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Biomedical subjects

J Magalhães

Publications and source records attributed to J Magalhães.

15 recordsLinked to original sources
PubMed2006

Hemostatic response to acute physical exercise in healthy adolescents.

The chronic and immediate post-exercise responses in the hemostatic and fibrinolytic systems have been shown to be variable and reflect differing adaptations with ageing and responses to exercise protocols. This study investigated the effects of acute and exhaustive exercise on the amplitude and duration of hemostatic and fibrinolytic responses in young adolescent males. The sample comprised 10 sedentary boys (13.2+/-0.5 years, 55.8+/-11.3kg, 165.7+/-7.4cm), who had not exercised or received any medication for at least 2 weeks before the experiments. The subjects performed exhaustive stepping exercise, consisting of 1s up and down cycles to fatigue. When the subjects were unable to maintain the required stepping rhythm, they were given a 30s recovery period. Following each 30s recovery participants recommenced the stepping cadence until fatigue prevented them continuing. Venous blood samples were drawn before and immediately, 1 and 24h after exercise to assess the following coagulation and fibrinolytic parameters: Platelet counts, activated partial thromboplastin time (aPTT), prothrombin time (PT), coagulation factor VIII (FVIII:C), von Willebrand factor (vWF), fibrinogen concentration, thrombin-antithrombin complex (TAT), D-dimer, plasminogen activator inhibitor (PAI-1), and tissue-type plasminogen activator (t-PA). Immediately following exercise, platelet counts, aPTT, FVIII, vWF and t-PA were significantly elevated in contrast to PAI-1, which decreased significantly until 1h after exercise. FVIII and platelet counts were elevated at 1 and 24h after exercise, respectively. Only the parameters FVIII and PAI-1 did not return to baseline values during the first hour after physical exercise. When compared to adults the results revealed different rates and ranges of coagulation and fibrinolysis parameters being activated by exhaustive exercise in this group of adolescents.

Adolescent↗
PubMed2006

Relationship between physical activity and obesity in children and adolescents.

AIM: The purpose of the present study was to analyze the relationship between physical activity (PA) and obesity in Portuguese children and adolescents. METHODS: The sample consisted of 1341 children and adolescents (8-15 years of age), 634 males (age, 10.6+/-2.3 y; body mass, 40.6+/-12.7 kg; height, 1.431+/-1.41 m) and 707 females (age, 10.9+/-2.4 y; body mass, 50+/-12.4 kg; height, 1.428+/-1.32 m). The sample was divided into quartiles of percentage of body fat (%BF) and physical activity index (PAI), within age and gender. Children in the upper %BF quartile were defined as obese (arbitrary definition). Logistic regression for each PAI quartile was used to determine the odds ratio of obese children and adolescents (> or = P75 of %BF) in comparison to their non-obese counterparts (< P75 of %BF). RESULTS: Males in the lowest PAI quartile have an odds ratio of 2.1 of having obesity in relation to males in the highest PAI quartile. For females any significant result was found between PAI quartiles. CONCLUSIONS: The results obtained in this study add some data to the controversy of PA and obesity relationship youth. Logistical regression shows that males who have a lower PAI have an odds ratio of 2.1 of obesity, in comparison with males that have higher PAI. Those findings were not found in girls.

Adolescent↗
PubMed2005

PAX8-PPARgamma rearrangement is frequently detected in the follicular variant of papillary thyroid carcinoma.

CONTEXT: The clinicopathological characteristics and the molecular features of the follicular variant of papillary thyroid carcinoma (FVPTC) remain controversial. OBJECTIVE/DESIGN/PATIENTS: In an attempt to clarify such controversies and to find whether or not FVPTC cases share the molecular features of follicular tumors, we searched for the presence of PAX8-PPARgamma rearrangements, RAS mutations, and RAP-1, RAF-1, and BRAF mutations in a series of 40 FVPTCs as well as in 27 follicular thyroid carcinomas (FTCs) and 12 follicular thyroid adenomas (FTAs). Fluorescence in situ hybridization and RT-PCR were used to detect the PAX8-PPARgamma rearrangement and PCR, single strand confirmational polymorphism, and sequencing for searching the mutations. RESULTS: The frequency of PAX8-PPARgamma rearrangement was similar in FVPTCs (37.5%), FTCs (45.5%), and FTAs (33.3%). The same holds true regarding the frequency and type of RAS mutations: FVPTC, 25.0%; FTC, 22.2%; and FTA, 33.3%. BRAF mutations were only detected in FVPTC (10%); the BRAF mutations in these cases (K601E and G474R) are different from the typical BRAF(V600E) mutation of conventional PTCs. No mutations were detected in RAP-1 and RAF-1. In FVPTCs, the PAX8-PPARgamma rearrangement was significantly associated with multifocality and vascular invasion, whereas the RAS mutations were significantly associated with the large tumor size. There were three cases of FVPTC, three FTCs and one FTA, harboring both PAX8-PPARgamma rearrangement and RAS mutations; patients with such tumors were usually very young. CONCLUSIONS: We conclude that a subset of FVPTC shares some of the molecular features of follicular tumors. Further studies are necessary to clarify the putative clinical significance (e.g. association to blood-born metastases) of PAX8-PPARgamma rearrangement, RAS mutations, and BRAF(K601E) in FVPTCs.

