Carnosine: can understanding its actions on energy metabolism and protein homeostasis inform its therapeutic potential?

Dihydropyrimidinase deficiency with atrioventricular septal defect: a case report

OBJECTIVES

Dihydropyrimidinase deficiency is a rare autosomal recessive disorder of the pyrimidine degradation pathway, with fewer than 40 patients published. Clinical findings are variable and some patients may remain asymptomatic. Global developmental delay and increased susceptibility to 5-fluorouracil are commonly reported. Here we present atrioventricular septal defect as a novel feature in dihydropyrimidinase deficiency.

CASE PRESENTATION

A four-year-old male with global developmental delay, dysmorphic facies, autistic features and a history of seizures was diagnosed with dihydropyrimidinase deficiency based on strikingly elevated urinary dihydrouracil and dihydrothymine and a homozygous pathogenic nonsense variant in DPYS gene. He had a history of complete atrioventricular septal defect corrected surgically in infancy.

CONCLUSIONS

This is the second report of congenital heart disease in dihydropyrimidinase deficiency, following a single patient with a ventricular septal defect. The rarity of the disease and the variability of the reported findings make it difficult to describe a disease-specific clinical phenotype. The mechanism of neurological and other systemic findings is unclear. Dihydropyrimidinase deficiency should be considered in patients with microcephaly, developmental delay, epilepsy and autistic traits. We suggest that congenital heart disease may also be a rare phenotypic feature.

Effect of carnosine synthesis precursors in the diet on jejunal metabolomic profiling and biochemical compounds in slow-growing Korat chicken

The slow-growing Korat chicken (KR) has been developed to provide an alternative breed for smallholder farmers in Thailand. Carnosine enrichment in the meat can distinguish KR from other chicken breeds. Therefore, our aim was to investigate the effect of enriched carnosine synthesis, obtained by the β-alanine and L-histidine precursor supplementation in the diet, on changes to metabolomic profiles and biochemical compounds in slow-growing KR jejunum tissue. Four hundred 21-day-old female KR chickens were divided into 4 experimental groups: a group with a basal diet, a group with a basal diet supplemented with 1.0% β-alanine, 0.5% L-histidine, and a mix of 1.0% β-alanine and 0.5% L-histidine. The feeding trial lasted 70 d. Ten randomly selected chickens from each group were slaughtered. Metabolic profiles were analyzed using proton nuclear magnetic resonance spectroscopy. In total, 28 metabolites were identified. Significant changes in the concentrations of these metabolites were detected between the groups. Partial least squares discriminant analysis was used to distinguish the metabolites between the experimental groups. Based on the discovered metabolites, 34 potential metabolic pathways showed differentiation between groups, and 8 pathways (with impact values higher than 0.05, P < 0.05, and FDR < 0.05) were affected by metabolite content. In addition, biochemical changes were monitored using synchrotron radiation-based Fourier transform infrared microspectroscopy. Supplementation of β-alanine alone in the diet increased the β-sheets and decreased the α-helix content in the amide I region, and supplementation of L-histidine alone in the diet also increased the β-sheets. Furthermore, the relationship between metabolite contents and biochemical compounds were confirmed using principal component analysis (PCA). Results from the PCA indicated that β-alanine and L-histidine precursor group was highly positively correlated with amide I, amide II, creatine, tyrosine, valine, isoleucine, and aspartate. These findings can help to understand the relationships and patterns between the spectral and metabolic processes related to carnosine synthesis.

A Comparative Biochemical Study Between L-Carnosine and β-Alanine in Amelioration of Hypobaric Hypoxia-Induced Skeletal Muscle Protein Loss

Rathor, Richa, Sukanya Srivastava, and Geetha Suryakumar. A comparative biochemical study between L-carnosine and β-alanine in amelioration of hypobaric hypoxia-induced skeletal muscle protein loss. High Alt Med Biol. 24:302-311, 2023. Background: Carnosine (CAR; β-alanyl-L-histidine), a biologically active dipeptide is known for its unique pH-buffering capacity, metal chelating activity, and antioxidant and antiglycation property. β-Alanine (ALA) is a nonessential amino acid and used to enhance performance and cognitive functions. Hypobaric hypoxia (HH)-induced muscle protein loss is regulated by multifaceted signaling pathways. The present study investigated the beneficial effects of CAR and ALA against HH-associated muscle loss. Methodology: Simulated HH exposure was performed in an animal decompression chamber. Gastric oral administration of CAR (50 mg·kg-1) and ALA (450 mg·kg-1) were given daily for 3 days and at the end of the treatment, hindlimb skeletal muscle tissue was excised for western blot and biochemical assays. Results: Cosupplementation of CAR and ALA alone was able to ameliorate the hypoxia-induced inflammation, oxidative stress (FOXO), ER stress (GRP-78), and atrophic signaling (MuRF-1) in the skeletal muscles. Creatinine phospho kinase activity and apoptosis were also decreased in CAR- and ALA-supplemented rats. However, CAR showed enhanced protection in HH-induced muscle loss as CAR supplementation was able to enhance protein concentration, body weight, and decreased the protein oxidation and ALA administration was not able to restore the same. Conclusions: Hence, the present comprehensive study supports the fact that CAR (50 mg·kg-1) is more beneficial as compared with ALA (450 mg·kg-1) in ameliorating the hypoxia-induced skeletal muscle loss.

Protein aggregation and glycation in Escherichia coli exposed to desiccation-rehydration stress

In natural environments, bacteria often enter a state of anhydrobiosis due to water loss. Multiple studies have demonstrated that desiccation may lead to protein aggregation and glycation both in vivo and in vitro. However, the exact effects of water-loss-induced proteotoxic stress and the interplay between protein glycation and aggregation in bacteria remain elusive. Our studies revealed that protein aggregates formation in Escherichia coli started during desiccation and continued during the rehydration stage. The aggregates were enriched in proteins prone to liquid-liquid phase separation. Although it is known that glycation may induce protein aggregation in vitro, the aggregates formed in E. coli contained low levels of glycation products compared to the soluble protein fraction. Carnosine, glycine betaine and trehalose diminished the formation of protein aggregates and glycation products, resulting in increased E. coli viability. Notably, although high concentrations of glycine-betaine and trehalose significantly enhanced protein aggregation, glycation was still inhibited and E. coli cells survived desiccation better than bacteria grown without osmolytes. Taken together, our results suggest that the aggregates might play protective functions during early desiccation-rehydration stress. Moreover, it seems glycation rather than protein aggregation is the main cause of E. coli death upon desiccation-rehydration stress.

The Therapeutic Mechanism of Schisandrol A and Its Metabolites on Pulmonary Fibrosis Based on Plasma Metabonomics and Network Analysis

Background

Schisandrol A (Sch A) is the main active ingredient of Schisandra chinensis (Turcz.) Baill. Our previous study showed that Sch A has anti-pulmonary fibrosis (PF) activity, but its metabolic-related mechanisms of action are not clear.

Methods

Here, we explored the therapeutic mechanisms of Sch A on PF by ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) metabolomics approach and network analysis. The metabolites of Sch A in mice (bleomycin + Sch A high-dose group) plasma were identified based on ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS).

