Effect of arm position on image quality and radiation dose during thorax and abdomen computed tomography scans.

INTRODUCTION: During Computed Tomography (CT) scans of the Thorax-Abdomen-Pelvis (TAP) the patient's arms should be positioned above the head to obtain optimal image quality and expose the patient to the lowest possible radiation dose. This may be impossible with patients with shoulder problems leading to arms being positioned in other ways. This study aimed to investigate differences in objective image quality and estimated effective dose (E), when positioning the arms below shoulder level in CT-TAP. METHODS: An anthropomorphic phantom with cadaver arms was used. Four arm positions were tested: Along the torso (A), on the pelvis (B), on a pillow on the pelvis (C), and one arm on pillow on the pelvis and the other arm on the pelvis (D). A Siemens SOMATOM Definition Flash CT-scanner with CareDose 4D was used. The dose length product was read to estimate E. Image quality was assessed objectively by measuring noise within the region of interest in the liver and urinary bladder. RESULTS: Significant differences in E between all arm positions were seen (p = 0.005). The lowest E was obtained in position C, reducing E by 8.42%. Position A provided the best image quality but the highest E. CONCLUSION: This study showed no unequivocal optimal positioning of arms in CT-TAP. Position A provided the best object image quality, while position C yielded the lowest E. These results may impact the planning of diagnostic CT where positioning of arms may influence optimal image quality and radiation dose. IMPLICATION FOR PRACTICE: This study illustrates tendencies for objective image quality and E when arms are positioned below shoulder level. Further research is needed to assess the clinical relevance with the diagnostic potential.

Phylogenetic relationships and further unknown diversity of diplostomids (Diplostomida: Diplostomidae) parasitic in kingfishers.

Kingfishers (Alcedinidae Rafinesque) are common inhabitants of wetlands and are known to be definitive hosts to a wide range of digeneans that parasitize fish as second intermediate hosts. Among these digeneans, members of the Diplostomidae Poirier, 1886 (diplostomids) are particularly common. Recent studies of diplostomids collected from kingfishers have revealed that they are probably more diverse than currently known. This particularly concerns the genera Crassiphiala Van Haitsma, 1925 and Uvulifer Yamaguti, 1934. In the present work, we studied seven diplostomid taxa from kingfishers in Brazil, the USA and the Philippines. Partial DNA sequences of the nuclear large ribosomal subunit (28S) and mitochondrial cytochrome c oxidase I (cox1) genes were obtained, and 28S sequences were used to study the phylogenetic interrelationships of these diplostomids. We provide the first DNA sequences from Uvulifer semicircumcisus Dubois et Rausch, 1950 and a member of Subuvulifer Dubois, 1952. Pseudocrassiphiala n. gen. is erected for a previously recognized species-level lineage of Crassiphiala and a new generic diagnosis of Crassiphiala is provided. Crassiphiala jeffreybelli n. sp., Crassiphiala wecksteini n. sp. and Pseudocrassiphiala tulipifera n. sp. are described, and a description of newly collected, high-quality specimens of Crassiphiala bulboglossa Van Haitsma, 1925 (the type-species of the genus) is provided.

DNP-NMR of surface hydrogen on silicon microparticles.

Dynamic nuclear polarization (DNP) enhanced nuclear magnetic resonance (NMR) offers a promising route to studying local atomic environments at the surface of both crystalline and amorphous materials. We take advantage of unpaired electrons due to defects close to the surface of the silicon microparticles to hyperpolarize adjacent 1H nuclei. At 3.3 T and 4.2 K, we observe the presence of two proton peaks, each with a linewidth on the order of 5 kHz. Echo experiments indicate a homogeneous linewidth of ∼150-300 Hz for both peaks, indicative of a sparse distribution of protons in both environments. The high frequency peak at 10 ppm lies within the typical chemical shift range for proton NMR, and was found to be relatively stable over repeated measurements. The low frequency peak was found to vary in position between -19 and -37 ppm, well outside the range of typical proton NMR shifts, and indicative of a high-degree of chemical shielding. The low frequency peak was also found to vary significantly in intensity across different experimental runs, suggesting a weakly-bound species. These results suggest that the hydrogen is located in two distinct microscopic environments on the surface of these Si particles.

