Morphology and the gradient of a symmetric potential predict gait transitions of dogs.

Gaits and gait transitions play a central role in the movement of animals. Symmetry is thought to govern the structure of the nervous system, and constrain the limb motions of quadrupeds. We quantify the symmetry of dog gaits with respect to combinations of bilateral, fore-aft, and spatio-temporal symmetry groups. We tested the ability of symmetries to model motion capture data of dogs walking, trotting and transitioning between those gaits. Fully symmetric models performed comparably to asymmetric with only a [Formula: see text] increase in the residual sum of squares and only one-quarter of the parameters. This required adding a spatio-temporal shift representing a lag between fore and hind limbs. Without this shift, the symmetric model residual sum of squares was [Formula: see text] larger. This shift is related to (linear regression, [Formula: see text], [Formula: see text]) dog morphology. That this symmetry is respected throughout the gaits and transitions indicates that it generalizes outside a single gait. We propose that relative phasing of limb motions can be described by an interaction potential with a symmetric structure. This approach can be extended to the study of interaction of neurodynamic and kinematic variables, providing a system-level model that couples neuronal central pattern generator networks and mechanical models.

Longitudinal quasi-static stability predicts changes in dog gait on rough terrain.

Legged animals utilize gait selection to move effectively and must recover from environmental perturbations. We show that on rough terrain, domestic dogs, Canis lupus familiaris, spend more time in longitudinal quasi-statically stable patterns of movement. Here, longitudinal refers to the rostro-caudal axis. We used an existing model in the literature to quantify the longitudinal quasi-static stability of gaits neighbouring the walk, and found that trot-like gaits are more stable. We thus hypothesized that when perturbed, the rate of return to a stable gait would depend on the direction of perturbation, such that perturbations towards less quasi-statically stable patterns of movement would be more rapid than those towards more stable patterns of movement. The net result of this would be greater time spent in longitudinally quasi-statically stable patterns of movement. Limb movement patterns in which diagonal limbs were more synchronized (those more like a trot) have higher longitudinal quasi-static stability. We therefore predicted that as dogs explored possible limb configurations on rough terrain at walking speeds, the walk would shift towards trot. We gathered experimental data quantifying dog gait when perturbed by rough terrain and confirmed this prediction using GPS and inertial sensors (n=6, P<0.05). By formulating gaits as trajectories on the n-torus we are able to make tractable the analysis of gait similarity. These methods can be applied in a comparative study of gait control which will inform the ultimate role of the constraints and costs impacting locomotion, and have applications in diagnostic procedures for gait abnormalities, and in the development of agile legged robots.

Population genetics of invasive common carp Cyprinus carpio L. in coastal drainages in eastern Australia.

The common carp Cyprinus carpio introduced in two drainages in eastern Australia are largely descended from European common carp, and in a third drainage they descend largely from East Asian common carp. The partial genetic differentiation among the species in those drainages is consistent with their origins.

Population genetics and management units of invasive common carp Cyprinus carpio in the Murray-Darling Basin, Australia.

Common carp Cyprinus carpio were introduced into Australia on several occasions and are now the dominant fish in the Murray-Darling Basin (MDB), the continent's largest river system. In this study, variability at 14 microsatellite loci was examined in C. carpio (n = 1037) from 34 sites throughout the major rivers in the MDB, from 3 cultured populations, from Prospect Reservoir in the Sydney Basin and from Lake Sorrell in Tasmania. Consistent with previous studies, assignment testing indicated that the Boolara, Yanco and koi strains of C. carpio are present in the MDB. Unique to this study, however, the Prospect strain was widely distributed throughout the MDB. Significant genetic structuring of populations (Fisher's exact test, AMOVA and distribution of the different strains) amongst the MDB sub-drainages was detected, and was strongly associated with contemporary barriers to dispersal and population history. The distributions of the strains were used to infer the history of introduction and spread of C. carpio in the MDB. Fifteen management units are proposed for control programmes that have high levels of genetic diversity, contain multiple interbreeding strains and show no evidence of founder effects or recent population bottlenecks.

Microevolution and mega-icebergs in the Antarctic.

