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Biomedical subjects

A Littlejohn

Publications and source records attributed to A Littlejohn.

At least 19 recordsLinked to original sources
PubMed1994

Crystal structure of human chorionic gonadotropin.

The three-dimensional structure of human chorionic gonadotropin shows that each of its two different subunits has a similar topology, with three disulphide bonds forming a cystine knot. This same folding motif is found in some protein growth factors. The heterodimer is stabilized by a segment of the beta-subunit which wraps around the alpha-subunit and is covalently linked like a seat belt by the disulphide Cys 26-Cys 110. This extraordinary feature appears to be essential not only for the association of these heterodimers but also for receptor binding by the glycoprotein hormones.

Amino Acid Sequence↗
PubMed1988

Circulatory, respiratory and metabolic responses in Thoroughbred horses during the first 400 meters of exercise.

These studies investigated circulatory, respiratory and metabolic responses in four Thoroughbred geldings during the first 400 metres of galloping (mean speed 14.4 +/- 0.38 m.s-1), cantering (mean speed 10.0 +/- 0.61 m.s-1) and walking (mean speed 1.58 +/- 0.05 m.s-1) from a standing start. A radio-controlled device which collected blood samples anaerobically during each 100 m section of the exercise track allowed analyses of changes in and functional relationships of the variables measured. During the 400 m gallop, the mean heart rate (HR) increased from 125 to 201 beats.min-1 and the haematocrit (Hct) from 0.513 to 0.589 l/l-1. The haemoglobin [Hb], lactate [LA] and potassium [K+] concentrations increased significantly, while the pH and the partial pressure of oxygen (PaO2) decreased significantly. The arterial partial pressure of carbon dioxide (PaCO2) and the plasma bicarbonate concentration did not change significantly. There were significant correlations between HR and Hct, HR and [Hb], HR and PaO2, HR and pH, HR and PvCO2, HR and [LA], HR and [K+], pH and [K+], Hct and PaO2, [Hb] and PaO2, PaCO2 and PaO2, [LA] and PaO2, pH and PaO2, [K+] and PaO2, stride frequency and PaO2. With the exception of the PvCO2 which increased significantly, changes in venous blood during the gallop were in the same direction as those of arterial blood. Thirty seconds before the start of the gallop, both HR and [Hb] were significantly higher than at rest, providing an approximate three-fold increase in oxygen delivery compared to that of the resting state.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

A comparison of systemic cefuroxime and cefuroxime loaded bone cement in the prevention of early infection after total joint replacement.

A controlled prospective randomised trial of 295 arthroplasties of the hip and knee joints was carried out to compare the effect of systemic Cefuroxime with Cefuroxime in bone cement in the prevention of early infection. There was no statistical difference in the incidence of early superficial or deep infection between the two groups. Both methods of administering Cefuroxime appear to be satisfactory in the prevention of early infection after total joint replacement.

Adult↗
PubMed1987

The effect of lateral and dorsal recumbency on cardiopulmonary function in the anaesthetised horse.

The effect of lateral and dorsal recumbency on cardiopulmonary function in six anaesthetised horses were compared. Cardiac output/kg, stroke volume/kg, alveolar ventilation, venous admixture, pulmonary shunt and blood-gas values were determined. From lateral to dorsal recumbency cardiac output/kg decreased non-significantly. A significant increase in pulmonary shunt occurred. A positive correlation between body mass and pulmonary shunt in dorsal recumbency was found. Alveolar ventilation increased significantly in dorsal recumbency when breathing air compared to oxygen.

Anesthesia, Intravenous↗
PubMed1986

An apparatus for collecting blood samples by radiotelemetry from horses during exercise.

An apparatus was designed to collect four consecutive blood samples from exercising horses. The collection of each sample was controlled by valves activated by radiotelemetry signals transmitted by an observer. Using the device, venous blood samples were collected from ten thoroughbred racehorses before, during and after a 400 m training gallop. Blood glucose increased markedly post-exercise. Both phosphorus and potassium concentrations increased during exercise, decreased post-exercise and recovered to pre-exercise levels within 120 minutes. The system was modified to collect anaerobic samples of arterial and venous blood, and the efficiency of the modified system was investigated in a standing conscious horse. Blood gas values of samples collected by means of the apparatus were compared with those collected manually and simultaneously, directly from the neck of the intravascular catheter. For eight pairs of arterial and venous samples, the coefficients "r" were 0.998 and 0.997 for PO2 and PCO2 respectively. It was concluded that the system worked efficiently and that the anaerobic sealing of the modified version was adequate.

Animals↗
PubMed1984

Pulmonary arterial haemodynamics and blood gas values of Thoroughbred racehorses with a history of epistaxis during a race.

In ten Thoroughbred racehorses which suffered epistaxis during a race, the mean pulmonary arterial diastolic pressure (PADP) was significantly higher, and the mean pulmonary arterial oxygen tension (PaO2) was significantly lower, than the corresponding mean values of a sample of fourteen clinically normal Thoroughbreds in training. The authors conclude that in horses with epistaxis during a race, pulmonary dysfunction may persist for up to two months after the episode, and that the results indicate a need for pulmonary function studies before and after racing, in order to resolve problems concerning exercise-induced pulmonary haemorrhage.

