Haptoglobin Quantitation in Serum Samples from Clinically Normal and Clinically Abnormal Horses

Haptoglobin (HP) is a common minor to moderate acute-phase protein in mammals. It has been described as increasing under a variety of conditions in horses, with the use of different assay methods. The goal of the current study was to provide updated information regarding this biomarker by using a commonly available automated assay. In the present study, reference intervals for HP were generated using 43 serum samples from clinically normal horses. The reference interval was determined via the robust method as 0.29-2.26 mg/ml. A statistically significant 3.3-fold mean increase was observed in HP levels from a clinically abnormal group of horses (n = 33). A weak but significant correlation was found between total white blood cell count and HP levels (r = 0.37, P < .05). A significantly higher level of HP expression was observed in samples acquired from patients whose clinical signs lasted for 7 days or longer than from those whose signs were 4 days or less.     

Comparison of Insulin-Induced Digital Vessel Ring Responses of Laminitic and Clinically Healthy Horses

Hyperinsulinemia leads to insulin resistance of blood vessels and interferes with circulation of laminae of the equine foot. The objective of the study was to compare the digital vessel responses of clinically healthy and laminitic horses with and without experimental induction of insulin resistance. Vessel segments (artery and vein) collected after euthanasia were cut into 3-mm wide rings and were prepared in tissue baths containing Tyrode solution for response studies. Two rings of each vessel type from each horse were used as nonresistant, and two were made insulin resistant. Insulin resistance was induced by incubating the rings with 10-μM bath concentration of insulin. Then, all rings were contracted with phenylephrine (5 μM). When the contraction reached a plateau, insulin (10 μM) was added, and the response monitored for 30 minutes. The response to insulin was calculated as a percentage of the phenylephrine response. The results showed that the responses of the nonresistant rings differed significantly between the groups. However, when all rings were made insulin resistant, the significance between the groups disappeared. In the laminitic group, responses of resistant and nonresistant rings did not differ, whereas in the healthy group, the vessel responses differed significantly. In all experiments, arterial and venous rings followed the same pattern, but the magnitudes were greater in arterial rings. The findings suggest that the vessel responses to insulin are altered in laminitis which could be due to insulin resistance.     

Glucocorticoid Receptor Density and Binding Affinity in Healthy Horses and Horses with Systemic Inflammatory Response Syndrome

Background

Dysregulation of the hypothalamic‐pituitary‐adrenal (HPA) axis occurs in horses with systemic inflammatory response syndrome (SIRS). Peripheral resistance to glucocorticoids has not been investigated in horses.

Objective

To determine if glucocorticoid receptor (GR) function in horses can be measured using flow cytometry, and to use this information to evaluate HPA axis dynamics.

Animals

Eleven healthy adult horses in parts 1 and 2. Ten horses with SIRS and 10 age and sex matched controls in part 3.

Methods

Flow cytometry was used to evaluate GR density and binding affinity (BA) in 3 healthy horses in part 1. In part 2, exogenous ACTH was administered to eight healthy horses. Their cortisol response and GR properties were measured. In part 3, CBC, serum biochemistry, cortisol and ACTH, and GR properties were compared between controls without SIRS (n = 10) and horses with SIRS (n = 10), and between survivors and nonsurvivors (n = 4 and n = 6 respectively).

Results

Flow cytometry can be used to measure GR properties in equine PBMCs. No correlation was observed between plasma cortisol concentration and GR density or BA in healthy horses (r = −0.145, P = .428 and r = 0.046, P = .802 respectively). Nonsurvivors with SIRS had significantly decreased GR BA (P = .008). Horses with triglyceride concentration > 28.5 mg/dL had increased odds of nonsurvival (OR=117; 95% CI, 1.94–7,060). GR BA <35.79% was associated with nonsurvival (OR = 30.33; 95% CI, 0.96–960.5).

Conclusions and Clinical Importance

Tissue resistance to glucocorticoids contributes to HPA axis dysfunction in adult horses with SIRS. These horses might benefit from treatment with exogenous glucocorticoids.     

