bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infection byTrypanosoma cruziMetacyclic Forms Deficient in gp82 but Expressing a Related Surface Molecule, gp30
Authors: Cortez Mauro , Neira Ivan , Ferreira Daniele , Luquetti Alejandro O. , Rassi Anis , Atayde Vanessa D. , Yoshida Nobuko 
Published: October 2003

ABSTRACTTrypanosoma cruzimetacyclic trypomastigotes invade and replicate in the gastric mucosal epithelium after oral infection. In this study we analyzed the process of infection byT. cruziisolates deficient in the expression of gp82, the metacyclic stage-specific surface glycoprotein implicated in target cell entry in vitro and in promoting mucosal infection in mice after oral challenge. Mice infected by the oral route with metacyclic forms of gp82-deficient isolate 569 or 588 developed patent parasitemia but at greatly reduced levels compared to those infected with the gp82-expressing isolate CL. Metacyclic forms of both isolates expressed gp30, a surface glycoprotein detectable by monoclonal antibody (MAb) 3F6 directed to gp82. Otherwise, the gp82-deficient isolates displayed a surface profile similar to that of the CL isolate and also entered epithelial HeLa cells in a manner inhibitable by MAb 3F6 and dependent on the parasite signal transduction that involved the activation of protein tyrosine kinase and Ca2+mobilization from thapsigargin-sensitive stores. Like gp82, gp30 triggered the host cell Ca2+response required for parasite internalization. Purified gp30 and the recombinant gp82 inhibited HeLa cell invasion of metacyclic forms of isolates 569 and 588 by ∼90 and ∼70%, respectively. A cell invasion assay performed in the presence of gastric mucin, mimicking the in vivo infection, showed an inhibition of 70 to 75% in the internalization of gp82-deficient isolates but not of the CL isolate. The recombinant gp82 exhibited an adhesive capacity toward gastric mucin much higher than that of gp30. Taken together, our findings indicate that target cell entry of metacyclic trypomastigotes can be mediated either by gp82 or gp30 but that efficient mucosal infection depends on the expression of gp82.
Comparison of Two Major Forms of the
Shigella
Virulence Plasmid pINV: Positive Selection Is a Major Force Driving the Divergence
Authors: Lan Ruiting , Stevenson Gordon , Reeves Peter R. 
Published: October 2003

ABSTRACT

All
Shigella
and enteroinvasive
Escherichia coli
(EIEC) strains carry a 230-kb virulence plasmid (pINV) which is essential for their invasiveness. There are two sequence forms, pINV A and pINV B, of the plasmid (R. Lan, B. Lumb, D. Ryan, and P. R. Reeves, Infect. Immun. 69:6303-6309, 2001), and the recently sequenced pINV plasmid from
Shigella flexneri
serotype 5 is a pINV B form. In this study we sequenced the majority of the coding region of the pINV A form from
S
.
flexneri
serotype 6 other than insertion sequence or related sequences and compared it with the pINV B form. More than half of the genes sequenced appear to be under positive selection based on their low ratio of synonymous to nonsynonymous substitutions. This high proportion of selected differences indicates that the two pINV forms have functional differences, and comparative studies of pathogenicity in different
Shigella
-EIEC strains could be informative. There are also genes absent in the
S
.
flexneri
serotype 6 plasmid, including the
sepA
gene encoding serine protease, the major secreted protein of
S
.
flexneri
serotype 2a, and the
stbAB
genes, which encode one of the two partition systems found in
S
.
flexneri
serotype 5. The incompatibility of the two pINV forms appears to be due to either small differences in the
mvpAT
postsegregational killing system or the presence of an unknown system in pINVA.
Plasma Interleukin-12 in Malaria-Tolerant Papua New Guineans: Inverse Correlation withPlasmodium falciparumParasitemia and Peripheral Blood Mononuclear Cell Nitric Oxide Synthase Activity
Authors: Boutlis Craig S. , Lagog Moses , Chaisavaneeyakorn Sujittra , Misukonis Mary A. , Bockarie Moses J. , Mgone Charles S. , Wang Zhiqiang , Morahan Grant , Weinberg J. Brice , Udhayakumar Venkatachalam , Anstey Nicholas M. 
Published: October 2003

