Biomedical subjects

Steven G Potkin

Publications and source records attributed to Steven G Potkin.

At least 19 recordsLinked to original sources

PubMed2007

Effect of acetylcholinesterase inhibitors on the binding of nicotinic alpha4beta2 receptor PET radiotracer, (18)F-nifene: A measure of acetylcholine competition.

Acetylcholinesterase inhibitors (AChEI's) are used to treat Alzheimer's disease (AD), and the putative mode of action is to increase acetylcholine (ACh) levels. Our goal is to evaluate competition of ACh with nicotinic alpha4beta2 receptor PET agonist radiotracer, 2-[(18)F]fluoro-3-[2-((S)-3-pyrrolinyl)methoxy]pyridine ((18)F-nifene). This ability to measure ACh-(18)F-nifene competition may have potential to assess efficacy of AChEI's in vivo. In vitro studies in rat brain slices used two AChEI's, physostigmine (PHY) and galanthamine (GAL). Brain slices were incubated with (18)F-nifene and various concentrations of PHY (0.2-20 microM) or GAL (0.4-4 microM) prior to (18)F-nifene treatment. For ACh competition, slices were also incubated with PHY + 100 nM ACh or GAL + 100 nM ACh or 100 nM ACh alone. Nonspecific binding of (18)F-nifene was determined using 300 microM nicotine. In the in vitro rat brain homogenate binding assay, ACh inhibited (3)H-cytisine binding to alpha4beta2 receptors with K(i) values of 19.2 nM (with PHY) and 34.7 microM (no PHY) indicating approximately 1.8 x 10(3) weaker binding of ACh in the absence of AChEI. Binding of (18)F-nifene was not affected by PHY (0.2-20 microM) or ACh 100 nM alone but decreased substantially by PHY + ACh 100 nM in all brain regions (down by >40% of control in thalamus). Similarly, for GAL (4 microM) no effect on (18)F-nifene binding occurred but GAL (0.4-4 microM) + ACh 100 nM showed a reduction of (18)F-nifene binding in all brain regions (down by approximately 15%). The reduction in both cases is a result of ACh competition with (18)F-nifene in the presence of AChEI. These preliminary in vitro results suggest that ACh is able to compete with (18)F-nifene at the alpha4beta2 receptors in the presence of PHY or GAL. The effect is AChEI-concentration dependent and is greater for PHY than GAL. Thus (18)F-nifene has promise for assessing ACh levels and AChEI effects in vivo.

Acetylcholine↗

PubMed2006

Association study of four dopamine D1 receptor gene polymorphisms and clozapine treatment response.

Dopamine D1 receptors (D1) in the prefrontal cortex have been implicated in the modulation of cognitive processes as well as both positive and negative symptoms of schizophrenia. Therefore pharmacologic agents with potent D1 effects such as clozapine may influence the symptoms of schizophrenia (SCZ). Genetic variation in the D1 receptor gene (DRD1) may help to explain some of the variability in patient response to antipsychotics (APs). This study investigates the effect of four single nucleotide polymorphisms (SNPs) in DRD1 on clozapine response in two distinct SCZ populations (Caucasian and African American) refractory or intolerant to conventional APs. This study included 183 Caucasian and 49 African American schizophrenics diagnosed using the Diagnostic and Statistical Manual of Mental Disorders (revised third or fourth edition). Genotyping was determined by 5'-exonuclease fluorescence assays. Within each population genotype, allele, allele +/- and haplotype frequencies were compared against dichotomous and quantitative measures of treatment response. Linkage disequilibrium analysis was also performed. In the Caucasian sample, no associations were observed for individual SNP tests. However, a rare three-marker haplotype predicted poor response. In the African American sample, the rs265976 variant and another three-marker haplotype were associated with cLozapine response. Although we did not find an association between the rs4532 SNP (-48 A/G, recognized by a DdeI restriction cut site) and cLozapine response as reported by Potkin et al. (2003), a trend in the same direction was observed as well. Our findings suggest that the rs4532 SNP may have a small effect if any. Further studies in larger, independent samples are required to validate these findings.

