Monoaminergic Degeneration and Ocular Motor Abnormalities in De Novo Parkinson's Disease

BACKGROUND

Evaluating eye movements in Parkinson's disease (PD) provides valuable insights into the underlying pathophysiological changes.

OBJECTIVE

The aim was to investigate the relationship between monoaminergic degeneration and ocular motor abnormalities in de novo PD.

METHODS

Drug-naive PD patients who underwent N-(3-[18 F]fluoropropyl)-2-carbomethoxy-3-(4-iodophenyl) nortropane positron emission tomography scans and video-oculography at diagnosis were eligible. Measurements of saccadic accuracy, latency, and smooth pursuit gain and square wave jerk frequency were collected. Patients underwent Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) and detailed cognitive tests. We investigated the associations between ocular motor measurements and specific tracer uptake ratios (SUR) in the caudate nucleus, anterior and posterior putamen, thalamus, and dorsal raphe nuclei, along with motor and cognitive symptoms.

RESULTS

One-hundred twenty-four subjects were included in this study. Saccadic accuracy was positively associated with parkinsonian motor severity expressed as Hoehn and Yahr stages, MDS-UPDRS Part III scores, and subscores for bradykinesia and rigidity but not with tremor scores (PFDR  < 0.05). Saccadic accuracy correlated with poor performances in the Rey-Complex-Figure copy, and latency with the Digit Symbol Coding and the Montreal Cognitive Assessment scores (PFDR  < 0.05). Prolonged saccadic latency correlated with reduced thalamic SUR, whereas decreased saccadic accuracy correlated with reduced SUR in the anterior and posterior putamen (PFDR  < 0.05). Reduced smooth pursuit gain showed associations with reduced SUR in the dorsal raphe, a serotonin-predominant region, but did not correlate with parkinsonism severity scores.

CONCLUSION

Defective dopaminergic and nondopaminergic neural systems may discretely influence ocular motor function in de novo PD patients. © 2023 International Parkinson and Movement Disorder Society.

Brain olfactory-related atrophy in isolated rapid eye movement sleep behavior disorder

OBJECTIVE

To investigate structural and functional connectivity changes in brain olfactory-related structures in a longitudinal prospective cohort of isolated REM sleep behavior disorder (iRBD) and their clinical correlations, longitudinal evolution, and predictive values for phenoconversion to overt synucleinopathies, especially Lewy body diseases.

METHODS

The cohort included polysomnography-confirmed iRBD patients and controls. Participants underwent baseline assessments including olfactory tests, neuropsychological evaluations, the Movement Disorders Society-Unified Parkinson's Disease Rating Scale, 3T brain MRI, and 18 F-FP-CIT PET scans. Voxel-based morphometry (VBM) was performed to identify regions of atrophy in iRBD, and volumes of relevant olfactory-related regions of interest (ROI) were estimated. Subgroups of patients underwent repeated volumetric MRI and resting-state functional MRI (fMRI) scans after four years.

RESULTS

A total of 51 iRBD patients were included, with 20 of them converting to synucleinopathy (mean time to conversion 3.08 years). Baseline VBM analysis revealed atrophy in the right olfactory cortex and gyrus rectus in iRBD. Subsequent ROI comparisons with controls showed atrophy in the amygdala. These olfactory-related atrophies tended to be associated with worse depression, anxiety, and urinary problems in iRBD. Amygdala 18 F-FP-CIT uptake tended to be reduced in iRBD patients with hyposmia (nonsignificant after multiple comparison correction) and correlated with urinary problems. Resting-state fMRI of 23 patients and 32 controls revealed multiple clusters with aberrant olfactory-related functional connectivity. Hypoconnectivity between the putamen and olfactory cortex was associated with mild parkinsonian signs in iRBD. Longitudinal analysis of volumetric volumetric MRI in 22 iRBD patients demonstrated four-year progression of olfactory-related atrophy. Cox regression analysis revealed that this atrophy significantly predicted phenoconversion.

INTERPRETATION

Progressive atrophy of central olfactory structures may be a potential indicator of Lewy body disease progression in iRBD.

Longitudinal evolution of cortical thickness signature reflecting Lewy body dementia in isolated REM sleep behavior disorder: a prospective cohort study

BACKGROUND

The isolated rapid-eye-movement sleep behavior disorder (iRBD) is a prodromal condition of Lewy body disease including Parkinson's disease and dementia with Lewy bodies (DLB). We aim to investigate the longitudinal evolution of DLB-related cortical thickness signature in a prospective iRBD cohort and evaluate the possible predictive value of the cortical signature index in predicting dementia-first phenoconversion in individuals with iRBD.

METHODS

We enrolled 22 DLB patients, 44 healthy controls, and 50 video polysomnography-proven iRBD patients. Participants underwent 3-T magnetic resonance imaging (MRI) and clinical/neuropsychological evaluations. We characterized DLB-related whole-brain cortical thickness spatial covariance pattern (DLB-pattern) using scaled subprofile model of principal components analysis that best differentiated DLB patients from age-matched controls. We analyzed clinical and neuropsychological correlates of the DLB-pattern expression scores and the mean values of the whole-brain cortical thickness in DLB and iRBD patients. With repeated MRI data during the follow-up in our prospective iRBD cohort, we investigated the longitudinal evolution of the cortical thickness signature toward Lewy body dementia. Finally, we analyzed the potential predictive value of cortical thickness signature as a biomarker of phenoconversion in iRBD cohort.

RESULTS

The DLB-pattern was characterized by thinning of the temporal, orbitofrontal, and insular cortices and relative preservation of the precentral and inferior parietal cortices. The DLB-pattern expression scores correlated with attentional and frontal executive dysfunction (Trail Making Test-A and B: R = - 0.55, P = 0.024 and R = - 0.56, P = 0.036, respectively) as well as visuospatial impairment (Rey-figure copy test: R = - 0.54, P = 0.0047). The longitudinal trajectory of DLB-pattern revealed an increasing pattern above the cut-off in the dementia-first phenoconverters (Pearson's correlation, R = 0.74, P = 6.8 × 10^-4) but no significant change in parkinsonism-first phenoconverters (R = 0.0063, P = 0.98). The mean value of the whole-brain cortical thickness predicted phenoconversion in iRBD patients with hazard ratio of 9.33 [1.16-74.12]. The increase in DLB-pattern expression score discriminated dementia-first from parkinsonism-first phenoconversions with 88.2% accuracy.

CONCLUSION

Cortical thickness signature can effectively reflect the longitudinal evolution of Lewy body dementia in the iRBD population. Replication studies would further validate the utility of this imaging marker in iRBD.

Mild behavioral impairment linked to progression to Alzheimer's disease and cortical thinning in amnestic mild cognitive impairment

Background

Mild behavioral impairment (MBI) is a neurobehavioral syndrome characterized by later life emergence of sustained neuropsychiatric symptoms, as an at-risk state for dementia. However, the associations between MBI and a risk of progression to Alzheimer's disease (AD) and its neuroanatomical correlates in mild cognitive impairment (MCI) are still unclear.

Method

A total 1,184 older adults with amnestic MCI was followed for a mean of 3.1 ± 2.0 years. MBI was approximated using a transformation algorithm for the Neuropsychiatric Inventory at baseline. A two-step cluster analysis was used to identify subgroups of individuals with amnestic MCI based on profiles of 5 MBI domain symptoms (decreased motivation, affective dysregulation, impulse dyscontrol, social inappropriateness, abnormal perception/thought content). A Cox regression analysis was applied to investigate differences in the risk of progression to AD between subgroups. A subset of participants (n = 202) underwent 3D T1-weighted MRI scans at baseline and cortical thickness was compared between the subgroups of amnestic MCI patients.

Result

The cluster analysis classified the patients into 3 groups: (1) patients without any MBI domain symptoms (47.4%, asymptomatic group); (2) those with only affective dysregulation (29.4%, affective dysregulation group); (3) those with multiple MBI domain symptoms, particularly affective dysregulation, decreased motivation and impulse dyscontrol (23.2%, complex group). Compared to the asymptomatic group, the complex group was associated with a higher risk of progression to AD (hazard ratio = 2.541 [1.904-3.392], p < 0.001), but the affective dysregulation group was not (1.214 [0.883-1.670], p = 0.232). In cortical thickness analysis, the complex group revealed cortical thinning bilaterally in the inferior parietal, lateral occipital, lateral superior temporal, and frontopolar regions compared with the affective dysregulation group.

