Effects of hyaluronan on free-radical formation, corneal endothelium damage, and inflammation parameters after phacoemulsification in rabbits.

Free-radical formation may play a role in postoperative complications of phacoemulsification (e.g., corneal endothelium damage from mechanical injury). The present experiments were aimed at investigating whether different molecular weight ranges (2000-2600, 2600-3200, or 3200-3800 kDa) of hyaluronan may influence free radical formation, corneal endothelium damage, and inflammation parameters after phacoemulsification in the rabbit eye. The viscoelastic substance was injected in the anterior chamber of rabbits' eyes before phacoemulsification, at a 2.5% concentration. The formation of free radicals was determined by adding luminol to the irrigation media and measuring the chemoluminescence in eyes. The corneal endothelial damage was evaluated by measuring the corneal central thickness by pachimetry. The inflammation parameters were measured by calculation in aqueous humor of peak levels of leukocytes and prostaglandin E(2) (PGE(2)) and evaluation in uveal tissue of myeloperoxidase activity. Hyaluronan decreased by about 58-60% free-radical formation during phacoemulsification, reduced by about 76-80% modifications in mean corneal thickness and by about 54-61% the corneal endothelial cell loss in all molecular weight ranges used. No difference was found among various molecular weight ranges. The highest molecular weight range showed to be more potent than the lowest range for reduced number of inflammation cells and level of PGE(2) in aqueous humor. Thus, hyaluronan reduces free-radical formation, exerts protection on the corneal endothelium and exerts anti-inflammation properties after phacoemulsification in rabbits. The latter effect seems to depend on the molecular weight of the substance.     

Antiadhesive and antibiofilm activity of hyaluronic acid against bacteria responsible for respiratory tract infections

To address the problem of limited efficacy of existing antibiotics in the treatment of bacterial biofilm, it is necessary to find alternative remedies. One candidate could be hyaluronic acid; this study therefore aimed to evaluate the in vitro antiadhesive and antibiofilm activity of hyaluronic acid toward bacterial species commonly isolated from respiratory infections. Interference exerted on bacterial adhesion was evaluated by using Hep‐2 cells, while the antibiofilm activity was assessed by means of spectrophotometry after incubation of biofilm with hyaluronic acid and staining with crystal violet. Our data suggest that hyaluronic acid is able to interfere with bacterial adhesion to a cellular substrate in a concentration‐dependent manner, being notably active when assessed as pure substance. Moreover, we found that Staphylococcus aureus biofilm was more sensitive to the action of hyaluronic acid than biofilm produced by Haemophilus influenzae and Moraxella catarrhalis. In conclusion, hyaluronic acid is characterized by notable antiadhesive properties, while it shows a moderate activity against bacterial biofilm. As bacterial adhesion to oral cells is the first step for colonization, these results further sustain the role of hyaluronic acid in prevention of respiratory infections.     

New Definition Criteria of Myocardial Dysfunction in Patients with Liver Cirrhosis: A Speckle Tracking and Tissue Doppler Imaging Study

There are no clear recommendations regarding cirrhotic cardiomyopathy (CC) evaluation in patients with pre-transplant liver cirrhosis. The roles of new methods, tissue Doppler imaging (TDI) and speckle tracking echocardiography (STE) in the diagnosis and prognosis of cirrhotic cardiomyopathy remain controversial. We investigated the utility of TDI/STE parameters in cirrhotic cardiomyopathy diagnosis and also in predicting mortality in patients with liver cirrhosis. Left/right ventricular function was studied using conventional TDI (velocities) and STE (strain/strain rate). We assessed left ventricular diastolic dysfunction, graded into four new classes (I/Ia/II/III). Serum NTproBNP (N-terminal prohormone of brain natriuretic peptide), troponin I, β-crosslaps, QTc interval, arterial compliance and endothelial function were measured. Liver-specific scores (Child–Pugh, MELD, MELDNa) were computed. There was a 1-y follow-up visit to determine mortality. We observed resting biventricular diastolic myocardial dysfunction, not presently included in the definition of cirrhotic cardiomyopathy. We provided an improved characterization of cardiac dysfunction in patients with liver cirrhosis. This might change the current definition. However, the utility of STE/TDI parameters in predicting long-term mortality in patients with liver cirrhosis remains controversial.     

