Biomedical subjects

G Lopes

Publications and source records attributed to G Lopes.

At least 19 recordsLinked to original sources

PubMed2006

Undergraduate nursing students' perceptions of substance use and misuse: a Brazilian position.

Alcohol, cocaine and cannabis are the substances most commonly abused in Brazil. There is limited evidence on the perceptions of undergraduate nursing students towards substance misuse. Negative attitudes, in combination with the lack of appropriate knowledge and skills, may result in minimal care provided to substance misusers. The aims of the study are to examine the knowledge and attitudes of undergraduate nursing students towards substance misusers and consider the implications of these attitudes for nursing education. The Nurse Education in Alcohol and Drug Educational Faculty Survey (NEADA) questionnaire on knowledge and education, nursing interventions, attitudes and values was distributed to undergraduate nurses (n = 227) in the south and south-eastern part of Brazil. The findings showed that there is a lack of adequate education in drug and alcohol use and misuse, including competency skills, but the participants were positive about treatment interventions. A paradigm shift in nurse education curricula and further research studies on attitudes and values towards substance misuse should be on the educational agenda. These are challenges faced by nurses to meet the healthcare needs of substance misusers.

Adult↗

PubMed2006

Teaching bovine rectal palpation with live cows in the slaughterhouse: is it worthwhile?

Bovine rectal palpation, a procedure that requires considerable practice to develop the necessary skills, is often taught during extramural activities, or even learnt in practice after graduation. However, student access to cows in extramural activities may be limited because of student numbers, animal welfare considerations and concerns over induction of embryo mortality because of inexperience of the student. To overcome some of these limitations, in our school practical classes of bovine rectal palpation are taught in a slaughterhouse, with small groups of approximately 10 students per class, over a period of 30 weeks. Number of cows palpated, type of cases found and the success rate of students in the final practical exam were recorded and analysed for 3 years, and contrasted with the pre-established goals for the course. Additionally, a questionnaire was sent to former students to assess their opinion on the usefulness of the palpation course, as well as to identify main learning difficulties and collect suggestions to improve teaching methods. Overall, the information obtained indicated that the course is useful to teach palpation skills, even if the original goals may have been very optimistic. Most (96%) of the respondents had the opinion that the course was very useful or useful. Several suggestions were offered to improve teaching methods, but there was no consensus on a single recommendation. Despite the fact that a considerable number of respondents to the questionnaire did not use bovine rectal palpation in their practice, only one considered the classes 'not useful'. It is concluded that this method of teaching rectal palpation should be continued and the teaching methods improved with the adoption of some modifications.

Abattoirs↗

PubMed2004

Anosmia following superior turbinate resection.

Nasal polyposis is a chronic inflammatory disease of the sinus mucosa responsible for, among other symptoms, alteration of the sense of smell in a considerable percentage of patients. One of the aims of surgical treatment is the recuperation of the sense of smell, especially in patients with good preoperative indicators suggesting a possible favorable outcome. The purposes of this brief clinical report are to present the case of a patient with nasal polyposis who developed anosmia after a bilateral endoscopic functional ethmoidectomy with inadvertent resection of both superior turbinates, and to discuss briefly the possible physiopathological mechanisms that could explain it.

Adult↗

PubMed2003

L- and DL-carnitine induce tetanic fade in rat neuromuscular preparation.

Carnitine, a structurally choline-like metabolite, has been used to increase athletic performance, although its effects on neuromuscular transmission have not been investigated. It is present in skeletal muscle and its plasma levels are about 30 to 90 micro M. Using rat phrenic nerve diaphragm preparations indirectly and directly stimulated with high rate pulses, D-carnitine (30 and 60 micro M), L-carnitine (60 micro M) and DL-carnitine (60 micro M) were shown to induce tetanic fade (D-carnitine = 19.7 +/- 3.1%, N = 6; L-carnitine = 16.6 +/- 2.4%, N = 6; DL-carnitine = 14.9 +/- 2.1%, N = 6) without any reduction of maximal tetanic tension. D-carnitine induced tetanic fade in neuromuscular preparations previously paralyzed with d-tubocurarine and directly stimulated. The effect was greater than that obtained by indirect muscle stimulation. Furthermore, previous addition of atropine (20 to 80 micro M) to the bath did not reduce carnitine isomer-induced tetanic fade. In contrast to D-carnitine, the tetanic fade induced by L- and DL-carnitine was antagonized by choline (60 micro M). The combined effect of carnitine isomers and hemicholinium-3 (0.01 nM) was similar to the effect of hemicholinium-3 alone. The data suggest that L- and DL-carnitine-induced tetanic fade seems to depend on their transport into the motor nerve terminal.

