Plasma neurological biomarkers as a measure of neurotoxicity in pediatric dental general anesthesia: a prospective observational feasibility study

PURPOSE

Neurotoxicity concerns have been raised over general anesthesia and sedation medication use in children. Such concerns are largely based on animal studies, historical anesthetic agents, and assessment tools, thus warranting further investigations. Blood biomarkers in detecting neuronal inflammation and apoptosis are novel methods for detecting neuronal damage. Therefore, the aim of this feasibility study was to assess the usefulness of the levels of four plasma biomarkers in dental general anesthesia (DGA) as surrogate markers of neurotoxicity in children. The secondary aim was to compare changes in motor manipulative skills pre- and post-anesthetic exposure.

METHODS

This single-center prospective observational study included 22 healthy children aged between 3 and 6 years old who underwent DGA. Subclinical neurotoxicity was measured with a panel of four plasma biomarkers: Caspase-3, neuron-specific enolase (NSE), neurofilament light chain, and S100B at three time points (1; at start, 2; end and 3; on recovery from DGA). The Skillings-Mack test was used to identify the difference in the biomarker levels at three time points. Motor manipulative score assessment, prior and two weeks after DGA was also performed.

RESULTS

A total of 22 study participants (mean age = 5 ± 1 years) were included with a median DGA duration of 106 ± 28 min. A reduction in Caspase-3 levels was recorded, with pairwise comparison over three time points, reporting a statistical significance between time point 2 vs. 1 and time point 3 vs. 1. Although fluctuations in NSE levels were recorded, no significant changes were found following pairwise comparison analysis. Among other biomarkers, no significant changes over the three periods were recorded. Furthermore, no significant changes in manipulative motor scores were reported.

CONCLUSION

Caspase-3 reduced significantly in the short time frames during day-care DGA; this might be due to the relatively short anesthesia duration associated with dental treatment as compared with more extensive medical-related treatments. Therefore, further studies on Caspase-3 as a potential biomarker in pediatric DGA neurotoxicity are required to further ascertain results of this study.

Neuroglobin alleviates arsenic-induced neuronal damage

People who drink water contaminated with arsenic for a long time develop neuritis, cerebellar symptoms, and deficits in memory and intellectual function. Arsenic induces oxidative stress and promotes apoptosis through multiple signalling pathways in nerve cells. Neuroglobin (Ngb), as a key mediator, is considered to be protective against oxidative stress. In this study, we aimed to study the effects of Ngb knockdown in arsenite-treated rat neurons on levels of apoptosis markers and reactive oxygen species and serum Ngb levels of subjects from arsenic-endemic regions in China. We discovered that arsenic-induced apoptosis and reactive oxygen species production were enhanced in Ngb-knocked-down rat neurons. Silencing of Ngb aggravated the arsenic-induced decrease in the rate of Bcl-2/Bax and the levels of Bcl-2 protein following arsenite treatment. The results also showed that serum Ngb levels were independently negatively correlated with arsenic concentration in drinking water. Furthermore, the serum Ngb levels of four groups (245 individuals) according to different degree exposure to arsenic were 815.18 ± 89.52, 1247.97 ± 117.18, 774.79 ± 91.55, and 482.72 ± 49.30 pg/mL, respectively. Taken together, it can be deduced that Ngb has protective effects against arsenic-induced apoptosis by eliminating reactive oxygen species.

Neurofilament light chain: a specific serum biomarker of axonal damage severity in rat models of Chemotherapy-Induced Peripheral Neurotoxicity

Chemotherapy-Induced Peripheral Neurotoxicity (CIPN) is a severe and long-lasting side effect of anticancer therapy, which can severely impair patients' quality of life. It is a sensory and length-dependent neuropathy, which predominantly affects large myelinated fibers. Easy and reliable monitoring of CIPN in patients is still an unmet clinical need. Since increasing clinical evidence supports the potential use of neurofilament light chain (NfL) as a biomarker of axonal injury, in this study we measured serum NfL levels in animals chronically treated with cisplatin (CDDP) and paclitaxel (PTX), two antineoplastic drugs with different neuronal targets. Wistar rats were treated with CDDP (2 mg/kg i.p. twice/week for 4 weeks) or PTX (10 mg/kg i.v. once/week for 4 weeks). Repeated serum NfL quantification was obtained using the Single Molecule Array (Simoa) technology. The onset and progression of peripheral neurotoxicity were evaluated through neurophysiology, morphological assessments and intraepidermal nerve fibers density quantification. Our results showed that serum NfL measurements correlated with the severity of axonal damage. In fact, both treatments induced serum NfL increase, but higher levels were evidenced in PTX-treated animals, compared with CDDP-treated rats, affected by a milder neurotoxicity. Notably, also the timing of the NfL level increase was associated with the severity of morphological and functional alterations of axonal structure. Therefore, NfL could be a useful biomarker for axonal damage in order to follow the onset and severity of axonal degeneration and possibly limit the occurrence of serious PNS disease.

Delayed LY333013 (Oral) and LY315920 (Intravenous) Reverse Severe Neurotoxicity and Rescue Juvenile Pigs from Lethal Doses of Micrurus fulvius (Eastern Coral Snake) Venom

OBJECTIVE

There is a clear, unmet need for effective, lightweight, shelf-stable and economical snakebite envenoming therapies that can be given rapidly after the time of a snake's bite and as adjuncts to antivenom therapies in the hospital setting. The sPLA2 inhibitor, LY315920, and its orally bioavailable prodrug, LY333013, demonstrate surprising efficacy and have the characteristics of an antidote with potential for both field and hospital use.

METHODS

The efficacy of the active pharmaceutical ingredient (LY315920) and its prodrug (LY333013) to treat experimental, lethal envenoming by Micrurus fulvius (Eastern coral snake) venom was tested using a porcine model. Inhibitors were administered by either intravenous or oral routes at different time intervals after venom injection. In some experiments, antivenom was also administered alone or in conjunction with LY333013.

RESULTS

14 of 14 animals (100%) receiving either LY315920 (intravenous) and/or LY333013 (oral) survived to the 120 h endpoint despite, in some protocols, the presence of severe neurotoxic signs. The study drugs demonstrated the ability to treat, rescue, and re-rescue animals with advanced manifestations of envenoming.

CONCLUSIONS

Low molecular mass sPLA2 inhibitors were highly effective in preventing lethality following experimental envenoming by M. fulvius. These findings suggest the plausibility of a new therapeutic approach to snakebite envenoming, in this example, for the treatment of a coral snake species for which there are limitations in the availability of effective antivenom.

