Digital autoradiography for efficient functional imaging without anesthesia in experimental animals : Reversing phencyclidine-induced functional alterations using clozapine

Autoradiography (ARG) is a high-resolution imaging method for localization of radiolabeled biomarkers in ex vivo specimen. ARG using 2-deoxy-D-glucose (2-DG) method is used in to study drug actions on brain functional activity, as it provides results comparable to clinically used functional positron-emission tomography (PET). The requirement of slow analog detection methods and emerging advances in small animal PET imaging have, however, reduced the interest in ARG. In contrast to ARG, experimental animals need to be restrained or sedated/anesthetized for PET imaging, which strongly influence functional activity and thus complicate the interpretation of the results. Digital direct particle-counting ARG systems have gained attraction during the last decade to overcome the caveats of conventional ARG methods. Here we demonstrate that the well-established 2-DG imaging method can be adapted into use with contemporary digital detectors. This method readily and rapidly captures the characteristic effects of phencyclidine (5 mg/kg, i.p.), a dissociative agent targeting the NMDAR (N-methyl-D-aspartate receptor), on regional glucose utilization in the adult mouse brain. Pretreatment with antipsychotic drug clozapine (6 mg/kg, i.p.) essentially abolishes these effects of phencyclidine on brain functional activity. Digital ARG produces viable data for the regional analysis of functional activity in a fraction of time required for film development. These results support the use of digital ARG in preclinical drug research, where high throughput and response linearity are preferred and use of sedation/anesthesia has to be avoided.Peer reviewe

Concept of an Upright Wearable Positron Emission Tomography Imager in Humans

Background: Positron Emission Tomography (PET) is traditionally used to image patients in restrictive positions, with few devices allowing for upright, brain-dedicated imaging. Our team has explored the concept of wearable PET imagers which could provide functional brain imaging of freely moving subjects. To test feasibility and determine future considerations for development, we built a rudimentary proof-of-concept prototype (Helmet_PET) and conducted tests in phantoms and four human volunteers. Methods: Twelve Silicon Photomultiplier-based detectors were assembled in a ring with exterior weight support and an interior mechanism that could be adjustably fitted to the head. We conducted brain phantom tests as well as scanned four patients scheduled for diagnostic F18-FDG PET/CT imaging. For human subjects the imager was angled such that field of view included basal ganglia and visual cortex to test for typical resting-state pattern. Imaging in two subjects was performed ~4 hr after PET/CT imaging to simulate lower injected F18-FDG dose by taking advantage of the natural radioactive decay of the tracer (F18 half-life of 110 min), with an estimated imaging dosage of 25% of the standard. Results: We found that imaging with a simple lightweight ring of detectors was feasible using a fraction of the standard radioligand dose. Activity levels in the human participants were quantitatively similar to standard PET in a set of anatomical ROIs. Typical resting-state brain pattern activation was demonstrated even in a 1 min scan of active head rotation. Conclusion: To our knowledge, this is the first demonstration of imaging a human subject with a novel wearable PET imager that moves with robust head movements. We discuss potential research and clinical applications that will drive the design of a fully functional device. Designs will need to consider trade-offs between a low weight device with high mobility and a heavier device with greater sensitivity and larger field of view

Multimodal view on resting-state brain activity in Parkinson’s disease: examining the relation between functional resting-state networks and metabolic network activity

