Protein and antibody purification followed by immunoprecipitation of MYB and GATA zinc finger-type maize proteins with magnetic beads.

Co-immunoprecipitation (Co-IP) is a widely used and powerful approach for studying protein-protein interactions in vivo. Here, we describe a protocol for antibody purification and immobilization followed by immunoprecipitation from plant tissue extracts using magnetic beads. The protocol has been used to detect regulators in the Zea mays phenylpropanoid pathway. The protocol is amenable to a variety of downstream assays, including western blotting and mass spectrometry. For complete details on the use and execution of this protocol, please refer to Vélez-Bermúdez et al. (2015).

Kidney transplantation outcomes in lupus nephritis: A 37-year single-center experience from Latin America.

OBJECTIVE: We assessed patient and graft outcomes and prognostic factors in kidney transplantation in patients with end-stage kidney disease (ESKD) secondary to lupus nephritis (LN) undergoing kidney transplantation from August 1977 to December 2014 in a Latin American single center. METHODS: The primary endpoint was patient survival, and the secondary endpoints were death-censored graft survival for the first renal transplant and the rate of recurrent LN (RLN). Kaplan-Meier method was used for survival analysis. Factors predicting patient and death-censored graft survivals were examined by Cox proportional-hazards regression analyses. RESULTS: 185 patients were retrospectively evaluated. Patient survival rates were 88% at one year, 82% at three years, 78% at five years, and 67% at ten years. Death-censored graft survival for the first renal transplant was 93% at one year, 89% at three years, 87% at five years, and 80% at ten years. RLN was diagnosed in 2 patients (1.08%), but no graft was lost because of RLN. Thirty-nine (21.1%) patients died, and 65 (35.1%) patients experienced graft loss during the follow-up. By multivariable analyses, older recipient age and 1-month posttransplantation eGFR <45 ml/min/1.73m2 were associated with lower patient survival and an increased risk of graft loss, while induction immunosuppressive therapy exerted a protective effect on patients' survival. In the subgroup of patients in whom disease activity was measured at the time of transplantation, a higher SLEDAI score was also associated with lower patient survival and an increased risk of graft loss. CONCLUSION: In a mostly Mestizo population, kidney transplantation is an excellent therapeutic alternative in LN patients with ESKD. Older recipient age, an eGFR <45 ml/min/1.73m2 at one month posttransplantation, and disease activity at the time of transplantation are predictive of a lower patient and death-censored graft survival, while induction immunosuppressive therapy has a protective effect on patient survival. RLN is rare and does not influence the risk of graft loss.

Estrategias de educación en un programa de formación en cirugía pediátrica, como respuesta a la pandemia por COVID-19 / Education strategies in a pediatric surgery training program in response to the COVID-19 pandemic

Introducción. La pandemia por COVID-19 ha ocasionado cambios de todo orden en el mundo. Las medidas de emergencia han impactado de manera negativa la oportunidad en la prestación de los servicios de salud y los procesos de educación médica. Los educadores se han visto obligados a innovar y apoyarse mucho más en las tecnologías de la información y la comunicación, con el fin de lograr los objetivos de formación. Objetivo. Describir la implementación de estrategias de enseñanza para hacer frente a los retos que impone la pandemia por COVID-19 en un programa de formación en cirugía pediátrica. Métodos. Revisión de los registros y la asistencia a las actividades académicas programadas antes y después de la llegada del coronavirus a Colombia. Resultados. Como respuesta a la contingencia, y con el apoyo de las tecnologías de la información y la comunicación, se incrementó el número de actividades académicas en un 100 %, se logró duplicar la asistencia a las mismas y la participación de expertos nacionales e internacionales. Conclusión. La nueva normalidad impuesta por la pandemia por COVID-19 exige a los educadores en salud desarrollar estrategias de enseñanza y aprendizaje innovadoras las cuales, con la integración de las tecnologías disponibles, permiten enfrentar las dificultades y cumplir con los objetivos de formación en salud

Introduction. The COVID-19 pandemic has caused changes of all kinds in the world. The emergency measures have negatively affected the opportunity in the provision of health services and the medical education processes. Educators have been forced to innovate and have supported much more on information and communication technologies, in order to achieve the training objectives. Objective. To describe the implementation of teaching strategies to face the challenges posed by the COVID-19 pandemic in a pediatric surgery training program. Methods. Review of records and attendance at scheduled academic activities before and after the arrival of the coronavirus in Colombia. Results. In response to the contingency, and with the support of information and communication technologies, the number of academic activities was increased by 100%, attendance at them was doubled and the participation of national and international experts. Conclusion. The new normal imposed by the COVID-19 pandemic requires health educators to develop inno-vative teaching and learning strategies, which, with the integration of available technologies, make it possible to face difficulties and meet health-training objectives

Novel Biobased Textile Fiber from Colombian Agro-Industrial Waste Fiber.

