Citrate Levels Research Articles

1H NMR-Based Metabolic Signatures in the Liver and Brain in a Rat Model of Hepatic Encephalopathy

Hepatic encephalopathy (HE) is a debilitating neuropsychiatric complication associated with acute and chronic liver failure. It is characterized by diverse symptoms with variable severity that includes cognitive and motor deficits. The aim of the study is to assess metabolic alterations in the brain and liver using nuclear magnetic resonance (NMR) spectroscopy and subsequent multivariate analyses to characterize metabolic signatures associated with HE. HE was developed by bile duct ligation (BDL) that resulted in hepatic dysfunctions and cirrhosis as shown by liver function tests. Metabolic profiles from control and BDL rats indicated increased levels of lactate, branched-chain amino acids (BCAAs), glutamate, and choline in the liver, whereas levels of glucose, phenylalanine, and pyridoxine were decreased. In brain, the levels of lactate, acetate, succinate, citrate, and malate were increased, while glucose, creatine, isoleucine, leucine, and proline levels were decreased. Furthermore, neurotransmitters such as glutamate and GABA were increased, whereas choline and myo-inositol were decreased. The alterations in neurotransmitter levels resulted in cognitive and motor defects in BDL rats. A significant correlation was found among alterations in NAA/choline, choline/creatine, and NAA/creatine with behavioral deficits. Thus, the data suggests impairment in metabolic pathways such as the tricarboxylic acid (TCA) cycle, glycolysis, and ketogenesis in the liver and brain of animals with HE. The study highlights that metabolic signatures could be potential markers to monitor HE progression and to assess therapeutic interventions.

A comparative study on milk composition of Jersey and Holstein dairy cows during the early lactation.

Recently, Jersey cattle was introduced and produced by embryo transfer to Korea. This study was conducted to investigate the differences of milk compositions between Jersey and Holstein cows and the relationship between days in milk (DIM) and milk compositions during early lactation. Data were collected from twelve lactating cows from Department of Animal Resources Development at National Institute of Animal Science. Cows in parity 1 were used, and calved at spring from April to March of 2017. All cows were housed in two sections within a free-stall barn, which divided into six from each breed, and received a basal total mixed ration. Milk samples of each cow were collected at 3 DIM and 30 DIM for analyzing the milk compositions, including fatty acids (FA), amino acids and minerals. Total solids, citrate, and milk urea nitrogen level were differed between the breeds (p < 0.05). As DIM went from 3 to 30, milk protein, total solids, and somatic cell count decreased (p < 0.05), but lactose increased in all breed milk (p < 0.05). Citrate and free fatty acid (FFA) elevated in Jersey milk (p < 0.05), whereas reduced in Holstein milk (p < 0.05). Proportions of some individual FA varied from the breeds. Myristic (C14:0), palmitic (C16:0), and arachidonic acid (C20:4) in milk from all cows were higher at 3 DIM than at 30 DIM (p < 0.05). Also, stearic (C18:0) and oleic acid (C18:1) were lower at 3 DIM than at 30 DIM (p < 0.05), and the C18:1 to C18:0 ratio was significantly differed in DIM × breed interactions (p < 0.05). The contents of the individual amino acids did not differ from the breeds. Calcium, phosphorous, magnesium, and zinc (Zn) contents was significantly increased in Holstein milk than Jersey milk at 3 DIM. Also, K and Zn concentrations were higher in Holstein milk than in Jersey milk at 30 DIM (p < 0.05). It was concluded that Jersey cows would produce more effective milk in processing dairy products and more proper energy status compared with Holstein cows in early lactation under the same environmental and nutritional conditions.

