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Biomedical subjects

A R Oliveira

Publications and source records attributed to A R Oliveira.

17 recordsLinked to original sources
PubMed2006

Estimation of the lactate threshold from heart rate response to submaximal exercise: the pulse deficit.

In this study, we evaluated the validity of a sharp increase in pulse deficit (PD) as a noninvasive index for estimation of the first lactate threshold (LT (1)) in healthy individuals with various levels of aerobic fitness. Three groups of healthy male subjects participated in the study: 15 sedentary individuals, 14 students of physical education, and 13 competitive athletes. Each subject performed a maximal incremental exercise test on the cycle ergometer for the determination of the LT (1), the second lactate threshold, and peak power output. On different days, subjects performed several 8-min bouts of constant-load exercise on the cycle ergometer, corresponding to each of the power outputs of the maximal test, to evaluate PD, which was calculated as the total number of heart beats of the last 4 min minus the total number of heart beats in the first 4 min of exercise. The three groups presented similar blood lactate, heart rate and pulse deficit responses to exercise. For the first power output up to the LT (1), PD showed no significant changes. For the three groups, a sharp increase in PD was seen at the intensity immediately above LT (1). There was a significant correlation between PD and blood lactate changes from the rest to 4th min of submaximal exercise (r = 0.83, p < 0.05). The power output before a sharp increase in PD detected during constant-load exercise (112 +/- 38 W) and the power output corresponding to the LT (1) detected during the incremental test (111 +/- 37 W, p = 0.323) were similar and strongly correlated (r = 0.99, p = 0.0001). The absolute cut-point value of 25 beats for PD had a sensitivity of 100 %, a specificity of 95 %, and a positive predictive value of 90 % for the detection of LT (1). The determination of PD provides an accurate noninvasive estimate of the LT (1) in healthy young men with different levels of fitness. One 8-min submaximal exercise bout can establish if an individual is exercising above or below the LT (1).

Adult↗
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

Exhaustive exercise with high eccentric components induces prothrombotic and hypofibrinolytic responses in boys.

It is known that coagulation and fibrinolysis are activated after exercise, and that the response is related to exercise intensity. The contribution, however, of eccentric exercise has not yet been investigated. Twenty boys (age 13 years) were randomly assigned to two experimental groups, which had to perform a monopedal stepping exercise until exhaustion. One group had to step up and down (U/D) in the same rhythm of one second each, while the other group (U/DD) had to step up during one second and to step down during two seconds, thereby experiencing a higher eccentric load. Blood samples were collected before and at 0, 1, and 24 hrs after exercise, and F VIII, t-PA, PAI-1, and D-dimer were determined as markers for coagulation or fibrinolysis, respectively. While the tendency for hypercoagulability was counterbalanced by fibrinolysis in the U/D group, the U/DD group showed a prothrombotic and hypofibrinolytic hemostatic response. It is assumed that eccentric exercise, beyond the well-known muscle fiber damage, also leads to some damage of the endothelial cells, affecting their capacity to liberate sufficient amounts of fibrinolytic agents.

Adolescent↗
PubMed2003

Comparative analyses of the complete genome sequences of Pierce's disease and citrus variegated chlorosis strains of Xylella fastidiosa.

Xylella fastidiosa is a xylem-dwelling, insect-transmitted, gamma-proteobacterium that causes diseases in many plants, including grapevine, citrus, periwinkle, almond, oleander, and coffee. X. fastidiosa has an unusually broad host range, has an extensive geographical distribution throughout the American continent, and induces diverse disease phenotypes. Previous molecular analyses indicated three distinct groups of X. fastidiosa isolates that were expected to be genetically divergent. Here we report the genome sequence of X. fastidiosa (Temecula strain), isolated from a naturally infected grapevine with Pierce's disease (PD) in a wine-grape-growing region of California. Comparative analyses with a previously sequenced X. fastidiosa strain responsible for citrus variegated chlorosis (CVC) revealed that 98% of the PD X. fastidiosa Temecula genes are shared with the CVC X. fastidiosa strain 9a5c genes. Furthermore, the average amino acid identity of the open reading frames in the strains is 95.7%. Genomic differences are limited to phage-associated chromosomal rearrangements and deletions that also account for the strain-specific genes present in each genome. Genomic islands, one in each genome, were identified, and their presence in other X. fastidiosa strains was analyzed. We conclude that these two organisms have identical metabolic functions and are likely to use a common set of genes in plant colonization and pathogenesis, permitting convergence of functional genomic strategies.

