Theoretical Study of the Function of the IP3 Receptor/BK Channel Complex in a Single Neuron / Estudio Teórico de la Función del Complejo Receptor-IP3/Canales BK en Neurona Única

ABSTRACT Large conductance calcium-activated potassium (BK) channels carry out many functions in the central nervous system. These channels open in response to increased cytosolic calcium ([Ca2+]cyt) concentration. The influx of calcium ions to the cytosol can occur through voltage-gated calcium channels (VGCCs) on the plasma membrane and/ or through IP3 receptors (IP3-Rs) and ryanodine receptors (RyRs) on the endoplasmic reticulum membrane. The BK channel/IP3-R/RyR interaction has been widely reported in smooth muscle but scarcely investigated in relation to neurons. The aim of this study was to theoretically explore the function of the BK/IP3-R complex by means of a computational model of a neuron that replicates the interaction between the release of Ca2+ from the endoplasmic reticulum (through IP3-Rs) and the opening of the BK channels. The mathematical models are based on the Hodgkin-Huxley formalism and the Goldbeter model. These models were implemented on Visual Basic® and differential equations were solved numerically. Distinct conditions were contemplated for BK conductance and the efflux of endoplasmic Ca2+ to the cytosol. An abrupt rise in [Ca2+]cyt (≥ 5 μM) and short duration (spark) was found to activate BK channels and either pause or stop the action potential train.

RESUMEN Los canales de potasio activados por calcio de gran conductancia (canales BK) cumplen múltiples funciones en el sistema nervioso central. Estos canales se abren en respuesta al incremento de la concentración de calcio citosólico ([Ca2+]cyt). La entrada de Ca2+ puede ocurrir a través de canales de calcio dependientes de voltaje (VGCCs) localizados en la membrana plasmática y por eflujo de Ca2+ del retículo endoplásmico (ER) causado por 1,4,5-Trifosfato (IP3) o rianodina (RyR). La interacción BK/IP3/RyR ha sido ampliamente estudiada en músculo liso, pero escasamente en neuronas. El objetivo de este estudio fue explorar teóricamente la función del complejo BK/IP3-R mediante un modelo computacional de una neurona que replica la interacción entre la liberación de Ca2+ del retículo endoplásmico (a través de IP3-Rs) y la apertura de los canales BK. Los modelos matemáticos se basan en el formalismo de Hodgkin-Huxley y el modelo de Goldbeter. Estos modelos fueron implementados en Visual Basic® y las ecuaciones diferenciales fueron resueltas por métodos numéricos. Se contemplaron distintas condiciones para la conductancia del canal BK y la salida de Ca2+ endoplásmico al citosol. Los resultados muestran que un incremento abrupto de [Ca2+] cyt (≥ 5 μM) y de corta duración (spark) activa los canales BK y producen una pausa o detiene el tren de potenciales de acción.

FOTROCAN Delphi consensus statement regarding the prevention and treatment of cancer-associated thrombosis in areas of uncertainty and low quality of evidence.

INTRODUCTION: Decision-making in cancer-related venous thromboembolism (VTE) is often founded on scant lines of evidence and weak recommendations. The aim of this work is to evaluate the percentage of agreement surrounding a series of statements about complex, clinically relevant, and highly uncertain aspects to formulate explicit action guidelines. MATERIALS AND METHODS: Opinions were based on a structured questionnaire with appropriate scores and were agreed upon using a Delphi method. Questions were selected based on a list of recommendations with low evidence from the Spanish Society of Oncology Clinical Guideline for Thrombosis. The questionnaire was completed in two iterations by a multidisciplinary panel of experts in thrombosis. RESULTS: Of the 123 statements analyzed, the panel concurred on 22 (17%) and another 81 (65%) were agreed on by qualified majority, including important aspects of long-term and prolonged anticoagulation, major bleeding and rethrombosis management, treatment in special situations, catheter-related thrombosis and thromboprophylaxis. Among them, the panelists agreed the incidental events should be equated to symptomatic ones, long-term and extended use of full-dose low-molecular weight heparin, and concluded that the Khorana score is not sensitive enough to uphold an effective thromboprophylaxis strategy. CONCLUSION: Though the level of consensus varied depending on the scenario presented, overall, the iterative process achieved broad agreement as to the general treatment principles of cancer-associated VTE. Clinical validation of these statements in genuine practice conditions would be useful.

