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Biomedical subjects

J C Cox

Publications and source records attributed to J C Cox.

At least 19 recordsLinked to original sources
PubMed2001

Cytotoxic T cell polyepitope vaccines delivered by ISCOMs.

CD8 alphabeta cytotoxic T lymphocyte (CTL) polyepitope or polytope vaccines have traditionally been delivered using recombinant vector or DNA based delivery modalities. Here we show the delivery of polytope vaccines in the form of either synthetic polypeptides or recombinant polytope proteins by ImmunoStimulatory COMplexes (ISCOMs(R)). Induction of multiple protective CTL responses by these polytope-ISCOM formulations were comparable to viral vector or DNA based delivery modalities as assessed by IFNgamma ELISpot, chromium release and viral challenge assays. Measurement of CTL responses specific for the different epitopes revealed immunodominance patterns, which were largely independent of the vaccine vector or the order of the epitopes in the polytope. ISCOMs thus emerge as a viable human delivery modality for protein-based polytope vaccines.

Amino Acid Sequence↗
PubMed2001

Automated selection of anti-protein aptamers.

The in vitro selection of nucleic acid binding species (aptamers) is frequently repetitive, time-consuming, and poorly adapted to high-throughput applications. We have adapted automated workstations to select anti-protein aptamers; as an example, we demonstrated the selection of anti-lysozyme aptamers that function as efficient inhibitors of cell lysis. The increases in throughput brought about by automation should potentiate the application of aptamer technology to the rapidly growing field of proteomics.

Animals↗
PubMed2001

Paying doctors more: use of musculoskeletal specialists and increased physician pay to decrease workers' compensation costs.

Previous studies evaluating workers' compensation care systems used retrospective controls. We performed a concurrent effectiveness study comparing a WC system that used visiting musculoskeletal specialists to assist primary care physicians with a typical discounted-fee, WC, managed-care system. In the new specialist-direct system, physicians could not profit from self-referral, but were paid 35% to 69% more per patient visit than doctors in the discounted-fee clinics. All claims filed by all employees of two hotels for 2 years were examined. Patients had self-selected either a specialist-direct or a discounted-fee clinic, and the entire cost of the claim was assigned to either system of care. Claim costs were 63% lower in the specialist-direct system (P < 0.001). Medical costs were 45% less (P < 0.014), and indemnity 85% less (P < 0.001), in this system. Claims were closed nearly 6 months faster in the specialist-direct system (P < 0.0001). Indemnity claims were more common in the discounted-fee system (P < 0.0001). Claimant and injury characteristics were not significantly different between the systems. This new care model is a cost-effective alternative to discounted WC managed care. Discounting the services of the primary treating physician may result only in cost-shifting, not cost-saving.

Adult↗
PubMed2001

Toward automated nucleic acid enzyme selection.

Methods for automation of nucleic acid selections are being developed. The selection of aptamers has been successfully automated using a Biomek 2000 workstation. Several binding species with nanomolar affinities were isolated from diverse populations. Automation of a deoxyribozyme ligase selection is in progress. The process requires eleven times more robotic manipulations than an aptamer selection. The random sequence pool contained a 5' iodine residue and the ligation substrate contained a 3' phosphorothioate. Initially, a manual deoxyribozyme ligase selection was performed. Thirteen rounds of selection yielded ligators with a 400-fold increase in activity over the initial pool. Several difficulties were encountered during the automation of DNA catalyst selection, including effectively washing bead-bound DNA, pipetting 50% glycerol solutions, purifying single strand DNA, and monitoring the progress of the selection as it is performed. Nonetheless, automated selection experiments for deoxyribozyme ligases were carried out starting from either a naive pool or round eight of the manually selected pool. In both instances, the first round of selection revealed an increase in ligase activity. However, this activity was lost in subsequent rounds. A possible cause could be mispriming during the unmonitored PCR reactions. Potential solutions include pool redesign, fewer PCR cycles, and integration of a fluorescence microtiter plate reader to allow robotic 'observation' of the selections as they progress.

Automation↗
PubMed1999

The complexities of DNA computation.

Over the past few years, a handful of insightful researchers have bridged the gap between biological computing theory and actual DNA-based computation. By using ingenious encoding techniques and clever molecular-biological manipulations, simple versions of computationally complex problems have been experimentally approached or resolved. However, the technical problems revealed during the execution of these scientific set pieces make it unlikely that DNA will ever rival silicon for the solution of any real-world problem.

