Biological markers to establish a relationship between the health status of the St. Lawrence River yellow perch (Perca flavescens) with a gradient of anthropogenic disturbances.

Since the mid-1990s, the decline of the yellow perch population of Lake Saint-Pierre (hereinafter LSP) in Quebec, Canada has been the subject of several research programs. The combined effect of habitat deterioration, the presence of invasive species, and poor water quality negatively affected the yellow perch population in this lake. In 2013, we sampled yellow perch (larvae, juveniles and adults) at six sites along the St. Lawrence River representing a gradient of increasing human influences from upstream to downstream and measured several biomarkers including retinoid compounds (vitamin A). In the most contaminated sites (LSP, north and south shores), we found that retinoid stores were decreased in all three stages of development. To corroborate these results and to test other biomarkers, we once again sampled yellow perch (adults only) from the same sites. Results from our 2014 and 2015 samplings confirmed that LSP yellow perch appeared to be at a disadvantage compared to fish from upstream populations. Individuals from LSP have lower acetylcholinesterase (AChE) activity as well as lower retinoid levels in liver and plasma. These fish were also marked by lower levels of antioxidants such as lycopene and vitamin E. A discriminant analysis of this set of results confirmed that the yellow perch of the LSP could be easily discriminated from those of the other sites (2014 and 2015) on the basis of liver retinoid and, to a lesser extent, of the liver tocopherol and protein concentration of the muscle, as well as AChE activity and DROH (all-trans-3,4-dehydroretinol) measured in plasma.

Germline diversity of the expressed BALB/c VhJ558 gene family.

Although the mouse immunoglobulin heavy chain (Igh) locus contains 15 heavy chain V (Vh) gene families, at least half of the Vh gene segments are members of the VhJ558 family. This large Vh gene family represents the least characterized germline coding regions of any of the mouse antigen receptor loci and the contribution of individual VhJ558 genes to the preimmune repertoire is poorly understood. In fact, relatively few germline VhJ558 sequences have been reported for BALB/c, the foundation strain for mouse immunoglobulin genetics and the prototypic strain of the Igh(a) haplotype. Here we present a database consisting of 66 sequences estimated to represent one-half of the total number of functional BALB/c VhJ558 genes. Our results indicate that a subset of the VhJ558 genes is highly expressed in the preimmune repertoire, with just nine Vh sequences accounting for nearly 50% of the VhJ558 heavy chains expressed by splenic B cells. We show that this disparity in the expressed Vh gene repertoire is not due to the position of the Vh genes relative to the Dh cluster or to multiple germline copies of the highly expressed VhJ558 genes. Together, these data constitute the first detailed analysis of functional BALB/c VhJ558 genes, demonstrate a striking bias in the use of particular VhJ558 genes in the preimmune repertoire, and provide sufficient information to study the regulation of the Dh-distal region of the Igh-V locus at the level of individual genes.

Germline structure and differential utilization of Igha and Ighb VH10 genes.

Ab heavy chains encoded by mouse VH10 genes have been of particular interest due to their frequent association with DNA binding. We reported previously that VH10 sequences are over-represented in the preimmune repertoire considering the apparent number of germline-encoded VH10 gene segments. In this report, we show that the VH10 family consists of three and two germline genes in the Igha and Ighb haplotypes, respectively. The complete nucleotide sequences of these five genes, including promoters and recombination signal sequences, were determined and allow unambiguous assignment of allelic relationships. The usage of individual VH10 genes varied significantly and ranged from 0.2% to an extraordinary 7.2% of the VH genes expressed by splenic B cells. Since the promoter and recombination signal sequence elements of all five VH10 genes are identical, we suggest that the few amino acid differences encoded by these five germline VH10 genes determine their representation in the preimmune repertoire. Rearrangements of the most frequently used VH10 gene have an apparent bias for histidine at position 95 of complementarity-determining region-3 (CDR3). These CDR3s are also biased for asparagine, an amino acid associated with the CDRs of DNA binding Abs. Together, these results suggest that high VH10 gene use is the result of B cell receptor-mediated selection and may involve DNA and/or ligands that share antigenic features with DNA.