Desarrollo de un Simulador de los Experimentos Clásicos y Actualizados de Fijación de Voltaje de Hodgkin y Huxley / Developing a simulation program for classic and updated Hodgkin and Huxley's voltage clamp experiments

Resumen: Los estudios de Hodgkin y Huxley fueron el punto de partida de la generación de modelos matemáticos que explican, reproducen y predicen los resultados experimentales del comportamiento de los canales iónicos sensibles a voltaje del axón. Los altos costos de estos experimentos impiden su implementación en la práctica docente de licenciatura. Una alternativa didáctica son los experimentos virtuales mediante simuladores computacionales. En este trabajo se presenta el desarrollo de un simulador que reproduce paso a paso los experimentos clásicos de Hodgkin y Huxley sobre las conductancias de los canales dependientes de voltaje del axón gigante de calamar. El simulador fue desarrollado en lenguaje Visual Basic ver 5.0 para ambiente Wiindows® . Está formado de cuatro módulos: (1) simulación de corrientes iónicas; (2) experimentos clásicos de Hodgkin y Huxley; (3) versión actual del modelo; (4) potenciales de acción. Consta de pantallas de interfaz que permiten simular y calcular los valores de las variables relacionadas con la conductancia de los canales. El usuario puede realizar una cantidad ilimitada de experimentos virtuales que le facilitarán la comprensión del tema.

Abstract: Hodgkin and Huxley ́s works were the starting point to generating mathematical models for explain, reproduce the experimental results and predict the behavior of voltage-sensitive ion channels in the axon. The high costs of these experiments avoid its implementation in teaching degree. An educational alternative is virtual experiments using computer simulations. In this work the development of a simulator that reproduces step by step the classic experiments of Hodgkin and Huxley on the conductance of voltage-dependent channels in squid giant axon is presented. The simulator was developed in Visual Basic language, ver 5.0 for Windows environment. It consists of four modules: (1) ionic currents simulation; (2) classical Hodgkin and Huxley ́s experiments; (3) current version model; (4) action potentials. It comprises connecting interface screens that allow simulate and compute the values of the variables associated with the channel conductance. The user can perform an unlimited number of virtual experiments that will facilitate the understanding of the subject.

A prognostic score to identify low-risk outpatients with acute deep vein thrombosis in the upper extremity.

BACKGROUND: No studies have identified which patients with upper-extremity deep vein thrombosis (DVT) are at low risk for adverse events within the first week of therapy. METHODS: We used data from Registro Informatizado de la Enfermedad TromboEmbólica to explore in patients with upper-extremity DVT a prognostic score that correctly identified patients with lower limb DVT at low risk for pulmonary embolism, major bleeding, or death within the first week. RESULTS: As of December 2014, 1135 outpatients with upper-extremity DVT were recruited. Of these, 515 (45%) were treated at home. During the first week, three patients (0.26%) experienced pulmonary embolism, two (0.18%) had major bleeding, and four (0.35%) died. We assigned 1 point to patients with chronic heart failure, creatinine clearance levels 30-60 mL min(-1) , recent bleeding, abnormal platelet count, recent immobility, or cancer without metastases; 2 points to those with metastatic cancer; and 3 points to those with creatinine clearance levels < 30 mL min(-1) . Overall, 759 (67%) patients scored ≤ 1 point and were considered to be at low risk. The rate of the composite outcome within the first week was 0.26% (95% confidence interval [CI] 0.004-0.87) in patients at low risk and 1.86% (95% CI 0.81-3.68) in the remaining patients. C-statistics was 0.73 (95% CI 0.57-0.88). Net reclassification improvement was 22%, and integrated discrimination improvement was 0.0055. CONCLUSIONS: Using six easily available variables, we identified outpatients with upper-extremity DVT at low risk for adverse events within the first week. These data may help to safely treat more patients at home.

