Summary of recommendations and key points of the consensus of Spanish scientific societies (SEPAR, SEMICYUC, SEMES; SECIP, SENEO, SEDAR, SENP) on the use of non-invasive ventilation and high-flow oxygen therapy with nasal cannulas in adult, pediatric, and neonatal patients with severe acute respiratory failure.

Non-invasive respiratory support (NIRS) in adult, pediatric, and neonatal patients with acute respiratory failure (ARF) comprises two treatment modalities, non-invasive mechanical ventilation (NIMV) and high-flow nasal cannula (HFNC) therapy. However, experts from different specialties disagree on the benefit of these techniques in different clinical settings. The objective of this consensus was to develop a series of good clinical practice recommendations for the application of non-invasive support in patients with ARF, endorsed by all scientific societies involved in the management of adult and pediatric/neonatal patients with ARF. To this end, the different societies involved were contacted, and they in turn appointed a group of 26 professionals with sufficient experience in the use of these techniques. Three face-to-face meetings were held to agree on recommendations (up to a total of 71) based on a literature review and the latest evidence associated with 3 categories: indications, monitoring and follow-up of NIRS. Finally, the experts from each scientific society involved voted telematically on each of the recommendations. To classify the degree of agreement, an analogue classification system was chosen that was easy and intuitive to use and that clearly stated whether the each NIRS intervention should be applied, could be applied, or should not be applied.

Summary of recommendations and key points of the consensus of Spanish scientific societies (SEPAR, SEMICYUC, SEMES; SECIP, SENEO, SEDAR, SENP) on the use of non-invasive ventilation and high-flow oxygen therapy with nasal cannulas in adult, pediatric, and neonatal patients with severe acute respiratory failure. / Sumario de las recomendaciones y puntos clave del Consenso de las Sociedades Científicas Españolas (SEPAR, SEMICYUC, SEMES; SECIP, SENeo, SEDAR, SENP) para la utilización de la ventilación no invasiva y terapia de alto flujo con cánulas nasales en el paciente adulto, pediátrico y neonatal con insuficiencia respiratoria aguda grave.

Non-invasive respiratory support (NIRS) in adult, pediatric, and neonatal patients with acute respiratory failure (ARF) comprises two treatment modalities, non-invasive mechanical ventilation (NIMV) and high-flow nasal cannula (HFNC) therapy. However, experts from different specialties disagree on the benefit of these techniques in different clinical settings. The objective of this consensus was to develop a series of good clinical practice recommendations for the application of non-invasive support in patients with ARF, endorsed by all scientific societies involved in the management of adult and pediatric/neonatal patients with ARF. To this end, the different societies involved were contacted, and they in turn appointed a group of 26 professionals with sufficient experience in the use of these techniques. Three face-to-face meetings were held to agree on recommendations (up to a total of 71) based on a literature review and the latest evidence associated with 3 categories: indications, monitoring and follow-up of NIRS. Finally, the experts from each scientific society involved voted telematically on each of the recommendations. To classify the degree of agreement, an analogue classification system was chosen that was easy and intuitive to use and that clearly stated whether the each NIRS intervention should be applied, could be applied, or should not be applied.

Ventilación mecánica domiciliaria en niños: estudio multicéntrico español / Domiciliary mechanical ventilation in children: a spanish multicentre study