Sign reversal of magnetoresistance and inverse spin Hall effect in doped conducting polymers.

Conducting polymers, where pristine polymers are doped by active dopants, have been used in a variety of flexible optoelectronic device applications due to their tunable conductivity values. Charge transport in these materials has been intensively studied for over three decades. However, spin transport properties in these compounds have remained elusive. Here, we studied two polaron-dominated and trap-dominated spin transport processes in two types of PEDOT:PSS polymers that are lightly and heavily doped, respectively. Using pulsed spin-pumping and spin-injection techniques, we found the sign of inverse spin Hall effect and magnetoresistance obtained from the lightly doped PEDOT:PSS film can reverse its polarity as a function of temperature and applied bias, in contrast to that in the heavily doped PEDOT:PSS film. Our work provides an alternative approach for studying the spin transport in conducting polymer films.

Hexacyanobutadienide-Based Frustrated and Weak Ferrimagnets: M(HCBD)2·zCH2Cl2 (M = V, Fe).

Hexacyanobutadiene (HCBD) and M(CO)x (M = V, x = 6; Fe, x = 5) react in CH2Cl2 to form new organic-based magnets of M[HCBD]2·z(CH2Cl2) composition. Analysis of the IR spectrum [M = V: ν(CN) 2193 and 2116 cm(-1) (fwhh ∼400 cm(-1)); Fe: 2196 and 2145 (fwhh ∼150 cm(-1))] suggests that HCBD is reduced to the radical anion, [HCBD](•-), and the broadness suggests multiple and variable nitriles sites are coordinated to the V(II), leading to a complex mixture of magnetic couplings and behaviors that deviate from paramagnetic behavior below ∼150 K, and a frustrated magnet with Tc ≈ 9 K is observed for V[HCBD]2, the first cyanocarbon-based frustrated magnet. Fe[HCBD]2 behaves as a weak ferromagnet (canted antiferromagnet) with some spin glass behavior with a 10 K Tc.

Characterization of Tetracyanopyridine (TCNPy)-Based Magnets: V[TCNPy]2 ⋠z (CH2 Cl2 ) (Tc =111†K) and V[TCNPy]3 ⋠z (CH2 Cl2 ) (Tc =90†K).

The reaction of 2,3,5,6-tetracyanopyridine (TCNPy) with V(CO)6 in CH2 Cl2 forms new organic-based magnets of V[TCNPy]x ⋅z (CH2 Cl2 ) (x=2, 3) composition. Analysis of the IR spectra suggests that the TCNPy is reduced and coordinated to V(II) sites through the nitriles. V[TCNPy]x order as ferrimagnets with 111 and 90 K Tc values for V[TCNPy]2 and V[TCNPy]3 , respectively. Their respective remanent magnetizations and coercive fields are 1260 and 250 emuOe mol(-1) and 9 and 6 Oe at 5 K, and they exhibit some spin-glass behavior.

The Tetracyanopyridinide Dimer Dianion, σ-[TCNPy]2 (2.).

The reaction of 2,3,5,6-tetracyanopyridine (TCNPy) and Cr(C6 H6 )2 forms diamagnetic σ-[TCNPy]2 (2-) possessing a 1.572(3) Šintrafragment sp(3) -sp(3) bond. This is in contrast to the structurally related 1,2,4,5-tetracyanobenzene and 1,2,4,5-tetracyanopyrazine that form π-dimer dianions possessing long, multicenter bonds.

Inverse spin Hall effect from pulsed spin current in organic semiconductors with tunable spin-orbit coupling.

Exploration of spin currents in organic semiconductors (OSECs) induced by resonant microwave absorption in ferromagnetic substrates is appealing for potential spintronics applications. Owing to the inherently weak spin-orbit coupling (SOC) of OSECs, their inverse spin Hall effect (ISHE) response is very subtle; limited by the microwave power applicable under continuous-wave (cw) excitation. Here we introduce a novel approach for generating significant ISHE signals in OSECs using pulsed ferromagnetic resonance, where the ISHE is two to three orders of magnitude larger compared to cw excitation. This strong ISHE enables us to investigate a variety of OSECs ranging from π-conjugated polymers with strong SOC that contain intrachain platinum atoms, to weak SOC polymers, to C60 films, where the SOC is predominantly caused by the curvature of the molecule's surface. The pulsed-ISHE technique offers a robust route for efficient injection and detection schemes of spin currents at room temperature, and paves the way for spin orbitronics in plastic materials.

