Integrating network pharmacology approach and experimental validation to reveal the alleviation of Shenkangning capsule on chronic nephritis.

ETHNOPHARMACOLOGICAL RELEVANCE: Shenkangning (SKN), a Chinese patent medicine composed by eight Chinese medicinal herbs, is commonly applied to treat chronic glomerulonephritis (CGN) in clinic. However, its mechanism is still not clear now. AIM OF THE STUDY: This study is designed to evaluate the SKN-provided alleviation on adriamycin (ADR)-induced nephropathy, to reveal its mechanism by integrating network pharmacology analysis and experimental evidences, and to further find the main drug that makes a major contribution to its efficacy. MATERIALS AND METHODS: ADR was intravenously injected to mice to induce focal segmental glomerulosclerosis (FSGS). Renal histological evaluation was conducted. The level of urinary protein, and serum amounts of creatinine, urea nitrogen (BUN) and albumin were detected. The potential mechanisms were predicted by network pharmacology analysis and further validated by Real-time polymerase chain reaction (RT-PCR), Western-blot and enzyme-linked immunosorbent assay (ELISA). RESULTS: SKN (1, 10 g/kg) improved ADR-induced nephropathy in mice. Network pharmacology results predicted that inflammation and oxidative stress were crucially involved in the SKN-provided amelioration on nephropathy. SKN reduced the activation of nuclear factor-κB (NF-κB) and the expression of some pro-inflammatory cytokines, and increased the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) and the expression of its downstream genes in ADR-induced nephropathy in mice. Furthermore, SKN also restored the reduced expression of both podocin and synaptopodin, which are podocyte-associated proteins. Further results showed that the toxic drug Danfupian (DFP) had no contribution to the SKN-provided alleviation on ADR-induced nephropathy in mice. After integrating the results from evaluating anti-inflammation, anti-oxidant and anti-injury of podocytes in vitro and from comparing the activity of the whole SKN and SKN without Astragali Radix (Huangqi, HQ) in vivo, we found that HQ played a crucial contribution to the SKN-provided amelioration on ADR-induced nephropathy in mice. CONCLUSION: SKN improved ADR-induced nephropathy through suppressing renal inflammation and oxidative stress injury via abrogating NF-κB activation and activating Nrf2 signaling pathway. HQ played a main contribution to the SKN-provided amelioration on ADR-induced nephropathy.

Ellagic acid protects type II collagen induced arthritis in rat via diminution of IKB phosphorylation and suppression IKB-NF-kB complex activation: in vivo and in silico study.

OBJECTIVE: The present study was designed to explore the potential anti-inflammatory and anti-arthritic effects of ellagic acid (EA) in collagen-induced arthritis (CIA). METHODS: CIA rats were treated with MTX (0.25 mg/kg body wt.) and EA (50 mg/kg b.wt.) for a period of 20 days. The effects of treatment in the rats were assessed biochemically by analyzing inflammatory mediators (NF-kB, iNOS, TNF-α, IL-1ß, IL-6 and IL-10) and oxidative stress related parameters (MPO, NO, LPO, catalase, SOD, GSH). In addition, we also assessed the expression of some inflammatory mediators TNF-α, CD8 + though immunohistochemistry in the joint tissue. RESULTS: In the present study, we found expression and synthesis of transcription factor NF-kB was prominent in CIA rats. In addition, main pro-inflammatory cytokines such as TNF-α, IL-1ß, IL-6, and the anti-inflammatory IL-10, was also stand out. Further, reactive oxygen/nitrogen species was also elevated in CIA rats. Treatment with EA ameliorates all the above mentioned inflammatory and oxidative stress related parameters to near normal. Further, we also confirmed the expression of TNF-α, CD8+ T cells through immunohistochemistry was mitigates in joint tissue of EA treated rats. We find EA significantly inhibited the developmental phase of arthritis. CONCLUSION: These results suggest that EA act as potent anti-arthritic and anti-inflammatory agent that could be used as a tool for the development of new drug for the treatment of arthritis.

