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Sample records for agents including platinum

  1. Cataloging antineoplastic agents according to their effectiveness against platinum-resistant and platinum-sensitive ovarian carcinoma cell lines

    PubMed Central

    Ishiguro, Kimiko; Zhu, Yong-Lian; Lin, Z. Ping; Penketh, Philip G.; Shyam, Krishnamurthy; Zhu, Rui; Baumann, Raymond P.; Sartorelli, Alan C.; Rutherford, Thomas J.; Ratner, Elena S.

    2016-01-01

    Although epithelial ovarian cancers (EOCs) are initially treated with platinum-based chemotherapy, EOCs vary in platinum responsiveness. Cataloging antineoplastic agents according to their effectiveness against platinum-resistant and platinum-sensitive EOC cell lines is valuable for development of therapeutic strategies to avoid platinum inefficacy and to exploit platinum sensitivity. TOV-21G devoid of FANCF expression, OV-90 and SKOV-3 were employed as examples of platinum-sensitive, platinum-intermediate and platinum-resistant cell lines, respectively. Antineoplastic agents examined included mitomycin C, doxorubicin, etoposide, gemcitabine, chlorambucil, paclitaxel, triapine and X-rays. Their effectiveness against cell lines was analyzed by clonogenic assays. Cytotoxic profiles of mitomycin C and carboplatin were similar, with mitomycin C exhibiting greater potency and selectivity against TOV-21G than carboplatin. Cytotoxic profiles of doxorubicin, etoposide and X-rays overlapped with that of carboplatin, while OV-90 overexpressing Rad51 was more resistant to chlorambucil than SKOV-3. The efficacy of paclitaxel and triapine was independent of platinum sensitivity or resistance. Consistent with these cytotoxic profiles, cisplatin/mitomycin C, triapine, and paclitaxel differed in the capacity to induce phosphorylation of H2AX, and produced unique inhibitory patterns of DNA/RNA syntheses in HL-60 human leukemia cells. Paclitaxel and triapine in combination produced additive antitumor effects in M109 murine lung carcinoma. In conclusion, mitomycin C is potentially more effective against Fanconi anemia pathway-deficient EOCs than carboplatin. Doxorubicin and etoposide, because of their overlapping cytotoxic properties with carboplatin, are unlikely to be efficacious against platinum-refractory EOCs. Paclitaxel and triapine are effective regardless of platinum sensitivity status, and promising in combination for both platinum-sensitive and platinum-refractory EOCs

  2. [Clinical pharmacology of anticancer agents. (Part 1) Introduction, alkylating agents and platinum compounds].

    PubMed

    Fujita, H

    1991-11-01

    Pharmacokinetic concepts as to absorption, distribution, metabolism and excretion of anticancer agents, and how drugs reach to the site of action were reviewed. Then, roles of the liver and kidney to the excretion and metabolism, intracellular pharmacokinetics, and relationships between drug response and cell proliferation kinetics or cell cycle phase were explained. Drug development, mode of action and pharmacokinetics of alkylating agents and platinum compounds were reviewed. This includes: alkylating agents: nitrogen mustard, phenylalanine mustard, estracyte, cyclophosphamide, carboquone, busulfan, nitrosourea, etc., and platinum compounds: cisplatin, carboplatin, 254-S, DWA-2114 R, NK-121. PMID:1952967

  3. Monofunctional and Higher-Valent Platinum Anticancer Agents

    PubMed Central

    Johnstone, Timothy C.; Wilson, Justin J.

    2013-01-01

    Platinum compounds represent one of the great success stories of metals in medicine. Following the serendipitous discovery of the anticancer activity of cisplatin by Rosenberg, a large number of cisplatin variants have been prepared and tested for their ability to kill cancer cells and inhibit tumor growth. These efforts continue today with increased realization that new strategies are needed to overcome issues of toxicity and resistance inherent to treatment by the approved platinum anticancer agents. One approach has been the use of so-called “non-traditional” platinum(II) and platinum(IV) compounds that violate the structure-activity relationships that governed platinum drug-development research for many years. Another is the use of specialized drug delivery strategies. Here we describe recent developments from our laboratory involving monofunctional platinum(II) complexes together with an historical account of the manner by which we came to investigate these compounds and their relationship to previously studied molecules. We also discuss work carried out using platinum(IV) prodrugs and the development of nanoconstructs designed to deliver them in vivo. PMID:23738524

  4. The Next Generation of Platinum Drugs: Targeted Pt(II) Agents, Nanoparticle Delivery, and Pt(IV) Prodrugs

    PubMed Central

    Johnstone, Timothy C.; Suntharalingam, Kogularamanan; Lippard, Stephen J.

    2016-01-01

    The platinum drugs, cisplatin, carboplatin, and oxaliplatin, prevail in the treatment of cancer,, but new platinum agents have been very slow to enter the clinic. Recently, however, there has been a surge of activity, based on a great deal of mechanistic information, aimed at developing non-classical platinum complexes that operate via mechanisms of action distinct from those of the approved drugs. The use of nanodelivery devices has also grown and many different strategies have been explored to incorporate platinum warheads into nanomedicine constructs. In this review, we discuss these efforts to create the next generation of platinum anticancer drugs. The introduction provides the reader with a brief overview of the use, development, and mechanism of action of the approved platinum drugs to provide the context in which more recent research has flourished. We then describe approaches that explore non-classical platinum(II) complexes with trans geometry and with a monofunctional coordination mode, polynuclear platinum(II) compounds, platinum(IV) prodrugs, dual-treat agents, and photoactivatable platinum(IV) complexes. Nanodelivery particles designed to deliver platinum(IV) complexes will also be discussed, including carbon nanotubes, carbon nanoparticles, gold nanoparticles, quantum dots, upconversion nanoparticles, and polymeric micelles. Additional nanoformulations including supramolecular self-assembled structures, proteins, peptides, metal-organic frameworks, and coordination polymers will then be described. Finally, the significant clinical progress made by nanoparticle formulations of platinum(II) agents will be reviewed. We anticipate that such a synthesis of disparate research efforts will not only help to generate new drug development ideas and strategies, but also reflect our optimism that the next generation of platinum cancer drugs is about to arrive. PMID:26865551

  5. The Next Generation of Platinum Drugs: Targeted Pt(II) Agents, Nanoparticle Delivery, and Pt(IV) Prodrugs.

    PubMed

    Johnstone, Timothy C; Suntharalingam, Kogularamanan; Lippard, Stephen J

    2016-03-01

    The platinum drugs, cisplatin, carboplatin, and oxaliplatin, prevail in the treatment of cancer, but new platinum agents have been very slow to enter the clinic. Recently, however, there has been a surge of activity, based on a great deal of mechanistic information, aimed at developing nonclassical platinum complexes that operate via mechanisms of action distinct from those of the approved drugs. The use of nanodelivery devices has also grown, and many different strategies have been explored to incorporate platinum warheads into nanomedicine constructs. In this Review, we discuss these efforts to create the next generation of platinum anticancer drugs. The introduction provides the reader with a brief overview of the use, development, and mechanism of action of the approved platinum drugs to provide the context in which more recent research has flourished. We then describe approaches that explore nonclassical platinum(II) complexes with trans geometry or with a monofunctional coordination mode, polynuclear platinum(II) compounds, platinum(IV) prodrugs, dual-threat agents, and photoactivatable platinum(IV) complexes. Nanoparticles designed to deliver platinum(IV) complexes will also be discussed, including carbon nanotubes, carbon nanoparticles, gold nanoparticles, quantum dots, upconversion nanoparticles, and polymeric micelles. Additional nanoformulations, including supramolecular self-assembled structures, proteins, peptides, metal-organic frameworks, and coordination polymers, will then be described. Finally, the significant clinical progress made by nanoparticle formulations of platinum(II) agents will be reviewed. We anticipate that such a synthesis of disparate research efforts will not only help to generate new drug development ideas and strategies, but also will reflect our optimism that the next generation of approved platinum cancer drugs is about to arrive. PMID:26865551

  6. Water-soluble platinum phthalocyanines as potential antitumor agents.

    PubMed

    Bologna, Giuseppina; Lanuti, Paola; D'Ambrosio, Primiano; Tonucci, Lucia; Pierdomenico, Laura; D'Emilio, Carlo; Celli, Nicola; Marchisio, Marco; d'Alessandro, Nicola; Santavenere, Eugenio; Bressan, Mario; Miscia, Sebastiano

    2014-06-01

    Breast cancer represents the second cause of death in the European female population. The lack of specific therapies together with its high invasive potential are the major problems associated to such a tumor. In the last three decades platinum-based drugs have been considered essential constituents of many therapeutic strategies, even though with side effects and frequent generation of drug resistance. These drugs have been the guide for the research, in last years, of novel platinum and ruthenium based compounds, able to overcome these limitations. In this work, ruthenium and platinum based phthalocyanines were synthesized through conventional techniques and their antiproliferative and/or cytotoxic actions were tested. Normal mammary gland (MCF10A) and several models of mammarian carcinoma at different degrees of invasiveness (BT474, MCF-7 and MDA-MB-231) were used. Cells were treated with different concentrations (5-100 μM) of the above reported compounds, to evaluate toxic concentration and to underline possible dose-response effects. The study included growth curves made by trypan blue exclusion test and scratch assay to study cellular motility and its possible negative modulation by phthalocyanine. Moreover, we investigated cell cycle and apoptosis through flow cytometry and AMNIS Image Stream cytometer. Among all the tested drugs, tetrasulfonated phthalocyanine of platinum resulted to be the molecule with the best cytostatic action on neoplastic cell lines at the concentration of 30 μM. Interestingly, platinum tetrasulfophtalocyanine, at low doses, had no antiproliferative effects on normal cells. Therefore, such platinum complex, appears to be a promising drug for mammarian carcinoma treatment. PMID:24699848

  7. Efficacy of platinum chemotherapy agents in the adjuvant setting for adenosquamous carcinoma of the pancreas

    PubMed Central

    Wild, Aaron T.; Dholakia, Avani S.; Fan, Katherine Y.; Kumar, Rachit; Moningi, Shalini; Rosati, Lauren M.; Laheru, Daniel A.; Zheng, Lei; De Jesus-Acosta, Ana; Ellsworth, Susannah G.; Hacker-Prietz, Amy; Voong, Khinh R.; Tran, Phuoc T.; Hruban, Ralph H.; Pawlik, Timothy M.; Wolfgang, Christopher L.

    2015-01-01

    Background Pancreatic adenosquamous carcinoma (PASC) accounts for only 1-4% of all exocrine pancreatic cancers and carries a particularly poor prognosis. This retrospective study was performed to determine whether inclusion of a platinum agent as part of adjuvant therapy is associated with improved survival in patients with resected PASC. Methods Records of all patients who underwent pancreatic resection at Johns Hopkins Hospital from 1986 to 2012 were reviewed to identify those with PASC. Multivariable Cox proportional hazards modeling was used to assess for significant associations between patient characteristics and survival. Results In total, 62 patients (1.1%) with resected PASC were identified among 5,627 cases. Median age was 68 [interquartile range (IQR), 57-77] and 44% were female. Multivariate analysis revealed that, among all patients (n=62), the following factors were independently predictive of poor survival: lack of adjuvant therapy [hazard ratio (HR) =3.6; 95% confidence interval (CI), 1.8-7.0; P<0.001], margin-positive resection (HR =3.5; 95% CI, 1.8-6.8; P<0.001), lymph node involvement (HR =3.5; 95% CI, 1.5-8.2; P=0.004), and age (HR =1.0; 95% CI, 1.0-1.1; P=0.035). There were no significant differences between patients who did and did not receive adjuvant therapy following resection (all P>0.05). A second multivariable model included only those patients who received adjuvant therapy (n=39). Lack of inclusion of a platinum agent in the adjuvant regimen (HR =2.4; 95% CI, 1.0-5.8; P=0.040) and larger tumor diameter (HR =1.3; 95% CI, 1.0-1.6; P=0.047) were independent predictors of inferior survival. Conclusions Addition of a platinum agent to adjuvant regimens for resected PASC may improve survival among these high-risk patients, though collaborative prospective investigation is needed. PMID:25830031

  8. Advances in drug delivery system for platinum agents based combination therapy

    PubMed Central

    Kang, Xiang; Xiao, Hai-Hua; Song, Hai-Qin; Jing, Xia-Bin; Yan, Le-San; Qi, Ruo-Gu

    2015-01-01

    Platinum-based anticancer agents are widely used as first-line drugs in cancer chemotherapy for various solid tumors. However, great side effects and occurrence of resistance remain as the major drawbacks for almost all the platinum drugs developed. To conquer these problems, new strategies should be adopted for platinum drug based chemotherapy. Modern nanotechnology has been widely employed in the delivery of various therapeutics and diagnostic. It provides the possibility of targeted delivery of a certain anticancer drug to the tumor site, which could minimize toxicity and optimize the drug efficacy. Here, in this review, we focused on the recent progress in polymer based drug delivery systems for platinum-based combination therapy. PMID:26779373

  9. Linker design for the modular assembly of multifunctional and targeted platinum(ii)-containing anticancer agents.

    PubMed

    Ding, S; Bierbach, U

    2016-08-16

    A versatile and efficient modular synthetic platform was developed for assembling multifunctional conjugates and targeted forms of platinum-(benz)acridines, a class of highly cytotoxic DNA-targeted hybrid agents. The synthetic strategy involved amide coupling between succinyl ester-modified platinum compounds (P1, P2) and a set of 11 biologically relevant primary and secondary amines (N1-N11). To demonstrate the feasibility and versatility of the approach, a structurally and functionally diverse range of amines was introduced. These include biologically active molecules, such as rucaparib (a PARP inhibitor), E/Z-endoxifen (an estrogen receptor antagonist), and a quinazoline-based tyrosine kinase inhibitor. Micro-scale reactions in Eppendorf tubes or on 96-well plates were used to screen for optimal coupling conditions in DMF solution with carbodiimide-, uronium-, and phosphonium-based compounds, as well as other common coupling reagents. Reactions with the phosphonium-based coupling reagent PyBOP produced the highest yields and gave the cleanest conversions. Furthermore, it was demonstrated that the chemistry can also be performed in aqueous media and is amenable to parallel synthesis based on multiple consecutive reactions in DMF in a "one-tube" format. In-line LC-MS was used to assess the stability of the conjugates in physiologically relevant buffers. Hydrolysis of the conjugates occurs at the ester moiety and is facilitated by the aquated metal moiety under low-chloride ion conditions. The rate of ester cleavage greatly depends on the nature of the amine component. Potential applications of the linker technology are discussed. PMID:27251881

  10. 13 CFR 107.1620 - Functions of agents, including Central Registration Agent, Selling Agent and Fiscal Agent.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Functions of agents, including Central Registration Agent, Selling Agent and Fiscal Agent. 107.1620 Section 107.1620 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION SMALL BUSINESS INVESTMENT COMPANIES SBA Financial Assistance...

  11. 13 CFR 108.1620 - Functions of agents, including Central Registration Agent, Selling Agent and Fiscal Agent.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Functions of agents, including Central Registration Agent, Selling Agent and Fiscal Agent. 108.1620 Section 108.1620 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION NEW MARKETS VENTURE CAPITAL (âNMVCâ) PROGRAM SBA...

  12. Combination of Genistein and Cisplatin with Two Designed Monofunctional Platinum Agents in Human Ovarian Tumour Models.

    PubMed

    Arzuman, Laila; Beale, Philip; Proschogo, Nick; Yu, Jun Q; Huq, Fazlul

    2015-11-01

    A great amount of research effort has been directed at platinum compounds that bind with DNA differently from cisplatin with the idea that the difference may translate into an altered spectrum of activity. Recently research has also been directed at applying combinations of platinum agents with tumour-active phytochemicals with the aim of providing a means of overcoming platinum resistance in ovarian cancer. Herein we report the synthesis of monofunctional platinum tris(3-hydroxypyridine)chloroplatinum(II) chloride (coded as LH1) and tris(imidazole)chloroplatinum(II) chloride (coded as LH2), and their activity alone and in combination with genistein and cisplatin against human ovarian A2780, cisplatin-resistant A2780(cisR) and picoplatin-resistant A2780(ZD0473R) cancer cell lines. Although both LH1 and LH2 were found to be less active than cisplatin against the tumour models, they produced synergistic outcomes in combination with genistein. Both the level of cellular accumulation of Pt and of Pt-DNA binding resulting from the combination were greater in the A2780(cisR) cell line than in the parental A2780 cell line, irrespective of the sequence of administration. Absence of association between activity of LH1 and LH2 and the level of Pt-DNA binding indicates that the cell death induced by LH1 and LH2 may not be limited to the effect of their binding with DNA. PMID:26504026

  13. Nucleotide Binding Preference of the Monofunctional Platinum Anticancer-Agent Phenanthriplatin.

    PubMed

    Riddell, Imogen A; Johnstone, Timothy C; Park, Ga Young; Lippard, Stephen J

    2016-05-23

    The monofunctional platinum anticancer agent phenanthriplatin generates covalent adducts with the purine bases guanine and adenine. Preferential nucleotide binding was investigated by using a polymerase stop assay and linear DNA amplification with a 163-base pair DNA double helix. Similarly to cisplatin, phenanthriplatin forms the majority of adducts at guanosine residues, but significant differences in both the number and position of platination sites emerge when comparing results for the two complexes. Notably, the monofunctional complex generates a greater number of polymerase-halting lesions at adenosine residues than does cisplatin. Studies with 9-methyladenine reveal that, under abiological conditions, phenanthriplatin binds to the N(1) or N(7) position of 9-methyladenine in approximately equimolar amounts. By contrast, comparable reactions with 9-methylguanine afforded only the N(7) -bound species. Both of the 9-methyladenine linkage isomers (N(1) and N(7) ) exist as two diastereomeric species, arising from hindered rotation of the aromatic ligands about their respective platinum-nitrogen bonds. Eyring analysis of rate constants extracted from variable-temperature NMR spectroscopic data revealed that the activation energies for ligand rotation in the N(1) -bound platinum complex and the N(7) -linkage isomers are comparable. Finally, a kinetic analysis indicated that phenanthriplatin reacts more rapidly, by a factor of eight, with 9-methylguanine than with 9-methyladenine, suggesting that the distribution of lesions formed on double-stranded DNA is kinetically controlled. In addition, implications for the potent anticancer activity of phenanthriplatin are discussed herein. PMID:27111128

  14. Design of enzymatically cleavable prodrugs of a potent platinum-containing anticancer agent.

    PubMed

    Ding, Song; Pickard, Amanda J; Kucera, Gregory L; Bierbach, Ulrich

    2014-12-01

    Using a versatile synthetic approach, a new class of potential ester prodrugs of highly potent, but systemically too toxic, platinum-acridine anticancer agents was generated. The new hybrids contain a hydroxyl group, which has been masked with a cleavable lipophilic acyl moiety. Both butanoic (butyric) and bulkier 2-propanepentanoic (valproic) esters were introduced. The goals of this design were to improve the drug-like properties (e.g., logD) and to reduce the systemic toxicity of the pharmacophore. Two distinct pathways by which the target compounds undergo effective ester hydrolysis, the proposed activating step, have been confirmed: platinum-assisted, self-immolative ester cleavage in a low-chloride environment (LC-ESMS, NMR spectroscopy) and enzymatic cleavage by human carboxylesterase-2 (hCES-2) (LC-ESMS). The valproic acid ester derivatives are the first example of a metal-containing agent cleavable by the prodrug-converting enzyme. They show excellent chemical stability and reduced systemic toxicity. Preliminary results from screening in lung adenocarcinoma cell lines (A549, NCI-H1435) suggest that the mechanism of the valproic esters may involve intracellular deesterification. PMID:25303639

  15. Phase Ib-IIa study to reverse platinum resistance by the use of a hypomethylating agent azacitidine in platinum-resistant or refractory epithelial ovarian cancer

    PubMed Central

    Fu, Siqing; Hu, Wei; Iyer, Revathy; Kavanagh, John J.; Coleman, Robert L.; Levenback, Charles F.; Sood, Anil K.; Wolf, Judith K.; Gershenson, David M.; Markman, Maurie; Hennessy, Bryan T.; Kurzrock, Razelle; Bast, Robert C.

    2010-01-01

    Background Sequential treatment with azacitidine can induce re-expression of epigenetically silenced genes through genomic DNA hypomethylation and reverse carboplatin resistance of epithelial ovarian cancer cells. We initiated a phase Ib-IIa clinical trial of this sequential combination of azacitidine and carboplatin in platinum-resistant or refractory epithelial ovarian cancer. Methods Patients with pathologically confirmed intermediate- or high-grade epithelial ovarian cancer who had disease progression within 6 months (resistant, n = 18) or during a platinum-based therapy (refractory, n = 12) were eligible. All patients had measurable disease. Results Thirty patients received a total of 163 cycles of treatment. This regimen produced 1 CR, 3 PR (ORR: 13.8%), and 10 SD among 29 evaluable patients. For those who achieved clinical benefits, the median duration of the treatment was 7.5 months. The median PFS and OS for all patients were 3.7 months and 14 months, respectively. Patients with platinum resistant disease achieved an ORR of 22%, with a median PFS of 5.6 months and a median OS of 23 months. The predominant toxicities were fatigue and myelosuppression. Correlative studies showed that DR4 methylation in peripheral blood leukocytes was decreased during treatment in 3 of 4 objective responders (75%), but in only 5 of 13 non-responders (38%). Conclusions To our knowledge, this study provides the first clinical evidence that a hypomethylating agent may partially reverse platinum resistance in ovarian cancer. Further clinical evaluation of hypomethylating agents in combination with carboplatin is warranted. PMID:21472713

  16. Effects of monofunctional platinum agents on bacterial growth: a retrospective study.

    PubMed

    Johnstone, Timothy C; Alexander, Sarah M; Lin, Wei; Lippard, Stephen J

    2014-01-01

    The effect of the novel and potent monofunctional platinum(II) agent phenanthriplatin on Escherichia coli and bacteriophage λ lysogens is reported. E. coli filamentation was observed by light microscopy when cells were grown in the presence of phenanthriplatin, cis-[Pt(NH3)2(Am)Cl](+) where Am is phenanthridine. Treatment of lysogenic bacteria with this compound resulted in lysis and the production of viral particles, as indicated by plaque formation in a bacterial lawn. The results obtained with phenanthriplatin are contextualized by comparison with those obtained using cisplatin as well as other, less active, monofunctional compounds such as [Pt(NH3)3Cl](+) and cis-[Pt(NH3)2(py)Cl](+), where py is pyridine. The ability of phenanthriplatin to induce bacterial filamentation and initiate lysis in lysogenic bacteria corroborates the hypothesis that the biological activity of this complex is mediated by its interaction with DNA. PMID:24364388

  17. Design of Enzymatically Cleavable Prodrugs of a Potent Platinum-Containing Anticancer Agent

    PubMed Central

    Ding, Song; Pickard, Amanda J.; Kucera, Gregory L.

    2014-01-01

    Using a versatile synthetic approach, a new class of potential ester prodrugs of highly potent, but systemically too toxic, platinum–acridine anticancer agents was generated. The new hybrids contain a hydroxyl group, which has been masked with a cleavable lipophilic acyl moiety. Both butanoic (butyric) and bulkier 2-propanepentanoic (valproic) esters were introduced. The goals of this design were to improve the drug-like properties (e.g., logD) and to reduce the systemic toxicity of the pharmacophore. Two distinct pathways by which the target compounds undergo effective ester hydrolysis, the proposed activating step, have been confirmed: platinum-assisted, self-immolative ester cleavage in a low-chloride environment (LC-ESMS, NMR spectroscopy) and enzymatic cleavage by human carboxylesterase-2 (hCES-2) (LC-ESMS). The valproic acid ester derivatives are the first example of a metal-containing agent cleavable by the pro-drug-converting enzyme. They show excellent chemical stability and reduced systemic toxicity. Preliminary results from screening in lung adenocarcinoma cell lines (A549, NCI-H1435) suggest that the mechanism of the valproic esters may involve intracellular deesterification. PMID:25303639

  18. Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents

    PubMed Central

    Apps, Michael G.; Johnson, Ben W.; Sutcliffe, Oliver B.; Brown, Sarah D.; Wheate, Nial J.

    2014-01-01

    Amide coupling reactions can be used to synthesize bispyridine-based ligands for use as bridging linkers in multinuclear platinum anticancer drugs. Isonicotinic acid, or its derivatives, are coupled to variable length diaminoalkane chains under an inert atmosphere in anhydrous DMF or DMSO with the use of a weak base, triethylamine, and a coupling agent, 1-propylphosphonic anhydride. The products precipitate from solution upon formation or can be precipitated by the addition of water. If desired, the ligands can be further purified by recrystallization from hot water. Dinuclear platinum complex synthesis using the bispyridine ligands is done in hot water using transplatin. The most informative of the chemical characterization techniques to determine the structure and gross purity of both the bispyridine ligands and the final platinum complexes is 1H NMR with particular analysis of the aromatic region of the spectra (7-9 ppm). The platinum complexes have potential application as anticancer agents and the synthesis method can be modified to produce trinuclear and other multinuclear complexes with different hydrogen bonding functionality in the bridging ligand. PMID:24893964

  19. Binuclear platinum (II)-terpyridine complexes. A new class of bifunctional DNA-intercalating agent.

    PubMed Central

    McFadyen, W D; Wakelin, L P; Roos, I A; Hillcoat, B L

    1986-01-01

    A series of binuclear DNA-binding ligands was prepared by linking two (2,2':6',2"-terpyridine)platinum(II) moieties via alpha omega-dithiols of the type HS-[CH2]n-SH where n = 4-10. A monomeric analogue was also synthesized. Compounds were characterized by elemental analysis and electronic and n.m.r. spectroscopy. Viscometric measurements with sonicated rod-like DNA fragments and covalently closed circular DNA were performed to investigate the mode of binding of these agents. The ligands with n = 5 and 6 function as bis intercalators and form a single 'base-pair sandwich' in violation of neighbour-exclusion binding. Bifunctional reaction occurs for the ligand with n = 7, whereas the ligands with n = 8 and 10 show a preference for mixed monofunctional/bifunctional binding. The data do not permit definitive assignment of the binding mode of the ligands with n = 4 and 9. All compounds are growth-inhibitory against mouse leukaemia L1210 cells in culture with IC50 values in the range 2-14 microM. PMID:3800959

  20. The new platinum-based anticancer agent LA-12 induces retinol binding protein 4 in vivo

    PubMed Central

    2011-01-01

    Background The initial pharmacokinetic study of a new anticancer agent (OC-6-43)-bis(acetato)(1-adamantylamine)amminedichloroplatinum (IV) (LA-12) was complemented by proteomic screening of rat plasma. The objective of the study was to identify new LA-12 target proteins that serve as markers of LA-12 treatment, response and therapy monitoring. Methods Proteomic profiles were measured by surface-enhanced laser desorption-ionization time-of-flight mass spectrometry (SELDI-TOF MS) in 72 samples of rat plasma randomized according to LA-12 dose and time from administration. Correlation of 92 peak clusters with platinum concentration was evaluated using Spearman correlation analysis. Results We identified Retinol-binding protein 4 (RBP4) whose level correlated with LA-12 level in treated rats. Similar results were observed in randomly selected patients involved in Phase I clinical trials. Conclusions RBP4 induction is in agreement with known RBP4 regulation by amantadine and cisplatin. Since retinol metabolism is disrupted in many cancers and inversely associates with malignancy, these data identify a potential novel mechanism for the action of LA-12 and other similar anti-cancer drugs. PMID:22040120

  1. Agents in Safety Related Systems Including Ubiquitous Networks

    NASA Astrophysics Data System (ADS)

    Strandén, Lars

    The ADM (Autonomous Decision Maker) concept concerns the possibility of including intelligent interfaces, agent like, for supporting the use of ubiquitous networks, such as the Internet, in safety related applications. The need for such interfaces is inevitable if remote surveillance and control shall be supported. The single most important aspect of ADM is its capability of handling limited resources when making intelligent decisions. Intelligence in ADM is manifested in reasoning and learning. This paper outlines the role of ADM and especially in relation to the standard IEC 61508 and presents the overall properties that result. These are exemplified by a presentation of ADM demonstrator.

  2. Multi-platinum anti-cancer agents. Substitution-inert compounds for tumor selectivity and new targets.

    PubMed

    Farrell, N P

    2015-12-21

    This tutorial review summarizes chemical, biophysical and cellular biological properties of formally substitution-inert "non-covalent" polynuclear platinum complexes (PPCs). We demonstrate how modulation of the pharmacological factors affecting platinum compound cytotoxicity such as cellular accumulation, reactivity toward extracellular and intracellular sulfur-ligand nucleophiles and consequences of DNA binding is achieved to afford a profile of biological activity distinct from that of covalently-binding agents. The DNA binding of substitution-inert complexes is achieved by molecular recognition through minor groove spanning and backbone tracking of the phosphate clamp. In this situation, the square-planar tetra-am(m)ine Pt(ii) coordination units hydrogen bond to phosphate oxygen OP atoms to form bidentate N-O-N motifs. The modular nature of the polynuclear compounds results in high-affinity binding to DNA and very efficient nuclear condensation. These combined effects distinguish the phosphate clamp as a third mode of ligand-DNA binding, discrete from intercalation and minor-groove binding. The cellular consequences mirror those of the biophysical studies and a significant portion of nuclear DNA is compacted, a unique effect different from mitosis, senescence or apoptosis. Substitution-inert PPCs display cytotoxicity similar to cisplatin in a wide range of cell lines, and sensitivity is indifferent to p53 status. Cellular accumulation is mediated through binding to heparan sulfate proteoglycans (HSPG) allowing for possibilities of tumor selectivity as well as disruption of HSPG function, opening new targets for platinum antitumor agents. The combined properties show that covalently-binding chemotypes are not the unique arbiters of cytotoxicity and antitumor activity and meaningful antitumor profiles can be achieved even in the absence of Pt-DNA bond formation. These dual properties make the substitution-inert compounds a unique class of inherently dual

  3. 78 FR 60270 - Platinum Energy, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Platinum Energy, LLC; Supplemental Notice That Initial Market- Based Rate...-referenced proceeding, of Platinum Energy, LLC's application for market-based rate authority, with...

  4. Platinum Neurotoxicity Pharmacogenetics

    PubMed Central

    McWhinney, Sarah R.; Goldberg, Richard M.; McLeod, Howard L.

    2009-01-01

    Cisplatin, carboplatin, and oxaliplatin anticancer drugs are commonly used to treat lung, colorectal, ovarian, breast, head/neck, and genitourinary cancers. However, the efficacy of platinum-based drugs is often compromised because of the substantial risk for severe toxicities, including neurotoxicity. Neurotoxicity can result in both acute and chronic debilitation. Moreover, colorectal cancer patients treated with oxaliplatin more often discontinue therapy due to peripheral neuropathy than for tumor progression, potentially compromising patient benefit. Numerous methods to prevent neurotoxicity have so far proven unsuccessful. In order to circumvent this life-altering side effect, while taking advantage of the antitumor activities of the platinum agents, efforts to identify mechanism-based biomarkers are underway. In this review, we detail findings from the current literature for genetic markers associated with neurotoxicity induced by single agent and combination platinum chemotherapy. These data have the potential for broad clinical implications if mechanistic associations lead to the development of toxicity modulators to minimize the noxious sequelae of platinum chemotherapy. PMID:19139108

  5. Biodistribution of gadolinium-based contrast agents, including gadolinium deposition

    PubMed Central

    Aime, Silvio; Caravan, Peter

    2010-01-01

    The biodistribution of approved gadolinium (Gd) based contrast agents (GBCA) is reviewed. After intravenous injection GBCA distribute in the blood and the extracellular space and transiently through the excretory organs. Preclinical animal studies and the available clinical literature indicate that all these compounds are excreted intact. Elimination tends to be rapid and for the most part, complete. In renally insufficient patients the plasma elimination half-life increases substantially from hours to days depending on renal function. In patients with impaired renal function and nephrogenic systemic fibrosis (NSF), the agents gadodiamide, gadoversetamide, and gadopentetate dimeglumine have been shown to result in Gd deposition in the skin and internal organs. In these cases, it is likely that the Gd is no longer present as the GBCA, but this has still not been definitively shown. In preclinical models very small amounts of Gd are retained in the bone and liver, and the amount retained correlates with the kinetic and thermodynamic stability of the GBCA with respect to Gd release in vitro. The pattern of residual Gd deposition in NSF subjects may be different than that observed in preclinical rodent models. GBCA are designed to be used via intravenous administration. Altering the route of administration and/or the formulation of the GBCA can dramatically alter the biodistribution of the GBCA and can increase the likelihood of Gd deposition. PMID:19938038

  6. Lipid solubility of the platinum group metals Pt, Pd and Rh in dependence on the presence of complexing agents.

    PubMed

    Zimmermann, Sonja; Menzel, Christoph M; Stüben, Doris; Taraschewski, Horst; Sures, Bernd

    2003-01-01

    Investigations on the bioaccumulation of the platinum group metals (PGM) Pt, Pd and Rh in aquatic organisms are of growing interest in environmental research due to the increasing emission of these metals by motor vehicles with catalytic converters. Until now, nothing is known about the possible influence of complexing agents on the bioaccumulation capacity of these precious metals. According to the partition coefficient between 1-octanol and water (POW) as a measure of bioaccumulation, in this study a simple shaking method was performed in order to investigate the effects of different complexing agents (-methionine, thio urea, EDTA, humic substances, bile compounds) on the octanol solubility of the PGM. The results demonstrated a significant influence of all agents used. -Methionine and thio urea decreased the lipid solubility. In contrast, the presence of EDTA, humic substances and especially bile caused a higher transfer of metals in the octanol phase. For most complexing agents tested, the transfer of Pd to the lipid phase was significantly higher compared with Rh and Pt, except for bile acid where the highest octanol solubility was found for Pt. Recent experimental results on PGM accumulation in zebra mussels confirm a high bioaccumulation of Pd which could be predicted from the lipid solubility. PMID:12683977

  7. 28 CFR 552.25 - Use of less-than-lethal weapons, including chemical agents.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., including chemical agents. 552.25 Section 552.25 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF... Use of less-than-lethal weapons, including chemical agents. (a) The Warden may authorize the use of less-than-lethal weapons, including those containing chemical agents, only when the situation is...

  8. 28 CFR 552.25 - Use of less-than-lethal weapons, including chemical agents.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., including chemical agents. 552.25 Section 552.25 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF... Use of less-than-lethal weapons, including chemical agents. (a) The Warden may authorize the use of less-than-lethal weapons, including those containing chemical agents, only when the situation is...

  9. 28 CFR 552.25 - Use of less-than-lethal weapons, including chemical agents.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., including chemical agents. 552.25 Section 552.25 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF... Use of less-than-lethal weapons, including chemical agents. (a) The Warden may authorize the use of less-than-lethal weapons, including those containing chemical agents, only when the situation is...

  10. 28 CFR 552.25 - Use of less-than-lethal weapons, including chemical agents.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., including chemical agents. 552.25 Section 552.25 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF... Use of less-than-lethal weapons, including chemical agents. (a) The Warden may authorize the use of less-than-lethal weapons, including those containing chemical agents, only when the situation is...

  11. Photoactive platinum(ii) β-diketonates as dual action anticancer agents.

    PubMed

    Raza, Md Kausar; Mitra, Koushambi; Shettar, Abhijith; Basu, Uttara; Kondaiah, Paturu; Chakravarty, Akhil R

    2016-08-16

    Platinum(ii) complexes, viz. [Pt(L)(cur)] (1), [Pt(L)(py-acac)] (2) and [Pt(L)(an-acac)] (3), where HL is 4,4'-bis-dimethoxyazobenzene, Hcur is curcumin, Hpy-acac and Han-acac are pyrenyl and anthracenyl appended acetylacetone, were prepared, characterized and their anticancer activities were studied. Complex [Pt(L)(acac)] (4) was used as a control. Complex 1 showed an absorption band at 430 nm (ε = 8.8 × 10(4) M(-1) cm(-1)). The anthracenyl and pyrenyl complexes displayed bands near 390 nm (ε = 3.7 × 10(4) for 3 and 4.4 × 10(4) M(-1) cm(-1) for 2). Complex 1 showed an emission band at 525 nm (Φ = 0.017) in 10% DMSO-DPBS (pH, 7.2), while 2 and 3 were blue emissive (λem = 440 and 435, Φ = 0.058 and 0.045). There was an enhancement in emission intensity on glutathione (GSH) addition indicating diketonate release. The platinum(ii) species thus formed acted as a transcription inhibitor. The released β-diketonate base showed photo-chemotherapeutic activity. The complexes photocleaved plasmid DNA under blue light of 457 nm forming ∼75% nicked circular (NC) DNA with hydroxyl radicals and singlet oxygen as the ROS. Complexes 1-3 were photocytotoxic in skin keratinocyte HaCaT cells giving IC50 of 8-14 μM under visible light (400-700 nm, 10 J cm(-2)), while being non-toxic in the dark (IC50: ∼60 μM). Complex 4 was inactive. Complexes 1-3 generating cellular ROS caused apoptotic cell death under visible light as evidenced from DCFDA and annexin-V/FITC-PI assays. This work presents a novel way to deliver an active platinum(ii) species and a phototoxic β-diketone species to the cancer cells. PMID:27488950

  12. [Mechanism of Platinum Derivatives Induced Kidney Injury].

    PubMed

    Yan, Feifei; Duan, Jianchun; Wang, Jie

    2015-09-20

    Platinum derivatives are the most widely used chemotherapeutic agents to treat solid tumors including ovarian, head and neck, and testicular germ cell tumors, lung cancer, and colorectal cancer. Two major problems exist, however, in the clinic use of platinum derivatives. One is the development of tumor resistance to the drug during therapy, leading to treatment failure. The other is the drug's toxicity such as the cisplatin's nephrotoxicity, which limits the dose that can be administered. This paper describes the mechanism of platinum derivatives induced kidney injury. PMID:26383983

  13. Comparison of the Anti-tumor Effects of Two Platinum Agents (Miriplatin and Fine-Powder Cisplatin)

    SciTech Connect

    Watanabe, Shobu Nitta, Norihisa Ohta, Shinichi Sonoda, Akinaga Otani, Hideji Tomozawa, Yuki Nitta-Seko, Ayumi Tsuchiya, Keiko Tanka, Toyohiko Takahashi, Masashi Murata, Kiyoshi

    2012-04-15

    Purpose: This study was designed to evaluate the anti-tumor effects of miriplatin-lipidol and fine-powder cisplatin-lipiodol suspensions. Methods: Assessment of the cytotoxicity of two drugs was performed: a soluble derivative of miriplatin (DPC) and fine-powder cisplatin. We randomly divided 15 rabbits with transplanted VX2 liver tumors into three equal groups. They were infused via the proper hepatic artery with a miriplatin-lipiodol suspension (ML), a fine-powder cisplatin-lipiodol suspension (CL), or saline (control) and the tumor growth rate was determined on MR images acquired before and 7 days after treatment. The concentration of platinum (PCs) in blood was assayed immediately, and 10, 30, and 60 min, and 24 h and 7 days after drug administration. Its concentration in tumor and surrounding normal liver tissues was determined at 7 days postadministration. Results: At high concentrations, fine-powder cisplatin exhibited stronger cytotoxicity than DPC. At low concentrations, both agents manifested weak cytotoxicity. While there was no difference between the tumor growth rate of the ML and the CL groups, the difference between the controls and ML- and CL-treated rabbits was significant. The blood PCs peaked at 10 min and then gradually decreased over time. On the other hand, no platinum was detected at any point after the administration of ML. There was no difference between the ML and CL groups in the PCs in tumor tissues; however, in normal hepatic tissue, the PCs were higher in ML- than CL-treated rabbits. Conclusions: We confirmed the anti-tumor effect of ML and CL. There was no significant difference between the anti-tumor effect of ML and CL at 7 days postadministration.

  14. Potent and non-specific inhibition of cytochrome P450 by JM216, a new oral platinum agent.

    PubMed Central

    Ando, Y.; Shimizu, T.; Nakamura, K.; Mushiroda, T.; Nakagawa, T.; Kodama, T.; Kamataki, T.

    1998-01-01

    Bis-acetato-ammine-dichloro-cyclohexylamine-platinum (IV), JM216, is the first antineoplastic platinum compound that can be given to patients orally. Several phase II clinical trials of JM216 monotherapy have already been reported. However, no information on the potential drug interactions caused by JM216 is available. In this study, the capacity of JM216 to inhibit cytochrome P450 (CYP) in human liver microsomes was investigated by measuring the inhibition potential (IC50 and Ki) on prototype reactions. Specific substrates of CYP included testosterone (catalysed by CYP3A4), paclitaxel (CYP2C8), 7-ethoxyresorufin (CYP1A1, CYP1A2), coumarin (CYP2A6), aniline (CYP2E1) and (+/-)-bufuralol (CYP2D6). JM216 inhibited the catalytic activities of CYP isozymes. The IC50 values were between 0.3 microM and 10 microM, indicating strong and non-specific inhibitory effects of JM216. The inhibition occurred in a non-competitive manner, and the Ki value was 1.0 and 0.9 microM for metabolite formation of testosterone and paclitaxel respectively. Therefore, some in vivo studies should be conducted to determine whether or not there is a correlation between in vivo and in vitro results. PMID:9820175

  15. Sec61β Controls Sensitivity to Platinum-Containing Chemotherapeutic Agents through Modulation of the Copper-Transporting ATPase ATP7A

    PubMed Central

    Larson, Christopher A.; Manorek, Gerald; Adams, Preston; Howell, Stephen B.

    2012-01-01

    The Sec61 protein translocon is a multimeric complex that transports proteins across lipid bilayers. We discovered that the Sec61β subunit modulates cellular sensitivity to chemotherapeutic agents, particularly the platinum drugs. To investigate the mechanism, expression of Sec61β was constitutively knocked down in 2008 ovarian cancer cells. Sec61β knockdown (KD) resulted in 8-, 16.8-, and 9-fold resistance to cisplatin (cDDP), carboplatin, and oxaliplatin, respectively. Sec61β KD reduced the cellular accumulation of cDDP to 67% of that in parental cells. Baseline copper levels, copper uptake, and copper cytotoxicity were also reduced. Because copper transporters and chaperones regulate platinum drug accumulation and efflux, their expression in 2008 Sec61β-KD cells was analyzed; ATP7A was found to be 2- to 3-fold overexpressed, whereas there was no change in ATP7B, ATOX1, CTR1, or CTR2 levels. Cells lacking ATP7A did not exhibit increased cDDP resistance upon knockdown of Sec61β. Sec61β-KD cells also exhibited altered ATP7A cellular distribution. We conclude that Sec61β modulates the cytotoxicity of many chemotherapeutic agents, with the largest effect being on the platinum drugs. This modulation occurs through effects of Sec61β on the expression and distribution of ATP7A, which was shown previously to control platinum drug sequestration and cytotoxicity. PMID:22710939

  16. Synthesis, Characterization, and Evaluation of cis-Diphenyl Pyridineamine Platinum(II) Complexes as Potential Anti-Breast Cancer Agents

    PubMed Central

    Guevara, Priscilla; Ramirez, Verenice; Metta-Magaña, Alejandro J.; Villagrán, Dino; Varela-Ramirez, Armando; Das, Siddhartha; Nuñez, Jose E.

    2015-01-01

    Although cisplatin is considered as an effective anti-cancer agent, it has shown limitations and may produce toxicity in patients. Therefore, we synthesized two cis-dichlorideplatinum(II) compounds (13 and 14) composed of meta- and para-N,N-diphenyl pyridineamine ligands through a reaction of the amine precursors and PtCl2 with respective yields of 16% and 47%. We hypothesized that compounds 13 and 14, with lipophilic ligands, should transport efficiently in cancer cells and demonstrate more effectiveness than cisplatin. When tested for biological activity, compounds 13 and 14 were found to inhibit the growth of MCF 7 and MDA-MB-231 cells (IC50s 1 ± 0.4 μM and 1 ± 0.2 μM for 13 and 14, respectively, and IC50 7.5 ± 1.3 μM for compound 13 and 1 ± 0.3 μM for compound 14). Incidentally, these doses were found to be lower than cisplatin doses (IC50 5 ± 0.7 μM for MCF 7 and 10 ± 1.1 μM for MDA-MB-231). Similar to cisplatin, 13 and 14 interacted with DNA and induced apoptosis. However, unlike cisplatin, they blocked the migration of MDA-MB-231 cells suggesting that in addition to apoptotic and DNA-binding capabilities, these compounds are useful in blocking the metastatic migration of breast cancer cells. To delineate the mechanism of action, computer-aided analyses (DFT calculations) were conducted for compound 13. Results indicate that in vivo, the pyridineamine ligands are likely to dissociate from the complex, forming a platinum DNA adduct with anti-proliferative activity. These results suggest that complexes 13 and 14 hold promise as potential anti-cancer agents. PMID:24737042

  17. Coating Carbon Fibers With Platinum

    NASA Technical Reports Server (NTRS)

    Effinger, Michael R.; Duncan, Peter; Coupland, Duncan; Rigali, Mark J.

    2007-01-01

    A process for coating carbon fibers with platinum has been developed. The process may also be adaptable to coating carbon fibers with other noble and refractory metals, including rhenium and iridium. The coated carbon fibers would be used as ingredients of matrix/fiber composite materials that would resist oxidation at high temperatures. The metal coats would contribute to oxidation resistance by keeping atmospheric oxygen away from fibers when cracks form in the matrices. Other processes that have been used to coat carbon fibers with metals have significant disadvantages: Metal-vapor deposition processes yield coats that are nonuniform along both the lengths and the circumferences of the fibers. The electrical resistivities of carbon fibers are too high to be compatible with electrolytic processes. Metal/organic vapor deposition entails the use of expensive starting materials, it may be necessary to use a furnace, and the starting materials and/or materials generated in the process may be hazardous. The present process does not have these disadvantages. It yields uniform, nonporous coats and is relatively inexpensive. The process can be summarized as one of pretreatment followed by electroless deposition. The process consists of the following steps: The surfaces of the fiber are activated by deposition of palladium crystallites from a solution. The surface-activated fibers are immersed in a solution that contains platinum. A reducing agent is used to supply electrons to effect a chemical reduction in situ. The chemical reduction displaces the platinum from the solution. The displaced platinum becomes deposited on the fibers. Each platinum atom that has been deposited acts as a catalytic site for the deposition of another platinum atom. Hence, the deposition process can also be characterized as autocatalytic. The thickness of the deposited metal can be tailored via the duration of immersion and the chemical activity of the solution.

  18. A Platinum-Dithiolene Monoanionic Salt Exhibiting Multiproperties, Including Room-Temperature Proton-Dependent Solution Luminescence.

    PubMed

    Attar, Salahuddin; Espa, Davide; Artizzu, Flavia; Mercuri, M Laura; Serpe, Angela; Sessini, Elisa; Concas, Giorgio; Congiu, Francesco; Marchiò, Luciano; Deplano, Paola

    2016-06-01

    The platinum salt C[PtL2], where C = [(R)-Ph(Me)HC*-NMe3](+) and [PtL2](-) = radical monoanion based on [4', 5': 5, 6][1, 4]dithiino[2,3-b]quinoxaline-1',3'dithiolato, shows a variety of properties both in solution and in the solid state thanks to the electronic and/or structural features of the ligand. The complex crystallizes in the chiral space group P1 due to the presence of the enantiopure cation (R)-Ph(Me)HC*-NMe3(+), and it shows paramagnetic behavior relatable to the [PtL2](-) radical monoanion. This anionic complex is redox active and shows a strong near-infrared absorbance peak at 1085 nm tunable with the oxidation state of the complex. This complex exhibits a proton-dependent emission at 572 nm in solution at room temperature. The excitation band corresponds to the HOMO-1 (π-orbitals of the S2C2S2 system) → LUMO (π-orbitals of the quinoxaline and benzene-like moieties) transition suggesting that emission is mainly ligand centered in character. The luminescent properties are highly unusual, since the emission falls well above the energy of the lowest energy absorption (anti-Kasha behavior). Joint experimental and density functional theory (DFT) and time-dependent DFT studies are discussed to provide a satisfactory structure/property relationship. PMID:27163727

  19. pH-dependent release of trace elements including platinum group elements (PGEs) from gasoline and diesel catalysts

    NASA Astrophysics Data System (ADS)

    Sucha, Veronika; Mihaljevic, Martin; Ettler, Vojtech; Strnad, Ladislav

    2014-05-01

    The release of trace metals and platinum group elements (PGEs) from automobile exhaust catalysts represents a remarkable source of higly dispersed environmental contamination. Especially, PGEs have shown increasing research interest due to their possible bioaccessibility. In our research, we focused on leaching behaviour of trace metals from gasoline and diesel automobile catalysts. While catalysts for gasoline engines contain a mixture of Pt-Pd-Rh or Pd-Rh, catalysts for diesel engines are composed only of Pt. We used dust from two crushed gasoline and two crushed diesel catalysts (new and aged). The dust of gasoline catalysts contains significant concentrations of Pt (700 mg.kg-1), Pd (11 000 mg.kg-1) and Rh (700 mg.kg-1). And the dust of diesel catalysts are composed of Pt (3 900 mg.kg-1) and they contains negligible amounts of Pd dan Rh (< 0.5 mg.kg-1, < 0.1 mg.kg-1, respectively). To evaluate leaching of trace metals from dust we used pH-stat leaching test according to the European standard CEN/TS 14997. The concentrations of cations: PGEs (Pt, Pd a Rh), K, Na, Ca, Mg, Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, La and Ce were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS), and anions: F-, Cl-, SO42- and NO3- by high-performance liquid chromatography. Although the dusts from catalysts were relatively stable to acid/base influence, the leaching of trace metals from catalysts showed a dependence on pH. Generally, the highest concentrations were released under acidic conditions. The leaching of PGEs was higher for Pt in diesel catalysts and for Pd and Rh in gasoline catalysts. The highest concentrations of Zn and Pb were observed in old catalysts. The rare earth metals were released more from gasoline catalysts. Catalysts particles represent health risk especially with respect to their PGEs contents.

  20. Mass spectrometry in identification of ecotoxicants including chemical and biological warfare agents.

    PubMed

    Lebedev, Albert T

    2005-09-01

    Mass spectrometry is a unique tool to detect and identify trace levels of organic and bioorganic compounds as well as microorganisms in the environment. The range of potential chemical warfare (CW) and biological warfare (BW) agents is very broad. An important advantage of mass spectrometry over other techniques involves potential for full spectrum detection of chemical and biological agents including mid-spectrum materials (i.e. bioactive peptides, toxins, etc.) for which biological approaches are inadequate. Being very fast (seconds and minutes), extremely sensitive (zeptomoles 10(-21)), and informative (detailed qualitative and quantitative composition of mixtures containing hundreds of chemicals), mass spectrometry is a principal analytical tool at the sites of destruction of CW. Due to its unique features, mass spectrometry is applied not only for the detection of CW agents, but for the analysis of products of metabolism and degradation of these agents in organisms or environment as well. The present paper deals with some examples of successful application of mass spectrometry for the analyses of ecotoxicants, chemical warfare agents, explosives, and microorganisms including biology warfare agents. PMID:16024060

  1. Mass spectrometry in identification of ecotoxicants including chemical and biological warfare agents

    SciTech Connect

    Lebedev, Albert T. . E-mail: lebedev@org.chem.msu.ru

    2005-09-01

    Mass spectrometry is a unique tool to detect and identify trace levels of organic and bioorganic compounds as well as microorganisms in the environment. The range of potential chemical warfare (CW) and biological warfare (BW) agents is very broad. An important advantage of mass spectrometry over other techniques involves potential for full spectrum detection of chemical and biological agents including mid-spectrum materials (i.e. bioactive peptides, toxins, etc.) for which biological approaches are inadequate. Being very fast (seconds and minutes), extremely sensitive (zeptomoles 10{sup -21}), and informative (detailed qualitative and quantitative composition of mixtures containing hundreds of chemicals), mass spectrometry is a principal analytical tool at the sites of destruction of CW. Due to its unique features, mass spectrometry is applied not only for the detection of CW agents, but for the analysis of products of metabolism and degradation of these agents in organisms or environment as well. The present paper deals with some examples of successful application of mass spectrometry for the analyses of ecotoxicants, chemical warfare agents, explosives, and microorganisms including biology warfare agents.

  2. Pre-association of polynuclear platinum anticancer agents on a protein, human serum albumin. Implications for drug design†

    PubMed Central

    Montero, Eva I.; Benedetti, Brad T.; Mangrum, John B.; Oehlsen, Michael J.; Qu, Yun; Farrell, Nicholas P.

    2009-01-01

    The interactions of polynuclear platinum complexes with human serum albumin were studied. The compounds examined were the “non-covalent” analogs of the trinuclear BBR3464 as well as the dinuclear spermidine-bridged compounds differing in only the presence or absence of a central -NH2-+ (BBR3571 and analogs). Thus, closely-related compounds could be compared. Evidence for pre-association, presumably through electrostatic and hydrogen-bonding, was obtained from fluorescence and circular dichroism spectroscopy and Electrospray Ionization Mass Spectrometry (ESI-MS). In the case of those compounds containing Pt-Cl bonds, further reaction took place presumably through displacement by sulfur nucleophiles. The implications for protein pre-association and plasma stability of polynuclear platinum compounds are discussed. PMID:17992278

  3. Recruitment of trimeric proliferating cell nuclear antigen by G1-phase cyclin-dependent kinases following DNA damage with platinum-based antitumour agents

    PubMed Central

    He, G; Kuang, J; Koomen, J; Kobayashi, R; Khokhar, A R; Siddik, Z H

    2013-01-01

    Background: In cycling tumour cells, the binary cyclin-dependent kinase Cdk4/cyclin D or Cdk2/cyclin E complex is inhibited by p21 following DNA damage to induce G1 cell-cycle arrest. However, it is not known whether other proteins are also recruited within Cdk complexes, or their role, and this was investigated. Methods: Ovarian A2780 tumour cells were exposed to the platinum-based antitumour agent 1R,2R-diaminocyclohexane(trans-diacetato)(dichloro)platinum(IV) (DAP), which preferentially induces G1 arrest in a p21-dependent manner. The Cdk complexes were analysed by gel filtration chromatography, immunoblot and mass spectrometry. Results: The active forms of Cdk4 and Cdk2 complexes in control tumour cells have a molecular size of ∼140 kDa, which increased to ∼290 kDa when inhibited following G1 checkpoint activation by DAP. Proteomic analysis identified Cdk, cyclin, p21 and proliferating cell nuclear antigen (PCNA) in the inhibited complex, and biochemical studies provided unequivocal evidence that the increase in ∼150 kDa of the inhibited complex is consistent with p21-dependent recruitment of PCNA as a trimer, likely bound to three molecules of p21. Although p21 alone was sufficient to inhibit the Cdk complex, PCNA was critical for stabilising p21. Conclusion: G1 Cdk complexes inhibited by p21 also recruit PCNA, which inhibits degradation and, thereby, prolongs activity of p21 within the complex. PMID:24104967

  4. In Vitro and In Vivo Studies of Non-Platinum-Based Halogenated Compounds as Potent Antitumor Agents for Natural Targeted Chemotherapy of Cancers

    PubMed Central

    Lu, Qing-Bin; Zhang, Qin-Rong; Ou, Ning; Wang, Chun-Rong; Warrington, Jenny

    2015-01-01

    Based on a molecular-mechanism-based anticancer drug discovery program enabled by an innovative femtomedicine approach, we have found a previously unknown class of non-platinum-based halogenated molecules (called FMD compounds) as potent antitumor agents for effective treatment of cancers. Here, we present in vitro and in vivo studies of the compounds for targeted chemotherapy of cervical, breast, ovarian, and lung cancers. Our results show that these FMD agents led to DNA damage, cell cycle arrest in the S phase, and apoptosis in cancer cells. We also observed that such a FMD compound caused an increase of reduced glutathione (GSH, an endogenous antioxidant) levels in human normal cells, while it largely depleted GSH in cancer cells. We correspondingly found that these FMD agents exhibited no or little toxicity toward normal cells/tissues, while causing significant cytotoxicity against cancer cells, as well as suppression and delay in tumor growth in mouse xenograft models of cervical, ovarian, breast and lung cancers. These compounds are therefore a previously undiscovered class of potent antitumor agents that can be translated into clinical trials for natural targeted chemotherapy of multiple cancers. PMID:26351651

  5. Cis-Diammine(Pyridine)Chloroplatinum(II), a Monofunctional Platinum(II) Antitumor Agent: Uptake, Structure, Function, And Prospects

    SciTech Connect

    Lovejoy, K.S.; Todd, R.C.; Zhang, S.; McCormick, M.S.; D'Aquino, J.A.; Reardon, J.T.; Sancar, A.; Giacomini, K.M.; Lippard, S.J.

    2009-05-19

    We have identified unique chemical and biological properties of a cationic monofunctional platinum(II) complex, cis-diammine(pyridine)chloroplatinum(II), cis-[Pt(NH{sub 3}){sub 2}(py)Cl]{sup +} or cDPCP, a coordination compound previously identified to have significant anticancer activity in a mouse tumor model. This compound is an excellent substrate for organic cation transporters 1 and 2, also designated SLC22A1 and SLC22A2, respectively. These transporters are abundantly expressed in human colorectal cancers, where they mediate uptake of oxaliplatin, cis-[Pt(DACH)(oxalate)] (DACH = trans-R,R-1,2-diaminocyclohexane), an FDA-approved first-line therapy for colorectal cancer. Unlike oxaliplatin, however, cDPCP binds DNA monofunctionally, as revealed by an x-ray crystal structure of cis-{l_brace}Pt(NH{sub 3}){sub 2}(py){r_brace}{sup 2+} bound to the N7 atom of a single guanosine residue in a DNA dodecamer duplex. Although the quaternary structure resembles that of B-form DNA, there is a base-pair step to the 5{prime} side of the Pt adduct with abnormally large shift and slide values, features characteristic of cisplatin intrastrand cross-links. cDPCP effectively blocks transcription from DNA templates carrying adducts of the complex, unlike DNA lesions of other monofunctional platinum(II) compounds like {l_brace}Pt(dien){r_brace}{sup 2+}. cDPCP-DNA adducts are removed by the nucleotide excision repair apparatus, albeit much less efficiently than bifunctional platinum-DNA intrastrand cross-links. These exceptional characteristics indicate that cDPCP and related complexes merit consideration as therapeutic options for treating colorectal and other cancers bearing appropriate cation transporters.

  6. Chiral Platinum(II) Complexes Featuring Phosphine and Chloroquine Ligands as Cytotoxic and Monofunctional DNA-Binding Agents.

    PubMed

    Villarreal, Wilmer; Colina-Vegas, Legna; Rodrigues de Oliveira, Clayton; Tenorio, Juan C; Ellena, Javier; Gozzo, Fábio C; Cominetti, Marcia Regina; Ferreira, Antonio G; Ferreira, Marco Antonio Barbosa; Navarro, Maribel; Batista, Alzir A

    2015-12-21

    Chiral molecules in nature are involved in many biological events; their selectivity and specificity make them of great interest for understanding the behavior of bioactive molecules, by providing information about the chiral discrimination. Inspired by these conformational properties, we present the design and synthesis of novel chiral platinum(II) complexes featuring phosphine and chloroquine ligands with the general formula [PtCl(P)2(CQ)]PF6 (where (P)2 = triphenylphosphine (PPh3) (5), 1,3-bis(diphenylphosphine)propane (dppp) (6), 1,4-bis(diphenylphosphine)butane (dppb) (7), 1,1'-bis(diphenylphosphine)ferrocene (dppf) (8), and CQ = chloroquine] and their precursors of the type [PtCl2(P)2] are described. The complexes were characterized by elemental analysis, absorption spectroscopy in the infrared and ultraviolet-visible (UV-vis) regions, multinuclear ((1)H, (13)C, (31)P, (15)N, and (195)Pt) NMR spectroscopy, cyclic voltammetry, and mass spectrometry (in the case of chloroquine complexes). The interactions of the new platinum-chloroquine complexes with both albumin (BSA), using fluorescence spectroscopy, and DNA, by four widely reported methods were also evaluated. These experiments showed that these Pt-CQ complexes interact strongly with DNA and have high affinities for BSA, in contrast to CQ and CQDP (chloroquine diphosphate), which interact weakly with these biomolecules. Additional assays were performed in order to investigate the cytotoxicity of the platinum complexes against two healthy cell lines (mouse fibroblasts (L929) and the Chinese hamster lung (V79-4)) and four tumor cell lines (human breast (MDA-MB-231 and MCF-7), human lung (A549), and human prostate (DU-145)). The results suggest that the Pt-CQ complexes are generally more cytotoxic than the free CQ, showing that they are promising as anticancer drugs. PMID:26606142

  7. Nanoscale platinum printing on insulating substrates.

    PubMed

    O'Connell, C D; Higgins, M J; Sullivan, R P; Jamali, S S; Moulton, S E; Wallace, G G

    2013-12-20

    The deposition of noble metals on soft and/or flexible substrates is vital for several emerging applications including flexible electronics and the fabrication of soft bionic implants. In this paper, we describe a new strategy for the deposition of platinum electrodes on a range of materials, including insulators and flexible polymers. The strategy is enabled by two principle advances: (1) the introduction of a novel, low temperature strategy for reducing chloroplatinic acid to platinum using nitrogen plasma; (2) the development of a chloroplatinic acid based liquid ink formulation, utilizing ethylene glycol as both ink carrier and reducing agent, for versatile printing at nanoscale resolution using dip-pen nanolithography (DPN). The ink formulation has been printed and reduced upon Si, glass, ITO, Ge, PDMS, and Parylene C. The plasma treatment effects reduction of the precursor patterns in situ without subjecting the substrate to destructively high temperatures. Feature size is controlled via dwell time and degree of ink loading, and platinum features with 60 nm dimensions could be routinely achieved on Si. Reduction of the ink to platinum was confirmed by energy dispersive x-ray spectroscopy (EDS) elemental analysis and x-ray diffraction (XRD) measurements. Feature morphology was characterized by optical microscopy, SEM and AFM. The high electrochemical activity of individually printed Pt features was characterized using scanning electrochemical microscopy (SECM). PMID:24270681

  8. Nanoscale platinum printing on insulating substrates

    NASA Astrophysics Data System (ADS)

    O'Connell, C. D.; Higgins, M. J.; Sullivan, R. P.; Jamali, S. S.; Moulton, S. E.; Wallace, G. G.

    2013-12-01

    The deposition of noble metals on soft and/or flexible substrates is vital for several emerging applications including flexible electronics and the fabrication of soft bionic implants. In this paper, we describe a new strategy for the deposition of platinum electrodes on a range of materials, including insulators and flexible polymers. The strategy is enabled by two principle advances: (1) the introduction of a novel, low temperature strategy for reducing chloroplatinic acid to platinum using nitrogen plasma; (2) the development of a chloroplatinic acid based liquid ink formulation, utilizing ethylene glycol as both ink carrier and reducing agent, for versatile printing at nanoscale resolution using dip-pen nanolithography (DPN). The ink formulation has been printed and reduced upon Si, glass, ITO, Ge, PDMS, and Parylene C. The plasma treatment effects reduction of the precursor patterns in situ without subjecting the substrate to destructively high temperatures. Feature size is controlled via dwell time and degree of ink loading, and platinum features with 60 nm dimensions could be routinely achieved on Si. Reduction of the ink to platinum was confirmed by energy dispersive x-ray spectroscopy (EDS) elemental analysis and x-ray diffraction (XRD) measurements. Feature morphology was characterized by optical microscopy, SEM and AFM. The high electrochemical activity of individually printed Pt features was characterized using scanning electrochemical microscopy (SECM).

  9. Trans- and cis-2-phenylindole platinum(II) complexes as cytotoxic agents against human breast adenocarcinoma cell lines

    NASA Astrophysics Data System (ADS)

    Tomé, Maria; López, Concepción; González, Asensio; Ozay, Bahadir; Quirante, Josefina; Font-Bardía, Mercè; Calvet, Teresa; Calvis, Carme; Messeguer, Ramon; Baldomá, Laura; Badía, Josefa

    2013-09-01

    The synthesis and characterization of the new 2-phenylindole derivative: C8H3N-2-C6H5-3NOMe-5OMe (3c) and the trans- and cis-isomers of [Pt(3c)Cl2(DMSO)] complexes (4c and 5c, respectively) are described. The crystal structures of 4c·CH2Cl2 and 5c confirm: (a) the existence of a Pt-Nindole bond, (b) the relative arrangement of the Cl- ligands [trans- (in 4c) or cis- (in 5c)] and (c) the anti-(E) configuration of the oxime. The cytotoxic assessment of C8H3N-2-(C6H4-4‧R1)-3NOMe-5R2 [with R1 = R2 = H (3a); R1 = Cl, R2 = H (3b) and R1 = H, R2 = OMe (3c)] and the geometrical isomers of [Pt(L)Cl2(DMSO)] with L = 3a-3c [trans- (4a-4c) and cis- (5a-5c), respectively] against human breast adenocarcinoma cell lines (MDA-MB231 and MCF-7) is also reported and reveals that all the platinum(II) complexes (except 4a) are more cytotoxic than cisplatin in front of the MCF7 cell line. Electrophoretic DNA migration studies of the synthesized compounds in the absence and in the presence of topoisomerase-I have been performed, in order to get further insights into their mechanism of action.

  10. Polymorphic transporters and platinum pharmacodynamics

    PubMed Central

    Sprowl, Jason A.; Ness, Rachel A.; Sparreboom, Alex

    2013-01-01

    Summary Several solute carriers and ATP-binding cassette transporters have been implicated in the influx or efflux of platinum-based chemotherapeutic agents such as cisplatin, carboplatin, and oxaliplatin. Given that many of these proteins are highly polymorphic, the genetic status of these proteins could be an important contributor to the extensive interindividual pharmacokinetic variability associated with the clinical use of these agents. In this review article, we provide an updated overview of the various transporters that have shown promise in animal models or patient populations in facilitating the movement of platinum-based agents across cell membranes, and how their function is associated with drug disposition or pharmacodynamic effects. PMID:22986709

  11. Genome Sequencing of Four Strains of Rickettsia prowazekii, the Causative Agent of Epidemic Typhus, Including One Flying Squirrel Isolate.

    PubMed

    Bishop-Lilly, Kimberly A; Ge, Hong; Butani, Amy; Osborne, Brian; Verratti, Kathleen; Mokashi, Vishwesh; Nagarajan, Niranjan; Pop, Mihai; Read, Timothy D; Richards, Allen L

    2013-01-01

    Rickettsia prowazekii is a notable intracellular pathogen, the agent of epidemic typhus, and a potential biothreat agent. We present here whole-genome sequence data for four strains of R. prowazekii, including one from a flying squirrel. PMID:23814035

  12. Inhibition of DNA Synthesis by a Platinum-Acridine Hybrid Agent Leads to Potent Cell Kill in Non-Small Cell Lung Cancer.

    PubMed

    Smyre, Christopher L; Saluta, Gilda; Kute, Timothy E; Kucera, Gregory L; Bierbach, Ulrich

    2011-08-31

    The platinum-acridine anti-cancer agent [PtCl(en)(LH)](NO(3))(2) (1) (en = ethane-1,2-diamine, LH = N-(2-(acridin-9-ylamino)ethyl)-N-methylpropionimidamide, acridinium cation) and the clinical drug cisplatin were studied in chemoresistant non-small cell lung cancer (NSCLC) cell lines for their cytotoxic potency and cell-kill mechanisms. In the three cell lines tested (NCI-H460, NCI-H522, and NCI-H1435) compound 1 shows a pronounced cytotoxic enhancement of 40-200-fold compared to cisplatin at inhibitory concentrations reaching the low-nanomolar range. Based on changes in cell adhesion and cell morphology, monitored in real time by impedance measurements, compound 1 kills NCI-H460 cells significantly more efficiently than cisplatin at equitoxic concentrations. Flow cytometry analysis of NCI-H460 cells reveals a robust S-phase arrest of cells treated with compound 1, whereas cells treated with cisplatin progress to G2/M of the cell cycle. A pronounced inhibition of DNA replication in 75% of viable cells is observed in NCI-H460 cells treated with compound 1 at an IC(90) molar concentration for 48 h, based on the reduced incorporation of the fluorophore-clickable nucleoside analogue 5-ethynyl-2´-deoxyuridine (EdU) into newly synthesized DNA. The distinct cell-cycle perturbations and cell-kill potential of compound 1 are discussed in the light of the DNA interactions of this agent and its potential to overcome cisplatin resistance in NSCLC. PMID:22328962

  13. A randomised, phase II trial of the DNA-hypomethylating agent 5-aza-2′-deoxycytidine (decitabine) in combination with carboplatin vs carboplatin alone in patients with recurrent, partially platinum-sensitive ovarian cancer

    PubMed Central

    Glasspool, R M; Brown, R; Gore, M E; Rustin, G J S; McNeish, I A; Wilson, R H; Pledge, S; Paul, J; Mackean, M; Hall, G D; Gabra, H; Halford, S E R; Walker, J; Appleton, K; Ullah, R; Kaye, S

    2014-01-01

    Background: Our previous laboratory and clinical data suggested that one mechanism underlying the development of platinum resistance in ovarian cancer is the acquisition of DNA methylation. We therefore tested the hypothesis that the DNA hypomethylating agent 5-aza-2′-deoxycytodine (decitabine) can reverse resistance to carboplatin in women with relapsed ovarian cancer. Methods: Patients progressing 6–12 months after previous platinum therapy were randomised to decitabine on day 1 and carboplatin (AUC 6) on day 8, every 28 days or carboplatin alone. The primary objective was response rate in patients with methylated hMLH1 tumour DNA in plasma. Results: After a pre-defined interim analysis, the study closed due to lack of efficacy and poor treatment deliverability in 15 patients treated with the combination. Responses by GCIG criteria were 9 out of 14 vs 3 out of 15 and by RECIST were 6 out of 13 vs 1 out of 12 for carboplatin and carboplatin/decitabine, respectively. Grade 3/4 neutropenia was more common with the combination (60% vs 15.4%) as was G2/3 carboplatin hypersensitivity (47% vs 21%). Conclusions: With this schedule, the addition of decitabine appears to reduce rather than increase the efficacy of carboplatin in partially platinum-sensitive ovarian cancer and is difficult to deliver. Patient-selection strategies, different schedules and other demethylating agents should be considered in future combination studies. PMID:24642620

  14. Platinum(II) and Palladium(II) Complexes of Pyridine-2-Carbaldehyde Thiosemicarbazone as Alternative Antiherpes Simplex Virus Agents

    PubMed Central

    Kovala-Demertzi, D.; Varadinova, T.; Genova, P.; Souza, P.; Demertzis, M. A.

