Population pharmacokinetic modeling and simulation to support qualification of pyridoxic acid as endogenous biomarker of OAT1/3 renal transporters.

Renal clearance of many drugs is mediated by renal organic anion transporters OAT1/3 and inhibition of these transporters may lead to drug-drug interactions (DDIs). Pyridoxic acid (PDA) and homovanillic acid (HVA) were indicated as potential biomarkers of OAT1/3. The objective of this study was to develop a population pharmacokinetic model for PDA and HVA to support biomarker qualification. Simultaneous fitting of biomarker plasma and urine data in the presence and absence of potent OAT1/3 inhibitor (probenecid, 500 mg every 6 h) was performed. The impact of study design (multiple vs. single dose of OAT1/3 inhibitor) and ability to detect interactions in the presence of weak/moderate OAT1/3 inhibitors was investigated, together with corresponding power calculations. The population models developed successfully described biomarker baseline and PDA/HVA OAT1/3-mediated interaction data. No prominent effect of circadian rhythm on PDA and HVA individual baseline levels was evident. Renal elimination contributed greater than 80% to total clearance of both endogenous biomarkers investigated. Estimated probenecid unbound in vivo OAT inhibitory constant was up to 6.4-fold lower than in vitro values obtained with PDA as a probe. The PDA model was successfully verified against independent literature reported datasets. No significant difference in power of DDI detection was found between multiple and single dose study design when using the same total daily dose of 2000 mg probenecid. Model-based simulations and power calculations confirmed sensitivity and robustness of plasma PDA data to identify weak, moderate, and strong OAT1/3 inhibitors in an adequately powered clinical study to support optimal design of prospective clinical OAT1/3 interaction studies.

Metabolomic analysis on blood of transgenic mice overexpressing PGC-1α in skeletal muscle.

PGC-1α expression increases in skeletal muscles during exercise and regulates the transcription of many target genes. In this study, we conducted a metabolomic analysis on the blood of transgenic mice overexpressing PGC-1α in its skeletal muscle (PGC-1α-Tg mice) using CE-TOFMS. The blood level of homovanillic acid (dopamine metabolite) and the gene expression of dopamine metabolic enzyme in the skeletal muscle of PGC-1α-Tg mice were high. The blood level of 5-methoxyindoleacetic acid was also high in PGC-1α-Tg mice. The blood levels of branched-chain α-keto acids and ß-alanine were low in PGC-1α-Tg mice. These metabolites in the skeletal muscle were present in low concentration. The changes in these metabolites may reflect the skeletal muscle condition with increasing PGC-1α, such as exercise.

The Presence of Caffeic Acid in Cerebrospinal Fluid: Evidence That Dietary Polyphenols Can Cross the Blood-Brain Barrier in Humans.

Epidemiological data indicate that a diet rich in plant polyphenols has a positive effect on brain functions, improving memory and cognition in humans. Direct activity of ingested phenolics on brain neurons may be one of plausible mechanisms explaining these data. This also suggests that some phenolics can cross the blood-brain barrier and be present in the brain or cerebrospinal fluid. We measured 12 phenolics (a combination of the solid-phase extraction technique with high-performance liquid chromatography) in cerebrospinal fluid and matched plasma samples from 28 patients undergoing diagnostic lumbar puncture due to neurological disorders. Homovanillic acid, 3-hydroxyphenyl acetic acid and caffeic acid were detectable in cerebrospinal fluid reaching concentrations (median; interquartile range) 0.18; 0.14 µmol/L, 4.35; 7.36 µmol/L and 0.02; 0.01 µmol/L, respectively. Plasma concentrations of caffeic acid (0.03; 0.01 µmol/L) did not correlate with those in cerebrospinal fluid (ρ = -0.109, p = 0.58). Because food (fruits and vegetables) is the only source of caffeic acid in human body fluids, our results indicate that the same dietary phenolics can cross blood-brain barrier in humans, and that transportation of caffeic acid through this barrier is not the result of simple or facilitated diffusion.