Fique fibers, native to Colombia, are traditionally used for ropes and bags. In the extraction of long fibers for these purposes, the same amount of short fibers is generated; the short fibers are then discarded in the soil or in landfills. This agro-industrial waste is cellulose-rich and can be potentially developed into new biobased products. As an alternative use for these fibers, viscose regenerated fibers with potential applications in the textile industry were developed. Fique waste fibers were pulped (to produce fique cellulose pulp, FCP) using a 3³ design of experiment (DOE) to adjust the variables of the whitening treatment, and DOE analysis showed that time and hydrogen peroxide concentration do not have a significant effect on non-cellulosic remotion, unlike temperature. The behavior of this pulp in the production of viscose was compared against that of commercially available wood cellulose pulp (WCP). FCP showed a suitable cellulose content with a high degree of polymerization, which makes it a viable pulp for producing discontinuous viscose rayon filaments. Both pulps showed the same performance in the production of the viscose dope and the same chemical, thermal, and mechanical behavior after being regenerated.

Characterization of Root Epidermal Cell Patterning and Differentiation in Arabidopsis.

The root epidermis of Arabidopsis thaliana has been established as a model system for elucidating the mechanisms which govern the spatial patterningAbstract and morphogenesis of plant cells. Investigations into root hairs focus on various aspects of the biology of epidermal cells, using methods specifically developed to dissect the biological question under study. Despite the large number of studies related to epidermal cell differentiation, a survey of methods to analyze the phenotypic readout resulting from environmental conditions or the genetic background of the plant has not been provided so far. This protocol describes how to analyze the spatial arrangement and morphologic characteristics of cells in the root epidermis based on whole mount roots or cross sections, using confocal, scanning electron and light microscopy. This comparison of methods aids in selecting the most suitable strategy to examine the differentiation of root epidermal cells at different developmental stages.

BES1 regulates the localization of the brassinosteroid receptor BRL3 within the provascular tissue of the Arabidopsis primary root.

Brassinosteroid (BR) hormones are important regulators of plant growth and development. Recent studies revealed the cell-specific role of BRs in vascular and stem cell development by the action of cell-specific BR receptor complexes and downstream signaling components in Arabidopsis thaliana Despite the importance of spatiotemporal regulation of hormone signaling in the control of plant vascular development, the mechanisms that confer cellular specificity to BR receptors within the vascular cells are not yet understood. The present work shows that BRI1-like receptor genes 1 and 3 (BRL1 and BRL3) are differently regulated by BRs. By using promoter deletion constructs of BRL1 and BRL3 fused to GFP/GUS (green fluorescent protein/ß-glucuronidase) reporters in Arabidopsis, analysis of their cell-specific expression and regulation by BRs in the root apex has been carried out. We found that BRL3 expression is finely modulated by BRs in different root cell types, whereas the location of BRL1 appears to be independent of this hormone. Physiological and genetic analysis show a BR-dependent expression of BRL3 in the root meristem. In particular, BRL3 expression requires active BES1, a central transcriptional effector within the BRI1 pathway. ChIP analysis showed that BES1 directly binds to the BRRE present in the BRL3 promoter region, modulating its transcription in different subsets of cells of the root apex. Overall our study reveals the existence of a cell-specific negative feedback loop from BRI1-mediated BES1 transcription factor to BRL3 in phloem cells, while contributing to a general understanding of the spatial control of steroid signaling in plant development.

The regulation and plasticity of root hair patterning and morphogenesis.

Root hairs are highly specialized cells found in the epidermis of plant roots that play a key role in providing the plant with water and mineral nutrients. Root hairs have been used as a model system for understanding both cell fate determination and the morphogenetic plasticity of cell differentiation. Indeed, many studies have shown that the fate of root epidermal cells, which differentiate into either root hair or non-hair cells, is determined by a complex interplay of intrinsic and extrinsic cues that results in a predictable but highly plastic pattern of epidermal cells that can vary in shape, size and function. Here, we review these studies and discuss recent evidence suggesting that environmental information can be integrated at multiple points in the root hair morphogenetic pathway and affects multifaceted processes at the chromatin, transcriptional and post-transcriptional levels.

