[Interobserver correlation in the interpretation of 99mTc-sestamibi SPECT in reperfused acute myocardial infarction]. / Correlación interobservadores en interpretación de SPECT de perfusión con 99mTc-sestamibi en infarto agudo de miocardio reperfundido.

INTRODUCTION AND OBJECTIVES: The correct interpretation of myocardial perfusion single photon emission computed tomography (SPECT) requires knowledge of the technique reproducibility. The objective was analyze the interobserver correlation of different experience in the interpretation of myocardial perfusion SPECT in patients following acute myocardial infarction (AMI) in order to improve the quality of our site. METHODS: Sixty cases (56 +/- 11 years, 87 % men) with transmural AMI who had recently undergone successful thrombolysis were included. Resting perfusion with (99m)Tc-sestamibi was performed at one week post-AMI. ANALYSIS: Semiquantitative interpretation using 17 segment-model by 2 independent specialists and 5 observers, was performed blindly. Left ventricular ejection fraction (LVEF) was measured with isotopic ventriculography one month after AMI, with a mean of 38 %. RESULTS: Using independent and then agreed on perfusion analysis, average involved segments/patient was 9.3 +/- 4 and the sum of severity 25 +/- 13. Readings of other observers ranged from 7 +/- 3.7 to 9.4 +/- 3.9 and 16.7 +/- 9.7 to 24.6 +/- 13, respectively, consistent with the reading of the specialists of between 0.779-0.871 (kappa: 0.565-0.741). There was no significant difference when the number of segments were analyzed in 40 % of the cases and for intensity in 60 % of them in more experienced observers. Correlation with consensus reading for the number of segments ranged from 0.84 to 0.94 and for severity from 0.79 to 0.89. Identification of culprit arteries was acceptable, with r values between 0.612 and 0.683 and kappas between 0.629 and 0.656. Correlation of the number of involved segments and severity with LVEF performed one month after AMI was 0.73 and 0.74, respectively. CONCLUSIONS: There was good correlation in the interpretation of myocardial perfusion SPECT, with a significantly better fit in more experienced observers. This academic exercise was also helpful in improving our residents' skills in cardiology.

Image fusion in neuroradiology: three clinical examples including MRI of Parkinson disease.

Image data fusion has been developed over the last decade as an important additional visual diagnostic tool to integrate the growing amount of imaging data obtained from different medical imaging modalities. The overwhelming amount of digital information calls for data consolidation to improve clinical treatment strategies based upon anatomical and physiological imaging. Three different low level image data fusion techniques are described and their characteristics are illustrated with some rare yet key examples. We used MR images to show neurodegeneration in the cerebral peduncle of the midbrain and found that image data fusion using colors can be a valuable tool to visually assess and quantify the loss of neural cells in the Substantia Nigra pars compacta in Parkinson's disease.

Scorpion envenoming in two regions of Colombia: clinical, epidemiological and therapeutic aspects.

To determine clinical and epidemiological features of scorpion stings in two departments of Colombia, a descriptive study was performed in the hospitals of 10 towns from Antioquia (2 256 071 inhabitants) and five from Tolima (630 424 inhabitants). One hundred and twenty-nine cases were admitted during one year, 51 in Antioquia, 78 in Tolima and 41 were children less than 15 years old. Most stings (70.5%) occurred inside the house; 27.9% were on the hands and 26.4% on the feet. The scorpion species involved were Tityus pachyurus (51), Centruroides gracilis (31), T. fuehrmanni (29), T. asthenes (7) and Chactas spp. (1). In 10 cases the scorpion involved was not identified. Systemic envenoming signs (e.g. vomiting, tachypnea) were significantly more frequent in children than in adults (P < 0.05). Four children had hypertension, but none developed pulmonary oedema. One 3-year-old girl, stung by T. asthenes, had acute oedematous pancreatitis. Ninety-eight patients had mild envenoming. Moderate (27 patients) and severe (four patients) envenoming was significantly more frequent in children than in adults (P = 0.003; relative risk = 2.97). A pepsin-digested anti-Centruroides spp. antivenom was administered to 19 of 31 patients presenting systemic envenoming signs. No adverse reactions to antivenom were observed.

