Reduction of rheniumV oxo Schiff base complexes with triethylphosphine

Abstract only availablePioneering techniques for therapeutic treatment of cancers involve targeting cancer sites with strong beta-emitting radionuclides, thereby destroying the cancer cells. This is achieved by coordinating the radioisotope to a very chemically stable environment and linking it to a specific biologically active targeting molecule, which interacts with particular cancer cells. Radioactive isotopes of rhenium possess characteristics of such a nuclide. The focus of our research is to investigate two possible pathways for the reaction of [ReOX(Schiff base)] with phosphine ligands, one a mono-substituted ReV complex and one a di-substituted ReIII complex. The preferred ReIII complex is lower in oxidation state and more kinetically inert or stable relative to ReV. For practical applications it is necessary to have an extremely stable in vivo radionuclide complex which can be conjugated to a suitable biological targeting agent. The rigid sal2phen ligand, where Sal2phen is a tetradentate Schiff base ligand, was investigated to determine if the ReIII could be synthesized from the ReV starting complex [ReVOCl(Sal2phen)]. [ReVOCl(Sal2phen)] was reacted with triethylphosphine (PEt3) in attempts to yield the ReIII complex trans-[ReIII(PEt3)2(Sal2phen)][X]. Previous work indicated that the strongly reducing and strongly nucleophilic PEt3 might yield the ReV product from [ReVOCl(Sal2phen)]. The synthesized coordinated complex was reacted with an quaternary ammonium salt, ammonium hexaflurophosphate (NH4PF6), to induce crystallization of target compound [ReIII(PEt3)2(Sal2phen)][PF6]. Preliminary 1H-NMR, 31P-NMR, and infrared spectroscopy spectra indicate the formation of cis-[ReVO(PPh3)(Sal2phen)][X]. FTIR shows the presence of the Rhenium oxo group; 31P-NMR and 1H-NMR indicate the presence of ReV and a 1:1 PEt3 : Sal2phen complex. Single crystal x-ray diffraction, mass spectroscopy, and elemental analysis are additional methods of characterization.NSF-REU/NIH Program in Radiochemistr

OPT3 is a component of the iron-signaling network between leaves and roots and misregulation of OPT3 leads to an over-accumulation of cadmium in seeds.

Plants and seeds are the main dietary sources of zinc, iron, manganese, and copper, but are also the main entry point for toxic elements such as cadmium into the food chain. We report here that an Arabidopsis oligopeptide transporter mutant, opt3-2, over-accumulates cadmium (Cd) in seeds and roots but, unexpectedly, under-accumulates Cd in leaves. The cadmium distribution in opt3-2 differs from iron, zinc, and manganese, suggesting a metal-specific mechanism for metal partitioning within the plant. The opt3-2 mutant constitutively up-regulates the Fe/Zn/Cd transporter IRT1 and FRO2 in roots, indicative of an iron-deficiency response. No genetic mutants that impair the shoot-to-root signaling of iron status in leaves have been identified. Interestingly, shoot-specific expression of OPT3 rescues the Cd sensitivity and complements the aberrant expression of IRT1 in opt3-2 roots, suggesting that OPT3 is required to relay the iron status from leaves to roots. OPT3 expression was found in the vasculature with preferential expression in the phloem at the plasma membrane. Using radioisotope experiments, we found that mobilization of Fe from leaves is severely affected in opt3-2, suggesting that Fe mobilization out of leaves is required for proper trace-metal homeostasis. When expressed in yeast, OPT3 does not localize to the plasma membrane, precluding the identification of the OPT3 substrate. Our in planta results show that OPT3 is important for leaf phloem-loading of iron and plays a key role regulating Fe, Zn, and Cd distribution within the plant. Furthermore, ferric chelate reductase activity analyses provide evidence that iron is not the sole signal transferred from leaves to roots in leaf iron status signaling

Comparison of different methods for removing metals from resins for applications to radiochemical seperations