Introducción: La ventilación mecánica domiciliaria (VMD) es una técnica cada vez más frecuente en el niño. Existen pocos estudios que hayan analizado las características y necesidades de los niños sometidos a esta técnica. Material y métodos: Estudio descriptivo observacional transversal multicéntrico de pacientes entre un mes y 16 años dependientes de ventilación mecánica domiciliaria. Resultados: Se estudiaron 163 pacientes de 17 hospitales españoles con una edad media de 7,6 años. La causa más frecuente de VMD fueron los trastornos neuromusculares. El inicio de la VMD fue a una edad media de 4,6 años. Un 71,3% recibieron ventilación no invasiva. Los pacientes con ventilación invasiva tenían menor edad, menor edad de inicio de la VMD y mayor tiempo de uso diario. El 80,9% precisaban VM solo durante el sueño, y un 11,7% durante todo el día. Únicamente un 3,4% de los pacientes tiene asistencia sanitaria externa como ayuda a la familia. Un 48,2% es controlado en consultas específicas de VMD o consultas multidisciplinares. Un 72,1% de los pacientes está escolarizado (recibiendo enseñanza adaptada un 42,3%). Solo un 47,8% de los pacientes escolarizados cuentan con cuidadores específicos en su centro escolar. Conclusiones: La VMD en niños se utiliza en un grupo muy heterogéneo de pacientes iniciándose en un importante porcentaje en los primeros 3 años de vida. A pesar de que un significativo porcentaje de pacientes tiene una gran dependencia de la VMD pocas familias cuentan con ayudas específicas tanto a nivel escolar como en el domicilio, y el seguimiento sanitario es heterogéneo y poco coordinado(AU)

Introduction: Domiciliary mechanical ventilation (DMV) use is increasing in children. Few studies have analysed the characteristics of patients using this technique. Materials and methods: An observational, descriptive, transversal, multicentre study was conducted on patients between 1 month and 16 years of age dependent on domiciliary mechanical ventilation. Results: A total of 163 patients with a median age of 7.6 years from 17 Spanish hospitals were studied. The main reasons for DMV were neuromuscular disorders. The median age at beginning of DMV was 4.6 years. Almost three-quarters (71.3%) received non-invasive ventilation. Patients depending on invasive ventilation were younger, started DMV at an earlier age, and had more hours of mechanical ventilation per day. The large majority (80.9%) used DMV during sleep time only, and 11.7% during the whole day. Only 3.4% of patients had external health assistance. Just under half (48.2%) were being followed up in specific DMV or multidisciplinary clinics. Almost three-quarters (72.1%) of patients attended school (42.3% with adapted schooling). Only 47.8% of school patients had specific caregivers in their schools. Conclusions: DMV in children is used in a very heterogeneous group of patients, and in an important number of patients it is started before the third year of life. Despite there being a significant proportion of patients with a high dependency on DMV, few families receive specific support at home or at school, and health care surveillance is variable and poorly coordinated(AU)

Síndrome de abstinencia en Cuidados Intensivos Pediátricos. Incidencia y factores de riesgo / Withdrawal syndrome in the pediatric intensive care unit. incidence and risk factors

Objetivo Conocer la incidencia de síndrome de abstinencia tras perfusión prolongada de fentanilo y midazolam en niños, y los factores de riesgo asociados. Diseño Estudio de cohorte histórica o retrospectiva. Ámbito UCI pediátrica de seis camas de un hospital universitario. Pacientes Se incluyen 48 pacientes pediátricos que recibieron sedoanalgesia en perfusión continua con midazolam y fentanilo exclusivamente, durante al menos 48 horas. Intervenciones Ninguna. Variables de interés principales Se recogen datos clínicos y demográficos, dosis y duración de sedoanalgesia recibida, aparición de síndrome de abstinencia, gravedad y tratamiento del mismo. Resultados El 50% desarrolló síndrome de abstinencia. Hubo diferencias significativas entre los que lo desarrollaron y los que no en cuanto a duración del tratamiento previo y dosis acumulada de ambos fármacos. Una dosis acumulada de fentanilo de 0,48mg/kg o de midazolam de 40mg/kg, y una duración de la perfusión de ambos de 5,75 días fueron factores de riesgo para el desarrollo de abstinencia. La mayoría presentó un cuadro leve o moderado, que comenzó a las 12-36 horas de suspender la perfusión. El fármaco más utilizado en el tratamiento fue la metadona. Conclusiones La incidencia de síndrome de abstinencia en niños tras perfusión prolongada de midazolam y fentanilo es elevada. El desarrollo del síndrome se relaciona con tiempos de perfusión prolongados y con dosis acumuladas elevadas de ambos fármacos (AU)

