bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neisseria gonorrhoeaeElicits Membrane Ruffling and Cytoskeletal Rearrangements upon Infection of Primary Human Endocervical and Ectocervical Cells
Authors: Edwards Jennifer L. , Shao Jian Q. , Ault Kevin A. , Apicella Michael A. 
Published: July 2002

ABSTRACTNeisseria gonorrhoeaeis a strict human pathogen that is, primarily, transmitted by close sexual contact with an infected individual. Gonococcal infection of the male urogenital tract has been well studied in experimental human models and in urethral cell culture systems. Recent studies, using tissue culture cell systems, have suggested a role for the cervical epithelium in gonococcal infection of females; however, the nature of gonococcal infection of the normal uterine cervix remains controversial. To address this enigma, we have developed two primary human cervical epithelial cell systems from surgical biopsies. Gonococcal infection studies and electron microscopy show thatN. gonorrhoeaeis capable of infecting and invading both the endo- and the ectocervix. Invasion was found to occur primarily in an actin-dependent manner, but it does not appear to require de novo protein synthesis by either the bacterium or the host cervical cell. Membrane ruffles appear to be induced in response to gonococci. Consistent with membrane ruffling, gonococci were found residing within macropinosomes, and a concentrated accumulation of actin-associated proteins was observed to occur in response to gonococcal infection. Electron microscopy of clinically derived cervical biopsies show that lamellipodia formation and cytoskeletal changes, suggestive of membrane ruffles, also occur in the cervical epithelium of women with naturally acquired gonococcal cervicitis. These studies demonstrate the ability ofN. gonorrhoeaeto infect and invade both the endo- and the ectocervix of the normal uterine cervix. Gonococcal induced ruffling is a novel finding and may be unique to the cervical epithelium.
Mouse Toxicity and Cytokine Release by Verotoxin 1 B Subunit Mutants
Authors: Wolski Vince M. , Soltyk Anna M. , Brunton James L. 
Published: July 2002

ABSTRACT

The crystal structure of the verotoxin 1 (VT1) B subunit complexed with a globotriaosylceramide (Gb
3
) analogue showed the presence of three receptor binding sites per monomer. We wished to study the effects of altering the three sites, singly or in combination, on animal toxicity and cytokine induction in vitro. We found that while the site 1 and 2 mutants were modestly (two- to sevenfold) reduced in their ability to cause disease in BALB/c mice, the site 3 mutant, W34A, was as toxic as VT1. However, all the double-mutant proteins, irrespective of which two sites were mutated, exhibited approximately a 100-fold reduction in their 50% lethal doses for mice. These results suggest that multivalent receptor binding is important in vivo and that all three binding sites make a similar contribution to the latter process. The triple-mutant holotoxin, F30A G62T W34A, administered intraperitoneally without adjuvant, stimulated a strong antibody response in BALB/c mice, and the immune sera neutralized the activity of VT1 in vitro. Induction of tumor neurosis factor alpha release from differentiated human monocytes (THP-1 cells) was relatively impaired for site 1 and site 2 but not site 3 mutants, suggesting an auxiliary role for the latter site in mediation of cytokine release in vitro. Cytotoxicity assays on undifferentiated THP-1 cells have also demonstrated the importance of sites 1 and 2 and the relatively small role played by site 3 in causing cell death. These data suggest an association between the cytotoxicity of the protein and its ability to induce cytokine release.
Induction of Protective Immunity againstStreptococcus mutansColonization after Mucosal Immunization with AttenuatedSalmonella entericaSerovar Typhimurium Expressing anS. mutansAdhesin under the Control of In Vivo-InduciblenirBPromoter
Authors: Huang Yan , Hajishengallis George , Michalek Suzanne M. 
Published: July 2002

