1
|
Gil-Rivas A, de Pascual-Teresa B, Ortín I, Ramos A. New Advances in the Exploration of Esterases with PET and Fluorescent Probes. Molecules 2023; 28:6265. [PMID: 37687094 PMCID: PMC10488407 DOI: 10.3390/molecules28176265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/11/2023] [Accepted: 08/14/2023] [Indexed: 09/10/2023] Open
Abstract
Esterases are hydrolases that catalyze the hydrolysis of esters into the corresponding acids and alcohols. The development of fluorescent probes for detecting esterases is of great importance due to their wide spectrum of biological and industrial applications. These probes can provide a rapid and sensitive method for detecting the presence and activity of esterases in various samples, including biological fluids, food products, and environmental samples. Fluorescent probes can also be used for monitoring the effects of drugs and environmental toxins on esterase activity, as well as to study the functions and mechanisms of these enzymes in several biological systems. Additionally, fluorescent probes can be designed to selectively target specific types of esterases, such as those found in pathogenic bacteria or cancer cells. In this review, we summarize the recent fluorescent probes described for the visualization of cell viability and some applications for in vivo imaging. On the other hand, positron emission tomography (PET) is a nuclear-based molecular imaging modality of great value for studying the activity of enzymes in vivo. We provide some examples of PET probes for imaging acetylcholinesterases and butyrylcholinesterases in the brain, which are valuable tools for diagnosing dementia and monitoring the effects of anticholinergic drugs on the central nervous system.
Collapse
Affiliation(s)
- Alba Gil-Rivas
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
| | - Beatriz de Pascual-Teresa
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
| | - Irene Ortín
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
| | - Ana Ramos
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
| |
Collapse
|
2
|
Abstract
This article presents an overview of imaging agents for PET that have been applied for research and diagnostic purposes in patients affected by dementia. Classified by the target which the agents visualize, seven groups of tracers can be distinguished, namely radiopharmaceuticals for: (1) Misfolded proteins (ß-amyloid, tau, α-synuclein), (2) Neuroinflammation (overexpression of translocator protein), (3) Elements of the cholinergic system, (4) Elements of monoamine neurotransmitter systems, (5) Synaptic density, (6) Cerebral energy metabolism (glucose transport/ hexokinase), and (7) Various other proteins. This last category contains proteins involved in mechanisms underlying neuroinflammation or cognitive impairment, which may also be potential therapeutic targets. Many receptors belong to this category: AMPA, cannabinoid, colony stimulating factor 1, metabotropic glutamate receptor 1 and 5 (mGluR1, mGluR5), opioid (kappa, mu), purinergic (P2X7, P2Y12), sigma-1, sigma-2, receptor for advanced glycation endproducts, and triggering receptor expressed on myeloid cells-1, besides several enzymes: cyclooxygenase-1 and 2 (COX-1, COX-2), phosphodiesterase-5 and 10 (PDE5, PDE10), and tropomyosin receptor kinase. Significant advances in neuroimaging have been made in the last 15 years. The use of 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) for quantification of regional cerebral glucose metabolism is well-established. Three tracers for ß-amyloid plaques have been approved by the Food and Drug Administration and European Medicines Agency. Several tracers for tau neurofibrillary tangles are already applied in clinical research. Since many novel agents are in the preclinical or experimental stage of development, further advances in nuclear medicine imaging can be expected in the near future. PET studies with established tracers and tracers for novel targets may result in early diagnosis and better classification of neurodegenerative disorders and in accurate monitoring of therapy trials which involve these targets. PET data have prognostic value and may be used to assess the response of the human brain to interventions, or to select the appropriate treatment strategy for an individual patient.
Collapse
Affiliation(s)
- Aren van Waarde
- University of Groningen, University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Groningen, the Netherlands.
