Tritan color-vision deficiency is an autosomal dominant disorder associated with mutations in the short-wavelength-sensitive- (S-) cone-pigment gene. An unexplained feature of the disorder is that individuals with the same mutation manifest different degrees of deficiency. To date, it has not been possible to examine whether any loss of S-cone function is accompanied by physical disruption in the cone mosaic. Two related tritan subjects with the same novel mutation in their S-cone-opsin gene, but different degrees of deficiency, were examined. Adaptive optics was used to obtain high-resolution retinal images, which revealed distinctly different S-cone mosaics consistent with their discrepant phenotypes. In addition, a significant disruption in the regularity of the overall cone mosaic was observed in the subject completely lacking S-cone function. These results taken together with other recent findings from molecular genetics indicate that, with rare exceptions, tritan deficiency is progressive in nature.

In this study, we investigated the effects of 192 IgG saporin injections into the medial septal area (MSA), or nucleus basalis magnocellularis (NBM), and combined injections into the MSA and NBM, on water maze and radial arm maze performance in the male rat. The results of the present study reveal a dissociation between the effects of 192 IgG saporin injections into the basal forebrain on the performance of two tasks of spatial learning in the rat. Bilateral injections of 192 IgG saporin into the NBM, MSA or combined MSA/NBM failed to disrupt water maze performance when compared to controls. In contrast, injections of 192 IgG saporin into the MSA, NBM or MSA/NBM induced mild impairments on a radial arm maze task. Overall, the disruption of spatial learning observed in this study was, however, relatively mild compared to deficits in spatial learning reported using less selective lesions of the cholinergic basal forebrain. Consequently, the results of this study suggest that a selective reduction in cholinergic transmission in the basal forebrain is, by itself, insufficient to account for the functional impairments observed in spatial learning in the rat. Although our data do support the use of 192 IgG saporin as a selective cholinergic toxin in the basal forebrain, they further suggests that assessment of spatial learning in the rat following 192 IgG saporin lesions of the basal forebrain in combination with lesions to other neurotransmitter systems, may be a more viable approach to the elucidation of the neuropathological mechanisms that are associated with the cognitive deficits seen in Alzheimer's disease.

We studied paired bronchoalveolar lavage (BAL) in patients with sepsis-associated acute respiratory distress syndrome (ARDS). Patients were evaluated at one institution and underwent bronchoscopy with BAL within 48 h of the onset of ARDS. Patients were restudied with bronchoscopy and BAL after 4 d of treatment. Fifty-eight patients were initially studied, with 44 patients having follow-up bronchoscopy after 4 d. The overall 30-d survival for the ARDS group was 60%. In the initial lavage, there was no difference in the neutrophils between the survivors and nonsurvivors (survivors: 59 [0-98]%; Median [Range]; nonsurvivors: 55 [0-92]%). The follow-up lavage demonstrated a significant drop in the neutrophils for the survivors (36 [4-89]%, p < 0.002) which was not seen for the nonsurvivors (70 [26-95]%). Initial IL-8 concentrations in the BAL fluid were not significantly different between the two groups. In the follow-up lavage, there was a significant fall for the IL-8 concentrations for the survivors but not the nonsurvivors. We conclude that neutrophil influx in ARDS may rapidly resolve within a week of the onset of ARDS. The resolution of neutrophils was associated with a good prognosis.

Many previous studies have shown that the relative number of long-wavelength-selective (L) versus medium-wavelength-selective (M) cones in the eye influences spectral sensitivity revealed perceptually. Here, we hypothesize that the L:M cone ratio should also influence red/green chromatic contrast sensitivity. To test this, in each subject we derived an estimate of L:M ratio based on her red/green equiluminance settings (obtained with heterochromatic flicker photometry), and measured both red/green chromatic and luminance contrast sensitivity at different spatial and temporal frequencies. Factor analysis was applied to the data in order to reveal covariance between conditions. As expected, chromatic and luminance contrast sensitivity were found to be independent of one another, and no relationship was observed between L:M ratio and luminance contrast sensitivity. However, a significant relationship was observed between L:M ratio and chromatic contrast sensitivity, wherein subjects possessing the most symmetrical L:M cone ratios (i.e., near 1:1) appear to possess the relatively greatest chromatic contrast sensitivity. This relationship can be accounted for by a simple model based on the notion of random L- and M-cone inputs to the center and surround receptive fields of chromatic (L-M) mechanisms.

In order to investigate the mechanisms underlying green/red equiluminance matches in human observers and their relationship to mechanisms subserving luminance and/or chromatic (green/red) contrast sensitivity, we tested 21 human subjects along these dimensions at 16 different spatial and temporal frequencies (spatial frequency, 0.25-2 c/deg; temporal frequency, 2-16 Hz) and applied factor analysis to extract mechanisms underlying the data set. The results from our factor analysis revealed separate sources of variability for green/red equiluminance, luminance sensitivity and chromatic sensitivity, thus suggesting separate mechanisms underlying each of the three main conditions. When factor analysis was applied separately to green/red equiluminance data, two temporally-tuned factors were revealed (factor 1, 2-4 Hz; factor 2, 8-16 Hz), suggesting the existence of separate mechanisms underlying equiluminance settings at low versus high temporal frequencies. In addition, although the three main conditions remained separate in our factor analysis of the entire data set, our correlation matrix nonetheless revealed systematic correlations between equiluminance settings and luminance sensitivity at high temporal frequencies, and between equiluminance settings and chromatic sensitivity at low temporal frequencies. Taken together, these data suggest that the high temporal frequency factor underlying green/red equiluminance is governed predominantly by luminance mechanisms, while the low temporal frequency factor receives contribution from chromatic mechanisms.

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