ABSTRACTInterleukin-12 (IL-12) has been inversely associated with disease severity in human and murine malaria, and a polymorphism in the IL-12 p40 subunit gene (IL12B) has been associated with susceptibility to human cerebral malaria and reduced nitric oxide (NO) production. To better define the relationships between IL-12, NO, malaria parasitemia, andIL12Bpolymorphisms during malarial tolerance, plasma IL-12 levels and peripheral blood mononuclear cell NO synthase (NOS) activity were measured in asymptomatic Papua New Guineans exposed to intense malaria transmission. The IL-12 level was strongly inversely correlated with the density ofPlasmodium falciparumparasitemia (ρ = −0.45;P< 0.001) and was predicted to decrease by 19% (95% confidence interval [CI], 10 to 27%) for each twofold increase inP. falciparumparasitemia. This is consistent with a suppressive effect of parasitemia on IL-12 production, an effect previously shown in vitro and in rodent models of disease. The IL-12 level was inversely correlated with NOS activity (r= −0.22;P= 0.007), with each twofold increase in NOS activity being predictive of a 25% (95% CI, 7 to 38%) decrease in plasma IL-12 levels. This probably reflects additional down-regulation of IL-12 by the high basal NO production and monocyte NOS expression found in the malaria-tolerant state. Neither the IL-12 level nor NOS activity was associated with either of twoIL12Bpolymorphisms, reflecting the diversity of genetic control over immune responses in different populations.
DNA Vaccination Protects Mice against Challenge withListeria monocytogenesExpressing the Hepatitis C Virus NS3 Protein
Authors: Simon Benjamin E. , Cornell Kenneth A. , Clark Tina R. , Chou Sunwen , Rosen Hugo R. , Barry Ronald A. 
Published: October 2003

ABSTRACTThe goal of this study was to develop a new surrogate challenge model for use in evaluating protective cell-mediated immune responses against hepatitis C virus (HCV) antigens. The use of recombinantListeria monocytogenesorganisms which express HCV antigens provides novel tools with which to assay such in vivo protection, as expression of immunity against this hepatotropic bacterial pathogen is dependent on antigen-specific CD8+T lymphocytes. A plasmid DNA vaccine encoding a ubiquitin-NS3 fusion protein was generated, and its efficacy was confirmed by in vivo induction of NS3-specific, gamma interferon-secreting T cells following vaccination of BALB/c mice. These immunized mice also exhibited specific in vivo protection against subsequent challenge with a recombinantL. monocytogenesstrain (TC-LNS3) expressing the NS3 protein. Notably, sublethal infection of naive mice with strain TC-LNS3 induced similar NS3-specific T-cell responses. These findings suggest that recombinant strains ofL. monocytogenesexpressing HCV antigens should prove useful for evaluating, or even inducing, protective immune responses against HCV antigens.
RecombinantLeishmania majorSecreting Biologically Active Granulocyte-Macrophage Colony-Stimulating Factor Survives Poorly in Macrophages In Vitro and Delays Disease Development in Mice
Authors: Dumas Carole , Muyombwe Anthony , Roy Gaétan , Matte Claudine , Ouellette Marc , Olivier Martin , Papadopoulou Barbara 
Published: October 2003

