Angiogenesis is a highly regulated process orchestrated by the vascular endothelial growth factor-A (VEGF-A) system of ligands and receptors. Heparin/heparan sulfate (HS) proteoglycans and neuropilin-1 (NRP-1) have been identified as co-receptors for VEGF-A, yet the mechanisms of action have not been fully defined. In the present study, we characterized molecular interactions between receptors and co-receptors and the two major VEGF-A isoforms, using surface plasmon resonance (SPR) and in vitro binding assays. We found that VEGF dissociated 25-times faster from its major signaling receptor, VEGF receptor-2 (VEGFR-2) than from its “decoy” receptor, VEGF receptor-1 (VEGFR-1). We identified a potential mechanism for co-receptors to decrease the dissociation rate and prolong the signaling complex lifetime. Using a systematic approach, we obtained kinetic parameters for each individual interaction in an intercomparable way to measure the effect NRP-1 and HS have on complex stability. Additionally, we demonstrated that these binding events influence VEGF activity within endothelial cells. These parameters can be used in mathematical models to predict therapy outcomes in defined cellular contexts. Furthermore, we optimized a competition-based technique using SPR and structurally defined HS oligosaccharides and demonstrated that it can be used to rapidly measure affinities to HS-binding proteins. We used this method to define interactions and structural and length requirements for heparin/HS interactions with VEGFR-1, NRP-1, and VEGF165, the most relevant VEGF-A isoform, in complex with VEGFR-2 and NRP-1. We show that the structural requirements were distinct for each interaction. We further found that VEGF165, VEGFR-2 and monomeric NRP-1 bound weakly to heparin alone, yet binding to heparin increased synergistically when presented together. This enhanced binding correlated with alterations in VEGF signaling in endothelial cells. We found that soluble NRP-1 increased VEGF binding and activated phosphorylation of VEGFR-2 and Erk1/2 in endothelial cells, and that these effects required sulfated HS. These data suggest that the presence of HS/heparin and NRP-1 may dictate the specific receptor type activated by VEGF and ultimately determine the biological output. The ability of co-receptors to fine-tune VEGF responsiveness suggests the possibility that VEGF-mediated angiogenesis can be selectively stimulated or inhibited by targeting HS/heparin and NRP-1.

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Objective: To determine whether dosage adjustment of enoxaparin during pregnancy, in order to maintain a peak anti-Xa of 1.0-1.2 U/ml, is safe for women with mechanical prosthetic heart valves (MPHV). Methods: This was a prospective observational study performed at Charlotte Maxeke Johannesburg Academic Hospital from 2007 to 2009. 15 women with MPHVs were treated with enoxaparin with dosage adjustment throughout pregnancy to achieve a peak anti-Xa of 1.0-1.2 U/ml. Main outcomes measured were prosthetic valve thrombosis, bleeding and maternal mortality. Results: There was no maternal mortality. None of the women developed valvular thrombosis during pregnancy. Two women developed epistaxis and another developed spotting per vagina. There was no foetal mortality. Conclusion: Our data show that enoxaparin may be administered safely during pregnancy to pregnant women with mechanical prosthetic heart valves when there is dosage adjustment throughout pregnancy in order to maintain an anti-Xa of 1.0-1.2 U/ml.

Respiratory disease represents an important component of small animal emergency medicine. The morbidity and mortality of respiratory disease and inflammation, although poorly defined, is considered to be significant. Much of the therapy used in the stabilization and management of respiratory disease in veterinary patients has been taken from human medicine, including inhalation therapy. Heparin has been shown to have substantial anticoagulant, anti-inflammatory, and antiibrotic effects within the lungs when administered via inhalation in human patients. To date, no studies have evaluated the use of nebulized heparin in dogs. This study is the first to attempt to generate pharmacokinetic data regarding nebulized unfractionated heparin in the dog.

No description available.

Call number: LD2668 .T4 1961 R68

published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

No description available.

uchinok@ccf.org / Background Randomized controlled trials (RCTs) of endovascular therapy for acute ischemic stroke have had inconsistent results. We evaluated the efficacy and safety of endovascular therapy in published RCTs. Methods We performed a systematic review of RCTs of endovascular therapy with thrombolytic or mechanical reperfusion compared with interventions without endovascular therapy. Primary outcome was the frequency of good functional outcome (modified Rankin scale (mRS) of 0-2 at 90 days) and secondary outcomes were mortality at 90 days and symptomatic intracranial hemorrhage (sICH). Random-effects meta-analysis was performed and the Cochrane risk of bias assessment was used to evaluate quality of evidence. Results Ten studies involving 1,612 subjects were included. Endovascular therapy was not significantly associated with good functional outcome (Relative Risk [RR] =1.17; 95% CI, 0.97 to 1.42; p=0.10 and Absolute Risk Difference [ARD] =7%; 95%CI -0.1% to 14%; p=0.05); heterogeneity was moderate among studies (I2=30%). Mortality was unchanged with endovascular therapy (RR=0.92; 95 % CI, 0.75 to 1.13; p=0.45) and there was no difference in sICH (RR=1.20; 95 % CI, 0.79 to 1.82; p=0.39). The quality of evidence was low for all outcomes and the recommendation is weak for the use of endovascular therapy as per GRADE methodology. Conclusions Intra-arterial therapy did not show significant increase in good outcomes and no changes in either mortality or sICH in patients with acute ischemic stroke. We need further RCTs with better design and quality to evaluate the true efficacy of endovascular therapy.