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Recent findings indicate that nitric oxide (NO*) over-production might be an important factor in the pathogenesis of sporadic amyotrophic lateral sclerosis (SALS). We measured significantly higher concentrations of uric acid and thiol group-containing molecules (R-SH groups) in the cerebrospinal fluid (CSF) from SALS patients compared to controls. The above factors, together with a slightly increased free iron concentration found in the CSF, favour conditions necessary for the formation of the dinitrosyl iron complex, capable of NO* bio-transformation. Thus, we performed ex vivo saturation of CSF (from both SALS patients and controls) with NO*. A decrease in the level of R-SH was found. This was more pronounced in the CSF from SALS patients. In the CSF from SALS patients the production of nitrite and hydroxylamine was greater than that observed in the CSF from controls. Moreover, we also found increased Cu,Zn-SOD activity in the CSF from SALS patients (when compared to control subjects) but no activity corresponding to Mn-SOD in any CSF samples. As Cu,Zn-SOD can react with nitroxyl forming NO*, the conditions for a closed, but continuous, loop of NO* biotransformation are present in the CSF of ALS patients.

Background: Japanese encephalitis virus (JEV), the mosquito-borne flavivirus, annually causes an estimated 35,000-50,000 encephalitis cases and 10,000-15,000 deaths in Asia, and there is no antiviral treatment. The role played by the immune response in determining the outcome of human infection with JEV is poorly understood, although, in animal models of flavivirus encephalitis, unregulated proinflammatory cytokine responses can be detrimental., Methods: We studied the innate, cellular, and humoral immune responses in 118 patients infected with JEV, of whom 13 (11%) died., Results: Levels of interferon (IFN)- alpha , the proinflammatory cytokine interleukin (IL)-6, and the chemokine IL-8 were all higher in the cerebrospinal fluid (CSF) of the nonsurvivors than of the survivors (P=.04, P=.006, and P=.04, respectively), as were both the IL-6 : IL-4 ratio in CSF (a marker of the balance of pro- and anti-inflammatory cytokines) and the level of the chemokine RANTES (regulated on activation, normally T cell expressed and secreted) in plasma (P=.03). In contrast, levels of immunoglobulin (Ig) M and IgG in CSF and of IgM in plasma were higher in the survivors (P=.035, P=.003, and P=.009, respectively). Levels of IFN- gamma and nitric oxide did not vary with outcome., Conclusions: During JEV infection, elevated levels of proinflammatory cytokines and chemokines are associated with a poor outcome, but whether they are simply a correlate of severe disease or contribute to pathogenesis remains to be determined.

Object: Decreased availability of nitric oxide (NO) has been proposed to evoke delayed cerebral vasospasm after sub-arachnoid hemorrhage (SAH). Asymmetric dimethyl-L-arginine (ADMA) inhibits endothelial NO synthase (eNOS) and, therefore, may be responsible for decreased NO availability in cases of cerebral vasospasm. The goal of this study was to determine whether ADMA levels are associated with cerebral vasospasm in a primate model of SAH., Methods: Twenty-two cynomolgus monkeys (six control animals and 16 with SAH) were used in this study. The levels of ADMA, L-arginine, L-citrulline, nitrites, and nitrates in cerebrospinal fluid (CSF) and serum were determined on Days 0, 7, 14, and 21 following onset of SAH. Cerebral arteriography was performed to assess the degree of vasospasm. Western blot analyses of the right and left middle cerebral arteries (MCAs) were performed to assess the expression of eNOS, type I protein-arginine methyl transferase (PRMT1) and dimethylarginine dimethylaminohydrolase (DDAH2). Cerebrospinal fluid levels of ADMA remained unchanged in the control group (six animals) and in animals with SAH that did not have vasospasm (five animals; p = 0.17), but the levels increased in animals with vasospasm (11 animals) on Day 7 post-SAH (p < 0.01) and decreased on Days 14 through 21 (p < 0.05). Cerebrospinal fluid levels of ADMA correlated directly with the degree of vasospasm (correlation coefficient = 0.7, p = 0.0001; 95% confidence interval: 0.43-0.83). Levels of nitrite and nitrate as well as those of L-citrulline in CSF were decreased in animals with vasospasm. Furthermore, DDAH2 expression was attenuated in the right spastic MCA on Day 7 post-SAH, whereas eNOS and PRMT1 expression remained unchanged., Conclusions: Changes in the CSF levels of ADMA are associated with the development and resolution of vasospasm found on arteriograms after SAH. The results indicate that endogenous inhibition of eNOS by ADMA may be involved in the development of delayed cerebral vasospasm. Inhibition of ADMA production may provide a new therapeutic approach for cerebral vasospasm after SAH.

Oxidative stress leads to lipid peroxidation and may contribute to the pathogenesis of lesions in multiple sclerosis (MS), an autoimmune disease characterised by inflammatory as well as degenerative phenomena. We previously found that cerebrospinal fluid (CSF) levels of isoprostane 8-epi-PGF2alpha, a marker of free radical damage and lipid peroxidation in vivo, were elevated in MS patients. Such levels were correlated with the degree of disability and reduced in subjects under steroid therapy. Here we investigated weather the CSF isoprostane levels correlated with disease inflammatory activity. To this aim, we enrolled 41 relapsing-remitting (RR) MS patients who underwent at the same time full neurological examination, NMR-imaging brain scan and diagnostic CSF test. No evidence of correlation was found between 8-epi-PGF2alpha levels and the presence of gadolinium (Gd)-enhancing NMR lesions or the time elapsed since the last relapse. We suggest that isoprostanes are not useful as surrogate inflammatory markers in MS. However, they may represent a sensitive index of degenerative phenomena, which can persist also in the absence of inflammatory activity.

Excitatory amino acids, cytokines and nitric oxide (NO) have been studied in the etiology and pathogenesis of hypoxic ischemic encephalopathy (HIE) of the newborn. Vascular endothelial growth factor (VEGF) is a known mediator of angiogenesis and has been shown to induce vascular proliferation and permeability via NO-mediated mechanism during hypoxia. The objective of this study was to investigate the cerebrospinal fluid and serum VEGF and NO levels in different stages of HIE and the correlation between the two mediators. Cerebrospinal fluid (CSF) and serum samples of 19 newborns with HIE and 13 controls were obtained within the first 24 h of life and kept at -70 degrees C until the time of measurement. NO levels were determined by Sievers NOA by chemiluminescence method and VEGF levels were measured by the enzyme-linked immunosorbent assay double sandwich method. The NO levels in CSF were higher than the control and mild HIE group in newborns with moderate to severe HIE, and VEGF levels in CSF were higher in the mild HIE group compared to controls but similar in the moderate to severe HIE group compared to mild HIE and control patients. There was no difference between groups with regard to serum NO or VEGF levels, and no correlation was observed between NO and VEGF levels both in CSF and serum samples. Depending on the severity of the hypoxic insult the stimulus for NO production by VEGF may have variable effects on endothelial cells which may give rise to the current results.

