Identification and characterisation of multiple linear B cell protectopes in the respiratory syncytial virus G protein

Respiratory syncytial virus (RSV) is an important respiratory pathogen in man, against which no vaccine is available. However, recent evidence suggests that antibodies to the RSV F and G proteins may play an important role in disease prevention. We previously demonstrated that BBG2Na, a subunit vaccine candidate including residues 130-230 of the Long strain G protein, protects rodents against RSV challenge. Using a panel of monoclonal antibodies (MAb) and synthetic peptides, five linear B cell epitopes were identified that mapped to residues 152-163, 165-172, 171-187 (two over-lapping epitopes) and 196-204. Antibody passive transfer and peptide immunisation studies revealed that all were protective. Pepscan analyses of anti-RSV-A and BBG2Na murine polyclonal sera suggested stronger immunogenicity of some protective epitopes (protectopes) in the context of BBG2Na compared with live virus. However, all the identified murine B cell protectopes were conserved in RSV seropositive humans. Should these protectopes correspond with protection in humans, BBG2Na may constitute a very interesting vaccine candidate against RSV.

Differential gene expression in Thermotoga neapolitana in response to growth substrate

We have previously shown that beta-galactosidase activity expressed in Thermotoga neapolitana cells grown on lactose is subject to repression by glucose when they are grown on both substrates whereas beta-galactosidase and beta-glucosidase activities observed in cells grown on cellobiose are not repressed by growth on both glucose and cellobiose. To examine the differential expression of bgalA, bgalB, bglA and bglB in T. neapolitana, total RNA was isolated from cells growing on either glucose, lactose or cellobiose as the sole source of carbon and transcripts encoding these genes were quantitated by Northern blot analyses. BglA expression was induced by cellobiose while bglB was expressed under all three conditions at a lower level. Expression of the beta-galactosidase genes, bgalA and bgalB, was detected only in lactose-grown cells. beta-Glucosidase enzyme activity was only found in cell extracts of cellobiose-grown cells while beta-galactosidase activity was found in both lactose- and cellobiose-grown cell extracts. Our results show that in cellobiose-grown cells, the high beta-glucosidase activity is likely due to expression of bglA and that neither bgalA nor bgalB is responsible for the beta-galactosidase activity.

Staphylococcal surface display and its applications

Novel surface proteins can be introduced onto the bacterial cell surface by recombinant means. Here, we describe the development of such display systems for two food-grade bacteria, Staphylococcus carnosus and Staphylococcus xylosus, and present how such engineered bacteria can be used in different applications. A study will be described in which such staphylococci were employed as vaccine delivery vehicles to elicit protective antibody responses to respiratory syncytial virus (RSV). The use of surface-engineered staphylococci as novel microbial biocatalysts, as a new type of whole-cell diagnostic devices or for adsorption of metal ions with potential environmental or biosensor applications, will also be discussed.

Deuterium-proton exchange on the native wild-type transthyretin tetramer identifies the stable core of the individual subunits and indicates mobility at the subunit interface

Transthyretin is a human protein capable of amyloid formation that is believed to cause several types of amyloid disease, depending on the sequence deposited. Previous studies have demonstrated that wild-type transthyretin (TTR), although quite stable, forms amyloid upon dissociation from its native tetrameric form into monomers with an altered conformation. Many naturally occurring single-site variants of TTR display decreased stability in vitro, manifested by the early onset familial amyloid diseases in vivo. Only subtle structural changes were observed in X-ray crystallographic structures of these disease associated variants. In this study, the stability of the wild-type TTR tetramer was investigated at the residue-resolution level by monitoring (2)H-H exchange via NMR spectroscopy. The measured protection factors for slowly-exchanging amide hydrogen atoms reveal a stable core consisting of strands A, B, E, F, and interestingly, the loop between strands A and B. In addition, the faster exchange of amide groups from residues at the subunit interfaces suggests unexpected mobility in these regions. This information is crucial for future comparisons between disease-associated and wild-type tetramers. Such studies can directly address the regions of TTR that become destabilized as a consequence of single amino acid substitutions, providing clues to aspects of TTR amyloidogenesis.

Regulation of the formation of tumor cell pseudopodia by the Na(+)/H(+) exchanger NHE1

The Na(+)/H(+) exchanger NHE1 is involved in intracellular pH homeostasis and cell volume regulation and accumulates with actin in the lamellipodia of fibroblasts. In order to determine the role of NHE1 following epithelial transformation and the acquisition of motile and invasive properties, we studied NHE1 expression in polarized MDCK cells, Moloney Sarcoma virus (MSV) transformed MDCK cells and an invasive MSV-MDCK cell variant (MSV-MDCK-INV). Expression of NHE1 was significantly increased in MSV-MDCK-INV cells relative to MSV-MDCK and MDCK cells. NHE1 was localized with b-actin to the tips of MSV-MDCK-INV cell pseudopodia by immunofluorescence. Sensitivity of NHE1-mediated (22)Na uptake to ethylisopropylamiloride, a specific inhibitor of NHE1, was increased in MSV-MDCK cells relative to MDCK cells. Changes in intracellular pH induced upon EIPA treatment were also of higher magnitude in MSV-MDCK and MSV-MDCK-INV cells compared to wild-type MDCK cells, especially in Hepes-buffered DMEM medium. Inhibition of NHE1 by 50 microM ethylisopropylamiloride induced the disassembly of actin stress fibers and redistribution of the actin cytoskeleton in all cell types. However, in MSV-MDCK-INV cells, the effect of ethylisopropylamiloride treatment was more pronounced and associated with the increased reversible detachment of the cells from the substrate. Videomicroscopy of MSV-MDCK-INV cells revealed that within 20 minutes of addition, ethylisopropylamiloride induced pseudopodial retraction and inhibited cell motility. The ability of ethylisopropylamiloride to prevent nocodazole-induced formation of actin stress fibers in MSV-MDCK cells was more pronounced in Hepes medium relative to NaHCO(3) medium, showing that NHE1 can regulate actin stress fiber assembly in transformed MSV-MDCK cells via its intracellular pH regulatory effect. These results implicate NHE1 in the regulation of the actin cytoskeleton dynamics necessary for the adhesion and pseudopodial protrusion of motile, invasive tumor cells.

Molecular fingerprinting of Mycobacterium tuberculosis strains isolated in Vietnam using IS6110 as probe

SETTING

Northern and Southern areas of Vietnam.

OBJECTIVE

To study the correlation between DNA fingerprinting of 168 Mycobacterium tuberculosis strains isolated from patients with a particular historical past (political separation of Vietnam for 20 years) and data about geographical origin, drug susceptibility, HIV infection and BCG vaccination status.

METHODS

Comparison of restriction fragment length polymorphism (RFLP) patterns produced by Southern hybridization of Pvull-digested chromosomal DNA.

RESULTS

The number of IS6110 copies for the 168 strains ranges from 0 to 23. Strains originating from the North or the South differ strongly with respect to the number of copies of IS6110. Indeed, the strains originating from the north have predominantly from 3 to 14 IS6110 copies while the southern strains have predominantly from 15 to 23 IS6110 copies. Furthermore, strains isolated in the North are dispersed into 6 groups whereas 80% of the strains isolated in the South form a single group. Moreover, the prevalence of drug resistance is higher in strains isolated in the South than in the North. No noticeable correlation is observed between RFLP patterns, drug susceptibility, or HIV infection.

