Proliferation Factor Research Articles

Anti-Inflammatory Drugs

Inflammation is the result of concerted participation of a large number of vasoactive, chemotactic and proliferative factors at different stages and is a protective phenomenon of the body to external or internal trauma. The treatment of patients with inflammation involves two primary goals. First, the relief of pain, which is often the presenting symptom, and secondly slowing or arrest of the tissue damaging process. The anti inflammatory drugs belong to either steroidal group or non steroidal group. The glucocorticosteroid agents (steroids) are very effective anti-inflammatory agents clinically used. Unfortunately the toxicity associated with chronic corticosteroid therapy limits their use as anti- inflammatory agents except in the control of acute flare- ups of joint diseases. They act by inhibition of the release of prostaglandins by preventing the activation of Phospholipase A2. But t steroidsdo not come in the purview of this article.The other group of anti-inflammatory drugs is the non steroidal anti inflammatory drugs (NSAIDs) which play a significant role in treatment of inflammatory conditions.

Proliferation Activity Is Significantly Elevated in Partially Embolized Cerebral Arteriovenous Malformations

Background: The natural history of cerebral arteriovenous malformations (AVMs) is yet to be determined. It has been shown that angiogenic factors are involved in the pathogenesis of AVMs, in particular in partially embolized lesions. This study was conducted to investigate the expression of angiogenic and proliferative factors in relation to different clinical conditions and treatment modalities. Methods: Immunohistochemistry was performed for 145 consecutive cases of cerebral AVMs. The specimens were stained with antibodies against VEGF, bFGF, Ki 67, CD 34 and CD 31. Expression was correlated with clinical presentation (haemorrhage, seizures or other symptoms), AVM localization, size, eloquence and venous drainage, as well as with preoperative AVM embolization. Results: Whereas no correlation was found between the expression of angiogenic factors and different clinical conditions, we observed a significantly increased proliferation activity as shown by Ki 67 expression in patients with intracerebral haemorrhage (p = 0.02) and in patients with preoperative embolization (p = 0.02). Conclusions: Increased proliferation activity in partially embolized AVMs supports a ‘no-touch’ strategy and clinical observation in high-risk AVMs and demands complete AVM elimination in treatable lesions.

Effect of different concentrations of neogenin on proliferation, apoptosis and related proliferative factors in human trophoblasts

The underlying effect of different concentrations of neogenin on proliferation, apoptosis and the related proliferative factors in human trophoblasts was explored in order to understand the function of neogenin during placentation. TEV-1 cell line was cultured and the expression of netrin-1 was detected by using indirect cellular immunofluorescence. Exponentially growing TEV-1 cells were treated by different concentrations of neogenin (0, 1, 5, 10, 50 ng/mL) for 24 h. Cell viability was measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. TEV-1 cell apoptosis was assessed by flow cytometry (FCM). The expression of netrin-1 mRNA and protein in TEV-1 cells was examined by using real-time PCR and Western blot, respectively. It was found that immunoreactivity for netrin-1 was observed in cytoplasm of the trophoblasts. Immediately after treatment with different concentrations of neogenin for 24 h, the netrin-1 expression began to increase. Real-time PCR revealed that the expression level of netrin-1 mRNA was 37.59+/-10.25 times higher than control group when TEV-1 cells were exposed to 50 ng/mL neogenin (P<0.01), and the same tendency was seen by using Western blot. MTT results showed that proliferation of TEV-1 cells was independent of neogenin. Meanwhile, apoptosis was significantly increased to (22.15+/-6.15)% at 50 ng/mL neogenin and (6.55+/-0.25)% without neogenin (P<0.01). It is suggested that neogenin regulates proliferation and apoptosis of TEV-1 cells. And it can enhance the ability of TEV-1 cells to express netrin-1 in a dose-dependent manner. Neogenin may play an important biological role in the normal human pregnancy and contribute to the physiological pregnancy process.

