ± 0.57 μmol/L, CRE = 569 ± 155 μmol/L). With either Utah method, similar concentrations of GUAC are observed in first (collected around 1 day of age) and the second NBS specimens (routinely collected at 7–16 days of age), while CRE concentrations decreased in the second NBS specimens. Both infants identified with GAMT deficiency started therapy by 2 weeks of age and are growing and developing normally at 7 (Utah) and 4 (New York) months of age. ConclusionsNewborn screening allows for the prospective identification of GAMT deficiency utilizing elevated GUAC concentration as a marker. First-tier screening may be incorporated into existing methods for amino acids and acylcarnitines without the need for new equipment or staff. Newborn screening performed by either derivatized or non-derivatized methods and coupled with second-tier testing, has a very low false positive rate and can prospectively identify affected children.SummaryCerebral creatine deficiency syndromes caused by defects in creatine synthesis can result in intellectual disability, and are preventable if therapy is initiated early in life. This manuscript reports the identification of two infants with GAMT deficiency (one of the cerebral creatine deficiency syndromes) by newborn screening and demonstrates NBS feasibility using a variety of methods.

Creatine promotes cancer metastasis through activation of Smad2/3

As one of the most popular nutrient supplements, creatine has been highly used to increase muscle mass and improve exercise performance. Here, we report an adverse effect of creatine using orthotopic mouse models, showing that creatine promotes colorectal and breast cancer metastasis and shortens mouse survival. We show that glycine amidinotransferase (GATM), the rate-limiting enzyme for creatine synthesis, is upregulated in liver metastases. Dietary uptake, or GATM-mediated de novo synthesis of creatine, enhances cancer metastasis and shortens mouse survival by upregulation of Snail and Slug expression via monopolar spindle 1 (MPS1)-activated Smad2 and Smad3 phosphorylation. GATM knockdown or MPS1 inhibition suppresses cancer metastasis and benefits mouse survival by downregulating Snail and Slug. Our findings call for using caution when considering dietary creatine to improve muscle mass or treat diseases and suggest that targeting GATM or MPS1 prevents cancer metastasis, especially metastasis of transforming growth factor beta receptor mutant colorectal cancers.

Value of Magnetic Resonance Spectroscopy for Diagnosis of Creatine Deficiency Syndrome

AbstractCreatine deficiency syndromes are congenital metabolic diseases characterized by decreased cerebral creatine levels as a result of disorders in creatine synthesis and transport. Therefore, magnetic resonance spectroscopy is a valuable tool for diagnosis. This disease can be explained by congenital disorders occurring in three forms at different stages of the creatine metabolic pathway. Two of disorders arise autosomal recessively in creatine biosynthesis, arginine-glycine amidinotransferase, and guanidinoacetate methyltransferase enzyme deficiency. The third disorder occurs as a result of an SLC6A8 variant in the form of creatine carrier protein deficiency. In this article, a patient with SLC6A8 carrier deficiency is presented.

Neonatal Piglets Can Synthesize Adequate Creatine, but Only with Sufficient Dietary Arginine and Methionine, or with Guanidinoacetate and Excess Methionine