The effect of the pro-inflammatory cytokine interleukin-1beta (IL-1beta) on the inducible nitric oxide synthase-nitric oxide (iNOS-NO) cascade in nociceptive signal transduction was examined in the intact rat spinal cord. All rats were implanted with an intrathecal (i.t.) catheter; some were also implanted with an i.t. microdialysis probe. The paw withdrawal latency to radiant heat was used to assess thermal hyperalgesia. The iNOS protein expression in the spinal cord dorsal horn was examined by western blot analysis and NOS activity assay. NO production in the CSF dialysate was also measured. IL-1beta i.t. (100 ng) produced thermal hyperalgesia from 4 to 24 h after i.t. injection. The iNOS protein expression was induced at 4 h after i.t. IL-1beta injection, peaked at the 6th hour, and disappeared at 24 h. The iNOS activity showed a similar time-dependent change as the iNOS protein expression. NO release increased by 1.1- to 1.9-fold between 4 and 12 h, also with a peak at the 6th hour, after i.t. IL-1beta administration. Pretreatment with the iNOS inhibitor 1400W (10 microg, i.t.) 1 h before i.t. IL-1beta injection prevented all the responses of IL-1beta. Neither 1400W nor artificial CSF (aCSF) affected the thermal nociceptive threshold and NO production. These results demonstrate that i.t. administration of IL-1beta induced thermal hyperalgesia by activating the iNOS-NO cascade in the rat spinal cord. On the basis of the present findings, we suggest that i.t. administration of iNOS inhibitors may have potential in the treatment of inflammatory and neuropathic pain syndromes.

The potential value of the nitric oxide (NO) level as a prognostic marker in human brain diseases is investigated. Cerebrospinal fluid (CSF) collected from neurological patients was examined for NO content using electron paramagnetic resonance (EPR) spectroscopy. In adult patients with meningitis, the level of NO was higher than that in other groups of brain disorders, such as brain traumas and brain tumors. Very high levels of NO in the CSF appeared to be correlated with a high incidence of fatal outcomes. In children with meningitis, it was possible to differentiate between viral and bacterial origin of the disease as evidenced by the EPR analysis of the CSF. The results indicated that NO levels in the CSF can be a useful prognostic marker in neurological diseases.

Objectives: Many studies have shown that nitric oxide (NO) and growth factors including insulin growth factors (IGFs) may be involved in the pathogenesis of multiple sclerosis (MS) and neurodegenerative diseases. Our previous studies suggested a relationship between cerebrospinal fluid (CSF) NO metabolites (nitrates and nitrites, NN(x)) and IGF-1 in patients with progressive encephalopathy, hypsarrhythmia and optic atrophy syndrome., Material and Methods: We examined CSF concentrations of NN(x), IGF-1 and IGF binding protein-2 (IGFBP-2) in 25 controls, 14 patients with MS and 14 patients with amyotrophic lateralis sclerosis (ALS)., Results: There were no significant differences in CSF levels of NN(x), IGF-1 or IGFBP-2 between the groups. CSF IGFBP-2 concentrations correlated significantly with age in controls, which may reflect age-related changes in the blood-brain barrier function., Conclusion: Upregulation of the production of NO and IGF-1 in the brain or spinal cord does not influence CSF levels of these molecules in MS or ALS.

Objective: The purpose of this study was to determine the level of nitric oxide (NO) metabolites, nitrite and nitrate in human cerebrospinal fluid (CSF) and serum and to assess whether there is any relationship among CSF, serum nitrate-nitrite levels and preeclampsia., Study Design: Twenty-one preeclamptic and 27 healthy pregnant women as control group who underwent cesarean section (C/S) were included in the study. Before administering local anesthetic for spinal anesthesia, 2 ml CSF and 4 ml venous blood sample were taken. CSF and serum total nitrite, direct nitrite and nitrate levels were determined spectrophotometrically., Results: CSF total nitrite, direct nitrite and nitrate levels were significantly different between the two groups (21.00+/-1.68, 8.28+/-0.89 and 12.71+/-1.08 micromol/l, respectively versus 15.53+/-1.49, 5.57+/-0.39 and 9.96+/-1.45 micromol/l, respectively, P<0.05). Significantly higher serum nitrate level was found (31.84+/-2.31 micromol/l) in the control group compared to the preeclamptic group serum nitrate level (25.06+/-2.02 micromol/l). Statistical comparisons were performed by the Mann-Whitney U-test., Conclusion: CSF-NO is significantly higher but serum NO is lower in preeclamptic group compared with control group may suggest independent regulation of NO in the two compartments. The determination of CSF-NO metabolites could be useful to clarify whether increased NO production is predominantly associated with poor perfusion of the brain in preeclampsia.

Objectives: One of the fundamental aspects of nitric oxide (NO) is the regulation of the inflammatory processes involved in neuronal apoptosis. Expressions of NO and NO synthase (NOS) are considered to be involved in brain tissue injuries and brain tumors. The purpose of our study was to investigate the roles of NO and inducible-form NOS (iNOS) in the pathogenesis of brain tumors., Methods: NO levels in the cerebrospinal fluid (CSF) of 36 brain tumor patients were detected utilizing the NO-chemiluminescence method. Deparaffinized tissue sections were immunostained for the presence of antibodies against iNOS and for apoptosis using the TUNEL stain. The results were compared with 10 control patients (with epilepsy and hydrocephalus)., Conclusions: Higher levels of NO and iNOS activities may induce immune responses and neurotoxicities. This preliminary study revealed elevated NO and NOS activities with an increased amount of apoptotic processes in brain tumor tissues, which may indicate the possible roles of NO in the formation of brain tumors.

It has become evident that the number of patients with a new type of influenza-associated encephalopathy is increasing in Japan. Nitric oxide (NO), a simple free radical gas, elicits a wide range of physiological and pathophysiological effects. We measured the nitrite/nitrate (NO x ) levels in cerebral spinal fluid obtained from patients with influenza-associated encephalopathy in order to evaluate the correlation between the NO production and the process of influenza-associated encephalopathy. Fifteen children were enrolled, aged from 1 to 9 years. As control we used 14 cerebral spinal fluids obtained from patients with urinary tract infection, respiratory infection or mumps meningitis without any sequela. NO 3 in influenza-associated encephalopathy was significantly higher than that of control group. On the other hand NO 2 was not significantly higher than that of control group. In particular, 4 out of 5 fatal cases revealed high NO 2 or NO 3. One case having normal levels in NO 2 and NO 3 showed that NH 3 was high. These results revealed that NO plays a role in influenza-associated encephalopathy through indirect effects of NO.

To determine whether or not the occurrence of sporadic amyotrophic lateral sclerosis (sALS) is associated with both excess nitric oxide (NO) metabolites and decreased protective superoxide dismutase (SOD) activity in the cerebrospinal fluid (CSF), we measured nitrate concentration and SOD activity in the CSF of sALS patients and in age- and gender-matched controls. We found stable NO metabolite levels to be significantly higher and SOD activity lower in the CSF of sALS patients. In addition, SOD showed a negative correlation with motor neuron axonal damage expressed as the amplitude of motor action potentials in upper limbs. Our results provide new evidence in vivo suggesting that NO products and SOD activity play a role in oxidant/ antioxidant imbalance in sporadic ALS.

Nitric oxide (NO) molecules have one of the most important roles in the pathogenesis of multiple sclerosis (MS). It has been stated that a continuous and high concentration of NO metabolites in CSF and in the serum of MS patients in relapse may cause toxic damage to myelin and oligodendroglia. The aim of this study was to investigate whether NO is a marker of disease activity and is correlated with other disease activity markers such as active lesions on brain magnetic resonance imaging (MRI) and increased immunoglobulin G (IgG) index. Cerebrospinal fluid (CSF) and peripheral serum (PS) samples were taken from patients with definite MS (n = 24) during relapse and remission and from control subjects (n = 18). The Griess reaction was used to measure the NO metabolites, nitrite and nitrate in CSF and PS. Cranial MRI was carried out with triple dose (0,3 mmol/kg) gadolinium and the IgG index was determined. Nitrite and nitrate concentrations (NNCs) of CSF were 11.16 +/- 8.60 micromol/ml in relapse and 6.72 +/- 3.50 micromol/ml in remission, whereas in PS they were 12.89 +/- 7.62 micromol/ml during relapse and 12.35 +/- 6.62 micromol/ml during remission. In control subjects NNCs in CSF and PS were 7.42 +/- 2.81 micromol/ml and 4.37 +/- 1.63 micromol/ml respectively. NNCs in CSF during relapse period were significantly higher than those of both remission phase and control subjects (p = 0.000). Although serum NNCs did not differ in relapse and remission, they were still higher than normal controls. Validity analysis revealed that NNC measurement in CSF was 71 % specific and 66 % sensitive to disease activity. The most important result was the significant correlation of increased NNCs with the existence of active lesion in cranial MRI and an increase in IgG index (p < 0.05).In conclusion, these results add background data to assist in further outlining the possible role of NO in the pathogenesis of MS. Together with the other markers it may be used as an activity marker in relapses of MS.