| | - Sofia Marcolini
- University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, the Netherlands
| | - Peter Paul de Deyn
- University of Groningen, University Medical Center Groningen, Department of Neurology, Groningen, the Netherlands; University of Antwerp, Born-Bunge Institute, Neurochemistry and Behavior, Campus Drie Eiken, Wilrijk, Belgium
| | - Rudi A J O Dierckx
- University of Groningen, University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Groningen, the Netherlands; Ghent University, Ghent, Belgium
| |
Collapse
|
3
|
Gnesin S, Müller J, Burger IA, Meisel A, Siano M, Früh M, Choschzick M, Müller C, Schibli R, Ametamey SM, Kaufmann PA, Treyer V, Prior JO, Schaefer N. Radiation dosimetry of 18F-AzaFol: A first in-human use of a folate receptor PET tracer. EJNMMI Res 2020; 10:32. [PMID: 32270313 PMCID: PMC7142191 DOI: 10.1186/s13550-020-00624-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 03/27/2020] [Indexed: 12/21/2022] Open
Abstract
Background The folate receptor alpha (FRα) is an interesting target for imaging and therapy of different cancers. We present the first in-human radiation dosimetry and radiation safety results acquired within a prospective, multicentric trial (NCT03242993) evaluating the 18F-AzaFol (3′-aza-2′-[18F]fluorofolic acid) as the first clinically assessed PET tracer targeting the FRα. Material and methods Six eligible patients presented a histologically confirmed adenocarcinoma of the lung with measurable lesions (≥ 10 mm according to RECIST 1.1). TOF-PET images were acquired at 3, 11, 18, 30, 40, 50, and 60 min after the intravenous injection of 327 MBq (range 299–399 MBq) of 18F-AzaFol to establish dosimetry. Organ absorbed doses (AD), tumor AD, and patient effective doses (E) were assessed using the OLINDA/EXM v.2.0 software and compared with pre-clinical results. Results No serious related adverse events were observed. The highest AD were in the liver, the kidneys, the urinary bladder, and the spleen (51.9, 45.8, 39.1, and 35.4 μGy/MBq, respectively). Estimated patient and gender-averaged E were 18.0 ± 2.6 and 19.7 ± 1.4 μSv/MBq, respectively. E in-human exceeded the value of 14.0 μSv/MBq extrapolated from pre-clinical data. Average tumor AD was 34.8 μGy/MBq (range 13.6–60.5 μGy/MBq). Conclusions 18F-Azafol is a PET agent with favorable dosimetric properties and a reasonable radiation dose burden for patients which merits further evaluation to assess its performance. Trial registration ClinicalTrial.gov, NCT03242993, posted on August 8, 2017
Collapse
Affiliation(s)
- Silvano Gnesin
- Institute of Radiation Physics, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Joachim Müller
- Department of Radiology and Nuclear Medicine, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
| | - Irene A Burger
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland.,Department of Nuclear Medicine, Kantonsspital Baden, Baden, Switzerland
| | - Alexander Meisel
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland.,Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.,Department of Internal Medicine-Hematology & Oncology, Stadtspital Waid, Zurich, Switzerland
| | - Marco Siano
- Department of Oncology and Hematology, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
| | - Martin Früh
- Department of Oncology and Hematology, Cantonal Hospital St. Gallen, St. Gallen, Switzerland.,University of Bern, Bern, Switzerland
| | - Matthias Choschzick
- Institute for Pathology and Molecular Pathology, University Hospital of Zurich, Zurich, Switzerland
| | - Cristina Müller
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.,Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, Villigen-PSI, Villigen, Switzerland
| | - Roger Schibli
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.,Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, Villigen-PSI, Villigen, Switzerland
| | - Simon M Ametamey
- Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | - Philipp A Kaufmann
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland
| | - Valerie Treyer
- Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland
| | - John O Prior
- Department of Nuclear Medicine and Molecular Imaging, Lausanne University Hospital and University of Lausanne, Rue du Bugnon 46, CH-1011, Lausanne, Switzerland.
| | - Niklaus Schaefer
- Department of Nuclear Medicine and Molecular Imaging, Lausanne University Hospital and University of Lausanne, Rue du Bugnon 46, CH-1011, Lausanne, Switzerland
| |
Collapse
|
4
|
Bruno JL, Hosseini SH, Lightbody AA, Manchanda MK, Reiss AL. Brain circuitry, behavior, and cognition: A randomized placebo-controlled trial of donepezil in fragile X syndrome. J Psychopharmacol 2019; 33:975-985. [PMID: 31264943 PMCID: PMC6894490 DOI: 10.1177/0269881119858304] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND Fragile X syndrome, the most common inherited cause for intellectual disability, is associated with alterations in cholinergic among other neurotransmitter systems. This study investigated the effects of donepezil hydrochloride, a cholinesterase inhibitor that has potential to correct aberrant cholinergic signaling. METHOD Forty-two individuals with fragile X syndrome (mean age=19.61 years) were randomized to receive 2.5-10.0 mg of donepezil (n=20, seven females) or placebo (n=22, eight females) per day. One individual in the active group withdrew at week 7. Outcomes included the contingency naming test, the aberrant behavior checklist, and behavior and brain activation patterns during a functional magnetic resonance imaging gaze discrimination task. RESULTS There were no significant differences between active and placebo groups on cognitive (contingency naming task) or behavioral (total score or subscales of the aberrant behavior checklist) outcomes. At baseline, the active and placebo groups did not differ in functional magnetic resonance imaging activation patterns during the gaze task. After 12 weeks of treatment the active group displayed reduced activation in response to the averted vs direct gaze contrast, relative to the placebo group, in the left superior frontal gyrus. CONCLUSIONS Reduced functional brain activation for the active group may represent less arousal in response to direct eye gaze, relative to the placebo group. Change in functional magnetic resonance imaging activation patterns may serve as a more sensitive metric and predictor of response to treatment when compared to cognitive and behavioral assessments. Our results suggest that donepezil may have an impact on brain functioning, but longer term follow-up and concomitant behavioral intervention may be required to demonstrate improvement in cognition and behavior.
