Safety and efficacy of tenecteplase in patients with wake-up stroke assessed by non-contrast CT (TWIST): a multicentre, open-label, randomised controlled trial

BACKGROUND

Current evidence supports the use of intravenous thrombolysis with alteplase in patients with wake-up stroke selected with MRI or perfusion imaging and is recommended in clinical guidelines. However, access to advanced imaging techniques is often scarce. We aimed to determine whether thrombolytic treatment with intravenous tenecteplase given within 4·5 h of awakening improves functional outcome in patients with ischaemic wake-up stroke selected using non-contrast CT.

METHODS

TWIST was an investigator-initiated, multicentre, open-label, randomised controlled trial with blinded endpoint assessment, conducted at 77 hospitals in ten countries. We included patients aged 18 years or older with acute ischaemic stroke symptoms upon awakening, limb weakness, a National Institutes of Health Stroke Scale (NIHSS) score of 3 or higher or aphasia, a non-contrast CT examination of the head, and the ability to receive tenecteplase within 4·5 h of awakening. Patients were randomly assigned (1:1) to either a single intravenous bolus of tenecteplase 0·25 mg per kg of bodyweight (maximum 25 mg) or control (no thrombolysis) using a central, web-based, computer-generated randomisation schedule. Trained research personnel, who conducted telephone interviews at 90 days (follow-up), were masked to treatment allocation. Clinical assessments were performed on day 1 (at baseline) and day 7 of hospital admission (or at discharge, whichever occurred first). The primary outcome was functional outcome assessed by the modified Rankin Scale (mRS) at 90 days and analysed using ordinal logistic regression in the intention-to-treat population. This trial is registered with EudraCT (2014-000096-80), ClinicalTrials.gov (NCT03181360), and ISRCTN (10601890).

FINDINGS

From June 12, 2017, to Sept 30, 2021, 578 of the required 600 patients were enrolled (288 randomly assigned to the tenecteplase group and 290 to the control group [intention-to-treat population]). The median age of participants was 73·7 years (IQR 65·9-81·1). 332 (57%) of 578 participants were male and 246 (43%) were female. Treatment with tenecteplase was not associated with better functional outcome, according to mRS score at 90 days (adjusted OR 1·18, 95% CI 0·88-1·58; p=0·27). Mortality at 90 days did not significantly differ between treatment groups (28 [10%] patients in the tenecteplase group and 23 [8%] in the control group; adjusted HR 1·29, 95% CI 0·74-2·26; p=0·37). Symptomatic intracranial haemorrhage occurred in six (2%) patients in the tenecteplase group versus three (1%) in the control group (adjusted OR 2·17, 95% CI 0·53-8·87; p=0·28), whereas any intracranial haemorrhage occurred in 33 (11%) versus 30 (10%) patients (adjusted OR 1·14, 0·67-1·94; p=0·64).

INTERPRETATION

In patients with wake-up stroke selected with non-contrast CT, treatment with tenecteplase was not associated with better functional outcome at 90 days. The number of symptomatic haemorrhages and any intracranial haemorrhages in both treatment groups was similar to findings from previous trials of wake-up stroke patients selected using advanced imaging. Current evidence does not support treatment with tenecteplase in patients selected with non-contrast CT.

FUNDING

Norwegian Clinical Research Therapy in the Specialist Health Services Programme, the Swiss Heart Foundation, the British Heart Foundation, and the Norwegian National Association for Public Health.

Health-Related Quality of Life in Pacemaker Patients: A Single and Multidimensional Self-Rated Health Comparison Study

Since implantation of the first permanent pacemaker in 1958, significant advances have been made in pacemaker technology. To date, however, health-related quality of life (HRQoL) in a large pacemaker population has not been investigated. With dwindling clinical resources, it is important to study HRQoL in a pacemaker population in a reliable and straightforward manner. This study aimed to determine and compare single and multidimensional self-rated health (SRH) in a pacemaker population in terms of sociodemographic characteristics, pacemaker mode and symptoms. The findings showed that irrespective of whether the perspective was single or multidimensional, this Swedish pacemaker population (n=697) with a mean age of 76 years had an acceptable HRQoL. Men, aged 65-84 years, persons who were cohabiting, who had their own dwelling, who had a DDD or who had a pacemaker for <or=3 and 4-7 years experienced better HRQoL. Efforts need to be made for women, single persons, the elderly and retired persons. In conclusion, the SRH of a pacemaker population can be trustworthy established by means of a single-dimensional SRH question.

Mechanical embolectomy for acute ischemic stroke in the anterior cerebral circulation: the Gothenburg experience during 2000-2011

BACKGROUND AND PURPOSE

Intra-arterial treatment of proximal occlusions in the cerebral circulation have become an important tool in the management of acute ischemic stroke. Our goal was to evaluate the safety and efficacy of intra-arterial acute ischemic stroke treatment performed in our institution in consecutive patients with anterior circulation occlusion during 2000-2011.

MATERIALS AND METHODS

We identified, in our data base, 156 consecutive cases with anterior acute ischemic stroke treated intra-arterially during 2000-2011. Stroke severity was defined according to the National Institutes of Health Stroke Scale, the results of the procedure were defined according to the modified Thrombolysis in Cerebral Infarction score, and clinical outcome was defined according to the modified Rankin scale, with favorable outcome ≤2 at 90 days.

RESULTS

The mean admission NIHSS score was 19.4 (median, 20), with a mean time from stroke onset to groin puncture of 197 minutes (median, 171 minutes). The embolectomy tool of choice was the Amplatz GooseNeck snare (83%). Successful recanalization (modified TICI 2b +3) was seen in 74% of cases. A mRS ≤ 2 at 90 days was seen in 42% with a mortality rate of 17% and symptomatic intracerebral hemorrhage in 4%.

CONCLUSIONS

A high recanalization rate was obtained with the Amplatz GooseNeck snare without any device-related complications. Favorable outcome, mortality, and symptomatic intracerebral hemorrhage are comparable with results of newer embolectomy devices.

