Analytical model of friction at low shear rates for soft materials in 3D printing.

BACKGROUND: The biological properties of silicone elastomers such as polydimethylsiloxane (PDMS) have widespread use in biomedicine for soft tissue implants, contact lenses, soft robots, and many other small medical devices, due to its exceptional biocompatibility. Additive manufacturing of soft materials still has significant challenges even with major advancements that have occurred in development of these technologies for customized medical devices and tissue engineering. OBJECTIVE: The aim of this study was to develop a mathematical model of tangential stress in relation to shear stress, shear rate, 3D printing pressure and velocity, for non-Newtonian gels and fluids that are used as materials for 3D printing. METHOD: This study used FENE (finitely extensible nonlinear elastic model) model, for non-Newtonian gels and fluids to define the dependences between tangential stress, velocity, and pressure, considering viscosity, shear stress and shear rates as governing factors in soft materials friction and adhesion. Experimental samples were fabricated as showcases, by SLA and FDM 3D printing technologies: elastic polymer samples with properties resembling elastic properties of PDMS and thermoplastic polyurethane (TPU) samples. Experimental 3D printing parameters were used in the developed analytical solution to analyse the relationships between governing influential factors (tangential stress, printing pressure, printing speed, shear rate and friction coefficient). Maple software was used for numerical modelling. RESULTS: Analytical model applied on a printed elastic polymer, at low shear rates, exhibited numerical values of tangential stress of 0.208-0.216 N m - 2 at printing velocities of 0.9 to 1.2 mm s - 1, while the coefficient of friction was as low as 0.09-0.16. These values were in accordance with experimental data in literature. Printing pressure did not significantly influence tangential stress, whereas it was slightly influenced by shear rate changes. Friction coefficient linearly increased with tangential stress. CONCLUSION: Simple analytical model of friction for elastic polymer in SLA 3D printing showed good correspondence with experimental literature data for low shear rates, thus indicating possibility to use it for prediction of printing parameters towards desired dimensional accuracy of printed objects. Further development of this analytical model should enable other shear rate regimes, as well as additional soft materials and printing parameters.

MDE and LLM Synergy for Network Experimentation: Case Analysis of Wireless System Performance in Beaulieu-Xie Fading and κ-µ Co-Channel Interference Environment with Diversity Combining.

Channel modeling is a first step towards the successful projecting of any wireless communication system. Hence, in this paper, we analyze the performance at the output of a multi-branch selection combining (SC) diversity receiver in a wireless environment that has been distracted by fading and co-channel interference (CCI), whereby the fading is modelled by newer Beaulieu-Xie (BX) distribution, and the CCI is modelled by the κ-µ distribution. The BX distribution provides the ability to include in consideration any number of line-of-sight (LOS) useful signal components and non-LOS (NLOS) useful signal components. This distribution contains characteristics of some other fading models thanks to its flexible fading parameters, which also applies to the κ-µ distribution. We derived here the expressions for the probability density function (PDF) and cumulative distribution function (CDF) for the output signal-to-co-channel interference ratio (SIR). After that, other performances are obtained, namely: outage probability (Pout), channel capacity (CC), moment-generating function (MGF), average bit error probability (ABEP), level crossing rate (LCR), and average fade duration (AFD). Numerical results are presented in several graphs versus the SIR for different values of fading and CCI parameters, as well as the number of input branches in the SC receiver. Then, the impact of parameters on all performance is checked. From our numerical results, it is possible to directly obtain the performance for all derived and displayed quantities for cases of previously known distributions of fading and CCI by inserting the appropriate parameter values. In the second part of the paper, a workflow for automated network experimentation relying on the synergy of Large Language Models (LLMs) and model-driven engineering (MDE) is presented, while the previously derived expressions are used for evaluation. Due to the aforementioned, the biggest value of the obtained results is the applicability to the cases of a large number of other distributions for fading and CCI by replacing the corresponding parameters in the formulas for the respective performances.

Effects of Limiting the Number of Different Cross-Sections Used in Statically Loaded Truss Sizing and Shape Optimization.