    2007-01-01

    The cytotoxicity and the antivirus activity of Pd(II) and Pt(II) complexes with pyridine-2-carbaldehyde thiosemicarbazone (HFoTsc) against HSV replication were evaluated on four HSV strains—two wt strains Victoria (HSV-1) and BJA (HSV-2) and two ACVR mutants with different tk gene mutations R-100 (TKA, HSV-1) and PU (TKN, HSV-2). The experiments were performed on continuous MDBK cells and four HSV 1 and HSV 2 strains were used, two sensitive to acyclovir and two resistant mutants. The five complexes of HFoTsc, [Pt(FoTsc)Cl], [Pt(FoTsc)(H2FoTsc)]Cl2, [Pt(FoTsc)2], [Pd(FoTsc)(H2FoTsc)]Cl2, and [Pd(FoTsc)2], were found to be effective inhibitors of HSV replication. The most promising, active, and selective anti-HSV agent was found to be complex [Pt(FoTsc)(H2FoTsc)]Cl2. This complex could be useful in the treatment of HSV infections, since it is resistant to ACV mutants. PCR study of immediate early 300 bp ReIV Us1 region reveals that the complex [Pt(FoTsc)(H2FoTsc)]Cl2 specifically suppressed wt HSV-1 genome 2 hours after the infection, not inducing apoptosis/necrosis on the 8 hours after virus infection. The target was found to be most probably the viral, instead of the host cell DNA. PMID:17541481

  15. [Platinum antitumor complexes].

    PubMed

    Bonetti, Andrea; Giuliani, Jacopo; Muggia, Franco

    2015-12-01

    In the last 50 years the oncology has experienced remarkable changes resulting in transforming malignant germ-cell testicular tumors from highly fatal to nearly uniformly cured neoplasms. This clinical landmark was justly attributed to the identification of cisplatin by Barnett Rosenberg in his experiments dating to 1965. On this 50th anniversary of this discovery, one is reminded of the following key aspects in cancer therapeutics: 1) the life-story of Barnett Rosenberg and his legacy that included organizing nearly quadrennial "platinum" meetings incorporating advances in cancer biology into evolving therapeutic strategies; 2) the search for less toxic analogs of cisplatin leading to the development of carboplatin; 3) clinical research into attenuation of cisplatin toxicities; 4) oxaliplatin and the expansion of the therapeutic spectrum of platinum compounds; and 5) the ongoing multifaceted investigations into the problem of "platinum resistance". PMID:26780071

  16. Method for forming porous platinum films

    DOEpatents

    Maya, Leon

    2000-01-01

    A method for forming a platinum film includes providing a substrate, sputtering a crystalline platinum oxide layer over at least a portion of the substrate, and reducing the crystalline platinum oxide layer to form the platinum film. A device includes a non-conductive substrate and a platinum layer having a density of between about 2 and 5 g/cm.sup.3 formed over at least a portion of the non-conductive substrate. The platinum films produced in accordance with the present invention provide porous films suitable for use as electrodes, yet require few processing steps. Thus, such films are less costly. Such films may be formed on both conductive and non-conductive substrates. While the invention has been illustrated with platinum, other metals, such as noble metals, that form a low density oxide when reactively sputtered may also be used.

  17. Luminescent Platinum Compounds: From Molecules to OLEDs

    NASA Astrophysics Data System (ADS)

    Murphy, Lisa; Williams, J. A. Gareth

    Around 30 years ago, much of the research into platinum coordination chemistry was being driven either by research into one-dimensional, electrically conducting molecular materials exploiting the stacking interactions of planar complexes, or by the unprecedented success of cis-Pt(NH3)2Cl2 (cisplatin) as an anticancer agent. At that time, a number of simple platinum(II) compounds were known to be photoluminescent at low temperature or in the solid state, but almost none in fluid solution at room temperature. Since that time, several families of complexes have been discovered that are brightly luminescent, and a number of investigations have shed light on the factors that govern the luminescence efficiencies of Pt(II) complexes. Over the past decade, such studies have been spurred on by the potential application of triplet-emitting metal complexes as phosphors in organic light-emitting devices (OLEDs), where their ability to trap otherwise wasted triplet states can lead to large gains in efficiency. In this contribution, we take a chemist's perspective of the field, overviewing in the first instance the factors that need to be taken into account in the rational design of highly luminescent platinum(II) complexes, and the background to their use in OLEDs. We then consider in more detail the properties of some individual classes, highlighting work from the past 3 years, and including selected examples of their utility in OLEDs and other applications.

  18. Pharmacokinetics and tissue distribution of novel platinum containing anticancer agent BP‐C1 studied in rabbits using sector field inductively coupled plasma mass spectrometry

    PubMed Central

    Navolotskii, Denis V.; Ivanenko, Natalya B.; Fedoros, Elena I.; Panchenko, Andrey V.

    2015-01-01

    A method of platinum quantification in whole blood samples after microwave digestion using sector field inductively coupled plasma mass spectrometry has been developed. The following analytical figures of merit have been established: limit of detection 1.1 µg/L for blood samples, dynamic range 3.6–200 µg/L, intra‐day precision (relative standard deviation, n = 9) did not exceed 5%. Spiked samples were analyzed for method validation. The method was used for pharmacokinetics studies of a novel anti‐cancer drug BP‐С1, a complex of cis‐configured platinum and benzene‐poly‐carboxylic acids. Main pharmacokinetic parameters (area under curve, maximum concentration, clearance, half‐life times for α‐ and β‐phase) were estimated for two dosage forms of BP‐C1 0.05 and 0.125 mass %. Pharmacokinetic curves were assessed for single and course administration. Studies were performed using rabbits (n = 6) as a model. BP‐C1 was injected intramuscularly. The study established dose proportionality of the tested dosage forms and suggested clinical dosing schedule: 5 days of injections followed by 2 days’ break. Platinum tissue distribution was studied in tissue samples collected 20 days after the last injection. Predominant platinum accumulation was observed in kidneys, liver, and muscles near injection site. ‘Slow’ phase of platinum excretion kinetics may be related to the muscles at the injection site. © 2015 The Authors. Drug Testing and Analysis published by John Wiley & Sons Ltd. PMID:26061351

  19. Non-platinum-based chemotherapy for treatment of advanced gastric cancer: 5-fluorouracil, taxanes, and irinotecan.

    PubMed

    Kang, Byung Woog; Kim, Jong Gwang; Kwon, Oh-Kyoung; Chung, Ho Young; Yu, Wansik

    2014-05-14

    Despite numerous advances in treatment options, advanced gastric cancer (AGC) remains a major public health issue and the leading cause of cancer-related deaths. Cisplatin is one of the most effective broad-spectrum anticancer drugs for AGC and a doublet combination regimen of either cisplatin-based or 5-fluorouracil (5FU)-based chemotherapy is generally used for treatment of patients with AGC. However, there is still no consensus on the best regimen for treating AGC. Recently, various new chemotherapeutic agents, including oral 5FU, taxanes, and irinotecan, have been identified as improving the outcomes for AGC when used as a single agent or in combination with non-platinum chemotherapy. Nonetheless, it is still unclear whether non-platinum-based chemotherapy is a viable treatment option for patients with AGC. Accordingly, this review focuses on the efficacy and tolerability of non-platinum-based chemotherapy for patients with AGC. PMID:24833869

  20. Non-platinum-based chemotherapy for treatment of advanced gastric cancer: 5-fluorouracil, taxanes, and irinotecan

    PubMed Central

    Kang, Byung Woog; Kim, Jong Gwang; Kwon, Oh-Kyoung; Chung, Ho Young; Yu, Wansik

    2014-01-01

    Despite numerous advances in treatment options, advanced gastric cancer (AGC) remains a major public health issue and the leading cause of cancer-related deaths. Cisplatin is one of the most effective broad-spectrum anticancer drugs for AGC and a doublet combination regimen of either cisplatin-based or 5-fluorouracil (5FU)-based chemotherapy is generally used for treatment of patients with AGC. However, there is still no consensus on the best regimen for treating AGC. Recently, various new chemotherapeutic agents, including oral 5FU, taxanes, and irinotecan, have been identified as improving the outcomes for AGC when used as a single agent or in combination with non-platinum chemotherapy. Nonetheless, it is still unclear whether non-platinum-based chemotherapy is a viable treatment option for patients with AGC. Accordingly, this review focuses on the efficacy and tolerability of non-platinum-based chemotherapy for patients with AGC. PMID:24833869

  1. A unique subset of epithelial ovarian cancers with platinum sensitivity and PARP inhibitor resistance.

    PubMed

    Ceccaldi, Raphael; O'Connor, Kevin W; Mouw, Kent W; Li, Adam Y; Matulonis, Ursula A; D'Andrea, Alan D; Konstantinopoulos, Panagiotis A

    2015-02-15

    Platinum and PARP inhibitor (PARPi) sensitivity commonly coexist in epithelial ovarian cancer (EOC) due to the high prevalence of alterations in the homologous recombination (HR) DNA repair pathway that confer sensitivity to both drugs. In this report, we describe a unique subset of EOC with alterations in another DNA repair pathway, the nucleotide excision repair (NER) pathway, which may exhibit a discordance in sensitivities to these drugs. Specifically, 8% of high-grade serous EOC from The Cancer Genome Atlas dataset exhibited NER alterations, including nonsynonymous or splice site mutations and homozygous deletions of NER genes. Tumors with NER alterations were associated with improved overall survival (OS) and progression-free survival (PFS), compared with patients without NER alterations or BRCA1/2 mutations. Furthermore, patients with tumors with NER alterations had similar OS and PFS as BRCA1/2-mutated patients, suggesting that NER pathway inactivation in EOC conferred enhanced platinum sensitivity, similar to BRCA1/2-mutated tumors. Moreover, two NER mutations (ERCC6-Q524* and ERCC4-A583T), identified in the two most platinum-sensitive tumors, were functionally associated with platinum sensitivity in vitro. Importantly, neither NER alteration affected HR or conferred sensitivity to PARPi or other double-strand break-inducing agents. Overall, our findings reveal a new mechanism of platinum sensitivity in EOC that, unlike defective HR, may lead to a discordance in sensitivity to platinum and PARPi, with potential implications for previously reported and ongoing PARPi trials in this disease. PMID:25634215

  2. Do platinum salts fit all triple negative breast cancers?

    PubMed

    Gerratana, L; Fanotto, V; Pelizzari, G; Agostinetto, E; Puglisi, F

    2016-07-01

    Triple-negative breast cancer (TNBC) is an aggressive disease with limited treatment options and poor prognosis once metastatic. Pre-clinical and clinical data suggest that TNBC could be more sensitive to platinum-based chemotherapy, especially among BRCA1/2-mutated patients. In recent years, several randomised trials have been conducted to evaluate platinum efficacy in both early-stage and advanced TNBC, with conflicting results especially for long-term outcomes. Experimental studies are now focusing on identifying biomarkers of response to help selecting patients who may benefit most from platinum-based therapies, including BRCA1/2 mutational status and genomic instability signatures (such as HRD-LOH or HRD-LST scores). A standard therapy for TNBC is still missing and platinum-based regimens represent an emerging therapeutic option for selected patients with a defect in the homologous recombination repair system. The identification of these patients through validated biomarker assays will be crucial to optimize the use of currently approved agents in TNBC. PMID:27343437

  3. Modified agar dilution susceptibility testing method for determining in vitro activities of antifungal agents, including azole compounds.

    PubMed Central

    Yoshida, T; Jono, K; Okonogi, K

    1997-01-01

    In vitro activities of antifungal agents, including azole compounds, against yeasts were easily determined by using RPMI-1640 agar medium and by incubating the plates in the presence of 20% CO2. The end point of inhibition was clear by this method, even in the case of azole compounds, because of the almost complete inhibition of yeast growth at high concentrations which permitted weak growth of some Candida strains by traditional methods. MICs obtained by the agar dilution method were similar to those obtained by the broth dilution method proposed by the National Committee for Clinical Laboratory Standards. PMID:9174197

  4. Exploiting developments in nanotechnology for the preferential delivery of platinum-based anti-cancer agents to tumours: targeting some of the hallmarks of cancer.

    PubMed

    Parker, James P; Ude, Ziga; Marmion, Celine J

    2016-01-01

    Platinum drugs as anti-cancer therapeutics are held in extremely high regard. Despite their success, there are drawbacks associated with their use; their dose-limiting toxicity, their limited activity against an array of common cancers and patient resistance to Pt-based therapeutic regimes. Current investigations in medicinal inorganic chemistry strive to offset these shortcomings through selective targeting of Pt drugs and/or the development of Pt drugs with new or multiple modes of action. A comprehensive overview showcasing how liposomes, nanocapsules, polymers, dendrimers, nanoparticles and nanotubes may be employed as vehicles to selectively deliver cytotoxic Pt payloads to tumour cells is provided. PMID:26567482

  5. Failure mechanism characterization of platinum alloy

    NASA Technical Reports Server (NTRS)

    Rosen, J. M.; Mcfarlen, W. T.

    1986-01-01

    This article describes procedures and results of testing performed on a platinum/10-percent rhodium, thin-wall tubular product. The purpose of the testing was to develop exemplar SEM fractographs to be used to characterize failures under various environmental conditions. Conditions evaluated for the platinum alloys included high temperature, hydrogen environment, braze metal contamination, and cyclic loading.

  6. Mineral resource of the month: platinum-group metals

    USGS Publications Warehouse

    Hilliard, Henry

    2003-01-01

    The precious metals commonly referred to as platinum-group metals (PGM) include iridium, osmium, palladium, platinum, rhodium and ruthenium. PGM are among the rarest of elements, and their market values — particularly for palladium, platinum and rhodium — are the highest of all precious metals.

  7. PLATINUM AND FUEL CELLS

    EPA Science Inventory

    Platinum requirements for fuel cell vehicles (FCVS) have been identified as a concern and possible problem with FCV market penetration. Platinum is a necessary component of the electrodes of fuel cell engines that power the vehicles. The platinum is deposited on porous electrodes...

  8. Platinum recycling in the United States in 1998

    USGS Publications Warehouse

    Hilliard, Henry E.

    2001-01-01

    In the United States, catalytic converters are the major source of secondary platinum for recycling. Other sources of platinum scrap include reforming and chemical process catalysts. The glass industry is a small but significant source of platinum scrap. In North America, it has been estimated that in 1998 more than 20,000 kilograms per year of platinum-group metals from automobile catalysts were available for recycling. In 1998, an estimated 7,690 kilograms of platinum were recycled in the United States. U.S. recycling efficiency was calculated to have been 76 percent in 1998; the recycling rate was estimated at 16 percent.

  9. PLATINUM HEXAFLUORIDE AND METHOD OF FLUORINATING PLUTONIUM CONTAINING MIXTURES THERE-WITH

    DOEpatents

    Malm, J.G.; Weinstock, B.; Claassen, H.H.

    1959-07-01

    The preparation of platinum hexafluoride and its use as a fluorinating agent in a process for separating plutonium from fission products is presented. According to the invention, platinum is reacted with fluorine gas at from 900 to 1100 deg C to form platinum hexafluoride. The platinum hexafluoride is then contacted with the plutonium containing mixture at room temperature to form plutonium hexafluoride which is more volatile than the fission products fluorides and therefore can be isolated by distillation.

  10. Cancer morbidity in British military veterans included in chemical warfare agent experiments at Porton Down: cohort study

    PubMed Central

    Linsell, L; Brooks, C; Keegan, T J; Langdon, T; Doyle, P; Maconochie, N E S; Fletcher, T; Nieuwenhuijsen, M J; Beral, V

    2009-01-01

    Objective To determine cancer morbidity in members of the armed forces who took part in tests of chemical warfare agents from 1941 to 1989. Design Historical cohort study, with cohort members followed up to December 2004. Data source Archive of UK government research facility at Porton Down, UK military personnel records, and national death and cancer records. Participants All veterans included in the cohort study of mortality, excluding those known to have died or been lost to follow-up before 1 January 1971 when the UK cancer registration system commenced: 17 013 male members of the UK armed forces who took part in tests (Porton Down veterans) and a similar group of 16 520 men who did not (non-Porton Down veterans). Main outcome measures Cancer morbidity in each group of veterans; rate ratios, with 95% confidence intervals, adjusted for age group and calendar period. Results 3457 cancers were reported in the Porton Down veterans compared with 3380 cancers in the non-Porton Down veterans. While overall cancer morbidity was the same in both groups (rate ratio 1.00, 95% confidence interval 0.95 to 1.05), Porton Down veterans had higher rates of ill defined malignant neoplasms (1.12, 1.02 to 1.22), in situ neoplasms (1.45, 1.06 to 2.00), and those of uncertain or unknown behaviour (1.32, 1.01 to 1.73). Conclusion Overall cancer morbidity in Porton Down veterans was no different from that in non-Porton Down veterans. PMID:19318700

  11. PLATINUM-GROUP METALS

    EPA Science Inventory

    The document assembles, organizes, and evaluates all pertinent information (up to April 1976) about the effects on man and his environment that result either directly or indirectly from pollution by platinum-group metals: iridium (Ir), osmium (Os), palladium (Pd), platinum (Pt), ...

  12. Platinum-containing compound platinum pyrithione is stronger and safer than cisplatin in cancer therapy.

    PubMed

    Zhao, Chong; Chen, Xin; Zang, Dan; Lan, Xiaoying; Liao, Siyan; Yang, Changshan; Zhang, Peiquan; Wu, Jinjie; Li, Xiaofen; Liu, Ningning; Liao, Yuning; Huang, Hongbiao; Shi, Xianping; Jiang, Lili; Liu, Xiuhua; He, Zhimin; Wang, Xuejun; Liu, Jinbao

    2016-09-15

    DNA is the well-known molecular target of current platinum-based anticancer drugs; consequently, their clinical use is severely restricted by their systemic toxicities and drug resistance originating from non-selective DNA damage. Various strategies have been developed to circumvent the shortcomings of platinum-based chemotherapy but the inherent problem remains unsolved. Here we report that platinum pyrithione (PtPT), a chemically well-characterized synthetic complex of platinum, inhibits proteasome function and thereby exhibits greater and more selective cytotoxicity to multiple cancer cells than cisplatin, without showing discernible DNA damage both in vitro and in vivo. Moreover, unlike the classical proteasome inhibitor bortezomib/Velcade which inhibits the proteasome via blocking the peptidase activity of 20S proteasomes, PtPT primarily deactivates 26S proteasome-associated deubiquitinases USP14 and UCHL5. Furthermore, PtPT can selectively induce cytotoxicity and proteasome inhibition in cancer cells from leukemia patients but not peripheral blood mononuclear cells from healthy humans. In nude mice, PtPT also remarkably inhibited tumor xenograft growth, without showing the adverse effects that were induced by cisplatin. Hence, we have discovered a new platinum-based anti-tumor agent PtPT which targets 26S proteasome-associated deubiquitinases rather than DNA in the cell and thereby exerts safer and more potent anti-tumor effects, identifying a highly translatable new platinum-based anti-cancer strategy. PMID:27381943

  13. Improving Platinum Efficiency:. Nanoformulations

    NASA Astrophysics Data System (ADS)

    Carmona, Rolando; Liang, Xing-Jie

    2013-09-01

    Platinum-based drugs continue being the support of therapy for many different kinds of cancer. Cancer patients often present irreversible resistance to platinum after repeated treatment in clinic. Despite of the great efforts, chemoresistance (intrinsic or acquired) already is a major limitation in the management of this disease. In this review, the last current research on cancer characteristic and cancer chemical resistance is summarized, the major and novel strategies to reverse resistance to platinum- based drugs are discussed and this article mainly emphasizes the contribution of nanotechnology and combination therapies to target sites and reduce the cancer chemoresistance.

  14. Solar abundance of platinum

    PubMed Central

    Burger, Harry; Aller, Lawrence H.

    1975-01-01

    Three lines of neutral platinum, located at λ 2997.98 Å, λ 3064.71 Å, and λ 3301.86 Å have been used to determine the solar platinum abundance by the method of spectral synthesis. On the scale, log A(H) = 12.00, the thus-derived solar platinum abundance is 1.75 ± 0.10, in fair accord with Cameron's value of log A(Pt) = 1.69 derived by Mason from carbonaceous chondrites and calculated on the assumption that log A(Si) = 7.55 in the sun. PMID:16592278

  15. New Pyrrole Derivatives with Potent Tubulin Polymerization Inhibiting Activity As Anticancer Agents Including Hedgehog-Dependent Cancer

    PubMed Central

    La Regina, Giuseppe; Bai, Ruoli; Coluccia, Antonio; Famiglini, Valeria; Pelliccia, Sveva; Passacantilli, Sara; Mazzoccoli, Carmela; Ruggieri, Vitalba; Sisinni, Lorenza; Bolognesi, Alessio; Rensen, Whilelmina Maria; Miele, Andrea; Nalli, Marianna; Alfonsi, Romina; Di Marcotullio, Lucia; Gulino, Alberto; Brancale, Andrea; Novellino, Ettore; Dondio, Giulio; Vultaggio, Stefania; Varasi, Mario; Mercurio, Ciro; Hamel, Ernest; Lavia, Patrizia; Silvestri, Romano

    2014-01-01

    We synthesized 3-aroyl-1-arylpyrrole (ARAP) derivatives as potential anticancer agents having different substituents at the pendant 1-phenyl ring. Both the 1-phenyl ring and 3-(3,4,5-trimethoxyphenyl)carbonyl moieties were mandatory to achieve potent inhibition of tubulin polymerization, binding of colchicine to tubulin, and cancer cell growth. ARAP 22 showed strong inhibition of the P-glycoprotein-overexpressing NCI-ADR-RES and Messa/Dx5MDR cell lines. Compounds 22 and 27 suppressed in vitro the Hedgehog signaling pathway, strongly reducing luciferase activity in SAG treated NIH3T3 Shh-Light II cells, and inhibited the growth of medulloblastoma D283 cells at nanomolar concentrations. ARAPs 22 and 27 represent a new potent class of tubulin polymerization and cancer cell growth inhibitors with the potential to inhibit the Hedgehog signaling pathway. PMID:25025991

  16. Exhaust system having a gold-platinum group metal catalyst

    DOEpatents

    Ragle, Christie Susan; Silver, Ronald G.; Zemskova, Svetlana Mikhailovna; Eckstein, Colleen J.

    2011-12-06

    A method of providing an exhaust treatment device is disclosed. The method includes applying a catalyst including gold and a platinum group metal to a particulate filter. The concentration of the gold and the platinum group metal is sufficient to enable oxidation of carbon monoxide and nitric oxide.

  17. Exhaust system having a gold-platinum group metal catalyst

    DOEpatents

    Ragle, Christie Susan; Silver, Ronald G.; Zemskova, Svetlana Mikhailovna; Eckstein, Colleen J.

    2012-08-07

    A method of providing an exhaust treatment device is disclosed. The method includes applying a catalyst including gold and a platinum group metal to a particulate filter. The concentration of the gold and the platinum group metal is sufficient to enable oxidation of carbon monoxide and nitric oxide.

  18. Influence of reducing agents on the cytotoxic activity of platinum(IV) complexes: induction of G2/M arrest, apoptosis and oxidative stress in A2780 and cisplatin resistant A2780cis cell lines.

    PubMed

    Pichler, Verena; Göschl, Simone; Schreiber-Brynzak, Ekaterina; Jakupec, Michael A; Galanski, Markus; Keppler, Bernhard K

    2015-07-01

    The concept of Pt(IV) prodrug design is one advanced strategy to increase the selectivity for cancer cells and to reduce systemic toxicity in comparison to established platinum-based chemotherapy. Pt(IV) complexes are thought to be activated by reduction via physiological reductants, such as ascorbic acid or glutathione. Nevertheless, only few investigations on the link between the reduction rate, which is influenced by the reductant, and the ligand sphere of the Pt(IV) metal centre have been performed so far. Herein, we investigated a set of Pt(IV) compounds with varying rates of reduction with respect to their cytotoxicity and drug accumulation in A2780 and A2780cis ovarian cancer cell lines, their influence on the cell cycle, efficiency of triggering apoptosis, and ability to interfere with plasmid DNA (pUC19). The effects caused by Pt(IV) compounds were compared without or with extracellularly added ascorbic acid and glutathione (or its precursor N-acetylcysteine) to gain understanding of the impact of increased levels of the reductant on the activity of such complexes. Our results demonstrate that reduction is required prior to plasmid interaction. Furthermore, the rate of reduction is crucial for the efficiency of this set of Pt(IV) compounds. The substances that are reduced least likely showed similar performances, whereas the fastest reducing substance was negatively affected by an increased extracellular level of reducing agents, with reduced cytotoxicity and lower efficiency in inducing apoptosis and G2/M arrest. These results confirm the connection between reduction and activity, and prove the strong impact of the reduction site on the activity of Pt(IV) complexes. PMID:26073554

  19. Dichloroacetate should be considered with platinum-based chemotherapy in hypoxic tumors rather than as a single agent in advanced non-small cell lung cancer

    PubMed Central

    Garon, Edward B.; Christofk, Heather R.; Hosmer, Wylie; Britten, Carolyn D; Bahng, Agnes; Crabtree, Matthew J; Hong, Candice Sun; Kamranpour, Naeimeh; Pitts, Sharon; Kabbinavar, Fairooz; Patel, Cecil; von Euw, Erika; Black, Alexander; Michelakis, Evangelos D.; Dubinett, Steven M.; Slamon, Dennis J.

    2014-01-01

    Objectives Dichloroacetate (DCA) is a highly bioavailable small molecule that inhibits pyruvate dehydrogenase kinase, promoting glucose oxidation and reversing the glycolytic phenotype in preclinical cancer studies. We designed this open label phase II trial to determine the response rate, safety, and tolerability of oral DCA in patients with metastatic breast cancer and advanced stage NSCLC. Materials and Methods This trial was conducted with DCA 6.25 mg/kg orally twice daily in previously treated stage IIIB/IV non-small cell lung cancer (NSCLC) or stage IV breast cancer. Growth inhibition by DCA was also evaluated in a panel of 54 NSCLC cell lines with and without cytotoxic chemotherapeutics (cisplatin and docetaxel) in normoxic and hypoxic conditions. Results and Conclusions Under normoxic conditions in vitro, single agent IC50 was > 2 mM for all evaluated cell lines. Synergy with cisplatin was seen in some cell lines under hypoxic conditions. In the clinical trial, after seven patients were enrolled, the study was closed based on safety concerns. The only breast cancer patient had stable disease after 8 weeks, quickly followed by progression in the brain. Two patients withdrew consent within a week of enrollment. Two patients had disease progression prior to the first scheduled scans. Within one week of initiating DCA, one patient died suddenly of unknown cause, and one experienced a fatal pulmonary embolism. We conclude that patients with previously treated advanced NSCLC did not benefit from oral DCA. In the absence of a larger controlled trial, firm conclusions regarding the association between these adverse events and DCA are unclear. Further development of DCA should be in patients with longer life expectancy, in whom sustained therapeutic levels can be achieved, and potentially in combination with cisplatin. PMID:24442098

  20. Controlled synthesis of porous platinum nanostructures for catalytic applications.

    PubMed

    Cao, Yanqin; Zhang, Junwei; Yang, Yong; Huang, Zhengren; Long, Nguyen Viet; Nogami, Masayuki

    2014-02-01

    Porous platinum, that has outstanding catalytic and electrical properties and superior resistant characteristics to corrosion, has been widely applied in chemical, petrochemical, pharmaceutical, electronic, and automotive industries. As the catalytic activity and selectivity depend on the size, shape and structure of nanomaterials, the strategies for controlling these factors of platinum nanomaterials to get excellent catalytic properties are discussed. Here, recent advances in the design and preparation of various porous platinum nanostructures are reviewed, including wet-chemical synthesis, electro-deposition, galvanic replacement reaction and de-alloying technology. The applications of various platinum nanostructures are also discussed, especially in fuel cells. PMID:24749422

  1. 21 CFR 700.13 - Use of mercury compounds in cosmetics including use as skinbleaching agents in cosmetic...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 7 2010-04-01 2010-04-01 false Use of mercury compounds in cosmetics including...) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.13 Use of mercury compounds in cosmetics..., mercury compounds have also been widely used as preservatives in cosmetics such as hand and body...

  2. 21 CFR 700.13 - Use of mercury compounds in cosmetics including use as skinbleaching agents in cosmetic...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 7 2013-04-01 2013-04-01 false Use of mercury compounds in cosmetics including...) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.13 Use of mercury compounds in cosmetics..., mercury compounds have also been widely used as preservatives in cosmetics such as hand and body...

  3. 21 CFR 700.13 - Use of mercury compounds in cosmetics including use as skinbleaching agents in cosmetic...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 7 2011-04-01 2010-04-01 true Use of mercury compounds in cosmetics including use... GENERAL Requirements for Specific Cosmetic Products § 700.13 Use of mercury compounds in cosmetics..., mercury compounds have also been widely used as preservatives in cosmetics such as hand and body...

  4. 21 CFR 700.13 - Use of mercury compounds in cosmetics including use as skinbleaching agents in cosmetic...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 7 2014-04-01 2014-04-01 false Use of mercury compounds in cosmetics including...) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.13 Use of mercury compounds in cosmetics..., mercury compounds have also been widely used as preservatives in cosmetics such as hand and body...

  5. 21 CFR 700.13 - Use of mercury compounds in cosmetics including use as skinbleaching agents in cosmetic...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 7 2012-04-01 2012-04-01 false Use of mercury compounds in cosmetics including...) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.13 Use of mercury compounds in cosmetics..., mercury compounds have also been widely used as preservatives in cosmetics such as hand and body...

  6. Platinum particle size and support effects in NO(x) mediated carbon oxidation over platinum catalysts.

    PubMed

    Villani, Kenneth; Vermandel, Walter; Smets, Koen; Liang, Duoduo; van Tendeloo, Gustaaf; Martens, Johan A

    2006-04-15

    Platinum metal was dispersed on microporous, mesoporous, and nonporous support materials including the zeolites Na-Y, Ba-Y, Ferrierite, ZSM-22, ETS-10, and AIPO-11, alumina, and titania. The oxidation of carbon black loosely mixed with catalyst powder was monitored gravimetrically in a gas stream containing nitric oxide, oxygen, and water. The carbon oxidation activity of the catalysts was found to be uniquely related to the Pt dispersion and little influenced by support type. The optimum dispersion is around 3-4% corresponding to relatively large Pt particle sizes of 20-40 nm. The carbon oxidation activity reflects the NO oxidation activity of the platinum catalyst, which reaches an optimum in the 20-40 nm Pt particle size range. The lowest carbon oxidation temperatures were achieved with platinum loaded ZSM-22 and AIPO-11 zeolite crystallites bearing platinum of optimum dispersion on their external surfaces. PMID:16683615

  7. Rapid biological synthesis of platinum nanoparticles using Ocimum sanctum for water electrolysis applications.

    PubMed

    Soundarrajan, C; Sankari, A; Dhandapani, P; Maruthamuthu, S; Ravichandran, S; Sozhan, G; Palaniswamy, N

    2012-06-01

    The leaf extract of Ocimum sanctum was used as a reducing agent for the synthesis of platinum nanoparticles from an aqueous chloroplatinic acid (H(2)PtCl(6)·6H(2)O). A greater conversion of platinum ions to nanoparticles was achieved by employing a tulsi leaf broth with a reaction temperature of 100 °C. Energy-dispersive absorption X-ray spectroscopy confirmed the platinum particles as major constituent in the reduction process. It is evident from scanning electron microscopy that the reduced platinum particles were found as aggregates with irregular shape. Fourier-transform infrared spectroscopy revealed that the compounds such as ascorbic acid, gallic acid, terpenoids, certain proteins and amino acids act as reducing agents for platinum ions reduction. X-ray diffraction spectroscopy suggested the associated forms of platinum with other molecules and the average particle size of platinum nanoparticle was 23 nm, calculated using Scherer equation. The reduced platinum showed similar hydrogen evolution potential and catalytic activity like pure platinum using linear scan voltammetry. This environmentally friendly method of biological platinum nanoparticles production increases the rates of synthesis faster which can potentially be used in water electrolysis applications. PMID:22167464

  8. Growth of platinum nanocrystals

    SciTech Connect

    2009-01-01

    Movie showing the growth of platinum nanocrystals in a liquid cell observed in situ using the JEOL 3010 TEM at the National Center for Electron Microscopy. This is the first ever-real time movie showing nucleation and growth by monomer attachment or by smaller nanocrystals coalescing to form larger nanocrystals. All the nanocrystals end up being roughly the same shape and size. http://newscenter.lbl.gov/feature-stories/2009/08/04/growth-spurts/

  9. Membrane fuel cell cathode catalysts based on titanium oxide supported platinum nanoparticles.

    PubMed

    Gebauer, Christian; Jusys, Zenonas; Wassner, Maximilian; Hüsing, Nicola; Behm, R Jürgen

    2014-07-21

    The potential of platinum catalysts supported on pure, nitrogen-, or carbon-doped titania for application in the oxygen reduction reaction (ORR), as a cathode catalyst in polymer electrolyte membrane fuel cells, is investigated. The oxide supports are synthesized by using a sol-gel route. Modification with nitrogen and carbon doping is achieved by thermal decomposition of urea and the structure-directing agent P123. Platinum nanoparticles are prepared by reduction of a Pt(IV) salt in ethylene glycol and subsequently immobilized on different support materials. Structural and electronic properties of the support materials and the resulting catalysts are characterized by various methods, including X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. These results and electrochemical characterization of the support materials and platinum nanoparticle catalysts indicate distinct support effects in the catalysts. The electrocatalytic performance of these catalysts in the ORR, as determined in rotating ring disc electrode measurements, is promising. Also here, distinct support effects can be identified. Correlations with the structural/electronic and the electrochemical properties are discussed, as well as the role of metal-support interactions. PMID:24850442

  10. Evolving concepts in the management of drug resistant ovarian cancer: dose dense chemotherapy and the reversal of clinical platinum resistance.

    PubMed

    Pinato, David J; Graham, Janet; Gabra, Hani; Sharma, Rohini

    2013-04-01

    Despite the initially high response rate to standard front-line debulking surgery followed by platinum-based chemotherapy, the relapse rate in ovarian cancer is high and many patients will recur within 6 months of completing platinum based treatment. These patients may still require further chemotherapy despite being considered "platinum resistant". In this setting, response rates to conventionally scheduled second line platinum and non-platinum agents is low, ranging between 5% and 15%. There is an emerging body of evidence that in this scenario, chemotherapeutic activity can be enhanced using unconventionally scheduled "dose-dense" platinum and non-platinum based regimens with improved response rates of up to 65%. Randomised studies to evaluate the impact of this approach on survival in recurrent, platinum resistant disease are urgently required to confirm the promising phase II findings if there is to be a change in the standard of care of patients with platinum resistant disease. In this review we discuss the evolving strategies to overcome resistance in patients with platinum resistant ovarian cancer with a particular focus on alterations in dose schedule as a means of reversing platinum resistance. PMID:22595680

  11. Screening of antimicrobial agents for in vitro radiation protection and mitigation capacity, including those used in supportive care regimens for bone marrow transplant recipients.

    PubMed

    Epperly, Michael W; Franicola, Darcy; Shields, Donna; Rwigema, Jean-Claude; Stone, Brandon; Zhang, Xichen; McBride, William; Georges, George; Wipf, Peter; Greenberger, Joel S

    2010-01-01

    Antibiotic and antifungal agents used in supportive care regimens for bone marrow transplantation recipients contribute to a significant dose-modifying effect of otherwise lethal total body irradiation. To determine whether drugs used in supportive care and other commonly used antibiotics such as tetracycline function as radiation protectors or damage mitigators in vitro, 13 drugs were tested for radiation protection and radiation damage mitigation of 32D cl 3 hematopoietic progenitor cells in clonagenic survival curves in vitro. Antibiotic/Antifungal agents including cilastatin, amikacin, ceftazidine, vancomycin, tetracycline, doxycycline, ciprofloxacin, metronidazole, methacycline, minocycline, meclocycline, oxytetracycline and rolitetracycline were added in 1, 10, or 100 micromolar concentrations to murine interleukin-3-dependent hematopoietic progenitor cell line 32D cl 3 cells either before or after irradiation of 0 to 8 Gy. Control irradiated 32D cl 3 cells showed radiosensitivity comparable to freshly explanted mouse marrow hematopoietic progenitor cells (D(0) 1.1+/-0.1 Gy, N 1.5+/-0.4). Positive control GS-nitroxide JP4-039 (known radiation mitigator) treated 32D cl 3 cells were radioresistant (D(0) 1.2+/-0.1, N 5.8+/-2.4 (p=0.009)). Of the 13 drugs tested, tetracycline was found to be a significant radiation mitigator (D(0) 0.9+/-0.1, N 13.9+/-0.4 (p=0.0027)). Thus, the radiation dose-modifying effect of some antibiotics, but not those currently used in the supportive care (antibiotic/antifungal regimens) for marrow transplant patients, may act as radiation damage mitigators for hematopoietic cells as well as decreasing the growth and inflammatory response to microbial pathogens. PMID:20133970

  12. Mineral resource of the month: platinum group metals

    USGS Publications Warehouse

    Loferski, Patricia J.

    2010-01-01

    The article focuses on platinum group metals (PGMs) and their properties. According to the author, PGMs, which include iridium, osmium, palladium, platinum, rhodium, and ruthenium, are among the rarest mineral commodities in the Earth's crust. PGMs are primarily used as catalytic converters that clean harmful exhaust from vehicle engines. They are also used in the chemical industry as catalysts in the production of nitric acid and in the petroleum refining industry.

  13. Current state of evidence on 'off-label' therapeutic options for systemic lupus erythematosus, including biological immunosuppressive agents, in Germany, Austria and Switzerland--a consensus report.

    PubMed

    Aringer, M; Burkhardt, H; Burmester, G R; Fischer-Betz, R; Fleck, M; Graninger, W; Hiepe, F; Jacobi, A M; Kötter, I; Lakomek, H J; Lorenz, H M; Manger, B; Schett, G; Schmidt, R E; Schneider, M; Schulze-Koops, H; Smolen, J S; Specker, C; Stoll, T; Strangfeld, A; Tony, H P; Villiger, P M; Voll, R; Witte, T; Dörner, T

    2012-04-01

    Systemic lupus erythematosus (SLE) can be a severe and potentially life-threatening disease that often represents a therapeutic challenge because of its heterogeneous organ manifestations. Only glucocorticoids, chloroquine and hydroxychloroquine, azathioprine, cyclophosphamide and very recently belimumab have been approved for SLE therapy in Germany, Austria and Switzerland. Dependence on glucocorticoids and resistance to the approved therapeutic agents, as well as substantial toxicity, are frequent. Therefore, treatment considerations will include 'off-label' use of medication approved for other indications. In this consensus approach, an effort has been undertaken to delineate the limits of the current evidence on therapeutic options for SLE organ disease, and to agree on common practice. This has been based on the best available evidence obtained by a rigorous literature review and the authors' own experience with available drugs derived under very similar health care conditions. Preparation of this consensus document included an initial meeting to agree upon the core agenda, a systematic literature review with subsequent formulation of a consensus and determination of the evidence level followed by collecting the level of agreement from the panel members. In addition to overarching principles, the panel have focused on the treatment of major SLE organ manifestations (lupus nephritis, arthritis, lung disease, neuropsychiatric and haematological manifestations, antiphospholipid syndrome and serositis). This consensus report is intended to support clinicians involved in the care of patients with difficult courses of SLE not responding to standard therapies by providing up-to-date information on the best available evidence. PMID:22072024

  14. Development of Platinum(iv) Complexes as Anticancer Prodrugs: the Story so Far

    NASA Astrophysics Data System (ADS)

    Wong, Daniel Yuan Qiang; Ang, Wee Han

    2012-06-01

    The serendipitous discovery of the antitumor properties of cisplatin by Barnett Rosenberg some forty years ago brought about a paradigm shift in the field of medicinal chemistry and challenged conventional thinking regarding the role of potentially toxic heavy metals in drugs. Platinum(II)-based anticancer drugs have since become some of the most effective and widely-used drugs in a clinician's arsenal and have saved countless lives. However, they are limited by high toxicity, severe side-effects and the incidence of drug resistance. In recent years, attention has shifted to stable platinum(IV) complexes as anticancer prodrugs. By exploiting the unique chemical and structural attributes of their scaffolds, these platinum(IV) prodrugs offer new strategies of targeting and killing cancer cells. This review summarizes the development of anticancer platinum(IV) prodrugs to date and some of the exciting strategies that utilise the platinum(IV) construct as targeted chemotherapeutic agents against cancer.

  15. Platinum-based chemotherapy in triple-negative breast cancer: a systematic review and meta-analysis of randomized-controlled trials.

    PubMed

    Guan, Xiuwen; Ma, Fei; Fan, Ying; Zhu, Wenjie; Hong, Ruoxi; Xu, Binghe

    2015-09-01

    The aim of this study was to evaluate the benefits of the addition of platinum agents for the treatment of patients with triple-negative breast cancer on the basis of randomized-controlled trials (RCTs). A fully recursive literature search was performed in the Cochrane Controlled Trials Register Databases, Medline, EMBASE, and Chinese Biomedical Literature Database in any language. RCTs were considered for inclusion. Eight randomized-controlled trials totaling 1142 patients were included. The objective response rate was reported in six RCTs, which were divided into two subgroups: palliative chemotherapy for a metastatic setting and neoadjuvant chemotherapy. Using the fixed-effects model, the difference between the platinum-based group and the non-platinum-based group was found to be statistically significant in the overall study [relative risk (RR)=1.36, P<0.00001], the subgroup of palliative chemotherapy (RR=2.42, P<0.00001), and the subgroup of neoadjuvant (RR=1.15, P=0.01). Pathological complete response rates were based on five studies, and the results between the platinum-based group and the non-platinum-based group also reached statistical significance both in the fixed-effects model (RR=1.43, P<0.0001) and in the random-effects model (RR=1.47, P=0.01). The results seemed to yield a better response rate and pathological complete response rate for platinum-based therapy in triple-negative breast cancer. However, because of the heterogeneous nature of primary trial outcomes, caution should be exercised in coming to this conclusion and further research is necessary to support these findings. PMID:26086398

  16. Silicone breast implants and platinum.

    PubMed

    Wixtrom, Roger N

    2007-12-01

    Platinum, in a specific form, is used as a catalyst in the cross-linking reactions of the silicone gel and elastomer in breast implants. After manufacture, it remains in the devices at low-parts-per-million levels. Potential concerns have been raised as to whether this platinum might diffuse from silicone breast implants into the body and result in adverse health effects. The weight of evidence indicates that the platinum present is in its most biocompatible (zero valence) form, and the very minute levels (<0.1 percent) that might diffuse from the implants do not represent a significant health risk to patients. PMID:18090821

  17. Influence of Dose on Particle Size and Optical Properties of Colloidal Platinum Nanoparticles

    PubMed Central

    Gharibshahi, Elham; Saion, Elias

    2012-01-01

    Attempts to produce colloidal platinum nanoparticles by using steady absorption spectra with various chemical-based reduction methods often resulted in the fast disappearance of the absorption maxima leaving reduced platinum nanoparticles with little information on their optical properties. We synthesized colloidal platinum nanoparticles in an aqueous solution of polyvinyl pyrrolidone by gamma radiolytic reduction method, which produced steady absorption spectra of fully reduced and highly pure platinum nanoparticles free from by-product impurities or reducing agent contamination. The average particle size was found to be in the range of 3.4–5.3 nm and decreased with increasing dose due to the domination of nucleation over ion association in the formation of metal nanoparticles by the gamma radiolytic reduction method. The platinum nanoparticles exhibit optical absorption spectra with two absorption peaks centered at about 216 and 264 nm and the peaks blue shifted to lower wavelengths with decreasing particle size. The absorption spectra of platinum nanoparticles were also calculated using quantum mechanical treatment and coincidently a good agreement was obtained between the calculated and measured absorption peaks at various particle sizes. This indicates that the 216 and 264-nm absorption peaks of platinum nanoparticles conceivably originated from the intra-band transitions of conduction electrons of (n = 5, l = 2) and (n = 6, l = 0) energy states respectively to higher energy states. The absorption energies, i.e., conduction band energies of platinum nanoparticles derived from the absorption peaks increased with increasing dose and decreased with increasing particle size. PMID:23203091

  18. Near-UV phosphorescent emitters: N-heterocyclic platinum(ii) tetracarbene complexes.

    PubMed

    Unger, Yvonne; Zeller, Alexander; Taige, Maria A; Strassner, Thomas

    2009-06-28

    Although examples of nickel(ii), palladium(ii) and platinum(ii) N-heterocyclic tetracarbene complexes are known in the literature, particularly platinum(ii) tetracarbene complexes are rare. We developed a new synthetic route via biscarbene acetate complexes, which make homoleptic as well as heteroleptic platinum(ii) tetracarbene complexes accessible. The reported photoluminescence data show that these complexes have good quantum yields and photostability and are a promising class of emitters for PhOLEDs. Characterization of the compounds includes a solid-state structure of the homoleptic complex bis(1,1'-diisopropyl-3,3'-methylenediimidazoline-2,2'-diylidene)platinum(ii) dibromide. PMID:19513490

  19. Biological Agents

    MedlinePlus

    ... to Z Index Contact Us FAQs What's New Biological Agents This page requires that javascript be enabled ... and Health Topics A-Z Index What's New Biological agents include bacteria, viruses, fungi, other microorganisms and ...

  20. A phase I multicenter study of antroquinonol in patients with metastatic non-small-cell lung cancer who have received at least two prior systemic treatment regimens, including one platinum-based chemotherapy regimen

    PubMed Central

    LEE, YU-CHIN; HO, CHING-LIANG; KAO, WOEI-YAU; CHEN, YUH-MIN

    2015-01-01

    Antroquinonol is isolated from Antrodia camphorata, a camphor tree mushroom, and is a valuable traditional Chinese herbal medicine that exhibits pharmacological activities against several diseases, including cancer. This first-in-human phase I study of antroquinonol included patients with metastatic non-small-cell lung cancer who had received at least two prior systemic treatment regimens. An open-label, dose escalation, pharmacokinetic (PK) study was conducted to determine the maximum tolerable dose (MTD), dose-limiting toxicities (DLTs), and safety/tolerability and preliminary efficacy profiles of antroquinonol. The patients received escalating doses of once-daily antroquinonol in 4-week cycles (up to 3 cycles). The escalated doses were 50–600 mg. PKs were evaluated on day 1 and 28 of cycle 1. Between January, 2011 and October, 2012, 13 patients with metastatic adenocarcinoma were enrolled. No DLTs occurred in any patient at any dose level. Tmax was observed between 1.00 and 3.70 h under single-dose conditions, and at 1.92–4.05 h under multiple-dose conditions. The mean elimination half-life ranged between 1.30 and 4.33 h, independent of the treatment dose. Antroquinonol at all dose levels had a mild toxicity profile, with no reported treatment-related mortality. The most common treatment-related adverse events were diarrhea, vomiting and nausea. The best tumor response was stable disease in 3 patients. In conclusion, antroquinonol at all dose levels, administered daily for 4 weeks, was generally safe and well tolerated, without DLTs. The recommended dose level for a phase II study is ≥600 mg daily. PMID:26807250

  1. Platinum availability for future automotive technologies.

    PubMed

    Alonso, Elisa; Field, Frank R; Kirchain, Randolph E

    2012-12-01

    Platinum is an excellent catalyst, can be used at high temperatures, and is stable in many aggressive chemical environments. Consequently, platinum is used in many current industrial applications, notably automotive catalytic converters, and prospective vehicle fuel cells are expected to rely upon it. Between 2005 and 2010, the automotive industry used approximately 40% of mined platinum. Future automotive industry growth and automotive sales shifts toward new technologies could significantly alter platinum demand. The potential risks for decreased platinum availability are evaluated, using an analysis of platinum market characteristics that describes platinum's geophysical constraints, institutional efficiency, and dynamic responsiveness. Results show that platinum demand for an automotive fleet that meets 450 ppm greenhouse gas stabilization goals would require within 10% of historical growth rates of platinum supply before 2025. However, such a fleet, due largely to sales growth in fuel cell vehicles, will more strongly constrain platinum supply in the 2050 time period. While current platinum reserves are sufficient to satisfy this increased demand, decreasing platinum ore grade and continued concentration of platinum supply in a single geographic area are availability risk factors to platinum end-users. PMID:23088692

  2. Comparison of inhibition kinetics of several organophosphates, including some nerve agent surrogates, using human erythrocyte and rat and mouse brain acetylcholinesterase.

    PubMed

    Coban, Alper; Carr, Russell L; Chambers, Howard W; Willeford, Kenneth O; Chambers, Janice E

    2016-04-25

    Because testing of nerve agents is limited to only authorized facilities, our laboratory developed several surrogates that resemble nerve agents because they phosphylate the acetylcholinesterase (AChE) with the same moiety as the actual nerve agents. The inhibition kinetic parameters were determined for AChE by surrogates of cyclosarin (NCMP), sarin (NIMP, PIMP and TIMP) and VX (NEMP and TEMP) and other organophosphorus compounds derived from insecticides. All compounds were tested with rat brain and a subset was tested with mouse brain and purified human erythrocyte AChE. Within the compounds tested on all AChE sources, chlorpyrifos-oxon had the highest molecular rate constant followed by NCMP and NEMP. This was followed by NIMP then paraoxon and DFP with rat and mouse brain AChE but DFP was a more potent inhibitor than NIMP and paraoxon with human AChE. With the additional compounds tested only in rat brain, TEMP was slightly less potent than NEMP but more potent than PIMP which was more potent than NIMP. Methyl paraoxon was slightly less potent than paraoxon but more potent than TIMP which was more potent than DFP. Overall, this study validates that the pattern of inhibitory potencies of our surrogates is comparable to the pattern of inhibitory potencies of actual nerve agents (i.e., cyclosarin>VX>sarin), and that these are more potent than insecticidal organophosphates. PMID:26965078

  3. Platinum in Earth surface environments

    NASA Astrophysics Data System (ADS)

    Reith, F.; Campbell, S. G.; Ball, A. S.; Pring, A.; Southam, G.

    2014-04-01

    Platinum (Pt) is a rare precious metal that is a strategic commodity for industries in many countries. The demand for Pt has more than doubled in the last 30 years due to its role in the catalytic conversion of CO, hydrocarbons and NOx in modern automobiles. To explore for new Pt deposits, process ores and deal with ecotoxicological effects of Pt mining and usage, the fundamental processes and pathways of Pt dispersion and re-concentration in surface environments need to be understood. Hence, the aim of this review is to develop a synergistic model for the cycling of Pt in Earth surface environments. This is achieved by integrating the geological/(biogeo)chemical literature, which focuses on naturally occurring Pt mobility around ore deposits, with the environmental/ecotoxicological literature dealing with anthropogenic Pt dispersion. In Pt deposits, Pt occurs as sulfide-, telluride- and arsenide, native metal and alloyed to other PGEs and iron (Fe). Increased mining and utilization of Pt combined with the burning of fossil fuels have led to the dispersion of Pt-containing nano- and micro-particles. Hence, soils and sediments in industrialized areas, urban environments and along major roads are now commonly Pt enriched. Platinum minerals, nuggets and anthropogenic particles are transformed by physical and (bio)geochemical processes. Complexation of Pt ions with chloride, thiosulfate, ammonium, cyanide, low- and high molecular weight organic acids (LMWOAs and HMWOAs) and siderophores can facilitate Pt mobilization. Iron-oxides, clays, organic matter and (micro)biota are known to sequester Pt-complexes and -particles. Microbes and plants are capable of bioaccumulating and reductively precipitating mobile Pt complexes. Bioaccumulation can lead to toxic effects on plants and animals, including humans. (Bio)mineralization in organic matter-rich sediments can lead to the formation of secondary Pt particles and -grains. Ultimately, Pt is enriched in oceanic sediments

  4. Smoking and occupational allergy in workers in a platinum refinery.

    PubMed Central

    Venables, K. M.; Dally, M. B.; Nunn, A. J.; Stevens, J. F.; Stephens, R.; Farrer, N.; Hunter, J. V.; Stewart, M.; Hughes, E. G.; Newman Taylor, A. J.

    1989-01-01

    OBJECTIVE--To test the hypothesis that smoking increases the risk of sensitisation by occupational allergens. DESIGN--Historical prospective cohort study. SETTING--Platinum refinery. SUBJECTS--91 Workers (86 men) who started work between 1 January 1973 and 31 December 1974 and whose smoking habit and atopic state (on skin prick testing with common allergens) had been noted at joining. MAIN OUTCOME MEASURES--Results of skin prick tests with platinum salts carried out routinely every three to six months and records of any respiratory symptoms noted by the refinery's occupational health service. Follow up was until 1980 or until leaving refinery work, whichever was earlier. RESULTS--57 Workers smoked and 29 were atopic; 22 developed a positive result on skin testing with platinum salts and 49 developed symptoms, including all 22 whose skin test result was positive. Smoking was the only significant predictor of a positive result on skin testing with platinum salts and its effect was greater than that of atopy; the estimated relative risks (95% confidence interval) when both were included in the regression model were: smokers versus non-smokers 5.05 (1.68 to 15.2) and atopic versus non-atopic 2.29 (0.88 to 5.99). Number of cigarettes smoked per day was the only significant predictor of respiratory symptoms. CONCLUSION--Smokers are at increased risk of sensitisation by platinum salts. PMID:2508944

  5. Role of copper transporters in platinum resistance

    PubMed Central

    Kilari, Deepak; Guancial, Elizabeth; Kim, Eric S

    2016-01-01

    Platinum (Pt)-based antitumor agents are effective in the treatment of many solid malignancies. However, their efficacy is limited by toxicity and drug resistance. Reduced intracellular Pt accumulation has been consistently shown to correlate with resistance in tumors. Proteins involved in copper homeostasis have been identified as Pt transporters. In particular, copper transporter receptor 1 (CTR1), the major copper influx transporter, has been shown to play a significant role in Pt resistance. Clinical studies demonstrated that expression of CTR1 correlated with intratumoral Pt concentration and outcomes following Pt-based therapy. Other CTRs such as CTR2, ATP7A and ATP7B, may also play a role in Pt resistance. Recent clinical studies attempting to modulate CTR1 to overcome Pt resistance may provide novel strategies. This review discusses the role of CTR1 as a potential predictive biomarker of Pt sensitivity and a therapeutic target for overcoming Pt resistance. PMID:26862494

  6. Chitosan sorbents for platinum sorption from dilute solutions

    SciTech Connect

    Guibal, E.; Larkin, A.; Vincent, T.; Tobin, J.M.

    1999-10-01

    Chitosan has proved efficient at removing platinum in dilute effluents. The maximum uptake capacity reaches 300 mg/g (almost 1.5 mmol/g). The optimum pH for sorption is pH 2. A glutaraldehyde cross-linking pretreatment is necessary to stabilize the biopolymer in acidic solutions. Sorption isotherms have been studied as a function of pH, sorbent particle size, and the cross-linking ratio. Surprisingly, the extent of the cross-linking (determined by the concentration of the cross-linking agent in the treatment bath) has no significant influence on uptake capacity. Competitor anions such as chloride or nitrate induce a large decrease in the sorption efficiency. Sorption kinetics show also that uptake rate is not significantly changed by increasing either the cross-linking ratio or the particle size of the sorbent. Mass transfer rates are significantly affected by the initial platinum concentration and by the conditioning of the biopolymer. Gel-bead conditioning appears to reduce the sorption rate. While for molybdate and vanadate ions, mass transfer was governed by intraparticle mass transfer, for platinum, both external and intraparticle diffusion control the uptake rate. In contrast with the former ions, platinum does not form polynuclear hydrolyzed species, which are responsible for steric hindrance of diffusion into the polymer network.

  7. Predicting Ovarian Cancer Patients' Clinical Response to Platinum-Based Chemotherapy by Their Tumor Proteomic Signatures.

    PubMed

    Yu, Kun-Hsing; Levine, Douglas A; Zhang, Hui; Chan, Daniel W; Zhang, Zhen; Snyder, Michael

    2016-08-01

    Ovarian cancer is the deadliest gynecologic malignancy in the United States with most patients diagnosed in the advanced stage of the disease. Platinum-based antineoplastic therapeutics is indispensable to treating advanced ovarian serous carcinoma. However, patients have heterogeneous responses to platinum drugs, and it is difficult to predict these interindividual differences before administering medication. In this study, we investigated the tumor proteomic profiles and clinical characteristics of 130 ovarian serous carcinoma patients analyzed by the Clinical Proteomic Tumor Analysis Consortium (CPTAC), predicted the platinum drug response using supervised machine learning methods, and evaluated our prediction models through leave-one-out cross-validation. Our data-driven feature selection approach indicated that tumor proteomics profiles contain information for predicting binarized platinum response (P < 0.0001). We further built a least absolute shrinkage and selection operator (LASSO)-Cox proportional hazards model that stratified patients into early relapse and late relapse groups (P = 0.00013). The top proteomic features indicative of platinum response were involved in ATP synthesis pathways and Ran GTPase binding. Overall, we demonstrated that proteomic profiles of ovarian serous carcinoma patients predicted platinum drug responses as well as provided insights into the biological processes influencing the efficacy of platinum-based therapeutics. Our analytical approach is also extensible to predicting response to other antineoplastic agents or treatment modalities for both ovarian and other cancers. PMID:27312948

  8. Can the response to a platinum-based therapy be predicted by the DNA repair status in non-small cell lung cancer?

    PubMed

    Macerelli, Marianna; Ganzinelli, Monica; Gouedard, Cedric; Broggini, Massimo; Garassino, Marina Chiara; Linardou, Helena; Damia, Giovanna; Wiesmüller, Lisa

    2016-07-01

    Preclinical evidence has been accumulating on the impact of the DNA repair status on the sensitivity/resistance to anticancer agents in different tumor types, including lung cancer. The possibility to predict the response to therapy, and specifically to platinum agents, based on tumor specific DNA repair functionality would enable to tailor its use only in those patients with maximum chances to respond, avoiding the burden of toxicity in those ones with lesser chances. We here reviewed the clinical evidence on the prognostic role of DNA repair markers and/or functional assays in predicting the response to a platinum-based chemotherapy in lung cancer patients. Consequently, we focused on those proteins involved in pathways repairing platinum induced DNA inter-strand and intra-strand crosslinks. Most promising clinical trials targeting the nucleotide repair protein ERCC1 in non-small cell lung cancer later on suffered from serious drawbacks. Nevertheless, these results spurred a variety of preclinical studies on a multitude of alternative DNA repair markers. However so far, no one of the analyzed DNA repair markers can be considered a reliable and mature biomarker for selecting patients. We discuss the reasons for such failure which discloses novel strategies for the future. PMID:27262017

  9. Development of anticancer agents: wizardry with osmium.

    PubMed

    Hanif, Muhammad; Babak, Maria V; Hartinger, Christian G

    2014-10-01

    Platinum compounds are one of the pillars of modern cancer chemotherapy. The apparent disadvantages of existing chemotherapeutics have led to the development of novel anticancer agents with alternative modes of action. Many complexes of the heavy metal osmium (Os) are potent growth inhibitors of human cancer cells and are active in vivo, often superior or comparable to cisplatin, as the benchmark metal-based anticancer agent, or clinically tested ruthenium (Ru) drug candidates. Depending on the choice of ligand system, osmium compounds exhibit diverse modes of action, including redox activation, DNA targeting or inhibition of protein kinases. In this review, we highlight recent advances in the development of osmium anticancer drug candidates and discuss their cellular mechanisms of action. PMID:24955838

  10. Preparation of low-sulfur platinum and platinum aluminide layers in thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Spitsberg, Irene T. (Inventor); Walston, William S. (Inventor); Schaeffer, Jon C. (Inventor)

    2003-01-01

    A method for preparing a coated nickel-base superalloy article reduces the sulfur content of the surface region of the metallic coating layers to low levels, thereby improving the adhesion of the coating layers to the article. The method includes depositing a first layer of platinum overlying the surface of a substrate, depositing a second layer of aluminum over the platinum, and final desulfurizing the article by heating the article to elevated temperature, preferably in hydrogen, and removing a small amount of material from the surface that was exposed during the step of heating. A ceramic layer may be deposited over the desulfurized article. The article may also be similarly desulfurized at other points in the fabrication procedure.

  11. [Platinum compounds in cancer therapy--past, present, and future].

    PubMed

    Akaza, H; Saijo, N; Aiba, K; Isonishi, S; Ohashi, Y; Kawai, K; Konishi, T; Saeki, T; Sone, S; Tsukagoshi, S; Tsuruo, T; Noguchi, S; Miki, T; Mikami, O; Smith, M; Hoctin-Boes, G; Stribling, D

    2001-05-01

    Platinum cytotoxics play an important role globally in the management of solid tumours. Cisplatin sets the standard for efficacy in both regions with careful administration to reduce nephrotoxicity. Carboplatin is associated with neurotoxicity, but has become the leading product in the US due largely to the easier to manage toxicity profile. Both agents have been widely used in both registered and non registered indications and are frequently combined with other cytotoxics. In Japan, cisplatin has been used successfully at low doses in combination with 5-FU based regimens and appears to achieve a synergistic effect, but controlled data are not yet available. More recently oxaliplatin (Europe) and nedaplatin (in Japan) have been introduced, but their clinical roles in therapy have yet to be established. One of the limiting features of the first generation of platinum compounds is that a significant proportion of tumours develop cross resistance to platins due to either changes in uptake or excretion, intracellular detoxification or accelerated DNA repair. The forum discussed the possibility for the development of better new platinum compounds, A new platin agent which had lower toxicity and higher efficacy across a wide range of cancers without the development of resistance would be a significant step forward. If the tolerability profile was suitable, an oral formulation may improve the quality of life for patients but this must not be at the expense of efficacy. Even after the introduction of new target based drugs, platinum cytotoxics are likely to be used to reduce the tumour mass and in some cases can be expected to potentiate the effects of the new agents. In preclinical studies, ZD0473 has been shown to by-pass some major mechanisms of resistance and has the potential to achieve these objectives and is now being evaluated in clinical studies in both Japan and the West. PMID:11383210

  12. Quantum chemical topology study of the water-platinum(II) interaction.

    PubMed

    Bergès, Jacqueline; Fourré, Isabelle; Pilmé, Julien; Kozelka, Jiri

    2013-02-01

    The "inverse hydration" of neutral complexes of Pt(II) by an axial water molecule, whose one OH-bond is oriented toward Pt, has been the subject of recent works, theoretical as well as experimental. To study the influence of the ligands on this non-conventional H-bond, we extend here our previous energy calculations, using the second-order Moeller-Plesset perturbation theory (MP2) method together with the Dolg-Pélissier pseudopotential for platinum, to various neutral complexes including the well-known chemotherapeutic agent "cisplatin". The stabilization energy, depending on the nature and the configuration of platinum ligands, is dominated by the same important dispersive component, for all the investigated complexes. For a further characterization of this particular H-bond, we used the atoms in molecules theory (AIM) and the topological analysis of the electron localization function (ELF). The charge transfer occurring from the complex to the water molecule and the Laplacian of the density at the bond critical point between water and Pt are identified as interesting AIM descriptors of this non-conventional H-bond. Beyond this AIM analysis, we show that the polarization of the ELF bonding O-H basin involved in the non-conventional H-bond is enhanced during the approach of the water molecule to the Pt complexes. When the water medium, treated in an implicit solvation model, is taken into account, the interaction energies become independent on the nature and configuration of platinum ligands. However, the topological descriptors remain qualitatively unchanged. PMID:23347164

  13. Getting Acquainted: An Induction Training Guide for First-Year Extension Agents. Suggestions for Completing Certain Learning Experiences Included in the Induction Training Guide; a Supplement to "Getting Acquainted."

    ERIC Educational Resources Information Center

    Collings, Mary Louise; Gassie, Edward W.

    An induction guide to help the extension agent get acquainted with his role and suggestions for completing learning experiences that are included in the guide comprise this two-part publication. The training guide learning experiences, a total of 25, are made up of: Objectives of the New Worker; When Completed; Learning Experiences; Person(s)…

  14. Bioavailability of platinum emitted from automobile exhaust.

    PubMed

    Artelt, S; Kock, H; Nachtigall, D; Heinrich, U

    1998-08-01

    A model substance was used which is similar in respect to platinum content of exhaust particles emitted from a three-way-catalytic converter equipped engine. The bioavailability of platinum from such exhaust particles and the kind of platinum species formed in vivo were assessed. An in vitro solubility test showed a solubility of approximately 10 percent of platinum content of the model substance in physiological sodium chloride solution. Two short-term animal studies (8 days) were performed. In all examined rat tissues and body fluids platinum could be detected. In addition, the contribution of the overall bioavailability caused by swallowing a certain amount of the intratracheally applied platinum was evaluated by oral application. It was very low. An analytical method was developed to determine platinum species. Synthetic samples (matrix with a platinum standard solution) were analysed. In rat bronchoalveolar lavage spiked with a platinum standard solution only low molecular complexed platinum was found whereas in rat blood plasma all platinum was bound to proteins. In ongoing studies, the model substance is being tested in a three month rat inhalation study. PMID:9820662

  15. Nanocarriers for delivery of platinum anticancer drugs☆

    PubMed Central

    Oberoi, Hardeep S.; Nukolova, Natalia V.; Kabanov, Alexander V.; Bronich, Tatiana K.

    2014-01-01

    Platinum based anticancer drugs have revolutionized cancer chemotherapy, and continue to be in widespread clinical use especially for management of tumors of the ovary, testes, and the head and neck. However, several dose limiting toxicities associated with platinum drug use, partial anti-tumor response in most patients, development of drug resistance, tumor relapse, and many other challenges have severely limited the patient quality of life. These limitations have motivated an extensive research effort towards development of new strategies for improving platinum therapy. Nanocarrier-based delivery of platinum compounds is one such area of intense research effort beginning to provide encouraging preclinical and clinical results and may allow the development of the next generation of platinum chemotherapy. This review highlights current understanding on the pharmacology and limitations of platinum compounds in clinical use, and provides a comprehensive analysis of various platinum–polymer complexes, micelles, dendrimers, liposomes and other nanoparticles currently under investigation for delivery of platinum drugs. PMID:24113520

  16. Discovery and basic pharmacology of erythropoiesis-stimulating agents (ESAs), including the hyperglycosylated ESA, darbepoetin alfa: an update of the rationale and clinical impact.

    PubMed

    Kiss, Zoltán; Elliott, Steven; Jedynasty, Kinga; Tesar, Vladimír; Szegedi, János

    2010-04-01

    Cloning of the human erythropoietin (EPO) gene and development of the first recombinant human erythropoietin (rHuEPO) drug were truly breakthroughs. This allowed a deeper understanding of the structure and pharmacology of rHuEpo, which in turn inspired the discovery and development of additional erythropoiesis-stimulating agents (ESAs). In vivo specific activity and serum half-life of rHuEPO are influenced by the amount and structure of the attached carbohydrate. Increased numbers of sialic acids on carbohydrate attached to rHuEPO correlated with a relative increase in in-vivo-specific activity and increased serum half-life. The effect of increasing the number of sialic-acid-containing carbohydrates on in-vivo-specific activity was explored. Initial research focused on solving the problem of how the protein backbone could be engineered so a cell would add more carbohydrate to it. Additional work resulted in darbepoetin alfa, a longer-acting molecule with two additional carbohydrate chains. PMID:20127232

  17. Article having an improved platinum-aluminum-hafnium protective coating

    NASA Technical Reports Server (NTRS)

    Nagaraj, Bangalore Aswatha (Inventor); Williams, Jeffrey Lawrence (Inventor)

    2005-01-01

    An article protected by a protective coating has a substrate and a protective coating having an outer layer deposited upon the substrate surface and a diffusion zone formed by interdiffusion of the outer layer and the substrate. The protective coating includes platinum, aluminum, no more than about 2 weight percent hafnium, and substantially no silicon. The outer layer is substantially a single phase.

  18. Novel Anticancer Platinum(IV) Complexes with Adamantylamine: Their Efficiency and Innovative Chemotherapy Strategies Modifying Lipid Metabolism.

    PubMed

    Kozubík, Alois; Vaculová, Alena; Soucek, Karel; Vondrácek, Jan; Turánek, Jaroslav; Hofmanová, Jirina

    2008-01-01

    The impressive impact of cisplatin on cancer on one side and severe side effects, as well as the development of drug resistance during treatment on the other side, were the factors motivating scientists to design and synthesize new more potent analogues lacking disadvantages of cisplatin. Platinum(IV) complexes represent one of the perspective groups of platinum-based drugs. In this review, we summarize recent findings on both in vitro and in vivo effects of platinum(IV) complexes with adamantylamine. Based on a literary overview of the mechanisms of activity of platinum-based cytostatics, we discuss opportunities for modulating the effects of novel platinum complexes through interactions with apoptotic signaling pathways and with cellular lipids, including modulations of the mitochondrial cell death pathway, oxidative stress, signaling of death ligands, lipid metabolism/signaling, or intercellular communication. These approaches might significantly enhance the efficacy of both novel and established platinum-based cytostatics. PMID:18414587

  19. Synthesis of nanoscaled platinum particles (NSPP): their role in performance improvement of ionic polymer-metal composite (IPMC) artificial muscles

    NASA Astrophysics Data System (ADS)

    Kim, Kwang J.; Shahinpoor, Mohsen

    2001-07-01

    In this work the synthesis of nano-scaled platinum particles by a chemical reducing technique within an ion-exchange membrane has been performed. It is desirable to gain a fundamental knowledge and understanding of the properties of small nano-scaled platinum particles within ion-exchange membranes, which can affect the performance of Ionic Polymer-Metal Composite (IPMC) artificial muscles. In IPMC artificial muscle applications, the finite size of platinum particles is believed to strongly influence their properties. This might be related to a platinum surface effect originating from the electronic surface states of platinum particles that differ from the bulk states. In order to address this issue, we have attempted to synthesize small platinum particles having different size distributions by using protective agents. Further, we have characterized them as well. For IPMC artificial muscles, the presence of such nano-scale platinum particles minimizes the solvent- leakage from the surface electrodes. This in turn improves their performance dramatically. A successfully fabricated IPMC artificial muscle with nano-Platinum particles has shown a significantly improved force density as much as 100% than that of the conventional IPMC.

  20. cis-platinum and ovarian carcinoma. In vitro chemosensitivity of cultured tumour cells from patients receiving high dose cis-platinum as first line treatment.

    PubMed Central

    Wilson, A. P.; Ford, C. H.; Newman, C. E.; Howell, A.

    1987-01-01

    A study on the in vitro sensitivity of tumour cells from patients with ovarian cancer has been carried out in parallel with a clinical study designed to evaluate the role of high-dose cis-platinum (CIS) as first-line chemotherapy. A total of 50 samples from 102 patients have been successfully cultured and screened for in vitro chemosensitivity to 7 drugs, including CIS. The malignant nature of cells growing in culture was confirmed using a combination of karyology, morphology and immunohistochemical staining with HMFG2. Tumours were graded as sensitive (less than 40% of control 3H-leucine incorporation), intermediate (41-60% of control) or resistant (greater than 61% of control) to CIS. Correlation of in vitro sensitivity to cis-platinum with clinical response to cis-platinum assessed using CT scan and second-look laparotomy, showed positive correlation in 9/11 (89%) patients (8 = S/S; 1 = R/R); positive correlation between in vitro sensitivity to phosphoramide mustard and clinical response was also found in 4/6 patients receiving cyclophosphamide (3 = S/S; 1 = R/R). All patients with sensitive tumours showed a clinical response to cis-platinum. Comparison of cis-platinum sensitivity with sensitivity to phosphoramide mustard and melphalan showed that some tumours were sensitive only to cis-platinum; resistance to cis-platinum and sensitivity to phosphoramide mustard/melphalan was an infrequent occurrence. Some tumours which were resistant to cis-platinum showed sensitivity to adriamycin and bleomycin, particularly those from untreated patients. Sensitivity to 5-fluorouracil and resistance to cis-platinum was found in approximately equal proportions of tumours in both the treated and untreated groups. PMID:3435704

  1. Active targeting of cancer cells using folic acid-conjugated platinum nanoparticles

    NASA Astrophysics Data System (ADS)

    Teow, Yiwei; Valiyaveettil, Suresh

    2010-12-01

    Interaction of nanoparticles with human cells is an interesting topic for understanding toxicity and developing potential drug candidates. Water soluble platinum nanoparticles were synthesized viareduction of hexachloroplatinic acid using sodium borohydride in the presence of capping agents. The bioactivity of folic acid and poly(vinyl pyrrolidone) capped platinum nanoparticles (Pt-nps) has been investigated using commercially available cell lines. In the cell viability experiments, PVP-capped nanoparticles were found to be less toxic (>80% viability), whereas, folic acid-capped platinum nanoparticles showed a reduced viability down to 24% after 72 h of exposure at a concentration of 100 μg ml-1 for MCF7 breast cancer cells. Such toxicity, combined with the possibility to incorporate functional organic molecules as capping agents, can be used for developing new drug candidates.