CONCLUSION

The IS6110 fingerprints of 168 M. tuberculosis strains isolated in Vietnam showed a high range of polymorphism. Only a few strains have been found with no IS6110 (1.8%). The differences between the strains from the North and South, having more than six IS6110, suggests that they derived from ancestral strains that would be distinguishable by the number of IS6110 and their transposition sites throughout the genome. The genomic structure of the population of strains from South Vietnam resembles that of the Beijing strain population. This could account for a similar evolution of M. tuberculosis due to a selection by BCG-induced immunity in the two populations.

Purification and characterization of beta-actin-rich tumor cell pseudopodia: role of glycolysis

The MSV-MDCK-INV invasive variant of Moloney sarcoma virus (mos) transformed MDCK cells express multiple beta-actin-rich pseudopodia (P. U. Le et al., Cancer Res. 58, 1631-1635, 1998). We show here that the tips of these actively protruding cellular domains are morphologically distinct presenting numerous blebs and selectively pass through 1-microm-pore filters. The pseudopodia were purified from the underside of the filters and a major protein component was identified as the glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH). By confocal microscopy, GAPDH colocalized with actin in MSV-MDCK-INV pseudopodia localizing this glycolytic enzyme to this site of active actin polymerization. Inhibition of glycolysis with 2-deoxyglucose or oxamate induced a rapid transformation of beta-actin-rich pseudopodia into extended lamellipodia and prevented cell motility. A localized glycolytic supply of energy therefore regulates the formation of beta-actin-rich pseudopodial protrusions and thereby the motility of invasive tumor cells.

Misoprostol alone--a new method of medical abortion?

Misoprostol shows promise for early termination of pregnancy. The drug is widely available, inexpensive, and easy to administer. Current evidence on the efficacy of potential regimens for early abortion, though, is hard to decipher and often contradictory. Research on a safe, effective, acceptable regimen of misoprostol alone for early abortion is underway. Available data show a wide range in efficacy of various regimens, and additional research is needed to understand this variability. A framework for additional research on misoprostol alone for medical abortion is presented with a focus on the need to evaluate benefits and risks of new regimens in the context of women's options for termination of pregnancy. We discuss the potential usefulness of a regimen with less efficacy than approved medical abortifacients. Research is needed as well on women's ability to self-diagnose incomplete abortion or ongoing pregnancy and the potential for misoprostol to be used as treatment for incomplete abortion in order to evaluate the benefits and risks of misoprostol-alone regimens.

Rapid streptococcal testing in Vietnamese children with pharyngitis

Streptococcal pharyngitis has been a significant public health problem in Vietnam for many years. Accurate diagnosis of the infection, however, has been difficult. We carried out a clinical trial of a rapid streptococcal antigen detection test (Quick-Vue (R) Flex Strep A) on a population of 777 children with pharyngitis seen at the Institute for the Protection of Children's Health (Children's Hospital) in Hanoi, Vietnam. Bacterial culture was performed in parallel with the rapid test on simultaneously obtained throat swab specimens. The rapid test was found to be 89% sensitive and 92% specific (96% in children not on prior antibiotics) compared to culture. The test was also found to be convenient and acceptable to patients and clinicians. A significant benefit of the test is that those children found positive are more likely to be treated with penicillin rather than a broad spectrum antimicrobial, which in turn will reduce the likelihood of resistant infections in the future.

Partial protection to respiratory syncytial virus (RSV) elicited in mice by intranasal immunization using live staphylococci with surface-displayed RSV-peptides

A live bacterial vaccine-delivery system based on the food-grade bacterium Staphylococcus carnosus was used for delivery of peptides from the G glycoprotein of human respiratory syncytial virus, subtype A (RSV-A). Three peptides, corresponding to the G protein amino acids, 144-159 (denoted G5), 190-203 (G9) and 171-188 (G4 S), the latter with four cysteine residues substituted for serines, were expressed by recombinant means as surface-exposed on three different bacteria, and their surface accessibility on the bacteria was verified by fluorescence-activated cell sorting (FACS). Intranasal immunization of mice with the live recombinant staphylococci elicited significant anti-peptide as well as anti-virus serum IgG responses of balanced IgG1/IgG2a isotype profiles, and upon viral challenge with 10(5) tissue culture infectious doses(50) (TCID(50)), lung protection was demonstrated for approximately half of the mice in the G9 and G4 S immunization groups. To our knowledge, this is the first study in which protective immunity to a viral pathogen has been evoked using food-grade bacteria as vaccine-delivery vehicles.

Influence of administration dose and route on the immunogenicity and protective efficacy of BBG2Na, a recombinant respiratory syncytial virus subunit vaccine candidate

The immunogenicity and protective efficacy of BBG2Na, a novel recombinant respiratory syncytial virus subunit vaccine candidate, was assessed in BALB/c mice under various conditions of dose, administration route and number of immunisations. A single intra-peritoneal (i.p.) dose of 2 microg, or two doses of 0.2 microg, were sufficient to induce elevated RSV-A serum antibodies and sterilising lung protective immunity. Serum antibody titres were significantly boosted following second immunisations, but not a third. Of three routes of immunisation, i.p. induced the highest RSV-A antibody titres, followed in efficacy by the intra-muscular (i. m.) and subcutaneous (s.c.) routes. Nonetheless, all three routes induced comparable and sterilising lung protection. In contrast, upper respiratory tract protection was observed only after i.p. vaccination, although significant viral titre reductions were evident following i.m. or s.c. immunisations. Interestingly, Pepscan analyses indicated that antibody epitope usage was highest in i.p. and lowest in i.m. immunised mice, respectively. Nonetheless, all routes resulted in antibody responses to known lung protective epitopes (protectopes). Thus, the prevention of serious lower respiratory tract disease, the principle goal of a RSV vaccine, but not URT infection, is dose dependent but unlikely to be influenced by the route of BBG2Na administration.

Genetic variability determinants of Helicobacter pylori: influence of clinical background and geographic origin of isolates

Helicobacter pylori has an unusual pattern of genetic variation, which complicates research on this organism. To gain a better understanding of the forces behind this phenomenon, the extent to which recombination and single point mutations affect genetic variability in H. pylori was quantified and the influence of both geographical distance and clinical background were assessed. Site-directed restriction-endonuclease digestion of 2 gene fragments was performed on 168 isolates from Montreal and Berlin. Allelic diversity was found to be much higher for H. pylori than for other bacterial species. This finding is consistent with those of previous studies on H. pylori that were conducted using other techniques. However, nucleotide diversity was within the range reported for other bacterial species. Phylogenetic analysis found no grouping of strains with clinical background or geographical origin. Recombination at a rate that resulted in linkage equilibrium within genes can explain these observations.