This research aims to show the effects of adding cardinality constraints to limit the number of different cross-sections used in simultaneous sizing and shape optimization of truss structures. The optimal solutions for sizing and shape optimized trusses result in a generally high, and impractical, number of different cross-sections being used. This paper presents the influence of constraining the number of different cross-sections used on the optimal results to bring the scientific results closer to the applicable results. The savings achieved using the cardinality constraint are expected to manifest in more than just the minimization of weight but in all the other aspects of truss construction, such as labor, assembly time, total weld length, surface area to be treated, transport, logistics, and so on. It is expected that the optimal weight of the structures would be greater than when not using this constraint; however, it would still be below conventionally sized structures and have the added benefits derived from the simplicity and elegance of the solution. The results of standard test examples for each different cardinality constraint value are shown and compared to the same examples using only a single cross-section on all bars and the overall optimal solution, which does not have the cardinality constraint. An additional comparison is made with results of just the sizing optimization from previously published research where authors first used the same cardinality constraint.

Combined Treatment of Persistent Diabetic Macular Edema with Aflibercept and Triamcinolone Acetonide in Pseudophakic Eyes.

Background and Objectives: The main cause of the vision loss in diabetics is the development of diabetic macular edema, regardless of the stage of diabetic retinopathy. The paper aimed to examine whether the additional intravitreal application of triamcinolone acetonide to continuous anti-vascular endothelial growth factor therapy could improve therapeutic outcomes for pseudophakic eyes with persistent diabetic macular edema. Materials and Methods: twenty-four pseudophakic eyes with refractory diabetic macular edema, that had appeared despite three previously administered intravitreal injections of aflibercept, were divided into two groups (twelve eyes in each group). The first group continued to have aflibercept administered according to a fixed dosing regimen (once in two months). Triamcinolone acetonide 10 mg/0.1 mL (administered once per four months) was included for the second group, i.e., their treatment continued with a combination of aflibercept + triamcinolone acetonide. Results: The reduction in central macular thickness was higher in the eyes treated with combined therapy (aflibercept + triamcinolone acetonide) compared with the use of aflibercept alone during the entire 12-month follow-up period (3rd month p = 0.019; 6th month p = 0.023; 9th month p = 0.027; 12th month p = 0.031). As was evident from the p-values, the differences were statistically significant. No statistically significant difference was recorded for visual acuity: 3rd month p = 0.423; 6th month p = 0.392; 9th month p = 0.413; 12th month p = 0.418. Conclusions: Combined anti-vascular endothelial growth factor and steroid therapy leads to a better anatomical outcome of persistent diabetic macular edema in pseudophakic eyes, but does not lead to a more significant improvement in visual acuity than continuous anti-VEGF therapy alone.

Multidisciplinary speech and language therapy approach in a child with multiple disabilities including blindness due to retinopathy of prematurity: a case study with a one year follow-up.

Aim: This study aims to show speech and language, sensory-motor, and emotional progress after one year of therapy according to the needs of and resources for a child with multiple disabilities and blindness due to retinopathy of prematurity (ROP).Methods: A 45-month-old boy was examined by a multidisciplinary team and assessed using the Sensory Profile 2, The Vineland Adaptive Behavior Scale II, The Communication Matrix, and The Scale for Evaluation of Psychophysiological Abilities of Children Aged 0-7. After a year of daily individually adopted speech and language therapy followed by supplementary therapeutics method, based on a multidisciplinary approach, the child was reassessed using the same battery of tests.Results: The obtained results might indicate the importance of factors such as a multidisciplinary approach, individualization, communication pathways, therapist's characteristics, and trust when working with children with multiple disabilities.Conclusion: Taking into account all the features of multiple disabilities during the treatment course, continuous monitoring, modification, and adaptation of applied therapy method proved successful in this case.

IS A DECREASED NITRIC OXIDE CONCENTRATION AFTER TRIAMCINOLONE ACETONIDE INTRAVITREAL INJECTION ONE OF THE REASONS FOR INTRAOCULAR PRESSURE RISE?

