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Biomedical subjects

D K Mason

Publications and source records attributed to D K Mason.

At least 19 recordsLinked to original sources
PubMed1998

Integration of primary care dental and medical services: a three-year study.

OBJECTIVE: To develop and evaluate a model of integrated primary dental and medical care. DESIGN: 3-year prospective study. SETTING: A general dental practice and a general medical practice occupying the same building in Glasgow. INTERVENTION: Regular staff meetings, joint use of patient records systems and information derived from patient questionnaires. Dentistry was included in established screening programmes such as child health surveillance and care of elderly. Staff were encouraged to participate in joint work practices and joint consultations were carried out. MAIN OUTCOME MEASURES: Patient registration, avoidance of discrepancies in information, reduction of secondary referrals, joint work practices. RESULTS: The number of registered joint patients attending both medical and dental practices increased by 90%. The joint use of patient record systems avoided discrepancies in patient information which would have affected the quality of patient care. Including dentistry in child health surveillance and care of elderly screening programmes resulted in an increase in 0-5 year olds registering with dentists from 36% to 68% (P < 0.001) and with > 75 year olds from 47% to 71% (P < 0.001). Joint consultations reduced the need for secondary referrals. CONCLUSIONS: This model of health care demonstrated the potential for coordination and integration of functions between the dental team and the primary care team. Integrated primary dental and medical care requires attitudinal change in health care professionals and requires greater emphasis in education and training of health care professionals in the future.

Adolescent↗
PubMed1994

Integration of primary care dental and medical services: a pilot investigation.

During the past decade the development of primary care medical services has been based on the medico-social model of health care delivery and this has resulted in the creation of the primary care team. These changes have so far not involved the general dental services. It was therefore decided to test the potential for coordination and integration of general dental practice in the primary care services. This started by examining a general medical and a general dental practice, occupying the same site, but functioning separately. Around 24% of patients were common to both practices. The initial data collected from a pilot study have been analysed and assessed in relation to patient attendance, record systems, staff cooperation, screening programmes, health promotion, patient referrals and staff education. The potential of this model for improving patient care and targeting the pre-school, middle-aged and elderly is described. It is concluded that coordinated primary care dental and medical services is an important area for further health services and educational research.

Dental Care↗
PubMed1990

Contributions of William Hunter (1718-1783) to dental science.

This article briefly describes some of the many and varied contributions which William Hunter made to medical and dental science in the eighteenth century. His work provided the foundations from which anatomy became one of the cornerstones of modern medicine. Hunter's teaching methods are still influential today and his specimen collection is one of the most comprehensive in existence.

Anatomy↗
PubMed1990

Haematological measurements as an aid to early diagnosis and prognosis of respiratory viral infections in thoroughbred horses.

In late November 1988 large numbers of thoroughbred horses in training in Hong Kong developed a transient pyrexia with, in some cases, the clinical signs of viral respiratory disease. Serial blood samples for haematological examination were taken from 10 of the horses which were stabled in six different blocks. They had developed a high temperature within three days of each other and subsequently seroconverted to equine herpes virus 1 (EHV1). The absolute monocyte count was more than 0.5 x 10(9)/litre in all 10 within the first five days, and nine of them had a high neutrophil/lymphocyte ratio on the first day, which then decreased and reversed within four or five days. Five of the horses had a high plasma viscosity, and a large difference between the viscosity of plasma and serum which in three of them returned to normal within 10 days. In the two and a half months after the initial infection six of nine of the horses, including the five which had a large difference between the viscosity of plasma and serum, developed visible mucopus by endoscopic examination. These haematological and endoscopic changes can be used to detect horses in the acute stages of EHV1 infection and monitor the progress of the disease, before it can be confirmed by isolation of the virus and, or, serology.

Animals↗
PubMed1989

William and John Hunter.

This article describes some of the contributions which the brothers William and John Hunter made to medical and dental science. John is revered in London and William in Glasgow. Both had an important influence on dentistry and its development as an academic subject.

Anatomy↗
PubMed1989

Haematological changes in two thoroughbred horses in training with confirmed equine herpesvirus 1 infections.

An outbreak of respiratory disease among thoroughbred horses in training in Hong Kong was caused by equine herpesvirus 1 (EHV-1) subtype 1 (abortion strain). Two of the horses affected by EHV-1 were serially blood sampled over a period of several weeks and their haematological values measured. There was an increase in monocyte count in the first few days which steadily decreased in one horse, but the other had a second monocyte peak after a period of exercise, thus demonstrating the importance of not working animals in the early stages of the disease.

Animals↗
PubMed1989

Effects of season and lower ambient temperature on the structure of the sweat glands in anhidrotic horses.

