Secretion of Sparfloxacin from the Human Intestinal Caco-2 Cell Line Is Altered by P-Glycoprotein Inhibitors

The mechanism of intestinal secretion of the difluorinated quinolone sparfloxacin was investigated with the epithelial cell line Caco-2 and was compared to that of the P-glycoprotein (P-gp) substrate vinblastine. The P-gp inhibitors verapamil and progesterone significantly increased the epithelial cell accumulation of both vinblastine and sparfloxacin. This increase is likely to result from an inhibition of drug secretion since both vinblastine uptake and sparfloxacin uptake are known to proceed through a passive transmembrane diffusion. The unidirectional fluxes across cell monlayers grown on permeable filters indicated that a net secretion of sparfloxacin and vinblastine occurred across Caco-2 cells. These secretions were significantly inhibited by the MDR-reversing agent verapamil. We conclude that the P-gp is likely to be involved in the intestinal elimination of the difluorinated quinolone sparfloxacin.     

Ferritin heavy/light chain (FTH1/FTL) expression,serum ferritin levels,and their functional as well as prognostic roles in acute myeloid leukemia

Spontaneous remission (SR) of acute myeloid leukemia (AML) represents a rare phenomenon and is usually of short duration although long‐term remissions are reported. Indeed, mechanisms underlying SR remain unclear, but it is suggested that immunactivation, e.g. caused by infections, plays an important role. Here we report on a patient who suffered from pneumonia and simultaneously experienced very late hematologic AML relapse seventeen years after allogeneic blood stem cell transplantation (allo‐BSCT). Surprisingly in parallel to recovery from pneumonia peripheral blood count which previously showed pancytopenia, had normalized and bone marrow (BM) aspiration revealed spontaneous remission of AML. To the best of our knowledge we here report on the latest AML relapse after allo‐BSCT experiencing SR.     

Polychlorinated biphenyls (PCBs) modulate both phagocytosis and NK cell activity in vitro in juvenile loggerhead sea turtles (Caretta caretta)

Threatened loggerhead sea turtles (Caretta caretta) face numerous environmental challenges, including exposure to anthropogenic chemicals such as polychlorinated biphenyls (PCBs). Despite being banned by the USA in the 1970s, PCBs persist in the environment and produce immunotoxic effects in a wide range of marine vertebrate species. This is of particular concern, as the modulation of the immune system may enhance the susceptibility to a variety of pathogens. Blood samples were collected from 19 immature, captive-reared loggerhead sea turtles. Functional immune assays phagocytosis and natural killer (NK) cell activity were used to quantify the direct effects of PCB congeners 105, 138, and 169 on innate immune functions upon in vitro exposure of sea turtle cells to increasing concentrations (control (0), 0.5, 1, 2.5, 5, 10, 15, or 20 ppm) of each PCB. PCB 105 significantly elevated eosinophil phagocytosis at 10 and 15 ppm and PCB 138 at 15 ppm compared to unexposed (0 ppm). The effects of PCB 169 on phagocytosis were not evaluated. PCB 138 and 105 significantly decreased NK cell activity at 15 and 20 ppm, compared to unexposed (0 ppm) controls. PCB 169 did not markedly modulate NK activity. This constitutes the first study to investigate the in vitro effects of these three PCBs on sea turtle innate immune functions. These results add to our understanding of PCB-induced immunotoxicity in sea turtles and may provide a framework for establishing the relationships between chemical levels and turtle immunity.     

Asbestos in the sputum, crackles in the lungs, and radiologic changes in women exposed to asbestos

In a rural community in South Africa historically exposed to asbestos environmentally and occupationally, 200 women who had worked with asbestos and applied for medical examination to determine compensable asbestos disease were evaluated. Clinical and radiologic evaluation, sputum collection, and microscopic analysis were done. A questionnaire elicited type of exposure, duration, decade of first work exposure, and environmental exposure. Crackles were present in the lungs of 166 women and asbestos fibers and ferruginous bodies were present in 122. Asbestosis was identified in 26 and plural plaques in 62. Auscultation for crackles (rales) is useful in the initial examination of former asbestos workers in rural communities of developing countries.     

Novel long-circulating liposomes containing peptide library-lipid conjugates: synthesis and in vivo behavior

Rapid uptake of intravenously injected liposomes by the mononuclear phagocyte system has limited their use as drug delivery vehicles. Recently, various long-circulating liposomes have been prepared by incorporating glycolipids or other amphiphilic molecules into the lipid bilayer of conventional liposomes. The purpose of the present study was to design a new class of biodegradable membrane modifiers that would increase the half-life of liposomes in vivo. Using solid-phase peptide synthesis, synthesized were 30-residue random libraries consisting of a random sequence of glycine, beta-alanine and gamma-aminobutyric acid. The libraries were coupled to stearic acid (SA) or phosphatidylethanolamine (PE). The resulting amphiphilic conjugates were mixed with egg phosphatidylcholine (PC) and cholesterol (Chol) in a 6:47:47 ratio, and unilamellar liposomes were prepared. For comparison, plain PC/Chol (50:50) liposomes, as well as liposomes containing polyethylene glycol (PEG)-SA/PC/Chol (6:47:47) and PEG-PE/PC/Chol (6:47:47) were also prepared. Calcein was entrapped in the liposomes, which were given intravenously to rats at a dose of 9.2 mumol lipid/kg, and the amount of intact liposomes present in serum was followed with time. While the conventional liposomes had a short elimination half-life (28 min), the liposomes modified with library-PE had a much longer half-life (170 min), while library-SA provided no improvement of the liposome pharmacokinetics. PEG-PE greatly improved the half-life of the liposomes (400 min) while PEG-SA only provided a marginal improvement. All liposome preparations were cleared in a biphasic fashion. In conclusion, a novel biodegradable lipopeptide conjugate was designed that endows liposomes with a prolonged circulation time in vivo. The pharmacokinetic profile of these modified liposomes was drastically improved over that of conventional liposomes. Since the library is prepared by solid-phase synthesis, length and/or composition could easily be modified in order to modulate the clearance profile of the liposomes. Tailoring of the pharmacokinetic profile of the liposomes depending on their intended application may allow for a greater flexibility of use than PEG-PE.     

