Limiting factors for phytoplankton growth in subtropical reservoirs: the effect of light and nutrient availability in different longitudinal compartments

Limited information is available on the interactions between environmental factors and algal growth in tropical and subtropical aquatic systems. We investigated the relationships between algal biomass (measured as chlorophyll, Chl-a) and light, total phosphorus (TP) and total nitrogen (TN) in longitudinal zones of subtropical reservoirs. We studied the seasonal variation of water variables in Itupararanga Reservoir (Brazil) and compared the results with 16 other subtropical lakes and reservoirs. The longitudinal zones in Itupararanga Reservoir were considered statistically different (p 0.05, MANOVA). From the riverine zone to the dam region of the reservoir, Spearman Correlation Test suggested that light limitation and TP limitation tended to decrease and increase, respectively. Although nitrate concentrations were high (400 g/L), the Spearman coefficients between Chl-a and TN and the TN:TP ratios (11:1 TN:TP 35:1) indicated that nitrogen may be co-limiting algal growth in the studied water body. Putting Itupararanga in a regional context allowed assessment of potential influences of land use on trophic state. Within the subtropical dataset, TP explained a greater percentage of variance in Chl-a (R2 = 0.70) than TN (R2 = 0.17). The main land use type within the reservoirs drainage area significantly influenced the concentrations of TP, TN, and Chl-a (p 0.05, MANOVA), with different relationships between nutrients and chlorophyll in forested (R2 = 0.12-0.33), agricultural (R2 = 0.50-0.68) and urban (R2 = 0.09-0.64) watersheds. Comparisons with literature values and those from reservoirs with less altered watersheds indicated that Itupararanga Reservoir is reaching the mesotrophic-eutrophic boundary, and further nutrient enrichment could cause water quality degradation.

The effectiveness of Eucalyptus barrier in containing the edge effect on a subtropical forest fragment in the state of Sao Paulo, Brazil

Edge effects resulting from isolation and subsequent microclimatic changes are one of the most important threats to the forest fragments conservation. The efficiency of maintaining a barrier formed by three rows of Eucalyptus along the edge of a subtropical seasonal semi deciduous forest fragment, surrounded by Eucalyptus monoculture, was evaluated as a way of softening the microclimatic changes (light intensity, temperature and relative humidity) and the impacts of eucalypt mechanized harvesting on the native vegetation along the contact zone between the forest fragment and the plantation. The Eucalyptus barrier was effective in softening the microclimate. Light intensity was 35% lower in the presence of the barrier. The barrier also provided a reduction of 1 C in air temperature and increased in 3.4% in relative humidity throughout the year. The barrier was also effective in preventing the impact on native vegetation, avoiding damage to adult trees and preserving the regenerating forest stratum near the border, which was reduced to less than 20% in density and 50% in richness, with no such barrier. The barrier of Eucalyptus may, therefore, be recommended as an effective method to minimize the impacts of mechanized forest harvesting operations and mitigate the microclimatic conditions along the edge of forest fragments.

Brazilian Propolis: Seasonal Variation of the Prenylated p-Coumaric Acids and Antimicrobial Activity

Brazilian green propolis, which is used in food and beverages to improve health and to prevent diseases, demostrates antioxidant, antimutagenic, and antimicrobial activities. Most biological activities are thought to be related to the high levels of drupanin, artepillin C, and baccharin, which are compounds also present in Baccharis dracunculifolia D.C. (Asteraceae). Since propolis chemical composition depends on the region and the period of collection, as well as its plant origin, the effect of seasonal variation on the both content of prenylated p-coumaric acids and in vitro antimicrobial activity of Brazilian propolis from four different sites, was performed. The results showed that MIC values ranged from 100 to 300 mu g/mL against both Staphylococcus aureus and Kocuria rhizophila, while none of the propolis samples was active against Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. HPLC analysis showed that the content of drupanin, artepillin C, and baccharin varied throughout the year, as well as among the different study sites. Also, it is suggested that Baccharis dracunculifolia is the main botanical source of Brazilian propolis in sites I and 2, while in sites 3 and 4, other plant species are also used by bees to produce propolis. All the evaluated propolis samples exhibited similar antibacterial activity, but different contents of prenylated p-coumaric acids throughout the year.

