Palladin isoforms 3 and 4 regulate cancer-associated fibroblast pro-tumor functions in pancreatic ductal adenocarcinoma

Pancreatic Ductal Adenocarcinoma (PDAC) has a five-year survival under 10%. Treatment is compromised due to a fibrotic-like stromal remodeling process, known as desmoplasia, which limits therapeutic perfusion, supports tumor progression, and establishes an immunosuppressive microenvironment. These processes are driven by cancer-associated fibroblasts (CAFs), functionally activated through transforming growth factor beta1 (TGFβ1). CAFs produce a topographically aligned extracellular matrix (ECM) that correlates with reduced overall survival. Paradoxically, ablation of CAF populations results in a more aggressive disease, suggesting CAFs can also restrain PDAC progression. Thus, unraveling the mechanism(s) underlying CAF functions could lead to therapies that reinstate the tumor-suppressive features of the pancreatic stroma. CAF activation involves the f-actin organizing protein palladin. CAFs express two palladin isoforms (iso3 and iso4) which are up-regulated in response to TGFβ1. However, the roles of iso3 and iso4 in CAF functions remain elusive. Using a CAF-derived ECM model, we uncovered that iso3/iso4 are required to sustain TGFβ1-dependent CAF activation, secrete immunosuppressive cytokines, and produce a pro-tumoral ECM. Findings demonstrate a novel role for CAF palladin and suggest that iso3/iso4 regulate both redundant and specific tumor-supportive desmoplastic functions. This study highlights the therapeutic potential of targeting CAFs to restore fibroblastic anti-tumor activity in the pancreatic microenvironment.

The effect of motorcycle helmet fit on estimating head impact kinematics from residual liner crush

Proper helmet fit is important for optimizing head protection during an impact, yet many motorcyclists wear helmets that do not properly fit their heads. The goals of this study are i) to quantify how a mismatch in headform size and motorcycle helmet size affects headform peak acceleration and head injury criteria (HIC), and ii) to determine if peak acceleration, HIC, and impact speed can be estimated from the foam liner's maximum residual crush depth or residual crush volume. Shorty-style helmets (4 sizes of a single model) were tested on instrumented headforms (4 sizes) during linear impacts between 2.0 and 10.5m/s to the forehead region. Helmets were CT scanned to quantify residual crush depth and volume. Separate linear regression models were used to quantify how the response variables (peak acceleration (g), HIC, and impact speed (m/s)) were related to the predictor variables (maximum crush depth (mm), crush volume (cm³), and the difference in circumference between the helmet and headform (cm)). Overall, we found that increasingly oversized helmets reduced peak headform acceleration and HIC for a given impact speed for maximum residual crush depths less than 7.9mm and residual crush volume less than 40cm³. Below these levels of residual crush, we found that peak headform acceleration, HIC, and impact speed can be estimated from a helmet's residual crush. Above these crush thresholds, large variations in headform kinematics are present, possibly related to densification of the foam liner during the impact.

The impact response of traditional and BMX-style bicycle helmets at different impact severities

Bicycle helmets reduce the frequency and severity of severe to fatal head and brain injuries in bicycle crashes. Our goal here was to measure the impact attenuation performance of common bicycle helmets over a range of impact speeds. We performed 127 drop tests using 13 different bicycle helmet models (6 traditional style helmets and 7 BMX-style helmets) at impact speeds ranging from 1 to 10m/s onto a flat anvil. Helmets were struck on their left front and/or right front areas, a common impact location that was at or just below the test line of most bicycle helmet standards. All but one of the 10 certified helmet models remained below the 300g level at an impact speed of 6m/s, whereas none of the 3 uncertified helmets met this criterion. We found that the helmets with expanded polystyrene liners performed similarly and universally well. The single certified helmet with a polyurethane liner performed below the level expected by the Consumer Product Safety Commission (CPSC) standard at our impact location and the helmet structure failed during one of two supplemental tests of this helmet above the test line. Overall, we found that increased liner thickness generally reduced peak headform acceleration, particularly at higher impact speeds.

The impact response of motorcycle helmets at different impact severities

Helmets reduce the frequency and severity of head and brain injuries over a range of impact severities broader than those covered by the impact attenuation standards. Our goal was to document the impact attenuation performance of common helmet types over a wide range of impact speeds. Sixty-five drop tests were performed against the side of 10 different helmets onto a flat anvil at impact speeds of 0.9-10.1 m/s (energy=2-260J; equivalent drop heights of 0.04-5.2 m). Three non-approved beanie helmets performed poorly, with the worst helmet reaching a peak headform acceleration of 852g at 29J. Three full-face and one open-face helmet responded similarly from about 100g at 30J to between 292g and 344g at 256-260J. Three shorty style helmets responded like the full-face helmets up to 150J, above which varying degrees of foam densification appeared to occur. Impact restitution values varied from 0.19 to 0.46. A three-parameter model successfully captured the plateau and densification responses exhibited by the various helmets (R(2)=0.95-0.99). Helmet responses varied with foam thickness, foam material and possibly shell material, with the largest response differences consistent with either the presence/absence of a foam liner or the densification of the foam liner.

Utilized friction when entering and exiting a dry and wet bathtub

Bathtubs and showers are a common source of unintentional slips and falls. The goal of this study was to quantify the friction used by barefoot subjects entering and exiting a typical bathtub/shower enclosure under dry and wet conditions. Sixty subjects (30F, 30M) from three age groups (20-30 years, 40-50 years, 60-70 years) entered and exited a slip-resistant bathtub using six movement patterns (three entering and three exiting the tub) simulating actual use. Force plates installed in the tub floor and the slip-resistant deck outside the tub measured ground reaction forces, from which utilized friction and double support times were calculated. Overall, utilized friction varied from 0.102 to 0.442 (0.235+/-0.057) and was 0.058+/-0.040 lower in wet than dry conditions across all movement patterns (p<0.0001). During tub exiting movements, older subjects used less friction than young subjects (p<0.006). Utilized friction did not vary between genders (p>0.14). Double support times were longer in older subjects than in both young and middle-aged subjects for all movement patterns (p<0.0009) and longer under wet than dry conditions for all entry movements (p<0.0001). These data suggest that subjects regard the wet condition as more hazardous than the dry condition and adapt their utilized friction accordingly. These data also show that older subjects are more cautious than young subjects when confronted with the dual tasks of stepping over the tub's apron and transitioning to a surface perceived to be more slippery.

An application of multivariate ranks to assess effects from combining factors: metal exposures and semen analysis outcomes

In studies of environmental effects on human health outcomes, it is often difficult to assess the effects of a group of exposure variables when the individual exposures do not appear to have statistically significant effects. To address this situation, we propose a method of U-scores applied to subsets of multivariate data. We illustrate the usefulness of this approach by applying it to data collected as part of a study on the effects of metal exposure on human semen parameters. In this analysis, profiles (pairs) of metals containing copper and/or manganese were negatively correlated with total motile sperm and profiles containing copper were negatively correlated with sperm morphology; profiles containing selenium and chromium were positively correlated with total motile sperm.

Three-dimensional finite element modeling of ligaments: technical aspects

The objective of this paper is to describe strategies for addressing technical aspects of the computational modeling of ligaments with the finite element (FE) method. Strategies for FE modeling of ligament mechanics are described, differentiating between whole-joint models and models of individual ligaments. Common approaches to obtain three-dimensional ligament geometry are reviewed, with an emphasis on techniques that rely on volumetric medical image data. Considerations for the three-dimensional constitutive modeling of ligaments are reviewed in the context of ligament composition and structure. A novel approach to apply in situ strain to FE models of ligaments is described, and test problems are presented that demonstrate the efficacy of the approach. Approaches for the verification and validation of ligament FE models are outlined. The paper concludes with a discussion of future research directions.