Conclusion

The multiple co-occuring MBI domains in individuals with amnestic MCI are associated with a higher risk of progression to AD and cortical thinning in temporal, parietal and frontal areas. These results suggest that evaluation of MBI could be useful for risk stratification for AD and appropriate intervention in MCI individuals.

Brain Metabolism Related to Mild Cognitive Impairment and Phenoconversion in Patients With Isolated REM Sleep Behavior Disorder

Background and Objectives

Mild cognitive impairment (MCI) in isolated REM sleep behavior disorder (iRBD) is a risk factor for subsequent neurodegeneration. We aimed to identify brain metabolism and functional connectivity changes related to MCI in patients with iRBD and the neuroimaging markers' predictive value for phenoconversion.

Methods

This is a prospective cohort study of patients with iRBD with a mean follow-up of 4.2 ± 2.6 years. At baseline, patients with iRBD and age- and sex-matched healthy controls (HCs) underwent ¹⁸F-fluorodeoxyglucose (FDG)–PET and resting-state fMRI scans and a comprehensive neuropsychological test battery. Voxel-wise group comparisons for FDG-PET data were performed using a general linear model. Seed-based connectivity maps were computed using brain regions showing significant hypometabolism associated with MCI in patients with iRBD and compared between groups. A Cox regression analysis was applied to investigate the association between brain metabolism and risk of phenoconversion.

Results

Forty patients with iRBD, including 21 with MCI (iRBD-MCI) and 19 with normal cognition (iRBD-NC), and 24 HCs were included in the study. The iRBD-MCI group revealed relative hypometabolism in the inferior parietal lobule, lateral and medial occipital, and middle and inferior temporal cortex bilaterally compared with HC and the iRBD-NC group. In seed-based connectivity analyses, the iRBD-MCI group exhibited decreased functional connectivity of the left angular gyrus with the occipital cortex. Of 40 patients with iRBD, 12 patients converted to Parkinson disease (PD) or dementia with Lewy bodies (DLB). Hypometabolism of the occipital pole (hazard ratio [95% CI] 6.652 [1.387–31.987]), medial occipital (4.450 [1.143–17.327]), and precuneus (3.635 [1.009–13.093]) was associated with higher phenoconversion rate to PD/DLB.

Discussion

MCI in iRBD is related to functional and metabolic changes in broad brain areas, particularly the occipital and parietal areas. Moreover, hypometabolism in these brain regions was a predictor of phenoconversion to PD or DLB. Evaluation of cognitive function and neuroimaging characteristics could be useful for risk stratification in patients with iRBD.

Parkinson Disease-Related Brain Metabolic Patterns and Neurodegeneration in Isolated REM Sleep Behavior Disorder

OBJECTIVE

To elucidate the role of Parkinson disease (PD)-related brain metabolic patterns as a biomarker in isolated REM sleep behavior disorder (iRBD) for future disease conversion.

METHODS

This is a prospective cohort study consisting of 30 patients with iRBD, 25 patients with de novo PD with a premorbid history of RBD, 21 patients with longstanding PD on stable treatment, and 24 healthy controls. The iRBD group was longitudinally followed up. All participants underwent ¹⁸F-fluorodeoxyglucose (FDG) PET and were evaluated with olfaction, cognition, and the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) at baseline. From FDG-PET scans, we derived metabolic patterns from the longstanding PD group (PD-RP) and de novo PD group with RBD (dnPDRBD-RP). Subsequently, we calculated the PD-RP and dnPDRBD-RP scores in patients with iRBD. We validated the metabolic patterns in each PD group and separate iRBD cohort (n = 14).

RESULTS

The 2 patterns significantly correlated with each other and were spatially overlapping yet distinct. The MDS-UPDRS motor scores significantly correlated with PD-RP (p = 0.013) but not with dnPDRBD-RP (p = 0.076). In contrast, dnPDRBD-RP correlated with olfaction in butanol threshold test (p = 0.018) in patients with iRBD, but PD-RP did not (p = 0.21). High dnPDRBD-RP in patients with iRBD predicted future phenoconversion with all cutoff ranges from 1.5 to 3 SD of the control value, whereas predictability of PD-RP was only significant in a partial range of cutoff.

CONCLUSION

The dnPDRBD-RP is an efficient neuroimaging biomarker that reflects prodromal features of PD and predicts phenoconversion in iRBD that can be applied individually.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that a de novo PD pattern on FDG-PET predicts future conversion to neurodegenerative disease in patients with iRBD.

Longitudinal Changes in Isolated Rapid Eye Movement Sleep Behavior Disorder-Related Metabolic Pattern Expression

BACKGROUND

It remains unclear whether and how the isolated rapid eye movement (REM) sleep behavior disorder (iRBD)-related metabolic pattern (RBDRP) changes with disease progression in iRBD.

OBJECTIVE

To examine longitudinal changes in RBDRP expression in iRBD patients and to explore trajectories of relative metabolic activities of individual brain regions constituting RBDRP.

METHODS

In this cohort study, 25 iRBD patients (mean age [±standard deviation], 69.2 ± 5.3 years; 12 [48%] patients were men) and 24 age-matched healthy controls were included. The patients underwent at least two ¹⁸ F-fluorodeoxyglucose positron emission tomography scans at baseline and at the 2-year and/or 4-year follow-ups. We measured the RBDRP expression of the patients and controls which was validated by reproduction in a separate iRBD cohort (n = 13).

RESULTS

At baseline, the RBDRP expression discriminated iRBD patients from healthy controls. However, the RBDRP expression z scores tended to decrease over time in the patients, especially with longer follow-ups, and this tendency was observed even in patients with high-risk of phenoconversion. Furthermore, the degree of RBDRP expression at baseline did not predict the disease conversion. The RBDRP breakdown was mainly provoked by the attenuation of relative hypermetabolism in the frontal cortex including premotor areas and relative hypometabolism in the occipital cortex. The putaminal metabolic activity increased steadily with the disease progression.

CONCLUSIONS

The RBDRP expression in iRBD patients was altered significantly over time. Some of the brain metabolic changes seem to represent attempted functional compensation against ongoing neurodegeneration. The RBDRP expression measurement at one time point may not be a reliable biomarker for predicting disease conversion. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Probable REM sleep behavior disorder is associated with longitudinal cortical thinning in Parkinson's disease

REM sleep behavior disorder (RBD) has a poor prognostic implication in both motor and non-motor functions in Parkinson’s disease (PD) patients. However, to the best of our knowledge no study to date investigated the longitudinal cerebral changes underlying RBD symptoms in PD. We performed the longitudinal study to investigate the association between probable RBD and cortical and subcortical changes in early, de novo PD patients. We studied 78 participants from the Parkinson’s Progression Marker Initiative who underwent structural MRI at baseline and after 2 years. The presence of probable RBD (pRBD) was evaluated using the RBD screening questionnaire. We compared the cross-sectional and longitudinal cortical thickness and subcortical volume changes, between PD patients with and without pRBD. At baseline, we found bilateral inferior temporal cortex thinning in the PD-pRBD group compared with the PD-noRBD group. Longitudinally, the PD-pRBD group revealed a significant increase in the rate of thinning in the left insula compared with the PD-noRBD group, and the increased thinning correlated with decreased cognitive performance. In subcortical volume analyses, the presence of pRBD was linked with volume decrease over time in the left caudate nucleus, pallidum and amygdala. The volume changes in the left caudate nucleus revealed correlations with global cognition. These results support the idea that RBD is an important marker of rapid progression in PD motor and non-motor symptoms and suggest that the atrophy in the left insula and caudate nucleus might be the underlying neurobiological mechanisms of the poorer prognosis in PD patients with RBD.

Patterns of brain activity during a set-shifting task linked to mild behavioral impairment in Parkinson's disease

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PD with mild behavioral impairment revealed deficits in cognitive flexibility.

