Monoaminergic PET imaging and histopathological correlation in unilateral and bilateral 6-hydroxydopamine lesioned rat models of Parkinson's disease: a longitudinal in-vivo study

Carbon-11 labeled dihydrotetrabenazine (11C-DTBZ) binds to the vesicular monoamine transporter 2 and has been used to assess nigro-striatal integrity in animal models and patients with Parkinson's disease. Here, we applied 11C-DTBZ positron emission tomography (PET) to obtain longitudinally in-vivo assessment of striatal dopaminergic loss in the classic unilateral and in a novel bilateral 6-hydroxydopamine (6-OHDA) lesion rat model. Forty-four Sprague–Dawley rats were divided into 3 sub-groups: 1. 6-OHDA-induced unilateral lesion in the medial forebrain bundle, 2. bilateral lesion by injection of 6-OHDA in the third ventricle, and 3. vehicle injection in either site. 11C-DTBZ PET studies were investigated in the same animals successively at baseline, 1, 3 and 6 weeks after lesion using an anatomically standardized volumes-of-interest approach. Additionally, 12 rats had PET and Magnetic Resonance Imaging to construct a new 11C-DTBZ PET template. Behavior was characterized by rotational, catalepsy and limb-use asymmetry tests and dopaminergic striatal denervation was validated post-mortem by immunostaining of the dopamine transporter (DAT). 11C-DTBZ PET showed a significant decrease of striatal binding (SB) values one week after the unilateral lesion. At this point, there was a 60% reduction in SB in the affected hemisphere compared with baseline values in 6-OHDA unilaterally lesioned animals. A 46% symmetric reduction over baseline SB values was found in bilaterally lesioned rats at the first week after lesion. SB values remained constant in unilaterally lesioned rats whereas animals with bilateral lesions showed a modest (22%) increase in binding values at the 3rd and 6th weeks post-lesion. The degree of striatal dopaminergic denervation was corroborated histologically by DAT immunostaining. Statistical analysis revealed a high correlation between 11C-DTBZ PET SB and striatal DAT immunostaining values (r = 0.95, p < 0.001). The data presented here indicate that 11C-DTBZ PET may be used to ascertain changes occurring in-vivo throughout the evolution of nigro-striatal dopaminergic neurodegeneration, mainly in the unilateral 6-OHDA lesion rat

Statistical parametric maps of (18)F-FDG PET and 3-D autoradiography in the rat brain: a cross-validation study

PURPOSE: Although specific positron emission tomography (PET) scanners have been developed for small animals, spatial resolution remains one of the most critical technical limitations, particularly in the evaluation of the rodent brain. The purpose of the present study was to examine the reliability of voxel-based statistical analysis (Statistical Parametric Mapping, SPM) applied to (18)F-fluorodeoxyglucose (FDG) PET images of the rat brain, acquired on a small animal PET not specifically designed for rodents. The gold standard for the validation of the PET results was the autoradiography of the same animals acquired under the same physiological conditions, reconstructed as a 3-D volume and analysed using SPM. METHODS: Eleven rats were studied under two different conditions: conscious or under inhalatory anaesthesia during (18)F-FDG uptake. All animals were studied in vivo under both conditions in a dedicated small animal Philips MOSAIC PET scanner and magnetic resonance images were obtained for subsequent spatial processing. Then, rats were randomly assigned to a conscious or anaesthetized group for postmortem autoradiography, and slices from each animal were aligned and stacked to create a 3-D autoradiographic volume. Finally, differences in (18)F-FDG uptake between conscious and anaesthetized states were assessed from PET and autoradiography data by SPM analysis and results were compared. RESULTS: SPM results of PET and 3-D autoradiography are in good agreement and led to the detection of consistent cortical differences between the conscious and anaesthetized groups, particularly in the bilateral somatosensory cortices. However, SPM analysis of 3-D autoradiography also highlighted differences in the thalamus that were not detected with PET. CONCLUSION: This study demonstrates that any difference detected with SPM analysis of MOSAIC PET images of rat brain is detected also by the gold standard autoradiographic technique, confirming that this methodology provides reliable results, although partial volume effects might make it difficult to detect slight differences in small regions

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

The progression of dopaminergic depletion in unilateral 6-OHDA-lesioned rats: PET imaging and histopathologic studies. | 8th FENS Forum of Neuroscience (14-18 July 2012. Barcelona, Spain)

