Functional MRI in the assessment of cortical activation in subjects with Parkinson’s disease

PURPOSE: The purpose of this study was to evaluate cortical activation patterns in patients with Parkinson's disease during a relatively complex motor task. MATERIALS AND METHODS: Seven patients (six men and one woman) with lateralised akinetic-rigid Parkinson's disease underwent functional magnetic resonance imaging (MRI) of the brain with a 1.5-T magnet. Finger tapping was chosen as a motor task. The control group included 11 volunteers (six men and five women) with no neurological disease. RESULTS: Patients showed hyperactivity of the ipsilateral and contralateral motor cortex associated with bilateral over-activation of the parietal cortex during movement of the affected hand. In some cases, there was a lack of activation of the pre-motor and supplementary motor areas whereas, when present, activation in these areas was greater during movement of the healthy hand. Finally, activation of the occipital cortex was found in all patients as a result of their tendency to control movement visually. CONCLUSIONS: Results of this study confirm a re-organisation of cortical circuits due to subcortical damage in patient's with Parkinson's disease.     

Age-specific activation of cerebral areas in motor imagery—a fMRI study

Introduction

The objectives of this study were to study the age-specific activation patterns of cerebral areas during motor execution (ME) and motor imaging (MI) of the upper extremities and to discuss the age-related neural mechanisms associated with ME or MI.

Methods

The functional magnetic resonance imaging technique was used to monitor the pattern and intensity of brain activation during the ME and MI of the upper extremities in 20 elderly (>50 years) and 19 young healthy subjects (<25 years).

Results

No major differences were identified regarding the activated brain areas during ME or MI between the two groups; however, a minor difference was noted. The intensity of the activated brain area during ME was stronger in the older group than in the younger group, while the results with MI were the opposite. The posterior central gyrus and supplementary motor area during MI were more active in the younger group than in the older group. The putamen, lingual, and so on demonstrated stronger activation during dominant hand MI in the older group.

Conclusion

The results of this study revealed that the brain structure was altered and that neuronal activity was attenuated with age, and the cerebral cortex and subcortical tissues were found to be over-activated to achieve the same level of ME and MI, indicating that the activating effects of the left hemisphere enhanced with age, whereas the inhibitory effects declined during ME, and activation of the right hemisphere became more difficult during MI.     

Structure-activity relationship for toxicity of α-pyrrolidinophenones in human aortic endothelial cells

In this study, we found that exposure of 20 μM α-pyrrolidinooctanophenone (α-POP), a new synthetic cathinone, time- and dose-dependently reduced viability of human aortic endothelial (HAE) cells, and the 50% lethal concentration (LC₅₀) for α-POP in its 48-h treatment was 15.6 μM. In addition, the LC₅₀ comparison of α-POP and α-pyrrolidinoheptanophenone (α-PHPP) toxicity against ten human cells exhibited that vascular (HAE and human aortic smooth muscle) and bronchial epithelial BEAS-2B cells were more susceptible to the cytotoxicity than neuronal (SK-N-SH and A172), gastrointestinal (DLD1 and MKN45), hepatic HepG2, renal HEK293 and pulmonary A549 cells. The results suggest that abuse of the lipophilic α-pyrrolidinophenones (PPs), such as α-POP and α-PHPP, is more likely to cause damage to the vascular, respiratory and central nervous systems. Structure-activity relationship study of 18 PPs with different alkyl chain lengths and substituents revealed that the endothelial cell toxicity depends on the alkyl chain length (α-POP > α-PHPP > PPs with shorter chains), and the presence of 4′-fluoro or 3′,4′-methylenedioxy group on α-POP and α-PHPP increased the cytotoxicity. In order to understand the cytotoxic mechanism of α-POP and F-α-POP that showed the most potent toxicity, the contribution of reactive oxygen species (ROS) production, caspase-3 activation and DNA fragmentation were investigated. The treatment of HAE cells with α-POP or F-α-POP resulted in remarkable ROS production, and the ROS production and apoptotic events were significantly prevented by pretreating the cells with an antioxidant N-acetyl-l-cysteine, suggesting that ROS-dependent signaling is primarily responsible for endothelial cell apoptosis elicited by the lipophilic synthetic cathinones.     

Mobilisation of mesenchymal cells in cardiac patients: is intense exercise necessary?

