ABSTRACT. Objective. To investigate the relationship between plasma and synovial fluid (SF) metab... more 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... more 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. ... more 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 ... more 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...
Journal of Liquid Chromatography & Related Technologies
Abstract Objectives: The objective of this study was the investigation of age- and sex-associatio... more 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
Multiple factors can help predict knee osteoarthritis (OA) patients from healthy individuals, inc... more Multiple factors can help predict knee osteoarthritis (OA) patients from healthy individuals, including age, sex, and BMI, and possibly metabolite levels. Using plasma from individuals with primary OA undergoing total knee replacement and healthy volunteers, we measured lysophosphatidylcholine (lysoPC) and phosphatidylcholine (PC) analogues by metabolomics. Populations were stratified on demographic factors and lysoPC and PC analogue signatures were determined by univariate receiver-operator curve (AUC) analysis. Using signatures, multivariate classification modeling was performed using various algorithms to select the most consistent method as measured by AUC differences between resampled training and test sets. Lists of metabolites indicative of OA [AUC > 0.5] were identified for each stratum. The signature from males age > 50 years old encompassed the majority of identified metabolites, suggesting lysoPCs and PCs are dominant indicators of OA in older males. Principal component regression with logistic regression was the most consistent multivariate classification algorithm tested. Using this algorithm, classification of older males had fair power to classify OA patients from healthy individuals. Thus, individual levels of lysoPC and PC analogues may be indicative of individuals with OA in older populations, particularly males. Our metabolite signature modeling method is likely to increase classification power in validation cohorts.
Menopause is an endocrine-related transition that induces a number of physiological and potential... more Menopause is an endocrine-related transition that induces a number of physiological and potentially pathological changes in middle-aged and elderly women. The intention of this research was to investigate the influence of menopause on the intricate relationships between major biochemical metabolites. The study involved metabolic profiling of 186 metabolic markers measured in blood plasma collected from 120 healthy female participants. We developed a method of network analysis using differential correlation that enabled us to detect and characterize differences in metabolites and changes in interrelationships in preand post-menopausal women. A topological analysis was performed on the differential network that uncovered metabolite differences in pre-and post-menopausal women. In this analysis, our method identified two key metabolites, sphingomyelins and phosphatidylcholines, which may be useful in directing further studies into menopause-specific differences in the metabolome, and how these differences may underlie the body's response to stress and disease following the transition from pre-to post-menopausal status for women.
Purpose: Anterior cruciate ligament tears (ACLT) are associated with a large knee effusion which ... more Purpose: Anterior cruciate ligament tears (ACLT) are associated with a large knee effusion which likely contains an early inflammatory response that may represent an early attempt at healing but ultimately leads to cartilage degeneration. Little is known about the composition of the synovial fluid (SF) in effusions after ACLT and whether it changes with time from injury. The purpose of this study is to determine the pattern of SF biomarkers after ACLT to test the hypotheses that it (a) differs from the pattern of SF biomarkers in knees with OA, (b) exhibits a response dependent on time-frominjury, and (c) varies based on the presence or absence of concomitant meniscus injury. Methods: SF was aspirated in the clinic from patients with ACLTs without any evidence for OA (N ¼ 13) and from patients with moderate to severe OA (N ¼ 16). Assessment of numerous pro-and anti-inflammatory cytokines, growth factors and chemokines was performed using multiplexed panel of 45 proteins. Nitric oxide (NO) was measured by Griess' reagent system.
Objectives To determine whether pre-existing nephropathy impacts urinary KIM-1 levels, urinary KI... more 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.
