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PubMed2000

Mitigating epidemics caused by non-persistently transmitted aphid-borne viruses: the role of the pliant environment.

Using Soybean mosaic virus as a model system, the rate, magnitude and timing of epidemics caused by non-persistently transmitted, aphid-borne viruses are examined under various field conditions. Emphasis is placed on the behavioural responses of vectors to environmental cues, although all three biotic components (host plant, vector and virus) are considered. Both single and double manipulations of the cropping system environment are explored using a computer model developed earlier by Ruesink and Irwin (Plant Virus Epidemics: Monitoring, Modelling and Predicting Outbreaks.

Animals↗
PubMed2003

Some histologic and biochemical evidence for mitigation of cyanide-induced tissue lesions by antioxidant vitamin administration in rabbits.

The effect of antioxidant vitamins on cyanide-induced tissue damage was investigated in New Zealand White rabbits using a combination of colorimetric, spectrophotometric, enzymatic, gravimetric and histological methods. Three groups of rabbits (six per group) were used in a 4-week feeding experiment. One group received pure grower's mash, while a second group was fed mash containing 400 ppm inorganic cyanide. The third group received daily oral doses of vitamins A, C and E, in addition to mash and 400 ppm cyanide. There were significant decreases (P < 0.05) in activities of superoxide dismutase (SOD), catalase and alkaline phosphatase (AP) in the liver, lung and kidney of the two groups given cyanide, but the decreases were significantly lower (P < 0.05) in the group fed antioxidant vitamins. In addition, the antioxidant vitamin supplementation led to marked reductions in the severity of histopathological degeneration in these tissues. These results strongly suggest that cyanide-induced tissue lesions may be relieved by adequate intake of antioxidant vitamin supplements.

Animals↗
PubMed1997

Testosterone pretreatment mitigates cadmium toxicity in male C57 mice but not in C3H mice.

Previous work has indicated that testosterone pretreatment protects against cadmium-induced toxicity in male rats while other data indicate that pretreatment of mice with testosterone offers no such protection against cadmium. Since cadmium toxicity may vary widely with species and strain, we examined the effect of testosterone pretreatment on cadmium toxicity in two strains of mice, one that is sensitive (C3H) and one that is resistant (C57) to cadmium toxicity. A single sc injection of 20 micromol CdCl2/kg to C3H mice or 45 micromol CdCl2/kg to C57 mice proved very toxic, causing 50%, and 44% mortalities, respectively. However, when C57 mice were pretreated with testosterone (5 mg/kg, s.c., at - 48, - 24, and 0 h) prior to cadmium (45 micromol/kg), complete resistance to cadmium-induced lethality developed. Testosterone had no effect on cadmium-induced lethality in C3H mice. Testosterone prevented extensive hepatocellular damage caused by cadmium in C57 mice and also significantly reduced cadmium-induced elevations in serum lactate dehydrogenase (LDH) activity and blood urea nitrogen (BUN), which are indicators of hepatic and renal function, respectively. The toxicokinetics of cadmium were apparently not affected by testosterone pretreatment, as the distribution of cadmium to liver in either strain was unchanged by the steroid. Cadmium-induced metallothionein (MT) levels in liver and kidney of C57 mice were increased in testosterone-pretreated mice given the higher doses of metal but no such enhancement of MT synthesis occurred in C3H mice. This increase in MT may provide some level of protection against cadmium toxicity in the C57 mice. These results indicate that testosterone pretreatment prevents toxicity of cadmium in male C57 mice, possibly through enhancement of MT synthesis, but has no effect in male C3H mice.

Animals↗
PubMed1998

Mitigation of the somnolence of insulin-induced hypoglycemia by a vasopressin V1 receptor antagonist in the rhesus monkey.

Insulin-induced hypoglycemia causes somnolence in rhesus monkeys, a phenomenon usually considered an aspecific consequence of neuroglycopenia. Previous observations from our laboratory have raised the possibility that arginine vasopressin (AVP) may also play a role in this decrease in wakefulness. In the present study we tested this hypothesis by inducing hypoglycemia (approximately 40 mg/dl) in ovariectomized rhesus monkeys by intravenous administration of insulin in the presence of continuous intracerebroventricular infusions of the V1 receptor antagonist [deamino-Pen1, O-Me-Tyr2,Arg8]-vasopressin (180 micrograms/60 microliters per h) or of its vehicle alone (artificial cerebrospinal fluid, 60 microliters/h). Wakefulness was assessed by a scoring system by observers blinded to the experimental protocol. The AVP antagonist significantly attenuated the decrease in wakefulness observed in response to insulin-induced hypoglycemia (p < .03) without increasing blood glucose levels. These and previous findings suggest that the somnolence induced by a moderate degree of hypoglycemia may not entirely be the direct consequence of neuroglycopenia and that AVP may, directly or indirectly, be involved.

