AGNP Consensus Guidelines for Therapeutic Drug Monitoring in Psychiatry: Update 2011

Therapeutic drug monitoring (TDM), i. e., the quantification of serum or plasma concentrations of medications for dose optimization, has proven a valuable tool for the patient-matched psychopharmacotherapy. Uncertain drug adherence, suboptimal tolerability, non-response at therapeutic doses, or pharmacokinetic drug-drug interactions are typical situations when measurement of medication concentrations is helpful. Patient populations that may predominantly benefit from TDM in psychiatry are children, pregnant women, elderly patients, individuals with intelligence disabilities, forensic patients, patients with known or suspected genetically determined pharmacokinetic abnormalities or individuals with pharmacokinetically relevant comorbidities. However, the potential benefits of TDM for optimization of pharmacotherapy can only be obtained if the method is adequately integrated into the clinical treatment process. To promote an appropriate use of TDM, the TDM expert group of the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie (AGNP) issued guidelines for TDM in psychiatry in 2004. Since then, knowledge has advanced significantly, and new psychopharmacologic agents have been introduced that are also candidates for TDM. Therefore the TDM consensus guidelines were updated and extended to 128 neuropsychiatric drugs. 4 levels of recommendation for using TDM were defined ranging from "strongly recommended" to "potentially useful". Evidence-based "therapeutic reference ranges" and "dose related reference ranges" were elaborated after an extensive literature search and a structured internal review process. A "laboratory alert level" was introduced, i. e., a plasma level at or above which the laboratory should immediately inform the treating physician. Supportive information such as cytochrome P450 substrate- and inhibitor properties of medications, normal ranges of ratios of concentrations of drug metabolite to parent drug and recommendations for the interpretative services are given. Recommendations when to combine TDM with pharmacogenetic tests are also provided. Following the guidelines will help to improve the outcomes of psychopharmacotherapy of many patients especially in case of pharmacokinetic problems. Thereby, one should never forget that TDM is an interdisciplinary task that sometimes requires the respectful discussion of apparently discrepant data so that, ultimately, the patient can profit from such a joint effort.

[Removal of the laryngeal mask airway in the post-anesthesia care unit. A means of process optimization?]

BACKGROUND

Removal of the laryngeal mask airway in the post-anesthesia care unit could potentially contribute to a faster turnover from one operation to the next. The aim of this study was, therefore, to obtain an insight into the potential time saving and the safety of planned removal of the ProSeal™-LMA (PLMA) in the post-anesthesia care unit.

METHODS

In this study 120 adult patients with American Society of Anesthesiologists (ASA) classification I-II, age range 18-85 years, undergoing a surgical procedure under general anesthesia in which the PLMA was used were randomly assigned to one of two groups. In group I, the PLMA was removed in the awake patient in the operating room close to the end of the procedure. In group II, the anesthetised but spontaneously breathing patients were moved to the recovery room and the PLMA removed when the patient was awake. The anesthesia technique was standardized [balanced, sevoflurane, fentanyl, bispectral index-guided (BIS) target value=35±5] and identical in both groups until randomization. Patients were breathing room air during transport to the recovery room. Different time intervals as well as the incidence of critical incidents were compared between groups. An oxygen saturation (S(p)O(2)) value <95% was considered a clinically relevant and S(p)O(2) values <90% as clinically critical O(2)-desaturation.

RESULTS

Removal of the PLMA took place after an average of 4.9±5.1 min in group I and after 19.5±9.6 min in group II. There was no difference in the availability of the anesthetist in the operating room for the following procedure between groups (group I: 12±5.6 min vs. group II: 10.7±4.2 min, p>0.05) despite the fact that patients of group II left the operating room faster (4.9±3.9 min) than patients of group I (7.1±5.1 min, p<0.01). In group II patients were ready for discharge (White score=12) from the recovery room later (13.2±8.2 min) than in group I (3.6±4.8 min, p<0.01). There were no significant differences in other process related time intervals between group I and group II: duration of the operation (113.2±45.9 min vs. 105.3±42.6 min), duration of dressing (5.1±3.7 min vs. 4.6±2.8 min), duration of transport to the recovery room (3.9±1.3 min vs. 3.6±1.3 min) and information at end of surgery by the surgeon (22.5±9.3 min vs. 22.4±10.5 min). The incidence of clinically relevant as well as clinically critical O(2) desaturation at the time of recovery room arrival (S(p)O(2)≤90%) was increased in group II with 33.3% vs. 56.6% and 13.3% vs. 6.7%, p<0.01, respectively.

