Ectomycorrhizal fungi and soil enzymes exhibit contrasting patterns along elevation gradients in southern Patagonia.

The biological and functional diversity of ectomycorrhizal (ECM) associations remain largely unknown in South America. In Patagonia, the ECM tree Nothofagus pumilio forms monospecific forests along mountain slopes without confounding effects of vegetation on plant-fungi interactions. To determine how fungal diversity and function are linked to elevation, we characterized fungal communities, edaphic variables, and eight extracellular enzyme activities along six elevation transects in Tierra del Fuego (Argentina and Chile). We also tested whether pairing ITS1 rDNA Illumina sequences generated taxonomic biases related to sequence length. Fungal community shifts across elevations were mediated primarily by soil pH with the most species-rich fungal families occurring mostly within a narrow pH range. By contrast, enzyme activities were minimally influenced by elevation but correlated with soil factors, especially total soil carbon. The activity of leucine aminopeptidase was positively correlated with ECM fungal richness and abundance, and acid phosphatase was correlated with nonECM fungal abundance. Several fungal lineages were undetected when using exclusively paired or unpaired forward ITS1 sequences, and these taxonomic biases need reconsideration for future studies. Our results suggest that soil fungi in N. pumilio forests are functionally similar across elevations and that these diverse communities help to maintain nutrient mobilization across the elevation gradient.

Quality assessment of the human genome sequence.

As the final sequencing of the human genome has now been completed, we present the results of the largest examination of the quality of the finished DNA sequence. The completed study covers the major contributing sequencing centres and is based on a rigorous combination of laboratory experiments and computational analysis.

The sequence and analysis of duplication-rich human chromosome 16.

Human chromosome 16 features one of the highest levels of segmentally duplicated sequence among the human autosomes. We report here the 78,884,754 base pairs of finished chromosome 16 sequence, representing over 99.9% of its euchromatin. Manual annotation revealed 880 protein-coding genes confirmed by 1,670 aligned transcripts, 19 transfer RNA genes, 341 pseudogenes and three RNA pseudogenes. These genes include metallothionein, cadherin and iroquois gene families, as well as the disease genes for polycystic kidney disease and acute myelomonocytic leukaemia. Several large-scale structural polymorphisms spanning hundreds of kilobase pairs were identified and result in gene content differences among humans. Whereas the segmental duplications of chromosome 16 are enriched in the relatively gene-poor pericentromere of the p arm, some are involved in recent gene duplication and conversion events that are likely to have had an impact on the evolution of primates and human disease susceptibility.

The DNA sequence and comparative analysis of human chromosome 5.

Chromosome 5 is one of the largest human chromosomes and contains numerous intrachromosomal duplications, yet it has one of the lowest gene densities. This is partially explained by numerous gene-poor regions that display a remarkable degree of noncoding conservation with non-mammalian vertebrates, suggesting that they are functionally constrained. In total, we compiled 177.7 million base pairs of highly accurate finished sequence containing 923 manually curated protein-coding genes including the protocadherin and interleukin gene families. We also completely sequenced versions of the large chromosome-5-specific internal duplications. These duplications are very recent evolutionary events and probably have a mechanistic role in human physiological variation, as deletions in these regions are the cause of debilitating disorders including spinal muscular atrophy.

The DNA sequence and biology of human chromosome 19.

Chromosome 19 has the highest gene density of all human chromosomes, more than double the genome-wide average. The large clustered gene families, corresponding high G + C content, CpG islands and density of repetitive DNA indicate a chromosome rich in biological and evolutionary significance. Here we describe 55.8 million base pairs of highly accurate finished sequence representing 99.9% of the euchromatin portion of the chromosome. Manual curation of gene loci reveals 1,461 protein-coding genes and 321 pseudogenes. Among these are genes directly implicated in mendelian disorders, including familial hypercholesterolaemia and insulin-resistant diabetes. Nearly one-quarter of these genes belong to tandemly arranged families, encompassing more than 25% of the chromosome. Comparative analyses show a fascinating picture of conservation and divergence, revealing large blocks of gene orthology with rodents, scattered regions with more recent gene family expansions and deletions, and segments of coding and non-coding conservation with the distant fish species Takifugu.

Myasthenia Gravis and its Association With Thyroid Diseases.

