Determination of the integral refractive index of cells in suspension by digital holographic phase contrast microscopy

2008 ◽  
Author(s):  
Sebastian Kosmeier ◽  
Björn Kemper ◽  
Patrik Langehanenberg ◽  
Ilona Bredebusch ◽  
Jürgen Schnekenburger ◽  
...  
Keyword(s):  
Refractive Index ◽  
Phase Contrast ◽  
Phase Contrast Microscopy ◽  
Contrast Microscopy ◽  
Refractive Index Of Cells

Integral refractive index determination of living suspension cells by multifocus digital holographic phase contrast microscopy

2007 ◽  
Vol 12 (5) ◽  
pp. 054009 ◽  
Author(s):  
Björn Kemper ◽  
Sebastian Kosmeier ◽  
Patrik Langehanenberg ◽  
Gert von Bally ◽  
Ilona Bredebusch ◽  
...  
Keyword(s):  
Refractive Index ◽  
Phase Contrast ◽  
Phase Contrast Microscopy ◽  
Suspension Cells ◽  
Contrast Microscopy

An interferometer microscope

1950 ◽  
Vol 204 (1077) ◽  
pp. 170-187 ◽  
Keyword(s):  
Refractive Index ◽  
Epithelial Cells ◽  
Optical Thickness ◽  
Phase Contrast ◽  
Phase Contrast Microscopy ◽  
Object Plane ◽  
Operational Procedure ◽  
Contrast Microscopy ◽  
New Type

Some of the drawbacks of conventional phase contrast microscopy are enumerated and the desirability of an interferometer microscope is indicated. A number of existing ways of achieving this are described, together with their merits and drawbacks. A new type of interferometer microscope which avoids some of these disadvantages is described, together with its operational procedure. The conditions covering coherence in the object plane are investigated and a simple approximation for evaluating the coherence is derived. An elementary discussion of contrast arising from phase or amplitude objects is given, and a number of experimental results are presented as photo-micrograms. Finally, a method for the accurate measurement of the optical thickness of an object is described, with the results of a determination of the refractive index of the cytoplasm of epithelial cells.

Increased Fraction of Circulating Activated Platelets in Acute and Previous Cerebrovascular Ischemia

1998 ◽  
Vol 80 (08) ◽  
pp. 298-301 ◽  
Author(s):  
Andreas Ruf ◽  
Axel Vogt ◽  
Christoph Lichy ◽  
Florian Buggle ◽  
Heinrich Patscheke ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Phase Contrast ◽  
Matched Control ◽  
Shape Change ◽  
Antigen Expression ◽  
Phase Contrast Microscopy ◽  
Activated Platelets ◽  
Contrast Microscopy ◽  
Age And Sex

SummaryDetermination of circulating activated platelets may be helpful to estimate the prognosis and to stratify therapies in arterial vascular disorders including stroke. We used flow cytometry and phase contrast microscopy to study whether the fraction of platelets expressing p-selectin and CD63 and the fraction of platelets with shape change are increased in patients with acute and previous cerebrovascular ischemia.The proportion of platelets expressing activation dependent antigens was higher in patients with acute (n = 24; p-selectin: 8.23 ± 4.21%; CD63: 3.53 ± 2.53%) and with previous cerebrovascular ischemia (n = 46; 3.86 ± 1.98%; 2.80 ± 1.79%) as compared to age- and sex-matched control subjects (n = 35; 2.17 ± 0.96%; 1.79 ± 0.75%; p ≤0.005, respectively). In patients with previous ischemia, there was no difference between treatment with aspirin (n = 25) or phenprocoumon (n = 21). Hypertension, diabetes mellitus and smoking were not associated with increased antigen expression (analysis of variance). The fraction of discoid platelets and platelet counts were not significantly different between groups.Our results indicate increased expression of platelet neoantigens in acute and to a less degree in previous cerebrovascular ischemia. Ongoing platelet activation after cerebrovascular ischemia despite therapy with aspirin or phenprocoumon indicates that new anti-platelet drugs may be of benefit for these patients. Flow cytometry appears to be a useful tool to assess platelet function in cerebrovascular ischemia.