Effects of daily L-dopa administration on learning and brain structure in older adults undergoing cognitive training: a randomised clinical trial.

Cognitive aging creates major individual and societal burden, motivating search for treatment and preventive care strategies. Behavioural interventions can improve cognitive performance in older age, but effects are small. Basic research has implicated dopaminergic signalling in plasticity. We investigated whether supplementation with the dopamine-precursor L-dopa improves effects of cognitive training on performance. Sixty-three participants for this randomised, parallel-group, double-blind, placebo-controlled trial were recruited via newspaper advertisements. Inclusion criteria were: age of 65-75 years, Mini-Mental State Examination score >25, absence of serious medical conditions. Eligible subjects were randomly allocated to either receive 100/25 mg L-dopa/benserazide (n = 32) or placebo (n = 31) prior to each of twenty cognitive training sessions administered during a four-week period. Participants and staff were blinded to group assignment. Primary outcomes were latent variables of spatial and verbal fluid intelligence. Compared to the placebo group, subjects receiving L-dopa improved less in spatial intelligence (-0.267 SDs; 95%CI [-0.498, -0.036]; p = 0.024). Change in verbal intelligence did not significantly differ between the groups (-0.081 SDs, 95%CI [-0.242, 0.080]; p = 0.323). Subjects receiving L-dopa also progressed slower through the training and the groups displayed differential volumetric changes in the midbrain. No statistically significant differences were found for the secondary cognitive outcomes. Adverse events occurred for 10 (31%) and 7 (23%) participants in the active and control groups, correspondingly. The results speak against early pharmacological interventions in older healthy adults to improve broader cognitive functions by targeting the dopaminergic system and provide no support for learning-enhancing properties of L-dopa supplements in the healthy elderly. The findings warrant closer investigation about the cognitive effects of early dopamine-replacement therapy in neurological disorders. This trial was preregistered at the European Clinical Trial Registry, EudraCT#2016-000891-54 (2016-10-05).

Plasma levels of dopamine metabolite correlate with mismatch negativity in patients with schizophrenia.

AIM: Mismatch negativity (MMN) deficit is one of the most robust and replicable findings in schizophrenia, and primarily reflects deficient functioning of the N-methyl-D-aspartate (NMDA) receptor system. Although the dopamine receptor is known not to modulate MMN over the short term, it is unclear whether the dopamine system affects MMN in the long term. METHODS: We explored correlations between MMN and levels of plasma dopamine and serotonin metabolites in 18 patients with schizophrenia psychiatrically evaluated with the Positive and Negative Syndrome Scale (PANSS). RESULTS: A significant negative correlation exists between MMN amplitude and plasma levels of dopamine metabolites. Plasma serotonin metabolite levels were not correlated with MMN. The PANSS total score and Negative score also showed negative correlations with MMN amplitude. CONCLUSION: The usual strong therapeutic blockade of dopamine receptors applied in cases of schizophrenia may reduce MMN over the long term.

Plasma monoamines change under dopamine supersensitivity psychosis in patients with schizophrenia: A comparison with first-episode psychosis.

BACKGROUND: Patients with first-episode psychosis respond well to initial antipsychotic treatment, but among patients experiencing a relapse of psychosis, the response rate falls to approximately 30%. The mechanism of this discrepancy has not been clarified, but the development of dopamine supersensitivity psychosis with the underlying up-regulation of post-synaptic dopamine D2 receptors could be involved in this lesser response. It is uncertain whether elevated dopamine synthesis and release occurs in patients with dopamine supersensitivity psychosis, in contrast to those with first-episode psychosis. PATIENTS AND METHODS: We examined a first-episode psychosis group (n=6) and a chronic schizophrenia group, i.e. patients experiencing relapse (n=23) including those who relapsed due to dopamine supersensitivity psychosis (n=18). Following the initiation of treatment, we measured the patients' blood concentrations of homovanillic acid and 3-methoxy-4-hydroxyphenylglycol at two weeks and four weeks after the baseline measurements. RESULTS: The first-episode psychosis group tended to show decreased homovanillic acid, accompanied by an improvement of symptoms. The chronic schizophrenia group showed no alteration of homovanillic acid or 3-methoxy-4-hydroxyphenylglycol over the treatment period. These results were the same in the dopamine supersensitivity psychosis patients alone. CONCLUSIONS: Our findings suggest that unlike first-episode psychosis, the release of dopamine from presynaptic neurons did not increase in relapse episodes in the patients with dopamine supersensitivity psychosis. This indirectly indicates that the development of supersensitivity of post-synapse dopamine D2 receptor is involved in relapse in dopamine supersensitivity psychosis patients.

