Manipulating the extracellular matrix and its role in brain and spinal cord plasticity and repair.

Brain and spinal cord injury can result in permanent cognitive, motor, sensory and autonomic deficits. The central nervous system (CNS) has a poor intrinsic capacity for regeneration, although some functional recovery does occur. This is mainly in the form of sprouting, dendritic remodelling and changes in neuronal coding, firing and synaptic properties; elements collectively known as plasticity. An important approach to repair the injured CNS is therefore to harness, promote and refine plasticity. In the adult, this is partly limited by the extracellular matrix (ECM). While the ECM typically provides a supportive framework to CNS neurones, its role is not only structural; the ECM is homeostatic, actively regulatory and of great signalling importance, both directly via receptor or coreceptor-mediated action and via spatially and temporally relevant localization of other signalling molecules. In an injury or disease state, the ECM represents a key environment to support a healing and/or regenerative response. However, there are aspects of its composition which prove suboptimal for recovery: some molecules present in the ECM restrict plasticity and limit repair. An important therapeutic concept is therefore to render the ECM environment more permissive by manipulating key components, such as inhibitory chondroitin sulphate proteoglycans. In this review we discuss the major components of the ECM and the role they play during development and following brain or spinal cord injury and we consider a number of experimental strategies which involve manipulations of the ECM, with the aim of promoting functional recovery to the injured brain and spinal cord.

Characterization of an immune-evading doxycycline-inducible lentiviral vector for gene therapy in the spinal cord.

Gene therapy is a powerful approach to promote spinal cord regeneration. For a clinical application it is important to restrict therapeutic gene expression to the appropriate time window to limit unwanted side effects. The doxycycline (dox)-inducible system is a widely used regulatable gene expression platform, however, this system depends on a bacterial-derived immunogenic transactivator. The foreign origin of this transactivator prevents reliable regulation of therapeutic gene expression and currently limits clinical translation. The glycine-alanine repeat (GAR) of Epstein-Barr virus nuclear antigen-1 protein inhibits its presentation to cytotoxic T cells, allowing virus-infected cells to evade the host immune system. We developed a chimeric transactivator (GARrtTA) and show that GARrtTA has an immune-evading advantage over "classical" rtTA in vivo. Direct comparison of lentiviral vectors expressing rtTA and GARrtTA in the rat spinal cord shows that the GARrtTA system is inducible for 6 doxycycline-cycles over a 47 week period, whereas with the rtTA-based system luciferase reporter expression declines during the 3rd cycle and is no longer re-inducible, indicating that GARrtTA provides an immune-advantage over rtTA. Immunohistochemistry revealed that GARrtTA expressing cells in the spinal cord appear healthier and survive better than rtTA expressing cells. Characterization of the immune response shows that expression of GARrtTA, in contrast to rtTA, does not recruit cytotoxic T-cells to the transduced spinal cord. This study demonstrates that fusion of the GAR domain to rtTA results in a functional doxycycline-inducible transactivator with a clear immune-advantage over the classical rtTA in vivo.

Antibody and cell-mediated immune responses and survival between Holstein and Norwegian Red × Holstein Canadian calves.

As an extension of a former study, the objectives of this study were to evaluate purebred Holstein (HO; n=140) and crossbred Norwegian Red × Holstein (NRFX; n=142) calves for antibody (AMIR) and cell-mediated immune responses (CMIR) as well as survival. Blood was collected on d 0, 14, and 21, and calves were immunized on d 0 and 14 with type 1 (Candida albicans) and type 2 (hen egg white lysozyme) antigens, which have been shown to induce CMIR and AMIR, respectively. Day 21 background skin-fold measurements of either side of the tail-fold were taken and intradermal injections of test (type 1 antigen) and control (phosphate saline buffer) were administered. Day 23 final skin-fold measurements were taken to assess delayed type hypersensitivity as an indicator of CMIR. Survival data were obtained from CanWest Dairy Herd Improvement. Statistical Analysis System general linear models were used to analyze all immune response and survival data and to determine statistical significance between breeds. Results showed that NRFX had greater primary IgM, IgG, IgG1, and secondary IgG1 antibody response, as well as greater primary IgG1:IgG2 ratio to the type 2 antigen compared with HO. The NRFX also had greater primary IgG1 and IgG2, and secondary IgG2 antibody response as well as greater primary IgG1:IgG2 ratio to the type 1 antigen. The NRFX calves had a tendency toward greater survival from age at immune response testing to calving. No difference was observed between breeds for other secondary antibody response traits or delayed type hypersensitivity. Results indicate NRFX have greater AMIR and therefore may have enhanced defense against extracellular pathogens. This may contribute to increased survival compared with HO. Both breeds, however, likely have similar defense against intracellular pathogens, because no differences in CMIR were observed. In general, these results may suggest that crossbreeding could improve resistance to certain diseases in dairy calves, resulting in decreased input costs to producers for crossbred calves compared with purebred calves. However, more research with larger sample sizes and different breeds should be conducted to confirm these results and obtain a complete picture of the benefits of crossbreeding on immune response traits in calves.