BackgroundSuckling piglets synthesize most of their creatine requirement, which consumes substantial amounts of arginine in order to synthesize guanidinoacetic acid (GAA) and methionine in order to transmethylate GAA to creatine. ObjectivesTo determine whether supplemental GAA or creatine spare arginine and/or methionine for protein synthesis and, if GAA is supplemented, whether excess methionine is needed for conversion to creatine. MethodsYucatan miniature piglets (9–11 days old; both sexes) were fed 1 of 5 elemental diets for 5 days: 1) low arginine (0.3 g·kg−1·d−1) and low methionine (0.20 g·kg−1·d−1; Base); 2) Base plus GAA (0.093 g·kg−1·d−1; +GAA); 3) Base plus GAA plus excess methionine (0.5 g·kg−1·d−1; +GAA/Met); 4) Base plus creatine (0.12 g·kg−1·d−1; +Cre); or 5) excess arginine (1.8 g·kg−1·d−1) and excess methionine (+Arg/Met). Isotope tracers were infused to determine whole-body GAA, creatine, and protein synthesis; tissues were analyzed for creatine synthesis enzymes and metabolite concentrations. Data were analyzed by 1-way ANOVA. Results: GAA and creatine syntheses were 115% and 32% higher, respectively, with the +Arg/Met diet (P < 0.0001), in spite of 33% lower renal L-arginine: glycine amidinotransferase activity (P < 0.0001) compared to Base, suggesting substrate availability dictates synthesis rather than enzyme capacity. GAA or creatine supplementation reduced arginine conversion to creatine by 46% and 43%, respectively (P < 0.01), but did not spare amino acids for whole-body protein synthesis, suggesting that limited amino acids were diverted to protein at the expense of creatine synthesis. The +GAA/Met diet led to higher creatine concentrations in the kidney (2.6-fold) and liver (7.6-fold) than the +GAA diet (P < 0.01), suggesting excess methionine is needed for GAA conversion to creatine. ConclusionsPiglets are capable of synthesizing sufficient creatine from the precursor amino acids arginine and methionine, or from GAA plus methionine.

How does obesity promote breast cancer tumor growth?

Obesity is a risk factor for many cancers. Maguire etal. (2021) found increased creatine synthesis by the adipocytes adjacent to breast cancers in obese mice. The creatine is transported into the cancer cells, producing larger tumors, possibly due to greater energy availability.

86583 The role of creatine in developmental myelination and remyelination

ABSTRACT IMPACT: This study highlights the importance of creatine in developmental myelination and remyelination to investigate whether creatine provides a therapeutic value during a central nervous system (CNS) demyelinating insult with a potential value in patients with Multiple Sclerosis. OBJECTIVES/GOALS: Creatine is vital for ATP buffering in the brain. Interestingly, the cells that generate myelin express the main enzyme for creatine synthesis, Gamt. Patients with Gamt mutations display intellectual delays and impaired myelination. Therefore, we hypothesize that creatine is essential for developmental myelination and improves remyelination. METHODS/STUDY POPULATION: To investigate these hypotheses, we developed a new transgenic mouse model with LoxP sites flanking exons 2-6 of the guanidinoacetate methyltransferase (Gamt) gene where excision leads to expression of a green fluorescent tag allowing us to track the cells normally expressing Gamt. We used immunohistochemistry techniques to look at the corpus callosum, the main white matter tract in the brain, and evaluate the number of oligodendrocytes (OL), glial cells responsible for generating myelin. We also used the cuprizone model of toxic demyelination to investigate whether dietary creatine and cyclocreatine, a planar analog of creatine that more efficiently crosses the blood-brain barrier, can enhance remyelination. RESULTS/ANTICIPATED RESULTS: In this mouse model, we show a 95% (+/-0.47%, n=3) co-localization of Gamt within mature OL during postnatal (P) day P14 with no co-localization in neurons or other glial cells. This suggests that mature OL are the main cells making creatine in the CNS. Next, we show that knocking out Gamt leads to a significant reduction in OL in the developing corpus callosum, at P14 and P21 (P14: 0.007, n=3; P21: 0.04, n=3). We also show that creatine supplementation causes a trending increase in mature OL density in the corpus callosum following cuprizone demyelination (2% creatine; p=0.052; n=4). Interestingly, cyclocreatine supplementation significantly increased mature OL density in the corpus callosum following cuprizone demyelination (0.1% cyclocreatine; p=0.034; n=4). DISCUSSION/SIGNIFICANCE OF FINDINGS: These studies highlight the important role creatine plays in developmental myelination and remyelination to investigate whether creatine and cyclocreatine provide a therapeutic value during a CNS demyelinating insult. This work investigates a potential therapeutic value of creatine to patients with Multiple Sclerosis.

Creatine Supplementation and Brain Health.