A central sensitization has been advocated to explain chronic daily headache (CDH) due to sustained peripheral sensitization of allogenic structures responsible for sustained trigeminovascular system activation. Several mechanisms have been suggested to underlie central sensitization, but have been poorly investigated in CDH. They involve N-methyl-D-aspartate (NMDA) receptor activation and nitric oxide (NO) production and supersensitivity and increased and maintained production of sensory neuropeptides. The present study supports the above pathogenic mechanisms demonstrating a significant increase in glutamate and nitrite levels in the CSF of CDH patients, without a significant difference between patients without and those with analgesic overuse headache (P < 0.0001 and P < 0.002). The increase in CSF nitrites was accompanied by a significant rise in the CSF values of cyclic guanosine monophosphate (cGMP) in patients in comparison with controls (P < 0.0001). A statistically significant correlation emerged between visual analogic scale (VAS) values and glutamate, nitrites and cGMP. Although substance P (SP) and calcitonin gene-related peptide (CGRP), and to a lesser extent neurokinin A, were significantly increased in CSF compared with control subjects, their values did not correlate with glutamate, nitrites and cGMP levels in CSF in the patient group. The present study confirms the involvement of glutamate-NO-cGMP-mediated events underlying chronic head pain that could be the target of a new therapeutic approach which should be investigated.

We measured neopterin, biopterin and nitric oxide (NO) concentrations in the cerebrospinal fluid of pediatric patients with central nervous system (CNS) infectious diseases. The nitric oxide and neopterin concentrations were significantly elevated in encephalitis patients, especially in two cases with serious neurological sequelae, while the biopterin levels were not elevated. The bacterial meningitis patients, on the contrary, had high cerebrospinal fluid concentrations of neopterin and biopterin, but not of NO. Although these findings are preliminary, it may suggest that cerebrospinal fluids nitric oxide would be a useful marker to prospect neurological prognoses in the CNS infections.

Nitric oxide (NO) and prostaglandins are inflammatory mediators produced during meningitis. The purpose of the present study was to pharmacologically inhibit cyclooxygenase-2 (COX-2) and inducible NO synthase (iNOS) to 1) explore the prostaglandin contribution to blood-cerebrospinal fluid barrier permeability alterations and 2) elucidate the in vivo concentration relationship between prostaglandin E2 (PGE2) and NO during experimental meningitis. Intracisternal injection of lipopolysaccharides (LPSs, 200 microg) induced neuroinflammation. Rats were dosed with nimesulide (COX-2 inhibitor), aminoguanidine (iNOS inhibitor), or vehicle. Evans blue was used to assess blood-cerebrospinal fluid barrier permeability. Meningeal NO and cerebrospinal fluid PGE2 were assayed using conventional methods. (Results are expressed as mean +/- S.E.M. of 5-9 rats/group.) Nimesulide failed to prevent blood-cerebrospinal fluid barrier disruption [cerebrospinal fluid Evans blue (micrograms per milliliter): control, 0.22 +/- 0.22*; LPS, 11.58 +/- 0.66; LPS + nimesulide, 10.58 +/- 0.86; *p < 0.05; ANOVA]. Although nimesulide decreased PGE2 (picograms per microliter; p < 0.01) in LPS + nimesulide rats (13.9 +/- 1.96) versus LPS + vehicle (73.8 +/- 12.4), meningeal NO production (picomoles/30 min/10(6) cells; p < 0.01) increased unexpectedly in LPS + nimesulide rats (439 +/- 47) versus LPS + vehicle rats (211 +/- 31). In contrast, aminoguanidine inhibited meningeal NO (picomoles/30 min/10(6) cells; p < 0.005) in LPS + aminoguanidine (111 +/- 20) versus LPS (337 +/- 48) but had no effects (p > 0.05) on PGE2. The in vivo relationship between PGE2 and NO was mathematically described by a biphasic, bell-shaped curve (r2 = 0.42; n = 27 rats; p < 0.0001). Based on these results, inhibition of prostaglandin synthesis not only fails to prevent blood-cerebrospinal fluid barrier disruption during neuroinflammation and but also promotes increased meningeal NO production. The in vivo concentration relationship between PGE2 and NO is biphasic, suggesting that inhibition of COX-2 alone may promote NO toxicity through enhanced NO synthesis.

The objective of this study was to determine the role of cerebral nitric oxide and its powerful oxidant peroxynitrite following mild birth asphyxia. The cerebrospinal fluid levels of nitric oxide and 3-nitrotyrosine as a marker for peroxynitrite are measured in neonates with mild hypoxic-ischemic encephalopathy. Based on the classification of Sarnat and Sarnat, term neonates with mild hypoxic-ischemic encephalopathy and neurologically normal neonates suspected of sepsis were taken as the control group. Nitric oxide measurements were done by chemiluminescence, and nitrotyrosine measurements were made by high-performance liquid chromatography. The Mann Whitney U-test was used, and a Pvalue < .05 was considered significant. Eleven patients with grade 1 hypoxic-ischemic encephalopathy and nine controls were included. The gestational age and birthweights were similar in both groups. Neither of the cerebrospinal fluid levels of nitric oxide (8.60 +/- 0.49 micromol/L) and nitrotyrosine (0.45 +/- 0.33 micromol/L) of the neonates with hypoxic-ischemic encephalopathy showed significant differences from that of the means of nitric oxide (8.66 +/- 1.07 micromol/L) and nitrotyrosine levels (0.25 +/- 0.13 micromol/L) of the controls. These data suggest that the oxidative stress is not overexpressed to lead nitric oxide and peroxynitrite to play a pathologic role in the early phase of mild hypoxic-ischemic encephalopathy of the newborn.

The mechanism responsible for the reduced clearance of benzylpenicillin (BPC) from the cerebrospinal fluid (CSF) was investigated in rats that received an intracisternal administration of lipopolysaccharide (LPS). BPC was intraventricularly injected and its elimination from the CSF studied. During the inflammation created by the LPS administration to the cisterna magna, the clearance of BPC and taurine from the CSF was significantly reduced but reverted to the control level when N-nitro-L-arginine, a nitric oxide (NO) synthase inhibitor, was intracisternally administered. The in vitro uptake of BPC and taurine was significantly reduced in the choroid plexus (CP, the blood-CSF barrier) of rats with experimental inflammation and in control CP that had been pretreated with sodium nitroprusside (SNP, an NO donor). Interestingly, the clearance and CP uptake of formycin B, a substrate for a nucleoside transporter, were not affected by the experimental inflammation or by pretreatement with SNP. These observations suggest that the BPC transporter, and probably other transport systems as well, is functionally sensitive to NO in the blood-CSF barrier. Therefore, functional impairment of BPC transport in the CP by NO may be partly responsible for the increase in BPC concentration in the CSF during inflammation such as that caused by meningitis.

