Metabolites In CSF Research Articles

Cerebrospinal fluid metabolites as potential biomarkers for epilepsy: Insights from genome-wide association studies.

While metabolic imbalances have been observed in individuals with epilepsy, the direct involvement of specific metabolites in the development of the condition remains underexplored. A comprehensive analysis of the causality between cerebrospinal fluid metabolites (CSF) and epilepsy is pivotal in discovering innovative therapeutic interventions and prophylactic approaches. Summary data from genome-wide association studies (GWAS) of CSF metabolites and epilepsy subtypes were obtained separately. A total of 338 CSF metabolites were investigated as exposures, and 11 epilepsy phenotypes were examined as the outcomes. A two sample Mendelian randomization (MR) approach was utilized to explore the causal influence of these metabolites on epilepsy. Causality was primarily estimated through inverse variance weighted (IVW) analysis, complemented by a range of sensitivity analyses to ensure result stability. Additionally, reverse MR analysis was performed to explore the possibility of bidirectional causality. The IVW method, reinforced by sensitivity analyses, pinpointed 17 CSF metabolites with causal implications for six epilepsy phenotypes. After False Discovery Rate (FDR) multiple testing correction, two metabolites (Methylmalonate and Gamma-glutamyl-alpha-lysine) were found to have robust causal links to epilepsy (p < 0.05 and FDR<0.05). The other 15 metabolites exhibited suggestive evidence of a causal association (p < 0.05 and FDR>0.05). This study highlights CSF metabolites that could serve as valuable biomarkers and may be critical in developing targeted treatments and preventing epilepsy. This study explores how certain chemicals in the brain fluid might influence the development of epilepsy, aiming to find new ways to treat or prevent it. Researchers looked at the relationship between 338 cerebrospinal fluid metabolites and 11 types of epilepsy using genetic data. They found that 17 of these chemicals could potentially cause six types of epilepsy. Two of these chemicals were strongly linked to epilepsy, suggesting they could be important for creating specific treatments or prevention strategies.

8679 Case: The Sexual, Physical and Psychological Effects of Post-Finasteride Syndrome

Abstract Disclosure: E.M. Lonergan: None. S.M. Maher: None. I. Yaseen: None. D.B. O'Shea: None. Post-finasteride syndrome (PFS) is an increasingly recognised disorder with a myriad of physical and neuropsychiatric symptoms persisting for greater than three months in a small proportion of patients treated with Finasteride. We present the case of a 45-year-old male who was taking oral Finasteride for hair loss. He first presented to endocrinology services having stopped Finasteride after twenty years reporting new onset reduced libido, penile shrinkage, fatigue, new food intolerances and agitated depression which was the predominant symptom in this case. He described the emergence of gynaecomastia, which was evident on examination, as well as muscle atrophy. Biochemistry was unremarkable including testosterone 24.6 nmol/L (8.6-29.0), oestradiol 100 pmol/L (50 – 159), LH 7.1 IU/L (1.7-8.6), FSH 16.8 IU/L (1.5-12.4), urinary free cortisol 177 nmol/24h (12-486) and urinary steroid profile. The patient was offered a trial of IM testosterone for 3 months followed by a course of hCG which he declined after discussing with patients online via a PFS patient forum citing anecdotal pseudo immune downregulation in this cohort. GLP-1 receptor agonist therapy was considered as a second-line treatment option. The patient expressed a preference for hydrocortisone treatment after conducting online research which has not been commenced due to a lack of evidence. The inhibition of 5-alpha-reductase in Finasteride-treated patients has been documented to cause reversible sexual dysfunction. However, with increasing case reports of PFS, it was included in the list of Rare and Genetic Diseases of the NIH in 2015. The syndrome encompasses symptoms and signs seen in our case, as well as erectile dysfunction, decreased ejaculatory volume, infertility, Peyronie’s disease, testicular pain, dry skin, memory problems and insomnia. Suicidal ideation was included in the product label as per FDA mandate in 2022. The literature is largely inconclusive regarding the underlying aetiology, duration, and severity of the disorder. A large retrospective study revealed 0.8% of patients developed sexual dysfunction with persistence in 33% of these cases after drug suspension, the main independent risk factor being drug treatment for longer than 7 months. Neuropsychiatric symptoms are likely related to the presence of 5-alpha-reductase isoforms in the brain with resulting alterations in CSF and plasma neuroactive steroid levels and metabolites. Evidence-based treatment options for PFS are limited. PFS is a rare but debilitating syndrome to which a subset of patients appears to be predisposed, but of which the pathophysiology is poorly understood. Further studies in this regard, as well as an exploration of effective treatment options are required. Presentation: 6/1/2024

A Randomised Controlled Trial of SFX-01 After Subarachnoid Haemorrhage - The SAS Study.

