bluuebunny/crossref_metadata_2025 huggingface dataset:
Cosolvent Influences on Organic Solute Retardation Factors
Authors: Staples Charles A. , Geiselmann Stephanie J.
Published: March 2006

Prediction of chemical movement in ground water can be complex. Solute transport calculations need to reflect appropriate mathematical treatment of sorption and retardation by aquifer materials. The presence of cosolvents further complicates solute transport prediction. Results from a series of experiments both simple (small tubes) and complex (soil columns) suggest adequate predictability of solute sorption and attenuation in the presence of cosolvents. The results indicate that simple (small tube) short‐term tests under a variety of sorbent concentrations can be used to predict soil column solute transport if appropriate physical properties are accounted for (soil type, organic load, bulk density). The final results indicate that low levels of cosolvents showed significant reproducible sorption/ attenuation reductions but probably are ultimately not important to overall solute fate.
Applying the USGS Mass‐Transport Model (MOC) to Remedial Actions by Recovery Wells
Authors: El‐Kadi Aly L.
Published: March 2006

The USGS two‐dimensional mass‐transport model (MOC) is widely used in the analysis of ground‐water contamination problems. A need exists to examine the accuracy of the code in situations dominated by radially convergent and divergent flow around wells. The model is applied here to situations that commonly exist in remedial actions involving recovery wells. The cases simulated are a recharge/recovery single well, a recharge/recovery doublet, and plume capture by one or two production wells. The results were tested against analytical and semianalytical solutions. Inaccuracies in model results occurred especially for the doublet case under continued long‐time simulation. Inaccuracies are caused not only by the mainly radial‐flow situation, or by the curvature nature of streamlines, but also by the arrival of contamination at the sink nodes. Better agreement of numerical and analytical solutions was obtained for the single‐well and plume‐capture situations. However, a large mass‐balance error exists for the single‐well case. Inaccuracies can be reduced by modifying the code and reducing the finite‐difference mesh (e.g., Erickson, 1985). However, the use of a very fine mesh (i.e., on the order of a few feet) may prevent the use of the code in large‐scale problems. Care must be taken in applying the model to situations where production or injection wells are close to each other.
An Optimization Model for Analysis of Test Pumping Data
Authors: Kashyap Deepak , Dachadesh Prasong , Jageshwar Sinha L. S.
Published: March 2006

An optimization model for computer‐assisted estimation of aquifer parameters has been developed. It is based upon the principle of minimization of the sum of squares of the differences between observed and computed drawdowns. The objective strategy eliminates the subjectivity associated with the conventional curve‐matching procedures. Apart from the parameter estimation, the model can assist in identifying certain hydrogeological features like leakage, discontinuities, vertical anisotropy, etc. It also can provide a check on consistency among different data sets monitored during a test pumping (e.g., drawdown and recovery data). The application of the proposed model has been illustrated by analysis of field data. The model‐computed parameters honored the observed data more closely than the graphical estimates. The model could also identify leakage as the cause of departure of the time‐drawdown curve from the Theis type curve. In another study, the model results lead to an inference that the recovery data of the pumped well are inconsistent with the rest of the data.
Finite‐Element Simulation of Long‐Term Transient Regional Ground‐Water Flow
Authors: England Lindy A. , Freeze R. Allan
Published: March 2006

A finite‐element model is developed to solve the two‐dimensional, transient, ground‐water flow equation on a regional scale over geologic time for the purpose of assessing the rate of hydraulic head decay at depth in response to erosional modifications of the land surface. The model includes a time‐stepping procedure that allows consideration of sedimentary basins with large hydraulic conductivity contrasts. Results confirm that hydraulic head patterns that are not in equilibrium with existing topography can persist at depth over geologically significant periods of time. A sensitivity analysis on a hypothetical layered system shows that the rate of hydraulic head adjustment, due to erosional modifications of the topography, is particularly sensitive to the thickness, continuity, and vertical hydraulic conductivity of the low‐permeability layers. Application of the two‐dimensional model to the Red earth region of northern Alberta, Canada predicts response times that are reduced by two‐thirds over those predicted with one‐dimensional models. The concept of delayed hydraulic response over geologic time has important implications in the siting and design of nuclear waste repositories, the analysis of contaminant plume migration, and the use of the hydrodynamic approach to the exploration for petroleum resources and stratabound ore deposits.
The Victoria Province Drought Relief Project, II. Borehole Yield Relationships
Authors: Houston J.F.T. , Lewis R. T.
Published: March 2006

Composite aquifers composed of relatively high storage, low permeability regolith overlying low storage, higher permeability fissured bedrock occur in the Basement terrain of Victoria Province. The adequacy of these aquifers for rural‐water supplies is variable and locating optimum borehole sites is difficult. The analysis of data from the Victoria Province Drought Relief Project suggests that a variety of environmental factors influence borehole yield. Despite the wide scatter of data, certain generalizations can be made using statistical techniques. The results show that for regolith aquifers specific capacity increases with rainfall, regolith thickness, and altitude, which is in turn probably related to the age of the erosion surface. In fissured bedrock aquifers the upper 20 m is crucial for the provision of an adequate yield.
Characterizing Jointed Systems by Azimuthal Resistivity Surveys
Authors: Taylor Robert W. , Fleming Anthony H.
Published: March 2006

Anisotropy, directional connectivity, and porosity of fracture systems can be estimated from surface azimuthal electrical resistivity surveys. Azimuthal resistivity surveys utilize conventional resistivity equipment and are performed by rotating a Wenner array about a fixed center point and measuring apparent resistivity as a function of azimuth. The depth of investigation is determined by the electrode spacing which is generally limited by practical considerations to approximately 70 m. The azimuthal survey generates an apparent resistivity ellipse from which the properties of a subsurface joint system can be determined. Theoretically the major axis of the resistivity ellipse will coincide with strike of the primary joint set. The ratio of major axis to minor axis of the ellipse defines the coefficient of anisotropy associated with the joints, and from this coefficient, secondary porosity can be calculated.