Plasma levels of 3-methoxy-4-hydroxyphenylglycol levels, number of hospitalization and cognitive function predicts the cognitive effect of atypical antipsychotic monotherapy in patients with acute schizophrenia.

Although the effects of atypical antipsychotics with regard to improving neurocognitive function are not sufficiently high. The present study applied an atypical antipsychotic monotherapy for patients with acute schizophrenia to (1) examine the percentage of patients who respond well to this treatment, (2) explore the factors that predict response (e.g. the improvement of neurocognition), and (3) identify the factors associated with improved neurocognitive function. We studied 40 patients with acute schizophrenia who had received atypical antipsychotic monotherapy for 24 weeks. The following parameters were evaluated at baseline and 24 weeks after the start of treatment: psychotic symptoms, neurocognitive function, and blood biological markers including homovanillic acid, 3-methoxy-4-hydroxyphenylglycol, and brain-derived neurotrophic factor. Marked improvements in neurocognitive function were noted in 7.5%-25% of patients. The factors that significantly predicted neurocognitive function improvement were the frequency of hospitalization (verbal memory and verbal fluency), 3-methoxy-4-hydroxyphenylglycol (verbal fluency and executive function), and verbal memory (working memory). Approximately 20% of the patients showed good response to treatment with antipsychotics. Frequency of hospitalization, 3-methoxy-4-hydroxyphenylglycol level, and other parameters predicted responsiveness to these drug therapies. Thus, it might be useful to apply these factors to predict responses to treatment.

Low- and high-dose aripiprazole augmentation and plasma levels of homovanillic acid in major depressive disorder: A randomized, open-label study.

OBJECTIVE: This randomized controlled study evaluated the efficacy of low-dose (LD) and high-dose (HD) aripiprazole augmentation in major depressive disorder. Additionally, we examined the relationship between clinical response and changes in plasma homovanillic acid (pHVA) levels during aripiprazole augmentation. METHODS: Thirty-one patients with inadequate response to antidepressants were randomized to receive adjunctive treatment with LD (3 mg/day, n = 17) or HD (up to 12 mg/day, n = 14) aripiprazole for 6 weeks. We evaluated the Montgomery-Åsberg Depression Rating Scale (MADRS) and measured pHVA at baseline, Week 2, and end point. RESULTS: Both LD and HD aripiprazole significantly decreased MADRS score after 6 weeks, and the response rate was higher in HD aripiprazole group at end point. HD aripiprazole significantly decreased MADRS score at Week 2 compared with LD aripiprazole (p = .015). There was a significant difference in changes in pHVA between responders and nonresponders, showing pHVA decreased significantly in responders at Week 2 (p = .044). CONCLUSIONS: Increasing aripiprazole from the early period appeared useful for immediate response, although caution is needed when increasing the dose >6 mg/day. pHVA may be a possible indicator of the response to aripiprazole augmentation. Caution is needed in interpreting these findings because of the small sample size.

Sampling issues of cerebrospinal fluid and plasma monoamines: Investigation of the circadian rhythm and rostrocaudal concentration gradient.