CONCLUSION

Planned PLMA removal in the recovery room after BIS-guided balanced anesthesia did not enable the anesthetist to be available earlier for induction of anesthesia in the following patient. Hence the anesthetist could not contribute to a faster turnover of cases. Obviously, with the type of close communication between surgeon and anesthetist dictated by the study protocol (announcement of expected end of surgery by the surgeon 20 min before end of surgery) it is possible for the patient to regain consciousness within a very small time window following the end of surgery. Following this kind of protocol, postponement of removal of the LMA in the recovery room does not seem to be attractive neither from a clinical nor an economic point of view. In contrast, removal of LMA in the recovery room should be restricted to occasional cases with an abrupt end of the operation or prolonged emergence from anesthesia. The obvious risk of hypoxemia necessitates continuous O(2) application and S(p)O(2) monitoring during transport to the recovery room.

AGNP consensus guidelines for therapeutic drug monitoring in psychiatry: update 2011

Therapeutic drug monitoring (TDM), i. e., the quantification of serum or plasma concentrations of medications for dose optimization, has proven a valuable tool for the patient-matched psychopharmacotherapy. Uncertain drug adherence, suboptimal tolerability, non-response at therapeutic doses, or pharmacokinetic drug-drug interactions are typical situations when measurement of medication concentrations is helpful. Patient populations that may predominantly benefit from TDM in psychiatry are children, pregnant women, elderly patients, individuals with intelligence disabilities, forensic patients, patients with known or suspected genetically determined pharmacokinetic abnormalities or individuals with pharmacokinetically relevant comorbidities. However, the potential benefits of TDM for optimization of pharmacotherapy can only be obtained if the method is adequately integrated into the clinical treatment process. To promote an appropriate use of TDM, the TDM expert group of the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie (AGNP) issued guidelines for TDM in psychiatry in 2004. Since then, knowledge has advanced significantly, and new psychopharmacologic agents have been introduced that are also candidates for TDM. Therefore the TDM consensus guidelines were updated and extended to 128 neuropsychiatric drugs. 4 levels of recommendation for using TDM were defined ranging from “strongly recommended” to “potentially useful”. Evidence-based “therapeutic reference ranges” and “dose related reference ranges” were elaborated after an extensive literature search and a structured internal review process. A “laboratory alert level” was introduced, i. e., a plasma level at or above which the laboratory should immediately inform the treating physician. Supportive information such as cytochrome P450 substrate and inhibitor properties of medications, normal ranges of ratios of concentrations of drug metabolite to parent drug and recommendations for the interpretative services are given. Recommendations when to combine TDM with pharmacogenetic tests are also provided. Following the guidelines will help to improve the outcomes of psychopharmacotherapy of many patients especially in case of pharmacokinetic problems. Thereby, one should never forget that TDM is an interdisciplinary task that sometimes requires the respectful discussion of apparently discrepant data so that, ultimately, the patient can profit from such a joint eff ort.

Transcriptional alterations under continuous or pulsatile dopaminergic treatment in dyskinetic rats

Continuous dopaminergic treatment is considered to prevent or delay the occurrence of dyskinesia in patients with Parkinson's disease (PD). Rotigotine is a non-ergolinic D(3) > D(2) > D(1) dopamine-receptor agonist for the treatment of PD using a transdermal delivery system providing stable plasma levels. We aimed to investigate the differential influence on gene expression of pulsatile L: -DOPA or rotigotine versus a continuous rotigotine treatment. The gene expression profile within the nigro-striatal system of unilateral 6-hydroxydopamine-lesioned rats was assessed in order to differentiate potential changes in gene expression following the various treatment using Affymetrix microarrays and quantitative RT-PCR. The expression of 15 genes in the substantia nigra and of 11 genes in the striatum was altered under pulsatile treatments inducing dyskinetic motor response, but was unchanged under continuous rotigotine treatment that did not cause dyskinetic motor response. The route of administration of a dopaminergic drug is important for the induction or prevention of motor abnormalities and adaptive gene expressions. The decline of neurotrophin-3 expression under pulsatile administration was considered of particular importance.

Microglia activation is related to substantia nigra echogenicity

Hyperechogenicity of the substantia nigra (SN) is a sensitive marker for Parkinson's disease (PD). Previously, a relation between SN echogenicity and iron as well as neuromelanin content could be described in 60 human brains. In the present study on a subset of 33 brains, SN echogenicity was found to be correlated with microglia activation (ρ = 0.46, p = 0.008) after correction for iron and neuromelanin content. These findings strengthen the hypothesis of a close pathophysiological connection between SN hyperechogenicity and PD pathology.