Application of azimuthal surveys at 60 sites in bedrock and clayey till throughout Wisconsin generally yielded joint strikes within a few degrees of direct observations. Porosities calculated for jointed bedrock are within a few percent of values determined by other methods. The absolute values of porosities calculated for the tills appear unreliable due to conduction effects along the surface of clay minerals.

Although the theoretical foundation for this technique is based on idealized jointing, the field results indicate that the method is effective in media with multiple joint sets. When mean joint length exceeds the electrode spacing, azimuthal resistivity peaks closely coincide with the mean strikes of observed joint sets. When joint lengths are less than the electrode spacing, the major ellipse axis indicates the most conductive path through the joint system. In both cases, ellipse shape indicates the direction (s) having the greatest joint connectivity, which are also the directions of greatest aquifer permeability.
AUTOMATED COMPUTATION OF PARAMETERS FOR LEAKY CONFINED AQUlFERSa
Authors: Mukhopadhyay Amitabha
Published: March 2006

Abstract. A FORTRAN program was developed to obtain the transmissivity, storage coefficient, and leakage factor for a leaky confined aquifer from pumping test data. The automated method computes the aquifer parameters faster and without bias when compared with the manual curvematching methods commonly used. Aquifer parameters obtained from published pumping test data using the software compare closely with those estimated by manual curve‐matching methods. The automated method cannot, however, detect the presence of recharge/discharge boundaries within the area of investigation or large deviations of data due to errors in data collection or data recording.
TRILINEAR DIAGRAM REVISITED: APPLICATION, LIMITATION, AND AN ELECTRONIC SPREADSHEET PROGRAM
Authors: Cheng Songlin
Published: March 2006

Abstract. The trilinear diagram has been used extensively in hydrochemical studies. The concept of hydrochemical facies based on the trilinear diagram can effectively characterize the chemical composition of water in a qualitative manner. However, its application is rather limited for quantitative and precise study, because it is difficult, if not impossible, to distinguish various mechanisms that may cause similar change in water chemistry by this diagram alone. This limitation is illustrated with various hypothetical water‐rock interactions and mixing trends plotted on the trilinear diagram.
Dichlorobenzene in Ground Water: Evidence for Long‐Term Persistence
Authors: Barber Larry B.
Published: March 2006

Hydrologic and geochemical evidence were used to establish the long‐term persistence of dichlorobenzene in ground water that has been contaminated from 50 years of rapid‐infiltration sewage disposal. An extensive plume of dichlorobenzene extends more than 3,500 meters down‐gradient from the disposal beds, with concentrations of the combined isomers ranging from less than 0.01 to over 1.0 μglL Based on estimates of maximum ground‐water flow velocities, a minimum age of 20 years was established for the farthest downgradient zone of dichlorobenzene contamination. Branched‐chained, alkylbenzenesulfonic acid surfactants, that were introduced into the ground water prior to 1966, occur along with dichlorobenzene in the downgradient part of the plume, further establishing residence of the compounds in the aquifer for at least 20 years. Although dichlorobenzene can be biologically degraded under aerobic conditions, its persistence at this field site is attributed to the dynamics of the ground‐water system. Denitrifying conditions, resulting from the degradation of organic compounds in the aquifer near the disposal beds, appear to have enhanced the persistence of dichlorobenzene, which is not degraded by anaerobic bacteria. Biological degradation of dichlorobenzene in the aerobic part of the plume downgradient from the source is probably limited by the paucity of a suitable organic‐carbon substrate and the low concentrations of dissolved oxygen in the contaminated ground water.
Conductivity Variations of Formation Waters in Coastal Alluvium, Andhra Pradesh, India
Authors: Subbaraoa C. , Satyanarayanab C.
Published: March 2006

Ground‐water samples'collected from wells in the coastal alluvial sediments of Andhra Pradesh near the Bay of Bengal have a large variation in conductivity values which can be related to chloride concentration and soil influence. In addition to spatial variation, there appears to be a relationship between the depth to ground‐water level and the conductivity of formation water. Wells with water levels above 3 m have a greater range of conductivity than those with water levels below 3 m.
Modifying the USGS Solute Transport Computer Model to Predict High‐Density Hydrocarbon Migration
Authors: Hossain M. Akhter , Corapcioglu M. Yavuz
Published: March 2006