Base Sequence↗
PubMed2000

Effects of exercise training on autonomic and myocardial dysfunction in streptozotocin-diabetic rats.

Several investigators have demonstrated that diabetes is associated with autonomic and myocardial dysfunction. Exercise training is an efficient non-pharmacological treatment for cardiac and metabolic diseases. The aim of the present study was to investigate the effects of exercise training on hemodynamic and autonomic diabetic dysfunction. After 1 week of diabetes induction (streptozotocin, 50 mg/kg, iv), male Wistar rats (222 +/- 5 g, N = 18) were submitted to exercise training for 10 weeks on a treadmill. Arterial pressure signals were obtained and processed with a data acquisition system. Autonomic function and intrinsic heart rate were studied by injecting methylatropine and propranolol. Left ventricular function was assessed in hearts perfused in vitro by the Langendorff technique. Diabetes (D) bradycardia and hypotension (D: 279 +/- 9 bpm and 91 +/- 4 mmHg vs 315 +/- 11 bpm and 111 +/- 4 mmHg in controls, C) were attenuated by training (TD: 305 +/- 7 bpm and 100 +/- 4 mmHg). Vagal tonus was decreased in the diabetic groups and sympathetic tonus was similar in all animals. Intrinsic heart rate was lower in D (284 +/- 11 bpm) compared to C and TD (390 +/- 8 and 342 +/- 14 bpm, respectively). Peak systolic pressure developed at different pressures was similar for all groups, but +dP/dt max was decreased and -dP/dt max was increased in D. In conclusion, exercise training reversed hypotension and bradycardia and improved myocardial function in diabetic rats. These changes represent an adaptive response to the demands of training, supporting a positive role of physical activity in the management of diabetes.

Animals↗
PubMed1997

Exercise training in aging: hemodynamic, metabolic, and oxidative stress evaluations.

The effects of exercise training on hemodynamic and metabolic parameters as well as on responses to oxidative stress in aged individuals are controversial. The aim of the present study was to investigate changes in heart hate, mean arterial pressure, vasoreactivity, and plasma levels of insulin and glucose in male aged Wistar rats submitted to exercise training for 11 weeks (1 h/d; 5 d/wk) in a treadmill. The isolated heart was perfused by H2O2, and oxidative stress was evaluated using thiobarbituric acid reactive substances. Cardiovascular functions were recorded with a data acquisition system (CODAS, 1 kHz). Trained aged rats were bradycardic as compared with sedentary aged rats (298+/-7 versus 336+/-16 bpm) but presented similar mean arterial pressure and vasoreactivity and plasma levels of insulin and of glucose, which were quantified by radioimmunoassay and colorimetric enzymatic test. Plasma levels of insulin and of glucose ratio were increased in trained aged rats (6.9+/-0.7 versus 3.5+/-0.4 in sedentary aged rats), and the response to oxidative stress was decreased (0.4+/-0.1 versus 0.7+/-0.1 nmol/mg protein in sedentary aged rats). These results showed that exercise training produced a lower resting heart rate as well as changes in metabolic and oxidative responses. This suggests a higher myocardium protection of trained than sedentary aged rats.

Aging↗
PubMed1997

Effect of trolox C on cardiac contracture induced by hydrogen peroxide.

