Alginate-nanohydroxyapatite hydrogel system: Optimizing the formulation for enhanced bone regeneration.

Ceramic/polymer-based biocomposites have emerged as potential biomaterials to fill, replace, repair or regenerate injured or diseased bone, due to their outstanding features in terms of biocompatibility, bioactivity, injectability, and biodegradability. However, these properties can be dependent on the amount of ceramic component present in the polymer-based composite. Therefore, in the present study, the influence of nanohydroxyapatite content (30 to 70 wt%) on alginate-based hydrogels was studied in order to evaluate the best formulation for maximizing bone tissue regeneration. The composite system was characterized in terms of physic-chemical properties and biological response, with in vitro cytocompatibility assessment with human osteoblastic cells and ex vivo functional evaluation in embryonic chick segmental bone defects. The main morphological characteristics of the alginate network were not affected by the addition of nanohydroxyapatite. However, physic-chemical features, like water-swelling rate, stability at extreme pH values, apatite formation, and Ca2+ release were nanoHA dose-dependent. Within in vitro cytocompatibility assays it was observed that hydrogels with nanoHA 30% content enhanced osteoblastic cells proliferation and expression of osteogenic transcription factors, while those with higher concentrations (50 and 70%) decreased the osteogenic cell response. Ex vivo data underlined the in vitro findings, revealing an enhanced collagenous deposition, trabecular bone formation and matrix mineralization with Alg-nanoHA30 composition, while compositions with higher nanoHA content induced a diminished bone tissue response. The outcomes of this study indicate that nanohydroxyapatite concentration plays a major role in physic-chemical properties and biological response of the composite system and the optimization of the components ratio must be met to maximize bone tissue regeneration.

Whole-Body Vibration Does Not Seem to Affect Postural Control in Healthy Active Older Women.

OBJECTIVE: This study investigated the acute residual effects induced by different frequencies of whole-body vibration (WBV) on postural control of elderly women. DESIGN: Thirty physically active elderly women (67 ± 5 years) were randomly divided into three groups: two experimental groups (high WBV frequency: 45 Hz and 4 mm amplitude, n = 10; low WBV frequency: 30 Hz and 4 mm amplitude, n = 10) and one control group (n = 10), with no treatment. The participants were first subjected to stabilometry tests and were then guided through three sets of isometric partial squats for 60 s while the WBV stimulation was applied. The control group was subjected to the same conditions but without the WBV stimulation. The participants were again subjected to body balance tests immediately following the end of the intervention period and again at 8, 16, and 24 min. To measure body sway control, three 60 s tests were performed at 10 s intervals for each of the following experimental conditions: (1) eyes opened and (2) eyes closed. The following variables were investigated: the average velocity of the displacement of the centre of pressure in the anterior-posterior and medial-lateral planes as well as in the elliptical area. RESULTS: A 3 (condition) × 5 (test) two-way repeated-measures ANOVA did not identify significant differences in the stabilometric variables, regardless of group, time, or experimental condition. CONCLUSIONS: The effect of WBV, regardless of the stimulation frequency, did not have a significant effect immediately after or up to 24 minutes after vibration cessation, on the variables involved in the control of postural stability in physically active elderly women.

Effect of Sterilization Methods on Electrospun Poly(lactic acid) (PLA) Fiber Alignment for Biomedical Applications.

Medically approved sterility methods should be a major concern when developing a polymeric scaffold, mainly when commercialization is envisaged. In the present work, poly(lactic acid) (PLA) fiber membranes were processed by electrospinning with random and aligned fiber alignment and sterilized under UV, ethylene oxide (EO), and γ-radiation, the most common ones for clinical applications. It was observed that UV light and γ-radiation do not influence fiber morphology or alignment, while electrospun samples treated with EO lead to fiber orientation loss and morphology changing from cylindrical fibers to ribbon-like structures, accompanied to an increase of polymer crystallinity up to 28%. UV light and γ-radiation sterilization methods showed to be less harmful to polymer morphology, without significant changes in polymer thermal and mechanical properties, but a slight increase of polymer wettability was detected, especially for the samples treated with UV radiation. In vitro results indicate that both UV and γ-radiation treatments of PLA membranes allow the adhesion and proliferation of MG 63 osteoblastic cells in a close interaction with the fiber meshes and with a growth pattern highly sensitive to the underlying random or aligned fiber orientation. These results are suggestive of the potential of both γ-radiation sterilized PLA membranes for clinical applications in regenerative medicine, especially those where customized membrane morphology and fiber alignment is an important issue.