Case report: intoxication with high dose of long-acting methylphenidate (Concerta(®)) in a suicidal 14-year-old girl

A 14-year-old girl with suicidal ideation was presented to the paediatric hospital about 2 h after ingestion of 21 long-acting methylphenidate (MPH) 54-mg tablets (1,134 mg Concerta(®)). At admission signs of sympathomimetic syndrome were observed like agitation, visual hallucinations, slight hypertension, and sinus tachycardia. Treatment included prevention of absorption (30 g activated charcoal orally) and careful observation related to the overstimulation of the sympathic system. Despite the intake of charcoal, the serum concentrations of MPH were 107 and 93 ng/ml 2.5 and 22 h after ingestion of MPH tablets. No support of vital functions was necessary. The girl made a full recovery and was discharged after 3 days of care at the paediatric clinic and referred to the child and adolescent psychiatric department. Exposure to a huge overdose of long-acting MPH exhibited acute sympathomimetic toxicity but no life-threatening symptoms in this patient. Thus this case report suggests that patients intoxicated with high dose long-acting MPH formulations can recover without sequelae when managed properly.

Anti-melanin antibodies are increased in sera in Parkinson's disease

An increasing body of research suggests that a number of immune mechanisms play a role in degenerative pathways in Parkinson's disease (PD). In the current work we investigated a posited humoral immune response in this disorder. Sera from PD patients exhibited a significantly enhanced absorbance response on a novel ELISA for anti-melanin antibodies, compared to sera from age-matched control subjects. The enhanced ELISA absorbance response was specific for catecholamine-based melanins and was unrelated to antiparkinsonian dopaminergic medication. Further, the absorbance response was significantly and negatively correlated with disease duration. These data suggest that a specific humoral anti-melanin antibody response is present in PD and is more active in early disease. While the contribution of this novel immune response to the initiation and progression of this disorder is unclear, this finding supports the hypothesis that specific immune responses occurring in PD may respond to therapeutic interventions in this disorder.

Tyrosinase is not detected in human catecholaminergic neurons by immunohistochemistry and Western blot analysis

Catecholaminergic neurons of the primate substantia nigra (SN) pars compacta (SNc) and the locus coeruleus contain neuromelanin (NM) granules as characteristic structures underlying the pigmentation of these brain areas. Due to a phylogenetic appearance NM granules are absent in the rodent brain, but gradually become present in primates until they reach a maximal expression in humans. Although a possible mechanism of pigment formation may be autoxidation of the NM precursors dopamine or noradrenalin, several groups have suggested an enzymatic formation of NM mediated by tyrosinase or a related enzyme. Since tyrosinase mRNA is suggested to be expressed in the SN of mice and humans, we reinvestigated the expression of tyrosinase in the human SNc and the locus coeruleus at the protein level by immunohistochemistry and Western blot analysis, but could not detect tyrosinase in these brain regions.

Therapeutic drug monitoring of quetiapine in adolescents with psychotic disorders

INTRODUCTION

There are developmental and age-dependent differences in the pharmacokinetics and the pharmacodynamics of drugs in children and adolescents. Therefore, there is a need to carry out standardised studies to find out therapeutic ranges of plasma/serum concentrations in psychopharmacotherapy of children and adolescents. The aim of this prospective study was to examine the relationship between quetiapine serum concentration, treatment response, and side effects in a clinical setting to elucidate the age-specific therapeutic range of quetiapine in adolescents.

METHODS

Over a period of two years, therapeutic drug monitoring (TDM) was routinely performed in 21 adolescents (mean age was 15.9+/-1.5 years, 57% male) with psychotic disorders according to the guidelines of the AGNP TDM expert group. The psychopathology was assessed by using the Clinical Global Impression Scale (CGI) and the Brief Psychiatric Rating Scale (BPRS). Side effects were assessed by using the Dose Record and Treatment Emergent Symptom Scale (DOTES). Trough quetiapine concentrations were determined under steady state conditions after multiple-dose regimes (median 600 mg/day; range 100-800 mg/day).

RESULTS

There was a marked variability of the serum concentrations, ranging from 19-877 ng/ml. 40.8% of the determined values were below and 24.5% above the therapeutic range (70-170 ng/ml) recommended for adults. None of the patients had severe side effects. We found a weak correlation between dose and serum concentration of quetiapine and no relationship between serum concentration and treatment response.

DISCUSSION

There are several limitations of this study, and our results should therefore be interpreted with caution. Notwithstanding, differences in the ontogenesis of pharmacokinetics and pharmacodynamics may be the reason for the difference in the relationship between blood concentrations and therapeutic response to psychopharmaca in children, adolescents and adults. Further studies using larger samples, baseline assessment of psychopathology, definition of the treatment interval and investigation of clinically relevant interactions with various co-medications are warranted to improve the limitations of this pilot study.