Objective To determine the incidence of withdrawal syndrome after prolonged infusion of fentanyl and midazolam in children, and the associated risk factors. Design Historic or retrospective cohort study. Setting Pediatric Intensive Care Unit in an academic center. Patients Forty-eight pediatric patients who received sedation and analgesia only with fentanyl and midazolam through continuous infusion for at least 48hours.InterventionsNone.Main variables of interest Collected data included demographic and clinical parameters, dose and duration of sedation received, and incidence, severity and treatment of withdrawal syndrome. Results Fifty percent of the patients developed withdrawal syndrome. There were significant differences between the patients who developed withdrawal syndrome and those who did not, in terms of the duration of infusion and the cumulative doses of both drugs. A cumulative fentanyl dose of 0.48mg/kg, a cumulative midazolam dose of 40mg/kg, and a duration of infusion of both drugs of 5.75 days were risk factors for the development of withdrawal syndrome. Most children developed mild or moderate disease, beginning about 12-36hours after weaning from infusion. Methadone was used in most cases for treating with drawal. Conclusions There is a high incidence of withdrawal syndrome in children following the continuous infusion of midazolam and fentanyl. The duration of infusion of both drugs and higher cumulative doses are associated with the development of withdrawal syndrome (AU)

Withdrawal syndrome in the pediatric intensive care unit. Incidence and risk factors.

OBJECTIVE: To determine the incidence of withdrawal syndrome after prolonged infusion of fentanyl and midazolam in children, and the associated risk factors. DESIGN: Historic or retrospective cohort study. SETTING: Pediatric Intensive Care Unit in an academic center. PATIENTS: Forty-eight pediatric patients who received sedation and analgesia only with fentanyl and midazolam through continuous infusion for at least 48 hours. INTERVENTIONS: None. MAIN VARIABLES OF INTEREST: Collected data included demographic and clinical parameters, dose and duration of sedation received, and incidence, severity and treatment of withdrawal syndrome. RESULTS: Fifty percent of the patients developed withdrawal syndrome. There were significant differences between the patients who developed withdrawal syndrome and those who did not, in terms of the duration of infusion and the cumulative doses of both drugs. A cumulative fentanyl dose of 0.48 mg/kg, a cumulative midazolam dose of 40 mg/kg, and a duration of infusion of both drugs of 5.75 days were risk factors for the development of withdrawal syndrome. Most children developed mild or moderate disease, beginning about 12-36 hours after weaning from infusion. Methadone was used in most cases for treating withdrawal. CONCLUSIONS: There is a high incidence of withdrawal syndrome in children following the continuous infusion of midazolam and fentanyl. The duration of infusion of both drugs and higher cumulative doses are associated with the development of withdrawal syndrome.

[Domiciliary mechanical ventilation in children: a Spanish multicentre study]. / Ventilación mecánica domiciliaria en niños: estudio multicéntrico español.

INTRODUCTION: Domiciliary mechanical ventilation (DMV) use is increasing in children. Few studies have analysed the characteristics of patients using this technique. MATERIALS AND METHODS: An observational, descriptive, transversal, multicentre study was conducted on patients between 1 month and 16 years of age dependent on domiciliary mechanical ventilation. RESULTS: A total of 163 patients with a median age of 7.6 years from 17 Spanish hospitals were studied. The main reasons for DMV were neuromuscular disorders. The median age at beginning of DMV was 4.6 years. Almost three-quarters (71.3%) received non-invasive ventilation. Patients depending on invasive ventilation were younger, started DMV at an earlier age, and had more hours of mechanical ventilation per day. The large majority (80.9%) used DMV during sleep time only, and 11.7% during the whole day. Only 3.4% of patients had external health assistance. Just under half (48.2%) were being followed up in specific DMV or multidisciplinary clinics. Almost three-quarters (72.1%) of patients attended school (42.3% with adapted schooling). Only 47.8% of school patients had specific caregivers in their schools. CONCLUSIONS: DMV in children is used in a very heterogeneous group of patients, and in an important number of patients it is started before the third year of life. Despite there being a significant proportion of patients with a high dependency on DMV, few families receive specific support at home or at school, and health care surveillance is variable and poorly coordinated.