ABSTRACTThe purpose of the present study was to evaluate the effectiveness of an attenuatedSalmonella entericaserovar Typhimurium vaccine strain expressing the saliva-binding region (SBR) of theStreptococcus mutansantigen I/II adhesin, either alone or linked with the mucosal adjuvant cholera toxin A2 and B subunits (CTA2/B) and under the control of the anaerobically induciblenirBpromoter, in inducing a protective immune response againstS. mutansinfection. BALB/c mice were immunized by either the intranasal or the intragastric route with a single dose of 109or 1010SalmonellaCFU, respectively. TheSalmonellavaccine strain expressing an unrelated antigen (fragment C of tetanus toxin [TetC]) was also used for immunization as a control. Samples of serum and secretion (saliva and vaginal washes) were collected prior to and following immunization and assessed for antibody activity by enzyme-linked immunosorbent assay. Anti-SBR antibodies were detected in the serum and saliva of experimental animals by week 3 after immunization. A booster immunization at week 17 after the initial immunization resulted in enhanced immune responses to the SBR. The serum immunoglobulin G subclass profiles were indicative of T helper type 1 responses against both the vector and the SBR antigen. To determine the effectiveness of these responses on the protection againstS. mutansinfection, mice were challenged after the second immunization with a virulent strain ofS. mutanswhich was resistant to tetracycline and erythromycin. Prior to the challenge, mice were treated for 5 days with tetracycline, erythromycin, and penicillin.S. mutanswas initially recovered from all of the challenged mice. This bacterium persisted at high levels for at least 5 weeks in control TetC-immunized or nonimmunized mice despite the reappearance of indigenous oral organisms. However, mice immunized withSalmonellaclones expressing SBR or SBR-CTA2/B demonstrated a significant reduction in the number ofS. mutanspresent in plaque compared to the control groups. These results provide evidence for the effectiveness of theSalmonellavector in delivering the SBR antigen for the induction of mucosal and systemic immune responses to SBR. Furthermore, the induction of a salivary anti-SBR response corresponded with protection againstS. mutanscolonization of tooth surfaces.
Ureaplasma urealyticumModulates Endotoxin-Induced Cytokine Release by Human Monocytes Derived from Preterm and Term Newborns and Adults
Authors: Manimtim Winston M. , Hasday Jeffrey D. , Hester Lisa , Fairchild Karen D. , Lovchik Judith C. , Viscardi Rose M. 
Published: July 2002

ABSTRACTWe previously observed thatUreaplasma urealyticumrespiratory tract colonization in infants with a birth weight of ≤1,250 g was associated with increases in the tracheal aspirate proinflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8) relative to the counterregulatory cytokine IL-6 during the first week of life (A. M. Patterson, V. Taciak, J. Lovchik, R. E. Fox, A. B. Campbell, and R. M. Viscardi, Pediatr. Infect. Dis. J. 17:321–328, 1998). We hypothesized thatU. urealyticumalters the host immune response in the presence of a coinflammatory stimulus (e.g., bacterial infection or hyperoxia) by shifting the balance of cytokine expression towards the proinflammatory cytokines. To test this hypothesis, we compared the release of TNF-α, IL-8, IL-6, and IL-10 in vitro by unstimulated andU. urealyticum(with or without lipopolysaccharide [LPS])-stimulated human monocytes from adult peripheral blood and from term and preterm cord blood.U. urealyticumalone and in combination with LPS induced concentration- and development-dependent changes in cytokine release. In vitro inoculation with low-inoculumU. urealyticum(103color-changing units [CCU]) (i) partially blocked the LPS-stimulated IL-6 release by all cells and reduced LPS-stimulated IL-10 release by preterm cells, (ii) stimulated TNF-α and IL-8 release by preterm cells, and (iii) augmented LPS-stimulated TNF-α release in all cells. In preterm cells, high-inoculumU. urealyticum(106CCU) (i) stimulated TNF-α and IL-8, but not IL-6 or IL-10, release and (ii) augmented LPS-stimulated TNF-α and IL-8 release. High-inoculumU. urealyticum(i) stimulated release of all four cytokines in term cells and IL-8 release in adult cells and (ii) augmented LPS-induced TNF-α, IL-10, and IL-8 release in term cells but did not significantly affect LPS-induced cytokine release in adult cells. We speculate thatU. urealyticumenhances the proinflammatory response to a second infection by blocking expression of counterregulatory cytokines (IL-6 and IL-10), predisposing the preterm infant to prolonged and dysregulated inflammation, lung injury, and impaired clearance of secondary infections.
Neisseria meningitidis
RTX Protein FrpC Induces High Levels of Serum Antibodies during Invasive Disease: Polymorphism of
frpC
Alleles and Purification of Recombinant FrpC
Authors: Osička Radim , Kalmusová Jitka , Křı́žová Pavla , Šebo Peter 
Published: July 2002