Analysis of long-term light-trap data for Helicoverpa spp. (Lepidoptera : Noctuidae) in Australia: the effect of climate and crop host plants

Regression analyses of a long series of light-trap catches at Narrabri, Australia, were used to describe the seasonal dynamics of Helicoverpa armigera (Hubner). The size of the second generation was significantly related to the size of the first generation, to winter rainfall, which had a positive effect, and to spring rainfall which had a negative effect. These variables accounted for up to 96% of the variation in size of the second generation from year to year. Rainfall and crop hosts were also important for the size of the third generation. The area and tonnage of many potential host crops were significantly correlated with winter rain. When winter rain was omitted from the analysis, the sizes of both the second and third generations could be expressed as a function of the size of the previous generation and of the areas planted to lucerne, sorghum and maize. Lucerne and maize always had positive coefficients and sorghum a negative one. We extended our analysis to catches of H. punctigera (Wallengren), which declines in abundance after the second generation. Winter rain had a positive effect on the sizes of the second and third generations, and rain in spring or early summer had a negative effect. Only the area grown to lucerne had a positive effect on abundance. Forecasts of pest levels from a few months to a few weeks in advance are discussed, along with the improved understanding of the seasonal dynamics of both species and the significance of crops in the management of insecticide resistance for H. armigera.

The effect of heat transfer mode on heart rate responses and hysteresis during heating and cooling in the estuarine crocodile Crocodylus porosus

The effect of heating and cooling on heart rate in the estuarine crocodile Crocodylus porosus was studied in response to different heat transfer mechanisms and heat loads. Three heating treatments were investigated. C. porosus were: (1) exposed to a radiant heat source under dry conditions; (2) heated via radiant energy while half-submerged in flowing water at 23degreesC and (3) heated via convective transfer by increasing water temperature from 23degreesC to 35degreesC. Cooling was achieved in all treatments by removing the heat source and with C. porosus half-submerged in flowing water at 23degreesC. In all treatments, the heart rate of C. porosus increased markedly in response to heating and decreased rapidly with the removal of the heat source. Heart rate during heating was significantly faster than during cooling at any given body temperature, i.e. there was a significant heart rate hysteresis. There were two identifiable responses to heating and cooling. During the initial stages of applying or removing the heat source, there was a dramatic increase or decrease in heart rate ('rapid response'), respectively, indicating a possible cardiac reflex. This rapid change in heart rate with only a small change or no change in body temperature (

Evaluation of temporal, seasonal and geographic stability of the molluscicidal property of Euphorbia splendens latex

Laboratory tests with aqueous solutions of Euphorbia splendens var. hislopii latex have demonstrated seasonal stability of the molluscicidal principle, with LD90 values of 1.14 ppm (spring), 1.02 ppm (fall), 1.09 ppm (winter), and 1.07 ppm (summer) that have been determined against Biomphalaria tenagophila in the field. Assays on latex collected in Belo Horizonte and Recife yielded LD90 values similar to those obtained with the reference substance collected in Rio de Janeiro (Ilha do Governador), demonstrating geographic stability of the molluscicidal effect. The molluscicidal action of aqueous dilutions of the latex in natura, centrifuged (precipitate) and lyophilized, was stable for up to 124 days at room temperature (in natura) and for up to 736 days in a common refrigerator at 10 to 12ºC (lyophilized product). A 5.0 ppm solution is 100% lethal for snails up to 13 days after preparation, the effect being gradually lost to almost total inactivity by the 30th day. This observation indicated that the active principle is instable. These properties together with the wide distribution of the plant, its resistance and adaptation to the tropical climate, its easy cultivation and the easy obtention of latex and preparation of the molluscicidal solution, make this a promising material for large-scale use in the control of schistosomiasis

Variability of North Atlantic hurricanes: seasonal versus individual-event features