Chlorinated hydrocarbons, such as trichloroethylene (TCE), trichloroethane (TCA), tetrachloroethylene (PCE), chloroform, and carbon tetrachloride enter soils and ground water from chemical waste disposal sites and from accidents. The migration of such high‐density hydrocarbons in a natural gradient unconfined gravel aquifer is studied. The Buckley‐Leverett approach is extended to a two‐dimensional case to simulate a high‐density immiscible hydrocarbon displacing ground water in a gravity‐driven system. Governing equations that were developed earlier by Corapcioglu and Hossain (1988) are solved by modifying the U.S.G.S. solute transport model (Konikow and Bredehoeft, 1978). The modification incorporates the fractional flow curves of water and their saturation derivatives in vertical and horizontal directions as functions of degree of water saturation. The details of the modification techniques are given, and the numerical results are presented for a hydrocarbon spill. Numerical results show that high‐density, low‐viscosity immiscible chlorinated hydrocarbons can travel deeper and further in contrast to lower‐density, higher‐viscosity compounds, and that the migration is dominated by gravity largely uncoupled from the horizontal component until the plume reaches the lower boundary.
Time Domain Electromagnetic Soundings for Mapping Sea‐Water Intrusion in Monterey County, California
Authors: Mills Theodore , Hoekstra Pieter , Blohm Mark , Evans Lauren
Published: March 2006

In November 1986, a surface geophysical survey was performed in Monterey County, California using Time Domain Electromagnetic (TDEM) soundings. Prior to this time, the Monterey County Flood Control and Water Conservation District had relied largely on water quality samples from monitoring wells to determine the extent of sea‐water intrusion in the Salinas Valley. This monitoring program had found that of the three aquifers in the study area, two aquifers, the “180‐ft” and the “400‐ft,” had been intruded. The third aquifer, the “900‐ft” aquifer, had not shown signs of sea‐water intrusion. The District decided to use surface geophysics to obtain information about water quality between monitoring wells and to contour the position of the 500‐ppm isochlor in both of the upper aquifers.

Because the conductivity of water increases with chloride concentration, electrical methods are well‐suited for mapping chloride concentration in ground water. The TDEM sounding method was selected as the surface electrical measurement technique. It had proven successful for mapping interfaces between fresh water and salt water on surveys in Cape Cod, Massachusetts, in several areas in Florida, and in southern California. A total of 100 soundings were measured in the project area, requiring three weeks of field work. The soundings were located by using the information available from monitoring wells. Lines of soundings were run approximately perpendicular to the anticipated position of the 500‐ppm isochlor to better define the location of the isochlor.

Several soundings were measured adjacent to wells to aid in correlating the geophysical interpretations to known water quality data. By correlating the surface geophysics to water quality data from monitoring wells, the position of the 500‐ppm isochlor could be mapped in both the “180‐ft” and “400‐ft” aquifer.

The positions of the contours of the 500‐ppm isochlor derived from monitoring wells and from 100 TDEM soundings show excellent agreement. There is more local detail in the isochlor contours derived from geophysical interpretations than in the contours derived from monitoring wells, mainly because of the higher TDEM stations density.
Radon Distribution in Domestic Water of Texas
Authors: Cech Irina , Kreitler Charles , Prichard Howard , Holguin Alfonso , Lemma Mengistu
Published: March 2006

Concern is mounting over possible adverse health effects associated with exposure to elevated domestic alpha radiation levels (Bean et al, 1982); Petersen et al., 1966; Lyman et al, 1985; Cothern, 1987). Radon released during domestic use of ground water is one of the potential routes of such exposure. However, relatively little is known worldwide about the distribution of alpha‐emitting radioisotopes in ground‐water supplies. In Texas, deposits of uranium occur, rich enough to be mined commercially, and the possibility existed that significant concentrations of uranium disintegration products may have been present in ground‐water supplies. Cech et al. (1987a) identified two regions with anomalously high concentrations of radium‐226: in the Gulf Coast, downdip from uranium deposits, and in west‐central Texas, on the periphery of an igneous uplift. Radium‐226 is a parent of radon‐222 which is a focus of the present paper. Concentrations of radon up to 3300 pCi/1 were observed in several domestic‐water supplies. This study suggests that it may be external sources (interaction of Tertiary aquifers with salt domes, leaky faults, and uranium‐bearing volcanic ashes) and not the bulk mineralogy of the aquifers, which cause anomalous concentrations of alpha‐emitting radioisotopes in well water. The distinction is important, as it offers the possibility of avoiding high risk areas when selecting well drilling locations.
The Recharge‐Discharge Function of Wetlands Near Juneau, Alaska: Part II. Geochemical Investigations
Authors: Siegel D. I.
Published: March 2006

The recharge‐discharge function of bogs, fens, and forested wetlands near Juneau, Alaska, was investigated by comparing concentrations of solutes and measurements of specific conductance in wetland ground water and surface water. Average concentrations of major metals define major wetland types. Bogs and fens are in recharge areas and have the most dilute ground water. Forested wetlands are in discharge areas and have ground‐water chemistry similar to that found in domestic wells completed in mineral soils.

Concentration profiles of total dissolved metals in blanket bogs were compared to theoretical concentration profiles based on the diffusion of solutes from mineral soil into the overlying peat. All observed concentration profiles are less than predicted by diffusion, and show that the blanket bogs are long‐term recharge zones.
Interpretation of Well and Field Data in a Heterogeneous Layered Aquifer Setting, Appalachian Plateau
Authors: Booth Colin J.
Published: March 2006