Dopaminergic dysbalance in distinct basal ganglia neurocircuits: implications for the pathophysiology of Parkinson's disease, schizophrenia and attention deficit hyperactivity disorder

The basal ganglia form a forebrain system that collects signals from a large part of the neocortex, redistributes these cortical inputs both with respect to one another and with respect to inputs from the limbic system, and then focuses the inputs of this redistributed, integrated signals into particular regions of the frontal lobes and brainstem involved in aspects of motor planning and motor memory. Movement disorders associated with basal ganglia dysfunction comprise a spectrum of abnormalities that range from the hypokinetic disorder (from which Parkinson's disease, PD, is the best-known-example) at one extreme to the hyperkinetic disorder (exemplified by Huntington's disease and hemiballism) at the other. In addition to disorders of movement, major mental disorders including schizophrenic-like states and attention deficit hyperactivity disorder (ADHD) have been linked to abnormalities in the basal ganglia and their allied nuclei. In this paper we discuss recent evidence indicating that a dopamine-induced dysbalance of basal ganglia neurocircuitries may be an important pathophysiological component in PD, schizophrenia and ADHD. According to our model, the deprivation of dopaminergic nigro-striatal input, as in PD, reduces the positive feedback via the direct system, and increases the negative feedback via the indirect system. The critical consequences are an overactivity of the basal ganglia output sites with the resulting inhibition of thalamo-cortical drive. In schizophrenia the serious cognitive deficits might be partly a result of a hyperactivity of the inhibitory dopamine D(2) transmission system. Through this dysinhibition, the thalamus exhibits hyperactivity that overstimulates the cortex resulting in dysfunctions of perception, attention, stimulus distinction, information processing and affective regulation (inducing hallucinations and delusions) and motor disabilities. Recent studies have strongly suggested that a disturbance of the dopaminergic system is also involved in the pathophysiology of ADHD. The most convincing evidence comes from the demonstration of the efficacy of psychostimulants such as the dopamine transporter (DAT) blocker methylphenidate in the symptomatic treatment of ADHD. Genetic studies have shown an association between ADHD and genes involved in dopaminergic neurotransmission (for example the dopamine receptor genes DRD4 and DRD5, and the DAT gene DAT1). DAT knockout mice display a phenotype with increased locomotor activity, which is normalized by psychostimulant treatment. Finally, imaging studies demonstrated an increased density of DAT in the striatum of ADHD patients. Which system is disturbed and whether this system is hyper- or hypoactive is not unambiguously known yet.

Therapeutic drug monitoring of tricyclic antidepressants in everyday clinical practice

Data about therapeutic drug monitoring (TDM) of psychotropic medications are often obtained from samples of highly selected individuals, who may not be representative for the average psychiatric patient. These data therefore may have limitations with regard to their transferability to everyday clinical practice. Therefore studies under naturalistic conditions are important to clarify the full clinical relevance of TDM. We retrospectively evaluated all TDM-analyses of the tricyclic antidepressants (TCA) amitriptyline and clomipramine during a 12-month period in an unselected sample of patients in a standard clinical setting. We especially examined the relationship between serum levels on one hand and clinical response and adverse effects on the other hand. In patients with amitriptyline, responders showed a significantly higher serum level than non-responders, whereas in patients with clomipramine a serum level within the recommended therapeutic range was associated with clinical response. We also found significantly higher serum concentrations in patients with adverse effects compared to patients without adverse effects in the clomipramine group. No such relationship could be shown in patients treated with amitriptyline. Our results suggest that therapeutic ranges in naturalistic settings in some ways differ from those obtained in controlled clinical settings and that TDM studies in everyday clinical practice are necessary and beneficial.

Association of Parkinson's disease with symptoms of attention deficit hyperactivity disorder in childhood