Manejo y administración de hemoderivados por personal de enfermería en un hospital de segundo nivel / Handling and management of blood-derived products by the nursing staff in a second level hospital

Introducción: El manejo y administración de hemoderivados es una actividad que realiza el personal de enfermería, por lo cual es de gran importancia tener presente que un uso inadecuado de éstos puede tener consecuencias graves en los pacientes, siendo fundamental el buen desempeño del personal de enfermería para la práctica segura. Objetivo: Evaluar el desempeño de enfermería en el manejo y administración de hemoderivados en un hospital de segundo nivel. Métodos: Estudio de diseño transversal. Se incluyeron enfermeras durante el 1º Enero al 30 junio del 2013. Se utilizó un instrumento validado que consta de 4 criterios con 27 ítems de respuestas dicotómicas para identificar el desempeño en el manejo y ministración de hemoderivados. La población fue dividida por categoría contractual. Análisis estadístico: prueba Chi-cuadrada y/ exacta de Fisher. Resultados: Se incluyeron un total de 110 observaciones a personal de enfermería que administró hemoderivados. Se obtuvo un índice de eficiencia global parcial (IEG) parcial a excelente de 64.5%. No se encontró asociación en el turno (p=0.16), servicio (p=0.31) y/o categoría contractual (p=0.25). Los porcentajes de excelente en el IEF fueron bajos (por turno: matutino y nocturno de 10 y 13 respectivamente, medicina interna y cirugía general 5 y 7%, y conforme a la categoría contractual, la enfermera general obtuvo en excelente sólo el 7.5%). Conclusiones: Nuestros resultados nos alertan para implantar programas de capacitación a enfermeras, para otorgar atención de calidad, disminuyendo los riesgos que comprometan la vida del paciente.

Introduction: Handling and managing blood-derived products is a nursing staff activity and thus, it is very important to keep in mind that an inadequate handling of these products can have serious consequences on patients. Therefore, a safe practice from the nursing staff is fundamental. Objective: To assess the nursing performance related to the handling and management of blood-derived products in a second level hospital. Methods: A transversal study design. Nurses were observed from January 1 to June 30, of 2013. A validated instrument with 27 dichotomy-items, and based on 4 criteria, to assess the handling and management of blood-derived products was used. The population was divided by contractual category. Statistical analysis: Chi square and/or Fisher exact test. Results: A total of 110 observations to the nursing staff handling and managing blood-derived products were included. An index of global efficiency (IGE) of partial to excellent of 64.5% was obtained. No associations were found with shift (p=.16), service (p=.31) and/or contractual category (p=.25). The percentages of excellent in the IEF were low (per shift: morning and night of 10 and 13 respectively; per service: internal medicine and general surgery 5 and 7%, and according to the contractual category, overall excellent nurse obtained only 7.5%). Conclusions: Our results encourage us to foster training programs for nurses in order to enhance the quality of care and also decrease the life risks on the patients.

Evaluation of the antimutagenic activity and mode of action of the fructooligosaccharide inulin in the meristematic cells of Allium cepa culture.

This study evaluated the mutagenicity and antimutagenicity of inulin in a chromosomal aberration assay in cultures of the meristematic cells of Allium cepa. The treatments evaluated were as follows: negative control--seed germination in distilled water; positive control--aqueous solution of methyl methanesulfonate (10 µg/mL MMS); mutagenicity--aqueous solutions of inulin (0.015, 0.15, and 1.50 µg/mL); and antimutagenicity--associations between MMS and the different inulin concentrations. The antimutagenicity protocols established were pre-treatment, simultaneous simple, simultaneous with pre-incubation, and post-treatment. The damage reduction percentage (DR%) was 43.56, 27.77, and 55.92% for the pre-treatment; -31.11, 18.51, and 7.03% for the simultaneous simple; 30.43, 19.12, and 21.11% for the simultaneous with pre-incubation; and 64.07, 42.96, and 53.70% for the post-treatment. The results indicated that the most effective treatment for inhibiting damages caused by MMS was the post-treatment, which was followed by the pre-treatment, suggesting activity by bioantimutagenesis and desmutagenesis. The Allium cepa assay was demonstrated to be a good screening test for this type of activity because it is easy to perform, has a low cost, and shows DR% that is comparable to that reported studies that evaluated the prevention of DNA damage in mammals by inulin.