Myasthenia gravis (MG) is a rare autoimmune neuromuscular junction disorder, and thyroid disorder is a disorder involving the thyroid receptor, of which Graves' disease (GD) is the most common autoimmune thyroid disorder, in which antibodies develop against thyroid receptors. Both may have similar clinical features. In myasthenia gravis, autoimmune antibodies develop against postsynaptic neuromuscular junction disrupting the neuromuscular transmission, resulting in fluctuating muscle weakness and fatigue. It is a disease of young women and older men. The two pathologies may coexist in a patient or can precede one another. Graves' disease (GD) among thyroid diseases is most often associated with MG.  Similarities in clinical features lead to difficulty in distinguishing MG and GD. Despite the standard treatment of myasthenia gravis, including steroids, acetylcholinesterases, rituximab, immunosuppressants, and thymectomy, there is still an increased number of relapses and myasthenia crisis. Eculizumab and plasmapheresis are the two new treatment options for MG, with supporting evidence of marked improvement in recent studies. Myasthenia gravis and Graves' disease have a see-saw relationship. Treating one pathology may worsen the other, so physicians should always consider MG as a differential in patients of hyperthyroidism presenting with new symptoms of fatigue or respiratory failure or neuromuscular weakness. In this comprehensive review article, we tried to establish an association between myasthenia gravis and Graves' disease (GD) by exploring currently available literature from PubMed. However, more studies need to be done to establish an association between pathologies.

Pathogenesis of Ventricular Arrhythmias and Its Effect on Long-Term Prognosis in Patients With Takotsubo Cardiomyopathy.

Takotsubo cardiomyopathy (TTC), also known as broken heart syndrome, stress cardiomyopathy (SCM), or apical ballooning syndrome, is a non-ischemic cardiac disease with an initial clinical presentation that is very similar to acute coronary syndrome (ACS). Ventricular arrhythmias (VAs) contribute significantly to an increase in the rates of death in patients with TTC, especially during the acute phase, in which patients with TTC are more susceptible to develop life-threatening arrhythmias (LTA) such as ventricular tachycardia (VT), ventricular fibrillation (VF), torsades de pointes (TdP), and sudden cardiac death (SCD). However, the pathophysiology of TTC and how VA occurs are still a mystery. We aim to review previous literature and discuss the possible mechanisms of VA in TTC patients. VA usually complicates the acute phase of the disease and worsens the long-term prognosis. Alterations of repolarization (negative T wave, prolonged QTc) indicate a high risk of arrhythmic events (TdP, VT, VF, and SCD). Catecholamine effect on myocardial cells and myocardial edema can create a substrate for the development of VA. Some of the most commonly proposed mechanisms for the development of VA in patients with TTC are coronary vasospasm, myocardial stunning due to catecholamines, re-entry, and triggered activity. Further prospective studies, including a more significant number of patients, are required to understand the disease's pathophysiology better and improve LTA management in patients with TTC.

The Future of Metformin in the Prevention of Diabetes-Related Osteoporosis.

As a worldwide aging population is on the rise, osteoporosis (OS) is becoming a global health burden. Therefore, many researchers and health authorities are looking into the potential prevention and treatment of OS. Although previously regarded as two separate pathological processes, diabetes (DM) and OS are now regarded as two conditions that can occur together. It is now believed that OS can develop as a complication of DM. This relationship is further evidenced through a reduction in bone mineral density in type-1 diabetes with a resulting increased risk of fracture. Although bone mineral density in type-2 diabetes mellitus is normal or increased, there is also increased fragility due to decreased bone quality. These abnormal bone qualities tend to occur through the production of reduced bone microvasculature and advanced glycation end product, AGE. Interestingly, one of the most common treatments for DM, metformin (MF), shows a promising result on the protection of diabetes and non-diabetes related bone turnover. It is believed that MF modulates its effect through the adenosine monophosphate-activated protein kinase (AMPK) pathway. Recent data regarded AMPK as a vital mediator of homeostasis. It is involved not only in glucose metabolism but also in osteogenesis. AMPK can directly influence the production of mature and good quality bone by decreasing osteoclasts, increasing osteoblast formation, and enhancing bone mineral deposition. As an activator of AMPK, MF also upregulates osteogenesis. Furthermore, MF can influence osteogenesis through a non-AMPK pathway, such as the fructose 1-6 phosphatase pathway, by reducing glucose levels. While already recognized as a safe and effective treatment for DM, this article discusses whether MF can be used for the prevention and treatment of OS.

Spatial abundance models and seasonal distribution for guanaco (Lama guanicoe) in central Tierra del Fuego, Argentina.

Spatially explicit modelling allows to estimate population abundance and predict species' distribution in relation to environmental factors. Abiotic factors are the main determinants of a herbivore´s response to environmental heterogeneity on large spatiotemporal scales. We assessed the influence of elevation, geographic location and distance to the coast on the seasonal abundance and distribution of guanaco (Lama guanicoe) in central Tierra del Fuego, by means of spatially explicit modelling. The estimated abundance was 23,690 individuals for the non-breeding season and 33,928 individuals for the breeding season. The factors influencing distribution and abundance revealed to be the elevation for the non-breeding season, and the distance to the coast and geographic location for the breeding season. The southwest of the study area presented seasonal abundance variation and the southeast and northeast presented high abundance during both seasons. The elevation would be the driving factor of guanaco distribution, as individuals move to lower areas during the non-breeding season and ascend to high areas during the breeding season. Our results confirm that part of the guanaco population performs seasonal migratory movements and that the main valleys present important wintering habitats for guanacos as well as up-hill zones during summer. This type of study would help to avoid problems of scale mismatch and achieve better results in management actions and is an example of how to assess important seasonal habitats from evaluations of abundance and distribution patterns.

