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371 results on '"Oikonen, Vesa"'

3. [11C]carfentanil PET imaging for studying the peripheral opioid system in vivo: effect of photoperiod on mu-opioid receptor availability in brown adipose tissue

Author

Sun, Lihua, Aarnio, Richard, Herre, Erika Atencio, Kärnä, Salli, Palani, Senthil, Virtanen, Helena, Liljenbäck, Heidi, Virta, Jenni, Honkaniemi, Aake, Oikonen, Vesa, Han, Chunlei, Laurila, Sanna, Bucci, Marco, Helin, Semi, Yatkin, Emrah, Nummenmaa, Lauri, Nuutila, Pirjo, Tang, Jing, and Roivainen, Anne

Published
2023
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11. Kinetic Modeling of Brain [ 18- F]FDG Positron Emission Tomography Time Activity Curves with Input Function Recovery (IR) Method.

Author

Bucci, Marco, Rebelos, Eleni, Oikonen, Vesa, Rinne, Juha, Nummenmaa, Lauri, Iozzo, Patricia, and Nuutila, Pirjo

Subjects
POSITRON emission tomography, CURVES, MODEL validation, BLOOD sampling
Abstract

Accurate positron emission tomography (PET) data quantification relies on high-quality input plasma curves, but venous blood sampling may yield poor-quality data, jeopardizing modeling outcomes. In this study, we aimed to recover sub-optimal input functions by using information from the tail (5th–100th min) of curves obtained through the frequent sampling protocol and an input recovery (IR) model trained with reference curves of optimal shape. Initially, we included 170 plasma input curves from eight published studies with clamp [18F]-fluorodeoxyglucose PET exams. Model validation involved 78 brain PET studies for which compartmental model (CM) analysis was feasible (reference (ref) + training sets). Recovered curves were compared with original curves using area under curve (AUC), max peak standardized uptake value (maxSUV). CM parameters (ref + training sets) and fractional uptake rate (FUR) (all sets) were computed. Original and recovered curves from the ref set had comparable AUC (d = 0.02, not significant (NS)), maxSUV (d = 0.05, NS) and comparable brain CM results (NS). Recovered curves from the training set were different from the original according to maxSUV (d = 3) and biologically plausible according to the max theoretical K1 (53//56). Brain CM results were different in the training set (p < 0.05 for all CM parameters and brain regions) but not in the ref set. FUR showed reductions similarly in the recovered curves of the training and test sets compared to the original curves (p < 0.05 for all regions for both sets). The IR method successfully recovered the plasma inputs of poor quality, rescuing cases otherwise excluded from the kinetic modeling results. The validation approach proved useful and can be applied to different tracers and metabolic conditions. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Quantitative Perfusion Imaging with Total-Body PET.

Author

Knuuti, Juhani, Tuisku, Jouni, Kärpijoki, Henri, Iida, Hidehiro, Maaniitty, Teemu, Latva-Rasku, Aino, Oikonen, Vesa, Nesterov, Sergey V., Teuho, Jarmo, Jaakkola, Maria K., Klén, Riku, Louhi, Heli, Saunavaara, Virva, Nuutila, Pirjo, Saraste, Antti, Rinne, Juha, and Nummenmaa, Lauri

Published
2023
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16. Lower abdominal adipose tissue cannabinoid type 1 receptor availability in young men with overweight.

Author

Pekkarinen, Laura, Kantonen, Tatu, Oikonen, Vesa, Haaparanta‐Solin, Merja, Aarnio, Richard, Dickens, Alex M., von Eyken, Annie, Latva‐Rasku, Aino, Dadson, Prince, Kirjavainen, Anna K., Rajander, Johan, Kalliokoski, Kari, Rönnemaa, Tapani, Nummenmaa, Lauri, and Nuutila, Pirjo

Subjects
CANNABINOID receptors, ABDOMINAL adipose tissue, BROWN adipose tissue, OVERWEIGHT men, POSITRON emission tomography
Abstract

