Item-Score Reliability as a Selection Tool in Test Construction

This study investigates the usefulness of item-score reliability as a criterion for item selection in test construction. Methods MS, λ6, and CA were investigated as item-assessment methods in item selection and compared to the corrected item-total correlation, which was used as a benchmark. An ideal ordering to add items to the test (bottom-up procedure) or omit items from the test (top-down procedure) was defined based on the population test-score reliability. The orderings the four item-assessment methods produced in samples were compared to the ideal ordering, and the degree of resemblance was expressed by means of Kendall's τ. To investigate the concordance of the orderings across 1,000 replicated samples, Kendall's W was computed for each item-assessment method. The results showed that for both the bottom-up and the top-down procedures, item-assessment method CA and the corrected item-total correlation most closely resembled the ideal ordering. Generally, all item assessment methods resembled the ideal ordering better, and concordance of the orderings was greater, for larger sample sizes, and greater variance of the item discrimination parameters

Excursion of the Rotator Cuff Under the Acromion

Nine fresh-frozen, human cadaveric shoulders were el evated in the scapular plane in two different humeral rotations by applying forces along action lines of rotator cuff and deltoid muscles. Stereophotogrammetry deter mined possible regions of subacromial contact using a proximity criterion; radiographs measured acromio humeral interval and position of greater tuberosity. Con tact starts at the anterolateral edge of the acromion at 0° of elevation; it shifts medially with arm elevation. On the humeral surface, contact shifts from proximal to dis tal on the supraspinatus tendon with arm elevation. When external rotation is decreased, distal and poste rior shift in contact is noted. Acromial undersurface and rotator cuff tendons are in closest proximity between 60° and 120° of elevation; contact was consistently more pronounced for Type III acromions. Mean acro miohumeral interval was 11.1 mm at 0° of elevation and decreased to 5.7 mm at 90°, when greater tuberosity was closest to the acromion. Radiographs show bone- to-bone relationship; stereophotogrammetry assesses contact on soft tissues of the subacromial space. Con tact centers on the supraspinatus insertion, suggesting altered excursion of the greater tuberosity may initially damage this rotator cuff region. Conditions limiting ex ternal rotation or elevation may also increase rotator cuff compression. Marked increase in contact with Type III acromions supports the role of anterior acromioplasty when clinically indicated, usually in older patients with primary impingement.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67283/2/10.1177_036354659402200609.pd

Hyperlactatemia After Intracranial Tumor Surgery Does Not Affect 6-Month Survival: A Retrospective Case Series

BACKGROUND: Patients undergoing neurosurgery frequently exhibit hyperlactatemia. The aim of this study was to identify factors associated with hyperlactatemia and assess how hyperlactatemia impacts survival and hospital length of stay after intracranial tumor surgery. MATERIALS AND METHODS: This retrospective cohort study included 496 adult patients that underwent surgery between January 1, 2014 and December 31, 2015. We evaluated patient characteristics, surgery characteristics, pH, lactate, and blood glucose from blood samples collected on admission to the high-dependency unit and the morning after surgery, and 6-month outcome data. RESULTS: Hyperlactatemia (>2.0 mmol/L) occurred in >50% of patients, but only 7.7% had acidosis. Postoperative hyperlactatemia was not correlated with 6-month survival (P=0.987), but was correlated with (median [interquartile range]) longer hospital stays (6 [4 to 8.5] d vs. 5 [4 to 8] d; P=0.006), longer surgery duration (4:53 [4:01 to 6:18

Adaptation of Akkermansia muciniphila to the Oxic-Anoxic Interface of the Mucus Layer

Akkermansia muciniphila colonizes the mucus layer of the gastrointestinal tract, where the organism can be exposed to the oxygen that diffuses from epithelial cells. To understand how A. muciniphila is able to survive and grow at this oxic-anoxic interface, its oxygen tolerance and response and reduction capacities were studied. A. muciniphila was found to be oxygen tolerant. On top of this, under aerated conditions, A. muciniphila showed significant oxygen reduction capacities and its growth rate and yield were increased compared to those seen under strict anaerobic conditions. Transcriptome analysis revealed an initial oxygen stress response upon exposure to oxygen. Thereafter, genes related to respiration were expressed, including those coding for the cytochrome bd complex, which can function as a terminal oxidase. The functionality of A. muciniphila cytochrome bd genes was proven by successfully complementing cytochrome-deficient Escherichia coli strain ECOM4. We conclude that A. muciniphila can use oxygen when it is present at nanomolar concentrations. IMPORTANCE This article explains how Akkermansia muciniphila, previously described as a strictly anaerobic bacterium, is able to tolerate and even benefit from low levels of oxygen. Interestingly, we measured growth enhancement of A. muciniphila and changes in metabolism as a result of the oxygen exposure. In this article, we discuss similarities and differences of this oxygen-responsive mechanism with respect to those of other intestinal anaerobic isolates. Taken together, we think that these are valuable data that indicate how anaerobic intestinal colonizing bacteria can exploit low levels of oxygen present in the mucus layer and that our results have direct relevance for applicability, as addition of low oxygen concentrations could benefit the in vitro growth of certain anaerobic organisms.Peer reviewe