Subject-specific finite element analysis of the human medial collateral ligament during valgus knee loading

The objectives of this study were (1) to develop subject-specific experimental and finite element (FE) techniques to study the three-dimensional stress-strain behavior of ligaments, with application to the human medial collateral ligament (MCL), and (2) to determine the importance of subject-specific material properties and initial (in situ) strain distribution for prediction of the strain distribution in the MCL under valgus loading. Eight male knees were subjected to varus-valgus loading at flexion angles of 0 degrees, 30 degrees, and 60 degrees. Three-dimensional joint kinematics and MCL strains were recorded during kinematic testing. Following testing, the MCL of each knee was removed to allow measurement of the in situ strain distribution and to perform material testing. A FE model of the femur-MCL-tibia complex was constructed for each knee to simulate valgus loading at each flexion angle, using subject-specific bone and ligament geometry, material properties, and joint kinematics. A transversely isotropic hyperelastic material model was used to represent the MCL. The MCL in situ strain distribution at full extension was used to apply in situ strain to each MCL FE model. FE predicted MCL strains during valgus loading were compared to experimental measurements using regression analysis. The subject-specific FE predictions of strain correlated reasonably well with experimentally measured MCL strains (R(2)=0.83, 0.72, and 0.66 at 0 degrees, 30 degrees, and 60 degrees, respectively). Despite large inter-subject variation in MCL material properties, MCL strain distributions predicted by individual FE models that used average MCL material properties were strongly correlated with subject-specific FE strain predictions (R(2)=0.99 at all flexion angles). However, predictions by FE models that used average in situ strain distributions yielded relatively poor correlations with subject-specific FE predictions (R(2)=0.44, 0.35, and 0.33 at flexion angles of 0 degrees, 30 degrees, and 60 degrees, respectively). The strain distribution within the MCL was nonuniform and changed with flexion angle. The highest MCL strains occurred at full extension in the posterior region of the MCL proximal to the joint line during valgus loading, suggesting this region may be most vulnerable to injury under these loading conditions. This work demonstrates that subject-specific FE models can predict the complex, nonuniform strain fields that occur in ligaments due to external loading of the joint.

Control of cellulose synthase complex localization in developing xylem

Cellulose synthesis in the developing xylem vessels of Arabidopsis requires three members of the cellulose synthase (CesA) gene family. In young vessels, these three proteins localize within the cell, whereas in older vessels, all three CesA proteins colocalize with bands of cortical microtubules that mark the sites of secondary cell wall deposition. In the absence of one subunit, however, the remaining two subunits are retained in the cell, demonstrating that all three CesA proteins are required to assemble a functional complex. CesA proteins with altered catalytic activity localize normally, suggesting that cellulose synthase activity is not required for this localization. Cortical microtubule arrays are required continually to maintain normal CesA protein localization. By contrast, actin microfilaments do not colocalize with the CesA proteins and are unlikely to play a direct role in their localization. Green fluorescent protein-tagged CesA reveals a novel process in which the structure and/or local environment of the cellulose synthase complex is altered rapidly.

A 75-kDa plant protein isolated by tubulin-affinity chromatography is a peroxisomal matrix enzyme

The function of microtubules in plant cells relies on their interactions with various, largely unidentified, proteins. A 75-kDa polypeptide (p75) was isolated previously by tubulin affinity chromatography of tobacco BY-2 proteins and is further characterized here. We have obtained two peptide sequences of 13 and 8 amino acid residues from the p75, which have 77% and 87% similarity to two putative dTDP-glucose 4,6-dehydratase proteins of 74.9 and 75.3 kDa in Arabidopsis. The proteins contain a peroxisomal matrix targeting signal SKL or AKL near their carboxyl terminus, an epimerase-dehydratase motif, and a region of 321 amino acid residues sharing 41% similarity with a dTDP-glucose 4,6-dehydratase from Aneurinibacillus thermoaerophilus. A monoclonal antibody 4B9 against the tobacco p75 reacted with a 75-kDa polypeptide on immunoblots of tobacco BY-2 and Arabidopsis protein extracts, and in immunofluorescence microscopy it revealed small organelle-like structures in tobacco BY-2 and Arabidopsis root-tip cells. Double labelling with an antibody against the peroxisomal marker enzyme, catalase, showed that the organelles are indeed peroxisomes. The peroxisomes were in closer association with actin filaments than microtubules. This observation supports recent findings that plant peroxisomes move on actin filaments. We propose that the peroxisomal dTDP-glucose 4,6-dehydratases may be involved in plant defence responses to oxidative stress.Key words: actin, antibodies, microtubules.

Ligament material behavior is nonlinear, viscoelastic and rate-independent under shear loading

The material behavior of ligament is determined by its constituents, their organization and their interaction with each other. To elucidate the origins of the multiaxial material behavior of ligaments, we investigated ligament response to shear loading under both quasi-static and rate-dependent loading conditions. Stress relaxation tests demonstrated that the tissue was highly viscoelastic in shear, with peak loads dropping over 40% during 30 min of stress relaxation. The stress relaxation response was unaffected by three decades of change in shear strain rate (1.3, 13 and 130%/s). A novel parameter estimation technique was developed to determine material coefficients that best described the experimental response of each test specimen to shear. The experimentally measured clamp displacements and reaction forces from the simple shear tests were used with a nonlinear optimization strategy based around function evaluations from a finite element program. A transversely isotropic material with an exponential matrix strain energy provided an excellent fit to experimental load-displacement curves. The shear modulus of human MCL showed a significant increase with increasing shear strain (p<0.001), reaching a maximum of 1.72+/-0.4871 MPa. The results obtained from this study suggest that viscoelasticity in shear does not likely result from fluid flow. Gradual loading of transversely oriented microstructural features such as intermolecular collagen crosslinks or collagen-proteoglycan crosslinking may be responsible for the stiffening response under shear loading.

Computational modeling of ligament mechanics

This article provides a critical review of past and current techniques for the computational modeling of ligaments and tendons. A brief overview of relevant concepts from the fields of continuum mechanics and finite element analysis is provided. The structure and function of ligaments and tendons are reviewed in detail, with emphasis on the relationship of microstructural tissue features to the continuum mechanical hehavior. Experimental techniques for the material characterization of biological soft tissues are discussed. Past and current efforts related to the constitutive modeling of ligaments and tendons are classified by the particular technique and dimensionality. Applications of one-dimensional and three-dimensional constitutive models in the representation of the mechanical behavior of joints are presented. Future research directions are identified.

Strain in the human medial collateral ligament during valgus loading of the knee

The medial collateral ligament is one of the most frequently injured ligaments in the knee. Although the medial collateral ligament is known to provide a primary restraint to valgus and external rotations, details regarding its precise mechanical function are unknown. In this study, strain in the medial collateral ligament of eight knees from male cadavers was measured during valgus loading. A material testing machine was used to apply 10 cycles of varus and valgus rotation to limits of +/- 10.0 N-m at flexion angles of 0 degrees, 30 degrees, 60 degrees, and 90 degrees. A three-dimensional motion analysis system measured local tissue strain on the medial collateral ligament surface within 12 regions encompassing nearly the entire medial collateral ligament surface. Results indicated that strain is significantly different in different regions over the surface of the medial collateral ligament and that this distribution of strain changes with flexion angle and with the application of a valgus torque. Strain in the posterior and central portions of the medial collateral ligament generally decreased with increasing flexion angle, whereas strain in the anterior fibers remained relatively constant with changes in flexion angle. The highest strains in the medial collateral ligament were found at full extension on the posterior side of the medial collateral ligament near the femoral insertion. These data support clinical findings that suggest the femoral insertion is the most common location for medial collateral ligament injuries.

