Showing papers by "Research Triangle Park published in 1990"
TL;DR: Monitoring of cucumber plants inoculated with either tobacco necrosis virus or the fungal pathogen Colletotrichum lagenarium suggested that salicylic acid could function as the endogenous signal in the transmission of SAR in cucumber.
Abstract: In an effort to identify the signal compound that mediates systemic acquired resistance (SAR), changes in the content of phloem sap were monitored in cucumber plants inoculated with either tobacco necrosis virus or the fungal pathogen Colletotrichum lagenarium. The concentration of a fluorescent metabolite was observed to increase transiently after inoculation, with a peak reached before SAR was detected. The compound was purified and identified by gas chromatography-mass spectrometry as salicylic acid, a known exogenous inducer of resistance. The data suggest that salicylic acid could function as the endogenous signal in the transmission of SAR in cucumber.
987 citations
TL;DR: The results suggest that TGF-beta 1 may modulate metastatic potential of mammary tumor cells by controlling their ability to break down and penetrate basement-membrane barriers.
Abstract: The experimental metastatic potential of 13762NF mammary adenocarcinoma clone MTLn3 was tested after pretreatment in serum-free medium containing transforming growth factor (TGF) beta 1 at 0-5000 pg/ml. Lung colonies were measured 2 weeks after inoculation in syngeneic F344 rats, and a bell-shaped dose-response curve with 2- to 3-fold increase in number of surface lung metastases was seen. Maximal enhancement occurred at the 50 pg/ml dose level. The effect was specific because addition of neutralizing anti-TGF-beta antibody blocked the stimulatory activity at all levels of TGF-beta 1 pretreatment, but when antibody was given alone, neutralizing anti-TGF-beta antibody had no effect on untreated cells. Increased metastatic potential appears to be from an increased propensity of cells to extravasate as tested in the membrane invasion culture system. MTLn3 cells penetrated reconstituted basement-membrane barriers 2- to 3.5-fold more than did untreated control cells, depending upon length of TGF-beta 1 exposure. Increased invasive potential is apparently due, in part, to a 2- to 6-fold increase in type IV collagenolytic (gelatinolytic) and a 2.4-fold increase in heparanase activity. TGF-beta 1 treatment of MTLn3 cells did not alter their growth rate or morphology in the presence of serum; however, growth was inhibited in serum-free medium. Likewise, adhesion to human umbilical vein endothelial cell monolayers or to immobilized reconstituted basement membrane or fibronectin matrices was unchanged. These results suggest that TGF-beta 1 may modulate metastatic potential of mammary tumor cells by controlling their ability to break down and penetrate basement-membrane barriers.
405 citations
TL;DR: The purified human immunodeficiency virus integration protein, a potential target for selective antiviral therapy, was expressed in Escherichia coli and selectively cleaved double-stranded DNA oligonucleotides that mimic the U3 and the U5 termini of linear HIV DNA.
Abstract: The human immunodeficiency virus (HIV) integration protein, a potential target for selective antiviral therapy, was expressed in Escherichia coli. The purified protein, free of detectable contaminating endonucleases, selectively cleaved double-stranded DNA oligonucleotides that mimic the U3 and the U5 termini of linear HIV DNA. Two nucleotides were removed from the 3' ends of both the U5 plus strand and the U3 minus strand; in both cases, cleavage was adjacent to a conserved CA dinucleotide. The reaction was metal-ion dependent, with a preference for Mn2+ over Mg2+. Reaction selectivity was further demonstrated by the lack of cleavage of an HIV U5 substrate on the complementary (minus) strand, an analogous substrate that mimics the U3 terminus of an avian retrovirus, and an HIV U5 substrate in which the conserved CA dinucleotide was replaced with a TA dinucleotide. Such an integration protein-mediated cleavage reaction is expected to occur as part of the integration event in the retroviral life cycle, in which a double-stranded DNA copy of the viral RNA genome is inserted into the host cell DNA.
304 citations
TL;DR: The sequences encoding the cysteine-rich domain in class I chitinases are flanked by 9–10 bp imperfect direct repeats suggesting that these domains arose from a common ancestral gene and were introduced into genes for class I enzymes by transposition events.
