Characterization of Biomaterials with NMR

1990 ◽  
Vol 217 ◽  
Author(s):  
Leoncio Garrido ◽  
Bettina Pfleiderer ◽  
Jerome L. Ackerman ◽  
John Moore
Keyword(s):  
Chemical Shift ◽  
Mechanical Stress ◽  
Imaging Techniques ◽  
Relaxation Times ◽  
Nmr Imaging ◽  
Spin Lattice ◽  
Model Networks ◽  
Crosslink Densities

ABSTRACTSilicone based biomaterials are characterized with NMR. Bulk spin-lattice (T1) and spin-spin (T2) relaxation times are measured in polydimethylsiloxane (PDMS) model networks and various types of implants. The T2 results seem to indicate that crosslink densities of these biomaterials are lower than those of the PDMS model networks studied. 1H chemical shift NMR imaging techniques are developed to investigate the aging (e.g., migration of free polymer, rupture due to mechanical stress, etc.) of biomaterials in vivo.

scholarly journals Study of Osteocyte Behavior by High-Resolution Intravital Imaging Following Photo-Induced Ischemia

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2874
Author(s):  
Hengfeng Yuan ◽  
Wen Jiang ◽  
Yuanxin Chen ◽  
Betty Kim
Keyword(s):  
Imaging Techniques ◽  
Avascular Osteonecrosis ◽  
Functional Changes ◽  
Cellular Processes ◽  
Non Invasive ◽  
Behavioral Dynamics ◽  
Bony Anatomy ◽  
Magnetic Resonance Imaging Mri

Ischemic injuries and local hypoxia can result in osteocytes dysfunction and play a key role in the pathogenesis of avascular osteonecrosis. Conventional imaging techniques including magnetic resonance imaging (MRI) and computed tomography (CT) can reveal structural and functional changes within bony anatomy; however, characterization of osteocyte behavioral dynamics in the setting of osteonecrosis at the single cell resolution is limited. Here, we demonstrate an optical approach to study real-time osteocyte functions in vivo. Using nicotinamide adenine dinucleotide (NADH) as a biomarker for metabolic dynamics in osteocytes, we showed that NADH level within osteocytes transiently increase significantly after local ischemia through non-invasive photo-induced thrombosis of afferent arterioles followed by a steady decline. Our study presents a non-invasive optical approach to study osteocyte behavior through the modulation of local environmental conditions. Thus it provides a powerful toolkit to study cellular processes involved in bone pathologies in vivo.

scholarly journals Investigating the RAS can be a fishy business: interdisciplinary opportunities using Zebrafish

2018 ◽  
Vol 132 (23) ◽  
pp. 2469-2481 ◽  
Author(s):  
Scott Hoffmann ◽  
Linda Mullins ◽  
Charlotte Buckley ◽  
Sebastien Rider ◽  
John Mullins
Keyword(s):  
Imaging Techniques ◽  
Renin Angiotensin System ◽  
Angiotensin System ◽  
Cell Ablation ◽  
Ras Inhibition ◽  
Zebrafish Pronephros ◽  
Identification And Characterization ◽  
Structural Simplicity

The renin–angiotensin system (RAS) is highly conserved, and components of the RAS are present in all vertebrates to some degree. Although the RAS has been studied since the discovery of renin, its biological role continues to broaden with the identification and characterization of new peptides. The evolutionarily distant zebrafish is a remarkable model for studying the kidney due to its genetic tractability and accessibility for in vivo imaging. The zebrafish pronephros is an especially useful kidney model due to its structural simplicity yet complex functionality, including capacity for glomerular and tubular filtration. Both the pronephros and mesonephros contain renin-expressing perivascular cells, which respond to RAS inhibition, making the zebrafish an excellent model for studying the RAS. This review summarizes the physiological and genetic tools currently available for studying the zebrafish kidney with regards to functionality of the RAS, using novel imaging techniques such as SPIM microscopy coupled with targeted single cell ablation and synthesis of vasoactive RAS peptides.

NMR Imaging Studies of Vulcanized Butyl Rubber

1991 ◽  
Vol 64 (4) ◽  
pp. 635-640 ◽  
Author(s):  
M. R. Krejsa ◽  
J. L. Koenig
Keyword(s):  
Crosslink Density ◽  
Relaxation Times ◽  
Nmr Imaging ◽  
Thermal Gradients ◽  
Chemical Probes ◽  
Imaging Studies ◽  
Spin Lattice ◽  
T1 Relaxation ◽  
Entrapped Air ◽  
Effects Of Aging

Abstract NMR imaging is a useful technique for studying the physical and spatial microstructure of cured elastomers. Different swelling agents can be used as chemical probes to detect varying amounts of microstructural differences. Imaging can be used to detect highly cured regions due to aging, poor mixing, and thermal gradients. NMRI is thus useful to study spatial distribution of crosslinks and is sensitive to changes in this distribution of crosslinks due to thermal gradients and the effects of aging and reversion processes. It can also be used to observed entrapped air in air-aged samples. Spin-lattice T1, relaxation times for solvent in cured elastomers have been shown to be shorter than the bulk solvent T1 values, providing a new method for determining the crosslink density. NMRI results have suggested that cure reversion and postcuring processes produce similar spatial results.

