Transient failure of opening of the lower oesophageal sphincter on upright oesophagrams: radiographic and clinical findings.

The purpose of our study was to determine the frequency, radiographic features, and clinical importance of transient failure of opening of the lower oesophageal sphincter (LOS) on upright double-contrast views of the oesophagus. A computerized search of radiology records identified 16 patients who had transient failure of opening of the LOS on upright views from biphasic oesophagrams or upper gastrointestinal tract examinations using high-density barium but normal opening of the LOS on prone views using low-density barium. The radiographic findings were reviewed and correlated with the clinical and manometric findings. In all cases, barium studies revealed tapered, beaklike narrowing of the distal oesophagus on upright double-contrast views, with a normal-appearing distal oesophagus, normal opening of the LOS, and intact peristalsis on prone single-contrast views. Only seven patients (44%) had dysphagia. Five of these patients had clinical follow-up, and the dysphagia improved or resolved without specific treatment for LOS dysfunction in four. The remaining patient had persistent dysphagia, but this individual had polymyositis as the likely cause for his dysphagia. Manometry revealed incomplete relaxation of the LOS in two patients and normal relaxation in one. Our experience suggests that failure of opening of the LOS may be observed as a transient finding of little clinical importance on upright double-contrast views of the oesophagus using high-density barium, with normal opening of the LOS on prone single-contrast views using low-density barium. It is important to be aware of this finding, so that it is not mistaken for achalasia or other abnormalities of the distal oesophagus.

Reduced dark-adaptation: an indication of lithium's neuronal action in humans.

Although lithium plays a major role in therapy and prophylaxis of affective psychoses, no direct indication of its neuronal action in humans exists. A lithium-induced strong reduction of foveal dark-adaptation was found in healthy volunteers, and a lithium-induced reduction was also measured in patients with affective psychoses. Dark-adaptation measurements apparently offer the opportunity for in vivo monitoring of lithium's CNS effects in humans and may predict lithium's clinical efficacy.

Stain removal from a pigmented silicone maxillofacial elastomer.

The removal of environmental stains from a pigmented maxillofacial elastomer was carried out by solvent extraction under network swelling. Silastic 44210 was pigmented with 11 maxillofacial pigments prior to staining. Samples were stained with lipstick, methylene blue, and disclosing solution. These stains were then removed by solvent extraction with 1,1,1-trichloroethane. Color parameter measurements both before and after staining and after solvent extraction demonstrated the effectiveness of removing these stains by solvent extraction while causing little or no change in the color of the pigmented samples.

Cigarette staining and cleaning of a maxillofacial silicone.

In this study, a maxillofacial silicone elastomer was stained with cigarette smoke. The stain was then removed by solvent extraction using 1,1,1-trichloroethane. The cigarette smoke produced large color changes in the elastomer as measured from spectrophotometric reflectance curves. The solvent was totally effective in removing the cigarette stain without changing the color of the silicone base.

Color stability of new composite restorative materials under accelerated aging.

The color stability of seven commercial composite restorative materials under conditions of accelerated aging was evaluated by reflection spectrophotometry at baseline and 300, 600, and 900 h. During early aging the composites generally became darker, more chromatic, and more opaque. Changes in color of the conventional composites during aging were influenced by erosion of the resin matrices and exposure of filler particles. Color stability of the microfilled composites under the in vitro conditions tested was better than that of the conventional composites and did not appear to be influenced as much by erosion.

Frictional behavior and surface failure of acrylic denture teeth.

The water characteristics of acrylic denture teeth were investigated under single- and double-pass sliding. The response of acrylic teeth to sliding was that of a relatively ductile material. The wear characteristics were affected similarly by environments of water and saliva. The "enamel" surfaces showed more resistance to penetration and were less susceptible to surface damage than the "dentin" surfaces. The effect of the second pass was to increase track width and cause a more severe mode of surface failure.

Reflection spectrophotometry of facial skin.

The color of human skin of 241 whites, blacks, and orientals was measured by reflection spectrophotometry. Among these groups, major differences in luminous reflectance and excitation purity, but not in dominant wavelength, were observed. The twin absorption bands of oxyhemoglobin at 540 and 580 nm were more prominent in whites (particularly females) than in orientals or blacks. Parameters determined for Source A were higher than those for Source C.

Stain removal from a silicone maxillofacial elastomer.

In this study, environmental stains were removed from maxillofacial elastomers by solvent extraction. Silastic 44210, an RTV silicone with proven color and physical property stability, was stained with lipstick, disclosing solution, and methylene blue. These stains were then removed by solvent extraction with each of four chemically dissimilar solvents, namely: toluene, benzene, 1,1,1-trichloroethane, and n-hexane. An additional series of samples was prepared with 11 maxillofacial pigments, not for staining, but for evaluation of pigment stability. Results obtained from spectrophotometric measurements before and after solvent extraction demonstrated the effectiveness of solvent extraction in removing stains, while there was little or no change in the color of the pigments or the base elastomer.