Pre-treatment with glutamine reduces genetic damage due to cancer treatment with cisplatin.

Cisplatin is an effective antineoplastic drug. However, it provokes considerable collateral effects, including genotoxic and clastogenic activity. It has been reported that a diet rich in glutamine can help inhibit such collateral effects. We evaluated this activity in 40 Swiss mice, distributed into eight experimental groups: G1 - Control group (PBS 0.1 mL/10 g body weight); G2 - cisplatin group (cisplatin 6 mg/kg intraperitoneally); G3, G4, G5 - glutamine groups (glutamine at 150, 300, and 600 mg/kg, respectively; orally); G6, G7, G8 - Pre-treatment groups (glutamine at 150, 300, and 600 mg/kg, respectively; orally and cisplatin 6 mg/kg intraperitonially). For the micronucleus assay, samples of blood were collected (before the first use of the drugs at T0, then 24 (T1) and 48 (T2) hours after the first administration). For the comet assay, blood samples were collected only at T2. The damage reduction percentages for the micronucleus assay were 90.0, 47.3, and 37.3% at T1 and 46.0, 38.6, and 34.7% at T2, for G6, G7, and G8 groups, respectively. For the comet assay, the damage reduction percentages were 113.0, 117.4, and 115.0% for G6, G7, and G8, respectively. We conclude that glutamine is able to prevent genotoxic and clastogenic damages caused by cisplatin.

Evaluation of the antimutagenic and anticarcinogenic effects of inulin in vivo.

The incidence of colorectal cancer is growing worldwide. The characterization of compounds present in the human diet that can prevent the occurrence of colorectal tumors is vital. The oligosaccharide inulin is such a compound. The aim of this study was to evaluate the antigenotoxic, antimutagenic and anticarcinogenic effects of inulin in vivo. Our study is based on 3 assays that are widely used to evaluate chemoprevention (comet assay, micronucleus assay, and aberrant crypt focus assay) and tests 4 protocols of treatment with inulin (pre-treatment, simultaneous, post-treatment, and pre + continuous). Experiments were carried out in Swiss male mice of reproductive age. In order to induce DNA damage, we used the pro-carcinogenic agent 1,2-dimethylhydrazine. Inulin was administered orally at a concentration of 50 mg/kg body weight following the protocols mentioned above. Inulin was not administered to the control groups. Our data from the micronucleus assay reveal antimutagenic effects of inulin in all protocols. The percentage of inulin-induced damage reduction ranged from 47.25 to 141.75% across protocols. These data suggest that inulin could act through desmutagenic and bio-antimutagenic mechanisms. The anticarcinogenic activity (aberrant crypt focus assay) of inulin was observed in all protocols and the percentages of damage reduction ranged from 55.78 to 87.56% across protocols. Further tests, including human trials, will be necessary before this functional food can be proven to be effective in the prevention and treatment of colon cancer.

Body mass index and mortality in patients with acute venous thromboembolism: findings from the RIETE registry.