Abstract: The endochitinases (E.C. 3.2.1.14, chitinase) are a structurally diverse group of enzymes believed to be important in the biochemical defense of plants against potential pathogens. The gene for a chitinase of Nicotiana tabacum L. cv. Havana 425 has been cloned and sequenced. The major transcription start is 11 bp upstream of the ATG codon and 28 bp downstream of the TATA box. The gene contains two introns and encodes a basic chitinase of 329 amino acids with a 23 amino acid N-terminal signal peptide followed by a 43 amino acid, cysteine-rich domain, which is linked by a hinge region to the main structure of the enzyme. This gene appears to be expressed because the exons are identical to the coding sequence of a cDNA which was isolated. Comparison of chitinase amino acid sequences from different plants indicates there are at least three classes of these enzymes: class I, basic chitinases with an N-terminal cysteine-rich domain and a highly conserved main structure; class II, chitinases similar to the main structure of class I chitinases but lacking the cysteine-rich domain; and, class III, chitinases with conserved sequences different from those of the class I and II enzymes. The sequences encoding the cysteine-rich domain in class I chitinases are flanked by 9-10 bp imperfect direct repeats suggesting that these domains arose from a common ancestral gene and were introduced into genes for class I enzymes by transposition events.
290 citations
TL;DR: Activity profiles are useful for the assessment of the available antimutagenesis data by providing rapid visualization of considerable dose information and experimental results.
Abstract: The concept of activity profile listings and plots, already applied successfully to the display of mutagenicity data, has been modified for application to antimutagenicity data. The activity profiles are bar graphs that have been organized in two general ways: for antimutagens that have been tested in combination with a given mutagen and for mutagens that have been tested in combination with a given antimutagen. Doses from both the mutagen and the antimutagen are displayed and plotted together with results on enhancement or inhibition of mutagenic activity. The short-term tests that have been used extensively to identify mutagens and potential carcinogens are increasingly being used to identify antimutagens and potential anticarcinogens. Three model mutagens, N -methyl- N ′-nitro- N -nitrosoguanidine, aflatoxin B 1 and benzo[ a ]pyrene, and 4 model antimutagens, butylated hydroxyanisole, butylated hydroxytoluene, glutathione and disulfiram, were selected from the data surveyed in the published literature. It is not clear at the present time whether the inhibition of carcinogen-induced mutation is a good indicator of anticarcinogenic properties, and further research is needed. Nevertheless, the activity profiles are useful for the assessment of the available antimutagenesis data by providing rapid visualization of considerable dose information and experimental results.
276 citations
TL;DR: The sources, modes, and levels of exposure to human populations, reproductive, behavioral, and neurotoxic effects, dermal effects, and most of the earlier data pertaining to its genotoxicity are revealed.
Abstract: (1990). Formaldehyde Toxicity—New Understanding. Critical Reviews in Toxicology: Vol. 20, No. 6, pp. 397-426.
250 citations
TL;DR: Data indicate an age-related decline in DNA repair competence among a small subpopulation of lymphocytes in lymphocytes exposed in vitro to 200 rads of X-irradiation.
Abstract: Previous biochemical studies on DNA repair competence and aging have been limited to techniques, such as alkaline elution or nucleoid sedimentation, involving mass cell populations. These techniques provide no information about the distribution of DNA damage and repair among individual cells and are unlikely to detect age-dependent changes affecting a minor fraction of the cell population. We have recently described a microgel electrophoretic assay (Singh et al., 1988) that measures, at the level of the individual cell, single-strand DNA breaks and alkali-sensitive sites. Here, we employ this method to analyze DNA damage and repair in lymphocytes isolated from the peripheral blood of 31 subjects (23 males and 8 females aged 25–91 years) and exposed in vitro to 200 rads of X-irradiation. While basal (pre-irradiation) levels of damage were independent of the age of the donor, an age-dependent increase in DNA damage was observed immediately following irradiation. For all subjects, the mean level of DNA damage was restored to pre-irradiation control levels within 2 h of incubation at 37°C. However, a distribution analysis of DNA damage among cells within each sample indicated the presence of a few highly damaged cells (4–16%) in the 2-h sample, the occurrence of which was significantly more common among aged individuals. These data indicate an age-related decline in DNA repair competence among a small subpopulation of lymphocytes.