Improving the role of echocardiography in studying the right ventricle of repaired tetralogy of Fallot patients: comparison with cardiac magnetic resonance

Right ventricular (RV) evaluation represents one of the major clinical tasks in the follow-up of repaired tetralogy of Fallot patients (rToF) with pulmonary valve regurgitation, as both severe RV dilatation and dysfunction are key factors in defining the need of pulmonary valve replacement. The aim of our study was to report the diagnostic accuracy of echocardiography in the identification of rToF patients with severely dilated and/or depressed RV as compared to cardiac magnetic resonance (CMR). Among our patients with rToF, a subgroup of 95 (17.6?±?6.8 years; 60% male), who underwent right ventricular qualitative and quantitative evaluation with CMR following echocardiographic suspicion of severe dilation/dysfunction, were included in the analysis. When comparing echocardiographic RV functional parameters to CMR findings, we found no association between CMR-ejection fraction (EF) and either tricuspid annulus plane systolic excursion (TAPSe) nor tissue Doppler systolic tricuspid excursion velocity (all p?=?ns). In contrast RVFAC was strongly associated with CMR-EF (r?=?0.44; p?<?0.01) as well as to longitudinal components of RV mechanics including tissue Doppler s′ (r?=?0.40; p?<?0.01) and TAPSE (r?=?0.36; p?<?0.01). When comparing echocardiographic and CMR structural parameters of the RV, we found that CMR RV volume was strongly related to echocardiographic measurements of RV end diastolic area (from the 4 chamber apical view) and with proximal parasternal short axis right ventricle outflow-dimension. Accordingly a regression model was derived from multiple regression analysis, which allows a more accurate estimate of CMR RV volume from echocardiography (r²?=?0.59, p?<?0.001). Our study demonstrates a significant, although imperfect, correlation between echocardiographic and CMR RV functional and geometrical parameters. Combining echocardiographic measures of RV inflow and RV outflow, we deliver a simple formula to estimate CMR-RV volume, improving the echocardiographic accuracy in RV volume quantification.     

Early identification of patients at risk for sinus node dysfunction after Mustard operation.

We studied 60 patients who had survived the Mustard procedure for transposition of the great arteries, performed between the ages of 2 days and 24 months (mean 4.51 +/- 3.79). All patients were given a postoperative 24-hour dynamic electrocardiogram at 15 days, 1 year and 3 years and then every 2 years. Those who were found to have sinus node dysfunction during follow-up, were given a dynamic electrocardiogram every 3-6 months. The average follow-up period was 38.7 +/- 19.8 months, median 36. Sinus node dysfunction was detected during follow-up in 20 patients (33.3% of the total), 8 of whom had had a pacemaker inserted. Risk factors for late development of sinus node dysfunction were found to include prolonged cross-clamping of the aorta during surgery (P = 0.003), especially over 50 minutes (relative risk 3.5:1), and the presence of even transient sinus node dysfunction after surgery (P = 0.006). These observations suggest, first, that sinus node dysfunction may develop after the Mustard operation as a combined effect of extensive atrial surgery and a long period of myocardial ischemia and, second, that the presence of the disease immediately after the operation sometimes indicates that it will recur or persist during follow-up.     

Small doses of melatonin increase intestinal motility in rats

Since melatonin receptors are present in the intestines, the possibility that this hormone may affect intestinal motility has been studied in the rat. Sprague-Dawley male rats were given a carmine cochineal powder meal and were injected intraperitoneally with 1, 10, 100, or 1000 g/kg melatonin. Sixty minutes after treatment, intestinal transit was found to be faster in animals treated with small doses of melatonin (1 or 10 g/kg) than in saline-injected controls. This effect, however, appear to be clearly reversed with 100 or 1000 g/kg melatonin. In fact, these doses of the hormone reduced intestinal transit in rats. The nonselective melatonin receptor antagonist, luzindole (administered intraperitoneally in a dose of 0.25 mg/kg, 15 min prior to melatonin injection) totally prevented the accelerating effect of melatonin (10 g/kg) on intestinal transit. Luzindole per se failed to affect gut motility. Injection of the reversible acetylcholinesterase inhibitor and cholinergic agent, neostigmine, accelerated intestinal transit but failed to influence melatonin effect on this parameter. In contrast, intraperitoneal injection of the muscarinic receptor antagonist atropine delayed intestinal transit per se but did not reduce the stimulating effect of melatonin on this parameter. Intestinal myoelectrical recording revealed that intestinal myoelectrical activity was increased by intraperitoneal injection of melatonin (10 g/kg). Administration of luzindole totally prevented melatonin-induced increase of intestinal myoelectrical activity. These results indicate that melatonin may affect intestinal motility in rats when administered in small doses. This effect might be mediated by melatonin receptors in the intestines, although the involvement of central receptors for the hormone is also possible.