Rita Santos

Novel semisynthetic derivatives of betulin and betulinic acid with cytotoxic activity

A series of new imidazole carboxylic esters (carbamates) and N-acylimidazole derivatives of betulin and betulinic acid (14-29) have been synthesized. The new compounds were screened for in vitro cytotoxicity activity against human cancer cell lines HepG2, Jurkat and HeLa. A number of compounds have shown IC(50) values lower than 2 microM against the cancer cell lines tested and the vast majority has shown a better cytotoxicity profile than betulinic acid, including the betulin derivatives. N-Acylimidazole derivatives 26 and 27 (IC(50) 0.8 and 1.7 microM in HepG2 cells) and the C-3 carbamate derivative 16 (IC(50) 2.0 microM in HepG2 cells) were the most promising compounds. Based on the observed cytotoxicity, structure-activity relationships have been established.

The link between local environment and obesity: A multilevel analysis in the Lisbon Metropolitan Area, Portugal

Although individual factors have been shown to predict weight gain, contextual determinants have also attracted attention, with some authors stressing the role played by deprivation, urban sprawl, social capital and safety. Recent evidence has implicated environmental factors that facilitate the consumption of excess calories and/or make it more difficult to expend them in routine physical activity. The interrelationships found in some places between physical and social environments (key mediators) and body mass index (BMI), as well as the potential that exists for the development of healthier places, mean that more research is required into the contextual determinants of health. In Portugal, particularly in the Lisbon Metropolitan Area (LMA), the effects of physical and social environments on physical activity and BMI have not previously been explored in any detail. This study aims to highlight the associations between residential (physical and social) environment and the risk of weight gain and obesity, over and above individual attributes, assessing which indicators are the best predictors of excess weight in the LMA. The study involved data from 7669 individuals aged 18 and over from 143 neighbourhoods. Self-reported body height and weight were used to define overweight body mass index (BMI> or =25). BMI and individual (socio-demographic and behavioural) characteristics were linked to contextual data and analysed in a multilevel framework. Our findings show that different environmental factors are significantly associated with excess weight and obesity, either directly or indirectly (e.g. health-related behaviours such as eating patterns and physical activity, which are key mediators), after adjustment for individual characteristics. The results suggest that a deeper understanding of these mechanisms is critical if we want to tackle the obesity epidemic, and that policies aimed at weight control and obesity reduction must address people and places in order to bear fruit.

Sodium hyaluronate/chitosan polyelectrolyte complex scaffolds for dental pulp regeneration: Synthesis and characterization

In the present study, small-sized porous scaffolds were obtained from the freeze-drying of sodium hyaluronate/chitosan polyelectrolyte complexes. The obtained materials were characterized by a set of techniques including attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, swelling determination and weight loss studies. The morphology of the scaffolds was observed using scanning electron microscopy. Thermal characterization of the scaffolds was also performed by dynamic mechanical thermal analysis and thermogravimetric analysis. Finally, the cytotoxic profile of the prepared scaffolds was evaluated in vitro, using mesenchymal stem cells. The results obtained showed that cells adhered to scaffolds and proliferated. This study also confirmed that the degradation by-products of sodium hyaluronate/chitosan scaffold are noncytotoxic, which is fundamental for its application in the biomedical field.

Synthesis and structure–activity relationship study of novel cytotoxic carbamate and N-acylheterocyclic bearing derivatives of betulin and betulinic acid

Chemical transformation studies were conducted on betulin and betulinic acid, common plant-derived lupane-type triterpenes. The concise synthesis, via a stepwise approach, of betulin and betulinic acid carbamate and N-acylheterocyclic containing derivatives is described. All new compounds, as well as betulinic acid were tested in vitro for their cytotoxic activity. Most of the compounds have shown a better cytotoxic profile than betulinic acid, including the synthesized betulin derivatives. Compounds 25 and 32 were the most promising derivatives, being up to 12-fold more potent than betulinic acid against human PC-3 cell lines (IC(50) values of 1.1 and 1.8 microM, respectively).