Abstract only availableMetallic contamination has been a problem for many years in the environmental field. Soil, water and air have been polluted by many different trace metals that finally affect humans by consumption of natural products, liquids and simple respiration, and have the potential of producing some toxicity in the body, leading to different illnesses such as cancer. On the other hand medical and scientific studies have found many metals such as the radiolanthanides and M(3+) metals, to be useful for therapeutic purposes, including cancer treatment, and targeting specific organs in the human body by the use of radioactive isotopes. The overall goal of this project was to compare the different techniques for cleaning various resins being used in the production of radiolanthanides at MURR. This was done to determine what metals and in what quantities these metals were removed by each method. Resins are known to contain extraneous metals such as copper, zinc, calcium and iron, which can leach out of the resin and contaminate the sample of interest resulting in low radiolabeling yields. The methods examined were different acid washes of various molarities and the use of different ligand systems (chelators) to determine which method would remove the most metals without affecting the resolving power of the resins. A variety of resins that are being investigated for performing separations, extractions and clean up of radiolanthanides of interest for radiotherapy were examined. Radiolanthanides are being developed and bound to biomolecular targeting agents to treat and provide palliative care for a variety of cancers. The purity of these radiolanthanides are essential as impurities in the original target material can result in unwanted impurities that can lead to environmental waste issues and dose concerns to workers and patients. In addition, since the chelates that attach these radiolanthanides to the targeting molecule are nonselective and will bind all +3 and many +2 metals, this would lead to low radiolabeling yields and therefore result in a lower dose being delivered to the target organ. The radiopharmaceutical developed by means of this procedure is one that selectively targets only a certain receptor and effectively irradiates only the tumor without affecting the surrounding organs. Thus is a non-invasive treatment that is better tolerated by the patients, as compared to other treatment methods such as chemotherapy, radiation treatments and surgery. The resins were washed and the eluents analyzed by ICP-MS (Inductively Coupled Plasma Mass Spectrometry). This technique determines the amount of metals present in the eluents collected from each wash. The elements expected to be found in these samples are the common metals found in the environment, like iron, calcium, aluminum, zinc, chromium, copper, nickel, etc. Furthermore, by performing simple radiolabeling studies with Lutetium-177 and 1,4,7,10-tetraazaciclododecane-1,4,7,10-tetraacetic acid (DOTA), a ligand commonly used to bind radiolanthanides, the washes were compared. The percentage labeled complex was compared to evaluate which method resulted in the best extraction of unwanted metals.NSF-REU Radiochemistr

Reduction of rhenium (V) oxo Schiff Base Complexes with triphenyl phosphine ligands

Abstract only availableOne approach to the treatment of cancer is to direct beta-emitting radionuclide to the cancer site where the radiation destroys the cancer cells. This can be achieved by coordinating the radioisotope in a very stable environment and linking it to a specific biological targeting molecule, which interacts specifically with particular cancer cells. It is necessary to have extremely stable in vivo radionuclide complexes so that limited amounts of radiation are released to other parts of the body before the radionuclide can reach the cancer cells. Isotopes of radioactive Rhenium are characteristic of such a nuclide. Our emphasis was to obtain a Rhenium (III) metal ligand complex since the lower oxidation state is more kinetically inert relative to Rhenium (V). The method employed was to first produce the ReV-ligand complex, [ReVOCl(Sal2phen)], by reacting a 1:2 molar ratio of TBA[ReVIIOCl4] to Sal2phen. Next, [ReVOCl(Sal2phen)] was reacted with three equivalents of triphenylphosphine to determine whether a mono-substituted ReV complex or a di-substituted ReIII complex was formed. After purifying the product by solvent extraction, the coordinated complex was reacted with ammonium hexaflurophoshate, NH4PF6, to induce crystallization of the target compound, [ReIII(PPh3)2(Sal2phen)][PF6]. Preliminary 1H NMR, and FT-IT spectra suggest formation of trans-[ReIII(PPh3)2(sal2phen)]PF6. The Re=O stretch at 951.36 cm-1 observed for [ReOCl(sal2phen)] in the IR spectrum is missing from our product, implying the Re (III) product has been formed.Stevens' Chemistry Progra

Use of Motion Pictures in Laboratory Dynamical Studies

In student laboratory experiments in dynamics, as, for example, Newton\u27s second law of motion or the conservation of momentum, it is, of course, highly desirable to allow motion with the least possible constraint and to observe the displacements of moving parts without using perturbing markers. This circumstance has led us to use motion pictures in the student laboratory for quantitative observation of rapid dynamic processes, a technique which is used in a well-known textbook.\u27 The photographic method combines maximum freedom of movement with accurate observation of position as a function of time, if the camera frame speed is sufficiently high. A double pendulum apparatus, with which we have studied the conservation of momentum in the student laboratory, is shown in Fig. 1. It consists of two wooden blocks, each suspended by a steel rod from a common free-swing pivot and counter-weighted in such a way that the center of mass of each pendulum is at the center of its wooden block. A spring is compressed between the two blocks, and they are tied together with a thread. When this thread is burned, the pendulums recoil. The mass of each block can be varied at will. The motion is photographed with a motion picture camera at 64 frames per second. The camera used in this work was a war-surplus gun-point aiming camera, adapted only to the extent of adding a viewfinder. Since there is a coordinate screen behind the pendulums, the student can determine the heights to which the blocks rise by examining the film with a magnifying viewer