Parkinson´s disease(PD) is characterize by a progressive death of dopaminergic neurons in the substantia nigra causing a dopamine depletion in the striatum, which is associated with metabolic compensatory changes. The rat with 6-hydroxydopamine (6-OHDA)-induced lesion in one hemisphere has been widely used as a model of PD. However, the series of pathophysiological and compensatory mechanisms associated with the lesion are not well understood. We performed a neuroimaging study aiming to define the functional changes associated with dopamine striatal depletion. Sprague-Dawley rats were unilaterally lesion using 4µg/4µl and 8µg/4µl of 6-OHDA by intracraneal injection in the median forebrain bundle. PET imaging was performed using a monoaminergic (11C-Dihydrotetrabenazine; 11C-DTBZ) and a metabolic (18F-fluorodeoxyglucose; 18F-FDG) radiotracer and conducted 1 day and 1, 2 , 3 and 6 weeks after the lesion in each animal. Analysis based on regions of interest was done for 11C-DTBZ PET (striatum) and SPM8 analysis for 18F-FDG studies (whole brain). Brains were obtained at the end of the imaging studies and immunostained to reveal optical density measurements of dopamine transporter (DAT) and vesicular monoamine transporter (VMAT2) in the striatum. The 6-OHDA lesion was not associated with a progressive dopaminergic striatal depletion, since DTBZ PET values obtained in the first and sixth weeks were similar (low dose: 65%; high dose: 82%). Pre-synaptic dopamine markers correlated with the striatal binding of 11C-DTBZ. These results suggest that dopamine depletion occurred within the firsts days after the neurotoxin administration. However, dynamic metabolic patterns were evident in both groups of animals. Remarkably, the analysis revealed the 8µg/4µl dose caused a hypometabolism in the somatosensory cortex ipsilateral to lesion (after 2 weeks) and a hypermetabolism in contralateral regions (mainly enthorhinal cortex) related to motor control during evolution. These findings show that this model could provide useful in vivo information about compensatory mechanisms

Upwelling phenomena: the main driver of the latitudinal diversity pattern in Northwest Africa?

Although some depth-related patterns of the continental margin biodiversity are currently understood, the hypothesis that support the latitudinal gradient of species richness increasing from poles to tropics, has only been tested for particular North Atlantic taxa. To date, no systematic and comparative research considering the global zoobenthos at a large regional scale has been undertaken and therefore, the existence of a latitudinal large scale pattern remains uncertain worldwide. Despite the knowledge on benthic biodiversity of Northwest African slope is currently very scarce, some authors pointed out that faunal richness is higher in the upwelling areas than in the tropical regions, being probably less influenced by latitude than by upwelling phenomena and seasonal displacements of thermal fronts occurring in the so-called ‘alternance’ regions. The intensive sampling program following identical methodology in the Canary Current Large Marine Ecosystem region between 2002 and 2012 within the framework of the EcoAfrik and FAO EAF-Nansen projects, offered a unique overview of the biodiversity patterns along the Northwestern African deep-shelf and slope. This approach is based on the taxonomic identification of large collections and the analysis of quantitative data from the benthic invertebrates taken in 1350 trawl stations carried out throughout the 11 research surveys onboard R/V Dr. Fridtjof Nansen and R/V Vizconde de Eza. Preliminary results of these surveys did not show a diversity pattern directly related to latitude along the Northwestern African slope. Specific richness increases significantly along the Moroccan and Saharan coasts, from Cape Spartel (Gibraltar Strait) to Cape Blanc, but decreasing southwards along the Mauritanian continental margin. The highest specific richness values are recorded along the Saharan slope (mean = 36 species by station versus mean = 22–23 species per station in the southern region). The global megabenthic richness and the proportion of suspension-feeders are both higher in the shelf and upper-slope of the temperate area, northern Cape Blanc. The permanence throughout the year of one of the most outstanding upwelling systems of the world and the extension of the giant and high productive Cape Blanc filament to 600 km offshore could maintain these high diversity values even in the deep-sea.MAVA (Contract 12087 Coastal West Africa C4/2012

Monoaminergic and metabolic Positron Emission Tomography of unilateral and bilateral 6-OHDA rat models of Parkinson's disease: a longitudinal in-vivo study. | 15º Congreso Nacional de la Sociedad Española de NeuroCiencia (25-27 de Septiembre de 2013. Oviedo, Spain)

