bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microheterogeneity in 16S Ribosomal DNA-Defined Bacterial Populations from a Stratified Planktonic Environment Is Related to Temporal Changes and to Ecological Adaptations
Authors: Casamayor Emilio O. , Pedrós-Alió Carlos , Muyzer Gerard , Amann Rudolf 
Published: July 2002

ABSTRACT

Temporal changes of the bacterioplankton from a meromictic lake (Lake Vilar, Banyoles, Spain) were analyzed with four culture-independent techniques: epifluorescence microscopy, PCR-denaturing gradient gel electrophoresis (DGGE) fingerprinting, fluorescence in situ whole-cell hybridization and flow cytometry sorting. Microscopically, blooms of one cyanobacterium (
Synechococcus
sp.-like), one green sulfur bacterium (
Chlorobium phaeobacteroides
-like), and one purple sulfur bacterium (
Thiocystis minor
-like) were observed at different depths and times. DGGE retrieved these populations and, additionally, populations related to the
Cytophaga
-
Flavobacterium-Bacteroides
phylum as predominant community members. The analyses of partial 16S ribosomal DNA sequences from the DGGE fingerprints (550 bp analyzed) revealed higher genetic diversity than expected from microscopic observation for most of these groups. Thus, the sequences of two
Synechococcus
spp. (both had a similarity of 97% to
Synechococcus
sp. strain PCC6307 in 16S rRNA), two
Thiocystis
spp. (similarities to
Thiocystis minor
of 93 and 94%, respectively), and three
Cytophaga
spp. (similarities to
Cytophaga fermentans
of 88 and 89% and to
Cytophaga
sp. of 93%, respectively) were obtained. The two populations of
Synechococcus
exhibited different pigment compositions and temporal distributions and their 16S rRNA sequences were 97.3% similar. The two
Thiocystis
populations differed neither in pigment composition nor in morphology, but their 16S rRNA sequences were only 92.3% similar and they also showed different distributions over time. Finally, two of the
Cytophaga
spp. showed 96.2% similarity between the 16S rRNA sequences, but one of them was found to be mostly attached to particles and only in winter. Thus, the identity of the main populations changed over time, but the function of the microbial guilds was maintained. Our data showed that temporal shifts in the identity of the predominant population is a new explanation for the environmental 16S rRNA microdiversity retrieved from microbial assemblages and support the hypothesis that clusters of closely related 16S rRNA environmental sequences may actually represent numerous closely related, yet ecologically distinct, populations.
Cyanophycin Production in a Phycoerythrin-Containing Marine
Synechococcus
Strain of Unusual Phylogenetic Affinity
Authors: Wingard Lauren L. , Miller Scott R. , Sellker Jeanne M. L. , Stenn Erik , Allen Mary M. , Wood A. Michelle 
Published: July 2002

ABSTRACT

Thirty-two strains of phycoerythrin-containing marine picocyanobacteria were screened for the capacity to produce cyanophycin, a nitrogen storage compound synthesized by some, but not all, cyanobacteria. We found that one of these strains,
Synechococcus
sp. strain G2.1 from the Arabian Sea, was able to synthesize cyanophycin. The cyanophycin extracted from the cells was composed of roughly equimolar amounts of arginine and aspartate (29 and 35 mol%, respectively), as well as a small amount of glutamate (15 mol%). Phylogenetic analysis, based on partial 16S ribosomal DNA (rDNA) sequence data, showed that
Synechococcus
sp. strain G2.1 formed a well-supported clade with several strains of filamentous cyanobacteria. It was not closely related to several other well-studied marine picocyanobacteria, including
Synechococcus
strains PCC7002, WH7805, and WH8018 and
Prochlorococcus
sp. strain MIT9312. This is the first report of cyanophycin production in a phycoerythrin-containing strain of marine or halotolerant
Synechococcus
, and its discovery highlights the diversity of this ecologically important functional group.
Angiotensin II Increases Host Resistance to Peritonitis
Authors: Rodgers Kathleen , Xiong Shiquan , Espinoza Theresa , Roda Norma , Maldonado Sonia , diZerega Gere S. 
Published: July 2002