Histological studies of the sweat glands of anhidrotic horses in the Hong Kong summer and under conditions of reduced thermal stress, both natural and controlled, were undertaken to determine if glandular regeneration occurs. Clinical data were collected for comparison with the histological results in each instance. Horses were assigned to one of three categories on the basis of the resulting change in the number of thin glandular profiles in a cooler environment. Group 1, which was classed as normal, had a low initial value, which was maintained. Group 2, typical of mild and moderately affected animals, had a high initial value, which fell markedly after as little as six weeks in the cool environment. Animals in Group 3, classed as severely affected, had a high initial value which remained high even after prolonged exposure to the cool environment. Light microscopical examination of the sweat glands in the heat, and after six weeks in a cool environment, provided a means of predicting the degree of anhidrotic severity and the potential for recovery in a cool climate. This was superior to clinical observation, although a diagnostic test based on glandular function is still required.

Animals↗
PubMed1988

Dibasic amino acid interactions with Na+-independent transport system asc in horse erythrocytes. Kinetic evidence of functional and structural homology with Na+-dependent system ASC.

Amino acid transport in horse erythrocytes is regulated by three co-dominant allelomorphic genes coding for high-affinity transport activity (system asc1), low-affinity transport activity (system asc2) and transport-deficiency, respectively. The asc systems are selective for neutral amino acids of intermediate size, but unlike conventional system ASC, do not require Na+ for activity. In the present series of experiments we have used a combined kinetic and genetic approach to establish that dibasic amino acids are also asc substrates, systems asc1 and asc2 representing the only mediated routes of cationic amino acid transport in horse erythrocytes. Both transporters were found to exhibit a strong preference for dibasic amino acids compared with neutral amino acids of similar size. Apparent Km values (mM) for influx via system asc1 were L-lysine (9), L-ornithine (27), L-arginine (27), L-alanine (0.35). Corresponding Vmax estimates (mmol/l cells per h, 37 degrees C) were L-lysine (1.65), L-ornithine (2.15), L-arginine (0.54), L-alanine (1.69). Apparent Km values for L-lysine and L-ornithine influx via system asc2 were approximately 90 and greater than 100 mM, respectively, with Vmax values greater than 2 and greater than 1 mmol/l cells per h, respectively. Apparent Km and Vmax values for L-alanine uptake by system asc2 were 14 mM and 6.90 mmol/l cells per h. In contrast, L-arginine was transported by system asc2 with the same apparent Km as L-alanine (14 mM), but with a 77-fold lower Vmax. This dibasic amino acid was shown to cause cis- and trans-inhibition of system asc2 in a manner analogous to its interaction with system ASC, where the side-chain guanidinium group is considered to occupy the Na+-binding site on the transporter. Concentrations of extracellular L-arginine causing 50% inhibition of zero-trans L-alanine influx and half-maximum inhibition of L-alanine zero-trans efflux were 14 mM (extracellular L-alanine concentration 15 mM) and 3 mM (intracellular L-alanine concentration 15.5 mM), respectively. We interpret these observations as evidence of structural homology between the horse erythrocyte asc transporters and system ASC. Physiologically, intracellular L-arginine may function as an endogenous inhibitor of system asc2 activity.

Alanine↗
PubMed1988

Topographical similarities between harmaline inhibition sites on Na+-dependent amino acid transport system ASC in human erythrocytes and Na+-independent system asc in horse erythrocytes.

Na+-dependent system ASC and Na+-independent system asc are characterized by a common selectivity for neutral amino acids of intermediate size such as L-alanine and by their interactions with dibasic amino acids. For system ASC, the positive charge on the dibasic amino acid side chain is considered to occupy the Na+-binding site on the transporter. We report here the use of harmaline (a Na+-site inhibitor in some systems) as a probe of possible structural homology between these two classes of amino acid transporter. Harmaline was found to inhibit human erythrocyte system ASC noncompetitively with respect to L-alanine concentration, but approximated competitive inhibition with respect to Na+ concentration (apparent Ki = 2.0 and 0.9 mM, respectively). Similarly, harmaline noncompetitively inhibited L-alanine uptake by horse erythrocyte systems asc1 and asc2 (apparent Ki = 2.0 and 1.9 mM, respectively). In contrast, harmaline functioned as a competitive inhibitor of L-lysine uptake by system asc1 (apparent Ki = 2.6 mM). It is concluded that harmaline competes with Na+ for binding to system ASC and that a topographically similar harmaline inhibition site is present on system asc. This site does not however bind Na+, the asc1 transporter exhibiting normal L-alanine and L-lysine influx kinetics in the total absence of extracellular cations.

Alanine↗
PubMed1987

Exercise-induced pulmonary haemorrhage in the horse: results of a detailed clinical, post mortem and imaging study. I. Clinical profile of horses.