Parkinson´s disease (PD) is characterized by nigro-striatal loss and dopaminergic striatal depletion. The aim of this work is to characterize in-vivo a time-course pattern of functional changes associated with dopaminergic striatal reduction in rat models of PD using Positron Emission Tomography (PET). Forty-four male Sprague-Dawley rats (300-350gr) were used. PET imaging with monoaminergic (11C-(+)-α-dihydrotetrabenazine; 11C-DTBZ) and metabolic (18F-fluorodeoxyglucose; 18F-FDG) radiotracers were performed in a longitudinal study during 6 weeks of the following groups: a) unilaterally lesioned rats by injection of 4µg/4µl (low dose) and 8µg/4µl (high dose) of 6-hydroxydopamine (6-OHDA) in the left median forebrain bundle; and b) bilateral lesion model, in rats receiving intraventricular injection of 100µg/4µl/day of 6-OHDA during 7 days. At the 8th week, the glucose metabolism was also evaluated ex vivo by 18F-FDG autoradiography. Bilaterally lesioned animals were not assessed with metabolic analyses. 11C-DTBZ PET images showed a significant decrease of Striatal Binding (SB) values one week after the lesion (35% SB in the low and 20% SB in the high dose group of unilateral model, and 50% SB in the bilateral model). In the 6th week, no significant differences in these values were found in the unilaterally lesion rats, whereas animals with bilateral lesion showed a higher binding value (65% SB). Remarkably, the metabolic PET study in the unilateral model revealed hypometabolism in ipsilateral somatosensory cortex and hypermetabolism in contralateral entorhinal cortex since the 2nd week onwards. Additionally, the autoradiography analysis showed hypometabolism in bilateral somatosensory cortex and ipsilateral caudate-putamen, motor cortex and thalamus, and also hypermetabolism in the contralateral entorhinal cortex. 11C-DTBZ PET is a sensitive method to ascertain dopaminergic depletion in both the bilateral and, unilateral 6-OHDA rat models. 18F-FDG studies showed a dynamic metabolic pattern that can provide useful in vivo information to monitor brain changes

Monoaminergic PET imaging and histopathological correlation in unilateral and bilateral 6-hydroxydopamine lesioned rat models of Parkinson's disease: a longitudinal in-vivo study

Carbon-11 labeled dihydrotetrabenazine (11C-DTBZ) binds to the vesicular monoamine transporter 2 and has been used to assess nigro-striatal integrity in animal models and patients with Parkinson's disease. Here, we applied 11C-DTBZ positron emission tomography (PET) to obtain longitudinally in-vivo assessment of striatal dopaminergic loss in the classic unilateral and in a novel bilateral 6-hydroxydopamine (6-OHDA) lesion rat model. Forty-four Sprague–Dawley rats were divided into 3 sub-groups: 1. 6-OHDA-induced unilateral lesion in the medial forebrain bundle, 2. bilateral lesion by injection of 6-OHDA in the third ventricle, and 3. vehicle injection in either site. 11C-DTBZ PET studies were investigated in the same animals successively at baseline, 1, 3 and 6 weeks after lesion using an anatomically standardized volumes-of-interest approach. Additionally, 12 rats had PET and Magnetic Resonance Imaging to construct a new 11C-DTBZ PET template. Behavior was characterized by rotational, catalepsy and limb-use asymmetry tests and dopaminergic striatal denervation was validated post-mortem by immunostaining of the dopamine transporter (DAT). 11C-DTBZ PET showed a significant decrease of striatal binding (SB) values one week after the unilateral lesion. At this point, there was a 60% reduction in SB in the affected hemisphere compared with baseline values in 6-OHDA unilaterally lesioned animals. A 46% symmetric reduction over baseline SB values was found in bilaterally lesioned rats at the first week after lesion. SB values remained constant in unilaterally lesioned rats whereas animals with bilateral lesions showed a modest (22%) increase in binding values at the 3rd and 6th weeks post-lesion. The degree of striatal dopaminergic denervation was corroborated histologically by DAT immunostaining. Statistical analysis revealed a high correlation between 11C-DTBZ PET SB and striatal DAT immunostaining values (r = 0.95, p < 0.001). The data presented here indicate that 11C-DTBZ PET may be used to ascertain changes occurring in-vivo throughout the evolution of nigro-striatal dopaminergic neurodegeneration, mainly in the unilateral 6-OHDA lesion rat

Hippocampal synaptic failure is an early event in experimental parkinsonism with subtle cognitive deficit