Methylphenidate (MPH) is a centrally acting (psycho)stimulant which reversibly blocks the dopamine re-uptake transporter. At present MPH is one of the most frequently prescribed drugs for the symptomatic treatment of attention deficit hyperactivity disorder (ADHD). Although MPH has been in use for about 50 years, there is no information available concerning the long-term benefits and risks of medication. Based on experiments in rats it has been suggested that MPH treatment may affect the maturation of central dopaminergic systems and may be a risk factor for the development of Parkinson's disease (PD). The aim of the present case-control study was to gain information about (1) ADHD-like symptoms that may precede PD motor symptoms, and (2) the exposure to psychostimulants in childhood. We used a German short version of the Wender Utah Rating Scale (WURS-k, Retz-Junginger et al., 2002) which is a reliable measure for the retrospective diagnosis of childhood ADHD, and another questionnaire including a rating scale for symptoms of ADHD in childhood (Q-ADHD-Child) according to DSM-IV and ICD-10 criteria. A total of 92 patients with PD and 115 control subjects were enrolled in this study. Ninety-six percentage of PD patients (N = 88) completed the two rating scales. The data of these patients and of 88 randomly selected individuals of the controls were included for analysis. In the WURS-k, the PD group showed higher total scores compared to control subjects. In addition, we found increased scores in PD patients regarding the items attention deficit, hyperactivity and anxious and depressive symptoms, but not regarding impulsivity, oppositional behaviour and deficits in social adaptation. The results of the Q-ADHD-Child also showed increased scores in PD patients regarding attention deficit and hyperactivity. However, one cannot conclude that the PD patients enrolled in this study had suffered from childhood ADHD, since the average total WURS-k score of (14.4) was far below the cut-off score of 30 or higher which is considered to identify childhood ADHD. Finally, we found no evidence that PD patients had been exposed to psychostimulants such as MPH and amphetamine.

Interaction of attention and graphomotor functions in children with attention deficit hyperactivity disorder

The present article provides a review of a series of studies in children with attention deficit hyperactivity disorder (ADHD) concerning (1) the effects of methylphenidate on various attentional functions, (2) the stimulant-induced changes of both qualitative and quantitative (i.e. kinematic) aspects of handwriting, (3) the interaction between conscious control of handwriting and fluency of handwriting movements, and (4) possible therapeutic approaches to graphomotor disturbances. Children with ADHD showed impairments in various aspects of attentional functioning. Pharmacological treatment of ADHD children with methylphenidate resulted in marked improvements of various components of attentional functioning. In comparison to the performance following the withdrawal of methylphenidate, children with ADHD on methylphenidate displayed a significant improvement in task accuracy in the areas of vigilance, divided attention, selective attention (inhibition, focused attention and integration of sensory information) and flexibility. However, the comparison with healthy children revealed considerable deficits regarding vigilance, divided attention, flexibility and selective attention (focused attention and integration of sensory information) in children with ADHD on methylphenidate. The comparison of writing movements of children on and off methylphenidate revealed that medication resulted in a better handwriting, but a deterioration in handwriting fluency as assessed by kinematic analysis. Children with ADHD may use their increased attentional capacities to focus on skills (e.g. handwriting) that are independent of conscious control or may even be disturbed by attention. The findings summarized in this paper indicate, therefore, that administration of methylphenidate alone is insufficient in the treatment of children with ADHD. Children with ADHD may benefit from instructions on how to best use their improved attentional capacities.

Behavioural and expressional phenotyping of nitric oxide synthase-I knockdown animals

The gaseous messenger nitric oxide (NO) has been implicated in a wide range of behaviors, including aggression, anxiety, depression, and cognitive functioning. To further elucidate the physiological role of NO and its down-stream mechanisms, we conducted behavioral and expressional phenotyping of mice lacking the neuronal isoform of nitric oxide synthase (NOS-I), the major source of NO in the central nervous system. No differences were observed in activity-related parameters; in contrast to the a priori hypothesis, derived from pharmacological treatments, depression-related tests (Forced Swim Test, Learned Helplessness) also yielded no significantly different results. A subtle anxiolytic phenotype however was present, with knockdown mice displaying a higher open arm time as compared to their respective wildtypes, yet all other investigated anxiety-related parameters were unchanged. The most prominent feature however was gender-independent cognitive impairment in spatial learning and memory, as assessed by the Water Maze test and an automatized holeboard paradigm. No significant dysregulation of monoamine transporters was evidenced by qRT PCR. To further examine the underlying molecular mechanisms, the transcriptome of knockdown animals was thus examined in the hippocampus, striatum and cerebellum by microarray analysis. A set of >120 differentially expressed genes was identified, whereat the hippocampus and the striatum showed similar expressional profiles as compared to the cerebellum in hierarchical clustering. Among the most significantly up-regulated genes were Peroxiredoxon 3, Atonal homologue 1, Kcnj1, Kcnj8, CCAAT/enhancer binding protein (C/EBP), alpha, 3 genes involved in GABA(B) signalling and, intriguingly, the glucocorticoid receptor GR. While GABAergic genes might underlie reduced anxiety, dysregulation of the glucocorticoid receptor can well contribute to a blunted stress response as found in NOS1 knockdown mice. Furthermore, by CREB inhibition, glucocorticoid receptor upregulation could at least partially explain cognitive deficits in these animals. Taken together, NOS1 knockdown mice display a characteristic behavioural profile consisting of reduced anxiety and impaired learning and memory, paralleled by differential expression of the glucocorticoid receptor and GABAergic genes. Further research has to assess the value of these mice as animal models e.g. for Alzheimer's disease or attention deficit disorder, in order to clarify a possible pathophysiological role of NO therein.