Neutralization of the edema-forming, defibrinating and coagulant effects of Bothrops asper venom by extracts of plants used by healers in Colombia.

We determined the neutralizing activity of 12 ethanolic extracts of plants against the edema-forming, defibrinating and coagulant effects of Bothrops asper venom in Swiss Webster mice. The material used consisted of the leaves and branches of Bixa orellana (Bixaceae), Ficus nymphaeifolia (Moraceae), Struthanthus orbicularis (Loranthaceae) and Gonzalagunia panamensis (Rubiaceae); the stem barks of Brownea rosademonte (Caesalpiniaceae) and Tabebuia rosea (Bignoniaceae); the whole plant of Pleopeltis percussa (Polypodiaceae) and Trichomanes elegans (Hymenophyllaceae); rhizomes of Renealmia alpinia (Zingiberaceae), Heliconia curtispatha (Heliconiaceae) and Dracontium croatii (Araceae), and the ripe fruit of Citrus limon (Rutaceae). After preincubation of varying amounts of each extract with either 1.0 microg venom for the edema-forming effect or 2.0 microg venom for the defibrinating effect, the mixture was injected subcutaneously (sc) into the right foot pad or intravenously into the tail, respectively, to groups of four mice (18-20 g). All extracts (6.2-200 microg/mouse) partially neutralized the edema-forming activity of venom in a dose-dependent manner (58-76% inhibition), with B. orellana, S. orbicularis, G. panamensis, B. rosademonte, and D. croatii showing the highest effect. Ten extracts (3.9-2000 microg/mouse) also showed 100% neutralizing ability against the defibrinating effect of venom, and nine prolonged the coagulation time induced by the venom. When the extracts were administered either before or after venom injection, the neutralization of the edema-forming effect was lower than 40% for all extracts, and none of them neutralized the defibrinating effect of venom. When they were administered in situ (sc at the same site 5 min after venom injection), the neutralization of edema increased for six extracts, reaching levels up to 64% for C. limon.

The dual-isotope ProstaScint imaging procedure: clinical experience and staging results in 145 patients.

PURPOSE: Whole-body, regional planar, and SPECT imaging using the In-111-labeled monoclonal antibody capromab pendetide (In-111 MAb; ProstaScint) has been shown to increase the detection of early disease spread in patients with prostate cancer. However, recognition of metastatic tumor sites can be difficult, especially if the involved nodes are near blood vessels. We have developed an alternate approach to the identification of metastatic sites that is based on a single simultaneous In-111 MAb and Tc-99m RBC SPECT acquisition of the pelvis and abdomen on day 5 after injection. We have also developed software that dynamically subtracts the Tc-99m RBC data set (vascular component) from the In-111 MAb data set (prostate and lymph node component), which allows for easier identification of metastatic sites. METHODS: We evaluated the effectiveness of ProstaScint for staging 145 patients with prostate cancer, 19 newly diagnosed and 126 with recurrence, using these two modifications. RESULTS: With clinical follow-up in 13 of 19 (68%) patients with primary disease, 10 of 13 (78%) had organ-confined disease. With follow-up in 64 of 126 (51%) patients with possible recurrent disease, 49 of 64 (77%) were found to have prostatic fossa activity only. Disease stage was deemed more advanced in 3 of 13 (22%) patients with primary cancer and in 13 of 64 (20%) of those with recurrent disease based on ProstaScint findings when all other imaging tests were inconclusive. Six patients with recurrent disease had negative results of their scans. In the 16 patients with more advanced disease, 3 of 59 lesions (5%) were documented as false positive, and there were no reported cases of false-negative findings. CONCLUSIONS: Using both the dual-isotope procedure and the subtraction analysis software with the ProstaScint examination provides additional information for staging primary and possibly recurrent prostate cancer compared with standard imaging techniques.

