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Biomedical subjects

A Littlejohn

Publications and source records attributed to A Littlejohn.

At least 37 records · Page 2Linked to original sources
PubMed1977

Exercise studies in horses: 1. A simple telemetry system for recording excercise ECGs in horses.

A robust low cost portable radiotelemetry system is described for the horse and its method of operation and advantages briefly discussed. The equipment consisted of 2 electrodes forming a bipolar lead, a transmitter, a receiver and a writing device. The sitting, application and immobilising of the electrodes was a most important factor in obtaining good quality recordings. ECGs were recorded at all paces and also while jumping and the results proved satisfactory.

Animals↗
PubMed1977

Exercise studies in horses: 2. The cardiac response to exercise in normal horses and in horses with chronic obstructive pulmonary disease.

The relationship of velocity (v) to heart rate (HR)and of kinetic energy (KE) to heart rate, were investigated in 6 normal horses and in 6 horses with chronic obstructive pulmonary, disease (COPD). Radiotelemetry was used to determine the heart rate while subjects were ridden on a 400m track. Velocity was measured by stop-watch between 2 markers 50 m apart at the end of the track. Kinetic energy was calculated from the formula KE =1/2 Mv2, where M = mass of horse, rider, saddle and bridle (KG) and V = velocity (metres per second). In all subjects, the relationship of velocity to heart rate was a linear one at each individual pace (i.e. walk, trot and gallop). There were however significant differences between the v/HR regression curves of each pace. These differences indicated that the increase in velocity per unit increase in heart rate was greater at the trot than at the walk, and greater at the gallop than at the trot. When data for all paces were combined, the relationship log v/log HR was a linear one. The above findings were also true of the relationship of kinetic energy to the heart rate. In horses, which reached maximal heart rate at a relatively low velocity, the v/HR curve became asymptotic. At comparable submaximal velocities, the heart rate of COPD subjects was approximately 20 beats per minute higher than that of normal subjects. This was also true when the term "kinetic energy per units mass" was substituted for velocity.

Animals↗
PubMed1975

Aspects of respiration in anaesthetized newborn foals.

The arterial oxygen tension (PaO2) in clinically normal newborn foals at 1300 m above sea-level is considerably lower (less than 60 mmHg) than in similarly aged foals at lower altitudes. This figure is further reduced to less than 50 mmHg without adverse effect in newborn foals at 1300 m maintained under pentobarbitone anaesthesia for prolonged periods. Measurement of O2 dissociation curves indicates that haemoglobin becomes saturated at a lower blood O2 tension in newborn foals than adult horses.

Altitude↗