bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lovastatin Biosynthesis by
Aspergillus terreus
in a Chemically Defined Medium
Authors: Hajjaj Hassan , Niederberger Peter , Duboc Philippe 
Published: July 2002

ABSTRACT

Lovastatin is a secondary metabolite produced by
Aspergillus terreus
. A chemically defined medium was developed in order to investigate the influence of carbon and nitrogen sources on lovastatin biosynthesis. Among several organic and inorganic defined nitrogen sources metabolized by
A. terreus
, glutamate and histidine gave the highest lovastatin biosynthesis level. For cultures on glucose and glutamate, lovastatin synthesis initiated when glucose consumption levelled off. When
A. terreus
was grown on lactose, lovastatin production initiated in the presence of residual lactose. Experimental results showed that carbon source starvation is required in addition to relief of glucose repression, while glutamate did not repress biosynthesis. A threefold-higher specific productivity was found with the defined medium on glucose and glutamate, compared to growth on complex medium with glucose, peptonized milk, and yeast extract.
Expression of the p20 Gene from
Bacillus thuringiensis
H-14 Increases Cry11A Toxin Production and Enhances Mosquito-Larvicidal Activity in Recombinant Gram-Negative Bacteria
Authors: Xu Y. , Nagai M. , Bagdasarian M. , Smith T. W. , Walker E. D. 
Published: July 2002

ABSTRACT

Experimental analyses with recombinant
Escherichia coli
and
Pseudomonas putida
transformed with plasmids bearing genes coding for the Cry11A toxin and P20 protein from
Bacillus thuringiensis
H-14 showed that cells producing both proteins were more toxic when fed to third-instar
Aedes aegypti
larvae than were cells expressing
cry11A
alone; the 50% lethal concentrations were in the range of 10
4
to 10
5
cells/ml. Western blots revealed a higher production of Cry11A when the
p20
gene was coexpressed. Cry11A was detected primarily in insoluble form in recombinant cells. Cry11A was not detected in
P. putida
when P20 was not coproduced, and these recombinants were not toxic to larvae, whereas
P. putida
recombinants producing both proteins were toxic at concentrations similar to those for
E. coli
. A coelution experiment was conducted, in which a
p20
gene construct producing the P20 protein with an extension of six histidines on the C terminus was mixed with the Cry11A protein. The results showed that Cry11A bound to the P20(His
6
) on a nickel chelating column, whereas Cry11A produced without the P20(His
6
) protein was washed through the column, thus indicating that Cry11A and P20 physically interact. Thus, P20 protein either stabilizes Cry11A or helps it attain the folding important for its toxic activity.
Extracellular Polysaccharides of
Rhodococcus rhodochrous
S-2 Stimulate the Degradation of Aromatic Components in Crude Oil by Indigenous Marine Bacteria
Authors: Iwabuchi Noriyuki , Sunairi Michio , Urai Makoto , Itoh Chiaki , Anzai Hiroshi , Nakajima Mutsuyasu , Harayama Shigeaki 
Published: July 2002