Animals↗
PubMed1988

Science and technology in mitigating AIDS.

The workshop emphasized contributions of genetic engineering in providing reagents and techniques for diagnosing and monitoring HIV infections. Despite a variety of tests for specific antibodies, virus antigens and nucleic acids no consistent serum profile has emerged that correlates well with virus life cycle or clinical course. HIV infections are a great deal more complex than hepatitis B infections where diagnosis and prognosis are very accurately based on serologic profiles. HIV generates at least 15 virus proteins all of which are immunogenic. The workshop emphasized studies on immunogenicity of the proteins. Full understanding of the virus life cycle and the clinical course of disease may require in-depth studies of the production and immunogenicity of the virus-directed catalytic and regulatory gene products. Fortunately, all of these reagents can be produced through biotechnology. The new techniques described in the workshop will allow expanded studies to proceed rapidly.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Red wine mitigates the postprandial increase of LDL susceptibility to oxidation.

The aim of the present study was to verify the extent of oxidative stress induced by a meal at plasma and LDL level, and to investigate the capacity of red wine to counteract this action. In two different sessions, six healthy men ate the same test meal consisting of "Milanese" meat and fried potatoes. The meal was taken either with 400 ml red wine or with an isocaloric hydroalcoholic solution. Oxidative stress at plasma level was estimated through the measure of ascorbic acid, alpha-tocopherol, protein SH groups, uric acid, and antioxidant capacity, measured before and 1 and 3 h after the meal. The change in the resistance of LDL to oxidative modification was taken as an index of exposure to pro-oxidants. The susceptibility to Cu(II)-catalyzed oxidation of baseline and postprandial LDL was measured as conjugated dienes formation, tryptophan residues, and relative electrophoretic mobility. The experimental meal taken with wine provoked a significant increase in the total plasma antioxidant capacity and in the plasma concentration of alpha-tocopherol and SH groups. Postprandial LDL was more susceptible to metal-catalyzed oxidation than the homologous baseline LDL after the ethanol meal. On the contrary, postprandial LDL obtained after the wine meal was as resistant or more resistant to lipid peroxidation than fasting LDL.

Adult↗
PubMed2002

Aggregation of eumelanin mitigates photogeneration of reactive oxygen species.

Melanins protect tissue by absorption and rapid nonradiative, nonreactive dissipation of ultraviolet (UV) light. However, melanins also produce reactive oxygen species (ROS) upon UV illumination. A chemical understanding of this dichotomy of photoprotection and phototoxicity has not been established. Herein this issue is examined by studying the UV-B induced oxidation and reduction of cytochrome c by ROS generated by different aggregation states of eumelanin. The quantum yield for superoxide anion by unaggregated oligomers is 7.4 x 10(-3), an order of magnitude greater than that characteristic of the bulk pigment. The quantum efficiency of hydrogen peroxide production by oligomers is 5.7 x 10(-3), and its production is attributed to reaction between superoxide anion and hydroquinone groups on eumelanin oligomers. Aggregation of oligomers results in a reduction of these quantum yields, having a significantly greater effect on the efficiency of hydrogen peroxide production. This effect is attributed to the decrease in surface concentration of hydroquinone sites upon aggregation. The effect of aggregation on the photogeneration of ROS serves to provide a foundation for the understanding of the dichotomy of photoprotective and phototoxic properties of melanin.

Animals↗
PubMed2003

Vitamin E supplementation in the mitigation of carbon tetrachloride induced oxidative stress in rats.

Oxidative stress is implicated in the pathophysiology of a number of chronic diseases including atherosclerosis, diabetes, cataracts and accelerated aging. The aim of this study was to elucidate the protective role of vitamin E supplementation when oxidative stress is induced by CCl4 administration, using the rat as a model. Rats were fed diets for four weeks either with or without dl-alpha-tocopherol acetate supplementation. Half of the rats (n = 9) from each of the diet groups were then challenged with CCl4 at the completion of the four week diet period. Plasma levels of 8-iso-PGF(2alpha), antioxidant micronutrients and antioxidant enzyme activities were measured to examine changes in oxidative stress subsequent to the supplementation of dl-alpha-tocopherol in the diet. Plasma alpha-tocopherol (vitamin E) concentrations were higher for the groups supplemented with dl-alpha-tocopherol acetate, however the supplemented diet group that was subsequently challenged with CCl4 had significantly lower (p <0.001) plasma alpha-tocopherol concentration than the dl-alpha-tocopherol acetate diet group that was not challenged with CCl4. Total plasma 8-iso-PGF(2alpha) concentration was elevated in diet groups challenged with CCl4, however, the concentration was significantly lower (p <0.001) when the diet was supplemented with dl-alpha-tocopherol acetate. The antioxidant enzymes were not influenced by either dietary alpha-tocopherol manipulation or by the inducement of oxidative stress with CCl4. Plasma concentrations of trans-retinol (vitamin A) were reduced by CCl4 administration in both the dl-alpha-tocopherol acetate supplemented and unsupplemented diet groups. The results of this study indicate that dl-alpha-tocopherol acetate supplementation was protective of lipid peroxidation when oxidative stress is induced by a pro-oxidant challenge such as CCl4.