Effects of a self-care program on the health-related quality of life of pacemaker patients: a nursing intervention study

An experimental, multi-centre, randomized study with a nurse-led intervention was conducted with the aim of evaluating the effects on HRQoL of a 10-month self-care program for pacemaker patients. In the present study, there were no significant differences in HRQoL when comparisons were made between the experimental group and the control group. Results show two main findings for patients in the self-care program (n = 97; mean age 71 years): a significantly better HRQoL in terms of experiencing the symptoms that were the reason for pacemaker implantation, as having decreased or disappeared, and a higher level of perceived exertion in a 1 1/2-minute stair test compared with patients who had standard checkups (n = 115; mean age 73 years). It is important to actively include pacemaker patients in a self-care program while still in the acute phase in the hospital. Health care professionals should support the patient in a kind and professional manner by providing clear, relevant information, and planning a self-care program based on the nurse's assessment of the patient's needs. To enable patients to manage their life situations, training and continued education for health care professionals is necessary so that their efforts are based on a holistic approach to nursing care and recognition of the patient perspective, with emphasis on developing education and counselling for women, patients with atrial fibrillation/sick sinus disease, and patients whose pacemakers have ventricular pacing.

CSF –Neurofilament correlates with outcome after aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating event. Following the bleeding, a number of pathophysiological changes and clinical factors determine outcome. Not surprisingly, attempts to predict outcome based on a single factor have failed. The neurological status graded at admission to hospital and distributions of the blood on CT are the strongest predictors. There is evidence that cerebrospinal fluid (CSF) proteins may serve as markers of the extent of brain damage. The present study is focused on the light unit of neurofilament protein (NFL), previously not evaluated in aSAH. Lumbar puncture (LP), neurological grading according to World Federation of Neurological Surgeons (WFNS) and neurological examination according to the National Institute of Health Stroke Scale (NIHSS) were performed in 48 consecutive patients with aSAH 10-14 days after the hemorrhage. CSF-NFL concentrations were analyzed using an ELISA. Outcome was assessed after 1 year and categorised according to the extended Glasgow Outcome Scale (GOSE). A significant correlation between CSF-NFL and GOSE was detected at follow up after 1 year. CSF-NFL also correlated with WFNS and NIHSS on the day of the lumbar puncture. CSF-NFL is a biochemical marker of brain damage correlating to neurological status and long-term outcome after aneurysmal subarachnoid hemorrhage.

Patients with heart failure in primary health care: effects of a nurse-led intervention on health-related quality of life and depression

AIMS

To determine the effects of a nurse-led intervention designed to improve self-management of patients with heart failure in a primary health care setting regarding health-related quality of life and depression.

METHODS

Patients at eight primary health care centres were screened by the Diagnosis Related Groups registry for the diagnosis of heart failure and eligibility for a cluster randomised study. A total of 153 patients were included (n=78 in the intervention group, 54% males, mean age 79 years, 59% in New York Heart Association class III-IV). The intervention involved patient and family education about heart failure and self-management and monthly telephone follow-up during 12 months by a primary health care nurse.

RESULTS

The effects of the nurse-led intervention were limited. Significant differences were found in the physical dimension measured by the SF-36 health survey, and in depression measured by the Zung Self-rating Depression Scale. In comparison within groups at the 3 and 12-month follow-up, the intervention group significantly maintained their health-related quality of life measured by the SF-36 health survey, and their experience of depression measured by the Zung Self-rating Depression Scale to a greater extent than in the control group, especially among women.

CONCLUSION

A nurse-led intervention directed toward patients with heart failure in a primary health care setting resulted in limited effects between the groups, although the physical and mental status were retained during 12 months of follow-up to a greater extent than in the control group.

CSF levels of neurofilament is a valuable predictor of long-term outcome after cardiac arrest

AIMS

Prognostication of brain damage after cardiac arrest mainly relies on clinical observations. Recently, it has been shown that biochemical markers of brain damage measured in serum aid in this process. In the present study, we wanted to test the usefulness of CSF determinations of a neuronal protein, the neurofilament protein (NFL).

METHODS AND RESULTS

Lumbar punctures were performed during week 2 or 3 in 22 patients surviving cardiac arrests. CSF NFL concentrations were analysed using an ELISA. Levels were increased in cardiac arrest patients. Patients with poor outcome according to the Glasgow outcome scale (GOS), low performance at a mini mental state examination (MMSE) and dependent according to Katz at 1 year follow up had the highest NFL levels. The NFL levels correlated well with anoxia time and coma depth. High positive and negative predictive values, particularly for poor outcome according to GOS were observed.

CONCLUSIONS

Levels of CSF NFL give a reliable measure of the brain damage following cardiac arrest and the levels are highly predictive of poor outcome. This observation urges the development of sensitive serum assays of this marker to be used in the clinical setting.

Cerebrospinal fluid neurofilament and glial fibrillary acidic protein in patients with cerebral vasculitis

Few diseases in clinical medicine cause as much diagnostic consternation as central nervous system (CNS) vasculitis because of its varying modes of presentation and frequently overlapping clinical and pathological features. There are no pathognomonic clinical or laboratory findings. The purpose of the present retrospective study was to validate the use of the light subunit of neurofilament triplet protein (NFL) and glial fibrillary acidic protein (GFAP) as markers of CNS tissue damage for patients with systemic or isolated CNS vasculitis. Levels of cerebrospinal fluid (CSF) NFL and GFAP were measured using ELISAs. Both CSF NFL and CSF GFAP concentrations were significantly higher in a patient group diagnosed with CNS vasculitis (P < 0.01 and P < 0.05, respectively) than in a patient group for whom CNS vasculitis was excluded. In the future, analysis of CSF NFL in particular, but also GFAP, may be a useful complement in the difficult clinical task of diagnosing CNS vasculitis.

Neurofilament protein levels in CSF are increased in dementia

The neurofilament is the major cytoskeletal structure of myelinated axons. In this study, CSF levels of the light subunit of the neurofilament protein (NFL) were increased in patients with vascular dementia (VAD), AD, and frontotemporal dementia (FTD) compared with neurologically healthy individuals. Because NFL is localized mainly in myelinated axons, these results suggest that the degeneration of white matter in these disorders causes the increased CSF NFL levels.

