bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contribution of
Lactococcus lactis
Cell Envelope Proteinase Specificity to Peptide Accumulation and Bitterness in Reduced-Fat Cheddar Cheese
Authors: Broadbent Jeffery R. , Barnes Mary , Brennand Charlotte , Strickland Marie , Houck Kristen , Johnson Mark E. , Steele James L. 
Published: July 2002

ABSTRACT

Bitterness is a flavor defect in Cheddar cheese that limits consumer acceptance, and specificity of the
Lactococcus lactis
extracellular proteinase (lactocepin) is widely believed to be a key factor in the development of bitter cheese. To better define the contribution of this enzyme to bitterness, we investigated peptide accumulation and bitterness in 50% reduced-fat Cheddar cheese manufactured with single isogenic strains of
Lactococcus lactis
as the only starter. Four isogens were developed for the study; one was lactocepin negative, and the others produced a lactocepin with group a, e, or h specificity. Analysis of cheese aqueous extracts by reversed-phase high-pressure liquid chromatography confirmed that accumulation of α
S1
-casein (f 1-23)-derived peptides f 1-9, f 1-13, f 1-16, and f 1-17 in cheese was directly influenced by lactocepin specificity. Trained sensory panelists demonstrated that Cheddar cheese made with isogenic starters that produced group a, e, or h lactocepin was significantly more bitter than cheese made with a proteinase-negative isogen and that propensity for bitterness was highest in cells that produced group h lactocepin. These results confirm the role of starter proteinase in bitterness and suggest that the propensity of some industrial strains for production of the bitter flavor defect in cheese could be altered by proteinase gene exchange or gene replacement.
Abnormal CD40 Ligand (CD154) Expression in Human Immunodeficiency Virus-Infected Children
Authors: O'Gorman Maurice R. G. , DuChateau Brian , Paniagua Mary , Hunt Janelle , Bensen Nicolas , Yogev Ram 
Published: July 2002

ABSTRACTThe CD40 ligand (CD154), expressed primarily on activated CD4-positive T cells, is a costimulatory molecule involved in B-cell proliferation, germinal center formation, and immunoglobulin class switching. Since B-cell abnormalities including hypergammaglobulinemia and abnormal antibody-specific immune responses are prominent and occur early during the course of pediatric human immunodeficiency virus (HIV) infection, we measured the baseline levels and the induced levels of expression of CD154 on CD3+CD8−(T helper cells) in HIV-infected children and uninfected children born to HIV-positive mothers. The percentage of CD154+T helper cells activated in vitro and the level of CD154 expressed per T helper cell (mean fluorescent channel [MFC]) were significantly lower in the HIV-infected children than in the uninfected control group (77% ± 3% versus 89% ± 1%, respectively [P< 0.002], and 261 ± 174 versus 415 ± 130 MFC, respectively [P< 0.03]). The levels of CD154 expressed on resting T helper cells in the HIV-infected group were not significantly different from the levels observed in the control group. In the HIV-infected children, the level of CD154 on activated T helper cells correlated with the level of immunodeficiency, as assessed by the CD4 T-cell levels (correlation coefficient [r] = 0.707,P= 0.003), but did not correlate with the viral load or with any of the serum immunoglobulin concentrations measured in this group of HIV-infected children. The baseline level of CD154 expressed on T helper cells did, however, correlate with the concentration of immunoglobulin A in serum. We conclude that HIV-infected children have impaired regulation of CD154 expression which may contribute to the immune dysregulation commonly observed.
Receiver Operating Characteristics Analyses of Food and Drug Administration-Cleared Serological Assays for Natural Rubber Latex-Specific Immunoglobulin E Antibody
Authors: Biagini Raymond E. , Krieg Edward F. , Pinkerton Lynne E. , Hamilton Robert G. 
Published: July 2002