SFX-01 is a novel drug for clinical delivery of sulforaphane (SFN). SFN is a potent nuclear factor erythroid 2-related factor 2 activator that reduces inflammation and oxidation, improving outcomes after subarachnoid haemorrhage (SAH) in animal models. This was a multi-centre, double-blind, placebo-controlled, parallel-group randomised clinical trial to evaluate the safety, pharmacokinetics and efficacy of 28days of SFX-01 300mg BD in patients aged 18-80 with spontaneous SAH and high blood load on CT. Primary outcomes were (1) safety, (2) plasma and CSF SFN and metabolite levels and (3) vasospasm on transcranial doppler ultrasound. Secondary outcomes included CSF haptoglobin and malondialdehyde and clinical outcome on the modified Rankin Scale (mRS) and SAH outcome tool (SAHOT). A total of 105 patients were randomised (54 SFX-01, 51 placebo). There were no differences in adverse events other than nausea (9 SFX-01 (16.7%), 1 placebo (2.0%)). SFN, SFN-glutathione and SFN-N-acetyl-cysteine AUClast were 16.2, 277 and 415h × ng/ml. Plasma SFN was higher in GSTT1 null individuals (t = 2.40, p = 0.023). CSF levels were low with many samples below the lower limit of quantification and predicted by the CSF/serum albumin ratio (R2 = 0.182, p = 0.039). There was no difference in CSF haptoglobin (1.981 95%CI 0.992-3.786, p = 0.052) or malondialdehyde (1.12 95%CI 0.7477-1.687, p = 0.572) or middle cerebral artery flow velocity (1.04 95%CI 0.903-1.211, p = 0.545) or functional outcome (mRS 1.647 95%CI 0.721-3.821, p = 0.237, SAHOT 1.082 95%CI 0.464-2.525, p = 0.855). SFX-01 is safe and effective for the delivery of SFN in acutely unwell patients. SFN penetrated CSF less than expected and did not reduce large vessel vasospasm or improve outcome. Trial registration: NCT02614742 clinicaltrials.gov.

Preclinical metabolism and the disposition of vornorexant/TS-142, a novel dual orexin 1/2 receptor antagonist for the treatment of insomnia.

We investigated the metabolism and disposition of vornorexant, a novel dual orexin receptor antagonist, in rats and dogs, and clarified invitro metabolite profiles in humans. Furthermore, we investigated the pharmacokinetics of active metabolites in rats and dogs and their CNS distribution in rats to elucidate its contribution to drug efficacy. [14 C]vornorexant was rapidly and mostly absorbed after the oral administration in rats and dogs. The drug-derived radioactivity, including metabolites, was distributed to major organs such as the liver, kidneys in rats, and was almost eliminated within 24 h post-dose in both species. Metabolite profiling revealed that main clearance mechanism of vornorexant was metabolism via multiple pathways by oxidation. The major circulating components were the cleaved metabolites (M10, M12) in rats, and the unchanged form in dogs, followed by M1, and then M3. Incubation with human hepatocytes resulted in formation of metabolites, including M1, M3, M10, and M12. The metabolic pathways were similar in all tested species. Resulting from the PK and CNS distribution of active metabolites (M1 and M3) with weaker pharmacological activity, the concentration of the unchanged form was higher than that of active metabolites in rat CSF and dog plasma, suggesting that the unchanged form mainly contributed to the drug efficacy. These findings demonstrate that vornorexant is absorbed immediately after administration, and vornorexant and its metabolites are rapidly and completely eliminated in rats and dogs. Thus, vornorexant may have favorable pharmacokinetic profiles as a hypnotic drug to provide rapid onset of action and minimal next-day residual effects in humans.

Kynurenine Metabolites in CSF and Plasma in Healthy Males.

In recent years, kynurenine metabolites generated by tryptophan catabolism have gained increasing attention in the context of brain diseases. The question of importance is whether there is a relationship between peripheral and central levels of these metabolites. Some of these compounds do not cross the blood-brain barrier; in particular, kynurenic acid, and most analyses of kynurenines from psychiatric patients have been performed using plasma samples. In the present study, we recruited 30 healthy volunteers with no history of psychiatric or neurological diagnosis, to analyze tryptophan, kynurenine, kynurenic acid, and quinolinic acid levels in CSF and plasma. In addition, kynurenic acid was analyzed in urine. The most important finding of this study is that CSF kynurenic acid levels do not correlate with those in plasma or urine. However, we found a correlation between plasma kynurenine and CSF kynurenic acid. Further, plasma kynurenine and plasma quinolinic acid were correlated. Our findings clarify the distribution of tryptophan and its metabolites in various body compartments and may serve as a guide for the analysis of these metabolites in humans. The most significant finding of the present study is that a prediction of brain kynurenic acid by of the analysis of the compound in plasma cannot be made.

