bluuebunny/crossref_metadata_2025_split huggingface dataset:
Perspectives on Health Among Adult Users of Illicit Stimulant Drugs in Rural Ohio
Authors: Siegal Harvey A. , Draus Paul J. , Carlson Robert G. , Falck Russel S. , Wang Jichuan 
Published: March 2006

ABSTRACT:
Context: Although the nonmedical use of stimulant drugs such as cocaine and methamphetamine is increasingly common in many rural areas of the United States, little is known about the health beliefs of people who use these drugs. Purpose: This research describes illicit stimulant drug users’ views on health and health‐related concepts that may affect their utilization of health care services. Methods: A respondent‐driven sampling plan was used to recruit 249 not‐in‐treatment, nonmedical stimulant drug users who were residing in 3 rural counties in west central Ohio. A structured questionnaire administered by trained interviewers was used to collect information on a range of topics, including current drug use, self‐reported health status, perceived need for substance abuse treatment, and beliefs about health and health services. Findings: Participants reported using a wide variety of drugs nonmedically, some by injection. Alcohol and marijuana were the most commonly used drugs in the 30 days prior to the interview. Powder cocaine was used by 72.3% of the sample, crack by 68.3%, and methamphetamine by 29.7%. Fair or poor health status was reported by 41.3% of the participants. Only 20.9% of the sample felt they needed drug abuse treatment. Less than one third of the sample reported that they would feel comfortable talking to a physician about their drug use, and 65.1% said they preferred taking care of their problems without getting professional help. Conclusions: Stimulant drug users in rural Ohio are involved with a range of substances and hold health beliefs that may impede health services utilization.
Gating of the expressed T‐type Cav3.1 calcium channels is modulated by Ca2+
Authors: Lacinová L. , Kurejová M. , Klugbauer N. , Hofmann F. 
Published: March 2006

AbstractAim:  We have investigated the influence of Ca2+ ions on the basic biophysical properties of T‐type calcium channels.Methods:  The Cav3.1 calcium channel was transiently expressed in HEK 293 cells. Current was measured using the whole cell patch clamp technique. Ca2+ or Na+ ions were used as charge carriers. The intracellular Ca2+ was either decreased by the addition of 10 mm ethyleneglycoltetraacetic acid (EGTA) or increased by the addition of 200 μm Ca2+ into the non‐buffered intracellular solution. Various combinations of extra‐ and intracellular solutions yielded high, intermediate or low intracellular Ca2+ levels.Results:  The amplitude of the calcium current was independent of intracellular Ca2+ concentrations. High levels of intracellular Ca2+ accelerated significantly both the inactivation and the activation time constants of the current. The replacement of extracellular Ca2+ by Na+ as charge carrier did not affect the absolute value of the activation and inactivation time constants, but significantly enhanced the slope factor of the voltage dependence of the inactivation time constant. Slope factors of voltage dependencies of channel activation and inactivation were significantly enhanced. The recovery from inactivation was faster when Ca2+ was a charge carrier. The number of available channels saturated for membrane voltages more negative than −100 mV for the Ca2+ current, but did not reach steady state even at −150 mV for the Na+ current.Conclusions:  Ca2+ ions facilitate transitions of Cav3.1 channel from open into closed and inactivated states as well as backwards transition from inactivated into closed state, possibly by interacting with its voltage sensor.
Leukotoxin Confers Beta-Hemolytic Activity to
Actinobacillus actinomycetemcomitans
Authors: Balashova Nataliya V. , Crosby Juan A. , Al Ghofaily Lourdes , Kachlany Scott C. 
Published: March 2006

ABSTRACT

Actinobacillus actinomycetemcomitans
is the etiologic agent of localized aggressive periodontitis, a rapidly progressing oral disease that occurs in adolescents.
A. actinomycetemcomitans
can also cause systemic disease, including infective endocarditis. In early work on
A. actinomycetemcomitans
workers concluded that this bacterium is not beta-hemolytic. More recent reports have suggested that
A. actinomycetemcomitans
does have the potential to be beta-hemolytic. While growing
A. actinomycetemcomitans
on several types of growth media, we noticed a beta-hemolytic reaction on media from one manufacturer. Beta-hemolysis occurred on Columbia agar from Accumedia with either sheep or horse blood, but not on similar media from other manufacturers. A surprising result was that mutants of
A. actinomycetemcomitans
defective for production of leukotoxin, a toxin that is reportedly highly specific for only human and primate white blood cells, are not beta-hemolytic. Purified leukotoxin was able to lyse sheep and human erythrocytes in vitro. This work showed that in contrast to the accepted view,
A. actinomycetemcomitans
leukotoxin can indeed destroy erythrocytes and that the production of this toxin results in beta-hemolytic colonies on solid medium. In light of these results, the diagnostic criteria for clinical identification of
A. actinomycetemcomitans
and potentially related bacteria should be reevaluated. Furthermore, in studies on
A. actinomycetemcomitans
leukotoxin workers should now consider this toxin's ability to destroy red blood cells.
Analysis of Involvement of the RecF Pathway in
p44
Recombination in
Anaplasma phagocytophilum
and in
Escherichia coli
by Using a Plasmid Carrying the
p44
Expression and
p44
Donor Loci
Authors: Lin Quan , Zhang Chunbin , Rikihisa Yasuko 
Published: March 2006