Biomarkers for neurodegenerative dementias offer interesting prospects regarding diagnosis and disease monitoring. Monoamines such as dopamine, (nor)adrenaline, serotonin (5-hydroxytryptamine or 5-HT), and their respective metabolites homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid, 3-methoxy-4-hydroxyphenylglycol (MHPG), and 5-hydroxyindoleacetic acid (5-HIAA), were shown to be altered in dementia, including Alzheimer's disease (AD). Biomarker research is hampered by potential confounds including the influence of time of day and volume of cerebrospinal fluid (CSF) collected. Therefore, the possibility of a circadian rhythm in CSF and plasma, and the presence of a rostrocaudal concentration gradient (RCG) in CSF for aforementioned monoamines/metabolites, were investigated. Circadian rhythmicity was assessed using reversed-phase ultra-high performance liquid chromatography with electrochemical detection (RP-UHPLC-ECD) to measure monoamine/metabolite concentrations in 271 paired CSF and plasma samples, successively collected over a period of 30 h and derived from eight healthy subjects. Plasma samples were also analyzed for melatonin, serving as positive control analyte, using ELISA. The RCG examination entailed RP-UHPLC-ECD analyses on five consecutive CSF samples derived from 10 patients with AD and 10 non-AD/control subjects. Besides a diurnal rhythm for melatonin, we found a similar rhythmicity for plasma HVA, with acrophases occurring between 02:00 and 06:00 h, in four out of seven subjects. Three and two subjects showed a circadian rhythm for CSF HVA and 5-HIAA, respectively. No rhythmicity was observed in any other compound. We found that only CSF MHPG, HVA and 5-HIAA levels differed across CSF fractions, and that these changes in 5-HIAA levels varied in the AD versus non-AD/control group. Positive correlations between CSF volume and HVA and 5-HIAA levels, indicative of a RCG, were also observed. Such a RCG could not be detected for the other monoamines/metabolites. Our results stress the importance of standardizing sampling procedures of biological fluids with respect to time of day, volume and number of samples.

Differences in potential biomarkers of delirium between acutely ill medical and elective cardiac surgery patients.

BACKGROUND/AIMS: The pathophysiology of delirium is poorly understood. Increasing evidence suggests that different pathways might be involved in the pathophysiology depending on the population studied. The aim of the present study was to investigate potential differences in mean plasma levels of neopterin, amino acids, amino acid ratios and homovanillic acid between two groups of patients with delirium. METHODS: Data from acutely ill medical patients aged 65 years and older, and patients aged 70 years and older undergoing elective cardiac surgery, were used. Differences in biomarker levels between the groups were investigated using univariate ANOVA with adjustments for age, sex, comorbidities, C-reactive protein (CRP) and the estimated glomerular filtration rate (eGFR), where appropriate. Linear regression analysis was used to identify potential determinants of the investigated biochemical markers. RESULTS: Eighty patients with delirium were included (23 acutely ill medical patients and 57 elective cardiac surgery patients). After adjustment, higher mean neopterin levels (93.1 vs 47.3 nmol/L, P=0.001) and higher phenylalanine/tyrosine ratios (1.39 vs 1.15, P=0.032) were found in acutely ill medical patients when compared to elective cardiac surgery patients. CRP levels were positively correlated with neopterin levels in acutely ill medical patients, explaining 28.4% of the variance in neopterin levels. eGFR was negatively correlated with neopterin in elective cardiac surgery patients, explaining 53.7% of the variance in neopterin levels. CONCLUSION: In this study, we found differences in mean neopterin levels and phenylalanine/tyrosine ratios between acutely ill medical and elective cardiac surgery patients with delirium. Moreover, our findings may suggest that in acutely ill medical patients, neopterin levels are mainly determined by inflammation/oxidative stress whereas in elective cardiac surgery patients, neopterin levels are mainly driven by renal function/fluid status. These findings suggest that the markers and pathways that might be involved in the pathophysiology of delirium may differ between specific groups of patients.

Cerebrospinal fluid biogenic amines depletion and brain atrophy in adult patients with phenylketonuria.