Ground‐water flow systems in the Appalachian Plateau coalfield balance the conflicting controls of topographic relief and hydrostratigraphic layering. Appropriate use of field observations (springs, streams) and abundant domestic well information (water levels, pumping test results, records of yield, and water‐producing zones) helped resolve ambiguities about a typical system in Cambria County, Pennsylvania. The effective scale for hydrostratigraphic division is by sandstone‐dominated members as aquifers and intervening shale‐clay members as aquitards. The flow system is stratified in the intervalley ridges; heads, controlled primarily by the dissected aquifer outcrop, drop discretely to lower aquifers. Discrete ground‐water discharge and lateral head changes indicate local heterogeneity, enhanced by mine‐subsidence effects. The principal valleys carry a topographically controlled system, for which they serve as recharge feeders.
Numerical Modeling of Salt‐Water Intrusion at Hallandale, Florida
Authors: Andersen Peter F. , Mercer James W. , White Harold O.
Published: March 2006

The City of Hallandale, located on the east coast of Florida, has documented over the past decade an increase in chloride in the monitoring well network surrounding its wellfield. Data indicate that the salt‐water front is currently located within 1,200 ft of the wellfield and is still moving inland. Suspected causes of the intrusion are: (1) increased pumpage by Hallandale, (2) increased pumpage from neighboring wellfields, (3) cumulative deficiency in rainfall over the past decade, and (4) reduction of canal stages that control water‐table elevations. The inability of standard methods to characterize the salt‐water intrusion led to the use of numerical modeling to aid in understanding the processes occurring at Hallandale. A series of three models were used in the study. A cross‐sectional model was used to conceptualize the flow system, and a regional model synthesized input for the third model, the wellfield model. The wellfield model was eventually used to assess the relative merits of proposed water management alternatives. Although the modeling did not isolate a specific cause of the intrusion, it did show the extreme sensitivity of the hydrologic system. Long‐term water‐level declines of only a few tenths of a foot were shown to result in a significant movement of the salt‐water front. There is a distinct time lag, however, between lowering of the hydraulic heads and movement of the salt‐water front, which has many implications for water management decisions and in the construction and calibration of a numerical model. These observations, as well as others made in the course of this study, can be applied generally to coastal water management programs.
THREE‐DIMENSIONAL, CROSS‐SEMIVARIOGRAM CALCULATIONS FOR HYDROGEOLOGICAL DATA
Authors: Lstok Jonathan D. , Cooper Richard M. , Flint Alan L.
Published: March 2006

Abstract. Geostatistics is a powerful tool for the analysis of hydrogeological data, but few well‐documented computer programs for performing the necessary calculations have been presented in the technical literature. This is especially true for applications that require either three‐dimensional or multivariate analyses. This paper describes a FORTRAN subroutine, VARIO, that can be used to compute experimental direct‐ and cross‐semivariograms from a set of sample data, for any specified direction in one‐, two‐, or three‐dimensional space. The subroutine combines into groups those sample pairs that fall within predetermined angular tolerances of the specified direction. The number of sample pairs used to compute the value of the experimental semivariogram at each value of separation can be specified in four different ways, depending on the nature of the available data. Written in FORTRAN 77, VARIO can be used on any computer that supports a FORTRAN 77 compiler. Source code listing, user instructions, and example input and output data for VARIO are presented.
Phosphoinositide, Phosphopeptide and Pyridone Interactions of the Abl SH2 Domain
Authors: Tokonzaba Etienne , Capelluto Daniel G. S. , Kutateladze Tatiana G. , Overduin Michael
Published: March 2006

Signaling proteins are localized and regulated by Src homology 2 domains which recognize phosphotyrosine‐containing sequences. Recently, noncanonical ligands have been proposed for Src homology 2 domains including that of Abl and its breakpoint cluster region fusion, which causes chronic myelogenous leukemia. Here, the Abl Src homology 2 domain's binding sites and affinities for phosphotyrosine‐ and phosphoserine‐containing motifs, phosphoinositides as well as a pyridone‐based peptidomimetic inhibitor were determined using nuclear magnetic resonance spectroscopy in order to define their roles. The cognate Crk peptide ligand was bound with an affinity of 69 μM and, like the higher affinity peptidomimetic, engages the phosphotyrosine and +3 hydrophobic pockets while putative phosphoserine‐containing breakpoint cluster region ligands are ruled out. Surprisingly, phosphatidylinositol 4, 5 bisphosphate interacts with an overlapping site through an electrostatic mechanism that does not appear to involve hydrophobic insertion into micelles. The conserved Arg36 residue in the FLVRES motif is required for both phosphotyrosine binding and for localization to phosphatidylinositol 4, 5 bisphosphate–containing liposomes, while Arg59 in theβD strand is necessary for the phosphoinositide interaction. Thus the Src homology 2 domain of Abl, a myristoylated and membrane‐localized protein, is able to interact directly with phosphoinositides through a multifunctional basic site that overlaps the phosphotyrosine pocket.
Teaching Image Formation by a Lens
Authors: Gluck Paul
Published: March 2006

Geometrical optics followed by wave optics is the traditional sequence in an introductory course. Apart from discussing the conditions for the validity of each regime, little attention is normally paid to the insights that physical optics can provide in geometrical optics, except for the diffraction-limited resolving power of instruments by means of the Rayleigh criterion. Yet, everything one can prove with rays can (and should?) be shown using the wave picture together with the Huygens construction, be it the laws of refraction and refraction, the thin lens, or the lens maker's formulae.
Infection withPlasmodium bergheiBoosts Antibody Responses Primed by a DNA Vaccine Encoding Gametocyte Antigen Pbs48/45
Authors: Haddad Diana , Maciel Jorge , Kumar Nirbhay
Published: March 2006

