Ecosystem state shifts during long-term development of an Amazonian peatland.

The most carbon (C)-dense ecosystems of Amazonia are areas characterized by the presence of peatlands. However, Amazonian peatland ecosystems are poorly understood and are threatened by human activities. Here, we present an investigation into long-term ecohydrological controls on C accumulation in an Amazonian peat dome. This site is the oldest peatland yet discovered in Amazonia (peat initiation ca. 8.9 ka BP), and developed in three stages: (i) peat initiated in an abandoned river channel with open water and aquatic plants; (ii) inundated forest swamp; and (iii) raised peat dome (since ca. 3.9 ka BP). Local burning occurred at least three times in the past 4,500 years. Two phases of particularly rapid C accumulation (ca. 6.6-6.1 and ca. 4.9-3.9 ka BP), potentially resulting from increased net primary productivity, were seemingly driven by drier conditions associated with widespread drought events. The association of drought phases with major ecosystem state shifts (open water wetland-forest swamp-peat dome) suggests a potential climatic control on the developmental trajectory of this tropical peatland. A third drought phase centred on ca. 1.8-1.1 ka BP led to markedly reduced C accumulation and potentially a hiatus during the peat dome stage. Our results suggest that future droughts may lead to phases of rapid C accumulation in some inundated tropical peat swamps, although this can lead ultimately to a shift to ombrotrophy and a subsequent return to slower C accumulation. Conversely, in ombrotrophic peat domes, droughts may lead to reduced C accumulation or even net loss of peat. Increased surface wetness at our site in recent decades may reflect a shift towards a wetter climate in western Amazonia. Amazonian peatlands represent important carbon stores and habitats, and are important archives of past climatic and ecological information. They should form key foci for conservation efforts.

Hydroecology of Amazonian lacustrine Arcellinida (testate amoebae): A case study from Lake Quistococha, Peru.

Organic rich sediments were obtained from seven core tops taken in Lake Quistococha, near the city of Iquitos in the Peruvian Amazon. Subsamples from 0 to 4cm depth in each core were analyzed under dissecting light microscopy to carry out the first investigation of Arcellinida (testate lobose amoebae) from a lacustrine environment in this ecologically important region. The fauna was characterized by a low diversity, low abundance community dominated by centropyxids. This fauna is similar to 'stressed' assemblages reported from temperate latitudes, except that test concentrations were two orders of magnitude lower than typical in temperate lakes. Principle arcellinidan stressors in Lake Quistococha likely include the low pH 4 conditions in the lake, and a general lack of suitable minerogenic material to construct tests in the organic rich lake substrate. The low pH conditions are the result of runoff and seepage of water high in dissolved organic carbon from the adjacent similarly low pH 4 terrestrial peatland. The dearth of minerogenic material is the result of the lake being isolated from riverine input for the past ∼2000 years, even during flooding events. Other limiting factors contributing to depressed arcellinidan populations may include nutrient supply, predation pressure, competition, and post-mortem taphonomic factors.

Induction of reactive oxygen species in bovine neutrophils is CD11b, but not dectin-1-dependent.

Neutrophils play a key role in initiating an innate immune response, being the first type of immune cell arriving at the site of injury or infection. These cells are able to mount a direct anti-bactericidal response by the production of reactive oxygen or reactive nitrogen species (ROS/RNS). An important component of the host innate immune response is recognition of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs). Toll-like receptors (TLRs) are an important family of PRRs and, are a key component in activation of innate immune mechanisms. In the present study we described the presence of mRNA transcripts for TLR1, TLR2, TLR4, TLR6, TLR7 and TLR10 in bovine neutrophils. In contrast, the presence of mRNA transcripts for TLR3 varied between animals, whereas no transcripts were detected for TLR5, TLR8, TLR9 or the C-type lectin receptor dectin-1 in neutrophils isolated from bovine blood. Additionally, zymosan, a dectin-1/TLR2 ligand, induced ROS, but not RNS production in a CD11b-, but not dectin-1-dependent manner. This effect was dependent on Store Operated Calcium Entry (SOCE), and partially inhibited using monoclonal antibodies to CD11b. Taken together, our data describe the presence of specific PRRs transcripts in the mRNA isolated from bovine neutrophil and show a CD11b-/Ca(2+) dependent ROS production by these cells.

Study of diet, biomarkers and cancer risk in the United States, China and Costa Rica.

