Home- versus centre-based EXercise InTervention in patients with Heart Failure (EXIT-HF trial): A pragmatic randomized controlled trial

INTRODUCTION

The limited accessibility and the lack of adherence explain, in part, the low proportion of heart failure (HF) patients undergoing exercise-based cardiac rehabilitation (CR) programs. Home-based programs showed to be as effective and less costly than centre-based ones and might address those obstacles. Whether the evidence from international studies can be applied to our population is still unclear.

OBJECTIVES

To compare the clinical and economic impact of a home-based versus centre-based CR intervention in HF patients.

METHODS

This is a single-center, single-blind, parallel groups, non-inferiority pragmatic randomized control trial. Adult HF patients (n=120) will be randomized to either a centre-based or home-based CR program. In both groups' patients will participate in a 12-week combined CR program with 2 sessions per week. Exercise training (ExT) protocol consists of a combination of endurance [(at 60%-80% of peak oxygen uptake (VO2peak)] and resistance training (elastic bands). Those allocated to the home-based program will start with 4-5 supervised ExT sessions to familiarize themselves with the training protocol and then will continue the remaining sessions at home. The primary endpoint is the change in VO2peak at the end of the 12-week program. Secondary outcomes include alterations in circulating biomarkers, physical fitness, physical activity, quality of life, diet, psychological wellbeing, dyspnea, and cost-effectiveness analyses.

RESULTS

Patients are currently being recruited for the study. The study started in November 2019 and data collection is anticipated to be completed by December 2022. This is the first study in Portugal comparing the traditional CR program with a home-based program in HF patients. Our study results will better inform healthcare professionals who care for HF patients regarding CR.

FTIR Spectroscopy and Blood-Derived Extracellular Vesicles Duo in Alzheimer's Disease

Background

Alzheimer's disease (AD) diagnosis is difficult, and new accurate tools based on peripheral biofluids are urgently needed. Extracellular vesicles (EVs) emerged as a valuable source of biomarker profiles for AD, since their cargo is disease-specific and these can be easily isolated from easily accessible biofluids, as blood. Fourier Transform Infrared (FTIR) spectroscopy can be employed to analyze EVs and obtain the spectroscopic profiles from different regions of the spectra, simultaneously characterizing carbohydrates, nucleic acids, proteins, and lipids.

Objective

The aim of this study was to identify blood-derived EVs (bdEVs) spectroscopic signatures with AD discriminatory potential.

Methods

Herein, FTIR spectra of bdEVs from two biofluids (serum and plasma) and distinct sets of Controls and AD cases were acquired, and EVs' spectra analyzed.

Results

Analysis of bdEVs second derivative peaks area revealed differences between Controls and AD cases in distinct spectra regions, assigned to carbohydrates and nucleic acids, amides, and lipids.

Conclusions

EVs' spectroscopic profiles presented AD discriminatory value, supporting the use of bdEVs combined with FTIR as a screening or complementary tool for AD diagnosis.

Metabolomics to Study Human Aging: A Review

In the last years, with the increase in the average life expectancy, the world's population is progressively aging, which entails social, health and economic problems. In this sense, the need to better understand the physiology of the aging process becomes an urgent need. Since the study of aging in humans is challenging, cellular and animal models are widely used as alternatives. Omics, namely metabolomics, have emerged in the study of aging, with the aim of biomarker discovering, which may help to uncomplicate this complex process. This paper aims to summarize different models used for aging studies with their advantages and limitations. Also, this review gathers the published articles referring to biomarkers of aging already discovered using metabolomics approaches, comparing the results obtained in the different studies. Finally, the most frequently used senescence biomarkers are described, along with their importance in understanding aging.