Geographical Patterns in Cyanobacteria Distribution: Climate Influence at Regional Scale

Cyanobacteria are a component of public health hazards in freshwater environments because of their potential as toxin producers. Eutrophication has long been considered the main cause of cyanobacteria outbreak and proliferation, whereas many studies emphasized the effect of abiotic parameters (mainly temperature and light) on cell growth rate or toxin production. In view of the growing concerns of global change consequences on public health parameters, this study attempts to enlighten climate influence on cyanobacteria at regional scale in Brittany (NW France). The results show that homogeneous cyanobacteria groups are associated with climatic domains related to temperature, global radiation and pluviometry, whereas microcystins (MCs) occurrences are only correlated to local cyanobacteria species composition. As the regional climatic gradient amplitude is similar to the projected climate evolution on a 30-year timespan, a comparison between the present NW and SE situations was used to extrapolate the evolution of geographical cyanobacteria distribution in Brittany. Cyanobacteria composition should shift toward species associated with more frequent Microcystins occurrences along a NW/SE axis whereas lakes situated along a SW/NE axis should transition to species (mainly Nostocales) associated with lower MCs detection frequencies.     

Comparison between a new multiplex electrochemiluminescence assay and the WHO reference enzyme-linked immunosorbent assay to measure serum antibodies against pneumococcal serotype-specific polysaccharides

Background

Two electrochemiluminescence (ECL) assays were developed which, together, can simultaneously measure serum antibodies against pneumococcal capsular polysaccharides (PnPS) for 17 serotypes. The assays were validated for the 13 PnPS included in the 13-valent pneumococcal conjugate vaccine (PCV13). As recommended by the World Health Organization (WHO), we compared the ECL assays with the WHO reference enzyme-linked immunosorbent assay (ELISA) and derived a threshold corresponding to the 0.35?µg/mL threshold established for the WHO reference ELISA for the non-inferiority comparison and licensure of new PCVs against invasive pneumococcal disease.

Iron Overload Exacerbates Busulfan-Melphalan Toxicity Through a Pharmacodynamic Interaction in Mice

Purpose

Busulfan-melphalan high-dose chemotherapy followed by autologous stem cell transplantation is an essential consolidation treatment of high-risk neuroblastoma in children. Main treatment limitation is hepatic veno-occlusive disease, the most severe and frequent extra-hematological toxicity. This life threatening toxicity has been related to a drug interaction between busulfan and melphalan which might be increased by prior disturbance of iron homeostasis, i.e. an increased plasma ferritin level.

Methods

We performed an experimental study of busulfan and melphalan pharmacodynamic and pharmacokinetics in iron overloaded mice.

Results

Iron excess dramatically increased the toxicity of melphalan or busulfan melphalan combination in mice but it did not modify the clearance of either busulfan or melphalan. We show that prior busulfan treatment impairs the clearance of melphalan. This clearance alteration was exacerbated in iron overloaded mice demonstrating a pharmacokinetic interaction. Additionally, iron overload increased melphalan toxicity without altering its pharmacokinetics, suggesting a pharmacodynamic interaction between iron and melphalan. Based on iron homeostasis disturbance, we postulated that prior induction of ferritin, through Nrf2 activation after oxidative stress, may be associated with the alteration of melphalan metabolism.

Conclusion

Iron overload increases melphalan and busulfan-melphalan toxicity through a pharmacodynamic interaction and reveals a pharmacokinetic drug interaction between busulfan and melphalan.

     

Discovery of indoles as potent and selective inhibitors of the deacetylase SIRT1

High-throughput screening against the human sirtuin SIRT1 led to the discovery of a series of indoles as potent inhibitors that are selective for SIRT1 over other deacetylases and NAD-processing enzymes. The most potent compounds described herein inhibit SIRT1 with IC50 values of 60-100 nM, representing a 500-fold improvement over previously reported SIRT inhibitors. Preparation of enantiomerically pure indole derivatives allowed for their characterization in vitro and in vivo. Kinetic analyses suggest that these inhibitors bind after the release of nicotinamide from the enzyme and prevent the release of deacetylated peptide and O-acetyl-ADP-ribose, the products of enzyme-catalyzed deacetylation. These SIRT1 inhibitors are low molecular weight, cell-permeable, orally bioavailable, and metabolically stable. These compounds provide chemical tools to study the biology of SIRT1 and to explore therapeutic uses for SIRT1 inhibitors.