New betulinic acid derivatives induce potent and selective antiproliferative activity through cell cycle arrest at the S phase and caspase dependent apoptosis in human cancer cells.

New semisynthetic derivatives of betulinic acid (BA) RS01, RS02 and RS03 with 18-45 times improved cytotoxic activity against HepG2 cells, were tested for their ability to induce apoptosis and cell cycle arrest in HepG2, HeLa and Jurkat cells. All the compounds induced significant increase in the population at the S phase more effectively than BA. RS01, RS02 and RS03 were also found to be potent inducers of apoptosis with RS01 being markedly more potent than BA, suggesting that the introduction of the imidazolyl moiety is crucial for enhancing the induction of apoptosis and the cell cycle arrest. The mechanism of apoptosis induction has been studied in HepG2 cells and found to be mediated by activation of the postmitochondrial caspases-9 and -3 cascade and possibly by mitochondrial amplification loop involving caspase-8. These facts were corroborated by detection of mitochondrial cytochrome c release and DNA fragmentation. Because RS01, RS02 and RS03 exhibited significant improved antitumor activity with respect to BA, they may be promising new agents for the treatment of cancer. In particular, RS01 is the most promising compound with an IC(50) value 45 times lower than BA on HepG2 cells and 61 times lower than the one found for the non-tumoral Chang liver cells.

Antileishmanial Activity of Semisynthetic Lupane Triterpenoids Betulin and Betulinic Acid Derivatives: Synergistic Effects with Miltefosine

Leishmaniasis is a neglected tropical disease (NTDs), endemic in 88 countries, affecting more than 12 million people. The treatment consists in pentavalent antimony compounds, amphotericin B, pentamidine and miltefosine, among others. However, these current drugs are limited due to their toxicity, development of biological resistance, length of treatment and high cost. Thus, it is important to continue the search for new effective and less toxic treatments. The anti-Leishmania activity of sixteen semisynthetic lupane triterpenoids derivatives of betulin (BT01 to BT09) and betulinic acid (AB10 to AB16) were evaluated. Drug interactions between the active compounds and one current antileishmanial drug, miltefosine, were assessed using the fixed ratio isobologram method. In addition, effects on the cell cycle, apoptosis/necrosis events, morphology and DNA integrity were studied. The derivatives BT06 (3β-Hydroxy-(20R)-lupan-29-oxo-28-yl-1H-imidazole-1-carboxylate) and AB13 (28-(1H-imidazole-1-yl)-3,28-dioxo-lup-1,20(29)-dien-2-yl-1H-imidazole-1-carboxylate) were found to be the most active, with IC50 values of 50.8 µM and 25.8 µM, respectively. Interactions between these two compounds and miltefosine were classified as synergistic, with the most effective association being between AB13 and miltefosine, where decreases of IC50 values to 6 µM were observed, similar to the miltefosine activity alone. AB13 induced significant morphological changes, while both derivatives produced anti-proliferative activity through cell cycle arrest at the G0/G1 phase. Neither of these derivatives induced significant apoptosis/necrosis, as indicated by phosphatidylserine externalization and DNA fragmentation assays. In addition, neither of the derivatives induced death in macrophage cell lines. Thus, they do not present any potential risk of toxicity for the host cells. This study has identified the betulin derivative BT06 and the betulinic acid derivative AB13 as promising molecules in the development of new alternative therapies for leishmaniasis, including those involving combined-therapy with miltefosine.

Neighbourhood socioeconomic disadvantage and fruit and vegetable consumption: a seven countries comparison