  2. Surface characterization of platinum electrodes.

    PubMed

    Solla-Gullón, José; Rodríguez, Paramaconi; Herrero, Enrique; Aldaz, Antonio; Feliu, Juan M

    2008-03-14

    The quantitative analysis of the different surface sites on platinum samples is attempted from pure voltammetric data. This analysis requires independent knowledge of the fraction of two-dimensional (111) and (100) domains. Specific site-probe reactions are employed to achieve this goal. Irreversibly-adsorbed bismuth and tellurium have been revealed to be sensitive to the presence of (111) terrace domains of different width whereas almost all sites involved in (100) ordered domains have been characterized through germanium adatoms. The experimental protocol follows that used with well-defined single-crystal electrodes and, therefore, requires careful control of the surface cleanliness. Platinum basal planes and their vicinal stepped surfaces have been employed to obtain calibration plots between the charge density measured under the adatom redox peak, specific for the type of surface site, and the corresponding terrace size. The evaluation of the (100) bidimensional domains can also be achieved using the voltammetric profiles, once the fraction of (111) ordered domains present in the polyoriented platinum has been determined and their featureless contribution has been subtracted from the whole voltammetric response. Using that curve, it is possible to perform a deconvolution of the adsorption states of the polycrystalline sample different from those related to (111) domains. The fraction of (100)-related states in the deconvoluted voltammogram can then be compared to that expected from the independent estimation coming from the charge involved in the redox process undergone by the irreversibly-adsorbed germanium and thus check the result of the deconvolution. The information about the surface-site distribution can also be applied to analyze the voltammetric profile of nanocrystalline platinum electrodes. PMID:18309392

  3. Phosphoric acid fuel cell platinum use study

    NASA Technical Reports Server (NTRS)

    Lundblad, H. L.

    1983-01-01

    The U.S. Department of Energy is promoting the private development of phosphoric acid fuel cell (PAFC) power plants for terrestrial applications. Current PAFC technology utilizes platinum as catalysts in the power electrodes. The possible repercussions that the platinum demand of PAFC power plant commercialization will have on the worldwide supply and price of platinum from the outset of commercialization to the year 2000 are investigated. The platinum demand of PAFC commercialization is estimated by developing forecasts of platinum use per unit of generating capacity and penetration of PAFC power plants into the electric generation market. The ability of the platinum supply market to meet future demands is gauged by assessing the size of platinum reserves and the capability of platinum producers to extract, refine and market sufficient quantities of these reserves. The size and timing of platinum price shifts induced by the added demand of PAFC commercialization are investigated by several analytical methods. Estimates of these price shifts are then used to calculate the subsequent effects on PAFC power plant capital costs.

  4. Platinum- and platinum alloy-coated palladium and palladium alloy particles and uses thereof

    DOEpatents

    Adzic, Radoslav; Zhang, Junliang; Mo, Yibo; Vukmirovic, Miomir Branko

    2010-04-06

    The present invention relates to particle and nanoparticle composites useful as oxygen-reduction electrocatalysts. The particle composites are composed of a palladium or palladium-alloy particle or nanoparticle substrate coated with an atomic submonolayer, monolayer, bilayer, or trilayer of zerovalent platinum atoms. The invention also relates to a catalyst and a fuel cell containing the particle or nanoparticle composites of the invention. The invention additionally includes methods for oxygen reduction and production of electrical energy by using the particle and nanoparticle composites of the invention.

  5. Acute and chronic nephrotoxicity of platinum nanoparticles in mice

    NASA Astrophysics Data System (ADS)

    Yamagishi, Yoshiaki; Watari, Akihiro; Hayata, Yuya; Li, Xiangru; Kondoh, Masuo; Yoshioka, Yasuo; Tsutsumi, Yasuo; Yagi, Kiyohito

    2013-09-01

    Platinum nanoparticles are being utilized in various industrial applications, including in catalysis, cosmetics, and dietary supplements. Although reducing the size of the nanoparticles improves the physicochemical properties and provides useful performance characteristics, the safety of the material remains a major concern. The aim of the present study was to evaluate the biological effects of platinum particles less than 1 nm in size (snPt1). In mice administered with a single intravenous dose of snPt1, histological analysis revealed necrosis of tubular epithelial cells and urinary casts in the kidney, without obvious toxic effects in the lung, spleen, and heart. These mice exhibited dose-dependent elevation of blood urea nitrogen, an indicator of kidney damage. Direct application of snPt1 to in vitro cultures of renal cells induced significant cytotoxicity. In mice administered for 4 weeks with twice-weekly intraperitoneal snPt1, histological analysis of the kidney revealed urinary casts, tubular atrophy, and inflammatory cell accumulation. Notably, these toxic effects were not observed in mice injected with 8-nm platinum particles, either by single- or multiple-dose administration. Our findings suggest that exposure to platinum particles of less than 1 nm in size may induce nephrotoxicity and disrupt some kidney functions. However, this toxicity may be reduced by increasing the nanoparticle size.

  6. A nanohybrid of platinum nanoparticles-porous ZnO-hemin with electrocatalytic activity to construct an amplified immunosensor for detection of influenza.

    PubMed

    Yang, Zhe-Han; Zhuo, Ying; Yuan, Ruo; Chai, Ya-Qin

    2016-04-15

    In this work, a nanohybrid of platinum nanoparticles-porous ZnO spheres-hemin (Pt-pZnO-hemin) was synthesized for construction of alkaline phosphatase-based immunosensor for detection of influenza. Briefly, porous ZnO spheres (pZnO) were prepared using soluble starches as the capping agent, followed by surface functionalization of platinum nanoparticles via a hydrothermal method (Pt-pZnO). Then, hemin with carboxylic functionality was spontaneously adsorbed onto Pt-pZnO by ester-like binding between carboxylic group of hemin and ZnO. Compared with platinum nanoparticles and hemin, the resulting Pt-pZnO-hemin nanohybrid showed more excellent electrocatalysis activity toward 1-naphthol (1-NP). Taking advantage of the Pt-pZnO-hemin, we have developed an amplified electrochemical immunosensor based on in situ generation of redox probe by alkaline phosphatase (ALP) and Pt-pZnO-hemin as signal enhancer. Herein, electrochemically active 1-NP was generated by enzymatic hydrolysis of inactive 1-naphthyl phosphate by ALP, then Pt-pZnO-hemin was used as catalyst to catalytically oxidize 1-NP, resulting in electrochemical signal amplification. Furthermore, in comparison with other nanomaterials including Au-pZnO, Pt-pZnO and Au-pZnO-hemin, the excellent catalytical property of Pt-pZnO-hemin make it a promising nanohybrid material for ALP-based immunosensor for signal amplification. PMID:26649489

  7. DNA-PK mediates AKT activation and apoptosis inhibition in clinically acquired platinum resistance.

    PubMed

    Stronach, Euan A; Chen, Michelle; Maginn, Elaina N; Agarwal, Roshan; Mills, Gordon B; Wasan, Harpreet; Gabra, Hani

    2011-11-01

    Clinical resistance to chemotherapy is a frequent event in cancer treatment and is closely linked to poor outcome. High-grade serous (HGS) ovarian cancer is characterized by p53 mutation and high levels of genomic instability. Treatment includes platinum-based chemotherapy and initial response rates are high; however, resistance is frequently acquired, at which point treatment options are largely palliative. Recent data indicate that platinum-resistant clones exist within the sensitive primary tumor at presentation, implying resistant cell selection after treatment with platinum chemotherapy. The AKT pathway is central to cell survival and has been implicated in platinum resistance. Here, we show that platinum exposure induces an AKT-dependent, prosurvival, DNA damage response in clinically platinum-resistant but not platinum-sensitive cells. AKT relocates to the nucleus of resistant cells where it is phosphorylated specifically on S473 by DNA-dependent protein kinase (DNA-PK), and this activation inhibits cisplatin-mediated apoptosis. Inhibition of DNA-PK or AKT, but not mTORC2, restores platinum sensitivity in a panel of clinically resistant HGS ovarian cancer cell lines: we also demonstrate these effects in other tumor types. Resensitization is associated with prevention of AKT-mediated BAD phosphorylation. Strikingly, in patient-matched sensitive cells, we do not see enhanced apoptosis on combining cisplatin with AKT or DNA-PK inhibition. Insulin-mediated activation of AKT is unaffected by DNA-PK inhibitor treatment, suggesting that this effect is restricted to DNA damage-mediated activation of AKT and that, clinically, DNA-PK inhibition might prevent platinum-induced AKT activation without interfering with normal glucose homeostasis, an unwanted toxicity of direct AKT inhibitors. PMID:22131882

  8. DNA-PK Mediates AKT Activation and Apoptosis Inhibition in Clinically Acquired Platinum Resistance12

    PubMed Central

    Stronach, Euan A; Chen, Michelle; Maginn, Elaina N; Agarwal, Roshan; Mills, Gordon B; Wasan, Harpreet; Gabra, Hani

    2011-01-01

    Clinical resistance to chemotherapy is a frequent event in cancer treatment and is closely linked to poor outcome. High-grade serous (HGS) ovarian cancer is characterized by p53 mutation and high levels of genomic instability. Treatment includes platinum-based chemotherapy and initial response rates are high; however, resistance is frequently acquired, at which point treatment options are largely palliative. Recent data indicate that platinum-resistant clones exist within the sensitive primary tumor at presentation, implying resistant cell selection after treatment with platinum chemotherapy. The AKT pathway is central to cell survival and has been implicated in platinum resistance. Here, we show that platinum exposure induces an AKT-dependent, prosurvival, DNA damage response in clinically platinum-resistant but not platinum-sensitive cells. AKT relocates to the nucleus of resistant cells where it is phosphorylated specifically on S473 by DNA-dependent protein kinase (DNA-PK), and this activation inhibits cisplatin-mediated apoptosis. Inhibition of DNA-PK or AKT, but not mTORC2, restores platinum sensitivity in a panel of clinically resistant HGS ovarian cancer cell lines: we also demonstrate these effects in other tumor types. Resensitization is associated with prevention of AKT-mediated BAD phosphorylation. Strikingly, in patient-matched sensitive cells, we do not see enhanced apoptosis on combining cisplatin with AKT or DNA-PK inhibition. Insulin-mediated activation of AKT is unaffected by DNA-PK inhibitor treatment, suggesting that this effect is restricted to DNA damage-mediated activation of AKT and that, clinically, DNA-PK inhibition might prevent platinum-induced AKT activation without interfering with normal glucose homeostasis, an unwanted toxicity of direct AKT inhibitors. PMID:22131882

  9. Allergy to complex platinum salts: A historical prospective cohort study.

    PubMed Central

    Niezborala, M; Garnier, R

    1996-01-01

    OBJECTIVE: To assess the incidence of allergy to complex platinum salts in a platinum refinery. METHODS: A historical prospective cohort study was carried out on 77 workers (67 men) who started work between 1 January 1979 and 31 December 1991 and who were not atopic on skin prick tests to three common allergens at the time of recruitment. Skin prick tests with complex platinum salts were carried out and diagnosis of allergy to complex platinum salts made by the company's doctor. Skin tests and medical examinations were carried out routinely every six months. Follow up was until 30 September 1992 or until leaving refinery work. RESULTS: 18 workers developed a positive result on skin tests and 23 developed symptoms, including all 18 subjects with positive skin tests; the probability of surviving (95% confidence interval (95% CI)) for 72 months after joining the company, with negative skin test results was 0.67 (0.51-0.79) or with no symptoms was 0.63 (0.49-0.75). The incidence of positive skin tests and symptoms was highest during the first two years of work. Symptoms occurred more frequently in September and October than during the other months of the year. The exclusion of atopic subjects did not seem to have resulted in a lower incidence of sensitisation. Smoking was a significant predictive factor for both positive skin tests (estimated relative risk 5.53) and symptoms (4.70). CONCLUSION: The findings confirm that smoking is and that atopy may not be a high risk factor for the development of allergy to complex platinum salts. The high incidence of sensitisation and the available data on the clinical course of sensitised workers show that sensitised workers must be promptly and completely removed from exposure. PMID:8664963

  10. INDUCTION OF TRISOMICS BY PLATINUM DIAMINODINITRODICHLORIDE

    EPA Science Inventory

    Trisomics were produced in the pollen mother cells of Pennisetum americanum (L) K. Schum plants resulting from seeds treated with M to the minus 6th power platinum diaminodinitrodichloride. On the basis of the preliminary study the relative potency of cis-Platinum diaminodinitrod...

  11. Platinum electrodes for electrochemical detection of bacteria

    NASA Technical Reports Server (NTRS)

    Wilkins, J. R.

    1979-01-01

    Bacteria is detected electro-chemically by measuring evolution of hydrogen in test system with platinum and reference electrode. Using system, electrodes of platinum are used to detect and enumerate varieties of gram-positive and gram-negative organisms compared in different media.

  12. Preparation of Carbon-Platinum-Ceria and Carbon-Platinum-Cerium catalysts and its application in Polymer Electrolyte Fuel Cell: Hydrogen, Methanol, and Ethanol

    NASA Astrophysics Data System (ADS)

    Guzman Blas, Rolando Pedro

    This thesis is focused on fuel cells using hydrogen, methanol and ethanol as fuel. Also, in the method of preparation of catalytic material for the anode: Supercritical Fluid Deposition (SFD) and impregnation method using ethylenediaminetetraacetic acid (EDTA) as a chelating agent. The first part of the thesis describes the general knowledge about Hydrogen Polymer Exchange Membrane Fuel Cell (HPEMFC),Direct Methanol Fuel Cell (DMFC) and Direct Ethanol Fuel Cell (DEFC), as well as the properties of Cerium and CeO2 (Ceria). The second part of the thesis describes the preparation of catalytic material by Supercritical Fluid Deposition (SFD). SFD was utilized to deposit Pt and ceria simultaneously onto gas diffusion layers. The Pt-ceria catalyst deposited by SFD exhibited higher methanol oxidation activity compared to the platinum catalyst alone. The linear sweep traces of the cathode made for the methanol cross over study indicate that Pt-Ceria/C as the anode catalyst, due to its better activity for methanol, improves the fuel utilization, minimizing the methanol permeation from anode to cathode compartment. The third and fourth parts of the thesis describe the preparation of material catalytic material Carbon-Platinum-Cerium by a simple and cheap impregnation method using EDTA as a chelating agent to form a complex with cerium (III). This preparation method allows the mass production of the material catalysts without additional significant cost. Fuel cell polarization and power curves experiments showed that the Carbon-Platinum-Cerium anode materials exhibited better catalytic activity than the only Vulcan-Pt catalysts for DMFC, DEFC and HPEMFC. In the case of Vulcan-20%Pt-5%w Cerium, this material exhibits better catalytic activity than the Vulcan-20%Pt in DMFC. In the case of Vulcan-40% Pt-doped Cerium, this material exhibits better catalytic activity than the Vulcan-40% Pt in DMFC, DEFC and HPEMFC. Finally, I propose a theory that explains the reason why the

  13. Guanidine complexes of platinum: a theoretical study.

    PubMed

    Marin-Luna, Marta; Sanchez-Sanz, Goar; O'Sullivan, Patrick; Rozas, Isabel

    2014-07-24

    We have studied theoretically the complexes of model N-phenylguanidine/ium derivatives with PtCl3(-) and PtCl2 in different coordinating modes (mono- and bidentate) with different N atoms of the guanidine/ium moiety using the B3LYP/6-31+G** and LANL2DZ mixed basis set. This will aid the understanding of the complexation between platinum and the guanidine or guanidinium moiety in order to design dual anticancer agents that combine a guanidine-based DNA minor groove binder and a cisplatin-like moiety. Calculated interaction and relative energies, analysis of the electron density, and examination of the orbital interactions indicate that the most stable type of complex is that with a monodentate interaction between PtCl3(-) and guanidinium established through one of the NH2 groups. Next, we optimized the structure of three bis-guanidinium diaromatic systems developed in our group as DNA minor groove binders and their complexation with PtCl3(-), finding that the formation of Pt complexes of these minor groove binders is favorable and would produce stable monodentate coordinated systems. PMID:24988181

  14. Molecular characteristics and in vitro susceptibility to antimicrobial agents, including the des-fluoro(6) quinolone DX-619, of Panton-Valentine leucocidin-positive methicillin-resistant Staphylococcus aureus isolates from the community and hospitals.

    PubMed

    Yamamoto, Tatsuo; Dohmae, Soshi; Saito, Kohei; Otsuka, Taketo; Takano, Tomomi; Chiba, Megumi; Fujikawa, Katsuko; Tanaka, Mayumi

    2006-12-01

    Highly virulent, community-acquired methicillin-resistant Staphylococcus aureus (MRSA) strains with Panton-Valentine leucocidin (PVL) genes have been found increasingly worldwide. Among a total of 2,101 MRSA strains isolated from patients in hospitals in Japan, two were positive for PVL genes. One strain was identified as a community-acquired MRSA strain with genotype sequence type 30 (ST30) and spa (staphylococcal protein A gene) type 19 from Japan and was resistant only to beta-lactam antimicrobial agents. The other strain was closely related to PVL+ multidrug-resistant, hospital-acquired MRSA strains (ST30, spa type 43) derived from nosocomial outbreaks in the 1980s to 1990s in Japan but with a divergent sequence type, ST765 (a single-locus variant of ST30). Twenty-two PVL+ MRSA strains, including those from Japan and those from other countries with various sequence types (ST1, ST8, ST30, ST59, and ST80) and genotypes, were examined for susceptibility to 31 antimicrobial agents. Among the agents, DX-619, a des-fluoro(6) quinolone, showed the greatest activity, followed by rifampin and sitafloxacin, a fluoroquinolone. The data suggest that DX-619 exhibits a superior activity against PVL+ MRSA strains with various virulence genetic traits from the community as well as from hospitals. PMID:17043124

  15. Platinum metallization for MEMS application

    PubMed Central

    Guarnieri, Vittorio; Biazi, Leonardo; Marchiori, Roberto; Lago, Alexandre

    2014-01-01

    The adherence of Platinum thin film on Si/SiO2 wafer was studies using Chromium, Titanium or Alumina (Cr, Ti, Al2O3) as interlayer. The adhesion of Pt is a fundamental property in different areas, for example in MEMS devices, which operate at high temperature conditions, as well as in biomedical applications, where the problem of adhesion of a Pt film to the substrate is known as a major challenge in several industrial applications health and in biomedical devices, such as for example in the stents.1-4 We investigated the properties of Chromium, Titanium, and Alumina (Cr, Ti, and Al2O3) used as adhesion layers of Platinum (Pt) electrode. Thin films of Chromium, Titanium and Alumina were deposited on Silicon/Silicon dioxide (Si/SiO2) wafer by electron beam. We introduced Al2O3 as a new adhesion layer to test the behavior of the Pt film at higher temperature using a ceramic adhesion thin film. Electric behaviors were measured for different annealing temperatures to know the performance for Cr/Pt, Ti/Pt, and Al2O3/Pt metallic film in the gas sensor application. All these metal layers showed a good adhesion onto Si/SiO2 and also good Au wire bondability at room temperature, but for higher temperature than 400 °C the thin Cr/Pt and Ti/Pt films showed poor adhesion due to the atomic inter-diffusion between Platinum and the metal adhesion layers.5 The proposed Al2O3/Pt ceramic-metal layers confirmed a better adherence for the higher temperatures tested. PMID:24743057

  16. Extended Platinum Nanotubes as Fuel Cell Catalysts

    SciTech Connect

    Alia, S.; Pivovar, B. S.; Yan, Y.

    2012-01-01

    Energy consumption has relied principally on fossil fuels as an energy source; fuel cells, however, can provide a clean and sustainable alternative, an answer to the depletion and climate change concerns of fossil fuels. Within proton exchange membrane fuel cells, high catalyst cost and poor durability limit the commercial viability of the device. Recently, platinum nanotubes (PtNTs) were studied as durable, active catalysts, providing a platform to meet US Department of Energy vehicular activity targets.[1] Porous PtNTs were developed to increase nanotube surface area, improving mass activity for oxygen reduction without sacrificing durability.[2] Subsurface platinum was then replaced with palladium, forming platinum-coated palladium nanotubes.[3] By forming a core shell structure, platinum utilization was increased, reducing catalyst cost. Alternative substrates have also been examined, modifying platinum surface facets and increasing oxygen reduction specific activity. Through modification of the PtNT platform, catalyst limitations can be reduced, ensuring a commercially viable device.

  17. Comparison of the effects of the oral anticancer platinum(IV) complexes oxoplatin and metabolite cis-diammine-tetrachlorido-platinum(IV) on global gene expression of NCI-H526 cells

    PubMed Central

    Olszewski, Ulrike; Ulsperger, Ernst; Geissler, Klaus; Hamilton, Gerhard

    2011-01-01

    Platinum(IV) coordination complexes like oxoplatin (cis,cis,trans-diammine-dichlorido-dihydroxido-platinum[IV]) show high stability and therefore can be utilized orally for outpatient care. Although oxoplatin is capable of binding directly to DNA after prolonged incubation, platinum(IV) agents are considered to be largely inert prodrugs that are converted to highly cytotoxic platinum(II) compounds by reducing substances, enzymes, or microenviron-mental conditions. Reaction of oxoplatin with 0.1 M hydrogen chloride mimicking gastric acid yields cis-diammine-tetrachlorido-platinum(IV) (DATCP[IV]), which exhibits two-fold increased activity. The presence of chlorides as ligands in the axial position results in a high reduction potential that favors transformation to platinum(II) complexes. In this study, the intracellular effect of the highly reactive tetrachlorido derivative was investigated in comparison with an equipotent dose of cisplatin. Genome-wide expression profiling of NCI-H526 small cell lung cancer cells treated with these platinum species revealed clear differences in the expression pattern of affected genes and concerned cellular pathways between DATCP(IV) and cisplatin. Application of DATCP(IV) resulted in extensive downregulation of protein and ATP synthesis, cell cycle regulation, and glycolysis, in contrast to cisplatin, which preferentially targeted glutathione conjugation, pyruvate metabolism, citric acid cycle, and the metabolism of amino acids and a range of carbohydrates. Thus, the oxoplatin metabolite DATCP(IV) constitutes a potent cytotoxic derivative that may be produced by gastric acid or acidic areas prevailing in larger solid tumors, depending on the respective pharmaceutical formulation of oxoplatin. Furthermore, DATCP(IV) exhibits intracellular effects that are clearly different from the expected reduced product cisplatin(II). In conclusion, activation of the platinum(IV) complex oxoplatin seems to involve the generation of a cytotoxic

  18. Salvage chemotherapy with amrubicin and platinum for relapsed thymic carcinoma: experience in six cases.

    PubMed

    Koizumi, Tomonobu; Agatsuma, Toshihiko; Ichiyama, Takashi; Yokoyama, Toshiki; Ushiki, Atsuhito; Komatsu, Yoshimichi; Tanabe, Tsuyoshi; Kobayashi, Takashi; Yoshikawa, Sumiko; Yasuo, Masanori; Yamamoto, Hiroshi; Kubo, Keishi; Hachiya, Tsutomu

    2010-06-01

    It has been reported that cisplatin-based chemotherapy shows beneficial effects in certain patients with advanced thymic carcinoma. However, the usefulness of salvage therapy has not been reported. We focused on a new anthracycline agent, amrubicin, combined with platinum compounds as salvage chemotherapy in patients with thymic carcinoma. Six cases of unresectable and locally advanced thymic carcinoma relapsed from prior cisplatin-containing chemotherapy were treated with amrubicin (30-40 mg/m(2) day 1-3) plus platinum compounds (cisplatin 60 mg/m(2) day 1 or nedaplatin 70 mg/m(2) day 1) chemotherapy as salvage chemotherapy. Two patients showed a partial response. However, Grade 3/4 neutropenia and thrombocytopenia occurred in all and two of the patients, respectively. We conclude that thymic carcinoma is sensitive to platinum-based chemotherapy and that amrubicin appears to have significant activity against thymic carcinoma. The major toxicity is hematological toxicities. PMID:19415537

  19. A Photoactivatable Platinum(IV) Complex Targeting Genomic DNA and Histone Deacetylases.

    PubMed

    Kasparkova, Jana; Kostrhunova, Hana; Novakova, Olga; Křikavová, Radka; Vančo, Ján; Trávníček, Zdeněk; Brabec, Viktor

    2015-11-23

    We report toxic effects of a photoactivatable platinum(IV) complex conjugated with suberoyl-bis-hydroxamic acid in tumor cells. The conjugate exerts, after photoactivation, two functions: activity as both a platinum(II) anticancer drug and histone deacetylase (HDAC) inhibitor in cancer cells. This approach relies on the use of a Pt(IV) pro-drug, acting by two independent mechanisms of biological action in a cooperative manner, which can be selectively photoactivated to a cytotoxic species in and around a tumor, thereby increasing selectivity towards cancer cells. These results suggest that this strategy is a valuable route to design new platinum agents with higher efficacy for photodynamic anticancer chemotherapy. PMID:26458068

  20. Trastuzumab-mediated selective delivery for platinum drug to HER2-positive breast cancer cells.

    PubMed

    Huang, Rong; Sun, Yu; Gao, Qihe; Wang, Qiucui; Sun, Baiwang

    2015-10-01

    Oxaliplatin is used widely as an anticancer drug for clinical treatment. However, its applications are limited because of its poor selectivity. In this work, we described the design, synthesis, and characterization of conjugates combining trastuzumab with a platinum (IV) analog of oxaliplatin, in which the trastuzumab acted as an active targeting agent for HER2-positive cancer cells. Indirect enzyme-linked immunosorbent assay and immunofluorescence study indicated the platinum (IV)-trastuzumab conjugates retained specific binding activity to HER2 overexpressed SK-BR-3 cells. In the presence of ascorbic acid, platinum (IV)-trastuzumab conjugates were reduced to platinum (II) analogs, which could bind to and unwind PUC19 DNA in a manner similar to oxaliplatin. The cytotoxic study was tested on three breast cell lines: SK-BR-3, MCF-7, and MDA-MB-231. Platinum (IV)-trastuzumab conjugates showed promising antiproliferative activity against SK-BR-3 cells, but significantly decreased the inhibition to MDA-MB-231 and MCF-7 cells. The flow cytometric analysis showed that the conjugates arrested the cell cycle mainly at the G2/M phase and killed the cells through an apoptotic pathway. PMID:26186063

  1. Characterization of electrochemically modified polycrystalline platinum surfaces

    SciTech Connect

    Krebs, L.C.; Ishida, Takanobu.

    1991-12-01

    The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between {minus}0.24 and +1.25 V{sub SCE} while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-{rho}-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

  2. Trends in the susceptibility of commonly encountered clinically significant anaerobes and susceptibilities of blood isolates of anaerobes to 16 antimicrobial agents, including fidaxomicin and rifaximin, 2008-2012, northern Taiwan.

    PubMed

    Wang, F D; Liao, C H; Lin, Y T; Sheng, W H; Hsueh, P R

    2014-11-01

    We investigated the antimicrobial resistance trends and profiles of clinical anaerobic isolates in northern Taiwan. Trends in the susceptibility of five commonly encountered clinical anaerobic isolates to seven agents from 2008 to 2012 were measured using the Cochran-Armitage trend test. The minimum inhibitory concentrations (MICs) of 16 antimicrobial agents, including fidaxomicin and rifaximin, against anaerobic blood isolates from two medical centers were determined using the agar dilution method. During the study period, susceptibility data on 11,105 isolates were evaluated. Metronidazole and chloramphenicol retained excellent activities. Around 20-30 % of isolates of Bacteroides and Prevotella species were resistant to ampicillin-sulbactam, cefmetazole, flomoxef, and clindamycin. Of the 507 tested blood isolates, the rates of resistance to commonly used agents were much higher, namely, 16.2 % for amoxicillin-clavulanate, 15.6 % for ampicillin-sulbactam, 24.7 % for cefmetazole, and 36.1 % for clindamycin. Notably, 13.5 % of B. fragilis isolates were resistant to ertapenem. Also, 15.2 % of B. uniformis, 17.2 % of other Bacteroides species, 14.3 % of Prevotella species, and 14 % of Clostridium other than C. perfringens isolates were resistant to moxifloxacin. Cefoperazone-sulbactam was active against most isolates, except for Clostridium species other than perfringens (resistance rate, 18.6 %). Fidaxomicin exerted poor activities against most anaerobes tested (MIC90 of >128 μg/ml for B. fragilis and all isolates), except for C. perfringens (MIC90 of 0.03 μg/ml) and Peptostreptococcus micros (MIC90 of 2 μg/ml). However, rifaximin showed a wide range of susceptibilities against the tested anaerobes (MIC90 of 0.5 μg/ml for B. fragilis). The emergence of resistance to ertapenem and moxifloxacin among bacteremic anaerobes highlights the need for continuous monitoring. PMID:24930042

  3. The level of intracellular glutathione is a key regulator for the induction of stress-activated signal transduction pathways including Jun N-terminal protein kinases and p38 kinase by alkylating agents.

    PubMed Central

    Wilhelm, D; Bender, K; Knebel, A; Angel, P

    1997-01-01

    Monofunctional alkylating agents like methyl methanesulfonate (MMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) are potent inducers of cellular stress leading to chromosomal aberrations, point mutations, and cell killing. We show that these agents induce a specific cellular stress response program which includes the activation of Jun N-terminal kinases/stress-activated protein kinases (JNK/SAPKs), p38 mitogen-activated protein kinase, and the upstream kinase SEK1/MKK4 and which depends on the reaction mechanism of the alkylating agent in question. Similar to another inducer of cellular stress, UV irradiation, damage of nuclear DNA by alkylation is not involved in the MMS-induced response. However, in contrast to UV and other inducers of the JNK/SAPKs and p38 pathways, activation of growth factor and G-protein-coupled receptors does not play a role in the MMS response. We identified the intracellular glutathione (GSH) level as critical for JNK/SAPK activation by MMS: enhancing the GSH level by pretreatment of the cells with GSH or N-acetylcysteine inhibits, whereas depletion of the cellular GSH pool causes hyperinduction of JNK/SAPK activity by MMS. In light of the JNK/SAPK-dependent induction of c-jun and c-fos transcription, and the Jun/Fos-induced transcription of xenobiotic-metabolizing enzymes, these data provide a potential critical role of JNK/SAPK and p38 in the induction of a cellular defense program against cytotoxic xenobiotics such as MMS. PMID:9234735

  4. Antitumor effect of arabinogalactan and platinum complex.

    PubMed

    Starkov, A K; Zamay, T N; Savchenko, A A; Ingevatkin, E V; Titova, N M; Kolovskaya, O S; Luzan, N A; Silkin, P P; Kuznetsova, S A

    2016-03-01

    The article presents the results of investigation of antitumor properties of platinum-arabinogalactan complex. We showed the ability of the complex to inhibit the growth of Ehrlich ascites tumor cells. It is found that the distribution of the platinum-arabinogalactan complex is not specific only for tumor cells in mice. The complex was found in all tissues and organs examined (ascites cells, embryonic cells, kidney, and liver). The mechanism of action of the arabinogalactan-platinum complex may be similar to cisplatin as the complex is able to accumulate in tumor cells. PMID:27193706

  5. Aberrant DNA Damage Response Pathways May Predict the Outcome of Platinum Chemotherapy in Ovarian Cancer

    PubMed Central

    Stefanou, Dimitra T.; Bamias, Aristotelis; Episkopou, Hara; Kyrtopoulos, Soterios A.; Likka, Maria; Kalampokas, Theodore; Photiou, Stylianos; Gavalas, Nikos; Sfikakis, Petros P.; Dimopoulos, Meletios A.; Souliotis, Vassilis L.

    2015-01-01

    Ovarian carcinoma (OC) is the most lethal gynecological malignancy. Despite the advances in the treatment of OC with combinatorial regimens, including surgery and platinum-based chemotherapy, patients generally exhibit poor prognosis due to high chemotherapy resistance. Herein, we tested the hypothesis that DNA damage response (DDR) pathways are involved in resistance of OC patients to platinum chemotherapy. Selected DDR signals were evaluated in two human ovarian carcinoma cell lines, one sensitive (A2780) and one resistant (A2780/C30) to platinum treatment as well as in peripheral blood mononuclear cells (PBMCs) from OC patients, sensitive (n = 7) or resistant (n = 4) to subsequent chemotherapy. PBMCs from healthy volunteers (n = 9) were studied in parallel. DNA damage was evaluated by immunofluorescence γH2AX staining and comet assay. Higher levels of intrinsic DNA damage were found in A2780 than in A2780/C30 cells. Moreover, the intrinsic DNA damage levels were significantly higher in OC patients relative to healthy volunteers, as well as in platinum-sensitive patients relative to platinum-resistant ones (all P<0.05). Following carboplatin treatment, A2780 cells showed lower DNA repair efficiency than A2780/C30 cells. Also, following carboplatin treatment of PBMCs ex vivo, the DNA repair efficiency was significantly higher in healthy volunteers than in platinum-resistant patients and lowest in platinum-sensitive ones (t1/2 for loss of γH2AX foci: 2.7±0.5h, 8.8±1.9h and 15.4±3.2h, respectively; using comet assay, t1/2 of platinum-induced damage repair: 4.8±1.4h, 12.9±1.9h and 21.4±2.6h, respectively; all P<0.03). Additionally, the carboplatin-induced apoptosis rate was higher in A2780 than in A2780/C30 cells. In PBMCs, apoptosis rates were inversely correlated with DNA repair efficiencies of these cells, being significantly higher in platinum-sensitive than in platinum-resistant patients and lowest in healthy volunteers (all P<0.05). We conclude that

  6. Profile of bevacizumab in the treatment of platinum-resistant ovarian cancer: current perspectives

    PubMed Central

    McClung, E Clair; Wenham, Robert M

    2016-01-01

    Patients with platinum-resistant ovarian cancer have progression of disease within 6 months of completing platinum-based chemotherapy. While several chemotherapeutic options exist for the treatment of platinum-resistant ovarian cancer, the overall response to any of these therapies is ~10%, with a median progression-free survival of 3–4 months and a median overall survival of 9–12 months. Bevacizumab (Avastin), a humanized, monoclonal antivascular endothelial growth factor antibody, has demonstrated antitumor activity in the platinum-resistant setting and was recently approved by US Food and Drug Administration for combination therapy with weekly paclitaxel, pegylated liposomal doxorubicin, or topotecan. This review summarizes key clinical trials investigating bevacizumab for recurrent, platinum-resistant ovarian cancer and provides an overview of efficacy, safety, and quality of life data relevant in this setting. While bevacizumab is currently the most studied and clinically available antiangiogenic therapy, we summarize recent studies highlighting novel alternatives, including vascular endothelial growth factor-trap, tyrosine kinase inhibitors, and angiopoietin inhibitor trebananib, and discuss their application for the treatment of platinum-resistant ovarian cancer. PMID:27051317

  7. Innovative use of platinum compounds to selectively detect live microorganisms by polymerase chain reaction.

    PubMed

    Soejima, Takashi; Minami, Jun-Ichi; Xiao, Jin-Zhong; Abe, Fumiaki

    2016-02-01

    PCR cannot distinguish live microorganisms from dead ones. To circumvent this disadvantage, ethidium/propidium-monoazide (EMA/PMA) and psoralen to discriminate live from dead bacteria have been used for 2 decades. These methods require the use of numerous laborious procedures. We introduce an innovative method that uses platinum compounds, which are primarily used as catalysts in organic chemistry and partly used as anti-cancer drugs. Microorganisms are briefly exposed to platinum compounds in vivo, and these compounds penetrate dead (compromised) microorganisms but not live ones and are chelated by chromosomal DNA. The use of platinum compounds permits clear discrimination between live and dead microorganisms in water and milk (including Cronobacter sakazakii and Escherichia coli) via PCR compared with typically used PMA. This platinum-PCR method could enable the specific detection of viable coliforms in milk at a concentration of 5-10 CFU mL(-1) specified by EU/USA regulations after a 4-h process. For sample components, environmental water contains lower levels of PCR inhibitors than milk does, and milk is similar to infant formula, skim milk and blood; thus, the use of the platinum-PCR method could also prevent food poisoning due to the presence of C. sakazakii in dairy products. This method could provide outstanding rapidity for use in environmental/food/clinical tests. Platinum-PCR could also be a substitute for the typical culture-based methods currently used. PMID:26192088

  8. Profile of bevacizumab in the treatment of platinum-resistant ovarian cancer: current perspectives.

    PubMed

    McClung, E Clair; Wenham, Robert M

    2016-01-01

    Patients with platinum-resistant ovarian cancer have progression of disease within 6 months of completing platinum-based chemotherapy. While several chemotherapeutic options exist for the treatment of platinum-resistant ovarian cancer, the overall response to any of these therapies is ~10%, with a median progression-free survival of 3-4 months and a median overall survival of 9-12 months. Bevacizumab (Avastin), a humanized, monoclonal antivascular endothelial growth factor antibody, has demonstrated antitumor activity in the platinum-resistant setting and was recently approved by US Food and Drug Administration for combination therapy with weekly paclitaxel, pegylated liposomal doxorubicin, or topotecan. This review summarizes key clinical trials investigating bevacizumab for recurrent, platinum-resistant ovarian cancer and provides an overview of efficacy, safety, and quality of life data relevant in this setting. While bevacizumab is currently the most studied and clinically available antiangiogenic therapy, we summarize recent studies highlighting novel alternatives, including vascular endothelial growth factor-trap, tyrosine kinase inhibitors, and angiopoietin inhibitor trebananib, and discuss their application for the treatment of platinum-resistant ovarian cancer. PMID:27051317

  9. Photodynamic killing of cancer cells by a Platinum(II) complex with cyclometallating ligand.

    PubMed

    Doherty, Rachel E; Sazanovich, Igor V; McKenzie, Luke K; Stasheuski, Alexander S; Coyle, Rachel; Baggaley, Elizabeth; Bottomley, Sarah; Weinstein, Julia A; Bryant, Helen E

    2016-01-01

    Photodynamic therapy that uses photosensitizers which only become toxic upon light-irradiation provides a strong alternative to conventional cancer treatment due to its ability to selectively target tumour material without affecting healthy tissue. Transition metal complexes are highly promising PDT agents due to intense visible light absorption, yet the majority are toxic even without light. This study introduces a small, photostable, charge-neutral platinum-based compound, Pt(II) 2,6-dipyrido-4-methyl-benzenechloride, complex 1, as a photosensitizer, which works under visible light. Activation of the new photosensitizer at low concentrations (0.1-1 μM) by comparatively low dose of 405 nm light (3.6 J cm(-2)) causes significant cell death of cervical, colorectal and bladder cancer cell lines, and, importantly, a cisplatin resistant cell line EJ-R. The photo-index of the complex is 8. We demonstrate that complex 1 induces irreversible DNA single strand breaks following irradiation, and that oxygen is essential for the photoinduced action. Neither light, nor compound alone led to cell death. The key advantages of the new drug include a remarkably fast accumulation time (diffusion-controlled, minutes), and photostability. This study demonstrates a highly promising new agent for photodynamic therapy, and attracts attention to photostable metal complexes as viable alternatives to conventional chemotherapeutics, such as cisplatin. PMID:26940077

  10. Photodynamic killing of cancer cells by a Platinum(II) complex with cyclometallating ligand

    NASA Astrophysics Data System (ADS)

    Doherty, Rachel E.; Sazanovich, Igor V.; McKenzie, Luke K.; Stasheuski, Alexander S.; Coyle, Rachel; Baggaley, Elizabeth; Bottomley, Sarah; Weinstein, Julia A.; Bryant, Helen E.

    2016-03-01

    Photodynamic therapy that uses photosensitizers which only become toxic upon light-irradiation provides a strong alternative to conventional cancer treatment due to its ability to selectively target tumour material without affecting healthy tissue. Transition metal complexes are highly promising PDT agents due to intense visible light absorption, yet the majority are toxic even without light. This study introduces a small, photostable, charge-neutral platinum-based compound, Pt(II) 2,6-dipyrido-4-methyl-benzenechloride, complex 1, as a photosensitizer, which works under visible light. Activation of the new photosensitizer at low concentrations (0.1–1 μM) by comparatively low dose of 405 nm light (3.6 J cm‑2) causes significant cell death of cervical, colorectal and bladder cancer cell lines, and, importantly, a cisplatin resistant cell line EJ-R. The photo-index of the complex is 8. We demonstrate that complex 1 induces irreversible DNA single strand breaks following irradiation, and that oxygen is essential for the photoinduced action. Neither light, nor compound alone led to cell death. The key advantages of the new drug include a remarkably fast accumulation time (diffusion-controlled, minutes), and photostability. This study demonstrates a highly promising new agent for photodynamic therapy, and attracts attention to photostable metal complexes as viable alternatives to conventional chemotherapeutics, such as cisplatin.

  11. Photodynamic killing of cancer cells by a Platinum(II) complex with cyclometallating ligand

    PubMed Central

    Doherty, Rachel E.; Sazanovich, Igor V.; McKenzie, Luke K.; Stasheuski, Alexander S.; Coyle, Rachel; Baggaley, Elizabeth; Bottomley, Sarah; Weinstein, Julia A.; Bryant, Helen E.

    2016-01-01

    Photodynamic therapy that uses photosensitizers which only become toxic upon light-irradiation provides a strong alternative to conventional cancer treatment due to its ability to selectively target tumour material without affecting healthy tissue. Transition metal complexes are highly promising PDT agents due to intense visible light absorption, yet the majority are toxic even without light. This study introduces a small, photostable, charge-neutral platinum-based compound, Pt(II) 2,6-dipyrido-4-methyl-benzenechloride, complex 1, as a photosensitizer, which works under visible light. Activation of the new photosensitizer at low concentrations (0.1–1 μM) by comparatively low dose of 405 nm light (3.6 J cm−2) causes significant cell death of cervical, colorectal and bladder cancer cell lines, and, importantly, a cisplatin resistant cell line EJ-R. The photo-index of the complex is 8. We demonstrate that complex 1 induces irreversible DNA single strand breaks following irradiation, and that oxygen is essential for the photoinduced action. Neither light, nor compound alone led to cell death. The key advantages of the new drug include a remarkably fast accumulation time (diffusion-controlled, minutes), and photostability. This study demonstrates a highly promising new agent for photodynamic therapy, and attracts attention to photostable metal complexes as viable alternatives to conventional chemotherapeutics, such as cisplatin. PMID:26940077

  12. Porous platinum-based catalysts for oxygen reduction

    DOEpatents

    Erlebacher, Jonah D; Snyder, Joshua D

    2014-11-25

    A porous metal that comprises platinum and has a specific surface area that is greater than 5 m.sup.2/g and less than 75 m.sup.2/g. A fuel cell includes a first electrode, a second electrode spaced apart from the first electrode, and an electrolyte arranged between the first and the second electrodes. At least one of the first and second electrodes is coated with a porous metal catalyst for oxygen reduction, and the porous metal catalyst comprises platinum and has a specific surface area that is greater than 5 m.sup.2/g and less than 75 m.sup.2/g. A method of producing a porous metal according to an embodiment of the current invention includes producing an alloy consisting essentially of platinum and nickel according to the formula Pt.sub.xNi.sub.1-x, where x is at least 0.01 and less than 0.3; and dealloying the alloy in a substantially pH neutral solution to reduce an amount of nickel in the alloy to produce the porous metal.

  13. Teaching the Chemistry of Platinum.

    PubMed

    Anderson, Robert G W

    2015-01-01

    Following colonisation of South America by the Spanish, many new naturally occurring substances were sent to Europe. One of these was the silvery, unreactive metal, platinum, discovered in New Grenada in the mid-eighteenth century. It was often found in granular form, associated with gold, and the challenge to chemists was to refine it, produce it as wire or sheet, and determine its chemical properties. This interested the professor of chemistry at the University of Edinburgh, Joseph Black, who was able to obtain samples from London-based Spanish contacts, particularly Ignacio Luzuriaga. This paper examines how Black transmitted his knowledge of the metal to large numbers of students attending his annual course. PMID:26924332

  14. Calibration of platinum resistance thermometers.

    NASA Technical Reports Server (NTRS)

    Sinclair, D. H.; Terbeek, H. G.; Malone, J. H.

    1972-01-01

    Results of five years experience in calibrating about 1000 commercial platinum resistance thermometers (PRT) are reported. These PRT were relatively small and rugged, with ice-point resistances from 200 to 5000 ohms. Calibrations normalized in terms of resistance-difference ratios (Cragoe Z function) were found to be remarkably uniform for five of six different types of PRT tested, and to agree very closely with normalized calibrations of the primary reference standard type PRT. The Z function normalization cancels residual resistances which are not temperature dependent and simplifies interpolation between calibration points when the quality of a given type of PRT has been established in terms of uniform values of the Z function. Measurements at five or six well spaced base-point temperatures with Z interpolation will suffice to calibrate a PRT accurately from 4 to 900 K.

  15. Evaluation of platinum resistance thermometers

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Dillon-Townes, Lawrence A.

    1988-01-01

    An evaluation procedure for the characterization of industrial platinum resistance thermometers (PRTs) for use in the temperature range -120 to 160 C was investigated. This evaluation procedure consisted of calibration, thermal stability and hysteresis testing of four surface measuring PRTs. Five different calibration schemes were investigated for these sensors. The IPTS-68 formulation produced the most accurate result, yielding average sensor systematic error of 0.02 C and random error of 0.1 C. The sensors were checked for thermal stability by successive and thermal cycling between room temperature, 160 C, and boiling point of nitrogen. All the PRTs suffered from instability and hysteresis. The applicability of the self-heating technique as an in situ method for checking the calibration of PRTs located inside wind tunnels was investigated.

  16. Aurora Kinase A expression predicts platinum-resistance and adverse outcome in high-grade serous ovarian carcinoma patients.

    PubMed

    Mignogna, Chiara; Staropoli, Nicoletta; Botta, Cirino; De Marco, Carmela; Rizzuto, Antonia; Morelli, Michele; Di Cello, Annalisa; Franco, Renato; Camastra, Caterina; Presta, Ivan; Malara, Natalia; Salvino, Angela; Tassone, Pierfrancesco; Tagliaferri, Pierosandro; Barni, Tullio; Donato, Giuseppe; Di Vito, Anna

    2016-01-01

    High-Grade Serous Ovarian Carcinoma (HGSOC) is the predominant histotype of epithelial ovarian cancer (EOC), characterized by advanced stage at diagnosis, frequent TP53 mutation, rapid progression, and high responsiveness to platinum-based-chemotherapy. To date, standard first-line-chemotherapy in advanced EOC includes platinum salts and paclitaxel with or without bevacizumab. The major prognostic factor is the response duration from the end of the platinum-based treatment (platinum-free interval) and about 10-0 % of EOC patients bear a platinum-refractory disease or develop early resistance (platinum-free interval shorter than 6 months). On these bases, a careful selection of patients who could benefit from chemotherapy is recommended to avoid unnecessary side effects and for a better disease outcome. In this retrospective study, an immunohistochemical evaluation of Aurora Kinase A (AURKA) was performed on 41 cases of HGSOC according to platinum-status. Taking into account the number and intensity of AURKA positive cells we built a predictive score able to discriminate with high accuracy platinum-sensitive patients from platinum-resistant patients (p < 0.001). Furthermore, we observed that AURKA overexpression correlates to worse overall survival (p = 0.001; HR 0.14). We here suggest AURKA as new effective tool to predict the biological behavior of HGSOC. Particularly, our results indicate that AURKA has a role both as predictor of platinum-resistance and as prognostic factor, that deserves further investigation in prospective clinical trials. Indeed, in the era of personalized medicine, AURKA could assist the clinicians in selecting the best treatment and represent, at the same time, a promising new therapeutic target in EOC treatment. PMID:27209210

  17. Platinum-ruthenium-palladium fuel cell electrocatalyst

    DOEpatents

    Gorer, Alexander

    2006-02-07

    A catalyst suitable for use in a fuel cell, especially as an anode catalyst, that contains platinum at a concentration that is between about 20 and about 60 atomic percent, ruthenium at a concentration that is between about 20 and about 60 atomic percent, palladium at a concentration that is between about 5 and about 45 atomic percent, and having an atomic ratio of platinum to ruthenium that is between about 0.7 and about 1.2. Alternatively, the catalyst may contain platinum at a concentration that is between about 25 and about 50 atomic percent, ruthenium at a concentration that is between about 25 and about 55 atomic percent, palladium at a concentration that is between about 5 and about 45 atomic percent, and having a difference between the concentrations of ruthenium and platinum that is no greater than about 20 atomic percent.

  18. Platinum-ruthenium-nickel fuel cell electrocatalyst

    DOEpatents

    Gorer, Alexander

    2005-07-26

    A catalyst suitable for use in a fuel cell, especially as an anode catalyst, that contains platinum, ruthenium, and nickel, wherein the nickel is at a concentration that is less than about 10 atomic percent.

  19. Platinum-Resistor Differential Temperature Sensor

    NASA Technical Reports Server (NTRS)

    Kolbly, R. B.; Britcliffe, M. J.

    1985-01-01

    Platinum resistance elements used in bridge circuit for measuring temperature difference between two flowing liquids. Temperature errors with circuit are less than 0.01 degrees C over range of 100 degrees C.

  20. Stabilizing platinum in phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Remick, R. J.

    1981-01-01

    The cathode of the phosphoric acid fuel cell uses a high surface area platinum catalyst supported on a carbon substrate. During operation, the small platinum crystallites sinter, causing loss in cell performance. A support was developed that stabilizes platinum in the high surface area condition by retarding or preventing the sintering process. The approach is to form etch pits in the carbon by oxidizing the carbon in the presence of a metal oxide catalyst, remove the metal oxide by an acid wash, and then deposit platinum in these pits. Results confirm the formation of etch pits in each of the three supports chosen for investigation: Vulcan XC-72R, Vulcan XC-72 that was graphized at 2500 C, and Shawinigan Acetylene Black.

  1. Stabilizing platinum in phosphoric acid fuel cells

    NASA Technical Reports Server (NTRS)

    Remick, R. J.

    1982-01-01

    Platinum sintering on phosphoric acid fuel cell cathodes is discussed. The cathode of the phosphoric acid fuel cell uses a high surface area platinum catalyst dispersed on a conductive carbon support to minimize both cathode polarization and fabrication costs. During operation, however, the active surface area of these electrodes decreases, which in turn leads to decreased cell performance. This loss of active surface area is a major factor in the degradation of fuel cell performance over time.

  2. Compatability of dispersion-strengthened platinum with resistojet propellants

    NASA Technical Reports Server (NTRS)

    Whalen, Margaret V.; Nathal, Michael V.

    1987-01-01

    Resistojets for the Space Station require long life and multipropellant capability. The choice of available materials to meet these requirements is limited. Dispersion-strengthened platinum was selected. Past results indicated that it should be suffieiently inert in candidate propellant environments and should be capable of operating at moderate temperatures for extended periods. A series of propellant compatibility tests was done with platinum strengthened with either yttria or zirconia. Data presented included the results of 1000-hr tests in CO2, H2, ammonia (NH3), N2, steam, hydrazine (N2H4), and methane (CH4); and 2000-hr tests in H2 and NH3. The platinum samples were tested at 1400 C in CO2, H2, NH3, N2, steam, and N2H4; at 500 C in CH4; and at 800 C in N2H4. The mass-loss results indicated material life, exptrapolated from experimental mass-loss data, in excess of 100 000 hr in all environments except steam and N2H4, where it was greater than or =45000 hr. Generally, on the basis of mass loss, there were no compatibility concerns in any of the environments considered. Optical and scanning electron microscopy were used to determine the effect of propellants on the material surface and to evaluate material stability.

  3. Antidiabetic Agents.

    ERIC Educational Resources Information Center

    Plummer, Nancy; Michael, Nancy, Ed.

    This module on antidiabetic agents is intended for use in inservice or continuing education programs for persons who administer medications in long-term care facilities. Instructor information, including teaching suggestions, and a listing of recommended audiovisual materials and their sources appear first. The module goal and objectives are then…

  4. HEPARAN SULFATE PROTEOGLYCAN-MEDIATED ENTRY PATHWAY FOR CHARGED TRI-PLATINUM COMPOUNDS. DIFFERENTIAL CELLULAR ACCUMULATION MECHANISMS FOR PLATINUM

    PubMed Central

    Silva, Heveline; Frézard, Frédéric; Peterson, Erica J.; Kabolizadeh, Peyman; Ryan, John J.; Farrell, Nicholas P.

    2012-01-01

    We examined the mechanism of accumulation of charged polynuclear platinum complexes (PPCs), based on analogy of polyarginine interactions with the cell surface heparan sulfate proteoglycan (HSPG) family of protein-linked glycosoaminoglycan polysaccharides (GAGs). GAGS such as heparan sulfate (HS) and chondroitin sulfate (CS) mediate the cellular entry of many charged molecules. Fluorescence microscopy and flow cytometry showed that PPCs, but not the neutral cisplatin or oxaliplatin, blocked the cellular entry of TAMRA-R9 (a nonarginine peptide, R9) coupled to the TAMRA fluorescent label 5-(and 6-)carboxytetramethylrhodamine) in Chinese Hamster Ovary (CHO), human colon carcinoma (HCT116), and osteosarcoma (SAOS-2) cells. Furthermore, detection of platinum accumulation in wt CHO, mutant CHO-pgsD-677 (lacking HS), and CHO-pgsA (lacking HS/CS) cells confirms that HSPG-mediated interactions are an important mechanism for PPC internalization, but not so for uncharged cisplatin and oxaliplatin. Endocytosis inhibitor studies show that macropinocytosis, a mechanism of cell entry for heparan sulfate GAGs and arginine-rich peptides, is important in the cellular accumulation of “non-covalent” TriplatinNC, and to a lesser degree, the covalently-binding BBR3464. Clathrin-mediated endocytosis, however, was not involved in either case. Overall the results suggest a new proteoglycan-mediated mechanism for cellular accumulation of PPCs not shared by cisplatin or oxaliplatin. The results have significant implications for rational design of platinum antitumor drugs with distinct biological profiles in comparison to the clinically-used agents as well as expanding the chemotypes for HS proteoglycan-dependent receptors. PMID:22494465

  5. Allergic reaction to platinum in silicone breast implants.

    PubMed

    Arepalli, Sambasiva R; Bezabeh, Shewit; Brown, S Lori

    2002-01-01

    Platinum is used as a catalyst in the manufacture of silicone breast implants. Because platinum is recognized as a potent sensitizer in certain circumstances, some have expressed concern that women with silicone breast implants are exposed to platinum, which is causing allergic reactions. We searched the literature for information on the level of platinum in breast implants and reports of sensitization that clearly related to platinum in women with breast implants. We found no published report with convincing evidence that platinum causes allergic reactions in women with breast implants or that women with breast implants are any more likely to have allergic reactions than women without breast implants. PMID:12627791

  6. Studies of n-butane conversion over silica-supported platinum, platinum-silver and platinum-copper catalysts

    SciTech Connect

    Gu, Junhua

    1992-06-09

    The present work was undertaken to elucidate effect of adding silver and copper to silica-supported platinum catalyst on the activity and selectivity in the n-butane reactions. At the conditions of this study n-butane underwent both hydrogenolysis and structural isomerization. The catalytic activity and selectivities between hydrogenolysis and isomerization and within hydrogenolysis were measured at temperature varying from 330 C to 370 C. For platinum-silver catalysts, at lower temperatures studied the catalytic activity per surface platinum atom (turnover frequency) remained constant at lower silver content (between 0 at. % and 30 at. %) and decreased with further increased silver loading, suggesting that low- index planes could be dominant in the hydrogenolysis of n-butane. Moreover, increasing silver content resulted in an enhancement of the selectivity of isomerization products relative to hydrogenolysis products. At the higher temperature studied, no suppression in catalytic activity was observed. It is postulated that surface structure could change due to the mobility of surface silver atoms, leading to surface silver atoms forming islands or going to the bulk, and leaving large portions of basal planes exposed with active platinum atoms. It is also suggested that the presence of inert silver atoms results in weakening of the H-surface bond. This results in increased mobility of hydrogen atoms on the surface and hence, higher reactivity with other adsorbed species. For platinum copper catalysts, the mixed ensembles could play an active role in the hydrogenolysis of n-butane.

  7. Biologically Inspired Phosphino Platinum Complexes

    SciTech Connect

    Jain, Avijita; Helm, Monte L.; Linehan, John C.; DuBois, Daniel L.; Shaw, Wendy J.

    2012-08-01

    Platinum complexes containing phosphino amino acid and amino acid ester ligands, built upon the PPhNR’2 platform, have been synthesized and characterized (PPhNR’2= [1,3-diaza]-5-phenyl phosphacyclohexane, R’=glycine or glycine ester). These complexes were characterized by 31P, 13C, 1H, 195Pt NMR spectroscopy and mass spectrometry. The X-ray crystal structure of one of the complexes, [PtCl2(PPhNGlyester 2)2], is also reported. These biologically inspired ligands have potential use in homogeneous catalysis, with special applications in chiral chemistry and water soluble chemistry. These complexes also provide a foundation upon which larger peptides can be attached, to allow the introduction of enzyme-like features onto small molecule catalysts. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  8. Platinum metals magmatic sulfide ores.

    PubMed

    Naldrett, A J; Duke, J M

    1980-06-27

    Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example. PMID:17796685

  9. Stripping voltammetric determination of palladium, platinum and rhodium in freshwater and sediment samples from South African water resources.

    PubMed

    van der Horst, C; Silwana, B; Iwuoha, E; Somerset, V

    2012-01-01

    Stripping voltammetry as technique has proved to be very useful in the analysis of heavy and other metal ions due to its excellent detection limits and its sensitivity in the presence of different metal species or interfering ions. Recent assessments of aquatic samples have shown increased levels of platinum group metals (PGMs) in aquatic ecosystems, caused by automobile exhaust emissions and mining activities. The development of an analytical sensor for the detection and characterisation of PGMs were investigated, since there is an ongoing need to find new sensing materials with suitable recognition elements that can respond selectively and reversibly to specific metal ions in environmental samples. The work reported shows the successful application of another mercury-free sensor electrode for the determination of platinum group metals in environmental samples. The work reported in this study entails the use of a glassy carbon electrode modified with a bismuth film for the determination of platinum (Pt(2+)), palladium (Pd(2+)) or rhodium (Rh(2+)) by means of adsorptive cathodic stripping voltammetry. Optimised experimental conditions included composition of the supporting electrolyte, complexing agent concentration, deposition potential, deposition time and instrumental voltammetry parameters for Pt(2+), Pd(2+) and Rh(2+) determination. Adsorptive differential pulse stripping voltammetric measurements for PGMs were performed in the presence of dimethylglyoxime (DMG) as complexing agent. The glassy carbon bismuth film electrode (GC/BiFE) employed in this study exhibit good and reproducible sensor characteristics. Application of GC/BiFE sensor exhibited well-defined peaks and highly linear behaviour for the stripping analysis of the PGMs in the concentration range between 0 and 3.5 μg/L. The detection limit of Pd, Pt and Rh was found to be 0.12 μg/L, 0.04 μg/L and 0.23 μg/L, respectively for the deposition times of 90 s (Pd) and 150 s (for both Pt and Rh). Good

  10. Combinations of platinums and selected phytochemicals as a means of overcoming resistance in ovarian cancer.

    PubMed

    Huq, Fazlul; Yu, Jun Q; Beale, Philip; Chan, Charles; Arzuman, Lalia; Nessa, Meher U; Mazumder, Mohammed E H

    2014-01-01

    Cancer sufferers are often found to use herbal products along with targeted therapy although not much information (whether beneficial or harmful) is available about the effects of such combinations. In this study, we investigated synergism from the combination of platinum drugs and a number of tumour-active phytochemicals including curcumin, epigallocatechin-3-gallate, thymoquinone, genistein, resveratrol, betulinic acid and ursolic acid in three human ovarian cancer cell lines A2780, A2780(cisR) and A2780(ZD0473R), as a function of concentration and the sequence of administration. Both the dose-effect curves and combination indices show that the binary combinations of platinum drugs with the phytochemicals exert concentration- and sequence-dependent synergism in the cell lines. Generally the degree of synergism is found to be greater in sequenced administration such as 0/2 h, 2/0 h, 0/4 h and 4/0 h than the bolus. The variation in the nature of the combined drug action from being highly synergistic to antagonistic with the change in sequence of administration clearly indicates that the action of one drug modulates that of the other (towards the induction or inhibition of apoptosis). We have also used sequenced combinations of platinum drugs and bortezomib (a proteasome inhibitor that prevents cisplatin-induced proteasomal degration of copper transporter CTR1) to enhance cellular platinum accumulation and the level of platinum-DNA binding especially in the resistant human ovarian tumour models. Proteomic studies to identify the key proteins associated with platinum resistance are ongoing. We have identified 59 proteins associated with platinum resistance in ovarian tumor models. PMID:24403514

  11. Epirubicin, Cisplatin, and Capecitabine for Primary Platinum-Resistant or Platinum-Refractory Epithelial Ovarian Cancer

    PubMed Central

    Sayal, Karen; Gounaris, Ioannis; Basu, Bristi; Freeman, Sue; Moyle, Penny; Hosking, Karen; Iddawela, Mahesh; Jimenez-Linan, Mercedes; Abraham, Jean; Brenton, James; Hatcher, Helen; Earl, Helena; Parkinson, Christine

    2015-01-01

    Objective Primary platinum-resistant epithelial ovarian cancer (EOC) is an area of unmet medical need. There is limited evidence from small studies that platinum-based combinations can overcome “resistance” in a proportion of patients. We investigated the efficacy and toxicity of platinum-based combination chemotherapy in the platinum-resistant and platinum-refractory setting. Methods Epirubicin, cisplatin, and capecitabine (ECX) combination chemotherapy was used at our institution for the treatment of relapsed EOC. From the institutional database, we identified all patients with primary platinum-refractory or platinum-resistant relapse treated with ECX as second-line therapy between 2001 and 2012. We extracted demographic, clinical, treatment, and toxicity data and outcomes. We used logistic and Cox regression models to identify predictors of response and survival respectively. Results Thirty-four 34 patients (8 refractory, 26 resistant) were treated with ECX. Response Evaluation Criteria In Solid Tumors (RECIST) response rate was 45%, median progression-free survival (PFS) was 6.4 months, and overall survival (OS) was 10.6 months. Platinum-resistant patients had better outcomes than did platinum-refractory patients (response rate, 54% vs 0%, P = 0.047; PFS 7.2 vs 1.8 months, P < 0.0001; OS 14.4 vs 3 months, P < 0.001). In regression models, time to progression after first-line treatment and platinum-refractory status were the strongest predictors of response and PFS or OS, respectively. Patients with time to progression after first-line treatment longer than 3 months showed PFS and OS of 7.9 and 14.7 months, respectively. Toxicity was manageable, with only 13% of cycles administered at reduced doses. Conclusions Epirubicin, cisplatin, and capecitabine seems to be active in platinum-resistant relapsed EOC with manageable toxicity. Further prospective investigation of platinum-anthracycline combinations is warranted in patients who relapse 3 to 6 months after

  12. Sum Frequency Generation Studies of Hydrogenation Reactions on Platinum Nanoparticles

    SciTech Connect

    Krier, James M.

    2013-08-31

    Sum Frequency Generation (SFG) vibrational spectroscopy is used to characterize intermediate species of hydrogenation reactions on the surface of platinum nanoparticle catalysts. In contrast to other spectroscopy techniques which operate in ultra-high vacuum or probe surface species after reaction, SFG collects information under normal conditions as the reaction is taking place. Several systems have been studied previously using SFG on single crystals, notably alkene hydrogenation on Pt(111). In this thesis, many aspects of SFG experiments on colloidal nanoparticles are explored for the first time. To address spectral interference by the capping agent (PVP), three procedures are proposed: UV cleaning, H2 induced disordering and calcination (core-shell nanoparticles). UV cleaning and calcination physically destroy organic capping while disordering reduces SFG signal through a reversible structural change by PVP.

  13. The Role of Organic Capping Layers of Platinum Nanoparticles in Catalytic Activity of CO Oxidation

    SciTech Connect

    Park, Jeong Y.; Aliaga, Cesar; Renzas, J. Russell; Lee, Hyunjoo; Somorjai, Gabor A.

    2008-12-17

    We report the catalytic activity of colloid platinum nanoparticles synthesized with different organic capping layers. On the molecular scale, the porous organic layers have open spaces that permit the reactant and product molecules to reach the metal surface. We carried out CO oxidation on several platinum nanoparticle systems capped with various organic molecules to investigate the role of the capping agent on catalytic activity. Platinum colloid nanoparticles with four types of capping layer have been used: TTAB (Tetradecyltrimethylammonium Bromide), HDA (hexadecylamine), HDT (hexadecylthiol), and PVP (poly(vinylpyrrolidone)). The reactivity of the Pt nanoparticles varied by 30%, with higher activity on TTAB coated nanoparticles and lower activity on HDT, while the activation energy remained between 27-28 kcal/mol. In separate experiments, the organic capping layers were partially removed using ultraviolet light-ozone generation techniques, which resulted in increased catalytic activity due to the removal of some of the organic layers. These results indicate that the nature of chemical bonding between organic capping layers and nanoparticle surfaces plays a role in determining the catalytic activity of platinum colloid nanoparticles for carbon monoxide oxidation.

  14. Nuclear survivin expression is a positive prognostic factor in taxane-platinum-treated ovarian cancer patients

    PubMed Central

    2011-01-01

    Background Survivin is an inhibitor of apoptosis and a regulator of mitotic progression. TP53 protein is a negative transcriptional regulator of survivin. The aim of our study was to evaluate the clinical significance of survivin expression in advanced stages ovarian cancer with respect to the TP53 status. Methods Survivin and TP53 expression was evaluated immunohistochemically in 435 archival samples of ovarian carcinomas (244 patients were treated with platinum/cyclophosphamide-PC/PAC; 191-with taxane-platinum (TP) agents). Univariate and multivariate statistical analyses were performed in patients groups divided according to the administered chemotherapeutic regimen, and in subgroups with and without TP53 accumulation (TP53+ and TP53-, respectively). Results Nuclear and cytoplasmic survivin expression was observed in 92% and 74% of the carcinomas, respectively. In patients treated with TP, high nuclear survivin expression decreased the risk of disease recurrence and death, and increased the probability of high platinum sensitivity (p < 0.01), but only in the TP53(+) group, and not in the TP53(-) group. Conclusions It appears that TP53 status determines the clinical importance of nuclear survivin expression in taxane-platinum treated ovarian cancer patients. PMID:22075440

  15. Effects triggered by platinum nanoparticles on primary keratinocytes

    PubMed Central

    Konieczny, Piotr; Goralczyk, Anna Grazyna; Szmyd, Radoslaw; Skalniak, Lukasz; Koziel, Joanna; Filon, Francesca Larese; Crosera, Matteo; Cierniak, Agnieszka; Zuba-Surma, Ewa K; Borowczyk, Julia; Laczna, Eliza; Drukala, Justyna; Pyza, Elzbieta; Semik, Danuta; Woznicka, Olga; Klein, Andrzej; Jura, Jolanta

    2013-01-01

    The platinum (Pt)-group elements (PGEs) represent a new kind of environmental pollutant and a new hazard for human health. Since their introduction as vehicle-exhaust catalysts, their emissions into the environment have grown considerably compared with their low natural concentration in the earth crust. PGE emissions from vehicle catalysts can be also in the form of nanometer-sized particles (Pt nanoparticles [PtNPs]). These elements, both in their metallic form or as ions solubilized in biological media, are now recognized as potent allergens and sensitizers. Human skin is always exposed to toxic particles; therefore, in the present study we addressed the question of whether polyvinylpyrrolidone-coated PtNPs may have any negative effects on skin cells, including predominantly epidermal keratinocytes. In this study, PtNPs of two sizes were used: 5.8 nm and 57 nm, in concentrations of 6.25, 12.5, and 25 μg/mL. Both types of NPs were protected with polyvinylpyrrolidone. Primary keratinocytes were treated for 24 and 48 hours, then cytotoxicity, genotoxicity, morphology, metabolic activity, and changes in the activation of signaling pathways were investigated in PtNP-treated cells. We found that PtNPs trigger toxic effects on primary keratinocytes, decreasing cell metabolism, but these changes have no effects on cell viability or migration. Moreover, smaller NPs exhibited more deleterious effect on DNA stability than the big ones. Analyzing activation of caspases, we found changes in activity of caspase 9 and caspase 3/7 triggered mainly by smaller NPs. Changes were not so significant in the case of larger nanoparticles. Importantly, we found that PtNPs have antibacterial properties, as is the case with silver NPs (AgNPs). In comparison to our previous study regarding the effects of AgNPs on cell biology, we found that PtNPs do not exhibit such deleterious effects on primary keratinocytes as AgNPs and that they also can be used as potential antibacterial agents

  16. Surface decorated platinum carbonyl clusters

    NASA Astrophysics Data System (ADS)

    Ciabatti, Iacopo; Femoni, Cristina; Iapalucci, Maria Carmela; Longoni, Giuliano; Zacchini, Stefano; Zarra, Salvatore

    2012-06-01

    Four molecular Pt-carbonyl clusters decorated by Cd-Br fragments, i.e., [Pt13(CO)12{Cd5(μ-Br)5Br2(dmf)3}2]2- (1), [Pt19(CO)17{Cd5(μ-Br)5Br3(Me2CO)2}{Cd5(μ-Br)5Br(Me2CO)4}]2- (2), [H2Pt26(CO)20(CdBr)12]8- (3) and [H4Pt26(CO)20(CdBr)12(PtBr)x]6- (4) (x = 0-2), have been obtained from the reactions between [Pt3n(CO)6n]2- (n = 2-6) and CdBr2.H2O in dmf at 120 °C. The structures of these molecular clusters with diameters of 1.5-2 nm have been determined by X-ray crystallography. Both 1 and 2 are composed of icosahedral or bis-icosahedral Pt-CO cores decorated on the surface by Cd-Br motifs, whereas 3 and 4 display a cubic close packed Pt26Cd12 metal frame decorated by CO and Br ligands. An oversimplified and unifying approach to interpret the electron count of these surface decorated platinum carbonyl clusters is suggested, and extended to other low-valent organometallic clusters and Au-thiolate nanoclusters.Four molecular Pt-carbonyl clusters decorated by Cd-Br fragments, i.e., [Pt13(CO)12{Cd5(μ-Br)5Br2(dmf)3}2]2- (1), [Pt19(CO)17{Cd5(μ-Br)5Br3(Me2CO)2}{Cd5(μ-Br)5Br(Me2CO)4}]2- (2), [H2Pt26(CO)20(CdBr)12]8- (3) and [H4Pt26(CO)20(CdBr)12(PtBr)x]6- (4) (x = 0-2), have been obtained from the reactions between [Pt3n(CO)6n]2- (n = 2-6) and CdBr2.H2O in dmf at 120 °C. The structures of these molecular clusters with diameters of 1.5-2 nm have been determined by X-ray crystallography. Both 1 and 2 are composed of icosahedral or bis-icosahedral Pt-CO cores decorated on the surface by Cd-Br motifs, whereas 3 and 4 display a cubic close packed Pt26Cd12 metal frame decorated by CO and Br ligands. An oversimplified and unifying approach to interpret the electron count of these surface decorated platinum carbonyl clusters is suggested, and extended to other low-valent organometallic clusters and Au-thiolate nanoclusters. CCDC 867747 and 867748. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c2nr30400g

  17. Autonomous movement of platinum-loaded stomatocytes.

    PubMed

    Wilson, Daniela A; Nolte, Roeland J M; van Hest, Jan C M

    2012-04-01

    Polymer stomatocytes are bowl-shaped structures of nanosize dimensions formed by the controlled deformation of polymer vesicles. The stable nanocavity and strict control of the opening are ideal for the physical entrapment of nanoparticles which, when catalytically active, can turn the stomatocyte morphology into a nanoreactor. Herein we report an approach to generate autonomous movement of the polymer stomatocytes by selectively entrapping catalytically active platinum nanoparticles within their nanocavities and subsequently using catalysis as a driving force for movement. Hydrogen peroxide is free to access the inner stomatocyte cavity, where it is decomposed by the active catalyst (the entrapped platinum nanoparticles) into oxygen and water. This generates a rapid discharge, which induces thrust and directional movement. The design of the platinum-loaded stomatocytes resembles a miniature monopropellant rocket engine, in which the controlled opening of the stomatocytes directs the expulsion of the decomposition products away from the reaction chamber (inner stomatocyte cavity). PMID:22437710

  18. Further studies on the synthesis of finely divided platinum

    SciTech Connect

    Turkevich, J.; Miner, R.S. Jr.; Babenkova, L.