Diabetic macular edema is the most common cause of vision loss in patients affected by diabetes mellitus. For eyes with persistent retinal thickening despite anti-VEGF therapy, treatment with intravitreal triamcinolone may be considered, especially in pseudophakic eyes. The aim of this study was to examine aqueous humor nitric oxide concentration changes in pseudophakic eyes with persistent diffuse diabetic macular edema after intravitreal injection of triamcinolone acetonide, as well as the potential impact of these changes on the intraocular pressure values. In 10 pseudophakic eyes with persistent diffuse diabetic macular edema, paracentesis of anterior chamber with aspiration of aqueous humor and nitric oxide concentration measurements were done on the day of the intravitreal application of 20 mg triamcinolone acetonide, and after 1, 3, 6 and 9 months. Also, we were recording intraocular pressure values before the intravitreal triamcinolone acetonide injection and during the next 9 months. One month after the intravitreal triamcinolone acetonide injection, we noticed a decrease of nitric oxide concentration (45.37±5.55 µmol/L) by 31.79% compared to the initial values (66.52±7.66 µmol/L). After that, nitric oxide concentrations began to rise slightly, and at the end of the ninth month the mean nitric oxide concentration was similar to that recorded at the beginning of the study. Intraocular pressure values had increasing trend one month after the intravitreal triamcinolone acetonide injection (23.70±4.08 mm Hg) compared to the initial values (16.21±1.55 mm Hg), but after nine months these values returned to normal levels. Decreased concentration of nitric oxide could be one of the reasons for increased intraocular pressure after intravitreal application of triamcinolone acetonide in the treatment of diffuse diabetic macular edema.

THE EFFECT OF PRIMARY ARGON LASER TRABECULOPLASTY ON INTRAOCULAR PRESSURE REDUCTION AND QUALITY OF LIFE IN PATIENTS WITH PSEUDOEXFOLIATION GLAUCOMA.

The aim of the study was to assess the impact of primary argon laser trabeculoplasty (ALT) on intraocular pressure (IOP) lowering and quality of life improvement in patients with pseudoexfoliative glaucoma. Sixty patients with newly diagnosed pseudoexfoliative glaucoma who underwent primary ALT (group 2) or medication therapy (group 1) were followed-up. The effect of ALT on IOP reduction, dry eye development and number of antiglaucoma drugs used was examined. Patients were examined at the beginning of the study and then after 6, 12, and 18 months. A statistically significant difference between IOP values was observed throughout the 18-month follow-up, with the highest significance recorded 6 months after ALT (p=0.009). Twelve months after the start of the study, the TBUT value was 6.0±0.8 s in group 1 and 8.4±0.7 s in group 2. In group 2, the value of Schirmer test was constantly above 10 millimeters. The number of antiglaucoma medications used in group 1 was statistically significantly higher as compared to group 2 throughout the 18-month study period. ALT was found to be better choice for temporary regulation of IOP in patients with pseudoexfoliative glaucoma.

Treatment of Early Developed Peri-Implantitis in Fibula Graft Site.

The fibula microvascular free flap technique and placement of dental endosseous implants seem to be viable options for reconstructing the mandible, following a resective jaw surgery. The causes of early failures of implants include bone overheating, latent infection by surgical trauma, the factors related with the implant, and overcompression. This case report reviews the mechanisms of early post-implantation bone loss, and suggests the course of treatment for early peri-implantitis for implants that show no mobility. Radiographs and clinical data presented have shown that the surgical treatment of early developed peri-implantitis using GBR methods in free fibula graft sites offers promising and stabile results.

INTRAOCULAR PRESSURE CHANGES AFTER UNEVENTFUL PHACOEMULSIFICATION IN EARLY POSTOPERATIVE PERIOD IN HEALTHY EYES.