Collapse
Affiliation(s)
- Jennifer L. Bruno
- Center for Interdisciplinary Brain Sciences Research, Stanford University.,To whom correspondence should be addressed: 401 Quarry Road, Palo Alto, CA 94304, Phone: 818-415-9119, Fax: (650) 724-4761,
| | - S.M. Hadi Hosseini
- Center for Interdisciplinary Brain Sciences Research, Stanford University
| | - Amy A. Lightbody
- Center for Interdisciplinary Brain Sciences Research, Stanford University
| | - Mai K. Manchanda
- Center for Interdisciplinary Brain Sciences Research, Stanford University
| | - Allan L. Reiss
- Center for Interdisciplinary Brain Sciences Research, Stanford University.,Department of Radiology, Stanford University.,Department of Pediatrics, Stanford University
| |
Collapse
|
5
|
Neumann KD, Thompson CM, Blecha JE, Gerdes JM, VanBrocklin HF. An improved radiosynthesis of O-(2-[ 18 F]fluoroethyl)-O-(p-nitrophenyl)methylphosphonate: A first-in-class cholinesterase PET tracer. J Labelled Comp Radiopharm 2017; 60:337-342. [PMID: 28406525 DOI: 10.1002/jlcr.3511] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 03/31/2017] [Accepted: 04/05/2017] [Indexed: 11/06/2022]
Abstract
O-(2-Fluoroethyl)-O-(p-nitrophenyl) methylphosphonate 1 is an organophosphate cholinesterase inhibitor that creates a phosphonyl-serine covalent adduct at the enzyme active site blocking cholinesterase activity in vivo. The corresponding radiolabeled O-(2-[18 F]fluoroethyl)-O-(p-nitrophenyl) methylphosphonate, [18 F]1, has been previously prepared and found to be an excellent positron emission tomography imaging tracer for assessment of cholinesterases in live brain, peripheral tissues, and blood. However, the previously reported [18 F]1 tracer synthesis was slow even with microwave acceleration, required high-performance liquid chromatography separation of the tracer from impurities, and gave less optimal radiochemical yields. In this paper, we report a new synthetic approach to circumvent these shortcomings that is reliant on the facile reactivity of bis-(O,O-p-nitrophenyl) methylphosphonate, 2, with 2-fluoroethanol in the presence of DBU. The cold synthesis was successfully translated to provide a more robust radiosynthesis. Using this new strategy, the desired tracer, [18 F]1, was obtained in a non-decay-corrected radiochemical yield of 8 ± 2% (n = 7) in >99% radiochemical and >95% chemical purity with a specific activity of 3174 ± 345 Ci/mmol (EOS). This new facile radiosynthesis routinely affords highly pure quantities of [18 F]1, which will further enable tracer development of OP cholinesterase inhibitors and their evaluation in vivo.
Collapse
Affiliation(s)
- Kiel D Neumann
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Charles M Thompson
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, MT, USA
| | - Joseph E Blecha
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - John M Gerdes
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, MT, USA
| | - Henry F VanBrocklin
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| |
Collapse
|
6
|
PET Radioligands for Imaging of Tau Pathology: Current Status. Nucl Med Mol Imaging 2015; 49:251-7. [PMID: 26550043 DOI: 10.1007/s13139-015-0374-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 09/08/2015] [Accepted: 09/14/2015] [Indexed: 12/13/2022] Open
Abstract
The incidence of Alzheimer's disease (AD), a progressive neurodegenerative disorder, continues to soar with the rapid growth of the elderly population, thus creating an enormous social and economic burden. Although disease-modifying drugs to treat AD are not yet available, several candidate drugs are in clinical trials. Most of these drugs are expected to be effective at the early stages of the disease, and therefore the early and accurate diagnosis of AD will be a critical factor in efforts to improve the prognosis of patients with AD. This review focuses on lead radioligands developed to date and their preclinical data in order to facilitate the development of tau-specific positron emission tomography radioligands that are of great interest to the scientific community.
Collapse
|
7
|
Redolfi A, Bosco P, Manset D, Frisoni GB. Brain investigation and brain conceptualization. FUNCTIONAL NEUROLOGY 2014; 28:175-90. [PMID: 24139654 DOI: 10.11138/fneur/2013.28.3.175] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The brain of a patient with Alzheimer's disease (AD) undergoes changes starting many years before the development of the first clinical symptoms. The recent availability of large prospective datasets makes it possible to create sophisticated brain models of healthy subjects and patients with AD, showing pathophysiological changes occurring over time. However, these models are still inadequate; representations are mainly single-scale and they do not account for the complexity and interdependence of brain changes. Brain changes in AD patients occur at different levels and for different reasons: at the molecular level, changes are due to amyloid deposition; at cellular level, to loss of neuron synapses, and at tissue level, to connectivity disruption. All cause extensive atrophy of the whole brain organ. Initiatives aiming to model the whole human brain have been launched in Europe and the US with the goal of reducing the burden of brain diseases. In this work, we describe a new approach to earlier diagnosis based on a multimodal and multiscale brain concept, built upon existing and well-characterized single modalities.
Collapse
|
8
|
Persson M, El Ali HH, Binderup T, Pfeifer A, Madsen J, Rasmussen P, Kjaer A. Dosimetry of 64Cu-DOTA-AE105, a PET tracer for uPAR imaging. Nucl Med Biol 2014; 41:290-5. [DOI: 10.1016/j.nucmedbio.2013.12.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 11/28/2013] [Accepted: 12/07/2013] [Indexed: 01/08/2023]
|
9
|
|
10
|
Relkin NR. Beyond symptomatic therapy: a re-examination of acetylcholinesterase inhibitors in Alzheimer’s disease. Expert Rev Neurother 2014; 7:735-48. [PMID: 17561789 DOI: 10.1586/14737175.7.6.735] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Acetylcholinesterase inhibitors (AChEIs) are generally regarded as palliative treatments for Alzheimer's disease that slow the progression of dementia symptoms without altering Alzheimer's disease's underlying pathogenic mechanisms. This concept is based on inference rather than evidence, and has limited the scope and persistence of AChEI use in clinical practice. Recent preclinical studies demonstrate that AChEIs exhibit a number of biological effects in addition to cholinesterase inhibition. A broader understanding of the possible mechanisms of action of AChEIs in Alzheimer's disease could result in more effective use and assist in the development of new and improved therapies. The available evidence brings into question the prevailing view that AChEIs are exclusively symptomatic treatments and supports the use of these agents persistently throughout the course of Alzheimer's disease.
