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Biomedical subjects

G Bueno

Publications and source records attributed to G Bueno.

At least 19 recordsLinked to original sources
PubMed2001

Three-dimensional segmentation of anatomical structures in MR images on large data bases.

In this paper an image-based method founded on mathematical morphology is presented in order to facilitate the segmentation of cerebral structures over large data bases of 3D magnetic resonance images (MRIs). The segmentation is described as an immersion simulation, applied to the modified gradient image, modeled by a generated 3D-region adjacency graph (RAG). The segmentation relies on two main processes: homotopy modification and contour decision. The first one is achieved by a marker extraction stage where homogeneous 3D-regions are identified. This stage uses contrasted regions from morphological reconstruction and labeled flat regions constrained by the RAG. Then, the decision stage intends to precisely locate the contours of regions detected by the marker extraction. This decision is performed by a 3D extension of the watershed transform. The method has been applied on a data base of 3D brain MRIs composed of fifty patients. Results are illustrated by segmenting the ventricles, corpus callosum, cerebellum, hippocampus, pons, medulla and midbrain on our data base and the approach is validated on two phantom 3D MRIs.

Databases as Topic↗
PubMed2001

A joint physics-based statistical deformable model for multimodal brain image analysis.

A probabilistic deformable model for the representation of multiple brain structures is described. The statistically learned deformable model represents the relative location of different anatomical surfaces in brain magnetic resonance images (MRIs) and accommodates their significant variability across different individuals. The surfaces of each anatomical structure are parameterized by the amplitudes of the vibration modes of a deformable spherical mesh. For a given MRI in the training set, a vector containing the largest vibration modes describing the different deformable surfaces is created. This random vector is statistically constrained by retaining the most significant variation modes of its Karhunen-Loève expansion on the training population. By these means, the conjunction of surfaces are deformed according to the anatomical variability observed in the training set. Two applications of the joint probabilistic deformable model are presented: isolation of the brain from MRI using the probabilistic constraints embedded in the model and deformable model-based registration of three-dimensional multimodal (magnetic resonance/single photon emission computed tomography) brain images without removing nonbrain structures. The multi-object deformable model may be considered as a first step toward the development of a general purpose probabilistic anatomical atlas of the brain.

Anatomy, Cross-Sectional↗
PubMed2000

Serum leptin concentrations in children with Prader-Willi syndrome and non-syndromal obesity.

There is limited information on the underlying physiological mechanisms promoting obesity in patients with Prader-Willi syndrome (PWS). The aim of this study was to investigate whether body fat regulation in children with PWS is similar to that in children with non-syndromal obesity and non-obese children. We studied three groups: 1) 72 non-obese children and adolescents; 2) 68 children with non-syndromal obesity; and 3) 11 patients with PWS. Height and weight were measured and body mass index (BMI) and BMI SDS were calculated. Fasting serum leptin concentrations were determined. Median leptin serum concentrations were similar in PWS patients and children with non-syndromal obesity. Median leptin serum concentrations were higher in these two groups than in the non-obese group. Log leptin serum concentrations and BMI SDS showed significant correlations in the three groups of patients; correlation coefficients were 0.525, 0.285 and 0.854, respectively. In conclusion, median leptin serum concentrations are similar in PWS patients and children with non-syndromal obesity. The relationship between log serum leptin concentrations and BMI SDS was different in the three groups of patients studied.

Adolescent↗
PubMed1999

[The costs of treatment with the new antidepressants in clinical practice].

OBJECTIVE: To assess if, in usual clinical practice, the patterns of use of new antidepressant are associated to different health resource utilisation. DESIGN: Naturalistic, retrospective, observational study. SETTING: Urban health center. PATIENTS: DSM-IIIR diagnostic criteria of depressive disorder and treatment with a new antidepressant (n = 328). INTERVENTIONS: Information on resource utilisation was collected in those patients treated with fluoxetine (FLX), fluvoxamine (FLV) sertraline (SER), paroxetine (PAR) and venlafaxine (VLF). Direct, indirect and total costs were compared according to the different patterns of use (stable therapy, upward dose titration, switching or augmentation) and according to the initially prescribed antidepressant. The follow-up period was 6 months. RESULTS: Direct and total daily costs of those patients with unestable therapy (upward dose titration, switching or augmentation) were 55% (p < 0.01) and 87% (p = 0.001) higher than for patients with stable therapy, respectively. Patients who initiated therapy on SER, VLF and PAR had 35% (p < 0.05), 80% (p < 0.05) and 37% (p < 0.05), respectively, higher average total costs per day than patients who initiated therapy with FLX. Regarding direct costs, patients who initiated therapy on SER and VLF had 48% (p < 0.001) and 58% (p < 0.05) higher average costs per day than patients who initiated therapy with FLX. CONCLUSIONS: New antidepressants show different patterns of use in a clinical practice setting, being FLX the agent more associated to a stable pattern of use. The pattern of use is associated to different health resource utilisation. Patients under stable therapy show lower health costs than those who need upward titration, switching or augmentation strategies. It is necessary to conduct randomized naturalistic studies to confirm these results.

