Observer variability and sensitivity of radiographic diagnosis of canine medial coronoid disease.

OBJECTIVE: Medial coronoid disease (MCD) is a very common form of elbow joint disease and it's radiographic diagnosis can be challenging since it is frequently based on the detection of rather subtle primary or secondary changes than on a large primary lesion. We hypothesized that accuracy of radiographic diagnosis of MCD is highly dependent on training and experience level. METHODS: Radiographs of 102 canine elbows were evaluated for MCD by four observers with different levels of training and experience. All elbows underwent CT scans and arthroscopy. Sensitivity and specificity of radiographic and CT interpretation was determined using arthroscopy as a gold standard. Interobserver and intraobserver agreement (reliability and repeatability) were assessed by using Cohen's Kappa (κ) statistic. RESULTS: The sensitivity (92.4-96.7%) of the two experienced observers was almost comparable to that of CT (100%) and significantly higher than that of the two less experienced observers (77.2-80.4%). Reliability of the radiographic diagnosis of MCD was better between observers with higher experience level (κ= 0.74) than between observers of lower or different experience levels (κ=0.07-0.42). Repeatability was better in experienced (κ= 0.73-0.88) than in less experienced observers (κ= 0.31-0.42). CONCLUSION: Our results confirm that training and experience play important roles in reaching high sensitivity, reliability and repeatability for the radiographic diagnosis of MCD. CLINICAL RELEVANCE: Although radiography is inferior to CT in imaging of the medial coronoid process itself, sensitivity of radiographic diagnosis MCD can be significantly improved with observer experience almost reaching that of CT. Therefore, it is advised that radiographic screening for MCD should be performed by specialists experienced in the radiographic evaluation of elbow joint disease.

[Diagnostic value of CT and MRI for the diagnosis of coronoid pathology in the dog]. / Diagnostische Wertigkeit von Computertomographie und Magnetresonanztomographie für die Diagnose einer Koronoiderkrankung beim Hund.

OBJECTIVE: The diagnostic value of CT and MRI regarding the diagnosis of coronoid pathology in the dog. MATERIAL AND METHODS: Computed tomography (CT) and magnetic resonance imaging (MRI) of the elbow joint were performed in dogs with clinical and radiological signs of coronoid pathology. Afterwards, all dogs underwent arthroscopic surgery. For the computed tomographic examination, a 16-slice-CT-scanner spiral-CT (Philips Brilliance 16) was used. The MRI-examination was performed with a 1-Tesla superconducting magnet (Phillips Intera 1.0). T1 and T2 weighted images with different sequences were acquired. RESULTS: In total, 44 elbow joints from 44 patients (total of 12 breeds, including mixed breeds) were examined. The most represented breeds were Labrador Retrievers (38.6%, n=17), mixed breed dogs (22.7%, n=10) and Golden Retrievers (11.4%, n=5) were represented most. The age of the 30 male dogs (68%) and 14 female dogs (32%) ranged from 6 to 117 months (mean 2.25 years). Using CT, the following results could be evaluated: a) fissure at the level of the Processus coronoideus medialis ulnae (PCM) in 66% (n=29); b) fragments at the level of the PCM in 55% (n=24); c) deformation at the level of the PCM in all 44 joints; d) increased opacity at the level of the base of the PCM in all 44 joints; e) heterogenous opacity at the apex of the PCM in 91% (n=41). With MRI, the following results could be evaluated: a) fissure at the level of the PCM in 59% (n=26); b) fragments at the level of the PCM in 57% (n=25); c) deformation at the level of the PCM in 86% (n=38); d) increased opacity at the level of the base of the PCM, thus making assessment impossible; e) heterogenous opacity at the apex of the PCM, thus making assessment impossible. CONCLUSION AND CLINICAL RELEVANCE: Both diganostic imaging modalities are appropriate for evaluating coronoid pathology in the dog.

Accelerated photobleaching of a cyanine dye in the presence of a ternary target DNA, PNA probe, dye catalytic complex: a molecular diagnostic.