    1986-09-25

    An investigation was made of the effect of pH and of starting platinum complexes on the synthesis of monodisperse platinum particles by citrate reduction. The antitumor drug cis-platin does not readily produce colloidal particles, and these lack activity for hydrogen peroxide decomposition. The growth of platinum particles by both citrate reduction and hydrogen gas treatment was also studied.

  19. Platinum Publications, January 1–March 31, 2016 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  20. Platinum Publications, October 1–29, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  1. Platinum Publications, July 31–September 30, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  2. Platinum Publications, June 26–July 30, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  3. Platinum Publications, October 30–December 31, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  4. Platinum Publications, November 27, 2014 – February 26, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  5. Platinum Publications, October 30 – November 26, 2014 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  6. Platinum Publications, February 27 – March 26, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  7. Platinum Publications as of May 29, 2014 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  8. Platinum Publications as of June 25, 2014 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  9. Platinum Publications as of March 6, 2014 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  10. Platinum Publications as of September 25, 2014 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  11. Platinum Publications, March 27 – April 30, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  12. Platinum Publications, February 27 – March 26, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  13. Platinum Publications, October 30 – November 26, 2014 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  14. Platinum Publications, July 31–September 30, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  15. Platinum Publications, June 26–July 30, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  16. Platinum Publications, July 1–July 28, 2016 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  17. Platinum Publications, September 26 – October 29, 2014 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  18. Platinum Publications as of April 30, 2014 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  19. Platinum Publications, October 30–December 31, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  20. Platinum Publications, September 26 – October 29, 2014 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  1. Platinum Publications, April 1–May 27, 2016 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  2. Platinum Publications, January 1–March 31, 2016 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  3. Platinum Publications as of December 3, 2013 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 21 prestigious science journals. This list represents new publications generated from PubMed as of the date shown above. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  4. Platinum Publications, June 1–June 30, 2016 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  5. Platinum Publications, May 1 – June 25, 2015 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed. Articles designated as Platinum Highlights are noteworthy articles selected by Dr. Craig Reynolds, associate director, National Cancer Institute, from among the most recently published Platinum Publications.

  6. Amrubicin Monotherapy for Patients with Platinum-Refractory Gastroenteropancreatic Neuroendocrine Carcinoma.

    PubMed

    Ando, Takayuki; Hosokawa, Ayumu; Yoshita, Hiroki; Ueda, Akira; Kajiura, Shinya; Mihara, Hiroshi; Nanjo, Sohachi; Fujinami, Haruka; Nishikawa, Jun; Ogawa, Kohei; Nakajima, Takahiko; Imura, Johji; Sugiyama, Toshiro

    2015-01-01

    Objective. Patients with gastroenteropancreatic neuroendocrine carcinoma (NEC) have a poor prognosis. Platinum-based combination chemotherapy is commonly used as first-line treatment; however, the role of salvage chemotherapy remains unknown. This study aimed to analyze the efficacy and safety of amrubicin monotherapy in patients with platinum-refractory gastroenteropancreatic NEC. Methods. Among 22 patients with advanced gastroenteropancreatic NEC, 10 received amrubicin monotherapy between September 2007 and May 2014 after failure of platinum-based chemotherapy. The efficacy and toxicity of the treatment were analyzed retrospectively. Results. Eight males and two females (median age, 67 years (range, 52-78)) received platinum-based chemotherapy, including cisplatin plus irinotecan (n = 7, 70%), cisplatin plus etoposide (n = 2, 20%), and carboplatin plus etoposide (n = 1, 10%) before amrubicin therapy. Median progression-free survival and overall survival after amrubicin therapy were 2.6 and 5.0 months, respectively. Two patients had partial response (20% response rate), and their PFS were 6.2 months and 6.3 months, respectively. Furthermore, NEC with response for amrubicin had characteristics with a high Ki-67 index and receipt of prior chemotherapy with cisplatin and irinotecan. Grade 3-4 neutropenia and anemia were observed in four and five patients, respectively. Conclusion. Amrubicin monotherapy appears to be potentially active and well-tolerated for platinum-refractory gastroenteropancreatic NEC. PMID:26199623

  7. Nonenzymatic glucose detection using mesoporous platinum.

    PubMed

    Park, Sejin; Chung, Taek Dong; Kim, Hee Chan

    2003-07-01

    Roughness of nanoscopic dimensions can be used to selectively enhance the faradaic current of a sluggish reaction. Using this principle, we constructed mesoporous structures on the surfaces of pure platinum electrodes responding even more sensitively to glucose than to common interfering species, such as L-ascorbic acid and 4-acetamidophenol. Good sensitivities, as high as 9.6 microA cm(-2) mM(-1), were reproducibly observed in the presence of high concentration of chloride ion. The selectivities, sensitivities, and stabilities determined experimentally have demonstrated the potential of mesoporous platinum as a novel candidate for nonenzymatic glucose sensors. PMID:12964749

  8. Determination of gold and platinum traces in biological materials as a part of a multi-element radiochemical activation analysis system.

    PubMed

    Tjioe, P S; Volkers, K J; Kroon, J J; de Goeij, J J; The, S K

    1984-01-01

    For the analysis of human tissues for traces of gold and platinum--being used as constituents of therapeutic agents--a radiochemical neutron activation method has been developed. The radiochemical separation involves the selective removal of radioactive gold--formed by the reaction 197Au (n, gamma)198Au and the reaction 198Pt (n, gamma) 199Pt ---- 199Au --as small metallic nuggets . The determination of gold and platinum is carried out as a part of an automated multi-element radiochemical separation scheme, allowing the determination of about 20 additional trace elements, and thus giving the possibility to study interelement relations. The analytical characteristics of the determination are evaluated. Gold and platinum levels measured in Bowen's Kale, NBS Bovine Liver and NBS Orchard Leaves are presented. Values are shown for gold, platinum, and 20 other trace elements in various healthy and cancerous tissues from patients treated with cis-platin. (Cis-Diamminedichloroplatinum II). PMID:6724783

  9. MRI-detectable polymeric micelles incorporating platinum anticancer drugs enhance survival in an advanced hepatocellular carcinoma model

    PubMed Central

    Vinh, Nguyen Quoc; Naka, Shigeyuki; Cabral, Horacio; Murayama, Hiroyuki; Kaida, Sachiko; Kataoka, Kazunori; Morikawa, Shigehiro; Tani, Tohru

    2015-01-01

    Hepatocellular carcinoma (HCC) is one of the most intractable and lethal cancers; most cases are diagnosed at advanced stages with underlying liver dysfunction and are frequently resistant to conventional chemotherapy and radiotherapy. The development of tumor-targeting systems may improve treatment outcomes. Nanomedicine platforms are of particular interest for enhancing chemotherapeutic efficiency, and they include polymeric micelles, which enable targeting of multiple drugs to solid tumors, including imaging and therapeutic agents. This allows concurrent diagnosis, targeting strategy validation, and efficacy assessment. We used polymeric micelles containing the T1-weighted magnetic resonance imaging contrast agent gadolinium-diethylenetriaminpentaacetic acid (Gd-DTPA) and the parent complex of the anticancer drug oxaliplatin [(1,2-diaminocyclohexane)platinum(II) (DACHPt)] for simultaneous imaging and therapy in an orthotopic rat model of HCC. The Gd-DTPA/DACHPt-loaded micelles were injected into the hepatic artery, and magnetic resonance imaging performance and antitumor activity against HCC, as well as adverse drug reactions were assessed. After a single administration, the micelles achieved strong and specific tumor contrast enhancement, induced high levels of tumor apoptosis, and significantly suppressed tumor size and growth. Moreover, the micelles did not induce severe adverse reactions and significantly improved survival outcomes in comparison to oxaliplatin or saline controls. Our results suggest that Gd-DTPA/DACHPt-loaded micelles are a promising approach for effective diagnosis and treatment of advanced HCC. PMID:26203241

  10. MRI-detectable polymeric micelles incorporating platinum anticancer drugs enhance survival in an advanced hepatocellular carcinoma model.

    PubMed

    Vinh, Nguyen Quoc; Naka, Shigeyuki; Cabral, Horacio; Murayama, Hiroyuki; Kaida, Sachiko; Kataoka, Kazunori; Morikawa, Shigehiro; Tani, Tohru

    2015-01-01

    Hepatocellular carcinoma (HCC) is one of the most intractable and lethal cancers; most cases are diagnosed at advanced stages with underlying liver dysfunction and are frequently resistant to conventional chemotherapy and radiotherapy. The development of tumor-targeting systems may improve treatment outcomes. Nanomedicine platforms are of particular interest for enhancing chemotherapeutic efficiency, and they include polymeric micelles, which enable targeting of multiple drugs to solid tumors, including imaging and therapeutic agents. This allows concurrent diagnosis, targeting strategy validation, and efficacy assessment. We used polymeric micelles containing the T1-weighted magnetic resonance imaging contrast agent gadolinium-diethylenetriaminpentaacetic acid (Gd-DTPA) and the parent complex of the anticancer drug oxaliplatin [(1,2-diaminocyclohexane)platinum(II) (DACHPt)] for simultaneous imaging and therapy in an orthotopic rat model of HCC. The Gd-DTPA/DACHPt-loaded micelles were injected into the hepatic artery, and magnetic resonance imaging performance and antitumor activity against HCC, as well as adverse drug reactions were assessed. After a single administration, the micelles achieved strong and specific tumor contrast enhancement, induced high levels of tumor apoptosis, and significantly suppressed tumor size and growth. Moreover, the micelles did not induce severe adverse reactions and significantly improved survival outcomes in comparison to oxaliplatin or saline controls. Our results suggest that Gd-DTPA/DACHPt-loaded micelles are a promising approach for effective diagnosis and treatment of advanced HCC. PMID:26203241

  11. Luminescent Cyclometalated Platinum and Palladium Complexes with Novel Photophysical Properties

    NASA Astrophysics Data System (ADS)

    Turner, Eric

    Organic light emitting diodes (OLEDs) is a rapidly emerging technology based on organic thin film semiconductors. Recently, there has been substantial investment in their use in displays. In less than a decade, OLEDs have grown from a promising academic curiosity into a multi-billion dollar global industry. At the heart of an OLED are emissive molecules that generate light in response to electrical stimulation. Ideal emitters are efficient, compatible with existing materials, long lived, and produce light predominantly at useful wavelengths. Developing an understanding of the photophysical processes that dictate the luminescent properties of emissive materials is vital to their continued development. Chapter 1 and Chapter 2 provide an introduction to the topics presented and the laboratory methods used to explore them. Chapter 3 discusses a series of tridentate platinum complexes. A synthetic method utilizing microwave irradiation was explored, as well as a study of the effects ligand structure had on the excited state properties. Results and techniques developed in this endeavor were used as a foundation for the work undertaken in later chapters. Chapter 4 introduces a series of tetradentate platinum complexes that share a phenoxy-pyridyl (popy) motif. The new molecular design improved efficiency through increased rigidity and modification of the excited state properties. This class of platinum complexes were markedly more efficient than those presented in Chapter 3, and devices employing a green emitting complex of the series achieved nearly 100% electron-to-photon conversion efficiency in an OLED device. Chapter 5 adapts the ligand structure developed in Chapter 4 to palladium. The resulting complexes exceed reported efficiencies of palladium complexes by an order of magnitude. This chapter also provides the first report of a palladium complex as an emitter in an OLED device. Chapter 6 discusses the continuation of development efforts to include carbazolyl

  12. Say No to DMSO: Dimethylsulfoxide Inactivates Cisplatin, Carboplatin and Other Platinum Complexes

    PubMed Central

    Hall, Matthew D.; Telma, Katherine A.; Chang, Ki-Eun; Lee, Tobie D.; Madigan, James P.; Lloyd, John R.; Goldlust, Ian S.; Hoeschele, James D.; Gottesman, Michael M.

    2014-01-01

    The platinum drugs cisplatin, carboplatin and oxaliplatin are highly utilized in the clinic and as a consequence are extensively studied in the laboratory setting. In this study, we examined the literature and found a significant number of studies (11 - 34%) in prominent cancer journals utilizing cisplatin dissolved in dimethylsulfoxide (DMSO). However, dissolving cisplatin in DMSO for laboratory-based studies results in ligand displacement and changes the structure of the complex. We examined the effect of DMSO on platinum complexes, including cisplatin, carboplatin and oxaliplatin, finding that DMSO reacted with the complexes, inhibited their cytotoxicity and their ability to initiate cell death. These results render a substantial portion of the literature on cisplatin uninterpretable. Raising awareness of this significant issue in the cancer biology community is critical, and we make recommendations on appropriate solvation of platinum drugs for research. PMID:24812268

  13. Method for in-situ restoration of platinum resistance thermometer calibration

    SciTech Connect

    Carroll, R.M.

    1989-01-03

    A method is described for the in situ restoration of a platinum resistance thermometer, which has become decalibrated due to oxide surface film formation and/or strain-related damage, to a stress-free calibration condition wherein the thermometer includes a platinum resistor sensing element whose resistance varies with the temperature of the element in accordance with a known relationship. The method consists of: passing a controlled dc current through the platinum resistor sensing element, the current having a magnitude sufficient to raise the temperature of the element to its oxide decomposition and annealing temperature. The current is maintained for a heating period sufficient to restore the element to an oxide free surface and stress-free calibration condition.

  14. Significance of water solubility in the gastrointestinal absorption of trans-bis(n-valerato)(1R,2R-cyclohexanediamine)(oxalato)platinum(IV), an orally active antitumor platinum complex, and its analogs.

    PubMed

    Kizu, R; Nakanishi, T; Yamamoto, S; Hayakawa, K; Matsuzawa, A; Eriguchi, M; Takeda, Y; Akiyama, N; Kidani, Y

    1998-02-01

    Trans-bis(n-valerato)(1R,2R-cyclohexanediamine)(oxalato++ +)platinum(IV) (C5-OHP) is an orally active platinum complex we prepared. The gastrointestinal absorption of C5-OHP was examined in rats and compared with those of C5-OHP analogs which have a general formula of trans-bis(n-OCOCnH2n+1)(1R,2R-cyclohexanediamine)(oxalato )platinum(IV) as well as C5-OHP. The complexes did not show significant differences in pharmacokinetic behavior after i.v. injection. Plasma platinum level after a single oral administration at a dose was higher for a complex with higher water solubility. The intestinal absorption rate measured by an in situ recirculating perfusion technique was higher for a complex with higher lipophilicity. These results indicate that the water solubility is a more dominant factor than the lipophilicity in the gastrointestinal absorption of the complexes. Then, the effects of surfactants and alpha-cyclodextrin (alpha-CD) on the solubility of C5-OHP was studied. Among the agents tested, alpha-CD showed the highest effect in increasing the solubility. Administration of C5-OHP together with alpha-CD gave approximately three times higher plasma platinum levels than administration of C5-OHP alone. Water solubility was found to be a dominant factor in the gastrointestinal absorption of C5-OHP and its analogs. PMID:9510503

  15. Carbon monoxide tolerant electrocatalyst with low platinum loading and a process for its preparation

    DOEpatents

    Adzic, Radoslav; Brankovic, Stanko; Wang, Jia

    2003-12-30

    An electrocatalyst is provided for use in a fuel cell that has low platinum loading and a high tolerance to carbon monoxide poisoning. The fuel cell anode includes an electrocatalyst that has a conductive support material, ruthenium nanoparticles reduced in H.sub.2 and a Group VIII noble metal in an amount of between about 0.1 and 25 wt % of the ruthenium nanoparticles, preferably between about 0.5 and 15 wt %. The preferred Group VIII noble metal is platinum. In one embodiment, the anode can also have a perfluorinated polymer membrane on its surface.

  16. Primary malignant mediastinal germ cell tumours: improved prognosis with platinum-based chemotherapy and surgery.

    PubMed Central

    Childs, W. J.; Goldstraw, P.; Nicholls, J. E.; Dearnaley, D. P.; Horwich, A.

    1993-01-01

    A retrospective analysis was performed of 18 patients with primary malignant germ cell tumours of the mediastinum treated with platinum-based chemotherapy between 1977 and 1990. All seven patients with pure seminoma were treated initially with chemotherapy and four of these patients received additional mediastinal radiotherapy. Only one patient relapsed; his initial therapy had included radiotherapy and single-agent carboplatin and he was successfully salvaged with combination chemotherapy. With a follow-up of 11 to 117 months (median 41 months) all seven patients with seminoma remain alive and disease free giving an overall survival of 100%. Eleven patients had malignant non seminoma; following chemotherapy eight of these had elective surgical resection of residual mediastinal masses. Complete remission was achieved in nine (82%) patients, however, one of these patients died from bleomycin pneumonitis. With a follow-up of 12 to 113 months (median 55 months) eight of 11 (73%) patients with malignant mediastinal teratoma remain alive and disease free. PMID:8494705

  17. Chronology of platinum accumulation in an urban lake

    NASA Astrophysics Data System (ADS)

    Rauch, S.; Hermond, H. F.; Ravizza, G.; Morrison, G. M.

    2003-05-01

    Concern has recently emerged over the release of platinum from automobile catalysts and increasing environmental concentrations. The history of platinum deposition is followed through the natural incorporation of pollutants into the sediment record of the Upper Mystic Lake. Platinum was determined by ICP-MS in dated sediments. Platinum concentration remained relatively constant until the mid-1970s when Pt-containing catalysts were introduced in the US. After the introduction of catalysts, platinum concentration increased significantly, with an average deposition rate of 5.4 μg m^{-2} year^{-1} after 1990.

  18. Use of platinum electrodes for the electrochemical detection of bacteria

    NASA Technical Reports Server (NTRS)

    Wilkins, J. R.

    1978-01-01

    Platinum electrodes with surface area ratios of four to one were used to detect and enumerate a variety of gram-positive and gram-negative organisms. Linear relationships were established between inoculum size and detection time. End points for platinum electrodes were similar to those obtained with a platinum-reference electrode combination. Shape of the overall response curves and length of detection times for gram-positive organisms were markedly different than those for the majority of gram-negative species. Platinum electrodes are better than the platinum-reference electrode combination because of cost, ease of handling, and clearer definition of the end point.

  19. DNA polymerase η modulates replication fork progression and DNA damage responses in platinum-treated human cells

    NASA Astrophysics Data System (ADS)

    Sokol, Anna M.; Cruet-Hennequart, Séverine; Pasero, Philippe; Carty, Michael P.

    2013-11-01

    Human cells lacking DNA polymerase η (polη) are sensitive to platinum-based cancer chemotherapeutic agents. Using DNA combing to directly investigate the role of polη in bypass of platinum-induced DNA lesions in vivo, we demonstrate that nascent DNA strands are up to 39% shorter in human cells lacking polη than in cells expressing polη. This provides the first direct evidence that polη modulates replication fork progression in vivo following cisplatin and carboplatin treatment. Severe replication inhibition in individual platinum-treated polη-deficient cells correlates with enhanced phosphorylation of the RPA2 subunit of replication protein A on serines 4 and 8, as determined using EdU labelling and immunofluorescence, consistent with formation of DNA strand breaks at arrested forks in the absence of polη. Polη-mediated bypass of platinum-induced DNA lesions may therefore represent one mechanism by which cancer cells can tolerate platinum-based chemotherapy.

  20. Undoped and boron doped diamond nanoparticles as platinum and platinum-ruthenium catalyst support for direct methanol fuel cell application

    NASA Astrophysics Data System (ADS)

    La Torre Riveros, Lyda

    Nanoparticular diamond is a promising material that can be used as a robust and chemically stable catalytic support. It has been studied and characterized physically and electrochemically, in its powder and thin film forms. This thesis work intends to demonstrate that undoped diamond nanoparticles (DNPs) and boron-doped diamond nanoparticles (BDDNPs) can be used as an electrode and a catalytic support material for platinum and ruthenium catalysts. The electrochemical properties of diamond nanoparticle electrodes, fabricated using the ink paste method, were investigated. As an initial step, we carried out chemical purification of commercially available undoped DNPs by refluxing in aqueous HNO3 as well as of BDDNPs which were doped through a collaborative work with the University of Missouri. The purified material was characterized by spectroscopic and surface science techniques. The reversibility of reactions such as ferricyanide/ferrocyanide (Fe(CN) 63-/Fe(CN)64-) and hexaamineruthenium (III) chloride complexes as redox probes were evaluated by cyclic voltammetry at the undoped DNPs and BDDNPs surface. These redox probes showed limited peak currents and presented linear relationships between current (i) and the square root of the potential scan rate (v1/2). However, compared to conventional electrodes, the peak currents were smaller. BDDNPs show an improvement in charge transfer currents when compared to undoped DNPs. Platinum and ruthenium nanoparticles were chemically deposited on undoped DNPs and BDDNPs through the use of the excess of a mild reducing agent such NaBH4. In order to improve the nanoparticle dispersion sodium dodecyl benzene sulfonate (SDBS), a surfactant agent, was used. Percentages of platinum and ruthenium metals were varied as well as the stoichiometric amount of the reducing agent to determine adequate parameters for optimum performance in methanol oxidation. Both before and after the reducing process the samples were characterized by scanning

  1. The effectiveness and cost-effectiveness of erythropoiesis-stimulating agents (epoetin and darbepoetin) for treating cancer treatment-induced anaemia (including review of technology appraisal no. 142): a systematic review and economic model.

    PubMed Central

    Crathorne, Louise; Huxley, Nicola; Haasova, Marcela; Snowsill, Tristan; Jones-Hughes, Tracey; Hoyle, Martin; Briscoe, Simon; Coelho, Helen; Long, Linda; Medina-Lara, Antonieta; Mujica-Mota, Ruben; Napier, Mark; Hyde, Chris

    2016-01-01

    BACKGROUND Anaemia is a common side effect of cancer treatments and can lead to a reduction in quality of life. Erythropoiesis-stimulating agents (ESAs) are licensed for use in conjunction with red blood cell transfusions to improve cancer treatment-induced anaemia (CIA). OBJECTIVE To investigate the effectiveness and cost-effectiveness of ESAs in anaemia associated with cancer treatment (specifically chemotherapy). DATA SOURCES The following databases were searched from 2004 to 2013: The Cochrane Library, MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, Web of Science, Cumulative Index to Nursing and Allied Health Literature, British Nursing Index, Health Management Information Consortium, Current Controlled Trials and ClinicalTrials.gov. The US Food and Drug Administration and European Medicines Agency websites were also searched. Bibliographies of included papers were scrutinised for further potentially includable studies. REVIEW METHODS The clinical effectiveness review followed principles published by the NHS Centre for Reviews and Dissemination. Randomised controlled trials (RCTs), or systematic reviews of RCTs, of ESAs (epoetin or darbepoetin) for treating people with CIA were eligible for inclusion in the review. Comparators were best supportive care, placebo or other ESAs. Anaemia- and malignancy-related outcomes, health-related quality of life (HRQoL) and adverse events (AEs) were evaluated. When appropriate, data were pooled using meta-analysis. An empirical health economic model was developed comparing ESA treatment with no ESA treatment. The model comprised two components: one evaluating short-term costs and quality-adjusted life-years (QALYs) (while patients are anaemic) and one evaluating long-term QALYs. Costs and benefits were discounted at 3.5% per annum. Probabilistic and univariate deterministic sensitivity analyses were performed. RESULTS Of 1457 titles and abstracts screened, 23 studies assessing ESAs within their licensed

  2. Hydroxypyridonate chelating agents

    DOEpatents

    Raymond, Kenneth N.; Scarrow, Robert C.; White, David L.

    1987-01-01

    Chelating agents having 1-hydroxy-2-pyridinone (HOPO) and related moieties incorporated within their structures, including polydentate HOPO-substituted polyamines such as spermidine and spermine, and HOPO-substituted desferrioxamine. The chelating agents are useful in selectively removing certain cations from solution, and are particularly useful as ferric ion and actinide chelators. Novel syntheses of the chelating agents are provided.

  3. Platinum-based drugs: past, present and future.

    PubMed

    Dilruba, Shahana; Kalayda, Ganna V

    2016-06-01

    Platinum-based drugs cisplatin, carboplatin and oxaliplatin are widely used in the therapy of human neoplasms. Their clinical success is, however, limited due to severe side effects and intrinsic or acquired resistance to the treatment. Much effort has been put into the development of new platinum anticancer complexes, but none of them has reached worldwide clinical application so far. Nedaplatin, lobaplatin and heptaplatin received only regional approval. Some new platinum complexes and platinum drug formulations are undergoing clinical trials. Here, we review the main classes of new platinum drug candidates, such as sterically hindered complexes, monofunctional platinum drugs, complexes with biologically active ligands, trans-configured and polynuclear platinum complexes, platinum(IV) prodrugs and platinum-based drug delivery systems. For each class of compounds, a detailed overview of the mechanism of action is given, the cytotoxicity is compared to that of the clinically used platinum drugs, and the clinical perspectives are discussed. A critical analysis of lessons to be learned is presented. Finally, a general outlook regarding future directions in the field of new platinum drugs is given. PMID:26886018

  4. Phosphorescent Organic Light Emitting Diodes Implementing Platinum Complexes

    NASA Astrophysics Data System (ADS)

    Ecton, Jeremy Exton

    Organic light emitting diodes (OLEDs) are a promising approach for display and solid state lighting applications. However, further work is needed in establishing the availability of efficient and stable materials for OLEDs with high external quantum efficiency's (EQE) and high operational lifetimes. Recently, significant improvements in the internal quantum efficiency or ratio of generated photons to injected electrons have been achieved with the advent of phosphorescent complexes with the ability to harvest both singlet and triplet excitons. Since then, a variety of phosphorescent complexes containing heavy metal centers including Os, Ni, Ir, Pd, and Pt have been developed. Thus far, the majority of the work in the field has focused on iridium based complexes. Platinum based complexes, however, have received considerably less attention despite demonstrating efficiency's equal to or better than their iridium analogs. In this study, a series of OLEDs implementing newly developed platinum based complexes were demonstrated with efficiency's or operational lifetimes equal to or better than their iridium analogs for select cases. In addition to demonstrating excellent device performance in OLEDs, platinum based complexes exhibit unique photophysical properties including the ability to form excimer emission capable of generating broad white light emission from a single emitter and the ability to form narrow band emission from a rigid, tetradentate molecular structure for select cases. These unique photophysical properties were exploited and their optical and electrical properties in a device setting were elucidated. Utilizing the unique properties of a tridentate Pt complex, Pt-16, a highly efficient white device employing a single emissive layer exhibited a peak EQE of over 20% and high color quality with a CRI of 80 and color coordinates CIE(x=0.33, y=0.33). Furthermore, by employing a rigid, tetradentate platinum complex, PtN1N, with a narrow band emission into a

  5. Fraction of platinum surface covered with carbonaceous species following hydrogenolysis of hexane on platinum alumina catalysts

    SciTech Connect

    Rivera Latas, F.J.

    1986-01-01

    Catalytic naphtha reforming plays a major role in satisfying the demand for unleaded, high octane gasoline. Hydrogen containing carbonaceous deposits (coke) accumulation on the surface of the catalysts during reforming operation. This study investigated the following question: what is the fraction of the platinum surface covered with the deposits following a typical reforming reaction. These observations prompted us to prepare a platinum-alumina catalyst with a high metal content (5%) to enhance the sensitivity of experiments designed to examine the platinum surface following hexane hydrogenolysis. The reaction was selected because it is a good model reaction for catalytic reforming and it was also studied by the Somorjai group in the higher temperature range of their work. Hydrogenolysis of hexane was carried out in a flow system for 3 h at 713 K, at atmospheric pressure, and around 0.1 total conversion. The catalyst was cooled down to room temperature in the reactant mixture, and the fraction of surface platinum atoms exposed was measured in situ by four independent methods: titration of adsorbed oxygen by dihydrogen, chemisorption of carbon monoxide, infra-red spectroscopy of carbon monoxide bonded to platinum, and rate of ethylene hydrogenation. Independent gravimetric studies showed that coke deposits of around 1% by weight were formed on the same catalyst during hydrogenolysis of hexane under similar conditions. Each of the four methods indicate that approximately 50% of the platinum surface remains exposed under the conditions.

  6. Skin Sensitizing Potency of Halogenated Platinum Salts.

    EPA Science Inventory

    The relationship between occupational exposure to halogenated platinum (Pt) salts and Pt-specific allergic sensitization is well-established. Although human case reports and clinical studies demonstrate that Pt salts are potent skin sensitizers, no studies have been published tha...

  7. Evaluation of industrial platinum resistance thermometers

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Dillontownes, Lawrence A.; Alderfer, David W.

    1987-01-01

    The calibration and stability of four surface temperature measuring industrial platinum resistance thermometers for use in the temperature range -120 C to 160 C was investigated. It was found that the calibration formulation of the International Practical Temperature Scale of 1968 provided the most accurate calibration. It was also found that all the resistance thermometers suffered from varying degrees of instability and hysteresis.

  8. Agent Orange

    MedlinePlus

    ... Index Agent Orange Agent Orange Home Facts about Herbicides Veterans' Diseases Birth Defects Benefits Exposure Locations Provider ... millions of gallons of Agent Orange and other herbicides on trees and vegetation during the Vietnam War. ...

  9. Epitaxial Overgrowth of Platinum on Palladium Nanocrystals

    SciTech Connect

    Jiang, M.; Zhu, Y.; Lim, B.; Tao, J.; Camargo, P.H.C.; Ma, C.; Xia, Y.

    2010-11-01

    This paper describes a systematic study on the epitaxial overgrowth of Pt on well-defined Pdnanocrystals with different shapes (and exposed facets), including regular octahedrons, truncated octahedrons, and cubes. Two different reducing agents, i.e., citric acid and L-ascorbic acid, were evaluated and compared for the reduction of K{sub 2}PtCl{sub 4} in an aqueous solution in the presence of Pdnanocrystal seeds. When citric acid was used as a reducing agent, conformal overgrowth of octahedral Pt shells on regular and truncated octahedrons of Pd led to the formation of Pd-Pt core-shell octahedrons, while non-conformal overgrowth of Pt on cubic Pd seeds resulted in the formation of an incomplete octahedral Pt shell. On the contrary, localized overgrowth of Pt branches was observed when L-ascorbic acid was used as a reducing agent regardless of the facets expressed on the surface of Pdnanocrystal seeds. This work shows that both the binding affinity of a reducing agent to the Pt surface and the reduction kinetics for a Pt precursor play important roles in determining the mode of Pt overgrowth on Pdnanocrystal surface.

  10. Effect of neoadjuvant chemotherapy on platinum resistance in stage IIIC and IV epithelial ovarian cancer.

    PubMed

    Luo, Yanlin; Lee, Maria; Kim, Hee Seung; Chung, Hyun Hoon; Song, Yong Sang

    2016-09-01

    It remains controversial whether neoadjuvant chemotherapy (NACT) followed by interval debulking surgery (IDS) induces chemoresistance in advanced epithelial ovarian cancer (EOC) compared with primary debulking surgery (PDS). The aim of this study was to compare platinum-resistant recurrence following treatment with NACT-IDS or PDS in patients with stage IIIC and IV EOC.We retrospectively reviewed the records of 341 patients who underwent PDS or NACT-IDS for Federation of Gynecology and Obstetrics stage IIIC or IV EOC between March 1990 and December 2010. Risk factors of platinum resistance, including NACT, postoperative residual tumor size, and various clinicopathological factors, were evaluated by univariate and multivariate logistic regression analyses. Survival analysis was performed by the Kaplan-Meier method and Cox regression modeling to measure overall survival (OS).Of 341 patients, 58 (17.0%) underwent NACT-IDS and 283 (83.0%) were treated with PDS. Twenty-nine (50.0%) patients developed platinum-resistant disease at first relapse after NACT-IDS and 99 (35.0%) patients recurred after PDS (P = 0.033). In the multivariate logistic regression analyses, NACT-IDS and postoperative residual tumor mass >1 cm were risk factors for platinum-resistant recurrence (adjusted odds ratios 2.950 and 2.915; 95% confidence intervals [CIs] 1.572-5.537 and 1.780-4.771, P = 0.001 and 0.000, respectively). Postoperative residual tumor mass >1 cm and platinum-resistant disease were significantly correlated with shorter OS (adjusted hazard ratios 1.579 and 4.078; 95% CI 1.193-2.089 and 3.074-5.412, P = 0.001 and 0.000, respectively), whereas NACT-IDS did not extend OS.NACT-IDS increases the risk of platinum-resistant recurrence in patients with stage IIIC and IV EOC. PMID:27603388

  11. Platinum-induced neurotoxicity and preventive strategies: past, present, and future.

    PubMed

    Avan, Abolfazl; Postma, Tjeerd J; Ceresa, Cecilia; Avan, Amir; Cavaletti, Guido; Giovannetti, Elisa; Peters, Godefridus J

    2015-04-01

    Neurotoxicity is a burdensome side effect of platinum-based chemotherapy that prevents administration of the full efficacious dosage and often leads to treatment withdrawal. Peripheral sensory neurotoxicity varies from paresthesia in fingers to ataxic gait, which might be transient or irreversible. Because the number of patients being treated with these neurotoxic agents is still increasing, the need for understanding the pathogenesis of this dramatic side effect is critical. Platinum derivatives, such as cisplatin and carboplatin, harm mainly peripheral nerves and dorsal root ganglia neurons, possibly because of progressive DNA-adduct accumulation and inhibition of DNA repair pathways (e.g., extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase/stress-activated protein kinase, and p38 mitogen-activated protein kinass), which finally mediate apoptosis. Oxaliplatin, with a completely different pharmacokinetic profile, may also alter calcium-sensitive voltage-gated sodium channel kinetics through a calcium ion immobilization by oxalate residue as a calcium chelator and cause acute neurotoxicity. Polymorphisms in several genes, such as voltage-gated sodium channel genes or genes affecting the activity of pivotal metal transporters (e.g., organic cation transporters, organic cation/carnitine transporters, and some metal transporters, such as the copper transporters, and multidrug resistance-associated proteins), can also influence drug neurotoxicity and treatment response. However, most pharmacogenetics studies need to be elucidated by robust evidence. There are supportive reports about the effectiveness of several neuroprotective agents (e.g., vitamin E, glutathione, amifostine, xaliproden, and venlafaxine), but dose adjustment and/or drug withdrawal seem to be the most frequently used methods in the management of platinum-induced peripheral neurotoxicity. To develop alternative options in the treatment of platinum-induced neuropathy, studies on in vitro

  12. Platinum-Induced Neurotoxicity and Preventive Strategies: Past, Present, and Future

    PubMed Central

    Avan, Abolfazl; Postma, Tjeerd J.; Ceresa, Cecilia; Avan, Amir; Cavaletti, Guido; Giovannetti, Elisa

    2015-01-01

    Neurotoxicity is a burdensome side effect of platinum-based chemotherapy that prevents administration of the full efficacious dosage and often leads to treatment withdrawal. Peripheral sensory neurotoxicity varies from paresthesia in fingers to ataxic gait, which might be transient or irreversible. Because the number of patients being treated with these neurotoxic agents is still increasing, the need for understanding the pathogenesis of this dramatic side effect is critical. Platinum derivatives, such as cisplatin and carboplatin, harm mainly peripheral nerves and dorsal root ganglia neurons, possibly because of progressive DNA-adduct accumulation and inhibition of DNA repair pathways (e.g., extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase/stress-activated protein kinase, and p38 mitogen-activated protein kinass), which finally mediate apoptosis. Oxaliplatin, with a completely different pharmacokinetic profile, may also alter calcium-sensitive voltage-gated sodium channel kinetics through a calcium ion immobilization by oxalate residue as a calcium chelator and cause acute neurotoxicity. Polymorphisms in several genes, such as voltage-gated sodium channel genes or genes affecting the activity of pivotal metal transporters (e.g., organic cation transporters, organic cation/carnitine transporters, and some metal transporters, such as the copper transporters, and multidrug resistance-associated proteins), can also influence drug neurotoxicity and treatment response. However, most pharmacogenetics studies need to be elucidated by robust evidence. There are supportive reports about the effectiveness of several neuroprotective agents (e.g., vitamin E, glutathione, amifostine, xaliproden, and venlafaxine), but dose adjustment and/or drug withdrawal seem to be the most frequently used methods in the management of platinum-induced peripheral neurotoxicity. To develop alternative options in the treatment of platinum-induced neuropathy, studies on in vitro

  13. Platinum anticancer drugs. From serendipity to rational design.

    PubMed

    Monneret, C

    2011-11-01

    The discovery of cis-platin was serendipitous. In 1965, Rosenberg was looking into the effects of an electric field on the growth of Escherichia coli bacteria. He noticed that bacteria ceased to divide when placed in an electric field but what Rosenberg also observed was a 300-fold increase in the size of the bacteria. He attributed this to the fact that somehow the platinum-conducting plates were inducing cell growth but inhibiting cell division. It was later deduced that the platinum species responsible for this was cis-platin. Rosenberg hypothesized that if cis-platin could inhibit bacterial cell division it could also stop tumor cell growth. This conjecture has proven correct and has led to the introduction of cis-platin in cancer therapy. Indeed, in 1978, six years after clinical trials conducted by the NCI and Bristol-Myers-Squibb, the U.S. Food and Drug Administration (FDA) approved cis-platin under the name of Platinol(®) for treating patients with metastatic testicular or ovarian cancer in combination with other drugs but also for treating bladder cancer. Bristol-Myers Squibb also licensed carboplatin, a second-generation platinum drug with fewer side effects, in 1979. Carboplatin entered the U.S. market as Paraplatin(®) in 1989 for initial treatment of advanced ovarian cancer in established combination with other approved chemotherapeutic agents. Numerous platin derivatives have been further developed with more or less success and the third derivative to be approved in 1994 was oxaliplatin under the name of Eloxatin(®). It was the first platin-based drug to be active against metastatic colorectal cancer in combination with fluorouracil and folinic acid. The two others platin-based drugs to be approved were nedaplatin (Aqupla(®)) in Japan and lobaplatin in China, respectively. More recently, a strategy to overcome resistance due to interaction with thiol-containing molecules led to the synthesis of picoplatin in which one of the amines linked to Pt

  14. A common polymorphism in the 5' UTR of ERCC5 creates an upstream ORF that confers resistance to platinum-based chemotherapy.

    PubMed

    Somers, Joanna; Wilson, Lindsay A; Kilday, John-Paul; Horvilleur, Emilie; Cannell, Ian G; Pöyry, Tuija A A; Cobbold, Laura C; Kondrashov, Alexander; Knight, John R P; Puget, Stéphanie; Grill, Jacques; Grundy, Richard G; Bushell, Martin; Willis, Anne E

    2015-09-15

    We show that a common polymorphic variant in the ERCC5 5' untranslated region (UTR) generates an upstream ORF (uORF) that affects both the background expression of this protein and its ability to be synthesized following exposure to agents that cause bulky adduct DNA damage. Individuals that harbor uORF1 have a marked resistance to platinum-based agents, illustrated by the significantly reduced progression-free survival of pediatric ependymoma patients treated with such compounds. Importantly, inhibition of DNA-PKcs restores sensitivity to platinum-based compounds by preventing uORF1-dependent ERCC5 expression. Our data support a model in which a heritable 5' noncoding mRNA element influences individuals' responses to platinum-based chemotherapy. PMID:26338418

  15. A common polymorphism in the 5′ UTR of ERCC5 creates an upstream ORF that confers resistance to platinum-based chemotherapy

    PubMed Central

    Somers, Joanna; Wilson, Lindsay A.; Kilday, John-Paul; Horvilleur, Emilie; Cannell, Ian G.; Pöyry, Tuija A.A.; Cobbold, Laura C.; Kondrashov, Alexander; Knight, John R.P.; Puget, Stéphanie; Grill, Jacques; Grundy, Richard G.; Bushell, Martin; Willis, Anne E.

    2015-01-01

    We show that a common polymorphic variant in the ERCC5 5′ untranslated region (UTR) generates an upstream ORF (uORF) that affects both the background expression of this protein and its ability to be synthesized following exposure to agents that cause bulky adduct DNA damage. Individuals that harbor uORF1 have a marked resistance to platinum-based agents, illustrated by the significantly reduced progression-free survival of pediatric ependymoma patients treated with such compounds. Importantly, inhibition of DNA-PKcs restores sensitivity to platinum-based compounds by preventing uORF1-dependent ERCC5 expression. Our data support a model in which a heritable 5′ noncoding mRNA element influences individuals’ responses to platinum-based chemotherapy. PMID:26338418

  16. Dendrimer-Templated Ultrasmall and Multifunctional Photothermal Agents for Efficient Tumor Ablation.

    PubMed

    Zhou, Zhengjie; Wang, Yitong; Yan, Yang; Zhang, Qiang; Cheng, Yiyun

    2016-04-26

    Ultrasmall and multifunctional nanoparticles are highly desirable for photothermal cancer therapy, but the synthesis of these nanoparticles remains a huge challenge. Here, we used a dendrimer as a template to synthesize ultrasmall photothermal agents and further modified them with multifunctional groups. Dendrimer-encapsulated nanoparticles (DENPs) including copper sulfide, platinum, and palladium nanoparticles possessed a sub-5 nm size and exhibited an excellent photothermal effect. DENPs were further modified with TAT or RGD peptides to facilitate their cellular uptake and targeting delivery to tumors. They were also decorated with fluorescent probes for real-time imaging and tracking of the particles' distribution. The in vivo study revealed RGD-modified DENPs efficiently reduced the tumor growth upon near-infrared irradiation. In all, our study provides a facile and flexible scaffold to prepare ultrasmall and multifunctional photothermal agents. PMID:27054555

  17. Measurement of the sequence specificity of covalent DNA modification by antineoplastic agents using Taq DNA polymerase.

    PubMed Central

    Ponti, M; Forrow, S M; Souhami, R L; D'Incalci, M; Hartley, J A

    1991-01-01

    A polymerase stop assay has been developed to determine the DNA nucleotide sequence specificity of covalent modification by antineoplastic agents using the thermostable DNA polymerase from Thermus aquaticus and synthetic labelled primers. The products of linear amplification are run on sequencing gels to reveal the sites of covalent drug binding. The method has been studied in detail for a number of agents including nitrogen mustards, platinum analogues and mitomycin C, and the sequence specificities obtained accord with those obtained by other procedures. The assay is advantageous in that it is not limited to a single type of DNA lesion (as in the piperidine cleavage assay for guanine-N7 alkylation), does not require a strand breakage step, and is more sensitive than other primer extension procedures which have only one cycle of polymerization. In particular the method has considerable potential for examining the sequence selectivity of damage and repair in single copy gene sequences in genomic DNA from cells. Images PMID:2057351

  18. Platinum stable isotopes in ferromanganese crust and nodules

    NASA Astrophysics Data System (ADS)

    Corcoran, Loretta; Seward, Terry; Handler, Monica R.

    2015-04-01

    Hydrogenetic ferromanganese (Fe-Mn) crust and nodules are slow-growing chemical sediments that form by direct precipitation from seawater, resulting in a record of changing seawater chemistry. These sediments are the primary sink for platinum in the modern oxic marine environment, hosting well-documented enrichments over other platinum-group elements (PGEs): the Pt anomaly [1]. Platinum is a non-bio-essential, highly siderophile, transition metal with six stable isotopes (190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt) with several oxidation states (Pt0, Pt2+ and Pt4+). Platinum is generally considered to exist in the hydrosphere as Pt2+ although its behaviour in the marine environment is poorly constrained, and Pt4+may also be present. Variations in ocean redox state, together with changes in source fluxes to the oceans, may therefore lead to small variations (< ±1) in the stable isotopic composition of marine platinum, raising the potential of adding platinum to the growing arsenal of paleoceanographic tracers. A method has been developed to measure the platinum isotopic composition using double spike MC-ICPMS analysis [2]and applied to a global suite of modern Fe-Mn crust and nodules. Combining synchrotron XAFS analyses of platinum adsorbed onto Fe-Mn oxide and oxyhydroxide surfaces to determine oxidation state and bonding environment, with platinum stable isotopic measurements allowing us to evaluate both platinum incorporation onto these sediments and the associated degree of platinum isotopic fractionation. Leaching experiments conducted on platinum rich terrestrial materials underwent platinum stable isotopic measurement as an analogue for the Pt isotopic fractionation associated with continental weathering. [1] Hodge, V.F. et al. (1985) Earth and Planetary Science Letters, 72, 158-162. [2] Creech, J. et al. (2013) Journal of Analytical Atomic Spectrometry, 28. 853-865.

  19. Platinum-group elements: so many excellent properties

    USGS Publications Warehouse

    Zientek, Michael L.; Loferski, Patricia J.

    2014-01-01

    The platinum-group elements (PGE) include platinum, palladium, rhodium, ruthenium, iridium, and osmium. These metals have similar physical and chemical properties and occur together in nature. The properties of PGE, such as high melting points, corrosion resistance, and catalytic qualities, make them indispensable to many industrial applications. PGE are strategic and critical materials for many nations because they are essential for important industrial applications but are mined in a limited number of places and have no adequate substitutes. Exploration and mining companies have found approximately 104,000 metric tons of PGE (with minor gold) in mineral deposits around the world that could be developed. For PGE, almost all known production and resources are associated with three geologic features: the Bushveld Complex, a layered mafic-to-ultramafic intrusion in South Africa; the Great Dyke, a layered mafic-to-ultramafic intrusion in Zimbabwe; and sill-like intrusions associated with flood basalts in the Noril’sk-Talnakh area, Russia. To help predict where PGE supplies might be located, USGS scientists study how and where PGE resources are concentrated in the Earth's crust and use that knowledge to assess the likelihood that undiscovered PGE deposits may exist. Techniques used for assessing mineral resources were developed by the USGS to support the stewardship of Federal lands and evaluate mineral resource availability in a global context. The USGS also compiles statistics and information on the worldwide supply, demand, and flow of PGE. These data are all used to inform U.S. national policymakers.

  20. Nonuniformity effects in a hybrid platinum silicide imaging device

    NASA Astrophysics Data System (ADS)

    Dereniak, Eustace L.; Perry, David L.

    1992-05-01

    The objective of this project was twofold. The first objective was to characterize the Hughes Aircraft Company CRC-365 platinum silicide imaging device in a starting infrared sensor system. The CRC-365 is a hybrid 256 x 256 IR focal plane array that operates in the 3-5 micrometer thermal infrared band. A complete sensor and computer interface were built for these tests, using, plans provided by the Rome Laboratory at Hanscom AFB. Testing of the device revealed largely satisfactory performance, with notable exception in the areas of temporal response, temporal noise, and electrical crosstalk. The second objective of this research was to advance the understanding of how detector nonuniformity effects reduce the performance of sensors of this type. Notable accomplishments in this area included a complete linear analysis of corrected thermal imaging in platinum silicide sensors, a nonlinear analysis of the CRC-365's expected performance, analysis of its actual performance when operated with nonuniformity correction, and the development of a new figure of merit. It was demonstrated that the CRC-365 is capable of maintaining background-noise-limited performance over at least a 40 K target temperature range, when operated with two-point nonuniformity correction.

  1. Pharmacologic inhibition of ATR and ATM offers clinically important distinctions to enhancing platinum or radiation response in ovarian, endometrial, and cervical cancer cells

    PubMed Central

    Teng, Pang-ning; Bateman, Nicholas W.; Darcy, Kathleen M.; Hamilton, Chad A.; Maxwell, George Larry; Bakkenist, Christopher J.; Conrads, Thomas P.

    2015-01-01

    Objective Significant reductions in gynecologic (GYN) cancer mortality and morbidity require treatments that prevent and reverse resistance to chemotherapy and radiation. The objective of this study was to determine if pharmacologic inhibition of key DNA damage response kinases in GYN cancers would enhance cell killing by platinum-based chemotherapy and radiation. Methods A panel of human ovarian, endometrial and cervical cancer cell lines were treated with platinum drugs or ionizing radiation (IR) along with small molecule pharmacological kinase inhibitors of Ataxia telangiectasia mutated (ATM) and ATM and Rad-3-related (ATR). Results Pharmacologic inhibition of ATR significantly enhanced platinum drug response in all GYN cancer cell lines tested, whereas inhibition of ATM did not enhance the response to platinum drugs. Co-inhibition of ATM and ATR did not enhance platinum kill beyond that observed by inhibition of ATR alone. By contrast, inhibiting either ATR or ATM enhanced the response to IR in all GYN cancer cells, with further enhancement achieved with co-inhibition. Conclusions These studies highlight actionable mechanisms operative in GYN cancer cells with potential to maximize response of platinum agents and radiation in newly diagnosed as well as recurrent gynecologic cancers. PMID:25560806

  2. Nuclear microprobe determination of platinum quantitative distribution in rat brain tumors after cisplatin or carboplatin injection for PAT treatment of glioma

    NASA Astrophysics Data System (ADS)

    Ortega, R.; Biston, M.-C.; Devès, G.; Bohic, S.; Carmona, A.

    2005-04-01

    Conventional radiotherapy of high-grade glioma is unsuccessful since less than 50% of patients survive at 6 months, therefore glioma treatment is still challenging. A new radiotherapy procedure has been recently proposed, the photoactivation therapy (PAT), associating synchrotron radiation with a chemotherapy agent, such as cisplatin. PAT aims at using the monochromaticity and the very high brilliance of the synchrotron radiation for selective excitation of a high-Z compound introduced in tumor cell DNA to maximize the photoelectric effect probability, thus increasing local toxicity. Synchrotron irradiation of cisplatin at the platinum absorption K-edge resulted in a dramatic increase in life span relative to median survival time in the F98 glioma model in Fisher rat. In the purpose to optimize the platinum concentration into the tumor, the platinum content of irradiated target needs to be quantified. These results will enable to correlate injected dose to cellular platinum content in the tumor at the time of irradiation, and to study the spatial diffusion and distribution of the platinum into the tumor and the surrounding healthy tissues from the point of injection. Male Fisher 344 rats were inoculated with 103 F98 glioma cells. Thirteen days after stereotactic inoculation, intracerebral injection at the tumor site of 40 μg of carboplatin and 3 or 5 μg of cisplatin was performed. Platinum quantitative distribution in tumors and adjacent brain tissues was determined using μ-PIXE and μ-RBS analysis.

  3. Synthesis of Bimetallic Platinum Nanoparticles for Biosensors

    PubMed Central

    Leteba, Gerard M.; Lang, Candace I.

    2013-01-01

    The use of magnetic nanomaterials in biosensing applications is growing as a consequence of their remarkable properties; but controlling the composition and shape of metallic nanoalloys is problematic when more than one precursor is required for wet chemistry synthesis. We have developed a successful simultaneous reduction method for preparation of near-spherical platinum-based nanoalloys containing magnetic solutes. We avoided particular difficulties in preparing platinum nanoalloys containing Ni, Co and Fe by the identification of appropriate synthesis temperatures and chemistry. We used transmission electron microscopy (TEM) to show that our particles have a narrow size distribution, uniform size and morphology, and good crystallinity in the as-synthesized condition. Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) confirms the coexistence of Pt with the magnetic solute in a face-centered cubic (FCC) solid solution. PMID:23941910

  4. Raman characterization of platinum diselenide thin films

    NASA Astrophysics Data System (ADS)

    O’Brien, Maria; McEvoy, Niall; Motta, Carlo; Zheng, Jian-Yao; Berner, Nina C.; Kotakoski, Jani; Elibol, Kenan; Pennycook, Timothy J.; Meyer, Jannik C.; Yim, Chanyoung; Abid, Mohamed; Hallam, Toby; Donegan, John F.; Sanvito, Stefano; Duesberg, Georg S.

    2016-06-01

    Platinum diselenide (PtSe2) is a newly discovered 2D material which is of great interest for applications in electronics and catalysis. PtSe2 films were synthesized by thermally assisted selenization of predeposited platinum films and scanning transmission electron microscopy revealed the crystal structure of these films to be 1T. Raman scattering of these films was studied as a function of film thickness, laser wavelength and laser polarization. E g and A 1g Raman active modes were identified using polarization measurements in the Raman setup. These modes were found to display a clear position and intensity dependence with film thickness, for multiple excitation wavelengths, and their peak positions agree with simulated phonon dispersion curves for PtSe2. These results highlight the practicality of using Raman spectroscopy as a prime characterization technique for newly synthesized 2D materials.

  5. Remarkable NO oxidation on single supported platinum atoms

    SciTech Connect

    Narula, Chaitanya K.; Allard, Lawrence F.; Stocks, G. M.; Moses-DeBusk, Melanie

    2014-11-28

    Our first-principles density functional theoretical modeling suggests that NO oxidation is feasible on fully oxidized single θ-alumina-supported platinum atoms via a modified Langmuir-Hinshelwood pathway. This is in contrast to the known decrease in NO oxidation activity of supported platinum with decreasing Pt particle size believed to be due to increased platinum oxidation. In order to validate our theoretical study, we evaluated single θ-Al2O3-supported platinum atoms and found them to exhibit remarkable NO oxidation activity. A comparison of turnover frequencies (TOF) of single supported Pt atoms with those of platinum particles for NO oxidation shows that single supported Pt atoms are as active as fully formed platinum particles. The overall picture of NO oxidation on supported Pt is that NO oxidation activity decreases with decreasing Pt particle size but accelerates when Pt is present only as single atoms.

  6. Remarkable NO oxidation on single supported platinum atoms

    DOE PAGESBeta

    Narula, Chaitanya K.; Allard, Lawrence F.; Stocks, G. M.; Moses-DeBusk, Melanie

    2014-11-28

    Our first-principles density functional theoretical modeling suggests that NO oxidation is feasible on fully oxidized single θ-alumina-supported platinum atoms via a modified Langmuir-Hinshelwood pathway. This is in contrast to the known decrease in NO oxidation activity of supported platinum with decreasing Pt particle size believed to be due to increased platinum oxidation. In order to validate our theoretical study, we evaluated single θ-Al2O3-supported platinum atoms and found them to exhibit remarkable NO oxidation activity. A comparison of turnover frequencies (TOF) of single supported Pt atoms with those of platinum particles for NO oxidation shows that single supported Pt atoms aremore » as active as fully formed platinum particles. The overall picture of NO oxidation on supported Pt is that NO oxidation activity decreases with decreasing Pt particle size but accelerates when Pt is present only as single atoms.« less

  7. Remarkable NO oxidation on single supported platinum atoms

    PubMed Central

    Narula, Chaitanya K.; Allard, Lawrence F.; Stocks, G. M.; Moses-DeBusk, Melanie

    2014-01-01

    Our first-principles density functional theoretical modeling suggests that NO oxidation is feasible on fully oxidized single θ-Al2O3 supported platinum atoms via a modified Langmuir-Hinshelwood pathway. This is in contrast to the known decrease in NO oxidation activity of supported platinum with decreasing Pt particle size believed to be due to increased platinum oxidation. In order to validate our theoretical study, we evaluated single θ-Al2O3 supported platinum atoms and found them to exhibit remarkable NO oxidation activity. A comparison of turnover frequencies (TOF) of single supported Pt atoms with those of platinum particles for NO oxidation shows that single supported Pt atoms are as active as fully formed platinum particles. Thus, the overall picture of NO oxidation on supported Pt is that NO oxidation activity decreases with decreasing Pt particle size but accelerates when Pt is present only as single atoms. PMID:25429995

  8. GREEN AND CONTROLLED SYNTHESIS OF GOLD AND PLATINUM NANOMATERIALS USING VITAMIN B2: DENSITY-ASSISTED SELF-ASSEMBLY OF NANOSPHERES, WIRES AND RODS

    EPA Science Inventory

    For the first time, we report density-assisted self-assembly and efficient synthesis of gold (Au) and platinum (Pt) nanospheres, nanowires and nanorods using vitamin B2 (riboflavin) without employing any special capping or dispersing agent at room temperature; this env...

  9. Root bark extracts of Juncus effusus and Paeonia suffruticosa protect salivary gland acinar cells from apoptotic cell death induced by cis-platinum (II) diammine dichloride.

    PubMed

    Mukudai, Yoshiki; Kondo, Seiji; Shiogama, Sunao; Koyama, Tomoyuki; Li, Chunnan; Yazawa, Kazunaga; Shintani, Satoru

    2013-12-01

    Cis-platinum (II) diammine dichloride (CDDP) is a platinum-based anticancer agent, and is often used for chemotherapy for malignant tumors, albeit CDDP has serious side-effects, including xerostomia (dry mouth). Since patients with xerostomia have reduced quality of life, it is urgent and important to identify nontoxic and natural agents capable of reducing the adverse effect of chemotherapy on salivary gland function. Therefore, we commenced an institutional collaborative project in which candidates of herbal extracts were selected from more than 400 bioactive herbal products for their potential therapeutic effects not only on xerostomia, but also on oral diseases. In the present study, we report on two Chinese medical herbal extracts from the root barks of Juncus effusus and Paeonia suffruticosa. The two extracts showed a protective effect in NS-SV-Ac cells from the cytotoxicity and apoptosis caused by CDDP. The effect was dependent on the p53 pathway, protein kinase B/Akt 1 and mitochondrial apoptosis-related proteins (i.e. Bcl-2 and Bax), but was not dependent on nuclear factor κB. Notably, the apoptosis-protective effect of the extracts was not observed in adenocystic carcinoma cell lines. Although these extracts have been utilized in traditional Chinese medicine for hundreds of years, there are no reports to our knowledge, on their therapeutic effects on xerostomia. Thus, in the present study, we elucidated the potency of these herbal extracts as novel candidates for xerostomia to improve the quality of life of patients undergoing chemotherapy. PMID:24064583

  10. RF magnetron sputtering of thick platinum coatings on glass microspheres

    SciTech Connect

    Meyer, S.F.; Hsieh, E.J.; Burt, R.J.

    1980-05-28

    Thick platinum coatings on glass microspheres are needed for proposed Laser Fusion targets. The spherical nature of these substrates coupled with the small dimensions (approx. 100 ..mu..m OD) make it difficult to achieve a smooth and uniform coating. Coating problems encountered include a rough surface and porous microstructure from the oblique incidence and lack of temperature and bias control, clumping of the microspheres causing non-uniformities, and particle accumulation causing cone defects. Sputtering parameters significantly affecting the coatings include total pressure, DC substrate bias, and the addition of doping gases. Using an ultrasonic vibrating screened cage and RF magnetron Sputtergun, we have successfully batch coated microspheres with up to 6 ..mu..m of Pt, with a surface roughness of 200 nm, thickness non-concentricity of 300 nm, and density greater than 98% of bulk Pt.

  11. Aqueous synthesis of near-infrared highly fluorescent platinum nanoclusters

    NASA Astrophysics Data System (ADS)

    García Fernández, Jenifer; Trapiella-Alfonso, Laura; Costa-Fernández, José M.; Pereiro, Rosario; Sanz-Medel, Alfredo

    2015-05-01

    A one-step synthesis of near infrared fluorescent platinum nanoclusters (PtNCs) in aqueous medium is described. The proposed optimized procedure for PtNC synthesis is rather simple, fast and it is based on the direct metal reduction with NaBH4. Bidentated thiol ligands (lipoic acid) were selected as nanoclusters stabilizers in water media. The structural characterization revealed attractive features of the PtNCs, including small size, high water solubility, near-infrared luminescence centered at 680 nm, long-term stability and the highest quantum yield in water reported so far (47%) for PtNCs. Moreover, their stability in different pH media and an ionic strength of 0.2 M NaCl was studied and no significant changes in fluorescence emission were detected. In brief, they offer a new type of fluorescent noble metal nanoprobe with a great potential to be applied in several fields, including biolabeling and imaging experiments.

  12. Antifungal agents.

    PubMed

    Ryder, N S

    1999-12-01

    At this year's ICAAC Meeting, new data on approximately 20 different antifungal agents were presented, while no new agents were disclosed. Drugs in late development include the triazoles, voriconazole (Pfizer Ltd) and Sch-56592 (Schering-Plough Corp), and the echinocandins, caspofungin (Merck & Co Inc) and FK-463 (Fujisawa Pharmaceutical Co Ltd). In contrast to previous years, presentations on these and earlier developmental compounds were relatively modest in scope, with few significant new data. Little new information appeared on the most recent novel class of agents, the sordarins (Glaxo Wellcome plc). Early clinical results were presented for FK-463, showing acceptable tolerability and dose-dependent efficacy in AIDS-associated esophageal candidiasis. A new liposomal formulation of nystatin (Nyotran; Aronex Pharmaceuticals Inc) was shown to be equivalent to conventional amphotericin B in empiric therapy of presumed fungal infection in neutropenic patients, but with reduced toxicity. Intravenous itraconazole (Janssen Pharmaceutica NV) was an effective prophylactic therapy in invasive pulmonary aspergillosis, while oral itraconazole was discussed as a treatment for fungal infection in heart and liver transplant patients. The allylamine compound, terbinafine (Novartis AG), showed good clinical efficacy against fungal mycetoma, a serious tropical infection. A major highlight was the first presentation of inhibitors of fungal efflux pumps as a strategy for overcoming resistance. MC-510027 (milbemycin alpha-9; Microcide Pharmaceuticals Inc) and its derivatives, potentiated the antifungal activity of triazoles and terbinafine in a number of Candida spp. Another pump inhibitor, MC-005172 (Microcide Pharmaceuticals Inc) showed in vivo potentiation of fluconazole in a mouse kidney infection model. Microcide Pharmaceuticals Inc also presented inhibitors of bacterial efflux pumps. PMID:16113946

  13. Pros and cons of bifunctional platinum(IV) antitumor prodrugs: two are (not always) better than one.

    PubMed

    Gabano, Elisabetta; Ravera, Mauro; Osella, Domenico

    2014-07-14

    This article evaluates the efficacy and applicability of bifunctional prodrugs consisting of a six-coordinate Pt(iv) octahedral core and one or more bioactive molecules. The platinum(iv) complexes release upon reduction the corresponding cytotoxic Pt(ii) agents and the bioactive molecules, able to inhibit some biochemical mechanisms of cancer growth and/or prevent the deactivation of the Pt(ii) metabolites. PMID:24874896

  14. Platinum nanoparticles from size adjusted functional colloidal particles generated by a seeded emulsion polymerization process.

    PubMed

    Vogel, Nicolas; Ziener, Ulrich; Manzke, Achim; Plettl, Alfred; Ziemann, Paul; Biskupek, Johannes; Weiss, Clemens K; Landfester, Katharina

    2011-01-01

    The benefits of miniemulsion and emulsion polymerization are combined in a seeded emulsion polymerization process with functional seed particles synthesized by miniemulsion polymerization. A systematic study on the influence of different reaction parameters on the reaction pathway is conducted, including variations of the amount of monomer fed, the ratio of initiator to monomer and the choice of surfactant and composition of the continuous phase. Critical parameters affecting the control of the reaction are determined. If carefully controlled, the seeded emulsion polymerization with functional seed particles yields monodisperse particles with adjustable size and functionalities. Size-adjusted platinum-acetylacetonate containing latex particles with identical seed particles and varied shell thicknesses are used to produce arrays of highly ordered platinum nanoparticles with different interparticle distances but identical particle sizes. For that, a self-assembled monolayer of functional colloids is prepared on a solid substrate and subsequently treated by oxygen plasma processing in order to remove the organic constituents. This step, however, leads to a saturated state of a residual mix of materials. In order to determine parameters influencing this saturation state, the type of surfactant, the amount of precursor loading and the size of the colloids are varied. By short annealing at high temperatures platinum nanoparticles are generated from the saturated state particles. Typically, the present fabrication method delivers a maximum interparticle distance of about 260 nm for well-defined crystalline platinum nanoparticles limited by deformation processes due to softening of the organic material during the plasma applications. PMID:22003452

  15. Study of bactericidal properties of carbohydrate-stabilized platinum oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Rezaei-Zarchi, Saeed; Imani, Saber; mohammad Zand, Ali; Saadati, Mojtaba; Zaghari, Zahra

    2012-09-01

    Platinum oxide nanoparticles were prepared by a simple hydrothermal route and chemical reduction using carbohydrates (fructose and sucrose) as the reducing and stabilizing agents. In comparison with other metals, platinum oxide has less environmental pollution. Therefore, Pt is considered an appropriate candidate to deal with environmental pathogens. The crystallite size of these nanoparticles was evaluated from X-ray diffraction, atomic force microscopy, and transmission electron microscopy (TEM) and was found to be 10 nm, which is the demonstration of EM bright field and transmission electron microscopy. The effect of carbohydrates on the morphology of the nanoparticles was studied using TEM. The nanoparticles were administered to the Pseudomonas stutzeri and Lactobacillus cultures, and the incubation was done at 37°C for 24 h. The nanocomposites exhibited interesting inhibitory as well as bactericidal activity against P. stutzeri and Lactobacillus species. Incorporation of nanoparticles also increased the thermal stability of the carbohydrates. The results of this paper showed that carbohydrates can serve as a carrier for platinum oxide nanoparticles, and nanocomposites can have potential biological applications.

  16. Platinum(II) Metallomesogens: New External-Stimuli-Responsive Photoluminescence Materials.

    PubMed

    Cuerva, Cristián; Campo, José A; Cano, Mercedes; Lodeiro, Carlos

    2016-07-11

    New dicatenar isoquinoline-functionalized pyrazoles, [Hpz(R(n,n)iq) ] (R(n,n)=C6 H3 (OCn H2n+1 )2 ; n=4, 6, 8, 10, 12, 14, 16, 18), have been strategically designed and synthesized to induce mesomorphic and luminescence properties into the corresponding bis(isoquinolinylpyrazolate)platinum(II) complexes [Pt(pz(R(n,n)iq) )2 ]. Thermal studies reveal that all platinum(II) compounds exhibit columnar mesophases over an exceptionally wide temperature range, above 300 °C in most cases. The photophysical behavior was also investigated in solution and in the solid state. As a consequence of the formation of Pt⋅⋅⋅Pt interactions, the weak greenish emission of the platinum derivatives turns bright orange in the mesophase. Additionally, the complexes are sensitive to a great variety of external inputs, such as temperature, mechanical grinding, pressure, solvents, and vapors. On this basis, they are used as dopant agents of a polyvinylpyrrolidone or poly(methyl methacrylate) polymer matrix to achieve stimuli-responsive thin films. PMID:27273696

  17. Lack of a role for MRP1 in platinum drug resistance in human ovarian cancer cell lines.

    PubMed Central

    Sharp, S. Y.; Smith, V.; Hobbs, S.; Kelland, L. R.

    1998-01-01

    The level of expression of the multidrug resistance-associated protein (MRP1) in a panel of human ovarian carcinoma cell lines and their variants with acquired cisplatin resistance was determined using Western blotting. No overexpression of MRP1 was detected in any of the cell lines. In addition, we have transfected the MRP1 gene into an intrinsically cisplatin-resistant cell line SKOV3, previously shown to have elevated levels of glutathione (GSH). The MRP1-transfected line SKOV3-S2 was shown to be cross-resistant to doxorubicin, vincristine and etoposide but not to paclitaxel, vinblastine and platinum agents, such as cisplatin, JM216 [bis-acetato-ammine-dichloro-cyclohexylamine platinum (IV)] and AMD473 [cis-ammine dichloro (2-methyl-pyridine) platinum (II)]. No cross-resistance to any of the platinum agents was observed in a MRP1-overexpressing human lung cancer cell line with acquired doxorubicin resistance. Reduction of GSH levels (80-90%) by buthionine sulphoximine (BSO) produced significant potentiation in cisplatin sensitivity in the parental SKOV3, the vector-alone control SKOV3-puro and the MRP1-transfected line SKOV3-S2. The degree of sensitization was similar in all cell lines (1.6-fold). However, selective sensitization by BSO to vincristine was observed in the MRP1-transfected line (4.1-fold) but not in the vector control. No significant differences were observed in cisplatin accumulation in the SKOV3-puro and the SKOV3-S2 cells, although both these transfected lines accumulated significantly more than the parental line. Our results suggest that MRP1 does not play a significant role in platinum resistance in the human tumour cell lines investigated in this study. Images Figure 2 PMID:9683290

  18. Facile synthesis of platinum-ruthenium nanodendrites supported on reduced graphene oxide with enhanced electrocatalytic properties

    NASA Astrophysics Data System (ADS)

    Zheng, Jie-Ning; Li, Shan-Shan; Chen, Fang-Yi; Bao, Ning; Wang, Ai-Jun; Chen, Jian-Rong; Feng, Jiu-Ju

    2014-11-01

    In this report, a simple and facile solvothermal method is developed for fabrication of platinum-ruthenium (PtRu) nanodendrites supported on reduced graphene oxide (PtRu-RGO) in the ethylene glycol (EG) system, using hexadecylpyridinium chloride (HDPC) as a shape-directing agent. The as-prepared nanocomposites show the superior catalytic activity and better stability towards EG oxidation, compared with RGO-supported Pt nanoparticles and commercial PtRu/C (Pt 30 wt. %, Ru 15 wt. %) catalysts. This strategy may open a new route to design and prepare advanced electrocatalysts in direct EG fuel cells.

