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Biomedical subjects

R J Rose

Publications and source records attributed to R J Rose.

At least 109 records · Page 6Linked to original sources
PubMed1994

Significance for exercise capacity of some electrocardiographic findings in racehorses.

Various cardiorespiratory and metabolic indices were assessed during treadmill exercise in Thoroughbred and Standardbred racehorses with T wave changes in 4 or more leads on the electrocardiogram or second-degree atrio-ventricular (AV) block, and in horses that had no abnormalities on clinical examination, resting electrocardiography or upper respiratory tract endoscopy. No significant differences in heart rate, plasma lactate concentration, arterial blood gases, oxygen uptake, run time, peak velocity, or blood and red cell volumes were found between normal horses and horses with T wave changes or second-degree AV block. These results indicate that some electrocardiographic findings that are considered by some clinicians to indicate cardiac dysfunction, may have little effect on exercise capacity.

Animals↗
PubMed1994

Cardiorespiratory and metabolic responses to exercise in horses with various abnormalities of the upper respiratory tract.

A standardised incremental exercise test was performed by 9 racehorses with idiopathic laryngeal hemiplegia (ILH), 1 horse with maxillary sinus cysts, 1 horse with epiglottic entrapment, 1 horse with a lesion on the vocal folds, and 1 horse with pharyngitis. Two of the horses with ILH were retested after laryngoplasty and ventriculectomy. The findings were compared with those from 20 normal racehorses. Heart rate, plasma lactate concentration, arterial blood gases, stride frequency, oxygen uptake (VO2) and carbon dioxide production were assessed during treadmill exercise on a +10% slope. The group of horses with ILH had significantly (P < 0.01) lower peak VO2 values (136 +/- 5 ml/kg/min) than did the normal group (154 +/- 3 ml/klg/min). These values represent mean +/- sem. Horses with ILH also had significantly higher (P < 0.05) arterial carbon dioxide tensions (PaCO2) at 10 m/s and lower speeds at a heart rate of 200 bpm (V200) than the normal group. The horse with maxillary sinus cysts had higher PaCO2 tension at 10 m/s than normal, and abnormal values for several cardiorespiratory and metabolic indices. Horses with vocal fold lesions, aryepiglottic entrapment and pharyngitis had arterial blood gas and cardiorespiratory indices that were similar to those of normal horses. One horse which underwent corrective surgery for ILH showed improvements in arterial blood gases and cardiorespiratory indices during exercise, while the other horse had values which were the same as, or worse than, values before surgery. We conclude that the measurement of arterial blood gases and cardiorespiratory indices during treadmill exercise is useful in determining the effect on exercise capacity of various upper airway abnormalities in racehorses.

Animals↗
PubMed1993

Effect of constant load training on skeletal muscle histochemistry of thoroughbred horses.

Skeletal muscle adaptations to training of differing intensities were examined in 10 thoroughbred horses that underwent six weeks of treadmill training followed by six weeks of detraining. The horses were randomly assigned to either a slow group exercised at 40 per cent maximum oxygen uptake (VO2max) or a fast group at 80 per cent VO2max. Resting muscle biopsies were taken before training, after six weeks of training and after six weeks of detraining, from m gluteus medius and m biceps femoris. Muscle was analysed histochemically for fibre type composition (myosin ATPase) and capillary supply (PAS amylase). Cross sectional area and lesser fibre diameter were measured by planimetry and image analysis. No alterations were found in the proportions of different muscle fibre types during training or detraining. Capillary density increased by 54 per cent in m biceps femoris of the fast group during training and decreased to the pretraining level following detraining. Few changes in fibre size occurred as a result of training and detraining. It was not possible to draw conclusions as to the effects of detraining because of the small number of training induced changes. The results suggest that for major adaptations in skeletal muscle, an increasing exercise intensity throughout training may be more significant than the degree of exercise load, when exercise intensity is submaximal.

