[Parathyroid cyst: case report]. / Cisto de paratireóide: relato de caso.

Parathyroid cysts are very uncommon lesions, with about 200 cases in the literature. Differential diagnosis is difficult, particularly with thyroid mass and symptoms of cervical compression and hyperparathyroidism are described. We present a case in which the diagnosis was intraoperative and discuss the treatment of this unusual disease.

[Incidence of oral cancer profile at a general hospital in Säo Paulo]. / Perfil de incidência do câncer oral em um hospital geral em São Paulo.

Cancer of the oral cavity are 4% of all cancers, being in 8th place in males and 11th in females. The world incidence in male sex is 7.9:100,000 and 2.2:100,000 in females. Squamous cell carcinoma is the most frequent, corresponding to 90-95% of the cases and tongue, lips and floor of the mouth are the most common sites. Fifty-four patients were surgically treated for cancer of the oral cavity in a General Hospital in São Paulo, during last ten years. It occurs more in males (81.5%), the age ranges of 35-97, with mean age of 58.1 years. Smoking was associated in 88.9%, at the time of treatment 50% of the patients had history of disease inferior of 6 months and 42% were T2 and 38% T4. These results agree with international literature and emphasize the importance of preventive aspects of this cancer.

Influence of boundary information on the perception of color.

The integration of color and form to produce a unified percept is a central problem in vision research. We know that the spatial arrangement of colored stimuli influences their detectability. In the gap effect, for example, a small gap between two colored fields enhances their discriminability [Opt. Acta 24, 159 (1977)]. Chromatic thresholds are also reduced when test fields are spatially demarcated. To explore the mechanisms underlying these types of effect, the influence of spatial structure on chromatic sensitivity for gratings was measured. For sine-wave and square-wave gratings modulated in different directions in color space, contrast sensitivity was measured by using a two-alternative forced-choice procedure with a QUEST staircase. Thin lines, of the same orientation as that of the grating, were superimposed on it at half-cycle intervals. The phase of the superimposed lines was varied. For S-cone modulated gratings, dark lines placed at the midpoints between peaks and troughs (90 degrees) increased sensitivity. As the phase of the lines moved toward the peaks (0 degree), their effect on sensitivity declined to zero. A similar but smaller effect was seen for isoluminant L- and M-cone modulated gratings. The superimposed lines always impaired contrast sensitivity for achromatic gratings, especially at a phase of 0 degree. Spatial structure superimposed on gratings can both facilitate and impair contrast sensitivity. In the presence of sharp boundaries, chromatic sensitivity is increased. This effect may depend more on the salience of boundaries, since isoluminant lines superimposed on S-cone modulated gratings and gray lines of similar cone contrast can facilitate detection if they are of sufficient contrast. Achromatic contrast sensitivity is reduced when the boundaries are present. The additional luminance information at the boundaries masks the grating. A simple model in which spatial integration is arrested at the positions of the superimposed lines fits only the isoluminant conditions. For both luminance and chromatic contrast the change in sensitivity depends on phase.

Psychophysical evaluation of gamut mapping techniques using simple rendered images and artificial gamut boundaries.

Using a paired comparison paradigm, various gamut mapping algorithms were evaluated using simple rendered images and artificial gamut boundaries. The test images consisted of simple rendered spheres floating in front of a gray background. Using CIELAB as our device-independent color space, cut-off values for lightness and chroma, based on the statistics of the images, were chosen to reduce the gamuts for the test images. The gamut mapping algorithms consisted of combinations of clipping and mapping the original gamut in linear piecewise segments. Complete color space compression in RGB and CIELAB was also tested. Each of the colored originals (R,G,B,C,M,Y, and Skin) were mapped separately in lightness and chroma. In addition, each algorithm was implemented with saturation (C(*)/L(*)) allowed to vary or retain the same values as in the original image. Pairs of test images with reduced color gamuts were presented to twenty subjects along with the original image. For each pair the subjects chose the test image that better reproduced the original. Rank orders and interval scales of algorithm performance with confidence limits were then derived. Clipping all out-of-gamut colors was the best method for mapping chroma. For lightness mapping at low lightness levels and high lightness levels particular gamut mapping algorithms consistently produced images chosen as most like the original. The choice of device-independent color space may also influence which gamut mapping algorithms are best.