Animals↗

PubMed2001

Spatial reconstruction of the human motion based on images of a single camera.

The inverse dynamic analysis procedures used in the study of the human gait require that the kinematics of the supporting biomechanical model is known beforehand. The first step to obtain the kinematic data is the reconstruction of human spatial motion, i.e., the evaluation of the anatomic points positions that enables to uniquely define the position of all anatomical segments. In photogrammetry, the projection of each anatomical point is described by two linear equations relating its three spatial coordinates with the two coordinates of the projected point. The need for the image of two cameras arises from the fact that three equations are necessary to find the original spatial position of the anatomical point. It is shown here that the kinematic constraint equations associated with a biomechanical model can be used as the extra set of equations required for the reconstruction process, instead of the equations associated with the second camera. With this methodology, the system of equations arising from the point projections and biomechanical model kinematic constraints are solved simultaneously. Since the system of equations has multiple solutions for each image, a strategy based on the minimization of the cost function associated to the smoothness of the reconstructed motion is devised, leading to an automated computer procedure enabling a unique reconstruction.

Biomechanical Phenomena↗

PubMed2001

Spatial reconstruction of human motion by means of a single camera and a biomechanical model.

The value of the results of the inverse dynamic analysis procedures used in the study of human tasks is dependent on the quality of the kinematic and kinetic data supplied to the biomechanical model that supports it. The kinematic data, containing the position, velocity and acceleration of all anatomical segments of the biomechanical model, result from the reconstruction of human spatial motion by means of the evaluation of the anatomic points positions that enable to uniquely define the position of all anatomical segments. Furthermore, the motion data must be kinematically consistent with the structure of the biomechanical model used in the analysis. The traditional photogrammetric methodologies used for the spatial reconstruction of the human motion require images of two or more calibrated and synchronized cameras. This is due to the fact that the projection of each anatomical point is described by two linear equations relating its three spatial coordinates with the two coordinates of the projected point. The need for the image of another camera arises from the fact that a third equation is necessary to find the original spatial position of the anatomical point. The methodology proposed here substitutes the projection equations of the second camera with the kinematic constraint equations associated with a biomechanical model in the motion reconstruction process. In the formulation the system of equations arising from the point projections and biomechanical model kinematic constraints, representing the constant length of the anatomical segments, are solved simultaneously. Because the system of equations has multiple solutions for each image, a strategy based on the minimization of a cost function associated to the smoothness of the reconstructed motion is devised. It is shown how the process is implemented computationally avoiding any operator intervention during the motion reconstruction for a given time period. This leads to an automated computer procedure that ensures the uniqueness of the reconstructed motion. The result of the reconstruction process is a set of data that is kinematically consistent with the biomechanical model used. Through applications of the proposed methodology to several sports exercises its benefits and shortcomings are discussed.

Biomechanical Phenomena↗

PubMed2001

Primary non-Hodgkin's lymphomas of the liver with nodular and diffuse infiltration patterns have different prognoses.

BACKGROUND: Primary liver non-Hodgkin's lymphomas have peculiar clinical and biological patterns. This study correlates these patterns with pathology and outcome. PATIENTS AND METHODS: Clinical records and histology of patients with primary liver non-Hodgkin's lymphoma, treated at our institution over a 20-year period, were reviewed. Lymphoproliferations occurring after liver transplantation were excluded. Survival analyses were performed with patients from the other published series (62 patients). RESULTS: Our series included eight patients. Three patients had a nodular liver infiltration, corresponding to a large B-cell lymphoma. Five patients had a diffuse liver infiltration, of whom three had a T-cell lymphoma with predominant sinusoid infiltration, and two had a large B-cell lymphoma. Patients with diffuse liver infiltration presented with hepatomegaly, and two of these also had acute liver failure. Diffuse infiltration had a worse prognosis than nodular infiltration (P = 0.0033). Among these latter patients, those treated with an anthracycline-based chemotherapy had a better outcome (P < 0.0001). CONCLUSIONS: Patients with primary liver lymphomas can be classified in two groups, depending on the type of infiltration. Those with nodular infiltration may benefit from anthracycline-based chemotherapy. Diffuse infiltration has a bad prognosis, and should be suspected in patients presenting with altered liver functions and hepatomegaly.

