Orbital Apex Syndrome Resulting from Mixed Bacterial Sphenoid Sinusitis

Orbital apex syndrome (OAS) is an uncommon disorder characterized by visual loss, ophthalmoplegia, ptosis and hypoaesthesia of the forehead[1]. OAS may result from a variety of inflammatory, infectious, neoplastic and vascular conditions that cause damage to the superior orbital fissure (with resultant oculomotor (III), trochlear (IV), abducens (VI) and ophthalmic branch of the trigeminal nerve (V1) palsies) and to the optic canal leading to optic nerve (II) dysfunction. This case report describes the clinical development of OAS in a patient with bacterial sphenoid sinusitis

The Chemogenetic Receptor Ligand Clozapine N-Oxide Induces<em> in vivo</em> Neuroreceptor Occupancy and Reduces Striatal Glutamate Levels

Chemogenetic studies with the ligand clozapine N-oxide (CNO) are predicated upon the assumption that CNO is devoid of actions at natural neuroreceptors. However, recent evidence shows that CNO may be converted back to clozapine (CLZ) in vivo, which could yield plasma concentrations that may be sufficient to occupy inter alia dopamine D2=3 and serotonin 5HT2A receptors in living brain. To test this phenomenon, we measured striatal dopamine D2=3 receptor occupancy with [18F]fallypride PET and serotonin 5HT2A occupancy ex vivo using [18F]MH.MZ. We found a CNO dosedependent effect on the availability of both neuroreceptor sites. In parallel MR spectroscopy experiments, we found that CNO reduced creatine C phosphcreatine (CrCPCr) and increased N-acetylaspartate C N-acetylaspartylglutamate (NAACNAAG) signals in the prefrontal cortex, and also reduced the glutamate signal in dorsal striatum, with peak effect at 2 mg/kg. Thus, our findings suggest that conversion of CNO to CLZ in living rats imparts significant occupancy at endogenous neuroreceptors and significant changes to neurometabolite levels

The Chemogenetic Receptor Ligand Clozapine N-Oxide Induces in vivo Neuroreceptor Occupancy and Reduces Striatal Glutamate Levels

Chemogenetic studies with the ligand clozapine N-oxide (CNO) are predicated upon the assumption that CNO is devoid of actions at natural neuroreceptors. However, recent evidence shows that CNO may be converted back to clozapine (CLZ) in vivo, which could yield plasma concentrations that may be sufficient to occupy inter alia dopamine D2/3 and serotonin 5HT2A receptors in living brain. To test this phenomenon, we measured striatal dopamine D2/3 receptor occupancy with [18F]fallypride PET and serotonin 5HT2A occupancy ex vivo using [18F]MH.MZ. We found a CNO dose-dependent effect on the availability of both neuroreceptor sites. In parallel MR spectroscopy experiments, we found that CNO reduced creatine + phosphcreatine (Cr+PCr) and increased N-acetylaspartate + N-acetylaspartylglutamate (NAA+NAAG) signals in the prefrontal cortex, and also reduced the glutamate signal in dorsal striatum, with peak effect at 2 mg/kg. Thus, our findings suggest that conversion of CNO to CLZ in living rats imparts significant occupancy at endogenous neuroreceptors and significant changes to neurometabolite levels

Visualising neurodegeneration in the living brain : Preclinical evaluation of PET radioligands

With an ageing population, the number of people suffering from Alzheimer’s disease (AD) and Parkinson’s disease (PD) escalates yearly. Pathological hallmarks of AD and PD include aggregated proteins and synaptic dysfunction. Developing imaging probes targeting specific pathological hallmarks is highly valuable in aiding early diagnosis and treatment assessment. The thesis focused on evaluating positron emission tomography (PET) imaging probes that can visualise different pathological changes in preclinical models of neurodegeneration. Ligands targeting synaptic vesicle protein 2A (SV2A), alpha-synuclein (αSyn), and amyloid-beta (Aβ) are investigated. In paper I, we compared synaptic density in transgenic AD and PD mouse models to their wild-type age-matched controls using SV2A PET. In the hippocampus, lower synaptic density was found in the PD mice compared to the control. In paper II, we continued using SV2A PET and studied synaptic density in ageing mice. Synaptic density remained steady for most of the lifespan but slightly decreased in old age. In paper III, we developed and evaluated five antibody-based PET radioligands targeting αSyn aggregates. By conjugating anti-αSyn antibodies with the transferrin receptor (TfR) binder 8D3, we increased antibody brain entry significantly. These bispecific antibodies displayed high specificity and selectivity to αSyn aggregates. The most promising candidate successfully imaged brain-deposited αSyn but was unable to detect endogenously expressed αSyn in PD mouse models. In light of this, further investigation of antibody brain entry, distribution, and elimination is needed. Thus, in paper IV, we used microdialysis to compare the brain pharmacokinetics of a bispecific antibody targeting TfR and Aβ and its regular monospecific version that only binds to Aβ. The bispecific antibody showed distinct pharmacokinetics and entered the brain more efficiently than the regular antibody. Lastly, in paper V, we studied the impact of anti-Aβ antibody treatment on amyloid PET. AD mice were short-term treated with anti-Aβ antibody mAb158 and underwent [11C]PiB ex vivo autoradiography. We found a trend indicating that the treatment reduced the [11C]PiB signal despite no reduction in total Aβ levels. Our results contribute to an increased understanding of PET radioligands imaging neurodegeneration. Furthermore, it provides valuable information for designing and developing new PET radioligands

