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Biomedical subjects

C A Roberts

Publications and source records attributed to C A Roberts.

At least 73 records · Page 4Linked to original sources
PubMed1995

Clinical observations made in nonheat acclimated horses performing treadmill exercise in cool (20 degrees C/40%RH), hot, dry (30 degrees C/40%RH) or hot, humid (30 degrees C/80%RH) conditions.

Four horses (H, J, N and M) undertook a treadmill competition exercise test (CET), designed to simulate the physiological and metabolic stresses of the Speed and Endurance phase of a 3-day-event, under 3 different environmental conditions: 20 degrees C/40% relative humidity (RH) (cool, dry [CD]: 2 sessions); 30 degrees C/40%RH (hot, dry [HD]) and 30 degrees C/80%RH (hot, humid [HH]) (Marlin et al. 1995). A number of subjective clinical observations were made at designated time points throughout the exercise test and initial recovery period including buccal mucous membrane colouration, capillary refill time, neck and point of shoulder skin pinch recovery time, grade of abdominal sounds; anal sphincter tone as well as the presence or absence of fatigue and ataxia. The aim was to investigate their value in predicting performance in the final canter phase of the CET equivalent to the cross-country or Phase D of a field competition. In addition, the use of a more objective assessment, the cardiac recovery index (CRI), was investigated together with the heart rate, rectal temperature and respiratory frequency at the end of Phase C and at the 8 min point of the 10 Minute Box (8'X). The CRI was calculated according to the formula CRI = P2-P1 where P2 = the heart rate in beats/min at the 8 min point of the '10 Minute Box' (Phase X) of the CET. P1 = the heart rate (beats/min) at the 7 min point just before the horse was made to trot over a distance of 80 m at a speed of 3.7 m/s (at a 3 degrees incline) before returning to a walk. The study suggested that the subjective tests carried out at the 'End-C' and/or '8'X' time points were not useful in predicting subsequent performance in the final canter phase (Phase D) and neither were heart rate, rectal temperature or respiratory frequency. However, the only horse (Horse H) to complete the full CET under HH conditions was the only animal to show a decrease in respiratory frequency between the End-C and 8'X time points. All others showed an obvious increase. Under HH conditions, Horse H also had the lowest CRI. For 3 of the horses the highest CRI value was found under the HH conditions, for the fourth horse an equally high CRI value was found with one of the CD sessions. However, under the HH conditions, both P1 and P2 values were > 100. The study suggested that it could be beneficial if a suitably modified CRI test, as well as a procedure to monitor the change in respiratory frequency during the 10 Minute Box, were evaluated further on the treadmill and in the field with respect to their potential usefulness as additional aids to the assessment of a horse's suitability to proceed to Phase D.

Acclimatization↗
PubMed1995

Electrolyte and total protein changes in nonheat acclimated horses performing treadmill exercise in cool (20 degrees C/40%RH), hot, dry (30 degrees C/40%RH) or hot, humid (30 degrees C/80%RH) conditions.

Four horses (H, J, N and M) undertook a simulated competition exercise test (CET), designed to simulate physiological and metabolic stresses of the Speed and Endurance (S & E) test of a 3-day-event, under 3 different environmental conditions: 20 degrees C/40% relative humidity (RH) (cool, dry [CD] 2 sessions); 30 degrees C/40% RH (hot, dry [HD]) and 30 degrees C/80% RH (hot, humid [HH]) (Marlin et al. 1995a). Venous blood samples for electrolyte and total protein (TP) determinations were collected from indwelling catheters at predetermined time points throughout each CET and initial 30 min recovery period. Venous blood samples were collected by jugular venepuncture at 2 h and 24 h after the end of the final 8 min canter (Phase D). The effects of exercise, environmental condition and horse on venous TP, sodium (Na+), potassium (K+), chloride (Cl-), calcium (Ca2+), magnesium (Mg2+) and phosphate (PO4(3-)) plasma concentrations were investigated. In addition, the effect of environmental condition on estimated cation loss was evaluated. All horses completed the full CET under the CD and HD conditions, but only one horse completed the full 8 min of the final canter Phase D under HH conditions. Exercise had a significant (P < 0.05) effect on all parameters similar to those reported previously in field competitions. There was a significant (P < 0.05) interaction between time and horse for TP, Na+ and Cl-. Overall, the environmental condition had a significant (P < 0.05) effect on all parameters, but the differences were not considered to be of any physiological relevance, other than for Cl- and TP. There was a significant (P < 0.05) interaction between time and environmental condition for Cl- and TP only. During much of the CET and recovery period, mean Cl- values were higher with the first CD session than the second CD session or under the HH or HD conditions. For TP after 2 min of Phase D and during the initial recovery period, concentrations were higher under the HH conditions and returned to the Pre- values less quickly. There were marked individual variations in the estimated cation losses and no consistent effect of environmental condition was found. Although estimated fluid loss was similar following both HD and HH sessions, restoration of bodyweight was slower following the CET studies under HH conditions.