Novel cerium doped glass-reinforced hydroxyapatite with antibacterial and osteoconductive properties for bone tissue regeneration.

The aim of this work was to develop a bioactive bone substitute with an effective antibacterial ability based on a cerium (Ce) doped glass-reinforced hydroxyapatite (GR-HA) composite. Developed composites were physicochemically characterized, using x-ray diffraction (XRD) analysis, SEM, energy dispersive x-ray spectroscopy (EDS), and flexural bending strength (FBS) tests. X-ray photoelectron spectroscopy (XPS) analysis was performed to analyze the oxidation state of Ce in the prepared doped glass. The antimicrobial activity of the composites was evaluated against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa; whether the cytocompatibility profile was assayed with human osteoblastic-like cells (Mg-63 cell line). The results revealed that the Ce inclusion in the GR-HA matrix induced the antimicrobial ability of the composite. In addition, Ce-doped materials reported an adequate biological behavior following seeding of osteoblastic populations, by inducing cell adhesion and proliferation. Developed materials were also found to enhance the expression of osteoblastic-related genes. Overall, the developed GR-HA_Ce composite is a prospective candidate to be used within the clinical scenario with a successful performance due to the effective antibacterial properties and capability of enhancing the osteoblastic cell response.

Diels-Alder functionalized carbon nanotubes for bone tissue engineering: in vitro/in vivo biocompatibility and biodegradability.

The risk-benefit balance for carbon nanotubes (CNTs) dictates their clinical fate. To take a step forward at this crossroad it is compulsory to modulate the CNT in vivo biocompatibility and biodegradability via e.g. chemical functionalization. CNT membranes were functionalised combining a Diels-Alder cycloaddition reaction to generate cyclohexene (-C6H10) followed by a mild oxidisation to yield carboxylic acid groups (-COOH). In vitro proliferation and osteogenic differentiation of human osteoblastic cells were maximized on functionalized CNT membranes (p,f-CNTs). The in vivo subcutaneously implanted materials showed a higher biological reactivity, thus inducing a slighter intense inflammatory response compared to non-functionalized CNT membranes (p-CNTs), but still showing a reduced cytotoxicity profile. Moreover, the in vivo biodegradation of CNTs was superior for p,f-CNT membranes, likely mediated by the oxidation-induced myeloperoxidase (MPO) in neutrophil and macrophage inflammatory milieus. This proves the biodegradability faculty of functionalized CNTs, which potentially avoids long-term tissue accumulation and triggering of acute toxicity. On the whole, the proposed Diels-Alder functionalization accounts for the improved CNT biological response in terms of the biocompatibility and biodegradability profiles. Therefore, CNTs can be considered for use in bone tissue engineering without notable toxicological threats.

The Osteogenic Priming of Mesenchymal Stem Cells is Impaired in Experimental Diabetes.

Diabetes mellitus encompasses a group of metabolic conditions embracing the dysfunction and failure of various tissues and organs, including bone. Sustained bone alterations seem to result from anabolic, rather than catabolic processes, and suggest a decreased osteoblastic recruitment and activity. Current knowledge on the cellular and molecular mechanisms were provided by studies performed with osteogenic populations cultured in diabetic-simulated conditions, and osteogenic-induced precursor populations harvested from diabetic animals, sustaining an impaired cellular behavior in terms of osteogenic responsiveness and function. However, the reasons leaning to this impairment remain essentially unknown, as the priming capability and functionality of undifferentiated precursors, developed within the diabetic environment, have not been addressed. Accordingly, this work aims to evaluate the functionality and osteogenic priming capability of bone marrow-derived mesenchymal stem cells (MSCs), harvested from animals with experimental diabetes, and grown in the absence of any given differentiation factor. MSCs developed within a diabetic microenvironment displayed an impaired behavior, with diminished cell viability and proliferation, altered cytoskeleton organization, impaired osteogenic priming, and increased adipogenic activation. Further, the osteogenic induction of diabetic MSCs resulted in an impaired osteogenic commitment. The modified cell phenotype may be related, at least in part, with altered activity of ERK WNT and p38 signaling pathways in diabetic-derived cultures. Specific strategies, aiming the modulation of the verified hindrances, may be of therapeutic value to enhance the functionality of diabetic MSCs and sustain an improved outcome in the metabolism and regeneration of the bone tissue in diabetic conditions.