An important consideration in the development of a malaria vaccine for individuals living in areas of endemicity is whether vaccine-elicited immune responses can be boosted by natural infection. To investigate this question, we usedPlasmodium bergheiANKA blood-stage parasites for the infection of mice that were previously immunized with a DNA vaccine encoding theP. bergheisexual-stage antigen Pbs48/45. Intramuscular immunization in mice with one or two doses of DNA-Pbs48/45 or of empty DNA vaccine as control did not elicit detectable anti-Pbs48/45 antibodies as determined by enzyme-linked immunosorbent assay. An infection withP. bergheiANKA 6 weeks after DNA vaccination elicited comparable anti-Pbs48/45 antibody levels in mice which had been primed with DNA-Pbs48/45 or with empty DNA vaccine. However, a repeat infection withP. bergheiANKA resulted in significantly higher anti-Pbs48/45 antibody levels in mice which had been primed with the DNA-Pbs48/45 vaccine than the levels in the mock DNA-vaccinated mice. In parallel and as an additional control to distinguish the boosting of Pbs48/45 antibodies exclusively by gametocytes during infection, a separate group of mice primed with DNA-Pbs48/45 received an infection withP. bergheiANKA clone 2.33, which was previously described as a “nongametocyte producer.” To our surprise, this parasite clone too elicited antibody levels comparable to those induced by theP. bergheigametocyte producer clone. We further demonstrate that the nongametocyte producerP. bergheiclone is in fact a defective gametocyte producer that expresses Pbs48/45, much like the gametocyte producer clone, and is therefore capable of boosting antibody levels to Pbs48/45. Taken together, these results indicate that vaccine-primed antibodies can be boosted during repeat infections and warrant further investigation with additional malaria antigens.
Contribution of Hemagglutinin/Protease and Motility to the Pathogenesis of El Tor Biotype Cholera
Authors: Silva Anisia J. , Leitch Gordon J. , Camilli Andrew , Benitez Jorge A.
Published: March 2006

Vibrio cholerae
is a highly motile organism that secretes a Zn-dependent metalloprotease, hemagglutinin/protease (HapA). HapA has been shown to have mucinase activity and contribute to the reactogenicity of live vaccine candidates, but its role in cholera pathogenesis is not yet clear. The contribution of motility to pathogenesis is not fully understood, since conflicting results have been obtained with different strains, mutants, and animal models. The objective of this work was to determine the contribution of HapA and motility to the pathogenesis of El Tor biotype cholera. To this end we constructed isogenic motility (
motY
) and mucinase (
hapA
) single and double mutants of an El Tor biotype
V. cholerae
strain. Mutants were characterized for the expression of major virulence factors in vitro and in vivo. The motility mutant showed a remarkable increase in cholera toxin (CT), toxin coregulated pilus major subunit (TcpA), and HapA production in vitro. Increased TcpA and CT production could be explained by increased transcription of
tcpA
,
ctxA
, and
toxT
. No effect was detected on the transcription of
hapA
in the motility mutant. The sodium ionophore monensin diminished production of HapA in the parent but not in the motility mutant. Phenamil, a specific inhibitor of the flagellar motor, diminished CT production in the wild-type and
motY
strains. The
hapA
mutant showed increased binding to mucin. In contrast, the
motY
mutation diminished adherence to biotic and abiotic surfaces including mucin. Lack of HapA did not affect colonization in the suckling mouse model. The motility and mucinase defects did not prevent induction of
ctxA
and
tcpA
in the mouse intestine as measured by recombinase-based in vivo expression technology. Analysis of mutants in the rabbit ileal loop model showed that both
V. cholerae
motility and HapA were necessary for full expression of enterotoxicity.
Genetic Resistance toBrucella abortusin the Water Buffalo (Bubalus bubalis)
Authors: Borriello Giorgia , Capparelli Rosanna , Bianco Michele , Fenizia Domenico , Alfano Flora , Capuano Federico , Ercolini Danilo , Parisi Antonio , Roperto Sante , Iannelli Domenico
Published: March 2006

Brucellosis is a costly disease of water buffaloes (Bubalus bubalis). Latent infections and prolonged incubation of the pathogen limit the efficacy of programs based on the eradication of infected animals. We exploited genetic selection for disease resistance as an approach to the control of water buffalo brucellosis. We tested 231 water buffalo cows for the presence of anti-Brucella abortusantibodies (by the agglutination and complement fixation tests) and theNramp1genotype (by PCR-denaturing gradient gel electrophoresis). When the 231 animals (58 cases and 173 controls) were divided into infected (seropositive) and noninfected (seronegative) groups and theNramp1genotypes were compared, the seropositive subjects were 52 out of 167 (31%) in theNramp1A+(Nramp1AAorNramp1AB) group and 6 out of 64 (9.4%) in theNramp1A−(Nramp1BB) group (odds ratio, 4.37; 95% confidence limits, 1.87 to 10.19; χ2, 11.65 for 1 degree of freedom). Monocytes fromNramp1BBsubjects displayed significantly (P< 0.01) higher levels ofNramp1mRNA thanNramp1AAsubjects and also a significantly (P< 0.01) higher ability in controlling the intracellular replication of severalBrucellaspecies in vitro. Thus, selection for theNramp1BBgenotype can become a valuable tool for the control of water buffalo brucellosis in the areas where the disease is endemic.
NF-κB-Inducing Kinase Regulates Selected Gene Expression in the Nod2 Signaling Pathway
Authors: Pan Qilin , Kravchenko Vladimir , Katz Alex , Huang Shuang , Ii Masayuki , Mathison John C. , Kobayashi Koichi , Flavell Richard A. , Schreiber Robert D. , Goeddel David , Ulevitch Richard J.
Published: March 2006