Tropical cyclones are affected by a large number of climatic factors, which translates into complex patterns of occurrence. The variability of annual metrics of tropical-cyclone activity has been intensively studied, in particular since the sudden activation of the North Atlantic in the mid 1990’s. We provide first a swift overview on previous work by diverse authors about these annual metrics for the North-Atlantic basin, where the natural variability of the phenomenon, the existence of trends, the drawbacks of the records, and the influence of global warming have been the subject of interesting debates. Next, we present an alternative approach that does not focus on seasonal features but on the characteristics of single events [Corral et al., Nature Phys. 6, 693 (2010)]. It is argued that the individual-storm power dissipation index (PDI) constitutes a natural way to describe each event, and further, that the PDI statistics yields a robust law for the occurrence of tropical cyclones in terms of a power law. In this context, methods of fitting these distributions are discussed. As an important extension to this work we introduce a distribution function that models the whole range of the PDI density (excluding incompleteness effects at the smallest values), the gamma distribution, consisting in a powerlaw with an exponential decay at the tail. The characteristic scale of this decay, represented by the cutoff parameter, provides very valuable information on the finiteness size of the basin, via the largest values of the PDIs that the basin can sustain. We use the gamma fit to evaluate the influence of sea surface temperature (SST) on the occurrence of extreme PDI values, for which we find an increase around 50 % in the values of these basin-wide events for a 0.49 C SST average difference. Similar findings are observed for the effects of the positive phase of the Atlantic multidecadal oscillation and the number of hurricanes in a season on the PDI distribution. In the case of the El Niño Southern oscillation (ENSO), positive and negative values of the multivariate ENSO index do not have a significant effect on the PDI distribution; however, when only extreme values of the index are used, it is found that the presence of El Niño decreases the PDI of the most extreme hurricanes.

Oseltamivir in seasonal, avian H5N1 and pandemic 2009 A/H1N1 influenza: pharmacokinetic and pharmacodynamic characteristics.

Oseltamivir is the ester-type prodrug of the neuraminidase inhibitor oseltamivir carboxylate. It has been shown to be an effective treatment for both seasonal influenza and the recent pandemic 2009 A/H1N1 influenza, reducing both the duration and severity of the illness. It is also effective when used preventively. This review aims to describe the current knowledge of the pharmacokinetic and pharmacodynamic characteristics of this agent, and to address the issue of possible therapeutic drug monitoring. According to the currently available literature, the pharmacokinetics of oseltamivir carboxylate after oral administration of oseltamivir are characterized by mean ± SD bioavailability of 79 ± 12%, apparent clearance of 25.3 ± 7.0 L/h, an elimination half-life of 7.4 ± 2.5 hours and an apparent terminal volume of distribution of 267 ± 122 L. A maximum plasma concentration of 342 ± 83 μg/L, a time to reach the maximum plasma concentration of 4.2 ± 1.1 hours, a trough plasma concentration of 168 ± 32 μg/L and an area under the plasma concentration-time curve from 0 to 24 hours of 6110 ± 1330 μg · h/L for a 75 mg twice-daily regimen were derived from literature data. The apparent clearance is highly correlated with renal function, hence the dosage needs to be adjusted in proportion to the glomerular filtration rate. Interpatient variability is moderate (28% in apparent clearance and 46% in the apparent central volume of distribution); there is no indication of significant erratic or limited absorption in given patient subgroups. The in vitro pharmacodynamics of oseltamivir carboxylate reveal wide variation in the concentration producing 50% inhibition of influenza A and B strains (range 0.17-44 μg/L). A formal correlation between systemic exposure to oseltamivir carboxylate and clinical antiviral activity or tolerance in influenza patients has not yet been demonstrated; thus no formal therapeutic or toxic range can be proposed. The pharmacokinetic parameters of oseltamivir carboxylate after oseltamivir administration (bioavailability, apparent clearance and the volume of distribution) are fairly predictable in healthy subjects, with little interpatient variability outside the effect of renal function in all patients and bodyweight in children. Thus oseltamivir carboxylate exposure can probably be controlled with sufficient accuracy by thorough dosage adjustment according to patient characteristics. However, there is a lack of clinical study data on naturally infected patients. In addition, the therapeutic margin of oseltamivir carboxylate is poorly defined. The usefulness of systematic therapeutic drug monitoring in patients therefore appears to be questionable; however, studies are still needed to extend the knowledge to particular subgroups of patients or dosage regimens.