Circulating mesenchymal cells (cMCs) have a potential for regenerating damaged tissue, e.g., ischaemic myocardium. In patients (age range: 53-76 years) with stable coronary artery disease cMCs were determined before and after dynamic exercise of moderate (< respiratory compensation threshold (RCT)) (n = 9 patients) or high intensity (>RCT) (n = 11). Only high-intensity exercise (i.e., provoking signs of myocardial ischaemia in 3 patients and ventricular extrasystoles in another) induced a significant increase in cMCs (p = 0.009). These results support the hypothesis that intense exercise (near or at the point of myocardial ischaemia) is a potent stimulus for MC mobilisation.     

Role of DNA methylation in long-term low-dose γ-rays induced adaptive response in human B lymphoblast cells

Abstract

Purpose: With widespread use of ionizing radiation, more attention has been attracted to low-dose radiation (LDR); however, the mechanisms of long-term LDR-induced bio-effects are unclear. Here, we applied human B lymphoblast cell line HMy2.CIR to monitor the effects of long-term LDR and the potential involvement of DNA methylation.

Materials and methods: HMy2.CIR cells were irradiated with 0.032 Gy γ-rays three times per week for 1–4 weeks. Some of these primed cells were further challenged with 2 Gy γ-rays. Cell proliferation, micronuclei formation, gene expression of DNA methyltransferases (DNMT), levels of global genomic DNA methylation and protein expression of methyl CpG binding protein 2 (MeCP2) and heterochromatin protein-1 (HP1) were measured.

Results: Long-term LDR enhanced cell proliferation and clonogenicity and triggered a cellular adaptive response (AR). Furthermore, global genomic DNA methylation was increased in HMy2.CIR cells after long-term LDR, accompanied with an increase of gene expression of DNMT1 and protein expression of MeCP2 and HP1. After treatment with 5-aza-2′-deoxycytidine (5-aza-dC), a DNA methyltransferase inhibitor, the long-term LDR-induced global genomic DNA hypermethylation was decreased and the AR was eliminated.

Conclusion: Global genomic DNA hypermethylation accompanied with increases of DNMT1 and MeCP2 expression and heterochromatin formation might be involved in long-term LDR-induced adaptive response.     

Extrastriatal spreading of microglial activation in Parkinson’s disease: a positron emission tomography study

Background

The neuroinflammatory glial response contributes to the degenerative process in Parkinson’s disease (PD). However, the pattern of microglial progression remains unclear.

Methods

We evaluated microglial activation in early stage PD patients by quantifying changes in neuroinflammation using PET with [¹¹C]DPA713, a selective PET tracer for microglial activation. Eleven PD patients (Hoehn and Yahr stages 1–2) without dementia underwent the [¹¹C]DPA713 PET scan two times with 1 year apart. The binding potential (BP_ND) was estimated with the simplified reference tissue model. Voxelwise and regions of interest analyses were used to compare the regional BP_ND among groups.

Results

Significant increase in [¹¹C]DPA713 BP_ND was found extrastriatally in the occipital, temporal and parietal cortex in PD patients, and the degree of BP_ND became much higher over the brain regions predominantly in the temporal and occipital cortex 1 year later.

Conclusion

The current results indicated that an extrastriatal spreading of microglial activation reflects one of PD pathophysiology occurring at an early stage.

     

The role of higher-order chromatin structure in the yield and distribution of DNA double-strand breaks in cells irradiated with X-rays or α-particles

Purpose : To determine whether the non-random distributions of DNA double-strand breaks in cells observed after alpha-particle irradiation are related to the higher-order structure of the chromatin within the nucleus. Materials and methods : Chinese hamster V79 cells were irradiated as either cellular monolayers, nuclear monolayers with condensed chromatin or nuclear monolayers with relaxed chromatin, and the yields and distribution of DSB measured using two pulsedfield gel electrophoresis protocols capable of separating fragments of 10kbp to 5.7Mbp. Results : Using conventional FAR analysis, the effect of isolating nuclear monolayers and changing the chromatin condensation state was less for α -particle irradiated substrates than for Xirradiated ones. When the total number of breaks was measured by separating and quantifying all the fragments produced in the 10kbp to 5.7 Mbp region, the difference between the observed yields of breaks in X-irradiated cells (7.3 10 9 DSB/Gy/bp) relative to α -particles (12.1 10 -9 DSB/Gy/bp) was largely removed when nuclear monolayers with decondensed chromatin were exposed. The yields, although similar, increased to 44.4 10 -9 DSB/Gy/bp for X-irradiated decondensed nuclear monolayers and 46.6 10 9 DSB/Gy/bp for α -particle irradiated monolayers. However, the α -particle DSB distributions remained non-random. Conclusions : Our results suggest that the non-random distribution of breaks observed in cells with α -particle irradiation, which leads to a high probability for the production of regionally multiply damaged sites, is not related to the underlying chromatin condensation state present in the nucleus.     