ABSTRACT

Rhodococcus rhodochrous
S-2 produces extracellular polysaccharides (S-2 EPS) containing
d
-glucose,
d
-galactose,
d
-mannose,
d
-glucuronic acid, and lipids, which is important to the tolerance of this strain to an aromatic fraction of (AF) Arabian light crude oil (N. Iwabuchi, N. Sunairi, H. Anzai, M. Nakajima, and S. Harayama, Appl. Environ. Microbiol. 66:5073-5077, 2000). In the present study, we examined the effects of S-2 EPS on the growth of indigenous marine bacteria on AF. Indigenous bacteria did not grow significantly in seawater containing AF even when nitrogen, phosphorus, and iron nutrients were supplemented. The addition of S-2 EPS to seawater containing nutrients and AF resulted in the emulsification of AF, promotion of the growth of indigenous bacteria, and enhancement of the degradation of AF by the bacteria. PCR-denaturing gradient gel electrophoresis analyses show that addition of S-2 EPS to the seawater containing nutrients and AF changed the composition of the bacterial populations in the seawater and that bacteria closely related to the genus
Cycloclasticus
became the major population. These results suggest that
Cycloclasticus
was responsible for the degradation of hydrocarbons in AF. The effects of 15 synthetic surfactants on the degradation of AF by indigenous marine bacteria were also examined, but enhancement of the degradation of AF was not significant. S-2 EPS was hence the most effective of the surfactants tested in promoting the biodegradation of AF and may thus be an attractive agent to use in the bioremediation of oil-contaminated marine environments.
Identification, Detection, and Enumeration of Human
Bifidobacterium
Species by PCR Targeting the Transaldolase Gene
Authors: Requena Teresa , Burton Jeremy , Matsuki Takahiro , Munro Karen , Simon Mary Alice , Tanaka Ryuichiro , Watanabe Koichi , Tannock Gerald W. 
Published: July 2002

ABSTRACT

Methods that enabled the identification, detection, and enumeration of
Bifidobacterium
species by PCR targeting the transaldolase gene were tested. Bifidobacterial species isolated from the feces of human adults and babies were identified by PCR amplification of a 301-bp transaldolase gene sequence and comparison of the relative migrations of the DNA fragments in denaturing gradient gel electrophoresis (DGGE). Two subtypes of
Bifidobacterium longum
, five subtypes of
Bifidobacterium adolescentis
, and two subtypes of
Bifidobacterium pseudocatenulatum
could be differentiated using PCR-DGGE.
Bifidobacterium angulatum
and
B. catenulatum
type cultures could not be differentiated from each other. Bifidobacterial species were also detected directly in fecal samples by this combination of PCR and DGGE. The number of species detected was less than that detected by PCR using species-specific primers targeting 16S ribosomal DNA (rDNA). Real-time quantitative PCR targeting a 110-bp transaldolase gene sequence was used to enumerate bifidobacteria in fecal samples. Real-time quantitative PCR measurements of bifidobacteria in fecal samples from adults correlated well with results obtained by culture when either a 16S rDNA sequence or the transaldolase gene sequence was targeted. In the case of samples from infants, 16S rDNA-targeted PCR was superior to PCR targeting the transaldolase gene for the quantification of bifidobacterial populations.
Multisite Comparison of CD4 and CD8 T-Lymphocyte Counting by Single- versus Multiple-Platform Methodologies: Evaluation of Beckman Coulter Flow-Count Fluorospheres and the tetraONE System
Authors: Reimann Keith A. , O'Gorman Maurice R. G. , Spritzler John , Wilkening Cynthia L. , Sabath Daniel E. , Helm Karen , Campbell Donald E. ,   The NIAID DAIDS New Technologies Evaluation Group
Published: July 2002

ABSTRACTNew analytic methods that permit absolute CD4 and CD8 T-cell determinations to be performed entirely on the flow cytometer have the potential for improving assay precision and accuracy. In a multisite trial, we compared two different single-platform assay methods with a predicate two-color assay in which the absolute lymphocyte count was derived by conventional hematology. A two-color method employing lymphocyte light scatter gating and Beckman Coulter Flow-Count fluorospheres for absolute counting produced within-laboratory precision equivalent to that of the two-color predicate method, as measured by coefficient of variation of replicate measurements. The fully automated Beckman Coulter tetraONE System four-color assay employing CD45 lymphocyte gating, automated analysis, and absolute counting by fluorospheres resulted in a small but significant improvement in the within-laboratory precision of CD4 and CD8 cell counts and percentages suggesting that the CD45 lymphocyte gating and automated analysis might have contributed to the improved performance. Both the two-color method employing Flow-Count fluorospheres and the four-color tetraONE System provided significant and substantial improvements in between-laboratory precision of absolute counts. In some laboratories, absolute counts obtained by the single-platform methods showed small but consistent differences relative to the predicate method. Comparison of each laboratory's absolute counts with the five-laboratory median value suggested that these differences resulted from a bias in the absolute lymphocyte count obtained from the hematology instrument in some laboratories. These results demonstrate the potential for single-platform assay methods to improve within-laboratory and between-laboratory precision of CD4 and CD8 T-cell determinations compared with conventional assay methods.
Evaluation of a Capture Screening Enzyme-Linked Immunosorbent Assay for Combined Determination of Immunoglobulin M and G Antibodies Produced during Dengue Infection
Authors: Kit Lam Sai , Lan Ew Cheng , Mitchell Jody L. , Cuzzubbo Andrea J. , Devine Peter L. 
Published: July 2002