Multifunctional carbon nanotube/bioceramics modulate the directional growth and activity of osteoblastic cells.

Biomaterials can still be reinvented to become simple and universal bone regeneration solutions. Following this roadmap, a bone graft of carbon nanotube (CNT)/glass/hydroxyapatite (HA) with controlled CNT agglomeration state was designed with multifunctionalities able to stimulate the bone cell phenotype. The preparation route, the mechanical and electrical behavior and the in vitro profiles of degradation and osteocompatibility were described. A non-destructive dynamic route was found to have a higher influence than the Diels-Alder functionalization one on controlling the CNT agglomerate state in the ceramic-matrix composite. Biologically safe CNT agglomerates, with diameter sizes below 3 microm homogenously distributed, were obtained in non-functionalized and functionalized composites. Yet, the lowest CNT damage and the highest mechanical and electrical properties were found for the non-functionalized materials. Even though that these composites present higher degradation rate at pH:3 than the ceramic matrix, the CNT agglomerates are released with safe diameter sizes. Also, non-functionalized composites allowed cellular adhesion and modulated the orientation of the cell growth, with a proliferation/differentiation relationship favoring osteoblastic functional activity. Findings offer further contributions for bone tissue engineering by showing that multifunctional bone grafts with high electroconductivity, and integrating CNT agglomerates with maximized interfacing area, allow the in situ control of bone cell functions.

Processing strategies for smart electroconductive carbon nanotube-based bioceramic bone grafts.

Electroconductive bone grafts have been designed to control bone regeneration. Contrary to polymeric matrices, the translation of the carbon nanotube (CNT) electroconductivity into oxide ceramics is challenging due to the CNT oxidation during sintering. Sintering strategies involving reactive-bed pressureless sintering (RB + P) and hot-pressing (HP) were optimized towards prevention of CNT oxidation in glass/hydroxyapatite (HA) matrices. Both showed CNT retentions up to 80%, even at 1300 °C, yielding an increase of the electroconductivity in ten orders of magnitude relative to the matrix. The RB + P CNT compacts showed higher electroconductivity by ∼170% than the HP ones due to the lower damage to CNTs of the former route. Even so, highly reproducible conductivities with statistical variation below 5% and dense compacts up to 96% were only obtained by HP. The hot-pressed CNT compacts possessed no acute toxicity in a human osteoblastic cell line. A normal cellular adhesion and a marked orientation of the cell growth were observed over the CNT composites, with a proliferation/differentiation relationship favouring osteoblastic functional activity. These sintering strategies offer new insights into the sintering of electroconductive CNT containing bioactive ceramics with unlimited geometries for electrotherapy of the bone tissue.

The biomaterial-mediated healing of critical size bone defects in the ovariectomized rat.

