Adenosine A1 and A2a receptors modulate the nitrergic system in cell culture from dorsomedial medulla oblongata.

Adenosine and nitric oxide act on the fine-tuning regulation of neural cardiovascular control in the nucleus tractus solitarius (NTS). Although the interaction between adenosine and NO is well known in the periphery, the mechanisms by which adenosine interferes in the dynamics of nitrergic neurotransmission, related to neural control of circulation, are not completely understood and might be relevant for individuals predisposed to hypertension. In this study we evaluate the interaction between adenosinergic and nitrergic systems in cell culture from the dorsomedial medulla oblongata of Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR). Using quantification of nitrite levels, RT-PCR analysis and RNA interference we demonstrate that adenosine A1 (A1R) and A2a receptor (A2aR) agonists induce a concentration-dependent decrease and increase of nitrite and nNOS mRNA levels in cultured cells from WKY and SHR, respectively. These effects in nitrite levels are attenuated by the administration of A1R and A2aR selective antagonists, CPT and ZM 241385. Furthermore, knockdown of A1R and A2aR show an increase and decrease of nNOS mRNA levels, respectively. Pretreatment with the nonselective inhibitor of NOS, L-NAME, abolishes nitrite-increased levels triggered by CGS 21680 in WKY and SHR cells. Finally, it is shown that the cAMP-PKA pathway is involved in A1R and A2aR-mediated decrease and increase in nitrite levels in SHR and WKY cells. Our results highlight the influence of adenosine on nitric oxide levels in cultured cells from dorsal medulla oblongata of neonate WKY and SHR rats. In part, the modulatory profile is different in the SHR strain.

Effects of frutalin and doxorubicin on growth, ultrastructure and gene expression in goat secondary follicles cultured in vitro.

This study evaluated the effects of frutalin (0.6, 6.0 or 60.0 µg/mL) and doxorubicin (0.3 µg/mL) on survival, growth and ultrastructure of in-vitro cultured goat secondary follicles. The effects of these substances on the levels of mRNA for Casp3, Casp6, Bax, and Bcl2 were also investigated. Results showed that, after 6 days of culture, frutalin or doxorubicin reduced the percentage of normal follicles (P < 0.05), but doxorubicin had higher toxicity than frutalin. Except for follicles cultured with 0.6 µg/mL frutalin, follicular growth rate was reduced after culture with doxorubicin or frutalin (P < 0.05). The presence doxorubicin or 60.0 µg/mL frutalin increased the levels of mRNA for Casp3, Casp6, Bax, and Bcl2 (P < 0.05). Higher mRNA levels for Casp3, Casp6 and Bax were found in follicles cultured with doxorubicin, but higher levels of Bcl2 mRNA were found in follicles cultured with frutalin (P < 0.05). In conclusion, frutalin has lower toxic effects than doxorubicin on secondary follicles cultured in vitro.

Bioactive compounds from extra virgin olive oils: Correlation between phenolic content and oxidative stress cell protection.

When compared with other edible vegetable oils, the extra virgin olive oil (EVOO) exhibits excellent nutritional properties due to the presence of biophenolic compounds. Although they constitute only a very small amount of the unsaponifiable fraction of EVOO, biophenols strongly contribute to the sensorial properties of this precious food conferring it, for example, the bitter or pungent taste. Furthermore, it has been found that biophenols possess beneficial effects against many human pathologies such as oxidative stress, inflammation, cardiovascular diseases, cancer and aging-related illness. In the present work, the biophenolic content of 51 Italian and Spanish EVOOs was qualitatively and quantitatively identified and their antioxidant ability analyzed by oxygen radical absorbance capacity (ORAC) assay. Results indicated that the maximum relationship can be found if the ORAC value is correlated with the concentration of the large family composed by ligstroside and oleuropein derivatives together with their degradation products, hydroxytyrosol and tyrosol. Then, selected biophenolic extracts were tested in NIH-3T3 cell line to verify their ability in the recovery of the oxidative stress revealed by DCFH-DA assay. Results were linearly correlated with the concentration of ligstroside aglycone (aldehyde and hydroxyl form).

The endocannabinoid 2-arachidonoylglycerol dysregulates the synthesis of proteins by the human syncytiotrophoblast.