Discriminative gene co-expression network analysis uncovers novel modules involved in the formation of phosphate deficiency-induced root hairs in Arabidopsis.

Cell fate and differentiation in the Arabidopsis root epidermis are genetically defined but remain plastic to environmental signals such as limited availability of inorganic phosphate (Pi). Root hairs of Pi-deficient plants are more frequent and longer than those of plants grown under Pi-replete conditions. To dissect genes involved in Pi deficiency-induced root hair morphogenesis, we constructed a co-expression network of Pi-responsive genes against a customized database that was assembled from experiments in which differentially expressed genes that encode proteins with validated functions in root hair development were over-represented. To further filter out less relevant genes, we combined this procedure with a search for common cis-regulatory elements in the promoters of the selected genes. In addition to well-described players and processes such as auxin signalling and modifications of primary cell walls, we discovered several novel aspects in the biology of root hairs induced by Pi deficiency, including cell cycle control, putative plastid-to-nucleus signalling, pathogen defence, reprogramming of cell wall-related carbohydrate metabolism, and chromatin remodelling. This approach allows the discovery of novel of aspects of a biological process from transcriptional profiles with high sensitivity and accuracy.

An Inventory of Nutrient-Responsive Genes in Arabidopsis Root Hairs.

Root hairs, single cell extensions of root epidermal cells that are critically involved in the acquisition of mineral nutrients, have proven to be an excellent model system for studying plant cell growth. More recently, omics-based systems biology approaches have extended the model function of root hairs toward functional genomic studies. While such studies are extremely useful to decipher the complex mechanisms underlying root hair morphogenesis, their importance for the performance and fitness of the plant puts root hairs in the spotlight of research aimed at elucidating aspects with more practical implications. Here, we mined transcriptomic and proteomic surveys to catalog genes that are preferentially expressed in root hairs and responsive to nutritional signals. We refer to this group of genes as the root hair trophomorphome. Our analysis shows that the activity of genes within the trophomorphome is regulated at both the transcriptional and post-transcriptional level with the mode of regulation being related to the function of the gene product. A core set of proteins functioning in cell wall modification and protein transport was defined as the backbone of the trophomorphome. In addition, our study shows that homeostasis of reactive oxygen species and redox regulation plays a key role in root hair trophomorphogenesis.

A MYB/ZML Complex Regulates Wound-Induced Lignin Genes in Maize.

Lignin is an essential polymer in vascular plants that plays key structural roles in vessels and fibers. Lignification is induced by external inputs such as wounding, but the molecular mechanisms that link this stress to lignification remain largely unknown. In this work, we provide evidence that three maize (Zea mays) lignin repressors, MYB11, MYB31, and MYB42, participate in wound-induced lignification by interacting with ZML2, a protein belonging to the TIFY family. We determined that the three R2R3-MYB factors and ZML2 bind in vivo to AC-rich and GAT(A/C) cis-elements, respectively, present in a set of lignin genes. In particular, we show that MYB11 and ZML2 bind simultaneously to the AC-rich and GAT(A/C) cis-elements present in the promoter of the caffeic acid O-methyl transferase (comt) gene. We show that, like the R2R3-MYB factors, ZML2 also acts as a transcriptional repressor. We found that upon wounding and methyl jasmonate treatments, MYB11 and ZML2 proteins are degraded and comt transcription is induced. Based on these results, we propose a molecular regulatory mechanism involving a MYB/ZML complex in which wound-induced lignification can be achieved by the derepression of a set of lignin genes.

AtMYB7, a new player in the regulation of UV-sunscreens in Arabidopsis thaliana.