P0339URINE METABOLOMIC ASSAY IN EARLY IGA NEPHROPATHY PATIENTS REVEALS URINE GLYCINE AS A PROGNOSTIC BIOMARKER

Abstract Background and Aims A urine metabolomic biomarker from early immunoglobulin A nephropathy (IgAN) can be a useful tool for early detection or prognostic prediction of the disease. Method We profiled the urine metabolomes, using nuclear magnetic resonance (NMR) spectrometry, from 197 IgAN patients with eGFR ≥ 60 mL/min/1.73 m2, and the patients with same kidney function range but have diagnosis of membranous nephropathy (n=81) and minimal change disease (n=50) were included as the disease-control group. Additional 146 healthy controls who received routine health screenings and donated urine samples were included. We calculated the creatinine-adjusted urine concentrations of 27 urine metabolites. Urine metabolites specifically increased in urines from IgAN patients were identified, and their associations with the prognosis of the disease, determined with the outcome of eGFR 30% reduction from baseline, were investigated. Additional kidney biopsy samples from independent patients and controls were stained for molecules included in related biological process for experimental validation. Results Among the 15 metabolites higher in the urines from IgAN patients than those from the healthy controls, only glycine was the metabolite that the median level was significantly higher also than that of the disease-control group. We found that the higher levels of glycine, alanine, citrate, threonine, and valine were significantly associated with higher risks of 30% eGFR reduction in IgAN patients. Among the molecules related to metabolism of glycine, expressions of T and H proteins from glycine cleavage system were significantly reduced in the kidney biopsy slides from independent IgAN patients when compared to the controls. Conclusion Urine glycine may be a prognostic and pathophysiology-related biomarker of IgAN. A further study confirming the clinical usefulness and pathophysiologic significance of urine metabolites in IgAN patients is warranted.

P0234LOW URINARY CITRATE LEVELS ARE NOT SPECIFIC OF AUTOSOMAL POLYCYSTIC KIDNEY DISEASE (ADPKD) AND ARE PRESENT WHEN RENAL FUNCTION IS IMPAIRED IN ALL NEPHROPATIES

Abstract Background and Aims In polycystic kidney disease (PKD) it is frequently found a reduction in urinary citrate that is related with degree of renal impairment but it is unknown if this alteration is specific or if it is also present in other nephropathies. Recently it has been suggested that urinary citrate could be a marker of covert metabolic acidosis and reflects acid retention in chronic kidney disease (CKD). Our aim was to compare urinary citrate in PKD with other renal diseases and to show its relation with serum bicarbonate and excretion of uric acid and calcium. Method We determined citrate, calcium and uric acid in 24-hour urine in patients with PKD and with other nephropathies with varied degree of renal impairment followed in a outpatient clinic of nephrology. Results We included 291 patients, 119 with glomerular diseases, 116 with PKD, 21 with other nephropathies, and 35 patients with normal renal function. Urinary citrate was higher in women (Females 309±251 mg/gCr vs. males 181±145 mg/gCr, p&amp;lt;0.001) and in patients with normal renal function (normal 380±210 mg/gCr; PKD 203±166 mg/gCr; glomerular 279±282 mg/gCr; p&amp;lt;0,001). PKD patients showed similar values of urinary citrate to patients with glomerular diseases and with other nephropathies. We observed a progressive reduction in urinary citrate parallel to degree of renal impairment, in a comparable way among patients with PKD and glomerular diseases. We did not observe a relationship between urinary citrate and serum bicarbonate levels. Calcium and uric acid elimination in ADPKD patients was similar to other nephropathies and lower to patients with normal renal function. However, serum uric acid was significantly higher in glomerular patients than other nephropathies after adjust with glomerular filtration rate and sex. Conclusion Hypocitraturia is not specific of PKD but it is also present in all nephropathies. Urinary citrate are related to degree of renal impairment and it is not related with serum bicarbonate. We think that it could be interesting to study urinary citrate as a marker of renal function and its role as prognostic factor of renal deterioration.

