Antibacterial effect of two glycine betaine analogues against Escherichia coli

Strains of enterobacteria that cause urinary tract infections are able to grow in urine with high tonicity. In such conditions bacterias adapt to osmotic forces by incorporation of osmoprotectant compounds including glycine betaine. Accumulation of toxic analogues in bacteria, using inducible betaine transporters, has been previously proposed for development of antibiotics. In this study we report antibacterial effect of two analogues against 82 strains of Escherichia coli isolated form urinary tract infections. Minimal inhibitory concentrations have been measured with and without osmotic stress. The betaine analogues have antibacterial effect against E. coli strains, but only in presence of an osmotic stress.     

Assessment of intraspecific mtDNA variability of European Ixodes ricinus sensu stricto (Acari: Ixodidae).

The Ixodes ricinus complex is composed of 14 species distributed worldwide. Some members of this complex are involved in the transmission of a number of diseases to animals and humans, in particular Lyme borreliosis, tick-borne encephalitis, ehrlichiosis and babesiosis. While the phylogenetic relationships between species of the I. ricinus complex have been investigated in the past, still little is known about the genetic structure within the species I. ricinus sensu stricto. We have investigated the intraspecific variability among 26 I. ricinus s.s. ticks collected in various European countries, including Switzerland, Italy, Austria, Denmark, Sweden, and Finland by using five mitochondrial gene fragments corresponding to the control region, 12S rDNA, cytb, COI, and COII. The five genes considered here showed a low genetic variability (1.6-5%). Our results based on both statistical parsimony (applied to the COI + COII + cytb + 12S + CR data set, for a total of 3423 bp) and maximum parsimony (applied to the COI + COII + cytb + 12S data set, for a total of 2980 bp) did not provide any evidence for a correlation between the identified haplotypes and their geographic origin. Thus, the European I. ricinus s.s. ticks do not seem to show any phylogeography structure.     

Chronic heart rate reduction by ivabradine prevents endothelial dysfunction in dyslipidaemic mice

BACKGROUND AND PURPOSE: High resting heart rate is a predictor for total and cardiovascular mortality independent of other risk factors in patients with coronary artery disease. We tested the hypothesis that a reduction of resting heart rate with the cardiac pacemaker I(f) current inhibitor ivabradine prevents the endothelial dysfunction associated with dyslipidaemia. EXPERIMENTAL APPROACH: Three-month-old dyslipidaemic (DL) male mice expressing the human ApoB-100 were assigned or not (DL, n=16), to treatment for 3 months with ivabradine (10 mg kg(-1) d(-1), n=17). Wild-type C57Bl/6 mice (WT, n=15) were used as controls. Heart rate was measured at 3, 4.5 and 6 months. Dilatation to acetylcholine (ACh) of isolated cerebral and renal arteries was investigated at 6 months. KEY RESULTS: Heart rate remained stable in anaesthetized WT mice, increased (25%, P<0.05) with age in DL mice but was limited (11%, P<0.05) by ivabradine. At 6 months, left ventricular maximal pressure was similar in all groups. The minimal and end-diastolic left ventricular pressures were increased (P<0.05) in DL (10.2+/-1.0 and 18.7+/-1.4 mm Hg) compared to WT (-0.4+/-0.7 and 6.3+/-1.0 mm Hg) and reduced (P<0.05) by ivabradine (4.2+/-1.3 and 11.5+/-1.5 mm Hg). ACh-induced maximal dilatation was impaired (P<0.05) in renal and cerebral arteries isolated from DL compared to WT (56+/-7 versus 83+/-3% in renal arteries; 22+/-2 versus 42+/-2% in cerebral arteries). Ivabradine completely prevented (P<0.05) this dysfunction in renal and cerebral arteries. CONCLUSIONS AND IMPLICATIONS: Selective heart rate reduction with ivabradine limits cardiac dysfunction and prevents the renovascular and cerebrovascular endothelial dysfunction associated with dyslipidaemia.     

Thermosensitive chitosan-based hydrogel containing liposomes for the delivery of hydrophilic molecules.

A novel injectable in situ gelling thermosensitive chitosan-beta-glycerophosphate (C-GP) formulation has been recently proposed for tissue repair and drug delivery. The system can sustain the release of macromolecules over a period of several hours to a few days. However, with low-molecular-weight hydrophilic compounds, the release is generally completed within 24 h. In this study, liposomes were added to the C-GP solution and their effect on the viscoelastic properties of the system and release kinetics of encapsulated carboxyfluorescein was investigated. The gelation rate and gel strength were slightly increased by the presence of the liposomes. The in vitro release profiles demonstrated controlled delivery over at least 2 weeks. The release rate strongly depended on the liposome size and composition (i.e. addition of cholesterol), and on the presence of phospholipase in the release medium. The kinetics was not substantially modified when using liposomes prepared with a negatively-charged lipid or a lipid having a high phase transition temperature. These results indicate that the liposome-C-GP system rapidly gels at body temperature, and can sustain the delivery of low-molecular-weight hydrophilic compounds. A mathematical model was proposed to characterize the release kinetics.     