Astroglial and neuronal proteins in cerebrospinal fluid as markers of CNS involvement in Lyme neuroborreliosis

Is Lyme neuroborreliosis, even in its early phase, a parenchymatous disorder in the central nervous system (CNS), and not merely a meningitic process? We quantified cerebrospinal fluid (CSF) levels of four nerve and glial cell marker proteins in Lyme neuroborreliosis patients with pretreatment durations of 7-240 days. All 23 patients had meningoradiculitis, and six had objective signs of encephalopathy. Glial fibrillary acidic protein (GFAp) pretreatment levels in CSF, and the light subunit of neurofilament protein (NFL) levels were related to clinical outcome and declined significantly after treatment (P < 0.001 and P < 0.01, respectively). NFL was detectable in 11 out of 22 patients, and pre- and post-treatment NFL levels were associated with the duration of neurological symptoms within 100 days prior to treatment. Neuron-specific enolase (NSE) concentrations also decreased after therapy (P < 0.001), while CSF levels of glial S-100 protein remained unchanged. The pretreatment duration of disease was related to postinfectious sequelae. GFAp, NSE and NFL levels in CSF are unspecific indicators of astroglial and neuronal involvement in CNS disease. The findings in the present study are in agreement with the hypothesis that early and late stages of Lyme neuroborreliosis damage the CNS parenchyma.

Detection of light subunit neurofilament and glial fibrillary acidic protein in cerebrospinal fluid of Trypanosoma brucei gambiense-infected patients

Light subunit neurofilament (NFL) and glial fibrillary acidic protein (GFAP) concentrations were determined in cerebrospinal fluid (CSF) of 34 patients with human African trypanosomiasis (HAT), five serologically positive but parasitologically unconfirmed individuals, and four healthy controls without evidence of HAT. In patients with second stage HAT (n = 30), NFL levels were abnormally elevated in 10 cases and GFAP levels in five. The astrogliosis observed in HAT and experimental models of HAT is confirmed in our study by the presence of increased GFAP levels in the CSE The abnormal NFL CSF levels reflect structural damage of nerve cells in 33 % of the second-stage patients studied. To our knowledge, this is the first time neuronal damage in HAT patients is demonstrated by using biochemical markers of brain damage in the CSF.

Female patients with congestive heart failure: how they conceive their life situation

Congestive heart failure (CHF) is a significant health problem for women, particularly elderly women. The risk factors for heart failure appear to be different in women than in men, with hypertension and diabetes playing a greater role in women and ischaemic heart disease a greater role in men. The aim of this study was to describe, from a nurse's perspective, how female patients with CHF conceive their life situation. Interview questions were designed with a focus on five dimensions: biophysical, socio-cultural, emotional, intellectual and spiritual-existential. A qualitative method was used with a phenomenographic approach, as this approach examines aspects of the surroundings as they are conceived. Five categories emerged in the results: feeling content, feeling a sense of support, feeling a sense of limitation, feeling anxiety and feeling powerless. A sense of limitation regarding working capacity and being able to support those in their surroundings causes patients with CHF to experience anxiety due to feeling insecure about themselves and in relation to their surroundings. This may result in feelings of worthlessness in women with CHF, both concerning their own capacity and the fact that they feel they are a burden to those around them. Through nursing intervention, these patients can receive help to break this vicious circle of feeling limited and powerless. This can be done by encouraging them to verbalize their feelings and set realistic goals and expectations, and by increasing their knowledge and that of their families concerning CHF and its symptoms, with a focus on self-care and existing possibilities. These measures will make it easier for women with CHF to maintain a hopeful perspective and a sense of control, competence, and self-esteem.

CSF neurofilament and glial fibrillary acidic protein in normal pressure hydrocephalus

We examined CSF levels of markers of neuronal degeneration and astrogliosis-the light subunit of the neurofilament triplet protein (NFL) and the glial fibrillary acidic protein (GFAP)-in 65 patients with normal pressure hydrocephalus (NPH). NFL was increased sixfold (864 +/- 1,538 [mean +/- SD] versus 156 +/- 81 ng/L; p < or = 0.001) and GFAP twofold (1,116 +/- 1,085 versus 637 +/- 295 ng/L; p < or = 0.01) in NPH patients compared with neurologically healthy age-matched controls. No correlation was found between any particular symptom or sign and GFAP levels in CSF. The levels of NFL, on the other hand, were higher in patients with severe symptoms compared with those with moderate or no symptoms. Furthermore, there was a correlation between a high level of NFL and gait disturbance, incontinence, psychometric incapability, and social dysfunction. A high preoperative NFL level was associated with favorable outcome after shunt surgery. This indicates that NFL is a marker of ongoing and possibly still-reversible axonal damage in NPH.

Neurofilament protein in cerebrospinal fluid: a potential marker of activity in multiple sclerosis

The neurofilament protein is a major structural protein of neurons and a marker for axonal damage. The concentrations of the light subunit of the neurofilament triplet protein (NFL) in CSF were significantly increased in patients with relapsing-remitting multiple sclerosis compared with healthy controls (p<0.001). Seventy eight per cent of patients with multiple sclerosis showed increased NFL concentrations. Significant correlations between the NFL concentration in CSF and clinical indices were discerned for disability, exacerbation rate, and time from the start of the previous exacerbation to the time of the lumbar puncture. The results suggest that axonal damage occurs during relapsing-remitting multiple sclerosis and that the damage contributes to disability and the appearance of clinical exacerbations. The concentration of NFL in CSF is a potential marker of disease activity in multiple sclerosis and might be useful in future clinical trials of multiple sclerosis.

Increased cerebrospinal fluid levels of neurofilament protein in progressive supranuclear palsy and multiple-system atrophy compared with Parkinson's disease

More reliable tools are needed for the differentiation of Parkinson's disease (PD) from other parkinsonian disorders. The neurofilament protein (NFL) and the glial fibrillary acidic protein (GFAP) are main structural proteins of axons and fibrillary astroglial cells. By using enzyme-linked immunosorbent assays, these proteins were quantified in the cerebrospinal fluid (CSF) of 49 patients referred to the Department of Neurology for diagnostic consideration or treatment of parkinsonism of different etiologies. All patients were first diagnostically evaluated by strict clinical criteria. The procedure included a neurologic and neuro-ophthalmologic examination as well as computed tomography or magnetic resonance imaging. These were performed independently and in advance of the CSF analysis. A total of 19 patients were diagnosed as having PD, 12 had progressive supranuclear palsy (PSP), and 10 had multiple-system atrophy (MSA). Eight were diagnosed as having other diseases, such as arteriosclerotic parkinsonism and undefined parkinsonian syndromes. The content of NFL was significantly higher both in the PSP group (p < 0.001) and in the MSA group (p < 0.0001) compared with the PD group. The high values of NFL indicate an ongoing neuronal degeneration affecting mainly the axonal compartment in the PSP and MSA groups, whereas there was no difference in glial involvement as measured by GFAP in the PD, PSP, and MSA groups. There was a relation between high CSF levels of NFL in the various patient groups and the occurrence of pyramidal symptoms (p < 0.001), possibly reflecting the axonal damage to the corticospinal tract. Furthermore, mortality at 24-month follow up was associated with high NFL levels (p < 0.01). We conclude that analysis of NFL in CSF may become useful in the differential diagnosis of parkinsonian syndromes.

