Treatment de-escalation in HPV-positive oropharyngeal carcinoma: ongoing trials, critical issues and perspectives

Due to the generally poor prognosis of head and neck squamous cell carcinoma (HNSCC), treatment has been intensified, these last decades, leading to an increase of serious side effects. High-risk human papillomavirus (HR-HPV) infection has been recently etiologically linked to a subset of oropharyngeal squamous cell carcinoma (OPSCC), which is on the increase. These tumors are different, at the clinical and molecular level, when compared to tumors caused by traditional risk factors. Additionally, their prognosis is much more favorable which has led the medical community to consider new treatment strategies. Indeed, it is possible that less intensive treatment regimens could achieve similar efficacy with less toxicity and improved quality of life. Several clinical trials, investigating different ways to de-escalate treatment, are currently ongoing. In this article, we review these main approaches, discuss the rationale behind them and the issues raised by treatment de-escalation in HPV-positive OPSCC.

Stress Induction of Mitochondrial Formate Dehydrogenase in Potato Leaves

In higher plants formate dehydrogenase (FDH, EC 1.2.1.2.) is a mitochondrial, NAD-dependent enzyme. We previously reported that in potato (Solanum tuberosum L.) FDH expression is high in tubers but low in green leaves. Here we show that in isolated tuber mitochondria FDH is involved in formate-dependent O2 uptake coupled to ATP synthesis. The effects of various environmental and chemical factors on FDH expression in leaves were tested using the mitochondrial serine hydroxymethyltransferase as a control. The abundance of FDH transcripts is strongly increased under various stresses, whereas serine hydroxymethyltransferase transcripts decline. The application of formate to leaves strongly enhances FDH expression, suggesting that it might be the signal for FDH induction. Our experiments using glycolytic products suggest that glycolysis may play an important role in formate synthesis in leaves in the dark and during hypoxia, and in tubers. Of particular interest is the dramatic accumulation of FDH transcripts after spraying methanol on leaves, as this compound is known to increase the yields of C3 plants. In addition, although the steady-state levels of FDH transcript increase very quickly in response to stress, protein accumulation is much slower, but can eventually reach the same levels in leaves as in tubers.

Relationship of free intracellular calcium to the cytolytic activity of Entamoeba histolytica

Entamoeba histolytica adherence and destruction of host cells is required for in vivo pathogenicity; amebic in vitro adherence is mediated by a galactose- or N-acetyl-D-galactosamine-inhibitable surface lectin (Gal/GalNAc adherence lectin). Free intracellular Ca2+ concentration [( Ca2+]i) was measured in living amebae and target cells during amebic cytolysis of Chinese hamster ovary (CHO) cells and human polymorphonuclear neutrophils by utilizing the Ca2+ probe Fura-2 and computer-enhanced digitized microscopy. Motile E. histolytica trophozoites had oscillatory increases in [Ca2+]i in head or tail regions; however, there was no increase in regional or total amebic [Ca2+]i upon contact with a target CHO cell. Target CHO cells and polymorphonuclear neutrophils demonstrated marked irreversible increases in [Ca2+]i within 30 to 300 s following contact by an ameba (P less than 0.01); increased [Ca2+]i preceded the occurrence of nonspecific surface membrane permeability and death of the target cell. Target CHO cells contiguous on a monolayer to a cell contacted by an ameba experienced a rapid but reversible rise in [Ca2+]i (P less than 0.01) and were not killed. Galactose (40 mg/ml) totally abrogated the rise in target CHO cell [Ca2+]i that followed contact by amebae (P less than 0.01); immunoaffinity-purified amebic Gal/GalNAc adherence lectin (0.25 micrograms/ml) induced a rapid and reversible rise in CHO cell [Ca2+]i (P less than 0.01) which was inhibited by galactose. Amebic [Ca2+]i was not elevated following parasite adherence to target cells; a rapid and substantial rise in target cell [Ca2+]i occurred which was mediated, at least in part, by the Gal/GalNAc adherence lectin of the parasite and led to the death of target cells.