Results

32 metabolites were detected reversed to normal level after treating bleomycin (BLM)-induced PF mice with Sch A. The 32 biomarkers were enriched in energy metabolism and several amino acid metabolisms, which was the first report on the therapeutic effects of Sch A on PF through rescuing the disordered energy metabolism. The UPLC-Q-TOF/MS analysis identified 17 possible metabolites (including isomers) of Sch A in mice plasma. Network analysis revealed that Sch A and 17 metabolites were related to 269 genes, and 1109 disease genes were related to PF. The construction of the Sch A/metabolites-target-PF network identified a total of 79 intersection genes and the TGF-β signaling pathway was determined to be the main signaling pathway related to the treatment of PF by Sch A. The integrated approach involving metabolomics and network analysis revealed that the TGF-β1-ID3-creatine pathway, TGF-β1-VIM-carnosine pathway were two of the possible pathways Sch A regulated to modulate metabolic disorders, especially energy metabolism, and the metabolite of Sch A M5 was identified as a most likely active metabolite.

Conclusion

The results suggested the feasibility of combining metabolomics and network analysis to reflect the effects of Sch A on the biological network and the metabolic state of PF and to evaluate the drug efficacy of Sch A and its related mechanisms.

Combinations of Vitamin A and Vitamin E Metabolites Confer Resilience against Amyloid-β Aggregation

Alzheimer's disease is characterized by the presence in the brain of amyloid plaques formed by the aberrant deposition of the amyloid-β peptide (Aβ). Since many vitamins are dysregulated in this disease, we explored whether these molecules contribute to the protein homeostasis system by modulating Aβ aggregation. By screening 18 fat-soluble and water-soluble vitamin metabolites, we found that retinoic acid and α-tocopherol, two metabolites of vitamin A and vitamin E, respectively, affect Aβ aggregation both in vitro and in a Caenorhabditis elegans model of Aβ toxicity. We then show that the effects of these two vitamin metabolites in specific combinations cancel each other out, consistent with the "resilience in complexity" hypothesis, according to which the complex composition of the cellular environment could have an overall protective role against protein aggregation through the simultaneous presence of aggregation promoters and inhibitors. Taken together, these results indicate that vitamins can be added to the list of components of the protein homeostasis system that regulate protein aggregation.

Effects of β-alanine and L-histidine supplementation on carnosine contents in and quality and secondary structure of proteins in slow-growing Korat chicken meat

Carnosine enrichment of slow-growing Korat chicken (KRC) meat helps differentiate KRC from mainstream chicken. We aimed to investigate the effects of β-alanine and L-histidine supplementation on the carnosine synthesis in and quality and secondary structure of proteins in slow-growing KRC meat. Four hundred 21-day-old female KRC were used, and a completely randomized design was applied. The chickens were divided into 4 experimental groups: basal diet (A), basal diet supplemented with 1.0% β-alanine (B), 0.5% L-histidine (C), and 1.0% β-alanine combined with 0.5% L-histidine (D). Each group consisted of 5 replicates (20 chickens per replicate). On d 70, 2 chickens per replicate were slaughtered, and the levels of carnosine, anserine, and thiobarbituric acid reactive substances were analyzed. Biochemical changes were monitored using synchrotron radiation-based Fourier transform infrared microspectroscopy; 5 chickens per replicate were slaughtered, and the meat quality was analyzed. Statistical analysis was performed using ANOVA and principal component analysis (PCA). Group D chickens exhibited the highest carnosine meat content, followed by those in groups B and C. However, amino acid supplementation did not affect anserine content and growth performance. Higher carnosine levels correlated with increasing pH_{45 min} and decreasing drip loss, cooking loss, shear force, and lipid oxidation. PCA revealed that supplementation with only β-alanine or L-histidine was related to increased content of β-sheets, β-turns, and aliphatic bending groups and decreased content of α-helix groups. This study is the first to report such findings in slow-growing chicken. Our findings suggest that KRC can synthesize the highest carnosine levels after both β-alanine and L-histidine supplementation. Higher carnosine contents do not adversely affect meat quality, improve meat texture, and alter the secondary structures of proteins. The molecular mechanism underlying carnosine synthesis in chickens needs further study to better understand and reveal markers that facilitate the development of nutrient selection programs.

Two human metabolites rescue a C. elegans model of Alzheimer's disease via a cytosolic unfolded protein response

Age-related changes in cellular metabolism can affect brain homeostasis, creating conditions that are permissive to the onset and progression of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Although the roles of metabolites have been extensively studied with regard to cellular signaling pathways, their effects on protein aggregation remain relatively unexplored. By computationally analysing the Human Metabolome Database, we identified two endogenous metabolites, carnosine and kynurenic acid, that inhibit the aggregation of the amyloid beta peptide (Aβ) and rescue a C. elegans model of Alzheimer's disease. We found that these metabolites act by triggering a cytosolic unfolded protein response through the transcription factor HSF-1 and downstream chaperones HSP40/J-proteins DNJ-12 and DNJ-19. These results help rationalise previous observations regarding the possible anti-ageing benefits of these metabolites by providing a mechanism for their action. Taken together, our findings provide a link between metabolite homeostasis and protein homeostasis, which could inspire preventative interventions against neurodegenerative disorders.

Use of carnosine in the prevention of cardiometabolic risk factors in overweight and obese individuals: study protocol for a randomised, double-blind placebo-controlled trial

INTRODUCTION

Carnosine, an over the counter food supplement, has been shown to improve glucose metabolism as well as cardiovascular risk factors in animal and human studies through its anti-inflammatory, antioxidative, antiglycating and chelating properties. The aim of this study is to establish if carnosine supplementation improves obesity, insulin sensitivity, insulin secretion, cardiovascular risk factors including arterial stiffness and endothelial function, and other risk factors related to diabetes and cardiovascular disease in the overweight and obese population.

METHODS AND ANALYSIS

Fifty participants will be recruited to be enrolled in a double-blind randomised controlled trial. Eligible participants with a body mass index (BMI) between 25 and 40 kg/m² will be randomly assigned to the intervention or placebo group. Following a medical review and oral glucose tolerance test to check eligibility, participants will then undergo testing. At baseline, participants will have anthropometric measurements (BMI, dual X-ray absorptiometry and peripheral quantitative CT scan), measurements of glucose metabolism (oral glucose tolerance test, intravenous glucose tolerance test and euglycaemic hyperinsulinaemic clamp), cardiovascular measurements (central blood pressure, endothelial function and arterial stiffness), a muscle and fat biopsy, physical activity measurement, liver fibroscan, cognitive function and questionnaires to assess dietary habits, sleep quality, depression, and quality of life. Following baseline assessments, participants will be randomised to either 2 g carnosine or placebo for 15 weeks. In the 15th week, all assessments will be repeated. The preplanned outcome metric is the change between baseline and follow-up measures.

ETHICS AND DISSEMINATION

This study is approved by the Human Research Ethics Committee of Monash Health and Monash University, Australia.

TRIAL REGISTRATION NUMBER

NCT02686996.