Acclimatization↗
PubMed1993

Stride length and respiratory tidal volume in exercising thoroughbred horses.

The purpose of this study was to test the hypothesis that locomotor-respiratory coupling in horses may provide a basis for the appropriate matching of lung ventilation to running speed and metabolic power. This was achieved by determining the effect on respiratory frequency and tidal volume in thoroughbred horses of changing running speed while maintaining a constant metabolic demand by also varying the incline of the treadmill. This procedure was performed at three different speeds at two different levels of metabolic rate. It appears that, in response to metabolic demands which are not directly related to speed, horses can control tidal volume independently of stride length but they do not vary respiratory frequency independently of stride frequency. When running at 0 degrees incline, however, they probably do not operate an elevated tidal volume, because of the increased energetic costs such an elevated tidal volume would incur.

Animals↗
PubMed1993

Streptococci and Pasteurella spp. associated with disease of the equine lower respiratory tract.

The likelihood of finding evidence of inflammation in 551 tracheal washes collected endoscopically from 278 Thoroughbred racehorses increased with the number of bacterial colony forming units (cfu) per ml of wash (P < 0.001). The aerobic bacteria Streptococcus zooepidemicus, Pasteurella/Actinobacillus-like species and Streptococcus pneumoniae were significantly associated with lower airway inflammation whereas coagulase-negative Staphylococcus spp., alpha-haemolytic Streptococcus spp., Acinetobacter spp., Bacillus spp., Escherichia coli, Pseudomonas aeruginosa, non-haemolytic Streptococcus spp. and Enterobacteriaceae were not; Bordetella bronchiseptica was not isolated. Lower airway inflammation was particularly associated with bacteria in horses < or = 3 years of age. S. zooepidemicus, S. pneumoniae and Pasteurella/Actinobacillus-like species were isolated from 167 of 551 washes, either alone or in combination.

Animals↗
PubMed1993

Respiratory and cardiovascular adjustments during exercise of increasing intensity and during recovery in thoroughbred racehorses.

A new design of flowmeter is described and used in a comprehensive study of the respiratory and cardiovascular adjustments that occur during a standardised exercise test in Thoroughbred horses. The flowmeter system and associated lightweight, fibreglass mask (total mass, 0.7 kg) have a maximum dead space of 500 ml and negligible resistance to airflow. They have no systematic effect on blood gases and, together with a rapidly responding mass spectrometer, enable an accurate computation of gas exchange to be performed together with breath-by-breath determination of other respiratory variables. At the highest level of exercise (12 ms-1 on a 3 degrees incline), the rate of oxygen uptake (VO2) and carbon dioxide production (VCO2) increased to 29.4 times and 36.8 times their resting values, respectively. Respiratory minute volume (VE) increased to 27.0 times its resting value, with respiratory frequency (fR) making the major contribution at the walk and trot. However, with increasing cantering speeds, fR changed little as it was locked in a 1:1 fashion to stride frequency, and tidal volume (VT) then made the major contribution to the increase in VE. The ratio of ventilatory dead space (VD) to VT in resting horses was lower than that previously reported in the literature and this could be the result of the different respiratory recording systems that were used. There was a close relationship between VT and stride length at increasing cantering speeds. Despite the fact that alveolar ventilation (VA) was well matched to VO2, there was a significant reduction in arterial PO2 (PaO2) when the horses cantered at 8 ms-1 and this eventually fell to 34% below the resting value. The present data tend to support the idea that VA/Vb (where Vb is cardiac output) inequalities are important in causing this hypoxaemia. However, the reduction in PaO2 was more than compensated for by an increase in haemoglobin concentration, [Hb], so the concentration of oxygen in the arterial blood (CaO2) was significantly above the resting value at all levels of exercise. Both lactate concentration and PaCO2 increased during exercise, causing substantial reductions in pH of both arterial and mixed venous blood. This would have inevitably shifted the oxygen equilibrium curve of the Hb to the right, desaturating the arterial blood and thus exacerbating the effect of the hypoxaemia, as would the almost 4 degrees C rise in blood temperature. The tight respiratory/locomotor linkage might prevent the acidosis and hyperthermia having the stimulatory effects on VE that they have in humans at high work loads.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Pressure erosion of the femoral trochlea, patella baja, and altered patellar surfaces.

