bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vitro Adhesion and Platelet Aggregation Properties of Bacteremia-Associated Lactobacilli
Authors: Kirjavainen Pirkka V. , Tuomola Elina M. , Crittenden Ross G. , Ouwehand Arthur C. , Harty Derek W. S. , Morris Leone F. , Rautelin Hilpi , Playne Martin J. , Donohue Diana C. , Salminen Seppo J. 
Published: December 2019

ABSTRACT

Eight bacteremia-associated
Lactobacillus
strains were evaluated in vitro for the ability to adhere to human intestinal mucosa and to aggregate platelets. Adherence varied significantly among the strains, and platelet aggregation was induced by three strains. In conclusion, strong binding ability does not appear to be a prerequisite for the involvement of lactobacilli in bacteremia or to their ability to aggregate platelets.
Deficiency in Tumor Necrosis Factor Alpha Activity Does Not Impair Early Protective Th1 Responses against Blood-Stage Malaria
Authors: Sam Hakeem , Su Zhong , Stevenson Mary M. 
Published: December 2019

ABSTRACTBlood-stagePlasmodium chabaudiAS infection was controlled by 4 weeks in mice with deletion of tumor necrosis factor p55 and p75 receptors (TNFR-knockout [KO]) and control wild-type (WT) mice, although female TNFR-KO mice showed slightly but significantly higher parasitemia immediately following the peak. Serum interleukin 12 (IL-12) p70 and gamma interferon (IFN-γ) levels were similar but tumor necrosis factor alpha levels were significantly higher in TNFR-KO mice than in WT controls. Splenic IL-12 receptor β1 and β2 and IFN-γ mRNA expression, as well as spleen cell production of IFN-γ and IL-4, were comparable in both mouse types, but IL-10 production was significantly higher in cells from TNFR-KO mice than in cells from WT mice. Lipopolysaccharide-induced NO secretion by splenic macrophages in vitro was significantly reduced but systemic NO3−levels were similar in infected TNFR-KO and WT mice.
Lipopolysaccharide (LPS)-Binding Synthetic Peptides Derived from Serum Amyloid P Component Neutralize LPS
Authors: de Haas Carla J. C. , van der Zee Ruurd , Benaissa-Trouw Barry , van Kessel Kok P. M. , Verhoef Jan , van Strijp Jos A. G. 
Published: December 2019

ABSTRACTLipopolysaccharide (LPS) is the major mediator of gram-negative septic shock. Molecules that bind LPS and neutralize its toxic effects could have important clinical applications. We showed that serum amyloid P component (SAP) neutralizes LPS. A SAP-derived peptide, consisting of amino acids 27 to 39, inhibited LPS-mediated effects in the presence of human blood. In this study, we used a pepscan of overlapping 15-mer peptides and distinguished two additional LPS-binding regions within the SAP molecule, identified in the regions spanning amino acids 61 to 75 and 186 to 200. The corresponding SAP-derived peptides, pep61-75 and pep186-200, inhibited the binding of fluorescein isothiocyanate-labeled LPS to monocytes as efficiently as a bactericidal/permeability-increasing protein (BPI)-derived 15-mer peptide comprising amino acids 85 to 99. The same SAP-derived peptides very potently inhibited LPS-induced priming of phagocytes in human blood. Also, SAP-derived pep186-200 caused a prolonged survival of actinomycin D-sensitized mice treated with LPS to induce septic shock, indicating a potential use of this peptide in the defense against serious gram-negative sepsis in humans.
Evaluation ofSalmonella typhimuriumMutants in a Model of Experimental Gastroenteritis
Authors: Everest Paul , Ketley Julian , Hardy Simon , Douce Gill , Khan Shahid , Shea Jacqui , Holden David , Maskell Duncan , Dougan Gordon 
Published: December 2019