Animals↗
PubMed1984

The ratio of cardiopulmonary blood volume to stroke volume as an index of cardiac function in horses.

A method was developed for determining the ratio of cardiopulmonary blood volume to stroke volume, in horses. The radioisotope 99 Tc (technetium 99m pertechnetate) was injected into the jugular vein as a bolus, which was then detected in the right and left ventricles consecutively by a scanning device consisting of a Na I crystal, a collimator, an amplifier and a discriminator. The radiocardiogram (RCG) and the ECG were recorded simultaneously by a two-channel writing device. The ratio of cardiopulmonary blood volume to stroke volume (cardiopulmonary flow index = CPFI) was then determined from the RCG and ECG tracings. Five categories of horses were examined, viz. Thoroughbreds in training, showjumpers in training, horses not in training, horses with cardiovascular disease and horses with chronic lung disease. The mean CPFI of the above categories were respectively 7.0 +/- 0.39, 7.3 +/- 0.45, 6.7 +/- 0.61, 9.8 +/- 1.30 and 6.2 +/- 0.47. The mean CPFI of the subjects with heart disease was significantly greater than the mean values of the other four categories (P less than 0.001). It was concluded that the CPFI was a reproducible physiological parameter in horses and that the value was significantly increased in our series of subjects with heart disease.

Animals↗
PubMed1983

Studies on the physiopathology of chronic obstructive pulmonary disease in the horse. VIII. Mean modal vectors of the P wave and the QRS complex.

Mean modal vectors of P1, P2 and QRS were determined in the 3 planes of a semi-orthogonal EKG lead system in 17 horses and ponies with chronic obstructive pulmonary disease (COPD) and in 17 clinically normal horses and ponies. Subjects were paired so that the heart rates of each pair were not dissimilar by more than 2 cycles per minute. Probably significant differences were observed between the mean angles of P1 vectors in the transverse and sagittal planes (T plane, normal = 324 degrees +/- 24,6 degrees, COPD = 342 degrees +/- 21,0 degrees, t = 2,0, P less than 0,05; S plane, normal = 331 degrees +/- 22,6 degrees, COPD = 348 degrees +/- 16,2 degrees, t = 2,52, P less than 0,02). There were no significant differences between the mean angles of planar modal QRS vectors of normal subjects and those of COPD subjects.

Animals↗
PubMed1982

Aetiology and interrelationship of some common skeletal deformities. (Talipes equinovarus and calcaneovalgus, metatarsus varus, congenital dislocation of the hip, and infantile idiopathic scoliosis).

The Edinburgh Register of the Newborn 1964-1968 and the Edinburgh Scoliosis Clinic 1964-1971 have been used to establish the population frequency in the city of the idiopathic forms of talipes equinovarus and calcaneovalgus, metatarsus varus, congenital dislocation of the hip, and infantile scoliosis. A survey of 165 patients now aged 7 to 11 years showed an aetiological relationship, but with differing environmental factors. These factors were established by comparison with the Edinburgh Register control group of 692 normal infants born over the same period, giving a unique opportunity to obtain more accurate antenatal data than has previously been possible. The principal associations were: talipes equinovarus with antepartum haemorrhage and maternal hypertension; metatarsus varus with twin pregnancies; congenital dislocation of the hip with first born children, older than average fathers, breech presentation, a significant lack of menstrual problems in the mother, and maternal upper respiratory infection during pregnancy; infantile idiopathic scoliosis with breech presentation, prematurity, and the onset of the curve in the winter months. No significant association with raised intrauterine pressure (hydramnios or oligohydramnios) was found among these simple idiopathic deformities. It is concluded that the multifactorial genetic background in likely to be similar in all, but that the additional environmental element is variable.

Adult↗
PubMed1982

Studies on the physiopathology of chronic obstructive pulmonary disease in the horse. VII. Percentage venous admixture.

The percentage venous admixture was calculated in 21 clinically normal horses and ponies and in 13 horses and ponies with chronic obstructure pulmonary disease (COPD). The oxygen contents of pulmonary end-capillary blood, arterial and mixed venous blood were calculated from blood and respiratory gas values and substituted in the shunt equation. The mean percentage venous admixture of the COPD subjects was significantly greater than that of the normal subjects. It was concluded that a larger proportion of alveoli in the lungs of COPD subjects were hypoventilated than that of alveoli of the normal lungs.

Animals↗
PubMed1981

Studies on the physiopathology of chronic obstructive pulmonary disease in the horse. IV. Blood gas and acid-base values at rest.