Adult↗

PubMed2006

Association study of tardive dyskinesia and twelve DRD2 polymorphisms in schizophrenia patients.

Tardive dyskinesia (TD) is a side-effect of chronic antipsychotic medication. Abnormalities in dopaminergic activity in the nigrostriatal system have been most often suggested to be involved because the agents which cause TD share in common potent antagonism of dopamine D2 receptors (DRD2), that notably is not balanced by effects such as more potent serotonin (5-HT)2A antagonism. Thus, a number of studies have focused on the association of dopamine system gene polymorphisms and TD. The most consistent findings have been found with the Ser9Gly polymorphism of the DRD3 gene. Although DRD2 has long been hypothesized to be the main target for antipsychotics, only a few polymorphisms in DRD2 have been investigated for their potential involvement in the aetiology of TD. In the present study, we investigated 12 polymorphisms spanning the DRD2 gene and their association with TD in our European Caucasian (n=202) and African-American (n=30) samples. Genotype frequencies for a functional polymorphism, C957T (Duan et al., 2003; Hirvonen et al., 2004), and the adjacent C939T polymorphism were found to be significantly associated with TD (p=0.013 and p=0.022 respectively). DRD2 genotypes were not significantly associated with TD severity as measured by AIMS (Abnormal Involuntary Movement Scale) with the exception of a trend for C939T (p=0.071). Both TD and total AIMS scores were found to be significantly associated with two-marker haplotypes containing C939T and C957T (p=0.021 and p=0.0087 respectively). Preliminary results indicated that C957T was also associated with TD in our African-American sample (p=0.047). Taken together, the present study suggests that DRD2 may be involved in TD in the Caucasian population, although further studies are warranted.

Adult↗

PubMed2006

A double-blind comparison of risperidone, quetiapine and placebo in patients with schizophrenia experiencing an acute exacerbation requiring hospitalization.

OBJECTIVE: This study compared the effects of atypical antipsychotics (risperidone or quetiapine) with placebo and with each other in recently exacerbated patients with schizophrenia requiring hospitalization. METHODS: This international, randomized, double-blind study included a 2-week monotherapy phase followed by a 4-week additive therapy phase. Recently exacerbated patients with schizophrenia or schizoaffective disorder (DSM-IV) were randomized (2:2:1) to risperidone (n = 153), quetiapine (n = 156), or placebo (n = 73). Target doses were 4 or 6 mg/day of risperidone and 400 or 600 mg/day of quetiapine by day 5, with the ability to increase to 600 or 800 mg/day of quetiapine on day 8. The main outcome measures were the total Positive and Negative Syndrome Scale (PANSS) and need for additional psychotropic medications. RESULTS: Monotherapy Phase: The combined atypical antipsychotic group (n = 308) reached borderline superiority to placebo (n = 71) at the 2-week endpoint on mean change in total PANSS score (-24.1 +/- 1.2 and -20.2 +/- 2.0, respectively; p = 0.067). The change in the atypical group was driven by the improvement with risperidone (-27.7 +/- 1.5 vs. -20.2 +/- 2.0 with placebo, p < 0.01; and vs. -20.5 +/- 1.5 with quetiapine, p < 0.01); the improvement with quetiapine was similar to placebo, p = 0.879. Results were similar on other efficacy endpoints. Additive Therapy Phase: Additional psychotropics were prescribed to fewer (p < 0.01) risperidone (36%) than quetiapine (53%) or placebo patients (59%). The overall discontinuation rate was 18%, 26%, and 38%, respectively. Risperidone, compared with placebo, was associated with more parkinsonism, akathisia, plasma prolactin changes, and weight gain; while quetiapine was associated with more somnolence, sedation, dizziness, constipation, tachycardia, thyroid dysregulation, and weight gain. CONCLUSION: While the combined atypical antipsychotic group did not experience greater improvements than the placebo group, risperidone, but not quetiapine, was significantly superior in all measured domains to placebo in the management of recently exacerbated hospitalized patients with schizophrenia or schizoaffective disorder, with no unexpected tolerability findings.

