Browsing by Author "Cruz, C."
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- Benefits of pulmonary rehabilitation in patients with chronic obstructive pulmonary disease and interstitial lung disease with the same dyspnea severityPublication . Pedro, P. I.; Santos, L. Maia; Forte, C. Braço; Dias, A.; Cruz, C.; Rodrigues, Fabio RibeiroPulmonary rehabilitation (PR) programs improve exercise capacity in patients with chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD), but few studies compare results between both pathologies. It is not yet obvious whether gains in 6-min walk distance (6MWD) accomplished by patients with ILD are comparable to those with COPD, because existing studies have yielded conflicting results. There are studies that reported similar improvement in exercise tolerance and quality of life in patients with COPD and non-obstructive lung disease. However, the duration of benefit may be shorter lived than that seen after PR among patients with COPD. Also, the type and severity of ILD may also influence outcomes of PR. A recent systematic review and meta-analysis on the impact of pulmonary rehabilitation in patients with idiopathic pulmonary fibrosis showed a growing body of evidence of its benefit in exercise tolerance and quality of life. The aim of our study was to evaluate the effect of PR on exercise capacity using 6-min walk test (6MWT) within and between COPD and ILD patients. Outcomes were the change in 6MWD and maximum heart rate (HRmax), and the comparison of these changes between groups according to dyspnea level classified by modified Medical Research Council scale (mMRC).
- Body fat and poor diet in breast cancer womenPublication . Amaral, P.; Miguel, R.; Mehdad, A.; Cruz, C.; Grillo, I. Monteiro; Camilo, Maria; Ravasco, P.Background: Breast cancer is the most common cancer in women worldwide. Differences in breast cancer incidence suggest a significant role of environmental factors in the aetiology: obesity, central adiposity, excess body fat and some dietary factors have been suggested as risk factors. This pilot study aimed to analyse the pattern of nutritional status, body fat, and the usual dietary intake among women diagnosed with breast cancer, consecutively referred to the Radiotherapy Department of the University Hospital Santa Maria. Patients and methods: Throughout 2006, 71 consecutive women with breast cancer were included. Evaluations: weight (kg) & height (m), determined with a SECA® floor scale + stadiometer to calculate body mass index (BMI), waist circumference, percentage body fat with bipolar hand-held bio-impedance analysis (BF-306®), Food Frequency Questionnaire validated for the Portuguese population to assess the usual dietary intake. Frequency analysis and Mann-Whitney U test were used to evaluate prevalence and associations. Results: Mean age was 60 ± 12 (36-90) years. Invasive ductal carcinoma was the most frequent histology (68%), p < 0.05. Most patients were in stage I (30%) or stage IIA (25%) of disease vs IIB (10%), IIIB (4%), IV (4%) or others (21%), p < 0.05. Regarding nutritional status, 82% were overweight/obese; 89% of patients had a %body fat mass above the maximum limit of 30% vs only 8 (11%) with %body fat within normal range (p < 0.002); 62% pts had a waist circumference > 88 cm (prevalence analysis: p < 0.04), and 61% of pts had gained weight after diagnosis. Univariate analysis did not show any association between histology, BMI, %body fat and waist circumference; by multivariate analysis there was an association between higher BMI, %body fat & aggressive histologies (p < 0.005). Food frequency analysis showed a low intake of vegetables and wholegrain cereals rich in complex carbohydrates (sources of fibre and phytochemicals), of fatty fish & nuts, primary sources of n-3 PUFA’s and a high intake of saturated fat; more aggressive histologies were correlated with low intake of green leafy vegetables (p = 0.05) and n-3 fatty acids food sources (p = 0.01). Conclusions: Our findings show a vast prevalence & homogeneous pattern of overweight/obesity, excessive body and abdominal fat, as well as weight gain after diagnosis, combined with diets deficient in protective nutrients. Further investigation is warranted as cancer rates in Portugal continue to increase.
- C allocation to the fungus is not a cost to the plant in ectomycorrhizaePublication . Corrêa, A.; Gurevitch, J.; Martins-Loução, M. A.; Cruz, C.Mycorrhizal benefit to plants is most frequently evaluated through growth differences between mycorrhizal (M) and non-mycorrhizal (NM) plants. These growth differences are often considered to be due to differences in belowground C expenditure, or in cost efficiency, i.e. amount of nutrients acquired per C expended. We searched published reports for relations between plant growth and belowground C allocation, C use efficiency, or nutrient uptake, in ectomycorrhizal (ECM) versus non-mycorrhizal plants. We found a similar number of cases of negative, null or positive effects of ECM on plant growth. These effects were not correlated with differences on belowground C allocation or C use efficiency between M and NM plants. In contrast, they were very strongly correlated with mycorrhizal effects on plant N gain. A comprehensive analysis of the published data therefore provided evidence that C is an excess, rather than a costly, resource, and that the outcome of the symbiosis depends only on whether mycorrhizae result in increased or decreased nutrient acquisition compared with NM plants, and not on cost efficiency differences between M and NM plants. Consequences of this finding for the regulation of resource exchange between symbionts and the nature of the symbiosis are discussed.
