Stability of di-butyl-dichalcogenide-capped gold nanoparticles: experimental data and theoretical insights

Metals capped with organochalcogenides have attracted considerable interest due to their practical applications, which include catalysis, sensing, and biosensing, due to their optical, magnetic, electrochemical, adhesive, lubrication, and antibacterial properties. There are numerous reports of metals capped with organothiol molecules; however, there are few studies on metals capped with organoselenium or organotellurium. Thus, there is a gap to be filled regarding the properties of organochalcogenide systems which can be improved by replacing sulfur with selenium or tellurium. In the last decade, there has been significant development in the synthesis of selenium and tellurium compounds; however, it is difficult to find commercial applications of these compounds because there are few studies showing the feasibility of their synthesis and their advantages compared to organothiol compounds. Stability against oxidation by molecular oxygen under ambient conditions is one of the properties which can be improved by choosing the correct organochalcogenide; this can confer important advantages for many more suitable applications. This paper reports the successful synthesis and characterization of gold nanoparticles functionalized with organochalcogenide molecules (dibutyl-disulfide, dibutyl-diselenide and dibutyl-ditelluride) and evaluates the oxidation stability of the organochalcogenides. Spherical gold nanoparticles with diameters of 24 nm were capped with organochalcogenides and were investigated using X-ray photoelectron spectroscopy (XPS) to show the improved stability of organoselenium compared with organothiol and organotellurium. The results suggest that the organoselenium is a promising candidate to replace organothiol because of its enhanced stability towards oxidation by molecular oxygen under ambient conditions and its slow oxidation rate. The observed difference in the oxidation processes, as discussed, is also in agreement with theoretical calculations.

This study presents the improved stability against oxidation by molecular oxygen under ambient conditions of organoselenium compared with organothiol, and organotellurium.     

Mortality Risk Factors and Validation of Severity Scoring Systems in Critically Ill Patients with Acute Renal Failure

Background. Risk stratification and prediction of outcome in acute renal failure patients in the intensive care unit are important determinants for improvement of patient care and design of clinical trials. Methods. In order to identify mortality risks factors and validate general and specific predictive models for acute renal failure (ARF) patients in the intensive care unit (ICU), 324 patients were prospectively evaluated. Multivariate analysis by logistic regression was utilized for identification of mortality risk factors. Discrimination and calibration were used to evaluate the performance of the following models at referral to nephrologist and at initiation of renal replacement therapy: APACHE II, SAPS II, LODS, and ATN-ISI. Organ failure was assessed by SOFA and OSF. Results. The hospital mortality rate was 85%. The identified mortality risk factors were: age ≥ 65 yr, BUN ≥ 70 mg/dL, ARF of septic origin, and previous hypertension. Serum creatinine ≥ 3.5 mg/dL, systolic blood pressure ≥ 100 mm Hg, and normal consciousness were associated with mortality risk reduction. Performance of all prognostic models was disappointing with unsatisfactory calibration and underestimation of mortality on the day of referral to the nephrologist and at initiation of renal replacement therapy. Conclusions. Cross-validation of prognostic models for ARF resulted in poor performance of all studied scores. Therefore, a specific model is still warranted for the design of clinical trials, comparison of studies, and for prediction of outcome in ARF patients, especially in the ICU.     

Health and wellbeing of Victorian adults with intellectual disability compared to the general Victorian population

Multiple measures of health and wellbeing of people with intellectual disability (ID) and the general Victorian population were compared using representative population level data. The sample consisted of adults with ID (N = 897) and the general Victorian population (N = 34,168) living in the state of Victoria in Australia. Proxy respondents were interviewed on behalf of people with ID, while respondents from the general Victorian population were interviewed directly. The data were weighted to reflect the age/sex/geographic distribution of the population. Results revealed that adults with ID reported higher prevalence of poor social determinants of health, behavioural risk factors, depression, diabetes, poor or fair health. A higher proportion of people with ID reported blood pressure and blood glucose checks, while a lower proportion reported cervical and breast cancer screening, compared with the general Victorian population. The survey identified areas where targeted approaches may be undertaken to improve the health outcomes of people with ID and provide an important understanding of the health and wellbeing of these Victorians.     

Recent strategies for the development of oral medicines for the treatment of visceral leishmaniasis

Considered prevalent in many countries on five continents, especially in low-income regions, leishmaniasis is a neglected tropical disease classified by World Health Organization as one of the diseases for which the development of new treatments is a priority. It is an infectious disease caused by protozoa of the genus Leishmania, whose species may cause different clinical manifestations, such as cutaneous and visceral leishmaniasis (VL). Treatment is exclusively by drug therapy, as it has not been possible to develop vaccines yet. Currently available drugs are not fully effective in all cases; they have parenteral administration and exhibit a number of serious and very common adverse effects. The only oral drug available is expensive and it is not available in many endemic countries. Injectable administration is the main problem of treatments, since it requires patients to go to health centers, hospitalization and professional administration, which are conditions that are not adapted to the reality of the poverty conditions of patients with the disease. In this context, the development of an oral medicine has become a focus as it may solve many of these issues. Based on this scenario, this review aimed to investigate which therapeutic alternatives have been studied for the development of oral drugs directed to the treatment of human VL.     

