Plasmonic Luneburg and Eaton lenses

Plasmonics takes advantage of the properties of surface plasmon polaritons, which are localized or propagating quasiparticles in which photons are coupled to the quasi-free electrons in metals. In particular, plasmonic devices can confine light in regions with dimensions that are smaller than the wavelength of the photons in free space, and this makes it possible to match the different length scales associated with photonics and electronics in a single nanoscale device. Broad applications of plasmonics that have been demonstrated to date include biological sensing, sub-diffraction-limit imaging, focusing and lithography and nano-optical circuitry. Plasmonics-based optical elements such as waveguides, lenses, beamsplitters and reflectors have been implemented by structuring metal surfaces or placing dielectric structures on metals to manipulate the two-dimensional surface plasmon waves. However, the abrupt discontinuities in the material properties or geometries of these elements lead to increased scattering of surface plasmon polaritons, which significantly reduces the efficiency of these components. Transformation optics provides an alternative approach to controlling the propagation of light by spatially varying the optical properties of a material. Here, motivated by this approach, we use grey-scale lithography to adiabatically tailor the topology of a dielectric layer adjacent to a metal surface to demonstrate a plasmonic Luneburg lens that can focus surface plasmon polaritons. We also make a plasmonic Eaton lens that can bend surface plasmon polaritons. Because the optical properties are changed gradually rather than abruptly in these lenses, losses due to scattering can be significantly reduced in comparison with previously reported plasmonic elements.     

Personality and aggressive behavior under provoking and neutral conditions: A meta-analytic review.

The authors conducted a comprehensive review to understand the relation between personality and aggressive behavior, under provoking and nonprovoking conditions. The qualitative review revealed that some personality variables influenced aggressive behavior under both neutral and provocation conditions, whereas others influenced aggressive behavior only under provocation. Studies that assessed personality variables and that directly measured aggressive behavior were included in the quantitative review. Analyses revealed that trait aggressiveness and trait irritability influenced aggressive behavior under both provoking and neutral conditions but that other personality variables (e.g., trait anger, Type A personality, dissipation-rumination) influenced aggressive behavior only under provoking conditions. The authors discuss possible relations between these patterns of aggressive behavior and the personality dimensions of Agreeableness and Neuroticism and consider implications for theories of aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Crosslinking of apolipoprotein E by products of lipid peroxidation

Apolipoprotein E (APOE) genotype and advancing aging are interacting ri sk factors in the expression of late onset and sporadic Alzheimer's Disease (AD). We tested the hypothesis that 2 products of lipid peroxidation, malondialdehyde (MDA) and 4 hydroxy-2-nonenal (HNE), covalently modify APOE and alter its metabolism. In vitro, both HNE and MDA crosslinked purified APOE3 and APOE4. HNE was a more potent crosslinker than MDA, and purified APO3 was more susceptible to crosslinking by HNE than was purified APOE4. In P19 neuroglial cultures, oxidative stress with lipid peroxidation led to increased intracellular accumulation of anti-HNE and anti-APOE immunoreactive proteins of approximately 50 kDa. Intercellular accumulation of the 50 kDa APOE-immunoreactive protein (APOE-50) was not prevented by cyclohexamide, suggesting formation by post-translational mechanisms. In CSF, a 50 kDa APOE-immunoreactive protein co-migrated with proteins most immunoreactive for HNE and MDA adducts, containing NaB3H4-reducible bonds. These proteins were in CSF from adult subjects (with or without dementia), and in AD patients homozygous for APOE3 or APOE4 alleles. These data suggest that HNE covalently crosslinks APOE in P19 neuroglial cultures to form a 50 kDa protein, and that similar modifications of APOE appear to occur in vivo.     

Salmonella typhimurium encodes an SdiA homolog, a putative quorum sensor of the LuxR family, that regulates genes on the virulence plasmid