Objective: Cannabinoid type 1 receptors (CB1R) modulate feeding behavior and energy homeostasis, and the CB1R tone is dysgulated in obesity. This study aimed to investigate CB1R availability in peripheral tissue and brain in young men with overweight versus lean men. Methods: Healthy males with high (HR, n = 16) or low (LR, n = 20) obesity risk were studied with fluoride 18–labeled FMPEP‐d2 positron emission tomography to quantify CB1R availability in abdominal adipose tissue, brown adipose tissue, muscle, and brain. Obesity risk was assessed by BMI, physical exercise habits, and familial obesity risk, including parental overweight, obesity, and type 2 diabetes. To assess insulin sensitivity, fluoro‐[18F]‐deoxy‐2‐D‐glucose positron emission tomography during hyperinsulinemic‐euglycemic clamp was performed. Serum endocannabinoids were analyzed. Results: CB1R availability in abdominal adipose tissue was lower in the HR than in the LR group, whereas no difference was found in other tissues. CB1R availability of abdominal adipose tissue and brain correlated positively with insulin sensitivity and negatively with unfavorable lipid profile, BMI, body adiposity, and inflammatory markers. Serum arachidonoyl glycerol concentration was associated with lower CB1R availability of the whole brain, unfavorable lipid profile, and higher serum inflammatory markers. Conclusions: The results suggest endocannabinoid dysregulation already in the preobesity state. [ABSTRACT FROM AUTHOR]

Published
2023
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20. Preclinical Evaluation of 89Zr-Desferrioxamine-Bexmarilimab, a Humanized Antibody Against Common Lymphatic Endothelial and Vascular Endothelial Receptor-1, in a Rabbit Model of Renal Fibrosis.

Author

Moisio, Olli, Virta, Jenni, Yatkin, Emrah, Liljenbäck, Heidi, Palani, Senthil, Viitanen, Riikka, Miner, Maxwell W. G., Oikonen, Vesa, Tolvanen, Tuula, Vugts, Danielle J., Taimen, Pekka, Xiang-Guo Li, Hollmén, Maija, Jalkanen, Sirpa, and Roivainen, Anne

Published
2023
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21. [18F]Fluoride uptake in various bone types and soft tissues in rat.

Author

Savisto, Nina, Grönroos, Tove J., Oikonen, Vesa, Rajander, Johan, Löyttyniemi, Eliisa, Bergman, Jörgen, Forsback, Sarita, Solin, Olof, and Haaparanta-Solin, Merja

Subjects
SPRAGUE Dawley rats, ILIUM, LUMBAR vertebrae, LUNGS, COMPACT bone, CANCELLOUS bone, COMPUTED tomography
Abstract

Background: In the development of new 18F-labelled tracers, it is important to assess the amount of released [18F]fluoride taken up in the bones of experimental animals because all 18F-labelled PET-tracers are prone, to lesser or higher degree, to undergo defluorination, with subsequent release of [18F]fluoride during scanning. However, the pharmacokinetics of [18F]fluoride in bones and other organs of healthy rats have not been well documented in a comprehensive manner. We aimed to study pharmacokinetics of [18F]NaF in rats in order to increase our understanding of the biodistribution of [18F]fluoride originating from defluorination of 18F-labelled tracers. We studied [18F]fluoride uptake in Sprague Dawley rat bones, including the epiphyseal parts of the tibia and radius, the mandible, ilium, lumbar vertebrae, costochondral joints, tibia, radius, and ribs, with 60-min in vivo PET/CT imaging. Kinetic parameters, K1, Ki, Ki/K1, and k3 were calculated with a three-compartment model. In addition, separate groups of male and female rats were studied with ex vivo bone and soft tissue harvesting and gamma counting over a 6-h period. Results: [18F]fluoride perfusion and uptake varied among the different bones. [18F]fluoride uptake was higher in trabecular bones, due to high perfusion and osteoblastic activity, compared to cortical bones. In soft tissues, the organ-to-blood uptake ratios increased over time in the eyes, lungs, brain, testes, and ovaries during the 6 h study period. Conclusion: Understanding the pharmacokinetics of [18F]fluoride in various bones and soft tissues is highly useful for assessing 18F-labelled radiotracers that release [18F]fluoride. [ABSTRACT FROM AUTHOR]