Male patients with congestive heart failure and their conception of the life situation

Patients with congestive heart failure (CHF) are an extensive group in Sweden both with regard to prevalence and number of medical care events. As the age of the population and survival after myocardial infarction are increasing, the incidence of CHF is also on the rise. The aim of this study is to describe, from a nurse's perspective, how male patients with CHF conceive their life situation. Interview questions were designed with a focus on five dimensions: the biophysical, the sociocultural, the emotional, the intellectual, and the spiritual-existential. A qualitative method was used with a phenomenographic approach as it examines aspects of the surroundings as conceived. In the results, six categories emerged: feeling a belief in the future, gaining awareness, feeling support from the environment, feeling limitation, feeling a lack of energy and feeling resignation. The mental and physical lack of energy which patients feel easily leads to limited working capacity and social activities. This limitation may cause patients with CHF to believe that neither they nor their environment can influence their life situation and there is a risk that these patients become resigned. In order to help them get out of this vicious circle of limitation and resignation, it is important that the nurse teaches them self-care and shows them the possibilities that exist in everyday life. With increased awareness of their life situation, patients may adapt to their CHF and see that it is possible to improve their future themselves.

Patients with amyotrophic lateral sclerosis and other neurodegenerative diseases have increased levels of neurofilament protein in CSF

In the present study we describe an ELISA to quantify the light subunit of the neurofilament triplet protein (NFL) in CSF. The method was validated by measuring CSF NFL concentrations in healthy individuals and in two well-characterized groups of patients with amyotrophic lateral sclerosis (ALS) and Alzheimer's disease (AD). The levels were increased in ALS (1,743 +/- 1,661 ng/L; mean +/- SD) and AD (346 +/- 176 ng/L) compared with controls (138 +/- 31 ng/L; p < 0.0001 for both). Within the ALS group, patients with lower motor neuron signs only had lower NFL levels (360 +/- 237 ng/L) than those with signs of upper motor neuron disease (2,435 +/- 1,633 ng/L) (p < 0.05). In a second study patients with miscellaneous neurodegenerative diseases were investigated (vascular dementia, olivopontocerebellar atrophy, normal pressure hydrocephalus, cerebral infarctions, and multiple sclerosis), and the CSF NFL level was found to be increased (665 +/- 385 ng/L; p < 0.0001). NFL is a main structural protein of axons, and we suggest that CSF NFL can be used to monitor neurodegeneration in general, but particularly in ALS with involvement of the pyramidal tract.

Phosphorylated and non-phosphorylated neurofilament proteins: distribution in the rat hippocampus and early changes after kainic acid induced seizures

The regional distribution of neurofilament proteins in the rat hippocampus and their early changes after kainic acid induced seizures were investigated immunocytochemically with antibodies against light weight neurofilament, phosphorylated and non-phosphorylated heavy weight neurofilament. The light weight and non-phosphorylated heavy weight neurofilaments were distributed more unevenly than the phosphorylated neurofilament. The perikarya and processes of pyramidal cells in the CA3 field contained the highest light weight and non-phosphorylated heavy weight neurofilaments, while the perikarya of granule cells contained only few light weight neurofilament and the perikarya of CA1 pyramidal cells were even devoid of immunoreactivity of both light and heavy weight neurofilaments. The fiber staining of the light weight and non-phosphorylated heavy weight neurofilaments, especially the former, was less in the CA1 field and molecular layer of dentate gyrus. The phosphorylated neurofilament immunoreactivity was identified only in axons. Mossy fibers, the axons of granule cells, contained the light weight and phosphorylated heavy weight neurofilaments, but not the non-phosphorylated neurofilament. Seven days after the kainic acid induced seizures, the phosphorylated neurofilament staining was greatly reduced in the CA1 and inner molecular layer of the dentate gyrus, probably resulting from the axonal degeneration of the Schaffer collaterals and the commissural/associational fibers. Furthermore, the nonphosphorylated neurofilament appeared in the mossy fibers of the CA3 stratum lucidum, which normally do not express such immunoreactivity. The results indicate that the neurofilaments are altered following the neuronal degeneration and postlesional plasticity caused by the kainic acid administration. Therefore, the examination of various phosphorylated neurofilaments may offer a comprehensive understanding of major hippocampal pathways, axonal plasticity and the possible roles of neurofilaments in the hippocampus following excitotoxic insults.

Additional value of thallium-201 SPECT to a conventional exercise test for the identification of severe coronary lesions after an episode of unstable coronary artery disease

The additional value of thallium-201 SPECT to a conventional exercise test for the identification of patients with severe coronary lesions was evaluated in 170 men, one month after an episode of unstable coronary artery disease. Severe coronary lesions at coronary angiography--defined as three vessel disease, left main stenosis or proximal left anterior descending artery stenosis as part of two vessel disease--were observed in 45.9%. In the SPECT image, the left ventricular myocardium was divided into nine segments and each segment was classified as either normal (= 0), reduced uptake (= 1) or uptake defect (= 2). The sum of gradings in all segments post-exercise was denoted "SPECT score". The patients were divided into nine different groups regarding ST-depression during exercise (no ST-depression, ST-depression in 1-2 leads or > or = 3 leads) and "SPECT score" (no SPECT score, 1-3 scores or > or = 4 scores). Severe coronary lesions were, in 68% identified by SPECT score > or = 4 and in 65% by ST-depression in > or = 1 lead at exercise test. The specificity for identification of severe coronary lesions was, for both tests, 65%. SPECT score > or = 4 and/or ST-depression in > or = 3 leads identified 82% of the patients with severe coronary lesions with a specificity of 63%. Furthermore, SPECT score > or = 3 identified more patients with isolated proximal left anterior descending artery stenosis than ST-depression alone at exercise test.

PIMEX--an instructive way to study vibration exposure and work posture

The PIMEX-method (PIcture-Mix-EXposure) involves measurement of exposure with a direct-reading instrument. The signal from the instrument is superimposed to the recording from a video camera to produce a video film which continuously shows the subject at work and how exposure varies. Application can be a physical factor such as vibration. We used this new method to study vibrations from hand held grinders. Using Brüel and Kjaer miniaturized accelerometer 4374 and vibration meter 2513 we measured vibrations at the grinders main and support handles. We studied different grinders at work on the metal surface as well as at idle speed. Workers posture such as arms in under-up position was evaluated. The PIMEX-method has been encouraging to show correlation between vibration exposure, work technique and different grinders.