Validación de la medición transcutánea de la presión parcial de dióxido de carbono en el paciente crítico pediátrico / Validation of the transcutaneous carbon dioxide tension measurements in critical paediatric patients

Objetivo: Valorar la fiabilidad de la medición de la presión transcutánea de dióxido de carbono (PtCO2) respecto a la medición de la presión arterial de dióxido de carbono (PaCO2). Material y métodos: Estudio analítico, observacional, longitudinal y prospectivo. Cohorte de pacientes ingresados en unidad de cuidados intensivos pediátricos. La PtCO2 se midió con el monitor digital SenTec, aplicando el sensor con un anillo específico (sensor V-sign, versión MDB 04.04.02). Se recogieron al mismo tiempo la PtCO2 y PaCO2. La significación estadística de la asociación se calculó mediante el test F de Snedecor, el coeficiente de correlación r2 de Pearson y el coeficiente de correlación intraclase. El grado de acuerdo se estimó con el método de Bland y Altman. La consistencia de los resultados se estudió con el ANOVA. Resultados: Se compararon 106 mediciones pareadas de PtCO2 y PaCO2, de 12 pacientes. Las PaCO2 y PtCO2 medias fueron 51,0±13mmHg y 50,1±14mmHg; r2=0,87 (p<0,001), CCI=0,96 (IC: 0,94–0,97). El análisis de Bland-Altman mostró una media de las diferencias de−0,9mmHg (IC:−2,0 a 0,2mmHg). La correlación fue mejor en ausencia de patología respiratoria, con asistencia respiratoria baja, con PaCO2>50mmHg y con aplicación frontal del sensor. Hubo consistencia de los resultados. No se observaron efectos secundarios derivados de la utilización del anillo. Conclusiones: La correlación obtenida entre la PtCO2 y PaCO2 fue muy buena. El monitor digital SenTec y el sensor de anillo específico constituyen una herramienta fiable, segura y fácil de utiliza (AU)

Objective: To estimate the accuracy of the transcutaneous carbon dioxide tension measurement (PtCO2) compared to the measurement of the arterial carbon dioxide tension (PaCO2). Material and methods: An analytical, longitudinal, prospective and observational study, of a dynamic cohort taken from the in-patients of a Paediatric Intensive Care Unit (PICU). The PtCO2 was measured with the SenTec AG analyzer, and the sensor was applied with the specific Multi-Site Attachment Ring. PtCO2 and PaCO2 were recorded at the same time. The statistical significance of the association between paired measurements was evaluated with the Snedecor's F test, the Pearson's r2 correlation coefficient and the Interclass Correlation Coefficient (ICC). The degree of agreement was evaluated with the Bland & Altman method. The consistency of the results was evaluated with the ANalysis Of the VAriance (ANOVA). Results: One hundred and six paired measurements, PtCO2 and PaCO2, from twelve patients, were compared. The means of the PaCO2 and PtCO2 were 51.0±13mmHg and 50.1±14mmHg, respectively; r2=0.87 (p<0.001), ICC=0.96, (95% CI: 0.94–0.97). The Bland-Altman analysis showed a mean difference of−0.9mmHg (95% CI:−2.0 to 0.2mmHg). The correlation was better in cases with no respiratory disease, with low respiratory assistance, with PaCO2>50mmHg and with the sensor applied on the forehead. The results were consistent. No side effects derived from the use of the ring were observed. Conclusion: The correlation between PtCO2 and PaCO2 is excellent and stable. The ring sensor was safe and easy to us (AU)

[Validation of the transcutaneous carbon dioxide tension measurements in critical paediatric patients]. / Validación de la medición transcutánea de la presión parcial de dióxido de carbono en el paciente crítico pediátrico.