There is a robust and compelling body of evidence supporting the ergogenic and therapeutic role of creatine supplementation in muscle. Beyond these well-described effects and mechanisms, there is literature to suggest that creatine may also be beneficial to brain health (e.g., cognitive processing, brain function, and recovery from trauma). This is a growing field of research, and the purpose of this short review is to provide an update on the effects of creatine supplementation on brain health in humans. There is a potential for creatine supplementation to improve cognitive processing, especially in conditions characterized by brain creatine deficits, which could be induced by acute stressors (e.g., exercise, sleep deprivation) or chronic, pathologic conditions (e.g., creatine synthesis enzyme deficiencies, mild traumatic brain injury, aging, Alzheimer’s disease, depression). Despite this, the optimal creatine protocol able to increase brain creatine levels is still to be determined. Similarly, supplementation studies concomitantly assessing brain creatine and cognitive function are needed. Collectively, data available are promising and future research in the area is warranted.

Role of L-Arginine in Nitric Oxide Synthesis and Health in Humans.

As a functional amino acid (AA), L-arginine (Arg) serves not only as a building block of protein but also as an essential substrate for the synthesis of nitric oxide (NO), creatine, polyamines, homoarginine, and agmatine in mammals (including humans). NO (a major vasodilator) increases blood flow to tissues. Arg and its metabolites play important roles in metabolism and physiology. Arg is required to maintain the urea cycle in the active state to detoxify ammonia. This AA also activates cellular mechanistic target of rapamycin (MTOR) and focal adhesion kinase cell signaling pathways in mammals, thereby stimulating protein synthesis, inhibiting autophagy and proteolysis, enhancing cell migration and wound healing, promoting spermatogenesis and sperm quality, improving conceptus survival and growth, and augmenting the production of milk proteins. Although Arg is formed de novo from glutamine/glutamate and proline in humans, these synthetic pathways do not provide sufficient Arg in infants or adults. Thus, humans and other animals do have dietary needs of Arg for optimal growth, development, lactation, and fertility. Much evidence shows that oral administration of Arg within the physiological range can confer health benefits to both men and women by increasing NO synthesis and thus blood flow in tissues (e.g., skeletal muscle and the corpora cavernosa of the penis). NO is a vasodilator, a neurotransmitter, a regulator of nutrient metabolism, and a killer of bacteria, fungi, parasites, and viruses [including coronaviruses, such as SARS-CoV and SARS-CoV-2 (the virus causing COVID-19). Thus, Arg supplementation can enhance immunity, anti-infectious, and anti-oxidative responses, fertility, wound healing, ammonia detoxification, nutrient digestion and absorption, lean tissue mass, and brown adipose tissue development; ameliorate metabolic syndromes (including dyslipidemia, obesity, diabetes, and hypertension); and treat individuals with erectile dysfunction, sickle cell disease, muscular dystrophy, and pre-eclampsia.

Tactics of managing a cardiac patient with comorbidity: promising opportunities for correction of endothelial dysfunction

