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41.
Ivie MA Pollock DA Gustafson DL Ivie LL Rasolomandimby J Swearingen WD 《Journal of economic entomology》2002,95(4):651-660
A community of 225 species of Coleoptera was used as a surrogate to evaluate nontarget effects of entomopathogenic fungi under development as biopesticides for use against the Malagasy migratory locust Locusta migratoria capito Saussure (Orthoptera: Acrididae). Evaluation of a standard chemical treatment of fenitrothion + esfenvalerate, two indigenous isolates of Metarhiziumflavoviride Gams & Roszsypol (SP3 and SP9), and an indigenous isolate of Beauveria bassiana (Balsamo) Vuillemin (SP16) against an untreated control in a replicated field trial in southern Madagascar showed that one of the isolates of M. flavoviride (SP3) and fenitrothion + esfenvalerate had distinct effects on nontarget beetle communities that were similar to each other. The other two isolates had no detectable effects compared with the untreated control. Based on an evaluation of the species affected, the similar effects of SP3 and the chemical pesticide are hypothesized to be the result of a perturbation of predator-prey relationships, with a distinct tendency to be manifested via predators. The data indicate that use of SP9 and SP16 would have minimal detrimental effects on the biodiversity of nontarget beetles, but that SP3 needs further testing. 相似文献
42.
Campbell SJ Sabeti P Fielding K Sillah J Bah B Gustafson P Manneh K Lisse I Sirugo G Bellamy R Bennett S Aaby P McAdam KP Bah-Sow O Lienhardt C Hill AV 《Immunogenetics》2003,55(7):502-507
Evidence for linkage between tuberculosis and human chromosomal region Xq26 has previously been described. The costimulatory molecule CD40 ligand, encoded by TNFSF5 and located at Xq26.3, is a promising positional candidate. Interactions between CD40 ligand and CD40 are involved in the development of humoral- and cell-mediated immunity, as well as the activation of macrophages, which are the primary host and effector cells for Mycobacterium tuberculosis. We hypothesised that common variation within TNFSF5 might affect susceptibility to tuberculosis disease and, thus, might be responsible for the observed linkage to Xq26. Sequencing 32 chromosomes from a Gambian population identified nine common polymorphisms within the coding, 3 and 5 regulatory sequences of the gene. Six single nucleotide polymorphisms (SNPs) and a 3 microsatellite were genotyped in 121 tuberculosis patients and their available parents. No association with tuberculosis was detected for these variants using a transmission disequilibrium test, although one SNP at –726 showed some evidence of association in males. This finding, however, did not replicate in a separate case control study of over 1,200 West African individuals. We conclude that common genetic variation in TNFSF5 is not likely to affect tuberculosis susceptibility in West Africa and the linkage observed in this region is not due to variation in TNFSF5.Sadly, Professor Steve Bennett passed away in March 2003 相似文献
43.
Human herpesvirus 8 open reading frame 21 is a thymidine and thymidylate kinase of narrow substrate specificity that efficiently phosphorylates zidovudine but not ganciclovir 下载免费PDF全文
Human herpesvirus 8 (HHV8) open reading frame (ORF) 21 is predicted to encode a protein similar to the thymidine kinase (TK) enzyme of other herpesviruses. Expressed in mammalian cells, ORF 21 was found to have low TK activity, based on poor growth in media containing hypoxanthine-aminopterin-thymidine (HAT) and low incorporation of [(3)H]thymidine into high-molecular-weight DNA. Kinetic analysis using HHV8 TK as a purified glutathione S-transferase (GST) fusion protein showed that the enzyme has a comparatively high K(m) for thymidine (dThd) of approximately 33.2 microM. Nearly 50% of the phosphorylated product of the reaction with dThd was thymidylate. This monophosphate kinase activity was more pronounced with 3'-azido-3'-deoxythymidine (AZT), in which 78% of the reaction product was AZT diphosphate. Thymidine analogs competitively inhibited dThd phosphorylation by HHV8 TK, while 2'-deoxyguanosine, 2'-deoxyadenosine, 2'-deoxycytidine, and corresponding analogs did not. Further competition experiments revealed that the nucleoside analog ganciclovir (GCV), at up to 1,000-fold molar excess, could not significantly inhibit dThd phosphorylation by the enzyme. In support of these data, 143B TK(-) cells expressing HHV8 TK phosphorylated GCV very poorly and were not susceptible to GCV toxicity compared to parental cells. Phosphorylation of [(3)H]GCV by a purified GST-HHV8 TK fusion protein was not detected by high-pressure liquid chromatography analysis. Structural features of HHV8 TK substrate recognition were investigated. Therapeutic implications of these findings are discussed. 相似文献
44.