Human neural stem/progenitor cells derived from the olfactory epithelium express the TrkB receptor and migrate in response to BDNF.

Neurogenesis constitutively occurs in the olfactory epithelium of mammals, including humans. The fact that new neurons in the adult olfactory epithelium derive from resident neural stem/progenitor cells suggests a potential use for these cells in studies of neural diseases, as well as in neuronal cell replacement therapies. In this regard, some studies have proposed that the human olfactory epithelium is a source of neural stem/progenitor cells for autologous transplantation. Although these potential applications are interesting, it is important to understand the cell biology and/or whether human neural stem/progenitor cells in the olfactory epithelium sense external signals, such as brain-derived neurotrophic factor (BDNF), that is also found in other pro-neurogenic microenvironments. BDNF plays a key role in several biological processes, including cell migration. Thus, we characterized human neural stem/progenitor cells derived from the olfactory epithelium (hNS/PCs-OE) and studied their in vitro migratory response to BDNF. In the present study, we determined that hNS/PCs-OE express the protein markers Nestin, Sox2, Ki67 and ßIII-tubulin. Moreover, the doubling time of hNS/PCs-OE was approximately 38h. Additionally, we found that hNS/PCs-OE express the BDNF receptor TrkB, and pharmacological approaches showed that the BDNF-induced (40ng/ml) migration of differentiated hNS/PCs-OE was affected by the compound K252a, which prevents TrkB activation. This observation was accompanied by changes in the number of vinculin adhesion contacts. Our results suggest that hNS/PCs-OE exhibit a migratory response to BDNF, accompanied by the turnover of adhesion contacts.

Valores de procalcitonina en pacientes diagnosticados como sepsis bacteriana en una Unidad de Cuidado Intensivo / Procalcitonin values in patients diagnosed with bacterial sepsis at an Intensive Care Unit

Antecedentes: El diagnóstico bacteriológico de sepsis grave y shock séptico en las Unidades de Cuidado Intensivo es muy complejo y demorado, por lo que se están explorando biomarcadores de inflamación como alternativa. Objetivo: Evaluar el comportamiento de los niveles séricos de procalcitonina (PCT), en casos de pacientes diagnosticados al ingreso como síndrome de respuesta inflamatoria sistémica (SRIS), y que posteriormente registraron cultivos bacterianos positivos para diversos microorganismos de tipo bacteriano. Materiales y métodos: Estudio observacional, longitudinal prospectivo de cohorte única; mediante muestreo aleatorio secuencial. Se reclutaron 98 pacientes, con al menos 2 criterios diagnósticos de SRIS, y a todos se les realizó medición diaria de los niveles de procalcitonina y cultivo microbiológico. Se incluyeron otras variables como edad, sexo y desenlace al egreso. Resultados: Media de edad 62,6 años (SD = 17,5); 67,3% de sexo masculino (n = 66); Los gérmenes cultivados con mayor frecuencia fueron E. coli, S. aureus, S. epidermidis, P. aeruginosa y Klebsiella spp.; niveles de PCT por encima de 0,5 ng/ml y al menos 2 criterios diagnósticos de SRIS se registraron en 85% de los pacientes al ingreso. Al tercer día el 96% habían registrado niveles elevados de PCT. Los niveles promedio de PCT fueron más elevados en pacientes infectados con S. aureus y en los que fallecieron antes de 5 días. No se registraron diferencias estadísticamente significativas por sexo y edad. Conclusiones: La PCT se perfila como un biomarcador útil y confiable para el diagnóstico en casos de sepsis y choque séptico en Unidades de Cuidado Intensivo y Servicios de Emergencias; de la misma manera, la medición secuencial de los niveles séricos de PCT podría ayudar a esclarecer el pronóstico.