ABSTRACT

Anaplasma phagocytophilum
, the etiologic agent of human granulocytic anaplasmosis, has a large paralog cluster (approximate 90 members) that encodes the 44-kDa major outer membrane proteins (P44s). Gene conversion at a single
p44
expression locus leads to P44 antigenic variation. Homologs of genes for the RecA-dependent RecF pathway, but not the RecBCD or RecE pathways, of recombination were detected in the
A. phagocytophilum
genome. In the present study, we examined whether the RecF pathway is involved in
p44
gene conversion. The recombination intermediate structure between a donor
p44
and the
p44
expression locus of
A. phagocytophilum
was detected in an HL-60 cell culture by Southern blot analysis followed by sequencing the band and in blood samples from infected SCID mice by PCR, followed by sequencing. The sequences were consistent with the RecF pathway recombination: a half-crossover structure, consisting of the donor
p44
locus connected to the 3′ conserved region of the recipient
p44
in the
p44
expression locus in direct orientation. To determine whether the
p44
recombination intermediate structure can be generated in a RecF-active
Escherichia coli
strain, we constructed a double-origin plasmid carrying the
p44
expression locus and a donor
p44
locus and introduced the plasmid into various
E. coli
strains. The recombination intermediate was recovered in an
E. coli
strain with active RecF recombination pathway but not in strains with deficient RecF pathway. Our results support the view that the
p44
gene conversion in
A. phagocytophilum
occurs through the RecF pathway.
Intranasal Vaccination with a Defined AttenuatedFrancisella novicidaStrain Induces Gamma Interferon-Dependent Antibody-Mediated Protection against Tularemia
Authors: Pammit Michael A. , Raulie Erin K. , Lauriano Crystal M. , Klose Karl E. , Arulanandam Bernard P. 
Published: March 2006

ABSTRACTFrancisella tularensisis an intracellular gram-negative bacterium that is the causative agent of tularemia and a potential bioweapon. We have characterized the efficacy of a definedF. novicidamutant (ΔiglC) as a live attenuated vaccine against subsequent intranasal challenge with the wild-type organism. Animals primed with theF. novicida ΔiglC(KKF24) mutant induced robust splenic gamma interferon (IFN-γ) and interleukin-12 (IL-12) recall responses with negligible IL-4 production as well as the production of antigen-specific serum immunoglobulin G1 (IgG1) and IgG2a antibodies. BALB/c mice vaccinated intranasally (i.n.) with KKF24 and subsequently challenged with wild-typeF. novicida(100 and 1,000 50% lethal doses) were highly protected (83% and 50% survival, respectively) from the lethal challenges. The protection conferred by KKF24 vaccination was shown to be highly dependent on endogenous IFN-γ production and also was mediated by antibodies that could be adoptively transferred to naive B-cell-deficient mice by inoculation of immune sera. Collectively, the results demonstrate that i.n. vaccination with KKF24 induces a vigorous Th1-type cytokine and antibody response that is protective against subsequent i.n. challenge with the wild-type strain. This is the first report of a defined live attenuated strain providing protection against the inhalation ofF. novicida.
An Increase in Antimycobacterial Th1-Cell Responses by Prime-Boost Protocols of Immunization Does Not Enhance Protection against Tuberculosis
Authors: Majlessi Laleh , Simsova Marcela , Jarvis Zdenka , Brodin Priscille , Rojas Marie-Jésus , Bauche Cécile , Nouzé Clémence , Ladant Daniel , Cole Stewart T. , Sebo Peter , Leclerc Claude 
Published: March 2006