Acute Disease↗

PubMed2006

Nicotinic alpha4beta2 receptor imaging agents: part II. Synthesis and biological evaluation of 2-[18F]fluoro-3-[2-((S)-3-pyrrolinyl)methoxy]pyridine (18F-nifene) in rodents and imaging by PET in nonhuman primate.

The alpha4beta2 nicotinic acetylcholine receptor (nAChR) has been implicated in various neurodegenerative diseases. Optimal positron emission tomography (PET) imaging agents are therefore highly desired for this receptor. We report here the development and initial evaluation of 2-fluoro-3-[2-((S)-3-pyrrolinyl)methoxy]pyridine (nifene). In vitro binding affinity of nifene in rat brain homogenate using 3H-cytisine exhibited a K(i) = 0.50 nM for the alpha4beta2 sites. The radiosynthesis of 2-18F-fluoro-3-[2-((S)-3-pyrrolinyl)methoxy]pyridine (18F-nifene) was accomplished in 2.5 h with an overall radiochemical yield of 40-50%, decay corrected. The specific activity was estimated to be approx. 37-185 GBq/micromol. In vitro autoradiography in rat brain slices indicated selective binding of 18F-nifene to anteroventral thalamic (AVT) nucleus, thalamus, subiculum, striata, cortex and other regions consistent with alpha4beta2 receptor distribution. Rat cerebellum showed some binding, whereas regions in the hippocampus had the lowest binding. The highest ratio of >13 between AVT and cerebellum was measured for 18F-nifene in rat brain slices. The specific binding was reduced (>95%) by 300 microM nicotine in these brain regions. Positron emission tomography imaging study of 18F-nifene (130 MBq) in anesthetized rhesus monkey was carried out using an ECAT EXACT HR+ scanner. PET study showed selective maximal uptake in the regions of the anterior medial thalamus, ventro-lateral thalamus, lateral geniculate, cingulate gyrus, temporal cortex including the subiculum. The cerebellum in the monkeys showed lower binding than the other regions. Thalamus-to-cerebellum ratio peaked at 30-35 min postinjection to a value of 2.2 and subsequently reduced. The faster binding profile of 18F-nifene indicates promise as a PET imaging agent and thus needs further evaluation.

Animals↗

PubMed2006

Alpha EEG predicts visual reaction time.

Studies have suggested that consciousness is encoded discretely in time and synchronously in space of the brain. The present study was to model the alpha EEG as a brain clock to carry out the functions and to test whether the quality and rate of the oscillation could predict behavioral timing. Results showed that the alpha peak frequency was correlated with the conflict reaction time, and the selectivity was associated with the simple reaction time. These findings are consistent with previous reports and support the hypothesis that alpha EEG represents excitability cycles and may serves as a brain clock for spatial synchronization.

Adult↗

PubMed2006

Memantine treatment in mild to moderate Alzheimer disease: a 24-week randomized, controlled trial.

OBJECTIVE: The objective of this study was to compare the efficacy and safety of the moderate-affinity, uncompetitive N-methyl-d-aspartate receptor antagonist, memantine, versus placebo in patients with mild to moderate Alzheimer disease (AD). METHOD: This was a randomized, double-blind, placebo-controlled clinical trial conducted at 42 U.S. sites. Participants were 403 outpatients with mild to moderate AD and Mini-Mental State Examination scores of 10-22 randomized to memantine (20 mg/day; N=201) or placebo (N=202) for 24 weeks. Primary outcomes were change from baseline at 24 weeks on the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog), a measure of cognition, and on the Clinician's Interview-Based Impression of Change Plus Caregiver Input (CIBIC-Plus), a global measure. Secondary outcomes included change on the Neuropsychiatric Inventory (NPI) and the Alzheimer's Disease Cooperative Study Activities of Daily Living Inventory (ADCS-ADL(23)), measures of behavior and function, respectively. RESULTS: Most (82.4%) participants completed the trial. Memantine resulted in significantly better outcomes than placebo on measures of cognition, global status, and behavior when based on the protocol-specified primary last observation carried forward imputation as well as a mixed-models repeated-measures approach applied to the continuous outcomes. Treatment discontinuations because of adverse events for memantine versus placebo were 19 (9.5%) and 10 (5.0%), respectively. CONCLUSIONS: These results support the safety and efficacy of memantine for the treatment of mild to moderate AD.