Hesperidin, a citrus flavonoid, protects against l-methionine-induced hyperhomocysteinemia by abrogation of oxidative stress, endothelial dysfunction and neurotoxicity in Wistar rats

CONTEXT

Hesperidin (HSP), a flavanoglycone found in citrus fruits, has antioxidant, anti-inflammatory and neuroprotective properties.

OBJECTIVE

This study evaluates the protective effect of HSP on l-methionine-induced hyperhomocysteinemia (HHcy) in rats.

MATERIALS AND METHODS

Male Wistar rats were randomly divided into seven groups as DMSO, l-methionine, HSP (25, 50 and 100 mg/kg), HSP-per se (100 mg/kg) and donepezil (0.1 mg/kg). HHcy was induced by oral administration of l-methionine (1.7 g/kg) for 32 days. From the 14^th day of study HSP (25, 50 and 100 mg/kg) and donepezil was administered orally to l-methionine-treated rats. Cognitive impairment induced by HHcy was determined using the Morris water maze (MWM) and Y-maze on video tracking system (28^th-32^nd day). Different biomarkers of HHcy in serum and brain and vascular reactivity were evaluated and histopathology (thoracic aorta and brain) was done.

RESULTS

HSP (100 mg/kg) treatment in l-methionine-treated rats exhibited significant (p < 0.001) dose-dependent activity and reduced behavioural deficits, brain acetylcholinesterase (25.99 ± 2.36 versus 10.73 ± 1.26 μmoles/mg), brain lipid peroxidation (15.25 ± 1.65 versus 6.18 ± 0.74 nM/mg), serum homocysteine (Hcy) (22.37 ± 0.30 versus 11.01 ± 1.01 μg/mL) and serum cholesterol (182.7 ± 2.15 versus 101.5 ± 2.76 mg/dL) and increased brain antioxidant levels. HSP significantly (p < 0.001) reduced endothelial dysfunction (ED) by abolishing the effect of l-methionine on acetylcholine-induced endothelial-dependent relaxation and increased serum nitrite and vascular nitric oxide bioavailability along with the restoration of histological aberrations.

CONCLUSION

HSP exerts a protective effect on HHcy by abrogating oxidative stress, ED and neurotoxicity.

Preparation of five 3-MCPD fatty acid esters, and the effects of their chemical structures on acute oral toxicity in Swiss mice

BACKGROUND

3-monochloro-1, 2-propanediol fatty acid esters (3-MCPDEs) comprise a group of food toxicants formed during food processing. 3-MCPDEs have received increasing attention concerning their potential negative effects on human health. However, reports on the toxicity of 3-MCPD esters are still limited. To determine the effects of fatty acid substitutions on the toxicity of their esters, 1-stearic, 1-oleic, 1-linoleic, 1-linoleic-2-palmitic and 1-palmitic-2-linoleic acid esters of 3-MCPD were synthesized and evaluated with respect to their acute oral toxicities in Swiss mice.

RESULTS

3-MCPDEs were obtained through the reaction of 3-MCPD and fatty acid chlorides, and their purities and structures were characterized by ultraperformance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS), infrared, ¹ H and ¹³ C spectroscopic analyses. Medial lethal doses of 1-stearic, 1-oleic, 1-linoleic, 1-linoleic-2-palmitic and 1-palmitic-2-linoleic acid esters were 2973.8, 2081.4, 2016.3, 5000 and > 5000 mg kg^-1 body weight. For the first time, 3-MCPDEs were observed for their toxic effects in the thymus and lung. In addition, major histopathological changes, as well as blood urea nitrogen and creatinine, were examined for mice fed the five 3-MCPDEs.

CONCLUSION

The results from the present study suggest that the degree of unsaturation, chain length, number of substitution and relative substitution locations of fatty acids might alter the toxicity of 3-MCPDEs. © 2016 Society of Chemical Industry.

Neurotoxicity and low paclitaxel clearance associated with concomitant clopidogrel therapy in a 60-year-old Caucasian woman with ovarian carcinoma

AIM

The aim of the present case report was to describe a novel pharmacokinetic drug–drug interaction between the antiplatelet agent clopidogrel and the antineoplastic agent paclitaxel.

METHODS

The patient was identified in a previously described cohort of 93 patients with ovarian carcinoma treated with paclitaxel. The effect of clopidogrel acyl-β-D-glucuronide on the metabolism of paclitaxel was assessed in human liver microsomes. The analysis of clopidogrel in plasma and the quantification of paclitaxel and 6-hydroxypaclitaxel in in vitro samples were performed by liquid chromatography tandem mass spectrometry.

RESULTS

The patient was a 60-year-old female treated with an unknown dose of clopidogrel at the time of paclitaxel therapy. Clopidogrel was present in all three of the plasma samples obtained during paclitaxel dosing. Estimated unbound paclitaxel clearance was 238 l h−1, which was only 62% of the cohort geometric mean (385 l h−1; range 176–726). She was hospitalized three times, developed severe neuropathy and paclitaxel treatment was subsequently discontinued. In vitro, 30-min preincubation with 100 μM clopidogrel acyl-β-D-glucuronide inhibited the depletion rate of 0.5 μM paclitaxel by 51% and the formation rate of 6-hydroxypaclitaxel by 77%.

CONCLUSION

This is the first report of a clopidogrel–paclitaxel interaction, suggesting that clinically used doses of clopidogrel can reduce the cytochrome P450 2C8 (CYP2C8)-mediated systemic clearance of paclitaxel, leading to an increased risk of paclitaxel toxicity. Caution should be exercised whenever the simultaneous use of paclitaxel and clopidogrel cannot be avoided.

Possible peripheral markers for chronic aluminium toxicity in Wistar rats

This investigation gives detailed analysis of peripheral marker enzymes as well as neurobehavioral tests following chronic aluminium (Al) exposure (10 mg/kg b.w. for 12 weeks intragastrically). We observed a significant decrease in the levels of serum cholinesterase after toxicity. The enzymatic activity of cytochrome oxidase (CO), the terminal enzyme of the electron transport chain, was significantly diminished and that of glucose-6-phosphate dehydrogenase (G-6-PD) was significantly enhanced. Neuromuscular co-ordination was assessed using motor and memory function tests. Deficits were observed suggesting a probable model for chronic Al neurotoxicity.