Environmental impacts of nitrogen emissions in China and the role of policies in emission reduction.

Atmospheric reactive nitrogen (Nr) has been a cause of serious environmental pollution in China. Historically, China used too little Nr in its agriculture to feed its population. However, with the rapid increase in N fertilizer use for food production and fossil fuel consumption for energy supply over the last four decades, increasing gaseous Nr species (e.g. NH3 and NOx) have been emitted to the atmosphere and then deposited as wet and dry deposition, with adverse impacts on air, water and soil quality as well as plant biodiversity and human health. This paper reviews the issues associated with this in a holistic way. The emissions, deposition, impacts, actions and regulations for the mitigation of atmospheric Nr are discussed systematically. Both NH3 and NOx make major contributions to environmental pollution but especially to the formation of secondary fine particulate matter (PM2.5), which impacts human health and light scattering (haze). In addition, atmospheric deposition of NH3 and NOx causes adverse impacts on terrestrial and aquatic ecosystems due to acidification and eutrophication. Regulations and practices introduced by China that meet the urgent need to reduce Nr emissions are explained and resulting effects on emissions are discussed. Recommendations for improving future N management for achieving 'win-win' outcomes for Chinese agricultural production and food supply, and human and environmental health, are described. This article is part of a discussion meeting issue 'Air quality, past present and future'.

Decision support system for NPK fertilization: a solution method for minimizing the impact on human health, climate change, ecosystem quality and resources.

Sugarcane cultivation requires correct fertilizer rates. However, when nutrients are not available, or there is over-fertilization, the yields are significantly reduced and the environmental burden increase. In this study, it is proposed a decision support system (DSS) for the correct NPK (nitrogen, phosphorus and potassium) fertilization. The DSS consists of two fuzzy models; the edaphic condition model (EDC-M) and the NPK fertilization model (NPK-M). The DSS using parameters from soil analysis and is based on the experience of two groups of experts to avoid the bias to the reality of a single group of professionals. The results of the DSS are compared with the results of soil analysis and those of the group of experts. One hundred and sixty tests were developed in the NPK-M. The N rate shows R 2=0.981 for the DSS and R 2=0.963 for soil analyzes. The P rate shows R 2=0.9702 for the DSS and R 2=0.9183 for the soil analyzes. The K rate shows R 2=0.9691 for the DSS and R 2=0.9663 for the soil analyzes. Environmental results indicate that the estimated rates with the DSS do reduce the environmental impact on the tests performed.

Prophylaxis of mitochondrial dysfunction caused by cellular decompression from hyperbaric exposure.

Mitochondrial dysfunction occurring in response to cellular perturbations can include altered mitochondrial motility and bioenergetic function having intracellular heterogeneity. Exogenous mitochondrial directed therapy may correct these dysfunctions. Using in vitro approaches, we find that cell perturbations induced by rapid decompression from hyperbaric conditions with specific gas exposures has differential effects on mitochondrial motility, inner membrane potential, cellular respiration, reactive oxygen species production, impaired maintenance of cell shape and altered intracellular distribution of bioenergetic capacity in perinuclear and cell peripheral domains. Addition of a first-generation cell-permeable succinate prodrug to support mitochondrial function has positive overall effects in blunting the resultant bioenergy responses. Our results with this model of perturbed cell function induced by rapid decompression indicate that alterations in bioenergetic state are partitioned within the cell, as directly assessed by a combination of mitochondrial respiration and dynamics measurements. Reductions in the observed level of dysfunction produced can be achieved with application of the cell-permeable succinate prodrug.

Dietary yeast hydrolysate and brewer's yeast supplementation could enhance growth performance, innate immunity capacity and ammonia nitrogen stress resistance ability of Pacific white shrimp (Litopenaeus vannamei).

