Sergei Likhodi

ABSTRACT. Objective. To investigate the relationship between plasma and synovial fluid (SF) metabolite concentrations in patients with osteoarthritis (OA). Methods. Blood plasma and SF samples were collected from patients with primary knee OA undergoing total knee arthroplasty. Metabolic profiling was performed by electrospray ionization tandem mass spectrometry using the AbsoluteIDQ kit. The profiling yielded 168 metabolite concentrations. Correlation analysis between SF and plasma metabolite concentrations was done on absolute concentrations as well as metabolite concentration ratios using Spearman's rank correlation (r) method. Results. A total of 69 patients with knee OA were included, 30 men and 39 women, with an average age of 66 ± 8 years. For the absolute metabolite concentrations, the average r was 0.23 ± 0.13. Only 8 out of 168 metabolite concentrations had a r ≥ 0.45, with a p value ≤ 2.98 × 10 -4 , statistically significant after correcting multiple testing with the...

Immunoassays are laboratory technologies used for cost-effective and sensitive assessment of many different analytes. These analytes account for about 25% of the tests done at large regional laboratories and include tests ranging from those for specific drugs like Dilantin and Digoxin; proteins like PSA, Troponin, and Ferritin; vitamins like Vitamin B12 and Folate; and hormones like TSH, free T4, Estradiol, Progesterone, and Testosterone, and many others. Recognition of the analyte by the assays occurs through complex interaction of antibodies within the assay reagent with certain parts of the analyte molecule.

ackground: The ketogenic diet is used to treat epilepsy refractory to anticonvulsant medication. Individuals with epilepsy often have ehavioral problems and deficits in attention and cognitive functioning. The ketogenic diet has been found to effect improvements in hese domains. It has also been suggested that the ketogenic diet may act as a mood stabilizer. ethods: The present research used the Porsolt test, an animal model of depression, to determine whether the ketogenic diet has ntidepressant properties. Porsolt test scores of rats on the ketogenic diet were compared with those of rats on a control diet. esults: The rats on the ketogenic diet spent less time immobile, suggesting that rats on the ketogenic diet, like rats treated with ntidepressants, are less likely to exhibit “behavioral despair.” onclusions: It is concluded that the ketogenic diet may have antidepressant properties.

In a series of sequential studies from 2003 to 2007, we examined the quality of life in children with epilepsy, partial and generalized, on and off AEDs. All children came from a community-based practice referred to a paediatric neurologist (PAH) and were followed using standardized problem-oriented medical records. EEGs were all performed on Harmonie , from Stellate , Montreal, QC with electrodes in 10–20 positions, EOG, chin EMG and ECG. Two methods of assessing QOLIE used the Cramer (2002) and the Ronen (2005) scales, both validated and applied consistently. Behavioral measures used the SNAP IV 26-item questionnaire of Swan (1975). Statistical tests applied included t-tests, Chi-square. In four serial studies over five years, in 80 children, the major finding was a significant improvement in QOLIE among seizurefree children compared to seizure-prone, with better behavioral outcome: in attention, hyperactive and oppositional subscales in SNAP IV test. No significant differences we...

Abstract Objectives: The objective of this study was the investigation of age- and sex-associations in a set of blood plasma metabolites in healthy male and female subjects. Methods: A comparison study design with male and female subjects of various ages was used. Metabolic profiling was performed using electrospray ionization tandem mass spectrometry that yielded 186 metabolite concentrations for each study participant. The key age-related metabolites were identified using an integrative analysis of absolute concentrations, metabolite ratios and the differential correlation of pairwise metabolite concentrations. All of the age-associated metabolites were adjusted prior to the analysis to account for differences in Body Mass Index (BMI). Results: A total of 236 plasma samples from 140 female and 96 male subjects aged 20 to 82 years-old were collected and analyzed in the study. 13 and 14 age-associated metabolites (|r| > 0.33 and p < 6.6×10−5), 438 and 337 age-associated metabolite ratios (|r| > 0.37 and p < 3.5×10−6), and 5 and 10 core metabolites were discovered in the female and male groups, respectively. 80% of the metabolites displaying associations with age belonged to sphingolipids and phosphatidylcholines, and the two sexes shared less than 50% of the age-associated metabolites. Conclusion: The study found that changes in metabolite concentrations, metabolite ratios and differential correlations were age and sex-specific. Graphical Abstract