Evaluation of Probable Sarcopenia's Prevalence in Hospitalized Geriatric Patients Using Ishii's Score

BACKGROUND

Sarcopenia is defined as a progressive loss of skeletal muscle mass and strength related to age and comorbidities. Worldwide sarcopenia's prevalence varies between 10-40%, being associated with functional impairment, lower quality of life, and higher mortality. Sarcopenia can be estimated based on age, calf circumference, and handgrip strength (Ishii's formula). Early diagnosis is essential because treatment with nutritional support and rehabilitation programs can prevent complications. The aim of the study was to assess the prevalence of probable sarcopenia in hospitalized patients using Ishii's score and possible associated risk factors.

METHODS

We developed an observational prospective study in a medicine inpatient ward of a Central Hospital. We applied Ishii's formula to the patients admitted to the medical ward in December 2021 and January 2022. Patients should be aged 60 or above and able to collaborate with the tests. One year later, we analyzed re-hospitalization and mortality rates. Patients with edema of the lower limbs, who were not able to follow instructions, and who were admitted exclusively for symptomatic treatment were excluded.

RESULTS

Our final sample was 49 patients (55% males, mean age 78 ± 8.88 years). Only one patient had a previous diagnosis of sarcopenia. Estimated sarcopenia´s prevalence was 73.5% N=36), higher in men and people with three or more comorbidities. In the sarcopenic group, 77% had some degree of functional dependency and positive markers for malnutrition. After one year of follow-up, we found a higher mortality rate in the sarcopenic group (44.4% against 7.6%) and a higher number of re-hospitalizations (1.03 hospitalizations per patient, against 0.31).

CONCLUSIONS

Our data showed that the prevalence of probable sarcopenia is high, but this pathology is still underdiagnosed. Traditional diagnosis is complex in some hospital settings and a simple tool such as Ishii's score can help to improve diagnostic rates. We suggest screening all patients at admission to provide early rehabilitation and nutritional support.

The Long-Term Culture of Human Fibroblasts Reveals a Spectroscopic Signature of Senescence

Aging is a complex process which leads to progressive loss of fitness/capability/ability, increasing susceptibility to disease and, ultimately, death. Regardless of the organism, there are some features common to aging, namely, the loss of proteostasis and cell senescence. Mammalian cell lines have been used as models to study the aging process, in particular, cell senescence. Thus, the aim of this study was to characterize the senescence-associated metabolic profile of a long-term culture of human fibroblasts using Fourier Transform Infrared and Nuclear Magnetic Resonance spectroscopy. We sub-cultivated fibroblasts from a newborn donor from passage 4 to passage 17 and the results showed deep changes in the spectroscopic profile of cells over time. Late passage cells were characterized by a decrease in the length of fatty acid chains, triglycerides and cholesterol and an increase in lipid unsaturation. We also found an increase in the content of intermolecular β-sheets, possibly indicating an increase in protein aggregation levels in cells of later passages. Metabolic profiling by NMR showed increased levels of extracellular lactate, phosphocholine and glycine in cells at later passages. This study suggests that spectroscopy approaches can be successfully used to study changes concomitant with cell senescence and validate the use of human fibroblasts as a model to monitor the aging process.

Study Aging by Fibroblasts Metabolome

Aging is a complex multifactorial process that, although universal, is not fully understood. It is known that the impact of aging on health is influenced by multiple factors, such as sex, race, income, and education, and that age-related diseases are strongly associated with the way people get old. The knowledge of biological aging and its comparison to the chronological age is a paramount contributor to predict the metabolic decline and the onset of age-related diseases. As aging processes observed in the whole human organism are somehow the reflection of what happens in each cell type, it is possible to study the aging process using cell lines, such as fibroblasts. Metabolomics analysis of cell lines, namely fibroblasts, gives inputs to personalized or integrative medicine; in fact, cell metabolomics is an emerging field that addresses fundamental biological and metabolic questions using modern "omic" techniques as FTIR, NMR or MS. This paper revises the relevance of using fibroblasts as cell models to study the metabolome of aging.