运输对伊犁马肌肉损伤和氧化应激的影响

试验旨在研究运输对伊犁马肌肉损伤和氧化应激的影响。选取体重相近的5匹24月龄的伊犁母马,环境适应7 d后开展运输试验,其运输过程中禁食禁水,运输总路程约为400 km,运输时间为8 h。分别于运输0（T1）、4（T2）、8（T3）和卸车后12 h （T4）采集马颈静脉血,分离血清,进行相关生理生化指标的测定。结果显示,与T1相比,肌肉损伤生化标志物肌红蛋白（MYO）和肌钙蛋白（cTnT）在T2时刻显著上升（P<0.05）,T3和T4时刻极显著上升（P<0.01）;乳酸脱氢酶（LDH）在T3时刻显著上升（P<0.05）;炎症反应生化标志物C反应蛋白（CRP）和白细胞介素-6（IL-6）在T2、T3和T4时刻极显著上升（P<0.01）;皮质醇（COR）在T2和T3时刻极显著上升（P<0.01）,在T4时刻显著上升（P<0.05）;总抗氧化能力（T-AOC）、谷胱甘肽过氧化物酶（GSH-Px）和超氧化物歧化酶（SOD）在T2、T3和T4时刻极显著下降（P<0.01）;过氧化氢酶（CAT）在T3和T4时刻显著下降（P<0.05）;活性氧（ROS）在T2和T4时刻显著上升（P<0.05）,在T3时刻极显著上升（P<0.01）;丙二醛（MDA）在T3和T4时刻极显著上升（P<0.01）。因此,运输8 h导致了伊犁马肌肉损伤和氧化应激反应的发生,其不良影响在卸车后12 h内不能消除。     

Form of Vitamin E Supplementation Affects Oxidative and Inflammatory Response in Exercising Horses

Vitamin E is an essential antioxidant that may benefit athletes by reducing oxidative stress and influencing cytokine expression. Supplements can be derived from natural or manufactured synthetic sources. This study aimed to determine (1) if supplemental vitamin E is beneficial to exercising horses and (2) if there is a benefit of natural versus synthetic vitamin E. After 2 weeks on the control diet (vitamin E–deficient grain and hay), 18 horses were divided into three groups and fed the control diet plus (1) 1000 IU/d synthetic α-tocopherol (SYN-L), (2) 4000 IU/d synthetic α-tocopherol (SYN-H), or (3) 4000 IU/d RRR-α-tocopherol (natural source [NAT]). On day 7, horses began a 6-week training protocol, with standard exercise tests (SETs) performed before and after the 6-week protocol. Venous blood samples were collected on days 0, 7, 29, and 49. Horses fed NAT had higher α-tocopherol (P < .05) at post-SET1 through post-SET2. Plasma thiobarbituric acid–reactive substance levels were lower in NAT versus SYN-L horses after SET2 (P = .02). Serum aspartate aminotransferase was lower after exercise in NAT horses versus SYN-L and SYN-H (P = .02), and less reduction in stride duration was seen after exercise in NAT as compared with SYN-L and SYN-H (P = .02). Gene expression of tumor necrosis factor α was lower in NAT compared with SYN-H (P = .01) but not SYN-L. In conclusion, feeding higher levels of natural vitamin E source resulted in higher serum α-tocopherol levels as well as some improvement in oxidative and inflammatory response and improved functional outcomes in response to an exercise test.     

Adiposity,Plasma Insulin,Leptin, Lipids,and Oxidative Stress in Mature Light Breed Horses

Background

Increased blood insulin levels are associated with an increased risk of pasture‐associated laminitis in equids.

Objective

To determine the relationship between plasma insulin, leptin, and lipid levels, and measures of oxidative stress with adiposity in mature light breed horses.

Animals

300 randomly selected light breed horses, aged 4–20 years.

Methods

A random sample of horses (140 mares, 151 geldings, and 9 stallions) was drawn from the VMRCVM Equine Field Service practice client list. Evaluations occurred June 15 – August 15, 2006, with all sampling performed between 0600 and 1200 hours. Concentrate feed was withheld for at least 10 hours before sampling. Plasma was analyzed for insulin, glucose, leptin, triglycerides, nonesterified fatty acids, and measures of oxidative stress. Body condition score was determined as the average of 2 independent investigators.