An 8-week feeding trial was conducted to evaluate the effects of dietary yeast hydrolysate and brewer's yeast supplementation on growth, immune-related genes expression and ammonia nitrogen stress resistance of Pacific white shrimp (Litopenaeus vannamei). Three isonitrogenous and isolipidic practical diets were formulated to contain 0% (control diet), 1% yeast hydrolysate and 1% brewer's yeast, respectively. 360 juvenile L. vannamei with an initial weight (0.88 ±â€¯0.01 g) was randomly divided into 3 treatments in four replicates (30 shrimp per replicate). The results indicated that shrimp fed the diet containing 1% yeast hydrolysate had a significantly higher weight gain (WG), and specific growth rate (SGR) than that fed the control diet, and the lowest feed conversion ratio (FCR) was occurred in the 1% yeast hydrolysate supplementation group. Proximate composition in whole body and muscle among all treatments was not significantly influenced by the dietary yeast hydrolysate or brewer's yeast supplementation. The challenge test with ammonia nitrogen showed that lower cumulative survival was observed in those fed the control diet, and the highest cumulative survival was occurred at shrimp fed the 1% yeast hydrolysate supplementation. Shrimp fed the control diet had higher inflammation-related genes expression levels of tnf-α and il-1ß in the intestine than those fed the diets supplemented with 1% yeast hydrolysate or 1% brewer's yeast, however, there was no significant difference in expression level of alp in intestine among all treatments. The relative expression levels of mTOR signal pathway genes (eif4ebp, eif4e1a, eif4e2 and p70s6k) were significantly up-regulated in the shrimp fed the diets supplemented with 1% yeast hydrolysate, and the lowest gene expression levels of eif4ebp, eif4e1a, eif4e2 and p70s6k in the intestine were occurred at the control diet. The highest expression levels of the immune-related genes (dorsal, relish, and proPO) in the intestine were observed at shrimp fed the 1% yeast hydrolysate supplementation, and the lowest expression levels of these genes were occurred at shrimp fed the control diet, however, there was no significant difference in gene expression of lysozyme among all treatments. The expression levels of penaeidin3a, crustin, proPO, and IMD in the hepatopancreas were significantly influenced by the dietary yeast hydrolysate, brewer's yeast or no yeast product supplementation, shrimp fed the 1% yeast hydrolysate supplementation had higher expression levels of these genes than those fed the control diet. The present study indicated that dietary 1% yeast hydrolysate or brewer's yeast supplementation could improve growth performance, enhance innate immunity, and strengthen resistance of ammonia nitrogen stress, and dietary 1% yeast hydrolysate supplementation provides better immunostimulatory effects than brewer's yeast of L. vannamei.

Higher Fertilizer Inputs Increase Fitness Traits of Brown Planthopper in Rice.

Rice (Oryza sativa L.) is the primary staple food source for more than half of the world's population. In many developing countries, increased use of fertilizers is a response to increase demand for rice. In this study, we investigated the effects of three principal fertilizer components (nitrogen, phosphorus and potassium) on the development of potted rice plants and their effects on fitness traits of the brown planthopper (BPH) [Nilaparvata lugens (Stål) (Homoptera: Delphacidae)], which is a major pest of rice in Bangladesh and elsewhere. Compared to low fertilizer inputs, high fertilizer treatments induced plant growth but also favored BPH development. The BPH had higher survival, developed faster, and the intrinsic rate of natural increase (r m ) was higher on well-fertilized than under-fertilized plants. Among the fertilizer inputs, nitrogen had the strongest effect on the fitness traits of BPH. Furthermore, both the "Plant vigor hypothesis" and the "Plant stress hypothesis" were supported by the results, the former hypothesis more so than the latter. These hypotheses suggest that the most suitable/attractive hosts for insect herbivores are the most vigorous plants. Our findings emphasized that an exclusive focus on yield increases through only enhanced crop fertilization may have unforeseen, indirect, effects on crop susceptibility to pests, such as BPH.

Cyanobacterial Toxins of the Laurentian Great Lakes, Their Toxicological Effects, and Numerical Limits in Drinking Water.