227 citations
TL;DR: Why the teratogenic effects of TCDD are so highly species and tissue specific, and which animal species most accurately predicts the response of the human embryo/fetus, at the levels of exposure experienced by humans, still remains to be clarified.
Abstract: A specific teratogenic response is elicited in the mouse as a result of exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dioxin). The characteristic spectrum of structural malformations induced in mice following exposure to TCDD and structurally related congeners is highly reproducible and includes both hydronephrosis and cleft palate. In addition, prenatal exposure to TCDD has been shown to induce thymic hypoplasia. These three abnormalities occur at doses well below those producing maternal or embryo/fetal toxicity and are thus among the most sensitive indicators of dioxin toxicity. In all other laboratory species tested, TCDD causes maternal and embryo/fetal toxicity but does not induce a significant increase in the incidence of structural abnormalities even at toxic dose levels. Developmental toxicity occurs in a similar dose range across species; however, mice are particularly susceptible to development of TCDD-induced terata. Recent experiments using an organ culture were an attempt to address the issue of species and organ differences in sensitivity to TCDD. Human palatal shelves examined in this in vitro system were found to approximate the rat in terms of sensitivity for induction of cleft palate. Investigators have suggested that altered regulation of growth factors and their receptors may involve inappropriate proliferation and differentiation of target cells, ultimately producing TCDD-induced terata. Why the teratogenic effects of TCDD are so highly species and tissue specific, and which animal species most accurately predicts the response of the human embryo/fetus, at the levels of exposure experienced by humans, still remains to be clarified.
216 citations
TL;DR: Cell proliferation was increased in livers of both species of WY- and DCB-treated animals when compared to controls, and BRDU and [3H]-thymidine labeled the same population of cells as revealed by similar patterns of cell labeling in the livers and kidneys of treated animals.
Abstract: Different labeling methods for quantitating cell proliferation were evaluated in livers and kidneys of control and chemically treated mice and rats. The percentage of cells in S-phase (labeling indices) were compared in tissues of animals given either 5-bromo-2'-deoxyuridine (BRDU) or [3H]thymidine. These DNA precursor labels were delivered either by a single i.p. injection 2 h prior to killing the animals or via the s.c. implanted osmotic pump for 3 or 6 days. B6C3F1 mice and male F344 rats were exposed to either a peroxisome proliferator and hepatocarcinogen, Wy-14,643 (WY), in the diet at 0.1% for up to 5 days, or a non-genotoxic mouse liver and male rat kidney carcinogen, 1,4-dichlorobenzene (DCB), in corn oil by gavage for up to 5 days in mice (600 mg/kg/day) or up to 3 weeks in rats (300 mg/kg/day, 5 days per week). Labeling indices (LIs) in the liver and kidney were similar in BRDU- and [3H]thymidine-labeled mice and rats. Cell proliferation was increased in livers of both species of WY- and DCB-treated animals when compared to controls. After 4 days of chemical treatment with continuous administration of a DNA precursor label during the last 3 days of treatment, LIs in controls, DCB- and WY-treated mouse livers were 0.7, 19 and 17% for BRDU and 0.9, 15 and 13% for [3H]-thymidine respectively. Furthermore, BRDU and [3H]-thymidine labeled the same population of cells as revealed by similar patterns of cell labeling in the livers and kidneys of treated animals. The LI for BRDU- and [3H]thymidine-labeled renal proximal tubular cells was 7.7 and 8.0% respectively, in rats receiving DCB for 4 days and DNA precursor label during the last 3 days of treatment, while the LI for controls was 4.3 and 3.7% respectively. The renal proximal tubular cell LI increased to 11% in BRDU-labeled rats treated with DCB for 3 weeks. LIs in both liver and kidney were greatest in control and treated animals that received the DNA precursor label via osmotic pumps for 6 days, and least in 2 h pulse-labeled animals. However, induction of hepatic LI in treated over control animals was greatest for treated animals labeled for 3 days. These results demonstrate comparable cell labeling of cells in S-phase with either BRDU and [3H]thymidine labeling methods. BRDU presents no radioactive containment problems, and results are obtained more rapidly than [3H]thymidine.(ABSTRACT TRUNCATED AT 400 WORDS)
209 citations
TL;DR: This paper gives a systematic presentation of the literature related to closed queueing networks with finite queues and the results are significant for both researchers and practitioners.