P0035URINARY CITRATE AS A MARKER OF RENAL FUNCTION IN PATIENTS WITH AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE

Abstract Background and Aims In autosomal dominant polycystic kidney disease (ADPKD) is frequent to find low urinary citrate levels. Recently it has been suggested that urinary citrate could be a marker of covert metabolic acidosis. Our aim was to analyze relationship between urinary citrate levels and renal functionality in ADPKD patients. Method We determined citrate, calcium and uric acid in 24-hour collected urine from 91 ADPKD patients Results Urinary citrate/creatinine ratio was 214±158 (range 5.3-678) mg/g Cr with levels significantly higher in females. When considering chronic kidney disease (CKD) stages we observed a progressive decrease in urinary osmolality and in urinary citrate, calcium and uric acid elimination. Low levels of citrate (&amp;lt;300 mg/g Cr) were present in 40% in CKD-1 stage, in 69.7% in CKD-2 stage, 92% in CKD-3 stage and 100% in CKD-4 + 5 stages. Urinary citrate was correlated with serum creatinine (r= -0.66, p&amp;lt;0.001) and eGFR (r= 0.56, p&amp;lt;0.001). Urinary citrate significantly correlated with urinary calcium but correlation with urinary uric acid was weaker. We did not find any correlation with serum bicarbonate. Using multiple lineal regression analysis we found as predictors of urinary citrate to glomerular filtration rate, female gender and urinary calcium levels. In a subgroup of patients we measured total kidney volume and we found an inverse correlation with urinary citrate levels that dissappeared when it was corrected with glomerular filtration rate. We did not also find a relationship between urinary elimination of calcium or uric acid and TKV after adjusting with eGFR. Conclusion Urinary citrate is very frequently reduced in ADPKD patients being present from very early CKD stages. Their levels are inversely correlated with glomerular filtration rate and directly with urinary calcium excretion. We did not found a relathionship with serum bicarbonate. We think that it would be interesting to study urinary citrate in other nephropathies and verify if it could be a marker of covert metabolic acidosis.

Efficacy of L-Carnitine on 24-Hour Urine Metabolites in Patients with a History of Recurrent Stone Formation

Background: Kidney stones are one of the most common health problems in developed countries. A significant number of these populations experience recurrent stone formation with pain, urinary tract infection, or decreased parenchyma and renal function. Objectives: Accordingly, the aim of this study was to evaluate the effect of L-carnitine on 24-hour urine metabolites in patients with a history of recurrent stone formation. Methods: This study was conducted on patients with recurrent stone formation. After the study samples were selected, they were provided with the necessary information about the study and their medical status. Demographic data and 24-hour urine indicators (including calcium, oxalate, uric acid, and citrate) were recorded before treatment. Patients were followed up for two weeks with no drug treatment and a regular food diet. At the end of the two weeks, 24-hour urine samples were collected and evaluated for calcium, oxalate, uric acid, and citrate. Patients were then treated with L-carnitine for eight weeks, with a dose of 1 gr daily. At the end of the eighth week, 24-hour urine samples were collected and evaluated for calcium, oxalate, uric acid, and citrate. Finally, the data obtained from this study were statistically analyzed. Results: 34 individuals with a mean age of 39.5 ± 11.8 years participated in the study.11 patients (32.3%) were female, and 23 patients (67.7%) were male. The mean weight of the patients was 69.7 ± 10.6 kg of the mean size of the renal stones before and after treatment was 3.8 ± 3.1 and 3.6 ± 3.2 mm, respectively (P = 0.92). Moreover, the mean levels of uric acid, oxalate, citrate, and calcium before treatment were 748.3 ± 368.8, 28.9 ± 15.0, 945.5 ± 751.3, and 172.2 ± 116.1, respectively. The mean values of these urinary metabolites after treatment were 482.0 ± 266.7, 23.0 ± 13.1, 837.6 ± 609.9, and 134.8 ± 103.0, in the same order. A statistically significant decrease in the levels of uric acid, oxalate, and citrate is thus observed (P ≤ 0.05). Although calcium levels decreased after treatment, this reduction was not statistically significant (P = 0.08). Conclusions: Treatment with L-carnitine, although did not result in a smaller size of the stones, decreased the urinary metabolite levels. This reduction may be effective in reducing the recurrence of stone formation.

