scholarly journals Cine flow measurements using phase contrast with undersampled projections: In vitro validation and preliminary results in vivo

2006 ◽  
Vol 24 (4) ◽  
pp. 945-951 ◽  
Author(s):  
Andrew L. Wentland ◽  
Frank R. Korosec ◽  
Karl K. Vigen ◽  
Oliver Wieben ◽  
Jason P. Fine ◽  
...  
Keyword(s):  
Phase Contrast ◽  
Flow Measurements ◽  
Preliminary Results

PERFUSION OF OVARIES IN VITRO AND IN VIVO

1972 ◽  
Vol 68 (2_Supplb) ◽  
pp. S285-S309 ◽  
Author(s):  
Kurt Ahrén ◽  
Per Olof Janson ◽  
Gunnar Selstam
Keyword(s):  
Perfusion System ◽  
Perfusion Technique ◽  
Preliminary Results ◽  
Advantages And Disadvantages

ABSTRACT This paper discusses in vivo and in vitro ovarian perfusion systems described so far in the literature. The interest is not focussed primarily on the results of these studies but rather on the advantages and disadvantages of the techniques and methods used. Another part of the paper summarizes the points which are most important, in our opinion, to take into consideration when developing an in vitro perfusion technique of the ovary. The last part of the paper gives a description of and some preliminary results from an in vitro perfusion system of the rabbit ovary which is under development in this laboratory.

scholarly journals Plant-Derived Extracellular Vesicles: Current Findings,Challenges, and Future Applications

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 411
Author(s):  
Nader Kameli ◽  
Anya Dragojlovic-Kerkache ◽  
Paul Savelkoul ◽  
Frank R. Stassen
Keyword(s):  
Human Health ◽  
Extracellular Vesicles ◽  
Preliminary Results ◽  
In Vivo Experiments ◽  
Health And Disease ◽  
Conducting Research ◽  
Protocol Standardization ◽  
Insight Into

In recent years, plant-derived extracellular vesicles (PDEVs) have gained the interest of many experts in fields such as microbiology and immunology, and research in this field has exponentially increased. These nano-sized particles have provided researchers with a number of interesting findings, making their application in human health and disease very promising. Both in vitro and in vivo experiments have shown that PDEVs can exhibit a multitude of effects, suggesting that these vesicles may have many potential future applications, including therapeutics and nano-delivery of compounds. While the preliminary results are promising, there are still some challenges to face, such as a lack of protocol standardization, as well as knowledge gaps that need to be filled. This review aims to discuss various aspects of PDEV knowledge, including their preliminary findings, challenges, and future uses, giving insight into the complexity of conducting research in this field.

scholarly journals In vitro evaluation of cerebrospinal fluid velocity measurement in type I Chiari malformation: repeatability, reproducibility, and agreement using 2D phase contrast and 4D flow MRI

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Gwendolyn Williams ◽  
Suraj Thyagaraj ◽  
Audrey Fu ◽  
John Oshinski ◽  
Daniel Giese ◽  
...  
Keyword(s):  
Chiari Malformation ◽  
Phase Contrast ◽  
Patient Specific ◽  
Type I ◽  
4D Flow ◽  
Csf Dynamics ◽  
Flow Measurements ◽  
Repeatability And Reproducibility ◽  
Flow Techniques

Abstract Background Phase contrast magnetic resonance imaging, PC MRI, is a valuable tool allowing for non-invasive quantification of CSF dynamics, but has lacked adoption in clinical practice for Chiari malformation diagnostics. To improve these diagnostic practices, a better understanding of PC MRI based measurement agreement, repeatability, and reproducibility of CSF dynamics is needed. Methods An anatomically realistic in vitro subject specific model of a Chiari malformation patient was scanned three times at five different scanning centers using 2D PC MRI and 4D Flow techniques to quantify intra-scanner repeatability, inter-scanner reproducibility, and agreement between imaging modalities. Peak systolic CSF velocities were measured at nine axial planes using 2D PC MRI, which were then compared to 4D Flow peak systolic velocity measurements extracted at those exact axial positions along the model. Results Comparison of measurement results showed good overall agreement of CSF velocity detection between 2D PC MRI and 4D Flow (p = 0.86), fair intra-scanner repeatability (confidence intervals ± 1.5 cm/s), and poor inter-scanner reproducibility. On average, 4D Flow measurements had a larger variability than 2D PC MRI measurements (standard deviations 1.83 and 1.04 cm/s, respectively). Conclusion Agreement, repeatability, and reproducibility of 2D PC MRI and 4D Flow detection of peak CSF velocities was quantified using a patient-specific in vitro model of Chiari malformation. In combination, the greatest factor leading to measurement inconsistency was determined to be a lack of reproducibility between different MRI centers. Overall, these findings may help lead to better understanding for application of 2D PC MRI and 4D Flow techniques as diagnostic tools for CSF dynamics quantification in Chiari malformation and related diseases.