Registration and geometric modelling of the spine during scoliosis surgery: a comparison study of different pre-operative reconstruction techniques and intra-operative tracking systems.

During scoliosis instrumentation surgery, it is difficult for surgeons fully to track vertebral motion in 3D, because only the posterior elements of the spine are exposed. Different intra-operative modelling approaches are evaluated using a registration technique that matches intra-operative measurements with a 3D pre-operative model of the spine. Two tracking systems (magnetic digitiser and mechanical arm) and two pre-operative reconstruction techniques (multiplanar radiography and CT scan) are sequentially combined to build four intra-operative models. Their accuracy is assessed by comparison with the pre-operative geometry. The most minimally invasive approach (multiplanar radiographic reconstruction and magnetic digitiser) has an accuracy of 5.9 mm in translation, and errors on vertebral rotations are 4.4 degrees, 6.7 degrees and 5.0 degrees in the frontal, sagittal and transverse planes, respectively. With CT scan reconstruction, the accuracy is significantly increased by about 2 mm in translation and as much as 4.5 degrees for vertebral rotations in the sagittal plane. For the mechanical arm, the accuracy is increased by less than 1 mm in translation and 1 degree for vertebral rotations. CT scan is the most accurate reconstruction technique, but its use for long spinal segments is generally not allowed because of the high radiation exposure. Multiplanar radiographic reconstruction may be an alternative solution for long spinal segments when great accuracy is not necessary. Considering the small increase in accuracy and its awkwardness, the use of the mechanical arm may not be appropriate during surgical manoeuvres.

Accessibility changes across the mouse Igh-V locus during B cell development.

During their development, B and T lymphocytes are thought to undergo several cycles of chromatin remodeling at their antigen receptor loci that serve to regulate access of a common V(D)J recombinase to particular gene segments. We used germ-line transcription and susceptibility to DNasel as markers to examine tissue and stage-specific changes in chromatin structure surrounding genes of the VHJ558, VH10, and VHS107 families, whose members are located at discreet subregions of the locus. Germ-line VH transcripts from all three families were detectable at pro- and pre-B cell stages. Transcripts from the VH10 and VHS107 families, but not VHJ558, remained detectable at the immature and mature B cell stages. Unexpectedly, none of the germ-line VH loci examined were markedly nuclease sensitive, regardless of cell type or transcriptional activity. A modest degree of nuclease sensitivity was noted at the VHJ558 loci of pro-B and pre-B cells, however. Our data suggest that the entire Igh-V locus becomes accessible at early B cell stages, and returns thereafter to an inaccessible state. However, the timing of these accessibility changes does not occur uniformly across the VH array. These results imply that multiple long-range elements are involved in targeting VH genes for rearrangement.

Rearrangement and selection in the developing Vkappa repertoire of the mouse: an analysis of the usage of two Vkappa gene segments.

Detailed analysis of the rearrangement and expression of two mouse Vkappa genes has been used to examine B cell repertoire development. The Vkappa1-A gene is used by a large proportion (9.6%) of splenic B cells in the adult primary repertoire, whereas the Vkappa22 gene is used at a much lower frequency (0.16%). Consistent with these results, quantitative PCR (Q-PCR) assays revealed that the number of splenic B cells with rearranged Vkappa1-A genes is much greater than the number with rearranged Vkappa22 genes. Q-PCR was also performed on both normal bone marrow pre-B cells and transformed pre-B cells induced to rearrange their kappa loci at high frequency. In contrast to splenic B cell rearrangements, the numbers of Vkappa1-A and Vkappa22 rearrangements in pre-B cells differ by only two- or threefold, suggesting that the intrinsic rearrangement frequencies of these two Vkappa genes are not significantly different. Further evidence of disproportionate selection was obtained by comparing the percentages of productive rearrangements amplified from genomic splenic DNA. Sequence analysis showed 84% (37 of 44) of the Vkappa1-A rearrangements but only 57% (29 of 51) of the Vkappa22 rearrangements to be in-frame. Together these results suggest that B cells expressing Vkappa1-A-encoded light chains are preferentially selected either in the periphery or in the transition from pre-B to B cell. Sequence data also reveal a surprisingly restricted diversity of VJ junctions, apparently due to biases introduced by the rearrangement mechanism.