ABSTRACT

The
Neisseria meningitidis
FAM20 strain secretes two proteins of unknown function, FrpA and FrpC, which contain typical RTX domains found in cytotoxins from other gram-negative pathogens. To evaluate whether the Frp proteins could be involved in meningococcal virulence, 65 isolates of all serogroups were screened by PCR for the presence of both
frp
genes. The
frpA
allele was, however, poorly conserved. A single strain harbored an
frpA
allele of the previously described size, while large insertions were detected in the
frpA
loci of 22 isolates (34%), and the 42 remaining isolates (65%) did not contain
frpA
at all. In contrast,
frpC
alleles, albeit of variable length, were detected in all invasive and most carrier strains. This suggests that meningococci may produce a family of FrpC proteins of various molecular masses. High levels of both immunoglobulin G (IgG) and IgA class antibodies recognizing recombinant FrpC were indeed detected in convalescent-phase sera of most patients at 2 and 4 to 5 weeks after the first symptoms of meningococcal disease. These results show that FrpC-like proteins are produced and may play a role in invasive meningococcal infections.
Central Role for Interleukin-4 in Regulating Nitric Oxide-Mediated Inhibition of T-Cell Proliferation and Gamma Interferon Production in Schistosomiasis
Authors: Patton Elisabeth A. , La Flamme Anne C. , Pedras-Vasoncelos Joao A. , Pearce Edward J. 
Published: July 2002

ABSTRACTSchistosoma mansoni-infected wild-type (WT) mice develop a Th2 response and chronic disease. In contrast, infected interleukin-4 double-deficient (IL-4−/−) mice develop a Th1-like response and an acute, lethal syndrome. Disease severity in these animals correlates with excessive and prolonged production of nitric oxide (NO) associated with enhanced antigen-driven gamma interferon (IFN-γ) production in the absence of IL-4. Strikingly, splenic lymphocytes from infected IL-4−/−mice failed to proliferate as well as those from infected WT mice following stimulation in vitro with antigen or anti-CD3 antibody. Contrary to antigen-driven IFN-γ responses, anti-CD3 antibody stimulation of splenocytes resulted in significantly less IFN-γ being produced by CD8 cells from infected IL-4−/−mice than by those from infected WT mice or normal mice. NO is largely responsible for the impaired T-cell functions in infected IL-4−/−mice, as inhibition of iNOS significantly enhanced proliferation and IFN-γ production.
Recombinant Tumor Necrosis Factor Alpha Does Not Inhibit the Growth of African Trypanosomes in Axenic Cultures
Authors: Kitani Hiroshi , Black Samuel J. , Nakamura Yoshio , Naessens Jan , Murphy Noel B. , Yokomizo Yuichi , Gibson John , Iraqi Fuad 
Published: July 2002

