Post hoc support vector machine learning for impedimetric biosensors based on weak protein-ligand interactions.

Impedimetric biosensors for measuring small molecules based on weak/transient interactions between bioreceptors and target analytes are a challenge for detection electronics, particularly in field studies or in the analysis of complex matrices. Protein-ligand binding sensors have enormous potential for biosensing, but achieving accuracy in complex solutions is a major challenge. There is a need for simple post hoc analytical tools that are not computationally expensive, yet provide near real time feedback on data derived from impedance spectra. Here, we show the use of a simple, open source support vector machine learning algorithm for analyzing impedimetric data in lieu of using equivalent circuit analysis. We demonstrate two different protein-based biosensors to show that the tool can be used for various applications. We conclude with a mobile phone-based demonstration focused on the measurement of acetone, an important biomarker related to the onset of diabetic ketoacidosis. In all conditions tested, the open source classifier was capable of performing as well as, or better, than the equivalent circuit analysis for characterizing weak/transient interactions between a model ligand (acetone) and a small chemosensory protein derived from the tsetse fly. In addition, the tool has a low computational requirement, facilitating use for mobile acquisition systems such as mobile phones. The protocol is deployed through Jupyter notebook (an open source computing environment available for mobile phone, tablet or computer use) and the code was written in Python. For each of the applications, we provide step-by-step instructions in English, Spanish, Mandarin and Portuguese to facilitate widespread use. All codes were based on scikit-learn, an open source software machine learning library in the Python language, and were processed in Jupyter notebook, an open-source web application for Python. The tool can easily be integrated with the mobile biosensor equipment for rapid detection, facilitating use by a broad range of impedimetric biosensor users. This post hoc analysis tool can serve as a launchpad for the convergence of nanobiosensors in planetary health monitoring applications based on mobile phone hardware.

How much does the specialist know about cardiogastroenterology? / ¿Cuánto sabe el especialista sobre cardiogastroenterología?

INTRODUCTION AND AIMS: Cardiovascular disease is a growing public health problem. Forty percent of the general population will suffer from the disease by 2030, consequently requiring antithrombotic therapy. Cardiogastroenterology is a new area of knowledge that evaluates the gastrointestinal effects and complications of antithrombotic therapy. Our aim was to evaluate, through a validated questionnaire, the knowledge held by a group of specialists and residents in the areas of gastroenterology and internal medicine, about pharmacology and drug prescription, as well as gastrointestinal risks and complications, in relation to antithrombotic therapy. PATIENTS AND METHODS: A validated questionnaire composed of 30 items was applied to a group of specialists and residents in the areas of gastroenterology and internal medicine. The questions were on indications, pharmacology, evaluation of risks for gastrointestinal bleeding and thromboembolic events, and use of antithrombotic therapy during endoscopic procedures. Sufficient knowledge was defined as 18 or more (≥ 60%) correct answers. RESULTS: The questionnaire was answered by 194 physicians: 82 (42%) internal medicine residents and gastroenterology residents and 112 (58%) specialists. Only 40 (20.6%) of the participants had sufficient knowledge of cardiogastroenterology. Residents had a higher number of correct answers than specialists (53 vs. 36%, P<.0001). The gastroenterology residents had more correct answers than the internal medicine residents, gastroenterologists, and internists (70 vs. 53, 40, and 46%, respectively, P<.001). Only residents had sufficient knowledge regarding pharmacology and the use of antithrombotic therapy in endoscopy (P<.0001). All groups had insufficient knowledge in evaluating the risk for gastrointestinal bleeding and thrombosis. CONCLUSIONS: Knowledge of cardiogastroenterology was insufficient in the group of residents and specialists surveyed. There is a need for medical education programs on the appropriate use of antithrombotic therapy.

Considerations for successful cancer immunotherapy in aged hosts.

