Association of cigarette smoking with cerebrospinal fluid biomarkers of insulin sensitivity and neurodegeneration

INTRODUCTION

Cigarette smoking increases both the risk for insulin resistance and amyloid-β (Aβ) aggregation, and impaired brain insulin/insulin-like growth factor 1 (IGF1) signaling might increase risk factors for Alzheimer's disease (AD). We aimed to investigate the association among cerebrospinal fluid (CSF) insulin sensitivity/IGF1, glucose/lactate, and Aβ42 and further explore whether insulin sensitivity contributed to the risk for AD in active smokers.

METHODS

In this cross-sectional study, levels of insulin, IGF1, and lactate/glucose of 75 active smokers and 78 nonsmokers in CSF were measured. Three polymorphisms regulating IGF1 were genotyped. Analysis of variance was used to compare differences of variables between groups. Partial correlation was performed to test the relationship between CSF biomarkers and smoking status. General linear models were applied to test the interaction of the effect of single nucleotide polymorphisms and cigarette smoking on CSF IGF1 levels.

RESULTS

In the CSF from active smokers, IGF1 and lactate levels were significantly lower (p = .016 and p = .010, respectively), whereas Aβ42 (derived from our earlier research) and insulin levels were significantly higher (p < .001 and p = .022, respectively) as compared to the CSF from nonsmokers. The AG + GG genotype of rs6218 in active smokers had a significant effect on lower CSF IGF1 levels (p = .004) and lower CSF insulin levels in nonsmokers (p = .016).

CONCLUSIONS

Cigarette smoking as the "at-risk" factor for AD might be due to lower cerebral insulin sensitivity in CSF, and the subjects with rs6218G allele seem to be more susceptible to the neurodegenerative risks for cigarette smoking.

Cerebrospinal fluid analysis of metabolites is not correlated to microdialysis measurements in acute brain injured patients

BACKGROUND

Cerebral microdialysis (CMD) has become an established bedside monitoring modality but its implementation remains complex and costly and is therefore performed only in a few well-trained academic centers. This study investigated the relationship between cerebrospinal fluid (CSF) and CMD glucose and lactate concentrations.

METHODS

Two centers retrospective study of prospectively collected data. Consecutive adult (>18 years) acutely brain injured patients admitted to the Intensive Care Unit between 2010 and 2021 were eligible if CSF and CMD glucose and lactate concentrations were concomitantly measured at least once.

RESULTS

Of 113 patients being monitored with an external ventricular drainage and CMD, 49 patients (25 from Innsbruck and 24 from Brussels) were eligible for the final analysis, including a total of 96 measurements. Median CMD glucose and lactate concentrations were 1.15 (0.51-1.57) mmol/L and 3.44 (2.24-5.37) mmol/L, respectively; median CSF glucose and lactate concentrations were 4.67 (4.03-5.34) mmol/L and 3.40 (2.85-4.10) mmol/L, respectively. For the first measurements, no correlation between CSF and CMD glucose concentrations (R2 <0.01; p = 0.95) and CSF and CMD lactate concentrations (R2 =0.16; p = 0.09) was found. Considering all measurements, the repeated measure correlation analysis also showed no correlation for glucose (rrm = -0.01; 95% Confidence Intervals -0.306 to 0.281; p = 0.93) and lactate (rrm = -0.11; 95% Confidence Intervals -0.424 to 0.236; p = 0.55).

CONCLUSIONS

In this study including acute brain injured patients, no correlation between CSF and brain tissue measurements of glucose and lactate was observed. As such, CSF measurements of such metabolites cannot replace CMD findings.

D-Glucose uptake and clearance in the tauopathy Alzheimer's disease mouse brain detected by on-resonance variable delay multiple pulse MRI

In this study, we applied on-resonance variable delay multiple pulse (onVDMP) MRI to study D-glucose uptake in a mouse model of Alzheimer's disease (AD) tauopathy and demonstrated its feasibility in discriminating AD mice from wild-type mice. The D-glucose uptake in the cortex of AD mice (1.70 ± 1.33%) was significantly reduced compared to that of wild-type mice (5.42 ± 0.70%, p = 0.0051). Also, a slower D-glucose uptake rate was found in the cerebrospinal fluid (CSF) of AD mice (0.08 ± 0.01 min-1) compared to their wild-type counterpart (0.56 ± 0.1 min-1, p < 0.001), which suggests the presence of an impaired glucose transporter on both blood-brain and blood-CSF barriers of these AD mice. Clearance of D-glucose was observed in the CSF of wild-type mice but not AD mice, which suggests dysfunction of the glymphatic system in the AD mice. The results in this study indicate that onVDMP MRI could be a cost-effective and widely available method for simultaneously evaluating glucose transporter and glymphatic function of AD. This study also suggests that tau protein affects the D-glucose uptake and glymphatic impairment in AD at a time point preceding neurofibrillary tangle pathology.

Cerebrospinal Fluid Analysis

Cerebrospinal fluid (CSF) analysis is a diagnostic tool for many conditions affecting the central nervous system. Urgent indications for lumbar puncture include suspected central nervous system infection or subarachnoid hemorrhage. CSF analysis is not necessarily diagnostic but can be useful in the evaluation of other neurologic conditions, such as spontaneous intracranial hypotension, idiopathic intracranial hypertension, multiple sclerosis, Guillain-Barré syndrome, and malignancy. Bacterial meningitis has a high mortality rate and characteristic effects on CSF white blood cell counts, CSF protein levels, and the CSF:serum glucose ratio. CSF culture can identify causative organisms and antibiotic sensitivities. Viral meningitis can present similarly to bacterial meningitis but usually has a low mortality rate. Adjunctive tests such as CSF lactate measurement, latex agglutination, and polymerase chain reaction testing can help differentiate between bacterial and viral causes of meningitis. Immunocompromised patients may have meningitis caused by tuberculosis, neurosyphilis, or fungal or parasitic infections. Subarachnoid hemorrhage has a high mortality rate, and rapid diagnosis is key to improve outcomes. Computed tomography of the head is nearly 100% sensitive for subarachnoid hemorrhage in the first six hours after symptom onset, but CSF analysis may be required if there is a delay in presentation or if imaging findings are equivocal. Xanthochromia and an elevated red blood cell count are characteristic CSF findings in patients with subarachnoid hemorrhage. Leptomeningeal carcinomatosis can mimic central nervous system infection. It has a poor prognosis, and large-volume CSF cytology is diagnostic.

Transient hypoglycorrhachia with paroxysmal abnormal eye movement in early infancy

Paroxysmal abnormal eye movement in early infancy is one of the initial symptoms of glucose transporter 1 deficiency syndrome (GLUT1DS). We describe four early infants with transient hypoglycorrhachia presenting with abnormal eye movements. Their symptoms disappeared after the introduction of a ketogenic diet (KD), and their development was normal. Since no variants in SLC2A1 were detected, the CSF-to-blood glucose ratios (C/B) were re-examined, and within normal range. None of the four patients displayed recurrent symptoms after withdrawal from the KD. Because long-term KD has potential adverse effects and could affect the quality of life of patients and their families, re-examination of CSF glucose during late infancy should be considered in the case of absence of the SLC2A1 pathogenic variant.