Indication of electron neutrino appearance from an accelerator-produced off-axis muon neutrino beam

The T2K experiment observes indications of ν(μ) → ν(e) appearance in data accumulated with 1.43×10(20) protons on target. Six events pass all selection criteria at the far detector. In a three-flavor neutrino oscillation scenario with |Δm(23)(2)| = 2.4×10(-3)  eV(2), sin(2)2θ(23) = 1 and sin(2)2θ(13) = 0, the expected number of such events is 1.5±0.3(syst). Under this hypothesis, the probability to observe six or more candidate events is 7×10(-3), equivalent to 2.5σ significance. At 90% C.L., the data are consistent with 0.03(0.04) < sin(2)2θ(13) < 0.28(0.34) for δ(CP) = 0 and a normal (inverted) hierarchy.

The MUT056399 inhibitor of FabI is a new antistaphylococcal compound

MUT056399 is a highly potent new inhibitor of the FabI enzyme of both Staphylococcus aureus and Escherichia coli. In vitro, MUT056399 was very active against S. aureus strains, including methicillin-susceptible S. aureus (MSSA), methicillin-resistant S. aureus (MRSA), linezolid-resistant, and multidrug-resistant strains, with MIC(90)s between 0.03 and 0.12 μg/ml. MUT056399 was also active against coagulase-negative staphylococci, with MIC(90)s between 0.12 and 4 μg/ml. The antibacterial spectrum is consistent with specific FabI inhibition with no activity against bacteria using FabK but activity against FabI-containing Gram-negative bacilli. In vitro, resistant clones of S. aureus were obtained at a low frequency. All of the resistant clones analyzed were found to contain mutations in the fabI gene. In vivo, MUT056399, administered subcutaneously, protected mice from a lethal systemic infection induced by MSSA, MRSA, and vancomycin-intermediate S. aureus strains (50% effective doses ranging from 19.3 mg/kg/day to 49.6 mg/kg/day). In the nonneutropenic murine thigh infection model, the same treatment with MUT056399 reduced the bacterial multiplication of MSSA and MRSA in the thighs of immunocompetent mice. These properties support MUT056399 as a very promising candidate for a novel drug to treat severe staphylococcal infections.

Obstructive sleep apnoea in people with Type 1 diabetes: prevalence and association with micro- and macrovascular complications

AIMS

Few reports have assessed the relationship between Type 1 diabetes and sleep disorders. The purposes of our study were to determine the prevalence of obstructive sleep apnoea in Type 1 diabetes and to compare the clinical profile of people with Type 1 diabetes with or without obstructive sleep apnoea.

METHODS

In this cross sectional study of 67 consecutive people with Type 1 diabetes, we performed polysomnography as part of their yearly check-ups.

RESULTS

In our cohort, with a mean BMI of 25.8 ± 4.7 kg/m(2), the prevalence of obstructive sleep apnoea [apnoea-hypopnoea index (AHI) > 10/h] was 46%. Severe obstructive sleep apnoea (AHI ≥ 30/h) was present in 19% of the patients. We found no significant differences in age, sex, body mass index, HbA1c or Epworth sleepiness scale score between people with or without obstructive sleep apnoea. People with obstructive sleep apnoea had a longer course of diabetes mellitus (P < 0.01) and a higher prevalence of retinopathy (P < 0.01), neuropathy (P = 0.05), cardiovascular disease (P < 0.01) and hypertension (P < 0.01). The occurrence of macrovascular complications was independently associated with the presence of OSA [odds ratio (OR) 8.28; 95% confidence interval (CI), 1.56-43.97; P = 0.013] and the duration of diabetes (OR 1.08; 95% CI, 1.02-1.15; P = 0.01). Moreover, retinopathy was independently associated with OSA (OR 4.54; 95% CI, 1.09-18.82; P = 0.04) and the duration of diabetes (OR 1.09; 95% CI, 1.04-1.15; P = 0.001).

