Name: analysis of &#946;-amyloid-induced abnormalities on fibrin clot structure by spectroscopy and scanning electron microscopy
Uploaded: 2018-11-30T14:30:00
Description: Watch this Scientific Journal Video about Analysis of ÃŽÂ²-Amyloid-induced Abnormalities on Fibrin Clot Structure by Spectroscopy and Scanning Electron Microscopy at JoVE.com

Authors thank Masanori Kawasaki, Kazuyoshi Aso, and Michael Foley from Tri-Institutional Therapeutics Discovery Institute (TDI), New York for synthesis of A&#946;-fibrinogen interaction inhibitors and their valuable suggestions. Authors also thank members of the Strickland lab for helpful discussion. This work was supported by NIH grant NS104386, the Alzheimer&#39;s Drug Discovery Foundation, and Robertson Therapeutic Development Fund for H.A., NIH grant NS50537, the Tri-Institutional Therapeutics Discovery Institute, Alzheimer&#39;s Drug Discovery Foundation, Rudin Family Foundation, and John A. Herrmann for S.S.

1. Preparation of A&#946;42 and Fibrinogen for Analysis
<ol>
	<li>Prepare monomeric A&#946;42 from lyophilized powder
	<ol>
		<li>Warm A&#946;42 powder to room temperature and spin down at 1,500 x g for 30 s.</li>
		<li>Add 100 &#181;L of ice-cold hexafluoroisopropanol (HFIP) per 0.5 mg of A&#946;42 powder and incubate for 30 min on ice. 
		CAUTION: Use care when handling HFIP and perform all steps in a chemical hood.</li>
		<li>Prepare 20 &#181;L aliquots and let the films air dry in a chemical hood for 2-3 h. Fi...