Measurement of the x-ray mass energy-absorption coefficient of air using 3 keV to 10 keV synchrotron radiation

For the first time absolute photon mass energy-absorption coefficients of air in the energy range 3 keV to 10 keV have been measured with relative standard uncertainties less than 1%, significantly smaller than those of up to 5% assumed hitherto for calculated data. Monochromatized synchrotron radiation was used to measure both the total radiant energy by means of silicon photodiodes calibrated against a cryogenic radiometer and the fraction of radiant energy that is deposited in dry air by means of a free air ionization chamber. The measured ionization charge was converted into energy absorbed in air by calculated effective W values of photons as a function of their energy based on new measurements of the W values in dry air for electron kinetic energies between 1 keV and 7 keV, also presented in this work. The measured absorption coefficients were compared with state-of-the art calculations and found to agree within 0.7% with data calculated earlier by Hubbell at energies above 4 keV but were found to differ by values up to 2.1% at 10 keV from more recent calculations of Seltzer.

Proteomics of the human brain: sub-proteomes might hold the key to handle brain complexity

Proteomics is a promising approach, which provides information about the expression of proteins and increasingly finds application in life science and disease research. Meanwhile, proteomics has proven to be applicable even on post mortem human brain tissue and has opened a new area in neuroproteomics. Thereby, neuroproteomics is usually employed to generate large protein profiles of brain tissue, which mostly reflect the expression of highly abundant proteins. As a complementary approach, the focus on sub-proteomes would enhance more specific insight into brain function. Sub-proteomes are accessible via several strategies, including affinity pull-down approaches, immunoprecipitation or subcellular fractionation. The extraordinary potential of subcellular proteomics to reveal even minute differences in the protein constitution of related cellular organelles is exemplified by a recent global description of neuromelanin granules from the human brain, which could be identified as pigmented lysosome-related organelles.

Investigation of the lipid component of neuromelanin

OBJECTIVE

Neuromelanin (NM) is different to other melanins in that its ultrastructure includes a lipid component. The objectives of this study were to identify and quantify lipids associated with NM.

RESULTS

Quantification of the lipid component associated with the pigment on electron micrographs demonstrated that this component comprises 35% of the NM granule volume in the normal brain. The irregular ultrastructural appearance of the NM granules was quite different to the round regular boundary of melanin granules. Using reversed phase high performance liquid chromatography (HPLC) coupled with atmospheric pressure chemical ionization (APCI) mass spectrometry we demonstrated that the isoprenoid dolichol accounted for approximately 12% of total NM pigment mass. Low levels of other lipids were detectable (cholesterol, ubiquinone-10 and alpha-tocopherol) and account for <0.05% of NM lipid, in contrast to cholesterol accounting for 35% of total brain lipids.

CONCLUSION

Unlike other melanins, a substantial proportion of NM volume is comprised of lipid and the major type of lipid associated with NM granules is the isoprenoid dolichol.

Structural investigations of neuromelanin by pyrolysis-gas chromatography/mass spectrometry

Pyrolysis combined with gas chromatography and mass spectrometry (Py-GC/MS) was applied for structural investigations of the human substantia nigra neuromelanin. Using synthetic neuromelanins, we have demonstrated that Py-GC/MS is suitable for identification and differentiation of both eumelanin (dopamine-derived) and pheomelanin (cysteinyldopamine-derived) component of the pigment. Structural information on melanin monomers was inferred from their pyrolytic markers. When the human neuromelanin was subjected to pyrolysis, none of the heterocyclic, sulfur-containing markers of pheomelanin component was detected among the thermal degradation products. We have concluded that nigral pigment isolated from normal brain tissue does not contain benzothiazine-type monomers, and that cysteinyldopamine-originated units may be incorporated into the polymer in uncyclized form. The most abundant pyrolysis product was identified as limonene, which indicates that nigral pigment is tightly associated with an isoprenoid-type compound. Pyrolysis in the presence of the methylating reagent allowed identification of high levels of saturated and monounsaturated straight-chain C14-C18 fatty acid species chemically bound to the pigment macromolecule.

