Human Cerebral Spinal Fluid Research Articles

Quantification of nine antiretroviral drugs in cerebrospinal fluid: An approach to overcome sample collection tube adsorption

A highly sensitive LC-MS/MS methods were developed and validated to quantify nine antiretrovirals (atazanavir [ATV], tenofovir [TFV], emtricitabine [FTC], darunavir [DRV], dolutegravir [DTG], efavirenz [EFV], lamivudine [3TC], raltegravir [RAL], and ritonavir [RTV]) in human cerebral spinal fluid (CSF). The approach remedies adsorption issues caused by polypropylene based sample collection tubes. 1% ammonium hydroxide in methanol was added in an amount equal to the volume of each quality control (QC) or patient sample. Protein precipitation was utilized with a CSF sample volume of 100 μL and a 100 μL of methanol:ACN and vortexed. Chromatographic separation was achieved with a 3 × 100 ACE® C18 column for ATV, DRV, DTG, EFV, RTV and RAL, and a 2 × 100 Polar RP column for TFV/FTC/3TC. Mobile phase was methanol:water:formic acid (70:30:0.1, v/v/v) for ATV, DRV, DTG, EFV and RTV (10 uL injection, flow rate: 1.00 mL/min), ACN:water:formic acid (35:65:0.1, v/v/v) for RAL (50 uL injection, flow rate: 1.00 mL/min), ACN:water:formic acid (2:98:0.1, v/v/v) for TFV, FTC and 3TC (50 uL injection, flow rate: 0.35 mL/min). Column temperature was 40° C across all assays. The mass spectrometer was operated in positive, multiple-reaction-monitoring (MRM) mode with electrospray ionization (ESI) for all analytes with the exception of EFV, which was operated in negative, MRM mode with ESI. The assay was linear over the calibration range of 1 to 250 ng/mL for all analytes. The addition of 1% ammonium hydroxide in sample tubes overcame up to 44% negative bias in QC samples and allowed the methods to meet full validation criteria.

In situ electrodeposition of bismuth oxide nanowires @MWNT on the carbon fiber microelectrode for the sensitively electrochemical detection of folic acid

A microminiaturized electrochemical device, BiO@CNW/CFE was fabricated based on the in situ co-electrodeposition of bismuth oxide nanowires (BiNWs) and multi-walled carbon nanotubes (MWNTs) on the surface of carbon fiber electrode (CFE). The nanostructure of BiNWs could bind MWNTs on the surface of CFE during the precipitation of bismuth at the potential of −1.1 V. The vimineous nanostructure of BiO@CNW improved the surface area and electrochemical activity of the microelectrode. With the low background noise, folic acid (FA) can be detected sensitively by BiO@CNW/CFE based on the electrochemical reduction via the method of square wave voltammetry. The linear range of FA in sodium acetate-acetic acid buffer was achieved in the range of 5.00 nM–200 nM, the detection limit was estimated to be 0.63 nM. The recoveries of FA in human serum and artificial cerebral spinal fluid were between 99% and 103%, which indicates BiO@CNW/CFE was a reliable sensor for the detection of FA in biological samples.

Influence of sleep disruption on protein accumulation in neurodegenerative diseases

Abnormal accumulation of disease proteins in the central nervous system is a neuropathological feature in neurodegenerative disorders. Recently, a growing body of evidence has supported a role of disruption of the sleep-wake cycle in disease development, pathological changes and abnormal protein accumulation in neurodegenerative diseases, especially in Alzheimer’s disease and Parkinson’s disease. Sleep deprivation promotes abnormal accumulation of disease proteins. Interestingly, amyloid-β (Aβ) has daily oscillations in human cerebral spinal fluid (CSF) and is cleared more in sleep. Both circadian genes and circadian hormones are associated with disease protein deposition. Recently, the glymphatic pathway and meningeal lymphatics have been shown to play a critical role in Aβ clearance, which is mediated by the aquaporin (AQP-4) water channel on astrocytes. The rate of the clearance of Aβ by the glymphatic pathway is different during the sleep/wake cycle. Most importantly, circadian rhythms facilitate glymphatic clearance of solutes and Aβ in the CSF and interstitial fluid in an AQP-4-dependent manner, which further provides evidence for the involvement of circadian rhythms in disease protein clearance.

Analysis of Brain Protein Stability Changes in Mouse Models of Normal Aging and α-Synucleinopathy Reveals Age- and Disease-Related Differences.