Hyperglycaemia protects the heart after myocardial infarction: aspects of programmed cell survival and cell death

Exposure to a high glucose medium or diabetes has been found to protect the heart against ischaemia. The activation of antiapoptotic and proliferative factors seems to be involved in this cardioprotection. This study was designed to evaluate the role of hyperglycaemia in cardiac function, programmed cell survival, and cell death in diabetic rats after myocardial infarction (MI). Male Wistar rats were divided into four groups (n = 8): control (C), diabetic (D), myocardial infarcted (MI), and diabetic myocardial infarcted (DI). The following measures were assessed in the left ventricle: size of MI, systolic and diastolic function by echocardiography, cytokines by ELISA (TNF-alpha, IL-1beta, IL-6, and IL-10), gene expression by real-time PCR (Bax, Fas, p53, Bcl-2, HIF1-alpha, VEGF, and IL8r), caspase-3 activity by spectrofluorometric assay, glucose transporter type 1 and 4 (GLUT-1 and GLUT-4) protein expression by western blotting, and capillary density and fibrosis by histological analysis. Systolic function was improved by hyperglycaemia in the DI group, and this was accompanied by no improvement in diastolic dysfunction, a reduction of 36% in MI size, reduced proinflammatory cytokines, apoptosis activation, and an increase in cell survival factors (HIF1-alpha, VEGFa and IL8r) assessed 15 days post-MI. Moreover, hyperglycaemia resulted in angiogenesis (increased capillary density) before and after MI, accompanied by a reduction in fibrosis. Together, these results suggest that greater plasticity and cellular resistance to ischaemic injury result from chronic diabetic hyperglycaemia in rat hearts.

Effects of 17β-Estradiol on Preadipocyte Proliferation in Human Adipose Tissue: Involvement of IGF1-R Signaling

Estrogens are known to stimulate the proliferation of human preadipocytes. However, the molecular mechanisms underlying the increased cell growth by these steroids are poorly understood. In the present study, we have demonstrated that the proliferative effect of 17beta-estradiol involves the induction of both cell cycle gene expressions, c-myc and cyclin D1. Moreover, the mitogenic effects of 17beta-estradiol are suppressed by the pure antagonist ICI 182780 suggesting that estradiol action is mediated by estrogen receptor (ER). We have also shown that 17beta-estradiol is able to inhibit human preadipocyte apoptosis capacity as reflected by DNA fragmentation experiments and the mRNA expression of the pro- and antiapoptotic genes. Finally, 17beta-estradiol significantly induces both mRNA and protein expression of RIGF1 in human preadipose cells via ER and thus reinforces the signaling pathway of the proliferative factor, IGF1. Taken together, these data reinforce the concept of cross-talk between IGF1- and ER-signaling pathways in preadipocytes and indicate that IGFI may be a critical regulator of estrogen-mediated preadipose growth.

NPY augments the proliferative effect of FGF2 and increases the expression of FGFR1 on nestin positive postnatal hippocampal precursor cells, via the Y1 receptor

We have shown that neuropeptide Y (NPY), a peptide neurotransmitter released by hippocampal interneurons, is proliferative for hippocampal neural stem progenitor cells (NSPCs) via the Y1 receptor. Fibroblast growth factor (FGF) 2, released predominantly by astrocytes, is also a powerful mitogen for postnatal and adult NSPCs, via the FGFR1 receptor. Knockout studies show that NPY and FGF2 are individually necessary, but not sufficient, for seizure-induced neurogenesis, suggesting a possible interaction. Here, we examined for interactions between NPY and FGF2 on NSPCs from the postnatal hippocampus and report that the combination of NPY and FGF2 significantly shortens the cell cycle time of nestin positive NSPCs, more than either factor alone. This augmentation of proliferation rate is NPY Y1 receptor mediated, and Y1 receptor activation increases both FGFR1 mRNA and protein in NSPC cultures. NSPCs immunostain for both Y1 and FGFR1 receptors and the interaction is specific for dentate NSPCs. This is the first report of a proliferative factor that augments the proliferative effect of FGF2 and is the first evidence of a positive proliferative interaction between a glial growth factor and a neuronal transmitter, identifying a novel neural activity driven mechanism for modulating the proliferation of hippocampal NSPCs.

