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Righesso LAR, Terekhov M, Götz H, Ackermann M, Emrich T, Schreiber LM, Müller WEG, Jung J, Rojas JP, Al-Nawas B. Dynamic contrast-enhanced magnetic resonance imaging for monitoring neovascularization during bone regeneration-a randomized in vivo study in rabbits. Clin Oral Investig 2021; 25:5843-5854. [PMID: 33786647 PMCID: PMC8443511 DOI: 10.1007/s00784-021-03889-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 03/12/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Micro-computed tomography (μ-CT) and histology, the current gold standard methods for assessing the formation of new bone and blood vessels, are invasive and/or destructive. With that in mind, a more conservative tool, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), was tested for its accuracy and reproducibility in monitoring neovascularization during bone regeneration. Additionally, the suitability of blood perfusion as a surrogate of the efficacy of osteoplastic materials was evaluated. MATERIALS AND METHODS Sixteen rabbits were used and equally divided into four groups, according to the time of euthanasia (2, 3, 4, and 6 weeks after surgery). The animals were submitted to two 8-mm craniotomies that were filled with blood or autogenous bone. Neovascularization was assessed in vivo through DCE-MRI, and bone regeneration, ex vivo, through μ-CT and histology. RESULTS The defects could be consistently identified, and their blood perfusion measured through DCE-MRI, there being statistically significant differences within the blood clot group between 3 and 6 weeks (p = 0.029), and between the former and autogenous bone at six weeks (p = 0.017). Nonetheless, no significant correlations between DCE-MRI findings on neovascularization and μ-CT (r =-0.101, 95% CI [-0.445; 0.268]) or histology (r = 0.305, 95% CI [-0.133; 0.644]) findings on bone regeneration were observed. CONCLUSIONS These results support the hypothesis that DCE-MRI can be used to monitor neovascularization but contradict the premise that it could predict bone regeneration as well.
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Affiliation(s)
- L A R Righesso
- Clinic for Oral and Maxillofacial Surgery and Plastic Surgery, University Medical Center of the Johannes Gutenberg University Mainz, Augustusplatz 2, 55131, Mainz, Germany.
| | - M Terekhov
- Molecular and Cellular Imaging, Comprehensive Heart Failure Center, University Hospital Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - H Götz
- Cell Biology Unit, University Medical Center of the Johannes Gutenberg University Mainz, Langenbeckstrasse 1, 55131, Mainz, Germany
| | - M Ackermann
- Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University Mainz, Johann-Joachim-Becher-Weg 13, 55128, Mainz, Germany
| | - T Emrich
- Department of Radiology, University Medical Center of the Johannes Gutenberg University Mainz, Langenbeckstrasse 1, 55131, Mainz, Germany
- Medical University of South Carolina, 171 Ashley Avenue, Charleston, SC, 29425, USA
- German Center for Cardiovascular Research (DZHK), Partner-Site Rhine-Main, Potsdamer Strasse 58, 10785, Berlin, Germany
| | - L M Schreiber
- Molecular and Cellular Imaging, Comprehensive Heart Failure Center, University Hospital Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - W E G Müller
- Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, 55128, Mainz, Germany
| | - J Jung
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyung Hee University, 23, Kyung Hee Dae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - J P Rojas
- Private Practice, Av. La Dehesa, 181, Santiago, Chile
| | - B Al-Nawas
- Clinic for Oral and Maxillofacial Surgery and Plastic Surgery, University Medical Center of the Johannes Gutenberg University Mainz, Augustusplatz 2, 55131, Mainz, Germany
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Jiménez-Reina L, García-Martínez E, Rojas JP, Cañete MD, Bernal G, Cañete R. Recruiting of somatotroph cells after combined somatostatin, GHRH and growth hormone (GH) secretagogue stimulation in a study of pituitary GH reserve in prepuberal female rats. Histol Histopathol 2006; 21:1103-10. [PMID: 16835832 DOI: 10.14670/hh-21.1103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Diagnostic confirmation of growth hormone (GH) deficiency in children and adults is based on stimulation tests designed to assess the pituitary reserve by measuring the amount of GH released into the bloodstream; however, the results obtained by this means cannot provide any direct indication of the amount of GH actually produced by pituitary somatotroph cells. The present paper sought to test the hypothesis that release of GH following administration of specific stimuli does not accurately reflect the somatotroph cell response, and that the amount of GH released into the bloodstream may often be greater or smaller than the amount synthesized. GH release and changes in the proportion of somatotroph cells were charted in prepuberal female Wistar rats, following administration of several different GH stimuli: GHRH (1 microg/kg), GHRP-6 (1 microg/kg), GHRELIN (1 microg/kg) and combined GHRH-based treatments, with or without SRIH pretreatment (1 microg/kg) 90 minutes earlier. Peak serum GH values were recorded 15 minutes after administration of GHRH+GHRELIN and GHRH+GHRP-6; maximum stimulation in terms of an increased proportion of somatotroph cells occurred 15 minutes after combined adminstration of GHRH + GHRELIN. SRIH pretreatment (- 90 min) inhibited GH release, with a subsequent "escape" and lack of response to stimulation which lasted at least 30 minutes except following administration of GHRH. However, combined administration of GHRH+GHRELIN maintained stimulation of the somatotroph cell population. In conclusion, the results suggest that the enhanced GH release prompted by stimulation tests used to diagnose GH deficiency in prepuberal female rats does not fully reflect somatroph cell dynamics, and that not all the GH produced and stored by somatotroph cells is released into the bloodstream.
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Affiliation(s)
- L Jiménez-Reina
- Department of Morphological Sciences, Section of Human Anatomy, School of Medicine, Córdoba, Spain.
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