Hydrogen peroxide (H2O2) perfused into the aorta of the isolated rat heart induces a positive inotropic effect, with cardiac arrhythmia such as extrasystolic potentiation or cardiac contractures, depending on the dose. The last effect is similar to the "stone heart" observed in reperfusion injury and may be ascribed to lipoperoxidation (LPO) of the membrane lipids, to protein damage, to reduction of the ATP level, to enzymatic alterations and to cardioactive compounds liberated by LPO. These effects may result in calcium overload of the cardiac fibers and contracture ("stone heart"). Hearts from male Wistar rats (300-350 g) were perfused at 31 degrees C with Tyrode, 0.2 mM trolox C, 256 mM H2O2 or trolox C + H2O2. Cardiac contractures (baseline elevation of the myograms obtained) were observed when hearts were perfused with H2O2 (Tyrode: 5.9 +/- 3.2; H2O2: 60.5 +/- 13.9% of the initial value); perfusion with H2O2 increased the LPO of rat heart homogenates measured by chemiluminescence (Tyrode: 3,199 +/- 259; H2O2: 5,304 +/- 133 cps mg protein-1 60 min-1), oxygen uptake (Tyrode: 0.44 +/- 0.1; H2O2: 3.2 +/- 0.8 nmol min-1 mg protein-1) and malonaldehyde (TBARS) formation (Tyrode: 0.12 +/- 0; H2O2: 0.37 +/- 0.1 nmol/ml). Previous perfusion with 0.2 mM trolox C reduced the LPO (chemiluminescence: 4,098 +/- 531), oxygen uptake (0.51 +/- 0) and TBARS (0.13 +/- 0) but did not prevent the H2O2-induced contractures (33.3 +/- 16%). ATP (Tyrode: 2.84 +/- 0; H2O2: 0.57 +/- 0) and glycogen levels (Tyrode: 0.46 +/- 0; H2O2: 0.26 +/- 0) were reduced by H2O2. Trolox did not prevent these effects (ATP: 0.84 +/- 0 and glycogen: 0.27 +/- 0). Trolox C is known to be more effective than alpha-tocopherol or gamma-tocopherol in reducing LPO though it lacks the phytol portion of vitamin E to be fixed to the cell membranes. Trolox C, unlike vitamin A, did not prevent the glycogen reduction induced by H2O2. Trolox C induced a positive chronotropic effect that resulted in higher energy consumption. The reduction of energy level seemed to be more important than LPO in the mechanism of H2O2-induced contracture.

Animals↗
PubMed1995

Changes in blood pressure control in aged rats.

The aging process is related to several changes in cardiovascular, metabolic and autonomic functions. However, descriptions of changes in arterial pressure (AP), baroreflex sensitivity and associated variations of serum glucose and insulin are controversial. The aim of this paper was to study AP, baroreflex sensitivity and changes in plasma levels of glucose and insulin of young (10 weeks, 239 +/- 4.3 g) and aged (18-24 months, 412 +/- 8.5 g) male Wistar rats. AP pulses were videotaped and processed on a microcomputer, using an analog-to-digital converter (beat-to-beat analysis). Baroreflex sensitivity was evaluated measuring heart rate changes induced by mean arterial pressure (MAP) variations produced by phenylephrine and sodium nitroprusside injections (N = 10 in each group). Plasma glucose (N = 10 in each group) and plasma insulin (N = 6 in each group) were quantified by a colorimetric enzymatic test and radioimmunoassay, respectively. There were no differences in systolic, diastolic or mean AP (110 +/- 5 vs 107 +/- 3 mmHg) between aged and young rats. The tachycardic response to the reduction of AP was impaired in aged compared to young rats (-1.95 +/- 0.29 vs -3.26 +/- 0.49 bpm/mmHg), while the bradycardic response to increases in AP was similar (-1.02 +/- 0.22 vs -1.5 +/- 0.26 bpm/mmHg). Basal levels of glucose (83 +/- 6 vs 62 +/- 4 mg/dl) and insulin (8.3 +/- 2 vs 4 +/- 0.5 microU/ml) were different. Thus, the reflex tachycardia evoked by a fall in AP is depressed in old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

Comparative characterization of a human large cell lung carcinoma cell line and the xenograft derived cell line.

The HK-1 cell line established from a human large cell lung carcinoma shows a high transformed phenotype and undifferentiated characteristics. This cell line grows as an adherent monolayer in fetal calf serum-supplemented medium, shows a high proliferation index, is able to grow in semi-solid agar and is tumorigenic in athymic nude rats. The cell line HK-2 derived from the HK-1 xenograft in athymic nude rats shows basically the same features found in the original HK-1 cell line, which include aneuploid nuclear DNA content, abnormal chromosomal number. rearranged marker chromosomes and abnormally localised nucleolar organizer regions. Cytokeratin and vimentin intermediary-sized filaments were found in both cell lines as well as in the original and induced tumour, while neither oncofetal antigens (alphafeto-protein, carcinoembryonic antigen, chorionic gonatropin and human placental lactogen) nor neural differentiation markers (neurofilament and neural specific enolase) were expressed. Analysis of sulphated glycosaminoglycans in the cell cultures and in the nude rat induced tumour showed high expression of chondroitin sulphate.

Animals↗
PubMed1991

Medical and related aspects of the Goiânia accident: an overview.

