Rose Nolen-Walston

Cellular kinetics and modeling of bronchioalveolar stem cell response during lung regeneration.

Organ regeneration in mammals is hypothesized to require a functional pool of stem or progenitor cells, but the role of these cells in lung regeneration is unknown. Whereas postnatal regeneration of alveolar tissue has been attributed to type II alveolar epithelial cells (AECII), we reasoned that bronchioalveolar stem cells (BASCs) have the potential to contribute substantially to this process. To test this hypothesis, unilateral pneumonectomy (PNX) was performed on adult female C57/BL6 mice to stimulate compensatory lung regrowth. The density of BASCs and AECII, and morphometric and physiological measurements, were recorded on days 1, 3, 7, 14, 28, and 45 after surgery. Vital capacity was restored by day 7 after PNX. BASC numbers increased by day 3, peaked to 220% of controls (P<0.05) by day 14, and then returned to baseline after active lung regrowth was complete, whereas AECII cell densities increased to 124% of baseline (N/S). Proliferation studies revealed significant BrdU uptake in BASCs and AECII within the first 7 days after PNX. Quantitative analysis using a systems biology model was used to evaluate the potential contribution of BASCs and AECII. The model demonstrated that BASC proliferation and differentiation contributes between 0 and 25% of compensatory alveolar epithelial (type I and II cell) regrowth, demonstrating that regeneration requires a substantial contribution from AECII. The observed cell kinetic profiles can be reconciled using a dual-compartment (BASC and AECII) proliferation model assuming a linear hierarchy of BASCs, AECII, and AECI cells to achieve lung regrowth.

Multinodular pulmonary fibrosis in five horses

CASE DESCRIPTION 5 horses were evaluated because of decreased appetite, weight loss, fever, cough, tachypnea, and respiratory distress. CLINICAL FINDINGS Tachycardia, tachypnea, increased respiratory effort, lethargy, fever, poor body condition, and nasal discharge were detected in various combinations on initial physical examination. Evaluation of the lower portion of the respiratory tract via radiography and ultrasonography revealed a severe nodular interstitial pattern. Histologic examination of lung tissue revealed interstitial expansion of alveolar parenchyma with collagen, intraluminal accumulation of neutrophils and macrophages within the alveoli, and occasional intranuclear inclusion bodies within alveolar macrophages. Equine herpesvirus type 5 was detected in samples of lung tissue, bronchoalveolar lavage fluid, or both via polymerase chain reaction assay in all cases. A diagnosis of equine multinodular pulmonary fibrosis (EMPF) was established. TREATMENT AND OUTCOME Horses were provided supportive treatment and were administered a variety of medications including corticosteroids and acyclovir. Two horses survived and returned to their previous level of activity. Three horses were euthanized because of either deterioration of clinical condition (n=2) or failure to improve within 4 weeks of initiation of treatment (1). CLINICAL RELEVANCE EMPF should be considered as a differential diagnosis for adult horses with interstitial pneumonia and should be suspected on the basis of characteristic radiographic, ultrasonographic, and histopathologic findings. Equine herpesvirus type 5 is found in association with EMPF; although the exact pathogenic role this virus plays in EMPF is unknown, equine herpesvirus type 5 may be an etiologic agent or cofactor in the development of EMPF.

Reproducibility of airway responsiveness in horses using flowmetric plethysmography and histamine bronchoprovocation.

BACKGROUND Inflammatory airway disease has a high prevalence in horses, but is often a diagnostic challenge. Flowmetric plethysmography and histamine bronchoprovocation (FP/HBP) is a simple and effective tool for diagnosis, but reproducibility of these measurements made over time has not been established. HYPOTHESIS We hypothesize that the measurement of airway responsiveness in horses using FP/HBP is consistent over both short and long periods of time. ANIMALS Twenty-nine healthy adult horses from 2 university herds. METHODS In this prospective experimental study, airway responsiveness was determined in each horse at day 0 (baseline [BL]) with FP/ HBP, using PC35 (provocative concentration of histamine needed to increase Delta(flow) by 35%) as a measure of airway responsiveness. Each horse was re-tested 1-4 weeks after BL (short-term [ST]) and again at 3-12 months after BL (long-term [LT]). RESULTS In the ST period, 23/27 (85%) of the horses had a PC35 that was within 1 doubling concentration of histamine of their BL value, with a mean change of 0.52 doubling concentrations (95% CI 0.26-0.79, range 0-2.06). For the LT data, 19/26 (73%) of horses were within 1 doubling concentration of their BL value, with a mean change of 0.81 doubling concentrations (95% CI 0.45-1.17, range 0.14-3.10). There was no significant difference in reproducibility between the 2 groups of subjects. CONCLUSIONS AND CLINICAL IMPORTANCE Repeated measurements of airway responsiveness obtained with FP/HBP show acceptable reproducibility over time periods up to a year. However, caution must be used when testing horses when ambient air temperature is low.