Aged↗

PubMed2006

Imaging phenotypes and genotypes in schizophrenia.

Schizophrenia is associated with subtle structural and functional brain abnormalities. Both recent and classical data suggest that it is a heterogeneous disorder that is clearly heritable. The cause and course of schizophrenia are poorly understood, and classical categories of clinical symptoms have not been particularly useful in identifying its pathophysiology or predicting its treatment. The possible genetic risk factors for schizophrenia are numerous; however, the connection between the genotype and the time-course, or the multifaceted symptoms of the disease, has yet to be established. Brain imaging methods that study the structure or function of the cortical and subcortical regions have also identified distinct patterns that distinguish schizophrenics from controls, and that may identify meaningful subtypes of schizophrenia. The predictive relationship between these imaging phenotypes and disease characteristics such as treatment response is only beginning to be revealed. The emergence of the field of imaging genetics, combining genetic, and neuroimaging data, holds much promise for the deeper understanding and improved treatment of diseases such as schizophrenia. In this article we review some of the key findings in imaging phenotyping and genotyping of schizophrenia, and the initial endeavors at their combination into more meaningful and predictive patterns, or endophenotypes identifying the relationships among clinical symptoms, course, genes, and the underlying pathophysiology.

Brain↗

PubMed2006

A general XML schema and SPM toolbox for storage of neuro-imaging results and anatomical labels.

With the increased frequency of multisite, large-scale collaborative neuro-imaging studies, the need for a general, self-documenting framework for the storage and retrieval of activation maps and anatomical labels becomes evident. To address this need, we have developed and extensible markup language (XML) schema and associated tools for the storage of neuro-imaging activation maps and anatomical labels. This schema, as part of the XML-based Clinical Experiment Data Exchange (XCEDE) schema, provides storage capabilities for analysis annotations, activation threshold parameters, and cluster and voxel-level statistics. Activation parameters contain information describing the threshold, degrees of freedom, FWHM smoothness, search volumes, voxel sizes, expected voxels per cluster, and expected number of clusters in the statistical map. Cluster and voxel statistics can be stored along with the coordinates, threshold, and anatomical label information. Multiple threshold types can be documented for a given cluster or voxel along with the uncorrected and corrected probability values. Multiple atlases can be used to generate anatomical labels and stored for each significant voxel or cluter. Additionally, a toolbox for Statistical Parametric Mapping software (http://www. fil. ion.ucl.ac.uk/spm/) was created to capture the results from activation maps using the XML schema that supports both SPM99 and SPM2 versions (http://nbirn.net/Resources/Users/ Applications/xcede/SPM_XMLTools.htm). Support for anatomical labeling is available via the Talairach Daemon (http://ric.uthscsa. edu/projects/talairachdaemon.html) and Automated Anatomical Labeling (http://www. cyceron.fr/freeware/).

Animals↗

PubMed2006

A pilot study evaluating the efficacy and safety of rivastigmine in patients with mixed dementia.

BACKGROUND AND OBJECTIVE: The two most common causes of dementia in the elderly are Alzheimer's disease (AD) and vascular dementia (VaD), which can coexist as mixed dementia. The object of this study was to assess the efficacy and safety of rivastigmine in patients with mixed dementia (AD with VaD). STUDY DESIGN: This 26-week open-label pilot study was conducted at 19 centres in the US. To reduce bias, the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-Cog) raters were blinded to all efficacy measures and to patient dosage information. Patients were treated with rivastigmine and titrated to their highest tolerated dose, up to 12 mg/day (6 mg twice daily). The primary efficacy measure was cognitive function assessed by the ADAS-Cog subscale (without the concentration/distractibility item, to be consistent with cognitive outcome measures used in previous rivastigmine trials). RESULTS: Forty-seven percent of patients treated with rivastigmine 6-12 mg/day demonstrated improvement on the ADAS-Cog at 26 weeks, with >25% of patients having a clinically significant improvement of > or =4 points. Treatment with rivastigmine (6-12 mg/day) was well tolerated by the majority of patients. The most common adverse effects occurring in >10% of patients were nausea, vomiting, dizziness and diarrhoea. CONCLUSION: This pilot study suggests that rivastigmine treatment may have beneficial effects in the treatment of patients with mixed dementia.

