bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increasing the Pleasure and Enjoyment of Exercise: A Novel Resistance-Training Protocol
Authors: Hutchinson Jasmin C. , Zenko Zachary , Santich Sam , Dalton Paul C. 
Published: March 2020

This study was designed to test the effect of an increasing- (UP) or decreasing-intensity (DOWN) resistance-training (RT) protocol on the pleasure and enjoyment of RT. The participants (N = 40; mean age = 35.0 ± 9.2 years) completed two RT sessions comprising 3 × 10 repetitions of six exercises. In the UP condition, load progressively increased from 55% to 75% of 1-repetition maximum, while in the DOWN condition, this pattern was reversed (i.e., 75–55% 1-repetition maximum). The DOWN condition resulted in more overall pleasure compared with UP and a slope of increasing pleasure, while the UP condition resulted in decreasing pleasure. Enjoyment of RT, postexercise pleasure, and remembered pleasure were all significantly greater for DOWN compared with UP (allps > .01). These findings suggest that decreasing RT intensity throughout an exercise bout can elicit a positive slope of pleasure and enhance affective evaluations of exercise.
Vibrio cholerae
Hemagglutinin/Protease Inactivates CTXφ
Authors: Kimsey Harvey H. , Waldor Matthew K. 
Published: March 2020

ABSTRACT

Pathogenic strains of
Vibrio cholerae
are lysogens of the filamentous phage CTXφ, which carries the genes for cholera toxin (
ctxAB
). We found that the titers of infective CTXφ in culture supernatants of El Tor CTXφ lysogens increased rapidly during exponential growth but dropped to undetectable levels late in stationary-phase growth. When CTXφ transducing particles were mixed with stationary-phase culture supernatants of El Tor strains, CTXφ infectivity was destroyed. Our data indicate that this growth phase-regulated factor, designated CDF (CTXφ-destroying factor), is the secreted hemagglutinin/protease (HA/P) of
V. cholerae
. A strain containing a disrupted
hap
gene, which encodes HA/P of
V. cholerae
, did not produce CDF activity in culture supernatants. Introduction of the HA/P-expressing plasmid pCH2 restored CDF activity. Also, CDF activity in culture supernatants of a variety of pathogenic
V. cholerae
isolates varied widely but correlated with the levels of secreted HA/P, as measured by immunoblotting with anti-HA/P antibody. CDF was purified from
V. cholerae
culture supernatants and shown to contain a 45-kDa polypeptide which bound anti-HA/P antibodies and which comigrated with HA/P in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The production of high levels of secreted HA/P by certain
V. cholerae
strains may be a factor in preventing CTXφ reinfection in natural environments and in the human host.
The Contributions of Reactive Oxygen Intermediates and Reactive Nitrogen Intermediates to Listericidal Mechanisms Differ in Macrophages Activated Pre- and Postinfection
Authors: Ohya Satoshi , Tanabe Yoshinari , Makino Masato , Nomura Takamasa , Xiong Huabao , Arakawa Masaaki , Mitsuyama Masao 
Published: March 2020

ABSTRACTThe contribution of reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI) to the killing ofListeria monocytogenesby macrophages activated by addition of spleen cells from listeria-immune mice plus specific antigen was examined. When macrophages were infected withL. monocytogenesand then spleen cells were added, there was not as big a difference in listericidal activity between macrophages cultured with normal spleen cells and those cultured with immune spleen cells as expected. In this culture system, RNI was mainly involved in the macrophage intracellular killing. In macrophages first activated and then infected, a significant level of enhanced killing was observed. Blockade of ROI production drastically affected the enhanced killing ability, while inhibition of RNI production had a negligible effect. Thus, the contributions of ROI and RNI to listericidal mechanisms of macrophages were different between macrophages activated at pre- and postinfection stages.
Lyme Disease-Causing
Borrelia
Species Encode Multiple Lipoproteins Homologous to Peptide-Binding Proteins of ABC-Type Transporters
Authors: Kornacki Jon A. , Oliver Donald B. 
Published: March 2020