Effect of prolonged administration of clenbuterol on airway reactivity and sweating in horses with inflammatory airway disease

OBJECTIVE To determine whether prolonged administration of clenbuterol results in tachyphylaxis, specifically regarding its bronchoprotective properties and effect on sweating in horses. ANIMALS 8 Thoroughbreds with inflammatory airway disease. PROCEDURES In a crossover design, horses received clenbuterol (0.8 μg/kg, p.o., q 12 h) or placebo for 21 days, with a washout period of ≥ 30 days between the 2 treatments. Airway reactivity was evaluated by use of flowmetric plethysmography and histamine broncho-provocation before (day 0; baseline) and every 7 days after the start of treatment. Sweat function was evaluated via response to epinephrine administered ID before and every 10 days after the start of treatment. RESULTS The concentration of histamine required to increase total airway obstruction by 35% (PC35) was significantly reduced during treatment with clenbuterol (mean change, 11.5 mg/mL), compared with during administration of the placebo (mean change, -1.56 mg/mL), with a peak effect at 14 days. Tachyphylaxis was evident by day 21, with 7 of 8 horses having a PC35 below the baseline value (mean change, -0.48 mg/mL), which returned to baseline values during the washout period. No effect of clenbuterol was seen in sweat response to epinephrine administration. CONCLUSIONS AND CLINICAL RELEVANCE Clenbuterol initially reduced airway sensitivity to inhaled histamine, but tachyphylaxis that resulted in increased airway reactivity was evident by day 21. Although no effects on sweating were detected, the technique may not have been sensitive enough to identify subtle changes. Prolonged administration of clenbuterol likely results in a clinically important reduction in its bronchodilatory effects.

Effect of sample storage on blood crossmatching in horses

BACKGROUND Blood samples banked for up to 1 month are typically used to perform pretransfusion testing in humans and small animals, but this has not been validated using blood from horses. HYPOTHESIS Compatibility of equine blood samples is repeatable using fresh samples, and reproducible using donor blood samples stored for up to 4 weeks. ANIMALS Six healthy adult horses. METHODS Randomized, blinded experimental study. Immunologic compatibility of the blood of all horses was assessed using a major and minor saline agglutination and hemolysin crossmatch using blood samples refrigerated for 0-4 weeks and fresh blood from the same horses. Crossmatch results were scored and then compared to identify changes of compatibility in each of the 4 tests. In addition, repeatability of the crossmatch technique itself was assessed by performing 6 iterations of this procedure in immediate succession with fresh blood from 3 horses. RESULTS No significant difference in crossmatch results was found using fresh blood (P = .39-1.00). Reproducibility was poor using blood stored for 1-4 weeks, especially in tests using stored erythrocytes (major antigen crossmatches), with significant differences from baseline at all weeks (P < .05); 13 of these differences were positive, indicating poorer compatibility. CONCLUSIONS AND CLINICAL IMPORTANCE Equine blood crossmatching is repeatable using fresh blood, although decreased apparent compatibility after storage makes exclusion of compatible donors more likely than mistaken administration of incompatible blood. These data suggest that fresh samples should be collected from potential donors before crossmatching equine blood.

Clinical and Pathological Features of Pheochromocytoma in the Horse: A Multi-Center Retrospective Study of 37 Cases (2007–2014)