- How does glutamine synthetase activity determine plant tolerance to ammonium?Publication . Cruz, C.; Bio, A. F. M.; Dominguez-Valdivia, M. D.; Aparicio-Tejo, P. M.; Lamsfus, C.; Martins-Loução, M. A.The wide range of plant responses to ammonium nutrition can be used to study the way ammonium interferes with plant metabolism and to assess some characteristics related with ammonium tolerance by plants. In this work we investigated the hypothesis of plant tolerance to ammonium being related with the plants’ capacity to maintain high levels of inorganic nitrogen assimilation in the roots. Plants of several species (Spinacia oleracea L., Lycopersicon esculentum L., Lactuca sativa L., Pisum sativum L. and Lupinus albus L.) were grown in the presence of distinct concentrations (0.5, 1.5, 3 and 6 mM) of nitrate and ammonium. The relative contributions of the activity of the key enzymes glutamine synthetase (GS; under light and dark conditions) and glutamate dehydrogenase (GDH) were determined. The main plant organs of nitrogen assimilation (root or shoot) to plant tolerance to ammonium were assessed. The results show that only plants that are able to maintain high levels of GS activity in the dark (either in leaves or in roots) and high root GDH activities accumulate equal amounts of biomass independently of the nitrogen source available to the root medium and thus are ammonium tolerant. Plant species with high GS activities in the dark coincide with those displaying a high capacity for nitrogen metabolism in the roots. Therefore, the main location of nitrogen metabolism (shoots or roots) and the levels of GS activity in the dark are an important strategy for plant ammonium tolerance. The relative contribution of each of these parameters to species tolerance to ammonium is assessed. The efficient sequestration of ammonium in roots, presumably in the vacuoles, is considered as an additional mechanism contributing to plant tolerance to ammonium nutrition.
- International exchange program between medical schools : the relevance of a clinical research training in nutritionPublication . Ferencova, J.; Krajnak, S.; Chaves, M.; Cruz, C.; Grillo, I. Monteiro; Camilo, M.ª E.; Ravasco, P.
- Nitrogen assimilation and transport in carob plantsPublication . Cruz, C.; Lips, S. H.; Martins-Loução, M. A.Most of the nitrate reductase activity (80%;) in carob (Ceratonia siliqua L. cv. Mulata) is localised in the roots. The nitrate concentration in the leaves is relatively low compared to that in the roots, suggesting that nitrate influx into the leaf may be a major factor limiting the levels of nitrate reductase in the shoot. Transport of nitrate from root to shoot appears limited by the entrance of nitrate into the xylem. In order to study this problem, we determined the nitrate concentrations and nitrate reductase activities along the roots of nitrate-grown plants, as well as the composition of the xylem sap and the nitrate levels in the leaves. Some of the the bypocotyl, in order to bypass the loading of nitrate into the xylem of the roots. The results show that the loading of nitrate into the xylem is a limiting step. The cation and anion concentrations of nitrate- and ammonium-fed plants were similar, showing almost no production of organic anions. In both nitrate- and ammonium-fed plants, the transport of nitrogen from root to shoot was in the form of organic nitrogen compounds. The nitrate reductase activity in the roots was more than sufficient to explain all the efflux of OH− into the root medium of nitrate-fed plants. In carob plants the K-shuttle may thus be operative to a limited extent only, corresponding to between 11 and 27%; of the nitrate taken up. Potassium seems to be the cation accompanying stored nitrate in the roots of carob seedlings, since they accumulate nearly stoichiometric amounts of K+ and NO−3.
- Phenological and physiological studies during carob (Ceratonia siliqua L.) seed germinationPublication . Martins-Loução, M. A.; Duarte, P.J.; Cruz, C.The best pre-sowing treatments for carob (Ceratonia siliqua L.) seeds germination were acid scarification or treatment with warm water (40°C) for 48 h. Different phenological phases were characterized essentially based on morphological events during carob germination. Changes in total protein, free animo acid content and ethylene production were also studied and used for physiological characterization of phenological events. The fresh and dry weight of seedlings showed a steady increase, after the emergence of the radicle. At this point ethylene production attained the highest level. Dry weight of seedlings and cotyledons increase was accompanied by a decrease of endosperm reserves until they reached a plateau by the eighth day. Both protein and amino acid content of cotyledons increased with germination up to 6 days and then decreased. That increase was related to the onset of germination and hook development. It remained almost unchanged on subsequent days but between the 12th and the 14h the protein and amino acid content of cotyledons slowly started to increase. Embryonic axis amino acid content followed the same pattern but protein content only showed small variations throughout the experimental period. The presence of cotyledons as a source of necessary products for the development of the embryonic axis is discussed.