BackgroundLow fruit and vegetable consumption is a risk factor for poor health. Studies have shown consumption varies across neighbourhoods, with lower intakes in disadvantaged neighbourhoods. However, findings are inconsistent, suggesting that socio-spatial inequities in diet could be context-specific, highlighting a need for international comparisons across contexts.This study examined variations in fruit and vegetable consumption among adults from neighbourhoods of varying socioeconomic status (SES) across seven countries (Australia, Canada, Netherlands, New Zealand, Portugal, Scotland, US).MethodsData from seven existing studies, identified through literature searches and knowledge of co-authors, which collected measures of both neighbourhood-level SES and fruit and vegetable consumption were used. Logistic regression was used to examine associations between neighbourhood-level SES and binary fruit and vegetable consumption separately, adjusting for neighbourhood clustering and age, gender and education. As much as possible, variables were treated in a consistent manner in the analysis for each study to allow the identification of patterns of association within study and to examine differences in the associations across studies.ResultsAdjusted analyses showed evidence of an association between neighbourhood-level SES and fruit consumption in Canada, New Zealand and Scotland, with increased odds of greater fruit intake in higher SES neighbourhoods. In Australia, Canada, New Zealand and Portugal, those residing in higher SES neighbourhoods had increased odds of greater vegetable intake. The other studies showed no evidence of a difference by neighbourhood-level SES.ConclusionsAcknowledging discrepancies across studies in terms of sampling, measures, and definitions of neighbourhoods, this opportunistic study, which treated data in a consistent manner, suggests that associations between diet and neighbourhood-level socioeconomic status vary across countries. Neighbourhood socioeconomic disadvantage may differentially impact on access to resources in which produce is available in different countries. Neighbourhood environments have the potential to influence behaviour and further research is required to examine the context in which these associations arise.

Measuring and testing for gender discrimination in physician pay: English family doctors

In 2008 the income of female GPs was 70%, and their wages (income per hour) were 89%, of those of male GPs. We estimate Oaxaca decompositions using OLS models of wages and 2SLS models of income and propose a set of new direct tests for within workplace gender discrimination. The direct tests are based on a comparison of the differences in income of female and male GPs in practices with varying proportions of female GPs and with female or male senior partners. These tests provide only weak evidence for discrimination. We also propose a set of indirect tests for discrimination, including a comparison of a GPs actual income with the income they report as an acceptable reward for their job. The indirect tests provide no evidence for gender discrimination within practices.

Does quality affect patients’ choice of Doctor? Evidence from England

Reforms giving users of public services choice of provider aim to improve quality. But such reforms will work only if quality affects choice of provider. We test this crucial prerequisite in the English health care market by examining the choice of 3.4 million individuals of family doctor. Family doctor practices provide primary care and control access to non‐emergency hospital care, the quality of their clinical care is measured and published and care is free. In this setting, clinical quality should affect choice. We find that a 1 standard deviation increase in clinical quality would increase practice size by around 17%.

The Influence of Primary Care Quality on Hospital Admissions for People with Dementia in England: A Regression Analysis

Objectives To test the impact of a UK pay-for-performance indicator, the Quality and Outcomes Framework (QOF) dementia review, on three types of hospital admission for people with dementia: emergency admissions where dementia was the primary diagnosis; emergency admissions for ambulatory care sensitive conditions (ACSCs); and elective admissions for cataract, hip replacement, hernia, prostate disease, or hearing loss. Methods Count data regression analyses of hospital admissions from 8,304 English general practices from 2006/7 to 2010/11. We identified relevant admissions from national Hospital Episode Statistics and aggregated them to practice level. We merged these with practice-level data on the QOF dementia review. In the base case, the exposure measure was the reported QOF register. As dementia is commonly under-diagnosed, we tested a predicted practice register based on consensus estimates. We adjusted for practice characteristics including measures of deprivation and uptake of a social benefit to purchase care services (Attendance Allowance). Results In the base case analysis, higher QOF achievement had no significant effect on any type of hospital admission. However, when the predicted register was used to account for under-diagnosis, a one-percentage point improvement in QOF achievement was associated with a small reduction in emergency admissions for both dementia (-0.1%; P=0.011) and ACSCs (-0.1%; P=0.001). In areas of greater deprivation, uptake of Attendance Allowance was consistently associated with significantly lower emergency admissions. In all analyses, practices with a higher proportion of nursing home patients had significantly lower admission rates for elective and emergency care. Conclusion In one of three analyses at practice level, the QOF review for dementia was associated with a small but significant reduction in unplanned hospital admissions. Given the rising prevalence of dementia, increasing pressures on acute hospital beds and poor outcomes associated with hospital stays for this patient group, this small change may be clinically and economically relevant.