The innate immune system surveys the extra- and intracellular environment for the presence of microbes. Among the intracellular sensors is a protein known as Nod2, a cytosolic protein containing a leucine-rich repeat domain. Nod2 is believed to play a role in determining host responses to invasive bacteria. A key element in upregulating host defense involves activation of the NF-κB pathway. It has been suggested through indirect studies that NF-κB-inducing kinase, or NIK, may be involved in Nod2 signaling. Here we have used macrophages derived from primary explants of bone marrow from wild-type mice and mice that either bear a mutation in NIK, rendering it inactive, or are derived from NIK
−/−
mice, in which the NIK gene has been deleted. We show that NIK binds to Nod2 and mediates induction of specific changes induced by the specific Nod2 activator, muramyl dipeptide, and that the role of NIK occurs in settings where both the Nod2 and TLR4 pathways are activated by their respective agonists. Specifically, we have linked NIK to the induction of the B-cell chemoattractant known as BLC and suggest that this chemokine may play a role in processes initiated by Nod2 activation that lead to improved host defense.
Reduced Protective Efficacy of a Blood-Stage Malaria Vaccine by Concurrent Nematode Infection
Authors: Su Zhong , Segura Mariela , Stevenson Mary M.
Published: March 2006

Helminth infections, which are prevalent in areas where malaria is endemic, have been shown to modulate immune responses to unrelated pathogens and have been implicated in poor efficacy of malaria vaccines in humans. We established a murine coinfection model involving blood-stage
Plasmodium chabaudi
AS malaria and a gastrointestinal nematode,
Heligmosomoides polygyrus
, to investigate the impact of nematode infection on the protective efficacy of a malaria vaccine. C57BL/6 mice immunized with crude blood-stage
P. chabaudi
AS antigen in TiterMax adjuvant developed strong protection against malaria challenge. The same immunization protocol failed to induce strong protection in
H. polygyrus
-infected mice. Immunized nematode-infected mice produced significantly lower levels of malaria-specific antibody than nematode-free mice produced. In response to nematode and malarial antigens, spleen cells from immunized nematode-infected mice produced significantly lower levels of gamma interferon but more interleukin-4 (IL-4), IL-13, and IL-10 in vitro than spleen cells from immunized nematode-free mice produced. Furthermore,
H. polygyrus
infection also induced a strong transforming growth factor β1 response in vivo and in vitro. Deworming treatment of
H. polygyrus
-infected mice before antimalarial immunization, but not deworming treatment after antimalarial immunization, restored the protective immunity to malaria challenge. These results demonstrate that concurrent nematode infection strongly modulates immune responses induced by an experimental malaria vaccine and consequently suppresses the protective efficacy of the vaccine against malaria challenge.
Immunomodulation with CD40 Stimulation and Interleukin-2 Protects Mice from Disseminated Cryptococcosis
Authors: Zhou Qing , Gault Ruth A. , Kozel Thomas R. , Murphy William J.
Published: March 2006

Cryptococcus neoformansis a ubiquitous fungus that can cause life-threatening infections during immunosuppressive states such as AIDS and after bone marrow transplantation. In this study we investigated the antifungal efficacy of an agonist antibody to CD40, an important costimulator of immune function, in combination with interleukin 2 (IL-2) in a murine model of disseminated cryptococcosis. Only the combination of anti-CD40 and IL-2 significantly prolonged the survival time of infected mice. This protection was correlated with decreased yeast burdens in the brain and kidney. Increased immune cell populations in the spleens, as well as increased serum gamma interferon (IFN-γ) and tumor necrosis factor alpha levels were observed in infected mice treated with anti-CD40 and IL-2. Further experiments with IFN-γ knockout mice demonstrated that the protection induced by anti-CD40 and IL-2 treatment was dependent on IFN-γ. Depletion of CD4+T cells did not affect the increased serum IFN-γ levels induced by anti-CD40 and IL-2 treatment and, importantly, did not affect the antifungal effect of combination therapy. These studies indicate that immunotherapy using anti-CD40 and IL-2 has therapeutic potential in augmenting host resistance to disseminated cryptococcosis and that IFN-γ is essential for efficacy.
Immunization of Aged Mice with a Pneumococcal Conjugate Vaccine Combined with an Unmethylated CpG-Containing Oligodeoxynucleotide Restores Defective Immunoglobulin G Antipolysaccharide Responses and Specific CD4+-T-Cell Priming to Young Adult Levels
Authors: Sen Goutam , Chen Quanyi , Snapper Clifford M.
Published: March 2006