The aim was to determine early changes in intraocular pressure (IOP) following uneventful phacoemulsification and intraocular lens (IOL) implantation in healthy eyes. This prospective interventional case series study was conducted at Ophthalmology Department, Kragujevac Clinical Centre, Kragujevac, Serbia. The study included 123 eyes of 123 cataract patients, 66 women and 57 men, age range 50-88 (mean 70.73±7.94) years having undergone phacoemulsification and in-the-bag implantation of a foldable IOL. The patients were treated at Kragujevac Clinical Centre between June 2015 and May 2016. IOP was measured by Goldmann applanation tonometry preoperatively, then 4-6 hours, 18-24 hours and 7 days postoperatively by the same examiner. The mean IOP preoperatively was 15.10±2.68 mm Hg. In three patients, maximum measured IOP was 22 mm Hg. At 4-6 hours postoperatively, the mean IOP was 24.29±7.56 mm Hg (p<0.001), at 18-24 hours it was 18.37±4.80 mm Hg (p<0.001), and 7 days after the surgery the mean IOP was 16.24±2.90 mm Hg (p<0.05). The measured IOP values were statistically significant in all measured times. However, at 4-6 hours and 18-24 hours, the mean IOP value was highly statistically significant (p<0.001). Although 7 days after the surgery IOP normalized, the mean IOP value was statistically significant (p<0.05). In conclusion, our research showed that even eyes with normal preoperative values and uncomplicated phacoemulsification course can show very high IOP values postoperatively, which can cause pain, blurred vision and, rarely, compromise visual function.

Activation of ALDH1A1 in MDA-MB-468 breast cancer cells that over-express CYP2J2 protects against paclitaxel-dependent cell death mediated by reactive oxygen species.

Cytochrome P450 2J2 (CYP2J2) expression is elevated in breast and other tumours, and is known to be protective against cytotoxic agents that may be used in cancer chemotherapy. This study evaluated the mechanisms by which MDA-MB-468 breast cancer cells that stably expressed CYP2J2 (MDA-2J2 cells) were protected against killing by the anti-cancer agent paclitaxel. Compared to control cells caspase-3/7 activation by paclitaxel was lower in MDA-2J2 cells, while cell proliferation and colony formation following paclitaxel treatment were increased. Basal lipid peroxidation was lower in MDA-2J2 cells than in control cells, and the paclitaxel-mediated increase in peroxidation was attenuated. The mitochondrial complex III inhibitor antimycin A modulated basal and paclitaxel-activated reactive oxygen species (ROS) formation in control cells; paclitaxel-activated ROS production was also modulated by the NADPH oxidase inhibitor diphenyleneiodonium. Paclitaxel increased the formation of protein adducts by the reactive aldehyde 4-hydroxynonenal that is produced by lipid peroxidation; adduct formation was attenuated in MDA-2J2 cells. ALDH1A1 expression and activity was strongly upregulated in MDA-2J2 cells that was attributed to CYP2J2-derived 14,15-epoxyeicosatrienoic acid (14,15-EET); the 8,9- and 11,12-EET regioisomers did not activate ALDH1A1 expression. Silencing of ALDH1A1 restored the sensitivity of MDA-2J2 cells to paclitaxel, as indicated by a more pronounced decrease in proliferation, and greater increases in caspase activity and formation of ROS to levels comparable with control cells. Similar findings were observed with doxorubicin, sorafenib and staurosporine, that also promoted ROS-mediated cell death that was attenuated in MDA-2J2 cells and reversed by ALDH1A1 gene silencing. These findings implicate ALDH1A1 as an important gene that is activated in MDA-MB-468-derived cells that contain high levels of CYP2J2. ALDH1A1 modulates the production of ROS by anti-cancer agents such as paclitaxel and diminishes their efficacy. Future approaches could adapt this information to facilitate the targeting of ALDH1A1 to promote the efficacy of ROS-generating cytotoxic agents and enhance the treatment of breast cancer.

Quantitative Analysis of Uveitis Macular Edema in Multiple Sclerosis Patients Receiving Deep Posterior Sub-Tenon Triamcinolone Acetonide Injection.

AIM: We aimed to analyze the effects of adjunctive posterior sub-Tenon capsule triamcinolone acetonide injection in the treatment of intermediate uveitis macular edema in multiple sclerosis patients that could not be controlled by systemic corticosteroid medications and immunomodulators. METHODS: The study included 30 eyes of 25 patients with multiple sclerosis who received a posterior sub-Tenon injection of 40 mg/mL triamcinolone acetonide. Parameters monitored for therapy efficiency were best-corrected visual acuity, intraocular pressure, central foveal thickness (CFT), and fluorescein angiography (FA) scores. RESULTS: Mean best-corrected visual acuity was significantly improved at the control visit 0.15 ± 0.10 versus baseline 0.40 ± 0.20 logMAR (p < 0.05). Six eyes showed intraocular pressure spikes requiring topical antiglaucomatous treatment. Mean CFT and FA scores were significantly decreased versus baseline (CFT: 345 ± 50 µm; FA score: 3.4 ± 1.0) compared with the 12-week control visit (CFT: 219 ± 35 µm; FA score: 1.6 ± 1.1; p < 0.001). CONCLUSION: Posterior sub-Tenon injection of triamcinolone acetonide significantly improved visual acuity and decrease macular edema in patients with intermediate uveitis associated with multiple sclerosis.

