328 research outputs found

    PLA- and PCL-based Pd(II)-Pyridine Macrocomplexes

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    Chemotherapy of Metastatic Renal Adenocarcinoma with a Five- Drug Regimen*

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    In the past, chemotherapy of renal adenocarcinoma has been relatively unsuccessful. The progestational agent, medroxy progesterone acetate (MPA), has been the most effective single agent, even though the response rate probably does not exceed 12%. This report describes the results of a program of combination therapy with MPA, cyclophosphamide, hydroxyurea, vinblastine and prednisone that was used on 42 patients, ten of whom had received prior MPA therapy. One complete remission and seven partial remissions were observed, oniyone of whom had received prior MPA therapy. Treatment of metastatic renal adenocarcinoma with combination chemotherapy should probably include MPA and adriamycin. The role of estrogen receptor (ER) and progesterone receptor (PR) as predictions of response to hormonal therapy in this disease looks encouraging, but the results reported to date have been limited

    Deep control of linear oligomerization of glycerol using lanthanum catalyst on mesoporous silica gel

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    The valorization of glycerol (1), a waste of biodiesel production of Fatty Acid Methyl Esters (FAMEs), adopting a ā€œgreenā€ approach, represents an important goal of sustainable chemistry. While the polymerization of 1 to hyperbranched oligomers is a well-established process, the linear analogues are difficult to obtain. In this context, we explore the reaction without the solvent of heterogeneous hybrid La(III)O-KIT-6 catalyst (2), which is based on lanthanum oxide on mesoporous silica gel, showing a superior linear selectivity compared to most of the analogous catalysts recently reported

    In conditions of limited chromophore supply rods entrap 11-cis-retinal leading to loss of cone function and cell death

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    RPE65 is a retinoid isomerase required for the production of 11-cis-retinal, the chromophore of both cone and rod visual pigments. We recently established an R91W knock-in mouse strain as homologous animal model for patients afflicted by this mutation in RPE65. These mice have impaired vision and can only synthesize minute amounts of 11-cis-retinal. Here, we investigated the consequences of this chromophore insufficiency on cone function and pathophysiology. We found that the R91W mutation caused cone opsin mislocalization and progressive geographic cone atrophy. Remnant visual function was mostly mediated by rods. Ablation of rod opsin corrected the localization of cone opsin and improved cone retinal function. Thus, our analyses indicate that under conditions of limited chromophore supply rods and cones compete for 11-cis-retinal that derives from regeneration pathway(s) which are reliant on RPE65. Due to their higher number and the instability of cone opsin, rods are privileged under this condition while cones suffer chromophore deficiency and degenerate. These findings reinforce the notion that in patients any effective gene therapy with RPE65 needs to target the cone-rich macula directly to locally restore the cones' chromophore supply outside the reach of rod

    Well-width dependence of exciton-phonon scattering in InxGa1 - xAs/GaAs single quantum wells

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    The temperature and density dependencies of the exciton dephasing time in In0.18Ga0.82As/GaAs single quantum wells with different thicknesses have been measured by degenerate four-wave mixing. The exciton-phonon scattering contribution to the dephasing is isolated by extrapolating the dephasing rate to zero-exciton density. From the temperature dependence of this rate we have deduced the linewidth broadening coefficients for acoustic and optical phonons. We find acoustic-phonon coefficients that increase from 1.6 to 3 Ī¼eV/K when increasing the well width from 1 to 4 nm. This is in quantitative agreement with theoretical predictions when the spatial extension of the exciton wave function, strongly penetrating into the GaAs barrier in thin InxGa1-xAs quantum wells, is taken into account. The optical-phonon coefficient does not show a systematic dependence on well thickness, and is comparable with the value for bulk GaAs

    Mechanistic analysis of massive endocytosis in relation to functionally defined surface membrane domains

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    A large fraction of endocytosis in eukaryotic cells occurs without adaptors or dynamins. Here, we present evidence for the involvement of lipid domains in massive endocytosis (MEND) activated by both large Ca transients and amphipathic compounds in baby hamster kidney and HEK293 cells. First, we demonstrate functional coupling of the two MEND types. Ca transients can strongly facilitate detergent-activated MEND. Conversely, an amphipath with dual alkyl chains, ditridecylphthalate, is without effect in the absence of Ca transients but induces MEND to occur within seconds during Ca transients. Ca transients, like amphipaths, enhance the extraction of lipids from cells by Ī²-cyclodextrins. Second, we demonstrate that electrical and/or optical signals generated by selected membrane probes are nearly insensitive to MEND, suggesting that those probes segregate into membrane domains that are not taken up by MEND. Triphenylphosphoniums are increasingly excluded from domains that internalize as the carbon chain length increases from 4 to 12. The small cationic membrane dye, FM 4ā€“64, binds well to domains that internalize, whereas a closely related dye with a larger hydrophobic moiety, di-4-ANEPPDHQ (ANEPPDHQ) is excluded. Multiple carrier-type ionophores and a small amphipathic anion, niflumic acid, are also excluded. Probes with modest MEND sensitivity include the hydrophobic anion, dipicrylamine, carbonyl cyanide m-chlorophenylhydrazone, and NBD-phosphatidylethanolamine. Third, we demonstrate that large Ca transients can strongly enhance the extracellular binding of several membrane probes, monitored electrically or optically, consistent with a more disordered membrane with more amphipath-binding sites. Fluorescence shifts of ANEPPDHQ report increased disorder of the extracellular monolayer after large Ca transients, consistent with an increased propensity of the membrane to phase separate and vesiculate. Collectively, the results indicate that >50% of the outer monolayer is ordered and can be selectively internalized during MEND responses initiated by two very different cell perturbations