Hemodynamics in the abdominal aorta: a comparison of in vitro and in vivo measurements

1994 ◽  
Vol 76 (4) ◽  
pp. 1520-1527 ◽  
Author(s):  
J. E. Moore ◽  
S. E. Maier ◽  
D. N. Ku ◽  
P. Boesiger
Keyword(s):  
Abdominal Aorta ◽  
Velocity Profiles ◽  
Flow Reversal ◽  
Infrarenal Aorta ◽  
Complex Flow ◽  
Flow Measurements ◽  
In Vivo Measurements ◽  
Made In

In vivo measurements of blood velocity profiles are difficult to obtain and interpret, since the parameters that govern the normally highly complex flow situation may not be fully quantified or understood at the time of measurement. In vitro flow models have been used often to better understand vascular hemodynamics. The assumptions made in the design of these models limit the applicability of the results. In this study, in vitro flow measurements made in a carefully designed model of the abdominal aorta were compared with in vivo measurements obtained with magnetic resonance imaging. In the suprarenal aorta, the velocity profiles were mostly forward and axisymmetric in both the in vitro and in vivo cases. In the infrarenal aorta, there was extensive flow reversal noted near the posterior wall in both cases. In the aortic bifurcation, two peaks of flow reversal were noted near the lateral posterior walls, and M-shaped velocity profiles were observed in late diastole. The in vitro and in vivo measurements exhibited good qualitative agreement. The in vitro model was accurate in modeling the in vivo hemodynamics of the abdominal aorta. The complex phenomena observed in vivo were explained on the basis of knowledge gained from the in vitro study.

scholarly journals In vitro validation of phase-contrast flow measurements at 3 T in comparison to 1.5 T: Precision, accuracy, and signal-to-noise ratios

2005 ◽  
Vol 21 (5) ◽  
pp. 604-610 ◽  
Author(s):  
Joachim Lotz ◽  
Rolf Döker ◽  
Ralph Noeske ◽  
Meike Schüttert ◽  
Roland Felix ◽  
...  
Keyword(s):  
Phase Contrast ◽  
Signal To Noise ◽  
Flow Measurements ◽  
Contrast Flow ◽  
Phase Contrast Flow

scholarly journals Zero filled partial fourier phase contrast MR imaging: In vitro and in vivo assessment

2005 ◽  
Vol 23 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Gilberto Szarf ◽  
Yoav Dori ◽  
Dan Rettmann ◽  
Aylin Tekes ◽  
Khurram Nasir ◽  
...  
Keyword(s):  
Mr Imaging ◽  
Phase Contrast ◽  
In Vivo Assessment

scholarly journals Ghrelin in rat pancreatic islets decreases islet blood flow

2019 ◽  
Vol 317 (1) ◽  
pp. E139-E146 ◽  
Author(s):  
Carl Johan Drott ◽  
Petra Franzén ◽  
Per-Ola Carlsson
Keyword(s):  
Blood Flow ◽  
Insulin Response ◽  
Physiological Mechanism ◽  
Growth Hormone Secretagogue Receptor ◽  
Flow Measurements ◽  
Growth Hormone Secretagogue ◽  
Islet Blood Flow ◽  
Fasted Rats

The peptide ghrelin is mainly produced in some of the epithelial cells in the stomach, but also, during starvation, by the ε-cells in the endocrine pancreas. Ghrelin, as an endogenous ligand for the growth hormone secretagogue receptor (GHS-R1α), exerts a variety of metabolic functions including stimulation of appetite and weight gain. Its complete role is not yet fully understood, including whether it has any vascular functions. The present study evaluated if ghrelin affects pancreatic and islet blood flow. Ghrelin and the GHS-R1α receptor antagonist GHRP-6 were injected intravenously in rats followed by blood flow measurements using a microsphere technique. Ghrelin decreased, while GHRP-6 in fasted, but not fed, rats selectively increased islet blood flow fourfold. GHS-R1α was identified not only on glucagon-producing cells but also seemed to be present in the islet arterioles. GHRP-6 in fasted rats, only, also improved the peak insulin response to glucose in vivo, thereby substantially blunting the hyperglycemia. GHRP-6 doubled glucose-stimulated insulin release in vitro of both islets obtained from fed and fasted rats. Our results indicate a novel role for endogenous ghrelin acting directly or indirectly as a local vasoconstrictor in the islets during fasting, thereby restricting the insulin response to hyperglycemia. This is to the best of our knowledge the first report that shows this physiological mechanism to restrict insulin delivery from the islets by acting on the vasculature; a mode of action that can be envisaged to complement the previously well-described mechanisms of ghrelin acting directly on the islet endocrine cells.