ABSTRACT

Receiver operating characteristics (ROC) analyses to evaluate and compare the diagnostic accuracy of Food and Drug Administration (510K)-cleared natural rubber latex (NRL)-specific immunoglobulin E (IgE) antibody immunoassays have not been performed using well-characterized skin-testing reagents. Sera were collected from 311 subjects (131 latex puncture skin test [PST] positive and 180 PST negative). All masked, coded sera were analyzed for latex-specific IgE antibodies in the Diagnostic Products Corporation microplate AlaSTAT, HYCOR HY-TEC RAST, and Pharmacia-Upjohn CAP System RAST FEIA (CAP). Diagnostic accuracy was evaluated using GraphRoc for Windows software to construct and analyze ROC curves in relation to the subjects' PST status and the results of the immunoassays. The ROC areas under the curve (AUCs) ± standard error based on PST for the three diagnostic tests were 0.858 ± 0.024, 0.869 ± 0.024, and 0.924 ± 0.017, respectively, for AlaSTAT, CAP, and HY-TEC. The HY-TEC system had a significantly greater AUC based on PST than those observed for AlaSTAT (
P
< 0.05) and CAP (
P
< 0.05) analyses. When the diagnostic tests were probed as to the cutoffs giving maximal diagnostic efficiency compared to PST, CAP and AlaSTAT yielded values of <0.35 kU of allergen IgE (kU
A
)/liter and <0.35 kU/liter while the HY-TEC assay yielded 0.11 kU/liter. The diagnostic efficiencies based on PST in our cohort at these cutoffs were 87.1, 88.1, and 88.7%, respectively. The HY-TEC assay had a significantly greater AUC than CAP and AlaSTAT using PST as a diagnostic discriminator in our cohort. When the HY-TEC system was probed at its maximally efficient cutoff (0.11 kU/liter) versus HYCOR's recommended cutoff of 0.05 kU/liter, a loss of sensitivity of 8.4% was observed with a gain in specificity of 19.5%.
Infection with the HelminthNippostrongylus brasiliensisDoes Not Interfere with Efficient Elimination ofMycobacterium bovisBCG from the Lungs of Mice
Authors: Erb Klaus J. , Trujillo Claudia , Fugate Mike , Moll Heidrun 
Published: July 2002

ABSTRACTInfection withMycobacterium tuberculosiscontinues to be one of the major global health threats. Strong mycobacterium-specific Th1 immune responses correlate with protection, and decreased Th1 responses correlate with disease progression. In contrast, the impact of Th2 responses on the development of protective immune responses to mycobacteria remains unclear. To analyze whether ongoing Th2 responses present in the lung influence the development of a protective Th1 immune response to mycobacteria, we coinfected mice with the helminthNippostrongylus brasiliensisandMycobacterium bovisBCG. We found that the T cells from the lymph nodes of coinfected mice secreted significantly less gamma interferon than did the T cells from mice infected withM. bovisBCG after in vitro stimulation with purified protein fromM. tuberculosiswhen 108CFU ofM. bovisBCG were used for the infection. This result indicates that the helminth infection reduced the Th1 immune response to the mycobacteria in the lung. However, mycobacterial clearance was not delayed in the coinfected animals. Importantly, the infection with BCG after the helminth infection did not reduce the helminth-induced Th2 response in the lung, ruling out the possibility that the lack of a reduction in bacterial clearance in the coinfected mice was due to a downmodulation of the helminth-induced Th2 response. Taken together, our results suggest that ongoing Th2 responses in the lung do not necessarily lead to increased susceptibility to mycobacterial infection.
Sex-Associated Hormones and Immunity to Protozoan Parasites
Authors: Roberts Craig W. , Walker William , Alexander James 
Published: July 2002

SUMMARYNumerous epidemiological and clinical studies have noted differences in the incidence and severity of parasitic diseases between males and females. Although in some instances this may be due to gender-associated differences in behavior, there is overwhelming evidence that sex-associated hormones can also modulate immune responses and consequently directly influence the outcome of parasitic infection. Animal models of disease can often recreate the gender-dependent differences observed in humans, and the role of sex-associated hormones can be confirmed by experimentally altering their levels. Under normal circumstances, levels of sex hormones not only differ between males and females but vary according to age. Furthermore, not only are females of reproductive age subject to the regular hormonal cycles which control ovulation, they are also exposed to dramatically altered levels during pregnancy. It is thus not surprising that the severity of many diseases, including those caused by parasites, has been shown to be affected by one or more of these circumstances. In addition, infection with many pathogens has been shown to have an adverse influence on pregnancy. In this article we review the impact of sex-associated hormones on the immune system and the development and maintenance of immunity to the intracellular protozoan parasites Toxoplasma gondii, Plasmodium spp., and Leishmania spp.
Molecular Machinations: Chemokine Signals in Host-Pathogen Interactions
Authors: Chensue Stephen W. 
Published: July 2002

