Predicting undergraduates' self-reported engagement in traditional and cyberbullying from attitudes.

Studies indicate that attitudes predict traditional forms of bullying. Fewer studies have tested this for cyberbullying, in which the harassment is delivered via electronic communication technology. The current study represents the first direct comparison of attitudes toward the two forms of bullying among undergraduates (N=405). It also tested the hypothesis that engagement in traditional and cyberbullying could be predicted from attitudes toward bullying behavior, bullies, and victims. Results indicated that participants held least favorable attitudes toward physical bullying/bullies, more accepting attitudes toward verbal bullying/bullies, and attitudes toward forms of cyberbullying/bullies somewhere in between. Significant sex differences were also obtained; women expressed significantly less accepting attitudes toward bullying behavior and perpetrators, and more accepting attitudes toward victims, across all subtypes of bullying. The hypothesis that attitudes predict bullying behavior received some support. Some similarities and differences emerged for cyber and traditional forms. The implications for future research, theory building, and interventions are discussed.

A role for Notch signaling in corneal wound healing.

To identify the role of the Notch signaling pathway in corneal wound healing, rat corneas receiving either epithelial or stromal wounds were placed in organ culture for up to 3 and 14 days, respectively. Localization of Notch receptors--Notch1, Notch2, and their ligands--Delta1, Jagged1 was determined by immunofluorescence. Wounds were treated with a γ-secretase inhibitor to suppress Notch signaling or recombinant Jagged1 to enhance Notch signaling and morphological changes in the epithelium and stroma were recorded. The expressions of markers of cell proliferation (Ki67) and epithelial differentiation (cytokeratin 3) were assessed by immunohistology. Notch1 and Notch2 were localized to suprabasal epithelial cells in normal corneas. During corneal wound healing, both Notch receptors were detected in suprabasal and superficial epithelial layers. Delta1 and Jagged1 were observed throughout all corneal epithelial cell layers and occasional keratocytes of the stroma in normal and wounded corneas. γ-secretase inhibition of Notch resulted in increased epithelial cell layers, with recombinant Jagged1 activation of Notch leading to a reduction in epithelial cell layers during corneal wound healing. Correspondingly, the activation of Notch resulted in a decreased cytokeratin 3 expression in the corneal epithelium, with no effect on cellular expression of Ki67. Notch signaling pathway suppressed corneal epithelial differentiation during corneal wound healing, but had no effect on epithelial cell proliferation.

Apoptosis gene profiling reveals spatio-temporal regulated expression of the p53/Mdm2 pathway during lens development.

Evidence is emerging for apoptosis gene expression in the lens during development. Therefore, here we used a filter array to assess expression of 243 apoptosis-related genes in the developing postnatal mouse lens using (33)P labelled cDNA synthesized from p7 and p14 mouse lenses. We demonstrated that 161 apoptosis-related genes were expressed at levels significantly above background and 20 genes were potentially significantly differentially expressed (P<0.05) by at least 2-fold between p7 and p14. We used RT-PCR to confirm expression of these genes in newborn, p7, p14 and 4 wk mouse lens cDNA samples. Expression of 19/20 of the genes examined was confirmed, while 5 genes (Huntingtin, Mdm2, Dffa, galectin-3 and Mcl-1) were confirmed as differentially regulated between p7 and p14. RT-PCR was also used to examine the expression of the chick homologues of the most-highly expressed and/or potentially differentially regulated genes in chick embryo lenses at E6-E16. The majority of genes expressed in the postnatal mouse lens were also expressed in the chick embryo lens. Western blotting confirmed developmentally regulated expression of Axl and Mcl-1 during mouse lens development and of Mdm2, Mdm4/X and p53 during mouse and chick lens development. Western blotting also revealed the presence of p53 and Mdm4/X splice variants and/or proteolytic cleavage products in the developing lens. Since Mdm2 is a regulator of the tumour suppressor gene p53, we chose to thoroughly investigate the spatio-temporal expression patterns of p53, Mdm2 and the functionally related Mdm4/X in mouse lens development at E12.5-E16.5 using immunocytochemistry. We also examined Mdm2 expression patterns during chick lens development at E6-E16 and Mdm4/X and p53 at E14. Expression of Mdm2, Mdm4/X and p53 was spatio-temporally regulated in various compartments of the developing lens in both mouse and chick, including lens epithelial and lens fibre cells, indicating potential roles for these factors in regulation of lens epithelial cell proliferation and/or lens fibre cell differentiation This study provides a thorough initial analysis of apoptosis gene expression in the postnatal mouse lens and provides a resource for further investigation of the roles in lens development of the apoptosis genes identified. Furthermore, building on the array studies, we present the first spatio-temporal analysis of expression of p53 pathway molecules (p53, Mdm2 and Mdm4/X) in both developing mouse and chick lenses, suggesting a potential role for the p53/Mdm2 pathway in lens development, which merits further functional analysis.