Adaptation, Physiological↗
PubMed1993

Equine bronchoalveolar lavage cytology: survey of thoroughbred racehorses in training.

Sixty-two Thoroughbred horses aged between 1 and 7 years in training in Sydney had bronchoalveolar lavage (BAL) samples collected for cytological examination. All horses, except the yearlings and those with a cough, had raced at the time of the examination and the trainers reported satisfactory performance. Free erythrocytes were found in 73% of samples and haemosiderophages in 90% of the samples, indicating immediate or past occurrences of exercise-induced pulmonary haemorrhage (EIPH). Bronchoalveolar fluid from the yearlings contained significantly less (P < 0.05) erythrocytes and haemosiderophages than samples from horses in other age groups. In the older horses, there was also more haemosiderin within the macrophages. No differences in BAL cytology could be attributed to gender, and there was no relationship between BAL cytology and racing performance. The main cytological findings were (mean +/- sd): total nucleated cells--832 +/- 578/microL with the main cell types being: macrophages--59 +/- 10% (haemosiderophages--20 +/- 24%); neutrophils--9 +/- 6%; lymphocytes--31 +/- 9%. The erythrocyte count was 10.3 +/- 17.7% of the total cell count. Horses with chronic coughing had a higher proportion of macrophages and a lower proportion of lymphocytes in the leucocytes obtained from BAL. There was a higher occurrence of EIPH detected in BAL findings than that previously reported when endoscopic examination has been used to diagnose EIPH. The occurrence and severity of EIPH as indicated by the BAL findings was found to be related to exercise intensity. The cytological findings were similar to those reported in horses in the northern hemisphere.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Nutrient intake of horses in thoroughbred and standardbred stables.

Twenty-five Thoroughbred (TB) and 25 Standardbred (SB) stables were visited to determine their feeding practices. The ingredients of the main feed of the day for a mature gelding of average size in full training were weighted at each stable. Nutrient content of diets was calculated using published data for the individual ingredients. Results are expressed as mean +/- sd. The estimated body weight of TB horses was 493 +/- 34 kg and 437 +/- 32 kg for SB horses. There was considerable variation in diet composition and nutrient intake between stables. The TB trainers fed 11.0 +/- 2.4 kg and SB trainers 11.8 +/- 2.5 kg per day. The concentrate component of the diet weighed 7.8 +/- 1.6 and 7.7 +/- 2.3 kg for TB and SB stables, respectively, and the roughage component for TB horses 3.3 +/- 1.4 and SB horses 4.1 +/- 1.4 kg per day. The digestible energy intake of horses at TB stables was 129 +/- 29 MJ per day and at SB stables 132 +/- 31 MJ per day. Crude protein intake of TB horses was 1452 +/- 363 g and SB horses 1442 +/- 338 g per day. There were differences in some feeding practices at TB and SB stables. Standardbred trainers fed more roughage than TB trainers. Standardbred trainers fed chaffed lucerne (alfalfa) and cereal hays as the major roughage, whereas TB trainers fed more hay. The major hay type fed by TB trainers was lucerne, whereas many SB trainers preferred clover hay. Both trainers fed oats as the major grain, but TB trainers fed slightly more maize (corn) than SB trainers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1993

Nutrient utilisation by the hindlimb of thoroughbred horses at rest.

Nutrient uptake by the hindlimb was investigated utilising the arteriovenous difference technique in 5 Thoroughbred horses fed to maintenance a diet of 100% roughage or 52% oat grain and 48% roughage. Arterial blood was obtained from a catheter inserted into the carotid artery while venous blood was simultaneously collected from a catheter placed into the iliac vein via the medial saphenous vein. The arteriovenous difference for glucose was significant and represented a mean extraction of 10 +/- 1% with no effect of diet. If fully oxidised, glucose uptake (corrected for lactate and pyruvate arteriovenous difference) was sufficient to account for 78 +/- 13% or 107 +/- 15% of the oxygen consumed by the hindlimb in horses fed a roughage or 52% oat grain diet respectively. Acetate was also a major metabolite of the hindlimb, showing a 39 +/- 5% extraction with no effect of diet. However, the 52% oat grain diet did induce a significant decline in the concentration of acetate in arterial blood. The potential contribution to oxidation in the hindlimb was significantly reduced from 32 +/- 4% in horses fed roughage to 21 +/- 3% when fed 52% oat grain. D-3-Hydroxybutyrate uptake could account for 9 +/- 1% of the oxidation by the hindlimb with no effect of diet. The technique for measuring nutrient uptake across the hindlimb using the arteriovenous difference is relatively simple and would be valuable in investigating fuel use by muscle during exercise.