Self-Assembled Au Nanoparticle Arrays for Precise Metabolic Assay of Cerebrospinal Fluid

Precise and rapid monitoring of metabolites in biofluids is a desirable but unmet goal for disease diagnosis and management. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) exhibits advantages in metabolite analysis. However, the low accuracy in quantification of the technique limits its transformation to clinical usage. We report herein the use of Au nanoparticle arrays self-assembled at liquid-liquid interfaces for mass spectrometry (MS)-based quantitative biofluids metabolic profiling. The two-dimensional arrays feature uniformly and closely packed Au nanoparticles with 3 nm interparticle gaps. The experimental study and theoretical simulation show that the arrays exhibit high photothermal conversion and heat confinement effects, which enhance the laser desorption/ionization efficacy. With the nanoscale roughness, the AuNP arrays as laser desorption/ionization substrates can interrupt the coffee-ring effect during droplet evaporation. Therefore, high reproducibility (RSD <5%) is obtained, enabling accurate quantitative analysis of diverse metabolites from 1 μL of biofluids in seconds. By quantifying glucose in the cerebrospinal fluid (CSF), it allows us to identify patients with brain infection and rapidly evaluate the clinical therapy response. Consequently, the method shows potential in advanced metabolite analysis and biomedical diagnostics.

Diagnostic yield of capillary compared to venous glucose in the diagnosis of hypoglycorrhachia in children: A prospective, observational study

INTRODUCTION

The ratio of cerebrospinal fluid (CSF) glucose and blood glucose is of major relevance, conducting to the diagnosis of hypoglycorrhachia, which is a sign of neuroinfection, as well as a number of neurological diseases of genetic or neoplastic etiology. Glucose in capillary sample (glucometry) is a low cost, readily available technique, as compared to venous glucose. This study aims to compare glucometry to venous glucose in the diagnosis of hypoglycorrhachia in pediatric population.

METHODS

Prospective cross-sectional study based on data obtained from lumbar punctures in the period from February 2017 to January 2019 in a specialized pediatric institution in Colombia.

RESULTS

97 patients were analyzed, aged 1 month to 17 years old, mean 7.67 years, 52 (53.61%) were female. 26 (26.8%) were diagnosed with hypoglycorrhachia. Pearson correlation coefficient for absolute venous and capillary glucose was 0.54, and 0.55 for the ratios of CSF glucose/venous glucose and CSF glucose/glucometry, which support a linear correlation between the variables in both, absolute values and ratios. Intraclass correlation coefficient was calculated for both, the venous glucose and glucometry ratios, which was 0.52, revealing a moderate agreement among the tests. Sensitivity and specificity of CSF glucose/glucometry, as compared to gold standard are 73.1% and 60.6% respectively; whereas predictive positive value (PPV) and negative predictive value (NPV), were 40.4% and 86.0%.

CONCLUSION

Glucometry cannot replace the glucose in venous sample in the diagnosis of hypoglycorrhachia in children.

Effect of amylin on memory and central insulin resistance in a rat model of Alzheimer's disease

Context: Alzheimer's disease is strongly associated with brain insulin signalling.Objective: Investigating the effect of amylin as a novel treatment in streptozotocin (STZ) rat model of AD.Materials and methods: Alzheimer's disease (AD) was induced in albino rats by intracerebroventricular injection of STZ (3 mg/kg). Rats received either amylin analogue (Pramlintide 200 μg/kg/day) or Metformin (30 mg/kg/day) for 5 weeks.Results: Both Pramlintide and Metformin improve learning and memory through enhancing insulin signalling (p-IR and p-PI3K) which lead to lowering level of CSF glucose, phosphorylated tau proteins, and amyloid-β peptide (Aβ) in hippocampus.Conclusions: Insulin sensitisers as Metformin and Pramlintide can improve learning and memory and decrease the pathological changes in STZ induced rat model of AD. However, Pramlintide is superior to Metformin in some memory tests which related to its action as an amylin analogue. Amylin improves learning and memory through an independent effect other than insulin sensitisation.

Erratum: Sensitivity and specificity of cerebrospinal fluid glucose measurement by an amperometric glucometer

[No Abstract Available].

Comment on: Sensitivity and specificity of cerebrospinal fluid glucose measurement by an amperometric glucometer

[No Abstract Available].

Analysis of the Cerebrospinal Fluid at Point of Care in Resource-Limited Setting: A Pilot Study

BACKGROUND

In the face of an emergency, a decision on the need for a timely intervention must be made urgently especially when it has to do with the brain. This study was conducted to determine the usefulness of Urine combistix and glucometer as a "point of care" testing tool in the emergency analysis of cerebrospinal fluid (CSF) in resource-limited settings.

METHODOLOGY

In this pilot cross-sectional study, CSF and blood glucose were simultaneously measured using a point of care glucometer and central laboratory. The CSF protein, glucose, blood and leucocytes were also assessed using the urine combistix strips. The CSF/blood glucose ratios obtained at the bedside with a glucometer versus those obtained by the central laboratory were also compared.

RESULTS

Turn-around time for glucometer and Combistix analysis was 3.5minutes (3-4mins) versus 360minutes (300- 600minutes) for the laboratory. A strong correlation was observed amongst urine Combistix values for CSF protein, blood, leucocyte and glucose with those obtained from the laboratory (ROC of 0.875, sensitivity:75% and specificity: 100%). In addition, there was significant correlation of the CSF-blood glucose ratios from both the laboratory versus glucometer.

CONCLUSION

This pilot study showed that a combination of Combistix analysis for CSF protein, glucose, blood and leucocyte values plus a glucometer analysis of CSF and blood glucose can serve as a reliable and accurate synergistic means for early diagnosis of CSF abnormalities particularly in patients suspected to have meningitis. Finally, it provides a template on which an accurate CSF diagnostic kit can be developed.

Sensitivity and specificity of cerebrospinal fluid glucose measurement by an amperometric glucometer

Objectives:

To provide more data regarding the role of an amperometric glucometer in diagnosing meningitis.

Methods:

This is a prospective study conducted at the Pediatric and Neonatology Department, Qatif Central Hospital, Qatif, Saudi Arabia between March 2017 and September 2018. We measured glucose concentrations in cerebrospinal fluid (CSF) and blood using a central laboratory and amperometric glucometer (AG). We compared CSF/blood glucose ratios obtained in a central laboratory from clinical bedside examination with a glucometer, and calculated the sensitivity and specificity for detecting cases of meningitis.

Results:

A total of 101 patients with clinical suspicion of meningitis were recruited for CSF sampling. Of 101 CSF samples, 61 (60%) were suggestive of meningitis. Of 101 samples, 47 had hypoglycorrhachia identified by a standard laboratory, and 17% of them were also detected by AG. The correlation between CSF/blood glucose by AG and laboratory ratios was substantial (r=0.894, p<0.01, 95% CI: 0.805-0.983). The AG sensitivity was 100% and specificity was 55% in pediatric cases, while in neonates the sensitivity was 86% and the specificity was 26%.

Conclusion:

Amperometric glucometers can be used to detect hypoglycorrhachia accurately. This point-of-care testing tool is easily accessible and can be used by health care providers for cases suspected of meningitis.