The effect of subclinical Mycobacterium paratuberculosis infection on milk production in Michigan dairy cows

The objective of this study was to determine the effect of subclinical Mycobacterium paratuberculosis infection on mature equivalent milk, protein, and fat production in a sample of Michigan dairy herds with a history of cows positive for M. paratuberculosis diagnosed by fecal culture. A prospective two-group cohort study was conducted. Participating herds were tested, and productivity and reproduction records were monitored for 18 mo. All cows aged 24 mo and greater were tested for M. paratuberculosis infection using the ELISA and radiometric fecal culture (RFC) techniques. Using both tests in parallel, the overall sample apparent prevalence for M. paratuberculosis infection was 41.8%. Adjusting for diagnostic sensitivity and specificity resulted in a calculated sample true prevalence of 59.9%. Subclinical paratuberculosis test-positive status had no statistically significant effect on mature equivalent milk, fat, or protein production. The results of this study concur with the findings of other studies, reporting that the magnitude and direction of the association between subclinical paratuberculosis infection and milk production depends upon the parity of the animal, stage of disease, and the stage in lactation being monitored. Assessment of the impact of subclinical paratuberculosis on milk production must consider the average parity of the sample population. In herds that have an average parity of 2 or less, subclinical paratuberculosis infection may have little impact on milk production.

A 90-kD phospholipase D from tobacco binds to microtubules and the plasma membrane

The organization of microtubule arrays in the plant cell cortex involves interactions with the plasma membrane, presumably through protein bridges. We have used immunochemistry and monoclonal antibody 6G5 against a candidate bridge protein, a 90-kD tubulin binding protein (p90) from tobacco BY-2 membranes, to characterize the protein and isolate the corresponding gene. Screening an Arabidopsis cDNA expression library with the antibody 6G5 produced a partial clone encoding phospholipase D (PLD), and a full-length gene was obtained by sequencing a corresponding expressed sequence tag clone. The predicted protein of 857 amino acids contains the active sites of a phospholipid-metabolizing enzyme and a Ca(2+)-dependent lipid binding domain and is identical to Arabidopsis PLD delta. Two amino acid sequences obtained by Edman degradation of the tobacco p90 are identical to corresponding segments of a PLD sequence from tobacco. Moreover, immunoprecipitation using the antibody 6G5 and tobacco BY-2 protein extracts gave significant PLD activity, and PLD activity of tobacco BY-2 membrane proteins was enriched 6.7-fold by tubulin-affinity chromatography. In a cosedimentation assay, p90 bound and decorated microtubules. In immunofluorescence microscopy of intact tobacco BY-2 cells or lysed protoplasts, p90 colocalized with cortical microtubules, and taxol-induced microtubule bundling was accompanied by corresponding reorganization of p90. Labeling of p90 remained along the plasma membrane when microtubules were depolymerized, although detergent extraction abolished the labeling. Therefore, p90 is a specialized PLD that associates with membranes and microtubules, possibly conveying hormonal and environmental signals to the microtubule cytoskeleton.

Screening for high utilizing somatizing patients using a prediction rule derived from the management information system of an HMO: a preliminary study

BACKGROUND

Somatization is a common, costly problem with great morbidity, but there has been no effective screening method to identify these patients and target them for treatment.

OBJECTIVES

We tested a hypothesis that we could identify high utilizing somatizing patients from a management information system (MIS) by total number of visits and what we termed "somatization potential," the percentage of visits for which ICD-9 primary diagnosis codes represented disorders in the musculoskeletal, nervous, or gastrointestinal systems or ill-defined complaints.

METHODS

We identified 883 high users from the MIS of a large staff model HMO as those having six or more visits during the year studied (65th percentile). A physician rater, without knowledge of hypotheses and predictors, then reviewed the medical records of these patients and identified somatizing patients (n = 122) and nonsomatizing patients (n = 761). In two-thirds of the population (the derivation set), we used logistic regression to refine our hypothesis and identify predictors of somatization available from the MIS: demographic data, all medical encounters, and primary diagnoses made by usual care physicians (ICD-9 codes). We then tested our prediction model in the remaining one-third of the population (the validation set) to validate its usefulness.

RESULTS

The derivation set contained the following significant correlates of somatization: gender, total number of visits, and percent of visits with somatization potential. The c-statistic, equivalent to the area under the ROC curve, was 0.90. In the validation set, the explanatory power was less with a still impressive c-statistic of 0.78. A predicted probability of 0.04 identified almost all somatizers, whereas a predicted probability of 0.40 identified about half of all somatizers but produced few false positives.

CONCLUSIONS

We have developed and validated a prediction model from the MIS that helps to distinguish chronic somatizing patients from other high utilizing patients. Our method requires corroboration but carries the promise of providing clinicians and health plan directors with an inexpensive, simple approach for identifying the common somatizing patient and, in turn, targeting them for treatment. The screener does not require clinicians' time.

A 90-kD phospholipase D from tobacco binds to microtubules and the plasma membrane

The organization of microtubule arrays in the plant cell cortex involves interactions with the plasma membrane, presumably through protein bridges. We have used immunochemistry and monoclonal antibody 6G5 against a candidate bridge protein, a 90-kD tubulin binding protein (p90) from tobacco BY-2 membranes, to characterize the protein and isolate the corresponding gene. Screening an Arabidopsis cDNA expression library with the antibody 6G5 produced a partial clone encoding phospholipase D (PLD), and a full-length gene was obtained by sequencing a corresponding expressed sequence tag clone. The predicted protein of 857 amino acids contains the active sites of a phospholipid-metabolizing enzyme and a Ca(2+)-dependent lipid binding domain and is identical to Arabidopsis PLD delta. Two amino acid sequences obtained by Edman degradation of the tobacco p90 are identical to corresponding segments of a PLD sequence from tobacco. Moreover, immunoprecipitation using the antibody 6G5 and tobacco BY-2 protein extracts gave significant PLD activity, and PLD activity of tobacco BY-2 membrane proteins was enriched 6.7-fold by tubulin-affinity chromatography. In a cosedimentation assay, p90 bound and decorated microtubules. In immunofluorescence microscopy of intact tobacco BY-2 cells or lysed protoplasts, p90 colocalized with cortical microtubules, and taxol-induced microtubule bundling was accompanied by corresponding reorganization of p90. Labeling of p90 remained along the plasma membrane when microtubules were depolymerized, although detergent extraction abolished the labeling. Therefore, p90 is a specialized PLD that associates with membranes and microtubules, possibly conveying hormonal and environmental signals to the microtubule cytoskeleton.

A 90-kD phospholipase D from tobacco binds to microtubules and the plasma membrane

The organization of microtubule arrays in the plant cell cortex involves interactions with the plasma membrane, presumably through protein bridges. We have used immunochemistry and monoclonal antibody 6G5 against a candidate bridge protein, a 90-kD tubulin binding protein (p90) from tobacco BY-2 membranes, to characterize the protein and isolate the corresponding gene. Screening an Arabidopsis cDNA expression library with the antibody 6G5 produced a partial clone encoding phospholipase D (PLD), and a full-length gene was obtained by sequencing a corresponding expressed sequence tag clone. The predicted protein of 857 amino acids contains the active sites of a phospholipid-metabolizing enzyme and a Ca(2+)-dependent lipid binding domain and is identical to Arabidopsis PLD delta. Two amino acid sequences obtained by Edman degradation of the tobacco p90 are identical to corresponding segments of a PLD sequence from tobacco. Moreover, immunoprecipitation using the antibody 6G5 and tobacco BY-2 protein extracts gave significant PLD activity, and PLD activity of tobacco BY-2 membrane proteins was enriched 6.7-fold by tubulin-affinity chromatography. In a cosedimentation assay, p90 bound and decorated microtubules. In immunofluorescence microscopy of intact tobacco BY-2 cells or lysed protoplasts, p90 colocalized with cortical microtubules, and taxol-induced microtubule bundling was accompanied by corresponding reorganization of p90. Labeling of p90 remained along the plasma membrane when microtubules were depolymerized, although detergent extraction abolished the labeling. Therefore, p90 is a specialized PLD that associates with membranes and microtubules, possibly conveying hormonal and environmental signals to the microtubule cytoskeleton.

