Microbial diversity and resistance to copper in metal-contaminated lake sediment.

Contamination of habitats with heavy metals has become a worldwide problem. We describe herein the analysis of lake sediment contaminated with high concentrations of copper as a consequence of mine milling disposal over a 100-year period. Copper concentrations in the sediment were found to vary with depth and ranged from 200 to 5500 ppm. Analysis of the microbial community with T-RFLP identified a minimum of 20 operational taxonomic units (OTU). T-RFLP analysis along a depth profile detected as many as nine shared OTUs across 15 centimeters, suggesting a conservation of community structure over this range. Only two genera, Arthrobacter and Ralstonia, were detected among 50 aerobic copper-resistant isolates cultivated on R2A, one of which (Ralstonia sp.) was characterized by the sequestration of copper, identified by electron diffraction scanning, in growing colonies. Scanning electron microscopy showed changes to the outer envelope of the cells when grown in the presence of copper. The copper-resistant Ralstonia isolates were also resistant to Ni, Cd, and Zn, showing two patterns of phenotypic resistant to these three metals in which either resistance to Zn or Ni was expressed in an isolate but never both.

Geochemistry of Bulgarian soils in villages affected and not affected by Balkan endemic nephropathy: a pilot study.

Balkan endemic nephropathy (BEN) is a chronic tubulointerstitial disease whose mosaic-like distribution throughout the Balkans has not changed significantly since its initial description. In this study, we explored the hypothesis that the occurrence of BEN is linked with the environmental geochemistry of villages. Soil samples were collected from BEN and non-BEN villages in the Vratza region of Bulgaria. Samples were digested in nitric acid and analyzed for 22 elements by hexapole, inductively coupled plasma, and mass spectrometry. Selected results are that: 1) absolute concentrations from both types of villages were not enriched above "background" concentrations; and 2) copper, molybdenum, lead, and cadmium concentrations were higher in BEN than in non-BEN soils, while selenium concentrations were lower. Although geochemical differences between BEN and non-BEN villages were found, not all differences were statistically significant, in part due to a limited number of samples.

The SKILL Card test in optic neuritis: experience of the Optic Neuritis Treatment Trial. Smith-Kettlewell Institute Low Luminance. Optic Neuritis Study Group.

OBJECTIVES: To assess the value of the Smith-Kettlewell Institute Low Luminance (SKILL) Card test, designed to measure vision at reduced contrast and luminance, among patients with previous optic neuritis. MATERIALS AND METHODS: The SKILL Card test was administered to 295 patients participating in the Optic Neuritis Treatment Trial (ONTT) follow-up study, concurrent with measurement of visual acuity, visual field, contrast sensitivity, and color vision. Health-related quality of life (HRQL) was also assessed in a subset of patients using the National Eye Institute Visual Function Questionnaire and an ONTT-developed questionnaire. RESULTS: The SKILL Card difference score (high-contrast acuity score minus low-contrast acuity score) was only weakly associated with the other measures of vision function (rs absolute range, 0.05-0.31) and with the HRQL measures (rs absolute range, 0.02-0.15). In contrast, the light and dark component scores of the SKILL Card test had higher associations with the other vision measures (rs absolute range, 0.27-0.54) and with the HRQL measures (rs absolute range, 0.10-0.40). CONCLUSIONS: The SKILL Card difference score is not a meaningful measure for patients with optic neuritis; however, the test appears to have clinical usefulness as a method to measure high-contrast and low-contrast acuity.

Interaction between HLA-DR2 and abnormal brain MRI in optic neuritis and early MS. Optic Neuritis Study Group.

The association of the human leukocyte antigen (HLA)-DR2 allele with brain MRI signal abnormalities and with the development of MS was assessed in 178 patients enrolled in the Optic Neuritis Treatment Trial. HLA haplotype DR2 was present in 85 (48%) of the 178 patients. Its presence was associated with increased odds of probable or definite MS at 5 years (odds ratio, 1.92; 95% confidence interval, 1.01 to 3.67; p = 0.04). The association was most apparent among patients with signal abnormalities on baseline brain MRI.

The National Eye Institute Visual Function Questionnaire: experience of the ONTT. Optic Neuritis Treatment Trial.

PURPOSE: To describe the health-related quality of life, measured with the National Eye Institute Visual Function Questionnaire (NEI-VFQ), of patients several years after the onset of optic neuritis, according to their neurologic and visual status; to assess the relationship between the NEI-VFQ subscales and clinical measures of visual function; and to assess the internal consistency reliability of the NEI-VFQ subscales. METHODS: The NEI-VFQ was administered to 244 patients 5 to 8 years after treatment for an episode of acute optic neuritis as part of the Optic Neuritis Treatment Trial. Visual acuity, visual field, contrast sensitivity, and color vision were measured at the same time as questionnaire completion. RESULTS: The NEI-VFQ scores generally were lower than those reported for a disease-free group. Reported dysfunction was greater when multiple sclerosis was present and when visual acuity was abnormal, supporting the construct validity of the NEI-VFQ. Rank correlations between the NEI-VFQ subscales and clinical measures of visual function were moderate at best. Internal consistency reliability was generally high for most of the NEI-VFQ subscales. CONCLUSIONS: These findings add support to the use of the NEI-VFQ as a valuable measure of self-reported visual impairment.

Comparative evaluation of image segmentation methods for volume quantitation in SPECT.

A wide variety of image segmentation techniques have been proposed for the measurement of organ or lesion volumes in SPECT images. Evaluation of the relative performance of the various methods is difficult due to wide variations in system response characteristics, size, shape, and contrast of the imaged objects, and image acquisition and processing techniques. Selected image segmentation methods for volume quantitation in SPECT were applied to a set of simulated SPECT images containing objects ranging in volume from 1.8 to 113.1 cc. The specific segmentation methods included: (1) operator drawn regions of interest, (2) count-based methods, (3) three levels of fixed thresholds, (4) an adaptive threshold (GLH method), (5) a two-dimensional (2-D) edge detection method, and (6) a three-dimensional (3-D) edge detection method. In general, the 3-D edge detection method required minimal operator intervention while providing the most accurate and consistent estimates of object volume across changes in object contrast and size.

SPECT volume quantitation: influence of spatial resolution, source size and shape, and voxel size.

A number of factors influence the accuracy of estimation of source volume with single-photon emission computed tomography (SPECT) imaging. This study investigated the role of a number of factors including system spatial resolution (which includes the influence of low-pass filters applied to suppress noise), source size and shape, and voxel size in determining volume. A rectangular parallelepiped (bar), a right cylinder, and a sphere were mathematically modeled as being imaged with a SPECT system by calculating the three-dimensional (3-D) convolution of them with symmetric Gaussian functions of 20 different full widths at half maximums (FWHM's). The resulting activity profiles were analyzed to determine the location of the edges as a function of the source size relative to the FWHM of the system. The edge definition criteria studied were (1) the location of the 50% count threshold and (2) the maximum in the local gradient. In addition, the threshold which yielded the correct edge location was also determined. A nonstationary computer simulation of SPECT imaging, based on the serial model of the system transfer function, was used to test the predictions of the mathematical model and investigate the influence of (1) voxel size and sampling with a discrete array of voxels; (2) attenuation; (3) scatter; (4) variable spatial resolution; (5) low-pass filtering; and (6) noise. The mathematical model predicted that both the 50% threshold and the maximum in the local gradient methods of estimating edge location would show either an under- or overestimate of source volume depending on both the ratio of source diameter to system FWHM and the source shape.(ABSTRACT TRUNCATED AT 250 WORDS)