Susceptibility to seizure-induced injury and acquired microencephaly following intraventricular injection of saporin-conjugated 192 IgG in developing rat brain

To study the role of neurotrophin-responsive neurons in brain growth and developmental resistance to seizure-induced injury, we infused saporin-conjugated 192-IgG (192 IgG-saporin), a monoclonal antibody directed at the P75 neurotrophin receptors (p75(NTR)), into the ventricles of postnatal day 8 (P8) rat pups. 7-10 days after immunotoxin treatment, loss of p75(NTR) immunoreactivity was associated with depletion of basal forebrain cholinergic projection to the neocortex and hippocampus. Kainic acid (KA)-induced seizures on P15 resulted in hippocampal neuronal injury in the majority of toxin-treated animals (13/16), but only rarely in saline-injected controls (2/25) (P < 0.001). In addition, widespread cerebral atrophy and a significant decrease in brain weight with preserved body weight were observed. Volumetric analysis of the hippocampal hilar region revealed a 2-fold reduction in perikaryal size and a 1.7-fold increase in cell packing density after 192 IgG-saporin injection. These observations indicate that neurotrophin-responsive neurons including basal forebrain magnocellular cholinergic neurons may be critical for normal brain growth and play a protective role in preventing excitotoxic neuronal injury during development.

Education for men with solvent-induced chronic toxic encephalopathy and their spouses

In this study an education, and a series of group sessions for patients with solvent-induced chronic toxic encephalopathy (TE) and their spouses are evaluated. Thirty-eight patients and 21 family members participated in a 1-day education scheduled with short lectures on the clinical examination of chronic toxic encephalopathy and the prognosis. A specialist in occupational medicine, a psychologist and a social worker gave the lectures. Small discussion groups were also arranged. Of the participants from the educational days, 16 TE patients and 14 wives attended a 10-week counselling and coping improvement program with separate group sessions once a week, for patients and spouses. Questionnaires were used to assess symptoms, social network, mastery and family climate, and the participants' satisfaction with the education and the group sessions. The majority of the participants experienced the 1-day information as useful and relevant. The 10-week group sessions were rated as meaningful and the design, number, duration and frequency of the sessions equally good. Self-reported symptoms, social network and mastery were measured before the group sessions, and 3 and 9 months after breaking up the group sessions. In most measurements, there were no statistically significant differences between the three points in time. However, the wives improved more than did the patients but the effect was not lasting the whole follow-up period. Considering the patients' dependence on their wives, it might be most important that the wives experienced some relief from their own symptoms.

Critical periods for the role of oxidative stress in the developmental neurotoxicity of chlorpyrifos and terbutaline, alone or in combination

The developmental neurotoxicity of chlorpyrifos (CPF) involves mechanisms other than inhibition of cholinesterase. In the current study, we examined the ability of CPF to evoke lipid peroxidation in the developing brain of fetal and neonatal rats. CPF given to pregnant rats on gestational days 17-20 or to neonatal rats on postnatal days 1-4, failed to elicit increases in thiobarbituric acid-reactive species (TBARS) in brain regions even when the dose was raised above the threshold for systemic toxicity and hepatic damage. In contrast, CPF administration during the second postnatal week, the peak period of neuronal cell differentiation and synaptogenesis, did evoke significant increases in TBARS even at a dose devoid of systemic toxicity. Terbutaline, which is chemically unrelated to CPF and which stimulates neuronal cell metabolism through direct actions on beta-adrenoceptors, also elicited oxidative damage in the developing brain with greater sensitivity in the second postnatal week. These results indicate that diverse compounds can exert convergent effects on brain development through their shared potential to elicit oxidative stress, and that the net outcome is dependent upon specific developmental stages in which metabolic demand is especially high. Furthermore, given the common use of terbutaline in the therapy of preterm labor, and the nearly ubiquitous exposure of the human population to organophosphorus pesticides, the combined oxidative burden of exposure to both agents may contribute to the worsened neurodevelopmental outcomes noted in animal models of such dual exposures.