Here, we utilize the stability of proteins from rates of oxidation (SPROX) technique, to profile the thermodynamic stabilities of proteins in brain tissue cell lysates from Huα-Syn(A53T) transgenic mice at three time points including at 1 month (n = 9), at 6 months (n = 7), and at the time (between 9 and 16 months) a mouse became symptomatic (n = 8). The thermodynamic stability profiles generated here on 332 proteins were compared to thermodynamic stability profiles generated on the same proteins from similarly aged wild-type mice using a two-way unbalanced analysis of variance (ANOVA) analysis. This analysis identified a group of 22 proteins with age-related protein stability changes and a group of 11 proteins that were differentially stabilized in the Huα-Syn(A53T) transgenic mouse model. A total of 9 of the 11 proteins identified here with disease-related stability changes have been previously detected in human cerebral spinal fluid and thus have potential utility as biomarkers of Parkinson's disease (PD). The differential stability observed for one protein, glutamate decarboxylase 2 (Gad2), with an age-related change in stability, was consistent with the differential presence of a known, age-related truncation product of this protein, which is shown here to have a higher folding stability than full-length Gad2. Mass spectrometry data were deposited at ProteomeXchange (PXD016985).

The Meninges Enhance Acute Lymphoblastic Leukemia Chemoresistance in the Central Nervous System

▪Central nervous system (CNS) relapse is a principal cause of treatment failure among pediatric patients with acute lymphoblastic leukemia (ALL). Furthermore, available CNS-directed therapies are associated with significant short and long-term morbidities. While extensive research has demonstrated a critical role of the bone marrow microenvironment in leukemia biology, how the CNS regulates ALL survival and chemoresistance has yet to be fully determined.To identify where leukemia cells home within the CNS, we transplanted multiple human leukemia cell lines into immune-compromised mice. After systemic leukemia development that included the CNS, the mice were euthanized, fixed, and examined by histopathology and immunohistochemistry. We identified both the meninges and, to a lesser extent, the choroid plexus as the predominant CNS sites that harbor leukemia cells both before and after treatment with systemic cytarabine (Figure 1A).In contrast, parenchymal involvement by leukemia was a rare, and often late, finding.This pattern of CNS involvement by leukemia also recapitulates the histopathology of human CNS leukemia.We then used ex vivo co-culture approaches to focus more specifically on the effects of the meninges on leukemia biology. We found that leukemia cells adhered to meningeal cells in a co-culture system that can substitute human cerebral spinal fluid for tissue culture media. Moreover, co-cultured leukemia cells were significantly more resistant to cytarabine-induced apoptosis, as measured by annexin-V staining, relative to the same leukemia cells grown in suspension or adherent to either fibronectin-treated plates or a neural precursor cell line (Figure 1B). Extending these results, meningeal-mediated leukemia chemoresistance was also observed with methotrexate as well as when measured by caspase 3/7 & 8 activity and mitochondrial polarization by TMRE staining. Moreover, primary ALL cells exhibited significantly increased apoptosis when cultured in suspension relative to when co-cultured with primary meningeal cells (60.4% vs. 8.9%, P <0.0001), further supporting the pro-survival effect of meningeal cells on leukemia cells. Finally, while leukemia cells co-cultured with meningeal cells exhibited striking chemoresistance, leukemia cells cultured in meningeal conditioned media also exhibited moderate chemoresistance (Figure 1B). Together, these results suggest that both a mechanism dependent upon direct cell contact and a soluble factor(s) secreted by meningeal cells contribute to meningeal-mediated leukemia chemoresistance.In order to better understand the mechanism of meningeal-mediated leukemia chemoresistance, we examined the effect of co-culture on the apoptosis pathway in leukemia cells. An apoptosis antibodyarray showed changes in the expression of multiple apoptosis family proteins (including caspase 3, caspase 8, Bax, Bad, BID, BIM, BCL-2, SMAC and survivin) in leukemia cells co-cultured with meningeal cells relative to leukemia cells in suspension. However, assessing how the dynamic levels, activities, and complex interactions of these and other BCL-2 family of pro-and anti-apoptotic proteins (BH3 proteins) integrate to regulate the overall apoptotic balance is experimentally challenging. To address this issue, we utilized a functional apoptosis assay, BH3 profiling, which predicts cellular responses to stimuli based on measuring the response of mitochondria to perturbation by a panel of BH3 domain peptides. BH3 profiling of leukemia cells in suspension or co-cultured with meningeal cells showed that leukemia cells co-cultured with meningeal cells are significantly less primed to undergo apoptosis relative to leukemia cells in suspension.In summary, these results show that the meninges provide a unique CNS leukemia niche that regulates the apoptotic balance in leukemia cells in order to enhance leukemia chemoresistance and contribute to relapse. This work also suggests that CNS leukemia persistence and relapse is not only related to poor penetration of some chemotherapy agents across the blood-brain barrier and into the CNS. Further characterization of the cellular and molecular mechanisms of meningeal-mediated leukemia chemoresistance will provide new insights into the pathophysiology of CNS leukemia as well as inform novel therapeutic strategies to target leukemia cells in the CNS niche. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