Abstract: Closed queueing networks are frequently used to model complex service systems such as production systems, communication systems, computer systems, and flexible manufacturing systems. When limitations are imposed on the queue sizes (i.e., finite queues), a phenomenon called blocking occurs. Queueing networks with blocking are, in general, difficult to treat. Exact closed form solutions have been reported only in a few special cases. Hence, most of the techniques that are used to analyze such queueing networks are in the form of approximations, numerical analysis, and simulation. In this paper, we give a systematic presentation of the literature related to closed queueing networks with finite queues. The results are significant for both researchers and practitioners.
203 citations
TL;DR: The authors examined the sources of public opposition to a high-level nuclear waste repository among samples of 1001 residents of Nevada and a national sample of 1201 residents and found that the willingness of Nevada residents to accept a repository at Yucca Mountain depends upon subjective risk factors, especially the perceived seriousness of risk to future generations.
Abstract: This paper examines the sources of public opposition to a high-level nuclear waste repository among samples of 1001 residents of Nevada and a national sample of 1201 residents. Two models of choice are contrasted: A benefit-cost model and a risk-perception model of individual choice. The data suggest that the willingness of Nevada residents to accept a repository at Yucca Mountain depends upon subjective risk factors, especially the perceived seriousness of risk to future generations. Perceived risk depends in part on level of trust placed in the Department of Energy to manage a repository safely. Opposition to a local repository did not decrease significantly if compensation in the form of annual rebates, either ($1000, $3000, or $5000 per year for 20 years) were offered to residents. The public needs to be convinced before compensation is considered, that the repository will possess minimal risks to themselves as well as to future generations, and that the site currently targeted is suitable. One way to do this is through adoption of mitigation and control procedures such as strict federal standards and local control over the operation of the repository. The federal government should also consider returning to the fair procedure for selection between candidate sites specified in the initial Nuclear Waste Policy Act of 1982.
TL;DR: The rate of chain scission of PGLA was decreased and that of PCL and PLLA increased and a corresponding delay in the onset of weight loss was also observed.
TL;DR: The algorithm described in this paper is concerned with the first stage: given a list of nodes, an indication of the hierarchical relationship among them, and their shape and size, where should each node be positioned for optimal aesthetic effect?
Abstract: Drawing a tree consists of two stages: determining the position of each node, and actually rendering the individuals nodes and interconnecting branches. The algorithm described in this paper is concerned with the first stage: given a list of nodes, an indication of the hierarchical relationship among them, and their shape and size, where should each node be positioned for optimal aesthetic effect?
This algorithm determines the positions of the nodes for any arbitrary general tree. It is the most desirable positioning with respect to certain widely-accepted heuristics. The positioning, specified in x, y co-ordinates, minimizes the width of the tree. In a general tree, there is no limit on the number of offspring per node; this contrasts with binary and ternary trees, for example, which are trees with a limit of two and three offspring per node. This algorithm operates in time O(N), where N is the number of nodes in the tree.
Previously, most tree drawings have been positioned by the sure hand of a human graphic designer. Many computer-generated positionings have been either trivial or contained irregularities. Earlier work by Wetherell and Shannon1 and Tilford,2 upon which this algorithm builds, failed to position the interior nodes of some trees correctly. The algorithm presented here correctly positions a tree's node using only two passes. It also handles several practical considerations: alternative orientations of the tree, variable node sizes and out-of-bounds conditions. Radack,3 also building on Tilford's work, has solved this same problem with a different algorithm which makes four passes.
TL;DR: Rydberg and Johanson (1978) were the first to directly quantitate DNA damage in individual cells by lysing cells embedded in agarose on slides under mild alkali conditions to allow the partial unwinding of DNA.