Impairments of memory and learning in older adults exposed to polychlorinated biphenyls via consumption of Great Lakes fish

An association between in utero polychlorinated biphenyl (PCB) exposure and impaired childhood intellectual functioning has been reported, but the potential impact of PCB exposure during adulthood on intellectual functioning has received little attention. We assessed the impact of PCBs and other fish-borne contaminants on intellectual functioning in older adults. The subjects were 49- to 86-year-old Michigan residents recruited from an existing cohort. Fish eaters ate > 24 lb of sport-caught Lake Michigan fish per year and non-fish eaters ate < 6 lb of Lake Michigan fish per year. A battery of cognitive tests including tests of memory and learning, executive function, and visual-spatial function was administered to 180 subjects (101 fish eaters and 79 non-fish eaters). Blood samples were analyzed for PCBs and 10 other contaminants. We evaluated cognitive outcomes using multiple regression. PCBs and dichlorodiphenyl dichloroethene (DDE) were markedly elevated in fish eaters. After controlling for potential confounders PCB, but not DDE, exposure was associated with lower scores on several measures of memory and learning. These included the Weschler Memory Scale verbal delayed recall (p = 0.001), the semantic cluster ratio (p = 0.006), and list A, trial 1 (p = 0.037), from the California Verbal Learning Test. In contrast, executive and visual-spatial function were not impaired by exposure to either PCBs or DDE. In conclusion, PCB exposure during adulthood was associated with impairments in memory and learning, whereas executive and visual-spatial function were unaffected. These results are consistent with previous research showing an association between in utero PCB exposure and impairments of memory during infancy and childhood.

A comparison of the effects of lamotrigine on neuroma-induced action potential firing and normal behaviour in rat: implications for establishing a pre-clinical 'therapeutic index'

The effects of lamotrigine on rat neuroma and behavioural paradigms were evaluated to determine a pre-clinical therapeutic index. Lamotrigine blocked neuroma-induced burst pattern firing at a free plasma concentration of 13.7+/-1.7 microM (n=5). Oral dosing of lamotrigine (50-200 mg/kg) had no significant effects on behaviour but measurements of plasma concentrations of free drug showed non-linear oral absorption and lower than predicted drug levels (5-27 microM). Given intravenously (10-100 mg/kg), lamotrigine did affect behaviour at a free plasma concentration of 42.0 microM (n=2). By comparing free plasma concentrations, a therapeutic index of 3 was calculated, which is lower than published data based on comparing oral doses. We propose that a therapeutic index should only be derived with reference to plasma drug concentrations to prevent non-linear or incomplete drug absorption from confounding accurate estimation.

The effect of outliers on confidence interval procedures for cost-effectiveness ratios

Cost-effectiveness ratio (CER) is defined as the ratio of the difference in cost between a test and standard health care programme to the difference in benefit, respectively. Methods to obtain confidence intervals for CERs are either variants of Fieller's method (1954), or bootstrap methods. We study the effect of outliers in cost measures on the precision of confidence interval procedures for CERs. In particular the performance of the procedures under single and multiple case influential deletion diagnostics, respectively, are evaluated. Simulation studies suggest that the bias-corrected percentile bootstrap procedure gives better precision and coverage under either diagnostic.

Simple shear testing of parallel-fibered planar soft tissues

The simple shear test may provide unique information regarding the material response of parallel-fibered soft tissues because it allows the elimination of the dominant fiber material response from the overall stresses. However, inhomogeneities in the strain field due to clamping and free edge effects have not been documented. The finite element method was used to study finite simple shear of simulated ligament material parallel to the fiber direction. The effects of aspect ratio, clamping prestrain, and bulk modulus were assessed using a transversely isotropic, hyperelastic material model. For certain geometries, there was a central area of uniform strain. An aspect ratio of 1:2 for the fiber to cross-fiber directions provided the largest region of uniform strain. The deformation was nearly isochoric for all bulk moduli indicating this test may be useful for isolating solid viscoelasticity from interstitial flow effects. Results suggest this test can be used to characterize the matrix properties for the type of materials examined in this study, and that planar measurements will suffice to characterize the strain. The test configuration may be useful for the study of matrix, fiber-matrix, and fiber-fiber material response in other types of parallel-fibered transversely isotropic soft tissues.

The effect of subclinical Mycobacterium paratuberculosis infection on days open in Michigan, USA, dairy cows

A prospective cohort study design was used to evaluate the impact of subclinical Mycobacterium paratuberculosis infection on days open in a sample of Michigan dairy herds with a history of cows positive for M. paratuberculosis diagnosed by fecal culture. Participating herds were tested and productivity and reproduction records were monitored for 18 months. All cows > or = 24 months old were tested for M. paratuberculosis infection using the ELISA and radiometric fecal-culture (RFC) techniques. Test-negative cows were re-tested at the conclusion of the monitoring period. Multivariable regression models were used. Using both tests in parallel, the overall sample apparent prevalence for M. paratuberculosis infection was 41.8% (223/533 animals tested). Adjusting for diagnostic sensitivity and specificity, this resulted in a calculated sample true prevalence of 59.9%. ELISA-positive cows (on average) had a 28-day increase in days open when compared to ELISA-negative cows (p=0.02). The diagnostic method used to define a case altered the apparent association between paratuberculosis test status and days open. Fecal culture was a less-effective diagnostic tool for use in herds with a high prevalence of infected animals. The increase in days open in the ELISA-positive cows was an indication that perhaps reduced estrus expression or an increased post-partum anestrous period occurred in the subclinically infected ELISA-positive animals. This might have been due to a negative energy balance associated with M. paratuberculosis infection.

Impact of a deep saturation dive on semen quality

The demonstration dive 'Aurora' has provided an opportunity to study the impact of extreme hyperbaric conditions on male fertility. This operation involved a 33-day diving programme during which divers were exposed to a maximum pressure of 4.6 Mega Pascals (Mpa) for 7 days. At days - 4, + 27, + 34, + 82 and + 263 relative to the initiation of the dive, semen samples were analysed to determine the quality of spermatogenesis and the functional competence of the spermatozoa. A dramatic fall in semen quality was observed in association with the dive and by day + 82 the potential fertility of the men was seriously compromised as evidenced by oligoasthenoteratozoospermic semen profiles and the poor fertilizing potential of the spermatozoa. These studies indicate, for the first time, that the severe hyperbaric conditions associated with deep saturation dives have a profound effect on male reproductive function.

Power and sample assessments for tests of hypotheses on cost-effectiveness ratios

We address the issue of statistical power and sample size for cost-effectiveness studies. Tests of hypotheses on the cost-effectiveness ratio (CER) are constructed from the net cost and incremental effectiveness measures. When the difference in effectiveness is known, we derive formulae for statistical power and sample size assessments for one- and two-sided tests of hypotheses of the CER. We also construct a test of the joint hypothesis of cost-effectiveness and effectiveness and derive an expression connecting power and sample size. Our methods account for the correlation between cost and effectiveness and lead to smaller sample size requirements than comparative methods that ignore the correlation. The implications of our formulae for cost-effectiveness studies are illustrated through numerical examples. When compared with trials designed to demonstrate effectiveness alone, our results indicate that a trial appropriately powered to demonstrate cost-effectiveness might require sample sizes many times greater.

