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Biomedical subjects

C Johnston

Publications and source records attributed to C Johnston.

At least 91 records · Page 5Linked to original sources
PubMed1999

The kinematics of loading and fatigue in the standardbred trotter.

The Standardbred trotter must pull a considerable load when racing and, consequently, draught loading is a common method of training in the Standardbred and the effects of loading and fatigue due to loading on the locomotor pattern was the purpose of this investigation. Four mature healthy Standardbred horses trotted with and without a horizontal-pulling loading of 34 kg until the horses were no longer willing to keep pace with the treadmill despite encouragement. Heart rate was monitored every min using a bipolar electrocardiogram. The kinematics for 5 consecutive strides were filmed. Horses exercised on the treadmill for 7-10 mins. The mean heart rate was 206 beats/min at the end of the exercise. Due to draught loading, the horses reduced significantly the time of the stance phase in both the fore- and hindlimb. Three of the 4 horses reduced their stride lengths as the result of increased loading. The general movement pattern of the horses remained similar. More dramatic changes in the movement pattern were observed because of fatigue. The limbs of the horse were significantly more compressed as the result of greater joint excursion during the stance phase. Furthermore, the length of stride was significantly increased as the result of fatigue. The results show that both loading and fatigue change the locomotor pattern of the Standardbred trotter. Although the horizontal loading was considerable, the horse maintained similar joint movement with increases in stride frequency. During fatigue the horse seems to be unable to maintain stride frequency, probably due to a compromised power capacity of the muscles. The increase in joint excursion due to fatigue may have an important influence on certain types of injury to the locomotor system of the racehorse.

Animals↗
PubMed1999

Nerve block and intra-articular anaesthesia of the forelimb in the sound horse.

Nerve blocks and intra-articular anaesthesia are used extensively as routine methods in lameness evaluation. The method is based on the assumption that the technique itself does not change the movement pattern. The aim of this study was to carry out a quantitative kinematic study to confirm or reject the hypothesis that high palmar digital nerve block (HPDN) and intra-articular fetlock joint anaesthesia (IAF) influence significantly the movement pattern of the horse. Seven Standardbred horses trotting at 4.5 m/s were recorded at 240 Hz on a treadmill before and after anaesthesia by use of a ProReflex video system. Time variables, segment and joint angles were calculated. The high palmar digital nerve block (HPDN) resulted in a longer stance time and caused a greater fetlock joint angle range and greater maximal pastern joint angle. No systematic differences in time and angle variables were observed after intra-articular fetlock joint anaesthesia (IAF). In conclusion, HPDN but not IAF affects locomotor pattern in sound horses. Distal limb proprioception is important in normal movement, while fetlock intra-articular proprioception is apparently not. Interpretation of the effect of HPDN in lame individuals should incorporate more variables than maximal overextension of the fetlock joint.

Anesthesia↗
PubMed1999

Effects of flunixin on movement and performance of standardbred trotters on the track.

An often discussed and controversial issue is the effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on performance. The purpose of this study was to investigate the effect of the NSAID flunixin on the movement pattern and performance capacity of Standardbred trotters using a standardised track model. Five adult Standardbred horses in training trotted at 2 occasions with a 2 week interval on the same oval dirt track. Before each occasion the horses were either injected with flunixin meglumine (Finadyne) or normal saline solution i.m. 4 h before the performance test (double blind crossover study). The kinematics for 5 consecutive strides were filmed. There was no significant difference in maximal speed between the saline and flunixin treatment sessions. Significant changes in the movement pattern were observed as an effect of the flunixin treatment. The horses maintained the same stride duration while significantly decreasing stance time and increasing swing time in the forelimbs. The horses' range of limb angle decreased significantly. Heart rates were monitored and plasma lactate and flunixin concentrations were measured. No significant differences were found in heart rate and plasma lactate. The results indicate that flunixin had a significant effect on locomotor pattern while it did not effect metabolic response in these horses (considered to represent a normal race track population). The overall effect on performance in racing horses may therefore be related to the anti-inflammatory and analgesic properties of NSAIDs by masking pain and lameness.

Animals↗
PubMed1999

The effect of shoeing on kinetics and kinematics during the stance phase.

