bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunopathogenesis of Oropharyngeal Candidiasis in Human Immunodeficiency Virus Infection
Authors: de Repentigny Louis , Lewandowski Daniel , Jolicoeur Paul 
Published: October 2004

SUMMARYOropharyngeal and esophageal candidiases remain significant causes of morbidity in human immunodeficiency virus (HIV)-infected patients, despite the dramatic ability of antiretroviral therapy to reconstitute immunity. Notable advances have been achieved in understanding, at the molecular level, the relationships between the progression of HIV infection, the acquisition, maintenance, and clonality of oral candidal populations, and the emergence of antifungal resistance. However, the critical immunological defects which are responsible for the onset and maintenance of mucosal candidiasis in patients with HIV infection have not been elucidated. The devastating impact of HIV infection on mucosal Langerhans' cell and CD4+cell populations is most probably central to the pathogenesis of mucosal candidiasis in HIV-infected patients. However, these defects may be partly compensated by preserved host defense mechanisms (calprotectin, keratinocytes, CD8+T cells, and phagocytes) which, individually or together, may limit Candida albicans proliferation to the superficial mucosa. The availability of CD4C/HIV transgenic mice expressing HIV-1 in immune cells has provided the opportunity to devise a novel model of mucosal candidiasis that closely mimics the clinical and pathological features of candidal infection in human HIV infection. These transgenic mice allow, for the first time, a precise cause-and-effect analysis of the immunopathogenesis of mucosal candidiasis in HIV infection under controlled conditions in a small laboratory animal.
Treatment of Infections Caused by Metronidazole-ResistantTrichomonas vaginalis
Authors: Cudmore Sarah L. , Delgaty Kiera L. , Hayward-McClelland Shannon F. , Petrin Dino P. , Garber Gary E. 
Published: October 2004

SUMMARYInfections with the sexually transmitted protozoanTrichomonas vaginalisare usually treated with metronidazole, a 5-nitroimidazole drug derived from the antibiotic azomycin. Metronidazole treatment is generally efficient in eliminatingT. vaginalisinfection and has a low risk of serious side effects. However, studies have shown that at least 5% of clinical cases of trichomoniasis are caused by parasites resistant to the drug. The lack of approved alternative therapies forT. vaginalistreatment means that higher and sometimes toxic doses of metronidazole are the only option for patients with resistant disease. Clearly, studies of the treatment and prevention of refractory trichomoniasis are essential. This review describes the mechanisms of metronidazole resistance inT. vaginalisand provides a summary of trichomonicidal and vaccine candidate drugs.
Trichomoniasis
Authors: Schwebke Jane R. , Burgess Donald 
Published: October 2004

SUMMARYTrichomoniasis is perhaps the most common curable sexually transmitted disease worldwide, yet few resources are devoted to its control. It is associated with potentially serious complications such as preterm birth and human immunodeficiency virus acquisition and transmission. The immunology of a related organism, Tritrichomonas foetus, which causes disease in cattle, has been investigated to some extent, but more work is needed for the human strain, Trichomonas vaginalis. In addition, although trichomoniasis is easily treated with oral metronidazole, there is concern that the number of strains resistant to this antibiotic are increasing, and currently no alternative is licensed in the United States. As more is appreciated concerning the important public health implications of this common infection, more work will need to be done in understanding the diagnosis, treatment, and immunology of this organism.
Sarcocystis
spp. in Human Infections
Authors: Fayer Ronald 
Published: October 2004

SUMMARY

Sarcocystis
species are intracellular protozoan parasites with an intermediate-definitive host life cycle based on a prey-predator relationship. Asexual stages develop in intermediate hosts after they ingest the oocyst stage from definitive-host feces and terminate with the formation of intramuscular cysts (sarcocysts). Sarcocysts in meat eaten by a definitive host initiate sexual stages in the intestine that terminate in oocysts excreted in the feces. Most
Sarcocystis
species infect specific hosts or closely related host species. For example, humans and some primates are definitive hosts for
Sarcocystis hominis
and
S. suihominis
after eating raw meat from cattle and pigs, respectively. The prevalence of intestinal sarcocystosis in humans is low and is only rarely associated with illness, except in volunteers who ingest large numbers of sarcocysts. Cases of infection of humans as intermediate hosts, with intramuscular cysts, number less than 100 and are of unknown origin. The asexual stages, including sarcocysts, can stimulate a strong inflammatory response. Livestock have suffered acute debilitating infections, resulting in abortion and death or chronic infections with failure to grow or thrive. This review provides a summary of
Sarcocystis
biology, including its morphology, life cycle, host specificity, prevalence, diagnosis, treatment, and prevention strategies, for human and food animal infections.
The Molecular Mechanisms Used byNeisseria gonorrhoeaeTo Initiate Infection Differ between Men and Women
Authors: Edwards Jennifer L. , Apicella Michael A. 
Published: October 2004