Ocular growth and metabolomics are dependent upon the spectral content of ambient white light

Myopia results from an excessive axial growth of the eye, causing abnormal projection of remote images in front of the retina. Without adequate interventions, myopia is forecasted to affect 50% of the world population by 2050. Exposure to outdoor light plays a critical role in preventing myopia in children, possibly through the brightness and blue-shifted spectral composition of sunlight, which lacks in artificial indoor lighting. Here, we evaluated the impact of moderate levels of ambient standard white (SW: 233.1 lux, 3900 K) and blue-enriched white (BEW: 223.8 lux, 9700 K) lights on ocular growth and metabolomics in a chicken-model of form-deprivation myopia. Compared to SW light, BEW light decreased aberrant ocular axial elongation and accelerated recovery from form-deprivation. Furthermore, the metabolomic profiles in the vitreous and retinas of recovering form-deprived eyes were distinct from control eyes and were dependent on the spectral content of ambient light. For instance, exposure to BEW light was associated with deep lipid remodeling and metabolic changes related to energy production, cell proliferation, collagen turnover and nitric oxide metabolism. This study provides new insight on light-dependent modulations in ocular growth and metabolomics. If replicable in humans, our findings open new potential avenues for spectrally-tailored light-therapy strategies for myopia.

Dietary Carnitine and Carnosine Increase Body Lean in Healthy Cats in a Preliminary Study

Simple Summary

Cats, like mammals in general, experience lean body mass loss in later life. This study shows that two dietary interventions offset that loss: L-carnitine and carnosine. The combination did not change body lean. Interestingly, the combination resulted in an increased circulating concentration of 8 of the 10 cytokines measured, while L-carnitine alone resulted in decreased concentrations. Thus, L-carnitine could benefit the healthy cat while in some disease states it may be beneficial to increase both L-carnitine and carnosine.

Abstract

The need to maintain body lean as cats age is shown in both health and disease. In healthy cats, body lean is associated with enhanced movement and overall longevity. In many disease states (i.e., renal disease, obesity), an enhanced or minimally maximal support of body lean is associated with quality of life and is a nutritional goal in aiding in the management of the disease. This study was designed to investigate the effect of these two dietary components and their combination on body composition and circulating factors of health, including metabolomics analysis and cytokine concentration. The foods that were fed for 169 days to four groups of cats and consisted of control food (formulated to meet the nutritional needs of all adult cats), carnitine-enhanced food (control food plus 300 mg/kg L-carnitine), carnosine-enhanced food (control food plus 1000 mg/kg carnosine), and food enhanced with both (control plus 300 mg/kg carnitine and 1000 mg/kg carnosine). Dietary enhancement with L-carnitine and carnosine increased body lean at the end of the study compared to the cats consuming the control food or the combination food. The cats consuming L-carnitine alone had a decreased concentration of circulating cytokines, while those consuming the combination food had an increased concentration of glucose, pyruvate, succinate, and circulating cytokines.

Expeller-Pressed Canola (Brassica napus) Meal Modulates the Structure and Function of the Cecal Microbiota, and Alters the Metabolome of the Pancreas, Liver, and Breast Muscle of Broiler Chickens

The inoculation of one-day-old broiler chicks with the cecal contents from a mature broiler breeder resulted in a highly diverse and uniform cecal bacterial community. CM did not affect feed consumption, weight gain, nor the richness, evenness, or diversity of the cecal bacterial community. However, the structure of the bacterial community was altered in birds fed the CM diet. Although the CM diet was formulated to contain equivalent metabolizable energy to the control diet, it contained more dietary fiber. The abundance of bacterial families, including those that are known to contain species able to metabolize fiber was altered (e.g., bacteria within the families, Methanobacteriaceae, Atopobiaceae, Prevotellaceae, Clostridiales Family XIII, Peptostreptococcaceae, and Succinivibrionaceae), and concentrations of SCFAs were higher in the ceca of birds fed the CM diet. Moreover, concentrations of isoleucine, isobutyrate, glutamate, and 2-oxoglutarate were higher, whereas concentrations of phenyllactic acid, indole, glucose, 3-phenylpropionate, and 2-oxobutyrate were lower in the digesta of chickens that were fed CM. The metabolic profiles of pancreas, liver, and breast muscle tissues of birds fed the CM diet differed from control birds. Metabolites that were associated with energy production, protection against oxidative stress, and pathways of amino acid and glycerophospholipid metabolism had altered concentrations in these tissues. Some of the observed changes in metabolite levels may indicate an increased disease risk in birds fed the CM diet (e.g., pancreatitis), and others suggested that birds mounted metabolic response to offset the adverse impacts of CM (e.g., oxidative stress in the liver).

Carbonyl Stress in Red Blood Cells and Hemoglobin

The paper overviews the peculiarities of carbonyl stress in nucleus-free mammal red blood cells (RBCs). Some functional features of RBCs make them exceptionally susceptible to reactive carbonyl compounds (RCC) from both blood plasma and the intracellular environment. In the first case, these compounds arise from the increased concentrations of glucose or ketone bodies in blood plasma, and in the second-from a misbalance in the glycolysis regulation. RBCs are normally exposed to RCC-methylglyoxal (MG), triglycerides-in blood plasma of diabetes patients. MG modifies lipoproteins and membrane proteins of RBCs and endothelial cells both on its own and with reactive oxygen species (ROS). Together, these phenomena may lead to arterial hypertension, atherosclerosis, hemolytic anemia, vascular occlusion, local ischemia, and hypercoagulation phenotype formation. ROS, reactive nitrogen species (RNS), and RCC might also damage hemoglobin (Hb), the most common protein in the RBC cytoplasm. It was Hb with which non-enzymatic glycation was first shown in living systems under physiological conditions. Glycated HbA1c is used as a very reliable and useful diagnostic marker. Studying the impacts of MG, ROS, and RNS on the physiological state of RBCs and Hb is of undisputed importance for basic and applied science.

Whole Blood Metabolomics in Aging Research

Diversity is observed in the wave of global aging because it is a complex biological process exhibiting individual variability. To assess aging physiologically, markers for biological aging are required in addition to the calendar age. From a metabolic perspective, the aging hypothesis includes the mitochondrial hypothesis and the calorie restriction (CR) hypothesis. In experimental models, several compounds or metabolites exert similar lifespan-extending effects, like CR. However, little is known about whether these metabolic modulations are applicable to human longevity, as human aging is greatly affected by a variety of factors, including lifestyle, genetic or epigenetic factors, exposure to stress, diet, and social environment. A comprehensive analysis of the human blood metabolome captures complex changes with individual differences. Moreover, a non-targeted analysis of the whole blood metabolome discloses unexpected aspects of human biology. By using such approaches, markers for aging or aging-relevant conditions were identified. This information should prove valuable for future diagnosis or clinical interventions in diseases relevant to aging.