Immunotherapy is now experiencing unprecedented successes in treating various cancers based on new understandings of cancer immunopathogenesis. Nonetheless, although ageing is the biggest risk factor for cancer, the majority of cancer immunotherapy preclinical studies are conducted in young hosts. This review will explore age-related changes in immunity as they relate to cancer immune surveillance, immunopathogenesis and responses to immunotherapy. Although it is recognized that declining T cell function with age poses a great challenge to developing effective age-related cancer immunotherapies, examples of successful approaches to overcome this hurdle have been developed. Further, it is now recognized that immune functions do not simply decline with age, but rather change in ways than can be detrimental. For example, with age, specific immune cell populations with detrimental functions can become predominant (such as cells producing proinflammatory cytokines), suppressive cells can become more numerous or more suppressive (such as myeloid-derived suppressor cells), drugs can affect aged immune cells distinctly and the aged microenvironment is becoming recognized as a significant barrier to address. Key developments in these and other areas will be surveyed as they relate to cancer immunotherapy in aged hosts, and areas in need of more study will be assessed with some speculations for the future. We propose the term 'age-related immune dysfunction' (ARID) as best representative of age-associated changes in immunity.

Localization and expression of TRPV1 and TRPA1 in the human oropharynx and larynx.

BACKGROUND: Previous studies have found that TRPV1 and TRPA1 receptor agonists improve swallow response in patients with oropharyngeal dysphagia (OD), but little is known about the expression of these receptors in the human oropharynx. The aim of this study was to assess the expression and localization of TRPV1 and TRPA1 in human samples from the oropharynx of healthy patients, to provide the basis for new pharmacological treatments for OD. METHODS: Samples from oropharyngeal regions innervated by cranial nerves V, IX, and X (tongue, pharynx, and epiglottis) were obtained during ENT surgery and processed either for mRNA (21 patients) or for immunohistochemical assays (seven patients). The expression analysis was performed with RT-qPCR using ACTBh as reference gene. Hemotoxylin and eosin staining was used to study the histology; the immunohistochemical assay used (i) neuron-specific enolase to detect nerve fibers or (ii) fluorescent probes to locate TRPV1 and TRPA1. RESULTS: TRPV1 was expressed in the three studied regions, with higher levels in CN V region (tongue) than in CN X region (epiglottis; p < 0.05), and was localized at epithelial cells and nociceptive fibers in all studied regions. TRPA1 was also expressed in all studied regions, but was always localized below the basal lamina. No immunoreactivity for TRPA1 was found on epithelial cells. CONCLUSIONS & INFERENCES: TRPV1 and TRPA1 are widely expressed in the human oropharynx with two distinct patterns. Our study further confirms that TRPV1/A1 receptors are promising therapeutic targets to develop active treatments for OD patients.

Management and outcomes in chronic thromboembolic pulmonary hypertension: From expert centers to a nationwide perspective.

BACKGROUND: The Spanish "Registry of Pulmonary Arterial Hypertension" (REHAP), started in 2007, includes chronic thromboembolic hypertension (CTEPH) patients. Based on data provided by this registry and retrospective data from patients diagnosed during 2006 (≤ 12 months since the registry was created), clinical management and long-term outcomes of CTEPH patients are analyzed nationwide for the first time in a scenario of a decentralized organization model of CTEPH management. METHODS AND RESULTS: A total of 391 patients (median [Q1:Q3] age 63.7 [48.0;73.3] years, 58% females) with CTEPH included during the period January 1, 2006-December 31, 2013 in the REHAP registry were analyzed. Rate of pulmonary endarterectomy (PEA) was 31.2%, and highly asymmetric among centers: rate was 47.9% at two centers designated as CTEPH expert centers, while it was 4.6% in other centers. Among patients not undergoing PEA, 82% were treated with therapies licensed for pulmonary arterial hypertension (PAH). Five-year survival rate was 86.3% for PEA patients, and 64.9% for non-PEA patients. Among non-PEA patients, presenting proximal lesions (42% of non-referred patients) was associated with a 3-fold increase in mortality. PEA patients achieved significantly better hemodynamic and clinical outcomes at one-year follow-up compared to non-PEA patients. Patients not being referred for PEA assessment were older and had a worse functional capacity. Older age was the most deterrent factor for non-operability. CONCLUSION: Despite the increase in diagnosis and expertise in PEA-specialized centers, an important percentage of patients do not benefit of PEA in a decentralized organization model of CTEPH management.

Specificity and sensitivity of visual evoked potentials in the diagnosis of schizophrenia: rethinking VEPs.