Abstract: While providing information at the level of the individual cell, cytogenetic techniques for evaluating DNA damage or repair are, by their very nature, largely limited to proliferating cell populations. Furthermore, these techniques require the processing of DNA damage into microscopically visible lesions. Biochemical techniques, such as alkaline elution and nucleoid sedimentation, circumvent these difficulties in that DNA damage can be evaluated directly in almost any cell population. However, the resulting data do not provide any information about the distribution of damage or repair among individual cells. Since the effects of genotoxic agents are often tissue and cell-type specific, techniques which can directly detect DNA damage in individual cells are needed. Rydberg and Johanson (1978) were the first to directly quantitate DNA damage in individual cells by lysing cells embedded in agarose on slides under mild alkali conditions to allow the partial unwinding of DNA. After neutralization, the cells are stained with acridine orange and the extent of DNA damage quantitated by measuring the ratio of green (indicating double-stranded DNA) to red (indicating single-stranded DNA) fluorescence using a photometer.
TL;DR: Predictive assays and risk assessments for the numerous types of nongenotoxic carcinogens will require understanding of their mechanism of action, reasons for target organ and species specificity, and the quantitative dose-response relationships between endpoints such as induced cell proliferation and carcinogenic potential.
Abstract: Bacterial and cell culture genotoxicity assays have proven to be valuable in the identification of DNA reactive carcinogens because mutational events that alter the activity or expression of growth control genes are a key step in carcinogenesis. The addition of metabolizing enzymes to these assays have expanded the ability to identify agents that require metabolic activation. However, chemical carcinogenesis is a complex process dependent on toxicokinetics and involving at least steps of initiation, promotion and progression. Identification of those carcinogens that are activated in a manner unique to the whole animal, such as 2,6-dinitrotoluene, require in vivo genotoxicity assays. There are many different classes of non-DNA reactive carcinogens ranging from the potent promoter 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) that acts through a specific receptor, to compounds that alter growth control, such as phenobarbital. Many compounds, such as saccharin, appear to exhibit initiating, promotional and/or carcinogenic activity as events secondary to induced cytotoxicity and cell proliferation seen only at the chronic lifetime maximum tolerated doses mandated in rodent bioassays. Simple plus/minus vs. carcinogen/noncarcinogen comparisons used to validate the predictivity of bacterial and cell culture genotoxicity assays have revealed that a more comprehensive analysis will be required to account for the carcinogenicity of so many diverse chemical agents. Predictive assays and risk assessments for the numerous types of nongenotoxic carcinogens will require understanding of their mechanism of action, reasons for target organ and species specificity, and the quantitative dose-response relationships between endpoints such as induced cell proliferation and carcinogenic potential.
TL;DR: A class of curvilinear dose-response relationships in toxicological and epidemiological studies may be roughly described by "U-shaped" curves as discussed by the authors, which reflect an apparent reversal or inversion in the effect of an otherwise toxic agent at a low or intermediate region of the dose continuum.
Abstract: A class of curvilinear dose-response relationships in toxicological and epidemiological studies may be roughly described by "U-shaped" curves. Such curves reflect an apparent reversal or inversion in the effect of an otherwise toxic agent at a low or intermediate region of the dose continuum. Several examples of U-shaped dose-response functions are presented to illustrate the variety of agents and end points that can follow this form. Such findings are not thought to represent a unitary phenomenon, but may be explained through numerous possible principles or mechanisms, some of which are illustrated and discussed in general terms. U-shaped dose-response curves raise important issues for toxicological and environmental health risk assessments, particularly in the identification of no-observed-effect levels and in the evaluation of multiple outcomes and the tradeoffs between potential risks and benefits of a given agent. It is especially important to avoid focusing exclusively on an apparent improvement in one end point and failing to consider other, possibly deleterious effects of the same agent.
TL;DR: The metabolic activation of chloroform to toxic intermediates was shown to occur most rapidly in the mouse, less rapid in the rat, and most slowly in humans, consistent with previous reports.
TL;DR: The steps needed to implement this process and the results that may be obtained are discussed and insights into the nature of programming errors and the application of this process to a variety of working environments are discussed.