Adult↗

PubMed2006

Synthesis and biologic evaluation of a novel serotonin 5-HT1A receptor radioligand, 18F-labeled mefway, in rodents and imaging by PET in a nonhuman primate.

UNLABELLED: Serotonin 5-HT1A receptors have been implicated in disorders of the central nervous system and, therefore, are being studied by PET. Efforts are under way to improve in vivo stability of 5-HT1A agents currently in human use (11C-labeled N-(2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl-N-(2-pyridinyl)cyclohexanecarboxamide [11C-WAY-100635], 4-(2'-methoxyphenyl)-1-[2'-(N-2''-pyridinyl)-p-18F-fluorobenzamido]ethylpiperazine [18F-MPPF], and 18F-labeled trans-4-fluoro-N-(2-[4-(2-methoxyphenyl)piperazin-1-yl)ethyl]-N-(2-pyridyl)cyclohexanecarboxamide [18F-FCWAY]). We have synthesized N-{2-[4-(2-methoxyphenyl)piperazinyl]ethyl}-N-(2-pyridyl)-N-(4-18F-fluoromethylcyclohexane)carboxamide (18F-mefway), which contains a 18F on a primary carbon to make the compound more stable to defluorination. METHODS: Radiosynthesis of 18F-mefway was performed in a single tosylate for 18F-fluoride exchange. In vitro binding studies on rat brain slices using 18F-mefway were read on a phosphor imager. Monkey PET studies were performed on a whole-body PET scanner. RESULTS: Binding affinity (inhibitory concentration of 50% [IC50]) of mefway was 26 nmol/L and was comparable to that of WAY-100635, 23 nmol/L. Yields of 18F-mefway were 20%-30% in specific activities of 74-111 GBq/micromol at the end of synthesis. In vitro binding of 18F-mefway in the hippocampus (Hp), colliculus (Co), cortex (Ctx), and other brain regions-with limited binding in the cerebellum (Cer)--was observed, with ratios of Hp/Cer = 82.3, Co/Cer = 45.8, and Ctx/Cer = 40. Serotonin displaced 18F-mefway from various brain regions with IC50 values in the range of 169-243 nmol/L. PET studies in a rhesus monkey showed 18F-mefway binding in the fontal cortex (FC), temporal cortex (TC) including hippocampus, raphe (Rp), and other brain regions, with ratios of FC/Cer = 9.0, TC/Cer = 10, and Rp/Cer = 3.3. Plasma analysis indicated the presence of approximately 30% of 18F-mefway at 150-180 min after injection. CONCLUSION: The high ratios in specific brain regions such as the hippocampus suggest that 18F-mefway has potential as a PET agent for 5HT1A receptors.

Animals↗

PubMed2005

Association study between a functional glutathione S-transferase (GSTP1) gene polymorphism (Ile105Val) and tardive dyskinesia.

A possible role for oxidative stress in the pathophysiology of tardive dyskinesia (TD) has previously been proposed (reviewed in Andreassen and Jorgensen [O.A. Andreassen, H.A. Jorgensen, Neurotoxicity associated with neuroleptic-induced oral dyskinesias in rats Implications for tardive dyskinesia? Prog. Neurobiol. 61 (2000) 525-541]). Long-term administration of antipsychotics alters dopaminergic turnover, which results in increased formation of reactive oxygen species (ROS). This is hypothesized to lead to TD through neuronal toxicity as a consequence of oxidative stress. In the present study, the relationship between TD and a functional polymorphism of the gene coding for human glutathione S-transferase P1 (GSTP1), an important antioxidant enzyme involved in the detoxification of ROS, was studied in 225 chronic treatment-refractory patients with schizophrenia. An isoleucine (Ile) to valine (Val) substitution at codon 105 (Ile105Val) in the GSTP1 gene was genotyped. No significant difference in total AIMS scores was found among patients in the three genotype groups (chi(2)=1.47, d.f.=2, p=0.48). Moreover, no significant differences in genotype (chi(2)=0.05, d.f.=2, p=0.98) or allele frequencies (chi(2)=0.00, d.f.=1, p=1.00) were observed between subjects with and without TD. Our results suggest that the GSTP1 gene polymorphism does not confer increased susceptibility to TD, although further studies are warranted before a conclusion can be drawn.

