Optical characterization of the impact of 100 keV protons on the optical properties of ZrO2 films prepared by ALD on fused silica substrates.

Atomic layer deposition (ALD)-grown zirconia films underwent irradiation by 100 keV protons at fluences ranging from 1⋅1012 p +/c m 2 through 5⋅1014 p +/c m 2. The induced structural damage was modeled using the stopping and range of ions in matter (SRIM) and compared with the change of the optical properties characterized by ellipsometry, spectrophotometry, and x-ray reflectometry. Proton-induced contamination of the optical surface due to deposition of a carbon-rich layer was determined. Correct estimation of the substrate damage was shown to be critical for reliable evaluation of the optical constants of the irradiated films. The ellipsometric angle Δ is shown to be sensitive to both the presence of the buried damaged zone in the irradiated substrate and the contamination layer on the surface of the samples. The complex chemistry in carbon-doped zirconia accommodating over-stoichiometric oxygen is discussed, along with the impact of the film composition change on the refractive index of the irradiated films.

Plasmodial Hsp40 and Hsp70 chaperones: current and future perspectives.

Plasmodium falciparum displays a large and remarkable variety of heat shock protein 40 family members (PfHsp40s). The majority of the PfHsp40s are poorly characterized, and although the functions of some of them have been suggested, their exact mechanism of action is still elusive and their interacting partners and client proteins are unknown. The P. falciparum heat shock protein 70 family members (PfHsp70s) have been more extensively characterized than the PfHsp40s, with certain members shown to function as molecular chaperones. However, little is known about the PfHsp70-PfHsp40 chaperone partnerships. There is mounting evidence that these chaperones are important not only in protein homoeostasis and cytoprotection, but also in protein trafficking across the parasitophorous vacuole (PV) and into the infected erythrocyte. We propose that certain members of these chaperone families work together to maintain exported proteins in an unfolded state until they reach their final destination. In this review, we critically evaluate what is known and not known about PfHsp40s and PfHsp70s.

The importance of the energetic species in pulsed laser deposition for nanostructuring.

This work reports on the optical and structural properties of nanostructured films formed by Ag nano-objects embedded in amorphous aluminium oxide (a-Al(2)O(3)) prepared by alternate pulsed laser deposition (PLD). The aim is to understand the importance of the energetic species involved in the PLD process for nanostructuring, i.e. for organizing nanoparticles (NPs) in layers or for self-assembling them into nanocolumns (NCls), all oriented perpendicular to the substrate. In order to change the kinetic energy of the species arriving at the substrate, we use a background gas during the deposition of the embedding a-Al(2)O(3) host. It was produced either in vacuum or in a gas pressure (helium and argon) while the metal NPs were always produced in vacuum. The formation of NPs or NCls is easily identified through the features of the surface plasmon resonances (SPR) in the extinction spectra and confirmed by electron microscopy. The results show that both the layer organization and self-assembling of the metal are prevented when the host is produced in a gas pressure. This result is discussed in terms of the deceleration of species arriving at the substrate in gas that reduces the metal sputtering by host species (by ≈58%) as well as the density of the host material (by ≥19%). These reductions promote the formation of large voids along which the metal easily diffuses, thus preventing organization and self-organisation, as well as an enhancement of the amount of metal that is deposited.

Malaria heat shock proteins: drug targets that chaperone other drug targets.

Ongoing research into the chaperone systems of malaria parasites, and particularly of Plasmodium falciparum, suggests that heat shock proteins (Hsps) could potentially be an excellent class of drug targets. The P. falciparum genome encodes a vast range and large number of chaperones, including 43 Hsp40, six Hsp70, and three Hsp90 proteins (PfHsp40s, PfHsp70s and PfHsp90s), which are involved in a number of fundamental cellular processes including protein folding and assembly, protein translocation, signal transduction and the cellular stress response. Despite the fact that Hsps are relatively conserved across different species, PfHsps do exhibit a considerable number of unique structural and functional features. One PfHsp90 is thought to be sufficiently different to human Hsp90 to allow for selective targeting. PfHsp70s could potentially be used as drug targets in two ways: either by the specific inhibition of Hsp70s by small molecule modulators, as well as disruption of the interactions between Hsp70s and co-chaperones such as the Hsp70/Hsp90 organising protein (Hop) and Hsp40s. Of the many PfHsp40s present on the parasite, there are certain unique or essential members which are considered to have good potential as drug targets. This review critically evaluates the potential of Hsps as malaria drug targets, as well as the use of chaperones as aids in the heterologous expression of other potential malarial drug targets.