Assessment of DNA damage produced by 125I‐triplex‐forming oligonucleotides in cells

Purpose: Triplex‐forming oligodeoxyribonucleotides (TFOs) bind specifically to their target sequences by forming hydrogen bonds within the major groove of the target duplex. When labeled with Auger‐electron‐emitting radioisotopes, TFOs are able to damage the target gene in a process named antigene radiotherapy. We compared radiotoxicity and the amount of DNA damage produced within cultured cells by two ¹²⁵I‐labeled TFOs, one with a single target in the genome and another with multiple targets.

Materials and methods: Radiotoxicity was measured by clonogenic assay while DNA damage was assessed by the number of histone γ‐H2AX foci formed at the sites of DNA double strand breaks (DSBs).

Results: The TFO with multiple nuclear targets was 1.7 fold more radiotoxic and produced on average 1.9 fold more γ‐H2AX foci per cell than the TFO with a single target.

Conclusion: Since the two methods gave comparable results, measuring the number of γ‐H2AX foci per decay may be a useful procedure for the assessment of cytotoxic effects and the intranuclear localization of radionuclides when they produce DSBs.     

Cellular origin of ionizing radiation‐induced NF‐κB activation in vivo and role of NF‐κB in ionizing radiation‐induced lymphocyte apoptosis

Purpose: To investigate the cellular origin of ionizing radiation (IR)‐induced NF‐κB activation in vivo and the role of NF‐κB in IR‐induced lymphocyte apoptosis.

Materials and methods: NF‐κB activities were analysed by gel shift/supershift assay in isolated murine T‐ and B‐cells, macrophages (M?) and tissues from normal and T‐ and B‐cell‐deficient Rag1 mice with or without exposure to IR. IR‐induced lymphocyte apoptosis was determined by analysis of 3,3′‐dihexyloxacarbocyanine iodide (DiOC₆) uptake, annexin‐V staining and the sub‐G0/1 population, or by TUNEL assay.

Results: The results showed that IR activated NF‐κB in lymphocytes, including both T‐ and B‐cells, but failed to do so in M?. Furthermore, T‐ and B‐cell‐deficient Rag1 mice exposed to IR exhibited a significant reduction in NF‐κB activation as compared with normal mice. Although NF‐κB1 (p50) gene knockout or NF‐κB decoy oligonucleotide treatment specifically inhibited IR‐induced lymphocyte NF‐κB activation, they had no significant effect on IR‐induced lymphocyte apoptosis.

Conclusions: This finding suggests that lymphocytes are the main cellular origin of IR‐induced NF‐κB activation in vivo. However, NF‐κB activation has no significant effect on IR‐induced lymphocyte apoptosis.     

Cytogenetic analysis in Chinese hamster cells chronically exposed to low doses of X‐rays

Purpose: It is important to develop simple experimental models to assess the induction of DNA damage and study the different factors involved under controlled conditions. This paper describes the cytogenetic analysis carried out in Chinese hamster cells (CHO) sequentially exposed to very low doses of X‐rays.

Materials and methods: CHO cells were cultured for 14 passages. Irradiation treatment was performed once per passage, and three irradiation doses were employed: 2.5, 5.0 and 10.0?mSv.

Results: Sequential irradiation of CHO cells did not increase the yield of chomatid‐ or chromosome‐type aberrations. However, a significant increase of achromatic lesions (gaps) was found after the first or second X‐ray dose, with all three irradiation doses employed.

Conclusions: The variation in the frequency of gaps as well as that in the mitotic index during the 14 cycles of radiation could be an indication of the induction of genomic instability. According to this, continuous rises and falls in the frequency of gaps as well as in the mitotic index reflects the simultaneous induction of endogenous DNA damage, cell death and cell survival.     

Evaluation of CLINDE as potent translocator protein (18 kDa) SPECT radiotracer reflecting the degree of neuroinflammation in a rat model of microglial activation