Potential of FTIR Spectroscopy Applied to Exosomes for Alzheimer's Disease Discrimination: A Pilot Study

Alzheimer's disease (AD) diagnosis is based on psychological and imaging tests but can also include monitoring cerebrospinal fluid (CSF) biomarkers. However, CSF based-neurochemical approaches are expensive and invasive, limiting their use to well-equipped settings. In contrast, blood-based biomarkers are minimally invasive, cost-effective, and a widely accessible alternative. Blood-derived exosomes have recently emerged as a reliable AD biomarker source, carrying disease-specific cargo. Fourier-transformed infrared (FTIR) spectroscopy meets the criteria for an ideal diagnostic methodology since it is rapid, easy to implement, and has high reproducibility. This metabolome-based technique is useful for diagnosing a broad range of diseases, although to our knowledge, no reports for FTIR spectroscopy applied to exosomes in AD exist. In this ground-breaking pilot study, FTIR spectra of serum and serum-derived exosomes from two independent cohorts were acquired and analyzed using multivariate analysis. The regional UA-cohort includes 9 individuals, clinically diagnosed with AD, mean age of 78.7 years old; and the UMG-cohort comprises 12 individuals, clinically diagnosed with AD (based on molecular and/or imaging data), mean age of 73.2 years old. Unsupervised principal component analysis of FTIR spectra of serum-derived exosomes revealed higher discriminatory value for AD cases when compared to serum as a whole. Consistently, the partial least-squares analysis revealed that serum-derived exosomes present higher correlations than serum. In addition, the second derivative peak area calculation also revealed significant differences among Controls and AD cases. The results obtained suggest that this methodology can discriminate cases from Controls and thus be potential useful to assist in AD clinical diagnosis.

Fourier-Transform Infrared Spectroscopy as a Discriminatory Tool for Myotonic Dystrophy Type 1 Metabolism: A Pilot Study

Myotonic dystrophy type 1 (DM1) is a hereditary disease characterized by progressive distal muscle weakness and myotonia. Patients with DM1 have abnormal lipid metabolism and a high propensity to develop a metabolic syndrome in comparison to the general population. It follows that metabolome evaluation in these patients is crucial and may contribute to a better characterization and discrimination between DM1 disease phenotypes and severities. Several experimental approaches are possible to carry out such an analysis; among them is Fourier-transform infrared spectroscopy (FTIR) which evaluates metabolic profiles by categorizing samples through their biochemical composition. In this study, FTIR spectra were acquired and analyzed using multivariate analysis (Principal Component Analysis) using skin DM1 patient-derived fibroblasts and controls. The results obtained showed a clear discrimination between both DM1-derived fibroblasts with different CTG repeat length and with the age of disease onset; this was evident given the distinct metabolic profiles obtained for the two groups. Discrimination could be attributed mainly to the altered lipid metabolism and proteins in the 1800–1500 cm⁻¹ region. These results suggest that FTIR spectroscopy is a valuable tool to discriminate both DM1-derived fibroblasts with different CTG length and age of onset and to study the metabolomic profile of patients with DM1.

Crystal mosaicity determined by a novel layer deconvolution Williamson–Hall method

An improvement to the classical Williamson–Hall method is developed to study several samples of AlGaN and α-MoO₃.

Multiple reflection optimization package for X-ray diffraction

New software for the simulation and fitting of 2θ–ω scans of symmetric and asymmetric reflections based on the dynamical theory of X-ray diffraction is presented.

Regular Exercise Participation Contributes to Better Proteostasis, Inflammatory Profile, and Vasoactive Profile in Patients With Hypertension

BACKGROUND

Physical exercise is a well-established strategy to control blood pressure. Nonetheless, its effects on protein homeostasis in individuals with hypertension are not clearly defined.

AIMS

Evaluate proteostasis, quality of life, and inflammation, oxidative stress, and vasoactive biomarkers in adults with hypertension regarding reported exercise habits.