Subcellular proteomics reveals neuromelanin granules to be a lysosome-related organelle

The powerful combination of subcellular fractionation and protein identification by electrospray ionization tandem mass spectrometry (ESI-MS/MS) pioneered the molecular elucidation of neuromelanin (NM) granules. We recently isolated NM granules from the human brain and succeeded in the establishment of the first protein profile of this compartment. NM granules are pigmented organelles, which are mainly found in the catecholaminergic neurons of the human substantia nigra (SN) pars compacta and the locus coeruleus. These granules contain the insoluble pigment NM, which is regarded as the most important iron storage system in these neurons. A global examination of NM granules, however, has so far been hampered due to the lack of a pigmented brain stem in rodents, the absence of an appropriate experimental system and their scarcity in the human brain. 'Subcellular proteomics', which increasingly emerges as the method of choice to characterize cellular compartments and to elucidate their biogenesis, has recently been shown to be an adequate approach to tackle a thorough description of NM granules. Thereby, NM granules could be described as a 'lysosome-related organelle'. This indicates a genetic program underlying a biogenesis of NM rather than its autoxidative formation.

Evidence for specific phases in the development of human neuromelanin

Neuromelanin is a dark-coloured pigment which forms in the dopamine neurons of the human midbrain. The age-related development and regulation of neuromelanin within these dopamine neurons has not been previously described. Optical density and area measurements of unstained neuromelanin in ventral substantia nigra neurons from 29 people spanning the ages of 24 weeks to 95 years old, demonstrated three developmental phases. Neuromelanin was not present at birth and initiation of pigmentation began at approximately 3 years of age, followed by a period of increasing pigment granule number and increasing pigment granule colouration until age 20. In middle and later life the colour of the pigment granules continued to darken but was not associated with any substantial growth in pigment volume. The identification of three phases and changes in the rate of neuromelanin production over time suggests the regulation of neuromelanin production and turnover, possibly through enzymatic processes.

Evidence for specific phases in the development of human neuromelanin

Neuromelanin is a dark-coloured pigment which forms in the dopamine neurons of the human midbrain. Here we describe the age-related development and regulation of neuromelanin within these dopamine neurons. 10 microm sections from formalin-fixed midbrain from 29 people spanning the ages of 24 weeks to 95 years old were either stained with a basic Nissl substance stain (0.5% cresyl violet), or processed unstained. After locating the substantia nigra using the stained sections, digital photos were taken of individual ventral substantia nigra neurons in the unstained sections, and the cellular area occupied by pigment, and optical density were measured using computer software. These measurements demonstrated three developmental phases. Neuromelanin was not present at birth and initiation of pigmentation began at approximately 3 years of age, followed by a period of increasing pigment granule number and increasing pigment granule colouration until age 20. In middle and later life the colour of the pigment granules continued to darken but was not associated with any substantial growth in pigment volume. The identification of three phases and changes in the rate of neuromelanin production over time suggests the regulation of neuromelanin production and turnover, possibly through enzymatic processes.

Microarray analysis reveals distinct gene expression patterns in the mouse cortex following chronic neuroleptic and stimulant treatment: implications for body weight changes

Atypical neuroleptics are associated with clinical significant weight gain, whereas stimulants are used as anorexiant drugs. The aim of this study was to examine gene expression changes in the mouse frontal cortex following chronic oral treatment with antipsychotics and a stimulant by microarray assessments. Twenty 10-12-week-old male C57BL6 mice received daily for 31 days either the typical neuroleptic haloperidol (1 mg/kg), the atypical neuroleptic clozapine (10 mg/kg) or the stimulant phenylpropanolamine (3 mg/kg). We identified a set of genes that was differently expressed between the neuroleptic-treated groups and the stimulant-treated group. Importantly, we found in the majority of gene alterations down-regulation in genes involved in ATP biosynthesis and lipid metabolism following the stimulant treatment, suggesting these genes as candidates that may regulate body weight. We also identified remarkable expression patterns of genes that encode signalling molecules (e.g. insulin, mitochondrial uncoupling protein 1) that are implicated in the control of food intake and are differently expressed in the neuroleptic groups.

