Mucoid impaction of bronchi. A scanning electron microscopic study

An example of mucoid impaction in the culminal bronchus in a potentially asthmatic child is related. Histological sections of the plug showed the characteristic pattern with clusters of eosinophils and other cells within the impacted mucus, which consisted of mainly sulfated glycoproteins. Scanning electron microscopy revealed new data on the three-dimensional structure of the plug. Ten to fifteen micron thick fascicles of partially rolled-up mucous fibres surrounded wide meshes filled with eosinophils and other components. As far as can be determined, this is the first reported ultrastructural description of this particular lesion.

[Presence of filamentary secretory granules in the mucous cells of human bronchial glands]

Secretory granules containing 6-8 nm fine filaments are described in mucous cells of human bronchial glands. In contrast with the strongly marked classical mucous granules, filamentary granules exhibit weak positivity with Thiéry's method providing an easy characterization. Exocytosis in glandular lumen are often observed. These undescribed filaments may probably represent an usual component of fibrillar matrix in bronchial mucus.

New photoactivatable cyclic nucleotides produce intracellular jumps in cyclic AMP and cyclic GMP concentrations

The cyclic nucleotides cyclic AMP and cyclic GMP are important intracellular messengers mediating the responses to neurotransmitters and neurohormones and regulating cellular function over a wide range of time scales. Despite the widespread acceptance of this second messenger mechanism in many systems, much remains unknown about their mechanism of action, except that such events are associated with increases or decreases in intracellular cyclic nucleotides. Quantitative descriptions of cyclic nucleotide-dependent processes are hampered by the absence of a means by which intracellular cyclic nucleotide concentrations can be accurately controlled. We have now designed, synthesized and characterized new, substituted photolabile cyclic nucleotide analogues, the 4,5-dimethoxy-2-nitrobenzyl esters of cyclic AMP and cyclic GMP (Fig. 1), which are physiologically inert before irradiation and which liberate free cyclic AMP or cyclic GMP on absorption of a photon. The thermal properties and photolysis rates and efficiencies of light-induced release of cyclic nucleotides from these analogues are more favourable than for the simple o-nitrobenzyl derivatives used previously. These molecules should permit intracellular "concentration jumps' of cyclic AMP or cyclic GMP to be produced in cells under physiological investigation with spatial and temporal resolution unmatched by conventional techniques.

Determination of organ volume by single-photon emission tomography

A method for estimation of organ volume is proposed, based on analysis of individual slices obtained from SPET images. In a phantom simulating clinical circumstances, the data show that the level a threshold at 46% of the maximum activity predicts most closely the true volume over a wide range above one liter. The level at 45% predicted better volumes of less than one liter. For phantoms of 839 ml or less, the error was 6.3 ml (one standard error of estimation). This level seems to be independent of the plane or position of the phantom and also independent of the amount of scattering material around it. Nonradioactive voids ("holes") within a phantom may be included or excluded at will when their edges are not tangent to the edge of the phantom. In such cases, their edges are not distinguishable from the edge of the phantom and their volumes are excluded. Knowledge of organ volumes has both diagnostic and therapeutic importance and could lead to a more precisely quantitated total of the radioactivity contained in an organ or space.