Background. Arterial hypertension (AH) and heart diseases are the leading causes of morbidity, mortality and the number of visits to the doctor. Cardiac patients are characterized by the frequent polymorbidity. The cardiovascular continuum, which predicts the course of events from atherosclerosis to the final stages of cardiovascular diseases (CVD), includes the following pathogenetic links: oxidative stress, inflammation and endothelial dysfunction (ED).&#x0D; Objective. To describe the management of a cardiac patient with comorbidity and promising options for the ED correction.&#x0D; Materials and methods. Analysis of the literature on this issue.&#x0D; Results and discussion. The previous paradigm of CVD development involved damage to target organs due to hypertension. Instead, according to the current paradigm, CVD are the result of the vascular dysfunction. The recently proposed paradigm indicates that all CVD are based on ED. Nitric oxide (NO) is the main molecule necessary for the proper functioning of the endothelium. NO takes part in the relaxation of blood vessels and smooth muscles, regulates the synthesis and secretion of a number of hormones, controls platelet activity and the interaction of leukocytes with vascular walls, participates in antipathogenic reactions of the immune system. ED is known to be a predictor of complications and poorer survival in patients with coronary heart disease. Dysfunctional endothelium promotes vasoconstriction, oxidation, inflammation and thrombosis. To improve the condition of the endothelium, it is advisable to increase the NO content. The increase in NO content can be the result of angiotensin-converting enzyme inhibitors, calcium channel blockers, sartans, statins, estrogens, antioxidants, and aspirin intake, as well as exercise. L-arginine is the substrate for the NO formation in human body. Potential mechanisms of L-arginine effect in AH include improvement of endothelial function, increase of vascular NO synthesis, decrease of endothelin-1 and angiotensin II activity, modulation of renal hemodynamics and reduction of oxidative stress. L-arginine therapy (9 g per day for 4 weeks) reduced systolic blood pressure by 4 mm Hg and diastolic – by 2.6 mm Hg. L-arginine also has a beneficial effect on the metabolic profile via increasing insulin sensitivity. The use of L-arginine is well studied in patients with chronic heart failure (HF) with preserved ejection fraction. In this category of patients, such treatment leads to an increase in glomerular filtration rate, improvement of endothelium-dependent vasodilation, reduction of the functional class of HF. The ESPEN guidelines on parenteral nutrition state that the use of L-arginine has both NO-dependent and NO-independent effects. The latter include the synthesis of creatine, proline and polyamines; stimulation of insulin and growth hormone secretion. Administration of L-arginine in combination with L-carnitine helps to eliminate the advanced glycation end products and to increase the rate of glomerular filtration.&#x0D; Conclusions. 1. The cardiovascular continuum includes such elements as oxidative stress, inflammation and endothelial dysfunction. 2. NO is the main molecule necessary for the proper functioning of the endothelium. 3. L-arginine is the substrate for the NO formation in human body. L-arginine also helps to improve endothelial function, to reduce the activity of endothelin-1 and angiotensin II, to modulate renal hemodynamics and to reduce oxidative stress. 4. L-arginine also has a beneficial effect on the metabolic profile via increasing insulin sensitivity. 5. In patients with chronic HF with preserved ejection fraction, treatment with L-arginine leads to an increase in glomerular filtration rate, improvement of endothelium-dependent vasodilation, reduction of the functional class of HF.

Urine creatine metabolite panel as a screening test in neurodevelopmental disorders

BackgroundCerebral creatine deficiency disorders (CCDD) are inherited metabolic disorders of creatine synthesis and transport. Urine creatine metabolite panel is helpful to identify these disorders.MethodsWe reviewed electronic patient charts for all patients that underwent urine creatine metabolite panel testing in the metabolic laboratory at our institution.ResultsThere were 498 tests conducted on 413 patients. Clinical, molecular genetics and neuroimaging features were available in 318 patients. Two new patients were diagnosed with creatine transporter deficiency: one female and one male, both had markedly elevated urine creatine. Urine creatine metabolite panel was also used as a monitoring test in our metabolic laboratory. Diagnostic yield of urine creatine metabolite panel was 0.67% (2/297). There were six known patients with creatine transporter deficiency. The prevalence of creatine transporter deficiency was 2.64% in our study in patients with neurodevelopmental disorders who underwent screening or monitoring of CCDS at our institution.ConclusionEven though the diagnostic yield of urine creatine metabolite panel is low, it can successfully detect CCDD patients, despite many neurodevelopmental disorders are not a result of CCDD. To the best of our knowledge, this study is the first Canadian study to report diagnostic yield of urine creatine metabolite panel for CCDD from a single center.

103 Equine enterocytes actively oxidize L-glutamine but do not synthesize L-citrulline and L-arginine from L-glutamine or L-proline in vitro

