Browsing by Subject "Heparin"
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Item Alkylmaltoside mediated nasal delivery of low molecular weight Heparin: In vitro and in vivo evaluations(Texas Tech University, 2004-05) Mustafa, FatimaThis study is designed to test the hypothesis that alkylmaltosides could be used as efficacious absorption enhancers for nasal delivery of enoxaparin, a low molecular weight heparin. The efficacy of the absorption enhancers was studied by monitoring the changes in plasma anti-factor Xa level after nasal administration of enoxaparin into anesthetized rats. In vivo reversibility study was performed to determine if the effect of the absorption enhancers on nasal membrane is reversible after acute administration of the formulations. Enoxaparin was formulated with alkylmaltosides containing varying alkyl chain lengths (octyl-, decyl-, dodecyl,- and tetradecyl-maltoside) in order to assess the role of hydrophobic chain length on the potency of the absorption enhancers. The mechanisms by which alkylmaltosides enhance permeation of enoxaparin across epithelial cells were investigated by studying the transport of radiolabelled enoxaparin and mannitol across human bronchial epithelial cells. In vitro cytotoxicity and transepithelial electric resistance recovery studies were performed to further assess the toxicity of the agents on epithelial cells. The results demonstrate that alkylmaltosides enhance enoxaparin absorption in a chain length and dose dependent manner. Of the alkylmaltosides tested, tetradecylmaltoside was most efficacious in enhancing nasal absorption of enoxaparin. It was found that the effect of octylmaltoside on nasal membrane diminishes with time and nasal mucosa re-establishes normal physiological barrier to drug absorption. Permeabilities of enoxaparin and mannitol increase in the presence of alkylmaltosides, suggesting that alkylmaftosides enhance nasal absorption of LMWH via paracellular route. Cytotoxicity studies revealed that octylmaltoside is the least toxic to the bronchial epithelial cells. Overall, the results suggest that nasal enoxaparin formulated v/ith alkylmaltosides could be a feasible alternative to subcutaneous enoxaparin.Item Modeling and optimization of heparinized collagenous surfaces(Texas Tech University, 1987-08) Chen, Jyh-herngThe primary objective of this research is to determine the optimal conditions of heparin immobilization on collagen powder by varying pretreatment methods, pH of reaction environment and l-ethyl-3(3-dimethylaminopropyl) carbodiimide (i.e., EDC) to heparin weight ratio. This research is part of a series of investigations, of which the ultimate purpose is to develop an implantable small diameter (less than 6 mm diameter) (Parsonnet, 1976) vascular prosthesis which will remain functional while serving as a suitable interposition in the circulatory system.Item Optimization of a dual enzyme system and its effect on collagenous surfaces(Texas Tech University, 1985-12) Lokapur, A. KThe main purpose of this thesis is to co-immobilize heparin and plasmin onto collagenous substrates in an effort to produce a biomaterial possessing both fibrinolytic and thromboresistant properties. The path followed in this research has been to immobilize heparin onto collagenous substrates such as collagen powder, human umbilical vein grafts (HUVG) and chymotrypsin treated goat carotid arteries (GCA), and optimize its activity and stability over a period of time. Several pretreatment procedures have been studied in the case of heparin, which include fibronectin. Endothelial cell growth factor (ECGF),* methanol and hydrazine, hydrogen peroxide, and ammonium hydroxide. The crosslink agent 1-ethy1-3(3-dimethy1-aminopropy1) carbodiimide (EDO has been used to activate the carboxyl groups of the heparin structure. Heparin and plasmin have been co-immobi1ized on collagen powder and the activity of each has been studied in co-bound state. Experiments have shown that heparin in excess of 0.0 1 mg/sq cm can be immobilized on chymotrypsin treated GCA. that would remain stable for more than 3 weeks. In vivo studies have been performed on goats and dogs, the results of which show a patency rate of 807. after 1 week and 707« after 2 weeks, for the 10 samples that have been tested. Of all the pretreatment procedures, ammonium hydroxide appears to produce the most active and stable heparin complex. Co-immobi1ization of heparin and plasmin has shown that bound plasmin activity is increased if collagen powder is preimmobi1ized with heparin. Heparin, however, loses its activity. On the other hand, heparinization of plasmin bound collagen has not been successful. Furthermore, originally bound plasmin loses part of its activity. Experiments have been performed to determine the constants V^g>^ and K^j^ assuming M i chael i s-Menten kinetics for plasmin. The activation energy Eg has also been estimated for plasmin in soluble as well as immobilized form.Item Optimization of co-immobilization of heparin and plasmin(Texas Tech University, 1987-08) Wu, Dauh-rurngNot availableItem Pubertal changes in the expression of fertility associated antigen in Bos indicus and Bos taurus bulls(Texas A&M University, 2007-04-25) Novosad, Aaron M.Fertility Associated Antigen (FAA) produced by the accessory sex glands and contained within the seminal fluid binds heparin and facilitates capacitation in ejaculated sperm, resulting in improved fertility in bulls capable of producing the protein. In this study, a total of 206 bulls derived from three populations were evaluated for the presence or absence of FAA through utilization of the Repro Test at three semen collections over a 60-d period. Across all collections, the percentage of FAA Negative bulls ranged from 13.64 to 36.11%. Within the three populations, 32, 33, and 67 bulls were observed at three different collections, of which 3.03, 9.09 and 4.48% were FAA Negative at all three collections, respectively. Furthermore, 27.27, 33.33, and 20.90% of bulls were observed to have variations within their FAA status after providing an initial FAA Positive result, respectively. Bull age, sperm concentration, progressive forward motility, percent normal sperm, ejaculate volume, and scrotal circumference were determined to be significantly different between FAA Negative and FAA Positive bulls in at least one collection. However, no consistent trend was observed across populations, or collections within a population, with regard to a relationship between these variables and FAA. Furthermore, of fourteen bulls that produced an ejaculate in which no sperm was detected, 78.57% (n=11) were FAA Positive despite the lack of sperm within the ejaculate. No single variable commonly measured to determine bull fertility was consistent in predicting the FAA status of bulls. The ability to produce FAA precedes puberty and the Repro Test can be used to identify FAA in prepuberal bulls. However, a large percentage of bulls, both prepuberal and peripuberal, are capable of displaying variation in their FAA status (as determined by the Repro Test) over time.