The phenylpropanoid metabolic pathway provides a wide variety of essential compounds for plants. Together with sinapate esters, in Brassicaceae species, flavonoids play an important role in protecting plants against UV irradiation. In this work we have characterized Arabidopsis thaliana AtMYB7, the closest homolog of AtMYB4 and AtMYB32, described as repressors of different branches of phenylpropanoid metabolism. The characterization of atmyb7 plants revealed an induction of several genes involved in flavonol biosynthesis and an increased amount of these compounds. In addition, AtMYB7 gene expression is repressed by AtMYB4. As a consequence, the atmyb4 mutant plants present a reduction of flavonol contents, indicating once more that AtMYB7 represses flavonol biosynthesis. Our results also show that AtMYB7 gene expression is induced by salt stress. Induction assays indicated that AtMYB7 represses several genes of the flavonoid pathway, DFR and UGT being early targets of this transcription factor. The results obtained indicate that AtMYB7 is a repressor of flavonol biosynthesis and also led us to propose AtMYB4 and AtMYB7 as part of the regulatory mechanism controlling the balance of the main A. thaliana UV-sunscreens.

Efectos de la infección y la enfermedad por citomegalovirus en receptores de trasplante renal / Effects of cytomegalovirus infection and disease in renal transplant recipients

La infección por citomegalovirus (CMV) es una de las más importantes causas de morbilidad en pacientes con trasplante renal. Objetivo: revisar las manifestaciones de la enfermedad aguda por este virus y sus efectos directos e indirectos sobre injerto y receptor en pacientes con trasplante renal. Material y métodos: se hizo una revisión sistemática de la literatura en la que se encontraron 40 publicaciones completas relacionadas con el tema. Conclusiones: además de la enfermedad aguda que se manifiesta con síndrome de mononucleosis o daño tisular, el CMV produce efectos indirectos sobre el injerto y el sistema vascular del receptor que parecen aumentar el riesgo de enfermedad cardiovascular y acortan la supervivencia del trasplante y el receptor. Las estrategias utilizadas en los últimos años han logrado disminuir el efecto nocivo de la enfermedad aguda por CMV, pero se desconoce su impacto sobre los efectos indirectos de la infección latente.(Acta Med Colomb 2012; 37: 131-137).

Citomegalovirus infection (CMV) is one of the major causes of morbidity in renal transplant patients. Objective: to review the manifestations of the acute viral illness and its direct and indirect effects on graft and recipient in transplant patients. Material and methods: we conducted a systematic review of the literature in which we found 40 complete publications related to the topic. Conclusions: in addition to the acute illness that manifests with mononucleosis syndrome or tissue damage, CMV has indirect effects on the graft and the receptor’s vascular system that appear to increase the risk of cardiovascular disease and shorten both graft and receiver survival. The strategies used in recent years have reduced the deleterious effect of acute CMV disease, but its impact on the indirect effects of the latent infection is unknown. (Acta Med Colomb 2012; 37: 131-137).

Sensibilidad a la amoxicilina de bacterias anaerobias de pacientes con periodontitis agresiva / Susceptibility to amoxycillin of anaerobic bacteria in patientswith aggressive periodontitis

Introducción y ObjetivoSe han utilizado los antibióticos como terapia adjunta al tratamiento periodontal. La amoxicilina y la amoxicilina/ ácido clavulánico son algunos de los más utilizados. Establecer el tipo de bacterias y su sensibilidad a la amoxicilina y a la amoxicilina/ácido clavulánico en pacientes con periodontitis agresiva. Materiales y MétodosEste estudio in vitro estableció la sensibilidad a la amoxicilina y a la amoxicilina/ácido clavulánico de las bacterias aisladas de 19 pacientes con periodontitis agresiva. Se obtuvieron muestras de 6 sitios con bolsas iguales o mayores a 7 mm de profundidad, se realizó cultivo y aislamiento de colonias en condiciones anaeróbicas. Laidentificación de los microorganismos se realizó a través de la coloración de Gram y el Sistema Crystal paraanaerobios; para determinar la sensibilidad a los antibióticos se utilizó la técnica descrita por Wilkins y Thiel.ResultadosEn la periodontitis localizada los microorganismos que se presentaron con mayor frecuencia fueron Veillonellaspecies, Peptostreptococcus prevotii, Staphylococcus saccharoliticus, Bacteroides fragilis, Bacteroidesureolyticus. En la periodontitis generalizada se encontró Fusobacterium nucleatum, Veillonella species, Peptostreptococcus prevotii, Peptostreptococcus saccharolitucus, Staphylococcus saccharoliticus. De las 21 especies identificadas, en la periodontitis localizada 4 fueron resistentes a la amoxicilina y 1 resistente a la amoxicilina/Acido clavulánico. En la periodontitis generalizada se encontró 1 microorganismo resistente a laamoxicilina y 1 resistente a la amoxicilina/Acido clavulánico.ConclusiónSe encontraron bacterias resistentes a la amoxicilina y a la amoxicilina/ácido clavulánico.