Chronic neuropsychological sequelae of cholinesterase inhibitors in the absence of structural brain damage: two cases of acute poisoning

Here we describe two cases of carbamate poisoning. Patients AMF and PVM were accidentally poisoned by cholinesterase inhibitors. The medical diagnosis in both cases was overcholinergic syndrome, as demonstrated by exposure to cholinesterase inhibitors. The widespread use of cholinesterase inhibitors, especially as pesticides, produces a great number of human poisoning events annually. The main known neurotoxic effect of these substances is cholinesterase inhibition, which causes cholinergic overstimulation. Once AMF and PVM had recovered from acute intoxication, they were subjected to extensive neuropsychological evaluation 3 and 12 months after the poisoning event. These assessments point to a cognitive deficit in attention, memory, perceptual, and motor domains 3 months after intoxication. One year later these sequelae remained, even though the brain magnetic resonance imaging (MRI) and computed tomography (CT) scans were interpreted as being within normal limits. We present these cases as examples of neuropsychological profiles of long-term sequelae related to acute poisoning by cholinesterase inhibitor pesticides and show the usefulness of neuropsychological assessment in detecting central nervous system dysfunction in the absence of biochemical or structural markers.

Dexamethasone prevents long-lasting learning impairment following a combination of lipopolysaccharide and hypoxia-ischemia in neonatal rats

OBJECTIVE

There are no established therapies for preventing or rescuing perinatal infection or inflammation-induced perinatal brain damage. We administered dexamethasone (DEX), a synthetic corticosteroid anti-inflammatory drug, to neonatal rats in a model of such damage induced by a combination of lipopolysaccharide (LPS) and hypoxia-ischemia (HI), which produces characteristic histologic and behavioral abnormalities.

STUDY DESIGN

Four hours after the injection of LPS (1 mg/kg, i.p.), 7-day-old Wistar rat pups were subjected to unilateral HI for 1 hour according to Levine's procedure. Injections of 0.5 mg/kg of dexamethasone (DEX-treated group, n = 15) or saline (saline-treated group, n = 15) were given 4 hours before HI. A sham-operated control group received neither LPS nor HI (n = 15). We chose rats of this age because their stage of brain maturation is similar to the human neonate. Over the 7 to 16 weeks after treatment, a choice reaction time (CRT) task was used for assessment of attention processes in each group, an 8-arm radial maze task was used to test short-term memory, and a water maze task was used to test long-term memory. In the CRT task, the reward food was released when the tested animal correctly pressed a lever on the side of an illuminating lamp. The correct and incorrect lever pressings were counted. In the 8-arm radial maze task, rats were allowed to move freely, seeking a reward of food placed at the end of 1 arm. An error was defined as the choice of an arm that had already been visited. In the water maze, rats had to swim to seek a concealed platform as aversive escape motivation. At 19 weeks, the rats were euthanized, the brain was removed, sectioned coronally, and the volume of each part was measured.

RESULTS

The striatum, cortex, and hippocampus showed reductions in volume in the saline-treated group (42.7%, 49.2%, and 34.9% decreases compared with the sham-operated controls, respectively), but this was not observed in the DEX-treated group. All learning and memory processes were impaired with the combination of LPS and HI treatment, but these deficits were almost completely prevented by DEX treatment.

CONCLUSION

Dexamethasone is a promising candidate for prevention of infection and inflammation-induced perinatal brain damage. The impact of dexamethasone identifies potential therapeutic pathways once the mechanism of dexamethasone's protection is determined.

Egocentric Disorientation following Bilateral Parietal Lobe Damage

Aguirre and D'Esposito (1999) suggested a taxonomy and theoretical framework for understanding topographical disorders. One of the problems they described involved egocentric disorientation, in which deficits are not strictly confined to the topographical sphere but are seen on a wide variety of visuo-spatial paradigms. Here, we report a neuropsychological investigation of MU, a person with egocentric disorientation. To test the usefulness of Aguirre and D'Esposito's framework, we administered tests which were predicted to be easy or difficult for people with egocentric disorientation to show that MU was impaired on tasks sensitive to egocentric disorientation and that he showed adequate performance on tests sensitive to other types of topographical representation. Thus MU showed normal performance on a test of recognition of famous landmarks and he could identify photographs of personally familiar places in his home town, yet he could not say how to get from a recognised building to another place in his environment. His performance fulfils the criteria for egocentric disorientation and fits the predictions derived from Aguirre and D'Esposito's views.