- The effect of nitrogen source on photosynthesis of carob at high CO2 concentrationsPublication . Cruz, C.; Lips, S. H.; Martins-Loução, M. A.Carob seedlings (Ceratonia siliqua L. cv. Mulata), fed with nitrate or ammonium, were grown in growth chambers containing two levels of CO2 (360 or 800 μl l−1), three root temperatures (15, 20 or 25°C), and the same shoot temperature (20/24°C, night/day temperature). The response of the plants to CO2 enrichment was affected by environmental factors such as the type of inorganic nitrogen in the medium and root temperature. Increasing root temperature enhanced photosynthesis rate more in the presence of nitrate than in the presence of ammonium. Differences in photosynthetic products were also observed between nitrate- and ammonium-fed carob seedlings. Nitrate-grown plants showed an enhanced content of sucrose, while ammonium led to enhanced storage of starch. Increase in root temperature caused an increase in dry mass of the plants of similar proportions in both nitrogen sources. The enhancement of the rates of photosynthesis by CO2 enrichment was proportionally much larger than the resulting increases in dry mass production when nitrate was the nitrogen source. Ammonium was the preferred nitrogen source for carob at both ambient and high CO2 concentrations. The level of photosynthesis of a plant is limited not only by atmospheric CO2 concentration but also by the nutritional and environmental conditions of the root.
- The strength of the biotic compartment to retain nitrogen additions prevents nitrogen losses from a Mediterranean maquisPublication . Dias, T.; Martins-Loução, M. A.; Sheppard, L.; Cruz, C.Nitrogen (N) is one of the nutrients most limiting to ecosystem productivity. However, N availability is increasing globally, which may affect ecosystem functions and stability. To understand the role of each ecosystem compartment in the cycling of increased N, we studied the initial response of a nutrient-poor ecosystem, a Mediterranean maquis, to increased N. N availability (dose and forms) was modified by three N additions along the year (spring, summer and middle autumn/winter). Soil inorganic N pools (nitrate in particular) strongly reflected the N additions in autumn, almost matching the total N added along the three additions. Cistus ladanifer, the dominant plant species, responded to the increased N (cover and N concentration in leaves and litter), and given that leaf shedding occurs in the summer, the importance of this N pool returning to the soil through litter decomposition on the total soil inorganic N in autumn was investigated. Data suggest that living plants and litter have a crucial role in preventing N losses from Mediterranean maquis. This is the first integrated field study on how European Mediterranean ecosystems retain increased N of different forms and doses, however longer-term studies are needed to explore the generality of this study’s observations.
- Uptake of ammonium and nitrate by carob (Ceratonia siliqua) as affected by root temperature and inhibitorsPublication . Cruz, C.; Lips, S. H.; Martins-Loução, M. A.Seedlings of carob (Ceratonia siliqua L. cv. Mulata) were grown in nutrient solution culture for 5 weeks, with or without nitrogen at different root temperatures (10, 16, 22, 30, 35 or 40deg;C) and with the air temperature kept between 20 and 24°C. The nitrogen was given as either ammonium or nitrate. At all root temperatures studied, nitrogen-depleted plants developed higher net uptake rates for nitrogen than plants grown in the presence of nitrogen. Temperature affected the kinetic parameters of nitrate uptake more than those of ammonium uptake. With increasing root temperature, the Km of ammonium uptake decreased, but to a lesser extent than the Km for nitrate. The increase in Vmax of ammonium uptake with temperature was also less noticeable than that for nitrate uptake. Ammonium and nitrate uptakes were inhibited in a similar way by respiratory or protein synthesis inhibitors. It may be noted that ammonium uptake in the presence of inhibitors at 40°C was higher than uptake at 10°C without inhibitors. Some similarities between the transport mechanisms for nitrate and ammonium are underlined in the present work. Components of both transport systems displayed saturation kinetics and depended on protein synthesis and energy. The following components of nitrate uptake were distinguished: (a) a passive net influx into the apparent free space; (b) a constitutive active uptake and (c) active uptake dependent on protein synthesis. We may similarly define three ammonium uptake systems: (a) a passive influx into the apparent free space; (b) passive diffusion uptake at high temperature and (c) active uptake dependent on protein synthesis. The possible role of the ratio between mechanism (c) and mechanism (b) as determinant of ammonium sensitivity is discussed.