ABSTRACTLeishmaniais an intracellular pathogen that replicates inside macrophages. Activated macrophages produce a specific subset of cytokines that play an important role in the control ofLeishmaniainfections. As part of our interest in developing suicide parasites that produce abortive infections for the purposes of vaccination, we engineered recombinantLeishmania majorstrains producing biologically active granulocyte-macrophage colony-stimulating factor (GM-CSF). We showed that GM-CSF is being produced in the phagosomes of infected macrophages and that it can be detected in the culture supernatants of both infected macrophages and extracellular parasites. Our data support the notion that GM-CSF secreted by both developmental forms of recombinantL. majorcan activate macrophages to produce high levels of proinflammatory cytokines such as interleukin-1β (IL-1β), IL-6, and IL-18 and various chemokines including RANTES/CCL5, MIP-1α/CCL3, MIP-1β/CCL4, MIP-2/CXCL2, and MCP-1/CCL2, which enhance parasite killing. Indeed, GM-CSF-expressing parasites survive poorly in macrophages in vitro and produce delayed lesion development in susceptible BALB/c mice in vivo. Selective killing of intracellularLeishmaniaexpressing cytokine genes capable of activating cellular responses may constitute a promising strategy to control and/or prevent parasitic infections.
Vaccination withToxoplasma gondiiSAG-1 Protein Is Protective against Congenital Toxoplasmosis in BALB/c Mice but Not in CBA/J Mice
Authors: Letscher-Bru Valerie , Pfaff Alexander W. , Abou-Bacar Ahmed , Filisetti Denis , Antoni Elisabeth , Villard Odile , Klein Jean-Paul , Candolfi Ermanno 
Published: October 2003

ABSTRACTWe evaluated the effect of vaccination with the SAG1 protein ofToxoplasma gondiiagainst congenital toxoplasmosis in mice with different genetic backgrounds. In BALB/c mice (H-2d), vaccination reduced the number of infected fetuses by 50% and was associated with a mixed type 1 and type 2 immunity. In CBA/J mice (H-2k), vaccination increased the number of infected fetuses by 50% and was associated with a predominant type 2 response. Our results indicate that the effect of vaccination with SAG1 is controlled by the genetic background of the mouse.
Toll-Like Receptor Expression in C3H/HeN and C3H/HeJ Mice duringSalmonella entericaSerovar Typhimurium Infection
Authors: Tötemeyer Sabine , Foster Neil , Kaiser Pete , Maskell Duncan J. , Bryant Clare E. 
Published: October 2003

ABSTRACTHere, we have investigated the mRNA expression of Toll-like receptor 2 (TLR-2), TLR-4, and MD-2 in spleens and livers of C3H/HeN mice (carrying wild-type TLR-4) and C3H/HeJ mice (carrying mutated TLR-4) in response toSalmonellainfection. DuringSalmonellainfections, TLR-4 is activated, leading to increased TLR-2 and decreased TLR-4 expression.
The MicAB Two-Component Signaling System Is Involved in Virulence of
Streptococcus pneumoniae
Authors: Kadioglu Aras , Echenique Josè , Manco Sonia , Trombe Marie-Claude , Andrew Peter W. 
Published: October 2003

ABSTRACT

In
Streptococcus pneumoniae
, the two-component signaling system MicAB was previously shown to contribute to repression of competence when oxygen is limited. In virulent strains expressing the serotype 2 and 6 capsule, mutation of the MicB kinase reduced the lag period of growth when cultures were switched from an aerobic to anaerobic atmosphere. After intranasal challenge of mice, the
micB
::
km
mutation decreased virulence, as shown by the absence of symptoms and by a lower level of recovery of CFU from lungs and blood. It is proposed that MicAB is involved in the adaptive response of the bacteria to changes in oxygen level during the course of infection.
Putative Interhelical Interactions within the PheP Protein Revealed by Second-Site Suppressor Analysis
Authors: Dogovski C. , Pi J. , Pittard A. J. 
Published: October 2003

ABSTRACT
Highly conserved glycine residues within span I and span II of the phenylalanine and tyrosine transporter PheP were shown to be important for the function of the wild-type protein. Replacement by amino acids with increasing side chain volume led to progressive loss of transport activity. Second-site suppression studies performed with a number of the primary mutants revealed a tight packing arrangement between spans I and II that is important for function and an additional interaction between spans I and III. We also postulate that a third motif, GXXIG, present in span I and highly conserved within different members of the amino acid-polyamine-organocation family, may function as a dimerization motif. Surprisingly, other highly conserved residues, such as Y60 and L41, could be replaced by various residues with no apparent loss of activity.
Involvement of an Inducible Fructose Phosphotransferase Operon in
Streptococcus gordonii
Biofilm Formation
Authors: Loo C. Y. , Mitrakul K. , Voss I. B. , Hughes C. V. , Ganeshkumar N. 
Published: October 2003

