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Biomedical subjects

I Mackie

Publications and source records attributed to I Mackie.

At least 55 records · Page 3Linked to original sources
PubMed1990

The in-vitro and ex-vivo effects of chloroquine sulphate on platelet function: implications for malaria prophylaxis in patients with impaired haemostasis.

Platelet aggregation responses were studied in platelet-rich plasma from six healthy volunteers before and 2 and 6 h after ingestion of 600 mg chloroquine sulphate. Apart from a mild reduction in height of aggregation response to 1 microgram ml-1 collagen 2 h post-drug ingestion (mean percentage of pre-drug values +/- s.e.m. = 87.8% +/- 4.0%; P = 0.04), no significant differences were observed in platelet responses to ADP (1 and 5 microM) or collagen (1 and 4 micrograms ml-1) at 2 or 6 h post-chloroquine compared to the pre-drug values. In vitro, drug concentrations approximately 1000 times greater than those used therapeutically were required for 50% inhibition of platelet aggregation and ATP release in response to 5 microM ADP, 1 microgram ml-1 collagen and 4 micrograms ml-1 collagen (IC50 concentrations +/- s.e.m. for inhibition of aggregation = 98.5 +/- 3.7, 53.5 +/- 56.4 and 113.0 +/- 6.2 mg l-1 respectively; IC50s +/- s.e.m. for inhibition of ATP release = 0.9 +/- 0.2, 14.7 +/- 4.0 and 23.0 +/- 5.3 mg l-1 respectively). These data provide no cause for concern in using chloroquine for malaria prophylaxis in patients with impaired haemostasis.

Adenosine Diphosphate↗
PubMed1988

Drowning and near-drowning on Australian beaches patrolled by life-savers: a 10-year study, 1973-1983.

Resuscitation report-forms of the Surf Life-Saving Association of Australia, for the period 1973-1983, were analysed. During this period there were 262 immersion victims at beaches that were patrolled by life-savers. Of these, 162 victims survived, some of whom received expired-air resuscitation (n = 61) or cardiopulmonary resuscitation (n = 29). Among those who drowned, none was younger than five years of age. Vomiting and regurgitation were major problems during resuscitation. Respiratory and cardiopulmonary arrest occurred after apparently-successful rescue; this highlights the necessity for the close observation of victims and the early administration of oxygen to all immersion victims. Resuscitation in deep water has been shown to be effective, and instruction in these techniques is now standard teaching within the Surf Life-Saving Association of Australia.

Adolescent↗
PubMed1986

The prevention of wound contamination by skin organisms by the pre-operative application of an iodophor impregnated plastic adhesive drape.

Prior to preparing the skin for surgery, samples for bacterial growth were taken from 107 patients. The same site was sampled after preparation with povidone-iodine and at the end of surgical procedure the deep part of the wound was also sampled. This demonstrated that the wounds of 15% of patients became contaminated by organisms present on the skin prior to disinfection. A comparison was made with a further 122 patients undergoing hip surgery in whom an iodophor impregnated plastic adhesive drape ('Ioban') was applied to the operation site 24 hours prior to surgery. Bacterial sampling of the wound at the end of the procedure showed that wound contamination was reduced from 15% to 1.6% by this method. When patients are to have implant surgery, the protection from contamination by skin organisms afforded by 'Ioban' drape is likely to prove a valuable tool in the fight to prevent infection.

Antisepsis↗
PubMed1985

Vibration analysis in the assessment of conservatively managed tibial fractures.

A simple and quantitative method for the assessment of fracture healing has been developed. this method depends on a technique of vibration analysis evolved from a study of 30 intact human tibiae and has been applied to the study of 22 tibial fractures. Real time vibration analysis will allow quantitative comparisons of different methods of non-operative fracture management, and, in addition to providing a uniquely powerful research tool, may have value in aiding clinical management decisions.

Biomedical Engineering↗
PubMed1985

Factors affecting the incidence of hip dislocation in cerebral palsy.

We have studied the natural history of spontaneous dislocation of the hip in cerebral palsy, with particular reference to the pattern of neurological involvement. In patients with bilateral hemiplegia and severe involvement of the upper limbs the incidence of dislocation was very high (59%), while in those with diplegia and little involvement of the upper limbs, only 6.5% were affected. There was no evidence of dysplasia or instability of the hip in any of the patients with unilateral hemiplegia. A strong correlation was found between the stability of the hip and the patients' ability to walk. These findings have a bearing on clinical surveillance and also on the indications for prophylactic surgery.

Adolescent↗
PubMed1984

Direct and indirect determination of tibial natural frequency--a comparison of frequency domain analysis and fast Fourier transform.

The natural frequency of in vivo mechanical systems has been derived in the past by signal conditioning techniques. For the living tibia the accuracy of this derived method was not validated. In addition the use of Fast Fourier Transform is time consuming, tedious and expensive. Direct measurement yields results which are more accurate, more easily obtained, and more clinically applicable.