Objectives To determine whether pre-existing nephropathy impacts urinary KIM-1 levels, urinary KIM-1 were measured in patients with normal kidney filtration function but either with or without proteinuria. The reference intervals of urinary KIM-1 in adults with normal kidney filtration function but without urine proteinuria were established. Design and methods 188 urine samples were obtained from adults with normal kidney filtration. 83 of the 188 showed negative urine protein, erythrocytes and leucocytes were used as normal controls. The remaining 105 samples showed at least one abnormal result suggesting possible pre-existing nephropathy. Urinary KIM-1 concentrations were measured using an enzyme-linked immunosorbent assay. Urinary KIM-1 was normalized with urine creatinine concentration. The reference interval for urinary KIM-1 was determined by non-parametric methodology on 147 individuals. Results The results showed significantly increased urinary KIM-1 concentration in protein positive (protein +, erythrocyte +/−, leucocyte+/-) samples compared to controls (protein-, erythrocyte -, leucocyte -). Urinary KIM-1 concentrations were significantly higher when proteinuria was at trace concentration (0.25 g/L) and correlated with the severity of proteinuria. The creatinine normalized urinary KIM-1 was significantly higher when urine protein was 1 + to 3+ (0.75–5 g/L). The reference interval for urinary KIM-1 was 0.00 (90%CI: 0-0) to 4.19 (90%CI: 3.11–5.62) μg/L, and for creatinine normalized urinary KIM-1 0.00 (90%CI: 0-0) to 0.58 (90%CI: 0.44–0.74) μg/mmol. Conclusions Baseline urinary KIM-1 concentrations were increased when there was detectable urine protein and correlated with its severity. The urinary KIM-1 concentrations should be interpreted with consideration of urine protein levels in individual patients.

Background Accumulating evidence suggests an independent association between osteoarthritis (OA) and type 2 diabetes mellitus (DM). Our recent work [Zhang, et al. Metabolomics, 2015] found phosphatidylcholine acyl-alkyl C34:3 (PC ae C34:3) and phosphatidylcholine acyl-alkyl C36:3 (PC ae C36:3) were associated with both OA and DM. Both synovial and plasma concentrations of these two metabolites were reduced in knee OA and DM patients, and OA patients with DM had lowest concentration of these two metabolites, suggesting the altered unsaturated phosphatidylcholine metabolism may be responsible for the association between OA and DM. Objectives We hypothesized hyperglycemia-related production of advanced glycation end-products (AGEs) was involved in the altered phosphatidylcholine metabolism in OA patients and tested this hypothesis in the current study. Methods Synovial fluid and plasma samples were collected from OA patients with and without DM. Hyperglycemia-related AGEs including methylglyoxal (MG) and methylglyoxal-derived hydroimidazolone (MG-H1) levels were measured in both synovial fluid and plasma samples using UPLC/MS method. The correlation between MG, MG-H1, and PC ae C34:3 and PC ae C36:3 were examined. Results 84 knee OA patients, including 46 with DM and 38 without DM, were included in the study. We did not find a significant difference in plasma MG-H1 concentration between OA with and without DM. However, we found that log transformed synovial concentrations of MG-H1 in the groups of OA with diabetes were 2.56±0.27 ng/ml which was significantly higher than that in the group of OA without diabetes (2.39 ±0.25 ng/ml, P=0.012). Similarly, synovial concentration of MG was 2.05±0.11 ng/ml in the group of OA with diabetes which was significantly higher than 1.99±0.11 ng/ml in the group of OA without diabetes (P=0.046). The significance remained after adjusting the age, BMI and sex. The correlation between MG-H1 and PC ae C34:3, MG-H1 and PC ae C36:3, MG and PC aeC34:3, and MG and PC ae C36:3 were -0.15, -0.32, -0.23 and -0.06, respectively. Conclusions We demonstrated that both MG-H1 and MG concentrations in synovial fluid were elevated in OA patients with DM and associated with the levels of PC ae C34:3 and PC ae C36:3, suggesting that hyperglycemia-related AGEs may be responsible for the altered phosphotidylcholine metabolism in OA. References Weidong Zhang, Guang Sun, Sergei Likhodii, Erfan Aref-Eshghi, Patricia E. Harper, Edward Randell, Roger Green, Glynn Martin, Andrew Furey, Proton Rahman, Guangju Zhai. Metabolomic analysis of human synovial fluid and plasma reveals that phosphatidylcholine metabolism is associated with both osteoarthritis and diabetes mellitus. Metabolomics (2016) 12:24. DOI 10.1007/s11306–015–0937-x Acknowledgement We thank all the study participants who made this study possible, and all the staff who helped us in the collection of samples. The study was funded by Canadian Institutes of Health Research (CIHR), Newfoundland & Labrador RDC, and Memorial University. Disclosure of Interest None declared