Differential antigen recognition by T cell populations from strains of mice developing polar forms of granulomatous inflammation in response to eggs of Schistosoma mansoni.

In humans, infection with schistosome helminths can lead to dissimilar forms of clinical disease. Likewise, in the experimental mouse system, identical infection protocols with Schistosoma mansoni cause a more severe granulomatous disease in the C3H strain than in the C57BL/6 strain. To address this difference, we developed panels of schistosomal egg antigen (SEA)-specific T cell hybridomas to compare the responses of C3H and C57BL/6 mice to the major egg antigen p40. All derived C3H T cell hybridomas, despite being clonally distinct and restricted by either I-Ak or I-Ek, responded to recombinant fragment 15-1 of the p40 antigen, while none of the C57BL/6 T cell hybridomas did. Consistent with the observed monoclonal T cell responses, polyclonal lymph node cells from schistosome-infected C3H mice reacted strongly to fragment 15-1, which contrasted sharply with the weak response displayed by the C57BL/6 strain. Moreover, studies with congenic mice demonstrated that the strong CD4+ T cell response to fragment 15-1 was under major histocompatibility complex control and segregated with the H-2k haplotype. These findings suggest that a dominant T cell response against a major egg antigen may represent a risk factor for the development of severe disease.

[Evaluation of peroperative measurement system in the follow-up of vertebral displacements]. / Evaluation d'un système de mesures per-opératoires pour le suivi de déplacements vertébraux.

A computer assisted surgery system has been developed to quantify the vertebral displacements induced by the Cotrel-Dubousset instrumentation and to visualize in 3-D the spine at different per-operative steps. This spinal surgery is realized to correct idiopathic scoliosis. Per-operative measurements are obtained by using a magnetic digitizer. Five points per thoracic vertebra and six points per lumbar vertebra are digitized. The method proposed estimates the location of the digitized points on a computer graphics 3-D model of vertebrae by a point-to-surface matching algorithm. The 3-D models are constructed before the surgery using multiplanar radiographic reconstruction technique (2 or 3 views) and geometric modeling methods. Computer tools permit the 3-D visualization of the spine peroperatively and the evaluation of clinical indices such as Cobb angles and vertebral rotations. The system includes 3 principal error sources: 2) reconstruction error; 2) digitizer error (digitizer precision) and 3) point-to-surface matching error. In order to validate the overall system, measurements have been simulated for 2 vertebrae and 2 digitizers of different precision, taking onto account the reconstruction error. For 5 and 6 digitized points per vertebra, the matching algorithm gives a RMS error of respectively 3.0 and 2.0 mm.

Deletional mapping of fifteen mouse VH gene families reveals a common organization for three Igh haplotypes.

In addition to the content of germ-line variable gene segments, the organization of V genes has been implicated in the development of the Ab repertoire. We have searched the expressed VH genes of BALB/c mice for additional VH gene families and utilized deletion mapping to explore the extent of VH gene family interspersion. We have identified and characterized one new VH gene family (VH15) and extended our previous studies of the Igha and Ighb haplotypes to include a third haplotype (Ighj) using a newly developed panel of pre-B cell lines (CXCB cell lines). We conclude that the Igha, Ighb, and Ighj haplotypes have a similar Igh-V locus structure. A refined deletional map for 15 VH gene families and an individual member of the VHSM7 family (H10) has been constructed based on the deletion profiles of 72 rearranged heavy chain loci. These results demonstrate previously unrecognized examples of interspersion among members of the VHS107, VH10, and VHSM7 families.

Computer-assisted pedicle screw fixation. A feasibility study.

