Endotracheal tube (ET) fire is the most frequent complication arising with laser surgery in the upper aerodigestive tract. No data are available about the safety of commonly used ETs when used with recently developed high-energy pulsed lasers, working with only a minimal thermal component but mainly photoablative. A comparative in vitro study was performed with three types of endotracheal tubes to assess their resistance to wall and cuff damage by the laser beams of two pulsed infrared solid-state lasers. ET perforation was attempted with the erbium:YAG (lambda = 2,930 nm) and holmium:YAG (lambda = 2,120 nm) lasers. For all experiments, a repetition rate of 5 Hz was used. The 2.5-microseconds holmium:YAG pulses were coupled into a nylon fibre of 400 microns diameter. The 2.0-microseconds erbium:YAG laser pulses were applied to ETs through a lens system providing a spot size diameter of 200 microns. Polyvinyl chloride and silicon ET segments were exposed to laser pulse energies from 97 to 500 mJ in the presence of different anaesthetic gas mixtures. The time from the onset of exposure to tube perforation was recorded. Thermal gradients following laser application were measured. Laser exposure was continued for up to 90 s, unless tube ignition occurred. At all energy levels tested, the photo-ablative mechanism of laser-tube interaction, with few thermal components, led to laser-induced tube ignition if an FiO2 > 21% for the holmium:YAG and 34% for the erbium:YAG laser was established. With increasing pulse energies, ET segments ignited sooner. MLT tubes performed best in the present safety test.

Aluminum Silicates↗

PubMedDate not supplied

Retroviruses in Kaposi's sarcoma in acquired immune deficiency syndrome (AIDS).

The ultrastructure of Kaposi's sarcoma (KS) of the oral mucosa in patients with acquired immune deficiency syndrome (AIDS) was examined electron microscopically. The tumour consisted of pleomorphic vascular endothelial structures and spindle cell formations. The KS cells contained characteristically numerous multivesicular bodies, a large number of tubuloreticular structures and abundant Weibel-Palade bodies in their cytoplasm. Virus particles, 100-120 nm in diameter, were observed budding from the plasma membrane or as free particles already separated from the plasma membrane. Many mature virions manifested a dense cylindrical-shaped core. These virus particles and the human T-cell lymphotropic retroviruses subgroup HTLV-III are ultrastructurally identical. This report is based on recent immunological research.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

The preparation and characterization of lipid vesicles containing esters of sucrose and fatty acids.

Encapsulation and electron microscopy studies have shown that aqueous dispersions of several nonionic emulsifiers with sucrosepalmitatestearate (SPS) structure and cholesterol (Chol) result in synthetic lipid vesicles. This was demonstrated for the commercial emulsifier sucrosepalmitatestearate for the first time. Such vesicles were able to entrap aqueous solutes, for instance the fluorescence marker carboxyfluorescein (CF) for a period of more than 10 weeks with latencies of about 90 per cent. Though SPS/Chol-vesicles tended to flocculate--especially in concentrated solutions--the efflux of entrapped solutes after storage was lower in these vesicles compared with liposomes consisting of natural egg phosphatidylcholine (EPC) and cholesterol.

Carboxylic Acids↗

PubMedDate not supplied

[Melanocytes, Langerhans and Merkel cells in oral epithelium].

The fine structural morphology of melanocytes, Langerhans cells and Merkel cells in the normal dorsal epithelium of the human tongue has been studied by electron microscopy. Melanocytes were regularly found in normal papillary epithelium, even in the absence of clinical signs of pigmentation. The basal epithelial melanocyte contains individual pigment organelles at different stages of maturation and rudimentary half-desmosomes were found between the melanocyte and the basal membrane. The suprabasal Langerhans cells can be identified by their specific organelles and by the lack of tonofilaments and desmosomes. The morphological features of these cells suggest functional relations to cell structures of the keratinocytes and to the epithelial keratinization process. The Merkel cell is characterized by a horizontal orientation in the basal epithelial layer, the development of desmosomal attachments to keratinocytes, the lack of tonofilaments, the typical Merkel cell granules and an associated axon terminal. The observation of Merkel cell granules in relation to the Merkel cell plasmalemma and the morphological similarity of these granules to the monoamine-storing granules in certain types of chromaffin cell system suggest a symbiotic union between the specialized Merkel cell and the associated neurite with a neuroepithelial tactile receptor function. Because of their specific ultrastructure, the Merkel cells are thought to constitute a self-maintaining cell population, independent of keratinocytes and dendritic cells, in the oral epithelium.

Basement Membrane↗

PubMedDate not supplied

[Electron microscopy studies of the oral mucosal epithelium after irradiation with a helium-neon laser].

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Animals↗