Inflammation and Pulmonary Hypertension

Pulmonary hypertension (PH) is a serious disorder with high morbidity and mortality rate. Evidence is accumulating to suggest that inflammation plays a significant role in the pathogenesis of PH. Endothelial cells play an important role in inflammation and immune reactions, and inflammatory cytokines cause endothelial dysfunction. Endothelial dysfunction is a hallmark of PH, consisting of reduced availability of vasodilators and antiproliferative factors and increased production of vasoconstrictors and vascular proliferative factors. Up-regulation of inflammatory cytokines and perivascular inflammatory cell infiltration have been detected in the lungs of patients with idiopathic PH. Prevalence of PH in patients with systemic inflammatory diseases is well documented. Interestingly, a significant loss of endothelial caveolin-1, a potent immunomodulator and an inhibitor of cell proliferation, has been reported in human and experimental forms of PH. Reduction in the expression of caveolin-1 is known to result in the removal of antiproliferative activities, thus, leading to deregulated vascular cell proliferation. This article summarizes the roles of inflammation and endothelial caveolin-1 and their possible interrelationship in PH.

128 Locoregional recurrences in triple-negative, node-negative early stage breast cancer treated with breast-conserving treatment

prognosis (similar to grade 1) and one with a bad prognosis (similar to grade 3). We therefore also raised the question if a single proliferative factor, i.e. cyclin A, can be used for this purpose. Material and Methods: In 219 consecutive premenopausal node negative patients, cyclin A was determined with immunohistochemistry on tissue microarray. High cyclin A was defined as the 7 decile of positive cells. Only 13% of the patients received adjuvant systemic therapy. Cox proportional hazards regression was used to model the impact of the prognostic factors on distant disease-free survival (DDFS). Due to nonproportional hazards, the analysis was restricted to the first five years after diagnosis, a time period during which 34 patients developed distant recurrences. Results: Cyclin A was associated to DDFS in univariate analysis (hazard ratio (HR) 3.6, 95% confidence interval (CI): 1.8−7.1, p < 0.001). Corresponding HR:s were 2.7 for Ki67 (95%CI: 1.3−5.5, p = 0.005) and 2.7 for grade 3 vs 1+2 (95%CI: 1.3−5.2, p = 0.004). HER2, age, ER and progesterone receptor were also significant factors, whereas tumor size was not. Cyclin A could divide histological grade 2 into two groups with significantly different DDFS (HR: 15, 95%CI: 4.3−52, p < 0.001). In the grade 1 and 3 subgroups, cyclin A was not a prognostic factor. When subdividing according to ER status, cyclin A was a prognostic factor in the ER positive subgroup, but not in the ER negative (HR: 5.8, 95%CI: 2.2−16, p < 0.001) vs. 1.5 (95%CI: 0.6−3.9, p = 0.44). In multivariate analysis, cyclin A was an independent prognostic factor for DDFS (HR: 2.9, 95%CI: 1.2−7.0, p = 0.018), together with HER2 and age. Due to colinearity, histological grade and Ki67 were not included in the same model. Conclusion: In this study cyclin A was an independent prognostic factor for premenopausal patients with node-negative breast cancer, but only in the ER positive subgroup. Similar to gene expression analyses, cyclin A can subdivide histological grade 2 breast cancer into two groups with different prognosis. Taken together, cyclin A may be an alternative or a complement to histological grade and Ki67 for prognostic considerations.

Reactive oxygen species differently regulate renal tubular epithelial and interstitial cell proliferation after ischemia and reperfusion injury

Reactive oxygen species (ROS) function as an inducer of cell death and survival or proliferative factor, in a cell-type-specific and concentration-dependent manner. All of these roles are critical to ischemia-induced renal functional impairment and progressive fibrotic changes in the kidney. In an effort to define the role of ROS in the proliferation of tubular epithelial cells and of interstitial cells in kidneys recovering after ischemia and reperfusion (I/R) injury, experimental mice were subjected to 30 min of bilateral kidney ischemia and administered with manganese(III) tetrakis(1-methyl-4-pyridyl) porphyrin (MnTMPyP), a superoxide dismutase mimetic, from 2 to 15 days after I/R for 14 days daily (earlier and longer) and from 8 to 15 days after I/R for 8 days daily (later and shorter). Cell proliferation was assessed via 5'-bromo-2'-deoxyuridine (BrdU) incorporation assays for 20 h before the harvest of kidneys. After I/R, the numbers of BrdU-incorporating cells increased both in the tubules and interstitium. MnTMPyP administration was shown to accelerate the proliferation of tubular epithelial cells, presenting tubule-specific marker proteins along tubular segments, whereas it attenuated the proliferation of interstitial cells, evidencing α-smooth muscle actin, fibroblast-specific protein-1, F4/80, and NADPH oxidase-2 proteins; these results indicated that ROS attenuates tubular cell regeneration, but accelerates interstitial cell proliferation. Earlier and longer MnTMPyP treatment more effectively inhibited tissue superoxide formation, the increment of interstitial cells, and the decrement of epithelial cells compared with later and shorter treatment. After I/R, apoptotic cells appeared principally in the tubular epithelial cells, but not in the interstitial cells, thereby indicating that ROS is harmful in tubule cells, but is not in interstitial cells. In conclusion, ROS generated after I/R injury in cell proliferation and death performs a cell-type-specific and concentration-dependent role, even within the same tissues, and timely intervention of ROS is crucial for effective therapies.

