<i>Trypanosoma rangeli:</i> growth in mammalian cells <i>in vitro</i> and action of a repositioned drug (17-AAG) and a natural extract (<i>Artemisia sp</i>. essential oil)

Trypanosoma rangeli and T. cruzi are both parasitic unicellular species that infect humans. Unlike T. cruzi, the causative agent of Chagas disease, T. rangeli is an infective and non-pathogenic parasite for humans, but pathogenic for vectors from the Rhodnius genus. Because both species can coexist in different hosts and overlap their infective cycles but very little is known about the infection of T. rangeli in mammalian cells, we decided to characterize both the development of this parasite in cell culture and the effect of therapeutic agents with potential trypanocidal action on it. We found that T. rangeli exhibits a cycle of infection in Vero cells similar to that for T. cruzi and that the repurposed drug, 17-AAG, and the natural extract Artemisia sp. essential oil produce a toxic effect on epimastigotes showing a trypanocidal action from the fifth day of culture. Both treatments also affected the infection of trypomastigotes and reduced the capacity of replication of amastigotes of T. rangeli. Since T. cruzi / T. rangeli coinfection cases have been reported, the finding of drugs with potential activity against both species could be significant in the future. Furthermore, studies of susceptibility of both species to drugs could also help to know the different mechanisms of pathogenicity in humans displayed by T. cruzi that are absent in T. rangeli     

Chemical Ecology of the host searching behavior in an Egg Parasitoid: are Common Chemical Cues exploited to locate hosts in Taxonomically Distant Plant Species?

Parasitoids are known to exploit volatile cues emitted by plants after herbivore attack to locate their hosts. Feeding and oviposition of a polyphagous herbivore can induce the emission of odor blends that differ among distant plant species, and parasitoids have evolved an incredible ability to discriminate them and locate their hosts relying on olfactive cues. We evaluated the host searching behavior of the egg parasitoid Cosmocomoidea annulicornis (Ogloblin) (Hymenoptera: Mymaridae) in response to odors emitted by two taxonomically distant host plants, citrus and Johnson grass, after infestation by the sharpshooter Tapajosa rubromarginata (Signoret) (Hemiptera: Cicadellidae), vector of Citrus Variegated Chlorosis. Olfactory response of female parasitoids toward plants with no herbivore damage and plants with feeding damage, oviposition damage, and parasitized eggs was tested in a Y-tube olfactometer. In addition, volatiles released by the two host plant species constitutively and under herbivore attack were characterized. Females of C. annulicornis were able to detect and significantly preferred plants with host eggs, irrespectively of plant species. However, wasps were unable to discriminate between plants with healthy eggs and those with eggs previously parasitized by conspecifics. Analysis of plant volatiles induced after sharpshooter attack showed only two common volatiles between the two plant species, indole and β-caryophyllene. Our results suggest that this parasitoid wasp uses common chemical cues released by many different plants after herbivory at long range and, once on the plant, other more specific chemical cues could trigger the final decision to oviposit.

     

Megavoltage imaging with low Z targets: implementation and characterization of an investigational system

The poor quality of stereotactic radiotherapy portal images is a limiting factor in precise image registration. To alleviate this problem, a low atomic number (Z) target was implemented on our Siemens MXE linear accelerator. This investigational system was used to assess the performance of various target materials by filming an aluminum contrast object. Beryllium, carbon and conventional target materials were studied. The bremsstrahlung spectra of these materials were simulated using Monte Carlo techniques. These spectra were used to calculate the dependence of narrow beam contrast on phantom thickness for verification of the data measured from film. A Monte Carlo simulation of the beryllium spectrum in a wide beam geometry was used to evaluate the effect of phantom-to-film distance on contrast. Although the same degree of contrast improvement with distance was not realized in practice, the improvement in image quality rivaled that achieved using a scatter reduction grid. A comparison of conventional localization images of the head and neck of an anthropomorphic phantom with images produced with a beryllium or carbon target and a mammography film and screen system supports earlier suggestions that the technique is clinically useful.     