Alterations of the visual evoked potential (VEP) component P1 at the occipital region represent the most extended functional references of early visual dysfunctions in schizophrenia (SZ). However, P1 deficits are not reliable enough to be accepted as standard susceptibility markers for use in clinical psychiatry. We have previously reported a novel approach combining a standard checkerboard pattern-reversal stimulus, spectral resolution VEP, source detection techniques and statistical procedures which allowed the correct classification of all patients as SZ compared to controls. Here, we applied the same statistical approach but to a single surface VEP - in contrast to the complex EEG source analyses in our previous report. P1 and N1 amplitude differences among spectral resolution VEPs from a POz-F3 bipolar montage were computed for each component. The resulting F-values were then Z-transformed. Individual comparisons of each component of P1 and N1 showed that in 72% of patients, their individual Z-score deviated from the normal distribution of controls for at least one of the two components. Crossvalidation against the distribution in the SZ-group improved the detection rate to 93%. In all, six patients were misclassified. Clinical validation yielded striking positive (78.13%) and negative (92.69%) predictive values. The here presented procedure offers a potential clinical screening method for increased susceptibility to SZ which should then be followed by high density electrode array and source detection analyses. The most important aspect of this work is represented by the fact that this diagnostic technique is low-cost and involves equipment that is feasible to use in typical community clinics.

Basic visual dysfunction allows classification of patients with schizophrenia with exceptional accuracy.

Basic visual dysfunctions are commonly reported in schizophrenia; however their value as diagnostic tools remains uncertain. This study reports a novel electrophysiological approach using checkerboard visual evoked potentials (VEP). Sources of spectral resolution VEP-components C1, P1 and N1 were estimated by LORETA, and the band-effects (BSE) on these estimated sources were explored in each subject. BSEs were Z-transformed for each component and relationships with clinical variables were assessed. Clinical effects were evaluated by ROC-curves and predictive values. Forty-eight patients with schizophrenia (SZ) and 55 healthy controls participated in the study. For each of the 48 patients, the three VEP components were localized to both dorsal and ventral brain areas and also deviated from a normal distribution. P1 and N1 deviations were independent of treatment, illness chronicity or gender. Results from LORETA also suggest that deficits in thalamus, posterior cingulum, precuneus, superior parietal and medial occipitotemporal areas were associated with symptom severity. While positive symptoms were more strongly related to sensory processing deficits (P1), negative symptoms were more strongly related to perceptual processing dysfunction (N1). Clinical validation revealed positive and negative predictive values for correctly classifying SZ of 100% and 77%, respectively. Classification in an additional independent sample of 30 SZ corroborated these results. In summary, this novel approach revealed basic visual dysfunctions in all patients with schizophrenia, suggesting these visual dysfunctions represent a promising candidate as a biomarker for schizophrenia.

High-fat diet increases thyrotropin and oxygen consumption without altering circulating 3,5,3'-triiodothyronine (T3) and thyroxine in rats: the role of iodothyronine deiodinases, reverse T3 production, and whole-body fat oxidation.

This study investigated the effects of obesity induced by high-fat (HF) diet on thyroid function and whole-body energy balance. To accomplish that, we assessed the effects of 8 wk of HF diet on several parameters of hypothalamus-pituitary-thyroid axis function. Serum total T(4) and T(3), rT(3), and TSH, the activity of type 1 and type 2 deiodinases in central and peripheral tissues were determined. Also, we measured in vivo energy balance, substrate partitioning, and markers of leptin resistance. Here we provide novel evidence that prolonged positive energy balance acquired by feeding a HF diet induced hyperactivation of the hypothalamus-pituitary-thyroid axis, which was characterized by 2.24-, 1.6-, and 3.7-fold elevations in hypothalamic TRH expression, thyroid iodide uptake, and serum TSH, respectively. Serum T(4) and T(3) were normal together with augmented deiodinase type 1 activity in liver (1.3-fold) and kidney (1.2-fold) and increased (1.5-fold) serum rT3 in HF rats. Despite no increase in circulating levels of T(3) and T(4), whole-body oxygen consumption was increased, and substrate metabolism was shifted toward fat oxidation in HF rats. These in vivo metabolic adjustments were mainly driven by the fat content of the diet. Furthermore, spontaneous dark cycle physical activity was reduced by 30% in rats fed a HF diet, which limited energy expenditure and favored the development of obesity. Our findings provide new insight into the endocrine and physiological mechanisms that underlie the alterations in thyroid hormone availability, energy balance, and metabolic partitioning in HF diet-induced obesity.