Research focusing on the pathophysiology of neurodegenerative disorders has undergone a fundamental shift towards a network perspective in the last decades. Besides regional aggregation of misfolded proteins and changes in cellular metabolism, accompanying changes of synaptic activity evolve and evoke dysregulation within neural circuits including remote brain regions. Modern theories of neurodegeneration propose a stereotypic pattern of these cerebral pathologies, which partly are in vivo accessible by multimodal neuroimaging techniques. The most often used indirect measurement of functional network integrity is resting-state functional magnetic resonance imaging, which depends on a complex interplay of hemodynamics, blood volume, and blood flow. Less is known about a potential metabolic component underlying resting-state networks in healthy brains and changes thereof in neurodegeneration and the influence of different transmitter systems. The current work therefore sought to investigate the association between functional resting-state networks and metabolic network activity and focused on metabolic consequences of nigrostriatal and striatocortical dysfunction in Parkinson’s disease. In the current work, a multimodal data set of the TP10 KFO219 cohort was analyzed regarding 1) the impact of nigrostriatal dopamine depletion on resting-state networks and 2) the relation between changes in functional connectivity and metabolic network activity. The first study addressed the subset of the KFO219 TP10 cohort who completed the trimodal imaging protocol (42 patients vs. 14 controls). Dopamine deficiency in Parkinson’s patients was examined by voxel-wise comparison of 6-[18F]fluoro-L-Dopa positron emission tomography scans. Resulting clusters served as seeds for restingstate functional connectivity maps that were compared between both groups by voxelwise t-tests. Metabolic activity was extracted from 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography scans for respective cortical clusters with striatocortical dysconnectivity and the relation to functional connectivity values was analyzed. In a separate study, functional and metabolic resting-state networks were obtained by performing spatial independent component analyses in a subset of the same cohort who underwent 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography and functional magnetic resonance imaging (56 vs 16) and completed neuropsychological testing. Multimodally obtained regions of interest in the default mode network were defined and metabolic activity as well as metabolic connectivity compared to functional connectivity differences between patients without or with mild cognitive impairment and healthy controls. Moreover, a third study was initiated in the context of the present work with the aim of establishing a dynamic 2-[18F]fluoro-2-deoxy-D-glucose positronemission tomography acquisition with a constant infusion protocol for examining interregional metabolic connectivity on single subject level and enable comparable analysis of hemodynamic and metabolic fluctuations in Parkinson’s disease. In the first study, a significant association between striatocortical functional connectivity changes of the data-driven defined dopamine depleted posterior putamen and metabolic activity of the cortical target area in the inferior parietal cortex was found in Parkinson’s disease. Interestingly, striatocortical connectivity of the inferior parietal cortex was associated with motor and cognitive impairment. In a second study, the multivariate approach revealed a moderate spatial convergence for the posterior default mode network in functional and metabolic data. For all multimodally obtained default mode network regions, a significant trend towards an increment of metabolic deficits from healthy controls via unimpaired patients to patients with mild cognitive impairment was identified. In addition, posterior default mode network regions with the strongest metabolic deficits and gradual decline in comparison to controls, also showed the strongest increases in both metabolic and functional connectivity compared to controls. The verification of the applicability of a constant infusion dynamic 2-[18F]fluoro-2-deoxy- D-glucose positron emission tomography protocol in Parkinson’s disease patients was started in a self-initiated study, which finished the acquisition phase with 10 participants per group by the time the current work was submitted. Together the first two studies highlight the added value of multimodal imaging in investigating human brain function and the pathophysiology of neurodegenerative disorders, in particular their great potential for identifying links between individual pathologies. The second study partly continued, and answered questions raised in response to the first study, which hinted at an involvement of default mode network regions in cognitive symptoms of Parkinson’s disease and a relation between functional network degeneration and metabolic activity. The current work shows exemplary the complementarity of both measures of brain network activity and their individual significance for cognitive symptoms in Parkinson’s disease. The presented work highlights how multimodal resting-state studies can provide new insights into the (patho-)physiological network organization of brain activity by confirming insights obtained by one modality and deepen our understanding of disease processes. The selfinitiated study further laid the ground for multimodal characterization of metabolic and hemodynamic network changes on single-subject level and the evaluation of dynamic positron emission tomography-based connectivity as metabolic network marker for Parkinson’s disease

Investigating tumor perfusion, glycolysis and pH environments with multimodal in vivo imaging

Background: Cancer cells have a complex microenvironment that helps create optimal conditions for cancer proliferation. Nutrients such as glucose will pass through a tortuous and leaky vascular structure developed by cancer cells, and are subsequently distributed and transported inside the cancer cells to meet their metabolic demands. This leaky and poorly organized vasculature leads to a buildup in the interstitial fluid pressure surrounding the tumor, subsequently resulting in tumor hypoxia. Due to an overreliance on glycolysis, more acid and protons are produced by cancer cells, leading to a more acidic environment which, in combination with tumor hypoxia, often leads to a poor patient outcome. This thesis aims to explore the intrinsic relationship between tumor perfusion, glycolysis and its pH environment using a C6 rat model of glioma. Methods: All subjects were implanted with 1 million C6 glioma cells using stereotactic surgery. The growth of tumor cells was monitored either with computed tomography perfusion (CTP) or magnetic resonance imaging (MRI). Once tumors had reached the optimal size, tumor perfusion was measured using CTP. Tumor glycolytic metabolism was measured using positron emission tomography (PET) with 18F-flurodeoxyglucose (FDG) and MR spectroscopy imaging (MRSI) using hyperpolarized [1-13C]pyruvate. Chemical exchange saturation (CEST) MRI was also used to investigate tumor glucose distribution (glucose contrast enhancement, or ∆CEST) and pH environments (intra-/extracellular pH, pHi and pHe respectively and simultaneously) during/after a glucose infusion/injection. All experimental procedures were completed within 24 hours. Measurements of tumor perfusion, glycolysis, ∆CEST and pH environments were correlated using Pearson’s correlation. Results: Tumor perfusion measurement of permeability surface-area product (PS) was significantly correlated with tumor glycolysis measurement of Lac:Pyr from hyperpolarized MRSI as well as ∆CEST. Tumor Lac:Pry was also significantly correlated with tumor pHi. Tumor metabolic rate of glucose derived from dynamic PET was significantly correlated with tumor pHi and pHe. Conclusion: This research showed the possibility of measuring the intracellular and extracellular pH environment simultaneously. Multimodal imaging approaches provided a more complete picture of the tumor microenvironment and helped elucidate the intrinsic relationship between tumor perfusion, glycolysis and the pH environment