BACKGROUND: There is little information on the influence of body mass index (BMI) on mortality in patients with acute venous thromboembolism (VTE). PATIENTS AND METHODS: RIETE is an ongoing registry of consecutive patients with symptomatic, objectively confirmed, acute VTE. We examined the association between BMI and mortality during the first 3 months of therapy. RESULTS: Of the 10 114 patients enrolled as of March 2007: 153 (1.5%) were underweight (BMI < 18.5); 2882 (28%) had a normal weight (BMI 18.5-24.9); 4327 (43%) were overweight (BMI 25.0-30); and 2752 (27%) were obese (BMI > 30). The overweight and obese patients were significantly older, and were less likely to have had cancer, recent immobility or renal insufficiency. After 3 months of therapy their death rates were 28%, 12%, 6.2% and 4.2%, respectively. In multivariate analysis, the relative risks for death after adjusting for confounding variables including age, cancer, renal insufficiency or idiopathic VTE were: 2.1 (95% CI, 1.5-2.7); 1.0 (reference); 0.6 (95% CI, 0.5-0.7); and 0.5 (95% CI, 0.4-0.6), respectively. The rates of fatal pulmonary embolism (2.0%, 2.1%, 1.2% and 0.8%, respectively) also decreased with BMI. There were no differences in the rate of fatal bleeding, but patients who were underweight had an increased incidence of major bleeding complications (7.2% vs. 2.7%; odds ratio, 2.7; 95% CI, 1.4-5.1). CONCLUSIONS: Obese patients with acute VTE have less than half the mortality rate when compared with normal BMI patients. This reduction in mortality rates was consistent among all subgroups and persisted after multivariate adjustment.

[Health care at home setting: social interaction and daily life]. / El cuidado a la salud en el ámbito doméstico: interacción social y vida cotidiana.

OBJECTIVE: To explore the boundaries and agents which make up women's knowledge about health care. METHODS: A qualitative study was carried out in 4 regions in Mexico. Forty middle-aged women (between 35 and 65 years old) were interviewed and their responses analyzed. RESULTS: The findings of this study point out to the relationship of women and their different social interactions with their health care practice. Among these interactions are: the contact with health services (which shapes the way women take care of their own health and their family); mass media (particularly television); use of medicines; traditional healers; knowledge acquired from their grandparents, mothers, and peers; and women's own experience while taking care of their family. Health care at home setting is a mixture of traditional healing practices and the conventional medical practices disseminated among the population. CONCLUSION: The different social interactions in which women are involved make up the way Mexican women take care of their own health and their family.

Fine needle aspiration for flow cytometry immunophenotyping of non Hodgkin lymphoma.

The aim was to evaluate the usefulness of lymph node biopsies obtained by fine needle aspiration (FNA) for immunophenotyping of non Hodgkin lymphoma (NHL). Seventeen superficial and deep lymph node samples were fractioned for conventional cytological examination and immunophenotyping studies. Out of ten NHL, nine were readily detected by flow cytometry (FC), while failure on the remaining case was due to selective loss of large cell population, which is liable to occur with this procedure. A single case, which proved negative for all markers employed, was finally diagnosed by immunohistochemistry as germ cell tumor. The other six cases, presenting lymphoid population without phenotypic abnormalities, were diagnosed by cytology and/or histology as Hodgkin disease or hyperplasic disorders. To conclude, FC immunophenotyping seems to improve the efficacy of FNA in NHL diagnosis, whereas for Hodgkin disease and hyperplasic disorders, classic morphological criteria are more useful for differential diagnosis. Although FNA for FC immunophenotyping cannot replace histopathological examination for NHL diagnosis, it proves to be a useful tool for staging and follow up, making surgical procedures for sample collection unnecessary.

Fine needle aspiration for flow cytometry immunophenotyping of non Hodgkin lymphoma.

The aim was to evaluate the usefulness of lymph node biopsies obtained by fine needle aspiration (FNA) for immunophenotyping of non Hodgkin lymphoma (NHL). Seventeen superficial and deep lymph node samples were fractioned for conventional cytological examination and immunophenotyping studies. Out of ten NHL, nine were readily detected by flow cytometry (FC), while failure on the remaining case was due to selective loss of large cell population, which is liable to occur with this procedure. A single case, which proved negative for all markers employed, was finally diagnosed by immunohistochemistry as germ cell tumor. The other six cases, presenting lymphoid population without phenotypic abnormalities, were diagnosed by cytology and/or histology as Hodgkin disease or hyperplasic disorders. To conclude, FC immunophenotyping seems to improve the efficacy of FNA in NHL diagnosis, whereas for Hodgkin disease and hyperplasic disorders, classic morphological criteria are more useful for differential diagnosis. Although FNA for FC immunophenotyping cannot replace histopathological examination for NHL diagnosis, it proves to be a useful tool for staging and follow up, making surgical procedures for sample collection unnecessary.