In recent years, endocannabinoids emerged as new players in various reproductive events. Recently, we demonstrated the involvement of 2-arachidonoylglycerol (2-AG) in human cytotrophoblast apoptosis and syncytialization. However, 2-AG impact in hormone production by the syncytiotrophoblast (hST) was never studied. In this work, we demonstrate that 2-AG activates cannabinoid (CB) receptors, exerting an inhibitory action on cyclic AMP/protein kinase A (cAMP/PKA) and mitogen-activated protein kinase (MAPK) p38 pathways, and enhancing ERK 1/2 phosphorylation. Furthermore, 2-AG affects the synthesis of human chorionic gonadotropin (hCG), leptin, aromatase, 3-ß-hydroxysteroid dehydrogenase (3-ß-HSD), and placental protein 13 (PP13). These 2-AG effects are mediated by the activation of CB receptors, in a mechanism that may involve p38, ERK 1/2 and cAMP/PKA pathways, which participate in the regulation of placental proteins expression. To our knowledge, this is the first study that associates the endocannabinoid signalling and endocrine placental function, shedding light on a role for 2-AG in the complex network of molecules that orchestrate the production of placental proteins essential for the gestational success.

The psychoactive compound of Cannabis sativa, Δ(9)-tetrahydrocannabinol (THC) inhibits the human trophoblast cell turnover.

The noxious effects of cannabis consumption for fertility and pregnancy outcome are recognized for years. Its consumption during gestation is associated with alterations in foetal growth, low birth weight and preterm labor. The main psychoactive molecule of cannabis, Δ(9)-tetrahydrocannabinol (THC) impairs the production of reproductive hormones and is also able to cross the placenta barrier. However, its effect on the main placental cells, the trophoblasts, are unknown. Actually, the role of THC in cell survival/death of primary human cytotrophoblasts (CTs) and syncytiotrophoblasts (STs) and in the syncytialization process remains to be explored. Here, we show that THC has a dual effect, enhancing MTT metabolism at low concentrations, whereas higher doses decreased cell viability, on both trophoblast phenotypes, though the effects on STs were more evident. THC also diminished the generation of oxidative and nitrative stress and the oxidized form of glutathione, whereas the reduced form of this tripeptide was increased, suggesting that THC prevents ST cell death due to an antioxidant effect. Moreover, this compound enhanced the mitochondrial function of STs, as observed by the increased MTT metabolism and intracellular ATP levels. These effects were independent of cannabinoid receptors activation. Besides, THC impaired CT differentiation into STs, since it decreased the expression of biochemical and morphological biomarkers of syncytialization, through a cannabinoid receptor-dependent mechanism. Together, these results suggest that THC interferes with trophoblast turnover, preventing trophoblast cell death and differentiation, and contribute to disclose the cellular mechanisms that lead to pregnancy complications in women that consume cannabis-derived drugs during gestation.

The endocannabinoid anandamide induces apoptosis in cytotrophoblast cells: involvement of both mitochondrial and death receptor pathways.

INTRODUCTION: A balanced proliferation, apoptosis and differentiation in trophoblast cells of the human placenta is crucial for a proper placental development. Alteration in trophoblast apoptosis and differentiation are associated with gestational-related complications, such as preeclampsia, intrauterine growth restriction or miscarriages. The endocannabinoids (eCBs) have been recognized as new interveners in pregnancy events such as implantation and decidualization. However, their importance in placentation is poorly understood. We hypothesise that these novel lipid mediators may intervene in cytotrophoblast apoptosis and, concomitantly, have a role during placental development. METHODS: primary human cytotrophoblasts (hCTs) and the human trophoblast-like choriocarcinoma cell line BeWo cells were exposed to Anandamide (AEA). It was investigated the cellular pathways involved in cell death, by the assessment of cell morphology, caspases activity, mitochondrial membrane potential (Δψm), reactive oxygen/nitrogen species (ROS/RNS) and western blot of cleaved Poly (ADP-ribose) polymerase 1 (PARP-1), truncated Bid (t-Bid) and IκB-α. RESULTS: AEA decreased hCTs viability and induced morphological features of apoptosis (chromatin condensation and fragmentation), caspase-3/7 activation and PARP-1 cleavage. In BeWo, AEA also increased the activities of caspase-3/7 and 9, induced loss in Δψm and production of ROS/RNS. These effects were reversed by either CB1 or CB2 antagonists, whereas the increase in caspase-3/7 activity was only reversed with CB2 blockage. AEA-treated cells showed increased caspase-8 activation and formation of t-Bid, suggesting the interplay between intrinsic and extrinsic apoptotic pathways. AEA also increased IκB-α expression, a NF-κB regulatory protein. CONCLUSION: Our results highlight the importance of eCBs in cytotrophoblast cell apoptosis and indicate that a crosstalk between intrinsic and extrinsic apoptotic pathways is involved in AEA-induced effects.