Effect of Lactobacillus paracasei ST11 on a nasal provocation test with grass pollen in allergic rhinitis.

Cite this as: J. Wassenberg, S. Nutten, R. Audran, N. Barbier, V. Aubert, J. Moulin, A. Mercenier and F. Spertini, Clinical & Experimental Allergy, 2011 (41) 565-573. SUMMARY: Background Probiotics have been associated with prevention and improvement of symptoms in atopic diseases such as atopic dermatitis. However, few studies exist that document their efficacy for upper airways allergies such as allergic rhinitis. Objective To investigate the effect of short-term oral administration of Lactobacillus paracasei ST11 on a nasal provocation test (NPT) with grass pollen. Methods Thirty-one adult volunteers with allergic rhinitis were enrolled in a randomized, double-blind, placebo-controlled study, based on two 4-week cross-over periods of product consumption (ST11-fermented milk vs. placebo), separated by a wash-out period of 6-8 weeks. Objective and subjective clinical parameters of NPT as well as systemic and nasal immunological parameters were compared between the two treatment periods (registration number: NCT 011 50 253). Results Subjects that received ST11-fermented milk had lower nasal congestion than subjects under placebo (visual analogical scale; P<0.05). Nasal pruritus followed the same trend. However, no significant change in combined nasal reaction threshold was observed between the two periods. IL-5 secretion by peripheral blood mononuclear cells and serum allergen-specific IgG4 were significantly lower in ST11-fermented milk group compared to placebo group. IL-8 and IL-10 secretion followed the same trend. Conclusion and Clinical Relevance Short-term treatment with ST11-fermented milk before NPT significantly improved a clinical marker of NPT (subjective nasal congestion) and down-regulated systemic immune markers (IL-5 from peripheral blood mononuclear cells and serum IgG4). These data strongly suggest that probiotics may down modulate key parameters of allergic rhinitis and warrant future evaluation in seasonal trials.

The Effect of Four-Lane to Three-Lane Conversion on the Number of Crashes and Crash Rates in Iowa Roads, June 2005

We analyze crash data collected by the Iowa Department of Transportation using Bayesian methods. The data set includes monthly crash numbers, estimated monthly traffic volumes, site length and other information collected at 30 paired sites in Iowa over more than 20 years during which an intervention experiment was set up. The intervention consisted in transforming 15 undivided road segments from four-lane to three lanes, while an additional 15 segments, thought to be comparable in terms of traffic safety-related characteristics were not converted. The main objective of this work is to find out whether the intervention reduces the number of crashes and the crash rates at the treated sites. We fitted a hierarchical Poisson regression model with a change-point to the number of monthly crashes per mile at each of the sites. Explanatory variables in the model included estimated monthly traffic volume, time, an indicator for intervention reflecting whether the site was a “treatment” or a “control” site, and various interactions. We accounted for seasonal effects in the number of crashes at a site by including smooth trigonometric functions with three different periods to reflect the four seasons of the year. A change-point at the month and year in which the intervention was completed for treated sites was also included. The number of crashes at a site can be thought to follow a Poisson distribution. To estimate the association between crashes and the explanatory variables, we used a log link function and added a random effect to account for overdispersion and for autocorrelation among observations obtained at the same site. We used proper but non-informative priors for all parameters in the model, and carried out all calculations using Markov chain Monte Carlo methods implemented in WinBUGS. We evaluated the effect of the four to three-lane conversion by comparing the expected number of crashes per year per mile during the years preceding the conversion and following the conversion for treatment and control sites. We estimated this difference using the observed traffic volumes at each site and also on a per 100,000,000 vehicles. We also conducted a prospective analysis to forecast the expected number of crashes per mile at each site in the study one year, three years and five years following the four to three-lane conversion. Posterior predictive distributions of the number of crashes, the crash rate and the percent reduction in crashes per mile were obtained for each site for the months of January and June one, three and five years after completion of the intervention. The model appears to fit the data well. We found that in most sites, the intervention was effective and reduced the number of crashes. Overall, and for the observed traffic volumes, the reduction in the expected number of crashes per year and mile at converted sites was 32.3% (31.4% to 33.5% with 95% probability) while at the control sites, the reduction was estimated to be 7.1% (5.7% to 8.2% with 95% probability). When the reduction in the expected number of crashes per year, mile and 100,000,000 AADT was computed, the estimates were 44.3% (43.9% to 44.6%) and 25.5% (24.6% to 26.0%) for converted and control sites, respectively. In both cases, the difference in the percent reduction in the expected number of crashes during the years following the conversion was significantly larger at converted sites than at control sites, even though the number of crashes appears to decline over time at all sites. Results indicate that the reduction in the expected number of sites per mile has a steeper negative slope at converted than at control sites. Consistent with this, the forecasted reduction in the number of crashes per year and mile during the years after completion of the conversion at converted sites is more pronounced than at control sites. Seasonal effects on the number of crashes have been well-documented. In this dataset, we found that, as expected, the expected number of monthly crashes per mile tends to be higher during winter months than during the rest of the year. Perhaps more interestingly, we found that there is an interaction between the four to three-lane conversion and season; the reduction in the number of crashes appears to be more pronounced during months, when the weather is nice than during other times of the year, even though a reduction was estimated for the entire year. Thus, it appears that the four to three-lane conversion, while effective year-round, is particularly effective in reducing the expected number of crashes in nice weather.