  19. Multifunctional iron platinum stealth immunomicelles: targeted detection of human prostate cancer cells using both fluorescence and magnetic resonance imaging

    PubMed Central

    Huber, Dale L.; Monson, Todd C.; Ali, Abdul-Mehdi S.; Bisoffi, Marco; Sillerud, Laurel O.

    2011-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) are the most common type of contrast agents used in contrast agent-enhanced magnetic resonance imaging (MRI). Still, there is a great deal of room for improvement, and nanoparticles with increased MRI relaxivities are needed to increase the contrast enhancement in MRI applied to various medical conditions including cancer. We report the synthesis of superparamagnetic iron platinum nanoparticles (SIPPs) and subsequent encapsulation using PEGylated phospholipids to create stealth immunomicelles (DSPE-SIPPs) that can be specifically targeted to human prostate cancer cell lines and detected using both MRI and fluorescence imaging. SIPP cores and DSPE-SIPPs were 8.5 ± 1.6 nm and 42.9 ± 8.2 nm in diameter, respectively, and the SIPPs had a magnetic moment of 120 A m2/kg iron. J591, a monoclonal antibody against prostate specific membrane antigen (PSMA), was conjugated to the DSPE-SIPPs (J591-DSPE-SIPPs), and specific targeting of J591-DSPE-SIPPs to PSMA-expressing human prostate cancer cell lines was demonstrated using fluorescence confocal microscopy. The transverse relaxivity of the DSPE-SIPPs, measured at 4.7 Tesla, was 300.6 ± 8.5 s−1 mM−1, which is 13-fold better than commercially available SPIONs (23.8 ± 6.9 s−1 mM−1) and ~3-fold better than reported relaxivities for Feridex® and Resovist®. Our data suggest that J591-DSPE-SIPPs specifically target human prostate cancer cells in vitro, are superior contrast agents in T2-weighted MRI, and can be detected using fluorescence imaging. To our knowledge, this is the first report on the synthesis of multifunctional SIPP micelles and using SIPPs for the specific detection of prostate cancer. PMID:22121333

  20. Delay of the Blink Reflex in Patients Receiving Platinum-Analogue Chemotherapy

    PubMed Central

    Park, Kang Young; Park, Yun Hee; Chang, Hyun Jung; Cho, Eun Sol; Kim, Seok-Hyun; Kim, Woo Jin

    2016-01-01

    Objective To investigate the presence of cranial neuropathy in patients with platinum-analogue chemotherapy using electrodiagnostic evaluations. Methods Thirty-nine patients whose chemotherapy was completed within a month and 40 control subjects were enrolled in the study. Electrodiagnostic evaluation was performed using sensory and motor nerve conduction studies and blink reflex studies, in addition to the two-point discrimination test. Results The chemotherapy group had significantly longer latencies of bilateral R1 responses (left p<0.001; right p<0.001) and greater distance in two-point discrimination (p<0.001) compared to the control group. In the subgroup with peripheral polyneuropathy, the left R1 (p=0.01), both R2i (left p=0.02; right p=0.03) and the left R2c (p=0.02) were prolonged relative to those without the polyneuropathy, and both R1 (left p<0.001; right p<0.001), R2i (left p=0.01; right p=0.03), and the left R2c (p=0.01) were prolonged relative to the controls. On the other hand, the subgroup without the polyneuropathy showed only prolongation of both R1 (left p=0.006; right p<0.001) relative to the controls. Conclusion In the present study, comparison of blink reflex and two-point discrimination showed the likelihood of subclinical cranial neuropathy following platinum-analogue chemotherapy. Cranial neuropathy caused by platinum agents was more profound in patients with peripheral polyneuropathy and may be dependent on the cumulative dose of the drug. The blink reflex may be of value in detecting subclinical cranial neuropathy in patients undergoing platinum-analogue chemotherapy. PMID:26949671

  1. Platinum nanowire microelectrode arrays for neurostimulation applications: Fabrication, characterization, and in-vitro retinal cell stimulation

    NASA Astrophysics Data System (ADS)

    Whalen, John J., III

    Implantable electrical neurostimulating devices are being developed for a number of applications, including artificial vision through retinal stimulation. The epiretinal prosthesis will use a two-dimensional array microelectrodes to address individual cells of the retina. MEMS fabrication processes can produce arrays of microelectrodes with these dimensions, but there are two critical issues that they cannot satisfy. One, the stimulating electrodes are the only part of the implanted electrical device that penetrate through the water impermeable package, and must do so without sacrificing hermeticity. Two, As electrode size decreases, the current density (A cm-2 ) increases, due to increased electrochemical impedance. This reduces the amount of charge that can be safely injected into the tissue. To date, MEMS processing method, cannot produce electrode arrays with good, prolonged hermetic properties. Similarly, MEMS approaches do not account for the increased impedance caused by decreased surface area. For these reasons there is a strong motivation for the development of a water-impermeable, substrate-penetrating electrode array with low electrochemical impedance. This thesis presents a stimulating electrode array fabricated from platinum nanowires using a modified electrochemical template synthesis approach. Nanowires are electrochemically deposited from ammonium hexachloroplatinate solution into lithographically patterned nanoporous anodic alumina templates to produce microarrays of platinum nanowires. The platinum nanowires penetrating through the ceramic aluminum oxide template serve as parallel electrical conduits through the water impermeable, electrically insulating substrate. Electrode impedance can be adjusted by either controlling the nanowire hydrous platinum oxide content or by partially etching the alumina template to expose additional surface area. A stepwise approach to this project was taken. First, the electrochemistry of ammonium

  2. An Adsorptive Transfer Technique Coupled with Brdicka Reaction to Reveal the Importance of Metallothionein in Chemotherapy with Platinum Based Cytostatics

    PubMed Central

    Krizkova, Sona; Fabrik, Ivo; Huska, Dalibor; Adam, Vojtech; Babula, Petr; Hrabeta, Jan; Eckschlager, Tomas; Pochop, Pavel; Darsova, Denisa; Kukacka, Jiri; Prusa, Richard; Trnkova, Libuse; Kizek, Rene

    2010-01-01

    The drugs based on platinum metals represent one of the oldest, but also one of the most effective groups of chemotherapeutic agents. Thanks to many clinical studies it is known that resistance of tumor cells to drugs is a frequent cause of chemotherapy failure. With regard to platinum based drugs, multidrug resistance can also be connected with increased expression of low-molecular weight protein metallothionein (MT). This study aimed at investigating the interactions of MT with cisplatin or carboplatin, using the adsorptive transfer technique coupled with differential pulse voltammetry Brdicka reaction (AdTS DPV Brdicka reaction), and a comparison of in vitro results with results obtained in vivo. The results obtained from the in vitro study show a strong affinity between platinum based drugs and MT. Further, we analyzed extracts of neuroblastoma cell lines treated with cisplatin or carboplatin. It is clear that neuroblastoma UKF-NB-4 cisplatin-resistant and cisplatin-sensitive cell lines unlikely respond to the presence of the platinum-based cytostatics cisplatin and carboplatin. Finally, we determined the level of MT in samples from rabbits treated with carboplatin and patients with retinoblastoma treated with the same drug. PMID:21614176

  3. Emerging magnetic order in platinum atomic contacts and chains

    PubMed Central

    Strigl, Florian; Espy, Christopher; Bückle, Maximilian; Scheer, Elke; Pietsch, Torsten

    2015-01-01

    The development of atomic-scale structures revealing novel transport phenomena is a major goal of nanotechnology. Examples include chains of atoms that form while stretching a transition metal contact or the predicted formation of magnetic order in these chains, the existence of which is still debated. Here we report an experimental study of the magneto-conductance (MC) and anisotropic MC with atomic-size contacts and mono-atomic chains of the nonmagnetic metal platinum. We find a pronounced and diverse MC behaviour, the amplitude and functional dependence change when stretching the contact by subatomic distances. These findings can be interpreted as a signature of local magnetic order in the chain, which may be of particular importance for the application of atomic-sized contacts in spintronic devices of the smallest possible size. PMID:25649440

  4. Catalytic activities of platinum nanotubes: a density functional study

    NASA Astrophysics Data System (ADS)

    Mukherjee, Prajna; Gupta, Bikash C.; Jena, Puru

    2015-10-01

    In this work we investigate the catalytic properties of platinum nanotubes using density functional theory based calculations. In particular, we study the dissociation of hydrogen and oxygen molecules as well as oxidation of CO molecules. The results indicate that platinum nanotubes have good catalytic properties and can be effectively used in converting CO molecule to CO2.

  5. Bimetallic alloy electrocatalysts with multilayered platinum-skin surfaces

    DOEpatents

    Stamenkovic, Vojislav R.; Wang, Chao; Markovic, Nenad M.

    2016-01-26

    Compositions and methods of preparing a bimetallic alloy having enhanced electrocatalytic properties are provided. The composition comprises a PtNi substrate having a surface layer, a near-surface layer, and an inner layer, where the surface layer comprises a nickel-depleted composition, such that the surface layer comprises a platinum skin having at least one atomic layer of platinum.

  6. Determination of platinum in blood by adsorptive voltammetry.

    PubMed

    Nygren, O; Vaughan, G T; Florence, T M; Morrison, G M; Warner, I M; Dale, L S

    1990-08-01

    This work describes a sensitive method for the determination of platinum in blood, which can be used for determining the natural levels of platinum in human blood, for monitoring patients treated with platinum cytotoxic drugs, and for monitoring occupational exposure to these drugs and other platinum compounds. The method involves dry ashing of blood samples in a muffle furnace and determination of platinum by adsorptive voltammetric (AV) measurement of the catalytic reduction of protons by the platinum-formazone complex. The detection limit for a 100-microL sample of blood is 0.017 micrograms/L, with a recovery of 94% and a relative standard deviation of 7% at a platinum level of 1 microgram/L. By using this method, the natural levels of platinum in human blood were found to be in the range 0.1-2.8 micrograms/L (median = 0.6 micrograms/L). These results were verified by inductively coupled plasma mass spectrometry (ICP-MS) with blood prepared by wet ashing and using gold as an internal standard. PMID:2400106

  7. 76 FR 8627 - Revision of Class E Airspace; Platinum, AK

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-15

    ... Class E airspace at Platinum AK (75 FR 77572). Interested parties were invited to participate in this... U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71... Federal Aviation Administration 14 CFR Part 71 Revision of Class E Airspace; Platinum, AK AGENCY:...

  8. Vapor-deposited platinum as a fuel-cell catalyst

    NASA Technical Reports Server (NTRS)

    Asher, W. J.; Batzold, J. S.

    1974-01-01

    Electrodes are prepared by vacuum deposition of platinum on nickel substrate with conventional vapor-deposition apparatus. Amount of platinum loaded on substrate can be veried by changing exposure time during deposition. These electrodes are significantly more effective than conventional oxygen electrodes.

  9. Anticancer activity assessment of two novel binuclear platinum (II) complexes.

    PubMed

    Shahsavani, Mohammad Bagher; Ahmadi, Shamseddin; Aseman, Marzieh Dadkhah; Nabavizadeh, S Masoud; Rashidi, Mehdi; Asadi, Zahra; Erfani, Nasrollah; Ghasemi, Atiyeh; Saboury, Ali Akbar; Niazi, Ali; Bahaoddini, Aminollah; Yousefi, Reza

    2016-08-01

    In the current study, two binuclear Pt (II) complexes, containing cis, cis-[Me2Pt (μ-NN) (μ-dppm) PtMe2] (1), and cis,cis-[Me2Pt(μ-NN)(μ dppm) Pt((CH2)4)] (2) in which NN=phthalazine and dppm=bis (diphenylphosphino) methane were evaluated for their anticancer activities and DNA/purine nucleotide binding properties. These Pt (II) complexes, with the non-classical structures, demonstrated a significant anticancer activity against Jurkat and MCF-7 cancer cell lines. The results of ethidium bromide/acridine orange staining and Caspase-III activity suggest that these complexes were capable to stimulate an apoptotic mechanism of cell death in the cancer cells. Using different biophysical techniques and docking simulation analysis, we indicated that these complexes were also capable to interact efficiently with DNA via a non-intercalative mechanism. According to our results, substitution of cyclopentane (in complex 2) with two methyl groups (in complex 1) results in significant improvement of the complex ability to interact with DNA and subsequently to induce the anticancer activity. Overall, these binuclear Pt (II) complexes are promising group of the non-classical potential anticancer agents which can be considered as molecular templates in designing of highly efficient platinum anticancer drugs. PMID:27289447

  10. Platinum trans-Bis(borirene) complexes displaying coplanarity and communication across a platinum metal center.

    PubMed

    Braunschweig, Holger; Damme, Alexander; Dewhurst, Rian D; Kelch, Hauke; Macha, Bret B; Radacki, Krzysztof; Vargas, Alfredo; Ye, Qing

    2015-02-01

    Ambient-temperature photolysis of the aminoborylene complex [(OC)5 Cr=B=N(SiMe3 )2 ] in the presence of a series of trans-bis(alkynyl)platinum(II) precursors of the type trans-[Pt(CCAr)2 (PEt3 )2 ] (Ar=Ph, p-C6 H4 OMe, and p-C6 H4 CF3 ) successfully leads to twofold transfer of the borylene moiety [:B=N(SiMe3 )2 ] onto the alkyne functionalities. The alkynyl precursors and resultant bis(borirene)platinum(II) complexes formed are of the type trans-[Pt(B{=N(SiMe3 )2 }C=CAr)2 (PEt3 )2 ] (Ar=Ph, p-C6 H4 OMe, and p-C6 H4 CF3 ). These species have all been successfully characterized by NMR, IR, and UV/Vis spectroscopy as well as by elemental analysis. Single-crystal X-ray diffraction has verified that these trans-bis(borirene)platinum(II) complexes display coplanarity between the twin three-membered rings across the platinum core in the solid state and stand as the first examples of coplanar conformations of twin borirene systems. These complexes were modeled using density functional theory (DFT), providing information helpful in determining the ability of the transition metal core to interact with each individual borirene ring system and allowing for the observed coplanarity of these rings in the solid state. This proposed transition metal interaction with the twin borirene systems is manifested in the electronic characterization of these borirene species, which display divergent photophysical UV/Vis spectroscopic profiles compared to a previously published mono(borirene)platinum(II) complex. PMID:25430871

  11. A comparative study of the interaction of platinum with group 4A (germanium, tin and lead) porphyrins

    NASA Astrophysics Data System (ADS)

    Dy, E. S.; Kasai, H.

    2007-09-01

    Because of its vast number of applications and high price many studies have been made on how to reduce the amount of platinum in catalysts. One method includes dispersing platinum nanoparticles in porous support materials. But electrically conductive carbon-based support materials—needed for fuel cell electrodes—permit nanoparticles to migrate and form larger clusters, leading to reduced catalytic activity over time. To find a solution to this problem, we modelled the interaction of group 4A metal porphyrins (germanium (II) porphyrin (GePor), tin (II) porphyrin (SnPor) and lead (II) porphyrin (PbPor)) with platinum (Pt) using density functional theory. We showed that platinum can bond strongly on both germanium porphyrin and tin porphyrin. More importantly, valence Pt d-orbital characteristics dominate their HOMO and HOMO-1. Our study indicates that dispersing Pt as individual atoms on a SnPor and GePor surface is a good way to minimize platinum load in carbon-based reduction catalysts for reactions involving mainly the HOMO and HOMO-1 of Pt, of which the oxygen reduction reaction in fuel cells is an example.

  12. Induction of protein crystallization by platinum nanoparticles

    NASA Astrophysics Data System (ADS)

    Takeda, Yoshihiro; Mafuné, Fumitaka

    2016-03-01

    We have investigated effects of platinum nanoparticles (PtNPs) on protein crystal nucleation. The presence of PtNPs increased the number of crystals in a crystallization solution, indicating that the PtNPs have the ability to promote the crystal nucleation. Dynamic light scattering measurements revealed that the PtNP gathers more than 10 lysozyme molecules around it to form an embryonic complex of PtNP and lysozyme. Zeta potential measurements revealed that the charges of the lysozyme molecules were reduced by delocalization of their charges in the complex. As a result, the energy barrier of association between the complexes is reduced, followed by the nucleation.

  13. Impedance spectra of polypyrrole coated platinum electrodes.

    PubMed

    Onnela, Niina; Savolainen, Virpi; Hiltunen, Maiju; Kellomäki, Minna; Hyttinen, Jari

    2013-01-01

    Polypyrrole (PPy) coated electrodes may provide new solutions to increase the charge injection capacity and biocompatibility of metal electrodes in e.g., neural stimulus applications. In this study, electrical impedance spectra of PPy coated platinum (Pt) electrodes having three different coating thicknesses were measured and modeled. A suitable equivalent electrical circuit providing the material characteristics was chosen and the impedance data was analyzed using the model and data fitting. The modeled parameter values of different coating thicknesses were compared and our results demonstrated the changes in charge transfer properties and mechanisms of thin and thick PPy film coatings. PMID:24109743

  14. Computational Study of Platinum Group Superalloys

    NASA Astrophysics Data System (ADS)

    Popoola, A. I.; Lowther, J. E.

    2014-02-01

    Various properties of substitutional alloys formed from aluminium and the platinum group metals (PGMs) are examined using density functional (D-F) theory and show strong variations depending on metal type. A similar pattern for the binary alloys is observed using molecular dynamics modeling employing Sutton Chen potentials. All results suggest that several of the PGMs could have superior properties to the presently used Ni3Al alloy for high temperature applications. Some phases are predicted to be stable with extremely high melting temperatures (MTs).

  15. Response time correlations for platinum resistance thermometers

    NASA Technical Reports Server (NTRS)

    Pandey, D. K.; Ash, R. L.; Dillon-Townes, L. A.

    1985-01-01

    The 'plunge method' recommended by ASTM has been used to determine the time constant of 100-ohm platinum resistance thermometers (PRT) considered for use in the National Transonic Facility. It is shown that the response time of ventilated PRT can be correlated with the reciprocal of the heat transfer coefficient in a given field. Universal correlations are established for the 100- and 1000-ohm PRT with uncertainties of 20 and 30 percent, respectively. The correlations are found to be consistent with the uncertainty involved in heat transfer correlations available in the literature and are recommended for use in flowing liquids and gases.

  16. Chemical crowd control agents.

    PubMed

    Menezes, Ritesh G; Hussain, Syed Ather; Rameez, Mansoor Ali Merchant; Kharoshah, Magdy A; Madadin, Mohammed; Anwar, Naureen; Senthilkumaran, Subramanian

    2016-03-01

    Chemical crowd control agents are also referred to as riot control agents and are mainly used by civil authorities and government agencies to curtail civil disobedience gatherings or processions by large crowds. Common riot control agents used to disperse large numbers of individuals into smaller, less destructive, and more easily controllable numbers include chloroacetophenone, chlorobenzylidenemalononitrile, dibenzoxazepine, diphenylaminearsine, and oleoresin capsicum. In this paper, we discuss the emergency medical care needed by sufferers of acute chemical agent contamination and raise important issues concerning toxicology, safety and health. PMID:26658556

  17. Platinum adlayered ruthenium nanoparticles, method for preparing, and uses thereof

    DOEpatents

    Tong, YuYe; Du, Bingchen

    2015-08-11

    A superior, industrially scalable one-pot ethylene glycol-based wet chemistry method to prepare platinum-adlayered ruthenium nanoparticles has been developed that offers an exquisite control of the platinum packing density of the adlayers and effectively prevents sintering of the nanoparticles during the deposition process. The wet chemistry based method for the controlled deposition of submonolayer platinum is advantageous in terms of processing and maximizing the use of platinum and can, in principle, be scaled up straightforwardly to an industrial level. The reactivity of the Pt(31)-Ru sample was about 150% higher than that of the industrial benchmark PtRu (1:1) alloy sample but with 3.5 times less platinum loading. Using the Pt(31)-Ru nanoparticles would lower the electrode material cost compared to using the industrial benchmark alloy nanoparticles for direct methanol fuel cell applications.

  18. EPM Fine-Disperse Platinum Coating on Powder Carriers

    NASA Astrophysics Data System (ADS)

    Serga, V.; Kulikova, L.; Cvetkov, A.; Krumina, A.

    2012-08-01

    In the reported investigation the extractive-pyrolytic method of fine-disperse platinum coating on powder carriers was applied. Nanopowders of Al2O3, γ- AlO(OH), Y2O3, CeO2, SiO2 were used as carriers. Investigations on the effect of synthesis parameters on the mean size of platinum crystallites in the produced composites (metal content 4.8 wt%) have revealed that the increase of the pyrolysis temperature, annealing period, metal concentration in the precursor [(C8H17)3NH]2PtCI6 in toluene as well as the decrease of the specific surface area result in growth of the mean size of platinum crystallites. Microscopic studies show the formation of platinum spherical particles sized 5 to 35 nm as a results of the pyrolysis of the platinum-containing precursor in a water-soluble carrier (fine-disperse NaCl).

  19. Squalamine treatment of human tumors in nu/nu mice enhances platinum-based chemotherapies.

    PubMed

    Williams, J I; Weitman, S; Gonzalez, C M; Jundt, C H; Marty, J; Stringer, S D; Holroyd, K J; Mclane, M P; Chen, Q; Zasloff, M; Von Hoff, D D

    2001-03-01

    Squalamine, an antiangiogenic aminosterol, is presently undergoing Phase II clinical trials in cancer patients. To broaden our understanding of the clinical potential for squalamine, this agent was evaluated in nu/nu mouse xenograft models using the chemoresistant MV-522 human non-small cell lung carcinoma and the SD human neuroblastoma lines. Squalamine was studied alone and in combination with either cisplatin or paclitaxel plus carboplatin. Squalamine alone produced a modest MV-522 tumor growth inhibition (TGI) and yielded a TGI with cisplatin that was better than cisplatin alone. Squalamine also significantly enhanced the activity of paclitaxel/carboplatin combination therapy in the MV-522 tumor model. Squalamine similarly improved the effectiveness of cisplatin in producing TGI when screened against the SD human neuroblastoma xenograft. Xenograft tumor shrinkage was seen for the MV-522 tumor in combination treatments including squalamine, whereas no tumor shrinkage was seen when squalamine was omitted from the treatment regimen. To gain a greater understanding of the mechanism by which squalamine inhibited tumor growth in the xenograft studies, in vitro experiments were carried out with vascular endothelial growth factor-stimulated human umbilical vein endothelial cells in culture exposed to squalamine. Squalamine treatment was found to retard two cellular events necessary for angiogenesis, inducing disorganization of F-actin stress fibers and causing a concomitant reduction of detectable cell the surface molecular endothelial cadherin (VE-cadherin). We propose that the augmentation by squalamine of cytotoxicity from platinum-based therapies is attributable to interference by squalamine with the ability of stimuli to promote endothelial cell movement and cell-cell communication necessary for growth of new blood vessels in xenografts after chemotherapeutic injury to the tumor. PMID:11297269

  20. Real-world hospital costs for nonchemotherapy drugs and nondrug care associated with platinum-based doublets in the first-line setting for advanced nonsquamous non-small-cell lung cancer in Chinese patients: a retrospective cohort study

    PubMed Central

    Chen, Jianhua; Wu, Shengqi; Hu, Chenping; Yang, Yicheng; Rajan, Narayan; Chen, Yun; Yang, Canjuan; Li, Jianfeng; Chen, Wendong

    2016-01-01

    Objective The objective of this study was to compare hospital costs per treatment cycle (HCTC) for nonchemotherapy drugs and nondrug care associated with platinum-based doublets in the first-line setting for advanced nonsquamous non-small-cell lung cancer (AdvNS-NSCLC) in Chinese patients. Methods Patients receiving platinum-based doublets in the first-line setting for AdvNS-NSCLC from 2010 to 2012 in two Chinese tertiary hospitals were identified to create the retrospective study cohort. Propensity score methods were used to create matched treatment groups for head-to-head comparisons on HCTC between pemetrexed–platinum and other platinum-based doublets. Multiple linear regression analyses were performed to rank studied platinum-based doublets for their associations with the log10 scale of HCTC for nonchemotherapy drugs and nondrug care. Results Propensity score methods created matched treatment groups for pemetrexed–platinum versus docetaxel–platinum (61 pairs), paclitaxel–platinum (39 pairs), gemcitabine–platinum (93 pairs), and vinorelbine–platinum (73 pairs), respectively. Even though the log10 scale of HCTC for nonchemotherapy drugs and nondrug care associated with pemetrexed–platinum was ranked lowest in all patients (coefficient −0.174, P=0.015), which included patients experiencing any hematological adverse events (coefficient −0.199, P=0.013), neutropenia (coefficient −0.426, P=0.021), or leukopenia (coefficient −0.406, P=0.001), pemetrexed–platinum had the highest total HCTC (median difference from RMB 1,692 to RMB 7,400, P<0.001) among platinum-based doublets because of its higher drug acquisition costs (median difference from RMB 4,636 to RMB 7,332, P<0.001). Conclusion Among Chinese patients receiving platinum-based doublets in the first-line setting for AdvNS-NSCLC, the higher acquisition costs for nonplatinum cytotoxic drugs associated with pemetrexed–platinum could be partially offset by its significantly lower hospital

  1. The effects of selected drugs, including chlorpromazine and non-steroidal anti-inflammatory agents, on polyclonal IgG synthesis and interleukin 1 production by human peripheral blood mononuclear cells in vitro.

    PubMed

    Martinez, F; Coleman, J W

    1989-05-01

    We tested a range of drugs for their effects on in vitro polyclonal IgG synthesis by human peripheral blood mononuclear cells (PBMC) stimulated with the lectin pokeweed mitogen (PWM). The test drugs were selected on the basis of reported disruptive effects on immune function in vivo. IgG production between day 4 and days 7 or 8 of culture was measured by biotin-streptavidin sandwich ELISA. The anti-psychotic agent chlorpromazine (0.55-1.7 microM) enhanced IgG synthesis to approximately double control levels. In contrast, the non-steroidal anti-inflammatory drugs (NSAIDs) indomethacin, piroxicam, ibuprofen and aspirin inhibited IgG synthesis by up to 50%, with a rank order of potency that reflects their activity as inhibitors of cyclo-oxygenase. Phenytoin, procainamide, propylthiouracil, methimazole, D-penicillamine and D-penicillamine-L-cysteine all failed to modulate IgG synthesis at non-toxic concentrations. The potentiation and inhibition of IgG synthesis by chlorpromazine and indomethacin, respectively, was observed only when the drug was present during the first 24 h of culture. Neither chlorpromazine nor indomethacin, at non-toxic concentrations, affected PHA- and PWM-stimulated proliferation of PBMC. In addition, chlorpromazine, indomethacin and piroxicam, at concentrations which produced maximal modulation of IgG synthesis, and D-penicillamine and D-penicillamine-L-cysteine at 10 microM failed to influence production of interleukin-1-like activity. We conclude that chlorpromazine and NSAIDs, although they exert opposite effects on IgG synthesis, act at an early stage of B cell differentiation that appears to be independent of interleukin 1 synthesis and early proliferative events. PMID:2788047

  2. HIPEC ROC I: a phase I study of cisplatin administered as hyperthermic intraoperative intraperitoneal chemoperfusion followed by postoperative intravenous platinum-based chemotherapy in patients with platinum-sensitive recurrent epithelial ovarian cancer.

    PubMed

    Zivanovic, Oliver; Abramian, Alina; Kullmann, Maximilian; Fuhrmann, Christine; Coch, Christoph; Hoeller, Tobias; Ruehs, Hauke; Keyver-Paik, Mignon Denise; Rudlowski, Christian; Weber, Stefan; Kiefer, Nicholas; Poelcher, Martin L; Thiesler, Thore; Rostamzadeh, Babak; Mallmann, Michael; Schaefer, Nico; Permantier, Maryse; Latten, Sandra; Kalff, Joerg; Thomale, Juergen; Jaehde, Ulrich; Kuhn, Walther C

    2015-02-01

    This phase I study tested the safety, feasibility, pharmacokinetics and pharmacodynamics of cisplatin administered as hyperthermic intraoperative intraperitoneal chemoperfusion (HIPEC) in patients with platinum-sensitive recurrent epithelial ovarian cancer (EOC) undergoing secondary cytoreductive surgery followed by postoperative platinum-based intravenous chemotherapy. Twelve patients with operable, recurrent platinum-sensitive EOC (recurrence ≥6 months after first-line therapy) were included according to the classical 3+3 dose-escalation design at three dose levels-60, 80 and 100 mg/m(2). After surgical cytoreduction, a single dose of cisplatin was administered via HIPEC for 90 min at 41-43°C. Postoperatively, all patients were treated with standard intravenous platinum-based combination chemotherapy. One of six patients experienced a dose-limiting toxicity (grade 3 renal toxicity) at a dose of 100 mg/m(2). The remaining five patients treated with 100 mg/m(2) tolerated their treatment well. The recommended phase II dose was established at 100 mg/m(2). The mean peritoneal-to-plasma AUC ratio was 19·5 at the highest dose level. Cisplatin-induced DNA adducts were confirmed in tumor samples. Common postoperative grade 1-3 toxicities included fatigue, postoperative pain, nausea, and surgical site infection. The ability to administer standard intravenous platinum-based chemotherapy after HIPEC was uncompromised. Cisplatin administered as HIPEC at a dose of 100 mg/m(2) has an acceptable safety profile in selected patients undergoing secondary cytoreductive surgery for platinum-sensitive recurrent EOC. Favorable pharmacokinetic and pharmacodynamic properties of HIPEC with cisplatin were confirmed at all dose levels, especially at 100 mg/m(2). The results are encouraging to determine the efficacy of HIPEC as a complementary treatment in patients with EOC. PMID:24895230

  3. Ozone enhancement of platinum asthma in a primate model

    SciTech Connect

    Biagini, R.E.; Moorman, W.J.; Lewis, T.R.; Bernstein, I.L.

    1986-10-01

    Three groups of adult male cynomolgus monkeys (Macaca fascicularis) were exposed to either 200 micrograms/m/sup 3/ ammonium hexachloroplatinate ((NH/sub 4/)2PtCl/sub 6/), 200 micrograms (NH/sub 4/)2PtCl/sub 6/ concurrently with 1 ppm ozone (O/sub 3/), or to 1 ppm O/sub 3/ only. The animals were exposed by inhalation for 6 h per day, 5 days per week for 12 wk. The experimental design included methacholine preexposure and Na2PtCl/sub 6/ bronchoprovocation challenge evaluations, Na2PtCl/sub 6/ threshold skin tests, and sera for analyses of antibodies. Two weeks after the 12-wk exposures, these same indices were reevaluated. Baseline pulmonary function was not significantly affected by the exposure regimens; however, the combination of exposure to O/sub 3/ and (NH/sub 4/)2PtCl/sub 6/ significantly reduced the concentration of platinum (Pt) salt and methacholine necessary to increase average pulmonary flow resistance (RL) 200% (EC200 RL). Ozone or Pt exposure alone had no significant effect on these parameters. Platinum and methacholine EC200 RL values were highly correlated for both Pt-exposed groups after exposure. These data indicated that combined O/sub 3/ and Pt exposure significantly increased specific (Pt) and nonspecific (methacholine) bronchial hyperreactivity more often than did exposure to either O/sub 3/ or the Pt salt alone. Combined O/sub 3/ plus Pt exposure also significantly increases the incidence of positive Pt skin tests when compared with the other exposure groups. Similar to the human experience, radioallergosorbent testing (RAST) for Pt-specific antibodies was not as sensitive as direct skin testing in identifying allergic persons.

  4. Therapeutic gold, silver, and platinum nanoparticles.

    PubMed

    Yamada, Miko; Foote, Matthew; Prow, Tarl W

    2015-01-01

    There are an abundance of nanoparticle technologies being developed for use as part of therapeutic strategies. This review focuses on a narrow class of metal nanoparticles that have therapeutic potential that is a consequence of elemental composition and size. The most widely known of these are gold nanoshells that have been developed over the last two decades for photothermal ablation in superficial cancers. The therapeutic effect is the outcome of the thickness and diameter of the gold shell that enables fine tuning of the plasmon resonance. When these metal nanoparticles are exposed to the relevant wavelength of light, their temperature rapidly increases. This in turn induces a localized photothermal ablation that kills the surrounding tumor tissue. Similarly, gold nanoparticles have been developed to enhance radiotherapy. The high-Z nature of gold dramatically increases the photoelectric cross-section. Thus, the photoelectric effects are significantly increased. The outcome of these interactions is enhanced tumor killing with lower doses of radiation, all while sparing tissue without gold nanoparticles. Silver nanoparticles have been used for their wound healing properties in addition to enhancing the tumor-killing effects of anticancer drugs. Finally, platinum nanoparticles are thought to serve as a reservoir for platinum ions that can induce DNA damage in cancer cells. The future is bright with the path to clinical trials is largely cleared for some of the less complex therapeutic metal nanoparticle systems. PMID:25521618

  5. State-of-the-Art Treatment and Novel Agents in Local and Distant Recurrences of Cervical Cancer.

    PubMed

    Tempfer, Clemens B; Beckmann, Matthias W

    2016-01-01

    Depending on the stage at initial presentation, cervical cancer will recur in 25-61% of women. Typical manifestations of recurrent cervical cancer include the central pelvis and the pelvic side walls as well as retroperitoneal lymph node basins in the pelvis and the para-aortic region, and - more rarely - supraclavicular lymph nodes. There are no typical symptoms of recurrent cervical cancer. Women with suspected recurrence after cervical cancer based on gynecological examination or organ-specific symptoms must undergo imaging studies and - if technically feasible - biopsy with histological verification, especially in cases of distant metastases, in order to rule out a second primary. Radiotherapy-naïve women should be treated with salvage radiochemotherapy with curative intention. For women with previous radiotherapy, surgery in the form of hysterectomy, local resection, or pelvic exenteration is the treatment of choice. Pelvic exenteration can lead to cure in selected patients, but at the price of a high rate of complications and significant morbidity and mortality. If complete surgical resection is not feasible or if the woman is not a candidate for surgery, chemotherapy with palliative intent should be offered. Patients with recurrent disease outside the pelvis are candidates for systemic chemotherapy. Several agents have shown to be active in this situation, either in single-agent or combination regimens. Platinum-containing regimens have a superior efficacy over non-platinum regimens and bevacizumab may be added to chemotherapy. PMID:27614445

  6. Evaluation tests of platinum resistance thermometers for a cryogenic wind tunnel application

    NASA Technical Reports Server (NTRS)

    Germain, E. F.; Compton, E. C.

    1984-01-01

    Thirty-one commercially designed platinum resistance thermometers were evaluated for applicability to stagnation temperature measurements between -190 C and +65 C in the Langley Research Center's National Transonic Facility. Evaluation tests included X-ray shadowgraphs, calibrations before and after aging, and time constant measurements. Two wire-wound low thermal mass probes of a conventional design were chosen as most suitable for this cryogenic wind tunnel application.

  7. Core-Protected Platinum Monolayer Shell High-Stability Electrocatalysts for Fuel-Cell Cathodes

    SciTech Connect

    K Sasaki; H Naohara; Y Cai; Y Choi; P Liu; M Vukmirovic; J Wang; R Adzic

    2011-12-31

    Platinum monolayers can act as shells for palladium nanoparticles to lead to electrocatalysts with high activities and an ultralow platinum content, but high platinum utilization. The stability derives from the core protecting the shell from dissolution. In fuel-cell tests, no loss of platinum was observed in 200,000 potential cycles, whereas loss of palladium was significant.

  8. Core-Protected Platinum Monolayer Shell High-Stability Electrocatalysts for Fuel-Cell Cathodes

    SciTech Connect

    Adzic, R.R.; Sasaki, K.; Naohara, H.; Cai, Y.; Choi, Y.M.; Liu, P.; Vukmirovic, M.B.; Wang, J.X.

    2010-11-08

    More than skin deep: Platinum monolayers can act as shells for palladium nanoparticles to lead to electrocatalysts with high activities and an ultralow platinum content, but high platinum utilization. The stability derives from the core protecting the shell from dissolution. In fuel-cell tests, no loss of platinum was observed in 200?000 potential cycles, whereas loss of palladium was significant.

  9. Platinum-Tin Nano-Catalysts Supported on Alumina for Direct Dehydrogenation of n-Butane.

    PubMed

    Lee, Jong Kwon; Seo, Hyun; Hong, Ung Gi; Park, Gle; Yoo, Yeonshick; Lee, Jinsuk; Chang, Hosik; Song, In Kyu

    2015-10-01

    Al2O3 supports were prepared by a precipitation method using various basic solutions (NaOH, KOH, NH4OH, and Na2CO3) as precipitation agents, and Pt/Sn/Al2O3 nano-catalysts were then prepared by a sequential impregnation method. The prepared catalysts were applied to the direct dehydrogenation of n-butane to n-butenes and 1,3-butadiene. The effect of precipitation agents on the physicochemical properties and catalytic activities of Pt/Sn/Al2O3 nano-catalysts in the direct dehydrogenation of n-butane was investigated. Catalytic performance of Pt/Sn/Al2O3 nano-catalysts decreased in order of Pt/Sn/Al2O3 (NaOH) > Pt/Sn/Al2O3 (KOH) > Pt/Sn/Al2O3 (NH4OH) > Pt/Sn/Al2O3 (Na2CO3). Among the catalysts tested, Pt/Sn/Al2O3 (NaOH) nano-catalyst showed the best catalytic performance in terms of yield for total dehydrogenation products (TDP, n-butenes and 1,3-butadiene). Hydrogen chemisorption experiments revealed that platinum surface area of the catalyst was closely related to the catalytic performance. Yield for TDP increased with increasing platinum surface area of the catalyst. PMID:26726508

  10. A novel electroless method to prepare a platinum electrocatalyst on diamond for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Lyu, Xiao; Hu, Jingping; Foord, John S.; Wang, Qiang

    2013-11-01

    A novel electroless deposition method was demonstrated to prepare a platinum electrocatalyst on boron doped diamond (BDD) substrates without the need for pre-activation. This green method addresses the uniformity and particle size issues associated with electrodeposition and circumvents the pre-activation procedure which is necessary for conventional electroless deposition. The inert BDD substrate formed a galvanic couple with an iron wire, to overcome the activation barrier associated with conventional electroless deposition on diamond, leading to the formation of Pt nanoparticles on the electrode surface in a galvanic process coupled to a chemical process. When sodium hypophosphite was employed as the reducing agent to drive the electroless reaction Pt deposits which were contaminated with iron and phosphorus resulted. In contrast, the reducing agent ascorbic acid gave rise to high purity Pt nanoparticles. Optimal deposition conditions with respect to bath temperature, pH value and stabilizing additives are identified. Using this approach, high purity and uniformly distributed platinum nanoparticles are obtained on the diamond electrode surface, which demonstrate a high electrochemical activity towards methanol oxidation.

  11. A novel platinum chromium everolimus-eluting stent for the treatment of coronary artery disease

    PubMed Central

    Bennett, Johan; Dubois, Christophe

    2013-01-01

    The development of coronary stents represents a major step forward in the treatment of obstructive coronary artery disease since the introduction of percutaneous coronary intervention. The initial enthusiasm for bare metal stents was, however, tempered by a significant incidence of in-stent restenosis, the manifestation of excessive neointima hyperplasia within the stented vessel segment, ultimately leading to target vessel revascularization. Later, drug-eluting stents, with controlled local release of antiproliferative agents, consistently reduced this need for repeat revascularization. In turn, the long-term safety of first-generation drug-eluting stents was brought into question with the observation of an increased incidence of late stent thrombosis, often presenting as myocardial infarction or sudden death. Since then, new drugs, polymers, and platforms for drug elution have been developed to improve stent safety and preserve efficacy. Development of a novel platinum chromium alloy with high radial strength and high radiopacity has enabled the design of a new, thin-strut, flexible, and highly trackable stent platform, while simultaneously improving stent visibility. Significant advances in polymer coating, serving as a drug carrier on the stent surface, and in antiproliferative agent technology have further improved the safety and clinical performance of newer-generation drug-eluting stents. This review will provide an overview of the novel platinum chromium everolimus-eluting stents that are currently available. The clinical data from major clinical trials with these devices will be summarized and put into perspective. PMID:23818756

  12. Sustained platelet-sparing effect of weekly low dose paclitaxel allows effective, tolerable delivery of extended dose dense weekly carboplatin in platinum resistant/refractory epithelial ovarian cancer

    PubMed Central

    2011-01-01

    Background Platinum agents have shown demonstrable activity in the treatment of patients with platinum resistant, recurrent ovarian cancer when delivered in a "dose-dense" fashion. However, the development of thrombocytopenia limits the weekly administration of carboplatin to no greater than AUC 2. Paclitaxel has a well-described platelet sparing effect however its use to explicitly provide thromboprotection in the context of dose dense carboplatin has not been explored. Methods We treated seven patients with platinum resistant ovarian cancer who had previously received paclitaxel or who had developed significant peripheral neuropathy precluding the use of further full dose weekly paclitaxel. Results We were able to deliver carboplatin AUC 3 and paclitaxel 20 mg/m2 with no thrombocytopenia or worsening of neuropathic side-effects, and with good activity. Conclusions We conclude that this regimen may be feasible and active, and could be formally developed as a "platinum-focussed dose-dense scaffold" into which targeted therapies that reverse platinum resistance can be incorporated, and merits further evaluation. PMID:21745358

  13. A compendium of causative agents of occupational asthma

    PubMed Central

    2013-01-01

    Objective The objective is to provide an evidence-based compendium of allergenic and irritant agents that are known to cause occupational asthma in order to improve diagnostics and disease management. Methods Two previously published reviews from our group utilized database searches to identify studies which were then rated according to the Scottish Intercollegiate Guideline Network (SIGN) grading system. The evidence level for each causative agent or worksite was graded using the Royal College of General Practitioners (RCGP) three-star system. Results Approximately 3,000 relevant papers were identified, which covered 372 different causes of allergic and 184 different causes of irritant occupational asthma. The highest level achieved using the SIGN grading system was 2++, indicating a high quality study with a very low risk of confounding or bias and a high probability of a causal relationship. Using the modified RCGP three-star grading system, the strongest evidence of association with an individual agent or worksite ('***') was found for exposure to laboratory animals. Associations with moderate evidence level (‘**’) were obtained for a) the allergenic agents or worksites: alpha-amylase from Aspergillus oryzae, various enzymes from Bacillus subtilis, papain, bakeries, western red cedar, latex, psyllium, storage mites, rat, carmine, egg proteins, Atlantic salmon, fishmeal, Norway lobster, prawn, snow crab, seafood, trout and turbot, reactive dyes, b) the irritant agents or worksites: benzene-1,2,4-tricarboxylic acid, 1,2- anhydride [trimellitic anhydride], chlorine, cobalt, cement, environmental tobacco smoke, grain, welding fumes, construction work, swine confinement, World Trade Center disaster 2001, and c) agents or worksites causing allergic as well as irritant occupational asthma, included farming, poultry confinement, various isocyanates and platinum salts. A low evidence level (RCGP) was obtained for 84 agents or worksites (42 from each group

  14. Gallium a unique anti-resorptive agent in bone: Preclinical studies on its mechanisms of action

    SciTech Connect

    Bockman, R.; Adelman, R.; Donnelly, R.; Brody, L.; Warrell, R. ); Jones, K.W. )

    1990-01-01

    The discovery of gallium as a new and unique agent for the treatment of metabolic bone disorders was in part fortuitous. Gallium is an exciting new therapeutic agent for the treatment of pathologic states characterized by accelerated bone resorption. Compared to other therapeutic metal compounds containing platinum or germanium, gallium affects its antiresorptive action without any evidence of a cytotoxic effect on bone cells. Gallium is unique amongst all therapeutically available antiresorptive agents in that it favors bone formation. 18 refs., 1 fig.

  15. Coatings of Different Carbon Nanotubes on Platinum Electrodes for Neuronal Devices: Preparation, Cytocompatibility and Interaction with Spiral Ganglion Cells

    PubMed Central

    Schwarz, Hans-Christoph; Kranz, Katharina; Motz, Damian; Vogt, Carla; Lenarz, Thomas; Warnecke, Athanasia; Behrens, Peter

    2016-01-01

    Cochlear and deep brain implants are prominent examples for neuronal prostheses with clinical relevance. Current research focuses on the improvement of the long-term functionality and the size reduction of neural interface electrodes. A promising approach is the application of carbon nanotubes (CNTs), either as pure electrodes but especially as coating material for electrodes. The interaction of CNTs with neuronal cells has shown promising results in various studies, but these appear to depend on the specific type of neurons as well as on the kind of nanotubes. To evaluate a potential application of carbon nanotube coatings for cochlear electrodes, it is necessary to investigate the cytocompatibility of carbon nanotube coatings on platinum for the specific type of neuron in the inner ear, namely spiral ganglion neurons. In this study we have combined the chemical processing of as-delivered CNTs, the fabrication of coatings on platinum, and the characterization of the electrical properties of the coatings as well as a general cytocompatibility testing and the first cell culture investigations of CNTs with spiral ganglion neurons. By applying a modification process to three different as-received CNTs via a reflux treatment with nitric acid, long-term stable aqueous CNT dispersions free of dispersing agents were obtained. These were used to coat platinum substrates by an automated spray-coating process. These coatings enhance the electrical properties of platinum electrodes, decreasing the impedance values and raising the capacitances. Cell culture investigations of the different CNT coatings on platinum with NIH3T3 fibroblasts attest an overall good cytocompatibility of these coatings. For spiral ganglion neurons, this can also be observed but a desired positive effect of the CNTs on the neurons is absent. Furthermore, we found that the well-established DAPI staining assay does not function on the coatings prepared from single-wall nanotubes. PMID:27385031

  16. Coatings of Different Carbon Nanotubes on Platinum Electrodes for Neuronal Devices: Preparation, Cytocompatibility and Interaction with Spiral Ganglion Cells.

    PubMed

    Burblies, Niklas; Schulze, Jennifer; Schwarz, Hans-Christoph; Kranz, Katharina; Motz, Damian; Vogt, Carla; Lenarz, Thomas; Warnecke, Athanasia; Behrens, Peter

    2016-01-01

    Cochlear and deep brain implants are prominent examples for neuronal prostheses with clinical relevance. Current research focuses on the improvement of the long-term functionality and the size reduction of neural interface electrodes. A promising approach is the application of carbon nanotubes (CNTs), either as pure electrodes but especially as coating material for electrodes. The interaction of CNTs with neuronal cells has shown promising results in various studies, but these appear to depend on the specific type of neurons as well as on the kind of nanotubes. To evaluate a potential application of carbon nanotube coatings for cochlear electrodes, it is necessary to investigate the cytocompatibility of carbon nanotube coatings on platinum for the specific type of neuron in the inner ear, namely spiral ganglion neurons. In this study we have combined the chemical processing of as-delivered CNTs, the fabrication of coatings on platinum, and the characterization of the electrical properties of the coatings as well as a general cytocompatibility testing and the first cell culture investigations of CNTs with spiral ganglion neurons. By applying a modification process to three different as-received CNTs via a reflux treatment with nitric acid, long-term stable aqueous CNT dispersions free of dispersing agents were obtained. These were used to coat platinum substrates by an automated spray-coating process. These coatings enhance the electrical properties of platinum electrodes, decreasing the impedance values and raising the capacitances. Cell culture investigations of the different CNT coatings on platinum with NIH3T3 fibroblasts attest an overall good cytocompatibility of these coatings. For spiral ganglion neurons, this can also be observed but a desired positive effect of the CNTs on the neurons is absent. Furthermore, we found that the well-established DAPI staining assay does not function on the coatings prepared from single-wall nanotubes. PMID:27385031

  17. Glioblastoma Treatment: Bypassing the Toxicity of Platinum Compounds by Using Liposomal Formulation and Increasing Treatment Efficiency With Concomitant Radiotherapy

    SciTech Connect

    Charest, Gabriel; Sanche, Leon; Fortin, David; Mathieu, David; Paquette, Benoit

    2012-09-01

    Purpose: Treatments of glioblastoma with cisplatin or oxaliplatin only marginally improve the overall survival of patients and cause important side effects. To prevent adverse effects, improve delivery, and optimize the tumor response to treatment in combination with radiotherapy, a potential approach consists of incorporating the platinum agent in a liposome. Methods and Materials: In this study, cisplatin, oxaliplatin, carboplatin, Lipoplatin (the liposomal formulation of cisplatin), and Lipoxal (the liposomal formulation of oxaliplatin) were tested on F98 glioma orthotopically implanted in Fischer rats. The platinum compounds were administered by intracarotid infusion and were assessed for the ability to reduce toxicity, improve cancer cell uptake, and increase survival of animals when combined or not combined with radiotherapy. Results: The tumor uptake was 2.4-fold more important for Lipoxal than the liposome-free oxaliplatin. Lipoxal also improved the specificity of oxaliplatin as shown by a higher ratio of tumor to right hemisphere uptake. Surprisingly, Lipoplatin led to lower tumor uptake compared with cisplatin. However, Lipoplatin had the advantage of largely reducing the toxicity of cisplatin and allowed us to capitalize on the anticancer activity of this agent. Conclusion: Among the five platinum compounds tested, carboplatin showed the best increase in survival when combined with radiation for treatment of glioma implanted in Fischer rats.

  18. Electrochemical platinum coatings for improving performance of implantable microelectrode arrays.

    PubMed

    de Haro, C; Mas, R; Abadal, G; Muñoz, J; Perez-Murano, F; Dominguez, C

    2002-12-01

    The formation and properties of electrochemical platinum films grown on platinum contacts contained in implantable flexible microelectrodes were investigated. The resulting platinum deposits were obtained by applying cyclic voltammetry to baths containing concentrations around 70 mM of chloroplatinic acid. A pre-activation step was necessary before the platinum-electroplating step in order to achieve good adhesive properties. The benefits of this process were ascribed to higher corrosion resistance, lower impedance and improved adhesion to the sputtered platinum. These improvements can make the application of this electrochemical technique highly useful for increasing the lifetime of implantable microelectrode arrays, such as cuff structures (IEEE Trans. Biomed. Eng. 40 (1993) 640). These medical devices, obtained by semiconductor technology could be used for selective stimulation of nerve fascicles, although, poor long-term performance has been achieved with them. The dissolution rate for platinum thin-film microelectrodes under fixed corrosion test conditions was 38.8 ng/C. Lower rates were observed for electroplated microelectrodes, obtaining a dissolution rate of 7.8 ng/C under analogous experimental ageing conditions. The corrosion behaviour of the electroplated platinum during stimulation experimental conditions was estimated by electrochemical impedance spectroscopy. PMID:12322971

  19. Electron Beam Welder Used to Braze Sapphire to Platinum

    NASA Technical Reports Server (NTRS)

    Forsgren, Roger C.; Vannuyen, Thomas

    1998-01-01

    A new use for electron beam brazing was recently developed by NASA Lewis Research Center's Manufacturing Engineering Division. This work was done to fabricate a fiberoptic probe (developed by Sentec Corporation) that could measure high temperatures less than 600 deg C of vibrating machinery, such as in jet engine combustion research. Under normal circumstances, a sapphire fiber would be attached to platinum by a ceramic epoxy. However, no epoxies can adhere ceramic fibers to platinum under such high temperatures and vibration. Also, since sapphire and platinum have different thermal properties, the epoxy bond is subjected to creep over time. Therefore, a new method had to be developed that would permanently and reliably attach a sapphire fiber to platinum. Brazing a sapphire fiber to a platinum shell. The fiber-optic probe assembly consists of a 0.015-in.-diameter sapphire fiber attached to a 0.25-in.-long, 0.059-in.-diameter platinum shell. Because of the small size of this assembly, electron beam brazing was chosen instead of conventional vacuum brazing. The advantage of the electron beam is that it can generate a localized heat source in a vacuum. Gold reactive braze was used to join the sapphire fiber and the platinum. Consequently, the sapphire fiber was not affected by the total heat needed to braze the components together.

  20. Surface Analysis of 4-Aminothiophenol Adsorption at Polycrystalline Platinum Electrodes

    NASA Technical Reports Server (NTRS)

    Rosario-Castro, Belinda I.; Fachini, Estevao R.; Contes, Enid J.; Perez-Davis, Marla E.; Cabrera, Carlos R.

    2008-01-01

    Formation of self-assembled monolayer (SAM) of 4-aminothiophenol (4-ATP) on polycrystalline platinum electrodes has been studied by surface analysis and electrochemistry techniques. The 4-ATP monolayer was characterized by cyclic voltammetry (CV), Raman spectroscopy, reflection absorption infrared (RAIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) experiments give an idea about the packing quality of the monolayer. RAIR and Raman spectra for 4-ATP modified platinum electrodes showed the characteristic adsorption bands for neat 4-ATP indicating the adsorption of 4-ATP molecules on platinum surface. The adsorption on platinum was also evidenced by the presence of sulfur and nitrogen peaks by XPS survey spectra of the modified platinum electrodes. High resolution XPS studies and RAIR spectrum for platinum electrodes modified with 4-ATP indicate that molecules are sulfur-bonded to the platinum surface. The formation of S-Pt bond suggests that ATP adsorption gives up an amino terminated SAM. Thickness of the monolayer was evaluated via angle-resolved XPS (AR-XPS) analyses. Derivatization of 4-ATP SAM was performed using 16-Br hexadecanoic acid.

  1. Platinum coat color locus in the deer mouse.

    PubMed

    Dodson, K M; Dawson, W D; Van Ooteghem, S O; Cushing, B S; Haigh, G R

    1987-01-01

    Platinum coat color in the deer mouse, Peromyscus maniculatus, is an autosomal recessive trait marking a locus, pt, distinct from silver (si), albino (c), blonde (bl), brown (b), and agouti (a). Platinum deer mice are conspicuously pale, with light ears and tail stripe. The pewter trait is allelic with and phenotypically identical to platinum, and represents an independent recurrence of this mutant. The rate of recoveries of coat color mutations from wild deer mice is consistent with available data for recurring mutation rates balanced by strong selection against the recessive phenotype. PMID:3611714

  2. Bio-inspired routes for synthesizing efficient nanoscale platinum electrocatalysts

    SciTech Connect

    Cha, Jennifer N.; Wang, Joseph

    2014-08-31

    The overall objective of the proposed research is to use fundamental advances in bionanotechnology to design powerful platinum nanocrystal electrocatalysts for fuel cell applications. The new economically-viable, environmentally-friendly, bottom-up biochemical synthetic strategy will produce platinum nanocrystals with tailored size, shape and crystal orientation, hence leading to a maximum electrochemical reactivity. There are five specific aims to the proposed bio-inspired strategy for synthesizing efficient electrocatalytic platinum nanocrystals: (1) isolate peptides that both selectively bind particular crystal faces of platinum and promote the nucleation and growth of particular nanocrystal morphologies, (2) pattern nanoscale 2-dimensional arrays of platinum nucleating peptides from DNA scaffolds, (3) investigate the combined use of substrate patterned peptides and soluble peptides on nanocrystal morphology and growth (4) synthesize platinum crystals on planar and large-area carbon electrode supports, and (5) perform detailed characterization of the electrocatalytic behavior as a function of catalyst size, shape and morphology. Project Description and Impact: This bio-inspired collaborative research effort will address key challenges in designing powerful electrocatalysts for fuel cell applications by employing nucleic acid scaffolds in combination with peptides to perform specific, environmentally-friendly, simultaneous bottom-up biochemical synthesis and patterned assembly of highly uniform and efficient platinum nanocrystal catalysts. Bulk synthesis of nanoparticles usually produces a range of sizes, accessible catalytic sites, crystal morphologies, and orientations, all of which lead to inconsistent catalytic activities. In contrast, biological systems routinely demonstrate exquisite control over inorganic syntheses at neutral pH and ambient temperature and pressures. Because the orientation and arrangement of the templating biomolecules can be precisely

  3. Oxidation performance of platinum-clad Mo-47Re alloy

    NASA Technical Reports Server (NTRS)

    Clark, Ronald K.; Wallace, Terryl A.

    1994-01-01

    The alloy Mo-47Re has favorable mechanical properties at temperatures above 1400 C, but it undergoes severe oxidation when used in air with no protective coating. To shield the alloy from oxidation, platinum cladding has been evaluated. The unprotected alloy undergoes catastrophic oxidation under static and dynamic oxidation conditions. The platinum cladding provides good protection from static and dynamic oxidation for moderate times at 1260 C. Samples tested for longer times under static oxidation conditions experienced severe oxidation. The data suggest that oxidation results from the transport of oxygen through the grain boundaries and through the pinhole defects of the platinum cladding.

  4. Efficacy of pemetrexed plus platinum doublet chemotherapy as first-line treatment for advanced nonsquamous non-small-cell-lung cancer: a systematic review and meta-analysis

    PubMed Central

    Xiao, Huai-Qing; Tian, Rong-Hua; Zhang, Zhi-Hao; Du, Kai-Qi; Ni, Yi-Ming

    2016-01-01

    Purpose To assess the efficacy of pemetrexed plus platinum doublet chemotherapy as first-line treatment for advanced nonsquamous non-small-cell lung cancer (NSCLC) through a trial-level meta-analysis. Methods Trials published between 1990 and 2015 were identified by an electronic search of public databases (Medline, Embase, and Cochrane Library). All clinical studies were independently identified by two authors. Demographic data, treatment regimens, objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were extracted and analyzed using comprehensive meta-analysis software (version 2.0). Results A total of 2,551 patients with advanced nonsquamous NSCLC from ten trials were included for analysis: 1,565 patients were treated with pemetrexed plus platinum doublet chemotherapy and 986 with platinum plus other first-line chemotherapy. Pooled ORR for pemetrexed plus platinum chemotherapy was 37.8% (95% confidence interval [CI]: 31.7%–44.3%), with median PFS and OS of 5.7 and 16.05 months, respectively. When compared to other platinum-based doublet chemotherapies, the use of pemetrexed plus platinum chemotherapy significantly improved OS (hazard ratio [HR] =0.86, 95% CI: 0.77–0.97, P=0.01) but not PFS (HR =0.90, 95% CI: 0.80–1.01, P=0.084) in advanced nonsquamous NSCLC patients. Conclusion Pemetrexed plus platinum doublet regimen is an efficacious treatment for advanced nonsquamous NSCLC patients. Our findings support the use of pemetrexed plus platinum doublet regimen as first-line treatment in advanced nonsquamous NSCLC patients because of its potential survival benefits. PMID:27042115

  5. Biallelic Inactivation of BRCA2 in Platinum-sensitive Metastatic Castration-resistant Prostate Cancer.

    PubMed

    Cheng, Heather H; Pritchard, Colin C; Boyd, Thomas; Nelson, Peter S; Montgomery, Bruce

    2016-06-01

    Understanding the molecular underpinnings of sensitivity to specific therapies will advance the goal of precision medicine in prostate cancer (PCa). We identified three patients with metastatic castration-resistant PCa (mCRPC) who achieved an exceptional response to platinum chemotherapy (not first-line treatment for PCa), despite disease progression on prior standard therapies. Using targeted next-generation sequencing on the primary and metastatic tumors, we found that all three patients had biallelic inactivation of BRCA2, a tumor suppressor gene critical for homologous DNA repair. Notably, two had germline BRCA2 mutations, including a patient without compelling family history who was diagnosed at age 66 yr. The third patient had somatic BRCA2 homozygous copy loss. Biallelic BRCA2 inactivation in mCRPC warrants further exploration as a predictive biomarker for sensitivity to platinum chemotherapy. PMID:26724258

  6. Multistep electrochemical deposition of hierarchical platinum alloy counter electrodes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Junjun; Ma, Mingming; Tang, Qunwei; Yu, Liangmin

    2016-01-01

    The preferred platinum counter electrode (CE) has been a burden for commercialization of dye-sensitized solar cell (DSSC) due to high expense and chemical corrosion by liquid electrolyte. In the current study, we have successfully realized the multistep deposition of platinum alloy CEs including PtNi, PtFe, and PtCo for liquid-junction DSSC applications. The preliminary results demonstrate that the enhanced electrochemical activities are attributable to high charge-transfer ability and matching work functions of the PtM (M = Ni, Fe, Co) alloy CEs to redox potential of I-/I3- electrolyte. The resultant DSSCs yield impressive power conversion efficiencies of 8.65%, 7.48%, and 7.08% with PtNi, PtFe, and PtCo CEs, respectively. On behalf of the competitive reactions between transition metals with liquid electrolyte, the PtM alloy CEs display enhanced long-term stability.

  7. Biocompatibility of platinum-metallized silicone rubber: in vivo and in vitro evaluation.

    PubMed

    Vince, V; Thil, M A; Veraart, C; Colin, I M; Delbeke, J

    2004-01-01

    Silicone rubber is commonly used for biomedical applications, including implanted cuff electrodes for both recording and stimulation of peripheral nerves. This study was undertaken to evaluate the consequences of a new platinum metallization method on the biocompatibility of silicone rubber cuff electrodes. This method was introduced in order to allow the manufacture of spiral nerve cuff electrodes with a large number of contacts. The metallization process, implying silicone coating with poly(methyl methacrylate) (PMMA), its activation by an excimer laser and subsequent electroless metal deposition, led to a new surface microtexture. The neutral red cytotoxicity assay procedure was first applied in vitro on BALB/c 3T3 fibroblasts in order to analyze the cellular response elicited by the studied material. An in vivo assay was then performed to investigate the tissue reaction after chronic subcutaneous implantation of the metallized material. Results demonstrate that silicone rubber biocompatibility is not altered by the new platinum metallization method. PMID:15109096

  8. Agent oriented programming

    NASA Technical Reports Server (NTRS)

    Shoham, Yoav

    1994-01-01

    The goal of our research is a methodology for creating robust software in distributed and dynamic environments. The approach taken is to endow software objects with explicit information about one another, to have them interact through a commitment mechanism, and to equip them with a speech-acty communication language. System-level applications include software interoperation and compositionality. A government application of specific interest is an infrastructure for coordination among multiple planners. Daily activity applications include personal software assistants, such as programmable email, scheduling, and new group agents. Research topics include definition of mental state of agents, design of agent languages as well as interpreters for those languages, and mechanisms for coordination within agent societies such as artificial social laws and conventions.

  9. Docetaxel in combination with irinotecan (CPT-11) in platinum-resistant paclitaxel-pretreated ovarian cancer.

    PubMed

    Polyzos, Aristides; Kosmas, Christos; Toufexi, Helen; Malamos, Nicholas; Lagadas, Antonios; Kosmidis, Christos; Ginopoulos, Panagiotis; Ziras, Nicholas; Kandilis, Kostas; Georgoulias, Vassilis

    2005-01-01

    The role of combination chemotherapy regimens in the management of ovarian cancer patients with tumors resistant to platinum compounds has not yet been defined. This multicenter prospective phase II study evaluated the activity and toxicity of the docetaxel-plus-irinotecan combination in ovarian cancer patients whose tumors were resistant to platinum compounds and who had been exposed to paclitaxel. Treatment consisted of docetaxel 60 mg/m2 i.v. followed by irinotecan 200 mg/m2 i.v. both on day 1 followed by prophylactic recombinant human granulocyte-colony stimulating factor (rhG-CSF) support from days 2 to 6, every 3 weeks. Thirty-one patients were enrolled in the study. The median age was 60 years, and the median performance status (ECOG) was 1. Eight (26%) patients had primary tumors resistant to platinum, while the rest of the population had tumor recurrence within 6 months from the last cisplatin treatment. Four chemotherapy cycles per patient were administered, with the delivered dose intensity at 75% of the planned dose for both agents. Among 30 patients evaluable for response, there were 2 (7%) complete and 4 (14%) partial responses (overall response rate 20%; (95% confidence interval, CI, 11%-33%). Stable disease was recorded in 8 (28%) patients and progressive disease in 15 (51%). The median response duration was 4.5 months (range, 3-12), the median time to progression 5 months (range, 2-17) and the median survival 11 months (range, 1-40); the 1-year survival was almost 50%. Myelotoxicity was moderate, with grade 3 and 4 neutropenia occurring in 23% of the patients, grade 3-4 thrombocytopenia in 6% and febrile neutropenia in 13%. Grade 3 diarrhea was observed in 2% of the patients. There was one treatment-related death due to sepsis. In conclusion, the combination of docetaxel plus irinotecan with rhG-CSF support, appears to be a moderately effective regimen with acceptable toxicity for platinum-resistant, paclitaxel-pretreated ovarian cancer patients

  10. Pediatric Antifungal Agents

    PubMed Central

    Cohen-Wolkowiez, Michael; Moran, Cassandra; Benjamin, Daniel K.; Smith, P Brian

    2009-01-01

    Purpose of review In immunocompromised hosts, invasive fungal infections are common and fatal. In the past decade, the antifungal armamentarium against invasive mycoses has expanded greatly. The purpose of this report is to review the most recent literature addressing the use of antifungal agents in children. Recent findings Most studies evaluating the safety and efficacy of antifungal agents are limited to adults. However, important progress has been made in describing the pharmacokinetics and safety of newer antifungal agents in children, including the echinocandins. Summary Dosage guidelines for newer antifungal agents are currently based on adult and limited pediatric data. Because important developmental pharmacology changes occur throughout childhood impacting the pharmacokinetics of these agents, antifungal studies specifically designed for children are necessary. PMID:19741525

  11. Thermodynamic ground states of platinum metal nitrides

    SciTech Connect

    Aberg, D; Sadigh, B; Crowhurst, J; Goncharov, A

    2007-10-09

    We have systematically studied the thermodynamic stabilities of various phases of the nitrides of the platinum metal elements using density functional theory. We show that for the nitrides of Rh, Pd, Ir and Pt two new crystal structures, in which the metal ions occupy simple tetragonal lattice sites, have lower formation enthalpies at ambient conditions than any previously proposed structures. The region of stability can extend up to 17 GPa for PtN{sub 2}. Furthermore, we show that according to calculations using the local density approximation, these new compounds are also thermodynamically stable at ambient pressure and thus may be the ground state phases for these materials. We further discuss the fact that the local density and generalized gradient approximations predict different values of the absolute formation enthalpies as well different relative stabilities between simple tetragonal and the pyrite or marcasite structures.

  12. Platinum Nickel Nanowires as Methanol Oxidation Electrocatalysts

    SciTech Connect

    Alia, Shaun M.; Pylypenko, Svitlana; Neyerlin, Kenneth C.; Kocha, Shyam S.; Pivovar, Bryan S.

    2015-08-27

    We investigated platinum(Pt) nickel (Ni) nanowires (PtNiNWs) as methanol oxidation reaction (MOR) catalysts in rotating disk electrode (RDE) half-cells under acidic conditions. Pt-ruthenium (Ru) nanoparticles have long been the state of the art MOR catalyst for direct methanol fuel cells (DMFCs) where Ru provides oxophilic sites, lowering the potential for carbon monoxide oxidation and the MOR onset. Ru, however, is a precious metal that has long term durability concerns. Ni/Ni oxide species offer a potential to replace Ru in MOR electrocatalysis. PtNiNWs were investigated for MOR and oxygen annealing was investigated as a route to improve catalyst performance (mass activity 65% greater) and stability to potential cycling. Our results presented show that PtNiNWs offer significant promise in the area, but also result in Ni ion leaching that is a concern requiring further evaluation in fuel cells.

  13. Platinum dendritic nanoparticles with magnetic behavior

    NASA Astrophysics Data System (ADS)

    Li, Wenxian; Sun, Ziqi; Tian, Dongliang; Nevirkovets, Ivan P.; Dou, Shi-Xue

    2014-07-01

    Magnetic nanoparticles have attracted increasing attention for biomedical applications in magnetic resonance imaging, high frequency magnetic field hyperthermia therapies, and magnetic-field-gradient-targeted drug delivery. In this study, three-dimensional (3D) platinum nanostructures with large surface area that features magnetic behavior have been demonstrated. The well-developed 3D nanodendrites consist of plentiful interconnected nano-arms ˜4 nm in size. The magnetic behavior of the 3D dendritic Pt nanoparticles is contributed by the localization of surface electrons due to strongly bonded oxygen/Pluronic F127 and the local magnetic moment induced by oxygen vacancies on the neighboring Pt and O atoms. The magnetization of the nanoparticles exhibits a mixed paramagnetic and ferromagnetic state, originating from the core and surface, respectively. The 3D nanodendrite structure is suitable for surface modification and high amounts of drug loading if the transition temperature was enhanced to room temperature properly.

  14. Superconductivity observed in platinum-silicon interface

    SciTech Connect

    Kuo, Pai-Chia; Chen, Chun-Wei; Lee, Ku-Pin; Shiue, Jessie

    2014-05-26

    We report the discovery of superconductivity with an onset temperature of ∼0.6 K in a platinum-silicon interface. The interface was formed by using a unique focused ion beam sputtering micro-deposition method in which the energies of most sputtered Pt atoms are ∼2.5 eV. Structural and elemental analysis by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy reveal a ∼ 7 nm interface layer with abundant Pt, which is the layer likely responsible for the superconducting transport behavior. Similar transport behavior was also observed in a gold-silicon interface prepared by the same technique, indicating the possible generality of this phenomenon.

  15. Platinum dendritic nanoparticles with magnetic behavior

    SciTech Connect

    Li, Wenxian; Sun, Ziqi; Nevirkovets, Ivan P.; Dou, Shi-Xue; Tian, Dongliang

    2014-07-21

    Magnetic nanoparticles have attracted increasing attention for biomedical applications in magnetic resonance imaging, high frequency magnetic field hyperthermia therapies, and magnetic-field-gradient-targeted drug delivery. In this study, three-dimensional (3D) platinum nanostructures with large surface area that features magnetic behavior have been demonstrated. The well-developed 3D nanodendrites consist of plentiful interconnected nano-arms ∼4 nm in size. The magnetic behavior of the 3D dendritic Pt nanoparticles is contributed by the localization of surface electrons due to strongly bonded oxygen/Pluronic F127 and the local magnetic moment induced by oxygen vacancies on the neighboring Pt and O atoms. The magnetization of the nanoparticles exhibits a mixed paramagnetic and ferromagnetic state, originating from the core and surface, respectively. The 3D nanodendrite structure is suitable for surface modification and high amounts of drug loading if the transition temperature was enhanced to room temperature properly.

  16. Platinum Nickel Nanowires as Methanol Oxidation Electrocatalysts

    DOE PAGESBeta

    Alia, Shaun M.; Pylypenko, Svitlana; Neyerlin, Kenneth C.; Kocha, Shyam S.; Pivovar, Bryan S.

    2015-08-27

    We investigated platinum(Pt) nickel (Ni) nanowires (PtNiNWs) as methanol oxidation reaction (MOR) catalysts in rotating disk electrode (RDE) half-cells under acidic conditions. Pt-ruthenium (Ru) nanoparticles have long been the state of the art MOR catalyst for direct methanol fuel cells (DMFCs) where Ru provides oxophilic sites, lowering the potential for carbon monoxide oxidation and the MOR onset. Ru, however, is a precious metal that has long term durability concerns. Ni/Ni oxide species offer a potential to replace Ru in MOR electrocatalysis. PtNiNWs were investigated for MOR and oxygen annealing was investigated as a route to improve catalyst performance (mass activitymore » 65% greater) and stability to potential cycling. Our results presented show that PtNiNWs offer significant promise in the area, but also result in Ni ion leaching that is a concern requiring further evaluation in fuel cells.« less

  17. Thermodynamic ground states of platinum metal nitrides.

    PubMed

    Aberg, Daniel; Sadigh, Babak; Crowhurst, Jonathan; Goncharov, Alexander F

    2008-03-01

    The thermodynamic stabilities of various phases of the nitrides of the platinum-metal elements are systematically studied using density functional theory. It is shown that for the nitrides of Rh, Pd, Ir, and Pt two new crystal structures, in which the metal ions occupy simple tetragonal lattice sites, have lower formation enthalpies at ambient conditions than any previously proposed structures. The region of stability with respect to those structures extends to 17 GPa for PtN2. Calculations show that the PtN2 simple tetragonal structures at this pressure are thermodynamically stable also with respect to phase separation. The fact that the local density and generalized gradient approximations predict different values of the absolute formation enthalpies as well different relative stabilities between simple tetragonal and the pyrite or marcasite structures are further discussed. PMID:18352720

  18. Thermodynamic Ground States of Platinum Metal Nitrides

    NASA Astrophysics Data System (ADS)

    Åberg, Daniel; Sadigh, Babak; Crowhurst, Jonathan; Goncharov, Alexander F.