Background Pheochromocytoma is the most common adrenal medullary neoplasm of domestic animals, but it is rare in horses. Antemortem diagnosis in horses is difficult, with clinical signs often being vague or non‐specific. Objective The objective of this study was to describe the clinical, laboratory, and pathologic findings of pheochromocytoma in horses. Animals Thirty‐seven horses diagnosed with pheochromocytoma based on postmortem examination from 2007 to 2014. Methods Retrospective case series. Results Pheochromocytoma was identified in 37/4094 horses during postmortem examination. Clinical signs consistent with pheochromocytoma had been observed antemortem in only 7 cases, with the remainder being incidental findings. Colic was the most common presenting complaint (13 of 37 cases) and tachycardia was noted in 95% of cases (median heart rate of 86 bpm in clinical cases). Hyperlactatemia (median, 4.9 mmol/L) and hyperglycemia (median, 184 mg/dL) were the most common clinicopathologic abnormalities. Hemoperitoneum caused by rupture of pheochromocytoma was noted in 4/7 clinical cases. Concurrent endocrine abnormalities (eg, thyroid adenoma, adrenal hyperplasia, pituitary pars intermedia hyperplasia or adenoma, parathyroid C‐cell carcinoma) were found in 27/37 horses, with 8/37 horses having lesions consistent with multiple endocrine neoplasia syndrome as described in humans. Conclusions Pheochromocytoma was diagnosed in 0.95% of horses presented for necropsy. The majority of these were incidental findings, but pheochromocytoma was thought to contribute to clinical findings in 19% of cases, and multiple endocrine neoplasms were commonly seen. Usually an incidental finding at necropsy, pheochromocytoma may cause acute death from intraperitoneal exsanguination and should be considered in horses presenting with colic, tachycardia, and hemoperitoneum.

Detection of two equine trisomies using SNP-CGH

Chromosomal aberrations in the horse are known to cause congenital abnormalities, embryonic loss, and infertility. While diagnosed mainly by karyotyping and FISH in the horse, the use of SNP array comparative genome hybridization (SNP-CGH) is becoming increasingly common in human diagnostics. Normalized probe intensities and allelic ratios are used to detect changes in copy number genome-wide. Two horses with suspected chromosomal abnormalities and six horses with FISH-confirmed aberrant karyotypes were chosen for genotyping on the Equine SNP50 array. Karyotyping of the first horse indicated mosaicism for an additional small, acrocentric chromosome, although the identity of the chromosome was unclear. The second case displayed a similar phenotype to human disease caused by a gene deletion and so was chosen for SNP-CGH due to the ability to detect changes at higher resolutions than those achieved with conventional karyotyping. The results of SNP-CGH analysis for the six horses with known chromosomal aberrations agreed completely with previous karyotype and FISH analysis. The first undiagnosed case showed a pattern of altered allelic ratios without a noticeable shift in overall intensity for chromosome 27, consistent with a mosaic trisomy. The second case displayed a more drastic change in both values for chromosome 30, consistent with a complete trisomy. These results indicate that SNP-CGH is a viable method for detection of chromosomal aneuploidies in the horse.

Plasma Peak and Trough Gentamicin Concentrations in Hospitalized Horses Receiving Intravenously Administered Gentamicin

Background Gentamicin is an aminoglycoside antimicrobial commonly used in horses at 6.6 mg/kg IV once daily. Therapeutic drug monitoring (TDM) can confirm desired peak concentration is reached for common bacterial isolates, and detect toxicosis associated with high trough values. Objectives Determine the relationship between gentamicin dose and plasma concentration in hospitalized horses, and identify a starting dose range to achieve peaks > 32 μg/mL. Animals Sixty‐five horses (2002–2010) receiving once‐daily gentamicin with TDM performed (N = 99 sets). Methods Retrospective study. Data from hospitalized horses including weight, dose, plasma peak, and trough gentamicin concentration, creatinine concentrations and presence of focal or systemic disease were collected from medical records. Peak concentrations measured 25–35 minutes after administration were included (N = 77). Data were divided into low (<7.7 mg/kg), medium (7.7–9.7 mg/kg) and high (>9.7 mg/kg) dose groups, and were grouped by the horse having focal or systemic disease. Results Peak concentrations resulting from doses ≥7.7 mg/kg were 5.74 μg/mL (SE 2.1 μg/mL) greater than peaks from doses <7.7 mg/kg (P = .007). Peak concentrations was 3.6 times more likely to be >32 μg/mL if dose was ≥7.7 mg/kg (P = .04). There were no significant effects of dose on trough or creatinine concentration. At a given dose, horses with focal disease had higher peaks than those with systemic disease (P = .039). Conclusions and Clinical Importance These data suggest gentamicin dosage should be individually determined in horses using TDM, but support an initial once‐daily dose of 7.7–9.7 mg/kg IV to achieve peaks >32 μg/mL and trough concentrations <2 μg/mL. Further studies evaluating the safety of doses >6.6 mg/kg are required.

