CpG DNA functions as an effective adjuvant for the induction of immune responses in aged mice

The present studies demonstrate that the immunization of aged mice with Diphtheria toxoid in formulations containing unmethylated immunostimulatory CpG motifs, promotes the successful development of immune responses that are qualitatively and quantitatively comparable to those induced in young animals vaccinated in a similar manner. Aged mice given vaccines containing CpG oligodeoxynucleotides (ODNs) expressed primary and secondary systemic humoral immune responses having isotype profiles consistent with an enhancement in Th-1 type immunity. The ability to generate common mucosal immunity was also restored in aged animals given CpG ODN-containing vaccines. Dendritic cells (DCs) were determined to represent one of the cellular targets of CpG ODN activities in aged mice since restoration of immune function was observed when DCs from aged donors were pulsed with antigen and CpG ODNs, prior to injection into syngeneic young adult or aged recipients. Interestingly, antigen-pulsed DCs from young donors were fully capable of stimulating immune responses following their injection into syngeneic young adult or aged hosts, without a need for exposure to CpG ODNs. Although the mechanism(s) by which CpG DNA exerts its beneficial adjuvant effects on the aged immune system remains unclear, our findings suggest that the incorporation of CpG ODNs into vaccine formulations provided to the aged could prove useful in the development of more effective vaccines for the elderly.

Development of surface plasmon resonance-based immunoassay for aflatoxin B(1)

Aflatoxins are a group of highly toxic fungal secondary metabolites that occur in Aspergillus species and may contaminate foodstuffs and feeds. Two different anti-aflatoxin B(1) antibodies were examined to develop a surface plasmon resonance (SPR)-based immunoassay to aflatoxin B(1). A conjugate consisting of aflatoxin B(1)-bovine serum albumin (BSA) was immobilized on the dextran gel surface. Competition between immobilized aflatoxin B(1) conjugate and free aflatoxin B(1) in solution for binding to antibody injected over the surface formed the basis for the assay. Regeneration of the antibody from the immobilized conjugate surface is essential for the development of such an inhibitive immunoassay. Problems were encountered with the regeneration of the sensor surface, due to the high-affinity binding of the antibodies. Conventional regeneration solutions consisting of low concentrations of NaOH and HCl worked to a degree, but regeneration was at the expense of the integrity of the immobilized conjugate. A polyclonal anti-aflatoxin B(1) antibody was produced and was found to be regenerable using an organic solution consisting of 1 M ethanolamine with 20% (v/v) acetonitrile, pH 12.0. This combined high ionic strength and extreme pH, as well as chaotrophic properties and allowed the development of an inhibitive immunoassay. The assay had a linear range of 3.0-98.0 ng mL(-1) with good reproducibility.

Use of phosphonic acid as a generic hapten in the production of broad specificity anti-organophosphate pesticide antibody

Phosphonic acid (trans-4-phosphono-2-butenic acid; TPB) was used as a generic hapten in order to generate broad specificity antibodies against a group of organophosphorus pesticides. The polyclonal antiserum showed, in an indirect enzyme-linked immunosorbent assay (ELISA) format, preferential binding toward pesticides containing unsaturated diethyl-phosphate functionalities rather than the equivalent thiophosphate or dimethyl structures. The level of detection in the ELISA using a heterologous system was investigated and showed a 20-fold improvement when a conjugate for which the antibody had lower affinity was immobilized on the plate. Biosensor assays using parathion as a standard indicated that the antibody had a relatively high dissociation rate, and reproducible cycles of regeneration were achieved. The potential for using TPB as a generic hapten is discussed.

Identification of novel mutations in the ryanodine-receptor gene (RYR1) in malignant hyperthermia: genotype-phenotype correlation

Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle that is triggered in genetically predisposed individuals by common anesthetics and muscle relaxants. The ryanodine receptor (RYR1) is mutated in a number of MH pedigrees, some members of which also have central core disease (CCD), an inherited myopathy closely associated with MH. Mutation screening of 6 kb of the RYR1 gene has identified four adjacent novel mutations, C6487T, G6488A, G6502A, and C6617T, which result in the amino acid alterations Arg2163Cys, Arg2163His, Val2168Met, and Thr2206Met, respectively. Collectively, these mutations account for 11% of MH cases and identify the gene segment 6400-6700 as a mutation hot spot. Correlation analysis of the in vitro contracture-test data available for pedigrees bearing these and other RYR1 mutations showed an exceptionally good correlation between caffeine threshold and tension values, whereas no correlation was observed between halothane threshold and tension values. This finding has important ramifications for assignment of the MH-susceptible phenotype, in genotyping studies, and indicates that assessment of recombinant individuals on the basis of caffeine response is justified, whereas assessment on the basis of halothane response may be problematic. Interestingly, the data suggest a link between the caffeine threshold and tension values and the MH/CCD phenotype.

Detection of a novel mutation at amino acid position 614 in the ryanodine receptor in malignant hyperthermia

Malignant hyperthermia (MH) is a potentially fatal autosomal dominant disorder of skeletal muscle and is triggered in susceptible people by all commonly used inhalation anaesthetics and depolarizing neuromuscular blocking agents. To date, eight mutations in the skeletal muscle ryanodine receptor gene (RYR1) have been identified in malignant hyperthermia susceptible (MHS) and central core disease (CCD) cases. We have screened the RYR1 gene in affected individuals for novel MHS mutations by single stranded conformational polymorphism (SSCP) analysis and have identified a G to T transition mutation which results in the replacement of a conserved arginine (Arg) at position 614 with a leucine (Leu). The Arg614Leu mutation was present in three unrelated MHS individuals of 151 investigated. The mutation was not detected in 148 normal chromosomes and segregated precisely with MHS in family members from one of the probands where DNA was available for analysis. This mutation occurs at the same position as the previously identified Arg to Cys mutation reported in all cases of porcine MH and in approximately 5% of human MH. A comparison of the phenotypes of the Arg614Leu and Arg614Cys probands is presented.