CD4(+) T-cell-mediated antiviral protection of the upper respiratory tract in BALB/c mice following parenteral immunization with a recombinant respiratory syncytial virus G protein fragment

We analyzed the protective mechanisms induced against respiratory syncytial virus subgroup A (RSV-A) infection in the lower and upper respiratory tracts (LRT and URT) of BALB/c mice after intraperitoneal immunization with a recombinant fusion protein incorporating residues 130 to 230 of RSV-A G protein (BBG2Na). Mother-to-offspring antibody (Ab) transfer and adoptive transfer of BBG2Na-primed B cells into SCID mice demonstrated that Abs are important for LRT protection but have no effect on URT infection. In contrast, RSV-A clearance in the URT was achieved in a dose-dependent fashion after adoptive transfer of BBG2Na-primed T cells, while it was abolished in BBG2Na-immunized mice upon in vivo depletion of CD4(+), but not CD8(+), T cells. Furthermore, the conserved RSV-A G protein cysteines and residues 193 and 194, overlapping the recently identified T helper cell epitope on the G protein (P. W. Tebbey et al., J. Exp. Med. 188:1967-1972, 1998), were found to be essential for URT but not LRT protection. Taken together, these results demonstrate for the first time that CD4(+) T cells induced upon parenteral immunization with an RSV G protein fragment play a critical role in URT protection of normal mice against RSV infection.

Synthesis and characterization of Respiratory Syncytial Virus protein G related peptides containing two disulfide bridges

Respiratory Syncytial Virus (RSV) is the most important cause of bronchiolitis and viral pneumonia in infants and young children. Approximately 100000 children are hospitalized in the USA each year as a result of RSV infections. During the research and development of subunit human Respiratory Syncytial Virus vaccines (hRSV), we have produced numerous synthetic peptides and recombinant proteins containing the four cysteines of the highly conserved central region of the G attachment protein. For several of these disulfide-containing peptides, all possible oxidized isomers were synthesized using various oxidation conditions and resulting in different ratios of isomers. Each isolated isomer was fully characterized by RP-HPLC, FZCE and ES-MS after purification by preparative RP-HPLC. The different cysteine pairings were unambiguously established after enzymatic digestion, LC-MS analysis and peptide microsequencing. These synthesis and analytical methods were developed for the characterization on one hand, of recombinant fusion protein BBG2Na which is currently being investigated in advanced clinical phases as a very promising vaccine candidate, and on the other hand, for peptides which were synthesized to be evaluated as conjugate vaccines or as immunochemical tools, after covalent coupling to carrier proteins. Furthermore, these studies allowed us to determine which of the different possible isomers was the most stable and probably the preferred form in native conditions. Finally, the different oxidation and analysis conditions, should be useful for disulfide pairing studies of other peptides and proteins having the same 'xCxxCxxxxxCxxxCx' framework, such as G proteins of non-human RSV strains, developed by other groups as veterinary vaccine candidates for example.

Host determinants of Helicobacter pylori infection and its clinical outcome

Greater than one-half of the world's population harbors Helicobacter pylori. The majority of infected individuals, however, remain asymptomatic, with only 10% to 20% developing diseases, including peptic ulcer disease, gastric cancer, and gastric mucosa-associated lymphoid tissue lymphoma. This article reviews host factors that may predispose an individual to both the acquisition of H. pylori infection and subsequent clinical outcome. Individuals with specific blood group antigens and human leukocyte antigen genotypes may be more susceptible to H. pylori infection. Additional factors, such as the age of acquisition, the host immune response, the site of infection, acid secretion, and interactions with nonhost factors (including bacterial virulence factors and environmental influences) may play a role in determining clinical outcome. Further investigation is required to clarify the mechanisms by which these interactions occur and, more critically, to determine their relative importance. This knowledge will enable the identification of individuals at risk of developing clinical disease with H. pylori infection.

A surface-displayed cholera toxin B peptide improves antibody responses using food-grade staphylococci for mucosal subunit vaccine delivery

The possibility of improving the antibody responses to a model streptococcal antigen, administered by intranasal immunization as surface-displayed on the food-grade bacterium Staphylococcus carnosus, by co-exposure of a peptide (CTBp) comprising amino acids 50-75 of the cholera toxin B subunit, was investigated. It was found that the introduction of the CTBp into the chimeric surface proteins, containing a serum albumin binding protein (ABP) from streptococcal protein G as model antigen, significantly increased serum IgG responses upon intranasal immunization. Similarly, elicited local IgA responses were also found to be improved. Furthermore, it was demonstrated that live delivery of the staphylococci was required to obtain this effect, since UV-irradiated or heat-killed bacteria exposing the same chimeric surface proteins did not show increased anti-ABP IgG responses.

Identification of multiple protective epitopes (protectopes) in the central conserved domain of a prototype human respiratory syncytial virus G protein

A recombinant fusion protein (BBG2Na) comprising the central conserved domain of the respiratory syncytial virus subgroup A (RSV-A) (Long) G protein (residues 130 to 230) and an albumin binding domain of streptococcal protein G was shown previously to protect mouse upper (URT) and lower (LRT) respiratory tracts against intranasal RSV challenge (U. F. Power, H. Plotnicky-Gilquin, T. Huss, A. Robert, M. Trudel, S. Stahl, M. Uhlén, T. N. Nguyen, and H. Binz, Virology 230:155-166, 1997). Panels of monoclonal antibodies (MAbs) and synthetic peptides were generated to facilitate dissection of the structural elements of this domain implicated in protective efficacy. All MAbs recognized native RSV-A antigens, and five linear B-cell epitopes were identified; these mapped to residues 152 to 163, 165 to 172, 171 to 187 (two overlapping epitopes), and 196 to 204, thereby covering the highly conserved cysteine noose domain. Antibody passive-transfer and peptide immunization studies revealed that all epitopes were implicated in protection of the LRT, but not likely the URT, against RSV-A challenge. Pepscan analyses of anti-RSV-A and anti-BBG2Na murine polyclonal sera revealed lower-level epitope usage within the central conserved region in the former, suggesting diminished immunogenicity of the implicated epitopes in the context of the whole virus. However, Pepscan analyses of RSV-seropositive human sera revealed that all of the murine B-cell protective epitopes (protectopes) that mapped to the central conserved domain were recognized in man. Should these murine protectopes also be implicated in human LRT protection, their clustering around the highly conserved cysteine noose region will have important implications for the development of RSV vaccines.

The prognosis of amaurosis fugax and hemispheric transient ischemic attacks

BACKGROUND

The natural history of amaurosis fugax and of hemispheric transient ischemic attacks (TIAs) may be different. We analysed the ischemic risk factors, carotid status and prognosis with respect to future ischemic events in a cohort of patients who presented with either of these transient ischemic episodes.

METHODS

The charts of patients who presented to our institution between February 1983 and April 1995 with amaurosis fugax or hemispheric TIAs were reviewed. Patients under the age of 45 years with a history of migraine or previous carotid surgery were excluded. Follow-up by a clinical visit or telephone interview was performed. Information was obtained regarding demographic features, presenting symptoms, ischemic risk factors, carotid status (as measured by duplex ultrasonography), type of medical treatment prescribed and occurrence of subsequent ischemic events. Outcome ischemic events were graded as major (myocardial infarction, cerebrovascular accident or death due to either of these) or minor (recurrent amaurosis fugax or hemispheric TIA).

RESULTS

A total of 141 patients were followed for a mean of 47 months. Risk factors were more prevalent in patients with hemispheric TIAs than in those with amaurosis fugax. Most patients had a low degree of carotid stenosis. There was no statistically significant difference in the occurrence of major outcome events between the two groups. Kaplan-Meier survival curves were similar for the two groups.

INTERPRETATION

Amaurosis fugax and hemispheric TIA both carry a risk for future ischemic events. However, we did not find a statistically significant difference in prognosis between the two groups.