Comparison of threshold values between steroid and nonsteroid unipolar membrane leads

The aim of this study was to evaluate whether steroid membrane leads can reduce pacing thresholds and thereby save energy as compared to nonsteroid membrane leads. The study was a random sample, double blind test consisting of 90 patients between 49-94 years of age admitted to seven hospitals in Europe for pacemaker implantation. The two leads compared in this study had contoured activated carbon tips covered with ion exchange membranes. The leads were identical except that 30 micrograms of dexamethasone was dissolved in the ion exchange membrane of one of the leads. Normal lead implant procedures were used. Follow-up procedures were conducted at 2 weeks and 1, 3, 6, and 12 months after lead implantation. The pulse generator was programmed to an amplitude of 2.5 or 5 V and a duration of 0.5 msec. The stimulation threshold was measured using the VARIO function. The threshold was measured a total of three times in order to determine the presence of microdislocations. At the 2- and 4-week follow-ups, the stimulation threshold was significantly lower for the steroid leads than for the membrane leads without steroid (0.54 +/- 0.19 vs 0.76 +/- 0.25 V, P = 0.0005; and 0.59 +/- 0.19 vs 0.74 +/- 0.26 V, P = 0.005), but after 3 months, the threshold values were almost the same for both leads.

Upper airway irritation and small airways hyperreactivity due to exposure to potassium aluminium tetrafluoride flux: an extended case report

OBJECTIVES

22 workers, exposed to potassium aluminium tetrafluoride used as flux for soldering aluminium, were studied as clinical outpatients for symptoms of irritation of the nose, eye, skin, and airways.

METHODS

16 volunteered for spirometry with methacholine provocation test including a test for small airways function by volume of trapped gas (VTG).

RESULTS

Median (range) latency time before respiratory symptoms developed was 6 (1-60) months. Symptoms of airways irritation diminished in all subjects after flux exposure ended. The FEV1 was within the normal range in 16 of 17 subjects before the methacholine provocation test. The FEV1 decreased by > or = 20% in two out of 16 subjects after the 0.1% methacholine provocation. Four out of the 17 subjects had a high VTG before methacholine provocation. After inhalation of 0.1% methacholine eight out of 16 subjects (50%) had an abnormal increase of VTG indicating hyperreactivity in small airways.

DISCUSSION

Potassium aluminium tetrafluoride flux seems to induce an increase of bronchial reactivity in small airways. A setting of an occupational standard for potassium aluminium tetrafluoride is proposed.

Exercise echocardiography and thallium 201 single-photon emission computed tomography in male patients after an episode of unstable coronary artery disease

To compare modern, digital exercise echocardiography and thallium 201 single-photon emission computed tomography (SPECT) in patients with unstable coronary artery disease, 65 men unselected with regard to echocardiography were prospectively investigated 1 month after an episode of unstable angina or non-Q-wave myocardial infarction. Exercise echocardiography and 201Tl SPECT were performed on consecutive days in connection with a standard symptom-limited upright bicycle test and analyzed in a 9-segment model. Coronary angiography was performed in all but 1 patient and 60 patients had significant coronary lesions. Wall motion abnormalities were seen in 53 patients (81%) at rest and perfusion defects in 57 patients (88%) at the redistribution images. New or worsening of wall motion abnormalities were seen in 55 patients, either seated at peak exercise or recumbent after exercise, and 43 patients had reversible or partially reversible 201Tl scintigraphic defects (P = .02). The segmental agreement between wall motion abnormalities and scintigraphic defects was low (58%). The additional value of exercise echocardiography and 201Tl SPECT to exercise test was greatest in patients with one-vessel disease. Thus, 1 month after an episode of unstable coronary artery disease in men, there is a high incidence of significant coronary stenoses as well as signs of ischemia shown both by wall motion abnormalities during exercise echocardiography and by postexercise studies with 201Tl SPECT. Exercise echocardiography gives a higher diagnostic yield regarding occurrence of reversible ischemia.

Ambulatory ST-recording has no additional value to exercise test for identification of severe coronary lesions after an episode of unstable coronary artery disease in men

One month after an episode of unstable coronary artery disease, 95 male patients performed coronary angiography, 48 hours ambulatory ST-recording and also an exercise test. ST-depression occurred in 29.5% during the ST-recording and in 44.2% during the exercise test (p < 0.05). In patients with ST-depression at ambulatory monitoring, 79% demonstrated the same finding at the exercise test. A high risk response at the exercise test--defined as either ST-depression in > or = 3 leads, ST-depression in 1-2 leads with a maximal work load below the 60th percentile or a maximal work load below the 30th percentile regardless of the ECG reaction--occurred in 56.8%. Severe coronary lesions--defined as three vessel disease, left main stenosis or proximal left anterior descending artery stenosis as part of two vessel disease--was observed in 46.3%. Patients with a high risk exercise test response and patients with ST-depression during ST-recording had severe coronary lesions in 67% and 64% respectively. However, a high risk exercise test response occurred in 82%, while ST-depression at ambulatory monitoring was observed only in 41% of the patients with severe coronary lesions (p < 0.001). Thus, ambulatory ST-recording one month after an episode of unstable coronary artery disease in men adds no further information to a symptom limited exercise test in order to identify patients with severe coronary lesions.

ST-changes in ECG at rest or during exercise indicate a high risk of severe coronary lesions after an episode of unstable coronary artery disease

After an episode of unstable coronary artery disease, 190 patients performed a predischarge exercise test. A postdischarge exercise test and coronary angiography was performed by 172 patients after 1 month. A subgroup of 104 men performed both exercise tests with a computer-aided system. More sophisticated methods of evaluating the ECG reaction during exercise were not diagnostically superior to the simple identification of ST-depression of > or = 0.1 mV. ST-depression in ECG at rest indicated a 70% risk of severe coronary lesions and in such patients, the ECG reaction at exercise carried no additional diagnostic information. Stepwise multiple regression analysis showed that ST-depression and low maximal work load were the most important exercise variables for identification of severe coronary lesions. Using a combination of these parameters, the sensitivity and specificity for identification of severe coronary lesions were, respectively, 77% and 61% predischarge and 77% and 70% after 1 month.