2-Arachidonoylglycerol impairs human cytotrophoblast cells syncytialization: influence of endocannabinoid signalling in placental development.

A balanced cytotrophoblast cell turnover is crucial for placental development and anomalies in this process associated with gestational diseases. The endocannabinoid system (ECS) has emerged as a new player in several biological processes. However, its influence during placental development is still unknown. We report here the expression of the endocannabinoid 2-arachidonoylglycerol (2-AG) main metabolic enzymes in human cytotrophoblasts and syncytiotrophoblast. We also showed that 2-AG induced a decrease in placental alkaline phosphatase activity, human chorionic gonadotropin secretion and Leptin mRNA levels. Moreover, 2-AG reduced glial cell missing 1 and syncytin-2 transcription and the number of nuclei in syncytium. These effects were mediated by cannabinoid receptors and may result from 2-AG inhibition of the cAMP/PKA signalling pathway. Our data suggest that 2-AG may interfere with the biochemical and morphological differentiation of human cytotrophoblasts, through a CB receptor-dependent mechanism, shedding light on a role for the ECS in placental development.

Caracterização do insumo ibuprofeno e a correlação com propriedades de dissolução e de fluxo / Characterization of ibuprofen raw material and correlation with dissolution and flow properties

Ibuprofen is a moderately active non-steroidal anti-inflammatorydrug, derived from β-phenylpropionic acid. Its analgesic action, which is related to its anti-inflammatoryproperties, is due to a decrease in the production of enzymes cyclo-oxygenase-1 (COX-1) and cyclo-oxygenase-2 (COX-2). Ibuprofen exhibits distinct morphologies when crystallized under different conditions. In this study, the characteristics of the ibuprofen raw material and their impact on drug dissolution and processing properties were analyzed. Samples of raw ibuprofen from 3 different manufacturers were characterized by a variety of techniques. The analysis confirmed that all 3 samples exhibited the same crystalline form; thus, polymorphism could be discarded as one of the causes of any variation in performance of the drug. The results showed that the physical characteristics of each sample influenced its flow and dissolution properties. In fact, there was a detectable variation in the physical characteristics of the drug among the 3 different manufacturers. This demonstrates the importance of testing the characteristics of the drug raw material in order to correlate them with its performance in processing and eventual use, enabling pharmacotechnical improvement and development...

O ibuprofeno é um agente anti-inflamatório não esteróide, derivado do ácido fenilpropiônico que possui atividade anti-inflamatória de ação moderada. Sua ação analgésica está relacionada às propriedades anti-inflamatórias devido à redução da produção da ciclooxigenase-1 (COX-1) e da ciclooxigenase-2 (COX-2). O ibuprofeno exibe diferentes morfologias quando cristalizado em diferentes solventes. Neste estudo, se avaliaram as características de matérias-primas do ibuprofeno e o impacto destas nas propriedades de dissolução e processamento. Foram avaliadas três matérias-primas do ibuprofeno de três diferentes fabricantes, utilizando variadas técnicas de caracterização. As análises confirmaram que todas apresentavam a mesma forma cristalina do ibuprofeno; assim, o polimorfismo foi descartado como uma das causas de influência na dissolução e no fluxo do fármaco. Os resultados mostraram que características físicas da matéria-prima ibuprofeno tiveram impacto nas propriedades de fluxo e dissolução e que existe uma variabilidade das características físicas do fármaco entre diferentes fabricantes. Isto mostra a importância da avaliação de características da matéria-prima para correlacioná-las com propriedades de desempenho, possibilitando o desenvolvimento e melhoramento farmacotécnico...

2-arachidonoylglycerol effects in cytotrophoblasts: metabolic enzymes expression and apoptosis in BeWo cells.

