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C P Quinn

Publications and source records attributed to C P Quinn.

At least 19 recordsLinked to original sources
PubMed2006

Analysis of anti-protective antigen IgG subclass distribution in recipients of anthrax vaccine adsorbed (AVA) and patients with cutaneous and inhalation anthrax.

The anti-PA IgG1, IgG2, IgG3, and IgG4 subclass responses to clinical anthrax and to different numbers of anthrax vaccine adsorbed (AVA, BioThrax) injections were determined in a cross-sectional study of sera from 63 vaccinees and 13 clinical anthrax patients. The data show that both vaccination with three AVA injections and clinical anthrax elicit anti-PA IgG1, IgG2, and IgG3 subclass responses. An anti-PA IgG4 response was detected in AVA recipients after the fourth injection. The anthrax lethal toxin (LTx) neutralization efficacy of sera from recipients who received 4 to > or =10 AVA injections did not vary significantly in relation to changes in distribution of anti-PA IgG1 and IgG4 subclasses.

Adult↗
PubMed2005

Simultaneous measurement of specific serum IgG responses to five select agents.

Select Agents are defined by CDC and the USDA Animal and Plant Health Inspection Service (APHIS) as biological agents or toxins deemed a threat to public, animal, or plant health, or to animal or plant products. They are classified on the basis of their ease of dissemination, mortality/morbidity rate, and potential for social disruption. A subset of these agents includes Bacillus anthracis, Yersinia pestis, Francisella tularensis, ricin toxin (RT), and staphylococcal enterotoxin B (SEB). Infection or intoxication with these agents has been shown to elicit an antigen-specific serum IgG response. We describe a fluorescent covalent microsphere immunoassay (FCMIA) for measurement of specific IgG antibodies to seven different antigens from five different select agents; B. anthracis [protective antigen (PA) and lethal factor (LF)], Y. pestis (F1 and V antigens), F. tularensis, RT and SEB simultaneously in human B. anthracis vaccinee sera (containing anti-PA and anti-LF IgG) which had been spiked with animal specific IgG antibodies to the other select agents. Inter-assay and intra-assay coefficients of variation were 6.5 and 13.4%, respectively (N = 4). There were no significant differences (P > 0.70) between assay responses when the assays were performed individually or multiplexed. When the observed versus expected interpolated concentrations were compared, highly linear relationships were observed (r2 values from 0.981 to 0.999, P < 0.001). Minimum detectable concentrations (MDC) ranged from 0.3 ng mL(-1) (Y. pestis F1) to 300 ng mL(-1) (RT). Finally, the curves showed responses were linear for most analytes from their MDC to 125 (SEB) to 1,300 (Y. pestis F1) x their MDC. These data indicate that multiplexed FCMIA is a sensitive and accurate method for simultaneous measurement of specific IgG in serum to CDC select agents and may be of value in screening either decontamination workers or the general population for exposure to/infection with these agents.

Animals↗
PubMed2005

Immunogenicity of recombinant protective antigen and efficacy against aerosol challenge with anthrax.

Immunization with a recombinant form of the protective antigen (rPA) from Bacillus anthracis has been carried out with rhesus macaques. Rhesus macaques immunized with 25 mug or more of B. subtilis-expressed rPA bound to alhydrogel had a significantly increased immunoglobulin G (IgG) response to rPA compared with macaques receiving the existing licensed vaccine from the United Kingdom (anthrax vaccine precipitated [AVP]), although the isotype profile was unchanged, with bias towards the IgG1 and IgG2 subclasses. Immune macaque sera from all immunized groups contained toxin-neutralizing antibody and recognized all the domains of PA. While the recognition of the N terminus of PA (domains 1 to 3) was predominant in macaques immunized with the existing vaccines (AVP and the U.S. vaccine anthrax vaccine adsorbed), macaques immunized with rPA recognized the N- and C-terminal domains of PA. Antiserum derived from immunized macaques protected macrophages in vitro against the cytotoxic effects of lethal toxin. Passive transfer of IgG purified from immune macaque serum into naive A/J mice conferred protection against challenge with B. anthracis in a dose-related manner. The protection conferred by passive transfer of 500 mug macaque IgG correlated significantly (P = 0.003; r = 0.4) with the titers of neutralizing antibody in donor macaques. Subsequently, a separate group of rhesus macaques immunized with 50 mug of Escherichia coli-derived rPA adsorbed to alhydrogel was fully protected against a target dose of 200 50% lethal doses of aerosolized B. anthracis. These data provide some preliminary evidence for the existence of immune correlates of protection against anthrax infection in rhesus macaques immunized with rPA.