Collapse
Affiliation(s)
- Norman R Relkin
- Joan and Sanford I. Weill Medical College of Cornell University, 428 East 72nd Street, Suite 500, NY 10017, USA.
| |
Collapse
|
11
|
Kikuchi T, Okamura T, Zhang MR, Irie T. PET probes for imaging brain acetylcholinesterase. J Labelled Comp Radiopharm 2013; 56:172-9. [DOI: 10.1002/jlcr.3002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Revised: 11/08/2012] [Accepted: 11/08/2012] [Indexed: 12/31/2022]
Affiliation(s)
- Tatsuya Kikuchi
- Probe Research Team, Molecular Probe Program, Molecular Imaging Center; National Institute of Radiological Sciences; Chiba; 263-8555; Japan
| | - Toshimitsu Okamura
- Probe Research Team, Molecular Probe Program, Molecular Imaging Center; National Institute of Radiological Sciences; Chiba; 263-8555; Japan
| | - Ming-Rong Zhang
- Probe Research Team, Molecular Probe Program, Molecular Imaging Center; National Institute of Radiological Sciences; Chiba; 263-8555; Japan
| | - Toshiaki Irie
- Probe Research Team, Molecular Probe Program, Molecular Imaging Center; National Institute of Radiological Sciences; Chiba; 263-8555; Japan
| |
Collapse
|
12
|
Sakata M, Oda K, Toyohara J, Ishii K, Nariai T, Ishiwata K. Direct comparison of radiation dosimetry of six PET tracers using human whole-body imaging and murine biodistribution studies. Ann Nucl Med 2013; 27:285-96. [DOI: 10.1007/s12149-013-0685-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 01/06/2013] [Indexed: 11/30/2022]
|
13
|
van der Aart J, Hallett WA, Rabiner EA, Passchier J, Comley RA. Radiation dose estimates for carbon-11-labelled PET tracers. Nucl Med Biol 2012; 39:305-14. [DOI: 10.1016/j.nucmedbio.2011.08.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 07/12/2011] [Accepted: 08/03/2011] [Indexed: 12/01/2022]
|
14
|
Binding of 2-[18F]fluoro-CP-118,954 to mouse acetylcholinesterase: microPET and ex vivo Cerenkov luminescence imaging studies. Nucl Med Biol 2011; 38:541-7. [DOI: 10.1016/j.nucmedbio.2010.11.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 11/13/2010] [Accepted: 11/28/2010] [Indexed: 11/17/2022]
|
15
|
Chung KA, Lobb BM, Nutt JG, Horak FB. Effects of a central cholinesterase inhibitor on reducing falls in Parkinson disease. Neurology 2010; 75:1263-9. [PMID: 20810998 DOI: 10.1212/wnl.0b013e3181f6128c] [Citation(s) in RCA: 174] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To investigate if a central cholinesterase inhibitor will reduce falling frequency in subjects with Parkinson disease (PD) with advanced postural instability. BACKGROUND Falling due to postural instability is a significant problem in advancing PD, and is minimally impacted by dopaminergic therapy. Anticholinergic medications increase falling in the elderly. Further, CNS cholinergic neuron loss occurs in PD. We hypothesized that acetylcholine augmentation may reduce frequent falling in subjects with PD. METHODS We enrolled 23 subjects with PD who reported falling or nearly falling more than 2 times per week. In a randomized, placebo-controlled, crossover design, subjects were given 6 weeks of donepezil or placebo with a 3-week washout between phases. The primary outcomes were daily falls and near falls reported on postcards. Secondary outcomes included scores on the Activities of Balance Confidence Scale, Berg Balance Scale, Clinical Global Impression of Change, Folstein Mini-Mental State Examination, and the motor section of the Unified Parkinson's Disease Rating Scale. RESULTS Fall frequency per day on placebo was 0.25 ± 0.08 (SEM) compared with 0.13 ± 0.03 on donepezil (p < 0.05). The frequency of near falls was not significantly different between phases. The secondary outcomes did not differ; however, there was a trend to improvement on the subject-completed Global Impression of Change scale. CONCLUSIONS Subjects with PD fell approximately half as often during the 6 weeks on donepezil than on placebo. Larger trials of cholinergic augmentation are warranted in subjects with PD with frequent falls. CLASSIFICATION OF EVIDENCE This study provides Class II evidence that donepezil (maximum 10 mg per day) significantly reduced the number of falls in patients with PD (0.13 falls/day, SEM = 0.03) than when taking placebo (0.25 falls/day, SEM = 0.08, p = 0.049).
