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At least 1,225 records · Page 68Linked to original sources
PubMed1994

Direct visualization of lipid aggregates in native human bile by light- and cryo-transmission electron-microscopy.

The evolution of microstructures present in human gallbladder and hepatic bile was observed simultaneously by video-enhanced light microscopy (VELM) and transmission electron microscopy of vitrified specimens (cryo-TEM), as a function of time after withdrawal from patients. Fresh centrifuged gallbladder bile samples contained small (6 nm) spherical micelles in coexistence with vesicles (40 nm). Out of the seven bile samples investigated four contained, in addition, two types of elongated aggregates that have not been previously described. Uncentrifuged gallbladder bile also contained a mixture of ribbon- and plate-like crystals seen by VELM, but not by cryo-TEM. In aged (3-6-week-old) gallbladder bile samples VELM also revealed spiral and helical crystal structures. No such crystals were present in hepatic bile samples, although microcrystals, not observable by VELM were seen by cryo-TEM in addition to micelles and vesicles. The similarity of these observations to those observed in bile models lends strong support for the validity of the model systems. Furthermore, the presence of microcrystals in hepatic bile samples, apparently devoid of crystals by light microscopy, indicates that under certain conditions the common criterion of 'nucleation time' (NT), based on light microscopy, does not represent the real time of nucleation. In the human bile samples investigated in this study the dissociation between NT and the time of observation of microcrystals was seen in hepatic but not in gallbladder bile samples. Hence, crystal growth may be rate limiting only in dilute biles.

Bile↗
PubMedDate not supplied

Scanning tunneling and transmission electron microscopy on identical areas of biological specimens.

A methodology for tip and specimen-support manufacturing is described which allows for scanning tunneling microscopy (STM) and transmission electron microscopy (TEM) on identical areas of biological specimens, at comparable resolution. Topographs and dI/ds-maps were used to investigate tip-specimen interaction on native air-dried phage T4 polyheads where individual capsomeres and structural alterations upon repetitive scans have been observed at a tunnel current of 0.5 pA.

Microscopy, Electron, Scanning↗
PubMed1999

Evaluation of neutrophil structure and function by electron microscopy: cytochemical studies.

Methods for studying human neutrophils at the ultrastructural level by enzyme cytochemistry and immunocytochemistry are presented. The focus of these methods is on the analysis of the alkaline phosphatase-positive secretory organelle of these cells. These methods provide unique information which, when coupled with biochemical studies, provide for the most complete analysis of neutrophil structure and function.

Alkaline Phosphatase↗