The lymphatic vascular system is necessary for physiological regulation of tissue fluid homeostasis and absorption of dietary fat. Lymphatics also function in the inflammatory response and are involved in pathological conditions such as wound healing and cancer. We show that the Notch signaling pathway is a regulator of both developmental and pathological lymphangiogenesis. Notch1 and Notch4 are expressed by the lymphatic endothelium, and Delta-like ligand 4 (Dll4) is the predominantly expressed Notch ligand in the developing lymphatic vessels of the embryonic dermis and pathological lymphatic vessels of the wounded cornea. Dll4 was able to induce Notch activation in human dermal lymphatic endothelial cells (HDLECs), whereas Jagged1 (Jag1) was not. In HDLECs, Notch signaling is activated in response to Vascular Endothelial Growth Factor (VEGF) or Vascular Endothelial Growth Factor-C (VEGF-C) stimulation. In vitro assays demonstrated that Notch activation inhibits HDLEC proliferation, migration, and capillary network formation; these effects were coincident with increased levels of HEY1 and HEY2, biphasic regulation of VEGFR-3, and decreased levels of VEGFR-2. Using genetic intervention of Notch signaling, we demonstrated that Notch regulates developmental sprouting lymphangiogenesis by restricting growth and sprouting of lymphatics in the murine embryonic dermis. Using pharmacological intervention of Notch signaling, we found that Notch restricted pathological sprouting lymphangiogenesis in the corneal suture assay, which models inflammation-induced lymphangiogenesis. However, pharmacological intervention of Notch signaling did not measurably affect pathological sprouting lymphangiogenesis in an orthotopic tumor model of human breast cancer. Our data from analysis of HDLECs, dermis, and sutured cornea support a role for Dll4-driven Notch signaling in restricting sprouting lymphangiogenesis. Lymphatic specification/separation requires a venous endothelial cell to become a lymphatic endothelial cell, and lymphatic valve formation requires a duct endothelial cell to become a valve endothelial cell. Through analysis of genes regulated by Notch in HDLECs, we demonstrated that Notch determines lymphatic endothelial cell fates. Notch inhibits genes critical for lymphatic specification and separation (PROX1, PDPN), and induces genes important for lymphatic valve formation (FNEIIIA, ITGA9, CX37). We conclude that Notch is a context-dependent regulator of lymphangiogenesis. Notch functions in the tip/stalk, venous to lymphatic, and duct endothelial to valve endothelial cell fate decisions in lymphatic vasculature. Given the critical functions of the lymphatic vasculature in multiple physiological and pathological settings, understanding Notch functions in the lymphatic vasculature is critical to design treatments for conditions caused by lymphatic malfunction.

Many diseases are caused by pathogenic bacteria. A key example of this is sepsis, which is mostly caused by staphylococci and Gram-negative bacteria. In addition, the highly resistant ESKAPE pathogens are responsible for the majority of hospital acquired infections. In order to treat bacterial infections effectively, and to avoid promoting bacterial resistance against antibacterial drugs, the correct agents must be used, for which in turn the detection and identification of pathogenic strains is essential. This research aims to develop selective chromogenic culture media, by introducing new antibacterial agents for the improved selectivity and new chromogenic substrates for selective visualisation of certain bacterial strains. The intention of the major part of this work was to inhibit the growth of commensal bacteria in clinical samples, as they mask the growth of the infection-causing bacteria. New and known compounds were prepared for 3 evaluation as alanine racemase inhibitors. The compounds were tested on a range of clinical pathogenic and non-pathogenic bacterial strains. The molecules developed were based on the amino acid alanine and utilised bioisosteres and other replacements for the carboxylic acid moiety. Key compounds targeted included alanylmethanesulfonamide 27-L, 1-aminoethyl5-oxo-1,2,4-oxadiazole 33-L and 1-aminoethyltetrazole 32a-L. Each compound was tested initially as the alanyl-X dipeptide form. While most of the alanine bioisosteres were known structures, their novel peptide derivatives required synthetic development using both solution and solid phase techniques. The solid phase synthesis of several C-terminal 1aminoethyltetrazole peptides was successfully established by using 2-chlorotrityl chloride resin. The investigation of the antimicrobial activity of the synthesised compounds identified several clinically applicable selective inhibitors. These compounds were shown to provide differentiation between Salmonella and Escherichia coli, or enterococci and streptococci. This work also gave a useful comparison between the different alanine bioisosteres, and showed the importance of di- and oligopeptide permease systems in order to reach sufficient bacterial activity. The microbiological activity of 1- aminoethyltetrazole peptide derivatives was studied in more detail, due to their potential in clinical applications for the diagnosis of food poisoning. In other work, also directed towards the rapid and selective detection and identification of pathogenic bacteria in a clinical environment, new chromogenic substrates were prepared. Each of these compounds contained a chromogen with a phenoxazin-3-one scaffold linked to an amino acid residue. The purpose of the amino acid is to act as a unit recognised and cleaved by specific hydrolytic bacterial enzymes. Upon liberation, electronic differences between the conjugated and free forms of the chromogen resulted in the development of distinct colour changes, which provide the basis of 4 bacterial detection and identification. Synthetic methods have been developed for the efficient and economical production of this series of substrates. After preparation, these compounds were tested against a panel of clinically relevant bacteria. The aim of these substrates was to present an alternative substrate for (N-β-alanyl)-7-amino-1-pentylphenoxazine-3-one 86a, which is applied commercially in chromID® Pseudomonas aeruginosa chromogenic medium designed for the clinical detection of P.aeruginosa. The new substrates are designed to fully explore the chemical space of phenoxazinonebased chromogenic substrates, and to decrease the colour, as substrate 86a causes significant background colour in culture media. The future application of these substrates in chromogenic media resides in their potential to advance the identification of specific pathogenic bacteria and to thus facilitate the treatment of bacterial infections.