ABSTRACTSalmonella typhimuriumstrains harboring independent, defined mutations inaroA,invA,ssrA, ormsbBwere assessed for their ability to induce fluid accumulation, tissue damage, and local inflammation in rabbit ileal loops. Three wild-type strains ofS. typhimurium, TML, HWSH, and SL1344, and two mutant strains,S. typhimuriumSL1344ssrAandS. typhimuriumSL1344msbB, consistently induced fluid accumulation in the lumen of loops and inflammation of loop-associated tissues. In contrast, three differentS. typhimurium aroAstrains and aninvAmutant of SL1344 did not induce significant fluid accumulation in the rabbit ileal loops. However, theS. typhimurium aroAstrains did induce an inflammatory infiltrate and some local villus-associated damage, but theinvAmutant did not. Histologically, wild-typeS. typhimurium,S. typhimuriumSL1344ssrA, andS. typhimuriumSL1344msbBdemonstrated more severe effects on villus architecture thanS. typhimurium aroAstrains, whereasS. typhimurium invA-infected loops showed no detectable damage. This suggests that villus damage most likely contributes to fluid accumulation within the loop.
Effects of Cytokines and Endotoxin on the Intracellular Growth of Bacteria
Authors: Kanangat Siva , Meduri G. Umberto , Tolley Elizabeth A. , Patterson David R. , Meduri Christopher U. , Pak Chol , Griffin John P. , Bronze Michael S. , Schaberg Dennis R. 
Published: December 2019

ABSTRACTPatients with unresolving acute respiratory distress syndrome (ARDS) have persistently elevated levels of proinflammatory cytokines in the lungs and circulation and increased rates of bacterial infections. Phagocytic cells hyperactivated with lipopolysaccharide (LPS), which induces high levels of proinflammatory cytokines in monocytic cells, are inefficient in killing ingested bacteria despite having intact phagocytic activity. On the other hand, phagocytic cells that are activated with an analogue of LPS that does not induce the expression of proinflammatory cytokines effectively ingest and kill bacteria. We hypothesized that in the presence of high concentrations of proinflammatory cytokines, bacteria may adapt and utilize cytokines to their growth advantage. To test our hypothesis, we primed a human monocytic cell line (U937) with escalating concentrations of the proinflammatory cytokines tumor necrosis factor alpha, interleukin-1β (IL-1β), and IL-6 and with LPS. These cells were then exposed to fresh isolates of three common nosocomial pathogens:Staphylococcus aureus,Pseudomonas aeruginosa, and anAcinetobactersp. In human monocytes primed with lower concentrations of proinflammatory cytokines (10 to 250 pg) or LPS (1 and 10 ng), intracellular bacterial growth decreased. However, when human monocytes were primed with higher concentrations of proinflammatory cytokines (1 to 10 ng) or LPS (1 to 10 μg), intracellular growth of the tested bacteria increased significantly (P<0.0001). These results were reproduced with peripheral blood monocytes obtained from normal healthy volunteers. The specificity of the cytokine activity was demonstrated by neutralizing the cytokines with specific antibodies. Our findings provide a possible mechanism to explain the frequent development of bacterial infections in patients with an intense and protracted inflammatory response.
Role of Pneumolysin’s Complement-Activating Activity during Pneumococcal Bacteremia in Cirrhotic Rats
Authors: Alcantara Rosemarie B. , Preheim Laurel C. , Gentry Martha J. 
Published: December 2019

ABSTRACT

We investigated the role of pneumolysin’s complement-activating activity during
Streptococcus pneumoniae
bacteremia in a hypocomplementemic, cirrhotic host. Isogenic mutant pneumococcal strains, in which pneumolysin was expressed from a plasmid, were used. These strains included H+C+, expressing wild-type pneumolysin with both cytolytic and complement-activating activity; PLY−, carrying the plasmid without the pneumolysin gene; and, H+C−, expressing pneumolysin with cytolytic activity only. In control rats, intravenous infection with 2.0 × 10
7
CFU of H+C+ per ml of blood resulted in a decrease in bacteremia of 3.5 log units by 18 h postinfection and 55% mortality. By contrast, cirrhotic rats infected similarly with the H+C+ strain demonstrated a 0.2-log-unit increase in bacteremia by 18 h postinfection and 100% mortality. Both control and cirrhotic rats cleared the PLY− strain more effectively from their bloodstreams by 18 h postinfection (6.2 and 5.6 log unit decreases, respectively). Infection with the PLY− strain also resulted in low mortality (0 and 14%, respectively) for control and cirrhotic rats. When infected with the H+C− strain (without complement-activating activity), both groups cleared the organism from their bloodstreams nearly as well as they did the PLY− strain. Furthermore, the mortality rate for control and cirrhotic rats was identical after infection with the H+C− strain. These studies suggest that pneumolysin production contributes to decreased pneumococcal clearance from the bloodstream and higher mortality in both control and cirrhotic rats. However, pneumolysin’s complement-activating activity may uniquely enhance pneumococcal virulence in the hypocomplementemic, cirrhotic host.
Antibody Responses in the Lower Respiratory Tract and Male Urogenital Tract in Humans after Nasal and Oral Vaccination with Cholera Toxin B Subunit
Authors: Rudin Anna , Riise Gerdt C. , Holmgren Jan 
Published: December 2019