High-Throughput Liquid-Liquid Extractions with Nanoliter Volumes.

Current methods for liquid-liquid extractions generally require microliter to milliliter volumes of solvents and sample, long equilibration times, and manual procedures. Extraction methods for samples in microfluidic systems have been limited as this tool is difficult to implement on the nanoliter or smaller scale. We have developed slug-flow nanoextraction (SFNE), a method based on droplet microfluidics that allows multiple liquid-liquid extractions to be performed simultaneously in a capillary tube, using only 5 nL of sample and extraction solvent per extraction. Each two-phase slug is segmented from the others by immiscible carrier fluid. We found rapid extractions (<5 s), partition coefficients matching those achieved at larger scale extractions, and potential to preconcentrate samples through volume manipulation. This method was used to accurately and rapidly determine octanol-water partition coefficients (Kow), determining identical Kow as the shake-flask method for acetaminophen, Kow = 2.48 ± 0.02. The measurement, along with calibration and 12 replicates, was complete within 5 min, consuming under 150 nL of solvent and sample. The method was also applied to extract analytes from complex biological samples prior to electrospray ionization-tandem mass spectrometry (ESI-MS/MS) at a rate of 6 s per sample, allowing for simultaneous determination of five different drugs spiked into human plasma, synthetic urine (SU), and artificial cerebral spinal fluid (aCSF) using ethyl acetate as the extraction phase. The signal-to-noise (S/N) for analytes improved up to 19-fold compared to direct ESI-MS of single-phase droplets (aqueous plugs segmented by carrier fluid), with limits of detection down to 7 nM (35 amol).

Simultaneous Quantitation of S(+)- and R(-)-Baclofen and Its Metabolite in Human Plasma and Cerebrospinal Fluid using LC-APCI-MS/MS: An Application for Clinical Studies.

Baclofen is a racemic mixture that is commonly used for the treatment for spasticity. However, the optimal dose and dosing interval to achieve effective cerebral spinal fluid (CSF) concentrations of baclofen are not known. Moreover, it is unclear if there are differences in the ability of R- or S-baclofen to cross the blood–brain barrier and achieve effective CSF concentrations. We have validated a liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method with improved selectivity and sensitivity for the simultaneous quantitation of R- and S-baclofen and metabolites in plasma and CSF. Protein precipitation by acetonitrile was utilized to obtain an acceptable recovery of the analytes. The detection and separation of analytes was achieved on a 48 °C-heated Crownpak CR(+) column (150 mm × 4.0 mm, 5μ) with elution using 0.4% formic acid (FA) in water and 0.4% FA in acetonitrile as the mobile phase running at a flow rate of 1.0 mL/min. Accurate quantitation was assured by using this MS/MS method with atmospheric pressure chemical ionization in multiple reaction monitoring (MRM) mode. Therefore, this method is enantioselective, accurate, precise, sensitive, reliable, and linear from 1 to 1500 ng/mL for baclofen and 2 to 4000 ng/mL for the metabolites. An additional method was developed to separate racemic baclofen 3-(4-chlorophenyl)-4 hydroxybutyric acid metabolites for individual concentration determination. Both validated methods were successfully applied to a clinical pharmacokinetic human plasma and CSF study evaluating the disposition of baclofen and metabolites.