METHODS

Twenty individuals were recruited in a health-care centre, 10 regular exercisers (age: 68.3 ± 4.2 years) and 10 age-matched individuals without regular exercise participation (age: 67.7 ± 5.1 years). Proteostasis and the levels of ubiquitin, heat shock protein 70 (Hsp70), endothelial nitric oxide synthase (eNOS), matrix metalloproteinases 2 (MMP-2), tissue inhibitor of MMP-2 (TIMP-2), connexin 43 (Cx43) and extracellular superoxide dismutase-3 (SOD-3) were assessed in plasma using immunoblotting techniques (western blot or slot blot) and Fourier-transform infrared spectroscopy (FTIR). Quality of life was assessed using the Short Form 36 (SF-36) version 2.0 questionnaire.

RESULTS

Significant higher levels of interleukin (IL)-6 (P = 0.014), eNOS (P = 0.011), Cx43 (P = 0.020), TIMP-2 (P = 0.038), and SOD-3 (P = 0.001), with a fold increase of 1.5, 1.2, 2.1, 1.3, and 1.2, respectively, were found in the exercise group. The overall quality of life (60.1 ± 4.3 vs. 53.2 ± 5.9, P = 0.009), as well as mental health domain (59.4 ± 7.9 vs. 50.7 ± 7.2, P = 0.024) were significantly higher in the exercise group. Multivariate analysis by FTIR showed that the age-matched group is characterized by peaks related with antiparallel β-sheet, whereas exercise group is characterized by peaks related to random coils, β-sheet, and α-helix.

CONCLUSIONS

Individuals with regular exercise participation showed better proteostasis, quality of life, inflammatory profile, antioxidant defenses, and eNOS levels.

Monitoring plasma protein aggregation during aging using conformation-specific antibodies and FTIR spectroscopy

The loss of proteostasis during aging has been well described using different models, however little is known with respect to protein aggregation levels in biofluids with aging. Therefore, the aim of this study was to assess the pattern of age-related protein aggregation in human plasma using two distinct approaches: analysis with conformation-specific antibodies and FTIR spectroscopy. The latter has been widely used in biomedical research to study protein conformational changes in health and disease. Samples from a primary care based-cohort from the Aveiro region, Portugal, were used for slot-blot analyses followed by immunodetection with conformation-specific antibodies and for the acquisition of FTIR spectra. Immunoblot analyses revealed an age-dependent evolution of the protein conformational profile in human plasma, towards a decrease in prefibrillar oligomers and an increase in fibrillar structures. This finding was also supported by PLS-R multivariate analysis of FTIR data, where a positive correlation between the age of the donors and secondary structure of plasma proteins could be observed. Samples from younger donors are characterized by antiparallel β-sheet-containing structures while intermolecular β-sheets characterized older samples. Exclusion of age-associated co-morbidities improved the correlation between protein conformational profiles and aging. The results reveal structural changes in human plasma proteins from middle to old age, confirming the age-associated changes in protein aggregation, and support the applicability of FTIR as a reliable approach to study proteostasis during aging.

Frailty in cardiovascular disease: Screening tools

Cardiovascular disease (CVD) is the leading cause of death in developed countries and disproportionately affects older adults. Frailty is a complex clinical syndrome with multiple causes and contributing factors in which there is increased vulnerability when exposed to a minor stressor and increased risk for adverse outcomes, such as disability, hospitalization and mortality. Frailty is an important prognostic factor in patients with CVD, and so identifying this feature when assessing these patients may help to individually tailor cardiovascular treatment. The first step is to identify frailty. Several tools have been validated as screening methods for frailty. However, they diverge with regard to complexity, nature, feasibility and the outcome they can predict. The aim of this review is to describe the available screening tools for frailty and to examine their usefulness in patients with CVD.