Biogenic amines synthesis in phenylketonuria (PKU) patients with high phenylalanine (Phe) concentration is thought to be impaired due to inhibition of tyrosine and tryptophan hydroxylases and competition with amino acids at the blood-brain barrier. Dopamine and serotonin deficits might explain brain damage and progressive neuropsychiatric impairment in adult PKU patients. Ten early treated adult PKU patients (mean age 38.2 years) and 15 age-matched controls entered the study. Plasma and cerebrospinal fluid (CSF) Phe, 5-hydroxyindoleacetic acid (5-HIAA), 5-hydroxytryptophan (5-HTP), 3,4-dihydroxy-l-phenylalanine (l-DOPA) and homovanillic acid (HVA) were analyzed. Voxel-based morphometry statistical nonparametric mapping was used to test the age-corrected correlation between gray matter atrophy and CSF biogenic amines levels. 5-HIAA and 5-HTP were significantly reduced in PKU patients compared to controls. Significant negative correlations were found between CSF 5-HIAA, HVA, and 5-HTP and Phe levels. A decrease in 5-HIAA and 5-HTP concentrations correlated with precuneus and frontal atrophy, respectively. Lower HVA levels correlated with occipital atrophy. Biogenic amines deficits correlate with specific brain atrophy patterns in adult PKU patients, in line with serotonin and dopamine projections. These findings may support a more rigorous Phe control in adult PKU to prevent neurotransmitter depletion and accelerated brain damage due to aging.

Relationship between serum homovanillic acid, DRD2 C957T (rs6277), and hDAT A559V (rs28364997) polymorphisms and developmental stuttering.

The involvement of the brain dopamine system in the pathophysiology of developmental stuttering has been previously suggested. In the present study, we aimed to investigate the relationship between developmental stuttering in children and the levels of serum homovanillic acid (HVA), dopamine D2 receptor (DRD2) C957T (rs6277), and solute carrier family 6 member 3 (SLC6A3) human dopamine transporter (hDAT) A559V (rs28364997) single-nucleotide polymorphisms. In a case-control study, serum level of HVA, DRD2 C957T, and DAT A559V were compared between 85 children who stuttered (CWS) and 85 age- and sex-matched children who did not stutter (CWNS). Although serum level of HVA was higher among the CWS (median = 25.50 ng/mL) than that in the CWNS (median = 17.40 ng/mL), the difference between the two groups was not significant (p = 0.43). No significant correlation was observed between age and the level of HVA among all the participants (r = -0.15, p = 0.06), nor was there any correlation among the CWS (r = -0.19, p = 0.14) or among the CWNS (r = -0.13, p = 0.27) according to the Spearman correlation coefficient. On the other hand, there was a significant negative correlation between age from stuttering onset and the serum level of HVA among the CWS group (r = -0.32, p = 0.01). The Spearman correlation coefficient did not indicate any significant correlation between stuttering severity and HVA in CWS (r = -0.06, p = 0.59). The mutant allele of hDAT A559V was observed neither in the CWS nor in the controls. The allele frequencies of DRD2 C957T were not significantly different between the CWS and the CWNS; however, the frequency of the TT genotype was significantly higher among the CWS (p = 0.02), which was associated with 2.25-fold susceptibility to stuttering (OR = 2.25, 95% CI = 1.03 to 4.90, p = 0.04). Our findings suggest that the serum level of HVA might be a biomarker for dopaminergic involvement in the pathogenesis of stuttering. Moreover, the present study indicates that the DRD2 C957T polymorphism might be a risk factor for the development of stuttering among Iranian Kurdish population.

Usefulness of fluorodeoxyglucose positron emission tomography/computed tomography for detection of a neuroblastic nodule in a ganglioneuroblastoma: a case report.