ABSTRACTNasal vaccine delivery is superior to oral delivery in inducing specific immunoglobulin A (IgA) and IgG antibody responses in the upper respiratory tract. Although an antibody response in the nasal passages is important in protecting against primary colonization with lung pathogens, antibodies in the lungs are usually required as well. We immunized 15 male volunteers twice nasally or orally with cholera toxin B subunit (CTB) and determined the specific antibody levels in serum, bronchoalveolar lavage (BAL) fluid, and urine before and 2 weeks after immunization. Nasal immunization induced fivefold increases in the levels of specific IgA antibodies in BAL fluid of most volunteers, whereas there were no significant specific IgA responses after oral immunization. The specific IgG antibody level increased eightfold in BAL fluid in the nasally vaccinated subjects, and the major part of IgG had most probably been transferred from serum. Since the specific IgG response in serum was lower in the individuals vaccinated orally, the IgG response in BAL fluid in this group was also lower and not significant. In conclusion, nasal immunization is also preferable to the oral route when vaccinating against lower respiratory tract infections, and a systemic immune response is considerably more important in the lower than in the upper respiratory tract. Moreover, both nasal and oral immunizations were able to stimulate 6- to 10-fold specific IgA and IgG responses in urine in about half of the individuals, which indicates that distant mucosal vaccination might be used to prevent adhesion of pathogens to the urogenital tract.
Deletion of
porA
by Recombination between Clusters of Repetitive Extragenic Palindromic Sequences in
Neisseria meningitidis
Authors: van der Ende A. , Hopman C. T. P. , Dankert J. 
Published: December 2019

ABSTRACT

PorA is an important component in a vaccine against infection with
Neisseria meningitidis
. However,
porA
-negative meningococci were isolated from patients, thereby potentially limiting the role of PorA-mediated immunity. To analyze the mechanism by which the
porA
deletion occurred, the regions upstream and downstream of
porA
from three meningococcal strains (H44/76, H355, and 860183) were sequenced. The
porA
upstream region in strain 860183 contains a cluster of 22 repetitive palindromic RS3 core sequences (ATTCCC-N
8
-GGGAAT) and 10 RS3 core sequences (ATTCCC) in direct orientation. The cluster is flanked by neisserial repeats, so-called Correia elements, and can be subdivided into three repeats of 518 bp followed by a truncated repeat. The
porA
upstream region of the other two strains showed deletions, probably caused by a recombination between RS3 core sequences. The
porA
downstream region of H44/76 and H355 contains the IS
1106
element followed by a cluster of 10 palindromic RS3 core sequences, 4 RS3 core sequences, and 1 other RS3 core sequence (GGGAAT) and is followed by a Correia element. This cluster can be subdivided into four direct repeats of 370 bp. Strain 860183 had two such repeats instead of four. Sequence analysis of the
porA
-negative variants indicated that the deletion of
porA
occurred via a recombination between two copies of the 116-bp region, containing two palindromic RS3 core sequences and a single RS3 core sequence. This region is homologous in the upstream and downstream clusters.
Lipid Extract ofMycoplasma penetransProteinase K-Digested Lipid-Associated Membrane Proteins Rapidly Activates NF-κB and Activator Protein 1
Authors: Feng Shaw-Huey , Lo Shyh-Ching 
Published: December 2019

ABSTRACTLipid-associated membrane proteins (LAMPs) ofMycoplasma penetransrapidly induced macrophages to produce proinflammatory cytokines such as tumor necrosis factor alpha (TNF-α). Our analysis showed that the macrophage-stimulating activity of TNF-α production was mainly attributable to a lipid extractable component(s) in the LAMP preparation. Since induction of gene expression is normally preceded by activation of transcriptional factors that bind to their specific recognition elements located in the upstream promoter region, we examined the activity of transcriptional factors, namely, NF-κB and activator protein 1 (AP-1), in thioglycolate exudate peritoneal (TEP) macrophages treated withM. penetranslipid extract of proteinase K (PK)-digested LAMPs. Initially, in the nuclei of unstimulated TEP cells, there was only a low basal level of active AP-1, and the active form of NF-κB could not be detected.M. penetranslipid extract of PK-digested LAMPs activated both NF-κB and AP-1 in TEP macrophages within 15 min. The markedly increased activities of both factors gradually declined and dissipated after 2 h. Parallel to the rapid increase of NF-κB and AP-1, the TNF-α transcript also increased significantly 15 min after the stimulation. The high-level expression of TNF-α persisted over 2 h. Dexamethasone blocked the activation of both NF-κB and AP-1 and suppressed the production of TNF-α in TEP macrophages stimulated byM. penetranslipid extract of PK-digested LAMPs. Our study demonstrates that theM. penetranslipid extract of PK-digested LAMP is a potent activator for NF-κB and AP-1 in murine TEP macrophages. Our results also suggest that high-level expression of TNF-α in cells induced byM. penetranslipid extract of PK-digested LAMPs is associated with rapid activation of transcriptional factors NF-κB and AP-1.
Prior Genital Tract Infection with a Murine or Human Biovar ofChlamydia trachomatisProtects Mice against Heterotypic Challenge Infection
Authors: Ramsey Kyle H. , Cotter Todd W. , Salyer Rena D. , Miranpuri Gurwattan S. , Yanez Michael A. , Poulsen Christoffer E. , DeWolfe Jennifer L. , Byrne Gerald I. 
Published: December 2019