ABSTRACT

To identify cell envelope proteins of Borrelia burgdorferi, the causative agent of Lyme disease, we constructed a library of
B. burgdorferi
genes fused to the Escherichia coli phoA gene, which expresses enzymatically active alkaline phosphatase. One such gene, oppA-1, encodes a predicted polypeptide with significant similarities to various peptide-binding proteins of ABC-type transporters. Immediately downstream of oppA-1 are two genes, oppA-2 and oppA-3, whose predicted polypeptide products show strong similarities in their amino acid sequences to OppA-1, including a sequence that resembles the most highly conserved region in peptide-binding proteins. By labeling with [
3
H]palmitate, OppA-1, OppA-2, and OppA-3 were shown to be lipoproteins. DNA hybridization analysis showed that the oppA-1 oppA-2 oppA-3 region is located on the linear chromosome of
B. burgdorferi
, and the genes are conserved among different Borrelia species that cause Lyme disease (
B. burgdorferi
, B. garinii, and B. afzelli), suggesting that all three homologous genes are important to the maintenance of Lyme disease spirochetes in one or more of their hosts.
SirR, a Novel Iron-Dependent Repressor in
Staphylococcus epidermidis
Authors: Hill Philip J. , Cockayne Alan , Landers Patrick , Morrissey Julie A. , Sims Catriona M. , Williams Paul 
Published: March 2020

ABSTRACT

In
Staphylococcus epidermidis
and
Staphylococcus aureus
, a number of cell wall- and cytoplasmic membrane-associated lipoproteins are induced in response to iron starvation. To gain insights into the molecular basis of iron-dependent gene regulation in the staphylococci, we sequenced the DNA upstream of the 3-kb
S. epidermidis sitABC
operon, which Northern blot analysis indicates is transcriptionally regulated by the growth medium iron content. We identified two DNA sequences which are homologous to elements of the
Corynebacterium diphtheriae
DtxR regulon, which controls, in response to iron stress, for example, production of diphtheria toxin, siderophore, and a heme oxygenase. Upstream of the
sitABC
operon and divergently transcribed lies a 645-bp open reading frame (ORF), which codes for a polypeptide of approximately 25 kDa with homology to the DtxR family of metal-dependent repressor proteins. This ORF has been designated SirR (staphylococcal iron regulator repressor). Within the
sitABC
promoter/operator region, we also located a region of dyad symmetry overlapping the transcriptional start of
sitABC
which shows high homology to the DtxR operator consensus sequence, suggesting that this region, termed the Sir box, is the SirR-binding site. The SirR protein was overexpressed, purified, and used in DNA mobility shift assays; SirR retarded the migration of a synthetic oligonucleotide based on the Sir box in a metal (Fe
2+
or Mn
2+
)-dependent manner, providing confirmatory evidence that this motif is the SirR-binding site. Furthermore, Southern blot analysis of staphylococcal chromosomal DNA with the synthetic Sir box as a probe confirmed that there are at least five Sir boxes in the
S. epidermidis
genome and at least three in the genome of
S. aureus
, suggesting that SirR controls the expression of multiple target genes. Using a monospecific polyclonal antibody raised against SirR to probe Western blots of whole-cell lysates of
S. aureus
,
S. carnosus
,
S. epidermidis
,
S. hominis
,
S. cohnii
,
S. lugdunensis
, and
S. haemolyticus
, we identified an approximately 25-kDa cross-reactive protein in each of the staphylococcal species examined. Taken together, these data suggest that SirR functions as a divalent metal cation-dependent transcriptional repressor which is widespread among the staphylococci.
Bone Resorption Caused by Three Periodontal Pathogens In Vivo in Mice Is Mediated in Part by Prostaglandin
Authors: Zubery Yuval , Dunstan Colin R. , Story Beryl M. , Kesavalu Lakshmyya , Ebersole Jeffrey L. , Holt Stanley C. , Boyce Brendan F. 
Published: March 2020