Microevolution is regarded as changes in the frequencies of genes in populations over time. Ancient DNA technology now provides an opportunity to demonstrate evolution over a geological time frame and to possibly identify the causal factors in any such evolutionary event. Using nine nuclear microsatellite DNA loci, we genotyped an ancient population of Adélie penguins (Pygoscelis adeliae) aged approximately 6,000 years B.P. Subfossil bones from this population were excavated by using an accurate stratigraphic method that allowed the identification of individuals even within the same layer. We compared the allele frequencies in the ancient population with those recorded from the modern population at the same site in Antarctica. We report significant changes in the frequencies of alleles between these two time points, hence demonstrating microevolutionary change. This study demonstrates a nuclear gene-frequency change over such a geological time frame. We discuss the possible causes of such a change, including the role of mutation, genetic drift, and the effects of gene mixing among different penguin populations. The latter is likely to be precipitated by mega-icebergs that act to promote migration among penguin colonies that typically show strong natal return.

Albumin administration--what is the evidence of clinical benefit? A systematic review of randomized controlled trials.

BACKGROUND AND OBJECTIVE: The advantages of albumin over less costly alternative fluids continue to be debated. Meta-analyses focusing on survival have been inconclusive, and other clinically relevant end-points have not been systematically addressed. We sought to determine whether albumin confers significant clinical benefit in acute illness compared with other fluid regimens. METHODS: Database searches (MEDLINE, EMBASE, Cochrane Library) and other methods were used to identify randomized controlled trials comparing albumin with crystalloid, artificial colloid, no albumin or lower-dose albumin. Major findings for all end-points were extracted and summarized. A quantitative meta-analysis was not attempted. RESULTS: Seventy-nine randomized trials with a total of 4755 patients were included. No significant treatment effects were detectable in 20/79 (25%) trials. In cardiac surgery, albumin administration resulted in lower fluid requirements, higher colloid oncotic pressure, reduced pulmonary oedema with respiratory impairment and greater haemodilution compared with crystalloid and hydroxyethylstarch increased postoperative bleeding. In non-cardiac surgery, fluid requirements, and pulmonary and intestinal oedema were decreased by albumin compared with crystalloid. In hypoalbuminaemia, higher doses of albumin reduced morbidity. In ascites, albumin reduced haemodynamic derangements, morbidity and length of stay and improved survival after spontaneous bacterial peritonitis. In sepsis, albumin decreased pulmonary oedema and respiratory dysfunction compared with crystalloid, while hydroxyethylstarch induced abnormalities of haemostasis. Complications were lowered by albumin compared with crystalloid in burn patients. Albumin-containing therapeutic regimens improved outcomes after brain injury. CONCLUSIONS: Albumin can bestow benefit in diverse clinical settings. Further trials are warranted to delineate optimal fluid regimens, in particular indications.

Dietary intake, eating behavior, and physical activity-related determinants of high body mass index in rural communities in Wyoming, Montana, and Idaho.

OBJECTIVE: To assess the relation between body mass index (BMI) levels and various lifestyle variables related to physical activity and specific characteristics of a healthy eating pattern, using baseline cross-sectional data from the Wellness IN the Rockies project. SUBJECTS: A total of 928 males and 889 females, aged 18-99 y, recruited from six rural communities in Wyoming, Montana, and Idaho. MEASUREMENTS: Using BMI as the criterion, overweight was defined as a BMI >or=25 kg/m(2) and obesity was defined as a BMI >or=30 kg/m(2). All participants in this study completed a questionnaire that elicited sociodemographic information, self-reported height and weight, and data related to specific dietary intakes, eating-related behaviors, and physical activity behaviors and perceptions. RESULTS: Prevalence of overweight was 70% in men and 59% in women. Increased likelihood of overweight or obesity was associated with greater frequency of the following: drinking sweetened beverages such as soft drinks/soda pop, ordering supersized portions, eating while doing other activities, and watching television. Other predictors were lower frequency of participation in physical activity and the perception of not getting as much exercise as needed. CONCLUSIONS: The increased probability of having a high BMI in individuals who more often eat while doing another activity appears to be a novel finding that will need to be substantiated by additional research. The finding that the vast majority of overweight and obese respondents believed that they do not get as much exercise as needed strengthens the assertion that finding ways to increase participation in physical activity should remain a high priority in obesity prevention and intervention efforts at the community and individual levels.

The relationship between the stages of change for exercise and health insurance costs.