<ol>
	<li>Selkoe, D. J., Schenk, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alzheimer's+disease:+molecular+understanding+predicts+amyloid-based+therapeutics.">Alzheimer's disease: molecular understanding predicts amyloid-based therapeutics.</a> Annual Review of Pharmacology and Toxicology. 43, 545-584 (2003).</li><li>Kurz, A., Perneczky, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amyloid+clearance+as+a+treatment+target+against+Alzheimer's+disease.">Amyloid clearance as a treatment target against Alzheimer's disease.</a> Journal of Alzheimer's Disease. 24, 61-73 (2011).</li><li>Benilova, I., Karran, E., De Strooper, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+toxic+Abeta+oligomer+and+Alzheimer's+disease:+an+emperor+in+need+of+clothes.">The toxic Abeta oligomer and Alzheimer's disease: an emperor in need of clothes.</a> Nature Neuroscience. 15 (3), 349-357 (2012).</li><li>Karran, E., Hardy, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+critique+of+the+drug+discovery+and+phase+3+clinical+programs+targeting+the+amyloid+hypothesis+for+Alzheimer+disease.">A critique of the drug discovery and phase 3 clinical programs targeting the amyloid hypothesis for Alzheimer disease.</a> Annals of Neurology. 76 (2), 185-205 (2014).</li><li>Yoshikawa, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterogeneity+of+cerebral+blood+flow+in+Alzheimer+disease+and+vascular+dementia.">Heterogeneity of cerebral blood flow in Alzheimer disease and vascular dementia.</a> AJNR, American Journal of Neuroradiology. 24 (7), 1341-1347 (2003).</li><li>Strickland, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood+will+out:+vascular+contributions+to+Alzheimer's+disease.">Blood will out: vascular contributions to Alzheimer's disease.</a> The Journal of Clinical Investigation. 128 (2), 556-563 (2018).</li><li>Ahn, H. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alzheimer's+disease+peptide+beta-amyloid+interacts+with+fibrinogen+and+induces+its+oligomerization.">Alzheimer's disease peptide beta-amyloid interacts with fibrinogen and induces its oligomerization.</a> Proceedings of the National Academy of Sciences of the United States of America. 107 (50), 21812-21817 (2010).</li><li>Zamolodchikov, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biochemical+and+structural+analysis+of+the+interaction+between+beta-amyloid+and+fibrinogen.">Biochemical and structural analysis of the interaction between beta-amyloid and fibrinogen.</a> Blood. 128 (8), 1144-1151 (2016).</li><li>Cortes-Canteli, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibrinogen+and+beta-amyloid+association+alters+thrombosis+and+fibrinolysis:+a+possible+contributing+factor+to+Alzheimer's+disease.">Fibrinogen and beta-amyloid association alters thrombosis and fibrinolysis: a possible contributing factor to Alzheimer's disease.</a> Neuron. 66 (5), 695-709 (2010).</li><li>Cortes-Canteli, M., Mattei, L., Richards, A. T., Norris, E. H., Strickland, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibrin+deposited+in+the+Alzheimer's+disease+brain+promotes+neuronal+degeneration.">Fibrin deposited in the Alzheimer's disease brain promotes neuronal degeneration.</a> Neurobiology of Aging. 36 (2), 608-617 (2015).</li><li>Liao, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteomic+characterization+of+postmortem+amyloid+plaques+isolated+by+laser+capture+microdissection.">Proteomic characterization of postmortem amyloid plaques isolated by laser capture microdissection.</a> The Journal of Biological Chemistry. 279 (35), 37061-37068 (2004).</li><li>Zamolodchikov, D., Strickland, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Abeta+delays+fibrin+clot+lysis+by+altering+fibrin+structure+and+attenuating+plasminogen+binding+to+fibrin.">Abeta delays fibrin clot lysis by altering fibrin structure and attenuating plasminogen binding to fibrin.</a> Blood. 119 (14), 3342-3351 (2012).</li><li>Ahn, H. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+Abeta-fibrinogen+interaction+inhibitor+rescues+altered+thrombosis+and+cognitive+decline+in+Alzheimer's+disease+mice.">A novel Abeta-fibrinogen interaction inhibitor rescues altered thrombosis and cognitive decline in Alzheimer's disease mice.</a> The Journal of Experimental Medicine. 211 (6), 1049-1062 (2014).</li><li>Singh, P. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aminopyrimidine+Class+Aggregation+Inhibitor+Effectively+Blocks+Abeta-Fibrinogen+Interaction+and+Abeta-Induced+Contact+System+Activation.">Aminopyrimidine Class Aggregation Inhibitor Effectively Blocks Abeta-Fibrinogen Interaction and Abeta-Induced Contact System Activation.</a> Biochemistry. 57 (8), 1399-1409 (2018).</li><li>Pretorius, E., Mbotwe, S., Bester, J., Robinson, C. J., Kell, D. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+induction+of+anomalous+and+amyloidogenic+blood+clotting+by+molecular+amplification+of+highly+substoichiometric+levels+of+bacterial+lipopolysaccharide.">Acute induction of anomalous and amyloidogenic blood clotting by molecular amplification of highly substoichiometric levels of bacterial lipopolysaccharide.</a> Journal of the Royal Society Interface. 13 (122), (2016).</li><li>Veklich, Y., Francis, C. W., White, J., Weisel, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+studies+of+fibrinolysis+by+electron+microscopy.">Structural studies of fibrinolysis by electron microscopy.</a> Blood. 92 (12), 4721-4729 (1998).</li><li>Weisel, J. W., Nagaswami, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computer+modeling+of+fibrin+polymerization+kinetics+correlated+with+electron+microscope+and+turbidity+observations:+clot+structure+and+assembly+are+kinetically+controlled.">Computer modeling of fibrin polymerization kinetics correlated with electron microscope and turbidity observations: clot structure and assembly are kinetically controlled.</a> Biophysical Journal. 63 (1), 111-128 (1992).</li><li>Chernysh, I. N., Nagaswami, C., Purohit, P. K., Weisel, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibrin+clots+are+equilibrium+polymers+that+can+be+remodeled+without+proteolytic+digestion.">Fibrin clots are equilibrium polymers that can be remodeled without proteolytic digestion.</a> Scientific Reports. 2, 879 (2012).</li><li>Klunk, W. E., Jacob, R. F., Mason, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantifying+amyloid+beta-peptide+(Abeta)+aggregation+using+the+Congo+red-Abeta+(CR-abeta)+spectrophotometric+assay.">Quantifying amyloid beta-peptide (Abeta) aggregation using the Congo red-Abeta (CR-abeta) spectrophotometric assay.</a> Analytical Biochemistry. 266 (1), 66-76 (1999).</li><li>Zhao, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+amyloid+formation+by+turbidity+assay-seeing+through+the+cloud.">Measurement of amyloid formation by turbidity assay-seeing through the cloud.</a> Biophysical Reviews. 8 (4), 445-471 (2016).</li><li>Bester, J., Soma, P., Kell, D. B., Pretorius, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Viscoelastic+and+ultrastructural+characteristics+of+whole+blood+and+plasma+in+Alzheimer-type+dementia,+and+the+possible+role+of+bacterial+lipopolysaccharides+(LPS).">Viscoelastic and ultrastructural characteristics of whole blood and plasma in Alzheimer-type dementia, and the possible role of bacterial lipopolysaccharides (LPS).</a> Oncotarget. 6 (34), 35284-35303 (2015).</li><li>Pretorius, E., Page, M. J., Mbotwe, S., Kell, D. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lipopolysaccharide-binding+protein+(LBP)+can+reverse+the+amyloid+state+of+fibrin+seen+or+induced+in+Parkinson's+disease.">Lipopolysaccharide-binding protein (LBP) can reverse the amyloid state of fibrin seen or induced in Parkinson's disease.</a> PLoS One. 13 (3), e0192121 (2018).</li><li>Kell, D. B., Pretorius, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteins+behaving+badly.+Substoichiometric+molecular+control+and+amplification+of+the+initiation+and+nature+of+amyloid+fibril+formation:+lessons+from+and+for+blood+clotting.">Proteins behaving badly. Substoichiometric molecular control and amplification of the initiation and nature of amyloid fibril formation: lessons from and for blood clotting.</a> Progress in Biophysics and Molecular Biology. 123, 16-41 (2017).</li><li>Wolberg, A. S., Campbell, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thrombin+generation,+fibrin+clot+formation+and+hemostasis.">Thrombin generation, fibrin clot formation and hemostasis.</a> Transfusion and Apheresis Science. 38 (1), 15-23 (2008).</li><li>Soon, A. S., Lee, C. S., Barker, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+fibrin+matrix+properties+via+knob:hole+affinity+interactions+using+peptide-PEG+conjugates.">Modulation of fibrin matrix properties via knob:hole affinity interactions using peptide-PEG conjugates.</a> Biomaterials. 32 (19), 4406-4414 (2011).</li></ol>