Background  The translocator protein (TSPO; 18 kDa), the new name of the peripheral-type benzodiazepine receptor, is localised in mitochondria of glial cells and expressed in very low concentrations in normal brain. Their expression rises after microglial activation following brain injury. Accordingly, TSPO are potential targets to evaluate neuroinflammatory changes in a variety of CNS disorders. Purpose  To date, only a few effective tools are available to explore TSPO by SPECT. We characterised here 6-chloro-2-(4′iodophenyl)-3-(N,N-diethyl)-imidazo[1,2-a]pyridine-3-acetamide or CLINDE in a rat model with different stages of excitotoxic lesion. Methods  Excitotoxicity was induced in male Wistar rats by unilateral intrastriatal injection of different amounts of quinolinic acid (75, 150 or 300 nmol). Six days later, two groups of rats (n = 5–6/group) were i.v. injected with [¹²⁵I]-CLINDE (0.4 MBq); one group being pre-injected with PK11195 (5 mg/kg). Brains were removed 30 min after tracer injection and the radioactivity of cerebral areas measured. Complementary ex vivo autoradiography, in vitro autoradiography ([³H]-PK11195) and immunohistochemical studies (OX-42) were performed on brain sections. Results  In the control group, [¹²⁵I]-CLINDE binding was significantly higher (p < 0.001) in lesioned than that in intact side. This binding disappeared in rats pre-treated with PK11195 (p < 0.001), showing specific binding of CLINDE to TSPO. Ex vivo and in vitro autoradiographic studies and immunohistochemistry were consistent with this, revealing a spatial correspondence between radioactivity signal and activated microglia. Regression analysis yielded a positive relation between the ligand binding and the degree of neuroinflammation. Conclusion  These results demonstrate that CLINDE is suitable for TSPO in vivo SPECT imaging to explore their involvement in neurodegenerative disorders associated with microglial activation. An erratum to this article can be found at     

Chronic low-dose radiation inhibits the cells death by cytotoxic high-dose radiation increasing the level of AKT and acinus proteins via NF-κB activation

Abstract

Purpose: This study explored the effects of low-dose and low-dose-rate irradiation in human lung fibroblast CCD-18Lu cells and examined the role of AKT (protein kinase B, PKB) in cellular responses.

Materials and methods: We examined cell survival after chronic low-dose irradiation (0.01 Gy or 0.05 Gy) with challenging high-dose (2 or 10 Gy) irradiation. We examined the effect of AKT activation on cell survival after chronic low-dose radiation using transduced cells with retroviral vector expressing constitutively active AKT (CA-AKT).

Results: Chronic low-dose priming irradiation increased cells viability against the challenging high-dose irradiation. Irradiation at 0.05 Gy increased cellular levels of AKT and acinus long form (L) and short form (S). The chronic low-dose radiation promoted cells proliferation in the exogenously expressed CA-AKT cells. It also increased nuclear factor-kappa B (NF-κB) activity in a biphasic induction pattern. Suppression of NF-κB activation by mutant form of inhibitor of kappa B alpha (IκBαM) antagonized the radiation-induced expression of AKT and acinus L and S.

Conclusions: Chronic low-dose radiation increases the levels of AKT and acinus proteins via NF-κB activation, and the NF-κB/AKT pathway responding to chronic low-dose irradiation plays an important role in the radiation adaptive response.     

In vivo changes in microglial activation and amyloid deposits in brain regions with hypometabolism in Alzheimer��s disease

Purpose

Amyloid ?? protein (A??) is known as a pathological substance in Alzheimer??s disease (AD) and is assumed to coexist with a degree of activated microglia in the brain. However, it remains unclear whether these two events occur in parallel with characteristic hypometabolism in AD in vivo. The purpose of the present study was to clarify the in vivo relationship between A?? accumulation and neuroinflammation in those specific brain regions in early AD.

Methods

Eleven nootropic drug-na?ve AD patients underwent a series of positron emission tomography (PET) measurements with [¹¹C](R)PK11195, [¹¹C]PIB and [¹⁸F]FDG and a battery of cognitive tests within the same day. The binding potentials (BPs) of [¹¹C](R)PK11195 were directly compared with those of [¹¹C]PIB in the brain regions with reduced glucose metabolism.

Results

BPs of [¹¹C](R)PK11195 and [¹¹C]PIB were significantly higher in the parietotemporal regions of AD patients than in ten healthy controls. In AD patients, there was a negative correlation between dementia score and [¹¹C](R)PK11195 BPs, but not [¹¹C]PIB, in the limbic, precuneus and prefrontal regions. Direct comparisons showed a significant negative correlation between [¹¹C](R)PK11195 and [¹¹C]PIB BPs in the posterior cingulate cortex (PCC) (p?<?0.05, corrected) that manifested the most severe reduction in [¹⁸F]FDG uptake.

Conclusion

A lack of coupling between microglial activation and amyloid deposits may indicate that A?? accumulation shown by [¹¹C]PIB is not always the primary cause of microglial activation, but rather the negative correlation present in the PCC suggests that microglia can show higher activation during the production of A?? in early AD.