Clustering Timber Harvests and the Effect of Dynamic Forest Management Policy on Forest Fragmentation 总被引:1,自引:1,他引:0
Eric J. Gustafson 《Ecosystems》1998,1(5):484-492
To integrate multiple uses (mature forest and commodity production) better on forested lands, timber management strategies
that cluster harvests have been proposed. One such approach clusters harvest activity in space and time, and rotates timber
production zones across the landscape with a long temporal period (dynamic zoning). Dynamic zoning has been shown to increase timber production and reduce forest fragmentation by segregating uses in time without reducing the spatial extent of timber production. It is reasonable
to wonder what the effect of periodic interruptions in the implementation of such as strategy might be, as would be expected
in a dynamic political environment. To answer these questions, I used a timber harvest simulation model (HARVEST) to simulate
a dynamic zoning harvest strategy that was periodically interrupted by changes in the spatial dispersion of harvests, by changes
in timber production levels, or both. The temporal scale (period) of these interruptions had impacts related to the rate at
which the forest achieved canopy closure after harvest. Spatial dynamics in harvest policies had a greater effect on the amount
of forest interior and edge than did dynamics in harvest intensity. The periodically clustered scenarios always produced greater amounts of forest interior and less forest edge than did their never clustered counterparts. The results suggest that clustering of harvests produces less forest fragmentation than dispersed cutting alternatives,
even in the face of a dynamic policy future. Although periodic episodes of dispersed cutting increased fragmentation, average
and maximum fragmentation measures were less than if clustered harvest strategies were never implemented. Clustering may also
be useful to mitigate the fragmentation effects of socially mandated increases in timber harvest levels. Implementation of
spatial clustering during periods of high timber harvest rates reduced the variation in forest interior and edge through time,
providing a more stable supply of forest interior habitat across the landscape.
Received 19 September 1997; accepted 6 August 1998. 相似文献
45.
A new principle is described for imaging intracellular free calcium [Ca2+]i changes in single, living cells utilizing the fluorescent probe Fura-2. It is based upon video color mixing in real time and allows high-speed visualization, at maximum image resolution, of [Ca2+]i changes without digital image ratioing. The epifluorescence images produced by 340 and 380 nm excitations are stored in two memory buffers of a personal computer-based image processing system. Two video signals are generated independently from each buffer and connected to the red and green inputs of a video display. An image is this way created, in which [Ca2+]i shows up as a specific hue, whereas changes in dye concentration, light intensity, cell thickness show up as variations in brightness of the imaged cells. The method has advantages over conventional ratio imaging, notably simplicity and speed, since no calculations are made. Yet it can be combined with traditional digital image processing. The imaging technique allows monitoring of [Ca2+]i changes in rapidly moving cells, like neutrophils. It is demonstrated that during random locomotion on serum-coated glass surfaces, [Ca2+]i levels appeared to oscillate and that the frequency of the oscillations are related to locomotive activity. Furthermore, in Ca2+ free medium, the cells continue to move and phagocytose in the presence of Ca2+ ionophore (ionomycin) and 2 mM EGTA. In the presence of 1 mM extracellular Ca2+, ionomycin-treated cells were not able to move or phagocytose. 相似文献
46.
47.
Robert Gramling Kathi L Heffner William MP Klein Laura E Zajac Mary Roberts Charles B Eaton 《BioPsychoSocial medicine》2010,4(1):11
Background
More optimistic perceptions of cardiovascular disease risk are associated with substantively lower rates of cardiovascular death among men. It remains unknown whether this association represents causality (i.e. perception leads to actions/conditions that influence cardiovascular disease occurrence) or residual confounding by unmeasured factors that associate with risk perceptions and with physiological processes that promote cardiovascular disease (i.e. inflammation or endothelial dysfunction). 相似文献48.
Jennifer MP Woo Zhuofeng Lin Mohamad Navab Casey Van Dyck Yvette Trejo-Lopez Krystal MT Woo Hongyun Li Lawrence W Castellani Xuping Wang Noriko Iikuni Ornella J Rullo Hui Wu Antonio La Cava Alan M Fogelman Aldons J Lusis Betty P Tsao 《Arthritis research & therapy》2010,12(3):R93
Introduction
The purpose of this study was to evaluate the effects of L-4F, an apolipoprotein A-1 mimetic peptide, alone or with pravastatin, in apoE-/-Fas-/-C57BL/6 mice that spontaneously develop immunoglobulin G (IgG) autoantibodies, glomerulonephritis, osteopenia, and atherosclerotic lesions on a normal chow diet.Methods
Female mice, starting at eight to nine weeks of age, were treated for 27 weeks with 1) pravastatin, 2) L-4F, 3) L-4F plus pravastatin, or 4) vehicle control, followed by disease phenotype assessment.Results
In preliminary studies, dysfunctional, proinflammatory high-density lipoproteins (piHDL) were decreased six hours after a single L-4F, but not scrambled L-4F, injection in eight- to nine-week old mice. After 35 weeks, L-4F-treated mice, in the absence/presence of pravastatin, had significantly smaller lymph nodes and glomerular tufts (PL, LP < 0.05), lower serum levels of IgG antibodies to double stranded DNA (dsDNA) (PL < 0.05) and oxidized phospholipids (oxPLs) (PL, LP < 0.005), and elevated total and vertebral bone mineral density (PL, LP < 0.01) compared to vehicle controls. Although all treatment groups presented larger aortic root lesions compared to vehicle controls, enlarged atheromas in combination treatment mice had significantly less infiltrated CD68+ macrophages (PLP < 0.01), significantly increased mean α-actin stained area (PLP < 0.05), and significantly lower levels of circulating markers for atherosclerosis progression, CCL19 (PL, LP < 0.0005) and VCAM-1 (PL < 0.0002).Conclusions
L-4F treatment, alone or with pravastatin, significantly reduced IgG anti-dsDNA and IgG anti-oxPLs, proteinuria, glomerulonephritis, and osteopenia in a murine lupus model of accelerated atherosclerosis. Despite enlarged aortic lesions, increased smooth muscle content, decreased macrophage infiltration, and decreased pro-atherogenic chemokines in L-4F plus pravastatin treated mice suggest protective mechanisms not only on lupus-like disease, but also on potential plaque remodeling in a murine model of systemic lupus erythematosus (SLE) and accelerated atherosclerosis. 相似文献49.