Initial Serum Ammonia as a Predictor of Neurologic Complications in Patients with Acute Glufosinate Poisoning

PURPOSE

Glufosinate poisoning can cause neurologic complications that may be difficult to treat due to delayed manifestation. Studies assessing possible predictors of complications are lacking. Although serum ammonia level is a potential predictor of severe neurotoxicity, it has only been assessed via case reports. Therefore, we investigated factors that predict neurologic complications in acute glufosinate-poisoned patients.

MATERIALS AND METHODS

We conducted a retrospective review of 45 consecutive glufosinate-poisoning cases that were diagnosed in the emergency department (ED) of Wonju Severance Christian Hospital between May 2007 and July 2014. Patients with a Glasgow Coma Scale (GCS) score of <8, seizure, and/or amnesia were defined to a neurologic complication group.

RESULTS

The neurologic complication group (29 patients, 64.4%) comprised patients with GCS<8 (27 patients, 60.0%), seizure (23 patients, 51.1%), and amnesia (5 patients, 11.1%). Non-neurologic complications included respiratory failure (14 patients, 31.1%), intubation and ventilator care (23 patients, 51.1%), shock (2 patients, 4.4%), pneumonia (16 patients, 35.6%), acute kidney injury (10 patients, 22.2%), and death (4 patients, 8.9%). Complications of GCS<8, seizure, respiratory failure, and intubation and ventilator care appeared during latent periods within 11 hrs, 34 hrs, 14 hrs, and 48 hrs, respectively. Initial serum ammonia was a predictor of neurologic complications [odds ratio 1.039, 95% confidence interval (1.001-1.078), p=0.046 and area under the curve 0.742].

CONCLUSION

Neurologic complications developed in 64.4% of patients with acute glufosinate poisoning. The most common complication was GCS<8. Initial serum ammonia level, which can be readily assessed in the ED, was a predictor of neurologic complications.

Altered mental status and end organ damage associated with the use of gacyclidine: a case series

INTRODUCTION

Over the past decade, there has been a sharp increase in the number of newly identified synthetic drugs. These new drugs are often derivatives of previously abused substances but have unpredictable toxicity. One of these drugs is gacyclidine, a derivative of phencyclidine (PCP). Gacyclidine has been studied as a neuroprotective agent in trauma and as a therapy of soman toxicity. There are no previous reports of its use as a drug of abuse.

CASE REPORTS

During a two-month period in the summer of 2013, a series of patients with severe agitation and end-organ injury were identified in an urban academic Emergency Department (ED). A urine drug of abuse screen was performed on all patients, and serum samples were sent for comprehensive toxicology analysis. A total of five patients were identified as having agitation, rhabdomyolysis, and elevated troponin (Table 1). Three of the five patients reported use of methamphetamine, and all five patients had urine drug screens positive for amphetamine. Comprehensive serum analysis identified methamphetamine in three cases, cocaine metabolites in one case, and a potential untargeted match for gacyclidine in all five cases. No other drugs of abuse were identified.

DISCUSSION

This is the first series of cases describing possible gacyclidine intoxication. The possible source of the gacyclidine is unknown but it may have been an adulterant in methamphetamine as all patients who were questioned reported methamphetamine use. These cases highlight the importance of screening for new drugs of abuse when patients present with atypical or severe symptoms. Gacyclidine has the potential to become a drug of abuse both by itself and in conjunction with other agents and toxicity from gacyclidine can be severe. It is the role of the medical toxicology field to identify new agents such as gacyclidine early and to attempt to educate the community on the dangers of these new drugs of abuse.

Association of blood lead level with neurological features in 972 children affected by an acute severe lead poisoning outbreak in Zamfara State, northern Nigeria

BACKGROUND

In 2010, Médecins Sans Frontières (MSF) investigated reports of high mortality in young children in Zamfara State, Nigeria, leading to confirmation of villages with widespread acute severe lead poisoning. In a retrospective analysis, we aimed to determine venous blood lead level (VBLL) thresholds and risk factors for encephalopathy using MSF programmatic data from the first year of the outbreak response.

METHODS AND FINDINGS

We included children aged ≤5 years with VBLL ≥45 µg/dL before any chelation and recorded neurological status. Odds ratios (OR) for neurological features were estimated; the final model was adjusted for age and baseline VBLL, using random effects for village of residence. 972 children met inclusion criteria: 885 (91%) had no neurological features; 34 (4%) had severe features; 47 (5%) had reported recent seizures; and six (1%) had other neurological abnormalities. The geometric mean VBLLs for all groups with neurological features were >100 µg/dL vs 65.9 µg/dL for those without neurological features. The adjusted OR for neurological features increased with increasing VBLL: from 2.75, 95%CI 1.27-5.98 (80-99.9 µg/dL) to 22.95, 95%CI 10.54-49.96 (≥120 µg/dL). Neurological features were associated with younger age (OR 4.77 [95% CI 2.50-9.11] for 1-<2 years and 2.69 [95%CI 1.15-6.26] for 2-<3 years, both vs 3-5 years). Severe neurological features were seen at VBLL <105 µg/dL only in those with malaria.

INTERPRETATION

Increasing VBLL (from ≥80 µg/dL) and age 1-<3 years were strongly associated with neurological features; in those tested for malaria, a positive test was also strongly associated. These factors will help clinicians managing children with lead poisoning in prioritising therapy and developing chelation protocols.

[Homeostasis changes during rehabilitation period after acute chemical poisoning]

The article deals with review of 78 patients of rehabilitation toxicological unit. The patients received resuscitation and detoxification. All patients were divided into three groups; 1st group--patients after poisoning with psychopharmaceuticals, 2nd group--patients after poisoning with cauterizing liquids and 3rd group--patients with encephalopathy after poisoning with neurotoxin (psychopharmaceuticals, narcotics and ethanol). Disorders of rheology, haemostasis and endotoxicosis accrued in all groups. These disorders were a signs of the erythrocytes and platelets aggregation developing and viscoelasticity disorder. Homeostasis changes during rehabilitation period need an accurate diagnostics for purposeful treatment of the defined disorders.