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Brain activities during a set-shifting task linked with MBI in PD was evaluated.

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PD-MBI revealed reduced activity in the prefrontal and posterior parietal cortices.

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The prefrontal activity was associated with cognitive impairment in PD-MBI.

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High MBI-C score was associated with reduced deactivation in the hippocampus.

Mild behavioral impairment (MBI) is a neurobehavioral syndrome characterized by later life emergence of sustained neuropsychiatric symptoms, as an at-risk state for incident cognitive decline and dementia. Prior studies have reported that neuropsychiatric symptoms are associated with cognitive abilities in Parkinson’s disease (PD) patients, and we have recently found a strong correlation between MBI and cognitive performance. However, the underlying neural activity patterns of cognitive performance linked to MBI in PD are unknown. Fifty-nine non-demented PD patients and 26 healthy controls were scanned using fMRI during performance of a modified version of the Wisconsin card sorting task. MBI was evaluated using the MBI-checklist, and PD patients were divided into two groups, PD-MBI and PD-noMBI. Compared to the PD-noMBI group and healthy controls, the PD-MBI group revealed less activation in the prefrontal and posterior parietal cortices, and reduced deactivation in the medial temporal region. These results suggest that in PD, MBI reflects deficits in the frontoparietal control network and the hippocampal memory system.

Theta-Burst Stimulation for Cognitive Enhancement in Parkinson's Disease With Mild Cognitive Impairment: A Randomized, Double-Blind, Sham-Controlled Trial

Background: Mild cognitive impairment is a common non-motor symptom of Parkinson's disease (PD-MCI) and has minimal treatment options.

Objective: In this double-blind, randomized, sham-controlled trial, we assessed the effect of repeated sessions of intermittent theta-burst stimulation over the left dorsolateral prefrontal cortex on cognition and brain connectivity in subjects with PD-MCI.

Methods: Forty-one subjects were randomized to receive real (n = 21) or sham stimulation (n = 20). All subjects underwent neuropsychological assessments before, 1 day, and 1 month after stimulation. Subjects also underwent resting-state functional magnetic resonance imaging before and 48 h after stimulation. The primary outcome was the change in the cognitive domain (executive function, attention, memory, language, and visuospatial abilities) z-scores across time.

Results: There was an insignificant effect on cognitive domain z-scores across time when comparing real with sham stimulation and correcting for multiple comparisons across cognitive domains (p > 0.05 Bonferroni correction). However, the real stimulation group demonstrated a trend toward improved executive functioning scores at the 1-month follow-up compared with sham (p < 0.05 uncorrected). After real stimulation, the connectivity of the stimulation site showed decreased connectivity to the left caudate head. There was no change in connectivity within or between the stimulation network (a network of cortical regions connected to the stimulation site) and the striatal network. However, higher baseline connectivity between the stimulation network and the striatal network was associated with improved executive function scores at 1 month.

Conclusions: These results suggest that intermittent theta-burst stimulation over the dorsolateral prefrontal cortex in subjects with PD-MCI has minimal effect on cognition compared with sham, although there were trends toward improved executive function. This intervention may be more effective in subjects with higher baseline connectivity between the stimulation network and the striatal network. This trial supports further investigation focusing on executive function and incorporating connectivity-based targeting.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT03243214.

Mild behavioral impairment in Parkinson's disease is associated with altered corticostriatal connectivity

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Mild behavioral impairment in PD is linked to altered corticostriatal connectivity.

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PD-MBI have less connectivity between the striatum and the DMN.

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PD-MBI have increased atrophy of the SAN.

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Caudate head and dorsal putamen connectivity is related to MBI-C scores in PD.

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Caudate head-precuneus connectivity is linked to both MBI and MoCA scores.

Background

Mild behavioral impairment (MBI) is a syndrome characterized by later life onset, sustained neuropsychiatric symptoms as a marker of dementia risk. In Parkinson's disease (PD), MBI has been associated with worse cognitive abilities and increased cortical atrophy. However, the circuit level correlates of MBI have not been investigated in this population. Our objective was to investigate the relationship between MBI and corticostriatal connectivity in PD patients. This emphasis on corticostriatal connectivity was due to the significant role of these circuits in neuropsychiatric and cognitive symptoms across disease conditions.

Methods

Seventy-four non-demented patients with PD were administered the MBI-checklist, and classified as having high MBI (PD-MBI; n = 21) or low MBI scores (PD-noMBI; n = 53). Corticostriatal connectivity was assessed with both an atlas and seed-based analysis. The atlas analysis consisted of calculating the average connectivity between the striatal network and the default mode (DMN), central executive (CEN), and saliency networks (SAN). Structural measurements of cortical thickness and volume were also assessed. PD-MBI and PD-noMBI patients were compared, along with a group of age matched healthy control subjects (HC; n = 28). Subsequently, a seed analysis assessed the relationship of MBI scores with the connectivity of twelve seeds within the striatum while controlling for cognitive ability. A complementary analysis assessed the relationship between striatal connectivity and cognition, while controlling for MBI-C.

Results

PD-MBI demonstrated decreased connectivity between the striatum and both the DMN and SAN compared to PD-noMBI and HC. The decreased connectivity between the striatum and the SAN was explained partly by increased atrophy within the SAN in PD-MBI. The seed analysis revealed a relationship between higher MBI scores and lower connectivity of the left caudate head to the dorsal anterior cingulate cortex and left middle frontal gyrus. Higher MBI-C scores were also related to decreased connectivity of the right caudate head with the anterior cingulate cortex, precuneus, and left supramarginal gyrus, as well as increased connectivity to the left hippocampus and right cerebellar hemisphere. Caudate-precuneus connectivity was independently associated with both global behavioural and cognitive scores.

Conclusion

These results suggest PD-MBI is associated with altered corticostriatal connectivity, particularly between the head of the caudate and cortical regions associated with the DMN and SAN. In particular, caudate-precuneus connectivity is associated with both global behavioral and cognitive symptoms in PD.

Macular ganglion-cell-complex layer thinning and optic nerve integrity in drug-naïve Parkinson's disease

To reveal the macular inner retinal change linked to axonal degeneration in Parkinson's disease (PD), we performed macular optical coherence tomography scan and diffusion tensor imaging of the retrobulbar optic nerve on both eyes of 36 drug-naïve PD patients. Thicknesses of inner retinal layers were automatically measured, and correlation analysis was conducted between the retinal thickness and diffusion parameters of the optic nerve. PD patients showed thinning of the inner retinal layers compared to control data. Thicknesses of the ganglion cell and inner plexiform layers were both correlated positively with fractional anisotropy and negatively with diffusivity indices of ipsilateral optic nerve (FDR-adjusted p < 0.05). This study revealed a novel in vivo connection between macular parafoveal ganglion cell change and integrity in the retrobulbar optic nerve in drug-naïve PD.

Mild behavioral impairment is linked to worse cognition and brain atrophy in Parkinson disease

OBJECTIVE

To evaluate the associations of mild behavioral impairment (MBI) with cognitive deficits and patterns of gray matter changes in Parkinson disease (PD).

METHODS

Sixty patients with PD without dementia and 29 healthy controls underwent a cognitive neuropsychological evaluation and structural MRI scan. MBI was evaluated with the MBI Checklist (MBI-C), a rating scale designed to elicit emergent neuropsychiatric symptoms in accordance with MBI criteria. We divided the patients with PD into 2 groups: 1 group with high MBI-C scores (PD-MBI) and the other with low MBI-C scores (PD-noMBI).

RESULTS

Among 60 patients with PD, 20 were categorized as having PD-MBI (33.33%). In healthy controls, no participants met the MBI cut-point threshold. The PD-MBI group had significantly lower Montreal Cognitive Assessment and z scores in all 5 domains and the global score compared to healthy controls and those with PD-noMBI. In addition, all cognitive domains except language and global cognition negatively correlated with the MBI-C total score in all patients with PD. For cortical structures, the PD-MBI group revealed middle temporal cortex thinning and decreased volume compared with the PD-noMBI group, and decreased volume in this area negatively correlated with the MBI-C total score.