SUMMARYThe molecular mechanisms used by the gonococcus to initiate infection exhibit gender specificity. The clinical presentations of disease are also strikingly different upon comparison of gonococcal urethritis to gonococcal cervicitis. An intimate association occurs between the gonococcus and the urethral epithelium and is mediated by the asialoglycoprotein receptor. Gonococcal interaction with the urethral epithelia cell triggers cytokine release, which promotes neutrophil influx and an inflammatory response. Similarly, gonococcal infection of the upper female genital tract also results in inflammation. Gonococci invade the nonciliated epithelia, and the ciliated cells are subjected to the cytotoxic effects of tumor necrosis factor alpha induced by gonococcal peptidoglycan and lipooligosaccharide. In contrast, gonococcal infection of the lower female genital tract is typically asymptomatic. This is in part the result of the ability of the gonococcus to subvert the alternative pathway of complement present in the lower female genital tract. Gonococcal engagement of complement receptor 3 on the cervical epithelia results in membrane ruffling and does not promote inflammation. A model of gonococcal pathogenesis is presented in the context of the male and female human urogenital tracts.
Diagnosis and Assessment of Trachoma
Authors: Solomon Anthony W. , Peeling Rosanna W. , Foster Allen , Mabey David C. W. 
Published: October 2004

SUMMARYTrachoma is caused byChlamydia trachomatis. Clinical grading with the WHO simplified system can be highly repeatable provided graders are adequately trained and standardized. At the community level, rapid assessments are useful for confirming the absence of trachoma but do not determine the magnitude of the problem in communities where trachoma is present. New rapid assessment protocols incorporating techniques for obtaining representative population samples (without census preparation) may give better estimates of the prevalence of clinical trachoma. Clinical findings do not necessarily indicate the presence or absence ofC. trachomatisinfection, particularly as disease prevalence falls. The prevalence of ocularC. trachomatisinfection (at the community level) is important because it is infection that is targeted when antibiotics are distributed in trachoma control campaigns. Methods to estimate infection prevalence are required. While culture is a sensitive test for the presence of viable organisms and nucleic acid amplification tests are sensitive and specific tools for the presence of chlamydial nucleic acids, the commercial assays presently available are all too expensive, too complex, or too unreliable for use in national programs. There is an urgent need for a rapid, reliable test forC. trachomatisto assist in measuring progress towards the elimination of trachoma.
Genome of Bacteriophage P1
Authors: Łobocka Małgorzata B. , Rose Debra J. , Plunkett Guy , Rusin Marek , Samojedny Arkadiusz , Lehnherr Hansjörg , Yarmolinsky Michael B. , Blattner Frederick R. 
Published: October 2004

ABSTRACTP1 is a bacteriophage ofEscherichia coliand other enteric bacteria. It lysogenizes its hosts as a circular, low-copy-number plasmid. We have determined the complete nucleotide sequences of two strains of a P1 thermoinducible mutant, P1c1-100. The P1 genome (93,601 bp) contains at least 117 genes, of which almost two-thirds had not been sequenced previously and 49 have no homologs in other organisms. Protein-coding genes occupy 92% of the genome and are organized in 45 operons, of which four are decisive for the choice between lysis and lysogeny. Four others ensure plasmid maintenance. The majority of the remaining 37 operons are involved in lytic development. Seventeen operons are transcribed from σ70promoters directly controlled by the master phage repressor C1. Late operons are transcribed from promoters recognized by theE. coliRNA polymerase holoenzyme in the presence of the Lpa protein, the product of a C1-controlled P1 gene. Three species of P1-encoded tRNAs provide differential controls of translation, and a P1-encoded DNA methyltransferase with putative bifunctionality influences transcription, replication, and DNA packaging. The genome is particularly rich in Chi recombinogenic sites. The base content and distribution in P1 DNA indicate that replication of P1 from its plasmid origin had more impact on the base compositional asymmetries of the P1 genome than replication from the lytic origin of replication.
Lactobacillus plantarum
Bacteriophage LP65: a New Member of the SPO1-Like Genus of the Family
Myoviridae
Authors: Chibani-Chennoufi Sandra , Dillmann Marie-Lise , Marvin-Guy Laure , Rami-Shojaei Sabrina , Brüssow Harald 
Published: October 2004