The distribution of epidermolysis bullosa in Australia with a focus on rural and remote areas.

BACKGROUND/OBJECTIVES: Patients with epidermolysis bullosa (EB) require specialised medical care. In Australia this expertise is located in the major cities, with patients living in rural and remote areas having reduced access to these services. We aim to analyse the geographical distribution of patients with EB in Australia to determine the relevance of this potential geographical disadvantage for this population. METHODS: Using postal codes obtained from the Australian National Diagnostic Laboratory Database for EB and the Australasian EB Registry, living patients with EB in Australia were categorised using the Australian standard geographical classification, remoteness areas. An analysis of EB subtype, including severity was also performed. RESULTS: A total of 318 patients were categorised, of whom 221 lived in major cities, 65 in inner regional areas, 26 in outer regional areas, four in remote and two in very remote areas. Half the patients living in remote and very remote areas had severe forms of EB. CONCLUSIONS: A significant proportion of patients with EB live outside the major cities in Australia. Half of the patients living in remote and very remote areas had severe forms of EB. Targeted strategies to improve access to EB-specific medical care may be needed for patients living in rural and remote areas.

Activation of the pro-migratory bone morphogenetic protein receptor 1B gene in human MDA-MB-468 triple-negative breast cancer cells that over-express CYP2J2.

Secondary metastases are the leading cause of mortality in patients with breast cancer. Cytochrome P450 (CYP) 2J2 (CYP2J2) is upregulated in many human tumors and generates epoxyeicosanoids from arachidonic acid that promote tumorigenesis and metastasis, but at present there is little information on the genes that mediate these actions. In this study MDA-MB-468 breast cancer cells were stably transfected with CYP2J2 (MDA-2J2 cells) and Affymetrix microarray profiling was undertaken. We identified 182 genes that were differentially expressed in MDA-2J2 cells relative to control (MDA-CTL) cells (log[fold of control] ≥2). From gene ontology pathway analysis bone morphogenetic protein (BMP) receptor 1B (BMPR1B) emerged as an important upregulated gene in MDA-2J2 cells. Addition of the BMPR1B ligand BMP2 stimulated the migration of MDA-2J2 cells, but not MDA-CTL cells, from 3D-matrigel droplets. Migration of MDA-2J2 cells was prevented by the BMPR antagonist dorsomorphin. These findings indicate that over-expression of CYP2J2 in MDA-MB-468-derived breast cancer cells activates BMPR1B expression that may contribute to increased migration. Targeting BMPR1B may be a novel approach to inhibit the metastatic activity of breast cancers that contain high levels of CYP2J2.

Targeting Angiogenesis in Cancer Treatments: Where do we Stand?

Since early seventies of the twentieth century, through seminal work of Judah Folkman, angiogenesis, the process of new blood vessel sprouting from the existing vasculature, was recognized as a necessary part of wound healing, development of placenta, tissue growth and regeneration as well as cancer progression. This process is induced by low tissue oxygenation and it is a crucial prerequisite for rapid tissue growth, providing proper oxygen supply and removal of toxic metabolites. Suppression of angiogenesis as a way of slowing down tumor progression continues to be one of the most important areas of cancer research. The angiogenic process is relatively complex and it is regulated by numerous pro- and anti-angiogenic factors. Intensive research in the last twenty years resulted in identification of more than 300 angiogenesis inhibitors, a trend that is expected to continue. Unfortunately, most of these treatments have demonstrated unacceptable toxicities or failed to show activity in clinical studies. Although not yet completely understood, the complex process of tumor angiogenesis involves highly regulated orchestration of multiple activating and inhibiting factors. Vascular endothelial growth factor (VEGF) and its cognate receptors appear to play a central role in angiogenesis activation. Thus, initial efforts to develop anti-angiogenic treatments focused largely on inhibiting VEGF action. Such approaches, however, often lead to transient responses due to multiple pathways able to compensate for a single pathway inhibited. Accordingly, more recent treatments have focused on simultaneous inhibition of multiple signaling pathways. This review concentrates on identifying those anti-angiogenic treatments that made to the clinic by receiving approval by USA Food and Drug Administration (FDA) as treatments for cancer. Regardless of observed problems, it is an imperative that research in angiogenesis regulation continues. Consequently, pharmacological manipulation of angiogenesis may yet to introduce truly new pharmacological therapies into the field of cancer therapy, the field that was rather dormant in the last several decades. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

