Clozapine-associated elevation of plasma cholinesterase

OBJECTIVE

The goal of this study was to identify adverse effects of the atypical neuroleptic clozapine on liver function and lipid metabolism.

METHODS

Data which included serum levels of clozapine and its hepatic metabolite N-desmethyl clozapine were collected from medical records of patients treated with clozapine and controls.

RESULTS

We identified a clozapine-associated marked elevation of plasma cholinesterase (ChE) with unchanged levels of AST, ALT or g-GT. ChE was correlated to the serum level of clozapine and even closer to N-desmethyl clozapine. For the total patient group we observed significant correlations of ChE with the body-mass index and body weight. However, clozapine-treated patients and controls did not differ with regard to body-mass index, triglycerides, and cholesterol.

CONCLUSION

We report for the first time a clozapine-associated and dose-dependent elevation of plasma ChE, which may be related to clozapine-associated effects on hepatic lipid metabolism or ChE enzyme induction.

[Glutamatergic neurotransmission in schizophrenics]

Glutamate is the most abundant amino acid in the brain, where it plays an important role as a well-established major excitatory neurotransmitter in the central nervous system. It has been suggested that reduced glutamate neurotransmission may be involved in the pathophysiology of schizophrenia. The glutamate hypothesis of schizophrenia postulates alterations in the glutamatergic system as an important neurobiochemical event in the pathophysiology of this group of psychotic disorders. An altered glutamate release from synaptosomes including a hypofunction of different glutamate receptors (i.e. NMDA receptors) from different brain areas have previously been reported. Furthermore, partial agonists at the glycine co-agonist site of the NMDA receptor might be a new approach in the treatment of schizophrenic symptoms but further studies are necessary to clarify the role and efficacy of these substances in schizophrenia. Changes in the glutamatergic cortico-striatal connections in schizophrenia could precipitate a potential perceptive overstimulation of the neocortex from thalamic input and an inhibiting influence of the striatum on the thalamus would modulate the information input of the cortex, thereby possibly counteracting the disturbed information processing which is relatively characteristic for schizophrenic psychoses.

Moderate alcohol consumption in social drinkers raises plasma homocysteine levels: a contradiction to the 'French Paradox'?

Evidence from observational studies suggests that elevated levels of homocysteine are associated with an increased risk of cardiovascular diseases. We assessed whether moderate alcohol intake in healthy social drinkers, suggested to be cardioprotective according to the 'French paradox', influences the cardiovascular risk factor homocysteine. A total of 60 normal nourished subjects who had no evidence of vascular disease or other risk factors for hyperhomocysteinaemia were assigned to receive mineral water or 30 g of alcohol per day (as beer, red wine or spirits) for a period of 6 weeks. Homocysteine levels of social drinkers, independent of which beverage was consumed, increased during the observation. We postulate that elevated levels of homocysteine in social drinkers with regular moderate alcohol intake are at risk of developing cardiovascular diseases, which contradicts the suggested cardioprotection of alcohol according to the 'French paradox'.

Fixation-off sensitivity in an adult with symptomatic occipital epilepsy

An adult patient had EEG occipital spike fixation-off sensitivity and spontaneous occipital seizures due to perinatal asphyxia with bioccipital hemorrhage. EEG abnormalities consisted of repetitive posterior spikes that occurred when the eyes were closed and other conditions of fixation-off. Magnetic resonance imaging (MRI) documented severe posterior lesions with wallerian degeneration of the optic radiation. Electron capture detector single-photon emission computed tomography (ECD-SPECT) during the state of fixation-off showed regional hyperperfusion in the right posterior regions. We suggest that partial denervation of the primary visual cortex in this patient resulted in an increased cortical excitability and that the inhibitory effect of central vision and fixation leads to a suppression of spontaneous epileptic activity. This unusual symptomatic case may serve as a model for the pathophysiology in the more often reported cases of idiopathic benign epilepsy syndrome of childhood.