Use of Motion Pictures in Laboratory Dynamical Studies

In student laboratory experiments in dynamics, as, for example, Newton\u27s second law of motion or the conservation of momentum, it is, of course, highly desirable to allow motion with the least possible constraint and to observe the displacements of moving parts without using perturbing markers. This circumstance has led us to use motion pictures in the student laboratory for quantitative observation of rapid dynamic processes, a technique which is used in a well-known textbook.\u27 The photographic method combines maximum freedom of movement with accurate observation of position as a function of time, if the camera frame speed is sufficiently high. A double pendulum apparatus, with which we have studied the conservation of momentum in the student laboratory, is shown in Fig. 1. It consists of two wooden blocks, each suspended by a steel rod from a common free-swing pivot and counter-weighted in such a way that the center of mass of each pendulum is at the center of its wooden block. A spring is compressed between the two blocks, and they are tied together with a thread. When this thread is burned, the pendulums recoil. The mass of each block can be varied at will. The motion is photographed with a motion picture camera at 64 frames per second. The camera used in this work was a war-surplus gun-point aiming camera, adapted only to the extent of adding a viewfinder. Since there is a coordinate screen behind the pendulums, the student can determine the heights to which the blocks rise by examining the film with a magnifying viewer

A Systematic Literature Review with Meta-Analyses of Within- and Between-Day Differences in Objectively Measured Physical Activity in School-Aged Children

Background: Targeting specific time periods of the day or week may enhance physical activity (PA) interventions in youth. The most prudent time segments to target are currently unclear.  Objectives: To systematically review the literature describing differences in young people’s objectively measured PA on weekdays vs. weekends, in school vs. out of school, weekends vs. out of school and lesson time vs. break time.  Methods: Electronic databases were searched for English-language, cross-sectional studies of school-aged children (4–18 years) reporting time-segment-specific accelerometer-measured PA from 01/1990 to 01/2013. We meta-analysed standardised mean differences (SMD) between time segments for mean accelerometer counts per minute (TPA) and minutes in moderate-to-vigorous PA (MVPA). SMD is reported in units of standard deviation; 0.2, 0.5 and 0.8 represent small, moderate and large effects. Heterogeneity was explored using meta-regression (potential effect modifiers: age, sex and study setting).  Results: Of the 54 included studies, 37 were eligible for meta-analyses. Children were more active on weekdays than weekends [pooled SMD (95 % CI) TPA 0.14 (0.08; 0.20), MVPA 0.42 (0.35; 0.49)]. On school days, TPA was lower in school than out of school; however, marginally more MVPA was accumulated in school [TPA −0.24 (−0.40; −0.08), MVPA 0.17 (−0.03; 0.38)]. TPA was slightly lower on weekends than out of school on school days, but a greater absolute volume of MVPA was performed on weekends [TPA −0.10 (−0.19; −0.01), MVPA 1.02 (0.82; 1.23)]. Heterogeneity between studies was high (I2 73.3–96.3 %), with 20.3–53.1 % of variance between studies attributable to potential moderating factors.  Conclusions: School-aged children are more active on weekdays than weekend days. The outcome measure influences the conclusions for other comparisons. Findings support the tailoring of intervention strategies to specific time periods

Future and potential spending on health 2015-40 : development assistance for health, and government, prepaid private, and out-of-pocket health spending in 184 countries

Background The amount of resources, particularly prepaid resources, available for health can affect access to health care and health outcomes. Although health spending tends to increase with economic development, tremendous variation exists among health financing systems. Estimates of future spending can be beneficial for policy makers and planners, and can identify financing gaps. In this study, we estimate future gross domestic product (GDP), all-sector government spending, and health spending disaggregated by source, and we compare expected future spending to potential future spending. Methods We extracted GDP, government spending in 184 countries from 1980-2015, and health spend data from 1995-2014. We used a series of ensemble models to estimate future GDP, all-sector government spending, development assistance for health, and government, out-of-pocket, and prepaid private health spending through 2040. We used frontier analyses to identify patterns exhibited by the countries that dedicate the most funding to health, and used these frontiers to estimate potential health spending for each low-income or middle-income country. All estimates are inflation and purchasing power adjusted. Findings We estimated that global spending on health will increase from US$9.21 trillion in 2014 to$24.24 trillion (uncertainty interval [UI] 20.47-29.72) in 2040. We expect per capita health spending to increase fastest in upper-middle-income countries, at 5.3% (UI 4.1-6.8) per year. This growth is driven by continued growth in GDP, government spending, and government health spending. Lower-middle income countries are expected to grow at 4.2% (3.8-4.9). High-income countries are expected to grow at 2.1% (UI 1.8-2.4) and low-income countries are expected to grow at 1.8% (1.0-2.8). Despite this growth, health spending per capita in low-income countries is expected to remain low, at $154 (UI 133-181) per capita in 2030 and$195 (157-258) per capita in 2040. Increases in national health spending to reach the level of the countries who spend the most on health, relative to their level of economic development, would mean $321 (157-258) per capita was available for health in 2040 in low-income countries. Interpretation Health spending is associated with economic development but past trends and relationships suggest that spending will remain variable, and low in some low-resource settings. Policy change could lead to increased health spending, although for the poorest countries external support might remain essential.Peer reviewe