White and gray matter alterations in de novo PD patients: which matter most?

OBJECTIVES

This paper aimed to identify white matter (WM) and gray matter (GM) abnormalities in a sample of early PD patients, and their correlations with motor and non-motor symptom severity.

METHODS

We enrolled 62 de novo PD patients and 31 healthy subjects. Disease severity and non-motor symptom burden were assessed by the Unified Parkinson's Disease Rating Scale part III and the Non-Motor Symptoms Scale, respectively. Cognitive performance was assessed using Montreal Cognitive Assessment and Frontal Assessment Battery. All subjects underwent a 3-Tesla MRI protocol. MRI analyses included tract-based spatial statistics, cortical thickness, and subcortical and cerebellar volumetry.

RESULTS

In comparison to control subjects, PD patients exhibited lower fractional anisotropy and higher mean, axial, and radial diffusivity in most WM bundles, including corticospinal tracts, the internal and external capsule, the anterior and posterior thalamic radiations, the genu and body of the corpus callosum, cerebellar peduncles, and superior and inferior longitudinal and fronto-occipital fasciculi. Correlations between Montreal Cognitive Assessment scores and fractional anisotropy values in the right posterior thalamic radiation, left superior corona radiata, right inferior-fronto-occipital fasciculus, left inferior longitudinal fasciculus, bilateral anterior thalamic radiations, and bilateral superior longitudinal fasciculi were found. Smaller cerebellar volumes in early PD patients in the left and right crus I were also found. No GM changes were present in subcortical or cortical regions.

CONCLUSION

The combined evaluation of WM and GM in the same patient sample demonstrates that WM microstructural abnormalities precede GM structural changes in early PD patients.

Focal Dystonia: Functional Connectivity Changes in Cerebellar-Basal Ganglia-Cortical Circuit and Preserved Global Functional Architecture

BACKGROUND AND OBJECTIVES

Neuroimaging studies suggest that changes in the cerebellar-basal ganglia-thalamo-cortical sensorimotor circuit are a pathophysiologic feature of focal dystonia. However, it remains unclear whether structural and functional alterations vary in different forms of focal dystonia. Thus, in patients with cervical dystonia (CD) and blepharospasm (BSP), we aimed to investigate structural damage and resting-state functional alterations using whole-brain and seed-based approaches to test the hypothesis of possible functional connectivity (FC) alterations in specific circuits, including the cerebellum, basal ganglia, and cerebral cortex, in the context of preserved global FC.

METHODS

In this cross-sectional study, we applied a multimodal 3T MRI protocol, including 3-dimensional T1-weighted images to extract brain volumes and cortical thickness, and fMRI at rest to study FC of the dentate nucleus and globus pallidus with a seed-based approach and whole-brain FC with a graph theory approach.

RESULTS

This study included 33 patients (17 with CD [14 female] age 55.7 ± 10.1 years, 16 with BSP [11 female] age 62.9 ± 8.8 years) and 16 age- and sex-matched healthy controls (HC) (7 female) 54.3 ± 14.3 years if age. Patients with CD, patients with BSP, and HC did not differ in terms of cortical or subcortical volume. Compared to HC, both patients with CD and patients with BSP had a loss of dentate FC anticorrelation with the sensorimotor cortex. Patients with CD and those with BSP showed increased pallidal FC with the cerebellum, supplementary motor area, and prefrontal cortices with respect to HC. Increased dentate FC with the cerebellum and thalamus and increased pallidal FC with the bilateral thalamus, sensorimotor and temporo-occipital cortices, and right putamen were present in patients with CD but not patients with BSP compared to HC. Measures of global FC, that is, global efficiency and small-worldness, did not differ between patients and HC.

DISCUSSION

Both patients with CD and those with BSP showed altered dentate and pallidal FC with regions belonging to the integrated cerebellar-basal ganglia-thalamo-cortical sensorimotor circuit, supporting the concept that focal dystonia is a disorder of specific networks and not merely a result of basal ganglia alterations in the context of a preserved whole-brain functional architecture. Differences in functional interplay among specific brain structures may distinguish CD and BSP.