Platelet oxygen consumption as a peripheral blood marker of brain energetics in a mouse model of severe neurotoxicity

Interactions of chemicals with cerebral cellular systems are often accompanied by similar changes involving components in non-neural tissues. On this basis, indirect strategies have been developed to investigate neural cell function parameters by methods using accessible cells, including platelets and/or peripheral blood lymphocytes. Therefore, here it was investigated whether peripheral blood markers may be useful for assessing the central toxic effects of methylmercury (MeHg). For this purpose, we investigated platelet mitochondrial physiology in a well-established mouse model of MeHg-induced neurotoxicity, and correlated this peripheral activity with behavioural and central biochemical parameters. In order to characterize the cortical toxicity induced by MeHg (20 and 40 mg/L in drinking water, 21 days), the behavioral parameter namely, short-term object recognition, and the central mitochondrial impairment assessed by measuring respiratory complexes I-IV enzyme activities were determined in MeHg-poisoned animals. Neurotoxicity induced by MeHg exposure provoked compromised cortical activity (memory impairment) and reduced NADH dehydrogenase, complex II and II-III activities in the cerebral cortex. These alterations correlated with impaired systemic platelet oxygen consumption of intoxicated mice, which was characterized by reduced electron transfer activity and uncoupled mitochondria. The data brought here demonstrated that impaired systemic platelet oxygen consumption is a sensitive and non-invasive marker of the brain energy deficits induced by MeHg poisoning. Finally, brain and platelets biochemical alterations significantly correlated with cognitive behavior in poisoned mice. Therefore, it could be proposed the use of platelet oxygen consumption as a peripheral blood marker of brain function in a mouse model MeHg-induced neurotoxicity.

Contribution of single-minded 2 to hyperglycaemia-induced neurotoxicity

Diabetes mellitus is associated to central nervous system damage, which results in impairment of brain functions and cognitive deficits and decline in memory. However, the mechanisms mediating the actions of glucose on the neurons remained elusive. Single-minded 2 (Sim2), a basic helix-loop-helix (bHLH)-PAS transcriptional repressor, is thought to be involved in some symptoms of Down syndrome. We hypothesized that Sim2 mediated hyperglycaemia-induced neuronal injury and impairment of learning and memory. It was found that expression of Sim2 protein in cortical neurons was increased in streptozotocin-induced diabetes mellitus rat model. Drebrin, down-regulated by Sim2, was subsequently decreased as detected by confocal laser scanning microscopy and Western blot analysis. The expression pattern of Sim2 and Drebrin correspond to 50mmol/L glucose (hyperglycaemia) was also found in primary cultured neurons. Curcumin, one neuroprotective agent, inhibited hyperglycaemia-induced neurotoxicity. Moreover, curcumin alleviated Sim2 expression, and reversely raised Drebrin expression in neurons treated with hyperglycaemia. Finally, we found that silencing Sim2 expression decreased hyperglycaemia-induced neuronal injury. In conclusion, Sim2 may mediate neurotoxicity during hyperglycaemia and thereby play a critical role in the development of hyperglycaemia-induced cognitive deficits.

[Pharmacological treatment of hemorheological disorders in children with acute respiratory viral infection]

This article presents the results of monitoring in a group of children with severe forms of acute respiratory viral infection and toxic encephalopathy. Hemorheological disorder in the form of hyperviscosity syndrome has been detected in all patients with severe forms of acute respiratory viral infection. It was suggested the inclusion of cytoflavin in the complex therapy for correcting the hemorheological status. The administration of cytoflavin led to reduction of erythrocyte aggregation and general improvements in rheological indices of children with severe forms of acute respiratory viral infection and toxic encephalopathy.

Autoantibodies to nervous system-specific proteins are elevated in sera of flight crew members: biomarkers for nervous system injury

This descriptive study reports the results of assays performed to detect circulating autoantibodies in a panel of 7 proteins associated with the nervous system (NS) in sera of 12 healthy controls and a group of 34 flight crew members including both pilots and attendants who experienced adverse effects after exposure to air emissions sourced to the ventilation system in their aircrafts and subsequently sought medical attention. The proteins selected represent various types of proteins present in nerve cells that are affected by neuronal degeneration. In the sera samples from flight crew members and healthy controls, immunoglobin (IgG) was measured using Western blotting against neurofilament triplet proteins (NFP), tubulin, microtubule-associated tau proteins (tau), microtubule-associated protein-2 (MAP-2), myelin basic protein (MBP), glial fibrillary acidic protein (GFAP), and glial S100B protein. Significant elevation in levels of circulating IgG-class autoantibodies in flight crew members was found. A symptom-free pilot was sampled before symptoms and then again afterward. This pilot developed clinical problems after flying for 45 h in 10 d. Significant increases in autoantibodies were noted to most of the tested proteins in the serum of this pilot after exposure to air emissions. The levels of autoantibodies rose with worsening of his condition compared to the serum sample collected prior to exposure. After cessation of flying for a year, this pilot's clinical condition improved, and eventually he recovered and his serum autoantibodies against nervous system proteins decreased. The case study with this pilot demonstrates a temporal relationship between exposure to air emissions, clinical condition, and level of serum autoantibodies to nervous system-specific proteins. Overall, these results suggest the possible development of neuronal injury and gliosis in flight crew members anecdotally exposed to cabin air emissions containing organophosphates. Thus, increased circulating serum autoantibodies resulting from neuronal damage may be used as biomarkers for chemical-induced CNS injury.

[Immune system disorders and their correction in critically ill patients with toxic and hypoxic encephalopathy]

In this article there are materials, which were received in the process of treatment of 69 patients with azaleptin (leponeks) acute severe poisonings. The immunologic research has shown that the first phase of acute poisonings in patients with toxicohypoxic encephalopathy is accompanied by severe immune alterations. The alterations of proinflammation and antiinflammation cytokines have been investigated and its increase has not been revealed. It was shown, that the employment of citoflavin in intensive therapy of acute poisonings leads to decrease of the level of immunosupression.

Thyroid dysfunction as a mediator of organochlorine neurotoxicity in preschool children

BACKGROUND

Exposure to organochlorine compounds (OCs) can alter thyroid function in humans, and hypothyroidism during early life can adversely affect a child's neurodevelopment.

OBJECTIVES

In this study we aimed to assess the relationship between developmental organochlorine exposures and thyroid function and the relationship between thyroid function and subsequent neurodevelopment.

METHODS

A population-based birth cohort of 182 children was followed annually up to 5.5 years of age. The assessments included OC concentrations in maternal pregnancy serum and milk, clinical thyroid parameters in maternal and cord serum, and subsequent neuropsychological outcomes of the child, along with sociodemographic cofactors. Resin triiodothyronine uptake ratio (T3RU) was also assessed as an estimate of the amount of thyroxine-binding globulin (TBG) sites unsaturated by thyroxine. The T3RU is high in hyperthyroidism and low in hypothyroidism.

RESULTS

The findings showed consistent inverse and monotonic associations between organochlorine exposure and T3RU after covariate adjustments. We observed no associations with other thyroid parameters. T3RU was positively associated with improved performance on most of the neuropsychological tests. For other thyroid parameters, the findings were less consistent.