CONCLUSIONS

The impaired cognitive function over all domains and atrophy in the temporal area in the PD-MBI group are in line with posterior cortical circuit deficits in PD, which have been associated with a faster rate of progression to dementia. These initial results suggest that MBI might be an early and important marker for incident cognitive decline and dementia in patients with PD.

Nonmotor and Dopamine Transporter Change in REM Sleep Behavior Disorder by Olfactory Impairment

Objective

It is unclear whether the decline in dopamine transporters (DAT) differs among idiopathic rapid eye movement sleep behavior disorder (iRBD) patients with different levels of olfactory impairment. This study aimed to characterize DAT changes in relation to nonmotor features in iRBD patients by olfactory loss.

Methods

This prospective cohort study consisted of three age-matched groups: 30 polysomnography-confirmed iRBD patients, 30 drug-naïve Parkinson’s disease patients, and 19 healthy controls without olfactory impairment. The iRBD group was divided into two groups based on olfactory testing results. Participants were evaluated for reported prodromal markers and then underwent ¹⁸F-FP-CIT positron emission tomography and 3T MRI. Tracer uptakes were analyzed in the caudate, anterior and posterior putamen, substantia nigra, and raphe nuclei.

Results

Olfactory impairment was defined in 38.5% of iRBD patients. Mild parkinsonian signs and cognitive functions were not different between the two iRBD subgroups; however, additional prodromal features, constipation, and urinary and sexual dysfunctions were found in iRBD patients with olfactory impairment but not in those without. Tracer uptake showed significant group differences in all brain regions, except the raphe nuclei. The iRBD patients with olfactory impairment had uptake reductions in the anterior and posterior putamen, caudate, and substantia nigra (p < 0.016 in all, adjusted for age), which ranged from 0.6 to 0.8 of age-normative values. In contrast, those without olfactory impairment had insignificant changes in all regions ranging above 0.8.

Conclusion

There was a clear distinction in DAT loss and nonmotor profiles by olfactory status in iRBD.

Efficacy of Cilostazol Administration in Alzheimer's Disease Patients with White Matter Lesions: A Positron-Emission Tomography Study

This study tested the efficacy of the phosphodiesterase type III inhibitor cilostazol in Alzheimer's disease patients with white matter lesions treated with donepezil in comparison with donepezil monotherapy using fluorodeoxyglucose (18F) positron-emission tomography (FDG PET). A 24-week, randomized, double-blind, placebo-controlled, parallel-group study was conducted. Thirty-six Alzheimer's disease patients with white matter lesions who received donepezil (n = 18 each in the cilostazol and placebo groups) were enrolled. Participants underwent pre and post FDG PET imaging scans and three rounds of clinical and neuropsychological tests. The cilostazol group did not show a significant decrease of regional glucose metabolism; however, regional glucose metabolism was significantly decreased in the parietal and frontal lobes of the placebo group. The repeated measures ANOVA measuring differences in uptake change revealed that regional glucose metabolism in the left inferior frontal gyrus was significantly more preserved in the cilostazol group than that in the placebo group (p < 0.005). Mean changes from baseline on the Mini-Mental State Exam, Alzheimer's Disease Assessment Scale-cognitive subscale, Alzheimer's Disease Cooperative Study-Activities of Daily Living Inventory, and the Clinical Dementia Rating Sum of Boxes did not differ between the two groups. In the cilostazol group, the increase of glucose metabolism correlated with the improvment of the Alzheimer's Disease Assessment Scale-cognitive score. We conclude that cilostazol treatment added to donepezil may delay the decline in regional cerebral metabolism in Alzheimer's disease with white matter lesions compared with donepezil monotherapy. In additon, our results verified the efficacy of cilostazol in improving or protecting cognitive function in Alzheimer's disease through increased glucose metabolism. However, the long-term effect of cilostazol on cognitive function and Alzheimer's disease modification must be tested in further studies with larger sample size and longer study period. Trial registration: http://clinicaltrials.gov : NCT01409564.

A New Metabolic Network Correlated with Olfactory and Executive Dysfunctions in Idiopathic Rapid Eye Movement Sleep Behavior Disorder

Background and Purpose

To identify a metabolic network reflecting neurodegeneration in patients with idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD).

Methods

We recruited a prospective cohort comprising patients with de novo Parkinson's disease (PD) with probable REM sleep behavior disorder (PDRBD, n=21), polysomnography-confirmed iRBD patients (n=28), and age-matched healthy controls (HC) (n=24). PDRBD-related spatial covariance pattern (PDRBD-RP) were determined from ¹⁸F-fluorodeoxyglucose PET images of the PDRBD group and validated by reproduction in a separate PD cohort with polysomnography-confirmed REM sleep behavior disorder (n=11). We also confirmed via ¹⁸F-N-3-fluoropropyl-2β-carboxymethoxy-3β-(4-iodophenyl)-nortropane PET that none of our iRBD patients had any loss of dopamine transporters (DATs) suggestive of PD. Differences in the PDRBD-RP across groups were compared, and the clinical significance of these metabolic patterns in iRBD patients was further evaluated based on relationships with olfactory and cognitive functions, and striatal DAT densities.

Results

The PDRBD-RP reflected the previously reported PD-related covariance pattern and additionally showed relative metabolic increases in the hippocampus and premotor cortex. The PDRBD-RP gradually increased from the HC to iRBD patients and to the de novo and validation PDRBD groups. In iRBD patients, the PDRBD-RP was negatively correlated with olfactory and frontal executive functions (age-controlled p<0.01 for both), and tended to be negatively correlated with the striatal DAT density, although this was insignificant after age adjustment. During the mean follow-up period of 3.5 years, 5 of 11 iRBD patients with PDRBD-RP elevation had developed Lewy body diseases, whereas those without PDRBD-RP elevation had not.

Conclusions

Our results suggest that PDRBD-RP is an effective biomarker for monitoring the progression to neurodegenerative disease in iRBD patients.

Retinal thinning associates with nigral dopaminergic loss in de novo Parkinson disease

OBJECTIVE

To analyze the relationship between retinal thinning and nigral dopaminergic loss in de novo Parkinson disease (PD).

METHODS

Forty-nine patients with PD and 54 age-matched controls were analyzed. Ophthalmologic examination and macula optical coherence tomography scans were performed with additional microperimetry, N-(3-[¹⁸F]fluoropropyl)-2-carbomethoxy-3-(4-iodophenyl) nortropane PET, and 3T MRI scans were done in patients with PD only. Retinal layer thickness and volume were measured in subfields of the 1-, 2.22-, and 3.45-mm Early Treatment of Diabetic Retinopathy Study circle and compared in patients with PD and controls. Correlation of inner retinal layer thinning with microperimetric response was examined in patients with PD, and the relationships between retinal layer thickness and dopamine transporter densities in the ipsilateral caudate, anterior and posterior putamen, and substantia nigra were analyzed.

RESULTS

Retinal layer thinning was observed in the temporal and inferior 2.22-mm sectors (false discovery rate-adjusted p < 0.05) of drug-naive patients with PD, particularly the inner plexiform and ganglion cell layers. The thickness of these layers in the inferior 2.22-mm sector showed a negative correlation with the Hoehn and Yahr stage (p = 0.032 and 0.014, respectively). There was positive correlation between macular sensitivity and retinal layer thickness in all 3.45-mm sectors, the superior 2.22-mm sector, and 1-mm circle (p < 0.05 for all). There was an association between retinal thinning and dopaminergic loss in the left substantia nigra (false discovery rate-adjusted p < 0.001).

CONCLUSION

Retinal thinning is present in the early stages of PD, correlates with disease severity, and may be linked to nigral dopaminergic degeneration. Retinal imaging may be useful for detection of pathologic changes occurring in early PD.

Visual Hallucination and Pattern of Brain Degeneration in Parkinson's Disease

BACKGROUND AND OBJECTIVES

The incidence of visual hallucination (VH) increases with Parkinson's disease (PD) progression, and its development is thought to be related to a specific neurodegenerative process in PD. This study aimed to reveal brain degeneration related to VH in PD by analyzing neuroimaging data obtained from patients in their different stages of PD.