Comparison of Cerebrospinal Fluid Biomarkers for Differential Diagnosis of Acute Bacterial and Viral Meningitis with Atypical Cerebrospinal Fluid Characteristics

OBJECTIVE

Several cerebrospinal fluid (CSF) biomarkers are used to distinguish between acute bacterial meningitis (BM) and viral meningitis (VM). We compared the ability of lactate and glucose (GL) in CSF and the CSF/blood GL ratio to distinguish between acute BM and VM with typical and atypical CSF characteristics.

METHODS

Three hundred and twenty-four CSF reports were included, which were distributed as the acute BM, VM, and normal control groups (n = 63, 139, and 122, respectively).

RESULTS

Lactate level in the CSF of acute BM group was 4-fold higher than that in the acute VM and control groups (p < 0.0001). CSF lactate presented higher specificity (92%) and negative predictive value (94%) compared to CSF GL and CSF/blood GL ratio in distinguishing acute BM and VM. Definitive acute BM or VM with atypical CSF cell characteristics was observed in 23.2 and 21.6% of samples, respectively, and these groups showed reduced performance of characteristics of all CSF biomarkers. CSF lactate showed better operational characteristics than those of CSF GL and CSF/blood GL ratio, presenting the highest positive likelihood ratio, and thus aided in the differential diagnosis of VM with atypical CSF.

CONCLUSION

The CSF lactate assay can be routinely used in laboratories as a rapid, automated, and easy method that is independent of lactate blood levels.

[Very low cerebral glucose level despite normal systemic glucose level in a patient with subarachnoid haemorrhage]

In this case report, data are presented from a patient, who suffered from a severe subarachnoid haemorrhage and was admitted to the neuro-intensive care unit, where the use of cerebral microdialysis (CMD) allowed the detection of a severe mismatch between cerebral and systemic glucose levels and compromised cerebral metabolism despite systemic glucose values within the normal range. The established CMD monitoring allowed subsequent titration of insulin respecting acceptable cerebral and systemic glucose levels.

Accuracy of Using a Point-of-Care Glucometer for Cerebrospinal Fluid Glucose Screening in Resource-Limited Countries

OBJECTIVES

To explore the accuracy of using a point-of-care (POC) glucometer for cerebrospinal fluid (CSF) glucose screening.

METHODS

A cross-sectional study was conducted. A glucose analysis of CSF samples collected from infants <90 days with suspected meningitis was paired between tests by using a POC glucometer (POC-CSF glucose) and a laboratory glucose analysis (laboratory-CSF glucose). Accuracy and limits of agreement were compared, as well as the glucometer performance to detect a laboratory-CSF glucose level <45 and 60 mg/dL.

RESULTS

Seventy-three CSF samples were analyzed. Subjects' mean gestational age was 32.2 (SD 4.0) weeks, the mean weight was 1947.7 (SD 814.5) g, and the median age was 8 (interquartile range: 2 to 19.5) days. POC-CSF glucose levels ranged from 26 to 126 mg/dL. The mean (±1.96 SD) difference between POC-CSF and laboratory-CSF glucose levels was -1.6 (interquartile range: -12.6 to 9.4) mg/dL. A POC-CSF glucose level <45 mg/dL has a sensitivity and negative predictive value (NPV) to detect a laboratory-CSF glucose level <45 mg/dL of 82% and 94%, respectively. For a laboratory-CSF glucose level <60 mg/dL, a POC glucose level <60 mg/dL provides a sensitivity and NPV of 96% and 90%, respectively, whereas sensitivity and NPV reach 100% at a POC glucose level <70 mg/dL.

CONCLUSIONS

A POC glucometer for CSF glucose can detect a potential abnormal glucose level with an appropriate cutoff level. This may facilitate rapid decisions for empirical antibiotics in suspected meningitis, pending laboratory results in limited-resource settings, but requires robust validation in future studies before implementation.

Hypothermic neuroprotection during reperfusion following exposure to aglycemia in central white matter is mediated by acidification

Hypoglycemia is a common iatrogenic consequence of type 1 diabetes therapy that can lead to central nervous system injury and even death if untreated. In the absence of clinically effective neuroprotective drugs we sought to quantify the putative neuroprotective effects of imposing hypothermia during the reperfusion phase following aglycemic exposure to central white matter. Mouse optic nerves (MONs), central white matter tracts, were superfused with oxygenated artificial cerebrospinal fluid (aCSF) containing 10 mmol/L glucose at 37°C. The supramaximal compound action potential (CAP) was evoked and axon conduction was assessed as the CAP area. Extracellular lactate was measured using an enzyme biosensor. Exposure to aglycemia, simulated by omitting glucose from the aCSF, resulted in axon injury, quantified by electrophysiological recordings, electron microscopic analysis confirming axon damage, the extent of which was determined by the duration of aglycemia exposure. Hypothermia attenuated injury. Exposing MONs to hypothermia during reperfusion resulted in improved CAP recovery compared with control recovery measured at 37°C, an effect attenuated in alkaline aCSF. Hypothermia decreases pH implying that the hypothermic neuroprotection derives from interstitial acidification. These results have important clinical implications demonstrating that hypothermic intervention during reperfusion can improve recovery in central white matter following aglycemia.

A frame-shift deletion in the PURA gene associates with a new clinical finding: Hypoglycorrhachia. Is GLUT1 a new PURA target?

PURA is a DNA/RNA-binding protein known to have an important role as a transcriptional and translational regulator. Mutations in the PURA gene have been documented to cause mainly a neurologic phenotype including hypotonia, epilepsy, development delay and respiratory alterations. We report here a patient with a frame-shift deletion in the PURA gene that apart from the classical PURA deficiency phenotype had marked hypoglycorrhachia, overlapping the clinical findings with a GLUT1 deficiency syndrome. SLC2A1 (GLUT1) mutations were discarded, so we hypothesized that GLUT1 could be downregulated in this PURA deficient scenario. We confirmed reduced GLUT1 expression in the patient's peripheral blood cells compared to controls predicting that this could also be happening in the blood-brain barrier and in this way explain the hypoglycorrhachia. Based on PURA's known functions as a transcriptional and translational regulator, we propose GLUT1 as a new PURA target. Further in vitro and in vivo studies are needed to confirm this and to uncover the underlying molecular mechanisms.

Comprehensive analysis of patients with neuromyelitis optica spectrum disorder (NMOSD) combined with chronic hepatitis B (CHB) infection and seropositive for anti-aquaporin-4 antibody

Previous research indicated the association between hepatitis B virus (HBV) infection/vaccination and the onset of demyelinating diseases. However, most of these studies were single case reports, and comprehensive data are still scarce. Here we present a comprehensive analysis of 10 patients with neuromyelitis optica spectrum disorder (NMOSD) combined with chronic hepatitis B (CHB) infection and seropositive for anti-aquaporin-4 antibody (AQP4-Ab). Demographic, clinical, laboratory, neuroimaging, outcome, and follow-up data of the 10 patients were retrospectively analyzed. The median age at the onset of NMOSD was 35 years (range 25-43). Nine patients were female (90%). All patients were positive for HBsAg and had been diagnosed with CHB earlier than with NMOSD. One patient had an autoimmune disease. All patients had normal thyroid function. Paresthesia and visual impairment were the most common clinical symptoms. The cerebrospinal fluid (CSF) parameters (protein and glucose) were normal in 10 cases, whereas slightly higher CSF white blood cell count was detected in 3 patients. The brain and spinal cord magnetic resonance imaging findings were abnormal in 8 patients. All patients were treated with hormone and immunosuppressive therapy, and anti-HBV agents. Patients with detectable serum HBV DNA were more prone to liver damage after receiving high doses of corticosteroids. In 8 patients, the symptoms improved before they were discharged. Two patients with optic neuritis (ON) maintained the symptoms. A month later, 1/8 patient had recurrence of symptoms, and one ON patient progressed to NMO. Overall, the characteristics of NMOSD patients with CHB and seropositive for AQP4-Ab are usually nonspecific. Abnormal liver function test results in NMOSD patients should be a warning of possible CHB infection, and the treatment should be modified accordingly.