Screening ventilation strategies for confined-space manure storage facilities.

Fatalities associated with entry into on-farm confined-space manure storage facilities occur each year. The fatalities are due to asphyxiation or poisoning by exposure to high concentrations of hydrogen sulfide, methane, and carbon dioxide. Forced ventilation has been shown to be an effective way to reduce concentrations of noxious gases to levels that are safe for human entry into these storage facilities. Hydrogen sulfide (H2S) was used as an indicator gas to investigate the effectiveness of forced-air ventilation strategies for eliminating the toxic and oxygen-deficient atmosphere in confined-space manure storage facilities. This article focuses on experimental methods for identifying ventilation strategies that effectively reduce toxic gas (i.e., H2S) concentrations in a fan-ventilated confined-space manure tank to the OSHA permissible exposure limit (PEL) (H2S PEL = 10 ppm) and to 25% of the initial gas concentration. Typical H2S concentration reduction curves during forced-air ventilation were identified in the tank as well. Based on the experimental tests conducted in this research, the most promising candidate ventilation strategies were identified for this rectangular confined-space manure tank with solid, fully slotted, and partially slotted covers. In addition, based on the results of experimental tests, a field-based database was developed for future validation of computational fluid dynamics modeling protocols.

The Hsp40 proteins of Plasmodium falciparum and other apicomplexa: regulating chaperone power in the parasite and the host.

Extensive structural and functional remodelling of Plasmodium falciparum (malaria)-infected erythrocytes follows the export of a range of proteins of parasite origin (exportome) across the parasitophorous vacuole into the host erythrocyte. The genome of P. falciparum encodes a diverse chaperone complement including at least 43 members of the heat shock protein 40kDa (Hsp40) family, and six members of the heat shock protein 70kDa (Hsp70) family. Nearly half of the Hsp40 proteins of P. falciparum are predicted to contain a PEXEL/HT (Plasmodium export element/host targeting signal) sequence motif, and hence are likely to be part of the exportome. In this review we critically evaluate the classification, sequence similarity and clustering, and possible interactors of the P. falciparum Hsp40 chaperone machinery. In addition to the types I, II and III Hsp40 proteins all exhibiting the signature J-domain, the P. falciparum genome also encodes a number of specialized Hsp40 proteins with a J-like domain, which we have categorized as type IV Hsp40 proteins. Analysis of the potential P. falciparum Hsp40 protein interaction network revealed connections predominantly with cytoskeletal and membrane proteins, transcriptional machinery, DNA repair and replication machinery, translational machinery, the proteasome and proteolytic enzymes, and enzymes involved in cellular physiology. Comparison of the Hsp40 proteins of P. falciparum to those of other apicomplexa reveals that most of the proteins (especially the PEXEL/HT-containing proteins) are unique to P. falciparum. Furthermore, very few of the P. falciparum Hsp40 proteins have human homologs, except for those proteins implicated in fundamental biological processes. Our analysis suggests that P. falciparum has evolved an expanded and specialized Hsp40 protein machinery to enable it successfully to invade and remodel the human erythrocyte, and we propose a model in which these proteins are involved in chaperone-mediated translocation, folding, assembly and regulation of parasite and host proteins.

Cytosolic and ER J-domains of mammalian and parasitic origin can functionally interact with DnaK.