OBJECTIVE: To determine the relationship between the stages of exercise participation and health insurance costs. METHODS: A hurdle model was used to examine health survey and health insurance costs data by stage of exercise participation. RESULTS: Employees classified in the maintenance stage (regular exercisers) of exercise adoption had lower costs and a lower probability of being classified in the high-cost group than did employees classified in the other stages of change for exercise participation. CONCLUSION: This study offers evidence that the health insurance of individuals classified in the maintenance stage of exercise costs less than does that of individuals classified in other stages of exercise adoption.

Deaths attributed to pediatric complex chronic conditions: national trends and implications for supportive care services.

BACKGROUND: Children with complex chronic conditions (CCCs) might benefit from pediatric supportive care services, such as home nursing, palliative care, or hospice, especially those children whose conditions are severe enough to cause death. We do not know, however, the extent of this population or how it is changing over time. OBJECTIVES: To identify trends over the past 2 decades in the pattern of deaths attributable to pediatric CCCs, examining counts and rates of CCC-attributed deaths by cause and age (infancy: <1 year old, childhood: 1-9 years old, adolescence or young adulthood: 10-24 years old) at the time of death, and to determine the average number of children living within the last 6 months of their lives. DESIGN/METHODS: We conducted a retrospective cohort study using national death certificate data and census estimates from the National Center for Health Statistics. Participants included all people 0 to 24 years old in the United States from 1979 to 1997. CCCs comprised a broad array of International Classification of Diseases, Ninth Revision codes for cardiac, malignancy, neuromuscular, respiratory, renal, gastrointestinal, immunodeficiency, metabolic, genetic, and other congenital anomalies. Trends of counts and rates were tested using negative binomial regression. RESULTS: Of the 1.75 million deaths that occurred in 0- to 24-year-olds from 1979 to 1997, 5% were attributed to cancer CCCs, 16% to noncancer CCCs, 43% to injuries, and 37% to all other causes of death. Overall, both counts and rates of CCC-attributed deaths have trended downward, with declines more pronounced and statistically significant for noncancer CCCs among infants and children, and for cancer CCCs among children, adolescents, and young adults. In 1997, deaths attributed to all CCCs accounted for 7242 infant deaths, 2835 childhood deaths, and 5109 adolescent deaths. Again, in 1997, the average numbers of children alive who would die because of a CCC within the ensuing 6-month period were 1097 infants, 1414 children, and 2548 adolescents or young adults. CONCLUSIONS: Population-based planning of pediatric supportive care services should use measures that best inform our need to provide care for time-limited events (perideath or bereavement care) versus care for ongoing needs (home nursing or hospice). Pediatric supportive care services will need to serve patients with a broad range of CCCs from infancy into adulthood.

Mental health issues in the workplace: a case for a new managerial approach.

Anger, stress, and depression in the workplace are growing concerns among management. Traditionally, health outcomes have functioned under the realm of workplace health professionals. This study assessed whether a traditional worksite health promotion program had an impact on mental health factors. The results suggested that worksite health promotion programs play a limited role in ameliorating work-related mental health outcomes. Rather, management must play a greater role in addressing workplace stress, anger, and depression.

Patient-borne memory device facilitates "point of care" data access.

Although electronic medical records and a central database have made accurate and consistent patient medical information more readily available than with the traditional patient chart, there are many locations in healthcare facilities where terminals for accessing patient data are not available. As patient care becomes decentralized and more patients require anesthesia outside of the operating suites, routing a network-based system to all these locations can be expensive and time consuming. We designed a system whereby essential patient data of interest to anesthesiologists is stored on an electronic memory device the size of a watch battery attached to the patient's wristband. Accessing and editing the data is done via a hand-held computer. This system provides secure patient data storage and management at the "point of care." At the conclusion of the patient's anesthesia-related care, the data is downloaded to a relational database for use in outcome analysis, billing, and quality assurance. After collecting preoperative evaluations, intraoperative data, and postoperative data on 560 patients anesthetized for surgery or other procedures, we find this system to be a reliable, low-cost, medical information management system, with possible application to other medical specialties.

Patients with malignant osteopetrosis are at high risk of anesthetic morbidity and mortality.