Evaluation of blood-brain barrier function by quotient alpha2 macroglobulin and its relationship with interleukin-6 and complement component 3 levels in neuropsychiatric systemic lupus erythematosus

Although quotient of alpha2 macroglobulin (Qα2MG) was previously reported to be useful for the evaluation of blood–brain barrier (BBB) function, it is not commonly used. We therefore evaluated BBB function among the various subsets of neuropsychiatric systemic lupus erythematosus (NPSLE) using quotient Q α2MG. Furthermore, we determined the correlation between Q α2MG and cerebrospinal (CSF) interleukin (IL)-6 level and quotient complement component 3 (Q C3). To determine intrathecal production of C3, the C3 index (Q C3/Q α2MG) was also calculated. Fifty-six patients with SLE were included in this study. Of these, 48 were diagnosed with NPSLE, consisting of 30 diffuse NPSLE patients (acute confusional state (ACS): n = 14, non-ACS: n = 16) and 18 patients with focal NPSLE. CSF IL-6 concentration, and paired serum and CSF levels of α2MG and C3, were measured by enzyme-linked immuno solvent assay (ELISA). The Q α2MG, Q C3, and C3 index were then calculated. Q α2MG, Q C3, and IL-6 concentrations in the CSF were significantly elevated in NPSLE compared with non-NPSLE. Among the subsets of NPSLE, significant increases in Q α2MG, CSF IL-6, and Q C3 were observed in ACS compared with non-ACS or focal NPSLE. There was a positive correlation between CSF IL-6 level and Q α2MG, as well as between Q C3 and Q α2MG, in diffuse NPSLE. There were no significant differences in C3 index between NPSLE and non-NPSLE, as well as among the subgroups of NPSLE. Our study suggests that BBB disruption is present in ACS, and elevated levels of IL-6 and C3 in CSF in diffuse NPSLE, especially in ACS, might result from their entry to the CSF from the systemic circulation through the damaged BBB, as well as increased intrathecal production. Furthermore, Q α2MG might be useful for the evaluation of BBB integrity.

The impact of ageing, fasting and high-fat diet on central and peripheral glucose tolerance and glucose-sensing neural networks in the arcuate nucleus

Obesity and ageing are risk factors for diabetes. In the present study, we investigated the effects of ageing, obesity and fasting on central and peripheral glucose tolerance and on glucose-sensing neuronal function in the arcuate nucleus of rats, with a view to providing insight into the central mechanisms regulating glucose homeostasis and how they change or are subject to dysfunction with ageing and obesity. We show that, following a glucose load, central glucose tolerance at the level of the cerebrospinal fluid (CSF) and plasma is significantly reduced in rats maintained on a high-fat diet (HFD). With ageing, up to 2 years, central glucose tolerance was impaired in an age-dependent manner, whereas peripheral glucose tolerance remained unaffected. Ageing-induced peripheral glucose intolerance was improved by a 24-hour fast, whereas central glucose tolerance was not corrected. Pre-wean, immature animals have elevated basal plasma glucose levels and a delayed increase in central glucose levels following peripheral glucose injection compared to mature animals. Electrophysiological recording techniques revealed an energy-status-dependent role for glucose-excited, inhibited and adapting neurones, along with glucose-induced changes in synaptic transmission. We conclude that ageing affects central glucose tolerance, whereas HFD profoundly affects central and peripheral glucose tolerance and, in addition, glucose-sensing neurones adapt function in an energy-status-dependent manner.

Metabolomic profiling of CSF in multiple sclerosis and neuromyelitis optica spectrum disorder by nuclear magnetic resonance

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are inflammatory diseases of the central nervous system. Although several studies have characterized the metabolome in the cerebrospinal fluid (CSF) from MS and NMOSD patients, comparative analyses between them and between the relapse and the remission of each disease have not been performed. Both univariate and multivariate analyses were used to compare 1H-NMR spectra of CSF from MS, NMOSD, and healthy controls (HCs). The statistical analysis showed alterations of eight metabolites that were dependent on the disease. Levels of 2-hydroxybutyrate, acetone, formate, and pyroglutamate were higher and levels of acetate and glucose were lower in both MS and NMOSD. Citrate was lower in MS patients, whereas lactate was higher in only NMOSD specifically. The shared feature of metabolic changes between MS and NMOSD may be related to altered energy metabolism and fatty acid biosynthesis in the brain. Another analysis to characterize relapse and remission status showed that isoleucine and valine were down-regulated in MS relapse compared to MS remission. The other metabolites identified in the disease comparison showed the same alterations regardless of disease activity. These findings would be helpful in understanding the biological background of these diseases, and distinguishing between MS and NMOSD, as well as determining the disease activity.

Increased cerebrospinal fluid levels of GABA, testosterone and estradiol in women with polycystic ovary syndrome

STUDY QUESTION

Do cerebrospinal fluid (CSF) concentrations of gamma-aminobutyric acid (GABA), testosterone (T) and estradiol (E2) differ in women with polycystic ovary syndrome (PCOS) as compared to eumenorrheic, ovulatory women (EW)?

SUMMARY ANSWER

Women with PCOS displayed higher CSF levels of GABA and E2, and possibly T, than EW.

WHAT IS KNOWN ALREADY

The chronic anovulation characteristic of PCOS has been attributed to increased central GnRH drive and resulting gonadotropin aberrations. Androgens are thought to regulate GABA, which in turn regulates the neural cascade that modulates GnRH drive.

STUDY DESIGN, SIZE, DURATION

This cross-sectional observational study included 15 EW and 12 non-obese women with PCOS who consented to a lumbar puncture in addition to 24 h of serum blood collection at 15-min intervals.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, 27 women were studied at a the General Clinical Research Center (GCRC) at the University of Pittsburgh. Serum analytes included T, E2 and androstenedione. CSF analytes included GABA, glutamate, glucose, T and E2.

MAIN RESULTS AND THE ROLE OF CHANCE

Women with PCOS had higher CSF GABA as compared to EW (9.04 versus 7.04 μmol/L, P < 0.05). CSF glucose and glutamate concentrations were similar between the two groups. CSF T was 52% higher (P = 0.1) and CSF E2 was 30% higher (P < 0.01) in women with PCOS compared to EW. Circulating T was 122% higher (P < 0.01) and circulating E2 was 75% higher (P < 0.01) in women with PCOS than in EW.