METHODS

Data from 48 PD patients - 21 nondemented without VH (PNV group), 10 nondemented with VH (PV group), and 17 demented with VH (PVD group) - and 30 age-matched healthy controls (HC group) were analyzed. Voxel-based morphometry and tract-based spatial statistics were conducted. Previous magnetic resonance volumetric studies on VH in PD were collectively reviewed.

RESULTS

The PV group showed gray matter atrophy in the right inferior parietal lobule and supramarginal gyrus compared with the HC and PNV groups. The PVD group showed a wider range of gray matter atrophies in the temporo-parieto-occipital regions than those in the PV group. White matter changes seemed to be an earlier event than gray matter changes. Fractional anisotropy values diffusely decreased in all three PD subgroups compared with the HC group without significant differences between the PD subgroups. Mean diffusivity was not different between the PNV and HC groups but increased in the parieto-temporal region in the PV group and increased diffusely in the PVD group, additionally including the fronto-occipital regions. A review of previous studies supported our observations.

CONCLUSIONS

Gray matter degenerations from the parieto-temporal junction to the parieto-occipital and temporo-occipital regions may be responsible for VH on the typical timeline of PD progression.

Association of Cerebral Amyloidosis, Blood Pressure, and Neuronal Injury with Late-Life Onset Depression

Previous literature suggests that Alzheimer's disease (AD) process may contribute to late-life onset depression (LLOD). Therefore, we investigated the association of LLOD with cerebral amyloidosis and neuronal injury, the two key brain changes in AD, along with vascular risks. Twenty nine non-demented individuals who first experienced major depressive disorder (MDD) after age of 60 years were included as LLOD subjects, and 27 non-demented elderly individuals without lifetime experience of MDD were included as normal controls (NC). Comorbid mild cognitive impairment (MCI) was diagnosed in 48% of LLOD subjects and in 0% of NC. LLOD, irrespective of comorbid MCI diagnosis, was associated with prominent prefrontal cortical atrophy. Compared to NC, LLOD subjects with comorbid MCI (LLOD_MCI) showed increased cerebral ¹¹C-Pittsburg compound B (PiB) retention and plasma beta-amyloid 1–40 and 1–42 peptides, as measures of cerebral amyloidosis; and, such relationship was not observed in overall LLOD or LLOD without MCI (LLOD_woMCI). LLOD subjects, particularly the LLOD_woMCI, had higher systolic blood pressure (SBP) than NC. When analyzed in the same multiple logistic regression model that included prefrontal gray matter (GM) density, cerebral amyloidosis, and SBP as independent variables, only prefrontal GM density showed a significant independent association with LLOD regardless of MCI comorbidity status. Our findings suggest AD process might be related to LLOD via prefrontal neuronal injury in the MCI stage, whereas vascular processes—SBP elevation, in particular—are associated with LLOD via prefrontal neuronal injury even in cognitively intact or less impaired individuals.

Association Between Serum Triglycerides and Cerebral Amyloidosis in Cognitively Normal Elderly

OBJECTIVES

Although many preclinical studies have suggested the possible linkage between dyslipidemia and cerebral amyloid deposition, the association between serum lipid measures and cerebral amyloid-beta (Aβ) deposition in human brain is still poorly known. We aimed to investigate the association in cognitively normal (CN) elderly individuals.

DESIGN

Cross-sectional study.

SETTING

University hospital dementia clinic.

PARTICIPANTS

59 CN elderly.

MEASUREMENTS

The study measures included comprehensive clinical and neuropsychological assessment based on the CERAD protocol, magnetic resonance imaging and (11)C-labelled Pittsburgh Compound B positron emission tomography scans, and quantification for serum lipid biomarkers.

RESULTS

Multiple linear regression analyses showed that a higher serum triglycerides level was associated with heavier global cerebral Aβ deposition even after controlling age, sex, and apolipoprotein E ε4 genotype. Serum apolipoprotein B also showed significant positive association with global cerebral Aβ deposition, but the significance disappeared after controlling serum triglycerides level. No association was found between other lipid measures and global cerebral Aβ deposition.

CONCLUSIONS

The findings suggest that serum triglycerides are closely associated with cerebral amyloidosis, although population-based prospective studies are needed to provide further evidence of the causative effect of triglycerides on cerebral amyloidosis.

Asymmetry of Dopamine D2/3 Receptor Availability in Dorsal Putamen and Body Mass Index in Non-obese Healthy Males

The dopaminergic system is involved in the regulation of food intake, which is crucial for the maintenance of body weight. We examined the relationship between striatal dopamine (DA) D2/3 receptor availability and body mass index (BMI) in 25 non-obese healthy male subjects using [¹¹C]raclopride and positron emission tomography. None of [¹¹C]raclopride binding potential (BP) values (measures of DA D2/3 receptor availability) in striatal subregions (dorsal caudate, dorsal putamen, and ventral striatum) in the left and right hemispheres was significantly correlated with BMI. However, there was a positive correlation between the right-left asymmetry index of [¹¹C]raclopride BP in the dorsal putamen and BMI (r=0.43, p<0.05), suggesting that greater BMI is linked with higher receptor availability in the right dorsal putamen relative to the left in non-obese individuals. The present results, combined with previous findings, may also suggest neurochemical mechanisms underlying the regulation of food intake in non-obese individuals.

Transcranial Direct Current Stimulation to Lessen Neuropathic Pain After Spinal Cord Injury

Background. It is suggested that transcranial direct current stimulation (tDCS) can produce lasting changes in corticospinal excitability and can potentially be used for the treatment of neuropathic pain. However, the detailed mechanisms underlying the effects of tDCS are unknown. Objective. We investigated the underlying neural mechanisms of tDCS for chronic pain relief using [18F]-fluorodeoxyglucose positron emission tomography ([18F]FDG-PET). Methods. Sixteen patients with neuropathic pain (mean age 44.1 ± 8.6 years, 4 females) due to traumatic spinal cord injury received sham or active anodal stimulation of the motor cortex using tDCS for 10 days (20 minutes, 2 mA, twice a day). The effect of tDCS on regional cerebral glucose metabolism was evaluated by [18F]FDG-PET before and after tDCS sessions. Results. There was a significant decrease in the numeric rating scale scores for pain, from 7.6 ± 0.5 at baseline to 5.9 ± 1.8 after active tDCS ( P = .016). We found increased metabolism in the medulla and decreased metabolism in the left dorsolateral prefrontal cortex after active tDCS treatment compared with the changes induced by sham tDCS. Additionally, an increase in metabolism after active tDCS was observed in the subgenual anterior cingulate cortex and insula. Conclusion. The results of this study suggest that anodal stimulation of the motor cortex using tDCS can modulate emotional and cognitive components of pain and normalize excessive attention to pain and pain-related information.

Central presentation of postviral olfactory loss evaluated by positron emission tomography scan: a pilot study

BACKGROUND

Postviral olfactory loss after upper respiratory tract infection (URI) is not uncommon. However, its exact location and nature are not fully understood. Although it is likely to be caused by a direct damage of olfactory epithelium, a damage of the central pathway has also been suspected as its possible mechanism. This study will show basal metabolism in the brain of patients with postviral olfactory loss using fluorodeoxyglucose-positron emission tomography (FDG PET).

METHODS

Nine patients with postviral olfactory dysfunction were enrolled. All of the patients had neither apparent sinusitis nor rhinitis. All of them recalled causative URI and temporal connection with development of their olfactory loss. After olfactory function tests using the butanol threshold test and smell identification test confirmed olfactory impairment, FDG PET studies were performed during a rest state. The cerebral metabolic abnormality was compared between the patients and age/gender-matched healthy controls using a voxel-wised analysis.

RESULTS

In comparison with healthy controls, the patients showed a significant hypometabolism in the right piriform cortex and bilateral amygdala and parahippocampal areas where the olfactory neurons primarily project. Furthermore, hypometabolism was also shown in the bilateral insular cortices, medial and lateral temporal cortex where the olfactory information is integrated to produce the sensation. Increased metabolism was not found in any brain area.

CONCLUSION

This study showed that the postviral olfactory loss is likely to be associated with decreased metabolism in the specific brain regions where the olfactory information is received and integrated.