Interleukin-6 (IL-6) and nitric oxide (NO) are implicated in the pathology of multiple sclerosis (MS). We have investigated the levels of these mediators in the cerebrospinal fluid (CSF) from 50 patients with MS and 23 control subjects. Mean CSF IL-6 level was higher in the total MS group in comparison with controls, but not significantly, whilst the difference between patients with stable MS and controls reached the level of statistical significance. Mean CSF nitrite/nitrate level was significantly higher in the total MS group compared with the control group, as well as in active MS patients versus controls. There was significant difference neither in the mean CSF IL-6 nor in nitrite/nitrate levels between active and stable MS patients. Interestingly, we observed a significant negative correlation between IL-6 and nitrite/nitrate levels in the CSF in the total MS group. Such a trend existed in both subgroups with active and stable MS, but without reaching the level of statistical significance. Our data further support the involvement of IL-6 and NO in ongoing pathological processes in MS, suggesting their potential interplay within the central nervous system in this disease.

Equine protozoal myeloencephalitis (EPM) is a disease of horses that is primarily associated with infection with the apicomplexan Sarcocystis neurona. Infection with this parasite alone is not sufficient to induce the disease, and the mechanism of neuropathogenesis associated with EPM has not been reported. Nitric oxide (NO) functions as a neurotransmitter, a vasodilator, and an immune effector and is produced in response to several parasitic protozoa. The purpose of this work was to determine if the concentration of NO metabolites (NO(x)(-)) in the cerebrospinal fluid (CSF) is correlated with the development of EPM. CSF NO(x)(-) levels were measured before and after transport-stressed, acclimated, or dexamethasone-treated horses (n = 3 per group) were experimentally infected with S. neurona sporocysts. CSF NO(x)(-) levels were also compared between horses that were diagnosed with EPM after natural infection with S. neurona and horses that did not have clinical signs of disease or that showed no evidence of infection with the parasite (n = 105). Among the experimentally infected animals, the mean CSF NO(x)(-) levels of the transport-stressed group, which had the most severe clinical signs, was reduced after infection, while these values were found to increase after infection in the remaining groups that had less severe signs of EPM. Under natural conditions, horses with EPM (n = 65) had a lower mean CSF NO(x)(-) concentration than clinically normal horses with antibodies (Abs) against S. neurona (n = 15) in CSF, and horses that developed ataxia (n = 81) had a significantly lower mean CSF NO(x)(-) concentration than horses that did not have neurologic signs (n = 24). In conclusion, lower CSF NO(x)(-) levels were associated with clinical EPM, suggesting that measurement of CSF NO(x)(-) levels could improve the accuracy of diagnostic tests that are based upon detection of S. neurona-specific Abs in CSF alone and that reduced NO levels could be causally related to the development of EPM.

The role of nitric oxide (NO) in multiple sclerosis (MS) is not clear. We found increased cerebrospinal fluid concentrations of the NO degradation products nitrate (NO(x)) in clinically definite MS but not in clinically isolated syndromes. High CSF concentrations of NO(x) correlated with long attack duration. Patients carrying the truncated CC chemokine receptor allele CCR5 Delta32 had lower serum concentration of NO(x) at later attack stages. NO(x) concentrations did not change after methylprednisolone treatment but high concentrations were associated with more pronounced treatment responses. These findings suggest an association of high CSF levels of NO(x) with more severe disease activity in relapsing-remitting MS.

Tumor necrosis factor (TNF-alpha) and IL-10 are key regulators of the T helper (Th)1/Th2 balance, which is critically skewed in many pathological conditions including immune-mediated inflammatory diseases of central nervous system (CNS) such as multiple sclerosis (MS). Nitric oxide (NO) has been reported to have dual effects on CNS pathology, and to play an important role in MS. We performed a cross-sectional study in 17 randomly selected patients during MS flare-up, and compared levels of TNF-alpha, IL-10 and NO in serum and cerebrospinal fluid (CSF) with the serum values of these mediators in two different control groups, healthy subjects and HIV-infected untreated patients. Serum and CSF values of TNF-alpha, IL-10 and NO were higher in MS patients than in the serum of healthy controls. Two MS patients showed increased levels of NO in CSF, with inversion of the NO(SERUM)/NO(CSF) quotient, which is clearly indicative of an intrathecal production of NO. No correlation among the values of both cytokines and NO, and the laboratory parameters analysed in MS patients (IgG index, presence of IgG oligoclonal bands and albumin quotient) was found. The high levels of TNF-alpha and IL-10 (both in serum and CSF) accompanying an MS attack suggest a simultaneous expression of Th1 and Th2 cytokines as opposed to sequential expression of Th1 followed by Th2 as described in the models of experimental autoimmune encephalomyelitis (EAE). Globally, our results support the inherent heterogeneity of the disease.

We investigated CSF concentrations of nitrite and nitrate as indicators of nitric oxide (NO) production in patients with tetrahydrobiopterin (BH4) deficiencies. Patients with 6-pyruvoyl-tetrahydropterin synthase, sepiapterin reductase and dihydropteridine reductase deficiencies exhibited decreased CSF nitrite + nitrate levels compared with healthy control subjects. Reduced levels of nitrite + nitrate were not influenced by oral administration of 2.5-5.0 mg/kg tetrahydrobiopterin. Our data indicate impaired NO synthase function in patients with BH4 deficiency and suggest possible involvement in the neuronal cell dysfunction.

Objective: To evaluate the relationship between the concentration of nitric oxide (NO) and cytological change in cerebrospinal fluid (CSF) and the onset of neurocysticercosis in patients., Methods: NO Level in CSF was detected in 30 cases of neurocysticercosis, 20 cases of tuberculous meningitis (TBM) and 20 healthy people as control by using Griess method. The cytological components in CSF were also examined., Results and Conclusion: Griess method was proved to be a rapid and accurate technique for the detection of NO content in CSF. The NO concentration in cases of neurocysticercosis and TBM was significantly higher than that of control(P < 0.01). The neurocysticercosis cases showed the highest CST NO level which was considerably higher than that of TBM cases(P < 0.05). Among the cytological changes, the neurocysticercosis cases also showed a higher count of eosinophils than that of TBM cases and control (P < 0.01). The NO level and eosinophils count in CSF increased significantly in patients with neurocysticercosis.

Unlabelled: It is still unclear which neurotransmitters are involved in labor pain. We measured the concentrations of excitatory amino acids, nitric oxide, and prostaglandin E2 in the cerebrospinal fluid (CSF) of pregnant women, particularly in those with labor pain. The patients included in the study consisted of women who underwent cesarean delivery either with labor pain (Labor Pain group, n = 40) or without labor pain (Nonlabor Pain group, n = 58). All patients received spinal anesthesia (intrathecal injection of 10-12 mg of bupivacaine) for the operation, and 2 mL of CSF was collected before bupivacaine injection. Concentrations of aspartate and glutamate (0.50 +/- 0.06 microM and 0.79 +/- 0.10 microM, respectively) were significantly larger in the Labor Pain group than in the Nonlabor Pain group (0.35 +/- 0.03 microM and 0.54 +/- 0.04 microM, P < 0.05). There were no significant differences in the concentrations of nitric oxide and prostaglandin E2 between the groups. A positive correlation was found between CSF concentrations of excitatory amino acids and labor pain., Implications: The excitatory amino acids, aspartate and glutamate, play a role in labor pain. N-methyl-D-aspartate receptor antagonists may be useful for labor pain and postlabor uterine contraction pain relief.