LIMITATIONS REASONS FOR CAUTION

The study is limited by its small sample size and the technical limitations of measuring CSF analytes that are pulsatile and have short half-lives.

WIDER IMPLICATIONS OF THE FINDINGS

Women with PCOS displayed significantly higher circulating levels of T and E2, significantly higher CSF levels of E2, and higher levels of CSF testosterone, although the latter was not statistically significant. A better understanding of the central milieu informs our understanding of the mechanisms mediating increased the GnRH drive in PCOS and lends a new perspective for understanding the presentation, pathogenesis and potential health consequences of PCOS, including gender identity issues.

STUDY FUNDING/COMPETING INTEREST(S)

No conflicts of interest. The study was funded by NIH grants to SLB (RO1-MH50748, U54-HD08610) and NIH RR-00056 to the General Clinical Research Center of the University of Pittsburgh.

TRIAL REGISTRATION NUMBER

NCT01674426.

National audit of cerebrospinal fluid testing

Background: UK National External Quality Assessment Service (NEQAS) Specialist Advisory Group for EQA of CSF Proteins and Biochemistry was interested in current practice for the biochemical investigation of cerebrospinal fluid (CSF) in the UK.

Methods: A questionnaire was sent to laboratories via regional audit committees and the results collated.

Results: Most laboratories were analysing CSF in a satisfactory manner. There was some variation in the reference ranges used for glucose, protein and lactate. There was concern about the rejection policies of some laboratories on these unrepeatable samples and the wavelengths used to measure bilirubin. The survey revealed the lack of spectrophotometric scanning for haem pigments and bilirubin in some hospitals.

Conclusions: The current practice for the measurement of CSF samples in the UK is satisfactory in most laboratories responding to the questionnaire. National agreement on reference ranges for glucose, protein and lactate should be achievable. Those performing spectrophotometric scanning of the CSF were doing so in concordance with the national guidelines. Some hospitals in the UK may not have responded to the questionnaire because they did not offer spectrophotometric scanning.

Alcohol in Cerebrospinal Fluid (CSF) and Alcoholism

Alcohol levels were measured in 15 cerebrospinal fluid (CSF) samples and 14 blood samples from grade III and IV male alcoholic patients with signs of nervous system involvement, and compared with levels detected in 11 CSF samples and 11 blood samples from abstemious patients or patients with grade I or II alcoholism whose CSF had been found to be normal by routine analysis (controls). Among the alcoholic patients, alcohol levels were lower in the CSF than in blood, whereas the opposite was true for the controls. The possible mechanisms underlying this difference are discussed and the need for further study of this topic is emphasized.

Method of intracranial pressure monitoring and cerebrospinal fluid sampling in swine

Cerebral oedema and encephalopathy have been noted to occur frequently in patients severely ill or dying after trauma, ischaemia, infections or even metabolic disorders. The objective of the present study was to establish continuous monitoring of the intracranial pressure (ICP) and sampling of cerebrospinal fluid (CSF) for further investigations in swine.

ICP monitoring was established in eight pigs by using a ventricular drainage system, implemented after paramedian trepanation of the os frontale. CSF and serum samples were taken for measurement of the levels of glucose and protein.

Operating time was 21±8 min for the trepanation until ICP monitoring was performed. No complications occurred during surgery. Continuous monitoring of ICP and CSF sampling was easy to perform, and without any side-effects in any animal. At autopsy, no iatrogenic lesions were found and monitoring catheters were still in place.

For several types of research requiring ICP monitoring and sampling of CSF, this method can be used successfully.

The longitudinal cerebrospinal fluid metabolomic profile of amyotrophic lateral sclerosis

Neurochemical biomarkers are urgently sought in ALS. Metabolomic analysis of cerebrospinal fluid (CSF) using proton nuclear magnetic resonance ((1)H-NMR) spectroscopy is a highly sensitive method capable of revealing nervous system cellular pathology. The (1)H-NMR CSF metabolomic signature of ALS was sought in a longitudinal cohort. Six-monthly serial collection was performed in ALS patients across a range of clinical sub-types (n = 41) for up to two years, and in healthy controls at a single time-point (n = 14). A multivariate statistical approach, partial least squares discriminant analysis, was used to determine differences between the NMR spectra from patients and controls. Significantly predictive models were found using those patients with at least one year's interval between recruitment and the second sample. Glucose, lactate, citric acid and, unexpectedly, ethanol were the discriminating metabolites elevated in ALS. It is concluded that (1)H-NMR captured the CSF metabolomic signature associated with derangements in cellular energy utilization connected with ALS, and was most prominent in comparisons using patients with longer disease duration. The specific metabolites identified support the concept of a hypercatabolic state, possibly involving mitochondrial dysfunction specifically. Endogenous ethanol in the CSF may be an unrecognized novel marker of neuronal tissue injury in ALS.

Serum glucose adjusted cut-off values for normal cerebrospinal fluid/serum glucose ratio: implications for clinical practice

BACKGROUND

Calculation of the cerebrospinal fluid/serum glucose (CSF/SGlu) ratio is part of the routine CSF work-up, however, different cut-off values ranging from 0.3 to 0.5 have been suggested so far to distinguish physiological from pathological conditions. The objective of this study was to determine cut-off values for normal CSF/SGlu ratio dependent on serum glucose concentrations.

METHODS

We screened our database for paired CSF and serum samples, which have been collected by lumbar puncture, were processed within 1 h after withdrawal, showed cell count <15/3, erythrocyte count <1500/3 and normal CSF total protein resulting in 1036 sample pairs. Glucose concentrations in CSF and serum were measured by enzymatic spectrophotometry.

RESULTS

Median glucose concentration in CSF was approximately 60% of that in serum. CSF/SGlu ratios negatively correlated with serum glucose levels (R=-0.586, p<0.001) and cut-off values for normal CSF/SGlu ratio defined as the 5th percentile were 0.5 for patients with serum glucose concentrations <100 mg/dL, 0.4 for those with a glucose level of 100-149 mg/dL and 0.3 for serum glucose concentrations ≥150 mg/dL.

CONCLUSIONS

CSF/SGlu ratio inversely correlates with serum glucose concentrations in a non-linear manner. These findings suggest that cut-off values for normal CSF/SGlu ratio must be adjusted to serum glucose levels, probably explaining the considerably varying cut-offs that have been reported so far.

The brain response to peripheral insulin declines with age: a contribution of the blood-brain barrier?

Objectives

It is a matter of debate whether impaired insulin action originates from a defect at the neural level or impaired transport of the hormone into the brain. In this study, we aimed to investigate the effect of aging on insulin concentrations in the periphery and the central nervous system as well as its impact on insulin-dependent brain activity.

Methods

Insulin, glucose and albumin concentrations were determined in 160 paired human serum and cerebrospinal fluid (CSF) samples. Additionally, insulin was applied in young and aged mice by subcutaneous injection or intracerebroventricularly to circumvent the blood-brain barrier. Insulin action and cortical activity were assessed by Western blotting and electrocorticography radiotelemetric measurements.