The methods described here provide a reproducible and rapid means of assessing fibrin clot formation in vitro. Furthermore, the simplicity of the system makes the interpretation of how A&#946; affects the fibrin clot formation and structure relatively straight-forward. In this lab&#39;s previous publication, it was shown that these assays can be used to test compounds for their ability to inhibit the A&#946;-fibrinogen interaction13,14. Using these two a...

Alzheimer's disease (AD), a neurodegenerative disease leading to cognitive decline in elderly patients, predominately arises from abnormal beta-amyloid (A&#946;) expression, aggregation and impaired clearance resulting in neurotoxicity1,2. Despite the well-characterized association between A&#946; aggregates and AD3, the precise mechanisms underlying the disease pathology are not well understood4. Increasing evidence suggests that neurovascular deficits play a role in the progression and severity of AD5, as A&#946; directly interacts with the components of the circulatory system6. A&#946; has a high-affinity interaction with fibrinogen7,8, which also localizes to A&#946; deposits in both AD patients and mouse models9,10,11. Furthermore, the A&#946;-fibrinogen interaction induces abnormal fibrin-clot formation and structure, as well as resistance to fibrinolysis9,12. One therapeutic possibility in treating AD, is alleviating circulatory deficits by inhibiting the interaction between A&#946; and fibrinogen13,14. We, therefore, identified several small compounds inhibiting the A&#946;-fibrinogen interaction using high throughput screening and medicinal chemistry approaches13,14. To test the efficacy of A&#946;-fibrinogen interaction inhibitors, we optimized two methods for the analysis of in vitro fibrin clot formation: clot turbidity assay and scanning electron microscopy (SEM)14.
Clot turbidity assay is a straight-forward and rapid method for monitoring fibrin clot formation using UV-visible spectroscopy. As the fibrin clot forms, light is increasingly scattered and the turbidity of the solution increases. Conversely, when A&#946; is present, the structure of the fibrin clot is altered, and the turbidity of the mixture is reduced (Figure 1). The effect of inhibitory compounds can be assessed for the potential to restore clot turbidity from A&#946;-induced abnormalities. While the turbidity assay allows for rapid analysis of multiple conditions, it provides limited information on the clot shape and structure. SEM, in which the topography of solid objects is revealed by electron probe, allows for the analysis of the 3D architecture of the clot15,16,17,18 and the assessment of how the presence of A&#946; and/or inhibitory compounds alters that structure9,14. Both spectrometry and SEM are classical laboratory techniques that have been used for various purposes, for example, spectrophotometry is used for monitoring amyloid aggregation19,20. Similarly, SEM is also used to analyze fibrin clot formed from the plasma of Alzheimer's, Parkinson's and thromboembolic stroke patients21,22,23. The protocols presented here are optimized for assessing fibrin-clot formation in a reproducible and rapid manner. 
The following protocol provides the instructions for the preparation of an in vitro fibrin-clot both with and without A&#946;. It also details the methods to analyze the effect of A&#946; on fibrin clot formation and structure. The effectiveness of these two methods for measuring the inhibition of the A&#946;-fibrinogen interaction is demonstrated using TDI-2760, a small inhibitory compound14. These methods, both individually and together, allow for rapid and straightforward analysis of in vitro fibrin clot formation.