Van B. Lu S. Balasubramanyan J. E. Biggs M. J. Stebbing S. L. Gustafson K. Todd A. Lai D. Dawbarn W. F. Colmers K. Ballanyi P. A. Smith 《Neurophysiology》2007,39(4-5):272-283
Chronic constriction injury (CCI) of the rat sciatic nerve increases the dorsal horn excitability. This “central sensitization”
leads to behavioral manifestations analogous to those related to human neuropathic pain. We found, using whole-cell recording
from acutely isolated spinal cord slices, that 7-to 10-day-long CCI increases excitatory synaptic drive to putative excitatory
“delay”-firing neurons in the substantia gelatinosa but attenuates that to putative inhibitory “tonic”-firing neurons. A defined-medium organotypic culture (DMOTC) system was
used to investigate the long-term actions of brain-derived neurotrophic factor (BDNF) as a possible instigator of these changes.
When all five neuronal types found in the substantia gelatinosa were considered, BDNF and CCI produced similar patterns, or “footprints,” of changes across the whole population. This pattern
was not seen with another putative “pain mediator,” interleukin 1β. Thus, BDNF decreased synaptic drive to “tonic” neurons
and increased synaptic drive to “delay” neurons. Actions of BDNF on “delay” neurons were presynaptic and involved increased
mEPSC frequency and amplitude without changes in the function of postsynaptic AMPA receptors. By contrast, BDNF exerted both
pre-and post-synaptic actions on “ tonic” cells to reduce the mEPSC frequency and amplitude. These differential actions of
BDNF on excitatory and inhibitory neurons contributed to a global increase in the dorsal horn network excitability as assessed
by the amplitude of depolarization-induced increases in the intracellular [Ca2+]. Experiments with the BDNF-binding protein TrkB-d5 provided additional evidence for BDNF as a harbinger of neuropathic pain.
Thus, the cellular processes altered by BDNF likely contribute to “central sensitization” and hence to the onset of neuropathic
pain.
Neirofiziologiya/Neurophysiology, Vol. 39, Nos. 4/5, pp. 315–326, July–October, 2007. 相似文献
50.
Stable isotopes can be used to elucidate ecological relationships in community and trophic studies. Findings are calibrated
against baselines, e.g. from a producer or primary consumer, assumed to act as a reference to the isotopic context created
by spatio-temporal attributes such as geography, climate, nutrient, and energy sources. The ability of an organism to accurately
represent a community base depends on how, and over what time-scale, it assimilates ambient materials. Freshwater mussels
have served as references for trophic studies of freshwater communities and as indicators of change in nutrient pollution
load or source. Their suitability as reference animals has not yet been fully explored, however. We conducted a series of
studies examining the suitability of freshwater mussels as isotopic baselines, using their ability to reflect variation in
ambient nutrient loads as a case scenario. (1) We analyzed bivalve foot tissue δ15N and δ13C from 22 stream reaches in the Piedmont region of North Carolina, USA to show that compositions varied substantially among
locations. Site mean bivalve δ13C values correlated with site ambient particulate organic matter (POM) δ13C values, and site mean bivalve δ15N values correlated with site ambient water dissolved δ15N-NO3 values. (2) Similarity of results among sample types demonstrated that the minimally invasive hemolymph sample is a suitable
substitute for foot tissue in δ15N analyses, and that small sample sizes generate means representative of a larger population. Both findings can help minimize
the impact of sampling on imperiled freshwater mussel populations. (3) In a bivalve transplantation study we showed that hemolymph
δ15N compositions responded to a shift in ambient dissolved δ15N-NO3, although slowly. The tissue turnover time for bivalve hemolymph was 113 days. We conclude that bivalves serve best as biomonitors
of chronic, rather than acute, fluctuations in stream nutrient loads, and provide initial evidence of their suitability as
time-integrated isotopic baselines for community studies. 相似文献