In Vitro Evaluation of Nanoscale Hydroxyapatite-Based Bone Reconstructive Materials with Antimicrobial Properties.

In the field of oral implantology the loss of bone tissue prevents adequate patient care, and calls for the use of synthetic biomaterials with properties that resemble natural bone. Special attention is paid to the risk of infection after the implantation of these materials. Studies have suggested that some nanocontructs containing metal ions have antimicrobial properties. The aim of this study was to examine the antimicrobial and hemolytic activity of cobalt-substituted hydroxyapatite nanoparticles, compared to hydroxyapatite and hydroxyapatite/poly-lactide-co-glycolide. The antibacterial effects of these powders were tested against two pathogenic bacterial strains: Escherichia coi (ATCC 25922) and Staphylococcus aureus (ATCC 25923), using the disc diffusion method and the quantitative antimicrobial test in a liquid medium. The quantitative antimicrobial test showed that all of the tested biomaterials have some antibacterial properties. The effects of both tests were more prominent in case of S. aureus than in E coli. A higher percentage of cobalt in the crystal structure of cobalt-substituted hydroxyapatite nanoparticles led to an increased antimicrobial activity. All of the presented biomaterial samples were found to be non-hemolytic. Having in mind that the tested of cobalt-substituted hydroxyapatite (Ca/Co-HAp) material in given concentrations shows good hemocompatibility and antimicrobial effects, along with its previously studied biological properties, the conclusion can be reached that it is a potential candidate that could substitute calcium hydroxyapatite as the material of choice for use in bone tissue engineering and clinical practices in orthopedic, oral and maxillofacial surgery.

Sexual Dimorphism in the Dimensions of Teeth in Serbian Population.

The study of teeth is of great interest to anthropologists, biologists, orthodontists and forensic scientists. The existence of sexual dimorphism in permanent teeth is a known phenomenon. Aim of this study was to analyze the presence of sexual dimorphism in the mesiodistal and vestibulolingual diameter of permanent teeth in the sample of Serbian population. Measurements were taken on plaster casts of 201 individuals of both sexes, ages between 18-25 years, using a digital caliper with 0.01 mm precision. The mesiodistal and vestibulolingual diameter of each permanent tooth was determined. A Student's t-test and a Mann-Whitney U test were used to statistically analyze the obtained results. There were no statistically significant differences in the teeth crown diameter between the right and left side of the same dental arch. Majority of the teeth examined were larger in male than in female patients. Statistically significant difference in the mesiodistal diameter of male and female maxillary and mandibular canines was found. The results of this study indicate that there are significant differences in teeth size between sexes in Serbian population. Males have larger diameters in teeth crowns than females. Canines show the greatest dimorphism.

Relentless placoid chorioretinitis ­ A case report.

Introduction: Relentless placoid chorioretinitis is an entity which belongs to the group of an atypical intermediate form of primary inflammatory choriocapillaropathies, resembling both acute posterior multifocal placoid pigment epitheliopathy and serpiginous choroiditis, but the retinal distribution and clinical course are not the same. Because of this similarity this entity was termed "AMPPiginous". This entity was first described by Jones et al. in 2000. The aim of our case report is to present a very specific case where the clinical course was progressive, with loss of vision in the affected eye. Case Outline: A 31-year-old man, with no previous ophthalmic diseases, was hospitalized at the Clinic of Ophthalmology, Clinical Center Kragujevac, because of a reduction of vision in the right eye, and scotoma and metamorphopsia in the left eye. The clinical course of retinal lesions in the left eye resembled the changes observed in acute posterior multifocal placoid pigment epitheliopathy, and the right eye changes were between acute posterior multifocal placoid pigment epitheliopathy and serpiginous choroiditis. The diagnosis of relentless placoid chorioretinitis was confirmed after clinical, laboratory, immunological, virological, and angiography examinations. Conclusion: The progressive clinical course of the disease, complemented by multimodal imaging and extensive laboratory diagnostics, has led us to the diagnosis of relentless placoid chorioretinitis. The combined anti-inflammatory and immunomodulatory therapy led to the stabilization of visual acuity of the left eye as opposed to the right, where there has been no recovery.