The increasing range of of horseshoes and hoofpads makes it important to be able to evaluate their influence on performance and stress in the locomotor apparatus. The aim of this study was to describe the changes in ground reaction forces and locomotion pattern during the stance phase due to the application of a standard iron shoe. Six Swedish Warmblood horses were evaluated kinetically and kinematically before and after they were shod with an 8 mm iron shoe. Data were used to calculate ground reaction forces in the vertical and craniocaudal directions, point of application of the force, hoof segment angle and hoof joint, pastern joint, fetlock, carpal and tarsal angles. Finally joint angular velocity and landing velocity of the hoof were calculated. During the initial phase of the stance or the concussion phase, the horses altered the conditions of the limb, as reflected by hoof-landing velocities. Concussion-dampening mechanisms of the distal limb subsequently were altered. In the nonshod condition, the coffin and fetlock joints rotated more rapidly in the forelimb and less rapidly in the hindlimb, while earlier proximal off-loading by the carpus and tarsus resulted in a decrease in initial horizontal loading at the hoof. It was concluded that horses accustomed to standard iron shoes demonstrate slight but significant differences in the movement and loading of the distal limb due to shoeing. Though the main differences were related to the concussion phase of the stance, even mid-stance loading and roll-over were altered. The study provides a basis for further investigation of the effect of various farriery techniques on the hoof and movement of the horse.

Animals↗
PubMed1999

Silica-induced chemokine expression in alveolar type II cells is mediated by TNF-alpha-induced oxidant stress.

We have shown previously that epithelial cells may contribute to the inflammatory response in the lung after exposure to crystalline silica through the production of and response to specific chemokines and cytokines. However, the exact cellular and molecular responses of epithelial cells to silica exposure remain unclear. We hypothesize that non-oxidant-mediated silica-cell interactions lead to the upregulation of tumor necrosis factor-alpha (TNF-alpha), whereby TNF-alpha-induced generation of reactive oxygen species (ROS) leads to the activation of the monocyte chemotactic protein (MCP)-1 and macrophage inflammatory protein (MIP)-2 genes. Using a murine alveolar type II cell line, murine lung epithelial (MLE)-15, we measured the early changes in TNF-alpha, MCP-1, and MIP-2 mRNA species after exposure of the cells to 18 micrograms/cm2 silica (cristobalite) in combination with various antioxidants. Total mRNA was isolated and assayed using an RNase protection assay after 6 h of particle exposure. We found that extracellular GSH could completely attenuate the cristobalite-induced expression of MCP-1 and MIP-2 mRNAs, whereas TNF-alpha mRNA levels were unaltered. We also found using the oxidant-sensitive dye 6-carboxy-2', 7'-dichlorodihydrofluorescein diacetate di(acetoxymethyl ester) that treatment of MLE-15 cells with cristobalite and TNF-alpha (1 ng/ml) resulted in ROS production. This ROS production could be inhibited with extracellular GSH treatment, and in the case of cristobalite-induced ROS, inhibition was also achieved with an anti-TNF-alpha antibody. The results support the hypothesis that TNF-alpha mediates cristobalite-induced MCP-1 and MIP-2 expression through the generation of ROS.

Animals↗
PubMed1999

Nietzsche and the dilemma of suffering.

In this paper, we attempt to view a long-held assumption in nursing as mistaken. That is, that patient suffering is something to be overcome. Utilizing Nietzsche's statements on Amor Fati, we carefully examine the cultural assumptions behind our denigration of suffering, look at specific nursing examples of this situation, and attempt the beginnings of a discourse on what it would take for nurses to overcome their own predetermined views of suffering in order to better help their patients "own" their own suffering.

Empathy↗
PubMed1998

Network helps hospitals develop own evidence-based medicine.

A Research Network Based in London, Ont., aims to improve hospital care by having hospitals share information. The research points out the ways some hospitals do things differently. Dr. William Sibbald, who heads the network, says that if hospitals overcome some of the variations between them, they may be "able to save money and become more efficient."

Critical Care↗
PubMed1998

Shape- and weight-based self-esteem and the eating disorders.

OBJECTIVES: To determine the psychometric properties of the Shape- and Weight-Based Self-Esteem (SAWBS) Inventory in women with eating disorders, and to compare SAWBS scores in women who have eating disorders with women from psychiatric and normal control groups. METHOD: Women with eating disorders (n = 48), women with other psychiatric disorders (n = 44), and undergraduate control women (n = 82) completed the SAWBS Inventory and measures of depression, self-esteem, and eating disorder symptomatology. Twenty women from the eating disorder group completed the SAWBS Inventory a second time 1 week later. RESULTS: Similar to previous work in undergraduate samples, SAWBS scores were stable over 1 week, and demonstrated concurrent and discriminant validity in women with eating disorders. In between-group comparisons, SAWBS scores were higher among women with eating disorders than in either control group, even after controlling for age, socioeconomic status, body mass index, and self-esteem. A differing relationship between depression and SAWBS emerged as a function of group; SAWBS scores differed significantly among depressed, but not nondepressed women from the three groups. CONCLUSION: The psychometric properties of the SAWBS Inventory were established in women with eating disorders. As expected, SAWBS scores were higher in women with eating disorders than in the control groups. Clinical implications of these findings are discussed.

Adult↗
PubMed1998

Collaboration in community based rehabilitation agencies.