UNLABELLED: The anesthetic literature contains no focused discussion of the perioperative management and risks of children with malignant autosomal recessive osteopetrosis (osteopetrosis). We retrospectively analyzed the perioperative morbidity and mortality rates encountered in the anesthetic management of children with osteopetrosis. We compared the perioperative mortality rate for this patient population with that for other pediatric patients in our institution and that reported in the literature for children and other high-risk patients. We also investigated the inability to intubate the tracheas of children with osteopetrosis compared with other pediatric patients in our institution. Using Fisher's exact test, patients with osteopetrosis were found to have a higher likelihood of perioperative mortality compared with other children or all ASA physical status III, but not ASA physical status IV, patients (P < 0.05). Finally, we discovered that children with osteopetrosis were more likely to have tracheas that could not be intubated than other pediatric patients in our institution. We conclude that children with osteopetrosis are at risk of adverse respiratory events and mortality associated with these adverse events. IMPLICATIONS: Osteopetrosis is a rare disease that increases perioperative morbidity and mortality. By performing a retrospective chart review, we found that this increased perioperative morbidity and mortality is primarily related to airway and respiratory factors. Anesthetic management strategies should consider the factors that cause the high frequency of adverse airway events in this patient population.

The relationship between the stages of exercise adoption and other health behaviors.

PURPOSE: To examine the relationship between stage of exercise adoption and the practice of other health behaviors. DESIGN: Demographic, socioeconomic, and health behavior data were collected using a cross-sectional mail survey. Data were collected as part of a larger employee benefits research study. SETTING: Montana State University-Bozeman, Bozeman, Montana. SUBJECTS: University employees (n = 1269) comprised of 46% men with a mean age of 44 years. MEASURES: Demographic and socioeconomic data included age, sex, marital status, level of income and education, dependent status, and job classification. Stage of exercise adoption classifications were based on self-reported responses to four exercise statements. The health behaviors included in this study were cigarette and smokeless tobacco use, seat belt use, alcohol use, and use of stress management practices. Logistic regression analysis was used to determine if stage of exercise predicted the presence of each of the health behaviors while controlling for demographic, socioeconomic, and other health behavior variables. RESULTS: The survey response rate was 68%. Respondents in action exercise stage (p = .0367) were less likely to smoke cigarettes than respondents in precontemplation stage of exercise. Respondents in contemplation (p = .0419), preparation (p = .0060), action (p = .0432), and maintenance (p = .0006) were more likely to use seat belts than respondents in precontemplation. Respondents in maintenance (p = .0059) were more likely to use regular stress reduction techniques than respondents in precontemplation. CONCLUSIONS: Although longitudinal research is needed to determine any causal relationships, this research suggests that encouraging individuals to become more involved in exercise could indirectly influence other health behaviors. Hence, exercise could be a possible "gateway" behavior toward healthier lifestyle practices.

Do submerged aquatic plants influence their periphyton to enhance the growth and reproduction of invertebrate mutualists?

It has been suggested that submerged aquatic plants can influence the nutritional quality of the periphyton which grows on their surfaces, making it more nutritious for grazing invertebrates, particularly snails. In return, these grazers might preferentially feed on the periphyton and clear the plants of a potential competitor, with the plants and grazers both gaining from this mutualistic relationship. A highly replicated experiment was conducted, in which the nature of the plant (isoetid and elodeid types compared with similar-shaped inert substrata), the nutrient loading, and the influence of periphyton grazers (the bladder snail, Physa fontinalis) of similar size and history were controlled. Plant growth and survival significantly increased in the presence of the periphyton grazer. Whilst the presence of the grazers had the largest influence on periphyton abundance, nutrient availability and plant type also had effects. Plant type had little influence on the nutritional quality of the periphyton measured as carbohydrate, protein and C:N. Effects of treatment on snail growth, and the timing and extent of snail reproduction disappeared when they were compared with the quantity of periphyton available. There was no evidence of enhanced grazer success in the presence of the live plants compared with inert substrata. Although submerged plants affect the growth and reproduction of the grazers which feed on their surfaces, through differences in the amount of periphyton which grows there, we found no evidence that they manipulate the periphyton to encourage such grazers.

Postoperative nausea and vomiting: review and clinical approaches.

Postoperative nausea and vomiting (PNV) is a common disorder at the forefront of ambulatory care issues. New antiemetic drugs and improved anesthetic techniques have decreased the incidence of anesthesia-induced PNV. Patient characteristics and surgical factors are now largely responsible for postoperative emesis. Clinicians need to understand these factors to deal effectively with PNV as the use of ambulatory surgery increases. Physicians should consider both prophylactic drug intervention and direct treatment.

