An unusual foreign body in the rectum

This is the report of an unusual foreign body in the rectum which was a complication of the migration of an esophageal Celestin's prosthesis.     

Engineering DNA-Grafted Quatsomes as Stable Nucleic Acid-Responsive Fluorescent Nanovesicles

The development of artificial vesicles into responsive architectures capable of sensing the biological environment and simultaneously signaling the presence of a specific target molecule is a key challenge in a range of biomedical applications from drug delivery to diagnostic tools. Herein, the rational design of biomimetic DNA-grafted quatsome (QS) nanovesicles capable of translating the binding of a target molecule to amphiphilic DNA probes into an optical output is presented. QSs are synthetic lipid-based nanovesicles able to confine multiple organic dyes at the nanoscale, resulting in ultra-bright soft materials with attractiveness for sensing applications. Dye-loaded QS nanovesicles of different composition and surface charge are grafted with fluorescent amphiphilic nucleic acid-based probes to produce programmable FRET-active nanovesicles that operate as highly sensitive signal transducers. The photophysical properties of the DNA-grafted nanovesicles are characterized and the highly selective, ratiometric detection of clinically relevant microRNAs with sensitivity in the low nanomolar range are demonstrated. The potential applications of responsive QS nanovesicles for biosensing applications but also as functional nanodevices for targeted biomedical applications is envisaged.     

Behavior of explosive compacted/consolidated of nanometric copper powders

Nanosized particles of copper have been explosive compacted/consolidated with different process conditions using a cylindrical configuration as lay out, in order to preserve nanocrystallinity in 3D parts. After processing the specimens were characterized regarding the density, microstructure, grain size, and hardness using Archimedes method, SEM, XRD and depth-sensing indentation, respectively. The results show a significant bulk densification after explosion, associated to a nanocrystalline character, similar to the starting powders. For the sharpest parameters selected for the explosion a bimodal distribution of grain size is visible by SEM comparable to 2D nanocrystalline copper deposited by sputtering. The properties of “sintered parts” are compared with those of a standard resulting from densification of micropowders using the same technology, and the results highlight the future role of explosive densification of ductile nanopowder metals, as a suitable technique for macro- and micromanufacturing of nanostructured parts.     

Leptospirosis. Review of 11 cases]

Eleven cases of leptospirosis diagnosed from 1988 to 1994 were retrospectively reviewed. The mean age of the patients was 52 years. Epidemiologic factors were found in 10 patients. Hepatorenal involvement was observed in 7 cases (64%), cardiac involvement in 3 (27%), bleeding episodes in 5 (45%) and central nervous system involvement in one case (9%). The Leptospira serogroups identified were: Icterohaemorrhage in 6 cases, Pomona in 1, Sejroe in and could not be determined in 3. One patient died because of multiorgan failure. The epidemiologic, clinical, analytical and therapeutic aspects are discussed.     

Fast atrazine photodegradation in water by pulsed light technology

Pulsed light technology consists of a successive repetition of short duration (325 μs) and high power flashes emitted by xenon lamps. These flashlamps radiate a broadband emission light (approx. 200-1000 nm) with a considerable amount of light in the short-wave UV spectrum. In the present work, this technology was tested as a new tool for the degradation of the herbicide atrazine in water. To evaluate the presence and evolution with time of this herbicide, as well as the formation of derivatives, liquid chromatography-mass spectrometry (electrospray ionization) ion trap operating in positive mode was used. The degradation process followed first-order kinetics.Fluences about1.8-2.3 J/cm² induced 50% reduction of atrazine concentration independently of its initial concentration in the range 1-1000 μg/L. Remaining concentrations of atrazine, below the current legal limit for pesticides, were achieved in a short period of time. While atrazine was degraded, no chlorinated photoproducts were formed and ten dehalogenated derivatives were detected. The molecular structures for some of these derivatives could be suggested, being hydroxyatrazine the main photoproduct identified. The different formation profiles of photoproducts suggested that the degradation pathway may include several successive and competitive steps, with subsequent degradation processes taking part from the already formed degradation products. According to the degradation efficiency, the short treatment time and the lack of chloroderivatives, this new technology could be considered as an alternative for water treatment.     