Adult↗
PubMed2005

Acute and chronic exposition of mice to severe hypoxia: the role of acclimatization against skeletal muscle oxidative stress.

The role of acclimatization and the effect of persistent severe hypoxia (7000 m) were analyzed in mice soleus muscle with respect to oxidative stress (glutathione redox status) and damage markers (TBARS and SH protein groups), NAG and SOD activities and HSP70 expression. Forty mice were divided into one normobaric-normoxic control group and four hypobaric-hypoxic experimental groups (n = 8). One experimental group (1 D) was acutely exposed to a simulated altitude of 7000 m in a hypobaric chamber for 1 day. Another experimental group (ACCL + 1 D) was exposed to a 3 days acclimatization period plus 1 day of hypoxia exposure at 7000 m. The third experimental group (ACCL + 8 D) was exposed to the same acclimatization protocol, remaining 8 subsequent days at 7000 m. The fourth experimental group (8 D) was chronically exposed without acclimatization. ACCL + 1 D showed a significant decrease (p < 0.05) in oxidative stress and damage compared to the 1 D group. Concerning chronic severe hypoxia, acclimatization was truly vital, since 8 D animals died after 5 days of exposure. Oxidative stress and damage markers in ACCL + 8 D tended to gradually increase throughout the 8 days of the hypoxic period. Total SOD activity did not change in 1 D compared to control; however, it increased significantly (p < 0.05) in ACCL + 1 D and ACCL + 8 D. HSP70 expression followed the observed oxidative stress and damage pattern, suggesting a protective role against hypoxia-induced oxidative stress. The present study supports the hypothesis that acclimatization attenuates oxidative stress and damage induced by acute hypoxia, although a trend to a gradually increased oxidative deleterious effect in skeletal muscle seems to occur during persistent severe hypoxia even after a previous acclimatization period.

Adaptation, Physiological↗
PubMed2004

D-amphetamine-induced hydrogen peroxide production in skeletal muscle is modulated by monoamine oxidase inhibition.

The aim of this paper was to study the influence of d-amphetamine administration as a sympathomimetic drug on the synthesis of hydrogen peroxide (H2O2) in mouse soleus muscle and to investigate the modulating effects of pargyline, an inhibitor of monoamine oxidase (MAO) in this context. Charles River mice were assigned to four groups: Control, d-amphetamine treated, pargyline treated, and amphetamine + pargyline treated. Their soleus muscles were removed 0, 15, 30, 60, and 120 min after treatment. The amount of hydrogen peroxide formation within the muscles was estimated using an indirect method. The control data showed a continuous production of hydrogen peroxidase. Pargyline administration lead to an initial increase of H2O2 production that later faded below control levels. Administration of amphetamine finally stimulated H2O2 production much above control levels. When combining amphetamine and pargyline treatment, H2O2 production was accelerated in the initial phase but dropped to control levels at 30 min. It is concluded that in skeletal muscle MAO is an important source of hydrogen peroxide production triggered by amphetamine administration and that this tissue plays a hitherto not described role in oxidizing circulating biogenic monoamines.

Animals↗
PubMed2004

Concentric quadriceps and hamstrings isokinetic strength in volleyball and soccer players.