The importance of quality control of sputum smear microscopy: the effect of reading errors on treatment decisions and outcomes

SETTING

Ho Chi Minh City, Vietnam.

OBJECTIVE

To evaluate the impact of slide reading errors at peripheral level on case-finding and treatment decisions.

DESIGN

Over a 6-month period in 1997, information on date, type of slide, results of other slides from the patient, and treatment status was collected for all slides from district TB centers detected as having reading errors during smear microscopy quality control re-readings.

RESULTS

Reading errors were detected in 117 slides: 115 (98.3%) were incorrectly read as negative, and 75 (65.2%) of these errors occurred in case-finding slides. In the 75 falsely negative case-finding slides, re-reading resulted in initiation of treatment in 38 patients (50.7%). The remaining 37 (49.3%) had only one positive slide and were told to return for follow-up after 6 months; the two (5.4%) who did return were both diagnosed with active TB. Detection of errors in the 40 false-negative follow-up slides resulted in treatment changes in four patients (10%).

CONCLUSIONS

Quality control plays a critical role in helping to ensure the timely diagnosis and treatment of new TB cases and appropriate management of patients currently on treatment. The usefulness of quality control could be enhanced by focusing greater efforts on case-finding slides initially read as negative.

Protective efficacy against respiratory syncytial virus following murine neonatal immunization with BBG2Na vaccine: influence of adjuvants and maternal antibodies

Alum-adsorbed BBG2Na, a recombinant vaccine derived in part from the respiratory syncytial virus (RSV) subgroup A G protein, induced moderate antibody titers after 1 immunization in 1-week-old mice but conferred complete lung protection upon RSV challenge. The anti-BBG2Na IgG1-IgG2a neonatal isotype profile was suggestive of dominant Th2 responses compared with those in adults. Formulation of BBG2Na with a Th1-driving adjuvant efficiently shifted neonatal responses toward a more balanced and adultlike IgG1-IgG2a profile without compromising its protective efficacy. BBG2Na-induced protective immunity was maintained even after early life immunization in the presence of high titers of maternal antibodies. Under these conditions, the protective efficacy (86%-100%) reflected the high capacity of the nonglycosylated G2Na immunogen to escape inhibition by RSV-A-induced maternal antibodies. Thus, immunization with BBG2Na protected against viral challenge despite neonatal immunologic immaturity and the presence of maternal antibodies, two major obstacles to neonatal RSV vaccine development.

Identification of three alternatively spliced variants of human CD28 mRNA

CD28, expressed by T cells, plays a central role in providing costimulatory signals to T cells. The cd28 gene is organized into 4 exons. An alternatively spliced CD28 mRNA lacking most of the exon 2 has been previously evidenced. We report here that non stimulated human T cells express three additional alternatively spliced variants of CD28 mRNA (CD28a-c) in. The CD28a variant, expressed at similar levels to that of the full length CD28 mRNA encoding for the membrane form, lacks exon 3. This deletion introduces (i) a frame shift resulting in the addition of two extra amino acids and a premature stop codon and, (ii) induces the loss of the transmembrane region, suggesting that it could encodes for a soluble monomeric molecule which conserves the binding sites of CD28. The CD28b and CD28c variants, expressed at a low level compared with CD28a, are generated by deletion of most of the 3' end of exon 2 plus exon 3 and exon 2 plus exon 3, respectively. Activated T cells express only the membrane CD28 mRNA. These results suggest that resting human T cells may constitutively express both membrane and soluble CD28 which can differentially regulate the outcome of the T cell response.

Absence of lung immunopathology following respiratory syncytial virus (RSV) challenge in mice immunized with a recombinant RSV G protein fragment

The relative immunopathogenic potential of a recombinant fusion protein incorporating residues 130-230 of respiratory syncytial virus (RSV-A) G protein (BBG2Na), formalin-inactivated RSV-A (FI-RSV), and phosphate-buffered saline (PBS) was investigated in mice after immunization and RSV challenge. FI-RSV priming resulted in massive infiltration of B cells and activated CD4(+) and CD8(+) T lymphocytes in mediastinal lymph nodes (MLN) and lungs, where eosinophilia and elevated IFN-gamma, IL-2, -4, -5, -10, and -13 mRNA transcripts were also detected. PBS-primed mice showed only elevated pulmonary IL-2 and IFN-gamma mRNAs, while an activated CD8(+) T cell peak was detected in MLN and lungs. Cell infiltration also occurred in MLN of BBG2Na-immunized mice. However, there was no evidence of T cell, B cell, or granulocyte infiltration or activation in lungs, while transient transcription of Th1-type cytokine genes was evident. The absence of pulmonary infiltration is unlikely due to insufficient viral antigen. Thus, this recombinant fusion RSV G fragment does not prime for adverse pulmonary immunopathologic responses.

Mitochondrial DNA phylogeny of West African aplocheiloid killifishes (Cyprinodontiformes, Aplocheilidae)

African killifishes (Cyprinodontiformes, Aplocheilidae) historically associated with the genus Aphyosemion occur in two geographically distinct regions. One assemblage from far West Africa has been previously shown to be monophyletic and not closely related to the remaining eastern species of Aphyosemion (W. J. Murphy and G. E. Collier, 1997, Mol. Biol. Evol. 14, 790-799). This is supported by further analysis of mitochondrial DNA sequences from 19 species from 21 different localities, representing 19 of the putative 22 species of this western group. Phylogenetic analyses of these data corroborate the monophyly and sister-group relationship of two distinct groups of taxa: Callopanchax and Scriptaphyosemion. Many of the relationships within Scriptaphyosemion suggest that these taxa may have radiated within a short period of time relative to the rate of substitutions within these sequences. A third, and possibly paraphyletic group of species, Archiaphyosemion, is suggested to be the sister taxon to the first two groups. These three groups are elevated to generic rank and together represent the sister group to the genus Epiplatys. Biogeographic inference suggests that the ancestors of this group diversified westward through upland habitat and have only relatively recently entered the lowland habitats in which Scriptaphyosemion and Callopanchax have diversified, with the latter genus reacquiring a suite of traits collectively referred to as annualism.

Surface display of functional fibronectin-binding domains on Staphylococcus carnosus

The surface expression in Staphylococcus carnosus of three different fibronectin binding domains (FNBDs), derived from fibronectin binding proteins of Streptococcus dysgalactiae and Staphylococcus aureus, has been investigated. Surface localization of the chimeric proteins containing the FNBDs was demonstrated. All three surface-displayed FNBDs were demonstrated to bind fibronectin in whole-cell enzyme-linked binding assays. Furthermore, for one of the constructs, intranasal immunizations with the recombinant bacteria resulted in improved antibody responses to a model immunogen present within the chimeric surface proteins. The implications of the results for the design of live bacterial vaccine delivery systems are discussed.