Properties of microfilled and visible light-cured composite resins.

Physical and mechanical properties of four commercial micro-filled composite resins, a visible light-cured composite resin, and a conventional composite resin were investigated. Isocap, Isopast, and Superfil were similar in most properties. Compared with Concise, they had lower values of inorganic filler content and modulus of elasticity and higher values of water sorption, depth of indentation, and linear coefficient of thermal expansion. The properties of Silar were between those of Concise and the other microfilled composite resins. Fotofil had lower values of modulus of elasticity, water sorption, and linear coefficient of thermal expansion than Concise.

Diffusion model of radon exhalation rates.

Radon migration through walls is considered using an effective diffusion model. One and two dimensional models as well as a spherical geometry are compared. It is concluded that either the 1-dimensional or spherical model, both having analytical solution, may be used for practical purposes. Application is made for typical cases in Athens, Greece.

Raman scattering boson peak and differential scanning calorimetry studies of the glass transition in tellurium-zinc oxide glasses.

Raman scattering and differential scanning calorimetry (DSC) measurements have been carried out on four mixed tellurium-zinc oxide (TeO(2))(1 - x)(ZnO)(x) (x = 0.1, 0.2, 0.3, 0.4) glasses under variable temperature, with particular attention being given to the respective glass transition region. From the DSC measurements, the glass transition temperature T(g) has been determined for each glass, showing a monotonous decrease of T(g) with increasing ZnO content. The Raman study is focused on the low-frequency band of the glasses, the so-called boson peak (BP), whose frequency undergoes an abrupt decrease at a temperature T(d) very close to the respective T(g) values obtained by DSC. These results show that the BP is highly sensitive to dynamical effects over the glass transition and provides a means for an equally reliable (to DSC) determination of T(g) in tellurite glasses and other network glasses. The discontinuous temperature dependence of the BP frequency at the glass transition, along with the absence of such a behaviour by the high-frequency Raman bands (due to local atomic vibrations), indicates that marked changes of the medium range order (MRO) occur at T(g) and confirms the correlation between the BP and the MRO of glasses.

Properties of silicone maxillofacial elastomer processed in stone and metal.

1. The effect of mold conditions on the UTS, n, and TS at 200% and 300% elongations, and Shore A hardness was measured for Silastic 44210. 2. There was no difference in n, Shore A hardness, and TS at 200% and 300% elongation between Silastic 44210 samples whether produced in metal or coated stone molds. 3. The highest UTS for Silastic 44210 was demonstrated for samples processed in aluminum molds. The UTS was slightly reduced when coated stone molds were used, and it was considerably reduced with untreated stone molds. It is felt that the slight decrease in UTS with coated stone molds would not compromise the use of stone molds clinically, particularly when ease of processing is considered. 4. Petroleum jelly, silicone spray, and tinfoil substitute were all equally effective in improving the physical properties of the elastomer when processed in a stone mold. These results demonstrate the necessity of using a mold sealant when processing Silastic 44210 in a stone mold.

Inner surface roughness of complete cast crowns made by centrifugal casting machines.

Six variables that could affect the surface roughness of a casting were investigated. The variables were (1) type of alloy, (2) mold temperature, (3) metal casting temperature, (4) casting machine, (5) sandblasting, and (6) location of each section. It was determined that the training portion of a complete cast crown had rougher surfaces than the leading portion. Higher mold and casting temperatures produced rougher castings, and this effect was more pronounced in the case of the base metal alloy. Sandblasting reduced the roughness, but produced scratched surfaces. Sandblasting had a more pronounced affect on the surface roughness of the base metal alloy cast either at a higher mold temperature or metal casting temperature. The morphology and the roughness profile of the original cast surface differed considerably with the type of alloy used.

Effect of in vivo lithium treatment on (-)isoproterenol-stimulated cAMP accumulation in lymphocytes of healthy subjects and patients with affective psychoses.

Lithium treatment inhibited (-)isoproterenol-stimulated cAMP accumulation in lymphocytes of 83% of the normal control subjects investigated. Of the normal control subjects, 17% did not show inhibition of cAMP synthesis after lithium treatment. In one single normal control subject a clear inverse correlation was found between lithium serum concentration and maximal cAMP response. The cAMP levels of six manic-depressive and of four schizoaffective patients receiving lithium treatment did not differ significantly from those of 10 lithium-treated normal subjects. The results obtained in normal subjects seem to support the hypothesis that lithium reduces postsynaptic receptor sensitivity by decreasing cAMP response to agonist stimulation. Treatment outcome, however, does not seem to be exclusively related to a blunted noradrenergic response, since the only patient who did not respond to the treatment had a very low (-)isoproterenol-induced cAMP response after lithium treatment.