The incidence of bent dorsal fins in free-ranging cetaceans

Laterally bent dorsal fins are rarely observed in free-ranging populations of cetaceans, contrary to captivity, where most killer whale Orcinus orca adult males have laterally collapsed fins. This topic has been poorly explored, and data/information on its occurrence and possible causes are limited. The present study: (i) undertakes a review of the available information on bent dorsal fins in free-ranging cetaceans, and updates it with new records, (ii) reports on the proportion of bent fins in different study populations, and (iii) discusses possible causes. An empirical approach based on bibliographic research and compilation of 52 new records collected worldwide resulted in a total of 17 species of cetaceans displaying bent dorsal fins. The species with the highest number of records (64%) and from most locations was O. orca. On average, individuals with bent dorsal fins represent < 1% of their populations, with the exception of false killer whales Pseudorca crassidens and O. orca. While line injuries associated with fisheries interactions may be the main cause for P. crassidens, and the vulnerability to health issues caused by the evolutionary enlargement of the fin may be the cause for O. orca adult males, factors contributing to this abnormality for other species are still unclear. The occurrence of bent dorsals could be influenced by a set of variables rather than by a single factor but, irrespective of the cause, it is suggested that it does not directly affect the animals' survivorship. While still rare in nature, this incident is more common (at least 101 known cases) and widespread (geographically and in species diversity) than hypothesized, and is not confined only to animals in captive environments. Investigation into the occurrence of bent fins may be an interesting avenue of research.

Proteomic profile of susceptible and multidrug-resistant clinical isolates of Escherichia coli and Klebsiella pneumoniae using label-free and immunoproteomic strategies

Infectious diseases caused by multidrug-resistant (MDR) Enterobacteriaceae have exponentially increased in the past decade, and are a major concern in hospitals. In the first part of the work, we compared the proteome profile of MDR and susceptible clinical isolates of Escherichia coli and Klebsiella pneumoniae in order to identify possible biological processes associated with drug resistance and susceptible phenotypes, using a label-free approach. In the second part, we used an immunoproteomics approach to identify immunoreactive proteins in the same isolates. A total of 388 and 377 proteins were identified in MDR and susceptible E. coli, respectively, evidencing that biological processes related to translation are upregulated in E. coli MDR, while there is an upregulation of processes related to catalytic activity in K. pneumoniae MDR. Both MDR strains show downregulation of processes related to amino acid activation and tRNA amino-acylation. Our data also suggest that MDR strains have higher immunoreactivity than the susceptible strains. The application of high-throughput mass spectrometry (MS) and bioinformatics to the study of modulation of biological processes might shed light on the characterization of multidrug resistance in bacteria.

[Predictors of changes in functional capacity on a cardiac rehabilitation program]

INTRODUCTION

The effectiveness of cardiac rehabilitation programs (CRP) strongly influences the recovery of functional capacity (FC), resulting in improved prognosis and survival.

OBJECTIVE

To determine the cardiovascular risk factors that predict changes in FC in patients on CRP.

METHODS

We performed a cross-sectional descriptive retrospective study of patients who began a CRP between January 2008 and December 2013. The dependent variable was changes in FC estimated in metabolic equivalents (METs) achieved in stress testing at the beginning and end of the phase II program. The independent variables were age, gender, dyslipidemia, diabetes, smoking, body mass index, physical activity level and reason for referral to the CRP.

RESULTS

The sample included 1399 patients, of whom 1125 (80.4%) completed the program. FC improved in most patients (93%), with a mean gain of 1.45 ± 1.19 METs. Patients aged 45 -65 and over 65 years achieved a greater increase in FC compared with other age groups. Patients admitted to the CRP after coronary artery bypass graft surgery obtained a greater improvement in FC compared to patients with acute coronary syndrome. Non-diabetic patients benefited more than diabetic patients. No significant differences were seen between the groups in the other variables.

CONCLUSION

This study highlights the need for new and individualized approaches in certain subgroups of patients on CRP.

