Quaternary ammonium chitosans: The importance of the positive fixed charge of the drug delivery systems

As a natural polysaccharide, chitosan has good biocompatibility, biodegradability and biosecurity. The hydroxyl and amino groups present in its structure make it an extremely versatile and chemically modifiable material. In recent years, various synthetic strategies have been used to modify chitosan, mainly to solve the problem of its insolubility in neutral physiological fluids. Thus, derivatives with negative or positive fixed charge were synthesized and used to prepare innovative drug delivery systems. Positively charged conjugates showed improved properties compared to unmodified chitosan. In this review the main quaternary ammonium derivatives of chitosan will be considered, their preparation and their applications will be described to evaluate the impact of the positive fixed charge on the improvement of the properties of the drug delivery systems based on these polymers. Furthermore, the performances of the proposed systems resulting from in vitro and ex vivo experiments will be taken into consideration, with particular attention to cytotoxicity of systems, and their ability to promote drug absorption

Bose-Einstein Condensation of Helium and Hydrogen inside Bundles of Carbon Nanotubes

Helium atoms or hydrogen molecules are believed to be strongly bound within the interstitial channels (between three carbon nanotubes) within a bundle of many nanotubes. The effects on adsorption of a nonuniform distribution of tubes are evaluated. The energy of a single particle state is the sum of a discrete transverse energy Et (that depends on the radii of neighboring tubes) and a quasicontinuous energy Ez of relatively free motion parallel to the axis of the tubes. At low temperature, the particles occupy the lowest energy states, the focus of this study. The transverse energy attains a global minimum value (Et=Emin) for radii near Rmin=9.95 Ang. for H2 and 8.48 Ang.for He-4. The density of states N(E) near the lowest energy is found to vary linearly above this threshold value, i.e. N(E) is proportional to (E-Emin). As a result, there occurs a Bose-Einstein condensation of the molecules into the channel with the lowest transverse energy. The transition is characterized approximately as that of a four dimensional gas, neglecting the interactions between the adsorbed particles. The phenomenon is observable, in principle, from a singular heat capacity. The existence of this transition depends on the sample having a relatively broad distribution of radii values that include some near Rmin.Comment: 21 pages, 9 figure

Jellyfish Polysaccharides for Wound Healing Applications

Jellyfishes are considered a new potential resource in food, pharmaceutical and biomedical industries. In these latter cases, they are studied as source of active principles but are also exploited to produce marine collagen. In the present work, jellyfish skin polysaccharides (JSP) with glycosaminoglycan (GAG) features were extracted from Rhizostoma pulmo, a main blooming species of Mediterranean Sea, massively augmented by climate leaded “jellyfishication” of the sea. Two main fractions of R. pulmo JSP (RP-JSPs) were isolated and characterized, namely a neutral fraction (RP-JSP1) and a sulphate rich, negatively charged fraction (RP-JSP2). The two fractions have average molecular weights of 121 kDa and 590 kDa, respectively. Their sugar composition was evaluated through LC-MS analysis and the result confirmed the presence of typical GAG saccharides, such as glucose, galactose, glucosamine and galactosamine. Their use as promoters of wound healing was evaluated through in vitro scratch assay on murine fibroblast cell line (BALB/3T3 clone A31) and human keratinocytes (HaCaT). Both RP-JSPs demonstrated an effective confluency rate activity leading to 80% of scratch repair in two days, promoting both cell migration and proliferation. Additionally, RP-JSPs exerted a substantial protection from oxidative stress, resulting in improved viability of treated fibroblasts exposed to H2O2. The isolated GAG-like polysaccharides appear promising as functional component for biomedical skin treatments, as well as for future exploitation as pharmaceutical excipients

Thiolated 2-Methyl-β-Cyclodextrin as a Mucoadhesive Excipient for Poorly Soluble Drugs: Synthesis and Characterization

Thiolated cyclodextrins are structurally simple mucoadhesive macromolecules, which are able to host drugs and increase their apparent water solubility, as well as interact with the mucus layer prolonging drug residence time on the site of absorption. The aim of this study was to synthesize through green microwave-assisted process a freely soluble thiolated 2-methyl-β-cyclodextrin (MβCD-SH). Its inclusion complex properties with dexamethasone (Dex), a poor water soluble drug, and mucoadhesive characteristics were also determined. The product was deeply characterized through NMR spectroscopy (2D COSY, 2D HSQC, 1D/2D TOCSY, and 1D ROESY), showing a thiolation degree of 67%, a selective thiolation on the C6 residues and a monomeric structure. The association constant of MβCD and MβCD-SH with Dex resulted in 2514.3 ± 32.3 M−1 and 2147.0 ± 69.3 M−1, respectively, indicating that both CDs were able to host the drug. Microrheological analysis of mucin in the presence of MBCD-SH showed an increase of complex viscosity, G′ and G′′, due to disulphide bond formation. The cytotoxicity screening on fibroblast BALB/3T3 clone A31 cells indicated an IC50 of 27.7 mg/mL and 30.0 mg/mL, for MβCD and MβCD-SH, respectively. Finally, MβCD-SH was able to self-assemble in water into nanometric structures, both in the presence and absence of the complexed drug

Threshold criterion for wetting at the triple point

Grand canonical simulations are used to calculate adsorption isotherms of various classical gases on alkali metal and Mg surfaces. Ab initio adsorption potentials and Lennard-Jones gas-gas interactions are used. Depending on the system, the resulting behavior can be nonwetting for all temperatures studied, complete wetting, or (in the intermediate case) exhibit a wetting transition. An unusual variety of wetting transitions at the triple point is found in the case of a specific adsorption potential of intermediate strength. The general threshold for wetting near the triple point is found to be close to that predicted with a heuristic model of Cheng et al. This same conclusion was drawn in a recent experimental and simulation study of Ar on CO_2 by Mistura et al. These results imply that a dimensionless wetting parameter w is useful for predicting whether wetting behavior is present at and above the triple temperature. The nonwetting/wetting crossover value found here is w circa 3.3.Comment: 15 pages, 8 figure