In many settings, molecular testing is needed but unavailable due to complexity and cost. Simple, rapid, and specific DNA detection technologies would provide important alternatives to existing detection methods. Here we report a novel, rapid nucleic acid detection method based on the accelerated photobleaching of the light-sensitive cyanine dye, 3,3'-diethylthiacarbocyanine iodide (DiSC(2)(3) I(-)), in the presence of a target genomic DNA and a complementary peptide nucleic acid (PNA) probe. On the basis of the UV-vis, circular dichroism, and fluorescence spectra of DiSC(2)(3) with PNA-DNA oligomer duplexes and on characterization of a product of photolysis of DiSC(2)(3) I(-), a possible reaction mechanism is proposed. We propose that (1) a novel complex forms between dye, PNA, and DNA, (2) this complex functions as a photosensitizer producing (1)O(2), and (3) the (1)O(2) produced promotes photobleaching of dye molecules in the mixture. Similar cyanine dyes (DiSC(3)(3), DiSC(4)(3), DiSC(5)(3), and DiSC(py)(3)) interact with preformed PNA-DNA oligomer duplexes but do not demonstrate an equivalent accelerated photobleaching effect in the presence of PNA and target genomic DNA. The feasibility of developing molecular diagnostic assays based on the accelerated photobleaching (the smartDNA assay) that results from the novel complex formed between DiSC(2)(3) and PNA-DNA is under way.

Autoimmunity to deltaNp63alpha in chronic ulcerative stomatitis.

Chronic ulcerative stomatitis (CUS) is a recently described mucocutaneous condition in which patients experience chronic, painful, ulcerative lesions of the oral mucosa. CUS is diagnosed by immunofluorescence studies that demonstrate antinuclear antibodies. These autoantibodies are specific for a protein, deltaNp63alpha, which is normally expressed in basal cell nuclei of stratified squamous epithelia. The purpose of this study was to characterize the autoimmune response in CUS. Protein antigens were produced by in vitro transcription/translation of polymerase chain-reaction (PCR)-amplified cDNAs. We used immunoblotting and immunoprecipitation experiments with serum from CUS patients to examine the (1) antibody isotype, (2) immunogenic functional domains of the deltaNp63alpha antigen, and (3) cross-reactivity with homologous p53, p73, and p63 proteins. Results demonstrate CUS patient antibodies to deltaNp63alpha, and 52% of cases have circulating IgA isotype antibodies. The N-terminal and DNA-binding domains are the immunodominant regions, and antibody cross-reactivity with p53, p63, and p73 isoforms is limited.

Antigen selection from an HIV-1 immune antibody library displayed on yeast yields many novel antibodies compared to selection from the same library displayed on phage.

Phage display of antibody libraries has been widely used for over a decade to generate monoclonal antibodies. Yeast display has been developed more recently. Here the two approaches were directly compared using the same HIV-1 immune scFv cDNA library expressed in phage and yeast display vectors and using the same selecting antigen (HIV-1 gp120). Yeast display was shown to sample the immune antibody repertoire considerably more fully than phage display, selecting all the scFv identified by phage display and twice as many novel antibodies. Positive phage display selection appeared to largely reflect those antibodies that as phage-scFv gave the highest signal in phage ELISAs assessing antigen binding. This signal is thought to reflect the efficiency of expression of folded scFv at the phage surface. Increased access to immune repertoires may increase the rescue of novel antibodies of therapeutic or analytical value that often form a minor part of a typical antibody response.

Filamentous phage as an immunogenic carrier to elicit focused antibody responses against a synthetic peptide.

Filamentous bacteriophage are widely used as immunogenic carriers for "phage-displayed" recombinant peptides. Here we report that they are an effective immunogenic carrier for synthetic peptides. The f1.K phage was engineered to have an additional Lys residue near the N-terminus of the major coat protein, pVIII, so as to enhance access to chemical cross-linking agents. The dimeric synthetic peptide, B2.1, was conjugated to f1.K (f1.K/B2.1) in high copy number and compared as an immunogen to B2.1 conjugated to ovalbumin (OVA/B2.1) and to phage-displayed, recombinant B2.1 peptide. All immunogens were administered without adjuvant. The serum antibody titers were measured against: the peptide, the carrier, and, if appropriate, the cross-linker. All immunogens elicited anti-peptide antibody titers, with those elicited by OVA/B2.1 exceeding those by f1.K/B2.1; both titers were greater than that elicited by recombinant B2.1 phage. Comparison of the anti-peptide and anti-carrier antibody responses showed that f1.K/B2.1 elicited a more focused anti-peptide antibody response than OVA/B2.1. The anti-peptide antibody response against f1.K/B2.1 was optimized for the injection route, dose and adjuvant. Dose and adjuvant did not have a significant effect on anti-peptide antibody titers, but a change in injection route from intraperitoneal (IP) to subcutaneous (SC) enhanced anti-peptide antibody titers after seven immunizations. The optimized anti-peptide antibody response exceeded the anti-carrier one by 21-fold, compared to 0.07-fold elicited by OVA/B2.1. This indicates that phage as a carrier can focus the antibody response against the peptide. The results are discussed with respect to the advantages of phage as an alternative to traditional carrier proteins for synthetic peptides, carbohydrates and haptens, and to further improvements in phage as immunogenic carriers.

