A horizontal, fluorophore-enhanced, repetitive extragenic palindromic-PCR (rep-PCR) DNA fingerprinting technique (HFERP) was developed and evaluated as a means to differentiate human from animal sources of Escherichia coli. Box A1R primers and PCR were used to generate 2,466 rep-PCR and 1,531 HFERP DNA fingerprints from E. coli strains isolated from fecal material from known human and 12 animal sources: dogs, cats, horses, deer, geese, ducks, chickens, turkeys, cows, pigs, goats, and sheep. HFERP DNA fingerprinting reduced within-gel grouping of DNA fingerprints and improved alignment of DNA fingerprints between gels, relative to that achieved using rep-PCR DNA fingerprinting. Jackknife analysis of the complete rep-PCR DNA fingerprint library, done using Pearson's product-moment correlation coefficient, indicated that animal and human isolates were assigned to the correct source groups with an 82.2% average rate of correct classification. However, when only unique isolates were examined, isolates from a single animal having a unique DNA fingerprint, Jackknife analysis showed that isolates were assigned to the correct source groups with a 60.5% average rate of correct classification. The percentages of correctly classified isolates were about 15 and 17% greater for rep-PCR and HFERP, respectively, when analyses were done using the curve-based Pearson's product-moment correlation coefficient, rather than the band-based Jaccard algorithm. Rarefaction analysis indicated that, despite the relatively large size of the known-source database, genetic diversity in E. coli was very great and is most likely accounting for our inability to correctly classify many environmental E. coli isolates. Our data indicate that removal of duplicate genotypes within DNA fingerprint libraries, increased database size, proper methods of statistical analysis, and correct alignment of band data within and between gels improve the accuracy of microbial source tracking methods.

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IntroductionIn patients with Alzheimer's disease (AD) and mild cognitive impairment, structural changes in the retina (i.e., reduced thicknesses of the ganglion cell and retinal nerve fiber layers and inclusion bodies that appear to contain beta-amyloid protein [Ab]) have been previously reported. We sought to explore whether anatomic retinal changes are detectable in the preclinical stage of AD.MethodsA cross-sectional study (as part of an ongoing longitudinal cohort study) involving 63 cognitively normal adults, all of whom have a parent with AD and subjective memory complaints. We compared neocortical amyloid aggregation (florbetapir PET imaging) to retinal spectral domain optical coherence tomography (SD-OCT) markers of possible disease burden. Retinal biomarkers, including the number and surface area of retinal inclusion bodies and the thickness of retinal neuronal layers, were compared across groups with high vs. low neocortical beta-amyloid load.ResultsThe surface area of inclusion bodies increased as a function of cortical amyloid burden. Additionally, there was a trend toward a selective volume increase in the inner plexiform layer (IPL; a layer rich in cholinergic activity) of the retina in Aβ+ relative to Aβ− participants, and IPL volume was correlated with the surface area of retinal inclusion bodies.DiscussionThese initial results suggest that retinal imaging may be a potential cost-effective and noninvasive technique that can be used to identify those at-risk for AD. Layer-specific changes in the IPL and their association with surface area of inclusion bodies are discussed as a possible reflection of early inflammatory processes associated with cholinergic disruption and concurrent Ab accumulation in the neocortex.