[Analog gamma camera digitalization computer system]. / Un sistema de digitalización de gamma cámaras analógicas.

OBJECTIVE: Digitalization of analogue gamma cameras systems, using special acquisition boards in microcomputers and appropriate software for acquisition and processing of nuclear medicine images is described in detail. MATERIAL AND METHODS: Microcomputer integrated systems interconnected by means of a Local Area Network (LAN) and connected to several gamma cameras have been implemented using specialized acquisition boards. The PIP software (Portable Image Processing) was installed on each microcomputer to acquire and preprocess the nuclear medicine images. A specialized image processing software has been designed and developed for these purposes. This software allows processing of each nuclear medicine exam, in a semiautomatic procedure, and recording of the results on radiological films. RESULTS: . A stable, flexible and inexpensive system which makes it possible to digitize, visualize, process, and print nuclear medicine images obtained from analogue gamma cameras was implemented in the Nuclear Medicine Division. Such a system yields higher quality images than those obtained with analogue cameras while keeping operating costs considerably lower (filming: 24.6%, fixing 48.2% and developing 26%.) CONCLUSIONS: Analogue gamma camera systems can be digitalized economically. This system makes it possible to obtain optimal clinical quality nuclear medicine images, to increase the acquisition and processing efficiency, and to reduce the steps involved in each exam.

Antiplasmodial effect of the venom of Crotalus durissus cumanensis, crotoxin complex and Crotoxin B.

The antiplasmodial activity of phospholipases A(2) (PLA(2)) isolated from different animals has been studied. We explored the in vitro anti Plasmodium falciparum effect of a fraction containing crotoxin, Crotoxin B and whole venom of the rattlesnake Crotalus durissus cumanensis. Fraction II (crotoxin complex) was obtained by size exclusion chromatography, whereas Crotoxin B was purified by RP-HPLC. The whole venom is active against the parasite at concentrations of 0.17±0.03 µg/ml, fraction II at 0.76±0.17 µg/ml and Crotoxin B at 0.6±0.04 µg/ml. Differences were observed in the cytotoxic activity against peripheral mononuclear cells, with Crotoxin B exhibiting the highest cytotoxicity. The concentration of Crotoxin B required to exert cytotoxic activity was higher than that required to exert antiplasmodial activity. Lethality in mice confirmed the higher toxicity and neurotoxicity of whole venom and fraction II, whereas Crotoxin B was not lethal at the doses tested. These results suggest the potential of Crotoxin B as a lead compound for antimalarial activity.

Clinical diagnostic clues in Crohn's disease: a 41-year experience.

Determining the diagnosis of Crohn's disease has been highly difficult mainly during the first years of this study carried out at the Pontificia Universidad Catolica (PUC) Clinical Hospital. For instance, it has been frequently confused with Irritable bowel syndrome and sometimes misdiagnosed as ulcerative colitis, infectious colitis or enterocolitis, intestinal lymphoma, or coeliac disease. Consequently, it seems advisable to characterize what the most relevant clinical features are, in order to establish a clear concept of Crohn's disease. This difficulty may still be a problem at other medical centers in developing countries. Thus, sharing this information may contribute to a better understanding of this disease. Based on the clinical experience gained between 1963 and 2004 and reported herein, the main clinical characteristics of the disease are long-lasting day and night abdominal pain, which becomes more intense after eating and diarrhoea, sometimes associated to a mass in the abdomen, anal lesions, and other additional digestive and nondigestive clinical features. Nevertheless, the main aim of this work has been the following: is it possible to make, in an early stage, the diagnosis of Crohn's disease with a high degree of certainty exclusively with clinical data?

Semi-automated assessment of left ventricular mass using transaxial Tc-99m Sestamibi SPECT imaging.