66 DEVELOPMENT OF IN VITRO-PRODUCED CAT EMBRYOS AFTER VITRIFICATION AND NONSURGICAL EMBRYO TRANSFER: PRELIMINARY RESULTS

2009 ◽  
Vol 21 (1) ◽  
pp. 133
Author(s):  
E. Iacono ◽  
B. Merlo ◽  
M. Regazzini ◽  
D. Zambelli
Keyword(s):  
Ethylene Glycol ◽  
Embryo Transfer ◽  
Domestic Cat ◽  
Embryo Survival ◽  
Abdominal Ultrasonography ◽  
Preliminary Results ◽  
Pregnancy Status ◽  
Viable Embryo

There are no refereed reports on vitrification of domestic cat embryos derived from in vitro-matured oocytes and transferred using a nonsurgical embryo transfer technique. The aim of this study was to verify the effects of vitrification on the in vitro and in vivo developmental ability of in vitro-produced (IVP) cat blastocysts. Oocytes recovered from minced ovaries were matured, fertilized, and cultured in vitro as previously reported (Merlo B et al. 2005 Theriogenology 63, 2032–2039). On Day 7 of in vitro culture (IVC), blastocysts were selected and vitrified in straws (Cristal ET 0.25 mL, 133 mm, IMV-Technologies, Paillette Crista, France). For vitrification (modified from Campos-Chillòn LF et al. 2006 Theriogenology 65, 1200–1214), the embryos were transferred in 1 mL of V1 [ethylene glycol 3.5 m in HEPES synthetic oviductal fluid (HSOF)] for 3 min, and then in 10 μL of V2 (ethylene glycol 7 m, galactose 0.5 m, Ficoll 70 18% in HSOF) for 20 s. Finally, the embryos were loaded in straws preloaded with 190 μL of dilution solution (galactose 0.5 m in HSOF). Straws were heat sealed and immediately plunged into liquid nitrogen. Vitrified embryos were warmed in air for 10 s, and then in a waterbath at 37°C for 30 s. For developmental ability and in vitro evaluation, 27 embryos were warmed and immediately examined: 25 re-expanded, 2 did not re-expand, and 1 had damaged zona pellucida. Re-expanded embryos were cultured in SOF plus amino acids, 16 mg mL–1 BSA, and 5% fetal bovine serum at 38.5°C in 5% O2, 5% CO2, 90% N2. After 24 h of IVC, only 4 blastocysts were expanded, and after 48 h, embryos were clearly degenerated or shrunk. in vivo developmental ability was tested by nonsurgical embryo transfer of 8 vitrified-warmed embryos and 6 IVP fresh embryos into 2 natural estrus queens, injected with 200 IU of hCG i.m. (Day 0) for induction of ovulation. Ovulation was confirmed by plasmatic progesterone assay on Day 5. Nonsurgical embryo transfer was made on Day 8 using the catheter proposed by Zambelli et al. 2001 for transcervical insemination in the cat. The catheter was connected to a 1-mL syringe and loaded with the embryos. Then, it was inserted in the vagina and transrectally guided into the uterus, where the embryos were deposited. To assess pregnancy status, abdominal ultrasonography was done on recipients on Day 13, 25, and 40. On Day 13, an embryonic vesicle was observed in both queens, although a smaller diameter than expected was detected in the recipient of the vitrified embryos. On Day 25, a viable embryo was detected only in the recipient of fresh IVP embryos. On Day 40, the gestational chamber was still present but no sign of a viable embryo was detected. Further studies are in progress to improve the nominal incidence of pregnancy and frequency of embryo survival after vitrification. Nevertheless, the preliminary results obtained using an AI catheter for nonsurgical embryo transfer are encouraging, and the improvement of the technique could make it reliable in the cat. Supported by Animal Stem Cells Laboratory, Regione Emilia Romagna, PRRIITT Project Number M-404AIWTSV.

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