PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “MICROSCOPY, PHASE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources
PubMed1990

Three serotypes of Norwalk-like virus demonstrated by solid-phase immune electron microscopy.

Solid phase immune electron microscopy (SPIEM) was used to investigate the serological differences between Norwalk-like virus (NLV) strains from five different outbreaks within the United Kingdom. The existence of two previously demonstrated serotypes, Lewis et al. (Journal of Clinical Microbiology 26:938-942, 1988), was confirmed by the use of whole convalescent sera and purified IgM. A third serotype was found to be the agent of two recent hospital outbreaks and could similarly be typed by use of whole sera or pure IgM. Paired sera were available for two of the three serotypes and demonstrated rising antibody levels. These antibody rises were also specific for the infecting serotype. However, two serum pairs from a later outbreak gave antibody rises to all three serotypes, although much higher counts were produced with the infecting serotype. SPIEM is a useful method for distinguishing NLV serotypes and can also be used to detect specific IgM and to demonstrate seroconversion. Cross-reacting antibodies, possibly anamnestic in origin, can occur after natural infection and could cause confusion in typing virus unless further evidence of the identity of the infecting agent is obtained.

Adult↗
PubMed1980

A new phenomenon (SMOG) associated with solid phase immune electron microscopy.

Solid phase immune electron microscopy (SPIEM) has been used to study the interaction of virus and antibody both quickly and with economy of reagents. Unexpectedly, the present study shows that when virus-coated grids are floated on drops of specific antibody the virus particles migrate to form complexes. This has been termed specific migration on the grid (SMOG) and it is suggested that it can be used both to assess the properties of an antiserum and to make virus more readily detectable. The mechanism by which SMOG occurs is not understood but various possibilities are discussed.

Antibodies, Viral↗
PubMed1984

Automated analysis of living cells through the quantitative use of automated phase contrast microscopy.

A simplified theory of image formation in phase contrast microscopy is presented. It is shown that the phase shift induced in light (related to the refractive index) by the observed object can be reconstructed, point by point, from the phase-contrast digitally sampled image through an appropriate algorithm. This allows one to make quantitative observations on unstained, living cells.

Animals↗
PubMed1982

A simple quantitative analysis of phase contrast microscopy, not restricted to objects of very low retardation.

A simple vector analysis of the diffraction of light by an ideal, extended phase grating suggests that irrespective of the amount of retardation imposed on the light passing through a transparent microscopic object the diffracted light leaving the object plane is precisely 90 degrees out of phase with the resultant direct (zero-order diffracted) light. In positive phase contrast microscopy, with a 90 degrees phase plate of transmittance T for the direct light, the image and halo respectively have intensities relative to the original illumination of (square root T.cos 1/2 phi - sin 1/2 phi)2 and (square root T.cos 1/2 phi + sin 1/2 phi)w. The empty background has an apparent intensity of T. Zero intensity of the image is seen if T = tan2(1/2 phi), and reversal of contrast if T less than tan2(1/4 phi). The same equations can be used to predict the intensities of the image and halo in negative phase contrast microscopy, if phi is replaced by (360 degrees - phi). Unlike the 'standard' description of phase contrast microscopy, exemplified by Barer's vector method, the present account is consistent with the conservation of energy and is not restricted to very small object retardations. Barer's method is, however, theoretically valid for objects of any shape, and the two approaches may perhaps be regarded as complementary.

Mathematics↗
PubMed2001

Imaging mixed lipid monolayers by dynamic atomic force microscopy.

Phase imaging with tapping mode atomic force microscopy (AFM) and force modulation microscopy were used to probe the mechanical properties of phase-separated lipid monolayers made of a mixture (0.25:0.75) of the surface-active lipopeptide surfactin and of dipalmitoylphosphatidylcholine (DPPC). The pi-A isotherms and the result of a molecular modeling study revealed a loose, 2-D liquid-like organization for the surfactin molecules and a closely packed, 2-D solid-like organization for DPPC molecules. This difference in molecular organization was responsible for a significant contrast in height, tapping mode phase and force modulation amplitude images. Phase imaging at light tapping, i.e., with a ratio of the set-point tapping amplitude with respect to the free amplitude A(sp)/A(0) approximately 0.9, showed larger phase shifts on the solid-like DPPC domains attributed to larger Young's modulus. However, contrast inversion was observed for A(sp)/A(0)<0.7, suggesting that at moderate and hard tapping the image contrast was dominated by the probe-sample contact area. Surprisingly, force modulation amplitude images showed larger stiffness for the liquid-like surfactin domains, suggesting that the contrast was dominated by contact area effects rather than by Young's modulus. These data emphasize the complex nature of the contrast mechanisms of dynamic AFM images recorded on mixed lipid monolayers.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2003

[Clinical use of phase-contrast microscopy in the differential diagnosis of microhematuria].

AIM: To evaluate phase-contrast microscopy in differential diagnosis of asymptomatic microhematuria in patients with asymptomatic microhematuria during the 1993-2000 period. PATIENTS AND METHODS: The study was performed at the Laboratory of Cytology, Department of Nephrology and Dialysis, Rijeka University Hospital Center, Rijeka, Croatia, and included 526 patients with asymptomatic hematuria referred from Urology Department. MAIN OUTCOME MEASURES: Presence of red blood cells (RBC), other cell types, other elements, and detritus. According to size and shape, RBCs were classified into 2 main categories: dysmorphic and isomorphic RBCs. The presence of > 80% of dysmorphic RBCs was recognized as glomerular hematuria. Isomorphic cell predominance was classified as postglomerular hematuria, and equal presence of both types was considered as mixed hematuria. RESULTS: Glomerular hematuria was found in 238 (45.2%), postglomerular hematuria in 181 (34.4%) and mixed hematuria in 22 (4.2%) patients. Additional diagnostic procedures in patients with glomerular hematuria included renal biopsy. In 89% of those patients glomerular disease was found. CONCLUSION: Phase-contrast microscopy is a simple, noninvasive and reliable diagnostic procedure in nephrology practice.

Adolescent↗