Administration, Intranasal↗
PubMed2004

Mass value assignment of total and subclass immunoglobulin G in a human standard anthrax reference serum.

An anti-Anthrax Vaccine Adsorbed (anti-AVA) standard human reference serum pool, AVR414, has been prepared, and the total and protective antigen (PA)-specific immunoglobulin G (IgG) were quantified. AVR414 was prepared by plasmapheresis of healthy adults who had received a minimum of four subcutaneous injections of AVA. Mass values (in milligrams per milliliter) for total IgG and IgG subclasses 1 to 4 were determined by radial immunodiffusion. Anti-PA-specific IgG assignment (in micrograms per milliliter) was done by consensus of two complementary approaches: homologous enzyme-linked immunosorbent assay (ELISA) with affinity-purified anti-PA IgG as a calibrator and summation of mean PA-specific IgG subclass concentrations determined by IgG subclass-specific ELISA using the United States National Reference Preparation for Human Serum Proteins as a standard. The total IgG concentration assigned to AVR414 reference serum was 8.33 mg/ml. IgG subclass concentrations were the following: for IgG1, 4.48 mg/ml; for IgG2, 3.35 mg/ml; for IgG3, 0.37 mg/ml; and for IgG4, 0.30 mg/ml. The assigned mass value for total anti-PA-specific IgG was 141.2 microg/ml. Anti-PA-specific IgG subclass concentrations were the following: for IgG1, 79.6 microg/ml; for IgG2, 35.3 microg/ml; for IgG3, 3.2 microg/ml; and for IgG4, 25.3 microg/ml. Human reference serum pool AVR414 will have direct application in the standardization of anthrax serological assays, in reagent qualification, and as a standard for quantification of PA-specific IgG in humans who have been vaccinated with or otherwise exposed to Bacillus anthracis PA.

Anthrax Vaccines↗
PubMed2002

Novel in vitro functional assays for the determination of anthrax toxin components.

The characterisation and evaluation of the UK licensed human anthrax vaccine depends on several in vivo tests that determine its safety and potency. Assays for the determination of functionally active and/or immunoreactive toxin components and S-layer proteins have been developed and applied to the characterisation of anthrax vaccine. These technologies may support production of consistent and effective vaccines, and may ultimately reduce the requirements for in vivo testing.

Adenylyl Cyclases↗
PubMed2001

Clostridium botulinum neurotoxins act with a wide range of potencies on SH-SY5Y human neuroblastoma cells.