TL1A/DR3 axis involvement in the inflammatory cytokine network during pulmonary sarcoidosis

BACKGROUND: TNF-like ligand 1A (TL1A), a recently recognized member of the TNF superfamily, and its death domain receptor 3 (DR3), firstly identified for their relevant role in T lymphocyte homeostasis, are now well-known mediators of several immune-inflammatory diseases, ranging from rheumatoid arthritis to inflammatory bowel diseases to psoriasis, whereas no data are available on their involvement in sarcoidosis, a multisystemic granulomatous disease where a deregulated T helper (Th)1/Th17 response takes place. METHODS: In this study, by flow cytometry, real-time PCR, confocal microscopy and immunohistochemistry analyses, TL1A and DR3 were investigated in the pulmonary cells and the peripheral blood of 43 patients affected by sarcoidosis in different phases of the disease (29 patients with active sarcoidosis, 14 with the inactive form) and in 8 control subjects. RESULTS: Our results demonstrated a significant higher expression, both at protein and mRNA levels, of TL1A and DR3 in pulmonary T cells and alveolar macrophages of patients with active sarcoidosis as compared to patients with the inactive form of the disease and to controls. In patients with sarcoidosis TL1A was strongly more expressed in the lung than the blood, i.e., at the site of the involved organ. Additionally, zymography assays showed that TL1A is able to increase the production of matrix metalloproteinase 9 by sarcoid alveolar macrophages characterized, in patients with the active form of the disease, by reduced mRNA levels of the tissue inhibitor of metalloproteinase (TIMP)-1. CONCLUSIONS: These data suggest that TL1A/DR3 interactions are part of the extended and complex immune-inflammatory network that characterizes sarcoidosis during its active phase and may contribute to the pathogenesis and to the progression of the disease

SARS-CoV-2 infection in beta thalassemia: Preliminary data from the Italian experience

Patients with pre\u2010existent chronic morbidities are likely to be more severely affected by SARS\u2010Cov2 infection, but no data are available regarding Thalassemic Syndromes (TS). Note, TS and hemoglobin variants represent, according to WHO, one of the most frequent causes of anemia, affecting more than 7% of the world population.1 Thalassemic Syndromes are classified in either transfusion\u2010dependent thalassemia (TDT) or non\u2010transfusion\u2010dependent thalassemia (NTDT). Infectious complications, mainly from bacteria, constitute a common cause of mortality and morbidity in TS. Stress erythropoiesis, iron overload, splenectomy and adrenal insufficiency among others may contribute to increase susceptibility to infection.2 To verify the impact of SARS\u2010CoV\u20102 infection on TS, we set\u2010up a specific survey by electronic Case Report Form (eCRF).3 Inclusion criteria require at least 15\u2009days of follow\u2010up from either the onset of symptoms or SARS\u2010CoV2 positivity. The survey was approved by Ethics Committee and eCRF was shared with the Centers of Italian Hemoglobinopathies Network. The \u201cSociet\ue0 Italiana Talassemie ed Emoglobinopatie\u201d (SITE), has estimated the presence in Italy of approximately 5000 TDT and 1900 NTDT patients.3 As of 10 April 2020, 11 cases of TS and COVID\u201019 have been collected (see supplementary information). All the reported patients are in Northern Italy, where the rate of infection is higher, reflecting the national epidemiology. The mean age is 44\u2009\ub1\u200911\u2009years (range 31\u201061\u2009years) and 55% (6/11) are females. Ten patients are TDT, and one is NTDT. All the patients have thalassemia associated comorbidities, eight are splenectomized, and one patient (#9 in the supplementary table) has pulmonary hypertension treated with sildenafil. The likely source of infection has been detected in 55% (6/11) of cases: two had contacts with COVID\u201019 positive subjects, and four had occupational exposure (three are nurses working in hospital or assisted living facilities). Three patients were asymptomatic. One patient (#3 in supplementary information) was admitted for high fever and bone marrow hypoplasia, lymphopenia, and agranulocytosis (on treatment with deferiprone) and tested positive at the third swab. Six out of 11 were hospitalized, but no one required mechanical ventilation. The patient with more severe symptoms who required more intensive ventilation support with continuous positive airway pressure (CPAP) has a history of diffuse large B\u2010cell lymphoma, treated with chemotherapy in the previous year, currently in complete remission. Of the six people admitted to the hospital, only three received supposedly specific treatment for COVID\u201019: one hydroxychloroquine (HCQ), one HCQ plus ritonavir/darunavir, and one HCQ plus anakinra. Patient #3 did not receive HCQ due to concomitant therapy with amiodarone and an increased risk of life\u2010threatening arrhythmia. The clinical course ranged from 10 to 29\u2009days. Ten patients have clinically recovered and are on a daily remote phone call follow\u2010up. Splenectomy which was present in 8/11 patients did not seem to affect the clinical course. Of note, except for the patient with myelosuppression, no increase in blood requirement was observed. When luspatercept treatment was halted in the NTDT patient, hemoglobin fell from 110 to 82 g/L, a value similar to the pre\u2010luspatercept period. Neither death nor severe SARS or signs of cytokines storm were observed in these 11 subjects, which may be surprising, taking into account the mean age and the presence of severe comorbidities. Our data, although preliminary, do not indicate increased severity of COVID\u201019 in TS. A larger number of cases needs to be collected to define the impact of this new infection and its outcome in these fragile patients