Adult↗
PubMed1998

Intracavernous methoxamine in the treatment of priapism.

Methoxamine is an alpha-adrenergic drug, its unique pharmacokinetics and mechanism of action on alpha-1 receptors lead to consider it, similarly to phenylephrine, as a first-choice drug for treating drug-induced or veno-occlusive priapism. The experience obtained with its use in the management of three cases of priapism lasting over 7 h and one case of sustained rigid erection caused during anesthetic induction are reported.

Adrenergic alpha-Agonists↗
PubMed1997

[General features of the patient-physician relationship].

The communication between physicians and patients is often deficient. Little time is devoted to it and the patient receives scanty information with a low emotional content. Some features of our medicine can explain this situation. The rationalist and mechanistic biological model, allows to study only those things that can be undertaken with the scientific method. Psychological, social and spiritual aspects are surpassed. It only looks at material aspects of people, limiting the communication. Patients express their symptoms in an emotional way, with multiple beliefs and fears. The physician converts them to a precise, scientific, measurable and rational medical logical type. This language is not understood by patients, generating hesitancy in the communication. The paternalism is based in the power that physicians have over patients. We give knowledge and ask the patient to subordinate and accept our power. The patient loses his moral right to be informed, to ask, to have doubts or to disagree. Our personal communication is almost always formal, unemotional and with no explanations, further limiting communication.

Communication↗
PubMed1995

Displacement threshold hyperacuity as a predictor of postsurgical visual performance in patients with cataract.

PURPOSE: To evaluate the ability of Displacement Threshold Hyperacuity (DTH) in predicting the postoperative visual outcome in patients awaiting cataract surgery and discriminating between the relative performance of the neural and optical components of the visual system. To establish eventually the cut-off DTH values to be used clinically in the preoperative evaluation of patients with cataract. METHODS: Forty-five subjects admitted for extracapsular cataract extraction with implant were examined preoperatively and postoperatively. In addition to DTH, logMAR visual acuity (VA), contrast sensitivity, and a cataract classification system were used to obtain a more comprehensive assessment of the patient's visual performance. RESULTS: DTH was found to be sensitive to decreased macular function but relatively unaffected by the severity of the cataract; higher thresholds were associated with denser opacities. A preoperative threshold of 50 seconds of arc was found to be the upper limit under which normal macular function is likely. DTH sensitivity and specificity for decreased macular function was 1.00 and 0.8, respectively. CONCLUSIONS: If preoperative DTH is 50 seconds of arc or lower, the subject will achieve a postoperative logMAR VA better than 0.3 (Snellen equivalent 20/40). On the contrary, higher DTH seems to give no reliable information about the patient's visual function.

Aged↗
PubMed1993

Clinical and hemodynamic predictors of survival in patients aged < 65 years with severe congestive heart failure secondary to ischemic or nonischemic dilated cardiomyopathy.

To identify which clinical or hemodynamic parameters predict survival in patients with end-stage heart failure due to dilated cardiomyopathy, 130 consecutive patients aged < 65 years (mean 46 +/- 13) assessed for heart transplantation from May 1986 to April 1991 were studied. Mean follow-up was 15 +/- 11 months. Left ventricular ejection fraction was 22 +/- 7%. Left ventricular end-diastolic pressure was 27 +/- 9 mm Hg, and cardiac index was 2.2 +/- 0.6 liter/min/m2. Symptom class was IV in 91% of patients and III in 9%. Etiology was ischemic in 40% of patients and idiopathic in 60%. After intensive medical therapy, heart transplantation was considered indicated in 53% of patients, contraindicated in 20% and not indicated in 27%. Transplantation was performed in 36% of patients during follow-up, and 35% died and 29% were alive without transplantation. A comparison, excluding patients with transplantation, was performed between those who were alive and had survived > or = 6 months after assessment, and those who died. On multivariate analysis, the following 3 parameters were independent predictors of prognosis: intravenous inotropic requirement (p < 0.001), maximal, tolerated captopril dose (p = 0.013) and systolic blood pressure (p = 0.003). When patients with transplantation were considered as deaths, stabilization on medical therapy also reached statistical significance (p = 0.009). Classic prognostic markers including ventricular arrhythmias, left ventricular end-diastolic pressure, cardiac index, amiodarone therapy and etiology were not associated with prognosis in this homogeneous population of severely ill patients.