ABSTRACTBordetella pertussisadenylate cyclase (CyaA) toxoid is a powerful nonreplicative immunization vector targeting dendritic cells, which has already been used successfully in prophylactic and therapeutic vaccination in various preclinical animal models. Here, we investigated the potential of CyaA, harboring strong mycobacterial immunogens, i.e., the immunodominant regions of antigen 85A or the complete sequence of the 6-kDa early secreted antigenic target (ESAT-6) protein, to induce antimycobacterial immunity. By generating T-cell hybridomas or by using T cells from mice infected with mycobacteria, we first demonstrated that the in vitro delivery of 85A or ESAT-6 to antigen-presenting cells by CyaA leads to processing and presentation, by major histocompatibility complex class II molecules, of the same epitopes as those displayed upon mycobacterial infection. Importantly, compared to the recombinant protein alone, the presentation of ESAT-6 in vitro was 100 times more efficient upon its delivery to antigen-presenting cells in fusion to CyaA. Immunization with CyaA-85A or CyaA-ESAT-6 in the absence of any adjuvant induced strong antigen-specific lymphoproliferative, interleukin-2 (IL-2) and gamma interferon (IFN-γ) cytokine responses, in the absence of any IL-4 or IL-5 production. When used as boosters after priming with a BCG expressing ESAT-6, the CyaA-85A and CyaA-ESAT-6 proteins were able to strikingly increase the sensitivity and intensity of proliferative and Th1-polarized responses and notably the frequency of antigen-specific IFN-γ-producing CD4+T cells. However, immunization with these CyaA constructs as subunit vaccines alone or as boosters did not allow induction or improvement of protection againstMycobacterium tuberculosisinfection. These results question the broadly admitted correlation between the frequency of IFN-γ-producing CD4+T cells and the level of protection against tuberculosis.
Immunization with
Staphylococcus aureus
Clumping Factor B, a Major Determinant in Nasal Carriage, Reduces Nasal Colonization in a Murine Model
Authors: Schaffer Adam C. , Solinga Robert M. , Cocchiaro Jordan , Portoles Marta , Kiser Kevin B. , Risley Allison , Randall Suzanne M. , Valtulina Viviana , Speziale Pietro , Walsh Evelyn , Foster Timothy , Lee Jean C. 
Published: March 2006

ABSTRACT

Staphylococcus aureus
is responsible for a wide range of infections, including soft tissue infections and potentially fatal bacteremias. The primary niche for
S. aureus
in humans is the nares, and nasal carriage is a documented risk factor for staphylococcal infection. Previous studies with rodent models of nasal colonization have implicated capsule and teichoic acid as staphylococcal surface factors that promote colonization. In this study, a mouse model of nasal colonization was utilized to demonstrate that
S. aureus
mutants that lack clumping factor A, collagen binding protein, fibronectin binding proteins A and B, polysaccharide intercellular adhesin, or the accessory gene regulator colonized as well as wild-type strains colonized. In contrast, mutants deficient in sortase A or clumping factor B (ClfB) showed reduced nasal colonization. Mice immunized intranasally with killed
S. aureus
cells showed reduced nasal colonization compared with control animals. Likewise, mice that were immunized systemically or intranasally with a recombinant vaccine composed of domain A of ClfB exhibited lower levels of colonization than control animals exhibited. A ClfB monoclonal antibody (MAb) inhibited
S. aureus
binding to mouse cytokeratin 10. Passive immunization of mice with this MAb resulted in reduced nasal colonization compared with the colonization observed after immunization with an isotype-matched control antibody. The mouse immunization studies demonstrate that ClfB is an attractive component for inclusion in a vaccine to reduce
S. aureus
nasal colonization in humans, which in turn may diminish the risk of staphylococcal infection. As targets for vaccine development and antimicrobial intervention are assessed, rodent nasal colonization models may be invaluable.
Pore-Forming and Enzymatic Activities ofBordetella pertussisAdenylate Cyclase Toxin Synergize in Promoting Lysis of Monocytes
Authors: Basler Marek , Masin Jiri , Osicka Radim , Sebo Peter 
Published: March 2006