Results

Overconditioned and obese horses had higher plasma insulin (P < .001) and leptin (P < .01) levels than optimally conditioned horses. Obese horses had higher triglyceride levels (P = .006) and lower red blood cell gluthathione peroxidase activities (P = .001) than optimally conditioned horses.

Conclusions and Clinical Importance

Maintaining horses at a BCS <7 might be important for decreasing the risk of pasture‐associated laminitis.     

热应激条件下机体发生氧化应激的机制

热应激是指机体在高温条件下对热暴露所做出的非特异性生理反应的总和。有研究表明热应激会引起机体氧化还原平衡紊乱,发生氧化应激,损伤细胞和组织,从而影响机体的生长发育及健康状况。热应激一直都是国内外研究的热点,随着全球气温的上升,热应激问题将会更加突出,本文就热应激条件下氧化应激发生的机制作一综述,以期为后续的相关研究提供参考。     

Clinical Feasibility and Airway Deposition of Nebulized Voriconazole in Healthy Horses

Voriconazole (VRC) is a potential treatment for pneumomycosis in horses. The objectives of this study were to determine if the delivery of Vfend using a Flexineb nebulizer produced clinically significant [VRC] in lower airways. The hypothesis was that [VRC] after delivery by nebulization would be greater in the pulmonary epithelial lining fluid than plasma. A secondary objective was to determine [VRC] in upper airways through the collection of nasopharyngeal wash (NPW) samples. Voriconazole solution [Vfend-6.25 mg/mL, 100 (n = 2), 200 (n = 3), 500 (n = 1) mg] was nebulized once in 6 healthy geldings. Clinical responses, duration of nebulization, and [VRC] at various time points (up to 8 hours) in plasma, bronchoalveolar lavage fluid (BALF) supernatant and cell pellet, and NPW samples were recorded. Voriconazole (Vfend-6.25 mg/mL, 200 mg) was nebulized in 5 additional, healthy geldings, and [VRC] was measured in NPW samples pre- and postnebulization at time points up to 8 hours. The antifungal activity of BALF and NPW samples was determined using agar disk diffusion. Concentrations of voriconazole were below detection in plasma, BALF supernatant, and cell pellets for all time points and doses except the BALF cell pellet (0.4 μg/g) immediately after nebulization of 500 mg. For 5 horses, administered 200 mg of Vfend, mean [VCR] in NPW at the end of nebulization and 1, 6, and 8 hours postnebulization were: 30.8 ± 29, 1.0 ± 0.84, 0.2 ± 0.19, and 0.34 ± 0.67 μg/mL, respectively. Only NPW samples obtained immediately postnebulization showed antifungal activity. A nebulized Vfend solution is not recommended for the treatment of pneumomycosis in horses.     

繁殖母羊的氧化应激和氧化损伤研究

本试验旨在探究不同生殖阶段、胎次繁殖母羊的氧化应激及氧化损伤状态。试验1选取体重、体况相近的2~3胎空怀期、妊娠期(30、60、120 d)、分娩及哺乳期(21 d)的崇明白山羊各5只;试验2选取后备、1胎、2~3胎、4~5胎、6胎及以上的崇明白山羊母羊各5只。分别采集血样,测定血清自由基代谢指标[皮质醇、过氧化氢(H2O2)含量]、抗氧化指标[总抗氧化能力(T-AOC)、谷胱甘肽过氧化物酶(GSH-Px)和超氧化物歧化酶(SOD)活性]、氧化损伤指标[丙二醛(MDA)、8-异前列腺素-F2α(8-ISO-PGF2α)、8-羟基脱氧鸟苷(8-OHDG)、蛋白质羰基化(PC)含量]。结果表明:试验1,从空怀期至哺乳期,血清皮质醇、H2O2含量呈先上升后降低的趋势,在分娩时达最高值,较空怀期显著提高(P0.05);血清T-AOC、SOD活性逐渐增强,且哺乳期21 d较空怀期显著提高(P0.05);血清MDA、8-ISO-PGF2α、PC含量先增加后趋于平稳,且在分娩时达最高,较空怀期显著提高(P0.05),血清8-OHDG含量逐渐增加,哺乳期21 d达到最高,较空怀期显著提高(P0.05)。试验2,随着母羊胎次的增加,血清中皮质醇含量无显著变化(P0.05),4~5胎、6胎及以上血清H2O2含量显著高于其他胎次(P0.05);血清TAOC无显著变化(P0.05),血清SOD及GSH-Px活性逐级递减,6胎及以上较后备母羊下降显著(P0.05);血清MDA、8-ISO-PGF2α、8-OHDG和PC含量逐渐增加,6胎及以上显著高于其他胎次(P0.05)。综上所述,伴随着妊娠的进行,母羊体内的自由基代谢逐渐增强,与此同时,体内的抗氧化水平也相应提高以维持氧化-抗氧化体系平衡,但在妊娠后期至哺乳期激增的活性氧自由基破坏了自由基稳衡体系,导致氧化应激和氧化损伤;随着母羊胎次的增加,抗氧化能力逐渐减弱,高胎次母羊氧化损伤严重。     