CONCLUSIONS

The results suggest that OC exposures may decrease the T3RU during early life, which is a proxy measure of the binding capacity of TBG. In addition, minor decreases of the thyroid function may be inversely associated with a child's neurodevelopment.

[Clinical significance of 5-HT and DA levels in serum and cerebrospinal fluid of the patients with delayed encephalopathy after acute carbon monoxide poisoning]

OBJECTIVE

To explore the changes and the clinical significance of 5-hydroxytryptamine (5-HT), dopamine (DA) levels in serum and cerebrospinal fluid (CSF) of patients with delayed encephalopathy (DEACMP) after acute carbon monoxide poisoning.

METHODS

The dynamic detection of 5-HT and DA levels in serum and CSF from 42 patients with DEACMP was performed with high performance liquid chromatography (HPLC). The condition changes of patients with DEACMP were analyzed with three types of scales: the activity of daily living scale (ADL), information memory concentration test (IMCT) and Hasegawa's dementia scale (HDS); these changes were compared with those from 38 other encephalopathy patients and 38 non-encephalopathy patients, respectively.

RESULTS

Before treatment, the serum 5-HT and DA levels [(662.61 ± 178.50) and (155.74 ± 60.32) nmol/L, respectively] of DEACMP group were both significantly lower than those [(914.08 ± 198.04) and (225.70 ± 48.53) nmol/L] of non-encephalopathy group (P < 0.05); the serum DA level of DEACMP group was also significantly lower than that [(243.57 ± 66.94) nmol/L] of other encephalopathy group (P < 0.05); the serum 5-HT level of DEACMP group was not significantly different from that [(729.54 ± 299.87) nmol/L] of other encephalopathy group (P > 0.05). After treatment, the serum 5-HT and DA levels [(714.08 ± 170.47) and (192.18 ± 33.07 nmol/L, respectively)] of DEACMP group elevated to various extent, but only serum DA level was significantly higher than that before treatment (P < 0.05). Before treatment, the CSF 5-HT and DA levels of DEACMP group were significantly lower than those of non-encephalopathy group and those of other encephalopathy group (P < 0.05). After treatment, the CSF 5-HT level (232.44 ± 54.28 nmol/L) was similar to normal level and significantly higher than that before treatment (P < 0.05); the CSF DA level [(56.83 ± 12.85) nmol/L] of DEACMP group increased only slightly (P > 0.05). In DEACMP group, ADL score (50.64 ± 7.23), HDS score (8.55 ± 8.08) and IMCT score (4.95 ± 7.30) before treatment were significantly different from those (8.5 ± 8.08, 4.95 ± 7.30 and 15.64 ± 10.90) after treatment (P < 0.01). In DEACMP group, there wasa negative correlation between DA level changes and HDS score changes, when the DA levels and HDS scores before treatment were compared with those after treatment (P < 0.05).

CONCLUSION

The dynamic changes of 5-HT and DA levels in serum and CSF of patients with DEACMP consisted basically with the patient's condition change. The dynamically detected 5-HT and DA levels can be used as the biological indicators to reflect the condition change and treatment effects of DEACMP patients.

Fatal cerebral edema associated with serine deficiency in CSF

Two young girls without a notable medical history except for asthma presented with an acute toxic encephalopathy with very low serine concentrations both in plasma and cerebrospinal fluid (CSF) comparable to patients with 3-phosphoglycerate dehydrogenase (3-PGDH) deficiency. Clinical symptoms and enzyme measurement (in one patient) excluded 3-PGDH deficiency. Deficiencies in other serine biosynthesis enzymes were highly unlikely on clinical grounds. On basis of the fasting state, ketone bodies and lactate in plasma, urine and CSF, we speculate that reduced serine levels were due to its use as gluconeogenic substrate, conversion to pyruvate by brain serine racemase or decreased L-serine production because of a lack of glucose. These are the first strikingly similar cases of patients with a clear secondary serine deficiency associated with a toxic encephalopathy.

Neurotoxic effects and biomarkers of lead exposure: a review

Lead, a systemic toxicant affecting virtually every organ system, primarily affects the central nervous system, particularly the developing brain. Consequently, children are at a greater risk than adults of suffering from the neurotoxic effects of lead. To date, no safe lead-exposure threshold has been identified. The ability of lead to pass through the blood-brain barrier is due in large part to its ability to substitute for calcium ions. Within the brain, lead-induced damage in the prefrontal cerebral cortex, hippocampus, and cerebellum can lead to a variety of neurologic disorders. At the molecular level, lead interferes with the regulatory action of calcium on cell functions and disrupts many intracellular biological activities. Experimental studies have also shown that lead exposure may have genotoxic effects, especially in the brain, bone marrow, liver, and lung cells. Knowledge of the neurotoxicology of lead has advanced in recent decades due to new information on its toxic mechanisms and cellular specificity. This paper presents an overview, updated to January 2009, of the neurotoxic effects of lead with regard to children, adults, and experimental animals at both cellular and molecular levels, and discusses the biomarkers of lead exposure that are useful for risk assessment in the field of environmental health.

Early neurotoxic effects of inhalation exposure to aluminum and/or manganese assessed by serum levels of phospholipid-binding Clara cells protein

Little is known on the disturbances of lung epithelium function in aluminum casting smelters and shipyard welders exposed by inhalation to irritant occupational pollutants, dust and fumes. The exact mechanism of aluminum and manganese toxicity is not known, but it is thought that they may potentiate oxidative and inflammatory stress, leading to impaired neurological function. The aim of the study was to investigate the subclinical effects of aluminum and manganese exposure on the nervous system and to assess their relationship to the biomarkers of exposure and effect in workers exposed to neurotoxic fumes. The relationship between the neurological and respiratory effects was investigated in 50 workers at aluminum casting smelters exposed to x(GM) = 0.29 Al(2)O(3) mg m(-3), and 59 shipyard welders exposed to x(GM) = 0.16 Mn mg m(-3), and the reference group. Serum anti-inflammatory, phospholipid-binding Clara cell protein (CC16) as a peripheral marker of the bronchiolar epithelium function measured. The lowest CC16 concentrations were found in workers showing subjective CNS symptoms and abnormal neurophysiological findings: EEG and visual evoked potentials. A strong inverse relationship was found between serum Al (Al-S) and CC16 concentrations (p = 0.006). Younger smelter workers and welders, with a shorter exposure duration, presented a higher number of VEPs than the workers employed for a longer period of time. The sub-clinical neurological symptoms (VEP) and low CC16 level can be associated with an internalization of Al ions with lipid fractions of the lung epithelium, which in turn may help Al ions overcome the blood-brain barrier. The inhibited secretion of anti-inflammatory Clara cell protein and low respiratory performance in younger Mn welders was found to enhance subclinical neurotoxic symptoms, especially VEPs, related to exposure to airborne Mn and Mn-B.