Perchloroethylene-induced reduction in glial and neuronal cell marker proteins in rat brain

Rats were exposed to continuous inhalation of 300 and 600 p.p.m. of perchloroethylene for 4 and 12 weeks. Exposure to 600 p.p.m. for 4 to 12 weeks resulted in a slower increase in brain weight. Brain region weights, total proteins and DNA were decreased in frontal cerebral cortex and brain stem but not in hippocampus after exposure to 600 p.p.m. for 12 weeks. Four marker proteins were measured to monitor the specific neurotoxic effects of perchloroethylene: S-100 protein and glial fibrillary acidic protein as glial cell markers and neurone specific enolase and neurofilament 68 kD polypeptide as neuronal markers. The concentrations of glial and neuronal cytoskeletal proteins (glial fibrillary acidic protein and neurofilament 68 kD polypeptide) were reduced in frontal cerebral cortex. The total tissue contents of glial proteins (S-100 protein and glial fibrillary acidic protein) were decreased in all 3 brain regions investigated (frontal cerebral cortex, hippocampus and brain stem). Neurone specific enolase was unchanged by perchloroethylene exposure. These results indicate that exposure to perchloroethylene reduces the number of brain cells, possibly glial cells, and interferes with the metabolism of cytoskeletal elements in both glial and neuronal cells.

Glial and neuronal marker proteins in the silicone chamber model for nerve regeneration

In the present study, neuronal and Schwann cell marker proteins were used to biochemically characterize the spatiotemporal progress of degeneration/regeneration in the silicone chamber model for nerve regeneration. Rat sciatic nerves were transected and the proximal and distal stumps were inserted into a bridging silicone chamber with a 10-mm interstump gap. Using dot immunobinding assays, S-100 protein and neuronal intermediate filament polypeptides were measured in different parts of the nerve 0-30 days after transection. In the most proximal nerve segment, all the measured proteins were transiently increased. In the proximal and distal stumps adjacent to the transection, the studied proteins were decreased indicating degeneration of the nerve. Within the silicone chamber, the regenerating nerve expressed the Schwann cell S-100 protein already at 7 days, whereas the neurofilament polypeptides appeared later. These observations are corroborated by previous morphological studies. The biochemical method described provides a new and fast approach to the study of nerve regeneration.

Quantitative alterations of S-100 protein and neuron specific enolase in the rat nervous system after chronic 2,5-hexanedione exposure

The regional changes in quantities of the glial S-100 protein and the neuron specific enolase in the rat nervous system have been studied after long-term exposure to 2,5-hexanedione. The wet weights of most of the examined nervous tissues were found to be reduced, with an extensive effect seen in the brain stem. Using dot immunobinding assays, the concentrations of S-100 were found to be increased in most of the examined tissues, but unaffected in the brain stem. The total amount of S-100 per tissue was markedly reduced in the brain stem. The content of neuron specific enolase was reduced only in the brain stem. Thus the effects of 2,5-hexanedione on the nervous system varied regionally. The brain stem was severely atrophied with a reduction of neuronal as well as of glial marker proteins. Other brain regions contained increased glial cell marker proteins as signs of progressive astroglial reactions.

Thrombolysis with recombinant human tissue-type plasminogen activator during instability in coronary artery disease: effect on myocardial ischemia and need for coronary revascularization. TRIC Study Group

Two hundred five men, 40 to 70 years of age, admitted to the coronary care unit with unstable coronary artery disease (unstable angina or non-Q wave myocardial infarction), were randomized to double-blind placebo-controlled treatment with an intravenous infusion of recombinant tissue-type plasminogen activator (rTPA), 1 mg/kg body weight (maximum 100 mg) during 4 hours, in addition to aspirin, heparin, and beta-blockade. No severe complications occurred. Myocardial ischemia, defined as myocardial infarction, incapacitating angina despite medication, or signs of ischemia at the exercise test, was reduced by treatment with rTPA compared with placebo both at discharge, 53% compared with 70% (p = 0.02), and at 1 month, 61% compared with 80% (p = 0.005). Signs of myocardial ischemia during the exercise test were reduced at discharge 51.0% compared with 68% (p = 0.03) and at 1 month 48% compared with 62% (p = 0.09). Coronary angiography after 1 month showed no difference in major coronary lesions between the groups, nor was there any reduction in the number of performed coronary revascularization procedures. In conclusion, treatment with rTPA in unstable coronary artery disease in men reduced myocardial ischemia but did not significantly reduce the need for revascularization in long-term follow-up.

Proteolysis of filament proteins in glial and neuronal cells after in vivo stimulation of hippocampal NMDA receptors

An intrahippocampal injection of N-methyl-D-aspartate induced the appearance of degradation products of both the 68 kiloDalton neurofilament protein and the glial fibrillary acidic protein, as revealed by immunoblot techniques. The degradation of these two filament proteins was maximal at 10 days after the lesion. The degradation patterns were similar to those induced with calpains or calcium in vitro. There were no degradation effects on the 200 kD neurofilament protein as tested with both mono- and polyclonal antibodies. Consequently, the neuronal degeneration after excessive activation of NMDA receptors appears to involve calcium activation of proteolytic enzymes. The effects on the glial proteins are probably secondary to neuronal damage but could be related to calcium dependent processes.

Exercise echocardiography: a methodological study comparing peak-exercise and post-exercise image information

It is unclear whether echocardiography at peak bicycle exercise adds information to registrations obtained recumbent immediately after the test and what factors influence image quality. Therefore, exercise echocardiography was performed consecutively and prospectively in 66 men, unselected with regard to echocardiography, one month after an episode of unstable coronary artery disease. Of 594 segments (9 x 66), 569 (96%) were adequately visualized recumbent at rest. The corresponding figures recumbent directly after exercise, seated before exercise, and seated at peak exercise were 544 (92%), 474 (80%), and 428 (72%), respectively. In the majority of our patients, acceptable images at peak exercise were obtained for the septal region, while for the anterior, lateral, and inferior segments the success rate varied from 50 to 70%. Recumbent after exercise, the success rate was acceptable for most segments, possibly with the exception of the apical and lateral segments. Fifty-five patients developed new wall motion abnormalities or worsening of wall motion in connection with exercise. Echocardiography at peak exercise provided more information than afterwards in patients with images of good quality. However, in patients with inferior image quality, the registrations obtained recumbent after the test revealed wall motion abnormalities which were not obtained seated at peak exercise. Patients with worse image quality had significantly higher respiratory rate and weight, and rated a higher degree of dyspnoea at peak exercise than those with good quality. We conclude that in middle aged men with coronary artery disease, image acquisition at peak bicycle exercise and immediately after exercise are of complementary value.