Adult↗

PubMed2001

Comparative effects of diet supplementation with l-carnitine and dl-carnitine on ammonia toxicity and hepatic metabolism in rats.

AIM: To compare the effects of chronic supplementation with l-carnitine (LCT) and dl-carnitine (DLC) on ammonia toxicity and hepatic metabolism. METHODS: Three groups of male adult rats were studied: 1) supplemented with LCT (1.2 mmol . kg-1 . d-1), 2) supplemented with DLC (1.2 mmol . kg-1. d-1), and 3) control group (COG) not supplemented. RESULTS: The treatment with LCT decreased the toxicity to ammonia. However, the supplementation with DLC did not show any significant effect. In contrast, the effects of the supplementation with LCT and DLC on hepatic metabolism were quite similar, ie, both groups showed: (a) intensified ammonia uptake and decreased urea production from ammonia; (b) increased glucose and urea production from L-glutamine (5 mmol/L). CONCLUSION: The results suggested that LCT supplementation might protect against ammonia toxicity by extra-hepatic mechanisms.

Acetates↗

PubMed2000

Time sequence of changes in the responsiveness of glycogen breakdown to adrenergic agonists in perfused liver of rats with insulin-induced hypoglycemia.

The time-course changes of the responsiveness of glycogen breakdown to alpha- and ss-adrenergic agonists during insulin-induced hypoglycemia (IIH) were investigated. Blood glucose levels were decreased prior to the alteration in the hepatic responsiveness to adrenergic agonists. The activation of hepatic glucose production and glycogenolysis by phenylephrine (2 microM) and isoproterenol (20 microM) was decreased in IIH. The changes in the responsiveness of glycogen catabolism were first observed for isoproterenol and later for phenylephrine. Hepatic ss-adrenergic receptors showed a higher degree of adrenergic desensitization than did alpha-receptors. Liver glycogen synthase activity, glycogen content and the catabolic effect of dibutyryl cyclic AMP (the ss-receptor second messenger) were not affected by IIH.

Adrenergic alpha-Agonists↗

PubMed2000

Rates of gluconeogenesis in perfused liver of alloxan-diabetic fed rats.

The maximal capacity of the liver to produce glucose was examined using a technique, which permited to investigate gluconeogenesis in diabetic fed rats. Diabetes was obtained with an iv injection of alloxan (40 mg/kg). Livers from diabetic fed rats were perfused in situ and gluconeogenesis from different glucose precursors were measured one week after alloxan injection. Hepatic gluconeogenesis from L-alanine (5 mM) was absent. However, increased urea, pyruvate and L-lactate production was observed during L-alanine infusion. Differently of L-alanine, alloxan-diabetic fed rats showed increased hepatic glucose production from pyruvate (5 mM), L-lactate (2 mM) and D-frutose (5 mM). Additionally, increased L-lactate production from pyruvate and pyruvate production from L-lactate were observed. However, pyruvate production from L-lactate was lower in the diabetic group when compared with control group. Moreover similar tendency were observed for L-alanine and D-frutose. Taken together our results demonstrate influence of the cytosolic redox potential (NADH/NAD+ ratio) in the metabolic fate L-alanine. Additionally, in contrast to L-alanine, diabetic rats not only showed increased rate of glucose production from L-glutamine (5 mM) but also higher values than control rats.

Alloxan↗

PubMed1999

Acute effects of leptin on glucose metabolism of in situ rat perfused livers and isolated hepatocytes.