BACKGROUND: Ganglioneuroblastoma, nodular is defined as a composite tumor of biologically distinct clones. The peripheral neuroblastic tumors in this category are characterized by the presence of grossly visible neuroblastoma nodules coexisting with ganglioneuroblastoma, intermixed, or with ganglioneuroma. Making a correct diagnosis of ganglioneuroblastoma, nodular is often difficult by biopsy or partial tumor resection, because the neuroblastic nodule could be hidden and not sampled for pathological examination. CASE PRESENTATION: We report a case of a Japanese boy aged 3 years, 8 months, with an unresectable abdominal tumor and elevated vanillylmandelic acid and homovanillic acid levels. The initial biopsy was ganglioneuroma. However, after the second biopsy from a hidden neuroblastoma nodule that was clearly highlighted by fluorodeoxyglucose positron emission tomography/computed tomography, we reached the diagnosis of ganglioneuroblastoma, nodular. Because the nodule demonstrated neuroblastoma, differentiating subtype, with a low mitosis-karyorrhexis index (favorable histology) and nonamplified MYCN, the boy was treated according to the intermediate-risk protocol and is now alive and well 4 years after the diagnosis. CONCLUSIONS: This case illustrates the critical role of fluorodeoxyglucose positron emission tomography/computed tomography for detecting a neuroblastoma nodule in a ganglioneuroblastoma.

Monoaminergic Markers Across the Cognitive Spectrum of Lewy Body Disease.

BACKGROUND: Lewy body disorders, including Parkinson's disease (PD), Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB), are characterized by profound central and peripheral monoaminergic dysfunction. OBJECTIVE: To investigate whether these alterations depend on dementia status, we measured cerebrospinal fluid (CSF) and serum monoamine and metabolite levels across subgroups of the cognitive spectrum, and evaluated their marker potential afterwards. METHODS: In total, 153 subjects were included, of which 43 healthy controls (HC), 28 PD patients with normal cognition (PD-NC), 26 patients with PD and mild cognitive impairment (PD-MCI), 18 PDD patients, and 38 DLB patients. The levels of monoamines and metabolites in paired CSF and serum samples were analyzed applying reversed-phase high-performance liquid chromatography with electrochemical detection. RESULTS: Firstly, when comparing subgroups, CSF 3-methoxy-4-hydroxyphenylglycol (MHPG) levels were found lowest in HC and PD-NC groups and significantly higher in PDD/DLB patients. In addition, CSF 5-hydroxyindoleacetic acid (5-HIAA) levels differed significantly between HC and PD-MCI/PDD, and DLB patients (P≤0.001), but not between HC and PD-NC patients. Secondly, when performing logistic regression, it was shown that particularly CSF/serum MHPG levels and the serum MHPG to noradrenaline (NA) ratio effectively differentiated between HC and (non-)pooled PD subgroups (AUC = 0.914-0.956), and PDD and DLB patients (AUC = 0.822), respectively. Furthermore, CSF 5-HIAA was the most discriminative parameter to differentiate between PD-NC and PD-MCI (AUC = 0.808), and, PD-NC and PDD subgroups (AUC = 0.916). CONCLUSIONS: Our data revealed that especially alterations of the noradrenergic neurotransmitter system could distinguish between Lewy body disorder subtypes, pinpointing CSF/serum MHPG and NA as potential stage markers across the cognitive spectrum.

Involvement of Aromatic Metabolites in the Pathogenesis of Septic Shock.