ABSTRACTBordetellaadenylate cyclase (AC) toxin-hemolysin (CyaA) targets myeloid phagocytes expressing the αMβ2integrin (CD11b/CD18) and delivers into their cytosol an AC enzyme that converts ATP into cyclic AMP (cAMP). In parallel, CyaA acts as a hemolysin, forming small membrane pores. Using specific mutations, we dissected the contributions of the two activities to cytolytic potency of CyaA on J774A.1 murine monocytes. The capacity of AC to penetrate cells and deplete cytosolic ATP was essential for promoting lysis and the enzymatically inactive but fully hemolytic CyaA-AC−toxoid exhibited a 15-fold-lower cytolytic capacity on J774A.1 cells than intact CyaA. Moreover, a two- or fourfold drop of specific hemolytic activity of the CyaA-E570Q and CyaA-E581P mutants was overpowered by an intact capacity to dissipate cytosolic ATP into cAMP, allowing the less hemolytic proteins to promote lysis of J774A.1 cells as efficiently as intact CyaA. However, an increased hemolytic activity, due to lysine substitutions of glutamates 509, 516, and 581 in the pore-forming domain, conferred on AC−toxoids a correspondingly enhanced cytolytic potency. Moreover, a threefold increase in hemolytic activity could override a fourfold drop in capacity to convert cellular ATP to cAMP, conferring on the CyaA-E581K construct an overall twofold increased cytolytic potency. Hence, although appearing auxiliary in cytolytic action of the toxin on nucleated cells, the pore-forming activity can synergize with ATP-depleting activity of the cell-invasive AC enzyme and complement its action toward maximal cytotoxicity.
A Novel
Staphylococcus aureus
Vaccine: Iron Surface Determinant B Induces Rapid Antibody Responses in Rhesus Macaques and Specific Increased Survival in a Murine
S. aureus
Sepsis Model
Authors: Kuklin Nelly A. , Clark Desmond J. , Secore Susan , Cook James , Cope Leslie D. , McNeely Tessie , Noble Liliane , Brown Martha J. , Zorman Julie K. , Wang Xin Min , Pancari Gregory , Fan Hongxia , Isett Kevin , Burgess Bruce , Bryan Janine , Brownlow Michelle , George Hugh , Meinz Maria , Liddell Mary E. , Kelly Rosemarie , Schultz Loren , Montgomery Donna , Onishi Janet , Losada Maria , Martin Melissa , Ebert Timothy , Tan Charles Y. , Schofield Timothy L. , Nagy Eszter , Meineke Andreas , Joyce Joseph G. , Kurtz Myra B. , Caulfield Michael J. , Jansen Kathrin U. , McClements William , Anderson Annaliesa S. 
Published: March 2006

ABSTRACT

Staphylococcus aureus
is a major cause of nosocomial infections worldwide, and the rate of resistance to clinically relevant antibiotics, such as methicillin, is increasing; furthermore, there has been an increase in the number of methicillin-resistant
S. aureus
community-acquired infections. Effective treatment and prevention strategies are urgently needed. We investigated the potential of the
S. aureus
surface protein iron surface determinant B (IsdB) as a prophylactic vaccine against
S. aureus
infection. IsdB is an iron-sequestering protein that is conserved in diverse
S. aureus
clinical isolates, both methicillin resistant and methicillin sensitive, and it is expressed on the surface of all isolates tested. The vaccine was highly immunogenic in mice when it was formulated with amorphous aluminum hydroxyphosphate sulfate adjuvant, and the resulting antibody responses were associated with reproducible and significant protection in animal models of infection. The specificity of the protective immune responses in mice was demonstrated by using an
S. aureus
strain deficient for IsdB and HarA, a protein with a high level of identity to IsdB. We also demonstrated that IsdB is highly immunogenic in rhesus macaques, inducing a more-than-fivefold increase in antibody titers after a single immunization. Based on the data presented here, IsdB has excellent prospects for use as a vaccine against
S. aureus
disease in humans.
Efficient Translocation of EspC into Epithelial Cells Depends on Enteropathogenic
Escherichia coli
and Host Cell Contact
Authors: Vidal Jorge E. , Navarro-García Fernando 
Published: March 2006

ABSTRACT

EspC is an autotransporter protein secreted by enteropathogenic
Escherichia coli
(EPEC). The pathogenic role of EspC in EPEC infection is unknown. We have shown that the purified EspC produces enterotoxicity and cytotoxicity; for the latter effect, EspC must be internalized. However, the internalization mechanism is unknown. Here we show that azithromycin (an inhibitor of pinocytosis), but not drugs affecting caveole-, clathrin-, or receptor-mediated endocytosis, inhibited purified EspC internalization and cytoskeletal disruption, suggesting that purified EspC is internalized by pinocytosis. Furthermore, unlike in cholera toxin, we were unable to detect a receptor on epithelial cells by pretreatment at 4°C. Upon EspC entry, it is delivered directly into the cell cytosol, as shown by the fact that drugs that inhibit intracellular trafficking had no effect on cytoskeletal disruption. All these data suggest that purified EspC internalization is not a physiological internalization mechanism; hence, we explored EspC internalization during the infection of epithelial cells by EPEC. Like other EPEC virulence factors, EspC secretion is stimulated by EPEC when it is grown in cell culture medium and enhanced by the presence of epithelial cells. Physiologically secreted EspC was efficiently internalized during EPEC and host cell interaction. Additionally, the lack of EspC internalization caused by using an isogenic mutant prevented the cytopathic effect caused by EPEC. These data suggest that EPEC uses an efficient mechanism to internalize milieu-secreted EspC into epithelial cells; once inside the cells, EspC is able to induce the cytopathic effect caused by EPEC.
Characterization ofBacteroides fragilisHemolysins and Regulation and Synergistic Interactions of HlyA and HlyB
Authors: Robertson Kirstin P. , Smith C. Jeffrey , Gough Andrea M. , Rocha Edson R. 
Published: March 2006