Algorithms↗
PubMed1998

The gain of three mitochondrial introns identifies liverworts as the earliest land plants.

The first evidence for the emergence of land plants (embryophytes) consists of mid-Ordovician spore tetrads (approximately 476 Myr old). The identity of the early plants that produced these spores is unclear; they are sometimes claimed to be liverworts, but there are no associated megafossils, and similar spores can be produced by a diversity of plants. Indeed, the earliest unequivocal megafossils of land plants consist of early vascular plants and various plants of uncertain affinity. Different phylogenetic analyses have identified liverworts, hornworts and bryophytes as each being the first lineage of land plants; the consensus of these conflicting topologies yields an unresolved polychotomy at the base of land plants. Here we survey 352 diverse land plants and find that three mitochondrial group II introns are present, with occasional losses, in mosses, hornworts and all major lineages of vascular plants, but are entirely absent from liverworts, green algae and all other eukaryotes. These results indicate that liverworts are the earliest land plants, with the three introns having been acquired in a common ancestor of all other land plants, and have important implications concerning the early stages of plant evolution.

Base Sequence↗
PubMed1998

ISCOMs: an adjuvant with multiple functions.

Aluminum salts are currently the only widely used adjuvant for human vaccines. Over the past 10-15 years, a large research effort has attempted to find novel adjuvants with ability to induce a broad range of immune responses, including cell-mediated immunity. The immunostimulating complex or ISCOM is one adjuvant with multiple adjuvant properties. ISCOMs are open cage-like complexes typically with a diameter of about 40 nm that are built up by cholesterol, lipid, immunogen, and saponins from the bark of the tree Quillaia saponaria Molina. ISCOMs have been demonstrated to promote antibody responses and induce T helper cell as well as cytotoxic T lymphocyte responses in a variety of experimental animal models, and have now progressed to phase I and II human trials. This review describes recent developments in the understanding of the structure, composition, and preparation of ISCOMs and will cover important aspects of the understanding of the adjuvant functions of ISCOMs and how they act on the immune system.

Adjuvants, Immunologic↗
PubMed1997

Adjuvants--a classification and review of their modes of action.

Since early this century, various substances have been added to vaccines and certain formulations have been devised in an attempt to render vaccines more effective. Despite a plethora of options, only aluminium salts have gained acceptance as human vaccine adjuvants and even veterinary vaccines are largely dependent upon the use of aluminium salts. Currently, many new vaccines are under development and there is a desire to simplify vaccination schedules both by increasing the number of components per vaccine and decreasing the number of doses required for a vaccine course. New, more effective adjuvants will be required to achieve this.

Adjuvants, Immunologic↗
PubMed1996

Snake envenomation in cats and its detection by rapid immunoassay.

OBJECTIVE: To determine the usefulness of a snake venom detection kit (SVDK) in the management of envenomed cats. DESIGN: A clinical study. ANIMALS: Twenty-two cats were investigated. PROCEDURE: Cats injected subcutaneously with approximately 0.25 or 1.0 lethal dose (LD) of tiger snake venom or 1 or 4 LD of brown snake venom were observed for clinical symptoms of envenomation at intervals over the ensuring 24 to 48 hours(h). Blood and urine samples were taken at regular intervals and assayed in a quantitative laboratory assay for snake venoms. Selected samples were assayed in parallel in a rapid, semi-quantitative SVDK. RESULTS: The studies showed that it was important to estimate the elapsed time from envenomation to presentation. If this time was less than 8 h, blood was the most appropriate sample and a negative result should exclude serious envenomation. If the elapsed time exceeded 8 h, it was essential that urine be sampled. Venom levels in urine were high at 8 h and approached the level of test sensitivity over 24 to 48 h; however by this time clinical signs were obvious in endangered cats. CONCLUSIONS: Careful use of the SVDK is a valuable aid in the management of a potentially envenomed cat.

Animals↗
PubMed1994

Evaluation of a novel diagnostic test for canine parvovirus.