Intracellular amyloid beta interacts with SOD1 and impairs the enzymatic activity of SOD1: implications for the pathogenesis of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by the degeneration of motor neurons. Mutations in Cu/Zn superoxide dismutase (SOD1), including G93A, were reportedly linked to familial ALS. SOD1 is a key antioxidant enzyme, and is also one of the major targets for oxidative damage in the brains of patients suffering from Alzheimers disease (AD). Several lines of evidence suggest that intracellular amyloid beta (Abeta) is associated with the pathogenesis of AD. In this report we demonstrate that intracellular Abeta directly interacts with SOD1, and that this interaction decreases the enzymatic activity of the enzyme. We observed Abeta-SOD1 aggregates in the perinuclear region of H4 cells, and mapped the SOD1 binding region to Abeta amino acids 26-42. Interestingly, intracellular Ab binds to the SOD1 G93A mutant with greater affinity than to wild-type SOD1. This resulted in considerably less mutant enzymatic activity. Our study implicates a potential role for Abeta in the development of ALS by interacting with the SOD1 G93A mutant.

Beta-amyloid precursor protein is a direct cleavage target of HtrA2 serine protease. Implications for the physiological function of HtrA2 in the mitochondria

The processing and metabolism of amyloid precursor protein (APP) is a major interest in Alzheimer disease (AD) research, because not only amyloid beta (Abeta) peptide, but also cellular or mitochondrial APP are intimately involved in cellular dysfunction and AD pathogenesis. Here we demonstrate that APP is directly and efficiently cleaved by the HtrA2 serine protease in vitro and in vivo. Using several APP mutants and N-terminal amino acid sequencing, we identified that the HtrA2-mediated APP cleavage product is the C161 fragment encompassing amino acids 535-695 of APP695. The immunofluorescence and subcellular fractionation studies indicate that APP is partly colocalized with HtrA2 in the mitochondria where HtrA2 can cleave APP under normal conditions. The HtrA2-cleaved C161 fragment was detected in the cytosolic fraction; therefore, we postulate that the C161 fragment is released into the cytosol after cleavage of APP by HtrA2. Interestingly, the level of C161 was remarkably decreased in motor neuron degeneration (mnd2) mice in which the serine protease activity of HtrA2 was greatly reduced. These results show that the protease activity of HtrA2 is essential for the production of C161 and that processing of APP into C161 is a natural event occurring under normal physiological conditions. Our study suggests that the direct cleavage of mitochondrial APP by HtrA2 may prevent mitochondrial dysfunction caused by accumulation of APP and that the regulation of HtrA2 protease activity may be a therapeutic target in AD.

Direct Modulation of Phospholipase D Activity by Gβγ

Phospholipase D-mediated hydrolysis of phosphatidylcholine is stimulated by protein kinase C and the monomeric G proteins Arf, RhoA, Cdc42, and Rac1, resulting in complex regulation of this enzyme. Using purified proteins, we have identified a novel inhibitor of phospholipase D activity, Gbetagamma subunits of heterotrimeric G proteins. G protein-coupled receptor activation alters affinity between Galpha and Gbetagamma subunits, allowing subsequent interaction with distinct effectors. Gbeta1gamma1 inhibited phospholipase D1 and phospholipase D2 activity, and both Gbeta1gamma1 and Gbeta1gamma2 inhibited stimulated phospholipase D1 activity in a dosedependent manner in reconstitution assays. Reconstitution assays suggest this interaction occurs through the amino terminus of phospholipase D, because Gbeta1gamma1 is unable to inhibit an amino-terminally truncated phospholipase D construct, PLD1.d311, which like full-length phospholipase D isoforms, requires phosphatidylinositol-4,5-bisphosphate for activity. Furthermore, a truncated protein consisting of the amino-terminal region of phospholipase D containing the phox/pleckstrin homology domains was found to interact with Gbeta1gamma1, unlike the PLD1.d311 recombinant protein, which lacks this domain. In vivo, expressed recombinant Gbeta1gamma2 was also found to inhibit phospholipase D activity under basal and stimulated conditions in MDA-MB-231 cells, which natively express both phospholipase D1 and phospholipase D2. These data demonstrate that Gbetagamma directly regulates phospholipase D activity in vitro and suggest a novel mechanism to negatively regulate phospholipase D signaling in vivo.

A feasibility study of adenosine triphosphate-based chemotherapy response assay (ATP-CRA) as a chemosensitivity test for lung cancer

PURPOSE

A chemosensitivity test can reflect the differences in responses of individual cancer patients to chemotherapeutic agents. The adenosine triphosphate-based chemotherapy response assay (ATP-CRA) is an accurate method, which does not require a large amount of tissue specimen. So far, no studies have evaluated the utility of the ATP-CRA in Korea. Therefore, we investigated the clinical usefulness of the ATP-CRA in 53 patients with lung cancer.

MATERIALS AND METHODS

Tumor tissues were obtained from bronchoscopic biopsies or surgical resections. The validity of ATP-CRA was assessed focusing on the success rate, experimental error level (intraassay mean coefficient of variation [CV]) and reproducibility.

RESULTS

The overall success rate of ATP-CRA was 90.6% (48/53). Normal cells were effectively eliminated from the tumor tissues with the use of ficoll gradient centrifugation and immunomagnetic separation, which was confirmed using loss of heterozygosity analysis of the 3p deletion. The mean CV of ATP assays was 10.5+/-4.6%. The reproducibility of ATP assays was 94+/-3.8%. The results of the ATP assays were reported to physicians within 7 days of specimen collection. More than 6 anticancer drugs were tested on the tumor specimens obtained from bronchoscopic biopsies.

CONCLUSION

The ATP-CRA is a stable, accurate and potentially practical chemosensitivity test in patients with lung cancer.

Synthesis of 99mTc-ciprofloxacin by different methods and its biodistribution

We describe here the synthesis of 99mTc-ciprofloxacin by four different methods and its biodistribution. All of the methods gave high radiochemical yields of > or = 90% and high stability of > or = 90% at 6 h after preparation. However HPLC analysis, bacterial binding assay, and in vivo distribution for the four 99mTc-ciprofloxacins showed different results. Among these methods, the use of formamidine sulfinic acid with microwave heating (Method A) was fast and easy, and gave more desirable biological properties than the other methods.

Structural comparison of zebrafish Elav/Hu and their differential expressions during neurogenesis

The present communication reports the isolation and characterization of three new zebrafish elav/Hu (Kim, C.-H., Ueshima, E., Muraoka, O., Tanaka, H., Yeo, S.-Y., Huh, T.-L. and Miki, N., Zebrafish elav/HuC homologue as a very early neuronal marker. Neurosci. Lett., 216 (1996) 109-112) homologues, HuA, HuD and HuG. While HuA and HuG showed weak and ubiquitous expressions, HuD, as well as HuC, were specifically expressed in the neuronal cells. The first expression of HuD was detectable of the 10-somite stage, that is, several hours later than HuC. After 24 h of embryonic development, although HuD and HuC expressions overlapped overall, the cells expressing HuD were restricted to subsets of the HuC-positive neuronal cells in the brain and spinal cord. These differentially regulated spatial and temporal expression patterns implied distinct roles for HuC and HuD in neuronal determination and neuronal differentiation, respectively.

A randomized trial of a combined physical activity and environmental intervention in nursing home residents: do sleep and agitation improve?

OBJECTIVES

The purpose of this study was to test whether an intervention combining increased daytime physical activity with improvement in the nighttime environment improves sleep and decreases agitation in nursing home residents.

DESIGN

A randomized trial.

SETTING

One community nursing home in the Los Angeles, California area.

PARTICIPANTS

Twenty-nine incontinent residents (mean age 88.3 years, 90% female).

INTERVENTION

Subjects were randomized to receive either (1) an intervention combining increased daytime physical activity (14 weeks in duration) plus a nighttime program (5 nights in duration) to decrease noise and sleep-disruptive nursing care practices (intervention group), or (2) the nighttime program alone (control group).

MEASUREMENTS

Daytime physical activity monitors and structured physical function assessments; nighttime wrist activity monitors to estimate nighttime sleep; and timed daytime behavioral observations of sleep versus wakefulness, either in or out of bed, and agitation.