Abstract In many mammals, enterocytes are responsible for the synthesis of L-citrulline and L-arginine from L-glutamine and L-proline. However, there is limited research in the horse to determine de novo synthesis of L-citrulline or L-arginine by the enterocyte, which is the initial step in establishing dietary requirements and comprehending arginine nutrition in horses. We utilized jejunal enterocytes from 20 horses (neonate n = 2, mature n = 16, and geriatric n = 2) to study glutamine and proline metabolism. As a positive control, enterocytes were isolated from 0, 60, and 180-day old pigs (n = 8/age group). Equine or porcine enterocytes were incubated at 37oC for 30 min in oxygenated (95% O2/5% CO2) Krebs bicarbonate buffer (pH 7.4) containing 5 mM D-glucose and either 2 mM L-[U-14C]glutamine or 2 mM L-[U-14C]proline plus 2 mM L-glutamine. Collected 14CO2 was determined by a liquid scintillation counter, whereas amino acids in cells plus medium were analyzed by HPLC. Both equine and porcine enterocytes oxidized glutamine to CO2 but had a limited ability to oxidize proline to CO2, confirming the biochemical viability of the cells in vitro. Enterocytes from neonatal and geriatric horses had lower rates (nmol/106 cells/30 min) of CO2 production (1.10 ± 0.52 and 1.31 ± 0.65, respectively) from glutamine than those (40.9 ± 5.40) from mature horses. Porcine enterocytes synthesized L-citrulline and L-arginine from glutamine and proline (e.g., 4.86 ± 0.26 nmol L-citrulline/mg protein/30 min and 0.85 ± 0.04 nmol L-arginine/mg protein/30 min from glutamine in enterocytes of 60-day-old pigs). In contrast, equine enterocytes did not synthesize L-citrulline and L-arginine from L-glutamine or L-proline. Because L-arginine is an essential substrate for the synthesis of protein, nitric oxide, and creatine, our novel findings on the lack of intestinal synthesis of L-arginine in horses have important implications for their nutrition, metabolism, and health.

208 Effects of supplemental guanidinoacetic acid, creatine, and choline on protein deposition and methyl group metabolites in growing steers

Abstract Methyl group donors (e.g., methionine, choline) can improve performance in transition dairy cows. Our objective was to determine how modulation of methyl group status would affect protein deposition and plasma and urine metabolites associated with methyl group metabolism. Six ruminally cannulated Holstein steers (200 kg) were used in a 6×6 Latin square design with 10-d periods. Factorial treatments, which were continuously infused abomasally, included 3 methyl group modulators (MGM: control; 15 g/d guanidinoacetic acid [GAA]; or 16.8 g/d creatine) and 2 levels of choline (0 or 5 g/d choline ion). Providing GAA or creatine increases body creatine supply; however, GAA consumes methyl groups to synthesize creatine, whereas supplemental creatine directly spares methyl groups that would be used for its synthesis. Steers received 4 kg/d of a corn-based diet. Total collection of urine and feces occurred from d 7 to 9 to measure N retention. Jugular blood was collected on d 10. No interactions between MGM and choline were observed. GAA increased N retention (P = 0.04), whereas creatine did not. Urinary creatine excretion was increased by GAA and creatine supplementation (P &amp;lt; 0.0001). Urinary GAA output was greater for GAA than creatine and control (P &amp;lt; 0.0001). Plasma creatine concentration was increased by GAA and creatine supplementation (P ≤0.01), with GAA leading to a larger increase. Plasma GAA concentration increased with GAA provision (P &amp;lt; 0.0001) but tended to be decreased by creatine (P = 0.09). Plasma urea-N and urinary urea-N output were not affected by MGM (P ≥ 0.25). Choline did not affect N retention (P = 0.69) or urinary GAA or creatine excretions (P ≥ 0.14). Choline increased plasma creatine (P = 0.04), but not plasma GAA. Choline did not affect plasma urea-N or urinary urea-N output (P ≥ 0.68). These data demonstrate that GAA has potential to improve protein deposition in growing cattle. Additionally, choline provision may allow for greater creatine synthesis in the body.

When to measure plasma homocysteine and how to place it in context: The homocystinurias.

