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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A comparison of the effects of packed red blood cell transfusion and Oxyglobin® in canine babesiosis

Zambelli, A.B. (Anthony Brett) 28 July 2008 (has links)
Blood transfusion forms a mainstay of the treatment of a variety of illnesses, and is lifesaving. Nonetheless, it is not without its risks and drawbacks. Blood transfusion is a cornerstone in the treatment of canine babesiosis. The development of blood alternatives has received attention in recent times. Blood alternatives offer much of what natural blood does but without many of the associated drawbacks. These include disease transmission, transfusion reactions, poor in vitro and in vivo shelf-life and special storage and administration requirements. One product, Oxyglobin®, is the first commercially available, veterinary-licensed, haemoglobin-based oxygen carrying solution (HBOCS). Although licenced for use in canine babesiosis, this colloidal “Oxygen Bridge” has never been evaluated against the gold standard of therapy, isovolumic packed red blood cell transfusion (pRBCT). This investigation was conducted to evaluate important aspects the equivalence of these two treatments in a field situation of naturally-infected dogs. Given the cost of HBOCS, they are unlikely to be commonly used by the practicing veterinarian in the treatment of canine babesiosis. Nonetheless, similarities in efficacy would bolster the case for and further research into blood substitutes of this and other classes, and may open the way to evaluation of HBOCS for falciparum malarial anaemia, a disease similar in many respects to canine babesiosis. / Dissertation (MMedVet)--University of Pretoria, 2007. / Companion Animal Clinical Studies / unrestricted
2

Modelling lung and tissue gas transfer using a membrane oxygenator circuit : determining the effects of a volatile anaesthetic agent and a haemoglobin substitute on oxygen, carbon dioxide and nitric oxide diffusion

Dunningham, Helen January 2011 (has links)
A novel in vitro membrane oxygenator circuit was developed to test gas exchange where particular elements could be examined whilst keeping other variables constant. The circuit comprises two membrane oxygenators connected to form a continuous blood circuit resembling venous and arterial blood conditions. The effects of Isoflurane, a volatile anaesthetic, on oxygen transfer were investigated. RBC resistance to nitric oxide diffusion (DNO) was tested in this circuit by haemolysis and addition of the haemoglobin-based-oxygen-carrier (HBOC) Oxyglobin. The circuit was primed with equine blood flowing at 2.5 l/min. The oxygenator was ventilated with 5 l/min air/oxygen/N2 mix providing a range of FiO2. The deoxygenator received 5 l/min 5% CO2 in N2 with 0.2-0.3 l/min CO2. Isoflurane 1%, NO 4000-16000 ppb and CO 0.03% were added to the oxygenator gas. Uptake of O2, CO2, CO and NO were calculated by gas inlet and outlet concentrations and flow rates. Arterial and venous oxygen dissociation curve (aODC and vODC) comparisons were made. Isoflurane uptake by the circuit blood was evident and 1% Isoflurane did not affect oxygen uptake (p=0.981), aODC or vODC (p=0.311 and p=0.751). Haemolysis did not affect O2 or CO2 transfer but increased DNO (p<0.001). 250ml free Hb solution addition to the circuit increased DNO by 91% (p<0.0001). Addition of 250ml Oxyglobin increased DNO by 143% from 7.41±2.77 to 17.97±1.83 ml/min/mmHg. Oxyglobin caused a right shift of aODC and vODC (p<0.0001) but NO-bound Oxyglobin caused a left vODC shift (p<0.0001). Conclusion: Isoflurane administered via a membrane oxygenator does not affect O2 uptake or carriage in the blood. RBC surroundings provide significant resistance to DNO in circuit tests. Significant uptake of NO by Oxyglobin supports the potential of HBOCs to scavenge endothelial NO in vivo, causing vasoconstriction.
3

Erythrocyte-Associated Transients in Capillary PO2 in the Rat Spinotrapezius Muscle During Hemodilution with Hespan and a Hemoglobin-Based Oxygen Carrier

