| 1. |
- Hagberg, Carolina E, et al.
(författare)
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Vascular endothelial growth factor B controls endothelial fatty acid uptake.
- 2010
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 464:7290, s. 917-21
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Tidskriftsartikel (refereegranskat)abstract
- The vascular endothelial growth factors (VEGFs) are major angiogenic regulators and are involved in several aspects of endothelial cell physiology. However, the detailed role of VEGF-B in blood vessel function has remained unclear. Here we show that VEGF-B has an unexpected role in endothelial targeting of lipids to peripheral tissues. Dietary lipids present in circulation have to be transported through the vascular endothelium to be metabolized by tissue cells, a mechanism that is poorly understood. Bioinformatic analysis showed that Vegfb was tightly co-expressed with nuclear-encoded mitochondrial genes across a large variety of physiological conditions in mice, pointing to a role for VEGF-B in metabolism. VEGF-B specifically controlled endothelial uptake of fatty acids via transcriptional regulation of vascular fatty acid transport proteins. As a consequence, Vegfb(-/-) mice showed less uptake and accumulation of lipids in muscle, heart and brown adipose tissue, and instead shunted lipids to white adipose tissue. This regulation was mediated by VEGF receptor 1 and neuropilin 1 expressed by the endothelium. The co-expression of VEGF-B and mitochondrial proteins introduces a novel regulatory mechanism, whereby endothelial lipid uptake and mitochondrial lipid use are tightly coordinated. The involvement of VEGF-B in lipid uptake may open up the possibility for novel strategies to modulate pathological lipid accumulation in diabetes, obesity and cardiovascular diseases.
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| 2. |
- Manouilenko, Irina, et al.
(författare)
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Autistic traits, ADHD symptoms, neurological soft signs and regional cerebral blood flow in adults with autism spectrum disorders
- 2013
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Ingår i: Research in Autism Spectrum Disorders. - Oxon, United Kingdom : Elsevier. - 1750-9467 .- 1878-0237. ; 7, s. 566-578
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Tidskriftsartikel (refereegranskat)abstract
- The resting regional cerebral blood flow (rCBF) patterns related to co-occurring symptoms such as inattention, hyperactivity, neurological soft signs and motor problems have not yet been disclosed in autism spectrum disorders (ASD). In this study thirteen adults with ASD and ten matched neurotypical controls underwent PET. The scores of rating scales for autistic traits, attention deficit hyperactivity disorder (ADHD) and neurological soft signs were included in a factorial analysis and correlated with rCBF. Factors corresponding to “autistic/ADHD traits”, “sensory-motor integration” and “intelligence/motor sequencing” were identified. In the ASD group, positive correlations with CBF were found for “autistic/ADHD traits” in caudate bilaterally and the inferior parietal lobule, for “sensory-motor integration” in parieto-occipital cortex and for “intelligence/motor sequencing” in the right temporal cortex. Notably, CBF in the left thalamus correlated negatively with all three factors. Autistic traits and ADHD symptoms were associated with shared neural substrates. The correlation between “autistic/ADHD traits” and rCBF in the caudate is possibly associated with the executive impairments and ritualistic/stereotyped behaviors apparent in ASD. Furthermore, sensory-motor deficits were correlated with rCBF in the occipital visual cortex, involved in atypical visual perception in ASD. Various behavioral and neurological symptoms are suggested to converge into the ASD phenotype.
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| 3. |
- Pagani, Marco, et al.
(författare)
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Brief Report : alterations in cerebral blood flow as assessed by PET/CT in adults with autism spectrum disorder with normal IQ
- 2012
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Ingår i: Journal of autism and developmental disorders. - New York, USA : Springer. - 0162-3257 .- 1573-3432. ; 42:2, s. 313-318
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Tidskriftsartikel (refereegranskat)abstract
- Specific biological markers for autism spectrum disorder (ASD) have not yet been established. Functional studies have shown abnormalities in the anatomo-functional connectivity of the limbic-striatal "social" brain. This study aimed to investigate regional cerebral blood flow (rCBF) at rest. Thirteen patients with ASD of normal intelligence and ten IQ-, sex- and age-matched healthy controls (HC) underwent PET/CT using [1-(11)C]butanol, a perfusion tracer. As compared to HC, ASD showed significant CBF increases in the right parahippocampal, posterior cingulate, primary visual and temporal cortex, putamen, caudatus, substantia nigra and cerebellum. No statistically significant correlation between CBF and IQ was found. The limbic, posterior associative and cerebellar cortices showed increased blood flow in ASD, confirming previous findings about the neurobiology of ASD.
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| 4. |
- Tolmachev, Vladimir, et al.