Collapse
Affiliation(s)
- Kathryn A Chung
- Department of Neurology, Oregon Health & Science University, Portland, OR, USA.
| | | | | | | |
Collapse
|
16
|
Herholz K. Acetylcholine esterase activity in mild cognitive impairment and Alzheimer's disease. Eur J Nucl Med Mol Imaging 2008; 35 Suppl 1:S25-9. [PMID: 18196237 DOI: 10.1007/s00259-007-0699-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
PURPOSE Impairment of cholinergic neurotransmission is a well-established fact in Alzheimer's disease (AD), but there is controversy about its relevance at the early stages of the disease and in mild cognitive impairment (MCI). METHODS In vivo positron emission tomography imaging of cortical acetylcholine esterase (AChE) activity as a marker of cholinergic innervation that is expressed by cholinergic axons and cholinoceptive neurons has demonstrated a reduction of this enzyme activity in manifest AD. The technique is also useful to measure the inhibition of cerebral AChE induced by cholinesterase inhibitors for treatment of dementia symptoms. RESULTS A reduction of cortical AchE activity was found consistently in all studies of AD and in few cases of MCI who later concerted to AD. CONCLUSION The in vivo findings in MCI and very mild AD are still preliminary, and studies seem to suggest that cholinergic innervation and AChE as the main degrading enzyme are both reduced, which might result in partial compensation of their effect.
Collapse
Affiliation(s)
- Karl Herholz
- Wolfson Molecular Imaging Centre, Clinical Neuroscience, University of Manchester, 27 Palatine Road, Manchester, UK.
| |
Collapse
|
17
|
Okamura N, Funaki Y, Tashiro M, Kato M, Ishikawa Y, Maruyama M, Ishikawa H, Meguro K, Iwata R, Yanai K. In vivo visualization of donepezil binding in the brain of patients with Alzheimer's disease. Br J Clin Pharmacol 2007; 65:472-9. [PMID: 18070217 DOI: 10.1111/j.1365-2125.2007.03063.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT * Deficit in central cholinergic neurotransmission is a consistent change associated with Alzheimer's disease (AD). * Donepezil hydrochloride exhibits selective inhibition of acetylcholinesterase (AChE) and is widely used for the treatment of AD. * The biodistribution of donepezil in the brain after administration is not precisely understood in vivo. * There is no method to measure the amount of binding of orally administered donepezil to AChE. WHAT THIS STUDY ADDS * This study clearly visualizes the distribution of donepezil in human brain using [(11)C]-donepezil and positron emission tomography. * This study demonstrates prominent reduction of the donepezil binding site in the AD brain. * This study provides methodology to measure the AChE binding occupancy of orally administered donepezil and provides a new surrogate marker for evaluation and prediction of response to donepezil treatment. AIMS The aims of this study were to visualize in vivo binding of donepezil to acetylcholinesterase (AChE) in the brain and to establish a method for measuring the amount of binding of orally administered donepezil. METHODS [5-(11)C-methoxy]-donepezil ([(11)C]-donepezil) was radiolabelled as a positron emission tomography (PET) tracer. The biodistribution of [(11)C]-donepezil was measured by PET in 10 AD patients and six elderly normal subjects. Two AD patients underwent additional PET measurements after oral administration of donepezil for 6 months. RESULTS [(11)C]-donepezil-PET images demonstrated high densities of tracer distribution in AChE-rich brain regions such as the striatum, thalamus, and cerebellum. Compared with elderly normal subjects, patients with mild AD exhibited about 18-20% reduction of donepezil binding in the neocortex and hippocampus, while patients with moderate AD exhibited about 24-30% reduction of donepezil binding throughout the brain. Orally administered donepezil (5 mg day(-1)) induced 61.6-63.3% reduction of donepezil binding in AD brains. The distribution volume of [(11)C]-donepezil in the hippocampus was significantly correlated with MMSE scores in AD patients. CONCLUSIONS [(11)C]-donepezil-PET enables quantitative measurement of donepezil binding in the brain. AD patients exhibited reduction of donepezil binding in the brain, even in the early stage of disease. Longitudinal evaluation by this technique enables determination of AChE binding occupancy of orally administered donepezil.
Collapse
Affiliation(s)
- Nobuyuki Okamura
- Department of Pharmacology, Tohoku University Graduate School of Medicine, Sendai, Japan.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Herholz K, Weisenbach S, Kalbe E. Deficits of the cholinergic system in early AD. Neuropsychologia 2007; 46:1642-7. [PMID: 18201734 DOI: 10.1016/j.neuropsychologia.2007.11.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Revised: 11/07/2007] [Accepted: 11/28/2007] [Indexed: 10/22/2022]
Abstract
Impairment of cholinergic neurotransmission is a well-established fact in Alzheimer's disease (AD) but there is controversy about its relevance at the early stages of the disease. In the recent years new techniques for in vivo imaging of key components of the cholinergic system in humans have developed. They are beginning to be applied to the very early stages of AD. Preliminary results suggest that there is early impairment of presynaptic receptors and acetylcholine esterase, the main degrading enzyme for acetylcholine, in cerebral cortex. The relation of these findings to neuronal function and post-mortem findings is being discussed.