ABSTRACT
A commercially available enzyme-linked immunosorbent assay (ELISA) (PanBio Dengue Screening ELISA) that utilized both immunoglobulin M (IgM) and IgG capture in the same microtiter well for the diagnosis of dengue infection was evaluated. Sensitivity in primary and secondary dengue was 95%, while specificity was 94%.
Modified Immunogenicity of a Mucosally Administered Antigen
Authors: Gregory Richard L. 
Published: July 2002

ABSTRACTStreptococcus mutansis present in the saliva of most individuals and is modified by salivary components bound to the cells. These saliva-boundS. mutansare swallowed, exposed to high levels of acidity in the stomach, and presented to the common mucosal immune system. Much effort has been directed to identifying the specificS. mutansantigens that the mucosal immune responses are directed against. However, little is known about the host-altered antigenic determinants that the mucosal immune system recognizes. The immunogenicity of gastrically intubated untreatedS. mutanscells, cells coated with whole human saliva, cells treated with HCl (pH 2.0), and saliva-coated and acid-treated cells in mice was investigated. Saliva and serum samples were assayed by enzyme linked immunosorbent assay for immunoglobulin A (IgA) and IgG antibodies, respectively, against the untreated or treatedS. mutanscells. In general, the levels of salivary IgA and serum IgG antibodies to the antigen against which the mice were immunized were significantly higher (P≤ 0.05). In addition, human saliva and serum samples from 12 subjects were assayed for naturally occurring antibody against the untreated or treatedS. mutanscells. In every case, significantly higher reactivity was directed against the saliva-coated and acid-treated cells followed by the saliva-coatedS. mutans. These results provide evidence for the altered immunogenicity of swallowedS. mutansin humans by coating nativeS. mutansantigens with salivary components and/or denaturing surfaceS. mutansantigens in the acidic environment of the stomach, which would lead to an immune response to modifiedS. mutansdeterminants and not to nativeS. mutansantigens.
In the Absence of Endogenous Gamma Interferon, Mice Acutely Infected withNeospora caninumSuccumb to a Lethal Immune Response Characterized by Inactivation of Peritoneal Macrophages
Authors: Nishikawa Yoshifumi , Tragoolpua Khajornsak , Inoue Noboru , Makala Levi , Nagasawa Hideyuki , Otsuka Haruki , Mikami Takeshi 
Published: July 2002