Visualising neurodegeneration in the living brain : Preclinical evaluation of PET radioligands

With an ageing population, the number of people suffering from Alzheimer’s disease (AD) and Parkinson’s disease (PD) escalates yearly. Pathological hallmarks of AD and PD include aggregated proteins and synaptic dysfunction. Developing imaging probes targeting specific pathological hallmarks is highly valuable in aiding early diagnosis and treatment assessment. The thesis focused on evaluating positron emission tomography (PET) imaging probes that can visualise different pathological changes in preclinical models of neurodegeneration. Ligands targeting synaptic vesicle protein 2A (SV2A), alpha-synuclein (αSyn), and amyloid-beta (Aβ) are investigated. In paper I, we compared synaptic density in transgenic AD and PD mouse models to their wild-type age-matched controls using SV2A PET. In the hippocampus, lower synaptic density was found in the PD mice compared to the control. In paper II, we continued using SV2A PET and studied synaptic density in ageing mice. Synaptic density remained steady for most of the lifespan but slightly decreased in old age. In paper III, we developed and evaluated five antibody-based PET radioligands targeting αSyn aggregates. By conjugating anti-αSyn antibodies with the transferrin receptor (TfR) binder 8D3, we increased antibody brain entry significantly. These bispecific antibodies displayed high specificity and selectivity to αSyn aggregates. The most promising candidate successfully imaged brain-deposited αSyn but was unable to detect endogenously expressed αSyn in PD mouse models. In light of this, further investigation of antibody brain entry, distribution, and elimination is needed. Thus, in paper IV, we used microdialysis to compare the brain pharmacokinetics of a bispecific antibody targeting TfR and Aβ and its regular monospecific version that only binds to Aβ. The bispecific antibody showed distinct pharmacokinetics and entered the brain more efficiently than the regular antibody. Lastly, in paper V, we studied the impact of anti-Aβ antibody treatment on amyloid PET. AD mice were short-term treated with anti-Aβ antibody mAb158 and underwent [11C]PiB ex vivo autoradiography. We found a trend indicating that the treatment reduced the [11C]PiB signal despite no reduction in total Aβ levels. Our results contribute to an increased understanding of PET radioligands imaging neurodegeneration. Furthermore, it provides valuable information for designing and developing new PET radioligands

Brain pharmacokinetics of mono- and bispecific amyloid-beta antibodies in wild-type and Alzheimer's disease mice measured by high cut-off microdialysis

Background: Treatment with amyloid-beta (A beta) targeting antibodies is a promising approach to remove A beta brain pathology in Alzheimer's disease (AD) and possibly even slow down or stop progression of the disease. One of the main challenges of brain immunotherapy is the restricted delivery of antibodies to the brain. However, bispecific antibodies that utilize the transferrin receptor (TfR) as a shuttle for transport across the blood-brain barrier (BBB) can access the brain better than traditional monospecific antibodies. Previous studies have shown that bispecific A beta targeting antibodies have higher brain distribution, and can remove A beta pathology more efficiently than monospecific antibodies. Yet, there is only limited information available on brain pharmacokinetics, especially regarding differences between mono- and bispecific antibodies. Methods: The aim of the study was to compare brain pharmacokinetics of A beta-targeting monospecific mAb3D6 and its bispecific version mAb3D6-scFv8D3 that also targets TfR. High cut-off microdialysis was used to measure intravenously injected radiolabelled mAb3D6 and mAb3D6-scFv8D3 antibodies in the interstitial fluid (ISF) of hippocampus in wild-type mice and the App(NL-G-F) mouse model of AD. Distribution of the antibodies in the brain and the peripheral tissue was examined by ex vivo autoradiography and biodistribution studies. Results: Brain concentrations of the bispecific antibody were elevated compared to the monospecific antibody in the hippocampal ISF measured by microdialysis and in the brain tissue at 4-6 h after an intravenous injection. The concentration of the bispecific antibody was approximately twofold higher in the ISF dialysate compared to the concentration of monospecific antibody and eightfold higher in brain tissue 6 h post-injection. The ISF dialysate concentrations for both antibodies were similar in both wild-type and App(NL-G-F) mice 24 h post-injection, although the total brain tissue concentration of the bispecific antibody was higher than that of the monospecific antibody at this time point. Some accumulation of radioactivity around the probe area was observed especially for the monospecific antibody indicating that the probe compromised the BBB to some extent at the probe insertion site. Conclusion: The BBB-penetrating bispecific antibody displayed higher ISF concentrations than the monospecific antibody. The concentration difference between the two antibodies was even larger in the whole brain than in the ISF. Further, the bispecific antibody, but not the monospecific antibody, displayed higher total brain concentrations than ISF concentrations, indicating association to brain tissue