Cyanobacteria are ubiquitous phototrophic bacteria that inhabit diverse environments across the planet. Seasonally, they dominate many eutrophic lakes impacted by excess nitrogen (N) and phosphorus (P) forming dense accumulations of biomass known as cyanobacterial harmful algal blooms or cyanoHABs. Their dominance in eutrophic lakes is attributed to a variety of unique adaptations including N and P concentrating mechanisms, N2 fixation, colony formation that inhibits predation, vertical movement via gas vesicles, and the production of toxic or otherwise bioactive molecules. While some of these molecules have been explored for their medicinal benefits, others are potent toxins harmful to humans, animals, and other wildlife known as cyanotoxins. In humans these cyanotoxins affect various tissues, including the liver, central and peripheral nervous system, kidneys, and reproductive organs among others. They induce acute effects at low doses in the parts-per-billion range and some are tumor promoters linked to chronic diseases such as liver and colorectal cancer. The occurrence of cyanoHABs and cyanotoxins in lakes presents challenges for maintaining safe recreational aquatic environments and the production of potable drinking water. CyanoHABs are a growing problem in the North American (Laurentian) Great Lakes basin. This review summarizes information on the occurrence of cyanoHABs in the Great Lakes, toxicological effects of cyanotoxins, and appropriate numerical limits on cyanotoxins in finished drinking water.

Chamber personnel's use of Nitrox 50 during hyperbaric oxygen treatment: a quality study--research report.

OBJECTIVE: We aimed to evaluate the feasibility and safety of using Nitrox 50 as breathing gas during attendance in a multiplace hyperbaric chamber. METHODS: Paper logs between Jan.-Dec. 2011 were reviewed to analyze nitrogen gas-loading, actual bottom time, total bottom time and surface interval time. With the use of the Norwegian Diving Tables nitrogen gas-loading was converted to Repetitive Group Letters. Symptoms of decompression sickness and health problems related to hyperbaric exposures were registered at weekly staff meetings. The chamber personnel breathed chamber air or Nitrox 50. RESULTS: 1,207 hyperbaric exposures were distributed to five chamber attendants and technicians, 14 doctors, and six nurses. Nitrox 50 was inhaled on 978 occasions (81.0%). Median nitrogen gas-loading after first pressurization complied with Repetitive Group Letter A (range A-E), second to C (range A-F), third to D (range A-F), fourth to E (range C-H), fifth to F (range C-H), and sixth to E (range B-G). No symptoms of decompression sickness were reported (95% CI 0.00-0.33%). CONCLUSION: Breathing Nitrox 50 during repetitive hyperbaric sessions seems to be feasible and safe while meeting high demands in number of treatment sessions and patient flow and with fewer people employed in the hyperbaric unit.

Manipulating vineyard nitrogen on a saline site: 1. Effect of nitrogen on growth, grape yield and nutrients of Vitis vinifera L. cv Shiraz.

BACKGROUND: With increased prevalence of saline irrigation water applied to vines worldwide, the issue of appropriate nitrogen management is of concern. Different rates of nitrogen per vine as urea were applied to Shiraz vines on own roots over four seasons in a low-rainfall, saline growing environment. RESULTS: Application of nitrogen in the vineyard early in the season not only altered the vine nitrogen status but also increased some other elements in the petioles, notably chloride and sodium but also manganese and magnesium. In contrast, nitrogen application decreased petiole phosphorus. In comparison with the majority of nitrogen studies on non-saline sites, nitrogen-induced growth responses were restricted under the saline conditions in this study. While some changes in canopy density in response to nitrogen were observed, this did not affect light interception in the fruit zone. Yield responses were varied and could be related to the nutritional conditions under which bud development and flowering took place. CONCLUSION: This study demonstrated that current best practice guidelines, in terms of rate of nitrogen applied, for correcting a nitrogen deficiency on a non-saline site may not be appropriate for saline sites and that application of nitrogen can increase the potential for salt toxicity in vines.