Muerte súbita en pacientes esquizofrénicos en tratamiento con antipsicóticos / Sudden death in schizophrenic patients in treatment with antipsychotic

La intensidad y la evolución de la esquizofrenia dependen de la alteración de determinados centros neuronales y de la interacción entre la gravedad de tales alteraciones y las fluctuaciones de diversos neurotransmisores y neuromoduladores, entre ellos, la dopamina. Quizás debido a esta complejidad y heterogeneidad tanto en su causa como en su evolución, se dan casos de pacientes tratados con antipsicóticos, fisiológicamente estabilizados y de los que no se espera una evolución desfavorable que sufren un fallecimiento inesperado. En este sentido, se considera un caso de muerte súbita en un paciente que padecía hipertensión arterial, diabetes mellitus y esquizofrenia hebefrénica en tratamiento con tioridazina, sustancia que es determinada mediante cromatografía gaseosa acoplada a espectrometría de masas (GC-MS) detectándose la presencia de tioridazina en una concentración de 2,392 mg/L de sangre. Estudiando dicho caso y teniendo en cuenta otros similares se aportan consideraciones que pueden ser de utilidad en la evaluación de estos agentes terapéuticos(AU)

Schizophrenia intensity and its evolution depend on the alteration of certain neuronal centres and on the interaction among the severity of such alterations and the fluctuations of diverse neurotransmitters and neuromodulators, among them, dopamine. Maybe due this complexity and the heterogeneity both in its origin and in its evolution, it due patients' cases treated with antipsychotic, physiologically stabilized from that there is not hoped an unfavorable evolution that they suffer an unexpected death. In this sense, one case is considered with fatal conclusion in a patient who was enduring arterial hypertens ion, diabetes mellitus and hebephrenic schizophrenia in treatment with thioridazine. This substance is analyzed by gas chromatography in tandem with mass spectrometry (GC/MS) found a sanguineous level of 2,39 mg/L. Studying the above mentioned case and taking account others similar; it can be obtained considerations that could be useful in the evaluation of these therapeutic agents(AU)

[Prognostic estimation in critical patients. Validation of a new and very simple system of prognostic estimation of survival in an intensive care unit]. / Estimación pronóstica en enfermos críticos. Validación de un nuevo y muy sencillo sistema de estimación pronóstica de supervivencia en pacientes ingresados en una Unidad de Cuidados Intensivos.

OBJECTIVE: To make the validation of a new system of prognostic estimation of survival in critical patients (EPEC) seen in a multidisciplinar Intensive care unit (ICU). DESIGN AND SCOPE: Prospective analysis of a patient cohort seen in the ICU of a multidisciplinar Intensive Medicine Service of a reference teaching hospital with 19 beds. PATIENTS AND METHOD: Four hundred eighty four patients admitted consecutively over 6 months in 2003. Data collection of a basic minimum data set that includes patient identification data (gender, age), reason for admission and their origin, prognostic estimation of survival by EPEC, MPM II 0 and SAPS II (the latter two considered as gold standard). Mortality was evaluated on hospital discharge. EPEC validation was done with analysis of its discriminating capacity (ROC curve), calibration of its prognostic capacity (Hosmer Lemeshow C test), resolution of the 2 x 2 Contingency tables around different probability values (20, 50, 70 and mean value of prognostic estimation). The standardized mortality rate (SMR) for each one of the methods was calculated. Linear regression of the EPEC regarding the MPM II 0 and SAPS II was established and concordance analyses were done (Bland-Altman test) of the prediction of mortality by the three systems. RESULTS: In spite of an apparently good linear correlation, similar accuracy of prediction and discrimination capacity, EPEC is not well-calibrated (no likelihood of death greater than 50%) and the concordance analyses show that more than 10% of the pairs were outside the 95% confidence interval. CONCLUSION: In spite of its ease of application and calculation and of incorporating delay of admission in ICU as a variable, EPEC does not offer any predictive advantage on MPM II 0 or SAPS II, and its predictions adapt to reality worse.