Biomechanical Phenomena↗
PubMed1984

Vibration analysis of human tibia: the effect of soft tissue on the output from skin-mounted accelerometers.

The vibration response of bone can be recorded from a skin-mounted accelerometer, but only if it is sufficiently preloaded to overcome the damping effect of the interposed soft tissue. Excessive preload results in distortion of the recorded signal by a high-frequency component which probably originates in the supporting apparatus of the accelerometer. The required preload is proportional to the soft tissue thickness, but for any given soft tissue thickness, the range of allowable preload is fairly wide.

Acceleration↗
PubMed1984

Natural frequency of fracture fragments in the assessment of tibial fracture healing.

The natural frequency of fracture fragments has been measured at various times in the course of healing of 11 midshaft tibial fractures. The major fragments manifest different frequencies which are themselves distinct from that of the intact bone. It has been shown that the difference in frequency between the major fragments falls with time, so that the separate frequencies approach a common value which corresponds with the healed state. The results have been used to construct a model healing curve, against which other tibial fractures can be compared.

Adolescent↗
PubMed1984

Abdominal girth: an unreliable measure of intra-abdominal bleeding.

The measurement of abdominal girth in an attempt to detect intra-abdominal bleeding may be dangerously misleading. It is an inaccurate measure of intra-abdominal collection of fluid. The results show that measurements are heavily biased by the expectations of observers, with the result that a considerable change in girth is likely to be ignored. The error caused by observer bias is much greater than the distension which actually occurs when fluid collects in the abdomen over a short period.

Abdomen↗
PubMed1984

Late repair of the calcaneal tendon with carbon fibre.

Ruptures of the calcaneal tendon which present late may be repaired using carbon fibre to induce a neotendon. The operative technique is described and the results of five cases reviewed. The average muscle power obtained was 88% of normal, and the thickness of the neotendon was 148% of that of the normal side. It would appear that this tendon formation in man is comparable to that previously described in sheep.

Achilles Tendon↗
PubMed1984

Impaired vessel wall response to venous occlusion in patients with chronic renal failure on maintenance hemodialysis.

We have studied vessel wall function in two groups of patients with chronic renal failure - 1) conservative treatment only and 2) maintenance hemodialysis. Three proteins synthesized by vascular endothelium-plasminogen activator (PA), factor VIII related antigen (VIII:RAg) and antithrombin III (ATIII) - were assayed before and after a fifteen minute period of venous occlusion. The release of PA was significantly reduced in patients on maintenance hemodialysis as compared to both undialyzed uremics and controls. Lesser amounts of VIII:RAg were also released by hemodialysis patients than by undialyzed uremics. These defects, which are suggestive of vessel wall dysfunction on maintenance hemodialysis, may contribute to the high incidence of arteriopathy and thrombotic disease observed in this group of patients.

Adult↗
PubMed1982

Preservative-related problems in soft contact lens wearers.

Details of 61 patients are presented who, having worn soft contact lenses for many months, developed red eyes, conjunctival irritation with minimal discharge, and progressive loss of tolerance of the lenses. Investigations revealed an absence of infective agents and the clinical course after treatment with preservative-free solutions strongly suggested that preservatives, especially organic mercurials, were responsible for the changes. The corneal signs were slow to clear but after resolution the majority of patients were able to return to soft contact lens wear using a heat disinfection system with preservative-free solutions. Skin testing to a wide range of substances, including preservatives, contact lens solutions, and common sensitizers, revealed only one responder to Thiomersal out of 21 tested. However a rapid response followed conjunctival challenge with 0.005 per cent Thiomersal in normal saline in all subjects tested.

Contact Lenses, Hydrophilic↗
PubMed1980

Antithrombin III in patients on long-term oral anticoagulants.

The antithrombin III (AT III) concentration in plasma was measured in 63 patients on oral anticoagulant treatment (mean age 57.7 years), 26 healthy laboratory controls (mean age 28 years), and 21 patients attending the hypertensive clinic who had never been on oral anticoagulants (mean age 50 years). Three methods were used to measure AT III: a coagulation assay, a chromogenic substrate assay, and an immunological assay. In patients on oral anticoagulants, the mean values for AT III in the three assays were: 124%, 107%, and 96% respectively. The mean AT III concentration in laboratory staff was 103.4%, 94%, and 104.1% for the three assays; patients attending the hypertensive clinic had AT III concentrations indistinguishable from those in patients on oral anticoagulants: 117.9%, 110.5%, and 93.9%. The difference between both patient groups and laboratory staff was statistically highly significant, but no difference was demonstrated between patients on anticoagulant treatment and those not receiving it. Our results show that the increase in the functional AT III concentration (measured by coagulation and chromogenic assays) observed in patients on oral anticoagulants is probably due to the effects of age and underlying disease rather than to the anticoagulant treatment itself.

Adult↗