Probing long-range carrier-pair spin-spin interactions in a conjugated polymer by detuning of electrically detected spin beating.

Weakly coupled electron spin pairs that experience weak spin-orbit interaction can control electronic transitions in molecular and solid-state systems. Known to determine radical pair reactions, they have been invoked to explain phenomena ranging from avian magnetoreception to spin-dependent charge-carrier recombination and transport. Spin pairs exhibit persistent spin coherence, allowing minute magnetic fields to perturb spin precession and thus recombination rates and photoreaction yields, giving rise to a range of magneto-optoelectronic effects in devices. Little is known, however, about interparticle magnetic interactions within such pairs. Here we present pulsed electrically detected electron spin resonance experiments on poly(styrene-sulfonate)-doped poly(3,4-ethylenedioxythiophene) ( PEDOT: PSS) devices, which show how interparticle spin-spin interactions (magnetic-dipolar and spin-exchange) between charge-carrier spin pairs can be probed through the detuning of spin-Rabi oscillations. The deviation from uncoupled precession frequencies quantifies both the exchange (<30 neV) and dipolar (23.5±1.5 neV) interaction energies responsible for the pair's zero-field splitting, implying quantum mechanical entanglement of charge-carrier spins over distances of 2.1±0.1 nm.

Coherent magnetic resonance of nanocrystal quantum-dot luminescence as a window to blinking mechanisms.

Blinking of colloidal nanocrystal quantum dots, random intermittency in the stream of photons emitted by single particles, has long commanded the curiosity of researchers. Why does the particle suddenly shut off, and what are the pathways to quench emission? Single-particle microscopy is not the only way to approach these fundamental questions on the interaction of light and matter: time-domain sub-ensemble spectroscopies can also yield relevant information on microscopic electronic processes. We illustrate recent advances in pulsed optically detected magnetic resonance and highlight the conceptual relevance to unravelling mechanisms controlling intermittency on the single-particle level. Magnetic resonance reveals two distinct luminescence quenching channels, which appear to be related to those previously surmised from single-particle studies: a trapped charge-separated state in which the exciton is quenched by dissociation and the particle remains neutral; and a charged state of the particle in which spin-dependent Auger recombination quenches luminescence.

Spin-dependent exciton quenching and spin coherence in CdSe/CdS nanocrystals.

Large surface-to-volume ratios of semiconductor nanocrystals cause susceptibility to charge trapping, which can modify luminescence yields and induce single-particle blinking. Optical spectroscopies cannot differentiate between bulk and surface traps in contrast to spin-resonance techniques, which in principle avail chemical information on such trap sites. Magnetic resonance detection via spin-controlled photoluminescence enables the direct observation of interactions between emissive excitons and trapped charges. This approach allows the discrimination of three radical species located in two functionally different trap states in CdSe/CdS nanocrystals, underlying the fluorescence quenching and thus blinking mechanisms: a spin-dependent Auger process in charged particles; and a charge-separated state pair process, which leaves the particle neutral. The paramagnetic trap centers offer control of the energy transfer yield from the wide-gap CdS to the narrow-gap CdSe, that is, light harvesting within the heterostructure. Coherent spin motion within the trap states of the CdS arms of nanocrystal tetrapods is reflected by spatially remote luminescence from CdSe cores with surprisingly long coherence times of >300 ns at 3.5 K, illustrating coherent control of light harvesting.

Light-harvesting action spectroscopy of single conjugated polymer nanowires.