Females and males are known to have different abilities to cope with stress and disease. This stu... more Females and males are known to have different abilities to cope with stress and disease. This study was designed to investigate the effect of sex on properties of a complex interlinked network constructed of central biochemical metabolites. The study involved the blood collection and analysis of a large set of blood metabolic markers from a total of 236 healthy participants, which included 140 females and 96 males. Metabolic profiling yielded concentrations of 168 metabolites for each subject. A differential correlation network analysis approach was developed for this study that allowed detection and characterization of interconnection differences in metabolites in males and females. Through topological analysis of the differential network that depicted metabolite differences in the sexes, we identified metabolites with high centralities in this network. These key metabolites were identified as 10 phosphatidylcholines (
Background Accumulating evidence suggests an independent association between osteoarthritis (OA) ... more 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
To test whether type 2 diabetic patients have an elevated level of advanced glycation end-product... more To test whether type 2 diabetic patients have an elevated level of advanced glycation end-products (AGEs) and responsible for altered phosphatidylcholine metabolism, which we recently found to be associated with osteoarthritis (OA) and diabetes mellitus (DM), synovial fluid (SF) and plasma samples were collected from OA patients with and without DM. Hyperglycemia-related AGEs including methylglyoxal (MG), free methylglyoxal-derived hydroimidazolone (MG-H1), and protein bound N-(Carboxymethyl)lysine (CML) and N-(Carboxyethyl)lysine (CEL) levels were measured in both SF and plasma samples using liquid chromatography coupled tandem mass spectrometry methodology. The correlation between these AGEs and phosphatidylcholine acyl-alkyl C34:3 (PC ae C34:3) and C36:3 (PC ae C36:3) were examined. Eighty four patients with knee OA, including 46 with DM and 38 without DM, were included in the study. There was no significant difference in plasma levels of MG, MG-H1, CML, and CEL between OA patients with and without DM. However, the levels of MG and MG-H1, but not CML and CEL in SF were significantly higher in OA patients with DM than in those without (all p 0.04). This association strengthened after adjustment for age, body mass index (BMI), sex and hexose level (p<0.02). Moreover, the levels of MG-H1 in SF was negatively and significantly correlated with PC ae C34:3 (ρ =-0.34; p = 0.02) and PC ae C36:3 (ρ =-0.39; P = 0.03) after the adjustment of age, BMI, sex and hexose level. Our data indicated that the production of non-protein bound AGEs was increased within the OA-affected joint of DM patients. This is associated with changes in phosphatidylcholine metabolism and might be responsible for the observed epidemiological association between OA and DM.
Medical Science Monitor International Medical Journal of Experimental and Clinical Research, Aug 1, 2002
Background: The mechanism of action of the ketogenic diet, a therapy for refractory epilepsy, is ... more 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 f... more 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 controlli... more 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 neu... more 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.
ABSTRACT. Objective. To investigate the relationship between plasma and synovial fluid (SF) metab... more 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... more 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. ... more 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 ... more 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...
Journal of Liquid Chromatography & Related Technologies
Abstract Objectives: The objective of this study was the investigation of age- and sex-associatio... more 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
Multiple factors can help predict knee osteoarthritis (OA) patients from healthy individuals, inc... more Multiple factors can help predict knee osteoarthritis (OA) patients from healthy individuals, including age, sex, and BMI, and possibly metabolite levels. Using plasma from individuals with primary OA undergoing total knee replacement and healthy volunteers, we measured lysophosphatidylcholine (lysoPC) and phosphatidylcholine (PC) analogues by metabolomics. Populations were stratified on demographic factors and lysoPC and PC analogue signatures were determined by univariate receiver-operator curve (AUC) analysis. Using signatures, multivariate classification modeling was performed using various algorithms to select the most consistent method as measured by AUC differences between resampled training and test sets. Lists of metabolites indicative of OA [AUC > 0.5] were identified for each stratum. The signature from males age > 50 years old encompassed the majority of identified metabolites, suggesting lysoPCs and PCs are dominant indicators of OA in older males. Principal component regression with logistic regression was the most consistent multivariate classification algorithm tested. Using this algorithm, classification of older males had fair power to classify OA patients from healthy individuals. Thus, individual levels of lysoPC and PC analogues may be indicative of individuals with OA in older populations, particularly males. Our metabolite signature modeling method is likely to increase classification power in validation cohorts.
Menopause is an endocrine-related transition that induces a number of physiological and potential... more Menopause is an endocrine-related transition that induces a number of physiological and potentially pathological changes in middle-aged and elderly women. The intention of this research was to investigate the influence of menopause on the intricate relationships between major biochemical metabolites. The study involved metabolic profiling of 186 metabolic markers measured in blood plasma collected from 120 healthy female participants. We developed a method of network analysis using differential correlation that enabled us to detect and characterize differences in metabolites and changes in interrelationships in preand post-menopausal women. A topological analysis was performed on the differential network that uncovered metabolite differences in pre-and post-menopausal women. In this analysis, our method identified two key metabolites, sphingomyelins and phosphatidylcholines, which may be useful in directing further studies into menopause-specific differences in the metabolome, and how these differences may underlie the body's response to stress and disease following the transition from pre-to post-menopausal status for women.