STUDY DESIGN: We evaluated a computer-assisted surgical tool for inserting pedicle screws. OBJECTIVES: This study reviewed the feasibility, usefulness, and accuracy of the proposed tool. SUMMARY OF BACKGROUND DATA: Reviews documented neurovascular damage caused by screw misplacement. Currently, screw hole position is assessed by radiologic means and curette palpation. METHODS: Three sheep vertebrae and one artificial object were reconstructed three-dimensionally from computed tomography scan slices. At surgery, the surgeon's movements were displayed relative to the three-dimensional vertebrae on a computer screen. The tool was used to detect pedicles and to verify the position of drilled holes. In our laboratory, we calculated the system's accuracy by taking measurements on the artificial object. RESULTS: All pedicles were identified with the computer. Five of the six drilled hole positions were correctly represented. An accuracy of 4.5 mm +/- 1.1 mm RMS (root of the mean squared) and 1.6 degrees +/- 1.2 degrees were calculated. CONCLUSIONS: Results suggested the proposed system could be useful for pedicle detection and assessing the intravertebral location of a drilled hole. The proposed system could be used for many different orthopedic procedures where structures are hidden from the surgeon's view.

The utilization of individual VH exons in the primary repertoire of adult BALB/c mice.

The utilization of VH gene families is severely biased during fetal development, such that D-region proximal VH genes are overrepresented. After birth the VH repertoire becomes more equally representative of the total inherited set of functional VH genes. To investigate the extent of this normalization process, we have determined the relative utilization of individual VH exons in the pre-immune repertoire of adult BALB/c spleen cells. Large samples of IgM heavy chain transcripts from polyclonally activated B cells were captured in a cDNA phage library and screened by hybridization using highly specific oligonucleotide probes. These studies revealed that the utilization of particular VH exons can differ by an order of magnitude. Significantly, the VH genes most under-represented in the pre-immune repertoire are located in the region of the Igh locus most distal to the DjhCh region. We suggest that the chromosomal position of a particular VH gene may influence its utilization and that the normalization of the adult repertoire is incomplete.

Junctional diversification in the generation of the precursor of a discrete immune response.

Phosphocholine (PC)-specific antibodies that arise in the mouse in response to Proteus morganii (PM) and use V1-DFL16.1-JH1 are characterized by a number of recurring mutations. Most striking is an invariant A for G substitution in codon 95 of VH which results in an asparagine instead of aspartate at that position. Because of the apparent importance of this substitution in an anti-PC(PM) response, we wanted to determine the molecular basis for this base change. A cDNA library derived from pre-immune splenic B cells was examined for the frequency of VDJ containing the A substitution at 95 and the presence of additional point mutations in these sequences. Six different cDNA were isolated which contained an A substitution at the VD junction (frequency 0.00009); a seventh positive cDNA could not be examined. The V segments of four of these cDNA matched known germline genes and were, therefore, unmutated. Two others closely matched V in families whose members have not all been characterized, hence, it is not known whether the mutations observed are somatic or germline in origin. Sequences of 35 cDNA clones, containing the same V segment but differing in D, J and junctional nucleotides, revealed no mutations. These results indicate that the A substitution generated at codon 95 is most likely a product of V-DJ joining.

The cell-mediated response to schistosomal antigens at the clonal level: development and characterization of a panel of egg antigen-specific murine T cell clones.

The cellular basis of the immune response underlying the granulomatous hypersensitivity in experimental murine schistosomiasis caused by Schistosoma mansoni was investigated by examining a panel of 16 egg antigen-specific T cell clones. The clones were derived from a sensitized T cell line by limiting dilution, and were selected on the basis of their strong responses against schistosomal egg antigens. By cytofluorographic analysis, it was determined that all clones were T helper cells and expressed the CD3+CD4+CD8- phenotype. Lymphokine analysis revealed that some clones secreted either interleukin (IL)-2 or IL-4, but a surprisingly large number were double producers. Southern blot analysis verified the clonality of these T cells and indicated that the clones examined included at least five independent clones by the criterion of T cell receptor beta gene rearrangements. Despite their diversity, the clones responded strongly, and virtually exclusively, to egg antigen components with isoelectric points in the limited range of 4.7 to 5.2. The relevant antigenic egg molecules were shown to require processing by accessory cells for presentation to, and stimulation of, the T cell clones.

The Ig VH repertoire of fetal liver-derived pre-B cells is influenced by the expression of a gene linked to X-linked immune deficiency.

