Electrospinning scale-up and formulation development of PVA nanofibers aiming oral delivery of biopharmaceuticals

Electrospinning is a promising drying technology providing a rapid and gentle drying at ambient temperature, thus electrospinning of polyvinyl alcohol aqueous solutions was investigated for the solid formulation of biopharmaceuticals. The commonly used single-needle electrospinning does not have adequate productivity to satisfy the industrial requirements, therefore our aim was to study the scale-up of the technology by using high-speed electrospinning. High molecular weight polyethylene oxide as a secondary polymer was applied to enhance the fiber formation of polyvinyl alcohol. While polyvinyl alcohol-polyethylene oxide formulations resulted in adequate fiber formation it was not possible to process them further as the friability of the fibers was too low. In order to increase the friability, the effect of adding various sugars (mannitol, glucose, lactose, saccharose, and trehalose) was investigated. The results showed that mannitol was the best friability enhancing excipient because of its crystallinity and low moisture content in the fibrous sample. In contrast, glucose, lactose, saccharose, and trehalose were amorphous with higher moisture content and fibers containing these were grindable only after post-drying

Molecular Basis of Repolarization Reserve Differences between Dogs and Man

Dog models are often used for clinically related electrophysiology research, but their appropriateness and limitations are unclear. This study compared repolarization reserve and its molecular basis in dogs vs humans. Rapid (IKr) and slow (IKs) delayed rectifier and inward rectifier (IK1) K+ currents were measured in cardiomyocytes from normal dog and human tissue-donor hearts. IK1, IKr and IKs blocking effects on action potential duration (APD) were studied on human and dog papillary muscle preparations. Gene expression was measured by real time PCR. IKr densities were similar in dog and man (0.37\ub10.03 pA/pF vs 0.29\ub10.05 pA/pF, P=ns). IK1 was ~3-fold greater in canine vs human cells (eg at \u201360 mV: 1.72\ub10.07 pA/pF vs 0.65\ub10.1 pA/pF*; n=21\u201328, *P<0.05), and IKs was ~4-fold greater in dog cardiomyocytes (eg at ~40 mV: 0.72\ub10.11 pA/pF vs human 0.18\ub10.03 pA/pF*, n=10\u201315). IK1 inhibition (Ba2+) marginally increased APD in humans (by 4.8 \ub1 1.5 %) but caused larger increases in dogs (17.9 \ub1 2.1 %*). In contrast, IKr inhibition caused remarkable APD prolongation in humans (44 \ub1 4 %) versus dogs (16 \ub1 2 %*). IK1-inhibition potentiated APD-prolonging actions of IKr-blockade more in dogs (APD-increase augmented by 55%) than in humans (APD-increase enhanced by 33%) and IKs-inhibition enhanced APD-prolonging actions of IKr-blockade more in dogs (APD-increase augmented by 20%) than in humans (APD-increase enhanced by 9%), confirming the role of IK1 and IKs in limiting IKr-blocking effects in dogs. Kir2.1 subunit mRNA was significantly more abundant in dog compared to human (by ~4 fold), while Kir2.2, Kir2.3, Kir2.4, the IKr-subunit ERG and Ito-subunits (Kv1.4, Kv4.3 and KChIP2) were expressed at similar levels. One IKs-related gene (KvLQT1) was similarly expressed, while minK was more abundant (~ 7-fold) in dogs than humans. Smaller IK1 and IKs, possibly due to differential expression of the IK1 \u3b2-subunit Kir2.1 and the IKs \u3b2-subunit minK, limit repolarization reserve and exaggerate APD-prolongation by IKr-block in humans compared to dogs. These findings provide insights into species-specific determinants of responses to repolarization stress and are relevant to relating findings in dog studies to clinical phenomena in man

Altered expression of genes for Kir ion channels in dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a multifactorial disease characterized by left ventricular dilation that is associated with systolic dysfunction and increased action potential duration. The Kir2.x K+ channels (encoded by KCNJ genes) regulate the inward rectifier current (IK1) contributing to the final repolarization in cardiac muscle. Here, we describe the transitions in the gene expression profiles of 4 KCNJ genes from healthy or dilated cardiomyopathic human hearts. In the healthy adult ventricles, KCNJ2, KCNJ12, and KCNJ4 (Kir2.1–2.3, respectively) genes were expressed at high levels, while expression of the KCNJ14 (Kir2.4) gene was low. In DCM ventricles, the levels of Kir2.1 and Kir2.3 were upregulated, but those of Kir2.2 channels were downregulated. Additionally, the expression of the DLG1 gene coding for the synapse-associated protein 97 (SAP97) anchoring molecule exhibited a 2-fold decline with increasing age in normal hearts, and it was robustly downregulated in young DCM patients. These adaptations could offer a new aspect for the explanation of the generally observed physiological and molecular alterations found in DCM. | La cardiomyopathie dilatée (CMD) est une maladie multifactorielle caractérisée par une dilatation du ventricule gauche associée a` une dysfonction systolique et a` une augmentation de la durée du potentiel d'action. Les canaux potassiques Kir2.x (codés par les gènes KCNJ) régulent le courant rectifiant entrant (IKI), contribuant a` la repolarisation finale du muscle cardiaque. Nous décrivons ici la transition des profils d'expression génique de quatre KCNJ a` partir du coeur d'individus normaux vers des coeurs cardiomyopathiques dilatés. Les gènes KCNJ2, KCNJ12 et KCNJ4 (Kir2.1–2.3) étaient exprimés a` des niveaux élevés dans les coeurs non malades, alors que l'expression du gène KCNJ14 (Kir2.4) était faible. Les niveaux de Kir2.1 et Kir2.3 étaient régulés a` la hausse dans la CMD mais ceux des canaux Kir2.2 étaient diminués. De plus, l'expression du gène DLG1 qui code la protéine associée au synapse SAP97, une protéine d'ancrage, était diminuée de 2 fois en fonction de l'augmentation de l'âge des individus dont le coeur est normal, et elle était fortement diminuée chez les jeunes patients atteints de CMD. Ces adaptations pourraient offrir un constituer une nouvelle façon d'expliquer les modifications physiologiques et moléculaires généralement observées dans la CMD. [Traduit par la Rédaction