ABSTRACTFollowing infection withNeospora caninum, BALB/c mice were shown to be resistant to an acute infection but developed a latent chronic infection. However, BALB/c background gamma interferon (IFN-γ)-deficient mice were sensitive to the acute infection. Since the immune response in IFN-γ-deficient mice is scantly known, we examined the function of macrophages, major histocompatibility complex (MHC) class II expression, T-cell responses, and serum cytokine levels in the mice. All IFN-γ-deficient mice died within 9 days of infection withN. caninum, whereas those treated with exogenous IFN-γ lived longer. AlthoughN. caninuminvaded various organs in both types of mice at the early stage of infection, the parasite was not detected in the brains of resistant hosts until 21 days postinfection (dpi). Peritoneal macrophages from IFN-γ-deficient mice were activated by exogenous IFN-γ associated with inhibition of parasite growth and nitric oxide production as were those from BALB/c mice. IFN-γ-deficient mice failed to increase MHC class II expression on macrophages. Moreover, BALB/c mice induced T-cell proliferation while IFN-γ-deficient mice did not. However, in vivo treatment with exogenous IFN-γ induced up-regulated MHC class II expression in IFN-γ-deficient mice. BALB/c mice treated with an antibody to CD4 showed an increase in morbidity and mortality after parasite infection. In serum, significant levels of IFN-γ and interleukin-4 (IL-4) were detected in resistant hosts, whereas IL-10 was detected in IFN-γ-deficient mice. The levels of IL-12 in IFN-γ-deficient mice were higher than those in BALB/c mice at 7 dpi. The present study indicates that early IFN-γ production has a crucial role in the activation of peritoneal macrophages for the induction of protective immune responses againstN. caninum.
Stimulant-Dependent Modulation of Cytokines and Chemokines by Airway Epithelial Cells: Cross Talk between Pulmonary Epithelial and Peripheral Blood Mononuclear Cells
Authors: Krakauer Teresa 
Published: July 2002

ABSTRACTStaphylococcal exotoxins (SE) and lipopolysaccharide (LPS) stimulate cells of the immune system to produce proinflammatory cytokines and chemokines which mediate septic shock and acute lung inflammation. A coculture of human peripheral blood mononuclear cells (PBMC) and pulmonary A549 epithelial cells was used to investigate inflammatory responses triggered by staphylococcal enterotoxin B (SEB), toxic shock syndrome toxin 1, and LPS. The levels of interleukin 1β (IL-1β), IL-6, gamma interferon-inducible protein 10, monocyte chemotactic protein 1 (MCP-1), macrophage inflammatory protein 1α, and RANTES were enhanced by 3.8-, 4.2-, 3.1-, 8.9-, 2-, and 2.9-fold, respectively, in cocultures of SEB-stimulated cells compared to in SEB-stimulated PBMC. In LPS-stimulated cocultures, only MCP-1 and RANTES levels were increased. These data suggest that the modulation of specific cytokines and chemokines is dependent on the stimulus and that there is bidirectional interaction between PBMC and lung epithelial cells to influence the immune response to these different stimuli.
Coinvasion of Dentinal Tubules by
Porphyromonas gingivalis
and
Streptococcus gordonii
Depends upon Binding Specificity of Streptococcal Antigen I/II Adhesin
Authors: Love Robert M. , McMillan Malcolm D. , Park Yoonsuk , Jenkinson Howard F. 
Published: July 2002

ABSTRACT

Cell wall-anchored polypeptides of the antigen I/II family are produced by many species of oral streptococci. These proteins mediate adhesion of streptococci to salivary glycoproteins and to other oral microorganisms and promote binding of cells to collagen type I and invasion of dentinal tubules. Since infections of the root canal system have a mixed anaerobic bacterial etiology, we investigated the hypothesis that coadhesion of anaerobic bacteria with streptococci may facilitate invasive endodontic disease.
Porphyromonas gingivalis
ATCC 33277 cells were able to invade dentinal tubules when cocultured with
Streptococcus gordonii
DL1 (Challis) but not when cocultured with
Streptococcus mutans
NG8. An isogenic noninvasive mutant of
S. gordonii
, with production of SspA and SspB (antigen I/II family) polypeptides abrogated, was deficient in binding to collagen and had a 40% reduced ability to support adhesion of
P. gingivalis
. Heterologous expression of the
S. mutans
SpaP (antigen I/II) protein in this mutant restored collagen binding and tubule invasion but not adhesion to
P. gingivalis
or the ability to promote
P. gingivalis
coinvasion of dentin. An isogenic afimbrial mutant of
P. gingivalis
had 50% reduced binding to
S. gordonii
cells but was unaffected in the ability to coinvade dentinal tubules with
S. gordonii
wild-type cells. Expression of the
S. gordonii
SspA or SspB polypeptide on the surface of
Lactococcus lactis
cells endowed these bacteria with the abilities to bind
P. gingivalis
, penetrate dentinal tubules, and promote
P. gingivalis
coinvasion of dentin. The results demonstrate that collagen-binding and
P. gingivalis
-binding properties of antigen I/II polypeptides are discrete functions. Specificity of antigen I/II polypeptide recognition accounts for the ability of
P. gingivalis
to coinvade dentinal tubules with
S. gordonii
but not with
S. mutans
. This provides evidence that the specificity of interbacterial coadhesion may influence directly the etiology of pulpal and periapical diseases.
Colonic Bacteria Express an Ulcerative Colitis pANCA-Related Protein Epitope
Authors: Cohavy O. , Bruckner D. , Gordon L. K. , Misra R. , Wei B. , Eggena M. E. , Targan S. R. , Braun J. 
Published: July 2002