3-Hydroxybutyric Acid↗
PubMed1993

Effects of sodium bicarbonate on cardiorespiratory measurements and exercise capacity in thoroughbred horses.

We examined the effects of sodium bicarbonate in 6 Thoroughbred horses during submaximal and maximal treadmill exercise. Cardiorespiratory function was assessed together with the effect on exercise capacity by determining the run time to fatigue at maximal intensities. To discriminate between sodium bicarbonate's alkalinising effects and the fluid shifts that could result from the high osmotic load, we administered an equimolar solution of sodium chloride as a control. The horses were given sodium bicarbonate (1 g/kg bwt) or an equivalent number of moles of sodium chloride by nasogastric tube. Arterial blood samples were collected before exercise and 5 h after treatment, resulting in mean standard bicarbonate values of 39.6 mmol/l in horses treated with sodium bicarbonate compared with 24.2 mmol/l in horses that received saline. The horses were exercised on a treadmill at 40, 60 and 80% of their VO2max for 4, 2 and 2 mins respectively. The horses were walked for 3 mins and accelerated rapidly to a speed approximately equivalent to 110% VO2max and run until fatigued. The horses ran for 170 +/- 20 secs (mean +/- sem) after administration of sodium bicarbonate compared with 128 +/- 13 secs after receiving sodium chloride (P < 0.02). At rest and throughout submaximal and maximal exercise, the bicarbonate-treated horses had significantly lower arterial oxygen tensions and higher arterial carbon dioxide tensions. There were no differences in cardiac output, heart rate, oxygen uptake or carbon dioxide production between the saline and bicarbonate treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

The effect of roughage source on exercise performance and metabolism in thoroughbred horses.

The effects of roughage source on metabolism and exercise capacity were investigated using 6, previously conditioned, mature thoroughbred horses in a cross-over experiment. The horses were assigned to either non-alfalfa or alfalfa roughage diets which were isocaloric. The diets were fed for 2 weeks, after which the horses were exercise tested and then fed the alternate diet. Horses were exercised on a high-speed treadmill using a rapid incremental test. Arterial blood samples were collected for blood gas analysis and acid base measurements and venous blood samples for lactate and red blood cell potassium analysis. Mixed expired gas samples were collected for measurement of oxygen uptake, carbon dioxide production and respiratory exchange ratio. Heart rate was measured by telemetry ECG and respiratory frequency by observation. When the 2 diets were compared there were no significant differences in treadmill exercise capacity nor in any of the metabolic or cardiorespiratory measurements made before, during or after the exercise period. We concluded that roughage source has no effect on cardiorespiratory and metabolic function during or after exercise, and does not affect endurance performance during a treadmill exercise test.

Animal Nutritional Physiological Phenomena↗
PubMed1992

The spinach chloroplast chromosome is bound to the thylakoid membrane in the region of the inverted repeat.

By using a novel fractionation procedure we show that the chloroplast chromosome is specifically bound to the spinach thylakoid in the region of the inverted repeat, near the 16S and 23S rRNA genes. Central to the method is the use of restriction endonucleases, followed by ethylenediaminetetraacetic acid (EDTA) treatment to loosen or uncoil the nucleoid by the removal of specific proteins. The data we present provide a basis for understanding the molecular mechanism of membrane-bound cpDNA function.

Chloroplasts↗