Evaluation of fluorescein dye as an indicator of small intestinal viability in the horse

In 6 horses, 2 types of ischemic lesions were created in small intestinal segments by selective ligation of vessels and intestinal wall for 1, 2, or 3 hours. After confirming the ischemia by IV injection of sodium fluorescein, the ligatures were released. Five minutes later, the fluorescent patterns were documented photographically. Observed patterns ranged from normal (identical to that observed in unaffected bowel) to a patchy distribution of non-fluorescence (indicating incomplete perfusion). None of the experimental segments was normal when reevaluated 1 month later. The typical appearance included fibrosis, adhesions, and thickening of the bowel wall. It was concluded that IV injection of fluorescein can be used to indicate perfusion of the intestine, but that this is not the only criterion for determining clinical outcome in cases of intestinal ischemia in horses.     

The pathophysiology of intestinal damage: effects of luminal distention and ischemia

Intestinal edema, luminal distention, and ischemia are common pathologic processes involved in producing the intestinal damage found during surgical exploration for acute abdominal disorders in the horse. The severity of intestinal edema depends on the degree of altered intravascular forces and changes in capillary permeability. Capillary hydrostatic pressure rises as the less pliable venules and veins become occluded during intestinal obstruction. Concurrently, the production of various endogenous products that damage the vascular wall leads to increases in capillary permeability and protein exudation, causing fluid movement into the interstitium and consequent tissue edema. The information presently available indicates that luminal distention does not produce the morphologic damage observed during natural conditions. However, slight intestinal edema was observed with experimental distention of the equine small intestine. Although the effects of increased luminal pressure appear minor, in the overall scheme of intestine damage, many processes are occurring together, and the luminal distention may be additive in the production of intestinal damage. The intestinal damage occurring during natural obstructions is most likely related to both the severity of the ischemia and the subsequent reperfusion injury. Experimentally, an ischemic insult produces a consistent sequence of mucosal alterations to both the equine small and large intestine. Severity of ischemia may be the limiting factor in determining the clinical outcome in cases in which the ischemic insult is irreversible; however, if the intestinal tissue survives the ischemia, the reperfusion injury may substantially increase the damage, producing an irreversible injury. The proposed mechanisms responsible for the reperfusion injury include the presence of highly reactive cytotoxic oxygen radicals. The intestinal epithelium and vascular endothelium are both capable of producing these unstable compounds. Secondly, the influx and activation of neutrophils may also release oxygen radicals. During experimental ischemia, neutrophils gradually move to the affected area; however, during reperfusion their numbers dramatically increase and may play a significant role in producing intestinal damage. Therapy for intestinal damage involves first determining the viability of the affected intestine. All nonviable bowel should be resected and viable intestine anastomosed. The care and maintenance of intestine of questionable viability are presently based on therapy in humans and experimental information concerning the pathophysiologic mechanisms of intestinal ischemia.(ABSTRACT TRUNCATED AT 400 WORDS)     

Resection and anastomosis of small intestine: current methods applicable to the horse

Intraoperative techniques for assessing the viability of ischaemic bowel are discussed. Intravenous administration of sodium fluorescein appears useful but further investigation of the method is required. Methods of resection and anastomosis of small intestine are described and illustrated, including the use of automatic stapling instruments.     

Intestinal healing and methods of anastomosis

Optimal intestinal healing occurs when like layers of the intestinal wall are aligned. Hand-sewn, double-layer, end-to-end anastomosis that apposes the mucosa and produces slight inversion of the seromuscular layer is recommended to minimize adhesion formation and provide reasonable alignment of the intestinal layers. Stapled, everted, triangulated, end-to-end anastomosis is not recommended because of extensive adhesion formation and poor healing of the intestinal layers. The preferred stapled techniques create an inverting, side-to-side stoma between the bowel segments.     

Prevention of Intraabdominal Adhesions in Ponies by Low-dose Heparin Therapy

An ischemic bowel model was used to stimulate adhesion formation in eight ponies. Heparin (40 USP u/kg) or saline was administered intravenously at surgery and was continued subcutaneously every 12 hours for 48 hours to evaluate the efficacy of heparin in preventing intraabdominal adhesions. Ponies were euthanatized after 6 weeks, and postmortem examinations were performed. A statistically significant difference was found between the heparin-treated and the control groups. Adhesions developed in three of four control ponies, and adhesions did not develop in three of four heparin-treated ponies. None of the adhesions resulted in clinical disease. In this study, heparin decreased the formation of adhesions in ponies after experimentally induced intestinal ischemia.     

Effects of intestinal ischemia on in vitro activity of adjacent jejunum in samples obtained from ponies.