Introduction and ObjectiveAntibiotics have been used as an adjunct to periodontal treatment. Amoxicillin and amoxicillin/clavulanicacid are some of the most used.To define the type of bacteria and their susceptibility to amoxycillin and to amoxicillin/clavulanic acid inpatients with aggressive periodontitis.Materials and MethodThis descriptive study stated susceptibility to amoxycillin and to amoxicillin/clavulanic acid of bacteriaisolated from 19 patients with aggressive periodontitis, selected by convenience. Samples from six(6) different sites with periodontal pockets equal or greater than 7 mm of depth were obtained. Thesamples were cultured anaerobically and the isolated colonies were identified by means of the Gramstaining procedure and the Crystal System for anaerobics. The Wilkins and Thiel test was used to assesssusceptibility.ResultsThe microorganisms with the highest presence in localized periodontitis were Veillonella species,Peptostreptococcus prevotii, Staphylococcus saccaharolyticus, Bacteroides fragilis and Bacteroidesureolyticus. Fusobacterium nucleatum, Veillonella species, Peptostreptococcus prevotii, Peptostreptococcussaccharolyticus and Staphylococcus saccharolyticus were found in generalized periodontitis. Four out ofthe 21 microorganisms species identified in localized periodontitis 4 were resistant to amoxycillin and oneto amoxicillin/clavulanic acid. One microorganism was identified as resistant to amoxycillin and one toamoxicillin/clavulanic acid in generalized periodontitis.ConclusionAmoxycillin-resistant and amoxycillin/clavulanic acid-resistant bacteria were found.

Macrodoncias e hiperdoncias bilaterales en mandíbula: reporte de un caso clínico / Mandibular bilateral macrodontia and hyperdontia: a clinical case report

La macrodoncia es una anomalía dental con etiología desconocida, que se manifiesta en el aumento del tamañonormal comparado con el resto de la fórmula dental. La hiperdoncia es una anomalía que se manifiesta con la presencia de dientes que aumentan el número de la fórmula dental. Aunque es poco común, en algunos casos han sido reportados conjuntamente y estánasociados o no a un síndrome. Se presenta un paciente masculino de 12 años de edad que en consulta odontológica de rutina se le encuentra como hallazgo radiográfico 34, 35 y 45 impactados, macrodoncias de 34, 35 y 45 e hiperdoncias en oclusal de 34, 35 y45, sin ningún otro hallazgo patológico de importancia. Las múltiples macrodoncias y múltiples hiperdoncias son unas anomalías dentales poco frecuentes, que pueden causar patologías y desórdenes a los dientes permanentes vecinos.

Macrodontia is a dental size anomaly of unknown etiology, characterized by abnormal tooth size when comparedto the rest of the dental formula. Hyperdontia is the presence of an increased number of teeth in the dental formula. Although it is rare, in some cases both anomalies have been reported simultaneously, and they might be associated or not with a syndrome.A 12-year-old male patient who was scheduled for a routine dental exam revealed at the radiographic examination impaction of teeth 34, 35 and 45 with macrodontia of the same teeth and multiple hyperdontia (three extra teeth, located occlusal to 34, 35 and 45); no other relevant pathology was found. Multiple macrodontias and hyperdontias are rare dental anomalies that may cause pathologies and alterations to adjacent permanent teeth.

Glomerular diseases in a Hispanic population: review of a regional renal biopsy database.

CONTEXT AND OBJECTIVE: Epidemiological data provide useful information for clinical practice and investigations. This study aimed to determine glomerular disease frequencies in a region of Colombia and it represents the basis for future studies. DESIGN AND SETTING: Single-center retrospective analysis at the University of Antioquia, Colombia. METHODS: All native renal biopsies (July 1998 to December 2007) were reviewed, but only glomerular diseases were analyzed. The diagnosis of each case was based on histological, immunopathological and clinical features. RESULTS: A total of 1,040 biopsies were included. In 302 cases (29.0%), the patient's age was

Glomerular diseases in a Hispanic population: review of a regional renal biopsy database / Enfermedades glomerulares en una población hispánica: resultados de un registro regional de biopsias renales