SUMMARYChemokines and their G-protein-coupled receptors represent an ancient and complex system of cellular communication participating in growth, development, homeostasis and immunity. Chemokine production has been detected in virtually every microbial infection examined; however, the precise role of chemokines is still far from clear. In most cases they appear to promote host resistance by mobilizing leukocytes and activating immune functions that kill, expel, or sequester pathogens. In other cases, the chemokine system has been pirated by pathogens, especially protozoa and viruses, which have exploited host chemokine receptors as modes of cellular invasion or developed chemokine mimics and binding proteins that act as antagonists or inappropriate agonists. Understanding microbial mechanisms of chemokine evasion will potentially lead to novel antimicrobial and anti-inflammatory therapeutic agents.
Rapid Diagnostic Tests for Malaria Parasites
Authors: Moody Anthony 
Published: July 2002

SUMMARY
Malaria presents a diagnostic challenge to laboratories in most countries. Endemic malaria, population movements, and travelers all contribute to presenting the laboratory with diagnostic problems for which it may have little expertise available. Drug resistance and genetic variation has altered many accepted morphological appearances of malaria species, and new technology has given an opportunity to review available procedures. Concurrently the World Health Organization has opened a dialogue with scientists, clinicians, and manufacturers on the realistic possibilities for developing accurate, sensitive, and cost-effective rapid diagnostic tests for malaria, capable of detecting 100 parasites/μl from all species and with a semiquantitative measurement for monitoring successful drug treatment. New technology has to be compared with an accepted Rgold standardS that makes comparisons of sensitivity and specificity between different methods. The majority of malaria is found in countries where cost-effectiveness is an important factor and ease of performance and training is a major consideration. Most new technology for malaria diagnosis incorporates immunochromatographic capture procedures, with conjugated monoclonal antibodies providing the indicator of infection. Preferred targeted antigens are those which are abundant in all asexual and sexual stages of the parasite and are currently centered on detection of HRP-2 from Plasmodium falciparum and parasite-specific lactate dehydrogenase or Plasmodium aldolase from the parasite glycolytic pathway found in all species. Clinical studies allow effective comparisons between different formats, and the reality of nonmicroscopic diagnoses of malaria is considered.
Effects of Interleukin-4 Deprivation and Treatment on Resistance toTrypanosoma cruzi
Authors: Abrahamsohn Ises A. , da Silva Ana Paula Galvão , Coffman Robert L. 
Published: July 2002

ABSTRACTTrypanosoma cruzi(Y strain)-infected interleukin-4−/−(IL-4−/−) mice of strains 129/J, BALB/c, and C57BL/6 showed no significant difference in parasitemia levels or end point mortality rates compared to wild-type (WT) mice. Higher production of gamma interferon (IFN-γ) by parasite antigen (Ag)-stimulated splenocytes was observed only for C57BL/6 IL-4−/−mice. Treatment of 129/J WT mice with recombinant IL-4 (rIL-4), rIL-10, anti-IL-4, and/or anti-IL-10 monoclonal antibodies (MAbs) did not modify parasitism. However, WT mice treated with rIL-4 and rIL-10 had markedly increased parasitism and suppressed IFN-γ synthesis by spleen cells stimulated with parasite Ag, concanavalin A, or anti-CD3. Addition of anti-IL-4 MAbs to splenocyte cultures from infected WT 129/J, BALB/c, or C57BL/6 mice failed to modify IFN-γ synthesis levels; in contrast, IL-10 neutralization increased IFN-γ production and addition of rIL-4 and/or rIL-10 diminished IFN-γ synthesis. We conclude that endogenous IL-4 is not a major determinant of susceptibility to Y strainT. cruziinfection but that IL-4 can, in association with IL-10, modulate IFN-γ production and resistance.
Characterization of Heat-Inducible Expression and Cloning of HtpG (Hsp90 Homologue) of
Porphyromonas gingivalis
Authors: Lopatin Dennis E. , Combs Allison , Sweier Domenica G. , Fenno J. Christopher , Dhamija Sangeeta 
Published: July 2002