As knee flexion increases, so do tendofemoral and patellofemoral compression forces. Three cases of long-standing uncorrected flexion contractures of the knees are presented that resulted in marked erosion of the femoral trochlea, patella baja, and remodeled patellar articular surfaces likely reflecting increased angles of flexion. It is probable that the deep femoral grooves are the result of adaptation under high-level persistent contact loads from the quadriceps tendon. These examples expand our knowledge of bone remodeling and offer information of potential use in studying ancient skeletal samples.

Adult↗
PubMed1990

Use of protrusive splint therapy in anterior disk displacement of the temporomandibular joint: a 1- to 3-year follow-up.

Sixty-eight patients, who were determined clinically (by the presence of audible and palpable-joint sounds) and arthrographically to have meniscus displacement with reduction, had protrusive splints constructed, and the results were evaluated for a minimum of 1 year to a maximum of 3 years. Eighteen additional patients, arthrographically determined to have meniscus displacement with reduction, served as a nontreatment group for comparison. Odds ratios were calculated to compare the proportions of subjects who experienced follow-up symptoms on the two regimens. Results indicated that with splint therapy there was a statistically significant reduction of the intensity of jaw joint pain, temporal headache, ear pain, and pain in front of the ear, and there was a decrease in the probability of a closed lock condition developing. Splint therapy is less likely to reduce frontal headache, neck pain, and clenching of teeth.

Adult↗
PubMed1990

Developmental patterns of plasma insulin-like growth factor-1 concentrations in sheep.

A study was undertaken to examine the ontogeny of circulating insulin-like growth factor-1 (IGF-1) concentrations in sheep. The trial was a balanced 2 x 2 factorial design incorporating the effects of sex and rearing rank with a total of 48 animals. Blood sampling was initiated four weeks post-weaning (about 3 months of age) and continued every 2 weeks for 6 months and then every 4 weeks for 7 months. Fecal egg counts and plasma concentrations of non-esterified fatty acids (NEFA) were also determined. IGF-1 concentration was positively related to live weight throughout the trial, even when adjusted to common sex and rearing rank. Sex of lamb had a significant effect on plasma IGF-1 concentrations with concentrations in males being greater than those in females. Puberty in females, as determined by date of first estrus, was associated with an increase in plasma IGF-1 concentrations. Although puberty in males was not measured, a surge in plasma IGF-1 concentrations around the approximate time of puberty in males resulted in a marked divergence between the sexes which remained throughout the study. Rearing rank did not influence plasma IGF-1 concentrations beyond 7 months of age. Plasma IGF-1 concentrations tended to be negatively associated with plasma NEFA concentrations and fecal egg counts but relationships were only occasionally significant. IGF-1 levels were highly repeatable, concentrations at the first sample being significantly correlated with those at all subsequent samples. Implications of these results in relation to potential use of plasma IGF-1 concentration as a genetic marker for productivity are discussed.

Animals↗
PubMed1990

Bicarbonate loading in the thoroughbred: dose, method of administration and acid-base changes.

Two studies were undertaken in an attempt to investigate the optimal dose, route and time course required to 'bicarbonate load' the Thoroughbred. During the first study a test solution of sodium bicarbonate (NaHCO3) and a control solution of water were administered via a nasogastric tube to six horses. Blood acid-base status was determined immediately prior to and for 24 h following intubation. During the second study a standardised feed was given to four horses, with and without NaHCO3 supplementation. This was followed by a further trial involving the addition of glucose and NaHCO3 to a standardised feed. During Study 1, plasma pH peaked 8 h after NaHCO3 intubation (7.433 +/- 0.020) and levels were still elevated above control values 12 h post intubation. Although there was a trend for blood PCO2 to be elevated above control values at all times after NaHCO3 administration, values were only significantly different at 4 and 5 h post intubation. The patterns of change in plasma HCO3- and blood base-excess after NaHCO3 administration were similar. Values peaked between 3 and 6 h post intubation and were still above control values 12 h post intubation. In Study 2 attempts to alter acid-base status by presenting NaHCO3 mixed with feed were unsuccessful because horses failed to consume the total mix, despite attempts to mask the unpalatable nature of the feed by adding glucose. The results suggest that future studies investigating the influence of NaHCO3 on exercise performance and metabolism should possibly involve administration of NaHCO3 in a greater quantity than is administered conventionally (0.3 g/kg). More meaningful results may be obtained if NaHCO3 is administered as a solution, via a nasogastric tube, at least 3 h prior to exercise.