Resting-state functional connectivity of anterior and posterior cerebellar lobes is altered in multiple sclerosis

BACKGROUND

Damage to the cerebellar sensorimotor and cognitive domains may underlie physical and cognitive disability.

OBJECTIVE

To investigate resting-state functional connectivity (FC) of sensorimotor and cognitive cerebellum, and clinical correlates in multiple sclerosis (MS).

METHODS

A total of 119 patients with MS and 42 healthy subjects underwent multimodal 3T-magnetic resonance imaging (MRI). Patients were evaluated using the Expanded Disability Status Scale and Multiple Sclerosis Functional Composite Scale. After parcellation of sensorimotor (lobules I-V + VIII) and cognitive cerebellum (lobules VI, VII, IX, X), we calculated cerebellar resting-state FC using a seed-based approach.

RESULTS

In patients with MS, the sensorimotor cerebellum showed increased FC mainly with cerebellar, thalamic, and cortical (frontal, parietal, temporal) areas and decreased FC with insular areas; the cognitive cerebellum showed increased FC mainly with thalamic and cortical (temporal-occipital) areas, and decreased FC with frontal-insular areas. Both sensorimotor and cognitive cerebellar FC negatively correlated with disability, and positively with cognitive scores. Cerebellar structural damage only partially influenced results.

CONCLUSION

The two neocerebellar circuits showed altered FC with subcortical and cortical areas. The association between increased sensorimotor and cognitive cerebellar FC and low levels of physical and cognitive disability suggests that altered FC might modulate the effects of cerebellar structural damage on clinical condition.

Practice-dependent motor cortex plasticity is reduced in non-disabled multiple sclerosis patients

OBJECTIVES

Skill acquisition after motor training involves synaptic long-term potentiation (LTP) in primary motor cortex (M1). In multiple sclerosis (MS), LTP failure ensuing from neuroinflammation could contribute to worsen clinical recovery. We therefore addressed whether practice-dependent plasticity is altered in MS.

METHODS

Eighteen relapsing-remitting (RR)-MS patients and eighteen healthy controls performed 600 fast abductions of index finger in 30 blocks of 20 movements. Before and after practice, transcranial magnetic stimulation (TMS) was delivered over the hot spot of the trained first dorsal interosseous muscle. Movements kinematics, measures of cortical excitability, and the input/output curves of motor evoked potentials (MEPs) were assessed.

RESULTS

Kinematic variables of movement improved with practice in patients and controls to a similar extent, although patients showed lower MEPs amplitude increase after practice. Practice did not change the difference in resting motor threshold values observed between patients and controls, nor did modulate short-interval intracortical inhibition. Clinical/radiological characteristics were not associated to practice-dependent effects.

CONCLUSIONS

Practice-induced reorganization of M1 is altered in non-disabled RR-MS patients, as shown by impaired MEPs modulation after motor learning.

SIGNIFICANCE

These findings suggest that in RR-MS physiological mechanisms of practice-dependent plasticity are altered.

White matter rather than gray matter damage characterizes essential tremor

OBJECTIVES

We investigated changes in gray matter (GM) and white matter (WM) in the whole brain, including both cortical and subcortical structures, and their relationship with tremor severity, psychiatric symptoms, and cognitive impairment in patients affected by essential tremor (ET).

METHODS

We studied 19 ET patients and 15 healthy subjects (HS). All the subjects underwent a 3-T MRI study based on 3D-T1 and diffusion tensor images. For the GM analysis, cortical thickness was assessed by using the Computational Anatomy Tool, basal ganglia and thalamus volumes by using the FMRIB software library, and cerebellum lobular volumes by using the spatial unbiased atlas template. For the WM assessment, we performed a voxel-wise analysis by means of tract-based spatial statistics. Patients' tremor severity and psychiatric and cognitive disorders were evaluated by means of standard clinical scales. Neuroimaging data were correlated with clinical scores.