Barker, Matthew 01 January 2005 (has links)
Hemoglobin-based oxygen carriers for use as transfusion fluids have emerged as a leading technology directed at stemming shortages of a safe blood supply and providing a readily available resuscitation fluid in various trauma situations. The purpose of this investigation was to determine the effects of isovolemic hemodilution with Hespan and a hemoglobin-based oxygen carrier (HBOC) on erythrocyte-associated transients (EATs) in capillary PO2. The particulate nature of blood flow in capillaries, when observed from a stationary observation point, results in fluctuations of PO2 as alternating red blood cells and plasma gaps move through the detection region. Therefore, through experimental methods which provided the necessary temporal and spatial resolution required to make such measurements, EATs can be observed and corresponding PO2 fluctuations can be determined. The spinotrapezius muscle in sixteen Sprague-Dawley rats was exteriorized for intravital microscopy measurements in capillaries. Capillary PO2 was measured using Pd-porphyrin phosphorescence quenching microcopy. The hemodiluents used in isovolemic hemodilution included Hespan, a non-oxygen carrying plasma expander, and Oxyglobin®, a HBOC. Two isovolemic hemodilution steps were performed, reducing the systemic hematocrit to an average of 27.5% after the first step and 13.5% after the second step. Results showed that erythrocyte-associated transients in PO2 can be observed in the rat spinotrapezius with significant differences occurring between red blood cell and plasma gap PO2 under control conditions, isovolemic hemodilution with Oxyglobin after step one, and isovolemic hemodilution with Hespan after step two. This study concludes that EATs are observable and PO2 transients relating to EATs can be measured in the rat spinotrapezius muscle. Furthermore, it can be concluded that the HBOC Oxyglobin caused a decrease in erythrocyte-associated capillary PO2 transients, as well as a general decrease in capillary PO2. In addition, this study concludes that erythrocyte-associated capillary PO2 transients can best be observed under control conditions and after step two of isovolemic hemodilution with Hespan.
4

Efficacité d'un substitut sanguin (Oxyglobin) chez le chien anémique

Kelly, Nancy 07 1900 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal. / L'Oxyglobin (Biopure Corporation) est une solution d'hémoglobine bovine ultrapurifiée commercialisée aux États-Unis depuis janvier 1998 pour le traitement des anémies chez le chien. La posologie recommandée par la compagnie Biopure est de 30 ml/kg quel que soit le seuil d'hémoglobine utilisé pour débuter une transfusion. Cette posologie a été déterminée en laboratoire chez des chiens sévèrement anémiques (seuil de transfusion en hémoglobine de 30 g/L). Le premier objectif de notre étude était d'évaluer, chez le chien modérément anémique (seuil de transfusion en hémoglobine de 50 g/L), la posologie nécessaire pour atteindre la limite inférieure de la tolérance à l'anémie, soit de 70 g/L. Le deuxième objectif consistait à étudier la réponse érythropoïétique après administration de la solution Oxyglobin. Le but ultime de ce travail était de déterminer l'immunotolérance du produit après son administration répétitive sur une période de 50 semaines. Un nombre total de 26 chiens mâles de race Beagle ont été utilisés. Les chiens étaient splénectomisés au moins une semaine avant le début de l'étude. Dans tous les groupes expérimentaux, l'anémie était induite par hémodilution jusqu'à ce que la concentration de l'hémoglobine atteigne un seuil de 50 g/L. Après l'induction de l'anémie, 18 chiens, répartis en 3 groupes de 6 chiens, ont reçu la solution Oxyglobin à des volumes de 7, 1 O ou 15 ml/kg. Quatre (4) chiens ont reçu du sang entier à un volume de 10 ml/kg et un dernier groupe de 4 chiens n'a reçu aucun traitement. En ce qui concerne la posologie minimale efficace, le volume de 15 ml/kg d'Oxyglobin a été le seul volume administré pouvant entraîner une augmentation de la concentration en hémoglobine à des valeurs supérieures à 70 g/L, jusqu'à 12 heures après le traitement. Il faut noter qu'à cette posologie, les valeurs du contenu artériel en oxygène étaient comparables ou même plus élevées que celles du sang entier, et ce, jusqu'à 24 heures après le traitement. L'administration de l'Oxyglobin ne compromet pas la libération de l'érythropoïétine, ni la production de réticulocytes suite à l'induction de l'anémie. L'administration répétitive de la solution Oxyglobin engendre une production cumulative d'lgG anti-hémoglobine bovine reliée au nombre d'administration chez la plupart des chiens traités. Aucun effet pathogène rénal ou hépatique n'a été observé. De plus, aucun dépôt d'lgM, lgA, lgM ou de C3 n'a été identifié lors de l'évaluation histochimique du foie ou des reins. Finalement, la présence d'lgG anti-hémoglobine bovine dans le sérum n'interfère pas avec la capacité de liaison de l'hémoglobine bovine même en présence des concentrations· d'lgG très élevées. En outre, l'absence de réaction systémique attribuable à des administrations répétitives de la solution Oxyglobin fut une observation importante. Il a été conclu que la posologie de 15 ml/kg de la solution Oxyglobin est adéquate pour le traitement de l'anémie modérée. De plus, l'administration répétitive de la solution Oxyglobin peut être préconisée puisqu'elle ne produit pas de changement physiologique ou de réaction systémique reliée à la production d'anticorps anti-hémoglobine bovine.

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