Tear sample collection using cellulose acetate absorbent filters.

PURPOSE: To assess the use of cellulose acetate filter rods as a technique for tear collection. METHOD: The cellulose acetate rod (CR) was compared with the 'standard' glass capillary tube (CT), in a series of experiments, to assess: sample collection by collected volume size; the effect of tear stimulation on total tear protein concentration and major tear protein concentrations; and technique invasiveness. RESULTS: No difference was found in concentrations for total protein, IgA (secretory immunoglobulin A), lactoferrin and lysozyme (p > 0.05) with no clinically significant increase in serum albumin to show serum leakage. Sample volume was higher for CR (p < 0.005) and sample volume increased for stimulated collection with CR (p = 0.001). Dilution effect of a stimulated sample size was reliably shown only with CR (r = -0.66, p = 0.011). Using bovine albumin standard with CR and CT, a smaller sample volume (p < 0.001) and a higher protein concentration (p < 0.001) were extracted with CR. CONCLUSION: The cellulose rod offers a suitable alternative to the glass CT. It is able to quickly absorb a sample, allowing use for a wide range of sample sizes, while being minimally invasive.

Carbomer and sodium hyaluronate eyedrops for moderate dry eye treatment.

PURPOSE: This randomized, double-masked study compared the effectiveness of two commercially available ocular lubricants containing either 0.3% Carbomer 934 or 0.18% sodium hyaluronate (SH) in treating moderate dry eye. METHODS: Sixty-five subjects with dry eye were recruited and supplied with eyedrops containing either Carbomer or SH to use for a month. Principle outcome measures were the severity of symptoms of ocular irritation, tear break-up time without (NIBUT) and with (TBUT) fluorescein, and corneal and conjunctival staining with fluorescein and lissamine green, respectively. At the end of the experiment, subjects were also asked, on average, how many times a day they used the treatment and the duration of any post-instillation blur. RESULTS: Both Carbomer and SH reduced the symptom severity and ocular surface staining, but neither had a lasting effect on NIBUT or TBUT. The treatment effects of Carbomer and SH were equivalent for symptoms, NIBUT and TBUT. However, for both corneal and conjunctival staining, SH outperformed Carbomer in improving the integrity of the ocular surface. There was no difference in the average instillation frequency of the two products. Visual disturbance after instillation of either formulation was generally short, but lengthy periods of blur were significantly more common after the use of Carbomer. CONCLUSIONS: Both of the eyedrops trialled are suitable for patients with moderate dry eye, but of the two, the SH-containing treatment has marginal benefits in therapeutic efficacy and has less propensity to cause visual disturbance.

A role for notch signaling in human corneal epithelial cell differentiation and proliferation.

PURPOSE: To identify the role of Notch signaling in the human corneal epithelium. METHODS: Localization of Notch1, Notch2, Delta1, and Jagged1 in the human corneal epithelium was observed with the use of indirect immunofluorescence microscopy. Gene and protein expression of Notch receptors and ligands in human corneal epithelial cells was determined by RT-PCR and Western blot analysis, respectively. The effects of Notch inhibition (by gamma-secretase inhibition) and activation (by recombinant Jagged1) on epithelial cell proliferation (Ki67) and differentiation (CK3) were analyzed after Western blotting and immunocytochemistry. RESULTS: Immunofluorescent labeling localized Notch1 and Notch2 to suprabasal epithelial cell layers, whereas Delta1 and Jagged1 were observed throughout the corneal epithelium. Notch1, Notch2, Delta1, and Jagged1 genes and proteins were expressed in human corneal epithelial cells. gamma-Secretase inhibition resulted in decreased Notch1 and Notch2 expression, with an accompanying decrease in Ki67 and increased CK3 expression. The activation of Notch by Jagged1 resulted in the upregulation of active forms of Notch1 and 2 proteins (P < 0.05), with a concurrent increase in Ki67 (P < 0.05) and a decrease in CK3 (P < 0.05) expression. Interestingly, gamma-secretase inhibition in a three-dimensional, stratified corneal epithelium equivalent had no effect on Ki67 or CK3 expression. In contrast, Jagged1 activation resulted in decreased CK3 expression (P < 0.05), though neither Notch activation nor inhibition affected cell proliferation in the 3D tissue equivalent. CONCLUSIONS: Notch family members and ligands are expressed in the human corneal epithelium and appear to play pivotal roles in corneal epithelial cell differentiation.