TREM2 AD risk variants impact pTau and microglia and astrocyte related biomarkers in cognitively unimpaired subjects

AbstractBackgroundIn the central nervous system, Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) is expressed primarily in microglia. TREM2 receptors are important for microglial functions including phagocytosis, lipid metabolism and inflammatory responses. TREM2 coding variants (e.g. R47H rs75932628 and R62H rs143332484) increase the risk of late onset Alzheimer’s Diseases (AD). However, the impact of TREM2 risk variants on microglial cell functions in humans remains to be elucidated.MethodCSF and plasma samples were collected from AD patients (n = 120) and cognitively unimpaired control subjects (n = 53) with subjective complaints who do not meet biomarker‐based criteria for AD diagnosis. TREM2 AD risk variant carriers (n = 52) were screened from over 6000 samples of the Amsterdam dementia cohort using a combination of genotype array and exome sequencing. We performed extensive biomarker analysis of CSF and plasma samples with multidisciplinary approaches. We compared the effect of TREM2 mutations on AD disease and microglial and astrocytic biomarkers in AD patients and in cognitively unimpaired control subjects, respectively. A linear model was used with age and gender adjusted for the data analysis.ResultWe found higher levels of pTau181 and pTau231 in CSF and plasma in cognitively unimpaired TREM2 mutation carriers compared to non‐carriers, while no difference was observed between TREM2 genotype among the AD patients. Microglia and astrocyte biomarkers including sTREM2, FABP3, OLR1, YKL40 and GFAP were higher in the CSF from cognitively unimpaired TREM2 mutation carriers compared to non‐carriers, but no difference was detected between TREM2 genotype among the AD patients. We also found different levels of lipid metabolites in CSF and plasma samples from the TREM2 mutation carriers compared to non‐carriers in both AD patients and cognitively unimpaired control subjects.ConclusionTREM2 AD risk variants in cognitively unimpaired subjects increase pTau biomarkers and microglial and astrocytic related biomarkers. In AD patients, the biomarker differences between TREM2 genotype are diminished likely due to the extensive microglial responses to AD pathology. Moreover, our data indicates TREM2 AD risk variants may impact lipid‐metabolic processes in microglial cells. These data provide the biomarker insights on how TREM2 mutations may increase the risk of AD.

Kinetics of CSF metabolites profile after anti-tubercular treatment in TBM patients

Kinetics of CSF metabolites profile after anti-tubercular treatment in TBM patients

Impaired glucose utilization in the brain of patients with delirium following hip fracture.

Alterations in brain energy metabolism have long been proposed as one of several neurobiological processes contributing to delirium. This is supported by previous findings of altered CSF lactate and neuron-specific enolase concentrations and decreased glucose uptake on brain-PET in patients with delirium. Despite this, there are limited data on metabolic alterations found in CSF samples, and targeted metabolic profiling of CSF metabolites involved in energy metabolism has not been performed. The aim of the study was to investigate whether metabolites related to energy metabolism in the serum and CSF of patients with hip fracture are associated with delirium. The study cohort included 406 patients with a mean age of 81 years (standard deviation 10 years), acutely admitted to hospital for surgical repair of a hip fracture. Delirium was assessed daily until the fifth postoperative day. CSF was collected from all 406 participants at the onset of spinal anaesthesia, and serum samples were drawn concurrently from 213 participants. Glucose and lactate in CSF were measured using amperometry, whereas plasma glucose was measured in the clinical laboratory using enzymatic photometry. Serum and CSF concentrations of the branched-chain amino acids, 3-hydroxyisobutyric acid, acetoacetate and β-hydroxybutyrate were measured using gas chromatography-tandem mass spectrometry (GC-MS/MS). In total, 224 (55%) patients developed delirium pre- or postoperatively. Ketone body concentrations (acetoacetate, β-hydroxybutyrate) and branched-chain amino acids were significantly elevated in the CSF but not in serum among patients with delirium, despite no group differences in glucose concentrations. The level of 3-hydroxyisobutyric acid was significantly elevated in both CSF and serum. An elevation of CSF lactate during delirium was explained by age and comorbidity. Our data suggest that altered glucose utilization and a shift to ketone body metabolism occurs in the brain during delirium.

Prevalence of DDC genotypes in patients with aromatic L-amino acid decarboxylase (AADC) deficiency and in silico prediction of structural protein changes.

Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare autosomal recessive genetic disorder affecting the biosynthesis of dopamine, a precursor of both norepinephrine and epinephrine, and serotonin. Diagnosis is based on the analysis of CSF or plasma metabolites, AADC activity in plasma and genetic testing for variants in the DDC gene. The exact prevalence of AADC deficiency, the number of patients, and the variant and genotype prevalence are not known. Here, we present the DDC variant (n=143) and genotype (n=151) prevalence of 348 patients with AADC deficiency, 121 of whom were previously not reported. In addition, we report 26 new DDC variants, classify them according to the ACMG/AMP/ACGS recommendations for pathogenicity and score them based on the predicted structural effect. The splice variant c.714+4A>T, with a founder effect in Taiwan and China, was the most common variant (allele frequency=32.4%), and c.[714+4A>T];[714+4A>T] was the most common genotype (genotype frequency=21.3%). Approximately 90% of genotypes had variants classified as pathogenic or likely pathogenic, while 7% had one VUS allele and 3% had two VUS alleles. Only one benign variant was reported. Homozygous and compound heterozygous genotypes were interpreted in terms of AADC protein and categorized as: i) devoid of full-length AADC, ii) bearing one type of AADC homodimeric variant or iii) producing an AADC protein population composed of two homodimeric and one heterodimeric variant. Based on structural features, a score was attributed for all homodimers, and a tentative prediction was advanced for the heterodimer. Almost all AADC protein variants were pathogenic or likely pathogenic.

CSF neopterin and quinolinic acid are biomarkers of neuroinflammation and neurotoxicity in FIRES and other infection-triggered encephalopathy syndromes.

Infection-triggered encephalopathy syndromes (ITES) are potentially devastating neuroinflammatory conditions. Although some ITES syndromes have recognisable MRI neuroimaging phenotypes, there are otherwise few biomarkers of disease. Early detection to enable immune modulatory treatments could improve outcomes. We measured CSF neopterin, quinolinic acid, kynurenine and kynurenine/tryptophan ratio using a liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) system. The CSF of 18 children with ITES were compared with acute encephalitis (n = 20), and three control groups, namely epilepsy (n = 20), status epilepticus (n = 18) and neurogenetic controls (n = 20). The main ITES phenotypes in 18 patients were acute encephalopathy with biphasic seizures and late restricted diffusion (AESD, n = 4), febrile infection-related epilepsy syndrome (FIRES n = 4) and other ITES phenotypes. Influenza A was the most common infectious trigger (n = 5), and 50% of patients had a preceding notable neurodevelopmental or family history. CSF neopterin, quinolinic acid and kynurenine were elevated in ITES group compared to the three control groups (all p < 0.0002). The ROC (area under curve) for CSF neopterin (99.3%, CI 98.1-100) was significantly better than CSF pleocytosis (87.3% CI 76.4-98.2) (p = 0.028). Elevated CSF neopterin could discriminate ITES from other causes of seizures, status epilepticus and febrile status epilepticus (all p < 0.0002). The elevated CSF metabolites normalised during longitudinal testing in two patients with FIRES. CSF neopterin and quinolinic acid are neuroinflammatory and excitotoxic metabolites. This CSF metabolomic inflammatory panel can discriminate ITES from other causes of new onset seizures or status epilepticus, and rapid results (4 h) may facilitate early immune modulatory therapy.

Chapter 11 - Laboratory and metabolic investigations

Clinical variability and substantial overlap between mitochondrial disorders and other genetic disorders and inborn errors make the clinical and metabolic diagnosis of mitochondrial disorders quite challenging. Evaluating specific laboratory markers is essential in the diagnostic process, but mitochondrial disease can be present in the absence of any abnormal metabolic markers. In this chapter, we share the current consensus guidelines for metabolic investigations, including investigations in blood, urine, and the cerebral spinal fluid and discuss different diagnostic approaches. As personal experience might significantly vary and there are different recommendations published as diagnostic guidelines, the Mitochondrial Medicine Society developed a consensus approach based on literature review for metabolic diagnostics in a suspected mitochondrial disease. According to the guidelines, the work-up should include the assessment of complete blood count, creatine phosphokinase, transaminases, albumin, postprandial lactate and pyruvate (lactate/pyruvate ratio when the lactate level is elevated), uric acid, thymidine, amino acids, acylcarnitines in blood, and urinary organic acids (especially screening for 3-methylglutaconic acid). Urine amino acid analysis is recommended in mitochondrial tubulopathies. CSF metabolite analysis (lactate, pyruvate, amino acids, and 5-methyltetrahydrofolate) should be included in the presence of central nervous system disease. We also suggest a diagnostic strategy based on the mitochondrial disease criteria (MDC) scoring system in mitochondrial disease diagnostics; evaluating muscle-, neurologic-, and multisystem involvement, and the presence of metabolic markers and abnormal imaging. The consensus guideline encourages a primary genetic approach in diagnostics and only suggests a more invasive diagnostic approach with tissue biopsies (histology, OXPHOS measurements, etc.) after nonconclusive genetic testing.