ABSTRACT

Gingival inflammation, bacterial infection, alveolar bone destruction, and subsequent tooth loss are characteristic features of periodontal disease, but the precise mechanisms of bone loss are poorly understood. Most animal models of the disease require injury to gingival tissues or teeth, and the effects of microorganisms are thus complicated by host responses to tissue destruction. To determine whether three putative periodontal pathogens,
Porphyromonas gingivalis
,
Campylobacter rectus
, and
Fusobacterium nucleatum
, could cause localized bone resorption in vivo in the absence of tissue injury, we injected live or heat-killed preparations of these microorganisms into the subcutaneous tissues overlying the calvaria of normal mice once daily for 6 days and then examined the bones histologically. We found that all three microorganisms (both live and heat killed) stimulated bone resorption and that the strain of
F. nucleatum
used appeared to be the strongest inducer of osteoclast activity. Treatment of the mice concomitantly with indomethacin reduced but did not completely inhibit bone resorption by these microorganisms, suggesting that their effects were mediated, in part, by arachidonic acid metabolites (e.g., prostaglandins). Our findings indicate that these potential pathogens can stimulate bone resorption locally when placed beside a bone surface in vivo in the absence of prior tissue injury and support a role for them in the pathogenesis of bone loss around teeth in periodontitis.
Effectiveness of Liposomes Possessing Surface-Linked Recombinant B Subunit of Cholera Toxin as an Oral Antigen Delivery System
Authors: Harokopakis Evlambia , Hajishengallis George , Michalek Suzanne M. 
Published: March 2020

ABSTRACTLiposomes appear to be a promising oral antigen delivery system for the development of vaccines against infectious diseases, although their uptake efficiency by Peyer’s patches in the gut and the subsequent induction of mucosal immunoglobulin A (IgA) responses remain a major concern. Aiming at targeted delivery of liposomal immunogens, we have previously reported the conjugation via a thioether bond of the GM1ganglioside-binding subunit of cholera toxin (CTB) to the liposomal outer surface. In the present study, we have investigated the effectiveness of liposomes containing the saliva-binding region (SBR) ofStreptococcus mutansAgI/II adhesin and possessing surface-linked recombinant CTB (rCTB) in generating mucosal (salivary, vaginal, and intestinal) IgA as well as serum IgG responses to the parent molecule, AgI/II. Responses in mice given a single oral dose of the rCTB-conjugated liposomes were compared to those in mice given one of the following unconjugated liposome preparations: (i) empty liposomes, (ii) liposomes containing SBR, (iii) liposomes containing SBR and coadministered with rCTB, and (iv) liposomes containing SBR plus rCTB. Three weeks after the primary immunization, significantly higher levels of mucosal IgA and serum IgG antibodies to AgI/II were observed in the rCTB-conjugated group than in mice given the unconjugated liposome preparations, although the latter mice received a booster dose at week 9. The antibody responses in mice immunized with rCTB-conjugated liposomes persisted at high levels for at least 6 months, at which time (week 26) a recall immunization significantly augmented the responses. In general, mice given unconjugated liposome preparations required one or two booster immunizations to develop a substantial anti-AgI/II antibody response, which was more prominent in the group given coencapsulated SBR and rCTB. These data indicate that conjugation of rCTB to liposomes greatly enhances their effectiveness as an antigen delivery system. This oral immunization strategy should be applicable for the development of vaccines against oral, intestinal, or sexually transmitted diseases.
A Cluster of Genes Involved in Polysaccharide Biosynthesis from
Enterococcus faecalis
OG1RF
Authors: Xu Yi , Murray Barbara E. , Weinstock George M. 
Published: March 2020