Quantitative and qualitative alterations of neuronal and glial intermediate filaments in rat nervous system after exposure to 2,5-hexanedione

The precise mechanism for the neurotoxicity of 2,5-hexanedione is not known, but cross-linking of neurofilament proteins has been suggested as one possibility. In this study the effects of long-term exposure to 2,5-hexanedione were studied in the rat nervous system with special reference to regional changes in the quantities of neuronal and glial intermediate filaments. Using enzyme-linked immunosorbent assays the concentrations of 68- and 200-kDa neurofilament polypeptides were shown to be reduced in all brain regions studied. Similar results were obtained in the sciatic nerve. The concentration of glial fibrillary acidic protein was decreased in the cerebellar vermis and the dorsal cerebral cortex, whereas it was increased in the spinal cord, a result suggesting a regional variation in glial sensitivity. The intermediate filaments of the exposed animals were also immunoblotted using polyclonal antisera against the various neurofilament polypeptides and glial fibrillary acidic protein. In all tissues studied, several aggregates with molecular weights higher than those of the monomeric polypeptides were demonstrated. Contrary to clinical observations, these data indicate pronounced effects in both CNS and PNS and call for further studies on CNS effects in humans.

Prospective comparative study in NIDDM patients of metformin and glibenclamide with special reference to lipid profiles

Twenty-two NIDDM patients completed an open randomized cross-over study comparing metformin and glibenclamide over 1 year. The drugs had an equivalent effect on glycaemic control, but, in contrast to glibenclamide, metformin reduced body weight. Neither drug affected triglycerides, total- and LDL-cholesterol or C-peptide. Metformin caused a slight elevation of HDL-cholesterol (P less than 0.05). No serious adverse effects were observed. The results show that oral hypoglycaemic agents are not associated with undesirable effects on lipids and lipoproteins.

The effect of an N-methyl-D-aspartate lesion in the hippocampus on glial and neuronal marker proteins

The study employed an immunochemical quantification of brain cell marker proteins in addition to quantitative morphology in order to provide a more multifacetted and characterized model for an excitotoxic CNS lesion. The importance of the approach in the evaluation of the potential of neuroprotective agents is emphasized. The S-100 protein, the glial fibrillary acidic (GFA) protein, neuron specific enolase (NSE) and neuronal intermediary filament polypeptides (NF 68 and NF 200) were measured with a dot-immunobinding assay, 3-30 days after a unilateral injection of N-methyl-D-aspartate (NMDA) in the left dorsal hippocampus of the rat. After 3 days, the neuronal cell loss averaged 80% in the hippocampus. The S-100 content was reduced 3 days after injection, but was 150% of control at 30 days. GFA increased constantly from days 3 to 30. The neuronal marker proteins were all markedly reduced 7 days after injection. However, at 30 days, NF 68 and NF 200 were close to control (80%). Increasing content would reflect regeneration and sprouting of neurites. The content of the neuronal cytoplasmic marker, NSE, was significantly lower than control also at 10 and 30 days, although a gradual recovery could be traced.

A simple quantitative dot-immunobinding assay for glial and neuronal marker proteins in SDS-solubilized brain tissue extracts

Immunoassays for quantitative determinations of the S-100 protein, the glial fibrillary acidic protein, the neuron specific enolase and the neurofilament proteins with molecular weight of 68 and 200 kDa in hot SDS sonicated rat brain extracts have been developed and characterized. The assays utilize a dot immunobinding technique, poly- or monoclonal antibodies and 125I-protein A. The SDS-sonication procedure was not found to affect the radioactivity recovery in the assay of the soluble S-100 protein or the neuron specific enolase. All 5 antigens can be measured with a within-assay variance below 10%. Even at a coefficient of variation less than or equal to 5%, the working ranges are approximately 30-100-fold with regard to the different antigens. It was found that gelatin-coated nitrocellulose membranes considerably increase the recovered radioactivity in the assay of the purified bovine S-100 protein, possibly by protein-protein interaction. This effect was not observed when SDS-sonicated rat brain extracts were assayed. The assay appears to be reproducible, convenient and rapid, and provides a high degree of precision in the determination of large number of samples.

Polyclonal antisera to the individual neurofilament triplet proteins: a characterization using ELISA and immunoblotting

In this article, the preparation and characterization of polyclonal rabbit antisera against the individual polypeptides of bovine neurofilament (68, 150, and 200 kilodaltons) is described. Selected antisera against the 68- and 150-kilodalton neurofilament polypeptides were specific for the corresponding antigen in homogenates of bovine, rat, and human brain as judged by immunoblots. The antisera against the 200-kilodalton neurofilament polypeptide cross-reacted to some extent with the 150-kilodalton neurofilament polypeptide, especially with the human antigen. The most specific antisera were used to develop an enzyme-linked immunosorbent assay (ELISA), and the cross-reactivities between the antisera and the different bovine and rat neurofilament polypeptides were determined. Contrary to the results in the immunoblots, the antiserum against the 200-kilodalton neurofilament polypeptide was subunit-specific, as was the 150-kilodalton antiserum. The 68-kilodalton antiserum displayed a minute cross-reactivity against bovine 150- and 200-kilodalton neurofilaments, but it cross-reacted somewhat more with the rat 150- and 200-kilodalton antigens. Even so, the subunit specificity of the antisera is high enough to enable the development of a quantitative ELISA for determination of the individual bovine or rat neurofilament polypeptides in a mixture. This study is the necessary preparation for such an assay.