Measuring inflammation in the entire myocardium in a canine model of myocardial infarction with hybrid PET/MRI

Background: After myocardial infarction (MI), fibrosis and an ongoing dysregulated inflammatory response are associated with adverse cardiac remodeling. Fluorodeoxyglucose (FDG) positron emission tomography (PET) is sensitive to inflammation provided suppression protocols are implemented to restrict the uptake of glucose in myocytes. Magnetic resonance imaging can be used to determine extracellular volume, a surrogate measure of fibrosis. In some cases, patients present with markedly reduced flow in the setting of a large infarct, i.e. microvascular obstruction, restricting the delivery of FDG and contrast agents. To overcome this problem, a constant infusion was explored as an alternative to the clinical standard bolus injection. This led to three objectives: a) comparison of the constant infusion to the bolus injection in healthy canines, b) investigation of the potential of the constant infusion to discriminate post-MI tissue types, and c) determination of the efficacy of the suppression protocol and its effect on extracellular volume. Methods: All imaging was done with a hybrid PET/MRI scanner. MRI images were used to determine the regions of interest: remote, injured and obstructed myocardium. PET images were used to determine inflammation. To compare the injection strategies, five healthy canines were examined with all three. Subsequently, eight animals were imaged at baseline and days 3, 7, 14, 21, and 42 post-MI using a 60-min infusion. Lastly, seven animals were imaged at baseline and day 5 post-MI using a 150-min infusion. Forty minutes into the infusion, suppression of glucose uptake in myocytes was started. Results: No significant differences in terms of glucose metabolism and extracellular volume were seen in healthy myocardium between the three injection strategies: bolus injection, constant infusion and bolus followed by constant infusion, showing that a strategy involving the constant infusion produced similar results as to those obtained with a bolus injection. Following MI, a significant increase in extracellular volume was seen in remote tissue on days 14 and 21, suggesting an inflammatory response. During the 150-min infusion, suppression of myocardial glucose uptake had the unexpected result of reducing FDG uptake in inflammatory cells within the infarcted area. Conclusion: This research showed the possibility of using a constant infusion of Gd-DTPA and FDG to investigate inflammation within the entire myocardium. The finding that suppression affected inflammatory cells highlights the need for tracers which do not rely on myocardial glucose suppression

Diagnostic Significance of Exosomal miRNAs in the Plasma of Breast Cancer Patients

Poster Session AbstractsBackground and Aims: Emerging evidence that microRNAs (miRNAs) play an important role in cancer development has opened up new opportunities for cancer diagnosis. Recent studies demonstrated that released exosomes which contain a subset of both cellular mRNA and miRNA could be a useful source of biomarkers for cancer detection. Here, we aim to develop a novel biomarker for breast cancer diagnosis using exosomal miRNAs in plasma. Methods: We have developed a rapid and novel isolation protocol to enrich tumor-associated exosomes from plasma samples by capturing tumor specific surface markers containing exosomes. After enrichment, we performed miRNA profiling on four sample sets; (1) Ep-CAM marker enriched plasma exosomes of breast cancer patients; (2) breast tumors of the same patients; (3) adjacent non-cancerous tissues of the same patients; (4) Ep-CAM marker enriched plasma exosomes of normal control subjects. Profiling is performed using PCR-based array with human microRNA panels that contain more than 700 miRNAs. Results: Our profiling data showed that 15 miRNAs are concordantly up-regulated and 13 miRNAs are concordantly down-regulated in both plasma exosomes and corresponding tumors. These account for 25% (up-regulation) and 15% (down-regulation) of all miRNAs detectable in plasma exosomes. Our findings demonstrate that miRNA profile in EpCAM-enriched plasma exosomes from breast cancer patients exhibit certain similar pattern to that in the corresponding tumors. Based on our profiling results, plasma signatures that differentiated breast cancer from control are generated and some of the well-known breast cancer related miRNAs such as miR-10b, miR-21, miR-155 and miR-145 are included in our panel list. The putative miRNA biomarkers are validated on plasma samples from an independent cohort from more than 100 cancer patients. Further validation of the selected markers is likely to offer an accurate, noninvasive and specific diagnostic assay for breast cancer. Conclusions: These results suggest that exosomal miRNAs in plasma may be a novel biomarker for breast cancer diagnosis.link_to_OA_fulltex