ABSTRACTBacteria are a suspected pathogenic factor in inflammatory bowel disease, but the identity of the relevant microbial species remains unresolved. The pANCA autoantibody is associated with most cases of ulcerative colitis (UC) and hence reflects an immune response associated with the disease process. This study addresses the hypothesis that pANCA identifies an antigen(s) expressed by bacteria resident in the human colonic mucosa. Libraries of colonic bacteria were generated using aerobic and anaerobic microbiologic culture conditions, and bacterial pools and clonal isolates were evaluated for cross-reactive antigens by immunoblot analysis using the pANCA monoclonal antibody Fab 5-3. Two major species of proteins immunoreactive to pANCA monoclonal antibodies were detected in bacteria from the anaerobic libraries. Colony isolates of the expressing bacteria were identified asBacteroides caccaeandEscherichia coli. Isolation and partial sequencing of theB. caccaeantigen identified a 100-kDa protein without database homologous sequences. TheE. coliprotein was biochemically and genetically identified as the outer membrane porin OmpC. Enzyme-linked immunosorbent assay with human sera demonstrated elevated immunoglobulin G anti-OmpC in UC patients compared to healthy controls. These findings demonstrate that a pANCA monoclonal antibody detects a recurrent protein epitope expressed by colonic bacteria and implicates colonic bacterial proteins as a target of the disease-associated immune response.
Orally AdministeredGiardia duodenalisExtracts Enhance an Antigen-Specific Antibody Response
Authors: Dunn Linda A. , Upcroft Jacqueline A. , Fowler Elizabeth V. , Matthews Ben S. , Upcroft Peter 
Published: July 2002

ABSTRACTWe have identified novel adjuvant activity in specific cytosol fractions from trophozoites ofGiardiaisolate BRIS/95/HEPU/2041 (J. A. Upcroft, P. A. McDonnell, and P. Upcroft, Parasitol. Today, 14:281–284, 1998). Adjuvant activity was demonstrated in the systemic and mucosal compartments whenGiardiaextract was coadministered orally with antigen to mice. Enhanced antigen-specific serum antibody responses were demonstrated by enzyme-linked immunosorbent assay to be comparable to those generated by the “gold standard,” mucosal adjuvant cholera toxin. A source of adjuvant activity was localized to the cytosolic component of the parasite. Fractionation of the cytosol produced fraction pools, some of which, when coadministered with antigen, stimulated an enhanced antigen-specific serum response. The toxic component of conventional mucosal adjuvants is associated with adjuvant activity; therefore, in a similar way, the toxin-like attributes of BRIS/95/HEPU/2041 may be responsible for its adjuvanticity. Complete characterization of the adjuvant is under way.
Administration of Superantigens Protects Mice from LethalListeria monocytogenesInfection by Enhancing Cytotoxic T Cells
Authors: Okamoto Shigefumi , Kawabata Shigetada , Nakagawa Ichiro , Hamada Shigeyuki 
Published: July 2002