Adolescent↗

PubMed2005

Therapeutic effects of individualized alpha frequency transcranial magnetic stimulation (alphaTMS) on the negative symptoms of schizophrenia.

Previous research in clinical electroencephalography (EEG) has demonstrated that reduction of alpha frequency (8-13 Hz) EEG activity may have particular relevance to the negative symptoms of schizophrenia. Repetitive Transcranial Magnetic Stimulation (rTMS) was utilized to investigate this relationship by assessing the therapeutic effects of stimulation set individually at each subject's peak alpha frequency (alphaTMS). Twenty-seven subjects, with predominantly negative symptom schizophrenia, received 2 weeks of daily treatment with either alphaTMS, 3 Hz, 20 Hz, or sham stimulation bilaterally over the dorsolateral prefrontal cortex. Individualized alphaTMS demonstrated a significantly larger (F (3,33) = 4.7, p = .007) therapeutic effect (29.6% reduction in negative symptoms) than the other 3 conditions (< 9%). Furthermore, these clinical improvements were found to be highly correlated (r = 0.86, p = .001) with increases (34%) in frontal alpha amplitude following alphaTMS. These results affirm that the resonant features of alpha frequency EEG play an important role in the pathophysiology of schizophrenia and merit further investigation as a particularly efficacious frequency for rTMS treatments.

Alpha Rhythm↗

PubMed2005

Psychometric evaluation of the Readiness for Discharge Questionnaire.

OBJECTIVE: The Readiness for Discharge Questionnaire (RDQ) was developed as an easy to use tool for assessing readiness for discharge, independent of socio-economic factors, for inpatients with schizophrenia. The psychometric properties of the RDQ are described. METHODS: The RDQ consists of 6 items assessing suicidality/homicidality, control of aggression/impulsivity, activities of daily living, medication-taking, delusions/hallucinations interfering with functioning and global status. A final yes/no question assesses readiness for discharge. Data derived from 3 studies (500 patients in 3 countries) were used in analyzing inter-rater and test-retest reliability, content and construct validity, and sensitivity to change. RESULTS: The inter-rater reliability was high for all items of the RDQ (reliability coefficients >0.9) and moderate to high for the readiness for discharge status (Session I: 84% agreement, kappa 0.39, polychoric correlation r=0.81; Session II: 89% agreement, kappa 0.63, polychoric correlation r=0.81. Test-retest reliability was also high for all items of the RDQ (reliability coefficients >0.9) and the readiness for discharge status (kappa=0.743; tetrachoric correlation r=0.819). Overall, 84% of the raters agreed (mean score=5.0 of possible 6.0) that the RDQ was useful in assessing a patient's readiness for discharge from the hospital. Evidence of good construct validity included significant correlations with PANSS total and factor scores, and a significant relationship with actual discharge. Significantly more patients with symptom improvement were judged ready for discharge (compared to those without symptom improvement), indicating that the RDQ was sensitive to change over time. CONCLUSIONS: The RDQ has favorable reliability and validity properties, and is an easy to use instrument in research studies for assessing readiness for discharge of inpatients with schizophrenia. Additional work in naturalistic settings is required to further validate the instrument for routine clinical use.

Activities of Daily Living↗

PubMed2005

Targeting acetylcholinesterase and butyrylcholinesterase in dementia.