Because nitric oxide (NO) is a putative mediator of oligodendrocyte damage in the primary progressive form of MS (PPMS), the authors analyzed the levels of NO oxidation products in CSF and plasma from 25 patients with PPMS and 15 controls. The levels of nitrite + nitrate (NOx) in CSF were fourfold higher in patients with PPMS than in controls (p < 0.001), whereas the concentrations in plasma were similar. These data suggests involvement of NO in nervous tissue damage in PPMS.

Multiple sclerosis is a disease characterized by perivascular infiltrates and demyelination of the white matter in the central nervous system. In this study, we compared the serum and cerebrospinal fluid nitric oxide levels before and after methylprednisolone therapy, and during remission period, and investigated the relationship of nitric oxide to the activity of multiple sclerosis. Cerebrospinal fluid and serum nitric oxide levels were measured blind as nitrite plus nitrate, using the nitrate reductase and Griess reaction method in 20 patients with multiple sclerosis before and after corticosteroid therapy, and during remission period, and in 20 control subjects. Mean cerebrospinal fluid and serum nitric oxide levels were highest in the pretreatment group and lowest in the control group. There was no correlation with nitric oxide levels in these two groups. Although corticosteroid therapy did not have any great effect on Expanded Disability Status Scales, it led to a decrease in nitric oxide levels. The possible cause of this might be the inhibition of nitric oxide synthesis by methylprednisolone, or a decrease in multiple sclerosis activity. We conclude that serum or cerebrospinal fluid nitric oxide levels do not reflect the activity in multiple sclerosis.

Objective: Nitric oxide (NO) plays an important role in the pathogenesis of neuronal injury after brain ischemia, and decreased levels of NO have been implicated in the pathogenesis of vasospasm after subarachnoid hemorrhage (SAH). In this study, we measured the ventricular cerebrospinal fluid (CSF) NO levels in patients with SAH and correlated the levels with clinical grade and middle cerebral artery velocities measured with transcranial Doppler ultrasound., Methods: All patients with spontaneous SAH documented on computed tomography and with an external ventricular drain inserted within 24 hours of hemorrhage were included in the study. A total of 16 patients were studied between August 1999 and August 2000. CSF was collected serially at the time of surgery and subsequently at daily intervals. It was collected during the time that the external ventricular drain remained patent and in situ. NO levels were measured by photometric analysis by using a nitrite/nitrate assay kit (Cayman Chemical, Ann Arbor, MI)., Results: The peak NO level in patients with SAH ranged from 9.96 to 168.16 micromol, with a median of 36.93 micromol. The levels were significantly elevated as compared with the control group (5.16 micromol, P < 0.05). The median NO level in patients with poor-grade SAH was 67.14 micromol as compared with 27.42 micromol in patients with good-grade hemorrhage (P < 0.05). No correlation was seen between CSF NO levels and middle cerebral artery velocities. The median NO level was 33.2 micromol in patients with a poor outcome as compared with 30.25 micromol in patients with a good outcome (P > 0.05)., Conclusion: This study showed that NO levels are elevated after spontaneous SAH, and the degree of elevation is higher in patients with poor-grade SAH.

We studied total nitric oxide (nitrite + nitrate) (NO) levels in cerebrospinal fluid (CSF) of chronic spinal diseases in nonsmokers (133 patients: 76 men and 57 women; mean age, 63 years; range, 15-92 years) by the Griess method to clarify the role of NO in different spinal diseases. The extent of compression in terms of numbers of disc level at the compressed spinal nerve and neurological evaluation were also assessed according to the Japanese Orthopaedic Association scores. The spinal diseases included cervical myelopathy and radiculopathy (cervical disease group), ossification of yellow ligament (thoracic disease group), and lumbar disc herniation, lumbar canal stenosis and lumbar spondylolisthesis (lumbar disease group). NO levels in the spinal disease groups (4.98+/-2.28 micromol/l: mean +/- SD) were significantly higher than that in the control group (2.53+/-0.94 micromol/l). An inverse correlation was detected between the elevated levels of NO and the grade of clinical symptoms in the cervical disorders. The number of disc level at the compressed spinal nerve was positively correlated with elevated NO levels in CSF in the cervical and lumbar disorder groups. These results indicate that nerve compression may elevate NO levels in CSF, and that NO concentration in the CSF might be a useful marker of damage to nervous system in spinal disorders.

Nitric oxide (NO) has been implicated in the mediation of the neuronal excitotoxic cascade. In order to estimate brain NO production, cerebrospinal fluid (CSF) levels of NO metabolites, nitrates and nitrites (NN(x)) were measured in 31 children with west syndrome (WS) and in 12 controls. There was no age-related change in the NN(x) levels during the first year of life. The mean of the NN(x) levels was significantly higher in patients with WS than in controls (8.43 vs. 5.27 microM; P=0.01). Analysis of the etiological subgroups showed that the patients with a symptomatic etiology of WS had significantly higher NN(x) levels than controls (P<0.005) or than the patients with a cryptogenic etiology. The cryptogenic cases, in turn, did not differ from the controls (P=0.48). Levels of NN(x) were also significantly higher in children with focal brain abnormalities (infarction, atrophy or previous infection) than in those with other abnormalities or with normal neuroradiological findings (P<0.005). No correlation was found between the NN(x) levels and the duration of the symptoms, while paired samples obtained from eight children with WS showed that the NN(x) levels rose significantly (P=0.02) within the first 40 days of symptoms. The levels of NN(x) did not correlate with the CSF levels of neuronal growth factor or with the later decline in mental performance. This study demonstrates that the production of NO can be measured in human epileptic conditions and supports the idea gained from experimental studies that NO is involved in the pathophysiology of epilepsy. However, normal levels of NN(x) in patients with cryptogenic infantile spasms suggest that an increase in NO production be due to the concomitant neuronal damage rather than seizure activity per se. The findings suggest that there are no age-related changes in the NN(x) levels during the first year of life, and that children with symptomatic WS have elevated levels of NN(x), which rise during the first 40 days of symptoms. Although the NN(x) levels cannot be used to estimate the duration of symptoms or to predict the prognosis of mental development, they may support the differentiation of symptomatic from cryptogenic etiologies of WS.

Objective: Nitric oxide (NO), one of the most powerful endogenous vasodilators, is thought to play a major role in the development of delayed vasospasm in patients with subarachnoid hemorrhage (SAH). However, the role of the production of cerebral NO in patients with SAH is not known. In other SAH studies, NO metabolites such as nitrite and nitrate have been demonstrated to be decreased in cerebrospinal fluid and in plasma., Methods: In this study, a microdialysis probe was used, along with a multiparameter sensor, to measure NO metabolites, brain tissue oxygen tension, brain tissue carbon dioxide tension, and pH in the cortex of patients with severe SAH who were at risk for developing secondary brain damage and vasospasm. NO metabolites, glucose, and lactate were analyzed in the dialysates to determine the time course of NO metabolite changes and to test the interrelationship between the analytes and clinical variables., Results: Brain tissue oxygen tension was strongly correlated to dialysate nitrate and nitrite (r2 = 0.326; P < 0.001); however, no correlation was noted between brain tissue oxygen tension and NO metabolites in cerebrospinal fluid (r2 = 0.018; P = 0.734). No significant correlation between NO production, brain tissue carbon dioxide tension, and dialysate glucose and lactate was observed., Conclusion: Cerebral ischemia and compromised substrate delivery are often responsible for high morbidity rates and poor outcomes after SAH. The relationship between brain tissue oxygen and cerebral NO metabolites that we demonstrate suggests that substrate delivery and NO are linked in the pathophysiology of vasospasm after SAH.