The CPV ELISA detection kit (CSL Ltd., Melbourne Australia) was developed as a rapid field test for the detection of canine parvovirus (CPV) antigen in canine faecal samples. The kit utilises a novel concept in enzyme immunoassay (ELISA) where the conjugate is lyophilised along with the solid-phase capture antibody in the test well. The CPV ELISA was compared to the haemagglutination assay (HA) test using electron microscopy (EM) and/or virus isolation (VI) to confirm infection. The CPV ELISA had a sensitivity of 87% and a specificity of 100% compared to 87% and 63% respectively for the HA. The poor specificity of the HA results in a low positive predictive value of 51% compared to 100% for the CPV ELISA. The CPV ELISA requires no specialised equipment, is simple to perform and provides a visible result in less than 15 minutes.

Animals↗
PubMed1992

Removal of false-positive reactions from plasma in an enzyme immunoassay for bovine interferon-gamma.

A monoclonal antibody-based sandwich enzyme immunoassay (EIA) for bovine interferon-gamma (IFN-gamma) has been developed and can be used in conjunction with a whole blood culture system to diagnose tuberculosis in cattle. During its development, normal bovine plasma samples were tested to establish background levels of circulatory IFN-gamma. Of 191 samples tested, 81 (42.4%) were positive (OD > 0.1) when tested undiluted in intact monoclonal antibody (IgG1)-coated wells compared to only 8 (4.2%) in F(ab')2-coated wells, which suggested non-specific interference in the EIA rather than circulatory IFN-gamma. Reactivity of all remaining samples was removed by diluting plasmas 1/2 with 1% casein-PBS-0.05% Tween 20 supplemented with an optimum amount (5%) of normal mouse serum (NMS). Serum pools derived from BALB/c, DBA/2, C3H/HeJ, CBA/CaH and Swiss, but not C57BL/6J, mice were found to inhibit equally the reactions of five strong false-positive bovine plasma samples but had no effect on the titre of IFN-gamma in the sample. Sera from other species tested were less effective. This suggests that the interfering factors possess a high degree of specificity, since the immunoglobulin heavy chain of IgG1 produced by all these five strains of mice are allotypically identical and different to IgG1 produced by C57BL/6J mice. The use of F(ab')2 antibody fragments to coat plate wells and sample diluent containing 5% NMS has resulted in an EIA for bovine IFN-gamma that is virtually free from false-positive reactions, has a high degree of reproducibility and a sample detection limit equivalent to approximately 80 pg/ml recombinant bovine IFN-gamma.

Animals↗
PubMed1992

A novel format for a rapid sandwich EIA and its application to the identification of snake venoms.

A rapid sandwich enzyme immunoassay format is described where conjugate is lyophilised within the well in which the test reaction will occur. The format is straight forward to manufacture, has a prolonged shelf life, and eliminates one incubation and wash step from the usual test procedure. The technology has been applied to the development of a rapid assay for the identification of snake venom in clinical specimens. The resultant assay was specific and sensitive, provided rapid results and was appropriate for field use.

Immunoenzyme Techniques↗
PubMed1992

The gamma-interferon assay for diagnosis of bovine tuberculosis in cattle: conditions affecting the production of gamma-interferon in whole blood culture.

The recently developed gamma-interferon (IFN-gamma) assay system for the diagnosis of bovine tuberculosis in cattle has been accredited by the Standing Committee on Agriculture for use in Australia. In this test system, whole blood is incubated with tuberculin purified protein derivative (PPD) antigens for 16 to 24 h. The plasma is then collected and assayed for IFN-gamma production using an enzyme immunoassay (EIA). The assay system has proven to be a rapid, sensitive and inexpensive method for measuring antigen specific cell-mediated reactivity when compared with the more traditional lymphocyte proliferation assay. The IFN-gamma assay is the first in-vitro cellular assay to be used as a routine diagnostic test in veterinary medicine. While the IFN-gamma EIA has been optimised, several conditions affecting the production of IFN-gamma in whole blood culture needed investigation. We determined that optimal IFN-gamma production required the use of heparinised blood, cultured with 20 micrograms/ml of PPD within 8 h of collection. The use of blood collected post mortem resulted in reduced sensitivity for the assay. The kinetics of IFN-gamma release were established as were the effects of intradermal tuberculin testing on the IFN-gamma assay.

Animals↗
PubMed1991

A comparison of the sensitivity and specificity of enzyme immunoassays and time-resolved fluoroimmunoassay.