Distinct Antibody Repertoire of Cerebral Spinal Fluid B Cells from Healthy Controls

Abstract Antibodies have been implicated in the pathogenesis of several neuropsychiatric diseases. Although these disease-associated antibodies typically circulate (eg, Sydenham’s Chorea), they can arise from autoreactive B cells in situ, located within the central nervous system itself (eg, Multiple Sclerosis). Although normal human cerebral spinal fluid (CSF) has been classically considered to be acellular, the presence of B cells in CSF from healthy controls has been reported (Ho et al. 2013, Kleine 2015). In order to provide context in elucidating the pathophysiology of autoreactive B cells in disease, we questioned the origin of CSF B cells in healthy donors. Specifically, we asked whether CSF B cells represent a distinct population (select subset), or a random assortment, of peripheral B cells in the same individual. We obtained paired samples of CSF and peripheral blood (PB) from 4 healthy control volunteers. B cells were isolated by immunofluorescent staining and cell sorting, followed by immunoglobulin amplification and sequencing. We confirmed that each normal CSF sample contained small numbers of B cells. We found highly significant differences in V-D-J usage of immunoglobulin from these B cells as compared to V-D-J usage of matched PB B cells, with significance determined by Chi-square goodness of fit, confirmed by resampling-based permutation tests. These results indicate that B cells are selected for entry into, or persistence in, the central nervous system, and are not simply a random reflection of B cells circulating at any given time. This suggests the value of examining the repertoire of CSF B cells that may be pathogenic agents in neuropsychiatric diseases whose origin remains obscure, such as schizophrenia.

Glycosaminoglycans in human cerebrospinal fluid determined by LC-MS/MS MRM

Glycosaminoglycans (GAGs) were recovered from human cerebral spinal fluid (CSF) and after their conversion to disaccharides using polysaccharide lyases were analyzed by liquid chromatography tandem mass spectrometry using multiple reaction monitoring. CSF showed ng/mL levels of heparan sulfate, chondroitin sulfates and hyaluronan. The amounts and disaccharide composition of these GAGs differed from those found in human plasma. This approach may offer a new method for the discovery of biomarkers for diseases of the central nervous system.

Analytics of Cerebrospinal Fluid MicroRNA Quantitative PCR Studies

MicroRNAs (miRNAs) are small non-coding RNAs that regulate post-transcriptional gene expression. Recent studies have shown that human disease states correlate with measurable differences in the level of circulating miRNAs relative to healthy controls. Thus, there is great interest in developing clinical miRNA assays as diagnostic or prognostic biomarkers for diseases, and as surrogate measures for therapeutic outcomes. Our studies have focused on miRNAs in human cerebral spinal fluid (CSF) as biomarkers for central nervous system (CNS) diseases. Our objective here was to examine factors that may affect the outcome of quantitative PCR (qPCR) studies on CSF miRNAs, in order to guide planning and interpretation of future CSF miRNA TaqMan® low-density array (TLDA) studies. We obtained CSF from neurologically normal (control) donors and used TLDAs to measure miRNA expression. We examined sources of error in the TLDA outcomes due to (1) nonspecific amplification of products in total RNA, (2) variations in RNA isolations performed on different days, (3) miRNA primer probe efficiency, and (4) variations in individual TLDA cards. We also examined the utility of card-to-card TLDA corrections and use of an unchanged "reference standard" to remove batch processing effects in large-scale studies.

Primary Human Microglia Are Phagocytically Active and Respond to Borrelia burgdorferi With Upregulation of Chemokines and Cytokines.

The Lyme disease causing bacterium Borrelia burgdorferi has an affinity for the central nervous system (CNS) and has been isolated from human cerebral spinal fluid by 18 days following Ixodes scapularis tick bite. Signaling from resident immune cells of the CNS could enhance CNS penetration by B. burgdorferi and activated immune cells through the blood brain barrier resulting in multiple neurological complications, collectively termed neuroborreliosis. The ensuing symptoms of neurological impairment likely arise from a glial-driven, host inflammatory response to B. burgdorferi. To date, however, the mechanism by which the bacterium initiates neuroinflammation leading to neural dysfunction remains unclear. We hypothesized that dead B. burgdorferi and bacterial debris persist in the CNS in spite of antibiotic treatment and contribute to the continuing inflammatory response in the CNS. To test our hypothesis, cultures of primary human microglia were incubated with live, antibiotic-killed and antibiotic-killed sonicated B. burgdorferi to define the response of microglia to different forms of the bacterium. We demonstrate that primary human microglia treated with B. burgdorferi show increased expression of pattern recognition receptors and genes known to be involved with cytoskeletal rearrangement and phagocytosis including MARCO, SCARB1, PLA2, PLD2, CD14, and TLR3. In addition, we observed increased expression and secretion of pro-inflammatory mediators and neurotrophic factors such as IL-6, IL-8, CXCL-1, and CXCL-10. Our data also indicate that B. burgdorferi interacts with the cell surface of primary human microglia and may be internalized following this initial interaction. Furthermore, our results indicate that dead and sonicated forms of B. burgdorferi induce a significantly larger inflammatory response than live bacteria. Our results support our hypothesis and provide evidence that microglia contribute to the damaging inflammatory events associated with neuroborreliosis.