Risk assessment of alcohol withdrawal seizures with a Kohonen feature map

Recently, it has been suggested that alcohol-induced hyperhomocysteinaemia in patients suffering from chronic alcoholism might be a risk factor for alcohol withdrawal seizures. In the present follow-up study 12 patients with chronic alcoholism who suffered from withdrawal seizures had significantly higher levels of homocysteine (Hcy) on admission (71.43 +/- 25.84 mol/l) than patients (n = 37) who did not develop seizures (32.60 +/- 24.87 mol/l; U = 37.50, p = 0.0003). Using a logistic regression analysis, withdrawal seizures were best predicted by a high Hcy level on admission (p < 0.01; odds ratio 2.07). Based on these findings we developed an artificial neural network system (Kohonen feature map, KFM) for an improved prediction of the risk of alcohol withdrawal seizures. Forty-nine patients with chronic alcoholism (12 with alcohol withdrawal seizures and 37 without seizures) were randomized into a training set and a test set. Best results for sensitivity of the KFM was 83.3% (five of six seizure patients were predicted correctly) with a specificity of 94.4% (one false positive prediction of 19 patients). We conclude that in patients with alcohol-induced hyperhomocysteinaemia the KFM is a useful tool to predict alcohol withdrawal seizures.

Homocysteine and alcoholism

Chronic alcohol consumption can induce alterations in the function and morphology of most if not all brain systems and structures. However, the exact mechanism of brain damage in alcoholics remains unknown. Partial recovery of brain function with abstinence suggests that a proportion of the deficits must be functional in origin (i.e. plastic changes of nerve cells) while neuronal loss from selected brain regions indicates permanent and irreversible damage. There is growing evidence that chronic alcoholism is associated with a derangement in the sulfur amino acid metabolism. Recently, it has been shown that excitatory amino acid (EAA) neurotransmitters and homocysteine levels are elevated in patients who underwent withdrawal from alcohol. Furthermore, it has been found that homocysteine induces neuronal cell damage by stimulating NMDA receptors as well as by producing free radicals. Homocysteine neurotoxicity via overstimulation of N-methyl-D-aspartate receptors may contribute to the pathogenesis of both brain shrinkage and withdrawal seizures linked to alcoholism.

Molecular biology of Alzheimer's dementia and its clinical relevance to early diagnosis and new therapeutic strategies

Over the past few years, molecular biological research has considerably deepened our understanding of the pathophysiological basis of Alzheimer's dementia (AD). Although different genetic origins of the disease have been identified, all of the findings point to a common terminal sequence in familial AD. This consists of an increased production of beta-amyloid peptides from beta-amyloid precursor protein. For the cases of sporadic AD, which far outweigh the number of cases of familial AD, an impaired catabolism of the beta-amyloid peptides may also be pathophysiologically decisive according to the latest findings. Research into the molecular level of AD makes it possible to identify points of attack for rational drug treatment of the disease, while molecular markers of AD are increasingly being used as a part of early and differential neurochemical diagnostics.

[New antidepressant drugs. What side effects and interactions are to be expected?]

The new antidepressants, selective serotonin reuptake inhibitors (SSRI), selective serotonin noradrenalin reuptake inhibitors (SSNRI) and selective noradrenalin reuptake inhibitors (SNRI) have few clinically relevant side effects. Overall, the new antidepressants are better tolerated and cause fewer side effects than the classical tricyclic antidepressants (TCA). They have virtually no anticholinergic effects, a low level of toxicity, and produce no psychomotoric or cognitive impairment. Both the frequency and severity of gastrointestinal and CNS side effects, as well as tremor, are low. The results of the drug safety program (AMSP) confirm the good tolerability and low clinical side effects of these new substances.