Assessing the Biological Mechanisms linking Smoking Behavior and Alzheimer’s Disease: Mediation Analysis of Metabolomic Data

AbstractBackgroundSmoking is the most significant preventable health hazard in the modern world. It increases the risk of vascular problems, which are also risk factors for dementia. In addition, toxins in cigarettes increase oxidative stress and inflammation, which also have both been linked to the development of Alzheimer’s disease and related dementias (ADRD). However, the molecular mechanisms between smoking and ADRD are not well established. This study characterized these mechanisms using metabolomics data from the Wisconsin Registry for Alzheimer’s Prevention (WRAP).MethodsBased on 1,266 people who enrolled in WRAP and had the necessary data to assess whether the smoking‐cognitive function relationship is mediated by CSF or plasma metabolites, we broke down our analyses into four steps, based on the product method (Figure 1). The associations between smoking status and cognitive functions, smoking and metabolites, and metabolites and cognitive functions were assessed. All models were adjusted for age, sex, race, education level, CES‐D score, body mass index, and weekly alcohol consumption. The outcomes were Preclinical Alzheimer Cognitive Composite III (PACC3) and composite scores for Immediate Learning, Delayed Recall, and Executive Function. Mediation analyses were then implemented, and the mediation effect of metabolites was computed to explore the role of metabolites in smoking‐cognitive function pathways. False discovery rate (&lt;0.05) were applied as criteria for each step and 95% confidence intervals were used to verify the statistical significance for the metabolites that satisfied criteria.ResultsSix plasma metabolites were associated with smoking status and cognitive composite scores. Among them, N‐acetylneuraminate was significantly associated with PACC3 [95% confidence interval (CI): 0.00051‐0.01504] and Immediate Learning [95% CI: 0.00098‐0.01846] and was a significant mediator of the association between smoking status and these cognitive composites. The proportion of the total effect that was mediated by N‐acetylneuraminate was 12% for PACC3 and 13% for Immediate Learning.ConclusionsAs a mediator, N‐acetylneuraminate contributes to the association between smoking status and cognitive function. Interestingly, N‐Acetylneuraminate is a sialic acid and sialic acids have been found to be involved in several major changes associated with AD. For example, the CD33 sialic acid‐binding domain confers protection for late‐onset Alzheimer’s disease.

Nuclear Magnetic Resonance Spectroscopy Metabolomics in Idiopathic Intracranial Hypertension to Identify Markers of Disease and Headache.

We evaluated the metabolomic profile in the CSF, serum, and urine of participants with idiopathic intracranial hypertension (IIH) compared with that in controls and measured changes in metabolism associated with clinical markers of disease activity and treatment. A case-control study compared women aged 18-55 years with active IIH (Friedman diagnostic criteria) with a sex-matched, age-matched, and body mass index-matched control group. IIH participants were identified from neurology and ophthalmology clinics from National Health Service hospitals and underwent a prospective intervention to induce disease remission through weight loss with reevaluation at 12 months. Clinical assessments included lumbar puncture, headache, papilledema, and visual measurements. Spectra of the CSF, serum, and urine metabolites were acquired using proton nuclear magnetic resonance spectroscopy. Urea was lower in IIH participants (CSF, controls median ± IQR 0.196 ± 0.008, IIH 0.058 ± 0.059, p < 0.001; urine, controls 5971.370 ± 3021.831, IIH 4691.363 ± 1955.774, p = 0.009), correlated with ICP (urine p = 0.019) and headache severity (CSF p = 0.031), and increased by 12 months (CSF 12 months; 0.175 ± 0.043, p = 0.004, urine; 5210.874 ± 1825.302, p = 0.043). The lactate:pyruvate ratio was increased in IIH participants compared with that in controls (CSF, controls 49.739 ± 19.523, IIH 113.114 ± 117.298, p = 0.023; serum, controls 38.187 ± 13.392, IIH 54.547 ± 18.471, p = 0.004) and decreased at 12 months (CSF, 113.114 ± 117.298, p < 0.001). Baseline acetate was higher in IIH participants (CSF, controls 0.128 ± 0.041, IIH 0.192 ± 0.151, p = 0.008), correlated with headache severity (p = 0.030) and headache disability (p = 0.003), and was reduced at 12 months (0.160 ± 0.060, p = 0.007). Ketones, 3-hydroxybutyrate and acetoacetate, were altered in the CSF at baseline in IIH participants (3-hydroxybutyrate, controls 0.074 ± 0.063, IIH 0.049 ± 0.055, p = 0.019; acetoacetate, controls 0.013 ± 0.007, IIH 0.017 ± 0.010, p = 0.013) and normalized at 12 months (0.112 ± 0.114, p = 0.019, 0.029 ± 0.017, p = 0.015, respectively). We observed metabolic disturbances that are evident in the CSF, serum, and urine of IIH participants, suggesting global metabolic dysregulation. Altered ketone body metabolites normalized after therapeutic weight loss. CSF:serum urea ratio was altered, which may influence ICP dynamics and headache. Elevated CSF acetate, known to stimulate trigeminal sensitization, was associated with headache morbidity. These alterations of metabolic pathways specific to IIH provide biological insight and warrant mechanistic evaluation. Registered on ClinicalTrials.gov, NCT02124486 (submitted April 22, 2014) and NCT02017444 (submitted December 16, 2013).