OBJECTIVE: To estimate the accuracy of the transcutaneous carbon dioxide tension measurement (PtCO(2)) compared to the measurement of the arterial carbon dioxide tension (PaCO(2)). MATERIAL AND METHODS: An analytical, longitudinal, prospective and observational study, of a dynamic cohort taken from the in-patients of a Paediatric Intensive Care Unit (PICU). The PtCO(2) was measured with the SenTec AG analyzer, and the sensor was applied with the specific Multi-Site Attachment Ring. PtCO(2) and PaCO(2) were recorded at the same time. The statistical significance of the association between paired measurements was evaluated with the Snedecor's F test, the Pearson's r(2) correlation coefficient and the Interclass Correlation Coefficient (ICC). The degree of agreement was evaluated with the Bland & Altman method. The consistency of the results was evaluated with the ANalysis Of the VAriance (ANOVA). RESULTS: One hundred and six paired measurements, PtCO(2) and PaCO(2), from twelve patients, were compared. The means of the PaCO(2) and PtCO(2) were 51.0+/-13mmHg and 50.1+/-14mmHg, respectively; r(2)=0.87 (p<0.001), ICC=0.96, (95% CI: 0.94-0.97). The Bland-Altman analysis showed a mean difference of-0.9mmHg (95% CI:-2.0 to 0.2mmHg). The correlation was better in cases with no respiratory disease, with low respiratory assistance, with PaCO(2)>50mmHg and with the sensor applied on the forehead. The results were consistent. No side effects derived from the use of the ring were observed. CONCLUSION: The correlation between PtCO(2) and PaCO(2) is excellent and stable. The ring sensor was safe and easy to use.

Normal neurological outcome after congenital thyrotoxicosis: prognostic value of observation of general movements.

We followed up a patient born preterm with congenital thyrotoxicosis by observing her general movements (GMs) in accordance with Prechtl's method. Initially a chaotic pattern was observed. Along with the normalization of thyroid hormones, the GM pattern changed to a poor repertoire at four weeks of life, full-blown writhing movements at six weeks and fidgety movements at the age of four months. This is the first report of chaotic GMs in a neonate reflecting transient neurological dysfunction related to congenital thyrotoxicosis, with subsequent normal neurological and cognitive outcome.

[Neonatal respiratory failure associated with mutation in the surfactant protein C gene]. / Insuficiencia respiratoria neonatal asociada a mutación en el gen de la proteína C del surfactante.

Respiratory insufficiency in a term infant during the first weeks of life is unusual. Possible causes include interstitial or diffuse lung disease, which are a heterogeneous group of mostly idiopathic disorders, characterized by diffuse infiltrates, restrictive functional defect, and disordered gas exchange. A form of interstitial lung disease that can affect infants, children or young adults is that associated with congenital surfactant protein B or C deficiency, in which the inflammatory process leading to interstitial fibrosis is preceded by the accumulation of proteinaceous material in the alveolar space. We assessed the role of potential abnormalities in the surfactant proteins B and C in a Spanish family in which two infants showed progressive neonatal respiratory failure associated with radiological and pathological alterations compatible with interstitial lung disease. The father had a history of respiratory disease since childhood. The two affected children in this family had abnormal expression of surfactant C precursor protein, with markedly decreased levels of the mature protein. Moreover, a previously unreported mutation in the gene encoding surfactant protein C, which was found in this family, is described.

Insuficiencia respiratoria neonatal asociada a mutación en el gen de la proteína C del surfactante / Neonatal respiratory failure associated with mutation in the surfactant protein C gene

La insuficiencia respiratoria en el recién nacido a término durante las primeras semanas de vida extrauterina es una situación poco frecuente. Entre sus causas se incluyen las enfermedades difusas del intersticio pulmonar, un grupo heterogéneo de enfermedades, la mayoría idiopáticas, caracterizadas por infiltrados difusos, alteraciones funcionales de tipo restrictivo y afectación del intercambio gaseoso. Una forma de enfermedad pulmonar intersticial que puede afectar a lactantes, niños o adultos jóvenes es la que se asocia al déficit congénito de proteínas B o C del surfactante pulmonar. En estos casos los procesos inflamatorios que evolucionan hacia la fibrosis pulmonar están precedidos por la acumulación de material proteináceo en el alvéolo. Se indagó la presencia de mutaciones en los genes de las proteínas B y C del surfactante en una familia española en la cual dos lactantes presentaron insuficiencia respiratoria progresiva desde el nacimiento, con alteraciones radiológicas y anatomopatológicas compatibles con enfermedad del intersticio pulmonar, y el padre refería historia de problemas respiratorios desde la infancia. Se encontró que los dos hermanos de esta familia afectados por la enfermedad presentaban una expresión anómala del precursor de la proteína C del surfactante y concentraciones muy bajas de proteína madura. Se describe además una mutación nueva en el gen que codifica la proteína C del surfactante y que cosegrega con la enfermedad en esta familia

