Ca2+ /H+ exchange via the plasma membrane Ca2+ ATPase in skeletal muscle.

The aims of this work were to determine: 1) whether Ca2+ exit via the plasmalemmal Ca2+ ATPase (PMCA) is coupled to H+ entry via a Ca2+/H+ exchange; 2) whether operation of PMCA has an absolute requirement on external H+ (Ho); and 3) the stoichiometry and voltage-dependence of the Ca2+/H+ exchange. Barnacle muscle cells were used because of the ease with which they can be internally-perfused (e.g., with 45Ca), voltage-clamped and impaled with a pH electrode. Thus, the simultaneous measurement of plasmalemmal Ca2+ and H+ fluxes can be measured. The effects of Ho, intracellular ATP, PMCA blockers, and membrane potential (VM) were studied on PMCA-mediated Ca2+/H+ exchange. The results indicate that: i) Ca2+ efflux is promoted by external acidification, is accompanied by a membrane depolarization, and by an intracellular acidification greater than the one resulting from Ho "leak" and PMCA-mediated ATP hydrolysis; ii) Ho-dependent Ca2+ efflux is inhibited by PMCA blockers and by ATP depletion and is accelerated by membrane depolarization (~3 fold by 20 mV depolarization); iii) the coupling ratio of the Ca2+/H+ exchange depends on Ho: at an extracellular pH (pHo)=6.5, the ratio is 1Ca2+:~3H+; at pHo=8.2, Ca2+ efflux rate is 3 times slower and the ratio is 1Ca2+: <1H+.

Cáncer y COVID-19, un vínculo peligroso / Cancer and COVID-19, a dangerous association

Fundamento: La COVID-19 es una pandemia causada por el virus SARS-CoV-2 cuya asociación con el cáncer puede tener efectos adversos.Objetivo: Describir los principales vínculos entre el cáncer y la COVID-19.Metodología: Se realizó una búsqueda bibliográfica en Google Académico, SciELO y PubMed Central con los descriptores SARS-CoV-2, COVID-19 y cáncer, consultados en el DeCS. Se seleccionaron artículos a texto completo en español e inglés, principalmente de revistas arbitradas por pares.Resultados: La COVID-19 produce resultados más desfavorables en los pacientes con cáncer. Estos resultados se relacionan con altas tasas de hospitalización, complicaciones y mortalidad. La frecuente asociación decomorbilidades en pacientes con cáncer parece contribuir a este vínculo peligroso. Las vías de señalización comunes al cáncer y a la infección por el SARS-CoV-2 son citocinas proinflamatorias, interferón tipo I, receptorde andrógenos y puntos de control inmune. Este conocimiento tiene aplicación práctica en el empleo de medicamentos para combatir la COVID-19 en pacientes con cáncer.Conclusiones: El cáncer se relaciona con la COVID-19 grave, por lo que esos pacientes son más vulnerables a la infección viral.[AU]

Prostaglandin modulation of N-formylmethionylleucylphenylalanine-induced transmembrane potential changes in rat neutrophils.

Prostaglandins of the E-series (PGEs) and PGI2 will inhibit formylmethionylleucylphenylalanine-(f-Met-Leu-Phe) induced lysosomal enzyme release and superoxide-anion (O2-) production by neutrophils. The inhibitory effects of PGEs and PGI2 on neutrophil functional responses have been correlated with their ability to increase intracellular cAMP. In this study we have examined the effects of PGEs and PGI2 on f-Met-Leu-Phe- and phorbol-myristate-acetate-induced rat neutrophil membrane potential changes using an optical probe of membrane potential 3,3-dipropylthiodicarbocyanine iodide. 15-(S)-15-methyl-PGE1 (15-methyl-PGE1), a stable analogue of PGE1 and PGI2 inhibited f-Met-Leu-Phe-induced transmembrane potential changes in a dose-dependent manner. This inhibition was correlated with the ability of these agents to increase intracellular cAMP levels and inhibit O2- production and degranulation. In contrast, 15-methyl-PGE1 and PGI2, did not inhibit phorbol-myristate-acetate-induced transmembrane potential changes and O2- production. These results suggest independent mechanisms of activation of neutrophils by phorbol myristate acetate and f-Met-Leu-Phe, and they also suggest that the inhibitory effects of prostaglandins and cAMP on f-Met-Leu-Phe-stimulated cells is at a step or steps prior to activation of those processes involved in effecting changes in transmembrane potential, which are common to both stimuli.

3-deaza-adenosine inhibition of stimulus-response coupling in human polymorphonuclear leukocytes.