The cholinesterase inhibitors (ChE-Is) attenuate the cholinergic deficit underlying the cognitive and neuropsychiatric dysfunctions in patients with AD. Inhibition of brain acetylcholinesterase (AChE) has been the major therapeutic target of ChE-I treatment strategies for Alzheimer's disease (AD). AChE-positive neurons project diffusely to the cortex, modulating cortical processing and responses to new and relevant stimuli. Butyrylcholinesterase (BuChE)-positive neurons project specifically to the frontal cortex, and may have roles in attention, executive function, emotional memory and behaviour. Furthermore, BuChE activity progressively increases as the severity of dementia advances, while AChE activity declines. Therefore, inhibition of BuChE may provide additional benefits. The two cholinesterase (ChE) enzymes that metabolize acetylcholine (ACh) differ significantly in substrate specificity, enzyme kinetics, expression and activity in different brain regions, and complexity of gene regulation. In addition, recent evidence suggests that AChE and BuChE may have roles beyond 'classical' co-regulatory esterase functions in terminating ACh-mediated neurotransmission. 'Non-classical' roles in modulating the activity of other proteins, regional cerebral blood flow, tau phosphorylation, and the amyloid cascade may affect rates of AD progression. If these additional mechanisms are demonstrated to underlie clinically meaningful effects, modification of the over-simplistic cholinergic hypothesis in AD that is limited to symptomatic treatment, ignoring the potential of cholinergic therapies to modify the disease process, may be appropriate. The specificity of ChE inhibitory activity, up-regulation of AChE activity and changes in the composition of AChE molecular forms over time, selectivity for AD-relevant ChE molecular forms, brain vs. peripheral selectivity, and pharmacokinetic profile may be important determinants of the acute and long-term efficacy, safety and tolerability profiles of the different ChE-Is. This review focuses on new evidence for the roles of BuChE and AChE in symptom generation and rate of underlying disease progression in dementia, and argues that it may be appropriate to re-evaluate the place of ChE-Is in the treatment of dementia.

Acetylcholinesterase↗

PubMed2005

A phase 1 clinical trial of nerve growth factor gene therapy for Alzheimer disease.

Cholinergic neuron loss is a cardinal feature of Alzheimer disease. Nerve growth factor (NGF) stimulates cholinergic function, improves memory and prevents cholinergic degeneration in animal models of injury, amyloid overexpression and aging. We performed a phase 1 trial of ex vivo NGF gene delivery in eight individuals with mild Alzheimer disease, implanting autologous fibroblasts genetically modified to express human NGF into the forebrain. After mean follow-up of 22 months in six subjects, no long-term adverse effects of NGF occurred. Evaluation of the Mini-Mental Status Examination and Alzheimer Disease Assessment Scale-Cognitive subcomponent suggested improvement in the rate of cognitive decline. Serial PET scans showed significant (P < 0.05) increases in cortical 18-fluorodeoxyglucose after treatment. Brain autopsy from one subject suggested robust growth responses to NGF. Additional clinical trials of NGF for Alzheimer disease are warranted.

Aged↗

PubMed2005

Ziprasidone in acute bipolar mania: a 21-day randomized, double-blind, placebo-controlled replication trial.