Presence of nerve growth factor-like immunoreactivity in carcinoid tumour cells and induction of a neuronal phenotype in long-term culture

Mid-gut carcinoid tumour cells expressed a neuronal phenotype, observed and characterized immunocytochemically in long-term culture. Initially the culture contained a main population of spherical tumour cells with granules immunopositive for serotonin (5-HT) and tachykinins (TK). Production and secretion of these substances into media was verified biochemically. Cytoplasmic granules with 5-HT-like immunoreactivity (5-HT-LI) were markedly reduced during culture, while granules with TK-LI were unchanged in number, corresponding to the biochemical findings. After a few days in culture, tumour cells were flattened and fine neurite-like processes extended. After 2-3 weeks many endocrine tumour cells had converted to neuron-like cells with slender cell processes containing granules with TK-LI. Varicose enlargements and apparent growth cones were observed. When neurites were extended, 50-80% of the neuron-like cells were positive with antisera against the neurofilament triplet. Cells of both endocrine and neuronal phenotypes were positive with antisera against tetanustoxin, Thy 1-antigen, neuron-specific enolase, synapsin and a synaptic vesicle protein (p 38) supporting the concept of these tumour cells as para-neurons. Intermediate filaments, studied with monoclonal anti-vimentin, were found in all cells. Filaments were also observed ultrastructurally. Initially, nerve growth factor (NGF)-LI was found in granules of all spherical tumour cells. When neuritic processes were extended, the cells appeared to lose these granules. After 40 days in culture, NGF-LI was absent or very sparse. The studies indicate autocrine secretion of a growth factor, reacting with the NGF antiserum, by cultured mid-gut carcinoid tumour cells inducing a neuronal phenotype with enhanced NF and TK synthesis and suppressed 5-HT synthesis. In bioassay systems the culture media caused a delayed neurite reaction on PC12 cells, but no reaction on chick ciliary ganglion cells, indicating that the factor is not authentic NGF.

Detection limits of different approaches in behavioral teratology, and correlation of effects with neurochemical parameters

Five laboratories collaborated in the evaluation of detection limits of different testing concepts in behavioral teratology. In one laboratory, rat dams were treated by gavage with five doses of methylmercury (0.0, 0.25, 0.05, 0.5, and 5.0 mg/kg/day). The treatment period was restricted to days 6 to 9 of gestation. The usual reproduction parameters were assessed in the dams. The offspring (88-99 per group) were subjected to a routine developmental and behavioral testing battery. After completion of these tests, random samples of the animals were further investigated in four other laboratories using the following techniques: auditory startle habituation, visual discrimination and figure-8 activity monitor; wheel-shaped activity monitor and spatial alternation operant conditioning; two-compartment locomotor activity, passive avoidance and male ultrasonic vocalization during sexual behavior; assays of the weight of different brain areas, their glial fibrillary acidic (GFA) protein and S-100 protein concentration. The following dose-dependent effects were noted in ascending dose sensitivity order: delayed vaginal opening; increased and more variable passiveness in spatial alternation; impaired swimming behavior, increased GFA protein concentration in the cerebellar vermis; increased auditory startle amplitude, decreased intertrial interval pokes in the visual discrimination test, increased percentage of visits in passive area of figure-8 activity monitor, increased path iteration frequencies and decreased local activity in the wheel-shaped activity monitor, decreased locomotor activity in the two-compartment monitor, increased cerebellar vermis weight, and decreased S-100 protein in the hippocampus. Therefore, this study showed comparable sensitivities for the behavioral testing battery, for some automated multiparametric test systems and for the neurochemical assays.

Antibodies in cerebrospinal fluid of some Alzheimer disease patients recognize cholinergic neurons in the rat central nervous system

The etiology of Alzheimer disease is unclear. However, immunological aberrations have been suggested to be critical factors in the pathogenesis of this neurodegenerative disease. This study was carried out to investigate if cerebrospinal fluid (CSF) from Alzheimer disease patients contains antibodies that recognize specific neuronal populations in the rat central nervous system. The results indicate that in a subgroup of patients this is indeed the case. The antibodies reported in this study have the following properties: (i) they recognize neuronal populations and components in the medial septum and spinal motor neurons in rats perfused with a mixture that fixes small neurotransmitter molecules; (ii) adsorption of the patient CSF with staphylococcal protein A-Sepharose and using a polyclonal antiserum against human IgG3 indicates that the immunocytochemical reaction in these brain regions is mainly due to the subclass IgG3; and (iii) the CSF immunocytochemical reaction is blocked by preincubation of the sections with a rabbit anti-acetylcholine antiserum. These results provide evidence that antibodies in the CSF of some, but not all, Alzheimer disease patients recognize acetylcholine-like epitopes in cholinergic neurons in the rat central nervous system.

A rapid HPLC method to separate the triplet proteins of neurofilament

In this article a fast HPLC technique to separate the individual neurofilament proteins is described. Highly pure fractions of the three neurofilament proteins can be obtained. As much as 50 mg of each neurofilament polypeptide can be separated from a crude neurofilament protein preparation in one step in less than 2 h. The short separation time is of importance in minimizing degradation, especially of the 150-kilodalton neurofilament polypeptide.

Effects of low-dose inhalation of three chlorinated aliphatic organic solvents on deoxyribonucleic acid in gerbil brain

Young adult Mongolian gerbils (Meriones ungiculatus) were continuously exposed by inhalation to 1,1,1-trichloroethane at the Swedish occupational exposure limit (70 ppm), to methylene chloride at three times (210 ppm) the Swedish occupational exposure limit (70 ppm), and to perchloroethylene at three times (60 ppm) the Swedish occupational exposure limit (20 ppm), for three months, followed by a four-month postexposure solvent-free period. The concentrations of deoxyribonucleic acid (DNA) were then determined in different regions of the gerbil central nervous system. It was observed that the DNA concentrations in several brain regions were decreased in the exposed animals. It was found that 1,1,1-trichloroethane induced these alterations in many more brain areas at its Swedish occupational exposure limit than the other solvents studied at threefold their Swedish occupational exposure limits. The results suggest that all the solvents decrease cell density by inhibiting the slow acquisition of DNA or by inducing cell death in some sensitive brain areas and that 1,1,1-trichloroethane should not be regarded as harmless as previously stated.

Chronic effects of dichloromethane on amino acids, glutathione and phosphoethanolamine in gerbil brain

Mongolian gerbils were exposed to dichloromethane for three months by continuous inhalation at 210 ppm. Total free tissue amino acids, glutathione, and phosphoethanolamine were determined in the vermis posterior of the cerebellum and the frontal cerebral cortex. These two brain areas were chosen because humans occupationally exposed to dichloromethane have shown abnormalities in the electroencephalogram of the frontal part of the cerebral cortex. This study showed that long-term exposure of gerbils to dichloromethane (210 ppm) for three months leads to decreased levels of glutamate, gamma-aminobutyric acid, and phosphoethanolamine in the frontal cerebral cortex, while glutamine and gamma-aminobutyric acid are elevated in the posterior cerebellar vermis.