An in vitro selected binding protein (affibody) shows conformation-dependent recognition of the respiratory syncytial virus (RSV) G protein

Using phage-display technology, a novel binding protein (Z-affibody) showing selective binding to the RSV (Long strain) G protein was selected from a combinatorial library of a small alpha-helical protein domain (Z), derived from staphylococcal protein A (SPA). Biopanning of the Z-library against a recombinant fusion protein comprising amino acids 130-230 of the G protein from RSV-subgroup A, resulted in the selection of a Z-affibody (Z(RSV1)) which showed G protein specific binding. Using biosensor technology, the affinity (K(D)) between Z(RSV1) and the recombinant protein was determined to be in the micromolar range (10(-6) M). Interestingly, the Z(RSV1) affibody was demonstrated to also recognize the partially (54%) homologous G protein of RSV subgroup B with similar affinity. Using different recombinant RSV G protein derived fragments, the binding was found to be dependent on the presence of the cysteinyl residues proposed to be involved in the formation of an intramolecular disulfide-constrained loop structure, indicating a conformation-dependent binding. Results from epitope mapping studies, employing a panel of monoclonal antibodies directed to different RSV G protein subfragments, suggest that the Z(RSV1) affibody binding site is located within the region of amino acids 164-186 of the G protein. This region contains a 13 amino acid residue sequence which is totally conserved between subgroups A and B of RSV and extends into the cystein loop region (amino acids 173-186). The potential use of the RSV G protein-specific Z(RSV1) affibody in diagnostic and therapeutic applications is discussed.

The serum albumin-binding region of streptococcal protein G (BB) potentiates the immunogenicity of the G130-230 RSV-A protein

BBG2Na is a protein comprising residues 130-230 of the respiratory syncytial virus subgroup A (RSV-A) G protein (G2Na) fused to the albumin-binding domain of streptococcal G protein (BB). BBG2Na was cloned, expressed in Escherichia coli and renaturated. In rodent models, this subunit RSV vaccine adjuvanted in Alhydrogel induced specific antibodies and conferred protection to RSV infection. Comparison of the antibody production in a BALB/c mouse model revealed that BBG2Na induced a stronger and earlier G2Na antibody response than G2Na alone, without altering the IgG subclass distribution. To address the role of the BB part, we explored its carrier properties and showed that it is a Th dependent antigen, generating a more potent G2Na-specific B cell memory response and able to generate Th cells that provide help for G2Na antibody production.

Quality control of smear microscopy for acid-fast bacilli: the case for blinded re-reading

SETTING

Quality control of sputum smear microscopy, which is essential for ensuring correct tuberculosis (TB) diagnosis, is often performed through the unblinded rereading of all positive slides and a sample of negative slides.

OBJECTIVE

To assess misclassification error introduced by knowledge of prior results.

METHODS

The Southern Vietnam Regional TB Laboratory prepared three gold-standard sets of 750 slides: an unblinded set, an unblinded set in which 13% of negative slides were replaced by weakly positive slides purposefully mislabelled as negative, and a blinded set. Six provincial technicians who normally perform district quality control each reread 125 slides from each set.

RESULTS

In the three sets only one negative slide was misread as positive. In the unblinded set (referent), 2.9% (9/311) positive slides were misread as negative, compared with 18.7% (57/305) in the blinded set (prevalence ratio [PR] = 6.5; 95% confidence interval [CI] 3.3-12.8; P < 0.001), and 11.3% (33/293) in the unblinded set with mislabelled slides (PR = 3.9; 95%CI 1.9-8.0; P < 0.001).

CONCLUSIONS

False-negative error was more common than false-positive error. Knowledge of prior reading influences re-reading. Blinded re-reading of systematically selected slides would appear preferable, although this method requires high levels of proficiency among quality control technicians.

Disruption of the utrophin-actin interaction by monoclonal antibodies and prediction of an actin-binding surface of utrophin

Monoclonal antibody (mAb) binding sites in the N-terminal actin-binding domain of utrophin have been identified using phage-displayed peptide libraries, and the mAbs have been used to probe functional regions of utrophin involved in actin binding. mAbs were characterized for their ability to interact with the utrophin actin-binding domain and to affect actin binding to utrophin in sedimentation assays. One of these antibodies was able to inhibit utrophin-F-actin binding and was shown to recognize a predicted helical region at residues 13-22 of utrophin, close to a previously predicted actin-binding site. Two other mAbs which did not affect actin binding recognized predicted loops in the second calponin homology domain of the utrophin actin-binding domain. Using the known three-dimensional structure of the homologous actin-binding domain of fimbrin, these results have enabled us to determine the likely orientation of the utrophin actin-binding domain with respect to the actin filament.

Establishment of drug chests in commune health stations in Vietnam, Bamako Initiative

In remote areas in Vietnam essential drugs are often not available. Some of the reasons are inadequate resources and failure of distribution. All activities at the health stations are very weak, partly because of inappropriate usage of drugs and lack of fund for buying drugs. The object of the project was to establish sustainable provision of essential drugs for commune health stations in rural areas, to teach the health personnel the importance of essential drugs and to create incentives for the staff and a certain surplus for other health activities. Four District Health Centers (DHC) and 10 Health Stations (HS), 2-4 in each DHC were selected. A pharmacist was made monitor of the project. The health personnel were trained in proper use of drugs, drug prescription, price setting, book keeping and management of pharmacy. Written guidelines were produced. One person was responsible for the drug chest at each HS. After recognizing the aim of the project and signing the contract by which the responsible person was bound, the initial capital was given free. The DHC was responsible for the supervision and advice to the HS. Reporting on prescribed drugs, buying and selling price, profit and fund left took place monthly. Monitoring of recovery of capital, turnover rate, rate of essential drugs and incentives for staff were monitored on forms and quarterly collected by the monitor on his visits. The HS were visited half-yearly by a steering group. All ten HS had been able to establish and maintain the pharmacy and to fully recover or even increase the capital and to create a surplus. Seven out of ten HSs had a turnover rate of more than one. The rate of essential drugs sold was more than 60% in seven pharmacies. The interest rate of 18% on average was used for incentives for staff, to provide drugs for those who cannot pay and for equipment for the HS. The cooperation between the DHC and the HS became closer. Establishment of drug chests seems to be a reasonable strategy of reinforcing primary health. Much attention should be paid on training of staff, monitoring, supervision and integration of health services.

Influence of parasympathetic dysfunction and hyperinsulinemia on the hemodynamic response to an isometric exercise in non-insulin-dependent diabetic patients

The handgrip test has long been used as a test for investigating cardiac autonomic neuropathy in diabetic patients. However, the factors involved in the hemodynamic response to the handgrip test have not been thoroughly studied. The aim of this study was to investigate blood pressure (BP) and heart rate (HR) responses to an isometric test in non-insulin-dependent diabetics (NIDDs) and to correlate the results with vagal function evaluated by three standardized tests and with plasma insulin levels. Fifty-five NIDDs, 35 of whom had one to three abnormal parasympathetic tests (PS+), were compared with 10 healthy control subjects. Fasting and postprandial plasma insulin levels were significantly higher in the PS+ than in the PS- patients. Resting HR correlated significantly with log fasting and postprandial insulin. In PS+ NIDDs, resting HR was significantly higher than in PS- patients. Age-matched comparisons also showed that resting systolic BP was significantly higher in PS+ patients than in controls. In PS- patients, the mean acceleration of HR was significantly higher than in the control group from the second to the fifth minute, and the BP response was also higher than in controls. These data suggest that (1) sympathetic response to an isometric exercise is increased in PS- NIDDs; (2) cardiac parasympathetic dysfunction is associated with a more severe insulin resistance; and (3) the subsequent higher plasma insulin level may contribute to the increase in resting HR and BP through sympathetic activation while limiting the hemodynamic response to an isometric exercise through its vasodilative effect.

