The effect of fiber orientation on the thermal expansion coefficients of fiber-reinforced composites.

OBJECTIVES: The aim of this study was to characterize the thermal expansion and dimensional changes of fiber-reinforced composite (FRC) according to the fiber orientation, brand of FRC product and polymerization conditions. METHODS: Cubic specimens (n=5) were prepared from different brands of FRC and particulate filler composites and dimethacrylate monomer resin. The specimens were polymerized with a light-curing device for 40 s or additionally with prolonged polymerization in the light-curing oven for 15 min. Linear coefficients of thermal expansion (LCTE) values for different materials and for FRC with different fiber orientations were determined using a thermomechanical analyzer. RESULTS: All specimens exhibited linear increase in the value of LCTE between 37 and 67 degrees C. The analysis of ANOVA revealed that orientation of fiber and brand of material had significant effect (P<0.001) on LCTE values for 37-67 degrees C interval. Some interaction between factors also existed. Also, temperature interval 110-150 degrees C had significant effect on the LCTE values according to the curing unit, brand and orientation of fibers. SIGNIFICANCE: The results of this study suggest that the anisotropic nature of FRC exists also with regard to thermal expansion. The variation of LCTE of FRC compared to that of particulate filler composites might influence the interfacial adhesion of FRC appliances.     

Cyclosporine induces myocardial connective tissue growth factor in spontaneously hypertensive rats on high-sodium diet

BACKGROUND: The introduction of cyclosporine (CsA) has led to an improvement in the prognosis of solid organ transplantation. However, drug-induced hypertension and nephrotoxicity, associated with the development of atherosclerosis and coronary heart disease, still worsen the long-term outcome of CsA-treated patients. Whether the CsA-induced myocardial changes are associated with the induction of connective tissue growth factor (CTGF), a recently found polypeptide implicated in extracellular matrix synthesis, is not known. METHODS: Spontaneously hypertensive rats (8-9 weeks old) were treated with CsA (5 mg x kg(-1) x d(-1) subcutaneously) for 6 weeks. The influence of angiotensin-converting enzyme inhibition (enalapril 30 mg x kg(-1) x d(-1) orally) and angiotensin-1 receptor blockade (valsartan 3 and 30 mg x kg(-1) x d(-1) orally) on CsA toxicity was also investigated. Myocardial morphology was examined, and vascular lesions were scored. Localization and the quantitative expression of CTGF, as well as collagen I and collagen III, mRNA were evaluated by in situ hybridization and Northern blot. RESULTS: CsA-induced hypertension and nephrotoxicity were associated with myocardial infarcts and vasculopathy of the coronary arteries. CsA increased myocardial CTGF, collagen I, and collagen III mRNA expressions by 91%, 198%, and 151%, respectively. CTGF mRNA expression colocalized with the myocardial lesions. Blockade of the renin-angiotensin system prevented vascular damage and the CsA-induced CTGF, collagen I, and collagen III mRNA overexpressions in the heart. CONCLUSIONS: CsA increases CTGF, collagen I, and collagen III mRNA expressions in the heart. The induction of CTGF gene is mediated, at least in part, by angiotensin II.     

Combined inhibition of neutral endopeptidase with angiotensin converting enzyme or endothelin converting enzyme in experimental diabetes

OBJECTIVE: The effects of combined inhibition of neutral endopeptidase (NEP) with either angiotensin-converting enzyme (ACE), or endothelin-converting enzyme (ECE) on blood pressure, urinary albumin excretion and heart weight were explored in experimental diabetes. DESIGN : Streptozotocin-induced diabetic Sprague-Dawley rats were treated with vehicle, the NEP/ACE inhibitor S 21402, the NEP/ECE inhibitor CGS 26303, the NEP inhibitor SCH 42495, the ACE inhibitor captopril or the endothelin receptor antagonist bosentan for 4 weeks. METHODS: Blood pressure was measured by tail-cuff method and radiotelemetry. Albuminuria, plasma renin activity and plasma atrial natriuretic peptide (ANP) were determined by radioimmunoassay. NEP binding was assessed by in vitro quantitative autoradiography. Metabolic and biochemistry parameters including food intake, 24-h urine volume, plasma glucose, glycated hemoglobin, glomerular filtration rate (GFR) and urinary sodium excretion were also determined. RESULTS: Mean blood pressure over the 4-week study period after commencement of treatment was reduced to a similar extent by a range of treatments including the ACE inhibitor, NEP/ACE inhibitor, endothelin receptor antagonist, NEP/ECE inhibitor, but not the NEP inhibitor, compared with vehicle-treated diabetic rats. Heart to body weight ratio in diabetic rats was only reduced by the NEP/ACE and the NEP/ECE inhibitor. Increased albuminuria in diabetic rats (1.1 times/divided by 1.2 mg/day) was reduced by the NEP/ACE (0.6 times/divided by 1.2 mg/day) and the NEP/ECE inhibitors (0.4 times/divided by 1.2 mg/day). Renal NEP was reduced by the NEP/ACE inhibitor (35 +/- 4%) or NEP/ECE inhibitor (38 +/- 4%) as well as by the pure NEP inhibitor (27 +/- 4%) compared with the untreated diabetic group. Other abnormal metabolic and biochemical parameters in diabetic rats were not influenced by any drug treatment. CONCLUSIONS: Combined inhibition of NEP/ACE or NEP/ECE confers beneficial effects on blood pressure, albuminuria and heart to body weight ratio in experimental diabetes.     