A proposal for a two-dose/single-sample in vivo/in vitro rat hepatocyte unscheduled DNA synthesis assay.

We have developed a two dose/single-sample protocol for the in vivo/in vitro rat hepatocyte unscheduled DNA synthesis (UDS) assay. In order to enhance the effectiveness of grain detection by image analysis we found minor technical modifications to be beneficial. These included the use of 3% acetic acid in ethanol (or 4% aqueous paraformaldehyde) for hepatocyte fixation and 0.5% aqueous eosin for staining. Also, there was no correlation between cell viability (measured using the trypan blue method) and UDS response and, therefore, we do not reject animals from data analysis unless hepatocyte viability falls below 50%. Furthermore, we suggest that cell attachment is a more reliable indicator of toxicity than of cell viability. Therefore, our range-finding test has been modified to incorporate an extra animal per group so that hepatocyte cultures can be evaluated. Comparisons of a two-dose/single-sample protocol with the currently accepted single-dose/multiple-sample protocol demonstrated that the former was an acceptable alternative, in that responses with standard positive controls are very similar with both protocols. Furthermore, the two-dose protocol has clear advantages in that it uses fewer animals, resources and time and has better statistical discriminatory power. As a move away from the use of arbitrary values for determining the performance and outcome of assays, we use criteria based on confidence limits placed on historical data ranges. Where necessary, statistical analyses of concurrent data is performed using rank transformation followed by parametric analysis of the ranks; this combines the generality of a non-parametric methodology with the power and versatility of parametric analyses.

Prevalence of antibodies to hepatitis C virus and other markers in Jamaica.

Three population groups, 1500 blood donors, 513 antenatal women representing a normal population group and 250 sicklers representing a multiply transfused group were studied to determine the prevalence of hepatitis C viral (HCV) infection in Jamaica. The relationship to liver enzyme levels, hepatitis B infection, syphilis and HIV infection was also investigated. Sera were screened by enzyme-linked immunoassay (EIA) for anti-HCV C100-3 and subsequently tested by a supplementary second generation recombinant immunoblot assay (RIBA). In the blood donors, the prevalence of anti-HCV was low, 0.3%-0.4%, the same level as that reported by several European countries. In the multiply transfused sicklers, the prevalence was more than seven times higher. No HCV infection was detected in the antenatal group. There was little correlation between HCV infection and surrogate markers alanine aminotransferase (ALT) and antibody to hepatitis B core antigen (anti-HBc) and no correlation with sexually transmitted diseases.

Postoperative analgesia after major shoulder surgery with interscalene brachial plexus blockade: etidocaine versus bupivacaine.

Postoperative pain is commonly treated with significant doses of narcotics, occasionally resulting in side effects including nausea, pruritus, and respiratory depression. One potential advantage of regional anesthesia is profound postoperative analgesia that reduces exposure to potent narcotics. To evaluate the efficacy of two long-acting local anesthetics, bupivacaine and etidocaine, in providing pain relief after major shoulder surgery, we randomized 20 patients to receive either bupivacaine or etidocaine for brachial plexus block as the primary anesthetic for shoulder surgery. Surgeons, patients, and the acute pain service were blinded as to drug selection. After the patient was sedated, an interscalene block was placed with the use of a nerve stimulator to facilitate proper needle placement. Forty milliliters of either 0.5% bupivacaine or 0.75% etidocaine containing 5 micrograms/mL epinephrine was injected into the brachial plexus sheath. An additional 8 mL of local anesthetic was administered for superficial cervical plexus blockade. Intraoperative sedation was accomplished with an intravenous infusion of methohexital as needed. After surgery, patients received a standard patient-controlled analgesia protocol providing incremental doses of morphine. The degree of postoperative analgesia resulting from residual local anesthetic effect was expressed as the time until first morphine requirement and the total dose of morphine required during the first 24 hours postoperatively. We found no statistically significant intergroup differences either in time of initial use of morphine or in the total dose of morphine required in the first 24 hours. Both etidocaine and bupivacaine provide prolonged analgesia after major shoulder surgery when injected into the brachial plexus. Bupivacaine, however, possesses significant cardiotoxicity and has a relatively delayed onset in peripheral neural blockade. Etidocaine is less cardiotoxic and also has a more rapid onset of effect. Thus etidocaine may be a preferable agent for interscalene block for major shoulder surgery.