The major endocannabinoid (eCB) 2-arachidonoylglycerol (2-AG) is a member of the endocannabinoid system (ECS) that participates in cell proliferation and apoptosis, important events for the homoeostasis of biological systems. The formation of placenta is one of the most important stages of pregnancy and its development requires highly regulated proliferation, differentiation and apoptosis of trophoblasts. Anomalies in these processes are associated with gestational pathologies. In this work, we aimed to study the involvement of 2-AG in cytotrophoblast cell turnover. We found that 2-AG biosynthetic (diacylglycerol lipase A) and degradative (monoacylglycerol lipase) enzymes are expressed in human cytotrophoblasts and in BeWo cells. We also found that 2-AG induces a decrease in cell viability in a time- and concentration-dependent manner and exerts antiproliferative effects. The loss of cell viability induced by a 48-h treatment with 2-AG (10 µM) was accompanied by chromatin fragmentation and condensation, morphological features of apoptosis. Additionally, 2-AG induced an increase in caspase 3/7 and 9 activities, a loss of mitochondrial membrane potential (Δψm) and an increase in reactive oxygen species (ROS)/reactive nitrogen species (RNS) generation, suggesting the activation of the mitochondrial pathway. Moreover, whereas Δψm loss and ROS/RNS generation were significantly attenuated by the antagonists of both the cannabinoid receptors 1 and 2 (CB1 and CB2), the increase in caspase 3/7 and 9 activities and loss of cell viability were reversed only by the antagonist of CB2 receptor; the blockage of the eCB membrane transporter and the depletion of cholesterol failed to reverse the effects of 2-AG. Therefore, this work supports the importance of cannabinoid signalling during cytotrophoblast cell turnover and that its deregulation may be responsible for altered placental development and poor pregnancy outcomes.

Role of ecto-NTPDases on UDP-sensitive P2Y(6) receptor activation during osteogenic differentiation of primary bone marrow stromal cells from postmenopausal women.

This study aimed at investigating the expression and function of uracil nucleotide-sensitive receptors (P2Y(2), P2Y(4), and P2Y(6)) on osteogenic differentiation of human bone marrow stromal cells (BMSCs) in culture. Bone marrow specimens were obtained from postmenopausal female patients (68 ± 5 years old, n = 18) undergoing total hip arthroplasty. UTP and UDP (100 µM) facilitated osteogenic differentiation of the cells measured as increases in alkaline phosphatase (ALP) activity, without affecting cell proliferation. Uracil nucleotides concentration-dependently increased [Ca(2+)](i) in BMSCs; their effects became less evident with time (7 > 21 days) of the cells in culture. Selective activation of P2Y(6) receptors with the stable UDP analog, PSB 0474, mimicked the effects of both UTP and UDP, whereas UTPγS was devoid of effect. Selective blockade of P2Y(6) receptors with MRS 2578 prevented [Ca(2+)](i) rises and osteogenic differentiation caused by UDP at all culture time points. BMSCs are immunoreactive against P2Y(2), P2Y(4), and P2Y(6) receptors. While the expression of P2Y(6) receptors remained fairly constant (7∼21 days), P2Y(2) and P2Y(4) became evident only in less proliferative and more differentiated cultures (7 < 21 days). The rate of extracellular UTP and UDP inactivation was higher in less proliferative and more differentiated cell populations. Immunoreactivity against NTPDase1, -2, and -3 rises as cells differentiate (7 < 21 days). Data show that uracil nucleotides are important regulators of osteogenic cells differentiation predominantly through the activation of UDP-sensitive P2Y(6) receptors coupled to increases in [Ca(2+)](i) . Endogenous actions of uracil nucleotides may be balanced through specific NTPDases determining whether osteoblast progenitors are driven into proliferation or differentiation.

Usefulness of cardiac magnetic resonance imaging for coronary artery disease detection.

Cardiac magnetic resonance imaging (cMRI) is a promising non-invasive technique to assess the presence of coronary artery disease (CAD), which is free of ionizing radiation and iodine contrast. cMRI can detect CAD by angiographic methods or indirectly by perfusion stress techniques. While coronary angiography by cMRI remains limited to research protocols, stress perfusion cMRI is currently being applied worldwide in the clinical setting. Studies have shown good correlation between adenosine-induced stress myocardial perfusion cMRI and single-photon-emission computed tomography or positron emission tomography to detect CAD. Quantitative methods to analyze cMRI perfusion data have been developed in an attempt to provide a more objective imaging interpretation. Standardization of such quantitative methods, with minimal operator dependency, would be useful for clinical and research applications. Myocardial perfusion reserve (MPR), calculated using Fermi deconvolution technique, has been compared with well established anatomical and physiological CAD detection techniques. MPR appears to be the most accurate quantitative index to detect anatomical and hemodynamically significant CAD. Beyond physiological assessment of CAD, cMRI provides information regarding regional and global left ventricular function and morphology, myocardial infarction size, transmurality and viability. Such comprehensive information would require the performance of multiple tests if other modalities were used. This article describes current applications of cMRI for evaluation of patients with CAD.

Successful incorporation of short-interfering RNA into islet cells by in situ perfusion.