Transplanted human embryonic germ cell-derived neural stem cells replace neurons and oligodendrocytes in the forebrain of neonatal mice with excitotoxic brain damage

Stem cell therapy is a hope for the treatment of some childhood neurological disorders. We examined whether human neural stem cells (hNSCs) replace lost cells in a newborn mouse model of brain damage. Excitotoxic lesions were made in neonatal mouse forebrain with the N-methyl-D-aspartate (NMDA) receptor agonist quinolinic acid (QA). QA induced apoptosis in neocortex, hippocampus, striatum, white matter, and subventricular zone. This degeneration was associated with production of cleaved caspase-3. Cells immunopositive for inducible nitric oxide synthase were present in damaged white matter and subventricular zone. Three days after injury, mice received brain parenchymal or intraventricular injections of hNSCs derived from embryonic germ (EG) cells. Human cells were prelabeled in vitro with DiD for in vivo tracking. The locations of hNSCs within the mouse brain were determined through DiD fluorescence and immunodetection of human-specific nestin and nuclear antigen 7 days after transplantation. hNSCs survived transplantation into the lesioned mouse brain, as evidenced by human cell markers and DiD fluorescence. The cells migrated away from the injection site and were found at sites of injury within the striatum, hippocampus, thalamus, and white matter tracts and at remote locations in the brain. Subsets of grafted cells expressed neuronal and glial cell markers. hNSCs restored partially the complement of striatal neurons in brain-damaged mice. We conclude that human EG cell-derived NSCs can engraft successfully into injured newborn brain, where they can survive and disseminate into the lesioned areas, differentiate into neuronal and glial cells, and replace lost neurons. (c) 2005 Wiley-Liss, Inc.

Effects of executive impairments on maladaptive explanatory styles in substance abusers: clinical implications

Our study examined the relation between neuropsychological impairment of executive functions and explanatory styles, according to the Abramson model of learned helplessness in humans, in a sample of substance abusers. Thirty-eight polysubstance abusers were assessed during an abstinence period using a selective neuropsychological battery for the evaluation of the executive functions, as well as the Attributional Style Questionnaire (ASQ) for the assessment of the three dimensions of explanatory style: Internality-Externality, Stability-Instability and Globality-Specificity. Multiple regression analyses showed significant relationships among performance on different neuropsychological tasks sensitive to executive functions and characteristic cognitive styles. The results showed the performance on cognitive flexibility and response inhibition tasks is directly related to making more internal attributions for positive situations, and inversely related to the appearance of more stable attributions for negative events. Likewise, adequate performance on working memory tasks was related to development of more global attributions for failures. These results are partially congruent with the learned helplessness model and particularly relevant for the clinical management of substance abusers and the success on the treatment and rehabilitation of these subjects.

Acute barium nitrate intoxication treated by hemodialysis

A 22-year-old male was admitted to hospital with diarrhea and vomiting, cardiac arrhythmias, severe hypokalemia and gradual onset of muscular weakness. A potassium infusion was started, but for several hours serum potassium remained low. Evidence of toxic ingestion was initially lacking. When it became clear -- after a considerable delay -- that the patient had ingested barium nitrate, hemodialysis was started. This resulted in rapid clinical improvement with correction of hypokalemia and restored muscular function. Intoxication with barium causes hypokalemia, arrhythmias, muscular weakness and paralysis, often requiring respiratory support. This patient presented with symptoms typical of severe barium intoxication, non-responsive to potassium supplementation. There are few published reports on the use of hemodialysis in barium poisoning. This case confirms the possible benefit of hemodialysis in severe cases, where potassium supplementation alone is insufficient.

Solvent-related chronic toxic encephalopathy as a target in the worker's mental health research

The article is aimed at discussing the theoretical grounds which support the diagnosis of solvent-related chronic encephalopathy in the field of the worker's mental health, having it as a target in this area. The psychiatric, neurological and labor health postulates which contribute to the multidisciplinary description of such diagnostic category are presented.

