Minimally invasive plate osteosynthesis (MIPO) for distal humeral fractures: a cadaveric study and first clinical application.

BACKGROUND: The indication for minimally invasive plate osteosynthesis (MIPO) may include articular fractures depending on the fracture pattern. The goal of this study was to evaluate the feasibility of the MIPO technique for extra- and intra-articular distal humeral fractures. METHODS: The feasibility of the MIPO technique was assessed on 8 cadaveric elbows and 2 clinical cases. The four surgical approaches tested included a 20-mm ulnar incision, a 20-mm dorsoradial incision, and two incisions for olecranon osteotomy (A and B). Surgical incision A was 40 mm on the osteotomy level of the olecranon, and surgical incision B was an extension of the radial incision toward the osteotomy of the olecranon (80 mm). The four approaches were tested on 4 extra-articular (AO 13 A3) fractures and 4 intra-articular (AO 13 C3) fractures. RESULTS: Reduction and plate fixation of all distal humeral fractures (8 cadaveric) with and without osteotomy was feasible. However, when using approach B, the soft tissue tension is reduced due to the wider incision. Nevertheless, both approaches A and B showed the same adequate intra-articular fracture control and reduction. CONCLUSION: The MIPO technique for reduction and plate fixation in distal humeral fractures is feasible. LEVEL OF EVIDENCE: As a feasibility study, this study cannot be clearly classified into a level of evidence. It corresponds most closely to level IV.

Comparison of cytokine/chemokine levels in aqueous humor of primary open-angle glaucoma patients with positive or negative outcome following trabeculectomy.

We aimed to identify differences in cytokine/chemokine levels in the aqueous humor (AH) of primary open-angle glaucoma (POAG) patients who suffered from scarring, compared with POAG patients with no scarring after trabeculectomy surgery. Identification of differently expressed cytokines and chemokines may help to understand scarring and fibrotic processes following trabeculectomy, and to make predictions for the outcome of fistulating surgery in the future. Furthermore, the identification of cell signaling pathways involved in fibrosis offers the opportunity for a more specific antifibrotic therapy with reduced side effects, and an improvement in long-term surgical outcome.Eight samples of AH were collected during trabeculectomy surgery and commercially available cytokine/chemokine arrays were used. Specific, differently expressed proteins (cytokines/chemokines) in AH samples from patients with positive and negative surgery outcomes were detected. These proteins were classified based on their known profibrotic, inflammatory, adhesive, and apoptotic properties. Transforming growth factor ß (TGF-ß) and vascular endothelial growth factor (VEGF) were among the most important profibrotic cytokines that we detected. Differences in the fold change of protein expression were highly significant between patients after successful and failed trabeculectomy surgery, and these were processed and visualized using ExprEssence software.This pilot study revealed differences in concentrations of cytokines/chemokines in AH between the two examined groups of patients. Our findings suggest that a positive outcome from trabeculectomy is strongly related to an inhibition of the fibrosis process.

Osteopontin is induced by TGF-ß2 and regulates metabolic cell activity in cultured human optic nerve head astrocytes.

The aqueous humor (AH) component transforming growth factor (TGF)-ß2 is strongly correlated to primary open-angle glaucoma (POAG), and was shown to up-regulate glaucoma-associated extracellular matrix (ECM) components, members of the ECM degradation system and heat shock proteins (HSP) in primary ocular cells. Here we present osteopontin (OPN) as a new TGF-ß2 responsive factor in cultured human optic nerve head (ONH) astrocytes. Activation was initially demonstrated by Oligo GEArray microarray and confirmed by semiquantitative (sq) RT-PCR, realtime RT-PCR and western blot. Expressions of most prevalent OPN receptors CD44 and integrin receptor subunits αV, α4, α 5, α6, α9, ß1, ß3 and ß5 by ONH astrocytes were shown by sqRT-PCR and immunofluorescence labeling. TGF-ß2 treatment did not affect their expression levels. OPN did not regulate gene expression of described TGF-ß2 targets shown by sqRT-PCR. In MTS-assays, OPN had a time- and dose-dependent stimulating effect on the metabolic activity of ONH astrocytes, whereas TGF-ß2 significantly reduced metabolism. OPN signaling via CD44 mediated a repressive outcome on metabolic activity, whereas signaling via integrin receptors resulted in a pro-metabolic effect. In summary, our findings characterize OPN as a TGF-ß2 responsive factor that is not involved in TGF-ß2 mediated ECM and HSP modulation, but affects the metabolic activity of astrocytes. A potential involvement in a protective response to TGF-ß2 triggered damage is indicated, but requires further investigation.

Topical application of PPADS inhibits complement activation and choroidal neovascularization in a model of age-related macular degeneration.