In an effort to define better the functional role of S-adenosyl-methionine-mediated methylation reactions in modulating polymorphonuclear (PMN) functional responses to chemotactic stimuli, we investigated the effects of 3-deaza-adenosine (3-DZA), a known inhibitor of methylation reactions in phagocytic cells, on formyl methionyl-leucyl-phenylalanine (FMLP)-induced responses in human PMN leukocytes. Using the fluorescent cyanine dye 3,3'-dipropylthiocarbocyanine (di-S-C3-(5)) as an optical probe of membrane potential we observed that 3-DZA at concentrations that inhibit FMLP-induced O2- production does not significantly alter FMLP-induced changes in transmembrane potential. Additional studies showed an inhibitory effect of 3-DZA on FMLP-induced PMN pinocytosis and to a lesser degree on FMLP-induced degranulation. However, pretreatment of PMNs with 3-DZA did not alter FMLP-induced changes in Quin-2 fluorescence, an indicator of changes in intracellular calcium levels. These findings demonstrate a dissociation between chemotactic factor-induced cell membrane depolarization, changes in intracellular calcium, and specific neutrophil functional responses and suggest that chemotactic factor-induced changes in transmembrane potential and intracellular calcium are independent of chemotactic factor-induced methylation reactions. Furthermore, 3-DZA did not alter phorbol myristate acetate induced O2- production or fluid pinocytosis indicating a stimulus specificity for the inhibitory effects of this agent on O2- production.

Association between Whipple's disease and Giardia lamblia infection.

Whipple' disease is mainly characterized by affecting the digestive system, although it can be a multisystemic process with different clinical symptoms. The bacillus causing the disease has been isolated and cultivated in 2000 and the genome sequence has been recently analyzed in 2003, which means new perspectives for its diagnosis and treatment. Giardiasis is an infestation caused by a protozoo and may cause a malabsorption syndrome or run in a subclinic way. The case of a middle-aged male is described, who after a three-year period of migratory arthralgias, showed weight loss, diarrheas and abdominal pain, being diagnosed of Giardiasis, and after the persistent symptoms and a number of studies, was diagnosed with Whipple disease. Nineteen cases of Giardia-Whipple coinfection have been described in the literature, but the reason of this association has not been found yet. The discussion on whether there is an alteration in the immunitary system which facilitates infections or, the development of an infection lead to the other one, goes on.

Profesor Hein J. J. Wellens (Henrick Joan Joost Wellens), 1935-2020 / Professor HeinJ.J.Wellens (HenrickJoanJoostWellens), 1935-2020

Hein J. J. Wellens, profesor de profesores, mi mentor en el área de electrofisiología y cardiología, ha muerto, pero ha dejado un legado muy importante para Colombia. Tuve el honor de ser uno de los pioneros de la electrofisiología en Colombia, y, además, su primer alumno colombiano. Recuerdo que el 1.° de julio de 1988 me presenté en su oficina en el Hospital Universitario de Limburg (Maastricht). Me saludó cariñosamente y me dijo que era un honor para él formar al primer alumno colombiano y que yo asumía, a partir de ese momento, un reto muy grande para desarrollar la electrofisiología en el país. Volviendo un poco atrás en la historia, cuando le hice la petición de ingreso (en ese momento no existía como tal la subespecialización de electrofisiología en el mundo), me respondió que ya tenía los fellows listos para los años 88 y 89, pero que si me podía recibir antes lo haría, pues quería formar algún electrofisiólogo de Colombia. Días después recibí su comunicación de que me esperaba en el servicio, puesto que uno de los fellows que iba a Maastricht había cancelado su viaje; por tanto, empaqué maletas y allí llegué. Él personalmente me llevó hasta la oficina de su jefe de electrofisiología, que era el Profesor Pedro Brugada. Luego me presentó a cada uno de los fellows que serían mis compañeros de entrenamiento, entre ellos estaban Josep Brugada, Jacob Atié, Louis Mont, Luz María Morales (+), entre otros. Estos dos monstruos de la electrofisiología fueron, junto con el doctor Joep Smeets, mis profesores.

Inhibition of neutrophil activation by p-bromophenacyl bromide and its effects on phospholipase A2.