ABSTRACT

Our previous work identified a cosmid clone containing a 43-kb insert from
Enterococcus faecalis
OG1RF that produced a nonprotein antigen in
Escherichia coli
. In the present work, we studied this clone in detail. Periodate treatment of lysates of the clone confirmed that the antigen was carbohydrate in nature. Analysis of DNA sequences and transposon insertion mutants suggested that the insert contained a multicistronic gene cluster. Database comparison showed that the cluster contained genes similar to genes involved in the biosynthesis of dTDP-rhamnose, glycosyltransferases, and ABC transporters involved in the export of sugar polymers from both gram-positive and gram-negative organisms. Insertions in several genes within the cluster abolished the immunoreactivity of the clone. This is the first report on a gene cluster of
E. faecalis
involved in the biosynthesis of an antigenic polysaccharide.
Immunization against NaturalHelicobacter pyloriInfection in Nonhuman Primates
Authors: Dubois Andre , Lee Cynthia K. , Fiala Nancy , Kleanthous Harry , Mehlman Patrick T. , Monath Thomas 
Published: March 2020

ABSTRACTHelicobacter pyloriinfection is widespread in some breeding groups of a rhesus monkey colony (71%H. pyloripositive by 1 year), and the rate of seroconversion is also high. As a result, these groups can be used to test the safety and efficacy of an anti-H. pylorivaccine. Nine-month-old female animals were randomized to receive either 8 mg of recombinant urease (rUre) plus 25 μg ofEscherichia coliheat-labile enterotoxin (LT) (n= 26) or placebo plus LT (n= 29), given four times at 1-week intervals followed by a booster 1 month later. Ten months after the start of the immunization, the animals were subjected to endoscopy and biopsy samples were obtained.H. pylorinegativity was defined as noH. pylorigrowth by culture and noH. pyloriobserved at histology. By this criterion, 2 (7%) of 29 animals receiving placebo and 8 (31%) of 26 immunized animals wereH. pylorinegative (P< 0.035). In addition, antral gastritis score was significantly less inH. pylori-negative immunized monkeys than inH. pylori-positive animals, whether they were given rUre plus LT or placebo plus LT (P< 0.02 orP< 0.01, respectively). Interestingly, antral gastritis was also significantly less inH. pylori-positive animals given rUre plus LT than inH. pylori-positive animals given placebo plus LT (P< 0.02). However, quantitative cultures did not demonstrate significant differences between the two latter groups. It is concluded that oral administration of rUre vaccine plus LT significantly protects nonhuman primates againstH. pyloriinfection while not causing undesirable side effects.
Deletion of Repeats in the Alpha C Protein Enhances the Pathogenicity of Group B Streptococci in Immune Mice
Authors: Gravekamp C. , Rosner Bernard , Madoff L. C. 
Published: March 2020

ABSTRACT

The alpha C protein is a protective surface-associated antigen of group B streptococci (GBS). The prototype alpha C protein of GBS (strain A909) contains nine identical tandem repeats, each comprising 82 amino acids, flanked by N- and C-terminal domains. Clinical isolates of GBS show variable numbers of repeats with a normal distribution and a median of 9 to 10 repeats. Here, we show that escape mutants of GBS expressing one-repeat alpha C protein were 100-fold more pathogenic than GBS expressing wild-type nine-repeat alpha C protein in neonatal mice whose dams were immunized with antiserum elicited to nine-repeat alpha C protein (50% lethal doses of 1.6 × 10
3
and 1.8 × 10
5
, respectively;
P
= 0.0073). There was no difference in pathogenicity in nonimmune mice. Enzyme-linked immunosorbent assay inhibition showed that nine-repeat but not one-repeat alpha C protein is readily available for antibody binding on the surface of intact GBS. Immune electron microscopy studies with antibodies to the capsular polysaccharide (CPS) and to the alpha C protein demonstrated localization of the nine-repeat alpha C protein and the CPS at similar distances from the cell wall. The one-repeat alpha C protein was visualized poorly and only in close proximity to the cell wall, thus suggesting that antibody binding to the protein was hindered by CPS or other cell surface components. We concluded that deletion in the repeat region of the alpha C protein enhanced the pathogenicity of GBS in immune mice by (i) loss of a protective (conformational) epitope(s) and (ii) loss of antibody binding to the alpha C protein due to a decrease in antigen size relative to cell wall components and/or CPS.
Isolation and Characterization of Two Proteins fromMoraxella catarrhalisThat Bear a Common Epitope
Authors: McMichael John C. , Fiske Michael J. , Fredenburg Ross A. , Chakravarti Deb N. , VanDerMeid Karl R. , Barniak Vicki , Caplan Jeffrey , Bortell Eric , Baker Steven , Arumugham Rasappa , Chen Dexiang 
Published: March 2020