UNLABELLED: This study demonstrated an impaired biomaterial-mediated bone regeneration in a critical sized calvarial defect established within an ovariectomized rat model. Histological and microtomographic evidences were supported by an impaired osteoblastic gene expression and altered expression of estrogen receptors and adipogenic markers. INTRODUCTION: This work aims to address the bone regeneration process in the ovariectomized rat model, by assessing a calvarial critical size defect implanted with a biocompatible bovine bone mineral graft. METHODS: Animals were randomly divided into two groups: Ovx (bilateral ovariectomy) and Sham (control surgery). Following 8 weeks, all animals were submitted to a surgical bicortical craniotomy (5-mm circular critical size defect), which was filled with a biocompatible mineral graft. Animals were euthanized at 1, 3, and 6 months following graft implantation (n = 10), and results on the orthotopic bone regeneration process were blindly evaluated by radiographic, microtomographic, histological, histomorphometric, and gene expression techniques. RESULTS: In the attained model, in both Sham and Ovx groups, the bone regenerative process was found to occur in a slow-paced manner. Likewise, a qualitative evaluation of the microtomographic and histological analysis, as well as quantitative data from histomorphometric indexes, revealed reduced bone regeneration in Ovx animals, at the assayed time points. Significant differences were attained at the 3 and 6 months. Gene expression analysis revealed a reduced expression of osteoblastic-related genes and an altered expression of estrogen receptors and adipogenic markers, within the regenerating bone of Ovx animals. CONCLUSIONS: Due to the similarities between the osteoporotic animal model and the human condition of postmenopausal osteoporosis, it might be relevant to consider the potential clinical implication of the osteoporotic condition in the biomaterial-mediated bone tissue healing/regeneration process.

Taxas de perda gestacional até 60 dias são afetadas por características cíclicas da égua receptora de embrião Mangalarga Marchador / Rates of pregnancy loss up to 60 days are affected by cyclic characteristics of the Mangalarga Marchador recipient mare

Foram avaliadas taxas de gestação aos 15 dias e perda gestacional entre 15 e 60 dias em 430 transferências de embrião (TE) em éguas Mangalarga Marchador. Diagnósticos de gestação foram realizados entre 15 e 60 dias após TE. Para avaliar os efeitos da duração da fase folicular da receptora, foram formados três grupos: até três dias (<3d); quatro a seis dias (4-6d); sete ou mais dias (>7d). Para avaliar os efeitos do tamanho do folículo pré-ovulatório da receptora, foram formados outros três grupos: menor ou igual a 35mm (Ø<35); maior que 35 e menor ou igual a 45mm (35<Ø<45); maior que 45mm (Ø>45). Os grupos foram comparados pelo teste qui-quadrado (P<0,05). Quanto à duração da fase folicular, as taxas de gestação foram semelhantes (<3d - 83,1%; 4-6d - 86,4%; >d - 86,0%), e a perda gestacional maior em >7d (24,4%) que em <3d(12,0%) e 4-6d (13,3%), estas semelhantes entre si. Quanto ao tamanho folicular, as taxas de gestação foram semelhantes (Ø<35 - 86,4%; 35<Ø<45 - 86,5%; Ø>45 - 81,9%), assim como as de perda gestacional (Ø<35 - 13,2%; 35<Ø<45 - 18,1%; Ø>45 - 10,5%). Razões para a maior perda gestacional no grupo >7dnão foram esclarecidas, mas conclui-se que a duração da fase folicular pode ser fator de escolha de receptoras.

Pregnancy rates were evaluated at 15 days and pregnancy loss between 15 and 60 days on 430 embryo transfers (ET) in Mangalarga Marchador mares. Pregnancy diagnosis was performed between 15 and 60 days after ET. To evaluate the effects of the duration of the follicular phase of the recipient mare, three groups were formed: up to 3 days (<3d); 4 to 6 days (4-6d); 7 or more days (>7d). To evaluate the effects of the size of the pre-ovulatory follicle of the recipient mare, three other groups were formed: below or equal to 35mm (Ø<35); greater than 35 and below or equal to 45mm (35<Ø<45); greater than 45mm (Ø>45). The groups were compared by Chi-square test (P<0.05). Regarding the duration of the follicular phase, pregnancy rates were similar (<3d - 83.1%; 4-6d - 86.4%; >7d - 86.0%), and greater pregnancy loss in >7d (24.4%) than in <3d (12.0%) and 4-6d (13.3%), which were similar. Regarding the follicle size, pregnancy rates (Ø<35 - 86.4%; 35<Ø<45 - 86.5%; Ø>45 - 81.9%) and pregnancy loss (Ø<35 - 13.2%; 35<Ø<45 - 18.1%; Ø>45 - 10.5%) were similar. Reasons for the greatest pregnancy loss in the >7d group have not been elucidated, but we conclude that the duration of the follicular phase may be a factor for choosing recipient mares.