In an effort to elucidate the nature of the inhibitory effects of p-bromophenacyl bromide (pBPB) on neutrophil stimulation, we have examined its effects on several stages of stimulus-response coupling. Pretreatment of rat neutrophils with pBPB resulted in a dose- and time-dependent irreversible inhibition of both N-formylmethionyl-leucylphenylalanine (fMet-Leu-Phe)-induced lysosomal enzyme release and change in transmembrane potential. Inhibition of the biological responses to the chemotactic peptide fMet-Leu-Phe was not due to receptor inactivation since fMet-Leu-[3H]-Phe binding to the formyl peptide receptor was not significantly altered by pBPB pretreatment. Inhibition by pBPB of phorbol myristate acetate (PMA)-induced changes in transmembrane potential and the generation of superoxide (0-2) was also observed. pBPB treatment appeared to inhibit activation of the NADPH oxidase without a direct effect on the oxidase itself. This inhibitory effect was not accompanied by cell death or decrease in cellular titratable sulphydryl groups (at least at doses less than 20 microM). There was, however, significant inhibition of a membranous fraction of fMet-Leu-Phe-induced phospholipase A2 activity by pretreatment with 10 microM pBPB, although total cellular phospholipase A2 was only minimally (less than 20% inhibition) affected. These data would indicate that pBPB inhibits an early event associated with stimulus-response coupling in rat polymorphonuclear leukocytes (i.e. change in transmembrane potential). The inhibitory effects of pBPB may be secondary to the inhibition of a critical membranous fraction of cell bound phospholipase A2 activity or its activation, necessary for the initiation of cell activation.

Site-dependent phenotypic heterogeneity in peripheral T-cell lymphoma.

Peripheral T-cell lymphomas constitute a heterogeneous population of postthymic T-cell malignancies. Characteristically, they present a varied phenotypic expression, which can be helpful in establishing the diagnosis. A case of a peripheral T-cell lymphoma in a 76-year-old man is described. The malignant cells in the skin and bone marrow were of the T4 (helper/inducer) phenotype, yet they did not express pan-T-cell antigens, such as T11, or functional E rosettes. In a biopsy specimen from a lymph node, however, the malignant cells had a helper/inducer phenotype and also expressed the pan-T-cell antigens T11 and Leu-5. Additionally, the malignant cells from the lymph node formed E rosettes. This study demonstrates the phenotypic heterogeneity of malignant T cells, which appears to be site-dependent.

Immunophenotypic characterization of an unusual T-cell lymphoma presenting as anterior uveitis. A clinicopathologic case report.

A 54-year-old woman presented with a unilateral, anterior uveitis that progressed to hypopyon over 4 months despite treatment with steroids. One hundred percent of the cells collected from aspirates of the anterior chamber of the affected eye were morphologically large granular lymphocytes. The aspirated cells were demonstrated by flow cytometry to be a uniform population of T lymphocytes with a diploid genome and an S fraction of 2.3%. On further investigation, the patient was found to have an extensive abdominal malignant lymphoma with the same immunophenotype but different morphologic features than the anterior chamber lymphoid infiltrate. In contrast to the cells in the anterior chamber, the abdominal tumor was highly aggressive as indicated by the cellular morphologic features and the S fraction of 43%. DNA hybridization studies of the abdominal lymphoma demonstrated a T beta 2 T-cell receptor gene rearrangement. The use of these modern diagnostic methods should facilitate the diagnosis of intraocular lymphomas and may have important therapeutic and prognostic implications in the future.

Flow cytometric analysis of lymphomas and acute leukemias.

In summary, flow cytometry is highly applicable to the detection and classification of leukemias and lymphomas due to the ease with which single-cell suspensions may be made. Composite immunophenotypic analysis is essential for classifying leukemias once the disease is detected by traditional means. In contrast, in the detection of lymphoproliferative diseases, the composite immunophenotype is itself diagnostic of the disease process. Characterization of size, as measured by light scatter and by DNA ploidy and cell cycle analysis, contributes to the further subdivision of lymphoproliferative disorders. Specifically, small, monoclonal cells that are diploid with a synthetic fraction of 5% are characteristic of low-grade lymphomas. Admixtures of large and small cells wherein the large cells are monoclonal and the small cells are either monoclonal or heterogeneous may be seen in intermediate lymphomas. In this category, DNA ploidy is variable and the total synthetic fraction is usually between 5% and 15%. High-grade lymphomas, with the exception of the immunoblastic category, are usually of intermediate size, are diploid or near-diploid, and exhibit synthetic fractions greater than 15%. Interestingly, few reactive T cells are seen. Ongoing efforts to standardize procedures will eventually result in more widespread applicability together with improved understanding of the attributes and limitations of this technology. The most important consideration, however, is that the technology is useless in the absence of a working knowledge of the biology of the diseases to be characterized. Conversely, the complexity of flow cytometry is sufficient to warrant rigorous training of laboratory professionals in this field.

Biclonal composite lymphoma. A multiparameter flow cytometric analysis.

