Sergio Donoso

Association of Primary Pneumocystis carinii Infection and Sudden Infant Death Syndrome

To delineate clinical and histological features of the first Pneumocystis carinii infection affecting the immunocompetent host, P. carinii-specific histological stains were performed on autopsy lung specimens from 534 consecutive pediatric patients (those with AIDS and malignancies were excluded) in Santiago, Chile. P. carinii clusters were found in 4 (25%) of 16 infants who died of no apparent cause at arrival to the emergency department, and in 10 (2.9%) of 342 infants who died of multiple conditions at the hospital (P=.002, Fishers exact test). This prompted us to analyze additional series of infants with sudden infant death syndrome (SIDS). In 161 additional SIDS cases, 47 (35.1%) of 134 infants from Chile and 4 (14.8%) of 27 infants from Oxford, United Kingdom, were found to have P. carinii clusters in the lungs. The quantity of P. carinii cysts was small compared with the numbers seen in immunocompromised hosts with P. carinii pneumonitis. This study provides histological evidence that primary P. carinii infection is associated with SIDS.

Alcoholic drinking habit and hepatic damage

Abstract The necropsic study of hepatic lesions and the post-mortem survey which determined the alcohol drinking patterns of the 1,079 males and 269 females who died from violent death, confirm: 1. 1. That the alcoholic illness is more frequent in males than in females, although the percentage of alcoholism was more difficult to determine among women, because alcoholic behavior in them is hidden for social reasons. 2. 2. That among alcoholics whose livers present a normal structure when observed under the microscope, there is a greater deposit of intracellular fat which independent of the fat under the skin, and appears at an early age. 3. 3. That acute or subacute fatty liver, as well as cirrhosis of the Laennec type, appears significantly associated with abuse of alcohol and such lesions are evidenced later than the increase in intrahepatic fat, with no difference among sexes when similar drinking habits are compared.

Respuesta fisiológica y de crecimiento en plantas de Quillaja saponaria y Cryptocarya alba sometidas a restricción hídrica

La zona central de Chile presenta un clima mediterraneo donde las especies arboreas como Quillaja saponaria (quillay) y Cryptocarya alba (peumo) han desarrollado mecanismos fisiologicos que le permiten tolerar la falta de agua durante el verano. Se desarrollo un ensayo con plantas de dos anos de quillay y peumo, que fueron sometidas a condiciones de restriccion hidrica, en el periodo estival. Un grupo de plantas fue regado diariamente a capacidad de campo (tratamiento testigo) y otro grupo fue sometido a riego restringido hasta llegar a un potencial hidrico a pre-alba cercano a -3,5 MPa. Finalizado el periodo de restriccion hidrica, las plantas se rehidrataron. Durante el estudio se midieron variables hidricas y de crecimiento. Al finalizar el periodo de restriccion hidrica se determinaron tasas de intercambio gaseoso, asi como la distribucion de biomasa en hojas, ramas, fuste y raices. En el periodo de mayor restriccion hidrica, quillay no presento un mecanismo claro de ajuste al deficit hidrico, pero redujo su biomasa foliar en 55 % para reducir la perdida hidrica. Mientras que peumo presento ajuste osmotico. Quillay y peumo presentaron una reduccion significativa de la fotosintesis neta, conductancia estomatica y transpiracion de frente a riego restringido. La relacion parte aerea/parte radical no se modifico en peumo (1,3), y se redujo significativamente en quillay, de 2,3 a 1,4 para el tratamiento de restriccion hidrica.

Effect of shading and fertilisation on the development of container-grown Nothofagus glauca seedlings, a threatened species from central Chile

Nothofagus glauca is an endemic tree of the Mediterranean zone of Chile and is a threatened species. Currently, available information for the propagation and nursery cultivation of this species is conspicuously lacking. This study examined the effect of four levels of shade (18%, 35%, 65% and 80% with Raschel® plastic net) and four rates of slow-release fertiliser (2.5, 5, 7.5, and 10 g l−1 of Basacote® Plus 9M) on container-grown seedlings after one growing season. Growth was significantly affected by shade and fertilisation. Seedlings grown under 18% or 35% shade were larger in diameter and had more roots than those grown under 80% shade and fertilisation with 2.5–5 g l−1 of media were smaller than those fertilised with 7.5–10 g l−1.