This review presents clinical patterns that should trigger homocysteine measurement in blood, as well as the further diagnostic work-up focused on inborn errors of metabolism and disorders of vitamin B12 (cobalamin) absorption and supply. The numerous conditions (e.g. cardiovascular disease, Alzheimer’s disease) for which mild-to-moderate hyperhomocysteinaemia caused by genetic polymorphisms or acquired reasons is considered a risk factor are beyond the scope of this review.Homocysteine is a sulphur-containing amino acid, which is derived from the amino acid methionine. Homocysteine is either trans-sulphurated to form cystathionine and then cysteine, or re-methylated to methionine. The trans-sulphuration reaction depends on the enzyme cystathionine beta synthase and its cofactor vitamin B6. The re-methylation reaction not only involves the enzymes methionine synthase and methionine synthase reductase but also depends on the cofactor cobalamin and on the provision of methyl groups from the folate cycle. Because the homocysteine–methionine cycle provides for the vast majority of methyl groups in the body, it is central to numerous pathways that depend on methyl group supply, such as creatine synthesis or DNA methylation. Based on this premise, the severity of clinical presentations of inborn errors of metabolism, such as classical homocystinuria or the cobalamin C (cblC) defect, affecting this pathway is unsurprising.

Maternal Supplementation with Dietary Betaine during Gestation to Improve Twin Lamb Survival.

Simple SummaryHigh incidences of twin lamb mortality constrain the reproductive efficiency and productivity of Merino sheep flocks. This study determined whether supplementing the diets of pregnant, twin-bearing ewes with 2 or 4 g/day of betaine would improve lamb viability and survival to weaning. Feeding ewes 2 g/day of betaine for the duration of pregnancy decreased lamb survival but increased lamb body weight at weaning. Whereas, lamb vigour and early post-natal survival were improved following ewe supplementation with 4 g/day of betaine during the second half of pregnancy. Maternal supplementation with 4 g/day of betaine during the second half of pregnancy may, therefore, be a useful strategy to improve twin lamb survival.Betaine increases the synthesis of creatine, an energy-rich amino acid that increases adenosine triphosphate (ATP) and has neuroprotective properties which may improve post-natal lamb survival. This study determined whether maternal betaine supplementation during gestation would improve body weight, thermoregulation, time to stand and suck, colostrum intake and survival to weaning of twin lambs. Twin-bearing Merino ewes received dietary betaine at either 0 g/day (Control, CTL), 2 g/day from ram introduction to parturition (Early betaine, EB) or 4 g/day from Day 80 of gestation to parturition (Late betaine, LB). Ewes were housed individually during parturition and measures were collected at 4, 24 and 72 h and Day 7 post-partum, and at marking (53.2 ± 0.2 days of age) and weaning (99.3 ± 0.2 days of age). The EB treatment resulted in heavier lambs at weaning compared with CTL and LB lambs (p < 0.05). Time to stand and suck from birth was longer in EB lambs (p < 0.05), whereas, the interval from birth to first suck was shorter for LB lambs (p < 0.05). Lamb survival rate was the highest for LB lambs at 72 h and Day 7 (p < 0.05), and lowest for EB lambs on Day 7 (p < 0.05). These data indicated that betaine supplementation at 4 g/day during the second half of pregnancy improved twin lamb survival to Day 7 and shortened the interval from birth to first suck; whereas feeding ewes 2 g/day of betaine for the duration of pregnancy increased twin lamb body weight at weaning, but increased both the time to attain behavioural milestones and mortalities before Day 7.

Creatine metabolism in the uterus: potential implications for reproductive biology

Creatine is an amino acid derivative synthesized from arginine, glycine and methionine. It serves as the substrate for the creatine kinase system, which is vital for maintaining ATP levels in tissues with high and fluctuating energy demand. There exists evidence that the creatine kinase system operates in both the endometrial and myometrial layers of the uterus. While use and regulation of this system in the uterus are not well understood, it is likely to be important given uterine tissues undergo phases of increased energy demand during certain stages of the female reproductive cycle, pregnancy, and parturition. This review discusses known adaptations of creatine metabolism in the uterus during the reproductive cycle (both estrous and menstrual), pregnancy and parturition, highlighting possible links to fertility and the existing knowledge gaps. Specifically, we discuss the adaptations and regulation of uterine creatine metabolite levels, cell creatine transport, de novo creatine synthesis, and creatine kinase expression in the various layers and cell types of the uterus. Finally, we discuss the effects of dietary creatine on uterine metabolism. In summary, there is growing evidence that creatine metabolism is up-regulated in uterine tissues during phases where energy demand is increased. While it remains unclear how important these adaptations are in the maintenance of healthy uterine function, furthering our understanding of uterine creatine metabolism may uncover strategies to combat poor embryo implantation and failure to conceive, as well as enhancing uterine contractile performance during labor.