Simultaneous detection of reduced and oxidized forms of coenzyme Q10 in human cerebral spinal fluid as a potential marker of oxidative stress.

The redox balance of coenzyme Q10 in human plasma is a good marker of oxidative stress because the reduced form of coenzyme Q10 (ubiquinol-10) is very sensitive to oxidation and is quantitatively converted to its oxidized form (ubiquinone-10). Here we describe an HPLC method for simultaneous detection of ubiquinol-10 and ubiquinone-10 in human cerebral spinal fluid to meet a recent demand for measuring local oxidative stress. Since the levels of coenzyme Q10 in human cerebral spinal fluid are less than 1/500 of those in human plasma, cerebral spinal fluid extracted with 2-propanol requires concentration for electrochemical detection. Using human plasma diluted 500-fold with physiological saline as a pseudo-cerebral spinal fluid, we found that addition of tert-butylhydroquinone was effective in preventing the oxidation of ubiquinol-10. The optimized tert-butylhydroquinone concentration in the extraction solvent was 20 µM. The addition of 20 µM ascorbic acid or co-addition of tert-butylhydroquinone and ascorbic acid (20 µM each) were also effective in preventing the oxidation of ubiquinol-10, but ascorbic acid alone gave poor reproducibility. Good within day reproducibility was observed, and day-to-day analytical variance was excellent.

The Central Nervous System Microenvironment Influences the Leukemia Transcriptome and Enhances Leukemia Chemo-Resistance

Central nervous system (CNS) relapse is a significant cause of treatment failure among patients with acute lymphoblastic leukemia (ALL). Isolated CNS relapse occurs in ~3-8% of children with leukemia and accounts for 30-40% of initial relapses in some clinical trials. In addition, CNS-directed therapies are associated with seizures, secondary neoplasms, encephalopathy, and long-term endocrine, developmental, neurovascular, and cognitive deficits. While many studies have demonstrated that interactions between leukemia cells and components of the bone marrow microenvironment influence leukemia development, maintenance, and chemo-resistance, the role of the CNS microenvironment in leukemia is less well studied.To investigate the influence of the CNS niche in leukemia, we asked whether the CNS niche could impart unique and functionally important gene expression changes in leukemia cells. We transplanted NALM-6 human, pre-B leukemia cells into NSG mice without prior irradiation to avoid perturbing the bone marrow and CNS niches. After systemic leukemia development the mice were euthanized and leukemia cells were isolated from the bone marrow and CNS microenvironments. Gene expression profiling of ~700 cancer-associated genes (NanoString® Technology) identified 36 leukemia genes differentially expressed (30 up-regulated and 6 down-regulated; fold change ≥ 2 and FDR<0.05) in leukemia cells in the CNS microenvironment relative to the bone marrow. Furthermore, functional annotation revealed the up-regulated genes were involved in known leukemia and cancer pathways including MAPK, RAS, and apoptosis.We elected to further examine the gene PBX1 as it is a transcription factor with known roles in hematopoiesis, leukemia, and cancer biology. PBX1 contributes to Evi-1 mediated leukemia development in a murine model of leukemia and is a partner with TCF3 in the t(1;19) translocation that occurs in ~5% of pre-B ALL. Interestingly, this translocation is also associated with an increased risk for CNS relapse. We confirmed PBX1 mRNA up-regulation in leukemia cells either isolated from the CNS or in leukemia cells co-cultured with CNS-derived, murine choroid plexus cells by quantitative PCR. Supporting the generalizability of these results, additional human B-cell leukemia lines SEM and REH also exhibited PBX1 mRNA up-regulation in leukemia cells isolated from the murine CNS niche. Western blots of NALM-6 and SEM leukemia cells isolated from the mouse CNS as well as from leukemia cells co-cultured ex vivo with choroid plexus cells also showed PBX1 up-regulation at the protein level. Finally, culture of leukemia cells in either choroid plexus cell conditioned media or human cerebral spinal fluid (CSF) had minimal effects on PBX1 protein levels, suggesting that direct cell contact, rather than a soluble factor(s), contributes to PBX1 up-regulation in leukemia cells.Following confirmation of PBX1 up-regulation in leukemia cells within the CNS microenvironment, we next ectopically expressed PBX1, or GFP as a control, in leukemia cells to identify functional consequences of PBX1 expression in leukemia cells. Leukemia cells expressing PBX1 exhibited decreased sensitivity to cytarabine relative to control cells as measured by both proliferation and apoptosis assays. Furthermore, shRNA targeting PBX1, but not control shRNA, prevented PBX1 up-regulation in leukemia cells when co-cultured with choroid plexus cells and modestly, but significantly, attenuated the ability of choroid plexus cells to protect leukemia cells from cyatabine-induced apoptosis. Finally, although PBX1 had no effect on leukemia proliferation, it caused enhanced colony-forming ability in semi-solid media, consistent with increased leukemia self-renewal properties. Together these results suggest PBX1 up-regulation in leukemia cells may contribute to both leukemia self-renewal properties and chemo-resistance in the CNS niche.In summary, we believe this work illustrates the unique and functionally important effect that the CNS microenvironment has on leukemia cells. More comprehensive analyses of the leukemia transcriptome, genome, and proteome in the CNS niche will build upon this foundation and provide a more detailed understanding of the role of the CNS niche in leukemia biology. Finally, this approach may identify targetable CNS niche-mediated mechanisms of leukemia chemo-resistance and self-renewal. DisclosuresNo relevant conflicts of interest to declare.