Deorphaning a solute carrier 22 family member, SLC22A15, through functional genomic studies

The human solute carrier 22A (SLC22A) family consists of 23 members, representing one of the largest families in the human SLC superfamily. Despite their pharmacological and physiological importance in the absorption and disposition of a range of solutes, eight SLC22A family members remain classified as orphans. In this study, we used a multifaceted approach to identify ligands of orphan SLC22A15. Ligands of SLC22A15 were proposed based on phylogenetic analysis and comparative modeling. The putative ligands were then confirmed by metabolomic screening and uptake assays in SLC22A15 transfected HEK293 cells. Metabolomic studies and transporter assays revealed that SLC22A15 prefers zwitterionic compounds over cations and anions. We identified eight zwitterions, including ergothioneine, carnitine, carnosine, gabapentin, as well as four cations, including MPP⁺ , thiamine, and cimetidine, as substrates of SLC22A15. Carnosine was a specific substrate of SLC22A15 among the transporters in the SLC22A family. SLC22A15 transport of several substrates was sodium-dependent and exhibited a higher Km for ergothioneine, carnitine, and carnosine compared to previously identified transporters for these ligands. This is the first study to characterize the function of SLC22A15. Our studies demonstrate that SLC22A15 may play an important role in determining the systemic and tissue levels of ergothioneine, carnosine, and other zwitterions.

Effects of carnosine on apoptosis, transient receptor potential melastatin 2, and betatrophin in rats exposed to formaldehyde

We investigated the effects of exposure to formaldehyde on transient receptor potential melastatin 2, betatrophin, total oxidant status and total antioxidant status in rat liver and kidney tissues. We also investigated the effects of carnosine on formaldehyde treated animals. We used 28 male rats divided ramdomly into four groups of seven: untreated control group, carnosine treated group, formaldehyde treated group and formaldehyde + carnosine group. The experiment lasted for four weeks. Betatrophin levels in samples were measured uing the enzyme-linked immunosorbent assay, and total oxidant status and total antioxidant status were measured using REL assay diagnostic kits. We detected betatrophin and transient receptor potential melastatin 2 immunoreactivity using immunohistochemistry and assessed apoptosis using terminal deoxynucleotidyl transferase dUTP nick end labeling. The betatrophin and total antioxidant status levels decreased in kidney, liver and plasma following exposure to formaldehyde, while total oxidant status and terminal deoxynucleotidyl transferase dUTP nick end labeling positivity increased. Carnosine supplementation reversed histopathology and biochemical damage caused by formaldehyde. We suggest that carnosine treatment may be useful for protecting persons exposed to formaldehyde.

Complexity in Lipid Membrane Composition Induces Resilience to Aβ42 Aggregation

The molecular origins of Alzheimer's disease are associated with the aggregation of the amyloid-β peptide (Aβ). This process is controlled by a complex cellular homeostasis system, which involves a variety of components, including proteins, metabolites, and lipids. It has been shown in particular that certain components of lipid membranes can speed up Aβ aggregation. This observation prompts the question of whether there are protective cellular mechanisms to counterbalance this effect. Here, to address this issue, we investigate the role of the composition of lipid membranes in modulating the aggregation process of Aβ. By adopting a chemical kinetics approach, we first identify a panel of lipids that affect the aggregation of the 42-residue form of Aβ (Aβ₄₂), ranging from enhancement to inhibition. We then show that these effects tend to average out in mixtures of these lipids, as such mixtures buffer extreme aggregation behaviors as the number of components increases. These results indicate that a degree of quality control on protein aggregation can be achieved through a mechanism by which an increase in the molecular complexity of lipid membranes balances opposite effects and creates resilience to aggregation.

The Urinary Metabolome of Healthy Newborns

The knowledge of normal metabolite values for neonates is key to establishing robust cut-off values to diagnose diseases, to predict the occurrence of new diseases, to monitor a neonate's metabolism, or to assess their general health status. For full term-newborns, many reference biochemical values are available for blood, serum, plasma and cerebrospinal fluid. However, there is a surprising lack of information about normal urine concentration values for a large number of important metabolites in neonates. In the present work, we used targeted tandem mass spectrometry (MS/MS)-based metabolomic assays to identify and quantify 136 metabolites of biomedical interest in the urine from 48 healthy, full-term term neonates, collected in the first 24 h of life. In addition to this experimental study, we performed a literature review (covering the past eight years and over 500 papers) to update the references values in the Human Metabolome Database/Urine Metabolome Database (HMDB/UMDB). Notably, 86 of the experimentally measured urinary metabolites are being reported in neonates/infants for the first time and another 20 metabolites are being reported in human urine for the first time ever. Sex differences were found for 15 metabolites. The literature review allowed us to identify another 78 urinary metabolites with concentration data. As a result, reference concentration values and ranges for 378 neonatal urinary metabolites are now publicly accessible via the HMDB.

Scientific Papers and Patents on Substances with Unproven Effects

It is evident from reviewing scientific literature that the quality of argumentation in some areas of medical research has deteriorated during the last decades. Publication of a series of questionable reliability has continued without making references to the published criticism; examples are discussed in this review. Another tendency is that drugs without proven efficiency are advertised, corresponding products patented and marketed as evidence-based medications. Professional publications are required to register drugs and dietary supplements to obtain permissions for the practical use; and such papers appeared, sometimes being of questionable reliability. Several examples are discussed in this review when substances without proven effects were patented and introduced into practice being supported by publications of questionable reliability. Some of the topics are not entirely clear; and the arguments provided here can induce a constructive discussion.

Investigation on beneficial role of l-carnosine in neuroprotective mechanism of ischemic postconditioning in mice: possible role of histidine histamine pathway

OBJECTIVE

The present study was undertaken to investigate the possible role of histidine-histamine pathway in the neuroprotective effects produced by L-carnosine hand in hand with ischemic postconditioning in the animal model of cerebral ischemia.

METHODS

Cerebral ischemia was induced in swiss albino mice by performing BCCAO surgery. Morris water-maze test was utilized to assess the learning ability and memory of the animals. The whole brain acetylcholinesterase (AChE) activity, TBARS, GSH levels and MPO activity were evaluated as the biochemical parameters. For histopathological evaluation of the cerebral infarct size, TTC staining was employed.

RESULTS

Administration of L-carnosine (500   mg/kg, i.p.) successfully attenuated the manifestations of cerebral ischemia. Higher levels of AChE, TBARS, and MPO were observed in BCCAO treated animals, which were successfully attenuated by treatment with L-carnosine and ischemic postconditioning. Whereas administration of L-carnosine and ischemic postconditioning significantly increased the level of GSH in BCCAO treated animals. Moreover, treatment with ranitidine, an H₂ blocker (30 NMol, i.c.v) antagonized the neuroprotective actions of L-carnosine evidenced by decrease in MWM performance, increase in the level of AChE and oxidative stress, while decrease in GSH level in brain. The cerebral infarct size was found to be more in BCCAO inflicted animals, which was improved by the administration of L-carnosine, while the cerebral infarct size worsened by treatment with ranitidine (3   nmol, i.c.v.).

CONCLUSION

It is concluded that L-carnosine exerts neuroprotective effect via involvement of histidine-histamine pathway since the beneficial effects of L-carnosine were abolished by the H₂-blocker.