We have described, in undifferentiated SH-SY5Y human neuroblastoma cells, the relative potency of Clostridium botulinum neurotoxin (BoNT) serotypes A-F Sensitivity of stimulated [3H]-noradrenaline ([3H]-NA) release to the toxins had a rank order of potency of: C > D > A > B > F after 3 days exposure. The difference between the most potent (BoNT/C: IC50 0.54 nM) and the least (BoNT/F: IC50 > 300 nM) was approximately 1,000-fold. Though fluid phase endocytosis may have been the mechanism of entry for low potency toxins the far higher potency of BoNT/C would suggest receptor-driven entry. Potency was not a reflection of the dependence of the release mechanism on a particular SNARE since the substrate specificities were mixed throughout the potency order. This indicated that the toxins differed in their efficiency of binding/endocytosis or enzymatic activity inside the cell. The serotypes that cleaved vesicle-associated membrane protein (VAMP) isoforms (BoNT/B, D and F) did not fully inhibit [3H]-NA release. Cleavage of the appropriate substrate proteins was observed for all serotypes. SNAP-25 cleavage by BoNT/A was shown to be a dose-dependent and correlated closely with reduction of release, supporting proteolysis as the mechanism by which toxin inhibited secretion. Comparison of the SH-SY5Y cell line sensitivity to BoNT/A with glycine releasing rat primary spinal cord neuron cultures, revealed a massive difference in potency; the primary cultures being approximately 200,000-fold more sensitive. The demonstration, using BoNTs, of the crucial role of SNAP-25, VAMP and syntaxin in SH-SY5Y cells suggests the use of this neuroblastoma as a model in the study of these proteins in neurotransmitter release.

Animals↗
PubMed2000

Inhibition of vesicular secretion in both neuronal and nonneuronal cells by a retargeted endopeptidase derivative of Clostridium botulinum neurotoxin type A.

Clostridial neurotoxins potently and specifically inhibit neurotransmitter release in defined cell types by a mechanism that involves cleavage of specific components of the vesicle docking/fusion complex, the SNARE complex. A derivative of the type A neurotoxin from Clostridium botulinum (termed LH(N)/A) that retains catalytic activity can be prepared by proteolysis. The LH(N)/A, however, lacks the putative native binding domain (H(C)) of the neurotoxin and is thus unable to bind to neurons and effect inhibition of neurotransmitter release. Here we report the chemical conjugation of LH(N)/A to an alternative cell-binding ligand, wheat germ agglutinin (WGA). When applied to a variety of cell lines, including those that are ordinarily resistant to the effects of neurotoxin, WGA-LH(N)/A conjugate potently inhibits secretory responses in those cells. Inhibition of release is demonstrated to be ligand mediated and dose dependent and to occur via a mechanism involving endopeptidase-dependent cleavage of the natural botulinum neurotoxin type A substrate. These data confirm that the function of the H(C) domain of C. botulinum neurotoxin type A is limited to binding to cell surface moieties. The data also demonstrate that the endopeptidase and translocation functions of the neurotoxin are effective in a range of cell types, including those of nonneuronal origin. These observations lead to the conclusion that a clostridial endopeptidase conjugate that can be used to investigate SNARE-mediated processes in a variety of cells has been successfully generated.

Animals↗
PubMed2000

A conjugate composed of nerve growth factor coupled to a non-toxic derivative of Clostridium botulinum neurotoxin type A can inhibit neurotransmitter release in vitro.

Nerve growth factor (NGF) receptor binding, internalisation and transportation of NGF has been identified as a potential route of delivery for other molecules. A derivative of Clostridium botulinum neurotoxin type A (LHN) that retains catalytic activity but has significantly reduced cell-binding capability has been prepared and chemically coupled to NGF. Intact clostridial neurotoxins potently inhibit neurotransmitter release at the neuromuscular junction by proteolysis of specific components of the vesicle docking/fusion complex. Here we report that the NGF-LHN/A conjugate, when applied to PC12 cells, significantly inhibited neurotransmitter release and cleaved the type A toxin substrate. This work represents the successful use of NGF as a targeting moiety for the delivery of a neurotoxin fragment.

Animals↗
PubMed1999

The native virulence plasmid combination affects the segregational stability of a theta-replicating shuttle vector in Bacillus anthracis var. New Hampshire.