Estimacion pronostica en enfermos criticos. Validacion de un nuevo y muy sencillo sistema de estimación pronóstica de supervivencia en pacientes ingresados en una Unidad de Cuidados Intensivos / Prognostic estimation in critical patients. Validation of a new and very simple system of prognostic estimation of survival in an Intensive Care Unit

Objetivo. Realizar la validación de un nuevo sistema de estimación pronóstica de supervivencia de enfermos críticos (EPEC) atendidos en una Unidad de Cuidados Intensivos (UCI) polivalente. Diseño y ámbito. Análisis prospectivo de una cohorte de pacientes atendidos en la UCI de un Servicio de Medicina Intensiva polivalente de un hospital docente de referencia, dotado de 19 camas. Pacientes y método. Cuatrocientos ochenta y cuatro pacientes ingresados consecutivamente durante 6 meses de 2003. Recogida de datos de un conjunto mínimo básico de datos (CMBD) propio que incluye datos de identificación de pacientes (género, edad, etc.), motivo de ingreso y procedencia del mismo, estimación pronóstica de supervivencia mediante EPEC, MPM II 0 y SAPS II (considerados estos dos como gold standard). La mortalidad fue evaluada al alta hospitalaria. La validación de EPEC fue realizada mediante análisis de su capacidad discriminante (curvas ROC); la calibración de su capacidad pronóstica (test de Hosmer Lemeshow C) y resolución de las tablas de contingencia 2 x 2 alrededor de distintos valores de probabilidad (20, 50, 70 y valor medio de la estimación pronóstica). Se calculó la tasa estandarizada de mortalidad (SMR) para cada uno de los métodos. Se estableció la regresión lineal de EPEC respecto de MPM II 0 y SAPS II y se realizaron análisis de concordancia (test de Bland-Altman) de la predicción de mortalidad por los tres sistemas. Resultados. A pesar de una aparentemente buena correlación lineal, una exactitud de predicción y una capacidad de discriminación similares, EPEC no está bien calibrado (ninguna probabilidad de muerte superior al 50%) y los análisis de concordancia demuestran que más del 10% de los pares están fuera del intervalo de confianza del 95%. Conclusión. A pesar de su sencillez de aplicación y cálculo y de incorporar como variable el retraso de ingreso en UCI, EPEC no ofrece ninguna ventaja predictiva sobre MPM II 0 o SAPS II, y sus predicciones se ajustan peor a la realidad

Objective. To make the validation of a new system of prognostic estimation of survival in critical patients (EPEC) seen in a multidisciplinar Intensive care unit (ICU). Design and scope. Prospective analysis of a patient cohort seen in the ICU of a multidisciplinar Intensive Medicine Service of a reference teaching hospital with 19 beds. Patients and method. Four hundred eighty four patients admitted consecutively over 6 months in 2003. Data collection of a basic minimum data set that includes patient identification data (gender, age), reason for admission and their origin, prognostic estimation of survival by EPEC, MPM II 0 and SAPS II (the latter two considered as gold standard). Mortality was evaluated on hospital discharge. EPEC validation was done with analysis of its discriminating capacity (ROC curve), calibration of its prognostic capacity (Hosmer Lemeshow C test), resolution of the 2 x 2 Contingency tables around different probability values (20, 50, 70 and mean value of prognostic estimation). The standardized mortality rate (SMR) for each one of the methods was calculated. Linear regression of the EPEC regarding the MPM II 0 and SAPS II was established and concordance analyses were done (Bland-Altman test) of the prediction of mortality by the three systems. Results. In spite of an apparently good linear correlation, similar accuracy of prediction and discrimination capacity, EPEC is not well-calibrated (no likelihood of death greater than 50%) and the concordance analyses show that more than 10% of the pairs were outside the 95% confidence interval. Conclusion. In spite of its ease of application and calculation and of incorporating delay of admission in ICU as a variable, EPEC does not offer any predictive advantage on MPM II 0 or SAPS II, and its predictions adapt to reality worse

[The non Q wave myocardial infarction in conventional valvular surgery. Diagnosis with cardiac troponin I]. / El infarto sin onda Q en cirugía cardíaca valvular convencional. Diagnóstico mediante la troponina I cardíaca.