The Hepatic Plasma Membrane Citrate Transporter NaCT (SLC13A5) as a Molecular Target for Metformin

Metformin is the first-line treatment for type 2 diabetes. Inhibition of hepatic gluconeogenesis is the primary contributor to its anti-diabetic effect. Metformin inhibits complex I and α-glycerophosphate shuttle, and the resultant increase in cytoplasmic NADH/NAD+ ratio diverts glucose precursors away from gluconeogenesis. These actions depend on metformin-mediated activation of AMP kinase (AMPK). Here we report on a hitherto unknown mechanism. Metformin inhibits the expression of the plasma membrane citrate transporter NaCT in HepG2 cells and decreases cellular levels of citrate. 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR), an AMPK activator, elicits a similar effect. The process involves a decrease in maximal velocity with no change in substrate affinity. The decrease in NaCT expression is associated with decreased mRNA levels. AMPK inhibits mTOR, and the mTOR inhibitor rapamycin also decreases NaCT expression. The transcription factor downstream of AMPK that is relevant to cAMP signaling is CREB; decreased levels of phospho-CREB seem to mediate the observed effects of metformin on NaCT. Citrate is known to suppress glycolysis by inhibiting phosphofructokinase-1 and activate gluconeogenesis by stimulating fructose-1,6-bisphophatase; therefore, the decrease in cellular levels of citrate would stimulate glycolysis and inhibit gluconeogenesis. These studies uncover a novel mechanism for the anti-diabetic actions of metformin.

Comparative Blood and Urine Metabolomics Analysis of Healthy Elderly and Young Male Singaporeans.

Comparative metabolomics analysis of biofluids could provide information about the metabolic alterations in aging. To investigate the signature of multiple metabolic profiles associated with aging in an Asian population, we performed a pilot study in healthy Singaporeans, including 33 elderly and 33 young males. Fasting whole bloods were analyzed by routine hematology; the serum and urine metabolome profiles were obtained using NMR-based nontargeted metabolomics analysis and targeted lipoprotein analysis. Among the 90 identified compounds in serum and urine samples, 32 were significantly different between the two groups. The most obvious age-related metabolic signatures include decreased serum levels of albumin lysyl and essential amino acids and derivatives but increased levels of N-acetyl glycoproteins and several lipids and elevated urine levels of trimethylamine N-oxide, scyllo-inositol, citrate, and ascorbic acid but decreased levels of several amino acids, acetate, etc. Among 112 lipoprotein subfractions, 65 were elevated, and 2 were lower in the elderly group. These significantly age-varying metabolites, especially in the amino acid and fatty acid metabolism pathways, suggest that the regulation of these pathways contributes to the aging process in Chinese Singaporeans. Further multiomics studies including the gut microbiome and intervention studies in a larger cohort are needed to elucidate the possible mechanisms in the aging process.

Protective Role of Melatonin Against Postmenopausal Bone Loss via Enhancement of Citrate Secretion From Osteoblasts.

A negative correlation exists between the severity of osteoporosis and citrate levels in bone. Our previous research found that melatonin can significantly improve bone mass in mice with osteoporosis, but the underlying mechanism involving citrate remains unknown. Herein, we demonstrated that melatonin increased bone volume and citrate levels in ovariectomized osteoporosis mice. Melatonin increased citrate and mineralized nodules in osteoblasts induced from primary mouse bone marrow mesenchymal stem cells in vitro. ZIP-1 knockdown and overexpression confirmed that melatonin specifically upregulated ZIP-1 to rescue citrate levels and bone mass. In general, we verified that melatonin can improve bone mass by enhancing matrix mineralization, which is highly related to increased citrate secretion from osteoblasts, and that ZIP-1 is the target of melatonin. These findings reveal another role of melatonin in regulating bone remodeling and provide a research base for its possible application in the treatment of clinical osteoporosis in the future.

1H HRMAS-NMR based metabolic fingerprints for discrimination of cheeses based on sensory qualities.