The segregational stability of a small, theta-replicating, non-mobilizable shuttle plasmid (pAEX-5E) was determined in fully virulent (pX01+/pX02+), partially cured (pX01+/pX02- and pX01-/pX02+) and fully cured (pX01-/pX02-) derivatives of Bacillus anthracis var. New Hampshire. Under the growth conditions used (L-broth, 37 degrees C, aerobic, batch culture), pAEX-5E remained segregationally stable in the pX01-/pX02+ and pX01-/pX02- derivatives for in excess of 100 culture generations, but was expelled from the pX01+/pX02+ and pX01+/pX02- derivatives (100% loss occurred after 101+/-3.8 and 54+/-6.0 culture generations, respectively). In the presence of antibiotic selection pressure to maintain pAEX-5E (5 microg erythromycin ml-1) no comparable loss of pX01 or pX02 was observed over 100 generations of growth in any of the derivatives of B. anthracis. Under these conditions the pX01+/pX02- derivative had an extended culture doubling time (td+/-S. E. of the mean) of 75.3 +/- 1.4 min compared with 47.3 +/- 1.1, 46.2 +/- 0.86 and 43.2 +/- 1.2 min for the pX01+/pX02+, pX01-/pX02+ and pX01-/pX02- derivatives, respectively. That antibiotic resistance was pAEX-5E-mediated was confirmed using a second antibiotic marker (kanamycin). After100 generations of growth in the presence of erythromycin, colonies were shown to have retained kanamycin resistance. Southern blot analysis, in conjunction with plasmid rescue to Escherichia coli confirmed that, after 100 culture generations in the presence of antibiotic selection pressure, pAEX-5E had remained structurally stable and had not integrated into the B. anthracis genome.

Animals↗
PubMed1998

Continuous amperometric monitoring of glucose in a brittle diabetic chimpanzee with a miniature subcutaneous electrode.

The performance of an amperometric biosensor, consisting of a subcutaneously implanted miniature (0.29 mm diameter, 5 x 10(-4) cm2 mass transporting area), 90 s 10-90% rise/decay time glucose electrode, and an on-the-skin electrocardiogram Ag/AgCl electrode was tested in an unconstrained, naturally diabetic, brittle, type I, insulin-dependent chimpanzee. The chimpanzee was trained to wear on her wrist a small electronic package and to present her heel for capillary blood samples. In five sets of measurements, averaging 5 h each, 82 capillary blood samples were assayed, their concentrations ranging from 35 to 400 mg/dl. The current readings were translated to blood glucose concentration by assaying, at t = 1 h, one blood sample for each implanted sensor. The rms error in the correlation between the sensor-measured glucose concentration and that in capillary blood was 17.2%, 4.9% above the intrinsic 12.3% rms error of the Accu-Chek II reference, through which the illness of the chimpanzee was routinely managed. Linear regression analysis of the data points taken at t>1 h yielded the relationship (Accu-Chek) = 0. 98 x (implanted sensor) + 4.2 mg/dl, r2 = 0.94. The capillary blood and the subcutaneous glucose concentrations were statistically indistinguishable when the rate of change was less than 1 mg/(dl. min). However, when the rate of decline exceeded 1.8 mg/(dl.min) after insulin injection, the subcutaneous glucose concentration was transiently higher.

Animals↗
PubMed1996

Statistics for critical clinical decision making based on readings of pairs of implanted sensors.

Low error rates are essential if lives of patients are to depend on readings of implanted sensors, such as glucose sensors in insulin-dependent diabetic patients. To verify the operation and to calibrate on demand an implanted sensor, it is necessary that calibration through a single, independent measurement involving withdrawal of only one sample of blood and its independent analysis be feasible. Such a one-point calibration must be accurate. Borrowing from nuclear reactor safety assurance, where a likelihood ratio test is applied to readings of pairs of pressure sensors for shutdown/no shutdown decisions, we apply a similar test to sensor pairs implanted in rats. We show, for five sets of glucose sensor pairs, calibrated in vivo by withdrawal of a single sample of blood, that application of the likelihood ratio test increases the fraction of the clinically correct readings from 92.4% for their averaged readings to 98.8%.

Algorithms↗
PubMed1996

Crystal structure of a biologically inactive mutant of toxic shock syndrome toxin-1 at 2.5 A resolution.