OBJECTIVE: To determine whether intestinal ischemia would alter activity of the jejunum in vitro or alter staining characteristics for certain types of enteric neurotransmitters. SAMPLE POPULATION: Jejunal samples obtained from 10 ponies. PROCEDURE: Jejunal samples were obtained from locations proximal and distal to an area of small intestine made ischemic for 60 minutes. A portion of each sample was stained to detect substance P-like immunoreactivity, cholinergic and adrenergic neurons, and nitric oxide synthase. Portions of the remaining samples were suspended in muscle baths. General activity patterns (frequency and amplitude of contraction), responses to neuronal depolarization induced by electrical field stimulation (EFS), and responses to 1 microM norepinephrine (NE) were compared with responses of a normal section of small intestine obtained prior to ischemic insult. RESULTS: Staining patterns were not altered. Proximal and distal sections had evidence of decreased contractility, compared with the normal section. Contraction frequency also was decreased, and distal sections had lower contraction frequency than proximal sections. Relaxation responses were decreased in distal sections. Responses to NE differed significantly for distal and proximal sections, compared with normal sections. CONCLUSIONS AND CLINICAL RELEVANCE: Short-term ischemia can significantly affect adjacent bowel. Contractile and relaxation responses are impaired. Discrepancies in intestinal motility patterns and alterations in response to NE for sections proximal and distal to ischemic intestine could lead to clinical ileus or slowed transit of ingesta.     

黄土高原森林边缘区退耕地植被自然恢复及其对土壤养分变化的影响

对黄土高原森林边缘区退耕地植被自然恢复及其对土壤养分变化影响的研究结果表明,该区植被演替虽然总体上具有典型森林区植被演替的特征,但多年生禾草阶段与多年生蒿类演替并没有表现出严格的先后顺序;群落物种多样性、丰富度、均匀度及物种替代率随植被恢复表现出由低而高,而后又降低的变化趋势。其变化的峰值阶段与多年生禾草阶段和多年生蒿类交错出现的阶段相吻合。土壤养分变化表明,该阶段也是退耕地养分消耗与累积处于平衡的阶段,具有明显的过渡性。不同养分对植被恢复的响应程度从高到低表现为:有效氮>有机质>全氮>速效钾>速效磷>全磷,而且在植被恢复过程中土壤养分累积具有明显的表聚性,尤以有机质、全氮、有效氮和速效钾表现明显。各养分的相关性分析表明,土壤有机质、全氮、有效氮与速效钾相互间显著相关,而全磷和速效磷与其余各养分间的相关性较小,而且磷素养分在植被恢复过程中的变化较小。对植被演替进行人工调控,应充分认识养分变化的这种差异。     

Probiotics in veterinary medicine: a review

The mammalian gastrointestinal tract is a complex consisting of the intestinal epithelial cells, the mucosal immune cells and the endogenous microflora. Since a couple of years, probiotics are used in animal production to improve performance. But there are only few results available on the immune modulating effects of pro- and prebiotics in human and veterinary medicine. Recent studies are promising that pro- and prebiotics can be used as an alternative to conventional therapy with immune suppressive drugs in patients with inflammatory bowel disease or dietary hypersensitivity. Yet further randomized and placebo-controlled studies are needed to clarify these mechanisms in vivo.     

Xanthine oxidase formation during experimental ischemia of the equine small intestine.

We hypothesized that xanthine oxidase plays a role in the postischemic reperfusion injury in the equine small intestine. Under anesthesia, four horses and two ponies underwent ischemic strangulating obstructions of segments of the proximal jejunum, mid-jejunum and ileum. Prior to vascular occlusion, and at 1 h and 2 h of ischemia, full-thickness intestinal biopsies were collected for histopathological evaluation and for determination of combined xanthine dehydrogenase (XDH) plus xanthine oxidase (XO) activity, and XO activity alone. The level of XO activity was expressed in percentage according to the ratio of XO/(XDH + XO). We found a nearly threefold increase in the combined level of XDH plus XO activity from ileum to duodenum (p less than 0.04). However, the preischemic level of % XO activity did not vary significantly (p = 0.61) between segments of jejuno-ileum. Likewise, no significant difference was noted between intestinal segments after ischemia. Therefore, the data from all intestinal segments were pooled for each time and analyzed using Wilcoxon's signed rank test (one-tailed). Compared to the pre-ischemic level of % XO activity (median 27%), the % XO activity increased after 1 h of ischemia (median 37.0%), reaching statistical significance (p = 0.016). There were no statistical differences between the preischemic % XO activity and the % XO activity in non-ischemic bowel at the end of the anesthetic period. During ischemia, % XO activity increased, which lends credence to the importance of xanthine oxidase in previously-documented reperfusion injury in the equine small intestine.     

