Kenneth A. Siegesmund

Relationship between distention and absorption in rat intestine: I. Effect of luminal volume on the morphology of the absorbing surface

Previous studies in vivo have suggested that distention of the intestinal lumen may enhance intestinal absorption by augmenting absorptive surface area. The precise anatomic mechanism for this increase in surface area, however, has not been explored in detail. We developed methods for rapidly freezing and fixing intestinal segments in situ in the nondistended or distended state. Distention led to a reduction in villus height (309.2 +/- 9.9 to 230.7 +/- 11.8 micron) and a marked increase in the width of intervillus space in both the transverse (50.4 +/- 4.8 to 298.0 +/- 24.8 micron) and longitudinal (15.2 +/- 3.4 to 76.0 +/- 10.6 micron) dimensions. There was, however, no absolute change in total mucosal surface area. The changes in morphology occurred instantaneously, were entirely reversible, and were demonstrated at pressures that occur spontaneously in the mammalian intestine. These studies demonstrate that luminal distention results in marked alterations in intestinal histology that promote increased access of luminal contents to intervillus transport sites in the intestine in vivo. The resulting alterations could lead to an increase in functional rather than absolute absorptive surface area.

Identification of Foreign Material in Lung by Energy Dispersive X-Ray Analysis: A New Approach to Silicosis

Conventional methods for the detection of foreign material in the lungs are not only difficult but make it impossible to study any relationship between the material and the surrounding tissue. The present study employs energy dispersive x-ray analysis and scanning electron microscopy as the basis of a rapid and accurate method for determining the amount of silicon in the lungs of normal subjects and subjects with silicosis. A statistical evaluation of the data suggests that a silicon/sulfur ratio below 0.2 may be considered normal, whereas, a ratio above 0.3 may be considered to indicate silicosis.

Identification of metals in lung from a patient with interstitial pneumonia.

Cobalt has been implicated as one of the possible causes of interstitial pneumonitis-fibrosis in industrial workers. This investigation is a light and electron microscopical study of a patient with interstitial pneumonitis-fibrosis. Energy dispersion x-ray analysis of electron-dense particles in the macrophages from the lung of this patient identify the particles as containing cobalt, iron, chromium, and nickel. This technique may be useful for the discrete localization and accurate identification of certain toxic elements in tissue.

Pulmonary Eosinophilic Granuloma: Electron Microscopic Detection of X-Bodies on Lung Lavage Cells and Transbronchoscopic Lung Biopsy in One Patient

Excerpt Eosinophilic granuloma is a granulomatous disorder of uncertain cause, manifested by reactive proliferation of histiocytes that may involve the lung either as part of disseminated disease o...