Published
2023
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22. Positron emission tomography imaging of the 18-kDa translocator protein (TSPO) with [18F]FEMPA in Alzheimer’s disease patients and control subjects

Author

Varrone, Andrea, Oikonen, Vesa, Forsberg, Anton, Joutsa, Juho, Takano, Akihiro, Solin, Olof, Haaparanta-Solin, Merja, Nag, Sangram, Nakao, Ryuji, Al-Tawil, Nabil, Wells, Lisa A., Rabiner, Eugenii A., Valencia, Ray, Schultze-Mosgau, Marcus, Thiele, Andrea, Vollmer, Sonja, Dyrks, Thomas, Lehmann, Lutz, Heinrich, Tobias, Hoffmann, Anja, Nordberg, Agneta, Halldin, Christer, and Rinne, Juha O.

Published
2015
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25. 11C-ORM-13070, a novel PET ligand for brain α2C-adrenoceptors: radiometabolism, plasma pharmacokinetics, whole-body distribution and radiation dosimetry in healthy men

Author

Luoto, Pauliina, Suilamo, Sami, Oikonen, Vesa, Arponen, Eveliina, Helin, Semi, Herttuainen, Jukka, Hietamäki, Johanna, Holopainen, Aila, Kailajärvi, Marita, Peltonen, Juha M., Rouru, Juha, Sallinen, Jukka, Scheinin, Mika, Virta, Jere, Virtanen, Kirsi, Volanen, Iina, Roivainen, Anne, and Rinne, Juha O.

Published
2014
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27. Quantification of the purinergic P2X7 receptor with [ 11 C]SMW139 improves through correction for brain-penetrating radiometabolites.

Author

Brumberg, Joachim, Aarnio, Richard, Forsberg, Anton, Marjamäki, Päivi, Kerstens, Vera, Moein, Mohammad M, Nag, Sangram, Wahlroos, Saara, Kassiou, Michael, Windhorst, Albert D, Halldin, Christer, Haaparanta-Solin, Merja, Fazio, Patrik, Oikonen, Vesa, Rinne, Juha O, and Varrone, Andrea

Abstract

The membrane-based purinergic 7 receptor (P2X7R) is expressed on activated microglia and the target of the radioligand [11C]SMW139 for in vivo assessment of neuroinflammation. This study investigated the contribution of radiolabelled metabolites which potentially affect its quantification. Ex vivo high-performance liquid chromatography with a radio detector (radioHPLC) was used to evaluate the parent and radiometabolite fractions of [11C]SMW139 in the brain and plasma of eleven mice. Twelve healthy humans underwent 90-min [11C]SMW139 brain PET with arterial blood sampling and radiometabolite analysis. The volume of distribution was estimated by using one- and two- tissue compartment (TCM) modeling with single (V T) and dual (V Tp) input functions. RadioHPLC showed three major groups of radiometabolite peaks with increasing concentrations in the plasma of all mice and humans. Two radiometabolite peaks were also visible in mice brain homogenates and therefore considered for dual input modeling in humans. 2TCM with single input function provided V T estimates with a wide range (0.10–10.74) and high coefficient of variation (COV: 159.9%), whereas dual input function model showed a narrow range of V Tp estimates (0.04–0.24; COV: 33.3%). In conclusion, compartment modeling with correction for brain-penetrant radiometabolites improves the in vivo quantification of [11C]SMW139 binding to P2X7R in the human brain. [ABSTRACT FROM AUTHOR]

Published
2023
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28. [11C]carfentanil PET imaging for studying the peripheral opioid system in vivo: effect of photoperiod on mu-opioid receptor availability in brown adipose tissue.