ABSTRACT

Porphyromonas gingivalis
is implicated in the etiology of periodontal disease. Associations between microbial virulence and stress protein expression have been identified in other infections. For example, Hsp90 homologues in several microbial species have been shown to contribute to virulence. We previously reported that
P. gingivalis
possessed an Hsp90 homologue (HtpG) which cross-reacts with human Hsp90. In addition, we found that elevated levels of serum antibody to Hsp90 stress protein in individuals colonized with this microorganism were associated with periodontal health. However, the role of HtpG in
P. gingivalis
has not been explored. Therefore, we cloned the
htpG
gene and investigated the characteristics of HtpG localization and expression in
P. gingivalis. htpG
exists as a single gene of 2,052 bp from which a single message encoding a mature protein of approximately 68 kDa is transcribed. Western blot analysis revealed that the 68-kDa polypeptide was stress inducible and that a major band at 44 kDa and a minor band at 40 kDa were present at constitutive levels. Cellular localization studies revealed that the 44- and 40-kDa species were associated with membrane and vesicle fractions, while the 68-kDa polypeptide was localized to the cytosolic fractions.
Nitric Oxide Participation in the Fungicidal Mechanism of Gamma Interferon-Activated Murine Macrophages againstParacoccidioides brasiliensisConidia
Authors: Gonzalez Angel , de Gregori Waldemar , Velez Diana , Restrepo Angela , Cano Luz E. 
Published: July 2002

ABSTRACTParacoccidioidomycosis, a systemic mycosis restricted to Latin America and produced by the dimorphic fungusParacoccidioides brasiliensis, is probably acquired by inhalation of conidia produced by the mycelial form. The macrophage (Mφ) represents the major cell defense against this pathogen; when activated with gamma interferon (IFN-γ), murine Mφs kill the fungus by an oxygen-independent mechanism. Our goal was to determine the role of nitric oxide in the fungicidal effect of Mφs onP. brasiliensisconidia. The results revealed that IFN-γ-activated murine Mφs inhibited the conidium-to-yeast transformation process in a dose-dependent manner; maximal inhibition was observed in Mφs activated with 50 U/ml and incubated for 96 h at 37°C. When Mφs were activated with 150 to 200 U of cytokine per ml, the number of CFU was 70% lower than in nonactivated controls, indicating that there was a fungicidal effect. The inhibitory effect was reversed by the addition of anti-IFN-γ monoclonal antibodies. Activation by IFN-γ also enhanced Mφ nitric oxide production, as revealed by increasing NO2values (8 ± 3 μM in nonactivated Mφs versus 43 ± 13 μM in activated Mφs). The neutralization of IFN-γ also reversed nitric oxide production at basal levels (8 ± 5 μM). Additionally, we found that there was a significant inverse correlation (r= −0.8975) between NO2−concentration and transformation ofP. brasiliensisconidia. Additionally, treatment with any of the three different nitric oxide inhibitors used (arginase,NG-monomethyl-l-arginine, and aminoguanidine), reverted the inhibition of the transformation process with 40 to 70% of intracellular yeast and significantly reduced nitric oxide production. These results show that IFN-γ-activated murine Mφs killP. brasiliensisconidia through thel-arginine–nitric oxide pathway.
Characterization and Formulation of Multiple Epitope-Specific Neutralizing Monoclonal Antibodies for Passive Immunization against Cryptosporidiosis
Authors: Schaefer Deborah A. , Auerbach-Dixon Beth A. , Riggs Michael W. 
Published: July 2002

ABSTRACTThe coccidian parasiteCryptosporidium parvumcauses diarrhea in humans, calves, and other mammals. Neither immunization nor parasite-specific pharmaceuticals that are consistently effective against this organism are available. While polyclonal antibodies against wholeC. parvumreduce infection, their efficacy and predictability are suboptimal. We hypothesized that passive immunization against cryptosporidiosis could be improved by using neutralizing monoclonal antibodies (MAbs) targeting functionally defined antigens on the infective stages. We previously reported that the apical complex and surface-exposed zoite antigens CSL, GP25-200, and P23 are critical in the infection process and are therefore rational targets. In the present study, a panel of 126 MAbs generated against affinity-purified CSL, GP25-200, and P23 was characterized to identify the most efficacious neutralizing MAb formulation targeting each antigen. To identify neutralizing MAbs, sporozoite infectivity following exposure to individual MAbs was assessed by enzyme-linked immunosorbent assay. Of 126 MAbs evaluated, 47 had neutralizing activity. These were then evaluated individually in oocyst-challenged neonatal mice, and 14 MAbs having highly significant efficacy were identified for further testing in formulations. Epitope specificity assays were performed to determine if candidate MAbs recognized the same or different epitopes. Formulations of two or three neutralizing MAbs, each recognizing distinct epitopes, were then evaluated. A formulation of MAbs 3E2 (anti-CSL [αCSL]), 3H2 (αGP25-200), and 1E10 (αP23) provided highly significant additive efficacy over that of either individual MAbs or combinations of two MAbs and reduced intestinal infection by 86 to 93%. These findings indicate that polyvalent neutralizing MAb formulations targeting epitopes on defined antigens may provide optimal passive immunization against cryptosporidiosis.
Classical and El Tor Biotypes of
Vibrio cholerae
Differ in Timing of Transcription of
tcpPH
during Growth in Inducing Conditions
Authors: Murley Yvette M. , Behari Jaideep , Griffin Robert , Calderwood Stephen B. 
Published: July 2002