Clinical significance of histiocytes in the detection of endometrial adenocarcinoma and hyperplasia

The purpose of this case-control study was to determine the clinical significance of histiocytes and normal endometrial cells as cytologic markers of adenocarcinoma or hyperplasia of the endometrium. Cervical-vaginal smears obtained in 102 patients with mean age 59.7 yr with abnormal uterine bleeding and endometrial pathology, and 101 controls with mean age 56.5 yr with postmenopausal bleeding and whose cytologic smear was negative, were evaluated. Histiocytes alone failed to predict either endometrial adenocarcinoma (odds ratio [OR], 1.02; 95% confidence interval [CI], 0.32-3.22) or hyperplasia (OR, 1.10; 95% CI, 0.37-3.30). The odds of endometrial carcinoma in symptomatic, postmenopausal women was three times greater in the presence of histiocytes with phagocytosis of acute inflammatory cells (PIC) (OR, 3.00; 95% CI, 1.16-7.70). Endometrial hyperplasia was more frequently observed when cervical smears contained normal endometrial cells (OR, 4.09; 95% CI, 1.14-14.67). Only histiocytes with PIC and normal endometrial cells carry a three- and fourfold greater likelihood of coexistent endometrial adenocarcinoma and hyperplasia, respectively. Such strong association may require endometrial biopsy or transvaginal ultrasonography to uncover lesional tissue in the endometrial cavity.

Artemisinin induces omeprazole metabolism in human beings

OBJECTIVE

This study investigated whether time-dependent artemisinin pharmacokinetics correlated to CYP3A4 or CYP2C19 activity in vivo.

METHODS

Artemisinin (two oral doses per day of 250 mg) was given to nine healthy Vietnamese subjects for 7 days (day 1 to day 7). Single 20 mg doses of omeprazole were given orally on day -7, day 1, and day 7. Single doses of artemisinin and omeprazole were given in combination on day 14 after a 6-day washout period. The pharmacokinetics of artemisinin, omeprazole, hydroxyomeprazole, and omeprazole sulfone were evaluated on days -7, 1, 7, and 14. On the same days urine was collected for the determination of 6beta-hydroxycortisol and cortisol excretion.

RESULTS

Areas under plasma concentration-time curves (AUC) for artemisinin and omeprazole decreased on day 7 to 20% (95% confidence intervals, 13%, 28%) and 35% (25%, 46%), respectively, compared with values on day 1. AUC ratios for hydroxyomeprazole/omeprazole increased 2.2-fold (1.7, 2.7) on day 7 compared with values on day 1. All values were normalized at day 14. There were no significant changes in the omeprazole sulfone/omeprazole ratio or in the 6beta-hydroxycortisol/cortisol ratio between the study days. In one subject found to have poor CYP2C19 metabolization, the elimination of omeprazole increased after artemisinin exposure, with no change in the hydroxyomeprazole/omeprazole AUC ratio.

CONCLUSION

Artemisinin did not alter CYP3A4 activity, whereas an increase in CYP2C19 activity was observed. The increased elimination of omeprazole in both poor and extensive CYP2C19 metabolizers suggests artemisinin induces both CYP2C19 and another enzyme.

The recombinant Klebsiella pneumoniae outer membrane protein OmpA has carrier properties for conjugated antigenic peptides

Klebsiella pneumoniae OmpA, the 40-kDa major protein of the outer membrane, was cloned and expressed in Escherichia coli. The recombinant protein was produced intracellularly in E. coli as inclusion bodies. Fusion of a short peptide to the N-terminus of native P40 facilitated high-level expression of the recombinant protein. Purified recombinant P40 was analyzed to verify purity and structural integrity. The molecular mass of purified recombinant P40 determined by electrospray mass spectrometry was 37,061 Da, in agreement with the theoretical mass deduced from the DNA sequence. Specific proliferation of recombinant-P40-primed murine lymph node cells in response to recombinant P40 stimulation in vitro indicated the presence of a T-cell epitope on recombinant P40. The induction of high serum antibody titers to a synthetic peptide derived from the attachment protein G of the respiratory syncytial virus when chemically coupled to recombinant P40 indicated that the protein had potent carrier properties.

Acute and chronic phases of Toxoplasma gondii infection in mice modulate the host immune responses

Murine antibody responses to soluble proteins are generally restricted to the immunoglobulin G1 (IgG1) isotype. When mice were infected with Toxoplasma gondii Beverley and concomitantly immunized with a soluble unrelated protein antigen, a modification in the isotypic distribution of antibodies directed against this nonparasite antigen was observed, with a preferential production of IgG2a. Interestingly, when mice were immunized with a soluble protein antigen during the chronic phase (day 40) of infection with T. gondii Beverley, a similar modification in the isotypic distribution of antiprotein antibodies was observed.

Artemisinin pharmacokinetics in healthy adults after 250, 500 and 1000 mg single oral doses

Eight healthy male, Vietnamese subjects were administered 1 x 250, 2 x 250, and 4 x 250 mg artemisinin capsules in a cross-over design with randomized sequence with a 7-day washout period between administrations. The inter-individual variability in artemisinin pharmacokinetics was large with parameter coefficient of variation (CV) typically between 50-70%. The parameter with the smallest variability was the elimination half-life (CV approximately equal to 30-40%). Analysis of variance indicated also a large intra-subject variability. (CV, or = 24%) for the dose-normalized area under the plasma concentration-time curve (AUC/dose). The pharmacokinetic results suggested artemisinin to be subject to high pre-systemic extraction. Artemisinin half-life could not predict the extent of in vivo exposure to the drug, there being no correlation between half-life and oral clearance. Artemisinin oral plasma clearance was about 400 L h-1 exhibiting a slight decrease with dose, although the effect was weak. Thus results from studies using different artemisinin doses may, within the studied dose range, be compared without the complication of disproportionate changes in drug exposure with varying dose levels. Half-lives appeared to increase with dose. An observed period effect in the analysis of variance was tentatively associated with time-dependency in artemisinin pharmacokinetics. There was a high correlation between artemisinin plasma concentrations determined at various time-points after drug administration and the AUCs after the 500 and 1000 mg doses, but less so after the 250 mg dose. This may show a tentative approach to assess the systemic exposure of the patients to artemisinin from the determination of artemisinin plasma concentrations in one or two plasma samples only. Artemisinin was well tolerated with no apparent dose or time dependent effects on blood pressure, heart rate or body temperature.

Increased beta-actin expression in an invasive moloney sarcoma virus-transformed MDCK cell variant concentrates to the tips of multiple pseudopodia

An invasive variant of Moloney sarcoma virus-transformed MDCK cells (MSV-MDCK-INV), which was isolated by the repeated selection of cells that successfully traversed a Matrigel-coated filter, exhibits increased motile ability and presents an elongated cell shape and numerous pseudopodia. Although stress fibers are present in both MDCK and MSV-MDCK cells, MSV-MDCK-INV cells contain no stress fibers and exhibit a dense concentration of actin at the tips of pseudopodia. Relative to both MDCK and MSV-MDCK cells, the MSV-MDCK-INV cells exhibit increased expression of beta-actin and redistribution of beta-actin to the tips of pseudopodia. These actin concentrations are enriched in both F- and G-actin and, thus, represent dynamic regions of actin cytoskeleton remodeling. The acquisition of invasive properties by epithelial transformants is, therefore, associated with the increased expression of beta-actin and its concentration in actin-rich domains, which may drive pseudopodial extension and facilitate tumor cell invasion.