CONTEXT AND OBJECTIVE: Epidemiological data provide useful information for clinical practice and investigations. This study aimed to determine glomerular disease frequencies in a region of Colombia and it represents the basis for future studies. DESIGN AND SETTING: Single-center retrospective analysis at the University of Antioquia, Colombia. METHODS: All native renal biopsies (July 1998 to December 2007) were reviewed, but only glomerular diseases were analyzed. The diagnosis of each case was based on histological, immunopathological and clinical features. RESULTS: A total of 1,040 biopsies were included. In 302 cases (29.0 percent), the patient's age was < 15 years. Primary glomerular diseases were diagnosed in 828 biopsies (79.6 percent) and secondary in 212 (20.4 percent). The most common primary diseases were focal and segmental glomerulosclerosis (FSGS) (34.8 percent), immunoglobulin A (IgA) nephropathy (IgAN) (11.8 percent), membranous glomerulonephritis (MGN) (10.6 percent), minimal change disease (MCD) (10.6 percent), crescentic glomerulonephritis (GN) (5.6 percent), and non-IgA mesangial proliferative GN (5.6 percent). Postinfectious GN represented 10.7 percent of the diagnoses if included as primary GN. Lupus nephritis corresponded to 17.8 percent of the entire series. In adults, the order of the most frequent primary diseases was: FSGS, IgAN, MGN, crescentic GN and MCD. In children (< 15 years), the most frequent were: FSGS, postinfectious GN, MCD, non-IgA mesangial proliferative GN, endocapillary diffuse GN and IgAN. CONCLUSIONS: As among Afro-Americans, FSGS is the most frequent type of glomerulopathy in our population, but in our group, there are more cases of IgAN. The reasons for these findings are unclear. This information is an important contribution towards understanding the prevalence of renal diseases in Latin America.

CONTEXTO Y OBJETIVO: Los datos epidemiológicos dan información útil en clínica e investigación. Nuestro objetivo fue determinar frecuencias de enfermedad glomerular en una región de Colombia y representa la base para trabajos futuros. DISEÑO Y UBICACIÓN: Análisis retrospectivo en un único centro: Universidad de Antioquia, Colombia. MÉTODOS: Todas las biopsias de riñón nativo fueron revisadas (1998 - 2007), pero solo analizamos enfermedades glomerulares. El diagnóstico en cada caso estuvo basado en histología, inmunopatología y características clínicas. RESULTS: 1.040 biopsias fueron incluidas. En 302 casos (29,0 por ciento) la edad del paciente fue < 15 años. El diagnóstico fue enfermedad primaria en 828 biopsias (79,6 por ciento) y secundaria en 212 (20,4 por ciento). Las enfermedades primarias más frecuentes fueron glomeruloesclerosis focal y segmentaria (GEFyS) (34,8 por ciento), nefropatía IgA (NIgA) (11,8 por ciento), glomerulonefritis membranosa (GNM) (10,6 por ciento), enfermedad de cambios mínimos (ECM) (10,6 por ciento), glomerulonefritis (GN) extracapilar (5,6 por ciento) y GN proliferativa mesangial no-IgA (5,6 por ciento). La GN postinfecciosa representa el 10,7 por ciento de glomerulopatías primarias. La nefritis lúpica corresponde al 17,8 por ciento de todos los casos. En adultos el orden de frecuencia de enfermedades primarias es: GEFyS, NIgA, GNM, GN extracapilar y ECM. En niños (< 15 años) las más frecuentes fueron: GEFyS, GN postinfecciosa, ECM, GN mesangial no-IgA, GN endocapilar difusa y NIgA. CONCLUSIONES: Al igual que en afro-americanos, en nuestra población la GEFyS es la glomerulopatía más frecuente, pero en nuestro grupo hay más NIgA. Las razones para estos hallazgos no se conocen. La información presentada aquí es una contribución importante para el entendimiento de la prevalencia de enfermedades renales en Latinoamérica.

Requirement of an additional Sam68 domain for inhibition of human immunodeficiency virus type 1 replication by Sam68 dominant negative mutants lacking the nuclear localization signal.