One striking paradox in epidemiologic research is the strong association between diet and cancer in ecologic studies compared with the weaker associations reported in many within-country case-control and cohort studies. However, most ecologic studies have relied on indirect measures of dietary intake, such as food disappearance data. The objectives of our study were to assess the feasibility of collecting dietary and biomarker data from individuals living in countries having markedly different dietary patterns and cultures and to examine the magnitude of the between-country variation in their measurement. Adults surveyed in Shanghai (China), Costa Rica and King County (Washington, USA) completed a 24-hr dietary recall, a cancer risk factor survey, and provided a blood sample. We analyzed a subset of the blood specimens for vitamins C, E, carotenoids and phospholipid fatty acids. We observed substantial differences in nutrient intakes and in mean plasma concentrations of dietary biomarkers across the study populations. For example, King County participants had the highest daily intake of vitamin C (mean 78.3 +/- 12.2 mg compared with 42.6 +/- 38.3 mg in Shanghai and 34.8 +/- 43.8 mg in Costa Rica). The mean plasma vitamin C level in King County was also the highest of the 3 study sites: 927.9 +/- 43.9 microg/dl in King County, 585.7 +/- 35.9 microg/dl in Shanghai and 461.1 +/- 33.1 microg/dl in Costa Rica. Plasma trans fatty acids (a biomarker of a diet high in hydrogenated fats) were highest in King County and lowest in Shanghai.

A biomedical engineer's experience in Nicaragua.

The experiences of a 12-member team composed of physicians, nurses, a respiratory therapist, a rehabilitation engineer with specialty training in prosthetics and orthotics, and a biomedical engineer at a third-world medical facility are described. The obstacles encountered in the form of limited equipment, the state of disrepair of existing equipment, and environmental factors (heat and humidity) are discussed. The question of how best to help developing countries is examined.

Allergic bronchopulmonary aspergillosis in pediatric practice.

Twelve cases of allergic bronchopulmonary aspergillosis in the pediatric age group are reported. The average age of diagnosis was 14.5 years with a range from 6 to 18 years. All patients had a history of pulmonary infiltrations or atelectasis or both documented by chest radiographs. Eight patients had bronchograms or tomograms, and seven of them showed proximal bronchiectasis. Total serum IgE concentrations were elevated in all patients. Preciptitating antibodies against Aspergillus fumigatus were positive in all patients at the time of diagnosis, and became negative in some after therapy. The specific IgE or IgG antibody activity agaist Af was elevated in all 12 patients. After prednisone was started the total serum IgE sharply declined to a plateau and remained at this level until a flare of allergic aspergillosis occurred. A flare of allergic aspergillosis is characterized by an increasing total serum IgE concentration followed by pulmonary infiltration. Clinical and roentgenologic improvements were observed after steroid therapy. The importance and methods of early diagnosis in the pediatric population are discussed.

Immunologic responses to therapy in allergic bronchopulmonary aspergillosis: serum IgE value as an indicator and predictor of disease activity.

Two patients, a child and an adult, with allergic bronchopulmonary aspergillosis were studied over an 18-month period. Initially elevated total serum IgE levels fell during prednisone therapy and rose prior to and during an exacerbation. Total serum IgG fell with therapy, whereas the values of IgA and IgM remained constant. Specific IgG and IgE values against Aspergillus fumigatus as measured by radioimmunoassay were elevated in both patients. Specific IgE values increased in each patient prior to exacerbation, whereas specific IgG values increased in only one patient at the time of exacerbation. Immunologic evaluation may provide an assessment of disease activity of prospective value.

Hyperimmunoglobulinemia E in a child with allergic bronchopulmonary aspergillosis and bronchiectasis.

A 12-year-old boy was hospitalized for resection of a bronchiectatic lesion. Investigation of an elevated cencentration of serum IgE led to a diagnosis of allergic bronchopulmonary aspergillosis. ABPA has rarely been described in the pediatric age group. This hypersensitivity lung disease is characterized by intermittent wheezing, fever, recurrent pulmonary infiltrates, eosinophilia, hyperimmunoglobulinemia E, and Type I (allergic) skin reactivity to aspergillus extract. Hyphae of aspergillus may also be found in expectorated brown mucus plugs. Type III (Arthus) skin test response and presence of precipitating antibody to this fungus may be demonstrated. Central bronchiectasis or pulmonary fibrosis may result from uncontrolled progression of this disease.