Peptide nanoconjugates for tissue diagnostics and molecular imaging

The rise of targeted therapy in cancer treatment has created a strong need for characterization of a patient's tumor before receiving treatment. Many effective cancer drugs are now being targeted to specific proteins present in the tumor, thus only patients who have tumors that express these proteins in appreciable amounts will respond to these kinds of therapy. The most popular method of diagnosing patients is through the practice of immunohistochemistry (IHC), where biopsied patient tissue is subjected to testing for specific protein expression. IHC works by incubating a primary antibody towards the target protein, followed by detection with a secondary antibody containing a reactive enzyme - most commonly, horseradish peroxidase (HRP). IHC procedures are expensive, comprises several steps, involves varying amounts of amplification due to enzyme reactivity, and is only as specific as the primary antibody. Patients receiving treatment using popular drugs targeted at common proteins such as EGFR, c-MET, and PD-L1 have shown varying degrees of responses based on initial IHC diagnosis, even when using FDA-approved diagnostic kits. Due to the discrepancies seen between diagnosis and drug efficacy, we have developed new methods utilizing gold nanoparticles that utilize peptides to target protein biomarkers in human tissues. Peptides which are targeted towards receptors contain only the amino acid sequences which are sufficient for protein binding. Due to their tailored specificity, low cost, scalable production, and ease of modification, peptides can be an attractive method of investigating protein content in human tissues. We investigated the use of peptides combined with imaging agents as diagnostic methods to compare with standard immunohistochemistry procedures. Gold nanorods (GNR) scatter light efficiently in the dark field, and their high surface-area-to-volume ratio allows each nanorod to be coated with many targeting peptides, enhancing specificity of each nanoparticle for the receptor of interest. We first investigated attachment of peptides to GNR that can be used to diagnose common biomarkers EGFR and cMET in tumor tissues. EGFR is one of the most commonly overexpressed proteins in human cancers, and many EGFR-targeted drugs have shown improvement of progression-free survival in patients. During the course of EGFR-targeted treatment it is common that a patient will eventually develop resistance to the EGFR-targeted drugs. One such mechanism is the circumventing of EGFR pathway through upregulation of the c-MET protein on the tumor surface. Once EGFR is internalized and c-MET is the dominant pathway, patients will stop responding to EGFR-targeted drug and the tumor will continue proliferation. There are numerous c-MET drugs on the market for second or third line therapy when resistance occurs with this mechanism, however diagnosis of the c-MET biomarker has become controversial due to poor diagnostic results using the current standard IHC methods. We thus followed up our EGFR diagnostic study by investigating the c-MET protein using the same GNR platform with a cMET-targeted peptide. The GNR-based histochemistry platform shows specificity for the targeted receptors in tumor cell lines and patient tissues, and is able to detect a range of protein expression, rather than relying on binary pathology grades of 1+,2+, or 3+ expression. EGFR and c-MET are two popular biomarkers targeted by pharmaceuticals, and have seen recent success when combined with immune checkpoint inhibitors. The current surge in immuno-oncology has shown excellent response of patients to drugs that inhibit common immune checkpoints such as the interaction between immune receptor Programmed Death 1 (PD-1), expressed on immune cells, and its ligand, PD-L1, expressed on tumor cells. The binding of PD-1 on T cells to PD-L1 on tumor cells will stop the T cells from destroying the tumor. Inhibition of immune checkpoints restore lost host immune function by allowing T-cells to recognize tumor cells as foreign. As with EGFR and c-MET, there has been much debate over whether current methods of diagnosing PD-L1 levels in patients are sufficient due to patient responses varying with respect to the diagnostic recommendation. We extended our peptidebased diagnostic method to investigate PD-L1 by analyzing the crystal structures of PD-L1 and PD-1 and synthesizing a peptide that is specific for the binding region of PD-L1. Using this sequence, we combined our PD-L1 peptide with a biotin molecule, to allow for conventional IHC, and a Cy5 fluorophore to conduct fluorescent investigations of PD-L1 levels in patient tumor tissues. When compared head-to-head with the current FDA-approved PD-L1 diagnostic standard, the peptide-based method shows high specificity for tumors in patient tissues that the FDA-approved diagnostic kits fail to recognize. Due to these results, we believe that peptide-based histochemistry can be used as a specific, cheap alternative to conventional antibody-based IHC