Microfluidic Chip with Molecular Beacons Detects miRNAs in Human CSF to Reliably Characterize CNS-specific Disorders

RNA profiling in biofluids holds promise as both diagnostic and prognostic markers. High expression levels of distinctive cell free circulating miRNAs in serum, plasma and cerebral spinal fluid (CSF), have been utilized as classifiers to detect and characterize disorders of the central nervous system (CNS). We formulated the quantitative theory showing how the results of surprisal analysis enable a reliable inference if tumor cells are present in the sample from a single measurement. Subsequently, we develop a molecular beacon-based microfluidic chip that enables for fluorescence detection of miRNAs without amplification in low volumes of human CSF. Using surprisal analysis, we identified a miRNA classifier that enables high fidelity detection and characterization of human brain tumors. We anticipate that this micro-fluidic platform will provide a critical translational tool with point of care potential for CNS disorders.

Influence of surface modification and static pressure on microdialysis protein extraction efficiency.

There is growing interest in using microdialysis (MD) for monitoring larger and more complex molecules such as neuropeptides and proteins. This promotes the use of MD membranes with molecular weight cut off (MWCO) of 100 kDa or above. The hydrodynamic property of the membrane goes to ultrafiltration or beyond, making the MD catheters more sensitive to pressure. In the meantime, despite the large pore size, studies have shown that membrane biofouling still lead to unstable catheter performance. The objective is to study in vitro how 500 kDa dextran and Poloxamer 407 surface modification affect the fluid recovery (FR) and extraction efficiency (EE) of 100 kDa MWCO MD catheters. A pressure chamber was designed to facilitate the tests, using as MD sample a protein standard with similar concentrations as in human cerebral spinal fluid, comparing native and Poloxamer 407 modified MD catheters. The collected dialysate fractions were examined for FR and protein EE, employing Dot-it Spot-it Protein Assay for total protein EE and targeted mass spectrometry (MS) for EE of individual proteins and peptides. The FR results suggested that the surface modified catheters were less sensitive to the pressure and provide higher precision, and provided a FR closer to 100%. The surface modification did not show a significant effect on the protein EE. The average total protein EE of surface modified catheters was slightly higher than that of the native ones. The MS EE data of individual proteins showed a clear trend of complex response in EE with pressure.

Mass spectrometric analysis of rat cerebrospinal fluid proteins following exposure to the neurotoxicant carbonyl sulfide.