Collapse
|
19
|
Lee I, Choe YS, Ryu EK, Choi BW, Choi JY, Choi Y, Lee KH, Kim BT. Synthesis and evaluation of radioiodine-labelled CP-118,954 for the in-vivo imaging of acetylcholinesterase. Nucl Med Commun 2007; 28:561-6. [PMID: 17538398 DOI: 10.1097/mnm.0b013e328194f1f7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES Alzheimer's disease (AD) is characterized by reduced acetylcholinesterase (AChE) activity in the post-mortem tissues of AD patients. Therefore, AChE has been an attractive target for the diagnosis of AD. In the present study, 5,7-dihydro-3-[2-(1-(phenylmethyl)-4-piperidinyl)ethyl]-6H-pyrrolo[3,2-f]-1,2-benzisoxazol-6-one (CP-118,954), a potent AChE inhibitor, was labelled with radioiodine and evaluated as an AChE imaging agent for SPECT. METHODS Radioiodine-labelled CP-118,954 was prepared from CP-144,885 and [(125)I]iodobenzyl bromide, and anti-AChE activities of iodine-substituted CP-118,954 were measured. Metabolism studies were carried out in samples of blood and whole brain of mice injected with 2-[(123)I]iodo-CP-118,954 ((123)I-1). Tissue distribution studies were also performed in mice injected with I-1, and samples of blood, thyroid, stomach, and brain tissue (cerebellum, striatum and cortex) were removed, weighed and counted. RESULTS Of the ligands, 2-iodo-CP-118,954 exhibited higher binding affinity for AChE (IC50=24 nM) than the other positional isomers. 2-[(125)I]Iodo-CP-118,954 was found to have a lipophilicity (log P=2.1) favouring brain permeability and metabolic stability in mouse brain, but a marginal target (striatum) to non-target (cerebellum) uptake ratio (1.1) in mouse brain. CONCLUSION This result demonstrates that 2-[(125)I]iodo-CP-118,954 may be unsuitable for AChE imaging. These findings suggest that radioligands suitable for AChE imaging should have not only a specific structure but also a sub-nanomolar to low nanomolar IC50.
Collapse
Affiliation(s)
- Iljung Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul 135-710, Korea
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Abstract
Donepezil hydrochloride is the most widely prescribed drug for Alzheimer's disease (AD). The main mechanism of action through which it influences cognition and function is presumed to be the inhibition of acetylcholinesterase enzyme in the brain; however, donepezil may also impact the pathophysiology of AD at several other points. Officially approved for mild-to-moderate and severe AD, donepezil has also been shown to be effective in early-stage AD, vascular dementia, Parkinson's disease dementia/Lewy body disease and cognitive symptoms associated with multiple sclerosis. In addition, one study suggested that donepezil may delay the onset of AD in subjects with mild cognitive impairment, a prodrome to AD. The pharmacokinetics, pharmacodynamics, safety/tolerability profile and drug interaction properties of donepezil make it an easy and safe agent to use. However, in general, the efficacy of donepezil is limited, and ongoing studies are investigating other agents that may ultimately overtake its present position as the mainstay of anti-AD therapy.
Collapse
Affiliation(s)
- Ben Seltzer
- V.A. Boston Healthcare System, Department of Neurology, Harvard Medical School, Geriatric Research Center, Boston, MA 02130, USA.
| |
Collapse
|
21
|
Lee SY, Choe YS, Ryu EK, Iimura Y, Choi Y, Lee KH, Kim BT. Is subnanomolar binding affinity required for the in vivo imaging of acetylcholinesterase? Studies on 18F-labeled G379. Nucl Med Biol 2006; 33:91-4. [PMID: 16459263 DOI: 10.1016/j.nucmedbio.2005.10.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 09/27/2005] [Accepted: 10/03/2005] [Indexed: 11/26/2022]
Abstract
Acetylcholinesterase (AChE) is an important cholinergic marker of Alzheimer's disease (AD) and shows reduced activity in postmortem AD brain tissues. 1-(4-Fluorobenzyl)-4-[(5,6-dimethoxy-1-oxoindan-2-fluoro-2-yl)methyl]piperidine (G379, ), an AChE inhibitor with a subnanomolar IC(50) (0.56 nM), was prepared as a (18)F-labeled radioligand ([(18)F]) and evaluated in mice. Metabolism studies of [(18)F] showed no metabolites in the mouse brain. Tissue distribution studies demonstrated its uniform regional distribution in the mouse brain, suggesting that this radioligand is not suitable for the in vivo imaging of AChE. This result along with reports on radiolabeled N-benzylpiperidine lactam benzisoxazole (IC(50) < 1 nM) and other radiolabeled benzylpiperidine derivatives (IC(50) > 1 nM) suggested that a subnanomolar IC(50) may not be the only important factor in determining the suitability of a radioligand for in vivo studies of AChE.
