Biomedical subjects

Carla Rego

Publications and source records attributed to Carla Rego.

9 recordsLinked to original sources

PubMed2026

Stability in the face of global decline: a 20-year study of arthropods in an oceanic archipelago.

Insect declines are of global concern, yet no long-term ecological studies (LTER) have confirmed this trend on islands. This study utilises the first available LTER data on island arthropods, targeting epigeal and canopy species from the Azores Archipelago (Portugal), and covering over 20 years in three distinct sampling events from 30 standard sites. We investigate changes in abundance, biomass, and species richness within native forest arthropod communities, focusing on the proportions of endemic and introduced species, and temporal patterns among single-island endemics and forest-dependent endemics. Results reveal significant temporal variability, but overall abundance, biomass, and species richness remain stable across endemic and native non-endemic taxa. Among the species studied, 28% declined, 17% increased, and 55% showed no significant differences. Exotic invasions and related extinctions appear minimal. Forest-dependent endemic species declined below anticipated levels, suggesting that the extinction debt for these species may be less severe than initially expected. Nonetheless, some forest specialists have declined significantly, and seven species, not seen over 20 years, are considered to be extinct. The three-decade-long conservation of Azorean native forests may have contributed to the stability of some populations, thus these findings underscore the need for continued and enhanced conservation efforts of insular forest-associated diversity.

Animals↗

PubMed2006

Quantitative genetics of speciation: additive and non-additive genetic differentiation between Drosophila madeirensis and Drosophila subobscura.

The role of dominance and epistasis in population divergence has been an issue of much debate ever since the neoDarwinian synthesis. One of the best ways to dissect the several genetic components affecting the genetic architecture of populations is line cross analysis. Here we present a study comparing generation means of several life history-traits in two closely related Drosophila species: Drosophila subobscura, D. madeirensis as well as their F1 and F2 hybrids. This study aims to determine the relative contributions of additive and non-additive genetic parameters to the differentiation of life-history traits between these two species. The results indicate that both negative dominance and epistatic effects are very important in the differentiation of most traits. We end with considerations about the relevance of these findings for the understanding of the role of non-additive effects in speciation.

Animals↗

PubMed2006

Symmetry breaking in interspecific Drosophila hybrids is not due to developmental noise.

Hybrids from crosses of different species have been reported to display decreased developmental stability when compared to their pure species, which is conventionally attributed to a breakdown of coadapted gene complexes. Drosophila subobscura and its close relative D. madeirensis were hybridized in the laboratory to test the hypothesis that genuine fluctuating asymmetry, measured as the within-individual variance between right and left wings that results from random perturbations in development, would significantly increase after interspecific hybridization. When sires of D. subobscura were mated to heterospecific females following a hybrid half-sib breeding design, F1 hybrid females showed a large bilateral asymmetry with a substantial proportion of individuals having an asymmetric index larger than 5% of total wing size. Such an anomaly, however, cannot be plainly explained by an increase of developmental instability in hybrids but is the result of some aberrant developmental processes. Our findings suggest that interspecific hybrids are as able as their parents to buffer developmental noise, notwithstanding the fact that their proper bilateral development can be harshly compromised. Together with the low correspondence between the co-variation structures of the interindividual genetic components and the within-individual ones from a Procrustes analysis, our data also suggest that the underlying processes that control (genetic) canalization and developmental stability do not share a common mechanism. We argue that the conventional account of decreased developmental stability in interspecific hybrids needs to be reappraised.

Animals↗

PubMed2004

Low birth weight and cardiovascular risk factors at school age.

BACKGROUND: Many epidemiological studies show a strong association between nutritional status at birth and later chronic diseases, particularly cardiovascular diseases. These results seem to confirm fetal programming regarding risk factors and future diseases such as diabetes, hypertension, cardiovascular disease and kidney dysfunction. The aim of the present study is to evaluate, in a group of low-birth-weight (LBW) newborns, the influence of nutritional status at birth on blood pressure and lipid profile at school age. METHODS: A group of low birth weight newborns (n = 30) and a group with appropriate gestational age (AGA) (n = 26) were prospectively evaluated from birth up to 84 months of age. Nutritional status was evaluated at every observation and blood pressure and lipid profile were measured at 84 months according to international recommendations. RESULTS: A catch-up growth was observed in the LBW group during the first two years of life, stature at 84 months being similar in both groups (AGA = -0.3 +/- 0.8 Z-score; LBW = -0.4 +/- 1.1 Z-score). When results are grouped according to weight gain between birth and 84 months of life, and taking account of breast-feeding duration, the LBW children show higher values, with significant differences in diastolic blood pressure between groups in those with greater weight gain (AGA = 88.8 +/- 5.8% of 50th percentile; LBW = 101.2 +/- 5.8% of 50th percentile; p < or = 0.01). Regarding lipid profile, no differences were found except for apolipoprotein A, with lower values in the LBW group (LBW = 125.6 +/- 4.1 mg/dl; AGA = 143.4 +/- 24.6 mg/dl; p < or = 0.05). CONCLUSIONS: Low birth weight newborns are at higher risk of future cardiovascular disease as they show higher blood pressure values compared to those with appropriate nutritional status at birth. These results are more evident in those individuals with greater weight gain, irrespective of breastfeeding duration. All efforts should be directed towards environmental factors that can negatively influence the health and nutritional status of pregnant women in order to reduce the prevalence of LBW newborns.