Acid-Base Equilibrium↗
PubMed1990

Nursing research and the care of chronically ill and disabled children.

This is a review of a group of studies comprising the nursing research literature concerning the care of chronically ill and disabled children and their families. Six purposively selected nursing journals were examined for articles published over an 8-year period (1980 to 1987), in order to investigate the scientific potential of this research in building a knowledge base for practice. The descriptive studies provide many areas for consideration in nursing assessments, particularly psychosocial aspects. However, the relatively few experimental studies of nursing interventions provide only fragments of research findings for direct application into practice. It was concluded that this body of research is in its early stages of development. Current gaps and possible future directions for nursing research are wide-ranging.

Child↗
PubMed1989

Viewpoint: development of mental health services and psychiatry in Canada: lessons from the past: problems of the present; and the future.

The history of mental health services in Canada has been characterized by great frustration for those dedicated to the development of programs to meet the needs of the mentally ill. Acceptance of these services by the public at large has been limited and characterized by suspicion and lack of trust. In recent decades these two trends have contributed to the present situation in which it is difficult to recruit competent, well-motivated clinical staff for our more isolated mental hospitals and there is increasing emphasis on legalistic aspects of individual civil rights, compulsory treatment and related factors with little attention to the patient's entitlement to and need for adequate treatment. It is hypothesized that more understanding and progress may come from an insightful review of the historical development of Canadian Mental Health Services and the goals of organized Psychiatry in Canada than will result from developing a defensive and confrontational attitude towards current events in the field.

Canada↗
PubMed1988

In vivo depression of reserve albumin binding capacity by cadmium: a preliminary evaluation.

The effect of cadmium upon the depression of reserve albumin binding capacity (%RABC) was investigated in male, New Zealand white rabbits at daily dosages of 0.65 mg and 0.90 mg Cd/kg body weight. Correlations of % RABC to the duration of exposure were strongest at the higher dosage. After 30-35 days exposure, the decline in % RABC was partially reversed. Levels of total protein in urine increased sharply within a few days after the % RABC had been reduced by cadmium to their lowest values.

Animals↗
PubMed1988

Correlation of clinical parameters to the arthrographic depiction of temporomandibular joint internal derangements.

This prospective clinical investigation of 188 patients with signs and symptoms of temporomandibular joint (TMJ) pain and dysfunction examines the correlation between clinical signs and symptoms versus the arthrographic characteristics of intracapsular disease related to displacement of the meniscus. An attempt has been made to establish which specific clinical signs and symptoms, as determined by arthrography, best predict the condition of the joint. Our findings suggest that most of the clinical signs and symptoms are not sufficiently reliable in themselves to permit prediction of the condition of the meniscus. Those clinical parameters that did show a strong correlation were tested in combinations using stepwise discriminant analysis to evaluate clinical tendencies. Thus, patients with normal meniscal position and function were often noted to have normal mandibular ranges of movement, no joint noises on opening and closing of the jaw, and no tomographic evidence of degenerative joint disease. Subjects with meniscal displacement with reduction were often found to have joint clicking, deviation of the jaw upon opening, and an absence of degenerative joint disease by multidirectional tomography. Patients who had meniscal displacement without reduction were often found to have limitation in jaw movement, crepitation on opening and closing of the jaw, and associated degenerative changes on multidirectional tomograms. If specific treatment plans are to be tailored for different stages of TMJ internal derangements, clinical findings alone or clinical findings in conjunction with plain radiographs of the TMJ are not consistently accurate.

Adult↗
PubMed1987

Comparison of arthrographic findings of the temporomandibular joint with palpation of the muscles of mastication.

Two hundred five patients were examined for temporomandibular joint pain and dysfunction and specifically for tenderness to muscle palpation. Arthrograms were performed on 222 joints (188 unilateral and 17 bilateral). Significant findings were ascertained for the middle portion of the temporal muscle in "normal" patients versus "with and without meniscus reduction" patients. The superficial masseter muscle was more tender in "normal" patients and in "reducing meniscus" patients than in "without meniscus reduction" patients. The medial pterygoid muscle was more tender in "normal" patients and in "without meniscus reduction" patients than in "reducing meniscus" patients. Though there are some significant findings with respect to muscle palpation, by itself muscle palpation is not a specific indicator of temporomandibular joint internal derangement.

Arthrography↗