On 13 September 1987, a radiation accident occurred in the city of Goiânia in Central Brazil. Approximately 250 people were exposed to a 137Cs source from an abandoned radiotherapy unit. At least 14 patients showed some degree of bone marrow depression, and eight developed the classical signs and symptoms of acute radiation syndrome (ARS). Twenty-eight people presented local radiation injuries ranging from first to third degree, and 104 individuals showed evidence of internal contamination. This paper describes the circumstances of the event, the first-aid measures taken, the criteria adopted for triage of the exposed population, and the radiation protection procedures used during the clinical management of the irradiated individuals.

Accidents↗
PubMed1991

Localized lesions induced by 137Cs during the Goiânia accident.

A description is given of initial symptoms and clinical observations regarding acute localized radiation lesions in 28 persons exposed to 137Cs during the Goiânia radiological accident. Specialized procedures to estimate the extent and gravity of the lesions and establish a therapeutic strategy, as well as to anticipate the prognosis in each case, are briefly discussed. Measures taken for reduction of pain and inflammation are noted, and an explanation is given for difficulties encountered due to adverse working conditions and the serious clinical manifestations presented by various patients concomitantly with their lesions. Also noted is the difficulty in obtaining credible information regarding exposure, such as source-to-object distance, duration of exposure, and source activity, which precluded dosimetry studies in most cases.

Accidents↗
PubMed1991

Medical aspects of 137Cs decorporation: the Goiânia radiological accident.

In September 1987, the Goiânia radiological accident involving a source of 137Cs culminated in about 140 victims who presented internal and/or external contamination and/or external exposure to radiation and/or radiation burns. Internal contamination was verified through analysis of urine and fecal samples. Internal contamination was also evaluated by measurements performed at the whole-body counter installed in Goiânia in November 1987. To enhance the decorporation of 137Cs, patients were treated with the following: 1) Prussian Blue, oral administration, in 46 patients; 2) diuretics, oral administration, in 17 patients; 3) induced perspiration, increasing 137Cs elimination. These procedures were done under rigorous clinical evaluation and considering the data from assay of excreta and data obtained from the whole-body counter. The doses of Prussian Blue exceeded about 6.5 times the dose previously indicated in the literature. It was the first time diuretics were used in humans to treat 137Cs internal contamination. The results of these procedures are discussed.

Accidents↗
PubMed1991

Clinical and hematological aspects of 137Cs: the Goiânia radiation accident.

Fifty persons involved in the 137Cs accident in Goiânia showed symptoms of whole-body and local acute irradiation and also external or internal contamination mainly due to ingestion or absorption of 137Cs. Fourteen of the 50 developed severe bone marrow depression characterized by neutropenia and thrombocytopenia. Eight of these 14 received GM-CSF intravenously. None were submitted to bone marrow transplantation. Four of the 14 died due to hemorrhage and infection. For those with significant internal contamination evaluated by in-vitro and in-vivo assays, Prussian Blue was administered with doses ranging from 1.5 to 10 g d-1. Besides Prussian Blue, other measures were taken to increase decorporation of 137Cs, including administration of diuretics, water overload, and ergometric exercises. From 50 to 100 persons are being followed in a medical protocol.

Accidents↗
PubMed1983

Detection of snail hemocyanin in the whole hemolymph by serologically specific electron microscopy.

This study demonstrates the applicability of the serologically specific electron microscopy (SSEM) technique in the detection of hemocyanin molecules in the whole hemolymph of the snail, Megalobulimulus ovatus. The results are positive and easily reproducible. The SSEM might be useful as a technique for taxonomic studies of snails as well as to study structural aspects of their hemocyanin molecules.

Animals↗
PubMedDate not supplied

[Accidental exposure to X-ray from a diffractometer].

The patients's clinical pictures, characterized by an erythema preceding the skin manifestations, their aspect and the occupational histories, made the diagnosis of a radiation accident possible before its dosimetric identification. Doses evaluations using thermoluminescence dosimeters and ionizing chambers correlated well with the clinical estimations. The immediate cause of the accident was poor maintenance of the device that caused its back window to be permanently open, but lack of adequate information on the biological effects of ionizing radiation and on the correct operational procedures were contributory facts. The description of this accident is relevant in virtue of the misconception that such equipment have "virtually no occupational risk". The patients's medical evolutions have had a favorable course, specially because the low energy of the X-ray and its low penetrating capacity. This accident highlights the need for the adequate training of workers on the handling of radiation devices.

Acute Disease↗