Abstract: Defect Prevention is the process of improving quality and productivity by preventing the injection of defects into a product. It consists of four elements integrated into the development process: (1) causal analysis meetings to identify the root cause of defects and suggest preventive actions; (2) an action team to implement the preventive actions; (3) kickoff meetings to increase awareness of quality issues specific to each development stage; and (4) data collection and tracking of associated data. The Defect Prevention Process has been successfully implemented in a variety of organizations within IBM, some for more than six years. This paper discusses the steps needed to implement this process and the results that may be obtained. Data on quality, process costs, benefits, and practical experiences are also presented. Insights into the nature of programming errors and the application of this process to a variety of working environments are discussed.
TL;DR: Comparison of amino acid sequences deduced from the cDNA clones and the sequence of peptides derived from purified proteins show that these clones encode the pathogenesis-related proteins PR-P and PR-Q, indicating that the induction of these proteins during the local necrotic lesion response to the virus is coordinated at the mRNA level.
Abstract: Complementary DNA clones encoding two isoforms of the acidic endochitinase (chitinase, EC 3.2.1.14) from tobacco were isolated. Comparison of amino acid sequences deduced from the cDNA clones and the sequence of peptides derived from purified proteins show that these clones encode the pathogenesis-related proteins PR-P and PR-Q. The cDNA inserts were not homologous to either the bacterial form of chitinase or the form from cucumber but shared significant homology to the basic form of chitinase from tobacco and bean. The acidic isoforms of tobacco chitinase did not contain the amino-terminal, cysteine-rich "hevein" domain found in the basic isoforms, indicating that this domain, which binds chitin, is not essential for chitinolytic activity. The accumulation of mRNA for the pathogenesis-related proteins PR-1, PR-R, PR-P, and PR-Q in Xanthi.nc tobacco leaves following infection with tobacco mosaic virus was measured by primer extension. The results indicate that the induction of these proteins during the local necrotic lesion response to the virus is coordinated at the mRNA level.
TL;DR: A markedly reduced risk for humans compared to male rats is suggested, because the nongenotoxic mechanism for carcinogenesis in the male rat involves a unique protein.
Abstract: alpha 2u-N is a syndrome that has been characterized in male rats exposed to a number of environmental chemicals and pharmacological agents. The chemicals or their metabolites bind to alpha 2u, which is believed to lead to a less digestible chemical-protein complex. Because of the decreased hydrolysis of the chemical-protein complex in the lysosome, alpha 2u accumulates in the form of protein droplets. In extensive nephropathy, the accumulation of alpha 2u in the lysosome results in polyangular crystalloid droplets that lead to lysosomal overload and eventually cell death. This cell death stimulates restorative cell replication which promotes renal carcinogenesis in male rats. As such, it is imperative that extrapolation of risk to humans of chemicals causing this syndrome be performed. Because the nongenotoxic mechanism for carcinogenesis in the male rat involves a unique protein, such extrapolations can only be done incorporating species differences in the critical factors that result in alpha 2u-N in rats. Presently, these data suggest a markedly reduced risk for humans compared to male rats.
TL;DR: Two similar direct-manipulation techniques are implemented, both of which use a map window—a miniature of the entire information space—with a wire-frame box to aid users in remembering their location.
Abstract: Often the components of a problem can be arrayed on a two-dimensional information space—for example, as an abstract tree or hypertext—far too large to fit onto a computer display. With current navigational techniques it is often difficult for users to keep track of their location or to move rapidly to remote locations in the space. We implemented two similar direct-manipulation techniques, both of which use a map window—a miniature of the entire information space—with a wire-frame box to aid users in remembering their location. The first technique allows the user to rapidly roam over the information space by moving the location of the wire-frame box. The second allows for zooming as well as roaming. A controlled experiment compared the above techniques to scroll bars for determining whether a target word was in a large balanced binary tree of words. The experiment also examined the merit of the map window. Map windows significantly improved user performance, and the roam and zoom techniques were ...
TL;DR: It is suggested that diffusible factors derived from damaged dopaminergic neurons initiate the astrocyte response to MPTP and that large increases in GFAP can be induced without the participation of serum-derived growth factor.
TL;DR: Studies of nasal airflow in rats and monkeys, using casting and molding techniques combined with a water-dye model, indicate that nasal airflow patterns are responsible for characteristic differences in the distribution of nasal lesions induced by formaldehyde in these species.