Both prokaryotic and eukaryotic cells contain multiple heat shock protein 40 (Hsp40) and heat shock protein 70 (Hsp70) proteins, which cooperate as molecular chaperones to ensure fidelity at all stages of protein biogenesis. The Hsp40 signature domain, the J-domain, is required for binding of an Hsp40 to a partner Hsp70, and may also play a role in the specificity of the association. Through the creation of chimeric Hsp40 proteins by the replacement of the J-domain of a prokaryotic Hsp40 (DnaJ), we have tested the functional equivalence of J-domains from a number of divergent Hsp40s of mammalian and parasitic origin (malarial Pfj1 and Pfj4, trypanosomal Tcj3, human ERj3, ERj5, and Hsj1, and murine ERj1). An in vivo functional assay was used to test the functionality of the chimeric proteins on the basis of their ability to reverse the thermosensitivity of a dnaJ cbpA mutant Escherichia coli strain (OD259). The Hsp40 chimeras containing J-domains originating from soluble (cytosolic or endoplasmic reticulum (ER)-lumenal) Hsp40s were able to reverse the thermosensitivity of E. coli OD259. In all cases, modified derivatives of these chimeric proteins containing an His to Gln substitution in the HPD motif of the J-domain were unable to reverse the thermosensitivity of E. coli OD259. This suggested that these J-domains exerted their in vivo functionality through a specific interaction with E. coli Hsp70, DnaK. Interestingly, a Hsp40 chimera containing the J-domain of ERj1, an integral membrane-bound ER Hsp40, was unable to reverse the thermosensitivity of E. coli OD259, suggesting that this J-domain was unable to functionally interact with DnaK. Substitutions of conserved amino acid residues and motifs were made in all four helices (I-IV) and the loop regions of the J-domains, and the modified chimeric Hsp40s were tested for functionality using the in vivo assay. Substitution of a highly conserved basic residue in helix II of the J-domain was found to disrupt in vivo functionality for all the J-domains tested. We propose that helix II and the HPD motif of the J-domain represent the fundamental elements of a binding surface required for the interaction of Hsp40s with Hsp70s, and that this surface has been conserved in mammalian, parasitic and bacterial systems.

Antirheumatic effect of pirfenidone in a double blind clinical pilot trial in humans.

The antirheumatic effect of pirfenidone was compared with a positive control drug, oxyphenbutazone which is used in patients suffering from rheumatoid arthritis, in a double blind clinical trial in humans. The data collected in this pilot project revealed that pirfenidone was more effective (p < 0.025) than oxyphenbutazone in providing relief from arthritic pain. In addition, a greater number (p < 0.025) of patients reported favorable response to oral pirfenidone than oral oxyphenbutazone. However, there were no significant differences in the number of patients who dropped out from the trial and the number of patients who tolerated the drugs for 21 days of the trial between the pirfenidone and oxyphenbutazone groups. It was concluded from this pilot study that pirfenidone potentially offers a novel therapeutic modality for the management of rheumatoid arthritis with little or no adverse effects unlike steroidal and non-steroidal anti-inflammatory drugs which are frequently used for this chronic debilitating disease.

SAR studies in the field of calcium(II) antagonists. Effect of modifications at the tetrasubstituted carbon of verapamil-like compounds.

A number of fluorenyl and diphenylmethane analogues of verapamil, chosen as having the same substituents arranged in different ways around the quaternary carbon, were synthesized in order to evaluate the importance of the stereoisomerism at that point of the molecule. The compounds were tested with the Langendorff technique and coronary perfusion pressure (CPP), left ventricular pressure (LVP), and heart rate (HR) were recorded. While most of the compounds were almost inactive on these parameters, three of them did show interesting cardiovascular action. In particular they produced a more pronounced decrease in CPP than verapamil, with a less marked negative inotropic effect. Structure-activity relationships and the mechanism of action of the compounds are discussed.

[Metabolism of vincamine in the rat]. / Metabolismo della vincamina nel ratto.

The metabolism of vincamine hydrochloride was studied in the rat after oral administration of the drug. Vincamine is almost completely metabolized, only a small fraction of the original compound being excreted in the urine. The metabolites detected in blood, urine and tissues were purified by preparative thin layer and column chromatography in several solvent systems, and analyzed by mass spectrometry. It was found that the main urinary metabolites were vincamine conjugates (sulphates and glucuronides). Two new metabolites were detected in all the biological fluids and specimens analyzed: these compounds are more polar than vincamine and their structure was characterized by mass spectrometry, I.R. and U.V. spectroscopy and confirmed by synthesis in our laboratory.