Radiometer Blood Micro-system 2 was used in studies designed to, (a) compare the mean blood gas and acid-base values of 38 normal horses and 20 horses with chronic obstructive pulmonary disease (COPD), (b) determine the means and standard deviations of blood gas and acid-base values of Thoroughbred horses in training, and (c) investigate the relationships between clinical data, blood gas values, intracardiac and pulmonary arterial pressures in subjects with COPD. There were significant differences between the mean values for partial pressure of arterial oxygen (PaO2), arterial carbon dioxide (PaCO2) and mixed venous carbon dioxide (PvCO2) in normal and COPD subjects. The mean values and standard deviations for determinations of blood gases and acid-base status in Thoroughbred horses in training were as follows: PaO2 = 77,4 +/- 4,3 mm Hg; PvO2 (mixed venous oxygen partial pressure) = 36,2 +/- 4,1 mm Hg; PaCO2 = 40,9 +/- 5,8 mm Hg; PvCO2 = 49,4 +/- 5,0 mm Hg; pHa (arterial) = 7,358 +/- 0,051; pHv (venous) = 7,343 +/- 0,027; standard bicarbonate = 22,7 mM/l. The PaO2, the PaCO2 and the arterial pH were significantly correlated to the respiratory frequency in COPD subjects. The correlations of pulmonary diastolic pressure to both PaO2 and pHa were of probable significance (P less than 0,05) in COPD subjects. PaCO2 was highly significantly correlated to PaO2 and pHa in COPD subjects.

Acid-Base Equilibrium↗
PubMed1981

Studies on the physiopathology of chronic obstructive pulmonary disease in the horse. V. Blood gas and acid-base values during exercise.

The haemoglobin concentration, the partial pressures of oxygen and carbon dioxide, the oxygen content and the pH were determined in the arterial and mixed venous blood of 5 normal and 3 horses with chronic obstructive pulmonary disease (COPD) at 3 stages of an exercise distance of 1200 m. Arterial and mixed venous samples were collected simultaneously by means of an automatic technique during the walk, trot and gallop at 0-100 m, at 500-600 m and at 1100-1200 m. The standard bicarbonate and the lactic and pyruvic acid concentrations were also determined in arterial and mixed venous blood. Highly significant changes in the mean values of PvO2. O2 content and delta a-vO2 content occurred during exercise in COPD subjects, and significant changes in PvO2 and delta a-vO2 content occurred during exercise in normal subjects. We concluded that COPD subjects compensated for respiratory dysfunction during exercise by extracting more oxygen from the blood than did normal horses. There was a highly significant correlation between the changes in standard bicarbonate and the changes in lactic acid concentration during exercise in both normal and COPD subjects. This led to the conclusion that lactic acid production was primarily, but not completely, responsible for the metabolic acidosis of exercise in horses.

Animals↗
PubMed1980

Studies on the physiopathology of chronic obstructive pulmonary disease in the horse. III. The intrathoracic pressure.

The intrathoracic pressure was determined by direct intrapleural cannulation in 17 clinically normal horses and 14 horses with chronic obstructive pulmonary disease (COPD). There were significant differences between the normal and COPD horses with regard to max. Ppl and max. delta Ppl. The mean values for minimum Ppl of the 2 groups of subjects were not significantly different. The results were discussed in relation to those of other workers.

Animals↗
PubMed1980

Studies on the physiopathology of chronic obstructive pulmonary disease in horses. I. Clinical signs.

Twenty cases of chronic cough originating in the lung and associated with loss of performance were clinically examined. The physical signs observed were compared with those observed in a control series of 38 clinically normal horses. Reduced work tolerance, coughing for more than 3 months and abnormal pulmonary sounds (râles) were primary signs of chronic obstructive pulmonary disease (COPD). Forced abdominal expiratory efforts and pumping of the anus were regarded as confirmatory signs. Neither nasal discharge nor increased marginal distance was found to be a reliable sign of COPD. The mean respiratory frequency of the COPD subjects, namely 25,4 per minute, was significantly higher than the 16,7 per minute (P less than 0,001) of the 38 normal subjects.

Animals↗
PubMed1980

Studies on the physiopathology of chronic obstructive pulmonary disease in the horse. II. Right heart haemodynamics.

Pressure curves obtained by cardiac catheterization of the pulmonary artery, right ventricle and right atrium of 9 horses and ponies with chronic obstructive pulmonary disease (COPD) were compared with those similarly recorded from 6 clinically normal control subjects. The mean pulmonary peak systolic, pulmonary minimum diastolic and ventricular peak systolic pressures of the COPD subjects were significantly higher (P less than 0,01) than the corresponding mean pressures of the clinically normal control subjects. The mean pressure calculated from pressure curves obtained from 8 Thoroughbreds in training did not differ significantly from those of the clinically normal subjects not in training.

Animals↗
PubMed1979

Some aspects of the epidemiology of equine babesiosis.

The sex, coat colour, age, province and month of occurrence of every case of babesiosis was recorded in a horse population of 5856 in South Africa and Rhodesia. A total of 115 cases were recorded during the period 1973-01-01 to 1973-12-31. Chisquared tests were used to evaluate the significance of frequencies. Significant biases in the distribution of cases of babesiosis were found with regard to season (P < 0,05), sex (P < 0,001) and coat colour (P < 0.01).

Animals↗