Respiratory insufficiency in a term infant during the first weeks of life is unusual. Possible causes include interstitial or diffuse lung disease, which are a heterogeneous group of mostly idiopathic disorders, characterized by diffuse infiltrates, restrictive functional defect, and disordered gas exchange. A form of interstitial lung disease that can affect infants, children or young adults is that associated with congenital surfactant protein B or C deficiency, in which the inflammatory process leading to interstitial fibrosis is preceded by the accumulation of proteinaceous material in the alveolar space. We assessed the role of potential abnormalities in the surfactant proteins B and C in a Spanish family in which two infants showed progressive neonatal respiratory failure associated with radiological and pathological alterations compatible with interstitial lung disease. The father had a history of respiratory disease since childhood. The two affected children in this family had abnormal expression of surfactant C precursor protein, with markedly decreased levels of the mature protein. Moreover, a previously unreported mutation in the gene encoding surfactant protein C, which was found in this family, is described

FES-Cre targets phosphatidylinositol glycan class A (PIGA) inactivation to hematopoietic stem cells in the bone marrow.

A somatic mutation in the X-linked phosphatidylinositol glycan class A (PIGA) gene causes the loss of glycosyl phosphatidylinositol (GPI)-linked proteins on blood cells from patients with paroxysmal nocturnal hemoglobinuria. Because all blood cell lineages may be affected it is thought that the mutation occurs in a hematopoietic stem cell. In transgenic mice, germline transmission of an inactive Piga gene is embryonic lethal. To inactivate the murine Piga gene in early hematopoiesis we therefore chose conditional gene inactivation using the Cre/loxP system. We expressed Cre recombinase under the transcription regulatory sequences of the human c-fes gene. FES-Cre inactivated PIGA in hematopoietic cells of mice carrying a floxed Piga allele (LF mice). PIGA(-) cells were found in all hematopoietic lineages of definitive but not primitive hematopoiesis. Their proportions were low in newborn mice but subsequently increased continuously to produce for the first time mice that have almost exclusively PIGA(-) blood cells. The loss of GPI-linked proteins occurred mainly in c-kit(+)CD34(+)Lin(-) progenitor cells before the CFU-GEMM stage. Using bone marrow reconstitution experiments with purified PIGA(-) cells we demonstrate that LF mice have long-term bone marrow repopulating cells that lack GPI-linked proteins, indicating that recombination of the floxed Piga allele occurs in the hematopoietic stem cell.

Mzf1 controls cell proliferation and tumorigenesis.

MZF1 is a transcription factor belonging to the Krüppel family of zinc finger proteins, expressed in totipotent hemopoietic cells as well as in myeloid progenitors. Here we have inactivated Mzfi1 by gene targeting. Mzf1(-/-) mice develop lethal neoplasias characterized by the infiltration and complete disruption of the liver architecture by a monomorphic population of cells of myeloid origin reminiscent of human chloromas. Mzf1 inactivation results in a striking increase of the autonomous cell proliferation and of the ability of Mzf1(-/-) hemopoietic progenitors to sustain long-term hemopoiesis. These findings demonstrate that Mzf1 can act as a tumor/growth suppressor in the hemopoietic compartment.

PML is essential for multiple apoptotic pathways.