Polysaccharide (PS)-protein conjugate vaccines, in contrast to purified PS vaccines, recruit CD4+-T-cell help and restore defective PS-specific humoral immunity in the immature host. Surprisingly, in the immunocompromised, aged host, anti-PS responses to conjugate vaccines are typically no better than those elicited by purified PS vaccines. Although aging leads to defects in multiple immune cell types, diminished CD4+-T-cell helper function has recently been shown to play a dominant role. We show that in response to immunization with purified pneumococcal capsular PS serotype 14 (PPS14) in saline, the T-cell-independent immunoglobulin G (IgG) anti-PPS14 response in aged mice was comparable to that in young mice. In contrast, the T-cell-dependent IgG anti-PPS14 response to a soluble conjugate of PPS14 and pneumococcal surface protein A (PspA) (PPS14-PspA) in saline was markedly defective. This was associated with defective priming of PspA-specific CD4+T cells. In contrast, immunization of aged mice with PPS14-PspA combined with an unmethylated CpG-containing oligodeoxynucleotide (CpG-ODN) restored IgG anti-PPS14 responses to young adult levels, which were substantially higher than those observed using purified PPS14. This was associated with enhanced PspA-specific CD4+-T-cell priming. Similarly, intactStreptococcus pneumoniaecapsular type 14, which contains Toll-like receptor (TLR) ligands, also induced substantial, though modestly reduced, T-cell-dependent (TD) IgG ant-PPS14 responses in aged mice. Spleen and peritoneal cells from aged and young adult mice made comparable levels of proinflammatory cytokines in response to CpG-ODN, although cells from aged mice secreted higher levels of interleukin-10. Collectively, these data suggest that inclusion of a TLR ligand, as an adjuvant, with a conjugate vaccine can correct defective TD IgG anti-PS responses in elderly patients by augmenting CD4+-T-cell help.
Antibody-Independent, Interleukin-17A-Mediated, Cross-Serotype Immunity to Pneumococci in Mice Immunized Intranasally with the Cell Wall Polysaccharide
Authors: Malley Richard , Srivastava Amit , Lipsitch Marc , Thompson Claudette M. , Watkins Claire , Tzianabos Arthur , Anderson Porter W.
Published: March 2006

Serotype-specific immunity toStreptococcus pneumoniaeis conferred by antibodies to the capsular polysaccharides, which define the 90 known serotypes. Whether antibody to the species-common cell wall polysaccharide (C-Ps) is protective has been a matter of controversy. Here we show that C-Ps given intranasally with mucosal adjuvant increased the resistance of mice to experimental nasopharyngeal colonization by capsulatedS. pneumoniaeof serotype 6B. This immunity could be induced in mice congenitally lacking immunoglobulin but was dependent upon CD4+T cells. Elimination of the charged amino group on the polymer backbone by N acetylation of C-Ps reduced the immunity, as did treatment of the mice with antibody to the cytokine interleukin-17A at the time of challenge, both consistent with the hypothesis of T-cell activation due to the zwitterionic motif of the polymer. C-Ps also protected in a model of fatal aspiration pneumonia by heavily capsulated serotype 3. These findings suggest a novel immunization strategy againstS. pneumoniae.
Genomic Comparison of
Escherichia coli
K1 Strains Isolated from the Cerebrospinal Fluid of Patients with Meningitis
Authors: Yao Yufeng , Xie Yi , Kim Kwang Sik
Published: March 2006

Escherichia coli
is a major cause of enteric/diarrheal diseases, urinary tract infections, and sepsis.
E. coli
K1 is the leading gram-negative organism causing neonatal meningitis, but the microbial basis of
E. coli
K1 meningitis is incompletely understood. Here we employed comparative genomic hybridization to investigate 11 strains of
E. coli
K1 isolated from the cerebrospinal fluid (CSF) of patients with meningitis. These 11 strains cover the majority of common O serotypes in
E. coli
K1 isolates from CSF. Our data demonstrated that these 11 strains of
E. coli
K1 can be categorized into two groups based on their profile for putative virulence factors, lipoproteins, proteases, and outer membrane proteins. Of interest, we showed that some open reading frames (ORFs) encoding the type III secretion system apparatus were found in group 2 strains but not in group 1 strains, while ORFs encoding the general secretory pathway are predominant in group 1 strains. These findings suggest that
E. coli
K1 strains isolated from CSF can be divided into two groups and these two groups of
E. coli
K1 may utilize different mechanisms to induce meningitis.
Identification of a Two-Partner Secretion Locus of Enterotoxigenic
Escherichia coli
Authors: Fleckenstein James M. , Roy Koushik , Fischer Julia F. , Burkitt Michael
Published: March 2006

Enterotoxigenic
Escherichia coli
(ETEC) remains a formidable cause of diarrheal illness worldwide. At present, there is no vaccine that provides broad-based protection against ETEC. A ′
phoA
-based self-cloning mutagenesis system, Tn
phoA
.ts, employed to identify novel ETEC surface antigens, led to identification of an
E
TEC
t
wo-
p
artner secretion locus (
etpBAC
) on the pCS1 virulence plasmid of prototype strain H10407. Cloning and expression of
etpBAC
in recombinant
E. coli
LMG194(pJY019) resulted in secretion of a high-molecular-weight (HMW) glycosylated exoprotein. This glycoprotein, EtpA, exhibits linear peptide sequence and predicted structural homologies with known HMW adhesins produced by other two-partner secretion loci. Antibodies directed against recombinant EtpA (anti-rEtpA.6H) recognized an HMW protein in culture supernatants of ETEC strains H10407 and LMG194(pJY019) but not in culture supernatant of strain H10407-P, which lacks the 92-kb pCS1 plasmid, or an isogenic
etpA
mutant.
etpA
mutants were deficient in adherence to intestinal epithelial cells in vitro, and anti-rEtpA.6H antibodies inhibited association of H10407 with target epithelial cells. Cloning and expression of
etpB
in recombinant
E. coli
were sufficient to confer adherence. Screening of multiple ETEC isolates for the
etpBAC
locus by colony hybridization and by EtpA immunoblotting suggested that EtpA is one of the most common antigens secreted by these pathogens. Together, these results indicate that the newly identified ETEC two-partner secretion locus directs the secretion of a high-molecular-weight glycosylated protein, EtpA, that in concert with the putative EtpB transporter participates in adherence of H10407 to epithelial cells, thereby expanding the repertoire of potential ETEC virulence proteins and vaccine candidates.
The Cholera Toxin A1
3
Subdomain Is Essential for Interaction with ADP-Ribosylation Factor 6 and Full Toxic Activity but Is Not Required for Translocation from the Endoplasmic Reticulum to the Cytosol
Authors: Teter Ken , Jobling Michael G. , Sentz Danielle , Holmes Randall K.
Published: March 2006