This study was undertaken to determine whether or not nitric oxide metabolites (NO(2)(-) plus NO(3)(-): NOx levels) in cerebrospinal fluid (CSF) would be predictors of treatment outcome in patients with degenerative lumbar diseases (DLD) including lumbar disc herniation (LDH) and lumbar spinal canal stenosis (LCS). The NOx levels in CSF were measured using an NO analyzer based on the Griess method. Six healthy volunteers and 18 patients with painless diseases were included in the control group. The pre- and postoperative NOx levels in 25 DLD patients, who underwent herniotomy for LDH (17 patients) or selective decompression for LCS (eight patients), were analyzed. The postoperative follow-up periods were approximately 8 months. Nineteen of 25 DLD patients, whose preoperative NOx levels were two standard deviations higher than the mean NOx levels of an age-matched control group, were included in an NO elevated (NOE) group. Among the 25 DLD patients, the preoperative NOx levels in six patients (young LDH group) were within the normal range. The pain-related Japanese Orthopaedic Association score and the Hirabayashi recovery rate were respectively used to evaluate the pain severity and the degree of pain relief. The preoperative and changes of postoperative NOx levels in the NOE group were negatively correlated with the Hirabayashi recovery rate. Normal postoperative NOx levels and excellent pain relief were achieved in young DLD patients. In conclusion, the preoperative and changes in postoperative NOx levels are quantitative predictors of postoperative pain relief in DLD patients.

Nitrate levels in CSF and sera from 16 coma and 19 noncoma falciparum malaria patients were determined using nitric oxide colorometric assay. The medians (range lower, upper limits) of nitrate in sera of comatose and noncomatose patients were 0.28 (0.11, 1.24) and 0.23 (0.05, 0.87) microM, respectively. The medians of nitrate level in CSF of coma and noncoma cases were 0.09 (0.01, 0.28) and 0.15 (0, 1.18) microM, respectively. There was no difference of nitrate level in sera and CSF from comatose or noncomatose patients compared to that in normal sera and CSF. The amount of nitrate in sera and CSF of both groups was not significantly correlated with coma depth, parasitemia, parasite clearance time and time to recovery. Contrast to our in vitro study using immunoperoxidase staining, we found inducible nitric oside synthase production by brain endothelial cells during 4-24 hours of coculturing with late stage of P. falciparum infected red blood cells. These results suggests that malaria severity can not be differentiated by nitrate level in body fluid.

Objective: To investigate systemic and intrathecal production of proinflammatory cytokines in relation to cerebrospinal fluid (CSF) nitric oxide (NO) release in patients with neuropsychiatric lupus erythematosus (NPLE)., Methods: Thirty patients with NPLE rated as mild, moderate, or severe were studied and CSF was obtained from 21 of these. Cytokine mRNA expressing cells were detected by in situ hybridisation. Soluble cytokines were assessed by enzyme linked immunosorbent assay (ELISA). Nitrite and nitrate were determined by capillary electrophoresis., Results: Patients with NPLE had high numbers of lymphocytes expressing mRNA for tumour necrosis factor alpha (TNFalpha), interferon gamma, and interleukin 10 in blood. The number of peripheral blood TNFalpha mRNA positive cells correlated strongly with the level of NO metabolites in the CSF (r(2)=0.69). Both the number of peripheral blood mononuclear cells expressing mRNA for TNFalpha as well as the CSF level of NO metabolites correlated with NPLE disease severity., Conclusion: These data suggest that increased peripheral production of proinflammatory cytokines such as TNFalpha may contribute both to an increased production of NO in the central nervous system and to generation of clinical NPLE. The data also support the possibility that measurements of NO metabolites in CSF may be of value in the diagnosis of neurological symptoms related to SLE.

A growing body of evidence implicates excessive generation of nitric oxide (NO) within the central nervous system (CNS) in multiple sclerosis (MS). The aim of our study is to analyse nitrite and nitrate as end products of NO in the cerebrospinal fluid (CSF) from MS patients and correlate the concentrations with clinicol characteristics of the disease. CSF nitrite and nitrate concentrations were measured after reduction of nitrate, by Griess reaction, in 105 MS potients, 27 patients with non-inflammatory neurological disorders (NIND) and 13 individuals without neurological disorder (Co). Mean CSF nitrite and nitrate concentrations were significantly higher in patients with MS and NIND compared with the Co patients (9.44 and 8.68, respectively, versus 6.85 microM; P=0.0001 and P=0.031, respectively). There was no significant correlation between CSF nitrite and nitrate concentrations and activity, phase, severity and duration of MS. Our data are in agreement with the results of previous studies which have demonstrated raised concentrations of CSF NO metabolites in MS patients, providing further evidence for NO involvement in MS. The lack of correlation between NO metabolites and disease activity speaks in favour of the possible dual role of NO, as both immunoregulatory and pro-inflammatory molecule, in the pathogenesis of MS.

Objective: To measure cerebrospinal fluid and plasma concentrations of nitrate and nitrite as indicators of nitric oxide production in adults after subarachnoid hemorrhage (SAH)., Design: A prospective, clinical study., Setting: Multidisciplinary intensive care unit., Patients: Nine patients (three males and six females, aged 29-64 yrs) with aneurysm-induced SAH were studied. Glasgow Coma Scale score on admission ranged from 9 to 15. Ruptured aneurysms were clipped within 72 hrs of ictus, and then conventional hypervolemic, hemodilution, and induced hypertension methods were applied., Interventions: None., Measurements and Main Results: Nitrate and nitrite concentrations of patients were examined sequentially by a capillary zone electrophoresis every day for 13 days. As a control group, cerebrospinal fluid was sampled from patients (n = 9, six males and three females, aged 30-60 yrs) without neurologic disorders who underwent spinal taps for spinal anesthesia, and plasma from healthy human volunteers (n = 43, 21 males and 22 females, aged 23-49 yrs). There were no significant differences over time in cerebrospinal fluid nitrate concentrations after SAH. Concentrations of cerebrospinal fluid nitrate after SAH were increased compared with control values. Plasma nitrate concentration was decreased compared with control values, but the value on day 14 was increased significantly (p < .05) compared with those during days 2-11. Plasma and cerebrospinal fluid nitrite concentrations after SAH were similar to those in control subjects. Similar concentrations of nitric oxide metabolite in plasma and cerebrospinal fluid were observed between the patients with and without symptomatic vasospasm., Conclusion: The increase of cerebrospinal fluid nitrate after SAH may attribute to the endogenous nitric oxide production in the injured brain.

A growing body of evidence points out the potential role of inflammatory mechanisms in the pathophysiology of brain damage in dementia. We have recently demonstrated that patients with Alzheimer's disease (AD) and vascular dementia (VaD) display an intrathecal production of proinflammatory cytokines. TNF-alpha, one of these cytokines, leads to the production of nitric oxide (NO), a potent inflammatory mediator, by induction of inducible NO synthase. The aim of the present study was to investigate the intrathecal levels of nitrate, one of the main metabolites of NO, and to relate its levels to the degree of intellectual impairment, in patients with AD and VaD. Twenty patients with early AD and 26 patients with VaD were analyzed with respect to cerebrospinal fluid levels of nitrate by gas chromatography/mass spectrometry. Interestingly, in patients with AD but not VaD, the intrathecal levels of nitrate were significantly and inversely correlated (r = -0.68, p = 0.002) to the degree of intellectual impairment. Our study demonstrates an inverse correlation between the intrathecal levels of nitrate and the degree of cognitive impairment in patients with AD, suggesting a neuroprotective effect of NO in AD., (Copyright 2000 S. Karger AG, Basel)

Brain injury due to bacterial meningitis results in a high mortality rate and significant neurologic sequelae in survivors. The objective of this study was to determine if the application of moderate hypothermia shortly after the administration of antibiotics would attenuate the inflammatory response and increase in intracranial pressure that occurs in meningitis. For this study we used a rabbit model of severe Group B streptococcal meningitis. The first component of this study evaluated the effects of hypothermia on blood-brain barrier function and markers of inflammation in meningitic animals. The second part of the study evaluated the effects of hypothermia on intracranial pressure, cerebral perfusion pressure and brain edema. This study demonstrates that the use of hypothermia preserves CSF/serum glucose ratio, decreases CSF protein and nitric oxide and attenuates myeloperoxidase activity in brain tissue. In the second part of this study we show a decrease in intracranial pressure, an improvement in cerebral perfusion pressure and a decrease in cerebral edema in hypothermic meningitic animals. We conclude that in the treatment of severe bacterial meningitis, the application of moderate hypothermia initiated shortly after antibiotic therapy improves short-term physiologic measures associated with brain injury.