Cardiovascular Diseases↗

PubMed2004

Convergence to a novel environment: comparative method versus experimental evolution.

Laboratory adaptation allows researchers to contrast temporal studies of experimental evolution with comparative studies. The comparative method is here taken to mean the inference of microevolutionary processes from comparisons among contemporaneous populations of diverse origins, from one or multiple species. The data contrasted here come from Drosophila subobscura populations that were introduced to the laboratory at several different times and from two different locations. Two questions were addressed. First, can we correctly infer evolutionary dynamics from comparative data collected simultaneously from disparate populations? In most cases, we could, except for the character of starvation resistance. Second, are the evolutionary dynamics inferred from the comparative approach similar to those revealed by temporal studies of experimental evolution? For fecundity characters, they were. Overall the results show that both comparative and temporal studies are useful, though the former can be uninformative for characters with complex evolutionary trajectories.

Adaptation, Biological↗

PubMed2003

Influence of apolipoprotein e polymorphism on cardiovascular risk factors in obese children.

AIM: The main objective of the study was to determine whether risk factors associated with obesity are influenced by genetic variation of apolipoprotein E (ApoE). METHODS: 81 obese children (mean age 9.4 +/- 2.8 years) and an age-matched control group were included. Body composition, lipid profile, and glucose and insulin levels were evaluated according to international recommendations, and the blood pressure was measured by an oscillometric method. RESULTS: The calculated frequencies of the ApoE alleles *2, *3, and *4 (0.04, 0.88 and 0.08) in obese children were similar to those of eutrophic age-matched controls (0.07, 0.82, and 0.11) and fitted the range of variation generally observed in southern European populations. Age, anthropometric parameters, body fat mass, and blood pressure were similar in E2/3, E3/3 and E4/3 genotypes. Total/high-density lipoprotein cholesterol and low-density lipoprotein/high-density lipoprotein cholesterol ratios were higher in the E4/3 group as compared with E3/3 (p < 0.01) and E2/3 (p < 0.05) groups. No differences concerning clusters of risk factors were observed among the three genotypes. No associations were found between ApoE polymorphism and glucose levels (fasting and at 2 h) and between fasting insulin levels and HOMA(IR) results. Higher levels of fasting and 2-hour insulin and higher HOMA(IR) values were significantly associated with a higher fat mass. CONCLUSIONS: ApoE polymorphism seems to influence some lipid profile abnormalities associated with obesity in childhood. However, clustering of risk factors and insulin resistance seem not to be dependent on ApoE polymorphism.

Apolipoproteins E↗

PubMed2002

Bony density in adolescents after surgical repair of tetralogy of fallot: a comparative study with healthy adolescents.

BACKGROUND: Adverse influences arising in fetal life or immediately after birth have a permanent effect on body structure, physiology and metabolism. Evidence is now accumulating that programming of bone growth might be an important contributor to the later risk of osteoporosis. Long-term morbidity and mortality associated with retralogy of Fallot is not completely known. The aim of the present study was to evaluate the state of the bones in adolescents after surgical repair of tetralogy of Fallot, so as to ascertain any possible repercussions of the disease on bone mineralization. MATERIAL AND METHODS: We studied 34 adolescents with repaired tetralogy of Fallot, between the ages of 11 and 18 years, to establish their nutritional status, in terms of height, weight, and skinfolds, their body composition using an anthropometric method, their sexual maturity according to Tanner, and their food-habits as based on 24-hour recall. Bone density was evaluated by lumbar dual-energy X-ray absorptiometry. We included 34 healthy eutrophic adolescents, matched for gender and age, as controls. RESULTS: No significant differences were observed between the patients and their controls concerning nutritional status, body composition, total energy intake and nutritional supply in macronutrients, calcium, phosphorus, magnesium and vitamin D. Bone mineral density, expressed in Z-score and g/cm2, was significantly higher in patients with tetralogy of Fallot (p < 0.01). The age at the time of the first surgical procedure, or at complete surgical repair, and the total number of surgical procedures, had no significant influence on nutritional status or bone mineralization. Gender, chronological age, sexual maturity and the index of body mass are the major determinants of bone density for both samples. Obese adolescents with repaired tetralogy of Fallot had a significantly higher bone density (p < 0.05) compared to undernourished or euthrophic patients. CONCLUSIONS: Being born with tetralogy of Fallot has no significant repercussion, by the stage of adolescence, on nutritional status, pubertal progression, and accretion of bone minerals subsequent to surgical repair. Nutritional status is the major influence on the accretion of bone mass.