Synthesis of radioiodinated carnosine for hepatotoxicity imaging induced by carbon tetrachloride and its biological assessment in rats

The imaging of organs is very important in the field of diagnosis especially in case of liver diseases. In the present work, carnosine was successfully labeled with iodine-131 at room temperature in acidic medium using chloramine-T (Ch-T) as moderate oxidizing agent. The parameters affecting labeling of carnosine such as amount of oxidizing agent, amount of substrate, pH value of the reaction mixture, reaction temperature and reaction time, were investigated. The best conditions for formation of 131I-carnosine (131I-CAR) complex were 40 μg of chloramine-T (Ch-T), 75 μg of carnosine, pH 4 and 45 min reaction time at room temperature. The radiochemical yield for 131I-CAR complex was (91 ± 0.11) % at optimum conditions and the labeled complex was stable for 2 h after labeling process. Biodistribution study was achieved using three groups of rats (normal, treated by inactive carnosine and hepatotoxicity rats induced by CCl4). Hepatotoxicity of liver was evaluated using different biochemical markers such as ALT, AST and ALK.P. The 131I-CAR complex showed selective bio-localization in stomach and liver and its selectivity increases in acquired hepatotoxicity. The biological distribution indicates that the suitability of 131I-CAR as a potential hepatotoxicity imaging to detect hepatitis and medical prognosis.

Characteristics of Selected Antioxidative and Bioactive Compounds in Meat and Animal Origin Products

Meat and meat products have a high nutritional value. Besides major components, meat is rich in bioactive components, primarily taurine, l-carnitine, choline, alpha-lipoic acid, conjugated linoleic acid, glutathione, creatine, coenzyme Q10 and bioactive peptides. Many studies have reported their antioxidant and health-promoting properties connected with their lipid-lowering, antihypertensive, anti-inflammatory, immunomodulatory activity and protecting the organism against oxidative stress. The antioxidant activity of meat components results, among others, from the capability of scavenging reactive oxygen and nitrogen species, forming complexes with metal ions and protecting cells against damage. This review is focused to gather accurate information about meat components with antioxidant and biological activity.

Carnosine Decreases PMA-Induced Oxidative Stress and Inflammation in Murine Macrophages

Carnosine is an endogenous dipeptide composed of β-alanine and L-histidine. This naturally occurring molecule is present at high concentrations in several mammalian excitable tissues such as muscles and brain, while it can be found at low concentrations in a few invertebrates. Carnosine has been shown to be involved in different cellular defense mechanisms including the inhibition of protein cross-linking, reactive oxygen and nitrogen species detoxification as well as the counteraction of inflammation. As a part of the immune response, macrophages are the primary cell type that is activated. These cells play a crucial role in many diseases associated with oxidative stress and inflammation, including atherosclerosis, diabetes, and neurodegenerative diseases. In the present study, carnosine was first tested for its ability to counteract oxidative stress. In our experimental model, represented by RAW 264.7 macrophages challenged with phorbol 12-myristate 13-acetate (PMA) and superoxide dismutase (SOD) inhibitors, carnosine was able to decrease the intracellular concentration of superoxide anions (O2-•) as well as the expression of Nox1 and Nox2 enzyme genes. This carnosine antioxidant activity was accompanied by the attenuation of the PMA-induced Akt phosphorylation, the down-regulation of TNF-α and IL-6 mRNAs, and the up-regulation of the expression of the anti-inflammatory mediators IL-4, IL-10, and TGF-β1. Additionally, when carnosine was used at the highest dose (20 mM), there was a generalized amelioration of the macrophage energy state, evaluated through the increase both in the total nucleoside triphosphate concentrations and the sum of the pool of intracellular nicotinic coenzymes. Finally, carnosine was able to decrease the oxidized (NADP+)/reduced (NADPH) ratio of nicotinamide adenine dinucleotide phosphate in a concentration dependent manner, indicating a strong inhibitory effect of this molecule towards the main source of reactive oxygen species in macrophages. Our data suggest a multimodal mechanism of action of carnosine underlying its beneficial effects on macrophage cells under oxidative stress and inflammation conditions.

Pivotal role of carnosine in the modulation of brain cells activity: Multimodal mechanism of action and therapeutic potential in neurodegenerative disorders

Carnosine (β-alanyl-l-histidine), a dipeptide, is an endogenous antioxidant widely distributed in excitable tissues like muscles and the brain. Although discovered more than a hundred years ago and having been extensively studied in the periphery, the role of carnosine in the brain remains mysterious. Carnosinemia, a rare metabolic disorder with increased levels of carnosine in urine and low levels or absence of carnosinase in the blood, is associated with severe neurological symptoms in humans. This review deals with the role of carnosine in the brain in both physiological and pathological conditions, with a focus on preclinical evidence suggesting a high therapeutic potential of carnosine in neurodegenerative disorders. We review carnosine and carnosinemia's discoveries and the extensive research on the role and benefits of carnosine in the periphery. We then turn to carnosine's biochemistry and distribution in the brain. Using an array of recent observations as a foundation, we draw a parallel with the role of carnosine in muscles and speculate on the role of carnosine in promoting the metabolic support of neurons by glial cells. Finally, carnosine has been shown to exert a multimodal activity including inhibition of protein cross-linking and aggregation of amyloid-β and related proteins, free radical generation, nitric oxide detoxification, and an anti-inflammatory activity. It could thus play an important role in the prevention and treatment of neurodegenerative diseases such as Alzheimer's disease. We discuss the potential of carnosine in this context and speculate on new preclinical research directions.

The Role of Advanced Glycation End Products in Aging and Metabolic Diseases: Bridging Association and Causality

Accumulation of advanced glycation end products (AGEs) on nucleotides, lipids, and peptides/proteins are an inevitable component of the aging process in all eukaryotic organisms, including humans. To date, a substantial body of evidence shows that AGEs and their functionally compromised adducts are linked to and perhaps responsible for changes seen during aging and for the development of many age-related morbidities. However, much remains to be learned about the biology of AGE formation, causal nature of these associations, and whether new interventions might be developed that will prevent or reduce the negative impact of AGEs-related damage. To facilitate achieving these latter ends, we show how invertebrate models, notably Drosophila melanogaster and Caenorhabditis elegans, can be used to explore AGE-related pathways in depth and to identify and assess drugs that will mitigate against the detrimental effects of AGE-adduct development.

Carnosine suppresses oxygen-glucose deprivation/recovery-induced proliferation and migration of reactive astrocytes of rats in vitro

Glial scar formation resulted from excessive astrogliosis limits axonal regeneration and impairs recovery of function, thus an intervention to ameliorate excessive astrogliosis is crucial for the recovery of neurological function after cerebral ischemia. In this study we investigated the effects of carnosine, an endogenous water-soluble dipeptide (β-alanyl-L-histidine), on astrogliosis of cells exposed to oxygen-glucose deprivation/recovery (OGD/R) in vitro. Primary cultured rat astrocytes exhibited a significant increase in proliferation at 24 h recovery after OGD for 2 h. Pretreatment with carnosine (5 mmol/L) caused G₁ arrest of reactive astrocytes, significantly attenuated OGD/R-induced increase in cyclin D1 protein expression and suppressed OGD/R-induced proliferation of reactive astrocytes. Carnosine treatment also reversed glycolysis and ATP production, which was elevated at 24 h recovery after OGD. A marked increase in migration of reactive astrocytes was observed at 24 h after OGD, whereas carnosine treatment reversed the expression levels of MMP-9 and suppressed the migration of astrocytes. Furthermore, carnosine also improved neurite growth of cortical neurons co-cultured with astrocytes under ischemic conditions. These results demonstrate that carnosine may be a promising candidate for inhibiting astrogliosis and promoting neurological function recovery after ischemic stroke.