Abstract: The nasal passages of laboratory animals and man are complex, and lesions induced in the delicate nasal lining by inhaled air pollutants vary considerably in location and nature. The distribution o...
TL;DR: It is demonstrated that PMN counts in the NL can be a useful, inexpensive means of studying the acute inflammatory effect of ozone and monitoring those effects in the lower lung by comparison with the bronchoalveolar lavage taken from the same individual.
Abstract: Previously we established that an acute inflammatory response in the upper respiratory tract of humans could be studied by analyses of nasal lavages (NL). The relationship of these cellular responses to responses in the lower lung has not been thoroughly investigated in humans. In this study we have compared the cellular changes detected in NL with those detected in the bronchoalveolar lavage (BAL) taken from the same individual. A group of 10 subjects was exposed to either filtered air or 0.4 ppm ozone (O3), with exercise, for 2 h. The NL was done prior to, immediately following, and 18 h postexposure; the BAL was done only at 18 h postexposure. A significant increase in PMN was detected in the NL immediately postexposure to O3 (7.7-fold increase; p = 0.003) and remained elevated in the 18 h post-O3 NL (6.1-fold increase; p < 0.001). A similar increase in PMN was detected in the BAL 18 h after exposure to O3 (6.0-fold increase; p < 0.001). The albumin levels in the NL and BAL were also similarly increase...
TL;DR: Although NMDA-mediated potentiation may facilitate kindling, synaptic potentiation does not appear to be a critical requirement for kindling to develop, and the notion that development of the burst response and not synaptic enhancement may be the critical physiological alteration that underlies the kindling phenomenon is supported.
TL;DR: In this article, the catalytic effects of copper and iron compounds were examined for their behavior in promoting formation of chlorine (Cl2), the major chlorinating agent of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorined dibenzofurans (PCDFs), in an environment simulating that of municipal waste fly ash.
TL;DR: The subset of mRNAs present in the dendritic compartment may encode proteins involved in the morphogenesis and remodeling of dendrites, including MAP2, which is associated with the Triton X-100 insoluble fraction of the cell.
TL;DR: In this paper, the authors challenge common assumptions about convexity in forest rotation models which optimize timber plus nontimber benefits and show that policy based on marginal incentives may achieve suboptimal results if a local optimum occurs earlier than the globally optimal age.
TL;DR: In this article, the relationship of PTSD and its symptoms to violence in a sample of 1140 incarcerated male felons, most of whom did not develop PTSD or its symptoms from a combat-related traumatic stressor event was studied.
Abstract: Some previous research with Vietnam combat veterans has found a relationship to subsequent development of post-traumatic stress disorder (PTSD) and involvement in violent behavior. The relationship of PTSD and its symptoms to violence have not been studied in nonveteran samples. This article reports the relationship of PTSD and its symptoms to violence in a sample of 1140 incarcerated male felons, most of whom did not develop PTSD or its symptoms from a combat-related traumatic stressor event. A relationship of PTSD and its symptoms to arrest and incarceration for expressive violence is found when demographic, antisocial personality, and problem drinking factors are controlled. For the large majority of those who experienced at least one PTSD symptom and had an arrest history for expressive violence, the PTSD symptom preceded or occurred in the same year as the violence arrest. This temporal ordering is consistent with viewing PTSD symptoms as etiologically relevant to the occurrence of violence.
TL;DR: In this paper, exact analytical solutions of the Monin-Obukhoy stability parameters ζ=z/L, in terms of gradient Richardson number and bulk Richardson number (Rib), respectively, are obtained.
Abstract: Analytical solutions Of surface layer similarity equations are presented for the nondimensional profile functional forms suggested by Businger et al. For stable atmospheric conditions, exact analytical solutions of the Monin-Obukhoy stability parameters ζ=z/L, in terms of gradient Richardson number (Ri) and bulk Richardson number (Rib), respectively, are obtained. For unstable atmospheric conditions, an exact solution of the same in terms of Ri is found. An approximate relationship between ζ and Rib, for an unstable surface layer, based on the solution of ζ in terms of Ri, is suggested. The proposed analytical solutions can replace costly numerical iterative methods as well as some of the ad hoc parameterizations used for estimating surface fluxes and related turbulence characteristics.