An HPLC method for the simultaneous determination of neurotoxic dipyridyl isomers in human plasma

Several studies on dipyridyl isomers have suggested that they are neurotoxic and that chronic exposure to these compounds could be a potential human health hazard. A reversed phase HPLC method was developed for the simultaneous quantitation of 2,2'-dipyridyl and its four positional isomers, 2,3'-, 2,4'-, 3,4'- and 4,4'-dipyridyl in human plasma. Plasma samples were basified, extracted with 1-chlorobutane, evaporated, the residue reconstituted in mobile phase, and an aliquot part was analyzed by HPLC. Chromatographic separations were performed on a C(18) reversed phase Sunfire column eluted with a mobile phase composed of potassium phosphate (pH 3.5; 25 mM)-acetonitrile (80:20, v/v). Isomers were separated with good resolution, and quantification was determined utilizing an internal standard of quinoxaline. The method has been validated over a range from 30 to 2000 ng/ml with correlation coefficients higher than 0.995. Extraction recoveries for the dipyridyl isomers averaged from 65 to 92%. Limit of detection and limit of quantitation for the dipyridyl isomers ranged from 15 to 70 ng/ml and 30 to 90 ng/ml, respectively. The inter- and intra-day variation did not exceed 7% with an accuracy range of 96-102%. The described analytical method was successfully utilized for the determination of dipyridyl isomers in human plasma and suggested the need for more routine monitoring of tobacco smokers and other individuals who are involuntarily exposed to environmental source of dipyridyl isomers.

D-Lactic acid-induced neurotoxicity in a calf model

Lactic acidosis (DAC) occurs as a complication of short-bowel syndrome in humans and in a variety of other gastrointestinal disorders in monogastrics and ruminants. DAC is associated with signs of impaired central nervous system (CNS) function including ataxia and coma. The objective of this experiment was to determine whether either acidification of nervous tissue or d-lactic acid is responsible for decreased neurological function. Eight Holstein calves (32 +/- 11 days, 70 +/- 10 kg) were surgically catheterized with indwelling intravenous jugular and atlanto-occipital space cerebrospinal fluid (CSF) catheters and infused for 6 h in random order with isomolar dl-lactic acid (dl-LA), l-lactic acid (l-LA), hydrochloric acid (HCl), or saline. dl-LA induced ataxia after 4 h of infusion and produced the greatest obtunding of CNS function (at 7 h, score 8.0 +/- 0.4), whereas the other infusions caused neither ataxia nor scores over 1.5 (P < 0.01 from dl-LA). dl-LA induced significantly less acidemia than HCl (at 6 h pH 7.13 +/- 0.06 and 7.00 +/- 0.04, base excess -16 +/- 1 and -23 +/- 3 mmol/l, bicarbonate 11 +/- 1 and 8 +/- 1 mmol/l respectively, all P < 0.01) but greater than l-LA and saline (P < 0.01). CSF changes followed a similar but less pronounced pattern. Although HCl infusion produced a severe acidemia and CSF acidosis, only minor effects on neurological function were evident suggesting that d-lactate has a direct neurotoxic effect that is independent of acidosis. Conversely, l-LA produced only minor neurological changes.

Biosensor assay of neuropathy target esterase in whole blood as a new approach to OPIDN risk assessment: review of progress

Organophosphates (OPs) that inhibit neuropathy target esterase (NTE) with subsequent ageing can produce OP-induced delayed neuropathy (OPIDN). NTE inhibition in lymphocytes can be used as a biomarker of exposure to neuropathic OPs. An electrochemical method was developed to assay NTE in whole blood. The high sensitivity of the tyrosinase carbon-paste biosensors for the phenol produced by hydrolysis of the substrate, phenyl valerate, allowed NTE activity to be measured in diluted samples of whole blood, which cannot be done using the standard colorimetric assay. The biosensor was used to establish correlations of NTE inhibitions in blood with that in lymphocytes and brain after dosing hens with a neuropathic OP. The results of further studies demonstrated that whole blood NTE is a reliable biomarker of neuropathic OPs for up to 96 hours after exposure. These validation results suggest that the biosensor NTE assay for whole blood could be developed to measure human exposure to neuropathic OPs as a predictor of OPIDN. The small blood volume required (100 microL), simplicity of sample preparation and rapid analysis times indicate that the biosensor should be useful in biomonitoring and epidemiological studies. The present paper is an overview of our previous and ongoing work in this area.

Neuropsychological exploration of alleged mold neurotoxicity

Cognitive and emotional correlates of toxic mold exposure and potential dose-response effects for both outcomes were investigated. Self-reported length of exposure, time since last exposure, and serum immunoglobulin (IgG) levels were assessed. Despite CNS complaints often seen with mold exposed individuals, overall results did not uncover concomitant cognitive deficits suggested in previous studies or a significant reduction in intellectual functioning. Fewer subjects were excluded as result of failing effort/motivation assessment than expected. Correlations of IgG and cognitive function are discussed. A dose-effect for self-reported length of exposure and cognitive outcome was not seen. The sample's overall Minnesota Multiphasic Personality Inventory II (MMPI-2) profile indicated elevations on scales 1, 2, 3, 7 and 8. MMPI-2 clinical scales 1 and 3 were significantly correlated with length of exposure. The MMPI-2 may be sensitive to increasing physical and emotional sequelae as length of exposure increases. A potential subgroup of cognitively impaired outliers within mold exposure litigants is explored. Limitations of self-reported and objective measurements for mold exposure and exploratory statistical methodology are discussed.