Carnosine attenuates cyclophosphamide-induced bone marrow suppression by reducing oxidative DNA damage

Oxidative DNA damage in bone marrow cells is the main side effect of chemotherapy drugs including cyclophosphamide (CTX). However, not all antioxidants are effective in inhibiting oxidative DNA damage. In this study, we report the beneficial effect of carnosine (β-alanyl-l-histidine), a special antioxidant with acrolein-sequestering ability, on CTX-induced bone marrow cell suppression. Our results show that carnosine treatment (100 and 200 mg/kg, i.p.) significantly inhibited the generation of reactive oxygen species (ROS) and 8-hydroxy-2′-deoxyguanosine (8-oxo-dG), and decreased chromosomal abnormalities in the bone marrow cells of mice treated with CTX (20 mg/kg, i.v., 24 h). Furthermore, carnosine evidently mitigated CTX-induced G2/M arrest in murine bone marrow cells, accompanied by reduced ratios of p-Chk1/Chk1 and p-p53/p53 as well as decreased p21 expression. In addition, cell apoptosis caused by CTX was also suppressed by carnosine treatment, as assessed by decreased TUNEL-positive cell counts, down-regulated expressions of Bax and Cyt c, and reduced ratios of cleaved Caspase-3/Caspase-3. These results together suggest that carnosine can protect murine bone marrow cells from CTX-induced DNA damage via its antioxidant activity.

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Bone marrow cells suppression induced by CTX is associated with the increasement of ROS and oxidative DNA damage.

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Carnosine attenuates CTX-elevated oxidative DNA damage and bone marrow cells suppression.

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Favorable prospects of clinical applications for carnosine in combination with CTX.

Methylglyoxal-Mediated Stress Correlates with High Metabolic Activity and Promotes Tumor Growth in Colorectal Cancer

Cancer cells generally rely on aerobic glycolysis as a major source of energy. Methylglyoxal (MG), a dicarbonyl compound that is produced as a side product during glycolysis, is highly reactive and induces the formation of advanced glycation end-products that are implicated in several pathologies including cancer. All mammalian cells have an enzymatic defense against MG composed by glyoxalases GLO1 and GLO2 that converts MG to d-lactate. Colorectal cancer (CRC) is one of the most frequently occurring cancers with high morbidity and mortality. In this study, we used immunohistochemistry to examine the level of MG protein adducts, in a series of 102 CRC human tumors divided into four clinical stages. We consistently detected a high level of MG adducts and low GLO1 activity in high stage tumors compared to low stage ones suggesting a pro-tumor role for dicarbonyl stress. Accordingly, GLO1 depletion in CRC cells promoted tumor growth in vivo that was efficiently reversed using carnosine, a potent MG scavenger. Our study represents the first demonstration that MG adducts accumulation is a consistent feature of high stage CRC tumors. Our data point to MG production and detoxification levels as an important molecular link between exacerbated glycolytic activity and CRC progression.

Individual variability in human blood metabolites identifies age-related differences

Metabolites present in human blood document individual physiological states influenced by genetic, epigenetic, and lifestyle factors. Using high-resolution liquid chromatography-mass spectrometry (LC-MS), we performed nontargeted, quantitative metabolomics analysis in blood of 15 young (29 ± 4 y of age) and 15 elderly (81 ± 7 y of age) individuals. Coefficients of variation (CV = SD/mean) were obtained for 126 blood metabolites of all 30 donors. Fifty-five RBC-enriched metabolites, for which metabolomics studies have been scarce, are highlighted here. We found 14 blood compounds that show remarkable age-related increases or decreases; they include 1,5-anhydroglucitol, dimethyl-guanosine, acetyl-carnosine, carnosine, ophthalmic acid, UDP-acetyl-glucosamine,N-acetyl-arginine,N6-acetyl-lysine, pantothenate, citrulline, leucine, isoleucine, NAD(+), and NADP(+) Six of them are RBC-enriched, suggesting that RBC metabolomics is highly valuable for human aging research. Age differences are partly explained by a decrease in antioxidant production or increasing inefficiency of urea metabolism among the elderly. Pearson's coefficients demonstrated that some age-related compounds are correlated, suggesting that aging affects them concomitantly. Although our CV values are mostly consistent with those CVs previously published, we here report previously unidentified CVs of 51 blood compounds. Compounds having moderate to high CV values (0.4-2.5) are often modified. Compounds having low CV values, such as ATP and glutathione, may be related to various diseases because their concentrations are strictly controlled, and changes in them would compromise health. Thus, human blood is a rich source of information about individual metabolic differences.

Can adaptation to nitrate supplementation and provision of fermentable energy reduce nitrite accumulation in rumen contents in vitro?

Nitrate (NO3–) supplementation is a promising methane mitigation strategy for ruminants, but can cause nitrite (NO2–) poisoning. Because some nitrite reductases are NADH-dependent, we hypothesised that replacing glucose with glycerol would increase the NADH yield and so enhance nitrite reductase activity and reduce ruminal NO2– accumulation and toxicity risk. We also hypothesised that adapting sheep to dietary NO3– would limit the accumulation of NO2– when NO3– was added to rumen fluid. Changes in NO3– and NO2– catabolism and CH4 production, resulting from supplementation with glycerol to enhance NADH supply, were studied in vitro. In Experiment 1, rumen fluid from sheep adapted to dietary NO3– (2% of DM intake) or urea (1.1% of DM intake) was incubated with NO3– or urea, respectively. Additionally, ground oaten hay was added to incubations alone (control), or with glucose or glycerol. In Experiement 2, sheep were adapted for 9 weeks to dietary NO3– or urea. Nitrate (2% NO3– of substrate DM) was added to incubated digesta from NO3–- or urea-supplemented sheep, while urea (1.1% of substrate DM) was added to digesta from urea-supplemented sheep. In both studies, triplicate incubations were terminated at nine time points up to 24 h. Methane emissions were lower in all NO3– treatments (P < 0.05). Contrary to our hypotheses, both glycerol supplementation (Experiment 1) and prior adaptation to NO3– (Experiment 2) increased NO2– accumulation. In Experiment 1, there was no difference in ruminal NO2– concentration between the unsupplemented control and added glucose treatments. Nitrous oxide accumulated in NO3– treatments only with rumen fluid from sheep adapted to dietary urea (P < 0.05). In summary, NO2– accumulation in vitro was not reduced by adaptation to NO3– or by glucose or glycerol supplementation, disproving the hypotheses regarding the role of NADH availability and of NO2– adaptation in reducing ruminal NO2– accumulation and toxicity risk.

Carnosine and Related Peptides: Therapeutic Potential in Age-Related Disorders

Imidazole dipeptides (ID), such as carnosine (β-alanyl-L-histidine), are compounds widely distributed in excitable tissues of vertebrates. ID are also endowed of several biochemical properties in biological tissues, including antioxidant, bivalent metal ion chelating, proton buffering, and carbonyl scavenger activities. Furthermore, remarkable biological effects have been assigned to such compounds in age-related human disorders and in patients whose activity of serum carnosinase is deficient or undetectable. Nevertheless, the precise biological role of ID is still to be unraveled. In the present review we shall discuss some evidences from clinical and basic studies for the utilization of ID as a drug therapy for age-related human disorders.