INTRODUCTION: We hypothesized that aromatic microbial metabolites (AMM), such as phenyllactic (PhLA), p-hydroxyphenylacetic (p-HPhAA), and p-hydroxyphenyllactic (p-HPhLA) acids, contribute to the pathogenesis of septic shock. METHODS: Clinical and laboratory data of patients with community-acquired pneumonia were obtained on intensive care unit admission and the next day. Patients were divided into two groups based on septic shock presence or absence. The levels of AMM (PhLA, p-HPhAA, p-HPhLA, and their sum, ∑3AMM), catecholamine metabolites (3,4-dihydroxymandelic [DHMA], 3,4-dihydroxyphenylacetic [DOPAC], and homovanillic [HVA] acids), lactate, N-terminal pro-brain natriuretic peptide (NT-proBNP), inducible nitric oxide synthase (iNOS), and procalcitonin (PCT) were compared. Correlations between AMM and clinical and laboratory data were calculated. RESULTS: There were 20 patients in the septic shock group and 21 in the nonseptic shock group. On admission, the septic shock patients demonstrated significantly higher levels of PhLA (2.3 vs. 0.8 µmol/L), p-HPhAA (4.6 vs. 1.4 µmol/L), p-HPhLA (7.4 vs. 2.6 µmol/L), HVA, lactate, and significantly lower levels of iNOS. The next day, the two groups also showed significant differences in the levels of PCT and NT-proBNP. The correlation between ∑3AMM and presence of shock, levels of lactate, HVA, and NT-proBNP on admission was 0.44, 0.67, 0.57, and 0.38, respectively, and the correlation on the next day was 0.59, 0.73, 0.76, and 0.6, respectively (P < 0.01). These findings can be explained by the ability of AMM to reduce tyrosine hydroxylase activity, thus limiting the synthesis of catecholamines. CONCLUSIONS: AMM are involved in the pathogenesis of septic shock.

Discovery and Validation of Pyridoxic Acid and Homovanillic Acid as Novel Endogenous Plasma Biomarkers of Organic Anion Transporter (OAT) 1 and OAT3 in Cynomolgus Monkeys.

Perturbation of organic anion transporter (OAT) 1- and OAT3-mediated transport can alter the exposure, efficacy, and safety of drugs. Although there have been reports of the endogenous biomarkers for OAT1/3, none of these have all of the characteristics required for a clinical useful biomarker. Cynomolgus monkeys were treated with intravenous probenecid (PROB) at a dose of 40 mg/kg in this study. As expected, PROB increased the area under the plasma concentration-time curve (AUC) of coadministered furosemide, a known substrate of OAT1 and OAT3, by 4.1-fold, consistent with the values reported in humans (3.1- to 3.7-fold). Of the 233 plasma metabolites analyzed using a liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics method, 29 metabolites, including pyridoxic acid (PDA) and homovanillic acid (HVA), were significantly increased after either 1 or 3 hours in plasma from the monkeys pretreated with PROB compared with the treated animals. The plasma of animals was then subjected to targeted LC-MS/MS analysis, which confirmed that the PDA and HVA AUCs increased by approximately 2- to 3-fold by PROB pretreatments. PROB also increased the plasma concentrations of hexadecanedioic acid (HDA) and tetradecanedioic acid (TDA), although the increases were not statistically significant. Moreover, transporter profiling assessed using stable cell lines constitutively expressing transporters demonstrated that PDA and HVA are substrates for human OAT1, OAT3, OAT2 (HVA), and OAT4 (PDA), but not OCT2, MATE1, MATE2K, OATP1B1, OATP1B3, and sodium taurocholate cotransporting polypeptide. Collectively, these findings suggest that PDA and HVA might serve as blood-based endogenous probes of cynomolgus monkey OAT1 and OAT3, and investigation of PDA and HVA as circulating endogenous biomarkers of human OAT1 and OAT3 function is warranted.

Dopamine in high-risk populations: A comparison of subjects with 22q11.2 deletion syndrome and subjects at ultra high-risk for psychosis.

Striatal dopamine (DA) dysfunction has been consistently reported in psychotic disorders. Differences and similarities in the pathogenesis between populations at clinical and genetic risk for developing psychosis are yet to be established. Here we explored markers of dopamine (DA) function in subjects meeting clinically ultra-high risk criteria for psychosis (UHR) and in subjects with 22q11.2 deletion syndrome (22q11DS), a genetic condition associated with significant risk for developing psychotic disorders. Single Photon Emission Computed Tomography (SPECT) with 123I-labelled iodobenzamide ([123I]IBZM) was used to measure striatal DA D2/3 receptor binding potential (D2R BPND). Also, peripheral DAergic markers were assessed in serum and urine (plasma prolactin (pPRL), plasma homovanillic acid (pHVA) and urine DA(uDA)). No significant difference in striatal D2R BPND was found between UHR and 22q11DS subjects. Compared to UHR subjects, pPRL and pHVA were lower and uDA levels were higher in the 22q11DS subjects. However, after correcting for age and gender, only pPRL as significantly lower in the 22q11DS patients. These results may suggest that there are differences in DAergic markers between subjects with UHR and with 22q11DS that may reflect differences in the pathways to psychosis. However, bigger samples are needed to replicate these findings.