Toxic shock syndrome toxin-1 (TSST-1) is one of a family of staphylococcal exotoxins recognized as microbial superantigens. The toxin plays a dominant role in the genesis of toxic shock in humans through a massive activation of the immune system. This potentially lethal illness occurs as a result of the interaction of TSST-1 with a significant proportion of the T-cell repertoire. TSST-1, like other superantigens, can bind directly to class II major histocompatibility (MHC class II) molecules prior to its interaction with entire families of V beta chains of the T-cell receptor (TCR). The three-dimensional structure of a mutant (His-135-Ala) TSST-1 was compared with the structure of the native (wild-type) TSST-1 at 2.5 A resolution. The replacement of His 135 of TSST-1 with an Ala residue results in the loss of T-cell mitogenicity and toxicity in experimental animals. This residue, postulated to be directly involved in the toxin-TCR interactions, is located on the major helix alpha 2, which forms the backbone of the molecule and is exposed to the solvent. In the molecular structure of the mutant toxin, the helix alpha 2 remains unaltered, but the His to Ala modification causes perturbations on the neighboring helix alpha 1 by disrupting helix-helix interactions. Thus, the effects on TCR binding of the His 135 residue could actually be mediated, wholly or in part, by the alpha 1 helix.

Bacterial Toxins↗
PubMed1995

Photo-crosslinked copolymers of 2-hydroxyethyl methacrylate, poly(ethylene glycol) tetra-acrylate and ethylene dimethacrylate for improving biocompatibility of biosensors.

A copolymer containing 88% 2-hydroxyethyl methacrylate (HEMA), 9% poly(ethylene glycol) (MW 18.5 kDa) tetra-acrylate and 3% ethylene dimethacrylate was prepared and evaluated for use as a biocompatible interface between glucose biosensors and tissue in the rat. The glucose sensor utilizes glucose oxidase that is electrically 'wired' to a gold current collector by a reduction-oxidation polymer. Coatings of the copolymer were crosslinked in situ on the sensors using long wavelength ultraviolet light and 2,2-dimethoxy-2-phenyl-acetophenone as the initiator. The effect these films had on the current response to glucose was measured. Over a glucose concentration range of 0-30 mM, the average percentage decrease in response was 45 +/- 28% (mean +/- 95% confidence interval) at 37 degrees C for films that were about 0.1 mm thick, an acceptable value. Copolymer-treated and control electrodes were implanted in the intrascapular subcutaneous tissue of male Sprague-Dawley rats for three days. The explanted samples were evaluated using scanning electron microscopy. The control electrodes were highly encapsulated with fibrous material, while the copolymer-treated electrodes induced much less encapsulation. The results show this copolymer to be a candidate as a biocompatible coating for electrically wired oxidoreductase-based subcutaneous biosensors.

Acrylates↗
PubMed1995

Kinetics of glucose delivery to subcutaneous tissue in rats measured with 0.3-mm amperometric microsensors.

The time between intravenous injection of a glucose bolus and the time the glucose concentration peaked in the subcutaneous tissue was measured in pentobarbital-anesthetized rats with implanted 290-microns-diameter amperometric sensors. Boluses of 100, 200, and 400 mg/kg body wt were injected. The glucose concentration in the jugular vein was monitored by frequent withdrawal and analysis of samples. The glucose concentration in the subcutaneous tissue was continuously monitored with the sensors. The times required for the subcutaneously implanted sensor to reach its maximum current, corrected for sensor response times, were 7.5 +/- 3.9, 9.8 +/- 5.5, and 10.0 +/- 4.4 min for the smallest to the largest dose, respectively. The shorter delay in response to the smallest dose was statistically significant (P < 0.03). The results were consistent with dilution of the bolus in the cardiovascular system and transport of glucose by both diffusion and facilitated transport via a saturable mediator. An understanding of the differences in the dynamics of venous vs. subcutaneous response to a glucose dose is important in developing algorithms for the control of blood glucose based on a subcutaneous measurement.

