Heparin: A Review of its Pharmacology and Therapeutic Use in Horses

Heparin is used clinically in horses to treat hemostatic abnormalities associated with severe gastrointestinal disease, septicemia, and endotoxemia. The primary anticoagulant effect of heparin is through the suppression of thrombin-dependent amplification of the coagulation cascade, and inhibition of thrombin-mediated conversion of fibrinogen to fibrin. Heparin may be of benefit in preventing the complications associated with hypercoagulable states such as jugular vein thrombosis, laminitis, and organ failure. Heparin may also be beneficial in the prevention of intraabdominal adhesions after gastrointestinal surgery, and in amelioration of hemodynamic abnormalities associated with endotoxic shock. Because a sequential rise in serumheparin concentration occurs during a uniform dosage regimen, a decreasing dosage regimen is recommended. The initial dose recommended is 150 U heparin/kg body weight subcutaneously, followed by 125 U heparin/kg body weight subcutaneously, every 12 hours for six doses. The dose should be decreased to 100 U heparin/kg body weight subcutaneously, every 12 hours, after the seventh dose. Anemia, hemorrhage, thrombocytopenia, and painful swelling at injection sites are complications of heparin administration in horses.     

秋水仙素诱导鲁梅克斯四倍体的研究

利用秋水仙素对鲁梅克斯进行多倍体诱导,获得鲁梅克斯四倍体植株。利用形态学与细胞学的方法对鲁梅克斯四倍体植株与二倍体植株进行了观察研究。结果表明,鲁梅克斯四倍体表现为生长减慢、叶形指数变小、叶片增厚、种子千粒重增加、气孔变大、气孔频度降低、气孔内叶绿体含量增加和SPAD值变大。     

Colchicine treatment in a dog with hepatoportal fibrosis

A two-year-old female spayed English setter with hepatic encephalopathy was found to have hepatoportal fibrosis and acquired portosystemic shunts on laparotomy and liver biopsy. The dog was treated symptomatically with a low-protein diet, lactulose and metronidazole, while colchicine was given as antifibrotic therapy. There was a gradual improvement in clinical signs and liver function until 30 months after first presentation, when the dog developed severe haematuria caused by renal infarction of unknown aetiology. Post mortem examination revealed hepatic fibrosis to be unchanged. This case illustrates that long term survival may be possible in canine hepatoportal fibrosis and suggests that colchicine may be effective in improving liver function and slowing progression of hepatic fibrosis.     

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.     

Interleukins: Biological Properties and Therapeutic Potential

Interleukins are biologically active glycoproteins derived primarily from activated lymphocytes and macrophages. Tremendous insight into the biochemical and biological properties of interleukins has been gained with advances in recombinant DNA technology, protein purification, and cell-culture techniques. The biological properties of interleukins include induction of T-lymphocyte activation and proliferation, augmentation of neutrophil, macrophage, and T-lymphocyte cytotoxicity, and promotion of B lymphocyte and multilineage bone marrow stem-cell precursor growth and differentiation. Interleukins may play a role in the pathogenesis of several important diseases. Interleukin therapy is likely to play an important role in the treatment of cancer, infectious diseases, and immunodeficiency syndromes.