ABSTRACTStudies by other laboratories have shown that angiotensin II (AII) can affect the function of cells which comprise the immune system. In the present study, the effect of AII on the function of peritoneal macrophages and peripheral blood monocytes was assessed. In vitro exposure (4 h prior to assay) of peritoneal macrophages from mice and rats to AII increased the percentage of cells that phagocytosed opsonized yeast and the number of yeast per macrophage. Furthermore, AII increased the respiratory burst capacity of peritoneal macrophages from mice and rats and peripheral blood mononuclear cells from humans. Because of these observations, the effect of AII on host resistance to bacterial infection was assessed. Intraperitoneal administration of AII was shown to increase host resistance (reduced abscess formation) in an animal model of bacterial peritonitis. Studies were then conducted to assess whether parenteral administration of AII, a clinically relevant route, could affect peritoneal host resistance in a manner similar to that observed after peritoneal administration. These studies showed that subcutaneous administration of AII throughout the postinfection interval increased the level of host resistance to bacterial peritonitis. Furthermore, in a study which compared AII and Neupogen, an agent approved for use for the reduction of febrile neutropenia after myeloablative therapy, daily subcutaneous administration of AII reduced abscess size and incidence, whereas Neupogen did not have any therapeutic benefit in this model. These data suggest that AII may be of therapeutic benefit as an immunomodulatory agent.
Subtilisin Increases Macromolecular Efflux from the Oral Mucosa
Authors: Rubinstein Israel 
Published: July 2002

ABSTRACTThe purpose of this study was to determine whether subtilisin, a potent serine proteinase derived fromBacillusspecies contaminating smokeless tobacco, increases macromolecular efflux from the oral mucosa and, if so, whether local elaboration of bradykinin mediates this response. Using intravital microscopy, I found that suffusion of subtilisin elicits significant, concentration-dependent leaky site formation and an increase in the clearance of fluorescein isothiocyanate-labeled dextran (molecular mass, 70 kDa) from the in situ hamster cheek pouch (P< 0.05). Heat-inactivated subtilisin had no significant effects on macromolecular efflux. Subtilisin-induced responses were significantly attenuated by Hoe 140 and NPC 17647, two structurally distinct selective bradykinin B2receptor antagonists, but not by des-Arg9-[Leu8]bradykinin, a selective bradykinin B1receptor antagonist, or CP-96,345, a selective neurokinin-1 receptor antagonist. Aprotinin, but not leupeptin, significantly attenuated subtilisin-induced increase in macromolecular efflux. Indomethacin had no significant effects on subtilisin-induced responses. Collectively, these data indicate that subtilisin increases the macromolecular efflux from the in situ hamster cheek pouch in a catalytic-site-dependent fashion through local elaboration of bradykinin. This response does not involve the stimulation of local afferent nerves or the production of prostaglandins.
CD8α-Deficient Mice Are Highly Susceptible to 5-Fluorouracil-Induced Lethality
Authors: Itoh Naoto , Nishimura Hitoshi , Matsuguchi Tetsuya , Yajima Toshiki , Mokuno Yasuji , Hiromatsu Takashi , Nimura Yuji , Yoshikai Yasunobu 
Published: July 2002

ABSTRACTIntestinal intraepithelial lymphocytes (i-IEL) expressing CD8α are located in the intestine and may confer protection against invasion of intestinal microflora. We found that mice rendered deficient in CD8α molecules by homologous recombination were susceptible to 5-fluorouracil (5-FU)-induced lethality accompanied by translocation of members of the enterobacteria. The number of i-IEL was greatly reduced on day 6 after 5-FU administration in both CD8α+/−mice and CD8α−/−mice, whereas the recovery of the level of i-IEL thereafter was significantly impaired in CD8α−/−mice compared with that in CD8α+/−mice. The ability of i-IEL to produce gamma interferon in response to immobilized T-cell receptor (TCR) αβ or TCR γδ monoclonal antibodies was significantly lower in CD8α−/−mice than in CD8α+/−mice. Transfer of CD8+i-IEL conferred significant protection against 5-FU-induced lethality in CD8α−/−mice. The results suggest that CD8+i-IEL play an important role in protection against 5-FU-induced lethality with translocation ofEnterobacteriaceae.
Treatment with Megestrol Acetate Improves Human Immunodeficiency Virus-Associated Immune Thrombocytopenia
Authors: Gomez Francisco , Ruiz Pedro , Lopez Rafaela , Rivera Consuelo 
Published: July 2002