ABSTRACT

Oral streptococci, such as
Streptococcus gordonii
, are the predominant early colonizers that initiate biofilm formation on tooth surfaces. Investigation of an
S. gordonii
::Tn
917-lac
biofilm-defective mutant isolated by using an in vitro biofilm formation assay showed that the transposon insertion is near the 3′ end of an open reading frame (ORF) encoding a protein homologous to
Streptococcus mutans
FruK. Three genes,
fruR
,
fruK
, and
fruI
, were predicted to encode polypeptides that are part of the fructose phosphotransferase system (PTS) in
S. gordonii
. These proteins, FruR, FruK, and FruI, are homologous to proteins encoded by the inducible
fruRKI
operon of
S. mutans
. In
S. mutans
, FruR is a transcriptional repressor, FruK is a fructose-1-phosphate kinase, and FruI is the fructose-specific enzyme II (fructose permease) of the phosphoenolpyruvate-dependent sugar PTS. Reverse transcription-PCR confirmed that
fruR
,
fruK
, and
fruI
are cotranscribed as an operon in
S. gordonii
, and the transposon insertion in
S. gordonii fruK
::Tn
917-lac
resulted in a nonpolar mutation. Nonpolar inactivation of either
fruK
or
fruI
generated by allelic replacement resulted in a biofilm-defective phenotype, whereas a nonpolar mutant with an inactivated
fruR
gene retained the ability to form a biofilm. Expression of
fruK
, as measured by the β-galactosidase activity of the
fruK
::Tn
917-lac
mutant, was observed to be growth phase dependent and was enhanced when the mutant was grown in media with high levels of fructose, sucrose, xylitol, and human serum, indicating that the fructose PTS operon was fructose and xylitol inducible, similar to the
S. mutans
fructose PTS. The induction by fructose was inhibited by the presence of glucose, indicating that glucose is able to catabolite repress
fruK
expression. Nonpolar inactivation of the
fruR
gene in the
fruK
::Tn
917-lac
mutant resulted in a greater increase in β-galactosidase activity when the organism was grown in media supplemented with fructose, confirming that
fruR
is a transcriptional repressor of the fructose PTS operon. These results suggest that the regulation of fructose transport and metabolism in
S. gordonii
is intricately tied to carbon catabolite control and the ability to form biofilms. Carbon catabolite control, which modulates carbon flux in response to environmental nutritional levels, appears to be important in the regulation of bacterial biofilms.
The IS
1111
Family Members IS
4321
and IS
5075
Have Subterminal Inverted Repeats and Target the Terminal Inverted Repeats of Tn
21
Family Transposons
Authors: Partridge Sally R. , Hall Ruth M. 
Published: October 2003

ABSTRACT

IS
5075
and IS
4321
are closely related (93.1% identical) members of the IS
1111
family that target a specific position in the 38-bp terminal inverted repeats of Tn
21
family transposons and that are inserted in only one orientation. They are 1,327 bp long and have identical ends consisting of short inverted repeats of 12 bp with an additional 7 bp (TAATGAG) or 6 bp (AATGAG) to the left of the left inverted repeats and 3 bp (AGA) or 4 bp (AGAT) to the right of the right inverted repeat. Circular forms of IS
5075
and IS
4321
in which the inverted repeats are separated by abutting terminal sequences (AGATAATGAG) were detected. A similar circular product was found for the related ISPa11. Transposition of IS
4321
into the 38-bp target site was detected, but a flanking duplication was not generated. The precisely reconstituted target site was also identified. Over 50 members of the IS
1111
family were identified. They encode related transposases, have related inverted repeats, and include related bases that lie outside these inverted repeats. In some, the flanking bases number 5 or 6 on the left and 4 or 3 on the right. Specific target sites were found for several of these insertion sequence (IS) elements. IS
1111
family members therefore differ from the majority of IS elements, which are characterized by terminal inverted repeats and a target site duplication, and from members of the related IS
110
family, which do not have obvious inverted repeats near their termini.
Cohabitation with a Sick Cage Mate: Consequences on Behavior and on Ehrlich Tumor Growth
Authors: Morgulis Maria Sílvia F.A. , Stankevicius Daniel , Sá-Rocha Luiz Carlos , Palermo-Neto João 
Published: October 2003