High-throughput variation detection and genotyping using microarrays.

The genetic dissection of complex traits may ultimately require a large number of SNPs to be genotyped in multiple individuals who exhibit phenotypic variation in a trait of interest. Microarray technology can enable rapid genotyping of variation specific to study samples. To facilitate their use, we have developed an automated statistical method (ABACUS) to analyze microarray hybridization data and applied this method to Affymetrix Variation Detection Arrays (VDAs). ABACUS provides a quality score to individual genotypes, allowing investigators to focus their attention on sites that give accurate information. We have applied ABACUS to an experiment encompassing 32 autosomal and eight X-linked genomic regions, each consisting of approximately 50 kb of unique sequence spanning a 100-kb region, in 40 humans. At sufficiently high-quality scores, we are able to read approximately 80% of all sites. To assess the accuracy of SNP detection, 108 of 108 SNPs have been experimentally confirmed; an additional 371 SNPs have been confirmed electronically. To access the accuracy of diploid genotypes at segregating autosomal sites, we confirmed 1515 of 1515 homozygous calls, and 420 of 423 (99.29%) heterozygotes. In replicate experiments, consisting of independent amplification of identical samples followed by hybridization to distinct microarrays of the same design, genotyping is highly repeatable. In an autosomal replicate experiment, 813,295 of 813,295 genotypes are called identically (including 351 heterozygotes); at an X-linked locus in males (haploid), 841,236 of 841,236 sites are called identically.

Neutralization synergy of human immunodeficiency virus type 1 primary isolates by cocktails of broadly neutralizing antibodies.

Several reports have described the existence of synergy between neutralizing monoclonal antibodies (MAbs) against human immunodeficiency virus type 1 (HIV-1). Synergy between human MAbs b12, 2G12, 2F5, and 4E10 in neutralization of primary isolates is of particular interest. Neutralization synergy of these MAbs, however, has not been studied extensively, and the mechanism of synergy remains unclear. We investigated neutralization synergy among this human antibody set by using the classical approach of titrating antibodies mixed at a fixed ratio as well as by an alternative, variable ratio approach in which the neutralization curve of one MAb is assessed in the presence and absence of a fixed, weakly neutralizing concentration of a second antibody. The advantage of this second approach is that it does not require mathematical analysis to establish synergy. No neutralization enhancement of any of the MAb combinations tested was detected for the T-cell-line-adapted molecular HIV-1 clone HxB2 using both assay formats. Studies of primary isolates (89.6, SF162, and JR-CSF) showed neutralization synergy which was relatively weak, with a maximum of two- to fourfold enhancement between antibody pairs, thereby increasing neutralization titers about 10-fold in triple and quadruple antibody combinations. Analysis of b12 and 2G12 binding to oligomeric envelope glycoprotein by using flow cytometry failed to demonstrate cooperativity in binding between these two antibodies. The mechanism by which these antibodies synergize is, therefore, not yet understood. The results lend some support to the notion that an HIV-1 vaccine that elicits moderate neutralizing antibodies to multiple epitopes may be more effective than hereto supposed, although considerable caution in extrapolating to a vaccine situation is required.

Broadly neutralizing antibodies targeted to the membrane-proximal external region of human immunodeficiency virus type 1 glycoprotein gp41.