Using a proteomic-based approach we have investigated possible altered expression of a range of cerebral spinal fluid (CSF) proteins following exposure to the neurotoxicant carbonyl sulfide (COS). CSF is ideal for the investigation of markers of brain injury or disease since it is secreted from several central nervous system structures and changes in the CSF composition may reflect brain insult and many pathological processes. Animals were placed in exposure chambers and were exposed to 0 ppm or 500 ppm COS for 1, 2 or 3 days, 6 h per day. After the last inhalation exposure, 50-70 μL CSF sample was obtained by lumbar puncture. CSF samples were analyzed by electrospray ionization mass spectrometry (ESI-MS) on either a Premier quadrupole time-of-flight (QTOF) or an Agilent 6340 ion trap and by matrix-assisted laser desorption/ionization (MALDI)-MS on a 4800 MALDI-TOF/TOF analyzer. The dynamic range of abundance of the identified proteins spanned over more than three orders of magnitude. The four most abundant proteins identified (albumin, cystatin C, serotransferrin, transthyretin) are major proteins that are present in both CSF and blood at high levels but the fifth most abundant protein identified (prostaglandin H2D isomerase) is the second most abundant protein in human CSF and is secreted and synthesized in the rat central nervous system. No significant differences were observed between COS-treated CSF samples and the control CSF samples because of blood contamination. Quantitative MS protein analyses of rat CSF is limited by the low sample volumes that can practicably be obtained from rats and the low protein concentrations in rat CSF. Results of this work suggest a clear need for CSF collection that would minimize blood contamination. Published in 2014. This article is a U.S. Government work and is in the public domain in the USA.

A reference laboratory experience of clinically achievable voriconazole, posaconazole, and itraconazole concentrations within the bloodstream and cerebral spinal fluid.

Interest in antifungal therapeutic-drug monitoring has increased due to studies demonstrating associations between concentrations and outcomes. We reviewed the antifungal drug concentration database at our institution to gain a better understanding of achievable triazole drug levels. Antifungal concentrations were measured by high-performance liquid chromatography (HPLC), ultraperformance liquid chromatography and single-quadrupole mass spectrometry (UPLC/MS), or a bioassay. For this study, only confirmed human bloodstream (serum or plasma) and cerebral spinal fluid (CSF) concentrations of voriconazole, posaconazole, and itraconazole were analyzed. The largest numbers of bloodstream and CSF samples were found for voriconazole (14,370 and 173, respectively). Voriconazole bloodstream concentrations within the range of 1 to 5.5 μg/ml represented 50.6% of samples. Levels below the lower limit of quantification (0.2 μg/ml) were observed in 14.6% of samples, and 10.4% of samples had levels of ≥5.5 μg/ml. CSF voriconazole levels ranged from undetectable to 15.3 μg/ml and were <0.2 μg/ml in 11% of samples. Posaconazole bloodstream concentrations were ≥0.7 and ≥1.25 μg/ml in 41.6% and 18.9% of samples, respectively. Posaconazole was detected in only 4 of 22 CSF samples (undetectable to 0.56 μg/ml). Itraconazole levels, as measured by UPLC/MS, were ≥0.5 μg/ml in 43.3% and were undetectable in 33.9% of bloodstream samples. In contrast, when measured by a bioassay, itraconazole/hydroxyitraconazole bloodstream concentrations were ≥1.0 μg/ml in 72.9% of samples and were undetectable in 18% of samples. These results indicate that there is marked variability in bloodstream concentrations achieved with these three azoles. In addition, many levels within the bloodstream for each azole and for voriconazole and posaconazole in the CSF were undetectable or below thresholds associated with efficacy.

SOD1 in Cerebral Spinal Fluid as a Pharmacodynamic Marker for Antisense Oligonucleotide Therapy

Therapies designed to decrease the level of SOD1 are currently in a clinical trial for patients with superoxide dismutase (SOD1)-linked familial amyotrophic lateral sclerosis (ALS). To determine whether the SOD1 protein in cerebral spinal fluid (CSF) may be a pharmacodynamic marker for antisense oligonucleotide therapy and a disease marker for ALS. Antisense oligonucleotides targeting human SOD1 were administered to rats expressing SOD1G93A. The human SOD1 protein levels were measured in the rats' brain and CSF samples. In human CSF samples, the following proteins were measured: SOD1, tau, phosphorylated tau, VILIP-1, and YKL-40. Ninety-three participants with ALS, 88 healthy controls, and 89 controls with a neurological disease (55 with dementia of the Alzheimer type, 19 with multiple sclerosis, and 15 with peripheral neuropathy). Antisense oligonucleotide-treated SOD1G93A rats had decreased human SOD1 messenger RNA levels (mean [SD] decrease of 69% [4%]) and decreased protein levels (mean [SD] decrease of 48% [14%]) in the brain. The rats' CSF samples showed a similar decrease in hSOD1 levels (mean [SD] decrease of 42% [14%]). In human CSF samples, the SOD1 levels varied a mean (SD) 7.1% (5.7%) after additional measurements, separated by months, were performed. The CSF SOD1 levels were higher in the participants with ALS (mean [SE] level, 172 [8] ng/mL; P<.05) and the controls with a neurological disease (mean [SE] level, 172 [6] ng/mL; P<.05) than in the healthy controls (mean [SE] level, 134 [4] ng/mL). Elevated CSF SOD1 levels did not correlate with disease characteristics in participants with ALS or controls with dementia of the Alzheimer type, but they did correlate with tau, phosphorylated tau, VILIP-1 and YKL-40 levels in controls with dementia of the Alzheimer type. SOD1 in CSF may be an excellent pharmacodynamic marker for SOD1-lowering therapies because antisense oligonucleotide therapy lowers protein levels in the rat brain and rat CSF samples and because SOD1 levels in CSF samples from humans are stable over time.