The present study analyzed the effects of cohabitation for 11 days with a sick cage mate on behavior and Ehrlich tumor growth in mice. Pairs of female mice were divided into one control and one experimental group. One mouse of each control pair was kept undisturbed and called ‘healthy companion’ (HC). One animal of each experimental pair of mice was inoculated (i.p.) with 5 × 10<sup>6</sup> Ehrlich tumor cells, and the other, the object of this study, was called ‘sick companion’ (SC). The SC mice presented: (1) increased activity in an open field, (2) increased number of entries and of movements within the plus-maze open arms, (3) similar levels of plus-maze closed-arm exploration, (4) a decrease in the exploratory activity in a hole board, (5) a decrease in the number of white but not red blood cells, and (6) similar corticosterone serum levels. Eleven days after cohabitation with a conspecific, HC and SC mice were injected with 5 ×10<sup>6</sup> Ehrlich tumor cells. Results showed that SC animals presented decreased resistance to the ascitic form of the Ehrlich tumor. The observed data provide experimental evidence that psychosocial stress induced by cohabitation with a sick cage mate changed at the same time some behavioral and physiological parameters, and decreased resistance to Ehrlich tumor. These data are discussed in the light of a possible neuroimmune system interaction.
fMRI Evidence for Cortical Modification during Learning of Mandarin Lexical Tone
Authors: Wang Yue , Sereno Joan A. , Jongman Allard , Hirsch Joy 
Published: October 2003

Abstract
Functional magnetic resonance imaging was employed before and after six native English speakers completed lexical tone training as part of a program to learn Mandarin as a second language. Language-related areas including Broca's area, Wernicke's area, auditory cortex, and supplementary motor regions were active in all subjects before and after training and did not vary in average location. Across all subjects, improvements in performance were associated with an increase in the spatial extent of activation in left superior temporal gyrus (Brodmann's area 22, putative Wernicke's area), the emergence of activity in adjacent Brodmann's area 42, and the emergence of activity in right inferior frontal gyrus (Brodmann's area 44), a homologue of putative Broca's area. These findings demonstrate a form of enrichment plasticity in which the early cortical effects of learning a tone-based second language involve both expansion of preexisting language-related areas and recruitment of additional cortical regions specialized for functions similar to the new language functions.
An Industrial Process for Adipic Acid Production by the Liquid-Phase Oxidation of Cyclohexanone with Molecular Oxygen
Authors: Shimizu Atsushi , Tanaka Katsutoshi , Ogawa Hiroo , Matsuoka Yuji , Fujimori Masami , Nagamori Yukito , Hamachi Hidefumi , Kimura Kazuyoshi 
Published: October 2003

Abstract
Adipic acid is produced industrially by the oxidation of cyclohexanone and cyclohexanol with nitric acid. Dinitrogen oxide (nitrous oxide, N2O), a non-CO2 greenhouse gas, is produced as a by-product in this process. We have investigated an industrial process for the production of adipic acid without the generation of N2O. When acetic acid was used as a solvent and Mn(OAc)2/Co(OAc)2 were used as catalysts under atmospheric pressure of pure O2 at 70 °C, the selectivity of adipic acid was 77% and the combined selectivity of carboxylic acids, which consisted of adipic acid, glutaric acid, and succinic acid, was 93% for the 100% conversion of cyclohexanone. We presume that adipic acid is generated via 6-oxohexanoic acid. Glutaric acid was probably generated via 5-oxopentanoic acid in the reaction path that branched at 6-oxohexanoic acid. When air containing less than 10 vol % of oxygen was used at 1.22 MPa in order to avoid explosion hazards, the selectivity of adipic acid was 78% for a 99.3% conversion of cyclohexanone. We conclude that the present reaction can be used as an industrial process for adipic acid production.
Management of Anemia in Erythropoietin-Resistant Hemodialysis Patients
Authors: Santos Anne E Dar , Shalansky Karen F , Jastrzebski Jacek P 
Published: October 2003