L-carnitine protects human retinal pigment epithelial cells from oxidative damage.

PURPOSE: To determine the efficacy of L-carnitine (LC) against oxidative changes in human retinal pigment epithelium (RPE) cells. METHODS: The RPE cells from human donor eyes were cultured in Hams F-10 medium. The effect of LC on H2O2-induced morphologic changes in the RPE cells was analyzed by light microscopy. Reduction in cell death after the impact of LC treatment on H2O2-treated cells was analyzed by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays. In addition, the effect of H2O2 on the activity of RPE-antioxidant enzymes, glutathione (GSH) and superoxide dismutase (SOD), and LC-induced protection was also determined. RESULTS: LC protected the RPE cells by inhibiting the peroxide-induced cytopathic effect from 50% to 10%. Nuclear condensation observed in 40% of the H2O2-treated cells decreased to 20% after LC treatment. The MTT assays demonstrated that 100 microM oxidant caused appreciable cell death, which was reduced by LC treatment; however, 100% protection was not achieved. Significant peroxide-induced cell death was seen within 5 hr of H2O2 treatment, and a quantifiable reduction was observed after LC treatment for a similar time period. The change in the antioxidant potential of the RPE induced by oxidative stress was restored by LC treatment, as demonstrated by an increase in GSH and SOD activities. CONCLUSIONS: LC is capable of protecting the RPE cells from H2O2-induced oxidative damage, implying that micronutrients can have a positive effect and can play an important role in the treatment of oxidation-induced ocular disorders. Further studies are needed to understand the mechanism of LC-induced protection to the RPE cells.

Confocal Raman microscopy can quantify advanced glycation end product (AGE) modifications in Bruch's membrane leading to accurate, nondestructive prediction of ocular aging.

The modification of proteins by nonenzymatic glycation leading to accumulation of advanced glycation end products (AGEs) is a well-established phenomenon of aging. In the eyes of elderly patients, these adducts have been observed in retinal pigment epithelium (RPE), particularly within the underlying pentalaminar substrate known as Bruch's membrane. AGEs have also been localized to age-related subcellular deposits (drusen and basal laminar deposits) and are thought to play a pathogenic role in progression of the major sight-threatening condition known as age-related macular degeneration (AMD). The current study has quantified AGEs in Bruch's membrane from postmortem eyes and established age-related correlations. In particular, we investigated the potential of confocal Raman microscopy to identify and quantify AGEs in Bruch's membrane in a nondestructive, analytical fashion. Bruch's membrane and the innermost layers of the underlying choroid (BM-Ch) were dissected from fresh postmortem eye-cups (n=56). AGE adducts were quantified from homogenized tissue using reverse-phase HPLC and GC/MS in combination with immunohistochemistry. For parallel Raman analysis, BM-Ch was flat-mounted on slides and evaluated using a Raman confocal microscope and spectra analyzed by a range of statistical approaches. Quantitative analysis showed that the AGEs pentosidine, carboxymethyllysine (CML), and carboxyethyllysine (CEL) occurred at significantly higher levels in BM-Ch with age (P<0.05-0.01). Defined Raman spectral "fingerprints" were identified for various AGEs and these were observed in the clinical samples using confocal Raman microscopy. The Raman data set successfully modeled AGEs and not only provided quantitative data that compared with conventional analytical approaches, but also provided new and complementary information via a nondestructive approach with high spatial resolution. It was shown that the Raman approach could be used to predict chronological age of the clinical samples (P<0.001) and a difference in the Raman spectra between genders was highly significant (P<0.000001). With further development, this Raman-based approach has the potential for noninvasive examination of AGE adducts in living eyes and ultimately to assess their precise pathogenic role in age-related diseases.