AIM: Muscular strength is one of the most important components of sport, both for high performance and for injury prevention. One of the most used methods to assess strength muscle balance between dominant (D)/non-dominant (ND) and antagonist/agonist is isokinetic testing. The main purpose of the present study was to describe and to compare isokinetic strength profiles (peak torque, bilateral strength differences between D/ND leg (BD) and hamstrings/quadriceps (H/Q) ratio) in athletes of different sports and positional roles. METHODS: Twenty-eight elite volleyball players and 47 pro soccer players (goalkeepers, n = 5; full-backs, n = 7; defenders, n = 10; midfielders, n = 15; forwards, n = 10) were evaluated using an isokinetic dynamometer (Biodex-System 2). Maximal gravity corrected concentric peak torque of knee extensor and flexor muscles were measured at angular velocities of 360 degrees x s(-1) (6.28 rad x s(-1)) and 90 degrees x s(-1) (1.57 rad x s(-1)). RESULTS: No significant BD were found between soccer and volleyball players with exception of hamstrings at 90 degrees x s(-1) (soccer: 10.6 +/- 8.0% vs volleyball: 6.9 +/- 5.5%). The H/Q ratio was significantly lower in volleyball players at 90 degrees x s(-1) (D: soccer 57.4 +/- 6.7% vs volleyball 50.4 +/- 7.2%; ND: soccer: 56.1 +/- 8.2% vs volleyball: 50.5 +/- 6.4%). No significant differences were found for BD and H/Q ratio in soccer players of different positional roles. CONCLUSION: In general, soccer and volleyball players do not seem to be different concerning BD although a significant difference was observed in hamstrings at 90 degrees x s(-1). Moreover, our data suggest that specific demands of these sports and the different positional roles in soccer did not induce bilateral leg imbalances. However, sport demands seem to influence isokinetic concentric H/Q ratio.

Adult↗
PubMed1984

Sodium taurocholate effect on beta-glucosidase activity: a new approach for identification of Gaucher disease using the synthetic substrate and leucocytes.

In this work we have studied the leucocytes and sera of 3 Gaucher patients, 4 obligate heterozygotes, 11 brothers and sisters of patients and 11 controls. Beta-glucosidase activity with 4-M-U-beta-glucopyranoside has been assayed at different pH's, in the presence of pure sodium taurocholate. At pH 4.5 and 5.0 sodium taurocholate activates the beta-glucosidase of control leucocytes, but inhibits the residual enzyme present in Gaucher leucocytes. The ratio of beta-glucosidase activity in the presence and absence of this effector seems to be a good approach to the diagnosis of Gaucher disease and it has proved indispensible in one patient's diagnosis. The apparent Km of beta-glucosidase determined for the same substrate, at pH 4.5 and 5.5 in the presence of sodium taurocholate showed markedly lower values in the patients than in the controls. An increased serum acid phosphatase activity, previously described as a secondary alteration in Gaucher disease, has also been studied and seems to be a useful complementary test, particularly when its age dependence is taken into account.

Acid Phosphatase↗
PubMedDate not supplied

[Study of some physical and biological properties of an endodontic sealer composed of calcium hydroxide].

The authors present a study of the physical and biological properties of a new endodontic cement known as Sealapex. In its composition the presence of calcium hydroxide is introduced in order to induce calcification of the periapical tissue. Our results using glass round cover slips implanted on the subcutaneous tissue of mice indicated a persistent foreign body reaction (60 days). The physical properties studied compared to N-Rickert ciment indicated, a decreased leakage. Adhesivity tests didn't give us significant values. Laboratorial studies and clinical trials are necessary to a complete acceptance of this new ciment in endodontic treatment.

Animals↗
PubMedDate not supplied

[Evaluation of the histocompatibility of endodontic cement in subcutaneous connective tissue using three methods].

It was employed three methods to evaluate the histocompatibility of a root canal filling cement, as the N-Rickert paste: implantation of round glass cover slips, polyethylene tubes and pellets of the cement. The results demonstrated qualitative and quantitative differences among the methods utilized indicating as a good toll the use of glass cover slips covered by the cement, since they provide good conditions of work, major areas of study, as also facilities in obtaining the specimens for study. The pellets didn't simulate the clinical conditions of the cement and the very small areas of study of the polyethylene tubes don't give definitive conclusions.

Animals↗
PubMedDate not supplied

[Applications of problem-based learning in the basic medical curriculum].

This article describes a project, which took place between 1992 and 1994, on the application of problem-based learning to three disciplines of the basic medical curriculum: Biochemistry (1st year) Physiology (2nd year) and physiopathology (3rd year). The main objectives of the project were to bring teaching closer to the future professional reality, to stimulate critical thinking and to facilitate independent learning. Despite differences in content and in teaching materials, the trigger event for learning was information given within a clinical context which was further analyzed in small-group tutorial sessions. The project also included the training of the tutors and the development of audiovisual materials. Although no statistically significant differences were found in the final scores between students taught during this period and before, the first group reported a considerable increase in the motivation to learn which, in the case of Biochemistry, was important to change the passive attitude of most students on entering university. The project also helped to create the appropriate atmosphere for the establishment of an office for medical education in the medical school to support other innovations in the field. With this project we wished to contribute, with a concrete experience, to the reform of medical education in Portugal, by demonstrating that problem-based learning can be used in single disciplines without major changes in the basic curriculum.

Curriculum↗