Cholera toxin (CT) moves from the plasma membrane to the endoplasmic reticulum (ER) by retrograde vesicular traffic. In the ER, the catalytic CTA1 polypeptide dissociates from the rest of the toxin and enters the cytosol by a process that involves the quality control mechanism of ER-associated degradation (ERAD). The cytosolic CTA1 then ADP ribosylates Gsα, resulting in adenylate cyclase activation and intoxication of the target cell. It is hypothesized that the C-terminal A1
3
subdomain of CTA1 plays two crucial roles in the intoxication process: (i) it contains a hydrophobic domain that triggers the ERAD mechanism and (ii) it facilitates interaction with the cytosolic ADP-ribosylation factors (ARFs) that serve as allosteric activators of CTA1. In this study, we examined the role(s) of the CTA1
3
subdomain in CT intoxication. Full-length CTA1 constructs and truncated CTA1 constructs lacking the A1
3
subdomain were generated and used to conduct two-hybrid studies of interactions with ARF6, in vitro enzyme assays, in vivo toxicity assays, and in vivo processing/degradation assays. Direct, plasmid-mediated expression of CTA1 constructs in the ER or cytosol of transfected CHO cells was used to perform the in vivo assays. With these methods, we found that the A1
3
subdomain of CTA1 is important both for interaction with ARF6 and for full expression of enzyme activity in vivo. Surprisingly, however, the A1
3
subdomain was not required for ERAD-mediated passage of CTA1 from the ER to the cytosol. A possible alternative trigger for CTA1 to activate the ERAD mechanism is discussed.
Importance of Nitric Oxide Synthase in the Control of Infection by
Bacillus anthracis
Authors: Raines Kimberly W. , Kang Tae Jin , Hibbs Stephen , Cao Guan-Liang , Weaver John , Tsai Pei , Baillie Les , Cross Alan S. , Rosen Gerald M.
Published: March 2006

The spore-forming, gram-positive bacterium
Bacillus anthracis
, the causative agent of anthrax, has achieved notoriety due to its use as a bioterror agent. In the environment,
B. anthracis
exists as a dormant endospore. Upon infection, germination of endospores occurs during their internalization within the phagocyte, and the ability to survive exposure to antibacterial killing mechanisms, such as O
2
·−
, NO
·
, and H
2
O
2
, is a key initial event in the infective process. Macrophages generate NO
·
from the oxidative metabolism of
l
-arginine, using an isoform of nitric oxide synthase (NOS 2). Exposure of murine macrophages (RAW264.7 cells) to
B. anthracis
endospores up-regulated the expression of NOS 2 12 h after exposure, and production of NO
·
was comparable to that achieved following other bacterial infections. Spore-killing assays demonstrated a NO
·
-dependent bactericidal response that was significantly decreased in the presence of the NOS 2 inhibitor
l
-
N
6
-(1-iminoethyl)lysine and in
l
-arginine-depleted media. Interestingly, we also found that
B. anthracis
bacilli and endospores exhibited arginase activity, possibly competing with host NOS 2 for its substrate,
l
-arginine. As macrophage-generated NO
·
is an important pathway in microbial killing, the ability of endospores of
B. anthracis
to regulate production of this free radical has important implications in the control of
B. anthracis
-mediated infection.
Immunization with a Circumsporozoite Epitope Fused to
Bordetella pertussis
Adenylate Cyclase in Conjunction with Cytotoxic T-Lymphocyte-Associated Antigen 4 Blockade Confers Protection against
Plasmodium berghei
Liver-Stage Malaria
Authors: Tartz Susanne , Kamanova Jana , Simsova Marcela , Sebo Peter , Bolte Stefanie , Heussler Volker , Fleischer Bernhard , Jacobs Thomas
Published: March 2006

The adenylate cyclase toxoid (ACT) of
Bordetella pertussis
is capable of delivering its N-terminal catalytic domain into the cytosol of CD11b-expressing professional antigen-presenting cells such as myeloid dendritic cells. This allows delivery of CD8
+
T-cell epitopes to the major histocompatibility complex (MHC) class I presentation pathway. Recombinant detoxified ACT containing an epitope of the
Plasmodium berghei
circumsporozoite protein (CSP), indeed, induced a specific CD8
+
T-cell response in immunized mice after a single application, as detected by MHC multimer staining and gamma interferon (IFN-γ) ELISPOT assay. This CSP-specific response could be significantly enhanced by prime-boost immunization with recombinant ACT in combination with anti-CTLA-4 during the boost immunization. This increased response was accompanied by complete protection in a number of mice after a challenge with
P. berghei
sporozoites. Transient blockade of CTLA-4 may overcome negative regulation and hence provide a strategy to enhance the efficacy of a vaccine by amplifying the number of responding T cells.