Efficiency of wave impeding barrier in pipeline construction under earthquake excitation using nonlinear finite element analysis

Earthquakes have caused colossal casualties and severe damages to engineering structures and especially leading to substantial economic loss to the underground structures and/or infrastructures. Pipelines are one of most important component of lifeline engineering. For instance, the Southern Caucasus- Eastern Turkey energy corridors are formed by several key pipelines carrying crude oil and natural gas from Azerbaijan, via Georgia, to world markets through Mediterranean Sea. Many project accomplished recently and construction of new corridors are still going on. They should be protected from earthquake disaster especially when they pass through high seismicity zones. The installation of wave impeding barriers (WIB) below the vulnerable infrastructures as pipelines established in soft soil can be used to reduce the effect of the earthquake induced ground borne vibrations. In this paper, a WIB as artificial bedrock based on the cut-off frequency of a soil layer over bedrock is proposed as isolation measurement in order to mitigate the dynamic response of the buried pipelines under earthquake strong ground motion. The computational simulation of the wave propagation problem is directly achieved by employing nonlinear 2D finite element modelling for prediction of screening performance of WIB on the dynamic response of vibrating coupled soil-pipeline system. Energy absorbing boundaries along the truncated interfaces of the unbounded nature of the underlying soil media are implemented in the time domain along with Newmark’s integration. An extensive parametric investigation and systematic computations are performed with different controlling parameters. The obtained numerical results point out that WIB can be very promising as an isolator to protect pipelines when they establish for a certain depth.     

Effect of ketamine on heterogeneity of cerebral microregional venous O2 saturation in the rat

Heterogeneity of microregional O2 supply and consumption balance exists in the brain. Previous studies have shown that anesthetics such as pentobarbital and isoflurane, decrease the heterogeneity of O2 saturation in the small veins of the brain. This study was performed to determine whether ketamine, an anesthetic, would alter this heterogeneity. Rats were anesthetized with isoflurane for the cannulation of the femoral artery and vein. Ninety minutes after discontinuation of isoflurane, they either received injections with ketamine 100 mg/kg intraperitoneally (IP) (n = 7) or were used as conscious controls (n = 7). In each rat, regional cerebral blood flow (rCBF) was determined by 14C-iodoantipyrine autoradiography, and microregional arterial and venous (diameter 20-100 microns) O2 saturation was measured by microspectrophotometry in the anterior cortex, posterior cortex, and pons. The average rCBF and O2 consumption were similar between the two groups in each brain region except in the anterior cortex, where the O2 consumption of the ketamine group was slightly higher than that of the conscious animals. The average regional O2 supply-to-consumption ratios were similar in the three brain regions in both of the groups. However, there was heterogeneity of the O2 saturation in small veins in all the brain regions that we studied. The coefficient of variation [CV = (SD/mean X 100] of venous O2 saturation of the ketamine group in the anterior cortex (19.8 +/- 7.2), in the posterior cortex (18.8 +/- 9.4), and in the pons (16.7 +/- 6.5) was not significantly different from that in the conscious animals (22.8 +/- 6.4, 23.1 +/- 5.3, and 15.7 +/- 6.4, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Low anterior resection with a long posterior anorectal myectomy and sphincterectomy for Hirschsprung's disease

Nine patients with the severe form of Hirschhsprung's Disease (HD) underwent low anterior resection with posterior anal myectomy and sphincterectomy. Good results were achieved in six patients. Three patients had bouts of enterocolitis following the surgical treatment which was attributed to residual spasm of the aganglionic rectum and the internal anal sphincter. Myectomy had to be redone in two patients. One patient developed constipation which responded to toilet training. One patient died at home of an unknown cause, and one patient was lost to follow-up. The different methods of treatment of HD are discussed with emphasis on the role of the internal anal sphincter. The relatively high complication rate in this small group of patients does not justify its use in the severe form of HD.     

FLOW BEHAVIOUR AND STABILITY OF OIL-IN-WATER EMULSIONS STABILIZED BY A SUCROSE PALMITATE

The steady-state flow behaviour of oil-in-water emulsions stabilized by a sucrose palmitate was studied. Droplet size measurements were also carried out. The influence of sucrose ester (1–10% w/w) and oil concentrations (55–85% w/w) were analyzed. Influence of ageing was also studied. The Sisko and Carreau models were used to fit the experimental results depending on oil concentration. A master flow curve was obtained for all the oil and sucrose ester concentrations studied. The resulting master curve may be described fairly well by using a form of the Carreau model which includes a shift factor for both oil and sucrose ester concentration. The influence of the oil volume fraction on the shift factor was represented by a Frankel-Acrivos equation. A correlation between rheological properties and particle size parameters has also been established.