Molecular detection and identification of spotted fever group rickettsiae in ticks collected from horses in Cuba.

Spotted fever group (SFG) rickettsiae are obligatory intracellular bacteria that cause disease in humans and other animals. Ixodid ticks are the principal vectors of SFG rickettsiae. The present study aimed to determine the prevalence and species identity of SFG rickettsiae in ticks and horses from urban and rural areas of western Cuba using PCR assays. Tick samples, collected from 79 horses, consisted of 14 Amblyomma mixtum adults, 111 Dermacentor nitens adults and 19 pools of D. nitens nymphs (2-5 individuals/pool). The PCR results revealed the presence of Rickettsia spp. in 64% of the A. mixtum adults, 16% of the D. nitens adults, and 11% of the pooled samples of D. nitens nymphs. In contrast, Rickettsia spp. was not detected in any of the 200 horse blood samples included in this study. DNA sequence data of the rickettsial 17 kDa antigen gene showed that Rickettsia amblyommatis was present in A. mixtum; and Rickettsia felis in D. nitens. This is the first report of R. felis in D. nitens in Cuba. The present study extends our knowledge of the potential vector spectrum and distribution of SFG rickettsiae pathogens in western Cuba.

Endoscopist-directed propofol is more efficient than anesthesiologist-administered propofol in patients at low-intermediate anesthetic risk.

OBJECTIVE: Endoscopist-directed propofol (EDP) sedation is becoming more popular, with a reported safety and efficacy similar to anesthesiologist-administered propofol (AAP). The aim of this study is to compare the efficiency of EDP and AAP in patients of low-intermediate anesthetic risk. METHODS: A prospective cost-effectiveness comparison study was conducted. The costs of the endoscopic procedures in the EDP and AAP group were calculated using the full cost methodology after breaking down the endoscopic activity into relative value units to allocate costs in an equitable way. To determine the effectiveness, adverse events related to endoscopic sedation and the number of incomplete procedures were registered for the EDP group and compared with those published by anesthesiologists for AAP. RESULTS: A total of 1165 and 18 919 endoscopic procedures were, respectively, included in the EDP and AAP groups. The average costs of EDP vs. AAP for gastroscopy, colonoscopy and endoscopic ultrasound were &OV0556; 182.81 vs. &OV0556; 332.93, &OV0556; 297.07 vs. &OV0556; 459.76, and &OV0556; 319.92 vs. &OV0556; 485.12, respectively. No significant differences were detected regarding the rate of overall adverse events (4.43 vs. 4.46%) or serious adverse events (0 vs. 0.17%); the rate of arterial hypotension was significantly lower in the EDP group: 0.34 vs. 1.78% [odds ratio (OR), 0.19; 95% confidence interval (CI), 0.08-0.46] and the desaturation rate was significantly lower in the AAP group: 3.26 vs. 1.29% (OR, 2.58; 95% CI, 1.85-3.60). No significant differences were found in terms of incomplete examinations (0.17 vs. 0.14%). CONCLUSION: In patients with low-intermediate anesthetic risk referred for an endoscopic examination, EDP appears to be more efficient than AAP.

Inhibition of α-amylase by flavonoids: Structure activity relationship (SAR).

Flavonoids are recognized to regulate animals' food digestion processes trough interaction with digestive enzymes. The binding capacity of hesperetin (HES), luteolin (LUT), quercetin (QUE), catechin (CAT) and rutin (RUT) with pancreatic α-amylase were evaluated, using UV-Vis spectroscopy, fluorescence and molecular docking. Using p-nitrophenyl-α-d-maltopentoside (pNPG5) as substrate analog, LUT showed the best inhibitory capacity, even better than that of the positive control, acarbose (ACA). A mixed-type inhibition was observed for HES, LUT and QUE, a competitive-type for ACA, while no inhibition was observed with CAT and RUT. In agreement with kinetic results, α-amylase presented a higher affinity for LUT, when analyzed by fluorescence quenching. The binding of flavonoids to amylase followed a static mechanism, where the binding of one flavonoid per enzyme molecule was observed. Docking analysis showed that flavonoids bound near to enzyme active site, while ACA bound in another site behind the catalytic triad. Extrinsic fluorescence analysis, together with docking analysis pointed out that hydrophobic interactions regulated the flavonoid-α-amylase interactions. The present study provides evidence to understand the relationship of flavonoids structure with their inhibition mechanism.

Quantum conductance steps in solutions of multiwalled carbon nanotubes.

We have prepared solutions of multiwalled carbon nanotubes in Aroclor 1254, a mixture of polychlorinated biphenyls. The solutions are stable at room temperature. Transport measurements were performed using a scanning-tunneling probe on a sample prepared by spin coating the solution on gold substrates. Conductance steps were clearly seen. A histogram of a high number of traces shows maximum peaks at integer values of the conductance quantum G(0)=2e(2)/h, demonstrating ballistic transport at room temperature along the carbon nanotube over distances longer than 1.4 microm.

Stretched exponential relaxation for growing interfaces in quenched disordered media.

We study the relaxation for growing interfaces in quenched disordered media. We use a directed percolation depinning model introduced by Tang and Leschhorn for 1+1 dimensions. We define the two-time autocorrelation function of the interface height C(t('),t) and its Fourier transform. These functions depend on the difference of times t-t(') for long enough times, this is the steady-state regime. We find a two-step relaxation decay in this regime. The long time tail can be fitted by a stretched exponential relaxation function. The relaxation time tau(alpha) is proportional to the characteristic distance of the clusters of pinning cells in the direction parallel to the interface and it diverges as a power law. The two-step relaxation is lost at a given wavelength of the Fourier transform, which is proportional to the characteristic distance of the clusters of pinning cells in the direction perpendicular to the interface. The stretched exponential relaxation is caused by the existence of clusters of pinning cells and it is a direct consequence of the quenched noise.