The "left ventricular mass" (LVM) using Tc-99m Sestamibi SPECT imaging may be a useful parameter to quantitatively assess the left ventricle and hence its function. The LVM was determined without reorienting the images along the long axis of the left ventricle. A comparison with reoriented SPECT images was then performed. The LVM showed the expected variations among different pathological heart conditions and the control subjects. The left ventricular mass obtained from non-reoriented tomographic views of the myocardium can be a useful index to quantitatively assess various heart conditions where the myocardium lacks perfusion either between rest and stress studies or similar conditions in longitudinal studies.

Medición del metabolismo de la glucosa en pacientes con miocardiopatía dilatada mediante tomografía de emisión de positrones con 18F-FDG: experiencia inicial / Measurement of glucose metabolism in patients with dilated cardiomyopathy by 18F-FDG PET

Introducción. La Fluor-18 deoxiglucosa (18F-FDG) ha sido utilizada en múltiples estudios para determinar la tasa de utilización de la glucosa en condiciones normales y patológicas. Actualmente se sabe que en la insuficiencia cardiaca el patrón metabólico se encuentra alterado. Materiales y métodos Se realizó medición del metabolismo glucocídico en 4 portadores de miocardiopatía dilatada y en 3 sujetos sanos, todos bajo una carga de hidratos de carbono vía oral (75gr). Se adquirieron imágenes dinámicas de tórax. La captación miocárdica se estimó a partir de las curvas tiempo-actividad en aurícula y ventrículo izquierdo utilizando el análisis gráfico de Patlak. Resultados. Los siete pacientes estudiados son de sexo masculino. La tasa de captación de la 18F-FDG para el grupo de pacientes con miocardiopatía dilatada fue 1,31 +/- 0,2 versus 1,26 +/- 0,37 ml/100gr/min en el grupo control. Conclusión. La medición del metabolismo cardiaco de la glucosa por medio de 18F-FDG PET es posible de realizar en un servicio clínico, permitiendo de esta forma determinar la repercusión fisiológica y los cambios del metabolismo miocárdico en diversas enfermedades además de la evaluación de terapia.

Introduction. Fluorine18 deoxyglucose (18F-FDG) has been used in numerous studies to determine the cardiac rate of glucose metabolism in normal and pathological conditions. It is known that during heart failure the metabolic pattern is altered. Patlack’s graphical analysis allows the assessment of heart muscle glucose consumption in patients with non-ischaemic heart failure and normal subjects. Methods. Standardized measurement of glucose metabolism was performed in four patients with dilated cardiomyopathy and three healthy subjects. All subjects received an oral load of carbohydrates (75gr) previous to scanning. Dynamic images of the thorax were acquired. Myocardial uptake was estimated from time-activity curves in the atrium and left ventricle using Patlack’s graphical analysis. Results. All subjects studied were male. 18F-FDG uptake rate for the group with dilated cardiomyopathy was 1.31 +/-0.2, versus 1.26 +/- 0.37 ml/100gr/min in the control group. Conclusion. Measurement of cardiac glucose metabolism by 18F-FDG PET is feasible in a clinical service, allowing impact evaluation of physiologic and metabolic changes in the myocardium in different pathologic scenarios in addition to therapy assessment.

[Reversible myocardial ischemia in hypothyroidism: Case report]. / Isquemia miocárdica reversible en el hipotiroidismo: comunicación de un caso.

A silent, reversible myocardial ischemia with normal coronary angiography and reversible with thyroid hormone substitution, has been recently described in hypothyroid patients. We report a 49 years old male with an abnormal exercise electrocardiogram detected in a preventive medical examination. He had laboratory evidence of hypothyroidism and a history of two years of asthenia and progressive coarsening of the voice. The Thallium myocardial perfusion study, showed an alteration of coronary flow during exercise in the septum and lower wall of the left ventricle. Thyroid hormone substitution was started and three months later, a coronary angiography was normal. After six months a repeated Thallium perfusion study and exercise electrocardiogram were informed as normal.