Time-resolved fluoroimmunoassay (TR-FIA) and various enzyme immunoassays (EIA) were compared in order to determine the detection system which showed the greatest degree of sensitivity without sacrificing specificity. The system chosen for the evaluation of these assays was the detection of antibodies to human immunodeficiency virus (HIV). For EIA, horseradish peroxidase (HRP) and alkaline phosphatase (AP) were investigated, each with a number of different substrates. HRP with its fluorogenic substrate, 3-(p-hydroxyphenyl)propionic acid (HPPA) was 1.6 times (p less than 0.01) more sensitive than with 3,3',5,5'-tetramethylbenzidine (TMB) and four times (p less than 0.001) more sensitive than with 2,2'-azino-di(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS). AP with its fluorogenic substrate, 4-methylumbelliferyl phosphate (4MeUP), was 6-7 times (p less than 0.001) more sensitive than with phenolphthalein monophosphate (PMP) and 8-13 times (p less than 0.001) more sensitive than with p-nitrophenyl phosphate (pNPP). TR-FIA with Eu3(+)-labelled anti-human IgG was equivalent in sensitivity to HRP with TMB and AP with 4MeUP.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Immunisation against ovine caseous lymphadenitis: correlation between Corynebacterium pseudotuberculosis toxoid content and protective efficacy in combined clostridial-corynebacterial vaccines.

Groups of sheep were dosed with vaccines containing Corynebacterium pseudotuberculosis toxoid combined in varying amounts with 5 clostridial antigens. Resistance of the sheep to infection with C pseudotuberculosis was tested at 1, 6 and 12 months after vaccination by infection with pus from ovine lymph glands actively infected with C pseudotuberculosis. The outcome was assessed 3 months after challenge by slaughter and inspection of the sheep for caseous lymphadenitis lesions. Protection was demonstrated by a significant reduction in the proportion of immunised sheep exhibiting lesions compared with control sheep, and by fewer abscesses in affected immunised sheep than in affected control sheep. A positive correlation was found between amount of C pseudotuberculosis toxoid administered and degree of protection obtained. Chromatographically-purified toxoid induced essentially the same protection, suggesting that anti-toxic immunity is the major factor in protection.

Animals↗
PubMed1991

Development and evaluation of a rapid absorbed enzyme immunoassay test for the diagnosis of Johne's disease in cattle.

An absorbed enzyme immunoassay (EIA) test for Johne's disease in cattle was developed in which absorption of cross-reacting antibodies occurred as a rapid reaction in solution rather than overnight with whole organisms and a subsequent centrifugation step. Total test time was reduced to less than 2 h with a minimum of manipulations. The test was evaluated in cattle herds from Johne's disease-endemic and Johne's disease-free regions of Australia. Specificity was 99.8%. Calculations of sensitivity were affected by the history of the herd under test. However, the EIA detected in excess of 80% of animals before onset of clinical disease and 65% of faecal shedders were EIA positive on, or before, first detection of Mycobacterium paratuberculosis in their faeces. The test should aid epidemiological studies and be a useful tool in the management and control of Johne's disease.

Absorption↗
PubMed1991

Evaluation of a commercial enzyme-linked immunosorbent assay for Johne's disease.

A new commercial kit for diagnosis of bovine paratuberculosis (Johne's disease), called the Johne's Absorbed EIA (enzyme immunoassay; Commonwealth Serum Laboratories, Parkville, Victoria, Australia), was evaluated by using serum specimens from the National Repository for Paratuberculosis Specimens. The evaluation was specifically designed to measure test sensitivity and specificity for detection of dairy cattle with subclinical paratuberculosis. The case definition of subclinical bovine paratuberculosis was isolation of Mycobacterium paratuberculosis from fecal samples or internal organs of cattle without diarrhea or chronic weight loss. Animals designed as free of the disease originated exclusively from four herds in Wisconsin that were certified to be free of disease. The kit had a sensitivity of 47.3% for serum specimens from 150 infected cattle. The test detected 59.7% of animals that shed M. paratuberculosis in their feces, as defined by conventional fecal culture, at the time of serum collection. Testing of 196 serum specimens from cattle without paratuberculosis yielded two false-positive results; the test specificity was thus 99.0%. Decision analysis procedures on the economics of using the kit in a test-and-cull disease control program indicated it would be cost-effective in any herd with a true paratuberculosis prevalence of greater than or equal to 3%. Comparison of the sensitivity and specificity of the Johne's Absorbed EIA with those of other tests for detection of subclinical paratuberculosis indicated that it may be the most accurate commercially available test at present and better than standard complement fixation test used in the United States.

Animals↗