<table>
	<tbody>
		<tr>
			<td>Fibriogen, Plasminogen-Depleted, Plasma</td>
			<td>EMD Millipore</td>
			<td>341578</td>
			<td>keep lid parafilm wrapped to avoid exposure to moisture</td>
		</tr>
		<tr>
			<td>Beta-Amyloid (1-42), Human</td>
			<td>Anaspec</td>
			<td>AS-20276</td>
			<td></td>
		</tr>
		<tr>
			<td>Thrombin from human plasma</td>
			<td>Sigma-Aldrich</td>
			<td>T7009</td>
			<td></td>
		</tr>
		<tr>
			<td>1,1,1,3,3,3-Hexafluoro-2-propanol, Greater Than or Equal to 99%</td>
			<td>Sigma-Aldrich</td>
			<td>105228</td>
			<td></td>
		</tr>
		<tr>
			<td>DIMETHYL SULFOXIDE (DMSO), STERILE-FILTERED</td>
			<td>Sigma-Aldrich</td>
			<td>D2438</td>
			<td></td>
		</tr>
		<tr>
			<td>Pierce BCA Protein Assay Kit</td>
			<td>Thermo Scientific</td>
			<td>23225</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris Base</td>
			<td>Fischer Scientific</td>
			<td>BP152</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Fischer Scientific</td>
			<td>BP310</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Fischer Scientific</td>
			<td>S271</td>
			<td></td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Fischer Scientific</td>
			<td>C70</td>
			<td></td>
		</tr>
		<tr>
			<td>Filter Syringe, 0.2&#181;M, 25mm</td>
			<td>Pall</td>
			<td>4612</td>
			<td></td>
		</tr>
		<tr>
			<td>Millex Sterile Syringe Filters, 0.1 um, PVDF, 33 mm dia.</td>
			<td>Millipore</td>
			<td>SLVV033RS</td>
			<td></td>
		</tr>
		<tr>
			<td>Solid 96 Well Plates High Binding Certified Flat Bottom</td>
			<td>Fischer Scientific</td>
			<td>21377203</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectramax Plus384</td>
			<td>Molecular Devices</td>
			<td>89212-396</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge, 5417R</td>
			<td>Eppendorf</td>
			<td>5417R</td>
			<td></td>
		</tr>
		<tr>
			<td>Branson 200 Ultrasonic Cleaner</td>
			<td>Fischer Scientific</td>
			<td>15-337-22</td>
			<td></td>
		</tr>
		<tr>
			<td>Lab Rotator</td>
			<td>Thermo Scientific</td>
			<td>2314-1CEQ</td>
			<td></td>
		</tr>
		<tr>
			<td>Spare washers for cover slip holder</td>
			<td>Tousimis</td>
			<td>8766-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Narrow Stem Pipets - Sedi-Pet</td>
			<td>Electron Microscopy Sciences (EMS)</td>
			<td>70967-13</td>
			<td></td>
		</tr>
		<tr>
			<td>Sample holder for CPD (Cover slip holder)</td>
			<td>Tousimis</td>
			<td>8766</td>
			<td></td>
		</tr>
		<tr>
			<td>Mount Holder Box, Pin Type</td>
			<td>Electron Microscopy Sciences (EMS)</td>
			<td>76610</td>
			<td></td>
		</tr>
		<tr>
			<td>Round glass cover slides (12 mm)</td>
			<td>Hampton Research</td>
			<td>HR3-277</td>
			<td></td>
		</tr>
		<tr>
			<td>10% Glutaraldehyde</td>
			<td>Electron Microscopy Sciences (EMS)</td>
			<td>16120</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Decon Labs</td>
			<td>11652</td>
			<td></td>
		</tr>
		<tr>
			<td>24 well plate</td>
			<td>Falcon</td>
			<td>3047</td>
			<td></td>
		</tr>
		<tr>
			<td>Na Cacodylate</td>
			<td>Electron Microscopy Sciences (EMS)</td>
			<td>11652</td>
			<td></td>
		</tr>
		<tr>
			<td>SEM Stubs, Tapered end pin.</td>
			<td>Electron Microscopy Sciences (EMS)</td>
			<td>75192</td>
			<td></td>
		</tr>
		<tr>
			<td>PELCO Tabs, Carbon Conductive Tabs, 12mm OD</td>
			<td>Ted Pella</td>
			<td>16084-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Autosamdri-815 Critical Point Dryer with Gold/Palladium target</td>
			<td>Tousimis</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Denton Desk IV Coater</td>
			<td>Denton Vacuum</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Leo 1550 FE-SEM</td>
			<td>Carl Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Smart SEM Software</td>
			<td>Carl Zeiss</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

analysis of &#946;-amyloid-induced abnormalities on fibrin clot structure by spectroscopy and scanning electron microscopy