Animals↗
PubMed2003

Decursin from Angelica gigas mitigates amnesia induced by scopolamine in mice.

We previously reported that a total methanolic extract of the underground part of Angelica gigas Nakai (Umbelliferae) (here-in-after abbreviated AG) significantly inhibited acetylcholinesterase (AChE) activity. We characterized 12 coumarin derivatives including both decursin and decursinol from extracts of AG. In this study, we evaluated the anti-amnestic activity of decursin, a major coumarin constituent isolated from AG, in vivo using ICR mice with amnesia induced by scopolamine (1 mg/kg body weight, s.c.). Decursin, when administered to mice at 1 and 5 mg/kg body weight i.p., significantly ameliorated scopolamine-induced amnesia as measured in both the passive avoidance test and the Morris water maze test. Moreover, decursin significantly inhibited AChE activity by 34% in the hippocampus of treated mice. These results indicate that decursin may exert anti-amnestic activity in vivo through inhibition of AChE activity in the hippocampus.

Acetylcholinesterase↗
PubMed1996

Enhancing contaminant control to mitigate aeroallergies.

BACKGROUND: Modern construction techniques such as sealing buildings and reducing air exchange rates to conserve energy often increase indoor air contaminant concentrations, a problem for people with asthma and aeroallergies. Further, a large proportion of the contaminants that are found in indoor air do not reach the filters because the motion of particulates less than about 3 microns in size, 99% of all particulates, is determined more by the normal electrical forces in a room than by the air currents. OBJECTIVE: To determine whether the natural process of aerosol coagulation, which increases particle size, can be speeded-up, thereby enhancing the effectiveness of air currents in returning contaminants to the filters and improving contamination control. METHOD: A set of four experiments using various methods involving particulate and gaseous contaminants are presented. RESULTS: Statistically significant differences in room contaminant load were found in the various experiments as a function of the treatment used. CONCLUSIONS: The effectiveness of filters can be significantly enhanced and the concentration of contaminants in indoor air can be significantly reduced in a straight-forward direct way. The physics underlying the phenomena is described. The implications for allergy and asthma patients are significant, for we now have a new means to substantially improve indoor air quality.

Aerosols↗
PubMed2002

c-Myc can induce DNA damage, increase reactive oxygen species, and mitigate p53 function: a mechanism for oncogene-induced genetic instability.

Oncogene overexpression activates p53 by a mechanism posited to involve uncharacterized hyperproliferative signals. We determined whether such signals produce metabolic perturbations that generate DNA damage, a known p53 inducer. Biochemical, cytological, cell cycle, and global gene expression analyses revealed that brief c-Myc activation can induce DNA damage prior to S phase in normal human fibroblasts. Damage correlated with induction of reactive oxygen species (ROS) without induction of apoptosis. Deregulated c-Myc partially disabled the p53-mediated DNA damage response, enabling cells with damaged genomes to enter the cycle, resulting in poor clonogenic survival. An antioxidant reduced ROS, decreased DNA damage and p53 activation, and improved survival. We propose that oncogene activation can induce DNA damage and override damage controls, thereby accelerating tumor progression via genetic instability.

Cells, Cultured↗
PubMed2004

The link between marital conflict and child adjustment: parent-child conflict and perceived attachments as mediators, potentiators, and mitigators of risk.

Parent-child conflict and perceived attachments to parents were examined as predictors, mediators, and moderators in the marital conflict-child adjustment connection in a sample of older children and young adolescents. After controlling for marital conflict, parent-child conflict predicted additional unique variance mainly for children's externalizing problems, and attachments to parents accounted for unique variance in children's externalizing and internalizing problems. Moderation effects illustrated that a higher level of parent-child conflict was a vulnerability factor, whereas a secure attachment was a protective factor, for behavior problems associated with marital conflict. Mediation effects were also evident and supported the proposition that parent-child conflict and attachment to parents mostly are partial mediators of effects in the marital conflict-child outcomes link. The findings illustrate the aggregation, potentiation, and amelioration of risk for adjustment problems associated with marital conflict, and highlight the importance of assessing multiple systems within the family.

Child↗
PubMed2000

Mitigation of Rayleigh and Raman spectral interferences in multiway calibration of excitation-emission matrix fluorescence spectra.