OBJECTIVE: Despite improved systemic control of metastatic breast cancer, the incidence of brain metastases from breast carcinoma continues to rise, in part because most systemically administered agents have poor central nervous system penetration. Therefore, as a method of optimizing drug delivery into the central nervous system, we studied the safety and efficacy of chemotherapy delivered locally via biodegradable polymers in a mouse model of breast carcinoma metastases to the brain. METHODS: The chemotherapeutic agents carmustine (BCNU), carboplatin, and camptothecin were incorporated into controlled release polymers and tested individually against intracranial challenges of EMT-6 breast tumor in BALB/c female mice. For each drug, four groups were tested: Group 1, empty polymer (no drug); Group 2, external beam radiotherapy (XRT) alone; Group 3, local chemotherapy from biodegradable polymer alone; and Group 4, local chemotherapy and XRT together. Polymers were implanted 5 days after intracranial tumor inoculation; XRT was administered on Days 7 through 9 (300 cGy/d). RESULTS: BCNU polymer alone (n = 10; median survival time, >200 d; P < 0.0001) and BCNU and XRT together (n = 10; median survival time, 41 d; P = 0.02) significantly improved survival in mice with intracranial EMT-6 breast cancer in comparison with control animals (n = 20; median survival time, 17 d). Carboplatin and camptothecin, either with or without XRT, and XRT alone did not have any significant effect on survival. CONCLUSION: Local delivery of BCNU with biodegradable polymers can significantly prolong survival in a murine model of intracranial metastatic breast cancer. Surgical resection and placement of BCNU polymers into the resection cavity may decrease the incidence of local recurrence of breast cancer metastases with minimal morbidity.     

Analysis of potential risk factors associated with the development of pancreatitis in phase I patients with AIDS or AIDS-related complex receiving didanosine

Phase I dose-escalating trials of didanosine revealed dose-limiting toxicities, including pancreatitis, and established a total daily dose of 12.5 mg/kg/day as the maximum tolerated dose. Clinical and pharmacokinetic data of 61 patients from two trials were analyzed to further evaluate the risk of pancreatitis: 1 (6.3%) of 16 patients who received < 500 mg/day didanosine, 2 (13.3%) of 15 who received 500-750 mg/day, and 15 (50%) of 30 who received > 750 mg/day developed pancreatitis (P < .001). A relationship between risk of pancreatitis and steady-state plasma concentrations of didanosine and age was also observed, suggesting that knowledge of didanosine pharmacokinetics provided additional information regarding risk of toxicity. Further confirmation of these findings will be necessary to determine if the risk factors for pancreatitis remain the same at lower doses currently used.     

Plasminogen deficiency accelerates vessel wall disease in mice predisposed to atherosclerosis

A critical link between hemostatic factors and atherosclerosis has been inferred from a variety of indirect observations, including the expression of procoagulant and fibrinolytic factors within atherosclerotic vessels, the presence of fibrin in intimal lesions, and the cellular infiltration of mural thrombi leading to their incorporation into developing plaques. To directly examine the role of the key fibrinolytic factor, plasminogen, in atherogenesis, plasminogen-deficient mice were crossed to hypercholesterolemic, apolipoprotein E-deficient mice predisposed to atherosclerosis. We report that the loss of plasminogen greatly accelerates the formation of intimal lesions in apolipoprotein E-deficient animals, whereas plasminogen deficiency alone does not cause appreciable atherosclerosis. These studies provide direct evidence that circulating hemostatic factors strongly influence vessel wall disease in the context of a disorder in lipid metabolism.     

Spontaneous bilateral carotid and vertebral artery dissection presenting as a Collet-Sicard syndrome

Spontaneous dissection of the internal carotid arteries usually presents with unilateral headache, neck pain, focal ipsilateral cerebral ischaemic symptoms and a Horner's syndrome. Lower cranial nerve palsies are only rarely observed. We report a case of carotid and vertebral dissections presenting as a unilateral palsy of the ninth to twelfth cranial nerves (Collet-Sicard syndrome).     

Concerning the Radical Character of Superoxide. The H—O Bond Energy of HO−2

The strength of the H-O bond in H⁻O₂ should be a good indicator of the chemical reactivity of superoxide, O⁻₂, as a hydrogen atom abstractor. This quantity can be calculated if the electron affinity of HO₂ is known. A recent experimental determination of the electron affinity of HO₂ [V. M. Bierbaum, R. J. Schmitt and C. H. DePuy, J. Am. Chem. Soc., 103 , 6262–6263 (1981)] gave that value as 27.4 ± 0.2 kcal mol⁻¹. The H-O bond energy of HO⁻⁻₂ can then be calculated from that value to be approximately 66 kcal mol⁻¹. Various theoretical methods may also be used to approximate the value of the electron affinity of HO₂. These methods generally give values in accord with the experimental result. Based on the low H—O bond energy of 66 kcal mol⁻¹ for HO⁻₂, superoxide is expected to be relatively unreactive, comparable to iodine atoms but less reactive than bromine atoms or HO₂ and much less reactive than chlorine atoms or hydroxyl radicals. Based on our analysis, we predict that superoxide can only react as a hydrogen atom abstractor with substrates that contain relatively weak bonds to hydrogen such as hydroxylamine or hydroquinones.