Induction of peritoneal adhesions with small intestinal ischaemia and distention in the foal

Twenty-two foals were divided into groups of intestinal distension and intestinal ischaemia as methods to induce peritoneal adhesions. In the first group, the lumen of a segment of distal small intestine was occluded without extramural vascular compromise and distended with lactated Ringer's solution to a constant pressure of 25 cm H2O for 2 h within the abdomen. The ischaemic group underwent 70 mins total vascular occlusion of identical segments of bowel. Serosal biopsies were obtained before and after each experimental procedure and following 60 mins of reperfusion. Similar biopsies were harvested from a control group of foals with no bowel occlusions. The foals were destroyed 10 days after surgery and tissues collected for histological and ultrastructural evaluation. Experimental and control mesothelial surfaces were denuded histologically immediately after experimental occlusions. Serosal oedema and cellular infiltration were observed following reperfusion of the ischaemic segments but were present immediately after 2 h of distension. All foals had developed bowel-to-bowel and bowel-to-mesentery adhesions of the experimental segments. Control foals under 30 days old exhibited mesenteric contraction and thickening of the isolated segment whereas those older than 30 days had little or no mesenteric thickening or contraction. Histologically, in the experimental segments, fibrous tissue had formed on the outer boundary of the original serosa, and new mesothelial-like cells were present on the surface of fibrous tissue in some areas. Some serosal fibrosis was also seen in most of the control segments.     

Mechanisms of Gastrointestinal Ischemia-Reperfusion Injury and Potential Therapeutic Interventions: A Review and Its Implications in the Horse

Restoration of blood flow after a period of intestinal ischemia is necessary to maintain cell function and viability; however, the reintroduction of oxygen can initiate a cascade of events that exacerbates tissue injury. Intestinal I-R injury is manifested as increased microvascular and mucosal permeability, and mucosal necrosis. Reperfusion injury begins with the accumulation of hypoxanthine from ATP metabolism and the conversion of XDH to XO during ischemia. Upon reperfusion, the XO catalyzes the conversion of hypoxanthine to superoxide radicals in the presence of oxygen. Superoxide radicals are further reduced to highly reactive hydroxyl radicals, which initiate lipid peroxidation. Lipoperoxidation causes functional and structural alterations in cell membrane lipids and can release numerous inflammatory mediators, which exacerbate tissue damage. Neutrophils are recruited into tissues during ischemia and on reperfusion; then they undergo degranulation and release destructive products (proteases and OFRs), which mediate further tissue injury. A limited number of experimental studies in the gastrointestinal tract of horses have shown I-R injury. Additional studies are necessary to further elucidate and sequence the precise pathophysiologic mechanisms occuring in the equine intestine during I-R. Therapy should be focused on prevention of I-R injury by pharmacologic or chemical inhibition or modification of these pathophysiologic pathways. Selected pharmacologic agents or drug combinations may offer novel, scientifically relevant and yet practical approaches to alleviating intestinal I-R injury in horses. This may improve survival of horses with naturally acquired intestinal strangulation obstruction.     

Chronic intestinal diseases in the dog: a review

The most commonly encountered chronic enteropathies in dogs are inflammatory bowel disease (IBD), food allergies, and small intestinal bacterial overgrowth. Recent research in the field of immunopathogenesis of IBD and food allergy in human beings have made available new therapeutic options with immunomodulatory drugs. However, the mechanisms involved in the pathogenesis of canine IBD and food allergy have not been elucidated so far. Further studies focusing on the immunological dysregulation in the mucosa as well as clinical trials with new therapeutic modalities are needed to improve our knowledge and approach to these chronic diseases in dogs.     

乙酰荧光素(FDA)在小鼠和猪卵母细胞活力评价上作用

以小鼠卵母细胞和猪卵母细胞为材料研究了FDA活力检测上的应用。结果表明：1)受精卵和卵母细胞均有积聚FDA(乙酰荧光素)的能力；2)猪卵巢在不同温度保存之后，其卵母细胞的积聚FDA(乙酰荧光素)的能力有明显改变。这些结果表明，可以用积聚FDA(乙酰荧光素)的能力检测卵母细胞的活力。     

Plasma intestinal fatty acid binding protein (I-FABP) concentrations increase following intestinal ischemia in pigs

Intestinal fatty acid binding protein (I-FABP) is an intracellular epithelial protein in the intestinal mucosa of many animals. I-FABP appears in the circulation following epithelial damage, and in humans, is proven to be a parameter for damage to the mucosa. In this paper, an ELISA test designed for human I-FABP analysis was used to assay pig blood samples. The test recognized I-FABP cloned from pig small intestine and expressed in Escherichia coli. Furthermore, in our experimental model of (low flow) intestinal ischemia and reperfusion a significant rise in plasma I-FABP concentrations 15-30 min after clamping of the mesenteric artery was demonstrated. This is the first report that in pigs circulating I-FABP is a useful marker for (mild) intestinal injury, and could possibly be used to monitor (intestinal) health in clinical practice.     