Results

In humans, CSF glucose and insulin concentrations were tightly correlated with the respective serum/plasma concentrations. The CSF/serum ratio for insulin was reduced in older subjects while the CSF/serum ratio for albumin increased with age like for most other proteins. Western blot analysis in murine whole brain lysates revealed impaired phosphorylation of AKT (P-AKT) in aged mice following peripheral insulin stimulation whereas P-AKT was comparable to levels in young mice after intracerebroventricular insulin application. As readout for insulin action in the brain, insulin-mediated cortical brain activity instantly increased in young mice subcutaneously injected with insulin but was significantly reduced and delayed in aged mice during the treatment period. When insulin was applied intracerebroventricularly into aged animals, brain activity was readily improved.

Conclusions

This study discloses age-dependent changes in insulin CSF/serum ratios in humans. In the elderly, cerebral insulin resistance might be partially attributed to an impaired transport of insulin into the central nervous system.

1H-NMR-based metabolomic analysis of cerebrospinal fluid from adult bilateral moyamoya disease: comparison with unilateral moyamoya disease and atherosclerotic stenosis

Although metabolomics has been increasingly used to observe metabolic pattern and disease-specific metabolic markers, metabolite profiling for moyamoya disease (MMD) has not yet been done in adults. This study investigated cerebrospinal fluid (CSF) metabolites specific to bilateral MMD (B-MMD) and compared them to those of unilateral MMD (U-MMD) or atherosclerotic stenosis with hydrogen-1 nuclear magnetic resonance spectroscopy to identify metabolic biomarkers associated with MMD in adults.CSF samples of B-MMD (n = 29), U-MMD (n = 11), and atherosclerotic cerebrovascular disease (ACVD) (n = 8) were recruited. Principal component analysis, partial least square discriminant analysis, and orthogonal projections to latent structure discriminant analysis (OPLS-DA) were done for the comparisons. Diagnostic performance was acquired by prediction of 1 left-out sample from the distinction model constructed with the rest of the samples.B-MMD showed an increase in glutamine (P < 0.001) and taurine (P = 0.004), and a decrease in glucose (P < 0.001), citrate (P = 0.002), and myo-inositol (P = 0.006) than those in ACVD. U-MMD showed a higher level of glutamine (P = 0.005) and taurine (P = 0.034), and a lower level of glutamate (P < 0.004) than those in ACVD. No difference at the metabolite level was observed between B-MMD and U-MMD. Cross-validation with the OPLS-DA model showed a high accuracy for the prediction of MMD.The results of the study suggest that a metabolomics approach may be helpful in confirming MMD and providing a better understanding of MMD pathogenesis. Elevated glutamine in the CSF may be associated with MMD pathogenesis, which was different from ACVD.

Community-acquired meningitis in older adults: clinical features, etiology, and prognostic factors

OBJECTIVES

To investigate the epidemiology and outcomes of community-acquired meningitis in older adults.

DESIGN

Retrospective study.

SETTING

Participants adults in Houston, Texas, with community-acquired meningitis hospitalized between January 1, 2005, and January 1, 2010 (N = 619; n = 54, 8.7%, aged ≥65; n = 565 aged <65).

METHODS

An adverse clinical outcome was defined as a Glasgow Outcome Scale score of 4 or less.

RESULTS

Older adults had higher rates of comorbidities, abnormal neurological and laboratory (serum white blood cell count >12,000/μL, and cerebrospinal fluid protein >100 mg/dL) findings (P < .001), abnormalities on computed tomography and magnetic resonance imaging of the head (P = .002), and adverse clinical outcomes (ACOs) (P < .001). The majority of participants (65.8%) had meningitis of unknown etiology. Bacterial meningitis was an infrequent cause of community-acquired meningitis (7.4%). Of the known causes, bacterial meningitis and West Nile virus were more common in older than younger adults; younger participants more frequently had cryptococcal and viral meningitis. On logistic regression, female sex was predictive of a poor outcome in the older participants (P = .002), whereas abnormal neurological examination (P < .001), fever (P = .01), and a cerebrospinal fluid glucose level less than 45 mg/dL (P = .002) were significant poor prognostic factors in younger participants.

CONCLUSION

Most cases of community-acquired meningitis are of unknown origin. Older adults are more likely than younger adults to have bacterial meningitis and West Nile virus infection when a cause can be identified. They also have more neurological abnormalities, laboratory and imaging abnormalities, and adverse clinical outcomes.

Scrub typhus meningitis in South India--a retrospective study

Background

Scrub typhus is prevalent in India although definite statistics are not available. There has been only one study on scrub typhus meningitis 20 years ago. Most reports of meningitis/meningoencephalitis in scrub typhus are case reports

Methods

A retrospective study done in Pondicherry to extract cases of scrub typhus admitted to hospital between February 2011 and January 2012. Diagnosis was by a combination of any one of the following in a patient with an acute febrile illness- a positive scrub IgM ELISA, Weil-Felix test, and an eschar. Lumbar puncture was performed in patients with headache, nuchal rigidity, altered sensorium or cranial nerve deficits.

Results

Sixty five cases of scrub typhus were found, and 17 (17/65) had meningitis. There were 33 males and 32 females. Thirteen had an eschar. Median cerebrospinal fluid (CSF) cell count, lymphocyte percentage, CSF protein, CSF glucose/blood glucose, CSF ADA were 54 cells/µL, 98%, 88 mg/dL, 0.622 and 3.5 U/mL respectively. Computed tomography was normal in patients with altered sensorium and cranial nerve deficits. Patients with meningitis had lesser respiratory symptoms and signs and higher urea levels. All patients had received doxycycline except one who additionally received chloramphenicol.

Conclusion

Meningitis in scrub typhus is mild with quick and complete recovery. Clinical features and CSF findings can mimic tuberculous meningitis, except for ADA levels. In the Indian context where both scrub typhus and tuberculosis are endemic, ADA and scrub IgM may be helpful in identifying patients with scrub meningitis and in avoiding prolonged empirical antituberculous therapy in cases of lymphocytic meningitis.

Comparison of clinical and CSF profiles in children with tuberculous and pyogenic meningitis; role of CSF protein: glucose ratio as diagnostic marker of tuberculous meningitis

OBJECTIVES

To compare the clinical and laboratory features of tuberculous meningitis with bacterial meningitis and to determine if protein glucose ratio in the cerebrospinal fluid can be predictive of the condition.

METHODS

It was a retrospective descriptive study at the Paediatric Ward of Aga Khan University Hospital, Karachi, for which records of 46 patients with tuberculous meningitis and 33 with bacterial meningitis were reviewed. All records related to the study period that was from January 2005 to October 2010. The records were retrieved in December 2010. Tuberculous meningitis was defined as illness > or = 14 days, basal enhancement or tuberculoma on computerised tomography scan and response to anti-tuberculous therapy. Pyogenic meningitis was defined by the presence of a pathogenic isolate inthe cerebrospinal fluid (bacterial culture) or by positive latex particle agglutination or a pathogen on cerebrospinal fluid gram stain and clinical improvement with antibiotics. Logistic regression was used to model the probability of having tuberculous meningitis. To define the optimal protein-glucose ratio, cutoff point for the diagnosis of tuberculous meningitis, a receiver operating characteristic curve was applied. All analysis were done using SPSS 16.