Analysis of the stability of InGaN/GaN multiquantum wells against ion beam intermixing

Ion-induced damage and intermixing was evaluated in InGaN/GaN multi-quantum wells (MQWs) using 35 keV N(+) implantation at room temperature. In situ ion channeling measurements show that damage builds up with a similar trend for In and Ga atoms, with a high threshold for amorphization. The extended defects induced during the implantation, basal and prismatic stacking faults, are uniformly distributed across the quantum well structure. Despite the extremely high fluences used (up to 4 × 10(16) cm(-2)), the InGaN MQWs exhibit a high stability against ion beam mixing.

Comparative proteomic analyses of urine from rat urothelial carcinoma chemically induced by exposure to N-butyl-N-(4-hydroxybutyl)-nitrosamine

Bladder cancer is estimated to be the ninth most common malignancy with a high rate of recurrence and progression despite therapy, early diagnosis being crucial for timely intervention.

Do mites evolving in alternating host plants adapt to host switch?

A fluctuating environment may be perceived as a composition of different environments, or as an environment per se, in which it is the fluctuation itself that poses a selection pressure. If so, then organisms may adapt to this alternation. We tested this using experimental populations of spider mites that have been evolving for 45 generations in a homogeneous environment (pepper or tomato plants), or in a heterogeneous environment composed of an alternation of these two plants approximately at each generation. The performance (daily oviposition rate and juvenile survival) of individuals from these populations was tested in each of the homogeneous environments, and in two alternating environments, one every 3 days and the other between generations. To discriminate between potential genetic interactions between alleles conferring adaptation to each host plant and environmental effects of evolving in a fluctuating environment, we compared the performance of all lines with that of a cross between tomato and pepper lines. As a control, two lines within each selection regime were also crossed. We found that crosses between alternating lines and between pepper and tomato lines performed worse than crosses between lines evolving in homogeneous environments when tested in that environment. In contrast, alternating lines performed either better or similarly to lines evolving in homogeneous environments when tested in a fluctuating environment. Our results suggest that fluctuating environments are more than the juxtaposition of two environments. Hence, tests for adaptation of organisms evolving in such environments should be carried out in fluctuating conditions.

Que Fatores Determinam os Níveis de Atividade Física após Programa de Reabilitação Cardíaca?

Introduction: The Cardiac Rehabilitation Programs have gained tremendous importance in the prevention of cardiovascular disease and it’s a challenge to ensure the practice of regular exercise during and after the supervised program. The aim of this study was to determine the factors that influence the physical activity habits at 12 months after the Cardiac Rehabilitation Program.Material and Methods: Prospective study, including 580 patients with ischemic heart disease who were consecutively oriented for Cardiac Rehabilitation Program at Cardiovascular Prevention and Rehabilitation Unit of Centro Hospitalar do Porto, between January 2008 and June 2011. Physical activity levels were measured with International Physical Activity Questionnaire which was calculated at the beginning of the program, 3 and 12 months later. The following variables were chosen and tested as potential determinants of physical activity habits of 12 months after program: age; sex; modifiable risk factors; functional capacity (achieved in treadmill stress test); laboratory analysis (HbA1c, lipid profile, C-Reactive Protein and Brain Natriuretic Peptide). A linear regression analysis was carried to identify the significant determinants and to find the best model adjustment.Results: Advanced age, female gender, functional capacity and low levels of physical activity prior to the Cardiac Rehabilitation Program, as well as a weak evolution of the International Physical Activity Questionnaire during the program were the best univariable predictors of a less favourable evolution of the International Physical Activity Questionnaire during 12 months of follow-up. A multivariable linear regression analysis showed that the best explanatory model included age, gender and evolution of the International Physical Activity Questionnaire during the supervised program (R2 Adj. = 0.318; f = 60.62, p < 0.001).Conclusion: The identification of certain subgroups of patients with lower tendency toward physical activity is beneficial to enable timely and individualized strategies to maximize the therapeutic and preventive potential of the Cardiac Rehabilitation Programs.

[What factors determine the levels of physical activity after cardiac rehabilitation program?]