Determination of transition curves of high-Tc superconductors by phase contrast microscopy

1995 ◽  
Vol 507 (2) ◽  
pp. 136-143
Author(s):  
Cl. Kriebel ◽  
O. Hoffels ◽  
R. Borowski ◽  
H. Gottschalk ◽  
H. Alexander ◽  
...  
Keyword(s):  
Phase Contrast ◽  
Phase Contrast Microscopy ◽  
High Tc Superconductors ◽  
High Tc ◽  
Contrast Microscopy ◽  
Transition Curves

Refractometry of Living Cells

1954 ◽  
Vol s3-95 (32) ◽  
pp. 399-423
Author(s):  
R. BARER ◽  
S. JOSEPH
Keyword(s):  
Refractive Index ◽  
Phase Contrast ◽  
Protein Concentration ◽  
Living Cells ◽  
Phase Contrast Microscopy ◽  
Immersion Medium ◽  
First Approximation ◽  
Cent Increase ◽  
Contrast Microscopy ◽  
The Mean

The principles underlying a new method of refractometry of living cells are discussed. The method was evolved from the chance observation that the amoebocytes of the blood of the earthworm, examined in their own blood, appeared bright instead of dark by positive phase-contrast microscopy. This was shown to be due to the presence of dissolved haemoglobin which raised the refractive index of the medium above that of the cytoplasm. In order to determine the refractive index of the latter it was only necessary to dilute the blood until the cytoplasm became virtually invisible. Non-pigmented proteins and other high molecular weight substances have now been substituted for haemoglobin. The nature of the initial observations suggested that if the cell could be regarded to a first approximation as being composed entirely of proteins, the cytoplasmic protein concentration could be equated to the protein concentration of the immersion medium which made the cell appear with minimum contrast. This would only be true if equal concentrations of different proteins in solution had the same refractive index. The nature of refractive index and its relationship to density are discussed and it is shown that for nearly all unconjugated proteins so far investigated the specific refraction increments (i.e. the increase in refractive index per 1 per cent, increase in concentration) have almost the same values (.00185±2 per cent.). The effects of many factors such as pH, salts, temperature, wavelength, concentration, and nature of the solvent are discussed. Since living cells contain substances other than proteins the specific refraction increments of protein derivatives, lipides, carbohydrates, and salts are considered and it is shown that the presence of moderate amounts of such substances is unlikely to affect the refractive index of cells to any great extent. It is suggested that the mean specific refraction increment of protoplasm should be taken as .0018 and that this value can be used in order to calculate the solid and water content of protoplasm from values of refractive index.

Phase Contrast Morphology of Coagulation Clot Maturation and Fibrinolysis

1965 ◽  
Vol 13 (01) ◽  
pp. 047-059 ◽  
Author(s):  
J. R Jannach
Keyword(s):  
Refractive Index ◽  
Phase Contrast ◽  
Positive Phase ◽  
Phase Contrast Microscopy ◽  
Clot Retraction ◽  
Fibrin Formation ◽  
Contrast Microscopy

SummaryMorphologic observations of coagulation, clot maturation and fibrinolysis in thin standardized clots were presented using negative and positive phase contrast microscopy. The study described the beginning of fibrin formation in centers away from platelets and platelet clumps but usually associated with platelet fragments. Although the preparations failed to reveal clot retraction, the fibrin strands did show a change in refractive index. Intact clot preparations were demonstrated several weeks after incubation at 37° 0.The observation of greatest significance, in the light of recent studies accentuating the role of platelets in hemostasis, was the lysis of platelets and platelet clumps which had undergone viscous metamorphosis. This action of plasmin on platelets may be of great importance in the prevention of hemostasis in the fibrinolytic syndrome and the destruction of damaged platelets in the normal circulation.

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