Oxidative stress and an altered methionine metabolism in alcoholism

The exact mechanism of brain atrophy in patients with chronic alcoholism remains unknown. There is growing evidence that chronic alcoholism is associated with oxidative stress and with a derangement in sulphur amino acid metabolism (e.g. ethanol-induced hyperhomocysteinemia). Furthermore, it has been reported that homocysteine induces neuronal cell death by stimulating N-methyl-D-aspartate receptors as well as by producing free radicals. To further evaluate this latter hypothesis we analysed serum levels of both homocysteine and markers of oxidative stress (malondialdehyde) in alcoholic patients who underwent withdrawal from alcohol. Homocysteine and malondialdehyde were quantified by high performance liquid chromatography (HPLC) in serum samples of 35 patients (active drinkers). There was a significant correlation (P<0. 01) between blood alcohol concentration and elevated homocysteine (Spearman's r=0.71) and malondialdehyde (r=0.90) levels on admission. In addition, homocysteine and malondialdehyde levels were found to be significant decreased after 3 days of withdrawal treatment (Wilcoxon test: homocysteine, Z=-5.127; malondialdehyde, Z=-3.120; P<0.01). We postulate that excitatory neurotransmitters and mechanisms of oxidative stress in patients with chronic alcoholism may partly mediate excitotoxic neuronal damage and hereby cause brain shrinkage.

Plasma homocysteine is a predictor of alcohol withdrawal seizures

An adaptive consequence of prolonged ethanol consumption is a compensatory up-regulation of NMDA receptors in certain brain areas. Taking into account that homocysteine and its breakdown products (i.e. homocysteic acid) are putative neurotransmitters and agonists at the NMDA receptor, the aim of this study was to assess the influence of levels of homocysteine on alcohol withdrawal seizures. Six patients with chronic alcoholism who suffered from withdrawal seizures had significantly higher levels of homocysteine on admission (84.7 +/- 29.8 micromol/l) than patients (n = 26) who did not develop seizures (30.2 +/- 23.2 micromol/l; U = 8.0, p = 0.0007). Furthermore, seizure patients had significantly lower levels of folate and significantly higher blood alcohol concentrations. Using a logistic regression analysis, withdrawal seizures were best predicted by a high homocysteine level on admission (p < 0.01; odds ratio = 1.05). Homocysteine levels on admission may be a useful screening method to identify patients at risk for withdrawal seizures.

Elevated homocysteine levels in alcohol withdrawal

Ethanol exerts its behavioural effects largely by interacting with receptors for brain neurotransmitters. However, the molecular mechanisms involving these interactions and the pathogenesis of alcohol-withdrawal symptomatology are still not well understood. Until recently, no data were available about homocysteine (Hcy) levels in acute alcohol intoxication of chronic alcoholics and in patients undergoing withdrawal from alcohol. Hcy, blood-alcohol concentrations, vitamins B6, B12, and folate concentrations were assessed in 29 chronic alcoholics, who underwent withdrawal from alcohol. We observed increased Hcy levels in most patients. Hcy levels steadily decreased during the observation period. We postulate that hyperhomocysteinaemia and excitatory amino acid neurotransmitters, by their agonism at the N-methyl-D-aspartate receptor, may partly mediate alcohol-associated withdrawal symptomatology. The importance of assessing serum Hcy levels in order to detect methylation deficiency in patients with chronic alcoholism and for possible therapeutic strategies is discussed.

[Diagnostic steps in Alzheimer dementia before treatment with new antidimentives]

The dementia of the Alzheimer type (DAT) is a chronic neurodegenerative illness. It will continue to increase because of rising life expectancy in the industrialized countries. Apart from the physicians interest to treat, there is also an economically justified interest to reduce the disease progression in this group of patients. The main intention of the treating physicians is to keep their patients independent as long as possible. Up to now Alzheimer's disease can only be treated symptomatically. The verified diagnosis of DAT still depends on the neuropathological investigation of brain tissue. Therefore the clinical diagnosis of DAT during lifetime should be supported by chemical analysis of typical changes in the cerebrospinal fluid (CSF) at an early stage. Meanwhile, several therapeutics with proven effectiveness in clinical studies are certified for the symptomatic treatment of DAT. However, these therapeutics are still relatively expansive. Due to this fact the clinical diagnosis of DAT should be supported by clinical-chemical markers before the beginning of such a treatment. In this paper we present the diagnostic steps in dementia patients, who are examined in our departments. Patients suspicious of DAT always are asked for a spinal tap in addition to other diagnostic tools. In case of a typical clinical constellation, the exclusion of a primarily vascular dementia as well as the proof of decreased A beta 1-42 peptides and an increased tau protein in CSF we recommend the new drugs for DAT as meaningful and justified therapeutics to yield optimal treatment.