INTRODUCTION

The Cardiac Rehabilitation Programs have gained tremendous importance in the prevention of cardiovascular disease and it's a challenge to ensure the practice of regular exercise during and after the supervised program. The aim of this study was to determine the factors that influence the physical activity habits at 12 months after the Cardiac Rehabilitation Program.

MATERIAL AND METHODS

Prospective study, including 580 patients with ischemic heart disease who were consecutively oriented for Cardiac Rehabilitation Program at Cardiovascular Prevention and Rehabilitation Unit of Centro Hospitalar do Porto, between January 2008 and June 2011. Physical activity levels were measured with International Physical Activity Questionnaire which was calculated at the beginning of the program, 3 and 12 months later. The following variables were chosen and tested as potential determinants of physical activity habits of 12 months after program: age; sex; modifiable risk factors; functional capacity (achieved in treadmill stress test); laboratory analysis (HbA1c, lipid profile, C-Reactive Protein and Brain Natriuretic Peptide). A linear regression analysis was carried to identify the significant determinants and to find the best model adjustment.

RESULTS

Advanced age, female gender, functional capacity and low levels of physical activity prior to the Cardiac Rehabilitation Program, as well as a weak evolution of the International Physical Activity Questionnaire during the program were the best univariable predictors of a less favourable evolution of the International Physical Activity Questionnaire during 12 months of follow-up. A multivariable linear regression analysis showed that the best explanatory model included age, gender and evolution of the International Physical Activity Questionnaire during the supervised program (R2 Adj. = 0.318; f = 60.62, p < 0.001).

CONCLUSION

The identification of certain subgroups of patients with lower tendency toward physical activity is beneficial to enable timely and individualized strategies to maximize the therapeutic and preventive potential of the Cardiac Rehabilitation Programs.

Optical and structural properties of an Eu implanted gallium nitride quantum dots/aluminium nitride superlattice

GaN/AIN structures made of GaN quantum dots (QDs) separated by AIN spacer layers, were doped with Europium by ion implantation. Rutherford Backscattering/Channelling measurements showed that Eu is incorporated mainly on near-substitutional cation sites within the superlattice region. Only slight deterioration of the crystal quality and no intermixing of the different layers are observed after implantation and annealing. After thermal annealing, photoluminescence associated with Eu3+ ions was observed. From its behaviour under different photon energy excitation and sample temperature we concluded that the Eu-related emitting centres are located inside the GaN QDs or dispersed in the GaN and AIN buffer or spacer layers. The 624 nm PL line, associated with Eu-doped GaN QDs, shows very low thermal quenching, suggesting recombination of confined carriers through rare-earth ion excitation.

Reproductive barriers between two sympatric beetle species specialized on different host plants

Knowledge on interspecific pre- and post-zygotic isolation mechanisms provides insights into speciation patterns. Using crosses (F(1) and backcrosses) of two closely related flea beetles species, Altica fragariae and A. viridicyanea, specialized on different hosts in sympatry, we measured: (a) the type of reproductive isolation and (b) the inheritance mode of preference and host-specific performance, using a joint-scaling test. Each species preferred almost exclusively its host plant, creating strong prezygotic isolation between them, and suggesting that speciation may occur at least partly in sympatry. Reproductive isolation was intrinsic between females of A. fragariae and either A. viridicyanea or F(1) males, whereas the other crosses showed ecologically dependent reproductive isolation, suggesting ecological speciation. The genetic basis of preference and performance was at least partially independent, and several loci coded for preference, which limits the possibility of sympatric speciation. Hence, both ecological and intrinsic factors may contribute to speciation between these species.