OBJECTIVE: To investigate whether leptin interferes directly with glycogenolysis and gluconeogenesis in isolated rat hepatocytes and also in in situ rat perfused livers. ANIMALS: Male albino rats (200-250 g) were used in all experiments. MEASUREMENTS: D-glucose, L-lactate and pyruvate production. RESULTS: In the present study, no differences were found for the rates of glycolysis, as expressed by the areas under the curves, among control (24.2+5.0 mmol¿g), leptin (32.0+4.5 mmol¿g), glucagon (24.7+3.0 mmol¿g), and the leptin + glucagon (23.8+3.4 mmol¿g) groups. No difference was found for the rates of glycogenolysis between the control and the leptin perfused livers (15.2+3.9 and 15.0+3.2 mmol¿g, respectively). In the presence of glucagon, the areas under the curves for the rate of glycogenolysis rose to 108.6+3.8 mmol¿g. When leptin was combined with glucagon, the area under the curve for glycogenolysis was 43. 7+4.3 mmol¿g. In fact, leptin caused a reduction of almost 60% (P<0. 001) in the rate of glucagon-stimulated glycogenolysis. Under basal conditions, the addition of leptin (100 ng¿ml) to the incubation medium did not elicit any alteration in glucose production by isolated hepatocytes. However, in the presence of leptin, the production of glucose from glycerol (2 mM), L-lactate (2 mM). L-alanine (5 mM) and L-glutamine (5 mM) by the isolated hepatocytes was significantly reduced (30%, 30%, 23% and 25%, respectively). The rate of glucose production (glycogenolysis) by isolated hepatocytes was not different between the control and the leptin incubated groups (445.0+/-91.0 and 428.0+/-72.0 nmol¿106 cells¿h, respectively). CONCLUSION: We conclude that leptin per se does not directly affect either liver glycolysis or its glucose production, but a physiological leptin concentration is capable of acutely inducing a direct marked reduction on the rate of glucagon-stimulated glucose production in in situ rat perfused liver. Leptin is also capable of reducing glucose production from different gluconeogenic precursors in isolated hepatocytes.

Alanine↗

PubMed1999

Hypoglycemia induced by insulin increases hepatic capacity to produce glucose from gluconeogenic amino acids.

AIM: To investigate the hepatic capacity to produce glucose during hypoglycemia induced by insulin (HII). METHODS: Livers from 24-h fasted rats which received i.p. insulin (HII rats) or saline (control rats) were perfused in situ. The gluconeogenic substrates L-alanine (5 mmol/L), L-glutamine (5 mmol/L), L-lactate (2 mmol/L), and glycerol (2 mmol/L) were employed. The gluconeogenic activity was measured as the difference between rates of glucose released during and before the substrate infusion. In part of the experiments the production of urea was measured. Before the liver perfusion blood was collected for determination of glycemia and insulinemia. RESULTS: HII rats showed: (a) hypoglycemia and hyperinsulinemia; (b) increased hepatic capacity to produce glucose from L-alanine and L-glutamine; (c) increased hepatic ureogenesis from L-alanine and L-glutamine; and (d) increased hepatic glucose production from glycerol. However, hepatic glucose production from L-lactate was not affected by hypoglycemia. CONCLUSION: In spite of hyperinsulinemia the hepatic capacity to produce glucose from L-glutamine and L-alanine increased during HII. These results can be attributed to the higher hepatic catabolism of both amino acids, since the ability of the liver to produce glucose was not affected by hypoglycemia.

Alanine↗

PubMed1998

Slipped capital femoral epiphysis. A report of 4 cases occurring in one family.

We describe slipped capital femoral epiphysis in 4 members of a black, obese family, who were all first-degree relatives. The aetiology of slipped capital femoral epiphysis is unknown, although it is thought to be multifactorial. Genetic predisposition and environmental factors have been associated with the condition. A familial incidence with at least two cases in the same family has been reported. In epidemiological studies, this incidence ranges from 3% to 35%. Our cases were investigated in an attempt to find a possible aetiological genetic factor. A genetic predisposition with an autosomal dominant pattern of transmission is suggested, although environmental variables must be considered as provocative factors.

Adolescent↗

PubMed1998

Responsiveness of glycogen catabolism to adrenergic agonists during insulin-induced hypoglycemia in rat livers.

1. Insulin-induced hypoglycemia (IIH) promoted decreased responsiveness of hepatic glycogen catabolism to phenylephrine and isoproterenol, but not to glucagon and cyanide. 2. In addition, glycogen phosphorylase activity and glycogen levels were not affected by IIH. 3. It was concluded that hypoglycemia promoted changes in hepatic responsiveness to adrenergic agonists. 4. However, the ability of the liver to mobilize glycogen was not influenced by hypoglycemia.

Adrenergic Agonists↗

PubMed1998

Genetic polymorphism of properdin factor B (BF) in domestic rabbit.

Genetic polymorphism of plasma properdin factor B (BF) was detected in domestic rabbit, Oryctolagus cuniculus, by means of isoelectric focusing and immunoblotting. The analysis of 298 individuals, corresponding to one French and two Portuguese populations, revealed the existence of six alleles, of which BF*A, B and C were common alleles, and D, F and G were rare ones.

