The fine structure of pancreatic stones as shown by scanning electron microscopy and x-ray probe microanalyser
SummaryTo delineate the process of pancreatic stone formation, stones from four patients were studied with a scanning electron microscope and X-ray probe microanalyser.The stones consisted of a central core and surrounding shell. Two kinds of stones were demonstrated:one had a core composed of a calcium-rich amorphous substance and interlacing fibrils; the other had a core consisting of multiple cavities with smooth walls composed of a calcium-deficient amorphous substance.The shells showed a common structure: zones of layers or bands of a calcium-rich amorphous substance, network fibrils filled with a calcium-rich amorphous substance, and laminated parallelogrammic or polygonal plates of calcite parallel to the surface in one layer and oblique or perpendicular in the next layer. Calcium was in the crypto-crystalline state as well as crystalline state of calcite. Crystalline calcite showed spiral and epitaxial growth along with findings of dissolution, resembling cholesterol crystals of gall stones. Pancreatic stones are probably formed through central core formation and layered growth of a shell. Comparison of stones and protein plugs suggests that protein plugs can grow to stones with calcite deposition accompanied by precipitation of network fibrils and an amorphous substance.
Trypsin and lactoferrin levels in pure pancreatic juice in patients with pancreatic disease.
Levels of immunoreactive trypsin were measured in pure pancreatic juice obtained endoscopically from 44 patients with suspected pancreatic disease. Patients with pancreatic cancer all had low trypsin concentrations (median 3.6 micrograms/ml, range 0.6--12.0), but those with chronic pancreatitis had very variable levels (median 14.2 micrograms/ml, range 3.2--76.8), showing a considerable overlap with patients without pancreatic disease (median 37.1 micrograms/ml, range 10.4--66.0). When levels of lactoferrin in pancreatic juice were measured, all patients with chronic pancreatitis were found to have much higher levels (all greater than 900 ng/ml) than control subjects or patients with pancreatic cancer (all less than 400 ng/ml). The combined measurement of trypsin and lactoferrin in pure pancreatic juice appeared to be more promising than any other currently available test for the separation of patients with pancreatic cancer from those with chronic pancreatitis.
Application of 2μm Tm Laser on Biomedicine
Continuous wave Thulium laser emits at wavelength of 2.0 mm, which is well suited for tissue ablationand thermally stimulating cutaneous nerves due to its high absorption by water. 2 mm laser can be transmitted suffi-ciently by common quartz fibers and it is safe for eyes. A brief introduction of principle of 2 mm CW Tm Laser is giv-en, analyzing the photothermal modeling of thulium laser-tissue interaction, comparing 2 mm CW Tm Laser with tradi-tional laser.