Flow rates of large animal fluid delivery systems used for high‐volume crystalloid resuscitation

OBJECTIVES Large animal species in states of shock can require particularly high flow rates for volume resuscitation and the ability to deliver adequate volumes rapidly may be a rate-limiting step. The objective of this study was to determine the maximum flow rates of common combinations of IV catheter, extension set, and fluid administration sets. SETTINGS University veterinary teaching hospital. DESIGN In vitro experimental study. INTERVENTIONS Maximum flow rates were measured using combinations of 4 IV catheters (3 14-Ga and a single 10-Ga), 2 IV catheter extension sets (small bore and large bore), and 2 types of fluid administration sets (standard 2-lead large animal coiled IV set and nonpressurized 4-lead arthroscopic irrigation set). The catheter, extension sets, and administration sets were arranged in 16 configurations, and flow rates measured in triplicate using tap water flowing into an open receptacle. MEASUREMENTS AND MAIN RESULTS Flow rates ranged from 7.4 L/h with an over-the-wire 14-Ga catheter, small-bore extension, and coil set, to 51.2 L/h using a 10-Ga catheter, no extension, and arthroscopic irrigation set. There was an increase of 1.3-8.9% in flow rates between the large- versus small-bore extension sets. Crystalloid delivery in vivo to an adult horse was 21% slower (9.1 L/h versus 11.5 L/h) than the corresponding in vitro measurement. CONCLUSIONS Extremely high flow rates can be achieved in vitro using large-bore catheters and delivery systems, although the clinical necessity for rates >50 L/h has not been determined. The use of large-bore extension sets resulted in only a minimal increase in flow rate.Objectives Large animal species in states of shock can require particularly high flow rates for volume resuscitation and the ability to deliver adequate volumes rapidly may be a rate-limiting step. The objective of this study was to determine the maximum flow rates of common combinations of IV catheter, extension set, and fluid administration sets. Settings University veterinary teaching hospital. Design In vitro experimental study. Interventions Maximum flow rates were measured using combinations of 4 IV catheters (3 14-Ga and a single 10-Ga), 2 IV catheter extension sets (small bore and large bore), and 2 types of fluid administration sets (standard 2-lead large animal coiled IV set and nonpressurized 4-lead arthroscopic irrigation set). The catheter, extension sets, and administration sets were arranged in 16 configurations, and flow rates measured in triplicate using tap water flowing into an open receptacle. Measurements and Main Results Flow rates ranged from 7.4 L/h with an over-the-wire 14-Ga catheter, small-bore extension, and coil set, to 51.2 L/h using a 10-Ga catheter, no extension, and arthroscopic irrigation set. There was an increase of 1.3–8.9% in flow rates between the large- versus small-bore extension sets. Crystalloid delivery in vivo to an adult horse was 21% slower (9.1 L/h versus 11.5 L/h) than the corresponding in vitro measurement. Conclusions Extremely high flow rates can be achieved in vitro using large-bore catheters and delivery systems, although the clinical necessity for rates >50 L/h has not been determined. The use of large-bore extension sets resulted in only a minimal increase in flow rate.

Effect of clenbuterol on tracheal mucociliary transport in horses undergoing simulated long-distance transportation

BACKGROUND Pneumonia is observed in horses after long-distance transportation in association with confinement of head position leading to reduction in tracheal mucociliary clearance rate (TMCR). HYPOTHESIS/OBJECTIVES Clenbuterol, a beta-2 agonist shown to increase TMCR in the horse, will ameliorate the effects of a fixed elevated head position on large airway contamination and inflammation in a model of long-distance transportation model. ANIMALS Six adult horses. METHODS A cross-over designed prospective study. Horses were maintained with a fixed elevated head position for 48 hours to simulate long-distance transport, and treated with clenbuterol (0.8 μg/kg PO q12h) or a placebo starting 12 hours before simulated transportation. TMCR was measured using a charcoal clearance technique. Data were collected at baseline and 48 hours, and included TMCR, tracheal wash cytology and quantitative culture, rectal temperature, CBC, fibrinogen, and serum TNFα, IL-10, and IL-2 levels. There was a 18-21 day washout between study arms, and data were analyzed using regression analysis and Wilcoxon rank-sum tests. RESULTS Tracheal mucociliary clearance rate was significantly decreased after transportation in both treatment (P = .002) and placebo (P = .03) groups. There was a significant effect of treatment on TMCR, with the treatment group showing half the reduction in TMCR compared with the placebo group (P = .002). Other significant differences between before- and after-transportation samples occurred for serum fibrinogen, peripheral eosinophil count, quantitative culture, tracheal bacteria, and degenerate neutrophils, though no treatment effect was found. CONCLUSIONS AND CLINICAL IMPORTANCE Treatment with clenbuterol modestly attenuates the deleterious effects of this long-distance transportation model on tracheal mucociliary clearance.