    Are We Sitting Comfortably? Domestic Imaginaries, Laptop Practices, and Energy Use

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    The considerable literature on domestic energy consumption practices has tended to focus on either the (re)production and contestation of normative imaginaries, or the links between escalating standards and energy use. Far less has been written which links these related areas together. Accordingly, this paper is positioned at the intersection of debates on domestic consumption, energy use, and home cultures. Through a qualitative study of laptop use in the home, we illustrate how energy-intensive practices, such as ā€˜always-on-nessā€™, and changing computer ecologies and infrastructures, are intimately bound up with the reproduction of particular domestic imaginaries of family and home. A key insight in this paper is that a purely physiological conception of comfort would fail to explain fully why practices such as always-on-ness emerge, and thus we theorise comfort as an accomplishment comprised of inseparable temporal, bodily, spatial, and material elements. Ultimately, we argue here that comfort needs to be understood as a multivalent imaginary that is itself bound up in broader idealised notions of family and home in order to comprehend shifting practices, computing ecologies, and rising energy consumption

    Single-molecule experiments in biological physics: methods and applications

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    I review single-molecule experiments (SME) in biological physics. Recent technological developments have provided the tools to design and build scientific instruments of high enough sensitivity and precision to manipulate and visualize individual molecules and measure microscopic forces. Using SME it is possible to: manipulate molecules one at a time and measure distributions describing molecular properties; characterize the kinetics of biomolecular reactions and; detect molecular intermediates. SME provide the additional information about thermodynamics and kinetics of biomolecular processes. This complements information obtained in traditional bulk assays. In SME it is also possible to measure small energies and detect large Brownian deviations in biomolecular reactions, thereby offering new methods and systems to scrutinize the basic foundations of statistical mechanics. This review is written at a very introductory level emphasizing the importance of SME to scientists interested in knowing the common playground of ideas and the interdisciplinary topics accessible by these techniques. The review discusses SME from an experimental perspective, first exposing the most common experimental methodologies and later presenting various molecular systems where such techniques have been applied. I briefly discuss experimental techniques such as atomic-force microscopy (AFM), laser optical tweezers (LOT), magnetic tweezers (MT), biomembrane force probe (BFP) and single-molecule fluorescence (SMF). I then present several applications of SME to the study of nucleic acids (DNA, RNA and DNA condensation), proteins (protein-protein interactions, protein folding and molecular motors). Finally, I discuss applications of SME to the study of the nonequilibrium thermodynamics of small systems and the experimental verification of fluctuation theorems. I conclude with a discussion of open questions and future perspectives.Comment: Latex, 60 pages, 12 figures, Topical Review for J. Phys. C (Cond. Matt

    MicroRNA-mediated rescue of fear extinction memory by miR-144-3p in extinction-impaired mice

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    Background MicroRNA (miRNA)-mediated control of gene expression suggests that miRNAs are interesting targets and/or biomarkers in the treatment of anxiety- and trauma-related disorders, where often memory-associated gene expression is adversely affected. Methods The role of miRNAs in the rescue of impaired fear extinction was assessed using the 129S1/SvlmJ (S1) mouse model of impaired fear extinction. miRNA microarray analysis, reverse transcription polymerase chain reaction, fluorescent in situ hybridization, lentiviral overexpression, and Luciferase reporter assays were used to gain insight into the mechanisms underlying miRNA-mediated normalization of deficient fear extinction. Results Rescuing impaired fear extinction via dietary zinc restriction was associated with differential expression of miRNAs in the amygdala. One candidate, miR-144-3p, robustly expressed in the basolateral amygdala, showed specific extinction-induced, but not fear-induced, increased expression in both extinction-rescued S1 mice and extinction-intact C57BL/6 (BL6) mice. miR-144-3p upregulation and effects on subsequent behavioral adaption was assessed in S1 and BL6 mice. miR-144-3p overexpression in the basolateral amygdala rescued impaired fear extinction in S1 mice, led to enhanced fear extinction acquisition in BL6 mice, and furthermore protected against fear renewal in BL6 mice. miR-144-3p targets a number of genes implicated in the control of plasticity-associated signaling cascades, including Pten, Spred1, and Notch1. In functional interaction studies, we revealed that the miR-144-3p target, PTEN, colocalized with miR-144-3p in the basolateral amygdala and showed functional downregulation following successful fear extinction in S1 mice. Conclusions These findings identify a fundamental role of miR-144-3p in the rescue of impaired fear extinction and suggest this miRNA as a viable target in developing novel treatments for posttraumatic stress disorder and related disorders
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