ABSTRACT

The virulent
Lactobacillus plantarum
myophage LP65 was isolated from industrial meat fermentation. Tail contraction led to reorganization of the tail sheath and the baseplate; a tail tube was extruded. In ultrathin section the phage adsorbed via its baseplate to the exterior of the cell, while the tail tube tunneled through the thick bacterial cell wall. Convoluted membrane structures were induced in the infected cell. Progeny phage was detected 100 min postinfection, and lysis occurred after extensive digestion of the cell wall. Sequence analysis revealed a genome of 131,573 bp of nonredundant DNA. Four major genome regions and a large tRNA gene cluster were observed. One module corresponded to DNA replication genes. Helicase/primase and two replication/recombination enzymes represented the only links to T4-like
Myoviridae
from gram-negative bacteria. Another module corresponded to the structural genes. Sequence relatedness identified links with
Listeria
phage A511,
Staphylococcus
phage K, and
Bacillus
phage SPO1. LP65 structural proteins were identified by two-dimensional proteome analysis and mass spectrometry. The putative tail sheath protein showed a shear-induced change in electrophoretic migration behavior. The genome organization of the structural module in LP65 resembled that of
Siphoviridae
from the lambda supergroup.
Multicopy Plasmids Affect Replisome Positioning inBacillus subtilis
Authors: Wang Jue D. , Rokop Megan E. , Barker Melanie M. , Hanson Nathaniel R. , Grossman Alan D. 
Published: October 2004

ABSTRACTThe DNA replication machinery, various regions of the chromosome, and some plasmids occupy characteristic subcellular positions in bacterial cells. We visualized the location of a multicopy plasmid, pHP13, in living cells ofBacillus subtilisusing an array oflacoperators and LacI-green fluorescent protein (GFP). In the majority of cells, plasmids appeared to be highly mobile and randomly distributed. In a small fraction of cells, there appeared to be clusters of plasmids located predominantly at or near a cell pole. We also monitored the effects of the presence of multicopy plasmids on the position of DNA polymerase using a fusion of a subunit of DNA polymerase to GFP. Many of the plasmid-containing cells had extra foci of the replisome, and these were often found at uncharacteristic locations in the cell. Some of the replisome foci were dynamic and highly mobile, similar to what was observed for the plasmid. In contrast, replisome foci in plasmid-free cells were relatively stationary. Our results indicate that inB. subtilis, plasmid-associated replisomes are recruited to the subcellular position of the plasmid. Extending this notion to the chromosome, we postulated that the subcellular position of the chromosomally associated replisome is established by the subcellular location oforiCat the time of initiation of replication.
Rgg Regulates Growth Phase-Dependent Expression of Proteins Associated with Secondary Metabolism and Stress inStreptococcus pyogenes
Authors: Chaussee Michelle A. , Callegari Eduardo A. , Chaussee Michael S. 
Published: October 2004

ABSTRACTThe transcriptional regulatory protein Rgg coordinates amino acid catabolism and virulence factor expression inStreptococcus pyogenes. We used a proteomic approach to compare cytoplasmic proteins isolated fromS. pyogeneswild-type strain NZ131 (serotype M49) to proteins isolated from anrggmutant strain during the exponential and stationary phases of growth. Proteins were separated by two-dimensional gel electrophoresis, and 125 protein spots of interest were identified by tandem mass spectrometry. Comparative analysis of proteins isolated from the isogenic strains revealed that growth phase-associated regulation of enzymes involved in the metabolism of arginine (ArcABC), histidine (HutI), and serine (SdhA) was abrogated in therggmutant strain, which synthesized the proteins in the exponential phase of growth. In contrast, the enzymes were detected only among wild-type proteins isolated from organisms in the stationary phase of growth. The differences in protein composition were correlated with previously described metabolic changes. In addition, proteins associated with thermal and oxidative stress responses, including ClpE and ClpL, were present in samples isolated from therggmutant strain but not in samples isolated from the wild-type strain. Therggmutant strain was more tolerant to elevated temperature and puromycin than the wild-type strain; however, the mutant was less tolerant to paraquat. We concluded that Rgg is a global regulatory factor that contributes to growth phase-dependent synthesis of proteins associated with secondary metabolism and oxidative and thermal stress responses.
Four Proteins Encoded in the
gspB-secY2A2
Operon of
Streptococcus gordonii
Mediate the Intracellular Glycosylation of the Platelet-Binding Protein GspB
Authors: Takamatsu Daisuke , Bensing Barbara A. , Sullam Paul M. 
Published: October 2004

