Immunochemical recognition of A2E, a pigment in the lipofuscin of retinal pigment epithelial cells

Preparation of isodesmosine-KLH conjugate for ELISA system

Chronic obstructive pulmonary disease (COPD) is a degenerative condition with limited diagnostic detection efficiency. Currently with no available cure, COPD is associated with irreversible elastic tissue degradation in lungs, which results in release of unusual amino acids, isodesmosine and desmosine. These biomarkers are potential key elements in enzyme-linked immunosorbent assay (ELISA), an analytical method, which can detect certain compounds including antigens and proteins in easy and affordable manner. In order to target a biomarker with ELISA, it is necessary to prepare its specific antibody, which can be achieved by immunization of host organism with appropriate antigen containing the biomarker. Although preparation of these types of conjugates has been published, desmosine and isodesmosine used by researchers are obtained from natural sources such as animal tissues. Here, we report the first synthetic preparation of isodesmosine and keyhole limpet hemocyanin (KLH) conjugate from commercially available chiral amino acids and carrier protein. Formation of the core pyridinium of isodesmosine was achieved through key reaction-Chichibabin pyridinium synthesis-to deliver a 1,2,3,5-tetrasubstituted pyridinium amino acid selectively. Further modifications involving KLH and maleimide linker provided the target conjugate, which could potentially invoke an immune response to produce anti-isodesmosine antibody for the ELISA system.

Mediator lipidomics in ophthalmology: targets for modulation in inflammation, neuroprotection and nerve regeneration

Studies in the central nervous system (CNS) and retina have revealed the significance of docosahexaenoic acid (DHA), an essential omega-3, 22 carbon 6 double bond (22:6), fatty acid. DHA is necessary for various functions in the CNS, including neuronal membrane bio- and synaptogenesis in memory and vision, and it is the precursor for docosanoids and neuroprotectin D1 (NPD1; 10R,17S-dihydroxy-docosa-4Z,7Z,11E,13E,15Z,19Z hexaenoic acid), a DHA bio-derivative with neuroprotective properties. This review covers three targets in ophthalmology for mediator lipidomics, a subgroup within the field of metabolomics: inflammation, neuroprotection and nerve regeneration. It also discusses the role DHA, NPD1 and other lipid mediators play in these three areas.

High-resolution ultra-high mass spectrometry: increasing the m/z range of protein analysis

The proof of principle for high-resolution TOF mass analysis spanning the entire range of intact singly charged proteins has recently been demonstrated. The centers of the isotope distributions of individual proteins in a complex distribution can be defined to within 0.5 Da or better up to 200 kDa with internal calibration. This achievement will have an enormous effect on the process of routine protein analysis over the next few years as the technology mainstreams. The greatest obstacle to high-resolution in the ultra-high mass range (m/z > 20 000) is the expansion-induced kinetic energy (KE) and its spread. The solution to this problem is to trap the ions in a buffer gas so that the motion of the ions can be completely defined by the applied fields. If this can accomplished without mass dependence, then any ion, regardless of size, can be mass analyzed with high resolution. This article discusses the methodology that we used to capture atmosphere sampled singly charged proteins in vacuum at a point just before they enter the mass analyzer to completely eliminate the expansion-induced KE. We then used digitally created quadrupole waveforms to inject the ions into the mass analyzer in a well-collimated plug with a controlled amount of KE. Trapping the ions to remove the expansion-induced KE and then electrodynamically manipulating the ions are the key steps to high-resolution mass analysis at any value of m/z. The impact of this technology will be discussed.

Research resource: nuclear receptor atlas of human retinal pigment epithelial cells: potential relevance to age-related macular degeneration

Retinal pigment epithelial (RPE) cells play a vital role in retinal physiology by forming the outer blood-retina barrier and supporting photoreceptor function. Retinopathies including age-related macular degeneration (AMD) involve physiological and pathological changes in the epithelium, severely impairing the retina and effecting vision. Nuclear receptors (NRs), including peroxisome proliferator-activated receptor and liver X receptor, have been identified as key regulators of physiological pathways such as lipid metabolic dysregulation and inflammation, pathways that may also be involved in development of AMD. However, the expression levels of NRs in RPE cells have yet to be systematically surveyed. Furthermore, cell culture lines are widely used to study the biology of RPE cells, without knowledge of the differences or similarities in NR expression and activity between these in vitro models and in vivo RPE. Using quantitative real-time PCR, we assessed the expression patterns of all 48 members of the NR family plus aryl hydrocarbon receptor and aryl hydrocarbon receptor nuclear translocator in human RPE cells. We profiled freshly isolated cells from donor eyes (in vivo), a spontaneously arising human cell line (in vitro), and primary cell culture lines (in vitro) to determine the extent to which NR expression in the cultured cell lines reflects that of in vivo. To evaluate the validity of using cell culture models for investigating NR receptor biology, we determined transcriptional activity and target gene expression of several moderately and highly expressed NRs in vitro. Finally, we identified a subset of NRs that may play an important role in pathobiology of AMD.

Characterization of protein release from hydrolytically degradable poly(ethylene glycol) hydrogels

We present a novel fully hydrophilic, hydrolytically degradable poly(ethylene glycol) (PEG) hydrogel suitable for soft tissue engineering and delivery of protein drugs. The gels were designed to overcome drawbacks associated with current PEG hydrogels (i.e., reaction mechanisms or degradation products that compromise protein stability): the highly selective and mild cross-linking reaction allowed for encapsulating proteins prior to gelation without altering their secondary structure as shown by circular dichroism experiments. Further, hydrogel degradation and structure, represented by mesh size, were correlated to protein release. It was determined that polymer density had the most profound effect on protein diffusivity, followed by the polymer molecular weight, and finally by the specific chemical structure of the cross-linker. By examining the diffusion of several model proteins, we confirmed that the protein diffusivity was dependent on protein size as smaller proteins (e.g., lysozyme) diffused faster than larger proteins (e.g., Ig). Furthermore, we demonstrated that the protein physical state was preserved upon encapsulation and subsequent release from the PEG hydrogels and contained negligible aggregation or protein-polymer adducts. These initial studies indicate that the developed PEG hydrogels are suitable for release of stable proteins in drug delivery and tissue engineering applications.