CONCLUSIONS

The prevalence of obstructive sleep apnoea was high in people with Type 1 diabetes. Obstructive sleep apnoea was independently associated with macrovascular complications and retinopathy. Obesity and excessive daytime sleepiness were uncommon in this population.

Discovery of new Gram-negative antivirulence drugs: structure and properties of novel E. coli WaaC inhibitors

Heptosyltransferases such as WaaC represent promising and attractive targets for the discovery of new Gram-negative antibacterial drugs based on antivirulence mechanisms. We report herein our approach to the identification of the first micromolar inhibitors of WaaC and the preliminary SAR generated from this family of 2-aryl-5-methyl-4-(5-aryl-furan-2-yl-methylene)-2,4-dihydro-pyrazol-3-ones identified by virtual screening.

Bone tissue formation in sheep muscles induced by a biphasic calcium phosphate ceramic and fibrin glue composite

Some biomaterials are able to induce ectopic bone formation in muscles of large animals. The osteoinductive potential of macro- micro-porous biphasic calcium phosphate (MBCP) ceramic granules with fibrin glue was evaluated by intramuscular implantation for 6 months in six adult female sheep. The MBCP granules were 1-2 mm in size and were composed of hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) in a 60/40 ratio. The fibrin glue was composed of fibrinogen, thrombin and other biological factors. After 6 months of implantation in the dorsal muscles of sheep, the explants were rigid. Histology, back-scattered electron microscopy and micro-computed tomography of the implants indicated that approximately 12% of mineralized bone had formed in between the MBCP granules. The ectopic bone appeared well-mineralized with mature osteocytes and Haversian structures. In addition, the number and thickness of bone trabeculae formed in between the MBCP particles were similar to those measured in trabecular bone in sheep. The overall results therefore confirmed the formation of well-mineralized ectopic bone tissue after intramuscular implantation of MBCP/fibrin glue composites. These bone substitutes exhibiting osteoinductive properties could be used for the reconstruction of large bone defects.

Oropharyngeal cancers: relationship between epidermal growth factor receptor alterations and human papillomavirus status

High-risk human papillomavirus (HR-HPV), particularly type 16, is now recognised as a causative agent in a subset of oropharyngeal squamous cell carcinomas (OPSCCs). These tumours are on the increase and generally have a better prognosis than their HPV negative counterparts. This raises the question of de escalation therapy to reduce long term consequences in a younger cohort of patients with a long life expectancy. Several clinical trials with anti-epidermal growth factor receptor (EGFR) therapies, particularly cetuximab, are ongoing. Few data exist on the relationship between EGFR and HPV induced oropharyngeal cancers. We summarise the main studies in relation to EGFR alterations (gene copy number, protein expression and mutations) and the impact on prognosis of HPV positive tumours that express high levels of EGFR. We also discuss the opportunity of targeting this pathway in light of recent studies.

Continuous glucose monitoring in cystic fibrosis patients according to the glucose tolerance

Cystic fibrosis (CF) is associated with a long preclinical state of abnormal glucose tolerance. The aim of this study was (i) to evaluate the profile of glucose tolerance in young adults with CF and (ii) to compare these results with those obtained by a continuous subcutaneous glucose monitoring (CGMS). CF subjects with fasting glycemia inferior to 126 mg/dl were included in the study. An oral glucose tolerance test (OGTT) identified the subjects either with a normal glucose tolerance (NGT), or impaired glucose tolerance (IGT), or diabetes. CGMS (Medtronic) was performed during 3 days to analyze mean glucose level, high glucose excursions, and glucose area under the curve (AUC). Forty-nine patients were included in the study. NGT (n=22), IGT (n=17), and diabetes groups (n=10) were comparable except with regard to age and BMI (p<0.001). HbA1c values in diabetes group were significantly higher (p<0.001) than in NGT and IGT groups. CGMS revealed peaks of glucose values superior to 200 mg/dl at least once after a meal in 8 patients (36%) with NGT, in 9 patients (52%) with IGT, and in all patients with diabetes (p<0.01). Mean CGMS glucose and glucose AUC values increased in patients with diabetes compared to patients with NGT and IGT (p<0.05). Peak of CGMS glucose reached 182+/-60 mg/dl in NGT group despite the normal glucose profile at OGTT. In conclusion, CGMS revealed pathological glucose excursions not only in patients with impaired glucose tolerance at OGTT but also in patients with a normal glycemic profile. CGMS could be a useful tool for the early detection of hyperglycemia in patients with CF.