ABSTRACT

Platelet binding by
Streptococcus gordonii
strain M99 is mediated predominantly by the cell surface glycoprotein GspB. This adhesin consists of a putative N-terminal signal peptide, two serine-rich regions (SRR1 and SRR2), a basic region between SRR1 and SRR2, and a C-terminal cell wall anchoring domain. The glycosylation of GspB is mediated at least in part by Gly and Nss, which are encoded in the
secY2A2
locus immediately downstream of
gspB
. This region also encodes two proteins (Gtf and Orf4) that are required for the expression of GspB but whose functions have not been delineated. In this study, we further characterized the roles of Gly, Nss, Gtf, and Orf4 by investigating the expression and glycosylation of a series of glutathione
S
-transferase-GspB fusion proteins in M99 and in
gly
,
nss
,
gtf
, and
orf4
mutants. Compared with fusion proteins expressed in the wild-type background, fusion proteins expressed in the mutant strain backgrounds showed altered electrophoretic mobility. In addition, the fusion proteins formed insoluble aggregates in protoplasts of the
gtf
and
orf4
mutants. Glycan detection and lectin blot analysis revealed that SRR1 and SRR2 were glycosylated but that the basic region was unmodified. When the fusion protein was expressed in
Escherichia coli
, glycosylation of this protein was observed only in the presence of both
gtf
and
orf4
. These results demonstrate that Gly, Nss, Gtf, and Orf4 are all involved in the intracellular glycosylation of SRRs. Moreover, Gtf and Orf4 are essential for glycosylation, which in turn is important for the solubility of GspB.
Classification and Strength Measurement of Stationary-Phase Promoters by Use of a Newly Developed Promoter Cloning Vector
Authors: Shimada Tomohiro , Makinoshima Hideki , Ogawa Yoshito , Miki Takeyoshi , Maeda Michihisa , Ishihama Akira 
Published: October 2004

ABSTRACT

When
an
Escherichia coli
culture changes from exponential growth to
the stationary phase, expression of growth-related genes levels off,
while a number of stationary-phase-specific genes are turned on. To
gain insight into the growth phase-dependent global regulation of
genome transcription, we analyzed the strength and specificity of
promoters associated with the stationary-phase genes. For the in vivo
assay of promoter activity, 300- to 500-bp DNA fragments upstream from
the translation initiation codon were isolated and inserted into a
newly constructed doubly fluorescent protein (DFP) vector. The activity
of test promoters was determined by measuring the green fluorescent
protein (GFP). To avoid the possible influence of plasmid copy number,
the level of transcription of reference promoter
lac
UV5 on the same plasmid was determined by
measuring the red fluorescent protein (RFP). Thus, the activities of
test promoters could be easily and accurately determined by determining
the GFP/RFP ratio. Analysis of the culture time-dependent variation of
100 test promoters indicated that (i) a major group of the
stationary-phase promoters are up-regulated only in the presence of
RpoS sigma; (ii) the phase-coupled increase in the activity of some
promoters takes place even in the absence of RpoS; and (iii) the
activity of some promoters increases in the absence of RpoS. This
classification was confirmed by testing in vitro transcription by using
reconstituted RpoD and RpoS
holoenzymes.
Isolation of SOS Constitutive Mutants ofEscherichia coli
Authors: O'Reilly Erin K. , Kreuzer Kenneth N. 
Published: October 2004