Purpose: Anterior cruciate ligament tears (ACLT) are associated with a large knee effusion which ... more Purpose: Anterior cruciate ligament tears (ACLT) are associated with a large knee effusion which likely contains an early inflammatory response that may represent an early attempt at healing but ultimately leads to cartilage degeneration. Little is known about the composition of the synovial fluid (SF) in effusions after ACLT and whether it changes with time from injury. The purpose of this study is to determine the pattern of SF biomarkers after ACLT to test the hypotheses that it (a) differs from the pattern of SF biomarkers in knees with OA, (b) exhibits a response dependent on time-frominjury, and (c) varies based on the presence or absence of concomitant meniscus injury. Methods: SF was aspirated in the clinic from patients with ACLTs without any evidence for OA (N ¼ 13) and from patients with moderate to severe OA (N ¼ 16). Assessment of numerous pro-and anti-inflammatory cytokines, growth factors and chemokines was performed using multiplexed panel of 45 proteins. Nitric oxide (NO) was measured by Griess' reagent system.
Objectives To determine whether pre-existing nephropathy impacts urinary KIM-1 levels, urinary KI... more 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.
Females and males are known to have different abilities to cope with stress and disease. This stu... more Females and males are known to have different abilities to cope with stress and disease. This study was designed to investigate the effect of sex on properties of a complex interlinked network constructed of central biochemical metabolites. The study involved the blood collection and analysis of a large set of blood metabolic markers from a total of 236 healthy participants, which included 140 females and 96 males. Metabolic profiling yielded concentrations of 168 metabolites for each subject. A differential correlation network analysis approach was developed for this study that allowed detection and characterization of interconnection differences in metabolites in males and females. Through topological analysis of the differential network that depicted metabolite differences in the sexes, we identified metabolites with high centralities in this network. These key metabolites were identified as 10 phosphatidylcholines (
Background Accumulating evidence suggests an independent association between osteoarthritis (OA) ... more 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
To test whether type 2 diabetic patients have an elevated level of advanced glycation end-product... more To test whether type 2 diabetic patients have an elevated level of advanced glycation end-products (AGEs) and responsible for altered phosphatidylcholine metabolism, which we recently found to be associated with osteoarthritis (OA) and diabetes mellitus (DM), synovial fluid (SF) and plasma samples were collected from OA patients with and without DM. Hyperglycemia-related AGEs including methylglyoxal (MG), free methylglyoxal-derived hydroimidazolone (MG-H1), and protein bound N-(Carboxymethyl)lysine (CML) and N-(Carboxyethyl)lysine (CEL) levels were measured in both SF and plasma samples using liquid chromatography coupled tandem mass spectrometry methodology. The correlation between these AGEs and phosphatidylcholine acyl-alkyl C34:3 (PC ae C34:3) and C36:3 (PC ae C36:3) were examined. Eighty four patients with knee OA, including 46 with DM and 38 without DM, were included in the study. There was no significant difference in plasma levels of MG, MG-H1, CML, and CEL between OA patients with and without DM. However, the levels of MG and MG-H1, but not CML and CEL in SF were significantly higher in OA patients with DM than in those without (all p 0.04). This association strengthened after adjustment for age, body mass index (BMI), sex and hexose level (p<0.02). Moreover, the levels of MG-H1 in SF was negatively and significantly correlated with PC ae C34:3 (ρ =-0.34; p = 0.02) and PC ae C36:3 (ρ =-0.39; P = 0.03) after the adjustment of age, BMI, sex and hexose level. Our data indicated that the production of non-protein bound AGEs was increased within the OA-affected joint of DM patients. This is associated with changes in phosphatidylcholine metabolism and might be responsible for the observed epidemiological association between OA and DM.
Medical Science Monitor International Medical Journal of Experimental and Clinical Research, Aug 1, 2002
Background: The mechanism of action of the ketogenic diet, a therapy for refractory epilepsy, is ... more 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 f... more 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 controlli... more 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 neu... more 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.
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Papers by Sergei Likhodi