Julia B. Montgomery

Meta-analysis of the effect of oral selenium supplementation on milk selenium concentration in cattle

Soils in many regions of the world have a low Se content. Consequently, forages and crops grown on these soils may provide inadequate dietary Se for humans and grazing animals. Selenium supplementation has been used to enhance Se status and milk Se concentration, but results conflict. Milk Se concentration appears to be a useful indicator of animal and herd Se status, and reflects the responsiveness to supplementation. A systematic review and meta-analysis were carried out to summarize all available scientific evidence for the effect of oral Se supplementation on milk Se concentration in cattle. The literature search was based on electronic and nonelectronic databases. Fixed- and random-effects models of meta-analysis were used, and a meta-regression was carried out to evaluate heterogeneity among studies. Random-effects meta-analysis was performed on 42 studies published between 1977 and 2007. Oral Se supplementation resulted in an average increase in milk Se content of 0.16 (95% confidence interval: 0.117, 0.207) micromol/L, with a significant heterogeneity among studies. Weak publication bias was evident, but it did not change the average effect. The continent where the study was performed, Se source, Se dose, and the interaction between source and dose explained 71% of the between-study variance. On average, American cows supplemented with Se yeast (e.g., 6 mg/h per day) had greater milk Se concentrations (approximately 0.37 micromol/L) 75 d after the beginning of supplementation when compared with those supplemented with inorganic forms of Se. This information provides a basis for tailoring daily animal requirements and for enhancing the Se intake of consumers of dairy products.

Remote lung injury after experimental intestinal ischemia-reperfusion in horses.

Ischemia followed by reperfusion leads to release of toxic molecules into the circulation, and these molecules may cause injury in remote organs such as the lung. Horses commonly suffer from episodes of intestinal ischemia-reperfusion (IR) due to intestinal twisting/strangulation followed by repair. Because there is no evidence of lung injury associated with IR in horses, we designed a study to characterize the intestinal IR-associated lung inflammation and determine the effect of lidocaine on lung inflammation in IR horses. Lung tissues were collected from non-anesthetized (n=4) and anesthetized (n=4) control horses and horses (n=12) after 70 minutes of ischemia followed by 60 minutes of reperfusion. Horses in IR groups received Lactated Ringers Solution (LRS; n=6) or lidocaine (n=6) intravenously. Control lungs had normal histology but lungs from IR horses showed moderate accumulation of neutrophils in blood vessels and airways. We found increased staining for TLR4, IL-8, TLR9, and von Willebrand factor (vWF) along with aggregates of vWF-positive platelets in lung vessels of IR horses compared to the controls. Lung TNFα was significantly increased in IR horses compared to the control horses (P<0.05). Neutrophil numbers, but not MPO concentrations, were significantly lower, while macrophage numbers were higher in the IR group receiving lidocaine compared to the LRS horses (P<0.05). We conclude that intestinal IR leads to remote lung injury characterized by recruitment of inflammatory cells and expression of inflammatory molecules in horses, and lidocaine may ameliorate lung inflammation following intestinal IR.

Morphometric Examination of the Equine Adult and Foal Lung

To understand the mechanisms of airway inflammation associated with equine diseases such as Rhodococcus equi infection, we must identify baseline “normal” structural characteristics of the horse lung. To develop a detailed understanding of the morphology of the horse lung, we adapted and applied stereological methods to the lungs from healthy adult horses (N = 4) and 1‐day (N = 5) and 30‐day (N = 5) old foals. The left lung was fixed in situ by intrabronchial instillation of glutaraldehyde/paraformaldehyde fixative at 25 cm H2O column and sampled using a fractionator design followed by embedding in glycol methacrylate. The lung was characterized into parenchyma and non‐parenchyma, where median parenchymal density was 81.0% in 1‐day‐old foals, 84.4% in 30‐day‐old foals and 93.7% in adult lungs. The median volume density of alveolar airspace per lung was 45.9% in 1‐day‐old, 55.5% in 30‐day and 66.9% in adult horse lungs. The median alveolar surface area increased with age, from 205.3 m2, 258.2 m2, and 629.9 m2 in 1‐day‐old foals, 30‐day‐old foals, and adults, respectively. While the median alveolar surface density decreased with age, the mean linear intercept (mean free distance within acinar airspaces) increased with age. Alveolar surface area was greater than endothelial surface area within each lung. The ratio between alveolar and endothelial surface density remains unchanged with age. The median endothelium surface area was 106.2 m2 in 1‐day, 147.5 m2 in 30‐day, and 430 m2 in adult lungs. The data suggest the foal lung is functionally developed and postnatal lung development and remodelling is driven by alveolar expansion paralleled with angiogenesis. Anat Rec, 297:1950–1962, 2014.

Tumor necrosis factor-alpha protein concentrations in bronchoalveolar lavage fluid from healthy horses and horses with severe equine asthma

The objective of this study was to determine if TNF-α protein concentration differs in bronchoalveolar lavage fluid (BALF) obtained from healthy horses, horses with naturally occurring exacerbations of severe equine asthma and horses in remission from severe equine asthma. Tumor necrosis factor-alpha (TNF- α) protein concentrations were determined in BALF by commercial equine ELISA. Horses with naturally occurring exacerbation of severe equine asthma were found to have significantly lower BALF TNF-α protein concentrations than healthy horses (p = 0.0026). There was no significant difference in BALF TNF-α concentration between horses in exacerbation and remission from disease, but there was a decrease in median TNF-α concentration between healthy horses and horses with clinical exacerbation of severe equine asthma. These findings suggest, that similar to human asthma, the role of TNF-α in chronic lower airway inflammation of horses may differ between disease phenotypes and disease state. Furthermore, the method with which TNF-α is measured (mRNA expression vs. protein concentration) may affect results when studying the role of TNF-α in horses with severe equine asthma.