Evaluation of humoral response and protective efficacy of two inactivated vaccines against bluetongue virus after vaccination of goats

Bluetongue serotype 8 has become a major animal health issue in the European Union and the European member States have agreed on a vaccination strategy, which involves only inactivated vaccines. In this study, the efficacy of two inactivated vaccines against bluetongue virus serotype 8 (BTV-8) used in Europe since 2008, BTVPUR ALSAP(®) 8 (MERIAL) and BOVILIS(®) BTV8 (Intervet/SP-AH), was evaluated in goats immunized and challenged with BTV-8 field isolates under experimental conditions. Serological, virological and clinical examinations were conducted before and after challenge. Three groups of 10 goats each (groups A, B and C) were randomly constituted and 2 groups (A and C) were subcutaneously vaccinated twice with one dose of the two commercial vaccines BTVPUR ALSAP 8 (group A) or BOVILIS BTV8 (group C) respectively. Animals of the groups A, C and B (B: controls) were challenged with a virulent inoculum containing BTV-8. During the experiment, it was found out that the BTV-8 challenge inoculum was contaminated with another BTV serotype. However, results demonstrated that vaccination of goats with two injections of BTVPUR ALSAP 8 or BOVILIS BTV8 provided a significant clinical protection against a BTV-8 challenge and completely prevented BTV-8 viraemia in all vaccinated animals. Qualitative data showed no difference in the kinetics and levels of the humoral response induced by these two inactivated vaccines.

Telemedicine and type 1 diabetes: is technology per se sufficient to improve glycaemic control?

AIM

In the TELEDIAB-1 study, the Diabeo system (a smartphone coupled to a website) improved HbA1c by 0.9% vs controls in patients with chronic, poorly controlled type 1 diabetes. The system provided two main functions: automated advice on the insulin doses required; and remote monitoring by teleconsultation. The question is: how much did each function contribute to the improvement in HbA1c?

METHODS

Each patient received a smartphone with an insulin dose advisor (IDA) and with (G3 group) or without (G2 group) the telemonitoring/teleconsultation function. Patients were classified as "high users" if the proportion of "informed" meals using the IDA exceeded 67% (median) and as "low users" if not. Also analyzed was the respective impact of the IDA function and teleconsultations on the final HbA1c levels.

RESULTS

Among the high users, the proportion of informed meals remained stable from baseline to the end of the study 6months later (from 78.1±21.5% to 73.8±25.1%; P=0.107), but decreased in the low users (from 36.6±29.4% to 26.7±28.4%; P=0.005). As expected, HbA1c improved in high users from 8.7% [range: 8.3-9.2%] to 8.2% [range: 7.8-8.7%] in patients with (n=26) vs without (n=30) the benefit of telemonitoring/teleconsultation (-0.49±0.60% vs -0.52±0.73%, respectively; P=0.879). However, although HbA1c also improved in low users from 9.0% [8.5-10.1] to 8.5% [7.9-9.6], those receiving support via teleconsultation tended to show greater improvement than the others (-0.93±0.97 vs -0.46±1.05, respectively; P=0.084).

CONCLUSION

The Diabeo system improved glycaemic control in both high and low users who avidly used the IDA function, while the greatest improvement was seen in the low users who had the motivational support of teleconsultations.