Evaluación de la sustentabilidad de los bosques de Araucaria araucana: Producción, colecta y consumo de piñones

espanolAraucaria araucana, especie longeva, de lento crecimiento y presente desde la Era Mesozoica. En Chile habita en las cordilleras de los Andes y Nahuelbuta. La explotacion maderera y los incendios han reducido considerablemente la superficie de estos bosques. En la actualidad esta prohibida su corta, y se encuentra declarada como especie vulnerable y Monumento Natural, pero no se ha frenado su degradacion. El gran peligro que corren estos bosques en la actualidad es la excesiva cosecha de pinones y sobrecarga animal, que han ido creciendo con el aumento poblacional y valoracion economica del pinon. Basado en lo anterior el objetivo, es evaluar la produccion de conos, depredacion pinones y regeneracion, en cuatro localidades de la comuna de Lonquimay, monitoreando parcelas permanentes y pinones marcados. Se contabilizo la produccion de conos y participacion, la colecta y consumo de pinones, y la regeneracion de araucaria. La produccion de conos es heterogenea y sincronica entre las localidades. Existe una fuerte recoleccion y consumo de pinones, relacionada a la densidad poblacional. La regeneracion de araucaria esta relacionada con los niveles de recoleccion y consumo. Actualmente, no hay mecanismos que permitan regular la cosecha y depredacion de pinones, en funcion de la produccion. EnglishAraucaria araucana, long-lived species, slow growing and present from the Mesozoic Era. In Chile, inhabits the mountain ranges of the Andes and Nahuelbuta. Logging and fires have reduced significantly the area of these forests. It is currently forbidden to cut, and is declared as a vulnerable species and Natural Monument, but it has slowed its degradation. The great danger to these forests today is the excessive harvest of pine nuts and animal overload, which have been growing with population growth and economic valuation of the pinion. Based on the above, the objective is to evaluate the production of cones, pine nuts predation and regeneration, in four localities of the municipality of Lonquimay, monitoring permanent plots and marked sprockets. It was counted cone production and participation, the collection and consumption of pine nuts, and the regeneration of Araucaria. Cone production is heterogeneous and synchronous between locations. There is a strong collection and consumption of nuts, related to population density. The regeneration of Araucaria is related to the collection and consumption levels. Currently, there are not mechanisms to regulate the harvest and predation of pine nuts, depending on production.

The physiological and growth response of Acacia caven under water stress and the application of different levels of biosolids

Acacia caven (Mol.) Mol. (Leguminosae), generally known as “espino,” is one of the most common tree species in the Mediterranean region of Chile. This species grows in nutritionally poor soils with low water availability during the summer, so it is very difficult for new seedlings to become established. To investigate the effects of water restriction and the potential benefit of the application of biosolids (sludge bio-dried to 25% moisture) on the growth of the plant, a completely random, two x three factorial design was carried out in controlled nursery conditions under two irrigation regimes (well-watered plants and controlled water restriction) and three biosolid application rates (0:100, 10:90 and 20:80) in a clay substrate. Physiological evaluations (predawn water potential, photosynthesis and gas exchange) were performed at representative times along the water restriction gradients and supplemented with measurements of growth and biomass distribution. Once plants entered the water restriction phase, those in the biosolid-treated substrate exhibited better hydration compared to plants in the untreated substrate. This was attributed to the increased organic matter content as well as to changes in the textural characteristics of the original substrate that increased its capacity to deliver water to the plants. Additionally, the application of biosolids promoted shoot and leaf growth in well-watered plants, increasing the shoot:root ratio, which could be a disadvantage under water stress. Acacia c aven (Mol.) Mol. (Leguminosae), generalmente conocido como “espino”, es una de las especies arboreas mas comunes en la region mediterranea de Chile. Esta especie crece en suelos nutricionalmente pobres y con una baja disponibilidad hidrica estival, que dificulta el proceso de establecimiento de nuevas plantulas. Para investigar los efectos de la restriccion hidrica y el potencial benefico de la aplicacion de biosolidos (biosolido-seco a 25% de humedad) en el crecimiento de la planta, se establecio un ensayo con un diseno bifactorial completamente al azar en vivero bajo condiciones controladas. Se aplicaron dos tipos de riego (plantas bien regadas y restriccion hidrica controlada) y tres dosis de aplicacion de biosolidos en un sustrato arcilloso (0:100, 10:90 y 20:80). La evaluacion fisiologica (potencial hidrico a pre-alba, fotosintesis e intercambio gaseoso) fue realizada en momentos representativos del gradiente de restriccion hidrica, y fue complementada con mediciones de crecimiento y distribucion de biomasa. Cuando las plantas entraron en la fase de restriccion hidrica, aquellas que se crecieron en un sustrato con biosolido, presentaron una mejor condicion hidrica en comparacion con las plantas sin biosolido. Esto se debe a un aumento en el contenido de materia organica y a un cambio en las caracteristicas texturales del sustrato original, incrementando la capacidad para suministrar agua a las plantas. Adicionalmente, la aplicacion de biosolidos promovio el crecimiento de hojas y tallos en plantas bien regadas, e incremento la relacion tallo: raiz, que es una desventaja para la tolerancia al estres hidrico.