Treatment of acute infantile diarrhoea with a commercial rice-based oral rehydration solution.

This randomized clinical trial compared the efficacy of an oral rehydration solution (ORS) formulated with commercial rice powder, 50 g/l, with that of a glucose-based WHO/UNICEF-recommended ORS in the management of 48 inpatients aged 3-24 months, with acute dehydrating watery diarrhoea. Stool outputs were generally high in these patients, and 11 patients (22%) required additional intravenous rehydration solutions. The stool output (ml/kg) in the first 24 hours was [geometric mean, (95% confidence intervals)] 213 (153-353) in the rice-ORS group versus 146 (108-232) in the glucose-ORS group, while the total stool output was 455 (298-933) versus 307 (209-625); (p value not significant). The mean (+/- SD) duration of diarrhoea in hospital was: 72 +/- 10 hours in the study group versus 77 +/- 12 hours in the control group (p value NS). Enteropathogens were found in 94% of the patients, rotavirus being prevalent in 85% of the cases. It is concluded that the rice-ORS used in this trial is no more efficacious than the standard glucose-ORS advocated by WHO/UNICEF in the treatment of infants with watery non-cholera dehydrating diarrhoea. In some cases, ORS formulated with the commercial cereal-based products might actually increase the stool losses in infants with high-output non-cholera diarrhoea.

PIP: A randomized clinical trial compared the efficacy of an oral rehydration solution (ORS) formulated with commercial rice powder at 50 g/l (case group of 13 boys and 11 girls) with that of glucose-based WHO/UNICEF-recommended ORS (control group of 13 boys and 11 girls) in the management of 48 patients aged 3-24 months with acute dehydrating watery diarrhea in the pediatric ward of the Universidad Catolica Clinical Hospital, Chile. Enteropathogens were found in 94% of the patients. Rotavirus was present in 85% of the patients, either as a single pathogen (58%) or in association with other agents (27%). Enteropathogenic Escherichia coli (EPEC) was recovered in 33% of the patients; in 8% of the cases it occurred as a single pathogen and in 25% of the cases it was associated with rotavirus. 7 patients (29%) in the control group and 4 (17%) in the study group required intravenous fluids at some point in the course of the study. Mean fecal losses were generally higher in the rice-ORS patients throughout the study. The stool output (ml/kg) in the first 24 hours was 213 (153-353) [geometric mean (95% confidence interval)] in the rice-ORS group vs. 146 (108-232) in the glucose-ORS group, while the total stool output was 455 (298-933) vs. 307 (209-625) (p value not significant). The mean [+or- standard deviation (SD)] duration of diarrhea in hospital was: 72 +or- 10 hours in the study group vs. 77 +or- 12 hours in the control group (p value not significant). The ORS formulated with a commercial rice powder used in this trial is not superior to the standard glucose-ORS advocated by WHO/UNICEF in the treatment of infants with watery non-cholera dehydrating diarrhea. In some cases, ORS formulated with the commercial cereal-based products might actually increase the stool losses in infants with high-output non-cholera diarrhea.

Incorporation of SPECT imaging in a longitudinal cognitive rehabilitation therapy programme.

In this clinical study, five consecutive referrals to a cognitive rehabilitation therapy (CRT) programme were followed in a longitudinal protocol involving a resting SPECT and neuropsychological evaluation at pre-treatment, post-treatment, and post non-treatment intervals. All clients had acquired brain injury and initially demonstrated neuropsychological deficits and various degrees of hypoperfusion on SPECT. Statistical Parametric Mapping (SPM) was used to evaluate change in successive SPECT images. Following CRT, all clients were able to return to productive employment or schooling. Examination of the neuropsychological testing results revealed significant improvement in performance following CRT which were generally maintained during the non-treatment period. SPM analysis of the SPECT data revealed that, in a majority of cases, most of the significant increases in relative cerebral blood flow redistribution were seen during the treatment period, rather than the non-treatment period. The results suggest that, even in individuals who are more than 2 years post-brain damage, relative increases in rCBF can be demonstrated following individualized CRT and that most of these changes can be related to improvements on neuropsychological tests.