In this study, the 1H HRMAS-NMR (High-resolution Magic Angle Spinning-Nuclear Magnetic Resonance) spectra of 52 cheese samples obtained from the South Korean dairy farms were evaluated for their metabolic profiling and intensities associating with the sensory qualities. The NMR profiles displayed a broad range of compounds comprising amino acids, carbohydrates, organic acids, and phospholipids. Afterwards, the cheese samples were categorized into three groups (more likeness - G1, moderate likeness - G2, less likeness - G3), in relating to their sensory scores. The NMR data of the samples were later investigated through multivariate statistical tools to define the variations in metabolic fingerprints of every cheese sample and their intensities hailing in individual sensory groups. The unsupervised PCA employing all cheese samples unveiled the uniqueness in metabolite profiles of the brown and cheddar type cheeses (outliers). Moreover, Gouda and other types of cheeses displayed samples positioning in respective of their metabolite profiles. The pairwise comparison of sensory groups in the supervised models perceived better separation in OPLS-DA than PLS-DA. The corresponding VIP (PLS-DA) and loading (OPLS-DA) plots revealed amino acids and organic acids (lactate, citrate) as significant variables. The discrimination of G 1 Gouda type of cheeses against G 2 and G 3 was highly associated with their citrate levels. Further investigation using heatmaps displayed clear differentiation between each sensory group in terms of the levels of amino acids, lactate, citrate, phospholipids, and glycerol, conveying these variations are likely due to proteolytic and metabolic processes in cheese ripening. This study concluded that 1H HRMAS-NMR metabolite profile of the Korean cheeses is consistence with their sensory qualities. Further, the candidate metabolites identified in this study confers their potential application as biomarkers in cheese industries for faster and effective validation of sensory characteristics.

Citrate Mediates Crosstalk between Mitochondria and the Nucleus to Promote Human Mesenchymal Stem Cell In Vitro Osteogenesis.

Citrate, generated in the mitochondria, is a key metabolite that might link metabolism with signaling, chromatin structure and transcription to orchestrate mesenchymal stem cells (MSCs) fate determination. Based on a detailed morphological analysis of 3D reconstruction of mitochondria and nuclei in single cells, we identified contact sites between these organelles that drastically increase in volume and number during the early stage of mesenchymal stem cell differentiation. These contact sites create a microdomain that facilitates exchange of signals from mitochondria to the nucleus. Interestingly, we found that the citrate derived from mitochondria is necessary for osteogenic lineage determination. Indeed, inhibition of the citrate transporter system dramatically affected osteogenesis, reduced citrate levels that could be converted in α-ketoglutarate, and consequently affected epigenetic marker H3K9me3 associated with the osteogenesis differentiation process. These findings highlight that mitochondrial metabolites play key regulatory roles in the MSCs differentiation process. Further in-depth investigation is needed to provide novel therapeutic strategies in the field of regenerative medicine.

Nuclear magnetic resonance-based targeted profiling of urinary acetate and citrate following cyclophosphamide therapy in patients with lupus nephritis.

Metabolomics, the study of global alterations in small metabolites, is a useful tool to look for novel biomarkers. Recently, we reported a reprogramming of the serum metabolomic profile by nuclear magnetic resonance (NMR) spectroscopy following treatment in lupus nephritis (LN). This study aimed to compare the urine excretory levels of citrate and acetate in patients with biopsy-proven LN before and six months after cyclophosphamide induction therapy and to evaluate their correlation with the Systemic Lupus Erythematosus Disease Activity Index 2K (SLEDAI 2K) and renal SLEDAI. Urine obtained from LN patients (N = 18, 16 female) at diagnosis and six months following induction therapy with cyclophosphamide and healthy controls (HC; N = 18, median age = 35 years, all female) were stored at -80°C. Metabolomic profiling was done using high resolution 800 MHz 1D 1H NMR spectroscopy. The urinary ratio of metabolites was calculated as (metabolite×1000)/creatinine. Disease activity was measured using the SLEDAI. Metabolomic profiles were compared between groups and correlated with clinical parameters. Compared to HC, LN patients had significantly lower median urinary citrate/creatinine levels (LN = 18.26, range 12.80-27.62; HC = 107.7, range 65.39-138.4; p < 0.0001) which significantly increased after six months of cyclophosphamide treatment (51.05, range 11.51-170.2; p = 0.03). LN patients also differed from HC by having a higher mean urinary acetate/creatinine ratio (LN = 17.44, range 11.6-32.7; HC = 9.61, range 7.97-13.71; p = 0.054) with a non-significant fall in values after six months of treatment. The Area under curve for differentiating LN from HC for urinary citrate was 0.9136, and urinary acetate was 0.6883. The urinary acetate levels correlated with SLEDAI (r = 0.337, p = 0.048). Urinary citrate levels correlated positively with C3 (r = 0.362, p = 0.03) and negatively with urine protein/creatinine (r = -0.346, p = 0.039). Urinary citrate, which reflects dampened aerobic glycolysis and oxidative phosphorylation, improved significantly and is a potential non-invasive biomarker for diagnosis and monitoring treatment response in LN.