Genome-wide identification, molecular evolution, and expression analysis of auxin response factor (ARF) gene family in Brachypodium distachyon L

Abstract Background The auxin response factor (ARF) gene family is involved in plant development and hormone regulation. Although the ARF gene family has been studied in some plant species, its structural features, molecular evolution, and expression profiling in Brachypodium distachyon L. are still not clear. Results Genome-wide analysis identified 19 ARF genes in B. distachyon. A phylogenetic tree constructed with 182 ARF genes from seven plant species revealed three different clades, and the ARF genes from within a clade exhibited structural conservation, although certain divergences occurred in different clades. The branch-site model identified some sites where positive selection may have occurred, and functional divergence analysis found more Type II divergence sites than Type I. In particular, both positive selection and functional divergence may have occurred in 241H, 243G, 244 L, 310 T, 340G and 355 T. Subcellular localization prediction and experimental verification indicated that BdARF proteins were present in the nucleus. Transcript expression analysis revealed that BdARFs were mainly expressed in the leaf and root tips, stems, and developing seeds. Some BdARF genes exhibited significantly upregulated expression under various abiotic stressors. Particularly, BdARF4 and BdARF8 were significantly upregulated in response to abiotic stress factors such as salicylic acid and heavy metals. Conclusion The ARF gene family in B. distachyon was highly conserved. Several important amino acid sites were identified where positive selection and functional divergence occurred, and they may play important roles in functional differentiation. BdARF genes had clear tissue and organ expression preference and were involved in abiotic stress response, suggesting their roles in plant growth and stress resistance

In vivo imaging of synaptic density with [C-11]UCB-J PET in two mouse models of neurodegenerative disease

The positron emission tomography (PET) radioligand [C-11]UCB-J binds to synaptic vesicle protein 2A (SV2A) and is used to investigate synaptic density in the living brain. Clinical studies have indicated reduced [C-11]UCB-J binding in Alzheimer's disease (AD) and Parkinson's disease (PD) brains compared to healthy controls. Still, it is unknown whether [C-11]UCB-J PET can visualise synaptic loss in mouse models of these disorders. Such models are essential for understanding disease pathology and for evaluating the effects of novel disease-modifying drug candidates. In the present study, synaptic density in transgenic models of AD (ArcSwe) and PD (L61) was stud-ied using [C-11]UCB-J PET. Data were acquired during 60 min after injection, and time-activity curves (TACs) in different brain regions and the left ventricle of the heart were generated based on the dynamic PET images. The [C-11]UCB-J brain concentrations were expressed as standardised uptake value (SUV) over time. The area under the SUV curve (AUC), the ratio of AUC in the brain to that in the heart (AUCbrain/blood), and the volume of distribution (VT) obtained by kinetic modelling using the heart TAC as input were compared between trans-genic and age-matched wild type (WT) mice. The L61 mice displayed 11-13% lower AUCbrain/blood ratio and brain VT generated by kinetic modeling compared to the control WT mice. In general, also transgenic ArcSwe mice tended to show lower [C-11]UCB-J brain exposure than age-matched WT controls, but variation within the different animal groups was high. Older WT mice (18-20 months) showed lower [C-11]UCB-J brain exposure than younger WT mice (8-9 months). Together, these data imply that [C-11]UCB-J PET reflects synaptic density in mouse models of neurodegeneration and that inter-subject variation is large. In addition, the study suggested that model-independent AUCbrain/blood ratio can be used to evaluate [C-11]UCB-J binding as an alternative to full pharmacokinetic modelling