Introduction We conducted a 27-month longitudinal study of mid-life adults with preclinical Alzheimer's disease (AD), using spectral domain optical coherence tomography to compare changes in volume and thickness in all retinal neuronal layers to those of age-matched healthy control subjects. Methods Fifty-six older adults (mean age = 65.36 years) with multiple risk factors for AD completed spectral domain optical coherence tomography retinal imaging and cognitive testing at baseline. Twenty-seven months later, they completed the same examinations and an 18 F-florbetapir positron emission tomography imaging study. Results Compared to healthy control subjects, those in the preclinical stage of AD showed a significant decrease in macular retinal nerve fiber layer (mRNFL) volume, over a 27-month follow-up interval period, as well as a decrease in outer nuclear layer and inner plexiform layer volumes and thickness in the inferior quadrant. However, only the mRNFL volume was linearly related to neocortical positron emission tomography amyloid standardized uptake value ratio after controlling for any main effects of age ( R 2 = 0.103; ρ = 0.017). Furthermore, the magnitude of mRNFL volume reduction was significantly correlated with performance on a task of participants' abilities to efficiently integrate visual and auditory speech information (McGurk effect). Discussion We observed a decrease in mRNFL, outer nuclear layer, and inner plexiform layer volumes, in preclinical AD relative to controls. Moreover, the largely myelinated axonal loss in the RNFL is related to increased neocortical amyloid-β accumulation after controlling for age. Volume loss in the RNFL, during the preclinical stage, is not related to performance on measures of episodic memory or problem solving. However, this retinal change does appear to be modestly related to relative decrements in performance on a measure of audiovisual integration efficiency that has been recently advanced as a possible early cognitive marker of mild cognitive impairment.

To assess optical coherence tomography in differentiating optic disc edema (ODE) due to papilledema and other optic neuropathies from optic nerve head drusen (ONHD). Methods: Optical coherence tomographic images from 60 subjects (20 with ODE, 20 with ONHD, and 20 control subjects) were assessed qualitatively and quantitatively. Qualitative criteria for ODE included an elevated optic nerve head with smooth internal contour and subretinal hyporeflective space (SHYPS) with recumbent "lazy V" pattern. Optic nerve head drusen displayed a "lumpybumpy" internal optic nerve contour and a rapid decline in SHYPS thickness. Quantitative comparisons included retinal nerve fiber layer and SHYPS thickness. Results: Optical coherence tomography differentiated ODE from ONHD qualitatively (sensitivity, 63%; speci-ficity, 63%) and quantitatively (sensitivity, 80%; specificity, 90%). Respective differences in mean retinal nerve fiber layer thickness between ODE and ONHD were significant (P Ͻ .002) superiorly (206.8 vs 121.7 µm), nasally (176.3 vs 78.6 µm), inferiorly (247.2 vs 153.8 µm), and temporally (180.0 vs 85.5 µm). Respective differences in mean SHYPS thickness between ODE and ONHD were significant (PϽ .001) at radii of 0.75 mm (512.1 vs 274.4 µm), 1.5 mm (291.4 vs 103.0 µm), and 2.0 mm (145.5 vs 60.7 µm). Conclusion: Optical coherence tomography can differentiate ODE from ONHD, particularly when the nasal retinal nerve fiber layer and SHYPS thickness at the 2.0-mm radius are greater than 86 µm and 127 µm, respectively.

Microbial source tracking (MST) results, obtained using identical sample sets and pulsed field gel electrophoresis (PFGE), repetitive element PCR (rep-PCR) and ribotyping techniques were compared. These methods were performed by six investigators in analysis of duplicate, blind sets of water samples spiked with feces from five possible sources (sewage, human, dog, cow and seagull). Investigators were provided with samples of the fecal material used to inoculate the water samples for host origin database construction. All methods correctly identified the dominant source in the majority of the samples. Modifications of some of these methods correctly identified the dominant sources in over 90% of the samples; however, false positive rates were as high as 57%. The high false positive rates appeared to be indirectly proportional to the levels of stringency applied in pattern analysis. All the methods produced useful data but the results highlighted the need to modify and optimize these methods in order to minimize sources of error.

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The survival of 78 patients with resected non-small cell lung cancer entered in prospective, randomized investigational trials is compared to that of a population-based group of control patients not included in such trials. The survival of trial patients is significantly better than that of controls (P less than 0.001). This survival advantage for trial participants is most apparent among late Stage I patients, and is observed after matching for known prognostic factors (i.e., primary tumor size, nodal status, tumor histology) and after adjusting in the analysis for age, sex, and the administration of radiation therapy. Several explanations for the improved outcome for trial patients are explored, including differences in preoperative evaluation, staging, surgical technique, placebo effects, and patient motivation. These results suggest the possibility that inclusion in these controlled cancer trials may have had an inherent advantage for all participants.