Background: The mechanism of action of the ketogenic diet, a therapy for refractory epilepsy, is unknown. Our hypothesis is that acetone, one of three ketones elevated by the ketogenic diet, is directly responsible for the diet's anticonvulsant effects. This study examined the basic concepts of this hypothesis. Material/methods: Rats were acutely injected with acetone intraperitoneally at doses of 1 or 10 mmol/kg, or received acetone chronically in drinking water (1% v/v) for 10 days before being injected with a 1 mmol/kg dose of acetone. Controls consumed regular water and were injected with vehicle. A pentylenetetrazole seizure test was administered 15 min after the injections. Following the test, acetone was measured in the cerebrospinal fluid. Results: A 10 mmol/kg injection of acetone suppressed seizures in 60% of rats (P<0.05). A chronic administration of acetone followed by a 1 mmol/kg injection suppressed seizures in 47% of rats (P<0.05). The acetone concentrations in these rats were 10.3I2.3 and 1.0I0.2 mmol/L, respectively. The effect of the acute 1 mmol/kg injection (without acetone pretreatment) was not statistically significant. This dose elevated acetone to 1.1I0.1 mmol/L in the cerebrospinal fluid. Conclusions: Our findings suggest that acetone is an anticonvulsant and that chronic administration may enhance its action. Linking acetone to the effects of the ketogenic diet requires further research. In particular, it will be important to confirm that the ketogenic diet generates relevant concentrations of acetone.

To identify novel biomarker(s) for predicting advanced knee OA. Study participants were derived from the Newfoundland Osteoarthritis Study and the Tasmania Older Adult Cohort Study. All knee OA cases were patients who underwent total knee replacement (TKR) due to primary OA. Metabolic profiling was performed on fasting plasma. Four thousand and eighteen plasma metabolite ratios that were highly correlated with that in SF in our previous study were generated as surrogates for joint metabolism. The discovery cohort included 64 TKR cases and 45 controls and the replication cohorts included a cross-sectional cohort of 72 TKR cases and 76 controls and a longitudinal cohort of 158 subjects, of whom 36 underwent TKR during the 10-year follow-up period. We confirmed the previously reported association of the branched chain amino acids to histidine ratio with advanced knee OA (P = 9.3 × 10(-7)) and identified a novel metabolic marker-the lysophosphatidylcholines (lysoPCs) to phosphatidylchol...

In the early 1900s, medical practitioners recognized fasting as an effective method for controlling seizures (1,2). The mechanism by which fasting suppressed seizures was initially explained as an alleviation of “intestinal intoxication,” which in turn was thought to be the cause of epilepsy (1).

Arachidonic acid (AA; 20:4n-6) is one of the principal components of the phosphoglycerides in neural cell membranes. During the critical period of postnatal development in mammals, AA is supplied preformed, directly from the milk or derived from precursor fatty acids such as gamma-linolenic acid (GLA; 18:3n-6). In this study, 13C-NMR spectroscopy was applied to investigate the incorporation of [1-(13)C]AA and [3-(13)C]GLA into liver and brain lipids of 7-15-day-old rats. The main objective was to establish the importance of dietary GLA for tissue AA accretion relative to the contribution from preformed dietary AA. [1-(13)C]AA and [3-(13)C]GLA were injected into the stomach of 7-day-old rats as a mixture. 13C-NMR spectroscopy of lipid extracts revealed incorporation of [1-(13)C]AA and [5-(13)C]AA (the latter derived from metabolism of the injected [3-(13)C]GLA) into phosphoglycerides and triacylglycerols. Preformed AA was 10 (liver)-17 (brain) times more efficient in contributing to tissue AA than AA derived from precursor GLA. In separate experiments, NMR spectroscopy was used to assess uptake of [1-(13)C]AA directly in living rats and intact organs. Results showed that intact liver and brain contain an appreciable amount of NMR-detectable lipids. The in vivo/in vitro information obtained from organs provided details on the mobility and turnover of tissue lipids.