ABSTRACTSplenic macrophage Fcγ receptors participate in the pathophysiology of immune cytopenias, and in such disorders, the beneficial effects of glucocorticoids are in part mediated by decreased expression of macrophage Fcγ receptors. In the animal model, progesterones, like glucocorticoids, inhibit expression of these receptors. Megestrol acetate (MA) is a progesterone frequently used for treating human immunodeficiency virus (HIV)-associated anorexia-cachexia. Twenty-eight patients with HIV-associated thrombocytopenia with shortened platelet survival and increased platelet-associated immunoglobulin G (IgG) who were being treated with MA for anorexia-cachexia were prospectively studied for a 6-month period to assess the potential role of progesterones in the treatment of immune thrombocytopenia. Treatment with MA for nonconsecutive periods of 2 months and 1 month significantly increased platelet count and platelet survival without significant alteration of platelet-associated immunoglobulin levels. Of the 28 patients studied, 22 presented a complete response, 19 presented a complete response 1 month after finishing the MA treatment regimen, and 12 remained in complete response for a further month. Expression of Fcγ receptors (FcγRI and FcγRII) by peripheral blood monocytes and the in vitro recognition of IgG-sensitized cells by monocytes were significantly decreased by the MA treatment. Decreased expression and functioning of these receptors significantly correlated with platelet counts and survival times, but no relationship was found with platelet-associated immunoglobulin, circulating immune complexes, body mass index, plasma HIV load, or CD4 lymphocyte levels. These results suggest that treatment with progesterones, like MA, may be an alternative therapy for immune cytopenias, with few side effects.
Leishmania majorReaches Distant Cutaneous Sites Where It Persists Transiently while Persisting Durably in the Primary Dermal Site and Its Draining Lymph Node: a Study with Laboratory Mice
Authors: Nicolas Luc , Sidjanski Sacha , Colle Jean-Hervé , Milon Geneviève 
Published: July 2002

ABSTRACTSo far, studies ofLeishmaniapersistence in mice have used injections of parasites administered either intravenously in the tail vein or subcutaneously in the footpad. These routes poorly reflect the natural conditions when the sandfly delivers metacyclic promastigotes intradermally. In this study B10D2 and BALB/c mice were inoculated within the ear dermis with 104Leishmania majormetacyclic promastigotes. The parasite load was monitored by quantitative PCR in different tissues from the dermal inoculation site to distant tissues. The two sites of multiplication and persistence of parasites were the site ofL. majorinoculation and the draining lymph node (DLN), with a different pattern in the two mouse inbred lines. These two organs were the only sites harboring parasites 12 months postinoculation, with the DLN of BALB/c mice harboring around 107parasites, a stable load from months 3 to 12. In these two sites, 8 and 12 months after inoculation, interleukin 4 (IL-4), gamma interferon, and inducible nitric oxide synthase transcripts parallel the parasite load while IL-10 transcript levels remain high. In addition, at early time points until month 3, parasite DNA was also detected in distant tissues such as the contralateral noninoculated ear or the tail skin, indicating that blood was at least transiently disseminating the parasites. In contrast,L. majorDNA in liver, spleen, and femoral bone marrow remained sporadic in mice of both lines. This study is discussed within the framework ofLeishmaniatransmission from the vertebrate host to the sandfly vector, a complex process still poorly understood.
Pyelonephritogenic Diffusely AdheringEscherichia coliEC7372 Harboring Dr-II Adhesin Carries Classical Uropathogenic Virulence Genes and Promotes Cell Lysis and Apoptosis in Polarized Epithelial Caco-2/TC7 Cells
Authors: Guignot Julie , Breard Jacqueline , Bernet-Camard Marie-Françoise , Peiffer Isabelle , Nowicki Bogdan J. , Servin Alain L. , Blanc-Potard Anne-Beatrice 
Published: July 2002

ABSTRACTDiffusely adhering Escherichia coli (DAEC) strains expressing adhesins of the Afa/Dr family bind to epithelial cells in a diffuse adherence pattern by recognizing a common receptor, the decay-accelerating factor (CD55). Recently, a novel CD55-binding adhesin, named Dr-II, was identified from the pyelonephritogenic strain EC7372. In this report, we show that despite the low level of sequence identity between Dr-II and other members of the Afa/Dr family, EC7372 induces pathophysiological effects similar to those induced by other Afa/Dr DAEC strains on the polarized epithelial cell line Caco-2/TC7. Specifically, the Dr-II adhesin was sufficient to promote CD55 and CD66e clustering around adhering bacteria and apical cytoskeleton rearrangements. Unlike other Afa/Dr DAEC strains, EC7372 expresses a functional hemolysin that promotes a rapid cellular lysis. In addition, cell death by apoptosis or necrosis was observed in EC7372-infected Caco-2/TC7 cells, depending on infection time. Our results indicate that EC7372 harbors a pathogenicity island (PAI) similar to the one described for the pyelonephritogenic strain CFT073, which carries bothhlyandpapoperons. Cumulatively, our findings indicate that strain EC7372 can be considered a prototype of a subclass of Afa/Dr DAEC isolates that have acquired a PAI harboring several classical uropathogenic virulence genes.
Identification of Two Distinct Types of Flagellar Cap Proteins, FliD, in
Pseudomonas aeruginosa
Authors: Arora Shiwani K. , Dasgupta Nandini , Lory Stephen , Ramphal Reuben 
Published: July 2002

