In Vivo Action of Vanillin on Delay Time Determined by Magnetic Relaxation

Hemoglobin ◽  
2005 ◽  
Vol 29 (3) ◽  
pp. 181-187 ◽  
Author(s):  
Adolfo Fernández García ◽  
Carlos Cabal ◽  
Jorge Losada ◽  
Eloy Álvarez ◽  
Catalina Soler ◽  
...  
Keyword(s):  
Delay Time ◽  
Magnetic Relaxation

scholarly journals Fragility and structure of hemoglobin S fibers and gels and their consequences for gelation kinetics and rheology

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 573-579 ◽  
Author(s):  
RW Briehl ◽  
AE Guzman
Keyword(s):  
Delay Time ◽  
Hemoglobin Concentration ◽  
Differential Interference Contrast ◽  
Cell Disease ◽  
Mechanical Perturbation ◽  
Hemoglobin S ◽  
Gelation Kinetics ◽  
A Value ◽  
Cross Links

Abstract Pathogenesis in sickle cell disease depends on whether red blood cells can pass the microvasculature during the delay time before hemoglobin S gelation and cell rigidification occur. Here we observe individual hemoglobin S fibers by differential interference contrast (DIC) microscopy and show that hemoglobin S gels and fibers are fragile and easily broken by mechanical perturbation, and that breakage results in vast acceleration of gelation kinetics due to the creation of new, growing fiber-ends. Hence, in vivo this may be an important factor, in addition to hemoglobin concentration and degree of deoxygenation, that governs delay time and pathogenesis. Pathogenesis also depends on gel rheology and cell rigidification, which depend on fiber cross-linking. We show different mechanisms by which X-shaped, Y-shaped, and “zippering” cross-links form. Finally, we estimate the “on” rate constant for fiber growth to be about 200 mmol/(L.s) and obtain a value for the heterogeneous nucleation rate at 13.5 mmol/L heme.

The Development of Non-Radiative Probes for In Vivo Applications

2003 ◽  
Author(s):  
Andrew Tsourkas ◽  
Lee Josephson ◽  
Ralph Weissleder
Keyword(s):  
Relaxation Time ◽  
Magnetic Relaxation ◽  
Magnetic Particles ◽  
Superparamagnetic Iron Oxide ◽  
Great Promise ◽  
T2 Relaxation Time ◽  
T2 Relaxation ◽  
Fluorescence Measurements

Recently, the field of activatable probes has been extended from fluorescence to magnetic resonance (MR). Magnetic relaxation switches take advantage of the change in T2 relaxation time that occurs upon binding of multiple bioconjugated superparamagnetic iron-oxide nanoparticles to a target. Here, we use a model system to detect biotinilated BSA using switchable magnetic particles. The presence of the biotinilated BSA results in the aggregation of nanoparticles and leas to a substantial decrease in the T2 relaxation time. Magnetic relaxation switches show great promise for clinical in vitro diagnostics and in vivo imaging since changes in T2 are independent of the sample medium. Tests can be performed in turbid solutions without loss of sensitivity, unlike with fluorescence measurements.

scholarly journals Fragility and structure of hemoglobin S fibers and gels and their consequences for gelation kinetics and rheology

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 573-579
Author(s):  
RW Briehl ◽  
AE Guzman
Keyword(s):  
Delay Time ◽  
Hemoglobin Concentration ◽  
Differential Interference Contrast ◽  
Cell Disease ◽  
Mechanical Perturbation ◽  
Hemoglobin S ◽  
Gelation Kinetics ◽  
A Value ◽  
Cross Links

Pathogenesis in sickle cell disease depends on whether red blood cells can pass the microvasculature during the delay time before hemoglobin S gelation and cell rigidification occur. Here we observe individual hemoglobin S fibers by differential interference contrast (DIC) microscopy and show that hemoglobin S gels and fibers are fragile and easily broken by mechanical perturbation, and that breakage results in vast acceleration of gelation kinetics due to the creation of new, growing fiber-ends. Hence, in vivo this may be an important factor, in addition to hemoglobin concentration and degree of deoxygenation, that governs delay time and pathogenesis. Pathogenesis also depends on gel rheology and cell rigidification, which depend on fiber cross-linking. We show different mechanisms by which X-shaped, Y-shaped, and “zippering” cross-links form. Finally, we estimate the “on” rate constant for fiber growth to be about 200 mmol/(L.s) and obtain a value for the heterogeneous nucleation rate at 13.5 mmol/L heme.

scholarly journals Kinetics of hemoglobin S polymerization and gelation under shear: I. Shape of the viscosity progress curve and dependence of delay time and reaction rate on shear rate and temperature

Blood ◽  
1993 ◽  
Vol 81 (9) ◽  
pp. 2420-2428 ◽  
Author(s):  
RW Briehl ◽  
P Nikolopoulou
Keyword(s):  
Delay Time ◽  
Hemoglobin Concentration ◽  
Exponential Rate ◽  
Clinical Issue ◽  
Hemoglobin S ◽  
Shear Rates ◽  
Progress Curve ◽  
Pass Through