Immunoexpression of Ki67, proliferative cell nuclear antigen, and Bcl-2 proteins in a case of ameloblastic fibrosarcoma

Ameloblastic fibrosarcoma (AFS), regarded as the malignant counterpart of the benign ameloblastic fibroma, is an extremely rare odontogenic neoplasm with only 68 cases reported in the English literature up to 2009. It is composed of a benign odontogenic epithelium, resembling that of ameloblastoma, and a malignant mesenchymal part exhibiting features of fibrosarcoma. Due to the rarity of the lesion, little is known about its molecular pathogenesis; therefore, in the current study, we sought to evaluate the immunoexpression of Ki67, proliferative cell nuclear antigen, and Bcl-2 proteins in AFS, comparing the results obtained with its benign counterpart, as well as to report a new case of this rare entity affecting a 19-year-old female patient. The results obtained revealed that all the proteins evaluated were overexpressed in the malignant mesenchymal portion of AFS if compared with ameloblastic fibroma, suggesting that nuclear proliferative factors such as Ki67 and proliferative cell nuclear antigen, in association to histopathologic features, may be useful markers for identifying the malignancy and that, despite the lack of molecular analysis in the case reported, Bcl-2 alteration may play a role in AFS pathogenesis.

Progressive endothelial cell damage in an inflammatory model of pulmonary hypertension

ABSTRACTMonocrotaline (MCT)-induces progressive disruption of endothelial cell membrane and caveolin-1 leading to pulmonary arterial hypertension (PAH). Treatment instituted early rescues caveolin-1 and attenuates PAH. To test the hypothesis that the poor response to therapy in established PAH is due to progressive deregulation of multiple signaling pathways, the authors investigated time-dependent changes in the expression of caveolin-1, gp130, PY-STAT3, Bcl-xL, and the molecules involved in NO signaling pathway (endothelial nitric oxide synthase [[eNOS]], heat sock protein 90 [[HSP90]], Akt, soluble guanylate cyclase [[sGC]] α1 and β1 subunits). PAH and right ventricular hypertrophy (RVH) were observed at 2 and 3 weeks. Progressive loss of endothelial caveolin-1 and sGC (α1, β1), PY-STAT3 activation, and Bcl-xL expression were observed at 1 to 3 weeks post-MCT. The expression of gp130 increased at 48 hours and 1 week, with a subsequent loss at 2 and 3 weeks. The expression of eNOS increased at 48 hours and 1 week post-MCT, with a significant loss at 3 weeks. The expression of HSP90 and Akt decreased at 2 and 3 weeks post-MCT concomitant with PAH. Thus, MCT induces progressive loss of membrane and cytosolic proteins, resulting in the activation of proliferative and antiapoptotic factors, and deregulation of NO signaling leading to PAH. An attractive therapeutic approach to treat PAH may be an attempt to rescue endothelial cell membrane integrity.