ABSTRACT

Two protein pairs in
Vibrio cholerae
, ToxRS and TcpPH, are necessary for transcription from the
toxT
promoter and subsequent expression of cholera virulence genes. We have previously shown that transcription of
tcpPH
in classical strains of
V. cholerae
is activated at mid-log-phase growth in ToxR-inducing conditions, while transcription of
tcpPH
in El Tor strains is not. In this study, we showed that while transcription of
tcpPH
differs at mid-log-phase growth in ToxR-inducing conditions between the biotypes, transcription is equivalently high during growth in AKI conditions. We used
tcpPH
::
gusA
transcriptional fusions to quantitate expression of
tcpPH
in each biotype throughout growth in ToxR-inducing conditions and showed that although transcription of
tcpPH
is reduced at mid-log-phase growth in an El Tor strain, transcription is turned on later in growth to levels in excess of those in the classical strain (although cholera toxin is not produced). This suggests that the difference in expression of cholera virulence factors in response to ToxR-inducing conditions between the El Tor and classical biotypes of
V. cholerae
may be related to the timing of transcription of
tcpPH
rather than the absolute levels of transcription.
Inhibitory and Bactericidal Effects of Hydrogen Peroxide Production byStreptococcus pneumoniaeon Other Inhabitants of the Upper Respiratory Tract
Authors: Pericone Christopher D. , Overweg Karin , Hermans Peter W. M. , Weiser Jeffrey N. 
Published: July 2002

ABSTRACTAn inverse correlation between colonization of the human nasopharynx byStreptococcus pneumoniaeandHaemophilus influenzae, both common upper respiratory pathogens, has been reported. Studies were undertaken to determine if either of these organisms produces substances which inhibit growth of the other. Culture supernatants fromS. pneumoniaeinhibited growth ofH. influenzae, whereas culture supernatants fromH. influenzaehad no effect on the growth ofS. pneumoniae. Moreover, coculture ofS. pneumoniaeandH. influenzaeled to a rapid decrease in viable counts ofH. influenzae. The addition of purified catalase prevented killing ofH. influenzaein coculture experiments, suggesting that hydrogen peroxide may be responsible for this bactericidal activity.H. influenzaewas killed by concentrations of hydrogen peroxide similar to that produced byS. pneumoniae. Hydrogen peroxide is produced by the pneumococcus through the action of pyruvate oxidase (SpxB) under conditions of aerobic growth. Both anspxBmutant and a naturally occurring variant ofS. pneumoniae, which is downregulated in SpxB expression, were unable to killH. influenzae. A catalase-reversible inhibitory effect ofS. pneumoniaeon the growth of the respiratory tract pathogensMoraxella catarrhalisandNeisseria meningitidiswas also observed. Elevated hydrogen peroxide production, therefore, may be a means by whichS. pneumoniaeis able to inhibit a variety of competing organisms in the aerobic environment of the upper respiratory tract.
Aromatic Compound-Dependent
Brucella suis
Is Attenuated in Both Cultured Cells and Mouse Models
Authors: Foulongne Vincent , Walravens Karl , Bourg Giséle , Boschiroli Maria Laura , Godfroid Jacques , Ramuz Michel , O'Callaghan David 
Published: July 2002

ABSTRACT

The
aroC
gene of the facultative intracellular pathogen
Brucella suis
was cloned and sequenced. The cloned
aroC
gene complements
Escherichia coli
and
Salmonella enterica
serovar Typhimurium
aroC
mutants. A
B. suis aroC
mutant was found to be unable to grow in a defined medium without aromatic compounds. The mutant was highly attenuated in tissue culture (THP1 macrophages and HeLa cells) and murine virulence models.