Immune responses of Holstein and Norwegian Red x Holstein calves on Canadian dairy farms.

The objective of this study was to compare the immune response of Holstein and Norwegian Red x Holstein calves on 13 commercial Canadian dairy farms. Data were collected on 135 calves, 68 Holstein and 67 Norwegian Red x Holstein calves aged between 2 and 6 mo. The calves were immunized with hen egg white lysozyme to induce antibody-mediated immune response. Candida albicans was used as an in vivo indicator of cell-mediated immune response, with delayed-type hypersensitivity used as the indicator. Antibody response to hen egg white lysozyme (IgG, IgG1, and IgG2) was measured by ELISA. Calves of both breed groups produced a significant primary and secondary antibody-mediated immune response, as well as a delayed-type hypersensitivity reaction. The Norwegian Red x Holstein produced a greater primary IgG antibody-mediated immune response (d 14, and d 14 minus d 0) when compared with the Holstein. No differences were observed between the breeds for secondary response or antihen egg white lysozyme isotype (IgG1 or IgG2) production or the ratio of IgG1:IgG2. There was no effect of breed on delayed-type hypersensitivity. Nonetheless, high and low immune responders could be identified in both breed groups, but with no difference in the proportion of high and low responders observed for either antibody-mediated immune response or cell-mediated immune response between breed groups.

The impact of alternative practices on the cost and quality of mammographic screening in the United States.

The decentralized structure of health care in the Unites States hinders population-based analysis of breast cancer screening. Our objectives are to model mammography in the United States as a whole, to identify the variables that most profoundly affect cost and efficacy, and to develop a strategy to improve mammography screening from a population perspective. A spreadsheet model was used to represent the variables of mammography screening in the United States. The population-based national screening program in Sweden provides a framework for comparison. The outcome measures are the aggregate cost and the number of cancers detected by mammography. We used deterministic sensitivity analysis to calculate the impact of variation in practice. Aggregate costs of screening in the United States are in the range of $3-$5 billion dollars. The percentage of women screened, cost per mammogram, cancer to biopsy ratio, recall rate, and cost of recall have the most profound effect on the quality and cost of a national screening program. Variance of these high-impact variables, based on the U.S. population, modifies the aggregate cost of screening by over $2 billion. As mammography screening in the United States increases to include all women over age 40, high-impact variables should be optimized to decrease costs and improve breast cancer detection. Our model establishes which parameters are most important.

Controlled breeding of dairy cows with cloprostenol.

The percentage of dairy cows that were mated and became pregnant during a 42 day breeding period was not significantly different when animals were routinely observed for estrus and mated when detected (71%, n = 56), inseminated at estrus following a single injection of cloprostenol (72%, n = 29), or inseminated at a fixed time after two cloprostenol treatments 11 days apart (69%, n = 28). However, 11 cows in the control group were not detected and mated during the breeding period and inclusion of these animals reduced the actual pregnancy rate to 60%. Results indicated that a controlled breeding program could have practical application in dairy herds but should be used with caution. Practitioners must evaluate management programs and decide, in consultation with the herdsman, if the introduction of controlled breeding technology might be advantageous.

Using multidimensional mutual information to prioritize mammographic features for breast cancer diagnosis.