Cold storage reveals distinct metabolic perturbations in processing and non-processing cultivars of potato (Solanum tuberosum L.)

Cold-induced sweetening (CIS) causes considerable losses to the potato processing industry wherein the selection of potato genotypes using biochemical information has found to be advantageous. Here, 1H NMR spectroscopy was performed to identify metabolic perturbations from tubers of five potato cultivars (Atlantic, Frito Lay-1533, Kufri Jyoti, Kufri Pukhraj, and PU1) differing in their CIS ability and processing characteristics at harvest and after cold storage (4 °C). Thirty-nine water-soluble metabolites were detected wherein significantly affected metabolites after cold storage were categorized into sugars, sugar alcohols, amino acids, and organic acids. Multivariate statistical analysis indicated significant differences in the metabolic profiles among the potato cultivars. Pathway enrichment analysis revealed that carbohydrates, amino acids, and organic acids are the key players in CIS. Interestingly, one of the processing cultivars, FL-1533, exhibited a unique combination of metabolites represented by low levels of glucose, fructose, and asparagine accompanied by high citrate levels. Conversely, non-processing cultivars (Kufri Pukhraj and Kufri Jyoti) showed elevated glucose, fructose, and malate levels. Our results indicate that metabolites such as glucose, fructose, sucrose, asparagine, glutamine, citrate, malate, proline, 4-aminobutyrate can be potentially utilized for the prediction, selection, and development of potato cultivars for long-term storage, nutritional, as well as processing attributes.

Effects of GABA and Vigabatrin on the Germination of Chinese Chestnut Recalcitrant Seeds and Its Implications for Seed Dormancy and Storage.

Recalcitrant chestnut seeds are rich in γ-aminobutyric acid (GABA), which negatively regulates adventitious root development by altering carbon/nitrogen metabolism. However, little is known regarding the role of this metabolite in chestnut seeds. In this study, we investigated the effects of GABA changes on the germination of chestnut seeds treated with exogenous GABA and vigabatrin (VGB, which inhibits GABA degradation). Both treatments significantly inhibited seed germination and primary root growth and resulted in the considerable accumulation of H2O2, but the endogenous GABA content decreased before germination at 48 h. Soluble sugar levels increased before germination, but subsequently decreased, whereas starch contents were relatively unchanged. Changes to organic acids were observed at 120 h after sowing, including a decrease and increase in citrate and malate levels, respectively. Similarly, soluble protein contents increased at 120 h, but the abundance of most free amino acids decreased at 48 h. Moreover, the total amino acid levels increased only in response to VGB at 0 h. Accordingly, GABA and VGB altered the balance of carbon and nitrogen metabolism, thereby inhibiting chestnut seed germination. These results suggested that changes to GABA levels in chestnut seeds might prevent seed germination. The study data may also help clarify the dormancy and storage of chestnut seeds, as well as other recalcitrant seeds.