Quantitation of intratumoral thymidylate synthase expression predicts for disseminated colorectal cancer response and resistance to protracted-infusion fluorouracil and weekly leucovorin

PURPOSE: Response rates to fluorouracil (5-FU)-based therapy remain low. As new, active agents are being tested, information regarding specific intratumoral genetic determinants of chemotherapy sensitivity or resistance can be used to plan therapy rationally. Intratumoral thymidylate synthase (TS) quantitation may be among the most important determinants of sensitivity or resistance to 5-FU. MATERIALS AND METHODS: Forty-six disseminated colorectal cancer patients had measurable tumor biopsies for polymerase chain reaction (PCR)-based determination of TS mRNA pretreatment. Protracted infusion of 5-FU 200 mg/m2/d for 21 days with weekly intravenous leucovorin 20 mg/m2 each cycle was given. After two cycles, responses were evaluated. Response data were correlated with independently determined intratumoral ratios of TS/beta-actin mRNA for each patient. RESULTS: TS/beta-actin ratios were successfully obtained for 42 patients (91%). TS/beta-actin ratios ranged from 0.3 x 10(-3) to 18.2 x 10(-3) (median, 3.5 x 10[-3]). Twelve patients (26%) responded to treatment (median TS/beta-actin ratio, 1.7 x 10[+3]). Thirty-four patients did not respond (median TS/beta-actin ratio, 5.6 x 10[-3]). No patient with a TS mRNA level greater than 4.1 x 10(-3) responded. The median TS/beta-actin ratio (3.5 x 10[-3]) significantly segregated responders from nonresponders (P = .001). Median survival for patients with TS/beta-actin ratios < or = 3.5 x 10(-3) was 13.6 months; for patients with TS/beta-actin ratios greater than 3.5 x 10(-3), it was 8.2 months (P = .02). CONCLUSION: For this cohort, the intratumoral TS/beta-actin ratio had a statistically significant association with response and survival. This relationship for other 5-FU schedules remains unknown. Confirmation of these data in a larger patient population could lead to determination of therapy for disseminated colorectal cancer based on a specific intratumoral molecular parameter.     

Effect of Yttria on the Thermal Conductivity of Aluminum Nitride

The effect of yttria additions up to 10 wt% on the thermal conductivity of pressureless-sintered aluminum nitride was investigated. Additions of up to 3 wt% increased the thermal conductivity to values around 160 W/(m·K). Additions higher than 5 wt% slowly decreased the thermal conductivity because of the increasing volume fraction of the low-conductivity yttrium aluminate phases. In all cases samples containing the same yttria content with the binder burned out in nitrogen had higher thermal conductivity than those with the binder burned out in air. Comparisons are made to previous studies containing additives of silica and calcia to aluminum nitride.     

Effect of CaO on the Thermal Conductivity of Aluminum Nitride

The effect of CaO on the thermal conductivity of aluminum nitride pressureless sintered with 3 wt% Y₂O₃ as a sintering aid was investigated. Over the composition range of 0 to 2.0 wt% additions, CaO decreased the thermal conductivity of the sintered parts by 10%. CaO doping rendered the secondary oxide phases more wetting and thus with a greater tendency to penetrate along the grain boundaries. Furthermore, CaO segregation to the grain boundaries was observed even on those grain boundaries apparently free of secondary phases. These microstructural changes disrupted the connectivity of the high thermal conductivity AIN grains and were the main factors contributing to the decrease in the thermal conductivity of the ceramic parts. CaO additions to samples doped with SiO₂ had the opposite effect, increasing the thermal conductivity. CaO removed SiO₂ from the AIN grains and incorporated it into the oxide second phases, most likely through charge-compensating substitutions Ca²⁺+ Si⁴⁺ for Y³⁺ and/or Al³⁺. Thus, AIN samples containing both SiO₂ and CaO had higher thermal conductivity than those containing comparable amounts of SiO₂ alone.     

Effect of Silica on the Thermal Conductivity of Aluminum Nitride

The effect of SiO₂ on the thermal conductivity of aluminum nitride pressureless sintered with 3 wt% Y₂O₃ as a sintering aid was investigated. SiO₂ additions greatly decreased the thermal conductivity of the sintered parts from values of around 160 W/m·K on undoped samples to about 25 W/m·K with 5 wt% SiO₂ added to the green body composition. Microstructural studies, combined with the temperature dependence of the thermal conductivity and lattice parameter measurements, indicated that defect phonon scattering was the mechanism responsible for the decrease in thermal conductivity. SiO₂ can be incorporated in limited solid solution into the AIN lattice, generating AI vacancies for charge compensation in a process not unlike the solution of oxygen in AIN. The mass difference introduced by the vacancies is the main phonon scattering defect. Beyond a concentration threshold of 2%, the SiO₂-induced defects cluster to form SiAION polytypoids derived from the basic 2H AIN structure with stacking sequences that depend on the SiO₂ levels in the sample.