A weighted parallel factor analysis (W-PARAFAC) model is applied to excitation-emission matrix (EEM) fluorescence spectra of carbamate pesticides to aid with calibration in the presence of Raman scattering. Traditional PARAFAC inefficiently models the Raman scattering, resulting in prediction and calibration errors when a significant background is present. Four different weighting strategies were investigated and compared with subtraction of the appropriate sample background. Using a binary weighting strategy produced superior results, compared with a continuous distribution of weights. Further choice of weighting strategies, which are optimized to include either maximum analyte signal or to exclude a maximum amount of background scattering, is dependent on the degree of overlap and relative signal intensity.

Calibration↗
PubMed2005

Biofiltration for mitigation of methane emission from animal husbandry.

Removal of methane from exhaust air of animal houses and manure storage has a large potential for the reduction of greenhouse gas emissions from animal husbandry. The aim of this study was to design a biofilter for methane removal at a full-scale livestock production facility. Air from the headspace of a covered 6 m3 liquid manure storage (air flow: 0.75-8.5 m3 m(-3) h(-1); CH4: 500-5500 mg m(-3)) was treated in an experimental biofilter (160 L). The filterbed, a mixture of compost and perlite in a 40:60 (v/v) ratio, was inoculated with activated sludge that had shown a good methane oxidation rate as compared to pure cultures in preceding laboratory tests. Methane removal up to 85% could be achieved in the experimental biofilter. The methane removal (g m(-3) h(-1)) appeared to be proportional to the concentration (g m(-3)) with k = 2.5 h(-1). Relatively low methane concentrations and high air flows, as reported for the exhaust air of animal houses, would require very large biofilter sizes. Extrapolation of the results showed that treatment of air from a 1000 m3 liquid manure storage with a methane concentration of 22 g m(-3) would require a 20 m3 biofilter for a desired emission reduction of 50%. The costs for such a biofilter are USD 26 per t of CO2 equiv reduction.

Animal Husbandry↗
PubMed2004

Evaluation of a biologically active cover for mitigation of landfill gas emissions.

Landfills are the third largest source of anthropogenic CH4 in the United States, and there is potential for reduction in this source of greenhouse gases and other contaminants. The objective of this work was to contrast emissions of CH4 and non-methane organic compounds (NMOCs) from landfill cells covered with soil or a biologically active cover consisting of yard waste compost. On the basis of four field campaigns over 14 months, CH4 emissions from the biocover (BC) varied from -1.73 to 1.33 g m(-2) d(-1), with atmospheric uptake measured in 52% of tests. BC emissions did not increase when the gas collection system was turned off. Uptake of atmospheric CH4 was measured in 54% of tests on the soil cover (SC) when the gas collection was system active and 12% when the gas collection system was off. Many (26%) relatively high fluxes (>15 g m(-2) d(-1)) were measured from the SC as were some dramatic effects due to deactivation of the gas collection system. In tests with positive emissions, stable isotope measurements showed that the BC and SC were responsible for oxidation of 55% and 21% of the CH4 reaching the bottom of the respective cover. Seven of the highest 10 NMOC emissions were measured in the SC, and 17 of 21 fluxes for speciated organic compounds were higher in the SC. The relationship between CH4, NMOC, and individual organic compound emissions suggested a correlation between CH4 and trace organic oxidation. BCs can reduce landfill gas emissions in the absence of a gas collection system and can serve as a polishing step in the presence of an active system.

Air Pollutants↗
PubMed2006

Mitigation of ammonia and hydrogen sulfide emissions by stable aqueous foam-microbial media.

Stable aqueous foam-microbial media consisting of protein-based foams and odor-degrading bacteria were developed to control the emissions of odorous compounds. The optimum foam formulation was determined based on foam characteristics including 50% drainage time, foam lifetime, and foam expansion ratio. When only the aqueous foam was applied onto the surface of a test odor source (i.e., swine manure), ammonia emission was completely suppressed for about 177, 225, 265, 297, and 471 min when the height of foam barrier was 2.5, 5, 10, 15, and 30 cm, respectively. According to the increasing foam height, ammonia emission rates after breakthrough points decreased to 0.16, 0.13, 0.09, 0.07, and 0.02 mg/m3/min, and thus volatilized ammonia concentrations decreased significantly after 600 min. Hydrogen sulfide was similarly suppressed. Ammonia emission was better controlled by incorporating odor-degrading bacteria into the aqueous foam. The odor suppression capacity of the 5-cm foam barrier with microbes was more than eight times greater than that of the barrier only and was similar to that of 30-cm foam barrier without microbes after 1440 min. A significant amount of dinitrogen gas was evolved by the foam-microbial media, indicating a successful biological transformation of ammonia.

Air Pollutants↗