Metabolomic Alterations Associated with Cause of CKD.

BACKGROUND AND OBJECTIVES: Causes of CKD differ in prognosis and treatment. Metabolomic indicators of CKD cause may provide clues regarding the different physiologic processes underlying CKD development and progression. DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS: Metabolites were quantified from serum samples of participants in the Modification of Diet in Renal Disease (MDRD) Study, a randomized controlled trial of dietary protein restriction and BP control, using untargeted reverse phase ultraperformance liquid chromatography tandem mass spectrometry quantification. Known, nondrug metabolites (n=687) were log-transformed and analyzed to discover associations with CKD cause (polycystic kidney disease, glomerular disease, and other cause). Discovery was performed in Study B, a substudy of MDRD with low GFR (n=166), and replication was performed in Study A, a substudy of MDRD with higher GFR (n=423). RESULTS: Overall in MDRD, average participant age was 51 years and 61% were men. In the discovery study (Study B), 29% of participants had polycystic kidney disease, 28% had glomerular disease, and 43% had CKD of another cause; in the replication study (Study A), the percentages were 28%, 24%, and 48%, respectively. In the discovery analysis, adjusted for demographics, randomization group, body mass index, hypertensive medications, measured GFR, log-transformed proteinuria, and estimated protein intake, seven metabolites (16-hydroxypalmitate, kynurenate, homovanillate sulfate, N2,N2-dimethylguanosine, hippurate, homocitrulline, and 1,5-anhydroglucitol) were associated with CKD cause after correction for multiple comparisons (P<0.0008). Five of these metabolite associations (16-hydroxypalmitate, kynurenate, homovanillate sulfate, N2,N2-dimethylguanosine, and hippurate) were replicated in Study A (P<0.007), with all replicated metabolites exhibiting higher levels in polycystic kidney disease and lower levels in glomerular disease compared with CKD of other causes. CONCLUSIONS: Metabolomic profiling identified several metabolites strongly associated with cause of CKD.

Depressive symptoms, monoamines levels, MAO-B activity and effect of treatment in a subset of depressed individuals from government sector hospital at Karachi.

Depression is one of the leading causes of disability in developing countries including Pakistan. This study was designed to assess the frequency and severity of depressive symptoms, monoamines and their metabolite levels, MAO-B activities before and after treatment with antidepressants in a sub-set of Karachi population in Pakistan. Drug naive depressed subjects were evaluated before and after treatment with selective serotonin reuptake inhibitors. Symptoms of depressed mood and anxiety psychic (90%) were more frequent whereas, suicidal thoughts (~50%) and feelings of guilt (~30%) were less common. Hamilton Depression Rating Scale scores were 21.4 ± 0.8 in both genders with a significantly higher score (1.3x) in females. Homovanillic acid, 5- hydroxyindoleacetic acid and MAO-B activity were significantly higher 43%, 66% and 25% respectively, in depressed than normal subjects. A significant decline after 2 weeks treatment in HDRS scores with fluoxetine (19%) and paroxetine (40%) and in MAO-B activity (20%) was observed. In conclusion, in our population early decline in HDRS scores supports that they are SSRIs responders, whereas a concomitant reduction in MAO-B activities indicates that it can be considered as one of the parameters for early detection of response. Additionally, the low frequency of suicidal thoughts could be associated with higher levels of monoamine metabolites.