The PML gene of acute promyelocytic leukaemia (APL) encodes a cell growth and tumour suppressor, however, the mechanisms by which PML suppresses tumorigenesis are poorly understood. We show here that Pml is required for Fas- and caspase-dependent DNA-damage-induced apoptosis. We also found that Pml is essential for induction of programmed cell death by Fas, tumour necrosis factor alpha (TNF), ceramide and type I and II interferons (IFNs). As a result, Pml-/- mice and cells are protected from the lethal effects of ionizing radiation and anti-Fas antibody. Pml is required for caspase 1 and caspase 3 activation upon exposure to these stimuli. The PML-RAR alpha fusion protein of APL renders haemopoietic progenitor cells resistant to Fas-, TNF- and IFN-induced apoptosis with a lack of caspase 3 activation, thus acting as a Pml dominant-negative product. These results demonstrate that Pml is a mediator of multiple apoptotic signals, and implicate inhibition of apoptosis in the pathogenesis of APL.

Acute promyelocytic leukemia as a model for cross-talk between interferon and retinoic acid pathways: from molecular biology to clinical applications.

Acute promyelocytic leukemia (APL) has been regarded as the paradigm for therapeutic approaches utilizing differentiating agents, due to the fact that almost 95% of patients undergo complete remission when treated with all-trans retinoic acid (ATRA). However, complete clinical remission with ATRA alone is always transient, and relapse in APL is almost invariably associated with the acquisition of resistance to ATRA. Acquired resistance to ATRA in APL cell lines and in some APL clinical cases can be partially overcome by interferons (IFNs), cytokines which have well established tumor-growth suppressive activities. APL is associated in 99% of cases with a 15;17 translocation that fuses the PML and Retinoic Acid Receptor alpha (RARalpha) genes. RARalpha is one of the Retinoic Acid (RA) nuclear receptors which mediates, at the transcriptional level, ATRA differentiating and growth suppressive activity. PML is a tumor-growth suppressor whose expression is directly regulated by IFNs. Here we review the molecular mechanisms by which IFNs and RA can cooperate in controlling cell growth and differentiation of normal hemopoietic cells and leukemic cells, focusing on APL as a model system.

Inhibition of cell proliferation by the interferon-inducible 204 gene, a member of the Ifi 200 cluster.

The role of the IFN-inducible p204 as growth regulator was investigated by transfecting an expression vector constitutively expressing p204 into several cell lines. Like pRB and p107, p204 is a potent growth inhibitor in sensitive cells, as demonstrated by the cell focus assay. Since stable transfectants of sensitive lines constitutively overexpressing p204 could not be established in vitro, we inserted the 204 cDNA into a vector bearing an heavy-metal-inducible promoter. Here we show that proliferation of B6MEF fibroblasts lacking endogenous p204 is strongly inhibited by transient p204 expression in the nucleus. p204 delays G1 progression into the S-phase and cells accumulate with a DNA content equivalent to cells arrested in late G1. Moreover, the role of p204 in the control of cell growth in vivo was investigated by generating transgenic mice in which the Ifi 204 gene was constitutively expressed in all tissues. To this end, expression vectors bearing the 204 cDNA under the control of the SV40 viral promoter were constructed. The overexpression of the p204 transgene achieved by injecting fertilized mouse eggs with these vectors was compatible with embryo development up to the four-cell stage in an in vitro follow-up of 4.5 days. However, no viable animals with an intact copy of the transgene were obtained, suggesting that high and constitutive levels of p204 expression can impair normal embryo development. These findings indicate that p204 plays a negative role in growth regulation and provide new information about the molecular mechanisms exploited by IFNs to inhibit cell proliferation.

Role of PML in cell growth and the retinoic acid pathway.

The PML gene is fused to the retinoic acid receptor alpha (RARalpha) gene in chromosomal translocations associated with acute promyelocytic leukemia (APL). Ablation of murine PML protein by homologous recombination revealed that PML regulates hemopoietic differentiation and controls cell growth and tumorigenesis. PML function was essential for the tumor-growth-suppressive activity of retinoic acid (RA) and for its ability to induce terminal myeloid differentiation of precursor cells. PML was needed for the RA-dependent transactivation of the p21WAF1/CIP1 gene, which regulates cell cycle progression and cellular differentiation. These results indicate that PML is a critical component of the RA pathway and that disruption of its activity by the PML-RARalpha fusion protein may be important in APL pathogenesis.