动物氧化应激与免疫的研究进展

氧化应激是对动物生产造成巨大经济损失的常见问题之一,它是机体自由基生成增加或(和)清除能力降低,引起机体氧化系统和抗氧化系统紊乱,导致自由基在体内积累而引起的氧化损伤过程。然而,机体抗氧化系统与免疫系统密不可分,其中,核转录因子-κB(NF-κB)信号通路是联系2个系统的重要途径。目前,应用外源抗氧化剂改善动物健康和提高肉制品品质的研究较多,如植物多酚、维生素A和维生素E等。但是,这类试验大多思路较窄,着眼点片面,缺乏系统性探讨。本文在详述氧化应激与免疫关系的基础上,对外源抗氧化剂调控机体免疫系统的研究现状进行了分析与总结。     

围产期奶牛氧化应激、抗氧化防御系统及其与机体炎症反应的关系

氧化应激诱导机体自由基的产生是有氧代谢的一个组成部分。活性氧(reactiveoxygenspecies,ROS)是机体正常代谢过程和某些白细胞群体在疾病防御过程中产生的。越来越多的研究表明,机体组织和细胞产生的氧化损伤会直接或间接诱导许多疾病的发生,进而影响动物健康和福利。高产奶牛的生产性能在一定程度上可通过补充抗氧化剂来优化。概述了氧化应激的研究进展,综述了围产期奶牛氧化应激、抗氧化防御系统及其与炎症反应的关系,以期为进一步揭示抗氧化剂预防免疫功能障碍和宿主组织氧化损伤的分子机理,避免围产期奶牛发生由氧化应激诱导的代谢病和临床型疾病提供新思路。     

动物氧化应激及其营养调控措施研究进展

动物机体内存在氧化还原平衡,正常状态下保持相对的稳态,当环境或自身状态发生改变时,这种平衡可能会被打破,进而引发机体氧化应激。研究发现,引起氧化应激的因素有很多：如环境因素、动物自身状态改变和外源致病菌以及病毒等,这些因素造成的氧化应激对动物的健康状况、生产性能和繁殖功能等方面会产生不同程度的影响,严重时甚至引发动物死亡,因此,寻求和添加安全有效的抗氧化制剂以调节动物氧化还原状态具有重要的现实意义。目前,针对动物氧化应激的营养性添加剂主要有益生菌、维生素、微量元素、激素类和植物类活性物质等。本文对引发动物氧化应激的主要原因和其对动物产生的影响进行了总结,并概括了具有缓解动物氧化应激功能的营养性饲料添加剂,以期为动物氧化应激和其缓解策略的进一步研究提供参考。     

动物肠道氧化应激及抗氧化剂干预作用研究进展

氧化应激是机体内一种有害的氧化还原失衡状态,氧化应激是导致疾病的重要因素之一。肠道作为最易受氧自由基攻击的器官,研究肠道氧化应激机理与寻找预防和修复肠道氧化损伤的方法对发挥肠道机能有重要意义。实验证明抗氧化剂可以显着降低肠道氧化应激水平,目前许多抗氧化剂已经用于肠道氧化损伤的干预研究,本文将对动物肠道氧化损伤的机制及抗氧化剂的干预作用做一综述。     

Antiarrhythmic and Electrophysiologic Effects of Flecainide on Acutely Induced Atrial Fibrillation in Healthy Horses

Background

Only few pharmacologic compounds have been validated for treatment of atrial fibrillation (AF) in horses. Studies investigating the utility and safety of flecainide to treat AF in horses have produced conflicting results, and the antiarrhythmic mechanisms of flecainide are not fully understood.

