An Automated Statistical Technique for Counting Distinct Multiple Sclerosis Lesions

BACKGROUND AND PURPOSE

Lesion load is a common biomarker in multiple sclerosis, yet it has historically shown modest association with clinical outcome. Lesion count, which encapsulates the natural history of lesion formation and is thought to provide complementary information, is difficult to assess in patients with confluent (ie, spatially overlapping) lesions. We introduce a statistical technique for cross-sectionally counting pathologically distinct lesions.

MATERIALS AND METHODS

MR imaging was used to assess the probability of a lesion at each location. The texture of this map was quantified using a novel technique, and clusters resembling the center of a lesion were counted. Validity compared with a criterion standard count was demonstrated in 60 subjects observed longitudinally, and reliability was determined using 14 scans of a clinically stable subject acquired at 7 sites.

RESULTS

The proposed count and the criterion standard count were highly correlated (r = 0.97, P < .001) and not significantly different (t₅₉ = -.83, P = .41), and the variability of the proposed count across repeat scans was equivalent to that of lesion load. After accounting for lesion load and age, lesion count was negatively associated (t₅₈ = -2.73, P < .01) with the Expanded Disability Status Scale. Average lesion size had a higher association with the Expanded Disability Status Scale (r = 0.35, P < .01) than lesion load (r = 0.10, P = .44) or lesion count (r = -.12, P = .36) alone.

CONCLUSIONS

This study introduces a novel technique for counting pathologically distinct lesions using cross-sectional data and demonstrates its ability to recover obscured longitudinal information. The proposed count allows more accurate estimation of lesion size, which correlated more closely with disability scores than either lesion load or lesion count alone.

The Development of Emergency Medicine in South Korea: Academic Productivity in Highly Cited Journals

Introduction

The purpose of this study was to examine the number of publications by South Korean emergency physicians in highly cited journals and the increase in their numbers. It also sought to assess the impact factors of such publications.

Methods

The present study was a retrospective quantitative literature review of the publications by South Korean emergency physicians from 1996 to 2011 in the category of “emergency medicine” in the science edition of Journal Citation Reports 2011. We analysed the total number of articles published by South Korean emergency physicians and their impact factors.

Results

Between 1996 and 2011, the number of South Korean board-certified emergency physicians increased from 51 to 958, and 230 articles were published in 14 highly cited journals. The total impact factor (IF) of the original articles published during that period was 227.86, and the mean IF was 1.93. More than 10 articles had been published annually in the past 5 years in highly cited journals and there were over 400 South Korean board-certified emergency physicians.

Conclusions

Emergency medicine in South Korea started about 20 years ago, but academic productivity, indicated by at least ten articles annually in highly cited journals, was only achieved in the last five years. The mean IF of these articles was similar to that in other highly productive countries. (Hong Kong j.emerg.med. 2014;21:205-212)

Short communication: Variability in milk urea nitrogen and dairy total mixed ration composition in the northeastern United States

The main objective of this survey was to examine variability in milk urea nitrogen (MUN) for Dairy Herd Improvement Association (DHIA) herds in the northeastern United States (the Northeast), examine trends in dairy cow diet composition, and determine potential relationships for MUN and diet composition. Trends in milk fat and protein concentrations, milk yield, days in milk on test day, and lactation number of the cows were also evaluated. The data set for the survey included 10,839,461 DHIA dairy cow records from 2004 to 2015 for 13 states (CT, DE, MA, MD, ME, NH, NJ, NY, PA, RI, VA, VT, and WV) and was retrieved from Dairy Records Management Systems (Raleigh, NC). Average (across states and years) milk yield, milk fat, and milk protein were 31.6 ± 0.24 kg/d, 3.85 ± 0.021%, and 3.13 ± 0.013%, respectively. No obvious trends were observed for milk fat or protein content, but milk yield steadily increased during the survey period. Milk urea N concentration averaged 13.3 ± 0.13 mg/dL, with no obvious or consistent trends. Examination of variability in dairy feed cost and all milk price for the Northeast indicated that high MUN generally coincided with high feed cost and high milk price. For the diet composition survey, 9,707 records of total mixed ration (TMR) analyses, unrelated to the milk composition data set, from the Cumberland Valley Analytical Service (Maugansville, MD) database were examined. Concentration of TMR crude protein (CP) decreased from 17.1% in 2007 to 16.4% in 2015, but there was not an obvious trend in soluble protein concentration. Concentration of TMR neutral detergent fiber (NDF) and 24-h in vitro NDF degradability declined steadily during the survey period and was accompanied by a steady increase in TMR starch concentration. Examination of these unrelated data sets revealed lack of correlation between MUN and diet chemical composition. Thus, we conclude that individual cow MUN in Northeast dairy herds fluctuated between 2004 and 2015. It appeared that MUN followed variability in feed cost; however, ration feed ingredient data were not available to better define the reasons for the variations in MUN.