Connective tissue structure of the tree shrew optic nerve and associated ageing changes.

PURPOSE: To identify the structure and composition of the tree shrew optic nerve to determine its potential as a model for glaucoma. METHODS: Tree shrew optic nerves, aged 4 weeks to 5 years, were wax or cryoembedded for analysis of overall morphology and cellular (glial fibrillary acidic protein [GFAP]) and extracellular matrix (collagen types I, III, IV, V, VI; fibronectin; and elastin) immunolocalization studies. In addition, transmission and scanning electron microscopy were performed. In vivo optic disc imaging was performed by HRT2 and fundus camera photography. RESULTS: The optic nerve of the tree shrew comprised regions comparable to the human prelaminar and lamina cribrosa (LC) in the optic nerve head and the retrolaminar region, immediately posterior. The multilayered connective tissue plates of tree shrew LC stretched across the optic nerve canal at the level of the sclera and consisted of collagen types I, III, IV, V, and VI; elastin; and fibronectin. Significant age-related alterations in connective tissue components were indicated. Connective tissue was present in the central retinal vessel sheaths and was identified as longitudinally oriented collagen fibrils in the retrolaminar optic nerve. GFAP immunofluorescence indicated a high concentration of astrocytic processes in the LC. Myelination of axons was evident in the retrolaminar optic nerve. Ultrastructural studies supported the structural organization and spatial distribution of connective tissue. CONCLUSIONS: In contrast to many rodent models of glaucoma, since the tree shrew optic nerve resembles that in humans, especially at the LC, the tree shrew offers an ideal opportunity to investigate glaucoma pathophysiology in a subprimate model.

Vascular endothelial growth factor C promotes survival of retinal vascular endothelial cells via vascular endothelial growth factor receptor-2.

AIM: To determine vascular endothelial growth factor C (VEGF-C) expression in retinal endothelial cells, its antiapoptotic potential and its putative role in diabetic retinopathy. METHOD: Cultured retinal endothelial cells and pericytes were exposed to tumour necrosis factor (TNF)alpha and VEGF-C expression determined by reverse transcriptase-polymerase chain reaction. Secreted VEGF-C protein levels in conditioned media from endothelial cells were examined by western blotting analysis. The ability of VEGF-C to prevent apoptosis induced by TNFalpha or hyperglycaemia in endothelial cells was assessed by flow cytometry. The expression of VEGF-C in diabetic retinopathy was studied by immunohistochemistry of retinal tissue. RESULT: VEGF-C was expressed by both vascular endothelial cells and pericytes. TNFalpha up regulated both VEGF-C and vascular endothelial growth factor receptor-2 (VEGFR)-2 expression in endothelial cells in a dose-dependent manner, but had no effect on VEGFR-3. Flow cytometry results showed that VEGF-C prevented endothelial cell apoptosis induced by TNFalpha and hyperglycaemia and that the antiapoptotic effect was mainly via VEGFR-2. In pericytes, the expression of VEGF-C mRNA remained stable on exogenous TNFalpha treatment. VEGF-C immunostaining was increased in retinal vessels in specimens with diabetes compared with retinal specimens from controls without diabetes. CONCLUSION: In retinal endothelial cells, TNFalpha stimulates the expression of VEGF-C, which in turn protects endothelial cells from apoptosis induced by TNFalpha or hyperglycaemia via VEGFR-2 and thus helps sustain retinal neovascularisation.

The contribution of DNA repair and antioxidants in determining cell type-specific resistance to oxidative stress.

The aims of this study were; (i) to elucidate the mechanisms involved in determining cell type-specific responses to oxidative stress and (ii) to test the hypothesis that cell types which are subjected to high oxidative burdens in vivo, have greater oxidative stress resistance. Cultures of the retinal pigment epithelium (RPE), corneal fibroblasts, alveolar type II epithelium and skin epidermal cells were studied. Cellular sensitivity to H2O2 was determined by the MTT assay. Cellular antioxidant status (CuZnSOD, MnSOD, GPX, CAT) was analyzed with enzymatic assays and the susceptibility and repair capacities of nuclear and mitochondrial genomes were assessed by QPCR. Cell type-specific responses to H2O2 were observed. The RPE had the greatest resistance to oxidative stress (P>0.05; compared to all other cell types) followed by the corneal fibroblasts (P < 0.05; compared to skin and lung cells). The oxidative tolerance of the RPE coincided with greater CuZnSOD, GPX and CAT enzymatic activity (P < 0.05; compared to other cells). The RPE and corneal fibroblasts both had up-regulated nDNA repair post-treatment (P < 0.05; compared to all other cells). In summary, variations in the synergistic interplay between enzymatic antioxidants and nDNA repair have important roles in influencing cell type-specific vulnerability to oxidative stress. Furthermore, cells located in highly oxidizing microenvironments appear to have more efficient oxidative defence and repair mechanisms.