The Effects of Creatine and Related Compounds on Cardiovascular System: From Basic to Applied Studies

Abstract Beneficial effects of creatine were firstly shown in sport, where itself has been recognized as an ergogenic substance, increasing exercise endurancе, muscle strength and lean body mass. Creatine supplementation is very interesting, due to the fact that creatine supplementation have been reported to be beneficial for wide spectrum of diseases and conditions referring neuro-degenerative, rheumatic diseases, myopathies, cancer, type 2 diabetes. Creatine is a principle component of the creatine kinase/phosphagen system. In cardiomyocytes, it plays an important role in the buffering and transport of chemical energy to ensure that supply meets the dynamic demands of the heart. Studies in mice proved that elevated creatine protects the heart from ischemia-reperfusion injury. A natural precursor of creatine, guanidinoacetic acid (GAA), plays an important role as an energy carrier/mediator in the cell. GAA is formed in the first step of creatine synthesis. Supplementation with GAA might be of great significance in some circumstances where biosynthesis of GAA is limited like deficient diet, kidney failure, renal insufficiency, exercise-related GAA depletion. Betaine is a neutral compound in the form of zwitterion. Betaine supplementation is associated with improved cognition, neuroprotection, cardioprotection and exercise physiology. Betaine insufficiency represents increased risk for secondary heart failure and acute myocardial infarction. This mini-review outlines the evidence in support of creatine and creatine related compounds (GAA and betaine) elevation and examines the pharmacological approaches that are currently available. Since data from the available studies, regarding cardioprotection are inconsistent, this review might help clarifying the benefits of creatine, GAA and betaine supplementation on cardiovascular system.

Preconditioning beef cattle for long-duration transportation stress with rumen-protected methionine supplementation: A nutrigenetics study.

In general, beef cattle long-distance transportation from cow-calf operations to feedlots or from feedlots to abattoirs is a common situation in the beef industry. The aim of this study was to determine the effect of rumen-protected methionine (RPM) supplementation on a proposed gene network for muscle fatigue, creatine synthesis (CKM), and reactive oxygen species (ROS) metabolism after a transportation simulation in a test track. Angus × Simmental heifers (n = 18) were stratified by body weight (408 ± 64 kg; BW) and randomly assigned to dietary treatments: 1) control diet (CTRL) or 2) control diet + 8 gr/hd/day of top-dressed rumen-protected methionine (RPM). After an adaptation period to Calan gates, animals received the mentioned dietary treatment consisting of Bermuda hay ad libitum and a soy hulls and corn gluten feed based supplement. After 45 days of supplementation, animals were loaded onto a trailer and transported for 22 hours (long-term transportation). Longissimus muscle biopsies, BW and blood samples were obtained on day 0 (Baseline), 43 (Pre-transport; PRET), and 46 (Post-transport; POST). Heifers’ average daily gain did not differ between baseline and PRET. Control heifer’s shrink was 10% of BW while RPM heifers shrink was 8%. Serum cortisol decreased, and glucose and creatine kinase levels increased after transportation, but no differences were observed between treatments. Messenger RNA was extracted from skeletal muscle tissue and gene expression analysis was performed by RT-qPCR. Results showed that AHCY and DNMT3A (DNA methylation), SSPN (Sarcoglycan complex), and SOD2 (Oxidative Stress-ROS) were upregulated in CTRL between baseline and PRET and, decreased between pre and POST while they remained constant for RPM. Furthermore, CKM was not affected by treatments. In conclusion, RPM supplementation may affect ROS production and enhance DNA hypermethylation, after a long-term transportation.