Malondialdehyde and catalase as the serum biomarkers of allyl chloride-induced toxic neuropathy

Chronic exposure to allyl chloride (AC) is known to produce a central-peripheral distal axonopathy. To access the biomarker of exposure and elucidate the mechanism of neuropathy induced by AC, we performed a longitudinal observational study of malondialdehyde (MDA), anti-reactive oxygen species (anti-ROS), glutathione (GSH), catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD) in rats serum and sciatic nerve after 0, 3, 6, 9 and 12 weeks of AC administration. AC was administrated to Wistar rats by gavage at a single dosage of 200 mg/kg/per dose (three times per week). Rats were sacrificed after 0, 3, 6, 9 and 12 weeks of AC treatment, serum and sciatic nerves were quickly collected at 4 degrees C. The results showed that MDA levels in serum (115.4 and 126.2%) and sciatic nerve (130.5 and 145.3%) significantly increased (p<0.05) on 3rd week of AC treatment and at gait score of 2, and further changes of MDA levels were observed after 6, 9 and 12 weeks and at gait score of 3 and 4. While a decrease (p<0.05) in the activities of CAT on 6th week of AC intoxication and at gait score of 2 was observed in serum (81.2 and 72.8%) and sciatic nerve (71.7 and 70.7%). The other antioxidants also decreased in serum and sciatic nerve after 3, 6 and 9, 12 weeks' intoxication and at gait score of 2, 3 and 4. Significant (p<0.05) positive correlations were observed between serum and sciatic nerve in MDA levels (r=0.9162 and 0.9551, respectively) and CAT (r=0.9410 and 0.9557, respectively) activities as time went on and symptoms developed. Thus, AC intoxication was associated with elevation of lipid peroxidation and reduction of antioxidative status, and the time dependent changes of these indexes in Wistar rats' serum and sciatic nerve occurred. The misbalance of lipid peroxidation and antioxidation status might be one of mechanisms of toxic neuropathy induced by AC. MDA and CAT could be served as the biomarkers of AC exposure to afford the early diagnosis of AC-induced toxic neuropathy.

Monitoring for Adverse Effects of Antiepileptic Drugs

Best practices for monitoring the adverse effects of antiepileptic drugs (AEDs) have not been carefully studied. Routine blood and urine studies do not appear to be of value in asymptomatic patients to avoid severe acute reactions. Subtle chronic AED side effects exist but algorithms for their detection and treatment are not well developed. Randomized clinical trials do not support the value of routine AED serum levels to improve compliance, seizure control, or avoid side effects. Simple screening procedures for neurotoxicity have not been developed. Some personal suggestions are offered.

Blood protein reactions to ablation of capsaicin-sensitive neurons

The effects of ablation of afferent neurons with neurotoxic doses of capsaicin (150 mg/kg) on protein levels in plasma fractions were studied by polyacrylamide gel electrophoresis in Wistar rats at different times points after administration of capsaicin and in inflammatory reactions induced by zymosan (10 mg/100 g). Administration of neurotoxic doses of capsaicin induced biphasic changes in protein levels in plasma fractions. During the initial period (up to seven days), "acute-type" changes in protein content were seen; at 11-30 days, there were chronic increases in the albumin level with decreases in alpha(1), alpha(2), and gamma globulins. Defunctionalization of capsaicin-sensitive nerves 14-30 days before induction of inflammation prevented the "acute-phase" changes in protein contents in the albumin, alpha(1), alpha(2), and beta globulin fractions in response to induction of inflammation with zymosan.

High signal intensity on magnetic resonance imaging as a predictor of neurobehavioral performance of workers exposed to manganese

INTRODUCTION

Using previously obtained cross-sectional data from a nationwide survey on workers exposed to manganese (Mn), we assessed the relation of high signal intensity with neurobehavioral effects, and reevaluated the preexisting cross-sectional data to get additional findings on the relation of high signals with other Mn-exposure indices.

SUBJECTS AND METHODS

Subjects were the same as those in the previous study. The exposure status was reassessed based on similar exposure groups. The signal intensity of the globus pallidus (GP) relative to frontal white matter was subjectively evaluated as either with or without increased signals, and the increased signals were further graded into three categories. For quantitative evaluation of signal intensities of the GP we also calculated the pallidal index (PI). Neurobehavioral function was assessed using the World Health Organization Neurobehavioral Core Test Battery. In addition, computerized finger tapping speed was included to assess motor speed.

RESULTS

The mean blood Mn for those with grade III was significantly greater than those without increased signals and those with grade I. Airborne Mn and PI also showed similar findings. PI paralleled subjective MRI gradings. The proportion of workers with increased signals increased with all the Mn-exposure variables, airborne and blood Mn, the duration of work, and cumulative exposure. The PI was significantly associated with a correct score of pursuit aiming II tests and finger tapping of the dominant hand after control of age and educational level among neurobehavioral performances.

DISCUSSION

The present findings showed that signal index on T1-weighted MRI showed a dose-response relationship with all the Mn-exposure variables. The two neurobehavioral tests reflecting fine motor function were significantly decreased above 107.1 of PI, the cutoff point between those with and without increased signals. Hence, signal intensity on MRI is an effective predictor of the neurobehavioral performance of Mn exposed workers.

[On laboratory diagnostics of early alcoholism and comorbid visceropathy]

The article is dedicated to methodical approaches to revealing organopathological consequences of alcohol abuse in adolescents. The author describes laboratory criteria of pre-nosological disturbances in homeostasis which characterize functional changes in the somatic sphere and adaptation. Algorithms of biochemical diagnostics of internal diseases accompanying alcohol abuse are presented.

Ontogeny of hepatic and plasma metabolism of deltamethrin in vitro: role in age-dependent acute neurotoxicity

Deltamethrin (DLM) is a relatively potent and widely used pyrethroid insecticide. Inefficient detoxification has been proposed to be the primary reason for the greater sensitivity of immature rats to the acute neurotoxicity of DLM. The objective of this study was to test this hypothesis by characterizing the age dependence of DLM metabolism in vitro, as well as toxic signs and blood levels of the neurotoxic parent compound following administration of 10 mg DLM/kg p.o. in glycerol formal. Metabolism was quantified in vitro by monitoring the disappearance of the parent compound from plasma [via carboxylesterases (CaEs)] and liver microsomes [via CaEs and cytochromes P450 (P450s)] obtained from 10-, 21-, and 40-day-old male Sprague-Dawley rats. Mean (+/-S.E.) intrinsic clearances (Vmax/Km) in these respective age groups by liver P450s (4.99+/-0.32, 16.99+/-1.85, and 38.45+/-7.03) and by liver CaEs (0.34+/-0.05, 1.77+/-0.38, and 2.53+/-0.19) and plasma CaEs (0.39+/-0.06, 0.80+/-0.09, and 2.28+/-0.56) increased significantly (p<or=0.05) with age, because of progressive increases in Vmax. Intrinsic clearance of DLM by plasma CaEs and liver P450s reached adult levels by 40 days, but clearance by liver CaEs did not. Hepatic P450s played the predominant role in DLM biotransformation in young and adult rats. The incidence and severity of neurotoxic effects varied inversely with age. Correspondingly, blood DLM areas under the concentration versus time curve (AUCs) and Cmax values progressively decreased with increasing age. Internal exposure to DLM (blood AUCs) was closely correlated with toxic signs (salivation and tremors). The present study provides evidence that the limited metabolic capacity of immature rats contributes to elevated systemic exposure and ensuing neurotoxic effects of DLM.