INTRODUCTION: Morbidity and mortality in elective valve surgery is still significant. The main cause of death in these patients is cardiogenic shock, of which the most frequent etiology is acute myocardial infarction (AMI) with Q wave in the ECG. However, there are patients with cardiogenic shock without Q wave in the ECG and with rises in CK-MB enzyme that makes us suspect non-Q wave AMI. OBJECTIVE: To analyze the use of the determination of cardiac troponin-I, a more specific marker of AMI than CK-MB after cardiac surgery, to detect perioperative non-Q wave AMI, and to establish its clinical significance. METHODS: A total of 147 patients without coronary artery disease scheduled for elective valve surgery were included. We used, based in anterior publications, ECG (presence or not of new Q wave) and cardiac troponin I to define perioperative AMI. Levels of cardiac troponin-I were analysed before surgery and 14 hours after. Non-Q wave AMI was diagnosed when troponin I was superior to 38.85 ng/ml and there was not a phatologic Q wave in ECG. RESULTS: One hundred twenty-three (83.67%) of patients did not have AMI, 9 (6.12%) suffered perioperative AMI with Q wave, and 15 (10.27%) carried out criteria of non-Q wave perioperative AMI. Morbidity and mortality in this last group was similar to that in the group with Q wave AMI. Morbidity and mortality were minimum in patients without AMI. CONCLUSIONS: This study suggest the possibility of in vivo identification of non-Q wave perioperative AMI, an entity with important morbidity and mortality in our series, with a simple determination of cardiac troponin I 14 hours after surgery.

[Right ventricular cardiomyopathy: a diagnosis to bear in mind]. / Miocardiopatía ventricular derecha: un diagnóstico a tener en cuenta.

Arrhythmogenic right ventricular cardiomyopathy is a entity of unknown etiology, that is pathologically characterized by right ventricular myocardial atrophy and fibroadipous tissue replacement. We present the case of a 65-year-old male patient with the diagnosis of chronic liver disease, whose study lead a diagnosis of Arrhythmogenic right ventricular cardiomyopathy.

Aristophenones A and B. A new tautomeric pair of polyisoprenylated benzophenones from Garcinia aristata.

A tautomeric pair of new isoprenylated benzophenones, aristophenone A (1a) and B (1b), have been isolated from Garcinia aristata fruits. Their structures has been determined using high-field 2D NMR techniques.

Miocardiopatia Ventricular Derecha: un diagnostico a tener en cuenta / Right Ventricular Cardiomyopathy: a diagnosis to bear in mind

La miocardiopatía arritmogénica ventricular derecha es una entidad de etiopatogenia desconocida, que patológicamente se caracteriza por atrofia miocárdica ventricular derecha y sustitución por tejido fibroadiposo. Presentamos un paciente de 65 años de edad diagnosticado de hepatopatía crónica, cuyo estudio llevó al diagnóstico de miocardiopatía arritmogénica ventricular derecha. (AU)

[Stereotaxic biopsy and 192Ir implant in intracranial tumors. A review of 7 years of experience]. / Biopsia estereotáxica e implante de Ir-192 en tumores intracraneales. Revisión de 7 años de experiencia.

INTRODUCTION: The combination of stereotaxic techniques, advances in neuroimaging and the creation of continually improving software has permitted stereotaxic biopsy of cerebral lesions at the most varied sites. Improvement in the method of permanent interstitial radiation (brachytherapy) improves the precision with which the radioactive sources may be inserted, releasing a maximum dose of radiation to the tumour with minimum radiation to the surrounding tissue. PATIENTS AND METHODS: We treated 237 patients (aged 1 to 78 years) with intracranial lesions, all included in the protocol of our centre. Stereotaxic systems of Leksell, Riechert-Mundinger, Micromar and Estereoflex were used. The procedure was in three stages: acquisition of the image, surgical planning and surgical operation. The imaging guide was the computerized axial tomography (CAT). RESULTS: Stereotaxic biopsy guided by CAT images was done in 153 patients. These were divided into three groups, taking the biopsy findings as the reference: group A (primary tumors, 128), group B (metastatic tumors, 15) and group C (non-malignant lesions, 10). Ninety six permanent implants of 192Ir were inserted, with a low dose of 4-7 cGy/h and a total dose of 80-120 Gy. CONCLUSIONS: Stereotaxic biopsy is a very effective procedure with a significantly low range of complications. The permanent implant with a low dose rate, well situated and using a source of 192Ir is a safe, simple, effective method for the treatment of primary and recurrent glial tumours, and non-glial tumours which fulfil criteria for this type of brachytherapy.