The goal of this study was to demonstrate that information theory could be used to prioritize mammographic features to efficiently stratify the risk of breast cancer. We compared two approaches, Single-dimensional Mutual Information (SMI), which ranks features based on mutual information of features with outcomes without considering dependency of other features, and Multidimensional Mutual Information (MMI), which ranks features by considering dependency. To evaluate these approaches, we calculated area under the ROC curve for Bayesian networks trained and tested on features ranked by each approach. We found that both approaches were able to stratify mammograms by risk, but MMI required fewer features (ten vs. thirteen). MMI-based rankings may have greater clinical utility; a smaller set of features allows radiologists to focus on those findings with the highest yield and in the future may help improve mammography workflow.

Adaptive immune response, survival, and somatic cell score between postpartum Holstein and Norwegian Red × Holstein first-calf heifers.

The objectives of this study were to evaluate antibody (AMIR) and cell-mediated immune responses (CMIR), survival, and somatic cell score (SCS) between purebred Holstein (HO) and crossbred Norwegian Red × Holstein (NRHO) first-calf heifers postpartum. Additionally, immune response traits observed as calves in a previous study were correlated with their immune response traits as first-calf heifers. Heifers, previously immunized as calves, were bled and reimmunized 6 to 9 d postcalving with known type 1 and type 2 antigens and human serum albumin (HSA). Seven days later, heifers were rebled, and background skinfold measurements of the tail fold were taken. Intradermal injections of PBS and type 1 antigen were administered on either side of the tail fold. On d 9 final skinfold measurements were taken and used to assess delayed-type hypersensitivity (DTH) as an indicator of CMIR. Blood samples were also collected for a final time on d 14 from heifers that received the antigen HSA. Serum was obtained from blood collected on d 0, 7, and 14 and analyzed by ELISA to assess AMIR. Data on survival and somatic cell count, which was converted to SCS, were obtained from CanWest Dairy Herd Improvement (DHI). All SCS, survival, and immune response data were analyzed using general linear models to determine significance between HO and NRHO first-calf heifers. To determine residual correlations between immune response traits observed in calves to their responses as first-calf heifers, residuals were obtained from models, and correlations between traits were determined using PROC CORR in SAS. Results showed NRHO had a greater primary IgG antibody response to HSA and greater tertiary IgG antibody response to the type 2 antigen compared with HO. Crossbreds (NRHO)also had significantly greater DTH response (P < 0.05) and, in general, greater survival from calving to 100 d in milk (dim), 100 to 305 dim, calving to 305 dim, and age at immune response testing as calf to 305 dim. No difference was observed between breeds for SCS. Results also showed most correlations between calf and first-calf heifer immune response traits were found to be positive and significant (P < 0.05). In conclusion, NRHO heifers have greater survival, which likely relates at least in part to increases in aspects of both AMIR and CMIR and could indicate that crossbred heifers have enhanced disease resistance.

Integrating machine learning and physician knowledge to improve the accuracy of breast biopsy.

In this work we show that combining physician rules and machine learned rules may improve the performance of a classifier that predicts whether a breast cancer is missed on percutaneous, image-guided breast core needle biopsy (subsequently referred to as "breast core biopsy"). Specifically, we show how advice in the form of logical rules, derived by a sub-specialty, i.e. fellowship trained breast radiologists (subsequently referred to as "our physicians") can guide the search in an inductive logic programming system, and improve the performance of a learned classifier. Our dataset of 890 consecutive benign breast core biopsy results along with corresponding mammographic findings contains 94 cases that were deemed non-definitive by a multidisciplinary panel of physicians, from which 15 were upgraded to malignant disease at surgery. Our goal is to predict upgrade prospectively and avoid surgery in women who do not have breast cancer. Our results, some of which trended toward significance, show evidence that inductive logic programming may produce better results for this task than traditional propositional algorithms with default parameters. Moreover, we show that adding knowledge from our physicians into the learning process may improve the performance of the learned classifier trained only on data.

Impact of somatotropin and other biochemical products on sire summaries and cow indexes.