Artemisinin kinetics and dynamics during oral and rectal treatment of uncomplicated malaria

OBJECTIVE

To compare parasite clearance times after oral and rectal administration of artemisinin in adults with uncomplicated malaria and to relate pharmacodynamics with artemisinin kinetics and to disclose any pharmacokinetic changes during treatment.

METHODS

Thirty male Vietnamese patients with falciparum malaria were randomized to treatment with 500 mg artemisinin daily by either the oral or rectal route of administration. Parasite densities in capillary blood were determined by microscopy every 4 to 6 hours. Artemisinin plasma concentrations on the first and last day of treatment were determined by HPLC and unbound fractions in plasma were determined by ultrafiltration.

RESULTS

Mean parasite clearance times and 95% confidence intervals (95% CI) were 25 (95% CI, 16 to 33) and 29 (95% CI, 23 to 35) hours during oral and rectal treatment, respectively. The bioavailability after rectal relative to oral artemisinin was 30%. Artemisinin areas under the plasma concentration-time curve (AUC) on the fifth (last) day of oral or rectal treatment were 30% (95% CI, 4% to 56%) and 40% (95% CI, -6% to 91%), respectively, of those after the first dose. The fraction unbound in plasma was 15% (95% CI, 12% to 19%), increasing marginally during treatment. No relationship was found between main clinical end points and drug exposure, although indices for the rapidity of response onset were lower after oral treatment and correlated to unbound AUC values (rS = -0.7; p < 0.001).

CONCLUSIONS

The similarity in parasite clearance times despite lower drug levels during rectal treatment suggests that initial oral doses may be unnecessarily high. The singular time dependency of artemisinin pharmacokinetics, attributed to autoinduction of drug elimination, has possible implications for combination chemotherapy. Decreasing artemisinin concentrations during treatment may partly explain recrudescences and increase the risk for resistance development.

Chromosomal sequencing using a PCR-based biotin-capture method allowed isolation of the complete gene for the outer membrane protein A of Klebsiella pneumoniae

By employing a novel biotin- and PCR-assisted capture method, which allows determination of unknown sequences on chromosomal DNA, the gene for the outer membrane protein A (OmpA) of Klebsiella pneumoniae has been isolated and sequenced to completion. The method involves linear amplification of DNA from a biotinylated primer annealing to a region with known sequence. After capture of the amplified single-stranded DNA on to paramagnetic beads, unspecifically annealing primers, i.e. arbitrary primers, were used to generate sequences with only partly determined nt sequences. The homology of the sequenced gene to ompA of related bacteria is discussed, and the gene fragment was assembled for intracellular expression in Escherichia coli, and two different fusion proteins were produced and recovered with good yields. The importance of the novel chromosomal sequencing method for gene isolation in general and the potential use of the OmpA fusion proteins are discussed.

Vascular endothelial growth factor is essential for corpus luteum angiogenesis

The development and endocrine function of the ovarian corpus luteum (CL) are dependent on the growth of new capillary vessels. Although several molecules have been implicated as mediators of CL angiogenesis, at present there is no direct evidence for the involvement of any. Here we report the unexpected finding that treatment with truncated soluble Flt-1 receptors, which inhibit vascular endothelial growth factor (VEGF) bioactivity, resulted in virtually complete suppression of CL angiogenesis in a rat model of hormonally induced ovulation. This effect was associated with inhibition of CL development and progesterone release. Failure of maturation of the endometrium was also observed. Areas of ischemic necrosis were demonstrated in the corpora lutea (CLs) of treated animals. However, no effect on the preexisting ovarian vasculature was observed. These findings demonstrate that, in spite of the redundancy of potential mediators, VEGF is essential for CL angiogenesis. Furthermore, they have implications for the control of fertility and the treatment of ovarian disorders characterized by hypervascularity and hyperplasia.

Oleanane saponins from Polyscias fruticosa

From the leaves and roots of Polyscias fruticosa, eight new oleanolic acid saponins named polysciosides A to H were isolated together with three known saponins. The structures of the saponins were established by means of spectral data, particularly NMR, which included COSY, HSQC, HMBC, HOHAHA and ROESY techniques.

Flow cytometric quantification of surface-displayed recombinant receptors on staphylococci

Surface display of recombinant proteins on bacteria and phages has become an important tool in bioscience. To evaluate the various host systems, a great need exists for quantitative methods to determine the densities of displayed proteins and peptides on the bacteria and phage surfaces. Here we describe how a method previously applied for quantification of surface proteins on mammalian cells has been adapted for quantification of chimeric receptors surface-displayed on bacteria; in this study, the bacteria being recombinant staphylococci. The presented method takes advantage of fluorescence-activated cell sorting (FACS) technology and a new type of nonfluorescent plastic beads, similar in size (2 microns in diameter) to bacterial cells, and thus suitable for generation of calibration curves from which the number of chimeric receptors can be obtained. The method was used to estimate the number of antigenic sites on two types of recombinant staphylococci, both carrying heterologous chimeric receptors, and it was found that the recombinant Staphylococcus carnosus cells carried approximately 10(4) surface-displayed antigenic sites, while recombinant Staphylococcus xylosus exposed approximately 3 x 10(3) sites per cell. The use of the deviced method for different applications is discussed.

Challenge of BALB/c mice with respiratory syncytial virus does not enhance the Th2 pathway induced after immunization with a recombinant G fusion protein, BBG2NA, in aluminum hydroxide

The polypeptide of aa 130-230 of the G protein (G2Na) of respiratory syncytial virus (RSV) was fused to BB, the albumin-binding region of streptococcal G protein, producing BBG2Na, which induced protective immune responses in rodent models. Evaluation of the immune response in mice immunized with BBG2Na in the adjuvant alhydrogel revealed high amounts of interleukin (IL)-5 and some IL-4 in splenocytes restimulated in vitro. This is compatible with a Th2 response. The activation of the Th2 pathway in such mice was further supported by the detection of IL-5 and G2Na-specific IgE in vivo. Of interest, in contrast to immunization with formalin-inactivated RSV, immunization of mice with BBG2Na followed by intranasal RSV challenge did not lead to increased production of IL-5- or G2Na-specific IgE. However, IgG1- and IgG2a-specific antibodies were boosted. These results demonstrate that the Th2 pathway is not enhanced by RSV challenge in BBG2Na-immunized mice.

Surface display of the cholera toxin B subunit on Staphylococcus xylosus and Staphylococcus carnosus

The heterologous surface expression of the cholera toxin B subunit (CTB) from Vibro cholerae in two staphylococcal species, Staphylococcus xylosus and Staphylococcus carnosus, has been investigated. The gene encoding native CTB (103 amino acids) was introduced into gene constructs encoding chimeric receptors designed to be translocated and anchored on the outer cell surface of the staphylococci. Since functionality of CTB is correlated with its ability to form pentamers and the capacity of the pentameric CTB to bind the GM1 ganglioside, both the surface accessibility and the functionality of the surface-displayed CTB receptors were evaluated. It could be concluded that the chimeric receptors were targeted to the cell wall of the staphylococci, since they could be released by lysostaphin treatment and, after subsequent affinity purification, identified as full-length products by immunoblotting. Surface accessibility of the chimeric receptors was demonstrated by a colorimetric assay and by immunofluorescence staining with a CTB-reactive rabbit antiserum. Pentamerization was investigated by using a monoclonal antibody described to be specific for pentameric CTB, and the functionality of the receptors was tested in a binding assay with digoxigenin-labelled GM1. It was concluded that functional CTB was present on both types of staphylococci, and for S. carnosus, the reactivity to the pentamer-specific monoclonal antibody and in the GM1 binding assay was indeed significant. The implications of the results for the design of live bacterial vaccine delivery systems intended for administration by the mucosal route are discussed.