Eficiência nutricional do Nitrogênio e produção de biomassa em Calendula officinalis L. (Asteraceae) em condições de casa de vegetação / Nitrogen nutritional efficiency and biomass production in Calendula officinalis L. (Asteraceae) under greenhouse conditions

O objetivo deste trabalho foi avaliar o efeito da aplicação de diferentes doses de nitrogênio no solo e de épocas de coleta sobre a eficiência nutricional do nitrogênio e a produção de biomassa em Calendula officinalis L. (Asteraceae) em condições de casa de vegetação. O substrato utilizado foi a camada de 0 - 20 cm de Latossolo Vermelho Distroférrico. O delineamento experimental foi inteiramente casualizado, com quatro repetições. Os tratamentos foram constituídos de quatro doses de N (0, 21, 42 e 84mg dm-3) e cinco épocas de colheita (15, 30, 45, 60 e 90 dias após o transplante). O teor de N na inflorescência de calêndula reduziu com as épocas de coleta, redução essa que ocorreu possivelmente devido à menor eficiência da absorção desse elemento pela planta e menor translocação do N para as inflorescências. Pode se concluir que as épocas de avaliação influenciaram na resposta da planta à eficiência de absorção (EFA), sendo a máxima EFA de N aos 51 dias após o transplante das mudas. Observou-se aumento na translocação de N da parte aérea (folhas e caules) para as inflorescências, tendo como consequência a redução do N na parte aérea. Houve incremento na produção de biomassa de calêndula em função das épocas de coleta , e do aumento das doses de N aplicadas no solo. A eficiência nutricional do N foi influenciada pelas épocas de avaliação e pelo teor de N presente no solo.

The aim of this study was to evaluate the effect of both the application of different nitrogen levels on the soil and the harvest periods on nitrogen nutritional efficiency and biomass production in Calendula officinalis L. (Asteraceae) under greenhouse conditions. The employed substrate was 0-20cm layer of Oxisol. Experimental design was completely randomized, with four replicates. Treatments consisted of four N levels (0, 21, 42 and 84 mg dm-3) and five harvest periods (15, 30, 45, 60 and 90 days after transplanting). N levels in Calendula officinalis inflorescences reduced with the harvest periods, and such a reduction was probably due to the lower efficiency of absorption of this element by the plant and to the lower N translocation to inflorescences. We can conclude that the evaluation periods influenced the response of plants to uptake efficiency (UE), and the maximal UE for N was found at 51 days after transplanting of seedlings. There was an increase in N translocation from the shoot (leaves and stems) to inflorescences, which has as consequence N reduction in the shoot. Calendula officinalis biomass production increased with the harvest periods and with the increase in the N levels applied on the soil. N nutritional efficiency was influenced by both the evaluation periods and the N levels present on the soil.

Nitrox permits direct exit for attendants during extended hyperbaric oxygen treatment.

BACKGROUND: Intermittent breathing of oxygen-enriched air, nitrox (1:1 air:oxygen, 60.5% O2), for attendants in multiplace hyperbaric chambers should enable treatment protocols (HOPAN - hyperbaric oxygen protocol attendants' nitrox) of up to 200 minutes at 2.8 atmospheres absolute (ATA), while retaining the option of a direct decompression and exit. METHODS: HOPAN with cycles of 15 minutes of nitrox breathing followed by 10 minutes of chamber air for attendants were occasionally used from 2007-2009. HOPAN vs. LTP (local treatment protocols) were evaluated via an anonymous enquiry among attendants; patients' medical records were followed six months post-HBO2 treatment (HBO2T). RESULTS: 88 HOPANs, with 59 chamber attendants assisting 30 patients, were documented. HOPAN duration ranged from 55-167 minutes (median 140 minutes). 31/59 attendants answered the enquiry. Perceived comfort of each protocol (HOPAN vs. LTP) by attendants was reported as equal. Symptoms, both minor (parestesias) and severe (joint pain), were reported in connection with LTP, while only one occurrence (mild joint pain) was reported in connection with HOPAN. No complications were documented among the attendants or the patients. It is suggested that nitrox breathing for chamber attendants provide flexible HBO2T for patients at 2.8 ATA for up to 200 minutes within no-decompression limits, facilitating future studies of HBO2T dosage.

Neurological oxygen toxicity.