ABSTRACT

Binding of
Pseudomonas aeruginosa
strain PAK to mucin has been shown to be mediated by the flagellar cap protein, product of the
fliD
gene. Since the flagellar cap is very likely an exposed structure, the FliD polypeptide should be recognized by the host immune system, analogous to the recognition of dominant epitopes located in the exposed parts of the flagellin polypeptide within the assembled flagellum. In
P. aeruginosa
, a number of distinct flagellin variants are made, and these variable sequences presumably allow the newly infected
P. aeruginosa
to escape recognition by the antibody induced during a previous infection. Since similar mechanisms may direct the selection of FliD variants, we examined the extent of sequence heterogeneity among various FliD sequences among a selected group of
P. aeruginosa
. The results of PCR and nucleotide sequencing of the
fliD
region of eight different
P. aeruginosa
strains (laboratory strains PAK, PAO1, and PA103; clinical strains 1244, CS2, and CS32; cystic fibrosis strains CS29 and MDR) suggested that there were two distinct types of FliD in
P. aeruginosa
, which we named A type and B type. The results of Western blotting using the polyclonal antibodies raised against the purified FliD of A type (PAK) or B type (PAO1) further confirmed the existence of two distinct antigenic types of FliD proteins, with no cross-reactivity between the two serotypes. Further Western immunoblot analysis of the same strains using polyclonal FliC antibody showed that the strains with A-type FliD possessed a-type FliC and those with B-type FliD had b-type FliC. Similar Western blot analyses of 50 more
P. aeruginosa
strains obtained from varied sources revealed that all strains contained either A-type or B-type FliD, suggesting the existence of only two types of FliD in
P. aeruginosa
and indicating that
fliC
and
fliD
were coinherited. This limited diversity of FliC and FliD serotypes seems to be a unique feature of flagellar proteins. A chromosomal mutant having an insertion in the
fliD
gene of
P. aeruginosa
PAO1 was constructed. The motility defect of this mutant and a previously constructed PAK
fliD
mutant was better complemented with the
fliD
gene of the homologous types.
Staphylococcal Enterotoxin A Acts through Nitric Oxide Synthase Mechanisms in Human Peripheral Blood Mononuclear Cells To Stimulate Synthesis of Pyrogenic Cytokines
Authors: Won Shen-Jeu , Huang Wu-Tein , Lai Yih-Shyong , Lin Mao-Tsun 
Published: July 2002

ABSTRACTThe pyrogenic response to supernatant fluids obtained from human peripheral blood mononuclear cells (PBMC) stimulated with staphylococcal enterotoxin A (SEA) was characteristic of a response to an endogenous pyrogen in that it was brief and monophasic and was destroyed by heating supernatant fluids at 70°C for 30 min. The febrile responses were in parallel with the levels of interleukin-1 (IL-1), tumor necrosis factor (TNF), interferon-γ (IFN-γ), IL-2, and IL-6 in supernatant fluids obtained from PBMC treated with SEA. Both the pyrogenicity and the levels of IL-1, TNF, IFN-γ, IL-2, and IL-6 in supernatant fluids started to rise at 6 to 18 h and reached their peak levels at 24 to 96 h after SEA incubation. Both the fever and the increased levels of IL-1, TNF, IFN-γ, IL-2, and IL-6 in supernatant fluids obtained from the SEA-stimulated PBMC were decreased by incubating SEA-PBMC with anisomycin (a protein synthesis inhibitor), aminoguanidine (an inhibitor of inducible nitric oxide synthase [NOS]), or dexamethasone (an inhibitor of NOS). The febrile response to supernatant fluids obtained from the SEA-stimulated PBMC was attenuated by adding either anti-IL-1β, anti-TNF-α, or anti-IFN-γ monoclonal antibody (MAb) to supernatant fluids. The antipyretic effects exerted by anti-IL-1β MAb were greater than those exerted by anti-TNF-α or anti-IFN-γ MAb. The data suggest that SEA acts through the NOS mechanisms in PBMC to stimulate synthesis of pyrogenic cytokines (in particular, the IL-1β).
Interleukin-12 Neutralization Alters Lung Inflammation and Leukocyte Expression of CD80, CD86, and Major Histocompatibility Complex Class II in Mice Infected withHistoplasma capsulatum
Authors: Cain Judith A. , Deepe George S. 
Published: July 2002