ABSTRACT

Mice whose tumor necrosis factor alpha (TNF-α) genes were disrupted developed higher levels of parasitemia than wild-type mice following infection with
Trypanosoma congolense
IL1180 or
T. brucei brucei
GUTat3.1, confirming the results of earlier studies. To determine whether TNF-α directly affects the growth of these and other bloodstream forms of African trypanosomes, we studied the effects of recombinant mouse, human, and bovine TNF-α on the growth of two isolates of
T. congolense
, IL1180 and IL3338, and two isolates of
T. brucei brucei
, GUTat3.1 and ILTat1.1, under axenic culture conditions. The preparations of recombinant TNF-α used were biologically active as determined by their capacity to kill L929 cells. Of five recombinant TNF-α lots tested, one lot of mouse TNF-α inhibited the growth of both isolates of
T. brucei brucei
and one lot of bovine TNF-α inhibited the growth of
T. brucei brucei
ILTat1.1 but only at very high concentrations and without causing detectable killing of the parasites. The other lots of mouse recombinant TNF-α, as well as human TNF-α, did not affect the growth of any of the test trypanosomes even at maximal concentrations that could be attained in the culture systems (3,000 to 15,000 U of TNF-α/ml of medium). These results suggest that exogenously added recombinant TNF-α generally does not inhibit the growth of African trypanosomes under the culture conditions we used. The impact of TNF-α on trypanosome parasitemia may be indirect, at least with respect to the four strains of trypanosomes reported here.
A Lytic Transglycosylase of
Neisseria gonorrhoeae
Is Involved in Peptidoglycan-Derived Cytotoxin Production
Authors: Cloud Karen A. , Dillard Joseph P. 
Published: July 2002

ABSTRACT

Neisseria gonorrhoeae
releases soluble fragments of peptidoglycan during growth. These molecules are implicated in the pathogenesis of various forms of gonococcal infection. A major peptidoglycan fragment released by gonococci is identical to the tracheal cytotoxin of
Bordetella pertussis
and has been shown to kill ciliated fallopian tube cells in organ culture. Previous studies indicated that a unique lytic peptidoglycan transglycosylase (AtlA) was responsible for some, but not all, of the peptidoglycan-derived cytotoxin (PGCT) production in certain gonococcal strains. To examine the role of other putative lytic transglycosylases in PGCT production, we made a deletion mutation in a gonococcal gene exhibiting similarity with genes encoding lytic transglycosylases from other bacterial species. The gonococcal mutant was viable and grew normally, but it was less autolytic than the wild-type strain in stationary-phase culture and under nongrowth conditions. The gonococcal mutant was reduced in peptidoglycan turnover, and the profile of the released products showed a reduction in monomeric peptidoglycan. Proportionally more multimeric fragments were released. These results suggest that this gonococcal gene (
ltgA
) encodes a lytic peptidoglycan transglycosylase and that it is responsible for a significant proportion of the PGCT released by
N. gonorrhoeae
.
Identification of the Lipooligosaccharide Biosynthesis Gene
lic2B
as a Putative Virulence Factor in Strains of Nontypeable
Haemophilus influenzae
That Cause Otitis Media
Authors: Pettigrew M. M. , Foxman B. , Marrs C. F. , Gilsdorf J. R. 
Published: July 2002

ABSTRACT

Nontypeable (NT) strains of
Haemophilus influenzae
are an important cause of acute otitis media (OM). The pathogenic process by which NT
H. influenzae
strains cause OM is poorly understood. In order to identify specific virulence factors important for OM pathogenesis, genomic subtraction of the NT
H. influenzae
middle ear isolate G622 against
H. influenzae
strain Rd was conducted and the resulting subtraction products were used to screen a panel of
H. influenzae
isolates. Subtraction identified 36 PCR fragments unique to strain G622, which were used in a preliminary screen of 48 middle ear isolates and 46 nasopharyngeal and throat isolates to identify genes found more frequently among middle ear isolates. These experiments identified a PCR fragment with high homology to the lipooligosaccharide biosynthesis gene
lic2B
(originally identified in an
H. influenzae
type b strain) among 52% of the middle ear isolates and 9% of nasopharyngeal and throat isolates. The
lic2B
gene cloned from NT
H. influenzae
strain G622 was 99% identical at the amino acid level to that of the
H. influenzae
type b strain RM7004. The
lic2B
gene was used to screen a larger panel of
H. influenzae
isolates including the original 48 middle ear isolates, 40 invasive type b isolates, 90 NT
H. influenzae
throat isolates from children attending day care, and 32 NT
H. influenzae
nasopharyngeal clinical isolates. The
lic2B
gene was found 3.7 times more frequently among middle ear isolates than in throat isolates from children attending day care. These data suggest that a specific NT
H. influenzae
gene is associated with OM.
Cloning and Expression of Two Genes Coding for Sodium Pumps in the Salt-Tolerant Yeast
Debaryomyces hansenii
Authors: Almagro Anabel , Prista Catarina , Benito Begoña , Loureiro-Dias Maria C. , Ramos José 
Published: July 2002