Learning and memory mainly rely on correct synaptic function in the hippocampus and other brain regions. In Parkinson's disease, subtle cognitive deficits may even precede motor signs early in the disease. Hence, we set out to unravel the earliest hippocampal synaptic alterations associated with human α-synuclein overexpression prior to and soon after the appearance of cognitive deficits in a parkinsonism model. We bilaterally injected adeno-associated viral vectors encoding A53T-mutated human α-synuclein into the substantia nigra of rats, and evaluated them 1, 2, 4 and 16 weeks post-inoculation by immunohistochemistry and immunofluorescence to study degeneration and distribution of α-synuclein in the midbrain and hippocampus. The object location test was used to evaluate hippocampal-dependent memory. Sequential window acquisition of all theoretical mass spectrometry-based proteomics and fluorescence analysis of single-synapse long-term potentiation were used to study alterations to protein composition and plasticity in isolated hippocampal synapses. The effect of L-DOPA and pramipexole on long-term potentiation was also tested. Human α-synuclein was found within dopaminergic and glutamatergic neurons of the ventral tegmental area, and in dopaminergic, glutamatergic and GABAergic axon terminals in the hippocampus from 1 week post-inoculation, concomitant with mild dopaminergic degeneration in the ventral tegmental area. In the hippocampus, differential expression of proteins involved in synaptic vesicle cycling, neurotransmitter release and receptor trafficking, together with impaired long-term potentiation were the first events observed (1 week post-inoculation), preceding cognitive deficits (4 weeks post-inoculation). Later on, at 16 weeks post-inoculation, there was a deregulation of proteins involved in synaptic function, particularly those involved in the regulation of membrane potential, ion balance and receptor signalling. Hippocampal long-term potentiation was impaired before and soon after the onset of cognitive deficits, at 1 and 4 weeks post-inoculation, respectively. L-DOPA recovered hippocampal long-term potentiation more efficiently at 4 weeks post-inoculation than pramipexole, which partially rescued it at both time points. Overall, we found impaired synaptic plasticity and proteome dysregulation at hippocampal terminals to be the first events that contribute to the development of cognitive deficits in experimental parkinsonism. Our results not only point to dopaminergic but also to glutamatergic and GABAergic dysfunction, highlighting the relevance of the three neurotransmitter systems in the ventral tegmental area-hippocampus interaction from the earliest stages of parkinsonism. The proteins identified in the current work may constitute potential biomarkers of early synaptic damage in the hippocampus and hence, therapies targeting these could potentially restore early synaptic malfunction and consequently, cognitive deficits in Parkinson's disease

Long-term protection of HPV test in women at risk of cervical cancer

Objective: To evaluate the 9-year incidence of cervical intraepithelial neoplasia grade 2 or worse (CIN2+) and cumulative adherence to perform a next test in a cohort of women aged 40+ years with no cervical screening cytology within a window of 5 years (underscreened women), after baseline cervical cytology and HPV tests. Methods: In Catalonia, Spain, co-testing with cytology and HPV test has been recommended in the Public Health system since 2006 for underscreened women. In 2007, 1,594 women with underscreened criteria were identified and followed through medical records form Pathological Department. 9-year cumulative incidence of histologically confirmed CIN2+ and cumulative adherence to perform a next test were estimated using Kaplan-Meier statistics. Results: Follow-up was available for 1,009 women (63.3%) resulting in 23 women with. CIN2+ (2.3%). Of them, 4 women (17%) had both tests negative at baseline (3CIN2 and 1CIN3) with cumulative incidence of CIN2+ of 0.4% (95% CI: 0.1-1.4) at 5-years and 1.3% (95% CI: 0.4-3.7) at 9-years. During the first year, the prevalence among women with both tests positive was 27.0% (95% CI: 13.0-50.6) for CIN2+. Lost to follow-up was higher among women with both tests negative compared to those with both positive tests (38.7% vs 4.2%, p-value <0.001). 40.5% of the women HPV-/cyto- had a re-screening test during the 4 years following the baseline, increasing until 53.5% during the 6 years of follow-up. Conclusions: HPV detection shows a high longitudinal predictive value at 9-year to identify women at risk to develop CIN2+. The data validate a safe extension of the 3-year screening intervals (current screening interval) to 5-year intervals in underscreened women that had negative HPV result at baseline. It is necessary to establish mechanisms to ensure screening participation and adequate follow-up for these women

Exome sequencing identifies breast cancer susceptibility genes and defines the contribution of coding variants to breast cancer risk

Funder: Genome Canada (Génome Canada); doi: https://doi.org/10.13039/100008762Funder: Cancer Research UK (CRUK); doi: https://doi.org/10.13039/501100000289Linkage and candidate gene studies have identified several breast cancer susceptibility genes, but the overall contribution of coding variation to breast cancer is unclear. To evaluate the role of rare coding variants more comprehensively, we performed a meta-analysis across three large whole-exome sequencing datasets, containing 26,368 female cases and 217,673 female controls. Burden tests were performed for protein-truncating and rare missense variants in 15,616 and 18,601 genes, respectively. Associations between protein-truncating variants and breast cancer were identified for the following six genes at exome-wide significance (P < 2.5 × 10−6): the five known susceptibility genes ATM, BRCA1, BRCA2, CHEK2 and PALB2, together with MAP3K1. Associations were also observed for LZTR1, ATRIP and BARD1 with P < 1 × 10−4. Associations between predicted deleterious rare missense or protein-truncating variants and breast cancer were additionally identified for CDKN2A at exome-wide significance. The overall contribution of coding variants in genes beyond the previously known genes is estimated to be small