    2008-03-01

    The thermodynamic stabilities of various phases of the nitrides of the platinum-metal elements are systematically studied using density functional theory. It is shown that for the nitrides of Rh, Pd, Ir, and Pt two new crystal structures, in which the metal ions occupy simple tetragonal lattice sites, have lower formation enthalpies at ambient conditions than any previously proposed structures. The region of stability with respect to those structures extends to 17 GPa for PtN2. Calculations show that the PtN2 simple tetragonal structures at this pressure are thermodynamically stable also with respect to phase separation. The fact that the local density and generalized gradient approximations predict different values of the absolute formation enthalpies as well different relative stabilities between simple tetragonal and the pyrite or marcasite structures are further discussed.

  19. Platinum group nuggets in deep sea sediments

    NASA Technical Reports Server (NTRS)

    Brownlee, D. E.; Bates, B. A.; Wheelock, M. M.

    1984-01-01

    The existence of iron meteor oblation spheres in deep sea sediments was known for over a century. These spheres generally were believed to be composed of either pure magnetite and wustite or an oxide shell surrounding a NiFe metal core. A large number of 300 micron to 600 micron spheres found were pure oxide spheres, usually containing a solitary 10 micron platinum group nugget (pgn) composed almost entirely of group VIII metals. Twelve PGN's were analyzed and most had chondritic abundances with some depletions that correlate with element volatility. PGN formation by oxidation of a molten metal sphere entering the atmosphere cannot occur if the oxygen abundance in the atmosphere is less than half of its present value. The first appearance of PGN's in the geological record should mark when, in the Earth's history, oxygen rose to this level.

  20. On the kinetics of platinum silicide formation

    NASA Astrophysics Data System (ADS)

    Faber, Erik J.; Wolters, Rob A. M.; Schmitz, Jurriaan

    2011-02-01

    In this work, the kinetics of platinum silicide formation for thin Pt films (50 nm) on monocrystalline ⟨100⟩ silicon is investigated via in situ resistance measurements under isothermal (197-275 °C) conditions. For Pt2Si diffusion limited growth was observed. For PtSi formation, however, no linear relation between silicide thickness and √t was found. PtSi growth over time could be described using the Avrami relation rendering Avrami exponent n =1.4±0.1. Additionally, an effective activation energy EA=1.7±0.1 eV was derived using the Avrami k values. The findings are important for obtaining well defined silicide films and silicide-to-silicon contacts.

  1. Physical Character and Morphology of Platinum Nanocrystals on Strontium Titanate

    NASA Astrophysics Data System (ADS)

    Gild, Joshua; Pierce, Michael; Komanicky, Vladimir; Barbour, Andi; You, Hoydoo

    2015-03-01

    The physical characteristics of platinum nanocrystals on single crystal strontium titanate, SrTiO3 , can effect the chemical properties of this important model catalyst. The morphology, epitaxy, distribution, and size of the Pt nano-crystals can all be controlled through different growth and processing mechanisms. Nanometer scale platinum thin films are deposited on strontium titanate at ambient temperatures then annealed at range of temperatures and in various oxidizing environments. The process of how these conditions influence the formation of uniformly epitaxial platinum crystals on the sample surface has been investigated using basic materials characterization techniques. Single crystal x-ray diffraction is the primary tool for these experiments, coupled with atomic force microscopy for morphology and x-ray and electron spectroscopy to determine chemical bonding between the particles and gases introduced into the system. These substrate supported nanoparticle samples will then be utilized in experiments to test their catalytic activity compared to an amorphous platinum film.

  2. Defining Therapy for Recurrent Platinum-sensitive Ovarian Cancer

    Cancer.gov

    In this phase III clinical trial, women with platinum-sensitive, recurrent ovarian epithelial, fallopian tube, or primary peritoneal cancer will be randomly assigned to undergo secondary cytoreductive surgery, if they are candidates for such surgery, and

  3. MEIOTIC BEHAVIOR OF PLATINUM-INDUCED ANEUPLOIDS IN PEARL MILLET

    EPA Science Inventory

    Cytotoxicity, measured by seed germination and seedling survival, and the clastogenic potential of platinum diaminodinitrodichloride were evaluated in pear millet (Pennisetum americanum (k) Schum). The study was conducted under controlled climatic conditions. Presoaked seed of pe...

  4. Interfacial electronic effects control the reaction selectivity of platinum catalysts.

    PubMed

    Chen, Guangxu; Xu, Chaofa; Huang, Xiaoqing; Ye, Jinyu; Gu, Lin; Li, Gang; Tang, Zichao; Wu, Binghui; Yang, Huayan; Zhao, Zipeng; Zhou, Zhiyou; Fu, Gang; Zheng, Nanfeng

    2016-05-01

    Tuning the electronic structure of heterogeneous metal catalysts has emerged as an effective strategy to optimize their catalytic activities. By preparing ethylenediamine-coated ultrathin platinum nanowires as a model catalyst, here we demonstrate an interfacial electronic effect induced by simple organic modifications to control the selectivity of metal nanocatalysts during catalytic hydrogenation. This we apply to produce thermodynamically unfavourable but industrially important compounds, with ultrathin platinum nanowires exhibiting an unexpectedly high selectivity for the production of N-hydroxylanilines, through the partial hydrogenation of nitroaromatics. Mechanistic studies reveal that the electron donation from ethylenediamine makes the surface of platinum nanowires highly electron rich. During catalysis, such an interfacial electronic effect makes the catalytic surface favour the adsorption of electron-deficient reactants over electron-rich substrates (that is, N-hydroxylanilines), thus preventing full hydrogenation. More importantly, this interfacial electronic effect, achieved through simple organic modifications, may now be used for the optimization of commercial platinum catalysts. PMID:26808458

  5. Water dissociation on silica in the presence of atomic platinum

    NASA Astrophysics Data System (ADS)

    Klett, Joachim; Elger, Benjamin; Krähling, Stephan; Kaiser, Bernhard; Jaegermann, Wolfram; Schäfer, Rolf

    2016-07-01

    We have investigated the adsorption of water on well-defined silica and silica/Pt interfaces by synchrotron X-Ray Photoelectron Spectroscopy (SXPS). For that purpose silica surfaces grown on Si have been covered with atomic platinum in order to facilitate water dissociation. Water was adsorbed from the gas phase at cryogenic temperatures and its dissociation was observed on clean and platinum coated surfaces. After desorption the adsorbed hydroxides decompose on the blank surface, whereas the hydroxides remain stable if the surface was modified with platinum. The principal reversibility of the hydroxylation process implies the necessity of point defects in order to stabilize hydroxides on well-ordered silica surfaces. Deposited platinum atoms are able to stabilize hydroxides in their proximity and act as an acceptor state on the silica surface.

  6. Interfacial electronic effects control the reaction selectivity of platinum catalysts

    NASA Astrophysics Data System (ADS)

    Chen, Guangxu; Xu, Chaofa; Huang, Xiaoqing; Ye, Jinyu; Gu, Lin; Li, Gang; Tang, Zichao; Wu, Binghui; Yang, Huayan; Zhao, Zipeng; Zhou, Zhiyou; Fu, Gang; Zheng, Nanfeng

    2016-05-01

    Tuning the electronic structure of heterogeneous metal catalysts has emerged as an effective strategy to optimize their catalytic activities. By preparing ethylenediamine-coated ultrathin platinum nanowires as a model catalyst, here we demonstrate an interfacial electronic effect induced by simple organic modifications to control the selectivity of metal nanocatalysts during catalytic hydrogenation. This we apply to produce thermodynamically unfavourable but industrially important compounds, with ultrathin platinum nanowires exhibiting an unexpectedly high selectivity for the production of N-hydroxylanilines, through the partial hydrogenation of nitroaromatics. Mechanistic studies reveal that the electron donation from ethylenediamine makes the surface of platinum nanowires highly electron rich. During catalysis, such an interfacial electronic effect makes the catalytic surface favour the adsorption of electron-deficient reactants over electron-rich substrates (that is, N-hydroxylanilines), thus preventing full hydrogenation. More importantly, this interfacial electronic effect, achieved through simple organic modifications, may now be used for the optimization of commercial platinum catalysts.

  7. Platinum Publications, April 1–May 27, 2016 | Poster

    Cancer.gov

    Platinum Publications are selected from articles by NCI at Frederick scientists published in 42 prestigious science journals. This list represents articles published during the time period shown above, as generated from PubMed.

  8. Platinum nanostructures formed by femtosecond laser irradiation in water

    SciTech Connect

    Huo Haibin; Shen Mengyan

    2012-11-15

    Platinum nanostructures with various morphologies, such as spike-like, ripple-like and array-like structures, have been fabricated by 400 nm and 800 nm femtosecond laser irradiation in water. Different structures can be formed on the surfaces as a function of the laser wavelength, the fluence and scan methods. The reflectance measurements of these structures show much larger absorption on the irradiated surfaces than untreated platinum surfaces.

  9. Controlled synthesis of novel octapod platinum nanocrystals under microwave irradiation

    SciTech Connect

    Dai, Lei; Chi, Quan; Zhao, Yanxi; Liu, Hanfan; Zhou, Zhongqiang; Li, Jinlin; Huang, Tao

    2014-01-01

    Graphical abstract: Under microwave irradiation, novel octapod Pt nanocrystals were synthesized by reducing H{sub 2}PtCl{sub 6} in TEG with PVP as a stabilizer. The as-prepared Pt nanocrystals displayed a unique octapod nanostructure with five little mastoids in each concave center. The use of KI was crucial to the formation of novel Pt octapods. Novel Octapod Platinum Nanocrystals. - Highlights: • A novel octapod Pt nanocrystals different from the common octapod were obtained. • The use of KI was crucial to the formation of the novel Pt octapods. • Microwave was readily employed in controlled synthesis of the novel Pt octapods. - Abstract: Microwave was employed in the shape-controlled synthesis of Pt nanoparticles. Novel octapod Pt nanocrystals enclosed with (1 1 1) facets were readily synthesized with H{sub 2}PtCl{sub 6} as a precursor, tetraethylene glycol (TEG) as both a solvent and a reducing agent, polyvinylpyrrolidone (PVP) as a stabilizer in the presence of an appropriate amount of KI under microwave irradiation for 140 s. The as-prepared Pt nanocrystals displayed a unique octapod nanostructure with five little mastoids in each concave center and exhibited higher electrocatalytic activity than commercial Pt black in the electro-oxidations of methanol and formic acid. The results demonstrated that the use of KI was crucial to the formation of Pt octapods. KI determined the formation of the novel octapod Pt nanocrystals by tuning up the reduction kinetics and adsorbing on the surfaces of growing Pt nanoparticles. The optimum molar ratio of H{sub 2}PtCl{sub 6}/KI/PVP was 1/30/45.

  10. Identification of platinum and palladium particles emitted from vehicles and dispersed into the surface environment.

    PubMed

    Prichard, Hazel M; Fisher, Peter C

    2012-03-20

    Platinum, palladium, and rhodium are emitted from vehicle catalytic converters. Until now, the form of precious metal particles in road dust and urban waste has not been identified. This study has located, imaged, and analyzed these particles in road dust and gully waste. Two fragments of catalytic converter have been observed in road dust. They are 40-80 μm in size and covered in many minute particles (<0.3 μm) of either platinum with minor rhodium or palladium. One fragment identified in gully sediment is smaller, 25 μm in diameter, hosting only one attached particle of palladium with minor rhodium. As fragments are washed off roads they begin to disintegrate and the precious metals become detached. Also precious metal-bearing particles have been located in incinerated sewage ash including a 20 μm diameter cluster of <3 μm sized platinum particles that may be the remains of a catalytic converter fragment that has survived incineration. The form of these precious metal-bearing particles described here reveals that as they are dispersed from roads they are likely to be present predominantly as two particle sizes. Either they are attached to larger fragments of catalytic converter or they are released as individual detached tiny <0.3 μm to nanoparticle sizes. PMID:22313190

  11. Oral etoposide (VP16) in platinum-resistant epithelial ovarian cancer (EOC).

    PubMed

    Alici, Süleyman; Saip, Pinar; Eralp, Yeşim; Aydiner, Adnan; Topuz, Erkan

    2003-08-01

    This phase II study evaluates the efficacy and toxicity of a prolonged schedule second-line and third-line treatment of oral VP16 in patients with measurable advanced ovarian cancer resistant to, or relapsed following, platinum-based chemotherapy. Twenty-two eligible women with progressive or relapsed ovarian cancer resistant to platinum-based therapy were included in this study. All the patients had received more than one prior treatment, and had evidence of disease progression within 6 months of the previous chemotherapy. Eleven patients had received more than two different chemotherapy regimens. Fifteen patients had received consolidation therapy with intraperitoneal cisplatin after an initial treatment course with six cycles of a platinum-based combination regimen. All patients with measurable disease observed in abdominal computed tomography scans were given oral VP16 at a daily dose of 50 mg/m2 for 14 consecutive days with 4 weekly intervals. Among 22 assessable patients, there were one complete response (CR) and three partial responses (PR), so the objective response rate, which is the addition of CR and PR rates, was 18%. Seven patients (32%) had stable disease. Median duration of response and stable disease was 2.5 months (range: 1-10 months). Overall median survival was 11 months from study entry (range: 3-36 months). Toxicity for most patients was mild, but a few severe myelotoxicities occurred, and there were no treatment-related deaths. According to World Health Organization toxicity criteria grade III/IV thrombocytopenia was seen in 4 of 22 patients, grade III/IV neutropenia in 6 of 22 patients, and grade III anemia was observed in 3 of 22 patients. Nonhematologic toxicity was mild, and mucositis was the most frequently observed nonhematologic toxicity. Oral etoposide has considerable activity with a tolerable toxicity profile for the treatment of platinum-resistant epithelial ovarian cancer. PMID:12902885

  12. In vitro permeation of platinum and rhodium through Caucasian skin.

    PubMed

    Franken, A; Eloff, F C; Du Plessis, J; Badenhorst, C J; Jordaan, A; Du Plessis, J L

    2014-12-01

    During platinum group metals (PGMs) refining the possibility exists for dermal exposure to PGM salts. The dermal route has been questioned as an alternative route of exposure that could contribute to employee sensitisation, even though literature has been focused on respiratory exposure. This study aimed to investigate the in vitro permeation of platinum and rhodium through intact Caucasian skin. A donor solution of 0.3mg/ml of metal, K2PtCl4 and RhCl3 respectively, was applied to the vertical Franz diffusion cells with full thickness abdominal skin. The receptor solution was removed at various intervals during the 24h experiment, and analysed with high resolution ICP-MS. Skin was digested and analysed by ICP-OES. Results indicated cumulative permeation with prolonged exposure, with a significantly higher mass of platinum permeating after 24h when compared to rhodium. The mass of platinum retained inside the skin and the flux of platinum across the skin was significantly higher than that of rhodium. Permeated and skin retained platinum and rhodium may therefore contribute to sensitisation and indicates a health risk associated with dermal exposure in the workplace. PMID:25084315

  13. Platinum compounds in children with cancer: toxicity and clinical management.

    PubMed

    Ruggiero, Antonio; Trombatore, Giovanna; Triarico, Silvia; Arena, Roberta; Ferrara, Pietro; Scalzone, Maria; Pierri, Filomena; Riccardi, Riccardo

    2013-11-01

    Platinum compounds are widely used in the treatment of pediatric tumors such as neuroblastoma, germ-cell tumors, osteosarcoma, retinoblastoma, hepatoblastoma, brain tumors (low-grade gliomas and medulloblastoma/PNET), and relapsed and refractory lymphomas. The three major platinum compounds (cisplatin, carboplatin, and oxaliplatin) have a similar pharmacokinetics profile and mechanism of action, but the differences in their chemical structure are responsible for their different antitumor activity and toxicity. In this review, we have described the main characteristics of cisplatin, carboplatin, and oxaliplatin, focusing on their toxic effects and possible strategies to prevent them to improve the clinical outcomes in pediatric cancer patients. The underlying mechanism of each platinum-related toxicity is shown together with the clinical manifestations. Furthermore, possible preventive strategies are suggested to reduce the negative impact of platinum compounds on the quality of life of children with cancer. Cisplatin seems to be mostly ototoxic and nephrotoxic, carboplatin mainly produces myelosuppression, whereas oxaliplatin induces predominantly peripheral sensory neurotoxicity. In contrast, nausea and vomiting can be linked to all platinum compounds, although cisplatin exerts the strongest emetic effect. A correct knowledge of pharmacokinetics and toxicological profile of platinum compounds may aid physicians prevent their toxicity on auditory, nervous, renal, and bone marrow function, improving the quality of life of pediatric cancer patients. PMID:23962902

  14. Sunscreening Agents

    PubMed Central

    Martis, Jacintha; Shobha, V; Sham Shinde, Rutuja; Bangera, Sudhakar; Krishnankutty, Binny; Bellary, Shantala; Varughese, Sunoj; Rao, Prabhakar; Naveen Kumar, B.R.

    2013-01-01

    The increasing incidence of skin cancers and photodamaging effects caused by ultraviolet radiation has increased the use of sunscreening agents, which have shown beneficial effects in reducing the symptoms and reoccurrence of these problems. Many sunscreen compounds are in use, but their safety and efficacy are still in question. Efficacy is measured through indices, such as sun protection factor, persistent pigment darkening protection factor, and COLIPA guidelines. The United States Food and Drug Administration and European Union have incorporated changes in their guidelines to help consumers select products based on their sun protection factor and protection against ultraviolet radiation, whereas the Indian regulatory agency has not yet issued any special guidance on sunscreening agents, as they are classified under cosmetics. In this article, the authors discuss the pharmacological actions of sunscreening agents as well as the available formulations, their benefits, possible health hazards, safety, challenges, and proper application technique. New technologies and scope for the development of sunscreening agents are also discussed as well as the role of the physician in patient education about the use of these agents. PMID:23320122

  15. Aqueous synthesis of near-infrared highly fluorescent platinum nanoclusters.

    PubMed

    García Fernández, Jenifer; Trapiella-Alfonso, Laura; Costa-Fernández, José M; Pereiro, Rosario; Sanz-Medel, Alfredo

    2015-05-29

    A one-step synthesis of near infrared fluorescent platinum nanoclusters (PtNCs) in aqueous medium is described. The proposed optimized procedure for PtNC synthesis is rather simple, fast and it is based on the direct metal reduction with NaBH4. Bidentated thiol ligands (lipoic acid) were selected as nanoclusters stabilizers in water media. The structural characterization revealed attractive features of the PtNCs, including small size, high water solubility, near-infrared luminescence centered at 680 nm, long-term stability and the highest quantum yield in water reported so far (47%) for PtNCs. Moreover, their stability in different pH media and an ionic strength of 0.2 M NaCl was studied and no significant changes in fluorescence emission were detected. In brief, they offer a new type of fluorescent noble metal nanoprobe with a great potential to be applied in several fields, including biolabeling and imaging experiments. PMID:25944823

  16. A Single-Site Platinum CO Oxidation Catalyst in Zeolite KLTL: Microscopic and Spectroscopic Determination of the Locations of the Platinum Atoms

    SciTech Connect

    Kistler, Joseph D.; Chotigkrai, Nutchapon; Xu, Pinghong; Enderle, Bryan; Praserthdam, Piyasan; Chen, Cong-Yan; Browning, Nigel D.; Gates, Bruce C.

    2014-07-01

    A stable site-isolated mononuclear platinum catalyst with a well-defined structure is presented. Platinum complexes supported in zeolite KLTL were synthesized from [Pt(NH3)4](NO3)2, oxidized at 633 K, and used to catalyze CO oxidation. Finally, IR and X-ray absorption spectra and electron micrographs determine the structures and locations of the platinum complexes in the zeolite pores, demonstrate the platinum-support bonding, and show that the platinum remained site isolated after oxidation and catalysis.

  17. DNA binding and anticancer activity of novel cyclometalated platinum (II) complexes.

    PubMed

    Mohammadi, Roghayeh; Yousefi, Reza; Aseman, Marzieh Dadkhah; Nabavizadeh, S Masoud; Rashidi, Mehdi

    2015-01-01

    This study describes anticancer activity and DNA binding properties of two cyclometalated platinum (II) complexes with non-leaving lipophilic ligands; deprotonated 2-phenylpryidine (ppy): C1 and deprotonated benzo[h] quinolone (bhq): C2. Both complexes demonstrate significant anticancer activity and were capable to stimulate Caspase-III activity in Jurkat cancer cells. The results of Acridine orange/Ethidium bromide(AO/EtB), along with those of Caspase-III activity suggest that these complexes can induce apoptosis in the cancer cells. Moreover, C1 with flexible chemical structure indicates considerably higher anticancer activity than C2 which possesses a higher structural rigidity. Additionally, C2 represents a complex which is in part inducing cancer cell death due to the cell injury (necrosis). The absorption spectra of DNA demonstrate a hypochromic effect in the presence of increasing concentration of these complexes, reflecting DNA structural alteration after drug binding. Also, EtB competition assay and docking results revealed partial intercalation and DNA groove binding for the metal complexes. Overall, from the therapeutic point of view, ppy containing platinum complex (C1) is a favored anticancer agent, because it induces signaling cell death (apoptosis) in cancer cells, and lacks the necrotic effect. PMID:25482721

  18. Profile of vintafolide (EC145) and its use in the treatment of platinum-resistant ovarian cancer

    PubMed Central

    Luyckx, Mathieu; Votino, Raffaella; Squifflet, Jean-Luc; Baurain, Jean-François

    2014-01-01

    Vintafolide is a promising targeted agent for recurrent platinum-resistant ovarian cancer, first, thanks to its mechanism of action and the characteristics of FRα in ovarian cancer, and, second, because of the favorable results observed in the first clinical trials on platinum-resistant ovarian cancer. Phase III clinical trials are currently ongoing and are expected to confirm these results. PMID:24729732

  19. Multi-Agent Information Classification Using Dynamic Acquaintance Lists.

    ERIC Educational Resources Information Center

    Mukhopadhyay, Snehasis; Peng, Shengquan; Raje, Rajeev; Palakal, Mathew; Mostafa, Javed

    2003-01-01

    Discussion of automated information services focuses on information classification and collaborative agents, i.e. intelligent computer programs. Highlights include multi-agent systems; distributed artificial intelligence; thesauri; document representation and classification; agent modeling; acquaintances, or remote agents discovered through…

  20. Insights into the structure-activity relationships of chiral 1,2-diaminophenylalkane platinum(II) anticancer derivatives.

    PubMed

    Berger, Gilles; Fusaro, Luca; Luhmer, Michel; Czapla-Masztafiak, Joanna; Lipiec, Ewelina; Szlachetko, Jakub; Kayser, Yves; Fernandes, Daniel L A; Sá, Jacinto; Dufrasne, François; Bombard, Sophie

    2015-07-01

    The structure-activity relationships of chiral 1,2-diaminophenylalkane platinum(II) anticancer derivatives are studied, including interactions with telomeric- and genomic-like DNA sequences, the pKa of their diaqua species, structural properties obtained from DFT calculations and resonant X-ray emission spectroscopy. The binding modes of the compounds to telomeric sequences were elucidated, showing no major differences with conventional cis-platinum(II) complexes like cisplatin, supporting that the cis-square planar geometry governs the binding of small Pt(II) complexes to G4 structures. Double-stranded DNA platination kinetics and acid-base constants of the diaqua species of the compounds were measured and compared, highlighting a strong steric dependence of the DNA-binding kinetics, but independent to stereoisomerism. Structural features of the compounds are discussed on the basis of dispersion-corrected DFT, showing that the most active series presents conformers for which the platinum atom is well devoid of steric hindrance. If reactivity indices derived from conceptual DFT do not show evidences for different reactivity between the compounds, RXES experiments provide new insight into the availability of platinum orbitals for binding to nucleophiles. PMID:25982100

  1. Epigenetic inactivation of the putative DNA/RNA helicase SLFN11 in human cancer confers resistance to platinum drugs

    PubMed Central

    Nogales, Vanesa; Reinhold, William C.; Varma, Sudhir; Martinez-Cardus, Anna; Moutinho, Catia; Moran, Sebastian; Heyn, Holger; Sebio, Ana; Barnadas, Agusti; Pommier, Yves; Esteller, Manel

    2016-01-01

    Platinum-derived drugs such as cisplatin and carboplatin are among the most commonly used cancer chemotherapy drugs, but very few specific molecular and cellular markers predicting differential sensitivity to these agents in a given tumor type have been clearly identified. Epigenetic gene silencing is increasingly being recognized as a factor conferring distinct tumoral drug sensitivity, so we have used a comprehensive DNA methylation microarray platform to interrogate the widely characterized NCI60 panel of human cancer cell lines with respect to CpG methylation status and cisplatin/carboplatin sensitivity. Using this approach, we have found promoter CpG island hypermethylation-associated silencing of the putative DNA/RNA helicase Schlafen-11 (SLFN11) to be associated with increased resistance to platinum compounds. We have also experimentally validated these findings in vitro. In this setting, we also identified the BRCA1 interacting DHX9 RNA helicase (also known as RHA) as a protein partner for SLFN11, suggesting a mechanistic pathway for the observed chemoresistance effect. Most importantly, we have been able to extend these findings clinically, following the observation that those patients with ovarian and non-small cell lung cancer carrying SLFN11 hypermethylation had a poor response to both cisplatin and carboplatin treatments. Overall, these results identify SLFN11 epigenetic inactivation as a predictor of resistance to platinum drugs in human cancer. PMID:26625211

  2. Trabectedin as a new chemotherapy option in the treatment of relapsed platinum sensitive ovarian cancer.

    PubMed

    Monk, Bradley J; Dalton, Heather; Benjamin, Ivor; Tanović, Adnan

    2012-01-01

    Trabectedin (ET-743, Yondelis®) is a novel marine antineoplastic alkaloid with a unique mechanism of action. The active substance trabectedin, a tetrahydroisoquinoline alkaloid, is a natural product originally isolated from the Caribbean sea squirt, Ecteinascidia turbinata and is currently manufactured by total synthesis. Trabectedin is licensed by the Spanish pharmaceutical drug company, PharmaMar and co-developed by Johnson & Johnson Pharmaceutical Research and Development, L.L.C., pursuant to a licensing agreement with PharmaMar. Trabectedin is the first anticancer marine-derived drug to be approved by the European Union. In 2007, trabectedin obtained marketing authorization from the European Commission and in many other countries worldwide for the treatment of patients with advanced soft tissue sarcoma (STS) after failure of anthracyclines and ifosfamide, or for those patients who are unsuitable to receive these agents. Based on the recently reported results of a large phase III study (OVA-301) comparing pegylated liposomal doxorubicin (PLD) alone with a combination of PLD and trabectedin in patients with recurrent ovarian cancer, in 2009 the European Commission granted marketing authorization for trabectedin combined with PLD for the treatment of patients with relapsed platinum-sensitive ovarian cancer. The results from OVA-301 showed that the combination of trabectedin and PLD improves progression-free survival and overall response rate over PLD alone with acceptable tolerance in the second-line treatment of recurrent ovarian cancer. In addition, an enhanced activity of trabectedin combined with PLD was observed in platinum sensitive patients, especially in those with a platinum-free interval ranging from 6 to 12 months. Overall, trabectedin-induced toxicities are mainly hematological and hepatic, with grade 3/4 neutropenia and thrombocytopenia observed in approximately 50% and 13% of patients, respectively, and grade 3/4 elevation of liver aminotransferases

  3. Platinum Nanoparticles Strongly Bonded to Freestanding Graphene

    NASA Astrophysics Data System (ADS)

    Thibado, Paul; Schoelz, J. K.; Ghosh, P. K.; Thompson, J.; Dong, L.; Neek-Amal, M.; Peeters, F. M.

    2015-03-01

    Freestanding graphene membranes were successfully functionalized with platinum nanoparticles (Pt NPs). The membranes were imaged using high-resolution transmission electron microscopy, revealing a homogeneous distribution of uniformly sized, single-crystal Pt NPs that exhibit a preferred orientation and nearest-neighbor distance. The Pt NPs were also found to be partially elevated by the graphene substrate, as deduced from atomic-resolution scanning tunneling microscopy (STM) images. Furthermore, the electrostatic force between the STM tip and sample was utilized to estimate the binding energy of the Pt NPs to the suspended graphene. Local strain accumulation due to strong sp3 bond formation is thought to be the origin of the Pt NP self-organization. Such detailed insight into the atomic nature of this functionalized system was only possible through the cooperation of dual microscopic techniques combined with molecular dynamics simulations. The findings are expected to shape future approaches to develop high-performance electronics based on nanoparticle-functionalized graphene as well as fuel cells using Pt NP catalysts. Financial support provided by the Office of Naval Research under Grant No. N00014-10-1-0181 and the National Science Foundation under Grant No. DMR-0855358.

  4. Superlattices of platinum and palladium nanoparticles

    SciTech Connect

    MARTIN,JAMES E.; WILCOXON,JESS P.; ODINEK,JUDY G.; PROVENCIO,PAULA P.

    2000-04-06

    The authors have used a nonionic inverse micelle synthesis technique to form nanoclusters of platinum and palladium. These nanoclusters can be rendered hydrophobic or hydrophilic by the appropriate choice of capping ligand. Unlike Au nanoclusters, Pt nanoclusters show great stability with thiol ligands in aqueous media. Alkane thiols, with alkane chains ranging from C{sub 6} to C{sub 18} were used as hydrophobic ligands, and with some of these they were able to form 2-D and/or 3-D superlattices of Pt nanoclusters as small as 2.7 nm in diameter. Image processing techniques were developed to reliably extract from transmission electron micrographs (TEMs) the particle size distribution, and information about the superlattice domains and their boundaries. The latter permits one to compute the intradomain vector pair correlation function of the particle centers, from which they can accurately determine the lattice spacing and the coherent domain size. From these data the gap between the particles in the coherent domains can be determined as a function of the thiol chain length. It is found that as the thiol chain length increases, the gaps between particles within superlattice domains increases, but more slowly than one might expect, possibly indicating thiol chain interdigitation.

  5. Platinum Attachments on Iron Oxide Nanoparticle Surfaces

    SciTech Connect

    Palchoudhury, Soubantika; Xu, Yaolin; An, Wei; Turner, C. H.; Bao, Yuping

    2010-04-30

    Platinum nanoparticles supported on metal oxide surfaces have shown great potential as heterogeneous catalysts to accelerate electrochemical processes, such as the oxygen reduction reaction in fuel cells. Recently, the use of magnetic supports has become a promising research topic for easy separation and recovery of catalysts using magnets, such as Pt nanoparticles supported on iron oxide nanoparticles. The attachment of Pt on iron oxide nanoparticles is limited by the wetting ability of the Pt (metal) on ceramic surfaces. A study of Pt nanoparticle attachment on iron oxide nanoparticle surfaces in an organic solvent is reported, which addresses the factors that promote or inhibit such attachment. It was discovered that the Pt attachment strongly depends on the capping molecules of the iron oxide seeds and the reaction temperature. For example, the attachment of Pt nanoparticles on oleic acid coated iron oxide nanoparticles was very challenging, because of the strong binding between the carboxylic groups and iron oxide surfaces. In contrast, when nanoparticles are coated with oleic acid/tri-n-octylphosphine oxide or oleic acid/oleylamine, a significant increase in Pt attachment was observed. Electronic structure calculations were then applied to estimate the binding energies between the capping molecules and iron ions, and the modeling results strongly support the experimental observations.

  6. Platinum and Gold Complexes for OLEDs.

    PubMed

    Tang, Man-Chung; Chan, Alan Kwun-Wa; Chan, Mei-Yee; Yam, Vivian Wing-Wah

    2016-08-01

    Encouraging efforts on the design of high-performance organic materials and smart architecture during the past two decades have made organic light-emitting device (OLED) technology an important competitor for the existing liquid crystal displays. Particularly, the development of phosphorescent materials based on transition metals plays a crucial role for this success. Apart from the extensively studied iridium(III) complexes with d(6) electronic configuration and octahedral geometry, the coordination-unsaturated nature of d(8) transition metal complexes with square-planar structures has been found to provide intriguing spectroscopic and luminescence properties. This article briefly summarizes the development of d(8) platinum(II) and gold(III) complexes and their application studies in the fabrication of phosphorescent OLEDs. An in-depth understanding of the nature of the excited states has offered a great opportunity to fine-tune the emission colors covering the entire visible spectrum as well as to improve their photophysical properties. With good device engineering, high performance vacuum-deposited OLEDs with external quantum efficiencies (EQEs) of up to 30 % and solution-processable OLEDs with EQEs of up to 10 % have been realized by modifying the cyclometalated or pincer ligands of these metal complexes. These impressive demonstrations reveal that d(8) metal complexes are promising candidates as phosphorescent materials for OLED applications in displays as well as in solid-state lighting in the future. PMID:27573398

  7. Platinum metals in magmatic sulfide ores

    USGS Publications Warehouse

    Naldrett, A.J.; Duke, J.M.

    1980-01-01

    Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example. Copyright ?? 1980 AAAS.

  8. In vitro antimicrobial activity of peroxide-based bleaching agents.

    PubMed

    Napimoga, Marcelo Henrique; de Oliveira, Rogério; Reis, André Figueiredo; Gonçalves, Reginaldo Bruno; Giannini, Marcelo

    2007-06-01

    Antibacterial activity of 4 commercial bleaching agents (Day White, Colgate Platinum, Whiteness 10% and 16%) on 6 oral pathogens (Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis, Candida albicans, Lactobacillus casei, and Lactobacillus acidophilus) and Staphylococcus aureus were evaluated. A chlorhexidine solution was used as a positive control, while distilled water was the negative control. Bleaching agents and control materials were inserted in sterilized stainless-steel cylinders that were positioned under inoculated agar plate (n = 4). After incubation according to the appropriate period of time for each microorganism, the inhibition zones were measured. Data were analyzed by 2-way analysis of variance and Tukey test (a = 0.05). All bleaching agents and the chlorhexidine solution produced antibacterial inhibition zones. Antimicrobial activity was dependent on peroxide-based bleaching agents. For most microorganisms evaluated, bleaching agents produced inhibition zones similar to or larger than that observed for chlorhexidine. C albicans, L casei, and L acidophilus were the most resistant microorganisms. PMID:17625621

  9. Tuning selectivity of electrochemical reactions by atomically dispersed platinum catalyst

    NASA Astrophysics Data System (ADS)

    Choi, Chang Hyuck; Kim, Minho; Kwon, Han Chang; Cho, Sung June; Yun, Seongho; Kim, Hee-Tak; Mayrhofer, Karl J. J.; Kim, Hyungjun; Choi, Minkee

    2016-03-01

    Maximum atom efficiency as well as distinct chemoselectivity is expected for electrocatalysis on atomically dispersed (or single site) metal centres, but its realization remains challenging so far, because carbon, as the most widely used electrocatalyst support, cannot effectively stabilize them. Here we report that a sulfur-doped zeolite-templated carbon, simultaneously exhibiting large sulfur content (17 wt% S), as well as a unique carbon structure (that is, highly curved three-dimensional networks of graphene nanoribbons), can stabilize a relatively high loading of platinum (5 wt%) in the form of highly dispersed species including site isolated atoms. In the oxygen reduction reaction, this catalyst does not follow a conventional four-electron pathway producing H2O, but selectively produces H2O2 even over extended times without significant degradation of the activity. Thus, this approach constitutes a potentially promising route for producing important fine chemical H2O2, and also offers opportunities for tuning the selectivity of other electrochemical reactions on various metal catalysts.

  10. Dynamics of Single Hydrogen Bubbles at a Platinum Microelectrode.

    PubMed

    Yang, Xuegeng; Karnbach, Franziska; Uhlemann, Margitta; Odenbach, Stefan; Eckert, Kerstin

    2015-07-28

    Bubble dynamics, including the formation, growth, and detachment, of single H2 bubbles was studied at a platinum microelectrode during the electrolysis of 1 M H2SO4 electrolyte. The bubbles were visualized through a microscope by a high-speed camera. Electrochemical measurements were conducted in parallel to measure the transient current. The periodic current oscillations, resulting from the periodic formation and detachment of single bubbles, allow the bubble lifetime and size to be predicted from the transient current. A comparison of the bubble volume calculated from the current and from the recorded bubble image shows a gas evolution efficiency increasing continuously with the growth of the bubble until it reaches 100%. Two different substrates, glass and epoxy, were used to embed the Pt wire. While nearly no difference was found with respect to the growth law for the bubble radius, the contact angle differs strongly for the two types of cell. Data provided for the contact point evolution further complete the image of single hydrogen bubble growth. Finally, the velocity field driven by the detached bubble was measured by means of PIV, and the effects of the convection on the subsequent bubble were evaluated. PMID:26133052

  11. Tuning selectivity of electrochemical reactions by atomically dispersed platinum catalyst

    PubMed Central

    Choi, Chang Hyuck; Kim, Minho; Kwon, Han Chang; Cho, Sung June; Yun, Seongho; Kim, Hee-Tak; Mayrhofer, Karl J. J.; Kim, Hyungjun; Choi, Minkee

    2016-01-01

    Maximum atom efficiency as well as distinct chemoselectivity is expected for electrocatalysis on atomically dispersed (or single site) metal centres, but its realization remains challenging so far, because carbon, as the most widely used electrocatalyst support, cannot effectively stabilize them. Here we report that a sulfur-doped zeolite-templated carbon, simultaneously exhibiting large sulfur content (17 wt% S), as well as a unique carbon structure (that is, highly curved three-dimensional networks of graphene nanoribbons), can stabilize a relatively high loading of platinum (5 wt%) in the form of highly dispersed species including site isolated atoms. In the oxygen reduction reaction, this catalyst does not follow a conventional four-electron pathway producing H2O, but selectively produces H2O2 even over extended times without significant degradation of the activity. Thus, this approach constitutes a potentially promising route for producing important fine chemical H2O2, and also offers opportunities for tuning the selectivity of other electrochemical reactions on various metal catalysts. PMID:26952517

  12. Kinetics of Platinum-Catalyzed Decomposition of Hydrogen Peroxide

    NASA Astrophysics Data System (ADS)

    Vetter, Tiffany A.; Colombo, D. Philip, Jr.

    2003-07-01

    CIBA Vision Corporation markets a contact lens cleaning system that consists of an AOSEPT disinfectant solution and an AOSEPT lens cup. The disinfectant is a buffered 3.0% m/v hydrogen peroxide solution and the cup includes a platinum-coated AOSEPT disc. The hydrogen peroxide disinfects by killing bacteria, fungi, and viruses found on the contact lenses. Because the concentration of hydrogen peroxide needed to disinfect is irritating to eyes, the hydrogen peroxide needs to be neutralized, or decomposed, before the contact lenses can be used again. A general chemistry experiment is described where the kinetics of the catalyzed decomposition of the hydrogen peroxide are studied by measuring the amount of oxygen generated as a function of time. The order of the reaction with respect to the hydrogen peroxide, the rate constant, and the energy of activation are determined. The integrated rate law is used to determine the time required to decompose the hydrogen peroxide to a concentration that is safe for eyes.

  13. Catalytic ignition of fuel/oxygen/nitrogen mixtures over platinum

    SciTech Connect

    Cho, P.; Law, C.K.

    1986-11-01

    Ignition of fuel/oxygen/nitrogen mixtures over platinum wire is experimentally studied by using microcalorimetry and by restricting the flow to the low Reynolds number range so that axisymmetry prevails. The fuels studied are propane, butane, propylene, ethylene, carbon monoxide, and hydrogen. Parameters investigated include flow velocity, fuel type and concentration, and oxygen concentration. The catalytic ignition temperatures of the various fuels are accurately determined over extensive ranges of fuel/oxygen/nitrogen concentrations. Results show two distinctly opposite ignition trends depending on the nature of the fuel. That is, the ignition temperature of lean propane/air and butane/air mixtures decreases as their fuel concentration is increased, while the reverse trend is observed for lean mixtures of propylene, ethylene, carbon monoxide, and hydrogen with air. Furthermore, the ignition of propane depends primarily on fuel concentration, while the ignition of carbon monoxide depends on fuel and oxygen concentrations to a comparable extent. These results are explained on the basis of hierarchical surface adsorption strengths of the different reactants in effecting catalytic ignition. Additional phenomena of interest are observed and discussed.

  14. Eribulin mesylate (halichondrin B Analog E7389) in platinum-resistant and platinum-sensitive ovarian cancer: a two-cohort, phase II study

    PubMed Central

    Hensley, Martee L.; Kravetz, Sara; Jia, Xiaoyu; Iasonos, Alexia; Tew, William; Pereira, Lauren; Sabbatini, Paul; Whalen, Christin; Aghajanian, Carol A.; Zarwan, Corinne; Berlin, Suzanne

    2011-01-01

    Background Eribulin mesylate is a tubulin inhibitor with activity superior to paclitaxel in NIH:OVCAR-3 human epithelial ovarian cancer xenograft models. We sought to assess the efficacy of eribulin in platinum-resistant and platinum-sensitive recurrent ovarian cancer. Methods Patients with recurrent measurable epithelial ovarian cancer, ≤2 prior cytotoxic regimens, and adequate organ function were enrolled into two separate cohorts: 1) Platinum resistant (progression-free interval from last platinum-based therapy <6 months); and 2) Platinum sensitive (progression-free interval from last platinum-based therapy ≥6 months). Treatment: Eribulin 1.4 mg/m2 over 15 minutes by vein on days 1 and 8, every 21 days. Efficacy was determined by objective response by computed tomography. Results Platinum-resistant cohort: Thirty-seven patients enrolled. Thirty-six patients were evaluable for response and toxicity. Two patients achieved partial response (PR, 5.5%). Sixteen (44%) had a best response of stable disease. Median progression-free survival was 1.8 months (95% confidence interval, 1.4–2.8 months). Platinum-sensitive cohort: Thirty-seven patients enrolled, and all were evaluable for response. Seven patients achieved partial response (PR, 19%). Median progression-free survival was 4.1 months (95% confidence interval, 2.8–5.8 months). The major toxicity was grade 3 or 4 neutropenia (42% in platinum-resistant patients; 54% in platinum-sensitive patients). Conclusions Eribulin achieved objective response in 5.5% of women with platinum-resistant recurrent ovarian cancer and in 19% of women with platinum-sensitive disease. Median progression-free survival was 1.8 months in the platinum-resistant group and 4.1 months in the platinum-sensitive group. PMID:21935916

  15. Vibrational Recognition of Adsorption Sites for CO on Platinum and Platinum-Ruthenium Surfaces.

    SciTech Connect

    Dabo, Ismaila; Wieckowski, Andrzei; Marzari, Nicola N.

    2007-09-01

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. We have studied the vibrational properties of CO adsorbed on platinum and platinum-ruthenium surfaces using density-functional perturbation theory within the Perdew-Burke-Ernzerhof generalizedgradient approximation. The calculated C-O stretching frequencies are found to be in excellent agreement with spectroscopic measurements. The frequency shifts that take place when the surface is covered with ruthenium monolayers are also correctly predicted. This agreement for both shifts and absolute vibrational frequencies is made more remarkable by the frequent failure of local and semilocal exchange-correlation functionals in predicting the stability of the different adsorption sites for CO on transition metal surfaces. We have investigated the chemical origin of the C-O frequency shifts introducing an orbital-resolved analysis of the force and frequency density of states, and assessed the effect of donation and backdonation on the CO vibrational frequency using a GGA + molecular U approach. These findings rationalize and establish the accuracy of density-functional calculations in predicting absolute vibrational frequencies, notwithstanding the failure in determining relative adsorption energies, in the strong chemisorption regime.

  16. Characterization of Platinum and Iridium Oxyhydrate Surface Layers from Platinum and Iridium Foils.

    PubMed

    Johnson, Benjamin; Ranjan, Chinmoy; Greiner, Mark; Arrigo, Rosa; Schuster, Manfred Erwin; Höpfner, Britta; Gorgoi, Mihaela; Lauermann, Iver; Willinger, Marc; Knop-Gericke, Axel; Schlögl, Robert

    2016-07-01

    Platinum and iridium polycrystalline foils were oxidized electrochemically through anodization to create thin platinum and iridium hydrous oxide layers, which were analyzed through laboratory photoelectron spectroscopy during heating and time series (temperature-programmed spectroscopy). The films contain oxygen in the form of bound oxides, water, and hydroxides and were investigated by depth profiling with high-energy photoelectron spectroscopy. The Pt films are unstable and begin to degrade immediately after removal from the electrolyte to form core-shell structures with a metallic inner core and a hydrous oxide outer shell almost devoid of Pt. However, evidence was found for metastable intermediate states of degradation; therefore, it may be possible to manufacture PtOx phases with increased stability. Heating the film to even 100 °C causes accelerated degradation, which shows that stoichiometric oxides such as PtO2 or PtO are not the active species in the electrolyte. The Ir films exhibit increased stability and higher surface Ir content, and gentle heating at low temperatures leads to a decrease in defect density. Although both layers are based on noble metals, their surface structures are markedly different. The complexity of such hydrous oxide systems is discussed in detail with the goal of identifying the film composition more precisely. PMID:27226255

  17. BOWIEITE: A NEW RHODIUM-IRIDIUM-PLATINUM SULFIDE IN PLATINUM-ALLOY NUGGETS, GOODNEWS BAY, ALASKA.

    USGS Publications Warehouse

    Desborough, George A.; Criddle, Alan J.

    1984-01-01

    Bowieite (Rh,Ir,Pt)//2S//3, a new mineral species, is found in three nuggets of platinum from Goodnews Bay, Alaska. In linearly polarized reflected light, and compared to the host, higher reflecting white platinum-iridium alloy, bowieite is pale gray to pale gray-brown; neither bireflectance nor reflectance pleochroism is apparent. With polars crossed, its anisotropic rotation tints vary from gray to dark brown. Luminance values (relative to the CIE illuminant C) for R//1 and R//2, computed from full spectral data for the most bireflectant grain, are 45. 8% and 48. 2% in air, and 30. 5% and 33. 0% in oil, respectively. VHN//1//0//0 1288 (858 to 1635). Bowieite is orthorhombic, space group Pnca, with a 8. 454(7) -8. 473(8), b 5. 995(1)-6. 002(7), c 6. 143(1)-6. 121(8) A, Z equals 4. Some grains that are 2. 6 to 3. 8 atomic % metal-deficient occur as an optically coherent rim on bowieite; the rim and the bowieite grain are not optically continuous.

  18. Evolution of platinum concentration in soil and sediment from urban environment

    NASA Astrophysics Data System (ADS)

    Jean-Soro, L.

    2012-04-01

    the study was carried out to determine the association of platinum with the soil and sediment constituting phases using solid micro-analyses techniques, including X-ray fluorescence microscopy and transmission electron microscopy. These results show that the composition of soil has an influence on the sorption and the mobilization of Pt.

  19. Platinum in the environment: frequency of reactions to platinum-group elements in patients with dermatitis and urticaria.

    PubMed

    Santucci, B; Valenzano, C; de Rocco, M; Cristaudo, A

    2000-12-01

    The aim of the present paper is to evaluate whether increasing environmental exposure increases the frequency of the positive prick and patch test reactions to certain chlorinated platinum salts in patients with dermatitis and urticaria. 800 consecutive subjects with contact dermatitis (n=749) and urticaria (n=51) were variously patch and prick tested with 30 haptens of a standard series, with aqueous solutions of, respectively, hexachloroplatinic acid (H2[PtCl6]), potassium tetrachloroplatinate (K2[PtCl4]), sodium hexachloroplatinate (Na2[PtCl6]), iridium chloride (IrCl3), rhodium chloride (RhCl3) and palladium chloride (PdCl2), and with 16 common inhalants. 153 workers, variably exposed in a platinum refinery, were patch and prick tested only with solutions containing platinum-group elements at various concentrations and with 16 common inhalants. Platinum-group elements did not elicit positive patch or prick test reactions in non-occupationally exposed subjects. In contrast, in exposed workers, positive patch test reactions at day 2 and at 25 min, respectively, were found in 2 subjects with hand dermatitis and in 2 with urticaria and asthma. 22 out of the 153 workers, 18 of whom had rhinitis, asthma, and urticaria, gave positive prick test reactions to 1 or more salts. Furthermore, on patch and prick testing, 4 cross-reactions between platinum, palladium, iridium and rhodium were demonstrated. In conclusion, the test results demonstrate that the present concentration in the environment does not increase the incidence of reactions to platinum salts in patients with dermatitis and/or urticaria. However, if the average level of environmental platinum exposure approaches those existing in industrial settings in the future, we are going to observe more frequent health effects. PMID:11140383

  20. 34 CFR 303.15 - Include; including.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Include; including. 303.15 Section 303.15 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION EARLY INTERVENTION PROGRAM FOR INFANTS AND TODDLERS...

  1. Structures of 38-atom gold-platinum nanoalloy clusters

    SciTech Connect

    Ong, Yee Pin; Yoon, Tiem Leong; Lim, Thong Leng

    2015-04-24

    Bimetallic nanoclusters, such as gold-platinum nanoclusters, are nanomaterials promising wide range of applications. We perform a numerical study of 38-atom gold-platinum nanoalloy clusters, Au{sub n}Pt{sub 38−n} (0 ≤ n ≤ 38), to elucidate the geometrical structures of these clusters. The lowest-energy structures of these bimetallic nanoclusters at the semi-empirical level are obtained via a global-minimum search algorithm known as parallel tempering multi-canonical basin hopping plus genetic algorithm (PTMBHGA), in which empirical Gupta many-body potential is used to describe the inter-atomic interactions among the constituent atoms. The structures of gold-platinum nanoalloy clusters are predicted to be core-shell segregated nanoclusters. Gold atoms are observed to preferentially occupy the surface of the clusters, while platinum atoms tend to occupy the core due to the slightly smaller atomic radius of platinum as compared to gold’s. The evolution of the geometrical structure of 38-atom Au-Pt clusters displays striking similarity with that of 38-atom Au-Cu nanoalloy clusters as reported in the literature.

  2. Oxidation Reaction Induced Structural Changes in Sub-Nanometer Platinum Supported on Alumina

    DOE PAGESBeta

    DeBusk, Melanie Moses; Allard, Jr, Lawrence Frederick; Blom, Douglas Allen; Narula, Chaitanya Kumar

    2015-01-01

    Platinum supported on alumina is an essential component of emission treatment catalysts used in transportation. Theoretical, experimental, and mechanistic aspects of platinum particles supported on a variety of supports have been extensively studied; however, available experimental information on the behavior of single vs. sub-nanometer platinum is extremely limited. To bridge the knowledge gap between single supported platinum and well-formed supported platinum nanoparticles, we have carried out synthesis, characterization, and CO and NO oxidation studies of sub-nanometer platinum supported on α, θ, and γ-Al2O3 and monitored changes in structure upon exposure to CO and NO oxidation conditions. We find that sub-nanometermore » Pt is highly effective for CO oxidation due to high platinum dispersion but is not very efficient as NO oxidation catalyst. Furthermore, sub-nanometer platinum agglomerates rapidly under CO or NO oxidation conditions to form nanoparticles.« less

  3. Oxidation-induced structural changes in sub-nanometer platinum supported on alumina

    SciTech Connect

    DeBusk, Melanie Moses; Allard, Jr, Lawrence Frederick; Blom, Douglas Allen; Narula, Chaitanya Kumar

    2015-06-26

    Platinum supported on alumina is an essential component of emission treatment catalysts used in transportation. Theoretical, experimental, and mechanistic aspects of platinum particles supported on a variety of supports have been extensively studied; however, available experimental information on the behavior of single vs. sub-nanometer platinum is extremely limited. To bridge the knowledge gap between single supported platinum and well-formed supported platinum nanoparticles, we have carried out synthesis, characterization, and CO and NO oxidation studies of sub-nanometer platinum supported on α, θ, and γ-Al2O3 and monitored changes in structure upon exposure to CO and NO oxidation conditions. Furthermore, we find that sub-nanometer Pt is highly effective for CO oxidation due to high platinum dispersion but is not very efficient as NO oxidation catalyst. Lastly, sub-nanometer platinum agglomerates rapidly under CO or NO oxidation conditions to form nanoparticles.

  4. Oxidation-induced structural changes in sub-nanometer platinum supported on alumina

    DOE PAGESBeta

    DeBusk, Melanie Moses; Allard, Jr, Lawrence Frederick; Blom, Douglas Allen; Narula, Chaitanya Kumar

    2015-06-26

    Platinum supported on alumina is an essential component of emission treatment catalysts used in transportation. Theoretical, experimental, and mechanistic aspects of platinum particles supported on a variety of supports have been extensively studied; however, available experimental information on the behavior of single vs. sub-nanometer platinum is extremely limited. To bridge the knowledge gap between single supported platinum and well-formed supported platinum nanoparticles, we have carried out synthesis, characterization, and CO and NO oxidation studies of sub-nanometer platinum supported on α, θ, and γ-Al2O3 and monitored changes in structure upon exposure to CO and NO oxidation conditions. Furthermore, we find thatmore » sub-nanometer Pt is highly effective for CO oxidation due to high platinum dispersion but is not very efficient as NO oxidation catalyst. Lastly, sub-nanometer platinum agglomerates rapidly under CO or NO oxidation conditions to form nanoparticles.« less

  5. Platinum nanoparticles on electrospun titania nanofibers as hydrogen sensing materials working at room temperature.

    PubMed

    Fratoddi, Ilaria; Macagnano, Antonella; Battocchio, Chiara; Zampetti, Emiliano; Venditti, Iole; Russo, Maria V; Bearzotti, Andrea

    2014-08-01

    Platinum nanoparticles (PtNPs), with diameters of 3-10 nm, were synthesized by water phase reduction, using 3-mercapto-1-propanesulfonate (3MPS) as a hydrophilic capping agent. PtNPs were deposited by a dipcoating technique on titania nanofibers (TiO2NFs), obtained by electrospinning. The investigated properties of the Pt-TiO2 hybrid at room temperature show that this material combines the properties of photoconduction of titania and the photocatalytic activity of the hybrid. To assess the best performance of Pt-TiO2, different measurements were performed at room temperature, comparing hydrogen response under UV of the uncoated TiO2NFs, compared with the Pt-TiO2 system prepared with two different amounts of PtNPs. During the sensing tests toward hydrogen an enhancement of photoconductivity (150%), an increase in response (400%) and an overall improvement of their dynamic behaviour were observed. PMID:24981799

  6. Toward overcoming cisplatin resistance via sterically hindered platinum(II) complexes.

    PubMed

    Yu, Haiyan; Gou, Shaohua; Wang, Zhimei; Chen, Feihong; Fang, Lei

    2016-05-23

    A number of platinum(II) complexes with steric hindrance derived from (1R,2R)-N(1)-benzylcyclohexane-1,2-diamine derivatives were designed and prepared. Biological assay indicated that most complexes showed antitumor activity against the tested cancer cell lines, especially those with chloride anions as leaving groups had compatible or superior activity to cisplatin and oxaliplatin. Complex 2a, as the most potent agent, is also sensitive to cisplatin resistant SGC7901/CDDP cancer cell line, which has been subsequently studied by cellular uptake, flow cytometry, gel electrophoresis and western blot assays. The steric hindrance resulting from a pending 2-fluorobenzyl moiety of the ligand might be the key factor for its ability to overcome cisplatin resistant cancer cells. PMID:26974381

  7. Dimethylformamide-mediated synthesis of water-soluble platinum nanodendrites for ethanol oxidation electrocatalysis.

    PubMed

    Mourdikoudis, Stefanos; Chirea, Mariana; Altantzis, Thomas; Pastoriza-Santos, Isabel; Pérez-Juste, Jorge; Silva, Fernando; Bals, Sara; Liz-Marzán, Luis M

    2013-06-01

    Herein we describe the synthesis of water-soluble platinum nanodendrites in dimethylformamide (DMF), in the presence of polyethyleneimine (PEI) as a stabilizing agent. The average size of the dendrites is in the range of 20-25 nm while their porosity can be tuned by modifying the concentration of the metal precursor. Electron tomography revealed different crystalline orientations of nanocrystallites in the nanodendrites and allowed a better understanding of their peculiar branching and porosity. The high surface area of the dendrites (up to 22 m(2) g(-1)) was confirmed by BET measurements, while X-ray diffraction confirmed the abundance of high-index facets in the face-centered-cubic crystal structure of Pt. The prepared nanodendrites exhibit excellent performance in the electrocatalytic oxidation of ethanol in alkaline solution. Sensing, selectivity, cycleability and great tolerance toward poisoning were demonstrated by cyclic voltammetry measurements. PMID:23613112

  8. BRCA1 epigenetic inactivation predicts sensitivity to platinum-based chemotherapy in breast and ovarian cancer

    PubMed Central

    Stefansson, Olafur A.; Villanueva, Alberto; Vidal, August; Martí, Lola; Esteller, Manel

    2012-01-01

    Germline mutations in the BRCA1 or BRCA2 genes are associated with an increased risk of breast and ovarian cancer development. Both genes are involved in DNA repair, and tumors harboring genetic defects in them are thought to be more sensitive to DNA-damaging agents used in chemotherapy. However, as only a minority of breast and ovarian cancer patients carry BRCA1 or BRCA2 mutations, few patients are likely to benefit from these pharmacogenetic biomarkers. Herein, we show that, in cancer cell lines and xenografted tumors, BRCA1 CpG island promoter hypermethylation-associated silencing also predicts enhanced sensitivity to platinum-derived drugs to the same extent as BRCA1 mutations. Most importantly, BRCA1 hypermethylation proves to be a predictor of longer time to relapse and improved overall survival in ovarian cancer patients undergoing chemotherapy with cisplatin. PMID:23069641

  9. Carboxyl-cored dendrimer and toluene-assisted fabrication of uniform platinum nanodendrites at a water/oil interface and their potential application as a catalyst

    NASA Astrophysics Data System (ADS)

    Gao, Shuyan; Zhang, Hongjie; Liu, Xudong; Wang, Xiaomei; Sun, Dehui; Peng, Chunyun; Zheng, Guoli

    2006-03-01

    Uniform platinum nanodendrites have been prepared at a water/oil interface by a facile catalyst-free method at room temperature. This is carried out by introducing NaBH4 into the platinum precursor solution in the presence of the second generation of carboxyl-cored dendrimer ([G-2]-CO2H dendrimer) and toluene to act as a protective agent and a linker, respectively. The average fractal dimension of 1.61 of the obtained platinum nanodendrites is calculated by analysing the transmission electron micrographs using the programs Fractal Dimension Version 1.1 and Fractal Dimension Calculator. Control experiments show that the fabrication of platinum nanodendrites can be operated with a wide parameter window, which undoubtedly raises the degree of control of the synthesis process. The potential application of such a nanostructure as a catalyst is investigated, and the results reveal that they show highly efficient catalytic properties for the typical redox reaction between hexacyanoferrate (III) and thiosulfate ions at 301 K.

  10. High ERCC1 expression is associated with platinum-resistance, but not survival in patients with epithelial ovarian cancer

    PubMed Central

    Du, Pei; Wang, Yifeng; Chen, Liquan; Gan, Yaping; Wu, Qinian

    2016-01-01

    The present study aimed to investigate the association between excision repair cross-complementation group 1 (ERCC1) expression and clinical resistance to platinum-based chemotherapy or clinical characteristics, including survival time, in patients with epithelial ovarian cancer (EOC). ERCC1 expression was determined by immunohistochemical staining in 92 tumor specimens from patients with EOC. The effect of ERCC1 expression on progression-free survival time (PFS) or overall survival time (OS), and its association with clinical resistance to platinum-based chemotherapy was investigated by Kaplan-Meier survival analysis, Cox regression analysis and the χ2 test. Of 92 patients with EOC, 89.13% (82/92) had ERCC1-positive tumors. The positive rate was significantly higher in platinum-resistant patients compared with those who were platinum-responding (P<0.05). The PFS and median OS were 12 and 30 months, respectively, in ERCC1 high expression patients, and 17 and 39 months, respectively, in ERCC1 low expression patients. However, there was no statistically significant difference in PFS (P=0.099) or OS (P=0.103) between the high and low expression groups. Furthermore, it was identified that ERCC1 was not an independent factor affecting the prognosis of patients with EOC based on Cox proportional hazards regression analysis. These results demonstrate that high ERCC1 expression is associated with resistance to platinum-based chemotherapy, but not with survival time, and ERCC1 protein expression is not an independent factor or the only factor affecting the prognosis of patients with EOC. PMID:27446360

  11. Platinum nanoparticles on electrospun titania nanofibers as hydrogen sensing materials working at room temperature

    NASA Astrophysics Data System (ADS)

    Fratoddi, Ilaria; Macagnano, Antonella; Battocchio, Chiara; Zampetti, Emiliano; Venditti, Iole; Russo, Maria V.; Bearzotti, Andrea

    2014-07-01

    Platinum nanoparticles (PtNPs), with diameters of 3-10 nm, were synthesized by water phase reduction, using 3-mercapto-1-propanesulfonate (3MPS) as a hydrophilic capping agent. PtNPs were deposited by a dipcoating technique on titania nanofibers (TiO2NFs), obtained by electrospinning. The investigated properties of the Pt-TiO2 hybrid at room temperature show that this material combines the properties of photoconduction of titania and the photocatalytic activity of the hybrid. To assess the best performance of Pt-TiO2, different measurements were performed at room temperature, comparing hydrogen response under UV of the uncoated TiO2NFs, compared with the Pt-TiO2 system prepared with two different amounts of PtNPs. During the sensing tests toward hydrogen an enhancement of photoconductivity (150%), an increase in response (400%) and an overall improvement of their dynamic behaviour were observed.Platinum nanoparticles (PtNPs), with diameters of 3-10 nm, were synthesized by water phase reduction, using 3-mercapto-1-propanesulfonate (3MPS) as a hydrophilic capping agent. PtNPs were deposited by a dipcoating technique on titania nanofibers (TiO2NFs), obtained by electrospinning. The investigated properties of the Pt-TiO2 hybrid at room temperature show that this material combines the properties of photoconduction of titania and the photocatalytic activity of the hybrid. To assess the best performance of Pt-TiO2, different measurements were performed at room temperature, comparing hydrogen response under UV of the uncoated TiO2NFs, compared with the Pt-TiO2 system prepared with two different amounts of PtNPs. During the sensing tests toward hydrogen an enhancement of photoconductivity (150%), an increase in response (400%) and an overall improvement of their dynamic behaviour were observed. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01400f

  12. Solution Studies on DNA Interactions of Substitution-inert Platinum Complexes mediated via The Phosphate Clamp

    PubMed Central

    Qu, Y.; Kipping, R. G.

    2015-01-01

    The phosphate clamp is a distinct mode of ligand-DNA binding where the molecular is manifest through (“non-covalent”) hydrogen-bonding from am(m)ines of polynuclear platinum complexes to the phosphate oxygens on the oligonucleotide backbone. This third mode of DNA is unique from the “classical” DNA intercalators and minor groove binding agents and even the closely related covalently binding mononuclear and polynuclear drugs. 2D 1H NMR studies on the Dickerson Drew Dodecamer (DDD, d(CGCGAATTCGCG)2) showed significant A-T contacts mainly on nucleotides A6, T7 and T8 implying a selective bridging from C9G10 in the 3' direction to C9G10 of the opposite strand. {1H, 15N} HSQC NMR Spectroscopy using the fully 15N-labelled compound ([{trans-Pt(NH2)3(H2N(CH2)6NH3}2μ-(H2N(CH2)6NH2)2(Pt(NH3)2]8+ (TriplatinNC) showed at pH6 significant chemical shift and 1J(195Pt-15N) coupling constants from free drug and DDD-TriplatinNC at pH 7 indicative of formation of the phosphate clamp. 31P NMR results are also reported for the hexamer d(CGTACG)2 showing changes in 31P NMR chemical shifts indicative of changes around the phosphorous center. The studies confirm the DNA binding modes by substitution-inert (non-covalent) polynuclear platinum complexes and help to further establish the chemotype as a new class of potential anti-tumor agents in their own right with a distinct profile of biological activity. PMID:25524170

  13. Catalytic Ignition and Upstream Reaction Propagation in a Platinum Tube

    NASA Technical Reports Server (NTRS)

    Struk, P. M.; Dietrich, D. L.; Mellish, B. P.; Miller, F. J.; T'ien, J. S.

    2007-01-01

    A challenge for catalytic combustion in monolithic reactors at elevated temperatures is the start-up or "light-off" from a cold initial condition. In this work, we demonstrate a concept called "back-end catalytic ignition that potentially can be utilized in the light-off of catalytic monoliths. An external downstream flame or Joule heating raises the temperature of a small portion of the catalyst near the outlet initiating a localized catalytic reaction that propagates upstream heating the entire channel. This work uses a transient numerical model to demonstrate "back-end" ignition within a single channel which can characterize the overall performance of a monolith. The paper presents comparisons to an experiment using a single non-adiabatic channel but the concept can be extended to the adiabatic monolith case. In the model, the time scales associated with solid heat-up are typically several orders of magnitude larger than the gas-phase and chemical kinetic time-scales. Therefore, the model assumes a quasi-steady gas-phase with respect to a transient solid. The gas phase is one-dimensional. Appropriate correlations, however, account for heat and mass transfer in a direction perpendicular to the flow. The thermally-thin solid includes axial conduction. The gas phase, however, does not include axial conduction due to the high Peclet number flows. The model includes both detailed gas-phase and catalytic surface reactions. The experiment utilizes a pure platinum circular channel oriented horizontally though which a CO/O2 mixture (equivalence ratios ranging from 0.6 to 0.9) flows at 2 m/s.

  14. On the system cerium-platinum-silicon

    SciTech Connect

    Gribanov, Alexander Grytsiv, Andriy; Royanian, Esmaeil; Rogl, Peter; Bauer, Ernst; Giester, Gerald; Seropegin, Yurii

    2008-11-15

    Phase relations in the ternary system Ce-Pt-Si have been established for the isothermal section at 800 deg. C based on X-ray powder diffraction, metallography, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) techniques on about 120 alloys, which were prepared by various methods employing arc-melting under argon or powder reaction sintering. Nineteen ternary compounds were observed. Atom order in the crystal structures of {tau}{sub 18}-Ce{sub 5}(Pt,Si){sub 4} (Pnma; a=0.77223(3) nm, b=1.53279(8) nm c=0.80054(5) nm), {tau}{sub 3}-Ce{sub 2}Pt{sub 7}Si{sub 4} (Pnma; a=1.96335(8) nm, b=0.40361(4) nm, c=1.12240(6) nm) and {tau}{sub 10}-CePtSi{sub 2} (Cmcm; a=0.42943(2) nm, b=1.67357(5) nm, c=0.42372(2) nm) was determined by direct methods from X-ray single-crystal CCD data and found to be isotypic with the Sm{sub 5}Ge{sub 4}-type, the Ce{sub 2}Pt{sub 7}Ge{sub 4}-type and the CeNiSi{sub 2}-type, respectively. Rietveld refinements established the atom arrangement in the structures of Pt{sub 3}Si (Pt{sub 3}Ge-type, C2/m, a=0.7724(2) nm, b=0.7767(2) nm, c=0.5390(2) nm, {beta}=133.86(2){sup o}), {tau}{sub 16}-Ce{sub 3}Pt{sub 5}Si (Ce{sub 3}Pd{sub 5}Si-type, Imma, a=0.74025(8) nm, b=1.2951(2) nm, c=0.7508(1) nm) and {tau}{sub 17}-Ce{sub 3}PtSi{sub 3} (Ba{sub 3}Al{sub 2}Ge{sub 2}-type, Immm, a=0.41065(5) nm, b=0.43221(5) nm, c=1.8375(3) nm). Phase equilibria in Ce-Pt-Si are characterised by the absence of cerium solubility in platinum silicides. Cerium silicides and cerium platinides, however, dissolve significant amounts of the third component, whereby random substitution of the almost equally sized atom species platinum and silicon is reflected in extended homogeneous regions at constant Ce content such as for {tau}{sub 13}-Ce(Pt{sub x}Si{sub 1-x}){sub 2}, {tau}{sub 6}-Ce{sub 2}Pt{sub 3+x}Si{sub 5-x} or {tau}{sub 7}-CePt{sub 2-x}Si{sub 2+x}. - Graphical abstract: Phase relations in the ternary system Ce-Pt-Si have been established for the isothermal

  15. Antiparasitic agents.

    PubMed

    Rosenblatt, J E

    1999-11-01

    Several important developments have occurred in recent years in the chemotherapy for and prophylaxis of parasitic infections. Although mefloquine is clearly the most effective agent for prevention of chloroquine-resistant falciparum malaria, its use has been compromised by side effects, both real and imagined. Well-designed studies have shown that side effects occur no more frequently with low-dose mefloquine than with chloroquine. Use of mefloquine in pregnant women has not been associated with birth defects, but the incidence of stillbirths may be increased. Malarone is a new agent that combines atovaquone and proguanil, and it may be as effective as mefloquine; however, it is not yet available in the United States. Several newer agents have appeared in response to the development of multidrug resistant Plasmodium falciparum, especially in Southeast Asia. Halofantrine is available for the treatment of mild to moderate malaria due to P. falciparum and for P. vivax infections. Because of severe toxic effects, use of halofantrine should be restricted to only those unusual and rare situations in which other agents cannot be used. Artemisinin (an extract of the Chinese herbal remedy qinghaosu) and two derivatives, artesunate and artemether, are active against multidrug resistant P. falciparum and are widely used in Asia in oral, parenteral, and rectal forms. The antibacterial azithromycin in combination with atovaquone or quinine has now been reported to treat babesiosis effectively in experimental animals and in a few patients. Azithromycin in combination with paromomycin has also shown promise in the treatment of cryptosporidiosis (and toxoplasmosis when combined with pyrimethamine) in patients with the acquired immunodeficiency syndrome (AIDS). Albendazole is currently the only systemic agent available for treatment of microsporidiosis, an infection primarily of patients with AIDS. In addition, albendazole and ivermectin have emerged as effective broad

  16. Atomic engineering of platinum alloy surfaces.

    PubMed

    Li, Tong; Bagot, P A J; Marquis, E A; Edman Tsang, S C; Smith, G D W

    2013-09-01

    A major practical challenge in heterogeneous catalysis is to minimize the loading of expensive platinum group metals (PGMs) without degrading the overall catalytic efficiency. Gaining a thorough atomic-scale understanding of the chemical/structural changes occurring during catalyst manufacture/operation could potentially enable the design and production of "nano-engineered" catalysts, optimized for cost, stability and performance. In the present study, the oxidation behavior of a Pt-31 at% Pd alloy between 673-1073 K is investigated using atom probe tomography (APT). Over this range of temperatures, three markedly different chemical structures are observed near the surface of the alloy. At 673 K, the surface oxide formed is enriched with Pd, the concentration of which rises further following oxidation at 773 K. During oxidation at 873 K, a thick, stable oxide layer is formed on the surface with a stoichiometry of PdO, beneath which a Pd-depleted (Pt-rich) layer exists. Above 873 K, the surface composition switches to enrichment in Pt, with the Pt content increasing further with increasing oxidation temperature. This treatment suggests a route for tuning the surfaces of Pt-Pd nanoparticles to be either Pd-rich or Pt-rich, simply by adjusting the oxidation temperatures in order to form two different types of core-shell structures. In addition, comparison of the oxidation behavior of Pt-Pd with Pt-Rh and Pd-Rh alloys demonstrates markedly different trends under the same conditions for these three binary alloys. PMID:23276526

  17. Transport Magnetic Proximity Effects in Platinum

    NASA Astrophysics Data System (ADS)

    Huang, Ssu-Yen

    2013-03-01

    Platinum (Pt) metal, being non-magnetic and having a strong spin-orbit coupling interaction, has been central in detecting pure spin current and establishing most of the recent spin-based phenomena. Thus, it is important to ascertain the transport and magnetic characteristics of thin Pt films in contact with a ferromagnet. In this work, we use both electric and thermal means to conclusively show the transport magnetic proximity effects (MPE) of thin Pt film in contact with ferromagnetic insulator YIG. At thicknesses comparable to, and less than, the spin diffusion length, the strong ferromagnetic characteristics in Pt films on YIG are indistinguishable from those of ferromagnetic permalloy on YIG. The MPE occurs at the interface and decreases exponentially away from the interface, concentrating in only a few monolayers. As a result, the pure spin current detected by a thin Pt is tainted with a spin polarized current. The pure spin current phenomena, such as the inverse spin Hall effect and the spin Seebeck effect, have been contaminated with the anomalous Hall effect and the anomalous Nernst effect respectively. These results raise serious questions about the suitability, and the validity, of using Pt in establishing pure spin current phenomena; on the other hand, a much stronger spin-based effect can be induced by the MPE at the interface. This research is in collaboration with X. Fin, Y. P. Chen, J. Wu, and J. Q. Xiao (University of Delaware), T. Y. Chen (Arizona State University) and D. Qu, W. G. Wang, and C. L. Chien (The Johns Hopkins University).