RESULTS

Physical function measures did not change significantly (MANOVA for repeated measures, group by time effect). Wrist actigraphy estimation of nighttime percent sleep (time asleep over time monitored in bed at night) increased in intervention subjects from 51.7% at baseline to 62.5% at follow-up compared with 67.0% at baseline to 66.3% at follow-up in controls (MANOVA, group by time, F = 4.42, P = .045, df = 27). At follow-up, intervention subjects averaged a 32% decrease in the percent of daytime observations in bed compared with baseline, with essentially no change in controls (MANOVA, group by time, F = 5.31, P = .029, df = 27). Seven of 15 intervention subjects had a decrease in observed agitation at follow-up, compared with baseline, versus only 1 of 14 controls with a decrease in observed agitation.

CONCLUSIONS

This study provides preliminary evidence that an intervention combining increased physical activity with improvement in the nighttime nursing home environment improves sleep and decreases agitation in nursing home residents.

Pharmacokinetics of DA-125, a new anthracycline, after intravenous administration to spontaneously hypertensive rats and DOCA-salt-induced hypertensive rats

Pharmacokinetic parameters-including tissue distribution, biliary excretion, and urinary excretion of M1-M4-were compared after an intravenous administration of DA-125 (a new anthracycline derivative; 20 mg/kg body weight) to male spontaneously hypersensitive rats (SHRs) at 16 weeks (an animal model for human primary hypertension) and at 6 weeks (corresponding to the early phase of the development of hypertension, at which time blood pressure remains within the normotensive range) of age and their age-matched control Kyoto-Wistar rats, and male deoxycorticosterone acetate-salt-induced Sprague-Dawley rats (DOCA-salt rats, an animal model for human secondary hypertension) at 16 weeks of age and their age-matched control Sprague-Dawley rats. Mean plasma concentrations of both M2 and M4, and the resultant area under the plasma concentration-time curve from time 0 to last measured time [AUCT; M2 (68.9 vs. 29.3 micrograms-min/ml) and M4 (53.4 vs. 33.4 micrograms-min/ml)], increased significantly in SHRs at 16 weeks of age, compared with their control rats. Similar results were also obtained from DOCA-salt rats at 16 weeks of age, compared with their control rats. However, values were not significantly different between SHRs at 6 weeks of age and their control rats. Previous data indicated that the significant increase in plasma concentrations and the resultant AUCT values of both M2 and M4 in SHRs at 16 weeks of age were due to the hypertension state itself, and not to any hereditary characteristics of the SHRs. The significantly increased plasma concentrations and the resultant AUCT values of M2 in both SHRs and DOCA-salt rats at 16 weeks of age were due to the significantly decreased biliary excretion of M2 and possibly to the increased amount of aldo-keto reductase in the liver. However, the increase in the two aforementioned pharmacokinetic parameters in the case of M4 were possibly due solely to the increased amount of aldo-keto reductase in the liver.

Comparison of pharmacokinetics of M1, M2, M3, and M4 after intravenous administration of DA-125 or ME2303 to mice and rats. New adriamycin analogues containing fluorine

The pharmacokinetics of M1, M2, M3 and/or M4 were compared after intravenous (i.v.) administration of DA-125 and/or ME2303 to mice (25 mg kg(-1)) and rats (5, 10, 20, 30, and 40 mg kg(-1)). The mean plasma concentrations of M1 were detected up to 8 h after i.v. administration of both DA-125 and ME2303 to mice, and were significantly higher for DA-125 than ME2303; this resulted in a considerably greater AUC (303 against 148 micrograms min mL(-1)) and a considerably slower CL of M1 (69.3 against 136 mL min-1 kg(-1)) after i.v. administration of DA-125. The MRT (371 against 189 min) and CLNR of M1 (68.7 against 136 mL min-1 kg(-1)) were considerably greater and slower, respectively, after i.v. administration of DA-125. The mean plasma concentrations of M2 were detected up to 8 and 4 h after i.v. administration of DA-125 and ME2303, respectively, to mice and were significantly higher for DA-125 than ME2303, resulting in a considerably greater AUC of M2 (148 against 27.1 micrograms min mL(-1)) after i.v. administration of DA-125. The mean plasma concentrations of M3, being the lowest among M1-M4, were detected only up to 15 min after i.v. administration of both DA-125 and ME2303 to mice, and were comparable after i.v. administration of DA-125 and ME2303 to mice. The mean plasma concentrations of M4 were detected up to 8 h after i.v. administration of both DA-125 and ME2303 to mice, and were higher after i.v. administration of DA-125 than ME2303, resulting in a considerably greater AUC of M4 (197 against 61.9 micrograms min mL(-1)) after i.v. administration of DA-125. Similar results on M1 and M2 were also obtained from rats: the mean plasma concentrations of both M1 and M2 were significantly higher after i.v. administration of DA-125, 10 mg kg(-1), than after ME2303. The plasma concentrations of M1, M2, and M4, and hence their AUCs, were significantly higher after i.v. administration of DA-125, 5, 10, 20, 30, and 40 mg kg(-1), to rats than after ME2303: the mean plasma concentrations of M2, approximately 0.1-0.4 micrograms mL(-1), were maintained from 30 min to 8-10 h after i.v. administration of DA-125, 20, 30, and 40 mg kg(-1), to rats; the plasma concentrations of M3 were the lowest among M1-M4 at all DA-125 doses; and those of M1 and M4 were maintained for a long period of time. However, after i.v. administration of M2, 5 mg kg(-1), to rats, the mean plasma concentrations of M2 were detected up to 60 min with a mean terminal half-life of only 38.8 min, and the concentrations of M3 were negligible. After i.v. administration of M3, 5 mg kg(-1), to rats, the mean plasma concentrations of M3 were detected up to 15 min; the plasma concentrations of M4, reaching their peak at 5 min, decayed more slowly and were higher than those of M3. The AUC of M4 after i.v. administration of M3, 5 mg kg(-1), was comparable to that after i.v. administration of M4, 5 mg kg(-1), to rats, suggesting that M4 is formed fast and almost completely from M3. M1 was not detected in plasma after i.v. administration of either M2 or M3 to rats. After i.v. administration of M4, 5 mg kg(-1), to rats, the mean plasma concentrations of M4 decayed fast with a mean terminal half-life of 43.9 min and neither M2 nor M3 were detected in plasma. The following disposition mechanisms for M1, M2, M3, and M4 after i.v. administration of DA-125 to rats could be obtained from the above data; (i) the maintenance of plasma concentrations of M2 for a longer period of time after i.v. administration of DA-125 than those after i.v. administration of M2 could be due to the continuous formation of M2 from M1; (ii) the lowest plasma concentrations of M3 among M1-M4 after i.v. administration of DA-125 could be due to the fast and almost complete information of M4 from M3 as soon as M3 is formed from M1, and not due to the fast renal excretion of unchanged M3; (iii) M4 was exclusively and continuously formed from M3 and the formation of M4 from M2 was negligible; and (i.v.) reversible me

Pharmacokinetics of DA-125, a new anthracycline, after intravenous administration to uranyl nitrate-induced acute renal failure rats or protein-calorie malnutrition rats

The pharmacokinetics of DA-125 were compared after intravenous (i.v.) administration of the drug, 10 mg kg-1, to control male Sprague-Dawley rats (n = 9) and uranyl nitrate-induced acute renal failure (U-ARF, n = 12) rats, or male Sprague-Dawley rats fed on a 23% (control, n = 8) or a 5% (protein-calorie malnutrition, PCM, n = 9) protein diet. After i.v. administration of DA-125, almost 'constant' plasma concentrations of M1, M2, and M4 were maintained from 1-2 h to 8-10 h in all rat groups due to the continuous formation of M2 from M1 and M4 from M3. The plasma concentrations of M3 were the lowest among M1-M4 for all rat groups due to the rapid and almost complete conversion of M3 to M4 and other metabolite(s). The AUCt values of M1 (115 against 82.5 micrograms min mL-1), M2 (33.0 against 23.6 micrograms min mL-1), and M4 (26.3 against 15.1 micrograms min mL-1) were significantly higher in the U-ARF rats than in the control rats. The percentages of i.v. dose excreted in 24 h urine as M1 (under the detection limit against 0.316%), M2 (under the detection limit against 5.58%), and M4 (0.0174 against 0.719%)--expressed in terms of DA-125--were significantly lower in the U-ARF rats than in the control rats, and this could be due to the decreased kidney function in the U-ARF rats. However, the percentages of i.v. dose recovered from the GI tract at 24 h as M1 (0.0532% against under the detection limit), M3 (0.0286% against under the detection limit), and M4 (0.702% against 0.305%)--expressed in terms of DA-125--were significantly greater in the U-ARF rats than in the control rats. All U-ARF rats had ascites, but the concentrations of M1 (0.0320 micrograms mL-1), M2 (0.0265 micrograms mL-1), M3 (under the detection limit), and M4 (0.032 micrograms mL-1) in the ascites from one rat were almost negligible. The plasma concentrations and most of the pharmacokinetic parameters of M1, M2, and M4 were not significantly different between the PCM rats and their control rats.