This article presents methods for generating in vitro fibrin clots and analyzing the effect of beta-amyloid (A&#946;) protein on clot formation and structure by spectrometry and scanning electron microscopy (SEM). A&#946;, which forms neurotoxic amyloid aggregates in Alzheimer&#39;s disease (AD), has been shown to interact with fibrinogen. This A&#946;-fibrinogen interaction makes the fibrin clot structurally abnormal and resistant to fibrinolysis. A&#946;-induced abnormalities in fibrin clotting may also contribute to cerebrovascular aspects of the AD pathology such as microinfarcts, inflammation, as well as, cerebral amyloid angiopathy (CAA). Given the potentially critical role of neurovascular deficits in AD pathology, developing compounds which can inhibit or lessen the A&#946;-fibrinogen interaction has promising therapeutic value. In vitro methods by which fibrin clot formation can be easily and systematically assessed are potentially useful tools for developing therapeutic compounds. Presented here is an optimized protocol for in vitro generation of the fibrin clot, as well as analysis of the effect of A&#946; and A&#946;-fibrinogen interaction inhibitors. The clot turbidity assay is rapid, highly reproducible and can be used to test multiple conditions simultaneously, allowing for the screening of large numbers of A&#946;-fibrinogen inhibitors. Hit compounds from this screening can be further evaluated for their ability to ameliorate A&#946;-induced structural abnormalities of the fibrin clot architecture using SEM. The effectiveness of these optimized protocols is demonstrated here using TDI-2760, a recently identified A&#946;-fibrinogen interaction inhibitor.

In the in vitro clotting (turbidity) assay, the enzyme thrombin cleaves fibrinogen, resulting in the formation of the fibrin network24. This fibrin clot formation causes scattering of the light passing through the solution, resulting in increased turbidity (Figure 1), plateauing before the end of the reading period (Figure 2, green). When the fibrinogen was incubated in the presence of A&#946;42, ...

Watch this Scientific Journal Video about Analysis of ÃŽÂ²-Amyloid-induced Abnormalities on Fibrin Clot Structure by Spectroscopy and Scanning Electron Microscopy at JoVE.com

Analysis of ÃƒÆ’Ã…Â½Ãƒâ€šÃ‚Â²-Amyloid-induced Abnormalities on Fibrin Clot Structure by Spectroscopy and Scanning Electron Microscopy

Presented here are two methods that can be used individually or in combination to analyze the effect of beta-amyloid on fibrin clot structure. Included is a protocol for creating an in vitro fibrin clot, followed by clot turbidity and scanning electron microscopy methods.

Analysis of &#946;-Amyloid-induced Abnormalities on Fibrin Clot Structure by Spectroscopy and Scanning Electron Microscopy

This article presents methods for generating in vitro fibrin clots and analyzing the effect of beta-amyloid (A&#946;) protein on clot formation and ...

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Negative stain electron microscopy (EM) allows relatively simple and quick observation of macromolecules and macromolecular complexes through the use of ...

Analyzing Dynamic Protein Complexes Assembled On and Released From Biolayer Interferometry Biosensor Using Mass Spectrometry and Electron Microscopy

In vivo, proteins are often part of large macromolecular complexes where binding specificity and dynamics ultimately dictate functional outputs. In this ...

Mitochondria and Endoplasmic Reticulum Imaging by Correlative Light and Volume Electron Microscopy

Cellular organelles, such as mitochondria and endoplasmic reticulum (ER), create a network to perform a variety of functions. These highly curved ...

Transverse Sectioning of Mature Rice (Oryza sativa L.) Kernels for Scanning Electron Microscopy Imaging Using Pipette Tips as Immobilization Support

Transverse Sectioning of Mature Rice Oryza sativa L. Kernels for Scanning Electron Microscopy Imaging Using Pipette Tips as Immobilization Support

Starch granules (SGs) exhibit different morphologies depending on the plant species, especially in the endosperm of the Poaceae family. Endosperm ...

Single Cell Analysis Of Transcriptionally Active Alleles By Single Molecule FISH

Gene transcription is an essential process in cell biology, and allows cells to interpret and respond to internal and external cues. Traditional bulk ...

Single Particle Cryo-Electron Microscopy: From Sample to Structure

Cryo-electron microscopy (cryoEM) is a powerful technique for structure determination of macromolecular complexes, via single particle analysis (SPA). The ...

Micropatterning Transmission Electron Microscopy Grids to Direct Cell Positioning within Whole-Cell Cryo-Electron Tomography Workflows

Whole-cell cryo-electron tomography (cryo-ET) is a powerful technology that is used to produce nanometer-level resolution structures of macromolecules ...