Efficacy of Herbmed Plus in urolithic rats: An experimental study

BackgroundIn Ayurveda, several herbs and formulations are available for the treatment of Urolithiasis. However, they are not systematically evaluated for their safety, efficacy, indication and limitations. Herbmed Plus is one such herbal formulation that has been known for the management of urinary tract disorders. An attempt has been made to evaluate its efficacy on Urolithiasis. ObjectiveTo evaluate the efficacy and safety of Herbmed Plus in urolithic rats. Materials and methodsA total of 60 Wistar albino rats were used for this study. The male and female rats were divided into five groups: disease control, test (dose 90 mg/kg), standard I (Cystone), standard II (Alkaston insta) and normal control (six in each group). Urolithiasis was induced using ethylene glycol 0.75% in drinking water for 28 days. The rats with urinary oxalate crystals were dosed with oral test or standard treatments for 28 days. ResultsAll the animals appeared normal and showed no clinical signs of toxicity. None of the groups reported mortality or adverse effect on body weight and food consumption. The treatment with test drug showed improvement in the SGPT level and urine output (5.4 vs 3.47 mL/24 h). A drastic reduction in number of crystals were observed in male 0.5 vs 22 and female rats 0 vs 22.7 in test and disease group. The kidney lactate dehydrogenase, alkaline phosphatase, urinary phosphorus and calcium oxalate level decreased in the test and standard drug groups as compared to disease groups. Microscopy of the urine samples showed reduction in the number of crystals after treatment compared to the urolithic group. Increase in citrate levels in urine in all the treatment groups indicated anti-urolithiatic activity. The test group showed a 69.70% recovery in males and 47.57% recovery in female rats compared to the disease control group. ConclusionHerbmed Plus showed a significant reduction in oxalate synthesizing enzymes suggesting anti-urolithiatic activity and anti-inflammatory and regenerative property in cellular injury caused by crystal deposits.

Urinary Citrate: A Potential Biomarker for IgA Nephropathy

Background: Citrate is filtered by the glomeruli and reabsorbed in tubular cells in kidney. Through this study, we have tried to explore citrate as a diagnostic tool for IgA nephropathy. Methods: We recruited 35 IgA nephropathy (IgAN) patients and 15 healthy controls (HC). 30 ml urine sample collected from each study participant. Solid phase extraction method used for urine purification. Liquid chromatography attached with mass spectrometry (LC–MS/MS) used for the citrate concentration determination. Logistic regression method used for diagnostic model prediction. Findings: Urinary citrate level was higher in IgAN patients by more than two and half times in comparison to HC. We made logistic regression model with citrate, urine protein, estimated glomerular filtration rate (eGFR), urine pH, systolic and diastolic blood pressure as variables. Citrate with urine protein was found to be the best fit statistical model with area under curve 0.77 and sensitivity and specificity more than 0.70 and 0.80, respectively. Applications: Urinary citrate with urine protein can be used for the early prediction of IgAN. Keywords: IgAN, Citrate, Urine Protein, Kidney Stone.

Ruolo del citrato nel metabolismo osseo

Citrate is an organic compound involved in tricarboxylic acid cycle, regulation of acid-base balance, lipid metabolism and bone formation. The 90% of body citrate is deposited in bone tissue and is released with calcium ions during bone resorption; therefore, bone resorption contributes to maintain normal plasma levels of citrate together with kidney excretion. The parallel release of citrate and calcium from bones decreases the possibility of calcium-phosphate precipitation in soft tissues, as citrate can bind calcium ions in organic fluids. Citrate may also take part to the bone formation as it sustains the correct mineralization of bone organic matrix: its molecule binds calcium ions at the surface of hydroxyapatite nanocrystals and maintains the correct spatial disposition of nanocrystals, thus, stabilizing the structure of bone lamellae and sustaining biomechanical characteristics of bone tissue. Multiple studies observed that citrate administration significantly increased areal and volumetric bone mineral density at different locations of 1-2% per year and improved bone resorption markers as well. Therefore, it has been hypothesised a therapeutic role of citrate in osteoporosis; however, this role has to be better clarified to understand its real anti-fracture effect.