Relevance of the sterilization-induced effects on the properties of different hydroxyapatite nanoparticles and assessment of the osteoblastic cell response.

Hydroxyapatite (Hap) is a calcium phosphate with a chemical formula that closely resembles that of the mineral constituents found in hard tissues, thereby explaining its natural biocompatibility and wide biomedical use. Nanostructured Hap materials appear to present a good performance in bone tissue applications because of their ability to mimic the dimensions of bone components. However, bone cell response to individual nanoparticles and/or nanoparticle aggregates lost from these materials is largely unknown and shows great variability. This work addresses the preparation and characterization of two different Hap nanoparticles and their interaction with osteoblastic cells. Hap particles were produced by a wet chemical synthesis (WCS) at 37°C and by hydrothermal synthesis (HS) at 180°C. As the ultimate in vivo applications require a sterilization step, the synthesized particles were characterized 'as prepared' and after sterilization (autoclaving, 120°C, 20 min). WCS and HS particles differ in their morphological (size and shape) and physicochemical properties. The sterilization modified markedly the shape, size and aggregation state of WCS nanoparticles. Both particles were readily internalized by osteoblastic cells by endocytosis, and showed a low intracellular dissolution rate. Concentrations of WCS and HS particles less than 500 µg ml(-1) did not affect cell proliferation, F-actin cytoskeleton organization and apoptosis rate and increased the gene expression of alkaline phosphatase and BMP-2. The two particles presented some differences in the elicited cell response. In conclusion, WCS and HS particles might exhibit an interesting profile for bone tissue applications. Results suggest the relevance of a proper particle characterization, and the interest of an individual nanoparticle targeted research.

Equisetum arvense hydromethanolic extracts in bone tissue regeneration: in vitro osteoblastic modulation and antibacterial activity.

OBJECTIVES: Equisetum arvense preparations have long been used to promote bone healing. The aim of this work was to evaluate osteogenic and antibacterial effects of E. arvense hydromethanolic extracts. MATERIALS AND METHODS: Dried aerial components of E. arvense were extracted using a mixture of methanol:water (1:1), for 26 days, yielding three extracts that were tested (10-1000 µg/ml) in human osteoblastic cells: E1, E2 and EM (a mixture of E1 and E2, 1:1). Cell cultures, performed on cell culture plates or over hydroxyapatite (HA) substrates, were assessed for osteoblastic markers. In addition, effects of the extracts on Staphylococcus aureus were addressed. RESULTS: Solution E1 caused increased viability/proliferation and ALP activity at 50-500 µg/ml, and deleterious effects at levels ≥1000 µg/ml. E2 inhibited cell proliferation at levels ≥500 µg/ml. EM presented a profile between those observed with E1 and E2. In addition, E1, E2 and EM, 10-1000 µg/ml, inhibited expansion of S. aureus. Furthermore, E1, tested in HA substrates colonized with osteoblastic cells, causing increase in cell population growth (10-100 µg/ml). E1 also exhibited antibacterial activity against S. aureus cultured over HA. CONCLUSIONS: Results showed that E. arvense extracts elicited inductive effects on human osteoblasts while inhibiting activity of S. aureus, suggesting a potentially interesting profile regarding bone regeneration strategies.

Silicate and borate glasses as composite fillers: a bioactivity and biocompatibility study.

Composites filled with a silicate glass (CSi) and a new borate glass (CB) were developed and compared in terms of their in vitro behaviour both in acellular and cellular media. Acellular tests were carried out in SBF and the composites were characterized by SEM-EDS, XRD and ICP. Biocompatibility studies were investigated by in vitro cell culture with MG-63 osteoblast-like and human bone marrow cells. The growth of spherical calcium phosphate aggregates was observed in acellular medium on all composite surfaces indicating that these materials became potentially bioactive. The biological assessment resulted in a dissimilar behavior of the composites. The CSi demonstrated an inductive effect on the proliferation of cells. The cells showed a normal morphology and high growth rate when compared to standard culture plates. Contrarily, inhibition of cell proliferation occurred in the CB probably due to its high degradation rate, leading to high B and Mg ionic concentration in the cell culture medium.