Stable expression of functional mitochondrial uncoupling protein in Chinese hamster ovary cells

The mitochondrial uncoupling protein (UCP) is a membranous proton carrier exclusively synthesized in brown adipocytes. The cDNA for the rat UCP was placed in an expression vector and transfected into mammalian cells. Its expression was tested in transiently transfected CHO cells. In these cells the UCP was detected in mitochondria by using antibodies. Permanent expression of the UCP was achieved in stable transformed CHO cell lines. In these cells the UCP was characterized in mitochondrial membranes, by using antibodies and hydroxyapatite purification. The protein expressed in CHO cells displayed the functional characteristics of brown adipocyte UCP. It induced the uncoupling of respiration in isolated CHO mitochondria. The membrane potential of transformed mitochondria was also significantly lowered, as a result of the proton translocating activity of the UCP. GDP is known to inhibit the proton pathway in brown fat mitochondria. Addition of GDP to CHO mitochondria containing UCP resulted in a recoupling of respiration and an increase in membrane potential. Thus we conclude that functional UCP is expressed in CHO cells and that the insertion of the UCP alone in any mitochondria is sufficient to induce the uncoupling of respiration. This approach should allow studies on the structure-function relationship of the UCP and of several other related mitochondrial carriers.

Protonophoric activity of ellipticine and isomers across the energy-transducing membrane of mitochondria

Ellipticine is an antitumor alkaloid capable of uncoupling mitochondrial oxidative phosphorylation. It behaves as a lipophilic weak base with pK = 7.40. We have investigated its molecular mode of action using several of its isomers with pK ranging between 5.8 and 7.7 and ellipticinium, which is a permanent cationic derivative. The effects of these molecules on mitochondrial oxygen uptake and transmembrane potential were compared at different pHs. Ellipticinium exhibited very low effects on both respiratory rate and membrane potential. By contrast, protonable derivatives showed maximal stimulation of oxygen uptake and depolarizing effects when the pH of the medium was close to the drug pK. These effects were lowered when the transmembrane delta pH was dissipated, which indicates that the neutral form of the drug is implicated in the uncoupling mechanism. In addition, protonable derivatives of ellipticine display a linear relationship between oxidation rate and transmembrane potential, which suggests that the uncoupling properties of these molecules result from a protonophoric mechanism. From these results, the following cyclic protonophoric mechanism is proposed for protonable ellipticines: (i) electrophoretical accumulation of the protonated form; (ii) deprotonation at the matrix interface; (iii) diffusion outwards; and (iv) reprotonation at the external interface.

Consequences of omega -6-oleate desaturase deficiency on lipid dynamics and functional properties of mitochondrial membranes of Arabidopsis thaliana

We probed the role of the polyunsaturated fatty acids on the dynamic and functional properties of mitochondrial membranes using the fad2 mutant of Arabidopsis thaliana, deficient in omega-6-oleate desaturase. In mitochondria of this mutant, the oleic acid content exceeded 70% of the total fatty acids, and the lipid/protein ratio was greatly enhanced. As a consequence, local microviscosity, probed by anthroyloxy fatty acid derivatives, was increased by 30%, whereas the lipid lateral diffusion, assayed using 1-pyrenedodecanoic acid, was approximately 4 times increased. Functional parameters such as oxygen consumption rate under phosphorylating and nonphosphorylating conditions and proton permeability of the inner mitochondrial membrane were significantly reduced in fad2 mitochondrial membranes, while the thermal dependence of the respiration was enhanced. Moreover, metabolic control analysis of the respiration clearly showed an enhancement of the control exerted by the membrane proton leaks. Our data suggest that the loss of omega-6-oleate desaturase activity in Arabidopsis cells induced an enhancement of both microviscosity and lipid/protein ratio of mitochondrial membranes, which in turn were responsible for the change in lateral mobility of lipids and for bioenergetic parameter modifications.