Urinary NMR Profiling in Pediatric Acute Kidney Injury-A Pilot Study.

Acute kidney injury (AKI) in critically ill children and adults is associated with significant short- and long-term morbidity and mortality. As serum creatinine- and urine output-based definitions of AKI have relevant limitations, there is a persistent need for better diagnostics of AKI. Nuclear magnetic resonance (NMR) spectroscopy allows for analysis of metabolic profiles without extensive sample manipulations. In the study reported here, we examined the diagnostic accuracy of NMR urine metabolite patterns for the diagnosis of neonatal and pediatric AKI according to the Kidney Disease: Improving Global Outcomes (KDIGO) definition. A cohort of 65 neonatal and pediatric patients (0–18 years) with established AKI of heterogeneous etiology was compared to both a group of apparently healthy children (n = 53) and a group of critically ill children without AKI (n = 31). Multivariate analysis identified a panel of four metabolites that allowed diagnosis of AKI with an area under the receiver operating characteristics curve (AUC-ROC) of 0.95 (95% confidence interval 0.86–1.00). Especially urinary citrate levels were significantly reduced whereas leucine and valine levels were elevated. Metabolomic differentiation of AKI causes appeared promising but these results need to be validated in larger studies. In conclusion, this study shows that NMR spectroscopy yields high diagnostic accuracy for AKI in pediatric patients.

Plasma Krebs Cycle Intermediates in Nonalcoholic Fatty Liver Disease.

Nonalcoholic liver disease (NAFLD) is manifested with a wide spectrum of clinical symptoms and is closely associated with the metabolic syndrome, inflammation, and mitochondrial dysfunction. Although the mechanism of mitochondrial dysfunction in NAFLD is still not fully elucidated, multiple studies have demonstrated evidence of molecular, biochemical, and biophysical mitochondrial abnormalities in NAFLD. Given the association between NAFLD and mitochondrial dysfunction, the aim of this study is to analyze circulating levels of Krebs cycle intermediates in a cohort of NAFLD-affected individuals and matching healthy controls and to correlate our findings with the liver function metrics. Standard serum biochemistry and Krebs cycle intermediates were analyzed in NAFLD (n = 22) and matched control (n = 67) cohorts. Circulating levels of isocitrate and citrate were significantly (p < 0.05) elevated in the NAFLD cohort of patients. The area under the curve (AUROC) for these two metabolites exhibited a moderate clinical utility. Correlations between plasma Krebs cycle intermediates and standard clinical plasma metrics were explored by Pearson’s correlation coefficient. The data obtained for plasma Krebs cycle intermediates suggest pathophysiological insights that link mitochondrial dysfunction with NAFLD. Our findings reveal that plasma isocitrate and citrate can discriminate between normal and NAFLD cohorts and can be utilized as noninvasive markers of mitochondrial dysfunction in NAFLD. Future studies with large populations at different NAFLD stages are warranted.

Application of Stable Isotope Tracing to Elucidate Metabolic Dynamics During Yarrowia lipolytica α-Ionone Fermentation.

SummaryTargeted metabolite analysis in combination with 13C-tracing is a convenient strategy to determine pathway activity in biological systems; however, metabolite analysis is limited by challenges in separating and detecting pathway intermediates with current chromatographic methods. Here, a hydrophilic interaction chromatography tandem mass spectrometry approach was developed for improved metabolite separation, isotopologue analysis, and quantification. The physiological responses of a Yarrowia lipolytica strain engineered to produce ∼400 mg/L α-ionone and temporal changes in metabolism were quantified (e.g., mevalonate secretion, then uptake) indicating bottleneck shifts in the engineered pathway over the course of fermentation. Dynamic labeling results indicated limited tricarboxylic acid cycle label incorporation and, combined with a measurable ATP shortage during the high ionone production phase, suggested that electron transport and oxidative phosphorylation may limit energy supply and strain performance. The results provide insights into terpenoid pathway metabolic dynamics of non-model yeasts and offer guidelines for sensor development and modular engineering.