Amorphous solid dispersion (ASD) of a poorly soluble active pharmaceutical ingredient (API) in a polymeric matrix is a promising approach to increase the solubility, dissolution rate and hence bioavailability of the API. From an industrial point of view, spray-drying represents the main solvent evaporation process used for the manufacture of solid dispersions. The aim of the present PhD thesis was to evaluate the accuracy of: i) thermodynamic models (e.g. solubility parameter and Flory-Huggins theories), ii) standard screening methodologies (e.g. solvent casting and quench cooling) and iii) novel screening approaches for predicting the miscibility of binary spray-dried solid dispersions (SDSDs) so that the best performing API-polymer systems at adequate drug-loading (DL) can be selected. Two novel approaches for screening improvement, miniaturization and downscaling of regular spray-drying, were investigated and applied to API-polymer systems consisting of models drugs (Ibuprofen, Naproxen, Carbamazepine and Itraconazole) and seven polymers at four DLs. Screened samples were characterized using modulated differential scanning calorimetry (mDSC), X-ray powder diffraction (XRPD), thermo-gravimetric analysis (TGA) and scanning electron microscopy (SEM). Results obtained from miscibility and solid state characterization were compiled into principal components analysis (PCA) in order to qualitatively rank the screening approaches based upon their prediction accuracy. Non-sink dissolutions conditions with regard to the crystalline API were performed to assess the solubility enhancement and the extent of supersaturation of screened samples. The two proposed screening approaches were found to provide a greater accuracy than traditional screening methodologies to predict the miscibility of SDSDs. The limitations of theoretical models and standard screening methods tested are symptomatic of the gap existing between equilibrium solid solubility to kinetic miscibility as well as the importance of the preparation method with regard to ASD properties. Therefore, the main benefits of the novel approaches rely on their capacity to better reproduce the operating mode and process conditions of regular spray-dryer, while minimizing API needs for a production, significantly. The outcome of this work favours the downscaling approach due to its improved ability to ease the transfer from screening phases to manufacturing stage in the selection of adequate polymer and DL. In this regard, a novel three-stage decision protocol that implements spray-drying in a methodical small-scale approach for the development of ASDs during preclinical activities was developed and has successfully replaced all former practices in UCB projects.