PCB congener profile in the serum of humans consuming Great Lakes fish

The State of Michigan has a long history of research into human exposure to environmental contaminants through consumption of recreationally caught fish. A large cohort of Lake Michigan residents who eat fish (fish-eaters) and those who do not eat fish (nonfish-eaters) established in 1980 served as the basis for the congener-specific polychlorinated biphenyl (PCB) exposure evaluation reported here. In this paper we present the serum PCB congener profile for a subset of this cohort who were over 50 years of age. Serum samples were collected in 1993-1995 and were evaluated by a dual column capillary column gas chromatography procedure capable of detecting over 90 PCB congeners. This evaluation demonstrated significant PCB exposure in the fish-eaters (mean serum PCB of 14.26 ppb; n = 101). This elevated exposure allowed the establishment of a detailed profile of the PCB congeners found in humans exposed by this route. Twenty-two congeners of varying concentrations were the most prevalent and constituted over 95% of the total PCB present in most subjects. Four congeners, 138/163 (2,2',3,4,4',5-PCB/2,3,3',4', 5,6-PCB), 180 (2,2',3,4,4',5,5'-PCB), and 153 (2,2',4,4',5,5'-PCB), accounted for 55-64% of the total PCB load. Other congeners, some of toxicologic significance, were also detected by this analytical protocol. Nonfish-eaters had lower total serum PCB levels (mean = 4. 56; n = 78), but the same general pattern of PCB congeners was present. It was demonstrated that careful selection of a subset of prevalent PCB congeners could provide a cost-effective assessment of exposure without losing critical scientific information.

Why most workers with occupational repetitive trauma do not file for workers' compensation

Despite the availability of no fault insurance for wage replacement and medical care costs, the majority of workers diagnosed with an occupational disease do not apply for workers' compensation. The objective of the study was to determine the reasons why workers diagnosed with work-related musculoskeletal disease did not apply for workers' compensation benefits. A cross-sectional study of 1598 individuals diagnosed with neck, upper extremity, and low back work-related musculoskeletal disease from April to June 1996 was performed. All individuals were interviewed over the telephone using a standardized questionnaire. The questionnaire included questions about the precipitating event; demographics; health limitations; mood; pain level; and attitudes toward their health care provider, fellow workers, management, work environment, and filing for workers' compensation. Whenever possible, standardized questions from previous surveys were used. The interviewed individuals with work-related musculoskeletal disease were reported by health care practitioners as required by the state of Michigan's occupational disease reporting law. Workers reported during 12 weeks in the spring of 1996 by a Michigan health care professional as having a neck, back, or upper extremity musculoskeletal disorder were eligible to participate. Among the 2703 reports received, 490 individuals could not be reached, 22 did not speak English, 12 had died or were too incapacitated by other medical conditions, and 581 refused. We interviewed 59% of all eligible workers and 73% of all workers who were reachable and capable of responding in English. Only 25% of workers diagnosed with musculoskeletal disease filed a workers' compensation claim. The factors significantly associated with filing a claim were (1) increased length of employment (> 21 years: odds ratio [OR], 3.01, 95% confidence interval [CI], 1.31 to 6.90); 11 to 20 years: OR, 2.34, 95% CI, 1.01 to 5.47; 6 to 10 years: OR, 1.76, 95% CI, 0.73 to 4.25; 1 to 5 years: OR, 2.36, 95% CI, 1.03 to 5.42; < 1 year: OR, 1.00; (2) lower annual income (< $40,000: OR, 1.75, 95% CI, 1.06 to 2.88 vs > or = $80,000: OR, 1.00); (3) workers' dissatisfaction with coworkers (OR, 1.76, 95% CI, 1.01 to 3.06); (4) physician restrictions on activity (OR, 2.16, 95% CI, 1.55 to 3.00); (5) type of physician providing treatment (specialist, including surgeon or orthopedist: OR, 3.63, 95% CI, 2.37 to 5.55); physical and occupational therapist: OR, 2.15, 95% CI, 1.35 to 3.43); family practitioner: OR, 1.33, 95% CI = 0.89 to 2.01; company physician: OR = 1.00); (6) off work > or = 7 days (OR, 14.85, 95% CI, 10.57 to 20.85); (7) decreased current health status (OR, 0.82, 95% CI, 0.70 to 0.96); and (8) increased severity of illness (OR, 1.24, 95% CI, 1.06 to 20.88). This study showed that only 25% of workers with a work-related musculoskeletal condition filed for workers' compensation and refutes the common perception that an individual with a work-related problem is likely to file a workers' compensation claim. The strongest predictors of who would file were those factors associated with the severity of the condition. Other factors were increasing length of employment, lower annual income, and worker dissatisfaction with coworkers. Our study population consisted mainly of unionized autoworkers, and our findings may not be generalizable to the total workforce.

Evidence-based guidelines for teaching patient-centered interviewing

In a rare study of effectiveness of an interviewing method, we previously reported a randomized controlled trial demonstrating that training in a step-by-step patient-centered interviewing method improved residents' knowledge, attitudes, and skills and had a consistently positive effect on trained residents' patients. For those who wish to use this evidence-based patient-centered method as a template for their own teaching, we describe here for the first time our training program--and propose that the training can be adapted for students, physicians, nurse practitioners, physician assistants, and other new learners as well. Training was skills-oriented and experiential, fostered positive attitudes towards patient-centered interviewing, and used a learner-centered approach which paid special attention to the teacher-resident relationship and to the resident's self-awareness. Skills training was guided by a newly identified patient-centered interviewing method that described the step-by-step use of specific behaviors.

Diagnosis of attention-deficit/hyperactivity disorder and use of psychotropic medication in very young children

CONTEXT

Increases in diagnosis and treatment of attention-deficit/hyperactivity disorder (ADHD) have elicited public and professional concern. Research suggests that this trend warrants the inclusion of previously underdiagnosed children and adults. It is not clear whether this trend includes young children.

OBJECTIVE

To identify patterns of diagnosis and treatment of ADHD in very young children over time.

DESIGN

Descriptive study of Michigan Medicaid claims data.

PATIENTS

Inclusion criteria included recorded ADHD diagnosis, continuous Medicaid eligibility during a 15-month period, and age 3 years or younger at the first date of service.

MAIN OUTCOME MEASURES

Diagnoses of ADHD, conditions commonly comorbid with ADHD, other chronic health conditions, and injuries; treatments such as psychological services and psychotropic medication; and the number of ambulatory visits.

RESULTS

We identified 223 children aged 3 years or younger diagnosed with ADHD. Many had conditions commonly comorbid with ADHD (44%), other chronic health conditions (41%), and injuries (40%). More than half received psychotropic medication (57%); fewer received psychological services (27%). Twenty-two different psychotropic medications were used. Patterns included more than 1 psychotropic medication (46%) in 30 combinations of simultaneous use and 44 combinations of sequential use. The mean number of ambulatory visits was 18.

CONCLUSIONS

Children aged 3 years or younger had ADHD diagnosed and received markedly variable psychotropic medication regimens. Little information is available to guide these practices. The presence of comorbid conditions and injuries attests to these children's vulnerability. Resources must be identified that will enable physicians to better respond to the compelling needs of these children and their families.

Phenobarbital compared with phenytoin for the treatment of neonatal seizures

BACKGROUND

Seizures occur in 1 to 2 percent of neonates admitted to an intensive care unit. The treatment is usually with either phenobarbital or phenytoin, but the efficacy of the two drugs has not been compared directly.

METHODS

From 1990 to 1995, we studied 59 neonates with seizures that were confirmed by electroencephalography. The neonates were randomly assigned to receive either phenobarbital or phenytoin intravenously, at doses sufficient to achieve free plasma concentrations of 25 microg per milliliter for phenobarbital and 3 microg per milliliter for phenytoin. Neonates whose seizures were not controlled by the assigned drug were then treated with both drugs. Seizure control was assessed by electroencephalographic criteria.

RESULTS

Seizures were controlled in 13 of the 30 neonates assigned to receive phenobarbital (43 percent) and 13 of the 29 neonates assigned to receive phenytoin (45 percent; P=1.00). When combined treatment is considered, seizure control was achieved in 17 (57 percent) of the neonates assigned to receive phenobarbital first and 18 (62 percent) of those assigned to receive phenytoin first (P=0.67). The severity of the seizures was a stronger predictor of the success of treatment than was the assigned agent. Neonates with mild seizures or with seizures that were decreasing in severity before treatment were more likely to have their seizures end, regardless of the treatment assignment.