Multi-platform characterization of the human cerebrospinal fluid metabolome: a comprehensive and quantitative update.

BackgroundHuman cerebral spinal fluid (CSF) is known to be a rich source of small molecule biomarkers for neurological and neurodegenerative diseases. In 2007, we conducted a comprehensive metabolomic study and performed a detailed literature review on metabolites that could be detected (via metabolomics or other techniques) in CSF. A total of 308 detectable metabolites were identified, of which only 23% were shown to be routinely identifiable or quantifiable with the metabolomics technologies available at that time. The continuing advancement in analytical technologies along with the growing interest in CSF metabolomics has led us to re-visit the human CSF metabolome and to re-assess both its size and the level of coverage than can be achieved with today's technologies.MethodsWe used five analytical platforms, including nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), direct flow injection-mass spectrometry (DFI-MS/MS) and inductively coupled plasma-mass spectrometry (ICP-MS) to perform quantitative metabolomics on multiple human CSF samples. This experimental work was complemented with an extensive literature review to acquire additional information on reported CSF compounds, their concentrations and their disease associations.ResultsNMR, GC-MS and LC-MS methods allowed the identification and quantification of 70 CSF metabolites (as previously reported). DFI-MS/MS allowed the quantification of 78 metabolites (6 acylcarnitines, 13 amino acids, hexose, 42 phosphatidylcholines, 2 lyso-phosphatidylcholines and 14 sphingolipids), while ICP-MS provided quantitative results for 33 metal ions in CSF. Literature analysis led to the identification of 57 more metabolites. In total, 476 compounds have now been confirmed to exist in human CSF.ConclusionsThe use of improved metabolomic and other analytical techniques has led to a 54% increase in the known size of the human CSF metabolome over the past 5 years. Commonly available metabolomic methods, when combined, can now routinely identify and quantify 36% of the 'detectable' human CSF metabolome. Our experimental works measured 78 new metabolites that, as per our knowledge, have not been reported to be present in human CSF. An updated CSF metabolome database containing the complete set of 476 human CSF compounds, their concentrations, related literature references and links to their known disease associations is freely available at the CSF metabolome database.

Membrane-type Matrix Metalloproteinase-3 Regulates Neuronal Responsiveness to Myelin through Nogo-66 Receptor 1 Cleavage

Nogo-66 receptor 1 (NgR1) is a glycosylphosphatidylinositol-anchored receptor for myelin-associated inhibitors that restricts plasticity and axonal regrowth in the CNS. NgR1 is cleaved from the cell surface of SH-SY5Y neuroblastoma cells in a metalloproteinase-dependent manner; however, the mechanism and physiological consequence of NgR1 shedding have not been explored. We now demonstrate that NgR1 is shed from multiple populations of primary neurons. Through a loss-of-function approach, we found that membrane-type matrix metalloproteinase-3 (MT3-MMP) regulates endogenous NgR1 shedding in primary neurons. Neuronal knockdown of MT3-MMP resulted in the accumulation of NgR1 at the cell surface and reduced the accumulation of the NgR1 cleavage fragment in medium conditioned by cortical neurons. Recombinant MT1-, MT2-, MT3-, and MT5-MMPs promoted NgR1 shedding from the surface of primary neurons, and this treatment rendered neurons resistant to myelin-associated inhibitors. Introduction of a cleavage-resistant form of NgR1 reconstitutes the neuronal response to these inhibitors, demonstrating that specific metalloproteinases attenuate neuronal responses to myelin in an NgR1-dependent manner.