BACKGROUND: Human recombinant erythropoietin (rHuEPO) is administered to patients with end-stage renal disease for treatment of anemia. OBJECTIVE: To assess the impact of a structured team approach to anemia management in rHuEPO-resistant hemodialysis patients. METHODS: This was an 8-month prospective, open-label, quality-improvement initiative. Nineteen patients in a 160-bed hemodialysis unit receiving rHuEPO doses >300 units/kg/wk were defined as rHuEPO-resistant. Hemoglobin (Hb), iron indices, parathyroid hormone, folate, B12, aluminum, and reticulocyte counts were determined at baseline. The former 3 parameters were followed every 6, 12, and 26 weeks, respectively. Vascular access flow was regularly assessed via ultrasonic dilution methodology. Target Hb was 12.0–13.5 g/dL. All factors potentially contributing to rHuEPO resistance were assessed and, if possible, treated every 6 weeks by a dedicated anemia team. Downward rHuEPO dosage adjustments of 12.5–25% to the closest 1000 units were considered if underlying causes of rHuEPO resistance could not be identified or reversed, or if the Hb rose beyond the target level. RESULTS: Dysfunctional vascular access and iron deficiency were the predominant treatable factors associated with rHuEPO resistance. At 8 months, mean rHuEPO dosage decreased significantly from 469 to 319 units/kg/wk (p < 0.001) and mean Hb increased significantly from 10.6 to 11.6 g/dL (p = 0.023). Eight-month cost savings approximated $45 000 (CDN$). CONCLUSIONS: A structured team approach to the management of rHuEPO-resistant patients was successful in significantly lowering rHuEPO dosage with improvement in serum Hb at a substantial cost savings.
Stability of Cyclophosphamide and Mesna Admixtures in Polyethylene Infusion Bags
Authors: Menard Cedric , Bourguignon Celine , Schlatter Joël , Vermerie Norbert 
Published: October 2003

BACKGROUND: Cyclophosphamide (CYP) is used to treat cancers in combination with mesna to prevent cystitis. The use of extemporaneously prepared admixtures of these drugs must be supported by documentation of their chemical stability. OBJECTIVE: To evaluate the chemical stability of CYP and mesna admixtures in dextrose 5% polyethylene infusion bags. METHODS: The drugs were diluted in 100-mL dextrose 5% infusion bags to final concentrations of CYP 10.8 mg/mL with mesna 3.2 mg/mL (solution A) and CYP 1.8 mg/mL with mesna 0.54 mg/mL (solution B). Six infusion bags from each solution were stored at 4 °C and 6 were stored at room temperature. Triplicate HPLC determinations were performed on each bag to measure drug concentrations at 0, 1, 2, 4, 6, 12, 24, 48, and 96 hours. RESULTS: At 96 hours, drug concentrations in all solutions stored at room temperature were found to be <80% compared with the initial concentrations. The solutions stored at 4 °C retained at least 90% of the initial drug concentrations at 48 hours. The pH of solutions A and B stored at room temperature decreased significantly by 4.44 and 4.31 units, respectively. The pH of the refrigerated infusion bags decreased significantly by 1.46 units for solution B. CONCLUSIONS: Admixtures stored at 4 °C (pH 7.90 ± 0.004; mean ± SD) are stable for 48 hours. The CYP and mesna combination can be infused at room temperature over 6 hours without significant degradation of the drugs. Stabilities are dependent on pH, temperature, and/or concentration.