Correlation of CGS 19755 neuroprotection against in vitro excitotoxicity and focal cerebral ischemia

The in vivo neuroprotective effect and brain levels of cis-4-phosphonomethyl-2-piperidine carboxylic acid (CGS 19755), a competitive N-methyl-D-aspartate (NMDA) antagonist, were compared with its in vitro neuroprotective effects. The dose-response for in vitro neuroprotection against both NMDA toxicity and combined oxygen-glucose deprivation (OGD) was determined in murine neocortical cultures. Primary cultures of neocortical cells from feta mice were injured by exposure to 500 microM NMDA for 10 min or to OGD for 45 min. The effect of CGS 19755 in both injury paradigms was assessed morphologically and quantitated by determination of lactate dehydrogenase release. Near complete neuroprotection was found at high doses of CGS 19755. The ED50 for protection against NMDA toxicity was 25.4 micro M, and against OGD the ED50 was 15.2 microM. For the in vivo paradigm rabbits underwent 2 h of left internal carotid, anterior cerebral, and middle cerebral artery occlusion followed by 4 h reperfusion; ischemic injury was assessed by magnetic resonance imaging and histopathology. The rabbits were treated with 40 mg/kg i.v. CGS 19755 or saline 10 min after arterial occlusion. CSF and brain levels of CGS 19755 were 12 microM and 5 microM, respectively, at 1 h, 6 microM and 5 microM at 2 h, and 13 microM and 7 microM at 4 h. These levels were neuroprotective in this model, reducing cortical ischemic edema by 48% and ischemic neuronal damage by 76%. These results suggest that a single i.v. dose penetrates the blood-brain barrier, attaining sustained neuroprotective levels that are in the range for in vitro neuroprotection.

Neuroprotection by N-methyl-D-aspartate antagonists in focal cerebral ischemia is dependent on continued maintenance dosing

While N-methyl-D-aspartate antagonists have been shown to attenuate neuronal damage in focal cerebral ischemia, few studies have examined whether continuous or multiple dose treatment is necessary for maximum efficacy. We studied the effect of a loading dose only or load plus maintenance infusion using several non-competitive N-methyl-D-aspartate antagonists (dextromethorphan, dextrorphan, MK-801) and the levorotatory enantiomer of dextromethorphan (levomethorphan) in a rabbit model of focal cerebral ischemia. Forty-seven anesthetized rabbits underwent occlusion of the left internal carotid, anterior cerebral and middle cerebral arteries for 2 h followed by 4 h of reperfusion. Drugs were administered 10 min after occlusion. Dextromethorphan and dextrorphan protected against ischemic edema only when given as load plus maintenance (29% and 31% reduction, respectively), while both load only and load plus maintenance of MK-801 protected against edema (26% and 31% reduction, respectively). Levomethorphan load plus maintenance also protected against ischemic edema (25% reduction). However, dextromethorphan and dextrorphan both required maintenance infusion to protect against ischemic neuronal damage (24% and 27% reduction in area of ischemic neuronal damage, respectively), while levomethorphan failed to protect against neuronal injury even when given as load plus maintenance. Administration of MK-801 as load plus maintenance reduced ischemic neuronal damage by 23%, but this difference was not quite statistically significant. These results suggest that processes of ischemic damage, such as excitotoxic injury, continue for several hours beyond the initial period of focal ischemia, and that non-competitive N-methyl-D-aspartate antagonists require more prolonged administration to achieve neuroprotection.(ABSTRACT TRUNCATED AT 250 WORDS)

The pharmacokinetics of methotrexate after intravenous administration of methotrexate-loaded proliposomes to rats

The pharmacokinetics and tissue distribution of methotrexate (MTX) were investigated after intravenous (i.v.) injection of free MTX (treatment I), MTX-loaded proliposomes (treatment II), and empty proliposomes mixed manually with free MTX (treatment III), 8 mg kg-1, to rats using an HPLC assay. After i.v. infusion in 1 min, the plasma concentration of MTX (Cp), the area under the plasma concentration-time curve (AUC, 639 versus 913 micrograms min mL-1), the terminal half-life (t1/2, 48.8 versus 397 min), the mean residence time (MRT, 8.40 versus 325 min), and the apparent volume of distribution at steady state (Vss, 98.1 versus 2800 mL kg-1) were significantly higher; however, the total body clearance (CL, 12.5 versus 8.76 mL min-1 kg-1), renal clearance (CLR, 4.49 versus 2.78 mL min-1 kg-1), non-renal clearance (CLNR, 7.50 versus 5.99 mL min-1 kg-1), and the amount of MTX excreted in urine (Xu, 808 versus 685 micrograms, p < 0.0948) were significantly lower from treatment II than from treatment I. This could be due to the fact that some of the MTX-loaded liposomes (formed immediately after hydration of MTX-loaded proliposomes) are entrapped in tissues and the rest are present in the plasma (higher MRT and Vss from treatment II), and MTX is slowly released from MTX-loaded liposomes (higher t1/2 from treatment II). In the present HPLC assay, the concentrations of MTX represent the sum of free MTX and MTX loaded in liposomes (higher Cp and AUC, slower CL from treatment II). After i.v. infusion in 1 min, some pharmacokinetic parameters, such as t1/2, MRT, and Vss, were significantly different between treatments I and III; however, the differences seemed to be smaller than those between treatments I and II. After 30 min from i.v. infusion, the tissue to plasma (T/P) ratios of MTX in kidney and stomach from treatment II were significantly lower than those from treatment I. This suggested that the i.v. administration of MTX-loaded proliposomes might have fewer side effects in the organs than that of free MTX. The mean amount of MTX loaded in MTX-loaded proliposomes was 2.54 mg/g proliposomes and the MTX was released slowly from hydrated MTX-loaded proliposomes when incubated with phosphate-buffered saline (PBS), rat plasma, or rat liver homogenate.

Simultaneous determination of a new anthracycline, DA-125, and its metabolites M1, M2, M3 and M4 in plasma and urine by high-performance liquid chromatography

A high-performance liquid chromatographic method was developed for the simultaneous determination of a new anthracycline, DA-125 (I), and its metabolites (M1, M2, M3, and M4) in rat plasma and urine using fluorescein as an internal standard. Compound I, a prodrug of M1, is a beta-alanine derivative of M1, and only M1 shows antineoplastic activity. The method involved extraction or deproteinization followed by injection of 80-100 microliters of the aqueous layer or supernatant onto a C18 reversed-phase column. The mobile phases were 1% acetic acid-isopropyl alcohol-methanol (70:20:10, v/v) or 5 mM of ion-pairing chromatography reagent (IPC B8)-isopropyl alcohol-methanol (70:20:10, v/v) for the extraction or deproteinization methods, respectively. The flow-rate was 1.5 ml/min for both methods. The column effluent was monitored by a fluorescence detector with excitation wavelength of 488 nm and emission wavelength of 556 nm. The detection limits for M1, M2, M3, and M4 in rat plasma and urine were 50 ng/ml for all compounds using the extraction method, and 100, 50, 50, 50, and 50 ng/ml for I, M1, M2, M3 and M4 in rat plasma respectively, using the deproteinization method. No interferences from endogenous substances, adriamycin or daunorubicin were found.