ABSTRACTThe UspA1 and UspA2 proteins ofMoraxella catarrhalisare potential vaccine candidates for preventing disease caused by this organism. We have characterized both proteins and evaluated their vaccine potential using both in vitro and in vivo assays. Both proteins were purified from the O35E isolate by Triton X-100 extraction, followed by ion-exchange and hydroxyapatite chromatography. Analysis of the sequences of internal peptides, prepared by enzymatic and chemical cleavage of the proteins, revealed that UspA1 and UspA2 exhibited distinct structural differences but shared a common sequence including an epitope recognized by the monoclonal antibody 17C7. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), purified UspA1 exhibited a molecular weight of approximately 350,000 when unheated and a molecular weight of 100,000 after being heated for 10 min at 100°C. In contrast, purified UspA2 exhibited an apparent molecular weight of 240,000 by SDS-PAGE that did not change with the length of time of heating. Their sizes as determined by gel filtration were 1,150,000 and 830,000 for UspA1 and UspA2, respectively. Preliminary results indicate the proteins have separate functions in bacterial pathogenesis. Purified UspA1 was found to bind HEp-2 cells, and sera against UspA1, but not against UspA2, blocked binding of the O35E isolate to the HEp-2 cells. UspA1 also bound fibronectin and appears to have a role in bacterial attachment. Purified UspA2, however, did not bind fibronectin but had an affinity for vitronectin. Both proteins elicited bactericidal antibodies in mice to homologous and heterologous disease isolates. Finally, mice immunized with each of the proteins, followed by pulmonary challenge with either the homologous or a heterologous isolate, cleared the bacteria more rapidly than mock-immunized mice. These results suggest that UspA1 and UspA2 serve different virulence functions and that both are promising vaccine candidates.
Actinomyces naeslundii
Displays Variant
fimP
and
fimA
Fimbrial Subunit Genes Corresponding to Different Types of Acidic Proline-Rich Protein and β-Linked Galactosamine Binding Specificity
Authors: Hallberg K. , Holm C. , Öhman U. , Strömberg N. 
Published: March 2020

ABSTRACT

Actinomyces naeslundii
genospecies 1 and 2 bind to acidic proline-rich proteins (APRPs) and statherin via type 1 fimbriae and to β-linked galactosamine (GalNAcβ) structures via type 2 fimbriae. In addition,
A. naeslundii
displays two types of binding specificity for both APRPs-statherin and GalNAcβ, while
Actinomyces odontolyticus
binds to unknown structures. To study the molecular basis for these binding specificities, DNA fragments spanning the entire or central portions of
fimP
(type 1) and
fimA
(type 2) fimbrial subunit genes were amplified by PCR from strains of genospecies 1 and 2 and hybridized with DNA from two independent collections of oral
Actinomyces
isolates. Isolates of genospecies 1 and 2 and
A. odontolyticus
, but no other
Actinomyces
species, were positive for hybridization with
fimP
and
fimA
full-length probes irrespective of binding to APRPs and statherin, GalNAcβ, or unknown structures. Isolates of genospecies 1 and 2, with deviating patterns of GalNAcβ1-3Galα-
O
-ethyl-inhibitable coaggregation with
Streptococcus oralis
Ss34 and MPB1, were distinguished by a
fimA
central probe from genospecies 1 and 2, respectively. Furthermore, isolates of genospecies 1 and 2 displaying preferential binding to APRPs over statherin were positive with a
fimP
central probe, while a genospecies 2 strain with the opposite binding preference was not. The sequences of
fimP
and
fimA
central gene segments were highly conserved among isolates with the same, but diversified between those with a variant, binding specificity. In conclusion,
A. naeslundii
exhibits variant
fimP
and
fimA
genes corresponding to diverse APRP and GalNAcβ specificities, respectively, while
A. odontolyticus
has a genetically related but distinct adhesin binding specificity.
CD86 (B7-2), but Not CD80 (B7-1), Expression in the Epidermis of Transgenic Mice Enhances the Immunogenicity of Primary CutaneousCandida albicansInfections
Authors: Gaspari Anthony A. , Burns Robert , Nasir Adnan , Ramirez Diana , Barth Richard K. , Haidaris Constantine G. 
Published: March 2020