Background: Influenza-like illness (ILI) and asthma are common diagnoses in the general practice and exert considerable morbidity and mortality worldwide. One potentially important strategy to reduce this is to determine whether commonly prescribed drugs modify the occurrence and outcomes of respiratory diseases including mortality. The benzodiazepines, a class of psychoactive drugs generally used in the treatment of anxiety and sleep disorders, have recently been suggested as having detrimental effects on immune response to infection, predisposing its users to increased risk of infection and mortality. These drugs have also been implicated in the pathogenesis of asthma. This thesis therefore aimed to investigate whether benzodiazepines modify the occurrence of asthma exacerbation and subsequent mortality in patients with asthma as well as ILI-related pneumonia and ILI-related mortality in patients with ILI. Methods: The Clinical Practice Research Datalink (CPRD) was used as the data source. CPRD contains the medical records of over 13 million patients prospectively collected from over 600 general practices across the United Kingdom and has linkages to the Hospital Episode Statistics database [HES] and national death registry data (the Office of National Statistics [ONS]) which were utilised in this study. CPRD-HES linked data was used to validate diagnoses of asthma exacerbation whereas ONS mortality data validated deaths identified from CPRD. Case-control and cohort study designs were used to investigate associations between benzodiazepines and the occurrence of asthma exacerbation, ILI-related pneumonia and mortality. Results: After adjusting for a wide range of potential confounders including physical and psychiatric comorbidities, and concurrent use of other drugs, exposure to benzodiazepines was associated with statistically significant increased occurrence of asthma exacerbation, ILI-related pneumonia and mortality. These associations were observed with both short term and chronic benzodiazepines use. However, the effect of individual benzodiazepines varied across the outcomes of interest with some of the associations lacking statistical significance. For instance, current use of diazepam and temazepam but not lorazepam showed statistically significant associations with increased occurrence of asthma exacerbation. Conclusion: Overall, findings of this research signal an adverse benzodiazepine effect and hence suggest that a precautionary approach should be exercised when prescribing benzodiazepines in the interim before conclusive evidence is yielded by further research, especially in patients who may already be at increased risk of asthma exacerbation or pneumonia and mortality.

No description available.

No description available.

No description available.

No description available.

No description available.

<p>Many blood cell mechanisms in the human body are working all the time to maintain haemostasis in the blood vessels. Once a wound arises platelets are alerted via different substances to cover the wound and prevent loss of blood. Most of the times these mechanisms do stop the blood, and further heal the wound. During other circumstances the platelet-covering continues to form a thrombus, preventing the blood to flow and instead causes myocardial infarction or stroke. There are several risk factors triggering development of circulatory diseases such as obesity, lack of exercise, smoking, infection and stress.</p><p>This thesis describes the interaction between the two platelet thrombin receptors PAR1 and PAR4, together with the interaction of the oral pathogen <em>Porphyromonas gingivalis</em> (with thrombin-like gingipains), and the cross talk with the stress hormone epinephrine and its α_2A adrenergic receptor. Until now PAR1 is thought to be the most important thrombin receptor due to its high affinity for thrombin. From a phylogenetical and patophysiological point of view there must be a reason why platelets express two different thrombin receptors. Today PAR4 is considered less important, but this thesis implies that PAR4 plays an important role in platelet signaling and haemostasis.</p><p>The results show that bacteria pre-stimulated platelets, followed by epinephrine gives a strong and full aggregation and calcium mobilization, in both aspirinated and non-aspirinated human platelets. The amount of bacteria does not itself, or epinephrine alone give aggregation or calcium mobilization. This mechanism is dependent on both Rgp type gingipain released from <em>P. gingivalis</em>, and PARs in an interaction with the α_2A adrenergic receptor.</p><p>Further, results reveal that PAR4 interacts and cross talks with the platelet α_2A-adrenergic receptor in <em>aspirinated </em>platelets. Neither of the two platelet purinergic P2Y-receptors (P2Y₁₂ and P2Y₁) contribute to this action, but the purinergic P2X₁ does. In aggregation studies a low dose of PAR4 activating peptide (AP), but not PAR1-AP, followed by epinephrine results in a strong aggregation and in a calcium mobilization. ATP secretion measurements did reveal that ATP was released during epinephrine stimulation, which indicate that ATP and P2X₁ have a key role in this event. By blocking P2X₁ both aggregation and calcium mobilization were abolished, but not by blocking P2Y₁₂ and P2Y₁. Inhibition of PI3-kinase, both epinephrine-induced calcium mobilization and aggregation were significant reduced. In <em>non-aspirinated</em> platelets PAR1 synergizes with the α_2A adrenergic receptor and P2X₁.</p><p>In conclusion, this thesis suggests that PAR4 plays an intriguing and important role in platelets with inactived cyclooxygenase 1.  The results described in this thesis contribute to an increased knowledge of the platelet thrombin receptors.</p>