Author

Sun, Lihua, Aarnio, Richard, Herre, Erika Atencio, Kärnä, Salli, Palani, Senthil, Virtanen, Helena, Liljenbäck, Heidi, Virta, Jenni, Honkaniemi, Aake, Oikonen, Vesa, Han, Chunlei, Laurila, Sanna, Bucci, Marco, Helin, Semi, Yatkin, Emrah, Nummenmaa, Lauri, Nuutila, Pirjo, Tang, Jing, and Roivainen, Anne

Subjects
POSITRON emission tomography, ADIPOSE tissues, BODY temperature regulation, IMMUNOFLUORESCENCE, BODY mass index
Abstract

Purpose: Photoperiod determines the metabolic activity of brown adipose tissue (BAT) and affects the food intake and body mass of mammals. Sympathetic innervation of the BAT controls thermogenesis and facilitates physiological adaption to seasonal changes, but the exact mechanism remains elusive. Previous studies have shown that central opioid signaling regulates BAT thermogenesis, and that the expression of the brain mu-opioid receptor (MOR) varies seasonally. Therefore, it is important to know whether MOR expression in BAT shows seasonal variation. Methods: We determined the effect of photoperiod on BAT MOR availability using [11C]carfentanil positron emission tomography (PET). Adult rats (n = 9) were repeatedly imaged under various photoperiods in order to simulate seasonal changes. Results: Long photoperiod was associated with low MOR expression in BAT (β = − 0.04, 95% confidence interval: − 0.07, − 0.01), but not in muscles. We confirmed the expression of MOR in BAT and muscle using immunofluorescence staining. Conclusion: Photoperiod affects MOR availability in BAT. Sympathetic innervation of BAT may influence thermogenesis via the peripheral MOR system. The present study supports the utility of [11C]carfentanil PET to study the peripheral MOR system. [ABSTRACT FROM AUTHOR]

Published
2023
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38. Regulation of human skeletal muscle perfusion and its heterogeneity during exercise in moderate hypoxia

Author

Heinonen, Ilkka H., Kemppainen, Jukka, Kaskinoro, Kimmo, Peltonen, Juha E., Borra, Ronald, Lindroos, Markus, Oikonen, Vesa, Nuutila, Pirjo, Knuuti, Juhani, Boushel, Robert, and Kalliokoski, Kari K.

Subjects
Muscles -- Properties, Perfusion (Physiology) -- Research, Hypoxia -- Development and progression, PET imaging -- Methods, Exercise -- Physiological aspects, Exercise -- Research, Biological sciences
Abstract

Although many effects of both acute and chronic hypoxia on the circulation are well characterized, the distribution and regulation of blood flow (BF) heterogeneity in skeletal muscle during systemic hypoxia is not well understood in humans. We measured muscle BF within the thigh muscles of nine healthy young men using positron emission tomography during one-leg dynamic knee extension exercise in normoxia and moderate physiological systemic hypoxia (14% [O.sub.2] corresponding to ~3,400 m of altitude) without and with local adenosine receptor inhibition with femoral artery infusion of aminophylline. Systemic hypoxia reduced oxygen extraction of the limb but increased muscle BF, and this flow increment was confined solely to the exercising quadriceps femoris muscle. Exercising muscle BF heterogeneity was reduced from rest (P = 0.055) but was not affected by hypoxia. Adenosine receptor inhibition had no effect on capillary BF during exercise in either normoxia or hypoxia. Finally, one-leg exercise increased muscle BF heterogeneity both in the resting posterior hamstring part of the exercising leg and in the resting contralateral leg, whereas mean BF was unchanged. In conclusion, the results show that increased BF during one-leg exercise in moderate hypoxia is confined only to the contracting muscles, and the working muscle hyperemia appears not to be directly mediated by adenosine. Increased flow heterogeneity in noncontracting muscles likely reflects sympathetic nervous constraints to curtail BF increments in areas other than working skeletal muscles, but this effect is not potentiated in moderate systemic hypoxia during small muscle mass exercise. positron emission tomography; exercise; hypoxia doi: 10.1152/ajpregu.00056.2010.

Published
2010

39. Pancreatic Metabolism, Blood Flow, and β-Cell Function in Obese Humans

Author

Honka, Henri, Hannukainen, Jarna C., Tarkia, Miikka, Karlsson, Henry, Saunavaara, Virva, Salminen, Paulina, Soinio, Minna, Mikkola, Kirsi, Kudomi, Nobu, Oikonen, Vesa, Haaparanta-Solin, Merja, Roivainen, Anne, Parkkola, Riitta, Iozzo, Patricia, and Nuutila, Pirjo

Published
2014

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