Development of a translational inflammation panel for the quantification of cerebrospinal fluid Pterin, Tryptophan-Kynurenine and Nitric oxide pathway metabolites

SummaryBackgroundNeuroinflammatory diseases such as encephalitis, meningitis, multiple sclerosis and other neurological diseases with inflammatory components, have demonstrated a need for diagnostic biomarkers to define treatable and reversible neuroinflammation. The development and clinical validation of a targeted translational inflammation panel using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) could provide early diagnosis, rapid treatment and insights into neuroinflammatory mechanisms.MethodsAn inflammation panel of 13 metabolites (neopterin, tryptophan, kynurenine, kynurenic acid, 3-hydroxykynurenine, xanthurenic acid, anthranilic acid, 3-hydroxyanthranilic acid, quinolinic acid, picolinic acid, arginine, citrulline and methylhistamine) was measured based on a simple precipitation and filtration method using minimal CSF volume. The chromatographic separation was achieved using the Acquity UPLC BEH C18 column in combination with a gradient elution within a 12-min time frame. Acute encephalitis (n=10; myelin oligodendrocyte glycoprotein encephalitis n=3, anti-N-methyl-D-aspartate encephalitis n=2, acute disseminated encephalomyelitis n=2, herpes simplex encephalitis n=1, enteroviral encephalitis n=1) and frequency-matched non-inflammatory neurological disease controls (n=10) were examined.FindingsThe method exhibited good sensitivity as the limits of quantification ranged between 0.75 and 3.00 ng mL−1, good linearity (r2 > 0.99), acceptable matrix effects (<± 19.4%) and high recoveries (89.8-109.1 %). There were no interferences observed from common endogenous CSF metabolites, no carryover and concordance with well-established clinical methods. The accuracy and precision for all analytes were within tolerances, at <± 15 mean relative error and < 15 % coefficient of variation respectively. All analytes in matrix-matched pooled human CSF calibrators and human CSF extracts were stable for 24 h after extraction and two freeze-thaw cycles.InterpretationThe method was successfully applied to a pilot study investigating acute brain inflammation case-control groups. Statistical discrimination between encephalitis (n=10) and control groups (n=10) was achieved using orthogonal partial least squares discriminant analysis and heatmap cluster analysis. Statistical analysis of the measured metabolites identified significant alterations of seven metabolites in the tryptophan-kynurenine pathway (tryptophan, kynurenine, kynurenic acid, 3-hydroxykynurenine, anthranilic acid, 3-hydroxyanthranilic acid, quinolinic acid), arginine and neopterin in presence of acute neuroinflammation. Furthermore, elevated ratios of CSF kynurenine/tryptophan ratio, quinolinic acid/kynurenic acid and anthranilic acid/3-hydroxyanthranilic acid provided strong discriminative power for neuroinflammatory conditions. Studies of large groups of neurological diseases are required to explore the sensitivity and specificity of the inflammation panel.FundingFinancial support for the study was granted by Dale NHMRC Investigator grant APP1193648, Petre Foundation, Cerebral Palsy Alliance and Department of Biochemistry at the Children's Hospital at Westmead.

Elevated Free Phosphatidylcholine Levels in Cerebrospinal Fluid Distinguish Bacterial from Viral CNS Infections.