Animals↗
PubMed1994

Design, characterization, and one-point in vivo calibration of a subcutaneously implanted glucose electrode.

A 0.29-mm-diameter flexible electrode designed for subcutaneous in vivo amperometric monitoring of glucose is described. The electrode was designed to allow "one-point" in vivo calibration, i.e., to have zero output current at zero glucose concentration, even in the presence of other electroreactive species of serum or blood. A valid zero point, along with a measurement of the glucose concentration in a withdrawn sample of blood at which the current is known, defined the sensitivity in the linear response range. The electrode was four-layered, with the layers serially deposited within a 0.125-mm recess upon the tip of a polyimide-insulated 0.25-mm gold wire. The recessed structure reduced the sensitivity to movement and allowed, through control of the depth of the recess, control of the transport of glucose and thus the range of linearity. The recess contained the four polymeric layers, with a total mass less than 5 micrograms and no leachable components. The bottom glucose concentration-to-current transducing layer consisted of the enzyme "wiring" redox polymer poly[(vinylimidazole)Os(bipyridine)2Cl]+ , complexed with recombinant glucose oxidase and cross-linked with poly(ethylene glycol) diglycidyl ether, to form an electron-conducting hydrogel. The layer was overcoated with an electrically insulating layer of polyaziridine-cross-linked poly(allylamine), on which an immobilized interference-eliminating horseradish peroxidase based film was deposited. An outer biocompatible layer was formed by photo-cross-linking derivatized poly(ethylene oxide). The current output of a typical electrode at 10 mM glucose and at 37 degrees C was 35 nA, the apparent Km was 20 mM, and the 10-90% response time was approximately 1 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Polyimide-polyethylene glycol block copolymers: synthesis, characterization, and initial evaluation as a biomaterial.

Block copolyimides with varying amounts of polyethylene glycol (PEG) were synthesized and characterized by copolymerization of diaminodiphenyl ether (DDE), amino terminated PEG, and benzophenone tetracarboxylic acid dianhydride (BTDA). Strong materials were obtained, with enhanced flexibility as compared to the parent DDE-BTDA polyimide homopolymer. Incorporation of PEG led to an increase in water absorption by these copolymers, and hydrophilicity was increased as reflected by a decrease in air-water-polymer contact angle. These materials supported less cell adhesion in vitro than the parent polyimide homopolymer. Short term in vivo evaluation of these copolymers showed reduced fibrous encapsulation than was observed in the absence of PEG.

Cell Adhesion↗
PubMed1993

Proteolytic cleavage of synthetic fragments of vesicle-associated membrane protein, isoform-2 by botulinum type B neurotoxin.

Recent data suggest that botulinum type-B neurotoxin is a protease which acts on vesicle-associated membrane protein, isoform 2 (VAMP-2). In this report, botulinum type-B neurotoxin is shown to cleave a synthetic fragment (HV62) of VAMP-2, corresponding to the bulk of the hydrophilic domain (amino acids 33-94). The neurotoxin acts at a single site between Gln76 and Phe77. Little or no proteolytic activity by botulinum type-B neurotoxin was observed with peptides containing 7, 10 or 20 amino acids spanning the site of cleavage. The proteolytic action of neurotoxin was strongly inhibited by EDTA and o-phenanthroline whereas captopril and phosphoramidon were ineffective. A series of model peptide substrates were synthesised in order to define the smallest VAMP-2 fragment to be cleaved by botulinum type-B neurotoxin. Data obtained from these substrates suggest that the neurotoxin belongs to a novel class of zinc-endoprotease; more than 12 amino acid residues are required on both the NH2- and COOH-terminal side of the cleavage site for optimal proteolytic activity. The results demonstrate that no other components of cellular vesicles are required for the specific action of the neurotoxin on VAMP-2. The data further show that the highly specific action of the neurotoxin is not dictated solely by the properties of the amino acid residues at the cleavage site but is also dependent on amino acid sequences distal to its site of action.

Amino Acid Sequence↗