Injuries Associated with Regional Anesthesia in the 1980s and 1990s

Background

The authors used the American Society of Anesthesiologists Closed Claims Project database to identify specific patterns of injury and legal liability associated with regional anesthesia. Because obstetrics represents a unique subset of patients, claims with neuraxial blockade were divided into obstetric and nonobstetric groups for comparison.

Methods

The American Society of Anesthesiologists Closed Claims Project is a structured evaluation of adverse anesthetic outcomes collected from closed anesthesia malpractice insurance claims of professional liability companies. An in-depth analysis of 1980-1999 regional anesthesia claims was performed with a subset comparison between obstetric and nonobstetric neuraxial anesthesia claims.

Results

Of the total 1,005 regional anesthesia claims, neuraxial blockade was used in 368 obstetric claims and 453 of 637 nonobstetric claims (71%). Damaging events in 51% of obstetric and 41% of nonobstetric neuraxial anesthesia claims were block related. Obstetrics had a higher proportion of neuraxial anesthesia claims with temporary and low-severity injuries (71%) compared with the nonobstetric group (38%; P &lt;or=0.01) and a lower proportion of claims with death or brain damage and permanent nerve injury compared with the nonobstetric group (P &lt;or= 0.01). Cardiac arrest associated with neuraxial block was the primary damaging event in 32% of obstetric and 38% of nonobstetric neuraxial anesthesia claims involving death or brain damage. Eye blocks accounted for 5% of regional anesthesia claims.

Conclusion

Obstetric claims were predominately associated with minor injuries. Permanent injury from eye blocks increased in the 1990s. Neuraxial cardiac arrest and neuraxial hematomas associated with coagulopathy remain sources of high-severity injury.

Long-term behavioral and morphological consequences of nonconvulsive status epilepticus in rats

The aims of the present study were to ascertain whether nonconvulsive status epilepticus (NCSE) could give rise to long-term behavioral deficits and permanent brain damage. Two months after NCSE was elicited with pilocarpine (15 mg/kg i.p.) in LiCl-pretreated adult male rats, animals were assigned to either behavioral (spontaneous behavior, social interaction, elevated plus-maze, rotorod, and bar-holding tests) or EEG studies. Another group of animals was sacrificed and their brains were processed for Nissl and Timm staining as well as for parvalbumin and calbindin immunohistochemistry. Behavioral analysis revealed motor deficits (shorter latencies to fall from rotorod as well as from bar) and disturbances in the social behavior of experimental animals (decreased interest in juvenile conspecific). EEGs showed no apparent abnormalities. Quantification of immunohistochemically stained sections revealed decreased amounts of parvalbumin- and calbindin-immunoreactive neurons in the motor cortex and of parvalbumin-positive neurons in the dentate gyrus. Despite relatively inconspicuous manifestations, NCSE may represent a risk for long-term deficits.

Brain but not lung functions impaired after a chlorine incident

A workplace bleach exposure incident was studied in 13 women to determine whether chlorine caused neurobehavioral and pulmonary functional effects. We compared neurophysiological and neuropsychological measurements in 13 chlorine-exposed women, 4.5 years after exposure, and 41 unexposed women. Reaction times, balance, blink reflex latency, color discrimination and several psychological tests were measured. Pulmonary function was assessed by spirometry. A profile of mood states and frequencies of 35 symptoms were obtained. Chlorine exposed women performed statistically significantly below unexposed women for simple and choice reaction times, balance with eyes open and eyes closed, color discrimination, grip strength, Culture Fair, digit symbol substitution, vocabulary, trail making B and pegboard. Profile of mood states scores and frequency symptoms were elevated. Respiratory symptoms were elevated but pulmonary volumes and flows were not reduced. Chlorine bleach exposure was associated with impaired neurobehavioral functions and elevated POMS scores and symptom frequencies. Alternatives to chlorine should be used.