Population genetics and social organization of the sperm whale (Physeter macrocephalus) in the Azores inferred by microsatellite analyses

In the northeast Atlantic Ocean, the archipelago of the Azores is frequented by female–offspring groups of sperm whales ( Physeter macrocephalus L., 1758), as well as large males. The Azores apparently constitute both a feeding ground and a reproduction site. Little is known about the population and group structure of sperm whales in the area. We analysed 151 sloughed skin and biopsy samples collected from 2002 to 2004. Molecular analyses involved genetic tagging using 11 microsatellite loci and molecular sexing. Our objectives were to determine the population genetic structure, compare relatedness within and between social groups, infer kinship, and estimate the age of males at dispersal. Results suggest that individuals visiting the archipelago of the Azores belong to a single population. High genetic diversity and absence of inbreeding suggest that the population is recovering from whaling. Individuals sampled in close association are highly related, as well as those observed in the same area on the same day, suggesting that secondary social groups (i.e., the union of primary social units) are largely but not exclusively composed of relatives. Probable mother–offspring and full-sibling pairs were identified. Age of males at dispersal was estimated at 16.6 years, which was well above previous estimates for this species.

Adaptation in a spider mite population after long-term evolution on a single host plant

Evolution in a single environment is expected to erode genetic variability, thereby precluding adaptation to novel environments. To test this, a large population of spider mites kept on cucumber for approximately 300 generations was used to establish populations on novel host plants (tomato or pepper), and changes in traits associated to adaptation were measured after 15 generations. Using a half-sib design, we investigated whether trait changes were related to genetic variation in the base population. Juvenile survival and fecundity exhibited genetic variation and increased in experimental populations on novel hosts. Conversely, no variation was detected for host choice and developmental time and these traits did not evolve. Longevity remained unchanged on novel hosts despite the presence of genetic variation, suggesting weak selection for this trait. Hence, patterns of evolutionary changes generally matched those of genetic variation, and changes in some traits were not hindered by long-term evolution in a constant environment.

Pattern of right ventricular pressure fall and its modulation by afterload

Pattern of right ventricular pressure (RVP) fall and its afterload dependence were examined by analyzing ventricular pressure curves and corresponding pressure dP/dt phase planes obtained in both ventricles in the rat heart in situ. Time and value of dP/dt(min), and the time constant tau were measured at baseline and during variable RV afterload elevations, induced by beat-to-beat pulmonary trunk constrictions. RVP and left ventricular pressure (LVP) decays were divided into initial accelerative and subsequent decelerative phases separated by corresponding dP/dt(min). At baseline, LVP fall was decelerative during 4/5 of its course, whereas only 1/3 of RVP decay occurred in a decelerative fashion. During RV afterload elevations, the absolute value of RV-dP/dt(min) and RV-tau increased, whilst time to RV dP/dt(min) decreased. Concomitantly, the proportion of RVP decay following a decelerative course increased, so that in highly RV afterloaded heartbeats RVP fall became more similar to LVP fall. In conclusion, RVP and LVP decline have distinct patterns, their major portion being decelerative in the LV and accelerative in the RV. In the RV, dP/dt(min), tau and the proportional contribution of accelerative and decelerative phases for ventricular pressure fall are afterload-dependent. Consequently, tau evaluates a relatively much shorter segment of RVP than LVP fall.

Plant feeding by a predatory mite inhabiting cassava

Plant feeding by arthropod predators may strongly affect the dynamics of bi-and tri-trophic interactions. We tested whether a predatory mite, Typhlodromalus aripo, feeds upon its host plant, cassava. This predator species is an effective biological control agent of Monoychellus tanajoa (the cassava green mite or CGM) a herbivorous mite specific to cassava. We developed a technique to detect plant feeding, based on the use of a systemic insecticide. We found that T. aripo feeds upon plant-borne material, while other predatory mite species, Neoseiulus idaeus and Phytoseiulus persimilis, do not. Subsequently, we measured survival of juveniles and adult females of T. aripo and N. idaeus, both cassava-inhabiting predator species, on cassava leaf discs. Survival of T. aripo was higher than that of N. idaeus. Thus, T. aripo was able to withstand longer periods of prey scarcity. Because CGM populations fluctuate yearly and are heterogeneously distributed within plants, plant feeding may facilitate the persistence of populations of T. aripo in cassava fields and its control of CGM outbreaks.