A case of composite, biclonal lymphoma detected and characterized by multiparameter flow cytometric analysis is presented. Analysis of cell surface immunophenotype and cell size, as assessed by forward light scatter, revealed that two populations of cells were present. The small cells were monoclonal kappa-positive cells admixed with reactive T and B cells. The large cells reacted solely with anti-lambda antibodies. Dual-color and dual-parameter (surface vs DNA) analysis further showed that the small, kappa-positive cells coexpressed CD5 and were diploid, with an estimated synthetic (S) fraction of 2.2%. The predicted histologic pattern was malignant lymphoma, small lymphocytic. In contrast, the large lambda-positive cells were both hyperdiploid and tetraploid with an estimated S fraction of 18%. On the basis of this multiparametric analysis, the predicted histologic pattern for the latter component was malignant lymphoma, diffuse large-cell type. Subsequent histologic examination confirmed the predicted pattern in both cases.

Peripheral polyneuropathy complicating conditions of sepsis and multi-organ failure.

We studied five patients who developed evidence of acute mainly motor peripheral polyneuropathy complicating a condition of prolonged sepsis associated with multi-organ failure. In the electrophysiological studies we observed normal motor and sensory nerve conduction velocities but there were drops in the amplitudes of the compound action potentials in the muscles and sensory peripheral nerves as well as high denervation activity on electromyography. Analytical studies of cerebrospinal fluid and blood did not show any findings of interest except for a deterioration in the nutritional parameters without specific deficiencies. The immunological and microbiological studies failed to determine factors related to the development of polyneuropathies. Nerve and muscle biopsies showed axonal neuropathy with some demyelination changes and reinnervation. Three patients survived the critical state and were re-examined presenting a moderate improvement in the neurological condition accompanied with signs of reinnervation in the electromyographic study. Given the absence of known factors implicated in the development of acute polyneuropathies in our patients, we suggest that the relevant disorders of the cellular metabolism observed in patients with prolonged sepsis aggravated by the defective nutritional condition, may be factors related to the development of these polyneuropathies.

[1st Latin American consensus conference on immunologic typing of leukemias]. / Primera conferencia latinoamericana de consenso en la tipificación inmunológica de leucemias.

On October 16, 1996, the first Latinamerican Consensus Conference for the Immunophenotyping of Leukemia took place in the City of Puebla, Mexico, with representatives from ten countries of the region, and two external consultants. This document summarizes the major conclusions where scientific consensus was achieved.

[Dyggve-Melchior-Clausen syndrome, diagnostic difficulty due to it similarity to Morquio disease]. / Síndrome de Dyggve-Melchior-Clausen, dificultad en su diagnóstico por similitud con la enfermedad de Morquio.

INTRODUCTION: Dyggve-Melchior-Clausen syndrome (DMCS) is a rare autosomal recessive disorder produced by mutations in the Dymeclin gene recently identified. It is characterized by the association of a progressive spondylo-epi-metaphyseal dysplasia and mental retardation ranging from mild to severe. The clinical and radiological similarities at the onset of the condition with the Morquio disease may hinder its diagnosis and no biochemical abnormality that causes it has been described as of yet. CLINICAL CASE: An eight-year-old girl had progressive postnatal dwarfism. Platyspondyly and dysplasic epiphyses and metaphyses with biochemical studies that resembled those of Morquio's disease; however the presence of specific radiological features and mental retardation led to the diagnosis of DMCS. A missense Dym mutation in homozygosis was identified. CONCLUSION: This entity should be known as it may be easily confused with Morquio disease. Radiological appearance of the iliac crests are very pathognomonic of DMCS. Identification of Dym gene is an important step towards the prenatal diagnosis.

Tratamiento perioperatorio del paciente con antiagregación o anticoagulación / Peri-operative management of patients with anti-platelet or anticoagulation treatment

El tratamiento del paciente que recibe terapias que afectan la hemostasia normal (anticoagulantes y/o antiagregantes plaquetarios) y que será sometido a un procedimiento quirúrgico, es uno de los retos que se presentan cada vez con mayor frecuencia en los servicios de cardiología. La toma de la mejor opción terapéutica en este grupo de pacientes requiere un profundo conocimiento sobre los riesgos de sangrado en caso de continuarse el tratamiento, frente a los riesgos de trombosis o embolismo en caso de suspenderlo. Por tradición, esa decisión se ha basado más en el temor al riesgo de sangrado, por lo cual en muchos casos se ha suspendido dicha terapia de manera innecesaria. En los últimos años, la aparición de la evidencia que indica que no sólo no es alto el riesgo de sangrado sino que además la continuación de estos medicamentos en muchos casos disminuye desenlaces adversos mayores, ha llevado a replantear esta conducta. En este artículo se revisará la evidencia actual existente al respecto y se suministrarán pautas que permitan la toma de una decisión adecuada.