BACKGROUND: In an earlier 21-day, placebo-controlled trial, ziprasidone was efficacious in improving symptoms of mania and was well tolerated. To confirm these results, a similarly designed 21-day trial was conducted. METHODS: Inpatients with bipolar I disorder, manic or mixed, were randomized to ziprasidone (40 to 80 mg BID) or placebo. Efficacy rating scales were derived from the Schedule for Affective Disorders and Schizophrenia-Change Bipolar Scale (SADS-CB). SADS-CB-derived Mania Rating Scale (MRS) total score was the primary efficacy parameter. Secondary SADS-CB-derived efficacy parameters included Manic Syndrome and Behavior and Ideation Subscales, Hamilton Depression Rating Scale (HAM-D), and the Montgomery Asberg Depression Rating Scale (MADRS). The Clinical Global Impression-Severity Scale (CGI-S), the Global Assessment of Functioning (GAF), and the Positive and Negative Syndrome Scale (PANSS) were also assessed. RESULTS: Sixty-five placebo and 137 ziprasidone patients were evaluable for efficacy. Baseline-to-endpoint mean changes in MRS scores were -11.1 for ziprasidone and -5.6 for placebo (all patients, last observation carried forward [LOCF]; P < 0.01). Ziprasidone produced significantly greater improvements in Manic Syndrome (P < or = 0.01) and Behavior and Ideation Subscales (P < or = 0.001), CGI-S score, (P < or = 0.001), PANSS Total (P < or = 0.01) and Positive Subscale (P < or = 0.001) scores, and GAF (P < or = 0.001). With ziprasidone, significant improvements were observed from Day 2 onward for MRS and CGI-S at all time points except Day 4 for MRS. Treatment-related discontinuations due to adverse events were 5.8% for ziprasidone and 1.5% for placebo (P = 0.20). CONCLUSIONS: Ziprasidone was well tolerated, rapidly efficacious, and superior to placebo in improving symptoms and global illness severity in these inpatients with acute bipolar mania, both manic and mixed episodes.

Acute Disease↗

PubMed2005

Synthesis and evaluation of nicotine alpha4beta2 receptor radioligand, 5-(3'-18F-fluoropropyl)-3-(2-(S)-pyrrolidinylmethoxy)pyridine, in rodents and PET in nonhuman primate.

UNLABELLED: Nicotine alpha(4)beta(2) receptor subtypes are implicated in the study of Alzheimer's disease, schizophrenia, substance abuse, lung cancer, and other disorders. We report the development and evaluation of a putative antagonist, 5-(3'-fluoropropyl)-3-(2-(S)-pyrrolidinylmethoxy)pyridine (nifrolidine) as a PET agent for nicotine alpha(4)beta(2) receptors. METHODS: In vitro binding affinity of nifrolidine was measured in rat brain slices labeled with (125)I-iodoepibatidine or (125)I-bungaratoxin. Selectivity of binding was measured in the presence of cytisine. (18)F radiolabeling was performed by reacting the tosylate precursor with (18)F-fluoride followed by deprotection. In vitro autoradiographic studies in rat brain slices with 5-(3'-(18)F-fluoropropyl)-3-(2-(S)-pyrrolidinylmethoxy)pyridine ((18)F-nifrolidine) were read on a phosphor imager. Rats were injected with (18)F-nifrolidine (3.7 MBq each), and brain regions were counted at various times (2-120 min). Blocking studies were performed by subcutaneous injection of nicotine (10 mg/kg). A PET study of (18)F-nifrolidine (approximately 148 MBq) was performed on an anesthetized rhesus monkey using a high-resolution scanner. RESULTS: In vitro binding affinity of nifrolidine exhibited an inhibition constant of 2.89 nmol/L for the alpha(4)beta(2) sites. Radiosynthesis and high-performance liquid chromatography purifications yielded the product in approximately 20%-40% decay-corrected radiochemical yield to provide (18)F-nifrolidine specific activities of approximately 111-185 GBq/mumol. In vitro autoradiography in rat brain slices revealed selective binding of (18)F-nifrolidine to the anteroventral thalamic nucleus, ventral posteriomedial thalamus, dorsolateral geniculate, and, to a lesser extent, cortex and striata, which are known to contain alpha(4)beta(2) sites. This specific binding was completely abolished by 300 mumol/L nicotine. Ex vivo rat brain distribution studies indicated selective binding in the thalamus with a maximal thalamus-to-cerebellum ratio of approximately 3. The PET study revealed selective maximal uptake (0.01% injected dose/mL) in regions of the thalamus (anteroventral and anteromedial thalamus, ventrolateral thalamus) and extrathalamic regions such as cingulate gyrus, lateral geniculate, temporal cortex, and frontal cortex. CONCLUSION: Binding of (18)F-nifrolidine to alpha(4)beta(2) receptor-rich regions in rats and monkeys indicates promise as a PET agent. Additionally, the thalamus-to-cerebellum ratio approached a plateau of 1.7 in 120 min, indicating relatively faster kinetics compared with previously reported imaging agents.

Animals↗