Characterization and In Vitro Skin Permeation of Meloxicam-Loaded Liposomes versus Transfersomes

The goal of this study was to develop and evaluate the potential use of liposome and transfersome vesicles in the transdermal drug delivery of meloxicam (MX). MX-loaded vesicles were prepared and evaluated for particle size, zeta potential, entrapment efficiency (%EE), loading efficiency, stability, and in vitro skin permeation. The vesicles were spherical in structure, 90 to 140 nm in size, and negatively charged (−23 to −43 mV). The %EE of MX in the vesicles ranged from 40 to 70%. Transfersomes provided a significantly higher skin permeation of MX compared to liposomes. Fourier Transform Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC) analysis indicated that the application of transfersomes significantly disrupted the stratum corneum lipid. Our research suggests that MX-loaded transfersomes can be potentially used as a transdermal drug delivery system

Iontophoresis: Skin Permeation Enhancement and Applications

Transdermal drug delivery (TDD) systems offer a number of potentialadvantages over conventional methods such as injectable and oraldelivery as they avoid the first pass metabolism and increase thepatient’s compliance. However, a major limitation of TDDs is that theskin is highly impermeable to macromolecules and hydrophilic drugs.The main barrier of drugs across the skin is the skin outermost layer,the stratum corneum. Application of electricity via the skin is one ofthe methods extensively used for enhancing drugs or chemicalsubstances through the skin. In this article, iontophoresis, a methodfor enhancing the skin permeation of hydrophilic drugs, macromolecules,and charged substances is reviewed. The article alsoelaborates on mechanisms that iontophoresis enhances skinabsorption which include electromigration, electroosmosis andpassive permeability. Factors affecting TDD systems usingiontophoresis including electric current, physicochemical properties ofdrug and physical properties of the skin are also discussed.Keywords:iontophoresis, skin permeation enhancement, factorsaffecting skin permeatio

Mutations of Francisella novicida that Alter the Mechanism of Its Phagocytosis by Murine Macrophages

Infection with the bacterial pathogen Francisella tularensis tularensis (F. tularensis) causes tularemia, a serious and debilitating disease. Francisella tularensis novicida strain U112 (abbreviated F. novicida), which is closely related to F. tularensis, is pathogenic for mice but not for man, making it an ideal model system for tularemia. Intracellular pathogens like Francisella inhibit the innate immune response, thereby avoiding immune recognition and death of the infected cell. Because activation of inflammatory pathways may lead to cell death, we reasoned that we could identify bacterial genes involved in inhibiting inflammation by isolating mutants that killed infected cells faster than the wild-type parent. We screened a comprehensive transposon library of F. novicida for mutant strains that increased the rate of cell death following infection in J774 macrophage-like cells, as compared to wild-type F. novicida. Mutations in 28 genes were identified as being hypercytotoxic to both J774 and primary macrophages of which 12 were less virulent in a mouse infection model. Surprisingly, we found that F. novicida with mutations in four genes (lpcC, manB, manC and kdtA) were taken up by and killed macrophages at a much higher rate than the parent strain, even upon treatment with cytochalasin D (cytD), a classic inhibitor of macrophage phagocytosis. At least 10-fold more mutant bacteria were internalized by macrophages as compared to the parent strain if the bacteria were first fixed with formaldehyde, suggesting a surface structure is required for the high phagocytosis rate. However, bacteria were required to be viable for macrophage toxicity. The four mutant strains do not make a complete LPS but instead have an exposed lipid A. Interestingly, other mutations that result in an exposed LPS core were not taken up at increased frequency nor did they kill host cells more than the parent. These results suggest an alternative, more efficient macrophage uptake mechanism for Francisella that requires exposure of a specific bacterial surface structure(s) but results in increased cell death following internalization of live bacteria

A Francisella Mutant in Lipid A Carbohydrate Modification Elicits Protective Immunity