Collapse
Affiliation(s)
- Sang-Yoon Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | | | | | | | | | | | | |
Collapse
|
22
|
Abstract
Donepezil is a selective acetylcholinesterase inhibitor that is widely prescribed for Alzheimer's disease (AD). It has been shown to be of benefit in mild, moderate and severe stages of AD, vascular dementia and dementia associated with Parkinson's disease. Donepezil is absorbed slowly, but completely, from the gut, reaching peak plasma levels in 3-4 h and, with daily dosing, steady-state concentration in 15-21 days. Within a relatively narrow range, there is a linear relationship between dose and pharmacodynamic effects, measured as red blood cell acetylcholinesterase inhibition and clinical efficacy. Donepezil is principally excreted unchanged in the urine, but there is also hepatic metabolism; some of its metabolites may be active. Despite being 96% bound to plasma proteins, it has few interactions with other drugs, and the 5-mg dose can be given safely to patients with mild-to-moderate hepatic and renal -disease. Side effects, which are mainly a consequence of its cholinomimetic mechanism of action, are usually mild and transient. Although donepezil was originally developed to inhibit the breakdown of the neurotransmitter acetylcholine as symptomatic therapy for AD, recent studies raise the possibility of other effects this drug has on the pathogenesis of AD.
Collapse
Affiliation(s)
- Ben Seltzer
- Tulane University School of Medicine, Department of Psychiatry and Neurology, 1430 Tulane Avenue (HC82), New Orleans, Louisiana 70112, USA.
| |
Collapse
|
23
|
Abstract
Donepezil is an acetylcholinesterase inhibitor used to treat Alzheimer's disease. It has been shown to be effective in the treatment of cognitive symptoms, functional impairment and behavioral problems at mild, moderate and severe stages of the disease. Donepezil treatment results in modest short-term (6- to 9-month) improvement in some measures and attenuates the downward course of the disease for 1–3 years. Donepezil reaches peak plasma levels 3–4 h after ingestion and, with daily dosing, steady-state concentration in 14–21 days. The elimination half-life is approximately 70 h, and it is principally excreted unchanged in the urine. There is a linear relationship between plasma level and both red blood cell acetylcholinesterase inhibition and certain cognitive outcome measures. Donepezil is generally safe and well tolerated and, because of its dosing schedule, convenient to prescribe. Ongoing studies are examining the use of donepezil in combination with other drugs for Alzheimer's disease and for other conditions involving cognitive dysfunction.
Collapse
Affiliation(s)
- Ben Seltzer
- Tulane University School of Medicine, Department of Psychiatry and Neurology, 1430 Tulane Avenue (HC82), New Orleans, LA 70112, USA
| |
Collapse
|
24
|
Bohnen NI, Kaufer DI, Hendrickson R, Ivanco LS, Lopresti BJ, Koeppe RA, Meltzer CC, Constantine G, Davis JG, Mathis CA, Dekosky ST, Moore RY. Degree of inhibition of cortical acetylcholinesterase activity and cognitive effects by donepezil treatment in Alzheimer's disease. J Neurol Neurosurg Psychiatry 2005; 76:315-9. [PMID: 15716518 PMCID: PMC1739536 DOI: 10.1136/jnnp.2004.038729] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVES To determine in vivo cortical acetylcholinesterase (AChE) activity and cognitive effects in subjects with mild Alzheimer's disease (AD, n = 14) prior to and after 12 weeks of donepezil therapy. METHODS Cognitive and N-[(11)C]methyl-piperidin-4-yl propionate ([(11)C]PMP) AChE positron emission tomography (PET) assessments before and after donepezil therapy. RESULTS Analysis of the PET data revealed mean (temporal, parietal, and frontal) cortical donepezil induced AChE inhibition of 19.1% (SD 9.4%) (t = -7.9; p<0.0001). Enzyme inhibition was most robust in the anterior cingulate cortex (24.2% (6.9%), t = -14.1; p<0.0001). Donepezil induced cortical inhibition of AChE activity correlated with changes in the Stroop Color Word interference scores (R(2) = 0.59, p<0.01), but not with primary memory test scores. Analysis of the Stroop test data indicated that subjects with AChE inhibition greater than the median value (>22.2%) had improved scores on the Stroop Color Word Test compared with subjects with less inhibition who had stable to worsening scores (t = -2.7; p<0.05). CONCLUSIONS Donepezil induced inhibition of cortical AChE enzyme activity is modest in patients with mild AD. The degree of cortical enzyme inhibition correlates with changes in executive and attentional functions.
Collapse
Affiliation(s)
- N I Bohnen
- University of Pittsburgh, Liliane S Kaufmann Building, Suite 811, 3471 Fifth Avenue, Pittsburgh, PA 15213, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Ryu EK, Choe YS, Park EY, Paik JY, Kim YR, Lee KH, Choi Y, Kim SE, Kim BT. Synthesis and evaluation of 2-[18F]fluoro-CP-118,954 for the in vivo mapping of acetylcholinesterase. Nucl Med Biol 2005; 32:185-91. [PMID: 15721764 DOI: 10.1016/j.nucmedbio.2004.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2004] [Revised: 09/13/2004] [Accepted: 09/17/2004] [Indexed: 10/25/2022]
Abstract
5,7-Dihydro-3-[2-[1-(2-fluorobenzyl)-4-piperidinyl]ethyl]-6H-pyrrolo[3,2,f]-1,2-benzisoxazol-6-one (2-flouro-CP-118,954; 1), a potent acetylcholinesterase (AChE) inhibitor, was prepared as a radioligand by reductive alkylation of CP-144,885 the debenzylated form of CP 118,954, with 2-[18F]fluorobenzaldehyde. The decay-corrected radiochemical yield was 25-30% and the effective specific activity was 41-53 GBq/micromol. Tissue distribution studies of 2-[18F]fluoro-CP-118,954 ([18F]1) in mice showed that the regional brain distribution correlated well with the known density of AChE in the mouse brain. A high level of uptake in the striatum was also shown at all time points in the olfactory tubercle, which is known to have dopaminergic neurons. Blocking studies showed that radioligand uptake in all brain regions was not altered by either the dopamine receptor antagonists or the sigma receptor agonist. On the other hand, radioligand uptake in both the striatum and the olfactory tubercle was significantly blocked (80%) by ligand 1. The low level of bone uptake over time suggested that [18F]1 underwent little in vivo metabolic defluorination. The lack of metabolite formation in the mouse brain indicated that the regional distribution was attributed to [18F]1. These results demonstrated that [18F]1 binds specifically and selectively to AChE in mice and appears to be a suitable radioligand for the in vivo mapping of AChE.