Apoptosis inhibition in T cells triggers the expression of proinflammatory cytokines--implications for the CNS

Stimulation of death receptors such as CD95 or TNF-R1 results in rapid onset of apoptosis. Here we show that inhibition of death receptor-induced apoptosis by the broad range caspase inhibitor ZVAD causes a switch from apoptotic to proinflammatory signaling. In previous studies we have reported that caspase inhibitors induce expression of various proinflammatory cytokines in CD95-stimulated primary T cells, such as TNF-alpha, IFN-gamma and GM-CSF. In this study we provide further evidence for the proinflammatory activity of CD95. Stimulation of CD95 by agonistic antibodies (7C11) resulted in expression of IL-2 in primary T cells, which was further enhanced when caspase activity was blocked by ZVAD. Moreover, CD95 triggered expression of IL-4 and IL-8 when caspase activity was inhibited, but not in the absence of ZVAD. Our findings are of significant importance for the CNS as changes in the cytokine pattern in the periphery affects the entry of various immune cells into the brain. Moreover, invading activated T cells can also directly influence the cytokine profile within the brain, triggering signaling cascades that eventually lead to neuronal cell death. The use of caspase inhibitors to prevent apoptotic cell death should be carefully evaluated in the management of systemic and CNS diseases.

Potential sources of increased iron in the substantia nigra of parkinsonian patients

Histopathological, biochemical and in vivo brain imaging techniques, such as magnetic resonance imaging and transcranial sonography, revealed a consistent increase of substantia nigra (SN) iron in Parkinson's disease (PD). Increased iron deposits in the SN may have genetic and non-genetic causes. There are several rare movement disorders associated with neurodegeneration, and genetic abnormalities in iron regulation resulting in iron deposition in the brain. Non-genetic causes of increased SN iron may be the result of a disturbed or open blood-brain-barrier, local changes in the normal iron-regulatory systems, intraneuronal transportation of iron from iron-rich area into the SN and release of iron from intracellular iron storage molecules. Major iron stores are ferritin and haemosiderin in glial cells as well as neuromelanin in neurons. Age- and disease dependent overload of iron storage proteins may result in iron release upon reduction. Consequently, the low molecular weight chelatable iron complexes may trigger redox reactions leading to damage of biomolecules. Additionally, upon neurodegeneration there is strong microglial activation which can be another source of high iron concentrations in the brain.

Neuromelanin induces oxidative stress in mitochondria through release of iron: mechanism behind the inhibition of 26S proteasome

Parkinson's disease is characterized by the selective depletion of dopamine neurons in the substantia nigra, particular those containing neuromelanin. Involvement of neuromelanin in the pathogenesis may be either cytotoxic or protective. Recently we found that neuromelanin reduces the activity of 26S proteasome. In this paper, the detailed mechanisms behind the reduced activity were studied using neuromelanin isolated from the human brain. Neuromelanin increased the oxidative stress, but synthetic melanin did not. Superoxide dismutase and deferoxamine completely suppressed the increase, indicating that superoxide produced by an iron-mediated reaction plays a central role. Iron was shown to reduce in situ 26S proteasome activity in SH-SY5Y cells and the reduction was protected by antioxidants. These results suggest that iron released from neuromelanin increases oxidative stress in mitochondria, and then causes mitochondrial dysfunction and reduces proteasome function. The role of neuromelanin is discussed in relation to the selective vulnerability of dopamine neurons in Parkinson's disease.

Neuromelanin in human dopamine neurons: comparison with peripheral melanins and relevance to Parkinson's disease

Neuromelanin (NM) is a dark polymer pigment produced in specific populations of catecholaminergic neurons in the brain. It appears in greatest quantities in the human brain, in lesser amounts in some other non-human primates, but is absent from the brain in many lower species. Interest in this pigment has seen a resurgence in recent years because of a hypothesised link between neuromelanin and the especial vulnerability of neuromelanin-containing neurons to cell death in Parkinson's disease (PD). Little is known regarding the biology of neuromelanin. As neuromelanin appears to have characteristics in common with the better studied peripheral melanin pigments this review compares what is known about neuromelanin with melanins found in other body tissues. Unlike peripheral melanins, which are produced in specialised cells called melanocytes and may be transferred to other cell types, neuromelanin granules are believed to be stored in the cell in which they are produced. Neuromelanin granules display a unique, more heterogeneous appearance compared with peripheral melanins. Unlike melanin, neuromelanin is traditionally thought to result from a non-enzymatic synthesis pathway with no known pathway for neuromelanin catabolism. More recent data, however, is indicative of some regulation of neuromelanin synthesis and turnover. By analogy with peripheral melanins, neuromelanin may function in vivo to attenuate the effects of damaging stimuli. Among several possible mechanisms suggested, the ability of neuromelanin to interact with transition metals, especially iron, and to mediate intracellular oxidative mechanisms has received particular attention. Recent data from neuromelanin in the Parkinson's disease brain suggests that this proposed function may be compromised, thus rendering pigmented neurons vulnerable to oxidative damage in this disorder.