Prostanoids regulate angiogenesis acting primarily on IP and EP4 receptors.

Angiogenesis is regulated by numerous activators and inhibitors, including prostanoids. Although many studies have identified their roles in inflammation, regulatory functions of prostanoids in angiogenesis are poorly understood. Here, we compared the activation of angiogenesis in vitro by two prostanoids with important vascular roles: prostaglandin E2 (PGE2) - thought to be the most important prostanoid activator of angiogenesis - and prostaglandin I2 (prostacyclin or PGI2), whose receptors are predominantly expressed in endothelial cells. Both of these prostanoids activate G-protein coupled receptors: EP1, EP2, EP3 and EP4 by PGE2 and IP by prostacyclin. Human umbilical vein endothelial cells (HUVECs) were used to characterize two pivotal pro-angiogenic processes in vitro: cell migration (using the matrigel droplet assay developed in our laboratory) and "tube formation" (a widely accepted method of assessing formation of blood vessel precursors). The suppression of cell migration and tube formation by the IP-specific antagonist CAY10441 was more extensive (~80%) than by the EP4-specific antagonist L-161,982 (~20%). AH6809, an antagonist of EP1, EP2 and EP3 receptors did not significantly suppress angiogenesis. Expression of the pro-angiogenic receptors KDR and Tie-2 in HUVECs was preferentially suppressed by antagonism of IP and EP4 receptors, respectively. EP4 and IP receptor agonists elicited biphasic actions on angiogenic processes in which there was activation at low concentration, and rapid desensitization at high concentrations - a characteristic common to many G-protein coupled receptors. Together these findings suggest that the prostacyclin-IP pathway plays a major role in the regulation of pro-angiogenic processes in HUVECs.

Pro-migratory actions of the prostacyclin receptor in human breast cancer cells that over-express cyclooxygenase-2.

Metastasis is the major cause of death in cancer patients. Elevated expression of cyclooxygenase-2 (COX-2) is observed in many human cancers and over-production of downstream prostaglandins (PGs) has been shown to stimulate metastasis. A role for increased PGE2 production has been proposed, but whether other PGs contribute is currently unclear. In this study the pro-migratory actions of individual PGs were evaluated in MDA-MB-468 breast cancer cells that stably over-expressed COX-2 (MDA-COX-2 cells); cell migration was quantified using 3D-matrigel droplet assays. Inhibition of the prostacyclin and PGE synthases, but not alternate prostanoid synthases, prevented the increase in MDA-COX-2 cell migration produced by arachidonic acid (AA); direct treatment of cells with the stable prostacyclin analogue cicaprost also promoted migration. Pharmacological antagonism and knockdown of the IP receptor decreased cell migration, while antagonists of the alternate DP, EP2, FP, and TP prostanoid receptors were inactive. In support of these findings, activation of the IP receptor also enhanced migration in the MDA-MB-468, MDA-MB-231 and A549 cell lines, and IP receptor knock-down in MDA-COX-2 cells decreased the expression of a number of pro-migratory genes. In further studies, the prostacyclin/IP receptor and PGE2/EP4 receptor pathways were found to be functionally independent and the inhibition of phosphatidylinositol 3-kinase (PI3K) and p38 mitogen-activated protein kinase (MAPK) selectively impaired the IP-receptor-dependent migration in MDA-COX-2 cells. Taken together, the prostacyclin/IP/PI3K-p38 MAPK axis has emerged as a novel pro-migratory pathway in breast cancer cells that over-express COX-2. This information could be utilized in novel treatment strategies to minimize tumor metastasis.