Human immunodeficiency virus type 1 (HIV-1) replication requires active nuclear export of unspliced and incompletely spliced HIV-1 RNA transcripts. This process is evolutionally made possible by expression of HIV-1 Rev, one of the three HIV-1 proteins encoded by completely spliced HIV-1 RNAs. Evidence has accumulated to suggest that Sam68 plays an important role in HIV-1 replication through HIV-1 Rev protein. In the present study, we further examined the structure-function relationship of Sam68 protein in relation to HIV-1 replication. We identified a Sam68 domain located between aa269 and aa321 to be involved in the HIV-inhibitory effects of Sam68 dominant negative mutants lacking the nuclear localization signal (NLS). Deletion of this domain abrogated inhibition of HIV-1 replication by these mutants. HIV-1 Rev protein appeared to mediate the HIV-inhibitory effects of these mutants and by this domain, as assessed by Rev-dependent chloramphenicol acetyltransferase reporter gene assay, in trans rev-defective HIV-1 complementation assay, and RNase protection assay. The HIV-inhibitory mutants containing this domain were further found to have diminished binding affinity to the wild-type Sam68 and to be associated with cytoplasmic retention of exclusively nuclear localized wild type Sam68. Taken together, these results further ascertain the important role of Sam68 in HIV-1 Rev function and viral replication, and suggest that the HIV-inhibitory effects of Sam68 dominant negative mutants directly result from their binding to endogenous Sam68 and their interference with nuclear localization of endogenous Sam68.

[The human immunodeficiency virus type 1 and the developing central nervous system]. / El virus de la inmunodeficiencia humana tipo 1 y el sistema nervioso central en desarrollo.

Currently, at least 42 million people are infected worldwide with the human immunodeficiency virus type 1 (HIV-1). Of these, 3.2 million are children infected, in 90% of the cases, through vertical transmission. In Colombia, approximately 200,000 persons have been infected since the beginning of the pandemic, with an increasing trend in the seroprevalence among pregnant women. Although HIV-1 is basically lymphotropic, its capacity to invade the central nervous system (CNS) is well known, generating multiple neurological alterations, especially prominent in children, with encephalopathy being the most prevalent. Classically, two types of neurological disorders are recognized in children, consisting of early and late encephalopathies, each with differing clinical and immunological characteristics. HIV-1 infection of the CNS is limited to macrophages, microglia and astrocytes in a restricted manner. In patients with acquired immunodeficiency virus (AIDS), neurons are rarely infected, suggesting that cellular and viral soluble factors, are responsible for the neuronal damage. The conclusion is that the CNS in earlier stages of development is especially susceptible to HIV-1 infection. The epidemiological trends predict that these types of clinical manifestations of HIV-1 will increase in frequency, and increases the necessity for an understanding of the underlying neuropathogenesis.

El virus de la inmunodeficiencia humana tipo 1 y el sistema nervioso central en desarrollo / The human immunodeficiency virus type 1 and the developing central nervous system

Actualmente, hay más de 42 millones de infectados con el virus de la inmunodeficiencia humana tipo 1 (VIH-1), de los cuales, 3,2 millones son niños y, de éstos, el 90 por ciento con transmisión vertical de la infección. Se considera que en Colombia más de 200.000 personas se han infectado desde el inicio de la pandemia y los estudios muestran una tendencia constante al aumento en las cifras de seroprevalencia en mujeres embarazadas y, por ende, en el número de recién nacidos infectados. El VIH-1 es primordialmente linfotrópico, pero su tropismo por el sistema nervioso central (SNC) es bien conocido, lo que genera múltiples alteraciones neurológicas, particularmente prominentes en niños, de las cuales la más prevalerte es la encefalopatía. Clásicamente, se reconocen dos tipos de encefalopatía en esta población: encefalopatía temprana y tardía, ambas con diferentes características clínicas e inmunológicas. La infección por el VIH-1 en el SNC está limitada a los macrófagos, la microglía y los astrocitos en menor escala. Las neuronas, células principalmente afectadas en los pacientes con sida, raras veces son infectadas, por lo que se postula que factores solubles, provenientes tanto del huésped como del virus, son los principales causantes del daño neuronal. Los hallazgos presentados en esta revisión sugieren la posibilidad de que el SNC, en etapas tempranas del desarrollo, sea especialmente susceptible a la infección por el VIH-1. Las cifras epidemiológicas sugieren que este tipo de alteraciones clínicas serán cada vez más frecuentes; de ahí, la importancia de conocer la neuropatogénesis de la infección por el VIH-1