Comparison of two oral probiotic preparations in a randomized crossover trial highlights a potentially beneficial effect of Lactobacillus paracasei NCC2461 in patients with allergic rhinitis.

BACKGROUND: There is promising but conflicting evidence to recommend the addition of probiotics to foods for prevention and treatment of allergy. Based on previous studies with fermented milk containing Lactobacillus paracasei NCC2461, we aimed to compare the effect of a powder form of the latter probiotic with the effect of a blend of Lactobacillus acidophilus ATCC SD5221 and Bifidobacterium lactis ATCC SD5219 in patients with allergic rhinitis. METHODS: A double-blind, randomized, cross-over study, involving 31 adults with allergic rhinitis to grass pollen, was performed outside the grass pollen season (registration number: NCT01233154). Subjects received each product for 4-weeks in two phases separated by a wash-out period of 6 to 8 weeks. A nasal provocation test was performed before and after each 4-week product intake period, and outcome parameters (objective and subjective clinical symptoms; immune parameters) were measured during and/or 24 hours after the test. RESULTS: Out of the 31 subject enrolled, 28 completed the study. While no effect was observed on nasal congestion (primary outcome), treatment with NCC2461 significantly decreased nasal pruritus (determined by VAS), and leukocytes in nasal fluid samples, enhanced IL-5, IL-13 and IL-10 production by peripheral blood mononuclear cells in an allergen specific manner and tended to decrease IL-5 secretion in nasal fluid, in contrast to treatment with the blend of L. acidophilus and B. lactis. CONCLUSIONS: Despite short-term consumption, NCC2461 was able to reduce subjective nasal pruritus while not affecting nasal congestion in adults suffering from grass pollen allergic rhinitis. The associated decrease in nasal fluid leukocytes and IL-5 secretion, and the enhanced IL-10 secretion in an allergen specific manner may partly explain the decrease in nasal pruritus. However, somewhat unexpected systemic immune changes were also noted. These data support the study of NCC2461 consumption in a seasonal clinical trial to further demonstrate its potentially beneficial effect.

Seasonal dependence in the solar neutrino flux

Mikheyev-Smirnov-Wolfenstein (MSW) solutions of the solar neutrino problem predict a seasonal dependence of the zenith angle distribution of the event rates, due to the nonzero latitude at the Super-Kamiokande site. We calculate this seasonal dependence and compare it with the expectations in the no-oscillation case as well as just-so scenario, in the light of the latest Super-Kamiokande 708-day data. The seasonal dependence can be sizable in the large mixing angle MSW solution and would be correlated with the day-night effect. This may be used to discriminate between MSW and just-so scenarios and should be taken into account in refined fits of the data.