[Laboratory changes in exo- and endotoxemia in toxicohypoxic encephalopathy occurring with acute poisoning by psychopharmacological agents]

Examinations of patients with acute oral poisoning by psychotropic agents have indicated that toxicohypoxic encephalopathy develops, when the high concentrations of toxicants and their active metabolites specifically affect brain structures, resulting in oxidative stress and impaired natural detoxification mechanisms.

Biochemical markers of neurotoxicity in wildlife and human populations: considerations for method development

Disruption of neurochemical parameters in blood and brain tissues can be used as early biomarkers of neurotoxicity in human and wildlife epidemiological studies. To investigate the feasibility of biomarker measurements in field samples obtained from remote locations, tissue storage limits were determined with human blood and mink cortex tissue using efficient and cost-effective microplate assays. Results show that isolated blood platelets and plasma can be stored at 4 degrees C for 4 wk before measurement of monoamine oxidase (MAO) and cholinesterase (ChE) activities, while human lymphocytes can be stored at 4 degrees C for up to 2 d before muscarinic acetylcholine (mACh) receptor binding analysis. Blood cells stored frozen resulted in decreased MAO activity and mACh receptor function. These data suggest that mink brain tissue obtained from field samples can be stored at various temperatures without affecting dopamine (D2) and mACh receptor densities; however, MAO and ChE activities were most stable in samples stored in a -20 degrees C domestic freezer or at 4 degrees C. Multiple freeze/thaw cycles alter mACh and D2 receptors and MAO activity in mink cortex samples and should therefore be minimized. In conclusion, these neurochemical biomarkers can efficiently be measured in large human and wildlife neurotoxicity studies, provided proper storage conditions are maintained.

Umbilical cord mercury concentration as biomarker of prenatal exposure to methylmercury

Biomarkers are often applied to assess prenatal exposure to methylmercury in research and surveillance. In a prospective study in the Faroe Islands, the main exposure biomarkers were the mercury concentrations in cord blood and maternal hair obtained at parturition. We have now supplemented these exposure biomarkers with mercury analyses of umbilical cord tissue from 447 births. In particular, when expressed in relation to the dry weight of the tissue, the cord mercury concentration correlated very well with that in cord blood. Structural equation model analysis showed that these two biomarkers have average total imprecision of about 30%, which is much higher than the laboratory error. The imprecision of the dry-weight-based concentration was lower than that of the wet-weight-based parameter, and it was intermediate between those of the cord blood and the hair biomarkers. In agreement with this finding, regression analyses showed that the dry-weight cord mercury concentration was almost as good a predictor of methylmercury-associated neuropsychologic deficits at 7 years of age as was the cord-blood mercury concentration. Cord mercury analysis can therefore be used as a valid measure of prenatal methylmercury exposure, but appropriate adjustment for the imprecision should be considered.

Neuro-reproductive toxicities of 1-bromopropane and 2-bromopropane

2-Bromopropane was used as an alternative to chlorofluorocarbons in a Korean electronics factory and caused reproductive and hematopoietic disorders in male and female workers. This causality was revealed by animal studies, and target cells were identified in subsequent studies. After identification of 2-bromopropane toxicity, 1-bromopropane was introduced to the workplace as a new alternative to ozone-depleting solvents. 1-Bromopropane was considered less mutagenic than 2-bromopropane, but, in contrast, animal experiments revealed that 1-bromopropane is a potent neurotoxic compound compared with 2-bromopropane. It was also revealed that 1-bromopropane has reproductive toxicity, but the target cells are different from those of 2-bromopropane. Exposure to 1-bromopropane inhibits spermiation in male rats and disrupts the development of follicles in female rats, in contrast to 2-bromopropane, which targets spermatogonia and oocytes in primordial follicles. After the first animal study describing the neurotoxicity of 1-bromopropane, human cases were reported. Those cases showed decreased sensation of vibration and perception, paresthesia in the lower extremities, decreased sensation in the ventral aspects of the thighs and gluteal regions, stumbling and headache, as well as mucosal irritation, as the initial symptoms. The dose-response of bromopropanes in humans and mechanism(s) underlying the differences in the toxic effects of the two bromopropanes remain to be determined.

High serum concentrations of the acyclovir main metabolite 9-carboxymethoxymethylguanine in renal failure patients with acyclovir-related neuropsychiatric side effects: an observational study

BACKGROUND

Acyclovir (ACV) has been used for over two decades to treat herpes virus infections. Serious neurological adverse side effects have occurred during ACV treatment in patients with renal failure, but the cause of the symptoms remains unknown. We hypothesized that increased concentrations of the ACV main metabolite 9-carboxymethoxymethylguanine (CMMG) correlated to these symptoms.

METHODS

We conducted an observational study from 1991 to mid 1999 based on samples sent for analysis of ACV concentration from various hospital departments in Sweden. Patients with neuropsychiatric symptoms (NS+, n=49) were compared with patients without symptoms (NS-, n=44). ACV and CMMG concentrations were analysed by HPLC. Medical records were analysed for symptoms and compared with pertinent cases identified from Medline.

RESULTS

The serum CMMG levels were significantly higher in the NS+ group (mean=34.1 micro mol/l, 95% confidence interval 23.4-46.1) compared with the NS- group (mean=4.7 micro mol/l, 95% confidence interval 3.3-6.6; P<0.001). CMMG was the strongest predictor in a receiver-operating characteristics curve analysis (ROC), based on 77 patients, of ACV-related neuropsychiatric symptoms. The ROC curve for CMMG demonstrated that neuropsychiatric symptoms could be predicted with a sensitivity of 91% and a specificity of 93% with the use of a cut-off value of 10.8 micro mol/l of CMMG. Thirty-five of 49 patients in the NS+ group showed levels exceeding this concentration compared with only three of 44 of patients in the NS- group (P<0.001). ACV exposure, ACV concentration, creatinine clearance and creatinine concentration were weaker but statistically significant predictors. Haemodialysis reduced CMMG and ACV levels and relieved the symptoms.

CONCLUSIONS

The determination of CMMG levels in serum may be a useful tool in supporting the diagnosis of ACV-associated neuropsychiatric symptoms. Furthermore, the monitoring of CMMG levels may prevent the emergence of symptoms.