Internet and Biometric Web Based Business Management Decision Support

Internet and Biometric Web Based Business Management Decision Support MICROBE MOOC material prepared under IO1/A5 Development of the MICROBE personalized MOOCs content and teaching materials Prepared by: A. Kaklauskas, A. Banaitis, I. Ubarte Vilnius Gediminas Technical University, Lithuania Project No: 2020-1-LT01-KA203-07810

Some systemic markers of inflammation in older adults with psychiatric disorders

Research has demonstrated that inflammation is a central part of several psychiatric disorders, of which depression in the most researched condition. Most studies have, however, been conducted on younger adults, and studies on elderly are scarce. This thesis explores the possible association between systemic markers of inflammation and characteristics of older psychiatric patients. In study I, we investigated possible correlations between the levels of 27 cytokines in plasma, and clinical and demographical variables, in diagnostically unselected in-patients that were 60 years and older (N = 98). We found no significant associations between cytokine levels and diagnoses, nor any other variables. However, we did find higher levels of 10 cytokines in the non-depressed patients, possibly as a result of the higher prevalence of cardiovascular disease and dementia. In study II, we explored whether changes in the level of 27 cytokines plasma during the treatment of diagnostically unselected psychiatric in-patients aged 60 years or more (N = 49) could be related to clinical and demographical variables, as well as self-reported clinical improvement. We found a positive correlation between clinical improvement and falling cytokine levels (p < 0.033), irrespective of psychiatric diagnoses or other variables. In study III, we investigated possible correlations between two levels of depression - moderate and moderate-severe depression - and CRP in serum, in younger (40 - 59 years) versus older adults (≥ 60 years) (N = 19,947). We found a multi-adjusted association between depression and elevated CRP in younger adults, but not in older adults. The studies of this thesis could not confirm an association between markers of systemic inflammation, and diagnoses and other characteristics of older adults with psychiatric disorders. In particular, this research could not, unlike most studies on younger adults, confirm a link between markers of systemic inflammation and depression in older adults.Depresjon – en betent sak? Betennelse er kroppens generelle respons på sykdom og skade. For eksempel svarer kroppen med betennelse når vi angripes av et virus eller får et spark på leggen. Ved en betennelse frigjøres betennelsesstoffer fra stedet hvor infeksjonen eller skaden er. Disse stoffene fungerer som kallesignaler for de hvite blodlegemene og gjør at blodgjennom-strømmingen øker, slik at kroppens forvar kommer i gang. For å finne ut om man har en betennelse i kroppen kan man undersøke mengden av betennelsesstoffer i blodet, som for eksempel CRP eller såkalte cytokiner. CRP produseres i leveren og cytokinene produseres av immuncellene. Forskning har vist at det kan oppstå betennelse i kroppen også når vi rammes av en psykisk lidelse. Det man har forsket mest på er depresjon. Her viser forskningen at deprimerte personer har økte nivåer av betennelsesstoffer i blodet. Man har også funnet at mengden av betennelsesstoffer samsvarer med hvor deprimert man er, og hvilken prognose man har. Det aller meste av forskningen på dette feltet er utført på yngre voksne. Eldre voksne, dvs. personer som er 60-65 år eller eldre, er sjelden inkludert i forskningen. Forskningen vår fokusert spesielt på eldre. Vi har sett på om det er sammenheng mellom betennelsesstoffer og ulike psykiske lidelser, spesielt depresjon, hos personer som er 60 år og eldre. I denne forskningen inngår to studier av eldre pasienter innlagt ved en alderspsykiatrisk avdeling, og én befolkningsstudie (den syvende Tromsøundersøkelsen). Resultantene viser at det ikke er noen sikker sammenheng mellom psykisk lidelser og betennelse hos eldre. Det er særlig interessant at man ikke finner noen sammenheng mellom depresjon og betennelse hos eldre, noe som skiller seg fra tilsvarende forskning på yngre personer. En mulig grunn til dette er at immunsystemet til eldre oppfører seg annerledes enn hos yngre