[Follow-up study after enteral manganese poisoning: clinical, laboratory and neuroradiological findings]

Manganese intoxication is an unusual, severe form of intoxication. This report deals with a patient now 80 years old who accidentally ingested a solution of potassium permanganate for a period of at least 4 weeks 14 years ago. Since then, the patient suffers from a mild parkinsonian syndrome and distally accentuated polyneuropathies. Psychiatric disorders, especially demential or depressive symptoms, were not observed. Manganese analysis of his hair still shows a clear increase in manganese concentration. The MRI of his brain showed no pathological changes, in particular none of those often described with symmetric signal elevation in T1 in the area of the basal ganglia. In this study, we present clinical, laboratory, and neuroradiological findings. Unusual in this case with a short exposition is the long duration and clinical improvement without L-dopa treatment.

Creutzfeldt-Jakob disease and oxidative stress

OBJECTIVES

Substantial evidence supports the hypothesis that oxygen free radicals are involved in various neurodegenerative disorders. To assess the presence of oxidative stress in Creutzfeldt-Jakob disease (CJD) we examined the concentrations of malondialdehyde (MDA) as an established marker of lipid peroxidation.

MATERIAL AND METHODS

MDA was quantified by high performance liquid chromatography (HPLC) in cerebrospinal fluid (CSF; n=12) and in serum (n=11) samples of CJD patients and healthy controls (n = 15).

RESULTS

Mean values in healthy controls: 2.56 nmol/ml +/- 0.46 (CSF) and 1.94 nmol/ ml +/- 0.67 (serum); mean values in CJD patients: 2.64 nmol/ml +/- 0.67 (CSF) and 1.68 nmol/ml +/- 0.79 (serum). No significant (P>0.05) difference between CJD patients and controls was observed.

CONCLUSIONS

The results indicated that the CSF and serum of CJD patients showed no higher endogenous levels of MDA as compared to normal healthy controls. These findings provide no evidence for an additional role of oxidative stress in the pathogenetic mechanism underlying CJD neurodegeneration.

A prospective PMS study to validate the sensitivity for change of the D-scale in advanced stages of dementia using the NMDA-antagonist memantine

The present postmarketing surveillance (PMS) study is the first large scale systematic and prospective clinical trial of pharmacotherapeutic intervention in advanced stages of dementia. Within a validation program this study aimed at demonstrating the sensitivity of the D-Scale of change (DS-C) for measuring ADL-function. Efficacy of treatment with the NMDA-antagonist memantine was investigated in 531 patients with advanced dementia employing a parallel group design that stratified patient cohorts by severity according to GDS stages (Reisberg, 1992). Efficacy was determined on two independent levels: by the assessment of the physicians' Clinical Global Impression of Change (CGI-C) at the end of a 6-week observation period, and by the assessment of change in elementary ADL-functions by the caregivers using the D-Scale-of-Change. With the D-Scale-of-Change the caregivers can assess a change in broad functional items, i.e. cognitive and motor functions and also elementary functions of daily life. The effect size of this improvement increased constantly during the observation period. Even in patients of GDS stage 7 an improvement could be measured. These results were also seen by the physicians, who recorded an overall clinical improvement in 75.5% of the patients after 6 weeks. Tolerability evaluations resulted in the ratings "very well" by 59.5% or "well" by 35.0% of the patients. No serious adverse drug reactions occurred. A correlation analysis demonstrated a high congruency of both assessments. Furthermore, the observed time course of these improvements paralleled with the time course of symptomatic benefit by effects of memantine that had been repeatedly demonstrated in randomised, double-blind, placebo-controlled studies in mild to moderate dementia. Together with the evaluation of the scale-properties of the D-Scale for assessment of severity the D-Scale and the D-Scale-of-Change can be regarded as validated.