Microspectrofluorometry of the protonation state of ellipticine, an antitumor alkaloid, in single cells

The protonation state and intracellular distribution of ellipticine were investigated in single human mammary T47D cells by confocal laser microspectrofluorimetry. In the cell nucleus, only the protonated form of ellipticine was detected as a direct consequence of its apparent pK increase upon DNA binding. Both protonated and neutral forms were present in the aqueous cytoplasm, where the pH is close to the drug pK. When cells were incubated in high concentrations of K+, a condition that depolarizes the plasma membrane potential, ellipticine cellular accumulation was reduced. In the cytoplasm, ellipticine was mainly bound to mitochondria, and its protonation equilibrium was shifted toward the neutral form. The fluorescence spectrum of ellipticine bound to mitochondria was insensitive to valinomycin, whereas it was markedly shifted toward the protonated form after carbonyl cyanide p-trifluoromethoxy-phenylhydrazone or nigericin addition. Similar studies with ellipticine bound to isolated mitochondria suggest that it behaves as a fluorescent probe of mitochondrial pH in both isolated mitochondria and single living cells.

Gal-lectin-dependent contact activates the inflammasome by invasive Entamoeba histolytica

Entamoeba histolytica (Eh) is an extracellular protozoan parasite of the human colon, which occasionally breaches the intestinal barrier. Eradicating ameba that invades is essential for host survival. A defining but uncharacterized feature of amebic invasion is direct contact between ameba and host cells. This event corresponds with a massive pro-inflammatory response. To date, pathogen recognition receptors (PRRs) that are activated by contact with viable Eh are unknown. Here we show that the innate immune system responds in a qualitatively different way to contact with viable Eh vs. soluble ligands produced by viable or dead ameba. This unique Eh Gal-lectin contact-dependent response in macrophages was mediated by activation of the inflammasome. Soluble native Gal-lectin did not induce inflammasome activation, but was sufficient for transcriptional priming of the inflammasome and non-inflammasome-dependent pro-inflammatory cytokine release. We conclude the inflammasome is a pathogenicity sensor for invasive Eh and identify for the first time a PRR that specifically responds to contact with intact parasites in a manner that accords with scale immune response to parasite invasion.

BiaCore analysis of leptin-leptin receptor interaction: evidence for 1:1 stoichiometry

Leptin is a hormonal protein involved in energy homeostatis that acts to inhibit food intake, to stimulate energy expenditure, and to influence insulin secretion, lipolysis, and sugar transport. Its action is mediated by a specific receptor whose activation is highly controversial. As a member of the cytokine receptor superfamily, it has been predicted to be activated by ligand-induced dimerization. However, recent evidence has indicated that this receptor exists as a dimer in both ligand-free and ligand-bound states. Here, the BiaCore has been used to measure the kinetics and stoichiometry of the interaction between the leptin and its receptor. Human or mouse receptor chimeras comprising two receptor extracellular domains fused to the Fc region of IgG(1) were captured on to the sensor via protein G. Kinetic data fitted to the simplest 1/1 model. The observed stoichiometry at ligand saturation was 1:1. Analyzing the binding mode and the reaction stoichiometry allowed us to conclude that the leptin receptor dimerization is not induced by ligand binding. This contradicts the common paradigm of cytokine receptor activation. Furthermore, data demonstrated a high-affinity interaction. The KD was 0.23+/-0.08 nM, with ka = (1.9 +/- 0.4) x 10(6) M(-1)s(-1) and kd = (4.4 +/- 0.6) x 10(-4) s(-1) for human leptin with its cognate receptor. Similar results were observed for the affinity of different species of leptin binding to mouse leptin receptor.