The potential role of inflammatory mechanisms in the pathophysiology of ischemic brain damage has intensely been discussed. We have recently demonstrated that stroke patients display an intrathecal production of proinflammatory cytokines early after onset of symptoms. IL-1beta, one of these cytokines, stimulates the production of nitric oxide (NO), a potent inflammatory mediator. The aim of the present study was to investigate the intrathecal levels of nitrate, one of the main metabolites of NO in acute stroke and to relate its levels to brain damage. Stroke patients were prospectively studied with clinical evaluation, radiological assessment and analysis of intrathecal levels of nitrate by gas chromatography/mass spectrometry. In addition, simultaneous analyses of cytokines and of soluble Fas/APO-1 and bcl-2, two proteins regulating apoptosis, were performed. The intrathecal levels of nitrate were not significantly different in stroke patients compared to controls throughout the observation period. However, the intrathecal levels of nitrate increased significantly 3 months after stroke onset compared with the first 3 days. Interestingly, the levels of nitrate measured at stroke onset were negatively correlated to the final size of infarct volume (r = -0.69, p < 0.05) measured by MRI. In addition, patients with large infarcts displayed significantly (p = 0.008) lower levels of nitrate in cerebrospinal fluid compared to patients with small infarcts during the first 3 days after stroke onset. In contrast, the intrathecal levels of nitrate were significantly positively correlated (r = 0.79, p < 0. 001) to the neurological deficit and negatively correlated (r = -0. 76, p < 0.05) to bcl-2, a protein downregulating neuronal apoptosis, in the late stage of the stroke. Early NO production is associated with a smaller infarct volume, suggesting a protective effect, whereas late NO production is associated with severer neurological deficits, suggesting a neurotoxic effect. Treatment trials pertaining to modulate NO production in stroke should take into consideration the dual effect of NO on ischemic brain damage., (Copyright 2000 S. Karger AG, Basel.)

In order to investigate the potential role of endothelins (ETs) and nitric oxide (NO) in the pathogenesis of multiple sclerosis (MS) we evaluated the levels of these vasoactive mediators in cerebrospinal fluid (CSF) of relapsing remitting MS patients and in a group of subjects with other neurological diseases (OND) and in a control group of subjects without neurological disease. Eighty patients affected from clinically diagnosed MS were selected, 44 of them were studied during an acute clinical attack and 36 in a stable phase. The OND group included 21 subjects affected by degenerative non inflammatory (n=9) and inflammatory (n=12) neurological disease while the control group included 22 subjects with cancer of the prostate (n=11) and with bladder disease (n=11). ET levels were significantly increased in CSF of relapsing remitting MS patients with an acute clinical attack in comparison with those in a stable phase, the OND group and the control group. Moreover significant differences were observed among the four groups with regard to the NO levels: MS patients in a stable and acute phase like OND group have high levels of NO compared to the control group. Since the blood-brain barrier index values did not differ significantly between the three groups, the data of this study suggest an important role for NO and ET in cerebral microcirculation in MS patients.

To investigate the content and dynamics of nitric oxide (NO) in the cerebrospinal fluid (CSF) of patients with acute head injury and to clarify the relationship of NO with clinical features and intracranial pressure (ICP) as well as outcomes, 38 adults with acute head injury were studied. Glasgow Coma Scale (GCS) obtained at admission and Glasgow Outcome Scale (GOS) 3 months after injury was assessed. ICP was surveyed via intraventricular catheter and lumbar puncture and CSF samples were obtained simultaneously. NO was determined with Griess reagents. Results showed that NO peak content in the head injury group was significantly higher than that of the control group. During dynamic research, no peak content of mildly injured cases and severely injured ones appeared in different time windows respectively. The peak value of NO was distinctly higher in the severe group than in the mild group. NO peak value of the raised ICP group was remarkably higher than that of the normal ICP group. The peak value of NO was considerately higher in the poor outcome group than in the good outcome group. When the content of NO was over 6.5 mumol/L, the rate of poor outcome was increased. There existed a correlation between NO and GCS, ICP and GOS. It is concluded that the content of NO was increased in patients with acute head injury and the changes of NO had different time windows in severely injured patients and mildly injured ones. The more sever the injury, the higher the NO content; and the more serious the secondary brain injury and brain edema, the worse the outcomes. When NO is combined with GCS, GOS and ICP, it increases the accuracy of judgement to the degree of head injury and outcome.

Effect of nitric oxide (NO) on vasomotor tone of cerebral parenchymal arterioles was studied in rats. Then, the role of NO was clinically investigated in the pathogenesis of progressive cerebral vascular occlusive disease, moyamoya disease. In rat, the cerebral arterioles, about 30-60 microm in diameter, were dilated by L-arginine, a precursor of NO, at concentrations as low as 0.1 micromol with maximal dilation of 14% at 100 micromol. The arterioles were constricted by N(G)-monomethyl-L-arginine (L-NMMA), a NO synthesis inhibitor. Superoxide dismutase, which seems to protect NO from inactivation, increased sensitivity of L-arginine. Compared with control specimens of cerebral spinal fluid (CSF) obtained from 16 patients, concentrations NO metabolites in the CSF of 23 patients with moyamoya disease were significantly higher. NO metabolites concentrations obtained during initial surgery decreased during a second, contralateral procedure. NO plays an important role in the regulation of basal tone of cerebral parenchymal arterioles and contributes to the increase in collateral circulation in cerebral occlusive disease like moyamoya disease. Vascular bypass surgery can reduce NO metabolites together with abnormal collateral circulation.

Background: To investigate whether nitric oxide (NO) contributes to formation of abnormal collateral circulation in patients with moyamoya disease., Methods: Cerebrospinal fluid (CSF) samples were obtained from the subarachnoid space of the Sylvian fissure during combined bypass surgery for moyamoya disease and kept frozen until NO metabolites, nitrate and nitrite, were measured using a Griess method., Results: Compared with control CSF obtained from 18 patients with hemifacial spasm, unruptured aneurysm, etc., concentrations of NO metabolites in 26 CSF samples of 18 patients with moyamoya disease were significantly higher (mean +/- SE; 17.6 +/- 1.2 vs. 10.5 +/- 1.0 microM, p < 0.01). In eight patients, the CSF samples from both the first and second operation could be obtained. NO metabolite concentrations (20.5 +/- 2.3 microM) in CSF obtained from the first surgery decreased to 15.7 +/- 1.8 microM (p < 0.01) in CSF obtained from the second, contralateral procedure. The cases of moyamoya disease with greater development of moyamoya vessels at angiographic stage 3 and 4 tended to show higher concentrations of NO metabolites than cases at earlier or later stages with a few moyamoya vessels., Interpretation: Nitric oxide concentrations in CSF are chronically elevated in moyamoya disease, probably reflecting development of abnormal collateral circulation. i.e. moyamoya vessels. Vascular bypass surgery can reduce abnormal collateral circulation with reduced production of nitric oxide.