(författare)
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Radiolabelled proteins for positron emission tomography : pros and cons of labelling methods
- 2010
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Ingår i: Biochimica et Biophysica Acta. - : Elsevier BV. - 0006-3002 .- 1878-2434 .- 0304-4165. ; 1800:5, s. 487-510
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Forskningsöversikt (refereegranskat)abstract
- BACKGROUND: Dynamic biomedical research is currently yielding a wealth of information about disease-associated molecular alterations on cell surfaces and in the extracellular space. The ability to visualize and quantify these alterations in vivo could provide important diagnostic information and be used to guide individually-optimized therapy. Biotechnology can provide proteinaceous molecular probes with highly specific target recognitions. Suitably labelled, these may be used as tracers for radionuclide-based imaging of molecular disease signatures. If the labels are positron-emitting radionuclides, the superior resolution, sensitivity and quantification capability of positron emission tomography (PET) can be exploited. SCOPE OF REVIEW: This article discusses different approaches to labelling proteins with positron-emitting nuclides with suggestions made depending on the biological features of the tracers. MAJOR CONCLUSIONS: Factors such as matching biological and physical half-lives, availability of the nuclide, labelling yields, and influences of labelling on targeting properties (affinity, charge and lipophilicity, cellular processing and retention of catabolites) should be considered when selecting a labelling strategy for each proteinaceous tracer. GENERAL SIGNIFICANCE: The labelling strategy used can make all the difference between success and failure in a tracer application. This review emphasises chemical, biological and pharmacological considerations in labelling proteins with positron-emitting radionuclides.
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| 5. |
- Tolmachev, Vladimir, et al.
(författare)
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Radiolabelled receptor-tyrosine-kinase targeting drugs for patient stratification and monitoring of therapy response : prospects and pitfalls
- 2010
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Ingår i: The Lancet Oncology. - 1470-2045 .- 1474-5488. ; 11:10, s. 992-1000
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Forskningsöversikt (refereegranskat)abstract
- Transmembrane receptor tyrosine kinases (RTKs) are overexpressed in many malignancies. RTK signalling triggers cell proliferation, suppression of apoptosis, increased motility, and recruitment of neovasculature. Overexpressed RTKs are the molecular targets for an increasing number of anticancer drugs. Monoclonal antibodies block the ligands or their binding sites and prevent receptor dimerisation, thereby hindering RTK signalling. The antibody-dependent cellular cytotoxicity can boost the therapeutic effect. Small-molecule tyrosine kinase inhibitors (TKIs) hamper downstream RTK signalling by targeting the intracellular kinase domain. These drugs have significantly increased survival in several patient groups. Improved patient stratification and therapy monitoring might further enhance the efficacy of anti-RTK therapy. Radionuclide-based molecular imaging can provide methods for localising and estimating the expression of RTKs. It can potentially identify patients who have tumours that overexpress RTK and would, therefore, most likely benefit from a targeted treatment. Monitoring changes in RTK expression during therapy could help avoid overtreatment and undertreatment. Radionuclide-based methods are less invasive and less sensitive to expression heterogeneity than more conventional sampling methods. The biochemical information is also obtained in an anatomical context. The development of radiolabelled anti-RTK drugs and their analogues is the subject of intensive preclinical and translational research. In this review, we present current approaches to developing imaging probes for in-vivo RTK visualisation and discuss their advantages and disadvantages.
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| 6. |
- Wållberg, Helena, et al.
(författare)
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HER2-Positive Tumors Imaged Within 1 Hour Using a Site-Specifically C-11-Labeled Sel-Tagged Affibody Molecule
- 2012
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Ingår i: Journal of Nuclear Medicine. - Stockholm : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 53:9, s. 1446-1453
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Tidskriftsartikel (refereegranskat)abstract
- A rapid, reliable method for distinguishing tumors or metastases that overexpress human epidermal growth factor receptor 2 (HER2) from those that do not is highly desired for individualizing therapy and predicting prognoses. In vivo imaging methods are available but not yet in clinical practice; new methodologies improving speed, sensitivity, and specificity are required. Methods: A HER2-binding Affibody molecule, Z(HER2:342), was recombinantly fused with a C-terminal selenocysteine-containing tetrapeptide Sel-tag, allowing site-specific labeling with either C-11 or Ga-68, followed by biodistribution studies with small-animal PET. Dosimetry data for the 2 radiotracers were compared. Imaging of HER2-expressing human tumor xenografts was performed using the C-11-labeled Affibody molecule. Results: Both the C-11- and Ga-68-labeled tracers initially cleared rapidly from the blood, followed by a slower decrease to 4-5 percentage injected dose per gram of tissue at 1 h. Final retention in the kidneys was much lower (>5-fold) for the C-11-labeled protein, and its overall absorbed dose was considerably lower. C-11-Z(HER2:342) showed excellent tumor-targeting capability, with almost 10 percentage injected dose per gram of tissue in HER2-expressing tumors within 1 h. Specificity was demonstrated by preblocking binding sites with excess ligand, yielding significantly reduced radiotracer uptake (P = 0.002), comparable to uptake in tumors with low HER2 expression. Conclusion: To our knowledge, the Sel-tagging technique is the first that enables site-specific C-11-radiolabeling of proteins. Here we present the finding that, in a favorable combination between radionuclide half-life and in vivo pharmacokinetics of the Affibody molecules, C-11-labeled Set-tagged Z(HER2:342) can successfully be used for rapid and repeated PET studies of HER2 expression in tumors.
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