Background: Bacteriological diagnosis of severe sepsis and septic shock in intensive care units is complex and time consuming; as an alternative, biomarkers of inflammation are being explored. Objective: To assess the performance of serum levels of procalcitonin (PCT) in patients admitted and diagnosed with Systemic Inflammatory Response Syndrome (SIRS) and afterwards had positive bacterial cultures to several microorganisms. Materials and methods: Observational, prospective cohort longitudinal study. A total of 98 patients were enrolled by sequential random sampling; all met at least two SIRS diagnostic criteria. All patients underwent daily measurements of PCT levels and microbiological cultures. We recorded additional variables such as age, sex, and outcome at discharge. Results: The mean age was 62.6 years (SD = 17.5), with 67.3% males (n = 66). The organisms most frequently found were: E. coli, S. aureus, S. epidermidis, P. aeruginosa and Klebsiella spp. PCT levels above 0.5 ng/mL and at least two diagnoses meeting SIRS criteria were recorded in 85% of patients at the time of admission. On the third day, 96% registered high levels of PCT. PCT mean levels were higher in patients infected with S. aureus and in those who died within 5 days. There were no statistically significant differences in terms of sex or age. Conclusions: PCT is a useful and reliable diagnostic biomarker in cases of sepsis and septic shock. The sequential measurement of serum PCT levels may help determine the prognosis.

Factores de riesgo de accidentes en niños que consultaron al Policlínico Infantil de Medellín Diciembre 1 de 1998 - marzo 6 de 1999 / Risk factors for accidents in children that consulted to the emergency unit of San Vicente de Paul Children´s Hospital of Medellin, Colombia, December 1, 1998 - March 6, 1999

Se hizo un estudio descriptivo prospectivo para identificar los factores de riesgo para accidentes en los niños menores de 12 años que consultaron por esta causa al Policlínico Infantil de Medellín, desde diciembre 1 de 1998 hasta marzo 6 de 1999. Se compararon dichos factores durante un período de vacaciones escolares y uno de actividad académica de igual duración.Se trabajó con 1.185 pacientes. La distribución por sexo fue: 771 niños (65 por ciento) y 414 niñas (35 por ciento); el 76,9 por ciento (912 pacientes) procedían de Medellín y su área metropolitana. El lugar del accidente fue como sigue: en la calle 582 niños (49 por ciento); en el hogar 496 niños (41,9 por ciento), en la escuela 32 niños (2,7 por ciento) y en otros sitios 75 niños (6,3 por ciento). Se encontraban solos en el momento del accidente 199 niños (16,8 por ciento), con otros niños 512 (43,2 por ciento) y con adultos 474 (40 por ciento). El principal tipo de accidente fue el mecánico en 1.077 casos (90,9 por ciento); 740 niños sufrieron caídas lo que representó el 62,5 por ciento de todos los accidentes. El accidente por vehículos de motor representó el 10,3 por ciento (123 casos). El trauma fue leve en 1.128 niños (95,2 por ciento). La letalidad fue del 0,7 por ciento (8 niños), especialmente por trauma craneoencefálico debido a accidentes de tránsito y heridas por arma de fuego. El trauma fue más grave en los menores de 2 años.Se encontró diferencia estadísticamente significativa en la frecuencia de traumas entre el período de vacaciones y el académico, con más accidentes durante las vacaciones.Se recomienda iniciar programas de prevención de accidentes especialmente en el hogar, dirigidos a los padres y cuidadores de los menores, con énfasis en las etapas de desarrollo de los niños y los riesgos para los diferentes tipos de accidentes.

Invader species in Argentina: a review about the beaver (castor canadenis) population situation on tierra del fuego ecosystem

Los castores (Castor canadensis) fueron introducidos en la Isla Grande de Tierra del Fuego Argentina en 1946. La ausencia de predadores y competidores naturales y la abundancia de alimento y sitios de refugio favorecieron su rápida expansión y crecimiento poblaional. Este artpiculo muestra el estado poblacional y las modificaciones al paisaje producida por los castores en estos ecosistemas australes. Actualmente los castores son encontrados en todos los ríos de las áreas andina y extra-andina y en casi la totalidad de hábitats acuáticos de la Isla Grande como también otras islas chilenas del Archipiélago de Tierra dl Fuego (70000 Km2). Áreas con orden de gradiente bajo en recursos de agua pequeños son ocupadps más densamente que aquellos de valles en pendiente. Las densdidades son similares a las de Hemisfério Norte. Los hábitats más colonizados mostraron una abundancia de 0,7 colonias activas por Km2. Cuatro clases (A, B, C y D) para usar en manjo y planificación de recursos naturales, fueron determinadas sobre la frecuencia de los sitios de colonia y el patrón de ocupación del castor en las cuancas. Las altas densidades en las clases C y D (4,7 y 5,8 sitios de colonia por Km de cuenca) indican que, potencialmente, ambas áreas tuvieron la mayor productividad. Los sitios alterados por castor tuvieron niveles de N orgánico e inorgánico altos sugiriendo que los cambios hidrológicos estacionales podrían afectar nitrificación y desnitrificación, permitiendo también la acumulación de C y P en el curso de agua. Los diques de castor pueden ser considerados fuentes de nutrientes esenciales (N y P) y C. Los análisis cromosómicos no mostraron diferencias en el cariotipo de Norteamérica. En la actualidad, se está analizando la estructura y variabilidad genética de la población introducida