ABSTRACT

Two genes encoding Na
+
-ATPases from
Debaryomyces hansenii
were cloned and sequenced. The genes, designated
ENA1
from
D. hansenii
(
DhENA1
) and
DhENA2
, exhibited high homology with the corresponding genes from
Schwanniomyces occidentalis. DhENA1
was expressed in the presence of high Na
+
concentrations, while the expression of
DhENA2
also required high pH. A mutant of
Saccharomyces cerevisiae
lacking the Na
+
efflux systems and sensitive to Na
+
, when transformed with
DhENA1
or
DhENA2
, recovered Na
+
tolerance and also the ability to extrude Na
+
.
Binary Typing of
Staphylococcus aureus
Strains through Reversed Hybridization Using Digoxigenin-Universal Linkage System-Labeled Bacterial Genomic DNA
Authors: van Leeuwen Willem , Libregts Christel , Schalk Marjolijn , Veuskens Jack , Verbrugh Henri , van Belkum Alex 
Published: July 2002

ABSTRACT

A novel binary typing (BT) procedure, based on reversed hybridization of digoxigenin-universal linkage system-labeled bacterial DNA to strip-immobilized probes, is presented. Chromogenic detection of hybrids was performed.
Staphylococcus aureus
isolates (
n
= 20) were analyzed to establish the feasibility of BT. A technically simple and fast procedure has been developed for application in routine microbiology laboratories.
Accuracy of the VITEK 2 System To Detect Glycopeptide Resistance in Enterococci
Authors: van den Braak Nicole , Goessens Wil , van Belkum Alex , Verbrugh Henri A. , Endtz Hubert P. 
Published: July 2002

ABSTRACT

We evaluated the accuracy of the VITEK 2 fully automated system to detect and identify glycopeptide-resistant enterococci (GRE) compared to a reference agar dilution method. The sensitivity of vancomycin susceptibility testing with VITEK 2 for the detection of
vanA
,
vanB
, and
vanC1
strains was 100%. The sensitivity of vancomycin susceptibility testing of
vanC2
strains was 77%. The sensitivity of teicoplanin susceptibility testing of
vanA
strains was 90%. Of 80
vanC
enterococci, 78 (98%) were correctly identified by VITEK 2 as
Enterococcus gallinarum/Enterococcus casseliflavus
. Since the identification and susceptibility data are produced within 3 and 8 h, respectively, VITEK 2 appears a fast and reliable method for detection of GRE in microbiology laboratories.
Rapid Detection of
Mycobacterium tuberculosis
in Contaminated BACTEC 12B Broth Cultures by Testing with Amplified Mycobacterium Tuberculosis Direct Test
Authors: Zheng Xiaotian , Pang Minnie , Engler Howard D. , Tanaka Sherri , Reppun Thomas 
Published: July 2002