  18. Comparison of platinum/MWCNTs Nanocatalysts Synthesis Processes for Proton Exchange Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    Liu, Xuan

    Due to the growing concerns on the depletion of petroleum based energy resources and climate change; fuel cell technologies have received much attention in recent years. Proton exchange membrane fuel cell (PEMFCs) features high energy conversion efficiency and nearly zero greenhouse gas emissions, because of its combination of the hydrogen oxidation reaction (HOR) at anode side and oxygen reduction reaction (ORR) at cathode side. Synthesis of Pt nanoparticles supported on multi walled carbon nanotubes (MWCNTs) possess a highly durable electrochemical surface area (ESA) and show good power output on proton exchange membrane (PEM) fuel cell performance. Platinum on multi-walled carbon nanotubes (MWCNTs) support were synthesized by two different processes to transfer PtCl62- from aqueous to organic phase. While the first method of Pt/MWCNTs synthesis involved dodecane thiol (DDT) and octadecane thiol (ODT) as anchoring agent, the second method used ammonium lauryl sulfate (ALS) as the dispersion/anchoring agent. The particle size and distribution of platinum were examined by high-resolution transmission electron microscope (HRTEM). The TEM images showed homogenous distribution and uniform particle size of platinum deposited on the surface of MWCNTs. The single cell fuel cell performance of the Pt/MWCNTs synthesized thiols and ALS based electrode containing 0.2 (anode) and 0.4 mg (cathode) Pt.cm-2 were evaluated using Nafion-212 electrolyte with H2 and O2 gases at 80 °C and ambient pressure. The catalyst synthesis with ALS is relatively simple compared to that with thiols and also showed higher performance (power density reaches about 1070 mW.cm -2). The Electrodes with Pt/MWCNTs nanocatalysts synthesized using ALS were characterized by cyclic voltammetry (CV) for durability evaluation using humidified H2 and N2 gases at room temperature (21 °C) along with commercial Pt/C for comparison. The ESA measured by cyclic voltammetry between 0.15 and 1.2 V showed significant

  19. Design of experimentation with a platinum-magnesium bioelectric battery.

    PubMed

    Fontenier, G; Freschard, R; Mourot, M

    1975-01-01

    The utilization of metal electrodes in the fabrication of a bioelectric battery has been the subject of intensive study for several years. Up to this date, subcutaneous cathodes of black platinum or of silver-silver chloride have been used in conjunction with anodes of aluminum or zinc. The subcutaneous black platinum is not reliable as a function of time due to the growth of overlying heterogeneous tissues. The utilization of a smooth platinum cathode in the right endoauricular position allows good reliability with time, but does not allow using a large surface area. Furthermore we have a reduction of the H-+ ions and not of the oxygen. A pure Domal magnesium anode was utilized with this cathode, which seemed to be a good compromise between to battery's voltage, its lifetime, and its lack of toxicity to body tissues. PMID:1139023

  20. Dissolution of Platinum in the Operational Range of Fuel Cells

    PubMed Central

    Keeley, Gareth P.; Geiger, Simon; Zeradjanin, Aleksandar R.; Hodnik, Nejc; Kulyk, Nadiia

    2015-01-01

    Abstract One of the most important practical issues in low‐temperature fuel‐cell catalyst degradation is platinum dissolution. According to the literature, it initiates at 0.6–0.9 VRHE, whereas previous time‐ and potential‐resolved inductively coupled plasma mass spectrometry (ICP–MS) experiments, however, revealed dissolution onset at only 1.05 VRHE. In this manuscript, the apparent discrepancy is addressed by investigating bulk and nanoparticulated catalysts. It is shown that, given enough time for accumulation, traces of platinum can be detected at potentials as low as 0.85 VRHE. At these low potentials, anodic dissolution is the dominant process, whereas, at more positive potentials, more platinum dissolves during the oxide reduction after accumulation. Interestingly, the potential and time dissolution dependence is similar for both types of electrode. Dissolution processes are discussed with relevance to fuel‐cell operation and plausible dissolution mechanisms are considered. PMID:27525206

  1. Sum frequency generation imaging microscopy of CO on platinum.

    PubMed

    Cimatu, Katherine; Baldelli, Steven

    2006-12-20

    Sum frequency vibrational spectroscopy is utilized as an imaging technique to distinguish and compare the local response of carbon monoxide (CO) covered platinum (Pt) polycrystalline surface versus the average response of the investigated area. The Pt electrode was prepared using the standard method and was exposed to approximately 1 atm of CO(g). SFG images and vibrational spectra were obtained where the contrast is based on the intrinsic nature of each peak in the CO vibrational spectrum. The illustration of the images and the chemical maps of CO on the platinum surface showed the distribution of the CO across the observed area. The results obtained by comparing the local and the average response confirmed the spatial distributions of the CO on the platinum sample which are due to several reasons such as dipole-dipole coupling and surface coverage. This finding has a significant contribution toward recognizing that surfaces usually considered homogeneous may in fact be quite heterogeneous. PMID:17165737

  2. One-dimensional Magnus-type platinum double salts

    PubMed Central

    Hendon, Christopher H.; Walsh, Aron; Akiyama, Norinobu; Konno, Yosuke; Kajiwara, Takashi; Ito, Tasuku; Kitagawa, Hiroshi; Sakai, Ken

    2016-01-01

    Interest in platinum-chain complexes arose from their unusual oxidation states and physical properties. Despite their compositional diversity, isolation of crystalline chains has remained challenging. Here we report a simple crystallization technique that yields a series of dimer-based 1D platinum chains. The colour of the Pt2+ compounds can be switched between yellow, orange and blue. Spontaneous oxidation in air is used to form black Pt2.33+ needles. The loss of one electron per double salt results in a metallic state, as supported by quantum chemical calculations, and displays conductivity of 11 S cm−1 at room temperature. This behaviour may open up a new avenue for controllable platinum chemistry. PMID:27320502

  3. Electron Field Emission Properties of Textured Platinum Surfaces

    NASA Technical Reports Server (NTRS)

    Sovey, James S.

    2002-01-01

    During ground tests of electric microthrusters and space tests of electrodynamic tethers the electron emitters must successfully operate at environmental pressures possibly as high as 1x10(exp -4) Pa. High partial pressures of oxygen, nitrogen, and water vapor are expected in such environments. A textured platinum surface was used in this work for field emission cathode assessments because platinum does not form oxide films at low temperatures. Although a reproducible cathode conditioning process did not evolve from this work, some short term tests for periods of 1 to 4 hours showed no degradation of emission current at an electric field of 8 V/mm and background pressures of about 1x10(exp -6) Pa. Increases of background pressure by air flow to about 3x10(exp -4) Pa yield a hostile environment for the textured platinum field emission cathode.

  4. One-dimensional Magnus-type platinum double salts.

    PubMed

    Hendon, Christopher H; Walsh, Aron; Akiyama, Norinobu; Konno, Yosuke; Kajiwara, Takashi; Ito, Tasuku; Kitagawa, Hiroshi; Sakai, Ken

    2016-01-01

    Interest in platinum-chain complexes arose from their unusual oxidation states and physical properties. Despite their compositional diversity, isolation of crystalline chains has remained challenging. Here we report a simple crystallization technique that yields a series of dimer-based 1D platinum chains. The colour of the Pt(2+) compounds can be switched between yellow, orange and blue. Spontaneous oxidation in air is used to form black Pt(2.33+) needles. The loss of one electron per double salt results in a metallic state, as supported by quantum chemical calculations, and displays conductivity of 11 S cm(-1) at room temperature. This behaviour may open up a new avenue for controllable platinum chemistry. PMID:27320502

  5. 40 CFR 440.110 - Applicability; description of the platinum ore subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... platinum ore subcategory. 440.110 Section 440.110 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Platinum Ores Subcategory § 440.110 Applicability; description of the platinum ore subcategory. The provisions of...

  6. 40 CFR 440.110 - Applicability; description of the platinum ore subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... platinum ore subcategory. 440.110 Section 440.110 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Platinum Ores Subcategory § 440.110 Applicability; description of the platinum ore subcategory....

  7. 40 CFR 440.110 - Applicability; description of the platinum ore subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... platinum ore subcategory. 440.110 Section 440.110 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Platinum Ores Subcategory § 440.110 Applicability; description of the platinum ore subcategory....

  8. 40 CFR 440.110 - Applicability; description of the platinum ore subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... platinum ore subcategory. 440.110 Section 440.110 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Platinum Ores Subcategory § 440.110 Applicability; description of the platinum ore subcategory. The provisions of...

  9. 40 CFR 440.110 - Applicability; description of the platinum ore subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... platinum ore subcategory. 440.110 Section 440.110 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Platinum Ores Subcategory § 440.110 Applicability; description of the platinum ore subcategory....

  10. DETERMINATION OF HUMAN BODY BURDEN BASELINE DATA OF PLATINUM THROUGH AUTOPSY TISSUE ANALYSIS

    EPA Science Inventory

    Results of analysis for platinum in 97 autopsy sets are presented. Analysis was performed by a specially developed emission spectrochemical method. Almost half of the individuals studied were found to have detectable platinum in one or more tissue samples. Platinum was found to b...

  11. The effects of platinum on nickel electrodes in the nickel hydrogen cell

    NASA Technical Reports Server (NTRS)

    Zimmerman, Albert H.

    1991-01-01

    Interactions of platinum and platinum compounds with the nickel electrode that are possible in the nickel hydrogen cell, where both the nickel electrode and a platinum catalyst hydrogen electrode are in intimate contact with the alkaline electrolyte, are examined. Additionally, a mechanism of nickel cobalt oxyhydroxide formation in NiH2 cells is presented.

  12. New agents for prostate cancer.

    PubMed

    Agarwal, N; Di Lorenzo, G; Sonpavde, G; Bellmunt, J

    2014-09-01

    The therapeutic landscape of metastatic castration-resistant prostate cancer (mCRPC) has been revolutionized by the arrival of multiple novel agents in the past 2 years. Immunotherapy in the form of sipuleucel-T, androgen axis inhibitors, including abiraterone acetate and enzalutamide, a chemotherapeutic agent, cabazitaxel, and a radiopharmaceutical, radium-223, have all yielded incremental extensions of survival and have been recently approved. A number of other agents appear promising in early studies, suggesting that the armamentarium against castrate-resistant prostate cancer is likely to continue to expand. Emerging androgen pathway inhibitors include androgen synthesis inhibitors (TAK700), androgen receptor inhibitors (ARN-509, ODM-201), AR DNA binding domain inhibitors (EPI-001), selective AR downregulators or SARDs (AZD-3514), and agents that inhibit both androgen synthesis and receptor binding (TOK-001/galeterone). Promising immunotherapeutic agents include poxvirus vaccines and CTLA-4 inhibitor (ipilimumab). Biologic agents targeting the molecular drivers of disease are also being investigated as single agents, including cabozantinib (Met and VEGFR2 inhibitor) and tasquinimod (angiogenesis and immune modulatory agent). Despite the disappointing results seen from studies evaluating docetaxel in combination with other agents, including GVAX, anti-angiogentic agents (bevacizumab, aflibercept, lenalinomide), a SRC kinase inhibitor (dasatinib), endothelin receptor antagonists (atrasentan, zibotentan), and high-dose calcitriol (DN-101), the results from the trial evaluating docetaxel in combination with the clusterin antagonist, custirsen, are eagerly awaited. New therapeutic hurdles consist of discovering new targets, understanding resistance mechanisms, the optimal sequencing and combinations of available agents, as well as biomarkers predictive for benefit. Novel agents targeting bone metastases are being developed following the success of zoledronic acid

  13. Second EPA evaluation of the Platinum Gasaver Device under Section 511 of the Motor Vehicle Information and Cost Savings Act (updated). Technical report

    SciTech Connect

    Not Available

    1991-07-01

    The report announces the conclusions of the EPA evaluation of the Platinum Gasaver Device under the provisions of Section 511 of the Motor Vehicle Information and Cost Savings Act. The second evaluation of the Platinum Gasaver device was conducted upon the request of the Federal Trade Commission. The unit is a vapor bleed device. It functions by bleeding a mixture of air and 'platinum concentrate' through a 'T' connection that is installed in the Positive Crankcase Ventilation (PCV) line. It is claimed to reduce emissions, improve fuel economy, raise the octane of gasoline, and extend engine line. Three typical vehicles were tested at the EPA's Motor Vehicle Emission Laboratory. The basic test sequence included 2,000 miles of mileage accumulation, replicate Federal Test Procedures (FTP) and replicate Highway Fuel Economy Tests (HFET). The test sequence was conducted both without and with the Platinum Gasaver installed. The overall conclusion from these tests is that the Platinum Gasaver device did not significantly change vehicle emissions or fuel economy for either the FTP or the HFET.

  14. Predictive value of BRCA1 expression on the efficacy of chemotherapy based on anti-microtubule agents: a pooled analysis across different malignancies and agents

    PubMed Central

    He, Qihua; Zhang, Mingzhe; Zhang, Jianrong; Zhong, Shengyi; Liu, Yang; Shen, Jianfei; He, Jiaxi; Jiang, Long; Yang, Chenglin; Zeng, Yuan; Guo, Minzhang; Chen, Xuewei

    2016-01-01

    Background Breast cancer susceptibility gene 1 (BRCA1) expression has been suggested as a predictor in anti-neoplastic treatment with anti-microtubule agents. However, the existing evidence is conflicting. Consulting the literature, we sought to examine the true impact of BRCA1 expression on the efficacy of anti-microtubule agents. Methods Medline by PubMed and Embase databases were searched for eligible studies. The primary endpoints were objective response rate (ORR) and progression free survival (PFS). Additional subgroup analyses stratified for detection methods, regimen, and patient origin were also performed. Results A total of 13 relevant studies involving a total of 1,490 cases were enrolled. Involved agents included paclitaxel, docetaxel and vinorelbine; Malignancies included non-small cell lung cancer, gastric cancer, esophageal carcinoma, ovarian carcinoma, malignant pleural mesothelioma, breast cancer, and small cell lung cancer. Through meta-analyses, we observed a potentially greater ORR in the population with high BRCA1 expression vs. low BRCA1 expression (OR 1.63, 95% CI: 0.92 to 2.88, P=0.09) but the heterogeneity is severe (P=0.01; I2=61%). Similar results were observed in PFS (high vs. low expression, HR 0.93, 95% CI: 0.75 to 1.15, P=0.49; heterogeneity, P<0.01, I2=75%). After stratification by testing methods, a significantly higher ORR in the population with high BRCA1 expression was shown in the subgroup using mRNA as a quantitative method (OR 2.90, 95% CI: 1.92 to 4.39, P<0.01; I2=0) whereas the difference in the subgroup using immunohistochemistry (IHC) was not significant (OR 0.60, 95% CI: 0.33 to 1.10, P=0.10; I2=0). Stratification by regimen (platinum-based vs. non platinum-based) and patient origin (Asian vs. Caucasian) did not reduce the heterogeneity. Conclusions Although the predictive value of BRCA1 expression on the anti-microtubule chemotherapy remained uncertain based on overall results, our exploratory analyses suggested that

  15. Synthesis of platinum nanoparticle electrocatalysts by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Lubers, Alia Marie

    Demand for energy continues to increase, and without alternatives to fossil fuel combustion the effects on our environment will become increasingly severe. Fuel cells offer a promising improvement on current methods of energy generation; they are able to convert hydrogen fuel into electricity with a theoretical efficiency of up to 83% and interface smoothly with renewable hydrogen production. Fuel cells can replace internal combustion engines in vehicles and are used in stationary applications to power homes and businesses. The efficiency of a fuel cell is maximized by its catalyst, which is often composed of platinum nanoparticles supported on carbon. Economical production of fuel cell catalysts will promote adoption of this technology. Atomic layer deposition (ALD) is a possible method for producing catalysts at a large scale when employed in a fluidized bed. ALD relies on sequential dosing of gas-phase precursors to grow a material layer by layer. We have synthesized platinum nanoparticles on a carbon particle support (Pt/C) by ALD for use in proton exchange membrane fuel cells (PEMFCs) and electrochemical hydrogen pumps. Platinum nanoparticles with different characteristics were deposited by changing two chemistries: the carbon substrate through functionalization; and the deposition process by use of either oxygen or hydrogen as ligand removing reactants. The metal depositing reactant was trimethyl(methylcyclopentadienyl)platinum(IV). Functionalizing the carbon substrate increased nucleation during deposition resulting in smaller and more dispersed nanoparticles. Use of hydrogen produced smaller nanoparticles than oxygen, due to a gentler hydrogenation reaction compared to using oxygen's destructive combustion reaction. Synthesized Pt/C materials were used as catalysts in an electrochemical hydrogen pump, a device used to separate hydrogen fuel from contaminants. Catalysts deposited by ALD on functionalized carbon using a hydrogen chemistry were the most

  16. Temperature dependence of the emissivity of platinum in the IR.

    PubMed

    Deemyad, Shanti; Silvera, Isaac F

    2008-08-01

    The accuracy of temperature determination by fitting the spectral irradiance to a Planck curve depends on knowledge of the emissivity at all temperatures and pressures of interest within a spectral region. Here, the emissivity of platinum is measured in the near infrared as a function of temperature. In the wavelength range of study and the temperature range of 650-1100 K, we find the emissivity to be independent of temperature to within experimental error. This result should lead to improved accuracy of temperature measurement by optical pyrometry where platinum is used as a thermal emitter. PMID:19044386

  17. Determination of palladium and platinum by atomic absorption

    USGS Publications Warehouse

    Schnepfe, M.M.; Grimaldi, F.S.

    1969-01-01

    Palladium and platinum are determined by atomic absorption after fire-assay concentration into a gold bead. The limit of determination is ~0??06 ppm in a 20-g sample. Serious depressive interelement interferences are removed by buffering the solutions with a mixture of cadmium and copper sulphates with cadmium and copper concentrations each at 0??5%. Substantial amounts of Ag, Al, Au, Bi, Ca, Co, Cr, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, Pb, Te, Ti, V, Y, Zn, and the platinum metals do not interfere in the atomic-absorption determination. ?? 1969.

  18. Amphiphilic Cyanine-Platinum Conjugates as Fluorescent Nanodrugs.

    PubMed

    Sun, Tingting; Li, Zhensheng; Xie, Zhigang; Jing, Xiabin

    2016-01-01

    Two fluorescent nanomedicines based on small molecular cyanine-platinum conjugates have been prepared via a nanoprecipitation method and characterized by transmission electron microscopy (TEM) as well as dynamic light scattering (DLS). The conjugates exhibited an enhanced fluorescence in their nanoparticle formulation compared to that in solution. The nanomedicines could be endocytosed by cancer cells as revealed by confocal laser scanning microscopy (CLSM) and showed high cellular proliferation inhibition. Fluorescent platinum nanomedicines prepared directly from small molecules could be an alternative strategy for developing new drugs with simultaneous cellular imaging and cancer therapy functions. PMID:26556434

  19. Cytoreductive surgery followed by chemotherapy versus chemotherapy alone for recurrent platinum-sensitive epithelial ovarian cancer (SOCceR trial): a multicenter randomised controlled study

    PubMed Central

    2014-01-01

    Background Improvement in treatment for patients with recurrent ovarian cancer is needed. Standard therapy in patients with platinum-sensitive recurrent ovarian cancer consists of platinum-based chemotherapy. Median overall survival is reported between 18 and 35 months. Currently, the role of surgery in recurrent ovarian cancer is not clear. In selective patients a survival benefit up to 62 months is reported for patients undergoing complete secondary cytoreductive surgery. Whether cytoreductive surgery in recurrent platinum-sensitive ovarian cancer is beneficial remains questionable due to the lack of level I-II evidence. Methods/Design Multicentre randomized controlled trial, including all nine gynecologic oncologic centres in the Netherlands and their affiliated hospitals. Eligible patients are women, with first recurrence of FIGO stage Ic-IV platinum-sensitive epithelial ovarian cancer, primary peritoneal cancer or fallopian tube cancer, who meet the inclusion criteria. Participants are randomized between the standard treatment consisting of at least six cycles of intravenous platinum based chemotherapy and the experimental treatment which consists of secondary cytoreductive surgery followed by at least six cycles of intravenous platinum based chemotherapy. Primary outcome measure is progression free survival. In total 230 patients will be randomized. Data will be analysed according to intention to treat. Discussion Where the role of cytoreductive surgery is widely accepted in the initial treatment of ovarian cancer, its value in recurrent platinum-sensitive epithelial ovarian cancer has not been established so far. A better understanding of the benefits and patients selection criteria for secondary cytoreductive surgery has to be obtained. Therefore the 4th ovarian cancer consensus conference in 2010 stated that randomized controlled phase 3 trials evaluating the role of surgery in platinum-sensitive recurrent epithelial ovarian cancer are urgently needed. We

  20. KGB agents

    NASA Astrophysics Data System (ADS)

    Gaina, Alex

    A short story is reported in which the activity of Communist Party of the USSR and secret KGB agents, which were payed by the State, in view of controlling of the conscience of population. The story reffers to the Physics Department of the Moscow University, Planing Institute of the Gosplan of Moldavian S.S.R. and Chishinau Technical University (actually: Technical University of Moldova), where the author has worked during Soviet times. Almost every 6-th citizen in the USSR was engaged in this activity, while actually the former communists rule in the Republic of Moldova.

  1. Microwave spectroscopy of platinum monofluoride and platinum monochloride in the X 2Π(3/2) states.

    PubMed

    Okabayashi, Toshiaki; Kurahara, Taku; Okabayashi, Emi Y; Tanimoto, Mitsutoshi

    2012-05-01

    Platinum monofluoride (PtF) and platinum monochloride (PtCl) were detected in the gas phase using a source-modulated microwave spectrometer. The PtF and PtCl radicals were generated in a free space cell using the sputtering reaction from a platinum sheet placed on the inner surface of a stainless steel cathode through a dc glow discharge plasma of CF(4) and Cl(2), respectively, diluted with Ar. Rotational transitions were measured in the region between 150 and 313 GHz. Rotational, centrifugal distortion, and several fine- and hyperfine-structure constants were determined by a least-squares analysis. The observed fine-structure spectral patterns indicate that both PtF and PtCl radicals have the (2)Π(3/2) electronic ground states, while the related cyanide PtCN and hydride PtH radicals have the (2)Δ(5/2) electronic ground states. PMID:22583234

  2. Recent strikes in South Africa’s platinum-group metal mines: effects upon world platinum-group metal supplies

    USGS Publications Warehouse

    Yager, Thomas R.; Soto-Viruet, Yadira; Barry, James J.

    2012-01-01

    The recent labor disputes over wages and working conditions that have affected South Africa’s three leading platinum-group metal (PGM) producers have affected an industry already plagued by market pressures and labor unrest and raised the specter of constraints in the world’s supply of these metals. Although low demand for these metals in 2011 and 2012 helped to offset production losses of recent years, and particularly those losses caused by the strikes in 2012, a prolonged resumption of strikes could cause severe shortages of iridium, platinum, rhodium, ruthenium, and, to a lesser extent, palladium.

  3. Optimization of carbon-supported platinum cathode catalysts for DMFC operation.

    SciTech Connect

    Zhu, Y.; Brosha, E. L.; Zelenay, P.

    2002-01-01

    In this paper, we describe performance and optimization of carbon-supported cathode catalysts at low platinum loading. We find that at a loading below 0.6 mg cm-2 carbon-supported platinum outperforms platinum black as a DMFC cathode catalyst. A catalyst with a 1:1 volume ratio of the dry NafionTM to the electronically conducting phase (platinum plus carbon support) provides the best performance in oxygen reduction reaction. Thanks to improved catalyst utilization, carbon-supported catalysts with a platinum content varying from 40 wt% to 80 wt% deliver very good DMFC performance, even at relatively modest precious metal loadings investigated in this work.

  4. Platinum-group elements in the Eastern Deccan volcanic province and a comparison with platinum metals of the western Deccan

    NASA Astrophysics Data System (ADS)

    Crocket, James; Paul, Dalim; Lala, Trisha

    2013-08-01

    This study is the first detailed investigation of the platinum-group elements (PGE) at the eastern margin of the Deccan volcanic province of India. One of the PGE, osmium, is not included largely because of analytical problems. The study is focused on mafic volcanics and dykes from four areas including Amarkantak, Umaria, Shahdol and Chirimiri. The first two localities represent two lava piles of about 170 and 400 m thickness respectively. In Umaria, 16 flows have been demarcated based on petrography and field studies. The Shahdol samples are basal lava formations overlying Gondwana sediments (Carboniferous) and the Chirimiri samples are dykes. In this study, the western Deccan province is defined as the Western Ghats plus Kutch. On average, the PGE are ~20% higher in Amarkantak than Umaria and the flows are ~13% higher in PGE than the dykes. A Zr vs. Pd scattergram found a strong positive correlation for these two elements except for one Umaria sample which indicated severe Pd loss. A comparison of west and east parts of the Deccan volcanic province using primitive mantle normalization showed that higher values prevailed in the western province suite in the Ni-Ir-Ru-Pt region. In contrast, eastern province values dominated in the Pd-Au-Cu region at the `Cu' end of the profiles. A strong dominance of Pd in the eastern Deccan was also of interest. A number of factors, for example, percentage partial melting of the source rock and the temperature and pressure of partial melting strongly influence the character of these profiles. The observed PGE profile characteristics probably result in part from a long distance of subsurface transport of Deccan magma from the western to eastern regions.

  5. Oxalato-platinum or 1-OHP, a third-generation platinum complex: an experimental and clinical appraisal and preliminary comparison with cis-platinum and carboplatinum.

    PubMed

    Mathé, G; Kidani, Y; Segiguchi, M; Eriguchi, M; Fredj, G; Peytavin, G; Misset, J L; Brienza, S; de Vassals, F; Chenu, E

    1989-01-01

    A new platinum complex, oxalatoplatin or l-OHP, which, at the same metal dose in experimental tests is as efficient as cisplatin, and is more so at a lower metal dose than carboplatin; which is as efficient in human tumors of the testis and ovary as these other analogs, and more so in melanoma and breast cancer; which is not nephrotoxic, cardiotoxic or mutagenic, and hardly hematotoxic and neurotoxic, is described and compared with the above-mentioned platinum complexes. Combined with 5Fu, it induces a high number of remissions in colorectal cancer, and has brought about cures in inoperable gastric cancers. Combined with carboplatin, it has resulted in a high proportion of cures in L1210-carrying mice, which no other two-by-two combination of these complexes has achieved. PMID:2675999

  6. Agent independent task planning

    NASA Technical Reports Server (NTRS)

    Davis, William S.

    1990-01-01

    Agent-Independent Planning is a technique that allows the construction of activity plans without regard to the agent that will perform them. Once generated, a plan is then validated and translated into instructions for a particular agent, whether a robot, crewmember, or software-based control system. Because Space Station Freedom (SSF) is planned for orbital operations for approximately thirty years, it will almost certainly experience numerous enhancements and upgrades, including upgrades in robotic manipulators. Agent-Independent Planning provides the capability to construct plans for SSF operations, independent of specific robotic systems, by combining techniques of object oriented modeling, nonlinear planning and temporal logic. Since a plan is validated using the physical and functional models of a particular agent, new robotic systems can be developed and integrated with existing operations in a robust manner. This technique also provides the capability to generate plans for crewmembers with varying skill levels, and later apply these same plans to more sophisticated robotic manipulators made available by evolutions in technology.

  7. Adjuvant platinum-based chemotherapy for early stage cervical cancer

    PubMed Central

    Rosa, Daniela D; Medeiros, Lídia RF; Edelweiss, Maria I; Pohlmann, Paula R; Stein, Airton T

    2014-01-01

    Background This is an updated version of the original Cochrane review published in The Cochrane Library 2009, Issue 3. Most women with early cervical cancer (stages I to IIA) are cured with surgery or radiotherapy, or both. We performed this review originally because it was unclear whether cisplatin-based chemotherapy after surgery, radiotherapy or both, in women with early stage disease with risk factors for recurrence, was associated with additional survival benefits or risks. Objectives To evaluate the effectiveness and safety of platinum-based chemotherapy after radical hysterectomy, radiotherapy, or both in the treatment of early stage cervical cancer. Search methods For the original 2009 review, we searched the Cochrane Gynaecological Cancer Group Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library 2009, Issue 1), MEDLINE, EMBASE, LILACS, BIOLOGICAL ABSTRACTS and CancerLit, the National Research Register and Clinical Trials register, with no language restriction. We handsearched abstracts of scientific meetings and other relevant publications. We extended the database searches to November 2011 for this update. Selection criteria Randomised controlled trials (RCTs) comparing adjuvant cisplatin-based chemotherapy (after radical surgery, radiotherapy or both) with no adjuvant chemotherapy, in women with early stage cervical cancer (stage IA2-IIA) with at least one risk factor for recurrence. Data collection and analysis Two review authors extracted data independently. Meta-analysis was performed using a random-effects model, with death and disease progression as outcomes. Main results For this updated version, we identified three additional ongoing trials but no new studies for inclusion. Three trials including 368 evaluable women with early cervical cancer were included in the meta-analyses. The median follow-up period in these trials ranged from 29 to 42 months. All women had undergone surgery first. Two trials

  8. Biological role in the transformation of platinum-group mineral grains

    NASA Astrophysics Data System (ADS)

    Reith, Frank; Zammit, Carla M.; Shar, Sahar S.; Etschmann, Barbara; Bottrill, Ralph; Southam, Gordon; Ta, Christine; Kilburn, Matthew; Oberthür, Thomas; Ball, Andrew S.; Brugger, Joël

    2016-04-01

    Platinum-group elements are strategically important metals. Finding new deposits is becoming increasingly difficult owing to our limited understanding of the processes that affect their mobility in surface environments. Microorganisms have been shown to promote the mobility of metals around ore deposits. Here we show that microorganisms influence the mobility of platinum-group elements in mineral grains collected from Brazil, Australia and Colombia. Scanning electron microscopy showed biofilms covering the platinum-group mineral grains. The biofilms contained abundant platinum-group element nanoparticles and microcrystalline aggregates, and were dominated by Proteobacteria, many of which were closely related to known metal-resistant species. Some platinum-group mineral grains contained carbon, nitrogen, sulfur, selenium and iodine, suggesting the grains may be biogenic in origin. Molecular analyses show that Brazilian platinum-palladium grains hosted specific bacterial communities, which were different in composition from communities associated with gold grains, or communities in surrounding soils and sediments. Nano-phase metallic platinum accumulated when a metallophillic bacterium was incubated with a percolating platinum-containing medium, suggesting that biofilms can cause the precipitation of mobile platinum complexes. We conclude that biofilms are capable of forming or transforming platinum-group mineral grains, and may play an important role for platinum-group element dispersion and re-concentration in surface environments.

  9. Aligned platinum nanowire networks from surface-oriented lipid cubic phase templates

    NASA Astrophysics Data System (ADS)

    Richardson, S. J.; Burton, M. R.; Staniec, P. A.; Nandhakumar, I. S.; Terrill, N. J.; Elliott, J. M.; Squires, A. M.

    2016-01-01

    Mesoporous metal structures featuring a bicontinuous cubic morphology have a wide range of potential applications and novel opto-electronic properties, often orientation-dependent. We describe the production of nanostructured metal films 1-2 microns thick featuring 3D-periodic `single diamond' morphology that show high out-of-plane alignment, with the (111) plane oriented parallel to the substrate. These are produced by electrodeposition of platinum through a lipid cubic phase (QII) template. Further investigation into the mechanism for the orientation revealed the surprising result that the QII template, which is tens of microns thick, is polydomain with no overall orientation. When thicker platinum films are grown, they also show increased orientational disorder. These results suggest that polydomain QII samples display a region of uniaxial orientation at the lipid/substrate interface up to approximately 2.8 +/- 0.3 μm away from the solid surface. Our approach gives previously unavailable information on the arrangement of cubic phases at solid interfaces, which is important for many applications of QII phases. Most significantly, we have produced a previously unreported class of oriented nanomaterial, with potential applications including metamaterials and lithographic masks.Mesoporous metal structures featuring a bicontinuous cubic morphology have a wide range of potential applications and novel opto-electronic properties, often orientation-dependent. We describe the production of nanostructured metal films 1-2 microns thick featuring 3D-periodic `single diamond' morphology that show high out-of-plane alignment, with the (111) plane oriented parallel to the substrate. These are produced by electrodeposition of platinum through a lipid cubic phase (QII) template. Further investigation into the mechanism for the orientation revealed the surprising result that the QII template, which is tens of microns thick, is polydomain with no overall orientation. When thicker

  10. Density Functional Study of the Structure, Stability and Oxygen Reduction Activity of Ultrathin Platinum Nanowires

    SciTech Connect

    Matanovic, Ivana; Kent, Paul; Garzon, Fernando; Henson, Neil J.

    2013-03-14

    We used density functional theory to study the difference in the structure, stability and catalytic reactivity between ultrathin, 0.5–1.0 nm diameter, platinum nanotubes and nanowires. Model nanowires were formed by inserting an inner chain of platinum atoms in small diameter nanotubes. In this way more stable, non-hollow structures were formed. The difference in the electronic structure of platinum nanotubes and nanowires was examined by inspecting the density of surface states and band structure. Furthermore, reactivity toward the oxygen reduction reaction of platinum nanowires was assessed by studying the change in the chemisorption energies of oxygen, hydroxyl, and hydroperoxyl groups, induced by converting the nanotube models to nanowires. Both ultrathin platinum nanotubes and nanowires show distinct properties compared to bulk platinum. Single-wall nanotubes and platinum nanowires with diameters larger than 1 nm show promise for use as oxygen reduction catalysts.

  11. Synthesis, Characterization, and Catalytic Properties of Novel Single-Site and Nanosized Platinum Catalysts

    SciTech Connect

    Bonati, Matteo L.M.; Douglas, Thomas M.; Gaemers, Sander; Guo, Neng

    2013-01-10

    Novel single-site platinum catalysts have been synthesized by reacting platinum(II) organometallics with partially dehydroxylated silica. The resulting materials have been characterized by various methods such as IR, MAS NMR, and EXAFS. Further, the single-site platinum catalysts were calcined in air to remove the ligand and produce nanosized platinum particles, that were characterized by TEM and H{sub 2} chemisorption. All catalysts were tested for the hydrogenation of toluene. The single-site platinum catalysts were less active than a commercial Pt/SiO{sub 2} catalyst with comparable platinum loading, and this has been ascribed to ligand effects. Conversely, the nanosized platinum catalysts were more active than the commercial Pt/SiO{sub 2} catalyst due to their high dispersion and small particle sizes.

  12. Theoretical Study of the Structure, Stability and Oxygen Reduction Activity of Ultrathin Platinum Nanowires

    SciTech Connect

    Matanovic, Ivana; Kent, Paul; Garzon, Fernando; Henson, Neil J.

    2012-10-10

    We use density functional theory to study the difference in the structure, stability and catalytic reactivity between ultrathin, 0.5- 1.0 nm diameter, platinum nanotubes and nanowires. Model nanowires were formed by inserting an inner chain of platinum atoms in small diameter nanotubes. In this way more stable, nonhollow structures were formed. The difference in the electronic structure of platinum nanotubes and nanowires was examined by inspecting the density of surface states and band structure. Furthermore, reactivity towards the oxygen reduction reaction of platinum nanowires was addressed by studying the change in the chemisorption energies of oxygen and hydroxyl groups, induced by inserting the inner chain of platinum atoms into the hollow nanotubes. Both ultrathin platinum nanotubes and nanowires show distinct properties compared to bulk platinum. Nanotubes with diameters larger than 1 nm show promise for use as oxygen reduction catalysts.

  13. Single-Atom Catalyst of Platinum Supported on Titanium Nitride for Selective Electrochemical Reactions.

    PubMed

    Yang, Sungeun; Kim, Jiwhan; Tak, Young Joo; Soon, Aloysius; Lee, Hyunjoo

    2016-02-01

    As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single-atom platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for the oxygen-reduction reaction toward a two-electron pathway and formic acid oxidation toward direct dehydrogenation, and also induced no activity for the methanol oxidation. This work demonstrates that single-atom platinum can be an efficient electrocatalyst with high mass activity and unique selectivity. PMID:26710326

  14. Gelled Anti-icing Agents

    NASA Technical Reports Server (NTRS)

    Markles, O. F.; Sperber, H. H.

    1983-01-01

    Pectin added to antifreeze/water mixture. Formulations include water with dimethyl sulfoxide (DMSO) as deicer and pectin as gel former. Without gelling agent, deicer runs off vertical surfaces. Without pectin solution will completely evaporate in far less time. Agents developed have wide potential for ice prevention on runways, highways, bridges and sidewalks.

  15. Enhancement of Platinum Cathode Catalysis by Addition of Transition Metals

    ERIC Educational Resources Information Center

    Duong, Hung Tuan

    2009-01-01

    The sluggish kinetics of oxygen reduction reaction (ORR) contributes significantly to the loss of cathode overpotential in fuel cells, thus requiring high loadings of platinum (Pt), which is an expensive metal with limited supply. However, Pt and Pt-based alloys are still the best available electrocatalysts for ORR thus far. The research presented…

  16. Responses of fibroblasts and glial cells to nanostructured platinum surfaces

    NASA Astrophysics Data System (ADS)

    Pennisi, C. P.; Sevcencu, C.; Dolatshahi-Pirouz, A.; Foss, M.; Lundsgaard Hansen, J.; Nylandsted Larsen, A.; Zachar, V.; Besenbacher, F.; Yoshida, K.

    2009-09-01

    The chronic performance of implantable neural prostheses is affected by the growth of encapsulation tissue onto the stimulation electrodes. Encapsulation is associated with activation of connective tissue cells at the electrode's metallic contacts, usually made of platinum. Since surface nanotopography can modulate the cellular responses to materials, the aim of the present work was to evaluate the 'in vitro' responses of connective tissue cells to platinum strictly by modulating its surface nanoroughness. Using molecular beam epitaxy combined with sputtering, we produced platinum nanostructured substrates consisting of irregularly distributed nanopyramids and investigated their effect on the proliferation, cytoskeletal organization and cellular morphology of primary fibroblasts and transformed glial cells. Cells were cultured on these substrates and their responses to surface roughness were studied. After one day in culture, the fibroblasts were more elongated and their cytoskeleton less mature when cultured on rough substrates. This effect increased as the roughness of the surface increased and was associated with reduced cell proliferation throughout the observation period (4 days). Morphological changes also occurred in glial cells, but they were triggered by a different roughness scale and did not affect cellular proliferation. In conclusion, surface nanotopography modulates the responses of fibroblasts and glial cells to platinum, which may be an important factor in optimizing the tissue response to implanted neural electrodes.

  17. Operation of platinum-palladium catalysts with leaded gasoline.

    PubMed Central

    Teague, D M; Clougherty, L B; Speca, A N

    1975-01-01

    The effect of various fuel additives on the ability of platinum-palladium catalytic converters to remove the carbon monoxide and hydrocarbon components of automotive exhaust has been examined. Engine dynamometer studies suggest that these catalysts may be successfully used in conjunction with fuels of relatively high tetraethyllead concentrations, provided the ethylene dibromide portion of the scavenger is excluded. PMID:50929

  18. Operation of platinum-palladium catalysts with leaded gasoline.

    PubMed

    Teague, D M; Clougherty, L B; Speca, A N

    1975-04-01

    The effect of various fuel additives on the ability of platinum-palladium catalytic converters to remove the carbon monoxide and hydrocarbon components of automotive exhaust has been examined. Engine dynamometer studies suggest that these catalysts may be successfully used in conjunction with fuels of relatively high tetraethyllead concentrations, provided the ethylene dibromide portion of the scavenger is excluded. PMID:50929

  19. Rapid epitaxy-free graphene synthesis on silicidated polycrystalline platinum

    PubMed Central

    Babenko, Vitaliy; Murdock, Adrian T.; Koós, Antal A.; Britton, Jude; Crossley, Alison; Holdway, Philip; Moffat, Jonathan; Huang, Jian; Alexander-Webber, Jack A.; Nicholas, Robin J.; Grobert, Nicole

    2015-01-01

    Large-area synthesis of high-quality graphene by chemical vapour deposition on metallic substrates requires polishing or substrate grain enlargement followed by a lengthy growth period. Here we demonstrate a novel substrate processing method for facile synthesis of mm-sized, single-crystal graphene by coating polycrystalline platinum foils with a silicon-containing film. The film reacts with platinum on heating, resulting in the formation of a liquid platinum silicide layer that screens the platinum lattice and fills topographic defects. This reduces the dependence on the surface properties of the catalytic substrate, improving the crystallinity, uniformity and size of graphene domains. At elevated temperatures growth rates of more than an order of magnitude higher (120 μm min−1) than typically reported are achieved, allowing savings in costs for consumable materials, energy and time. This generic technique paves the way for using a whole new range of eutectic substrates for the large-area synthesis of 2D materials. PMID:26175062

  20. Molybdenum-platinum-oxide electrodes for thermoelectric generators

    DOEpatents

    Schmatz, Duane J.

    1990-01-01

    The invention is directed to a composite article suitable for use in thermoelectric generators. The article comprises a solid electrolyte carrying a thin film comprising molybdenum-platinum-oxide as an electrode deposited by physical deposition techniques. The invention is also directed to the method of making same.

  1. Platinum Recovery from Synthetic Extreme Environments by Halophilic Bacteria.

    PubMed

    Maes, Synthia; Props, Ruben; Fitts, Jeffrey P; Smet, Rebecca De; Vilchez-Vargas, Ramiro; Vital, Marius; Pieper, Dietmar H; Vanhaecke, Frank; Boon, Nico; Hennebel, Tom

    2016-03-01

    Metal recycling based on urban mining needs to be established to tackle the increasing supply risk of critical metals such as platinum. Presently, efficient strategies are missing for the recovery of platinum from diluted industrial process streams, often characterized by extremely low pHs and high salt concentrations. In this research, halophilic mixed cultures were employed for the biological recovery of platinum (Pt). Halophilic bacteria were enriched from Artemia cysts, living in salt lakes, in different salt matrices (sea salt mixture and NH4Cl; 20-210 g L(-1) salts) and at low to neutral pH (pH 3-7). The main taxonomic families present in the halophilic cultures were Halomonadaceae, Bacillaceae, and Idiomarinaceae. The halophilic cultures were able to recover >98% Pt(II) and >97% Pt(IV) at pH 2 within 3-21 h (4-453 mg Ptrecovered h(-1) g(-1) biomass). X-ray absorption spectroscopy confirmed the reduction to Pt(0) and transmission electron microscopy revealed both intra- and extracellular Pt precipitates, with median diameters of 9-30 nm and 11-13 nm, for Pt(II) and Pt(IV), respectively. Flow cytometric membrane integrity staining demonstrated the preservation of cell viability during platinum recovery. This study demonstrates the Pt recovery potential of halophilic mixed cultures in acidic saline conditions. PMID:26854514

  2. Concentration of some platinum-group metals in coal

    USGS Publications Warehouse

    Finkelman, R.B.; Aruscavage, P. J.

    1981-01-01

    New data on some platinum group metals in coal indicate that the concentration of Pt is generally less than about 5 ppb, that of Pd is generally less than 1 ppb, and that of Rh is generally less than 0.5 ppb. No conclusive evidence was obtained concerning the mode of occurrence of these elements in coal. ?? 1981.

  3. Binding of Kinetically Inert Metal Ions to RNA: The Case of Platinum(II)

    PubMed Central

    Chapman, Erich G.; Hostetter, Alethia A.; Osborn, Maire F.; Miller, Amanda L.; DeRose, Victoria J.

    2014-01-01

    In this chapter several aspects of Pt(II) are highlighted that focus on the properties of Pt(II)-RNA adducts and the possibility that they influence RNA-based processes in cells. Cellular distribution of Pt(II) complexes results in significant platination of RNA, and localization studies find Pt(II) in the nucleus, nucleolus, and a distribution of other sites in cells. Treatment with Pt(II) compounds disrupts RNA-based processes including enzymatic processing, splicing, and translation, and this disruption may be indicative of structural changes to RNA or RNA-protein complexes. Several RNA-Pt(II) adducts have been characterized in vitro by biochemical and other methods. Evidence for Pt(II) binding in non-helical regions and for Pt(II) cross-linking of internal loops has been found. Although platinated sites have been identified, there currently exists very little in the way of detailed structural characterization of RNA-Pt(II) adducts. Some insight into the details of Pt(II) coordination to RNA, especially RNA helices, can be gained from DNA model systems. Many RNA structures, however, contain complex tertiary folds and common, purine-rich structural elements that present suitable Pt(II) nucleophiles in unique arrangements which may hold the potential for novel types of platinum-RNA adducts. Future research aimed at structural characterization of platinum-RNA adducts may provide further insights into platinum-nucleic acid binding motifs, and perhaps provide a rationale for the observed inhibition by Pt(II) complexes of splicing, translation, and enzymatic processing. PMID:22010278

  4. Partial Response in an RRx-001-Primed Patient with Refractory Small-Cell Lung Cancer after a Third Introduction of Platinum Doublets

    PubMed Central

    Carter, Corey A.; Oronsky, Bryan; Caroen, Scott; Scicinski, Jan; Degesys, Aiste; Cabrales, Pedro; Reid, Tony R.; Brzezniak, Christina

    2016-01-01

    Small-cell lung cancer (SCLC), initially exquisitely sensitive to first-line cisplatin/etoposide, invariably relapses and acquires a multidrug chemoresistant phenotype that generally renders retreatment with first-line therapy both futile and counterproductive. This report presents the case of a 77-year-old Caucasian male with extensive-stage refractory SCLC who was restarted on platinum doublets as part of a clinical trial called TRIPLE THREAT (NCT02489903) involving pretreatment with the epi-immunotherapeutic agent RRx-001, and who achieved a partial response after only 4 cycles. The patient had received a platinum drug twice before, in 2009 for a diagnosis of non-small-cell lung cancer (squamous cell carcinoma) and in 2015 for SCLC, suggesting that RRx-001 pretreatment may sensitize or resensitize refractory SCLC patients to first-line chemotherapy. PMID:27403127

  5. Chromatin folding and DNA replication inhibition mediated by a highly antitumor-active tetrazolato-bridged dinuclear platinum(II) complex

    PubMed Central

    Imai, Ryosuke; Komeda, Seiji; Shimura, Mari; Tamura, Sachiko; Matsuyama, Satoshi; Nishimura, Kohei; Rogge, Ryan; Matsunaga, Akihiro; Hiratani, Ichiro; Takata, Hideaki; Uemura, Masako; Iida, Yutaka; Yoshikawa, Yuko; Hansen, Jeffrey C.; Yamauchi, Kazuto; Kanemaki, Masato T.; Maeshima, Kazuhiro

    2016-01-01

    Chromatin DNA must be read out for various cellular functions, and copied for the next cell division. These processes are targets of many anticancer agents. Platinum-based drugs, such as cisplatin, have been used extensively in cancer chemotherapy. The drug–DNA interaction causes DNA crosslinks and subsequent cytotoxicity. Recently, it was reported that an azolato-bridged dinuclear platinum(II) complex, 5-H-Y, exhibits a different anticancer spectrum from cisplatin. Here, using an interdisciplinary approach, we reveal that the cytotoxic mechanism of 5-H-Y is distinct from that of cisplatin. 5-H-Y inhibits DNA replication and also RNA transcription, arresting cells in the S/G2 phase, and are effective against cisplatin-resistant cancer cells. Moreover, it causes much less DNA crosslinking than cisplatin, and induces chromatin folding. 5-H-Y will expand the clinical applications for the treatment of chemotherapy-insensitive cancers. PMID:27094881

  6. Chromatin folding and DNA replication inhibition mediated by a highly antitumor-active tetrazolato-bridged dinuclear platinum(II) complex.

    PubMed

    Imai, Ryosuke; Komeda, Seiji; Shimura, Mari; Tamura, Sachiko; Matsuyama, Satoshi; Nishimura, Kohei; Rogge, Ryan; Matsunaga, Akihiro; Hiratani, Ichiro; Takata, Hideaki; Uemura, Masako; Iida, Yutaka; Yoshikawa, Yuko; Hansen, Jeffrey C; Yamauchi, Kazuto; Kanemaki, Masato T; Maeshima, Kazuhiro

    2016-01-01

    Chromatin DNA must be read out for various cellular functions, and copied for the next cell division. These processes are targets of many anticancer agents. Platinum-based drugs, such as cisplatin, have been used extensively in cancer chemotherapy. The drug-DNA interaction causes DNA crosslinks and subsequent cytotoxicity. Recently, it was reported that an azolato-bridged dinuclear platinum(II) complex, 5-H-Y, exhibits a different anticancer spectrum from cisplatin. Here, using an interdisciplinary approach, we reveal that the cytotoxic mechanism of 5-H-Y is distinct from that of cisplatin. 5-H-Y inhibits DNA replication and also RNA transcription, arresting cells in the S/G2 phase, and are effective against cisplatin-resistant cancer cells. Moreover, it causes much less DNA crosslinking than cisplatin, and induces chromatin folding. 5-H-Y will expand the clinical applications for the treatment of chemotherapy-insensitive cancers. PMID:27094881

  7. Radiosensitization of EMT6 cells by four platinum complexes.

    PubMed

    Teicher, B A; Rockwell, S; Lee, J B

    1985-05-01

    The greatest research effort in producing radiation sensitizers has been directed toward organic compounds. However, platinum complexes also have radiosensitizing capabilities, perhaps because they bind to DNA. The compound described here are dichloro complexes of bivalent platinum with one or two potentially radiosensitizing ligands. The radiosensitization of oxygenated and hypoxic exponentially growing EMT6 cells in vitro was measured. The dose modifying factors obtained with 200 microM and 400 microM trans-bis(2-nitroimidazole)dichloroplatinum II (NIPt) in hypoxic cells were 1.5 and 2.1, respectively. For trans-bis(2-amino-5-nitrothiazole)dichloroplatinum II (Plant) under the same conditions, the dose modifying factor was 1.5 at 200 microM and 1.8 at 400 microM. Neither compound sensitized oxygenated cells when tested similar protocols. Unlike the trans complexes, (1,2-diamino-4-nitrobenzene)dichloroplatinum II (Plato) was cytotoxic toward the hypoxic cells in the absence of X rays. The time course of cytotoxicity for 100 microM Plato in exponentially growing cells showed rapid killing of hypoxic cells, and much less toxicity toward oxygenated cells. In radiosensitization studies, dose modifying factors of 1.6 and 2.0 were found with 200 microM and 400 microM Plato in hypoxic cells. The compound did not sensitize aerobic cells. The well-known platinum complex cis-dipyridinedichloroplatinum II (PyPt) represents a cis-platinum heterocyclic aromatic complex that does not have a nitro-functionality. The dose modifying factor obtained with 400 microM PyPt in hypoxic cells was 1.7. On a molar basis, the nitro-functional platinum complexes appear to be more effective as hypoxic cell radiosensitizers than the corresponding free ligands. PMID:4039304

  8. Health care agents

    MedlinePlus

    Durable power of attorney for health care; Health care proxy; End-of-life - health care agent; Life support treatment - ... Respirator - health care agent; Ventilator - health care agent; Power of attorney - health care agent; POA - health care ...

  9. Platinum mineralization in the Kapalagulu Intrusion, western Tanzania

    NASA Astrophysics Data System (ADS)

    Wilhelmij, Harry R.; Cabri, Louis J.

    2016-03-01

    . Impersistent, stratiform PGE mineralized horizons occur within the MCSS harzburgite from which drill core samples were taken for platinum-group mineral (PGM) characterization from two drill holes. Where the PGE reefs reach the surface there is residual PGE mineralization within the laterite regolith from which drill core samples were taken from various laterite lithological units for PGM characterization. As the harzburgite PGE reefs contain significant concentrations of both sulfide and chromite (including chromitite seams) they resemble the PGE-rich chromitite seams of the Bushveld Complex rather than the PGE-bearing Main Sulfide Zone of the Great Dyke and Main Sulfide Layer of the Munni Munni Complex. The dominant Pd PGM in three PGE reef samples varies, ranging ( n = 164, relative wt%) from bismuthides (63 %), bismuthtellurides (19 %), and tellurides (6 %), to tellurides (39 %), bismuthtellurides (24 %), stannides (14 %), and alloys (13 %), and to antimon-arsenides (33 %), stannides (21 %), bismuthides (17 %), tellurides (13 %), and alloys (10 %). From 13.5 % to 21.0 % of the total Pd occurs as a solid solution in pentlandite. The three samples have similar Pt PGM modal distributions ( n = 172, relative wt%); the dominant Pt mineral is sperrylite (79, 58, and 47 %) followed by tellurides (15, 17, 21 %), alloys (2, 1, 1 %), and sulfides (2, 1, 0 %). Comparison of Pd/Pt ratios from assays to those calculated from minerals show that the data for the Pt and Pd PGM are very robust, confirming the concentration methodology and characterization. Study of samples from a shallow drill hole penetrating the laterite regolith shows that the primary Pd mineralization has not survived oxidation, is mainly dispersed, but some was reconstituted to form secondary minerals: cabriite, unnamed tellurides, a selenide, a Pd-Te-Hg mineral, alloys and Pd-bearing secondary sulfides (millerite and heazlewoodite). The primary Pt minerals are more resistant to oxidation and dissolution, especially

  10. Platinum mineralization in the Kapalagulu Intrusion, western Tanzania

    NASA Astrophysics Data System (ADS)

    Wilhelmij, Harry R.; Cabri, Louis J.

    2016-03-01

    . Impersistent, stratiform PGE mineralized horizons occur within the MCSS harzburgite from which drill core samples were taken for platinum-group mineral (PGM) characterization from two drill holes. Where the PGE reefs reach the surface there is residual PGE mineralization within the laterite regolith from which drill core samples were taken from various laterite lithological units for PGM characterization. As the harzburgite PGE reefs contain significant concentrations of both sulfide and chromite (including chromitite seams) they resemble the PGE-rich chromitite seams of the Bushveld Complex rather than the PGE-bearing Main Sulfide Zone of the Great Dyke and Main Sulfide Layer of the Munni Munni Complex. The dominant Pd PGM in three PGE reef samples varies, ranging ( n = 164, relative wt%) from bismuthides (63 %), bismuthtellurides (19 %), and tellurides (6 %), to tellurides (39 %), bismuthtellurides (24 %), stannides (14 %), and alloys (13 %), and to antimon-arsenides (33 %), stannides (21 %), bismuthides (17 %), tellurides (13 %), and alloys (10 %). From 13.5 % to 21.0 % of the total Pd occurs as a solid solution in pentlandite. The three samples have similar Pt PGM modal distributions ( n = 172, relative wt%); the dominant Pt mineral is sperrylite (79, 58, and 47 %) followed by tellurides (15, 17, 21 %), alloys (2, 1, 1 %), and sulfides (2, 1, 0 %). Comparison of Pd/Pt ratios from assays to those calculated from minerals show that the data for the Pt and Pd PGM are very robust, confirming the concentration methodology and characterization. Study of samples from a shallow drill hole penetrating the laterite regolith shows that the primary Pd mineralization has not survived oxidation, is mainly dispersed, but some was reconstituted to form secondary minerals: cabriite, unnamed tellurides, a selenide, a Pd-Te-Hg mineral, alloys and Pd-bearing secondary sulfides (millerite and heazlewoodite). The primary Pt minerals are more resistant to oxidation and dissolution, especially

  11. Battlefield agent collaboration

    NASA Astrophysics Data System (ADS)

    Budulas, Peter P.; Young, Stuart H.; Emmerman, Philip J.

    2001-09-01

    Small air and ground physical agents (robots) will be ubiquitous on the battlefield of the 21st century, principally to lower the exposure to harm of our ground forces in urban and open terrain scenarios. Teams of small collaborating physical agents conducting tasks such as Reconnaissance, Surveillance, and Target Acquisition (RSTA), intelligence, chemical and biological agent detection, logistics, decoy, sentry; and communications relay will have advanced sensors, communications, and mobility characteristics. It is anticipated that there will be many levels of individual and team collaboration between the soldier and robot, robot to robot, and robot to mother ship. This paper presents applications and infrastructure components that illustrate each of these levels. As an example, consider the application where a team of twenty small robots must rapidly explore and define a building complex. Local interactions and decisions require peer to peer collaboration. Global direction and information fusion warrant a central team control provided by a mother ship. The mother ship must effectively deliver/retrieve, service, and control these robots as well as fuse the information gathered by these highly mobile robot teams. Any level of collaboration requires robust communications, specifically a mobile ad hoc network. The application of fixed ground sensors and mobile robots is also included in this paper. This paper discusses on going research at the U.S. Army Research Laboratory that supports the development of multi-robot collaboration. This research includes battlefield visualization, intelligent software agents, adaptive communications, sensor and information fusion, and multi-modal human computer interaction.

  12. TISSUE ORGAN DISTRIBUTION AND BEHAVIORAL EFFECTS OF PLATINUM FOLLOWING ACUTE AND REPEATED EXPOSURE OF THE MOUSE TO PLATINUM SULFATE

    EPA Science Inventory

    Platinum sulfate was administered intragastrically (IG) to adult male Swiss mice in a single dose at the 7 day LD5 or LD25 level. Control groups received 0.25M H2SO4 (pH 0.85) or 0.14M NaCl. Open field behavior (ambulations, rearings) was measured, and tissue/organ Pt levels dete...

  13. Iron(III)-Salophene: An Organometallic Compound with Selective Cytotoxic and Anti-Proliferative Properties in Platinum-Resistant Ovarian Cancer Cells

    PubMed Central

    Singh, Rakesh K.; Strongin, Robert M.; McCourt, Carolyn K.; Brard, Laurent

    2008-01-01

    Background In this pioneer study to the biological activity of organometallic compound Iron(III)-salophene (Fe-SP) the specific effects of Fe-SP on viability, morphology, proliferation, and cell-cycle progression on platinum-resistant ovarian cancer cell lines were investigated. Methodology/Principal Findings Fe-SP displayed selective cytotoxicity against SKOV-3 and OVCAR-3 (ovarian epithelial adenocarcinoma) cell lines at concentrations between 100 nM and 1 µM, while the viability of HeLa cells (epithelial cervix adenocarcinoma) or primary lung or skin fibroblasts was not affected. SKOV-3 cells in contrast to fibroblasts after treatment with Fe-SP revealed apparent hallmarks of apoptosis including densely stained nuclear granular bodies within fragmented nuclei, highly condensed chromatin and chromatin fragmentation. Fe-SP treatment led to the activation of markers of the extrinsic (Caspase-8) and intrinsic (Caspase-9) pathway of apoptosis as well as of executioner Caspase-3 while PARP-1 was deactivated. Fe-SP exerted effects as an anti-proliferative agent with an IC50 value of 300 nM and caused delayed progression of cells through S-phase phase of the cell cycle resulting in a complete S-phase arrest. When intra-peritoneally applied to rats Fe-SP did not show any systemic toxicity at concentrations that in preliminary trials were determined to be chemotherapeutic relevant doses in a rat ovarian cancer cell model. Conclusion/Significance The present report suggests that Fe-SP is a potent growth-suppressing agent in vitro for cell lines derived from ovarian cancer and a potential therapeutic drug to treat such tumors in vivo. PMID:18509533

  14. Agent Building Software

    NASA Technical Reports Server (NTRS)

    2000-01-01

    AgentBuilder is a software component developed under an SBIR contract between Reticular Systems, Inc., and Goddard Space Flight Center. AgentBuilder allows software developers without experience in intelligent agent technologies to easily build software applications using intelligent agents. Agents are components of software that will perform tasks automatically, with no intervention or command from a user. AgentBuilder reduces the time and cost of developing agent systems and provides a simple mechanism for implementing high-performance agent systems.

  15. Candidate pathway-based genetic association study of Platinum and Platinum-Taxane Related Toxicity in a Cohort of Primary Lung Cancer Patients

    PubMed Central

    Johnson, Cassandra; Pankratz, Vernon S.; Velazquez, Ana I.; Aakre, Jeremiah A.; Loprinzi, Charles L.; Staff, Nathan P.; Windebank, Anthony J.; Yang, Ping

    2015-01-01

    Background Chemotherapy-induced peripheral neuropathy (CIPN) is a common toxicity secondary to chemotherapy. Genetic factors may be important in predisposing patients to this adverse effect. Patients and Methods We studied 950 primary lung cancer patients, who received platinum or platinum-combination drug chemotherapy and who had DNA available for study. We analyzed epidemiological risk factors in 279 CIPN patients and 456 non-CIPN patients and genetic risk factors in 141 CIPN patients and 259 non-CIPN patients. The risk factors studied included demographic, diagnostic, and treatment data, as well as 174 tag SNPs (single nucleotide polymorphisms) across 43 candidate genes in the glutathione, cell cycle, DNA repair, cell signaling, and apoptosis pathways. Results Patients who had diabetes mellitus were more likely to have CIPN (p=0.0002). Other epidemiologic risk factors associated with CIPN included number of cycles (p=0.0004) and type of concurrent chemotherapy (p<0.001) . SNPs most associated with CIPN were in glutathione peroxidase 7 (GPX7) gene (p values 0.0015 and 0.0028, unadjusted and adjusted) and in ATP-binding cassette sub-family C member 4 (ABCC4) gene (p values 0.037 and 0.006, unadjusted and adjusted). We also found other suggestive associations in methyl-o-guanine-methyl-transferase (MGMT) and glutathione-S-transferase (GST) isoforms. Conclusions Epidemiological and genetic risk factors associated with CIPN in this cohort, included the type of chemotherapy drug, intensity of chemotherapy treatment, and genes known to be associated with chemotherapy resistance. These findings suggest that differentiating between cytotoxic and neurotoxic mechanisms of chemotherapy drugs is challenging but represents an important step toward individualized therapy and improving quality of life for patients. PMID:25586538

  16. Transdermal delivery of therapeutic agent

    NASA Technical Reports Server (NTRS)

    Kwiatkowski, Krzysztof C. (Inventor); Hayes, Ryan T. (Inventor); Magnuson, James W. (Inventor); Giletto, Anthony (Inventor)

    2008-01-01

    A device for the transdermal delivery of a therapeutic agent to a biological subject that includes a first electrode comprising a first array of electrically conductive microprojections for providing electrical communication through a skin portion of the subject to a second electrode comprising a second array of electrically conductive microprojections. Additionally, a reservoir for holding the therapeutic agent surrounding the first electrode and a pulse generator for providing an exponential decay pulse between the first and second electrodes may be provided. A method includes the steps of piercing a stratum corneum layer of skin with two arrays of conductive microprojections, encapsulating the therapeutic agent into biocompatible charged carriers, surrounding the conductive microprojections with the therapeutic agent, generating an exponential decay pulse between the two arrays of conductive microprojections to create a non-uniform electrical field and electrokinetically driving the therapeutic agent through the stratum corneum layer of skin.

  17. Nanomechanical properties of platinum thin films synthesized by atomic layer deposition

    SciTech Connect

    Mamun, M.A.; Gu, D.; Baumgart, H.; Elmustafa, A.A.

    2015-03-01

    The nanomechanical properties of Pt thin films grown on Si (100) using atomic layer deposition (ALD) were investigated using nanoindentation. Recently, atomic layer deposition (ALD) has successfully demonstrated the capability to deposit ultra-thin films of platinum (Pt). Using (methylcyclopentadienyl) trimethylplatinum (MeCpPtMe3) as chemical platinum precursor and oxygen (O2) as the oxidizing agent, the ALD synthesis of Pt can be achieved with high conformity and excellent film uniformity. The ALD process window for Pt films was experimentally established in the temperature range between 270 °C and 320 °C, where the sheet conductance was constant over that temperature range, indicating stable ALD Pt film growth rate. ALD growth of Pt films exhibits very poor nucleation and adhesion characteristics on bare Si surfaces when the native oxide was removed by 2% HF etch. Pt adhesion improves for thermally oxidized Si wafers and for Si wafers covered with native oxide. Three ALD Pt films deposited at 800, 900, and 1000 ALD deposition cycles were tested for the structural and mechanical properties. Additionally, the sample with 900 ALD deposition cycles was further annealed in forming gas (95% N2 and 5% H2) at 450 °C for 30 min in order to passivate dangling bonds in the grain boundaries of the polycrystalline Pt film. Cross-sectional transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscope (SEM) were employed to characterize the films' surface structure and morphology. Nanoindentation technique was used to evaluate the hardness and modulus of the ALD Pt films of various film thicknesses. The results indicate that the films depict comparable hardness and modulus results; however, the 800 and 1000 ALD deposition cycles films without forming gas annealing experienced significant amount of pileup, whereas the 900 ALD deposition cycles sample annealed in forming gas resulted in a smaller pileup.

  18. Platinum-based chemotherapy in triple-negative advanced breast cancer.

    PubMed

    Villarreal-Garza, Cynthia; Khalaf, Daniel; Bouganim, Nathaniel; Clemons, Mark; Peña-Curiel, Omar; Baez-Revueltas, Berenice; Kiss, Alexander; Kassam, Farah; Enright, Katherine; Verma, Sunil; Pritchard, Kathleen; Myers, Jeff; Dent, Rebecca

    2014-08-01

    The purpose of this study was to evaluate the efficacy of platinum-based chemotherapy (PBC) versus conventional non-PBC regimens in a metastatic triple-negative breast cancer (TNBC) setting. We reviewed the electronic patient records of patients with confirmed metastatic TNBC at four major cancer centres in Canada. All patients were allocated into two groups based on type of chemotherapy received (PBC vs. non-PBC) and line of treatment (first-, second-, or third-line). The primary objective of this study was to evaluate the efficacy of PBC in metastatic TNBC in terms of median duration of overall survival (OS) from diagnosis of distant metastatic disease and compare it with the efficacy of conventional non-platinum-based chemotherapy in metastatic TNBC after controlling for known prognostic factors. A total of 153 metastatic TNBC patients were identified, 58 treated with PBC and 95 with non-PBC. The median time in first-line PBC versus non-PBC was not different between the two groups (2 vs. 2 months, p = 0.9), the median time on treatment in second and third-line therapy was longer for the PBC group compared to the conventional treated group (4 vs. 1 months, p = 0.004; 4 vs. 0.5 months, p = 0.004, respectively). Patients who received PBC had a longer OS compared to those managed conventionally (14.5 vs. 10 months, p = 0.041). This study evaluates the survival outcomes in a homogenous group of TNBC metastatic patients treated with or without PBC. Our results confirmed our hypothesis of a better OS among PBC-treated TNBC patients compared to conventionally managed TNBC patients. Currently ongoing Phase III trials assessing the benefit of PBC versus other chemotherapeutic regimens in advanced TNBC will help define the role of these agents for the management of this breast cancer subtype. PMID:25001611

  19. Organic Cation Transporters Modulate the Uptake and Cytotoxicity of Picoplatin, a Third-Generation Platinum Analogue

    PubMed Central

    More, Swati S.; Li, Shuanglian; Yee, Sook Wah; Chen, Ligong; Xu, Zhidong; Jablons, David M.; Giacomini, Kathleen M.

    2012-01-01

    Picoplatin, a third-generation platinum agent, is efficacious against lung cancers that are otherwise resistant or become refractory during platinum treatment. This effort was aimed at the determination of the influence of organic cation transporters 1, 2, and 3 (OCT1, OCT2, and OCT3) and their genetic variants on cellular uptake of picoplatin and on the individual components of the ensuing cytotoxicity such as DNA adduct formation. The effect of OCT1 on picoplatin pharmacokinetics and antitumor efficacy was determined using OCT knockout mice and HEK293 xenografts stably expressing OCT1. The uptake and DNA adduct formation of picoplatin were found to be significantly enhanced by the expression of the OCTs. Expression of OCT1 and OCT2, but not OCT3, significantly enhanced picoplatin cytotoxicity, which was reduced in the presence of an OCT inhibitor. Common reduced functional variants of OCT1 and OCT2 led to reduction in uptake and DNA adduct formation of picoplatin in comparison with the reference OCT1 and OCT2. Pharmacokinetic parameters of picoplatin in Oct1−/− and Oct1+/+ mice were not significantly different, suggesting that the transporters do not influence the disposition of the drug. In contrast, the volume of OCT1-expressing xenografts in mice was significantly reduced by picoplatin treatment, suggesting that OCT1 may enhance the antitumor efficacy of picoplatin. These studies provide a basis for follow-up clinical studies that would seek to examine the relationship between the anticancer efficacy of picoplatin and expression levels of OCTs and their genetic variants in tumors. PMID:20371711

  20. Anomalously high retention of radiogenic helium in native platinum

    NASA Astrophysics Data System (ADS)

    Yakubovich, O. V.; Shukolyukov, Yu. A.; Mochalov, A. G.; Kotov, A. B.; Korneev, S. I.