Dietary antioxidants provide differential subcellular protection in epithelial cells.

This study aimed to evaluate the organelle-specific antioxidant/pro-oxidant actions of clinically important dietary antioxidants against oxidative stress. An in vitro cellular model was employed to investigate the antioxidant/pro-oxidant effects of various concentrations (1, 10 and 100 microM) of ascorbic acid, alpha-tocopherol and beta-carotene during H2O2-induced oxidative stress. Damage to nuclear and mitochondrial genomes was analyzed by quantitative polymerase chain reaction and oxidation of membrane lipids was measured via colorimetric assays. The key findings were: (i) dietary antioxidants conferred a dose-dependent protective effect (with a pro-oxidant shift at higher concentrations); (ii) the protection conferred to different sub-cellular organelles is highly specific to the dietary antioxidant; (iii) the mtDNA is highly sensitive to oxidative attack compared to nDNA (P < 0.05); and (iv) mtDNA protection conferred by dietary antioxidants was required to improve protection against oxidative-induced cell death. This study shows that antioxidant-induced protection of mtDNA is an important target for future oxidative stress therapies.

Decreased pigment epithelium-derived factor expression in human breast cancer progression.

PURPOSE: The aim of this study was to correlate the expression of pigment epithelium-derived factor (PEDF), a potent endogenous antiangiogenic molecule, with severity and prognosis in breast cancer. EXPERIMENTAL DESIGN: To investigate the gene expression profile of PEDF in human breast cancer in relation to a patient's clinical variables, we examined human breast cancer tissue (n = 119), background breast tissue (n = 33), and a range of cell lines for mRNA and protein levels of PEDF by using reverse transcription PCR, real-time quantitative PCR, immunohistochemistry, and ELISA. RESULTS: By using reverse transcription PCR, real-time quantitative PCR, immunohistochemistry, and ELISA, PEDF expression was found to be dramatically decreased in breast cancer. An overall outlook for the patients inversely correlated with PEDF mRNA levels. Exogenous PEDF inhibits endothelial tubule formation induced by breast cancer cell-conditioned medium, in vitro. CONCLUSION: These observations collectively support the hypothesis that a lack of PEDF expression is a potent factor for the enhancement of tumor growth and angiogenesis in breast cancer.

Differential regulation of key stages in early corneal wound healing by TGF-beta isoforms and their inhibitors.

PURPOSE: Inhibition of TGF-beta reduces myofibroblast differentiation and fibrosis in the cornea. Determining the actions of distinct TGF-beta isoforms and their inhibitors during early corneal wound healing is an essential step in guiding therapeutic intervention. METHODS: Bovine serum-free corneal cell and wounded organ cultures were challenged with a range of concentrations of TGF-beta1, -beta2, and -beta3; IL-10; and neutralizing human monoclonal antibodies (mAbs) against TGF-beta1 (CAT-192) or -beta2, (CAT-152). Cultures were assessed for re-epithelialization, proliferation (cell counts and cresyl violet assay), morphology (histologic examination), repopulation of the area under the wound, and myofibroblast transformation (alpha-smooth muscle actin) between 0 and 5 days. RESULTS: TGF-beta1 delayed re-epithelialization, increased repopulation of the stroma, increased keratocyte proliferation and was the only isoform to promote myofibroblast differentiation. The anti-TGF-beta1 mAb, CAT-192 promoted re-epithelialization and reduced repopulation of the stroma. Exogenous TGF-beta3 had little effect on re-epithelialization but reduced repopulation of the stroma. IL-10 promoted corneal re-epithelialization at low doses but inhibited this response at high doses. Stromal repopulation was prevented by all doses of IL-10. TGF-beta2 or the anti-TGF-beta2 mAb, CAT-152 had little effect on any repair parameter. CONCLUSIONS: The results confirm TGF-beta1 as the principal isoform in corneal wound healing and suggest that inhibition of the action of TGF-beta1 can promote corneal wound healing. Treatment with the anti-TGF-beta1 mAb CAT-192 accelerates corneal re-epithelialization but reduces cell repopulation of the stroma. The cytokines TGF-beta3 and IL-10 have opposing actions to that of TGF-beta1.