ABSTRACTWe sought to assess the degree of cross-protective immunity in a mouse model of chlamydial genital tract infection. Following resolution of genital infection with the mouse pneumonitis (MoPn) biovar ofChlamydia trachomatis, mice were challenged intravaginally with either MoPn or human serovar E or L2. The majority of animals previously infected with MoPn were solidly immune to challenge with either of the two human biovars. Surprisingly, approximately 50% of animals became reinfected when homologously challenged with MoPn, although the secondary infection yielded significantly lower numbers of the organism isolated over a shorter duration than in the primary infection. Primary infection with serovar E also protected against challenge with MoPn or serovar L2, although the degree of immune protection was lower than that resulting from primary infection with MoPn. Blast transformation and assessment of delayed-type hypersensitivity indicated that mice previously infected with either human or murine biovars produced broadly cross-reactive T cells that recognized epitopes of either murine or human biovars ofC. trachomatis. Immunoblotting demonstrated that primary MoPn infection produced immunoglobulin G (IgG) antibody to antigens of MoPn as well as at least three distinct antigenic components of human serovar E, one of which was identical in molecular weight to the major outer membrane protein (MOMP). Primary infection with serovar E produced IgG antibody reactive against serovar E but not MoPn MOMP and against at least one ca. 60-kDa protein of both chlamydial strains. Our results indicate that primary genital infection of mice with murineC. trachomatisinduces immunity against challenge with either of two human biovars.
Porcine Epithelial β-Defensin 1 Is Expressed in the Dorsal Tongue at Antimicrobial Concentrations
Authors: Shi Jishu , Zhang Guolong , Wu Hua , Ross Christopher , Blecha Frank , Ganz Tomas 
Published: December 2019

ABSTRACT

Epithelial cells and phagocytes contain antimicrobial polypeptides that participate in innate host defense. A recently cloned porcine β-defensin, PBD-1, was detected by Northern organ blots exclusively in the tongue epithelium. We generated recombinant PBD-1 peptide by using a baculovirus-insect cell expression system and obtained two forms (PBD-1
42
and PBD-1
38
), which differed by N-terminal truncation. Only PBD-1
42
was found in scrapings of the surface of the dorsal tongue or the buccal mucosa. Immunohistochemical staining with antibody to PBD-1
42
revealed that PBD-1 was highly concentrated in an ∼0.1-mm-thick layer in the cornified tips of the filiform (but not fungiform) papillae of the dorsal tongue and in the superficial squamous cell layers of the buccal mucosa. By scraping, extraction, and semiquantitative Western blotting, the concentration of PBD-1 in the dorsal tongue surface and the buccal mucosa was estimated at 20 to 100 μg/ml. PBD-1 had antibacterial activity against
Escherichia coli
,
Salmonella typhimurium
,
Listeria monocytogenes
, and
Candida albicans
in 10 mM sodium phosphate buffer (pH 7.4). Added NaCl progressively inhibited the activity of PBD-1 against
E. coli
and
C. albicans
. In 10 mM sodium phosphate with 125 mM NaCl, the combinations of sublethal concentrations of PBD-1 and the porcine neutrophil peptide PG-3, PR-39, or PR-26 showed synergistic activity against
E. coli
or the multidrug-resistant
S. typhimurium
DT104. At its physiologic concentration, PBD-1 has antimicrobial effects under both low- and high-salt conditions encountered in the oral cavity and may contribute to the antimicrobial barrier properties of the dorsal tongue and oral epithelium.
FbpC Is Not Essential for Iron Acquisition in
Neisseria gonorrhoeae
Authors: Sebastian Shite , Genco Caroline Attardo 
Published: December 2019