[Effects of ramipril and spironolactone on ventricular remodeling after acute myocardial infarction: randomized and double-blind study]. / Ramipril vs espironolactona en el remodelamiento ventricular izquierdo post-infarto: estudio randomizado y doble ciego.

BACKGROUND: Studies have shown that angiotensin converting enzyme (ACE) inhibition prevents left ventricular remodeling and cardiovascular events after an acute myocardial infarction. The role of aldosterone in ventricular remodeling after a myocardial infarction has not been addressed. AIM: To compare the effects of an ACE inhibitor, an aldosterone receptor antagonist and placebo on left ventricular remodeling after a first episode of transmural acute myocardial infarction. PATIENTS AND METHODS: Patients hospitalized for a first episode of acute myocardial infarction were blindly and randomly assigned to receive ramipril (2.5 mg bid), spironolactone (25 mg tid) or placebo. Ejection fraction, left ventricular end diastolic and end systolic volumes were measured by multigated radionuclide angiography, at baseline and after six months of treatment. RESULTS: Twenty four patients were assigned to placebo, 31 to ramipril and 23 to spironolactone. Age, gender, Killip class, treatment with thrombolytics, revascularization procedures and use of additional medications were similar in the three groups. After six months of treatment, ejection fraction increased from 34.5 +/- 2.3 to 40.2 +/- 2.4% in patients on ramipril, from 32.6 +/- 2.9 to 36.6 +/- 2.7% in patients on spironolactone, and decreased from 37 +/- 3 to 31 +/- 3% in patients on placebo (ANOVA between groups p < 0.05). Basal end systolic volume was similar in all three groups, increased from 43.4 +/- 3.4 to 61.4 +/- 6.0 ml/m2 in patients on placebo and did not change in patients on spironolactone or ramipril (ANOVA p < 0.05). End diastolic volume was also similar in the three groups, increased from 70.6 +/- 4.3 to 92.8 +/- 6.4 ml/m2 in patients on placebo and did not change with the other treatments. CONCLUSIONS: Ramipril and spironolactone had similar effects on ventricular remodeling after acute myocardial infarction, suggesting that aldosterone contributes to this phenomenon and that inhibition of its receptor may be as effective as ACE inhibition in its prevention.

[Nationally produced 153SmEDTMP in the palliative treatment of metastatic bone cancer pain]. / 153SmEDTMP de producción nacional en el tratamiento paliativo del dolor óseo metastásico.

153SmEDTMP was obtained from enriched 152Sm irradiated at the 5 MW Chilean Research Reactor and labelled at a molar ratio of 15:1 pH 7.5. Biodistribution, autoradiography, radiochemical purity tests were done for evaluation. 40 patients were treated with 37-55 MBq/kg weight. Bone scans using 99mTcHMDP were obtained prior and after treatment. Bone marrow depression was observed in 37% of them and normal liver function in all of them. In 45% the pain dissapear completely, in 22.5% significantly decreased and partially in 30%. In 17 patients more than one dosis was injected. Our preliminary results indicate that 153SmEDTMP is a promising radiotherapeutic agent for palliative treatment of metastatic bone cancer pain and encourage its use specially because it can be produced in countries with low economic resources, thus a large number of patients can get the benefits of this new procedure.

[99mTc red blood cell scintigraphy for the assessment of active gastrointestinal bleeding]. / Rol de la cintigrafía con glóbulos rojos-Tc-99m en la evaluación de hemorragia digestiva alta.