Hydroelectrolytic balance of Brazilian jiu-jitsu athletes during a simulated competition

Purpose

To analyze the hydroelectrolytic balance of Brazilian jiu-jitsu athletes during a simulated competition.

Methods

Eight athletes were analyzed in simulated competition (four matches of 10 min). Blood lactate and rating of perceived exertion (6–20 scale) were used to infer the intensity of the matches. Blood samples were taken to determine the serum levels of osmolality, total protein and some electrolytes (chlorides, sodium, potassium, calcium, magnesium, phosphorus and iron).

Results

The lactate concentration changed during the simulated competition (F _7.49 = 35.5; P < 0.001; η ² = 0.85), with an increase post-match compared to the pre-match in matches 1, 2 and 4, but not for match 3. For rating of perceived exertion, no changes were found during the competition (F _3.21 = 9.4; P = 0.440; η ² = 0.12). The matches did not change the osmolality, chlorides, sodium, potassium, magnesium and iron values. For total protein, a difference was observed between the time-points (F _{2.8; 19.6} = 4.6; P = 0.015; η ² = 0.40), with lower concentrations in pre-match 2 than pre-match 1, post-matches 2 and 3. The calcium concentration was also affected by the simulated competition (F _7.49 = 4.0; P = 0.002; η ² = 0.37), with values lower in pre-match 2 than post-matches 1 and 2. The phosphorus serum was changed by matches (F _{3.1; 21.7} = 18.6; P < 0.001; η ² = 0.73), with post-match 1 values higher than the pre-matches 1, 2, 3 and 4 and post-match 3. The pre-match 4 values were lower than post-matches 2 and 4.

Conclusion

Although there were some changes during simulated competition, important alterations in the hydroelectrolytic balance did not occur.

     

Partial urethral obstruction of rabbit urinary bladder: stereological evidence that the increase in muscle content is mostly driven by changes in number, rather than size, of smooth muscle cells

The effects of partial urethral obstruction on the detrusor muscle of rabbit urinary bladder were investigated using stereological sampling and estimation tools. Twelve female Norfolk rabbits (2.5-3.0 kg body weight) were divided into four groups: 3, 7 and 12 weeks after surgical intervention to produce a standard partial obstruction and unobstructed controls. Following removal, bladder axes (craniocaudal, dorsoventral and laterolateral) and organ weights were recorded. Bladders were prepared for light microscopy by multistage random sampling procedures. Stereological methods were used to estimate the volume of muscle and the packing density and total number of myocyte nuclei in each bladder. We also estimated mean myocyte volume and the mean cross-sectional area and length of myocytes. Group comparisons were made by one-way analysis of variance. Changes in bladder axes were mainly laterolateral and craniocaudal. Mean bladder weight increased roughly six-fold by 3 weeks and 17-fold by 12 weeks and was accompanied, on average, by 12- and 33-fold increases in total muscle volume. These variables did not differ at 3 and 7 weeks post-obstruction. Increases in muscle content were not accompanied by changes in packing densities but were associated with increases in the total numbers of myocyte nuclei (13-fold by 3 weeks, 28-fold by 12 weeks). Mean myocyte volume did not vary significantly between groups but cells in obstructed groups were shorter and wider. These findings support the notion that partial outflow obstruction leads to an increase in the number, but not mean volume, of myocytes. If due solely to myocyte mitosis, the total of 43 x 10(8) cells found at 12 weeks could be generated by the original complement of 15 x 10(7) cells if an average of only 2.1 x 10(6) new cells was produced every hour. In reality, even this modest proliferation rate is unlikely to be achieved because myocyte proliferation rates are very low and it is possible that new myocytes can arise by differentiation of mesenchymal or other precursor cells.     

A population-based analysis of life satisfaction and social support among children of diverse backgrounds in British Columbia,Canada

Purpose

The Satisfaction With Life Scale adapted for Children (SWLS-C) is a self-report measure of children’s quality of life and has exhibited sound psychometric properties. In light of increasing ethno-cultural diversity, it is important to understand child life satisfaction across diverse subgroups. Employing children’s language background as a proxy for cultural background among children in British Columbia, Canada, we examined (a) the cross-cultural measurement equivalence of the SWLS-C; and (b) cross-cultural relations of peer support and adult support with SWLS-C.

Methods

Participants were 20,119 children (M_age 9.2; 50.2% boys) who provided data as part of a self-report child health survey (the Middle-years Development Instrument). Measurement equivalence across eight language/cultural background groups was tested via multi-group confirmatory factor analysis. Multi-level analyses were used to compare: a) SWLS-C means; and b) associations of peer support and adult support with SWLS-C scores, by language/cultural background.

Results

Findings supported strict measurement equivalence between the English language/cultural background group and all other language/cultural background groups for the SWLS-C. Relative to the English language background group, SWLS-C means differed for several language/cultural background groups. Within every language/cultural background group, however, peer and adult support scale scores were significant positive correlates of SWLS-C scores.

Conclusions

This study provided evidence for measurement equivalence of a life satisfaction measure across children from diverse language/cultural backgrounds and identified between-group differences in the level of child life satisfaction that were generally consistent with prior theory and findings. Moreover, results provided evidence of promotive associations of adult support and peer support with life satisfaction among diverse groups of children.