Vascular endothelial growth factor-induced endothelial cell proliferation is regulated by interaction between VEGFR-2, SH-PTP1 and eNOS.

VEGF receptor-2 plays a critical role in endothelial cell proliferation during angiogenesis. However, regulation of receptor activity remains incompletely explained. Here, we demonstrate that VEGF stimulates microvascular endothelial cell proliferation in a dose-dependent manner with VEGF-induced proliferation being greatest at 5 and 100 ng/ml and significantly reduced at intermediate concentrations (>50% at 20 ng/ml). Neutralization studies confirmed that signaling occurs via VEGFR-2. In a similar fashion, ERK/MAPK is strongly activated in response to VEGF stimulation as demonstrated by its phosphorylation, but with a decrease in phosphoryation at 20 ng/ml VEGF. Immunoblotting analysis revealed that VEGF did not cause a dose-dependent change in expression of VEGFR-2 but instead resulted in reduced phosphorylation of VEGFR-2 when cells were exposed to 10 and 20 ng/ml of VEGF. VEGFR-2 dephosphorylation was associated with an increase in the protein tyrosine phosphatase, SH-PTP1, and endothelial nitric oxide synthase (eNOS). Immunoprecipitation and selective immunoblotting confirmed the association between VEGFR-2 dephosphorylation and the upregulation of SH-PTP1 and eNOS. Transfection of endothelial cells with antisense oligonucleotide against VEGFR-2 completely abolished VEGF-induced proliferation, whereas anti SH-PTP1 dramatically increased VEGF-induced proliferation by 1 and 5-fold at 10 and 200 ng/ml VEGF, respectively. Suppression of eNOS expression only abolished endothelial cell proliferation at VEGF concentrations above 20 ng/ml. Taken together, these results indicate that activation of VEGFR-2 by VEGF enhances SH-PTP1 activity and eNOS expression, which in turn lead to two diverse events: one is that SH-PTP1 dephosphorylates VEGFR-2 and ERK/MAPK, which weaken VEGF mitogenic activity, and the other is that eNOS increases nitric oxide production which in turn lowers SH-PTP1 activity via S-nitrosylation.

Withdrawal: Pigment epithelium-derived factor inhibits angiogenesis via regulated intracellular proteolysis of vascular endothelial growth factor receptor 1.

Pigment epithelium-derived factor (PEDF) has been identified as one of the most potent of endogenous negative regulators of blood vessel growth in the body. Here we report that PEDF is able to inhibit growth factor-induced angiogenesis in microvascular endothelial cells through a novel pathway requiring cleavage and intracellular translocation of the transmembrane domain of the VEGFR-1. Analysis of the subcellular distribution of VEGFR-1 revealed the appearance of an 80-kDa C-terminal domain in the cytosol of cells treated with VEGF and PEDF that correlated with a decrease of the full-length receptor in the nuclear and cytoskeletal fractions. This regulated intramembrane proteolysis is dependent on gamma-secretase because inhibition of gamma-secretase abolished the inhibitory effect of PEDF on VEGF-induced angiogenesis as well as VEGFR-1 cleavage. The addition of PEDF to microvascular endothelial cells significantly increases gamma-secretase activity even in the absence of VEGF, showing that VEGF binding to VEGF-R1 is essential for substrate availability. This increase in activity was associated with translocation of presenilin 1 from the perinuclear region to the cell membrane. PEDF was also able to inhibit VEGF-induced phosphorylation of VEGFR-1. Taken together we have identified two novel pathways by which PEDF inhibits VEGF-induced angiogenesis: regulated intramembrane proteolysis and inhibition of phosphorylation. This confirms the importance of PEDF and VEGFR-1 in the negative regulation of angiogenesis.

Effectiveness of sodium hyaluronate eyedrops in the treatment of dry eye.