ABSTRACTTransgenic (Tg) mice whose epidermal keratinocytes constitutively overexpress either B7-1 (CD80) or B7-2 (CD86) exhibited exaggerated cutaneous delayed type hypersensitivity (DTH) to haptens compared to non-Tg mice. To determine whether enhanced DTH in these Tg mice is seen in response to cutaneous fungal infections, a primary infection withCandida albicanswas established by inoculating this organism on the occluded skin of Tg and non-Tg mice. These infections resolved 7 days after removal of occlusive dressing in all three groups of mice, without evidence of exaggerated inflammation in either the Tg or non-Tg mice. Only B7-2 Tg mice developed enhanced Th1-lymphocyte-mediated immune responses toC. albicansantigens after resolving this infection: enhanced footpad swelling in response to intradermalC. albicansantigens, enhanced production of mRNA encoding Th1 lymphokines in draining lymph nodes, and increased gamma interferon secreted into culture supernatants by lymph node T lymphocytes stimulated withCandidaantigens in vitro. Lastly, Western blotting of sera from mice that had resolved this fungal infection indicated that only B7-2 Tg mice recognized a wide range ofCandida-associated antigens. These data suggest that these two costimulatory molecules, when expressed by keratinocytes, do not deliver identical signals toC. albicansantigen-reactive Th1 lymphocytes. The enhanced immune response in B7-2 Tg mice to a cutaneousC. albicansinfection demonstrates the importance of antigen presentation and costimulation in immune reactivity to fungi. Furthermore, B7-2 Tg mice may be useful in identification of protectiveCandidaantigens.
Binding of Heme-Hemopexin Complexes by Soluble HxuA Protein Allows Utilization of This Complexed Heme by
Haemophilus influenzae
Authors: Cope Leslie D. , Thomas Sharon E. , Hrkal Zbynek , Hansen Eric J. 
Published: March 2020

ABSTRACT

Utilization of heme-hemopexin as a source of heme by
Haemophilus influenzae
type b is dependent on expression by this bacterium of the 100-kDa HxuA protein, which is both present on the bacterial cell surface and released into the culture supernatant (L. D. Cope, R. Yogev, U. Muller-Eberhard, and E. J. Hansen, J. Bacteriol. 177:2644–2653, 1995). Radioimmunoprecipitation analysis showed that the soluble HxuA protein present in
H. influenzae
type b culture supernatant bound heme-hemopexin complexes in solution. An isogenic
H. influenzae
type b
hxuA
mutant was unable to utilize soluble heme-hemopexin complexes for growth in vitro unless soluble HxuA protein was provided exogenously. Soluble HxuA protein secreted by a nontypeable
H. influenzae
strain also allowed growth of this
H. influenzae
type b
hxuA
mutant. These results indicated that the heme present in heme-hemopexin complexes is rendered accessible to
H. influenzae
when these complexes are bound by the soluble HxuA protein.