UNLABELLED: Islet transplantation offers a potential cure for type I diabetes, although its success has been limited, due to loss of cells by apoptosis stimulated by the procurement, ischemia, and the isolation process itself. RNA interference (RNAi) as mediated by short interfering RNAs (siRNAs) has become a potent tool to manipulate gene expression in mammalian cells. We describe the first successful introduction of siRNA directly into pancreatic islet cells both during in situ perfusion and from intravenous tail vein injection (in vivo). METHODS: siRNA was targeted to the pancreatic islets of BALB/c mice by retrograde portal vein perfusion or tail vein injection. Cy3-labeled siRNA was dissolved in University of Wisconsin (UW) solution at 2 microg/mL. After delivery pancreata were placed in cold storage at 4 degrees C in UW solution for 24 hours, followed by processing for immunofluorescent staining for insulin. Fluorescent imaging was obtained using a Nikon DIAPHOT 300 Inverted Micoscope with a Zeiss AxioCam and OpenLab image capturing software. RESULTS: In situ delivery of siRNA was demonstrated by fluorescent imaging composites of (red) siRNA in and along (green) insulin stained islets from pancreas sections as compared with untreated control sections. The siRNA was detected mainly in and along venous structures throughout the pancreatic tissue. In vivo delivery of siRNA into islets was observed by fluorescent images taken of isolated islets in culture. CONCLUSIONS: We have described the successful delivery of siRNA to pancreatic islets via a novel in situ pancreas perfusion technique and in vivo delivery via tail vein injection.

Saphenous vein graft disease.

Saphenous vein graft (SVG) disease has been an obstinate problem facing the cardiologist since the early days of coronary artery bypass grafting (CABG) surgery. SVG disease follows temporally distinct phases of thrombosis, intimal hyperplasia and progressive atherosclerosis leading to recurrent ischemia which can be treated with repeat operation or percutaneous revascularization. However, repeat operation is associated with high mortality and morbidity. Also, percutaneous treatment of SVG disease is complicated by a high rate of procedural and long term complications due to the interrelated phenomena of distal embolization, slow flow or no reflow, periprocedure myocardial infarction, and subsequent restenosis. Long-term patency is poor in this patient population regardless of the treatment modality. Many pharmaceutical and device based approaches have been tested to avert these complications, but few, such as the use of distal protection devices, have shown benefit. The novel drug-eluting stents show promise in reducing the occurrence of restenosis and solving one of the problems associated with the percutaneous treatment of SVG disease. The pathogenesis and therapeutic options for SVG disease is reviewed in this article.

Analysis of networks based on styrene and divinylbenzene containing iron anchored using variable pressure scanning electron microscopy.

There is great demand for the development of composite materials containing small metal or metal oxides particles, owing to their variable properties and wide application. However, microscopic evaluation of these materials using high-vacuum scanning electron microscopy is difficult because the samples must undergo a series of preparation steps to reach a high image quality and to avoid becoming shrunk inside the microscope vacuum chamber. Thus, in this study, we used variable pressure scanning electron microscopy to evaluate the morphology and iron distribution on the surface of magnetic microspheres based on poly(styrene-co-divinylbenzene). These materials were obtained by suspension copolymerization of styrene and divinylbenzene in the presence of fine iron particles. Energy-dispersive X-rays were also used to analyse distribution of the iron particles. The results indicate that, under the conditions used, magnetic microspheres with a relatively narrow size distribution were formed. Moreover, the micrographs show that agglomerated iron particles appeared only on the microsphere surface.

[Hemophagocytosis associated with an Escherichia coli sepsis: a case report]. / Syndrome d'activation macrophagique associé à une septicémie à Escherichia coli: à propos d'un cas.

INTRODUCTION: Hemophagocytic lymphohistiocytosis syndrome (HLS) is defined by activated macrophage proliferation. These cells phagocyte the blood elements. This syndrome can be primary as an autosomal recessive disease or secondary to neoplasia, immune diseases or infections-viral, parasitary or bacterian. CASE: Our case concerns an association of HLS and Escherichia coli (E. coli) sepsis in a metastatic prostatic cancer. The evolution was rapidly improved by antibiotics alone. The clinical and biological aspects as well as the differential diagnosis are discussed. CONCLUSION: The HLS is fatal. It can be caused by a severe infection, even an E. coli sepsis. The treatment focused on etiology can be sufficient.

Use of rapamycin-impregnated stents in coronary arteries.