ABSTRACTHistoplasma capsulatuminduces a cell-mediated immune response in lungs and lymphoid organs of mammals. Resolution of primary infection in mice depends on interleukin-12 (IL-12), since neutralization of this monokine increases susceptibility to infection. The present study was designed to determine if blockade of IL-12 disrupts the protective immune response by altering the influx of lineage-specific cells into infected lungs and the numbers of cells expressing CD80, CD86, CD119, and major histocompatibility complex class II (MHC II) molecules. In mice given anti-IL-12, there was a 2.5-fold decrease in total numbers of T cells on days 3 to 10 of infection and a 4-fold increase in Mac-1/Gr-1+cells on days 7 and 10 compared to infected controls. CD80+lung cells from anti-IL-12-treated mice were 2- to 3-fold greater than those from controls on days 7 and 10, whereas the total numbers of CD86+cells were 2- to 3-fold less and MHC II+cells were 1.5- to 2-fold less on days 3 and 5. Cells expressing CD119 were reduced 1.5-fold on day 5. Treatment with monoclonal antibodies (MAb) to CD80, CD86, or both reduced the fungal burden slightly compared to that in rat immunoglobulin G-treated controls, whereas after IL-12 neutralization, blocking of CD80 reduced the tissue burden by 2.5-fold and this correlated with a decrease in IL-4. Regardless, mortality was not altered by treatment with MAb to CD80 or CD86. We conclude that (i) IL-12 neutralization alters the nature of the inflammatory response in lungs and the expression of CD80 and CD86 on lineage-specific cells, (ii) the immune response during infection withH. capsulatumis controlled via mechanisms independent of the CD80 and CD86 costimulatory pathways, and (iii) decreased expression of CD86 and MHC II may modulate generation of optimal protective immunity.
Superantigen YPMa Exacerbates the Virulence ofYersinia pseudotuberculosisin Mice
Authors: Carnoy Christophe , Mullet Chantal , Müller-Alouf Heide , Leteurtre Emmanuelle , Simonet Michel 
Published: July 2002

ABSTRACTYersinia pseudotuberculosis, a gram-negative bacterium responsible for enteric and systemic infection in humans, produces a superantigenic toxin designated YPMa (Y. pseudotuberculosis-derived mitogen). To assess the role of YPMa in the pathogenesis ofY. pseudotuberculosis, we constructed a superantigen-deficient mutant and compared its virulence in a mouse model of infection to the virulence of the wild-type strain. Determination of the survival rate after intravenous (i.v.) bacterial inoculation of OF1 mice clearly showed that inactivation ofypmA, encoding YPMa, reduced the virulence ofY. pseudotuberculosis. Mice infected i.v. with 104and 105wild-type bacteria died within 9 days, whereas mice infected with theypmAmutant survived 12 and 3 days longer, respectively. This decreased virulence of theypmAmutant strain was not due to an impaired colonization of the spleen, liver, or lungs. In contrast to i.v. challenge, bacterial inoculation by the intragastric (i.g.) route did not reveal any difference in virulence between wild-typeY. pseudotuberculosisand theypmAmutant since the 50% lethal doses were identical for both strains. Moreover, inactivation ofypmAgene did not affect the bacterial growth ofY. pseudotuberculosisin Peyer's patches, mesenteric lymph nodes (MLNs), and spleen after oral infection. Histological studies of spleen, liver, lungs, heart, Peyer's patches, and MLNs after i.v. or i.g. challenge with the wild type or theypmAmutant did not reveal any feature that can be specifically related to YPMa. Our data show that the superantigenic toxin YPMa contributes to the virulence ofY. pseudotuberculosisin systemic infection in mice.
Mutation ofwaaNReducesSalmonella entericaSerovar Typhimurium-Induced Enteritis and Net Secretion of Type III Secretion System 1-Dependent Proteins
Authors: Watson Patricia R. , Benmore Annette , Khan Shahid A. , Jones Philip W. , Maskell Duncan J. , Wallis Timothy S. 
Published: July 2002

ABSTRACTMutation ofwaaN, a gene involved in lipid A biosynthesis, reduced enteropathogenic responses induced bySalmonella entericaserovar Typhimurium in bovine ligated ileal loops. However, the secretion of key virulence determinants was also reduced, and therefore the reduction in enteropathogenicity cannot be solely attributed to a reduction in biological activity of lipid A.