AbstractThis study was to investigate how OA patients with metabolic syndrome (MetS) are different metabolically from OA patients without MetS components and healthy individuals. A two-stage case–control study design was utilized. Synovial fluid (SF) and plasma samples were collected from patients undergoing total knee joint replacement due to primary OA and healthy controls (only plasma) and metabolically profiled using UPLC-MS coupled with assay kit which measures 186 metabolites. Orthogonal projection to latent structure-discriminant analysis and linear regression were used to identify metabolic markers for discriminating OA patients with MetS components from those without and healthy individuals. 54 paired SF and plasma samples from knee OA patients and 30 plasma samples from healthy controls were included in the discovery stage, and 143 plasma samples (72 from knee OA patients and 71 from the age, sex, and BMI matched controls) were included in the validation stage. OA patients with MetS can be clearly discriminated from OA patients without MetS based on the metabolite profiles of both SF and plasma and the separation appeared to be driven by type 2 diabetes but not obesity, hypertension, or dyslipidemia. When compared with OA patients with diabetes, OA without diabetes, and healthy controls, phosphatidylcholine acyl-alkyl C34:3 (PC ae C34:3) and phosphatidylcholine acyl-alkyl C36:3 (PC ae C36:3) were identified and confirmed to be associated with the concurrence of OA and diabetes (all p &lt; 0.003). The study demonstrated that altered phosphatidylcholine metabolism was associated with both OA and diabetes mellitus.

To identify novel biomarker(s) for knee osteoarthritis (OA) using a metabolomics approach. We utilized a two-stage case-control study design. Plasma samples were collected from knee OA patients and healthy controls after 8-hour fasting and metabolically profiled using a targeted metabolomics assay kit. Linear regression was used to identify novel metabolic markers for OA. Receiver operating characteristic (ROC) analysis was used to examine diagnostic values. Gene expression analysis was performed on human cartilage to explore the potential mechanism for the novel OA marker(s). 64 knee OA patients and 45 controls were included in the discovery stage and 72 knee OA patients and 76 age and sex matched controls were included in the validation stage. We identified and confirmed six metabolites that were significantly associated with knee OA, of which arginine was the most significant metabolite (p &lt; 3.5×10(-13)) with knee OA patients having on average 69 μM lower than that in controls...

To investigate the relationship between plasma and synovial fluid (SF) metabolite concentrations in patients with osteoarthritis (OA). Blood plasma and SF samples were collected from patients with primary knee OA undergoing total knee arthroplasty. Metabolic profiling was performed by electrospray ionization tandem mass spectrometry using the AbsoluteIDQ kit. The profiling yielded 168 metabolite concentrations. Correlation analysis between SF and plasma metabolite concentrations was done on absolute concentrations as well as metabolite concentration ratios using Spearman&#39;s rank correlation (ρ) method. A total of 69 patients with knee OA were included, 30 men and 39 women, with an average age of 66 ± 8 years. For the absolute metabolite concentrations, the average ρ was 0.23 ± 0.13. Only 8 out of 168 metabolite concentrations had a ρ ≥ 0.45, with a p value ≤ 2.98 × 10(-4), statistically significant after correcting multiple testing with the Bonferroni method. For the metabolite r...

To identify metabolic markers that can classify patients with osteoarthritis (OA) into subgroups. A case-only study design was utilised. Patients were recruited from those who underwent total knee or hip replacement surgery due to primary OA between November 2011 and December 2013 in St. Clare&#39;s Mercy Hospital and Health Science Centre General Hospital in St. John&#39;s, capital of Newfoundland and Labrador (NL), Canada. 38 men and 42 women were included in the study. The mean age was 65.2±8.7 years. Synovial fluid samples were collected at the time of their joint surgeries. Metabolic profiling was performed on the synovial fluid samples by the targeted metabolomics approach, and various analytic methods were utilised to identify metabolic markers for classifying subgroups of patients with OA. Potential confounders such as age, sex, body mass index (BMI) and comorbidities were considered in the analysis. Two distinct patient groups, A and B, were clearly identified in the 80 pat...