This paper outlines the potential impact of bovine somatotropin on dairy cattle improvement programs and pinpoints research needs. Recording of manufacturer, dosage, and date of start and finish of somatotropin administration is recommended in order to allow analysis of data for cow and sire ranking. Alternatives, such as restriction of somatotropin administration to certain lactations or parts of the cow's lactation are discussed. Cooperator herds or nucleus breeding schemes as alternatives to the random sampling of AI bulls may become more practical if somatotropin is widely used in the future.

Evaluation of dairy bulls in Ontario for calving ease of offspring.

The first sire evaluations for calving ease for bulls used in Ontario were published in May, 1981. Evaluations used calving records collected by Ontario Dairy Herd Improvement Association from all supervised herds from May, 1980, to April, 1981. A total of 34,240 records including herd, breed, sire, and cow identification, date of calving, and information about cow size, parity, sex of calf, mortality, and dystocia score were collected. After editing, 28,947 records were available from 1,178 Holstein bulls. Dystocia scores were 1) unobserved or unassisted, 2) easy pull, 3) hard pull, and 4) surgery. Stillbirths represented 5.5% of births coded 1 and 2, 25.1% of births coded hard pull, and 50.7% of surgical births. Analysis of variance showed that cow size, sex of calf, parity, and season (May to September and October to April) affected dystocia scores. Variance components were estimated prior to evaluation by Henderson's new method and resulted in a heritability of .08. Sire evaluation was by best linear unbiased prediction and included the relationship matrix. The prediction model included herd-year-season, dam size-parity-sex, and sire effects. Ninety-one sires had evaluations with a Repeatability of at least 55% and records in at least 20 herd-year-seasons.

Merrill C. Sosman Lecture. Surviving managed care.

Managed care has arrived, especially on the West Coast. This tsunami is moving eastward at a rapid rate. Perhaps the experience with killer bees will be repeated with managed care, with decreased virulence as this wave moves across the country. Institutions would be wise to prepare for these changes with improved efficiency and cost-effectiveness. Radiologists are particularly at risk and need to aggressively adapt to managed care by becoming informed, developing a clear strategy for coping, and then executing their plan. Evolution will demonstrate once again the survival of the fittest.

The effect of repeated cycles of selection on genetic variance, heritability, and response.

The genetic variance of a quantitative trait decreases under directional selection due to generation of linkage disequilibrium. After a few cycles of selection on individual phenotype, a limit is reached where there is no further reduction in the genetic variance. Bulmer's model is extended to an animal breeding situation where selection is on information on relatives rather than on the individual's own performance. Algebraic expressions are derived to predict the decrease in genetic variance and associated reductions in heritability and response in the limit. Consequences of the results are discussed in the context of breeding strategies.

Joint sire and cow evaluation for conformation traits using an individual animal model.

A joint sire and cow evaluation for selected type traits has been carried out for the Canadian Holstein population using an individual animal model accounting for all known relationships. Only first lactation, first classification linear records were utilized. Linear scores for final class/final score (combined), feet and legs, mammary system, and stature were analyzed. The model of analysis included animals' additive genetic merit as random and herd-round-classifier subclasses as fixed effects. Calving age and stage of lactation at classification were fitted as linear and quadratic covariables. There were 282,030 cows with records, 198,871 dams without records, and 8481 sires (i.e., 489,382 animals in total). Combined with 33,968 herd-round-classifier effects in 9654 herds and four regression coefficients, a system of 523,354 equations required simultaneous solution. Solutions were obtained iteratively for one trait at a time. The computing strategy utilized is described, and a detailed worked example is given. Correlations between sire proofs and the current Holstein sire proofs were .89 to .96 for sires with at least 20 daughters in five or more herds. Correlations between cow indexes and phenotypic scores ranged from .53 to .76. The coefficient of determination in a multiple regression of daughter's index on dam's index and sire's and maternal grandsire's proof was 78 to 92% but only 59 to 83% when dam's index was replaced by dam's phenotypic record.

A Bayesian network for mammography.

The interpretation of a mammogram and decisions based on it involve reasoning and management of uncertainty. The wide variation of training and practice among radiologists results in significant variability in screening performance with attendant cost and efficacy consequences. We have created a Bayesian belief network to integrate the findings on a mammogram, based on the standardized lexicon developed for mammography, the Breast Imaging Reporting And Data System (BI-RADS). Our goal in creating this network is to explore the probabilistic underpinnings of this lexicon as well as standardize mammographic decision-making to the level of expert knowledge.