The identification of CSF biomarkers for bacterial meningitis can potentially improve diagnosis and understanding of pathogenesis, and the differentiation from viral CNS infections is of particular clinical importance. Considering that substantial changes in CSF metabolites in CNS infections have recently been demonstrated, we compared concentrations of 188 metabolites in CSF samples from patients with bacterial meningitis (n = 32), viral meningitis/encephalitis (n = 34), and noninflamed controls (n = 66). Metabolite reprogramming in bacterial meningitis was greatest among phosphatidylcholines, and concentrations of all 54 phosphatidylcholines were significantly (p = 1.2 × 10−25–1.5 × 10−4) higher than in controls. Indeed, all biomarkers for bacterial meningitis vs. viral meningitis/encephalitis with an AUC ≥ 0.86 (ROC curve analysis) were phosphatidylcholines. Four of the five most accurate (AUC ≥ 0.9) phosphatidylcholine biomarkers had higher sensitivity and negative predictive values than CSF lactate or cell count. Concentrations of the 10 most accurate phosphatidylcholine biomarkers were lower in meningitis due to opportunistic pathogens than in meningitis due to typical meningitis pathogens, and they correlated most strongly with parameters reflecting blood–CSF barrier dysfunction and CSF lactate (r = 0.73–0.82), less so with CSF cell count, and not with blood CRP. In contrast to the elevated phosphatidylcholine concentrations in CSF, serum concentrations remained relatively unchanged. Taken together, these results suggest that increased free CSF phosphatidylcholines are sensitive biomarkers for bacterial meningitis and do not merely reflect inflammation but are associated with local disease and a shift in CNS metabolism.

Longitudinal Analysis of Multiple Neurotransmitter Metabolites in Cerebrospinal Fluid in Early Parkinson's Disease.

ABSTRACTBackgroundCerebrospinal fluid (CSF) levels of monoamine metabolites may represent biomarkers of Parkinson's disease (PD).ObjectiveThe aim of this study was quantification of multiple metabolites in CSF from PD versus healthy control subjects (HCs), including longitudinal analysis.MethodsAbsolute levels of multiple monoamine metabolites in CSF were quantified by liquid chromatography coupled with tandem mass spectrometry from 161 individuals with early PD and 115 HCs from the Parkinson's Progression Marker Initiative and de novo PD (DeNoPA) studies.ResultsBaseline levels of homovanillic acid (HVA) and 3,4‐dihydroxyphenylacetic acid (DOPAC) were lower in individuals with PD compared with HCs. HVA levels correlated with Movement Disorder Society Unified Parkinson's Disease Rating Scale total scores (P < 0.01). Both HVA/dopamine and DOPAC/dopamine levels correlated with caudate nucleus and raw DOPAC with putamen dopamine transporter single‐photon emission computed tomography uptake ratios (P < 0.01). No metabolite changed over 2 years in drug‐naive individuals, but some changed on starting levodopa treatment.ConclusionsHVA and DOPAC CSF levels mirrored nigrostriatal pathway damage, confirming the central role of dopaminergic degeneration in early PD. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

MBRS-56. RE-EVALUATION OF LEPTOMENINGEAL METASTASIS IN MEDULLOBLASTOMA WITH MAGNETIC RESONANCE IMAGING, RELATED SYMPTOMS AND CEREBROSPINAL FLUID METABOLOMIC PROFILES

BACKGROUNDDiagnosis of leptomeningeal metastasis (LM) in medulloblastoma is made by positive findings in either MRI or CSF cytology. We studied if CSF metabolomics profile can differentiate the discordant results between MRI and CSF cytology and reflect the sampling time related to treatment.MATERIALS AND METHODSWe prospectively collected 83 CSF samples from 45 medulloblastoma patients. A total of 6,527 low-mass ions (LMIs) were detected using liquid chromatography tandem mass spectrometry (LC-MS/MS). Discriminative low-mass ions (LMIs) between four different MRI and cytology results groups were evaluated and representative LMIs were identified.RESULTSCSF cytology and MRI finding were both positive for LM in 8 samples and both negative for 47 samples. Tests were cytology (-) and MRI (+) in 20 samples, whereas cytology (+) and MRI (-) status were in the remaining 8 samples. The diagnostic accuracy by area under the curve (AUC) was 0.722 for cytology and 0.888 for MRI each. Based on the exclusiveness of LMI between groups, we verified 27 discriminative LMIs in MRI (+)/ cytology (+), 9 LMIs in MRI (+)/ cytology (-), and 12 LMIs in MRI (-) and cytology (+) group, separately. Metabolic pathways involved in MRI (+)/ cytology (+) group were linoleic acid, phenylalanine, TCA cycle, retinol, arginine-ornithine, nicotinate-nicotinamide, etc. Low-mass-ion discriminant equation (LOME), which could differentiate both different MRI and cytology results and the sampling time or presence of LM-related symptoms was found.CONCLUSIONNon-targeted MSanalysis CSF metabolite in medulloblastomas revealed significantly different profiles, and these results suggest LMI profiles might have a higher sensitivity for LM diagnosis than either MRI or cytology.