Nitric oxide is very likely to play a role in physiopathological mechanisms of bacterial meningitis. As shown by in vitro studies, nitric oxide is toxic to endothelial cells, as well as to neurones, and thus may be responsible for neurological sequelae in bacterial meningitis. Increased level of nitric oxide can also inhibit mitochondrial respiration, enhancing anaerobic glycolysis. Twenty-seven children with documented bacterial meningitis, 73 with viral (mumps and enteroviral) meningitis, and 51 controls were studied. All children with bacterial meningitis were given cefotaxime (200 mg/kg per day). Glucose and protein concentrations and cerebrospinal fluid cell counts were determined routinely, as well as nitrite and nitrate levels. The levels of nitrite and nitrate in cerebrospinal fluid on admission were higher in patients with bacterial meningitis than in controls or in children with viral meningitis. In 10 patients, dexamethasone therapy (0.4 mg/kg every 12 h for 2 days) was started about 10 min before the first antibiotic dose. A significantly lower nitrite concentration was observed after 24-48 h of treatment compared with non-steroid-treated patients. Significant positive correlations between the nitrite and granulocyte counts and the protein concentration in cerebrospinal fluid were found in all patients with meningitis. Increased nitric oxide production in cerebrospinal fluid during the acute phase of bacterial meningitis may result from the inflammatory process and tissue injury. Dexamethasone administered before the first parenteral antibiotic dose seems to reduce nitric oxide production in the cerebrospinal fluid during bacterial meningitis.

Background: Increasing evidence has suggested the possibility that the activation of N-methyl-D-aspartate (NMDA) receptors modulates spinal nociceptive transmission via a nitric oxide (NO)/cyclic guanosine 3',5'-monophosphate (cGMP) pathway. However, the existence and the role of an NO/cGMP pathway in the modulation of spinal nociceptive transmission has been unclear. The authors hypothesized that the activation of NMDA receptors stimulates an NO/cGMP pathway, and this pathway evokes glutamate release within the spinal cord, modulating spinal nociceptive transmission., Methods: The authors have examined the effects of an NO synthase inhibitor and a soluble guanylate cyclase inhibitor on the concentrations of NO metabolites (NO2-/NO3-) and glutamate in the cerebrospinal fluid after intrathecal perfusion of NMDA, concomitantly observing pain-related behavior (scratching, biting, and vocalization) in unanesthetized, free-moving rats using an intrathecal microdialysis method. The contents of cGMP in the dorsal horn were also measured using enzyme immunoassay method., Results: Intrathecal perfusion of NMDA produced pain-related behavior and increased glutamate and NO2-/NO3-concentrations in a dose-dependent manner. A competitive NMDA receptor antagonist, D,L-2-amino-5-phosphonovaleric acid, completely blocked the NMDA-induced responses. An NO synthase inhibitor, N(G)-monomethyl-L-arginine acetate, at a dose that completely blocked the increase in NO2-/NO3-, inhibited both the NMDA-induced pain-related behavior and the increase in glutamate concentration. In addition, a soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazole[4,3-a]quinoxaline-1-one, also inhibited significantly NMDA-induced pain-related behavior and the increase in glutamate concentration. NMDA induced an increase in cGMP in the dorsal half of the spinal cord, which was blocked by N(G)-monomethyl-L-arginine acetate., Conclusions: The results of this study support the hypothesis that the activation of NMDA receptors modulated pain-related behavior via an NO/cGMP/glutamate release cascade within the spinal cord.

Hypoxic-ischemic encephalopathy (HIE) is the result of a chain of events caused mainly by cytokines and nitric oxide (NO) release, which is later on followed by free oxygen radical injury. To investigate NO involvement in asphyxiated newborns, serum and cerebrospinal fluid (CSF) values of NO levels in 17 neonates with HIE were detected. Infants at or above 37 weeks of gestation were classified to have mild, moderate and severe HIE due to Sarnat and Sarnat. Samples obtained between 24 and 72 h of life were immediately frozen at -70 degrees C till the time of measurement by Sievers NOA. Five patients had mild, 6 patients had moderate and 6 patients had severe HIE, 4 in the severe HIE group also had multisystem involvement. The CSF NO levels were significantly higher in moderate and severe HIE groups compared to the mild HIE group (p = 0.028 and p = 0.018 respectively). Our results show that NO level increases in CSF with the severity of HIE between 24 and 72 h following asphyxia. According to the animal work, this is the time period where inducible NO synthase gets activated and could cause neurotoxicity, which might perhaps be prevented by interventions.

Nitric oxide is formed from L-arginine by a family of enzymes: nitric oxide synthase (NOS). The inducible nitric oxide synthase is activated by cytokines and it has been suggested that activation of the enzyme gives rise to neurotoxic levels of reactive nitrogen oxides. This enzyme has been shown to be localized in multiple sclerosis (MS) lesions but the role of nitric oxide formation in the pathogenesis of MS is still unclear. Using capillary electrophoresis, we have analysed nitrite and nitrate in cerebrospinal fluid (CSF) and demonstrate increased levels of reactive nitrogen products in 17 patients with MS. The total levels of oxidized nitrogen products were significantly elevated in MS patients when compared with controls. In patients with active MS, nitrite levels were significantly increased when compared with controls and patients in remission. This is supportive of NOS induction in MS. We suggest that capillary electrophoresis analysis of nitrite and nitrate in CSF could provide a clinically useful way to determine disease activity in MS., (Copyright Lippincott Williams & Wilkins)

The production of nitric oxide (NO) by macrophages is important for the killing of intracellular pathogens, such as Toxoplasma gondii. Gamma interferon (IFN-gamma) and lipopolysaccharide stimulate NO production. The aim of this study was to investigate the importance of NO, IFN-gamma and interleukin-12 (IL-12) in the host immune response in AIDS patients suffering from toxoplasmic encephalitis (TE). It was demonstrated that the production of NO, detected as nitrite/nitrate in the sera and in the cerebrospinal fluid (CSF) of 32 AIDS patients with TE, was normal. In addition, levels of IFN-gamma in the sera and in the CSF of patients with TE were not increased. In contrast, serum levels of IL-12 in these patients were significantly increased (6.5 +/- 7.1 pg/ml; P = 0.0368), compared to the control patients (1.7 +/- 3.5 pg/ml). Furthermore, increased but not significant levels of IL-12 were also observed in the CSF of patients with TE (2.2 +/- 4.7 pg/ml; controls: 0.5 +/- 1.9 pg/ml). The results of this study indicate that reactivation or recurrence of T. gondii infection in HIV-1-infected patients is probably due to a down-regulation of IFN-gamma along with a resulting non-optimal NO activity.

To determine the role of free radical mechanisms in the pathogenesis of amyotrophic lateral sclerosis (ALS), cerebrospinal fluid concentrations of oxidized nitric oxide (NO) products (nitrite and nitrate) and reduced and oxidized forms of glutathione (GSH and GSSG, respectively) were compared between patients with the sporadic form of ALS (SALS) and controls. In the SALS patients, the nitrate levels were significantly higher (by 73%) in contrast to remarkably lower GSSG/GSH ratio, approximately 3-fold, compared to controls. These results suggest that NO production or oxidation is activated in SALS patients, leading to a decrease in superoxide radicals to oxidize GSH. The subsequent generation of a highly reactive anion, peroxynitrite, may play a causal role in the pathogenesis of SALS.