A new model for prenatal brain damage. I. GABAA receptor activation induces cell death in developing rat hippocampus

Premature infants are at exceptionally high risk for hypoxic-ischemic insults and other traumatic events that result in permanent brain damage. However, no current models adequately mimic these events. An emerging concept is that the major excitatory drive in immature neurons is derived from depolarizing responses following activation of the gamma-aminobutyric acid (GABA)(A) receptor, resulting in the opening of voltage-sensitive calcium channels. While calcium-mediated signal transduction is trophic in developing neurons, excessive calcium entry is a major mediator of excitotoxicity. We report that exogenous activation of GABA(A) receptors by muscimol in newborn rats increases cell death in the hippocampus. The effects are region specific, persistent, and greater in males. Muscimol-induced damage is prevented by pretreatment with diltiazem, an L-type voltage-sensitive calcium channel blocker. Results using hippocampal cultures parallel those observed in vivo, indicating that the effects are mediated directly in the hippocampus. Existing models of pediatric hypoxic-ischemic brain damage focus on the effects of glutamate in the postnatal day 7 rat, because it is considered analogous to the newborn human. This makes the newborn rat analogous to the late gestational human. Ischemia in newborn rats induces GABA release and we propose that treatment with muscimol mimics the cell death cascade induced by hypoxia-ischemia in premature human infants.

A novel model for prenatal brain damage. II. Long-term deficits in hippocampal cell number and hippocampal-dependent behavior following neonatal GABAA receptor activation

Premature infants are at especially high risk for asphyxia, seizures, and other conditions that cause hypoxia-ischemia. These events result in abnormal brain pathology and behavioral deficits that persist throughout adolescence and into adulthood. Current rodent models of human infant hypoxic-ischemic brain damage have focused on exogenous glutamate receptor agonist exposure in the postnatal day 7 rat. While this model is considered analogous to the newborn human, no adequate models for preterm infant brain damage have been developed. Recent work from our lab has proposed a potential model for preterm infant brain damage in which neonatal rats are treated with exogenous muscimol, the selective gamma-aminobutyric acid(A) (GABA(A)) receptor agonist, on postnatal days 0 and 1. In the companion paper to this one (Exp. Neurol., in press), we report fewer neurons in the hippocampal formation on postnatal day 7 (6 days after treatment), but the persistence of these anatomical deficits, and potential resultant behavioral dysfunctions, were not investigated. In the current experiment, we documented that muscimol exposure on postnatal days 0 and 1 leads to fewer neurons in the male and female rat hippocampus (CA1, CA2/3, and dentate gyrus) on postnatal day 21. Also, neonatal muscimol exposed males and females displayed deficits on hippocampal-dependent learning tasks such as a preweanling version of the Morris water maze task and the open field task. We conclude that exposure to exogenous GABA(A) receptor activation over the first 2 days of postnatal life, a model for preterm infant hypoxic injury, produces anatomical and behavioral deficits observed into adolescence.

Neuropsychological sequelae of chronic recreational gasoline inhalation

Brief summary test profiles are described for two cases of long-term inhalation recreationally of gasoline.

Cerebellar atrophy as a delayed manifestation of chronic carbon disulfide poisoning

A 70-year-old man developed a slowly progressive cerebellar syndrome after having been exposed to carbon disulfide (CS2) in a viscose rayon plant for 27 years. Ataxia, dysmetria, dysarthria and adiadochokinesia appeared 7 years after retirement from work (at age 54), and were later accompanied by cognitive deterioration, dysmnesia, spatio-temporal disorientation, emotional lability, and paranoid-obsessive disturbances. Brain computed tomography (CT) and magnetic resonance imaging (MRI) showed advanced global cerebellar atrophy, and a picture of less severe cerebrocortical atrophy. The case illustrates the possibility of chronic toxic encephalopathy among patients with previous long-term exposure to CS2. In such instances, cerebellar damage may develop as an exceptional, delayed manifestation of neurotoxicity: brain imaging techniques can significantly contribute to the diagnosis and follow-up, in addition to occupational anamnesis and neuropsychiatric evaluation. The patient presented also serves as a remainder that neurodegenerative disorders of apparently unknown origin sometimes derive from occupational toxic exposures suffered in the past. The clinical manifestations may appear several years after retirement from work, when the effects of toxic damage combine with age-related neuronal loss to overcome the brain functional reserve.