The identification and epitope mapping of broadly neutralizing anti-human immunodeficiency virus type 1 (HIV-1) antibodies (Abs) is important for vaccine design, but, despite much effort, very few such Abs have been forthcoming. Only one broadly neutralizing anti-gp41 monoclonal Ab (MAb), 2F5, has been described. Here we report on two MAbs that recognize a region immediately C-terminal of the 2F5 epitope. Both MAbs were generated from HIV-1-seropositive donors, one (Z13) from an antibody phage display library, and one (4E10) as a hybridoma. Both MAbs recognize a predominantly linear and relatively conserved epitope, compete with each other for binding to synthetic peptide derived from gp41, and bind to HIV-1(MN) virions. By flow cytometry, these MAbs appear to bind relatively weakly to infected cells and this binding is not perturbed by pretreatment of the infected cells with soluble CD4. Despite the apparent linear nature of the epitopes of Z13 and 4E10, denaturation of recombinant envelope protein reduces the binding of these MAbs, suggesting some conformational requirements for full epitope expression. Most significantly, Z13 and 4E10 are able to neutralize selected primary isolates from diverse subtypes of HIV-1 (e.g., subtypes B, C, and E). The results suggest that a rather extensive region of gp41 close to the transmembrane domain is accessible to neutralizing Abs and could form a useful target for vaccine design.

Overexpression of GDNF induces and maintains hyperinnervation of muscle fibers and multiple end-plate formation.

This study examined the role of glial cell line-derived neurotrophic factor (GDNF) in synaptic plasticity at the developing neuromuscular junction. Transgenic mice overexpressing GDNF in skeletal muscle under the myosin light chain-1 promoter were isolated. Northern blot and ELISA at 6 weeks of age indicated that GDNF mRNA and protein levels were elevated threefold in the lateral gastrocnemius muscle (LGM) of the GDNF-transgenic animals. Histochemical examination of LGM tissue sections at 6 weeks of age revealed a 70% increase in the number of cholinesterase-positive end plates without changes in end-plate area. Multiple end plates on a single muscle fiber were also observed, in addition to multiple axonal processes terminating on individual end plates. No change in the number of spinal motoneurons, overall LGM size, or muscle type composition was observed. Finally, overexpression of GDNF in muscle caused hypertrophy of neuronal somata in dorsal root ganglia without affecting their number. These findings demonstrate that overexpression of a single neurotrophic factor in skeletal muscle induces multiple end-plate formation and maintains hyperinnervation well beyond the normal developmental period. We suggest that GDNF, a muscle-derived motoneuron neurotrophic factor, serves an important role in the regulation of synaptic plasticity in the developing and adult neuromuscular junction.

Crystal structure of a neutralizing human IGG against HIV-1: a template for vaccine design.

We present the crystal structure at 2.7 angstrom resolution of the human antibody IgG1 b12. Antibody b12 recognizes the CD4-binding site of human immunodeficiency virus-1 (HIV-1) gp120 and is one of only two known antibodies against gp120 capable of broad and potent neutralization of primary HIV-1 isolates. A key feature of the antibody-combining site is the protruding, finger-like long CDR H3 that can penetrate the recessed CD4-binding site of gp120. A docking model of b12 and gp120 reveals severe structural constraints that explain the extraordinary challenge in eliciting effective neutralizing antibodies similar to b12. The structure, together with mutagenesis studies, provides a rationale for the extensive cross-reactivity of b12 and a valuable framework for the design of HIV-1 vaccines capable of eliciting b12-like activity.

Identification and characterization of a peptide that specifically binds the human, broadly neutralizing anti-human immunodeficiency virus type 1 antibody b12.

Human monoclonal antibody (MAb) b12 recognizes a conformational epitope that overlaps the CD-4-binding site of the human immunodeficiency virus type 1 (HIV-1) envelope. MAb b12 neutralizes a broad range of HIV-1 primary isolates and protects against primary virus challenge in animal models. We report here the discovery and characterization of B2.1, a peptide that binds specifically to MAb b12. B2.1 was selected from a phage-displayed peptide library by using immunoglobulin G1 b12 as the selecting agent. The peptide is a homodimer whose activity depends on an intact disulfide bridge joining its polypeptide chains. Competition studies with gp120 indicate that B2.1 occupies the b12 antigen-binding site. The affinity of b12 for B2.1 depends on the form in which the peptide is presented; b12 binds best to the homodimer as a recombinant polypeptide fused to the phage coat. Originally, b12 was isolated from a phage-displayed Fab library constructed from the bone marrow of an HIV-1-infected donor. The B2.1 peptide is highly specific for b12 since it selected only phage bearing b12 Fab from this large and diverse antibody library.