FIM STUDY: We investigated the 2-year safety and efficacy of sirolimus-eluting stents. Thirty patients had a single 18-mm sirolimus-eluting coronary stent implanted. Twenty-eight patients underwent angiographic and intravascular ultrasound follow-up at 2 years. No death occurred during the study period. No patient developed in-stent restenosis. One patient had a 52% in-lesion stenosis that required repeated revascularization and another patient underwent target vessel revascularization. Neointimal hyperplasia volume was minimal at 2 years in both groups. This study demonstrates the 2-year safety and efficacy of sirolimus-eluting stenting. The slow release formulation showed slight superiority over the fast-release formulation in preventing late lumen loss, which was minimal in both groups. RAVEL TRIAL: This-study was a randomized, double-blind study that included 238 patients at 19 medical centers (15 in Europe, 3 in Brazil, and 1 in Mexico). Patients were eligible for the study if they were between 18 and 85 years of age, and had been given a diagnosis of stable or unstable angina or silent ischemia. Additional eligibility criteria were presence of a single primary target lesion in a native coronary artery that was 2.5 to 3.5 mm in diameter and that could be covered by an 18-mm stent stenosis of 51% to 99% of the luminal diameter and a flow rate of grade 1 or higher according to the Thrombolysis in Myocardial Infarction. RESULTS: One hundred twenty patients were randomly assigned to receive the sirolimus-eluting stent, and 118 were assigned to receive the standard stent. At 6 months, the degree of neointimal proliferation, manifested as the mean (+/-SD) late luminal loss, was significantly lower in the sirolimus-stent group (-0.01 +/- 0.33 mm) than in the standard-stent group (0.80 +/- 0.53 mm, P <.001). None of the patients in the sirolimus-stent group, as compared with 26.6% of those in the standard-stent group, had restenosis of >/=50% of the luminal diameter (P <.001). There were no episodes of stent thrombosis. During a follow-up period of up to 1 year, the overall rate of major cardiac events was 5.8% in the sirolimus-stent group and 28.8% in the standard-stent group (P <.001). The difference was due entirely to the higher rate of revascularization of the target vessel in the standard-stent group. CONCLUSION: Patients with angina who received sirolimus-eluting stents for the treatment of single, primary lesions in native coronary arteries had no angiographic evidence of late luminal loss or in-stent restenosis at 6 months, no episodes of thrombosis, and a very low rate of cardiac events at 1 year.

Estudo fitoquímico de Erythraea centaurium, Jacaranda caroba, Remijia ferruginea e Solanum paniculatum visando identificar marcadores químicos para o fitoterápico Ierobina®

O fitoterápico Ierobina®, comercializado no mercado nacional há 67 anos, tem uso indicado para o tratamento de dispepsias. O fitoterápico é constituído pelos extratos fluidos de três espécies nativas (Solanum paniculatum, Remijia ferruginea e Jacaranda caroba) e uma exótica (Erythraea centaurium). O presente estudo descreve a identificação de marcadores químicos para os extratos das espécies constituintes da Ierobina® e a obtenção de perfis cromatográficos de referência para os mesmos, os quais contribuirão para o estabelecimento de protocolos para o controle de qualidade do fitoterápico.

Si(3)N(4)-bioglass composites stimulate the proliferation of MG63 osteoblast-like cells and support the osteogenic differentiation of human bone marrow cells.

The in vitro osteocompatibility of a novel Si(3)N(4)-bioglass composite (70-30% weight proportion) with improved mechanical properties (fracture toughness = 4.4 M Pa m(1/2); bending strength = 383 +/- 47 MPa) is reported. Immersion of the composite samples in culture medium (30 min to 7 days) resulted in rapid protein adsorption to the surface and, also, dissolution of the intergranular phase of bioglass (time-dependent process) with the formation of different size cavities. "As-received" and pre-treated material samples presented a similar behaviour concerning the proliferation of MG63 osteoblast-like cells, evaluated during a 5-day culture period. Seeded materials showed a higher cell growth rate as compared to cultures performed on the standard plastic culture plates. To assess the osteogenic potential of the composite, "as-received" material samples were seeded with human bone marrow cells and cultured for 35 days in experimental conditions that favour the development of the osteoblastic phenotype. The cell adhesion process was similar to that observed in control cultures. Cells successfully adapted to the irregularities of the surface and were able to grow towards inside the cavities; in addition, osteogenic differentiation occurred with the formation of abundant cell-mediated mineralised deposits. Results suggest that this Si(3)N(4)-bioglass composite seems to be a promising candidate for high-stress medical applications.