Age-related macular degeneration (AMD) is the most common cause of blindness among the elderly. AMD patients have elevated levels of membrane attack complex (MAC) in their choroidal blood vessels and retinal pigment epithelium (RPE). MAC forms pores in cell membranes. Low levels of MAC result in an elevation of cytokine release such as vascular endothelial growth factor (VEGF) that promotes the formation of choroidal neovascularization (CNV). High levels of MAC result in cell lysis and RPE degeneration is a hallmark of advanced AMD. The current standard of care for CNV associated with wet AMD is intravitreal injection of anti-VEGF molecules every 4 to 12 weeks. Such injections have significant side effects. Recently, it has been found that membrane pore-forming proteins such as α-haemolysin can mediate their toxic effects through auto- and paracrine signaling and that complement-induced lysis is amplified through ATP release followed by P2X receptor activation. We hypothesized that attenuation of P2X receptor activation may lead to a reduction in MAC deposition and consequent formation of CNV. Hence, in this study we investigated topical application of the purinergic P2X antagonist Pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) as a potential treatment for AMD. We found that 4.17 µM PPADS inhibited formation of HUVEC master junctions and master segments by 74.7%. In a human complement mediated cell lysis assay, 104 µM PPADS enabled almost complete protection of Hepa1c1c7 cells from 1% normal human serum mediated cell lysis. Daily topical application of 4.17 mM PPADS for 3 days attenuated the progression of laser induced CNV in mice by 41.8% and attenuated the deposition of MAC at the site of the laser injury by 19.7%. Our data have implications for the future treatment of AMD and potentially other ocular disorders involving CNV such as angioid streaks, choroidal rupture and high myopia.

Preventive effects of omega-3 and omega-6 Fatty acids on peroxide mediated oxidative stress responses in primary human trabecular meshwork cells.

Pathologic processes in glaucoma include increased apoptosis, accumulation of extracellular material in the trabecular meshwork and optic nerve, condensations of the cytoskeleton and precocious cellular senescence. Oxidative stress was shown to generate these alterations in primary ocular cells. Fatty acids omega-3 and -6 are alleged to constitute a prophylaxis against these deleterious effects. Here, we tested actual preventive effects omega-3 and -6 against peroxide induced stress responses in primary human trabecular meshwork cells. Changes of mitochondrial activity, proliferation, heat shock proteins, extracellular matrix components, and inflammatory markers were evaluated. Alterations of the cytoskeleton were evaluated by phalloidin labeling. Here we report a repressive effect of omega-6 on metabolic activity and proliferation, which was not detected for omega-3. Both agents were able to prevent the anti-proliferative effect of H2O2, but only omega-3 prevented metabolic repression. Expression of heat shock protein 27 was unaltered by both fatty acids, whereas heat shock protein 90 was significantly induced by both. Omega-6 increased fibronectin and connective tissue growth factor synthesis, as well as the amount of secreted fibronectin. Omega-3, instead, induced plasminogen activator inhibitor 1 synthesis. H2O2 further increased fibronectin production in omega-6 supplemented cells, which was not the case in omega-3 treated cells. H2O2 stimulation of plasminogen activator inhibitor 1 and connective tissue growth factor was repressed by both fatty acids. Both fatty acids appeared to abolish H2O2 mediated stimulation of nuclear factor κB and IL-6, but not IL-1α and IL-8. H2O2 induced formation of cross-linked actin networks and stress fibers, which was reduced by preemptive application of omega-3. Omega-6, in contrast, had no protective effect on that, and even seemed to promote condensation. Based on the observed side effects of omega-6, omega-3 appears to be the more beneficial fatty acid in respect of prophylactic intake for prevention of a glaucomatous disease.

Cytokine-dependent ELAM-1 induction and concomitant intraocular pressure regulation in porcine anterior eye perfusion culture.

PURPOSE: To demonstrate the capacity of interleukin (IL)-1 to simultaneously lower intraocular pressure (IOP) and induce trabecular ELAM-1 expression in one experiment and to test for IL-6 accordingly and evaluate the role of transforming growth factor (TGF)-ß2 as an IL-1 antagonist. METHODS: Forty-two porcine eyes were subjected to trabecular meshwork (TM) perfusion with IL-1α, -1ß, or -6 for 48 hours. Twelve of the IL-1α-treated eyes also received TGF-ß2 for the final 24-hour period. Polymerase chain reaction and Western blot analyses of ELAM-1 expression were then performed on harvested TM samples. mRNA regulation of IL-1α, IL-1ß, IL-6, TGF-ß2, and P-selectin (SELP) was determined. RESULTS: IL-1α and -1ß treatment augmented outflow facility approximately threefold while inducing ELAM-1. IL-6 perfusion neither changed IOP nor induced ELAM-1. IL-1α/TGF-ß2 double treatment significantly counteracted the IL-1-induced IOP decrease and markedly reduced the degree of ELAM-1 mRNA upregulation from 22.3- to 3.1-fold, and ELAM-1 protein from 1.9- to 1.2-fold. IL-1α mRNA was upregulated 5.3-, 3.3-, and 5.5-fold after perfusion with IL-1α, -1ß, and -1α/TGF-ß2, respectively. The respective values for IL-6 mRNA were 2.0-, 2.1- and 2.4-fold. Expression of IL-1ß and TGF-ß2 mRNA remained unchanged. IL-6 perfusion had no discernible regulatory effect. CONCLUSIONS: Simultaneous demonstration of IL-1's lowering of IOP and inducing trabecular ELAM-1 was achieved for the first time in one experiment, and its possible implications in the pathogenesis of glaucoma was further emphasized. The involvement of an autocrine feedback loop was confirmed in the porcine system. TGF-ß2 constitutes a potent IL-1 antagonist for IOP and ELAM-1 regulation.