Distribution and sequence analysis of the centromere-associated repetitive element CEN38 of Sorghum bicolor (Poaceae).

Fluorescence in situ hybridization (FISH) of a large-insert genomic clone, BAC 22B2, previously suggested that Sorghum bicolor (2n = 20) has the tetraploid architecture A(b)A(b)B(b)B(b). Here, we report on BAC 22B2 subclone pCEN38 (1047-bp insert) as related to sorghum and sugarcane. Mitotic FISH of six different subclones of BAC 22B2 showed that pCEN38 produced the strongest specificity to the A(b) subgenome and signal occurred primarily near centromeres. Southern blots of pCEN38 to 21 crop plants revealed a narrow taxonomic distribution. Meiotic metaphase I FISH positioned pCEN38 sequences near active centromeres. Pachytene FISH revealed that the distributions are trimodal in several B(b) and possibly all sorghum chromosomes. DNA sequencing revealed that the pCEN38 fragment contains three tandemly repeated dimers (<280 bp) of the same sequence family found in sorghum clone pSau3A10, and that each dimer consists of two divergent monomers (<140 bp). Sequence comparisons revealed homology between the pCEN38 monomers and the SCEN 140 bp tandem repeat family of sugarcane. FISH of pCEN38 yielded signal in centromere regions of most but not all sugarcane chromosomes. Results suggest that sugarcane and sorghum share at least one ancestor harboring elements similar to pCEN38 and SCEN and that each species had an ancestor in which the repetitive element was weakly present or lacking.

Resolution of Ga-67 citrate uptake in the left neck mass of Hodgkin's disease and reversion of double scoliosis of cervical-thoracic and lower lumbar vertebrae.

A 6-yr-old boy underwent a total body Ga-67 citrate imaging study because of a large mass of Hodgkin's lymphoma in the left neck and the left anterior chest wall region. The images showed intense uptake in the left neck extending anteroinferiorly to the left upper chest wall corresponding to the left neck and chest region. In addition, there was mild cervical-upper thoracic scoliosis with convexity to the right and mild scoliosis of the lower lumbar scoliosis with concavity to the left. After three cycles of chemotherapy, in the follow-up Ga-67 citrate total body images seven months after his first Ga-67 citrate imaging, the intense uptake in the left neck and the left upper chest wall had been resolved and the scoliosis of the cervical-thoracic and lower lumbar spine had also been reversed to normal. This case shows that a Ga-67 citrate imaging study is useful for first diagnosis and subsequent monitoring of the therapeutic effects in a follow-up imaging. Also Ga-67 citrate imaging provided evidence that the scoliosis had been reversed.

Urinary extravasation and leakage after renal transplantation: a case report.

OBJECTIVE: This case report illustrates urinary extravasation and leakage after renal transplantation, as documented by nuclear medicine renal imaging. The extravasation and leakage were identified only on images acquired after the patient voided. The surgical wound site dressings were found to contain radioactive contamination as well.

Homodimeric peptides displayed by the major coat protein of filamentous phage.

Peptide libraries displayed by filamentous bacteriophage have proven a powerful tool for the discovery of novel peptide agonists, antagonists and epitope mimics. Most phage-displayed peptides are fused to the N terminus of either the minor coat protein, pIII, or the major coat protein, pVIII. We report here that peptides containing cysteine residues, displayed as N-terminal fusions to pVIII, can form disulfide-bridged homodimers on the phage coat. Phage clones were randomly selected from libraries containing one or two fixed Cys residues, and surveyed for the presence of peptide-pVIII homodimers by SDS-PAGE analysis that involved pretreatment of the phage with reducing or thiol-modifying agents. For all phage whose recombinant peptide contained a single Cys residue, a significant fraction of the peptide-pVIII molecules were displayed as dimers on the phage coat. The dimeric form was in greater abundance than the monomer in almost all cases in which both forms could be reliably observed. Occasionally, peptides containing two Cys residues also formed dimers. These results indicate that, for a given pVIII-displayed peptide bearing a single Cys residue, a significant fraction of the peptide (>40 %) will dimerize regardless of its sequence; however, sequence constraints probably determine whether all of the peptide will dimerize. Similarly, only occasionally do peptides bearing two Cys residues form intermolecular disulfide bridges instead of intramolecular ones; this indicates that sequence constraints may also determine dimerization versus cyclization. Sucrose-gradient analysis of membranes from cells expressing pVIII fused to a peptide containing a single Cys residue showed that dimeric pVIII is present in the cell prior to its assembly onto phage. A model of the peptide-pVIII homodimer is discussed in light of existing models of the structure and assembly of the phage coat. The unique secondary structures created by the covalent association of peptides on the phage surface suggest a role for homo- and heterodimeric peptide libraries as novel sources of bioactive peptides.