ABSTRACTThis study describes the presence of 10 hemolysin orthologs in the genome of the opportunistic human anaerobic pathogenBacteroides fragilis, which is currently classified as a nonhemolytic bacterium. The hemolysins were designated HlyA through HlyI plus HlyIII. All cloned hemolysin genes were able to confer hemolytic activity to a nonhemolyticEscherichia colistrain on blood agar plates. Interestingly, HlyH was found to be present in the genome of theB. fragilisNCTC9343 strain but absent in strains 638R, YCH46, andBacteroides thetaiotaomicronVPI-5482. The hemolysins HlyA, HlyB, and HlyIII were selected for further characterization. HlyA, HlyB, and HlyIII were cytolytic to erythrocytes on liquid hemolytic assay. WhenhlyAandhlyBwere expressed together in a nonhemolyticE. colistrain, the strain showed enhanced hemolytic activity on blood agar plates. Further analysis revealed that HlyA and HlyB have synergistic hemolytic activity as detected by the liquid hemolytic assay. In addition, the two-component hemolysins HlyA and HlyB form a protein-protein complex in vivo as determined by bacterial two-hybrid system assay. ThehlyBandhlyAgenes are organized in an operon that is coordinately regulated by iron and oxygen. Northern blot hybridization analysis revealed thathlyBAwere expressed as a bicistronic mRNA induced approximately 2.5-fold under low-iron conditions and repressed in iron-rich medium. The normal iron-regulated expression ofhlyBAmRNA was lost in thefurAmutant strain. In contrast, thehlyAgene was also expressed as a single mRNA in iron-rich medium, but its expression was reduced approximately threefold under low-iron conditions in a Fur-independent manner. This suggests thathlyAalone is regulated by an unidentified iron-dependent regulator. Moreover, the expression levels ofhlyBAandhlyAwere reduced about threefold following oxygen exposure and treatment with hydrogen peroxide. Taken together, these results suggest that iron and oxidative stress have an effect on the control ofhlyBAandhlyAtranscriptional levels. AhlyBAmutant was constructed, and its hemolytic activity was greatly diminished compared to those of thehlyIIImutant and parent strains. In addition, thehlyBAmutant had a significant modification in colony morphology and growth deficiency compared to the parent strain. The implications of these findings for the pathophysiology ofB. fragilisin extraintestinal infections and competition in ecological systems for this organism are discussed.
ShiA Abrogates the Innate T-Cell Response toShigella flexneriInfection
Authors: Ingersoll Molly A. , Zychlinsky Arturo 
Published: March 2006

ABSTRACTShigellaspp. are the causative agent of bacillary dysentery. Infection results in acute colonic injury due to the host inflammatory response. The mediators of the damage, infiltrating polymorphonuclear leukocytes (PMN), also resolve the infection.Shigella flexneri's virulence effectors are encoded on its large virulence plasmid and on pathogenicity islands in the chromosome. The SHI-2 pathogenicity island encodes the virulence factor ShiA, which down-regulatesShigella-induced inflammation. In the rabbit ileal loop model, infection with ashiAnull strain (ΔshiA) induces a more severe inflammation than wild-type infection. Conversely, aShigellastrain that overexpresses ShiA (ShiA+) is less inflammatory than the wild-type strain. To determine the host responses modulated by ShiA, we performed infection studies using the mouse lung model, which recapitulates the phenotypes observed in the rabbit ileal loop model. Significantly, ShiA+strain-infected mice cleared the bacteria and survived infection, while wild-type- and ΔshiAstrain-infected mice could not clear the bacteria and ultimately died. Surprisingly, microarray analysis of infected lungs revealed the regulation of genes involved in innate T-cell responses to infection. Immunohistochemistry showed that wild-type- and ΔshiAstrain-infected animals have greater numbers of PMN and T cells in their lungs over the course of infection than ShiA+strain-infected animals. These results suggest that the T-cell innate response is suppressed by ShiA inShigellainfections.