Coordinating DNA replication to produce one copy of the genome requires genes that act in ubiquitin metabolism

We have developed a genetic screen of the yeast Saccharomyces cerevisiae to identify genes that act to coordinate DNA replication so that each part of the genome is copied exactly once per cell cycle. A mutant was recovered in this screen that accumulates aberrantly high DNA contents but does not complete a second round of synthesis. The mutation principally responsible for this phenotype is in the DOA4 gene, which encodes a ubiquitin hydrolase, one of several yeast genes that encode enzymes that can remove the signalling polypeptide ubiquitin hydrolase, one of several yeast genes that encode enzymes that can remove the signaling polypeptide ubiquitin from its covalently linked conjugated forms. DOA4 is nonessential, and deleting this gene causes uncoordinated replication. Overreplication does not occur in cells with limiting amounts of Cdc7 protein kinase, suggesting that entry into S phase is required for this phenotype. The DNA formed in doa4 mutants is not highly unusual in the sense that mitotic recombination rates are normal, implying that a high level of repair is not induced. The temperature sensitivity of doa4 mutations is partially suppressed by extra copies of the polyubiquitin gene UB14, but overreplication still occurs in the presence of this suppressor. Mutations in DOA4 cause loss of the free ubiquitin pool in cells under heat stress conditions, and extra copies of UB14 restore this pool without restoring coordination of replication. We conclude that a ubiquitin-mediated signaling event directly involving the ubiquitin hydrolase encoded by DOA4 is needed in S. cerevisiae to prevent uncoordinated DNA replication.

Detection of a novel RYR1 mutation in four malignant hyperthermia pedigrees

Malignant hyperthermia (MH) is a potentially fatal autosomal dominant disorder of skeletal muscle and is triggered in susceptible people by all commonly used inhalational anaesthetics and depolarizing muscle relaxants. To date, six mutations in the skeletal muscle ryanodine receptor gene (RYR1) have been identified in malignant hyperthermia susceptible (MHS) and central core disease (CCD) cases. Using SSCP analysis, we have screened the RYR1 gene in affected individuals for novel MHS mutations and have identified a G to A transition mutation which results in the replacement of a conserved Gly at position 2433 with an Arg. The Gly2433Arg mutation was present in four of 104 unrelated MHS individuals investigated and was not detected in a normal population sample. This mutation is adjacent to the previously identified Arg2434His mutation reported in a CCD/MH family and indicates that there may be a second region in the RYR1 gene where MHS/CCD mutations cluster.

Mutation screening of the RYR1 gene in malignant hyperthermia: detection of a novel Tyr to Ser mutation in a pedigree with associated central cores

The ryanodine receptor gene (RYR1) has been shown to be mutated in a small number of malignant hyperthermia (MH) pedigrees. Missense mutations in this gene have also been identified in two families with central core disease (CCD), a rare myopathy closely associated with MH. In an effort to identify other RYR1 mutations responsible for MH and CCD, we used a SSCP approach to screen the RYR1 gene for mutations in a family exhibiting susceptibility to MH (MHS) where some of the MHS individuals display core regions in their muscle. Sequence analysis of a unique aberrant SSCP has allowed us to identify a point mutation cosegregating with MHS in the described family. The mutation changes a conserved tyrosine residue at position 522 to a serine residue. This mutation is positioned relatively close to five of the six MHS/CCD mutations known to date and provides further evidence that MHS/CCD mutations may cluster in the amino terminal region of the RYR1 protein.

Detection of a novel common mutation in the ryanodine receptor gene in malignant hyperthermia: implications for diagnosis and heterogeneity studies

Malignant hyperthermia (MH) is a potentially fatal autosomal dominant disorder of skeletal muscle and is triggered in susceptible people by all commonly used inhalational anaesthetics. To date, the ryanodine receptor gene (RYR1) has been shown to be mutated in a small number of malignant hyperthermia susceptible (MHS) cases. To determine if a common RYR1 mutation exists that might account for a significant number of MHS cases, we have investigated the RYR1 gene in unrelated patients for the presence of new mutations by the single-stranded conformation polymorphism method and have identified a novel Gly341Arg mutation which accounts for approximately 10% of Caucasian MHS cases. The implications of this common mutation in MHS diagnosis and heterogeneity studies are discussed.

Mutations in the ryanodine receptor gene in central core disease and malignant hyperthermia

Central core disease (CCD) of muscle is an inherited myopathy which is closely associated with malignant hyperthermia (MH) in humans. CCD has recently been shown to be tightly linked to the ryanodine receptor gene (RYR1) and mutations in this gene are known to be present in MH. Mutation screening of RYR1 has led to the identification of two previously undescribed mutations in different CCD pedigrees. One of these mutations was also detected in an unrelated MH pedigree whose members are asymptomatic of CCD. The data suggest a model to explain how a single mutation may result in two apparently distinct clinical phenotypes.