RESULTS

Features predictive of a diagnosis of tuberculous meningitis were protein:glucose ratio of > or = 2 (OR 21 95% CI 4.7-93); cerebrospinal fluid total leukocyte count < 800 (OR 58, 95% CI 5-649); and the presence of hydrocephalus (OR 19, 95% CI 3.3-109).

CONCLUSION

A set of simple clinical, laboratory and radiological criteria can help in predicting tuberculous meningitis. The value of cerebrospinal fluid protein:glucose ratio needs to be validated in larger studies with bacteriologically-confirmed cases of tuberculous meningitis.

Meningitis with a negative cerebrospinal fluid Gram stain in adults: risk classification for an adverse clinical outcome

OBJECTIVE

To derive and validate a risk score for an adverse clinical outcome in adults with meningitis and a negative cerebrospinal fluid (CSF) Gram stain.

PATIENTS AND METHODS

We conducted a retrospective study of 567 adults from Houston, Texas, with meningitis evaluated between January 1, 2005, and January 1, 2010. The patients were divided into derivation (N=292) and validation (N=275) cohorts. An adverse clinical outcome was defined as a Glasgow Outcome Scale score of 4 or less.

RESULTS

Of the 567 patients, 62 (11%) had an adverse clinical outcome. A predictive model was created using 3 baseline variables that were independently associated with an adverse clinical outcome (P<.05): age greater than 60 years, abnormal findings on neurologic examination (altered mental status, focal neurologic deficits, or seizures), and CSF glucose level of less than 2.4975 mmol/L (to convert CSF glucose to mmol/L, multiply by 0.05551). The model classified patients into 2 categories of risk for an adverse clinical outcome--derivation sample: low risk, 0.6% and high risk, 32.8%; P<.001; and validation sample: low risk, 0.5% and high risk, 21.1%; P<.001.

CONCLUSION

Adults with meningitis and a negative CSF Gram stain can be accurately stratified for the risk of an adverse clinical outcome using clinical variables available at presentation.

[Evaluation of decreased glucose levels in the cerebrospinal fluid of dogs]

OBJECTIVE

The aim of the study was to evaluate the glucose ratio (glucose level in the cerebrospinal fluid [CSF]/blood glucose level) as a quickly available marker for detecting bacterial meningoencephalomyelitis (BM).

MATERIAL AND METHODS

Blood and CSF samples of 328 dogs were reviewed and evaluated retrospectively. Following the neurological diagnosis, the dogs were assigned to seven different groups: steroid-responsive meningitis-arteritis (SRMA), intervertebral disc disease (IVDD), neoplasia of the central nervous system (N), idiopathic epilepsy (IE), bacterial meningoencephalomyelitis (BM), meningoencephalomyelitis of other origin (ME) and healthy dogs.

RESULTS

The median of the CSF-glucose level (mmol/l) and the median of the glucose ratio in the SRMA group displayed the lowest values and differed significantly from the CSF-glucose levels of dogs in the groups IVDD, N, IE and healthy dogs (CSF-glucose level: p<0.01; glucose ratio: p<0.05). In the BM group, both parameters did not differ significant- ly from other groups, but displayed similar low levels as in the SRMA group. There was a negative correlation between the CSF cell count and the CSF-glucose ratio (Spearman correlation coefficient -0.322, p=0.01, R²=0.108).

CONCLUSION

The CSF-glucose concentration cannot be used as a distinct marker to differentiate BM from other inflammatory CNS-diseases, especially from SRMA usually accompanied by severe pleocytosis. Low CSF-glucose levels appear to be caused by elevated CSF cell counts rather than by bacterial metabolism.

CLINICAL RELEVANCE

For a definitive diagnosis of bacterial meningoencephalomyelitis in dogs, the detection of microorganisms remains necessary.

[The finding of glucose in the fluid obtained by epidural catheter after its insertion during combined intradural-epidural anaesthesia with hyperbaric bupivacaine is a usual occurrence]

OBJECTIVES

To determine whether the appearance of glucose in the fluid spontaneously obtained by the epidural catheter after its insertion during combined intradural-epidural anaesthesia with hyperbaric bupivacaine is a usual occurrence.

PATIENTS AND METHODS

A prospective, observational study was conducted on 34 patients with combined intradural-epidural anaesthesia in whom an epidural catheter was introduced, after locating the epidural space with a saline solution, inserting a spinal needle and injecting hyperbaric bupivacaine. After observing whether any fluid was spontaneously dripping from it, it was determined if this contained glucose. Withdrawal of the needle and washing its lumen with saline solution, it was checked whether there was glucose in washout. The samples were analysed using a glucose meter. When the motor block disappeared a dose of local anaesthetic was administered through the epidural catheter. The relationship of the demographic parameters with the spontaneous dripping of the epidural catheter was evaluated.

RESULTS

Spontaneous dripping by the epidural catheter after its insertion was observed in 22 patients. All the samples obtained contained glucose. There was glucose in 9 out of 34 epidural needle wash samples. None of the patients suffered from excessive motor-sensory block. There was a statistically significant relationship between patient age (P<.05) and spontaneous dripping by the catheter (the higher the age, more dripping).

CONCLUSION

The finding of glucose in the fluid obtained by the epidural catheter is a frequent occurrence and is of no clinical significance. We propose that it could be due to a leak of cerebrospinal fluid by the dural puncture needle during or after the administering of the hyperbaric bupivacaine and the spillage of this into the epidural space.

First report of GLUT1 deficiency syndrome in Chinese patients with novel and hot spot mutations in SLC2A1 gene

Glucose transporter type 1 deficiency syndrome (GLUT1DS) is increasingly recognized as a cause of various neurological disorders but a high index of suspicion is important to make the diagnosis. We report two Chinese patients with GLUT1DS, one of which had a novel mutation in the SLC2A1 gene.

Group B streptococcal meningitis: cerebrospinal fluid parameters in the era of intrapartum antibiotic prophylaxis

OBJECTIVE

Describe cerebrospinal fluid parameters in infants with culture-proven Group B streptococcal meningitis in the era of intrapartum antibiotic prophylaxis.

STUDY DESIGN

Cohort study of the first lumbar puncture from 13,495 infants cared for at 150 neonatal intensive care units. We compared cerebrospinal fluid parameters [white blood cell count, red blood cell count, glucose, and protein], demographics, and outcomes between infants with and without Group B streptococcal meningitis.

RESULTS

We identified 46 infants with Group B streptococcal meningitis. The median cerebrospinal fluid white blood cell count was 271 cells/mm(3) for infants with Group B streptococcal meningitis and 6 cells/mm(3) for infants without meningitis (p=0.0001). Of the infants with Group B streptococcal meningitis, 9/46 (20%) had negative blood cultures. Meningitis complicated 22/145 (15%) of episodes of early-onset Group B streptococcal sepsis and 13/23 (57%) of episodes of late-onset Group B streptococcal sepsis.

CONCLUSIONS

Group B streptococcal meningitis occurs in the presence of negative blood cultures. In hospitalized infants who undergo a lumbar puncture, Group B streptococcal sepsis is frequently complicated by GBS meningitis.