Alleles↗

PubMed1998

Changes in glycemia induced by exercise in rats: contribution of hepatic glycogenolysis and gluconeogenesis.

The participation of hepatic glycogenolysis and gluconeogenesis to the glycemic changes promoted by exercise was investigated. For this purpose, we employed swimming rats (2.5% body weight extra load attached to the tail, at 24 degrees C) using a favorable condition to measure hepatic glycogenolysis (fed rats) and a favorable condition to measure hepatic gluconeogenesis (fasted rats). This experimental approach permits us to compare the contribution of hepatic glycogenolysis and gluconeogenesis to glucose changes for a specific schedule of exercise. The animals were investigated at rest, after 5 minutes of swimming and after swimming to exhaustion. Our results show that hepatic glycogen has a crucial role to determine hyperglycemia during exercise. In contrast, hypoglycemia developed during exercise when glycogen was depleted. However, the ability of the liver to produce glucose from L-lactate, glycerol and L-glutamine was increased during exercise. Taken together, these findings suggest that the hepatic capacity to produce glucose from gluconeogenic substrates (except for L-alanine) was increased when hepatic glycogen stores were depleted. Thus, the increased capacity to produce glucose shown by livers from exercising rats must to be an important metabolic adaptation to protect against severe hypoglycemia.

Animals↗

PubMed1998

Swimming-exercise increases the capacity of perfused rat liver to produce urea from ammonia and L-glutamine.

We designed this study to determine whether the capacity of the liver to uptake ammonia and produce urea was affected by exercise (swimming at 24 degrees C with a 2.5% extra body-weight load). For this purpose, livers from sedentary rats at rest were perfused with a buffer containing increasing concentration of NH4Cl. The maximal hepatic capacity to produce urea was found at an NH4Cl concentration of 0.25 mM. Based on this finding all experiments with livers obtained from rats subject to swimming exercise were also carried out with a NH4Cl concentration of 0.25 mM. Thus, employing this concentration of ammonia, livers from sedentary and endurance trained rats, (for a period of 11 days ), that had either been resting or had been subjected to swimming exercise for 5 min or until exhaustion, were perfused in situ and ammonia uptake and urea production were measured. Clearly, both parameters were increased by exercise. However, these changes were not affected by swimming training. In addition, we demonstrate that the effect of an acute exercise on hepatic metabolism is not restricted to ammonia metabolism since livers from sedentary rats which had been subjected to swimming exercise for 5 min or until exhaustion showed higher urea production from L-glutamine. Our results also suggest that part of the changes in ureogenesis induced by exercise is mediated by cortisol (increased ammonia uptake) and part of the changes is mediated by glucagon (urea production).

Ammonia↗

PubMed1996

Synergistic effect of counterregulatory hormones during insulin-induced hypoglycemia in rats: participation of lipolysis and gluconeogenesis to hyperglycemia.

AIM: To study the synergistic effect of G (glucagon, 0.02 mg.kg-1), H (hydrocortisone, 20 mg.kg-1) and E (phenylephrine + isoproterenol, both 1 mg.kg-1) during insulin-induced hypoglycemia (IIH) in rats with 6 h of food deprivation (F6 group). METHODS: I (insulin, 1 U.kg-1) was injected i.p. and 30 min later saline (F6 + I group), H, G and E individually or combined (G + H, G + E, H + E and G + H + E) were all injected i.p. and all experiments started 1 h after I injection. RESULTS: The rise in glycemia with H + G + E was greater than the sum of the responses to i.p. H, G and E individually or in double combination plus any single hormone. This effect was reproduced by G + H + Iso (isoproterenol, 1 mg.kg-1), G + H + Iso + Met (metoprolol, 1 mg.kg-1) and G + H + Sal (salbutamol, 1 mg.kg-1). A clear relationship was shown between glycemia and free fatty acids levels. Liver gluconeogenesis from glycerol (2 mmol.L-1) was higher in the group which received G + H + beta-adrenergic agonist vs control rats (F6 or F6 + I groups). CONCLUSION: (a) Acute hyperglycemia is obtained from a condition of IIH by combined i.p. of G + H + beta-adrenergic agonists; (b) This effect cannot be ascribed to a single hormone, but is a consequence of the combined effects of these substances; (c) Blood insulin levels and liver glycogen have no participation; (d) Lipolysis mediated by a beta-adrenergic mechanism and gluconeogenesis from glycerol contribute to the hyperglycemia.

Animals↗