The ketogenic diet is a high-fat, low-carbohydrate diet used to treat drug-resistant seizures, especially in children. A number of possible mechanisms of action have been proposed to explain the anticonvulsant effects of the diet. Four of these hypothetical mechanisms are discussed in the present article: the pH hypothesis, the metabolic hypotheses, the amino acid hypothesis, and the ketone hypothesis.

Carbenoxolone (CBX) is a widely used gap junctional blocker. Considering several reports indicating that transient gap junctional blockade could be a favourable intervention following injuries to central nervous tissue, and some current enthusiasm in studies using systemic injections of CBX, it is imperative to consider the penetration of CBX into central nervous tissue after systemic administrations. So far, only very indirect evidence suggests that CBX penetrates into the central nervous system after systemic administrations. We thus determined the amounts of CBX present in the blood and the cerebrospinal fluid of rats after intraperitoneal administration, using high performance liquid chromatography. CBX was found in the blood of the animals, up to 90 minutes post-injection. However, the cerebrospinal fluid concentration of CBX was negligible. Thus, we conclude that, most likely, CBX does not penetrate the blood brain barrier and therefore recommend careful consideration in the m...

The mechanism of action of the ketogenic diet, a therapy for refractory epilepsy, is unknown. Our hypothesis is that acetone, one of three ketones elevated by the ketogenic diet, is directly responsible for the diet&#39;s anticonvulsant effects. This study examined the basic concepts of this hypothesis. Rats were acutely injected with acetone intraperitoneally at doses of 1 or 10 mmol/kg, or received acetone chronically in drinking water (1% v/v) for 10 days before being injected with a 1 mmol/kg dose of acetone. Controls consumed regular water and were injected with vehicle. A pentylenetetrazole seizure test was administered 15 min after the injections. Following the test, acetone was measured in the cerebrospinal fluid. A 10 mmol/kg injection of acetone suppressed seizures in 60% of rats (P&lt;0.05). A chronic administration of acetone followed by a 1 mmol/kg injection suppressed seizures in 47% of rats (P&lt;0.05). The acetone concentrations in these rats were 10.3I2.3 and 1.0I0....

Ketogenic diets are used therapeutically to treat intractable seizures. Clinically, it appears that the maintenance of ketosis is crucial to the efficacy of the diet in ameliorating seizures. To understand how ketosis and seizure protection are related, a reliable, noninvasive measure of ketosis that can be performed frequently with minimal discomfort is needed. The objective was to determine which index, breath acetone or urinary acetoacetate, is more strongly related to the plasma ketones acetoacetate and beta-hydroxybutyrate. After fasting overnight for 12 h, 12 healthy adults consumed 4 ketogenic meals over 12 h. Blood, breath, and urine samples were collected hourly. Blood was analyzed for plasma acetoacetate and beta-hydroxybutyrate, breath for acetone, and urine for acetoacetate. By the end of the 12-h dietary treatment, plasma acetoacetate, plasma beta-hydroxybutyrate, and breath acetone had increased 3.5-fold, whereas urinary acetoacetate increased 13-fold when measured enz...

The mechanism of a high-fat, low-carbohydrate ketogenic diet (KD) in alleviating drug-resistant epilepsy is unknown but may be related to systemic ketosis induced under this treatment. The need for frequent measurement of systemic ketosis, which is essential for improving maintenance of the KD in patients and for studying mechanism of the KD action, has prompted us to validate the breath acetone test as a fast, reliable, and noninvasive tool for ketosis assessment. A rat model of the KD that allowed frequent blood sampling was used to investigate how well breath acetone reflects plasma beta-hydroxybutyrate (beta-HBA), the most commonly measured ketone body. Rat pups (20 days of age) were introduced to and maintained on a KD or control diet for 33 days. During this period, breath acetone, plasma beta-HBA, blood glucose, and body weight were measured approximately every 4th day. A correlational analysis of breath acetone and plasma beta-HBA was conducted. Breath acetone was found to b...