Temperature-sensitive hydrogels

Thermo-sensitive polymers are appealing materials for several therapeutic applications, such as in regenerative medicine and in situ drug release. These macromolecules are characterized by the ability to undergo swelling/deswelling processes during temperature change-induced phase transitions. Swelling and shrinking temperatures depend on the specific physicochemical properties, namely salt concentration or pH, of the thermo-sensitive gels as well as the incubation environment. An understanding of the mechanisms underlying the gel-swelling equilibrium and kinetics is necessary for the selection of an appropriate gel in relation to the specific pharmaceutical application. Thermo-sensitive polymers used in medicine include polyacrylamides, polyvinyls, polyethers, polysaccharides, and polyphosphazenes. A few of them have been successfully used as 3-dimentional supports for cell cultivation, allowing for the production of scaffolds with excellent biologic properties for application in regenerative medicine. Stem cells that can undergo specific differentiation under the appropriate stimulation have also been cultivated. The ability of drug/polymer solutions to turn into gels at physiologic temperature has been exploited for local drug delivery. The prolonged in situ presence and slow drug release enhances the therapeutic performance of antibiotics used in urogenital pathologies, anti-inflammatory agents, and anticancer drugs. The reduced toxicity as well as lower fluctuations in peak-to-trough drug concentrations make these systems superior to traditional gels. Thermo-sensitive hydrogels have also been demonstrated to be interesting formulations for the delivery of biotechnological drugs. Proteins and oligonucleotides can be loaded under mild conditions, stabilized, and released at a controlled rate. Finally, thermo-reversible polymers have been investigated for protein conjugation to enhance the physicochemical, biologic, immunologic, and pharmacokinetic properties of biotechnological products.     

When Fever, Paracetamol? Theory and Practice in a Paediatric Outpatient Clinic

Objective: To determine how medical and nursing staff treat feverish children and compare the findings with their theoretical knowledge, evaluating how they might contribute to fever phobia in parents.Setting: Paediatric Emergency Department.Method: In the first step, we analysed prospectively the files of all children having consulted the Paediatric Emergency Department with a history of fever or of body temperature above 38 °C during a 2-week period. The second step consisted of evaluating knowledge and perception of fever of doctors and nurses using a questionnaire.Main outcome measures: Prospective study: final diagnosis (viral, non- invasive bacterial disorders, invasive bacterial disorders), site of measurement and average temperature. Evaluation of theoretical knowledge: definition of fever, site of measurement, evaluation of the child’s clinical state, antipyretic drug choice.Results: A total of 114 children under 5 years of age were enrolled and 24 caregivers (12 doctors, 12 nurses, 90 of the staff) responded to the questionnaire. The results showed good consistency in theoretical knowledge, but an excessive fear about cerebral damage was also shown by doctors. This belief likely contributes to the transmission of fever phobia to parents. In contrast, analysis of children management showed that fever was often under-treated, especially by nurses and even more so by parents. Paracetamol remained the first-line antipyretic drug yet was often administered in insufficient doses. Non-steroidal anti-inflammatory drugs were seldom used, except by parents (16 of all the children). Contrary to literature, the favourite route of administration was the rectal one. Physical methods like sponging were largely used by nurses, despite the uncertainties in their real effectiveness and their known side-effects.Conclusion: Our study showed that the management of feverish children was globally correct in the Paediatric Emergency Department, but several improvement measures have been taken (e.g. tables of normal and abnormal ranges of temperature, recommended temperature measurement techniques, dosage regimen of antipyretic drugs, guidelines to parents), justifying the implementation of a pharmaceutical follow-up.     

NMR studies of the inclusion complex between β-cyclodextrin and paroxetine

A ¹H and ¹³C NMR study on the inclusion complex of paroxetine with β-cyclodextrin was carried out in order to define the stoichiometry of the association and its strength. Proton and carbon chemical shift measurements of paroxetine and β-cyclodextrin were performed at several molar ratios and temperatures, allowing the determination of a 1:1 stoichiometry and an association constant value of the order of 2 × 10³ for the paroxetine–β-cyclodextrin complex. Overhauser effects in the rotating frame were also measured, and the experimental interproton distance constraints have been used for molecular model building of the complex. The obtained model indicates that the benzodioxolyl moiety of paroxetine is deeply inserted in the cavity of the cylindrical structure of β-cyclodextrin, while the fluoro-phenyl ring lays above the wider rim.     

Proline-rich tyrosine kinase Pyk2 regulates deep vein thrombosis

Deep vein thrombosis results from the cooperative action of leukocytes, platelets, and endothelial cells. The proline-rich tyrosine kinase Pyk2 regulates platelet activation and supports arterial thrombosis. In this study, we combined pharmacological and genetic approaches to unravel the role of Pyk2 in venous thrombosis. We found that mice lacking Pyk2 almost completely failed to develop deep venous thrombi upon partial ligation of the inferior vena cava. Pyk2-deficient platelets displayed impaired exposure of phosphatidylserine and tissue factor expression by endothelial cells and monocytes was completely prevented by inhibition of Pyk2. In human umbilical vein endothelial cells (HUVEC), inhibition of Pyk2 hampered IL-1β-induced expression of VCAM and P-selectin, and von Willebrand factor release. Pyk2-deficient platelets showed defective adhesion on von Willebrand factor and reduced ability to bind activated HUVEC under flow. Moreover, inhibition of Pyk2 in HUVEC strongly reduced platelet adhesion. Similarly, Pyk2-deficient neutrophils were unable to efficiently roll and adhere to immobilized endothelial cells under venous flow conditions. Moreover, platelets and neutrophils from Pyk2-knockout mice showed defective ability to form heterogeneous aggregates upon stimulation, while platelet monocyte interaction occurred normally. Consequently, platelet neutrophil aggregates, abundant in blood of wild-type mice upon inferior vena cava ligation, were virtually undetectable in Pyk2-knockout mice. Finally, we found that expression of Pyk2 was required for NETosis induced by activated platelets. Altogether our results demonstrate a critical role of Pyk2 in the regulation of the coordinated thromboinflammatory responses of endothelial cells, leukocytes and platelets leading to venous thrombosis. Pyk2 may represent a novel promising target in the treatment of deep vein thrombosis.