Mastocytosis: oral implications of a rare disease.

Mastocytosis encompasses a group of rare clinical entities, which are characterized by an abnormal growth and, usually, low accumulation of clonal and morphologically abnormal mast cells (MCs), within one or more organs. Clinical presentations are quite variable and symptoms are usually related to the release of mast cell mediators, tissue infiltration by MC (usually in the aggressive categories of the disease), or both. Mast cells are hematopoietic-derived cells that reach phenotypic maturity in the mucosa and peripheral connective tissues. These cells play an active role both on immunologic and non-immunologic processes. Within the oral cavity, MCs reside in the connective tissues, in physiologic conditions, and their number is elevated in pathologic situations resulting from immunoinflammatory processes, such as pulpal inflammation and periodontal disease. As MCs influence so many phenomena within the oral cavity, mastocytosis may manifest itself in the oral tissues. Patients with mastocytosis should be put under special care by dental professionals, in what concerns not only general patient management, but also drug prescription, as they are particularly prone to anaphylaxis and other peri and post-operative complications. Several allergens or mast cell activation triggers such as local anesthetics, zinc oxide, eugenol, penicilins, metals and oral hygiene products are frequently administered or prescribed by dentists. Patients with mastocytosis may also require stress management, during dental consultation. This review aims to briefly summarize the potential ways in which mast cell disease may affect the oral cavity and the dental management of mastocytosis affected patients.

Rodent models in bone-related research: the relevance of calvarial defects in the assessment of bone regeneration strategies.

In vivo research with animal models has been a preferred experimental system in bone-related biomedical research since, by approximation, it allows relevant data gathering regarding physiological and pathological conditions that could be of use to establish more effective clinical interventions. Animal models, and more specifically rodent models, have been extensively used and have contributed greatly to the development and establishment of a wide range of translational approaches aiming to regenerate the bone tissue. In this regard, the calvarial defect model has found great application in basic and applied research, nonetheless the controversial rationalization for the use of critical size defects - defects that are unable to report spontaneous healing - or subcritical size defects in the proposed applications. Accordingly, this work aims to review the advantages and limitations of the use of rodent models in biomedical bone-related research, emphasizing the problematic issues of the use of calvarial critical and subcritical size defects. Additionally, surgical protocols for the establishment of both defects in rat calvarial bone, as well as the description and exemplification of the most frequently used techniques to access the bone tissue repair, are portrayed.

New titanium and titanium/hydroxyapatite coatings on ultra-high-molecular-weight polyethylene-in vitro osteoblastic performance.

The development of optimized hip joint materials is one of the most challenging opportunities in prosthetic technologies. In current approaches, ultra-high-molecular-weight polyethylene(UHMWPE) has been a favorite material for the acetabular component and, regarding the cementless technique, several coating options may be considered to contain and stabilize bearing surfaces and establish an improved interface with bone. In this work, newly developed constructs of UHMWPE coated with either commercially pure titanium (cpTi-UHMWPE), by DC magnetron sputtering, or with commercially pure titanium and hydroxyapatite(cpTi/HA-UHMWPE), by DC/RF magnetron co-sputtering, have been prepared and biologically characterized with human bone marrow-derived osteoblastic cultures. The cpTi-UHMWPE samples allowed a high cell growth and the expression of the complete osteoblastic phenotype, with high alkaline phosphatase activity, expression of osteogenic-associated genes and evident cell-mediated mineralization of the extracellular matrix. In comparison, the cpTi/HA-UHMWPE samples reported lower cell proliferation but earlier cell-mediated matrix mineralization. Accordingly, these newly developed systems maybe suitable candidates to improve the osteointegration process in arthroplastic devices;nevertheless, further biological evaluation should be conducted.

Effects of short-term very low-carbohydrate or conventional diet on strength performance.