高速公路岩质边坡植被恢复初期喷播基材养分动态

以京承三期高速公路岩质边坡植被恢复工程为依托，研究了2种厚层基材在喷播第1年的养分动态变化，其中基材A泥炭∶种植土为9∶1，基材B种植土∶植生基质为6∶4。研究结果表明，2种基材的pH值变化很小，表明酸碱性在植被恢复第1年变化较小；基材A有机质、全氮、有效磷、速效钾的含量变化趋势大体一致，均表现为先下降后上升，各值在7月份达到最低，养分先降后升的变化趋势可能与基材A坡面以草本植物为主有关，前期草本植物生长迅速，养分需求大，而夏季草本植物生长停滞甚至退化，枯草层分解贡献一部分养分；基材B养分变化趋势不同，除有效磷在7月份有增加外，其他养分表现为随生长时间持续下降。方差分析表明，2种基材养分变化差异显著（P＜0.05）；不同时间同一基材养分差异不显著。2种基材不同的变化趋势，认为除了与基材组成中泥炭和有机质分解有关外，与坡面的草本植物与灌木植物也有关。研究基材养分动态的变化，对改进基材的配置具有重要的意义。     

ULTRASONOGRAPHIC APPEARANCE AND ETIOLOGY OF CORRUGATED SMALL INTESTINE

An ultrasound pattern of corrugated, and sometimes thickened, bowel wall has been associated with pancreatitis and small intestinal lymphangiectasia. In a retrospective study, records of dogs and cats with an ultrasound diagnosis of corrugated bowel were examined for age, breed, gender, presenting complaint, abdominal radiographic results, and final diagnosis. Eighteen dogs and six cats had an ultrasound diagnosis of corrugated bowel. The final diagnosis was pancreatitis (12 of 24), peritonitis (4 of 24), enteritis (2 of 24), pancreatic neoplasia (2 of 24), diffuse abdominal neoplasia (1 of 24), lymphocytic-plasmacytic enteritis (1 of 24), thrombosis/infarction (1 of 24), and protein-losing enteropathy and acute renal failure (1 of 24). The presence of bowel wall corrugation, although a nonspecific finding, should alert one-to the possibility of pancreatitis, enteritis, peritonitis, neoplasia, or bowel wall ischemia.     

The biological stress of early weaned piglets

Pigs experience biological stress such as physiological, environmental, and social challenges when weaned from the sow. The process of weaning is one of the most stressful events in the pig’s life that can contribute to intestinal and immune system dysfunctions that result in reduced pig health, growth, and feed intake, particularly during the first week after weaning. Technological improvements in housing, nutrition, health, and management have been used to minimize some of the adverse effects of weaning stress, but a greater understanding of the biological impact of stress is needed to improve strategies to overcome weaning stress. The focus of this review paper is to briefly describe how the biological stress associated with weaning impacts intestinal morphology, structure, physiology, and intestinal immune responses that can impact subsequent production efficiencies such as growth, intake, morbidity, and mortality.     

The equine teniae coli: An electrophysiological study

Previous morphological studies of the equine teniae coli (intestinal bands) have shown them to be highly innervated. In this study, EMG electrodes were placed in the wall of the left ventral colon in order to determine whether intestinal bands serve as major conduits of myo-electrical activity. Specifically, electrodes were implanted in the lateral mesocolic band and the adjacent tenia-free bowel of 6 horses. In 3 of these horses, a 1 cm length of the intestinal band was excised to determine if a lesion of this size would ablate local waves of depolarization. Our results indicate that sequential EMG activity persisted despite this small, focal excision. The persistence of sequential EMG activity might reflect the importance of constantly regenerating stimuli to the intestinal motility of the horse. Whether making similar or somewhat larger lesions in all four teniae of the left ventral, colon would more definitively disrupt normal pelvic flexure peristalsis will require further research.     

COLOR DOPPLER ULTRASONOGRAPHY IN PREDICTION OF THE REDUCIBILITY OF INTUSSUSCEPTED BOWEL IN 15 YOUNG DOGS

Color Doppler ultrasonography was performed in 15 young dogs with intestinal intussusception to test the hypothesis that color Doppler findings can be used as a predictor of the manual reducibility of the intussusception at celiotomy. Color flow Doppler ultrasonography indicated blood flow within mesentery of the intussuscepted bowel in 12 of 15 dogs and reduction was achieved in nine of these 12 dogs (75%). In the remaining three dogs and in three dogs where no color Doppler signal were observed, an irreducible intussusception was confirmed at celiotomy. Color Doppler ultrasonography is a useful method for predicting the reducibility of intussusception in dogs.