Low intensity sonosynthesis of iron carbide@iron oxide core-shell nanoparticles

Here we demonstrate a simple method for the organic sonosynthesis of stable Iron Carbide@Iron Oxide core-shell nanoparticles (ICIONPs) stabilized by oleic acid surface modification. This robust synthesis route is based on the sonochemistry reaction of organometallic precursor like Fe(CO)₅ in octanol using low intensity ultrasonic bath. As obtained, nanoparticles diameter sizes were measured around 6.38 nm ± 1.34 with a hydrodynamic diameter around 25 nm and an estimated polydispersity of 0.27. Core-Shell structure of nanoparticles was confirmed using HR-TEM and XPS characterization tools in which a core made up of iron carbide (Fe₃C) and a shell of magnetite (γ-Fe₂O₃) was found. The overall nanoparticle presented ferromagnetic behavior at 4 K by SQUID. With these characteristics, the ICIONPs can be potentially used in various applications such as theranostic agent due to their properties obtained from the iron oxides and iron carbide phases.

[Dengue infection in children and adolescents in Panama]

BACKGROUND

Dengue is a serious emerging infectious disease and constitutes a major international health concern.

MATERIAL AND METHODS

All reports of confirmed dengue infection in patients aged less than 18 years old between 2000 and 2005 were included. A confirmed diagnosis was established by culture of the virus within the first 3 days of symptom onset or by serologic assays 5-30 days after symptom onset. Clinical and epidemiological features were analyzed.

RESULTS

A total of 457 patients were included (57.6 % female). The median age was 13 years (IQR 5 6). A greater number of cases were detected in urban areas and during the rainy season (May-November). Two epidemics were reported in 2001 (33.9 %) and the first eight months of 2005 (23.1 %). The most prevalent symptoms were fever (95.2 %), severe headache (74.2 %), chills (65.9 %), rash (63.5 %), myalgias (51.9 %) and retro-orbital pain (51.6 %). No significant differences were found between male and female patients. Significant differences in clinical features were found when the patients were divided into 3 groups; < 5 years old, 6-10 years old and > 10 years old. Fifty-three percent of the patients had had previous contact with a dengue-infected individual. There were 7 patients with dengue hemorrhagic fever, 4 of whom died.

CONCLUSIONS

Dengue virus infection is still a major health problem in Panama. To achieve effective control of dengue, further epidemiological studies, such as our own, are needed to design appropriate preventive measures.

Nonlocal impedances and the Casimir entropy at low temperatures

The problem with the temperature dependence of the Casimir force is investigated. Specifically, the entropy behavior in the low temperature limit, which caused debates in the literature, is analyzed. It is stressed that the behavior of the relaxation frequency in the T-->0 limit does not play a physical role since the anomalous skin effect dominates in this range. In contrast with the previous works, where the approximate Leontovich impedance was used for analysis of nonlocal effects, we give description of the problem in terms of exact nonlocal impedances. It is found that the Casimir entropy is going to zero at T-->0 only in the case when s polarization does not contribute to the classical part of the Casimir force. However, the entropy approaching zero from the negative side that, in our opinion, cannot be considered as thermodynamically satisfactory. The resolution of the negative entropy problem proposed in the literature is analyzed and it is shown that it cannot be considered as complete. The crisis with the thermal Casimir effect is stressed.

Feasibility and tolerability of transnasal/per-oral placement of the wireless pH capsule vs. traditional 24-h oesophageal pH monitoring--a randomized trial

BACKGROUND

The wireless pH is a new technique to monitor oesophageal acid exposure.

AIM

To compare the feasibility and tolerability of the wireless pH capsule vs. the traditional pH probe.

METHODS

Consecutive patients referred for a pH test were enrolled into the study. Patients were randomized to traditional pH probe, or wireless pH capsule. Patients recorded their activities, food consumption, symptoms, satisfaction with the test and completed a quality of life questionnaire.

RESULTS

Of the 50 patients recruited, 25 patients underwent placement of the traditional pH probe, and 25 the wireless pH capsule. Patients with the wireless pH capsule had less nose pain, runny nose, throat pain, throat discomfort and headache as compared with those with the traditional pH probe (P = 0.047, P = 0.001, P = 0.032, P = 0.001, P = 0.009, respectively). Patients in the wireless pH capsule group had more chest discomfort during the pH test (P = 0.037). Patients in the wireless pH capsule group perceived the test as interfering less with their overall daily activities, eating and sleep (P =0.001, P = 0.003, P = 0.025, respectively), and had overall satisfaction with the test (P = 0.023).

CONCLUSIONS

Transnasal/per-oral placement of the wireless pH capsule is significantly better tolerated then the traditional pH probe.

Intranasal Cry1Ac protoxin is an effective mucosal and systemic carrier and adjuvant of Streptococcus pneumoniae polysaccharides in mice

Streptococcus pneumoniae is a major respiratory pathogen in infants, children and the elderly. Available parenteral anti-pneumococcal vaccines based on type-specific capsular polysaccharides (CPSs) are useful in adults but do not elicit protective immunity in infants and young children. To enhance their immunogenicity, pneumococcal CPSs conjugated to proteins are being developed. Mucosal vaccines may induce mucosal and systemic immune responses, but their development has been hampered by the lack of effective, inexpensive innocuous mucosal adjuvants or immunogenic vaccine carriers. We have demonstrated that the recombinant Cry1Ac protoxin from Bacillus thuringiensis is highly immunogenic and has mucosal and systemic adjuvant effects on proteins coadministered in mice. In this work, we evaluated Cry1Ac as a carrier and adjuvant of S. pneumoniae CPS for the induction of mucosal and systemic antibody responses after intranasal and intraperitoneal immunization in mice. Our results demonstrate that intranasal application of pneumococcal polysaccharides either coadministered or conjugated with Cry1Ac induces higher systemic and mucosal specific antibody responses than those elicited by pneumococcal polysaccharides alone. Adjuvant effects of Cry1Ac on polysaccharides may be appropriate for vaccine design.

Serum growth hormone and ultrastructural studies of adenohypophysial tissue in bromocriptine treated acromegalic patients

The therapeutic effectiveness of bromocriptine as well as the post-operative ultrastructural aspects of treated pituitary adenomas were investigated in five acromegalic patients. Although concentrations of GH basal decreased and the glucose tolerance test and the TSH responses were significantly improved, the release of GH induced by TRH was not prevented by the dopaminergic agonist. Adenomatous cells were densely granulated and contained a dilated endoplasmic reticulum. Misplaced exocytosis was frequently observed. These findings clearly indicate that bromocriptine inhibits the spontaneous release of GH but does not interfere with the abnormal GH response to TRH. This suggests a separate site of action. The drug seems not to block the synthesizing activity of the adenomatous cell, a finding in accordance with clinical observations that warns against its use as a single therapeutic agent.