Adolescent↗
PubMed1993

Evolution of height and bone age in primary congenital hypothyroidism.

Thyroid hormones are fundamental for growth and bone maturity. Retarded physical and osseous development signals congenital hypothyroidism. This study assessed the evolution of height and bone age and final height after hormone replacement treatment in 25 patients with primary congenital hypothyroidism. Bone ages, measured periodically for 12 years after treatment began, were expressed as standard deviation scores (SDS) corresponding to chronologic age. Heights were expressed as SDS and related to standardized curves and genetic height. All patients experienced height recovery during the first year. Of 19 patients who reached their final height, 16 surpassed the expected mean for genetic height. Bone age accelerated progressively, with total recovery toward the third year, and remained accelerated, reaching +1.43 +/- 1.27 in relation to chronologic age 12 years after hormone replacement began. Thus, early diagnosis and adequate treatment of congenital hypothyroidism improved growth and osseous development, although progressive acceleration of bone age may have limited final height in some children.

Age Determination by Skeleton↗
PubMed1993

[Patients with an acute myocardial infarct treated in a coronary unit or in a general cardiology ward A comparative study].

INTRODUCTION AND OBJECTIVES: Coronary care units have been accepted as the standard location for treatment for patients with acute myocardial infarction. Nevertheless, controversy over their clinical impact, current role and cost-effectiveness still remains. Due to the increased incidence of coronary artery disease in Spain, coronary care units are often full, and patients with acute myocardial infarction must be cared for in a general cardiology ward. METHODS: We have studied the features and results of 420 patients with acute myocardial infarction consecutively admitted to our hospital and compared patients cared for in the coronary care unit (329 [78%]) with those cared for in the cardiology ward (91 [22%]). Admission to cardiology ward or coronary care unit was based on the clinical judgment of emergency room physicians and the bed availability. No differences in age, sex, risks factors, prior history of coronary heart disease, blood pressure on admission, extension and complications of myocardial infarction were found between both groups. RESULTS: The percentage of patients with evolved and non-Q wave acute myocardial infarction, and admission electrocardiogram not suggestive of infarction was significantly higher in ward group (23 versus 2.4%, p < 0.001; 19 versus 11%, p < 0.01; and 43 versus 15%, p < 0.01; respectively). Although patients admitted to the coronary care unit underwent intravenous thrombolysis and coronary artery revascularization procedures in a higher proportion, mortality was similar in both groups (14% for ward patients and 17% for coronary care unit patients). When patients with evolved or non-Q wave infarctions and those with admission electrocardiograms not suggestive of infarction were excluded from the analysis, mortality rates remained similar. Subgroups mortality was in general similar for patients cared for in cardiology ward or in coronary care unit, although patients without shock, with Killip class I or II, and older than 70 years, had a slightly lesser mortality when treated in the Cardiology ward (5 versus 11%, 6 versus 11%, and 14 versus 28%, respectively). By contrast, patients with shock, Killip class III or IV, and electrocardiogram at admission not suggestive of infarction, had a lesser mortality when cared for in coronary care unit. CONCLUSIONS: We conclude that some subgroups of patients with acute myocardial infarction can be, if needed, effective and safely cared for in cardiology ward.

Aged↗
PubMed1992

Spontaneous clinical and hemodynamic improvement in patients on waiting list for heart transplantation.