BACKGROUND: 99mTc red blood cell scintigraphy is a non invasive diagnostic method for low flow gastrointestinal bleeding. AIM: To assess the diagnostic yield of this method in patients admitted with gastrointestinal bleeding in whom upper gastrointestinal endoscopy was negative. PATIENTS AND METHODS: The clinical records of 59 patients, aged 6 to 90 years old (35 male), with active gastrointestinal bleeding subjected to a 99mTc red blood cell scintigraphy were reviewed. All had non diagnostic upper gastrointestinal endoscopic studies, and in 20 a selective arteriography was performed. RESULTS: In 40 patients the scintigraphy was positive for gastrointestinal bleeding, and in 57% of these the exam was positive during the first hour. Fifteen of the 19 patients with a negative scintigraphy did not have an active clinical bleeding at the moment of the examination. In 24 patients, a final etiological diagnosis was reached. In 93% of these patients scintigraphy correctly identified the bleeding site. In one patient with a negative scintigraphy, angiography disclosed a pseudo aneurysm of the splenic artery that was not bleeding actively. CONCLUSIONS: In these patients with negative upper gastrointestinal endoscopy 99mTc red blood cell scintigraphy had a 91% sensitivity for the diagnosis of active gastrointestinal bleeding.

Status epiléptico no convulsivo: una entidad heterogénea de difícil diagnóstico. Reporte de dos casos con presentación inusual / Non convulsive status epilepticus: an heterogeneous disease with a difficult diagnosis. Report of 2 cases with unusual presentation

Non convulsive status epilepticus is a heterogeneous condition consisting of very different electroclinical syndromes. It is difficult to make the diagnosis and identify common factors among patients. We report two cases with an unusual presentation. A 31 years old woman having discoid lupus presented with a prolonged exogenous psychosis that lasted two and half months, associated to echolalia. After the episode the patient remained with a severe frontal syndrome that could be the consequence of a non convulsive status epilepticus. A 60 years old woman with an epilepsy diagnosed at the age of 30, presented with recurrent episodes of aphasia. During one of these crises, the electroencephalogram showed continuous epileptiform activity.

Neutralization of the edema-forming, defibrinating and coagulant effects of Bothrops asper venom by extracts of plants used by healers in Colombia

We determined the neutralizing activity of 12 ethanolic extracts of plants against the edema-forming, defibrinating and coagulant effects of Bothrops asper venom in Swiss Webster mice. The material used consisted of the leaves and branches of Bixa orellana (Bixaceae), Ficus nymphaeifolia (Moraceae), Struthanthus orbicularis (Loranthaceae) and Gonzalagunia panamensis (Rubiaceae); the stem barks of Brownea rosademonte (Caesalpiniaceae) and Tabebuia rosea (Bignoniaceae); the whole plant of Pleopeltis percussa (Polypodiaceae) and Trichomanes elegans (Hymenophyllaceae); rhizomes of Renealmia alpinia (Zingiberaceae), Heliconia curtispatha (Heliconiaceae) and Dracontium croatii (Araceae), and the ripe fruit of Citrus limon (Rutaceae). After preincubation of varying amounts of each extract with either 1.0 æg venom for the edema-forming effect or 2.0 æg venom for the defibrinating effect, the mixture was injected subcutaneously (sc) into the right foot pad or intravenously into the tail, respectively, to groups of four mice (18-20 g). All extracts (6.2-200 æg/mouse) partially neutralized the edema-forming activity of venom in a dose-dependent manner (58-76 percent inhibition), with B. orellana, S. orbicularis, G. panamensis, B. rosademonte, and D. croatii showing the highest effect. Ten extracts (3.9-2000 æg/mouse) also showed 100 percent neutralizing ability against the defibrinating effect of venom, and nine prolonged the coagulation time induced by the venom. When the extracts were administered either before or after venom injection, the neutralization of the edema-forming effect was lower than 40 percent for all extracts, and none of them neutralized the defibrinating effect of venom. When they were administered in situ (sc at the same site 5 min after venom injection), the neutralization of edema increased for six extracts, reaching levels up to 64 percent for C. limon.