Objectives

To study the potential of flecainide to terminate acutely induced AF of short duration (≥15 minutes), to examine flecainide‐induced changes in AF duration and AF vulnerability, and to investigate the in vivo effects of flecainide on right atrial effective refractory period, AF cycle length, and ventricular depolarization and repolarization.

Animals

Nine Standardbred horses. Eight received flecainide, 3 were used as time‐matched controls, 2 of which also received flecainide.

Methods

Prospective study. The antiarrhythmic and electrophysiologic effects of flecainide were based on 5 parameters: ability to terminate acute pacing‐induced AF (≥15 minutes), and drug‐induced changes in atrial effective refractory period, AF duration, AF vulnerability, and ventricular depolarization and repolarization times. Parameters were assessed at baseline and after flecainide by programmed electrical stimulation methods.

Results

Flecainide terminated all acutely induced AF episodes (n = 7); (AF duration, 21 ± 5 minutes) and significantly decreased the AF duration, but neither altered atrial effective refractory period nor AF vulnerability significantly. Ventricular repolarization time was prolonged between 8 and 20 minutes after initiation of flecainide infusion, but no ventricular arrhythmias were detected.

Conclusions and Clinical Importance

Flecainide had clear antiarrhythmic properties in terminating acute pacing‐induced AF, but showed no protective properties against immediate reinduction of AF. Flecainide caused temporary prolongation in the ventricular repolarization, which may be a proarrhythmic effect.     

氧化应激对断奶仔猪的影响及营养的调控作用

氧化应激与仔猪健康关系密切,营养物质影响仔猪机体的氧化还原水平和健康。仔猪出生后遭遇断奶、疾病、免疫等应激,损伤机体健康,其在一定程度上体现机体抗氧化能力的改变。本文从断奶对仔猪氧化还原系统的影响、氧化应激对断奶仔猪的影响以及营养缓解氧化应激的作用进行综述,初步探讨氧化应激作为判断仔猪健康的生物标识的可行性。     

植物多酚对氧化应激与炎症信号通路的调控机制

炎症及氧化应激是造成动物机体组织和器官损伤的主要原因之一,肠道炎症可造成肠黏膜损伤,进而影响其屏障功能,减弱动物对外界刺激的防御能力。植物多酚具有抗氧化、抗炎、调节肠道菌群等多种潜在功效,且具有低毒、无耐药性等特点,因此,在新型饲料添加剂的开发中具有广阔的应用前景。但目前大部分植物多酚在动物体内的代谢及调控机制尚不明确,这极大阻碍了其合理有效利用。本文基于近期研究就植物多酚对氧化应激与炎症信号通路的调控机制进行综述,为其在新型饲料添加剂中的应用提供理论依据。     

Relationship of Some Oxidative Stress Biomarkers in Jumper Horses After Regular Training Program

In the present study, the redox status of blood samples, by assessing the total oxidant status (TOS), the total antioxidant capacity (TAC), and the oxidative stress index (OSI), together with the nitric oxide radical (NO^•) metabolite (NOx) content, was evaluated in trained horses. Moreover, the oxidative damage to lipids and proteins, analyzed as thiobarbituric acid reactive substances (TBARS) and advanced oxidation protein products (AOPP), was also assessed. Twenty-five regularly trained Italian Saddle horses (7–10 year old, 12 geldings and 13 females, mean body weight 480 ± 30 kg) were enrolled in this study. Animals were carried on with their specific training programs for jumpers for 6 days per week with a day of rest, during which blood sampling was performed. On obtained serum samples, TOS, TAC, NOx, TBARS, and AOPP were measured. Our results showed significant linear correlations among markers of redox potential (TAC, TOS, and OSI) and among TOS and NOx with serum markers of lipid and protein oxidative injury (TBARS and AOPP). Furthermore, multiple linear regression analysis has shown that lipid peroxidation and protein oxidation levels are related to the content of oxidant substances (TOS and NOx). The obtained data can be useful to assess the status of an athletic horse and its adaptability to physical effort, providing an opportunity to modify the training schedule to achieve the desired performance.