SCUBA diving has several risks associated with it from breathing air under pressure--nitrogen narcosis, barotrauma and decompression sickness (the bends). Trimix SCUBA diving involves regulating mixtures of nitrogen, oxygen and helium in an attempt to overcome the risks of narcosis and decompression sickness during deep dives, but introduces other potential hazards such as hypoxia and oxygen toxicity convulsions. This study reports on a seizure during the ascent phase, its potential causes and management and discusses the hazards posed to the diver and his rescuer by an emergency ascent to the surface.

Respostas do capim-Tifton 85 à aplicação de nitrogênio: cobertura do solo, índice de área foliar e interceptação da radiação solar / Responses of the grass Tifton 85 to the application of nitrogen: soil cover, leaf area index, and solar radiation interception

Estudaram-se os efeitos da adubação nitrogenada sobre o crescimento do capim Tifton 85 (Cynodon spp. cv. Tifton 85), em termos de ocorrência de plantas e altura do dossel, índice de área foliar e interceptação de radiação fotossinteticamente ativa. O estudo foi desenvolvido sobre um planossolo de ocorrência em campo experimental. Os tratamentos consistiram de níveis de N (0; 150; 300; 450 e 600kg/ha de N-ureia, aplicados em duas vezes), arranjados em um desenho experimental de blocos inteiramente ao acaso, com quatro repetições. As avaliações foram realizadas semanalmente, entre 10 e 40 dias após o corte. Tanto a ocorrência de plantas como a altura do dossel responderam à adubação nitrogenada, conforme um padrão de resposta que variou, sazonalmente, em função das doses de N em interação com as condições ambientais. A expansão da área foliar e a interceptação da radiação fotossinteticamente ativa associada, também foram controladas direta e proporcionalmente pelas doses de N aplicadas, sendo maximizadas a valores de índice de área foliar em torno de 4,0.

The effects of nitrogen (N) fertilization levels on the growth patterns of the grass Tifton 85 (Cynodon spp. cv.Tifton 85) were studied in terms of occurrence of plants, sward height, leaf area index, and photosynthetically active radiation interception (PARint). The field trial was made in an experimental area. Treatments consisted of N levels (0; 150; 300; 450; and 600kg/ha N-urea, split in two applications) arranged in an experimental design of entirely randomized blocks with four repetitions. Plots were weekly sampled, from the day 10th to 40th after cutting. Both occurrence of plants as well as sward height were responsive to nitrogen fertilization according to a response pattern that seasonally varied, depending on N rates and environmental conditions; thus, demonstrating their sensitivity as indicators of growth conditions and canopy structure. Leaf expansion and its associated PAR interception were also directly and proportionately controlled by N rates, being maximized to values of leaf area index around 4.0.

Guiding principles in choosing a therapeutic table for DCI hyperbaric therapy.

Hyperbaric therapy is the basis of treatment for pervasive development disorders. For this reason, the choice of the right therapeutic table for each case is critical. Above all, the delay in recompression time with respect to the first symptoms and to the severity of the case must be considered. In our experience, the use of low-pressure oxygen tables resolves almost all cases if recompression takes place within a short time. When recompression is possible almost immediately, the mechanical effect of reduction on bubble volume due to pressure is of remarkable importance. In these cases, high-pressure tables can be considered. These tables can also be used in severe spinal-cord decompression sickness. The preferred breathing mixture is still disputed. Heliox seems to be favored because it causes fewer problems during the recompression of divers, and above all, because nitrox can cause narcosis and contributes nitrogen. Saturation treatment should be avoided or at least used only in special cases. In cases of arterial gas embolism cerebral injury, it is recommended to start with an initial 6 ATA recompression only if the time between symptom onset and the beginning of recompression is less than a few hours.

The contribution of marsh zones to water quality in Dutch shallow lakes: a modeling study.