Detailed physical and clinical examinations were performed on 26 Thoroughbred racehorses which were used subsequently in a series of studies to investigate the contribution of the pulmonary and bronchial arterial circulations to the pathophysiology of exercise-induced pulmonary haemorrhage (EIPH). Twenty-five of the horses had been retired from race training in Hong Kong during the 1984-85 season, all but four raced that season; one horse had been retired the previous season. The average number of races for the group that season was 4.1 +/- 2 with an average distance of 1502 +/- 216 metres, mean racing speed 15.5 +/- 0.5 metres/sec. Time from last race to necropsy was 177 +/- 155 days, range 12 to 572 days. All but one horse had a known history of either EIPH or epistaxis. Time from last recorded incident of expistaxis (17 horses) to necropsy was 156 +/- 141 days, range 12 to 513 days, with a longer interval since last recorded endoscopic observation of EIPH. Focal abnormal lung sounds were detected in the dorsocaudal lungfields on auscultation during rebreathing in three horses and six had tracheobronchial cytology consistent with previous episodes of pulmonary haemorrhage (haemosiderophages). No other characteristics which might have allowed separation of this group of horses from other Thoroughbred horses recently in race training were identified.

Animals↗
PubMed1987

Exercise-induced pulmonary haemorrhage in the horse: results of a detailed clinical, post mortem and imaging study. II. Gross lung pathology.

Gross post mortem examinations were performed on the lungs of 26 Thoroughbred horses of known exercise-induced pulmonary haemorrhage (EIPH) status. The most consistent finding was a variable degree of bilaterally symmetrical, dark discolouration of the dorsocaudal regions of the caudal lung lobes. In more severely affected lungs, the stained areas extended cranially along the dorsal surfaces of the lungs, and in some cases affected approximately one third of the lung surface. Discoloured areas of lung were denser than normal, collapsed less readily, often contained trapped air and were slow to inflate. The subpleural bronchial arteries were more prominent in the discoloured regions. Pleural adhesions were noted in two horses but were not related to the discoloured lung regions. It was concluded that the discoloured lesions have a complex pathogenesis and were related directly to previous bouts of EIPH. Associated with them were signs indicating probable partial small airway obstruction, decreased tissue compliance and direct involvement of the bronchial arterial circulation.

Animals↗
PubMed1987

Exercise-induced pulmonary haemorrhage in the horse: results of a detailed clinical, post mortem and imaging study. III. Subgross findings in lungs subjected to latex perfusions of the bronchial and pulmonary arteries.

Latex was injected under pressure into bronchial and pulmonary arteries of the inflated lungs of Thoroughbreds and transverse sections taken to calculate the area of lesions resulting from exercise-induced pulmonary haemorrhage. Extensive areas of dense brown haemosiderin varying from 0 to 45 per cent of total lung volume were identified, predominantly in the dorsocaudal lungfields. Bronchial arterial proliferation appeared to have replaced the pulmonary supply in affected areas of the lung. Closely associated with the staining and bronchial arterialisation, there was widespread small airway disease. The most severely affected bronchioles contained thick gelatinous or mucous exudate or mucoid plugs and had grossly thickened walls. These lesions suggest that the source of haemorrhage in exercise-induced pulmonary haemorrhage is from alveolar capillaries anomalously supplied by the bronchial arterial circulation through the development of pathological shunts. Small airway disease is suggested as being of major importance in the pathogenesis of the disease and may have led to the initial proliferation of the bronchial circulation.

Animals↗
PubMed1987

Exercise-induced pulmonary haemorrhage in the horse: results of a detailed clinical, post mortem and imaging study. IV. Changes in the bronchial circulation demonstrated by C.T. scanning and microradiography.

The purpose of this study was to use radiographic contrast techniques and special imaging methods to identify and high-light bronchial arterial involvement in lung lesions associated with exercise-induced pulmonary haemorrhage (EIPH) in horses. The lungs from four horses with histories of EIPH were prepared for computerised tomographic scanning and microradiography by perfusing the broncho-oesophageal artery with a mixture of red latex and either barium or iodine contrast materials while the pulmonary supply received only blue latex. Computerised tomographic scan slices of the prepared inflated lungs were obtained from the caudal tip of the lung to the hilus. Microradiography of selected lung slices was also performed on a Faxitron. Diffuse areas of increased density, with preferential bronchial arterial supply noted on the computerised tomographic scans were confirmed by microradiography. Dense focal and diffuse plexuses of markedly hypertrophied and highly branched bronchial arterial networks were identified, centred around certain small airways. The vascular supply to these plexuses was recruited predominantly from neighbouring bronchial vessels, and in some cases, from the enlarged vasa vasorum of pulmonary arteries sending anastomoses to the affected areas. The authors conclude that bronchial vascular lesions in EIPH cases are the likely origin of haemorrhage; that small airway disease is the probable initiating stimulus for bronchial vascular proliferation in these lesions; and that the morphology and nature of the neovascular tissue in these lesions provides the conditions leading to haemorrhage in the lungs of horses with EIPH.

Animals↗