Age and cognitive diagnosis influence cerebrospinal fluid ketone levels after a triglyceride infusion in older adults

AbstractBackgroundKetone bodies and diets which increase plasma ketones are being investigated for treatments for Alzheimer’s disease (AD), but little is known about what influences ketone body levels in the brain.MethodOlder adults (n=21, age 67.7 ± 8.6) underwent a 5‐hour TG and saline infusion on different days in random crossover design; CSF was collected at the end of the infusion. Targeted aqueous metabolites were measured using Shimadzu Nexera 20/AB‐Sciex 6500 Triple Quadrupole Liquid Chromatography‐Mass Spectroscopy which targets 216 metabolites representing over 35 different metabolic pathways. Data were analyzed using MetaboAnalyst 4.0 and SAS.ResultOf 216 possible metabolites, 99 were detectable in the CSF, with an average of 88 metabolites per sample which did not differ by treatment (saline 87.6 ± 1.4, TG 87.7 ± 1.7). Three metabolites significantly differed by treatment: 3‐hydroxybutyrate (HBA), glutamic acid and methylguanosine (Table). The top hit HBA further differed by cognitive diagnosis. Fasting HBA was similar for both groups but TG‐induced increases in HBA were over 3 times higher for those with cognitive impairment (change score normal control 9.8 uM ± 8.3, cog impair 32.4 uM ±7.4, p value log transformed levels 0.0198). None of the metabolites in Table differed by APOE status or by sex. Age positively correlated with fasting HBA whereas systolic blood pressure and fasting glucose positively correlated with TG HBA and HBA change score. Fasting lipid levels did not predict fasting or TG‐induced HBA.ConclusionWe detected metabolites in human CSF, and most metabolites did not change after a TG infusion. The top metabolite was the ketone body HBA, and levels were influenced by age, cognitive diagnosis, and markers of the metabolic syndrome. These results suggest that interventions that increase plasma ketones may lead to higher brain ketones in groups at risk for AD.

Approach to Patients with Neurometabolic Diseases Who Show Characteristic Signs and Symptoms.

Neurometabolic disorders are hereditary conditions mainly affect the function of the brain and the nervous system. The prevalence of these disorders is 1 in 1,000 live births. Such disorders, at different ages, could manifest as sepsis, hypoglycemia, and other neurologic disorders. Having similar manifestations leads to delayed diagnosis of neurometabolic disorders. A number of neurometabolic disorders have known treatments; however, to prevent long-term complications the key factors are early diagnosis and treatment. Although a large number of neurometabolic diseases have no treatment or cure, the correct and on-time diagnosis before death is important for parents to have plans for prenatal diagnosis. Different diagnostic procedures could be offered to parents, enzymatic procedures, and determining metabolites in plasma, urine, and CSF, and molecular genetic diagnosis. Molecular genetic diagnostic procedures are expensive and could not be offered to all parents. Therefore, we aimed to design algorithms to diagnose neurometabolic disorders according to some frequent and characteristic signs and symptoms. By designing these algorithms and using them properly, we could offer diagnostic enzymatic panels. These enzymatic panels are inexpensive; thereby reducing the financial burden on the parents. Also, having an early diagnosis according to these panels could lead to offering more accurate and less expensive molecular genetic tests.

Denial of food to the hungry rat: A novel paradigm for induction and evaluation of anger-like emotion

BackgroundAnger is one of the primary emotions that profoundly impacts our daily life. Although the neural basis of anger needs to be explored on high priority, the field has not sufficiently advanced, perhaps due to the lack of a suitable animal model. New methodWe fabricated arenas in which the hungry rat can see and smell food but can not consume it. These animals seemed hyperactive and we monitored the (a) motor activity to access food, (b) biting behaviour, (c) blood pressure, heart rate and nor-epinephrine (NE) in plasma, (d) 5-HT and its metabolite in CSF, (e) effect of diazepam, 5-HT agonist, and antagonist on the behaviour, and (f) expression of immediate early gene in discrete areas of the brain. ResultsThe fasted animal frantically tries to acquire food. It engages in intense biting of the separator plate; the behaviour was considered as an expression of anger-like emotion. These behaviours were attenuated following pre-treatment with diazepam, fluoxetine (both ip) or 5-HT1A receptor agonist (icv), but potentiated by 5-HT1A antagonist (icv). Concomitantly, an increase in the blood pressure, heart rate and NE in plasma, but a decrease in 5-HT and 5-HIAA in the CSF was noted. The animals showed activation of neuronal c-Fos in different brain areas compared to fasted or refed controls. Comparison with existing methodsA novel animal paradigm for assessment of anger. ConclusionsThe protocol enables us to generate and evaluate anger-like responses in rat and permits insights into the neurological basis of anger.