We study exciton migration in single molecular nanowires, dye-endcapped multichromophoric conjugated polymers, as a function of excitation energy. This approach reveals the actual molecular absorption properties, uncovering the molecules within an ensemble and the chromophores within a molecule which contribute to absorption at a given wavelength. As the excitation energy is raised, an increasing number of polymers exhibit energy transfer suggesting that, in contrast to the emission spectrum, the absorption of a single chain under energy transfer conditions can be very broad even at 5 K. At the same time, the polarization anisotropy in excitation decreases due to an increase in the number of noncolinear chromophores involved in absorption. Power and wavelength-dependent measurements clearly discern the exciton blockade effect that gives rise to strong fluctuations of energy transfer. Although the polymer and endcap constitute nominally discrete spectroscopic entities, we are able to identify a subtle influence of the primary backbone exciton energy on the ultimate endcap emission. This demonstration of interchromophoric cooperativity provides a direct realization of how nonradiative energy dissipation in one nanoscale unit influences the spectroscopy of another.

The role of solid nanoparticle technology in the parenteral delivery of poorly water-soluble drugs.

Water insolubility has always been a key obstacle in pharmaceutical formulation, affecting formulation stability and drug bioavailability. Approaches for achieving complete dissolution often have disadvantages associated with the large quantities of required excipients. Small-particle suspensions (200 nm-2 microm), consisting essentially of pure drug, require only a minimum amount of surface-active agent for stabilization. Such suspensions may be formulated for rapid dissolution, thus achieving pharmacokinetic properties similar to those of a solution, or drug insolubility may be leveraged to afford prolonged in vivo release. In both situations, higher dosing may be possible than with a drug solution. This may afford enhanced efficacy at reduced excipient concentrations with potentially less toxicity. We present a brief introduction to the pharmaceutical technology of pure submicron drug particles in relationship to other dosage forms, and study examples are presented to underscore the potential benefits of this approach in parenteral delivery.

Estradiol, in the CNS, targets several physiologically relevant membrane-associated proteins.

We will describe the identity and function of two unexpected estrogen binding proteins from rat brain cell membranes in search for the putative membrane estrogen receptor (mER). An E-6-BSA column retained a distinctive 37-kDa protein that showed 100% homology with glyceraldehyde-3-phosphate dehydrogenase (GAPDH). A P-3-BSA column also retained the same protein but with less affinity. E-6-BSA bound to GAPDH with an IC50 of 50 nM, whereas the IC50 for P-3-BSA was about 500 nM. A dose of 10 nM 17beta-estradiol stimulated the catalysis of GAPDH, whereas progesterone at 100 nM inhibited it. Other steroids were ineffective. We examined if GAPDH activity would change during the rat estrous cycle, and what would be the effect of ovariectomy and estrogen treatment. The hippocampus and cerebellum were collected and GAPDH catalysis in both cytosolic and plasmalemmal-microsomal fractions was tested. The highest activity was found in Proestrus morning and the lowest in Estrus in both fractions. After ovariectomy (3 weeks) the hippocampus membrane fraction showed significantly reduced activity compared to that of Diestrus. An injection of estradiol in ovariectomized rats (10 microg/rat, s.c.) increased GAPDH activity in the hippocampus membrane fractions close to 60% from that of ovariectomized oil-treated controls 24 h after treatment maintaining similar levels by 48 h. No changes were detected in the preparations from the cerebellum of the same rats. The other protein retained by E-BSA columns was a 55-kDa protein identified as beta-tubulin. Two other proteins were also co-purified from the rat hippocampus: a 37-kDa (GAPDH) and a 45-kDa (actin). A purified brain tubulin (Cytoskeleton) was also retained with high affinity by the E-6-BSA, but with less affinity by an E-17-BSA column and not retained by either BSA, P-3-BSA or C-21-BSA columns. E-6-[125I]BSA bound with high affinity to tubulin (1 microg) and 17beta-estradiol completely displaced the binding at 10(-7) M. 17alpha-estradiol was ineffective and neither progesterone, corticosterone, DES nor 2-methoxyestradiol (2-ME) was able to displace the ligand. The T-3-[125I]BSA also bound to tubulin. But it seems to interact with another binding site, because colchicine at 10(-5) M completely eliminated the binding of T-3-[125 I]BSA to tubulin but did not displace the E-6-BSA site. Taxol competed off both ligands but only by 50%. None of the two ligands bound actin. These novel findings add new information to be considered in the intracellular actions of estradiol, particularly in the remodeling and functions of the cytoskeleton.