Many lakes have experienced a transition from a clear into a turbid state without macrophyte growth due to eutrophication. There are several measures by which nitrogen (N) and phosphorus (P) concentrations in the surface water can be reduced. We used the shallow lake model PCLake to evaluate the effects of three measures (reducing external nutrient loading, increasing relative marsh area, and increasing exchange rate between open water and marsh) on water quality improvement. Furthermore, the contribution of different retention processes was calculated. Settling and burial contributed more to nutrient retention than denitrification. The model runs for a typical shallow lake in The Netherlands showed that after increasing relative marsh area to 50%, total phosphorous (TP) concentration in the surface water was lower than the Maximum Admissible Risk (MAR, a Dutch government water quality standard) level, in contrast to total nitrogen (TN) concentration. The MAR levels could also be achieved by reducing N and P load. However, reduction of nutrient concentrations to MAR levels did not result in a clear lake state with submerged vegetation. Only a combination of a more drastic reduction of the present nutrient loading, in combination with a relatively large marsh cover (approximately 50%) would lead to such a clear state. We therefore concluded that littoral marsh areas can make a small but significant contribution to lake recovery.

Effects of nitrogen and helium on CNS oxygen toxicity in the rat.

The contribution of inert gases to the risk of central nervous system (CNS) oxygen toxicity is a matter of controversy. Therefore, diving regulations apply strict rules regarding permissible oxygen pressures (Po(2)). We studied the effects of nitrogen and helium (0, 15, 25, 40, 50, and 60%) and different levels of Po(2) (507, 557, 608, and 658 kPa) on the latency to the first electrical discharge (FED) in the EEG in rats, with repeated measurements in each animal. Latency as a function of the nitrogen pressure was not homogeneous for each rat. The prolongation of latency observed in some rats at certain nitrogen pressures, mostly in the range 100 to 500 kPa, was superimposed on the general trend for a reduction in latency as nitrogen pressure increased. This pattern was an individual trait. In contrast with nitrogen, no prolongation of latency to CNS oxygen toxicity was observed with helium, where an increase in helium pressure caused a reduction in latency. This bimodal response and the variation in the response between rats, together with a possible effect of ambient temperature on metabolic rate, may explain the conflicting findings reported in the literature. The difference between the two inert gases may be related to the difference in the narcotic effect of nitrogen. Proof through further research of a correlation between individual sensitivity to nitrogen narcosis and protection by N(2) against CNS oxygen toxicity in rat may lead to a personal O(2) limit in mixed-gas diving based on the diver sensitivity to N(2) narcosis.

Consequences of livestock grazing on water quality and Benthic algal biomass in a Canadian natural grassland plateau.

The effects of livestock grazing on selected riparian and stream attributes, water chemistry, and algal biomass were investigated over a two-year period using livestock enclosures and by completing stream surveys in the Cypress Hills grassland plateau, Alberta, Canada. Livestock enclosure experiments, partially replicated in three streams, comprised four treatments: (1) early season livestock grazing (June-August), (2) late season livestock grazing (August-September), (3) all season grazing (June-September), and (4) livestock absent controls. Livestock grazing significantly decreased streambank stability, biomass of riparian vegetation, and the extent to which aquatic vegetation covered the stream channels compared with livestock-absent controls. Water quality comparisons indicated significant differences among the four livestock grazing treatments in Battle and Graburn creeks but not in Nine Mile Creek. In Graburn Creek, the concentration of total phosphorus in the all-season livestock grazing treatment was significantly higher than that in the livestock-absent control, and the early season and late season grazing treatments. Concentrations of soluble reactive phosphorus in the all-season livestock grazing treatment also exceeded that in livestock-absent control. In contrast, differences in water quality variables in the remaining 22 comparisons (i.e., 22 of the total 24 comparisons) were minor even when differences were statistically significant. Effects of livestock grazing on algal biomass were variable, and there was no consistent pattern among creeks. At the watershed scale, spatial variation in algal biomass was related (P < 0.05) with concentrations of NO(2)(-) + NO(3) (-) and soluble reactive phosphorus in two of the four study creeks. Nutrient diffusing substrata experiments showed that algal communities were either nitrogen-limited or not limited by nutrients, depending on stream and season.