ABSTRACT

Contamination of broth cultures of acid-fast bacilli (AFB) by bacterial species other than
Mycobacterium
species frequently occurs. Many of these contaminated cultures require redecontamination and reincubation before the appropriate tests can be performed for identification, significantly affecting the turnaround time for reporting culture results. In this study, the Amplified Mycobacterium Tuberculosis Direct Test (MTD; Gen-Probe) was performed to detect the
Mycobacterium tuberculosis
complex (MTBC) in 125 BACTEC 12B broth cultures with positive growth indices. Among these, 41 grew non-AFB bacteria only, and all 41 were negative by the MTD. The remaining 84 bottles contained contaminated cultures that grew both AFB and other bacteria or yeasts. Repeat decontamination and reincubation of these specimens required a mean time of 13 days (range, 3 to 40 days). The MTD results were positive for 10 samples, 9 of which were MTBC culture positive and 1 of which grew
Myobacterium celatum
, a species known to cross-react in the MTD. All cultures growing other mycobacterial species were negative by the MTD. The results of this study demonstrate that the MTD is both sensitive and specific in detecting MTBC in contaminated broth cultures and that, when used selectively, the MTD can potentially rule in or out a diagnosis of MTBC as much as 12 days earlier than using nonamplified DNA probe testing alone can.
High Prevalence of Granulocytic Ehrlichiae and
Borrelia burgdorferi
Sensu Lato in
Ixodes ricinus
Ticks from Bulgaria
Authors: Christova Iva , Schouls Leo , van de Pol Ingrid , Park Jinho , Panayotov Stefan , Lefterova Viktoria , Kantardjiev Todor , Dumler J. Stephen 
Published: July 2002

ABSTRACT

Bulgarian
Ixodes ricinus
ticks were examined for
Ehrlichia
and
Borrelia
coinfection: 34 and 32% of adult ticks and at least 2 and 10% of nymphs were positive for these infections, respectively. Coinfections and dual or triple
Borrelia
infections were frequent, although
Ehrlichia phagocytophila
heterogeneity was minimal. Multiple tick-borne bacteria coexist in
I. ricinus
ticks in southeastern Europe.
Genome Typing of Adenovirus Type 34 Isolated in Two Cases of Conjunctivitis in Sapporo, Japan
Authors: Saitoh-Inagawa Waka , Tanaka Keico , Uchio Eiichi , Itoh Norihiko , Ohno Shigeaki , Aoki Koki 
Published: July 2002

ABSTRACT
Two cases of conjunctivitis caused by adenovirus type 34 (Ad34) are reported. The isolates were identified as Ad34 by the neutralization test and the PCR-sequence method of the hexon gene but as Ad14 by PCR-restriction fragment length polymorphism analysis. The genome types of these two isolates were identical to that of Ad34a.
Evaluation of the
Mycobacterium bovis
Restriction Fragment Length Polymorphism Probe pUCD, in Combination with the Direct Repeat Probe, for Molecular Typing of
Mycobacterium tuberculosis
Strains in Ireland
Authors: Cameron Henrietta , O'Brien Rory , Murray Anthony , Cryan Bartley , Hone Rosemary , Rogers Mark 
Published: July 2002

ABSTRACT

A mycobacterial restriction fragment length polymorphism probe, pUCD, has recently been described which represents an effective tool for the strain typing of
Mycobacterium bovis
. The present study evaluated this probe, in combination with the direct repeat probe (DR), for the molecular typing of 90 strains of
Mycobacterium tuberculosis
from 87 patients, looking at a group (62 isolates) of nonselected samples to assess pUCD combined with DR as a general tool and a subset of 32 isolates with a common specific IS
6110
strain type in Ireland. Within the group of 62 isolates, pUCD-DR identified 42 strains and was comparable to both IS
6110
(41 strains) and polymorphic guanine-cytosine-rich sequence (PGRS) (37 strains) analysis. pUCD-DR was found to be comparable to IS
6110
and PGRS in identifying four separate clusters of isolates which were confirmed to be clinically related. pUCD-DR divided the common IS
6110
isolates into six distinct types and was comparable to PGRS (seven strain types). The usefulness of this probe as an epidemiological tool is discussed.