CONCLUSIONS

Phenobarbital and phenytoin are equally but incompletely effective as anticonvulsants in neonates. With either drug given alone, the seizures were controlled in fewer than half of the neonates.

Phenobarbital compared with phenytoin for the treatment of neonatal seizures

BACKGROUND

Seizures occur in 1 to 2 percent of neonates admitted to an intensive care unit. The treatment is usually with either phenobarbital or phenytoin, but the efficacy of the two drugs has not been compared directly.

METHODS

From 1990 to 1995, we studied 59 neonates with seizures that were confirmed by electroencephalography. The neonates were randomly assigned to receive either phenobarbital or phenytoin intravenously, at doses sufficient to achieve free plasma concentrations of 25 microg per milliliter for phenobarbital and 3 microg per milliliter for phenytoin. Neonates whose seizures were not controlled by the assigned drug were then treated with both drugs. Seizure control was assessed by electroencephalographic criteria.

RESULTS

Seizures were controlled in 13 of the 30 neonates assigned to receive phenobarbital (43 percent) and 13 of the 29 neonates assigned to receive phenytoin (45 percent; P=1.00). When combined treatment is considered, seizure control was achieved in 17 (57 percent) of the neonates assigned to receive phenobarbital first and 18 (62 percent) of those assigned to receive phenytoin first (P=0.67). The severity of the seizures was a stronger predictor of the success of treatment than was the assigned agent. Neonates with mild seizures or with seizures that were decreasing in severity before treatment were more likely to have their seizures end, regardless of the treatment assignment.

CONCLUSIONS

Phenobarbital and phenytoin are equally but incompletely effective as anticonvulsants in neonates. With either drug given alone, the seizures were controlled in fewer than half of the neonates.

Practice guidelines and late-life depression assessment in long-term care

To determine how well nursing home physicians believe they can detect and treat depression, we conducted a national survey, eliciting a 63% response rate. More than 75% of respondents believed they detected and treated depression well. Excellent depression training (vs "good," "fair," "poor/none") was associated with better self-reported recognition (odds ratio [OR] 14.25; 95% confidence interval [CI] 1.81, 111.93) and treatment skills (OR 6.72; 95% CI 1. 91, 23.64). Screening tool use predicted greater self-assessed detection (OR 1.89; 95% CI 0.92, 3.87) and treatment competency (OR 2.00; 95% CI 1.14, 3.50). Practice guideline awareness was associated with greater self-reported treatment competency (OR 2.47; 95% CI 1.56, 3.91).

Factors influencing recovery from and duration of lameness in Michigan (USA) horses

The objective of this study was to identify factors that may affect recovery from and duration of a case of lameness in a stratified random sample of Michigan horses. This was done using data from Phase-II of the Michigan equine monitoring system (MEMS Phase-II), the equine health-monitoring study [Kaneene et al., Prev. Vet. Med. 29 (1997b) 277-292; Ross and Kaneene, Prev. Vet. Med. 28 (1996a) 209-224; Ross and Kaneene, Prev. Vet. Med. 29 (1996b) 59-75; Ross et al., Am. J. Vet. Res. 59 (1997) 23-29]. In this study, statistical modelling was conducted to evaluate risk factors affecting recovery from and duration of lameness using multivariable logistic regression and Cox's proportional hazards regression, respectively. Of 357 incident lameness cases reported during MEMS Phase-II, 280 (78.6%) were reported to have recovered. The median duration of a lameness case was 18 days (1st quartile (Q): 1, maximum (Max): 360). A total of 296 of 357 (82.9%) incident lameness cases received some type of treatment. Of 619 total treatments used, 329 (53.2%) were administered, conducted or applied by a veterinarian. Horses experiencing other types of lameness were less likely to recover than those experiencing hoof lameness (odds ratio (OR) = 0.48; 95% CI: 0.25, 0.93). Horses that had participated in exercise-related activities during the study period and prior to the lameness were more likely to recover (OR = 1.91; 95% CI: 1.05, 3.50). Treatment of the lameness was associated with an increased likelihood of recovery (OR = 1.82; 95% CI: 0.97, 3.45). Cases with a veterinarian involved in the diagnosis were associated with a decreased risk of recovery (OR = 0.48; 95% CI: 0.27, 0.84) and a longer duration lameness (HR = 0.58; 95% CI: 0.45, 0.73)--which might indicate that these cases were more complex or severe. Although cases treated for lameness were more likely to recover (OR = 1.82; 95% CI: 1.05, 3.50), treatment was not associated with lameness duration (HR = 0.58; 95% CI: 0.45, 0.73).

Skin cancer prevention and detection practices in a Michigan farm population following an educational intervention

Farmers face an increased risk of skin cancer, presumed to be secondary to their increased occupational exposure to sunlight. This study examines skin cancer prevention and detection beliefs and practices among adult farmers in defined control and comparison farming communities in four contiguous counties of Michigan, before and after a community-based educational intervention. The educational intervention included mailing packets containing information on skin cancer risks and community sources for screening, disseminating articles in local newspapers on skin cancer prevention and control measures, and providing information and screening at local county fairs and agricultural community fairs. The responses of 2,999 survey participants were analyzed to identify the interrelationships among their beliefs and their descriptions of their (primary preventive) self-care and professional medical care seeking (for detection and treatment) practices. Factors associated with the likelihood of skin cancer screening and with measures of knowledge and practices associated with medical care of skin cancer were examined. The intervention appeared to improve the practice of preventive behaviors and seeking medical care.

Motor function in aging Great Lakes fisheaters

Exposure to contaminants in Great Lakes fish has been linked to impaired neuropsychological functioning in children, but neurological function of exposed adults has not been evaluated. This report describes a cross-sectional analysis of the effects of PCB/DDE exposure from contaminated fish on fine motor function in older adults. The subjects were 50-90-year-old Michigan residents who were members of a previously established study cohort. Fisheaters ate 24 lbs or more of sport-caught Lake Michigan fish/year at the time they were originally recruited in 1980-1982. Age- and sex-matched non-fisheaters ate 6 or fewer lbs/year. Outcome measures were scores on the Static Motor Steadiness Test (SMST) and Grooved Pegboard Test (GPT). PCB/DDE exposure was determined through serum analyses performed at the time of recruitment into the present study in 1993-1995. Because of the high correlation between serum PCB and DDE levels in this sample (Spearman r=0.64, P<0.0001), the effects of the two contaminants were assessed jointly using a single derived exposure variable=Low=both PCB and DDE at or below the medians of their respective distributions, intermediate=PCB and/or DDE in the third quartile, and high=PCB and/or DDE in the upper quartile. In unadjusted analyses, high exposure to PCBs/DDE was associated with significantly poorer performance on the GPT (P=0.03). However, in the multiple regression model, age and gender emerged as the most significant factors affecting GPT scores, and exposure to PCB/DDE was not significant. Performance on the SMST was not related to PCB/DDE exposure in initial unadjusted analyses, but performance with the dominant hand was marginally (P=0.052) associated with exposure in the final model. Scores on the SMST improved slightly as PCB/DDE exposure increased. A similar trend was not observed for the nondominant hand (P=0.46). These findings suggest that PCB/DDE exposure from Great Lakes fish has not significantly impaired hand steadiness or visual-motor coordination in this sample of older adults.

The effectiveness of intensive training for residents in interviewing. A randomized, controlled study

BACKGROUND

Interviewing and the physician-patient relationship are crucial elements of medical care, but residencies provide little formal instruction in these areas.

OBJECTIVE

To determine the effects of a training program in interviewing on 1) residents' attitudes toward and skills in interviewing and 2) patients' physical and psychosocial well-being and satisfaction with care.

DESIGN

Randomized, controlled study.

SETTING

Two university-based primary care residencies.