AIM: Weight reduction strategies usually include diet and regular physical activity. A very low-carbohydrate and high protein diet (VLCD) may be preferred instead of a low energy conventional diet (CONV). The effects of VLCD on strength performance are yet to be understood. Aim of the study is to determine the effects of two different restrictive diets on strength performance. METHODS: Sedentary women were assigned to either a VLCD (<40 g carbohydrate; n=12) or a CONV diet (500 to 800 kcal restrictive; 48%, 22% and 30% from carbohydrate, protein and fat, respectively; n=12). Knee extension isokinetic strength tests (3 yen 15 reps at 60 degrees .s-1, with 90 or 180 s rest interval between sets) were performed prior and after a one week diet period. RESULTS: Both groups reduced body mass (VLCD: -2.6+/-1.0% vs. CONV: -1.9+/-1.3%; P<0.05), with no between diets effect. The sum of the total work in three sets (ATW) was 4850+/-1002 J vs. 4801+/-973 J with 90 s rest interval, and 4812+/-1174 J vs. 4812+/-1210 J with 180 s rest interval, respectively, in the pre vs. post-VLCD period. For CONV, values were 4709+/-729 J vs. 4530+/-996 J with 90 s rest interval, and 4760+/-732 J vs. 4816+/-702 J with 180 s rest interval, respectively, in the pre vs. post-CONV treatment. No significant differences were detected in the ATW between groups. CONCLUSION: Short-term hypoenergetic diets, irrespective of the carbohydrate content, seem to reduce significantly body mass, but do not impair acute strength performance.

Cytotoxicity evaluation of nanocrystalline diamond coatings by fibroblast cell cultures.

The cytotoxicity profile of nanocrystalline diamond (NCD) coatings on a Si(3)N(4) ceramic was investigated. This material is envisaged to have biomedical dental applications such as burrs and surgical instruments. Two fibroblast cell culture systems were used to address the cytotoxicity of NCD-coated samples: L929 cells (a mouse permanent cell line) and human gingival fibroblasts. Cell behavior was evaluated in terms of cell adhesion, cell viability/proliferation (mitochondrial function, MTT assay) and the pattern of cell growth. Fibroblast cell behavior on standard polystyrene culture plates was used as control, as Si(3)N(4) substrates have previously been shown to be biocompatible. NCD coatings provided a suitable surface for cell attachment, spreading and proliferation. Human gingival cells showed a homogeneous cytoplasm spreading, a flattened elongated morphology and a typical parallel alignment on confluent cultures. In comparison, L929 cells denoted a lower cytoplasm expansion, a heterogeneous spreading but a higher proliferation rate. For both cells, after few days, the NCD coating was completely covered with continuous cell layers. As compared to standard polystyrene culture plates, no deleterious or cytotoxic responses were observed with L929 and human fibroblast cell cultures, and in both a slight enhancement in cell proliferation was observed. In addition, the seeded NCD film allowed reproduction of the typical features of the two cell culture systems tested, further suggesting the lack of cytotoxicity of this coating.

Growth and phenotypic expression of human endothelial cells cultured on a glass-reinforced hydroxyapatite.

Glass-reinforced hydroxyapatite composites (GR-HA) are bone regenerative materials that are characterized by their increased mechanical properties, when compared to synthetic hydroxyapatite. Bonelike is a GR-HA that is a result of the addition of a CaO-P(2)O(5) based glass to a HA matrix. This biomaterial has been successfully applied in clinical bone regenerative applications. This work aims to evaluate the ability of Bonelike to support the adhesion, proliferation and phenotypic expression of human endothelial cells, aiming to establish new bone tissue engineering pre-endothelialization strategies. Bonelike discs, regardless of being submitted to a pre-immersion treatment with culture medium, were seeded with first passage human umbilical vein endothelial cells, and characterized regarding proliferation and differentiation events. Pre-immersed Bonelike allowed the adhesion, proliferation and phenotype expression of endothelial cells. Seeded materials presented positive immunofluorescent staining for PECAM-1 and a tendency for the formation of cord-like arrangements under angiogenesis-stimulating conditions, although, compared to standard culture plates, a slight decreased cell growth was observed. In this way, Bonelike may be a suitable candidate for pre-endothelialization approaches in bone tissue engineering applications.