Performance of the Minto model for the target-controlled infusion of remifentanil during cardiopulmonary bypass

We studied the predictive performance of the Minto pharmacokinetic model during cardiopulmonary bypass in patients undergoing cardiac surgery. Patients received remifentanil target-controlled infusion using the Minto model during total intravenous anaesthesia with propofol. From 56 patients, 275 arterial blood samples were drawn before, during and after bypass to determine the plasma concentration of remifentanil, and the predicted concentrations were recorded at each time. For pooled data, the median prediction error and median absolute prediction error were 21.3% and 21.8%, respectively, and 22.1% and 22.3% during bypass. Both were 148.4% during hypothermic circulatory arrest and measured concentrations were more than three times greater than predicted (26.9 (17.0) vs. 7.1 (1.6) ng.ml^-1 ). The Minto model showed considerable bias but overall acceptable precision during bypass. The target concentration of remifentanil should be reduced when using the Minto model during hypothermic circulatory arrest.

Volumetric Analysis from a Harmonized Multisite Brain MRI Study of a Single Subject with Multiple Sclerosis

BACKGROUND AND PURPOSE

MR imaging can be used to measure structural changes in the brains of individuals with multiple sclerosis and is essential for diagnosis, longitudinal monitoring, and therapy evaluation. The North American Imaging in Multiple Sclerosis Cooperative steering committee developed a uniform high-resolution 3T MR imaging protocol relevant to the quantification of cerebral lesions and atrophy and implemented it at 7 sites across the United States. To assess intersite variability in scan data, we imaged a volunteer with relapsing-remitting MS with a scan-rescan at each site.

MATERIALS AND METHODS

All imaging was acquired on Siemens scanners (4 Skyra, 2 Tim Trio, and 1 Verio). Expert segmentations were manually obtained for T1-hypointense and T2 (FLAIR) hyperintense lesions. Several automated lesion-detection and whole-brain, cortical, and deep gray matter volumetric pipelines were applied. Statistical analyses were conducted to assess variability across sites, as well as systematic biases in the volumetric measurements that were site-related.

RESULTS

Systematic biases due to site differences in expert-traced lesion measurements were significant (P < .01 for both T1 and T2 lesion volumes), with site explaining >90% of the variation (range, 13.0-16.4 mL in T1 and 15.9-20.1 mL in T2) in lesion volumes. Site also explained >80% of the variation in most automated volumetric measurements. Output measures clustered according to scanner models, with similar results from the Skyra versus the other 2 units.

CONCLUSIONS

Even in multicenter studies with consistent scanner field strength and manufacturer after protocol harmonization, systematic differences can lead to severe biases in volumetric analyses.

Host-mediated effects of phytonutrients in ruminants: A review

Plants produce an extensive array of organic compounds derived from secondary metabolism that may be useful in animal nutrition because of their chemical makeup. These plant-derived bioactive compounds, also referred to as phytonutrients (PN) or phytobiotics, have been shown to express antimicrobial activities against a wide range of bacteria, yeast, and fungi and have been investigated as rumen modifiers in ruminant nutrition. Studies have reported that PN may inhibit deamination of AA and methanogenesis in the rumen and shift fermentation toward propionate and butyrate. Most of the experiments, however, have been conducted in vitro, and responses have been highly variable and inconsistent in animal experiments. In addition, some studies have reported that PN had positive effects on productivity, although rumen fermentation was not affected. Other than antimicrobial effects in the gut, PN are known to bind specific receptors expressed in neurons, intestines, and other cells and exhibit related physiological effects in nonruminants. The receptor-mediated effects include immune responses, oxidative stress, and insulin secretion and activity. Some PN, due to their phenolic nature, are likely less susceptible to microbial degradation in the rumen and may exhibit activities postruminally, similar to their mode of action in nonruminant species. This opens a new area of research in ruminants, including effects of PN on the animal's immune system, postruminal nutrient use, and animal physiology. Although limited, studies with ruminants provide first evidence of PN's regulatory effects on the host responses. For example, PN were reported to regulate immune cells related to adaptive and innate immunity in challenged or nonchallenged dairy cows. Supplementation of PN reduced oxidative stress by decreasing lipid peroxidation and increasing endogenous antioxidants in ruminants. Additionally, insulin secretion and sensitivity were reportedly regulated by PN in dairy cows. The regulatory effects of PN on immunity may be beneficial for immune suppression and inflammation in dairy cows. In addition, PN could positively affect energy partitioning for milk production through their effects on insulin secretion and sensitivity. Further research is needed to elucidate the effect and mode of action of PN on immune function and animal energetics.