PARTICIPANTS

63 primary care residents in postgraduate year 1.

INTERVENTION

A 1-month, full-time rotation in interviewing and related psychosocial topics.

MEASUREMENTS

Residents and their patients were assessed before and after the 1-month rotation. Questionnaires were used to assess residents' commitment to interviewing and psychosocial medicine, estimate of the importance of such care, and confidence in their ability to provide such care. Knowledge of interviewing and psychosocial medicine was assessed with a multiple-choice test. Audiotaped interviews with real patients and videotaped interviews with simulated patients were rated for specific interviewing behaviors. Patients' anxiety, depression, and social dysfunction; role limitations; somatic symptom status; and levels of satisfaction with medical visits were assessed by questionnaires and telephone interviews.

RESULTS

Trained residents were superior to untrained residents in knowledge (difference in adjusted post-test mean scores, 15.7% [95% CI, 11% to 20%]); attitudes, such as confidence in psychological sensitivity (difference, 0.61 points on a 7-point scale [CI, 0.32 to 0.91 points]); somatization management (difference, 0.99 points [CI, 0.64 to 1.35 points]); interviewing of real patients (difference, 1.39 points on an 11-point scale [CI, 0.32 to 2.45 points]); and interviewing (data gathering) of simulated patients (difference, 2.67 points [CI, 1.77 to 3.56 points]). Mean differences between the study groups were consistently in the appropriate direction for patient satisfaction and patient well-being, but effect sizes were too small to be considered meaningful.

CONCLUSION

An intensive 1-month training rotation in interviewing improved residents' knowledge about, attitudes toward, and skills in interviewing.

Survival analysis of risk factors associated with the occurrence of lameness in a Michigan horse population

OBJECTIVE

To evaluate the associations of operation and individual animal-level risk factors with occurrence of lameness in the Michigan horse population.

SAMPLE POPULATION

3,925 horses monitored from 138 randomly selected Michigan operations for a total of 814,753 horse-days.

PROCEDURE

All horses monitored < 60 days were eliminated from the source population. From the remaining horses, a prospective unmatched case-control study population was generated that included all cases and a random sample of noncases. Analysis of risk factors associated with occurrence of lameness was conducted, using Cox's proportional hazards regression model.

RESULTS

Horses in larger operations, compared with horses in the first operation size quartile, were associated with decreased risk of lameness (2nd quartile [Q]: hazard ratio [HR] = 0.57; 95% confidence interval [CI]: 0.36, 0.91; 3rd Q: HR = 0.74; 95% CI: 0.49, 1.13; 4th Q: HR = 0.46; 95% CI: 0.28, 0.76). Compared with mares, stallions (HR = 1.90; 95% CI: 1.17, 3.07) and geldings (HR = 1.46; 95% CI: 1.02, 2.09) were at increased risk of lameness. Compared with horses used for breeding purposes only, those participating in exercise or performance-related activities including racing (HR = 4.70; 95% CI: 1.70, 13.03) and showing (HR = 2.80; 95% CI: 1.07, 7.28) also were at increased risk of lameness.

CONCLUSIONS

Comparison of these results with those conducted using multivariable logistic regression strengthens the argument that there is decreased risk of lameness for horses in larger operations and increased risk of lameness for active horses. Additionally, results of this analysis suggested that stallions and geldings are at increased risk of lameness, compared with mares.

CLINICAL RELEVANCE

Lameness prevention strategies in the horse industry should focus principally on horses participating in exercise or performance-related activities, including racing and showing, on male horses, and on horses stabled in smaller operations.

The association of serum nonesterified fatty acids and cholesterol, management and feeding practices with peripartum disease in dairy cows

A prospective study was conducted to determine the relationship of serum nonesterified fatty acids (NEFA) and cholesterol concentrations and herd management practices to the occurrence of metritis, mastitis and retained placenta in Holstein cows in Michigan. Serum samples were collected once prepartum and once postpartum from 257 cows. Animals were under observation for disease occurrence from the date of calving until 3 months postpartum. Metabolic variables used were (1) prepartum only; (2) postpartum only; (3) the NEFA/cholesterol ratio for both pre- and postpartum samples. Management variables included maternity management, feed management, and factors such as season and parity. Multivariable logistic models with random-effect terms to account for the herd effect were used for data analysis. Results showed that: (1) metabolic events associated with energy insufficiency-increased fat mobilization and serum lipoprotein metabolism-were related to increased risk of metritis and retained placenta; (2) higher energy consumption during the last weeks of the dry period might reduce disease risk at parturition; (3) serum NEFA and cholesterol concentrations have potential as indicators of disease risk in dairy cows.

A standard protocol for blood pressure measurement in the newborn

OBJECTIVES

Improvements in neonatal care have resulted in increasing survival of extremely premature infants whose hospital course often runs into weeks or months. Some interventions during the acute care of these neonates, such as umbilical catheterization and use of steroids, not infrequently result in elevation of blood pressure (BP). It is, therefore, essential that these infants be monitored accurately for possible hypertension during their convalescence. Unfortunately, normative data on BP in this population are scant and comparison of data from various studies is hampered by methodologic differences in design. Studies in adults address the necessity for a restful state, adopting a comfortable position, and attempts to reduce the startle response to initial cuff inflation. Studies in the newborn using the oscillometric technique have not addressed these concerns. A standard BP measurement protocol was studied to determine the effect of ensuring a restful state, startle response to cuff inflation, and infant position on BP in clinically stable low birth weight infants after the first week of life.

STUDY DESIGN

The Dianamap oscillometer was used to measure BP in infants with a birth weight <2500 g between 7 and 42 days postnatal age. Each infant was studied only once when they were clinically stable. BP was measured in two positions, prone and supine, in random order. Infants were studied at least 11/2 hours after their last feeding or medical intervention. An appropriate sized cuff was applied to the right upper arm and the infant was positioned according to randomization. The infant was then left undisturbed for at least 15 minutes or until the infant was sleeping or in a quiet awake state. Three successive BP recordings were taken at 2-minute intervals. The infant's position was then reversed and another 15 minutes of quiet time was allowed. Thereafter, a second set of three successive BP recordings were obtained. The most recent routine nursing BP measurement was also recorded. Data were analyzed using analysis of variance and are presented as means and standard errors of the mean.

RESULTS

Sixty-four infants were studied. Birth weights ranged from 901 to 2423 g and gestational ages from 26 to 37 weeks. Overall, mean BP was significantly lower in the prone than supine positions (45.7 +/- 0.7 vs 47.8 +/- 0.8 mm Hg, P < .002). In either position, the first measurement was significantly higher than the third (average difference was 3 mm Hg, P < .003). In general, the relationships among position and order of measurement were similar for systolic and diastolic BP. Mean BPs obtained by routine nurse measurements were significantly higher than those in either position using our standard protocol (54.4 vs 47.0 or 49.1 mm Hg, P < .003). Moreover, the routine nurse measurements varied more widely than did those obtained using the standard protocol. The standard deviation for the routine mean BP measurements by nurses was 11.4 compared with 6.8 and 8.2 for the first measurements in the prone and supine positions, respectively, with the standard protocol. The mean BP measurements made in the supine position (the highest measurements obtained) using the standard protocol were also significantly lower than published values: 57 of 64 measurements were less than the average mean BP for age described by Tan (J Pediatr. 1988; 112:266-270).