ABSTRACT

The
fbpABC
locus of
Neisseria gonorrhoeae
has been proposed to encode a periplasmic protein-dependent iron transport system. Although the function of the gonococcal FbpA protein has been well characterized and its role as a periplasmic binding protein is well defined, little is known about the function of the FbpB and FbpC proteins. To define the function of the gonococcal FbpC protein, an
N. gonorrhoeae
F62
fbpC
mutant was constructed by insertional inactivation with the kanamycin gene. The
N. gonorrhoeae
F62
fbpC
mutant was observed to grow with heme, transferrin, or ferric nitrate as the sole exogenous iron source, indicating that the gonococcal FbpC protein is not absolutely required for growth with these iron sources. In previous studies we were unable to detect
fbpB
- or
fbpC
-specific transcripts by Northern analysis. Reverse transcription-PCR analysis with RNA obtained from
N. gonorrhoeae
F62 grown under iron-replete and -depleted conditions detected
fbpA
and
fbpAB
transcripts but failed to detect
fbpC
or
fbpBC
transcripts. These results indicate that FbpC does not play a pivotal role in iron transport in
N. gonorrhoeae
and suggest that additional ABC transport systems are functional in the gonococcus for the acquisition of iron.
Early Gene Expression of NK Cell-Activating Chemokines in Mice Resistant toLeishmania major
Authors: Vester Bettina , Müller Kerstin , Solbach Werner , Laskay Tamás 
Published: December 2019

ABSTRACTSusceptibility of mice toLeishmania majoris associated with an insufficient NK cell-mediated innate immune response. We analyzed the expression of NK cell-activating chemokines in vivo during the first days of infection in resistant and susceptible mice. The mRNA expression of gamma interferon-inducible protein 10 (IP-10), monocyte chemoattractant protein 1 (MCP-1), and lymphotactin was upregulated 1 day after infection in the draining lymph nodes of resistant C57BL/6 mice but not in those of susceptible BALB/c mice. In vivo local treatment of BALB/c mice with recombinant IP-10 shortly after infection resulted in an enhanced NK cell activity in the draining lymph node. The data suggest that although the recruitment of NK cells is normal in susceptible mice, the lack of NK cell-activating chemokines is a factor resulting in a suboptimal NK cell-mediated defense.
Immunity in Experimental Murine Filariasis: Roles of T and B Cells Revisited
Authors: Babu Subash , Shultz Leonard D. , Klei Thomas R. , Rajan T. V. 
Published: December 2019

ABSTRACTWe have reevaluated the contributions of T and B cells inBrugia malayiinfection by utilizing knockout mice on a uniform background (C57BL/6J). We find that B-cell-deficient mice are more permissive to infection than T-cell-deficient mice.
Effects of
Mycoplasma fermentans
incognitus on Differentiation of THP-1 Cells
Authors: Reyes Leticia , Davidson Maureen K. , Thomas Linda C. , Davis Jerry K. 
Published: December 2019

ABSTRACT

Mycoplasma fermentans
incognitus has been isolated from human tissue in patients both with and without AIDS who died of systemic infection.
M. fermentans
incognitus and other strains of
M. fermentans
have been associated with rheumatoid arthritis. While cell extracts of
M. fermentans
incognitus can induce changes in murine and human cells of the monocytic lineage, little is known about interactions of viable organisms with such cells. Because of the central role of macrophages in chronic inflammation, we examined the effects of
M. fermentans
incognitus on surface markers and functions of THP-1 cells, a well-characterized human monocytic cell line. This cell line has been used extensively in studies of macrophage differentiation, especially following exposure to phorbol esters. Changes in cell morphology, phagocytosis, rate of cell division, and selected surface markers were evaluated in cultures of THP-1 cells exposed to phorbol myristate acetate (PMA),
M. fermentans
incognitus, or both. As reported by other investigators, PMA induced THP-1 cells to differentiate into cells resembling tissue macrophages.
M. fermentans
incognitus only minimally affected changes induced by PMA, slightly increasing the percentage of cells positive for FCγRI and major histocompatibility complex (MHC) class II antigens.
M. fermentans
incognitus alone induced an incomplete arrest in the cell cycle at G
0
phase, increased phagocytic ability, and enhanced expression of FCγRI, CR3, CR4, and MHC class II antigens.