Expression of podoplanin and other lymphatic markers in the human anterior eye segment.

PURPOSE: To investigate the expression of lymphatic endothelial cell (LEC) markers in tissues of the anterior eye segment. METHODS: Sections of human anterior segments from eight eyes of eight donors (37-100 years) were stained for Vegf-R3, Prox-1, Lyve-1, Pdpn, Pcx, CCR7, Ccl19, Ccl21, and CD68. Pdpn localization was additionally analyzed by immunogold labeling on sections of five eyes. Expression of LEC markers and chemokine receptor/ligands was analyzed by RT-PCR in iris and trabecular meshwork (TM) tissue from three eyes and eight human TM (hTM) cell cultures. RESULTS: Vegf-R3 and Prox-1 stained no structures in the anterior segment. Lyve-1 stained single dendriform cells in the ciliary body, the TM, and the iris. Pdpn stained all trabecular cells, the cells of the trabeculum ciliare, and the anteriormost perimysium cells of the ciliary muscle. Schlemm's canal endothelium was not stained but reacted to a podocalyxin antibody. In the iris stroma, single dendriform cells were stained; at the anterior surface, almost all cells were Pdpn(+). Few stromal cells were Pdpn(+)/Lyve(+), but several anterior surface cells were Pdpn(+)/Ccl21(+). Solitary CCR7(+) cells were observed there, too. IF results were confirmed by PCR, but Prox-1 was detected in TM and iris. Cultured hTM cells displayed partial Pdpn/Ccl21 colocalization. CONCLUSIONS: Coexpression of Pdpn and Ccl21 at the anterior iris surface and in the chamber angle suggests the constitution of a chemokine gradient guiding APCs through the anterior chamber. The more pronounced expression of Pdpn in the TM could favor egression of APCs by way of the conventional outflow.

Changes of osteopontin in the aqueous humor of the DBA2/J glaucoma model correlated with optic nerve and RGC degenerations.

PURPOSE: To identify age-dependent regulated aqueous humor (AH) factors in DBA2/J (D2J) mice and to correlate them with optic nerve degeneration and intraocular pressure (IOP) by population and individual analysis. METHODS: AH samples of D2J mice aged 2 (n = 3), 7 (n = 5), and 10 months (n = 14) were analyzed by mouse cytokine antibody array. Ten-month samples were classified into eyes with (D2J+) or without (D2J-) optic neuropathy. Ten-month-old C57/Bl6 (B6; n = 13) and DBA2/Rj (D2Rj; n = 15) mice served as controls. IOP was recorded from 2 to 10 months. Individual AH osteopontin (OPN) was determined in 31 D2J eyes (10 months) and was correlated with optic neuropathy and IOP. OPN mRNA was detected by in situ hybridization. OPN blood plasma content of D2J and B6 was monitored from 8 to 10 months. Effect of OPN on cell survival in the ganglion cell layer (GCL) or metabolism was tested in ex vivo-cultured D2Rj eyes and murine neuronal precursors. RESULTS: In array analysis, OPN was detected in 10-month-old D2J mice only. They significantly differed between D2J- and D2J+ (P = 0.006). By Western blot analysis, a sevenfold OPN increase in D2J+ was determined compared with B6. Individual analysis confirmed the positive correlation of OPN with optic neuropathy. IOP was not correlated with OPN. OPN blood plasma contents steadily increased with age in D2J. OPN(+) cells were detected within the ciliary body of D2J, and OPN(+) RGCs were ≈30% reduced. OPN treatment inhibited cell degeneration within the GCL in ex vivo-cultured D2Rj eyes and increased the metabolic activity of neuronal precursor cells. CONCLUSIONS: OPN is an age-dependent increased AH factor associated with degeneration of the optic nerve in D2J mice. By modulating the metabolism of neuronal cells, deregulated levels of OPN could be involved in degenerative processes affecting RGCs or optic nerve axons in the D2J model.