CONCLUSION

The statistically significant difference between the prone and supine position and among successive measurements in each position are not clinically relevant. The clinically significant differences between measurements obtained with this standard protocol and routine nursing measurements or published data are the result of ensuring a restful state after cuff application. We believe that measurements thus obtained are more representative of true resting BPs in these infants. (ABSTRACT TRUNCATED)

Neuropsychological assessment of an aging population of Great Lakes fisheaters

Because of the decline in central nervous system function that occurs with age, older people may be at greater risk of neurological dysfunction following exposure to neurotoxic contaminants in the environment. This study was designed to assess the neuropsychological functioning of a group of 50-90-year-old fisheaters exposed to polychlorinated biphenyls (PCBs) through Great Lakes fish consumption, and a group of age- and sex-matched nonfisheaters selected from the Michigan Department of Public Health's established cohort of fisheaters and nonfisheaters. A neuropsychological assessment battery, demographic interview, and fish consumption questionnaire were developed and piloted on similarly aged men and women in the Lansing and Detroit, Michigan, areas. The assessment battery included tests of motor function, memory and learning, executive functions, and visual-spatial functions, and took approximately two hours to administer. Most of the tests included in the battery have been shown to be sensitive to subtle, age-related declines in cognitive and motor function. The demographic questionnaire included questions on a number of important control variables that could influence the neuropsychological end points that were assessed in the study. These included demographic background, alcohol consumption, tobacco use, prescription and nonprescription drug use, medical history (including psychiatric illnesses), employment history, and activity level. The fish consumption questionnaire asked about historical and current consumption of specific fish species from each of the Great Lakes and its tributaries and was based on the fish consumption advisories published in the 1992 Michigan Fishing Guide. The questionnaire also asked about consumption of wild game, fish preparation and cooking methods, serving size, and changes in fish consumption patterns over time. After each subject completed the neuropsychological assessment, demographic interview, and fish consumption questionnaire, a blood sample was collected for analysis of PCBs, dichloro diphenyl dichloroethene (DDE), and ten other contaminants frequently detected in Great Lakes fish. Subject recruitment for the study began in July 1993 and was completed in November 1995. The data will be analyzed in two steps: first, to assess differences in confounding variables between fisheaters and nonfisheaters; and secondly, to determine the independent effects of Great Lakes fish consumption, as well as serum PCB and DDE levels, on cognitive and motor function after controlling for all identified covariates. Three indices of PCB exposure-total PCBs, total ortho-substituted PCBs and total coplanar PCBs-will be assessed. These studies should shed light on three questions: 1) Does consumption of contaminated fish from the Great Lakes exacerbate or accelerate the normal age-related decline in cognitive and motor function? 2) Do serum PCB or DDE concentrations predict the degree of behavioral dysfunction? and 3) If PCB exposure is related to behavioral outcomes, which class of PCB congeners, ortho-substituted or coplanar, are responsible for the cognitive and motor deficits?

Total hip replacement: the current perspective after 37 years

The first hip replacements of the modern era were performed by Sir John Charnley in 1959,using poly- tetrafluoroethylene for the acetabulum and polymethylmethacrylate cement to secure the stainless steel femoral component. These initial operations were not a success due to excessive wear of the PTFE bearing surface. The operation was not acknowledged to be the success it is today until 1962when Charnley switched to using high-density polyethylene for the acetabular component and the "low-friction arthroplasty" was introduced.' This prosthesis has remained the "gold standard" until the present day with relatively few changes to the original concept, and with considerable success with published results in excess of 20 years.'

The use of methylphenidate in Michigan

OBJECTIVE

To describe the epidemiologic findings associated with the use of methylphenidate hydrochloride among children aged 0 to 19 years in Michigan.

DESIGN

A population-based data set of all prescriptions filed with the Michigan Triplicate Prescription Program during February and March 1992 was analyzed, maintaining complete anonymity.

SETTING

State of Michigan.

PARTICIPANTS

All patients receiving a prescription for methylphenidate who are residents of Michigan, and all physicians prescribing methylphenidate.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Descriptive data.

RESULTS

Eleven of 1000 Michigan residents between the ages of 0 and 19 years received a prescription for methylphenidate during the study period. Eighty-four percent were boys. Boys aged 10 or 11 years received more prescriptions for methylphenidate than any other age group--43 per 1000. The number of children receiving prescriptions for methylphenidate ranged from 2.5 to 28 per 1000. The range for boys aged 10 or 11 years was from 9.6 to 117 per 1000. Primary care physicians wrote 84% of all prescriptions; pediatricians wrote 59% of the prescriptions for patients younger than 20 years old. Half of the prescriptions written by pediatricians were written by 5% of the pediatricians in the state.

CONCLUSIONS

Michigan has been among the states with the highest per capita consumption of methylphenidate for the past 10 years. The major use of methylphenidate is for treatment of attention deficit hyperactivity disorder. The number of boys in Michigan aged 10 or 11 years who were treated with methylphenidate was similar to the national prevalence of the disorder, 3% to 5%. A tenfold variation was noted in the percentage of children medicated when the data were analyzed by county. Relatively few pediatricians account for the largest proportion of prescriptions. Future studies are needed to link the use of methylphenidate with diagnostic and treatment considerations in attention deficit hyperactivity disorder.

Mammography usage and knowledge about breast cancer in a Michigan farm population before and after an educational intervention

The purpose of this study was to identify factors associated with the use of mammography screening in a farm population, before and after a community-based educational intervention. The educational intervention included sending individual mailings containing information about breast cancer risk and community sources for screening, and providing information and screening at local county fairs and agricultural community fairs. The authors used multivariate analytic methods to analyze the responses, reported by 1,545 women, to discern the roles of sociodemographic, attitudinal, and knowledge variables in this population's breast cancer screening practices. Results showed that the rural participants in both the intervention and the control communities demonstrated significant changes in knowledge and attitudes about breast cancer. Mammography usage was significantly higher among women who had higher scores on the knowledge and awareness assessments. Education--rather than income, insurance coverage, or family history of breast cancer--emerged in multivariate analyses as the most significant predictor of knowledge and awareness score levels associated with greater use of mammography. Implications of this study include support for education that emphasizes the benefits of early detection of breast cancer for all women.

Screening for congenital dislocation of the hip by physiotherapists. Results of a ten-year study

We report a prospective study of the feasibility of employing specially trained physiotherapists to screen neonates for congenital dislocation of the hip. During ten years 42,241 babies were screened, using clinical tests; 255 were diagnosed and treated by a Pavlik harness. In the same period 13 children presented late with congenital dislocation of the hip which had not been detected by the screening programme.

Screening for congenital dislocation of the hip by physiotherapists. Results of a ten-year study

We report a prospective study of the feasibility of employing specially trained physiotherapists to screen neonates for congenital dislocation of the hip. During ten years 42,241 babies were screened, using clinical tests; 255 were diagnosed and treated by a Pavlik harness. In the same period 13 children presented late with congenital dislocation of the hip which had not been detected by the screening programme.

Risk-efficient estimation of the mean exponential survival time under random censoring

The paper proposes a sequential estimator theta of the parameter theta of an exponential distribution when the data are censored. It is shown that theta is asymptotically risk efficient when the loss is measured by the squared error of estimation of theta plus a linear function of the number of observations and that theta is asymptotically normal as the cost per observation goes to zero.

Postsynaptic alpha 1-and alpha 2-adrenoceptor involvement in the vascular responses to neuronally released and exogenous noradrenaline in the hindlimb of the dog and cat

The contribution of postsynaptic alpha 1-and alpha 2-adrenoceptors to vascular responses was investigated in the blood perfused hindlimbs of pentobarbitone-anaesthetised dogs and chloralose-anaesthetised cats. Responses were obtained to sympathetic nerve stimulation, noradrenaline, phenylephrine and UK-14,304. In the dog and cat hindlimbs, the response to phenylephrine was reduced by the selective alpha 1-adrenoceptor antagonist, prazosin, while that to UK-14,304, in the dog, was reduced by the alpha 2-adrenoceptor antagonist, rauwolscine. Responses to noradrenaline and sympathetic nerve stimulation were only partially blocked by prazosin in both the dog and cat, but were further reduced by the addition of rauwolscine. These results suggest that the hindlimb vasculature of the dog and cat responds to neuronally released, as well as exogenous, noradrenaline by activation of both postsynaptic alpha 1- and alpha 2-adrenoceptors.