International society of sports nutrition position stand: Beta-Alanine

The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the mechanisms and use of beta-alanine supplementation. Based on the current available literature, the conclusions of the ISSN are as follows: 1) Four weeks of beta-alanine supplementation (4-6 g daily) significantly augments muscle carnosine concentrations, thereby acting as an intracellular pH buffer; 2) Beta-alanine supplementation currently appears to be safe in healthy populations at recommended doses; 3) The only reported side effect is paraesthesia (tingling), but studies indicate this can be attenuated by using divided lower doses (1.6 g) or using a sustained-release formula; 4) Daily supplementation with 4 to 6 g of beta-alanine for at least 2 to 4 weeks has been shown to improve exercise performance, with more pronounced effects in open end-point tasks/time trials lasting 1 to 4 min in duration; 5) Beta-alanine attenuates neuromuscular fatigue, particularly in older subjects, and preliminary evidence indicates that beta-alanine may improve tactical performance; 6) Combining beta-alanine with other single or multi-ingredient supplements may be advantageous when supplementation of beta-alanine is high enough (4-6 g daily) and long enough (minimum 4 weeks); 7) More research is needed to determine the effects of beta-alanine on strength, endurance performance beyond 25 min in duration, and other health-related benefits associated with carnosine.

Carnosine: effect on aging-induced increase in brain regional monoamine oxidase-A activity

Aging is a natural biological process associated with several neurological disorders along with the biochemical changes in brain. Aim of the present investigation is to study the effect of carnosine (0.5-2.5μg/kg/day, i.t. for 21 consecutive days) on aging-induced changes in brain regional (cerebral cortex, hippocampus, hypothalamus and pons-medulla) mitochondrial monoamine oxidase-A (MAO-A) activity with its kinetic parameters. The results of the present study are: (1) The brain regional mitochondrial MAO-A activity and their kinetic parameters (except in Km of pons-medulla) were significantly increased with the increase of age (4-24 months), (2) Aging-induced increase of brain regional MAO-A activity including its Vmax were attenuated with higher dosages of carnosine (1.0-2.5μg/kg/day) and restored toward the activity that observed in young, though its lower dosage (0.5μg/kg/day) were ineffective in these brain regional MAO-A activity, (3) Carnosine at higher dosage in young rats, unlike aged rats significantly inhibited all the brain regional MAO-A activity by reducing their only Vmax excepting cerebral cortex, where Km was also significantly enhanced. These results suggest that carnosine attenuated the aging-induced increase of brain regional MAO-A activity by attenuating its kinetic parameters and restored toward the results of MAO-A activity that observed in corresponding brain regions of young rats.

Validation of a blood protein signature for non-small cell lung cancer

Background

CT screening for lung cancer is effective in reducing mortality, but there are areas of concern, including a positive predictive value of 4% and development of interval cancers. A blood test that could manage these limitations would be useful, but development of such tests has been impaired by variations in blood collection that may lead to poor reproducibility across populations.

Results

Blood-based proteomic profiles were generated with SOMAscan technology, which measured 1033 proteins. First, preanalytic variability was evaluated with Sample Mapping Vectors (SMV), which are panels of proteins that detect confounders in protein levels related to sample collection. A subset of well collected serum samples not influenced by preanalytic variability was selected for discovery of lung cancer biomarkers. The impact of sample collection variation on these candidate markers was tested in the subset of samples with higher SMV scores so that the most robust markers could be used to create disease classifiers. The discovery sample set (n = 363) was from a multi-center study of 94 non-small cell lung cancer (NSCLC) cases and 269 long-term smokers and benign pulmonary nodule controls. The analysis resulted in a 7-marker panel with an AUC of 0.85 for all cases (68% adenocarcinoma, 32% squamous) and an AUC of 0.93 for squamous cell carcinoma in particular. This panel was validated by making blinded predictions in two independent cohorts (n = 138 in the first validation and n = 135 in the second). The model was recalibrated for a panel format prior to unblinding the second cohort. The AUCs overall were 0.81 and 0.77, and for squamous cell tumors alone were 0.89 and 0.87. The estimated negative predictive value for a 15% disease prevalence was 93% overall and 99% for squamous lung tumors. The proteins in the classifier function in destruction of the extracellular matrix, metabolic homeostasis and inflammation.

Conclusions

Selecting biomarkers resistant to sample processing variation led to robust lung cancer biomarkers that performed consistently in independent validations. They form a sensitive signature for detection of lung cancer, especially squamous cell histology. This non-invasive test could be used to improve the positive predictive value of CT screening, with the potential to avoid invasive evaluation of nonmalignant pulmonary nodules.

Modulation of mitochondrial function and autophagy mediates carnosine neuroprotection against ischemic brain damage

BACKGROUND AND PURPOSE

Despite the rapidly increasing global burden of ischemic stroke, no therapeutic options for neuroprotection against stroke currently exist. Recent studies have shown that autophagy plays a key role in ischemic neuronal death, and treatments that target autophagy may represent a novel strategy in neuroprotection. We investigated whether autophagy is regulated by carnosine, an endogenous pleiotropic dipeptide that has robust neuroprotective activity against ischemic brain damage.

METHODS

We examined the effect of carnosine on mitochondrial dysfunction and autophagic processes in rat focal ischemia and in neuronal cultures.

RESULTS

Autophagic pathways such as reduction of phosphorylated mammalian target of rapamycin (mTOR)/p70S6K and the conversion of microtubule-associated protein 1 light chain 3 (LC3)-I to LC3-II were enhanced in the ischemic brain. However, treatment with carnosine significantly attenuated autophagic signaling in the ischemic brain, with improvement of brain mitochondrial function and mitophagy signaling. The protective effect of carnosine against autophagy was also confirmed in primary cortical neurons.

CONCLUSIONS

Taken together, our data suggest that the neuroprotective effect of carnosine is at least partially mediated by mitochondrial protection and attenuation of deleterious autophagic processes. Our findings shed new light on the mechanistic pathways that this exciting neuroprotective agent influences.

Carnosine inhibits carbonic anhydrase IX-mediated extracellular acidosis and suppresses growth of HeLa tumor xenografts

BACKGROUND

Carbonic anhydrase IX (CA IX) is a transmembrane enzyme that is present in many types of solid tumors. Expression of CA IX is driven predominantly by the hypoxia-inducible factor (HIF) pathway and helps to maintain intracellular pH homeostasis under hypoxic conditions, resulting in acidification of the tumor microenvironment. Carnosine (β-alanyl-L-histidine) is an anti-tumorigenic agent that inhibits the proliferation of cancer cells. In this study, we investigated the role of CA IX in carnosine-mediated antitumor activity and whether the underlying mechanism involves transcriptional and translational modulation of HIF-1α and CA IX and/or altered CA IX function.

METHODS

The effect of carnosine was studied using two-dimensional cell monolayers of several cell lines with endogenous CA IX expression as well as Madin Darby canine kidney transfectants, three-dimensional HeLa spheroids, and an in vivo model of HeLa xenografts in nude mice. mRNA and protein expression and protein localization were analyzed by real-time PCR, western blot analysis, and immunofluorescence staining, respectively. Cell viability was measured by a flow cytometric assay. Expression of HIF-1α and CA IX in tumors was assessed by immunohistochemical staining. Real-time measurement of pH was performed using a sensor dish reader. Binding of CA IX to specific antibodies and metabolon partners was investigated by competitive ELISA and proximity ligation assays, respectively.