Induction of protective immunity in rodents by vaccination with a prokaryotically expressed recombinant fusion protein containing a respiratory syncytial virus G protein fragment

A subunit approach to the development of a respiratory syncytial virus (RSV) vaccine was investigated. It involved the production, in Escherichia coli, of an RSV (Long) G protein fragment (G2Na) as a C-terminal fusion partner to an albumin binding region (BB) of streptococcal protein G. G2Na incorporated amino acid residues 130-230 and was specifically recognized by murine anti-RSV-A polyclonal serum. In mice, intraperitoneal immunization with BBG2Na induced high anti-RSV-A serum ELISA titers and low to moderate neutralization activity. The immune response induced by BBG2Na demonstrated a potent protective efficacy against upper and lower respiratory tract RSV-A infection. The immunogenicity and protective efficacy of BBG2Na was maintained for at least 47 and 48 weeks, respectively, and was as potent and durable as live RSV-A administered in a similar fashion. Intramuscular immunization of cotton rats with BBG2Na protected lungs from both homologous and heterologous virus challenge. In contrast to mice, however, cotton rat nasal tracts were not protected after BBG2Na immunization. Consistent with antibody-mediated protection, virus was cleared within 24 hr from the lungs of BBG2Na-immunized mice. The anti-RSV-A antibodies induced in mice were exclusively of the IgG1 isotype and were detected in the serum, lungs, and nasal tracts. Passive transfer of these antibodies prevented acute, and eliminated chronic, RSV-A lung infection in normal and immunodeficient mice, respectively, confirming that such antibodies are important and sufficient for BBG2Na-induced pulmonary protection. Our results clearly demonstrate that BBG2Na contains an important immunogenic domain of the RSV G protein. The prokaryotic origin of this protein indicates that glycosylation of the RSV G protein is not necessary for protective efficacy. Thus, BBG2Na has potential as an RSV subunit vaccine.

Peripheral vasoconstrictor responses to sympathetic activation in diabetic patients: relationship with rheological disorders

The sympathetic nervous system regulates peripheral blood flow. This study investigated sympathetic vascular control in diabetic patients by measuring cutaneous blood flow (CBF) with a laser Doppler device at rest and during three sympathetic activation tests: deep-breathing, changing positions from sitting to standing, and using the Valsalva maneuver. The influence of various factors, particularly rheological changes, was also assessed. Forty-two type II diabetes mellitus (non-insulin-dependent [NIDDM]) patients and 14 control subjects were studied. The mean value and standard deviation (SD) of basal CBF at rest were not significantly different in the two groups. In 12 NIDDM patients, the SD was less than the lowest limit found in the controls. During the three tests, the reduction in CBF and its downward slope were lower in NIDDM patients than in controls, with the greatest difference occurring during the deep-breathing test. During this test, the downward slope of CBF was less than the lowest control level in 14 NIDDM patients. The log SD of basal CBF correlated with the decrease in CBF during the sitting-to-standing and Valsalva tests in control subjects and during all three tests in NIDDM patients. In NIDDM patients, log mean basal CBF correlated negatively with the log erythrocyte filtration index ([FI] an index of rigidity) and positively with hemoglobin A1c (HbA1c). The log downward slope of CBF during the deep-breathing test correlated negatively with log erythrocyte Fl. The log downward slope of CBF during the sitting-to-standing and Valsalva tests correlated positively with total cholesterol and triglycerides, respectively. Basal CBF and the CBF response to these tests did not correlate with retinopathy, nephropathy, peripheral neuropathy, or heart rate variations during these tests. This study suggests that CBF assessment by laser Doppler flowmetry affords an attractive noninvasive way to investigate sympathetic nervous function in diabetic patients. The amplitude of changes in basal CBF and the decrease in CBF during the deep-breathing test show that this is a simple and sensitive procedure for detecting sympathetic nerve dysfunction. Moreover, theological blood properties and metabolic factors seem to strongly influence resting CBF and vasomotor reflexes.

Agent orange and the risk of gestational trophoblastic disease in Vietnam

There have been claims of an increased risk for gestational trophoblastic disease (i.e., hydatidiform mole and choriocarcinoma) in Vietnam since the period of Agent Orange sprayings. In 1990, we conducted a case-control study in Ho Chi Minh City to investigate risk factors for gestational trophoblastic disease in Vietnam. Eighty-seven married women, all of whom had a recent pathologic diagnosis of gestational trophoblastic disease, identified in the Obstetrical and Gynecological Hospital, were included in the study. Eighty-seven married women who were admitted mainly in the surgery departments of the same hospital were the controls, and they were matched to cases for age and area of residence. Odds ratios (ORs), adjusted for matching variables and other potential confounders, were estimated with unconditional logistic regression. A statistically significant trend in risk was observed with previous live births (p = .01). Cases were found to eat less meat per wk (OR = 0.4, 95% confidence interval [95% CI] = 0.2-0.9 for > or = five meat dishes) and to own fewer consumer goods than controls. An increase in risk was associated with the breeding of pigs (OR = 5.7, 95% CI = 1.2-27.6 for raising three or more pigs). A cumulative Agent Orange exposure index was constructed, using the patient's complete residence history. No significant difference was found between cases and controls for this index (OR = 0.7, 95% CI = 0.2-1.8 for high-exposure category), nor was such a difference noted for the agricultural use of pesticides.

The possible involvement of GABAA systems in the antinarcotic effect of majonoside-R2, a major constituent of Vietnamese ginseng, in mice

The effect of majonoside-R2 on morphine- and U-50,488H-induced antinociception was examined by the tail-pinch test in mice and compared with that of diazepam. Majonoside-R2 and diazepam inhibited the morphine- and U-50,488H-induced antinociception, and the actions were antagonized by the benzodiazepine receptor antagonist flumazenil and the GABA-gated CI- channel blocker picrotoxin. Diazepam but not majonoside-R2 exhibited a protective activity against convulsion caused by the GABAA antagonists bicuculline and picrotoxin. These results indicate that GABAA systems are involved in the effect of majonoside-R2 on the opioid-induced antinociception and suggest that the mechanisms of action of majonoside-R2 may differ from those of diazepam.

Surface display on staphylococci: a comparative study

Two different host-vector expression systems, designed for cell surface display of heterologous receptors on Staphylococcus xylosus and Staphylococcus carnosus, respectively, were compared for the surface display of four variants of a 101 amino acid region derived from the G glycoprotein of human respiratory syncytial virus (RSV). Surface localization of the different chimeric receptors was evaluated by a colorimetric assay and by fluorescence-activated cell sorting. It was concluded that the S. carnosus system was better both in the ability to translocate inefficiently secreted peptides and in the number of exposed hybrid receptors. The potential use of the described staphylococci as live bacterial vaccine vehicles or alternatives to filamentous phages for surface display of protein libraries is discussed.