The brain matrix and multifocal brain damage following a single injection of ketamine in young adult rats: conspicuous changes in old age

Male rats were seized with lithium and pilocarpine and then injected within 30 min. with either acepromazine or ketamine. These rats as well as age-matched normal rats were observed daily for one year. The rats which had received the ketamine after the seizures were significantly heavier than either the normal rats or the other group of seized rats. The bulk of this increased weight was due to the marked increase in white, extremely dense adipose tissue. Compared to the acepromazine-treated rats, the ketamine-treated rats did not exhibit spontaneous seizures and exhibited cerebral widths comparable to normal rats. These results suggest that the multifocal, graded neuronal loss associated with this seizure model may allow other "configurations" to emerge that can support normal behaviors as well as new characteristics.

Butane abuse associated Encephalopathy

Butane contained in household products is easily available for abuse and is not subject to legal prosecution in Germany. The toxicological properties of butane mainly affect the heart and the CNS. A serious pathophysiological mechanism is asphyxia due to the replacement of oxygen by butane. We report an abusive butane inhalation in a 15-year old girl, resulting in cardiopulmonary resuscitation and subsequent development of severe brain damage. After reviewing the medical literature and questioning German toxicological information centres it became obvious, that abuse of butane is an increasing problem. We give an survey about the complications associated with butane intoxication.

The neuropsychiatry of carbon monoxide poisoning in attempted suicide: a prospective controlled study

OBJECTIVE

There are few prospective comprehensive controlled studies of the neuropsychiatric outcome in people who attempt suicide with carbon monoxide (CO). The present study aimed to evaluate this.

METHODS

A consecutive series of 41 adults (81% men) with CO exposure presenting over 3 years, and 20 matched controls, were evaluated with instruments to assess orientation, attention, concentration, speed of information processing, verbal memory, premorbid intellect, executive function (working memory, verbal fluency and set-switching), mood disorder, psychotic disorder, alcohol dependence and obsessive-compulsive disorder, levels of depression, hopelessness, suicide intent, anxiety, neurobehavioural function and social and interpersonal functioning. At 2 months follow-up, the neuropsychological battery was extended to include further tests of executive function (including problem-solving) and memory (including visual memory),

RESULTS

At initial assessment, control subjects showed similar levels of cognitive impairment as CO-exposed subjects (except in the case of four CO subjects with very severe impairment), but were more depressed. At 2-months follow-up, the trends were generally towards improvement in all subjects, with no between-group differences.

CONCLUSIONS

Indirect effects on cognitive state may be at least as great as direct CO neurotoxicity in suicide attempters. The study did not support CO exposure exacerbating mood disorder in this sample.

Cranial MR findings in chronic toluene abuse by inhalation

BACKGROUND AND PURPOSE

Chronic abuse of toluene by inhalation causes variable white matter changes and thalamic hypointensity on T2-weighted MR images. The purpose of our study was to assess cranial MR findings in a large series of patients who chronically abuse toluene-containing solvents to investigate the factors causing the qualitative variability of white matter changes and thalamic hypointensity.

METHODS

We studied the neurologic signs, symptoms, and cranial MR findings in 41 patients who chronically abused thinner, a toluene-containing solvent. We classified white matter changes as diffuse or restricted. We tested the associations of the development of white matter lesions and thalamic hypointensity with patient age at onset of abuse and duration of abuse.

RESULTS

MR images revealed white matter lesions in 46% of the patients, atrophic dilatation of ventricles and sulci in 27%, and thalamic hypointensity in 20%. White matter changes were restricted in 53% and diffuse in 47%. The development of white matter changes and thalamic hypointensity were significantly associated with duration of abuse longer than 4 years (P <.05 and P <.01, respectively).

CONCLUSION

White matter changes seem to start in the deep periventricular white matter, and they spread into peripheral white matter, causing the loss of gray matter-white matter differentiation with continued toluene abuse. The deposition of iron due to demyelination and axonal loss is the most probable mechanism for the thalamic hypointensity found in solvent abusers.