RESULTS

Carnosine increased the expression levels of HIF-1α and HIF targets and increased the extracellular pH, suggesting an inhibitory effect on CA IX-mediated acidosis. Moreover, carnosine significantly inhibited the growth of three-dimensional spheroids and tumor xenografts compared with untreated controls. Competitive ELISA showed that carnosine disrupted binding between CA IX and antibodies specific for its catalytic domain. This finding was supported by reduced formation of the functional metabolon of CA IX and anion exchanger 2 in the presence of carnosine.

CONCLUSIONS

Our results indicate that interaction of carnosine with CA IX leads to conformational changes of CA IX and impaired formation of its metabolon, which in turn disrupts CA IX function. These findings suggest that carnosine could be a promising anticancer drug through its ability to attenuate the activity of CA IX.

Plasma amino acid profiles of breast cancer patients early in the trajectory of the disease differ from healthy comparison groups

This study describes and compares fasting plasma amino acid profiles of breast cancer patients near the initiation of chemotherapy with those of healthy age- and body mass index-matched females (HM), as well as young healthy females (HY). Breast cancer patients had significantly greater glutamate and histidine concentrations and significantly lower threonine concentrations compared with HM and HY females independent of protein or caloric intake. These differences may be related to metabolic perturbations associated with the disease.

Impairment of electron transfer chain induced by acute carnosine administration in skeletal muscle of young rats

Serum carnosinase deficiency is an inherited disorder that leads to an accumulation of carnosine in the brain tissue, cerebrospinal fluid, skeletal muscle, and other tissues of affected patients. Considering that high levels of carnosine are associated with neurological dysfunction and that the pathophysiological mechanisms involved in serum carnosinase deficiency remain poorly understood, we investigated the in vivo effects of carnosine on bioenergetics parameters, namely, respiratory chain complexes (I–III, II, and II-III), malate dehydrogenase, succinate dehydrogenase, and creatine kinase activities and the expression of mitochondrial-specific transcription factors (NRF-1, PGC-1α, and TFAM) in skeletal muscle of young Wistar rats. We observed a significant decrease of complexes I–III and II activities in animals receiving carnosine acutely, as compared to control group. However, no significant alterations in respiratory chain complexes, citric acid cycle enzymes, and creatine kinase activities were found between rats receiving carnosine chronically and control group animals. As compared to control group, mRNA levels of NRF-1, PGC-1α, and TFAM were unchanged. The present findings indicate that electron transfer through the respiratory chain is impaired in skeletal muscle of rats receiving carnosine acutely. In case these findings are confirmed by further studies and ATP depletion is also observed, impairment of bioenergetics could be considered a putative mechanism responsible for the muscle damage observed in serum carnosinase-deficient patients.

Metabolic profiling reveals therapeutic biomarkers of processed Aconitum carmichaeli Debx in treating hydrocortisone induced kidney-yang deficiency syndrome rats

ETHNOPHARMACOLOGICAL RELEVANCE

Kidney-yang deficiency syndrome (KYDS) is a diagnostic pattern in traditional Chinese medicine (TCM) and clinical data showed that the unbalance in adrenal cortical hormone is the key issue in KYDS patients. The processed Ranunculaceae aconitum carmichaeli debx (bai-fu-pian in Chinese, BFP) is one of the most commonly used Chinese herbs for treating KYDS. The present study was conducted to explore the therapeutic biomarkers of the BFP in treating hydrocortisone administration induced KYDS rats.

MATERIALS AND METHODS

Thirty male Sprague-Dawley rats were randomly divided into five groups with six in each group. KYDS in rats was induced by i.p. injection of hydrocortisone at the dose of 10mg/kg per day for 15 days as described previously. The rats with KYDS were administered orally, starting from the day of hydrocortisone administration stopped, with BFP extract at the dose of 0.32g/kg, 0.64g/kg and 1.28g/kg per day respectively for 15 days. The blood samples were collected for the liquid chromatography quadruple time-of-flight mass spectrometry (LC-Q-TOF-MS) test, as well as radioimmunoassay to determine the concentrations of cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP) and adrenocorticotrophic hormone (ACTH). The metabolic responses to BFP administration were investigated by using the principal components analysis (PCA) and orthogonal partial least squares analysis (OPLS). Bioinformatics analyses were performed by using the Ingenuity Pathway Analysis (IPA). Variance analysis and linear regression analysis were used in this study.

RESULTS

The signs and concentrations of cAMP, cGMP and ACTH in the model rats were similar to those previously described about KYDS rats and BFP treatment can reverse the changes. Seventeen significantly changed metabolites among different groups were identified. Thirteen metabolites were identified in the KYDS rats comparing to healthy rats with nine up-regulated and four down-regulated. After BFP treatment at three dosages, five up-regulated metabolites including phosphate, betaine, (4-hydroxyphenyl) acetaldehyde, 5-hydroxyindol-3-acetic acid and 5'-phosphoribosyl-N-formylglycinamide were dose-dependently reversed. The network analysis with IPA showed that four canonical pathways including superpathway of methionine degradation, purine nucleotides de novo biosynthesis II, tyrosine synthesis and serotonin receptor signaling involved the therapeutic mechanism of BFP in treating the KYDS rats.

CONCLUSIONS

Five therapeutic biomarkers (phosphate, betaine, (4-hydroxyphenyl) acetaldehyde, 5-hydroxyindol-3-acetic acid and 5'-phosphoribosyl-N-formylglycinamide) and two corresponding canonical pathways (amino acid metabolism and purine nucleotide metabolism) were identified to be involved in the therapeutic mechanism of BFP treating the KYDS.

Pharmacogenomics of Alzheimer's disease: novel therapeutic strategies for drug development

Alzheimer's disease (AD) is a major problem of health and disability, with a relevant economic impact on our society. Despite important advances in pathogenesis, diagnosis, and treatment, its primary causes still remain elusive, accurate biomarkers are not well characterized, and the available pharmacological treatments are not cost-effective. As a complex disorder, AD is a polygenic and multifactorial clinical entity in which hundreds of defective genes distributed across the human genome may contribute to its pathogenesis. Diverse environmental factors, cerebrovascular dysfunction, and epigenetic phenomena, together with structural and functional genomic dysfunctions, lead to amyloid deposition, neurofibrillary tangle formation, and premature neuronal death, the major neuropathological hallmarks of AD. Future perspectives for the global management of AD predict that genomics and proteomics may help in the search for reliable biomarkers. In practical terms, the therapeutic response to conventional drugs (cholinesterase inhibitors, multifactorial strategies) is genotype-specific. Genomic factors potentially involved in AD pharmacogenomics include at least five categories of gene clusters: (1) genes associated with disease pathogenesis; (2) genes associated with the mechanism of action of drugs; (3) genes associated with drug metabolism (phase I and II reactions); (4) genes associated with drug transporters; and (5) pleiotropic genes involved in multifaceted cascades and metabolic reactions. The implementation of pharmacogenomic strategies will contribute to optimize drug development and therapeutics in AD and related disorders.