Long-term follow-up of patients with endoscopic treatment of sporadic adenomas of the papilla of vater

BACKGROUND AND STUDY AIMS: Knowledge about the long-term outcome of patients after endoscopic treatment of ampullary adenomas remains poor, although surgical series have suggested that the initial endoscopic evaluation of these diseases might overlook cancer foci developed in adenomas. The aim of this study was to evaluate retrospectively the long-term outcome in patients with ampullary adenomas treated endoscopically, with a focus on the possible development of cancer. PATIENTS AND METHODS: The study included 24 patients (median age 59 years, range 34 - 84) with macroscopically benign adenomas of the papilla of Vater treated using mainly laser photodestruction between 1983 and 1996. Medical, endoscopic, surgical, and histological reports were reviewed. Patients and general practitioners were contacted to determine patient outcome when endoscopic follow-up had been discontinued. RESULTS: Endoscopic remission (macroscopic and histological) was achieved in 16 patients (66.6 %) with one recurrence (6.2 %) during a mean endoscopic follow-up of 66 months (4-168 months). Endoscopic treatment was discontinued in five (20.8 %) patients (with minimal residual adenoma and advanced age and/or severe unrelated disease), and failed in three patients (12.5 %) (failure of Nd:YAG laser in one case, severe pancreatitis and pancreatic duct ingrowth in one case each). After a mean clinical follow-up of 81 months (8-172 months), two patients (8.3 %) had undergone pancreaticoduodenectomy; eight (33.3 %) had died from unrelated diseases; and 14 (58.3 %) were alive and asymptomatic without any evidence of ampullary cancer. CONCLUSIONS: Long-term follow-up revealed no case of advanced ampullary cancer and suggested that endoscopic treatment was satisfactory for the large majority of patients with ampullary adenomas.     

Areca nut extracts reduce the intracellular reactive oxygen species and release of myeloperoxidase by human polymorphonuclear leukocytes

BACKGROUND AND OBJECTIVE: Polymorphonuclear leukocytes (PMN) represent the first line of host defense. Areca nut extract inhibits the bactericidal activity of, and the release of superoxide anion (O2- ) by, PMN. This study investigated the effects of areca nut extract on the intracellular production of reactive oxygen species (ROS) and on the extracellular release of lysosomal enzyme, myeloperoxidase (MPO), by PMN. The effects of arecoline, a principal component of areca nut, were also examined. MATERIAL AND METHODS: Human PMN were treated with various concentrations of areca nut extract or arecoline followed by treatment with Hanks' balanced salt solution, with or without cytochalasin B and fMet-Leu-Phe (CB/fMLP). The viability of PMN was determined using propidium iodide staining and flow cytometry. The presence of intracellular ROS was determined using 2',7'-dichlorofluorescin diacetate and fluorometry. MPO release was determined using a substrate assay. RESULTS: Areca nut extract (25 and 50 microg/ml) significantly decreased the viability of PMN. The intracellular levels of ROS and the extracellular release of MPO were induced in PMN by CB/fMLP. Exposure of PMN to areca nut extract (up to 25 microg/ml) or to arecoline (up to 2 mg/ml) did not directly affect the levels of ROS and MPO activity. However, under conditions that did not affect the viability of PMN, the ability of CB/fMLP to trigger production of intracellular ROS and release of MPO in human PMN was significantly suppressed by areca nut extract and arecoline. CONCLUSION: Areca nut impaired the activation of PMN by CB/fMLP that might decrease the effectiveness of PMN in the host defense. Alternatively, exposure of PMN to areca nut extract could decrease the capacity of PMN to damage tissues.     

Is flow cytometry really adapted to the determination of sperm concentration?

It has been reported that flow cytometry can be used as a reference procedure to determine sperm concentrations in quality control schemes in andrology laboratories, but there are no convincing quality control data. To understand comprehensively whether flow cytometry can be used to determine sperm concentration, sperm concentrations of 85 human semen samples were detected using three different methods, namely flow cytometry, computer-assisted semen analysis (CASA) and manual counting with a cell-VU chamber. The bead concentrations of both low [(18+/-2.5)x10(6)/mL] and high [(35+/-5)x10(6)/mL] pre-calibrated standard latex bead solutions were also determined with flow cytometry. The results showed that bead concentrations of both low and high pre-calibrated standard latex bead solutions counted five times with flow cytometry were (21.37+/-0.85)x10(6)/mL and (45.95+/-1.76)x10(6)/mL, respectively. Coefficient variances (CVs) and relative errors (REs) were 4%, 15.51% and 3.84%, 31.3% for low and high latex bead solutions, respectively. The overall correlation between values measured with flow cytometry and values measured with the cell-VU chamber and the CASA system was significant. However, flow cytometry overestimated the sperm concentration by 109% compared to the results with the cell-VU chamber. Moreover, for the azoospermic samples analysed, the sperm concentration was estimated at 0.12 (range from 0.04 to 0.24)x10(6)/mL. In conclusion, the data demonstrated that flow cytometry can result in an overestimation of both bead counting and sperm concentration, suggesting that flow cytometry is an inappropriate method for sperm counting, especially in the case of azoospermia.