Effect of estradiol, diethylstilbestrol, and resveratrol on F0F1-ATPase activity from mitochondrial preparations of rat heart, liver, and brain.

The question of whether estrogens or estrogen-like compounds would alter differentially the enzymatic activity of the FOF1-ATPase was addressed. Mitochondrial fractions of the liver, brain, and heart were obtained from adult male rats and solubilized by digitonin. About 85% of the adenosine triphosphate hydrolysis by these three preparations come from the mitochondrial FOF1-ATPase. The enzymatic activity differed in the following order: liver < brain < heart. A concentration of 13 nM estradiol stimulated the FOF1-ATPase activity in heart by 10% (p < 0.01), but not in liver or brain. 17beta-estradiol competed off the binding of estradiol-17beta-17-(O-carboxymethyl)oxime:125I-labeled bovine serium albumin to mitochondrial preparations of the heart, revealing two binding sites. Resveratrol inhibited the F0F1-ATPase activity in both heart and liver with an IC50 of 13-15 microM, which confirmed our previous report in preparations of brain. Lower doses (picomolar to nanomolar) of resveratrol stimulated the FOF1-ATPase activity in liver by 10% but not in heart. At 6.7 microM, diethylstilbestrol (DES) inhibited the FOF1-ATPase activity in the three preparations by 61-67%. This study demonstrates that estradiol activates rat heart mitochondrial FOF1-ATPase at physiologic concentrations and that the FOF1-ATPase activity is markedly different in rat liver, brain, and heart. In addition, estradiol, DES, and resveratrol alter the FOF1-ATPase activity selectively, probably via different mechanisms.

[Hysterical symptoms and the body in old age]. / Hysterische Symptome und der Körper im Alter.

The psychological significance of the body changes in the course of a person's life. Using clinical cases it was examined how conversion symptoms influence these changes. Elder patients having conversion symptoms hardly perceive the aging processes of the body. Based on the assumption that the body self develops in the course of a life through internalization processes and that the body scheme is influenced and becomes more concrete through cognitive processes (e.g. experiences with illness) the body self and the body scheme become increasingly separate. The conversion with pseudoneurological symptoms is characterized by the cognitively perceived body image, the body scheme, through which normally also the aging processes become conscious. Since the conversion requires the body scheme to portray psychic conflicts the somatogenic organization function (Heuft) is repealed and as a result the aging processes of the body and therefore aging are not dealt with adequately.

A pilot study on home visiting in Aspen Community Care Services.

The aim of this study was to test a questionnaire for more detailed management information of a community care program in rural Alberta. A total of 24 community care clients and 486 home visits to these clients were assessed. The Client Homebound Score (CHS) and the Case Management Intensity Score (CMIS) were positively associated with time spent on home visits. These scores would be useful indicators for improved resource-based planning of home visiting.

BrdUrd-induced radiosensitization of two human tumour cell lines at iso-levels of incorporation.

Bromodeoxyuridine (BrdUrd)-induced radiosensitization of two different tumour cell lines was compared at equal levels of thymidine replacement. Human lung carcinoma cells (SW-1573) and human colorectal carcinoma cells (RKO) were grown for 48 h in the presence of respectively 1 microM BrdUrd and 4 microM of BrdUrd in order to obtain equal levels of BrdUrd into the DNA. In SW cells the level of thymidine replacement by BrdUrd was 6.7+/-0.5% and in RKO cells this was 7.1+/-0.8. Cell survival after irradiation with single doses up to 8 Gy, was determined with clonogenic assay. The magnitude of BrdUrd-induced radiosensitization was determined by analyzing radiation-dose survival curves with the linear-quadratic formula [S(D)/S(0)=exp-(alphaD+betaD2)]. In the SW cells BrdUrd radiosensitization led to a significant increase of the linear parameter, alpha, determining the initial slope of the survival curves, by a factor of about 2. In the RKO cells BrdUrd increased the value of alpha by a factor 1.4. This suggests that repair of potentially lethal damage (PLD) is inhibited. In both cell lines the quadratic term, beta, strongly influencing the high dose region of the survival curves, was not altered by sensitization by BrdUrd. The increase of alpha is of interest for clinical applications as BrdUrd sensitizes tumour cells after low doses of radiation.