Ty1-copia-retrotransposon behavior in a polyploid cotton.

Retrotransposons constitute a ubiquitous and dynamic component of plant genomes. Intragenomic and intergenomic comparisons of related genomes offer potential insights into retrotransposon behavior and genomic effects. Here, we have used fluorescent in-situ hybridization to determine the chromosomal distributions of a Ty1-copia-like retrotransposon in the cotton AD-genome tetraploid Gossypium hirsutum and closely related putative A- and D-genome diploid ancestors. Retrotransposon clone A108 hybridized to all G. hirsutum chromosomes, approximately equal in intensity in the A- and D-subgenomes. Similar results were obtained by hybridization of A108 to the A-genome diploid G. arboreum, whereas no signal was detected on chromosomes of the D-genome diploid G. raimondii. The significance and potential causes of these observations are discussed.

Patterns of genetic variation in Mendelian and complex traits.

This review discusses the prospects for understanding the genetic basis of complex traits in humans. We take the view that work done on Drosophila melanogaster can serve as a model for understanding complex traits in humans, and the literature on this model system, as well as on humans, is reviewed. The prospects for success in understanding the genetic basis of complex traits depend, in part, on the nature of the forces acting on genetic variation. We suggest that different experimental approaches should be undertaken for traits caused by common genetic variants versus those arising from rare genetic variants.

Genetic variation in rates of nondisjunction: association of two naturally occurring polymorphisms in the chromokinesin nod with increased rates of nondisjunction in Drosophila melanogaster.

Genetic variation in nondisjunction frequency among X chromosomes from two Drosophila melanogaster natural populations is examined in a sensitized assay. A high level of genetic variation is observed (a range of 0.006-0.241). Two naturally occurring variants at the nod locus, a chromokinesin required for proper achiasmate chromosome segregation, are significantly associated with an increased frequency of nondisjunction. Both of these polymorphisms are found at intermediate frequency in widely distributed natural populations. To account for these observations, we propose a general model incorporating unique opportunities for meiotic drive during female meiosis. The oötid competition model can account for both high mean rates of female-specific nondisjunction in Drosophila and humans as well as the standing genetic variation in this critical fitness character in natural populations.

Classic Weinstein: tetrad analysis, genetic variation and achiasmate segregation in Drosophila and humans.

A maximum-likelihood method for the estimation of tetrad frequencies from single-spore data is presented. The multilocus exchange with interference and viability (MEIV) model incorporates a clearly defined model of exchange, interference, and viability whose parameters define a multinomial distribution for single-spore data. Maximum-likelihood analysis of the MEIV model (MEIVLA) allows point estimation of tetrad frequencies and determination of confidence intervals. We employ MEIVLA to determine tetrad frequencies among 15 X chromosomes sampled at random from Drosophila melanogaster natural populations in Africa and North America. Significant variation in the frequency of nonexchange, or E(0) tetrads, is observed within both natural populations. Because most nondisjunction arises from E(0) tetrads, this observation is quite unexpected given both the prevalence and the deleterious consequences of nondisjunction in D. melanogaster. Use of MEIVLA is also demonstrated by reanalyzing a recently published human chromosome 21 dataset. Analysis of simulated datasets demonstrates that MEIVLA is superior to previous methods of tetrad frequency estimation and is particularly well suited to analyze samples where the E(0) tetrad frequency is low and sample sizes are small, conditions likely to be met in most samples from human populations. We discuss the implications of our analysis for determining whether an achiasmate system exists in humans to ensure the proper segregation of E(0) tetrads.