Pkc alpha phosphorylates cytosolic nf-kappab/p65 and pkc delta delays nuclear translocation of nf-kappab/p65 in u1242 glioblastoma cells

Protein kinase-C (PKC) and NF-kappaB are involved in cell survival, proliferation, migration and radioresistance in glioblastoma multiforme (GBM). We sought to determine the interaction between PKC and NF-kappaB pathways. The activation of NF-kappaB by PKC alpha and PKC delta was assessed by Western blotting after the stimulation with Phorbol 12- Myristate 13-Acetate (PMA). Gene silencing of PKC alpha , PKC delta and NFkappaB/ p65 with siRNA interference was utilized to evaluate their roles in NFkB activation and cell proliferation. PMA induced the phosphorylation of NF-kappaB/p65 by PKC alpha. Gene silencing with siRNA against NF-kappaB/p65 inhibited [3H]-thymidine incorporation in U1242 GBM cells. PKC delta decelerated the nuclear translocation of activated NF-kappaB/p65 up to 4 hours after the stimulation. PMA induced death was not observed in PKC delta silenced cells where activated NF-kappaB/p65 was located immediately in the nucleus. NF-kappaB/p65 is pro-survival and proliferative factor in U1242 GBM cells. PKC alpha is needed to phosphorylate NF-kappaB/p65. PKC delta delays the translocation of active NF-kappaB/p65 into the nucleus. PMA-induced cell death occurred if the phospho-NF-kappaB/p65 was prohibited from entering the nucleus in PKC delta positive cells. Translocation of phosphorylated form of NF-kappaB into the nucleus is critical in GBM cell proliferation.

Autocrine Bone Morphogenetic Protein-9 Signals through Activin Receptor-like Kinase-2/Smad1/Smad4 to Promote Ovarian Cancer Cell Proliferation

Bone morphogenetic proteins (BMPs) act as central regulators of ovarian physiology and may be involved in ovarian cancer development. In an effort to understand these processes, we characterized transforming growth factor beta/BMP receptor and Smad expression in immortalized ovarian surface epithelial cells and a panel of ovarian cancer cell lines. These studies prompted us to evaluate the potential role of BMP9 signaling in ovarian cancer. Using small interfering RNA, ligand trap, inhibitor, and ligand stimulation approaches, we show that BMP9 acts as a proliferative factor for immortalized ovarian surface epithelial cells and ovarian cancer cell lines, signaling predominantly through an ALK2/Smad1/Smad4 pathway rather than through ALK1, the major BMP9 receptor in endothelial cells. Importantly, we find that some ovarian cancer cell lines have gained autocrine BMP9 signaling that is required for proliferation. Furthermore, immunohistochemistry analysis of an ovarian cancer tissue microarray reveals that approximately 25% of epithelial ovarian cancers express BMP9, whereas normal human ovarian surface epithelial specimens do not. Our data indicate that BMP9 signaling through ALK2 may be a novel therapeutic target in ovarian cancer.

Anti-tumor effect of apicidin on Ishikawa human endometrial cancer cells both in vitro and in vivo by blocking histone deacetylase 3 and 4

Histone deacetylase (HDAC) inhibitors are a new class of anticancer agents that act by inhibiting cancer cell proliferation and inducing apoptosis both in vitro and in vivo. This study examined the anti-tumor effect of apicidin on human endometrial cancer Ishikawa cells in an animal model by inhibiting specific HDAC expression. Nude mice were injected subcutaneously (s.c.) with Ishikawa cells, and the levels of cell proliferation and apoptosis were measured in the tumor tissues after an apicidin treatment. The expression patterns of a specific HDAC class by apicidin were measured in Ishikawa endometrial cancer both in vitro and in vivo. The tumor volume and weight were measured after the apicidin treatment. Apicidin significantly increased the acetylated histone H3 levels in an Ishikawa cells in vitro culture but the levels of HDAC3 and HDAC4 expression were significantly decreased. Apicidin suppressed the tumor growth of transplanted Ishikawa cells, the expression of proliferative cell nuclear antigen (PCNA) and vascular endothelial growth factor (VEGF) in tumor xenograft model, respectively. The inhibitory effect of apicidin on tumor growth was mediated in part through the down-regulation of HDAC3 and HDAC4. We suggest that apicidin is an effective anti-tumor agent on human endometrial cancer cells, and acts by regulating cell proliferation and apoptosis through the down-regulation of HDAC3 and HDAC4.