Abstract Polymerization and gelation of deoxyhemoglobin S makes red blood cells (RBCs) rigid and is the immediate basis of pathogenesis in sickle cell disease. Hence, characterization of hemoglobin S viscosity and its time- dependent development as RBCs pass through the microvasculature is important in understanding pathogenesis. Because RBCs and the intraerythrocytic milieu in vivo are subject to shear, the shear dependence of polymerization kinetics is also important. In steady- state cone-plate viscometry we find: (1) gelation under shear progresses exponentially with time; (2) shear markedly increases exponential rate and (3) shortens delay time independent of when in the delay time it is applied; (4) shear greatly decreases the temperature dependence of the exponential rate and delay time; (5) simultaneous with its acceleratory effect on polymerization, shear breaks down gel structure. We conclude that shear acts to accelerate gelation by breaking fibers and creating new growing ends, a process that occurs in addition to the homogeneous and heterogeneous nucleation of new fibers that occurs in the absence of shear. Fibers that break are part of a gel network rather than in free solution. The shear dependence of gelation rates means that the critical clinical issue, whether the delay time is long enough and gelation slow enough to permit deoxygenated cells to pass through the microvasculature before they rigidify, depends on in vivo shear rates as well as on degree of unsaturation and hemoglobin concentration.

Delay time of hemoglobin S polymerization prevents most cells from sickling in vivo

Science ◽  
1987 ◽  
Vol 237 (4814) ◽  
pp. 500-506 ◽  
Author(s):  
A Mozzarelli ◽  
J Hofrichter ◽  
W. Eaton
Keyword(s):  
Delay Time ◽  
Hemoglobin S

scholarly journals Kinetics of hemoglobin S polymerization and gelation under shear: I. Shape of the viscosity progress curve and dependence of delay time and reaction rate on shear rate and temperature

Blood ◽  
1993 ◽  
Vol 81 (9) ◽  
pp. 2420-2428
Author(s):  
RW Briehl ◽  
P Nikolopoulou
Keyword(s):  
Delay Time ◽  
Hemoglobin Concentration ◽  
Exponential Rate ◽  
Clinical Issue ◽  
Hemoglobin S ◽  
Shear Rates ◽  
Progress Curve ◽  
Pass Through

Polymerization and gelation of deoxyhemoglobin S makes red blood cells (RBCs) rigid and is the immediate basis of pathogenesis in sickle cell disease. Hence, characterization of hemoglobin S viscosity and its time- dependent development as RBCs pass through the microvasculature is important in understanding pathogenesis. Because RBCs and the intraerythrocytic milieu in vivo are subject to shear, the shear dependence of polymerization kinetics is also important. In steady- state cone-plate viscometry we find: (1) gelation under shear progresses exponentially with time; (2) shear markedly increases exponential rate and (3) shortens delay time independent of when in the delay time it is applied; (4) shear greatly decreases the temperature dependence of the exponential rate and delay time; (5) simultaneous with its acceleratory effect on polymerization, shear breaks down gel structure. We conclude that shear acts to accelerate gelation by breaking fibers and creating new growing ends, a process that occurs in addition to the homogeneous and heterogeneous nucleation of new fibers that occurs in the absence of shear. Fibers that break are part of a gel network rather than in free solution. The shear dependence of gelation rates means that the critical clinical issue, whether the delay time is long enough and gelation slow enough to permit deoxygenated cells to pass through the microvasculature before they rigidify, depends on in vivo shear rates as well as on degree of unsaturation and hemoglobin concentration.

Fine Structural Changes in the Microvasculature of the Mouse Pinna: Aging and Radiation Injury

1974 ◽  
Vol 32 ◽  
pp. 54-55
Author(s):  
S. Phyllis Steamer ◽  
Rosemarie L. Devine
Keyword(s):  
Structural Changes ◽  
Radiation Treatment ◽  
Arterial Stenosis ◽  
Ultrastructural Changes ◽  
Vascular Effects ◽  
Microvascular Changes ◽  
Surrounding Connective Tissue ◽  
Fission Neutrons ◽  
Total Body

The importance of radiation damage to the skin and its vasculature was recognized by the early radiologists. In more recent studies, vascular effects were shown to involve the endothelium as well as the surrounding connective tissue. Microvascular changes in the mouse pinna were studied in vivo and recorded photographically over a period of 12-18 months. Radiation treatment at 110 days of age was total body exposure to either 240 rad fission neutrons or 855 rad 60Co gamma rays. After in vivo observations in control and irradiated mice, animals were sacrificed for examination of changes in vascular fine structure. Vessels were selected from regions of specific interest that had been identified on photomicrographs. Prominent ultrastructural changes can be attributed to aging as well as to radiation treatment. Of principal concern were determinations of ultrastructural changes associated with venous dilatations, segmental arterial stenosis and tortuosities of both veins and arteries, effects that had been identified on the basis of light microscopic observations. Tortuosities and irregularly dilated vein segments were related to both aging and radiation changes but arterial stenosis was observed only in irradiated animals.

Induction and Differentiation of Dental Epithelium in Vivo and in Vitro

1982 ◽  
Vol 40 ◽  
pp. 142-145
Author(s):  
E. J. Kollar
Keyword(s):  
Connective Tissue ◽  
Oral Mucosa ◽  
Basal Lamina ◽  
Functional Derivatives ◽  
Specific Source ◽  
Dental Epithelium ◽  
Connective Tissue Stroma

The differentiation and maintenance of many specialized epithelial structures are dependent on the underlying connective tissue stroma and on an intact basal lamina. These requirements are especially stringent in the development and maintenance of the skin and oral mucosa. The keratinization patterns of thin or thick cornified layers as well as the appearance of specialized functional derivatives such as hair and teeth can be correlated with the specific source of stroma which supports these differentiated expressions.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

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