A comparison between bone reconstruction following the use of mesenchymal stem cells and total bone marrow in association with calcium phosphate scaffold in irradiated bone

The purpose of this study was to compare bone reconstruction using either mesenchymal stem cells (MSCs) or total bone marrow (TBM) in association with biphasic calcium phosphate (BCP) granules after irradiation in a rat model. Three weeks after an external irradiation of the hind limbs of rats, four bone defects were created per animal. The defects were filled with either BCP alone, or with a mixture of BCP and TBM, or with a mixture of BCP and MSCs (adipose-derived or bone marrow-derived MSCs). Three weeks after implantations, new-bone formation was assessed. Histological examination showed osteoconductive and osteointegrative properties of BCP in irradiated tissue. The BCP-TBM mixture significantly improved bone ingrowth (p<0.05). The BCP-MSCs mixtures did not provide new-bone formation over and above that induced by BCP alone. This gives grounds for suspecting that there is a link between this result and the cellular and vascular weakness observed in irradiated bone. The BCP-TBM mixture may have induced an increased vascularization of irradiated bone. This could be due to the presence of all components in TBM that were lacking in the BCP-MSCs mixtures. BCP associated with TBM appears to be the most efficient material for bone substitution in irradiated areas.

Role of beta 1- and beta 2-adrenoceptor subtypes in preconditioning against myocardial dysfunction after ischemia and reperfusion

Using an isolated nonworking rat heart model, this study investigated the role of beta-adrenergic preconditioning (beta-PC) to attenuate myocardial dysfunction after an ischemia/reperfusion injury. After a 20-min stabilization period, the noradrenaline depleted hearts were perfused for 5 min with isoproterenol (ISO) before 40-min global ischemia (I) followed by 30-min reperfusion (R). ISO 0.02 microM provided significant protection versus unconditioned in vivo reserpinized IR control, causing a decrease of creatine kinase (CK) release (mIU/min/g wet weight) on reperfusion in coronary effluent, a preservation of the mean coronary flow (MCF) and preservation of left ventricular function assessed by the rate-pressure product (RPP). These beneficial effects were similar to those of ischemic preconditioning (I-PC) in both nonreserpinized and reserpinized rats. Propranolol (1 microM) and atenolol (10 microM) completely suppressed the ISO preconditioning. In contrast, ICI 118551 (2 microM) a highly selective beta -blocker, did not blunt the salutary effects of ISO on CK release and MCF preservation. These results indicate that ISO pretreatment provides a significant cardioprotection against prolonged ischemic myocardial injury. Although endogenous catecholamines are not necessary for I-PC in isolated rat hearts, cardioprotection provided by beta-adrenergic stimulation is quite similar to I-PC. This significant cardioprotection is mediated less by beta -adrenoceptor than by beta -adrenoceptor activation, which seems to play a crucial role in the beta-PC mechanism.

Osteogenic properties of calcium phosphate ceramics and fibrin glue based composites

Calcium phosphate (Ca-P) ceramics are currently used in various types of orthopaedic and maxillofacial applications because of their osteoconductive properties. Fibrin glue is also used in surgery due to its haemostatic, chemotactic and mitogenic properties and also as scaffolds for cell culture and transplantation. In order to adapt to surgical sites, bioceramics are shaped in blocks or granules and preferably in porous forms. Combining these bioceramics with fibrin glue provides a mouldable and self-hardening composite biomaterial. The aim of this work is to study the osteogenic properties of this composite material using two different animal models. The formation of newly formed bone (osteoinduction) and bone healing capacity (osteconduction) have been study in the paravertebral muscles of sheep and in critical sized defects in the femoral condyle of rabbits, respectively. The different implantations sites were filled with composite material associating Ca-P granules and fibrin glue. Ca-P granules of 1-2 mm were composed with 60% of hydroxyapatite and 40% of beta tricalcium phosphate in weight. The fibrin glue was composed of fibrinogen, thrombin and other biological factors. After both intramuscular or intraosseous implantations for 24 weeks and 3, 6, 12 and 24 weeks, samples were analyzed using histology and histomorphometry and mechanical test. In all cases, the newly formed bone was observed in close contact and around the ceramic granules. Depending on method of quantification, 6.7% (with BSEM) or 17% (with micro CT) of bone had formed in the sheep muscles and around 40% in the critical sized bone rabbit defect after 24 weeks. The Ca-P/fibrin material could be used for filling bone cavities in various clinical indications.