Semi-synthesis and antiproliferative evaluation of PEGylated pentacyclic triterpenes.

Several PEGylated derivatives of oleanolic and maslinic acids have been semi-synthesized, attaching one acid-PEG reagent to the hydroxyl group/s at C-2 or C-2/C-3 of the A rings of these natural triterpenes, and also to their corresponding C-28 benzyl derivatives. Several monomeric and dimeric PEGylated compounds have also been produced by linking one diamine-PEG reagent to the carboxyl group at C-28 of the same natural triterpenes and also to their corresponding C-2 or C-2/C-3 acetylated derivatives. The cytotoxic effects of 12 triterpenic PEGylated derivatives in three cancer-cell lines (B16F10, HT29, and Hep G2) have been assayed.

Microglial Activation Promotes Cell Survival in Organotypic Cultures of Postnatal Mouse Retinal Explants.

The role of microglia during neurodegeneration remains controversial. We investigated whether microglial cells have a neurotoxic or neuroprotective function in the retina. Retinal explants from 10-day-old mice were treated in vitro with minocycline to inhibit microglial activation, with LPS to increase microglial activation, or with liposomes loaded with clodronate (Lip-Clo) to deplete microglial cells.

DNA damage, poly(ADP-Ribose) polymerase activation, and phosphorylated histone H2AX expression during postnatal retina development in C57BL/6 mouse.

Purpose: The purpose of this study was to investigate the incidence of DNA damage during postnatal development of the retina and the relationship between DNA damage and cell death.

Methods: DNA damage in the developing postnatal retina of C57BL/6 mice was assessed by determining the amounts of 8-hydroxy-2'-deoxyguanosine (8-OHdG), which is indicative of DNA oxidation and related to the formation of DNA single-strand breaks (SSBs), and phosphorylated histone H2AX (γ-H2AX), a marker of DNA double-strand breaks (DSBs). Poly(ADP-ribose) polymerase (PARP) activation was measured by ELISA and Western blotting.

Expression of inducible nitric oxide synthase (iNOS) in microglia of the developing quail retina.

Inducible nitric oxide synthase (iNOS), which produce large amounts of nitric oxide (NO), is induced in macrophages and microglia in response to inflammatory mediators such as LPS and cytokines. Although iNOS is mainly expressed by microglia that become activated in different pathological and experimental situations, it was recently reported that undifferentiated amoeboid microglia can also express iNOS during normal development. The aim of this study was to investigate the pattern of iNOS expression in microglial cells during normal development and after their activation with LPS by using the quail retina as model.

Microglial cells in organotypic cultures of developing and adult mouse retina and their relationship with cell death.

Organotypic cultures of retinal explants allow the detailed analysis of microglial cells in a cellular microenvironment similar to that in the in situ retina, with the advantage of easy experimental manipulation. However, the in vitro culture causes changes in the retinal cytoarchitecture and induces a microglial response that may influence the results of these manipulations. The purpose of this study was to analyze the influence of the retinal age on changes in retinal cytoarchitecture, cell viability and death, and microglial phenotype and distribution throughout the in vitro culture of developing and adult retina explants.

Simultaneous cell death and upregulation of poly(ADP-ribose) polymerase-1 expression in early postnatal mouse retina.

Purpose: Poly(ADP-ribose) polymerase (PARP)-1 is a nuclear enzyme that transfers ADP-ribose units (PAR polymer) to nuclear proteins and has been implicated in caspase-independent cell death in different models of retinal degeneration. The involvement of PARP-1 in cell death occurring during normal postnatal development of the mouse retina was investigated. In addition, the expression of apoptosis-inducing factor (AIF), a caspase-independent cell death mediator, was explored because PARP-1 activation has been related to the translocation of a 57-kDa form of AIF into the cell nucleus.

Migration and ramification of microglia in quail embryo retina organotypic cultures.

Organotypic cultures of retina explants preserve the complex cellular microenvironment of the retina and have been used as a tool to assess the biological functions of some cell types. However, studies to date have shown that microglial cells activate quickly in response to the retina explantation. In this study, microglial cells migrated and ramified in quail embryo retina organotypic cultures (QEROCs) according to chronological patterns bearing a resemblance to those in the retina in situ, despite some differences in cell density and ramification degree.

Microglial response to light-induced photoreceptor degeneration in the mouse retina.

The microglial response elicited by degeneration of retinal photoreceptor cells was characterized in BALB/c mice exposed to bright light for 7 hours and then kept in complete darkness for survival times ranging from 0 hours to 10 days. Photodegeneration resulted in extensive cell death in the retina, mainly in the outer nuclear layer (ONL), where the photoreceptor nuclei are located. Specific immunolabeling of microglial cells with anti-CD11b, anti-CD45, anti-F4/80, anti-SRA, and anti-CD68 antibodies revealed that microglial cells were activated in light-exposed retinas.