Network Analysis: A Systems Framework to Address Grand Challenges in Plant Pathology.

Plant pathology must address a number of challenges, most of which are characterized by complexity. Network analysis offers useful tools for addressing complex systems and an opportunity for synthesis within plant pathology and between it and relevant disciplines such as in the social sciences. We discuss applications of network analysis, which ultimately may be integrated together into more synthetic analyses of how to optimize plant disease management systems. The analysis of microbiome networks and tripartite phytobiome networks of host-vector-pathogen interactions offers promise for identifying biocontrol strategies and anticipating disease emergence. Linking epidemic network analysis with social network analysis will support strategies for sustainable agricultural development and for scaling up solutions for disease management. Statistical tools for evaluating networks, such as Bayesian network analysis and exponential random graph models, have been underused in plant pathology and are promising for informing strategies. We conclude with research priorities for network analysis applications in plant pathology.

MR lesion load and cognitive function in patients with relapsing-remitting multiple sclerosis.

BACKGROUND AND PURPOSE: Multiple sclerosis (MS) is a demyelinating disease most often associated with progressive physical impairment; however, its effects are noted to extend beyond physical disability. Our purpose was to determine the relationship between T2 lesion volume and neurocognitive and physical disability in relapsing-remitting multiple sclerosis. METHODS: We studied a cohort of 19 patients with relapsing-remitting MS. Of this group, there were 15 women and four men from varying socioeconomic backgrounds. This volunteer sample was selected from a larger group of 53 patients with MS in our longitudinal MS study because they had been untreated with any beta-interferon medications, had been followed for at least 12 months, and had a clinical status of relapsing-remitting MS. RESULTS: Of 12 neurocognitive parameters tested, two correlated significantly with lesion loads. The correlation of the Symbol-Digit Modalities test, which analyzes information-processing speed, was significant (P = .0204). The correlation of the fifth trial of the Rey Auditory Verbal Learning test, which tests verbal long-term memory, was also significant (P = .0348). None of the other 10 neurocognitive examinations, however, showed a significant correlation with total lesion volume (Paced Auditory Serial Addition test-1.6, P = .7381; Paced Auditory Serial Addition test-2.0, P = .4180; Controlled Oral Word Association test, P = .8906; Category Fluency test, P = .4423; Bells test, P = .9097; Rey Auditory Verbal Learning test-delay, P = .9843, Rey Auditory Verbal Learning test-recognition, P = .7467; Word Span test, P = .4939; Road Map test, P = 0.4939). The lesion load also did not correlate with the physical disability scales as rated according to the Expanded Disability Status Scale (P = .68) or Ambulation Index (P = .95). CONCLUSION: Our results indicate that T2 lesion volume does not seem to be a robust surrogate marker of neuropsychological impairment in patients with MS. We think that global measurements of parameters that are more specific to the disease process may offer more precise correlation with cognitive dysfunction and other disability parameters.

MR imaging quantitation of gray matter involvement in multiple sclerosis and its correlation with disability measures and neurocognitive testing.

BACKGROUND AND PURPOSE: Multiple sclerosis (MS) is the most common inflammatory disease of the central nervous system and manifests both physical and neurocognitive disabilities. Although predominantly a disease of the white matter, MS is also characterized by lesions in the gray matter. Previous pathologic studies have found that cortical and deep gray matter lesions comprised 5% and 4%, respectively, of total lesions. Using software for lesion detection and quantitation, our study was designed to determine MS involvement in the cortical and deep gray matter and to correlate gray matter lesion load with neurocognitive function and the Kurtzke Expanded Disability Status Scale. METHODS: Using a semiautomated segmentation algorithm that detected and delineated all possible brain MS lesions on MR images, we investigated gray matter lesion volume in 18 patients with untreated relapsing-remitting MS. Cortical and deep gray matter lesions then were correlated with the neurocognitive and physical disability measurements. RESULTS: We found that cortical gray matter lesions comprised approximately 5.7% of the total lesion volume, whereas deep gray matter lesions comprised another 4.6% in this patient cohort. No strong correlations were found between gray matter lesions and disability status or neurocognitive function. CONCLUSION: These results are similar to those found in previous pathologic studies. The cortical lesion load in cases of relapsing-remitting MS, as measured by MR imaging, represents less than 6% of the total lesion volume and does not correlate with disability measures or neurocognitive tests.

Familial multiple sclerosis: volumetric assessment in clinically symptomatic and asymptomatic individuals.

A genetic basis for clustering of multiple sclerosis (MS) cases, based on studies of MS families, has been proposed for decades. Few reports provide detailed neurological as well as neuroradiological findings on these patients. We report total T2-weighted intracranial lesion volumes on members of three familial MS cohorts: a mother and father with conjugal MS with one affected son and a neurologically normal son and daughter, one pair of monozygotic twin sisters with MS, and a female sibling pair with MS. We hypothesized that asymptomatic siblings in a family with two affected parents and another affected child might demonstrate clinically silent T2-weighted lesions; and that monozygotic twins with MS are more likely to express similar T2-weighted lesion volumes than non-twin sibling pairs. We found clinically silent lesions in unaffected children of the symptomatic parent couple, with a significant difference in total T2 lesion volume between these unaffected siblings and their parents, as well as their affected brother. In our other sibling pairs, T2 lesion volumes were similar between the twins and significantly different in the non-twin pair, despite similar levels of clinical functioning as determined by EDSS scoring. These results suggest that foci of demyelination might be expected in clinically normal offspring of parents with MS, possibly reflecting a genetic predisposition to subsequent development of MS.

Trends in contact lens-associated corneal ulcers.

Charts of 320 patients with corneal ulcers seen on the Cornea Service of Wills Eye Hospital from July 1, 1992, to June 30, 1995, were reviewed retrospectively. Of these cases, 96 (30%) were associated with contact lens use. Ulcers in contact lens users accounted for 36% of cases in the last 6 months of 1992 and all of 1993, 20% of cases in 1994, and 29% in the first 6 months of 1995. The contact lenses most commonly associated with ulcers were disposable extended-wear lenses. They were used in 33% of contact lens-associated ulcers in 1992, 27% in 1993, 39% in 1994, and 44% in 1995. Pseudomonas was the predominant organism prior to 1993 (1-4). From 1993 to 1995, however, the number of Pseudomonas ulcers steadily decreased. Two or three Acanthamoeba infections continue to be treated each year. There has been a significant decrease in the number of contact lens-related ulcers treated at our institution compared with previous years (p < 0.01) (3, 4).