    2012-04-01

    Relatively quick migration of helium from crystal structures has been known for a long time. However there is a group of minerals - native metals - where stability of radiogenic helium is essentially high [1]. Helium, due to its very low solubility in metals, assembles in atomic clusters - "bubbles" of nanometer size. Migration of helium "bubbles" as a whole from the crystal structures needs relatively high temperature near the melting point of metals. On that ground of special interest are platinoids with melting points (and, consequently, temperatures of "explosion-like" release of radiogenic helium) of more than 1550 oC In this respect we believe that the method based on natural radioactivity of platinum is promising. To verify the idea of anomalously high retention of radiogenic helium in native platinum and to check the efficiency of the proposed 190Pt-4He method of isotope geochronology, we studied independent mineral aggregates of native platinum from chromite-bearing dunites of Galmoenan plutonic complex (10 individual samples) (Koryak-Kamchatka belt, Russia) and Konder massif (5 individual samples) (Khabarovsk district,Russia). Because native platinum always has admixture of Fe, Cu etc. for reliable determination of concentration of platinum in the samples in our study we used electron microscope JSM-6510LA with JED 2200 add-on. Amount of 4He in native platinum was determinate on mass-spectrometer complex MSU-G-01-M. Native platinum consists of 6 isotopes. Among them two isotopes are α-radioactive and decay according to following schemes: 190Pt →4He+186Os→4He+182W 192Pt →4He+188Os Presumably, in native platinum there is always a certain amount of uranium and thorium, absorbed in the process of crystallization. However influence of helium generation from uranium becomes more marked at growing of 238U/Pt ratio and beginning with 238U/Pt ≈ 10-5 should be taken into consideration. For the same reason helium produced by the decay of 192Pt and 186Os can

  1. Anti-cancer effects of newly developed chemotherapeutic agent, glycoconjugated palladium (II) complex, against cisplatin-resistant gastric cancer cells

    PubMed Central

    2013-01-01

    Background Cisplatin (CDDP) is the most frequently used chemotherapeutic agent for various types of advanced cancer, including gastric cancer. However, almost all cancer cells acquire resistance against CDDP, and this phenomenon adversely affects prognosis. Thus, new chemotherapeutic agents that can overcome the CDDP-resistant cancer cells will improve the survival of advanced cancer patients. Methods We synthesized new glycoconjugated platinum (II) and palladium (II) complexes, [PtCl2 (L)] and [PdCl2 (L)]. CDDP-resistant gastric cancer cell lines were established by continuous exposure to CDDP, and gene expression in the CDDP-resistant gastric cancer cells was analyzed. The cytotoxicity and apoptosis induced by [PtCl2 (L)] and [PdCl2 (L)] in CDDP-sensitive and CDDP-resistant gastric cancer cells were evaluated. DNA double-strand breaks by drugs were assessed by evaluating phosphorylated histone H2AX. Xenograft tumor mouse models were established and antitumor effects were also examined in vivo. Results CDDP-resistant gastric cancer cells exhibit ABCB1 and CDKN2A gene up-regulation, as compared with CDDP-sensitive gastric cancer cells. In the analyses of CDDP-resistant gastric cancer cells, [PdCl2 (L)] overcame cross-resistance to CDDP in vitro and in vivo. [PdCl2 (L)] induced DNA double-strand breaks. Conclusion These results indicate that [PdCl2 (L)] is a potent chemotherapeutic agent for CDDP-resistant gastric cancer and may have clinical applications. PMID:23672493

  2. Facile Fabrication of Platinum Nanodots Assembly Core-Silica Shell Nanosystems

    NASA Astrophysics Data System (ADS)

    Kostyukova, Diana; Yoo, Hyojong

    2016-05-01

    Nanosystems using a platinum (Pt) nanodots assembly (multi-Pt nanoparticles, m-Pt) as the core and silica (SiO2) shells were successfully synthesized as m-Pt@SiO2 spherical nanoparticles (NPs) and m-Pt@SiO2 nanochains (NChs) by a reverse microemulsion (water-in-oil)-based method. The kinetically controlled reduction of K2PtCl4 by the Brij35 surfactant within reverse micelles, followed by condensation of tetraethyl orthosilicate, led to the formation of multi-Pt nanodots core-silica shell systems. The reduction kinetics for the growth of core-shell systems was studied in both the presence of reducing agents such as ascorbic acid, glucose, and ethylene glycol and in the absence of supplementary agents, as well as the variation of water-to-surfactant ratio. To assemble Pt NPs within a one-dimensional SiO2 matrix, we attempted to grow Pt NPs in situ while the SiO2 materials grew one-dimensionally in a modified microemulsion system. By changing the pH of the reaction media or using highly concentrated ethylene glycol in the synthetic approach, we successfully synthesized m-Pt@SiO2 NChs.

  3. 1.7 nm platinum nanoparticles: synthesis with glucose starch, characterization and catalysis.

    PubMed

    Engelbrekt, Christian; Sørensen, Karsten Holm; Lübcke, Teis; Zhang, Jingdong; Li, Qingfeng; Pan, Chao; Bjerrum, Niels J; Ulstrup, Jens

    2010-09-10

    Monodisperse platinum nanoparticles (PtNPs) were synthesized by a green recipe. Glucose serves as a reducing agent and starch as a stabilization agent to protect the freshly formed PtNP cores in buffered aqueous solutions. Among the ten buffers studied, 2-(N-morpholino)ethanesulfonic acid (MES), ammonium acetate and phosphate are the best media for PtNP size control and fast chemical preparation. The uniform sizes of the metal cores were determined by transmission electron microscopy (TEM) and found to be 1.8 ± 0.5, 1.7 ± 0.2 and 1.6 ± 0.5 nm in phosphate, MES and ammonium acetate buffer, respectively. The estimated total diameter of the core with a starch coating layer is 5.8-6.0 nm, based on thermogravimetric analysis (TGA). The synthesis reaction is simple, environmentally friendly, highly reproducible, and easy to scale up. The PtNPs were characterized electrochemically and show high catalytic activity for reduction of dioxygen and hydrogen peroxide as well as for oxidation of dihydrogen. The PtNPs can be transferred to carbon support materials with little demand for high specific surface area of carbon. This enables utilization of graphitized carbon blacks to prepare well-dispersed Pt/C catalysts, which exhibit significantly improved durability in the accelerated aging test under fuel cell mimicking conditions. PMID:20715275

  4. Highly active oxygen reduction non-platinum group metal electrocatalyst without direct metal-nitrogen coordination

    NASA Astrophysics Data System (ADS)

    Strickland, Kara; Miner, Elise; Jia, Qingying; Tylus, Urszula; Ramaswamy, Nagappan; Liang, Wentao; Sougrati, Moulay-Tahar; Jaouen, Frédéric; Mukerjee, Sanjeev

    2015-06-01

    Replacement of noble metals in catalysts for cathodic oxygen reduction reaction with transition metals mostly create active sites based on a composite of nitrogen-coordinated transition metal in close concert with non-nitrogen-coordinated carbon-embedded metal atom clusters. Here we report a non-platinum group metal electrocatalyst with an active site devoid of any direct nitrogen coordination to iron that outperforms the benchmark platinum-based catalyst in alkaline media and is comparable to its best contemporaries in acidic media. In situ X-ray absorption spectroscopy in conjunction with ex situ microscopy clearly shows nitrided carbon fibres with embedded iron particles that are not directly involved in the oxygen reduction pathway. Instead, the reaction occurs primarily on the carbon-nitrogen structure in the outer skin of the nitrided carbon fibres. Implications include the potential of creating greater active site density and the potential elimination of any Fenton-type process involving exposed iron ions culminating in peroxide initiated free-radical formation.

  5. Identification of cisplatin-binding proteins using agarose conjugates of platinum compounds.

    PubMed

    Karasawa, Takatoshi; Sibrian-Vazquez, Martha; Strongin, Robert M; Steyger, Peter S

    2013-01-01

    Cisplatin is widely used as an antineoplastic drug, but its ototoxic and nephrotoxic side-effects, as well as the inherent or acquired resistance of some cancers to cisplatin, remain significant clinical problems. Cisplatin's selectivity in killing rapidly proliferating cancer cells is largely dependent on covalent binding to DNA via cisplatin's chloride sites that had been aquated. We hypothesized that cisplatin's toxicity in slowly proliferating or terminally differentiated cells is primarily due to drug-protein interactions, instead of drug-DNA binding. To identify proteins that bind to cisplatin, we synthesized two different platinum-agarose conjugates, one with two amino groups and another with two chlorides attached to platinum that are available for protein binding, and conducted pull-down assays using cochlear and kidney cells. Mass spectrometric analysis on protein bands after gel electrophoresis and Coomassie blue staining identified several proteins, including myosin IIA, glucose-regulated protein 94 (GRP94), heat shock protein 90 (HSP90), calreticulin, valosin containing protein (VCP), and ribosomal protein L5, as cisplatin-binding proteins. Future studies on the interaction of these proteins with cisplatin will elucidate whether these drug-protein interactions are involved in ototoxicity and nephrotoxicity, or contribute to tumor sensitivity or resistance to cisplatin treatment. PMID:23755301

  6. Identification of Cisplatin-Binding Proteins Using Agarose Conjugates of Platinum Compounds

    PubMed Central

    Karasawa, Takatoshi; Sibrian-Vazquez, Martha; Strongin, Robert M.; Steyger, Peter S.

    2013-01-01

    Cisplatin is widely used as an antineoplastic drug, but its ototoxic and nephrotoxic side-effects, as well as the inherent or acquired resistance of some cancers to cisplatin, remain significant clinical problems. Cisplatin's selectivity in killing rapidly proliferating cancer cells is largely dependent on covalent binding to DNA via cisplatin's chloride sites that had been aquated. We hypothesized that cisplatin's toxicity in slowly proliferating or terminally differentiated cells is primarily due to drug-protein interactions, instead of drug-DNA binding. To identify proteins that bind to cisplatin, we synthesized two different platinum-agarose conjugates, one with two amino groups and another with two chlorides attached to platinum that are available for protein binding, and conducted pull-down assays using cochlear and kidney cells. Mass spectrometric analysis on protein bands after gel electrophoresis and Coomassie blue staining identified several proteins, including myosin IIA, glucose-regulated protein 94 (GRP94), heat shock protein 90 (HSP90), calreticulin, valosin containing protein (VCP), and ribosomal protein L5, as cisplatin-binding proteins. Future studies on the interaction of these proteins with cisplatin will elucidate whether these drug-protein interactions are involved in ototoxicity and nephrotoxicity, or contribute to tumor sensitivity or resistance to cisplatin treatment. PMID:23755301

  7. Highly active oxygen reduction non-platinum group metal electrocatalyst without direct metal–nitrogen coordination

    PubMed Central

    Strickland, Kara; Miner, Elise; Jia, Qingying; Tylus, Urszula; Ramaswamy, Nagappan; Liang, Wentao; Sougrati, Moulay-Tahar; Jaouen, Frédéric; Mukerjee, Sanjeev

    2015-01-01

    Replacement of noble metals in catalysts for cathodic oxygen reduction reaction with transition metals mostly create active sites based on a composite of nitrogen-coordinated transition metal in close concert with non-nitrogen-coordinated carbon-embedded metal atom clusters. Here we report a non-platinum group metal electrocatalyst with an active site devoid of any direct nitrogen coordination to iron that outperforms the benchmark platinum-based catalyst in alkaline media and is comparable to its best contemporaries in acidic media. In situ X-ray absorption spectroscopy in conjunction with ex situ microscopy clearly shows nitrided carbon fibres with embedded iron particles that are not directly involved in the oxygen reduction pathway. Instead, the reaction occurs primarily on the carbon–nitrogen structure in the outer skin of the nitrided carbon fibres. Implications include the potential of creating greater active site density and the potential elimination of any Fenton-type process involving exposed iron ions culminating in peroxide initiated free-radical formation. PMID:26059552

  8. Antibody fragment-conjugated polymeric micelles incorporating platinum drugs for targeted therapy of pancreatic cancer.

    PubMed

    Ahn, Jooyeon; Miura, Yutaka; Yamada, Naoki; Chida, Tsukasa; Liu, Xueying; Kim, Ahram; Sato, Ryuta; Tsumura, Ryo; Koga, Yoshikatsu; Yasunaga, Masahiro; Nishiyama, Nobuhiro; Matsumura, Yasuhiro; Cabral, Horacio; Kataoka, Kazunori

    2015-01-01

    Antibody-mediated therapies including antibody-drug conjugates (ADCs) have shown much potential in cancer treatment by tumor-targeted delivery of cytotoxic drugs. However, there is a limitation of payloads that can be delivered by ADCs. Integration of antibodies to drug-loaded nanocarriers broadens the applicability of antibodies to a wide range of therapeutics. Herein, we developed antibody fragment-installed polymeric micelles via maleimide-thiol conjugation for selectively delivering platinum drugs to pancreatic tumors. By tailoring the surface density of maleimide on the micelles, one tissue factor (TF)-targeting Fab' was conjugated to each carrier. Fab'-installed platinum-loaded micelles exhibited more than 15-fold increased cellular binding within 1 h and rapid cellular internalization compared to non-targeted micelles, leading to superior in vitro cytotoxicity. In vivo, Fab'-installed micelles significantly suppressed the growth of pancreatic tumor xenografts for more than 40 days, outperforming non-targeted micelles and free drugs. These results indicate the potential of Fab'-installed polymeric micelles for efficient drug delivery to solid tumors. PMID:25477168

  9. Effect of Oligomer Length on Photophysical Properties of Platinum Acetylide Donor-Acceptor-Donor Oligomers.

    PubMed

    Cekli, Seda; Winkel, Russell W; Schanze, Kirk S

    2016-07-21

    We report a systematic study that explores how the triplet excited state is influenced by conjugation length in a series of benzothiadiazole units containing donor-acceptor-donor (DAD)-type platinum acetylide oligomers and polymer. The singlet and triplet excited states for the series were characterized by an array of photophysical methods including steady-state luminescence spectroscopy and femtosecond-nanosecond transient absorption spectroscopy. In addition to the experimental work, a computational study using density functional theory was conducted to gain more information about the structure, composition, and energies of the frontier molecular orbitals. It is observed that both the singlet and triplet excited states are mainly localized on a single donor-acceptor-donor unit in the oligomers. Interestingly, it is discovered that the intersystem crossing efficiency increases dramatically in the longer oligomers. The effect is attributed to an enhanced contribution of the heavy metal platinum in the frontier orbitals (HOMO and LUMO), an effect that leads to enhanced spin-orbit coupling. PMID:27291712

  10. Quantitative imaging of platinum based on laser ablation-inductively coupled plasma-mass spectrometry to investigate toxic side effects of cisplatin.

    PubMed

    Köppen, C; Reifschneider, O; Castanheira, I; Sperling, M; Karst, U; Ciarimboli, G

    2015-12-01

    This work presents a quantitative bioimaging method for platinum based on laser ablation-inductively coupled plasma-mass spectrometry and its application for a biomedical study concerning toxic side effects of cisplatin. To trace the histopathology back to cisplatin, platinum was localized and quantified in major functional units of testicle, cochlea, kidney, nerve and brain sections from cisplatin treated mice. The direct consideration of the histology enables precise interpretation of the Pt images and the novel quantitative evaluation approach allows significantly more precise investigations than the pure image. For the first time, platinum was detected and quantified in all major injured structures including organ of Corti of cochlea and seminiferous tubule of testicle. In this way, proximal tubule in kidney, Leydig cells in testicle, stria vascularis and organ of Corti in cochlea and nerve fibers in sciatic nerves are confirmed as targets of cisplatin in these organs. However, the accumulation of platinum in almost all investigated structures also raises questions about more complex pathogenesis including direct and indirect interruption of several biological processes. PMID:26477751

  11. A radiosonde using a humidity sensor array with a platinum resistance heater and multi-sensor data fusion.

    PubMed

    Shi, Yunbo; Luo, Yi; Zhao, Wenjie; Shang, Chunxue; Wang, Yadong; Chen, Yinsheng

    2013-01-01

    This paper describes the design and implementation of a radiosonde which can measure the meteorological temperature, humidity, pressure, and other atmospheric data. The system is composed of a CPU, microwave module, temperature sensor, pressure sensor and humidity sensor array. In order to effectively solve the humidity sensor condensation problem due to the low temperatures in the high altitude environment, a capacitive humidity sensor including four humidity sensors to collect meteorological humidity and a platinum resistance heater was developed using micro-electro-mechanical-system (MEMS) technology. A platinum resistance wire with 99.999% purity and 0.023 mm in diameter was used to obtain the meteorological temperature. A multi-sensor data fusion technique was applied to process the atmospheric data. Static and dynamic experimental results show that the designed humidity sensor with platinum resistance heater can effectively tackle the sensor condensation problem, shorten response times and enhance sensitivity. The humidity sensor array can improve measurement accuracy and obtain a reliable initial meteorological humidity data, while the multi-sensor data fusion technique eliminates the uncertainty in the measurement. The radiosonde can accurately reflect the meteorological changes. PMID:23857263

  12. A single subexcitation-energy electron can induce a double-strand break in DNA modified by platinum chemotherapeutic drugs.

    PubMed

    Rezaee, Mohammad; Alizadeh, Elahe; Cloutier, Pierre; Hunting, Darel J; Sanche, Léon

    2014-06-01

    The sensitization of malignant cells to ionizing radiation is the clinical rationale for the use of platinum-drug-based concurrent chemoradiotherapy (CCRT) for cancer treatment; however, the specific mechanisms of radiosensitization and their respective contributions still remain unknown. Biological mechanisms such as inhibition of DNA repair may contribute to the efficacy of CCRT; nevertheless, there is a dearth of information on the possible contribution of nanoscopic mechanisms to the generation of lethal DNA lesions, such as double-strand breaks (DSB). The present study demonstrates that the abundant near zero-eV (0.5 eV) electrons, created by ionizing radiation during radiotherapy, induce DSB in supercoiled plasmid DNA modified by platinum-containing anticancer drugs (Pt drugs), but not in unmodified DNA. They do so more efficiently than other types of radiation, including soft X-rays and 10 eV electrons. The formation of DSB by 0.5 eV electrons is found to be a single-hit process. These findings reveal insights into the radiosensitization mechanism of Pt drugs that can have implications for the development of optimal clinical protocols for platinum-based CCRT and the deployment of in situ sources of subexcitation-energy electrons (e.g., Auger electron-emitting radionuclides) to efficiently enhance DSB formation in DNA modified by Pt drugs in malignant cells. PMID:24376113

  13. A Radiosonde Using a Humidity Sensor Array with a Platinum Resistance Heater and Multi-Sensor Data Fusion

    PubMed Central

    Shi, Yunbo; Luo, Yi; Zhao, Wenjie; Shang, Chunxue; Wang, Yadong; Chen, Yinsheng

    2013-01-01

    This paper describes the design and implementation of a radiosonde which can measure the meteorological temperature, humidity, pressure, and other atmospheric data. The system is composed of a CPU, microwave module, temperature sensor, pressure sensor and humidity sensor array. In order to effectively solve the humidity sensor condensation problem due to the low temperatures in the high altitude environment, a capacitive humidity sensor including four humidity sensors to collect meteorological humidity and a platinum resistance heater was developed using micro-electro-mechanical-system (MEMS) technology. A platinum resistance wire with 99.999% purity and 0.023 mm in diameter was used to obtain the meteorological temperature. A multi-sensor data fusion technique was applied to process the atmospheric data. Static and dynamic experimental results show that the designed humidity sensor with platinum resistance heater can effectively tackle the sensor condensation problem, shorten response times and enhance sensitivity. The humidity sensor array can improve measurement accuracy and obtain a reliable initial meteorological humidity data, while the multi-sensor data fusion technique eliminates the uncertainty in the measurement. The radiosonde can accurately reflect the meteorological changes. PMID:23857263

  14. Performance and durability of electrodes with platinum catalysts in polymer electrolyte cells prepared by ultrasonic spray deposition

    NASA Astrophysics Data System (ADS)

    Rigdon, William A.

    The development of stable platinum electrocatalysts for durable electrode performance has been a goal of this research. Cost of these materials is a major barrier to commercialization of technology such as polymer electrolyte fuel cells. Catalysts need to be supported on inexpensive materials that use a minimal amount of platinum while maintaining a high activity over the life of the device. Carbon support corrosion is the origin of many problems plaguing electrocatalyst longevity. Instead of replacing carbon with a ceramic or another single phase material, this dissertation has explored a composite consisting of both carbon nanotubes and titania to support platinum catalysts. Graphitized carbons and stable metal oxides have become a popular material selection for catalyst supports in many recent publications, but their design lacks a fundamental understanding. High performance and durability have been reported, although successful application in working electrodes is necessary to validate these advantages. Titania and carbon nanotube supports for platinum were able to better preserve catalyst performance than a control without titania in the cathode. Choice of a niobium donor dopant in titania was used in an approach to modify the structure and electronic properties of the metal oxide phase when integrated into the anode. When included into electrocatalysts, semiconductor oxides promote bifunctional mechanisms through junctions formed with the catalyst. Strong metal-support interactions enhanced catalyst bonding characteristics extended from the support. An ultrasonic spray deposition process was used to prepare membrane electrode assemblies from the synthesized electrocatalysts. A synergy between both performance and durability of electrodes can be realized by design of better composite supports used in fuel cells and potentially other related electrochemical devices.

  15. Quantitative bioimaging of platinum group elements in tumor spheroids.

    PubMed

    Niehoff, Ann-Christin; Grünebaum, Jonas; Moosmann, Aline; Mulac, Dennis; Söbbing, Judith; Niehaus, Rebecca; Buchholz, Rebecca; Kröger, Sabrina; Wiehe, Arno; Wagner, Sylvia; Sperling, Michael; von Briesen, Hagen; Langer, Klaus; Karst, Uwe

    2016-09-28

    Limited drug penetration into tumor tissue is a significant factor to the effectiveness of cancer therapy. Tumor spheroids, a 3D cell culture model system, can be used to study drug penetration for pharmaceutical development. In this study, a method for quantitative bioimaging of platinum group elements by laser ablation (LA) coupled to inductively coupled plasma mass spectrometry (ICP-MS) is presented. Different matrix-matched standards were used to develop a quantitative LA-ICP-MS method with high spatial resolution. To investigate drug penetration, tumor spheroids were incubated with platinum complexes (Pt(II)acetylacetonate, cisplatin) and the palladium tagged photosensitizer 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (mTHPP). Distribution and accumulation of the pharmaceuticals were determined with the developed method. PMID:27619092

  16. Nanostructured gold and platinum electrodes on silicon structures for biosensing

    NASA Astrophysics Data System (ADS)

    Ogurtsov, V. I.; Sheehan, M. M.

    2005-01-01

    Gold and platinum metal electrodes on Si/SiO2 having undergone anisotropic potassium hydroxide (KOH) etch treatment are considered. This treatment etches at different rates and directions in the material resulting in creation of numerous pyramid shaped holes in the silicon substrate. This surface is used to make metal electrodes with increased electrode efficiency. The electrodes can serve as the sensors or as the sensor substrates (for surface polymer modification) and because both gold and platinum are inert they have applications for food safety biosensing. Wine, an economically significant food product, was chosen as a matrix, and impedance spectroscopy (EIS) was selected as a method of investigation of electrode behaviour. Based on results of EIS, different complexity equivalent circuits were determined by applying fitting mean square root optimisation of sensor complex impedance measurements.

  17. SNMS investigations of platinum-doped nanogranular tin dioxide layers

    NASA Astrophysics Data System (ADS)

    Schneider, T.; Sommer, M.; Goschnick, J.

    2005-09-01

    Thin platinum-doped nanogranular SnO 2 layers are examined because of its high gas sensitivity and fast gas response to be applied in gas sensor microarrays. The nanogranular metal oxide layers were prepared from a colloidal dispersion using spin coating on silicon substrates. Field emission scanning electron microscopy (FE-SEM) investigations showed quite homogeneous layers of 20 nm particles, containing a few holes of some micron width, probably due to bubbles introduced into the layer during wet deposition. Depth resolved analysis with secondary neutral mass spectrometry (SNMS) was employed to characterize the elemental content and depth distribution of the 20 nm particle layers. A platinum content of approx. 1 at.%, homogeneously spread throughout the particles was found, as well as carbon and chlorine residues of a few atomic percent enriched at the surface of the particles.

  18. Platinum(IV)-chlorotoxin (CTX) conjugates for targeting cancer cells.

    PubMed

    Graf, Nora; Mokhtari, Tara E; Papayannopoulos, Ioannis A; Lippard, Stephen J

    2012-05-01

    Cisplatin is one of the most widely used anticancer drugs. Its side effects, however, have motivated researchers to search for equally effective analogs that are better tolerated. Selectively targeting cancer tissue is one promising strategy. For this purpose, a platinum(IV) complex was conjugated to the cancer-targeting peptide chlorotoxin (CTX, TM601) in order to deliver cisplatin selectively to cancer cells. The 1:1 Pt-CTX conjugate was characterized by mass spectrometry and gel electrophoresis. Like most platinum(IV) derivatives, the cytotoxicity of the conjugate was lower in cell culture than that of cisplatin, but greater than those of its Pt(IV) precursor and CTX in several cancer cell lines. PMID:22465700

  19. Extremely fast hydrogen absorption/desorption through platinum overlayers

    NASA Astrophysics Data System (ADS)

    Połczyński, Piotr; Jurczakowski, Rafał

    2016-02-01

    The hydrogen electrosorption in thin palladium films (50-1000 nm) was investigated at palladium electrodes covered with platinum overlayers. The results for this model system show that the rates of the hydrogen sorption/desorption are orders of magnitude higher for platinized samples with respect to pure palladium. The highest absorption kinetics have been observed for Pd electrodes fully covered with 1-3 platinum monolayers. By means of electrochemical impedance spectroscopy (EIS) we have shown that the process is diffusion limited at platinized Pd layers. Diffusion coefficient, DH, determined in EIS, is two orders of magnitude higher than that previously reported for thin palladium films and approaches DH for bulk palladium. The system stability after hydrogen absorption was assessed and the sorption mechanism was discussed. Surprisingly high durability of the platinized palladium enables its use in a variety of applications where fast and selective response in the presence of hydrogen is required.

  20. International strategic minerals inventory summary report: platinum-group metals

    USGS Publications Warehouse

    Sutphin, David M.; Page, Norman J

    1986-01-01

    Major world resources of platinum-group metals are described in this summary report of information in the International Strategic Minerals Inventory {ISMI}. ISMI is a cooperative data-collection effort of earth-science and mineral-resource agencies in Australia, Canada, the Federal Republic of Germany, the Republic of South Africa, and the United States of America. This report, designed to be of benefit to policy analysts, contains two parts. Part I presents an overview of the resources and potential supply of platinum-group metals on the basis of inventory information. Part II contains tables of some of the geologic information and mineral-resource and production data that were collected by ISMI participants.

  1. Joining lead wires to thin platinum alloy films

    NASA Technical Reports Server (NTRS)

    Przybyszewski, J. S.; Claing, R. G. (Inventor)

    1983-01-01

    A two step process of joining a lead wire to .000002 m thick platinum alloy film which rests upon an equally thin alumina insulating layer which is adhered to a metal substrate is described. Typically the platinum alloy film forms part of a thermocouple for measuring the surface temperature of a gas turbine airfoil. In the first step the lead wire is deformed 30 to 60% at room temperature while the characteristic one million ohm resistance of the alumina insulating layer is monitored for degradation. In the second step the cold pressed assembly is heated at 865 to 1025 C for 4 to 75 hr in air. During the heating step any degradation of insulating layer resistance may be reversed, provided the resistance was not decreased below 100 ohm in the cold pressing.

  2. Platinum nanoparticle decorated silicon nanowires for efficient solar energy conversion.

    PubMed

    Peng, Kui-Qing; Wang, Xin; Wu, Xiao-Ling; Lee, Shuit-Tong

    2009-11-01

    High-density aligned n-type silicon nanowire (SiNW) arrays decorated with discrete 5-10 nm platinum nanoparticles (PtNPs) have been fabricated by aqueous electroless Si etching followed by an electroless platinum deposition process. Coating of PtNPs on SiNW sidewalls yielded a substantial enhancement in photoconversion efficiency and an apparent energy conversion efficiency of up to 8.14% for the PtNP-decorated SiNW-based photoelectrochemical solar cell using a liquid electrolyte containing Br(-)/Br(2) redox couple. The results demonstrate PtNP-decorated SiNWs to be a promising hybrid system for solar energy conversion. PMID:19807069

  3. Pump apparatus including deconsolidator

    DOEpatents

    Sonwane, Chandrashekhar; Saunders, Timothy; Fitzsimmons, Mark Andrew

    2014-10-07

    A pump apparatus includes a particulate pump that defines a passage that extends from an inlet to an outlet. A duct is in flow communication with the outlet. The duct includes a deconsolidator configured to fragment particle agglomerates received from the passage.

  4. High low-temperature CO oxidation activity of platinum oxide prepared by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Johánek, V.; Václavů, M.; Matolínová, I.; Khalakhan, I.; Haviar, S.; Matolín, V.

    2015-08-01

    CO oxidation on platinum oxide deposited by magnetron sputtering on flat (Si) and highly porous (multi-walled carbon nanotubes, MWCNT) substrates were examined using X-ray photoelectron spectroscopy, scanning tunneling microscopy, temperature-programmed desorption and temperature-programmed reaction in both UHV and ambient pressure conditions. Platinum in the freshly deposited thin film is present entirely in the 4+ oxidation state. The intrinsic CO oxidation capability of such catalyst proved to be significantly higher under approx. 480 K than that of pure platinum, presumably due to the interplay between metallic and cationic platinum entities, and the reaction yield can be further enhanced by increasing effective surface area when MWCNT is used as a support. The thermo-chemical stability of the platinum oxide, however, has its limitations as the thin film can be gradually thermally reduced to metallic platinum (with small residuum of stable Pt2+ species) and this process is further facilitated in the presence of reducing CO atmosphere.

  5. Web Search Agents: "One-Stop Shopping" for Researchers.

    ERIC Educational Resources Information Center

    Perez, Ernest

    2002-01-01

    Explains Web search agents as tools that apply intelligent agent software technology for the purpose of automating, improving, and speeding up online search operations. Topics include intelligent desktop agents; search agent marketplace; comparing Web search agents; subjective evaluations; and use by researchers. (LRW)

  6. Agent planning in AgScala

    NASA Astrophysics Data System (ADS)

    Tošić, Saša; Mitrović, Dejan; Ivanović, Mirjana

    2013-10-01

    Agent-oriented programming languages are designed to simplify the development of software agents, especially those that exhibit complex, intelligent behavior. This paper presents recent improvements of AgScala, an agent-oriented programming language based on Scala. AgScala includes declarative constructs for managing beliefs, actions and goals of intelligent agents. Combined with object-oriented and functional programming paradigms offered by Scala, it aims to be an efficient framework for developing both purely reactive, and more complex, deliberate agents. Instead of the Prolog back-end used initially, the new version of AgScala relies on Agent Planning Package, a more advanced system for automated planning and reasoning.

  7. Radiosensitization of EMT6 cells by four platinum complexes

    SciTech Connect

    Teicher, B.A.; Rockwell, S.; Lee, J.B.

    1985-05-01

    The compounds described here are dichloro complexes of bivalent platinum with one or two potentially radiosensitizing ligands. The radiosensitization of oxygenated and hypoxic exponentially growing EMT6 cells in vitro was measured. The dose modifying factors obtained with 200 ..mu..M and 400 ..mu..M trans-bis(2-nitroimidazole)dichloroplatinum II (NIPt) in hypoxic cells were 1.5 and 2.1, respectively. For trans-bis(2-amino-5-nitrothiazole)dichloroplatinum II (Plant) under the same conditions, the dose modifying factor was 1.5 at 200 ..mu..M and 1.8 at 400 ..mu..M. Neither compound sensitized oxygenated cells when tested similar protocols. Unlike the trans complexes (1,2-diamino-4-nitrobenzene)dichloroplatinum II (Plato) was cytotoxic toward the hypoxic cells in the absence of X rays. The time course of cytotoxicity for 100 ..mu..M Plato in exponentially growing cells showed rapid killing of hypoxic cells, and much less toxicity toward oxygenated cells. In radiosensitization studies, dose modifying factors of 1.6 and 2.0 were found with 200 ..mu..M and 400 ..mu..M Plato in hypoxic cells. The compound did not sensitize aerobic cells. The well-known platinum complex cis-dipyridinedichloroplatinum II (PyPt) represents a cis-platinum heterocyclic aromatic complex that does not have a nitro-functionality. The dose modifying factor obtained with 400 ..mu..M PyPt in hypoxic cells was 1.7. On a molar basis, the nitro-functional platinum complexes appear to be more effective as hypoxic cell radiosensitizers than the corresponding free ligands.

  8. Platinum(II) complexes as spectroscopic probes for biomolecules

    SciTech Connect

    Ratilla, E.

    1990-09-21

    The use of platinum(II) complexes as tags and probes for biomolecules is indeed advantageous for their reactivities can be selective for certain purposes through an interplay of mild reaction conditions and of the ligands bound to the platinum. The use of {sup 195}Pt NMR as a method of detecting platinum and its interactions with biomolecules was carried out with the simplest model of platinum(II) tagging to proteins. Variable-temperature {sup 195}Pt NMR spectroscopy proved useful in studying the stereodynamics of complex thioethers like methionine. The complex, Pt(trpy)Cl{sup +}, with its chromophore has a greater potential for probing proteins. It is a noninvasive and selective tag for histidine and cysteine residues on the surface of cytochrome c at pH 5. The protein derivatives obtained are separable, and the tags are easily quantitated and differentiated through the metal-to-ligand charge transfer bands which are sensitive to the environment of the tag. Increasing the pH to 7.0 led to the modification by Pt(trpy)Cl{sup +}of Arg 91 in cytochrome c. Further studies with guanidine-containing ligands as models for arginine modification by Pt(trpy)Cl{sup +} showed that guanidine can act as a terminal ligand and as a bridging ligand. Owing to the potential utility of Pt(trpy)L{sup n+} as electron dense probes of nucleic acid structure, interactions of this bis-Pt(trpy){sup 2+} complex with nucleic acids was evaluated. Indeed, the complex interacts non-covalently with nucleic acids. Its interactions with DNA are not exactly the same as those of its precedents. Most striking is its ability to form highly immobile bands of DNA upon gel electrophoresis. 232 refs.

  9. Double-Stranded Water on Stepped Platinum Surfaces

    NASA Astrophysics Data System (ADS)

    Kolb, Manuel J.; Farber, Rachael G.; Derouin, Jonathan; Badan, Cansin; Calle-Vallejo, Federico; Juurlink, Ludo B. F.; Killelea, Daniel R.; Koper, Marc T. M.

    2016-04-01

    The interaction of platinum with water plays a key role in (electro)catalysis. Herein, we describe a combined theoretical and experimental study that resolves the preferred adsorption structure of water wetting the Pt(111)-step type with adjacent (111) terraces. Double stranded lines wet the step edge forming water tetragons with dissimilar hydrogen bonds within and between the lines. Our results qualitatively explain experimental observations of water desorption and impact our thinking of solvation at the Pt electrochemical interface.

  10. Photochemistry and charge transfer chemistry of the platinum group elements

    SciTech Connect

    Eisenberg, R.

    1991-12-01

    Significant progress has been made on the photochemistry and photophysics of platinum group element dithiolate complexes. The specific systems under investigation are square planar complexes of Pt(II) containing a dithiolate chelate and two other donor groups to complete the coordination sphere. The donor groups may be amines, imines, phosphines, phosphites or olefins, and they can be either monodentate or joined together as part of a chelate ring.

  11. Nucleolar damage correlates with neurotoxicity induced by different platinum drugs

    PubMed Central

    McKeage, M J; Hsu, T; Screnci, D; Haddad, G; Baguley, B C

    2001-01-01

    Platinum-based drugs are very useful in cancer therapy but are associated with neurotoxicity in the clinic. To investigate the mechanism of neurotoxicity, dorsal root ganglia of rats treated with various platinum drugs were studied. Cell body, nuclear and nucleolar dimensions of dorsal root ganglia sensory nerve cells were measured to determine morphological toxicity. Sensory nerve conduction velocity was measured to determine functional toxicity. After a single dose of oxaliplatin (10 mg kg−1), no significant change in nuclear and cell body diameter was seen but decreased nucleolar size was apparent within a few hours of treatment. Changes in nucleolar size were maximal at 24 hours, recovered very slowly and showed a non-linear dependence on oxaliplatin dose (r2= 0.99). Functional toxicity was delayed in onset until 14 days after a single dose of oxaliplatin but eventually recovered 3 months after treatment. Multiple doses of cisplatin, carboplatin, oxaliplatin, R, R -ormaplatin and S, S -ormaplatin were also associated with time-dependent reduction in nucleolar size. A linear correlation was obtained between the rate of change in nucleolar size during multiple dose treatment with the series of platinum drugs and the time taken for the development of altered sensory nerve conduction velocity (r2= 0.86;P< 0.024). Damage to the nucleolus of ganglionic sensory neurons is therefore linked to the neurotoxicity of platinum-based drugs, possibly through mechanisms resulting in the inhibition of rRNA synthesis. © 2001 Cancer Research Campaign  http://www.bjcancer.com PMID:11710838

  12. Prospective cohort study to evaluate the efficacy of taxane plus platinum and CPT-11plus platinum regimes and to identify prognostic risk factors in cervical cancer patients

    PubMed Central

    Huang, Kecheng; Li, Xiong; Yang, Ru; Shen, Jian; Chen, Zhilan; Qin, Xiaomin; Wang, Shaoshuai; Jia, Yao; Tang, Fangxu; Zhou, Hang; Sun, Haiying; Zhou, Jin; Guo, Lili; Wang, Lin; Qiao, Long; Xiong, Jiaqiang; Wang, Congyi; Ma, Ding; Li, Shuang; Hu, Ting; Wang, Shixuan

    2015-01-01

    Objective: This study was designed to evaluate the response, toxicity and survival of taxanes plus platinum (TP) and CPT-11plus platinum (CP) as neoadjuvant chemotherapies with previously untreated cervical cancer, and to identify prognostic risk factors in these patients. Methods: A cohort study was performed to evaluate the result of TP and CP regimes in the treatment of cervical cancer patients. Results: The study included 567 patients with locally advanced cervical cancer (LACC) staged as FIGO IB-IIB in our clinical departments. Clinical response was found in 76.1% and 78% of patients in the TP and CP arms, respectively, and no treatment-related deaths were reported. During the follow-up period, disease-free survival (DFS) and overall survival (OS) for the TP and CP arms were not different (P = 0.384 for DFS, P = 0.800 for OS). The CP regime showed higher survival rate for endophytic growth style (P = 0.013 for DFS, P = 0.027 for OS). The CP regime also showed higher DFS and OS for G2 tumor (P = 0.027 for DFS, P = 0.032 for OS). In multivariate cox’s proportional hazards regression model, the average death rates were much greater in the non-responder group (HR, 2.68), in the older (> 44 years) group (HR, 2.51), and in the FIGO stage II b patients (HR, 2.84). Conclusions: The CP regime showed higher survival rate for endophytic growth style or G2 tumor. Clinical response, age and FIGO stage were independent prognostic risk factors in this study for both DFS and OS. PMID:26628986

  13. Platinum-induced structural collapse in layered oxide polycrystalline films

    SciTech Connect

    Wang, Jianlin; Liu, Changhui; Huang, Haoliang; Fu, Zhengping; Peng, Ranran E-mail: yllu@ustc.edu.cn; Zhai, Xiaofang; Lu, Yalin E-mail: yllu@ustc.edu.cn

    2015-03-30

    Effect of a platinum bottom electrode on the SrBi{sub 5}Fe{sub 1−x}Co{sub x}Ti{sub 4}O{sub 18} layered oxide polycrystalline films was systematically studied. The doped cobalt ions react with the platinum to form a secondary phase of PtCoO{sub 2}, which has a typical Delafossite structure with a weak antiferromagnetism and an exceptionally high in-plane electrical conductivity. Formation of PtCoO{sub 2} at the interface partially consumes the cobalt dopant and leads to the structural collapsing from 5 to 4 layers, which was confirmed by X-ray diffraction and high resolution transmission electron microscopy measurements. Considering the weak magnetic contribution from PtCoO{sub 2}, the observed ferromagnetism should be intrinsic of the Aurivillius compounds. Ferroelectric properties were also indicated by the piezoresponse force microscopy. In this work, the platinum induced secondary phase at the interface was observed, which has a strong impact on Aurivillius structural configuration and thus the ferromagnetic and ferroelectric properties.

  14. Platinum redispersion on metal oxides in low temperature fuel cells.

    PubMed

    Tripković, Vladimir; Cerri, Isotta; Nagami, Tetsuo; Bligaard, Thomas; Rossmeisl, Jan

    2013-03-01

    We have analyzed the aptitude of several metal oxide supports (TiO(2), SnO(2), NbO(2), ZrO(2), SiO(2), Ta(2)O(5) and Nb(2)O(5)) to redisperse platinum under electrochemical conditions pertinent to the Proton Exchange Membrane Fuel Cell (PEMFC) cathode. The redispersion on oxide supports in air has been studied in detail; however, due to different operating conditions it is not straightforward to link the chemical and the electrochemical environment. The largest differences reflect in (1) the oxidation state of the surface (the oxygen species coverage), (2) temperature and (3) the possibility of platinum dissolution at high potentials and the interference of redispersion with normal working potential of the PEMFC cathode. We have calculated the PtO(x) (x = 0, 1, 2) adsorption energies on different metal oxides' surface terminations as well as inside the metal oxides' bulk, and we have concluded that NbO(2) might be a good support for platinum redispersion at PEMFC cathodes. PMID:23358311

  15. Heteroleptic Complexes of Cyclometalated Platinum with Triarylformazanate Ligands.

    PubMed

    Kabir, Evanta; Wu, Chia-Hua; Wu, Judy I-Chia; Teets, Thomas S

    2016-01-19

    Formazanates are a ligand class featuring a 1,2,4,5-tetraazapentadienyl core, with variable substitution at the 1, 3, and 5 positions. Here we describe a set of four heteroleptic cylcometalated platinum complexes containing triarylformazanate ligands. The complexes are prepared by metathesis reactions of chloro-bridged dimers [Pt(C∧N)(μ-Cl)]2 (C∧N = 2-phenylpyridine or 2-(2,4-difluorophenyl)pyridine) with triarylformazans in the presence of base. X-ray diffraction studies reveal the molecular structures of three such complexes. Cyclic voltammograms and UV-vis absorption spectra of the complexes show features characteristic of both the cyclometalated platinum fragment and the formazanate, with the latter giving rise to two reversible one-electron reductions in the CV and an intense visible π → π* absorption which is red-shifted by >100 nm relative to the free formazan. The electronic structures and redox properties of the complexes were further investigated by UV-vis spectroelectrochemistry and density functional theory calculations. All of the experimental and theoretical work points to a frontier molecular orbital manifold where the formazanate π and π* orbitals are substantially mixed with d-orbitals derived from the platinum center. PMID:26702999

  16. Platinum-induced structural collapse in layered oxide polycrystalline films

    NASA Astrophysics Data System (ADS)

    Wang, Jianlin; Huang, Haoliang; Liu, Changhui; Fu, Zhengping; Zhai, Xiaofang; Peng, Ranran; Lu, Yalin

    2015-03-01

    Effect of a platinum bottom electrode on the SrBi5Fe1-xCoxTi4O18 layered oxide polycrystalline films was systematically studied. The doped cobalt ions react with the platinum to form a secondary phase of PtCoO2, which has a typical Delafossite structure with a weak antiferromagnetism and an exceptionally high in-plane electrical conductivity. Formation of PtCoO2 at the interface partially consumes the cobalt dopant and leads to the structural collapsing from 5 to 4 layers, which was confirmed by X-ray diffraction and high resolution transmission electron microscopy measurements. Considering the weak magnetic contribution from PtCoO2, the observed ferromagnetism should be intrinsic of the Aurivillius compounds. Ferroelectric properties were also indicated by the piezoresponse force microscopy. In this work, the platinum induced secondary phase at the interface was observed, which has a strong impact on Aurivillius structural configuration and thus the ferromagnetic and ferroelectric properties.

  17. Reduced hydrogen embrittlement susceptibility in platinum implanted high strength steel

    NASA Astrophysics Data System (ADS)

    Cowie, J. G.; Lowder, L. J.; Culbertson, R. J.; Kosik, W. E.; Brown, R.

    1991-07-01

    High strength steels suffer from a high susceptibility to hydrogen embrittlement in a corrosive atmosphere, a factor which limits their usefulness. A good catalyst, such as platinum, present on the surface of the steel may lead to a low value of hydrogen overvoltage, thereby reducing the accumulation and subsequent diffusion of atomic hydrogen into the metal. In the present study, platinum was implanted into high strength electroslag remelted (ESR) 4340 steel specimens to a dose of 10 16 atoms/cm 2. Both Pt-implanted and unimplanted specimens were rate charged with hydrogen. The relative concentration of diffusible hydrogen was determined using an electrochemical measurement device known as a Barnacle Electrode. The specimens implanted with platinum exhibited less diffusible hydrogen than the unimplanted steel. Slow strain rate notched-tensile tests, in an aqueous solution of 3.5 wt.% NaCI, were performed in order to evaluate the effect of hydrogen on strength and ductility. The Pt-implanted specimens were able to sustain significantly higher loads before fracture than their unimplanted counterparts. Scanning electron microscopy (SEM) verified the presence of brittle cracking typical of hydrogen embrittlement type failures. Degradation of mechanical properties due to hydrogen embrittlement was thus significantly reduced. This suggested that both the electrochemical and catalytic properties of the Pt-implanted surface were responsible for the improvement in properties.

  18. In vitro free radical scavenging activity of platinum nanoparticles

    NASA Astrophysics Data System (ADS)

    Watanabe, Aki; Kajita, Masashi; Kim, Juewon; Kanayama, Atsuhiro; Takahashi, Kyoko; Mashino, Tadahiko; Miyamoto, Yusei

    2009-11-01

    A polyacrylic acid (PAA)-protected platinum nanoparticle species (PAA-Pt) was prepared by alcohol reduction of hexachloroplatinate. The PAA-Pt nanoparticles were well dispersed and homogeneous in size with an average diameter of 2.0 ± 0.4 nm (n = 200). We used electron spin resonance to quantify the residual peroxyl radical (\\mathrm {AOO}^{\\bullet } ) generated from 2,2-azobis (2-aminopropane) dihydrochloride (AAPH) by thermal decomposition in the presence of O2 and a spectrophotometric method to quantify the residual 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. PAA-Pt scavenged these two radicals in a dose-dependent manner. Platinum was the functional component. PAA-Pt reduced the rate of oxygen consumption required for linoleic acid peroxidation initiated by \\mathrm {AOO}^{\\bullet } generated from AAPH, indicating inhibition of the propagation of linolate peroxidation. A thiobarbituric acid test also revealed dose-dependent inhibition of the linolate peroxidation by PAA-Pt. Fifty micromolar platinum, as PAA-Pt, completely quenched 250 µM DPPH radical for 5 min. Even when twice diluted in half, the PAA-Pt still quenched 100% of the 250 µM DPPH radical. The scavenging activity of PAA-Pt is durable. These observations suggest that PAA-Pt is an efficient scavenger of free radicals.

  19. Optical modulator including grapene

    DOEpatents

    Liu, Ming; Yin, Xiaobo; Zhang, Xiang

    2016-06-07

    The present invention provides for a one or more layer graphene optical modulator. In a first exemplary embodiment the optical modulator includes an optical waveguide, a nanoscale oxide spacer adjacent to a working region of the waveguide, and a monolayer graphene sheet adjacent to the spacer. In a second exemplary embodiment, the optical modulator includes at least one pair of active media, where the pair includes an oxide spacer, a first monolayer graphene sheet adjacent to a first side of the spacer, and a second monolayer graphene sheet adjacent to a second side of the spacer, and at least one optical waveguide adjacent to the pair.

  20. Electrocatalyst for oxygen reduction with reduced platinum oxidation and dissolution rates

    SciTech Connect

    Adzic, Radoslav; Zhang, Junliang; Vukmirovic, Miomir

    2012-11-13

    The invention relates to platinum-metal oxide composite particles and their use as electrocatalysts in oxygen-reducing cathodes and fuel cells. The invention particularly relates to methods for preventing the oxidation of the platinum electrocatalyst in the cathodes of fuel cells by use of these platinum-metal oxide composite particles. The invention additionally relates to methods for producing electrical energy by supplying such a fuel cell with an oxidant, such as oxygen, and a fuel source, such as hydrogen.

  1. Cisplatin based chemotherapy in testicular cancer patients: long term platinum excretion and clinical effects.

    PubMed

    Hohnloser, J H; Schierl, R; Hasford, B; Emmerich, B

    1996-09-20

    Patients with advanced testicular cancer (TC) have a very good long-term prognosis owing to cisplatin-based polychemotherapy. Platinum is believed to be excreted at a rapid rate via urine within weeks after chemotherapy. As a new, highly sensitive method has become available detecting even natural background platinum levels in body fluids, this study was set up to analyze urinary and serum platinum levels in long-term survivors of testicular neoplasm after cisplatin based polychemotherapy and to correlate clinical data with urinary and serum platinum levels. Urinary platinum concentrations were measured in 64 healthy controls (C) and 22 male patients (TC) 150 to 3022 days after the last application of i.v. cisplatin using voltammetry after UV-photolysis. In the latter group (TC), serum platinum levels were measured as well. Clinical data were analysed as to long-term organ toxicity. Mean urinary platinum levels were 2700 times higher in the patient group (TC) than natural background noise (p < 0.0001). There was a decline of urinary and serum platinum levels over time, being significantly above normal even 8 years after cisplatin exposure. The only significant variables related to the urine platinum concentration were a) the interval between the last i.v. cisplatin application and time of study and b) the total dose given. Not significant were the number of chemotherapy cycles, pre-therapy renal disease, patient age, tumour resection before/after chemotherapy, site of pre/post therapy resection, clinical staging, histological subtypes or tumour markers. Post-therapy renal disease or peripheral nerve damage were not significantly associated with urinary platinum levels. Our data indicate that even 8 years after cisplatin based chemotherapy 500 times elevated urinary and serum platinum levels can be measured in testicular cancer patients. No organ toxicity related to long-term platinum excretion could be detected. This may be due to our small sample size. PMID

  2. Electrocatalyst for oxygen reduction with reduced platinum oxidation and dissolution rates

    DOEpatents

    Adzic, Radoslav; Zhang, Junliang; Vukmirovic, Miomir

    2011-11-22

    The invention relates to platinum-metal oxide composite particles and their use as electrocatalysts in oxygen-reducing cathodes and fuel cells. The invention particularly relates to methods for preventing the oxidation of the platinum electrocatalyst in the cathodes of fuel cells by use of these platinum-metal oxide composite particles. The invention additionally relates to methods for producing electrical energy by supplying such a fuel cell with an oxidant, such as oxygen, and a fuel source, such as hydrogen.

  3. Platinum-group element resources in podiform chromitites from California and Oregon.

    USGS Publications Warehouse

    Page, N.J.; Singer, D.A.; Moring, B.C.; Carlson, C.A.; McDade, J.M.; Wilson, S.A.

    1986-01-01

    Assays of Pt, Pd, Rh and Ir from approx 280 podiform chromite deposits in Palaeozoic and Mesozoic ophiolites are statistically analysed to estimate their possible by-product value from mining the chromite. The platinum-group elements occur in discrete platinum-group minerals, and in solid solution in Cu-Ni-Fe sulphides. Low grades and small amounts of total platinum-group elements in podiform chromite deposits imply a small resource. -G.J.N.

  4. Optimum Platinum Loading In Pt/SnO2 CO-Oxidizing Catalysts

    NASA Technical Reports Server (NTRS)

    Schryer, David R.; Upchurch, Billy T.; Davis, Patricia P.; Brown, Kenneth G.; Schryer, Jacqueline

    1991-01-01

    Platinum on tin oxide (Pt/SnO2) good catalyst for oxidation of carbon monoxide at or near room temperature. Catalytic activity peaks at about 17 weight percent Pt. Catalysts with platinum loadings as high as 46 percent fabricated by technique developed at Langley Research Center. Work conducted to determine optimum platinum loading for this type of catalyst. Major application is removal of unwanted CO and O2 in CO2 lasers.

  5. Hydroxypyridonate chelating agents and synthesis thereof

    DOEpatents

    Raymond, K.N.; Scarrow, R.C.; White, D.L.

    1985-11-12

    Chelating agents having 1-hydroxy-2-pyridinone (HOPO) and related moieties incorporated within their structures, including polydentate HOPO-substituted polyamines such as spermidine and spermine, and HOPO-substituted desferrioxamine. The chelating agents are useful in selectively removing certain cations from solution, and are particularly useful as ferric ion and actinide chelators. Novel syntheses of the chelating agents are provided. 4 tabs.

  6. Platinum and Gold Mining in South Africa: The Context of the Marikana Massacre.

    PubMed

    Cairncross, Eugene; Kisting, Sophia

    2016-02-01

    Mining is a source of extraordinary wealth, but its benefits often do not accrue to the workers and communities most involved. This paper presents two case studies of mining in South Africa to reflect on the history and legacy of mining both through observation and through the voices of affected communities. Interviews and observations on field visits to the platinum and gold mining areas of South Africa in the immediate aftermath of the Marikana massacre highlight this legacy--including vast quantities of tailings dumps and waste rock, lakes of polluted water and a devastated physical and social environment, high unemployment, high rates of occupational injury and disease including silicosis with co-morbidities, absent social security, and disrupted rural and agricultural communities. Exploitative conditions of work and the externalization of the health and environmental costs of mining will require international solidarity, robust independent trade unions, and a commitment to human rights. PMID:26721787

  7. Preparing Change Agents for Change Agent Roles.

    ERIC Educational Resources Information Center

    Sedlacek, James R.

    Seventy-seven Spanish- and Portuguese-speaking agricultural change agents from developing Central and South American countries responded to a questionnaire which sought perceptions of the roles in which the change agents felt they were involved and the roles for which they felt they were being trained. The agents were participating in training…

  8. A new platinum complex with tryptophan: Synthesis, structural characterization, DFT studies and biological assays in vitro over human tumorigenic cells

    NASA Astrophysics Data System (ADS)

    Carvalho, Marcos A.; Shishido, Silvia M.; Souza, Bárbara C.; de Paiva, Raphael E. F.; Gomes, Alexandre F.; Gozzo, Fábio C.; Formiga, André L. B.; Corbi, Pedro P.

    2014-03-01

    A new platinum(II) complex with the amino acid L-tryptophan (trp), named Pt-trp, was synthesized and characterized. Elemental, thermogravimetric and ESI-QTOF mass spectrometric analyses led to the composition [Pt(C11H11N2O2)2]ṡ6H2O. Infrared spectroscopic data indicate the coordination of trp to Pt(II) through the oxygen of the carboxylate group and also through the nitrogen atom of the amino group. The 13C CP/MAS NMR spectroscopic data confirm coordination through the oxygen atom of the carboxylate group, while the 15N CP/MAS NMR data confirm coordination of the nitrogen of the NH2 group to the metal. Density functional theory (DFT) studies were applied to evaluate the cis and trans coordination modes of trp to platinum(II). The trans isomer was shown to be energetically more stable than the cis one. The Pt-trp complex was evaluated as a cytotoxic agent against SK-Mel 103 (human melanoma) and Panc-1 (human pancreatic carcinoma) cell lines. The complex was shown to be cytotoxic over the considered cells.

  9. Enzyme-mimetic effects of gold@platinum nanorods on the antioxidant activity of ascorbic acid

    NASA Astrophysics Data System (ADS)

    Zhou, Yu-Ting; He, Weiwei; Wamer, Wayne G.; Hu, Xiaona; Wu, Xiaochun; Lo, Y. Martin; Yin, Jun-Jie

    2013-01-01

    Au@Pt nanorods were prepared by growing platinum nanodots on gold nanorods. Using electron spin resonance (ESR), we determined that the mechanisms for oxidation of ascorbic acid (AA) by Au@Pt nanorods and ascorbic acid oxidase (AAO) were kinetically similar and yielded similar products. In addition we observed that Au@Pt nanorods were stable with respect to temperature and pH. Using UV-VIS spectroscopy, the apparent kinetics of enzyme-mimetic activity of Au@Pt nanorods were studied and compared with the activity of AAO. With the help of ESR, we found that Au@Pt nanorods did not scavenge hydroxyl radicals but inhibited the antioxidant ability of AA for scavenging hydroxyl radicals produced by photoirradiating solutions containing titanium dioxide and zinc oxide. Moreover, the Au@Pt nanorods reduced the ability of AA to scavenge DPPH radicals and superoxide radicals. These results demonstrate that Au@Pt nanorods can reduce the antioxidant activity of AA. Therefore, it is necessary to consider the effects of using Pt nanoparticles together with other reducing agents or antioxidants such as AA due to the oxidase-like property of Au@Pt nanorods.Au@Pt nanorods were prepared by growing platinum nanodots on gold nanorods. Using electron spin resonance (ESR), we determined that the mechanisms for oxidation of ascorbic acid (AA) by Au@Pt nanorods and ascorbic acid oxidase (AAO) were kinetically similar and yielded similar products. In addition we observed that Au@Pt nanorods were stable with respect to temperature and pH. Using UV-VIS spectroscopy, the apparent kinetics of enzyme-mimetic activity of Au@Pt nanorods were studied and compared with the activity of AAO. With the help of ESR, we found that Au@Pt nanorods did not scavenge hydroxyl radicals but inhibited the antioxidant ability of AA for scavenging hydroxyl radicals produced by photoirradiating solutions containing titanium dioxide and zinc oxide. Moreover, the Au@Pt nanorods reduced the ability of AA to scavenge

  10. Studies of glutathione transferase P1-1 bound to a platinum(IV)-based anticancer compound reveal the molecular basis of its activation.

    PubMed

    Parker, Lorien J; Italiano, Louis C; Morton, Craig J; Hancock, Nancy C; Ascher, David B; Aitken, Jade B; Harris, Hugh H; Campomanes, Pablo; Rothlisberger, Ursula; De Luca, Anastasia; Lo Bello, Mario; Ang, Wee Han; Dyson, Paul J; Parker, Michael W

    2011-07-01

    Platinum-based cancer drugs, such as cisplatin, are highly effective chemotherapeutic agents used extensively for the treatment of solid tumors. However, their effectiveness is limited by drug resistance, which, in some cancers, has been associated with an overexpression of pi class glutathione S-transferase (GST P1-1), an important enzyme in the mercapturic acid detoxification pathway. Ethacraplatin (EA-CPT), a trans-Pt(IV) carboxylate complex containing ethacrynate ligands, was designed as a platinum cancer metallodrug that could also target cytosolic GST enzymes. We previously reported that EA-CPT was an excellent inhibitor of GST activity in live mammalian cells compared to either cisplatin or ethacrynic acid. In order to understand the nature of the drug-protein interactions between EA-CPT and GST P1-1, and to obtain mechanistic insights at a molecular level, structural and biochemical investigations were carried out, supported by molecular modeling analysis using quantum mechanical/molecular mechanical methods. The results suggest that EA-CPT preferentially docks at the dimer interface at GST P1-1 and subsequent interaction with the enzyme resulted in docking of the ethacrynate ligands at both active sites (in the H-sites), with the Pt moiety remaining bound at the dimer interface. The activation of the inhibitor by its target enzyme and covalent binding accounts for the strong and irreversible inhibition of enzymatic activity by the platinum complex. PMID:21681839

  11. The preparation of well-defined dendrimer-encapsulated palladium and platinum nanoparticles and their catalytic evaluation in the oxidation of morin

    NASA Astrophysics Data System (ADS)

    Ncube, Phendukani; Hlabathe, Thaane; Meijboom, Reinout

    2015-12-01

    The preparation of dendrimer-encapsulated platinum (Pt-DENs) and palladium (Pd-DENs) nanoparticles using generation 6-hydroxyl-terminated poly(amidoamine) (PAMAM) dendrimers as a templating agent is described. These nanoparticles were characterized using UV-vis spectrophotometry, spectrofluorophotometry, Fourier transform infrared spectrometry (FTIR), and high resolution transmission electron microscopy (HRTEM). The UV-vis spectra of palladium and platinum dendrimer-encapsulated nanoparticles gave a clear proof that nanoparticles were formed. It was found from FTIR spectra that there are shifts of peaks from higher wave numbers to lower wave numbers after reduction with sodium borohydride and these confirm the encapsulation of nanoparticles inside the voids of the dendrimer. The particle diameters were found to be 1.4 ± 0.2 and 1.6 ± 0.2 nm in diameter for palladium and platinum respectively from HRTEM. These nanoparticles were evaluated as catalysts in the oxidation of morin by hydrogen peroxide. The kinetic data was modeled to the Langmuir-Hinshelwood equation. The model allows relating apparent rate constant to the total surface area (S) of the nanoparticle. The Langmuir-Hinshelwood model also allows a direct relationship between the kinetic constant (k) and Kmorin and KH2O2 . The Arrhenius and Eyring equations were used to determine thermodynamic parameters for the oxidation of morin.

  12. Antitumor effects of nano-bubble hydrogen-dissolved water are enhanced by coexistent platinum colloid and the combined hyperthermia with apoptosis-like cell death.

    PubMed

    Asada, Ryoko; Kageyama, Katsuhiro; Tanaka, Hiroshi; Matsui, Hisakazu; Kimura, Masatsugu; Saitoh, Yasukazu; Miwa, Nobuhiko

    2010-12-01

    In order to erase reactive oxygen species (ROS) related with the proliferation of tumor cells by reducing activity of hydrogen, we developed functional water containing nano-bubbles (diameters: <900 nm for 71%/population) hydrogen of 1.1-1.5 ppm (the theoretical maximum: 1.6 ppm) with a reducing ability (an oxidation-reduction potential -650 mV, normal water: +100-200 mV) using a microporous-filter hydrogen-jetting device. We showed that hydrogen water erased ROS indispensable for tumor cell growth by ESR/spin trap, the redox indicator CDCFH-DA assay, and was cytotoxic to Ehrlich ascites tumor cells as assessed by WST-8 assay, crystal violet dye stain and scanning electron microscopy, after 24-h or 48-h incubation sequent to warming at 37°C or 42°C. Hydrogen water supplemented with platinum colloid (0.3 ppm Pt in 4% polyvinylpyrrolidone) had more antitumor activity than hydrogen water alone, mineral water alone (15.6%), hydrogen water plus mineral water, or platinum colloid alone as observed by decreased cell numbers, cell shrinkage and pycnosis (nuclear condensation)/karyorrhexis (nuclear fragmentation) indicative of apoptosis, together with cell deformation and disappearance of microvilli on the membrane surface. These antitumor effects were promoted by combination with hyperthermia at 42°C. Thus, the nano-bubble hydrogen water with platinum colloid is potent as an anti-tumor agent. PMID:21042740

  13. Remote Agent Demonstration

    NASA Technical Reports Server (NTRS)

    Dorais, Gregory A.; Kurien, James; Rajan, Kanna

    1999-01-01

    We describe the computer demonstration of the Remote Agent Experiment (RAX). The Remote Agent is a high-level, model-based, autonomous control agent being validated on the NASA Deep Space 1 spacecraft.

  14. Platinum decorated Ru/C: Effects of decorated platinum on catalyst structure and performance for the methanol oxidation reaction

    NASA Astrophysics Data System (ADS)

    Gao, Haili; Liao, Shijun; Zeng, Jianhuang; Xie, Yichun

    Platinum decorated Ru/C catalysts are prepared by successive reduction of a platinum precursor on pre-formed Ru/C. Pt:Ru atomic ratios are varied from 0.13:1 to 0.81:1 to investigate the platinum decoration effects on the catalyst's structure and electrochemical performance towards the methanol oxidation reaction (MOR) at room temperature. The catalysts are extensively characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Ru@Pt/C catalysts show enhanced mass-normalized activity and specific activity for the MOR relative to Pt/C. For the anodic oxidation of methanol, the ratio of forward to reverse oxidation peak current R (I f/ I b) varies considerably: R decreases from 5.8 to 0.8 when the Pt:Ru ratio increases from 0.13:1 to 0.81:1. When the ratio of Pt:Ru is 0.42:1, R reaches 0.99 (close to that of Pt/C), and further increase of the Pt:Ru ratio leads to almost no decrease in R. Coincidentally, maximum mass-normalized activity is also obtained when Pt:Ru is 0.42:1.

  15. Tuning the DNA Conformational Perturbations Induced by Cytotoxic Platinum-Acridine Bisintercalators: Effect of Metal cis/trans Isomerism and DNA Threading Groups

    PubMed Central

    Choudhury, Jayati Roy; Guddneppanavar, Rajsekhar; Saluta, Gilda; Kucera, Gregory L.; Bierbach, Ulrich

    2009-01-01

    Four highly charged, water soluble platinum-acridine bisintercalating agents have been synthesized. Depending on the cis/trans isomerism of the metal and the nature of the acridine side chains, bisintercalation induces/stabilizes the classical Watson-Crick B-form or a non-B-form. Circular dichroism spectra and chemical footprinting experiments suggest that compound 4, the most active derivative in HL-60 cells, produces a structurally severely perturbed DNA with features of a Hoogsteen base-paired biopolymer. PMID:18457380

  16. Phase 1b safety study of farletuzumab, carboplatin and pegylated liposomal doxorubicin in patients with platinum-sensitive epithelial ovarian cancer☆,☆☆,★

    PubMed Central

    Kim, Kenneth H.; Jelovac, Danijela; Armstrong, Deborah K.; Schwartz, Benjamin; Weil, Susan C.; Schweizer, Charles; Alvarez, Ronald D.

    2016-01-01

    Objective Farletuzumab is a humanized monoclonal antibody that binds to folate receptor alpha, over-expressed in epithelial ovarian cancer (EOC) but largely absent in normal tissue. Previously, carboplatin plus pegylated liposomal doxorubicin showed superior progression-free survival and an improved therapeutic index compared with carboplatin/paclitaxel in relapsed platinum-sensitive EOC. This study assessed safety of farletuzumab/carboplatin/pegylated liposomal doxorubicin in women with platinum-sensitive recurrent EOC. Methods This multicenter, single-arm study enrolled patients with platinum-sensitive EOC in first or second relapse for treatment with weekly farletuzumab 2.5 mg/kg plus carboplatin AUC5–6 and pegylated liposomal doxorubicin 30 mg/m2 every 4 weeks for 6 cycles. Subsequently, maintenance with single-agent farletuzumab 2.5 mg/kg once weekly or farletuzumab 7.5 mg/kg once every three weeks continued until progression. The primary objective was to assess the safety of farletuzumab/carboplatin/pegylated liposomal doxorubicin. Results Fifteen patients received a median of 12.0 cycles (range, 3–26) of farletuzumab as combination therapy or maintenance, for a median of 45.0 weeks (range 9–95). Farletuzumab/carboplatin/pegylated liposomal doxorubicin was generally well tolerated, with no farletuzumab-related grades 3–4 adverse events. The most commonly reported adverse events were associated with combination chemotherapy: fatigue (73.3%), nausea (46.7%), and neutropenia (40%). Ten patients had grade ≥3 adverse events, most frequently neutropenia and fatigue. No cardiac toxicity was seen. Best overall responses (RECIST) were a complete response for one patient, partial responses for 10 patients, and stable disease for four patients. Conclusions Farletuzumab plus carboplatin/pegylated liposomal doxorubicin in women with platinum-sensitive EOC demonstrated a safety profile consistent with that of carboplatin plus pegylated liposomal doxorubicin. PMID

  17. High specific activity platinum-195m

    DOEpatents

    Mirzadeh, Saed; Du, Miting; Beets, Arnold L.; Knapp, Jr., Furn F.

    2004-10-12

    A new composition of matter includes .sup.195m Pt characterized by a specific activity of at least 30 mCi/mg Pt, generally made by method that includes the steps of: exposing .sup.193 Ir to a flux of neutrons sufficient to convert a portion of the .sup.193 Ir to .sup.195m Pt to form an irradiated material; dissolving the irradiated material to form an intermediate solution comprising Ir and Pt; and separating the Pt from the Ir by cation exchange chromatography to produce .sup.195m Pt.

  18. Perioperative allergy: uncommon agents.

    PubMed

    Caimmi, S; Caimmi, D; Cardinale, F; Indinnimeo, L; Crisafulli, G; Peroni, D G; Marseglia, G L

    2011-01-01

    Anesthesia may often be considered as a high-risk procedure and anaphylaxis remains a major cause of concern for anesthetists who routinely administer many potentially allergenic agents. Neuromuscular blocking agents, latex and antibiotics are the substances involved in most of the reported reactions. Besides these three agents, a wide variety of substances may cause an anaphylactic reaction during anesthesia. Basically all the administered drugs or substances may be potential causes of anaphylaxis. Among them, those reported the most in literature include hypnotics, opioids, local anesthetics, colloids, dye, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), Iodinated Contrast Media (ICM), antiseptics, aprotinin, ethylene oxyde and formaldehyde, and protamine and heparins. No premedication can effectively prevent an allergic reaction and a systematic preoperative screening is not justified for all patients; nevertheless, an allergy specialist should evaluate those patients with a history of anesthesia-related allergy. Patients must be fully informed of investigation results, and advised to provide a detailed report prior to future anesthesia. PMID:22014927

  19. Intelligent Agents: It's Nice To Get Stuff Done for You.

    ERIC Educational Resources Information Center

    Perez, Ernest

    2002-01-01

    Explains intelligent agents, special software tools that help make the Web more interactive by helping with information retrieval. Describes major types of agents, including search agents and agents for specialized tasks including monitors and knowledge management; and lists relevant Web sites. (LRW)

  20. Structure and Chemistry of Nickel Oxide-Nickel Platinum-Platinum Interfaces

    NASA Astrophysics Data System (ADS)

    Yang, Judith Chun-Hsu

    Recent investigations have demonstrated that interfacial reactions can be used to modify the mechanical strength of metal-ceramic interfaces. To better understand this phenomena, the structure and chemistry of model metal-ceramic interfaces, formed by diffusion bonding single crystals of NiO and Pt together, were studied using electron microscopy techniques. Lattice imaging shows that the interface structure between NiO and Pt may facet depending on the relative twist geometry between them. As suggested by Ni-Pt phase diagrams and previous work, suitable choice of annealing temperature, time and oxygen partial pressure allows the formation of the intermetallic compound NiPt. Conventional transmission electron microscope (CTEM) studies reveal the presence of a 0-20 nm thick NiPt interlayer after heat treatment at low oxygen activities. Electron energy loss spectroscopy (EELS) investigations showed that the nickel diffuses into the platinum for 100nm. Some thermodynamic and kinetic information of the NiPt formation at the NiO -Pt interface, based on the CTEM and EELS studies, is presented. The influence of crystallography, impurities and oxygen activity on the interfacial reactions were investigated. In the (100)_{NiO}//(100)_ {Pt} system, a NiPt layer forms along the interface. Whereas in the (100)_{NiO }//(111)_{Pt} system, NiPt particles appear within the Pt matrix. The growth of the intermetallic interlayer is also sensitive to impurities. The presence of silicon impurities in the heat treatment furnace reduces the thickness of the NiPt interlayer by nearly a factor of ten. The NiPt interlayer may or may not form due to slight changes in the oxygen activity of the heat treatment. A simple bonding model was previously proposed to explain why NiPt improves the interfacial shear strength. That is, the NiPt layer prevents the formation of weak Pt-O bonds. In order to experimentally check this model, NiPt -NiO interface planes, produced by internal oxidation in order