AGT-181: expression in CHO cells and pharmacokinetics, safety, and plasma iduronidase enzyme activity in Rhesus monkeys

Enzyme replacement therapy is not effective for the brain, owing to the lack of transport of the enzyme across the blood-brain barrier (BBB). Recombinant proteins such as the lysosomal enzyme, iduronidase, can penetrate the human BBB, following the re-engineering of the protein as an IgG fusion protein, where the IgG moiety targets an endogenous BBB transport system. The IgG acts as a molecular Trojan horse to ferry the fused protein into brain. AGT-181 is a genetically engineered fusion protein of human iduronidase and a chimeric monoclonal antibody against the human insulin receptor. Adult Rhesus monkeys were administered repeat intravenous doses of AGT-181 ranging from 0.2 to 20 mg/kg. Chronic AGT-181 dosing resulted in no toxicity at any dose, no changes in organ histology, no change in plasma or cerebrospinal fluid glucose, and no significant immune response. AGT-181 was rapidly removed from plasma, based on measurements of either plasma immunoreactive AGT-181 or plasma iduronidase enzyme activity. Plasma pharmacokinetics analysis showed a high systemic volume of distribution, and a clearance rate comparable to a small molecule. The safety pharmacology studies provide the basis for future drug development of AGT-181 as a new therapeutic approach to treatment of the brain in Hurler's syndrome.

The diagnostic accuracy of CSF analyses in stroke

The ability of routine analyses of cerebrospinal fluid (CSF) to differentiate between haemorrhage and infarction was evaluated in 231 stroke patients, whose diagnoses were based on computed tomography or autopsy. In all diagnostic groups the mean protein level was above normal, the highest values being associated with haemorrhage. Taking a protein level greater than 1 g/l to be characteristic of bleeding, sensitivity was 89% and specificity 92%. Spectrophotometric CSF absorbance was measured at wave lengths of 410, 415, 455 and 630 nm. Validity was equal for the first three. Taking absorbance greater than or equal to 0.040 at 415 nm to be diagnostic for haemorrhage, sensitivity was 72% and specificity 94%. The human eye was almost as sensitive as spectrophotometry in this context. Thus, among 100 patients with stroke, 7-9 out of 10 plausible cases of haemorrhage would be identified by means of routine CSF analyses. At the same time, 5-9 patients with ischaemic lesions would be diagnosed incorrectly as bleedings.

[Quantitative test to distinguish spinal fluid from saline solution in combined spinal-epidural anesthesia]

OBJECTIVES

To validate the use of a digital blood glucose meter for detecting the presence of spinal fluid during combined spinal-epidural anesthesia in terms of specificity, positive and negative predictive values, and likelihood ratios.

PATIENTS AND METHODS

Validation was studied in 30 patients scheduled for surgery under combined spinal-epidural anesthesia. A positive finding, defined as detection of spinal fluid return or aspiration by the epidural or spinal needle, was compared with results of standard reference tests (the pattern of sensory or motor block after administration of the local anesthetic). After locating the epidural space with saline solution, the test was performed and 3 mL of local anesthetic was administered. If no sensory or motor blockade was evident, the test was considered a true negative. Spinal puncture was then performed, the test was repeated, and 2 to 3 mL of local anesthetic was injected. The test was considered a true positive if sensory or motor blockade was evident. These findings entered into the validation analyses.

RESULTS

Sensitivity was 100%, specificity 94%, positive predictive value 93%, negative predictive value 100%, the positive likelihood ratio 15.5, and negative likelihood 0.

CONCLUSION

Blood glucose meter readings provide a valid quantitative measure for distinguishing spinal fluid from saline solution during combined spinal-epidural anesthesia. The method, which uses a readily available device, is easy to use to rule out the presence of spinal fluid.

Retrospective study of patients with herpes simplex encephalitis and positive CSF PCR

OBJECTIVE

To determine the clinical presentations, laboratory and imaging findings of patients with HSE and positive CSF PCR then compare these with information from other viral encephalitis patients in order to find clinical clues that might help clinicians in early diagnosis and treatment of HSE while awaiting for the CSF PCR result.

MATERIAL AND METHOD

A patient group with both HSE and positive CSF PCR and a control group of patients with other viral encephalitis were identified from Siriraj Hospital database within the period of 1997-2006. Medical notes of these patients were reviewed and relevant information, including clinical, laboratory and imaging study, were extracted. Then, descriptive statistics, unpaired t-test and Fisher's exact test were performed with the purpose to determine any clinical or laboratory clues that are significantly different between these two groups, which might help clinicians in making an early diagnosis of HSE.

RESULTS

Seven HSE cases and 22 cases in control group were included. Fever, headache, alteration of consciousness, behavioral change, neck stiffness are the most commonly found clinical presentations in HSE patients with CSF PCR positive. CSF examination show CSF leukocytosis with lymphocyte predominate, decreased CSF:blood glucose ratio and elevated CSF protein in all cases. However, no single clinical or laboratory finding helps in differentiating HSE with positive CSF PCR from other viral encephalitides, except radiological abnormalities of temporal lobe, which yields a positive predictive value of 0.5 and a negative predictive value of 0.93.

CONCLUSION

Our study showed that HSE shares common clinical and laboratory findings with other viral encephalitides, except for temporal lobe involvement. Early diagnosis is important and empirical acyclovir should be commenced early in patients with viral encephalitis, especially for those with radiological abnormalities on the temporal lobe.

Tuberculous meningitis in HIV-infected and non-infected patients: comparison of cerebrospinal fluid findings

We performed a retrospective comparison of cerebrospinal fluid (CSF) characteristics and drug susceptibility profile in human immunodeficiency virus (HIV) infected and non-infected patients with a diagnosis of tuberculous meningitis. HIV-infected patients had a higher frequency of non-inflammatory CSF (absence of pleocytosis) and of infection by multidrug-resistant strains of Mycobacterium tuberculosis. Protein CSF levels were lower in HIV-infected patients, while and glucose concentration was similar in both groups. Hospital mortality was significantly higher in HIV-infected patients (63.3% [64/101] vs. 17.5% [7/40]).

Identifying low-risk patients for bacterial meningitis in adult patients with acute meningitis

OBJECTIVE

To derive and validate a clinical prediction model with high sensitivity for differentiating aseptic meningitis (AM) patients from bacterial meningitis (BM) patients.

METHODS

We developed the model using the derivation cohort in a community rural hospital in Okinawa and assessed its performance using the validation cohort in a metropolitan urban hospital in Tokyo. There were 66 (39.5%) and 5 (17.9%) adult patients with BM among the derivation (n=167) and the validation cohort (n=28), respectively. Recursive partitioning analysis was used to determine the important classification variables and to develop a sensitive model to safely exclude BM.

RESULTS

The model produced high- and low-risk groups based on the following: 1) Gram stain, 2) CSF neutrophil percent < or =15%, 3) CSF neutrophil count < or =150 cells/mm(3), and, 4) mental status change. Among the derivation cohort, there were 65 patients with BM in the high-risk group (n=76), while only one patient with BM was noted (sensitivity, 99%) in the low-risk group (n=91). Among the validation cohort, there were 5 patients with BM in the high-risk group (n=7), while no patient was classified with BM (sensitivity, 100%) in the low-risk group (n=21).

CONCLUSION

This simple and sensitive model might be useful to safely identify low-risk patients for BM who would not require antibiotic treatment.