Influencia del raleo en el crecimiento, la condición hídrica y la respuesta fotosintética de Peumus boldus: pautas para la definición de su manejo silvicultural

Peumus boldus, especie arborea endemica de Chile central del bosque esclerofilo, por su condicion semi-xerofita se desarrolla con bajas precipitaciones y suelos pobres. Actualmente presenta estado arbustivo, debido a manejo de monte bajo por su alta capacidad de rebrote y baja regeneracion por semilla. La cosecha de P. boldus se basa principalmente en criterios economicos, faltando criterios productivos y tecnicos para definir su silvicultura. Para mejorar el manejo actual, es fundamental comprender la respuesta del rebrote despues de la cosecha. El objetivo del estudio fue evaluar la respuesta de cepas de P. boldus sometidas a diferentes intensidades de cosecha, durante los dos primeros anos despues de la corta, para establecer pautas de manejo silvicultural de la especie. Para ello se monitoreo anualmente un grupo de 23 cepas con tres niveles de cosecha: total, parcial (50 % del area basal) y sin intervencion (control). Se evaluaron las respuestas: hidrica, proceso fotosintetico mediante fluorescencia, crecimiento en diametro y acumulacion de biomasa aerea. Los resultados mostraron que las cortas mejoraron el estado hidrico de las cepas en relacion directa a la intensidad aplicada, ademas de incrementar la aparicion y crecimiento de nuevos rebrotes. Al final del segundo ano de evaluacion, la biomasa acumulada fue del 17,9 % de la biomasa inicial en las cepas con cosecha total, y del 53,6 % en las con cosecha parcial. Estos resultados muestran que cepas de P. boldus pueden ser manejadas de mejor forma, con una cosecha parcial. Nuevos estudios son necesarios para determinar la intensidad y periodicidad de la cosecha

Geostatistical Estimation of Biomass Stock in Chilean Native Forests and Plantations

There are a variety of approaches to estimate above ground biomass (AGB), which can be classified according to the data source being used (Koch and Dees, 2008): field measurement, remotely sensed data or ancillary data used in GIS-based modeling. Field measurements are based on destructive sampling or direct measurement and the application of allometric equations (Madgwick, 1994). Recently, remotely sensed data, from both passive and active sensors, have become an important data source for AGB estimation. In this chapter we will focus on the use of optical multispectral data such as TM/ETM+ to estimate AGB. Generally, biomass is either estimated via a direct relationship between spectral response and biomass using multiple regression, k-nearest neighbor, neural networks, inverse canopy models or through indirect relationships, whereby attributes estimated from the remotely sensed data, such as leaf area index (LAI), structure (crown closure and height) or shadow fraction are used in equations to estimate biomass (Wulder, 1998). Here, we discuss the use of remote sensing data of moderate spatial resolution as input to estimate AGB. Research has demonstrated that it is more effective to generate relationships between field measurements and moderate spatial resolution remotely sensed data (e.g., LANDSAT), and then extrapolate these relationships over larger areas using comparable spectral properties from coarser spatial resolution imagery (e.g., MODIS) (Steininger, 2000; Lu, 2005; Phua and Saito, 2003; Foddy el al., 2003; Fazakas et al., 1999; Roy and Ravan, 1996; Zheng et al., 2004; Mickler et al., 2002). In general terms, LANDSAT TM and ETM+ data are the most widely used data of remotely sensed imagery for forest biomass estimation, but data from other moderate spatial resolution sensors have also been used, including ASTER and HYPERION data. In this chapter we present approaches that are currently being developed in Chile. Specifically, we introduce methods for the estimation of AGB using medium spatial resolution satellite imagery and digital elevation models. The main objective is to create, calibrate and validate such methods for applications. We developed an alternative approach in the estimation of AGB using LANDSAT ETM + imagery and SRTM digital elevation models as covariates for geostatistical modeling. From the spatial perspective, AGB data correspond to an array of points in space (x, y), while covariates correspond to a set of data that has a large number of samples in geographic space (extracted from each pixel), some of which having overlap with the available AGB