PubMed · 10712122
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S N Glick. 2000-03-09. Virtual colonoscopy.. https://pubmed.ncbi.nlm.nih.gov/10712122/
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BACKGROUND: It is common practice for a panendoscopy to be included in the evaluation of patients with mucosal head and neck malignancies. Whether this intervention is efficient or cost-effective has not been established in our patient population. METHODS: Two hundred twenty-four patients with squamous cell carcinoma involving the oral cavity, pharynx, larynx, or neck were evaluated prospectively with panendoscopy and chest x-ray with or without barium swallow. One hundred fifty-four patients had newly diagnosed tumors and 70 were previously diagnosed and currently undergoing symptom-directed investigations. RESULTS: The incidence of synchronous primary tumors was 2.6% (4 of 154); pulmonary, 1.3%; head and neck mucosa, 1.3%; and esophageal, 0%. There was no associated morbidity. CONCLUSIONS: Although there was no associated morbidity, our head and neck oncology group is of the opinion that routine panendoscopy is not warranted. Specific indications for this investigation are discussed.
A surface characterization of barium sulfate particles in aqueous suspensions was carried out in this work. With the aim of predicting the stability conditions of these widely used suspensions, the electrical surface properties of the particles were first studied by electrophoretic mobility determinations. It was found that both H(+) and OH(-) ions can be considered as potential-determining ions for the barium sulfate/water interface. The same conclusion was reached concerning the lattice ions, Ba(2+) (mainly) and SO(4)(2-). It was also found that increasing the concentration of sodium chloride in the dispersion medium can even change the sign of the zeta (zeta) potential: it is suggested that this behavior is an indirect effect provoked by changes in the solubility of barium sulfate with the ionic strength. To compute the van der Waals (LW) attraction between the particles as well as the acid-base contribution to the total energy of interaction, a thermodynamic characterization of the interface was also carried out by measuring the rate of penetration of selected liquids through plugs of the particles. It was found that barium sulfate particles are essentially monopolar in nature; that is, they show electron-donor character as demonstrated by the essentially zero value of the electron-acceptor component of their surface free energy. Pretreatment of the particles with 10(-2) M solutions of BaCl2 and CaCl2 significantly reduced the electron-donor component, whereas both NaCl and Na(2)SO(4) provoked the opposite effect. This result is explained in terms of the acid-base character of the ions added. These data were used to calculate the interaction energy between the particles. The effect of electrolyte concentration on the stability of the suspensions was analyzed on the basis of the dependence with distance of the interaction energy between the particles. Our results suggest that more stable suspensions of barium sulfate are predicted if moderate amounts of SO(4)(2-) ions are added to the dispersion medium.
BACKGROUND: The use of radiographic contrast media in the setting of possible bowel ischemia and potential perforation is known to carry a risk of morbidity and mortality. However, studies of the effect of available contrast media on host immunological defense mechanisms are lacking. We have examined the effect of barium and of two water-soluble contrast agents of differing iodine concentration and osmolality, Conray 30 and Cysto Conray II, on leukocyte phagocytosis. MATERIALS AND METHODS: Blood samples were incubated with the contrast media alone (termed the "resting state"), and in combination with a standard phagocytic challenge (Zymosan polysaccharide extract) and with Staphylococcus epidermidis, Streptococcus faecalis and Escherichia coli, to determine the effect of contrast media upon leukocyte phagocytic response. Incubation with saline was used as control. In the case of barium, the "resting state" and standard challenge experiments were repeated at nine dilutions, ranging from 1:1 to 1:1000. The leukocyte phagocytic response was measured in two ways: CO2 generation (an index of metabolic activity) and chemiluminescence (an index of generation of reactive oxygen species and bacterial killing). RESULTS: Barium, at clinical dilutions, causes a significant increase of baseline "resting state" phagocytic activity, which in turn leads to significant blunting of subsequent response to phagocytic challenge and adversely affects the response to all bacteria tested. There is no baseline activation of leukocytes by the water-soluble media, although there was some inhibition (rather than activation) of leukocyte metabolic activity. The effect of the water-soluble media on bacteria was more complex (although inhibition is minor compared to barium). CONCLUSIONS: Our data demonstrate that barium is a significant activator of phagocytic cells, which results in deactivation of phagocytic response when challenged; these data serve to explain the enhanced adverse effect of barium in cases of fecal peritonitis.