Complications associated with central venous access device in children with haemophilia: a nationwide multicentre study in Finland

Children with haemophilia require venous access for regular infusion of coagulation factors. A central venous access device (CVAD) ensures long‐term access but associates with infectious and non‐infectious complications with proposed risk factors of young age at initial CVAD implantation and presence of an inhibitor. Our aim was to evaluate the incidence and risk factors for complications associated with CVAD usage in a retrospective nationwide multicentre study in five Finnish Paediatric Haemophilia Treatment Centers. Our study investigated 106 CVADs in 58 patients with 137 971 CVAD days. The median access survival was 1159 CVAD days, and most often a malfunction led to CVAD removal after a long survival (median of 1640 CVAD days). We detected a very low bloodstream infection rate (0.12/1000 CVAD days). The presence of neutralizing inhibitor was a significant risk factor for infection. Heparin vs. saline flushing did not influence the CVAD outcome. We detected a lower infection rate than previously reported, although 90% of the patients were very young (<2 years) at first insertion (median age = 1.02 year). Port access was frequent after initial implantation: six patients (10%) used the port daily for immune tolerance induction therapy and 74% at least twice weekly for prophylaxis. Young age did not increase the risk of infections, as 59% of the CVAD‐related infections were recorded in children over 6 years of age. Our national experience confirms the safety of prophylactic factor concentrate administration via ports even in very young children.     

Procoagulant activity on platelets adhered to collagen or plasma clot

In a new 2-stage assay of platelet procoagulant activity (PCA), we first subjected gel-filtered platelets to adhesion on collagen (as a model of primary hemostasis) or plasma clots (as a model of preformed thrombus) for 30 minutes, and then the adherent platelets were supplemented with pooled, reptilase-treated, diluted plasma. Defibrinated plasma provided coagulation factors for assembly on platelet membranes without uncontrolled binding of thrombin to fibrin(ogen). Platelet adhesion to both surfaces showed modest individual variation, which increased at platelet densities that allowed aggregation. However, adhesion-induced PCA varied individually and surface-independently >3-fold, suggesting a uniform platelet procoagulant mechanism. Permanently adhered platelets showed markedly enhanced PCA when compared with the platelet pool in suspension, even after strong activation. The rate of thrombin generation induced by clot-adherent platelets was markedly faster than on collagen-adherent platelets during the initial phase of coagulation, whereas collagen-induced PCA proceeded slowly, strongly promoted by tissue thromboplastin. Therefore at 10 minutes, after adjustment for adhered platelets, collagen supported soluble thrombin formation as much as 5 times that of the thrombin-retaining clots. Activation of platelets by their firm adhesion was accompanied by formation of microparticles, representing about one third of the total soluble PCA. Collagen-adhered platelets provide soluble thrombin and microparticles, whereas the preformed clot serves to localize and accelerate hemostasis at the injury site, with the contribution of retained thrombin and microparticles.     

Risk of thromboembolism in 14,000 individuals with coeliac disease

The risk of venous thromboembolism (VTE) was examined in individuals with coeliac disease (CD). The Swedish national inpatient register was used to identify 14 207 individuals with a diagnosis of CD (1964-2003). These individuals were matched for age, sex, calendar year and county with 69 048 reference individuals. Cox regression was used to estimate hazard ratios (HRs) for subsequent thromboembolism in individuals with more than 1 year of follow-up and no prior VTE. CD was associated with an increased risk of subsequent VTE (HR = 1.86; 95% confidence interval (CI) 1.54-2.24). The risk increase was restricted to individuals with CD diagnosed in adulthood. Risk estimates were not affected by the presence of diabetes mellitus or concomitant surgery. Compared with inpatients as reference individuals, CD individuals remained at increased risk of subsequent VTE (adjusted HR = 1.27; 95% CI = 1.06-1.52). In conclusion, this study found a statistically significantly positive association between CD and VTE. This modest association might be explained by a combination of surveillance bias and chronic inflammation.