Collapse
Affiliation(s)
- Eun Kyoung Ryu
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 135-710 Seoul, Republic of Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Scott Mason N, Mathis CA. Positron Emission Tomography Agents for Central Nervous System Drug Development Applications. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2005. [DOI: 10.1016/s0065-7743(05)40004-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
|
27
|
Lee SY, Choe YS, Kim YR, Paik JY, Choi BW, Kim SE, Lee KH, Choi Y, Kim BT. Synthesis and evaluation of 5,7-dihydro-3-[2-[1-(4-[18F]-fluorobenzyl)-4-piperidinyl]ethyl]-6H-pyrrolo[3,2-f]-1,2-benzisoxazol-6-one for in vivo mapping of acetylcholinesterase*. Nucl Med Commun 2004; 25:591-6. [PMID: 15167519 DOI: 10.1097/01.mnm.0000126629.09543.1d] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Acetylcholinesterase (AChE) is an important cholinergic marker for the diagnosis of Alzheimer's disease (AD). A recent study has demonstrated that C-labelled 5,7-dihydro-7-methyl-3-[2-[1-(phenylmethyl)-4-piperidinyl]ethyl]-6H-pyrrolo[3,2-f]-1,2-benzisoxazol-6-one (CP-126,998) shows promising results. The demethylated form of this ligand (CP-118,954) is a more potent and selective inhibitor than CP-126,998. In this study, therefore, CP-118,954 was labelled with F and evaluated for the in vivo mapping of AChE. METHODS The 4-fluoro (1). and 2-fluoro (2). derivatives of CP-118,954 were synthesized from 4-methyl-3-nitroanisole in 11 steps. Their in vitro binding affinities to AChE were measured using Ellman's method. The preparation of [F]-1 was carried out by reductive alkylation of the piperidine precursor with 4-[F]-fluorobenzaldehyde, followed by high-performance liquid chromatography (HPLC) purification. In vitro autoradiography was performed by incubating rat brain coronal slices with [F]-1. Tissue distribution studies were performed in mouse brain and the data were expressed as the percentage of the injected dose per gram of tissue (%ID x g). RESULTS Two fluorine-substituted AChE inhibitors were synthesized and their in vitro binding data showed that the 4-fluoro and 2-fluoro derivatives (1 and 2) had similar or superior binding affinity to that of the unsubstituted ligand, CP-118,954. The F-labelled ligand was synthesized in 20-35% radiochemical yield (EOS) and with high effective specific activity (36-42 GBq x micromol). Autoradiography showed high uptake of [F]-1 in the striatum and this striatal uptake was completely inhibited by the unlabelled ligand 1. Tissue distribution studies demonstrated that high radioactivity was accumulated in the striatum, an AChE-rich region. CONCLUSIONS This study demonstrates that [F]-1 may hold promise as a radioligand for the in vivo mapping of AChE.
Collapse
Affiliation(s)
- Sang-Yoon Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Abstract
Clinical applications of PET studies for dementia are reviewed in this paper. At the mild and moderate stages of Alzheimer's disease (AD), glucose metabolism is reduced not only in the parietotemporal region but also in the posterior cingulate and precuneus. At the advanced stage of AD, there is also a metabolic reduction in the frontal region. In AD patients, glucose metabolism is relatively preserved in the pons, sensorimotor cortices, primary visual cortices, basal ganglia, thalamus and cerebellum. In patients with dementia with Lewy bodies, glucose metabolism in the primary visual cortices is reduced, and this reduction appears to be associated with the reduction pattern in AD patients. In patients with frontotemporal dementia, reduced metabolism in the frontotemporal region is the main feature of this disease, but reduced metabolism in the basal ganglia, and/or parietal metabolic reduction can be associated with the frontotemporal reduction. When corticobasal degeneration is associated with dementia, the reduction pattern of dementia is similar to the reduction pattern in AD and the hallmarks of diagnosing corticobasal degeneration associated with dementia are a reduced metabolism in the primary sensorimotor region and/or basal ganglia and an asymmetric reduction in the two hemispheres. FDG-PET is a very useful tool for the diagnosis of early AD and for the differential diagnosis of dementia. I also describe clinical applications of PET for the diagnosis of dementia in Japan.
Collapse
Affiliation(s)
- Kazunari Ishii
- Department of Radiology and Nuclear Medicine, Hyogo Brain and Heart Center, Himeji, Japan.
| |
Collapse
|