Treatment of patients receiving therapies that affect normal hemostasis (anticoagulants and / or anti-platelet aggregators) and that will undergo surgery, is one of the challenges that arise with increasing frequency in the cardiology services. Making the best therapeutic option in these patients requires a thorough understanding of the risks of bleeding in case of continuing the treatment against the risks of thrombosis or embolism in case of stopping it. By tradition, this decision has been based more on fear to the risk of bleeding, whereby in many cases this therapy has been suspended unnecessarily. In recent years, the emergence of evidence indicates that the risk of bleeding is not high and that continuation of these drugs in many cases reduce major adverse outcomes. This has led to redefine this behavior. In this article we review the current evidence available on the subject and provide guidelines that allow making a right decision.

Síndrome de QT prolongado congénito y embarazo: reporte de dos casos / Congenital long QT syndrome and pregnancy: report of two cases

El síndrome de QT prolongado congénito, es una entidad clínica que se caracteriza por la alteración en la repolarización miocárdica dada por una prolongación significativa del intervalo QT con riesgo aumentado de síncope, taquicardia ventricular polimórfica y muerte súbita. Se produce por la alteración en la función de canales iónicos responsables del potencial de acción de las células cardíacas, como consecuencia de múltiples mutaciones, de las cuales las más frecuentes se dan en los canales de sodio y potasio. La relación con el embarazo y principalmente la presencia de eventos en el posparto, está determinada por arritmias ventriculares o episodios de muerte súbita, lo cual debe llevar a una evaluación exhaustiva de QTc prolongado y sus factores desencadenantes o enfermedades concomitantes. Se muestran los casos clínicos de dos pacientes que presentaron muerte súbita en el posparto en las cuales se diagnosticó síndrome de QT largo congénito.

Congenital long QT syndrome is a clinical entity characterized by impairment of myocardial repolarization given by significant prolongation of the corrected QT interval with an increased risk of syncope, polymorphic ventricular tachycardia and sudden death. This is produced by an alteration in the function of ion channels responsible for the action potential of cardiac cells as a consequence of multiple mutations, the most common of which are in the sodium and potassium channels. The relationship with pregnancy and especially the presence of events in the postpartum period is clearly determined by the presence of ventricular arrhythmias or episodes of sudden death, that should lead to a thorough evaluation of prolonged QTc and its triggers or concomitant diseases. We present the clinical records of two patients who had sudden death during the postpartum and were diagnosed as congenital long QT Syndrome.

The macrophage adherence phenomenon: its relationship to prostaglandin E2 and superoxide anion production and changes in transmembrane potential.

Mononuclear phagocytes are undoubtedly the sine qua non of chronic inflammatory reactions. This is demonstrated by their unique ability to function as phagocytic, secretory, or effector cells during the course of an immune event. Although macrophages can perform a variety of immune tasks, their ability to function appropriately is dependent upon the mode of elicitation, the stimulus under investigation, the source of the macrophages (peritoneal, alveolar, etc.), and whether the macrophages are monolayers or in suspension. We have examined the relationship between adherent and non-adherent elicited peritoneal macrophages in terms of prostaglandin E2 (PGE2) and superoxide anion (O2-) production; in addition, we have studied these elicited macrophages in suspension for their ability to undergo transmembrane potential changes in response to several stimuli. Non-adherent, elicited peritoneal macrophages demonstrated an increase in basal PGE2 production, and were refractory to particulate stimulus. After monolayer formation, basal PGE2 levels dropped and the cells could respond to both soluble and particulate stimuli. Only adherent macrophages could respond to a specific challenge and synthesize O2-. Both O2- production and depolarization of the transmembrane potential were suppressed in cells in suspension. Furthermore, both exogenous PGE2 and supernatant from macrophages in suspension could modulate O2- production by PMA challenged macrophages monolayers. These studies indicate that PGE2 may modulate macrophage function and dictate activity as macrophages go from the non-adherent to adherent state.

Quantitative assessment of neutrophil function by flow cytometry.

The use of flow cytometry (FCM) to quantitatively assess neutrophil function is reviewed. The methodology is capable of measuring a number of parameters involved in the oxidative pathways that form the basis of the activated neutrophil's contribution to the host defense mechanism. These events are summarized and some findings, such as in patients with chronic granulomatous disease, are discussed. FCM study of neutrophil function requires smaller numbers of cells than do traditional methods, which makes it particularly useful in the assessment of small fluid samples or in the evaluation of multiple parameters, and has the advantage that cell purification procedures are not essential.