EFFECT OF WATER AVAILABILITY ON SOIL MICROBIAL BIOMASS IN SECONDARY FOREST IN EASTERN AMAZONIA

Soil microbial biomass (SMB) plays an important role in nutrient cycling in agroecosystems, and is limited by several factors, such as soil water availability. This study assessed the effects of soil water availability on microbial biomass and its variation over time in the Latossolo Amarelo concrecionário of a secondary forest in eastern Amazonia. The fumigation-extraction method was used to estimate the soil microbial biomass carbon and nitrogen content (SMBC and SMBN). An adaptation of the fumigation-incubation method was used to determine basal respiration (CO2-SMB). The metabolic quotient (qCO2) and ratio of microbial carbon:organic carbon (CMIC:CORG) were calculated based on those results. Soil moisture was generally significantly lower during the dry season and in the control plots. Irrigation raised soil moisture to levels close to those observed during the rainy season, but had no significant effect on SMB. The variables did not vary on a seasonal basis, except for the microbial C/N ratio that suggested the occurrence of seasonal shifts in the structure of the microbial community.

Effect of sex and seasons of the year on hematologic and serum biochemical variables of captive brown brocket deer (Mazama gouazoubira)

The Brown brocket deer (Mazama gouazoubira) is the most common free-living and captive deer in South America, especially in Brazil, and has great ecological and scientific significance. However, data on hematological and biochemical parameters in brown brocket deer are scarce. The goal of this study was to establish reference ranges for hematological and biochemical parameters of Mazama gouazoubira, comparing differences during the seasons of the year and between sex. Blood samples from ten adult healthy brown brocket deer (6 female and 4 male) were collected during daytime, monthly, during 12 months. The animals were maintained in individual stable, protected from noise and fed ad libitum with commercial ration and green fodder. For blood collection, animals were submitted to physical restrain for no longer than 2 minutes. The following parameters were determined: red blood cell count (RBC), haemoglobin concentration, packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), white blood cell count (WBC), platelet count, enzyme activity of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT) and serum levels of alkaline phosphatase (ALP), creatine kinase (CK), total protein (TP), albumin, cholesterol, total calcium, ionic calcium, sodium, potassium, magnesium, triglycerides, creatinine and urea. Values were compared according to season and sex. RBC count, WBC count and MCV suggested seasonal influence. Haemoglobin concentration, PCV and MCV were influenced by sex. Serum concentration of total calcium, ionic calcium, sodium, potassium and magnesium were influenced by season. Serum magnesium was also influenced by sex. The blood parameters herein reported may be useful as reference values for diagnostic and prognostic purposes in captive brown-brocket deer.

The effect of sun exposure on 25-hydroxyvitamin D concentrations in young healthy subjects living in the city of São Paulo, Brazil

The range of 25-hydroxyvitamin D (25OHD) concentration was determined in a young healthy population based on bone metabolism parameters and environmental and behavioral aspects. We studied 121 healthy young volunteers (49 men, 72 women) living in São Paulo (23º 34' south latitude) belonging to three occupational categories: indoor workers (N = 28), medical school students (N = 44), and resident physicians (N = 49). Fasting morning blood samples were collected once from each volunteer from August 2002 to February 2004, and 25OHD, total calcium, albumin, alkaline phosphatase, phosphorus, creatinine, intact parathyroid hormone, osteocalcin, and type I collagen carboxyterminal telopeptide were measured. Data are reported as means ± SD. Mean subject age was 24.7 ± 2.68 years and mean 25OHD level for the entire group was 78.7 ± 33.1 nM. 25OHD levels were lower (P < 0.05) among resident physicians (67.1 ± 27.0 nM) than among students (81.5 ± 35.8 nM) and workers (94.0 ± 32.6 nM), with the last two categories displaying no difference. Parathyroid hormone was higher (P < 0.05) and osteocalcin was lower (P < 0.05) among resident physicians compared to non-physicians. Solar exposure and frequency of beach outings showed a positive association with 25OHD (P < 0.001), and summer samples presented higher results than winter ones (97.8 ± 33.5 and 62.9 ± 23.5 nM, respectively). To define normal levels, parameters such as occupational activity, seasonality and habits related to solar exposure should be taken into account. Based on these data, we considered concentrations above 74.5 nM to be desired optimal 25OHD levels, which were obtained during the summer for 75% of the non-physicians.