Francisella tularensis (Ft) is a highly infectious Gram-negative bacterium and the causative agent of the human disease tularemia. Ft is designated a class A select agent by the Centers for Disease Control and Prevention. Human clinical isolates of Ft produce lipid A of similar structure to Ft subspecies novicida (Fn), a pathogen of mice. We identified three enzymes required for Fn lipid A carbohydrate modifications, specifically the presence of mannose (flmF1), galactosamine (flmF2), or both carbohydrates (flmK). Mutants lacking either galactosamine (flmF2) or galactosamine/mannose (flmK) addition to their lipid A were attenuated in mice by both pulmonary and subcutaneous routes of infection. In addition, aerosolization of the mutants (flmF2 and flmK) provided protection against challenge with wild-type (WT) Fn, whereas subcutaneous administration of only the flmK mutant provided protection from challenge with WT Fn. Furthermore, infection of an alveolar macrophage cell line by the flmK mutant induced higher levels of tumor necrosis factor-α (TNF-α) and macrophage inhibitory protein-2 (MIP-2) when compared to infection with WT Fn. Bone marrow–derived macrophages (BMMø) from Toll-like receptor 4 (TLR4) and TLR2/4 knockout mice infected with the flmK mutant also produced significantly higher amounts of interleukin-6 (IL-6) and MIP-2 than BMMø infected with WT Fn. However, production of IL-6 and MIP-2 was undetectable in BMMø from MyD88−/− mice infected with either strain. MyD88−/− mice were also susceptible to flmK mutant infection. We hypothesize that the ability of the flmK mutant to activate pro-inflammatory cytokine/chemokine production and innate immune responses mediated by the MyD88 signaling pathway may be responsible for its attenuation, leading to the induction of protective immunity by this mutant

In vitro in vivo relations for the parenteral liposomal formulation of Amphotericin B: A biorelevant and clinically relevant approach

There is limited information on how to perform in vitro release tests for intravenously administered parenteral formulations and how to relate the in vitro release with an in vivo pharmacokinetic parameter after the administration of the formulation. In this study, the effect of hydrodynamics (using sample and separate and continuous flow conditions) and medium components (synthetic surfactants, albumin and buffers) on the release of Amphotericin B from the liposomal Ambisome® formulation were investigated. Pharmacokinetic modeling of plasma concentration profiles from healthy subjects administered Ambisome® was used to estimate the in vivo release rate constant of drug from the formulation in order to compare it with the in vitro release profiles. With the estimated in vivo and in vitro release rate constants, release profiles were generated. Two approaches were followed: comparison of in vivo and in vitro release rate constants and comparison of the area under the percent release-time curve from observed in vitro release data and simulated in vivo release data. Albumin was found to be most critical factor for the release of the drug by having a negative effect on the amount of Amphotericin B released. The release profiles obtained with the sample and separate method in both Krebs Ringer buffer- and Phosphate Saline buffer - albumin 4.0% w/v were predictive of the in vivo release profiles in healthy subjects. Determining the factors affecting drug release from parenteral formulations and relating the release profiles to a pharmacokinetic parameter in vivo supports the development of in vitro in vivo relations for parenteral products

Efficiency of genomic selection for tomato fruit quality

Fruit quality is polygenic; each component has variable heritability and is difficult to assess. Genomic selection, which allows the prediction of phenotypes based on the whole-genome genotype, could vastly help to improve fruit quality. The goal of this study is to evaluate the accuracy of genomic selection for several metabolomic and quality traits by cross-validation and to estimate the impact of different factors on its accuracy. We analyzed data from 45 phenotypic traits and genotypic data obtained from a previous study of genetic association on a collection of 163 tomato accessions. We tested the influence of (1) the size of training population, (2) the number and density of molecular markers and (3) individual relatedness on the accuracy of prediction. The prediction accuracy of phenotypic values was largely related to the heritability of the traits. The size of training population increased the accuracy of predictions. Using 122 accessions and 5995 single nucleotide polymorphisms (SNPs) was the optimal condition. The density of markers and their numbers also affected the accuracy of the prediction. Using 2313 SNP markers distributed 0.1 cM or more apart from each other reduced the accuracy of prediction, and no gain in prediction accuracy was found when more markers were used in the model. Additionally, the more accessions were related, the more accurate were the predictions. Finally, the structure of the population negatively affected the prediction accuracy. In conclusion, the results obtained by cross-validation illustrated the effect of several parameters on the accuracy of prediction and revealed the potential of genomic selection in tomato breeding programs

A Serotyping Assay for Hepatitis C Virus in Southeast Asia

ABSTRACT A serotyping assay for hepatitis C virus (HCV) was evaluated with samples from Thailand, where the distribution of HCV genotypes was different from that in Western countries where the assay was designed and validated. The sensitivity of the assay was low (58%) for HCV RNA-positive samples compared to that of the genotyping assay (95%, P &lt; 0.01). In addition, only 36% of anti-HCV-positive but HCV RNA-negative samples could be serotyped. The serotypes and genotypes were identical in 96% of the samples that could be typed by both methods. Most of the samples with genotype 6, which was common in Southeast Asia, were nontypeable by this serotyping assay. </jats:p