IMATINIB MESYLATE TREATMENT FOR SEVERE PULMONARY ARTERIAL HYPERTENSION: A PROPOSED PHASE III 24-WEEK DOUBLE-BLIND PLACEBO-CONTROLLED RANDOMIZED CLINICAL TRIAL

PURPOSE: Pulmonary arterial hypertension (PAH) is a progressive condition with a poor prognosis. Platelet-derived growth factor receptor (PDGFR) signalling plays an important role in the pathobiology of this disease. We previously evaluated the use of imatinib, which inhibits PDGFR activity, in a phase II randomized clinical trial in PAH to evaluate safety, tolerability, and dosing. That phase II 24-week study suggested that imatinib is safe and well tolerated, and provided proof of concept for further studies evaluating its efficacy in PAH and suggested that patients on combination therapy with worse hemodynamics appeared to respond better than less impaired patients. This supports the use of agents targeting proliferative growth factor pathways in PAH. Particularly in the most severely affected but an additional study is needed to confirm these findings.

Evidence for a role of sphingosine-1 phosphate in cardiovascular remodelling in Fabry disease

A hallmark of Fabry disease is the concomitant development of left-ventricular hypertrophy and arterial intima-media thickening, the pathogenesis of which is thought to be related to the presence of a plasmatic circulating growth-promoting factor. We therefore characterized the plasma of patients with Fabry disease in order to identify this factor. Using a classical biochemical strategy, we isolated and identified sphingosine-1 phosphate (S1P) as a proliferative factor present in the plasma of patients with Fabry disease. Plasma S1P levels were significantly higher in 17 patients with Fabry disease compared with 17 healthy controls (225 +/- 40 vs. 164 +/- 17 ng/mL; P = 0.005). There was a positive correlation between plasma S1P levels and both common carotid artery intima-media thickness and left-ventricular mass index (r(2) = 0.47; P = 0.006 and r(2) = 0.53; P = 0.0007, respectively). In an experimental model, mice treated with S1P developed cardiovascular remodelling similar to that observed in patients with Fabry disease. Sphingosine-1 phosphate participates in cardiovascular remodelling in Fabry disease. Our findings have implications for the treatment of cardiovascular involvement in Fabry disease.

Phosphodiesterase type 5 inhibitors in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare disease characterized by vascular proliferation and remodeling, resulting in a progressive increase in pulmonary arterial resistance, right heart failure, and death. The pathogenesis of PAH is multifactorial, with endothelial cell dysfunction playing an integral role. This endothelial dysfunction is characterized by an overproduction of vasoconstrictors and proliferative factors, such as endothelin-1, and a reduction of vasodilators and antiproliferative factors, such prostacyclin and nitric oxide. Phosphodiesterase type 5 (PDE-5) is implicated in this process by inactivating cyclic guanosine monophosphate, the nitric oxide pathway second messenger. PDE-5 is abundantly expressed in lung tissue, and appears to be upregulated in PAH. Three oral PDE-5 inhibitors are available (sildenafil, tadalafil, and vardenafil) and are the recommended first-line treatment for erectile dysfunction. Experimental studies have shown the beneficial effects of PDE-5 inhibitors on pulmonary vascular remodeling and vasodilatation, justifying their investigation in PAH. Randomized clinical trials in monotherapy or combination therapy have been conducted in PAH with sildenafil and tadalafil, which are therefore currently the approved PDE-5 inhibitors in PAH treatment. Sildenafil and tadalafil significantly improve clinical status, exercise capacity, and hemodynamics of PAH patients. Combination therapy of PDE-5 inhibitors with prostacyclin analogs and endothelin receptor antagonists may be helpful in the management of PAH although further studies are needed in this area. The third PDE-5 inhibitor, vardenafil, is currently being investigated in PAH. Side effects are usually mild and transient and include headache, flushing, nasal congestion, digestive disorders, and myalgia. Mild and moderate renal or hepatic failure does not significantly affect the metabolism of PDE-5 inhibitors, whereas coadministration of bosentan decreases sildenafil and tadalafil plasma levels. Due to their clinical effectiveness, tolerance profile, and their oral administration, sildenafil and tadalafil are two of the recommended first-line therapies for PAH patients in World Health Organization functional classes II or III.