Heart transplantation is currently the most effective therapy for patients with severe heart failure due to dilated cardiomyopathy, although long-term survival without transplantation has been described in a few patients. We have identified five patients with severe heart failure who experienced a significant clinical and hemodynamic improvement while they were waiting for heart transplantation. At initial assessment, all five patients were symptom-class 4; left ventricular end-diastolic pressure was 33 +/- 4 mm Hg, left ventricular ejection fraction was 0.20 +/- 0.01, left ventricular end-systolic volume was 130 +/- 3 ml/min/m2, and cardiac index was 2.1 +/- 0.1 L/min/m2. These patients showed a marked improvement at two to ten months after initial assessment, while they were waiting for a donor heart. After a follow-up of 10 to 31 months (mean follow-up, 20 months), the five patients were still alive and their clinical and hemodynamic condition remained stable. On the contrary, survival was less than 15 percent at six months for the remaining patients with indications for heart transplantation but in whom transplant could not be performed because of the existence of contraindications or lack of donors; all these patients were dead at 18 months after initial assessment. The five patients who developed spontaneous favorable outcome showed a trend to have higher serum sodium values, shorter symptomatic history, lesser need for intravenous inotropic support, and better response to medical therapy than the other patients. Our findings suggest that some patients with transplants could have experienced a sustained and spontaneous clinical and hemodynamic recovery with medical therapy alone, although it seems currently difficult to identify patients with this favorable outcome.

Adult↗
PubMed1992

[Spontaneous remission in a patient with long-term idiopathic dilated myocardiopathy].

The case of a patient with long-term idiopathic dilated cardiomyopathy, functional class IV, very depressed left ventricular ejection fraction (13%) and history of severe dyspnea for more than four years, who experienced an spontaneous clinical and hemodynamic recovery (functional class I, left ventricular ejection fraction 51%) while being on waiting list for heart transplantation is reported. The patient remains in good clinical condition after a follow-up of two years.

Cardiomyopathy, Dilated↗
PubMed1991

[The management by medical treatment of an intracranial mycotic aneurysm in a patient with infectious endocarditis with negative blood cultures and hypertrophic myocardiopathy].

A case of intracranial mycotic aneurysm due to culture-negative infective endocarditis involving a patient with hypertrophic cardiomyopathy is reported. The patient, a 22-year-old woman with no history of known prior disease, had fever, headache and focal neurologic symptoms 3 days before admission. An echocardiogram performed after admission disclosed an obstructive hypertrophic cardiomyopathy and a gross vegetation on septal leaflet of mitral valve. Cerebral angiography revealed a mycotic aneurysm involving a peripheral branch of the left middle cerebral artery. Causal agent was not identified, and empiric treatment with penicillin G and streptomycin achieved medical cure and disappearance of the aneurysm 2 weeks later. Four months after endocarditis had been cured, the patient was electively operated because of progression of mitral regurgitation. Six months later, she is asymptomatic.

Adult↗
PubMed1991

[Digitalis poisoning from medicinal herbs. Two different mechanisms of production].

Two cases of digitalis toxicity due to uncontrolled ingestion of medicinal herbs are presented. The first of them was caused by oleander (Nerium oleander); digoxinemia levels were very high in this patient (4.44 ng/l), who presented many brady- and tachyarrhythmias. These arrhythmias disappeared when digoxinemia returned to normal values. The second patient had atrial fibrillation with slow ventricular rate, severe hypokalemia (2.1 mEq/l) and normal digoxinemia levels. He was taking medicinal herbs for a cold, with sorbitol between its components. Sorbitol may be similar to mannitol and glycerol (osmotic diuretic drugs) when taken at high doses. Uncontrolled ingestion of medicinal herbs is not safe, and severe poisoning can occur.

Adult↗
PubMed1990

[Infarct size determination using enzymatic methods in patients with early coronary recanalization].

To evaluate the usefulness of the infarct size determined by serial creatine kinase (CPK) measurements in patients with early reperfusion, we have studied 189 patients meaning in age 59.2 +/- 8.6 years, with acute myocardial infarction treated with streptokinase (STK); 81 of them by intracoronary route (group A), and 108 by intravenous administration (group B). In the group A we performed serial angiographic studies in the following conditions: baseline, immediately after STK infusion and before hospital discharge. In group B we performed only one angiographic control 5 +/- 3 days after. In patients with reperfusion, the parameters of left ventricular function correlated with cumulative creatine kinase release (MAX-CPKr) by linear regression in both groups. We observed a tendency to closer correlations in patients with left anterior descending or circumflex artery as the infarct related artery, in patients without previous infarction and in those who did not receive electrical shock for ventricular arrhythmias. In patients with unsuccessful reperfusion (n = 11), we also obtain a significant correlation (r = 0.72) between ejection fraction and MAX-CPKr. The slope of the regression line (b = 7.7 X 10(-5) was steeper (p less than 0.05) than that observed in recanalized patients, who were evaluated within the first 3 days (b = 2.2 X 10(-5), after 8 +/- 5 days (b = 2.7 X 10(-5), or before discharge, at 22 +/- 9 days (b = 2.6 X 10(-5).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