Resección microquirúrgica estereotáxica de tumores intracraneales guiada por imagen y asistida por ordenador / Stereotaxic microsurgical resection of intracranial tumors guided by imaging and assisted by computer

Introducción. Las técnicas microquirúrgicas para la resección de lesiones intracraneales se limitan donde las referencias anatómicas no existen o no pueden utilizarse como guía para la disección de lesiones localizadas profundamente o en áreas elocuentes más superficiales. La guía estereotáxica guiada por imágenes ofrece una definición volumétrica y geométrica precisa de las lesiones intracraneales. Su aplicación en la resección de los tumores intracraneales presenta algunas particularidades por la propia condición biológica de los mismos, así como por su variada localización. Objetivos. La orientación espacial durante la microcirugía constituye un elemento indispensable. Demostramos esta aplicación de la cirugía estereotáxica en el Centro Internacional de Restauración Neurológica (CIREN) en La Habana, Cuba, desde mayo de 1994 a febrero de 1998, al describir la realización de 65 intervenciones microquirúrgicas en condiciones estereotáxicas a 62 pacientes portadores de tumores cerebrales intracraneales. Pacientes y métodos. El procedimiento se dividió en tres etapas: adquisición de la imagen, tomografía axial computadorizada y planificación quirúrgica, con sistema de planeamiento STASSIS y procedimientos microquirúrgicos, que incluyó los sistemas estereotáxicos: Leksell, Micromar y Estereoflex. Resultados. Del total, 27 de estos pacientes presentaron tumores gliales, 33 no gliales y sólo 2 lesiones no neoplásicas de localización y tamaño variados. Se realizaron 30 resecciones totales, la morbilidad quirúrgica fue mínima y no hubo mortalidad quirúrgica. Conclusiones. Las principales ventajas del método son: localización exacta de la craneotomía, fácil orientación espacial y facilidad para distinguir los límites entre el tumor y el tejido sano. Se demostró la aplicabilidad del Estereoflex a la microcirugía cerebral (AU)

Biopsia estereotáxica e implante de 192Ir en tumores intracraneales.Revisión de siete años de experiencia / Stereotaxic biopsy and implantation of 192Ir in intracranial tumors. A review of seven years experience

Introducción. La combinación de técnicas estereotáxicas, los avances en las neuroimágenes y la creación de programas informáticos cada vez más óptimos ha permitido la realización de biopsias estereotáxicas a lesiones cerebrales en las más variadas localizaciones. El perfeccionamiento del método de radiación intersticial permanente (braquiterapia) mejora la exactitud en la colocación de las fuentes radiactivas, liberando una dosis de radiación máxima al tumor con mínima irradiación del tejido normal que lo rodea. Pacientes y métodos. Fueron tratados 237 pacientes (de 1 a 78 años) con lesiones intracraneales, todos ellos incluidos en el protocolo de nuestra institución; se utilizaron los sistemas estereotáxicos de Leksell, Riechert-Mundinger, Micromar y Estereoflex. El procedimiento constó de tres etapas: adquisición de la imagen, planificación quirúrgica e intervención quirúrgica. La guía por imagen fue la tomografía axial computadorizada (TAC). Resultados. Se realizó biopsia estereotáxica guiada por imágenes de TAC a 153 pacientes, los cuales se dividieron en tres grupos tomando como referencia el hallazgo de la biopsia: grupo A (tumores primarios, 128); grupo B (tumores metastásicos, 15), y grupo C (lesiones no malignas, 10). Se realizaron 96 implantes permanentes de 192Ir con una tasa de dosis baja de 4-7 cGy/h con dosis total de 80 a 120 Gy. Conclusiones. La biopsia estereotáxica es un procedimiento muy eficaz con un margen de complicaciones significativamente bajo. El implante permanente de tasa de dosis baja, bien localizado y utilizando una fuente de 192Ir es un método simple, seguro y eficaz en el tratamiento de tumores gliales primarios y recurrentes, así como en otros no gliales que reúnan los criterios para dicha modalidad de braquiterapia (AU)