Ig VH repertoire differences between normal and x-linked immune deficiency- (xid) expressing mice are well established. To test the hypothesis that such differences might exist as early as the pre-B stage of ontogeny we generated panels of xid fetal liver derived Abelson murine leukemia virus transformants with H chain Ig VDJ rearrangements. Cells from CBA/Tufts.xid mice used VH genes from many families, with no demonstrable preference for 3' genes. Analysis of cells derived from (CBA/Tufts.xid X CBA/Tufts)F1 mice showed preferential usage of 3' family genes in the phenotypically normal females, even though V to DJ joins were made in vivo. The defective male mice did not show this marked preferential usage. A similar, but less marked, effect on VH gene usage was seen in mice with X-linked immune deficiency and a BALB/c background. Taken together, these results show that either X-linked immune deficiency, or a closely linked gene, affects fetal pre-B cells such that the usual pattern of predominant usage of 3' family genes is altered.

Deletion mapping of the mouse ornithine decarboxylase-related locus Odc-rs8 within Igh-V.

The Odc-rs8 locus belongs to a family of mouse DNA sequences related to the gene encoding ornithine decarboxylase (ODC). Odc-rs8 was mapped by recombinant inbred (RI) strain analysis to the region of Chromosome (Chr) 12 occupied by the variable region genes of the immunoglobulin heavy chain (Igh) complex. In the present study, alleles at Odc-rs8 were shown to cosegregate with those for Igh variable region (Igh-V or VH) genes among 37 inbred mouse strains that had been characterized previously for their haplotypes at Igh. For a more precise definition of the location of Odc-rs8 relative to Igh-V, DNAs from 17 Abelson murine leukemia virus (A-MuLV)-transformed pre-B cell lines cultured from mice heterozygous at Igh and Odc-rs8 were analyzed for the presence of DNA restriction fragments (RFs) derived from each parental Odc-rs8 allele. These cell lines, each of which has rearranged one or both Igh genes, previously were employed in mapping members of nine VH gene families by deletion analysis (Brodeur et al. 1988). Comparing the deletion profiles of the cell lines for Odc-rs8 with those for the VH gene families has located Odc-rs8b within the VHJ558/VH3609 gene cluster and Odc-rs8c either within or upstream of the 5'-most 9% of VHJ558, identifying Odc-rs8 as a potentially useful marker for the 5' end of the Igh complex.

Structure, map position, and evolution of two newly diverged mouse Ig VH gene families.

We have characterized two novel mouse VH gene families, VH3609N and VHSM7. These VH families have recently diverged from previously defined VH families. The VH3609N family, which may contain only one member in most inbred strains of mice, shares sequence similarity with the VHJ606 family and is located to the 3' side of VHJ606. VHSM7, with at least three members, is related to the VHJ558 family but maps 3' of VHJ558. These findings suggest that physical displacement of VH sequences may facilitate their subsequent divergence. During the early stages of VH gene family evolution that are exemplified by these new families, amino acid replacements have been selected against in frame-work regions and selected for in complementarity-determining regions. This pattern of nucleotide substitution appears to reflect evolutionary pressures to maintain germ-line VH diversity and, possibly, to select for new antibody specificities, as well as to select against mutations resulting in aberrant Ig. The classification of VH sequences with borderline similarity to previously defined VH families is discussed.

Utilization of V kappa families and V kappa exons. Implications for the available B cell repertoire.

A molecular cloning approach was used to determine the relative utilization of 2 individual V kappa 21 genes, 13 V kappa gene families, and the 4 functional J kappa gene segments among splenic B cells of nonimmunized BALB/c mice. Based on the observed frequency of individual V kappa gene expression, we estimate that the mouse genome encodes 150 to 180 functional V kappa genes, and we suggest that most functional V kappa exons are expressed at comparable frequencies in the preimmune antibody repertoire. In contrast, clear differences in J kappa segment utilization were observed, J kappa 4 being consistently underrepresented with respect to the other J kappa segments.

Community values in Vermont health planning.

KIE: This is one of a set of six short articles, grouped under the umbrella title "Grassroots bioethics revisited: health care priorities and community values," with a very brief introduction by Bruce Jennings. The articles focus on the involvement of community health decisions projects with public policy issues of access to health care, allocation of resources, setting health care priorities, cost containment, and rationing.^ieng