ABSTRACTThe bacterial SOS regulon is strongly induced in response to DNA damage from exogenous agents such as UV radiation and nalidixic acid. However, certain mutants with defects in DNA replication, recombination, or repair exhibit a partially constitutive SOS response. These mutants presumably suffer frequent replication fork failure, or perhaps they have difficulty rescuing forks that failed due to endogenous sources of DNA damage. In an effort to understand more clearly the endogenous sources of DNA damage and the nature of replication fork failure and rescue, we undertook a systematic screen forEscherichia colimutants that constitutively express the SOS regulon. We identified mutant strains with transposon insertions in 42 genes that caused increased expression from adinD1::lacZreporter construct. Most of these also displayed significant increases in basal levels of RecA protein, confirming an effect on the SOS system. As expected, this collection includes genes, such aslexA, dam,rep,xerCD,recG, andpolA, which have previously been shown to cause an SOS constitutive phenotype when inactivated. The collection also includes 28 genes or open reading frames that were not previously identified as SOS constitutive, includingdcd, ftsE, ftsX, purF,tdcE, andtynA. Further study of these SOS constitutive mutants should be useful in understanding the multiple causes of endogenous DNA damage. This study also provides a quantitative comparison of the extent of SOS expression caused by inactivation of many different genes in a common genetic background.
The N Terminus of MinD Contains Determinants Which Affect Its Dynamic Localization and Enzymatic Activity
Authors: Szeto Jason , Acharya Sudeep , Eng Nelson F. , Dillon Jo-Anne R. 
Published: October 2004

ABSTRACT

MinD is involved in regulating the proper placement of the cytokinetic machinery in some bacteria, including
Neisseria gonorrhoeae
and
Escherichia coli
. Stimulation of the ATPase activity of MinD by MinE has been proposed to induce dynamic, pole-to-pole oscillations of MinD in
E. coli
. Here, we investigated the effects of deleting or mutating conserved residues within the N terminus of
N. gonorrhoeae
MinD (MinD
Ng
) on protein dynamism, localization, and interactions with MinD
Ng
and with MinE
Ng
. Deletions or mutations were generated in the first five residues of MinD
Ng
, and mutant proteins were evaluated by several functional assays. Truncation or mutation of N-terminal residues disrupted MinD
Ng
interactions with itself and with MinE. Although the majority of green fluorescent protein (GFP)-MinD
Ng
mutants could still oscillate from pole to pole in
E. coli
, the GFP-MinD
Ng
oscillation cycles were significantly faster and were accompanied by increased cytoplasmic localization. Interestingly, in vitro ATPase assays indicated that MinD
Ng
proteins lacking the first three residues or with an I5E substitution possessed higher MinE
Ng
-independent ATPase activities than the wild-type protein. These results indicate that determinants found within the extreme N terminus of MinD
Ng
are implicated in regulating the enzymatic activity and dynamic localization of the protein.
σ
S
-Dependent Gene Expression at the Onset of Stationary Phase in
Escherichia coli
: Function of σ
S
-Dependent Genes and Identification of Their Promoter Sequences
Authors: Lacour Stephan , Landini Paolo 
Published: October 2004

ABSTRACT

The σ
S
subunit of RNA polymerase, the product of the
rpoS
gene, controls the expression of genes responding to starvation and cellular stresses. Using gene array technology, we investigated
rpoS
-dependent expression at the onset of stationary phase in
Escherichia coli
grown in rich medium. Forty-one genes were expressed at significantly lower levels in an
rpoS
mutant derived from the MG1655 strain; for 10 of these, we also confirmed
rpoS
and stationary-phase dependence by reverse transcription-PCR. Only seven genes (
dps
,
osmE
,
osmY
,
sodC
,
rpsV
,
wrbA
, and
yahO
) had previously been recognized as
rpoS
dependent. Several newly identified
rpoS
-dependent genes are involved in the uptake and metabolism of amino acids, sugars, and iron. Indeed, the
rpoS
mutant strain shows severely impaired growth on some sugars such as fructose and
N
-acetylglucosamine. The
rpoS
gene controls the production of indole, which acts as a signal molecule in stationary-phase cells, via regulation of the
tnaA
-encoded tryptophanase enzyme. Genes involved in protein biosynthesis, encoding the ribosome-associated protein RpsV (
sra
) and the initiation factor IF-1 (
infA
), were also induced in an
rpoS
-dependent fashion. Using primer extension, we determined the promoter sequences of a selection of
rpoS
-regulated genes representative of different functional classes. Significant fractions of these promoters carry sequence features specific for Eσ
S
recognition of the −10 region, such as cytosines at positions −13 (70%) and −12 (30%) as well as a TG motif located upstream of the −10 region (50%), thus supporting the TGN
0-2
C(C/T)ATA(C/A)T consensus sequence recently proposed for σ
S
.