Adolescent↗

PubMed2002

Blood pressure and genetic and biological markers in a pediatric population.

BACKGROUND: It is universally accepted that atherosclerosis originates in childhood and that high LDL and low HDL serum cholesterol, hypertension and obesity are some of the main risk factors. In the past few years, increasing importance has been attributed to the deleterious effect of reactive oxygen species (ROS) on lipids, on the endothelial lining of arteries, and on the occurrence of cardiovascular disease. The relationship between blood pressure, active renin (AR) and the genetic polymorphism of haptoglobin in a population of adolescents was studied using pro-oxidant status markers, and also using some enzyme systems involved in the antioxidant defense mechanism of the body. METHODS: 51 healthy children, 9 to 12 years of age, were evaluated. The following examinations were performed: nutritional status (weight, height, skinfolds and body mass index) and blood pressure; note was made of any family history of cardiovascular disease. The biological parameters assessed by internationally recommended methods included haptoglobin phenotyping and determination of active renin (AR), the Na+/Li+ countertransport system (Na+/Li+ CTR), antioxidant enzyme systems, metahemoglobin reductase (MetHbRed) and transmembrane reductase (TMR) and indicators of oxidative status, namely activity of plasma epinephrine oxidase (EO) and erythrocytic acid phosphatase (LMW-PTP). RESULTS: The study of the behavior of AR, Na+/Li+ CTR, EO and erythrocyte enzymes (MetHbRed, TMR and LMW-PTP) according to haptoglobin genetic phenotypes, only showed a significant difference for renin, with lower values for allele 1 carriers (homo- and heterozygous) (p < 0.05). There were no significant differences in blood pressure as regards the haptoglobin genetic phenotypes. The analysis of the behavior of the same biochemical parameters considering a family history of cardiovascular disease (CVD) showed higher values of TMR and lower values of EO in individuals with negative family history. Linear multiple regression showed some biological (Na+/Li+ CTR and MetHbRed) and genetic parameters (haptoglobin and family history of cardiovascular disease) to be stronger determinants of systolic blood pressure. CONCLUSIONS: It would appear that there is a tendency for some intermediate biochemical phenotypes to express early on in childhood in individuals with a family history of CVD, which would point to an evident genetic disposition towards this type of pathology.

Biomarkers↗

PubMedDate not supplied

Genetic polymorphisms of angiotensin-I converting enzyme, haptoglobin and angiotensinogen and oxidative stress parameters in 12 to 15-year-old adolescents.

BACKGROUND: Angiotensin-converting enzyme (ACE) I/D, haptoglobin (Hp) 1/2 and angiotensinogen (AGT) M235T gene polymorphisms have been associated with the risk of various cardiovascular conditions. Oxidative stress and reactive oxygen species have also been implicated in endothelial injury. In a randomly selected sample of healthy adolescents, we studied the relationship between these genetic polymorphisms and somatic characteristics, blood pressure and certain biochemical markers of oxidative stress. METHODS: A sample of 49 healthy adolescents were genotyped for ACE I/D, Hp 1/2 and AGT M235T polymorphisms. Anthropometric parameters, blood pressure and lipid profile were evaluated using internationally recommended methods. Serum ACE activity and oxidative stress markers were determined either by spectrophotometric methods or with commercially available kits. RESULTS: Males had higher values for ACE activity than females (p < 0.01). The haptoglobin Hp allele 1 and the ACE D allele were associated with higher ACE activity (p < 0.05 and p < 0.001). ACE activity was similar between AGT genotypes. Higher levels of MDA-LDL/Apo B were observed in individuals with both ACE DD and Hp 2-2 genotypes. Carriers of the AGT TT genotype showed higher diastolic blood pressures than other AGT genotypes. CONCLUSION: Carriers of both ACE DD and Hp 2-2 genotypes have a higher pro-oxidant status and AGT TT carriers have higher diastolic blood pressures, which may indicate a higher risk for development of hypertension in these individuals.

Adolescent↗