ABSTRACTSuperantigens stimulate T-cell-receptor Vβ-selective T-cell proliferation accompanying the release of cytokines, which may eventually protect the host from microbial infections. We investigated here whether superantigens can rescue the host from lethal bacterial infection. Mice were pretreated withStaphylococcus aureusenterotoxin B (SEB) 1 and 2 days before bacterial infection, and the mortality of infected mice was assessed. SEB pretreatment protected mice from lethal infection withListeria monocytogenesbut not from lethal infection withStreptococcus pyogenes. This enhanced protection was also observed upon pretreatment with recombinant streptococcal pyrogenic exotoxin A. Furthermore,L. monocytogenes-specific delayed-type hypersensitivity (DTH) due to type 1 helper T (Th1) cells and the cytotoxicity of CD8+T cells were significantly enhanced after SEB administration and bacterial infection. Depletion of either CD4+T cells or CD8+T cells in SEB-pretreated mice completely abolished this protection. This phenomenon was ascribed to the elimination ofL. monocytogenes-specific CD8+cytotoxic T lymphocytes (CTL). It was found that CD4+T cells contributed to the induction of the CTL populations. Furthermore, SEB pretreatment of heat-killedL. monocytogenes-immunized mice enhanced the protection from challenge ofL. monocytogenes. Taken together, these results indicated that administrations of superantigens protected mice from infection withL. monocytogenes, which was dependent on the enhancedL. monocytogenes-specific CTL activity in the presence of CD4+T cells, and superantigens exhibited adjuvant activity in the immunization against intracellular pathogens.
Immunomodulatory Effects of Anti-CD4 Antibody in Host Resistance against Infections and Tumors in Human CD4 Transgenic Mice
Authors: Herzyk Danuta J. , Gore Elizabeth R. , Polsky Rodd , Nadwodny Kimberly L. , Maier Curtis C. , Liu Susan , Hart Timothy K. , Harmsen Allen G. , Bugelski Peter J. 
Published: July 2002

ABSTRACTAnti-CD4 antibodies, which cause CD4+T-cell depletion, have been shown to increase susceptibility to infections in mice. Thus, development of anti-CD4 antibodies for clinical use raises potential concerns about suppression of host defense mechanisms against pathogens and tumors. The anti-human CD4 antibody keliximab, which binds only human and chimpanzee CD4, has been evaluated in host defense models using murine CD4 knockout-human CD4 transgenic (HuCD4/Tg) mice. In these mice, depletion of CD4+T cells by keliximab was associated with inhibition of anti-Pneumocystis cariniiand anti-Candida albicansantibody responses and rendered HuCD4/Tg mice susceptible toP. carinii, a CD4-dependent pathogen, but did not compromise host defense againstC. albicansinfection. Treatment of HuCD4/Tg mice with corticosteroids impaired host immune responses and decreased survival for both infections. Resistance to experimental B16 melanoma metastases was not affected by treatment with keliximab, in contrast to an increase in tumor colonization caused by anti-T cell Thy1.2 and anti-asialo GM-1 antibodies. These data suggest an immunomodulatory rather than an overt immunosuppressive activity of keliximab. This was further demonstrated by the differential effect of keliximab on type 1 and type 2 cytokine expression in splenocytes stimulated ex vivo. Keliximab caused an initial up-regulation of interleukin-2 (IL-2) and gamma interferon, followed by transient down-regulation of IL-4 and IL-10. Taken together, the effects of keliximab in HuCD4/Tg mice suggest that in addition to depleting circulating CD4+T lymphocytes, keliximab has the capability of modulating the function of the remaining cells without causing general immunosuppression. Therefore, keliximab therapy may be beneficial in controlling certain autoimmune diseases.