UBVRI Light Curves of 44 Type Ia Supernovae

We present UBVRI photometry of 44 type-Ia supernovae (SN Ia) observed from 1997 to 2001 as part of a continuing monitoring campaign at the Fred Lawrence Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics. The data set comprises 2190 observations and is the largest homogeneously observed and reduced sample of SN Ia to date, nearly doubling the number of well-observed, nearby SN Ia with published multicolor CCD light curves. The large sample of U-band photometry is a unique addition, with important connections to SN Ia observed at high redshift. The decline rate of SN Ia U-band light curves correlates well with the decline rate in other bands, as does the U-B color at maximum light. However, the U-band peak magnitudes show an increased dispersion relative to other bands even after accounting for extinction and decline rate, amounting to an additional ~40% intrinsic scatter compared to B-band.Comment: 84 authors, 71 pages, 51 tables, 10 figures. Accepted for publication in the Astronomical Journal. Version with high-res figures and electronic data at http://astron.berkeley.edu/~saurabh/cfa2snIa

The DNA Damage Response Pathway Contributes to the Stability of Chromosome III Derivatives Lacking Efficient Replicators

In eukaryotic chromosomes, DNA replication initiates at multiple origins. Large inter-origin gaps arise when several adjacent origins fail to fire. Little is known about how cells cope with this situation. We created a derivative of Saccharomyces cerevisiae chromosome III lacking all efficient origins, the 5ORIΔ-ΔR fragment, as a model for chromosomes with large inter-origin gaps. We used this construct in a modified synthetic genetic array screen to identify genes whose products facilitate replication of long inter-origin gaps. Genes identified are enriched in components of the DNA damage and replication stress signaling pathways. Mrc1p is activated by replication stress and mediates transduction of the replication stress signal to downstream proteins; however, the response-defective mrc1AQ allele did not affect 5ORIΔ-ΔR fragment maintenance, indicating that this pathway does not contribute to its stability. Deletions of genes encoding the DNA-damage-specific mediator, Rad9p, and several components shared between the two signaling pathways preferentially destabilized the 5ORIΔ-ΔR fragment, implicating the DNA damage response pathway in its maintenance. We found unexpected differences between contributions of components of the DNA damage response pathway to maintenance of ORIΔ chromosome derivatives and their contributions to DNA repair. Of the effector kinases encoded by RAD53 and CHK1, Chk1p appears to be more important in wild-type cells for reducing chromosomal instability caused by origin depletion, while Rad53p becomes important in the absence of Chk1p. In contrast, RAD53 plays a more important role than CHK1 in cell survival and replication fork stability following treatment with DNA damaging agents and hydroxyurea. Maintenance of ORIΔ chromosomes does not depend on homologous recombination. These observations suggest that a DNA-damage-independent mechanism enhances ORIΔ chromosome stability. Thus, components of the DNA damage response pathway contribute to genome stability, not simply by detecting and responding to DNA template damage, but also by facilitating replication of large inter-origin gaps

Social change and the family: Comparative perspectives from the west, China, and South Asia

This paper examines the influence of social and economic change on family structure and relationships: How do such economic and social transformations as industrialization, urbanization, demographic change, the expansion of education, and the long-term growth of income influence the family? We take a comparative and historical approach, reviewing the experiences of three major sociocultural regions: the West, China, and South Asia. Many of the changes that have occurred in family life have been remarkably similar in the three settings—the separation of the workplace from the home, increased training of children in nonfamilial institutions, the development of living arrangements outside the family household, increased access of children to financial and other productive resources, and increased participation by children in the selection of a mate. While the similarities of family change in diverse cultural settings are striking, specific aspects of change have varied across settings because of significant pre-existing differences in family structure, residential patterns of marriage, autonomy of children, and the role of marriage within kinship systems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45661/1/11206_2005_Article_BF01124383.pd

Environmentalism, pre-environmentalism, and public policy

In the last decade, thousands of new grassroots groups have formed to oppose environmental pollution on the basis that it endangers their health. These groups have revitalized the environmental movement and enlarged its membership well beyond the middle class. Scientists, however, have been unable to corroborate these groups' claims that exposure to pollutants has caused their diseases. For policy analysts this situation appears to pose a choice between democracy and science. It needn't. Instead of evaluating the grassroots groups from the perspective of science, it is possible to evaluate science from the perspective of environmentalism. This paper argues that environmental epidemiology reflects ‘pre-environmentalist’ assumptions about nature and that new ideas about nature advanced by the environmental movement could change the way scientists collect and interpret data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45449/1/11077_2005_Article_BF01006494.pd

USGS Hurricane Storm-Surge Monitoring Networks: An Example from Hurricane Rita

2010 S.C. Water Resources Conference - Science and Policy Challenges for a Sustainable Futur