Differential Endothelin Receptor Expression and Function in Rat Myometrial Cells and Leiomyoma ELT3 Cells

Uterine leiomyoma are the most common benign tumors of the myometrium. We previously identified endothelin (ET)-1 as a proliferative and antiapoptotic factor in Eker rat-derived leiomyoma (ELT3) cells. A major role of ETB receptor in the prosurvival effect was revealed. Here we investigated, in ELT3 and myometrial cells, the respective contribution of ETA and ETB in the proliferative effect of ET-1. In myometrial cells, binding experiments show that ETA is almost exclusively expressed and stimulates phospholipase C (PLC) activity and ERK1/2 phosphorylation and proliferation. In ELT3 cells, ETB is expressed at about the same level as ETA, and the two receptors are differently coupled to Gi protein. The ETB agonist, sarafotoxin S6c, stimulates PLC activity 60% less than ET-1 but is as potent as ET-1 to increase ERK1/2 phosphorylation and induce proliferation. However, the ability of ETA to activate ERK1/2 is observed after ETB desensitization. Although ETA and ETB antagonists partially reduce ET-1 stimulated PLC activity, they are without effect on ET-1-induced ERK1/2 phosphorylation and proliferation. Only the simultaneous use of ETA and ETB antagonists reduces ET-1-triggered ERK1/2 activation. These unconventional properties of ETRs may reveal the existence of functional ETA-ETB heterodimers. Finally, treatment of ELT3 cells with ETB but not ETA-directed small interfering RNA reduces the proliferative effect of ET-1. All the data obtained in ELT3 cells strengthen the relation between ETB overexpression, which decreases the ETA to ETB ratio, and the ability of leiomyoma cells to highly proliferate and resist apoptosis.

The Effect of Thrombin Activation of Platelet-Rich Plasma on Demineralized Bone Matrix Osteoinductivity

Demineralized bone matrix is an osteoinductive and osteoconductive material that is often used in orthopaedic surgery to induce bone formation. Autologous platelet-rich plasma, which contains proliferative and chemoattractant growth factors, has been used as a demineralized bone matrix adjuvant with mixed results. One variable during clinical use appears to be whether the platelet-rich plasma is activated with thrombin or is implanted in a liquid form with intact platelets. The objective of the present study was to determine if platelet-rich plasma can increase the osteoinductivity of demineralized bone matrix when used without thrombin activation. The bioactivity of the demineralized bone matrix was evaluated in vitro by determining alkaline phosphatase production by C2C12 myoblast cells. The effect of thrombin activation on platelet-rich plasma was studied in vitro by evaluating osteosarcoma and bone marrow stromal cells for cell number and transforming growth factor-beta1 activation. Demineralized bone matrices supplemented with platelet-rich plasma, with or without thrombin activation, were implanted intramuscularly in athymic rats and were examined at fourteen, twenty-eight, and fifty-six days. Histological samples were analyzed for osteogenesis and chondrogenesis. Osteogenesis was further characterized on the basis of alkaline phosphatase activity. In vitro, thrombin triggered an immediate release of growth factors from the platelet-rich plasma, and the platelet-rich plasma increased the number of both osteosarcoma and stromal cells in a dose-dependent manner. Thrombin activation of the platelet-rich plasma eliminated such stimulatory effects. In vivo, the platelet-rich plasma stimulated chondrogenesis on Day 14 and osteogenesis on Days 28 and 56, whereas thrombin-activated platelet-rich plasma acted as an inhibitor of such events. In addition, inflammatory cells were detected in demineralized bone matrix samples that were mixed with thrombin-activated platelet-rich plasma. These cells were not present in matrix mixed with platelet-rich plasma alone. Platelet-rich plasma significantly increased in vivo demineralized bone matrix osteoinductivity only when used without thrombin activation.

TRIPLE THERAPY FOR AGE-RELATED MACULAR DEGENERATION

Choroidal neovascularization is a hallmark sign of wet age-related macular degeneration (AMD) but it is not an isolated feature. Several processes are likely to contribute to the fibrotic scarring and vision loss that accompanies progressive disease. In a case series, a triple therapy approach to wet AMD was based on the goals of halting choroidal neovascularization, controlling the inflammatory response, and modifying proliferative factors. To address each of these goals, respectively, patients received photodynamic therapy, bevacizumab, and the steroid dexamethasone. The encouraging rate of response, including significant improvements in visual acuity, is consistent with the combined activities of these agents and provides the basis for more definitive studies.