University of California Research Initiatives

In the current context of pervasive loss and the absence of publicly commemorative rituals, this essay proposes a reading of Freud’s ‘Mourning and Melancholia’ that questions the presupposition that mourning must come to an end as the completed work of memories recalled only to be sent off. While melancholia may be presented as the invention of an imaginary loss, would not the real pathology of mourning be the summary or precipitous declaration of its end? Whether we understand mourning as completable in itself or as impossibly seeking an asymptote it can never reach, whether the work of mourning is terminal or interminable, the name of the deceased stands as what is left, not only as what is inscribed on a gravestone and outlasting any living memory, but also as the very bounds of memory as sense. Not so much the end of mourning, then, as its reiterative reaffirmation, commemoration comes down to a practice of active mourning (like active forgetting), not an ‘end’ but its retreat, its appearing/disappearing as the incessant redrawing of its withdrawal. Not a self-deprecating melancholia, nor the indulgent luxury of nostalgia, but the endless inscription of a name whose loss we can never stop mourning.

The evolution of the placenta is an excellent model to examine the evolutionary processes underlying adaptive complexity due to the recent, independent derivation of placentation in divergent animal lineages. In fishes, the family Poeciliidae offers the opportunity to study placental evolution with respect to variation in degree of post-fertilization maternal provisioning among closely related sister species. In this study, we present a detailed examination of a new reference transcriptome sequence for the live-bearing, matrotrophic fish, Poeciliopsis prolifica, from multiple-tissue RNA-seq data. We describe the genetic components active in liver, brain, late-stage embryo, and the maternal placental/ovarian complex, as well as associated patterns of positive selection in a suite of orthologous genes found in fishes. Results indicate the expression of many signaling transcripts, "non-coding" sequences and repetitive elements in the maternal placental/ovarian complex. Moreover, patterns of positive selection in protein sequence evolution were found associated with live-bearing fishes, generally, and the placental P. prolifica, specifically, that appear independent of the general live-bearer lifestyle. Much of the observed patterns of gene expression and positive selection are congruent with the evolution of placentation in fish functionally converging with mammalian placental evolution and with the patterns of rapid evolution facilitated by the teleost-specific whole genome duplication event.

1D organic metal halide hybrids (OMHHs) exhibit strongly anisotropic optical properties, highly efficient light emission, and large Stokes shift, holding promise for novel photodetection and lighting applications. However, the fundamental mechanisms governing their unique optical properties and in particular the impacts of surface effects are not understood. Herein, 1D C4N2H14PbBr4 by polarization-dependent time-averaged and time-resolved photoluminescence (TRPL) spectroscopy, as a function of photoexcitation energy, is investigated. Surprisingly, it is found that the emission under photoexcitation polarized parallel to the 1D metal halide chains can be either stronger or weaker than that under perpendicular polarization, depending on the excitation energy. The excitation-energy-dependent anisotropic emission is attributed to fast surface recombination, supported by first-principles calculations of optical absorption in this material. The fast surface recombination is directly confirmed by TRPL measurements, when the excitation is polarized parallel to the chains. The comprehensive studies provide a more complete picture for a deeper understanding of the optical anisotropy in 1D OMHHs.

Stimuli responsive polymers are an efficient means of targeted therapy.  Compared to conventional agents, they increase bioavailability and efficacy.  In particular, polymer hydrogel nanoparticles (NPs) can be designed to respond when exposed to a specific environmental stimulus such as pH or temperature. However, targeting a specific metabolite as the trigger for stimuli response could further elevate selectivity and create a new class of bioresponsive materials.  In this work we describe an N-isopropylacrylamide (NIPAm) NP that responds to a specific metabolite characteristic of a hypoxic environment found in cancerous tumors.  NIPAm NPs were synthesized by copolymerization with an oxamate derivative, a known inhibitor of lactate dehydrogenase (LDH).  The oxamate functionalized NPs (OxNP) efficiently sequestered LDH to produce an OxNP-protein complex.  When exposed to elevated concentrations of lactic acid, a substrate of LDH and a metabolite characteristic of hypoxic tumor microenvironments, OxNP-LDH complexes swelled (65%).  The OxNP-LDH complexes were not responsive to structurally related small molecules.  This work demonstrates a proof of concept for tuning NP responsiveness by conjugation with a key protein to target a specific metabolite of disease.

Constructs derived from mammalian cells are emerging as a new generation of nano-scale platforms for clinical imaging applications. Herein, we report successful engineering of hybrid nano-structures composed of erythrocyte-derived membranes doped with FDA-approved near infrared (NIR) chromophore, indocyanine green (ICG), and surface-functionalized with antibodies to achieve molecular targeting. We demonstrate that these constructs can be used for targeted imaging of cancer cells in vitro. These erythrocyte-derived optical nano-probes may provide a potential platform for clinical translation, and enable molecular imaging of cancer biomarkers.

Multiple myeloma (MM) is an aggressive hematopoietic cancer of plasma cells. The recent emergence of three effective FDA-approved proteasome-inhibiting drugs, bortezomib (Velcade), carfilzomib (Kyprolis), and ixazomib (Ninlaro) confirms that proteasome inhibitors are therapeutically useful against neoplastic disease, in particular refractory MM and mantle cell lymphoma. This study describes the synthesis, computational affinity assessment, and preclinical evaluation of TIR-199, a natural product-derived syrbactin structural analog. Molecular modeling and simulation suggested TIR-199 covalently binds each of the three catalytic subunits (β1, β2 and β5) and revealed key interaction sites. In vitro and cell culture-based proteasome activity measurements confirmed that TIR-199 inhibits the proteasome in a dose-dependent manner and induces tumor cell death in multiple myeloma and neuroblastoma cells as well as other cancer types in the NCI-60 cell panel. It is particularly effective against kidney cancer cell lines, with more than 250-fold higher anti-tumor activities than observed with the natural product syringolin A (SylA). In vivo studies in mice revealed a maximum tolerated dose (MTD) of TIR-199 at 25 mg/kg. The anti-tumor activity of TIR-199 was confirmed in hollow fiber assays in mice. Adverse drug reaction screens in a kidney panel revealed no off-targets of concern. This is the first study to examine the efficacy of a syrbactin in animals. Taken together, the results suggest that TIR-199 is a potent new proteasome inhibitor with promise for further development into a clinical drug for the treatment of multiple myeloma and other forms of cancer.

The dynamics of relativistic electrons in the intense laser radiation and quasi-static electromagnetic fields both along and across the laser propagating direction are studied in the 3/2 dimensional (3/2D) Hamiltonian framework. It is shown that the unperturbed oscillations of the relativistic electron in these electric fields could exhibit a long tail of the amplitude of harmonics which makes an onset of stochastic electron motion be a primary candidate for electron heating. Chirikov-like mappings which describe the recurrence relations of electron energy and time passing through zero canonical momentum plane are derived, and then, the criteria for instability are obtained. It follows that for both transverse and longitudinal electric fields, there exist upper limits of the stochastic electron energy depending on the laser intensity and electric field strength. These maximum energies could be increased by a weak electric field. However, the maximum energy is reduced for the superluminal phase velocity in both cases. The impacts of the magnetic fields on the electron dynamics are different for these two cases and discussed qualitatively. These analytic results are confirmed by the numerical simulations of solving the 3/2D Hamiltonian equations directly.

The paper examines the legal and administrative history of the Sustainable Groundwater Act and assesses its potential for remedying overdraft.