BACKGROUND: Dry eye is a common condition, affecting approximately 10-20% of the adult population. Artificial tears are often effective in relieving symptoms in mild and moderate dry eye by replenishing deficient tear volume. Sodium hyaluronate has been proposed as a component in artificial tears, due to its viscoelastic rheology. This paper reports on a study carried out to assess the efficacy of two recently developed eyedrops containing 0.1% and 0.3% sodium hyaluronate (SH) in the treatment of moderate dry eye. METHODS: Thirteen subjects were recruited with moderate dry eye. Forty microlitres of 0.1% SH, 0.3% SH, or 0.9% saline were instilled in both eyes, and the subjects' symptom intensity and non-invasive break-up time (NIBUT) were measured at 5, 15, 30, 45, and 60 min, and then hourly, until 6 h after drop instillation. This was repeated twice following an interval of 7(+/-1) days, but with a different treatment so that at the end of the final visit each subject had trialled all products. Drop allocation was randomized and double-masked. RESULTS: Both symptoms and NIBUT improved with all treatments. These changes were of a larger magnitude and longer duration with the SH containing eyedrops than with saline. SH of 0.3% tended to perform better than 0.1% SH and achieved statistical significance (P=0.04) for NIBUT when considered over the whole 6-h study period. CONCLUSIONS: Sodium hyaluronate of 0.1% and 0.3% reduces symptoms of ocular irritation and lengthens NIBUT in subjects with moderate dry eye more effectively than saline, in terms of peak effect and duration of action.

Placenta growth factor is over-expressed and has prognostic value in human breast cancer.

Placenta growth factor (PlGF) belongs to the vascular endothelial growth factor (VEGF) family, a group of angiogenic factors that are crucial for tumour angiogenesis. Very little is known about the significance of PlGF in human cancer. We hypothesise that PlGF may have a potent influence in breast cancer. This study examined PlGF levels in human breast cancer in relation to patient's clinical parameters. PlGF expression and distribution was examined quantitatively using real-time quantitative polymerase chain reaction (Q-PCR) on a cohort of human breast cancer tissue (n = 119) and background breast tissue (n = 33), qualitatively using reverse transcriptase polymerase chain reaction (RT-PCR) on a range of cell lines, and immunohistochemically on patient samples. All these techniques revealed that PlGF expression was dramatically increased (P = 0.028) in breast cancer tissues compared with normal breast tissue. We demonstrate that PlGF displays prognostic value through analysis of patient survival status (6-year follow-up), as elevated levels of PlGF were significantly associated (P = 0.017) with recurrence, metastasis and patient mortality. Our study has shown that PlGF is over-expressed in breast cancer tissues and correlates with patient prognosis, and is likely to play a major role in the pathogenesis of tumours.

RPE lipofuscin and its role in retinal pathobiology.

Emerging evidence indicates that the autofluorescent pigments that accumulate as lipofuscin in retinal pigment epithelial (RPE) cells may reach levels that contribute to a decline in cell function. Since recent findings with respect to the origin, composition and adverse effects of RPE lipofuscin have informed our view of this material, the goal of this article is to review our current understanding of these issues.

Antioxidant up-regulation and increased nuclear DNA protection play key roles in adaptation to oxidative stress in epithelial cells.

Cells are armed with a vast repertoire of antioxidant defense mechanisms to help prevent the accumulation of oxidative damage. It is becoming increasingly apparent that the cellular adaptive response has an important antioxidant function to counteract oxidative stress. To investigate this adaptive response we assessed the effect of sublethal H2O2 on cell viability, enzymatic activity, and nuclear (nDNA) and mitochondrial DNA (mtDNA) susceptibility to damage and repair in cultured human retinal pigment epithelium (RPE) cells. This nondividing cell type exists in a highly oxidizing microenvironment in vivo. Prior exposure to sublethal H2O2 confirmed an adaptive response, resulting in a greater cellular resistance to subsequent toxic exposures compared to nonadapted RPE (p < 0.05). A greater CAT, GPX, and CuZnSOD enzymatic activity (p < 0.05) and increased nDNA protection (p < 0.05) were also observed. However, there was no adaptive benefit for mtDNA protection or repair in response to oxidative stress. This study confirms a role for the adaptive response as an important antioxidant defense for cells located in inherently oxidizing microenvironments. Furthermore, it identifies that the mitochondria are a weak link in otherwise efficient oxidative stress defenses and that this may contribute to aging and age-related disease.