One of the strategies which non-government organizations (NGOs) involved in Community Based Rehabilitation (CBR) use to develop their organizations and maximize their impact is through collaboration with other partners. A survey conducted by the International Centre for the Advancement of CBR identified collaboration styles, concerns, opportunities, and barriers among NGOs working in disability. Discussion focuses on differences between collaboration in industrialized and less developed countries; on resource dependency; and on structural characteristics of organizations that influence their interactions. The limited public concern for disability issues is viewed as a principal reason for the broad collaboration patterns which are seen in this field.

Ambulatory Care↗
PubMed1998

Silica-induced chemokine expression in alveolar type II cells is mediated by TNF-alpha.

Recent evidence has suggested that epithelial cells may contribute to the inflammatory response in the lung after exposure to crystalline silica through the production of and response to specific growth factors, chemokines, and cytokines. However, the exact cellular and molecular responses of epithelial cells to silica exposure remains unclear. Using a murine alveolar type II cell line [murine lung epithelial (MLE)-15 cell line], we measured the early changes in various cytokine and chemokine mRNA species after exposure of the cells to 4-35 microgram/cm2 of silica (cristobalite), interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and lipopolysaccharide (LPS) alone or in combination. Total mRNA was isolated and assayed with an RNase protection assay after 6 and 24 h of exposure. Cristobalite exposure alone led to an increase in monocyte chemotactic protein (MCP)-1, macrophage inflammatory protein (MIP)-2, and regulated on activation normal T cells expressed and secreted (RANTES) mRNAs. Treatment with IFN-gamma alone increased MCP-1 mRNA levels. Treatment with TNF-alpha or LPS alone led to an increase in MCP-1 and MIP-2 mRNA. The combination of cristobalite plus TNF-alpha led to an additive increase in MCP-1 and MIP-2, whereas cristobalite plus IFN-gamma or LPS had a synergistic effect. We also found with a TNF-alpha-neutralizing antibody that TNF-alpha plays a major role in mediating the type II cell chemokine response to cristobalite exposure. The results indicate that the cristobalite-induced chemokine response in the lung epithelium is mediated in part by TNF-alpha and can be enhanced by macrophage- and lymphocyte-derived inflammatory mediators in an additive and synergistic fashion.

Animals↗
PubMed1998

Assessing parent attributions for child behavior using open-ended questions.

Assessed parent attributions for child behavior using open-ended questions. Sixty-one parents of children with attention deficit hyperactivity disorder (ADHD) and 49 parents of nonproblem children participated. An open-ended, thought-listing question asked following child behavior indicated that parents spontaneously offer causal attributions for their children's behavior. Responses to a second open-ended question asking specifically for attributions for the child behavior indicated that both groups of parents attributed prosocial (PRO) child behaviors more than problem behaviors to internal, controllable, and stable causes or to the external situation and attributed problem behaviors most often to uncontrollable and unstable causes within the child or to factors within the parent. Compared with parents of nonproblem children, parents of children with ADHD were less likely to see themselves as the cause of child behavior and were more likely to mention medication. Analyses indicated that, although attributions elicited by rating scales were related to attributions provided in an open-ended format, each method provided unique information.

Adult↗
PubMed1998

Toppled television sets cause significant pediatric morbidity and mortality.

OBJECTIVE: To quantify pediatric injuries and deaths that result from toppled television sets. DESIGN: Retrospective analysis of incident files compiled by the US Consumer Product Safety Commission (CPSC) data systems and The Children's Hospital of Alabama (TCHA) inpatient medical records. SETTING: United States, January 1990-June 1997. TCHA, May 1995-October 1997. MAIN OUTCOME MEASURES: Morbidity or mortality as a result of a television set falling onto a child. RESULTS: Over the 7-year period from January 1990 to June 1997, 73 cases that involved falling television sets were reported to the CPSC, including 28 deaths. The mean age of all victims was 36 months (SD +/- 25.4 months). The mean age of those who died was 31 months (SD +/- 22 months). Females accounted for 42 incidents (58%) and 19 deaths (68%). The most common anatomic site of injury was the head, which accounted for 72% of cases investigated by CPSC personnel. Of the 14 deaths further investigated by the CPSC, head injury was responsible for 13, with a generalized crushing injury accounting for the other. Of the 45 cases in which data were available, dressers or stands were identified as the television support 76% of the time. The TCHA database yielded five additional cases, including one death, with demographics similar to the CPSC data. CONCLUSION: Serious injury and death can occur as a result of children toppling television sets from elevated locations in the home. The furniture on which a television set is situated is of fundamental importance. An estimate of overall risk to the population is impossible to determine from these data. In light of 73 reported cases with 28 deaths; however, injury prevention counseling and other strategies supporting in-home safety should include a secure and child-safe location for television sets. Attention should be paid to safer design and placement of this ubiquitous product. television, wounds and injuries, accidents, human, infants, children.

Accidental Falls↗