RESULTS

We found significantly smaller right and left thalamic volumes in ET patients than in HS, which correlated with cognitive scores. We did not observe any significant differences either in cortical thickness or in cerebellar lobular volumes between patients and HS. WM abnormalities were detected in most hemisphere bundles, particularly in the corticospinal tract, cerebellar peduncles, and corpus callosum. The WM abnormalities significantly correlated with tremor severity, cognitive profile, and depression.

CONCLUSION

Our study indicates that ET is characterized by several GM and WM changes of both infra- and supratentorial brain structures. The results may help to better understand mechanisms underlying tremor severity and psychiatric and cognitive impairment in ET.

KEY POINTS

• We performed a comprehensive evaluation of gray and white matter in the same sample of patients with essential tremor using recently developed data analysis methods. • Essential tremor is characterized by widespread gray and white matter changes in both infra- and supratentorial brain structures. The results may help to better understand motor and non-motor symptoms in patients with essential tremor.

Triterpenoids and ellagic acid derivatives from in vitro cultures of Camptotheca acuminata Decaisne

The metabolic profile of secondary products in calli and cell suspension cultures of Camptotheca acuminata Decaisne was investigated and compared to that of the leaves and roots taken from the plant. Neither in vitro system produced the anticancer quinoline alkaloid camptothecin (CPT); they accumulated discrete quantities of polyhydroxylated triterpenoids, different from those found in the plant organs, and ellagic acid derivatives. Nine ellagic acid derivatives (1a-1d and 2a-2e) and eight triterpenoid acids (3a-3e and 4a-4c) were isolated and characterised. All the identified triterpenes were related to ursane- or oleanane-type skeletons and their concentrations rose to 4.5% in suspended cells.

Accumulation of essential oils in relation to root differentiation in Angelica archangelica L

The accumulation of essential oils in Angelica archangelica subsp. archangelica roots at different developmental stages was investigated through histochemical and chemical analyses. Roots less than 1 mm in diameter showed a primary diarch structure and two primary secretory ducts in the pericycle. These ducts were ephemeral and probably became dysfunctional early on. Oil accumulation was observed only in the secondary secretory ducts formed by cambium activity and located in the secondary phloem. Gas chromatographic analyses revealed that only taproots exceeding 5 mm in diameter contained a high concentration of alpha- and beta-phellandrene, which appreciably influence the oil's aroma.

Comparison between metabolite productions in cell culture and in whole plant of Maclura pomifera

Plant tissue cultures of Maclura pomifera showed a metabolite accumulation pattern which was both quantitatively and qualitatively different from that of the parent plant. Triterpenes and flavonoids were isolated from callus and cell cultures, however, xanthones and stilbenes, which have been reported in the whole plant, were not found. Among the flavonoids, flavones and flavanones were produced preferentially by the suspended cells, but with the prenyl substituents exclusively on ring A, while the isoflavones did not show the 3',4'-dihydroxyl substitution pattern found in the products isolated from fruits. A new prenylated 6'-deoxychalcone was also isolated from the callus and cell cultures.

Histological study of callus formation and optimization of cell growth in Taxus baccata

Callus growth of Taxus baccata was optimized when Murashige and Skoog or B5 media were used with 2,4-D/kinetin ratios of 1:0.1, 2:0.1, and 5:0.1, when statistically equivalent results were obtained. A cell suspension culture was successfully achieved with a 3-fold increase in fresh weight after 40 days. Histological examination showed that in the leaf explants both the epidermis and mesophyll tissues divided to produce callus. In the stem explants callus formation was due to the cell division of the cortical parenchyma and of the cambium.

Metabolites from in vitro cultures of Cassia didymobotrya

From suspension cultures of Cassia didymobotrya 7-acetylchrysophanol, chrysophanol-physcion-l0,l0'-bianthrone, (E)- and (Z)-3'-hydroxy-3,4,5'-trimethoxystilbene, (E)-4,3'-dihydroxy-3,5'-dimethoxystilbene and 7,4'-dihydroxy-3,5,3'-trimethoxyflavone have been isolated along with several known metabolites.