Magnetic Resonance Microscopy of Chemically-Induced Liver Foci

1989 ◽  
Vol 17 (4_part_1) ◽  
pp. 613-616 ◽  
Author(s):  
G. Allan Johnson ◽  
Robert R. Maronpot
Keyword(s):  
Magnetic Resonance ◽  
Imaging Technique ◽  
Relaxation Times ◽  
Basic Research ◽  
Resonance Imaging ◽  
T2 Relaxation ◽  
Spin Lattice ◽  
Chemically Induced ◽  
Magnetic Resonance Imaging Mri

Magnetic resonance imaging (MRI) is a new imaging technique used in clinical diagnosis. This paper describes extension of the technique to basic research applications–specifically detecting and characterizing chemically-induced liver neoplasms and foci of cellular alteration. Two systems have been built that allow spatial microscopic resolution–more than 100,000 x greater than that of earlier efforts. Use of spin-lattice (T1) and spin-spin (T2) relaxation times permits detailed characterization of the tissue.

scholarly journals Watching cellular machinery in action, one molecule at a time

2016 ◽  
Vol 216 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Enrico Monachino ◽  
Lisanne M. Spenkelink ◽  
Antoine M. van Oijen
Keyword(s):  
Dynamic Behavior ◽  
Single Molecule ◽  
Protein Complexes ◽  
Imaging Techniques ◽  
Ensemble Averaging ◽  
Cellular Processes ◽  
Cellular Machinery

Single-molecule manipulation and imaging techniques have become important elements of the biologist’s toolkit to gain mechanistic insights into cellular processes. By removing ensemble averaging, single-molecule methods provide unique access to the dynamic behavior of biomolecules. Recently, the use of these approaches has expanded to the study of complex multiprotein systems and has enabled detailed characterization of the behavior of individual molecules inside living cells. In this review, we provide an overview of the various force- and fluorescence-based single-molecule methods with applications both in vitro and in vivo, highlighting these advances by describing their applications in studies on cytoskeletal motors and DNA replication. We also discuss how single-molecule approaches have increased our understanding of the dynamic behavior of complex multiprotein systems. These methods have shown that the behavior of multicomponent protein complexes is highly stochastic and less linear and deterministic than previously thought. Further development of single-molecule tools will help to elucidate the molecular dynamics of these complex systems both inside the cell and in solutions with purified components.

Centrosome dynamics in early embryos of Caenorhabditis elegans

1998 ◽  
Vol 111 (20) ◽  
pp. 3027-3033 ◽  
Author(s):  
H.H. Keating ◽  
J.G. White
Keyword(s):  
Caenorhabditis Elegans ◽  
Imaging Techniques ◽  
Early Embryo ◽  
Developmental Potential ◽  
Centrosome Separation ◽  
Early Embryos ◽  
Cell Embryo ◽  
Multiple Interactions

The early Caenorhabditis elegans embryo divides with a stereotyped pattern of cleavages to produce cells that vary in developmental potential. Differences in cleavage plane orientation arise between the anterior and posterior cells of the 2-cell embryo as a result of asymmetries in centrosome positioning. Mechanisms that position centrosomes are thought to involve interactions between microtubules and the cortex, however, these mechanisms remain poorly defined. Interestingly, in the early embryo the shape of the centrosome predicts its subsequent movement. We have used rhodamine-tubulin and live imaging techniques to study the development of asymmetries in centrosome morphology and positioning. In contrast to studies using fixed embryos, our images provide a detailed characterization of the dynamics of centrosome flattening. In addition, our observations of centrosome behavior in vivo challenge previous assumptions regarding centrosome separation by illustrating that centrosome flattening and daughter centrosome separation are distinct processes, and by revealing that nascent daughter centrosomes may become separated from the nucleus. Finally, we provide evidence that the midbody specifies a region of the cortex that directs rotational alignment of the centrosome-nucleus complex and that the process is likely to involve multiple interactions between microtubules and the cortex; the process of alignment involves oscillations and overshoots, suggesting a multiplicity of cortical sites that interact with microtubules.

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