Formation of cytosine arabinoside-5'-triphosphate in different cultured lymphoblastic leukaemic cells with reference to their drug sensitivity.

The accumulation of intracellular cytosine arabinoside-5'-triphosphate (Ara-CTP) is determined in five lymphoblastic cell lines: Molt 4, H9 and three newly established cell lines from paediatric patients, KFB-1, KFB-2, KFT-1. The cell lines KFB-1 and KFB-2 are B-lymphoblastic (B-ALL), the others are T-lymphoblastic leukaemic cells (T-ALL). The Ara-CTP levels were compared with the sensitivity of the cells to Ara-C. The cells were incubated at different concentrations (100 nM-100 microM) of Ara-C for 4 h or incubated for variable times (30 min-11 h) at 0.1, 1 and 10 microM Ara-C to form Ara-CTP. The Ara-CTP-concentrations were measured by high pressure liquid chromatography (HPLC). To determine the sensitivity of the cells to Ara-C, the MTT colorimetric-assay was used. The studies indicate that different B- and T-lymphoblastic leukaemia cell lines accumulate Ara-CTP to a markedly different extent. Ara-CTP plateau levels and sensitivity of the cells to Ara-C correlated well in four of the five cells lines studied.

Surface color naming in dichromats.

In previous experiments, Montag and Boynton [(1987) Vision Research, 27, 2153-2162] found that many dichromats can categorize colors using color naming in fair agreement with color-normal subjects. The contribution of rods to color vision was suspected as underlying this ability. Here we follow up on these experiments by having dichromats name colors under various conditions. When the stimuli are limited to a brief presentation time (60 msec) the dichromats' categorization in the three dimensions of the OSA color space is impaired. Using high light levels so that the rods are saturated does not impair performance. The dichromats named colors during the period of the cone plateau following a rod bleach. Contrary to Montag and Boynton (1987) there was no deficit. These results suggest that an anomalous third cone pigment is responsible for the categorization in three dimensions. It is concluded that the receptors containing the anomalous pigment require greater temporal and spatial summation in order to contribute to the dichromats' color categorization.

Human tritanopia associated with two amino acid substitutions in the blue-sensitive opsin.

Tritanopia is an autosomal dominant genetic disorder of human vision characterize by a selective deficiency of blue spectral sensitivity. The defect is manifested within the retina and could be caused by a deficiency in function or numbers (or both) of blue-sensitive cone photoreceptors. We have used PCR, denaturing gradient gel electrophoresis, and DNA sequencing of amplified exons to detect in four of nine unrelated tritanopic subjects two different point mutations in the gene encoding the blue-sensitive opsin, each leading to an amino acid substitution. Segregation analysis within pedigrees and hybridization of oligonucleotides specific for each allele to DNA samples from control subjects support the hypothesis that these mutations cause tritanopia. These results complete the genetic evidence for the trichromatic theory of human color vision.

Rod influence in dichromatic surface color perception.

Two protanopes, two deuteranopes, and two normal subjects named 424 OSA Uniform Color Scales samples using single-word color terms of their choice under three different experimental conditions. When viewing a stimulus field subtending about 4 deg, the performance of the dichromats revealed a substantial ability to discriminate colors along the red-green axis. When the stimuli were limited to the central fovea, or when rods were excluded with a bleach, dichromats could no longer categorize colors in the red-green dimension. The different conditions did not affect the performance of the normals. The results suggest that rods contribute signals used by dichromats, along with lightness cues, to help discriminate and categorize surface colors.