Selection of sires to reduce sampling variance in the estimates of heritability by half-sib correlation.

Standard methods to estimate heritability by half-sib correlation are biased if selection has operated in the parental generation. In this paper a simple method to correct for selection of animals used as sires is described. By selection of both the top and the bottom ranking sires, the sampling variances of the corrected estimates of heritability are substantially reduced. Algebraic expressions to predict the sampling variance of the estimates of heritability using selected sires are derived. Theoretical predictions were checked by Monte-Carlo simulation. The results may have application in the design of experiments to estimate heritabilities.

Nonadditive genetic effects and inbreeding depression for somatic cell counts of Holstein cattle.

A total of 65,491 lactation means of log2-transformed SCC measures were analyzed from first lactation Holstein cows in Ontario. Effects of inbreeding on SCC were estimated by a nonadditive sire and dam model that included additive, dominance, and additive by additive genetic effects and regression of lactation somatic cell score on inbreeding coefficients of the cows. Variance components were estimated using the tildehat approximation to REML. Solutions were by iteration on data. Estimates of heritability for lactation somatic cell score in the narrow sense were .165 and in the broad sense were .203. The additive by additive component (2.5% of the total phenotypic variance) was almost twice as large as the dominance component (1.3%). The regression coefficient of lactation somatic cell score per 1% increase of inbreeding was .012. The average increase of the population mean of lactation somatic cell score caused by a 10% increase of inbreeding coefficient was estimated to be 10.5% of the original phenotypic standard deviation of 1.153. The inbreeding depression was thus relatively low, but, on average, inbred animals tended to have higher lactation somatic cell score. This study provides preliminary evidence that inbreeding is related to disease prevalence in large purebred dairy populations.

Production traits of Holstein cattle: estimation of nonadditive genetic variance components and inbreeding depression.

Additive, dominance, and additive by additive components of genetic variance and inbreeding depression were estimated for production traits from a group of daughters of young sires from the Canadian Holstein population. First lactations of 92,838 cows were analyzed. Three sire and dam models (additive, additive plus dominance, additive plus dominance plus additive by additive genetic effects), all including regression of the trait on inbreeding coefficient of the cow, were used to estimate the effect of inbreeding on production traits. For all production traits, heritability in the narrow sense was overestimated with the simplest model, in which only the additive effect was fitted. Estimates of dominance variance were low for all traits, .9 to 3%. Additive by additive components were low for milk, 2.8%, and fat yield, 2.8%, but higher for protein yield, 6.8%, and for fat, 9%, and protein percentages, 8.9%. Estimates of inbreeding depression for the five traits were similar across all models (-25, -.9, and -.8 kg; .05% and .05% per 1% increase in inbreeding for milk, fat, and protein production and fat and protein percentages, respectively). More accurate estimates of additive effects might be obtained with the inclusion of nonadditive effects for genetic evaluation. If the estimation of inbreeding depression is the only objective, simple models and small random samples of the population may be adequate.

Relationships between conformation and calving interval in Holstein cows.

Type information collected by the Holstein Association of Canada from 1976 to 1983 was matched with calving interval records from the Record of Performance program of Agriculture Canada. Type traits considered were final class, major scorecard breakdown traits (general appearance, dairy character, capacity, rump, feet and legs, mammary system, fore udder, rear udder), and eight descriptive traits (stature, size, style, dairyness, chest floor, loin strength, thurl width, pin setting). The edited data consisted of 22,791 records on first calf heifers by 2548 sires in 9272 herd-round of classification groups. Sire evaluations for both type and calving interval were available for 3312 sires. Heritability of calving interval was estimated to be .04. Heritability estimates of type traits ranged from .06 for style to .33 for size. Phenotypic correlations between the type traits and calving interval were essentially zero. The highest favorable genetic correlations with calving interval were for chest floor (-.42), rear udder (-.37), capacity (-.34), and highest antagonistic correlations were for dairyness (.43) and dairy character (.38). Direct selection for improved calving interval was estimated to be more efficient than indirect selection on any of the type traits considered.